bluuebunny/crossref_metadata_2025 huggingface dataset:
Order Reduction of Parametrically Excited Nonlinear Systems Subjected to External Periodic Excitations
Authors: Redkar Sangram , Sinha S. C.
Published: July 2010

In this work, some techniques for order reduction of nonlinear systems with periodic coefficients subjected to external periodic excitations are presented. The periodicity of the linear terms is assumed to be non-commensurate with the periodicity of forcing vector. The dynamical equations of motion are transformed using the Lyapunov-Floquet (L-F) transformation such that the linear parts of the resulting equations become time-invariant while the forcing and/or nonlinearity takes the form of quasiperiodic functions. The techniques proposed here; construct a reduced order equivalent system by expressing the non-dominant states as time-varying functions of the dominant (master) states. This reduced order model preserves stability properties and is easier to analyze, simulate and control since it consists of relatively small number of states in comparison with the large scale system. Specifically, two methods are outlined to obtain the reduced order model. First approach is a straightforward application of linear method similar to the ‘Guyan reduction’, the second novel technique proposed here, utilizes the concept of ‘invariant manifolds’ for the forced problem to construct the fundamental solution. Order reduction approach based on invariant manifold technique yields unique ‘reducibility conditions’. If these ‘reducibility conditions’ are satisfied only then an accurate order reduction via ‘invariant manifold’ is possible. This approach not only yields accurate reduced order models using the fundamental solution but also explains the consequences of various ‘primary’ and ‘secondary resonances’ present in the system. One can also recover ‘resonance conditions’ associated with the fundamental solution which could be obtained via perturbation techniques by assuming weak parametric excitation. This technique is capable of handing systems with strong parametric excitations subjected to periodic and quasi-periodic forcing. These methodologies are applied to a typical problem and results for large-scale and reduced order models are compared. It is anticipated that these techniques will provide a useful tool in the analysis and control system design of large-scale parametrically excited nonlinear systems subjected to external periodic excitations.
Fault Recognition in the Presence of Error With NURBS-Based Metamodels
Authors: Turner Cameron J.
Published: July 2010

Condition-based maintenance (CBM) offers the possibility of replacing the predominant maintenance-as-scheduled paradigm with a maintenance-on-demand paradigm. In all CBM algorithms, faults must first be recognized, then characterized and finally reconciled. Multiple CBM methods have been proposed, including model-free, model-based and metamodel-based methods. However, the signals from real systems are obscured by sources of error. This research examines the impact of error upon a metamodel-based CBM approach using a simulated system to reveal the significance of error in the all-important step of fault recognition. The use of a simulated system allows control of the type and magnitude of both the error and of the fault signals allowing their significance to be evaluated. As a result of this research, a stronger theoretical foundation metamodel-based CBM techniques is established and several promising behaviors are identified.
A Portable Computational Cluster for Modeling and Simulation
Authors: Michopoulos J. G. , Zaruba G. V.
Published: July 2010

In the present paper we are describing the development of a portable computational cluster infrastructure based on Apple’s MacMini systems. The objective of this effort is to initiate the exploration of the feasibility for building and evaluating a low cost computational cluster system that could be portable due to the small form factor of the individual units while it could still provide considerable computational scalability. Here we outline our experiences in the form of a how-to methodology for setting up a MAC OS X 10.4 cluster for Xgrid and three popular versions of Message Passing Interface (MPI), i.e., OpenMPI, LAM-MPI, and MPICH2. Subsequently, we describe some performance measurements through the utilization of the Fire Dynamic Simulator (FDS) for two cases of reactive flow topologies. Finally, Xgrid with OpenMPI throughput and latency performance results are presented and discussed.
Harvesting Energy From the Nonlinear Oscillations of a Bistable Piezoelectric Inertial Energy Generator
Authors: Stanton Samuel C. , Mann Brian P.
Published: July 2010

Piezoelectric materials constitute an efficient transduction medium for passive power generation from ambient vibrations. As such, the unimorph and bimorph piezoelectric laminate linear beam is a prolifically researched energy harvesting device. The linear modeling framework is amenable to analytical solutions and frequency matching inertial energy generators to environmental oscillations is a seemingly ideal solution. Realistically, however, environmental disturbances are rarely of one particular frequency and linear oscillators are capable of strong responses only within a limited frequency range about system resonance. In view of these shortcomings, this paper builds upon a new research direction and shift in design philosophy toward purposefully incorporating nonlinearity into energy harvesting systems. In particular, the nonlinear magnetic forces of repulsion are introduced at the free end of a cantilevered bimorph piezoelectric beam, where the separation distance between two opposing permanent magnets doubles as a controllable bifurcation parameter. The numerical results demonstrate the efficacy of the nonlinear responses to yield markedly increased power levels when subject to deterministic excitations of varying forcing frequency and amplitude.
Stability of a Submerged Deformable Body
Authors: Jing Fangxu , Kanso Eva
Published: July 2010

We study the stability of passive motion of a fish model. The (articulated body) fish model accounts for the finite dimensions of the fish, its bending stiffness (via the torsional springs at the joints), the unsteadiness of the flow (via the added mass effect) but it does not take into consideration vortex shedding from the trailing edge of the fish. The stability analysis shows that there is a range of parameter values (bending stiffness versus body dimensions) that support stable passive swimming in the direction of the body’s length.
Dynamic Characteristics of Nonlinear Elastics Rotor-Bearing System With Coupling Faults of Pedestal Looseness and Rub-Impact
Authors: Luo Yuegang , Zhang Songhe , Ren Zhaohui , Wen Bangchun
Published: July 2010

A dynamic model of the nonlinear elastics rotor-bearing system with coupling faults of pedestal looseness and rub-impact was set up, taking the linearity and cube item as the physics nonlinear factors. The complex characteristics of the rotor-bearing system were numerically studied. There exists complex nonlinear motion of periodic, quasi-periodic and chaotic in the response of the system. The main motions of the rotor-bearing system with rub-impact fault are periodic-2, periodic-4 and quasi-periodic within the super-critical speed range, but it with coupling faults of pedestal looseness and rub-impact are periodic-3 and chaotic. The influence of oil-film force to the rotor system is weakened by the pedestal looseness fault. The results may bring up theoretical references for fault diagnoses, dynamic design, and security running to rotor-bearing system.
A Highly Parallel Approach to Meshing Scattered Point Data
Authors: Sheung Hoi , Mok Siu-Ping , Wang Charlie C. L.
Published: July 2010

In this paper, we present a parallel mesh surface generation approach for unorganized point clouds that runs on the graphics processing unit (GPU). Our approach integrates point cloud simplification, point cloud optimization, and local triangulation techniques into the same framework. The input point cloud will be processed through three steps of algorithms, which are 1) preprocessing: to generate the neighborhood table of points and estimate the normal vectors, 2) clustering: to group points into optimized clusters that minimize the shape approximation error, and 3) meshing: to connect the seed points in clusters to form the resultant triangular mesh surface. As the number of clusters can be specified by users, the number of vertices on resultant mesh surfaces is controlled. The algorithms exploited here are highly parallelized to take advantage of the single-instruction-multiple-data (SIMD) parallelism that is available on consumer-level graphics hardware with GPU. Moreover, to overcome memory limitation on graphics hardware, the algorithms in all these steps are able to process massive data in streaming mode.
Backstepping Control of Fractional-Order Chen System
Authors: Naseri E. , Ranjbar A. , HosseinNia S. H.
Published: July 2010

In this paper, Chaos and its control is studied in fractional-order Chen system. Backstepping method is proposed to synchronize two identical fractional-order Chen systems. The simulation results show that this method can effectively synchronize two identical chaotic systems.
New Insight Into Energy Harvesting via Axially-Loaded Beams
Authors: Daqaq Mohammed F.
Published: July 2010

Driven by the study of Leland and Wright [1], this manuscript delves into the qualitative understanding of energy harvesting using axially-loaded beams. Using a simple nonlinear electromechanical model and the method of multiple scales, we study the general nonlinear physics of energy harvesting from a piezoelectric beam subjected to static axial loading and traversal dynamic excitation. We obtain analytical expressions for the steady-state response amplitude, the voltage drop across a resistive load, and the output power. We utilize these expression to study the effect of the axial loading on the overall nonlinear behavior of the harvester. It is demonstrated that, in addition to the ability of tuning the harvester to the excitation frequency via axial load variations, the axial load aids in i) increasing the electric damping in the system thereby enhancing the energy transfer from the beam to the electric load, ii) amplifying the effect of the external excitation on the structure, and hence, increases the steady-state response amplitude and output voltage, and iii) increasing the bandwidth of the harvester by enhancing the effective nonlinearity of the system.
Active Vibration Reduction to Optimize the Grinding Process
Authors: Boldering Alexander L. , Simnofske Marc , Raatz Annika , Hesselbach Ju¨rgen
Published: July 2010

High production quality and processing velocity characterizes an efficient machine tool. Higher velocities lead to increasing process forces, hence the stiffness of the machine must be high. Especially in grinding, the dynamic stiffness of a machine influences the process stability enormously. The stability of the grinding process is affected by the specification of the grinding wheel, machine parameters and the condition of the workpiece. Chattering is simply a consequence of vibration within a grinding system. At present, parts of the machine tools (structures, drives, measuring systems, etc.) are constantly being improved. However, a better performance can only be achieved by applying innovative basic approaches. In this paper, a grinding machine with integrated active modules is presented. The aim of the modules, which consist of piezo actuators and force transducers, is to increase the static and dynamic stiffness of the structure and minimize vibrations.
Instrumental Variable Method for Identifying Fractional Box-Jenkins Models
Authors: Victor Ste´phane , Malti Rachid , Oustaloup Alain
Published: July 2010

This paper deals with continuous-time system identification using fractional differentiation models in a colored noisy output context. An optimal instrumental variable method for identifying hybrid fractional Box-Jenkins models is described. The relationship between the measured input and the output is a fractional continuous-time transfer function, and the noise is a discrete-time AR or ARMA process. The method is illustrated on a simulation example.
Autonomous Robotic Vehicle (Robicle) With Ambient Intelligence
Authors: Ryoo Young-Jae , Chang Young-Hak , Lim Dae-Yeong , Lee Yong-Jun
Published: July 2010

Magnetic sensing is a reliable technology that has been developed for the purposed of position measurement and guidance, especially for applications in autonomous robotic vehicles. To calculate a position of a magnetic guidance road, it should be estimated in real-time. While the capability of a microprocessor and memory spaces have the limitation in implementation. To solve the above problems, this paper proposes a new structure of the magnetic sensors included a vertical magnetic field. The proposed method uses the linear region of the sensor output, and position determination using a simple equation with a microcontroller. The position sensing technique was implemented in the guidance of autonomous vehicle. The test results show that position sensing can be useful for an autonomous robotic vehicle.
A Systematic Approach to the Reliability Analysis of an n-Unit Warm Standby System With k-Repair Facility
Authors: Pang Yu , Huang Hong-Zhong , Liu Yu , Xie Min
Published: July 2010

A systematic reliability analysis of n-unit warm standby repairable system with k-repair facility is presented in this paper. Traditional approaches are extended under the following assumptions: (1) the working lifetime, the standby lifetime, and the repair time of failed units are represented as exponential distribution; and (2) the repair of failed units are as good as new after repair. In this paper, a general reliability analysis of an n-unit warm standby repairable system with k-repair facility is presented. Based on previous analysis, the steady-state reliability and the average availability of the system are formulated using the Markov process theory and Laplace transform.
Psychological Information Entropy and Its Applications to Reliability Engineering
Authors: Wang Guibao , Sun Liansheng , Li Haiqing , Huang Hong-Zhong
Published: July 2010

In general, information contains both of the physical attributes and the psychological attributes. For these two kind attributes of information, this paper discussed the incompleteness of the axioms system of the current information entropy theories. It is necessary to add the condition of boundedness to the axioms system when it is used to measure the uncertainty of psychological information. A new family of information entropy using a convex-concave function is introduced for satisfying the psychological attributes of information. And based on the psychological information entropy function, the divergence measures between two probability distributions of psychological information defined as Wang-Huang divergences are formulated. For the boundedness attributes of the psychological information entropy function and not requiring the condition of absolute continuity to be satisfied by the probability distributions involved, Wang-Huang divergences are totally different with the Kullback-Leiber divergences. The new measures are well characterized by the properties of non-negativity, finiteness. More importantly, their close relationship with the variation and the probability of misclassification error are established in terms of bounds illustrated in numerical examples. These bounds are crucial in many applications of divergence measures such as in the quality and reliability engineering applications.
Numerical Method for Solving Fractional Optimal Control Problems
Authors: Biswas Raj Kumar , Sen Siddhartha
Published: July 2010

A numerical technique for the solution of a class of fractional optimal control problems has been proposed in this paper. The technique can used for problems defined both in terms of Riemann-Liouville and Caputo fractional derivatives. In this technique a Reflection Operator is used to convert the right Riemann-Liouville derivative into an equivalent left Riemann-Liouville derivative, and then the two point boundary value problem is solved numerically. The proposed method is straightforward and it uses an available numerical technique to solve fractional differential equations resulting from the formulation. Examples considered here show that the numerical results obtained using this and other techniques agree very well.
FunctionCAD: A Functional Modeling Application Based on the Function Design Framework
Authors: Nagel Robert L. , Perry Kenneth L. , Stone Robert B. , McAdams Daniel A.
Published: July 2010

This paper presents a functional modeling application, FunctionCAD, based on integrated functional and process modeling within the Function Design Framework. FunctionCAD provides for mixed, hierarchical models of environment, process and function with relationships represented via flows of material, energy and signal. This paper discusses the technical details of the FunctionCAD software including its two major components: (1) the library, libFCAD, for handling the internal representation of the model and (2) the GUI for user-based model manipulation and visualization. The application of FunctionCAD within a computational, function-based conceptual design process is discussed along with the plugin manager and interface that have been developed as a part of the FunctionCAD software to allow interconnectivity with existing conceptual design tools. And finally, a detailed description of model creation within the FunctionCAD environment is provided to illustrate software operability.
From System Identification to Path Planning Using Fractional Approach: A Thermal Application Example
Authors: Victor Ste´phane , Malti Rachid , Melchior Pierre , Oustaloup Alain
Published: July 2010

This paper presents a global fractional approach from system identification to path planning; these results will be applied to a typical fractional application: a thermal diffusion in an aluminium rod. The objective is to follow a desired path using fractional linear flatness. However, models of true systems are not always known. Through a black box identification using a fractional model, the temperature versus the heat flux of an aluminium rod is modeled. The coosrivcf algorithm enables to optimize as well the parameter coefficients and the commensurate order. The fractional flat output generates the input command so that the system follows that desired path.
Smith Predictor Embedded With Fractional Algorithms for the Control of a Heat Diffusion System
Authors: Jesus Isabel S. , Tenreiro Machado J.
Published: July 2010

In this paper we study the control of a heat diffusion system based on the application of the fractional calculus concepts. In this perspective, several algorithms are investigated and compared, when integrated within a Smith predictor structure. Simulations are presented assessing the performance of the proposed fractional algorithms.
Modeling and Torsional Vibration Analysis of an Engine Cold-Test Cell for Production Fault Diagnostics
Authors: Gul Kamran A. , Bilal Nasir , Adams Douglas E.
Published: July 2010

Engine cold-test cell drivelines experience large torsional oscillations in transient tests due to the excitation of system resonances by various engine harmonics. The excessive torsional vibrations result in structural degradation of the driveline components and also affect the fault detection process by preventing accurate measurement of gear noise and by compromising the quality of diagnostic torque waveforms. In this work, a torsional vibration model of an engine production cold-test cell is developed to analyze the vibration and diagnostic signal characteristics. The test cell driveline components are modeled using first principles. Waveform distortion metrics based on harmonic order amplitude ratios are devised to quantify signal distortion levels. A rigorous validation of the simulation model using both torque amplitude and waveform distortion comparisons of test and simulation data is conducted. Model parameters that can help suppress the torsional resonances in the operating range are identified through embedded sensitivity functions. It is shown that by modifying the inertia and stiffness properties of the rubber coupling, the resonant vibration problem of interest can be mitigated. The design modifications are implemented in a production test cell resulting in a significant reduction in torsional amplitudes and waveform distortion levels with a corresponding increase in the sensitivity to faults.
Analytical Approach on Nonlinear Vibration and Wave Response of Saturated Porous Media Subjected to Multiple Excitations
Authors: Dai Liming , Wang Guoqing
Published: July 2010

This research investigates the wave motions of a porous medium saturated by multiple immiscible fluids in porous media subjected to multiple external excitations, via an analytical and numerical approach. The findings of this research contribute to the comprehension of fluids and solid interactions in porous media excited by multiple energy sources. With the approach developed, the vibrations of any desired point and wave motion at desired domain can be quantitatively determined in terms of amplitude and frequency of the vibrating points and therefore the wave propagation in the domain. The relationships among the relative displacements, porosity of the porous medium, saturations of the fluids and the other system parameters are also studied quantitatively.
A Moving Horizon Based Sensor Fusion and Load Estimation Concept for Driving Profile - Based Operating Strategy Optimization in Hybrid Hydraulic Trucks
Authors: Kaszynski Martin , Sawodny Oliver
Published: July 2010

In this paper, a moving-horizon based concept for estimating the driving load profile of a hybrid hydraulic truck is proposed. First, a simple model of the hybrid hydraulic drivetrain is given. Based on this model and vehicle data, a sensitivity analysis is performed to determine which (time-varying) model parameters must be known to represent the driving load adequately. As a major contribution of this work, a Moving Horizon Estimation (MHE) scheme is developed to estimate mass and road grade from standard measurement data. Starting from an intuitive nonlinear formulation of the optimization task, the setup is then transformed to a constrained linear quadratic problem. It is shown how additional sensor information can be easily incorporated into the optimization framework to enhance the estimates, since an identifiability analysis shows that the parameters are usually not clearly distinguishable. Finally, it is demonstrated how the estimated load profile can be used to evaluate the fuel savings potential of a hybrid hydraulic truck by computing the fuel optimal operating strategy and comparing it to non-hybrid and rule-based strategies.
Damage Analysis and Prediction of Forming Limits for IF Steel
Authors: Huang Jing , Li Lijun , Li Zhida
Published: July 2010

Based on Continuum Damage Mechanics, an isotropic damage model is developed to give a damage-coupled localized necking criterion. Hill’s 1948 quadratic yield criterion and flow theory are employed to describe anisotropic plasticity of sheet metal during forming procedure. Sheet forming experiments in three stress states and density measurement test have been performed on IF steel, and then the damage data obtained are used to validate numerical results based on the damage-coupled model. As for the proportional loading, a simple expression of limit strains has been obtained to predict the forming limit curve. Then the forming limit diagrams predicted by this damage-coupled anisotropic model have been validated with experimental data for two kinds of sheet metal. Also the influences of material properties on forming limit curves are discussed.
Multiphysics Multi-Model Simulation of Large-Area Plasma Chemical Reactors
Authors: Krzhizhanovskaya Valeria , Ivanov Denis , Gorbachev Yuriy , Smirnov Alexander
Published: July 2010

Facing an ever-growing demand for large-area solar cells and flat-panel displays, the industry strives to produce larger, cheaper and better performing thin films. Computer simulation has proved to be a reliable and cost-efficient way to optimize existing technologies, to develop and test new ideas. The most widely used technology of thin film production is plasma enhanced chemical vapor deposition (PECVD), which involves multiple physical and chemical processes: electromagnetic wave propagation, plasma-chemical processes (ionization, dissociation, excitation, recombination, attachment, ion bombardment, etc.), convective and diffusive transport, thermal effects, gas-phase chemical reactions, heterogeneous reactions on the surface, and the target process of film growth. The temporal and spatial scales of these processes span many orders of magnitude (from nanoseconds to hours and from Angstrom to meters). Modeling these coupled processes with a fine level of detail and appropriate scale in three dimensions is still out of reach of modern computational resources; and special modeling and simulation approaches are required to meet the challenge [1].
Increasing Performance in Complex Product Development Through Structured Information and Cross-Functional Collaboration
Authors: Malvius Diana , Ivarsson Martin , Bergsjo¨ Dag
Published: July 2010

A joint comparison between two separate case studies is presented in this paper. The studies targeted an original equipment manufacturer (OEM) and a selected software supplier to the OEM. Two different measuring methods based on a quantitative and a qualitative approach were used in the compared studies. These two different perspectives are integrated by cross analysis and triangulation into a synthetic understanding of what problems are in common for the two companies and how these interrelate. The studies, with focus on information management issues aimed at identifying improvement areas for performance in product development. It is concluded that factors like cross-functional collaboration and information structure were targeted as areas for critical improvement in both case studies.
Discriminating Ambulation Using a Smart Sensing Plate
Authors: Elliott Mark T. , Ma Xianghong , Brett Peter N.
Published: July 2010

The automated sensing scheme described in this paper has the potential to automatically capture, discriminate and classify transients in gait. The mechanical simplicity of the walking platform offers advantages over standard force plates. There is less restriction on dimensions offering the opportunity for multi-contact and multiple steps. This addresses the challenge of patient targeting and the evaluation of patients in a variety of ambulatory applications. In this work the sensitivity of the distributive tactile sensing method has been investigated experimentally. Using coupled time series data from a small number of sensors, gait patterns are compared with stored templates using a pattern recognition algorithm. By using a neural network these patterns were interpreted classifying normal and affected walking events with an accuracy of just under 90%. This system has potential in gait analysis and rehabilitation as a tool for early diagnosis in walking disorders, for determining response to therapy and for identifying changes between pre and post operative gait.
Computer Simulation of Laser Annealing of a Nanostructured Surface
Authors: Ivanov Denis , Marinov Ilya , Gorbachev Yuriy , Smirnov Alexander , Krzhizhanovskaya Valeria
Published: July 2010

Laser annealing technology is used in mass production of new-generation semiconductor materials and nano-electronic devices like the MOS-based (metal–oxide–semiconductor) integrated circuits. Manufacturing sub-100 nm MOS devices demands application of ultra-shallow doping (junctions), which requires rapid high-temperature annealing to increase dopant electrical activation and remove implantation defects in the silicon [1].
Reliability of the Flexible Display STN LCD Based Environmental Test
Authors: Fan Pan-Dong , Miao Qiang , Yang Ping , Chen Quayle , Xue Tom , Xu Leon , Salo Antti
Published: July 2010

In recent years, the application of Flexible Display (FD) is increasing dramatically due to its high brightness, high contrast, and large angle of view. Also because the substrate polymer material is flexible, FD is easily and widely used in various electronic packages. The competition of products based on these technologies such as electronic paper and mobile screen can be improved. In most of these applications, failure of FD can directly lead to failure of device. However, reliability data on FD are not commonly available in published literature, and the reliability of FD in practical application has not been studied very well. This paper presents an experimental study of FD with focus on its reliability under varying temperature and humidity conditions. The purpose of this paper is to investigate the failure mode of FD based on environmental test including steady damp heat test, dry heat test, cyclic damp heat test and cold test. The failure modes are discussed and the analysis is presented. In this study, all tests are conducted with visual inspections during each test procedure.
Quantifying Nitrogen Status of Rice Using Low Altitude UAV-Mounted System and Object-Oriented Segmentation Methodology
Authors: Zhu Jinxia , Wang Ke , Deng Jinsong , Harmon Tom
Published: July 2010

Nitrogen deficiency can seriously reduce yield, while over-fertilization can result problems such as excess nutrient runoff and groundwater pollution. Hence, efficient methods for assessing crop nitrogen status are needed to enable more optimal fertilizer management. The ability to quantify the different nitrogen application rates by crops using digital images taken from an unmanned aerial vehicle (UAV) was investigated in comparison with ground-based hyperspectral reflectance and chlorophyll content data from 140 plots on a managed field. This research utilized new UAV system, comprised of remote-controlled helicopter (Hercules II) and digital camera (EOS 30D), was used to characterize spatial and temporal variation in crop production. Digital information was extracted based on an object-oriented segmentation method, and the color parameter was reduced and represented using principal component analysis (PCA). An estimating model was established after analyzing the relationship between the optimal color parameter and ground-based measurements. Model testing demonstrated that unknown samples could be associated with the controlled nitrogen application rates (0, 60, 90, and 120 kg N·hm−2): 91.6% %; N1 (60 kg N·hm−2): 70.83%; N2 (90 kg N·hm−2): 86.7%; N3 (120 kg N·hm−2): 95%. Overall, this result proved to provide a cost-effective and accurate way and the UAV was an exploratory and predictive tool when applied to quantify different status of nitrogen. In addition, it indicated that the application of digital image from UAV to the problem of estimating different nitrogen rates is promising.
Context Dependent Contact Preserving Off-Line Model Simplification for Interactive Rigid Body Dynamics Simulations
Authors: Thakur Atul D. , Gupta Satyandra K.
Published: July 2010

Rigid body dynamics simulations require use of accurate computation of contacts among bodies. Often collision detection algorithms are used for determining the contact between moving bodies. Many mechanical parts have a large number of features and hence collision detection with the detailed part models often slows down the rigid body dynamics simulations. Model simplification techniques developed for efficient graphical rendering may change the part geometry in such a manner that the contact points between parts may change as a result of the simplification. Hence, such simplifications may alter the resulting simulated behavior. In many simulation scenarios, all the parts participating in the simulation are known in advance. In such cases, the simulation context (i.e., a priori knowledge of parts) can be exploited to simplify the part geometries such that the contact points among parts do not change. For example, parts with significant concavities may have regions on their boundaries that will be inaccessible to other parts in the simulation and hence contact points cannot lie on such inaccessible regions. Removing such regions from the parts can simplify the model and hence speed up the simulation for interactive applications.
Design of Flexible Skin for Target Displacements Based on Meso-Structures
Authors: Li Yongqiang , Chen Yong , Zhou Chi
Published: July 2010

Recent advances in sold freeform fabrication (SFF) present tremendous design freedom for a product design with complex geometries. In this paper, we consider the problem of using rigid materials to design flexible skin of a product component for SFF. A design strategy based on the combination of well-defined meso-structures is presented to achieve desired heterogeneous material properties, and consequently desired flexibility in target directions and positions. We present our computational framework to automate the design optimization process. Due to the dramatically increased design space, a brute force or traditional design optimization method such as the genetic algorithm (GA) and particle swam optimization (PSO) is not efficient. We present a design method based on the idea of analyzing the flexibility of each link for given meso-structures. Two experimental examples are presented to demonstrate its usage in generating the maximum/minimum and target displacements. We also present its comparison with the GA and PSO methods.
Dynamic Analysis of Ball Bearings Due to Clearance Effect
Authors: Upadhyay S. H. , Jain S. C. , Harsha S. P.
Published: July 2010

In this paper, the nonlinear dynamic behavior of ball bearings due to radial internal clearance and rotor speed has been analyzed. The approach presented in this paper accounts for the contact between rolling elements and inner/outer races. The equations of motion of a ball bearing are formulated in generalized coordinates, using Lagrange’s equation considering the vibration characteristics of the individual constitute such as inner race, outer race, rolling elements. The effects of speed of rotor in which rolling element bearings shows periodic, quasi-periodic and chaotic behavior are analyzed. The results also show the intermittent chaotic behavior in the dynamic response is seen to be strongly dependent on the speed of the rotor. The results are obtained in the form of frequency responses. The validity of the proposed model verified by comparison of frequency components of the system response with those obtained from experiments. The peak-to-peak frequency response of the system for each speed is obtained. The current study provides a powerful tool design and health monitoring of machine systems.
Remote Lab Infrastructure for Distance Learning Courses at the Undergraduate Level in Embedded Systems Design
Authors: Balog Peter , Horauer Martin , Ro¨ssler Peter
Published: July 2010

Lectures and labs with hands-on trainings and project based aspects are of high relevance for courses dedicated to embedded systems design when the transfer of practical skills is a major objective. Therefore, small classes, good support and frequent access to target platforms over a long period of time are beneficial. Providing access to the latter, however, can become a hassle for the organizers, especially when multiple courses are to be held in parallel or when they are organized as asynchronous distance learning courses. The problem is even aggravated when the platforms should be kept at the fore-front of the state-of-the-art. For this purpose we present in this paper concepts and implementation guidelines of a remote lab infrastructure that addresses these issues. In particular, the presented approach keeps the efforts to migrate to new embedded targets simple, enables nearly 24/7 times of access, ideally complements on-site trainings, and keeps the required costs low.
Dynamic Analysis of Structures With Nonlinear Bolted Joints by Using an Adaptive Harmonic Balance Method
Authors: Jaumouille´ Vincent , Sinou Jean-Jacques
Published: July 2010

Aeronautical structures are commonly assembled with bolted joints in which friction phenomena provide damping on the dynamic behaviour. Some models, mostly non linear, have consequently been developed and the harmonic balance method (HBM) is adapted to compute non linear response functions in the frequency domain. The basic idea is to develop the response as a Fourier series and to solve equations linking Fourier coefficients. One specific HBM feature is that response accuracy improves as the number of harmonics increases, at the expense of larger computational time. Thus the aim of this study is to develop an adaptive HBM which appreciates numerically the contribution of each harmonic on the dynamic response. For a given precision, the number of retained harmonics is adapted by an algorithm which integrates a numerical criterion based on an approximate strain energy. The application case is an asymmetrical two cantilever beam system linked by a bolted joint represented by a nonlinear LuGre model. Condensation and continuation methods are used to accelerate calculation. Adaptive HBM shows that, for a given value of the criterion, the number of harmonics may increase on resonances indicating that non linear effects are predominant.
Analysis of Vibro-Impact Dynamical System Using Piecewise Linear Vector Fields
Authors: Nakai Mikio
Published: July 2010

An analysis of the dynamic responses has been developed for all piecewise linear single-degree-of-freedom systems with boundaries for only displacement by applying analyses based on piecewise linear vector fields. Furthermore, a generalized solution methodology has been proposed for piecewise linear systems with boundaries for both displacement and time such as the system with parameters which give rise to separations due to clearances or backlash and for rotating machinery system with boundaries for both displacement and velocity. In this paper, this methodology was developed for analyzing dynamic responses of two vibro-impact systems: one with stops at both sides and another with a stop only at one side. In matrix representation for these systems, state variables can explicitly be expressed at each region as a function of the time when an orbit hits the stop. The time can be determined by the Brent method, and periodic solutions can then be obtained. Analytical solutions are validated on vibro-impact systems by using conventional method.
Vibration Damping in Bolted Friction Beam-Columns
Authors: Bournine Hadjila , Wagg David J. , Neild Simon
Published: July 2010

In this paper we consider dynamic friction within a bolted structure deliberately used to improve damping properties of engineering structures. The model considered for this paper consists of two steel beam-columns bolted together allowing dynamic friction to occur at the interface. The theoretical analysis presented here, include two physical approaches. The first approach is based on the optimization of the bolt tension to dissipate the maximum vibration energy by the structure. As a result of this analysis we develop analytical expressions for the energy dissipated by friction damping and optimal bolt tension for maximum energy dissipation. The second part of the analysis deals with the effect of friction on the mechanical properties of the structure. In this analysis, we define analytical expressions for the vibration modes before and after slip occurs. We also defined the stress profile across the column cross-section. The theoretical analysis was validated by a set of experimental results.
Biometric Monitoring of Footstep and Heart Rate Using Wireless Inertial Sensors
Authors: Ros Montserrat , D’Souza Matthew , Wallace Matthew
Published: July 2010

Inertial sensors are widely used for a variety of biomedical applications, such as human activity monitoring. We present a wireless biomedical monitoring network used for measuring footstep parameters and the heart rate of a person. The wireless biomedical monitoring network uses inertial sensors to record and monitor heart rate and consists of multiple monitoring nodes placed on a person, that communicate with a base node. The monitoring nodes placed on a person’s ankle measure the acceleration generated during a footstep. By analysing this data, we are able to determine the average footstep length and walking velocity to be 80cm and the average walking speed to be 1m/s which corresponds to results found by existing studies. A monitoring node placed on the right Carotid artery in the neck region was able to measure the vibrations generated by the movement of blood. Analysis of the acceleration signals generated by the pressure pulse showed that it was possible to determine the heart rate of the person. We found that a sitting person had a heart rate of 75 BPM, which was confirmed by an electrocardiogram device. Further areas of investigation involve improving the sensitivity of the monitoring node’s accelerometer sensor by using a diaphragm and also to measure a person’s blood pressure using inertial sensing.
Multiple Synchronous States in Static Delay-Free Oscillator Networks
Authors: Orsatti Fernando M. , Piqueira Jos Roberto C.
Published: July 2010

Oscillatory neuro computers may be implemented by networks of oscillators. In these computers, multiple synchronous states of the network are associated with different patterns to be memorized. In this way, memorized pattern are retrieved as different synchronous states are achieved depending on the initial phase differences between nodes. Using a general network model, whit sawtooth coupling characteristic between nodes, we give upper bounds for the number of possible synchronous states for the network and we show, numerically, that even in a static three-node network, multiple synchronous states may exist for the network, and that the achieved state depends only on the initial conditions of the network.
Kinematic Optimization of a Redundantly Actuated Parallel Mechanism for Maximizing Active Stiffness and Workspace Using Taguchi Method
Authors: Shin Hyunpyo , Lee SungCheul , In Woosung , Jeong Jay I. , Kim Jongwon
Published: July 2010

We present an optimization procedure that uses the Taguchi method to optimize the mean stiffness and workspace of a redundantly actuated parallel mechanism. The kinematic parameters of a planar 2-DOF parallel manipulator are optimized to maximize the manipulator’s workspace and mean stiffness at the same time. Kinematic analysis is performed to obtain a constraint Jacobian and forward Jacobian. And stiffness analysis of the redundantly actuated parallel manipulator is performed based on the virtual work theorem. The Taguchi method is applied to separate the more influential and controllable variables from the less influential ones in the optimization procedure. In the first stage of optimization, the number of experimental variables is reduced by response analysis. And after the response analysis, quasi-optimal kinematic parameter group is obtained in the second stage of optimization. The optimization procedure was used to investigate the optimal kinematic parameter groups and the relationship between the length and the stiffness of the link.
Architecture of Sensor Network System for Promoting Condition-Based Maintenance and Reuse
Authors: Tateno Toshitake , Kondoh Shinsuke
Published: July 2010

Considering the environmental load of material and energy consumption, many approaches to product design and manufacture have been discussed from an ecological viewpoint. In this paper, we propose the architecture of a sensor network system that promotes condition-based maintenance and reuse in order to reduce the environmental load in product manufacture and use. The system architecture stands on an agent-based sensor network and a modular reusable design. In this system, sensor data are used not only for condition-based maintenance but also for reuse management since they enable the estimation of product conditions that are indices for deciding a lifecycle option and a reuse plan. As a simple realization model of the proposed architecture, a motor-assisted bicycle CBM and reuse support system is developed by using wireless small sensor network and network agent systems. The system monitors product conditions and searches the next owner of each module for promoting reuse and avoiding product waste as much as possible. Case studies show some practical use and merits of this architecture.
Locomotion of a Submerged Cosserat Beam
Authors: Leyendecker Sigrid , Kanso Eva
Published: July 2010

We study the dynamics and locomotion of a neutrally-buoyant deformable body that can undergo finite shape deformations and is immersed in a perfect and incompressible fluid. We model the body as a constrained Cosserat beam, more precisely, a Kirchhoff beam, and we derive the equations governing its motion in potential flow where the ambient fluid is accounted for using the added mass effect. We show that the submerged beam can undergo net locomotion due to applied torsional loading on its centerline.
Comparing Generalized Order PID Controllers for Networked Control Systems With Random Delays and Data Dropouts
Authors: Tejado Ine´s , Vinagre Blas M. , Chen YangQuan
Published: July 2010

The performance of a Networked Control System (NCS) can be affected directly and indirectly by transmission time delays and data losses in the communications network. In this paper, we propose different control strategies, traditional and fractional order PID controllers, to control remotely an experimental platform, called Smart Wheel, at the Center for Self-Organizing and Intelligent Systems (CSOIS), Utah State University, and analyze their effectiveness by means of the jitter margin in simulation. A simulation model of a communications network for different nature of transmission delays, based on MATLAB/Simulink, is presented and used for simulations.
Issues of Today’s Product Lifecycle Management (PLM): Challenges and Upcoming Trends to Support the Early Phases of the Product Development Process
Authors: Maletz Michael , Eigner Martin , Zamazal Klaus
Published: July 2010

The requirements for the optimization of the Product Development Process (PDP) in manufacturing companies have grown enormously. There are many key concerns to which a modern PDP must respond. Lean production, structures oriented towards the business process, shorter product cycles and delivery times, as well as decreasing vertical range of manufacture in conjunction with decentralized customer/supplier cooperation, cost pressure, and quality management are only some examples. It is evident that in the early phase of the product development process 70% of the product costs are specified. This fact led to the beginning to already use improved methods, processes and IT solutions even in the early concept phase to have the highest influence on development projects. Typical topics for the optimization of the development processes and later realization in Product Lifecycle Management (PLM) solutions are Complexity Management, integration from Requirement Management to Product Structure, Multi-Domain (Mechatronic) Functional Product Description and Collaboration. This paper discusses above mentioned challenges to outline the originating problems arising from these challenges. Based on that, approaches to overcome these issues are outlined. Upcoming realization trends of PLM such as process oriented PLM implementation and Acceptance Management (to center human factors) complete this paper.