CAD Conference Exhibition CAD’12 Volume · International CAD Conference and Exhibition, Final...

International CAD Conference and Exhibition

Final Program – CAD’12 Volume 9

CAD’12 JUNE 11‐14, 2012MARRIOTT GATEWAY ON THE FALLS HOTEL

NIAGARA FALLS, CANADA

www.cadconferences.com

International CAD Conference and Exhibition, Final Program CAD’12 Volume 9 2 of 113

International CAD Conference and Exhibition Final Program

ISSN 2291‐1987

CAD’12 Volume 9

www.cadconferences.com/Program/CAD12Program.html

Copyright © 2012

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Presentation Abstracts

Full length manuscripts for many of the presentations will be archived in the journal

Computer Aided Design & Applications (www.cadanda.com)

When available, the web link to the journal manuscript will be linked using a red underline as follows

Paper 24

Title:

Interactive Inverse 3D Modeling

www.cadanda.com

http://www.cadanda.com/CADandA_9_6_881-900.html


Paper 2

Title:

Dimensional Accuracy and Surface Quality Assessment of FDM and ZPrinter Models

Authors:

Hassan Iqbal1, Anwar K Sheikh2 , Mohudin Ahmed3, M.Younas4 1King Fahd University of Petroleum and Minerals, [email protected] 2King Fahd University of Petroleum and Minerals, [email protected] 3King Fahd University of Petroleum and Minerals, [email protected] 4King Fahd University of Petroleum and Minerals, [email protected]

Abstract:

Z‐Printer and FDM are two important types of additive rapid prototyping systems. Models made on both

systems have different properties which make them viable for different prototyping needs depending on

strength, surface finish, dimensional accuracy and cost. The purpose of this paper is to study the

dimensional accuracy and surface assessment of models made of both systems. FDM TITAN and Z‐450

ZPrinter were used to fabricate the test models. The dimensional accuracy and surface finish was

analyzed by using laser scanner and surface roughness tester respectively. Based on this study the

capability of the both systems will be assessed to meet the rapid prototyping quality needs on the bases

of dimensional accuracy and surface finish requirements for the needed application. FDM is usually used

for the models suitable to check fitment and operational characteristics and functionality of the part,

as well as to make pattern models for making sand or silicon molds, whereas ZPrinters are known

primarily for visualization ,concept verification or product marketing purposes.. However in this paper

the feasibility was studied of model manufacturing by using FDM as well as Z‐Printer based on

dimensional accuracy and surface finish as a key factor, for any application where any of these models

can be used.

Keywords:

Rapid Prototyping, FDM, Z‐Printer, Surface Finish, Dimensional Accuracy, Process Optimization, Surface

Measurement.


Paper 3

Title:

Application of NX Knowledge Fusion module for the Design Automation of an Automotive Painting

Defects Inspection Tunnel

Authors:

Bernal Z. Fabio A.1, Rojo V. Alejandro2 and Tornero M. Josep3 1Tecnológico de Monterrey, [email protected] 2Tecnológico de Monterrey, [email protected] 3Universidad Politécnica de Valencia, [email protected]

Abstract:

This article shows the application of Knowledge Based Engineering (KBE) methodology for the design

automation of the structure of an automotive painting defects inspection tunnel. A previous work

reached the design automation through the data transferring from Spreadsheets to Siemens NX CAD

software using applications programmed with Visual Basic. With the application of KBE, it was possible

to control the geometrical features of every part in the tunnel, to properly manage the component

addition to the assembly and to reach a direct interaction between the designer and the CAD tunnel

model in a new and more insightful manner. The presented work was developed through Knowledge

Fusion (KF), a Siemens NX module which is based in Knowledge Based Engineering (KBE).

Keywords:

KBE, knowledge fusion, CAD, design automation



Paper 5

Title:

A Hybrid Redesign Strategy to Derive Load‐Adaptive Parts

Authors:

Uwe Klemme1 and Prof. Peter Köhler2 1University of Duisburg‐Essen (Germany), uwe.klemme@uni‐due.de 2University of Duisburg‐Essen (Germany), peter.köhler@uni‐due.de

Abstract:

The meaning of simulation of virtual prototypes has become more and more important over the past

years. Corresponding to this is the necessity to manipulate the CAD‐parts which represent the basis of

those simulations. This article deals with methods to handle virtual models in theory and praxis within

the context of a simulation process. In detail an approach for a workflow is presented that enables one

to make use of a deformed part in the CAD‐environment after successful structural simulation. The

advantage of the utilization of such native CAD data which fulfill specific needs with regard to the

applied load situation is based on the still precise and parametric definition of the geometry, as there is

no approximation through smoothing or similar necessary. One pre‐condition is the use of an efficient

CAD software with the ability to create hybrid models. During realization of the approach there are

issues of coding and software‐interfaces to be taken into account as well as a proper modeling strategy

within the context of CAD. Therefore one of the main aspects will be to create a CAD‐model in a way

that enables loss‐free implementation of external data. The approach also increases the available

degrees‐of‐freedom for geometry‐manipulation in contrast to sizing‐ and shape‐optimization. In further

steps this method is mainly utilized to create load‐adaptive parts in an iterative optimization process.

Keywords:

CAD, CAO, comprehensive adaptivity, virtual redesign, interoperability



Paper 6

Title:

Computing Rotation Minimizing Frames using Quaternions

Authors:

David Yoon1, Mark Narduzzi2 and Jie Shen3

1University of Michigan ‐ Dearborn, [email protected] 2University of Michigan ‐ Dearborn, [email protected] 3University of Michigan ‐ Dearborn, [email protected]

Abstract:

Frenet Frames have been employed as local frames along a trajectory. However, they behave poorly

around inflection points of the path. To remedy this, we propose to compute rotation minimizing frames

(RMF) using quaternions.

Keywords:

3D curves, Frenet Frames, Rotation Minimizing Frames



Paper 7

Title:

Luminance Contrast as Depth Cue: Investigation and Design Applications

Authors:

Nan‐Ching Tai1 and Mehlika Inanici2

1Tamkang University, [email protected] 2University of Washington, [email protected]

Abstract:

It is known that contrast can be an effective depth cue on planar displays. However, previous studies do

not provide enough information on the impact of luminance contrast and luminance distribution

patterns on perceived distances in three dimensional built spaces. This research investigates the role of

luminance contrast and luminance distribution patterns on space perception of three‐dimensional

layouts. Three experiments were conducted to study the impact of the following parameters on depth

perception: 1) investigation of different lighting apertures, 2) lighting distribution patterns, and 3)

luminance contrast as a depth cue. It is concluded that the luminance contrast of a target against its

surround is an effective depth cue that can increase or decrease the perceived distance of a visual target

in a built space. The application of this depth cue is demonstrated through an architectural design

example.

Keywords:

Space Perception, Depth Cue, Luminance Contrast, Psychophysical Experiments, High Dynamic Range

Imagery



Paper 8

Title:

GPU Based Evaluation and LOD Rendering of NURBS Surfaces

Authors:

Tan Dunming1,2, Zhao Gang1 and Lu Hu3

1State Key Laboratory of Virtual Reality Technology and Systems, Beihang University,

[email protected] 2The First Aeronautical Institute of PLA Air Force, [email protected] 3Shanghai Aircraft Manufacturing CO., Ltd, [email protected]

Abstract:

This paper proposes a new GPU method for the evaluation and LOD (Level of Detail) rendering of NURBS

surfaces. Compared with the existing evaluation method of basis function, the approach simplifies the

process by just one‐pass and saves the graphics memory with only one texture array. The wavelet based

LOD rendering method also saves the time to re‐evaluate and re‐transfer the data for rendering.

Keywords:

GPU, NURBS, De Boor's algorithm, LOD, wavelet



Paper 9

Title:

The Evolutes of Log‐Aesthetic Planar Curves and the Drawable Boundaries of the Curve Segments

Authors:

Norimasa Yoshida1, Takafumi Saito2

1Nihon University, [email protected] 2Tokyo University of Agriculture and Technology, [email protected]

Abstract:

This paper investigates the two characteristics of log‐aesthetic curves. We first show that the evolutes of

log‐aesthetic curves are also log‐aesthetic curves. We provide a proof that the evolute of a log‐aesthetic

curve with the shape parameter ・ is a log‐aesthetic curve with the shape parameter 1/ 2 . Then,

we present a method for drawing the theoretical drawable boundaries of log‐aesthetic curve segments

with 0 or 1 . We compare the theoretical drawable boundaries with the experimental drawable

regions and show that they agree well except when is close to 0 .

Keywords:

log‐aesthetic planar curves, evolute, drawble region



Paper 10

Title:

Optimized Control of Indoor Environmental Health ‐ Example of the Fu‐An Memorial Building

Authors:

Shang‐Yuan Chen1, Jui‐Ting Huang2, Show‐Lin Wen3, Ming‐Whei Feng4

1Feng Chia University, [email protected] 2Feng Chia University, Smart Network System Institute, [email protected] 3Chinese Culture University, [email protected] 4Smart Network System Institute, [email protected]

Abstract:

This study proposes the establishment of an environmental health information management platform

providing residential users a comfortable, healthy indoor environment. Taking the Fu‐An Memorial

Building, as an example, the design of the control logic algorithm ensures that the environmental health

information management platform can simultaneously: (1) provide a healthy indoor environment and

(2) realize optimized control mechanisms and methods minimizing the energy consumption of the

building's environmental control equipment. Because of this, the Fu‐An Memorial Building uses (1) PMV

thermal comfort sensors, (2) energy‐conserving environmental controls, and (3) natural ventilation to

regulate the building's interior microclimate, realizing an energy‐saving, environmentally‐friendly, smart

building. The study and building construction work revealed that the next stage should include:

(1) development of an expert system to control the health environment, (2) establishment of an

information processor learning mechanism, and (3) development of adaptive logic control technology.

Keywords:

optimized control, building environmental control system, environmental health information

management platform



Paper 11

Title:

Conceptual Design of Hemp Fibre Production Lines in Virtual Environments

Authors:

Jinke Xu1, Qingjin Peng2 and Ying Chen3

1McGill University, [email protected] 2University of Manitoba, [email protected] 3University of Manitoba, [email protected]

Abstract:

Increasing demand for hemp fibre requires sustainable manufacturing methods to produce the fibre in

high quality efficiently. The existing hemp fibre production lines are inefficient with the high energy

consumption. This paper introduces the conceptual design of hemp fibre production lines. The

conceptual design and evaluation are conducted in virtual environments. A conceptual search and

evolution method is described for the design of two types of the fibre production lines. Virtual

environments are built to evaluate prototypes of the conceptual design and to simulate operations of

the proposed production lines. Design visualization and concept evolution are achieved in the virtual

environment. It is proved that the proposed design has the better performance in terms of cost, product

quality and energy efficiency.

Keywords:

Conceptual design, Hemp fibre production, Virtual environments



Paper 13

Title:

Data Compression Method for Trimmed Surfaces Based on Surface Fitting with Maintaining 1G

Continuity with Adjacent Surfaces

Authors:

Yuta Muraki1, Katsutsugu Matsuyama2, Kouichi Konno3 and Yoshimasa Tokuyama4

1Iwate University, muraki@iwate‐u.ac.jp 2Iwate University, [email protected]‐u.ac.jp 3Iwate University, [email protected]‐u.ac.jp 4Tokyo Polytechnic University, [email protected]‐kougei.ac.jp

Abstract:

Trimmed surfaces are one of the versatile shape representations. When 3D data is put into circulation

on the Internet, data size reduction for trimmed surfaces is an important issue in digital engineering. In

this paper, we propose a data compression method based on surface fitting method. Our method

enables efficient surface data compression by using the surface fitting method. In our method, the

surface fitting method is applied to a closed region surrounded by the boundary edges of a 3D shape

model. With the approximation method that uses boundary curves and sample points based on a

tangent plane at the boundary edges, the surface fitting method can also be applied to shapes with

holes or concave shapes. In order to maintain 1G continuity with adjacent surfaces, the cross boundary

derivatives obtained by the surface interpolation method are applied to the connection section with

adjacent surfaces. When a surface is generated in good accuracy, the original surface element can be

deleted and data size can be drastically reduced. The deleted surface element can be reconstructed

from the boundary edges using our method.

Keywords:

Trimmed Surface, Surface Fitting, Data Compression, 1G continuity, Notch Shape



Paper 14

Title:

Design of the Tolerance Ring in the Actuator Arm of a Hard Disk Drive Using Finite Element Analysis

Authors:

Somkid Suthaweesub1 and Arbtip Dheeravongkit2

1King Mongkut’s University of Technology Thonburi, Thailand, [email protected] 2King Mongkut’s University of Technology Thonburi, Thailand, [email protected]

Abstract:

This paper presents conceptual designs of the hard disk drive's tolerance ring in order to reduce the

installation force during the assembly process of the actuator arm and to decrease the total deformation

of the tolerance ring, while maintaining the natural frequency within the specification range. In this

research, the finite element analysis is employed to compare and analyze the installation forces, total

deformations of tolerance ring, and natural frequencies of Actuator Pivot Flex Assembly (APFA). Around

its cylindrical body, the tolerance ring consists of several waves, which provide stiffness for the APFA

assembly to resist the axial rocking motion of the actuator arm. The idea is to decrease the contact

surface area between the waves and the e‐block by smoothing the contacting surface of the waves

along the installation direction, while keeping enough friction to resist the axial rocking motion. This

research examines five designs of tolerance ring's wave, including the vertical and horizontal curve

designs, the symmetric and asymmetric wave designs, and the alternating flat‐curve design. The finite

element analysis results show that the concept of the horizontal curve design is better than the vertical

curve design, since it effectively decreases both the installation force and the total deformation of the

tolerance ring, while the natural frequency of the pivot butterfly mode remains within the specification

range. However, the alternating flat‐curve design can keep the installation force and the natural

frequency closer to the mid values of the specification range than other designs.

Keywords:

hard disk drive, finite element analysis, tolerance ring, mechanical vibration, natural frequency


Paper 16

Title:

Advances and Prospects of Digital Metrology

Authors:

Jie Shen1 and David Yoon2

1University of Michigan‐Dearborn, [email protected] 2University of Michigan‐Dearborn, [email protected]

Abstract:

In this paper, the authors first summarize recent advances in digital metrology at the Virtual Engineering

Laboratory, the University of Michigan – Dearborn. Different algorithms of surface denoising of laser

scanning and computed tomography are then briefly discussed. Last, some challenges of digital

metrology are provided for supporting high‐precision digital manufacturing and industrial inspection.

Keywords:

Metrology, Reverse Engineering, Laser Sensor, Noise, Computed Tomography



Paper 17

Title:

Multi‐Chip Power Module Fast Thermal Modeling for Layout Optimization

Authors:

Brett W. Shook1, Zihao Gong2, Yongfeng Feng3, A. Matthew Francis4, and H. Alan Mantooth5

1University of Arkansas, [email protected] 2University of Arkansas, [email protected] 3University of Arkansas, [email protected] 4University of Arkansas, [email protected] 5University of Arkansas, [email protected]

Abstract:

This paper proposes a method for fast thermal modeling of Multi‐Chip Power Modules (MCPMs) for use

in layout optimization. MCPMs integrate multiple high power semiconductor devices into a single

package and allow for increased power densities and efficiencies critical for next generation alternative

energy systems. In a typical MCPM layout, the design is modified iteratively to search for best electrical,

thermal, and electromagnetic performance. In order to speed up design optimization, a novel thermal

model is developed which can approximate thermal performance of a module under modifications of

metal trace layout and power device positioning and quantity. Particle Swarm Optimization is chosen to

perform the layout optimization process and is briefly compared against other optimization techniques.

Keywords:

Multi‐Chip Power Modules, Thermal Modeling, Layout Optimization



Paper 19

Title:

A Model Based Enterprise Approach in Electronics Manufacturing

Authors:

Ibrahim T. Ozbolat 1, Amer Dababneh2, Omer Elgaali3, Yahui Zhang4, Timothy Marler5 and Steven Turek6

1The University of Iowa, ibrahim‐[email protected] 2The University of Iowa, amer‐[email protected] 3The University of Iowa, omer‐[email protected] 4The University of Iowa, yahui‐[email protected] 5The University of Iowa, [email protected] 6Air Force Research Laboratory, [email protected]

Abstract:

Electromagnetic compatibility and overheating are two key issues in printed circuit board (PCB)

manufacturing. Due to design and manufacturing limitations, the Department of Defense (DoD)

suppliers put tremendous efforts on testing physical prototypes of PCBs. In this work, we developed a

model‐based interactive and 3D environment, the predictive environment for visualization of

electromechanical virtual validation (PREVIEW), to test and analyze the virtual performance of PCBs,

which aids designers assessing manufacturability of PCBs virtually prior to developing a physical

prototype. Firstly, a thermal simulation module is developed and integrated into PREVIEW to analyze

thermal performance of PCBs. Secondly, electromagnetic compatibility is visualized through simulation

of 3D electromagnetic field and noise emission.

Keywords:

electronics manufacturing, printed circuit Boards, model based enterprise



Paper 20

Title:

Concave hull of a set of freeform closed surfaces in 3R

Authors:

A. V. Vishwanath1 and M. Ramanathan2

1Indian Institute of Technology Madras, [email protected] 2Indian Institute of Technology Madras, [email protected]

Abstract:

Bounding hulls, such as convex hulls, have been shown to be useful in many application areas. ‐hull, a

generalization of convex hull, has been predominantly employed in reconstruction. Other hulls such as

concave hull, which generates non‐convex polygons poly hull, r ‐shape and s ‐shape etc. have also been

shown to be useful. Most algorithms for bounding hulls deal with point‐set as input. Recently, we

approached the question of bounding hull to a set of close planar freeform curves and proposed an

algorithm for concave hull by defining it (definition was lacking even for a point‐set). In this paper, we

extend it to concave hull of a set of freeform closed surfaces in 3R of genus 0 . Surfaces used are

represented as NURBS (non‐uniform rational B‐splines). The concept of concave hull is then extended

for genus 0 and showed that the hull will consists of lower dimensional elements and topological

disks. Based on this observation, a conjecture is proposed for elements in the concave hull of freeform

closed objects in n dimensions.

Keywords:

concave hull, enclosing surface, region occupied, convex hull, freeform surfaces



Paper 23

Title:

A Robust and Centered Curve Skeleton Extraction from 3D Point Cloud

Authors:

Vanna Sam1, Hiroaki Kawata2 and Takashi Kanai3

1The University of Tokyo, [email protected]‐tokyo.ac.jp 2The University of Tokyo, [email protected]‐tokyo.ac.jp 3The University of Tokyo, [email protected]‐tokyo.ac.jp

Abstract:

A curve skeleton of a 3D object is one of the most important structures of the object, which is extremely

useful for many computer graphics applications involving in shape analysis. Much research has focused

on volumetric and polygonal mesh models. However, only a few have been paid attention to point cloud

and suffered from several limitations such as connectivity or inside‐shape information requirements,

difficulty to compute junction nodes, or inappropriate parameter tuning. To resolve these problems, we

propose an effective algorithm for extracting a robust and centered curve skeleton from point cloud.

The process starts from estimating centers of antipodes of a point cloud, so called skeletal candidates,

which are fundamentally inside the shape; but scattered. We thus filter and shrink them to create less‐

noisy skeletal candidates before applying one‐dimensional Moving Least Squares (MLS) to build a thin

point cloud. The latter is then down sampled to sparse skeletal nodes. With recent nodes, it is possible

to create a smooth curve skeleton; but distorted due to shrinking and thinning (MLS) processes. We thus

utilize cross‐section plane technique and least squares ellipse fitting to relocate skeletal nodes to create

a centered curve skeleton. The algorithm is validated on many complex models ranging from cylindrical

to planar ones, and from clean to noisy and incomplete data. We show that the extracted curve skeleton

is robust to noises and under centeredness property.

Keywords:

curve skeleton, point cloud, antipode, regression line, ellipse fitting



Paper 24

Title:

Interactive Inverse 3D Modeling

Authors:

James Andrews1, Hailin Jin2 and Carlo Séquin3

1University of California, Berkeley, [email protected] 2Adobe, [email protected] 3University of California, Berkeley, [email protected]

Abstract:

“Interactive Inverse 3D Modeling” is a user‐guided approach to shape construction and redesign that

extracts well‐structured, parameterized, procedural descriptions from unstructured, hierarchically flat

input data, such as point clouds, boundary representation meshes, or even multiple pictorial views of a

given inspirational prototype. This approach combines traditional “forward” 3D modeling tools with a

system of user‐guided extraction modules and optimization routines. With a few cursor strokes users

can express their preferences of the type of modeling primitives to be used in a particular area of the

given prototype to be approximated, and they can also select the degree of parameterization associated

with each modeling routine. The results are then pliable, structured descriptions that are well suited to

implement the particular design modifications intended by the user.

Keywords:

reverse engineering, shape redesign, parameterized procedural modeling, interactive structure

extraction, generalized sweeps



Paper 25

Title:

Variational Formulation of the Log‐Aesthetic Surface and Development of Discrete Surface Filters

Authors:

Kenjiro T. Miura1, Ryo Shirahata2, Shin’ichi Agari3, Shin Usuki4 and R.U. Gobithaasan5

1Shizuoka University, [email protected] 2Shizuoka University, [email protected] 3Shizuoka University, [email protected] 4Shizuoka University, [email protected] 5University Malaysia Terengganu, [email protected]

Abstract:

Log‐aesthetic curves include the logarithmic (equiangular) spiral, clothoid, and involute curves. Although

most of these are expressed only by an integral form of the tangent vector, it is possible to interactively

generate and deform them, and they are expected to be utilized in industrial and graphical design. The

discrete log‐aesthetic filter based on the formulation of the log‐aesthetic curve has successfully been

introduced to avoid strong constraints on the designer's activity, to allow free design, and to embed the

properties of the log‐aesthetic curves for complicated shapes with both increasing and decreasing

curvature. In this paper, to define the log‐aesthetic surface and develop surface filters based on its

formulation, we first reformulate the log‐aesthetic curve with variational principles. Then, we propose

several new functionals to be minimized for free‐form surfaces and define the log‐aesthetic surface.

Furthermore, we propose new discrete surface filters based on the log‐aesthetic surface formulation.

Keywords:

log‐aesthetic surface, log‐aesthetic curve, variational principle, digital filter, discrete curve and surface.



Paper 26

Title:

Grain Generation Method for Large Die Data Using the Out‐of‐Core Method

Authors:

Cam Nguyen Tang1, Daijiro Uzuyama2, Kenjiro T. Miura3, Shin Usuki4 and Mamoru Kikuta5

1Shizuoka University, [email protected] 2Shizuoka University, [email protected] 3Shizuoka University, [email protected] 3Shizuoka University, [email protected] 5Calsonic Kansei Corp., KIKUTA‐M@ck‐mail.com

Abstract:

The surfaces of automobile interior parts have geometrically microfabricated textures, which are called

“grain textures.” The purpose of our research is to mill dies with grain by use of digital data. We

generate microfabricated geometric data from a large CAD model of a die with the out‐of‐core method,

texture synthesis, and displacement mapping. With these geometric data, the die with grain can be

manufactured by milling or laser machining

Keywords:

digital grain generation, out‐of‐core, s‐patch



Paper 27

Title:

Mesh Segmentation and Surface Reconstruction of Automotive Panels

Authors:

Chun‐Fong You1 ,Yu‐Yu Lin2, Kai‐Wei Tzeng3, Kun‐Yu Liu4

1Department of ME, National Taiwan University, [email protected] 2Department of ME, National Taiwan University, [email protected] 3Department of ME, National Taiwan University, [email protected] 4Department of ME, National Taiwan University, [email protected]

Abstract:

The after‐market services of automotive industries are incapable of obtaining automotive original panel

designs, explaining why automotive parts are often developed by reverse construction of sheet metal

surfaces. These processes depend entirely on manual trial and error methods. Without systematic

reconstruction methods, quality of the surface varies from individual to individual. Additionally, labor‐

intensive processes have lost their market competitiveness. Therefore, this work presents an semi‐

automatic surface reconstruction scheme, based on the mesh model of automotive panels. Following

calculation of the differential geometric properties, feature point retraction, region growth, and surface

fitting, the results of hood and fender verification demonstrate the feasibility of the proposed surface

reconstruction method. Based on the rule of quadrilateral surface, this work also develops a set of rules

applicable for convex polygon mesh surface reconstruction to increase the applicability of surface fitting.

The proposed methods allow for a systematic and automated construction of the auto parts surface,

thus shortening the manufacturing time.

Keywords:

Auto body parts, Mesh segmentation, Surface reconstruction


Paper 28

Title:

On Incorporating FEM Results in Selective Laser Sintering to Achieve Customized Material Properties

Authors:

Prashant K. Jain1, Pulak M. Pandey2

1PDPM Indian Institute of Information Technology, [email protected]

2Indian Institute of Technology Delhi, [email protected]

Abstract:

This article presents a novel computational method to incorporate stress analysis results by subdividing

a solid model into various subparts and subsequent fabrication of the part using selective laser sintering

process. Stress analysis of a tensile specimen part is carried out in ANSYS software, nodal stress

developed at all the nodal points is calculated and grouped as per stress values. These points are used to

write CLI file. A MATLAB program has been developed for writing CLI files for various sub‐parts based on

the stress analysis. All subdivided solid models are fabricated together by using selective laser sintering

process with parameters assigned as per their stress values. As mechanical properties are varying with

process parameters and hence fabricated part will have customized mechanical properties for different

regions. This paper discusses various issues in implementation and current limitations of the proposed

methodology. Future direction to achieve this for the free form shapes has also been discussed.

Keywords:

Selective Laser Sintering, customized material properties, FEA


Paper 29

Title:

Extended Axiomatic Design and Computational Support to Design for Aesthetics

Authors:

Sitaram Soni1, Pritee Khanna2, Puneet Tandon3

1Research Scholar, PDPM IIITDM, Jabalpur INDIA, [email protected] 2Assoc. Professor, PDPM IIITDM, Jabalpur INDIA, [email protected] 3Professor, PDPM IIITDM, Jabalpur INDIA, [email protected]

Abstract:

The research describes the extension of the Axiomatic Design model to incorporate the aesthetic design

as the customer requirement. It also proposes a computational model to support the formalization of

aesthetic design in industrial products. The methodology takes into account the cognition process during

the design generation and captures this behavior in a group theoretic structure. This approach leads to

application of Axiomatic Design paradigm to the domain of the aesthetics. The proposed framework is

implemented and validated by taking a design case of the consumer products.

Keywords:

aesthetics, knowledge support, generative shape description, axiomatic design



Paper 30

Title:

Optimization of Medical CT Data with High Precision

Authors:

Jing Chi1 and Caiming Zhang2

1Shandong University of Finance and Economics, Ji'nan, China, [email protected] 2Shandong University of Finance and Economics, Ji'nan, China, [email protected]

Abstract:

The precision of medical CT data has an important effect on the CT image reconstruction precision. In

this paper, we present a novel approach for optimizing the raw CT data acquired by scanner. The

approach can effectively improve the raw CT data precision, and consequently, improve the

reconstruction precision. The new approach is based on the fact that the raw CT data can be regarded as

the area samples of human density, and the point samples are more accurate than the area samples.

The new approach transforms the raw area samples to more accurate point samples to improve the CT

data precision by three steps: 1) establish the mapping relationship between area samples and point

samples; 2) Segment the raw CT slice into different regions based on the human tissue feature; 3) in

each segmented region, construct quadric spline fitting equation with the mapping relationship to

transform the area samples to more accurate point samples. Experiments show that the image

reconstruction with the new data optimized by our method has more details and fewer artifacts.

Keywords:

Computerized tomography, Precision optimization, Quadric spline



Paper 31

Title:

A Projection Operator for Representing Sharp Features using Visibility

Authors:

Hiroaki Kawata1 and Takashi Kanai2

1The University of Tokyo, [email protected]‐tokyo.ac.jp 2The University of Tokyo, [email protected]‐tokyo.ac.jp

Abstract:

We propose a projection operator for point sets without normal vector information. Based on the

visibility of points, it is possible to represent sharp features when points are projected on the surface

without normal vector information. Our method is based on the Moving Least‐Square Surface projection

operator. Visibility computation is utilized to avoid average computation of points near sharp features

when selecting points, in which visibility information is computed before starting the projection for

selecting point clouds of one side. We also demonstrate the effectiveness of our visibility approach

through several experiments.

Keywords:

point‐based, projection, sharp feature



Paper 32

Title:

CAD Based Geometric and Force Modeling of Single Point Form‐Cutting Tools

Authors:

K. Sambhav1, P. Tandon2, S.G. Dhande3

1Indian Institute of Technology, Kanpur, India, [email protected] 2PDPM Indian Institute of Information Technology, Jabalpur, India, [email protected] 3Indian Institute of Technology, Kanpur, India, [email protected]

Abstract:

The paper models Single Point Cutting Tools (SPCTs) with free‐form rake and flank surfaces for geometry

and cutting forces using CAD. The geometric profile of the rake and flank surfaces has been modeled

using NURBS where the control points can be arbitrarily chosen and interactively modified to obtain the

desired cutting angles along the cutting edge. Such a model can be employed to design form‐cutting

tools with optimum profile. The geometric model is used to calculate the rake and flank angles in the

prevalent nomenclatures such as ASA, ORS and NRS by obtaining projections to the normal along the

cutting edge on the chosen planes. The angles are then used to predict the cutting and thrust forces

using a mechanistic equation for HSS tool and MS work‐material combination. To validate the results, an

HSS tool is ground arbitrarily and the points on the cutting edge and rake face are captured. The control

points are derived and the model is fitted to generate the geometry of the tool. Experiments are

conducted for different machining conditions and the theoretical and experimental results are

compared. The results show a good correlation with the prediction.

Keywords:

Single point cutting tool, free‐form, NURBS, mechanistic model



Paper 33

Title:

Designing Natural‐Tooth‐Shaped Dental Implants based on Soft‐Kill Option Optimization

Authors:

Yongki Yoon1, Xiaoyan Sun2, Jen‐Kuang Huang3, Gene Hou4, Krzysztof Rechowicz5, Frederic D. McKenzie6

1Old Dominion University, VA, USA, [email protected] 2Old Dominion University, VA, USA, [email protected] 3Old Dominion University, VA, USA, [email protected] 4Old Dominion University, VA, USA, [email protected] 5Old Dominion University, VA, USA, [email protected] 6Old Dominion University, VA, USA, [email protected]

Abstract:

This paper presents the refinement and optimization of three‐dimensional (3D) dental implants with the

complex root shapes of natural teeth. These root shapes are too complex to be drilled manually like

current commercial implants and so are designed to be conducive to robotic drilling utilizing milling

algorithms. Due to the existence of sharp curvatures and undercuts, anatomically correct models must

be refined for 3D robotic milling and these refined shapes must be shown to be optimized for load

bearing. Refinement of the anatomically‐correct natural tooth‐shaped models for robotic milling was

accomplished using Computer‐Aided‐Design (CAD) tools for smoothing the sharp curvatures and

undercuts. The load bearing optimization algorithm is based on the Soft‐Kill Option (SKO) method, and

the geometries are represented using non‐uniform rational B‐spline (NURBS) curves and surfaces. Based

on these methods, we present optimized single and double root‐shaped dental implants for use with

robotic site preparation.

Keywords:

mesh, dental implants, finite element analysis, shape optimization



Paper 34

Title:

Evaluation of Fatigue for a Pectus Bar Removal Surgical Tool Design for a Safe Clinical Practice Use

Setting

Authors:

Krzysztof J. Rechowicz1, Frederic D. McKenzie2, Sebastian Y. Bawab3 and Robert Obermeyer4

1Old Dominion University, [email protected] 2Old Dominion University, [email protected] 3Old Dominion University, [email protected] 4Children's Hospital of The King's Daughters, [email protected]

Abstract:

The Nuss procedure is a minimally invasive procedure for the correction of pectus excavatum ‐ a chest

wall deformity which results in the placement of a metal bar inside the chest cavity. The bar is removed

after approximately two years. Surgeons report that the currently available tools for the extraction of

the bar are frequently slow and suboptimal. Previously, we had proposed a novel design of the tool

which showed deficiencies when experimentally tested. Then, with the aid of CAD and finite element

analysis, modifications to the original design were adopted to drastically increase the factor of safety.

However, there is a need to determine whether the effects from repetitive loading will affect the

performance of the tool over a long duration and to investigate the accumulation of damage and, hence,

fatigue. In this paper, repetitive loading and fatigue analysis are performed to predict the life cycle of

the tool and to further ensure that the tool is safe for utilization prior to the clinical evaluation of the

prototype by the surgeon.

Keywords:

finite element analysis, fatigue, surgical tools, Nuss procedure



Paper 36

Title:

Examining CAD Interoperability through the Use of Ontologies

Authors:

Ramya T. Chaparala1, Nathan W. Hartman2 and John Springer3

1Purdue University, [email protected] 2Purdue University, [email protected] 3Purdue University, [email protected]

Abstract:

Product data interoperability in CAD systems has become one of the key areas of concern for

collaboration of work and integration of product data through various phases of a product lifecycle. In

this paper, we propose a framework which uses an ontology to bridge the data interoperability gap

between various CAD software systems allowing these systems to interact with each other during a

product’s lifecycle. An ontology is created from the native file from a CAD system through an

intermediate standard format, STEP. The ontology represents the geometric product data from the CAD

file and the semantics of the product data. The ontology is converted back into a STEP file to be used by

another CAD system. This could be an open source alternative to expensive proprietary software

packages used for this type of data conversion.

Keywords:

PLM, ontology, data interoperability, STEP, Protégé, OWL



Paper 37

Title:

Parameterized Geometric Design of a Generic Form Milling Cutter

Authors:

Mohammed Rajik Khan1 and Puneet Tandon2

1National Institute of Technology Rourkela, [email protected] 2PDPM‐Indian Institute of Information Technology, [email protected]

Abstract:

This paper presents the design methodology to develop a comprehensive geometric model for a generic

form milling cutter. Unlike conventional projected geometry approach, the geometric design of the form

milling cutter is modeled here using (a) composite NURBS curve to create the generic profile for the

multi‐cutting edges and (b) biparametric sweep and planar surfaces to form the rest of the geometry.

The methodology is illustrated by varying the dimensional and geometric parameters of the composite

model and generating a variety of cutters lying in the same conceptual family of generic form milling

cutter. The proposed method is validated by fabricating one of the form milling cutters.

Keywords:

parameterized geometric design, form milling cutter, generic profile



Paper 38

Title:

BIM‐based Computer‐Aided Architectural Design

Authors:

Yi‐Feng Chang1, Shen‐Guan Shih2

1National Taiwan University of Science and Technology, [email protected] 2National Taiwan University of Science and Technology, [email protected]

Abstract:

Computer‐aided architectural design is evolving from CAD (Computer‐aided drafting) to BIM (building

information modeling), which represents a progression from assisting designers to produce construction

drawings to facilitating design plan decision making and integration of AEC industry teams, which

involves the key aspects of information processing and exchange during the design stage. Information

processing and exchange during the design stage can be accomplished using a building information

model, which can yield the benefits of (1) comprehensive information, no omissions, and inclusion of all

information needed for operations; (2) no redundant information; and (3) no mutual contradictions plus

effective search and analysis functions. This study analyzes and compares the information processing

and integration methods of CAD and BIM systems from the perspective of computer‐aided architectural

design (CAAD), and proposes that BIM‐based CAD can boost the horizontal integration efficiency of

cooperating teams, and achieve vertical integration of information between different stages. Now that

BIM software is available, designers must transfer existing CAD systems data into BIM databases, and

use BIM technology to perform architectural design and transmit design information, boosting the

effectiveness of cooperation between architectural teams. In accordance with the AIA's level of detail

(LOD) standards, this study divides the design process into three stages (LOD100 to LOD300)

corresponding to the design key points and objectives during each stage, and conducts an actual design

case. Two design objectives are achieved through BIM use: (1) sustainability design of a green building

and (2) the use of BIM technology to perform building planning and design.

Keywords:

Computer‐aided drafting (CAD), building information modeling (BIM), information integration, level of

detail (LOD)



Paper 39

Title:

Context Dependent Automatic View Planning: The Inspection of Mechanical Components

Authors:

Roberto Raffaeli1, Maura Mengoni2, Michele Germani3

1Polytechnic University of Marche, [email protected] 2Polytechnic University of Marche, [email protected] 3Polytechnic University of Marche, [email protected]

Abstract:

Literature shows how 3D CAD product models can be used as reference in order to manage the

verification process by 3D optical scanning systems and the computation of the optimal viewpoints.

However, in the mechanical field, a variety of inspection tasks is experienced by engineers involved in

the quality control process: GD&T verification, production phases control such as sheet metal cutting,

evaluation of aesthetic appearance of parts, global shape deformation measurement and specific point

deviations assessment. This leads to the necessity of flexible view planning approaches which adapt to

the specificity of the required inspection task. The present work targets the development of a

comprehensive view planning approach in which several algorithmic options are triggered by the

product features to be inspected. Algorithms have been implemented in a prototypal software system

which has been experimented as an off‐line application to provide inputs to a multiaxis Degree of

Freedom (DoF) robot arm mounting an optical 3D scanner. Two test cases from die casting and

automotive fields are presented. They show the computation of acquisition poses in a suitable sequence

and efficiency in the obtained results.

Keywords:

GD&T, 3D scanning, Inspection, View Planning, Quality Control



Paper 40

Title:

Manufacturability Mode Analysis Formulated In Algebraic Mathematical Functions

Authors:

Ramy F. Harik1

1Lebanese American University, [email protected]

Abstract:

This paper presents an algebraic mathematical formulation for selecting the appropriate manufacturing

modes combinations to manufacture a featured part. In a first section we introduce the topic as well as

we forward a literature review. Then we present a set of algebraic definitions that will be used to

perform the manufacturability analysis selection. The third part will study the complete set of study

cases and propose the face repartition algorithm accordingly. The fourth part summarizes the proposed

methodology within a table. Finally a conclusion is presented.

Keywords:

manufacturing mode, mathematical formulation


Paper 43

Title:

A Survey to Evaluate How Non‐Designers Perceive Aesthetic Properties of Styling Features

Authors:

Franca Giannini1, Marina Monti2, Jerome Pelletier3 and Jean‐Philippe Pernot4

1Istituto di Matematica Applicata e Tecnologie Informatiche – CNR, [email protected] 2Istituto di Matematica Applicata e Tecnologie Informatiche – CNR, [email protected] 3Arts et Métiers ParisTech, LSIS Laboratory, UMR CNRS 6168, [email protected] 4Arts et Métiers ParisTech, LSIS Laboratory, UMR CNRS 6168, jean‐[email protected]

Abstract:

World‐wide market competition and the need to create products that better satisfy the market

expectations require a more comprehensive involvement of the customer in the product definition loop.

Therefore, it is crucial to provide customers with very easy‐to‐use shape definition and modification

tools, allowing them to verify and evaluate possible shape alternatives without requiring specific

knowledge on geometric modeling. A set of aesthetic properties guiding the shape characterization and

appraisal have been identified together with measures for their evaluation and shape modeling methods

for their direct modification. Since these properties have been indicated by stylists, no guarantee exists

that they are usable in a context directly involving customers in the product definition loop. To verify the

extent to which the terms indicating the properties, their meaning and their measures are significant

and understandable by non‐expert designer people we carried out a survey. This paper describes the

methodology adopted and the outcomes of this survey.

Keywords:

geometric modeling, styling, aesthetic features, semantic‐oriented 3D modeling



Paper 44

Title:

Analytical Modeling and Evaluation of Microneedles Apparatus with Deformable Soft Tissues for

Biomedical Applications

Authors:

Apichart Boonma1, Roger J. Narayan2, and Yuan‐Shin Lee3

1Industrial and Systems Engineering, North Carolina State University, [email protected] 2Biomedical Engineering, North Carolina State University, [email protected] 3Industrial and Systems Engineering, North Carolina State University, [email protected]

Abstract:

This paper presents an analytical modeling of microneedle insertion force to evaluate different

microneedle geometric designs. To analyze the microneedle insertion force, monotonous and

heterogeneous tetrahedral models of soft tissue were developed. This paper introduces a two‐stage

analytical modeling technique by considering different geometric design parameters. The method

divides microneedle insertion process into pre‐puncture and post‐puncture stages, and employs the

concept of finite element analysis, fracture mechanics and distributed load. Different microneedle

designs can be evaluated based on the geometric design parameters. Experiments were conducted with

both the linear elastic and the nonlinear finite element models. The microneedle geometry that provides

better tissue penetration and operation stability is selected and used for biomedical applications. The

presented techniques can be used in the design and developemnt of microneedles for biomedical

applications.

Keywords:

Biomedical device design, Soft tissue modeling, Geometry analysis, Biomedical applications



Paper 45

Title:

Quantitative Similarity Comparison based on Group Technology: Improving Quality of Data Retrieval for

CAD/CAM

Authors:

Leila Zehtaban1, Dieter Roller2

1Universität Stuttgart, [email protected]‐stuttgart.de 2Universität Stuttgart, [email protected]‐stuttgart.de

Abstract:

The high potential of optimizing a new product design with reusing know‐how of existing or previously

manufactured products has exceedingly attracted interests of manufacturers as well as designers.

Reusing existing know‐how has the potential to improve product quality, shorten the design lead‐time

and reduce costs. A key factor for a quick and precise accessibility and possibility of reusing the

accumulated knowledge is standardization and classification of the products in a repository. Between

the main methods for classification of geometrical and topological information of a 3D model, Group

Technology is the only method which contains additional information beside the geometry of a product.

This paper presents the state‐of‐the‐art of Group Technology in design and manufacturing as well as its

application as an optimization method for data retrieval of CAD models. The retrieval process is

performed with numerical (quantitative) calculation of the similarity comparison between the

requirements specification and the retrieved models.

Keywords:

Similarity comparison, Group Technology, CAD/CAM



Paper 47

Title:

Conceptual Full‐Vehicle Development supported by Integrated Computer‐Aided Design Methods

Authors:

Severin Stadler1, Mario Hirz, Katharina Thum and Patrick Rossbacher

1University of Technology Graz, [email protected]

Abstract:

Today’s automotive industry is characterized by a high product diversification in combination with

decreasing times‐to‐market. This leads to high demands on product development processes and

assumes the application of multidisciplinary and flexible virtual product development tools and

methods. The present publication introduces to the challenges of conceptual full‐vehicle development

and discusses the ability of applying a centralized product master model by an exemplarily illustration of

a 3D CAD approach. As a key aspect of this publication, a method for the support of geometrical full‐

vehicle development processes (e.g. geometrical integration, vehicle packaging) during early product

generation phases is presented and discussed in detail.

Keywords:

automotive concept development, packaging layout, CAD master model



Paper 48

Title:

Multiple View Motion Tracking of Gridded Surfaces using Topological Structure

Authors:

M. H. Kinsner1, T. S. Kenyon2, D. W. Capson3 and A. D. Spence4

1McMaster University, [email protected] 2McMaster University, [email protected] 3McMaster University, [email protected] 4McMaster University, [email protected]

Abstract:

This paper describes a novel algorithm for interframe motion tracking of gridded surfaces across close

range video sequences. The topological approach exploits the regular grid structure, simplifying feature

extraction requirements, and reducing dimensionality of the projective tracking problem from eight to

two. Multiple view grid asymmetry is implemented using loosely defined tracking fiducials that do not

need to be explicitly detected or measured. Results from an experimental setup validate the accuracy

and robustness of the algorithm. Timing results demonstrate throughput greater than the 15 frames per

second camera data acquisition rate.

Keywords:

computer vision, interframe motion, grid tracking, topological structure



Paper 49

Title:

Layered Pentahedral Mesh Generation for Biomechanical Geometries with Unclosed Surfaces

Authors:

Zhipeng Lei and Jingzhou (James) Yang1

Human‐Centric Design Research Laboratory, Texas Tech University, [email protected]

Abstract:

Available methods for automatic volumetric mesh generation require the inputted surface to be

watertight. However, biomechanical geometries obtained from a 3D scanner, computed tomography

(CT), or magnetic resonance (MRI) may not provide a closed surface. This paper proposes a layered

pentahedral mesh generation method for a biomechanical geometry that is defined by any unclosed

surface. Based on the initial geometries, two basic meshing problems for biomechanical model were

solved. One is that the biomechanical geometry is defined by two surfaces and the volume bounded by

the two surfaces is meshed. The other one is that the geometry defined by one surface and a list of

points is meshed where there are predefined depths on these points. A distance function was defined

for determining relative distance between a surface and a plane. The volumetric mesh was created by

adding layers of pentahedral elements, and these pendtahedral elements were smoothed using the

signal processing method. The proposed method was demonstrated with examples of meshing the

deadspace of headform/respirator and developing the finite element model of a human face with

different soft tissue thicknesses. Further, two applications, the CFD simulation of air leakage of

headform/respirator and finite element contact simulation between a headform and a respirator, used

the proposed method to create volumetric mesh. Results show that the proposed mesh method was

able to create biomechanical models with acceptable mesh qualities from highly curved geometries.

Keywords:

Layered pentahedral mesh, respirator, biomechanical geometry



Paper 50

Title:

B‐spline Surface Based Concept Design Module for Applications in Virtual Reality Environment

Authors:

Harish Pungotra1, George K. Knopf2 and Roberto Canas3

1Beant College of Engineering and Technology, India, [email protected] 2Western University , London, Canada, [email protected] 3National Research Council, Canada, roberto.canas@nrc‐cnrc.gc.ca

Abstract:

Over the past decade, B‐spline modeling has become the standard mathematical model for representing

freeform or organic objects in CAD/CAM systems. Using a B‐spline surface to represent the virtual model

in a haptic concept design module helps to streamline the exchange of the information with existing

CAD/CAM systems. B‐spline surfaces also help increase visual realism because these represent

continuous surface. At the same time, physically based virtual deformable models provide a sense of

realism to the user. However, the algorithms used for interaction with the virtual model should be

efficient to maintain acceptable level of virtual realism and perceive the simulation as continuous with

no time lag. This paper presents a B‐spline surface based concept design framework, which can be used

to generate various concepts, evaluate these concepts, and provide user training. The proposed

framework assumes that all deformable models are represented as B‐spline surfaces. The tools used to

interact with the deformable models can be implicit surface, tessellated surface, B‐spline surface, or

point‐based. The technique exploits blending matrices for the B‐spline surface that are independent of

the control point positions and, hence, can be pre‐calculated prior to haptic interaction. Once

determined, the pre‐calculated blending matrices are used to generate discrete points on the B‐spline

surface. Mass spring system is used to incorporate material properties to the virtual objects. Practical

illustrations of the concept design framework are presented for modeling and evaluation of concepts

and provide training to the intended user segment.

Keywords:

concept design, deformable model, virtual reality, modeling and simulation, B‐spline surfaces, blending

matrices



Paper 51

Title:

Reliable Surface Extraction from Point‐Clouds using Scanner‐Dependent Parameters

Authors:

Hiroshi Masuda1, Ichiro Tanaka2, and Masakazu Enomoto3

1The University of Tokyo, [email protected]‐tokyo.ac.jp 2Tokyo Denki University, [email protected] 3The University of Tokyo, [email protected]‐tokyo.ac.jp

Abstract:

Phase‐based and time‐of‐flight laser scanners can be used to capture dense point clouds of industrial

plants. Our goal is to reconstruct 3D models of components in industrial plants. For robustly extracting

surfaces, the standard deviation of residuals in surface fitting has large impact on the result. The

standard deviation is one of basic parameters in the least‐squares, robust estimate, region growing, and

RANSAC. However, it is not easy to estimate the standard deviations of fitting errors in a wide range of

field, because the standard deviations vary in a point‐cloud, according to the sizes, distances, and

materials of scanned objects. In this paper, we investigate the distributions of residuals in surface fitting

using experimental data, and derive prediction functions of the standard deviations for measurement

errors. Our experimental result shows that our prediction functions are effective for reliably extracting

surfaces of diverse sizes, distances, and materials.

Keywords:

point‐cloud, surface extraction, as‐built modeling, point processing



Paper 52

Title:

An Evaluation of Interactive and Automated Next Best View Methods in 3D Scanning

Authors:

Grigori D. Pintilie1 and Wolfgang Stuerzlinger2

1York University, Toronto, Canada, [email protected] 2York University, Toronto, Canada, [email protected]

Abstract:

Scanning of objects to produce 3D models is becoming more commonplace as the required hardware is

becoming less expensive and more widely attainable. The process involves obtaining scans of multiple

views so as to create a complete 3D model. This is typically a user‐driven process, and an analysis of the

difficulty of this task, use of automation, visualization methods, and their effect on the final result has

not yet been thoroughly investigated. In this paper we report on a user study related to 3D scanning in

which the user is asked to use a simulated, somewhat simplified 3D scanner with a simple user interface.

Our investigation focuses on scanning the complete surface of an object with decent sampling density,

but does not take all sampling issues, such as reflections, into account. We evaluate different

visualization methods, which aim to help the user complete or improve scans, and compare the results

obtained by participants to those obtained using an automated approach. The results show that users

can easily obtain complete scans or improve existing scans using this simple interface, and that different

visualization methods are more or less equally effective; moreover, user performance is on par with

automated scanning methods.

Keywords:

Human factors, humanizing engineering design, Reverse engineering



Paper 53

Title:

Draping Curves on Surfaces for Quad‐Meshing of Architectural Surfaces

Authors:

Sai Kit Fan1, Ajay Joneja2 and Shawn Wang3

1Hong Kong University of Science & Technology, [email protected]



Abstract:

Modern architectural projects increasingly use free form curved surfaces. These are eventually

fabricated out of a large set of simpler pieces, or tiles that are more economical to manufacture and

maintain. The most common tiling scheme is quadmeshing. Typical tiling approaches work in two stages:

an initial pattern of lines is generated to yield an initial tiling, followed by an adjustment stage that

optimizes the precise geometry of each tile. In this paper, we introduce an approach to address the first

stage: draping of aesthetic 2D curves onto 3D surfaces in order to create initial tiling patterns. We test

our approach by using a common aesthetic curve, the Archimedean spiral. Several examples from real‐

world projects are used to illustrate our method.

Keywords:

draping, architectural geometry, quad‐meshing, surface re‐meshing



Paper 54

Title:

A Conceptual Framework Based on Fractal Geometry for Design, Modeling and Rapid Prototyping of

Complex Geometric Shapes

Authors:

Dina Rochman1, Sergio Vázquez2

1México, Universidad Autónoma Metropolitana, Cuajimalpa [email protected] 2México, Universidad Autónoma Metropolitana, Cuajimalpa [email protected]

Abstract:

In the "Project GEMA" geometry and mathematics, 62 prototypes were created to establish a

conceptual and formal language of the internal architecture of the solids that maintains a progressive

continuity through mathematics, to explore and analyze the changes generated by the points, lines,

planes and volume of the cube, the sphere and the tetrahedron. The idea of this project came from

mixture of geometric graphics and mathematics to construct models in three dimensions using CAD

applications and rapid prototyping through the resources and elements of descriptive geometry. This

paper illustrates step by step the construction of the "Project GEMA"® cube # 022, from the standpoint

of mathematics and design with CAD applications.

Keywords:

Spatial reasoning, Polihedra, Digital technology, Rapid prototyping



Paper 56

Title:

A Bottom‐up Approach for Reconstructing 3D Models from Line Drawings

Authors:

Masaji Tanaka1, Tomoyuki Miyake2 and Kenzo Iwama3

1Okayama University of Science, [email protected] .ac.jp 2Okayama University of Science, [email protected] .ac.jp 3Engicom Corporation, k‐[email protected]

Abstract:

The automatic reconstruction of a 3D object from a single 2D line drawing as a sketch has been very

crucial research area since decades. Most of methods for the reconstruction have applied the technique

of line labeling. However, it would be often difficult to apply the methods when sketches have many

curved lines and have not any hidden lines. In this paper, a method whose approach is bottom‐up is

proposed. In this method, primitives and features are extracted repeatedly from sketches and they are

composed to reconstruct 3D models. New primitives and features can be always included as learned by

human when they are required in the more complex sketches of 3D objects. As the result, this method

can easily handle sketches that have many curved lines and have not any hidden lines. The effectiveness

of this method has been verified by experimental systems.

Keywords:

line drawing, sketch, reconstruction, bottom‐up, primitive, feature, CSG


Paper 57

Title:

Fast and Automatic Identification of Contours for Girth Measurement on 3D Human Models with Variant

Postures

Authors:

Zhanqing Chen1, Kai Tang2, Ajay Joneja3

1Hong Kong University of Science and Technology, [email protected] 2Hong Kong University of Science and Technology, [email protected] 3Hong Kong University of Science and Technology, [email protected]

Abstract:

We develop a novel method for fast and automatic identification of characteristic contours for

measuring girths on digital 3D human models with various stable postures. For fast identification, the

characteristic contours with salient topology and geometric features are selected among the multi‐

source geodesic iso‐contours, which are constructed under a new Morse function as using multi‐source

points to compute geodesic distance instead of using solely one source point. The resulting iso‐contours

are stable in a wide range of postures due to the bending invariance of geodesic distance. Based on the

characteristic contours, we develop an efficient algorithm to extract the contours for girth

measurement. We present a number of experiments on 3D human body samples with variant postures

to demonstrate the validity of our approach.

Keywords:

iso‐contour, girth measurement, posture



Paper 58

Title:

Surface Pattern Generation Using L‐system

Authors:

Pui Lam Chan1, Kin Chuen Hui2

1Chinese University of Hong Kong, [email protected] 2Chinese University of Hong Kong, [email protected]

Abstract:

The aim of this research is to create aesthetic patterns automatically on a mesh surface by using 2D

L‐system. Patterns are generated by providing cross‐sections and loci as elements to form tiles. They are

then packed together to form local pattern using 2D L‐system. Genetic Algorithm is adopted to optimize

the patterns. Finally cross‐section is blended on the mesh along a locus defined in each tile to form

surface. A non‐self‐intersecting offset surface is generated and its distance from the mesh surface is

used as a maximum height to prevent the pattern intersecting itself.

Keywords:

aesthetic, pattern, L‐system, Genetic Algorithm, tiling, geometric synthesis



Paper 59

Title:

An Approach of Irregular Porous Structure Modeling Based on Subdivision and NURBS

Authors:

S. T. Kou1, S. T. Tan2

1Department of Mechanical Engineering, The University of Hong Kong, [email protected] 2Department of Mechanical Engineering, The University of Hong Kong, [email protected]

Abstract:

Porous structure has its own unique advantages such as low relative density, high specific strength, high

specific surface area and good permeability etc., and these advantages lead to porous structure’s wide

application in the field of rapid manufacturing, lightweight design and tissue engineering. Porous

structure modeling, however, is a challenging task in CAD due to the difficulties in controlling the pore

shape, size, diversity and interconnectivity. In this paper, we present a method for irregular porous

structure modeling. Quadtree (Octree) is used to subdivide the modeling object into small sub‐regions

and the derived polygon (polyhedron) is generated in each of the sub‐region. T‐mesh is used in this

paper as a refinement tool for subdivision. Finally non‐uniform rational B‐spline (NURBS) curves

(surfaces) are generated using the derived polygon (polyhedron) as the control polygon (polyhedron).

Easy control of the structure size and interconnectivity is achieved through the flexibility and

independent characteristics of the quadtree (octree) structure and Tmesh. Structure irregularity is

obtained by creating NURBS features based on the derived polygons or polyhedrons.

Keywords:

porous structure modeling, subdivision, NURBS



Paper 61

Title:

Normal Vector Estimation for Point Clouds via Local Delaunay Triangle Mesh Matching

Authors:

Ji Ma1, Hsi‐Yung Feng2 and Lihui Wang3

1The University of British Columbia, [email protected] 2The University of British Columbia, [email protected] 3University of Skövde, [email protected]

Abstract:

Reliable estimation of normal vectors for point clouds is of practical importance in computer‐aided

geometric modeling and inspection. This paper introduces a new normal vector estimation method for

point clouds based on the matching results of the local Delaunay triangle mesh formed at each point.

The local mesh is a manifold patch of Delaunay triangles and resembles an open umbrella. According to

the matching results of these umbrellas, the local Delaunay neighbors at each point can be reliably

identified, which leads to accurate normal vector calculations. Compared with the existing methods, the

proposed method yields normal vectors of notably improved accuracy, especially for points near edge or

corner features. The improvement has been demonstrated using both simulated and scanned point

cloud data sets.

Keywords:

normal vector, point cloud, Delaunay neighbors, local mesh matching



Paper 65

Title:

A New Adaptive Slicing Approach to Control Cusp Height of Rapid Prototyping Parts

Authors:

S. Sikder1 , Ahmad Barari2, and H.A.Kishawy3

1University of Ontario Institute of Technology, [email protected] 2Corresponding Author, University of Ontario Institute of Technology, [email protected] 3University of Ontario Institute of Technology, [email protected]

Abstract:

Adaptive slicing in Rapid Prototyping Manufacturing (RPM) allows selection of layer thickness based on

desired quality of the final product, rather than using a constant layer thickness as seen in the common

practice. This type of slicing can be used to control part accuracy and the number of layer. Layer‐based

manufactured parts exhibit stair‐case effect which can be quantified by cusp height or the maximum

distance measured along a surface normal between Computer‐Aided Design (CAD) surface and the

produced layer. This paper proposes an improved adoptive slicing technique for rapid prototyping

implemented in a direct slicing platform. The developed procedure directly slices the CAD model

expressed in standard Initial Graphics Exchange Specification (IGES) format. The developed methodology

uses the allowable minimum and maximum thickness limits of RP machine, and the maximum

acceptable cusp height of the final part to calculate the number and thickness of the layers to slice the

solid model. A variety of experiments is conducted and the accuracy of the developed procedure is

compared with other slicing approaches.

Keywords:

Adaptive Slicing, Direct Slicing; Rapid Prototyping; Cusp Height, Layer Based Manufacturing


Paper 66

Title:

Optimization of Vehicle Structure Considering Torsion Stiffness Using Simple Structural Beam Frame‐

Approach

Authors:

Steven Tebby1, Ahmad Barari2 and Ebrahim Esmailzadeh3

1University of Ontario Institute of Technology, [email protected] 2Corresponding Author, University of Ontario Institute of Technology, [email protected] 3University of Ontario Institute of Technology, [email protected]

Abstract:

Vehicle structural design is an important component of automotive design since the structure of a

vehicle plays complex interactions with the other vehicle components and has significant impact on the

performance of the vehicle. Structural design is usually completed after many iterations and the design

changes in the late design stages effect many other parameters in the design of vehicle. Therefore, it is

highly valuable for designers to employ simple but effective analyses at the early design stages. One

method of analysis is using Simple Structural Surfaces. This method utilizes planar sheets to model the

vehicle structure and allows the determination of the forces in each sheet. The major drawback of this

method is its inability to determine deflections in a structure. To overcome this drawback a method that

uses beam elements to represent the vehicle structure has been developed. This method uses a

numerical finite element method and is able to determine unknown deflections and reaction forces as

well as the internal loading on each member. This method can also be readily adapted to allow for

parametric optimization for torsion stiffness. The parameters associated with each beam element are

the length, orientation and the beam characteristics of beams’ cross‐sectional area and moment of

inertia. An automated process is developed that manipulates some of these parameters to develop a

structure that will have the greatest torsional stiffness.

Keywords:

Stiffness Matrix Method, Automotive Structure, Finite Element Analysis‐Based Design, Beam‐Frame

Model



Paper 67

Title:

Algebraic Distance Field for Meshless Analysis of Free Form CAD Models

Authors:

Kritika Upreti1 and Ganesh Subbarayan2

1Purdue University, [email protected] 2Purdue University, [email protected]

Abstract:

In the class of problems containing embedded boundaries, the fields approximating behavior on the

boundaries are often blended with approximations built on the underlying domain using weight

functions. For example, analysis of objects in which bounding surfaces are embedded into regularly

structured grids, or when the boundaries are moved by the governing physics as in crack propagation or

solidification problems. The blending weight functions in the approximations are typically dependent on

the distance from the bounding surface. For general domains, bounded by free form curves or surfaces,

the distance fields have to be constructed numerically. This may require either a polytope

approximation to the boundary and/or an iterative solution to determine the exact distance to the

boundary. In this paper, we describe a purely algebraic, and computationally efficient, technique for

constructing distance measures as level sets from Non‐Uniform Rational B‐Splines (NURBS) boundaries

that retain the geometric exactness of the boundaries while eliminating the need for iterative distance

calculation. The level sets are constructed by implicitization of the constituent Bezier patches of the

NURBS surfaces. These implicit functions, however, extend beyond the parametric range of the Bezier

patch. Therefore, Boolean compositions with the convex hull of control polygon of the Bezier patch are

used to trim these global implicit functions. Further compositions are then carried out between

adjoining Bezier patches to describe a composed distance field over the domain. The compositions rely

on R‐functions that permit algebraic manipulations. Algorithms are also described to enable

computation of signed distance measure for bounded geometries. Geometry‐based (meshless) analysis

of freeform CAD models is demonstrated using the proposed technique through a set of linear elasticity

problems. The geometric models are assumed to be boundary representations (B‐rep) that do not

contain parametric description of the domain of analysis. The utility of the proposed technique is that it

enables direct analysis on these B‐rep CAD models without resorting to the tedious mesh generation in

the analysis domain.

Keywords:

Distance field, Implicitization, NURBS, R‐ functions, Meshless, Explicit



Paper 68

Title:

Modeling of Variational Gradient Porous Architecture with Multidirectional Filament Deposition in 3D

Scaffolds

Authors:

AKM Khoda1, Ibrahim T. Ozbolat2 and Bahattin Koc3

1University at Buffalo, [email protected] 2The University of Iowa, ibrahim‐[email protected] 3Sabanci University, Istanbul, [email protected]

Abstract:

Porous scaffolds with interconnected and continuous pores have recently been developed to stimulate

tissue regeneration. Even though few researches have focused on the internal architecture of porous

scaffolds but concluded that properly interconnected and continuous pores with spatial distribution

might perform diverse mechanical, biological and chemical functions of a scaffold. Thus the need for

reproducible and fabricatable scaffold design with controllable gradient porosity is obvious but is hardly

achieved because of design and fabrication limitations. In this paper, a novel functionally gradient

variational porosity architecture has been proposed with continuous material deposition planning

scheme. The medial axis transformation for the scaffold has been calculated to generate an internal

feature of the geometric domain. The medial axis is then used as a base to develop the medial boundary

to define the medial regions. Then the complex internal architecture of scaffolds is divided into sub‐

regions using the ruling lines that are generated between the slice’s contour and the medial boundary.

The desired controlled variational porosity along the scaffold architecture has been achieved with the

combination of two geometrically oriented consecutive layers while meeting the tissue scaffold design

constraints. This ensures truly porous structures in every direction as well as controllable porosity with

interconnected pores along the scaffold architecture. The proposed methodology has been

implemented and illustrative examples are also provided. A sample designed structure has been

fabricated with a NC motion controlled micro‐nozzle deposition system.

Keywords:

Medial axis, variational porosity, internal scaffold architecture



Paper 69

Title:

Three‐Dimensional Reconstruction of Large Micro‐CT Datasets of Vascular Corrosion Cast Using Parallel

Visualization

Authors:

William Lafayette Mondy1, Bhanu Rekepalli2, Pragnesh Patel

1Claflin University, Medical University of South Carolina, and Adiana Research and Development,

[email protected] 2University of Tennessee‐Oak Ridge National Laboratory, [email protected]

Abstract:

The inability to manage and process the large Micro‐CT datasets, and large 3D stereo lithographic image

files created using Micro‐CT methodology limits the volume of tissues reproducible in CAD with

microscopic details. We address the limitations in our ability to manage the large amounts of image data

generated by these methods by using supercomputer imaging technology based on NUMA architecture

which has 1024 cores, 4TBs of global shared memory, and 8 GPUs in a single system image called

Nautilus. Preliminary runs on Nautilus were able to generate a 3D model/STL file for approximately 70%

of the complete dermal vascular system of an adult New Zealand White rabbit skin vascular tree system

consisting of 3301 images (4000 by 4000 pixels) requiring more than 3 terabytes of shared memory. This

work investigates the architecture and shared memory requirement of supercomputers needed to

generate these models using various intensity levels for accurate data visualization which was previously

prohibited by desktop computers. Using interactive parallel visualization and graphical analysis for

contour plotting and generation of STL files we reduced memory footprint by removing noise from

datasets. In near future, we would like to conduct a contour spectrum to select important values from

datasets.

Keywords:

Dermal Vascular Tree; Capillary Bed; memory footprint; NUMA architecture


Paper 71

Title:

A method for designing users’ experience with industrial products based on a multimodal environment

and mixed prototypes

Authors:

Francesco Ferrise1, Monica Bordegoni2 and Serena Graziosi3

1Politecnico di Milano, [email protected] 2Politecnico di Milano, [email protected] 3Politecnico di Milano, [email protected]

Abstract:

The paper describes a methodology that can be employed to perform the analysis of aspects related to

human interaction with consumer products during the Product Development Process, thanks to the use

of mixed prototypes. The methodology aims at helping designers to take decisions earlier compared to

the current practice based on not easily modifiable physical prototypes. Authors’ method considers the

interaction with adaptable mixed prototypes as a possible validating procedure for product interaction‐

enabling features: a multimodal environment is created to perform these validations, integrating three

sensorial modalities such as vision, hearing and touch. The paper firstly describes the requirements for

the creation of the multimodal environment. Then it focuses on the opportunity of using an approach

based on mixed prototypes rather than on completely virtual ones: the intent is to increase the level of

“realism” of the simulation by overcoming limitations of actual technologies for the sense of touch.

Finally, a case study is discussed, starting from the analysis of a commercial consumer product up to the

interaction with the developed Mixed Prototype. The expected benefits for the product development

process are highlighted.

Keywords:

Virtual and Mixed Prototyping, Haptic Interaction, Product Virtualization



Paper 72

Title:

GPU‐Based Super‐Union for Minkowski Sum

Authors:

Yuen‐Shan Leung1, Charlie C.L. Wang2 and Yong Chen3

1The Chinese University of Hong Kong, [email protected] 2The Chinese University of Hong Kong, [email protected] 3University of Southern California, [email protected]

Abstract:

We present an efficient and robust algorithm to approximate the 3D Minkowski sum of two arbitrary

polyhedra on Graphics Processing Unit (GPU). Our algorithm makes use of the idea of super‐union, in

which we decompose the two polyhedra into convex pieces as usual, but the way we perform pairwise

convex Minkowski sum and merge the pairwise sums one by one is changed to group by group on GPU.

The core technique involved is to directly compute the convex hull of pairwise sum in image

representation and utilize voxelization to perform massive union operations. Despite the lack of

accuracy, we guarantee that the voxelization of Minkowski sum is conservative, and the inner voids are

well preserved. Our algorithm is also scalable and fits well into GPU’s streaming architecture.

Keywords:

Minkowski sum, Voxelization, Inner void, GPU, MAX/MIN blending



Paper 74

Title:

Smart Spatial Ontology: Bridging Semantic Ontology to Spatial Topology

Authors:

Chieh‐Jen Lin1

1Tainan University of Technology, [email protected]

Abstract:

This paper proposes a feasible approach named “Smart Spatial Ontology” for converting ontological

declarations into topological relations and geometric features, which would then assist users to retrieve

relevant cases from the case library. The purpose of this project is to extend the knowledge representing

abilities of our design case library, which develops smart retrieval of spatial topology within plan

drawings for assisting architectural design.

Keywords:

case‐based design; case library; spatial topology; semantic ontology



Paper 75

Title:

About the Introduction of a Dialogue‐Based Interaction within CAD Systems

Authors:

Niccolò Becattini1, Yuri Borgianni2, Gaetano Cascini3, and Federico Rotini4

1Politecnico di Milano (Italy), [email protected] 2Università di Firenze (Italy), [email protected] 3Politecnico di Milano (Italy), [email protected] 4Università di Firenze (Italy), [email protected]

Abstract:

CAD systems are nowadays extending their domain of application towards the preliminary phases of the

design process, with the emergence of Computer‐Aided Innovation – CAI. However, the first generation

of CAI commercial software is far from achieving the intended objectives; among them, the diffused

TRIZ‐based systems made no exception. Particular limitations are highlighted within the embodiment

design stage with reference to the support provided by CAx tools in fulfilling product specifications,

whenever the generated solutions do not satisfy system requirements. The authors propose to

overcome the current limitations by implementing a dialogue based system into the framework of

existing CAD applications, to support the designer in overcoming problems emerged during the initial

design stages. The manuscript illustrates a refined set of requirements for a Dialogue‐Based CAD system

according to the outcomes of a testing campaign carried out with a preliminary version of a question‐

answer framework. The proposed instrument is capable to measure the achievement of all the major

characteristics highlighted by the survey of established models for carrying out embodiment design.

Keywords:

Dialogue‐based interaction; Innovation; Problem Solving; Embodiment Design



Paper 76

Title:

Interactive Virtual Prototypes for Testing the Interaction with New Products

Authors:

Francesco Ferrise1, Monica Bordegoni2 and Umberto Cugini3

1Politecnico di Milano, [email protected] 2Politecnico di Milano, [email protected] 3Politecnico di Milano, [email protected]

Abstract:

Today, the tests of a new product in its conceptual and design stage can be performed by using digital

models owning various levels of complexity. The level of complexity depends on the nature and on the

accuracy of the tests that have to be performed. Besides, the tests can involve or not the interaction

with humans. Particularly, this second aspect must be taken into account when developing the

simulation model. In fact, this introduces a different kind of complexity with respect to simulations

where humans are not involved. Simulation models used for numerical analyses of the behavior of the

product (such as Finite Element Analysis, multi‐body analysis, etc.) are typically named Digital Mock‐Ups.

Instead, simulations that are interactive in their nature, requiring humans‐in‐the‐loop, are named

interactive Virtual Prototypes. They cannot be intended as a simple upgrade of a CAD model of a

product, but they are instead a combination of functional models, mapped into sensorial terms and then

accessed through multisensory and multimodal interfaces. In this paper, the validity of this concept is

demonstrated through some case studies where interactive Virtual Prototypes are used to substitute

the corresponding physical ones during activities concerning the product conceptualization and design.

Keywords:

Virtual Prototyping, Mixed Prototyping, CAD modeling, Simulations



Paper 77

Title:

Networking Architecture for a Multi‐User FEA Pre‐Processor

Authors:

Prasad Weerakoon1, James Wu2, Tim Bright3, Chia‐Chi Teng4, Ed Red5, Greg Jensen6 and Karl Merkley7

1Brigham Young University, [email protected] 2Brigham Young University, [email protected] 3Brigham Young University, [email protected] 4Brigham Young University, [email protected] 5Brigham Young University, [email protected] 6Brigham Young University, [email protected] 7Computational Simulation Software, LLC, [email protected]

Abstract:

Current computer‐aided engineering applications (CAx) only allow a single user to create/manipulate

geometry and prepare the model/assembly for analysis at a given time. These engineering applications

do not support multiple users to make changes to the model/assembly simultaneously. Though there

are some collaborative tools embedded within these applications, they are limited to simple interactions

such as screen sharing, conference calling, instant messaging, etc. In the Product Development (PD)

cycle, a considerable amount of time is spent in preparing the model/assembly for Finite Element

Analysis (FEA). This paper discusses the architectural considerations that were taken into account to

allow multiple users to work on the same model in CUBIT (a commercial FEA mesh generation software).

Keywords:

Multi‐user architectures, ipc, named pipes, collaborative architectures, CAx



Paper 78

Title:

Mesh Simplification Based on Feature Preservation and Distortion Avoidance for High‐Quality

Subdivision Surfaces

Authors:

Tetsuo Oya1, Toshiyuki Tanamura2, Hideki Aoyama3 and Masatake Higashi4

1Keio University, [email protected], [email protected], [email protected] 2Keio University, [email protected], [email protected], [email protected] 3Keio University, [email protected], [email protected], [email protected] 4Toyota Technological Institute, higashi@toyota‐ti.ac.jp

Abstract:

We propose a mesh simplification scheme that can reduce the number of meshes to the requested

number while uniform and high‐quality base meshes for subdivision surfaces. In this paper, a modified

QEM (Quadric Error Metrics) scheme is proposed to obtain high‐quality subdivision surfaces on which

sharp features exist. To meet the requirements for surface quality and precise feature expressions, we

combined mesh distortion check and feature preservation with the QEM scheme. We demonstrated our

algorithm using some models including complex shapes, and the demonstrations showed the

effectiveness of the proposed method.

Keywords:

Reverse engineering, subdivision surface, mesh simplification, and feature preservation.



Paper 79

Title:

Determination of Elbow Flexion‐Extension Axis Based on Planar and Closed B‐Splines

Authors:

Kamal Mostafavi1, O. Remus Tutunea‐Fatan2, Emily Lalone3, Graham J. W. King4 and James A. Johnson5

1The University of Western Ontario, [email protected] 2The University of Western Ontario, [email protected] 3The University of Western Ontario, [email protected] 4The University of Western Ontario, [email protected] 5The University of Western Ontario, [email protected]

Abstract:

Accurate determination of the flexion‐extension axis of the elbow affects the outcome of implant

replacement. The current study proposes an automated approach capable of determining the FE axis

based on a stack of axial computer tomographic (CT) imaging slices of the distal humerus. The core of

the algorithm consists of an original technique employing control polygon deformation used to

approximate the segmented outer cortical bone points with closed B‐Splines, followed by curvature

based and least squares fitting methods for determination of the two relevant geometric centers. The

new approach was validated against a conventional voxel based FE axis determination procedure

involving marching cubes algorithm.

Keywords:

elbow flexion‐extension axis, distal humerus, B‐Spline based shape approximation, curvature‐based

feature recognition, least squares fitting, voxel‐based representations



Paper 80

Title:

Integration of Additive Manufacturing and Virtual Verification Strategies within a Commercial CAM

System

Authors:

R. W. Hedrick1 and R. J. Urbanic2

1CNC Software, Canada, [email protected] 2University of Windsor, [email protected]

Abstract:

Additive manufacturing (AM) processes are becoming more common; however, there is little process

planning control. Standalone proprietary software is used by AM systems to create a build file that

displays the travel paths, but not a complete representative model, which may not be optimal.

Integrating AM into existing CAM systems provides a direct link between the CAD model and the AM

build file, as well as allowing planners to directly combine additive and subtractive operations. When

considering the number of entities and constraints related to the travel paths, most of the AM processes

are a derivative of the Fused Deposition Modeling (FDM) process; consequently, modeling the FDM

process within a commercial CAM system is the focus of this research. An AM user interface and a

process verification system based on the X3D standard is developed, as current machining verification

solid modeling kernels have been found to not be suited due to the number of entities to be processed.

Various examples are presented to highlight the merits of the approaches taken.

Keywords:

Additive manufacturing, tool path generation, computer aided manufacturing simulation tools



Paper 81

Title:

Targeted Reverse Engineering Techniques for Generating Architectural Solid Models for Additive

Manufacturing Fabrication

Authors:

R. J. Urbanic1, M. Kilani2 and A. Hassoun3

1University of Windsor, [email protected] 2University of Windsor, [email protected] 3University of Windsor hassouna @ uwindsor.ca

Abstract:

Additive manufacturing (AM) technologies enable designers to readily fabricate a physical model of a

complex free form object; however, a ‘water tight’ model is required for effective fabrication. To create

the CAD model for a classical building that has limited relevant structural information, reverse

engineering techniques must be applied. Using digital images, similarity and pattern analyses, a full solid

model of key exterior and interior features was generated in a systematic manner for manufacture using

the 3D Printing process. Feature geometry consisted of lines, arcs, extruded, swept, and revolved solids.

Design redundancies were leveraged to ignore noise due to the data collection or building variations. 3D

Printing technology specific constraints needed to be addressed, such as altering wall thicknesses for

appropriate model strength, and providing assembly interfaces to allow for ease of assembly and

disassembly. This approach is most appropriate for buildings that do not contain complex free form

geometry, and is illustrated using a case study: Assumption University in Windsor, which was founded in

1857 and is administered by the Congregation of St. Basil.

Keywords:

Reverse Engineering, Architectural Replica Model, 3D Printing



Paper 82

Title:

Towards a Feature‐Based Agent‐Driven NC Tool Path Generation to Support Design and Process Changes

Authors:

Wei Wang1, Yingguang Li2 and Yongsheng Ma3

1Nanjing University of Aeronautics and Astronautics, [email protected] 2Nanjing University of Aeronautics and Astronautics, [email protected] 3University of Alberta, [email protected]

Abstract:

On the shop floor of manufacturing aircraft structural parts, design changes and machining process

changes accompany the entire development cycle of aircraft products. Such constant changes represent

a typical characteristic of a dynamic and integrated design and manufacturing environment. For such an

environment, a feature‐based, and agent‐driven automatic numerical control tool path generation

method is proposed in this paper. An object‐oriented collaboration framework is employed to

implement well‐defined machining features which keep engineering knowledge about tool path

generation, and those involved processes. Agents are used for collaboration control, function services

and domain mediation to propagate design and process changes to machining features. Machining

features are activated by agents to make the proper responses automatically. A prototype for feature‐

based tool path generation has been developed to verify the proposed method.

Keywords:

feature‐based machining, agent, tool path generation, aircraft structural part



Paper 83

Title:

Multi‐view Feature Model Representation to Support Integration of Chemical Process and Mechanical

Design

Authors:

Yanan Xie1, Jingxing Wei2 and Yongsheng Ma3

1University of Alberta, [email protected] 2University of Alberta, [email protected] 3University of Alberta, [email protected]

Abstract:

Increasingly extensive attentions have been given for the collaboration between chemical process and

mechanical design teams, especially for large scale energy industries such as oil sands mining, upgrading

and refining. The innovation of this proposed approach is to provide efficient and flexible information

share capability between different engineering departments. In this direction for the oil industry, as an

example, the information flow between chemical process engineering and mechanical engineering

domains is very crucial. Currently the engineers working for these two fields use different engineering

platforms whose information are also isolated. In this paper, a system design with the generic data

framework is proposed to facilitate the sharing of information and to help the design from different

aspects using multi‐view feature technology. A preliminary scenario has been implemented with NXTM

and SmartPlantTM software tools. It has been proved that under the proposed system design, engineers

working on these two domains can integrated their work coherently and share different information and

constraints consistently.

Keywords:

multiple view; feature‐based integration; generic feature; collaborative engineering



Paper 84

Title:

Tolerance allocation Based on the Minimum Deformation Zone of Finite Element Structural Frame

Analysis

Authors:

Ahmad Barari1

1University of Ontario Institute of Technology, [email protected]

Abstract:

As a design and manufacturing principle the combination of the actual deformations in a designed

mechanical part due to all of its service loads and the deviations due to all of its manufacturing and

production uncertainties should be equal or less than its maximum acceptable total geometric and

topological deviations that can satisfy its form, fit, and function requirements. Therefore, precise

knowledge of the actual deformations of mechanical components under the applied loads and boundary

conditions need to be used to allocate suitable tolerances. However, this process is optimized only if the

minimum geometric zone that covers the evaluated deformations is studied properly. In order to

achieve this goal, the concept of minimum deformation zone is introduced in this paper. Using this

concept, a unified methodology is developed to find the optimum tolerances for the geometric

parameters of mechanical frame structures. Validity of the developed procedure is studied by

conducting case studies and variety of experiments. The developed methodology can be employed

efficiently during detailed design process in a Computer Aided Design environment.

Keywords:

Tolerance Analysis, Minimum Deformation Zone, Geometric Deviations, Finite Element Analysis



Paper 86

Title:

Mapping Causal Relationships and Conflicts among Design Parameters and System Requirements

Authors:

Niccolò Becattini1 and Gaetano Cascini2

1Politecnico di Milano – Dipartimento di Meccanica, [email protected] 2Politecnico di Milano – Dipartimento di Meccanica, [email protected]

Abstract:

This paper proposes a Computer‐Aided tool aimed at increasing the efficiency of the Product

Development Process by bridging the definition of system requirements to the preliminary assessment

of the impacts of design choices on product characteristics. In details, it supports the designer in the

definition of desired and undesired characteristics of a technical system throughout its entire lifecycle,

according to a standardized set of criteria for eliciting and organizing knowledge from experts. The

Computer‐Aided tool also assist the user in managing the complex network between design variables

and system requirements, characterizing their cause‐and‐effect relationships with the objective of

determining critical parameters for product design. The paper also presents an exemplary application of

the software prototype in the field of washing machines with the purpose of highlighting that a

progressive integration of this kind of instruments into existing CAD/CAE tools also allows to promptly

determine a connection between requirements and objectives of physically based simulations.

Keywords:

System requirements; design variables, system parameters; causal relationships; Product Lifecycle

Management



Paper 87

Title:

Gesture Interface for 3D CAD Modeling using Kinect

Authors:

Dipen Dave1, Ashirwad Chowriappa2 and Thenkurussi Kesavadas3

1Virtual Reality Laboratory, University at Buffalo, [email protected] 2Virtual Reality Laboratory, University at Buffalo, [email protected] 3Virtual Reality Laboratory, University at Buffalo, [email protected]

Abstract:

Modeling in general can be viewed as a two‐step process, the first being concept visualization followed

by the final design. Most designers who work with CAD systems go through the concept visualization

stage and follow the same steps required in the final design stage. A standard approach to concept

visualization is traditionally performed using clay modeling, yet there is a lack of computer aided design

tools that can faithfully mimic the process of traditional clay modeling both in terms of representation of

virtual clay as well as an immersive user interface capable of capturing the user’s intent in an intuitive

sense. In this paper we describe a voxel based representation of virtual clay and introduce a hierarchical

gestural interface using Kinect which together brings the intuitiveness of traditional clay modeling to a

CAD environment. The framework was validated using a 3D clay modeling software (n=13). Results

showed that most of the participants were able to adapt to the new interface quickly.

Keywords:

Free form modeling, virtual clay, Kinect Gesture interface



Paper 88

Title:

Virtual Testing Laboratory for Lower Limb Prosthesis

Authors:

Giorgio Colombo1, Giancarlo Facoetti2 and Caterina Rizzi3

1Politecnico di Milano, [email protected] 2Università di Bergamo, [email protected] 3Università di Bergamo, [email protected]

Abstract:

This paper presents an environment, named Virtual Testing Lab‐VTL, where the orthopedic technicians

can test the prosthesis replicating the traditional procedures. It is part of an innovative design

framework centered on digital models of the whole patient or of his/her anatomical districts, which

constitute the backbone of the whole prosthesis design process. The virtual lab permits to realize a

complete amputee's digital model, an avatar, by which it is possible to execute prosthesis set up and

evaluate its functionality simulating postures and movements. First, we describe the state of art of

techniques used, i.e., virtual humans and motion capture systems. Then, the application of virtual

humans for the prosthesis design and simulation is presented as well as preliminary results.

Keywords:

Virtual human, prosthesis design, virtual testing



Paper 89

Title:

Embedded CFD Simulation for Blood Flow

Authors:

Simone Bartesaghi1, Giorgio Colombo2

1Dipartimento di Meccanica, Politecnico di Milano, [email protected] 2Dipartimento di Meccanica, Politecnico di Milano, [email protected]

Abstract:

The aim of the study is the analysis of strategies and parameters to automate CFD simulations. The idea

is to perform an Embedded CFD simulation for product development and verification. This work focuses

on biomedical problems, in particular on vessel bifurcations with aneurysm located in the circulatory

system. The research is conducted by the analysis of the pre‐processing, solving and post‐processing

steps, in order to find a methodology that involves the reliable calculation of the CFD variables. For the

pre‐processing step, spatial grids study is conducted to find the element density that allows efficient

calculations. The evaluations are done on a blood flow through an ideal artery bifurcation aneurysm.

Subsequently the time step entity and the maximum inner iteration number are studied to calculate the

independent variables. The time step is evaluated on the ideal bifurcation aneurysm with a constant

inlet flow velocity, while the maximum inner iteration value is evaluated on the ideal bifurcation with a

time dependent inlet flow velocity. The last study of the preprocessing is conducted on a reconstruction

of real artery bifurcation aneurysm, modified with the extrusion of the inlet region, that allow the

complete velocity field to develop. For each one, the original and the modified models, it’s generated an

unsteady simulation with set up in agreement with previous steps. A correct postprocess management

study done through the pulsatile non‐stationary simulation. The solution data will be used for the post‐

processing evaluations. So pressure and velocity evaluation layouts will be identified; Wall Shear Stress

(WSS) based indices evaluation layouts will be implemented in order to enable a better evaluation of the

case: Time Averaged Wall Shear Stress, Oscillatory Shear Index, Relative Residence Time. Lastly it will be

considered a layout about Q‐Criterion evaluation. The procedures defined during the study enable a

partial automation of the CFD simulations. Acquiring an arterial bifurcation aneurysm model is possible

to proceed to the automatic spatial grids generation; the numeric model is used to resolve unsteady

flow, set with optimal parameters. Finally it is possible to evaluate the calculated variables by means of

appropriate diagrams generation.

Keywords:

CFD, KBE, Hemodynamics



Paper 90

Title:

A new branching method for solid CAD models

Authors:

Ujjaval Gupta1, Vishal Wagholikar2, Stuti Awasthi3 and Amba D. Bhatt4

1Motilal Nehru National Institute of Technology, Allahabad, [email protected] 2Motilal Nehru National Institute of Technology, Allahabad, [email protected] 3Motilal Nehru National Institute of Technology, Allahabad, [email protected] 4Motilal Nehru National Institute of Technology, Allahabad, [email protected]

Abstract:

Three dimensional model reconstruction of human body parts is an important area of research in

biomechanical engineering. These models are constructed using CT scan or MRI scan data which is a

stack of two dimensional slices. However some of the human body parts like bones have complex

shapes and this causes some of the CT scan slices to carry multiple cross sections. Accurate

representation of such intricate shapes is a great challenge for scientists. In this paper we have

proposed a new method of branching for generating 3D solid CAD models. As an example of branched

object, we have used CT scan data of proximal femur and B‐spline triparametric hyperpatch approach is

used to represent solid model.

Keywords:

CAD model branching, B‐Spline, CAD model sectioning


Paper 91

Title:

Stress Analysis of Second Molar Tooth

Authors:

Jasvir Singh1 and Amit Kohli2

1D.A.V Institute of Engineering and Technology, [email protected] 2D.A.V Institute of Engineering and Technology, [email protected]

Abstract:

It is well known fact that molar tooth of human being faces different loading conditions. In this paper a

general model is made in Pro‐Engineer to carry out analysis of second premolar tooth of human using

Finite Element Analysis(FEA). Also the effect of breaking hard objects like walnut on teeth and stress

distribution under this loading condition is considered. This analysis has been carried out seamlessly

between CAD and FEA. As the stress distribution is an important factor for many types of dental

treatments, including designing dental implants, applying restoration etc., the results of this paper will

help in understanding the way in which stresses are distributed in dental structures.

Keywords:

Pro‐Engineer, walnut, CAD, FEA



Paper 92

Title:

An Alternative Methodology to Represent B‐spline Surface for Applications in Virtual Reality

Environment

Authors:

Harish Pungotra1, George K. Knopf2 and Roberto Canas3

1Beant College of Engineering and Technology, India, [email protected] 2Western University, Canada, [email protected] 3National Research Council, Canada, roberto.canas@nrc‐cnrc.gc.ca

Abstract:

B‐spline representation is one of the main methods for free‐form surface modeling and has become the

standard for CAD systems. However, in Virtual Reality (VR) environment, when a B‐spline surface

deforms, the blending functions need to be continuously computed. The high computational cost of

continuously calculating the blending functions for merging, collision detection and physics‐based

deformation system, while the model is deforming, restricts the use of B‐spline representation in a VR

environment. This paper presents an alternative methodology to represent B‐spline surface patches for

an interactive VR environment. A uniformly discretized B‐spline surface patch can be represented by a

set of control points and two precalculated B‐spline blending matrices. The proposed technique exploits

the fact that these B‐spline blending matrices are independent of the position of control points and

therefore can be pre‐calculated. The blending matrices enable the algorithm to merge B‐spline surface

patches, accurately check the collision, and generate nodes for the mass spring system to determine

deformation using the physics‐based model. This technique does away with the need to calculate

computationally intensive blending functions for the Bspline surfaces, and inverse of large matrices

during the run‐time. The computational efficiency achieved by using blending matrices helps to achieve

real time interactions between the virtual model and the tool. The results of computational cost of

haptic interaction are presented in this paper to prove the efficacy of the proposed methodology.

Keywords:

B‐spline surface, blending matrices, collision detection, deformable objects, virtual reality, and physics‐

based modeling



Paper 93

Title:

Considerations for Multi‐User Decomposition of Design Spaces

Authors:

Edward Red1, Felicia Marshall2, Prasad Weerakoon3, C. Greg Jensen4

1Brigham Young University, [email protected] 2Brigham Young University, [email protected] 3Brigham Young University, [email protected] 4Brigham Young University, [email protected]

Abstract:

The advent of multi‐user computer‐aided applications (CAx) like multi‐user‐CAD/CAE/CAM will change

personnel/organizational assignment processes in product development. In the near future

collaborating personnel/organizations will enter design sessions and simultaneously edit/review design

spaces. This paradigm shift will require new methods to be developed that decompose development

tasks over personnel/organizations at both local and global locations. Experiential data will not be

restricted to suppliers, organizations, or sites, or other grouping types, but reflect a different granularity

where a particular group of individuals from a variety of organizations might be collected into design

teams for optimal collaboration. This paper will consider general collaborative principles from two

perspectives: 1) from an administrative perspective and 2) from simple CAx prototypes that

demonstrate how to decompose complex design models among several multi‐users. Thus, the paper

considers the decomposition challenges that must be resolved from project administration to project

conduct, i.e., from the top down. The paper demonstrates that modern CAx applications already have

some of the tools needed for multi‐user decomposition, if not the mentality.

Keywords:

Collaborative design, multi‐user decomposition



Paper 94

Title:

The Analysis of T‐spline Fairness

Authors:

Wang Aizeng1, Zhao Gang2

1Beihang University, [email protected] 2Beihang University, [email protected]

Abstract:

The fairness of curves and surfaces has been used in the shape design of industrial products more and

more widely. With the wide applications of T‐splines in the surface modeling, this paper analyzes the

fairness of T‐splines and gives some fairness properties of standard T‐splines and semi‐standard

T‐splines. For some special Tsplines, this paper proposes a method of comparing the T‐spline fairness.

The research will contribute to the relevant research of T‐spline fairing algorithms, and will contribute to

the applications of T‐splines in computer‐aided manufacturing.

Keywords:

T‐spline, fairness, surface



Paper 96

Title:

Building Editable Free‐form Models from Unstructured Point Clouds

Authors:

Ioannis Kyriazis1 and Ioannis Fudos2

1University of Ioannina, [email protected] 2University of Ioannina, [email protected]

Abstract:

We present a novel approach to reconstructing the surface of a 3D object using a point cloud of its

surface scan. The objective is to obtain an editable CAD model that is manufacturable and describes

accurately the structure and topology of the point cloud. The point cloud is sliced into cross sections.

Each cross section is represented as a 2D point set. Then, a collection of interpolating curves is

computed that describes each cross section accurately, using computational geometry methods on the

corresponding point set. The organized point set for the surface reconstruction is obtained from these

curves. Freeform transformations may also be applied, allowing high level global editing of the final

object.

Keywords:

surface reconstruction, cross sections, transformations


Paper 97

Title:

Multi‐objective Optimal Design of Driving Spring in Slide Cover Hinge

Authors:

Alan C. Lin1 and Tu‐Chuan Wang2

1National Taiwan University of Science and Technology, [email protected] 2National Taiwan University of Science and Technology, [email protected]

Abstract:

Combining Taguchi experimental design and fuzzy theory, this research aims to develop a multi‐

objective algorithm to determine the optimal design parameters for the driving springs in a slide cover

hinge. The goal is to determine parameters that will meet the two basic requirements of the spring that

would generate adequate reaction force but minimize maximum stress. This research applies finite

element method to calculate the reaction force and maximum stress of a deformed spring. Meanwhile,

the Taguchi method, which could dramatically reduce the number of experiments, is used to determine

the optimal design parameters for the spring. Experimental results suggest that if the maximum stress is

minimized, the reaction force will decrease, resulting in the autonomous release of the slide cover

hinge; if adequate reaction force is achieved, the maximum stress would exceed the design standard.

Therefore, this research employs fuzzy theory to achieve multi‐objective as “minimization of maximum

stress” and “sufficient reaction force”, as a result of an optimal design for driving springs in a slide cover

hinge.

Keywords:

Finite element method, Taguchi method, Fuzzy theory, Multi‐objective algorithm, Slide cover hinge



Paper 99

Title:

Milling of Weld Fillets with Variable Assembly Geometry

Authors:

Yu Pin Lin1, D. Alan Sawula2, Allan D. Spence3, and Robert V. Fleisig4

1McMaster University, [email protected] 2McMaster University, [email protected] 3McMaster University, [email protected] 4McMaster University, [email protected]

Abstract:

Assembled components are often welded together. To avoid fluid flow disruption or fatigue cracking,

the weld surface may be smoothed by milling. Actual assembly geometry may deviate from the CAD

model, and hence nominal CNC tool paths must be adjusted to achieve a continuous blend with actual

neighbouring surface measurements. This paper describes a laser digitizer inspection, tool path

adjustment, and milling workflow for smoothing welds between two adjacent assembly components.

Keywords:

gas turbine blade, point cloud, CAD/CAM, laser digitizing


Paper 100

Title:

Assessment of CAE Results Acquired Using Different Engineering Simulation Tools

Authors:

Elias. N. Atallah1, Ahmad. K. Zein2 and Ramy F. Harik3

1Lebanese American University, [email protected] 2Lebanese American University, [email protected] 3Lebanese American University, [email protected]

Abstract:

Nowadays, numerical analysis software is heavily used to validate results obtained in real life. In the

market, the available and most commonly used simulation tools are ANSYS and Fluent for CATIA (FfC).

In this paper, a research will be conducted to formulate a methodology of analyzing the difference

between software knowing that they all follow an iterative simulation approach. Our study will be based

on many parameters such as CAD modeling, processing time, accuracy, interface, post processing and

installation cost.

This comparison requires at first designing a standard common geometry which will be used as an input,

then, the numerical analysis will take place. For instance, the imported shape can be meshed and then

using a finite element method, an output will be generated. A link between ANSYS and FfC will be

emphasized in order to acquire the basic advantages and drawbacks of each one since they are all

somehow compatible and similar in terms of solution computation. Concerning the output, all software

will eventually generate a result, but they mainly differ in accuracy and convergence time. The objective

of this research is to guide users towards choosing the most suitable software within their constraints.

Keywords:

CAE, CFD, FEM, Comparison, Assessment, ANSYS, FfC


Paper 101

Title:

An Interface Based API for Mesh Visualization

Authors:

Michael M. Heck1, Pascal Doux2 and Jean‐Michel Godinaud3

1Visualization Sciences Group, [email protected] 2Visualization Sciences Group, [email protected]

Abstract:

We present the design and implementation of MeshViz XLM™, an interface based API for mesh

extraction and visualization. Large meshes and the associated data are a key challenge in application

domains such as finite element analysis, computational fluid dynamics and reservoir engineering. Our

design uniquely takes advantage of interface based programming to enable tight integration with the

application’s data without actually knowing anything about the application’s data structures. As a result

the API avoids duplication of application data, supports any type of data structure and data type and

supports features required by state of the art solvers such as polygonal cells and parametric nonlinear

cells. In addition the API presents a consistent model where “everything is a mesh” and cleanly

separates extraction of derived meshes from visualization techniques. For example, an isosurface is not

a visualization technique as in some APIs. An isosurface is a surface mesh extracted from a volume

mesh. Contour lines are a set of line meshes extracted from a surface mesh and so on.

Keywords:

graphics API, mesh extraction, mesh visualization


Paper 146

Title:

Printable Micro‐fluidic Channels towards Organ Printing

Authors:

Yahui Zhang1, Howard Chen2 and Ibrahim T. Ozbolat3

1The University of Iowa, yahui‐[email protected] 2The University of Iowa, howard‐[email protected] 3The University of Iowa, ibrahim‐[email protected]

Abstract:

Organ printing is a complex and challenging process due to the lack of fundamental understandings of

tissue and organ formation, and problems associated with giving the organ‐conforming 3D shapes. One

of the major challenges is the inclusion of blood vessel‐like channels to provide nutrient and oxygen

transport between layers to aid in the support viability of cells. While tissue scaffolds have been widely

used in the generation of replacement tissue by providing mechanical support and microfluidic

connections, problems with scaffold degradation and corresponding adverse effects on extra cellular

matrix are present. This paper introduces a basis for scaffold‐free architecture for cellular assembly to

minimize these problems. This research investigates manufacturability of new printable micro‐fluidic

channels, which can provide mechanical integrity and fluid transport in 3D. A pressure assisted freeform

fabrication platform is developed with a co‐axial needle dispenser unit to print hollow alginate

filaments. The printed hollow filaments are used to support nutrients and oxygen transport through the

printed cell assembly.

Keywords:

Tissue engineering, biomanufacturing, micro‐fluidic channels


Paper 147

Title:

An Object Oriented Approach to the Online Simulation of CNC Turning and Milling Machining Operations

through Computational Geometry

Authors:

Vikas K. Malviya1 and Prashant K. Jain2

1PDPM Indian Institute of Information Technology, [email protected] 2PDPM Indian Institute of Information Technology, [email protected]

Abstract:

This paper presents an approach to the simulation of the CNC turning and milling operations. Object

oriented approach is selected as it is perfectly suitable for the development of simulation system .In that

approach the problem can be decomposed in objects that are real time entities. Object oriented analysis

and design (OOAD) is used for the analysis of problem and the design of the solution in terms of objects.

OOAD uses object‐oriented perspective to model a system as group of interacting objects that work

together to perform required functionality. The analysis has been performed and the modeling has been

done with Unified modeling language (UML). For the verification of the analysis and design, online

simulation software for the CNC turning and milling operations has been developed. The simulation

facility is provided not only for simpler codes but also for the codes with canned cycles. For the

simulation of various canned cycles present in part program, the software first simplifies them into

simpler codes without canned cycles and then simulate it. The simplified program obtained from the

software can be saved by the user and can be used on other machines that don’t have the facility to run

canned cycles. For the development of the software Java platform has been selected. Key technologies

used for the development of software are JSP (Java server pages), Java applet and HTML (Hyper text

markup language). Simulation software is available online at the URL “http://virtualcnc.iiitdmj.ac.in”.

Keywords:

Object oriented approach, Java, Canned cycles



Paper 148

Title:

A Graph Theoretic Approach for the Construction of Concave Hull of Set of Points in R2

Authors:

Jiju P1 and M Ramanathan2

1Department of Engineering Design, IIT, [email protected] 2Department of Engineering Design, IIT, [email protected]

Abstract:

Given a set of planar points, construction of the concave hull is a problem which has not caught much

attention in Computational Geometry except in the recent past. Even though a considerable amount of

work has been devoted to address similar problems, none of them gives a precise and generic definition

which leads to an unambiguous representation of the concave hull of a set of points. All of them are

rather centered on the notion of the concave hull in a specific application perspective. In this paper, we

define the concave hull of a set of planar points as minimal perimeter simple polygon which passes

through all points. We describe an algorithm for concave hull generation based on the Geometric

Traveling Salesman Tour, which is a well known combinatorial problem in graph theory. Implementation

results shows that the algorithm always returns a unique representation for concave hull for any set of

asymmetric points.

Keywords:

concave hull, geometric traveling salesman problem, point sets


Paper 149

Title:

Ergonomic Design through Virtual Humans

Authors:

Giorgio Colombo1, Daniele Regazzoni2, Caterina Rizzi3

1Politecnico di Milano, Italy, [email protected] 2University of Bergamo, Italy, [email protected] 3University of Bergamo, Italy, [email protected]

Abstract:

Human factors are involved in several steps of product life (design, manufacture, maintenance, etc.) and

the capability to keep them into account effectively is a key point for a winning product on the market.

The rapidly spreading technology of virtual ergonomics among the CAD/CAE tools enables designers to

overcome these issues by enabling the simulation of human interaction and ergonomic behavior with a

product or system. Virtual ergonomics permits users to create and manipulate virtual humans to

investigate the interactions between the consumer or worker and the product. This paper refers to this

context and describes the use of virtual ergonomics techniques in the design process of display units

commonly used in supermarkets. The aim consists in creating a work paradigm enabling designers to

easily introduce virtual ergonomics in their everyday activities by means of a step‐by‐step procedure

based on the use of digital human modeling tool and ad‐hoc parametric products libraries.

Keywords:

Ergonomic design, Virtual Humans, refrigerated display unit, disease prevention



Paper 155

Title:

i‐Plane: a Distributed Collaborative Platform for Large Aircraft Net Engineering

Authors:

Wei Wang1, Gang Zhao2, Guangrong Yan3 and Yong Yu4

1Beihang University, [email protected] 2Beihang University, [email protected] 3Beihang University, [email protected] 4Beihang University, [email protected]

Abstract:

The large aircraft is a kind of highly complicated product. The tool software used in the large aircraft

engineering may vary from one extremity of geometry design to the other of project management. It is

important while difficult to integrate different application systems into a single platform to realize the

seamless delivery of data derived from different software. This paper presents a versatile platform

which is network‐based, distributed, and collaborative‐oriented for the large aircraft engineering. The

concept and architecture of constructing such a platform is introduced and some critical technology

problems are discussed. Finally the application of this platform is demonstrated.

Keywords:

i‐Plane; large aircraft; integration; command module


Paper 156

Title:

Research on the Elements for Internet of Things from Six Cases

Authors:

Guangrong Yan1, Wei Wang2, Gang Zhao3

1Beihang University, [email protected] 2Beihang University, [email protected] 3Beihang University, [email protected]

Abstract:

According to analysis and summing‐up of six typical cases of application of the Internet of Things, four

major elements of Internet of Things technology are summarized in this paper, namely data information

obtaining data information sending data information transmitting and data information processing. The

following conclusions are drawn from our analysis of software and hardware structure used in our six

typical cases: Under current technical condition, data information can be obtained in various ways by

the aid of internet of things technology, there are data information transmission equipment to send

data information, LAN and Internet can be used as important transmission carriers for data information

transmitting and specialized processing of data information is just the real worth place of internet of

things technology.

Keywords:

Internet of Things, data information obtaining, data information sending, data information transmitting,

data information processing


10th Annual CAD Conference June 17‐20, 2013 – Bergamo, Italy

It is a pleasure to announce that the 10th anniversary International CAD Conference and Exhibition is

planned to be held in Bergamo, Lombardy Region, Italy, June 17‐20, 2013.

Lombardy Region lies in the north of the

country, sharing a border with

Switzerland. Stretching from the Alps to the

lowlands of the Po Valley, it is home to a wide

range of landscapes, including the breath‐taking

mountain chain, the charm of the great lakes,

such as Garda Lake, Como Lake and Maggiore

Lake.

Beside Milan, the Region includes

historical and industrial cities, such

Bergamo, Brescia and others, where

history, art and culture are

harmoniously combined with

innovation, technology, fashion,

entertainment and a contemporary

outlook.

Contributions from all aspects of CAD are expected including Modeling, Analysis, High‐Performance

Graphics, Data Management, Knowledge Engineering, Collaborative Design, Reverse Engineering, and

Prototyping. Applications can be in Architecture, Bio‐ Medicine, Civil Engineering, Fashion Industry,

Industrial Design, Sustainable Energy Design, etc.

Watch the website www.cadconferences.com for updates and further information.

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