bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the Efficiency of Protein Conformation Prediction With Energy Landscape Modification
Authors: Sapsaman Temsiri , Lipkin Harvey
Published: July 2010

Since the native conformation or the natural shape of a protein largely determines its function, a prediction of protein conformation can shorten the process of drug discovery. This prediction is an optimization search to locate a configuration associated with the global minimum energy for the molecule. Due to the complexity of the multidimensional energy landscape, the prediction process can be extensive, which leads to very long simulation run times. For example, a high-resolution structure prediction algorithm [1] refining 20,000 to 30,000 models of several 49 to 88 residue long molecules takes about 150 CPU days per molecule. This paper presents the method of modified energy landscape (MEL) that improves the efficiency of the Broyden–Fletcher–Goldfarb–Shanno (BFGS) method by 12.8% on average, and more than 30% in some cases for a representative sample of cases. Since the efficiency improvement allows the probabilistic search to cover more areas of the energy landscape, locating the global minimum is more likely. Also, in a practical protein prediction running coarse refinements on more decoys is more preferable than comprehensively refining few decoys because of the low accuracy of energy functions. Therefore, the MEL can significantly improve the protein prediction simulation even though it yields less average score improvement. The MEL is implemented in a refinement protocol in Rosetta [2].
Shapley Value Based Attribute Selection for Configurators
Authors: Wang Yue , Tseng Mitchell M.
Published: July 2010

Configurators have been generally accepted as important tools to interact with customers and elicit their requirements in the form of tangible product specification. These interactions, commonly called product configuring process, aim to find the best match between customers’ requirements and company’s offerings. Therefore an efficient configurator should take both product structure and customers’ preferences into consideration. In this paper, we present a novel iterative method of attributes selection for product configuring procedure. The algorithm is based on Shapley value, a concept used in game theory to estimate the usefulness of certain entities. It iteratively selects the most relevant attribute from the remaining attributes pool and proposes it for customers to configure. Thus it obtains customers’ specification in an adaptive manner in the sense that different customers may have different query sequences. Information content is used as the measure of usefulness. As a result, the most uncertainty can be eliminated and product development team has a better understanding of what customers want in a fix time horizon. Maximum a posteriori criterion is also exploited to give product recommendation based on the partially configured product configuration. Thus the customized 1-to-1 configuring procedure is presented and the recommendation can converge to a customer’s target with fewer interactions between the customers and designers. We also use a case of PC configurator to exemplify and test the viability of the presented method.
Analysis, Synthesis, and Experiments of Standing Up Methods for a Tripedal Robot
Authors: Morazzani Ivette M. , Hong Dennis W.
Published: July 2010

This paper presents the work addressing the issue of standing up after falling down for a novel three-legged mobile robot STriDER (Self-excited Tripedal Dynamic Experimental Robot). The robot is inherently stable when all three feet are on the ground due to its tripod stance, but it can still fall down if it trips while taking a step or if unexpected external forces act on it. The unique structure of STriDER makes the simple task of standing up challenging for a number of reasons; the high height of the robot and long limbs require high torque at the actuators due to its large moment arms; the joint configuration and length of the limbs limit the workspace where the feet can be placed on the ground for support; the compact design of the joints allows limited joint actuation motor output torque; three limbs do not allow extra support and stability in the process of standing up. This paper examines four standing up strategies unique to STriDER: three feet, two feet and one foot pushup, and spiral pushup. For all of these standing up strategies, the robot places its feet or foot at desired positions and then pushes the feet against the ground thus, lifting the body upwards. The four pushup methods for standing up were analyzed and evaluated considering the constraints such as, static stability, friction at the feet, kinematic configuration and joint motor torque limits, thus determining the suggested design and operation parameters. The motor torque trends as the robot stands up using pushup methods were investigated and the results from the analysis were validated through experiments.
Co-Simulations of Motorcycle-Rider System in Road Behaviour Simulations
Authors: Manka Michal , Moreno Giner David , Kang Jian
Published: July 2010

This paper presents the research results of the first stage of the Marie Curie Project, MYMOSA (MotorcYcle and MOtorcyclist SAfety). One of the aims of MYMOSA is increasing safety of motorcycle’s rider by better understanding of its road behaviour. It can be achieved by simulations of the motorcycle-rider system during road manoeuvres and pre-/crash scenarios. The process of the motorcycle-rider system development and initial results of the road behaviour simulations are presented. The system is divided into three separate elements: controller, motorcycle and rider’s body models. The co-simulations of motorcycle, rider and controller, are performed to determine the behaviour of the system on the road. Obtained simulation results are compared with results from the system without multibody rider’s model. During further work, kinematic and dynamic properties of the rider’s body parts will be used as inputs for crash simulations with detailed rider’s model to determine positions and severity of injuries caused by crash.
A Method and Software Tool for Automated Gearbox Synthesis
Authors: Lin Yi-shih , Shea Kristina , Johnson Aylmer , Coultate John , Pears Jamie
Published: July 2010

In today’s economy, engineering companies strive to reduce product development time and costs. One approach to assisting this goal is to introduce computer-aided methods and tools earlier in the development process. This requires providing robust design automation methods and tools that can support design synthesis and the generation of alternative design configurations, in addition to automated geometric design. A new method for automated gearbox design, tailored for integration within an existing commercial gearbox analysis tool, is described in this paper. The method combines a rule-based generative approach, based on a previous parallel grammar approach for mechanical gear systems, with domain specific heuristics and stochastic search using simulated annealing. Given design specifications that include a bounding box, the number of required speeds and their target ratios, a range of valid gearbox configurations is generated from a minimal initial configuration. Initial test results show that this new method is able to generate a variety of designs which meet the design specifications. The paper concludes with a discussion of the method’s current limitations and a description of the work currently underway to improve and extend its capabilities.
Suitability of Product Development Methods for Hybrid Products as Bundles of Classic Products, Software and Service Elements
Authors: Berkovich Marina , Leimeister Jan Marco , Krcmar Helmut
Published: July 2010

The requirements engineering of hybrid products is an important field that still has a paucity of investigation to date. This paper analyzes the suitability of product development methods for the requirements engineering (RE) of hybrid products. The strengths and shortcomings of these methods regarding hybrid products are stated and fields of improvement are derived. To successfully differentiate from competitors, classic products are no longer sufficient. Therefore, many companies offer holistic solutions to customers’ problems. These solutions consist of bundles of classic products, software and services called hybrid products or product service systems (PSS). Hybrid products are characterized by a high number of components that are developed by different disciplines, by a high degree of technological integration and by a high degree of customer-integration. Due to their unique characteristics, hybrid products need holistic handling. Especially interesting is the specification and handling of the requirements for hybrid products called requirements engineering. This phase of the development process is very important for the later success of the product. The characteristics of hybrid products were thoroughly analyzed, and requirements of the RE for hybrid products were derived. A structured literature review was carried out to find the state-of-the-art of RE in product development including common textbooks and publications on respected conferences and journals in product engineering. In total, 15 textbooks, 79 journal articles and 137 articles of conference proceedings were analyzed. This provided the state-of-the-art of RE indicating the approaches used. An important aspect of the research was the matching of these approaches to the requirements defined earlier. This resulted in a list of 13 fields of RE presenting the strengths and shortcomings of the approaches in detail from which two major fields of improvement could be derived, those which need to be addressed in practice. The results show that RE for hybrid products has special needs, particularly in interdisciplinary cooperation and customer integration. The methods for RE in product development are well elaborated upon, but need to be adapted to hybrid products. There is a need for further analysis and integration of RE into the overall development process of hybrid products, as well as further development of hybrid products in practice.
On the Application of Multi-Objective Parallel Asynchronous Particle Swarm Optimization to Engineering Design Problems
Authors: McDougall Robin , Nokleby Scott
Published: July 2010

A distributed variant of multi-objective particle swarm optimization (MOPSO) called multi-objective parallel asynchronous particle swarm optimization (MOPAPSO) is presented and the effects of distribution of objective function calculations to slave processors on the results and performance are investigated. Two benchmark examples were used to verify the capability of this implementation of MOPAPSO to match previously published results of MOPSO. The computationally intensive task of multi-objective Optimization Based Mechanism Synthesis (OBMS) was used to verify that significant performance improvements were realized through parallelization. The results show that MOPAPSO is able to match the results of MOPSO in significantly less time. The fact that MOPAPSO is distributed results in an effective optimization tool for complex multi-objective design problems.
Conceptual Design of a Chain Speed Increaser for Small Hydropower Stations
Authors: Jaliu Codruta , Saulescu Radu , Diaconescu Dorin Valentin , Neagoe Mircea
Published: July 2010

Most small hydropower stations drive trains include a gearbox to increase the speed of the turbine shaft to the generator. An increase in speed is needed because the hydro turbines shafts turn at a much lower speed than is required by most electrical generators. The range in which the input angular speed must be increased is 4–8. The speed increasers for this kind of applications must have an acceptable efficiency, reduced overall dimensions and complexity and, therefore, a reduced technological cost. The paper objective is to enlarge the base of speed increasers for small hydro stations with chain transmissions. The concept of the proposed chain transmission to be used as speed increaser is developed using a conceptual design algorithm. The algorithm is based on the VDI model and consists in the following steps: 1°. Requirements list establishment; 2° Global function establishment; 3°. Global function description by structures of sub-functions; 4°. Solving structures generation by: solving the sub-functions, sub-solutions composition and elimination of inadequate solution; 5°. The best solving structure selection by evaluation. The speed increaser function is detailed as part of a hydropower station. The sub-functions of the speed increaser are further analyzed in order to generate the solving structures. Sixteen distinct structural variants are presented in the paper. But only those structural variants, whose technical characteristics fulfill, quantitatively, the requirements, are considered as solving structures (for the speed increaser function). In order to select the solving structures, the synthesis of the sprockets teeth numbers for all the structural variants is performed and their efficiency is calculated. Then, their evaluation is made taking into account the technical-economic criteria; thus, the optimal solution that fulfils the requirements list (the principle solution) is found. The principle solution is an innovative concept of the chain speed increaser and represents an input data for the embodiment design phase.
Acceptance and Divergence From Engineering Design Procedures Implicating Knowledge Flow
Authors: Jensen Ole Kjeldal , Ahmed Saeema
Published: July 2010

When developing procedures such as tools, methods and frameworks to support the development of new products, one of the challenges is ensuring their successful implementation. This paper describes a study of the development and use of such design-procedures with primary focus on the new product development process-model, its supporting methods and handling of knowledge. Semi-structured interviews with 20 participants have been carried out to understand the use of procedures. All the interviews were conducted in a company, which develops large complex equipment for oil rigs. The findings suggest that a complex understanding of procedures and reasons for divergence needs to be adopted, where implicit as well as explicit procedures are recognised and managed. Three distinct types of implicit procedures were uncovered through the study: 1) historical implicit procedures; 2) social interpretations of explicit procedures and; 3) implicit procedures supporting needs that are not catered for by the explicit procedures. In this understanding, a procedure can be any kind of method, tool or framework used to support design engineers. Furthermore, the study discusses a variety of recommended actions, depending on the type of procedure and the reason for non-conformance. Recommendations for corrective actions are proposed and feedback from managers directly involved in developing and applying the procedures are collected, to evaluate them.
Bistable Compliant Extension Aid for a Polycentric Prosthetic Knee
Authors: Roetter Adam D. , Lusk Craig P. , Dubey Rajiv
Published: July 2010

A compliant add-on mechanism for polycentric prosthetic knees was designed to provide two additional features beyond those already provided by the knee, the additional features being a stable equilibrium position when the knee is bent for the sitting posture and a moment-rotation profile that helps prevent excessive heel rise. The mechanism, dubbed the Bistable Compliant Extension Aid (BCEA), was developed and analyzed using finite-element-analysis (FEA) software. The BCEA was shown to satisfy the design requirements, prevention of excessive heel rise and providing a stable sitting position, based on its reaction moments for knee flexions ranging between 0 and 90 degrees.
Implementation and Effect of Rubrics in Capstone Design Courses
Authors: Platanitis George , Pop-Iliev Remon , Nokleby Scott
Published: July 2010

This paper demonstrates the implementation of a two-dimensional rubric system into capstone-level design courses as the preferred method for assigning and evaluating students’ design work. The rubric is based on the ICE (Ideas, Connections, and Extensions) learning and application levels, having been expanded from the basic one-dimensional rubric into two dimensions to further resolve each rank (level of application) into skill levels of learning of a given concept (i.e., a design project element), with qualitative descriptors summarizing the requirements for each skill level versus rank coordinate in the rubric that an element is applied to justify the assigned grade. These rubrics provide guidance to students in how to address the design requirements for maximum possible marks and also assist instructors with clearly defining the design requirements. The developed rubrics are applicable to other upper year undergraduate and graduate level courses featuring a major design project with minor modifications. Their usefulness was evident in the observed improvement of students’ grades over the last three years. For capstone courses, a multi-dimensional rubric is more versatile, providing instructors with a greater choice of assigning grade levels to evaluate student performance for a given element of the design project.
The Static and Dynamic Behavior of MEMS Arches Under Electrostatic Actuation
Authors: Ouakad Hassen M. , Younis Mohammad I. , Alsaleem Fadi M. , Miles Ronald , Cui Weili
Published: July 2010

In this paper, we investigate theoretically and experimentally the static and dynamic behaviors of electrostatically actuated clamped-clamped micromachined arches when excited by a DC load superimposed to an AC harmonic load. A Galerkin based reduced-order model is used to discretize the distributed-parameter model of the considered shallow arch. The natural frequencies of the arch are calculated for various values of DC voltages and initial rises of the arch. The forced vibration response of the arch to a combined DC and AC harmonic load is determined when excited near its fundamental natural frequency. For small DC and AC loads, a perturbation technique (the method of multiple scales) is also used. For large DC and AC, the reduced-order model equations are integrated numerically with time to get the arch dynamic response. The results show various nonlinear scenarios of transitions to snap-through and dynamic pull-in. The effect of rise is shown to have significant effect on the dynamical behavior of the MEMS arch. Experimental work is conducted to test polysilicon curved microbeam when excited by DC and AC loads. Experimental results on primary resonance and dynamic pull-in are shown and compared with the theoretical results.
Bayesian Hierarchical Choice Modeling Framework for Capturing Heterogeneous Preferences in Engineering System Design
Authors: Hoyle Christopher , Chen Wei , Wang Nanxin , Koppelman Frank S.
Published: July 2010

Choice models play a critical role in enterprise-driven design by providing a link between engineering design attributes and customer preferences. In our previous work, we introduced the hierarchical choice modeling approach to address the special needs in complex engineering system design. The hierarchical choice modeling approach utilizes multiple model levels to create a link between qualitative attributes considered by consumers when selecting a product and quantitative attributes used for engineering design. In this work, the approach is expanded to the Bayesian Hierarchical Choice Modeling (BHCM) framework, estimated using an All-at-Once (AAO) solution procedure. This new framework addresses the shortcomings of the previous method while providing a highly flexible modeling framework to address the needs of complex system design. In this framework, both systematic and random consumer heterogeneity is explicitly considered, the ability to combine multiple sources of data for model estimation and updating is significantly expanded, and a method to mitigate error propagated throughout the model hierarchy is developed. In addition to developing the new choice model approach, the importance of including a complete representation of consumer heterogeneity in the model framework is provided. The new modeling framework is validated using several metrics and techniques. The benefits of the BHCM method are demonstrated in the design of an automobile occupant package.
Design of a Multi-Function Vector Bar
Authors: Domboski Kristen , McCauley Raymond , Morton Mike , Liem Andrea , Keefe Michael
Published: July 2010

The University of Delaware Department of Mechanical Engineering curriculum includes a senior design project, where teams address real design challenges facing local firms. The SURVICE Engineering Company tasked a team to design an improved metrology vector bar for use with an indoor global positioning system (iGPS) computer system. This vector bar needed to be ergonomic, easy to use, and easy to manufacture. To fulfill these requirements, metrics for a smaller, lighter, and more ergonomically designed Multi-Function Vector Bar were established. To encompass these metrics, four different subsystems were identified and integrated into a final design. Of these systems, emphasis was placed on a new ergonomic handle designed through an iterative process. New features were added to the handle to facilitate a decrease in human error and an increase in functionality. Multiple handle models were designed and tested to accomplish this. The final handle design resulted in a balanced, lighter, and more comfortable prototype that had two control buttons and indicator lights.
DSM-Based Product Representation for Retirement Process-Based Modularity
Authors: Lai Xiaoxia , Gershenson John K.
Published: July 2010

Researchers have expanded the definition of product modularity from function-based modularity to life-cycle process-based modularity. In parallel, measures of product modularity have been developed as well as corresponding modular product design methods. However, a correct modularity measure and modular design method are not enough to realize modular product design. To apply the measure and design method correctly, product representation becomes an important aspect of modular design and imperative for realizing the promised cost savings of modularity. In this paper, a representation for retirement process-based modular design has been developed. Built upon previous representations for assembly and manufacturing-based product design, the representation includes a process similarity matrix and a process dependency matrix. The retirement process-based similarity is based on the similarity in components’ post-life intents (recycling, reuse, disposal), and either the degree of their material compatibility if the components will be recycled, or their disassembly direction or disassembly tools if they need to be disassembled from each other for retirement. Process similarity within a module leads to increased process efficiency (the elimination of non-value added tasks) from the sharing of tooling/equipment. Retirement process-based dependency is developed based on disassembly difficulty, one aspect of the physical interactions between components. Retiring components together as a module to eliminate disassembly and differential processing and reducing the disassembly difficulty between the modules can increase the efficiency of the retirement process. We have first presented which process elements we should consider for defining retirement process similarity and dependency, and then constructed the respective similarity and dependency factors tables. These tables include similarity and dependency factors, which, along with their quantifications, are used to determine a product’s modular architecture to facilitate the retirement process. Finally, a fishing reel is used to illustrate how to apply these factors tables to generate the similarity and dependency matrices that represent a product for retirement-process based modular design. Using these representations as input to the DSM-based modular design methods, we can achieve a design with a modular architecture that improves the retirement process efficiency and reduces retirement costs.
Grammatical Evolution of Technical Processes
Authors: Stankovic´ Tino , Shea Kristina , Sˇtorga Mario , Marjanovic´ Dorian
Published: July 2010

In the teleological sense, people design new products in order to meet market demands and societal needs and by fulfilling these, they push the boundaries of technical evolution. These demands and needs are met by means of a technical process (TP) inside which the operands are transformed to achieve desired state. If the problem of search for suitable optimal technologies required for the operand transformation within the TP can be tackled computationally, then the transformation alternatives can be obtained in an expedient fashion with the probability of the generation of novel alternatives. The approach considered within this paper proposes a grammatical evolution (GE) based method for the search and optimization of technical processes. The breakdown of the TP as a black-box concept into a system of interrelated sub-processes and operations is done according to the formalized knowledge inside the set of production rules of the Backus-Naur form (BNF). Once the breakdown procedure has produced a state composed solely of terminals, the specification of the needed effects required for establishing the product function structure is complete. This paper presents the breakdown of the TP of tea-brewing as an example.
Supporting Trade Space Exploration of Multi-Dimensional Data With Interactive Multi-Scale Nested Clustering and Aggregation
Authors: Zhang Xiaolong Luke , Simpson Timothy W. , Frecker Mary , Lesieutre George
Published: July 2010

Knowledge discovery in multi-dimensional data is a challenging problem in engineering design. For example, in trade space exploration of large design data sets, designers need to select a subset of data of interest and examine data from different data dimensions and within data clusters at different granularities. This exploration is a process that demands both humans, who can heuristically decide what data to explore and how best to explore it, and computers, which can quickly identify features that may be of interest in the data. Thus, to support this process of knowledge discovery, we need tools that go beyond traditional computer-oriented optimization approaches to support advanced designer-centered trade space exploration and data interaction. This paper is an effort to address this need. In particular, we propose the Interactive Multi-Scale Nested Clustering and Aggregation (iMSNCA) framework to support trade space exploration of multi-dimensional data common to design optimization. A system prototype of this framework is implemented to allow users to visually examine large design data sets through interactive data clustering, aggregation, and visualization. The paper also presents a case study involving morphing wing design using this prototype system. By using visual tools during trade space exploration, this research suggests a new approach to support knowledge discovery in engineering design by assisting diverse user tasks, by externalizing important characteristics of data sets, and by facilitating complex user interactions with data.
Kineto-Static Stiffness Mapping Based on Finite Element Analysis for Robot Manipulators
Authors: Zhao Kai , Chen Genliang , Wang Hao , Zhao Yong
Published: July 2010

Nowadays, the stiffness mapping for robot manipulators is established in static condition by means of lumped stiffness model, which is not accurate enough to describe the actual deformation when the manipulator is working in extreme environment with heavy and dynamic loads. This paper presents a kineto-static stiffness mapping derived by means of the general equation of dynamics for robot manipulators, which takes into account the kinematic influence on the stiffness matrix. At each discrete point of the predefined trajectory of the end-effector, inertial forces and torques related to the kinematic parameters are introduced and flexible links are modeled by the finite element analysis (FEA) method to obtain the accurate deformation of each body. The formulation reveals that the kineto-static stiffness matrix consists of the stiffness properties of actuators, transmission mechanisms, force elements (spring and damping) and flexible links and is related to the inertial loads as well as the configuration and applied loads. A planar 3-RPR (revolute-prismatic-revolute) manipulator with flexible links is studied here as an example to show that the stiffness matrix computed by the proposed kineto-static stiffness map is both comprehensive and feasible.
A Measure of Product Sustainability Based on Triple Bottom Line
Authors: Sarkar Prabir , Rachuri Sudarsan , Suh Hyo Won , Lyons Kevin , Sriram Ram D.
Published: July 2010

Sustainable societies require the use of sustainable products. Sustainability is generally expressed in terms of Triple Bottom Line (TBL) — people, planet, and profit. Products that are sustainable have positive effects and value for all the stakeholders. In this work, we propose different measures to assess sustainability of manufactured products with respect to TBL. The proposed measures should help designers to assess sustainability of design alternatives during the initial phase of design and point out ways to reduce the impact.
The Virtual Haptic Human Upper Body
Authors: Chen Meng-Yun , Williams Robert L.
Published: July 2010

The objective of this research is to create a movable, palpable virtual model of the dynamic human upper body, including the spine, shoulders, and arms skeletal structure, with dynamic pivot point and deformable skin. This Virtual Haptic Human Upper Body (VHHUB) model has realistic human motion with anatomically-accurate joint motion limits and a 71 degrees-of-freedom branching serial chain model. The aim is to provide realistic motions when an osteopathic medical student moves the virtual patient for palpatory diagnosis training. Medical trainees can thus practice feeling changes in human tissue due to motions, a common diagnostic technique.
A Mixed Logit Choice Modeling Approach Using Customer Satisfaction Surveys to Support Engineering Design
Authors: He Lin , Hoyle Christopher , Chen Wei
Published: July 2010

Choice modeling is critical for assessing customer preferences as a function of product design attributes and customer profile information. Previous works have focused upon the use of survey data in which respondents are presented with a set of simulated product options from which they make a choice. However, such data does not represent real purchase behavior and these surveys require significant time and additional cost to administer. For these reasons, an approach to estimate a choice model using widely available customer satisfaction survey data for actual purchases is developed. Through a close examination of customer satisfaction survey data, several key characteristics are identified, including the lack of defined choice sets and missing choice attributes, the use of subjective measures such as ratings by customers to describe product attributes, multiple collinearity among many of the product attributes, and potentially insufficient attribute variation in the product designs evaluated by the respondents in the survey. A mixed logit based choice modeling procedure is developed in this paper to incorporate the use of both survey ratings as subjective measures and engineering attributes as quantitative measures in the model utility function. In order to accurately reflect choice behavior in actual market conditions, heterogeneity in customer preference is explicitly considered in the demand model. A case study using the Vehicle Quality Survey data acquired from J.D. Power and Associates demonstrates many of the key features of the proposed approach. The estimation results show the mixed logit model to be successful in modeling customer choices at the individual level, demonstrating the potential of being integrated with engineering models for engineering design.
Partial Decoupling of the Matrix Method for Planar Mechanisms Inverse Dynamics
Authors: Williams Robert L.
Published: July 2010

This paper presents a partial decoupling method for the well-known matrix method commonly in use for the linear inverse dynamics problem of planar mechanisms. Any mechanism with a dyad of binary links can benefit from the proposed method, which involves extracting submatrices by looking for sufficient columns of zeros such that a reduced problem may first be solved with an equal number of scalar equations and unknowns. Then some equal-and-opposite internal joint forces are transferred to the remaining FBDs and the solution proceeds until the input link is solved in a decoupled manner. The method leads to significant reductions in computational cost for common planar mechanisms. The kinematics & dynamics textbooks have overlooked this partial decoupling in their presentations of the matrix method for inverse dynamics.
MEMS Bandpass Filters Based on Cyclic Coupling Architectures
Authors: Chivukula Venkata Bharadwaj , Rhoads Jeffrey F.
Published: July 2010

Resonant microelectromechanical systems (MEMS) offer distinct utility in signal processing and wireless communications applications due to their comparatively-high quality factors, low power consumption, and ease of integration with existing integrated circuit (IC) technologies. While a number of efforts have previously demonstrated the use of mechanically-coupled microresonators in bandpass signal filtering applications, the vast majority of these works have emphasized the use of resonator chains coupled in an open configuration, wherein the terminating (end) elements in the array are coupled to only a single resonator and the interior resonators are coupled solely to their nearest neighbors. While this configuration suffices for many MEMS-based filter designs, it is not guaranteed to be an optimal coupling architecture. The present work explores an alternative class of MEMS bandpass filters based on cyclically-coupled, closed-chain resonator configurations and specifically examines the pertinent performance metrics (effective quality factor, shape factor, bandwidth, ripple, and maximum transmission) associated with each architecture. By varying coupling strength and the quality factor of individual resonators over wide, yet realistic, parameter ranges, regions of superior performance for both open- and closed-chain filter architectures have been observed. Of particular interest here, is the fact that preliminary results indicate that cyclically-coupled resonator configurations exhibit improved ripple metrics, reduced frequency dependence within the passband, and, generally speaking, more robustness to process-induced variations than their open-chain counterparts. As such, cyclically-coupled filter designs, with further refinement, may ultimately lead to an improved MEMS bandpass filter capability.
Flow State Logic (FSL) for Analysis of Failure Propagation in Early Design
Authors: Jensen David , Tumer Irem Y. , Kurtoglu Tolga
Published: July 2010

For safety critical complex systems, reliability and risk analysis are important design steps. Implementing these analyses early in the design stage can reduce costs associated with redesign and provide important information on design viability. In the past several years, various research methods have been presented in the design community to move reliability analysis into the early conceptual design stages. These methods all use a functional representation as the basis for reliability analysis. This paper asserts that, in non-nominal system states, the functional representation limits the scope of failure analysis. Specifically, when failures are modeled to propagate along energy, material, and signal (EMS) flows, a nominal-state functional model is insufficient for modeling all types of failures. To capture possible failure propagation paths, a function-based reliability method must consider all potential flows, and not be limited to the function structure of the nominal state. In this light, this paper introduces the Flow State Logic (FSL) method as a means for reasoning on the state of EMS flows that allows the assessment of failure propagation over potential flows that were not considered in a functional representation of a “nominally functioning” design. A liquid fueled rocket engine serves as a case study to illustrate the benefits of the methodology.
Bipedal Robot Walking Cycle Forces and Torques Prediction and an Inverse System and Gain Scheduling Based Control
Authors: Kljuno Elvedin , Williams Robert L.
Published: July 2010

This paper shows an overview of the walking model by grouping them into two large groups: the models with the concentrated mass and models with distributed mass. As an example of the models with concentrated mass, a mass-spring inverted pendulum model is shown, accompanied with a short analysis. As an example of a more complex model, a 13 DOF walking robot model is analyzed including the model kinematics, dynamics and controls accompanied with numerical solutions (simulations) for particular desired joint trajectories, recorded from a real human walking cycle. Kinematic and Dynamic analysis is discussed including results for joint torques and ground force necessary to implement the prescribed walking motion. This analysis is accompanied with a limited comparison with available experimental data. Finally, an inverse plant and tracking error linearization based controller design approach is described accompanied with results analysis and conclusions about the controller performances.
Automated Vehicle Structural Crashworthiness Design via a Crash Mode Matching Algorithm
Authors: Hamza Karim , Saitou Kazuhiro
Published: July 2010

This paper presents an automated algorithm for design of vehicle structures for crashworthiness, based on the analyses of the structural crash mode. The crash mode (CM) is the history of the deformation of the different zones of the vehicle structure during a crash event. The algorithm emulates a process called crash mode matching where structural crashworthiness is improved by manually modifying the design until its crash mode matches the one the designers deem as optimal. Given an initial design and a desired crash mode, the algorithm iteratively finds new designs that have better crashworthiness performance via stochastic sampling of the design space. A new design is chosen per iteration as the best among the normally distributed samples near the current design. The mean and standard deviation of the normal distributions are adjusted in each iteration by examining the crash mode of the current design and applying a set of fuzzy logic rules that encapsulate elementary knowledge of the crash mode matching practice. Two case studies are presented to demonstrate the effectiveness of the proposed algorithm. The case studies examine a front half vehicle model, as well as a fully detailed vehicle model.
Validating Module Heuristics on Large Scale Products
Authors: Day Rachel , Stone Robert B. , Grantham Lough Katie
Published: July 2010

Decreasing time and costs is a major objective in many businesses today. Including modularity in the early design phases can effectively decrease time spent on and costs associated with a project. The task of identifying modules within a product early in the design process (when decisions are less expensive) is made less daunting by using the techniques of functional modeling and module heuristics. This paper discusses the results of the initial efforts to verify the module heuristics on large products (products with functional models consisting of more than 30 sub-functions) since the module heuristics were originally developed on small products. Observations on needed modifications to the functional modeling technique and original module heuristics are reported along with an investigation of using potential risk statements to formulate modules. This work finds the original module heuristics do apply to large products with modifications and combining of heuristics.
Metamorphosis of Periodic Surface Models
Authors: Qi Cheng , Wang Yan
Published: July 2010

A phase transition is a geometric and topological transformation process of materials from one phase to another, each of which has a unique and homogeneous physical property. Providing an initial guess of transition path for further physical simulation studies is highly desirable in materials design. In this paper, we present a metamorphosis scheme for periodic surface (PS) models by interpolation in the PS parameter space. The proposed approach creates multiple potential transition paths for further selection based on three smoothness criteria. The goal is to search for a smooth transformation in phase transition analysis.
Design Improvement by Sensitivity Analysis (DISA) Under Interval Uncertainty Using Multi-Objective Optimization
Authors: Hamel J. , Li M. , Azarm S.
Published: July 2010

Uncertainty in the input parameters to an engineering system may not only degrade the system’s performance, but may also cause failure or infeasibility. This paper presents a new sensitivity analysis based approach called Design Improvement by Sensitivity Analysis (DISA). DISA analyzes the interval parameter uncertainty of a system and, using multi-objective optimization, determines an optimal combination of design improvements required to enhance performance and ensure feasibility. This is accomplished by providing a designer with options for both uncertainty reduction and, more importantly, slight design adjustments. The approach can provide improvements to a design of interest that will ensure a minimal amount of variation in the objective functions of the system while also ensuring the engineering feasibility of the system. A two stage sequential framework is used in order to effectively employ metamodeling techniques to approximate the analysis function of an engineering system and greatly increase the computational efficiency of the approach. This new approach has been applied to two engineering examples of varying difficulty to demonstrate its applicability and effectiveness.
Maximum Virtual Stiffness Distribution Analysis and Measurement for Haptic Device
Authors: Dai Xiaowei , Zhang Yuru , Wang Dangxiao
Published: July 2010

Maximum virtual stiffness is a critical performance measure for haptic devices. Stable haptic interaction is necessary for realistic feeling of virtual environment. The virtual environment is determined by the application and device. To ensure the stable haptic interaction, the virtual environment must be suitable for the device. Therefore, the virtual stiffness should not be greater than the minimum value of maximum virtual stiffness that a haptic device can stably render in the workspace. This paper proposes a method, utilizing the eigenvalue and eigenvector of stiffness matrix in joint space, to analyze and measure the maximum virtual stiffness distribution in the work space of a haptic device. Therefore, for a given haptic device, the maximum virtual stiffness at each position and orientation can be forecasted by this method. A new sufficient condition for haptic stability is also presented in the view of driven motor in this paper. A series experiments validate the effectiveness of this method.
Optimization Based Geometric Modeling of Nano/Micro Scale Ion Milling of Organic Materials
Authors: Fu Jing , Joshi Sanjay B.
Published: July 2010

Recently, Focused Ion Beam (FIB) instruments have begun be applied to organic materials such as polymers and biological systems. This provides a novel tool for sectioning biological samples for analysis, or microfabrication with environment friendly materials. The modeling of nano/micro scale geometry accurately sculptured by FIB milling is crucial for generating the milling plan and process control, and for computer simulation for prediction and visualization of the milled geometry. However, modeling of the ion milling process on compound materials, especially for high aspect ratio feature, is still difficult due to the complexity of target material, as well as multiple physical and chemical interactions involved. In this study, a comprehensive model of ion milling with organic targets is presented to address the challenges using a simulation based approach. This platform has also been validated by milling different features on water ice in a cryogenic environment, and the simulation and experiment results show great consistency. With the proliferation of nanotechnology to biomedical and biomaterial domains, the proposed approach is expected to be a flexible tool for various applications involving novel and heterogeneous milling targets.
An Efficient Method for Synthesizing Crank-Rocker Mechanisms for Generating Low Harmonic Curves
Authors: Wu Jun , Ge Q. J. , Gao Feng
Published: July 2010

This paper deals with the development of an efficient method for synthesizing crank-rocker mechanisms that are capable of generating perceptually simple and smooth paths that can be approximated by the first and second harmonics of Fourier series. Through the harmonic analysis of the loop closure equations of the crank-rocker mechanism, analytical relations among the nine design variables are identified. This reduces the dimensions of the search space to two and thereby greatly speed up the synthesis process.
A Virtual Reality Interface for the Design of Compliant Mechanisms
Authors: Seth Utkarsh , Su Hai-Jun , Vance Judy M.
Published: July 2010

The objective of this research is to develop an immersive interface and a design algorithm to facilitate the synthesis of compliant mechanisms from a user-centered design perspective. Compliant mechanisms are mechanical devices which produce motion or force through deflection or flexibility of their parts. Using the constraint-based method of design, the design process relies on the designer to identify the appropriate constraint sets to match the desired motion. Currently this approach requires considerable prior knowledge of how non-linear flexible members produce motion. As a result, the design process is based primarily on the designer’s previous experience and intuition. A user-centered methodology is suggested where the interface guides the designer throughout the design process, thus reducing the reliance on intuitive knowledge. This methodology supports constraint-based design methods by linking mathematical models to support compliant mechanism design in an immersive virtual environment. A virtual reality (VR) immersive interface enables the designer to input the intended motion path by simply grabbing and moving the object and letting the system decide which constraint spaces apply. The user-centered paradigm supports an approach that focuses on the designer defining the motion and the system generating the constraint sets, instead of the current method which relies heavily on the designer’s intuition to identify appropriate constraints. The result is an intelligent design framework that will allow a broader group of engineers to design complex compliant mechanisms, giving them new options to draw upon when searching for design solutions to critical problems.