bluuebunny/crossref_metadata_2025 huggingface dataset:
Geometric Design of Uniform Developable B-Spline Surfaces
Authors: Chu Chih-Hsing , Chen Jang-Ting
Published: June 2008

This paper studies geometric design of uniform developable B-spline surfaces from two boundary curves. The developability constraints are geometrically derived from the de Boor algorithm and expressed as a set of equations that must be fulfilled by the B-spline control points. These equations help characterize the number of degrees of freedom (DOF’s) for the surface design. For a cubic B-spline surface with a first boundary curve freely chosen, five more DOF’s are available for a second boundary curve when both curves contain four control points. There remain (7-2m) DOF’s for a cubic surface consisting of m consecutive patches with C2 continuity. The results are in accordance with previous findings for equivalent composite Be´zier surfaces. Test examples are illustrated to demonstrate design methods that fully utilize the DOF’s without leading to over-constrained systems in the solution process. Providing a foundation for systematic implementation of a CAGD system for developable B-spline surfaces, this work has substantial improvements over past studies.
Integrating Freeform and Feature-Based Fitting Methods
Authors: de St. Germain H. James , Johnson David E. , Cohen Elaine
Published: June 2008

Reverse engineering (RE) is the process of defining and instantiating a model based on the measurements taken from an exemplar object. Traditional RE is costly, requiring extensive time from a domain expert using calipers and/or coordinate measurement machines to create new design drawings/CAD models. Increasingly RE is becoming more automated via the use of mechanized sensing devices and general purpose surface fitting software. This work demonstrates the ability to reverse-engineer parts by combining feature-based techniques with freeform surface fitting to produce more accurate and appropriate CAD models than previously possible.
A Systems Framework for Platform Architecture Analysis
Authors: Araque Rafael , Bailey Trevor , Bonilha Murilo W. , Fletcher Jay
Published: June 2008

This paper discusses a systems framework for platform architecture analysis. The framework considers architectural analysis at three levels; the individual product offerings within a product family, the platform(s) being leveraged across the family, and the evolution potential for the platform/product family. The framework is decomposed into elements that consider a systems perspective: function, form, concepts, interfaces, needs/goals, upstream and downstream influences, and timing/operation. An application of the framework to a transport refrigeration product family is presented as a case study. The results of this case study indicate that the framework is promising, and it continues to be developed and applied within UTC.
Moment Matching for Sensitivity Analysis of Probabilistic Model Output
Authors: Awad Mahmoud , Sudjianto Agus , Singh Nanua
Published: June 2008

With the advent of highly complex engineering simulation models that describe the relationship between input variables and output response, the need for an efficient and effective sensitivity analysis is more demanding. In this article, a generalized approach that can provide efficient as well as accurate global sensitivity indices is developed. The approach consists of two steps: running an orthogonal array based experiment using moment-matched levels of the input variables and followed by a variance contribution analysis. The benefits of the approach are demonstrated through three different examples.
Product Design Selection With Variability in Preferences for an Implicit Value Function
Authors: Maddulapalli K. , Azarm S.
Published: June 2008

Many existing selection methods require that the Decision Maker (DM) state his/her preferences precisely. However, the DM may not have enough information about the needs of end users thus causing variability in the preferences. To address this problem, we present a method for selection that accounts for variability in the DM’s preferences. Our method is interactive and iterative and assumes only that the preferences of the DM reflect an implicit value function that is quasi-concave and non-decreasing with respect to attributes. Due to the variability, the DM states his/her preferences with a range for Marginal Rate of Substitution (MRS) between attributes at a series of trial designs. The method uses the range of MRS preferences to eliminate “dominated designs” and find a set of “non-eliminated designs”. We present a heuristic to reduce the set of non-eliminated designs and obtain a set of “potentially optimal designs”. The significance of potentially optimal designs is that only one of these designs will be the most preferred for any subset of the range of MRS preferences. We present a payload design selection example to demonstrate and verify that our method indeed finds the set of potentially optimal designs.
Convergence and Stability in Distributed Design of Large Systems
Authors: Chanron Vincent , Lewis Kemper
Published: June 2008

Decentralized systems constitute a special class of design under distributed environments. They are characterized as large and complex systems divided into several smaller entities that have autonomy in local optimization and decision-making. The mechanisms behind this network of decentralized design decisions create difficult management and coordination issues. Standard techniques to modeling and solving decentralized design problems typically fail to understand the underlying dynamics of the decentralized processes and therefore result in suboptimal solutions. This paper aims to model and understand the mechanisms and dynamics behind a decentralized set of decisions within a complex design process. This paper builds on already existing results of convergence in decentralized design for simple problems to extend them to any kind of quadratic decentralized system. This involves two major steps: developing the convergence conditions for the distributed optimization problem, and finding the equilibrium points of the design space. Illustrations of the results are given in the form of hypothetical decentralized examples.
Transient Root Cause Analysis: A Model-Based Systems Engineering Methodology
Authors: Bailey Trevor , Woll Suzanne , Misra Rajul , Otto Kevin
Published: June 2008

This paper presents a model-based systems engineering methodology that can be applied to perform a root cause analysis on transient systems. The methodology extends existing root cause analysis best practice by incorporating system modeling and analysis techniques. The methodology is deployed through a detailed 5-step process to understand, identify, assess, FMEA, and validate potential transient system-level root causes. A transient performance reliability analysis for a dual mode refrigeration system is used to demonstrate how the methodology can be applied. The paper also describes a set of success factors for applying the methodology using a phased approach with a large cross-functional team.
A Weighted Three-Point-Based Strategy for Variance Estimation
Authors: Buranathiti Thaweepat , Cao Jian , Chen Wei
Published: June 2008

In manufacturing processes, it is widely accepted that uncertainty plays an important role and should be taken into account during analysis and design processes. However, uncertainty quantification of its effects on an end-product is a very challenging task, especially when an expensive computational effort is already needed in deterministic models such as sheet metal forming simulations. In this paper, we focus our work on the variance estimation of the system response. A weighted three-point-based strategy is proposed to efficiently and effectively estimate the variance of the system response. Three first-order derivatives for each variable are used to estimate the nonlinear behavior and variance of the system. The details of the derivation of the approach are presented in the paper. The optimal locations of the three points along each axis in the standard normal space and weights for input variables following normal distributions are proposed as (−1.8257,0.0,+1.8257) and (0.075,0.850,0.075), respectively. For input variables following uniform distributions U(−1,1), the optimal locations and weights are proposed as (−0.84517,0.0,+0.84517) and (0.04667,0.90666,0.04667), respectively. The proposed approach is applicable to nonlinear and multivariable systems as well as problems having no explicit function such as those design simulations based on finite element methods. The significant accuracy improvement over the traditional first-order approximation is demonstrated with a number of test problems. The proposed method requires significantly less computational effort compared with the Monte Carlo simulations. Discussions and conclusions of this work are given at the end of the paper.
Hierarchical Arrangement of Characteristics in Product Design Optimization Problems for Deeper Insight Into Optimized Results
Authors: Yoshimura Masataka , Taniguchi Masahiko , Izui Kazuhiro , Nishiwaki Shinji
Published: June 2008

This paper proposes a design optimization method for machine products that is based on the decomposition of performance characteristics, or alternatively, extraction of simpler characteristics, to accommodate the specific features or difficulties of a particular design problem. The optimization problem is expressed using hierarchical constructions of the decomposed and extracted characteristics and the optimizations are sequentially repeated, starting with groups of characteristics having conflicting characteristics at the lowest hierarchical level and proceeding to higher levels. The proposed method not only effectively enables achieving optimum design solutions, but also facilitates deeper insight into the design optimization results, and aids obtaining ideas for breakthroughs in the optimum solutions. An applied example is given to demonstrate the effectiveness of the proposed method.
Variant Design Automation: Strategy and Procedure for Storing Design Process Information
Authors: Cederfeldt Mikael
Published: June 2008

When creating a design automation system for a mature product there already exists a complete and functional product design and the task is to retrace the initial design process to find the input parameters, algorithms, rules, relations and solution strategies (design process information) that govern this initial design. This paper presents strategies and procedures for retracing, naming, classifying and storing the design process information governing the design variables of a mature product design, seen from a CAD representation perspective. Emphasis is on strategy for storing the design process information for use with the CAD representation as well as system transparency and efficient reuse of the documented and stored information.
Optimisation and Robust Design in Aero Engine Development
Authors: Karl Alexander , Lisiewicz Stephan , Friedl Winfried-Hagen , Worgan Janet , May Gordon
Published: June 2008

Recent developments in computer capabilities and software enabled the application of deterministic optimization and Robust Design methods in real world aero engine development programs. This paper describes the methods used and shows several applications of this technology. The first example is the application of a Monte-Carlo simulation to support design decisions in the HP turbine casing air system. Here the main goal was to achieve a robust design addressing the variation of build tolerances on flow areas. The variation of parameters as mass flows, pressures and temperatures based on 5000 permutations of the base model give a high confidence level for achieving reliable system behavior for a large population of engines. In addition, dependencies of result parameters on input variations indicate the main levers for system improvement. A second example is the optimization of compressor discs. Here the main emphasis was on the influence of manufacturing tolerances and on the best method to evaluate these tolerances for longer running analysis tasks. Therefore, results of a full Monte-Carlo simulation are compared with results based on two surrogate models, a response surface and a Taylor series expansion. As a final example the optimization of a HP turbine disc for which a Design of Experiment has been performed to generate a response surface model is discussed. Using the response surface data the life variability due to assumptions in the thermal modeling have been quantified and used to adjust the constraints for the subsequent deterministic optimization for weight of the HP turbine. Using deterministic optimization and especially Robust Design methods a considerable decrease in development time and cost as well as an increased product quality and reliability have been achieved. However, deterministic optimization methods alone normally drive designs on to the constraint boundaries, leading to “cliff-edge” designs. Therefore, the application of Robust Design methods is required to increase the product reliability. These methods still require a considerable computing effort, so the widespread application is just starting.
Decoupled and Single Loop Methods for Reliability-Based Optimization and Robust Design
Authors: Sopory Akhil , Mahadevan Sankaran , Mourelatos Zissimos P. , Tu Jian
Published: June 2008

Several procedures have been developed in the literature for reliability-based design optimization (RBDO), including the Reliability Index Approach (RIA), the Performance Measure Approach (PMA), and more recent techniques wherein the reliability and optimization calculations are decoupled. This paper extends the decoupled approach to include standard deviations as design parameters and wherein simulation or other methods can replace the traditional first order analytical method for reliability assessment. The methods are extended to robust design and their applicability is investigated. The paper also investigates a single loop method and extends it for the robust design problem. The accuracy and computational efficiency of the various RBDO methods are compared.
A CAD Package for High-Speed Cam Design Based on Direct Multiple Shooting Optimal Control Techniques
Authors: Mennicke Sebastian , Longman Richard W. , Chew Meng-Sang , Bock Hans Georg
Published: June 2008

High-speed automotive valve train design requires realistic models of the valve train. However, this frequently results in highly nonlinear systems with discontinuities and constraints. Optimality criteria and trade-offs for the designs are frequently performed through a process of simulation and iterative refinement. This paper presents CamOE, a cam design optimization package based on direct multiple shooting optimal control theory, incorporating structured sequential quadratic programming. The code allows the designer to incorporate the constraints of importance and to consider and synthesize appropriate optimality criteria. This allows him or her to synthesize the cam profile at the design stage without resorting to a tedious trial-and-error design process. This paper presents CamOE as a software environment that permits rapid feedback to the designer through the process of numerical experiments in specifying criteria and constraints on the automotive valve train.
A Fuzzy Dynamic Programming Approach for Mixed-Discrete Multistage Decision Processes
Authors: Xiong Ying , Rao Singiresu S.
Published: June 2008

Many engineering optimization problems can be considered as multistage decision-making problems. If the system involves uncertainty in the form of linguistic parameters and vague data, a fuzzy approach is to be used for its description. The solution of such problems can be accomplished through fuzzy dynamic programming. However, most of the existing fuzzy dynamic programming algorithms can not deal with mixed-discrete design variables in the optimization of mechanical systems containing fuzzy information. They often assumed that a fuzzy goal is imposed only on the final state for simplicity, the values of fuzzy goal and other parameters need to be predefined, and an optimal solution is obtained in the continuous design space only. To better reflect the nature of uncertainties present in real-life optimization problems, a mixed-discrete fuzzy dynamic programming (MDFDP) approach is proposed in this work for solving multistage decision-making problems in mixed-discrete design space with a fuzzy goal and a fuzzy state imposed on each stage. The feasibility and versatility of the proposed method are illustrated by considering the design of a four-bar truss. To the authors’ knowledge, this work represents the first fuzzy dynamic programming method reported in the literature for dealing with mixed-discrete optimization problems.
Application of Math-Based Marketing and Financial Tools in an Automated Parametric Design Framework
Authors: Donndelinger Joseph A. , Fenyes Peter A.
Published: June 2008

A suite of math-based marketing and financial tools has been deployed and exercised within an automated, multidisciplinary parametric design framework. This suite of tools includes a market share estimator based on Cook’s S-Model, a Technical Cost Model for estimating the variable and fixed costs of the vehicle’s body system, a database of cost estimates for other vehicle systems, and a profit estimator developed from a standard accounting template. Development of the S-Model market share estimator included completion of a Demand-Price analysis for the midsize sedan segment and collection of publicly available value curves predominantly covering the powertrain performance and interior roominess disciplines. A flexible input-output interface was developed for the Technical Cost Model to provide a means of propagating changes in body design parameters throughout the framework. A series of exercises including analysis of a baseline vehicle, optimization of a hypothetical vehicle concept for net income, and a hypothetical architectural parameter study were conducted to demonstrate the capabilities of a multidisciplinary parametric design framework enabled with marketing and financial tools. These exercises demonstrate that existing engineering and business discipline tools can effectively interoperate to design for profitability in a multidisciplinary parametric design environment. They also illustrate several key challenges in automated design for profitability, such as those encountered in defining the role of price as a design variable in a tightly coupled design-for-profit system and in generating cost estimates using a continuously variable design representation.
An Information Theoretical Perspective on Design Optimization
Authors: Krus Petter , Andersson Johan
Published: June 2008

Design optimization is becoming and increasingly important tool for design. In order to have an impact on the product development process it must permeate all levels of the design in such a way that a holistic view is maintained through all stages of the design. The design process can be viewed as a process of increasing the information of the finished product. Design optimization is on one hand a part of the design process, but can also be used as a metaphor for the whole design process. In this paper an information theoretical approach is taken to establish a performance criterion for an optimization method. Furthermore, this approach is extended do describe the design process.
A Comparative Study of Optimal Design for an Inkjet Printer Tube With and Without Performance Variations
Authors: Thielman Jeff , Ge Ping
Published: June 2008

As a new generation of printing technology, thermal inkjet (TIJ) has been widely adopted to meet the increasing demand for high printing quality and efficiency at an affordable price. High air barrier tubes play an important role in the reliable operation of the printhead in a commercial thermal inkjet printer. Desired tube qualities include low stiffness and low pressure drop, along with others. Tube stiffness and pressure drop can be lowered through the selection of proper tube layer configuration, geometry and material properties. However, the existing tube design practice is highly heuristic and design results are not optimal. Furthermore, there is no robust design consideration in the current design, and it is hard to trace and compare the tube quality from different groups of designers. In this work, a comparative study using industrial examples is conducted to search for a reusable robust design methodology for TIJ tube design. Two cases using different optimization strategies are investigated. In case A, a performance based optimization strategy is used, and the design objectives are the target performances without variation consideration. In Case B, a robust design based optimization strategy is used, and the variations of the target performances are incorporated in the design objectives. A comparison of their results with the current practice shows that the optimization strategies can greatly improve the efficiency of the current tube design process. More important, the optimization strategy with variation consideration yields robust results and provides much richer design knowledge to support designers with various experiences to make better decisions.
Reliability-Based Design Optimization Methods
Authors: Chiralaksanakul Anukal , Mahadevan Sankaran
Published: June 2008

Reliability-based design optimization (RBDO) methods are optimization algorithms that utilize reliability methods to evaluate probabilistic constraints and/or objective functions used to prescribe reliability. For practical applications, it is important that RBDO methods are efficient, i.e, they only require a manageable number of numerical evaluations of underlying functions since each one can be computationally expensive. The type of reliability methods and the manner in which they are used in conjunction with optimization algorithms strongly affect computational efficiency. The first order reliability method (FORM) and its inverse are proved to be efficient and widely accepted for reliability analysis. RBDO methods have therefore employed FORM or inverse FORM to numerically evaluate probabilistic constraints and objective functions. During the last decade, the efficiency of RBDO methods has been further improved through problem reformulation. Our goal is to present RBDO methods from a mathematical optimization perspective by formalizing FORM, inverse FORM, and associated RBDO formulations. This new perspective helps not only to clearly reveal their close relationships but also provides a common ground for understanding different types of RBDO methods. Using numerical studies reported in the literature, we indicate the numerical efficiency, convergence, and accuracy of existing RBDO methods.
Assessing Product Architecture Costing: Product Life Cycles, Allocation Rules, and Cost Models
Authors: Fixson Sebastian K.
Published: June 2008

Product families and product platforms have been suggested as design strategies to serve heterogeneous markets via mass customization. Numerous, individual cost advantages of these strategies have been identified for various life cycle processes such as product design, manufacturing, or inventory. However, these advantages do not always occur simultaneously, and sometimes even counteract each other. To develop a better understanding of these phenomena, this paper investigates the cost implications of the underlying design decision: the product architecture choice. The investigation includes factors such as product life cycle phases, allocation rules, and cost models, all of which impact the cost analysis results. Based on this investigation, directions for future research on product architecture costing are provided.
Product Platform Design Through Sensitivity Analysis and Cluster Analysis
Authors: Dai Zhihuang , Scott Michael J.
Published: June 2008

Product platform design plays a vital role in determining two important aspects of a products family: efficiency (cost savings due to commonality) and effectiveness (capability to satisfy performance requirements). In this work, sensitivity analysis and cluster analysis are used to improve both efficiency and effectiveness of a product family design. A strategy of commonization is employed to form a platform. An illustrative example is used to demonstrate the merits of the proposed method, and the results are compared with existing results from the literature.
Segmentation of Noisy Laser-Scanner Generated Meshes With Piecewise Polynomial Approximations
Authors: Vieira Miguel , Shimada Kenji
Published: June 2008

Laser scanners offer a fast and simple way of collecting large amounts of geometric data from real-world objects. Although this aspect makes them attractive for design and reverse engineering, the laser-scanner data is often noisy and not partitioned into meaningful surfaces. A good partitioning, or segmentation, of the scanner data has uses including feature detection, surface boundary generation, surface fitting, and surface reconstruction. This paper presents a method for segmenting noisy three-dimensional surface meshes created from laser-scanned data into distinct regions closely approximated by explicit surfaces. The algorithm first estimates mesh curvatures and noise levels and then uses the curvature data to construct seed regions around each vertex. If a seed region meets certain criteria, it is assigned a region number and is grown into a set of connected vertices approximated by a bicubic polynomial surface. All the vertices in a region are within known distance and surface normal tolerances from their underlying surface approximations. The algorithm works on noisy or smooth data and requires little or no user interaction. We demonstrate the effectiveness of the segmentation on real-world examples.
Solid Modeler Evaluation and Comparison Cycle: A Methodology for Optimum Selection of Modeling Software
Authors: Okudan Gu¨l E. , Rutkowski Raymond
Published: June 2008

This study proposes a methodology that would enable a design educator or a design practitioner to optimally select a solid modeling software (solid modeler) for varying objectives. Tasks accomplished to propose the methodology include: (1) reviewing past literature to compile the criteria used for selecting solid modelers, (2) preliminary comparison of a number of solid modelers on established criteria, (3) running designed experiments for comparing the user performance on predetermined solid modeling functions, and (4) compiling the experience gained as a generic methodology. The application was completed over a two-year period while a systematic selection process was undertaken at The Pennsylvania State University (Penn State). This paper documents the entire selection process including the design performance data collected. In addition the performance data, the results of the preliminary preference data are also reported. The set of outcomes of the study is expected to aid companies and design educators in making solid modeler selection decisions.
Vehicle Structure Optimization for Crash Pulse
Authors: Gu Lei , Tyan T. , Li G. , Yang R. J.
Published: June 2008

In vehicle safety engineering, it is important to determine the severity of occupant injury during a crash. Computer simulations are widely used to study how occupants move in a crash, what they collide during the crash and thus how they are injured. The vehicle motion is typically defined for the occupant simulation by specifying a crash pulse. Many computer models used to analyze occupant kinematics do not calculate both vehicle motion and occupant motion at the same time. This paper presents a framework of response surface methodology for the crash pulse prediction and vehicle structure design optimization. The process is composed of running simulation at DOE sampling data points, generating surrogate models (response surface models), performing sensitivity analysis and structure design optimization for time history data (e.g., crash pulse). Within this framework, the engineer can perform DOE sampling, surrogate modeling, main effect plot within any time interval, and design optimization. Some recent applications are presented to demonstrate how these approaches are employed for a vehicle structure design.
Graphical Modeling Environment and Supporting Framework for Function-Based Conceptual Design
Authors: Terpenny Janis P. , Mathew Deepu
Published: June 2008

As engineering products become more complicated, collaboration among multi-disciplinary design teams that are separated by location, time and across organizations is becoming an increasingly difficult task. To be effective, collaboration requires exchanging, interpreting and integrating knowledge in various locations. According to a recent study, the cost of this breakdown in knowledge in the automotive industry alone is at least $1 billion per year. There has been a significant amount of research in recent years to improve the accessibility of knowledge during design. Very little has, however, been invested in format, flow and relationships of knowledge to support the process of collaborative distributed design. Progress is particularly lagging for early stages of engineering design, conceptual design, when the need for and payoff of knowledge exchange is the greatest. This paper presents the Integrated Design Environment that is being developed at the Systems Modeling And Realization Technologies (SMART) Lab at the University of Massachusetts, Amherst. This environment facilitates knowledge flow, knowledge capture and reuse with a generalized graphical modeling environment for conceptual modeling and synthesis. The paper first provides a background in conceptual design and knowledge-based engineering followed by an architectural view of the environment and finally an example problem based on the design of a coffee maker to facilitate discussion.
A Haptic System for Virtual Prototyping of Polygonal Models
Authors: Johnson David E. , Willemsen Peter , Cohen Elaine
Published: June 2008

Virtual prototyping attempts to replace physical models with virtual models for the purpose of design evaluation. One task a virtual prototyping environment can address is the accessibility of the components of a mechanical system. In this paper, we demonstrate a haptics-based virtual prototyping system for finding collision-free paths for moving models in complex polygonal environments. The system can handle models and environments with hundreds of thousands of triangles, and augments innate human talents at searching for collision-free paths.
Influence of Group Cohesion and Information Sharing on Effectiveness of Design Review
Authors: Wetmore William , Summers Joshua D.
Published: June 2008

Research into group decision-making suggests that, dependent on the information distributed prior to a group discussion, the decision and discussion content can be predicted. While the impact to group decision-making has been studied, its impact on collaborative activities such as design review has not been well investigated. A full factorial design of experiments (3×3, DOE) is conducted to investigate the influence of group cohesion and the awareness of the presence of unshared information among group members on design review effectiveness. The results suggest that awareness may have an effect on locating design issues by representation, functional group domain, and the total amount of design issues located.
Applicability of Design Spaces to Utilize Current Assembly Plant Resources to Produce New Product Family Members
Authors: Wilmes Lindsay , Siddique Zahed
Published: June 2008

Utilizing available assembly resources can greatly reduce the development time and cost for platforms and new product family members. This paper presents a method to utilize existing assembly plant resources, during the development of new product family members, by comparing existing assembly plant with feasible assembly processes. An assembly sequence design space that can be used to perform new family member process and existing plant utilization trade-off study is presented in the paper. The assembly sequence design space is combinatorial in nature. This research seeks to provide a systematic method to represent and reason with combinatorial design spaces in which these assembly process combinations lie. Models that capture effects of constraints on these spaces, explicitly represent feasible regions, and efficiently enumerate designs within this space are investigated. Application of the assembly sequence space to perform assembly plant utilization trade-off study is demonstrated using a coffeemaker family.
A Sketch-Based Interface for the Design and Analysis of Simple Vibratory Mechanical Systems
Authors: Kara Levent Burak , Gennari Leslie , Stahovich Thomas F.
Published: June 2008

We describe a sketch-based interface designed to provide engineers with a computer environment similar to pen and paper. With our interface, users can construct functional engineering models simply by drawing sketches on a computer screen. Unlike paper sketches, however, our interface allows users to interact with their sketches in real time to modify existing objects and add new ones. To demonstrate the utility of our system, we have developed a sketch-based interface for designing and analyzing simple vibratory mechanical systems. The technical contributions of our work include: (1) a sketch parsing method for automatically locating the distinct graphical symbols in a sketch, (2) a general-purpose, trainable symbol recognizer, and (3) special purpose prerecognizers that consider shape information and make use of drawing conventions.
Haptically Guided Filtering for Reverse Engineering
Authors: Potter Kristin , Johnson David , Cohen Elaine
Published: June 2008

Reverse engineering of mechanical systems often begins with large datasets produced from laser scanning of physical artifacts. Commonly it is necessary to remove noise and filter them; however, selecting noisy regions and preserving sharp edges on desired features is difficult using standard GUI interfaces. We demonstrate a haptic interface for marking and preserving features in noisy data and for performing local smoothing operations. The force-feedback provides a natural interface for these operations.
Improved Disassembly Matrices for Disassembly Processes
Authors: Huang Yuan Mao , Liao Yu-Chung
Published: June 2008

The combined interference matrix and the combined contact matrix of product components with connection matrices, special connection relations, the disassembly sequence matrix, instability of sub-assemblies, changes of sub-assembly disassembly direction or tools, platform and the effect of gravity are investigated to obtain the optimum disassembly process. This methodology improves Huang and Huang’s method. Software is generated and two products were used as examples. Results of optimum disassembly processes were same as those obtained from other researchers. Therefore, the methodology is feasible for study of disassembly processes of products, and software can reduce the computer memory and time.
Design, Implementation and Use of a Knowledge Acquisition Tool for Sheet Metal Forming
Authors: Smith Jeremy I. , Cardew-Hall Mick , Pantano Victor , Hodgson Peter D.
Published: June 2008

Knowledge Management systems utilising a number of different techniques have been developed for manufacturing processes including sheet metal forming. These are designed to overcome knowledge loss and allow an organisation to more effectively leverage its corporate experience base. Most systems focus on design activities only, they do not capture and integrate the experience gained on the shop floor during testing and production. In order to be used in these areas, knowledge capture must be as simple and time efficient as possible, even if this is at the expense of later potential reasoning. The design, implementation and results from the use of a knowledge acquisition system of this kind for the automotive stamping industry are described. Despite perceived conceptions of data captured, it is concluded that underlying relationships can be extracted from the information entered, allowing significant reuse of captured experience, whilst maintaining timely knowledge acquisition.
Development of a Networked Haptic Environment in VR to Facilitate Collaborative Design Using Voxmap Pointshell (VPS) Software
Authors: Kim Chang E. , Vance Judy M.
Published: June 2008

A networked virtual environment is a hardware and software system where people who are geographically dispersed over the world can interact with each other by sharing space, presence, and time [1]. The goal of the work presented here is to develop methods to facilitate the use of force feedback, or haptic, devices within a networked virtual environment. Our research aims at investigating and constructing a networked haptic environment (NHE) over a non-dedicated channel for multiple users. The NHE consists of a local network between each haptic device and each virtual environment, as well as a global network linking all of the virtual environments. Position synchronization throughout the global network is accomplished using “Released-but-not-released” method (RNR) which allows computers with different performance capabilities to participate in the network without users experiencing inaccurate object motions. The networked virtual assembly application has been demonstrated using several haptic devices and several virtual environments, without a limitation on number of users or complexity of input models. Performance measures are examined and future work is outlined.
Path Generation of Mechanism Based on Multimodal Optimization Using an Evolutionary Approach
Authors: Xiao Renbin , Liu Yong , Dou Gang
Published: June 2008

This paper presents an optimization method for path generation of planar mechanisms by using artificial immune network based multimodal optimization algorithm. Firstly, the multimodal character of optimal synthesis methods for mechanism path generation is analyzed. Secondly, based on brief introduction of the artificial immune network theory and the AINET based multimodal optimization algorithm Opt-aiNet, the Opt-aiNet algorithm is improved in stopping criterion and parameter selection, which is ground on detailed analysis of the influence of parameters on the performance of algorithm. Then the improved Opt-aiNet algorithm is introduced to solve multimodal model of mechanism path generation. Finally, based upon the case study, the advantages of the improved Opt-aiNet algorithm in solving mechanism path generation problm are discussed and some concluding remarks are drawn.
Internet Design Studio
Authors: Siddique Zahed
Published: June 2008

In most instances engineering design courses are offered during the senior year of the undergraduate curriculum. These senior level design courses allow the students to apply different engineering concepts to design a product, with the expectation of preparing engineering students for a distributed and global workplace. Another possible alternative is to provide a simulated education environment where students can design products in a distributed and collaborative environment. The use of Internet in education has opened the possibility to explore and adopt new approaches to teach distributed collaborative engineering design and analysis. The Internet Design Studio, presented in this paper, tries to fulfill this need. In the Internet Design Studio each student is provided with a virtual design studio space for each project. The design studio spaces can be imagined as a virtual space containing design tools, applications, software and theoretical materials that facilitates students to design and perform analysis. Conceptually, a student enters the studio space and grabs appropriate tools to perform different design tasks. The design tools in the Internet Design Studio are web-based and support collaborations by allowing multiple users to view, discuss, create and utilize same models of the product to perform analysis. In this paper the framework of the Internet Design Studio is presented. The applicability of the framework is demonstrated through the use of several multi-designer collaborative design tools.
Asynchronous Learning of Math and Engineering Software Within the Context of a Course in Mechanisms
Authors: Freeman Robert A.
Published: June 2008

The use of interactive, web-based instructional technologies in conjunction with a course in Mechanisms for student learning of math and engineering software is described. The idea is to accomplish both the teaching of the course content and student learning of math and engineering software without taking class time to “teach” the software. The guiding principle is initially to introduce the student one step at a time through only the parts of the software necessary to solve the specific problem at hand, be it a lecture concept/learning objective or a homework assignment. Then, after the student has developed a certain familiarity with the software, they can more readily use the software’s own more encyclopedic assistive materials to address new and more comprehensive tasks. The approach taken incorporates the use of “screen capture with audio” tutorial movies, along with a variety of interactive materials including; lecture summaries, homework assignments and solutions, sample exams and exam solutions, and projects. Liberal use is also made of the software packages’ own assistive materials. The software “learned” includes MathSoft’s Mathcad and MSC’s Working Model 2D, with TechSmith’s Camtasia used to create the “screen capture with audio” tutorials. A cross-linked taxonomy of the course content and software features learned is given along with examples demonstrating the delivery and instructional techniques used.
An Interactive CAD Environment for Heterogeneous Object Design
Authors: Kou X. Y. , Tan S. T.
Published: June 2008

Traditional computer aided design (CAD) systems assume that the solids under design are homogeneous in material compositions. Recent studies have shown that solids made of heterogeneous materials (multiple materials, functionally graded materials etc.) prevail in some aspects in terms of mechanical, thermal or electrical performances. Most of the traditional CAD systems fail to represent, maintain and visualize such heterogeneous components, and there have been no commercial heterogeneous CAD modelers in the market. This paper proposes a new interactive CAD environment for heterogeneous object design, in which the geometry, topology and material information of a CAD model can be simultaneously manipulated. The functionalities of a heterogeneous CAD modeler are identified first, and a framework for heterogeneous object design is proposed. The issues of data representation, data maintenance (edition and update) and 3D visualizations are discussed. An interactive software package based on this framework—CAD4D is presented and detail examples are illustrated.
A Comparison of Two Collision Detection Libraries in a Haptic Simulation Environment
Authors: Coutee Adam S. , Bras Bert
Published: June 2008

Modeling the interaction between dynamic objects in a haptically enabled virtual environment requires high-speed collision detection. We present an independent comparison of two publicly available collision detection libraries, V-Clip and SWIFT++, as they perform in our assembly and disassembly simulation. Three assembly sequences, differing only by the complexity of the objects involved, are tested and compared based on speed of execution. In the process, some potentially limiting factors experienced while using these libraries are exposed.
An Experiment on Weight Sensation in Real and Virtual Environments
Authors: Coutee Adam S. , Bras Bert
Published: June 2008

Virtual reality allows users to visualize and interact with a three-dimensional world in a computer-generated environment. Haptic technology has allowed enhancement to these environments, adding the sense of touch through force and tactile feedback devices. In the engineering domain, these devices have been implemented in many areas including product design. We have developed a real-time simulation test bed to assess the usefulness of haptic technology for assembly and disassembly planning. In this paper, we present a study conducted to characterize the perception of weight in this virtual environment. Specifically, the experiments performed test the ability of a user to distinguish weight differences between two objects in real and virtual environments. This paper describes the experiments conducted and an analysis of the results.
Volume-Based Cut-and-Paste Editing for Early Design Phases
Authors: Masuda Hiroshi , Furukawa Yoshiyuki , Yoshioka Yasuhiro , Yamato Hiroyuki
Published: June 2008

Since product concepts are frequently changed in the early stage of design, the creation of its rough models is useful for communication among the design team. In this paper, we propose modeling operations based on a volume-based cut-and-paste method for generating rough 3D models using existing 3D models. Cut-and-paste editing extracts a characteristic feature from a source model and copies it to a target model. Our method allows pasting a wide variety of features that may have overhangs and handles, while most existing methods cannot manage such shapes. To realize such a volume-based cut-and-paste technique, this paper introduces a new method that consists of mesh segmentation and surface/volume fitting. In our method, a feature region and its surrounding area are separated from the user-specified area, and they are used for generating a parametric volume that involves the feature region. In feature pasting, parametric volumes are deformed and pasted to the target model and then features inside the volume are adaptively deformed and pasted to the target. On the basis of this cut-and-paste method, we propose modeling operations that enable feature registration, feature removal, feature pasting, and texture pasting. These operations were implemented and demonstrated using example models. The result shows our operations can effectively generate new models by removing and reusing partial shapes in existing models.
The Virtual Manufacturing Concept: Scope, Socio-Economic Aspects and Future Trends
Authors: De´pince´ P. , Chablat D. , Noe¨l E. , Woelk P. O.
Published: June 2008

The research area “Virtual Manufacturing (VM)” is the use of information technology and computer simulation to model real world manufacturing processes for the purpose of analysing and understanding them. As automation technologies such as CAD/CAM have substantially shortened the time required to design products, Virtual Manufacturing will have a similar effect on the manufacturing phase thanks to the modelling, simulation and optimisation of the product and the processes involved in its fabrication. After a description of Virtual Manufacturing (definitions and scope), we present some socio-economic factors of VM and finaly some “hot topics” for the future are proposed.
Semantically Controlled LMV Techniques for Plant Design Review
Authors: Posada Jorge , Wundrak Stefan , Stork Andre , Toro Carlos
Published: June 2008

Inspecting large industrial plants in a virtual walkthrough environment has proven to be a valuable tool in Plant Design. Many CG techniques, such as various LOD and culling methods, have been developed to visualize complex models in VR environments. These techniques decide solely based on geometric properties how to optimize the scene. In this paper we introduce the concept of semantically controlled selection of those techniques and show how semantic considerations can enhance the CAD to VR conversion process for large model visualization (LMV) walkthroughs of Plant Design models, improving the performance and adapting the visualization to the users’ needs. A taxonomy, together with semantic considerations coming from the relationship between user, model, and resources is the basis to decide which rules should be applied for a specific visualization technique. By extending a LMV walkthrough system we are able to reduce the complexity of large industrial plant models by a factor of two. On a common workplace PC the semantic preprocessing takes only 10-20 minutes for models with 106 to 107 polygons. Our approach is orthogonal to commonly known CG techniques and can be combined beneficially with those approaches.