bluuebunny/crossref_metadata_2025 huggingface dataset:
Concept for Environment Simulation at the Roller Test Bench
Authors: Albers Albert , Du¨ser Tobias , Seifermann Achim
Published: July 2009

Developing future drive systems and vehicle concepts against the background of decreasing raw material reserves and new legislation requires establishing relation between the system “vehicle” with the driver and the environment. The development of security related drive assistant systems as well as energy efficient drive strategies makes appropriate test and simulation tools necessary. Those tools must be integrated in a continuous development environment, from the individual element (e.g. control unit functions) to the entire vehicle (in the field test or roller test bench). The reproducibility of such tests in the integration of driver and environment is a great challenge. What follows is a method, which allows to integrate in the roller test bench the driver and also the environment, such as road topology and traffic, and thus to test and to develop drive assistant systems as well as energy efficient drive strategies under reproducible circumstances. For this purpose, the test environment of the acoustic test bench of the Institute of Product Development is coupled with the simulation environment AVL InMotion which enables 3D field models as well as simulating lateral dynamics to be embedded in the test bench.
A Method of Supporting Conflict Resolution for Service Design
Authors: Akiyama Yoshiki , Shimomura Yoshiki , Arai Tamio
Published: July 2009

Recently, the importance of service has been emphasized in various industries. However, few studies have focused on service design in spite of its great importance. This paper proposes a methodology for supporting service design by solving conflicts in service design solutions. The proposed methods enable service designers to discover existing conflicts in service design solutions and obtain the basic strategies to solve them using computers. The methods are verified by applying it to an existing service case.
Optimal Reference Motions With Rotation of the Feet for a Biped
Authors: Tlalolini D. , Chevallereau C. , Aoustin Y.
Published: July 2009

Fast human walking includes a phase where the stance heel rises from the ground and the stance foot rotates about the stance toe. This phase where the biped becomes under-actuated is not present during the walk of humanoid robots. The objective of this study is to determine if the introduction of this phase for a biped robot is useful to reduce the energy consumed in the walking. For simplicity only a planar biped is considered. In order to study the efficiency of this phase, four cyclic gaits are presented. For these gaits optimal motions with respect to the torque cost are defined for given performances of actuators. It is shown that for fast motions a foot rotation sub-phase is useful to reduce the criteria cost. In the optimization process, under-actuated phase (foot rotation phase), fully-actuated phase (flat foot phase) and over-actuated phase (double support phase) are considered.
Constraint Redundancy in Mobility of Parallel Manipulators
Authors: Malik Akhtar N. , Dai Jian S. , Pennock Gordon R.
Published: July 2009

This paper presents a systematic approach to obtain the degrees of freedom (DOF) of the platforms of parallel manipulators. The paper begins with general Kutzbach criterion for mobility. With simple mathematical transformations this criterion is modified to incorporate number of parallel legs used in the parallel platform-type mechanism and the number of joints in the legs. The theory of screws is used to study the freedom of the joints in the individual legs and the mobility of the platform. It is established that the general Kutzbach mobility criterion does not cater for situations where the freedom screws (or constraint screws) of the joints in a leg become dependent on the freedom screws (or constraint screws) of one or more of the other legs; thus, altering the mobility of the platform. The general modified Kutzbach mobility formula is further modified to resolve the problem of redundant constraints. The paper then provides a systematic approach towards the number synthesis of parallel platform-type mechanims. The paper includes three examples of such mechanisms analyzed by this approach. Results agree with the existing studies carried out on the mechanism used in the examples. A numerical example of a three-degree-of-freedom parallel manipulator with three legs is used to show the enumeration of all possible parallel manipulators. This includes cases with and without redundant constraints.
An Algorithm for Deriving Transition Matrix Based on Product Architecture
Authors: Kang Chang Muk , Kwak Min Jung , Cho Nam Wook , Hong Yoo S.
Published: July 2009

Economic value of the end-of-life (EOL) product largely depends on a plan of disassembly: how it should be divided into smaller subassemblies and which subassemblies should be disassembled first. To make these decisions, a disassembly structure which means all possible subassembly divisions and their disassembly paths from the bigger assemblies has to be presented in a logical form. A widely used form of presenting this kind of information is a transition matrix. In this paper, we propose an algorithm for automatic derivation of a transition matrix based on architecture of a product.
Stiffness Analysis of a 2-DoF Planar Tensegrity Mechanism
Authors: Arsenault Marc
Published: July 2009

This paper presents a general method to perform the stiffness analysis of tensegrity mechanisms. The method is based on an existing stiffness matrix model. Several stiffness indices having physical meaning are introduced. As an example, the method is applied to a planar 2-DoF tensegrity mechanism. Stiffness mappings based on the stiffness indices are generated for the mechanism’s workspace. It is shown for the example mechanism that the effect of the prestress on the stiffness is not significant when linear stiffness models of the components are assumed.
Conceptual Design of Identification Systems
Authors: Huang Yuan Mao , Liao Chung-Cheng
Published: July 2009

This is a student design project to present the procedures and the results of conceptual design for identification systems. The sub-function structure of the identification system is created after recognizing the requirement and establishing the specification. The physical effects, physical principles and solution principles are found based on the sub-functions, and the alternatives or combined solution principles are generated. The Saaty method with the modified normalized values is used to determine the relative importance or weighting factors of the standard evaluation items by paired comparisons. The eigenvalues and eigenvectors of the evaluation items and alternatives are determined. The web method is then used to determine the most preferred design of the alternatives and the best alternative is recommended. It is learned that to determine the sub-functions, the physical effects, physical principles, solution principles and combined solution principles, surveys of evaluation items, matrices of evaluation items and alternatives are very difficult, tedious and time consuming.
An Integrated Approach to Design Mechatronic Systems: Cross-Disciplinary Constraint Modeling
Authors: Chen Kenway , Panchal Jitesh , Schaefer Dirk
Published: July 2009

Mechatronic systems encompass a wide range of disciplines and hence are collaborative in nature. Currently the collaborative development of mechatronic systems is inefficient and error-prone because contemporary design environments do not allow sufficient information flow of design and manufacturing data across the electrical and mechanical domains. Mechatronic systems need to be designed in an integrated fashion allowing designers from both electrical and mechanical engineering domains to receive automated feedback regarding design modifications throughout the design process. Integrated design of mechatronic products can be realized through the integration of mechanical and electrical CAD systems. One approach to achieve this type of integration is through the propagation of constraints. Cross-disciplinary constraints between mechanical and electrical design domains can be classified, represented, modeled, and bi-directionally propagated in order to provide automated feedback to designers of both engineering domains. In this paper, the authors focus on constraint classification and constraint modeling and provide a case study example using a robot arm. The constraint modeling approach presented in this paper represents a blueprint for the actual implementation.
How Can Man and Machine Trust Each Other and Work Better Together?
Authors: Fukuda Shuichi
Published: July 2009

Our traditional machines are operated by commands. But Increasing diversification and frequent changes in our environments make it more and more difficult for a designer to foresee the operating conditions. Therefore, designs are shifting from designer-centric to user-centric, because it is a user who knows the situation and can make decisions what he or she should do. So now machines should be designed to help a user understand the current situation better and to help him or her make better decisions. They need more flexibility to work better together with its user. But there are many examples, where although a machine is equipped with a wide variety of functions to cope with almost all sorts of situations, accidents occur due to a human error. Such typical case is CFIT (Controlled Flight into terrain) [1] in airplanes. Norman pointed out that simple mechanical objects can be trusted because their behaviors are so simple people know how to operate them. But machines are getting more and more complicated so a user does not know what to expect from them. And if it does not react to his or her expectations, a user sometimes gets very much emotionally upset and gets panicked. How can we solve this problem? A solution may be found in software development. Software was produced in the past just in the same way as hardware, with their functions fixed. But now software changed its product development style. Software first provides a user with simple functions and once he or she becomes familiar with this basic level of functions, it evolves to a little higher level. Through experience and feedback from a user, software evolves its function gradually and continually. It must be noted that most of our machines are not hardware or software alone. They are combinations of both. So we can develop such a machine which possesses a diversity of functions but reveals at the very early stage of operation a basic level of functions to a user, until he or she gets accustomed to it and puts confidence in it. And when he or she fully experiences this level and desires higher level functions, then the machine evolves. How a user cope with situations varies from user to user, but if a machine is customized this way, a user would trust our machines and would operate with full confidence in them.
Improved Measurement Method for the Identification of the Centre of Gravity Location and of the Inertia Tensor of Rigid Bodies
Authors: Previati G. , Gobbi M. , Mastinu G.
Published: July 2009

The knowledge of the inertia properties of rigid bodies is of crucial importance for the correct simulation of complex mechanical systems. For this purpose at the Politecnico di Milano (Technical university of Milan) a series of test rigs have been constructed for the measurement of mass, centre of gravity location and inertia tensor of rigid bodies with masses ranging from 50 to 3500 kg. The test rigs are basically three or four bar pendulums carrying the body under investigation. The body is made to rotate around three axes passing nearby the body centre of gravity and the resulting highly non linear motion is recorded. A mathematical model simulating the motion of the body carried by the pendulum is used to identify the full inertia tensor by minimising the error between the computed and measured data. These test rigs are currently used for the identification of the mass properties of different cars, light farm tractors, engines, gearboxes and satellites. In this paper a new implementation of these test rigs is shown. By redesigning the instrumentation setup and with a new mathematical procedure for the identification, the test rigs can be used to identify the centre of gravity location and the inertia tensor with a single experimental test. In the new configuration the test rigs require a very short testing time and they are suitable for commercial development.
Design Automation Tools as a Support for Knowledge Management in Topology Optimization
Authors: Barbieri Loris , Bruno Fabio , Muzzupappa Maurizio , Cugini Umberto
Published: July 2009

The problem of integrating topological optimization tools in product development process (PDP) is becoming more and more urgent since nowadays they are widely employed in several engineering fields (civil, aeronautics, aerospace, automotive). The interest for these tools is due to their capacity to better mechanical properties through a global optimization of the product in terms of weight, stiffness, resistance and cost. In particular, there is a lack of specific tools for automatic feature recognition on voxel models generated by the topological optimization tools. Our paper presents an innovative methodology that allows the integration of topological optimizers in the product development process by means of a wise and rational knowledge management and an efficient data exchange between different systems. The target has been reached through the implementation of CAD automation modules which decrease the working time and give the possibility to effectively schematize the designer’s knowledge.
Manufacturing Experience in a Design Context Enabled by a Service Oriented PLM Architecture
Authors: C´atic´ Amer , Andersson Petter
Published: July 2009

An increased competition on the product development market pushes the industry to continually improve product quality and reduce product cost. There is also a trend towards considering a products life cycle aspects including environmental sustainability. The manufacturing process is a major cost driver in the product life cycle; hence, there are many initiatives to improve manufacturability and reduce production cost. Learning from earlier projects is essential to avoid recurrence of problems and is generally realized through use of concurrent engineering and design for manufacturing (DFM). Other research provides general DFM principles which state detailed guidelines for how different geometries combined with different manufacturing processes affect component quality and cost. The real competitive edge lies however in the development and application of company specific DFM principles that are based on manufacturing experiences. To do so requires an overview of and access to the collected manufacturing experiences. The aim of this paper is to point out key enablers for efficient reuse of manufacturing experience, which is considered to contribute to lower product cost and higher product quality. A study performed at an automotive and at an aerospace engine manufacturer pointed out the apparent need and lack of reuse of manufacturing experiences in product development. Applications supporting reuse of manufacturing experience through embedded DFM knowledge in designer’s CAD system were found in the literature. The issue of integrating these applications with the enterprise environment, in order to capitalize on existing sources of manufacturing experience, is addressed with a proposed solution applying a service oriented PLM architecture. In addition, a graphical user interface visualizing the manufacturing experience in a combined product and process context was developed. The validation of these proposed and developed solutions was done through interviews and workshops. The conclusions are that visualization of manufacturing experiences in a combined product and process context provides improved understanding of how the experiences relate to each process history and that a key enabler for integration of information in heterogeneous environments is the use of standard service oriented architectures and neutral formats.
Enabling Soft Lithography Using an Atomic Force Microscope
Authors: Johannes Matthew S. , Cole Daniel G. , Clark Robert L.
Published: July 2009

Atomic force microscope (AFM) based anodization nanolithography generates nanoscale oxide patterns on a silicon substrate in a serial fashion. The design of a custom AFM system allows for the controlled deposition of oxide patterns in the 100 nm regime. Anisotropic etching of the substrates results in raised micro- and nanostructures. The resulting master patterns are shown to be useful for the molding of stamps for soft lithographic patterning at the nanoscale. The simplicity of this method enables prototypical investigation of new materials and processes for soft lithographic research.
Piezoelectric T-Beam Microactuators
Authors: Kommepalli Hareesh K. R. , Hirsh Andrew D. , Rahn Christopher D. , Tadigadapa Srinivas A.
Published: July 2009

This paper introduces a novel T-beam actuator fabricated by a piezoelectric MEMS fabrication process. ICP-RIE etching from the front and back of a bulk PZT chip is used to produce stair stepped structures through the thickness with complex inplane shapes. Masked electrode deposition creates active and passive regions in the PZT structure. With a T-shaped crosssection, and bottom and top flange and web electrodes, a cantilevered beam can bend in-plane and out-of-plane with bimorph actuation in both directions. One of these T-beam actuators is fabricated and experimentally tested. An experimentally validated model predicts that the cross-section geometry can be optimized to produce higher displacement and blocking force.
Pultrusion Process Analysis Using Knowledge-Based System
Authors: Yu Chan , Pochiraju Kishore , Manoochehri Souran
Published: July 2009

This paper describes the development and validation of analytical and numerical procedures for the simulation of temperature and cure profiles for the pultrusion process. The governing equations for heat transfer and the resin cure reaction during pultrusion are presented and finite-difference procedure is developed to solve the governing equations. Then analytical and numerical procedures are integrated into the ACES (Automated Concurrent Engineering System) software environment. It is shown that the procedures are numerically stable and predict the temperature and cure profiles, which are in good agreement with those published by other researchers. This analysis leads to the prediction of the temperature and cure distribution along the length and through the thickness of the composite. The prediction of the temperature and cure distribution enables proper selection of process variables, which affects the production rate and quality of the parts.
Engaging High School Women in Engineering Design Using Cyberinfrastructure
Authors: English Kenneth W. , Hulme Kevin F. , Lewis Kemper E.
Published: July 2009

Without a doubt, the current generation of secondary school students is very familiar with information technology. Text messaging, e-mail, and social networking websites are a normal means of communication. There is also increasing recognition of the need for diversification the engineering workforce and increasing the number of graduating engineers in the United States. This has created an opportunity to leverage leading edge Cyberinfrastructure in an outreach program targeting secondary school students. This paper demonstrates the implementation of a targeted outreach program that engages high school students in engineering design over a two-week period using state-of-the-art digital design repositories and motion simulation equipment.
Automated Conceptual Design for Hybrid Mechanisms Based on Characteristic State Space Theory
Authors: Zhang Liping , Wang Delun , Dai Jian S.
Published: July 2009

A new methodology for automated conceptual design of hybrid combined mechanical system based on the characteristic state space approach is developed. The goal is to conceive the appropriate hybrid system given only the kinematic function posed in the problem specifications. The key enabler of the conceptual synthesis is the method of capturing kinematic behavior and transforming the continuous and non-linear motion into the discrete states and linear relation characteristic stack representation. A new characteristic state analyzing method for multi-dof primary mechanism blocks is proposed. Then the characteristic state equations are established by motion relationship between the multiple inputs and the outputs, which including characteristic transformation matrices and the characteristic state vectors established through the method of linearization for kinematic equations according to the specific input and output motion transformation. Thus the multi-dof primary mechanism blocks are identified, classified and represented qualitatively from characteristic perspectives. And then, generalized characteristic state modeling method is used to describe the behavior of the multi-loop combined mechanism. The generalized characteristic state model sets are established according to the classified primary combination patterns. The mathematical model of the hybrid combination system facilitates the characterization of the primary mechanism blocks and primary combination patterns, transformation of problem specifications, decomposition into sub-problems, and the ability to search for alternate solutions. The characteristic state space graph theory and the space vector routing model between the random input-output dual vectors in state space are established. Furthermore, with the manipulation of the dual vectors, the mathematic synthesis model is presented leading to the characteristic equation operation and the groundwork is laid for the conceptual design. To fine present the automated decomposition and the synthesis algorithm, the suggested design examples are compact and compatible with the general design principles.
Aiding Design Decision Making: Adapting Mathematical Paradigms to Fit Designers’ Actual Needs
Authors: Hayes C. C. , Akhavi F.
Published: July 2009

When designing products, designers compare complex alternatives and select one or more for further development. The quality of these selection decisions directly impacts the quality, cost and safety of the final product. Decision theoretic approaches for making systematic comparisons might help in this process, yet designers do not tend to use them. The goals of this work are to begin understanding why, and to identify future questions that may lead to solutions. This paper summarizes the results of two studies, 1) an ethnographic study of working designers in which their actual practices and needs were observed during decision making, and 2) a laboratory study in which designers were asked to use mathematical models to compare and select design alternatives. Based on these studies, we conclude that the mathematical models, as formulated, are not well suited to designers’ needs. We propose a research agenda that may lead to new approaches combining decision theoretic and user-centered methods to create tools that the average designer will be willing to use.
Dimensional Synthesis and Constrained Motion Interpolation for Planar and Spherical 6R Closed Chains
Authors: Purwar Anurag , Jin Zhe , Ge Qiaode Jeffrey
Published: July 2009

In the recent past, we have studied the problem of synthesizing rational interpolating motions under the kinematic constraints of any given planar and spherical 6R closed chain. This work presents some preliminary results on our initial attempt to solve the inverse problem, that is to determine the link lengths of planar and spherical 6R closed chains that follow a given smooth piecewise rational motion under the kinematic constraints. The kinematic constraints under consideration are workspace related constraints that limit the position of the links of planar and spherical closed chains in the Cartesian space. By using kinematic mapping and a quaternions based approach to represent displacements of the coupler of the closed chains, the given smooth piecewise rational motion is mapped to a smooth piecewise rational curve in the space of quaternions. In this space, the aforementioned workspace constraints on the coupler of the closed chains define a constraint manifold representing all the positions available to the coupler. Thus the problem of dimensional synthesis may be solved by modifying the size, shape and location of the constraint manifolds such that the mapped rational curve is contained entirely inside the constraint manifolds. In this paper, two simple examples with preselected moving pivots on the coupler as well as fixed pivots are presented to illustrate the feasibility of this approach.
Topological Consistency in Skeletal Modeling With Convolution Surfaces
Authors: Ma Guohua , Crawford Richard H.
Published: July 2009

A skeletal model consists of a collection of geometric primitives, such as points, lines, and triangles, that specifies the topology of an object. The skeleton is can be used to define surfaces, resulting in a solid model of the object. Of the various surface models that have been used for skeletal models, the convolution surface has some attractive properties. The convolution surface is an implicit surface that has been formulated for various geometric primitives such as lines, triangles, etc. Modeling with convolution surfaces guarantees a continuous and smoothly blended surface that is relatively easy to deform and intuitive to specify. However, when two skeleton elements are placed close to each other, unwanted blending can occur and the topology of the final shape becomes difficult to control. To be useful in conceptual engineering design, a skeletal modeler must ensure that the topology of surfaces generated agrees with that of the skeleton. Ensuring a match between the topology of the convolution surface and its skeleton is a challenging problem. In this paper, we propose a method based on Morse theory for ensuring topological consistency. By adjusting the parameters of the convolution surfaces, the topology of the final composite surface can be forced to match its root skeleton.
Composing Tradeoff Models for Multi-Attribute System-Level Decision Making
Authors: Malak Richard J. , Tucker Lina , Paredis Christiaan J. J.
Published: July 2009

In this paper, we study the prospects for modeling a system by composing tradeoff models of its components. A tradeoff model is an abstract representation of a system in terms of a predictive relationship between its top-level attributes. Designers can use this to predict the attributes they would achieve if they implemented the system. Prior approaches to generating tradeoff information are incompatible with model composition due to their reliance on classical Pareto dominance. We show that by using a generalization of this, called parameterized Pareto dominance, designers can produce tradeoff models that they can compose validly. The focus of this paper is on analyzing the modeling approach mathematically. The main result is proof that, under mild assumptions about how component-level attributes relate to system-level attributes, the approach is mathematically sound from a decision-theoretic perspective. The paper also includes a demonstration of the approach on the design of a hydraulic log splitter system using hydraulic component tradeoff models based on data about commercially-available components.
Optimization of a Hydraulic Mixing Nozzle
Authors: Engelbrecht Joshua J. , McCorkle Douglas S. , Ashlock Daniel A. , Bryden Kenneth M.
Published: July 2009

In industry, mixing tanks are used to homogenize two or more different products that have been combined. This work investigates the use of computational fluid dynamics (CFD) to seek an enhanced design for a hydraulic mixing nozzle. This paper outlines a method for a numerical specification of a nozzle design and generation of a CFD model to analyze it. Characteristics that influence jet distance and trajectory, such as horn size, shape, and entrainment area, are reviewed. The relative importance of each of these traits and which traits have the most significant impact on the quality of a given design are explored. Suggestions for nozzle design are summarized. This information allows the most limiting factors of a tank mixing design to be mitigated to the largest extent possible. Currently industry uses magnification ratio (the ratio of flow out of the nozzle divided by the forced flow through the nozzle jet) for mixing tank nozzle design. This paper illustrates that using magnification ratio or velocity alone does not result in an optimized design. These factors must be weighted to obtain a design that balances these factors to mix the geometry of fluid volume. Additionally, this work shows that nozzle placement is perhaps more significant than nozzle design for optimum mixing with minimum power consumption.
Making Connections Between Service and Engineering in K-12 Education
Authors: Pinnell Margaret , Blust Rebecca , Brahler Jayne , Stevens Margy
Published: July 2009

This paper will summarize the findings obtained through the work of a National Science Foundation (NSF) sponsored grant entitled, “Making Connections: Resources for K-12 Service-learning and Experiential Learning in STEM Disciplines.” The objective of this grant was to encourage K-12 educators to incorporate service-learning into the science and math curriculum by providing an easy-to-use resource. It was hoped that the use of service-learning in the science and math curriculum would help promote the entry of women and minorities into the Science, Technology, Engineering and Mathematics (STEM) fields, increase the potential pool of engineers and scientists in the United States, contribute to the development of STEM educators and enhance cultural sensitivity, ethics and social responsibility in future STEM workers. The methodology used to develop, assess and refine the web based resource will be discussed. Additionally, the research design and inferential statistics used to assess the impact of service-learning on K-12 students’ perceptions of STEM careers will be presented.
Experimental Stress Measurement Using PhotoStress-Plus: Engine Flywheel Case-Study
Authors: Tongele Tongele , Mohammed Abdul
Published: July 2009

This paper presents PhotoStress-Plus, an optical photoelastic stress analysis equipment and technique, which provides an experimental estimation of stress distribution in structural components subjected to static or dynamic loading. The construction, working principle and evaluation procedure for complete stress determination is described. Using an engine flywheel as a case-study, it is found that PhotoStress-Plus in conjunction with computational or numerical stress analysis method can provide a solid and accurate understanding of stress patterns within a loaded body.
Object Ontology With Justification Graphs for Form-Function Reasoning
Authors: Wang Eric , Kim Yong Se
Published: July 2009

We present an ontology of objects, relations among objects, and generic shape representation that supports form-function reasoning. By reasoning from the generic functions of objects to their geometric shape requirements, we deduce the generic shape representation of everyday objects. This is a complex kind of reasoning that combines diverse knowledge sources and principles. We model the results of this reasoning process as a justification graph of individual reasoning steps, which explicitly links the attributes of objects and their relations to the corresponding geometric shape elements. This object ontology uses OWL Full metamodeling techniques to achieve the necessary level of expressiveness while maintaining a generic representation. We give an example for the Table class, showing its decomposition into functions, features, and relations, and its form-function reasoning process.
Prediction of the Lower Extremity Muscle Forces During Stair Ascent and Descent
Authors: Selk Ghafari Ali , Meghdari Ali , Vossoughi Gholam Reza
Published: July 2009

An inverse dynamics musculoskeletal model of the lower extremity was combined with an optimization technique to estimate individual muscular forces and powers during stair ascent and descent. Eighteen Hill-type musculotendon actuators per leg were combined into the eleven functional muscle groups based on anatomical classification to drive the model in the sagittal plane. Simulation results illustrate the major functional differences in plantar flexors of the ankle and extensors of the knee and hip joints during ascent and descent. The results of this study not only could be employed to evaluate the rehabilitation results in the elderly but also could be used to design more anthropometric assistive devices with optimum power consumption.
Assembly and Variety Considerations During Conceptual Design
Authors: Gupta Saraj , Okudan Gu¨l E.
Published: July 2009

Foremost step in the development of any electromechanical product is its design, and conceptual design is the most ambiguous and creative phase of design. There exist only a few computational tools that aid designers at conceptual design stage, and mostly designers rely on personal experience or experience of co-workers to generate quality designs. The proposed framework aims at generating robust computerized conceptual designs by incorporating Modularity, Design for Assembly (DFA) and Design for Variety (DFV) principles at the conceptual stage. Conceptual design alternatives obtained from the proposed framework are ranked based on minimum assembly time, and are composed of modules in a way that future changes in customer needs are satisfied only by replacing certain modules. The framework involves searching a design repository of components by using functional-basis and pre-defined graph grammar rules, to generate all possible conceptual design alternatives. These design alternatives are ranked and filtered using a DFA index, and top two alternatives are selected. Selected designs are modularized and filtered using a DFV index to obtain the best design alternative. This paper provides a detailed discussion of the proposed framework, and its working is illustrated through the design of a mounting system for holding a Variable Message Sign (VMS).
A Distributed Self-Deployment Algorithm Suitable for Multiple Nonholonomic Mobile Robots
Authors: Zhou Yu
Published: July 2009

This paper introduces a novel distributed algorithm for deploying multi-robot systems, consisting of mobile robots with onboard sensing and wireless communication of limited ranges, to approach the desired sensory coverage while maintaining communication connection over targeted 2D environments. A virtual potential energy is defined for each mobile robot according to the difference between the actual and desired configurations in the neighborhood of the robot, which generates the actuating force to move the robot towards the desired local coverage. The Rayleigh’s dissipation function is adopted to provide the necessary damping mechanism which maintains the stability of the deployment motion for each robot. The equation of deployment motion for each mobile robot is then derived from the Hamilton’s principle using the method of the variational calculus, which defines the movement of the robot to approach the desired local configuration. The formulation of the variational calculus also provides a convenience way to incorporate the nonholonomic constraint arising in wheeled robots. Since the equation of deployment motion for each robot depends on only the robot’s own kinematic state and its detectable positional relationship with nearby objects, the proposed algorithm decentralizes the multi-robot deployment problem into the motion control of individual robots. Simulation results show the feasibility of the proposed approach in guiding the deployment of multi-robot systems.
Choice Model Specification in Market-Based Engineering Design
Authors: Donndelinger Joseph A. , Robinson Jeffrey A. , Wissmann Luke A.
Published: July 2009

The application of market demand models in engineering design is now a well-established practice. One could consider the archetypical application to be a random utility model used in conjunction with a parametric design representation to optimize the design of a single product with respect to a risk-adjusted measure of profit. Much of the work in this area over the past decade has been focused on various extensions of this archetypical framework, such as problem decomposition and product family design. A wide variety of market demand models have been applied, including models derived from classic economic methods and random utility models spanning from multinomial logit through generalized extreme value to mixed logit. While there has been some discussion of the properties of the various choices of market demand models used in prior work, the most recent work in this area suggests that the consequences of market demand model specification in engineering design problems are both more significant than once realized and not yet fully understood. In this paper, we explore the consequences of market demand model specification specifically in the context of engineering design through both a review of prior work and an illustrative example problem featuring a market demand model parameterized in terms of reservation price. These results demonstrate that choices in market demand model specification — especially those relating to representation of customer heterogeneity — can lead to substantially different conclusions in a discrete product configuration design problem.
Implementing a Neural Network System to Solve the Inverse Kinematics of a Biologically Inspired Robotic Cat Leg
Authors: Crawford Anthony L.
Published: July 2009

A neural network capable of solving the inverse kinematics of a four degree of freedom biologically inspired robotic cat leg (qualified as a serial linkage system) within its effective 3-D workspace is presented in this paper. The workspace consists of layers of similar but highly nonlinear cells whose vertices are associated with known kinematic variables provided by the robotic leg. The proposed neural network uses geometric properties coupled with the desired end effecter location as the neural network inputs to locate the cell for which encapsulates the associated location. Another neuron layer utilizing activation functions trained with the Perceptron Fixed learning rule is applied to interpolate within the identified cell. The similarity associated between all of the cells allows the trained neural network to effectively be applied in solving the inverse kinematics of the entire workspace.
Development of a Probabilistic Model for Mechanistic Evaluation of Reliability of Oil Pipelines Subject to Corrosion-Fatigue Cracking
Authors: Chookah Mohamed , Nuhi Mohammad , Modarres Mohammad , Seibi Abdennour
Published: July 2009

A model structure for the corrosion-fatigue degradation phenomenon has been proposed for oil pipelines. At first, a well acknowledged model for corrosion-fatigue, such as Wei’s “Super Position Model”, was pursued as a reference. By reiterating the reference model using generic data from literature and applying Monte Carlo simulation, the simplest possible structure for the model was identified. The correlation of the proposed model with the environmental effects, such as loading stress and frequency, surrounding the pipelines were estimated. The sources of random variability emerging from many sources have been reasonably embodied into only two random variables. Yet again, the scarce of field and experimental data for this particular critical degradation phenomenon has compelled the research study to rely profoundly on generic data from open literature. Hence, the best distribution estimates for the two random variables were computed. Subsequent to number of iterations, the proposed model was modified to rather simpler form. All the proposed model forms have been cross checked against the original reference model which resulted in a satisfying agreement.
Layer Separation for Optimization of Composite Laminates
Authors: Ghiasi Hossein , Pasini Damiano , Lessard Larry
Published: July 2009

The excellent mechanical properties of laminated composites cannot be exploited without a careful design of stacking sequence of the layers. An important variable in the search of the optimum stacking sequence is the number of layers. The larger is this number, the harder as well as longer is the search for an optimal solution. To tackle efficiently such a variable-dimensional problem, we introduce here a multi-level optimization technique. The proposed method, called Layer Separation (LS), increases or decreases the number of layers by gradually separating a layer into two, or by merging two layers into one. LS uses different levels of laminate representation ranging from a coarse level parameterization, which corresponds to a small number of thick layers, to a fine level parameterization, which corresponds to a large number of thin layers. A benefit of such differentiation is an increase of the probability of finding the global optimum. In this paper, LS is applied to the design of composite laminates under single and multiple loadings. The results show that LS convergence rate is not inferior to that of other optimization techniques available in the literature. It is faster than an evolutionary algorithm, more efficient than a layerwise method, simple to perform, and it has the advantage of possibility of termination at any point during the optimization process.
A Method and Software Prototype to Support On-Line Planning on CNC Machines
Authors: Kain Andreas , Hoisl Frank , Shea Kristina
Published: July 2009

Process planning for parts made on CNC machines is usually performed in sequence and carried out without feeding back information about the fabrication process to the planning stage. Shifting planning capabilities to the machine level enables consideration of direct machine feedback. In this paper a method for feature decomposition and tool path planning for pocket milling on a 3 axis milling machine is presented. Based on standard computerized numerical control (CNC) technology, G-code is transferred to the fabrication machine whereat adaptation of processing parameters can take place within a feature. In order to enable a feedback loop from the processing to the planning stage, subfeature elements are defined. Interrelations between subsequent elements are identified and standardized with regard to the manufacturing needs to realize fully machined features. For each element a tool path is generated and translated into valid G-code. After fabrication of each subfeature element processing parameters can be improved. The presented method is implemented in a prototype software tool based on an open source CAD/CAM/CAE kernel and extends an existing open source CAM software framework.
Genetic Programming of an Artificial Neural Network for Robust Control of a 2-D Path Following Robot
Authors: Roy Anthony M. , Antonsson Erik K. , Shapiro Andrew A.
Published: July 2009

Genetic Programs that have phenotypes created by the application of genotypes comprising rules are robust and highly scalable. Such encodings are useful for complex applications such as controller design. This paper outlines an evolutionary algorithm capable of creating a controller for 2 DOF, path following robot. The controllers are embodied by Artificial Neural Networks capable of full functionality despite multiple failures.
An Investigation for the Nonlinear Effects of Squeeze Film Damping and Electrostatic Forces on the Shock Spectrum of a Capacitive Accelerometer
Authors: Ibrahim Mahmoud I. , Younis Mohammad I.
Published: July 2009

This paper presents a theoretical and experimental investigation on the effects of squeeze film damping and electrostatic forces on the shock spectrum of a capacitive accelerometer. For the theoretical part, a single-degree-of-freedom system is used to model the device. Simulation results are demonstrated in a series of shock spectra that help indicate the nonlinear effects on the motion of a MEMS device. When squeeze-film effects are absent, the electrostatic forces soften the microstructure and increase its deflection significantly. A range of shock durations was found in which the microstructure experiences pull-in (pull-in zone). Larger pull-in zones are obtained as we raise the electrostatic force. On the other hand, the presence of squeeze film highly suppresses the deflection of the microstructure in the dynamic range and has minor effects in the quasi-static range. It is found in the other case that the microstructure experiences pull-in in the quasi-static range. Simulation results are compared to experimental data, showing excellent agreement.
Statistical Prediction of Long Term Characteristics for Typhoon Induced Rainstorm and Inundation in China
Authors: Xie Botao , Han Fengting , Liu Defu , Liu Shuang , Huang Shichang , Pang Liang
Published: July 2009

Of all regular recurring natural hazards, tropical cyclones pose the most dangerous threat to the economical development and more than 250 million lives in most areas of China. It is necessary to develop effective responses to an increasingly complex set of cumulative causes and consequences from typhoon characteristics and their induced disasters. Typhoon induced rainfall and inundation disasters cause enormous damage in most coastal areas of China, such as river flood and land slide. After Comprising of several popular extreme value theories, one kind of Compound Extreme Value Distribution model (Poisson-Gumbel distribution) is applied to estimate different return level precipitation in the southeast coastal region of China in this paper. It is shown that the new model can give more reasonable and comprehensive predicted result than traditional methods.
Production and Testing of Metallurgical Clad Steel Catenary Riser Pipes
Authors: Rommerskirchen Iris , Schu¨ller Thomas , Blechinger Brigitte , Heigl Gernot
Published: July 2009

The deep-water development of oil and gas fields in water depths of more than 1.000 meters represents a major technical challenge. The reserves of a gas-crude oil-water-sand mixture under the seabed must be transported safely to the top, both from an economic and environmental point of view.
A New Wind and Wave Atlas of the Hellenic Seas
Authors: Soukissian Takvor , Prospathopoulos Aristides , Korres Gerassimos , Papadopoulos Anastassios , Hatzinaki Maria , Kambouridou Maria
Published: July 2009

The main motive for producing the “Wind and Wave Atlas of the Hellenic Seas” was the increasing demand for wave and wind data in coastal and offshore areas of the Hellenic and the adjacent seas. Furthermore, the need for an updated description of the wind and wave climate was evident, as the only available Atlas for the Hellenic Seas was produced 16 years ago and was solely based on visual observations. The hindcast data of the new Atlas have been generated by numerical models of high spatial and temporal resolution, so that the main characteristic features of the wind and wave climate are represented as precisely as possible. The data cover a 10-year period (1995–2004) and are presented in a comprehensive form as charts of the spatial distribution of specific wind and wave parameters and in the form of frequency histograms in seasonal and annual basis. Systematic measured in-situ data are also released for the first time. Based on the Atlas results, a description of the main aspects of the wind and wave climate of the Hellenic Seas is attempted. In this connection, the new Atlas could be a decision support tool for long-term operational applications.