bluuebunny/crossref_metadata_2025 huggingface dataset:
Sums of the Zeros of the Single Parameter Mittag-Leffler Function With the Parameter Equal to One-Half
Authors: Hanneken John W. , Narahari Achar B. N. , Vaught David M. , Andrews James M. , Carr Avery T.
Published: July 2010

The sums of the powers of the reciprocals of the non-trivial (non-zero) zeros of the single parameter Mittag-Leffler function with alpha equal to one-half have been investigated. Analytical results for these sums were compared to the results from numerically summing over a billion zeros. Sums for integer powers from 3 to 10 agreed with the predictions of the analytical results but not for powers 1 and 2. The sum of the reciprocals of the zeros diverged in contrast to the analytical result and the sum of the squares of the zeros converged to a different result than predicted. This illustrates that the analytical results for polynomials cannot in general be applied to the infinite series representation of the Mittag-Leffler functions.
Virtual vs. Physical: An Experimental Study to Improve Shape Perception
Authors: Mengoni Maura , Peruzzini Margherita , Germani Michele
Published: July 2010

Product designers, in order to create value, need to enrich their understanding of users products experience and the whole set of activities involved in it. Human-Centered Design (HCD) regards with the development of design principles to support product features definition answering to physical, psychological, social and cultural needs of human beings. Usability tests generally allow the investigation of product performance in terms of efficiency, effectiveness and users satisfaction in order to reduce the gap between the perceived and the designed product quality. Main problems concern with the assessment of emotional usability, the identification of product features stimulating affective response and their translation into design requirements. Usability tests are generally carried out only at the end of the design cycle once a final physical prototype has been realized. As a consequence design modifications increase time to market. Instead of traditional CAD-based systems (Computer Aided Design), Virtual Reality (VR) represents new Human-Computer Interfaces that can support the multimodal interaction with virtual prototypes to perform usability tests at the early design stages. The present paper explores the potentialities of VR to support usability testing mainly focusing on emotional aspects. A protocol study is defined to analyze how sample users perceive product attributes determining affordances and synaesthesia qualities. The protocol adopts qualitative and quantitative metrics to objectify users emotional response while interacting with products. It allows correlating product attributes, in terms of materials, shape and aesthetic features combination, with user behavior and product performance. It has been applied in the field of household appliances. Two different experimental set-ups, physical and virtual, have been used to validate the protocol and highlight the main VR technologies drawbacks.
F.E.M. Design Method of Metallic and Composite Smart Structures With Piezoelectric Actuators
Authors: Pommier-Budinger Vale´rie , Budinger Marc , Martinez Javier Romero , Galan Galan Rafael
Published: July 2010

This article describes a design method to size smart structures with piezoelectric ceramics. The method makes it possible to determine the amplitudes of vibrations that may be generated by piezoelectric ceramics bonded on a metallic or composite structure. One of the possible applications of the method is the preliminary design of smart structures for active vibration control. This case is particularly treated in this article. The method is based on a reduced model that can be established using a multiphysics FEM software. This model can also be used to compute the control law for vibrations attenuation.
Global Bifurcation and Multipulse Type Chaotic Dynamics in the Nonlinear Nonplanar Oscillations of a Cantilever Beam
Authors: Zhang Wei , Li Shuangbao , Yao Minghui
Published: July 2010

The global bifurcation and multipulse type chaotic dynamics for the nonlinear nonplanar oscillations of a cantilever beam are studied using the extended Melnikov method. The cantilever beam studied is subjected to a harmonic axial excitation and transverse excitations at the free end. After the governing nonlinear equations of nonplanar motion with parametric and external excitations are given, the Galerkin procedure is applied to the partial differential governing equation to obtain a two-degree-of-freedom nonlinear system with parametric and forcing excitations. The resonant case considered here is 1:1 internal resonance, principal parametric resonance-1/2 subharmonic resonance. By using the method of multiple scales the averaged equations are obtained. After transforming the averaged equation in a suitable form, the extended Melnikov method is employed to show the existence of chaotic dynamics by identifying Shilnikov-type multipulse orbits in the perturbed phase space. We are able to obtain the explicit restriction conditions on the damping, forcing, and the detuning parameters, under which multipulse-type chaotic dynamics is to be expected. Numerical simulations indicate that there exist different forms of the chaotic responses and jumping phenomena in the nonlinear nonplanar oscillations of the cantilever beam.
Random Loads Fatigue: The Simulation of Non-Linear Systems
Authors: Cianetti Filippo , Braccesi Claudio
Published: July 2010

In this paper the problem of the correct evaluation of the stress state of mechanical components of non linear systems in the frequency domain was analysed. This is one of the most important steps in the frequency domain evaluation of the fatigue behaviour of components under random loads. A new methodology to obtain an accurate representation in frequency domain of the non-linear behaviour of the system as well as of the stress state of the components both in terms of power spectral density (PSD) function and of frequency response function (FRF) was proposed and validated. This methodology fits well into a damage evaluation scenario that also involves the non Gaussianity of the process.
Targeted Energy Transfer With Several NES in Parallel: Theory and Experiments
Authors: Ture Savadkoohi Alireza , Pernot Stephane , Lamarque Claude Henri
Published: July 2010

The crucial point in the field of seismic engineering is to diminish the induced vibration energy as much as possible in a fast and almost irreversible manner. Recently the concept of Nonlinear Energy Sink (NES) has been developed such that the imposed energy to a linear single Degree of Freedom (DoF) substructure is transferred to one or series of strongly nonlinear light attachments; the mechanism is based on a 1:1 resonance capture. Nonlinear attachments can be designed to passively vibrate with any frequency; hence the system is efficient for both of transient and periodic excitations. Some drawbacks of these systems are as follows: they cannot kill the first peak of oscillation in the free time response that is linked to the energy activation of NES; moreover, the transformation of energy vanishes in time due to decrease of the strength of energy pumping. Using NES in series even cannot accelerate the phenomenon of energy pumping and some strange behavior due to the delay in the cooperation of NES in series is noticed. In this study, the transient dynamic behavior of multiple DoF systems with trees of parallel NES at each DoF is investigated, then experimental and numerical results of a four DoF structure with two parallel NES at the top floor are demonstrated and commented upon.
On the Monitoring and Diagnosis of Assembly Faults in Diesel Engine Cold Tests: A Case Study
Authors: Delvecchio Simone , D’Elia Gianluca , Mucchi Emiliano , Di Gregorio Raffaele
Published: July 2010

This work addresses the use of several signal processing tools as a means for the monitoring and the diagnosis of assembly faults in internal combustion (i.c) engines through the cold test technology. Firstly, an approach based on the use of symmetrized dot patterns for the visual characterization of vibration signatures is proposed. This method is applied in order to obtain reliable thresholds for the pass/fail decision after the cold test. Secondly, the fault identification is discussed on the basis of the cyclostationary modeling of the signals. First of all, first-order cyclostationarity is exploited through the analysis of the Time Synchronous Average (TSA). Subsequently, second-order cyclostationarity is developed by means of the mean instantaneous power, Wigner-Ville Distribution (WVD) and Wigner-Ville Spectrum (WVS). Finally, the Continuous Wavelet Transform (CWT) is presented and compared with the Wigner Ville Distribution. In order to show the effectiveness and the limitations of the above-mentioned techniques, tests were carried out for a number of different faults. In this paper the results relative to a specific fault are shown as example.
FEA Study of Belt Angle Effect to Cornering Stiffness and Ply Steer
Authors: Lu Min
Published: July 2010

Performance of vehicle turn and lane change can be evaluated by cornering stiffness. One of many factors affecting the cornering stiffness is belt angle. In 1998, Koishi et al [1] published the findings of cornering stiffness when belt angle is at 0 and 20 degrees, using a finite element code PAM-SHOCK. Results from two cases only are not enough completing the parametric study. With better hardware and software available today than before, the same tire model is re-visited, using new form of numerical procedure — a mixed Eulerian/Langrangian formulation called steady state transport analysis in ABAQUS. Cornering stiffness at the range of 0 to 40 degree belt angle with 5 degree increment is calculated. The results show that three distinct regions exist. At Region I, in which the belt angle ranges from 0–10 degrees, the cornering stiffness increases as the belt angle increases. The cornering stiffness maximizes out and remains flat at Region II, when belt angle is between 10 to 25 degrees. Cornering stiffness decreases as the belt angle increases in Region III, where the belt angle is larger than 25 degree. The existence of Region II may explain the fact that manufacturers prefer around 20 degree belt angle for their tire designs: maximum cornering stiffness and its insensitivity to the belt angle variation. The plot of the predicted ply steer in this study agrees reasonably well with a published experimental data.
Integrated Control of Active Suspension System and Active Front Steering System Using Hierarchical Control Method
Authors: Zhang Weihua , Chen Wuwei , Xiao Hansong , Zhu Hui
Published: July 2010

Integrated vehicle control has been an important research topic in the area of vehicle dynamics and control in recent years. The aim of integrated vehicle control is to improve the overall vehicle performance including handling, stability and comfort through creating synergies in the use of sensor information, hardware, and control strategies. This paper proposes a two-layer hierarchical control architecture for integrated control of active suspension system (ASS) and active front steering system (AFS). The upper layer controller is designed to coordinate the interactions between the ASS and the AFS. While in the lower layer, the two controllers including the ASS and the AFS, are developed independently to achieve their local control objectives. Simulation results show that the proposed hierarchical control system is able to improve both the ride comfort and the lateral stability compared to the non-integrated control approach.
Parallel Linear Equation Solvers and OpenMP in the Context of Multibody System Dynamics
Authors: Gonza´lez Francisco , Luaces Alberto , Dopico Daniel , Gonza´lez Manuel
Published: July 2010

Computational efficiency of numerical simulations is a key issue in multibody system (MBS) dynamics, and parallel computing is one of the most promising approaches to increase the computational efficiency of MBS dynamic simulations. The present work evaluates two non-intrusive parallelization techniques for multibody system dynamics: parallel sparse linear equation solvers and OpenMP. Both techniques can be applied to existing simulation software with minimal changes in the code structure; this is a major advantage over MPI (Message Passing Interface), the de facto standard parallelization method in multibody dynamics. Both techniques have been applied to parallelize a starting sequential implementation of a global index-3 augmented Lagrangian formulation combined with the trapezoidal rule as numerical integrator, in order to solve the forward dynamics of a variable number of loops four-bar mechanism. This starting implementation represented a highly optimized code, where the overhead of parallelization would represent a considerable part of the total amount of elapsed time in calculations. Several multi-threaded solvers have been added to the original software. In addition, parallelizable regions of the code have been detected and multi-threaded via OpenMP directives. Numerical experiments have been performed to measure the efficiency of the parallelized code as a function of problem size and matrix filling ratio. Results show that the best parallel solver (Pardiso) performs better than the best sequential solver (CHOLMOD) for multibody problems of large and medium sizes leading to matrix fillings above 10 non-zeros per variable. OpenMP also proved to be advantageous even for problems of small sizes, in despite of the small percentage of parallelizable workload with respect to the total burden of the execution of the code. Both techniques delivered speedups above 70% of the maximum theoretical values for a wide range of multibody problems.
Generalized Mass Metric and Recursive Momentum Formulation for Dynamics of Multibody Systems
Authors: Zhao Qiang , Wu HongTao , Zhou Minghu
Published: July 2010

Generalized mass metric in Riemannian manifold plays a central role in dynamics and control of multibody system (MBS). In this work, two profitable aspects of multibody system dynamics studies, generalized mass metric in Riemannian geometry and recursive momentum formulation, are described. Firstly, we will derive an Adjoint-based expression of Riemannian metric and operator factorization of generalized mass tensor from a general-topology rigid MBS which comprises of a special Euclidian group SE(3) set. The specific expression can help to clearly understand what reasons lead to these components (Riemannian metric) of the generalized mass tensor and how they measure the curves of generalized velocity space. Meanwhile, the power algorithm of MBS is presented based on the Adjoint map of generalized velocity and generalized force. Next, from the generalized momentum definition depending on such Riemannian mass metric, recursive momentum equations of MBS dynamics are developed for progressively more complex systems: open-chains, topological trees, and closed-loop systems. In terms of the relation principle of impulse and momentum, a new method is proposed for describing conservative MBS form a given initial orientation and location to desired final ones without needing to solve motion process.
Nonlinear Vibration of a Thin Laminate Due to the Stochastic Thermal Diffusion
Authors: He Xiaoling
Published: July 2010

We study the thermally induced nonlinear vibration of a laminate associated with the stochastic thermal diffusion. The stochastic diffusion process occurs in the conductive laminate with white noise. We consider the thermal field with temperature variation both in-plane and transverse to the plane of lamina. Our interest is to examine the stochastic resonance behavior due to different noise sources and noise strength. The equation of motion for the laminate is based on the decoupled modal form Duffing equation developed in our earlier study for the laminate in a simply supported boundary condition. The thermal fluctuation is of the additive and multiplicative Gaussian noise, respectively, with or without correction between the two noises. The computation demonstrates the stochastic resonance phenomena due to noise induced escape phenomena. The results provide a realistic prediction for the thermal vibration behavior of a laminate when the stochastic thermal process is present.
User-Oriented Simulation Models of Piezo-Bar Actuators: Part I—Linear Approach
Authors: Boukari Abdou-Fadel , Moraru George , Carmona Jean-Claude , Malburet Francois
Published: July 2010

The emergence of electro-active materials such as piezoelectric ones allows recently to think back actuating and sensing functions thanks to new principles of electromechanically conversion of energy. The interesting properties of these materials lead up to considering the generalization of their use in various applications such as automobile, aeronautics or machining. However this enthusiasm quickly goes away when a common engineer has to be confronted to the quasi absence of ready-to-be-used models of devices made of these materials [14]. This comes from the fact that piezoelectricity still remains the mind of the experts of materials. This is why in this paper we aim to formalize and wittingly simplify existing approaches of modeling piezo-actuators. Our goal is to make available to all a method of constituting at least a basic library of piezo-actuators models. This set of models is intended and designed to be completed by more deepen models integrating several aspects neglected in basic models.
On the Stereoscopic Composition of Wide Baseline Stereo Pairs
Authors: Wang Chensheng , Wang Xiaochun , Vergeest Joris S. M. , Wiegers Tjamme
Published: July 2010

Wide baseline cameras are broadly utilized in binocular vision systems, delivering depth information and stereoscopic images of the scene that are crucial both in virtual reality and in computer vision applications. However, due to the large distance between the two cameras, the stereoscopic composition of stereo pairs with wide baseline is hardly to fit the human eye parallax. In this paper, techniques and algorithms for the stereoscopic composition of wide baseline stereo pairs in binocular vision will be investigated. By incorporating the human parallax limitation, a novel algorithm being capable of adjusting the wide baseline stereo pairs to compose a high quality stereoscopic image will be formulated. The main idea behind the proposed algorithm is, by simulating the eyeball rotation, to shift the wide baseline stereo pairs closer to each other to fit the human parallax limit. This makes it possible for the wide baseline stereo pairs to be composed into a recognizable stereoscopic image in terms of human parallax with a minor cost of variation in the depth cue. In addition, the depth variations before and after the shifting of the stereo pairs are evaluated by conducting an error estimation. Examples are provided for the evaluation of the proposed algorithm. And the quality of the composed stereoscopic images proves that the proposed algorithm is both valid and effective.
Numerical Investigations of Mechanical Responses, Friction and the Formation of Debris of UHMWPE in Total Joint Replacements
Authors: Ren Xuchun , Tangpong X. W. , Zhong W. H.
Published: July 2010

Finite element models are developed using ABAQUS and LS-DYNA to investigate the mechanical responses, friction and formation of debris in the contact of Ultra High Molecular Weight Polyethylene (UHMWPE) asperities with metal. The objective is to gain an understanding of wear particle generation mechanism in total joint replacements. Several types of materials including UHMWPE, High Density Polyethylene (HDPE) and Carbon Nanotube-reinforced High Density Polyethylene (CNT-HDPE) with different volume fractions of CNTs are selected to investigate the effect of material properties on friction coefficient. The plastic strain contour and stress contour are obtained in micrometer scale. To assess the influence of the material properties to friction coefficient, an energy-based model is adopted to calculate the plastic dissipation. Time averages of the friction coefficient are taken for comparison purposes. The finite element analysis and the energy-based model are capable of predicting the trend of the average friction coefficient changing with the material properties. A plastic strain damage model is used to investigate the formation of debris during the contact of an UHMWPE cup and a CoCr alloy femoral head in total hip joint replacement. The debris size predicted by the finite element model is consistent with some experimental results in the literature.
Dynamic Response Analysis for Non-Smooth Gear Rattling System
Authors: Xu Kai , Deng Xiaozhong , Yang Jianjun , Liu Geng
Published: July 2010

For non-smooth gear rattling system, a general dynamic model with backlash consisting of two wheels with a sinusoidal driving is considered in this paper. Selecting the tooth face as the Poincare´ section, the Poincare´ map is constructed, and a calculation method of Lyapunov exponents presented by using the local map method to avoid calculating the Jacobian at the impact points. An example is given to validate the above calculation method. The results show that with increase in forcing amplitude, the motion state of the gear rattling system will change from single-sided tooth impact to double-sided tooth impact. The corresponding phase plane plots are shown. The spectrums of the largest Lyapunov exponents are calculated in a large range of parameters, and the results compared with the bifurcation diagrams obtained by means of local map method in the corresponding parameter range.
Effects of Rolling Friction on Ball Positioning for an Automatic Ball Balancer
Authors: Chan T. C. , Sung C. K. , Chao Paul C. P. , Hung Y. M.
Published: July 2010

This paper presents a theoretical and experimental study on the effects of rolling friction between balls and the racer on ball positioning for an automatic ball balancer (ABB). The performance of an ABB, which is characterized by residual vibration of the rotor, relies heavily on balls’ positions. However, the magnitude of rolling friction determines the ball position of the balancing system, which in turn affects the performance of the ABB. In this study, a set of ball balancers are fabricated including ceramic balls and the associated PTFE and ceramic ball races for the purpose of investigating the validity of the mathematical model of the rolling friction. The driving-force equation associated with the dynamic equations of motion of the balls is developed to determine the ball positions as well as the performance of the balancing system. Two sets of experimental apparatus are constructed. One is aimed to verify the mathematical model of the rolling friction of the ball balancer. The other applies an optical-disc drive system together with a high-speed camera to record the ball positions and verify the results obtained from computer simulation.
The Revelation of Propagating Ultrasonic Guided Waves Through Simulation When They Encountered Defects in a Pipe
Authors: Tang S. , Tse P. , Wang X.
Published: July 2010

In Hong Kong, there are many gas and water pipelines buried under buildings and roads. A rupture of the water or gas pipeline may cause serious interruption to traffic and even human casualties. Therefore, a single-point based and easy-to-install pipeline inspection system is essential to Hong Kong daily living and crucial to public safety. One of the effective and convenient inspection methods for underground pipeline inspection is the ultrasonic-based guided waves. The success in pipe inspection relies on the emission of proper mode of guided waves to a particular type of pipe. To derive the necessary parameters in helping the selection of optimal mode of waves, one can use simulation or real experiments. The cost and difficulty in conducting live experiments on roads are too high, especially in a dense living area like Hong Kong. Hence, simulation is preferred to minimize the frequency and number of experiments necessary to be conducted. A finite element method (FEM) tool, called ANSYS, was selected to build the required dynamical models. However, several obstacles must be solved prior to the development of 3D models for pipes suffering from various defects. These obstacles include the complexity in simulating high frequency guided waves when they are propagating inside a pipeline, the requirements of huge memory space and intensive computational resources. In this paper, we present detailed descriptions on solving these obstacles. The methods to determine the optimal element size and time step are also reported so that the best trade-off can be achieved in terms of efficiency and computational intensity. To verify the accuracy in simulations, selected experiments were conducted for verification purpose. The results show good agreement between the results of simulations and experiments.
A Novel Two DOF Control for Train-Like Guidance of Multiple Articulated Vehicles
Authors: Wagner Sebastian , Zipser Stephan , Bartholomaeus Ralf , Baeker Bernard
Published: July 2010

This paper presents a novel two DOF control for train-like guidance of general multiple articulated vehicles with all wheel steering. The model based control scheme consists of a feed-forward and a feedback part designed separately. Within the nonlinear feedforward part the steering angles are calculated that theoretically cause every single axle to follow a desired path exactly. Thus in the nonlinear feedback part only model uncertainties and disturbances have to be compensated. Simulations as well as road tests show that the designed control system allows train-like vehicle guidance while it is robust against varying road conditions, payload as well as velocity.
Compensating Learning Control for Free-Floating Space Robot System With Dual-Arms Using Genetic Algorithm in Joints Space
Authors: Tang Xiaoteng , Chen Li
Published: July 2010

In this paper, the kinematics and dynamics of free-floating space robot system with dual-arms are analyzed. The closed-loop dynamic error equation considering uncertainties for the space robot is derived using the PD type computed torque method. A new learning control method using real coded genetic algorithm is presented to control the system and its controller structure is designed. A compensating learning control item is added to the error equation to approach the uncertainties by evolutionary learning. Then, the computed torque method and the GA learning control are combined to realize the perfect trajectory tracking. Simulation results show the efficiency of the control method.
Active Self-Excited Vibration Elimination of Rotating Machine With an Electromagnetic Exciter
Authors: Fan Chen-Chao , Pan Min-Chun
Published: July 2010

Journal bearings are commonly used in large rotary machineries because they have excellent mechanical and geometric properties as well as large load-carrying capacities. Nevertheless, the oil whirl and oil whip instabilities limit their applications due to their insufficient stiffness at high running speeds. This paper presents a method to increase the stiffness of a rotating machine using an electromagnetic exciter (EE), which can raise the threshold of instability of the rotating machine and eliminate fluid-induced instability. The EE is a controllable auxiliary device that can provide additional stiffness to the bearings to increase the operating ranges of a rotating machine, while the journal bearings act as load-carrying devices. Together, the EE complements the JB to stiffen the rotor system and raise the threshold of instability. A simple control scheme is used to calculate the amount of supplemental stiffness supplied by the EE. The experimental results demonstrate that the oil whirl and oil whip instabilities of the rotating machine can be eliminated effectively, even at higher running speeds. The advantage of the EE is to offer a faster, more stable method to eliminate fluid-induced instability.
UAV Autopilot Design for the AUVSI, UAS International Competition
Authors: Mahmood Muhammad M. , Chowdhury Md S. , Ihsan Rizwan , Yousaf Umar M. , Afifi Mohamed W. , Chuwdhury Imtiaz M.
Published: July 2010

This paper provides an overview of the first participation of the design developed by the undergraduate students of American University of Sharjah to meet the requirements laid forth in the 2008 Association for Unmanned Vehicle Systems International (AUVSI) Student UAS competition. The overall objective of the competition is to fly autonomously over a GPS waypoint defined route and also to identify and locate ground based targets within a confined area. To meet the objectives an unmanned aircraft is equipped with autonomous functionality and aerial imaging system. A ground station and supportive software to keep track of the aircraft routine and log the raw data gained from the flight is also designed. Achieving complete success depends upon mission elements which include autonomous take-off and landing, autonomous control and waypoint navigation. The onboard equipment used was a flight control computer network, IMU, GPS, an air data system and a camera. Additionally, safety features such as manual override was also installed. Presented in this report are aircraft design and testing, the processes involved in accomplishing the goal, and the results and achievements.
Parameter Identification of a Cantilever Beam Immersed in Viscous Fluids With Potential Applications to the Probe Calibration of Atomic Force Microscopes
Authors: Li Wenlung , Tseng S. P.
Published: July 2010

The main objective of the report is to present a new identification method has been derived for single-degree, base-excited systems. The system is actually to mimic a probe of cantilever type of AFMs. In fact, the idea of the present report was initiated by needs for in situ spring constant calibration for such probe systems. Calibration processes can be treated as parameter identification for the stiffness of the probe before it is used. However, sine a real probe is too small to be seen by bare eyes and too costly to verify, a cantilever beam was adopted to replace it during the study. The present method starts with giving a chirp excitation to the target system, and to lock the damped natural frequency. Once the damped natural frequency is obtained, it is possible to locate the frequency at which the phase lag is equal to π/2. From which, the excitation frequency is then purposely changed to that frequency and the corresponding steady-state responses are measured. In the meantime, the system dissipative energy or power may also need to be stored. In fact, the present identification formulation is to express the spring constant of the target systems in terms of two measurable parameters: the phase angle and the system damping. The former can be computed from the damped natural frequency while the latter can be identified along with measuring the input power. The novel formulation is then numerically simulated using the Simulink toolbox of MATLAB. The simulation results clearly showed the current identification method can work with good accuracy. Following the numerical simulation, experimental measurements were also carried out by a cantilever beam that its free end was immersed to viscid fluids. The fluids of different viscosity were used to mimic the environments of a probe in use. The experimental results again substantiated the correctness of the present method. Thus it is accordingly concluded that the new recognition algorithm can be applied with confidence.
Damage Identification Through Spectral Element Model Updating
Authors: Arafa Mustafa H. , Nassef Ashraf O.
Published: July 2010

The use of vibration-based damage identification techniques has received considerable attention in recent years. These techniques rely on changes in some structural dynamic characteristics in order to establish a damage indicator. While various damage indicators have been reported in the literature, those relying only on changes in the natural frequencies are appealing in many aspects. Nevertheless, the use of natural frequencies in damage identification has been faced with several difficulties, such as insensitivity and uniqueness concerns. In an attempt to overcome these obstacles, this paper addresses the development of a damage identification scheme based on changes in the natural frequencies of beam structures through a numerical model formulated by the Spectral Element Method (SEM) in conjunction with an optimization algorithm in a model updating approach to predict the location and extent of damage. The use of the SEM significantly reduces the number of design variables, which makes the search algorithm in the inverse problem faster and more efficient. Damage is modeled as a localized reduction in the beam thickness. Three spectral elements are employed to model an elastic beam with a defect and three variables are realized to model the location, size and severity of damage. A stochastic genetic algorithm was developed to facilitate the search for damage based on a set of measured natural frequencies. The use of the proposed formulation is supported experimentally on a set of free-free beams provided with various damage scenarios, and is shown to be a viable tool in damage identification.
Design and Preliminary Validation of a Rapid Automated Biodosimetry Tool for High Throughput Radiological Triage
Authors: Chen Youhua , Zhang Jian , Wang Hongliang , Garty Guy , Xu Yanping , Lyulko Oleksandra V. , Turner Helen C. , Randers-Pehrson Gerhard , Simaan Nabil , Yao Y. Lawrence , Brenner D. J.
Published: July 2010

This paper presents design, hardware, software, and parameter optimization for a novel robotic automation system. RABiT is a Rapid Automated Biodosimetry Tool for high throughput radiological triage. The design considerations guiding the hardware and software architecture are presented with focus on methods of communication, ease of implementation, and need for real-time control versus soft time control cycles. The design and parameter determination for a non-contact PVC capillary laser cutting system is presented. A novel approach for lymphocyte concentration estimation based on computer vision is reported. Experimental evaluations of the system components validate the success of our prototype system in achieving a throughput of 6,000 samples in a period of 18 hours.
Microraptor: A Low-Cost Autonomous Quadrotor System
Authors: Rawashdeh Osamah A. , Yang Hong Chul , AbouSleiman Rami D. , Sababha Belal H.
Published: July 2010

This paper describes Microraptor, a complete low-cost autonomous quadrotor system designed for surveillance and reconnaissance applications. The Microraptor ground station is custom-made and features a graphical user interface that presents and allows the manipulation of various flight parameters. The aerial vehicle is a 4-rotor vertical takeoff and landing (VTOL) vehicle that features the advantages of traditional helicopters with significant reduction in mechanical complexity. The vehicle frame is a handmade magnesium and carbon fiber structure. The onboard avionics system is a custom dual processor design capable of autonomous path navigation and data exchange with the ground station. The vehicle is outfitted with a video and still-photo system that provides real-time images to the system operator through the GUI. The system is being developed at Oakland University by a team of multidisciplinary undergraduate and graduate engineering students. Microraptor placed 5th at the 2008 Association for Unmanned Vehicle Systems International (AUVSI) Unmanned Aerial Systems (UAS) Competition and is set to compete again in June of 2009.
Developing a Lean Value Model for Product Development
Authors: Yadav Salik , Allada Venkat
Published: July 2010

This paper presents a value quantification model for multi-stage product development using lean principles. The proposed value model considers four main stages of product development (PD) including conceptual development, systems design, detailed design and prototyping. The model determines an optimal solution for each of the design variables to maximize the value at each of the PD stages. The value at each of the PD stages is formulated as a function of the six factors: (a) importance of customer requirements (b) cost of customer’s ownership, (c) parts/service availability, (d) weighted average cost of capital, (e) information evolution and (f) risk reduction. Factors (a)-(d) have been adequately addressed in the literature. This study focuses on information evolution and risk reduction. These two factors are defined by a set of value attributes including performance, risk, schedule, cost, form, fit, function and timeliness. An example of Detonator Disposal (DD) robot family is used to explain the working of the proposed model.
Team OSAM-UAV’s Design for the 2008 AUVSI Student UAS Competition
Authors: Hall Christopher J. , Morgan Daniel , Jensen Austin , Chao Haiyang , Coopmans Calvin , Humpherys Mitchel , Chen YangQuan
Published: July 2010

This paper, was originally prepared for and presented at the 2008 AUVSI Student UAS Competition, it provides the OSAM-UAV (Open-Source Autonomous Multiple Unmanned Aerial Vehicle) team’s design of an unmanned aircraft system for remote target recognition missions. Our OSAM-UAVs are designed to be small in size with strong airframes, and low-cost using open-source in both autopilot hardware and flight control software. A robust EPP-based delta wing airframe is used to prevent damage to the airframe during landing or even crashes. Autonomous navigation is achieved using an open-source Paparazzi autopilot, which gives special attention to safety during operation. Our system has been further enhanced by using the Xbow MNAV Inertial Measurement Unit (IMU) in place of the Paparazzi’s standard infrared (IR) sensors, for better georeferencing. An array of light-weight video cameras have been embedded in the airframe, which stream video to the ground control station through wireless transmitters in real-time. The ground control system includes a computer vision system, which processes and geo-references images in real-time for target recognition. Experimental results show the successful autonomous waypoint navigation and real-time image processing.
Towards Solving the Missing Marker Problem in Realtime Motion Capture
Authors: Piazza Tommaso , Lundstro¨m Johan , Hugestrand Alexander , Kunz Andreas , Fjeld Morten
Published: July 2010

A common problem in optical motion capture is the so-called missing marker problem. The occlusion of markers can lead to significant loss of tracking accuracy unless continuous data flow is guaranteed by computationally demanding interpolation or extrapolation schemes. Since interpolation algorithms require data sampled before and after an occlusion, they cannot be used for real-time applications. Extrapolation algorithms only require data sampled before an occlusion. Other algorithms require statistical data and are designed for post-processing. In order to bridge sampling gaps caused by occluded markers and hence to improve 3D real-time motion capture, we suggest a real-time extrapolation algorithm. The realization of this prediction algorithm does not need statistical data or rely on an underlying cinematic human model with pre-defined marker distances. Under the assumption that natural motion can be linear, circular, or a linear combination of both, a prediction method is suggested and realized. The paper presents linear and circular movement measurements for use when a marker is briefly lost. The suggested extrapolation method seems to behave well for a reasonable number of frames, not exceeding 200 milliseconds.
Solutions of a Fractional Dirac Equation
Authors: Muslih Sami I. , Agrawal Om P. , Baleanu Dumitru
Published: July 2010

This is a short version of a paper on the solution of a Fractional Dirac Equation (FDE). In this paper, we present two different techniques to obtain a new FDE. The first technique is based on a Fractional Variational Principle (FVP). For completeness and ease in the discussion to follow, we briefly describe the fractional Euler-Lagrange equations, and define a new Lagrangian Density Function to obtain the desired FDE. The second technique we define a new Fractional Klein-Gordon Equation (FKGE) in terms of fractional operators and fractional momenta, and use this equation to obtain the FDE. Our FDE could be of any order. We present eigensolutions for the FDE which are very similar to those for the regular Dirac equation. We give only a brief exposition of the topics here. An extended version of this work will be presented elsewhere.
An Improved Method for Predicting Minor-Axis Shear Stresses in Rectangular Shafts Under Torsion Using Optimization Polynomials
Authors: Shoup Terry E.
Published: July 2010

This paper presents four new approximation formulas for predicting the shear stress in rectangular members subjected to torque loading. The results are developed using a hybrid optimization method applied to a polynomial merit function to predict the maximum shear stress along the center of the shorter side of a rectangular cross section subjected to a torque. The results of this optimization process are shown to be highly accurate and easy to apply. It is believed that this is the first time that this approach has been applied to find this component of the shear stress. This paper includes an example application to illustrate the use of the approximate polynomials developed. The results are shown to be especially relevant to rectangular members that are subjected to combined torsion and bending.
Codes for Approximating Lyapunov Exponents
Authors: Dieci Luca , Jolly Michael S. , Van Vleck Erik S.
Published: July 2010

We present a suite of codes for approximating Lyapunov exponents of nonlinear differential systems by so-called QR methods. The basic solvers perform integration of the trajectory and approximation of the Lyapunov exponents simultaneously. That is, they integrate for the trajectory at the same time, and with the same underlying schemes, as integration for the Lyapunov exponents is carried out. Separate codes solve small systems for which we can compute and store the Jacobian matrix, and for large systems for which the Jacobian matrix cannot be stored, and it may not even be explicitly known. If it is known, the user has the option to provide its action on a vector. An alternative strategy is also presented in which one may want to approximate the trajectory with a specialized solver, linearize around the computed trajectory, and then carry out the approximation of the Lyapunov exponents using codes for linear problems.
Numerical Study on the Application of Chaos in Line Spectrum Reduction
Authors: Lou Jingjun , Zhu Shijian
Published: July 2010

The application of chaos method in line spectrum reduction is numerically studied. The nonlinear dynamics and the power flow transmissibility of a two-degree-of-freedom vibration isolation system with nonlinear spring are analyzed. The dynamic behavior distribution chart of the system is obtained. Cascades of bifurcation of the system with different excitation amplitude are also gained. The isolation effectiveness is analyzed from the point of view of energy. The numerical results show that the reduction of the line spectrum in chaotic state is much greater than that in non-chaotic state.
A Pilot Study to Assess Designer’s Mental Stress Using Eye Gaze System and Electroencephalogram
Authors: Petkar Harshad , Dande Shivangi , Yadav Rajeev , Zeng Yong , Nguyen Thanh An
Published: July 2010

The study of mental stress is of great importance to design in that it enhances our understanding of designer’s cognitive model during the creative design process, among others. As the first step of this effort, this paper focuses on the assessment of mental stress based on the analysis of electroencephalogram (EEG) signals and the eye related data. The stress stimuli used is the computer based Stroop test with six difficulty levels. By using different parameters such as EEG power bands, and other eye behavior data, human mental stresses were assessed. Results indicate a strong correlation between the recorded physiological signals and the emotional state of the designers. This study provides a baseline for the further analysis of designer’s and users mental stresses during design-related tasks.
Organising and Contextualising Engineering Business Information Through the Application of Faceted Classification
Authors: Giess M. D. , Zhao Y. , Darlington M. J. , Culley S. J. , McMahon C. A.
Published: July 2010

This paper discusses the construction of an organisational scheme for application within a bespoke Information Management system, intended to support the retrieval of Business Information across a large engineering company. In order to mitigate viewpoint dependency and to provide additional context to support the valuation of retrieved information, a Faceted Classification scheme was developed. This paper discusses the approach taken to this development and how the ideas of information valuation were integrated.
Low Cost Rapidly Reconfigurable UAV Autopilot for Research and Development of Guidance, Navigation and Control Algorithms
Authors: Lizarraga M. I. , Elkaim G. H. , Horn G. M. , Curry R. , Dobrokhodov V. , Kaminer I.
Published: July 2010

This paper presents the development and preliminary results of a rapidly reconfigurable autopilot for small Unmanned Aerial Vehicles. The autopilot presented differs from current commercial and open source autopilots mainly as it has been designed to: (i) be easily reprogrammable via Simulink (models are directly transferred to the autopilot through the Real-Time Workshop’s code-generation capability); (ii) decouple the traditional tasks of attitude estimation/navigation and flight control by using two Digital Signal Controllers (one for each task) interconnected via a Serial Peripheral Interface; and, (iii) being able to interact directly with Simulink as a Hardware-in-the-Loop simulator. This work details each of the main components of the autopilot and its ground control station software. Preliminary results for sensor calibration, Hardware-in-the-loop, ground and flight tests are presented.
Developing a Numerical Simulation Software for 3D Multibody Systems Based on a Unified Computational Modeling Technique
Authors: Shokouhfar Shahram , Khorsandijou Sayyid Mahdi
Published: July 2010

This article represents the features and capabilities of a newly developed application namely MASS (Mechanisms Analysis and Simulation Software) and the formulation and techniques therein. MASS is a general C++ application program whose main task is to construct and solve the governing algebraic differential motion equations of 3D multibody systems automatically in matrix forms complying with the computational algorithms required for numerical simulation. Newton-Raphson and SVD methods have been used for kinematical assembling and producing consistent initial conditions. Adaptive time-step Runge-Kutta-Fehlberg numerical integration methods might be used for forward dynamics problems. The governing equations perfectly describe the kinematics and dynamics of multibody systems within which 3D kinematical joints and collisions between rigid bodies might be taken into consideration. The unified computational technique for mathematical modeling of kinematical joints is the most important concept on top of which MASS has been implemented. It has occurred due to the existence of thirteen basic kinematical constraint equations. Each kinematical joint might be defined by a set of algebraic equations being selected from the mentioned basic equations. The unified dynamic models for collisions and impulsive loads have been also achieved using the mentioned technique. Simulation results obtained from MASS have been compared with that of the corresponding software of Working Model ver. 6 and a discussion about the coincidences and differences has been exposed.