bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards Regulatory Compliance Through PLM
Authors: Joshi Nikhil , Dutta Debasish
Published: June 2008

Increasingly stringent laws regulating the amounts of hazardous substances and recyclable content in products are placing a heavy burden on product manufacturers. While manufacturers strive to be the first to bring innovative products to the market, they need to safeguard against late design changes or penalties that might result from non-compliance. At the same time, they need to ensure that the quality of the product is maintained, and prevent undue pressure on suppliers, who have to meet targets specified by the manufacturer. This paper presents a method to utilize the enterprise-wide scope provided by modern PLM systems to account for these considerations in the early design stages during the selection of material and processing specifications for product components. The method employs the chance constrained programming technique to account for the inherent uncertainties faced during these early design stages.
Multi-Agent Form Closure Capture of a Generic 2D Polygonal Object Based on Projective Path Planning
Authors: Sharma Pankaj , Saxena Anupam , Dutta Ashish
Published: June 2008

The study of multi-agent capture and manipulation of an object has been an area of active interest for many researchers. This paper presents a novel approach using Genetic Algorithm to determine the optimal contact points and the total number of agents (mobile robots) required to capture a stationary generic 2D polygonal object. After the goal points are determined the agents then reach their respective goals using a decentralized projective path planning algorithm. Form closure of the object is obtained using the concept of accessibility angle. The object boundary is first expanded and the robots reach the expanded object goal points and then converge on the actual object. This ensures that the agents reach the actual goal points at the same time and have the correct orientation. Frictionless point contact between the object and robots is assumed. The shape of the robot is considered a circle such that it can only apply force in outward radial direction from its center and along the normal to the object boundary at the contact point. Simulations results are presented that prove the effectiveness of the proposed method.
Knowledge Model for Managing Product Variety and Its Reflective Design Process
Authors: Nomaguchi Yutaka , Taguchi Tomohiro , Fujita Kikuo
Published: June 2008

Recent manufacturers have been utilizing product families to diversify and enhance the product performance by simultaneously designing multiple products under commonalization and standardization. Design information of product architecture and family is inevitably more complicated and numerous than that of a single product. Thus, more sophisticated computer-based support system is required for product architecture and family design. This paper proposes a knowledge model for a computer-based system to support reflective process of designing product architecture and product family. This research focuses on three problems which should be overcome when product family are modeled in the computer system; design repository without data redundancy and incorrectness, knowledge acquisition without forcing the additional effort on the designer, and integration of prescriptive models to support early stages of the design process. An ontology that is a foundation of a knowledge model is defined to resolve these problems. An example of designing an air conditioner product family is shown to demonstrate the capability of the system.
Process Planning Support System Considering Product Quality
Authors: Koga Tsuyoshi , Aoyama Kazuhiro
Published: June 2008

This paper proposes a new process planning method to achieve intended product quality. The design for the product quality is achieved by total designing and planning of production process considering both good factors and bad factors that affect product quality in the production process. The representation model of quality related production knowledge that is directly used in the computational design method is proposed. The discrete quality related behavior of product in process is modeled. Input information of the proposed design method consists following information: 1) a product structure; 2) feasible operations of the production process; 3) possible quality related causalities in the production process. The design method calculates the space of quality state automatically by this method. Final output information from this method is a good production process (good operations and good sequence) that achieves the intended quality state of final product. In order to develop this production process planning method for keeping the intended quality, this paper proposes a computational representation model of the quality related information in production process. Based on the production process model, a computational recommendation algorithm of production process that can achieve the intended product quality state is developed. The representation, sharing and reuse of production knowledge and know-how are realized based on the proposed production process model. A prototype system for planning a production process without failures of final product is implemented for the purpose of examination and validation for proposed method. A practical design example of a production process planning for one component of an auto-circuit breaker is demonstrated. The methodology proposed in this research addresses: (1) how the product quality in production process should be modeled; (2) how to design good operations and a good process in production that can achieve the intended product quality; and (3) how to apply the proposed method to a practical planning problem of an actual production process.
Semantic Mapping Based on Ontology and a Bayesian Network and Its Application to CAD and PDM Integration
Authors: Lee Min-Jung , Jung Min , Suh Hyo-Won
Published: June 2008

In a Collaborative Product Commerce (CPC) environment, it is necessary that the participants in a product life cycle should share semantics of terms although they may be represented differently. In order to manage this sharing of semantics, it is necessary to recognize automatically that two terms represented differently can have equivalent semantics. To this end, a semantic mapping logic that utilizes ontology and a Bayesian Network is proposed. The proposed approach consists of three phases: character matching, definition comparisons and similarity checking. First, character matching maps two terms that have identical character strings; second, the definition comparison step compares the two terms using their ontological definitions. Finally, similarity checking evaluates the similarity between two terms using their ontological structure and the Bayesian network. This final phase consists of three steps. Firstly, it calculates similarity between two terms in terms of their character strings and ontological definitions. After this step, it constructs a Bayesian network with the paired terms based on their ontological structure. Finally, it infers whether the pairs are mapped based on the network through a probability equation. The proposed approach is also applied to the integration of the CAD and PDM systems.
Simulation Model Refinement for Decision Making Via a Value-of-Information Based Metric
Authors: Panchal Jitesh H. , Paredis Christiaan J. J. , Allen Janet K. , Mistree Farrokh
Published: June 2008

Since no simulation model is perfect, any simulation model for modeling a system’s physical behavior can be refined further. Hence, the question faced by a designer is — “How much refinement of a simulation model is adequate for a particular design problem?” To answer this question, we present a value-of-information based approach for determining the appropriate extent of refinement of simulation models. The value of additional information obtained via refinement of simulation models is measured as the difference between the maximum payoff that could possibly be achieved throughout the design space and the minimum possible payoff at the point in the design space selected using the simple model. The approach is presented using two examples — design of a pressure vessel and the design of a material.
A Process Modeling Methodology for Automation of Manual and Time Dependent Processes
Authors: Nagel Robert L. , Stone Robert B. , McAdams Daniel A.
Published: June 2008

Traditional functional modeling methodologies tend to look at the decomposition of a physical artifact, system, or subsystem, but these techniques are just as applicable to processes, manual operations, and human-centric procedures. A process, when decomposed into its most basic tasks and events, resembles the products traditionally modeled using functional modeling. The aim of this paper is to present a methodology to model such processes utilizing functional modeling techniques. Process models allow for the mapping of an operation to ensure desired outputs are achieved at specific times (or after certain time durations), goals are met, critical paths are followed, and efficiency is increased. The proposed process modeling methodology is further explored as a tool to understand and identify what elements of a manual or human centric process may be automated or solved by some other engineering solution.
Bistable Compliant Four-Bar Mechanisms With a Single Torsional Spring
Authors: Mavanthoor Adarsh , Midha Ashok
Published: June 2008

Significant reduction in cost and time of bistable mechanism design can be achieved by understanding their bistable behavior. This paper presents bistable compliant mechanisms whose pseudo-rigid-body models (PRBM) are four-bar mechanisms with a torsional spring. Stable and unstable equilibrium positions are calculated for such four-bar mechanisms, defining their bistable behavior for all possible permutations of torsional spring locations. Finite Element Analysis (FEA) and simulation is used to illustrate the bistable behavior of a compliant mechanism with a straight compliant member, using stored energy plots. These results, along with the four-bar and the compliant mechanism information, can then be used to design a bistable compliant mechanism to meet specified requirements.
A Conceptual Design Tool Based on Innovative Haptic Interfaces
Authors: Bordegoni Monica , Cugini Umberto
Published: June 2008

The paper presents the results of a research project aiming at developing an innovative framework for conceptual design of products based on innovative haptic interfaces. The framework consists of a CAD (Computer Aided Design) system enhanced with intuitive designer-oriented interaction tools and modalities. The system integrates innovative 6 degrees of freedom haptic tools for modeling digital shapes, with sweep operators applied to class-A surfaces and force computation models based on chip formation models. The system aims at exploiting designers’ skills in modeling products, improving the products design process by reducing the necessity to build several physical models for evaluating and testing the product designs. The system requirements have been defined after observing designers during their daily work and translating the way they model shapes using hands and craft tools into specifications for the modeling system and the haptic tool. The system prototype has been tested by designers who have found it intuitive and effective to use.
An Enhanced Change Modes and Effects Analysis (CMEA) Tool for Measuring Product Flexibility With Applications to Consumer Products
Authors: Keese Darren A. , Takawale Neha P. , Seepersad Carolyn C. , Wood Kristin L.
Published: June 2008

Contemporary product designers seek to create products that are not only robust for the current marketplace but also flexible for future changes, adaptations, and evolutions. This type of product flexibility is distinctive from mass customization, product architecture of singular products, and product families. The intent is to design products that intrinsically enable future changes even though such changes may not be known or planned in the current product offering. To accommodate product flexibility of this type, research advancements are needed in terms of fundamental design principles and evaluation methods for predicting and improving the flexibility of a product. This paper presents advancements in both areas. We first present the systematic enhancement of a flexibility assessment tool referred to as CMEA, Change Modes and Effects Analysis. CMEA provides the basic ability to assess the flexibility of a product, with analogous features to the well-known Failure Modes and Effects Analysis. Our enhancements extend the method to provide for intuitive and more repeatable measures of flexibility. We then use the enhanced CMEA to investigate a variety of consumer products with the goal of inductively deriving product flexibility principles. Concrete applications are shown for these principles from the domain of power yard tools, such as hedge trimmers, weed trimmers, and leaf blowers. Also, the applications are used to demonstrate the value of the CMEA enhancements.
A Model of Collaborative Design Decision Making Using Timed Petri-Net
Authors: Chen Zhiqiang , Siddique Zahed
Published: June 2008

This paper presents a Petri-net process model that captures the dependency relationships of design decision making and information exchanges among multiple design problems in a distributed environment. The Model of Distributed Design (MDD) allows quantitative representation of a collaborative design process in which designers from multiple disciplines can effectively work together. The MDD is developed based on the Petri-net graph, which allows various performance analysis to be performed to evaluate and improve a collaborative design process. In this paper, the compromise Decision Support Problem (c-DSP) formulation is used to describe the design problems and the Petri-net is utilized to explicitly describe the propagation of shared design variables and the interactions. The applicability of the model is demonstrated through an example design problem that requires collaboration among four design disciplines. The design processes based on the example are modeled and then analyzed to obtain process features and performance evaluations. Based on the analysis results, an improved design process is given which shortens the design time.
A Function-Based Methodology for Analyzing Critical Events
Authors: Hutcheson Ryan S. , McAdams Daniel A. , Stone Robert B. , Tumer Irem Y.
Published: June 2008

The objective of this research was to develop a function-based method for analyzing the critical sequences of events that must occur for complex space missions to be successful. The resulting methodology, the Function-based Analysis of Critical Events, or FACE, uses functional and event models to identify the changes in functionality of a system as it transitions between critical mission events. Two examples are presented that detail the application of FACE to prior mission failures including the loss of the Columbia orbiter and the failure of the Mars Polar Lander probe. The result of the research is a methodology that allows designers to not only reduce the occurrence of such failures but also analyze the specific functional causes of the failures when they do occur.
A Graphical Modeling Environment for Configuring Modular Product Families and Platforms
Authors: Sahin Asli , Terpenny Janis P. , Goff Richard M.
Published: June 2008

A significant amount of research has established that product platform planning is effective for the development of multiple products and management strategy for companies in today’s market. However, there are still significant challenges in planning and the realization of product families and platforms. This is particularly true for determining family and platform architectures—imperative assets in companies in order to pursue competitive advantages. It is a challenging task because individual customization of products generally competes with the goal of maximizing platform commonality. To address this challenge, this paper introduces a graphical computer-based modeling environment to support product design teams in configuring modular product families. In the modeling environment, a product family can be decomposed into its products, modules, and functions. Also, interfaces among the product components can be elaborated by defining the relationship types (fundamental, redundant, and operational). Further elaboration can be achieved by defining an appropriate set of module drivers from four different perspectives: financial, customer, design processes, and organizational culture/IT. These features facilitate modeling of a product family at multiple levels of abstraction as capturing design drivers, reasoning and goals. The application of the modeling environment is illustrated with a family of coffee-makers. It is demonstrated how the proposed modeling method offers a comprehensive representation and understanding of product family planning by integrating multiple perspectives on modular architecting. Moreover, a matrix-based analysis option is provided for design teams to view the relationships between the technical functions and the forms, and the design goals and the customer requirements in a preliminary manner.
Low-Friction Rolling-Element Gear Profile Generation Using Instant Centers and Equivalent Four-Bar Linkage
Authors: Nelson Carl A. , Szydlowski Wieslaw M. , Vogel J. Conrad
Published: June 2008

A great deal of energy is lost to friction in power-transmitting devices, especially geared mechanisms. Based on a mechanism equivalence relationship between a four-bar mechanism and a geared mechanism, a procedure is developed for generating custom gear-tooth profiles using the concept of instant centers. These tooth profiles make use of roller elements between the teeth in order to eliminate the rolling-sliding contact which occurs in typical gear meshes, thus reducing power losses. Practical applicability and design constraints are investigated and preliminary results presented.
Inverse Kinematics of Discretely-Actuated Manipulators Within a Bounded Grid Element
Authors: Kemeny Deanne C. , Cipra Raymond J.
Published: June 2008

Discretely-actuated manipulators are defined in this paper as serial planar chains of many links and are an alternative to traditional robotic manipulators, where continuously variable actuators are replaced with discrete, or digital actuators. Benefits include reduced weight and complexity, and predictable manipulation at lower cost. Challenges to using digital manipulators are the discrete end-effector positions which make the inverse kinematics problem difficult to solve. Furthermore, for a specific application position in the manipulator workspace, there may not be an actual end-effector position. This research has relaxed the inverse kinematics problem around this challenge making each application position an element of a grid in which the end effector must reach. There may be many possible end-effector positions that would reach the element goal, the solution uses the first one that is found. The inverse kinematics solution assumes the assembly configuration of the digital manipulator is already solved specifically for the application grid. The Jacobian function, normally used to solve joint velocities, can be used to identify the exact shift vectors that are used for the inverse kinematics. Three methods to solve this problem are discussed and the third method was implemented as a four-part solution that is a directed and manipulated search for the inverse kinematics solution where all four solutions may be needed. A discussion of forward kinematics and the Jacobian function in relation to digital manipulators is also presented.
Developing Multiple Diverse Potential Designs for Heat Transfer Utilizing Graph Based Evolutionary Algorithms
Authors: Muth David J. , McCorkle Douglas S. , Ashlock Daniel A. , Bryden Kenneth M.
Published: June 2008

This paper examines the use of graph based evolutionary algorithms (GBEAs) to find multiple acceptable solutions for heat transfer in engineering systems during the optimization process. GBEAs are a type of evolutionary algorithm (EA) in which a topology, or geography, is imposed on an evolving population of solutions. The rates at which solutions can spread within the population are controlled by the choice of topology. As in nature geography can be used to develop and sustain diversity within the solution population. Altering the choice of graph can create a more or less diverse population of potential solutions. The choice of graph can also affect the convergence rate for the EA and the number of mating events required for convergence. The engineering system examined in this paper is a biomass fueled cookstove used in developing nations for household cooking. In this cookstove wood is combusted in a small combustion chamber and the resulting hot gases are utilized to heat the stove’s cooking surface. The spatial temperature profile of the cooking surface is determined by a series of baffles that direct the flow of hot gases. The optimization goal is to find baffle configurations that provide an even temperature distribution on the cooking surface. Often in engineering, the goal of optimization is not to find the single optimum solution but rather to identify a number of good solutions that can be used as a starting point for detailed engineering design. Because of this a key aspect of evolutionary optimization is the diversity of the solutions found. The key conclusion in this paper is that GBEA’s can be used to create multiple good solutions needed to support engineering design.
A General Excel/VBA Computer Code for Rapid Calculation of Temperature and Product Species With C-H-O-N-S Fuels
Authors: Lilley David G.
Published: June 2008

A general calculation procedure has being developed that permits very rapid calculation of general fuel-air combustion with many parameter variations. The program calculations are via Excel/VBA with immediate graphics of the parameter effects on the results. Thus, an extensive range of parameter effects may be quickly investigated and assessed. The very-general fuel is specified by way of its C-H-O-N-S content and additional water content and the “air” by way of the volume percent of oxygen, and the other component of “air” (nitrogen and/or carbon dioxide), each specified by the user. The temperature of each inlet (fuel and “air”) is specified by the user. The methodology and computer code takes as input also the equivalence ratio. Then, results of adiabatic flame temperature are calculated along with the equilibrium product species both with and without dissociation. Alternatively, the products temperature may be specified and the heat transfer in the combustor is then calculated. The computer code is very user friendly, with automatic nested loops for parameter variation and automatic generation of graphs, which are particularly useful in assessing the particular process under consideration.
Investigating Different Approaches for Front-Loading Problem Solving in Product Development: Evidence From Engine Engineering
Authors: Ameri Farhad , Qureshi Khurshid
Published: June 2008

Front-loading problem solving is a strategy that seeks to improve product development performance by shifting the identification and solving of design problems to the earlier phases of product development process. Front-loading reduces the development time by speeding up problem solving process and eliminating the total number of problems solved in a project. Furthermore, it supports intelligent decision making through loading problem solving tasks with required pieces of knowledge. In this work, front-loading is studied from a conceptual view point. Also different approaches for front-loading are investigated and classified. To support the discussions with practical examples, front-loading in studied in the context of engine engineering.
A Stochastic Approach to Surface Reconstruction
Authors: Huang Yunbao , Qian Xiaoping
Published: June 2008

Shape reconstruction, a process to compute non-discrete mathematical shape description from discrete points, has been widely used in a variety of applications such as reverse engineering, quality inspection, and topography modeling. However, current shape reconstruction approaches, often based on deterministic techniques, face two fundamental challenges: 1) in noise handling, i.e. how to properly handle the data noise variance and outliers in order to reconstruct a robust surface; 2) in model selection, i.e. how to automatically select a surface model adapting to data cloud and to local shape change in order to avoid under-fit and over-fit. This paper aims to address these two issues by developing a novel stochastic surface reconstruction approach: multilevel Kalman filter. The core idea of this approach is to use a state-space model to relate data noise with the surface model, to adopt a multilevel surface representation to address the under-fit and over-fit issue, and to use Kalman filter to produce the optimal estimates and surface uncertainty. Experimental results from the prototype implementation demonstrate that multilevel Kalman filter produces better quality surface than the traditional least-squares method and is robust against noisy data, adapts well to shape changes in complex parts, and can handle incomplete data.
Towards Uniformly Distributed Compliance in Compliant Mechanisms: A Multi-Objective Approach
Authors: Canfield Stephen L. , Chlarson Daniel L. , Shibakov Alexander , Hull Patrick V.
Published: June 2008

Researchers in the field of optimal synthesis of compliant mechanisms have been working to develop tools that yield distributed compliant devices to perform specific tasks. However, it has been demonstrated in the literature that much of this work has resulted in mechanisms that localize compliance rather than distribute it as desired. In fact, Yin and Ananthasuresh (2003) [1] demonstrate that based on the current formulation of optimality criteria and analysis via the finite element (FE) technique, a lumped compliant device will always exist as the minimizing solution to the objective function. The addition of constraints on allowable strain simply moves the solution back from this objective. Therefore, modification to the standard optimality criteria needs to take place. Yin and Ananthasuresh [1] proposed and compared several approaches that include distributivity-based measures within the optimality criteria, and demonstrated the effectiveness of this approach. In this paper, the authors propose to build on this problem. In a similar manner, a general approach to the topology synthesis problem will be suggested to yield mechanisms in which the compliance is distributed throughout the device. This work will be based on the idea of including compliance distribution directly within the objective functions, while addressing some of the potential limiting factors in past approaches. The technique will be generalized to allow simple addition of criteria in the future, and to deliver optimal designs through to manufacture. This work will first revisit and propose several quantitative definitions for distributed compliant devices. Then, a multi-objective formulation based on a non-dominating sort and Pareto set method will be incorporated that will provide information on the nature of the problem and compatibility of employed objective functions.
Near-Earth Unmanned Aerial Vehicles: Sensor Suite Testing and Evaluation
Authors: Narli Vefa , Oh Paul Y.
Published: June 2008

This paper describes a test rig that is used to design and test sensor suites for unmanned air vehicles (UAV) operating in near-earth like environments such as forests, caves and urban canyons. The test rig employs a six degree-of-freedom gantry. Inside its workspace is a full-scale diorama of the environment. Surrounding the gantry are lamps, fans, and generators to reproduce lighting, rain and obscurants typical of such environments. A sensor pod is mounted at the gantry end-effector. The acquired data is fed into a high-fidelity math model of the real UAV. The output is then used to drive the gantry to move the sensor pod in the real world environment. The net effect is a hardware-in-the-loop system that emulates the real UAV’s motions and responses in near-Earth environments. The test rig is important because there is little to no data on sensor performance metrics of UAV in near-Earth environments.
A Multidisciplinary and Multiobjective System Analysis and Optimization Methodology for Embedding Integrated Systems Health Management (ISHM) Into NASA’s Complex Systems
Authors: Mehr Ali Farhang , Tumer Irem Y.
Published: June 2008

NASA’s future space exploration systems will include a highly complex Integrated Systems Health Management (ISHM) capability, which can detect, predict, isolate and respond to system and component failures in order to improve safety and maintainability. An ISHM system, as a whole, consists of several subsystems that monitor different components of a space mission. Due to the complex and multidisciplinary nature of designing ISHM, there seems to be a lack of formal methodologies to design an optimal (or near-optimal) ISHM for a given system of systems. In this research, we propose a new methodology to design and optimize ISHM as a distributed system with multiple interacting disciplines as well as multiple conflicting design objectives (i.e. Figures Of Merit or FOMs). This specialized multidisciplinary design approach can be used to optimize the effectiveness of ISHM systems for future NASA missions. We assume a hierarchical design protocol, where each subsystem communicates with other subsystems only in a top-down tree structure. At the top level, the overall performance of the mission consists of system-level variables, parameters, objectives, and constraints that are shared throughout the system and by all subsystems. Each subsystem will then comprise of these shared values in addition to those values that are specific to subsystems. As a specific case study, we take the example of designing an ISHM capability for X-34 reusable launch vehicle in two levels. The proposed approach, referred to as ISHM Multidisciplinary and Multiobjective System Analysis & Optimization (or ISHM MMSA&O), has a hierarchical structure to pass up or down shared values between the two levels with system-level and subsystem-level optimization routines.
Geometric Construction of Piecewise Line-Symmetric Spherical Motions Using Quaternion Biarcs
Authors: Trujillo Carlos A. , Ge Q. J.
Published: June 2008

This paper employs quaternion biarcs to interpolate a set of orientations with angular velocity constraints. The resulting quaternion curve represents a piecewise spherical line-symmetric rational motion with C1 continuity. Since a quaternion arc corresponds to the motion of the planet gear in a special spherical epicyclic gear train, each segment of the quaternion biarcs can be realized with such an epicyclic gear train. Quaternion biarcs may be used to approximate B-spline quaternion curves that represent rational spherical motions that have applications in robot path planning, CAD/CAM, mechanism design, and computer graphics.
Computer Aided Synthesis of Piecewise Rational Motions for Planar 2R and 3R Robot Arms
Authors: Jin Zhe , Ge Q. J.
Published: June 2008

This paper deals with the problem of synthesizing piecewise rational motions of an object that satisfies kinematic constraints imposed by a planar robot arm with revolute joints. The paper brings together the kinematics of planar robot arms and the recently developed freeform rational motions to study the problem of synthesizing constrained rational motions for Cartesian motion planning. Through the use of planar quaternions, it is shown that the problem of synthesizing the Cartesian rational motion of a planar 2R arm can be reduced to that of circular interpolations in two separate planes. Furthermore, the problem of synthesizing the Cartesian rational motion of a planar 3R arm can be reduced to that of circular interpolation in one plane and constrained spline interpolation in a circular ring. Due to the limitation of circular interpolation, only C1 continuous rational motions are generated. For applications that require C2 continuous motions, the paper presents a joint-space based method for generating a C2 continuous motion that approximates a given C1 rational motion of the end link.
Embedding Haptics-Enabled Virtual Tools in CAD for Training Applications
Authors: Jayaram S. , Joshi H. , Jayaram U. , Kim Y. , Kate H. , Varoz L.
Published: June 2008

This paper describes recent work completed to provide haptics-enabled virtual tools in a native CAD environment, such as CATIA V5™. This was a collaborative effort between Washington State University, Sandia National Laboratories, and Immersion Technologies. The intent was to start by utilizing Immersion’s Haptic Workstation™ hardware and supporting CATIA V5™ software at Sandia and leverage the existing work on virtual assembly done by the VRCIM laboratory at Washington State University (WSU). The key contribution of this paper is a unique capability to perform interactive assembly and disassembly simulations in a native Computer Aided Design (CAD) environment using tools such as allen and box-end wrenches with force feedback using a cyberforce™ and cybergrasp™. Equally important, it also contributes to the new trend in the integration of various commercial-off-the-shelf (COTS) systems with specific user driven systems and solutions using component-based software design concepts. We discuss some of the key approaches and concepts including: different approaches to integrating the native CAD assembly data with the virtual environment constraints data; integration of the native CAD kinematics capability with the immersive environment; algorithms to dynamically organize the assembly constraints for use in manipulation with a virtual hand for assembly and disassembly simulations; and an event-callback mechanism in which different events and callback functions were designed and implemented to simulate different situations in the virtual environment. This integrated capability of haptic tools in a native CAD environment provides functionality beyond extracting data from a CAD model and using it in a virtual environment.
Generalized Synthesis of Nonlinear Springs for Prescribed Load-Displacement Functions
Authors: Vehar Christine M. , Kota Sridhar
Published: June 2008

A spring’s nonlinear load-displacement function is described by three factors, the (i) shape function, (ii) load-range, and (iii) displacement-range. The shape function encompasses the nonlinear relationship between the load and displacement, and therefore, is the most difficult factor to match. In this paper, we present a general scheme for topology, size, and shape optimization of nonlinear springs for prescribed load–displacement shape functions, while simultaneously meeting manufacturing, space, and stress constraints. This paper presents the objective function and a novel, floating point parametric model used within a genetic algorithm optimization scheme. The nonlinear springs all undergo large deformations and are evaluated by nonlinear finite element analysis. Two examples are included to demonstrate the effectiveness of the methodology in synthesizing nonlinear springs that match a prescribed load-displacement shape function.
CAD Archives Based on OAIS
Authors: Kopena Joseph B. , Shaffer Joshua , Regli William C.
Published: June 2008

Within the past few years, there has been a steady, substantial growth of interest in “long-term” archiving of digital data. This problem is particularly acute in many branches of engineering design, where cycles of technological obsolescence in supporting tools happen much more rapidly than those of designed products. Capturing and preserving design knowledge through these cycles is a major challenge that has come to be recognized by many government, industry, and research organizations. The ability to do so has important operational, efficiency, and legal ramifications for the manufacturing industry and its customers. This paper describes this problem, presenting examples of both why it must be addressed and why it is a challenge. In particular it relates preservation of engineering data to digital archiving efforts in other domains as well as ongoing work within the engineering research community on design repositories. As is shown, long term archiving of digital design knowledge draws upon both but possesses its own unique issues. Much of this discussion is couched within the language of the ISO Open Archival Information Systems (OAIS) Reference Model, including a mapping from an existing significant design repository into the OAIS model. In this way, it is hoped that this paper will widen the discussion on digital archiving within the community of this conference as well as help connect to research in other areas.
Topology Optimization of Electrostatically Actuated Micromechanical Structures With Accurate Electrostatic Modeling of the Interpolated Material Model
Authors: Alwan Aravind , Ananthasuresh G. K.
Published: June 2008

In this paper, we present a novel formulation for performing topology optimization of electrostatically actuated constrained elastic structures. We propose a new electrostatic-elastic formulation that uses the leaky capacitor model and material interpolation to define the material state at every point of a given design domain continuously between conductor and void states. The new formulation accurately captures the physical behavior when the material in between a conductor and a void is present during the iterative process of topology optimization. The method then uses the optimality criteria method to solve the optimization problem by iteratively pushing the state of the domain towards that of a conductor or a void in the appropriate regions. We present examples to illustrate the ability of the method in creating the stiffest structure under electrostatic force for different boundary conditions.
A Benchmark Comparison of Coupled and Segregated Iterative SUPG Finite Element Formulation for Incompressible Flow
Authors: Xie Jianhui , Amano R. S.
Published: June 2008

In fluid flow and heat transfer, the finite element based fully coupling solution for all conservation equations is cost effective for most of the two dimensional, isothermal problems, but suffers in the storage and solution efficiency for large three dimensional problems. The segregated solution algorithm has been designed to address large scale simulation with avoiding the direct formulation of a global matrix. There is trade-off between performing a large number of less expensive iterations by segregated solvers compared to less number of more expensive fully coupled solvers. In this paper, a Finite Element based scheme based on preconditioned GMRES coupled algorithm and SUPG (Streamline Upwind Petrov-Galerkin) pressure prediction/correction segregated formulations have been discussed to solve the steady Navier-Stokes equations. A systematic comparison and benchmark between the segregated and fully coupled formulation has been presented to evaluate the individual benefits and strengths of the coupling and segregated procedure by studying lid-driven cavity problem and large industry application problem with respect to the system storage and solution convergence.
Design of a Statically Balanced Tensegrity Mechanism
Authors: Schenk Mark , Herder Just L. , Guest Simon D.
Published: June 2008

The combination of static balancing and tensegrity structures has resulted in a new class of mechanisms: Statically Balanced Tensegrity Mechanisms. These are prestressed structures that are in equilibrium in a wide range of positions, and thus exhibit mechanism-like properties. This paper describes the design of a prototype model of a statically balanced tensegrity mechanism based on a classic tensegrity structure.
Design of Under-Actuated Open-Chain Planar Robots for Repetitive Cyclic Motions
Authors: Agrawal Sunil K. , Sangwan Vivek
Published: June 2008

Under-actuated systems are unavoidable in certain applications. For example, a biped can not have an actuator between the foot and the ground. For industrial robots, underactuation is preferable due to cost considerations. A fully actuated system can execute any joint trajectory. However, if the system is under-actuated, not all joint trajectories are attainable. For such systems, it is difficult to characterize attainable joint trajectories analytically and numerical methods are generally used to characterize them. This paper investigates the property of differential flatness for under-actuated planar open chain robots and study its dependence on inertia distribution within the system. Once this property is established, trajectory between any two points in its differentially flat output space is feasible and can be shown to be consistent with the dynamics of the under-actuated system. It is shown that certain choices of inertia distributions make an under-actuated open-chain planar robot with revolute joints feedback linearizable, i.e., also differentially flat. Hence, both cyclic and point to point trajectories can be guaranteed with these under-actuated systems. The methodology proposed is demonstrated with an under-actuated three degree-of-freedom planar robot.
An Efficient Method for Detecting Packaging Supporting Space
Authors: Chang Ching-Jui , Gea Hae Chang
Published: June 2008

This paper presents an efficient method to generate packaging space that can be used to create molded foam. This method first reduces the number of facets presenting the product and then detects heights of supporting lines from an evenly spaced mesh grid on the bottom space of a pre-defined bounding box. The height of each supporting line is further relaxed and smoothed to form the final supporting surface. Based on the supporting surface, an STL format is created so it can be fabricated using RP machines. Three examples are presented to demonstrate this method.
Semiautomated three‐dimensional segmentation software to quantify carpal bone volume changes on wrist CT scans for arthritis assessment
Authors: Duryea J. , Magalnick M. , Alli S. , Yao L. , Wilson M. , Goldbach‐Mansky R.
Published: June 2008

Rapid progression of joint destruction is an indication of poor prognosis in patients with rheumatoid arthritis. Computed tomography (CT) has the potential to serve as a gold standard for joint imaging since it provides high resolution three‐dimensional (3D) images of bone structure. The authors have developed a method to quantify erosion volume changes on wrist CT scans. In this article they present a description and validation of the methodology using multiple scans of a hand phantom and five human subjects. An anthropomorphic hand phantom was imaged with a clinical CT scanner at three different orientations separated by a 30‐deg angle. A reader used the semiautomated software tool to segment the individual carpal bones of each CT scan. Reproducibility was measured as the root‐mean‐square standard deviation (RMMSD) and coefficient of variation (CoV) between multiple measurements of the carpal volumes. Longitudinal erosion progression was studied by inserting simulated erosions in a paired second scan. The change in simulated erosion size was calculated by performing 3D image registration and measuring the volume difference between scans in a region adjacent to the simulated erosion. The RMSSD for the total carpal volumes was for the phantom, and for the in vivo subjects. Using 3D registration and local volume difference calculations, the RMMSD was . The reader time was approximately 5 min per carpal bone. There was excellent agreement between the measured and simulated erosion volumes. The effect of a poorly measured volume for a single erosion is mitigated by the large number of subjects that would comprise a clinical study and that there will be many erosions measured per patient. CT promises to be a quantifiable tool to measure erosion volumes and may serve as a gold standard that can be used in the validation of other modalities such as magnetic resonance imaging.
Energy spectrum based calculation of the half and the tenth value layers for brachytherapy sources using a semiempirical parametrized mass attenuation coefficient formulism
Authors: Yue Ning J.
Published: June 2008

As different types of radionuclides (e.g., source) are introduced for clinical use in brachytherapy, the question is raised regarding whether a relatively simple method exists for the derivation of values of the half value layer (HVL) or the tenth value layer (TVL). For the radionuclide that has been clinically used for years, such as and , the sources have been manufactured and marketed by several vendors with different designs and structures. Because of the nature of emission of low energy photons for these radionuclides, energy spectra of the sources are very dependent on their individual designs. Though values of the HVL or the TVL in certain commonly used shielding materials are relatively small for these low energy photon emitting sources, the question remains how the variations in energy spectra affect the HVL (or TVL) values and whether these values can be calculated with a relatively simple method. A more fundamental question is whether a method can be established to derive the HVL (TVL) values for any brachytherapy sources and for different materials in a relatively straightforward fashion. This study was undertaken to answer these questions. Based on energy spectra, a well established semiempirical mass attenuation coefficient computing scheme was utilized to derive the HVL (TVL) values of different materials for different types of brachytherapy sources. The method presented in this study may be useful to estimate HVL (TVL) values of different materials for brachytherapy sources of different designs and containing different radionuclides.
Comments on shielding for dual energy accelerators
Authors: Rossi M. C. , Lincoln H. M. , Quarin D. J. , Zwicker R. D.
Published: June 2008

Determination of shielding requirements for medical linear accelerators has been greatly facilitated by the publication of the National Council on Radiation Protection and Measurements (NCRP) latest guidelines on this subject in NCRP Report No. 151. In the present report the authors review their own recent experience with patient treatments on conventional dual energy linear accelerators to examine the various input parameters needed to follow the NCRP guidelines. Some discussion is included of workloads, occupancy, use factors, and field size, with the effects of intensity modulated radiotherapy (IMRT) treatments included. Studies of collimator settings showed average values of for 6 MV and for 18 MV conventional ports, and corresponding average unblocked areas of 228 and , respectively. With an average of of the field area unblocked, this gives a mean irradiated area of for the 18 MV beam, which dominates shielding considerations for most dual energy machines. Assuming conservatively small room dimensions, a gantry bin angle of was found to represent a reasonable unit for tabulation of use factors. For conventional 18 MV treatments it was found that the usual treatment angles of 0, 90, 180, and were still favored, and use factors of 0.25 represent reasonable estimates for these beams. As expected, the IMRT fields (all at 6 MV) showed a high degree of gantry angle randomization, with no bin having a use factor in excess of 0.10. It is concluded that unless a significant number of patients are treated with high energy IMRT, the traditional use factors of 0.25 are appropriate for the dominant high energy beam.