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P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �
Proceedings of the National Seminar : 23 Nov 20�0
2 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 3
Proceedings of the National Seminar : 23 Nov 20�0
SOUVENIR
PROcEEdINgS Of thE NatIONal SEmINaR ON
REcENt tRENdS IN BallIStIcS aNd matERIal ScIENcE( November 23 , 20�0 )
Organised byP. G. DePartment of aPPlieD Physics anD Ballistics
Fakir Mohan University Vyasa Vihar , South Campus, Balasore-7560�9 , Orissa
Website: www.fmuniversity.nic.in
� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
Editorial Board :Editor-in-Chief : Flt Lt Dr Munesh Chandra AdhikaryEditors : Prof Govinda Chandra Rout Dr Sidhartha Pattanaik Dr Santosh Kumar Agarwalla Er Ashanta Ranjan Routray
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Proceedings of the National Seminar : 23 Nov 20�0
6 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
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Proceedings of the National Seminar : 23 Nov 20�0
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About the Department
The Department of Applied Physics and Ballistics was established
in the year 2007 as a regular Post Graduate Department of Fakir Mohan
University, Balasore, Orissa. This Department offers the course like M.Sc
in Applied Physics and Ballistics having a strength of �6 with two Special
Papers like Ballistics and Electronics.. The uniqueness of the Department
is that it is the first and only Post Graduate Department under a
general State University , all over the country, introducing a course like
Ballistics with a vision to fulfill the requirement of defence research and
development services.
The vision of this department is to become a center of excellence
in education and research in the field of Applied Physics and Ballistics.
And its mission is to achieve success in University examinations, National
level competetive examinations like NET, GATE,JEST, SLET etc and also
in the qualifying examinations of DRDO , UPSC and othe research
institutes.
The syllabus of M.Sc. course has been framed based on the latest
UGC curriculum as well as various national level tests like NET, GATE etc.
In addition to the general topics of Physics , it includes most innovative
topics like Internal Ballistics, External Ballistics, Terminal Ballistics, Weapon
Systems, Ballistics Instruments, Rocket Ballistics, Modelling & Simulations,
Fluid Dynamics and Material Science etc. It provides the Special Paper
like Ballistics and Electronics. The Department is fortunate to have a team
�0 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
of well trained, young and dynamic teaching staffs having determination to impart quality teaching.
Apart from the lecture time, interaction with students is the top priority of all the staff members. The
specialized topics are covered by the reputed scientists of Proof and Experimental Establishments ( PXE
) and Integrated Test Range ( ITR ) , Chandipur.
The Department motivates the students to persue research career and at present it gives the
opportunity for doctoral degree in the emerging fields like Condensed Matter Physics, Material Science
( Nanotechnology) , Nuclear Physics, Ballistics and Computer Science. The experimental facilities for
the M.Sc. students are provided by its various labs like Computational Physics Lab, Modern Physics Lab,
Material Science and Ballistics Lab and Electronics Lab. For advance researches, a new Advanced Research
Laboratory is set up having the imported equipments like Scanning Electron Microscope ( SEM ) with
EDX , Fourier Transform Infra Red ( FTIR ) with TGA-�000 and others Universal Testing Machine ( UTM ) ,
Internal Mixer, Hot Air Oven, Hydraulic Press etc. Future vision is there to procure X-Ray Diffractometer (
XRD ), Impedance Analyser, Atomic Force Microscope ( AFM ) , LASER etc.
As the heighlights of Department , it provides a number of facilities to the students like
internet access through wireless LAN, Seminar library books, reading room , Class rooms provided with
audio-visual systems, LCD Projectors, Computers etc. The departmental seminars have been conducted
regularly involving the students , teachers and invited speakers from outside renouned research
institutes, universities , DRDO labs and even from abroad. The students are sent to DRDO Labs like PXE
and ITR, Chandipur for their Project works as requirement of University examination. Besides, number
of students are sent each year for undergoing Summer Training Courses at different renouned research
institutes of India like Variable Electron Cyclotron Centre( VECC ), Kolkata ; Institute of Plasma Research (
IPR ) , Ahamadabad ; Physical Research Laboratory ( PRL) , Ahamadabad; Bose Institute of Basic Sciences,
Kolkata ; Institute of Physics ( IOP ), Bhubaneswar etc. Further all the students as per requirement, are
exposed to workshops & Continuing Education Programme( CEP ) conducted at PXE, Chandipur. Above
all, our students are given free coaching for the preparation of various competitive examination like NET,
GATE, JEST, SLET etc. on Sundays and holidays by the internal as well as external faculties.
So finally this Department keeps the vision of Fakir Mohan University to excel in five ethoses :
• The Culture of Excellence
• The Culture of Innovation
• The Culture of Quality
• The Culture of Flexibility and Dynamism
• The Culture of Sustainability
**********************
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �
Proceedings of the National Seminar : 23 Nov 20�0
RECENT TRENDS IN BALLISTICS AND MATERIAL SCIENCE
V. Anguswamy
Scientist-F, Associate Director, PXE, DRDO, Chandipur
introDUction
Ballistics is the science of mechanics that deals
with the flight, behaviour, and effects of projectiles,
especially bullets, gravity bombs, rockets, or
the like; the science or art of designing and
accelerating projectiles so as to achieve a desired
performance.
The field of ballistics can be broadly
classified into three major disciplines: interior
ballistics, exterior ballistics, and terminal ballistics.
In some instances, a fourth category named
intermediate ballistics has been used.
Interior ballistics deals with the
interaction of the gun, projectile, and propelling
charge before emergency of the projectile from
the muzzle of the gun. This category would include
the ignition process of the propellant, the burning
of propellant in the chamber, pressurization of the
chamber, the first-motion event of the projectile,
engraving of any rotating band and obturation
of the chamber, in-bore dynamic of the projectile,
and tube dynamics during the firing cycle.
internal Ballistic
A ballistic body is a body which is free to move,
behave, and be modified in appearance, contour,
or texture by ambient conditions, substances, or
forces, as by the pressure of gases in a gun, by
rifling in a barrel, by gravity, by temperature, or
by air particles. A ballistic missile is a missile only
governed by the laws of classical mechanics.
ProPellant charGe
(Load density and consistency)
Load density is percentage of the space
in the cartridge of the3 space in the cartridge case
that is filled with powder. In general, loads close
to �00% density (or even loads where seating the
bullet in the case, compresses the poser) ignite and
burn more consistently than lower-density loads.
In cartridges surviving from the black-powder era,
the case is much larger than is needed to hold
the maximum charge of high-density smokeless
powder. This extra room allows the power to shift
in the case, piling up near the front or back of the
case and potentially causing significant variations
in burning rate, as powder near the rear of the
case will ignite rapidly but powder near the front
of the case will ignite later. This charge has less
impact with fast powders. Such high-capacity, low-
Invited Paper
2 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
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density cartridges generally deliver best accuracy
with the fastest appropriate powder, although this
keeps the total energy low due to the sharp high-
pressure peak.
Peak vs area
Energy is defined as a force exerted over a
distance; for example, the work required to lift
a one-pound weight, one foot against the pull
of gravity defines a foot- pound of energy (One
joule is equal to energy used to move a body
over a distance of one meter using one Newton
of force). If we were to modify the graph to reflect
pressure as a function of distance, the area under
that curve would be the total energy imparted to
the bullet. From this, it can be seen that the way to
increase the energy of the bullet is to increase the
are under that curve, either by raising the average
pressure, or increasing the distance, the bullet
travels under pressure (in other words, lengthen
the barrel).
Propellant burnout
Another issue to consider, when choosing a
powder burn rate, is the time the powder takes
to completely burn vs. the time the bullet spends
in the barrel. Since the burn rate of nitrocellulose-
based powders increases with increasing pressure,
this can be a very difficult interaction to guess,
and requires careful testing with gradual changes.
Looking carefully at the left graph, there is a
change in the curve, at about 0.� ms. This is the
point at which the powder is completely burned,
and no new gas is created. With a faster powder,
burnout occurs earlier, and with the slower
powder, it occurs later. Propellant that is unburned
when the bullet reaches the muzzle is wasted — it
adds no energy to the bullet, but it does add to
the recoil and muzzle blast. For maximum power,
the powder should burn until the bullet is just
short of the muzzle.
Since smokeless powders burn, not
detonate, the reaction can only take place on the
surface of the powder. Smokeless powders come
in a variety of shapes, which serve to determine
how fast they burn, and also how the burn rate
changes as the powder burns. The simplest shape
is a ball powder, which is in the form of round
or slightly flattened spheres. Ball powder has a
comparatively small surface-area-to-volume ratio,
so it burns comparatively slowly, and as it burns, its
surface area decreases. This means as the powder
burns, the burn rate slows down.
To some degree, this can be offset by
the use of a retardant coating on the surface of
the powder, which slows the initial burn rate and
flattens out the rate of change. Ball powders are
generally formulated as slow pistol powders, or
fast rifle powders.
This is a graph of a simulation of the 5.56 mm NATO
round, being fired from a 20-inch (510 mm) barrel.
The horizontal axis represents time, the vertical axis
represents pressure (green line), bullet travel (red
line), and bullet velocity (light blue line). The values
shown at top are peak values
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 3
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Flake powders are in the form of flat, round flakes
which have a relatively high surface-area-to-
volume ratio. Flake powders have a nearly constant
rate of burn, and are usually formulated as fast
pistol or shotgun powders. The last common
shape is an extruded powder, which is in the form
of a cylinder, sometimes hollow. Extruded powders
generally have a lower ratio of nitroglycerin to
nitrocellulose, and are often progressive burning
— that is, they burn at a faster rate as they burn.
Extruded powders are generally medium to slow
rifle powders.
eXternal Ballistics
Just two key factors determine the external
ballistics of a projectile; the muzzle velocity
and the ballistic coefficient. The ballistic
coefficient is significant because it determines
the rate at which the projectile slows down, and in
conjunction with the muzzle velocity this decides
the maximum range (at any given elevation) and
the time of flight to any particular distance. The
time of flight in turn decides the amount by which
the projectile drops downwards as this happens
at a constant rate due to gravity. The curved path
of the projectile which results from the muzzle
velocity, the ballistic coefficient and gravity drop
is called the trajectory.
In most types of long-range shooting
(whether by rifles or large cannon) a short time of
flight is considered desirable because it maximizes
the hit probability by reducing the time of flight
and flattening the trajectory. It also results in the
projectile striking the target at a high velocity and
therefore with greater effect. The main exception
is when artillery fires in the “upper register” (above
�5 degrees elevation) to achieve plunging fire.
The advantages of a high muzzle velocity
in reducing the time of flight are self-evident. So
are the disadvantages: more propellant is required,
the barrel will need to be longer, the gun will be
This graph shows different pressure curves for powders with different burn rates. The leftmost graph is the
same as the large graph above. The middle graph shows a powder with a 25% faster burn rate, and the
rightmost graph shows a powder with a 20% slower burn rate.
� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
heavier and (in the case of a mounted weapon)
so will be the mounting to cope with the greater
recoil. In an automatic weapon, the rate of fire is
also usually lower. As we have seen, there is also
a practical limit to how high the velocity of any
given projectile can be pushed. To make the most
of the muzzle velocity, we need to achieve a high
ballistic coefficient.
There are two elements which decide the
ballistic coefficient (Bc); the sectional density
(sD) and the form factor (ff). The SD is a simple
calculation as it is the ratio between calibre and
projectile weight. The formula is:
For metric measurements: multiply
the projectile weight in grams by �.�22, then
divide the result by the square of the calibre in
millimetres. So for a �2.7mm bullet weighing �0
grams: (�0x�.�22)/(�2.7x�2.7) = an SD of 0.353
For Imperial measurements: divide the
projectile weight in pounds by the square of the
calibre in inches (if bullet weights are in grains,
divide the result by 7,000).
The higher the SD figure, the better the
velocity retention (assuming equal form factors).
What the SD measures is the weight (or
momentum, when moving) behind every square
millimetre of the projectile calibre (i.e. the cross-
sectional area of the projectile). If projectiles were
solid cylinders then for a given SD figure they would
all be the same length regardless of their calibre. In
practice, of course, the length varies with the calibre;
a �0mm projectile will be about twice the length of
a 20mm, and will therefore have about double the
SD figure. This explains why artillery shells travel
much further than rifle bullets, no matter how fast
or streamlined. Other things being equal, the bigger
the calibre, the longer the range and the shorter the
flight time to any given range.
The first problem is that the FF is different
at subsonic and supersonic velocities, because
shapes which work best at subsonic speeds are
not the best at supersonic velocities. At subsonic
speeds, the drag caused by the low-pressure area
created at the back or base of the projectile is
significant, and major reductions in drag can be
made by tapering this to some extent (streamlining
or boat-tailing). At supersonic speeds, it is the
nose shape that is critical; finely pointed noses
are needed, but the back end doesn’t matter so
much. Some taper towards the base is useful, but
the optimum taper angle is different from that at
subsonic velocities. The benefit of boat-tailing at
very long range can be demonstrated by two .30-
06 bullets, both weighing ��0 grains (��.7g) and
fired at 2,700 fps (�23 m/s). At sea level, the flat-
based bullet will travel a maximum of 3,�00m, the
boat-tail 5,200m.
A further factor affecting military
projectiles is the addition of tracer elements.
These generate gas which helps to fill the low-
pressure area at the base, reducing drag. This gives
them a different trajectory by comparison with
non-tracer rounds, not helped by the fact that as
the tracer burns up the weight of the projectile
reduces, thereby worsening its sectional density.
Tracers can therefore never achieve a perfect
match with other projectiles and can only ever be
an approximate guide to their trajectory.
Putting all of this together, the most
aerodynamically sophisticated projectiles in use
today are the long-range artillery shells known as
erfBBB (extended-range full-bore base-bleed).
These have a long, finely pointed nose to work well
at their initial supersonic speeds, and a tapered
base filled with a “base bleed” burning chemical
which essentially does the same aerodynamic job
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Proceedings of the National Seminar : 23 Nov 20�0
as a tracer. Furthermore, the nose is so pointed
that only the base of the shell is in contact with
the barrel, so small streamlined stubs are fitted
part way up the shell to keep it centred in the
bore. It was discovered that these generate some
aerodynamic lift, like tiny wings, and extend the
range still further. The advantage of all of this
can be seen in the range improvement over a
conventional �55mm HE shell; in a 39 calibre barrel,
the standard M�07 shell has a range of ��,�00m,
the ERFB shell 25,500m and the ERFBBB 32,�00m.
Furthermore, unlike rocket-assisted or sub-calibre
shells, there is no penalty in effectiveness as they
carry at least as much HE (in fact, the South African
�55mm M57 ERFB shell contains 30% more HE
than the standard M�07 shell).
terminal Ballistics
There are two different aspects to this; the effect
of projectile strike against soft targets (animals or
people) and the effect against armour. The former
is described in more detail here.
First, against soft targets (the squeamish
have permission to duck this section!). A military
(i.e. fully jacketed, pointed, non-expanding) rifle
bullet will be destabilised when hitting a soft
target and will tumble. This is because its shape
means that the centre of gravity of the bullet
is towards the rear so it naturally prefers to fly
base-first. Spinning the bullet by means of the
rifling keeps the bullet flying point-first through
the air, but flesh is about �00 times denser than
air so spinning is no longer enough; the bullet
destabilises and turns over to travel base-first,
a process known as tumbling. In so doing it
obviously inflicts a far more serious wound than
if it carried on flying straight through the body.
Incidentally, bullets designed for penetrating
heavy game animals like elephant - which need to
penetrate very deeply in a straight line and must
therefore not yaw or tumble - have long, parallel
sides and blunt round noses, just like early military
rifle bullets.
Not all bullets tumble at the same rate.
Other things being equal, small bullets will tumble
more quickly than large ones, but the design of
the bullet is also important; some visually identical
bullets will tumble at different speeds, generally
depending on the internal construction. For
example, the Yugoslavian bullet for the 7.62x39
has a lead core and has been found in tests to
tumble much more quickly than the Russian steel-
cored bullet in the same cartridge. Various tricks
have been used to increase the probability of a
bullet tumbling; the British .303 Mk VII bullet had a
lightweight tip filler with the weight concentrated
towards the rear of the bullet, and the current
Russian 5.�5mm rifle bullet has a hollow tip.
If a bullet has a relatively weak jacket, the
stresses of tumbling may cause it to break apart
while it is travelling sideways through flesh - a
process known as fragmentation - which further
increases the wounding effect. Most 5.56x�5
military bullets fragment, although they have to
be travelling at high velocity to do so. This limits
their maximum effectiveness to fairly short range,
particularly from short-barrelled carbines which
have a lower muzzle velocity. Most 7.62x5� NATO
bullets do not fragment, although the German
one does - by accident rather than design.
Fragmentation is not an official requirement for
any military bullets; if it were, there might be some
legal challenge over the international prohibition
on bullets designed to cause unnecessary
suffering. The noses of hunting rifle bullets (and
6 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
many commercial handgun bullets) are designed
to expand on impact, which greatly increases the
size of the wound channel. Such bullets are illegal
for military use.
It is often claimed by hunters that as the
striking velocity of the bullet increases beyond
about 700 m/s (2,300 fps), so hydrostatic shock
begins to appear, with the effect that animals drop
dead much more dramatically than if hit in the
same place with a low-velocity bullet. However, this
effect does not seem to be replicated in people;
there are many cases of soldiers continuing to
fight for some time despite receiving severe (and
ultimately fatal) wounds from high-velocity rifle
bullets. Furthermore, serious shock effects are
only likely if the bullet exceeds the speed of sound
in flesh, which is around �,500 m/s (�,900 fps), but
even this has been disputed.
This brings us onto the vexed question of
stopping power, about which it is impossible to
make any pronouncements without stimulating
fierce arguments. Stopping power may be defined
as the ability of a particular weapon to immediately
disable an opponent so he can take no further
part in the fighting. It is not the same as lethality;
quite low-powered weapons can be lethal, but
considerably more power is normally required to
achieve reliable stopping power. Incidentally, this
shows that the notion that modern military rifle
bullets are meant to wound rather than kill is a
myth; if it is powerful enough to disable, it is more
than powerful enough to kill.
Materials
Various materials are use in mechanical devices,
components, & systems; these materials are
selected & applied based on their merits. It is
required above all that they conform to all of the
design specifications & requirements. They must
either be readily available in the specified final
form, or they must be capable of being made and
processed with minimum effort, be repairable,
and serviceable during use. They should also be
economical in general.
metallic materials are the prime
materials of choice, and steels of all kinds get the
first pick. In addition, copper alloys, such as brasses
and bronzes, are widely used due to their excellent
thermal conduction characteristics. Among the
light metals, aluminum alloys and titanium alloys
find widespread applications. Superalloys based
on nickel or cobalt or iron are widely sought after.
Although several other metallic materials do find
some applications in Armament systems.
Ceramic Materials
Ceramics are used in Armament applications
because of their inertness, hardness, were and
corrosion resistances, and insulation traits. They
are also able to withstand fairly high temperatures
without any deterioration. Ceramics are light and
creep resistant generally. They are inherently
brittle. Important ceramics are : oxides, nitrides
and silicates. carbides are also considered as
ceramics.
Plastics and Polymeric Materials
Polymers are giant organic molecules synthesized
from smaller compounds. They are essentially
based on group � non-transition elements.
They are of two varieties : one based on carbon
and the other on silicon ( the silicones). Because
combinations of both of these elements in
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Proceedings of the National Seminar : 23 Nov 20�0
organic molecules is possible, there are polymeric
compounds containing both carbon and silicon.
Composites are generally three-
dimensional, man-made materials that contains
two or more distinct component material types,
such as metals, ceramics, and polymers, or phases
with vastly different properties, such as Kevlar
fibers strengthening nylon; these are unified to
develop the best of both types, that is, to extract
unique and optimum properties that are not
available otherwise. A unique interface exists
among the component entities, the matrix, and
the strengthening agent. Indeed this is the cause
for some of the weakness encountered in some
composites.
Under the man- made category of
composites, five important classes can be identified
based on the component materials present. In all
of these composites, there is a continuous matrix
into which a second-phase or different material
kind is embedded. The matrix material or phase
should also be dominate, meaning it should
occupy the bulk of the volume. The five classes
of composites are : polymer-matrix composites
(PMCs), metal-matrix composites (MMCs), ceramic-
matrix composites (CMCs), bio-matrix composites
(BMCs), and similar material composites (SMCs).
Within these classes, the composites are also sub-
divided as fiber-reinforced, particle-reinforced
or dispersion strengthened, and laminate types;
these sub-divisions depend on the morphological
features of the strengthening second material or
phase component.
conclUsion
Conventional Armaments continues to play a
decisive role even in the present scenario of
nuclear weapons and electronic warfare. As a war
fighting technology, they are low cost, reliable,
highly effective and proven in several battle
field situations. Application of advancements
in electronics, materials and manufacturing
technologies, computers and propulsion
technologies has added new dimensions to
armament technology.
reference
[�] Donald E. Carlucci and Sidney S. Jacobson -“Ballisitcs” Theory and Design of Gun and ammunition
[2] GM Moss, , D W Leeming & C L Farrar -“ Military Ballistics”
[3] A Raman-“Materials selection and application in Mechanical Engineering”
[�] Ludwing Stiefel - “Gun Propulsion Technology”
[5] Jaiprakash Agrawal -“High energy Materials”
[6] Richard M Lloyd -“Conventional Warhead systems
Physics And Engineering Design
� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
MULTI-TARGET TRACKING IN A TEST RANGE SCENARIO
R Appavu Raj
Sc ‘G’, Additional Director, Integrated Test Range, Chandipur
Abstract
Integrated Test Range (ITR) handles various types of multiple target flight trials.
To facilitate target tracking and estimation in such multi-target scenario, nearest
neighbourhood (NN) technique based data association algorithm has been adopted
at ITR. The present paper discusses the NN-based data association algorithm and its
performance in a real flight trial situation by using multiple-target track data from a
multi-target tracking radar.
1. introDUction
Integrated Test Range (ITR), Chandipur handles
test and evaluation of short, medium and long
range guided missiles, rockets and various other
air-borne objects. Ensuring safety of life and
properties in and around the launch corridor
is indispensable requirement during test and
evaluation of these developmental flight vehicles.
This necessitates real time monitoring of the flight
vehicle’s trajectory and health status with that of
the desired one. This in turn is possible with the use
of an efficient tracking and estimation algorithm
which extracts useful information from multiple
tracking sensor’s noisy measurement data for the
purpose of real time flight safety monitoring as
well as for post-flight performance analysis.
The different flight scenarios encountered
at ITR are engagement of multiple targets by
multiple missiles, ejection of multiple payloads,
engagement of air to air missiles, etc. In view of
this, the target tracking and estimation algorithm
should be capable of detecting and tracking
different targets by utilizing the measurements
from various sensors. In a multi-target tracking
situation, a single sensor or a number of sensors
can observe multiple targets at a time. Assessment
of the actual scenario in such situations becomes
complicated due to increased level of uncertainties
as opposed to single target tracking. In addition to
the presence of measurement noise of unknown
or partially known statistical properties, the source
responsible for each measurement is unknown in
this case. The situation gets further complex in
presence of false alarm & clutter and when the
number of targets is also unknown. In a dense
target scenario, it is very difficult to associate a
measurement with its source (even when each of
the targets is resolved by the sensors) with certainty.
On the other hand, the inherent limitations of the
tracking sensors may fail to resolve closely spaced
targets and thus inhibit appropriate assessment
of target scenario. Hence, the central problem
in multi-target tracking is data association, i.e.,
identifying the target responsible for individual
measurement. Further, the algorithm must have
efficient methodology for track initiation and
track deletion.
Commonly used association techniques
are distance measure, association coefficient,
correlation coefficient, probabilistic similarity
measures etc. [�]. Based on these techniques,
there are a number of algorithms for tracking
in multiple target environment [2], e.g. track
splitting approach, nearest neighbourhood
method, maximum likelihood method, Bayesian
approach etc. In track-splitting approach, a track
is split, whenever more than one detection
is observed in the neighbourhood of the
predicted measurement. The likelihood function
of each trajectory is computed and the track is
dropped when the likelihood value is less than a
predetermined threshold. Although this method
is suitable for track initiation and update, memory
and computational requirements become very
high in a dense target environment. For simplicity
as well as efficiency of the algorithm, Nearest
Neighbourhood based data association algorithm
has gained popularity. It is accomplished by
defining a measure of association that quantifies
the closeness between measurement pairs or
measurement to track pairs. There are some
difficulties in performing multi sensor tracking
due to uncertain data and disparate data
sources. The identity of the targets responsible
for each individual data set is unknown, so there
is uncertainty as how to associate data from
one sensor which are obtained at one time and
location to those of another sensor at another
point in time and location. Tracking is further
complicated by the fact that some sensors may
not observe the targets due to the variation of
signals and the sensor characteristics. Also, false
alarms and the clutter may be present which are
not easily distinguishable from the true target
measurements.
Gating and data association enable
tracking in multi sensor multi target scenario.
Gating helps in deciding if an observation (which
includes clutter, false alarms and electronic counter
measures) is a probable candidate for track
maintenance or track update and Data association
is the step to associate the measurements to the
targets with certainty when several targets are in
the same neighborhood.
2. Basic comPonents of raDar
The schematic diagram of radar in Fig. 2.� shows
its fundamental components. A transmitter
generates the radio signal with an oscillator such as
a klystron or a magnetron and controls its duration
by a modulator. A waveguide links the transmitter
and the antenna. The duplexer serves as a switch
between the antenna and the transmitter or the
receiver for the signal when the antenna is used in
both situations. Knowing the shape of the desired
received signal (a pulse), an optimal receiver can
Invited Paper
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 9
Proceedings of the National Seminar : 23 Nov 20�0
MULTI-TARGET TRACKING IN A TEST RANGE SCENARIO
R Appavu Raj
Sc ‘G’, Additional Director, Integrated Test Range, Chandipur
Abstract
Integrated Test Range (ITR) handles various types of multiple target flight trials.
To facilitate target tracking and estimation in such multi-target scenario, nearest
neighbourhood (NN) technique based data association algorithm has been adopted
at ITR. The present paper discusses the NN-based data association algorithm and its
performance in a real flight trial situation by using multiple-target track data from a
multi-target tracking radar.
1. introDUction
Integrated Test Range (ITR), Chandipur handles
test and evaluation of short, medium and long
range guided missiles, rockets and various other
air-borne objects. Ensuring safety of life and
properties in and around the launch corridor
is indispensable requirement during test and
evaluation of these developmental flight vehicles.
This necessitates real time monitoring of the flight
vehicle’s trajectory and health status with that of
the desired one. This in turn is possible with the use
of an efficient tracking and estimation algorithm
which extracts useful information from multiple
tracking sensor’s noisy measurement data for the
purpose of real time flight safety monitoring as
well as for post-flight performance analysis.
The different flight scenarios encountered
at ITR are engagement of multiple targets by
multiple missiles, ejection of multiple payloads,
engagement of air to air missiles, etc. In view of
this, the target tracking and estimation algorithm
should be capable of detecting and tracking
different targets by utilizing the measurements
from various sensors. In a multi-target tracking
situation, a single sensor or a number of sensors
can observe multiple targets at a time. Assessment
of the actual scenario in such situations becomes
complicated due to increased level of uncertainties
as opposed to single target tracking. In addition to
the presence of measurement noise of unknown
or partially known statistical properties, the source
responsible for each measurement is unknown in
this case. The situation gets further complex in
presence of false alarm & clutter and when the
number of targets is also unknown. In a dense
target scenario, it is very difficult to associate a
measurement with its source (even when each of
the targets is resolved by the sensors) with certainty.
On the other hand, the inherent limitations of the
tracking sensors may fail to resolve closely spaced
targets and thus inhibit appropriate assessment
of target scenario. Hence, the central problem
in multi-target tracking is data association, i.e.,
identifying the target responsible for individual
measurement. Further, the algorithm must have
efficient methodology for track initiation and
track deletion.
Commonly used association techniques
are distance measure, association coefficient,
correlation coefficient, probabilistic similarity
measures etc. [�]. Based on these techniques,
there are a number of algorithms for tracking
in multiple target environment [2], e.g. track
splitting approach, nearest neighbourhood
method, maximum likelihood method, Bayesian
approach etc. In track-splitting approach, a track
is split, whenever more than one detection
is observed in the neighbourhood of the
predicted measurement. The likelihood function
of each trajectory is computed and the track is
dropped when the likelihood value is less than a
predetermined threshold. Although this method
is suitable for track initiation and update, memory
and computational requirements become very
high in a dense target environment. For simplicity
as well as efficiency of the algorithm, Nearest
Neighbourhood based data association algorithm
has gained popularity. It is accomplished by
defining a measure of association that quantifies
the closeness between measurement pairs or
measurement to track pairs. There are some
difficulties in performing multi sensor tracking
due to uncertain data and disparate data
sources. The identity of the targets responsible
for each individual data set is unknown, so there
is uncertainty as how to associate data from
one sensor which are obtained at one time and
location to those of another sensor at another
point in time and location. Tracking is further
complicated by the fact that some sensors may
not observe the targets due to the variation of
signals and the sensor characteristics. Also, false
alarms and the clutter may be present which are
not easily distinguishable from the true target
measurements.
Gating and data association enable
tracking in multi sensor multi target scenario.
Gating helps in deciding if an observation (which
includes clutter, false alarms and electronic counter
measures) is a probable candidate for track
maintenance or track update and Data association
is the step to associate the measurements to the
targets with certainty when several targets are in
the same neighborhood.
2. Basic comPonents of raDar
The schematic diagram of radar in Fig. 2.� shows
its fundamental components. A transmitter
generates the radio signal with an oscillator such as
a klystron or a magnetron and controls its duration
by a modulator. A waveguide links the transmitter
and the antenna. The duplexer serves as a switch
between the antenna and the transmitter or the
receiver for the signal when the antenna is used in
both situations. Knowing the shape of the desired
received signal (a pulse), an optimal receiver can
Invited Paper
�0 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
be designed using a matched filter. Finally, the
electronic section controls all those devices and
the antenna to perform the radar scan ordered by
a software [�, 5].
3.2 Gating
This step aims at finding possible measurement
to target pairings based on the likelihood of the
predicted target position and the measurement
based on Chi-square threshold. This makes use of
state prediction covariance, innovation covariance
obtained from Kalman filter. This defines the
gate G such that the correlation is allowed if the
following relationship is satisfied:
d2 = yk S
k-�y
kT ≤ G
where, d2 = norm of measurement residual
yk = measurement residual at k-th instant
= Zk - Hx
k|k-�
Zk = actual measurement at k-th instant
xk|k -�
= predicted state at k-th instant
H = measurement matrix
S = covariance matrix of measurement residual
= HPk|k-�
HT + R
Pk|k =�
= estimation error of predicted state at k-th
instant
R = covariance matrix of measurement error
Assuming the components of measurements
(i.e. measurement in x, y and z-direction) to
be independent and measurement noise and
process noise to be zero mean and Gaussian and
independent of each other, yk becomes zero mean
and Gaussian. Hence, d2 (as defined above) being
Fig. 2. �: Radar System Schematics [�]
3. alGorithm aDoPteD at itr
Nearest Neighbourhood (NN) technique (based
on distance measure) for data association
has been adopted at ITR for the purpose of
identifying measurement-to-target pairs [�, 3].
Nearest Neighbourhood (NN) technique aims
at providing target information by resolving
targetmeasurement pairings in a multi-target
multi sensor scenario. This algorithm is based
on likelihood theory and the goal is to minimise
an overall distance function that considers
all observation to track pairings that satisfy a
preliminary gating test. As the number of targets
are not known a priori, track-oriented approach is
adopted for the present application. The different
steps of NN algorithm adopted at ITR are shown in
Fig. 3.� and are discussed below.
3.1 Data Alignment
Measurements from different sensors are available
in different sensor-specific coordinate frame, in
different data rate and w.r.t. respective sensor
locations. These data are converted into a uniform
temporal and spatial reference.
∼
∼
∼
sum of square of M (number of components of
measurements=3 in present case) independent
zero-mean unity variance Gaussian random
variable, is a random variable with Chi-Square
distribution. Assuming allowable probability of
valid observation falling outside the gate G, the
value of G can be determined by Chi-Square table
and the following relation:
Probab [ χM
2 > G ] = �- PG ,
where, PG = probability of valid observation falling
within the gate. Hence, for a particular M, the size
of gate is decided by PG and the performance of
the NN algorithm is affected by the value of PG .
3.3 Correlation
This is the process to update target
information based on the associated
measurements to the target in a situation
where either one measurement satisfies the
gate of more than one target [�], or more than
one measurement satisfies the gate of one
target, or no measurement fulfils the gating
criteria of a particular target. The process of
correlation is executed in NN by minimising
an overall distance function that considers
all measurement to track pairings that satisfy
the preliminary gating test. This way only one
measurement is used at each scan to update
information pertaining to a particular target
(in contrary to all measurements satisfying
the gate as in Probabilistic Data Association
technique [�]).
3.4 Track Update, Track Initiation
Based on the results of correlation, each of the
existing tracks is updated with the correlated
measurement. If there is any measurement
which does not satisfy gating test of any of the
existing tracks, the measurement is assumed to
be generated by a new target. Hence, a new track
is initiated based on that measurement. If there is
some existing tracks, which do not have any valid
measurements associated with them, the track
is predicted for the next time interval (without
measurement update).
Fig. 3.� : Block diagram for data association In
multi-sensor-multi-target scenario
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | ��
Proceedings of the National Seminar : 23 Nov 20�0
be designed using a matched filter. Finally, the
electronic section controls all those devices and
the antenna to perform the radar scan ordered by
a software [�, 5].
3.2 Gating
This step aims at finding possible measurement
to target pairings based on the likelihood of the
predicted target position and the measurement
based on Chi-square threshold. This makes use of
state prediction covariance, innovation covariance
obtained from Kalman filter. This defines the
gate G such that the correlation is allowed if the
following relationship is satisfied:
d2 = yk S
k-�y
kT ≤ G
where, d2 = norm of measurement residual
yk = measurement residual at k-th instant
= Zk - Hx
k|k-�
Zk = actual measurement at k-th instant
xk|k -�
= predicted state at k-th instant
H = measurement matrix
S = covariance matrix of measurement residual
= HPk|k-�
HT + R
Pk|k =�
= estimation error of predicted state at k-th
instant
R = covariance matrix of measurement error
Assuming the components of measurements
(i.e. measurement in x, y and z-direction) to
be independent and measurement noise and
process noise to be zero mean and Gaussian and
independent of each other, yk becomes zero mean
and Gaussian. Hence, d2 (as defined above) being
Fig. 2. �: Radar System Schematics [�]
3. alGorithm aDoPteD at itr
Nearest Neighbourhood (NN) technique (based
on distance measure) for data association
has been adopted at ITR for the purpose of
identifying measurement-to-target pairs [�, 3].
Nearest Neighbourhood (NN) technique aims
at providing target information by resolving
targetmeasurement pairings in a multi-target
multi sensor scenario. This algorithm is based
on likelihood theory and the goal is to minimise
an overall distance function that considers
all observation to track pairings that satisfy a
preliminary gating test. As the number of targets
are not known a priori, track-oriented approach is
adopted for the present application. The different
steps of NN algorithm adopted at ITR are shown in
Fig. 3.� and are discussed below.
3.1 Data Alignment
Measurements from different sensors are available
in different sensor-specific coordinate frame, in
different data rate and w.r.t. respective sensor
locations. These data are converted into a uniform
temporal and spatial reference.
∼
∼
∼
sum of square of M (number of components of
measurements=3 in present case) independent
zero-mean unity variance Gaussian random
variable, is a random variable with Chi-Square
distribution. Assuming allowable probability of
valid observation falling outside the gate G, the
value of G can be determined by Chi-Square table
and the following relation:
Probab [ χM
2 > G ] = �- PG ,
where, PG = probability of valid observation falling
within the gate. Hence, for a particular M, the size
of gate is decided by PG and the performance of
the NN algorithm is affected by the value of PG .
3.3 Correlation
This is the process to update target
information based on the associated
measurements to the target in a situation
where either one measurement satisfies the
gate of more than one target [�], or more than
one measurement satisfies the gate of one
target, or no measurement fulfils the gating
criteria of a particular target. The process of
correlation is executed in NN by minimising
an overall distance function that considers
all measurement to track pairings that satisfy
the preliminary gating test. This way only one
measurement is used at each scan to update
information pertaining to a particular target
(in contrary to all measurements satisfying
the gate as in Probabilistic Data Association
technique [�]).
3.4 Track Update, Track Initiation
Based on the results of correlation, each of the
existing tracks is updated with the correlated
measurement. If there is any measurement
which does not satisfy gating test of any of the
existing tracks, the measurement is assumed to
be generated by a new target. Hence, a new track
is initiated based on that measurement. If there is
some existing tracks, which do not have any valid
measurements associated with them, the track
is predicted for the next time interval (without
measurement update).
Fig. 3.� : Block diagram for data association In
multi-sensor-multi-target scenario
�2 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
4. nUmerical simUlation anD resUlts
The relevance of NN algorithm to a typical
Test Range scenario like ITR can be established
by testing and evaluating the algorithm for
different possible multi-target scenario. This is
accomplished by testing the algorithm by using
data from a multiple target tracking radar. Here,
the number of target tracked by the radar varies
at different instant of time. The algorithm does not
assume the maximum number of target tracked
by the sensor. In turn it identifies the number of
valid target within the field of view of the sensor
and estimates state of the targets by using the
noisy measurement from the sensor. Apart from
the nearest neighbourhood data association
algorithm, the algorithm uses a Kalman filter for
estimating the target state. The estimator uses
second order kinematics in Cartesian coordinates
for the target model.
The values assumed for the different
design parameters of Nearest Neighbourhood
algorithm are as given in Table 3.�. With these
parameter values the algorithm has been tested
for two different process noise levels as mentioned
above.
The track results of the algorithm for noise
standard deviation of 5-m, 50m and 5 m in x, y &
z directions respectively are shown in fig. �.�(a)-
�.�(c) and for noise standard deviation of 5m, 50m
and �0 m in x, y & z directions respectively are
shown in fig. �.2(a)-�.2(c).
It is seen from the track data of the Multi-
Target Tracking (MTT) radar that the elevation
measurement is very noisy and that has been
reflected in noisy altitude measurement data.
Although the estimation results in x and y position
is satisfactorily, the noisy altitude measurement
results in poor performance of altitude estimation.
Moreover, the noise standard deviation for the
sensor plays a major role in gating performance
(by computing the volume around the existing
track within which the measurement in the future
scans is likely to be). Fig �.2 brings out that the
larger noise standard deviation assumed in this
case results in a erroneous association result at
one instant (apparent from the track switching
between two targets near sample no. 790.
Table �.�
Distance threshold �00m
Redundant Threshold �00m
Prune Threshold 0
Chi Square Threshold 25
No. of Samples �000
Kalman Filter model for
target state estimation
Process noise standard
deviation
Measurement noise
standard deviation
Constant velocity
model with additive
white Gaussian noised
in acceleration
�0 m2/sec� and
�00 m2/sec� in two
different cases of the
study
5 m in x direction, 50m
in y direction and 5 &
�0m in z direction
5. conclUDinG remarKs
The nearest neighbourhood based data
association and target tracking algorithm has
been presented in this paper and the performance
of the algorithm has been established by using
multiple target tack data from a radar. The results
show that by judicious choice of error variances,
the algorithm performs satisfactorily to
estimate the kinematic state of all the targets
during the flight trials of multiple targets. Since
the algorithm utilizes track oriented approach,
the information regarding the number of
targets present in the scenario is not required
for execution of the algorithm. Exhaustive
sensitivity studies have been carried out for
the adopted algorithm and the results show
that the algorithm can perform unambiguously
even in the presence of false alarm and for very
closely spaced targets.
references
[�] S S Blackman, Multiple target tracking with radar applications, Artech House Inc., Norwood.
[2] Y Bar-Shalom, ‘Tracking methods in a multi-target environment’, IEEE Transaction on Automatic Control, Vol. AC-23, No. �, August, �97�.
[3] Shrabani, R Appavu Raj, ‘Multi-target Tracking in a Test Range Scenario’, Defence Science Journal, vol 57, issue 03, May 2007, ISSN-00��-7��X.
[�] L Varshney, ’Technical Report Radar System Components and System Design’, November 2002, Syracuse Research Corporation.
[5] http://en.wikipedia.org/wiki/radar
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �3
Proceedings of the National Seminar : 23 Nov 20�0
4. nUmerical simUlation anD resUlts
The relevance of NN algorithm to a typical
Test Range scenario like ITR can be established
by testing and evaluating the algorithm for
different possible multi-target scenario. This is
accomplished by testing the algorithm by using
data from a multiple target tracking radar. Here,
the number of target tracked by the radar varies
at different instant of time. The algorithm does not
assume the maximum number of target tracked
by the sensor. In turn it identifies the number of
valid target within the field of view of the sensor
and estimates state of the targets by using the
noisy measurement from the sensor. Apart from
the nearest neighbourhood data association
algorithm, the algorithm uses a Kalman filter for
estimating the target state. The estimator uses
second order kinematics in Cartesian coordinates
for the target model.
The values assumed for the different
design parameters of Nearest Neighbourhood
algorithm are as given in Table 3.�. With these
parameter values the algorithm has been tested
for two different process noise levels as mentioned
above.
The track results of the algorithm for noise
standard deviation of 5-m, 50m and 5 m in x, y &
z directions respectively are shown in fig. �.�(a)-
�.�(c) and for noise standard deviation of 5m, 50m
and �0 m in x, y & z directions respectively are
shown in fig. �.2(a)-�.2(c).
It is seen from the track data of the Multi-
Target Tracking (MTT) radar that the elevation
measurement is very noisy and that has been
reflected in noisy altitude measurement data.
Although the estimation results in x and y position
is satisfactorily, the noisy altitude measurement
results in poor performance of altitude estimation.
Moreover, the noise standard deviation for the
sensor plays a major role in gating performance
(by computing the volume around the existing
track within which the measurement in the future
scans is likely to be). Fig �.2 brings out that the
larger noise standard deviation assumed in this
case results in a erroneous association result at
one instant (apparent from the track switching
between two targets near sample no. 790.
Table �.�
Distance threshold �00m
Redundant Threshold �00m
Prune Threshold 0
Chi Square Threshold 25
No. of Samples �000
Kalman Filter model for
target state estimation
Process noise standard
deviation
Measurement noise
standard deviation
Constant velocity
model with additive
white Gaussian noised
in acceleration
�0 m2/sec� and
�00 m2/sec� in two
different cases of the
study
5 m in x direction, 50m
in y direction and 5 &
�0m in z direction
5. conclUDinG remarKs
The nearest neighbourhood based data
association and target tracking algorithm has
been presented in this paper and the performance
of the algorithm has been established by using
multiple target tack data from a radar. The results
show that by judicious choice of error variances,
the algorithm performs satisfactorily to
estimate the kinematic state of all the targets
during the flight trials of multiple targets. Since
the algorithm utilizes track oriented approach,
the information regarding the number of
targets present in the scenario is not required
for execution of the algorithm. Exhaustive
sensitivity studies have been carried out for
the adopted algorithm and the results show
that the algorithm can perform unambiguously
even in the presence of false alarm and for very
closely spaced targets.
references
[�] S S Blackman, Multiple target tracking with radar applications, Artech House Inc., Norwood.
[2] Y Bar-Shalom, ‘Tracking methods in a multi-target environment’, IEEE Transaction on Automatic Control, Vol. AC-23, No. �, August, �97�.
[3] Shrabani, R Appavu Raj, ‘Multi-target Tracking in a Test Range Scenario’, Defence Science Journal, vol 57, issue 03, May 2007, ISSN-00��-7��X.
[�] L Varshney, ’Technical Report Radar System Components and System Design’, November 2002, Syracuse Research Corporation.
[5] http://en.wikipedia.org/wiki/radar
�� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
COMPATIBILIzING ABILITY OF POLYPHOSPHAzENE AND SIC COATED MWCNTS FOR THE PEI/LCP NANOCOMPOSITES - A COMPARATIVE STUDY
Chapal Kr. Das*, Ganesh Ch. Nayak*, A. Ranjan** and A. K. Saxena**
*Materials Science Centre, IIT Kharagpur, West Bengal, India
**DMSRDE Kanpur, India
Abstract
In the present study, the effect of silicone carbide (SiC) modified multiwalled carbon
nanotube (MWCNT) and polyphosphazene, as compatibilizers, in the melt-compounded
Polyetherimide (PEI)/Liquid crystalline polymer (LCP) blend was investigated in details.
From rheological study it was evident that the viscosities of the binary and ternary
blends were lower than those of the neat polymers, indicating a synergistic effect of
LCP in reducing the melt viscosity and also signifying its great ability as a processing
aid. Scanning electronic microscopic (SEM) observation had revealed that the addition
of polyphosphazene and modified MWCNT, together, results in a decrease in average
disperse domain size of LCP phase and leading to the improved filler-matrix adhesion.
Measurement of surface energy from contact angle measurements also point towards
the improved interfacial interaction, in presence of compatibilizers.
Keywords: MWCNT , Polyphosphazene, SiC coating, PEI, LCP.
1. introduction
Blending of liquid crystalline polymers (LCPs) with
thermoplastics has attracted considerable interest
for many reasons. One of these is that, under
appropriate conditions, the LCP phase can be
deformed into the fiber form, leading to so-called
in situ composites.[�–�] Secondly, addition of a
small amount of LCPs to the thermoplastics may
result in a considerable reduction in the blend melt
viscosity, thereby improving the processability
of engineering plastics.[5-7] However,
incompatibility between thermoplastic and LCPs
is an issue of major concern and this lacuna need
to be addressed in such a way that, we can achieve
polymer blends having superior mechanical,
thermal, and morphological properties. One way
to solve the afore¬mentioned problem is to use
of a compatibilizer. In recent years a large amount
of research focused on the compatibilization of
LCP blends has been published. [�-��] Baird et
al. used functionalized polypropylene, MAH-g-
PP, as a compatibilizer for the polypropylene/
LCP blends and they found improved interfacial
adhesion due to some specific interactions like
hydrogen bonding.[��-�3] Seo demonstrated
the Compatibilization of PA6/vectra B950, PA�6/
Vectra B950, PBT/Vectra A950 blends by MAH-g-
EPDM.According to Seo, some chemical reaction
between MAH groups and LCP were responsible
for the compatibilization.[��-��]. In the previous
works done at our laboratory, we had explored
the effectiveness of polyphosphazene as a
compatibilizer for the PES/LCP [�9], PEI/LCP[20]
and Nylon/LCP[2�] blends. We found that
incorporation of polyphosphazene reduced
the particle size of the LCP domains indicating
towards the improvement of compatibility
between the blend partners. We had also studied
the effect of SiC coated MWCNTs on the properties
of ABS/LCP[22] blend and improvement in the
dispersion of modified MWCNTs was noticed in
the blend matrix as compared to pure MWCNTs.
In the present work, an attempt has been made to
explore the combine effect of polyphosphazene
and SiC coated MWCNTs on the thermal,
morphology and interfacial property of PEI/LCP
blends. The goal of this study is to interpret the
effectiveness of polyphosphazene and SiC coated
MWCNT, as compatibilizer, for PEI/LCP blend.
2. experimental section:
2.1 Materials Used:
Polyetherimide (PEI), (Ultem �0�0), was
obtained from General Electric Company. Liquid
crystalline polymer (Vectra A950) was supplied by
Ticona, USA. This LCP is wholly aromatic copolyester
containing 25 mol% of 2, 6-hydroxynaphthoic acid
(HNA) and 75 mol% of p-hydroxybenzoic acid (HBA).
Polyphosphazene which has been used in
this research work was made by us in the laboratory
of applied chemistry division, DMSRDE, Kanpur,
India. Polyphosphazene used in this research
work are having inorganic backbone skeletal
(P=N) with various organic pendant groups. The
chemical structures of the components used, are
given in figure �.
The MWCNTs (MWCNTs-�000) were from
IIjin Nano Technology, Korea. The diameter, length
and aspect ratio were �0–20 nm, 20 µm and ~�000,
respectively. The density of MWCNT is 2.�6 g/cm3.
Figure 1: Chemical structure of PEI, LCP and
Polyphosphazene
2.2 Modification of MWCNT with silicon carbide
(SiC)
The procedure for modification is as
follows [22]:
i. Solid-state polycarbosilane (PCS) (Indigenously made
by DMSRDE, Kanpur, Mw ~ ��00) is put in a beaker
containing 50 ml of n-hexane, and ultrasonically
dissolved using a horn type ultrasonicator.
ii. Then, the MWCNTs (IIjin Nano Technology,
Korea.) are introduced to the PCS solution and
then ultrasonically dispersed for 30 min at 60oC.
The weight ratio of PCS/ MWCNTs was 3/7.
Invited Paper
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �5
Proceedings of the National Seminar : 23 Nov 20�0
COMPATIBILIzING ABILITY OF POLYPHOSPHAzENE AND SIC COATED MWCNTS FOR THE PEI/LCP NANOCOMPOSITES - A COMPARATIVE STUDY
Chapal Kr. Das*, Ganesh Ch. Nayak*, A. Ranjan** and A. K. Saxena**
*Materials Science Centre, IIT Kharagpur, West Bengal, India
**DMSRDE Kanpur, India
Abstract
In the present study, the effect of silicone carbide (SiC) modified multiwalled carbon
nanotube (MWCNT) and polyphosphazene, as compatibilizers, in the melt-compounded
Polyetherimide (PEI)/Liquid crystalline polymer (LCP) blend was investigated in details.
From rheological study it was evident that the viscosities of the binary and ternary
blends were lower than those of the neat polymers, indicating a synergistic effect of
LCP in reducing the melt viscosity and also signifying its great ability as a processing
aid. Scanning electronic microscopic (SEM) observation had revealed that the addition
of polyphosphazene and modified MWCNT, together, results in a decrease in average
disperse domain size of LCP phase and leading to the improved filler-matrix adhesion.
Measurement of surface energy from contact angle measurements also point towards
the improved interfacial interaction, in presence of compatibilizers.
Keywords: MWCNT , Polyphosphazene, SiC coating, PEI, LCP.
1. introduction
Blending of liquid crystalline polymers (LCPs) with
thermoplastics has attracted considerable interest
for many reasons. One of these is that, under
appropriate conditions, the LCP phase can be
deformed into the fiber form, leading to so-called
in situ composites.[�–�] Secondly, addition of a
small amount of LCPs to the thermoplastics may
result in a considerable reduction in the blend melt
viscosity, thereby improving the processability
of engineering plastics.[5-7] However,
incompatibility between thermoplastic and LCPs
is an issue of major concern and this lacuna need
to be addressed in such a way that, we can achieve
polymer blends having superior mechanical,
thermal, and morphological properties. One way
to solve the afore¬mentioned problem is to use
of a compatibilizer. In recent years a large amount
of research focused on the compatibilization of
LCP blends has been published. [�-��] Baird et
al. used functionalized polypropylene, MAH-g-
PP, as a compatibilizer for the polypropylene/
LCP blends and they found improved interfacial
adhesion due to some specific interactions like
hydrogen bonding.[��-�3] Seo demonstrated
the Compatibilization of PA6/vectra B950, PA�6/
Vectra B950, PBT/Vectra A950 blends by MAH-g-
EPDM.According to Seo, some chemical reaction
between MAH groups and LCP were responsible
for the compatibilization.[��-��]. In the previous
works done at our laboratory, we had explored
the effectiveness of polyphosphazene as a
compatibilizer for the PES/LCP [�9], PEI/LCP[20]
and Nylon/LCP[2�] blends. We found that
incorporation of polyphosphazene reduced
the particle size of the LCP domains indicating
towards the improvement of compatibility
between the blend partners. We had also studied
the effect of SiC coated MWCNTs on the properties
of ABS/LCP[22] blend and improvement in the
dispersion of modified MWCNTs was noticed in
the blend matrix as compared to pure MWCNTs.
In the present work, an attempt has been made to
explore the combine effect of polyphosphazene
and SiC coated MWCNTs on the thermal,
morphology and interfacial property of PEI/LCP
blends. The goal of this study is to interpret the
effectiveness of polyphosphazene and SiC coated
MWCNT, as compatibilizer, for PEI/LCP blend.
2. experimental section:
2.1 Materials Used:
Polyetherimide (PEI), (Ultem �0�0), was
obtained from General Electric Company. Liquid
crystalline polymer (Vectra A950) was supplied by
Ticona, USA. This LCP is wholly aromatic copolyester
containing 25 mol% of 2, 6-hydroxynaphthoic acid
(HNA) and 75 mol% of p-hydroxybenzoic acid (HBA).
Polyphosphazene which has been used in
this research work was made by us in the laboratory
of applied chemistry division, DMSRDE, Kanpur,
India. Polyphosphazene used in this research
work are having inorganic backbone skeletal
(P=N) with various organic pendant groups. The
chemical structures of the components used, are
given in figure �.
The MWCNTs (MWCNTs-�000) were from
IIjin Nano Technology, Korea. The diameter, length
and aspect ratio were �0–20 nm, 20 µm and ~�000,
respectively. The density of MWCNT is 2.�6 g/cm3.
Figure 1: Chemical structure of PEI, LCP and
Polyphosphazene
2.2 Modification of MWCNT with silicon carbide
(SiC)
The procedure for modification is as
follows [22]:
i. Solid-state polycarbosilane (PCS) (Indigenously made
by DMSRDE, Kanpur, Mw ~ ��00) is put in a beaker
containing 50 ml of n-hexane, and ultrasonically
dissolved using a horn type ultrasonicator.
ii. Then, the MWCNTs (IIjin Nano Technology,
Korea.) are introduced to the PCS solution and
then ultrasonically dispersed for 30 min at 60oC.
The weight ratio of PCS/ MWCNTs was 3/7.
Invited Paper
�6 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
iii. The resultant suspension is then dried naturally
in a draft chamber at 25oC in order to remove
n-hexane.
iv. Then, the PCS–MWCNTs mixture is put into a
quartz crucible and is cured at 2�0oC for 90
minutes under an oxidizing atmosphere, in
order to prevent agglomeration of PCS during
subsequent high temperature treatments.
v. Finally, the product obtained in the previous
step is heat-treated at ��50oC in oven for one
hour in argon atmosphere.
2.3 Preparation of composites
Prior to mixing PEI and LCP and polyphosphazene
are dried under vacuum at �0 oC and MWCNTs
at 200 oC for �2 hours. PEI/LCP composites with
polyphosphazene and SiC modified MWCNTs
are prepared by melt blending in a sigma high
temperature internal mixture equipped with two
Sigma type counter rotating rotors. The blending
compositions were presented in the table �.
Blending is carried out at 330 oC and �00 rpm. One
set of pure PEI/LCP binary blend also prepared by
the same route for comparison. Samples for the
mechanical testing are prepared by compression
molding at 350 oC using �0 MPa pressure and
then allowed to cool to room temperature.
3. characterization
3.1 Scanning electron Microscopy (SEM)
The fractured surface of the blend
systems were analyzed by using a Tescan VEGA
LSU SEM. Before the analysis the fractured surfaces
were sputtered with gold for making the surface
conducting.
3.2 Rheology
Rheology study is carried out in a Capillary
Rheometer (Smart RHEO �000, CEAST) at 330oC, at
different shear rates, to investigate the effect of
polyphosphazene and modified MWCNTs on the
viscosity of PEI/LCP blend.
3.3 Mechanical Properties
Tensile tests are carried out on dumb-bell
shaped samples using a Hounsfield HS �0 KS (universal
testing machine) operated at room temperature with
a gauge length of 35 mm and crosshead speed of
5mm/min. Tensile values reported here are an average
of the results for tests run on at least four specimens.
3.4 Thermogravimetric Analysis (TGA)
Thermogravimetric analysis curves were
recorded with a Dupont 2�00 thermogravimetric
analyzer. The TGA measurements were conducted
with a heating rate of �0oC/min under air
atmosphere from �00 to 650oC.
4. results and Discussion
4.1 Morphological Study
The fracture surfaces of binary and ternary
blends were investigated using SEM and the
images were presented in figure 2(a-d). Figure 2a
depicted the SEM micrograph of PEI/LCP (B) binary
blend system. It showed that, spherical domains
Table 1: Sample codes and formulation of
nanocomposites
Sample PEI LCP Polyphosphazene MWCNT
Code (Wt%) (Wt%) (Wt%) (Wt%)
A �00 - - -
B 75 25 - -
C 75 22.5 2.5 -
D 75 22.5 - 2.5
E 75 20 2.5 2.5
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �7
Proceedings of the National Seminar : 23 Nov 20�0
of LCPs were distributed in the PEI matrix with an
average particle size of �.02 µm (measured using
the VEGA LSU SEM software). The voids shown
in the Figure 2a were formed due to the pullout
of the LCP phase from the PEI matrix, indicating
towards the poor adhesion at the interface of
PEI and LCP. Addition of polyphosphazene to the
PEI/LCP blend reduced the average particle size of
LCP to 6.27 µm and a reduction in the LCP pullouts
also observed, as compared to PEI/LCP blend
system. This indicates towards the improvement of
interfacial adhesion at the PEI/LCP interface due to
the compatibilization effect of polyphosphazene
(Figure 2b). However, incorporation of SiC¬modified
MWCNTs (D) showed further reduction in the
average particle size (5.62 µm, which is clear from
Figure 2c) suggesting a better interfacial adhesion
at the interface.
The difference between the blend systems
with polyphosphazene (sample C) and with SiC
coated MWCNTs (sample D), was the shape of the LCP
domains and the fibrillation of LCP. The system with
polyphosphazene showed spherical domains of LCP
without any LCP fibrillation while the system with SiC
coated MWCNTs shows slight deformation of the LCP
domains to ellipsoidal form with a little fibrillation
on there surfaces. We proposed a mechanism for the
above observed morphology as follows:
Since PEI and LCP were incompatible with each
other, during melt blending there will be a
slippage between the two phases (due to the
poor adhesion at the interface) which reduces the
chances of LCP deformation to form fibers out of
it. Due to this reason, only spherical domains of
LCPs were formed in the binary blend system. The
voids observed in the fracture surface of binary
blend were formed by the pullout of LCP domains
during fracture process. In the ternary blend C,
polyphosphazene was acting as a compatibilizer
between the blend partners and hence step up
the interfacial adhesion due to which the LCP
domains were broken into smaller particles and
average particle size was reduced. However, in the
SiC coated MWCNTs added system the nanotubes
might acting as a bridging agent between the
two phases and hence helped in dragging the
LCP phase along the flow direction, during mixing,
which deform the spherical LCP domains to
slightly ellipsoidal form. The rougher surface of SiC
coated MWCNTs decreased the slippage of these
modified MWCNTs at the interface and hence
slight fibrillation was observed in these samples. If
this proposed mechanism is true then addition of
both polyphosphazene and SiC coated MWCNTs
to the PEI/LCP blend should give rise to more
fibrillation in the system due to the combined
effect of polyphosphazene and SiC coated
MWCNTs. The above mentioned inference was
found in figure 2d. As we can see the LCP domains
were completely fibrillated for the system E.
(a) (b) (c) (d)
Figure 2: SEM image of (a) PEI/LCP, (b) PEI/LCP/Polyphosphazene, (c) PEI/LCP/SiC coated MWCNTs and (d) PEI/LCP/SiC coated MWCNTs /Polyphosphazene blends
�� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
4.2 Rheological Study
The flow properties of pure PEI, and its
respective blends (B, C, D, and E) were investigated
at 330oC using a capillary rheometer. The viscosity–
shear rate relationship for the pure PEI and the
blends were shown in Figure 3. The viscosities of
the binary and the ternary blends were found to
be lower than that of the pure PEI, which indicating
towards the ability of LCP as a processing aid in
these blend systems. The binary blend of PEI/
LCP is having the lowest viscosity among all the
blend systems which may be due to the following
factors i. The incompatibility between the two phases
gives rise to interlayer slippage between the PEI and LCP phases and hence reducing its viscosity.[23]
ii. Under the shear force (in the capillary rheometer) the LCP domains might align in the direction of the flow and hence enhance the
melt flow and reduce the melt viscosity.
modified MWCNTs which is due to presence of
these modified MWCNTs at the interface of PEI and
LCP and acting as a bridging agent between the
two phases. We had found in our previous work
[22] that the coating of SiC makes the MWCNTs
surface rougher which restricts the slippage of
these modified nanotubes from the polymer
matrix. The same phenomenon might also occur
at the interface of PEI and LCP where nanotubes
reduced the chain slippage at the interface which
increases the viscosity of the PEI/LCP/SiC coated
MWCNTs blend system. However the distribution
of SiC coated MWCNTs in bulk also can increase
the viscosity. But viscosity of blend system with
both polyphosphazene and SiC coated MWCNTs
appears to be the lower than the blends with only
polyphosphazene and SiC coated MWCNTs. This is
due to the formation of LCP fibers during mixing
which were aligned along the flow direction and
reduces the viscosity of this blend system in the
capillary rheometer analysis.
4.3 Mechanical Properties
Variations in mechanical properties of pure matrix
along with the blends were shown in Figure
�a&b. In binary blend system (B), tensile strength
decreases as compared to pure PEI matrix (A),
indicating the poor adhesion between the matrix
phase and dispersed phase. In case of PEI/LCP/
polyphosphazene blend system (C), the tensile
strength, and tensile modulus was found to be
increase in comparison to PEI/LCP blend system
(B) suggesting an enhancement of interfacial
adhesion between the PEI and LCP matrix which
helps in the stress transfer from the PEI phase to
the LCP phase and thus improves both tensile
strength and modulus of the blend. However,
the elongation at break has also increased with
Figure 3: Rheological properties of pure PEI and its blends with LCP
The polyphosphazene compatibilized
blend exhibits a rise in viscosity, in comparison
to uncompatilized binary blend because of the
restricted interlayer slippage between the PEI
and LCP phase, by the presence of compatibilizers
at the interface. The rise in viscosity is most
pronounced in case of PEI/LCP blend with SiC-
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �9
Proceedings of the National Seminar : 23 Nov 20�0
the addition of polyphosphazene indicating the
plasticizing effect of polyphosphazene in making
the blend flexible in nature. The tensile strength,
and modulus of PEI/LCP/SiC-modified MWCNTs (D)
blend system showed higher value in comparison
to PEI/LCP blend system but elongation at break
had followed the usual way, i.e., it was decreased
for the PEI/LCP/2.5 wt% SiC-modified MWCNT
composites. The probable reasons behind this
enhancement in tensile strength and modulus are
as follows [2�]: (i) Bridging effect of SiC coated MWCNTs at the PEI
and LCP interface (discussed in the morphology section), which requires more energy to pull out the LCP phase and thus resists the fracture which increased the tensile strength.
(ii) Presence of SiC coated MWCNTs in the bulk matrix enhanced the stress transfer from the matrix to the MWCNTs hence improves the modulus.
However, for combine addition of SiC
coated MWCNTs and polyphosphazene to the PEI/
LCP blend (E) shows a synchronous improvement
in strength and modulus. The enhancement in
tensile strength may be ascribed to the mechanical
reinforcement offered by SiC-modified MWCNTs.
4.4 Thermal Stability
Thermal stability of the composites is
graphically represented in Figure 5. As showed in
the figure 5, binary blend of PEI/LCP (B) followed a
two-step degradation process at �52oC and 527oC.
Addition of 2.5% of polyphosphazene (C) and
SiC modified MWCNTs (D) to the PEI/LCP blend
increased the first onset degradation temperature
to �70 and �7�oC respectively, which suggested
that the polyphosphazene and SiC modified
MWCNTs aided blend systems were more thermal
stable as compared to the uncompatibilized
blend system (B). However, addition of both SiC
modified MWCNTs and polyphosphazene to the
PEI/LCP blend (E), improved the thermal stability
of the composite to �9�oC. The superior thermal
stability of E can be apparently attributed to the
restricted motion of polymer chains due to SiC
modified MWCNTs [25] and compatibilization
effect of polyphosphazene between the PEI matrix
and dispersed LCP phase. [20]
(b)
(a)
Figure 4: Tensile properties of different PEI/LCP blend
systems (a)Tensile Modulus and (b) Tensile Strength Figure 5: TGA analysis of pure PEI and its blends with LCP
20 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
5. conclusions
Ternary blends of PEI/LCP with
polyphosphazene and SiC modified MWCNTs
were prepared by melt blending. Rheological
study confirms that viscosity of ternary blends
exhibit higher value in comparison to binary
blend system. Combination of polyphosphazene
and SiC modified MWCNTs in PEI/LCP blend has
improved the tensile strength and tensile modulus
as compared to binary and ternary blends as well
as pure PEI. In presence of polyphosphazene,
reduction in number average particle size of LCP
was observed as compared to PEI/LCP binary
blend. SEM study reveals that the fibrillation of
LCP in presence of SiC modified MWCNTs and
polyphosphazene.
6. references
[�] Kiss G. Polym. Eng. Sci. �9�7; 27:��0-�23. [2] Handlos V, Baird D G. J. Macromol. Sci. Rev. C. �995;
35(2):��3-23�. [3] Crevecour G., Groeninckx G. Polym Comp.�992; �3
(3):2��-250. [�] Seo Y, Kim B, Kwak S, Kim K U, Kim J. Polym. �999;
�0 (�6): ����-��50. [5] Kohli A., Chung N, Weiss A R. Polym Eng Sci.
�9�9;29:573. [6] Croteau J F, Laivins G V. J. of App. Poly. Sci. �990;39:
2377. [7] Malik T Q, Carreau P J, Chaplean N. Polym Eng Sci.
�9�9;29:600. [�] Seo Y, Hong S M., Hwang S S, Park T S, Kim K U, Lee
S Lee. J. Polymer.�995; 36:5�5. [9] Yongsok S, Soon M H, Kwang U K. Macromolecules.
�997;30: 297�. [�0] Dutta D, Weiss R.A. Polym. Compos. �992; �3:39�. [��] Datta A., Chen H.H., Baird D G. Polymer.
�993;3�:759. [�2] Datta A, Baird D G, Polymer. �995;36:505.
[�3] O’Donnell H J, Baird D G. Polymer. �995;36:3��3. [��] Seo Y, J Appl Polym Sci. �997;6�:359. [�5] Seo Y, Hong S M, Kim K U. Macromolecules.
�997;30:297�. [�6] Seo Y, Kim K U. Polym Engg Sci. �99�;3�:5�3. [�7] Seo Y. J Appl Polym Sci. �99�;70:�5�9. [��] Seo Y, Kim B, Kim K U. Polymer. �999;�0:���3. [�9] Bose S, Mukherjee M, Das C K, Saxena A K. Polymer
Composites. 2009;3�:5�3. [20] Bose S, Pramanik N, Das C K, Ranjan A, Saxena A K.
Materials and Design. 2009;3�:����. [2�] Bose S, Mukherjee M, Rath T, Das C K. J Reinf plast
Comp. 2009;2�: �57. [22] Bose S, Mukherjee M, Pal K, Nayak G C, Das C K.
Polym Advan Technol.2009:2�:272. [23] Utarcki L A, Kamal MWCNTs R. Polymer Blends
Handbook Vol.�. Netherlads: Kluwer Academic publisher; 2002.
[2�] Sachariades A, Porter P S. High Modulus Polymer. New York: Marcel Dekker;�9��.
[25] Lozano K, Barrera E V. J. Appl Polym Sc. 200�;79:�25.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 2�
Proceedings of the National Seminar : 23 Nov 20�0
MATERIALS FOR BALLISTIC APPLICATIONS
Basudam Adhikari
Materials Science Centre, Indian Institute of Technology, Kharagpur 72�302
E. Mail: [email protected]
Prior to the development of synthetic polymers,
metals and ceramics were the classical materials
for battlefield devices till the World War II. War
situations in �9�0s compelled the superpowers to
develop technologies for manufacturing synthetic
polymers especially synthetic rubbers and other
high performance polymers. Revolutionary
research on polymers exploded in two decades
following the World War II in American and
European countries and the result is the success
in polyolefin technology and the award of Noble
Prize to ziegler and Natta. Beyond �970s there is an
outburst of technological development in polymers
including other strategic materials. Polymers with
high strength, toughness and thermal stability
have been developed. Nanocomposites are
stronger, creating greater durability and requiring
less total material. It has been established that
nanotechnology will produce a host of advanced
materials with unprecedented strength and
versatility. Although polymeric materials produce
relatively soft devices but metals and ceramics are
also used in combination to obtain a balance of
ultimate performance. Since ballistic armor uses a
host of polymers, ceramics and metals an overview
of application of these materials is presented in
this lecture.
A ballistic vest, bulletproof vest or bullet-
resistant vest is an item of personal armor to
absorb the impact from firearm-fired projectiles
and shrapnel from explosions. In ballistic vest
layers of very strong fiber are used. In fact a
bullet is caught, deformed and mushroomed
into a dish shape, and its force is spread over a
larger portion of the vest fiber. The vest absorbs
the energy from the deforming bullet, bringing it
to a stop before it can completely penetrate the
textile matrix. On the contrary vests designed
for bullets are not suitable for sharp weapons
such as knives, arrows, etc. due to concentrated
impact force, which punctures the fiber layers of
the vest fabric. As a measure of extra protection
sometimes textile vests are supported with
metal (steel or titanium), ceramic or polyethylene
plates. Vests which are designed specifically
against bladed weapons and sharp objects may
incorporate coated and laminated para-aramid
textiles or metallic components.
Invited Paper
22 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
research Progress in Ballistic Vests
Advances in material science have opened the
door for bulletproof vest to stop handgun and
rifle bullets with a soft textile vest, viz., Kevlar
without additional metal or ceramic plating.
The para-aramids have not progressed beyond
the limit of 23 grams per denier in fiber tenacity.
Improvements in ballistic performance have also
been made by UHMWPE fiber. The basic fiber
properties have been improved to the 30–35
g/d range. The major ballistic performance of
poly-p-phenylenebenzobisoxazole (PBO) fiber
is also known [Tooru Kitagawa, Hiroki Murase,
Kazuyuki Yabuki, Morphological Study on Poly-p-
phenylenebenzobisoxazole (PBO) Fiber, Journal of
Polymer Science: Part B: Polymer Physics, Vol. 36,
39–�� (�99�)]. This fiber permitted the design of
handgun soft armor that was 30–50% lower in
mass as compared to the aramid and UHMWPE
fibers.
Spider silk fibers spun from soluble
recombinant silk produced in mammalian cells is
considered as a second generation “super” fibers
although the science of this material is complex.
Spider dragline silk is a flexible, lightweight
fiber of extraordinary strength and toughness
comparable to that of synthetic high-performance
fibers. The process of spider silk production was
biomimicked by expressing the dragline silk
genes (ADF-3/MaSpII and MaSpI) of two spider
species in mammalian cells and produced soluble
recombinant (rc)-dragline silk proteins with
molecular masses of 60 to ��0 kilodaltons. The
wet spinning of silk monofilaments spun from
a concentrated aqueous solution of soluble rc-
spider silk protein (ADF-3; 60 kilodaltons) was
done. The water insoluble spun fibers had a �0
to �0 µm diameter and toughness and modulus
values comparable to those of native dragline
silks but with lower tenacity. Further research aims
to develop artificial spider silk which could be
super strong, yet light and flexible. Simultaneous
research is underway to harness nanotechnology
to help create super-strong fibers that could be
used in future bulletproof vests [Anthoula Lazaris,
Steven Arcidiacono, Yue Huang, Jiang-Feng zhou,
François Duguay, Nathalie Chretien, Elizabeth A.
Welsh, Jason W. Soares, Costas N. Karatzas, Spider
Silk Fibers Spun from Soluble Recombinant Silk
Produced in Mammalian Cells, Science 295 (555�):
�72–�76].
A new type of carbon fibre, developed at
the University of Cambridge is reported. This fiber
could be woven into super-strong body armour for
the military and law enforcement. The inventors of
this fiber claimed that this material is several times
stronger, tougher and stiffer than fibres currently
used to make protective armour. The lightweight
fibre, made up of millions of tiny carbon nanotubes,
is also known to reveal exciting properties. Carbon
nanotubes are hollow cylinders of carbon just one
atom thick. This material was developed by Alan
Windle et al. (Science, 2007) at the Department of
Materials Science and Metallurgy at University of
Cambridge. Windle claimed that these nanotube
fibers can be woven as a cloth, or incorporated
into composite materials to produce super-strong
products, i.e., very strong, lightweight and good
at absorbing energy. This fibre is someway better
than the existing high performance Kevlar fibres.
It appears that this new material can also find
applications in the area of hi-tech “smart” clothing,
bomb-proof refuse bins, flexible solar panels, and,
eventually, as a replacement for copper wire in
transmitting electrical power and signals.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 23
Proceedings of the National Seminar : 23 Nov 20�0
A high performance M5 fiber based on the
rigid-rod polymer poly [diimidazo pyridinylene
(dihydroxy) phenylene] was developed for
ballistics / structural composites [Cunniff, Philip
M.; Auerbach, Margaret; Vetter, Eugene; Sikkema,
Doetze J. High Performance “M5” Fiber for
Ballistics/Structural Composites, http://web.mit.
edu/course/3/3.9�/OldFiles/www/slides/cunniff.
pdf.]. The ballistic impact potential of this fiber-
based armor system was estimated using an
“armor materials by design” model for personnel
armor. The model was based on a dimensional
analysis of the mechanical properties of the
fibers used to construct the armor system. The
performance of these armor systems was found
to be exceptional.
textile wovens and laminates research
Finer yarns and lighter woven fabrics are key
factors in improved ballistic performances.
Decreasing the yarn size increases the cost of
ballistic fiber. The current practical limit of fiber
size is 200 denier with most woven fabrics limited
at the �00 denier level. A study on the ballistic
impact characteristics of Kevlar woven fabrics
impregnated with a colloidal shear thickening fluid
[Young S. Lee, E. D. Wetzel N. J. Wagner, The ballistic
impact characteristics of Kevlar woven fabrics
impregnated with a colloidal shear thickening
fluid, Journal of Materials Science, 3� (2003)
2�25 – 2�33] reports the ballistic penetration
performance of a composite. The composite is
made of woven Kevlar fabric impregnated with a
colloidal shear thickening fluid (silica particles (�50
nm) dispersed in ethylene glycol). The composite
exhibited penetration resistant characteristics.
Ballistic penetration measurements at 2�� m/s
were performed to demonstrate the efficacy of
this composite. A significant enhancement in
ballistic penetration resistance was demonstrated.
The reason was due to the addition of shear
thickening fluid to the fabric, without any loss in
material flexibility.
Developments in ceramic armor
The use of small ceramic components is an area
of special activity pertaining to vests. Ceramic
materials, their processing and progress in ceramic
penetration mechanics have been identified as
significant areas required for ceramic armor. While
large torso sized ceramic plates are complex to
manufacture as well as subject to cracking in
use, monolithic plates also have limited multi hit
capacity as a result of their large impact fracture
zone. These have become the motivations for new
types of armor plate comprising new designs of
2 and 3 dimensional arrays of ceramic elements
that can be rigid, flexible or semi-flexible. The
manufacture of array type systems with flex,
consistent ballistic performance at edges of ceramic
elements is an active area of research. A ceramic
armor material database has been reported [T. J.
Holmquist; A. M. Rajendran; D. W. Templeton; K. D.
Bishnoi; http://www.stormingmedia.us /62/6292/
A629263.html]. Experimental data obtained from
numerous journals and conference proceedings
have been reported. The data on nine different
ceramic materials are presented. The ceramics are:
silicon carbide, boron carbide, titanium diboride,
aluminum nitride, silicon nitride, aluminum
oxide (�5% pure), aluminum oxide (high purity),
tungsten carbide and glass. For each ceramic
material experimental data are presented based
on: mechanical tests, hydrostatic tests, plate
2� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
impact tests, semi-infinite penetration tests, depth
of penetration (DOP) tests, perforation tests and
other tests.
nanomaterials in ballistics
With the progress in nanotechnology a number
of methods are being implemented incorporating
nanomaterials in body armor production. One
good example is the use of shear thickening fluids
(silica particles (�50 nm) dispersed in ethylene
glycol) in woven Kevlar fabric. The suit produced in
this way is rigid enough to protect the wearer as
soon as a kinetic energy threshold is surpassed. In
another development it was demonstrated that
a nanocomposite based on tungsten disulfide
nanotubes was able to withstand shocks generated
by a steel projectile traveling at velocities of up to �.5
km/s. The material was also reported to withstand
shock pressures generated by the impacts of up to
250 MT-force/cm2 (2�.5 GPa; 3,550,000 psi). During
the tests, the material proved to be so strong that
after the impact the samples remained essentially
unmarred. A recent study in France tested the
material under isostatic pressure and was found to
be stable up to at least 3� GPa. In mid-200�, spider
silk bulletproof vests and nano-based armors were
developed for potential market release. Both the
British and American militaries have desired to use
woven carbon fiber fabric from carbon nanotubes
that was developed at University of Cambridge for
use as body armor.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 25
Proceedings of the National Seminar : 23 Nov 20�0
DOPING IN SEMICONDUCTOR NANOCRYSTALS
Narayan Pradhan
Department of Materials Science
Indian Association for the Cultivation of Science
Jadavpur, Kolkata 700032, India
Email: [email protected]
Abstract:
Light emitting semiconductor nanocrystals (quantum dots or Q-dots) have been
attracting interest over the last two decades in view of enormous technological
possibilities in various fields, particularly in the field of display or lighting devices and
in biological labelling or diagnostic. These are the direct band gap semiconductor
nanocrystals where the exciton of the nanocrystals recombines within the valence and
conduction bands of the nanocrystals and provides size dependent tunable emission.
In recent progress, doped semiconductor nanocrystals are emerged as new series of
nanocrystal emitters which are not only intense but also associated with several other
advantages i.e. larger Stoke shift, minimized self-absorption, thermal and environmental
stability etc. These nanocrystals are made by doping different transition metal ions in
semiconductor host nanocrystals which allows the host exciton to recombine by this/
these additional energy state/s. A detail study of the doping, particularly the emission
properties and its comparison with undoped nanocrystals are presented in this
manuscript.
introduction:
Semiconductor nanocrystals with size tunable
optical emissions�-3 have been extensively studied
as light emitting source for LEDs,� lasers,5 bar-
coding,6 biological labeling2,7 and chemical
sensing� etc. These highly emissive nanocrystals
with tunable, narrow and stable emission are
mostly direct band gap inorganic semiconductors
where the generated exciton relaxes within their
valance and conduction bands.�-3, 9 Apart from this
direct exciton relaxation, introducing additional
impurity or dopant states in between the
valance and conduction band diverts the exciton
relaxation process through these additional
energy states leading to intense dopant related
Invited Paper
26 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
emission at host excitations.�0-�6 These dopant
related emission compete with tunable exciton
emission for the comparable intensity, stability�7
and other related photo-physical aspects for
different applications.��,�9
The photo-physical properties and
particularly the choice of the exciton of the
nanocrystals to select the allowed path for
recombination when more than one possible
channel is present remained important to govern
the optical properties of nanocrystals. Among
different transition metal ions dopants Mn and
Cu are the well studied one and provide stable,
tunable and bright emission. �0-�6 Similarly, a
larger number of hosts both in group II-VI and
group III-V semiconductor nanocrystals can be
chosen to provide the excitation. znSe, znS and
alloy of CdznS, having well established synthetic
protocols have been explored for doping either
Mn or Cu to provide different emissions.�0-�2 Figure
� shows the emission color (images) of undoped
znSe and three different emissions in longer
wavelength but in visible window on doping
Mn and Cu ions. This spectacular change of light
emission attracts researcher to understand the
novelty of the synthesis as well as the new photo-
physical properties.
The appropriate condition to allow
the exciton to relax via the dopant states is the
selection of hosts which should have high band
gap and should accommodate these dopant states
within their valence and conduction bands. Figure
2 shows the schematic presentation of the band
structure of a semiconductor and the possible
existence of Cu and Mn states. Mn provides its two
excited states in between the host band gap, and
both hole and electron of the host exciton migrate
to Mn states.�0-�2 The recombination within these
Mn states provides the orange emission. This
emission, as it depend on the Mn bands remains
mostly non-tunable with tuning the size and
composition of hosts. But there are several reports
of small range tuning because of the interaction of
ligands on the crystal field of Mn (d5).�2 However,
Cu follows a different mechanism. Even though
the exact origin of Cu emission is not yet known
but the widely acceptable mechanism suggests
that Cu provides t2 states just above the valance
band of the host nanocrystals and only the hole
of the host exciton migrates to these states.20, 2�
The recombination occurs within the electron in
the conduction band of the host nanocrystals and
the hole in Cu states, and hence the emission is
expected tunable as the conduction band of the
host tunes with tuning size and composition of
the nanocrystals.
Figure 1. Digital images from the reaction flasks of ZnSe and after doping with Copper, Manganese and Manganese with sulphur. Undoped ZnSe emits blue and doping with Cu provides tunable emission and green is the best one. Doping with Mn, ZnSe emits yellow and in presence of additional ligand (S), the yellow emission changes to red. Excitation wavelength is 365 nm. The UV lamp used has power 6 mw.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 27
Proceedings of the National Seminar : 23 Nov 20�0
nanocrystals where the excitation band overlaps
with the emission band, in that case the emission
energy again used to excite the nanocrystals. When
the concentration of the sample increases, it is more
pronounced.22 This is a disadvantage characteristic
as while these nanocrystals are used for making
a device where larger number of materials are
used, in that case the overall emission decreases
with increase of nanocrystal concentration. In
undoped quantum dots, this happens and hence
to explore nanocrystal emitters for making device,
nanocrystals should have minimized or no self-
absorption i.e. should have large Stoke shift.
Doped nanocrystals are perfect example of this
category. As introduced dopant sates shifts the
emission band to longer wavelength, the Stoke
shift became larger and hence the chance of self-
absorption reduces. For the case of Mn doped znS,
Mn doped znSe, almost no reabsorption has been
In this communication, we report the
photophysical processes involved in various
doped nanocrystals to understand the possible
electronic transition and explained the nature
and properties of these emissions, change of
excited state lifetime and possible interference
with surface states, and also all these properties
are compared with undoped nanocrystals. Some
of the observations we have obtained agree with
the old reports and some are found new to provide
more information to understand the fundamental
aspects of electronic transition of these newly
developed doped nanocrystals.
results and Discussion
Self-Absorption:
Self-absorption or reabsorption of the
nanocrystal emitters is very common. For those
Figure 2. Schematic presentation of possible excitonic recombination paths of (a) undoped quantum dot, (b) Mn doped and (c) Cu doped nanocrystals. Two intermediate states in (b) are 4T1(4G) - 6A
1(6S) of Mn. The
intermediate state of Cu in (c) is t2 states of Cu.
2� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
observed and for Cu doped nanocrystals (znS,
or znSe), minimized reabsorption is there which
contributes negligible amount for the overall
emission quenching.�2 Figure 3 shows the emission
of nanocrystals with changing the secondary
Figure 3. (a) A schematic presentation of the measurement in Fluoremeter sample chamber. The secondary pathlength is towards the detector. Changing this path length photoluminescence (PL) has been measured. Emission changes for undoped nanocrystals is in (a) and doped nanocrystals is presented in (b).
pathlength of the sample for undoped and doped
semiconductor nanocrystals. It indicates that the
emission intensity decreases with increase of
secondary pathlength and unaltered for doped
nanocrystals.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 29
Proceedings of the National Seminar : 23 Nov 20�0
Excited State Lifetime and the Photo-Physical
Process:
As nanocrystals show emission, it is
associated with some excited state lifetime. This is
the time of the exciton takes for the recombination.
For undoped nanocrystals, which show size
tunable emission the excited state lifetime is
in nano seconds.23 This emission is the exciton
emission which positioned at the band edge
absorption of the nanocrystals. But for doped
nanocrystals, it varies and certainly the lifetime
falls in higher order than in nanosecond.�� For the
case of Mn doped nanocrystals, it is found that the
excited state lifetime remains in millisecond which
is much higher than the excitonic emission.�0 In
fact the recombination within the Mn states is d-
d forbidden and that enhances the lifetime of this
yellow emission.�0 This is a perfect tool to distinguish
the Mn dopant emission from band edge excitonic
emission. Next, for Cu doped nanocrystals whose
emission tunes with their size, the excited state
lifetime falls mostly in microseconds or hundreds
of nanoseconds which is also in much higher order
than the band edge emission.�7 Unlike Mn dopant
emission, the lifetime of Cu dopant emission tunes
with the emission tuning. Once the emission red
shifts, the lifetime of Cu dopant emission increases.
Similar trend has been observed for the excitonic
emission of the band edge emission but they are
difference in their excited state lifetime.2� Typical
lifetime plots for Mn and Cu doped nanocrystals
are shown in Figure �.
Figure 4. Lifetime decay plot for Mn doped ZnS (b) and Cu doped ZnCdS alloy.
Functionalization and Solubility:
Semiconductor nanocrystals, either
doped or undoped, they are synthesized mostly
at high reaction temperature in solution and
hence they are hydrophobic in nature. To use
them in Biology or different other potential
applications they need to be water soluble
or surface modification. Keeping the quality
of nanocrystals same, surface organics are
exchanged with appropriate new organic/s as
per the requirement.25 One of the successful
attempts to make water them soluble is using
mercaptopropionic acid or (or mercaptocarboxylic
acids) where one end has thiol which binds to the
30 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
inorganic nanocrystal surfaces26, 27 and other end has
carboxylic acid which makes them water soluble.
To use these materials in LED, they are embedded
with sometimes appropriate polymer to make a
good film. The problem of this surface modification
which is called surface functionalization is not easy.
This has high chance of creating additional energy
states mostly due to surface oxidation. These
states hinder the exciton relaxation process and
sometimes they behave like non-radiative channel
or create another emission at longer wavelength.
One of the advantages of doped nanocrystals is
that the excitonic process is not harmed with these
surface states. Even the surface gets oxidized, the
exciton follows the more allowed dpant states and
hence the emission is not quenched like undoped
nanocrystals. This helps to make them a potential
candidate for various applications.
Thermal Stability and Photo-Stability:
Undoped quantum dots has phonon
coupling and hence with increase of temperature
the emission intensity decreases. This is a
disadvantage for these nanocrystals for their
application is light emitting devices as heat can
generate for long time use which can reduce the
emission intensity. It is found that within �50 oC,
the emission of CdSe nanocrystals completely
quench.22 However, this process is reversible
and during cooling the emission reappears. But
fortunately doped nanocrystals are sable at least
till 300 oC which we have measured for Mn doped
as well as Cu doped znSe (or znS) nanocrystals.
The lattice vibration with increase of temperature
does not harm the exciton recombination process
of these nanocrystals. Figure 5 shows the digital
image of Mn doped znSe showing bright emission
at different temperatures.
Photo-oxidation is another harmful
process to quench the emission of nanocrystals. In
presence of UV light and oxygen the nanocrystal
surface gets photo-oxidized very quickly and
hence undoped quantum dots are always kept
under Argon for their applications. As stated
above even oxidations states are created in doped
nanocrystals but their excitonic recombination
is not harmed and hence these would be useful
for many applications as the emission is not
susceptible to photo-oxidation.
Current Applications and Future Prospects:
As stated above doped nanocrystal
emitters whose intensity is as similar to undoped
nanocrystals can be useful for various applications
e.g. making light emitting devices, biological
labeling etc. These are free from heavy metal
cadmium and hence would be acceptable by
the community. Unfortunately these doped
nanocrystals do not have all color emission
and their higher excited state lifetime always
provide less emission in comparison to undoped
quantum dots. However, the field of this research
is just started and hope in near future the details
of synthesis, mechanism of origin of doped
nanocrystals, their various applicatiosn etc would
come out and would be helpful in various practical
applications.
Figure 5. Digital images of the reaction flask of Mn doped ZnSe at different reaction temperature. Excitation wavelength is 365 nm.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 3�
Proceedings of the National Seminar : 23 Nov 20�0
Experimental
Mn or Cu doped semiconductor (ZnS,
ZnSe, ZnCdS, ZnCdSe) nanocrystals are synthesized
following a generic synthetic method using dopant
oxides as dopant source.
materials. zinc stearate (zn(St)2, tech), zinc
undecylenate (zn(Un)2, 9�%), Octadecylamine
(ODA, 97%), �-Octadecene (ODE, tech.), Oleylamine
(OA, tech.,70%), Manganese acetate tetrahydrate
(Mn(OAc)2;�H
2O), 99%), Stearic acid (SA), Quinine
sulphate dehydrate dye and Sulfur (S) powder
were purchased from Aldrich. Selenium powder
(200 mesh, 99.99%) was purchased from Alfa-
Aesar. Cupric acetate monohydrate (Cu(OAc)2;H
2O),
has been purchased from Loba Chemie.
Tributylphoshphine (TBP, 97%) was purchased
from Spectrochem. Cadmium oxide (brown) was
purchased from Fluka. All these chemicals were
used without further purification.
metal oxide nanocrystals synthesis. Metal
oxide nanocrystals are synthesized by thermal
decomposition of respective metal carboxylates
in presence of fatty amines in a modified literature
method (Jana et. al. Chem. Mater. 200�, �6, 393�).
In a typical synthesis, 0.5 mmol of manganese
acetate and 5 ml oleylamine are loaded in a 25 ml
three necked flask, degassed by purging Argon
and heated to �50 oC. After annealing 30 min at
this temperature, the reaction was cooled to room
temperature and manganese oxide nanocrystals
are precipitated using methanol as non-solvent.
These oxide nanocrystals are purified by
washing with methanol and stored in chloroform
for reaction. XRD supports these manganese
oxides are Mn3O
� and their size varies (up to 20
nm) depending on the annealing time. Cu oxides
are prepared similarly from their carboxylate
(acetate) precursors decomposition.
synthesis of Doped Zns nanocrystals. For Mn
doped zinc sulfide nanocrystals first the host
znS nanocrystals were synthesized and Mn3O
�
solutions were injected during growth stage.
For znS nanocrystals synthesis, 0.� mmol of zinc
Stearate, zn(St)2 and �0 ml of ODE are loaded in a
50 ml three necked flask, degassed for �0 minutes
at �00 oC by purging with argon and then heated
to 300 oC. In a vial, 0.5 mmol S powder in � ml of
ODE was taken with 0.3 g of ODA under argon and
mixture was injected into the above reaction flask
at 300 oC. The temperature was reduced to 250oC
and � ml of Mn3O
� stock solution was injected. Then
the reaction temperature was again increased to
2�0 oC for znS growth. �.0 mmol zn(St)2 with 0.5
mmol SA in 5 ml of ODE were injected into it. The
mixture was annealed at 250 oC for �0 min and
cooled to room temperature. In case of copper
doped znS, after the sulfur injection the reaction
flask was cooled to ��0 oC and � ml of CuO
solution oleylamine was added drop wise into it.
The mixture was annealed at that temperature for
60 min.
Synthesis of other doped nanocrystals
are followed in similar method. Host nanocrystals
are synthesized following literature methods.
instrumentation:
UV-Vis and Photoluminescence
spectra were collected using Shimadzu UV 2550
spectrophotometer and Horiba Jobin Yvon
Fluromax-� spectroflurometer respectively.
TEM images were taken on a JEOL-JEM 20�0
electron microscopy using 200 kV electron source.
Specimens were prepared by dropping a drop
32 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
of purified nanocrystal in chloroform or water
on a carbon coated copper grid, and the grids
were dried in air. ICP was done by Perkin – Elmer
Optima 2�00 DV machine. Samples for ICP were
prepared using a method described elsewhere.
XRD of the doped sample was performed by
Bruker D� Advance powder diffractometer, using
Cu Kα (λ= �.5� Ǻ) as the incident radiation. EPR
measurement was done using a 9.5 GHz Bruker
ESP-300 spectrometer operated at X-band
frequency.
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P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 33
Proceedings of the National Seminar : 23 Nov 20�0
BIAS ESTIMATION STRATEGIES
M.V.Bhaskarachary�, J.R.Pati2 and M.C.Adhikary3
�Integrated Test Range, Defence R&D Organization, Chandipur756025
Email: [email protected], Tel. No: 09�37297�2� 2 Balasore College of Engineering & Technology, Balasore 756060
Email: jnyana.pati9�@gmail.com, Tel. No: 09�37��5299 3 P.G. Department of Applied Physics and Ballistics, FM University, Balasore 7560�9
Email: [email protected], Tel. No: 09�3��200�7
Abstract
Bias estimation is a prerequisite to data fusion and processing before deploying
the Tracking instruments in a Missile Test Range for obtaining accurate measurements.
Various bias estimation strategies using Kalman Filtering techniques are explored in
this paper. The strategies mentioned can be adopted any type of problem with suitable
models.
1. introduction
In a Test Range various tracking instruments
deployed to track the airborne weapon in real
time have got different accuracies. Some of
these instruments like radars have fixed offsets
called biases with reference to true values or more
accurate sources. Bias is a constant offset in a
measurement by an instrument with reference to
a true value. Here the true value is generally track
Keywords: Bias, Filtering, Range, Azimuth, Elevation, Synchronization, Real time, Tracking, Simulation,
Modeling.
data obtained by an accurate measurement
source like Differential GPS system. Tracking
radar measures the position of an object in
space and gives Range, Azimuth, and Elevation
of the object including other parameters. These
measurements may be biased and the biases
are to be estimated prior to a real flight as a
part of calibration in dynamic conditions from
Contributed Paper
3� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
the data obtained during helicopter sorties.
These biases are assumed to be constant in
Azimuth, and Elevation. And the Range bias
may vary as a function of Range.
A bias is defined as systematic constant
or slowly variant error in all measurements. These
biases are mainly due to an incorrect sensor
calibration and signal propagation.
Bias = Measured value – True value
1.2 Kalman Filter
In statistics, the Kalman Filter [�] is a
mathematical method named after Rudolf E.
Kalman. Its purpose is to use measurements
that are observed over time that contain noise
(random variations) and other inaccuracies, and
produce values that tend to be closer to the true
values of the measurements and their associated
calculated values. The Kalman filter has many
applications in technology, and is an essential
part of the development of space and military
technology. Perhaps the most commonly
used type of very simple Kalman filter is the
phaselocked loop, which is now ubiquitous in
FM radios and most electronic communications
equipment. Extensions and generalizations to
the method have also been developed.
The Kalman filter produces estimates
of the true values of measurements and their
associated calculated values by predicting a
value, estimating the uncertainty of the predicted
value, and computing a weighted average of
the predicted value and the measured value.
The most weight is given to the value with the
least uncertainty. The estimates produced by the
method tend to be closer to the true values
than the original measurements because the
weighted average has a better estimated
uncertainty than either of the values that went
into the weighted average.
From a theoretical standpoint, the Kalman
filter is an algorithm for efficiently doing exact
inference in a linear dynamical system, which is a
Bayesian model similar to a hidden Markov model
but where the state space of the latent variables
is continuous and where all latent and observed
variables have a Gaussian distribution (often a
multivariate Gaussian distribution).
The Kalman filter is a recursive estimator.
This means that only the estimated state from the
previous time step and the current measurement
are needed to compute the estimate for the
current state. In contrast to batch estimation
techniques, no history of observations and/or
estimates is required. In what follows, the notation
xn|m
represents the estimate of x at time n given
observations up to, and including at time m .
The state of the filter is represented by two variables:
xk|k
, the a posteriori state estimate at time k given
observations up to and including at time k;
Pk|k
, the a posteriori error covariance matrix (a
measure of the estimated accuracy of the state
estimate).
The Kalman filter can be written as
a single equation, however it is most often
conceptualized as two distinct phases: Predict
and Update. The predict phase uses the state
estimate from the previous timestep to produce
an estimate of the state at the current timestep.
This predicted state estimate is also known as
the a priori state estimate because, although it
is an estimate of the state at the current timestep,
it does not include observation information
from the current timestep. In the update phase,
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 35
Proceedings of the National Seminar : 23 Nov 20�0
the current a priori prediction is combined with
current observation information to refine the
state estimate. This improved estimate is termed
the a posteriori state estimate.
Typically, the two phases alternate,
with the prediction advancing the state until
the next scheduled observation, and the update
incorporating the observation. However, this is
not necessary; if an observation is unavailable
for some reason, the update may be skipped and
multiple prediction steps performed. Likewise, if
multiple independent observations are available
at the same time, multiple update steps may be
performed (typically with different observation
matrices Hk).
Predict
Predicted (a priori) state estimate
xk|k -�
= FkX
k-�|k-� + B
ku
k
Predicted (a priori) estimate covariance
Pk|k -�
= FkX
k-�|k-� F
kT+ Q
k
Update
Innovation or measurement residual
yk
= zk
- Hk
xk|k-�
Innovation (or residual) covariance
Sk
= Hk
Pk|k-�
Hk
T +Rk
Optimal Kalman gain
Kk
= Pk|k-�
Hk
T Sk
-�
Updated (a posteriori) state estimate
Xk|k
= Xk|k-�
+ Kky
k
Updated (a posteriori) estimate covariance
Pk|k
= (I - KkH
k) + P
k|k-�
The formula for the updated estimate and
covariance above is only valid for theoptimal
Kalman gain.
invariants
If the model is accurate, and the values for x0|0
and P0|0 accurately reflect the distribution of the
initial state values, then the following invariants
are preserved: (all estimates have mean error
zero)
E [xk - x
k|k]
= E [x
k - x
k|k -�] = 0
E [yk ] = 0
Where E [ ε ] is the expected value of ε, and
covariance matrices accurately reflect the
covariance of estimates.
Pk|k
= cov (xk- x
k|k)
Pk|k-�
= cov (xk- x
k|k-�)
Sk|k
= cov (yk)
1.3 example
Consider a truck on perfectly frictionless,
infinitely long straight rails. Initially the truck is
stationary at position 0, but it is buffeted this way
and that by random acceleration. We measure
the position of the truck every t seconds, but
these measurements are imprecise; we want to
maintain a model of where the truck is and
what its velocity is. We show here how we derive
the model from which we create our Kalman
filter.
Since f, h, r and Q are constant, their
time indices are dropped. The position and velocity
of the truck is described by the linear state space
x
k =[ x ] x
Where x is the velocity, that is, the
derivative of position with respect to time.
We assume that between the (k − �)st
and kth timestep the truck undergoes a constant
acceleration of ak that is normally distributed, with
mean zero and standard deviation σa.
36 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
From Newton’s laws of motion we
conclude that
xk
= Fxk-�
+ Gak
Note that there is no Bu term since there
is no known control inputs,
where F = [ � ∆t ] and G =[ ∆t2
], so that
0 � ∆t
xk = Fx
k-1 + w
k
Where wk~ N(0, Q) and Q =GGT σ2 =[ ]
a
At each time step, a noisy measurement
of the true position of the truck is made. Let
us suppose the measurement noise vk is also
normally distributed, with mean 0 and standard
deviation σz.
zk = Hx
k + v
k
Where H = [1 0] and R = E [vk vT] = [σ2]
k z
We know the initial starting state of the truck with
perfect precision, so we initialize
x0|0
=[ 0 ] 0
and to tell the filter that we know the exact
position, we give it a zero covariance matrix:
P0|0
= [ 0 0 ] 0 0
If the initial position and velocity are
not known perfectly the covariance matrix
should be initialized with a suitably large number,
say L, on its diagonal.
P0|0
= [ L 0 ] 0 L
The filter will then prefer the information
from the first measurements over the information
already in the model.
2. Bias estimation strategies
Kalman Filtering is a technique for
filtering and prediction which had been used
extensively in many applications. The idea is to
utilize this technique for estimation of biases and
establish a profound mechanism to quantify
and correct the bias errors. The following three
strategies are explored.
2.1 strategy 1
Data obtained from an accurate
source from Differential GPS (DGPS) is
taken as a reference to estimate the biases
based on the differences with reference to
a common reference frame after making the
required transformations. The computations
are made in Cartesian reference frame. The
data obtained from DGPS primarily consisting
of Time, Latitude, Longitude and Altitude
of a flight vehicle which is converted in
to a Cartesian reference frame T�,X
�,Y
�,z
� (
Reference taken as point “O” say). Radar data
obtained consisting of Time, Range , Azimuth
and elevation which is converted to Cartesian
reference frame T2,X
2,Y
2,z
2 (Reference taken as
point “R” say). After proper time synchronization,
appropriate Kalman Filtering is used in both
the sets of data to remove the noise and
to compensate any modeling errors. After
filtering the data is transformed back to a
common reference point and R, A, E biases are
estimated. This estimation can be done in off line
after obtaining the track data from simulations
or from a real flight data. These bias corrections
can be applied in real flight situations after
proper validations.
∆t4 ∆t3
4 2 σ2
a∆t3
2 ∆t2
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 37
Proceedings of the National Seminar : 23 Nov 20�0
2.2 strategy 2
Another strategy is to augmentation
of state[2]. The bias vector is appended to
the state vector, and he bias dynamic equation
= 0 is appended to the original process dynamic
equation to form an augmented dynamic system.
A Kaman filter applied to the new system then
estimates the state of the original problem as
well as the bias terms. However, when the number
of bias terms is comparable to or larger than
the number of states of the original problem,
the implementation of the filter involves much
larger matrices, which may pose the numerical
conditioning difficulties and effect the accuracy
of bias estimation.
2.3 strategy 3
Another strategy is to estimate the biases
of a set of Radars R�, R
2…R
N by formulating
appropriate error models [3]. All these radar bias
estimation methods are based on processing
differences of measurements taken from pairs
of sensors and referred to the same aircraft. It is
important to notice that the first measure used
in the measurement pair needs to be extrapolated
(using the velocity estimation of the track to
which the two plots are associated with) to the
second measure timestamp. The three methods
are a) Bias estimation based on LSE estimator, b)
Bias estimation based on MSE estimator and c)
Bias estimation based on Extended Kalman Filter.
3. summary
Various strategies for estimating the biases are
mentioned in this paper. The first strategy is simple
to implement and the biases can be estimated in
offline by calibration trials before the actual flight.
Reducing the computational effort in real time,
the same can be implemented in real flight also
with appropriate logics. The second strategy
of State Augmentation [2] is more logical at
cost of computational complexities which can
be minimized by separate bias estimation with
reduced order kalman filter. The third strategy
requires more number of tracking sources
connected in a network with appropriate error
models [3]. The estimates obtained in all the
three strategies can be compared with simulated
data and methods can be adapted to various
applications.
references
[�] Kalman Filter Wikipedia [2] D Haessig, B Friedlan “SeparateBias Estimation with
ReducedOrder Kalman Filters” IEEE Transactions on Automatic Control, Vol �3 No.7, July �99�
[3] A.S.Jaramillo, J.A.B. Portas, J.R.Casar Corredera, J.I.Portillo Garcia “Online Bias Estimation of Secondary Radar Network for ATC” Universidad Politécnica de Madrid Despacho C3�5.�. ETSI de Telecomunicación Ciudad universitaria, Sno.2�0�0 Madrid, Spain.
3� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
AN INTRODUCTION TO SOME IMPORTANT FORCES ACTING ON A SPINNING PROJECTILE
PK Mahapatra
Scientist-F ( Retd),PXE, Chandipur
Abstract
When in flight, the main forces acting on a projectile are gravity, drag, and if present,
wind. Gravity imparts a downward acceleration on the projectile, causing it to drop
from the line of sight. Drag or the air resistance decelerates the projectile. Wind makes
the projectile deviate from its trajectory. During flight gravity, drag and the wind have
major impact on the path of the projectile, and must be accounted for when predicting
how the projectile will travel.
Drag opposes the motion but is not exactly opposite to the longitudinal axis of the
projectile. This give rise to yaw and introduces instability. Imparting spin is a method
to stabilise a projectile. But this introduces other impediments. Some of such important
impediments have been discussed in this short introductory presentation.
introduction
Generally, a body moving through the atmosphere
is affected by a variety of forces. Some of those
forces are mass forces, which apply at the center
of gravity of the body and depend on the body
mass and the mass distribution. A second group
of forces is called aerodynamic forces, resulting
from the interaction of the projectile with the
surrounding airflow.
A quite simple experimental photographic
technique which enables the visualization of
the flow of air in the vicinity of a moving body
produces a picture called a “shadowgraph”.
The first photograph shows a projectile traveling at
approximately approx. 850 m/s
Contributed Paper
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 39
Proceedings of the National Seminar : 23 Nov 20�0
At least three different shock waves can
be distinguished. The first and most intensive one
emerges from the projectile’s nose and is called
the Mach cone. A second shock wave originates
from the location of the cannelure, and the third
shock wave forms behind the projectile’s base.
Besides, a highly turbulent flow behind the base
can be seen. It is called the wake.
The flow type at the projectile’s surface
changes from a laminar boundary layer at
the forward region of the projectile, which is
characterized by parallel stream lines, into a
turbulent flow showing vortexes, beginning at the
cannelure.
For a projectile, moving slightly faster
than the speed of sound, one finds the following
significant differences: the Mach cone is still
present but no longer attached to the projectile’s
tip and the vertical angle of this cone has increased.
The wake is still visible,
forces and moments
The shadowgraphs have shown that the flowfield
in the vicinity of a projectile most generally
consists of laminar and turbulent regions. The
flowfield depends mostly on :
➢ the projectile’ velocity
➢ its shape, and
➢ the surface roughness.
The flowfield obviously changes
tremendously, as the velocity drops below the
speed of sound, which is about 3�0 m/s at standard
atmospheric conditions.
The mathematical equations, by means
of which the flowfield parameters (for example
pressure and flowfield velocity at each location)
might be determined are well known as the
Navier-Stokes equations. With the help of powerful
computers, numeric and practically useful
solutions to these equations have been found up
to now only for very specific configurations.
Because of these computational
restrictions, ballisticians all over the world
consider projectile motion in the atmosphere
by disregarding the specific characteristics of
but the boundary layer appears to be laminar
from the tip to the base, all along the projectile’
s surface.
Finally, for another projectile, moving at
subsonic speed, all shock waves are absent, and
what remains is slight turbulences behind the
projectile’s base.
�0 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
Let F� be the resultant wind force (air
resistance) opposing the motion of a projectile
moving with velocity v and a yaw angle δ This
force seems to apply at the centre of pressure
CP of the wind force. The location of the center
of pressure depends on the flow field structure,
in other words, depending on whether the bullet
is in supersonic, transonic or subsonic flight. It
also depends on the projectile conditions and
the surface exposed to the force during the spin.
Since for all practical purposes the flight of the
projectile is considered by tracing the path of its
CG, we shall shift the force acting at CP to CG and
proceed further.
overturning moment
Introduce two equal and opposite forces fW
and
f2, (both equal to F
�) at the CG. These mutually
neutralize.
Now let us consider the two forces f� and
f2. It can be shown that this couple is a free vector,
which is called the aerodynamic moment of the
wind force or, for short, the overturning moment
mW
, or, the yawing moment.
We can proceed one step further and
split the force fW
, which applies at the CG, into
a force which is parallel but opposite to the
direction of movement of the CG plus a force,
which is perpendicular to this direction. The first
force is said to be the drag force fD or simply drag,
the other force is the cross-wind force. Thus
cross wind force is the component of the total
air resistance perpendicular to the trajectory, in
the plane of yaw. It introduces lateral shift for the
projectile.
The overturning moment mW
tends to
rotate the projectile about an axis, which goes
through the CG and which is perpendicular to the
plane of drag, the plane, formed by the velocity
vector v and the longitudinal axis of the projectile.
Obviously, the overturning moment tends to
tumble the projectile end over end.
If the CP is kept behind the CG by
introduction of fins, as in case of mortars, APFSDS
shots and missiles, overturning moment is
overcome. If, on the other hand, the CP is ahead
of the CG, as in case of artillery projectiles,
introduction of spin is the only way out.
Gyroscopic effect comes into play. This opposes
the overturning moment and tends to keep the
axis in the original direction.
side effects of gyroscopic effect
According to the laws of gyroscope, the action
of the projectile in seeking to overcome this
overturning moment must manifest itself in a
the flowfield and apply a simplified viewpoint:
the flowfield is characterized by the forces and
moments affecting the body.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | ��
Proceedings of the National Seminar : 23 Nov 20�0
precession of the projectile about the direction
of the force which creates the moment. Also,
the projectile having right handed spin, the
precessional revolution must be clock-wise as
viewed from the rear.
Generally, the wind force is the dominant
aerodynamic force. However, there are numerous
other smaller forces but we will consider the
magnus force and cushioning force, which turn
out to be very important for projectile stability
and also drift.
magnus force
A spinning object creates a kind of whirlpool of
rotating air about itself. On one side of the object,
the motion of the whirlpool will be in the same
direction as the wind stream that the object
is exposed to. On this side the velocity will be
increased. On the other side, the motion of the
whirlpool is in the opposite direction of the wind
stream and the velocity will be decreased. The
pressure in the air is reduced from atmospheric
pressure by an amount proportional to the square
of the velocity, so the pressure will be lower on
one side than the other causing an unbalanced
force at right angles to the wind.
With respect to the figure, we are looking
at a projectile from the rear spinning clockwise.
We additionally assume the presence of an angle
of yaw δ. The projectile’s longitudinal axis should
be inclined to the left. Thus, there is a pressure
difference, which results in a downward (only in
this diagram!) directed force, which is called the
magnus force fm
.
The Magnus effect has a significant role
in bullet stability because the Magnus force does
not act upon the bullet’s center of gravity, but
the center of pressure, affecting the yaw of the
bullet. If the centre of pressure is ahead of the
CG then Magnus force has a destabilising effect.
The following variables affect the magnitude of
gyroscopic drift:
• Projectile length: longer projectiles
experience more gyroscopic drift because
they produce more lateral “lift” for a given
yaw angle.
• Spin rate: faster spin rates will produce more
gyroscopic drift because the nose ends up
pointing farther to the side.
• Range, time of flight and trajectory height:
gyroscopic drift increases with all of these
variables.
cushioning force
The theory of cushioning force also depends on
the obliquity of the projectile. If the underside
is presented to the air stream, the air banks up
against this side, forming a sort of hard cushion.
The projectile tends to roll on this cushion because
of the friction imposed by it. This movement is to
�2 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
the right in a projectile with right-handed spin. As
the projectile moves down the range it builds up
speed while moving to the right and the further
downrange it goes the faster it moves to the right
as it accumulates right-hand speed due to the
rolling motion on the cushion of air. This is also
known as Poisson’s effect.
spin damping moment
Skin friction at the projectile’s surface retards its
spinning motion. However, the angular velocity
of the rotating projectile is much less damped by
the spin damping moment than the translational
velocity, which is reduced due to the action of the
drag force.This is the reason why projectiles, which
are gyroscopically stable at the muzzle will remain
gyroscopically stable for the rest of their flight.
coriolis effect
Before concluding, we shall discuss one more effect
which affects long range projectiles. These effects
cause drift related to the spin of the Earth, known
as Coriolis drift. Coriolis drift can be up, down, left or
right. It is not an aerodynamic effect. It is a result of
flying from one point to another across the surface
of a rotating planet (Earth). The direction of Coriolis
drift depends on the firer’s and target’s location or
latitude on the planet Earth, and the azimuth of
firing. The magnitude of the drift depends on the
firing and target location, azimuth, and time of
flight. The Coriolis effect is at its maximum at the
poles and negligible at the equator of the Earth.
conclusion
Once a projectile is out of the gun it forces its way
through the atmosphere and thus is affected by
it. Some are inherent, like that of gravity. Some are
created because of its motion, like air resistance.
If the projectile’s axis coincides with the tangent
to the trajectory at the CG throughout the
trajectory from gun muzzle to the target, then
life would have been much simpler! There would
not be any requirement of fin or gyroscopic
stabilisation, there will not be any crosswind force,
no precession and no Magnus force. Of course
there will be Coriolis effect. No pure analytical
model has been developed till now to exactly
predict all the forces and their effects by taking
the projectile parameters and initial conditions
as input and pinpoint the arrival point before the
projectile arrives there.
references:
[�] How do bullets fly? by Ruprecht Nennstiel, Wiesbaden, Germany (www.nennstiel-ruprecht.de/ )
[2] Gene Slovers US Navy Pages – Exterior Ballistics �935, Chapter 9 (www.eugeneleeslover.com)
[3] en.wikipedia.org
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �3
Proceedings of the National Seminar : 23 Nov 20�0
THE IMPORTANCE OF PLASTIC DEFORMATION AND CYCLIC STRESS IN WEAPON DESIGN
G. C. Rout
Condensed Matter Physics Group, Dept. of Applied Physics and Ballistics,
F. M. University, Vyasa Vihar, Balasore - 7560�9.
Abstract
The weapons are made of special materials having the characteristics of high ductility,
high fatigue resistance and very high yield-stress with high strain hardening qualities.
This communication briefly reports the plastic deformation with respect to tensile and
shear stress of the materials. Further it discuses how cyclic stress induces fatigue in
the materials and emphasizes the importance of the endurance limit of the materials.
Finally it emphasizes the importance of the plastic deformation and fatigue in the
weapon design.
Key words: Plastic deformation, yield-strength, fatigue, endurance limit.
1. introduction
The weapon designer requires the basic
forces acting on the projectiles and guns and the
mechanics of the materials [�]. Before weapon
design one should know several special materials
that can support higher stresses. Here we present
stress-strain relations in section 2 and the plastic
deformation in section 3. The section � deals
with the failure criteria. We discuss the fatigue of
materials in section 5 and the endurance limit in
section 6 and finally the conclusion in section 7.
2. stress- strain relations
Before proceeding to examine the
weapon design practice, one should discuss
the fundamentals of the general state of stress
in materials. The stress defines the force acting
on unit surface area. The stress on the material
gives rise to the strain. Here the strain in the
material is defined as the change length of a part
over its initial length. We require a relationship
between stress and strain to evaluate the material
behaviour under a load. According to the Hooke’s
Contributed Paper
�� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
a metal or plastic? Whether it has a distinct yield-
strength? Is it very brittle or ductile? Accordingly
we have three criteria for the yield or failure of
weapon components. These criteria are the Von
Mises, Tresca and Coulomb [3]. The Von Mises
criterion is applicable for metals and it assumes the
maximum distortion energy required to change
the shape of the material causing the yielding. The
material has a distinct yield-strength. If σ�, σ
2, σ
3 be
the principal tensile stresses, the conditions are
(σ� - σ
2) 2 + (σ
2 - σ
3) 2 + (σ
3 - σ
�) 2 = 6τ 2
and τ = �.�55 (σy / 2) (�)
Where, σy and τ are the yield-strength in simple
tension and in pure shear respectively. τ and σy
can be found experimentally. The Tresca or the
maximum shear stress condition is used for the
material with great ductility. The condition for a
weapon component not to exhibit failure is
(σ� - σ
3) < σ
y and τ = σ
y / 2 (2)
The Mohr-Coulomb or maximum normal stress
criterion is applied to the brittle materials which
show no yielding point. The condition for no
failure in the material is
σ�, σ
2, σ
3 < σ
U (3)
i. e. all the principal stresses must be less than the
ultimate stress σU of the material.
The designer takes into account these
criteria, while designing the weapons. The
weapons are categorized by their uses as gun
(low angle, line-of-sight, direct fire), howitzers
(high angle, beyond line-of-sight, indirect fire)
or mortars (very high angle, short range, indirect
fire). There are several types of tube designs
encountered in service weapons: (i) the monobloc
tube is made from one piece of metal which is
not the most efficient, (ii) the jacketed tube which
consists of separate layers or jackets built up as a
composite structure. This type is most obsolete
now, and (iii) autofrettaging or self-jacketing in
which the quasi-two piece tube is formed by
inserting a liner into an otherwise monobloc tube.
This pressure containing tube allows for a more
resilient material for the projectile to ride against
and helps the wear of the tube.
5. cyclic stress and fatigue
Many components in civil and military
services are subject to fatigue. The fatigue is the
term used for a mechanical part that undergoes
cyclic loading and fails suddenly. A part that is
subject to fatigue failure has been subjected to
many small loads that stresses the components
below the yield strength. Damage begins to
accumulate through various mechanisms. A simple
example of fatigue is where you take a metal
paper clip and bend it 900. After this first bend,
the paper clip is still in one piece and the ultimate
yield-strength of the material is not exceeded. If
one repeats this multiple times with the same
paper clip, it will eventually break. This failure can
occur even without yielding the material.
A projectile usually undergoes one
cycle of loading and so fatigue is normally not
an issue. Gun tubes undergo thousands of cycles
and fatigue is a major consideration in their
design. The weapon design practice is to ensure
that a weapon shots out, before it fatigues out.
law, the strain is proportional to stress. In ordinary
materials, the tensile stress will reach some
critical value of stress (σ0), called the tensile yield-
strength. When this stress is removed, a very small
permanent strain (usually 0.0� % to 0.02 %) still
remains. The stress-strain relation is linear below
the yield-strength. When the strain increases
too much beyond the yield point, the material
deforms permanently up to a maximum stress
(σmax
). This permanent deformation is called the
plastic deformation. The process whereby the
plastic deformation increases the yield-strength
is called the strain hardening [�]. The plastically
deformed materials with high strength of the strain
hardening are the important criteria for selecting
the material as gun material. A specialized steel is
more suitable as weapon material.
3. Plastic deformation of materials
If a pure copper rod is twisted, it at first
behaves elastically i.e. the shear strain increases
linearly up to the shear yield-strength (τ0 ∼ 6000
psi) of copper. If the copper rod is twisted too
much, it deforms permanently. This permanent
deformation is called the plastic deformation of
copper metal. It should be noted that the volume
remains constant during the plastic deformation.
Sometimes the original rod is capable of a large
plastic deformation. This shows the ductile nature
of the material. The maximum shear strain (γmax
)
is a measure of the ductility of the material. The
ductility of copper is 2 and the corresponding
shear yield-strength rises from τ0 = 6000 psi in
the elastic region to τmax
= 30,000 psi in the plastic
deformation region. The process whereby the
plastic deformation increases the yield-strength is
called the strain hardening. The copper rod begins
to show fracture at the shear yield-strength of τmax
.
We note here that it is necessary as
exactly as possible to know the nature of copper.
The copper with a slightly different composition,
a different history or copper which has been
mechanically deformed will behave differently.
The pure copper is conveniently used as projectile
material for a shear stress of 25,000 psi at a shear
strain of 0.9. In contrast to copper, the window glass
or a piece of chalk exhibits only elastic behaviour,
but not the plastic behaviour. They are known as
brittle materials that can not be considered as the
weapon grade materials.
The tensile test on the copper shows that
the tensile stress increases linearly with strain in
the elastic region up to a tensile yield-strength (σ0
= �0,000 psi) corresponding to the tensile strain
of 0.0�. On further increasing the strain, the plastic
deformation begins in copper up to the fracture
print with plastic yield-point of σmax
= 35,000
psi at a strain of ε = 0.5. Beyond this strain the
specimen exhibits necking showing the plastic
instability. Hence it is convenient to work with
pure copper as a weapon grade material with a
yield-strength of 30,000 psi at strain ε = 0.�5. It is
more convenient to work with the real stress (σr)
and real strain (εr) in dealing with large strains. The
empirical expression σr = Kε
rn represents plastic
deformation region of the ductile materials. K and
n are constants and n is called the strain hardening
exponent. Certain materials can be stretched to
�000% without fracture. This behaviour of the
material is called the superplasticity.
4. failure criteria
Before the design of the weapon
components, we have to determine the
characteristics of the materials [�, 2]. Will we use
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �5
Proceedings of the National Seminar : 23 Nov 20�0
a metal or plastic? Whether it has a distinct yield-
strength? Is it very brittle or ductile? Accordingly
we have three criteria for the yield or failure of
weapon components. These criteria are the Von
Mises, Tresca and Coulomb [3]. The Von Mises
criterion is applicable for metals and it assumes the
maximum distortion energy required to change
the shape of the material causing the yielding. The
material has a distinct yield-strength. If σ�, σ
2, σ
3 be
the principal tensile stresses, the conditions are
(σ� - σ
2) 2 + (σ
2 - σ
3) 2 + (σ
3 - σ
�) 2 = 6τ 2
and τ = �.�55 (σy / 2) (�)
Where, σy and τ are the yield-strength in simple
tension and in pure shear respectively. τ and σy
can be found experimentally. The Tresca or the
maximum shear stress condition is used for the
material with great ductility. The condition for a
weapon component not to exhibit failure is
(σ� - σ
3) < σ
y and τ = σ
y / 2 (2)
The Mohr-Coulomb or maximum normal stress
criterion is applied to the brittle materials which
show no yielding point. The condition for no
failure in the material is
σ�, σ
2, σ
3 < σ
U (3)
i. e. all the principal stresses must be less than the
ultimate stress σU of the material.
The designer takes into account these
criteria, while designing the weapons. The
weapons are categorized by their uses as gun
(low angle, line-of-sight, direct fire), howitzers
(high angle, beyond line-of-sight, indirect fire)
or mortars (very high angle, short range, indirect
fire). There are several types of tube designs
encountered in service weapons: (i) the monobloc
tube is made from one piece of metal which is
not the most efficient, (ii) the jacketed tube which
consists of separate layers or jackets built up as a
composite structure. This type is most obsolete
now, and (iii) autofrettaging or self-jacketing in
which the quasi-two piece tube is formed by
inserting a liner into an otherwise monobloc tube.
This pressure containing tube allows for a more
resilient material for the projectile to ride against
and helps the wear of the tube.
5. cyclic stress and fatigue
Many components in civil and military
services are subject to fatigue. The fatigue is the
term used for a mechanical part that undergoes
cyclic loading and fails suddenly. A part that is
subject to fatigue failure has been subjected to
many small loads that stresses the components
below the yield strength. Damage begins to
accumulate through various mechanisms. A simple
example of fatigue is where you take a metal
paper clip and bend it 900. After this first bend,
the paper clip is still in one piece and the ultimate
yield-strength of the material is not exceeded. If
one repeats this multiple times with the same
paper clip, it will eventually break. This failure can
occur even without yielding the material.
A projectile usually undergoes one
cycle of loading and so fatigue is normally not
an issue. Gun tubes undergo thousands of cycles
and fatigue is a major consideration in their
design. The weapon design practice is to ensure
that a weapon shots out, before it fatigues out.
law, the strain is proportional to stress. In ordinary
materials, the tensile stress will reach some
critical value of stress (σ0), called the tensile yield-
strength. When this stress is removed, a very small
permanent strain (usually 0.0� % to 0.02 %) still
remains. The stress-strain relation is linear below
the yield-strength. When the strain increases
too much beyond the yield point, the material
deforms permanently up to a maximum stress
(σmax
). This permanent deformation is called the
plastic deformation. The process whereby the
plastic deformation increases the yield-strength
is called the strain hardening [�]. The plastically
deformed materials with high strength of the strain
hardening are the important criteria for selecting
the material as gun material. A specialized steel is
more suitable as weapon material.
3. Plastic deformation of materials
If a pure copper rod is twisted, it at first
behaves elastically i.e. the shear strain increases
linearly up to the shear yield-strength (τ0 ∼ 6000
psi) of copper. If the copper rod is twisted too
much, it deforms permanently. This permanent
deformation is called the plastic deformation of
copper metal. It should be noted that the volume
remains constant during the plastic deformation.
Sometimes the original rod is capable of a large
plastic deformation. This shows the ductile nature
of the material. The maximum shear strain (γmax
)
is a measure of the ductility of the material. The
ductility of copper is 2 and the corresponding
shear yield-strength rises from τ0 = 6000 psi in
the elastic region to τmax
= 30,000 psi in the plastic
deformation region. The process whereby the
plastic deformation increases the yield-strength is
called the strain hardening. The copper rod begins
to show fracture at the shear yield-strength of τmax
.
We note here that it is necessary as
exactly as possible to know the nature of copper.
The copper with a slightly different composition,
a different history or copper which has been
mechanically deformed will behave differently.
The pure copper is conveniently used as projectile
material for a shear stress of 25,000 psi at a shear
strain of 0.9. In contrast to copper, the window glass
or a piece of chalk exhibits only elastic behaviour,
but not the plastic behaviour. They are known as
brittle materials that can not be considered as the
weapon grade materials.
The tensile test on the copper shows that
the tensile stress increases linearly with strain in
the elastic region up to a tensile yield-strength (σ0
= �0,000 psi) corresponding to the tensile strain
of 0.0�. On further increasing the strain, the plastic
deformation begins in copper up to the fracture
print with plastic yield-point of σmax
= 35,000
psi at a strain of ε = 0.5. Beyond this strain the
specimen exhibits necking showing the plastic
instability. Hence it is convenient to work with
pure copper as a weapon grade material with a
yield-strength of 30,000 psi at strain ε = 0.�5. It is
more convenient to work with the real stress (σr)
and real strain (εr) in dealing with large strains. The
empirical expression σr = Kε
rn represents plastic
deformation region of the ductile materials. K and
n are constants and n is called the strain hardening
exponent. Certain materials can be stretched to
�000% without fracture. This behaviour of the
material is called the superplasticity.
4. failure criteria
Before the design of the weapon
components, we have to determine the
characteristics of the materials [�, 2]. Will we use
�6 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
In other words, the weapon becomes inaccurate
because of wearing away of the rifling or the bore
well before it fails in sudden manner because of
fatigue. The maintenance crew determines this
by periodically checking the internal condition
of the bore of the weapon. If the bore has been
worn away sufficiently, the tube is condemned.
The condemnation occurs after a certain large
number of rounds have been fired. The weapon
designer limits the number of firings keeping in
eye with the fatigue life of the weapon.
6. endurance
The endurance of a material is the
ability of the material to survive multiple cycles
of loading. This ability of the material can be
described graphically by S – N diagram. The S – N
diagram plots the allowable stress (S) in psi in
the material against the number of cycles (N)
required by the designer [�, 5]. For example, if the
designer requires �0,000 cycles for a particular
design using AISI �3�0 steel, it will be necessary
to keep the stress below approximately 3�,000
psi. Some materials show endurance limit, i. e.
after a certain large number of cycles, the stress
(S) of the material stops decreasing and reaches
a limiting value. The material can withstand an
infinite number of load cycles, if operated below
this endurance stress limit. The endurance limit
of this AISI �3�0 steel is around 2�,000 psi. The
tensile stress of different specialized steel is
given in table – I. A rough rule for stress (S) is
σ0 / � < S < σ
0 / � for �0� cycles. The aliminium
is notorious in a sense that it has no endurance
limit i. e. its stress continues to decrease.
Aluminium components always have a finite
fatigue life expectancy.
Table–I Tensile yield-strength (σ0) of special iron
Materials σ0 (in thousand psi)
Gray case iron 20
Pearlite malleable cast iron �5
AISI �020 steel 35 – �0
AISI �095 steel (hardened) �00 – ��0
AISI �3�0 annealed alloy steel 65 – 70
AISI �390 fully hardened alloy steel �30 – 22�
Marraging (300) steel 290
Piano wire 350 – 500
Note: - AISI �020 stands for American Iron and Steel
Institute with the �020 for a code specifying the
alloy components of steel and psi is abbreviation
of pound/ square inch.
There are many contributing factors to
the endurance of a weapon component. They
include the material part of the weapon, the
number of loading cycles and the stress level of
each load cycle. The other factors are the rate of
loading, rate of load reversal and the surface finish
of the components [6, 7]. The load that can not be
exceeded by one cycle is defined as,
Sn = S CR C
G C
S (�)
Here S is the stress in psi read from the
S – N diagram for the desired number of cycles,
CR is the factor for reliability required in the
design, CG is the factor for the rapidity of the
load reversal and CS is the factor for the surface
finish. These factors effectively reduce the
allowable stress in the part of the weapon (they
all should be ≤ �). For example, for a 70 mm gun
made of AISI �020 steel working at pressure
�3,000 psi, the typical parameters are CR = 0.93,
CG = 0.95, CS = 0.99.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �7
Proceedings of the National Seminar : 23 Nov 20�0
7. conclusion
The propellant charge and the projectile
combination apply the maximum stress to
the weapon. These pressures are applied over
and over again as the weapon tube is cycled
with each shot fired. Hence the designer has to
predict the fatigue failure of the design. Many
of the concepts discussed above are applicable
to the design of the gun tube. The idea of safety
margin is essential in the design of the gun tube.
The gun tube must remain serviceable for many
cycles at stress levels very much comparable to
the fired projectiles.
references
[�] Ruoff A. L., Introduction to Material Science, (Prentice Hall of India.)
[2] Carlucci D. E., and Jacobson S. S., Ballistics: Theory and Design of Guns and Ammunition, (CRC Press, New York, 200�)
[3] Elam C. F., Distortion of Metal Crystals (Oxford Press, New York, �935)
[�] Bishop T., Fatigue and the Comet Disasters, Metal Progress, 67 (�955)77
[5] Sines G. and Waisman J. L., Metal Fatigue, (Mc Graw Hill, New York. �955)
[6] Deutschman A. D., Michel W. J., and Wilson C. E., Machine Design, Theory and Practice (Mac millan Publishing Company, New York, �975)
[7] Norton R. L., Machine Design, An Integrated Approach, (Pearson – Prentice Hall, New York, 2006)
�� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
HIGH-SPEED IMAGING IN BALLISTICS TEST AND EVALUATION
T K Biswal and M C Adhikary *
320,Ballistics Centre,Proof & Experimental Establishment, Channdipur,Balasore-756 025
*Department of Applied Physics & Ballistics, F. M. University, Balasore
ABSTRACT
High-speed imaging plays a major role in a Test Range where the direct access is
possible through imaging in order to understand a dynamic process thoroughly and
both qualitative and quantitative data are obtained thereafter through necessary
image processing and analysis. During ballistic test & evaluation process lots of physical
events are visualized after post analysis to have a better understanding of the whole
process. Though there is a maturity in the development of high-speed imaging devices,
but now there is a trend to evolve new methodologies to meet various goals in different
fields of science and technology. This paper depicts some of the methodologies applied
to the field of experimental ballistics in recent past.
1.introDUction
Performance evaluation of any armament store
by dynamic firing is the ultimate acceptance
criteria before its issue to users. At the same time
dynamic firing data is crucial for design validation
and optimization during the development phase.
Laboratory testing and simulation studies, many
a times, do not represent the true performance as
in actual condition. It is also difficult to simulate
the actual condition in the laboratory due to the
magnitude of firing stress and environmental
effect. Hence, dynamic test and evaluation is of
paramount importance both from the designers
and users point of view. To mention some of the
techniques� evolved during recent years, this
paper primarily focuses three different aspects
of test and evaluation methodologies pertaining
to performance of �0mm proximity fuze within
a close vicinity of an aerial target, estimation of
rapid rate of fire of AK630 weapon and attitude of
a �0mm AP shot before its impact on armor.
2. DeVeloPment of methoDoloGies
Recent developments in conventional armaments
focus more on pin-pointed accuracy, rate of fire and
reliability of the product for absolute performance.
Appropriate technique to evaluate the product
becomes a challenge to range technologists due
to variety type of stores and its intended use. Since
no single technique or methodology can meet
the evaluation requirement, there is a need to
develop methodologies for deriving performance
parameters from case to case basis. Some of the
methodologies are presented in subsequent
paragraphs.
2.1 spatial information of 40mm Proximity fuze
functioning against low flying target & study of
miss Distance of non-functioning ones
Measurement of miss distance2 is a vital
parameter for the fuze designer to know the
performance of ammunitions/warhead in
the close vicinity of intended target. Spatial
measurement accuracy of this parameter is very
important to judge ammunitions lethality and its
defeating capabilities. In the evaluation process
of fuze ammunitions, it is mandatory to know
about miss distance of the fuze-based projectile
when it fails to function with respect to some
aerial target.
2.1.1 methodology
The missile target (MT) is erected at 5m height
with respect to seabed and downrange �000m
along the line of fire. It simulates a low flying
missile flying at �000m altitude. It is an extended
target of cylindrical shape with 0.2m radius,
5.0m length and made of aluminum alloy sheet.
Proper distance is maintained between the
target and gun by use of distometer/laser range
finder and the line of fire is chosen considering
the range safety in to account. MT is erected
in a horizontal way such that its body axis and
gun axis lie in a vertical plane. DGPS is used
to measure the altitude of target and that of
camera location so that camera can be adjusted
to match its axis to that of MT and both axes
lie in one horizontal straight line. Measurement
accuracy down to 0.0�m is achieved in this DGPS.
It helps to know the exact separation between
camera and target and also to ascertain both
are at same height. High-speed digital CMOS
camera, Speed Cam Visario, is used where a
maximum resolution of �536x�02� pixel is
achieved at �000pps. Its sensor has got square
pixel of size ��µm x��µm.Image acquisition is
performed through an external trigger, a flash-
trigger, that picks up muzzle flash of the gun
during firing and initiates image acquisition.
This trigger time is considered as reference time
t0 at which projectile leaves the muzzle. Camera
records the event in the post-trigger mode to
facilitate determining time to burst of fuze
functioning over MT which is obtained through
off-line video analysis. In a series of functioning
rounds, burst time is determined for each round
and then mean burst time is calculated. This is
probable because in a firing series, parameters
like charge mass, charge temperature, gun
elevation etc are maintained constant through
out. Minimum distance of the projectile with
respect to MT needs to be calculated during
flight for miss distance calculation. Ideally in
�0mm proximity ammunitions, shell is designed
to function within 3m radius with respect to
MT body axis. So a field-of-view (FOV) of more
than 3.0m radius around MT longitudinal axis is
chosen using suitable optics.
Contributed Paper
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �9
Proceedings of the National Seminar : 23 Nov 20�0
HIGH-SPEED IMAGING IN BALLISTICS TEST AND EVALUATION
T K Biswal and M C Adhikary *
320,Ballistics Centre,Proof & Experimental Establishment, Channdipur,Balasore-756 025
*Department of Applied Physics & Ballistics, F. M. University, Balasore
ABSTRACT
High-speed imaging plays a major role in a Test Range where the direct access is
possible through imaging in order to understand a dynamic process thoroughly and
both qualitative and quantitative data are obtained thereafter through necessary
image processing and analysis. During ballistic test & evaluation process lots of physical
events are visualized after post analysis to have a better understanding of the whole
process. Though there is a maturity in the development of high-speed imaging devices,
but now there is a trend to evolve new methodologies to meet various goals in different
fields of science and technology. This paper depicts some of the methodologies applied
to the field of experimental ballistics in recent past.
1.introDUction
Performance evaluation of any armament store
by dynamic firing is the ultimate acceptance
criteria before its issue to users. At the same time
dynamic firing data is crucial for design validation
and optimization during the development phase.
Laboratory testing and simulation studies, many
a times, do not represent the true performance as
in actual condition. It is also difficult to simulate
the actual condition in the laboratory due to the
magnitude of firing stress and environmental
effect. Hence, dynamic test and evaluation is of
paramount importance both from the designers
and users point of view. To mention some of the
techniques� evolved during recent years, this
paper primarily focuses three different aspects
of test and evaluation methodologies pertaining
to performance of �0mm proximity fuze within
a close vicinity of an aerial target, estimation of
rapid rate of fire of AK630 weapon and attitude of
a �0mm AP shot before its impact on armor.
2. DeVeloPment of methoDoloGies
Recent developments in conventional armaments
focus more on pin-pointed accuracy, rate of fire and
reliability of the product for absolute performance.
Appropriate technique to evaluate the product
becomes a challenge to range technologists due
to variety type of stores and its intended use. Since
no single technique or methodology can meet
the evaluation requirement, there is a need to
develop methodologies for deriving performance
parameters from case to case basis. Some of the
methodologies are presented in subsequent
paragraphs.
2.1 spatial information of 40mm Proximity fuze
functioning against low flying target & study of
miss Distance of non-functioning ones
Measurement of miss distance2 is a vital
parameter for the fuze designer to know the
performance of ammunitions/warhead in
the close vicinity of intended target. Spatial
measurement accuracy of this parameter is very
important to judge ammunitions lethality and its
defeating capabilities. In the evaluation process
of fuze ammunitions, it is mandatory to know
about miss distance of the fuze-based projectile
when it fails to function with respect to some
aerial target.
2.1.1 methodology
The missile target (MT) is erected at 5m height
with respect to seabed and downrange �000m
along the line of fire. It simulates a low flying
missile flying at �000m altitude. It is an extended
target of cylindrical shape with 0.2m radius,
5.0m length and made of aluminum alloy sheet.
Proper distance is maintained between the
target and gun by use of distometer/laser range
finder and the line of fire is chosen considering
the range safety in to account. MT is erected
in a horizontal way such that its body axis and
gun axis lie in a vertical plane. DGPS is used
to measure the altitude of target and that of
camera location so that camera can be adjusted
to match its axis to that of MT and both axes
lie in one horizontal straight line. Measurement
accuracy down to 0.0�m is achieved in this DGPS.
It helps to know the exact separation between
camera and target and also to ascertain both
are at same height. High-speed digital CMOS
camera, Speed Cam Visario, is used where a
maximum resolution of �536x�02� pixel is
achieved at �000pps. Its sensor has got square
pixel of size ��µm x��µm.Image acquisition is
performed through an external trigger, a flash-
trigger, that picks up muzzle flash of the gun
during firing and initiates image acquisition.
This trigger time is considered as reference time
t0 at which projectile leaves the muzzle. Camera
records the event in the post-trigger mode to
facilitate determining time to burst of fuze
functioning over MT which is obtained through
off-line video analysis. In a series of functioning
rounds, burst time is determined for each round
and then mean burst time is calculated. This is
probable because in a firing series, parameters
like charge mass, charge temperature, gun
elevation etc are maintained constant through
out. Minimum distance of the projectile with
respect to MT needs to be calculated during
flight for miss distance calculation. Ideally in
�0mm proximity ammunitions, shell is designed
to function within 3m radius with respect to
MT body axis. So a field-of-view (FOV) of more
than 3.0m radius around MT longitudinal axis is
chosen using suitable optics.
Contributed Paper
50 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
2.1.2 experimental set-up & observations
The experimental lay out is shown in Fig.�..
Burst time is calculated for both shells and mean
time to burst is found out (typically in the order
of 976ms). The functioning of the two rounds
is affirmed well within three meter radius with
respect to MT. Subsequently two inert shells
are fired which simulate non-functioning ones.
These shells are also captured in flight. Separation
between MT center and the shell at 976ms from
reference time t0 is calculated from offline image
analysis and found out to be 0.37�m in one case
as shown in Fig.3.
C1 – in-line high-speed digital camera; C2 –range
camera; PC – camera control computer; T- flash
trigger; MT- missile target
Fig.� Schematic set up of experimental lay out
The in-line high-speed digital camera C� and
MT are separated by �000m and a telephoto lens
of �00mm focal length is used to have a spatial
resolution of �3mm/pixel in the object plane.
It ensures a 3x3 pixels image point of �0mm
proximity fuze at the target plane that can be
well resolved. To ascertain that shell is functioning
within the miss distance zone of the target, one
conventional camera C2, called as range camera, is
placed at right angle to MT and also maintaining
co-planarity to have equal height with respect
to MT. In case of functioning, the co-ordinates of
point of functioning is determined from both C�
and C2 data which read two orthogonal planes of
functioning.
Initially two fuze shells are fired to
function over MT that is confirmed by range
camera C2.Orthogonal views of inline and range
camera are shown in Fig. 2.
(a)
(b)
Fig. 2. Functioning of fuze (a) Perpendicular view
by C2 (b) In-line view by C�
Fig. 3 Measurement of miss distance with respect
to MT center
2.2 Determination of rate of fire of aK630
naval Weapon
AK-630 weapon of Russian origin has six barrels of
30mm caliber and determination of its high rate
of fire is crucial for its acceptance.
2.2.1. methodology
Rate of fire of the order �500 rounds/min has
been determined by an innovative layout by firing
a salvo of 30 rounds on to a witness target and
simultaneously recording target hit points by a
conventional video camera. The cumulative impact
on the target is calculated over time through
frame by frame analysis leading to estimation of
rate of fire. The same has also been attempted by
acoustics method and the results are in very close
agreement and reproducible.
2.2.2. experimental set up & observations
One witnessing target; a ply board of size
2.5mX2.5m, is erected at �00m downrange from
muzzle in the transverse plane with respect to the
line of fire. Conventional video camera is placed
adjacent to the gun to image the witnessing target
and to find out the number of shots crossing the
very target plane over time from their impacts on
target. Schematic set up for rate of fire studies of
AK-630 weapon is shown in Fig.�.
Here an IT ½” CCD camera is used with an
objective lens of focal length ��0mm. It covers a
field of view of 3.5mX2.66 m in the target plane.
Its sensor has got a resolution of 6�0 x ��0 pixels
which corresponds to 5mm resolution in the
target plane. Camera is powered form a camera
control unit (CCU) which is connected to a PC for
display and image analysis. Camera is positioned
on a platform to match with the line of fire and
its image center coincides with the witnessing
target center. The main aim is to look at the cluster
of impacts from a right angle position. Passive
imaging is incorporated in the total process and
due care is taken to image impact points. The
impact points are well defined and accounted for
its quanta unless otherwise there is a complete
superimposition of one above the other.
T
C
GUN
PC
CCU
C-camera, CCU-camera control unit, T-witnessing target
Fig.� Schematic set-up for recording Rate of Fire of weapon
(a)
(b)
Fig.5. a) Witnessing target showing impact points, b) graph showing impact points vs. time
Cluster of 30 munitions is fired in a salvo mode and
their impacts are shown on the witnessing target
in Fig.5.(a).Then offline analysis is performed to
obtain rate of fire which has been depicted in
Fig.5.(b). Here cumulative impacts over time is
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 5�
Proceedings of the National Seminar : 23 Nov 20�0
2.1.2 experimental set-up & observations
The experimental lay out is shown in Fig.�..
Burst time is calculated for both shells and mean
time to burst is found out (typically in the order
of 976ms). The functioning of the two rounds
is affirmed well within three meter radius with
respect to MT. Subsequently two inert shells
are fired which simulate non-functioning ones.
These shells are also captured in flight. Separation
between MT center and the shell at 976ms from
reference time t0 is calculated from offline image
analysis and found out to be 0.37�m in one case
as shown in Fig.3.
C1 – in-line high-speed digital camera; C2 –range
camera; PC – camera control computer; T- flash
trigger; MT- missile target
Fig.� Schematic set up of experimental lay out
The in-line high-speed digital camera C� and
MT are separated by �000m and a telephoto lens
of �00mm focal length is used to have a spatial
resolution of �3mm/pixel in the object plane.
It ensures a 3x3 pixels image point of �0mm
proximity fuze at the target plane that can be
well resolved. To ascertain that shell is functioning
within the miss distance zone of the target, one
conventional camera C2, called as range camera, is
placed at right angle to MT and also maintaining
co-planarity to have equal height with respect
to MT. In case of functioning, the co-ordinates of
point of functioning is determined from both C�
and C2 data which read two orthogonal planes of
functioning.
Initially two fuze shells are fired to
function over MT that is confirmed by range
camera C2.Orthogonal views of inline and range
camera are shown in Fig. 2.
(a)
(b)
Fig. 2. Functioning of fuze (a) Perpendicular view
by C2 (b) In-line view by C�
Fig. 3 Measurement of miss distance with respect
to MT center
2.2 Determination of rate of fire of aK630
naval Weapon
AK-630 weapon of Russian origin has six barrels of
30mm caliber and determination of its high rate
of fire is crucial for its acceptance.
2.2.1. methodology
Rate of fire of the order �500 rounds/min has
been determined by an innovative layout by firing
a salvo of 30 rounds on to a witness target and
simultaneously recording target hit points by a
conventional video camera. The cumulative impact
on the target is calculated over time through
frame by frame analysis leading to estimation of
rate of fire. The same has also been attempted by
acoustics method and the results are in very close
agreement and reproducible.
2.2.2. experimental set up & observations
One witnessing target; a ply board of size
2.5mX2.5m, is erected at �00m downrange from
muzzle in the transverse plane with respect to the
line of fire. Conventional video camera is placed
adjacent to the gun to image the witnessing target
and to find out the number of shots crossing the
very target plane over time from their impacts on
target. Schematic set up for rate of fire studies of
AK-630 weapon is shown in Fig.�.
Here an IT ½” CCD camera is used with an
objective lens of focal length ��0mm. It covers a
field of view of 3.5mX2.66 m in the target plane.
Its sensor has got a resolution of 6�0 x ��0 pixels
which corresponds to 5mm resolution in the
target plane. Camera is powered form a camera
control unit (CCU) which is connected to a PC for
display and image analysis. Camera is positioned
on a platform to match with the line of fire and
its image center coincides with the witnessing
target center. The main aim is to look at the cluster
of impacts from a right angle position. Passive
imaging is incorporated in the total process and
due care is taken to image impact points. The
impact points are well defined and accounted for
its quanta unless otherwise there is a complete
superimposition of one above the other.
T
C
GUN
PC
CCU
C-camera, CCU-camera control unit, T-witnessing target
Fig.� Schematic set-up for recording Rate of Fire of weapon
(a)
(b)
Fig.5. a) Witnessing target showing impact points, b) graph showing impact points vs. time
Cluster of 30 munitions is fired in a salvo mode and
their impacts are shown on the witnessing target
in Fig.5.(a).Then offline analysis is performed to
obtain rate of fire which has been depicted in
Fig.5.(b). Here cumulative impacts over time is
52 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
plotted which shows a linear curve .It means a
uniform rate of fire is obtained in this weapon and
from its slope rate of fire is calculated. This is found
out to be ��52 shots/min and has got a very close
match with the one taken by normal acoustic
method.
2.3 Determination of attitude of Projectile
before impact on target
The attitude of a projectile at the point of impact
on armor affects the depth of penetration3.
Methodology for recording the attitude of the
projectile before its impact on target has been
developed by single shot capture of images
of the projectile in two orthogonal planes
simultaneously. It provides projectile orientation
both in vertical and horizontal planes leading
to measurement of both yaw and pitch angles
resulting its determination of attitude at the very
instance of space and time.
2.3.1 methodology
Imaging the projectile in two orthogonal planes
simultaneously, both horizontal and vertical,
determines both pitch and yaw angles from which
the attitude angle (angle of attack) is determined
as shown in Fig.6.
Let ∈ be the angle of attitude which is defined in 3-
D as shown above. It is resolved in two orthogonal
planes resulting є v and є
h which are yaw and
pitch angles respectively considering paraxial
firing as practiced during armor testing. Here the
angle of attitude є is expressed as
є = tan-� є (tan2 є v + tan 2 є
h )
Further tan є v and tan є
h are slopes of the
projectile image body axis captured in the vertical
and horizontal planes respectively.
2.3.2 experimental set up & observations
The mirror set up is positioned along the line
of fire such that longitudinal axis of the mirror
and the line of fire lie in the same vertical plane
of camera FOV. Here the projectile is allowed to
pass within a hollow cylindrical object containing
the very mirror at �5º with respect to the vertical
plane. Both direct and mirror images are recorded
simultaneously by a single ICCD camera. In this
case SVR II Ballistic Range Camera is used as
shown in Fig.7.
Fig. 6 Vector diagram for defining angle of attack є of the projectile in terms of vertical and horizontal angles є
v and є
h representing yaw and pitch
respectively
Gun Mirror
T
S
PC CAM
Fig. 7 Schematic set up for projectile attitude studies: T- optical trigger (sky screen); S-Xenon strobe
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 53
Proceedings of the National Seminar : 23 Nov 20�0
Optical trigger, a sky screen, placed under line
of fire and close to the mirror set up, is used as
external trigger for capture of shot image within
the camera FOV after incorporating appropriate
delay to the Xenon strobe, used as illuminating
source. The attitude of a �0mm AP shot before
impact on armor at 50m has been generated and
image is shown in Fig.�.
found to be less than 5º.This technique can be
used for different types of AP shots. During set up
perpendicularity of the camera to the line of fire
as well to the longitudinal axis of the mirror has
to be done very carefully. To achieve this, simple
pendulum can be used as a test image where
center of circles of both the direct and mirror
images should lie in one vertical line.
3. conclUsion
Techniques for estimation of miss distance
measurement of �0mm proximity fuze ,rate of
fire of AK630 weapon and attitude of a �0mm AP
shot have been established and are being used
currently in day to day trial activities.
acKnoWleDGement
The authors wish to express their sincere thanks
to Maj Gen Praveen Mathur , Director, Proof &
Experimental Establishment, Chandipur for his
encouragement and permission to publish this
paper.
Fig.� Orthogonal images of �0mm shot captured
in SVR II: Top-direct image (vertical plane) &
bottom-mirror image (horizontal plane)
In this case є v
and є h are found to be �.�º and
2.��º respectively and є is found out as 3.0�º.
Three shots were fired and in all the cases є was
references
[�] T K Biswal et al. “Dynamic test & evaluation methodologies for measurement of critical test parameters of armaments: case studies”, National Conf on Advances in Armament Technologies (NCAAT),ARDE, Pune Nov 200�.
[2] T.K. Biswal et al. “ Miss distance studies of �0mm proximity fuze with respect to anti-missile target using high-speed videography”, NACORT-2006, ITR (DRDO), Balasore.
[3] Manfred Held “Impact parameters of projectiles”, Propellants, Explosives, Pyrotechnics 2�,2��-2�6,�999.
5� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
MODELLING INTERIOR BALLISTIC PRESSURE GRADIENT PHENOMENON INSIDE GUN BARREL SYSTEM
KK Chanda , Smt NN Jenab and MK Dasc
a,bProof & Experimental Establishment, Chandipur, Balasore, Orissa-756 025ae-mail: [email protected]
be-mail: [email protected] of Physics, NC College, Jajpur Cuttack, Orissa
ce-mail: [email protected]
ABSTRACT
The science of interior ballistics is concerned with the converting some form of stored
energy into significant kinetic energy and transmitted to the projectile in gun systems,
or the work to be done against external forces. Interior ballistics processes are a very
complex phenomenon. Performance of a gun propellant is assessed through two
important parameters, pressure and velocity and carried out dynamic trials or actual
gun firings. The paper discusses with various modeling approach for pressure gradient
distribution phenomenon in the space behind the projectile and analyzed with the
availabled results of 30mm caliber cannon experimental firings. Lastly, performance of
a higher caliber weapon has been depicted as an example.
Keywords: gun system, ballistics, interior/internal ballistics, pressure gradient, projectile base pressure,
breech pressure, and gun propellant.
1. introDUction
1.1 THE SCIENCE OF GUN PROPULSION –
INTERIOR BALLISTICS
The science of interior ballistics is concerned with
the propulsion of a projectile along the tube of a
weapon by the gas pressure on the base of the
projectile, or, for rockets, by the backward exhaust
of the gas jet. Interior ballistics processes are a very
complex phenomenon. The basic interior ballistic
process may be considered as a heat engine, which
converts some form of stored energy (classically,
chemical energy of a solid propellant released
upon burning) into significant kinetic energy
of a launch package in a very short timeframe
and employing a launch system that occupies
limited space. The interior ballistic cycle includes
the entire phenomena-taking place during the
tube phases of gun firing. The kinetic energy
transmitted to the projectile in gun systems, or
the work to be done against external forces such
as the deformation force of the rotating band, is
produced by an exothermic and gas producing
reaction of solid propellants. Most processes of
warheads and ballistics – interior, exterior and
terminal – are very dependent on the use and
properties of energetic materials – propellants
and explosives – for their functioning. The very
nature of this highly dynamic launch environment
defines the fundamental problem for the gun
interior ballistician – managing the competition
between the production of gases from the
burning propellant and the volume to put them
in as the projectile moves down the bore, so as
to maximize the conversion of stored chemical
energy of the propellant to kinetic energy of the
projectile at muzzle exit, Figure �.
As shown in Figure 2, the challenge for more
performance thus translates into one of
increasing the area under the pressure vs. travel
curve without exceeding the maximum pressure
limits of the system, be they imposed by the gun
tube, the recoil system, or the projectile itself.
Produce the gases too rapidly and excessive
pressurization occurs; too slowly, the propellant
is not all burned and/or expansion of combustion
gases is limited, reducing the extraction of energy
to accelerate the projectile. Proper programming
of energy release, however, broadens the curve
and increases projectile kinetic energy at the
muzzle. This interesting process thus defines
the fundamental tasking to interior ballisticians
throughout history: increasing interior ballistic
performance by (i) increasing the total energy
available to the propulsion system and, equally
important, (ii) tailoring the release of this energy,
both temporarily and spatially, to maximize its
transfer to the projectile. Numerous contributions,
both experimental and theoretical, have addressed
this grand challenge for centuries.
1.2 INTERIOR BALLISTIC MODEL
The fundamental books and documents covering
the state of theoretical and practical knowledge
on propellant combustion, as a first approximation
recommend the burning law expressed as
exponential dependence on pressure
r = β • pα (�)
where α is the pressure index and β is the burning
rate constant of the propellant composition.
Above-mentioned equation is known as Saint
Robert’s equation. The burning rate law usually
approximates the burning rate of a propellant
where the value of pressure index is �. It means
Figure 1: Conversion of chemical energy stored in the propellant into kinetic energy in the projectile
Figure 2: Increasing the area under the pressure vs. travel curve without exceeding system pressure limits
Contributed Paper
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 55
Proceedings of the National Seminar : 23 Nov 20�0
MODELLING INTERIOR BALLISTIC PRESSURE GRADIENT PHENOMENON INSIDE GUN BARREL SYSTEM
KK Chanda , Smt NN Jenab and MK Dasc
a,bProof & Experimental Establishment, Chandipur, Balasore, Orissa-756 025ae-mail: [email protected]
be-mail: [email protected] of Physics, NC College, Jajpur Cuttack, Orissa
ce-mail: [email protected]
ABSTRACT
The science of interior ballistics is concerned with the converting some form of stored
energy into significant kinetic energy and transmitted to the projectile in gun systems,
or the work to be done against external forces. Interior ballistics processes are a very
complex phenomenon. Performance of a gun propellant is assessed through two
important parameters, pressure and velocity and carried out dynamic trials or actual
gun firings. The paper discusses with various modeling approach for pressure gradient
distribution phenomenon in the space behind the projectile and analyzed with the
availabled results of 30mm caliber cannon experimental firings. Lastly, performance of
a higher caliber weapon has been depicted as an example.
Keywords: gun system, ballistics, interior/internal ballistics, pressure gradient, projectile base pressure,
breech pressure, and gun propellant.
1. introDUction
1.1 THE SCIENCE OF GUN PROPULSION –
INTERIOR BALLISTICS
The science of interior ballistics is concerned with
the propulsion of a projectile along the tube of a
weapon by the gas pressure on the base of the
projectile, or, for rockets, by the backward exhaust
of the gas jet. Interior ballistics processes are a very
complex phenomenon. The basic interior ballistic
process may be considered as a heat engine, which
converts some form of stored energy (classically,
chemical energy of a solid propellant released
upon burning) into significant kinetic energy
of a launch package in a very short timeframe
and employing a launch system that occupies
limited space. The interior ballistic cycle includes
the entire phenomena-taking place during the
tube phases of gun firing. The kinetic energy
transmitted to the projectile in gun systems, or
the work to be done against external forces such
as the deformation force of the rotating band, is
produced by an exothermic and gas producing
reaction of solid propellants. Most processes of
warheads and ballistics – interior, exterior and
terminal – are very dependent on the use and
properties of energetic materials – propellants
and explosives – for their functioning. The very
nature of this highly dynamic launch environment
defines the fundamental problem for the gun
interior ballistician – managing the competition
between the production of gases from the
burning propellant and the volume to put them
in as the projectile moves down the bore, so as
to maximize the conversion of stored chemical
energy of the propellant to kinetic energy of the
projectile at muzzle exit, Figure �.
As shown in Figure 2, the challenge for more
performance thus translates into one of
increasing the area under the pressure vs. travel
curve without exceeding the maximum pressure
limits of the system, be they imposed by the gun
tube, the recoil system, or the projectile itself.
Produce the gases too rapidly and excessive
pressurization occurs; too slowly, the propellant
is not all burned and/or expansion of combustion
gases is limited, reducing the extraction of energy
to accelerate the projectile. Proper programming
of energy release, however, broadens the curve
and increases projectile kinetic energy at the
muzzle. This interesting process thus defines
the fundamental tasking to interior ballisticians
throughout history: increasing interior ballistic
performance by (i) increasing the total energy
available to the propulsion system and, equally
important, (ii) tailoring the release of this energy,
both temporarily and spatially, to maximize its
transfer to the projectile. Numerous contributions,
both experimental and theoretical, have addressed
this grand challenge for centuries.
1.2 INTERIOR BALLISTIC MODEL
The fundamental books and documents covering
the state of theoretical and practical knowledge
on propellant combustion, as a first approximation
recommend the burning law expressed as
exponential dependence on pressure
r = β • pα (�)
where α is the pressure index and β is the burning
rate constant of the propellant composition.
Above-mentioned equation is known as Saint
Robert’s equation. The burning rate law usually
approximates the burning rate of a propellant
where the value of pressure index is �. It means
Figure 1: Conversion of chemical energy stored in the propellant into kinetic energy in the projectile
Figure 2: Increasing the area under the pressure vs. travel curve without exceeding system pressure limits
Contributed Paper
56 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
that the burning rate and pressure rise in direct
proportion. Then the burning rate law is expressed
as linear dependence on pressure
r = r� • p , (2)
where it is assumed that value of coefficient r1 is
constant (for given type of propellant) regardless
of value of propellant gas pressure.
There are several interior ballistic models,
starting with classic models, up to so-called 3rd
generation models, which cover a wide area of
hypotheses, more or less realistic. In classic models,
the solution is entirely analytical, supposing
that all the physicochemical phenomena can be
modeled by polynomial or differential equations,
with known coefficients. For example, let us
consider the Muraour law (1st generation model-0
dimensional model) for burning rate of propellant
grain as a function of pressure:
v(p) = α • pn + b (3)
These models are no longer satisfied, while
the real behaviour of burning propellant is
far away from this hypothesis. The modern
models use numerical analysis and allow to skip
some analytical expressions, instead of using
experimental data like form function and burning
rate as input data in a source code, but this doesn’t
let us to avoid a number of simplifying hypotheses.
In the 2nd generation models, the pressure behind
projectile and the pressure on the breech are no
longer calculated based on the medium pressure
measured with the piezoelectric transducer. So, the
space between breechblock and the projectile is
divised into a number of finite elements (volumes)
and the pressure is a determined using CFD
algorithm. In 3rd generation models the biphasic
flow is considered, as the gases generation
process is not instantaneous, but there is, in the
first part of burning process, a mixture between
gases and unburned or partial burned propellant
grains (which is beyond the scope of discussion in
this paper).
Starting point of the model proposed is
the perspective on the propellant and burning
gases state. In both, closed vessel and gun barrel,
the dual phase (propellant-burning gases)
physical state can by defined at any moment of
time by some global parameters as pressure,
temperature, burned propellant mass fraction,
relative propellant density. The biphasic state may
be expressed by the equations bellow:
Eb = E
b ( P, Ψ , T, ∆ ) (�)
Eg= E
g ( P, Ψ , T, ∆ )
where: Eb - dual phase state in closed vessel; E
g -
dual phase state in gun barrel;
P - gases pressure; ψ - burned propellant mass
fraction; T - gases temperature;
∆ - relative propellant density (propellant mass
versus closed vessel or barrel internal volume ratio.
Further, for sake of simplicity and
assuming the hypothesis of closed vessel tests
data with similar heat loses as in gun barrel, we
could neglect the temperature evolution and its
effects. In this case, the equation (�) becomes:
Eb = E
b ( P, Ψ , T, ∆ ) (5)
Eg= E
g ( P, Ψ , T, ∆ )
Typical evolutions of gun barrel chamber pressure
and projectile velocity are shown in Figure 3.
Figure 3: Typical gun barrel pressure and projectile velocity time evolution
In the field of interior ballistics of guns, one of
the objectives of the studies carried out is the
development of numerical tools to understand
the behaviour of complex ammunition. Over
the past three decades, the field of interior
ballistic modelling has undergone a number of
major advances with the continual increase of
computing power. Before, lumped-parameter
models were used to perform large parametric
interior ballistics studies and they are still used for
most basic interior ballistics systems and charge
design studies.
2. mathematical moDellinG
When the projectile gains velocity, a pressure
gradient exists in the gun barrel due to hot gases,
acceleration of unburnt propellant and friction at
the bore surface. The ratio of breech pressure to
base pressure is a function of projectile velocity
and is given by Kent. If pressure at the projectile
base causing the motion is known, then velocity
time profile of the projectile can be obtained
by applying Newton’s equation of motion.
Kent’s Equation 6 has been used to compute
the instantaneous base pressures from actually
measured instantaneous breech pressure values.
The relationship between pd and p
s , comes as
hydrodynamic problem of the gun. The ratio of
pd
/ ps , derived by Kent is:
pd =� +
� ( ω )- � ( ω )2
+ ( �
+ � )( ω ) 2
+... (6)p
s 2 m
q 2�φ
� m
q �0φ
� 360φ
�2 m
q
where ω is the charge weight, mq is the projectile
weight and ϕ� is the ratio of specific heats or
losses coefficient. The value of ϕ� is calculated
from chemical composition of the propellant. The
value of ϕ� for LOVA propellant is �.26�6 and for
NQ/M propellant is �.250�.
During the movement of a projectile
inside a barrel is created a pressure gradient
between the barrel breech and the projectile base
due to the difference in velocities of propellant
gases at the breech and the projectile base, Figure
�. This pressure gradient belongs among factors
that significantly affect not only interior ballistic
calculations but also the design of projectiles. The
pressure gradient is usually characterized by the
ratio of the breech pressure pd and the projectile
base pressure ps.
Figure 4: Pressure gradient in the space behind a projectile p- ballistic pressure, v- velocity of projectile, l- projectile trajectory
Figure 5: Schematic of cylindrical cartridge chamber (lkom = l0) lkom - length of cartridge chamber, l0 - length of initial combustion volume
There are number of models describing the
pressure gradient but without any comparison
with experimental results. Most of the models
are relatively old and were created for ballistic
systems of lower performance, e.g. howitzers.
There is not any study analysing the suitability
of these models for modern medium calibre and
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 57
Proceedings of the National Seminar : 23 Nov 20�0
that the burning rate and pressure rise in direct
proportion. Then the burning rate law is expressed
as linear dependence on pressure
r = r� • p , (2)
where it is assumed that value of coefficient r1 is
constant (for given type of propellant) regardless
of value of propellant gas pressure.
There are several interior ballistic models,
starting with classic models, up to so-called 3rd
generation models, which cover a wide area of
hypotheses, more or less realistic. In classic models,
the solution is entirely analytical, supposing
that all the physicochemical phenomena can be
modeled by polynomial or differential equations,
with known coefficients. For example, let us
consider the Muraour law (1st generation model-0
dimensional model) for burning rate of propellant
grain as a function of pressure:
v(p) = α • pn + b (3)
These models are no longer satisfied, while
the real behaviour of burning propellant is
far away from this hypothesis. The modern
models use numerical analysis and allow to skip
some analytical expressions, instead of using
experimental data like form function and burning
rate as input data in a source code, but this doesn’t
let us to avoid a number of simplifying hypotheses.
In the 2nd generation models, the pressure behind
projectile and the pressure on the breech are no
longer calculated based on the medium pressure
measured with the piezoelectric transducer. So, the
space between breechblock and the projectile is
divised into a number of finite elements (volumes)
and the pressure is a determined using CFD
algorithm. In 3rd generation models the biphasic
flow is considered, as the gases generation
process is not instantaneous, but there is, in the
first part of burning process, a mixture between
gases and unburned or partial burned propellant
grains (which is beyond the scope of discussion in
this paper).
Starting point of the model proposed is
the perspective on the propellant and burning
gases state. In both, closed vessel and gun barrel,
the dual phase (propellant-burning gases)
physical state can by defined at any moment of
time by some global parameters as pressure,
temperature, burned propellant mass fraction,
relative propellant density. The biphasic state may
be expressed by the equations bellow:
Eb = E
b ( P, Ψ , T, ∆ ) (�)
Eg= E
g ( P, Ψ , T, ∆ )
where: Eb - dual phase state in closed vessel; E
g -
dual phase state in gun barrel;
P - gases pressure; ψ - burned propellant mass
fraction; T - gases temperature;
∆ - relative propellant density (propellant mass
versus closed vessel or barrel internal volume ratio.
Further, for sake of simplicity and
assuming the hypothesis of closed vessel tests
data with similar heat loses as in gun barrel, we
could neglect the temperature evolution and its
effects. In this case, the equation (�) becomes:
Eb = E
b ( P, Ψ , T, ∆ ) (5)
Eg= E
g ( P, Ψ , T, ∆ )
Typical evolutions of gun barrel chamber pressure
and projectile velocity are shown in Figure 3.
Figure 3: Typical gun barrel pressure and projectile velocity time evolution
In the field of interior ballistics of guns, one of
the objectives of the studies carried out is the
development of numerical tools to understand
the behaviour of complex ammunition. Over
the past three decades, the field of interior
ballistic modelling has undergone a number of
major advances with the continual increase of
computing power. Before, lumped-parameter
models were used to perform large parametric
interior ballistics studies and they are still used for
most basic interior ballistics systems and charge
design studies.
2. mathematical moDellinG
When the projectile gains velocity, a pressure
gradient exists in the gun barrel due to hot gases,
acceleration of unburnt propellant and friction at
the bore surface. The ratio of breech pressure to
base pressure is a function of projectile velocity
and is given by Kent. If pressure at the projectile
base causing the motion is known, then velocity
time profile of the projectile can be obtained
by applying Newton’s equation of motion.
Kent’s Equation 6 has been used to compute
the instantaneous base pressures from actually
measured instantaneous breech pressure values.
The relationship between pd and p
s , comes as
hydrodynamic problem of the gun. The ratio of
pd
/ ps , derived by Kent is:
pd =� +
� ( ω )- � ( ω )2
+ ( �
+ � )( ω ) 2
+... (6)p
s 2 m
q 2�φ
� m
q �0φ
� 360φ
�2 m
q
where ω is the charge weight, mq is the projectile
weight and ϕ� is the ratio of specific heats or
losses coefficient. The value of ϕ� is calculated
from chemical composition of the propellant. The
value of ϕ� for LOVA propellant is �.26�6 and for
NQ/M propellant is �.250�.
During the movement of a projectile
inside a barrel is created a pressure gradient
between the barrel breech and the projectile base
due to the difference in velocities of propellant
gases at the breech and the projectile base, Figure
�. This pressure gradient belongs among factors
that significantly affect not only interior ballistic
calculations but also the design of projectiles. The
pressure gradient is usually characterized by the
ratio of the breech pressure pd and the projectile
base pressure ps.
Figure 4: Pressure gradient in the space behind a projectile p- ballistic pressure, v- velocity of projectile, l- projectile trajectory
Figure 5: Schematic of cylindrical cartridge chamber (lkom = l0) lkom - length of cartridge chamber, l0 - length of initial combustion volume
There are number of models describing the
pressure gradient but without any comparison
with experimental results. Most of the models
are relatively old and were created for ballistic
systems of lower performance, e.g. howitzers.
There is not any study analysing the suitability
of these models for modern medium calibre and
5� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
high performance ballistic systems that still satisfy
the condition ω / mq < �.
2.1 moDels of PressUre GraDient
From the mentioned literatures the most
widespread models describing the pressure
gradient in the space behind a projectile were
chosen and were marked for needs of this paper as
model 1– 4. The fifth pressure distribution model
is used in the interior ballistic model described as
model STANAG �367.
Generally, it can be said, that basic element
of all analyzed models of pressure gradient is the
ratio , where: ω - mass of propellant charge, mq-
mass of the projectile.
2.1.1 moDel 1
This model is determined for ballistic systems with
a cylindrical cartridge chamber of the same area
of cross-section as area of cross-section of barrel,
Figure. 5.
In this model is the ratio of breech
pressure to the projectile base pressure expressed
as
(7)
trajectory. The dependency for common extent of
values ω / mq is shown in Figure. 7. From the Fig. 6
is clearly seen that according to the model 1 is the
pressure ratio pd / p
s directly proportional to the
ratio ω / mq.
ω2m
q
where: pd - breech pressure, p
s - projectile base
pressure, ω - mass of propellant charge, mq -
mass of projectile, φ� - losses coefficient (usually
between �.02 (howitzers and cannon) and �.�
(small arms �.05 – �.�).
In this model the ratio pd / p
s strongly
depends only on ratio ω / mq and remains constant
during the projectile movement inside the barrel,
i.e. the ratio is independent of the projectile
Figure 6: Dependency of pd / p
s on ratio ω / m
q and
φ1 = 1.1
Figure 7: Schematic of real cartridge chamber (lkom
≠ l
0)
2.1.2 moDel 2
A real cartridge chamber has usually bigger
diameter than the diameter of the barrel. This
model is based on the Model � and extended by
an effect of cartridge chamber shape. The effect of
the cartridge chamber shape is described by the
coefficient of cartridge chamber
shape , Figure 7.
The ratio of breech pressure pd to the projectile
base pressure ps is, in this model, described by
following empirical relation
(�)
where: χ ... coefficient of cartridge chamber shape,
k ... exponent (recommended value 0.3.
For calculation of exemplary courses
of pd / p
s were chosen typical extent of ratios ω /
mq from 0.2 to �.0, exponent k = 0.3 according to
recommendations from literature, and coefficient
φ1 = �.�. The obtained dependencies of p
d / p
s are
shown in Figure �.
The ratio pd / p
s is again independent of the projectile
trajectory and remains constant during the
projectile movement inside the barrel. Generally,
the ratio pd / p
s decreases with increasing cartridge
chamber shape coefficient χ and with decreasing
ratio ω / mq. Further the Figure shows that there
are, according to this model, certain combinations
of cartridge chamber shapes coefficients χ and
ratios ω / mq that gives p
d / p
s smaller than �; in
other words the breech pressure would be lower
than the projectile base one. This fact is, in case of
classical ballistic systems satisfying the condition
ω / mq < �, unexplainable.
2.1.3 moDel 3
The model 3 is also based on the model 1. This
time the model 1 is extended not only by the
effect of the shape of cartridge case chamber
χ but also by the effect of increasing volume of
the space behind the projectile expressed by the
projectile trajectory l and the pressure gradient is
written as
(9)
where: s - cross-sectional area of barrel, c0
- initial
volume of cartridge chamber.
The ratio pd / p
s was calculated again for
typical values and is shown in Figure 9. From the
figure is clearly seen that pd / p
s increases with the
trajectory of the projectile and also with ratio ω
/ mq. The increase of p
d / p
s is the steepest in the
beginning of projectile movement and later
becomes nearly constant.
Figure 8:Dependency of pd / p
s on cartridge chamber
shape coefficient χ(φ1 = 1.1, k = 0.3)
Figure 9: Dependency of pd / p
s on projectile’s
trajectory φ1 = 1.1, c0 / s = 0.4, χ = 1.75
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 59
Proceedings of the National Seminar : 23 Nov 20�0
high performance ballistic systems that still satisfy
the condition ω / mq < �.
2.1 moDels of PressUre GraDient
From the mentioned literatures the most
widespread models describing the pressure
gradient in the space behind a projectile were
chosen and were marked for needs of this paper as
model 1– 4. The fifth pressure distribution model
is used in the interior ballistic model described as
model STANAG �367.
Generally, it can be said, that basic element
of all analyzed models of pressure gradient is the
ratio , where: ω - mass of propellant charge, mq-
mass of the projectile.
2.1.1 moDel 1
This model is determined for ballistic systems with
a cylindrical cartridge chamber of the same area
of cross-section as area of cross-section of barrel,
Figure. 5.
In this model is the ratio of breech
pressure to the projectile base pressure expressed
as
(7)
trajectory. The dependency for common extent of
values ω / mq is shown in Figure. 7. From the Fig. 6
is clearly seen that according to the model 1 is the
pressure ratio pd / p
s directly proportional to the
ratio ω / mq.
ω2m
q
where: pd - breech pressure, p
s - projectile base
pressure, ω - mass of propellant charge, mq -
mass of projectile, φ� - losses coefficient (usually
between �.02 (howitzers and cannon) and �.�
(small arms �.05 – �.�).
In this model the ratio pd / p
s strongly
depends only on ratio ω / mq and remains constant
during the projectile movement inside the barrel,
i.e. the ratio is independent of the projectile
Figure 6: Dependency of pd / p
s on ratio ω / m
q and
φ1 = 1.1
Figure 7: Schematic of real cartridge chamber (lkom
≠ l
0)
2.1.2 moDel 2
A real cartridge chamber has usually bigger
diameter than the diameter of the barrel. This
model is based on the Model � and extended by
an effect of cartridge chamber shape. The effect of
the cartridge chamber shape is described by the
coefficient of cartridge chamber
shape , Figure 7.
The ratio of breech pressure pd to the projectile
base pressure ps is, in this model, described by
following empirical relation
(�)
where: χ ... coefficient of cartridge chamber shape,
k ... exponent (recommended value 0.3.
For calculation of exemplary courses
of pd / p
s were chosen typical extent of ratios ω /
mq from 0.2 to �.0, exponent k = 0.3 according to
recommendations from literature, and coefficient
φ1 = �.�. The obtained dependencies of p
d / p
s are
shown in Figure �.
The ratio pd / p
s is again independent of the projectile
trajectory and remains constant during the
projectile movement inside the barrel. Generally,
the ratio pd / p
s decreases with increasing cartridge
chamber shape coefficient χ and with decreasing
ratio ω / mq. Further the Figure shows that there
are, according to this model, certain combinations
of cartridge chamber shapes coefficients χ and
ratios ω / mq that gives p
d / p
s smaller than �; in
other words the breech pressure would be lower
than the projectile base one. This fact is, in case of
classical ballistic systems satisfying the condition
ω / mq < �, unexplainable.
2.1.3 moDel 3
The model 3 is also based on the model 1. This
time the model 1 is extended not only by the
effect of the shape of cartridge case chamber
χ but also by the effect of increasing volume of
the space behind the projectile expressed by the
projectile trajectory l and the pressure gradient is
written as
(9)
where: s - cross-sectional area of barrel, c0
- initial
volume of cartridge chamber.
The ratio pd / p
s was calculated again for
typical values and is shown in Figure 9. From the
figure is clearly seen that pd / p
s increases with the
trajectory of the projectile and also with ratio ω
/ mq. The increase of p
d / p
s is the steepest in the
beginning of projectile movement and later
becomes nearly constant.
Figure 8:Dependency of pd / p
s on cartridge chamber
shape coefficient χ(φ1 = 1.1, k = 0.3)
Figure 9: Dependency of pd / p
s on projectile’s
trajectory φ1 = 1.1, c0 / s = 0.4, χ = 1.75
60 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
2.1.4 moDel 4
As a last of the most used models of the pressure
gradient in the space behind the projectile that
takes into account except ω and mq, also χ and
relative projectile trajectory Λ. The ratio pd / p
s is
given by following relation
, where: (�0)
For calculation was again chosen the typical
extent of ratios ω / mq from 0.2 to �.0. The
obtained dependencies are shown in Figure �0.
The figure shows that pd / p
s increases with the
trajectory of the projectile and also with ratio ω
/ mq. The increase of p
d / p
s is again the steepest at
the beginning of projectile movement.
2.1.5 moDel stanaG 4367
In the Model STANAG �367 that is a part of the
interior ballistic model described is the ratio pd / p
s
given by the following relation
(��)
where: pr - resistance pressure against projectile
motion, pg -. pressure of gases ahead of projectile.
It can be seen that the ratio pd / p
s
depends not only on ω and mq but also on ratios
pr / ps and pd / p
s. All variables, with exception of
ω and mq, are time dependent, and so the ratio p
d
/ ps is not constant during projectile movement
inside the barrel. Typical course of ratio pd / p
s on
projectile’s trajectory is shown in Figure ��.
All previously analyzed models were used
for calculation of ratios pd / p
s for a ballistic systems
of calibre of 30 mm that was later also used for
experiments. Its ballistic characteristics were ω =
0.��5, mq = 0.3�9 kg, χ = �.9, ϕ
1 = �.03, c
0 = 2.3�9e-
� m3, s = 7.36�e-� m2. Obtained theoretical results
are summarized in Table �. Distances of individual
pressure gauges from back of barrel are shown in
Figure �3.
3. eXPeriments
For the validation of all previously mentioned
models of the pressure gradient in the space
behind the projectile it is necessary to know
the breech pressure pd and the projectile base
pressure ps. The experiment was focused on the
measurement of the pressure of propellant gases
at the breech and at the base of the projectile. The
measurement of the projectile base pressure was
realized by means of five piezoelectric pressure
Figure 10: Dependency of pd / p
s on projectile’s
trajectory φ1 = 1.1, c
0 / s = 0.4, χ = 1.75
Figure 11: Dependency of pd / p
s on projectile’s
trajectory
gauges placed along the barrel, Figure �3. The
projectile base pressure was read when the
projectile passed the individual pressure gauges.
For the experiment the ballistic testing weapon of
caliber of 30 mm weapon system was used. For the
test firings was used 30 mm practice ammunition,
ν0 = �000 m.s-�. The schematic of used ballistic
barrel with positions of piezoelectric pressure
gauges is shown in Figure �2.
corresponding breech pressures pd (Gauge No. �).
The evaluated values of both pressures together
with corresponding pressure ratios pd / p
s are
summarized in Table 2.
Figure 12: Schematic of ballistic barrel with positions of pressure gauges
Figure 13: Example of measured pressures
Example of measured pressures on all pressure
gauges is shown in Figure �3.
3.1 resUlts of eXPeriments their analysis
From obtained experimental data were determined
pressures at individual gauges (Gauges No. 2
- 6) at instant of projectile’s arrival ps and their
Table �: Results of calculations of pd / p
s from
individual models
Table 2: Results of experimental firings
Calculated and experimentally obtained ratios pd
/ ps are compared in Figure ��. At experimentally
obtained ratios pd / p
s are also shown their
corresponding standard deviations.
Figure 14: Comparison of experimental and calculated p
d / p
s
Figure 15: Trends on velocity and pressure profile due to wear
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 6�
Proceedings of the National Seminar : 23 Nov 20�0
2.1.4 moDel 4
As a last of the most used models of the pressure
gradient in the space behind the projectile that
takes into account except ω and mq, also χ and
relative projectile trajectory Λ. The ratio pd / p
s is
given by following relation
, where: (�0)
For calculation was again chosen the typical
extent of ratios ω / mq from 0.2 to �.0. The
obtained dependencies are shown in Figure �0.
The figure shows that pd / p
s increases with the
trajectory of the projectile and also with ratio ω
/ mq. The increase of p
d / p
s is again the steepest at
the beginning of projectile movement.
2.1.5 moDel stanaG 4367
In the Model STANAG �367 that is a part of the
interior ballistic model described is the ratio pd / p
s
given by the following relation
(��)
where: pr - resistance pressure against projectile
motion, pg -. pressure of gases ahead of projectile.
It can be seen that the ratio pd / p
s
depends not only on ω and mq but also on ratios
pr / ps and pd / p
s. All variables, with exception of
ω and mq, are time dependent, and so the ratio p
d
/ ps is not constant during projectile movement
inside the barrel. Typical course of ratio pd / p
s on
projectile’s trajectory is shown in Figure ��.
All previously analyzed models were used
for calculation of ratios pd / p
s for a ballistic systems
of calibre of 30 mm that was later also used for
experiments. Its ballistic characteristics were ω =
0.��5, mq = 0.3�9 kg, χ = �.9, ϕ
1 = �.03, c
0 = 2.3�9e-
� m3, s = 7.36�e-� m2. Obtained theoretical results
are summarized in Table �. Distances of individual
pressure gauges from back of barrel are shown in
Figure �3.
3. eXPeriments
For the validation of all previously mentioned
models of the pressure gradient in the space
behind the projectile it is necessary to know
the breech pressure pd and the projectile base
pressure ps. The experiment was focused on the
measurement of the pressure of propellant gases
at the breech and at the base of the projectile. The
measurement of the projectile base pressure was
realized by means of five piezoelectric pressure
Figure 10: Dependency of pd / p
s on projectile’s
trajectory φ1 = 1.1, c
0 / s = 0.4, χ = 1.75
Figure 11: Dependency of pd / p
s on projectile’s
trajectory
gauges placed along the barrel, Figure �3. The
projectile base pressure was read when the
projectile passed the individual pressure gauges.
For the experiment the ballistic testing weapon of
caliber of 30 mm weapon system was used. For the
test firings was used 30 mm practice ammunition,
ν0 = �000 m.s-�. The schematic of used ballistic
barrel with positions of piezoelectric pressure
gauges is shown in Figure �2.
corresponding breech pressures pd (Gauge No. �).
The evaluated values of both pressures together
with corresponding pressure ratios pd / p
s are
summarized in Table 2.
Figure 12: Schematic of ballistic barrel with positions of pressure gauges
Figure 13: Example of measured pressures
Example of measured pressures on all pressure
gauges is shown in Figure �3.
3.1 resUlts of eXPeriments their analysis
From obtained experimental data were determined
pressures at individual gauges (Gauges No. 2
- 6) at instant of projectile’s arrival ps and their
Table �: Results of calculations of pd / p
s from
individual models
Table 2: Results of experimental firings
Calculated and experimentally obtained ratios pd
/ ps are compared in Figure ��. At experimentally
obtained ratios pd / p
s are also shown their
corresponding standard deviations.
Figure 14: Comparison of experimental and calculated p
d / p
s
Figure 15: Trends on velocity and pressure profile due to wear
62 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
From comparison of results of calculations and
experimentally obtained pd / p
s follows that the
results of calculations are in good agreement with
experiment data, especially in the middle part
of the barrel. The only exception is the Model 2
whose results do not agree neither with results of
experiment nor with results of other models. This
disagreement is caused by inappropriate value of
the exponent k. From the comparison can be further
seen that at the beginning of projectile motion and
near the muzzle is the difference between results
of calculations and experiments more significant.
The Figure �5depicts the performances of the
�30mm higher caliber weapon system via pressure
vs velocity profile due to wear as an example.
4. conclUsion
We have described basic scientific concept of
interior ballistics and its attempted mathematical
models with its state-of-the-art CFD approach.
The existing models describing pressure gradient
phenomenon have been discussed and analyzed
with experimental data available in open literature
briefly. It is observed that the bigger difference
between measured and calculated ratios pd / ps near
the muzzle of the barrel can be explained by the leak
of propellant gases between barrel wall and driving
band that is at this stage of projectile movement
worn. Barrel wear usually also grows towards the
muzzle of barrel. The common disadvantage of all
the analyzed models is the fact that none of them
takes into account the leakage of propellant gases.
In other words, due to wear of the driving band is
changed the contact pressure between the driving
band and the barrel wall. The Model 2 requires more
suitable value of the exponent k to get into better
agreement with experimental results.
acKnoWleDGement
The authors are grateful to Maj Gen Praveen
Mathur, Director, Proof and Experimental
Establishment (PXE), Balasore, for his consent to
publish this paper.
references
[�] Understanding and predicting gun barrel erosion - Johnston A. J., Defence science and technology organisation, Edinburgh, Australia, 2005.
[2] Closed vessel ballistic assessment of gun propellant - DEF STAN �3–�9�/�, Ministry of Defence, Australia, �996.
[3] Propellants and Explosives - Kubota N., WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2007.
[�] NATO STANAG ���5, Definition and Determination of Ballistic Properties of Gun Propellants.
[5] Gun Propulsion Technology - Freedman, E., AIAA, �9��, American institute of aeronautics and astronautics, �9��. ISBN 0930�03207.
[6] Fluid-Structure Interaction in Interior Ballistic Environments- G.P Wren, S.E.Ray, T.E. Tezduyar and A. Hosangadi, �6th International Symposium on Ballistics, CA, September �996.
[7] Computation of In-bore Velocity-time and Travel-time profiles from Breech Pressure Measurements-D.K. Kankane and S.N. Ranade, Defence Science Journal Vol.53, No. �, October 2003.
[�] STANAG �367 Interior ballistic model with global parameters.
[9] Textbook of ballistics and gunnery-I & II. Editor LONGDON, L. W., London: Her Majesty’s stationery office, �9�7.
[�0] Burning surfaces evolution in solid propellants :a numerical model -J Szmelter and P Ortiz, Proc. IMechE Vol. 22� Part G: J. Aerospace Engineering, JAERO�02 © IMechE 2007.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 63
Proceedings of the National Seminar : 23 Nov 20�0
PREDICTION OF BALLISTIC PARAMETERS OF GUN AMMUNITION
Dusmant Kumar Jena
Proof and Experimental Establishment, Chandipur, Balasore-756025
ABSTRACT
During development and acceptance of ammunition a number of trial firings are
undertaken to ascertain if the desired parameters i.e. range and accuracy are achieved.
Trial firing of ammunition involves variety of activities e.g. transportation of ammunition
from the manufacturer to the firing range, temporary storage at the range, provisioning
of requisite instrumentation at the range, positioning of trial team etc. and in addition,
co-ordination between a no. of external agencies. Thus, inordinate delays takes place
during development of ammunition stores. Besides, the cost factor also goes up with
repetition of the trials. Therefore, it would be highly beneficial to utilize the advanced
computing facility available today to simulate and predict the parameters without
actually firing the ammunition. And once the simulation confirms the achievement of
desired parameters a trial firing may be conducted to validate the simulation.
Key Words : Ammunition, Simulation, Propellant, Fluid Dynamics, Projectile
introDUction :
During development and acceptance of
ammunition a number of trial firings are
undertaken to ascertain if the desired parameters
i.e. range and accuracy are achieved. Trial firing
of ammunition involves variety of activities
e.g. transportation of ammunition from the
manufacturer to the firing range, temporary
storage at the range, provisioning of requisite
instrumentation at the range, positioning of trial
team etc. and in addition, co-ordination between
a no. of external agencies. Thus, inordinate delays
takes place during development of ammunition
stores. Besides, the cost factor also goes up
with repetition of the trials. Therefore, it would
be highly beneficial to utilize the advanced
computing facility available today to simulate and
Contributed Paper
6� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
predict the parameters without actually firing the
ammunition. And once the simulation confirms the
achievement of desired parameters a trial firing
may be conducted to validate the simulation.
internal Ballistics :
The firing sequence of a gun commences with the
ignition of primer of the cartridge either electrically
or by percussion. The hot gases generated by
ignition of the primer in turn initiates combustion
of propellant. At this stage the gun chamber is
virtually sealed by the projectile. So, the gases and
the energy liberated by the primer and propellant
get confined to a limited volume. Thus, resulting
in rapid increase in pressure and the temperature
within the chamber. The burning rate of propellant
is proportional to the chamber pressure. Therefore,
increase in chamber pressure leads to further
increase in the rate of gas generation. This process
would continue until the gun gets exploded.
This doesn’t, however, happen practically as the
projectile (which is crimped to the cartridge case)
starts moving along the barrel as soon as the
chamber pressure reaches a threshold level known
as shot-start pressure(as shown in graph).
With the projectile moving ahead
the volume to be filled in by the high pressure
propellant gasses also increases. At this point the
propellant is still burning and increase in volume
is much lesser compared to generation of high
pressure propellant gas. Therefore, the resultant
pressure keeps on increasing until the space
being created behind the accelerating projectile
exceeds the rate at which high pressure gas is
being produced. Thereafter, (after reaching the
maximum pressure) the pressure begins to fall.
The next stage is the all-burnt position
where the burning of propellant is completed.
Still, there remains a considerable amount of
pressure in the gun for the remaining motion
of the projectile along the bore. Therefore, the
projectile continues to accelerate even after the
all-burnt position. The moment the projectile
leaves the gun, the chamber pressure reduces to
about one sixth of the peak pressure.
Eg is the kinetic energy of the propellant gas
motion,
Eu is the kinetic energy of the unburnt
propellant motion,
Er is the kinetic energy due to recoil of the
gun,
Eb is the heat energy lost to the barrel,
Eh is the residual heat energy in the propellant
gasses,
Es is the strain energy used in expanding the
barrel,
Ef is the energy lost in engraving the driving
band and the overcoming friction in the
bore.
intermeDiate Ballistics :
As the projectile moves down the gun barrel, it
compresses the air ahead of it. The gun barrel acts
like a shock tube in which a near-planar shock
forms. When this shock exits the muzzle, it forms
a spherical shock wave . As the projectile moves
faster and faster in the barrel a second precursor
will be formed. This precursor moves faster than the
first one. The under-oxidised propellant gas reacts
with oxygen present in the precursor flow field
which gives rise to pre-flash. Several microseconds
after the precursor shock appears but before the
projectile exit a bottle shaped structure known as
bottle shock and an annular vortex is formed. All
these phenomena ultimately result in a bulge of
propellant gases through the precursor shock both
preceding and following the projectile.
eXterior Ballistics :
Once the projectile is out of the influence
of the propellant gases the flight of the
projectile is affected by the factors associated
with the atmosphere and the projectile itself.
The properties of atmosphere relevant to
the projectile flight trajectory are air density,
temperature, static pressure, viscosity and wind
speed direction. The projectile characteristics
which have some bearing on its flight trajectory
are its mass, caliber, shape and axial spin rate.
If the projectile happens to move in vacuum
the only force acting on a projectile in flight
is that due to gravitational acceleration. But in
air, there will be an additional force opposing
the forward motion of the projectile due to the
air resistance known as ‘drag’. The drag force
has three prime components which modify the
trajectory and these are : -
(a) Skin friction
(b) Pressure drag
(c) Yaw-dependent drag
methoDoloGy :
Computer models may be developed for internal,
intermediate and external ballistics for the
existing guns of caliber starting from 30mm to
�00mm. Thermophysics i.e. the quantification of
changes in a substance’s energy state caused by
changes in the physical state of the material and
Thermochemistry i.e. the quantification of changes
in a substance’s energy state caused by changes
in the chemical composition of the material’s
molecules and Thermodynamics i.e. the study
of energy transformations are to be taken into
account in detail while developing the model for
internal ballistics. Computational Fluid Dynamics
will be utilized to model the Intermediate ballistics.
There are two opposing forces acting
on a projectile within the gun barrel, namely
the propelling force due to the high pressure
propellant gas pushing the base of the projectile
and the frictional force between the projectile
and the bore (including the high resistance
due to engraving of Driving Band in the barrel
bore) opposing the motion of the projectile.
Additionally, the reaction between the projectile
and the rifling of a rifled gun translates a small
part of the propelling force into a torque which
causes the projectile to rotate. Any physical
system has to obey the principle of conservation
of energy. So, the total energy liberated in the
form of propellant gasses at high temperature,
which gets converted into other forms remains
the same. Therefore it may be written that : -
Et = E
p+E
g+E
u+E
r+E
b+E
n+E
s+E
f
Where Ep is the kinetic energy due to the
projectile motion,
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 65
Proceedings of the National Seminar : 23 Nov 20�0
predict the parameters without actually firing the
ammunition. And once the simulation confirms the
achievement of desired parameters a trial firing
may be conducted to validate the simulation.
internal Ballistics :
The firing sequence of a gun commences with the
ignition of primer of the cartridge either electrically
or by percussion. The hot gases generated by
ignition of the primer in turn initiates combustion
of propellant. At this stage the gun chamber is
virtually sealed by the projectile. So, the gases and
the energy liberated by the primer and propellant
get confined to a limited volume. Thus, resulting
in rapid increase in pressure and the temperature
within the chamber. The burning rate of propellant
is proportional to the chamber pressure. Therefore,
increase in chamber pressure leads to further
increase in the rate of gas generation. This process
would continue until the gun gets exploded.
This doesn’t, however, happen practically as the
projectile (which is crimped to the cartridge case)
starts moving along the barrel as soon as the
chamber pressure reaches a threshold level known
as shot-start pressure(as shown in graph).
With the projectile moving ahead
the volume to be filled in by the high pressure
propellant gasses also increases. At this point the
propellant is still burning and increase in volume
is much lesser compared to generation of high
pressure propellant gas. Therefore, the resultant
pressure keeps on increasing until the space
being created behind the accelerating projectile
exceeds the rate at which high pressure gas is
being produced. Thereafter, (after reaching the
maximum pressure) the pressure begins to fall.
The next stage is the all-burnt position
where the burning of propellant is completed.
Still, there remains a considerable amount of
pressure in the gun for the remaining motion
of the projectile along the bore. Therefore, the
projectile continues to accelerate even after the
all-burnt position. The moment the projectile
leaves the gun, the chamber pressure reduces to
about one sixth of the peak pressure.
Eg is the kinetic energy of the propellant gas
motion,
Eu is the kinetic energy of the unburnt
propellant motion,
Er is the kinetic energy due to recoil of the
gun,
Eb is the heat energy lost to the barrel,
Eh is the residual heat energy in the propellant
gasses,
Es is the strain energy used in expanding the
barrel,
Ef is the energy lost in engraving the driving
band and the overcoming friction in the
bore.
intermeDiate Ballistics :
As the projectile moves down the gun barrel, it
compresses the air ahead of it. The gun barrel acts
like a shock tube in which a near-planar shock
forms. When this shock exits the muzzle, it forms
a spherical shock wave . As the projectile moves
faster and faster in the barrel a second precursor
will be formed. This precursor moves faster than the
first one. The under-oxidised propellant gas reacts
with oxygen present in the precursor flow field
which gives rise to pre-flash. Several microseconds
after the precursor shock appears but before the
projectile exit a bottle shaped structure known as
bottle shock and an annular vortex is formed. All
these phenomena ultimately result in a bulge of
propellant gases through the precursor shock both
preceding and following the projectile.
eXterior Ballistics :
Once the projectile is out of the influence
of the propellant gases the flight of the
projectile is affected by the factors associated
with the atmosphere and the projectile itself.
The properties of atmosphere relevant to
the projectile flight trajectory are air density,
temperature, static pressure, viscosity and wind
speed direction. The projectile characteristics
which have some bearing on its flight trajectory
are its mass, caliber, shape and axial spin rate.
If the projectile happens to move in vacuum
the only force acting on a projectile in flight
is that due to gravitational acceleration. But in
air, there will be an additional force opposing
the forward motion of the projectile due to the
air resistance known as ‘drag’. The drag force
has three prime components which modify the
trajectory and these are : -
(a) Skin friction
(b) Pressure drag
(c) Yaw-dependent drag
methoDoloGy :
Computer models may be developed for internal,
intermediate and external ballistics for the
existing guns of caliber starting from 30mm to
�00mm. Thermophysics i.e. the quantification of
changes in a substance’s energy state caused by
changes in the physical state of the material and
Thermochemistry i.e. the quantification of changes
in a substance’s energy state caused by changes
in the chemical composition of the material’s
molecules and Thermodynamics i.e. the study
of energy transformations are to be taken into
account in detail while developing the model for
internal ballistics. Computational Fluid Dynamics
will be utilized to model the Intermediate ballistics.
There are two opposing forces acting
on a projectile within the gun barrel, namely
the propelling force due to the high pressure
propellant gas pushing the base of the projectile
and the frictional force between the projectile
and the bore (including the high resistance
due to engraving of Driving Band in the barrel
bore) opposing the motion of the projectile.
Additionally, the reaction between the projectile
and the rifling of a rifled gun translates a small
part of the propelling force into a torque which
causes the projectile to rotate. Any physical
system has to obey the principle of conservation
of energy. So, the total energy liberated in the
form of propellant gasses at high temperature,
which gets converted into other forms remains
the same. Therefore it may be written that : -
Et = E
p+E
g+E
u+E
r+E
b+E
n+E
s+E
f
Where Ep is the kinetic energy due to the
projectile motion,
66 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
The models developed for internal and
intermediate ballistics will provide the Muzzle
velocity of the projectile. For External Ballistics
the Six-Degrees-of-Freedom (6-DOF) trajectory
models may be exploited. Experimentation with
wind tunnels is required to be carried out to
determine aerodynamic co-efficient of projectile.
Muzzle velocity obtained from internal and
intermediate ballistic model and aerodynamic co-
efficient determined with the help of wind tunnel
experimentation will be fed to 6-DOF trajectory
model to predict the projectile trajectory.
Computer Programming language C, C++,
MATLAB and Ballistic software
package PRODAS are the available options for
computation.
These models will be validated by
comparing the outputs of the models with the
practical data generated during the actual firings
of the guns. Once validated these models will be
utilized for guns/projectiles being developed/for
future development.
conclUsion :
The sequence of operations during firing
i.e. starting from the primer initiation until the exit
of projectile from the muzzle (Internal ballistics),
motion of the projectile in the close vicinity of the
gun muzzle (Intermediate ballistics) and the flight
trajectory of projectile in air (external ballistics) can
be modeled using advanced computing facilities
with a view to predicting the projectile trajectory
and the fall of shot. In the earlier days this was
being done by mathematical analysis. However,
the mathematical functions being continuous
in nature are not appropriate to model Internal
ballistics, which is a discontinuous process.
On the contrary computer model will
have many advantages over analytical models.
It will have the capability to include realistic
data and functions, which can effectively model
discontinuous processes like ignition of primer
and propellant and engraving of Driving band.
Computer models are much more flexible in the
sense that various parameters of the projectile
propellant or the gun can be changed frequently
to arrive at the optimum combination. Further,
with the availability of advanced high speed
computing facilities it is possible to predict
the flight trajectory of gun projectile, which is
the ultimate measure of the gun performance.
Therefore, it is indeed worth experimenting the
gun systems design with the help of computer
simulations, which has the capability to predict
the gun performance without firing a shot.
references :
[�] G.M. Moss,D.W. Leeming and C Farrar : Military Ballistics
[2] Text book of Gunnery prepared by the Ordnance College, Woolwich, UK
[3] DE Carlucci and SS Jacobson : Theory and Design of Guns and Ammunition
[�] Robert L McCoy : Modern Exterior Ballistics [5] J Sahu, KR Heavey and R Buretta : CFD Modelling of
a Course Corrected Artillery Projectile at Transonic Speeds
[6] H Jung, U Hwang and J kim : Aerodynamic and Ballistic Analysis of Rifled Mortar Munition
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 67
Proceedings of the National Seminar : 23 Nov 20�0
MORPHOLOGICAL AND ELECTRICAL PROPERTIES OF POLY(M-TOLUIDINE)/MODIFIED MWCNT CONDUCTING POLYMER COMPOSITES.
Matru Prasad Dash�, G.C. Mohanty2 & P.L.Nayak�
�.P.L.Nayak Research Foundation, Neelachal Bhavan, Cuttack- 75300�, India
2.Dept. of Physics Ravenshaw University,Cuttack-753003, India
Corresponding Author : Prof. P.L.Nayak
Email : plnayak @rediffmail.com
Abstract
We describe here the synthesis of hydrochloric acid (HCl) doped poly(m-toluidine)
(PMT) with carboxylic groups containing multi-walled carbon nanotubes (c-MWCNTs)
via in situ polymerization. m-Toluidine monomers were adsorbed on the surface of
MWCNTs and polymerized to form PMT/c-MWCNT composites. The composites were
characterized by using FTIR, SEM, TEM and XRD analysis. Scanning electron microscopy
(SEM) and transmission electron microscopy (TEM) images showed that both the thinner
fibrous phase and the larger block phase could be observed. The individual fibrous
phases had diameters about 100 nm, and therefore must be the carbon nanotubes
(diameter 20–30 nm) coated by a PMT layer. The electrical conductivities of PMT/c-
MWCNT composites were improved relative to those of PMT without c-MWCNTs.
Keywords: MultiwalledCarbonnanotube(MWCNT), poly(m-toluidine); polymerization; conducting
polymer
1.introduction
Carbon nanotubes (CNTs) including
multi-walled and single-walled carbon nanotubes
(MWCNTs and SWCNTs, respectively) with
exceptional structural, mechanical and electronic
properties [�, 2] have received considerable interest
in fabricating advanced functional materials [3, �].
Currently, much attention is paid to the formation
of CNTs/conducting polymer composites which
are considered as a promising approach to exploit
synergetic effects arising from the components
and show potential for many electronic devices
such as PEDOT/CNTs in organic light emitting
diodes, PPV/CNTs in photovoltaic cells, PPy/ CNTs
in battery and PANI/CNTs in supercapacitors [5–7].
Among various conducting polymers, PANI is a
promising candidate for practical applications due
Contributed Paper
6� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
to its good processibility, environmental stability
and reversible control of electrical properties by
both charge-transfer doping and protonation [�].
However, the major disadvantage of PANI/CNT is
its insolubility in common organic solvents and its
infusibility. Preparation of alkyl group substituted
PANI/CNT is a method to obtain soluble PANI/
CNT composites. Soluble methyl-substituted
PANI called poly (m-toluidine) (PMT) have been
synthesized by electrochemical and chemical
method. Recently, PMT was also found to have
additional advantage with respect to PANI due
to its faster switching time between the oxidized
and the reduced states .Fig. � outlines the four
different oxidation states of PMT.
In the present communication, we wish to
describe the synthesis and characterization of PMT
with MWCNT fabricated by in situ polymerization
.The nanocomposites were characterized by
a number of techniques including scanning
electron microscopy (SEM), transmission electron
microscopy (TEM), and electrical conductivity.
2.Work-up procedure.
2.1 Materials.
m-Toulidine was purchased from Aldrich,
Multi-walled CNT (<90% purification) used in this
study was purchased from Cheap Tubes (USA, �0–
20 nm diameter). Other reagents like ammonium
persulfate (APS), hydrochloric, sulfuric, and nitric
acid (Sigma Chemicals) were of analytical grade.
2.2 Oxidation of MWCNT:
MWCNTs (0.30 g) were suspended in 20
ml of a 3:� (v) mixture of concentrated H2SO
� (9�
wt%)/HNO3 (60 wt%). The above mixture was
sonicated in a water bath for 2 h, and stirred for
�5 h at 350C. Then the mixture was diluted with
�00 ml of distilled water, vacuum-filtered and
washed with distilled water until pH of the filtrate
was 7.0. The filtered solid was dried under vacuum
for 20 h at 600C, obtaining carboxyl-functionalized
MWCNTs (MWCNT-COOH) (0.2� g).
2.3 Synthesis of PMT/c-MWCNT polymer
composites.
PMT/c-MWCNT composites were
synthesized by in situ chemical oxidative
polymerization. In a typical composite
synthesis experiment, various weight ratio
of c-MWCNTs were dissolved in �0mL �M
hydrochloric acid solutions and ultrasonicated
over 2 h, then transferred into a 250mL beaker.
0.�2� g m-toluidine monomer was added to
the above c-MWCNTs suspension. Then a 20ml
�M hydrochloric acid solution containing 0.9�2
g ammonium persulfate (APS) was added into
the suspension with constant mechanical
stirring at room temperature. The reaction
mixture was stirred for a further �2 h, and then
Fig. 1. Four different redox forms of PMT: (a) leucoemeraldine base (fully reduced form), (b) emeraldine base (halfoxidized form), (c) conducting emeraldine salt (half-oxidized and protonated form), and (d) pernigraniline base (fully oxidized form).
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 69
Proceedings of the National Seminar : 23 Nov 20�0
filtered. The remaining filter cake was rinsed
several times with distilled water and ethanol.
The power thus obtained was dried under
vacuum at 600C for 2� h. The % of c-MWCNT
were used 0, 2, 5%.
3. measurements.
3.1Morphology
Morphology of the PMT/c-MWCNT
composite was investigated using a Philip XL 30
SEM at an accelerating voltage of 25 kV. The sample
was fractured at liquid nitrogen temperature and
then was coated with a thin layer of gold before
observation.
3.2 TEM
TEM experiments were performed on
a Hitachi H-��00 electron microscope with an
acceleration voltage of 200 kV.
3.3 Conductivity.
The standard Van Der Pauw DC four-
probe method was used to measure the
electron transport behaviors of PMT and PMT/
c-MWCNT composites. The samples of PMT and
PMT/c-MWCNTs were pressed into pellet. The
pellet was cut into a square. The square was
placed on the four probe apparatus, providing
a voltage for the corresponding electrical
current could be obtained. The electrical
conductivity of samples was calculated by the
following formula: σ (S/cm) = (2.�� ×�0/S) ×
(I/E), where σ is the conductivity, S the sample
side area, I the current passed through outer
probes, and E the voltage drop across inner
probes.
4. results and discussion.
Fig 2. SEM images of; a.. c-MWCNT; b.PMT/c-MWCNT (2%); c.PMT/c-MWCNT (5%)
4.1. SEM
The SEM pictures of the pristine c-
MWCNTs, and nanocomposite with 2, and 5, % of c-
MWCNTs are presented in Fig.2. Figure 2a shows the
disentanglement of the c-MWCNTs, and the slight
reduction in the length of the nanotube is observed
after oxidation with 3:� concentrated H2SO� and
HNO3 mixture. In the case of nanocomposites (Fig.
2b,2c), a tubular layer of coated copolymer film is
clearly present on the surface of c-MWCNTs, and
the diameter of the nanocomposite is increased
substantially as compared to that of the c-MWCNTs,
depending on the copolymer content. From this
70 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
observation, it can be attributed that the coating
of copolymer takes place only at the outer surface
of the c-MWCNTs. The formation of the copolymer-
coated tubular nanocomposite is believed to
arise from the strong interaction between the
co-monomer and c-MWCNTs. This interaction is
thought to be made up of two components: one is
the π–π electron interaction between the MWCNTs
and the comonomer [9] and the other is the
hydrogen bond interaction between the carboxyl
group of the c-MWCNTs and amino group of the
co-monomers. Such a strong interaction ensures
that the co-monomer molecules are adsorbed on
the surface of the c-MWCNTs. The polymerization
of co-monomer inside the c-MWCNTs is hindered
by the restricted access of the reactants to the
interior of the c-MWCNTs because of the presence
of the carboxyl group at the meta position of the
co-monomer. This is in agreement with the findings
reported in the literature [�0].
4.2.TEM:
The TEM spectra of the c-MWCNT and
PMT with 5% c-MWCNT are presented in Figure3.
The uniform deposition of PMT on the c-MWCNT
is similarly demonstrated by transmission electron
microscopy (TEM), which shows the bilayered
structure of coated C-MWCNT. As the internal
cavity is well discernible, we conclude that the
coating with PMT takes place only at the outer
surface of thec-MWCNT. The polymerization of
PMT inside the c-MWCNT is hindered by the
restricted access of reactants to the interior
of the c-MWCNT. The comonomer molecules
are uniformly polymerized on the surface of c-
MWCNTs and form a tubular nanocomposite. The
diameter of the nanocomposite becomes larger
than that of the c-MWCNTs after polymerization.
4.3 Conductivity:
Fig3. TEM image of a.MWCNT.b.PMT/c-MWCNT (5%)
Fig. 4. Conductivity versus the weight percent of c-MWCNT/PMTcomposites
The electrical conductivities PMT and
PMT/c- MWCNT composites are measured using
the standard Van Der Pauw DC four-probe method
and shown in Figure �. The conductivity of MWCNT
is about 0.2 S/cm. The conductivities of PMT
synthesized in the presence of hydrochloric acid
shows a room temperature conductivity of 2.�×�0−�
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 7�
Proceedings of the National Seminar : 23 Nov 20�0
S/cm . The lower room temperature conductivity
of PMT than PANI probably has something to do
with its substituted group and low protonic acid
doping degree. Meanwhile, the addition of 2 wt.%
c-MWCNT into PMT, the conductivity at room
temperature increases from 2.� to 7×�0−� S/cm. With
the continuous increase in the content of c-MWCNT,
the conductivity at room temperature gradually
increases from 7×�0−� S/cm for 2 wt.% MWCNT-
containing PMT/c-MWCNT composites to 9×�0−�S/
cm for 5 wt.% MWCNT containing PMT/c-MWCNT
composites. The conductivities of PMT/c-MWCNT
composites with 5 wt.% c-MWCNTs content at room
temperature are much more higher than those of
PMT without c-MWCNTs. The reason is probably that
c-MWCNTs serve as a “conducting bridge” between
the PMT conducting domains, which increases the
effective percolation.
5. Conclusion
PMT/c-MWCNTs nanocomposites were
successfully synthesized via in situ polymerization
method. SEM and TEM measurement ascertained
that the c-MWCNTs were homogeneously
dispersed in the copolymer matrix. Room
temperature conductivity of nanocomposite
increased several times as increasing of percentage
of c-MWCNT .In addition, the versatility of this
method could be extended to prepare other
polymer/ CNT nanocomposites by choosing
appropriate experimental conditions
Acknowledgments:
The authors are thankful to Dr.S.Sasmal, Principal
Scientist, CRRI, Cuttack for encouragements and
Dr. Munesh Chandra Adhikary for suggestions.
6. references:
[�] Iijima S., Ichihashi T: Single-shell carbon nanotubes of �-nm diameter.Nature, 363, 603-605 (�993).
[2] Iijima S: Helical microtubules of graphitic carbonNature ,35�, 56-5� (�99�).
[3] Ajayan P.M., Stephan O., Colliex C., Trauth D:Aligned Carbon Nanotube Arrays Formed by Cutting a Polymer Resin—Nanotube Composite Science, 265, �2�2-�2�� (�99�).
[�] Wong E.W., Sheehan P.E., Lieber C.M.:Nanobeam Mechanics: Elasticity, Strength and Toughness of Nanorods and Nanotubes ,Science ,277, �97�-�975 (�997).
[5] Woo H.S., Czerw R., Webster S., Carroll D.L: Organic light emitting diodes fabricated with single wall carbon nanotubes dispersed in a hole conducting buffer: the role of carbon nanotubes in a hole conducting polymer,Synth. Met. ��6, 369-372 (200�).
[6] Ago H., Petritsch K., Shaffer M.S.P., Windle A.H., Friend R.H., Composites of Carbon Nanotubes and Conjugated Polymers for Photovoltaic Devices, Adv. Mater. ��, �2��-�2�5, (�999).
[7] Sivakkumar S.R., Kima W.J.,. Choi J.A, MacFarlane D.R., Forsyth M., Kima D.W:Electrochemical performance of polyaniline nanofibres and polyaniline/multi-walled carbon nanotube composite as an electrode material for aqueous redox supercapacitors, J. Power Sources ,�7�, �062 (2007).
[�] Premamoy G., Samir K.S., Amit C:Characterization of poly(vinyl pyrrolidone) modified polyaniline prepared in stable aqueous medium,Eur. Polym. J, 35,699-7�0(�999).
[9] A Star, JF Stoddart, D Steuerman, M Diehl, A Bouaki, EW Wong, X Yang, SW Chung, H Choi, JR Heath Angew Chem Int Ed ,�0,�72�(200�).
[�0] Deng M., Yang B., Hu Y:Polyaniline deposition to enhance the specific capacitance of carbon nanotubes for supercapacitors, J Mater Sci ,�0,502�-5023(2005)
72 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
ABSTRACT
In the present study, we report modification of pulsed laser deposited c-axis oriented thin films
of YBa2Cu
3O
7-y (YBCO) by secondary electrons emitted radially in a cylindrical region around the
path of swift heavy ions. Our in situ temperature dependent resistivity measurement and in situ
low temperature x-ray diffraction (XRD) study on YBCO irradiated at liquid N2 temperature with
200 MeV Ag ions showed that these secondary electrons selectively create point defects at CuO
basal chains of YBCO. These low energy secondary electrons create defects by inelastic interaction
process. These defects frozen by low temperature irradiation lead to decrease of Tc and integrated
XRD intensity of (00l) peak at low fluences, where ion induced amorphous latent tracks are far
apart from each other. Beyond a critical fluence (1012 ions cm-2), the radially strained region around
the amorphous latent tracks tend to overlap and a two step superconducting transition evolves
instead of a single transition.
A REPORT ON LOW TEMPERATURE IRRADIATION STUDY IN YBa2Cu
3O
7-y
SUPERCONDUCTOR
R. Biswal and N.C. Mishra
Department of Physics, Utkal University, Bhubaneswar 75�00�
Email:[email protected], [email protected]
Keywords: Swift heavy ion irradiation, cuprate superconductor, secondary electrons,
introDUction
The discovery of superconductivity has been
recognized as one of the greatest scientific
achievements of twentieth century. The materials,
which obeyed this phenomenon was called as the
superconductor. It is basically a state of matter
below certain temperature where the dc resistivity
suddenly drops to zero. This temperature is known
as superconducting transition temperature (Tc)
and is defined for every specific material. In �9��,
Heike Kamerlingh-Onnes and his assistant Gilles
Holst were discovered the superconductivity
phenomenon in mercury at very low temperature
in their Leiden laboratory in �9�� [�]. The
mechanism of superconductivity was proposed
by J. Bardeen, L. Cooper and R. Schrieffer long �6
years after its discovery, in �957 for which they
were jointly awarded the Noble prize. Another
breakthrough came in �9�6 with Bednorz and
Muller discovering superconductivity in ceramic
matter, which is normally a good insulator. This
opened up a new branch of superconductivity,
now known as the high Tc superconductivity
(HTSC). One year after, the discovery of a new rare
earth based copper oxide superconductor,
YBa2Cu
3O
7-y [2], which was the first material having
a transition temperature Tc higher than the
boiling point of liquid nitrogen, took the world by
storm. The mechanism has remained an enigma.
People worked in its different aspects at an
unprecedented pace, because of the technological
prospects, this enigmatic phenomenon of lossless
electric energy transmission coupled with
complete diamagnetic properties, tunneling
etc it promised. Understanding the still elusive
mechanism of superconductivity in these high
Tc superconducting systems and exploring their
application possibilities have involved modifying
the properties of these systems by varieties of
methods. At the microscopic scale, these methods
include doping at different lattice sites of the
complex planner structure of HTSC systems and
irradiation by ion beams. Here, a short summary and
discourse on the modification of YBa2Cu
3O
7-y (YBCO)
thin films by swift heavy ion (SHI) irradiation
induced secondary electrons at low temperature
is presented.
At high energies, heavy ions dissipate
energy mostly to the electrons along the trajectory
in the target medium. The excited electrons
confined to the ion path transfer their energy to
lattice in a very short period and the consequent
modifications are the amorphous latent track
creation along the ion trajectory when the
electronic energy loss, Se exceeds a threshold value,
i.e., Se>S
eth [3], creation of defects [�], annealing of
the pre-existing defects [5], changes of phases
around the ion path [6], and also a macroscopic flow
of matter [7] in amorphous materials. However, a
fraction of highly excited electrons may leave the
ion path and enter into the surrounding pristine
materials which are called as secondary electrons
(SE). A few secondary electrons may also come
out from the target material if these have enough
energy [�]. The trapped SEs are, being of very
low energy, not known to create lattice disorder
elastically however these electrons can cause
photo-luminescence emission in alkali halides.
The question we address here; can the secondary
electrons trapped in the materials medium
create defect by any other means, if not by elastic
scattering. In YBCO thin films, we show that these
SE can indeed create defects by inelastic electron
capture process as in dissociative recombination
observed in organic and polymeric materials.
It is widely known that the
superconducting and normal state properties
of YBCO, an extensively studied high Tc
superconductor, are strongly influenced by
disorder in the CuO chains [9,�0]. Chains are not
continuous but broken into segments of finite
length due to presence of the vacant oxygen sites.
Oxygen disorders in the form of vacancy in the
chains reduce the average chain length with a
direct influence on the hole (carrier) concentration
and hence the Tc. Shorter chains yield reduced
carrier densities, while chain merging results
in increased carrier concentrations [9]. Oxygen
disorder in CuO chain of YBCO has been achieved
by quenching of samples from high temperatures
to liquid nitrogen temperature and the Tc increase
observed in room temperature annealed bulk
samples has been interpreted in terms of an
increase in the carrier density resulting from chain
ordering [�0]. At high temperatures, not only the
Contributed Paper
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 73
Proceedings of the National Seminar : 23 Nov 20�0
ABSTRACT
In the present study, we report modification of pulsed laser deposited c-axis oriented thin films
of YBa2Cu
3O
7-y (YBCO) by secondary electrons emitted radially in a cylindrical region around the
path of swift heavy ions. Our in situ temperature dependent resistivity measurement and in situ
low temperature x-ray diffraction (XRD) study on YBCO irradiated at liquid N2 temperature with
200 MeV Ag ions showed that these secondary electrons selectively create point defects at CuO
basal chains of YBCO. These low energy secondary electrons create defects by inelastic interaction
process. These defects frozen by low temperature irradiation lead to decrease of Tc and integrated
XRD intensity of (00l) peak at low fluences, where ion induced amorphous latent tracks are far
apart from each other. Beyond a critical fluence (1012 ions cm-2), the radially strained region around
the amorphous latent tracks tend to overlap and a two step superconducting transition evolves
instead of a single transition.
A REPORT ON LOW TEMPERATURE IRRADIATION STUDY IN YBa2Cu
3O
7-y
SUPERCONDUCTOR
R. Biswal and N.C. Mishra
Department of Physics, Utkal University, Bhubaneswar 75�00�
Email:[email protected], [email protected]
Keywords: Swift heavy ion irradiation, cuprate superconductor, secondary electrons,
introDUction
The discovery of superconductivity has been
recognized as one of the greatest scientific
achievements of twentieth century. The materials,
which obeyed this phenomenon was called as the
superconductor. It is basically a state of matter
below certain temperature where the dc resistivity
suddenly drops to zero. This temperature is known
as superconducting transition temperature (Tc)
and is defined for every specific material. In �9��,
Heike Kamerlingh-Onnes and his assistant Gilles
Holst were discovered the superconductivity
phenomenon in mercury at very low temperature
in their Leiden laboratory in �9�� [�]. The
mechanism of superconductivity was proposed
by J. Bardeen, L. Cooper and R. Schrieffer long �6
years after its discovery, in �957 for which they
were jointly awarded the Noble prize. Another
breakthrough came in �9�6 with Bednorz and
Muller discovering superconductivity in ceramic
matter, which is normally a good insulator. This
opened up a new branch of superconductivity,
now known as the high Tc superconductivity
(HTSC). One year after, the discovery of a new rare
earth based copper oxide superconductor,
YBa2Cu
3O
7-y [2], which was the first material having
a transition temperature Tc higher than the
boiling point of liquid nitrogen, took the world by
storm. The mechanism has remained an enigma.
People worked in its different aspects at an
unprecedented pace, because of the technological
prospects, this enigmatic phenomenon of lossless
electric energy transmission coupled with
complete diamagnetic properties, tunneling
etc it promised. Understanding the still elusive
mechanism of superconductivity in these high
Tc superconducting systems and exploring their
application possibilities have involved modifying
the properties of these systems by varieties of
methods. At the microscopic scale, these methods
include doping at different lattice sites of the
complex planner structure of HTSC systems and
irradiation by ion beams. Here, a short summary and
discourse on the modification of YBa2Cu
3O
7-y (YBCO)
thin films by swift heavy ion (SHI) irradiation
induced secondary electrons at low temperature
is presented.
At high energies, heavy ions dissipate
energy mostly to the electrons along the trajectory
in the target medium. The excited electrons
confined to the ion path transfer their energy to
lattice in a very short period and the consequent
modifications are the amorphous latent track
creation along the ion trajectory when the
electronic energy loss, Se exceeds a threshold value,
i.e., Se>S
eth [3], creation of defects [�], annealing of
the pre-existing defects [5], changes of phases
around the ion path [6], and also a macroscopic flow
of matter [7] in amorphous materials. However, a
fraction of highly excited electrons may leave the
ion path and enter into the surrounding pristine
materials which are called as secondary electrons
(SE). A few secondary electrons may also come
out from the target material if these have enough
energy [�]. The trapped SEs are, being of very
low energy, not known to create lattice disorder
elastically however these electrons can cause
photo-luminescence emission in alkali halides.
The question we address here; can the secondary
electrons trapped in the materials medium
create defect by any other means, if not by elastic
scattering. In YBCO thin films, we show that these
SE can indeed create defects by inelastic electron
capture process as in dissociative recombination
observed in organic and polymeric materials.
It is widely known that the
superconducting and normal state properties
of YBCO, an extensively studied high Tc
superconductor, are strongly influenced by
disorder in the CuO chains [9,�0]. Chains are not
continuous but broken into segments of finite
length due to presence of the vacant oxygen sites.
Oxygen disorders in the form of vacancy in the
chains reduce the average chain length with a
direct influence on the hole (carrier) concentration
and hence the Tc. Shorter chains yield reduced
carrier densities, while chain merging results
in increased carrier concentrations [9]. Oxygen
disorder in CuO chain of YBCO has been achieved
by quenching of samples from high temperatures
to liquid nitrogen temperature and the Tc increase
observed in room temperature annealed bulk
samples has been interpreted in terms of an
increase in the carrier density resulting from chain
ordering [�0]. At high temperatures, not only the
Contributed Paper
7� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
oxygen in the CuO chains are disordered, but also
the oxygen content is reduced below the optimal
value for highest Tc. Thus subsequent annealing
of quenched samples at RT had led to evolution
of ortho-II structure and increase of Tc to ~ 60 K
corresponding to this structure.
We however show that low energy
secondary electrons can create oxygen defects
inelastically in YBCO matrix with optimal oxygen
content. These secondary electrons primarily
dislodge oxygen atoms selectively from the CuO
chains, since this is the lightest and more loosely
bound species of the structure.
material anD methoDs
In situ temperature dependent resistivity, ρ(T) below
�30 K and in situ low temperature x-ray diffraction
(XRD) measurements have been undertaken to
study the evolution of the defect structure by SHI
irradiation induced secondary electrons in YBCO
matrix where the defects sensitively influence the
superconducting characteristics and the crystal
structure. Sintered YBCO target was prepared by
conventional solid-state reaction route. Thin films
of YBCO were deposited from this sintered bulk
target by pulsed laser deposition technique on
single crystal LaAlO3 substrate [��]. The films of
�50 nm thick were irradiated with 200 MeV �07Ag
ions using the �5 UD tandem pelletron accelerator
at the IUAC, New Delhi.
The electronic energy loss, Se, nuclear
energy loss, Sn, and range of the 200 MeV Ag ions
in YBCO calculated from SRIM 2006 are 25.�� keV
nm-�, 70.95 eV nm-� and �2.66 µm respectively.
Since the thickness of the sample is much less than
the range of the ion beams, the ions are implanted
much deeper in the substrate. Also the Se is almost
same throughout the film thickness implying the
uniform energy deposition in the sample and
mostly due to Se. Since the S
e of 200 MeV Ag ions
in YBCO exceeds its threshold value, Seth
(~ 20 keV
nm-�) [�2], these ions create amorphized latent
tracks along their trajectory in the films.
The irradiation fluence, Φ was varied
from ��09 ions cm-2 to 2 �0�3 ions cm-2. In situ
temperature dependent resistivity, ρ(T) was
measured after irradiating the sample at �2 K with
ion beams at different fluences. The ρ(T) data
were taken right after irradiation in heating cycle
up to a maximum temperature of �30 K. In these
measurements, the sample temperature was thus
kept well below room temperature (RT) to avoid
annealing of irradiation-induced defects. The details
of the experiment is discussed in reference [��].
A Brucker X-ray diffractometer (Model
D�) installed in the beam line was used to collect
XRD data in situ using Cu Kα radiation after each
fluence of irradiation at �9 K [�3]. Here also the
sample temperature was kept well below RT to
freeze the irradiation induced defects.
resUlts anD DiscUssion
In situ temperature dependent resistivity study The
variation of resistivity as a function of temperature,
ρ(T) of a YBCO thin film at different ion fluences
are shown in figures � and 2. Depending upon the
nature of resistivity variation with temperature,
three different fluence regimes are identified. The
low fluence regime corresponds to the fluence
φ ≤ �.7� × �0�� ions cm-2, where a single step
superconducting transition is observed and the
Tc and T
c0, extracted from the ρ(T) data, follow a
decreasing trend with irradiation fluence (Inset of
figure �).
Increasing fluence beyond �.7��0�� ions.cm-2,
though the two-step superconducting transition
could be seen up to a fluence of 6.�7�0�2 ions
cm-2, the zero resistive state could not be achieved
above at the lowest irradiation temperature (�2 K)
(Figure 2). Increasing fluence in the mid-fluence
regime (6.7�×�0�� ions cm-2 ≤ Φ ≤ 6.�7×�0�2 ions
cm-2) causes only a slight decrease of Tc within 0.�
K (Inset (b) of figure 2). At the highest fluence of
�.��0�3 ions cm-2, superconductivity is completely
destroyed and ρ(T) showed a semiconducting
behavior and is termed as high flurnce regime
(Inset (a) of figure 2).
Irradiation at very low fluences and
at low temperatures has enabled us to look
into subtle features like the irradiation induced
metastable defect states, which anneal out at
higher temperature. We probe into the effect of
these metastable defects on the superconducting
transition of YBCO in the presence of a very few
number of stable amorphized latent tracks. While
literature reports the rate of Tc suppression is small
at low fluences and large at high fluences in YBCO
thin films irradiated at room temperature [��,�5].
On the contrary we find at very low fluences, the
rate of Tc suppression is two orders of magnitude
higher than that at high fluences. Defect recovery
due to annealing was studied in a few samples
by monitoring their ρ(T) behaviour immediately
after ion irradiation at low temperature and
after annealing the sample at 297 K for � hour.
The tendency of the superconducting transition
temperature and normal state resistivity to recover
to their pre-irradiation values indicates irradiation
induced defects are basically point defects which
anneal out at 297 K.
Figure �. Evolution of superconducting transition with irradiation at low fluences as probed through
resistivity vs. temperature measurement for thin film of YBa2Cu
3O
7-δ irradiated at �2 K by 200 MeV Ag
ions. The inset shows the Tc and T
c0 variation in this fluence range.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 75
Proceedings of the National Seminar : 23 Nov 20�0
oxygen in the CuO chains are disordered, but also
the oxygen content is reduced below the optimal
value for highest Tc. Thus subsequent annealing
of quenched samples at RT had led to evolution
of ortho-II structure and increase of Tc to ~ 60 K
corresponding to this structure.
We however show that low energy
secondary electrons can create oxygen defects
inelastically in YBCO matrix with optimal oxygen
content. These secondary electrons primarily
dislodge oxygen atoms selectively from the CuO
chains, since this is the lightest and more loosely
bound species of the structure.
material anD methoDs
In situ temperature dependent resistivity, ρ(T) below
�30 K and in situ low temperature x-ray diffraction
(XRD) measurements have been undertaken to
study the evolution of the defect structure by SHI
irradiation induced secondary electrons in YBCO
matrix where the defects sensitively influence the
superconducting characteristics and the crystal
structure. Sintered YBCO target was prepared by
conventional solid-state reaction route. Thin films
of YBCO were deposited from this sintered bulk
target by pulsed laser deposition technique on
single crystal LaAlO3 substrate [��]. The films of
�50 nm thick were irradiated with 200 MeV �07Ag
ions using the �5 UD tandem pelletron accelerator
at the IUAC, New Delhi.
The electronic energy loss, Se, nuclear
energy loss, Sn, and range of the 200 MeV Ag ions
in YBCO calculated from SRIM 2006 are 25.�� keV
nm-�, 70.95 eV nm-� and �2.66 µm respectively.
Since the thickness of the sample is much less than
the range of the ion beams, the ions are implanted
much deeper in the substrate. Also the Se is almost
same throughout the film thickness implying the
uniform energy deposition in the sample and
mostly due to Se. Since the S
e of 200 MeV Ag ions
in YBCO exceeds its threshold value, Seth
(~ 20 keV
nm-�) [�2], these ions create amorphized latent
tracks along their trajectory in the films.
The irradiation fluence, Φ was varied
from ��09 ions cm-2 to 2 �0�3 ions cm-2. In situ
temperature dependent resistivity, ρ(T) was
measured after irradiating the sample at �2 K with
ion beams at different fluences. The ρ(T) data
were taken right after irradiation in heating cycle
up to a maximum temperature of �30 K. In these
measurements, the sample temperature was thus
kept well below room temperature (RT) to avoid
annealing of irradiation-induced defects. The details
of the experiment is discussed in reference [��].
A Brucker X-ray diffractometer (Model
D�) installed in the beam line was used to collect
XRD data in situ using Cu Kα radiation after each
fluence of irradiation at �9 K [�3]. Here also the
sample temperature was kept well below RT to
freeze the irradiation induced defects.
resUlts anD DiscUssion
In situ temperature dependent resistivity study The
variation of resistivity as a function of temperature,
ρ(T) of a YBCO thin film at different ion fluences
are shown in figures � and 2. Depending upon the
nature of resistivity variation with temperature,
three different fluence regimes are identified. The
low fluence regime corresponds to the fluence
φ ≤ �.7� × �0�� ions cm-2, where a single step
superconducting transition is observed and the
Tc and T
c0, extracted from the ρ(T) data, follow a
decreasing trend with irradiation fluence (Inset of
figure �).
Increasing fluence beyond �.7��0�� ions.cm-2,
though the two-step superconducting transition
could be seen up to a fluence of 6.�7�0�2 ions
cm-2, the zero resistive state could not be achieved
above at the lowest irradiation temperature (�2 K)
(Figure 2). Increasing fluence in the mid-fluence
regime (6.7�×�0�� ions cm-2 ≤ Φ ≤ 6.�7×�0�2 ions
cm-2) causes only a slight decrease of Tc within 0.�
K (Inset (b) of figure 2). At the highest fluence of
�.��0�3 ions cm-2, superconductivity is completely
destroyed and ρ(T) showed a semiconducting
behavior and is termed as high flurnce regime
(Inset (a) of figure 2).
Irradiation at very low fluences and
at low temperatures has enabled us to look
into subtle features like the irradiation induced
metastable defect states, which anneal out at
higher temperature. We probe into the effect of
these metastable defects on the superconducting
transition of YBCO in the presence of a very few
number of stable amorphized latent tracks. While
literature reports the rate of Tc suppression is small
at low fluences and large at high fluences in YBCO
thin films irradiated at room temperature [��,�5].
On the contrary we find at very low fluences, the
rate of Tc suppression is two orders of magnitude
higher than that at high fluences. Defect recovery
due to annealing was studied in a few samples
by monitoring their ρ(T) behaviour immediately
after ion irradiation at low temperature and
after annealing the sample at 297 K for � hour.
The tendency of the superconducting transition
temperature and normal state resistivity to recover
to their pre-irradiation values indicates irradiation
induced defects are basically point defects which
anneal out at 297 K.
Figure �. Evolution of superconducting transition with irradiation at low fluences as probed through
resistivity vs. temperature measurement for thin film of YBa2Cu
3O
7-δ irradiated at �2 K by 200 MeV Ag
ions. The inset shows the Tc and T
c0 variation in this fluence range.
76 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
To explain the unexpected fast rate of Tc decrease
at very low fluences of irradiation, we consider
the effect of the SE in creation of point defects
around the amorphous track in YBCO matrix. The
estimated energy of these electrons however is
too low to create defects elastically. We invoke the
inelastic interaction of the low energy electrons
and show that YBCO offers an ideal platform where
SE can create defects by a process analogous to
dissociative recombination seen only in hydrogen
bonded molecules and organic medium [��]. The
point defects are the oxygen disorder in the CuO
chains of YBCO.
in situ low temperature X-ray diffraction study
The 2θ scan patterns of in situ low temperature
x-ray diffraction (XRD) spectra of YBCO film on
irradiation with 200 MeV Ag is shown in figure
3. The detailed values of peak position (2θ), peak
integrated intensity and the full width at half
maximum (FWHM) of (005) peak for all irradiation
fluences were given in TABLE I. The results are
summarized as follows: (i) The appearance of
only sharp (00l) peaks (l = 2 to 7) indicating
epitaxial nature of the film with grain orientation
along c-axis. (ii) No new peaks corresponding to
crystallographic planes other than (00l) up to the
highest fluence of irradiation (2�0�3 ions cm-2)
appear. (iii) Spectra exhibit a sharp reduction in
(00l) peak intensity at low irradiation fluence (iv)
The (00l) peak shift towards lower angle with
increase of irradiation fluence, which is a sign of
expansion of the lattice parameter along the c-
axis (v) The full width at half maximum (FWHM)
of XRD peaks shows an incubation effect up to
��0�2 ions cm-2 and beyond which it increases.
Figure 2. The ρ(T) vs fluence in the mid fluence regime. To fit to the scale, the ρ(T) for the fluence 6.�7 ×
�0�2 ions cm-2 is divided by 3. Inset (a) shows the temperature dependence of resistance of YBCO films
irradiated at a fluence of � × �0�3 ions cm-2. Inset (b) shows the Tc vs fluence in the mid-fluence regime.
Figure 3 Evolution of low temperature (�9 K) in situ X-ray diffraction pattern of a YBa2Cu
3O
7-y thin film
with 200 MeV Ag ion irradiation fluence. In addition to (00l) peaks (l = 2 to 7) due to YBCO, there are
peaks due to the copper sample holder and the LaAlO3 substrate.
Fluence Peak Integrated intensity FWHM
(ion cm-2) centroid in degree
0 3�.6�3 266�.9 ± �6.� 0.2730� ± 0.002�2
�×�0�0 3�.635 2�77.37 ± �3.75 0.2752� ± 0.00�96
3×�0�0 3�.63� 2�32.0 ± �3.�2 0.27505 ± 0.00�95
�×�0�� 3�.6�9 2�0�.� ± ��.37 0.26963 ± 0.00�7
3×�0�� 3�.5�3 23�3.95 ± �0.6� 0.27757 ± 0.00�66
�×�0�2 3�.5�� 2250.� ± ��.69 0.295�5 ± 0.00�97
3×�0�2 3�.257 �7��.�5 ± �2.76 0.�9�05 ± 0.00�33
6×�0�2 3�.�26 �2��.� ±��.�0� 0.72�09 ± 0.007�3
�×�0�3 3�.09� 76�.�� ± 6.359 0.79306 ± 0.00672
2×�0�3 3�.037 267.65 ± 2.�56 0.7��5 ± 0.007��
TABLE I. Evolution of the peak centroid, integral intensity and FWHM with irradiation fluence of the (005)
XRD peak.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 77
Proceedings of the National Seminar : 23 Nov 20�0
To explain the unexpected fast rate of Tc decrease
at very low fluences of irradiation, we consider
the effect of the SE in creation of point defects
around the amorphous track in YBCO matrix. The
estimated energy of these electrons however is
too low to create defects elastically. We invoke the
inelastic interaction of the low energy electrons
and show that YBCO offers an ideal platform where
SE can create defects by a process analogous to
dissociative recombination seen only in hydrogen
bonded molecules and organic medium [��]. The
point defects are the oxygen disorder in the CuO
chains of YBCO.
in situ low temperature X-ray diffraction study
The 2θ scan patterns of in situ low temperature
x-ray diffraction (XRD) spectra of YBCO film on
irradiation with 200 MeV Ag is shown in figure
3. The detailed values of peak position (2θ), peak
integrated intensity and the full width at half
maximum (FWHM) of (005) peak for all irradiation
fluences were given in TABLE I. The results are
summarized as follows: (i) The appearance of
only sharp (00l) peaks (l = 2 to 7) indicating
epitaxial nature of the film with grain orientation
along c-axis. (ii) No new peaks corresponding to
crystallographic planes other than (00l) up to the
highest fluence of irradiation (2�0�3 ions cm-2)
appear. (iii) Spectra exhibit a sharp reduction in
(00l) peak intensity at low irradiation fluence (iv)
The (00l) peak shift towards lower angle with
increase of irradiation fluence, which is a sign of
expansion of the lattice parameter along the c-
axis (v) The full width at half maximum (FWHM)
of XRD peaks shows an incubation effect up to
��0�2 ions cm-2 and beyond which it increases.
Figure 2. The ρ(T) vs fluence in the mid fluence regime. To fit to the scale, the ρ(T) for the fluence 6.�7 ×
�0�2 ions cm-2 is divided by 3. Inset (a) shows the temperature dependence of resistance of YBCO films
irradiated at a fluence of � × �0�3 ions cm-2. Inset (b) shows the Tc vs fluence in the mid-fluence regime.
Figure 3 Evolution of low temperature (�9 K) in situ X-ray diffraction pattern of a YBa2Cu
3O
7-y thin film
with 200 MeV Ag ion irradiation fluence. In addition to (00l) peaks (l = 2 to 7) due to YBCO, there are
peaks due to the copper sample holder and the LaAlO3 substrate.
Fluence Peak Integrated intensity FWHM
(ion cm-2) centroid in degree
0 3�.6�3 266�.9 ± �6.� 0.2730� ± 0.002�2
�×�0�0 3�.635 2�77.37 ± �3.75 0.2752� ± 0.00�96
3×�0�0 3�.63� 2�32.0 ± �3.�2 0.27505 ± 0.00�95
�×�0�� 3�.6�9 2�0�.� ± ��.37 0.26963 ± 0.00�7
3×�0�� 3�.5�3 23�3.95 ± �0.6� 0.27757 ± 0.00�66
�×�0�2 3�.5�� 2250.� ± ��.69 0.295�5 ± 0.00�97
3×�0�2 3�.257 �7��.�5 ± �2.76 0.�9�05 ± 0.00�33
6×�0�2 3�.�26 �2��.� ±��.�0� 0.72�09 ± 0.007�3
�×�0�3 3�.09� 76�.�� ± 6.359 0.79306 ± 0.00672
2×�0�3 3�.037 267.65 ± 2.�56 0.7��5 ± 0.007��
TABLE I. Evolution of the peak centroid, integral intensity and FWHM with irradiation fluence of the (005)
XRD peak.
7� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
In the low fluence regime, the sharp decrease of Tc, Tc0
and integrated intensity of (00l) peaks with irradiation
fluence are due to creation of oxygen disorder in CuO
chains of YBCO by the swift heavy ion induced low
energy secondary electrons over a large range around
each amorphous ion latent track [��,�3]. The defect
creation is possible due to the crystal structure of YBCO,
which permits varying oxygen coordination of Cu
ions in the chains [�6] and offers an ideal situation for
trapping of the secondary electron and consequent
oxygen disorder in CuO chains inelastically. The
increase of FWHM beyond the ��0�2 ions cm-2 is
due to the proximity of the strain region around the
amorphous latent tracks, which is the cause of the
evolution of the two-step superconducting transition
in the mid fluence regime.
conclUsion
In conclusion, the observation of integral intensity
of XRD peaks, Tc and T
c0 decrease at a much faster
rate with ion fluence is explained on the basis of
SHI induced secondary electrons, which create
oxygen disorder by electron capture process in the
CuO chains of a fully oxygenated YBCO structure.
The strain regions contribute to increase of FWHM
above a critical fluence of �0�2 ions cm-2. In this
fluence range, the radially strained region around
them amorphous latent tracks tends to overlap
and a two-step superconducting transition
evolves instead of a single transition.
acKnoWleDGements
The authors are thankful to the Pelletron group
of IUAC, New Delhi, for providing a good quality
scanned beam for irradiation. This work is
supported by the UFUP funding of IUAC, New
Delhi. One of the authors, R Biswal, would like
to thank the Council of Scientific and Industrial
Research (CSIR), Government of India, for the
award of SRF (F. No. 09/�73/(0�26)/200�/EMR-I).
references
[�] R. Simon and A. Smith, Superconductors: Conquering Technology’s New Frontier (Plenum, New York, �9��).
[2] M. K. Wu, R. J. Ashburn, C. J. Torng et al., Phys. Rev. Lett. 5� (�9�7) 90�.
[3] R. L. Fleischer, P. B. Price, R. M. Walker, J. Appl. Phys. 36 (�965) 36�5.
[�] A. Dunlop, D. Lesueur, J. Morillo et al., C. R. Acad. Sci. Ser. II 309 (�9�9) �277.
[5] A. Iwase, S. Sakaki, T. Iwata, T. Nihira, Phys. Rev. Lett. 5� (�9�7) 2�50.
[6] H. Dammak, A. Barbu, D. Lesueur, N. Lorenzelli, Philos. Mag. Lett. 67 (�993) 253.
[7] S. Klaumunzer, G. Schumacher, Phys. Rev. Lett. 5� (�9�3) �9�7.
[�] H. Bruining, Physics and Applications of Secondary Electron Emission (McGraw-Hill Book Company, Inc., New York, �95�).
[9] H. W. Seo, Q. Y. Chen, M. N. Iliev et al., Phys. Rev. B 72
(2005) 05250�.
[�0] B. W. Veal, A. P. Paulikas, Hoydoo You et al., Phys. Rev.
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[��] R. Biswal, J. John, D. Behera, et al., Supercond. Sci.
Technol. 2� (200�) 0�50�6.
[�2] E. Balanzat, Radiat. Eff. ��0 (�9�9) 99.
[�3] R. Biswal, J. John, P. Mallick et al., J. Appl. Phys. �06
(2009) 0539�2.
[��] D. Bourgault, S. Bouffard, H. Toulemonde et al., Phys.
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[�5] E. M. Jackson, B. D. Weaver, G. P. Summers et al. Phys.
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6 (�993) 359.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 79
Proceedings of the National Seminar : 23 Nov 20�0
THEORETICAL STUDY OF THE EFFECT OF MAGNETIC FIELD IN CMR MANGANITES
Saswati Panda� and G.C. Rout2
�Trident Academy of Technology, F2/A, Chandaka Industrial Estate,Bhubaneswar -75�02�, India.
Email: [email protected] Matter Physics Group P. G. Deptt. of Applied Physics and Ballistics,
F. M. University, Balasore - 7560�9, India.
Abstract
We present a model calculation to study the magnetoresistivity (MR) through the
interplay between the magnetization and structural transitions for the manganite
systems. The manganite system is described by the double exchange model in presence
of core-spin in association with the static and dynamic band Jahn-Teller distortion
present in the eg band. The model Hamiltonian is solved using Zubarev’s Green’s
function technique and the resistivity is calculated us- ing Drude-Lorentz formula.
Keywords: Colossal magneto-resistance; Jahn-Teller effect; Magnetization.
1 introduction
Mixed valent manganites with perovskite structure
having general formula R�−x
AxMnO
3 (where R is a
trivalent rare earth element like La, Pr, Nd and A is a
divalent alkaline earth element like Sr, Ca, Ba), have
been studied for almost 50 years. These materials
are insulators at high temperatures and poor
metals at low temperatures. This insulator to metal
transition is accompanied with a phase transition
from high temperature paramagnetic to low
temperature ferromagnetic phase. This transition
occurs around the transition temperature, Tc.
Application of magnetic field near Tc greatly
reduces the resistivity i.e. negative magneto-
resistance is observed. The magnetoresistance
arises from the spin-dependent scattering
process of conduction electrons. The electrical
resistivity (ρ) in the ferromagnetic region has
been studied by a numbers of authors[�, 2, 3].
In the low temperature region just below Tc, ρ
decreases rapidly with the decrease of T. For
Contributed Paper
�0 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
T < 0.5Tc typically the variation is much less rapid,
but it is quite different from what is observed in
a metallic ferromagnet. Application of a magnetic
field (up to 6 Tesla) causes significant decrease in
the resistivity of La�−x
AxMnO
3 samples particularly
in the compositions 0.� < x < 0.5. These materials
are generally ferromagnetic with well-defined
Tcs. colossal magnetoresistance (CMR) close to
�00% has been observed in many polycrystalline
and single crystals of compositions La�−x
AxMnO
3,
but applied field is quite high (5-6 Tesla). In
La1-x
PbxMnO
3 high CMR is found around room
temperature or above [�].
The CMR effect is discovered by Jonker
and van Santen [5]. In �95� zener had proposed
the double exchange (DE) model to explain the
CMR phenomenon [6]. The DE model essentially
explains the behaviour of magnetoresistance
with respect to magnetization. Based on the study
of the RMn�−x
CrxO
3 system where isoelectronic
Cr3+ replacesMn�+, it has been shown recently
that DE is essential for the occurrence of CMR
in manganites [7]. However, A. J. Millis et. al. [�]
pointed out that, the DE model alone is not
enough to explain the CMR effect in manganites,
because DE produces wrong Tc by a large factor
and the resistivity that grows with reducing
temperature (insulating behaviour) even below Tc.
He claimed that Jhan-Teller (JT) effect is necessary
to explain the curvature of the resistivity close to
Tc. Millis et. al. [9, �0, ��, �2] argued that the physics
of manganites is dominated by the interplay
between a strong electron-phonon coupling and
the large Hund’s coupling effect that optimizes
the electronic kinetic energy by the generation of
a ferromagnetic phase. The spin-charge coupling
varies with temperature and composition, and
it increases across the metal insulator transition
[�3]. Recently Rout et. al. have shown that the
static JT distortion causes a IM transition near the
ferromagnetic Curie temperature in manganites
[��, �5]. The large value of the electron-phonon
coupling in manganites is clear in the regime
below x = 0.2, where a static J-T distortion plays
a key role in the physics of the material and a
dynamic J-T effect may persist at higher hole
densities [�6], without leading to long-range
order, but producing important fluctuations that
localize electrons by splitting the degenerate eg
levels at a given MnO6 octahedron.
The unusual properties of the CMR
effect are regarded as a co-operative phenomena
associated with a structural change due to a tiny
atomic displacement, competing with magnetic
interactions and charge fluctuations between
different valencies of manganese cations. In this
respect, Mn3+ orbitals show JT effect [�7] and
hence the degeneracy can easily be lifted by
lowering the crystal symmetry costing the lattice
distortion energies. Therefore it is believed that
the CMR should be the result of the local distortion
which is often defined as ”polarons”. The itinerary
of such polarons gives rise to the conduction. It
is well recognized that the JT interaction plays
a crucial role to determine the super-exchange
interactions in these transition metal oxides.
It is observed that there is charge ordering, in
addition to orbital ordering, in the manganese
oxide systems. More recently, Rout and co-workers
have reported the theoretical investigations of
the effect of charge ordering on the physical
properties like magnetization [��], velocity of
sound[�9], magnetic spin susceptibility [20] and
Raman spectra[2�] for the manganite system
(the calculation of resistivity is in progress). In the
present work we address the theoretical study of
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | ��
Proceedings of the National Seminar : 23 Nov 20�0
the magnetoresistance in the manganese oxide
system in presence of JT distortion.
2 formalism
The electron Hamiltonian is
The four coupled Green’s functions are
(�)
where α = 0 − � and Eα (0) is given by
(5)
The self-energy of the electrons is given by
(6)
with Sα = (ω−Eα(k−q))(�+2νq)+ω
q(�−2nα). The four
quasi- particle energies in presence of JT distortion,
induced magnetism Mc in eg band and external
magnetic field B are given by Eα,k−q,σ = N0(k − q) −
μ − σB − (−�)αGe + σJMc. The term νq = [eωq/kBT −
�]−� is the Bose-Einstein distribution function and
nα is the electron occupation number. However, in
the present model calculation, ωq is taken as the
constant single frequency of Einstein model.
The electronic resistivity of the
manganite system can be found out from the
Drude-Lorentz formula ρ−� = ne2τ/m, where m
and e are the mass and charge of the electron, n
is the concentration of electron. The relaxation
time of electron (τ) due to electron-phonon
interaction is given by τ−� = Σατα−�. The τα (for α =
� − �) can be calculated from the imaginary part
of the self-energy of the four Green’s functions
Aα(k, ω) [see eqn. �]. The relaxation time τ is
an active function of the frequency (ω), the
magnetic field (B) and other physical parameters
of the manganite system. The resistivity of the
system is calculated numerically for different
parameters using the self-consistent values of
induced magnetization, Mc in eg band, the static
JT distortion, e and the magnetization Md in the
The Hamiltonian H0 describes the kinetic
energy of the eg electron in the first term, the JT
interaction in second term, the double exchange
interaction in third term, core-spin interaction in
fourth term and the kinetic energy of the core state
in the last term. Nkσ = (N
0(k) − μ − σµbB), N
dσ = Nd −
µ − σglµbBd and G, J, JH are the strength of electron
lattice interaction in presence of a tetragonal
distortion e, s−d exchange coupling constant and
Heisenberg coupling constant respectively. The
Hamiltonian describing the coupling of phonons
to the Jahn-Teller distorted eg band electrons
(�)
(2)
with f(q) as the dynamic electron-phonon
coupling constant and Aq = b
q + b†
−q is the phonon
displacement vector. Hp = Σ
q ω
qb†
qb
q is the free
phonon Hamiltonian, where ωq is the phonon
energy b†q (b
q) is the creation (annihilation)
operator of the phonons. So, the total Hamiltonian
is H = H0 + H
ep + H
p. The double time, single particle
electron Green’s functions are calculated using
the zubarev’s Green’s function technique [22] as
follows
(3)
�2
�2 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
core t2g
band. The expressions for Mc, e and Md
are given below.
(7)
(�)
(9)
where f (y) = �/(� + ey/kBT ) is the Fermi distribution
function. The quasi-particle energies are written
as ω�, 2
= Nd − µ ± M
2R with M2
2R = M
2 2 + J2
H Sd2
and M2 = Bd − J
HMd. All the physical quantities are
scaled with respect to the conduction band width
(W). The dimensionless quantities are: ,
, , , , ,
, , and
3 results and Discussion
In order to study the temperature
dependence of the core-magnetization md and
the JT lattice strain e we have solved the eqns. (�)
and (9) self-consistently for a set of parameters like
the DE coupling g, the JT coupling g3 and the core-
spin coupling g2 for different external magnetic
fields. The results are shown in Fig.�. It is observed
that the increase of the external magnetic field
produces a tail at the Curie temperature thereby
destroying its robust character. Further the
external magnetic field suppresses the lattice
strain e in the interplay region, which in turn
enhances the induced magnetization (mc) in the
eg band electrons.
Fig.� The self-consistent plots of md, e, mc vs. t for
fixed values of g = 0.025, g2 = 0.033�, g
3 = 0.0�92 and
for different values of applied magnetic field b.
The calculated resistivity shows a
very high value between the low temperature
ferromagnetic metallic state and the high
temperature paramagnetic phase as shown in
Fig.2. On increasing external magnetic field to the
order of a few Tesla, the resistivity is suppressed
considerably in the insulating phase as observed
in the experimental measurements of the
manganite system.
��
�2
g = J W
g2 =
JH
Wg
3 =
G
Wt =
kBT
We =
e
Wg
� =
r0
f 2(q)
W
eq =
quF
W W=
ω W
p = ω
q
Wg=
η W .
Fig.2 The plot of resistivity ρ vs. t for fixed values of g, g
2, g
3 as taken in Fig.�, g
� = 0.�, e
q = 0.00�, p = 0.05,
W= 0.00�, g= 0.003 and for different values of applied magnetic field b.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �3
Proceedings of the National Seminar : 23 Nov 20�0
References
[�] J. M. De Teresa et. al. Phys. Rev. B 5� ���7 (�996).[2] P. Schiffer et. al. Phys. Rev. Lett. 75 3336 (�995).[3] A. Urushibara et. al. Phys. Rev. B 56 ���03 (�995).[�] R. Mahendiran et. al. J. Phys. D: Appl. Phys. 2� �7�3
(�995).[5] G. H.Jonker and J. H. Van Santen Physica �6 337
(�950).[6] C. zener Phys. Rev. �� ��0 (�95�); C. zener Phys. Rev.
�2 �03 (�95�).[7] R. Gundakaram et. al. J. Solid State Chem. �27 35�
(�996).[�] A.J. Millis, P. B. Littlewood and B. I. Shraiman Phys.
Rev. Lett. 7� 5��� (�955).[9] A. J. Millis, B. I. Shraiman and R. Mueller Phys. Rev.
Lett. 77 �75 (�996).[�0] A. J. Millis, B. I. Shraiman and R. Muller Phys. Rev. B 5�
53�9 (�996).[��] A. J. Millis nature 392 ��7 (�99�).[�2] A. J. Millis Phys. Rev. Lett. �0 �35� (�99�).
[�3] H. R¨oder, J. zhang and A. R. Bishop Phys. Rev. Lett. 76 �356 (�996).
[��] G. C. Rout, N. Parhi, S. N. Behera, Physica B �0� 23�5 (2009).
[�5] G. C. Rout, N. Parhi, S. N. Behera, Int. J. Mod. Phys.B 20 2093 (2006).
[�6] A. J. Millis, R. Muller and B. I. Shraiman Phys. Rev. B 5� 5�05 (�996).
[�7] J. B. Goodenough Phys. Rev. �00 56� (�955).[��] G. C. Rout, S. Panda and S. N. Behera, Physica B �0�
�273 (2009).[�9] G. C. Rout and S. Panda, J. Phys.: Condens. Matter 2�
��600� (2009).[20] G. C. Rout and S. Panda Solid State Comm. �50 6�3
(20�0).[2�] G. C. Rout, S. Panda and S. N. Behera J. Phys.: Condens.
Matter 22 376003 (20�0).[22] D. N. zubarev Sov. Phy. Usp. 3 320 (�960).
�� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
Abstract
The generation of nanostructures by energetic ion beams is highlighted. The energy
loss of the ions inside the materials medium takes the decisive role in forming the
nanostructures. Low energy ions loose energy by direct elastic knock-on process
and create vacancies, interstitials and even clusters of these defects finally getting
implanted in the target. All these defects help formation of nanoparticles embedded in
the substrate at controlled depth and density depending on ion energy and fluence. In
case of high energetic ions with energy shooting up to hundreds of million electron volt
(MeV), inelastic interaction of the projectile ion with the target electrons is the dominant
mode of energy loss. This so called electronic energy loss facilitates formation of
nanoparticles embedded in a matrix. Irradiation perpendicular to the target surface as
well as grazing incident ion beams have been used for the formation of nanostrucures.
The periodic nanoripples, equally spaced multiple nanodots are some of the examples
of nanostructures created by ion irradiation with grazing incidence ion beams on the
film surface. The unique attributes of low energy ions and high energy ions have also
utilized together to form monodispersed nanoparticles localized along ion tracks.
ENERGETIC ION BEAM: A TOOL FOR SYNTHESIS OF NANOSTRUCTURES
P. Mallick�,2,* and N. C. Mishra2,#
�P.G. Department of Physics, North Orissa University, Takatpur, Baripada-7570032P.G. Department of Physics, Utkal University, Vanivihar, Bhubaneswar-75�00�
*[email protected]; #[email protected]
Keywords: Ion beam; nanostructures; nanoparticles.
1. introduction:
In recent years nanostructured materials have
attracted a great deal of attention because of
their extremely small size and large surface-to-
volume ratio. These attributes of nanomaterials
have led to size dependent chemical and physical
properties, which are quite different from those of
bulk materials of the same chemical composition
[�]. These exotic properties thus emerging in
the nanoscale of the particle size have made
nanoparticle research as one of the hottest topics
in the present scenario due to their varieties of
technological applications. The new technology
which emerges with nanoparticles is known as
nanotechnology. The nanoparticles are generally
defined as small solid objects whose physical
dimension lies in the range from a few nm to
about hundred nm. Their size is sufficiently large to
represent the crystalline properties but still small
enough where significant differences in chemical,
structural, electrical and magnetic properties
from their bulk counterparts are observed. These
unusual properties are seen in nanoparticles due
to their extremely large surface to volume ratio
and quantum confinement effect.
Nanostructures can be synthesized
by various physical (sputtering, pulsed laser
deposition, electron-beam evaporation etc.) and
chemical (atomic layer epitaxy, sol–gel, spray
pyrolysis, anodic deposition etc.) methods by
following two basic approaches such as bottom
up and top down. In bottom up approach, the
atoms are brought together to form particles
of nanometric dimension whereas in top down
approach, large size grains are broken to form
nanodomains. Ion beam based synthesis method
utilizes both the approaches for generation of
nanostructure.
In this paper, we discuss the interaction of
energetic ions with materials medium in different
energy regimes. The possibilities of synthesis of
nanostructures with different ion energies are
reviewed.
2. ion-matter interaction:
While traversing through the materials medium,
energetic ions transfer high localized density of
the energy to the target medium. The solid may
receive for a very short time (~�0−�7 to �0−�5 s)
within a very tiny volume (~�0−�7 to �0−�6 cm3) the
same energy density which else is only found in
the vicinity of an exploding hydrogen bomb by
the impact of just one energetic heavy ion [2].
The energy deposited by the energetic ion beam
into materials medium is commonly described by
the “stopping power” which is the measure of the
energy transfer per unit path length of a projectile
along its trajectory. The energy of the ion is
transferred to the solid almost instantaneously
into a highly localized volume of nm-dimensions
in two nearly independent processes: (i) nuclear
energy loss (Sn) and (ii) electronic energy loss (S
e).
Finally the projectile ion gets implanted when
it loses all its energy in the material medium.
Depending on the energy, the ion beams are
mainly divided in to two categories: (i) low energy
ions (LEI) and (ii) swift heavy ions (SHI). The low
energy ions have energy in the range from some
keV to a few MeV and the ion with energy some
tens of MeV and beyond is considered as swift
heavy ion.
In the keV range of ion energy, the Sn
induced processes dominate and lead to creation
of atomic size point defects and clusters of
defects in the target. When the velocity of the ion is
comparable to the Bohr velocity of the electron, the
Se induced processes lead to coherent excitation and
ionization of electrons along the ion path. When Se
exceeds a materials dependent threshold value Seth
,
a trail of defects or ammorphized latent tracks are
expected to be implanted in the material along the
ion path [3]. Track registration is a consequence of
extremely intense solid state excitation generated
by the SHI along its path within a very short
interval of time. This process thus involves driving
the system far from equilibrium state in a highly
Contributed Paper
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �5
Proceedings of the National Seminar : 23 Nov 20�0
Abstract
The generation of nanostructures by energetic ion beams is highlighted. The energy
loss of the ions inside the materials medium takes the decisive role in forming the
nanostructures. Low energy ions loose energy by direct elastic knock-on process
and create vacancies, interstitials and even clusters of these defects finally getting
implanted in the target. All these defects help formation of nanoparticles embedded in
the substrate at controlled depth and density depending on ion energy and fluence. In
case of high energetic ions with energy shooting up to hundreds of million electron volt
(MeV), inelastic interaction of the projectile ion with the target electrons is the dominant
mode of energy loss. This so called electronic energy loss facilitates formation of
nanoparticles embedded in a matrix. Irradiation perpendicular to the target surface as
well as grazing incident ion beams have been used for the formation of nanostrucures.
The periodic nanoripples, equally spaced multiple nanodots are some of the examples
of nanostructures created by ion irradiation with grazing incidence ion beams on the
film surface. The unique attributes of low energy ions and high energy ions have also
utilized together to form monodispersed nanoparticles localized along ion tracks.
ENERGETIC ION BEAM: A TOOL FOR SYNTHESIS OF NANOSTRUCTURES
P. Mallick�,2,* and N. C. Mishra2,#
�P.G. Department of Physics, North Orissa University, Takatpur, Baripada-7570032P.G. Department of Physics, Utkal University, Vanivihar, Bhubaneswar-75�00�
*[email protected]; #[email protected]
Keywords: Ion beam; nanostructures; nanoparticles.
1. introduction:
In recent years nanostructured materials have
attracted a great deal of attention because of
their extremely small size and large surface-to-
volume ratio. These attributes of nanomaterials
have led to size dependent chemical and physical
properties, which are quite different from those of
bulk materials of the same chemical composition
[�]. These exotic properties thus emerging in
the nanoscale of the particle size have made
nanoparticle research as one of the hottest topics
in the present scenario due to their varieties of
technological applications. The new technology
which emerges with nanoparticles is known as
nanotechnology. The nanoparticles are generally
defined as small solid objects whose physical
dimension lies in the range from a few nm to
about hundred nm. Their size is sufficiently large to
represent the crystalline properties but still small
enough where significant differences in chemical,
structural, electrical and magnetic properties
from their bulk counterparts are observed. These
unusual properties are seen in nanoparticles due
to their extremely large surface to volume ratio
and quantum confinement effect.
Nanostructures can be synthesized
by various physical (sputtering, pulsed laser
deposition, electron-beam evaporation etc.) and
chemical (atomic layer epitaxy, sol–gel, spray
pyrolysis, anodic deposition etc.) methods by
following two basic approaches such as bottom
up and top down. In bottom up approach, the
atoms are brought together to form particles
of nanometric dimension whereas in top down
approach, large size grains are broken to form
nanodomains. Ion beam based synthesis method
utilizes both the approaches for generation of
nanostructure.
In this paper, we discuss the interaction of
energetic ions with materials medium in different
energy regimes. The possibilities of synthesis of
nanostructures with different ion energies are
reviewed.
2. ion-matter interaction:
While traversing through the materials medium,
energetic ions transfer high localized density of
the energy to the target medium. The solid may
receive for a very short time (~�0−�7 to �0−�5 s)
within a very tiny volume (~�0−�7 to �0−�6 cm3) the
same energy density which else is only found in
the vicinity of an exploding hydrogen bomb by
the impact of just one energetic heavy ion [2].
The energy deposited by the energetic ion beam
into materials medium is commonly described by
the “stopping power” which is the measure of the
energy transfer per unit path length of a projectile
along its trajectory. The energy of the ion is
transferred to the solid almost instantaneously
into a highly localized volume of nm-dimensions
in two nearly independent processes: (i) nuclear
energy loss (Sn) and (ii) electronic energy loss (S
e).
Finally the projectile ion gets implanted when
it loses all its energy in the material medium.
Depending on the energy, the ion beams are
mainly divided in to two categories: (i) low energy
ions (LEI) and (ii) swift heavy ions (SHI). The low
energy ions have energy in the range from some
keV to a few MeV and the ion with energy some
tens of MeV and beyond is considered as swift
heavy ion.
In the keV range of ion energy, the Sn
induced processes dominate and lead to creation
of atomic size point defects and clusters of
defects in the target. When the velocity of the ion is
comparable to the Bohr velocity of the electron, the
Se induced processes lead to coherent excitation and
ionization of electrons along the ion path. When Se
exceeds a materials dependent threshold value Seth
,
a trail of defects or ammorphized latent tracks are
expected to be implanted in the material along the
ion path [3]. Track registration is a consequence of
extremely intense solid state excitation generated
by the SHI along its path within a very short
interval of time. This process thus involves driving
the system far from equilibrium state in a highly
Contributed Paper
�6 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
localized region, which cannot be achieved by any
other technique [�].
Two independent models exit to
describe the formation of ion tracks in the
materials medium such as (i) Coulomb explosion
(explosion-like repulsion of the ionized atoms
along the ions path) [5,6] and (ii) thermal spike
model [7-�0]. Coulomb explosion model predicts
that the electrons around the ion path move
away radially after receiving energy from the
projectile ion leaving behind only the positively
charged ions along the projectile ion path. The
repulsive interaction between these ions along
the projectile path leads to bond breaking as a
result of which the materials along the ion path
get damaged. Thermal spike model predicts that
the energy initially transferred to the electrons is
finally transferred to the lattice atom, which can
lead to a local temperature increase. The thermal
spike model thus predicts confinement of heat
energy within the small volume along the ion
path. If the consequence temperature rise exceeds
the melting temperature of the target, the target
melts in this confined volume.
In both the cases, due to large electronic
energy loss of the ion, a cylindrical amorphized
zone of some nm in diameter can form along
the ions path. Energy dissipation into the cold
surrounding resulted in rapid solidification within
some tens to some hundreds of picoseconds,
and depending on the material, leave behind a
defect-rich or even amorphous track of typically
�0 nm in diameter and some μm length [��]. A
preferential chemical etching along the defective
regions or ion track can be exploited to produce
high-precision filter membranes [6,�2,�3], drug
release devices [�3,��], isolated nanopores for
single biomolecule molecule detection [�5], and
nanopore ion pumps [�6]. The electronic devices
such as transistors, resistors and transformers can
be constructed out of these nanopores by filling
appropriate materials [�7,��].
Energetic ions are an excellent tool for
the creation of nano-structures on the surface or
in the near-surface region of a solid [��]. Ion beams
in the past have played a very crucial role in the
formation, modification and characterization of
nanoparticles. Utilizing the ion energy, fluence and
materials medium one can synthesis nanoparticle
both by SHI and LEI. Different possibilities of
synthesizing nanostructures with energetic ion
beam are discussed in the following sections.
3.1. synthesis of nanostructure by low energy
ions (lei):
The low energy ions (LEI) are utilized for synthesis
of nanostructures either by ion bombardment or
by ion implantation method. In this process the
generation of nanostructures is confined mainly
to the surface or near surface region only. For the
ion implanted case, the implanted ion takes the
important role for the formation of final product.
3.1.1. Synthesis of nanostructures by LEI
bombardment:
The generation of surface nanostructures has
been achieved by bombarding the materials
surface with LEI. The creation of periodic arrays
of nanoripples and nanodots by sputtering with
low-energy ions in metals and semiconductors
has been reported by various groups [�,�9,20]. The
surface relief induced by sputtering under certain
conditions can take the shape of ripples similar to
those created by the wind on the sea or the sand
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �7
Proceedings of the National Seminar : 23 Nov 20�0
[�]. The nanoripples generated at the surfaces
can be further used as a template for growing
nanowires. The surface structuring of InSb by the
�-3 MeV Au ion bombardment is explained on the
basis of ion beam induced sputtering [�9]. SnO2
films bombareded with 250 keV Xe+ ion lead to
the generation of nanodots. The size and shape of
nanodots formed with Xe+ ion bombardment were
different for different substrate. The generation of
defects under Xe+ ion bombardment facilitates
the growth of SnO2 nanodots [20].
3.1.2. Synthesis of nanoparticles by ion
implantation:
In this process the suitable substrate material
is implanted by the projectile ion. Ordinarily
the range of the LEI is less as compared to the
substrate thickness so the ions will be implanted
in the near surface region. Then the implanted
material is annealed at high temperature and the
nanoparticles form due to phase segregation.
If the implanted ion and matrix are immiscible,
the thermal annealing leads to the formation of
embedded nanoparticle of the implanted ions.
The unique features of ion implantation method
over other synthesis methods are
(i) Ion implantation overcomes restrictions
imposed by chemical incompatibility of
dopants and the host matrix faced by
chemical routes. Almost any substrate can
be doped with any ion.
(ii) The formation of nanoparticles is of
extreme chemical purity (including isotope
selection).
(iii) This can be used for submicron pattern
resolution i.e. ion implantation can be carried
out with masks or with finely focussed beams
( �0 nm diameter).
(iv) Ion implantation allows well dispersed
nanoparticles embedded in a matrix. The
size and density of nanoparticles can be
controlled by controlling ion fluence and
annealing temperature.
(v) This allows to control the location of
nanoparticle formation beneath the surface
by controlling the energy and hence range
of the projectile ion.
(vi) Diffusion of implantated species can be
mediated through irradiation induced
vacancies and interstials i.e. radiation
enhanced diffusion.
There are some limitations of ion implantation
method and care must be taken to avoid unwanted
reactions between nanocrystals and substrates
and the atomic displacement damages caused
by energetic ions. If the ions are implanted at low
energies, their depth profile intersects the surface
so that incoming ions may sputter previously
implanted ones. if the ions are implanted at higher
energies (to overcome problem of sputtering of
implanted atoms), the duration of the implantation
may be prohibitive because the concentration at
the mean range decreases in inverse proportion
to the profile width, which varies almost in
proportion to the ion energy [�].
3.2. synthesis of nanostructures by swift heavy
ions (shi):
Swift heavy ion irradiation has been utilized to
generate nanostructures in the surface as well as
along the ion path while traversing in the materials
medium. In this process the role of electronic
energy loss is important. The ion species do not
take the decisive role in forming the final material
�� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
as these ions travel much dipper into the substrate
after crossing the film thickness (material).
SHI instantaneously deposit a huge
amount of energy in the nano scale regions which
results into a nm-scale zone of extreme non-
equilibrium conditions with high atomic mobility
and reduced density. Energy dissipation into the
cold surrounding then results in rapid solidification
in picoseconds time domain, and depending on
the material, leave behind a columnar defect or
even amorphous track along the ion path. Surface
instability caused by the stresses generated
in the ion track and subsequent anisotropic
deformation by SHI bombardment (‘‘hammering
effect’’, since the material expands perpendicular
and shrinks along the beam direction as if treated
with a hammer) led to the generation of surface
nanostructure [��]. The generation and processing
of complex nano-structures is realized from thin
NiO-films taking advantage of a surface instability
caused by the stresses generated in the ion track,
and utilizing the hammering effect [2�]. For
example, periodic pattern of NiO walls (~ �00–200
nm thickness and � μm height and distance) have
been formed on the surface of �30 nm thick NiO
layer grown on SiO2 when irradiated with 230 MeV
Xe ions at a tilt angle of 750 [��].
The formation of cylindrical ion track
of radius ~ � nm is formed in SnO2 matrix under
the bombardment of �00 MeV Ag ions, which
acts as the nucleating centre for the growth of
uniform size (radius ~ � nm) nanocrystals of SnO2
inside the ion track [22]. Swift heavy ion induced
nucleation and growth processes of nanocrystals
leads to synthesis of narrow size distributed
nanocrystals in the SnO2 matrix. The formation of
uniform size nanoparticles of NiO at the tip of the
ion track has also been reported [23]. Deposition
of huge amount of energy by the SHI along the
ion path results into the molten ion track which
experiences a compressive stress due to thermal
expansion. Large stress gradients accelerate the
molten material from the track region toward
the surfaces and results into the formation of
nanoparticles (7-9 nm in diameter) at the tip of
the ion tracks [23].
The formation of multiple, equally spaced
dots of SrTiO3, each separated by a few tens of
nanometers have been created after irradiation
of the surface by SHI under grazing angles of a
few degrees with respect to the surface plane. The
number of dots and their spacing can be controlled
by controlling the incident angle [2�]. SHI irradiation
on SiOx led to the phase separation of Si and silica
under dense electronic excitation due to reduction
process. As the SHI irradiation causes the evolution
of oxygen from the film and a phase separation
changes the system into Si nanocrystal and a more
stoichiometric SiO2 matrix [25].
3.3. synthesis of nanostructures by using both
lei and shi:
The synthesis of nanostructures utilizing both the
role of LEI and SHI can be achieved. The basic idea
is to control the size distribution of nanocrystals
which can be formed by ion implantation and
subsequent SHI irradiation. The SHI irradiation
led to the generation of cylindrical ion track or
defective regions which may act as the nucleating
centre for the growth the uniform size nanocrystals
of size about the size of ion track. Mohanty et
al. [26] have reported that the formation of Si
nanoparticle and narrow size distribution of the
particles could be achieved by irradiating the Si
ion implanted silica with 70 MeV Si ions.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �9
Proceedings of the National Seminar : 23 Nov 20�0
4. conclusion:
The applicability of energetic ion beam for the
synthesis of nanostructures has been discussed
with some of the important results in this
line of study has been outlined and the basic
principles behind these results are discussed.
For example, the periodic nanoripples surface
can be synthesized with the help of low energy
ion beam. Both nanodots and buried layer can
be synthesized by ion implantation method. The
multiple nanodots separated by equal spacing
can be created by SHI irradiation with grazing
incidence. Ion implantation combined with swift
heavy ion irradiation also used for the synthesis of
nanostructures.
references:
[� D.K. Avasthi and J.C. Pivin, Curr. Sci. 9�, 7�0 (20�0) (and references therein).
[2] D. Fink and L.T. Chadderton, Brazilian J. Phys. 35, 735 (2005)
[3] J. Vetter, R. Scholz, D. Dobrev and L. Nistor, Nucl. Instrum. Methods Phys. Res. B ���, 7�7 (�99�) (and references therein).
[�] P. Mallick, C. Rath, Jai Prakash, D.K. Mishra, R.J. Choudhary, D.M. Phase, A. Tripathi, D.K. Avasthi, D. Kanjilal and N.C. Mishra, Nucl. Instrum. Methods Phys. Res. B 26�, �6�3 (20�0).
[5] R.L. Fleischer, P.B. Price and R.M. Walker, J. Appl. Phys. 36 (�965) 36�5.
[6] R.L. Fleischer, P.B. Price and R.M. Walker, Nuclear Tracks in Solids, University of California Press, �975.
[7] F. Seitz and J.S. Koehler, Solid State Phys. 2 (�956) 305.
[�] z.G. Wang, Ch. Dufor, E. Paumier, F. Pawlak and M. Toulemonde, J. Phys.: Condens. Matter 6 (�99�) 6733.
[9] M. Toulemonde, Ch. Dufor, z.G. Wang and E. Paumier, Nucl. Instrum. Methods Phys. Res. B �22 (�996) 26.
[�0] M. Toulemonde, J.M. Costantini, Ch. Dufor, A. Meftah, E. Paumier and F. Studer, Nucl. Instrum. Methods Phys. Res. B ��6 (�996) 37.
[��] W. Bolse, Nucl. Instrum. Methods Phys. Res. B 2��, � (2006) (and references therein).
[�2] J.-H. zollondz and A. Weidinger, Nucl. Instrum. Methods Phys. Res. B 225, �7� (200�).
[�3] h t t p : / / w w w. w h a t m a n . p l c . u k / p r o d u c t s /nuclepore/index.htm
[��] R. Spohr, Ion Tracks and Microtechnology (Vieweg, Braunschweig, �990).
[�5] A. Mara, z. Siwy, C. Trautmann, J. Wan and F. Kamme, Nano Lett. �, �97 (200�).
[�6] z. Siwy and A. Fulinski, Phys. Rev. Lett. �9, �9��03 (2002).
[�7] J. Chen and R. K.nenkamp, Appl. Phys. Lett. �2, �7�2 (2003).
[��] D. Fink, P.S. Alegaonkar, A.V. Petrov, A.S. Berdinsky, V. Rao, M. Müller, K.K. Dwivedi, and L.T. Chadderton, Radiat. Meas. 36, 605 (2003).
[�9] A.G. Perez-Bergquist, K. Li, Y. zhang and L. Wang, Nanotech. 2�, 325602 (20�0)
[20] T. Mohanty, Y. Batra, A. Tripathi, and D. Kanjilal, J. Nanosci. Nanotechnol. 7, � (2007)
[2�] W. Bolse, B. Schattat, and A. Feyh, Appl. Phys. A 77, �� (2003).
[22] T. Mohanty, P. V. Satyam and D. Kanjilal, J. Nanosci. Nanotechnol. 6, �(2006)
[23] B. Schattat, W. Bolse, S. Klaumünzer, I. zizak and R. Scholz, Appl. Phys. Lett. �7, �73��0 (2005).
[2�] E. Akcöltekin, T. Peters, R. Meyer, A. Duvenbeck, M. Klusmann, I. Monnet, H. Lebius and M. Schleberger, Nature Nanotech. 2, 290 (2007).
[25] P.S. Chaudhari, T.M. Bhave, D. Kanjilal and S. Bhoraskar, J. Appl. Phys. 93, ��6 (2003).
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90 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
MICROSCOPIC THEORY OF ULTRASONIC ATTENUATION IN CHARGE AND SPIN ORDERED CUPRATE SYSTEMS
G. C. Rout�∗ and S. K. Panda2
�∗Condensed Matter Physics Group, P. G. Dept. of Applied Physics and Ballistics,
F. M. University, Balasore, India-756 0�9. 2 K. D. Science College , Pochilima , Hinjilicut-76� �0� , Ganjam , Orissa , India.
Corresponding author, Email: [email protected], Tel: +9�-99379��69�
Abstract
In this communication we report a model study of the ultrasonic attenuation in the
high-Tc cuprate systems in normal state. The model consists of the charge density wave
(CDW) and spin density wave (SDW) interactions in presence of doping concentrations.
The phonons are assumed to be coupled to the conduction electron density in
harmonic approximation. The phonon Green’s function is calculated by using Zubarev’s
technique of Green’s function, the imaginary part of which is proportional to ultrasonic
attenuation coefficient. The frequency and temperature dependent attenuation
coefficient is calculated numerically by varying the different model parameters of the
system like electron-phonon coupling, CDW coupling and the SDW coupling. The results
are discussed to explain the experimental observations of different levels of doping and
temperatures. This model calculation outlines how to calculate the individual CDW and
SDW order parameters from the observed experimental peak positions.
Keywords: SDW; CDW ; High-Tc superconductors ; Ultrasonic attenuation.
1 introduction.
Ultrasonic measurements have been of great
importance in investigating the bulk properties of
materials arising due to the lattice instabilities and
phase transitions. A number of structural anomalies
signifying the lattice instabilities and phase
transitions in high temperature superconductors
around the critical temperatures Tc. Apart from
the attenuation peak in the vicinity of the critical
temperatures Tc, there is also an attenuation peak
around 200K[�]. The measurements on show that
the attenuation peaks at Tc and above 200K are
associated with the interaction of sound waves
with the excitations in the CuO2 planes. However,
the peak around Tc is observed to shift to high
temperatures with increasing ultrasonic frequency
indicating the characteristic of a thermally activated
relaxation peak. The attenuation measurements
on Bi2Sr
2CaCu
2O
8 show an attenuation peak
around 250K indicating the character of a phase
transition rather than a relaxation. Understanding
the normal state anomalous behavior of the high-
Tc superconductors remains one of the major
challenges posed by these materials. In the under-
doped region, a well defined feature is the opening
of a pseudo-gap at the characteristic temperature
T*(T* >Tc) A few microscopic theories of ultrasonic
attenuation has been reported to explain the
experimental data for the copper oxide systems.
Earlier Rout and co-workers have reported a
theoretical model for ultrasound study[2, 3],
Raman spectra [�, 5] on the basis of a model study
displaying the interplay of the antiferromagnetism
and hybridization. In the present work, we
consider a model study for ultrasonic attenuation
describing the interplay of charge density wave
(CDW) and spin density wave (SDW) interactions
in high-Tc superconductors. We consider here the
model study to describe the normal phase of the
system. Here the insulating CDW interaction is
assumed to play the role of pseudo-gap which is
more prominent in the under-doped region for the
system. The organization of the present work is as
follows. The formalism for the model calculation is
presented in section-2. The results and discussion
and finally the conclusion are given in section-3.
2 formalism
In high-Tc systems, there exists antiferromagnetic
spin order with commensurate wave vector Q in
Neutron scattering[6] and Raman scattering[7]
measurements. Due to low dimensionality of the
high-Tc systems, there exists nesting of the Fermi
surface leading to the establishment of the spin
density wave (SDW) phase. The electronphonon
interaction in two dimensional high-Tc system
gives rise to the charge order CDW state with
an interaction strength V1 = 2g2
Q /Nω
Q, where g
Q
is the electronphonon interaction with a nesting
vector Q. Based on our earlier model study[�, 9]
the mean-field Hamiltonian can be written as
H0 = ∑(∈
0(k) - μ)c†
k,σ ck,σ + D
c ∑ c†
k+Q, σck,σ
k,σ k,σ
+ Ds ∑ (c†
k+Q, ↑ ck,↑ - c
†k+Q, ↓ c
k,↓ ) (�) k
where Dc(D
s) are the CDW(SDW) order parameters
and c†k6
(ck,6
) is the creation and annihilation
electron operators. In order to study the elastic
properties, we consider the phonon coupling to the
conduction band within harmonic approximation
with the Hamiltonian
H� = ∑ ƒ(q) c$
k+q, σ c
k, σ A
q + ∑ ω
q b$
qb
q (2)
k+q, σ q
where Aq=(b†
q+b†
−q) with b†
q(b
q) is the
creation(annihilation) operator of the phonon
with frequency ωq and wave vector q. The retired
phonon Green’s function is defined as Dq,q′(t, t′) =
−iQ(t, t′) < [Aq(t); A
q′(t′)] >. Using total Hamiltonian,
the Green’s function[6] takes the general form
D
q,q′(ωq) =
ωq [ω2 - ω2
q - ∑ (ω,q)]-�
π
where the phonon self-energy reduces to ∑(ω, q) =
�πωqχ
q,q(ω). The ultrasonic attenuation co-efficient
α(ω, T) for ultrasonic sound waves of frequency ω,
phonon wave vector q at temperature T is given
by the imaginary part of the phonon selfenergy.
Mathematically, it is written as
α(ω,T, q) = - [ � �πImχqq
(ω,T,q)]
ωq
where χqq
(ω, T, q) is the electron response function
Contributed Paper
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 9�
Proceedings of the National Seminar : 23 Nov 20�0
MICROSCOPIC THEORY OF ULTRASONIC ATTENUATION IN CHARGE AND SPIN ORDERED CUPRATE SYSTEMS
G. C. Rout�∗ and S. K. Panda2
�∗Condensed Matter Physics Group, P. G. Dept. of Applied Physics and Ballistics,
F. M. University, Balasore, India-756 0�9. 2 K. D. Science College , Pochilima , Hinjilicut-76� �0� , Ganjam , Orissa , India.
Corresponding author, Email: [email protected], Tel: +9�-99379��69�
Abstract
In this communication we report a model study of the ultrasonic attenuation in the
high-Tc cuprate systems in normal state. The model consists of the charge density wave
(CDW) and spin density wave (SDW) interactions in presence of doping concentrations.
The phonons are assumed to be coupled to the conduction electron density in
harmonic approximation. The phonon Green’s function is calculated by using Zubarev’s
technique of Green’s function, the imaginary part of which is proportional to ultrasonic
attenuation coefficient. The frequency and temperature dependent attenuation
coefficient is calculated numerically by varying the different model parameters of the
system like electron-phonon coupling, CDW coupling and the SDW coupling. The results
are discussed to explain the experimental observations of different levels of doping and
temperatures. This model calculation outlines how to calculate the individual CDW and
SDW order parameters from the observed experimental peak positions.
Keywords: SDW; CDW ; High-Tc superconductors ; Ultrasonic attenuation.
1 introduction.
Ultrasonic measurements have been of great
importance in investigating the bulk properties of
materials arising due to the lattice instabilities and
phase transitions. A number of structural anomalies
signifying the lattice instabilities and phase
transitions in high temperature superconductors
around the critical temperatures Tc. Apart from
the attenuation peak in the vicinity of the critical
temperatures Tc, there is also an attenuation peak
around 200K[�]. The measurements on show that
the attenuation peaks at Tc and above 200K are
associated with the interaction of sound waves
with the excitations in the CuO2 planes. However,
the peak around Tc is observed to shift to high
temperatures with increasing ultrasonic frequency
indicating the characteristic of a thermally activated
relaxation peak. The attenuation measurements
on Bi2Sr
2CaCu
2O
8 show an attenuation peak
around 250K indicating the character of a phase
transition rather than a relaxation. Understanding
the normal state anomalous behavior of the high-
Tc superconductors remains one of the major
challenges posed by these materials. In the under-
doped region, a well defined feature is the opening
of a pseudo-gap at the characteristic temperature
T*(T* >Tc) A few microscopic theories of ultrasonic
attenuation has been reported to explain the
experimental data for the copper oxide systems.
Earlier Rout and co-workers have reported a
theoretical model for ultrasound study[2, 3],
Raman spectra [�, 5] on the basis of a model study
displaying the interplay of the antiferromagnetism
and hybridization. In the present work, we
consider a model study for ultrasonic attenuation
describing the interplay of charge density wave
(CDW) and spin density wave (SDW) interactions
in high-Tc superconductors. We consider here the
model study to describe the normal phase of the
system. Here the insulating CDW interaction is
assumed to play the role of pseudo-gap which is
more prominent in the under-doped region for the
system. The organization of the present work is as
follows. The formalism for the model calculation is
presented in section-2. The results and discussion
and finally the conclusion are given in section-3.
2 formalism
In high-Tc systems, there exists antiferromagnetic
spin order with commensurate wave vector Q in
Neutron scattering[6] and Raman scattering[7]
measurements. Due to low dimensionality of the
high-Tc systems, there exists nesting of the Fermi
surface leading to the establishment of the spin
density wave (SDW) phase. The electronphonon
interaction in two dimensional high-Tc system
gives rise to the charge order CDW state with
an interaction strength V1 = 2g2
Q /Nω
Q, where g
Q
is the electronphonon interaction with a nesting
vector Q. Based on our earlier model study[�, 9]
the mean-field Hamiltonian can be written as
H0 = ∑(∈
0(k) - μ)c†
k,σ ck,σ + D
c ∑ c†
k+Q, σck,σ
k,σ k,σ
+ Ds ∑ (c†
k+Q, ↑ ck,↑ - c
†k+Q, ↓ c
k,↓ ) (�) k
where Dc(D
s) are the CDW(SDW) order parameters
and c†k6
(ck,6
) is the creation and annihilation
electron operators. In order to study the elastic
properties, we consider the phonon coupling to the
conduction band within harmonic approximation
with the Hamiltonian
H� = ∑ ƒ(q) c$
k+q, σ c
k, σ A
q + ∑ ω
q b$
qb
q (2)
k+q, σ q
where Aq=(b†
q+b†
−q) with b†
q(b
q) is the
creation(annihilation) operator of the phonon
with frequency ωq and wave vector q. The retired
phonon Green’s function is defined as Dq,q′(t, t′) =
−iQ(t, t′) < [Aq(t); A
q′(t′)] >. Using total Hamiltonian,
the Green’s function[6] takes the general form
D
q,q′(ωq) =
ωq [ω2 - ω2
q - ∑ (ω,q)]-�
π
where the phonon self-energy reduces to ∑(ω, q) =
�πωqχ
q,q(ω). The ultrasonic attenuation co-efficient
α(ω, T) for ultrasonic sound waves of frequency ω,
phonon wave vector q at temperature T is given
by the imaginary part of the phonon selfenergy.
Mathematically, it is written as
α(ω,T, q) = - [ � �πImχqq
(ω,T,q)]
ωq
where χqq
(ω, T, q) is the electron response function
Contributed Paper
92 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
for long wave longitudinal phonons. The response
function is a two particle Green’s function which
is calculated from the electronic Hamiltonian
in absence of electron-phonon interaction. The
physical quantities involved in the calculation are
made dimensionless by dividing them by hopping
integral 2t0. They are
z� =
Dc ; z
2 =
Ds ; g
�=N (O)V
�; g
2 = N (O)U;
t =
kBT
2t0 2t
0 2t
0
ω = ω ;
p= ω
c = ω
; e= η
; qƒ = qu
F
ω0 2t
0 2t
0 2t
0 2t
0
3 results and Discussion
The CDW coupling (g� = 0.055) and SDW coupling
(g2 = 0.06�) are so chosen that the transition
temperature of CDW phase is greater than that of
the SDW (i.e tCDW
= 0.056, tSDW
= 0.0� in absence
of doping). The CDW and SDW phases co-exist for
temperature t < tSDW
. For the given values of (z�)
and (z2) at a fixed temperature, the attenuation
coefficient is calculated numerically.
Fig. 1 The plot of vs ω for CDW gap parameter
z1=0.04927, SDW gap parameter z
2=0.04437,
temperature t=0.01, bare phonon frequency p=0.1
for EP couplings s=0.155, 0.17, 0.20.
The Fig.� shows ultrasound energy dependence of
the ultrasonic attenuation co-efficient for different
electron-phonon (EP) couplings. For coupling
constant s = 0.�55, we observe two absorption
Fig. 2 The plot of α vs ω for z1=0.04927, z
2=0.04437,
phonon energy qf=0.001, EP coupling s=0.15 for
temperatures t=0.03, 0.04, 0.05.
peaks at energies ω� . 2.� and ω
2 . 0.�5 for the
optical phonon at q= 0. The reduced energy ω is
defined as ω = ω/ω0 = c/p, where c is the reduced
frequency and p is the bare phonon frequency.
Corresponding to the given value p = 0.�, we
observe two ultrasonic peaks i.e. high energy peak
at c� = 0.2� and low energy peak at c
2 = 0.0�5. From
the poles of the Green’s function, we expect two
ultrasonic peaks with energies 2(z� +z
2 ) and 2(z
� −
z2). For temperature t=0.0�, the gap parameters are
found to be (z�) = 0.0�97 and (z2) = 0.0��37. Hence
the calculated peak value should appear at 2(z� +
z2 ) = 0.��� and 2(z
� − z
2)=0.0��. These calculated
values are slightly less than the observed values of
(c�) and (c
2) which are enhanced due to the effect
of the electron-phonon interaction. It is concluded
that the magnitudes of the order parameters (z�)
and (z2) can be calculated from the observed peak
positions in the ultrasound measurements. It is
found that the position of higher energy peak is
shifted to still higher energies and the position of
the low energy peak is shifted to lower energies
due to the electron-phonon interaction present
in the system. The electron-phonon coupling, s
= 0.�55 is comparable to s = 0.�� - 0.�5 obtained
from other theoretical calculations reported.
Further, the ultrasonic absorption increases
with the increase of EP coupling resulting in the
increase of the height of the resonance peaks.
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 93
Proceedings of the National Seminar : 23 Nov 20�0
The temperature dependence of ultrasonic
attenuation is shown in Fig.2. With the increase
of temperature, the high energy peak at ω� shifts
to lower energies and the low energy peak at !˜2
shifts to higher energies. Further, spectral height
at energy ω� is suppressed with increase of
temperature, while the spectral height at energy ω2
is enhanced with increase of temperature. It is seen
from temperature dependence of gap parameters
(z� and z
2) that the magnitudes of both the gaps
decrease with the increase of temperature. As a
result, the peak at ω� decreases because the value
2(z� +z
2) decreases with increase of temperature.
The peak position at ω2 increases with increase
of temperature, because the effective energy
2(z� −z
2) at energy ω
2 increases with increase of
temperature. Hence from peak positions at ω� .
2(z� +z
2) and ω
2 . 2(z
� −z
2) the magnitudes of the
individual gap values at different temperatures
can be calculated by using the formula developed
by the present model.
For the electron-phonon(EP) coupling
constant s = 0.�55 to 0.20, we observe two
ultrasonic absorption peaks corresponding to
the high energy peak at energy 2(z� +z
2) and low
energy peak at energy 2(z� −z
2). The EP coupling
is comparable to the value observed for the
CDW superconductors. Similar suppression of
spectral height with increase of temperature is
observed in NCCO and LSCO system indicating
the phase change in the system. In conclusion we
emphasize that our model calculation will guide
the experimentalist to calculate the individual
order parameters of the mutually competing
interactions like CDW and SDW at different
temperatures, impurity concentrations and
external magnetic fields.
references
[�] G. Cannelli, R. Cantelli and F. Cordero, Int. J. Mod. Phys. B5 (�9��) ��57.
[2] G.C. Rout, B. N. Panda and S. N. Behera, Solid Stat Comm. �05 (�99�) �7.
[3] K. C. Bishoyi, G.C. Rout and S. N. Behera, Indian J. Phys 76A(�) (2002) �7.
[�] G.C. Rout, B. N. Panda and S. N. Behera, Solid State Comm. �06 (�99�) �69.
[5] G.C. Rout, K. C. Bishoyi and S. N. Behera, Physica c �20 (2005) 37.
[6] G. Shirane et al., Phys. Rev. Lett. 59 (�9�7) �6�3.[7] K. B. Lyons et al., Phys. Rev. B 37 (�9�7) 2353.[�] S. K. Panda and G.C. Rout, Physica C. �69 (2009) 702.[9] G. C. Rout and S. K. Panda, Physica C. (20�0)
(Communicated)
9� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
CONDUCTING POLYMERS BASED SENSORS : AN ARTIFICIAL NEURAL NETWORK APPROACH
B.K. Parija, P.K.Sahoo, B. Prusty, A.R. Routray and M.C. Adhikary
P.G. Dept. of Applied Physics & Ballistics, F.M. University, Balasore
Corresponding author : [email protected]
ABSTRACT
A brief overview of research and development in the field of conducting polymers
based sensors with Artificial Neural Network is presented. The conducting polymers
with electrical and optical properties can be used in sensor devices either participate in
sensing mechanism or immobilize the component responsible for sensing the analyte.
In this aspect, the electronic tongue using Artificial Neural Network (ANN) approach
for taste classification based on the biological sensory systems , has been developed
rapidly during the last few years. The electronic tongue system (ETS) uses several sensors
fabricated from nanostrutured thin films of different polymers that are deposited on
the top of an interdigitated micro electrode. Introduction of new series of integrated
artificial Intelligence/conducting polymer based sensor gives analytical responses,
which look irreversible and non producible, are combined by an artificial intelligence
trained computer by which reproducible output, based on the created model and pattern
by the computerized system, can be predicted . Pattern recognition techniques are
described with Artificial Neural Network.So these electro-active conducting polymers
cover a broad spectrum of applications from solid-state technology to biotechnology
and sensor technology.
Key Words : Artificial neural network (ANN), Electronic tongue, Pattern recognition, Conducting Polymers,
ASMOD, Processing elements, Neuro fuzzy.
1.introduction:
A new class of polymers known as intrinsically
conducting polymers (CPs) or electroactive
conjugated polymers exibit interesting electrical
and optical properties , which are found only
in inorganic systems. Electrically conducting
polymers differ from aa the familiar inorganic
semiconductors ( silicon and germanium ) in two
important features that polymers are molecular in
nature and lack long-range order [�]. Conducting
Polymers contain π-electron backbone which
is responsible for their unusual electronic
properties such as electrical conductivity, low
energy optical transitions, low ionization potential
and high electron affinity and are also used
to enhance speed, sensitivity and versatility of
sensors. Properties of CPs depend strongly on
doping level, ion size of dopant, protonation level
and water content. CPs finding ever-increasing
use in diagnostic medical reagents and with a
distinguishable chemical memory, are prominent
new materials for fabrication of industrial sensors.
2. sensors Based on transduction :
Sensors may be classified depending on the
mode of transduction into the categories like
potentiometric sensors, amperometric sensors,
piezoelectric sensors, calorimetric / thermal
sensors and optical sensors.
i) Potentiometric sensors :
The potentiometric sensors may be either symmetric
or asymmetric. In symmetric potentiometric sensors
, the selective membrane is symmetrically bathed
by two electrolyte solutions and an external sample
solution. In asymmetric potentiometric sensors,
there is no internal filling solution. Hence , the sensor
membrane is only in contact with one aqueous
phase i.e. the sample , while the internal contact is
with a solid-state ionic or electronic conductor. In
potentiometric sensors, cell potential is monitored in
zero current condition ( equilibrium ) [2]. Example
includes a sensor for glucose by glucose oxidase
with the activity of fluoride ions through the action
of a second catalytic reaction on an organofluorine
compound.
ii) Amperometric Sensors :
In amperometric sensors, signal is propotional
to the concentration of analyte species. Suitable
target species are electroactive species that are
capable of being oxidized or reduced, with the
oxidation or reduction potential being zero. In a
biosensor , concentration of an enzyme substrate
is measured indirectly through the consumption
of oxygen by oxidase enzyme catalyzed reactions
or by the generation of the hydrogen peroxide
(H2O
2). Oxygen and H
2O
2 being the co-substrates
and the product of several enzyme reactions
are detected for amperometric estimation.
The electrochemical biosensors are based on
mediated or unmediated electrochemistry for
electron transfer [3].
iii) Piezoelectric Sensors :
In piezoelectric sensor , an acoustic wave is
propagated by an externally applied alternating
current between two electrodes or interdigited
electrode fingers deposited on a piezoelectric
substrate such as quartz. The subclasses of
piezoelectric transducers are based on the way of
acoustic wave propagated between the electrodes.
Most applications of these devices have been
found for gas phase monitoring , where hydrogen
sulphide,carbon dioxide, oxygen, nitrogen dioxide,
molecular hydrogen, mercury, toluene and actone
sensors have been fabricated[2].
iv) Calorimetric/Thermal Sensors :
Thermistors, whose resistance changes markedly
with temperature, are often employed as cheap,
sensitive temperature sensors. The most commenly
used approach in the thermal enzyme probes[�]
is related to the enzyme directly attached to the
thermistor. It is observed that the heat evolved in
Contributed Paper
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 95
Proceedings of the National Seminar : 23 Nov 20�0
CONDUCTING POLYMERS BASED SENSORS : AN ARTIFICIAL NEURAL NETWORK APPROACH
B.K. Parija, P.K.Sahoo, B. Prusty, A.R. Routray and M.C. Adhikary
P.G. Dept. of Applied Physics & Ballistics, F.M. University, Balasore
Corresponding author : [email protected]
ABSTRACT
A brief overview of research and development in the field of conducting polymers
based sensors with Artificial Neural Network is presented. The conducting polymers
with electrical and optical properties can be used in sensor devices either participate in
sensing mechanism or immobilize the component responsible for sensing the analyte.
In this aspect, the electronic tongue using Artificial Neural Network (ANN) approach
for taste classification based on the biological sensory systems , has been developed
rapidly during the last few years. The electronic tongue system (ETS) uses several sensors
fabricated from nanostrutured thin films of different polymers that are deposited on
the top of an interdigitated micro electrode. Introduction of new series of integrated
artificial Intelligence/conducting polymer based sensor gives analytical responses,
which look irreversible and non producible, are combined by an artificial intelligence
trained computer by which reproducible output, based on the created model and pattern
by the computerized system, can be predicted . Pattern recognition techniques are
described with Artificial Neural Network.So these electro-active conducting polymers
cover a broad spectrum of applications from solid-state technology to biotechnology
and sensor technology.
Key Words : Artificial neural network (ANN), Electronic tongue, Pattern recognition, Conducting Polymers,
ASMOD, Processing elements, Neuro fuzzy.
1.introduction:
A new class of polymers known as intrinsically
conducting polymers (CPs) or electroactive
conjugated polymers exibit interesting electrical
and optical properties , which are found only
in inorganic systems. Electrically conducting
polymers differ from aa the familiar inorganic
semiconductors ( silicon and germanium ) in two
important features that polymers are molecular in
nature and lack long-range order [�]. Conducting
Polymers contain π-electron backbone which
is responsible for their unusual electronic
properties such as electrical conductivity, low
energy optical transitions, low ionization potential
and high electron affinity and are also used
to enhance speed, sensitivity and versatility of
sensors. Properties of CPs depend strongly on
doping level, ion size of dopant, protonation level
and water content. CPs finding ever-increasing
use in diagnostic medical reagents and with a
distinguishable chemical memory, are prominent
new materials for fabrication of industrial sensors.
2. sensors Based on transduction :
Sensors may be classified depending on the
mode of transduction into the categories like
potentiometric sensors, amperometric sensors,
piezoelectric sensors, calorimetric / thermal
sensors and optical sensors.
i) Potentiometric sensors :
The potentiometric sensors may be either symmetric
or asymmetric. In symmetric potentiometric sensors
, the selective membrane is symmetrically bathed
by two electrolyte solutions and an external sample
solution. In asymmetric potentiometric sensors,
there is no internal filling solution. Hence , the sensor
membrane is only in contact with one aqueous
phase i.e. the sample , while the internal contact is
with a solid-state ionic or electronic conductor. In
potentiometric sensors, cell potential is monitored in
zero current condition ( equilibrium ) [2]. Example
includes a sensor for glucose by glucose oxidase
with the activity of fluoride ions through the action
of a second catalytic reaction on an organofluorine
compound.
ii) Amperometric Sensors :
In amperometric sensors, signal is propotional
to the concentration of analyte species. Suitable
target species are electroactive species that are
capable of being oxidized or reduced, with the
oxidation or reduction potential being zero. In a
biosensor , concentration of an enzyme substrate
is measured indirectly through the consumption
of oxygen by oxidase enzyme catalyzed reactions
or by the generation of the hydrogen peroxide
(H2O
2). Oxygen and H
2O
2 being the co-substrates
and the product of several enzyme reactions
are detected for amperometric estimation.
The electrochemical biosensors are based on
mediated or unmediated electrochemistry for
electron transfer [3].
iii) Piezoelectric Sensors :
In piezoelectric sensor , an acoustic wave is
propagated by an externally applied alternating
current between two electrodes or interdigited
electrode fingers deposited on a piezoelectric
substrate such as quartz. The subclasses of
piezoelectric transducers are based on the way of
acoustic wave propagated between the electrodes.
Most applications of these devices have been
found for gas phase monitoring , where hydrogen
sulphide,carbon dioxide, oxygen, nitrogen dioxide,
molecular hydrogen, mercury, toluene and actone
sensors have been fabricated[2].
iv) Calorimetric/Thermal Sensors :
Thermistors, whose resistance changes markedly
with temperature, are often employed as cheap,
sensitive temperature sensors. The most commenly
used approach in the thermal enzyme probes[�]
is related to the enzyme directly attached to the
thermistor. It is observed that the heat evolved in
Contributed Paper
96 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
the enzymatic reactions is lost to the suurounding
solution without being detected by thermistor
resulting in the decrease in sensitivity of the
biosensor.
v) Optical Sensors :
Optical sensors are based on the measurements
of light absorbed or emitted as a consequence of
a biochemical reaction. Light waves are guided by
means of optical fibers to suitable detectors. Such
sensors can be used for measurement of pH, O2,
CO2 etc.
3.sensors Based on applications :
Sensors may be classified depending on the mode
of applications into the categories like Chemical
sensors- gas sensors, pH sensors, ion—selective
sensors, alcohol sensors, humidity sensors and
Biosensors.
i) Chemical Sensors :
Chemical sensors convert a chemical state into
an electric signal. In such sensors, a sensitive
layer is in chemical contact wuth the analyte. A
change in the chemistry of the sensitive layer
(a reaction) is produced after the exposure to
analyte. The sensitive layer is on a platform that
allow stransconduction of the change to electric
signals.Every chemical sensor is divided into
two domains, the physical transuducer and the
chemical interface.And conducting polymers
used for gas sensors with acid,base or oxidizing
characteristics shows good results. Sensors are
designed by the electrochemical deposition
of appropriate polymer across a gap of �2µm
between two gold microband electrodes. Most
of the widely used CPs are polythiophene and
its derivatives , polypyrrole polyaniline and
composites of these polymers[5].
ii) Biosensors :
Biosensor is an analytical device incorporating a
biological or biological derived material, either
inyimately associated or integrated within a
physico-chemical transducer. The change in
electronic conductivity of conducting polymers in
response to change in pH has been made use of
in fabricating sensors for biomolecules.Here the
CPs are formed by a combination of donor and
acceptor systems.
4. artificial intelligence methods in conducting
Polymer :
Conducting polymer based sensors which
possess an array of attributes rarely found in
other materials. Appropriate manipulation of
the material composition can be used to induce
specific molecular (stimuli) recognition properties,
and electronic properties of the materials are such
that electrical information can be generated and
processed[6].Moreover, the electrochemically
controlled chemical nature of the polymers is
such that response actuation is readily achieved.
Although conducting polymer based sensors
have been used in variety of applications, there
have been very few cases that they have been
utilized in a commercial products . This is due
to the dynamic nature of these materials which
causes reproducibility problems . Considering
the passive approaches used to control the
dynamic intelligence of these smart materials,
there has not been much success in keeping their
behaviour under control. So the adaptive and
dynamic artificial intelligence methods can be
introduced to challenge and control the output
behaviour of an intelligent conducting polymer
based sensory system. Therefore, an approach is
taken by an intelligent process control system
in which the physical and chemical properties
of such smart materials can be dynamically
controlled. And for this the application of
artificial intelligence, neuro-fuzzy and neural
network [7], in conducting polymer based
sensors are adopted.
i) Artificial Neural Network :
Artificial neural networks (ANN) are massively
parallel inter connected networks of simple
organizations (processing elements) which
are intended to interact with the objects of
real world in the same way as the biological
neural systems do [��. These parallel distributed
models are potentially capable of performing
nonlinear modelling and adaptation without
any assumptions about the model . In very broad
terms, the ANN may be defined as an attempt to
capture the human brains capabilities for solving
complex problems. The term “artificial neural
network” is used to describe a number of different
models intended to imitate some functions of
human brains.
In a neural network, input patterns
(data signals) are connected to the processing
elements of the input layer and the outputs of
these elements are connected to the inputs
of the elements in the next layer .There is one
processing element ( PE ) for each input in
the input layer and one PE for each output in
the output layer . In addition, a few arbitrary
hidden layers inty also be inserted between the
input and output layers . The resulting network
configuration is shown in Figure- �, and is known
as the multilayer perceptron (MLP)[�]. The use of
more hidden layers permits better handling of
more complex nonlinear functions.
Figure-� : Network cofiguration of ANN
ii)Adaptive Spline Modelling of Observation
Data (ASMOD) :
The ASMOD algorithm is an off-line iterative
modelling approach which has the potential of
real-time learning, dealing with time-varying
systems . It has been successfully implemented
in a wide range of applications . ASMOD uses B-
splines to represent general nonlinear and coupled
dependencies in multivariable observation
data. B-Splines are commonly used in computer
graphics and CAD systems for representing
three dimensional curves and surfaces with
high accuracy. In the ASMOD algorithm the
output variable is modelled as a sum of several
low dimensional sub models, where each
submodel only depends on a small subset of the
input variables. The decomposition of the high
dimensional input space into low dimensional
additive subspecies makes the model transparent
to the user, and at Inputs Sigmoid Hard limit. The
ASMOD modelling scheme can be mapped into a
three layered feed-forward neural network, using
P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 97
Proceedings of the National Seminar : 23 Nov 20�0
the enzymatic reactions is lost to the suurounding
solution without being detected by thermistor
resulting in the decrease in sensitivity of the
biosensor.
v) Optical Sensors :
Optical sensors are based on the measurements
of light absorbed or emitted as a consequence of
a biochemical reaction. Light waves are guided by
means of optical fibers to suitable detectors. Such
sensors can be used for measurement of pH, O2,
CO2 etc.
3.sensors Based on applications :
Sensors may be classified depending on the mode
of applications into the categories like Chemical
sensors- gas sensors, pH sensors, ion—selective
sensors, alcohol sensors, humidity sensors and
Biosensors.
i) Chemical Sensors :
Chemical sensors convert a chemical state into
an electric signal. In such sensors, a sensitive
layer is in chemical contact wuth the analyte. A
change in the chemistry of the sensitive layer
(a reaction) is produced after the exposure to
analyte. The sensitive layer is on a platform that
allow stransconduction of the change to electric
signals.Every chemical sensor is divided into
two domains, the physical transuducer and the
chemical interface.And conducting polymers
used for gas sensors with acid,base or oxidizing
characteristics shows good results. Sensors are
designed by the electrochemical deposition
of appropriate polymer across a gap of �2µm
between two gold microband electrodes. Most
of the widely used CPs are polythiophene and
its derivatives , polypyrrole polyaniline and
composites of these polymers[5].
ii) Biosensors :
Biosensor is an analytical device incorporating a
biological or biological derived material, either
inyimately associated or integrated within a
physico-chemical transducer. The change in
electronic conductivity of conducting polymers in
response to change in pH has been made use of
in fabricating sensors for biomolecules.Here the
CPs are formed by a combination of donor and
acceptor systems.
4. artificial intelligence methods in conducting
Polymer :
Conducting polymer based sensors which
possess an array of attributes rarely found in
other materials. Appropriate manipulation of
the material composition can be used to induce
specific molecular (stimuli) recognition properties,
and electronic properties of the materials are such
that electrical information can be generated and
processed[6].Moreover, the electrochemically
controlled chemical nature of the polymers is
such that response actuation is readily achieved.
Although conducting polymer based sensors
have been used in variety of applications, there
have been very few cases that they have been
utilized in a commercial products . This is due
to the dynamic nature of these materials which
causes reproducibility problems . Considering
the passive approaches used to control the
dynamic intelligence of these smart materials,
there has not been much success in keeping their
behaviour under control. So the adaptive and
dynamic artificial intelligence methods can be
introduced to challenge and control the output
behaviour of an intelligent conducting polymer
based sensory system. Therefore, an approach is
taken by an intelligent process control system
in which the physical and chemical properties
of such smart materials can be dynamically
controlled. And for this the application of
artificial intelligence, neuro-fuzzy and neural
network [7], in conducting polymer based
sensors are adopted.
i) Artificial Neural Network :
Artificial neural networks (ANN) are massively
parallel inter connected networks of simple
organizations (processing elements) which
are intended to interact with the objects of
real world in the same way as the biological
neural systems do [��. These parallel distributed
models are potentially capable of performing
nonlinear modelling and adaptation without
any assumptions about the model . In very broad
terms, the ANN may be defined as an attempt to
capture the human brains capabilities for solving
complex problems. The term “artificial neural
network” is used to describe a number of different
models intended to imitate some functions of
human brains.
In a neural network, input patterns
(data signals) are connected to the processing
elements of the input layer and the outputs of
these elements are connected to the inputs
of the elements in the next layer .There is one
processing element ( PE ) for each input in
the input layer and one PE for each output in
the output layer . In addition, a few arbitrary
hidden layers inty also be inserted between the
input and output layers . The resulting network
configuration is shown in Figure- �, and is known
as the multilayer perceptron (MLP)[�]. The use of
more hidden layers permits better handling of
more complex nonlinear functions.
Figure-� : Network cofiguration of ANN
ii)Adaptive Spline Modelling of Observation
Data (ASMOD) :
The ASMOD algorithm is an off-line iterative
modelling approach which has the potential of
real-time learning, dealing with time-varying
systems . It has been successfully implemented
in a wide range of applications . ASMOD uses B-
splines to represent general nonlinear and coupled
dependencies in multivariable observation
data. B-Splines are commonly used in computer
graphics and CAD systems for representing
three dimensional curves and surfaces with
high accuracy. In the ASMOD algorithm the
output variable is modelled as a sum of several
low dimensional sub models, where each
submodel only depends on a small subset of the
input variables. The decomposition of the high
dimensional input space into low dimensional
additive subspecies makes the model transparent
to the user, and at Inputs Sigmoid Hard limit. The
ASMOD modelling scheme can be mapped into a
three layered feed-forward neural network, using
9� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa
Proceedings of the National Seminar : 23 Nov 20�0
B-spline basis functions as the nonlinearities of
the hidden layer, and a linear transfer function for
the output layer.
5. conclusion :
The majority of sensor devices utilize many
polymers with definite roles, either in the sensing
mechanism or through immobilizing the species
responsible for sensing of the analyte components.
This has become possible only because polymers
may be tailored for particular properties, are easily
processed.Application of artificial intelligence
methods (neural network and neuro-fuzzy
methods) to enhance the performance of the
conducting polymer based ion detectors has
been addressed. This new computer based data
processing has been developed for pattern
recognition applications. It has been found
that the patterns and models created by neural
network and ASMOD algorithm can predict the
type and the concentration of ions existing in the
operational environment with acceptable level
of accuracy. A combination of these methods is
recommended to achieve an optimum intelligent
computer based system to address a new and
novel dynamic process control and online
prediction.
references :
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[3] Chaubey A and Malhotra B D , Mediated biosensors review, Biosensors and Bioelectronics,�7,2002 , ���-�56.
[�] Mosbach K and Danielsson B, Thermal bioanalyzers in flow stream enzyme thermister devices, Anal Chem., 5�, �9�6,2979-29�3.
[5] Barlett P N and Long-Chung S K , Conducting polymer gas sensors part III : results for four different polymers, Sensors & Actuators B,�0,�997, 99-�03.
[6] Talde A., Sadk O. and Wallace G.G., J. of Mat Sys., �, �993, �23.
[7] Kahane T., Self Organization and Associative Memory, Springer, �9�9.
[�] A.R. Routray & M.C.Adhikary : Image Compression based Wavelet and Quantization with Optimal Huffman Code, International Journal of Computer Applications, August 20�0, Vol 5 ,No 2 , P-6-9.