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2011

Cleveland State University

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Articles 1 - 30 of 86

Full-Text Articles in Engineering

Uwb System Based On Energy Detection Of Derivatives Of The Gaussian Pulse, Song Cui, Fuqin Xiong Dec 2011

Uwb System Based On Energy Detection Of Derivatives Of The Gaussian Pulse, Song Cui, Fuqin Xiong

Electrical and Computer Engineering Faculty Publications

A new method for energy detection ultra-wideband systems is proposed. The transmitter of this method uses two pulses that are different-order derivatives of the Gaussian pulse to transmit bit 0 or 1. These pulses are appropriately chosen to separate their spectra in the frequency domain. The receiver is composed of two energydetection branches. Each branch has a filter which captures the signal energy of either bit 0 or 1. The outputs of the two branches are subtracted from each other to generate the decision statistic. The value of this decision statistic is compared to the threshold to determine the transmitted …

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Trustworthy Coordination For Web Services Atomic Transactions, Honglei Zhang, Hua Chai, Wenbing Zhao, P.M. Melliar-Smith, L.E. Moser Dec 2011

Trustworthy Coordination For Web Services Atomic Transactions, Honglei Zhang, Hua Chai, Wenbing Zhao, P.M. Melliar-Smith, L.E. Moser

Electrical and Computer Engineering Faculty Publications

The Web Services Atomic Transactions (WS-AT) specification makes it possible for businesses to engage in standard distributed transaction processing over the Internet using Web Services technology. For such business applications, trustworthy coordination of WS-AT is crucial. In this paper, we explain how to render WS-AT coordination trustworthy by applying Byzantine Fault Tolerance (BFT) techniques. More specifically, we show how to protect the core services described in the WS-AT specification, namely, the Activation service, the Registration service, the Completion service and the Coordinator service, against Byzantine faults. The main contribution of this work is that it exploits the semantics of the …

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Accelerated Fatigue Crack Growth Simulation In A Bimaterial Interface, R. Moslemian, Anette M. Karlsson, C. Berggreen Dec 2011

Accelerated Fatigue Crack Growth Simulation In A Bimaterial Interface, R. Moslemian, Anette M. Karlsson, C. Berggreen

Mechanical Engineering Faculty Publications

A method for accelerated simulation of fatigue crack growth in a bimaterial interface (e.g. in a face/core sandwich interface) is proposed. To simulate fatigue crack growth, a routine is incorporated in the commercial finite element program ANSYS and a method to accelerate the simulation is implemented. The proposed method (the cycle jump technique) is based on conducting finite element analysis for a set of cycles to establish a trend line, extrapolating the trend line spanning many cycles, and use the extrapolated state as initial state for additional finite element simulations. A control criterion is utilized to ensure the accuracy of …

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Field-Controlled Electron Transfer And Reaction Kinetics Of The Biological Catalytic System Of Microperoxidase-11 And Hydrogen Peroxide, Yongki Chou, Siu-Tung Yau Dec 2011

Field-Controlled Electron Transfer And Reaction Kinetics Of The Biological Catalytic System Of Microperoxidase-11 And Hydrogen Peroxide, Yongki Chou, Siu-Tung Yau

Electrical and Computer Engineering Faculty Publications

Controlled reaction kinetics of the bio-catalytic system of microperoxidase-11 and hydrogen peroxide has been achieved using an electrostatic technique. The technique allowed independent control of 1) the thermodynamics of the system using electrochemical setup and 2) the quantum mechanical tunneling at the interface between microperoxidase-11 and the working electrode by applying a gating voltage to the electrode. The cathodic currents of electrodes immobilized with microperoxidase-11 showed a dependence on the gating voltage in the presence of hydrogen peroxide, indicating a controllable reduction reaction. The measured kinetic parameters of the bio-catalytic reduction showed nonlinear dependences on the gating voltage as the …

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Field-Effect Amperometric Immuno-Detection Of Protein Biomarker, Jiapeng Wang, Siu-Tung Yau Nov 2011

Field-Effect Amperometric Immuno-Detection Of Protein Biomarker, Jiapeng Wang, Siu-Tung Yau

Electrical and Computer Engineering Faculty Publications

The field-effect enzymatic detection technique has been applied to the amperometric immunoassay of the cancer biomarker, carcinoma antigen 125 (CA 125). The detection adopted a reagentless approach, in which the analyte, CA 125, was immobilized on the detecting electrode, which was modified using carbon nanotubes, and the detection signal was obtained by measuring the reduction peak current of the enzyme that was used to label the antibody. A gating voltage was applied to the detecting electrode, inducing increase in the signal current and therefore providing amplification of the detection signal. The voltage-controlled signal amplification of the detection …

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Towards Trustworthy Coordination For Web Services Business Activities, Hua Chai, Hongle Zhang, Wenbing Zhao, P. M. Melliar-Smith, L. E. Moser Nov 2011

Towards Trustworthy Coordination For Web Services Business Activities, Hua Chai, Hongle Zhang, Wenbing Zhao, P. M. Melliar-Smith, L. E. Moser

Electrical and Computer Engineering Faculty Publications

We present a lightweight Byzantine fault tolerance (BFT) algorithm, which can be used to render the coordination of web services business activities (WS-BA) more trustworthy. The lightweight design of the BFT algorithm is the result of a comprehensive study of the threats to the WS-BA coordination services and a careful analysis of the state model of WS-BA. The lightweight BFT algorithm uses source ordering, rather than total ordering, of incoming requests to achieve Byzantine fault tolerant, state-machine replication of the WS-BA coordination services. We have implemented the lightweight BFT algorithm, and incorporated it into the open-source Kandula framework, which implements …

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Aspects Of Fatigue Failure Mechanisms In Polymer Fuel Cell Membranes, Ahmet Kusoglu, Michael H. Santare, Anette M. Karlsson Nov 2011

Aspects Of Fatigue Failure Mechanisms In Polymer Fuel Cell Membranes, Ahmet Kusoglu, Michael H. Santare, Anette M. Karlsson

Mechanical Engineering Faculty Publications

The swelling-driven fatigue behavior of polymer fuel cell membranes during relative humidity (RH) cycling is investigated. In particular, swelling-induced membrane stresses are obtained from a numerical model simulating fuel cell RH cycle tests, and compared to the lifetimes obtained experimentally from tests conducted in the absence of electrochemical effects. A strong correlation between the lifetimes of the membranes in the actual tests and model results is obtained. In general, higher RH (or swelling) amplitude results in larger stress amplitudes and shorter lifetime, that is, fewer cycles to failure. Tensile stresses are needed for forming local cavities in the membrane, which …

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2011 Scholars And Artists Bibliography, Michael Schwartz Library, Cleveland State University, Friends Of The Michael Schwartz Library, Mark Tebeau Oct 2011

2011 Scholars And Artists Bibliography, Michael Schwartz Library, Cleveland State University, Friends Of The Michael Schwartz Library, Mark Tebeau

Scholars and Artists Bibliographies

This bibliography was created for the annual Friends of the Michael Schwartz Library Scholars and Artists Reception, recognizing scholarly and creative achievements of Cleveland State University faculty, staff and emeriti. Mark Tebeau was the guest speaker

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Optimal Design Of Trusses With Geometric Imperfections: Accounting For Global Instability, Mehdi Jalalpour, Takeru Igusa, James K. Guest Oct 2011

Optimal Design Of Trusses With Geometric Imperfections: Accounting For Global Instability, Mehdi Jalalpour, Takeru Igusa, James K. Guest

Civil and Environmental Engineering Faculty Publications

A topology optimization method is proposed for the design of trusses with random geometric imperfections due to fabrication errors. This method is a generalization of a previously developed perturbation approach to topology optimization under geometric uncertainties. The main novelty in the present paper is that the objective function includes the nonlinear effects of potential buckling due to misaligned structural members. Solutions are therefore dependent on the magnitude of applied loads and the direction of resulting internal member forces (whether they are compression or tension). Direct differentiation is used in the sensitivity analysis, and analytical expressions for the associated derivatives are …

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Exploration Of Nde Properties Of Amb Supported Rotors For Structural Damage Detection, Jerzy T. Sawicki, Dmitry L. Storozhev, John D. Lekki Oct 2011

Exploration Of Nde Properties Of Amb Supported Rotors For Structural Damage Detection, Jerzy T. Sawicki, Dmitry L. Storozhev, John D. Lekki

Mechanical Engineering Faculty Publications

Recent advancements in actuator technology, power electronics, sensors, and signal processing have created a rapid development of smart machine technologies for rotating machinery. Ranging from machine condition monitoring and diagnostics to full active control of machine behavior, the integration of electrical and computer systems has produced significant advances in machine performance and reliability. Magnetic bearings are a typical mechatronics product. The hardware is composed of mechanical components combined with electronic elements such as sensors and power amplifiers and an information processing part, usually in the form of a microprocessor. In addition, an increasingly important part is software, which specifies the …

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A Multi-Regulator Sliding Mode Control Strategy For Output-Constrained Systems, Hanz Richter Oct 2011

A Multi-Regulator Sliding Mode Control Strategy For Output-Constrained Systems, Hanz Richter

Mechanical Engineering Faculty Publications

This paper proposes a multi-regulator control scheme for single-input systems, where the setpoint of a regulated output must be changed under the constraint that a set of minimum-phase outputs remain within prescribed bounds. The strategy is based on a max–min selector system frequently used in the aerospace field. The regulators used for the regulated and limited outputs are of the sliding mode type, where the sliding variable is defined as the difference between an output and its allowable limit. The paper establishes overall asymptotic stability, as well as invariance properties leading to limit protection. The design methodology is illustrated with …

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Review Of "Handbook For Blast Resistent Design Of Buildings", Norbert J. Delatte Sep 2011

Review Of "Handbook For Blast Resistent Design Of Buildings", Norbert J. Delatte

Civil and Environmental Engineering Faculty Publications

No abstract provided.

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Case Methods In Civil Engineering Teaching, Timothy A. Newson, Norbert J. Delatte Sep 2011

Case Methods In Civil Engineering Teaching, Timothy A. Newson, Norbert J. Delatte

Civil and Environmental Engineering Faculty Publications

English: There have been significant changes in undergraduate civil engineering curricula in the last two decades. Key issues for university curriculum committees are selection and transference of appropriate skills and attributes for students to succeed in the industry. Despite significant changes occurring in teaching theories, civil engineering education still relies heavily on deductive instruction. Case-based teaching is one of the most widespread forms of inductive learning and this paper describes the differences between two of the most familiar types: 'case-histories' and 'case-studies'. These methods are presented using the Kansas City Hyatt Regency walkway collapse as an exemplar. The benefits of …

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Analysis Of Migration Models Of Biogeography-Based Optimization Using Markov Theory, Haiping Ma, Daniel J. Simon Sep 2011

Analysis Of Migration Models Of Biogeography-Based Optimization Using Markov Theory, Haiping Ma, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Biogeography-based optimization (BBO) is a new evolutionary algorithm inspired by biogeography, which involves the study of the migration of biological species between habitats. Previous work has shown that various migration models of BBO result in significant changes in performance. Sinusoidal migration models have been shown to provide the best performance so far. Motivated by biogeography theory and previous results, in this paper a generalized sinusoidal migration model curve is proposed. A previously derived BBO Markov model is used to analyze the effect of migration models on optimization performance, and new theoretical results which are confirmed with simulation results are obtained. …

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The Eigenvalues Of A Tridiagonal Matrix In Biogeography, Boris Igelnik, Daniel J. Simon Sep 2011

The Eigenvalues Of A Tridiagonal Matrix In Biogeography, Boris Igelnik, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

We derive the eigenvalues of a tridiagonal matrix with a special structure. A conjecture about the eigenvalues was presented in a previous paper, and here we prove the conjecture. The matrix structure that we consider has applications in biogeography theory.

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In Situ Analysis Of Crack Propagation In Polymer Foams, Elio E. Saenz, Leif A. Carlsson, Anette M. Karlsson Aug 2011

In Situ Analysis Of Crack Propagation In Polymer Foams, Elio E. Saenz, Leif A. Carlsson, Anette M. Karlsson

Mechanical Engineering Faculty Publications

This article presents an experimental study on the microscopic mechanisms associated with crack propagation in closed cell polymer foams. A brittle, slightly cross-linked polyvinyl chloride (PVC) foam of density 60 kg/m3 and a ductile thermoplastic polyether sulfone (PES) foam of density 90 kg/m3 were examined. The PVC and PES foams have similar cell size (≈0.7 mm) but the cell edges of the PES foam were much thicker than those in the PVC foam. Overall, it was observed that the elements of both foams fractured in an extensional mode. Crack propagation in the PVC foam was inter-cellular, where agglomerates …

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On The Opening Of A Class Of Fatigue Cracks Due To Thermo-Mechanical Fatigue Testing Of Thermal Barrier Coatings, M. T. Hernandez, D. Cojocaru, M. Bartsch, Anette M. Karlsson Jul 2011

On The Opening Of A Class Of Fatigue Cracks Due To Thermo-Mechanical Fatigue Testing Of Thermal Barrier Coatings, M. T. Hernandez, D. Cojocaru, M. Bartsch, Anette M. Karlsson

Mechanical Engineering Faculty Publications

The evolution of fatigue cracks observed in thermal barrier coatings (TBCs) subjected to an accelerated test scheme is investigated via numerical simulations. The TBC system consists of a NiCoCrAlY bond coat and partially yttria stabilized zirconia top coat with a thermally grown oxide (TGO) between these two coatings. The cracks of interest evolve in the bond coat parallel and near the interface with the TGO during thermo-mechanical fatigue testing. In their final stage, the cracks lead to partial spallation of the TBC. This study focuses on why the cracks open to their characteristic shape. To this end, finite element simulations …

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A Probabilistic Analysis Of A Simplified Biogeography-Based Optimization Algorithm, Daniel J. Simon Jul 2011

A Probabilistic Analysis Of A Simplified Biogeography-Based Optimization Algorithm, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Biogeography-based optimization (BBO) is a population-based evolutionary algorithm (EA) that is based on the mathematics of biogeography. Biogeography is the study of the geographical distribution of biological organisms. We present a simplified version of BBO and perform an approximate analysis of the BBO population using probability theory. Our analysis provides approximate values for the expected number of generations before the population's best solution improves, and the expected amount of improvement. These expected values are functions of the population size. We quantify three behaviors as the population size increases: first, we see that the best solution in the initial randomly generated …

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On Active Disturbance Rejection Based Control Design For Supercomputing Rf Cavities, John Vincent, Dan Morris, Nathan Usher, Zhiqiang Gao, Shen Zhao, Achille Nicoletti, Qinling Zheng Jul 2011

On Active Disturbance Rejection Based Control Design For Supercomputing Rf Cavities, John Vincent, Dan Morris, Nathan Usher, Zhiqiang Gao, Shen Zhao, Achille Nicoletti, Qinling Zheng

Electrical and Computer Engineering Faculty Publications

Superconducting RF (SRF) cavities are key components of modern linear particle accelerators. The National Superconducting Cyclotron Laboratory (NSCL) is building a 3 MeV/u re-accelerator (ReA3) using SRF cavities. Lightly loaded SRF cavities have very small bandwidths (high Q) making them very sensitive to mechanical perturbations whether external or self-induced. Additionally, some cavity types exhibit mechanical responses to perturbations that lead to high-order non-stationary transfer functions resulting in very complex control problems. A control system that can adapt to the changing perturbing conditions and transfer functions of these systems would be ideal. This paper describes the application of a control …

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A Silicon Nanoparticle-Based Polymeric Nano-Composite Material For Glucose Sensing, Qiang Liu, Munir H. Nayfeh, Siu-Tung Yau Jul 2011

A Silicon Nanoparticle-Based Polymeric Nano-Composite Material For Glucose Sensing, Qiang Liu, Munir H. Nayfeh, Siu-Tung Yau

Electrical and Computer Engineering Faculty Publications

A novel non-enzyme glucose sensing material has been prepared by incorporating ultrasmall (1–3 nm) silicon nanoparticles in polyaniline, a conducting polymer, as a nano-composite material (NCM). When deposited on electrodes, the composite material with three-dimensional loading of the nanoparticles showed a significantly enhanced amperometric response to glucose, compared to the nanoparticles deposited on bare electrodes and electrodes immobilized with the enzyme, glucose oxidase. The linear range of the glucose response of NCM electrodes covered both the hypo- and hyper-glycaemic glucose levels. The sensitivity of the NCM electrodes was 2.5 μA cm−2 mM−1. The NCM electrodes’ selectivity for …

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On Active Disturbance Rejection Based Control Design For Superconducting Rf Cavities, John Vincent, Dan Morris, Nathan Usher, Zhiqiang Gao, Shen Zhaob, Achille Nicoletti, Qinling Zheng Jul 2011

On Active Disturbance Rejection Based Control Design For Superconducting Rf Cavities, John Vincent, Dan Morris, Nathan Usher, Zhiqiang Gao, Shen Zhaob, Achille Nicoletti, Qinling Zheng

Electrical and Computer Engineering Faculty Publications

Superconducting RF (SRF) cavities are key components of modern linear particle accelerators. The National Superconducting Cyclotron Laboratory (NSCL) is building a 3 MeV/u re-accelerator (ReA3) using SRF cavities. Lightly loaded SRF cavities have very small bandwidths (high Q) making them very sensitive to mechanical perturbations whether external or self-induced. Additionally, some cavity types exhibit mechanical responses to perturbations that lead to high-order non-stationary transfer functions resulting in very complex control problems. A control system that can adapt to the changing perturbing conditions and transfer functions of these systems would be ideal. This paper describes the application of a control technique …

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A Direct Sampling Particle Filter From Approximate Conditional Density Function Supported On Constrained State Space, Sridhar Ungarala Jun 2011

A Direct Sampling Particle Filter From Approximate Conditional Density Function Supported On Constrained State Space, Sridhar Ungarala

Chemical & Biomedical Engineering Faculty Publications

Constraints on the state vector must be taken into account in the state estimation problem. Recently, acceptance/rejection and projection methods are proposed in the particle filter framework for constraining the particles. A weighted least squares formulation is used for constraining samples in unscented and ensemble Kalman filters. In this paper, direct sampling from an approximate conditional probability density function (pdf) is proposed. It is obtained by approximating the a priori pdf as a Gaussian. The support of the conditional density is a subset of the intersection of two supports, the 3-sigma bounds of the priori Gaussian and the constrained state …

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Design And Implementation Of A Byzantine Fault Tolerance Framework For Non-Deterministic Applications, H. Zhang, Wenbing Zhao, Louise E. Moser, P. Michael Melliar-Smith Jun 2011

Design And Implementation Of A Byzantine Fault Tolerance Framework For Non-Deterministic Applications, H. Zhang, Wenbing Zhao, Louise E. Moser, P. Michael Melliar-Smith

Electrical and Computer Engineering Faculty Publications

State-machine-based replication is an effective way to increase the availability and dependability of mission-critical applications. However, all practical applications contain some degree of non-determinism. Consequently, ensuring strong replica consistency in the presence of application non-determinism has been one of the biggest challenges in building dependable distributed systems. In this Study, the authors propose a classification of common types of application non-determinism with respect to the requirement of achieving Byzantine fault tolerance (BFT), and present the design and implementation of a BFT framework that controls these types of non-determinism in a systematic manner.

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Fuzzy Robot Controller Tuning With Biogeography-Based Optimization, George Thomas, Paul Lozovyy, Daniel J. Simon Jun 2011

Fuzzy Robot Controller Tuning With Biogeography-Based Optimization, George Thomas, Paul Lozovyy, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Biogeography-based optimization (BBO) is an evolutionary algorithm (EA) based upon the models of biogeography, which describe the relationship between habitat suitability and the migration of species across habitats. In this work, we apply BBO to the problem of tuning the fuzzy tracking controller of mobile robots. This is an extension of previous work, in which we used BBO to tune a proportional-derivative (PD) controller for these robots. We show that BBO can successfully tune the shape of membership functions for a fuzzy controller with both simulation and real world experimental results.

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Distributed Learning With Biogeography-Based Optimization, Carre Scheidegger, Arpit Shah, Daniel J. Simon Jun 2011

Distributed Learning With Biogeography-Based Optimization, Carre Scheidegger, Arpit Shah, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

We present hardware testing of an evolutionary algorithm known as biogeography-based optimization (BBO) and extend it to distributed learning. BBO is an evolutionary algorithm based on the theory of biogeography, which describes how nature geographically distributes organisms. We introduce a new BBO algorithm that does not use a centralized computer, and which we call distributed BBO. BBO and distributed BBO have been developed by mimicking nature to obtain an algorithm that optimizes solutions for different situations and problems. We use fourteen common benchmark functions to obtain results from BBO and distributed BBO, and we also use both algorithms to optimize …

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Characterization Of Fracture Toughness G (Sub C) Of Pvc And Pes Foams, Elio E. Saenz, Leif A. Carlsson, Anette M. Karlsson May 2011

Characterization Of Fracture Toughness G (Sub C) Of Pvc And Pes Foams, Elio E. Saenz, Leif A. Carlsson, Anette M. Karlsson

Mechanical Engineering Faculty Publications

The fracture behavior of polyvinyl chloride (PVC) and polyethersulfone (PES) foams has been examined using the single-edge notch bend and the double cantilever beam (DCB) tests. PVC foam densities ranging from 45 to 100 kg/m3 and PES foam densities ranging from 60 to 130 kg/m3 were examined. The PVC foams failed in a linear elastic brittle manner, whereas the PES foams displayed much more ductility and substantially larger toughness at a comparable foam density. The cell wall thickness of the PES foams was almost twice the thickness of the PVC foams which may have contributed to the high …

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Behavior-Based Mobility Prediction For Seamless Handoffs In Mobile Wireless Networks, Weetit Wanalertlak, Ben Lee, Chansu Yu, Myungchul Kim, Seung-Min Park, Won-Tae Kim Apr 2011

Behavior-Based Mobility Prediction For Seamless Handoffs In Mobile Wireless Networks, Weetit Wanalertlak, Ben Lee, Chansu Yu, Myungchul Kim, Seung-Min Park, Won-Tae Kim

Electrical and Computer Engineering Faculty Publications

The field of wireless networking has received unprecedented attention from the research community during the last decade due to its great potential to create new horizons for communicating beyond the Internet. Wireless LANs (WLANs) based on the IEEE 802.11 standard have become prevalent in public as well as residential areas, and their importance as an enabling technology will continue to grow for future pervasive computing applications. However, as their scale and complexity continue to grow, reducing handoff latency is particularly important. This paper presents the Behavior-based Mobility Prediction scheme to eliminate the scanning overhead incurred in IEEE 802.11 networks. This …

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Blended Biogeography-Based Optimization For Constrained Optimization, Haiping Ma, Daniel J. Simon Apr 2011

Blended Biogeography-Based Optimization For Constrained Optimization, Haiping Ma, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Biogeography-based optimization (BBO) is a new evolutionary optimization method that is based on the science of biogeography. We propose two extensions to BBO. First, we propose a blended migration operator. Benchmark results show that blended BBO outperforms standard BBO. Second, we employ blended BBO to solve constrained optimization problems. Constraints are handled by modifying the BBO immigration and emigration procedures. The approach that we use does not require any additional tuning parameters beyond those that are required for unconstrained problems. The constrained blended BBO algorithm is compared with solutions based on a stud genetic algorithm (SGA) and standard particle swarm …

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Analytical And Numerical Comparisons Of Biogeography-Based Optimization And Genetic Algorithms., Daniel J. Simon, Rick Rarick, Mehmet Ergezer, Dawei Du Apr 2011

Analytical And Numerical Comparisons Of Biogeography-Based Optimization And Genetic Algorithms., Daniel J. Simon, Rick Rarick, Mehmet Ergezer, Dawei Du

Electrical and Computer Engineering Faculty Publications

We show that biogeography-based optimization (BBO) is a generalization of a genetic algorithm with global uniform recombination (GA/GUR). Based on the common features of BBO and GA/GUR, we use a previously-derived BBO Markov model to obtain a GA/GUR Markov model. One BBO characteristic which makes it distinctive from GA/GUR is its migration mechanism, which affects selection pressure (i.e., the probability of retaining certain features in the population from one generation to the next). We compare the BBO and GA/GUR algorithms using results from analytical Markov models and continuous optimization benchmark problems. We show that the unique selection pressure provided by …

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Detecting Cracked Rotors Using Auxiliary Harmonic Excitation, Jerzy T. Sawicki, Michael I. Friswell, Zbigniew Kulesza, Adam C. Wroblewski, John D. Lekki Mar 2011

Detecting Cracked Rotors Using Auxiliary Harmonic Excitation, Jerzy T. Sawicki, Michael I. Friswell, Zbigniew Kulesza, Adam C. Wroblewski, John D. Lekki

Mechanical Engineering Faculty Publications

Cracked rotors are not only important from a practical and economic viewpoint, they also exhibit interesting dynamics. This paper investigates the modelling and analysis of machines with breathing cracks, which open and close due to the self-weight of the rotor, producing a parametric excitation. After reviewing the modelling of cracked rotors, the paper analyses the use of auxiliary excitation of the shaft, often implemented using active magnetic bearings to detect cracks. Applying a sinusoidal excitation generates response frequencies that are combinations of the rotor spin speed and excitation frequency. Previously this system was analysed using multiple scales analysis; this paper …

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