Digital Commons Network^™

Dynamic Performance Of Isolated Power Converters, David Badia

Theses

Isolated power converters are primarily used in applications where electrical galvanic isolation is required for safety purposes. They are also used in applications, which require various output voltages level. They have been studied from many different aspects, but in this thesis the fundamental circuits of the flyback, the forward and the half-bridge converters are studied and compared extensively, with regard to their dynamic performance.

This analysis will lead us to a better understanding of their behaviour, that is a crucial point in the selection of each topology for a particular application. Moreover, the dynamic response of each converter is different; …

Power Quality, Badrul H. Chowdhury

Electrical and Computer Engineering Faculty Research & Creative Works

One big reason for the poor power quality incidents experienced today is the proliferation of electronic devices. A voracious appetite for higher efficiency and productivity in the manufacturing sector, comfort and automation in homes, and efficient lighting systems in commercial installations are driving the market for power electronic devices. At the forefront of this explosion is the switched power supply. Compared to its predecessor-the linear power supply-it can convert higher power much more efficiently and with a significantly smaller footprint. The switched power supply is found in most of today''s computers, fax machines, laser printers, office copiers, etc.

Analysis Of A Four-Level Dc/Dc Buck Converter, Keith Corzine, J. Yuen, J. R. Baker

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a four-level DC/DC buck converter is introduced. The primary application for this converter is to regulate the center capacitor voltage in a four-level inverter system. The steady-state and average-value models for the proposed converter are developed and compared in simulation. The converter was constructed in the laboratory and verified on a four-level motor drive system. It was shown that the four-level DC/DC converter provides capacitor voltage balancing and allows higher output voltage utilization from the inverter.

Detection And Classification Of Impact-Induced Damage In Composite Plates Using Neural Networks, Rohit Dua, Steve Eugene Watkins, Donald C. Wunsch, K. Chandrashekhara, Farhad Akhavan

Electrical and Computer Engineering Faculty Research & Creative Works

Artificial neutral networks (ANN) can be used as an online health monitoring systems (involving damage assessment, fatigue monitoring and delamination detection) for composite structures owing to their inherent fast computing speeds, parallel processing and ability to learn and adapt to the experimental data. The amount of impact-induced strain on a composite structure can be found using strain sensors attached to composite structures. Prior work has shown that strain-based ANN can characterize impact energy on composite plates and that strain signatures can be associated with damage types and severity. This paper reports the extension of this approach for damage classification using …

Design And Implementation Of A Biologically Realistic Olfactory Cortex In Analog Vlsi, Jose C. Principe, Vitor G. Tavares, John G. Harris, Walter J. Freeman

Electrical and Computer Engineering Faculty Research & Creative Works

This paper reviews the problem of translating signals into symbols preserving maximally the information contained in the signal time structure. In this context, we motivate the use of nonconvergent dynamics for the signal to symbol translator. We then describe a biologically realistic model of the olfactory system proposed by Walter Freeman that has locally stable dynamics but is globally chaotic. We show how we can discretize Freemans model using digital signal processing techniques, providing an alternative to the more conventional Runge-Kutta integration. This analysis leads to a direct mixed signal {analog amplitude/discrete time) implementation of the dynamical building block that …

A Fast Evanescent Wave Algorithm, W. C. Chew, L. (Lijun) J. Jiang, S. Velamparambil

Electrical and Computer Engineering Faculty Research & Creative Works

Description of a fast evanescent wave algorithm was presented that traded off the use of memory for increasing the speed. The use of the buffer boxes was avoided by the algorithm which increased its speed. An efficient method to derive or store the evanescent wave spectrum from the propagating wave spectrum was studied.

Computer Viruses, S. R. Subramanya, Natraj Lakshminarasmhan

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Challenge Problem Update: Peec And Mom Analysis Of A Pc Board With Long Wires Attached, H. Wang, Todd H. Hubing, Bruce Archambeault

Electrical and Computer Engineering Faculty Research & Creative Works

At the 2000 IEEE International Symposium on EMC, a paper was presented by Y. Ji et al. (paper appears in 2001 proceedings) that compared the application of PEEC and MOM techniques to the analysis of one of the EMC Society/Applied Computational Electromagnetics Society special challenge problems. Good agreement was obtained between the two codes at 2 out of the 3 measurement ports. At that time, no definite explanation was provided for the discrepancy at the third port. This paper shows that the problem was (at least partly) related to assumptions made about the signal source

Excitation And Turbine Neurocontrol With Derivative Adaptive Critics Of Multiple Generators On The Power Grid, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

Based on derivative adaptive critics, neurocontrollers for excitation and turbine control of multiple generators on the electric power grid are presented. The feedback variables are completely based on local measurements. Simulations on a three-machine power system demonstrate that the neurocontrollers are much more effective than conventional PID controllers, the automatic voltage regulators and the governors, for improving the dynamic performance and stability under small and large disturbances

Experimental Studies With Continually Online Trained Artificial Neural Network Identifiers For Multiple Turbogenerators On The Electric Power Grid, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

The increasing complexity of a modern power grid highlights the need for advanced system identification techniques for effective control of power systems. This paper provides a new method for nonlinear identification of turbogenerators in a 3-machine 6-bus power system using online trained feedforward neural networks. Each turbogenerator in the power system is equipped with a neuro-identifier, which is able to identify its particular turbogenerator and the rest of the network to which it is connected from moment to moment, based on only local measurements. Each neuro-identifier can then be used in the design of a nonlinear neurocontroller for each turbogenerator …

Impact-Ionization And Noise Characteristics Of Thin Iii-V Avalanche Photodiodes, Mohammad A. Saleh, Majeed M. Hayat, Paul P. Sotirelis, Archie L. Holmes, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

It is, by now, well known that McIntyre's localized carrier-multiplication theory cannot explain the suppression of excess noise factor observed in avalanche photodiodes (APDs) that make use of thin multiplication regions. We demonstrate that a carrier multiplication model that incorporates the effects of dead space, as developed earlier by Hayat et al. provides excellent agreement with the impact-ionization and noise characteristics of thin InP, In/sub 0.52/Al/sub 0.48/As, GaAs, and Al/sub 0.2/Ga/sub 0.8/As APDs, with multiplication regions of different widths. We outline a general technique that facilitates the calculation of ionization coefficients for carriers that have traveled a distance exceeding the …

Breakdown Voltage In Thin Iii-V Avalanche Photodiodes, Mohammad A. Saleh

Electrical and Computer Engineering Faculty Research and Publications

1. The dead-space multiplication theory of Hayat et al. [Journal of Lightwave Technology 10, 1415 (1992)], in conjunction with the multiplication-width-independent ionization-coefficient model developed by Saleh et al. [IEEE Trans. Electron Devices 47, 625 (2000)], are shown to accurately predict breakdown voltages for thin avalanche photodiodes of GaAs, InP, In_0:52Al_0:48As, and Al_0:2Ga_0:8As, over a broad range of device widths. The breakdown voltage is determined from the analytical expression for the impulse-response-function decay rate.

Sharing Health-Care Records Over The Internet, Jane Grimson, Gaye Stephens, Benjamin Jung, William Grimson, Damon Berry, Sebastien Pardon

Articles

Presents a novel approach to sharing electronic health-care records that leverages the Internet and the World Wide Web, developed as part of two European Commission-funded projects, Synapses and SynEx. The approach provides an integrated view of patient data from heterogeneous, distributed information systems and presents it to users electronically. Synapses and SynEx illustrate a generic approach in applying Internet technologies for viewing shared records, integrated with existing health computing environments. Prototypes have been validated in a variety of clinical domains and health-care settings

A Committee Of Neural Networks For Automatic Speaker Recognition (Asr) Systems, Viresh Moonasar, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes how the results of speaker verification systems can be improved and made robust with the use of a committee of neural networks for pattern recognition rather than the conventional single-network decision system. It illustrates the use of a supervised learning vector quantization neural network as the pattern classifier. Linear predictive coding and cepstral signal processing techniques are utilized to form hybrid feature parameter vectors to combat the effect of decreased recognition success with increased group size (number of speakers to be recognized)

A Novel Morphological Operator To Calculate Euler Number, Zhao Zhang, Randy Hays Moss, William V. Stoecker

Electrical and Computer Engineering Faculty Research & Creative Works

This paper introduces a novel morphological operator to calculate the Euler number for binary images. The operator is based on the condition of eight-connectedness for foreground and four-connectedness for background. It is significantly faster than the previous operators. The morphological operations used in border detection are discussed

A Parallel Computer-Go Player, Using Hdp Method, Donald C. Wunsch, Xindi Cai

Electrical and Computer Engineering Faculty Research & Creative Works

The game of Go has simple rules to learn but requires complex strategies to play well, and, the conventional tree search algorithm for computer games is not suited for Go program. Thus, the game of Go is an ideal problem domain for machine learning algorithms. This paper examines the performance of a 19x19 computer Go player, using heuristic dynamic programming (HDP) and parallel alpha-beta search. The neural network based Go player learns good Go evaluation functions and wins about 30% of the games in a test series on 19x19 board

A Continually Online Trained Neurocontroller For Excitation And Turbine Control Of A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

A Statistical Solution To A Text Decoding Challenge Problem, Xindi Cai, Rui Xu, Donald C. Wunsch, V. A. Samaranayake

Electrical and Computer Engineering Faculty Research & Creative Works

Given an encoded unknown text message in the form of a three dimensional spatial series generated by the use of four smooth nonlinear functions, we use a method based on simple statistical reasoning to pick up samples for rebuilding the four functions. The estimated functions are then used to decode the sequence. The experimental results show that our method gives a nearly perfect decoding, enabling us to submit a 100% accurate solution to the IJCNN challenge problem

Experiments On Adaptive Techniques For Host-Based Intrusion Detection, Timothy Draelos, Michael Collins, David Duggan, Edward Thomas, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

This research explores four experiments of adaptive host-based intrusion detection (ID) techniques in an attempt to develop systems that can detect novel exploits. The technique considered to have the most potential is adaptive critic designs (ACDs) because of their utilization of reinforcement learning, which allows learning exploits that are difficult to pinpoint in sensor data. Preliminary results of ID using an ACD, an Elman recurrent neural network, and a statistical anomaly detection technique demonstrate an ability to learn to distinguish between clean and exploit data. We used the Solaris Basic Security Module (BSM) as a data source and performed considerable …

Dual Heuristic Programming Excitation Neurocontrol For Generators In A Multimachine Power System, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

The design of optimal neurocontrollers that replace the conventional automatic voltage regulators for excitation control of turbogenerators in a multimachine power system is presented in this paper. The neurocontroller design is based on dual heuristic programming (DHP), a powerful adaptive critic technique. The feedback variables are completely based on local measurements from the generators. Simulations on a three-machine power system demonstrate that DHP based neurocontrol is much more effective than the conventional PID control for improving dynamic performance and stability of the power grid under small and large disturbances. This paper also shows how to design optimal multiple neurocontrollers for …

Volume Management In San Environment, Chang-Soo Kim, Gyoung-Bae Kim, Bum-Joo Shin

Electrical and Computer Engineering Faculty Research & Creative Works

Logical volume managers have long been key components of a storage system. Their key features are creation of logical or virtual views of physical storage devices and support for various software RAID levels. These make it possible to overcome the limits to capacity, availability and performance of a physical storage device. Most logical volume managers are operated in a single system environment. They are not adequate for SAN (storage area network) environments where several hosts share and access a logical volume at the same time. Some recent logical volume managers are run in a multi-host environment. However, they cannot support …

Video Compression Using Wavelets And Hierarchical Motion Estimation, Andrew Peter Byrne

Theses : Honours

This thesis investigates the benefits and the significant compression that can be obtained from data that has been decomposed using a wavelet transform. A video compression algorithm was developed that employs the wavelet transform and a hierarchical motion estimation algorithm which itself utilises benefits of the wavelet transform. Using MATLAB, a popular software tool for matrix based computation and analysis, several functions were developed which together formed the video compression algorithm. A variety of tests were conducted on a sample video sequence to ascertain the strengths and weaknesses of the techniques employed. The results, although not the same as the …

A Cable/Wireless Modulation/Demodulation Frontend Module For High Speed/Broadband Datalink, Pay Peng Clarice Chong

Theses : Honours

What are the modulation/demodulation schemes that are suitable tor cable or wireless high speed or broadband data link, between 1 Mbps to 30 Mbps? The recent adoption of modulation schemes such as OFDM, 8-VSB, OAM, for Digital Television broadcast (DTV), Asymmetrical Digital Subscriber Lines (ADSL), and Cable Modem (CM) for Internet access, is poss'1ble because of the increase bit/Hz in these modulations over conventional modulation schemes. These modulation/demodulation schemes could also offer similar advantages to dedicated data link applications such as home-networking using cable or wireless medium. This report document the project implementation of Quadrature Amplitude Modulation as the modulation …

Optical Properties Of Wide Band Gap Indium Sulphide Thin Films Obtained By Physical Vapor Deposition, N. Barreau, S. Marsillac, J. C. Bernède, T. Ben Nasrallah, S. Belgacem

Electrical & Computer Engineering Faculty Publications

Thin films of indium sulphide containing oxygen have been synthesized following a dry physical process. The constituents are deposited by thermal evaporation on glass substrates and then annealed under argon flow. Polycrystalline β-In₂S₃ containing oxygen thin films are obtained as soon as the temperature of annealing is between 623 and 723 K. In this paper, these β-In₂S₃ thin films have optically been studied. The optical band gap is direct. Its value is not dependent on the temperature of annealing. It is about 2.8 eV, which is higher than that of β-In₂S_{3 …}

Ensemble Monte Carlo Based Simulation Analysis Of Gan Hemts For High-Power Microwave Device Applications, Tao Li

Electrical & Computer Engineering Theses & Dissertations

The high electron mobility transistors (HEMTs) fabricated using wide-bandgap semiconductors show promise as high-gain, low-noise devices with superior frequency response. The structure and operation principle of HEMT are first briefly discussed. The distinguishing and unique properties of GaN are reviewed and compared with those of GaAs. Calculations of the electronic mobility and drift velocity have been carried out for bulk GaN based on a Monte Carlo approach, which serves as a validity check for the simulation model.

By taking account of polarization effects, degeneracy and interface roughness scattering, important microwave performance measures such as the dynamic range, harmonic distortion and …

An Efficient Instruction Cache Scheme For Object-Oriented Languages, Yul Chu, M. R. Ito

Electrical and Computer Engineering Faculty Publications

We present an efficient cache scheme, which can considerably reduce instruction cache misses caused by procedure call/returns. This scheme employs N-way banks and XOR mapping functions. The main function of this scheme is to place a group of instructions separated by a call instruction into a bank according to the initial and final bank selection mechanisms. After the initial bank selection mechanism selects a bank on an instruction cache miss, the final bank selection mechanism will determine the final bank for updating a cache line as a correction mechanism. These two mechanisms can guarantee that recent groups of instructions exist …

The Electrostatic Interaction Of Charged, Dust-Particle Pairs In Plasmas, M. E. Markes, P. F. Williams

Department of Electrical and Computer Engineering: Faculty Publications

We report the results of a study of the electrostatic interaction between negatively charged particles in a plasma. The goal of the study was to investigate the possibility of an attractive interaction which would make possible the formation of “molecules” of particles. For all approximations relating the positive ion density to the local electrostatic potential that we examined, we find that the interaction is repulsive for all particle separations.

Dielectric Function Of Amorphous Tantalum Oxide From The Far Infrared To The Deep Ultraviolet Spectral Region Measured By Spectroscopic Ellipsometry, Eva Franke, C. L. Trimble, M. J. Devries, John A. Woollam, Mathias Schubert, F. Frost

Department of Electrical and Computer Engineering: Faculty Publications

Amorphous tantalum oxide thin films were deposited by reactive rf magnetron sputtering onto [001] silicon substrates. Growth temperature, oxygen partial pressure, and total gas pressure have been varied to obtain thin films with different densities. The thin films were analyzed by glancing angle-of-incidence x-ray diffraction, atomic force microscopy, and variable angle-of-incidence spectroscopic ellipsometry in the near infrared to vacuum ultraviolet spectral region for photon energies from E=1 to 8.5 eV, and in the infrared region from E=0.03 to 1 eV. We present the dielectric function of amorphous tantalum oxide obtained by line shape analysis of the experimental ellipsometric …

Voltage Stability Analysis: V-Q Power Flow Simulation Versus Dynamic Simulation, Badrul H. Chowdhury, C. W. Taylor

Electrical and Computer Engineering Faculty Research & Creative Works

Several analysis methods are available for long-term voltage stability. The V-Q curve power flow method is widely used by Western Systems Coordinating Council utilities, and has some advantages. Long-term dynamic simulation with proper modeling, however, is clearly the most accurate simulation method. The authors compare the two methods for wintertime voltage stability problems in the Portland, Oregon, USA, load area. Results from the V-Q method can be misleading. The same is true of other power flow program based analysis employing conventional modeling. Results from these power flow methods may be pessimistic, causing overdesign or overly conservative operation.

A Protocol Language Approach To Generating Client-Server Software, Philip K. Chan, Melvin A.L. Douglas

Electrical Engineering and Computer Science Faculty Publications

Client-server software is becoming more common as the Internet grows. To ease the burden of repeatedly writing low-level communication and protocol code, we seek to design a protocol language, My Simple Protocol Language (MSPL), that produces the corresponding communication functions. The programmer then supplies the rest of the application-specific code but never modifies the generated code. Besides saving development time, this approach also reduces programming errors. The potential to develop more efficient code also exists once the technique of generating code is mastered. The main contribution, however, is that unlike RPC, Corba or RMI, we provide the user with not …