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2005

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An Elementary Method For Calculating Orientation-Averaged Fully Differential Electron-Impact Ionization Cross Sections For Molecules, Junfang Gao, Jerry Peacher, Don H. Madison Jan 2005

An Elementary Method For Calculating Orientation-Averaged Fully Differential Electron-Impact Ionization Cross Sections For Molecules, Junfang Gao, Jerry Peacher, Don H. Madison

Physics Faculty Research & Creative Works

Currently there are no reliable theoretical approaches for calculating fully differential cross sections (FDCS) for low-energy electron-impact ionization of large molecules. We have recently introduced the distorted-wave impulse approximation as a first step in developing improved theoretical approaches. One significant obstacle to evaluating improved theoretical approaches which require significant computer resources lies in the fact that the existing experimental data require taking averages over all molecular orientations. To circumvent this problem, it has been proposed to approximate the orientation-average by using an orientation-averaged molecular orbital in the calculation of the FDCS. The theoretical justification and expected range of validity for …

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Critical Behavior And Griffiths Effects In The Disordered Contact Process, Thomas Vojta, Mark Dickison Jan 2005

Critical Behavior And Griffiths Effects In The Disordered Contact Process, Thomas Vojta, Mark Dickison

Physics Faculty Research & Creative Works

We study the nonequilibrium phase transition in the one-dimensional contact process with quenched spatial disorder by means of large-scale Monte Carlo simulations for times up to 109 and system sizes up to 107 sites. In agreement with recent predictions of an infinite-randomness fixed point, our simulations demonstrate activated (exponential) dynamical scaling at the critical point. The critical behavior turns out to be universal, even for weak disorder. However, the approach to this asymptotic behavior is extremely slow, with crossover times of the order of 104 or larger. In the Griffiths region between the clean and the dirty critical points, we …

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Fully Differential Cross Sections For Low-Energy Electron-Impact Ionization Of Nitrogen Molecules, Junfang Gao, Don H. Madison, Jerry Peacher Jan 2005

Fully Differential Cross Sections For Low-Energy Electron-Impact Ionization Of Nitrogen Molecules, Junfang Gao, Don H. Madison, Jerry Peacher

Physics Faculty Research & Creative Works

Currently there is no accurate theoretical approach available for treating fully differential cross sections (FDCS) for low-energy electron-impact ionization of large molecules. For high incident energies, the plane wave impulse approximation (PWIA) generally yields good agreement with experimental data. In this paper, the distorted wave impulse approximation (DWIA) is used to calculate FDCS for low-energy electron-impact ionization of N2. To perform the necessary average over all molecular orientations, we propose an orientation average (OA) approximation. Although the DWIA results represent an improvement over the PWIA for intermediate energies, an improved theory is necessary for lower energies. However, the OA approximation …

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Half-Metallicity And Efficient Spin Injection In Aln/Gan:Cr (0001) Heterostructure, Julia E. Medvedeva, X. Y. Cui, C. Stampfl, N. Newman, Arthur J. Freeman Jan 2005

Half-Metallicity And Efficient Spin Injection In Aln/Gan:Cr (0001) Heterostructure, Julia E. Medvedeva, X. Y. Cui, C. Stampfl, N. Newman, Arthur J. Freeman

Physics Faculty Research & Creative Works

First-principles investigations of the structural, electronic, and magnetic properties of Cr-doped AlN/GaN (0001) heterostructures reveal the possibility of efficient spin injection from a ferromagnetic GaN:Cr electrode through an AlN tunnel barrier. We demonstrate that Cr atoms segregate into the GaN region and that these interfaces retain their half-metallic behavior leading to a complete, i.e., 100%, spin polarization of the conduction electrons. This property makes the wide band-gap nitrides doped with Cr to be excellent candidates for high-efficiency magnetoelectronic devices.

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Interference Effects For Low-Energy Electron-Impact Ionization Of Nitrogen Molecules, Junfang Gao, Don H. Madison, Jerry Peacher Jan 2005

Interference Effects For Low-Energy Electron-Impact Ionization Of Nitrogen Molecules, Junfang Gao, Don H. Madison, Jerry Peacher

Physics Faculty Research & Creative Works

Young's double slit interference effects for low incident energy 75.6 eV electron impact ionization of N2 are investigated using the distorted-wave impulse approximation (DWIA) for both coplanar symmetric and asymmetric scattering. Although the DWIA does not predict observable interference effects for the coplanar symmetric case, it predicts some strong Young's double-slit-type interference effects for the highly asymmetric scattering case. These effects are strong enough that they should be experimentally observable if one can make measurements in the backscattering region.

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Near-Field Intensity Correlations In Semicontinuous Metal-Dielectric Films, K. Seal, A. K. Sarychev, H. Noh, D. A. Genov, Alexey Yamilov, V. M. Shalaev, Z. C. Ying, Hui Cao Jan 2005

Near-Field Intensity Correlations In Semicontinuous Metal-Dielectric Films, K. Seal, A. K. Sarychev, H. Noh, D. A. Genov, Alexey Yamilov, V. M. Shalaev, Z. C. Ying, Hui Cao

Physics Faculty Research & Creative Works

Spatial intensity correlation functions are obtained from near-field scanning optical microscope measurements of semicontinuous metal-dielectric films. The concentration of metal particles on a dielectric surface is varied over a wide range to control the scattering strength. At low and high metal coverages where scattering is weak, the intensity correlation functions exhibit oscillations in the direction of incident light due to excitation of propagating surface waves. In the intermediate regime of metal concentration, the oscillatory behavior is replaced by a monotonic decay as a result of strong scattering and anomalous absorption. Significant differences in the near-field intensity correlations between metallic and …

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Precollision And Postcollision Electron-Electron Correlation Effects For Intermediate-Energy Proton-Impact Ionization Of Helium, M. Foster, Jerry Peacher, Michael Schulz, Ahmad Hasan, Don H. Madison Jan 2005

Precollision And Postcollision Electron-Electron Correlation Effects For Intermediate-Energy Proton-Impact Ionization Of Helium, M. Foster, Jerry Peacher, Michael Schulz, Ahmad Hasan, Don H. Madison

Physics Faculty Research & Creative Works

We report fully differential cross sections (FDCS) for the single ionization of helium by a 75 keV incident energy proton. Previous three-body distorted wave (3DW) calculations for this collision system are in poor agreement with the absolute magnitude of the experimental measurements. The 3DW approximation treats the four-body problem as an effective three-body problem in which the passive electron does not participate in the collision. We have developed a full four-body approach in which the passive electron fully participates in the collision. It will be shown that the FDCS is very sensitive to the treatment of the passive electron-ejected electron …

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Quantum Griffiths Effects In Itinerant Heisenberg Magnets, Thomas Vojta, Jörg Schmalian Jan 2005

Quantum Griffiths Effects In Itinerant Heisenberg Magnets, Thomas Vojta, Jörg Schmalian

Physics Faculty Research & Creative Works

We study the influence of quenched disorder on quantum phase transitions in itinerant magnets with Heisenberg spin symmetry, paying particular attention to rare disorder fluctuations. In contrast to the Ising case where the Landau damping of the spin fluctuations suppresses the tunneling of the rare regions, the Heisenberg system displays strong power-law quantum Griffiths singularities in the vicinity of the quantum critical point. We discuss these phenomena based on general scaling arguments, and we illustrate them by an explicit calculation for O(N) spin symmetry in the large-N limit. We also discuss broad implications for the classification of quantum phase transitions …

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Role Of Embedded Clustering In Dilute Magnetic Semiconductors: Cr Doped Gan, Julia E. Medvedeva, B. Delley, N. Newman, C. Stampfl, X. Y. Cui, Arthur J. Freeman Jan 2005

Role Of Embedded Clustering In Dilute Magnetic Semiconductors: Cr Doped Gan, Julia E. Medvedeva, B. Delley, N. Newman, C. Stampfl, X. Y. Cui, Arthur J. Freeman

Physics Faculty Research & Creative Works

Results of extensive density-functional studies provide direct evidence that Cr atoms in Cr:GaN have a strong tendency to form embedded clusters, occupying Ga sites. Significantly, for larger than 2-Cr-atom clusters, states containing antiferromagnetic coupling with net spin in the range 0.06-1.47 µB/Cr are favored. We propose a picture where various configurations coexist and the statistical distribution and associated magnetism will depend sensitively on the growth details. Such a view may elucidate many puzzling observations related to the structural and magnetic properties of III-N and other dilute semiconductors.

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The Effect Of Cu-Doping On The Magnetic And Transport Properties Of La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William B. Yelon, Paul Ernest Parris, William Joseph James Jan 2005

The Effect Of Cu-Doping On The Magnetic And Transport Properties Of La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William B. Yelon, Paul Ernest Parris, William Joseph James

Physics Faculty Research & Creative Works

The effects of Cu-doping on the structural, magnetic, and transport properties of La0.7Sr0.3Mn1xCuxO3 (0<=x<=0.20) have been studied using neutron diffraction, magnetization, and magnetoresistance (MR) measurements. All samples show the rhombohedral structure with the R[overline 3]c space-group from 10 K to room temperature (RT). Neutron diffraction data suggest that some of the Cu ions have a Cu3+ state in these compounds. The substitution of Mn by Cu affects the MnO bond length and Mn-O-Mn bond angle resulting from the minimization of the distortion of the MnO6 octahedron. Resistivity measurements show that a metal to insulator transition occurs for the x>=0.15 samples. The x=0.15 sample shows the highest MR([approximate]80%), which might result from the co-existence of Cu3-Cu2+ and the dilution effect of Cu-doping on the double exchange interaction

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Tunable Conductivity And Conduction Mechanism In An Ultraviolet Light Activated Electronic Conductor, Mariana I. Bertoni, Thomas O. Mason, Julia E. Medvedeva, Arthur J. Freeman, Kenneth R. Poeppelmeier, B. Delley Jan 2005

Tunable Conductivity And Conduction Mechanism In An Ultraviolet Light Activated Electronic Conductor, Mariana I. Bertoni, Thomas O. Mason, Julia E. Medvedeva, Arthur J. Freeman, Kenneth R. Poeppelmeier, B. Delley

Physics Faculty Research & Creative Works

A tunable conductivity has been achieved by controllable substitution of an ultraviolet light activated electronic conductor. The transparent conducting oxide system H-doped Ca12-xMgxAl14O33 (x=0,0.1,0.3,0.5,0.8,1.0) presents a conductivity that is strongly dependent on the substitution level and temperature. Four-point dc-conductivity decreases with x from 0.26 S/cm (x=0) to 0.106 S/cm (x=1) at room temperature. At each composition the conductivity increases (reversibly with temperature) until a decomposition temperature is reached; above this value, the conductivity drops dramatically due to hydrogen recombination and loss. The observed conductivity behavior is consistent with the predictions of our first principles density functional calculations for the Mg-substituted …

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Correlates Of Health Promotion: Meaning In Life, Religiosity, And Christian Identification, Daniel Melvin Huber Jan 2005

Correlates Of Health Promotion: Meaning In Life, Religiosity, And Christian Identification, Daniel Melvin Huber

Dissertations and Theses @ UNI

The relationships among meaning in life, religious orientation, Christian identity, health locus of control, and health promotion behaviors were assessed using 206 Christian students from a public university. Six areas of health promotion (physical activity, interpersonal relations, nutrition, health responsibility, spiritual growth, and stress management) were measured using the Health Promoting Lifestyle Profile-II. Predictions included (1) intrinsic religiosity, meaning in life, Christian identity, internal health locus of control, and God control will be positively associated with health promoting behaviors; and (2) intrinsic religiosity and internal health locus of control will be positive predictors of health promoting behaviors. Meaning in life …

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In The House Of The Mirrors: A Collection Of Short Stories, Adrián Fuentes Jan 2005

In The House Of The Mirrors: A Collection Of Short Stories, Adrián Fuentes

Dissertations and Theses @ UNI

"In the House of the Mirrors" is a compilation of short stories that question the concept of reality. These stories, however, do not only question reality but also supernaturalism, myth, and legend. Is there any magic in reality or are these two terms always in opposition with each other and can never coexist? What happens when we die? If the gods die, what happens when they die? Is our fate already predetermined or do we really have free will? These stories insist that there are events in life that we ignore because they do not fall in what we have …

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Comparison Of Non-Uniform Optimal Quantizer Designs For Speech Coding With Adaptive Critics And Particle Swarm, Wenwei Zha, Ganesh K. Venayagamoorthy Jan 2005

Comparison Of Non-Uniform Optimal Quantizer Designs For Speech Coding With Adaptive Critics And Particle Swarm, Wenwei Zha, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents the design of a companding non-uniform optimal scalar quantizer for speech coding. The quantizer is designed using two neural networks to perform the nonlinear transformation. These neural networks are used in the front and back ends of a uniform quantizer. Two approaches are presented in this paper namely adaptive critic designs (ACD) and particle swarm optimization (PSO), aiming to maximize the signal to noise ratio (SNR). The comparison of these optimal quantizer designs over bit rate range of 3 to 6 is presented. The perceptual quality of the coding is evaluated by the International Telecommunication Union''s Perceptual …

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Special Session - Team Training To Promote Constructive (Not Destructive) Conflict, Ray Luechtefeld, Steve Eugene Watkins Jan 2005

Special Session - Team Training To Promote Constructive (Not Destructive) Conflict, Ray Luechtefeld, Steve Eugene Watkins

Engineering Management and Systems Engineering Faculty Research & Creative Works

Advancing technology increases the need for engineering students to perform effectively on multidisciplinary teams. While conflict is a normal, and even necessary, component of team dynamics, if not managed effectively it can lead to destructive (rather than constructive) outcomes. An Action Science approach to group and individual effectiveness can help teams handle conflict constructively. This session uses a "Teach the Teacher" approach to give participants a basic understanding of skills underlying the approach. It provides practice in Action Science through a set of learning modules. These skills can be brought back and integrated into the participants' courses to provide student …

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Collaborative Global Software Development And Education, Xiaoqing Frank Liu Jan 2005

Collaborative Global Software Development And Education, Xiaoqing Frank Liu

Computer Science Faculty Research & Creative Works

In this position paper, challenges and issues with collaborative global software development and education are discussed. Suggestions are made to improve and strengthen software engineering education to adapt to it.

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Consistency Management Among Replicas In Peer-To-Peer Mobile Ad Hoc Networks, Sanjay Kumar Madria, Takahiro Hara Jan 2005

Consistency Management Among Replicas In Peer-To-Peer Mobile Ad Hoc Networks, Sanjay Kumar Madria, Takahiro Hara

Computer Science Faculty Research & Creative Works

Recent advances in wireless communication along with peer-to-peer (P2P) paradigm have led to increasing interest in P2P mobile ad hoc networks. In this paper, we assume an environment where each mobile peer accesses data items held by other peers which are connected by a mobile ad hoc network. Since peers' mobility causes frequent network partitions, replicas of a data item may be inconsistent due to write operations performed by mobile peers. In such an environment, the global consistency of data items is not desirable by many applications. Thus, new consistency maintenance based on local conditions such as location and time …

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Interactive Anatomy Online, Jennifer Leopold, Thomas Hoeft, Anne M. Maglia Jan 2005

Interactive Anatomy Online, Jennifer Leopold, Thomas Hoeft, Anne M. Maglia

Computer Science Faculty Research & Creative Works

The scientific community and general public can best take advantage of the benefits of 3D digital reconstructions if they are stored in a Web-accessible, easy-to-access database. We describe MorphologyNet/sup /spl copy// a Web-based digital library of realistic, 3D interactive and customizable images of anatomy currently in development at the University of Missouri-Rolla.

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Anisotropic Diffusion Of N-Butane And N-Decane On A Stepped Surface, Shrijay Subramaniyan, Jee-Ching Wang Jan 2005

Anisotropic Diffusion Of N-Butane And N-Decane On A Stepped Surface, Shrijay Subramaniyan, Jee-Ching Wang

Chemical and Biochemical Engineering Faculty Research & Creative Works

The diffusion of single n-butane and n-decane molecules on a model stepped surface, Pt(655), and on a corresponding flat surface, Pt(111), is investigated using molecular-dynamics simulations and anisotropic united atom model. The surface step on Pt(655) causes the alkane molecules to adsorb on the lower terrace in all-trans conformations with their long molecular axes adjacent and parallel to the step edge, and to diffuse anisotropically along the surface step via a constant wiggly motion without rotation or marked deviation from the parallel adsorption configuration. At relatively high temperatures, the alkane molecules can temporarily break away from the step edge but …

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Measurement And Prediction Of Pressure Drop In Pneumatic Conveying: Effect Of Particle Characteristics, Mass Loading, And Reynolds Number, Kimberly H. Henthorn, Kinam Park, Jennifer S. Curtis Jan 2005

Measurement And Prediction Of Pressure Drop In Pneumatic Conveying: Effect Of Particle Characteristics, Mass Loading, And Reynolds Number, Kimberly H. Henthorn, Kinam Park, Jennifer S. Curtis

Chemical and Biochemical Engineering Faculty Research & Creative Works

This paper reports the effect of Reynolds number, mass loading, and particle shape and size on pressure drop in a vertical gas-solids pneumatic conveying line. We isolate the effect of one variable while holding all others constant. A commonly used pressure drop correlation and a state-of-the-art multiphase computational fluid dynamics (CFD) models are then assessed by comparing their predictions to experimental data. Deficiencies in the models and the correlation are identified, and possible modifications are proposed. The most notable deficiency is the inability of both the experimental correlation and the CFD model to accurately predict the pressure drop for gas-solids …

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Wetting Kinetics Of Films Containing Non-Adsorbing Polymers, S. Saritha, Xianzhong Zhang, Partho Neogi Jan 2005

Wetting Kinetics Of Films Containing Non-Adsorbing Polymers, S. Saritha, Xianzhong Zhang, Partho Neogi

Chemical and Biochemical Engineering Faculty Research & Creative Works

Kinetics of wetting by a polymer solution have been studied theoretically for a film pinned to a slot. The fluid mechanical equations have been solved using a numerical scheme. The role of polymers appears in the disjoining pressure in the model. The spreading kinetics are observed to follow a power law: a power of (1/4) is observed at short times due to the Laplace pressure, and (1/2) at large times under the Hamaker part of the disjoining pressure at very large times and with no equilibration. It is argued and demonstrated that techniques which have low resolutions such as microscopy …

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Robust Resource Allocations In Parallel Computing Systems: Model And Heuristics, V. Shestak, Shoukat Ali, Howard Jay Siegel, A. A. Maciejewski Jan 2005

Robust Resource Allocations In Parallel Computing Systems: Model And Heuristics, V. Shestak, Shoukat Ali, Howard Jay Siegel, A. A. Maciejewski

Electrical and Computer Engineering Faculty Research & Creative Works

The resources in parallel computer systems (including heterogeneous clusters) should be allocated to the computational applications in a way that maximizes some system performance measure. However, allocation decisions and associated performance prediction are often based on estimated values of application and system parameters. The actual values of these parameters may differ from the estimates; for example, the estimates may represent only average values, the models used to generate the estimates may have limited accuracy, and there may be changes in the environment. Thus, an important research problem is the development of resource management strategies that can guarantee a particular system …

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Suitability Of Pulse Train Control Technique For Bifred Converter, Mehdi Ferdowsi, Ali Emadi, Mark Telefus, Anatoly Shteynberg Jan 2005

Suitability Of Pulse Train Control Technique For Bifred Converter, Mehdi Ferdowsi, Ali Emadi, Mark Telefus, Anatoly Shteynberg

Electrical and Computer Engineering Faculty Research & Creative Works

Pulse TrainTM control scheme is presented and applied to a boost integrated flyback rectifier/energy storage dc-dc (BIFRED) converter operating in discontinuous conduction mode (DCM), which avoids the light-load high-voltage stress problem. In contrast to the conventional control techniques, the principal idea of Pulse Train technique is to regulate the output voltage using a series of high and low energy pulses generated by the current of the inductor. The applicability of the proposed technique to both the input and magnetizing inductances of BIFRED converter is investigated. Analysis of BIFRED converter operating in DCM as well as the output voltage ripple …

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Traces In Proximity To Gaps In Return Planes, Todd H. Hubing, Thomas Van Doren, Theodore M. Zeeff Jan 2005

Traces In Proximity To Gaps In Return Planes, Todd H. Hubing, Thomas Van Doren, Theodore M. Zeeff

Electrical and Computer Engineering Faculty Research & Creative Works

Coupling between circuitry on printed circuit boards can be mitigated by a variety of well-known techniques. One such technique is to isolate circuitry in different areas of the printed circuit board by strategically placing a gap in the signal return plane. However, this technique is only effective at reducing common-impedance coupling, which is generally not a significant coupling mechanism at frequencies above 1 MHz. This paper investigates the effect of a gap located between and parallel to adjacent microstrip traces. The effect of the gap on the mutual inductance and mutual capacitance is evaluated. Laboratory measurements and numerical simulations show …

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Trends In Process Control Systems Security, Ann K. Miller Jan 2005

Trends In Process Control Systems Security, Ann K. Miller

Electrical and Computer Engineering Faculty Research & Creative Works

The protection of critical infrastructure systems is a hotly debated topic. The very label "critical infrastructure" implies that these systems are important, and they are: they support our everyday lives, from the water and food in our homes to our physical and financial welfare. This article explores the recent evolution of programmable logic controllers (PCSs) and their environments, explains the need for improved security in these systems, and describes some of the emerging research areas that offer promise in PCS security.

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Using An Lu Recombination Method To Improve The Performance Of The Boundary Element Method At Very Low Frequencies, Haixin Ke, Todd H. Hubing Jan 2005

Using An Lu Recombination Method To Improve The Performance Of The Boundary Element Method At Very Low Frequencies, Haixin Ke, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

Many numerical electromagnetic modeling techniques that work very well at high frequencies do not work well at lower frequencies. This is directly or indirectly due to the weak coupling between the electric and magnetic fields at low frequencies. One technique for improving the performance of boundary element techniques at low frequencies is through the use of loop-tree basis functions, which decouple the contributions from the vector and scalar electric potential. However, loop-tree basis functions can be difficult to define for large, complex geometries. This paper describes a new method for improving the low-frequency performance of boundary element techniques. The proposed …

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Wide Area Power System Protection Using A Learning Vector Quantization Network, Ganesh K. Venayagamoorthy, Mahyar Zarghami Jan 2005

Wide Area Power System Protection Using A Learning Vector Quantization Network, Ganesh K. Venayagamoorthy, Mahyar Zarghami

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a wide area monitoring and protection technique based on a learning vector quantization (LVQ) neural network. Phasor measurements of the power network buses are monitored continuously by a LVQ network in order to alert the control room operators of possible faults. The proposed scheme could be used in a wide area monitored network to provide remedial action when primary local protection schemes for transmission lines fail to function. This technique could also be extended to the actuation of the secondary protection schemes, hence, preserving the integrity of the power network especially when the faults are spreading over …

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A Dynamic Recurrent Neural Network For Wide Area Identification Of A Multimachine Power System With A Facts Device, Salman Mohagheghi, Ganesh K. Venayagamoorthy, Ronald G. Harley Jan 2005

A Dynamic Recurrent Neural Network For Wide Area Identification Of A Multimachine Power System With A Facts Device, Salman Mohagheghi, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

Multilayer perceptron and radial basis function neural networks have been traditionally used for plant identification in power systems applications of neural networks. While being efficient in tracking the plant dynamics in a relatively small system, their performance degrades as the dimensions of the plant to be identified are increased, for example in supervisory level identification of a multimachine power system for wide area control purposes. Recurrent neural networks can deal with such a problem by modeling the system as a set of differential equations and with less order of complexity. Such a recurrent neural network identifier is designed and implemented …

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A Heuristic-Dynamic-Programming-Based Power System Stabilizer For A Turbogenerator In A Single-Machine Power System, Wenxin Liu, Ganesh K. Venayagamoorthy, Donald C. Wunsch Jan 2005

A Heuristic-Dynamic-Programming-Based Power System Stabilizer For A Turbogenerator In A Single-Machine Power System, Wenxin Liu, Ganesh K. Venayagamoorthy, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

Power system stabilizers (PSSs) are used to generate supplementary control signals for the excitation system in order to damp the low-frequency power system oscillations. To overcome the drawbacks of a conventional PSS (CPSS), numerous techniques have been proposed in the literature. Based on the analysis of existing techniques, a novel design based on heuristic dynamic programming (HDP) is presented in this paper. HDP, combining the concepts of dynamic programming and reinforcement learning, is used in the design of a nonlinear optimal power system stabilizer. Results show the effectiveness of this new technique. The performance of the HDP-based PSS is compared …

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A Measure Of Robustness Against Multiple Kinds Of Perturbations, Shoukat Ali, Behdis Eslamnour Jan 2005

A Measure Of Robustness Against Multiple Kinds Of Perturbations, Shoukat Ali, Behdis Eslamnour

Electrical and Computer Engineering Faculty Research & Creative Works

Parallel and distributed heterogeneous computing systems may operate in an environment that undergoes unpredictable changes causing certain system performance features to degrade. Such systems need robustness to guarantee limited degradation despite fluctuations in the behavior of its component parts or environment. Our previous work in this area presented a method for generating a measure of robustness for a given system. However, the focus of that approach was on a scenario where all perturbations were of the same kind, e.g., all perturbations were in message sizes or computation times, but not both message sizes and computation times. This paper gives an …

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