bluuebunny/crossref_metadata_2025 huggingface dataset:
Wireless Sensing of Physical Parameters Inside Hermetically Enclosed Conductive Envelopes
Authors: Kluge Martin , Sabater Jordi , Schalk Josef , Ngo Luong V. , Seidel Helmut , Schmid Ulrich
Published: May 2009

In the modern aeronautics and aerospace industry, there is a manifold amount of applications emerging for wireless sensors. While many new systems are making use of radio transmitters, EADS Innovation Works has developed a concept for transmitting energy and data to the inside of hermetically sealed envelopes used for hydraulic accumulators, fuel tanks, oxygen bottles, etc. For such kind of metal enclosures, the use of radio frequency is impossible as the electromagnetic waves are blocked by the surrounding material. Classical approaches like using wire-based feed-throughs threaten the reliability of the overall system and hence, they are less attractive especially when safety relevant components are targeted. The system described in this paper makes use of ultrasonic transmission techniques in order to power and communicate with a wireless sensor inside a metal enclosure. An innovative platform and communication concept allows to efficiently read data from basically any type of low power commercial sensors of the shelf. Major design drivers for the overall system are a high level of integration and high reliability.
Computation of the Maximal Singularity-Free Workspace of the MSSM for a Given Orientation
Authors: Jiang Qimi , Gosselin Cle´ment M.
Published: May 2009

The maximal singularity-free workspace of parallel mechanisms is a desirable criterion in robot design. However, for a 6-dof parallel mechanism, it is very difficult to find an analytic method to determine the maximal singularity-free workspace around a prescribed point for a given orientation. Hence, a numerical algorithm is presented in this paper to compute the maximal singularity-free workspace as well as the corresponding leg length ranges of the MSSM Gough-Stewart platform. This algorithm is based on the relationship between the maximal singularity-free workspace and the singularity surface. Case studies with different orientations are performed to demonstrate the presented algorithm. The results obtained can be applied to the geometric design or parameter (leg length) setup of the MSSM parallel robots.
Evolutionary Computing Applied to Design Optimization
Authors: Marzouk Osama A.
Published: May 2009

Inspired by Darwin’s theory of evolution, the genetic algorithm (GA) method is part of evolutionary computing. It is a search technique used to find solutions and optimize them. This method has found application in different fields, such as computer science, engineering, chemistry, economics, physics, and mathematics. In the present study, GA is used to optimize airfoil geometry for high lift in the low-speed subsonic regime. The variable to be optimized is the set of coordinates of several points along the airfoil surface, which constructs its geometry. We seek a geometrical design that maximizes the fitness function (also called objective function), which is chosen to be the lift coefficient. The process is done in successive cycles, until a satisfactory design is achieved. At the end of each cycle, a group (or a generation) of candidate designs, is generated using stochastic searching. The method involves binary encoding-decoding and mutating as well. An aerodynamic flow solver is augmented in the GA procedure; it evaluates the fitness function at each cycle. A special procedure in evaluating the fitness function is used so that impractical geometrical designs are eliminated automatically.
Reduction of Non-Monomial Basis in the Dimensional Analysis of a Dynamical System
Authors: Tadepalli Srikanth , Wood Kristin L.
Published: May 2009

Dimensional Analysis (DA) is a tool often used to relate models and specimens to the actual product or system based on the hypothesis that the two regimes follow the same physical laws and are hence dimensionally equivalent. While this has been a conventional use of the process, we extend the technique to dynamic systems to develop state equations that allow for design studies and optimization. A methodical approach is detailed coupled with an example of a toy water-rocket assembly. A modified methodology (heuristic) is also discussed to condense non-monomial basis systems using simple physical laws and a novel reduction process. Experimental verification is provided to complement the analysis procedure. Efficacy of the process is highlighted in comparison with the conventional close-form approach.
Kinematic Representations of Pop-Up Paper Mechanisms
Authors: Winder Brian G. , Magleby Spencer P. , Howell Larry L.
Published: May 2009

Pop-up paper mechanisms use techniques very similar to the well-studied paper folding techniques of origami. However, popups differ in both the manner of construction and the target uses, warranting further study. This paper outlines the use of planar and spherical kinematics to model commonly used pop-up paper mechanisms. A survey of common joint types is given, including folds, interlocking slots, bends, pivots, sliders and rotating sliders. Also included is an overview of common onepiece and layered mechanisms, including single-slit, double-slit, V-fold, tent, tube strap and arch mechanisms. Each mechanism or joint is described using a kinematic or compliant mechanism representation. In addition, it is shown that more complex mechanisms may be created by combining simple mechanisms in various ways. The principles presented are applied to the creation of new pop-up joints and mechanisms. The new mechanisms employ both spherical and spatial kinematic chains. Various other applications are also mentioned which could benefit from the use of pop-up mechanism principles. Possible applications include deployable structures, packaging and instruments for minimally invasive surgery.
Multi Agent Normal Sampling Technique (MANST) for Global Optimization
Authors: Saremi Alireza , Al-Hinai Nasr , Wang G. Gary , ElMekkawy Tarek
Published: May 2009

The current work discusses a novel global optimization method called the Multi-Agent Normal Sampling Technique (MANST). MANST is based on systematic sampling of points around agents; each agent in MANST represents a candidate solution of the problem. All agents compete with each other for a larger share of available resources. The performance of all agents is periodically evaluated and a specific number of agents who show no promising achievements are deleted; new agents are generated in the proximity of those promising agents. This process continues until the agents converge to the global optimum. MANST is a standalone global optimization technique. It is benchmarked with six well-known test cases and the results are then compared with those obtained from Matlab™ 7.1 GA Toolbox. The test results showed that MANST outperformed Matlab™ 7.1 GA Toolbox for the benchmark problems in terms of accuracy, number of function evaluations, and CPU time.
Path Tracking Design Based on Jerk Input Fractional Prefilter and Jerk Limited Input Shaper Approaches
Authors: Melchior Pierre , Jallouli-Khlif Rim , Orsoni Bruno , Derbel Nabil , Oustaloup Alain
Published: May 2009

In path tracking design, different methods were developed. In previous works we have presented a method based on fractional differentiation in order to reduce overshoots on the actuator output. It allows the generation of an optimal movement reference-input leading to a minimum path completion time, taking into account the maximum velocity, acceleration and jerk, and the bandwidth of the closed-loop on which the input is applied. Different strategies were developed. In this paper, three methods taking into account the jerk limitation are compared. A comparison with classical input shaper approach is also done. The two first methods, based on fractional differentiation, are used through a Davidson-Cole prefilter with acceleration or jerk bang bang input, to ensure continuity on acceleration and jerk signals on the actuator. The third approach is based on preshaper synthesis with jerk limited input; the shaped input is obtained by convolving desired input with an impulse sequence. The synthesis methodologies of the different methods are studied. Performances are compared on an example, in both frequency and time domains.
Incorporating Customer Preferences and Market Trends in Vehicle Package Design
Authors: Kumar Deepak , Hoyle Chris , Chen Wei , Wang Nanxin , Gomez-Levi Gianna , Koppelman Frank S.
Published: May 2009

Demand models play a critical role in enterprise-driven design by expressing revenues and costs as functions of product attributes. However, existing demand modeling approaches in the design literature do not sufficiently address the unique issues that arise when complex systems are being considered. Current approaches typically consider customer preferences for only quantitative product characteristics and do not offer a methodology to incorporate customer preference-data from multiple component/subsystem-specific surveys to make product-level design trade-offs. In this paper, we propose a hierarchical choice modeling approach that addresses the special needs of complex engineering systems. The approach incorporates the use of qualitative attributes and provides a framework for pooling data from multiple sources. Heterogeneity in the market and in customer-preferences is explicitly considered in the choice model to accurately reflect choice behavior. Ordered logistic regression is introduced to model survey-ratings and is shown to be free of the deficiencies associated with competing techniques, and a Nested Logit-based approach is proposed to estimate a system-level demand model by pooling data from multiple component/subsystem-specific surveys. The design of the automotive vehicle occupant package is used to demonstrate the proposed approach and the impact of both packaging design decisions and customer demographics upon vehicle choice are investigated. The focus of this paper is on demonstrating the demand (choice) modeling aspects of the approach rather than on the vehicle package design.
Metamodeling of Mechatronic Systems in the MIXEDMODELS Platform
Authors: Vaze Shilpa A. , Krishnaswami Prakash , DeVault James
Published: May 2009

The parametric design of mechatronic systems requires several detailed analyses of the system, thereby slowing down the design process significantly. In the recent past, there has been a lot of interest in using lower fidelity, but higher efficiency metamodels (also called surrogate models) instead of the actual detailed models to guide parametric design, particularly in the early stages of parametric design. One common approach to forming metamodels is to run the detailed model to obtain the system response at selected points in design space and fit a response surface to the results which becomes the metamodel. Since this method uses only zero order information at each design point, a large number of points are required to form a reasonably accurate metamodel. For example, in a single design variable problem, a two-point response surface can only be linear, whereas we can generate a cubic response surface if we also had derivative information at the two points. In this paper, we present a metamodeling approach for mechatronic systems that computes and utilizes first order derivative information at each point in the design space at which a detailed analysis is performed. The first order derivative information that is computed is the set of design sensitivity coefficients of the system state variables and performance functions. A unified modeling approach for the mechanical, electrical, and electronic aspects of the system is first developed. This approach generates a single set of governing equations for the entire system in the form of a system of differential-algebraic equations (DAE’s). Based on these DAE’s, a set of equations in the state design sensitivity coefficients is analytically derived using a direct differentiation approach. This set of equations also turns out to be a set of DAE’s which can be solved simultaneously in parallel with the system governing equations. We have successfully implemented this methodology for design sensitivity analysis of multidisciplinary systems in a computational platform called MIXEDMODELS (Multidisciplinary Integrated eXtensible Engine for Driving Metamodeling, Optimization, and DEsign of Large-scale Systems). Once we know the state design sensitivity coefficients, we can compute the design sensitivity coefficients of any system performance function. After we have obtained the necessary design sensitivity information, we can devise several schemes for generating a metamodel for the system based on the sensitivity information. Some examples of metamodels obtained using this approach are presented for selected mechatronic systems, along with the relevant accuracy measures.
A Hierarchical Statistical Sensitivity Analysis Method for Complex Engineering Systems
Authors: Yin Xiaolei , Chen Wei
Published: May 2009

The method of Statistical Sensitivity Analysis (SSA) is playing an increasingly important role in engineering design, especially with the consideration of uncertainty. However, applying SSA to the design of complex engineering systems is not straight forward due to both computational and organizational difficulties. In this paper, a Hierarchical Statistical Sensitivity Analysis (HSSA) method is developed to facilitate the application of SSA to the design of complex systems especially those follow hierarchical modeling structures. A top-down strategy for HSSA is introduced to only invoke the SSA of critical submodels based on the significance of submodel performances. A simplified formulation of the Global Statistical Sensitivity Index (GSSI) is studied to represent the effect of a lower-level submodel input on a higher-level model response by aggregating the submodel SSA results across intermediate levels. A sufficient condition under which the simplified formulation provides an accurate solution is derived. To improve the accuracy of the GSSI formulation for a general situation, a modified formulation is proposed by including an Adjustment Coefficient (AC) to capture the impact of the nonlinearities of the upper level models. To save cost, the evaluation of the AC shares the same set of samplings used in the submodel SSA. The proposed HSSA method is examined through mathematical examples and a 3-level hierarchical model used in vehicle suspension systems design.
Non-Dominated Sorting Genetic Quantum Algorithm for Multi-Objective Optimization
Authors: Khorsand Amir-R. , Wang G. Gary , Raghavan J.
Published: May 2009

This paper presents a new multi-objective optimization method, which is inspired from the idea of non-dominated sorting genetic algorithm (NSGA) and genetic quantum algorithm (GQA). The GQA has been tested on well known test beds in single objective optimization and compared with the genetic algorithm (GA) in the lead author’s previous work [22]. This paper aims to apply the idea of GQA to multi-objective optimization (MOO). The developed method is called non-dominated sorting genetic quantum algorithm (NSGQA). The developed method is tested with benchmark problems collected from literature, which have characteristics representing various aspects of a MOO problem. Test results show that NSGQA has better performance on most benchmark problems than currently popular MOO methods such as the NSGA. The integration of GQA with MOO, and the systematic comparison with other MOO methods on benchmark problems, should be of general interest to researchers on MOO and to practitioners using MOO methods in design.
Multibody Molecular Dynamics II: Applications and Results
Authors: Mukherjee Rudranarayan M. , Crozier Paul , Anderson Kurt S.
Published: May 2009

This is the second paper in a series of two papers on using multibody dynamics algorithms and methods for coarse grained molecular dynamics simulations. In the previous paper, the theoretical discussions on this topic have been presented. This paper presents results obtained from simulating several biomolecular and bulk materials using multibody dynamics algorithms. The systems studied include water boxes, alkane chains, alanine dipeptide and carboxyl terminal fragments of Calmodulin, Ribosomal, and Rhodopsin proteins. The atomistic representations of these systems include several thousand degrees of freedom and results of several nano-second simulations of these systems are presented. The stability and validity of the simulations are studied through conservation of energy, thermodynamics properties and conformational analysis. In these simulations, a speed up of an order of magnitude is realized for conservative error bounds. A discussion is presented on the open-source software developed to facilitate future research using multibody dynamics with molecular dynamics.
Modeling and Simulation of Fuel Cell Elevator Backup Power Systems Using Advanced Vehicle Simulator
Authors: Zhou Yuliang Leon , Dong Zuomin
Published: May 2009

With limited available space in the city and increasing land cost, multi-storey and high-rise buildings now dominate most urban areas of the world. The irresistible trend to build taller and taller buildings to leverage increasing land cost turns elevator from a tool of convenience to a necessity of life. This dependence of elevator further requires its continuous function in spite of power failure caused by a variety of reasons. Reliable and effective elevator power backup system becomes an urgent need today. In this work, advanced electric power backup technologies, including battery, ultracapacitor and hydrogen fuel cells, are examined. To design a functional elevator backup power system, and to assess the feasibility of a battery–ultracapacitor–fuel cell hybrid elevator backup power system with superior performance, the modeling and simulation of an elevator and its backup power system are carried out. Based on its resemblance to an electric vehicle traveling vertically, the elevator, its power need and performance are modeled using the MatLab/Simulink based hybrid vehicle design and analysis tool, ADvanced VehIcle SimulatOR (ADVISOR). The modeling and simulation provide guidelines for selecting and sizing energy storage and conversion devices. More importantly, the quantitative analysis allows complex battery–ultracapacitor–fuel cell hybrid backup power system to be optimized to reach the best potential of each components for a given elevator usage cycle. To explore the feasibility of wide commercial applications of this technology, the initial cost, maintain costs and reliability of the battery–ultracapacitor–fuel cell hybrid elevator backup power system are also discussed.
Diagonal Quadratic Approximation for Parallelization of Analytical Target Cascading
Authors: Li Yanjing , Lu Zhaosong , Michalek Jeremy J.
Published: May 2009

Analytical Target Cascading (ATC) is an effective decomposition approach used for engineering design optimization problems that have hierarchical structures. With ATC, the overall system is split into subsystems, which are solved separately and coordinated via target/response consistency constraints. As parallel computing becomes more common, it is desirable to have separable subproblems in ATC so that each subproblem can be solved concurrently to increase computational throughput. In this paper, we first examine existing ATC methods, providing an alternative to existing nested coordination schemes by using the block coordinate descent method (BCD). Then we apply diagonal quadratic approximation (DQA) by linearizing the cross term of the augmented Lagrangian function to create separable subproblems. Local and global convergence proofs are described for this method. To further reduce overall computational cost, we introduce the truncated DQA (TDQA) method that limits the number of inner loop iterations of DQA. These two new methods are empirically compared to existing methods using test problems from the literature. Results show that computational cost of nested loop methods is reduced by using BCD and generally the computational cost of the truncated methods, TDQA and ALAD, are superior to other nested loop methods with lower overall computational cost than the best previously reported results.
A New Mobility Formula for Spatial Mechanisms
Authors: Wampler Charles , Larson Blake T. , Erdman Arthur G.
Published: May 2009

A new formula for predicting the mobility of spatial mechanisms is introduced. Instead of counting rigid links and the constraints between them, as is done in the usual Gru¨bler-Kutzbach formulae, we count vertices and edges in a polyhedral model of the mechanism. It is well known that the conventional formula underpredicts the mobility of certain exceptional classes of mechanisms, and in particular, does not easily accommodate compound spatial mechanisms that contain planar or spherical sub-mechanisms. The new approach provides a correct mobility whenever the conventional formula does and accounts for planar and spherical sub-mechanisms in a simple manner. Additionally, we present simple modifications to correctly model certain mechanisms that have remote spherical centers. We illustrate the method on compound mechanisms constructed from scissors linkages.
Dynamics of Chain CVT Drives: Effects of Friction Characteristic
Authors: Srivastava Nilabh , Haque Imtiaz U.
Published: May 2009

A chain CVT is a type of friction-limited continuously variable transmission that provides a continuum of gear ratios with fewer moving parts. The dynamic performance and torque capacity of a chain CVT drive rely significantly on the friction characteristic of the contact patch between the chain and the pulley. Since the friction characteristic of the contact patch may vary in accordance with the loading and design configurations, it is crucial to study the influence of friction characteristic on the performance of a CVT. Two different mathematical models of friction, which characterize different operating/loading conditions, are embedded into a detailed planar multibody model of chain CVT in order to understand the various friction-induced effects in the system. The mathematical models, the computational scheme, and the results corresponding to different loading scenarios are discussed. The results discuss the influence of friction characteristics on the dynamic performance, the axial force requirements, and the torque transmitting capacity of a chain CVT drive.
Modeling Uncertainty Reduction in Concurrent Engineering Design Teams
Authors: Barrientos Francesca A. , Tumer Irem Y. , Ullman David G.
Published: May 2009

The design process can be viewed as a series of actions for reducing uncertainty in product or system design specifications. At the beginning of the design process, uncertainty is high because the design space has yet to be explored and decisions have not been made. This uncertainty contributes to design risk, risk due to the engineer’s lack of knowledge and/or information. In design teams, design risk takes on the added dimension of lack of group awareness about the state of knowledge of each team member. To better understand and capture uncertainty inherent in early design, we have developed a methodology to model design evolution in concurrent design teams. The representation is a directed graph that represents the state of a design over time. In this paper we describe our modeling methodology and present a case study of two different design teams. We present the results of modeling a part of the design process. Then we show how the model can be analyzed to understand how information and knowledge transfer was used to make decisions and reduce uncertainty and design risk.
Cable-Driven Parallel Mechanisms: Application to a Locomotion Interface
Authors: Perreault Simon , Gosselin Cle´ment M.
Published: May 2009

Over the last decade, cable-driven parallel mechanisms have been used for several purposes. In this paper, a novel application is proposed, namely, using two 6-DOF cable-driven parallel mechanisms sharing a common workspace to obtain the mechanical base for the design of a locomotion interface. The methodology used to develop the architecture of the mechanisms is presented and the two main criteria used to optimize the geometry are described. These criteria are based on the Wrench-Closure Workspace (WCW) and a detection of the mechanical interferences between all the entities of the locomotion interface (cables and moving bodies). Then, the final design is described and its performances are given. Finally, in order to validate the relevance of the mechanism for the locomotion interface’s design, tensile forces in the cables are computed to observe maximal values reached during a typical human gait trajectory.
Empirical Models for Non-Deterministic Simulation-Based Robust Design
Authors: Choi Hae-Jin , Allen Janet K.
Published: May 2009

We propose a method for metamodeling non-deterministic computer intensive simulations for use in robust design. Generalized linear models for mean responses and heteroscadastic response variances are iteratively estimated in an integrated manner. Estimators that may be used for predicting the mean and variance models are introduced and metamodels of variance are developed. The usefulness of this metamodeling approach in efficient uncertainty analyses of non-deterministic, computationally-intensive simulation models for robust design methods is illustrated with the example of the design of a linear cellular alloy heat exchanger with randomly distributed cracks in the cell walls.
Application of MR Damper in Structural Control Using Genetic Algorithm and Fuzzy Logic PID Tuning Methods
Authors: Gu Zhiqiang , Oyadiji S. Olutunde
Published: May 2009

In this paper, the application of MR damper in structure control using PID tuning based on genetic algorithms and fuzzy logic is developed and used to control the vibrations of based-excited linear and nonlinear single degree-of freedom-systems, which represent building structures subjected to earthquake loading and are excited by means of the El Centro earthquake. For GA method, the fitness function, which is based on these three constraint conditions: the control variable, the error and the rise-time, is chosen in order to apply genetic algorithms to optimize the coefficients of a PID controller. For the fuzzy control, the PID parameters are found using fuzzy self-tuning for the fuzzy logic relationship between the parameters of PID control and the controller input variables e and ec . The adaptive fuzzy PID control, which uses the error e and the change of the error ec as the input variables, modifies the three PID parameters on line based on the fuzzy control principle. The Bouc-Wen model of MR damper is used to simulate the MR damper characteristics. The simulation results demonstrate that the MR damper, used in conjunction with PID tuning control is effective for controlling the vibration of the structure.
Innovative Six Sigma Design Using the Eigenvector Dimension-Reduction (EDR) Method
Authors: Wells Lee J. , Youn Byeng D. , Xi Zhimin
Published: May 2009

This paper presents an innovative approach for quality engineering using the Eigenvector Dimension Reduction (EDR) Method. Currently industry relies heavily upon the use of the Taguchi method and Signal to Noise (S/N) ratios as quality indices. However, some disadvantages of the Taguchi method exist such as, its reliance upon samples occurring at specified levels, results to be valid at only the current design point, and its expensiveness to maintain a certain level of confidence. Recently, it has been shown that the EDR method can accurately provide an analysis of variance, similar to that of the Taguchi method, but is not hindered by the aforementioned drawbacks of the Taguchi method. This is evident because the EDR method is based upon fundamental statistics, where the statistical information for each design parameter is used to estimate the uncertainty propagation through engineering systems. Therefore, the EDR method provides much more extensive capabilities than the Taguchi method, such as the ability to estimate not only mean and standard deviation of the response, but also the skewness and kurtosis. The uniqueness of the EDR method is its ability to generate the probability density function (PDF) of system performances. This capability, known as the probabilistic “what-if” study, provides a visual representation of the effects of the design parameters (e.g., its mean and variance) upon the response. In addition, the probabilistic “what-if” study can be applied across multiple design parameters, allowing the analysis of interactions among control factors. Furthermore, the implementation of the probabilistic “what-if” study provides a basis for performing robust design optimization. Because of these advantages, it is apparent that the EDR method provides an alternative platform of quality engineering to the Taguchi method. For easy execution by field engineers, the proposed platform for quality engineering using the EDR method, known as Quick Quality Quantification (Q3), will be developed as a Microsoft EXCEL add-in.
Applying Lean Manufacturing Principles to Revolutionize Cubrside Equipment and Collection Processes
Authors: Smith Edward W. , Johnston P. Judson , Summers Joshua D.
Published: May 2009

The application of lean manufacturing principles has improved the production flow of manufacturing companies across the globe. In a similar vein, environmentally conscious design has been an increasingly important avenue of research which similarly seeks to reduce waste and thereby mitigate environmental impact. An analysis of the curbside municipal solid waste (MSW) and recycling collection process from a lean manufacturing standpoint reveals numerous non-value added activities which can be eliminated or reduced and value-added activities which can be made more efficient. Environmental America Inc. (EAI) has proposed a collection process which will improve the overall material flow through the use of a collection vehicle specializing in the combined collection of raw waste and recyclable waste. This collection vehicle, combined with localized, low-impact material offloading facilities has the potential to revolutionize the curbside collection process. Our research supports this vision by configuring the truck layout and process operations, as discussed in this paper.
A Comparison of Three Passive Capture Mechanisms for Tether Momentum Exchange
Authors: Canfield Stephen L. , Chlarson Daniel L. , Sorensen Kirk
Published: May 2009

The Momentum-exchange/electrodynamic reboost (MXER) tether system has been proposed as a highly fuel-efficient means to enable high-energy missions to the Moon, Mars and beyond by serving as an “upper stage in space”. The MXER tether system combines electrodynamic propulsion via a conducting tether with energy storage and a transfer mechanism to boost spacecraft from low Earth orbit to a high-energy orbit quickly, like a high-thrust rocket. One of the significant challenges in developing a momentum-exchange/electrodynamic reboost tether system is the design of a mechanism that will enable a high speed rendezvous and docking process in an energy efficient manner [1]. This paper will review two elements of the process of developing an appropriate mechanism to accommodate the MXER tether capture process. The paper will begin with the derivation of a qualitative and quantitative description about the nature of the capture window due to parameteric uncertainties in the MXER tether. The paper will then present a several candidate capture mechanisms and will evaluate their performance relative to the kinematic and dynamic aspects of performing the capture process.
Wavelet-Based Structural Damage Detection
Authors: Zhong Shuncong , Oyadiji S. Olutunde
Published: May 2009

In this paper, a new wavelet-based approach for crack identification in beam-like structures is presented and applied to simply-supported beams with single or multiple cracks. A novel damage index, based on finding the difference between two sets of detail coefficients obtained by the use of the Stationary Wavelet Transform (SWT) of two reconstructed sets of modal displacement data of the cracked beam-like structure, is proposed for single crack detection or multiple crack detection. These two sets of mode shape data represent the left half and the modified right half of the modal data of the structure. Currently, SWT is widely used in the field of image processing for image noise reduction and image quality improvement. However, because it can provide an accurate estimate of the variances at each scale and facilitate the identification of salient features in a signal, SWT has great potential in the field of structural damage detection. In this paper, the modal responses of the damaged simply supported beams used are computed using the finite element method (FEM). The modal data generate is decomposed by SWT into a smooth curve, called approximation coefficient, and detail coefficient. It is shown that the detail coefficient includes crack information that is useful for structural damage detection. Therefore, a novel damage index, the difference of the SWT detail coefficients of two reconstructed sets of modal displacement data, is proposed and employed. The numerical simulation results show that the proposed wavelet-based method has a good anti-noise ability and it does not require the modal parameters of an intact structure as a baseline for crack detection. Therefore, it can be recommended for real applications in structural health monitoring and damage detection.
Identifying the Critical Points of Skeleton-Based Convolution Surfaces for Conceptual Design
Authors: Ma Guohua , Crawford Richard H.
Published: May 2009

Skeletal modeling is an approach to creating solid models in which the engineer designs with lower dimensional primitives such as points, lines, and triangles. The skeleton is then “skinned over” to create the surfaces of the three dimensional object. Convolution surfaces are generated by convolving a kernel function with a geometric field function to create an implicit surface. Certain properties of convolution surfaces make them attractive for skeletal modeling, including: (1) providing analytic solutions for various geometry primitives (including points, line segments, and triangles); (2) generating smooth surfaces (3) and providing well-behaved blending. We assume that engineering designers expect the topology of a skeletal model to be identical to that of the underlying skeleton. However the topology of convolution surfaces can change arbitrarily, making it difficult to predict the topology of the generated surface from knowledge of the topology of the skeleton. To address this issue, we apply Morse theory to analyze the topology of convolution surfaces by detecting the critical points of the surface. We describe an efficient algorithm that we have developed to find the critical points by analyzing the skeleton. The intent is to couple this algorithm with appropriate heuristics for determining parameter values of the convolution surface that will force its topology to match that of the skeleton.
A Simulation Framework for Robotic System Design
Authors: Wilkie David , Primerano Richard , Regli William
Published: May 2009

This paper proposes a framework for the physically based modeling of robotic systems. The framework focuses on integrating a mechanical engineering assembly model with an electrical engineering controller model in a co-simulation. The simulated results can be used for the evaluation of robotic system designs. This paper surveys existing algorithms and software packages that could be used to implement the framework. The framework is illustrated using a biologically inspired robot as a case-study.
A Magnetorheological Actuation System - Part II: Modeling
Authors: John Shaju , Chaudhuri Anirban , Wereley Norman M.
Published: May 2009

There is a demand for hybrid actuation systems which combines actuation and valving systems in a compact package. Such self-contained actuation systems can be used in the field of rotorcraft as active pitch links and in the field of automotive engineering as active vibration control devices. MR fluids can be used in valves to control the motion of an output cylinder. Such a valving system will have no moving parts and thus can be used in applications where there is high centrifugal loading. In the current setup, MR valves are configured in the form of a Wheatstone bridge and bidirectional motion is produced in the output cylinder by alternate application of magnetic field in the arms of the wheatstone bridge. The actuation is performed using a compact Terfenol-D stack driven actuator. The frequency rectification of the stack motion is done using reed valves. This actuator and valve configuration form a compact hydraulic system with fluidic valves. The advantages of such systems are low parts count, absence of moving parts and the ability to control the motion of the output cylinder by controlling the fluid flow through the MR valves. By the application of different magnetic fields to the arms of the bridge (by applying different currents to the magnetic circuits), we can control the differential pressure seen by the output cylinder. This add the capability of designing controllers for the system. This work concentrates on the modeling of the entire actuation system performance. The results of the modeling effort is then compared with experimental results. The system is modeled by ordinary differential equations governing the motion of the active stack, fluid in the different sections and the output cylinder shaft. The rheological properties of the MR fluid is modeled using both Bingham plastic and bi-viscous models.
Effects of a Cracked Blade on Mistuned Turbine Engine Rotor Vibration
Authors: Saito Akira , Castanier Matthew P. , Pierre Christophe
Published: May 2009

An efficient methodology for predicting the nonlinear forced vibration response of a turbine engine rotor with a cracked blade is presented and used to investigate the effects of the damage on the forced response. The effects of small, random blade-to-blade differences (mistuning) and rotation on the forced response are also considered. Starting with a finite element model, a hybrid-interface method of Component Mode Synthesis (CMS) is employed to generate a reduced-order model (ROM). The crack surfaces are retained as physical degrees of freedom in the ROM so that the forces due to contact interaction in three-dimensional space can be properly calculated. The resulting nonlinear equations of steady-state motion are solved by applying an alternating frequency/time-domain method, which is much more computationally efficient than traditional time integration. Using this reduced-order modeling and analysis framework, the effects of the cracked blade on the system response are investigated for various mistuning levels and rotation speeds. First, the advantages of the selected hybrid-interface CMS method are discussed and demonstrated. Then, the resonant frequency shift associated with the stiffness loss due to the crack, as well as vibration localization about the cracked blade are thoroughly investigated. In addition, the results of the nonlinear ROMs are compared to those obtained with linear ROMs as well as blade-alone ROMs. It is shown that several key system vibration characteristics are not captured by the simpler models, but that some insight into the system response can be gained from the blade-alone response predictions. Furthermore, it is demonstrated that while the effects of the crack often appear similar those of mistuning, differences between the effects of mistuning and damage can be discerned by observing and comparing the response across different families of system modes.
An Efficient Sensing Localization Algorithm for Free-Form Surface Digitization
Authors: Huang Yunbao , Qian Xiaoping
Published: May 2009

This paper presents a divide-and-conquer method that finds a near-optimal distribution of sensing locations in a very efficient manner for the free-form surface digitization process. We formulate the sensing localization issue as a next-best-point problem. We transform the uncertainty of a reconstructed B-spline surface into a higher-dimensional uncertainty surface. This further allows the use of convex hull and subdivision properties of B-spline surfaces in the NBP based sensing localization algorithm. It thus dramatically reduces the search time for determining the next best sensing location. Experimental examples demonstrate that the algorithm compares favorably to existing algorithms and, due to its high efficiency, supports both off-line and on-line sensing planning.
Annotation for Enterprise Information Management Traceability
Authors: Sarraipa Joao , Zouggar Nabila , Chen David , Jardim-Goncalves Ricardo
Published: May 2009

Enterprise modeling has been considered effective for enterprise integration and engineering. Model traceability is the characteristic in which a model is clearly linked to its source and to the outputs created during the model life cycle. As enterprise models change over time, to ensure better interoperability between systems and organizations it is necessary to trace these changes. Thus, the adoption of an annotation technique for enterprise model traceability seems adequate. This paper proposes a novel methodology for enterprise modeling traceability using annotation technique in order to record the model changes during its life cycle. This methodology is organized in five steps: problem definition, model formulation, model solution, model interpretation and model maintenance. The paper concludes by a case study highlighting the concepts presented on enterprise model traceability and demonstrating the usefulness of the proposed approach to develop enterprise model interoperability during the model life cycle.
Switchgear Component Commonality Design Method Considering Delivery Lead-Time and Inventory Level
Authors: Kariya Haruki , Izui Kazuhiro , Nishiwaki Shinji , Yoshimura Masataka , Ogihara Yoshiya , Hayashi Shuichi
Published: May 2009

Product families are groups of related products that take advantage of part commonalities at various levels to streamline delivery of maximal product variety with minimal cost impact and as short as possible lead-times. This paper proposes a new integrated product design method for build-to-order production system based products, using the product family concept, which considers product performance, delivery lead-time and inventory cost. The development and discussion of this method uses a switchgear design problem as a concrete and practical design case. A build-to-order production system has been applied to switchgear manufacturing due to its small-scale production and a variety of customer requirements. However, if the risk of maintaining unsold inventory can be decreased, manufacturers can justify holding an amount of versatile inventory. In this paper, inventory production system is applied to the switchgear production problem to shorten the delivery lead-time. The switchgear design and production problem is formulated using three objective functions, which are subassembly procurement lead-time, inventory cost and area occupied by various switchgear configurations. Moreover, to assist inventory cost evaluations, a simulation procedure for the inventory system is proposed. The proposed method is used to obtain a Pareto optimal solution set of the three objective functions. Finally, an example switchgear design problem is solved to illustrate that optimal use of component commonalities across different modules can significantly reduce inventory costs, while also shortening product delivery lead-times.
Optimum Curve Matching Between Two Free-Form Curves for Modeling and Manufacturing
Authors: Samanta Kuntal , Koc Bahattin
Published: May 2009

A new curve matching method is proposed to generate non-self-intersecting and non-twisted ruled surfaces for application in diverse fields such as heterogeneous object modeling, layered manufacturing, offsetting and multi-axis NC machining. The method establishes point-to-point correspondence represented by a set of ruling lines between two directrices of the ruled surface. The directrices are given as non-self-intersecting, closed, at least C1 continuous, planar, B-spline curves. To match the points on the directrices, a heuristic optimization method developed with the objective is to maximize the sum of the inner products of the unit normals at the end points of the ruling lines and minimize the sum of the lengths of connecting ruling lines. The generated ruling lines can be used as cutter location data for multi-axis NC machining of ruled surfaces. Moreover, by subdividing the ruling lines into equal number of segments, one can construct a series of intermediate piecewise linear curves that represent the metamorphosis between the directrices. Implementation and examples are also presented.
A Comparative Study of Actively Controlled and Shunted Piezoelectric Materials for Structural Damping
Authors: Ahmadian Mehdi
Published: May 2009

A comparison between actively-controlled piezoelectric (PZT) material with positive position feedback (PPF) and a parallel resistor-inductor shunt circuit technique is provided. This study focuses on the performance of each technique at reducing structural vibration on a test plate for both narrowband and broadband frequency reductions. The comparison between the shunted and active PZT damping techniques used in this study shows that active control with positive position feedback was more effective at controlling vibrations of a test plate. The active PZT method was able to add damping to each of the modes targeted in the frequency range of interest. In addition, active control with positive position feedback was able to achieve this level of control authority with a single PZT patch located in the center of the test plate. Conversely, shunted PZTs used three PZT actuators to reduce the test plate vibrations. The results show that actively-controlled PZTs can provide much more damping per square area of PZT than shunted PZTs, by as much as four times more.
A Distributed Vision Infrastructure for Multi-Robot Localization
Authors: Stancil Brian , Hsieh Hsiang-Wen , Chen Tsuhan , Yu Hung-Hsiu
Published: May 2009

Localization is one of the critical issues in the field of multi-robot navigation. With an accurate estimate of the robot pose, robots will be able to navigate in their environment autonomously with the aid of flexible path planning. In this paper, the infrastructure of a Distributed Vision System (DVS) for multi-robot localization is presented. The main difference between traditional DVSs and the proposed one is that multiple overhead cameras can simultaneously localize a network of robots. The proposed infrastructure is comprised of a Base Process and Coordinate Transform Process. The Base Process receives images from various cameras mounted in the environment and then utilizes this information to localize multiple robots. Coordinate Transform Process is designed to transform from Image Reference Plane to world coordinate system. ID tags are used to locate each robot within the overhead image and camera intrinsic and extrinsic parameters are used to estimate a global pose for each robot. The presented infrastructure was recently implemented by a network of small robot platforms with several overhead cameras mounted in the environment. The results show that the proposed infrastructure could simultaneously localize multiple robots in a global world coordinate system with localization errors within 0.1 meters.