bluuebunny/crossref_metadata_2025 huggingface dataset:
A Line Geometric Foundation for Finite Screw Systems Associated With Spatial Linkages
Authors: Huang Chintien , Hsing Tzu-Cheng
Published: June 2012

This paper investigates the line varieties corresponding to finite screw systems associated with spatial linkages. This research is based on the correspondence between a screw and a linear complex, and a screw system corresponds to the intersection of the linear complexes. In finite kinematics, two screw systems associated with the finite motions of the revolute-revolute (R-R) and prismatic-revolute (P-R) open chains have been discovered. These two screw systems also led to the discovery of the screw systems associated with the finite motions of the spatial 4R, spatial RPRP, and other overconstrained linkages. By using the intersection operation of linear complexes, this paper finds the linear reguli corresponding to the finite motions of R-R and P-R chains. Then we utilize the sum operation of the linear reguli corresponding to the R-R and P-R chains to obtain the hyperbolic linear congruences corresponding to the finite motions of the spatial 4R and RPRP linkages. The result presented here serves as a line geometric foundation for finite screw systems associated with spatial linkages. In addition, with CAD drawings, this paper enables the visualization of the obtained line varieties and their operations.
Automated Assignment of Physical Effects to Functions Using Ports Based on Bond Graphs
Authors: Helms Bergen , Schultheiß Hansjo¨rg , Shea Kristina
Published: June 2012

Innovation processes are highly susceptible to cyclic influences, such as evolving knowledge due to new technologies. In order to cope with these challenge, computational support is required. Paper-based design methods have vast amounts of knowledge at their disposal in the form of design catalogues. However, lacking a computational implementation, these knowledge sources provide no support for considering dynamic influences in the innovation process. The presented method is targeted at making the physical effects contained in design catalogues available for computational design synthesis approaches. For this purpose, this paper introduces the notion of abstraction ports that is used to represent the valid mapping between functional operators and physical effects. For the automated assignment of abstraction ports, a method has been developed that analyzes the equation structure of physical effects. This approach is derived from the modeling technique of bond graphs and is independent of any selection process proposed by design catalogues. Moreover, it allows for the formalization of evolving knowledge in new physical effects that are not yet contained in design catalogues. The assignment of abstraction ports has been successfully validated through the formalization of the physical effects of two design catalogues. Future work comprises the integration of quantitative characteristics of physical effects and the realization within the object-oriented graph grammar system booggie.
Energy Harvesting Characteristics of Conical Shells
Authors: Li H. , Hu S. D. , Tzou H. S.
Published: June 2012

Piezoelectric energy harvesting has experienced significant growth over the past few years. Various harvesting structures have been proposed to convert ambient vibration energies to electrical energy. However, these harvester’s base structures are mostly beams and some plates. Shells have great potential to harvest more energy. This study aims to evaluate a piezoelectric coupled conical shell based energy harvester system. Piezoelectric patches are laminated on the conical shell surface to convert vibration energy to electric energy. An open-circuit output voltage of the conical energy harvester is derived based on the thin-shell theory and the Donnel-Mushtari-Valsov theory. The open-circuit voltage and its derived energy consists of four components respectively resulting from the meridional and circular membrane strains, as well as the meridional and circular bending strains. Reducing the surface of the harvester to infinite small gives the spatial energy distribution on the shell surface. Then, the distributed modal energy harvesting characteristics of the proposed PVDF/conical shell harvester are evaluated in case studies. The results show that, for each mode with unit modal amplitude, the distribution depends on the mode shape, harvester location, and geometric parameters. The regions with high strain outputs yield higher modal energies. Accordingly, optimal locations for the PVDF harvester can be defined. Also, when modal amplitudes are specified, the overall energy of the conical shell harvester can be calculated.
A Comparison of Various Methods of Redundant Constraints Handling in Multibody System Simulations
Authors: Wojtyra Marek , Fra˛czek Janusz
Published: June 2012

When redundant constraints are present in a rigid body mechanism, only selected joint reactions can be determined uniquely, whereas the other cannot. Analytic criteria and numerical methods of finding joints with uniquely solvable reactions are available. In this paper the problem of joint reactions solvability is examined from the point of view of numerical methods frequently used for redundant constrains handling in practical simulations. Three methods are discussed: elimination of redundant constraints, pseudoinverse-based calculations and the augmented Lagrangian method. In each method the redundant constraints are treated differently which — in case of joints with non-unique reactions — leads to different reaction solutions. Moreover, it is shown that one and the same method may lead to different solutions, provided that input data are prepared differently. Finally, it is illustrated that — in case of joints with solvable reactions — the obtained solutions are unique, regardless of the method used for redundant constraints handling.
The Correction to Grubler Criterion for Calculating the Degrees of Freedoms of Mechanisms
Authors: Shai Offer
Published: June 2012

It is well known that the widely used Chybychev-Grubler Kutzbach’s criterion does not give the correct mobility for many mechanisms. In this paper we will show that if we add to the known Grubler equation the number of inner forces existing in the mechanism, termed self-stresses, we will derive the correct answer. The unique contribution of this paper is that it enables to find this correction on the given mechanism without any need to write the corresponding matrices or any equations. It should be noted that the correct mobility is obtained from the given configuration of the mechanism; that is the instantaneous mobility and not the global mobility.
Computational Schemes for Optimizing Domains of Attraction in Dynamical Systems
Authors: Castillo A´ngela , Zufiria Pedro J.
Published: June 2012

In this paper, several computational schemes are presented for the optimal tuning of the global behavior of nonlinear dynamical systems. Specifically, the maximization of the size of domains of attraction associated with invariants in parametrized dynamical systems is addressed. Cell Mapping (CM) techniques are used to estimate the size of the domains, and such size is then maximized via different optimization tools. First, a genetic algorithm is tested whose performance shows to be good for determining global maxima at the expense of high computational cost. Secondly, an iterative scheme based on a Stochastic Approximation procedure (the Kiefer-Wolfowitz algorithm) is evaluated showing acceptable performance at low cost. Finally, several schemes combining neural network based estimations and optimization procedures are addressed with promising results. The performance of the methods is illustrated with two applications: first on the well-known van der Pol equation with standard parametrization, and second the tuning of a controller for saturated systems.
Geometric Interpretation of Singular Configurations of a Class of Parallel Manipulators
Authors: Kong Xianwen , Yu Jingjun , Gosselin Cle´ment
Published: June 2012

This paper proposes an equivalent serial kinematic chain approach to identify the geometric characteristics of singular configurations of a class of parallel manipulators, which can be reduced to a structure composed of three XS and/or SX legs. Here, S and X denote respectively a spherical joint and a one-degree-of-freedom joint or generalized joint. The equivalent serial kinematic chain associated with a parallel kinematic chain composed of two XS legs is first obtained using the concept of reciprocal screws. The forward kinematic singularity (also static singularity) analysis of the parallel manipulators is then reduced to the singularity (stability) analysis of a single-loop structure. Finally, the geometric characteristics of singular configurations of the class of parallel manipulators are obtained with almost no algebraic derivation.
Hidden Markov Model for Health Estimation and Prognosis of Turbofan Engines
Authors: Giantomassi Andrea , Ferracuti Francesco , Benini Alessandro , Ippoliti Gianluca , Longhi Sauro , Petrucci Antonio
Published: June 2012

Determining the residual life time of systems is a determinant factor for machinery and environment safety. In this paper the problem of estimate the residual useful life (RUL) of turbo-fan engines is addressed. The adopted approach is especially suitable for situations in which a large amount of data is available offline, by allowing the processing of such data for the determination of RUL. The procedure allows to calculate the RUL through the following steps: features extraction by Artificial Neural Networks (ANN) and determination of remaining life time by-prediction models based on a Hidden Markov Model (HMM). Simulations confirm the effectiveness of the proposed approach and the promising power of Bayesian methods.
Stability Criteria of Flexible Details Milling
Authors: Voronov Sergey A. , Kiselev Igor A.
Published: June 2012

The vibrations inevitably occur while milling of the details with insufficient rigidity like the turbine blades for engines and various propulsion systems. This effect is undesirable as it decreases accuracy and the machined surface quality. The vibrations suppression is realized by applying additional damping or by choosing cutting conditions ensuring the process stability. In general the problem is solved by the determination of the process stability lobes. This criterion assumes that process is stable if the regenerative vibrations of tool or workpiece are damped. The additional criterion is discussed in the paper — the roughness of the machined surface. For this purpose authors elaborated the algorithm of the numerical simulation of milling process, considering the dynamics of tool and workpiece and applying the algorithm of machined surface geometrical modeling that takes into account the delay mechanism inherent to the process. The numerical solution of the simplified model in the given paper is considered. The Poincare’s maps of the vibration amplitudes, the machined surface errors, and the cutting force magnitudes depending on cutting conditions are presented. Authors conclude, that in general the vibration stability while milling process is not the absolute quality criterion. The combination of the developed criteria is introduced.
Design Preference Centered Review Recommendation: A Similarity Learning Approach
Authors: Jin Jian , Liu Ying , Ji Ping , Fung Richard
Published: June 2012

The rise of e-commerce websites like Amazon and Alibaba is changing the way how designers seek information to identify customer preferences in product design. From the feedbacks posted by consumers, either positive or negative, product designers can monitor the trend of consumers’ perception with respect to their product offerings and make efforts to improve accordingly. Starting from feature extraction from review documents, existing methods in identifying helpful online reviews regard the helpfulness prediction problem as a regression or classification problem and have not considered the relationship between customer reviews. Also, these approaches only consider the online helpfulness voting ratio or a unified helpfulness rating as the gold criteria for helpfulness evaluation and neglect various personal preferences from product designers. Therefore, in this paper, the focus is on how to predict reviews’ helpfulness by taking into account the personal preferences from both reviewers and designers. We start to analyze review helpfulness from both a generic aspect and a personal preference aspect. Classification methods and the proposed review similarity learning approach are utilized to estimate from the generic angle of helpfulness, while nearest neighbourhood based methods are adopted to reflect concerns from personal perspectives. Finally, a regression algorithm is called upon to predict review helpfulness based on the inputs from both aspects. Our experimental study, using a large quantity of review data crawled from Amazon and real ratings from product designers demonstrates the effectiveness of our approach and it opens a possibility for customized helpful review routing.
A Novel Control Strategy for Multiple Switches Based on Electro-Rheological Fluid
Authors: Xu Luning , Han Li , Liu Junbiao
Published: June 2012

A compact or portable mechatronic embedded system application has a strictly demands of volume and/or power consuming. Comparing with electronic parts, switches and/or actuators take the most proportion of volume or weight and power consuming of the whole system. A novel method of connecting multiple switches/actuators built by using electro-rheological fluid and a pair of governing electrodes and their control strategy are introduced in this paper. By using this method, the numbers of control components are changed from N times M to N plus M, the volume and weight reduced largely. A series structure is used in the application on multi-line Braille electro-book for blind people as a demonstration of this novel method. It provides a novel solution of shrinking system for a compact or portable mechatronic embedded system application.
Modeling, Analysis, and Experimental Validation of a Bifurcation-Based Microsensor
Authors: Kumar Vijay , Boley J. William , Yang Yushi , Ekowaluyo Hendrik , Miller Jacob K. , Chiu George T.-C. , Rhoads Jeffrey F.
Published: June 2012

Microelectromechanical chemical and biological sensors have garnered significant interest over the past two decades due to their ability to selectively detect very small amounts of added mass. Today, most resonant mass sensors utilize chemomechanically-induced shifts in the linear natural frequency for detection. In this paper, an alternative, amplitude-based sensing approach, which exploits dynamic transitions across saddle-node bifurcations that exist in a microresonator’s nonlinear frequency response, is investigated. In comparison to their more traditional, linear counterparts, these bifurcation-based sensors have the ability to provide improved sensor metrics, eliminate power-consuming hardware from final sensor implementations, and operate effectively at smaller (e.g. nano) scales. The present work details the ongoing development of a bifurcation-based mass sensor founded upon the near-resonant response of piezoelectrically-actuated microcantilevers. Specifically, the work details the modeling and analysis of these devices, their functionalization, and proof-of-concept mass sensing experiments which not only validate the proposed technique, but allow for the direct evaluation of pertinent sensor metrics.
Kinematic Synthesis for Infinitesimally and Multiply Separated Positions Using Geometric Constraint Programming
Authors: Schmiedeler James P. , Clark Barrett C. , Kinzel Edward C. , Pennock Gordon R.
Published: June 2012

Geometric Constraint Programming (GCP) is an approach to synthesizing planar mechanisms in the sketching mode of commercial parametric computer-aided design software by imposing geometric constraints using the software’s existing graphical user interface. GCP complements the accuracy of analytical methods with the intuition developed from graphical methods. Its applicability to motion generation, function generation, and path generation for finitely separated positions has been previously reported. This paper demonstrates how GCP can be applied to kinematic synthesis for motion generation involving infinitesimally and multiply separated positions. For these cases, the graphically imposed geometric constraints alone will in general not provide a solution, so the designer must parametrically relate dimensions of entities within the graphical construction to achieve designs that automatically update when a defining parameter is altered. For three infinitesimally separated positions, the designer constructs an acceleration polygon to locate the inflection circle defined by the desired motion state. With the inflection circle in place, the designer can rapidly explore the design space using the graphical second Bobillier construction. For multiply separated position problems in which only two infinitesimally separated positions are considered, the designer constrains the instant center of the mechanism to be in the desired location. Example four-bar linkages are designed using these techniques with three infinitesimally separated positions and two different combinations of four multiply separated positions.
Vision Based Autonomous Tracked Sorting Robot
Authors: Al Nabulsi A. , Zein Alabedin A. , Fayyad J. , Ismail M. , Jarrah M.
Published: June 2012

This paper presents the learning experience gained while designing and implementing a vision based autonomous tracked sorting robot in a mechatronics design class for its application in color based sorting, mapping and exploration missions. The different steps taken in order to reach the final system are presented. This paper focuses on the kinematic modeling of the tracked vehicle and the gripper, and discusses in details the selection process of the reboot’s components. The system was tested and results are shown using snap shots of the final demo.
Complex Modal Analysis of the Swimming Motion of a Whiting
Authors: Feeny B. F. , Feeny A. K.
Published: June 2012

The kinematics of the transverse motion of a swimming fish are analyzed using a complex modal decomposition. Cinematographic images of a swimming whiting (Gadus merlangus) were obtained from the work of Sir James Gray (Journal of Experimental Biology, 1933). The position of the midline for each image was determined, and used to produce planar positions of virtual markers distributed along the midline of the fish. Transverse deflections of each virtual marker were used for the complex orthogonal decomposition of modes. This method was applied to a normal whiting and an amputated whiting, both of Gray’s paper. The fish motions were well represented by a single complex mode, which was used as a modal filter. The modal coordinate was also extracted. The mode and modal coordinate were used to estimate the frequency, wavelength, and wave speed. The amputated fish was compared to the non-amputated fish, and the different amount of traveling in the respective waveforms was quantified.
The Use of Time-Frequency Methods in Rotor/Stator Impact-Rubbing Detection
Authors: Liska Jindrich , Jakl Jan , Cerny Vaclav
Published: June 2012

At present, detailed rubbing diagnostics is implemented as off-line analysis of measured data. During the machine operation, the overall level of vibration and the rotational frequency (1X) phasor are traced. On the basis of amplitude and phase changes, the presence of rub is identified. Although unmonitored, changes in sub synchronous spectral components are also caused by rubbing. The new method presented herein utilizes measurements of these changes for better online rubbing detection. The paper presents the authors work on rotor/stator rub detection in steam turbines. For automatic rubbing detection, an on-line tool, called cumulative full-spectra method and based on full-spectra computation, is proposed. The proposed automatic detection algorithm is based on characteristic value, which is computed using special norming of tracked frequencies in the cumulative full-spectra.
Multibody Modelling of Spalled Rolling Bearings: Effectiveness of Different Contact Algorithms
Authors: Malago´ Marco , Moens David , Jacobs William , Sas Paul
Published: June 2012

This study analyses a dynamic multibody model of a deep groove single row ball bearing. The objective of the study is to simulate the dynamic behavior of a bearing under different operational conditions. Typical vibration signals used in bearing diagnostics are simulated using the non-linear Hertzian contact theory. Geometry, material properties, friction and damping coefficients are considered as input while displacements, velocities, accelerations and forces between bearing rings are calculated and validated with the analytical formulations found in literature. Furthermore localized faults are introduced in the simulation in order to extract bearing defect frequencies and to represent the real vibration signal signature in case of fault components. For this purpose, a simplified model is realized using the polygonal contact model. This approach allows to investigate more in detail the effect of localized defects by reproducing the real rolling elements trajectories through a discretization of the contact surfaces. The low computation efficiency compared to the traditional Hertzian approach limits the application of this contact algorithm on the complete bearing model. Nevertheless, the simplified model allows to draw conclusions regarding the influence of the shaft/cage speed on the fault size estimation giving an innovative contribution on bearing diagnostics.
Effects of Strain Rate on the Stress Propagations in Bonded Shrink Fitted Joints Under Impact Push-Off Loadings
Authors: Liao Lijuan , Sawa Toshiyuki , Kobayashi Takashi , Goda Yasuhiro
Published: June 2012

The effects of the strain rate sensitivity on the stress propagations of bonded shrink fitted joint, in which a ring is fitted using an adhesive layer at the middle part of a shaft, subjected to impact push-off loadings are examined. The plastic flow deformation behaviors of structural adhesive under some strain rates are examined experimentally. In addition, the stress wave propagations in the joint are analyzed using finite element method (FEM). The experimental results show that the yield stress of the adhesive increases as the strain rate increases nonlinearly. It is observed that the maximum equivalent von Mises stress occurs in the adhesive layer at the upper interfaces, which causes the rupture of the joint based on the numerical calculations. Furthermore, the strain responses obtained from numerical and experimental methods are compared with each other. A fairly good agreement is obtained between FEM calculations and experiments. In addition, the joint strength is predicted by impact energy using experimental results, which is about 20.85 J in the present study.
uBlasCL: Architecture Agnostic Massively Parallel Linear Algebra System
Authors: Iliopoulos Athanasios , Michopoulos John G.
Published: June 2012

The need for more efficient, more abstract and easier to use parallel programming interfaces has been recently intensified with the introduction and remarkable evolution of technologies such as the General Purpose Graphics Processing Units (GPG-PUs) and multi-core Central Processing Units (CPUs). In the present paper we present the introduction of the uBlasCL system as a Domain Specific Embedded Language within C++ that implements a Basic Linear Algebra Interface for OpenCL. The system is architecture agnostic, in the sense that it can be programmed independently of the targeted architecture, is massively parallel, and achieves efficiency that tracks well the increase in hardware performance advances. Our effort is based on the utilization of template metaprogramming and domain specific languages fundamentals, for developing a system that has the syntactic flexibility of a symbolic term processing system for expressing mathematics, and the semantic and executional power to exploit the parallelism offered by the hardware in an automated, transparent to the user, and efficiently mapped on the hardware manner. We also describe its relation to C++, template programming, domain specific languages and OpenCL. In the effort to develop uBlasCL we also developed a middleware library named CL++, as a convenient C++ interface to OpenCL. After the architectural and the implementation descriptions of the system, we present performance testing results demonstrating its potential power.
Further Remarks on Invariance Properties of Time-Delay Systems
Authors: Stankovic´ Nikola , Olaru Sorin , Niculescu Silviu-Iulian
Published: June 2012

For various problems of practical importance, such as disturbance rejection or constrained control, the determination of invariant sets provides insightful information on the influence of unknown bounded signals on the dynamical system behavior. In order to characterize the effect of those signals on the system, the determination of the minimal robust positively invariant (mRPI) set is of great interest. On the other side, the presence of time delays is ubiquitous in process control and it seems natural to use invariant set theory to analyze time delay systems affected by additive disturbance. The present paper deals with computation and characterization of the delay-independent minimal robust positively invariant region in the set-theoretic framework. The Banach fixed point theorem will be used to specify the existence and uniqueness conditions for this set. Here we also provide a procedure for the construction of invariant approximations of this limit set as well as discussion on the efficient computation for practical usage. Supplementary, at the end is pointed out an interesting correlation between proposed results and existence of the mRPI sets for switching dynamics. In this study we are particularly interested in discrete time systems. Outlined results are confirmed by a numerical example.
Synthesis of Actuation Spaces of Multi-Axis Parallel Flexure Mechanisms Based on Screw Theory
Authors: Qiu C. , Yu J. J. , Li S. Z. , Su Hai-jun , Zeng Y. Z.
Published: June 2012

This paper introduces an approach for synthesis of actuation spaces of multi-axis parallel flexure mechanisms. The concept of actuation space, first proposed by J. Hopkins and M. Culpepper, is developed from constraint and freedom space, which are two fundamental concepts in constraint-based method. Within the framework of screw theory, actuation and constraint can be represented mathematically by a wrench, and freedom can be depicted by a twist. A Compliance matrix is provided to set the relationship between constraint wrenches and actuation forces in view that such an important rule as “actuation forces are linear independent of constraint wrenches”. Developed from this design rule, a synthesis criterion of actuation space of flexure systems is promoted to select suitable actuators. As a result, this synthesis criterion enable designers to (i) formulate the actuation space systematically in the format of screws or screw system, (ii) determine actuator placement according to the requirement of minimizing the interference between actuation forces and constraint wrenches. Synthesis procedures and selective examples are discussed in details.
Experiential Learning Based Engineering Curriculum to Develop Meta-Competencies
Authors: Siddique Zahed , Bradshaw Amy , Hardre´ Patricia , Mistree Farrokh
Published: June 2012

The competitiveness of the U.S., which is linked to our standard of living, is dependent on our ability to produce a large number of sufficiently innovative engineers prepared to address issues related to complex systems. Hence, our focus is on research and the associated development of curriculum and instructional activities that address the engineering competencies related to innovation. In this paper, we present a hierarchical curriculum design model, grounded in experiential learning. The model addresses curriculum design from multiple levels: design of experiential activities to provide targeted scaffolding and support for engineering students to develop competencies, then mapping the competencies at course, course sequence, and curriculum levels, for systemic development of competencies at higher order cognition. We illustrate the hierarchical approach for the design of a three-course sequence around the Formula Society of Automotive Engineers (FSAE) Racing team at University of Oklahoma, Norman, to foster meaningful learning, innovation, systems-level thinking, and the attainment of career-sustaining skills through authentic experiences. With a view to stimulating discussion, in this paper we highlight some of the salient features of our plan and some issues that warrant further investigation.
Development of a Test Rig for Multi-Axial Static and Dynamic Loading of Bearings
Authors: Jacobs William , Malago´ Marco , Boonen Rene , Sas Paul , Moens David
Published: June 2012

Condition monitoring of bearings has been a major research topic for more than five decades. To validate and improve the condition monitoring techniques, this paper focuses on the development of an innovative and versatile bearing test rig. The rig allows applying a fully controlled multi-axial static and dynamic load on different types and sizes of bearings. Easy adjustment to mount bearings with different inner diameter, outer diameter and width is possible, without compromising on performance. Furthermore, the behaviour of the bearing is monitored by accelerometers, proximity probes and thermocouples. During the design of the rig, several techniques were applied to ensure clean measurements, with maximum repeatability, and to reduce errors due to temperature variations. Finally, introducing an additional dynamic force on the bearing makes it possible to load the bearing as if it were built into a real machine, for example a gearbox. At the time this paper is written, results of the test rig were not yet available. However, the authors expect to be able to report on the first test results during the conference.
Mobility and Singularity Analysis of a Class of 2-DOF Rotational Parallel Mechanisms Using a Visual Graphic Approach
Authors: Yu J. J. , Dong X. , Pei X. , Zong G. H. , Kong Xianwen , Qiu Qunxian
Published: June 2012

In this paper, a simple and straightforward visual graphic approach for mobility and singularity analysis of mechanisms is introduced. Although the proposed method is established upon the reciprocal screw system theory, it needs no formula derivation instead knowing about a few simple rules. As a study case, mobility and singularity analysis for a class of two degrees-of-freedom (DOF) rotational parallel mechanisms i.e. well-know Omni-Wrist III with four limbs, and its two derived architectures with three limbs (named T-type and δ-type) is analyzed by the proposed method. As a result, a novel PKM derived from Omni-Wrist III is presented, which has the DOF and kinematics property close to Omni Wrist III.
End of Life Decision Making for Used Products With Uncertain Quantity of Return
Authors: Behdad Sara , Williams Aida Sefic , Thurston Deborah
Published: June 2012

The management of end-of-life electronic waste (e-waste) attracts significant attention due to environmental concerns, legislative requirements, consumer interests in green products and market image of manufacturers. However, managing e-waste is complicated by some factors including the high degree of uncertainty of quantity, timing of arrival and quality of the returned products. The variability in the stream of returned end of life (EOL) products makes it difficult to plan for facility materials, equipment and human resource requirements. The aim of this research is to tackle the uncertainty associated with the quantity of received used products. A stochastic programming model for waste stream acquisition systems (compare to market driven systems) is introduced. The model considers the quantity of returned product as an uncertain parameter and determines to what extend the product should be disassembled and what is the best end of life option for each subassembly. The stochastic model is defined in a form of chance constrained programming and is then converted to a mixed integer linear programming. An example is provided to show the application of the model for an uncertain stream of CPUs received in a refurbishing company. Remanufacturers must then decide which proportion of disassembled modules should be processed given specific remanufacturing options.
Detecting Risk of Intellectual Property (IP) Leakage due to Reverse Design in Collaborative Product Development Environments
Authors: Cao Xinlin , Zeng Yong
Published: June 2012

Intellectual Property (IP) leakage during collaborative product development is drawing more and more attentions nowadays. Unlike most of existing research, which is focused on the effect of IP leakage on the supply chain’s material and information flows, we propose a reverse design based conceptual model of information leakage during collaborative product development environments. In addition, a generic extensible framework is proposed to detect and estimate the IP leakage due to reverse design. Specifically, we propose an inference model to obtain inferred knowledge based on public knowledge and shared knowledge. We also present an algorithm to detect potential IP leakage due to reverse design in collaborative product development environments when potential competition may exist between a product partner and the manufacturer. An industrial example is used to demonstrate the problem and our proposed approach.
A New Variable Stiffness Suspension Mechanism
Authors: Anubi Olugbenga M. , Crane Carl D.
Published: June 2012

A new variable stiffness suspension system based on a recent variable stiffness mechanism is proposed. The overall system is composed of the traditional passive suspension system augmented with a variable stiffness mechanism. The main idea is to improve suspension performance by varying stiffness in response to road disturbance. The system is analyzed using a quarter car model. The passive case shows much better performance in ride comfort over the tradition counterpart. Analysis of the invariant equation shows that the car body acceleration transfer function magnitude can be reduced at both the tire-hop and rattle space frequencies using the lever displacement transfer function thereby resulting in a better performance over the traditional passive suspension system. An H∞ controller is designed to correct for the performance degradation in the rattle space thereby providing the best trade-off between the ride comfort, suspension deflection and road holding.
Determination of Minimum Time Rendezvous Points for Multiple Mobile Robots via Level Set Methods
Authors: Brown Travis L. , Aslam Tariq D. , Schmiedeler James P.
Published: June 2012

This paper addresses the problem of finding the minimum time rendezvous point for a geographically distributed group of heterogeneous mobile robots. In contrast to the traditional treatment of the multi-agent rendezvous problem, focus is given mainly to the identification of the globally optimal solution rather than the behavior of the system based on a given control policy. Level sets are introduced as a tool to solve this problem by first computing an arrival time map for each robot, subject to speed, terrain, and dynamic constraints. The computation is parallelizable by requiring each agent to generate its own arrival time map. The arrival time maps can be easily combined to give the overall minimum time rendezvous point. Despite the apparent simplicity of this approach, it is capable of accommodating numerous complicating factors with minimal modification while simultaneously generating a target path trajectory for each robot through the state-space. Examples involving ground, sea, and air robots are used to illustrate the power of this technique.
A Novel 3D Interaction Technique Based on the Eye Tracking for Mixed Reality Environments
Authors: Caruso Giandomenico , Bordegoni Monica
Published: June 2012

The paper describes a novel 3D interaction technique based on Eye Tracking (ET) for Mixed Reality (MR) environments. We have developed a system that integrates a commercial ET technology with a MR display technology. The system elaborates the data coming from the ET in order to obtain the 3D position of the user’s gaze. A specific calibration procedure has been developed for correctly computing the gaze position according to the user. The accuracy and the precision of the system have been assessed by performing several tests with a group of users. Besides, we have compared the 3D gaze position in real, virtual and mixed environments in order to check if there are differences when the user sees real or virtual objects. The paper also proposes an application example by means of which we have assessed the global usability of the system.
An Experimental Investigation of the Effect of Tooth Asymmetry and Tooth Root Shape on Root Stresses and Single Tooth Bending Fatigue Life of Gear Teeth
Authors: Sanders Aaron , Houser Donald R. , Kahraman Ahmet , Harianto Jonny , Shon Sam
Published: June 2012

In this paper, effects of root fillet geometry and tooth asymmetry on tooth bending stresses and fatigue lives of spur gears are investigated. For this purpose, an existing gear analysis model, the Load Distribution Program (LDP), is employed to define four basic tooth geometry variations. These four variations are (i) symmetric tooth profiles (i.e. identical loaded and unloaded flanks) with full circular root geometry (at the maximum radius possible), (ii) symmetric tooth profiles with an elliptical root geometry, (iii) asymmetric tooth profiles (i.e. loaded and unloaded flanks at different pressure angles) with full circular root geometries, and (iv) asymmetric tooth profiles with an elliptical root geometry on the right (loaded) flank and a circular root geometry on the left flank. Under these conditions, variations (ii), (iii), and (iv) are predicted to have maximum root stresses that are 7.6%, 22.4%, and 24.3% less than that of the baseline case (i). Actual test articles representing these four variations were qualified through dimensional measurements of the profiles and the root fillet regions. The roots of several of the teeth of each gear type were instrumented and strain measurements under various tooth load levels are compared with the predictions. Single tooth bending fatigue tests were also performed to obtain fatigue data for each variation of the test gears. The resultant tooth bending fatigue performance of each gear variation is shown to correlate with the level of root stress reduction achieved. Experiments indicate that the most significant life increases compared to the baseline conditions are achieved with the last variation (asymmetric tooth profiles and an elliptical root shape), where the mean life is increased by more than 30 times. It is also shown through examination of the broken teeth that the critical locations where the cracks initiated agree well with the predicted locations of the maximum root stresses.
Using Wikis as a Formative Assessment Tool for Student Engineering Design Teams
Authors: Moore Jacob P. , Williams Christopher B. , Paretti Marie C.
Published: June 2012

Due to its focus in project-based learning, design educators must provide individual coaching and mentoring of student teams as they progress through their design efforts. In order to increase the quantity and quality of design mentoring, the authors have implemented the use of Wiki websites as a medium for providing formative assessment for student design teams enrolled in a sophomore-level Mechanical Engineering design course. Wiki websites, which allow for easy creation and editing of interlinked webpages, were created for each design team in order to provide a virtual space for the creation, compilation, and editing of their design project report submissions. With access to each team’s Wiki site, the mentor is able to observe each team’s product design process unfold and provide feedback using an embedded commenting system. The public presentation of design reports also affords the facilitation of a peer-review of student work. In this paper the authors present details of the implementation of a Wiki for preliminary assessment data for this tool. Results show that the students found the tool and the associated activities to be easy to use, helpful in developing better design reports and a contributing factor to their development of critical and analytical thinking skills. In addition, students who used the tool reported receiving more meaningful formative feedback from the instructor and reported giving more formative feedback to their peers when compared to other sections of the class that were not using the Wiki.
Design Preference Elicitation Using Efficient Global Optimization
Authors: Ren Yi , Papalambros Panos Y.
Published: June 2012

We seek to elicit individual design preferences through user-computer interaction. During an iteration of the interactive session, the computer presents a set of designs to the user who then picks any preferred designs from the set. The computer learns from this feedback and creates the next set of designs using its accumulated knowledge to minimize a merit function. Under the hypothesis that user responses are deterministic, we show that an effective query scheme is akin to the Efficient Global Optimization (EGO) algorithm. Using simulated interactions, we discuss how the merit function form and user preference sensitivity can affect search efficiency and hence the time to complete an interactive session. We demonstrate the proposed algorithm in the design of vehicle exteriors.
Dynamic Modelling of a Traveling-Wave Type Ultrasonic Motor With Beam Teeth via Finite Elements
Authors: Chao Paul C.-P. , Lu Po-Hung , Chiu Chun-Wei
Published: June 2012

The study is dedicated to establish the dynamic model of a traveling-wave type ultrasonic motor (USM) with beam teeth via finite elements. The modeling is accomplished mainly by finite elements, the task of which consists of three parts — for stator, rotor and contact. It is first assumed that the complex dynamics of the stator emulates a single one-dimensional Euler-beam vibrating harmonically in the transverse direction. On the top surfaces of the stator are vertical beam teeth that is in contact with rotor, which is simply a thin disk fixed to spindle. The friction between the teeth tips and stator rotates the spindle moves the stator and finally rotates the disk to the desired speed. A contact model between beam tips and rotor disk with proper friction assumed is next built in conjunction with the established finite element model of the rotor disk. With a complete model in hands, the dynamics of the USM is predicted along with associated exerted torques. Experiments are finally conducted for collecting sets of data of rotation speeds versus torques that validate the effectiveness of the built models for the motor, stator and contact force.
LIVE: A Work-Centered Approach to Support Visual Analytics of Multi-Dimensional Engineering Design Data With Interactive Visualization and Data-Mining
Authors: Yan Xin , Qiao Mu , Simpson Timothy W. , Li Jia , Zhang Xiaolong Luke
Published: June 2012

During the process of trade space exploration, information overload has become a notable problem. To find the best design, designers need more efficient tools to analyze the data, explore possible hidden patterns, and identify preferable solutions. When dealing with large-scale, multi-dimensional, continuous data sets (e.g., design alternatives and potential solutions), designers can be easily overwhelmed by the volume and complexity of the data. Traditional information visualization tools have some limits to support the analysis and knowledge exploration of such data, largely because they usually emphasize the visual presentation of and user interaction with data sets, and lack the capacity to identify hidden data patterns that are critical to in-depth analysis. There is a need for the integration of user-centered visualization designs and data-oriented data analysis algorithms in support of complex data analysis. In this paper, we present a work-centered approach to support visual analytics of multi-dimensional engineering design data by combining visualization, user interaction, and computational algorithms. We describe a system, Learning-based Interactive Visualization for Engineering design (LIVE), that allows designer to interactively examine large design input data and performance output data analysis simultaneously through visualization. We expect that our approach can help designers analyze complex design data more efficiently and effectively. We report our preliminary evaluation on the use of our system in analyzing a design problem related to aircraft wing sizing.
A Knowledge Discovery in Databases (KDD) Approach for Extracting Causes of Iterations in Engineering Change Orders
Authors: Elezi Fatos , Sharafi Armin , Mirson Alexander , Wolf Petra , Krcmar Helmut , Lindemann Udo
Published: June 2012

This paper describes an implementation of a Knowledge Discovery in Databases (KDD) process for extracting the causes of iterations in Engineering Change Orders (ECOs). A data set of approximately 53,000 historical Engineering Change Orders (ECOs) was used for this purpose. Initially, the impact of iterations in ECO lead time and uncertainty is assessed. Subsequently, a semi-automatic text-mining process is employed to classify the causes of iterations. As a result, cost and technical categories of causes were identified as the main reasons for the occurrence of iterations. The study concludes that applying KDD in historic ECO data can help in identifying the causes of iterations of ECO which subsequently can provide a framework for companies to reduce these iterations. In addition, the case represents an example of benefits that can be achieved with the application of KDD in engineering change management.
Customer-Driven Product Design Selection Using Web Based User-Generated Content
Authors: Wang L. , Youn B. D. , Azarm S. , Kannan P. K.
Published: June 2012

Acquisition of the customer data for product design selection using conventional customer survey techniques can be a time-consuming and costly undertaking. The aim of this paper is to overcome this limitation by using web based User-Generated Content (UGC) as an alternative to the conventional customer survey techniques. UGC refers to various public media contents created by web users including contents in online customer reviews, blogs, and social networking interactions. So far, there has not been any systematic effort in using UGC in design selection for a customer durable product. Using UGC in product design selection is not an easy task because UGC can be freely expressed and written by customers with little constraints, structure and bounds. As a result, UGC can contain a lot of noise, variability in content and even bias induced by the customers. In order to make use of UGC, this paper develops a systematic methodology for eliciting product attributes from UGC, constructing customer preference models and using these models in design selection. To demonstrate the proposed method, design selection of a smartphone using UGC is considered as an example. It is shown in the example that the proposed method can provide a reasonable estimation of customer preferences while being useful for product design selection.