TECH-BRIEF 1 May 16, 2013

EDITORIAL

Every day we wake to learn, discover and invent, hard work and determination

can elicit the hidden traits and interest in an individual. We all have different

interest and capabilities. Our editorial team has tried best to give everyone an

opportunity to share their knowledge. Tech-brief is not a boring old newsletter, its

brainchild of students with fresh ideas which encompasses lots of learning with

lots of fun.

This issue is outcome of hard work of all students of electrical and electronics

engineering. Read it guys it‟s the best you can make out of your time, learn and

enjoy.

Thanks to all who contributed in publishing this issue of tech-brief.

Team Tech-Brief

TECH-BRIEF TEAM

Editors

Prakriti Rajbhandari

Rakesh Katuwal

Aahana Karki

Designer

Prajun Dani

_____________________________________

Learn from yesterday, live for today, hope for

tomorrow. The important thing is not to stop

questioning!!!!

Albert Einstein

_________________________________

DEPARTMENT OF ELECTRICAL AND

ELECTRONIC ENGINEERING

An Initiative of SEEE Kathmandu University

TECH-BRIEF 2 May 16, 2013

Li-Fi: It’s more than Wi-Fi

Rakesh K. Katuwal - EE(C)/IIIrd year

Light reaches nearly everywhere, so communication can

ride along for nearly free. Think of a TV remote and

you‟ll soon realize the possibilities of communications

using visible light-also dubbed as Li-Fi.

Most of us are familiar with Wi-Fi (Wireless Fidelity),

which uses 2.4-5GHz RF to deliver wireless Internet

access around our homes, schools, offices and in public

places. We have become quite dependent upon this

nearly ubiquitous service. But, like most technologies, it

has its limitations.

While Wi-Fi can cover an entire house, these days its

bandwidth is typically limited to 50-100 megabits per

second (Mbps), using the IEEE802.11n standard. This is

a good match to the speed of most current Internet

services, but insufficient for moving large data files like

HDTV movies, music libraries and video games.

The more we become dependent upon „the cloud‟ or our

own „media servers‟ to store all of our files, including

movies, music, pictures and games, the more we will

want bandwidth and speed. Therefore RF-based

technologies such as today‟s Wi-Fi are not the optimal

way. In addition, Wi-Fi may not be the most efficient

way to provide new desired capabilities such as

precision indoor positioning and gesture recognition.

Optical wireless technologies, sometimes called visible

light communication (VLC), and more recently referred

to as Li-Fi (Light Fidelity), on the other hand, offer an

entirely new paradigm in wireless technologies in terms

of communication speed, flexibility and usability.

References: http://www.lificonsortium.org/ http://www.telegraph.co.uk/technology/news/9974821/Li-Fi-researchers-claim-speed-breakthrough.html http://purevlc.com/what-is-li-fi/ http://electronicsforu.com/electronicsforu/circuitarchives/view_article.asp?sno=778&title%20=%20Li-Fi%3A+A+New+Paradigm+in+Wireless+Communication&id=12042&article_type=8&b_type=new

Just for Fun!!!

Facts about Engineering, Science and Technology:

220 million tons of old computers and other technological

hardware are trashed in the United States each year.

A Diamond will not dissolve in acid. The only thing that can

destroy it is intense heat.

According to Moore's Law, microchips double in power every

18 to 24 months.

Valdemar Poulsen, a Danish engineer, invented an arc converter

as a generator of continuous-wave radio signals in 1902

As of early 2009, there have been 113 space shuttle flights since

the program began in 1981.

U.S. President Bill Clinton's inauguration in January 1997 was

the first to be webcast.

Tim Berners-Lee coined the phrase “World Wide Web” in 1990.

Near field communication (NFC)

Rejin Shrestha-EE, 3rd year

Near field communication is a form of contactless communication between

devices like Smartphone or tablets. Contactless communication allows a user to

wave the Smartphone over a NFC compatible device to send information without

needing to touch the devices together or go through multiple steps setting up a

simple connection.

For example, Nokia, BlackBerry, Samsung, Sony have used NFC technology to

pair Bluetooth headsets, media players, and speakers with one tap in its NFC-

enabled devices. The same principle can be applied to the configuration of Wi-Fi

networks.

Bluetooth and Wi-Fi seem similar to near field communication on the surface. All

three allow wireless communication and data exchange between digital devices

like Smartphone. Yet near field communication utilizes electromagnetic radio

fields while technologies such as Bluetooth and Wi-Fi focus on radio

transmissions instead

Devices using NFC may be active or passive. A passive device, such as an NFC

tag, contains information that other devices can read but does not read any

information itself. Active devices can read information and send it. An active

NFC device, like a Smartphone, would not only be able to collect information

from NFC tags, but it would also be able to exchange information with other

compatible phones or devices and could even alter the information on the NFC

tag if authorized to make such changes.

Nokia 6131 was the first NFC phone

Samsung Nexus S: First Android NFC phone

IT IS NOT A FUTURE APPLICATION, IT IS AVAILABLE TODAY!! TODAY'S TECH, NOT

TOMORROW'S!!

“Stay hungry. Stay foolish.”

TECH-BRIEF 3 May 16, 2013

SOLAR-PAINT: THE FUTURE OF ENERGY SOURCE |Birendra Suwal -EE 2nd year

The energy demand is increasing every day and so is burning of fossil fuel for energy. This has contributed a lot to Global Warming and

natural calamities. This has forced us to take a fresh look at the clean energy source with the potential to revolutionize the power production.

Our only choice that can meet the inaccessible human appetite for energy is the SUN. Scientists believe solar technology has to become much

cheaper to fulfill the energy requirements and they are hoping NANO Technology will help do that. So they are working on Nano-structures,

Nano-tubes, Nano-particles where NANO means really tiny. A nanometer is one billionth of a meter. They are trying to use these materials to

capture, store and convert sunlight in new ways. This could be so cheap that we can paint our roof and our house with these particles. This

would highly reduce the cost of solar electricity production.

Here is how Nano-paint might work. First we need to roll-out a layer of something to help conduct the electricity, a thin sheet of plastic with

the aluminum coating will do. We also need wire that would ultimately conduct the electricity to the house. Now we are ready for Nano-solar-

paint.

The key ingredient, a compound called titanium-oxide (TiO2) is processed into nano tubes that points toward the sun like blades of grass.

Titanium-oxide (TiO2) is incredibly common and cheap chemical, it‟s in toothpaste also it‟s a pigment in white paint. When photons of

sunlight strikes individual TiO2 atoms, they knock loose electrons and if we put the positively charged clear coating over the paint, the

negatively charged freed electrons start moving to the wires and down to the inverter boxes.

So far the solar paint is being tested in small amount. The Dye based test sample in the lab showed to have 10% efficiency and silicon based

20% efficiency. But even at 10% efficiency solar-paint could produce a whole lot of electricity at low price.

Comparison

Conventional solar cell Cell made from solar paint

Not flexible and heavy

Cannot respond at low light levels

Provides power comparatively at

higher cost

Flexible and very thin

Can even respond at low light levels

Provides power at low cost

Imagine that you have to spend your whole day without mobile,

laptop, iPod, Google, Facebook and other stuffs on Internet, how

hard it would be for someone to do that? Electronic gadgets are

intended for everyday use, most often for entertainment,

communication and office. These products have become such

intrinsic part of our lives that it‟s impossible to imagine a life

without electricity or electronic goods.

The day begins with a digital alarm clock and the word „digital‟

travels with us throughout the day – wherever we go and whatever

we do. These electronic gadgets have already left a huge impact on

our lifestyle; people of all ages are using different types of gadgets.

It is now practically impossible to live life without them.

Managing to-do list, synchronizing contacts, all our activities are

controlled by these gizmos and gadgets.

Mobile phones lie at the center of our life; reminders, to-do‟s,

contacts, emails – everything can be tracked with a latest cell

phone set. Music lovers can buy a mobile phone with good sound

quality, radio and enough memory to store songs. In Japan one

school ordered their students to bring their iPhones along,

according to them they use some technology which recognizes the

phone id to check if the student is present or not. This example

shows how technology is binding with normal human life.

If on any day we forget to take any of these daily used gadgets, we feel

something missing and that one day becomes boring as hell. It proves that we

are so dependent on these gadgets that life without them seems impossible.

So are we becoming over dependent on technology?

Is technology proving to be a Good servant or Bad master?

That is up to you to decide whether you want to be MASTER OF GOOD

SERVANT or SERVANT OF BAD MASTER!

Life without Electronic Gadgets |Rasendra Man Shrestha-EE 2nd Year

Reference

http://anshulbhatia.wordpress.com/2011/02/06/life-without-gadgets/

http://articles.pubarticles.com/life-impossible-without-electronic-goods-

1329206632,689627.html

http://kamaljit-

gillove.blogspot.com/2011/03/life-human-

being-without-electronic.html

http://kamaljitgillove.blogspot.com/2011/03/de

pendence-of-daily-life-on-electronic.html

http://www.freearticlesinc.com/view_article-

id-1051-at-Can%27t-we-live-life-without-the-Electronics-or-Gadgets.html

Did you know???

The longest regularly formed

English word is

Praetertranssubstantiationalisticall

which contains 37 letters.

TECH-BRIEF 4 May 16, 2013

JUST FOR FUN!!!

Electronic Blueprint to Manufacture Artificial

Brain

– Rajeev Bista EE IIIrd Year

Scientists have been dreaming long, about building a computer that would work

like a brain. This is because a brain is far more energy-saving than a computer, it

can learn by itself, and it doesn‟t need any programming. Privatdozent [senior

lecturer] Dr. Andy Thomas from Bielefeld University‟s Faculty of Physics is

experimenting with memristors – electronic micro components that imitate natural

nerves. Thomas and his colleagues proved that they could do this a year ago. They

constructed a memristor that is capable of learning. Andy Thomas is now using his

memristors as key components in a blueprint for an artificial brain.

Memristors are made of fine nanolayers and can be used to connect electric

circuits. For several years now, the memristor has been considered to be the

electronic equivalent of the synapse. *Synapses are, so to speak, the bridges across

which nerve cells (neurons) contact each other. Their connections increase in

strength the more often they are used. Like synapses, memristors learn from

earlier impulses. In their case, these are electrical impulses that (as yet) do not

come from nerve cells but from the electric circuits to which they are connected.

The amount of current a memristor allows to pass depends on how strong the

current was that flowed through it in the past and how long it was exposed to it.

A nanocomponent that is capable of learning: The Bielefeld memristor built into a chip here is 600

times thinner than a human hair.

Andy Thomas explains that because of their similarity to synapses, memristors are

particularly suitable for building an artificial brain – a new generation of

computers. „They allow us to construct extremely energy-efficient and robust

processors that are able to learn by themselves.‟ Based on his own experiments

and research findings from biology and physics, his article is the first to

summarize which principles taken from nature need to be transferred to

technological systems if such a neuromorphic (nerve like) computer is to function.

Such principles are that memristors, just like synapses, have to „note‟ earlier

impulses, and that neurons react to an impulse only when it passes a certain

threshold.

„This is all possible because a memristor can store information more precisely

than the bits on which previous computer processors have been based,‟ says

Thomas. Both a memristor and a bit work with electrical impulses. However, a bit

does not allow any fine adjustment – it can only work with „on‟ and „off‟. In

contrast, a memristor can raise or lower its resistance continuously. „This is how

memristors deliver a basis for the gradual learning and forgetting of an artificial

brain,‟ explains Thomas.

*MEMRISTORS: The memristor was considered the fourth fundamental circuit element

forming a non-linear relationship between electric charge and magnetic flux linkage.

*SYNAPSE: In the nervous system, a synapse is a structure that permits a neuron (or nerve cell)

to pass an electrical or chemical signal to another cell (neural or otherwise).

TECH-BRIEF 5 May 16, 2013

UPS: Basic Working Principle |Amit Bhujel-EE IInd year

“Power cut off! I had lots of tasks yet to be saved!!!” Most of us have faced such situation when there is unexpected power cutoff. In truth,

power sags, surges and outages are not only unavoidable but more than capable of damaging valuable IT equipment and bringing productivity to

a halt. That‟s why planning and deploying a robust power protection solution is absolutely vital. A system is adopted to compensate the power

supply whenever there is power cutoff and to ensure consistent, stable and uninterrupted supply of power and the system is termed as

Uninterrupted Power Supply (UPS). This white paper provides an introductory overview of what a UPS is what kinds of UPS are available and

how they work.

UPS can be broadly classified into three varieties, known as topologies.

Single-conversion systems

In normal operation, these feed incoming utility AC power to IT equipment. If the AC input supply falls out of predefined limits, the UPS

utilizes its inverter to draw current from the battery, and also disconnects the AC input supply to prevent feedback from the inverter to the utility.

The UPS stays on battery power until the AC input returns to normal tolerances or the battery runs out of power, whichever happens first.

Double Conversion Systems

As the name suggests, these devices convert power twice. First, an input

rectifier converts AC power into DC and feeds it to an output inverter.

The output inverter then processes the power back to AC before sending

it onto IT equipment. This double-conversion process isolates critical

loads from raw utility power completely, ensuring that IT equipment

receives only clean, reliable electricity. In normal operation, a double-

conversion UPS continually processes power twice. If the AC input

supply falls out of predefined limits, however, the input rectifier shuts

off and the output inverter begins drawing power from the battery

instead. The UPS continues to utilize battery power until the AC input

returns to normal tolerances or the battery runs out of power, whichever

occurs sooner. In case of a severe overload of the inverter, or a failure of

the rectifier or inverter, the static switch bypass path is turned on

quickly, to support the output loads.

Multi-mode systems

These combine features of both single and double-conversion technologies while providing substantial improvements in both efficiency and

reliability:

Under normal conditions, the system operates in line-interactive mode, saving energy and money while also keeping voltage within safe

tolerances and resolving common anomalies found in utility power.

If AC input power falls outside of preset tolerances for line-interactive mode, the system automatically switches to double-conversion

mode, completely isolating IT equipment from the incoming AC source.

If AC input power falls outside the tolerances of the double-conversion rectifier, or goes out altogether, the UPS uses the battery to keep

supported loads up and running. When the generator comes online, the UPS switches to double-conversion mode until input power

stabilizes. Then it transitions back to high-efficiency line-interactive mode.

Multi-mode UPSs are designed to dynamically strike an ideal balance between efficiency and protection. Under normal conditions, they provide

maximum efficiency. When problems occur, however, they automatically sacrifice some efficiency to deliver maximum levels of protection. The

end result is that data centers can save tens of thousands a year on energy without compromising data center performance or reliability.

Conclusion

A well-built power protection solution, featuring high-quality, highly efficient UPS hardware, can help keep your business applications

available, your power costs manageable and your data safe. By familiarizing themselves with the basics of what a UPS does and how to choose

the right one for their needs, data center operators can ensure that mission-critical systems always have the clean, reliable electricity they need to

drive long-term success.

Reference: “UPS Basics” EATON Corporation, 2011

PowerInterface

LoadLine

I n v e r t e r

BatteryCharger

BatteryBank

MainLine

Operation with Main LineOperation with Backup Charge

Figure: Single Conversion UPS

JUST FOR FUN!!!

TECH-BRIEF 6 May 16, 2013

Well I am sure some of you are reading this article to

know which mobile shall be the best (if you are

planning to buy one). And many of you are checking

the list to know if your cell phone is in the list too.

Wish you luck!

Mobile phones are the hottest kind of tech. No one

can have just one, we love to update. They are also the

gadgets that we are most willing to spend our hard

earned cash (or may be our parent‟s).These days smart

phones have become our best friends. Smart phones

work as our personal computers, high resolution

cameras, television, radio, mp3 player, guidebooks,

and everything we need. Well here is a little about

some mobile phones worth a look.

Number 1: HTC One

Looks great and has wonderful features. Has

rightfully nailed the 1st position

First

released:

March 2013

Weight:

143 grams (5 oz.)

O.S:

Android 4.1.2

Camera: 14 megapixel, 2.0 mp camera with auto

focus, "UltraPixel"image sensor, smart

LED flash, optical image

stabilization.(font camera: 2.1 MP)

Memory

2 GB LPDDR2 RAM

Top 5 Smart Phone 2013 -Compiled by Prakriti Rajbhandari EE-III

rd Yr

Number 2: Samsung Galaxy S4

Whether it's a powerful camera, a brilliant screen, a long-lasting battery or just a

fluid experience, there's everything you could want in a smartphone right here.

FEATURES:

First

released:

April 2013

Weight:

130 grams (4.6 oz.)

O.S:

Android 4.2.2 jelly bean

Camera: 13 megapixels 1080p Full HD Video recording, Auto

focus, Touch to focus, Digital image stabilization, Face

detection, Smile detection, Exposure compensation.

(front camera: 2 megapixels 1080p, HD Video Recording )

Memory:

2 GB LPDDR3 RAM

Number 3: Sony Xperia Z

I would call it a handsome phone. Its video, where the phone has been covered by

hot chocolate to check its endurance is in hype. It deserves its rank.

FEATURES: First

released:

February 9, 2013

Weight:

146 grams (5.15 oz.)

O.S:

Android 4.1 jelly bean

Camera: 13.1 megapixels (1080p)

(front camera: 2.2 megapixels ,1080p video recording)

Memory:

2GB RAM

Did you know!!!!!

Solar Impulse, an airplane traveling across the United States using only solar power is Phoenix ,after reaching Arizona from

California.The aircraft is capable of flying at night as well as in daytime.Solar Impulse's "wingspan is longer than a 747 Boeing, but

the entire plane weighs less than a car," as NPR's Steve Henn reported.The first leg of the trip was piloted by Bertrand Piccard; his

co-founder in the venture, André Borschberg, will also pilot the plane during its American trip.It is powered with 12000 solar cells

capable of achieving 49 km/hr at the elevation of 27000ft.

TECH-BRIEF 7 May 16, 2013

Number 4: iPhone 5

It comes as a shock to all the iPhone lovers. Smart

phones with better services at comparatively much

lower prices have made it difficult for iPhone to

maintain its rank.

FEATURES: First

released:

March 2013 (available only in particular

countries)

Weight:

112 grams (2.95 oz.)

O.S:

i.o.s 6.1.4

Camera: 8 megapixels, HD Video(1080p)

(front camera: 1.2 megapixels ,720pHD

video recording)

Memory:

1GB LPDDR2-1066 RAM

Number 5: Google Nexus 4

Google and LG have worked together to bring to market a fantastic offering, one that even Apple fans can't help but coo over when they hear the price. This is the best Nexus handset so far by a long shot. FEATURES: First

released:

November 13 2012

Weight:

139 grams (4.9 oz.)

O.S:

Android 4.2.2 jelly bean

Camera: 8 megapixels with led flash

(front camera: 1.3 MP)

Memory:

2 GB RAM

These were the top 5 smart phones of 2013, with their features.

Other top phones on the list:

Number 6: Samsung Galaxy Note 2

Number 7: Samsung Galaxy S3 Number 8: Nokia Lumia 520

Number 9: HTC One S

Number 10: Nokia Lumia 920

References:

http://reviews.cnet.com/best-android-phones/

http://www.techradar.com

JUST FOR FUN !!!

TECH-BRIEF 8 May 16, 2013

Amazing Electrical world!!!!

World’s largest thermal solar plant (377MW) in Mojave

The Three Gorges Dam is a hydroelectric dam that spans the Yangtze River by the town of Sandouping, located in Yiling

District, Yichang, Hubei province, China. The Three Gorges Dam is the world's largest power station in terms of installed

capacity (22,500 MW).