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2000

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Articles 211 - 240 of 282

Full-Text Articles in Electrical and Computer Engineering

Series Operation Of Direct Current Xenon Chloride Excimer Sources, Ahmed El-Habachi, Wenhui Shi, Mohamed Moselhy, Robert H. Stark, Karl H. Schoenbach Jan 2000

Series Operation Of Direct Current Xenon Chloride Excimer Sources, Ahmed El-Habachi, Wenhui Shi, Mohamed Moselhy, Robert H. Stark, Karl H. Schoenbach

Bioelectrics Publications

Stable, direct current microhollow cathode discharges in mixtures of hydrochloric acid, hydrogen, xenon, and neon have been generated in a pressure range of 200–1150 Torr. The cathode hole diameter was 250 μm. Sustaining voltages range from 180 to 250 V at current levels of up to 5 mA. The discharges are strong sources of xenon chloride excimer emission at a wavelength of 308 nm. Internal efficiencies of approximately 3% have been reached at a pressure of 1050 Torr. The spectral radiant power at this pressure was measured as 5 mW/nm at 308 nm for a 3 mA discharge. By using …

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Electroporation Dynamics In Biological Cells Subjected To Ultrafast Electrical Pulses: A Numerical Simulation Study, R. P. Joshi, K. H. Schoenbach Jan 2000

Electroporation Dynamics In Biological Cells Subjected To Ultrafast Electrical Pulses: A Numerical Simulation Study, R. P. Joshi, K. H. Schoenbach

Bioelectrics Publications

A model analysis of electroporation dynamics in biological cells has been carried out based on the Smoluchowski equation. Results of the cellular response to short, electric pulses are presented, taking account of the growth and resealing dynamics of transient aqueous pores. It is shown that the application of large voltages alone may not be sufficient to cause irreversible breakdown, if the time duration is too short. Failure to cause irreversible damage at small pulse widths could be attributed to the time inadequacy for pores to grow and expand beyond a critical threshold radius. In agreement with earlier studies, it is …

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Application Of Wavelets And Principal Component Analysis In Image Query And Mammography, Sol Neeman Ph.D. Jan 2000

Application Of Wavelets And Principal Component Analysis In Image Query And Mammography, Sol Neeman Ph.D.

Engineering Studies Faculty Publications and Creative Works

Breast cancer is currently one of the major causes of death for women in the U.S. Mammography is currently the most effective method for detection of breast cancer and early detection has proven to be an efficient tool to reduce the number of deaths. Mammography is the most demanding of all clinical imaging applications as it requires high contrast, high signal to noise ratio and resolution with minimal x-radiation. According to studies [36], 10% to 30% of women having breast cancer and undergoing mammography, have negative mammograms, i.e. are misdiagnosed. Furthermore, only 20%-40% of the women who undergo biopsy, have …

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Border Detection On Digitized Skin Tumor Images, Z. Zhang, William V. Stoecker, Randy Hays Moss Jan 2000

Border Detection On Digitized Skin Tumor Images, Z. Zhang, William V. Stoecker, Randy Hays Moss

Chemistry Faculty Research & Creative Works

A radial search technique is presented for detecting skin tumor borders in clinical dermatology images. First, it includes two rounds of radial search based on the same tumor center. The first-round search is independent, and the second-round search is knowledge-based tracking. Then a rescan with a new center is used to solve the blind-spot problem. The algorithm is tested on model images with excellent performance, and on 300 real clinical images with a satisfactory result

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Nonlinear Self-Organization In Photorefractive Materials, Partha P. Banerjee, Nickolai Kukhtarev, John O. Dimmock Jan 2000

Nonlinear Self-Organization In Photorefractive Materials, Partha P. Banerjee, Nickolai Kukhtarev, John O. Dimmock

Electrical and Computer Engineering Faculty Publications

This chapter discusses self-organization and its effects in optics. One of the most exciting and potentially useful areas of current research in optics involves the understanding and exploitation of self-organization in nonlinear optical systems. This self-organization may sometimes lead to the evolution of complex spatial patterns that can be regarded as the nonlinear eigenmodes of the system. Generation of these patterns is characteristically marked by the presence of intensity thresholds. In a nonlinear system with complicated temporal dynamics, it turns out that one cannot retain purity in spatial dimensionality. It is therefore equally important to investigate the dynamics of the …

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Dead-Time Compensators: Performance And Robustness Issues, James Syder, Thomas Heeg, Aidan O'Dwyer Jan 2000

Dead-Time Compensators: Performance And Robustness Issues, James Syder, Thomas Heeg, Aidan O'Dwyer

Conference papers

This paper will compare a number of PID and predictive controller strategies to compensate processes modelled in first order lag plus time delay (FOLPD) form. The performance and robustness of the resulting compensated systems are evaluated analytically (where appropriate) and in simulation.

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Pid Compensation Of Time Delayed Processes: A Survey, Aidan O'Dwyer Jan 2000

Pid Compensation Of Time Delayed Processes: A Survey, Aidan O'Dwyer

Conference papers

An extensive literature exists on the PID compensation of time delayed processes. It is possible to identify themes that are common to many of the available techniques. The intention of the paper is to provide a framework against which the literature may be viewed.

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Convergence Of Parameter And Delay Estimates Using Open Loop Time Domain Gradient Methods, Aidan O'Dwyer, John Ringwood Jan 2000

Convergence Of Parameter And Delay Estimates Using Open Loop Time Domain Gradient Methods, Aidan O'Dwyer, John Ringwood

Conference papers

This paper discusses the estimation of the parameters of a single input, single output (SISO) process, modelled in first order lag plus delay (FOLPD) form, using gradient methods in the open loop time domain. The paper considers the convergence of the process parameters to the model parameters. The convergence of the model delay is discussed first, when the non-delay model and process parameters are identical. The convergence of all of the model parameters is then considered, when all of the process parameters are unknown.

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Micro-Raman Study Of Stress Distribution Generated In Silicon During Proximity Rapid Thermal Diffusion, M. Nolan, T. Perova, R. A. Moore, C. J. Moore, Kevin Berwick, H. S. Gamble Jan 2000

Micro-Raman Study Of Stress Distribution Generated In Silicon During Proximity Rapid Thermal Diffusion, M. Nolan, T. Perova, R. A. Moore, C. J. Moore, Kevin Berwick, H. S. Gamble

Articles

proximity rapid thermal diffusion (RTD). A compressive stress was found on the whole silicon wafer after 15 s RTD. After 165 s RTD, the distribution of the stress across the wafer was found to be different: compressive at the edge and tensile at the middle. Thermal stress was relieved in the RTD wafers via slip dislocations. These slip dislocations were observed in the product wafers using optical microscopy. Slip lines propagated from the wafer edge to the wafer centre in eight preferred positions of maximum induced stress. The thermally induced stress and the slip dislocation density increased with time spent …

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Structural Properties And Stress Analysis Of Sio2 Thin Films, G. Joyce, C. Moore, T. S. Perova, C. Beitia, A. Kocot, Kevin Berwick, Hugh Byrne, J. M. Mcgilp Jan 2000

Structural Properties And Stress Analysis Of Sio2 Thin Films, G. Joyce, C. Moore, T. S. Perova, C. Beitia, A. Kocot, Kevin Berwick, Hugh Byrne, J. M. Mcgilp

Conference papers

Wet and dry oxidations of (111) crystalline silicon wafers were performed at temperatures between 900°C and 1150°C and subsequently annealed at 700°C. Process parameters such as the withdrawal rate from the furnace and annealing time were varied and the effect on the oxide layer are discussed. The magnitude and nature of the stress in the wafers after thermal oxidation was analysed using micro-Raman spectroscopy. The Full Width at Half Maximum (FWHM) of the Raman peak at ~ 520 cm-1 was also analysed to extract information relating to crystal disorder and defect density caused by the oxidation process. The results obtained …

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Implementations Of Bidirectional Reordering Algorithms, Steven Atkin, Ryan Stansifer Jan 2000

Implementations Of Bidirectional Reordering Algorithms, Steven Atkin, Ryan Stansifer

Electrical Engineering and Computer Science Faculty Publications

The goal of this paper is to contribute to a deeper understanding of the Unicode Bidirectional Reference Algorithm. We have provided an alternative reference algorithm written in the functional language Haskell. The advantage of Haskell is it allows for a short, clear description of a complex problem. We have run our algorithm, the two Unicode reference implementations, and four others (ICU, PGBA, FriBidi, JDK 1.2) to test for compliance with the published standard. Conclusions are difficult to reach, but problems were found in the implementations and descriptions and above all with a character-stream to character-stream interpretation of the display of …

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An Efficient Algorithm To Determine The Periodic Steady-State Solutions Of Nonlinear Systems Using Extended Spectral Analysis, Gülay Tohumoğlu Jan 2000

An Efficient Algorithm To Determine The Periodic Steady-State Solutions Of Nonlinear Systems Using Extended Spectral Analysis, Gülay Tohumoğlu

Turkish Journal of Electrical Engineering and Computer Sciences

A new method for the solution of nonlinear periodic systems was developed. It avoids the time domain calculations of the whole network equations. In the proposed method, by forming the augmented network as linear and nonlinear subnetworks these subnetworks are formulated in complex frequency and time domain respectively. Using spectral analysis the steady-state periodic solution of the whole nonlinear network is reached by an iterative approach. The method can be applied efficiently to weak and strong nonlinear circuits equally well. When we divide the network into a large linear subnetwork and a small nonlinear subnetwork, this method can be applied …

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Knowledge-Based Navigation For Autonomous Road Vehicles, Murat Eki̇nci̇, Franches W.J.Gibbs, Barry T. Thomas Jan 2000

Knowledge-Based Navigation For Autonomous Road Vehicles, Murat Eki̇nci̇, Franches W.J.Gibbs, Barry T. Thomas

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a computer vision system for an autonomous road vehicle (ARV) that is capable of negotiating complex road networks including road junctions in real time. The ultimate aim of the system is to enable the vehicle to drive automatically along a given complex road network whose geometric description is known. This computer vision system includes three main techniques which are necessary for an ARV: a) road following, b) road junction detection, c) manoeuvring at the road junction. The road following algorithm presents a method of executing a number of algorithms using different methods concurrently, fusing their outputs together …

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Decentralised H_{\Infty} Load Frequency Controller Design Based On Ssvs, Hasan Çi̇men Jan 2000

Decentralised H_{\Infty} Load Frequency Controller Design Based On Ssvs, Hasan Çi̇men

Turkish Journal of Electrical Engineering and Computer Sciences

The decentralised load-frequency controller design problem concerned is translated into an equivalent problem of decentralised controller design for a multi-area multi-input multi-output (MIMO) control system. It is shown that subject to a condition based on the structured singular values (SSVs), each local area load-frequency controller can be designed independently. The stability condition for the overall system can be stated as to achieve a sufficient interaction margin. It is demonstrated by computer simulation that within this general framework, local H$_{\infty}$ controllers can be designed to achieve satisfactory performances for a sample two-area power system.

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Information And Average Information Rates Of A Graphical Access Structure On Six Vertices, Mustafa Atici Jan 2000

Information And Average Information Rates Of A Graphical Access Structure On Six Vertices, Mustafa Atici

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper we study the optimal information and average information rates of secret sharing schemes which are all connected graphs on six vertices. There are $102$ connected graphs on six vertices that are not complete multipartite graphs. Of these $102$ graphs, we determined the optimal information rate of $71$ graphs, and the optimal average information rate of $88$ graphs.

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Comparison Of Simulation Algorithms For The Hopfield Neural Network: An Application Of Economic Dispatch, Tankut Yalçinöz, Hali̇s Altun Jan 2000

Comparison Of Simulation Algorithms For The Hopfield Neural Network: An Application Of Economic Dispatch, Tankut Yalçinöz, Hali̇s Altun

Turkish Journal of Electrical Engineering and Computer Sciences

This paper is mainly concerned with an investigation of the suitability of Hopfield neural network structures in solving the power economic dispatch problem. For Hopfield neural network applications to this problem three important questions have been answered: what the size of the power system is; how efficient the computational method; and how to handle constraints. A new mapping process is formulated and a computational method for obtaining the weights and biases is described. A few simulation algorithms used to solve the dynamic equation of the Hopfield neural network are discussed. The results are compared with those of a classical technique, …

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Radiation From An Impedance Loaded Parallel-Plate Waveguide, Fi̇li̇z Bi̇rbi̇r, Ali̇nur Büyükaksoy Jan 2000

Radiation From An Impedance Loaded Parallel-Plate Waveguide, Fi̇li̇z Bi̇rbi̇r, Ali̇nur Büyükaksoy

Turkish Journal of Electrical Engineering and Computer Sciences

A hybrid method consisting of employing the mode matching method in conjunction with the Fourier transform technique is used to analyze the radiation of the dominant TEM-wave from an impedance loaded parallel-plate waveguide. The hybrid method that we adopt here reduces the related boundary value problem to a scalar modified Wiener-Hopf equation of the second kind. The solution involves infinitely many unknown constants satisfying an infinite system of linear algebraic equations susceptible to a numerical treatment. Some computational results illustrating the effects of various parameters on the radiation phenomenon are also presented.

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A Pseudo Spot Price Algorithm Applied To The Pumped-Storage Hydraulic Unit Scheduling Problem, Sali̇h Fadil, Celal Yaşar Jan 2000

A Pseudo Spot Price Algorithm Applied To The Pumped-Storage Hydraulic Unit Scheduling Problem, Sali̇h Fadil, Celal Yaşar

Turkish Journal of Electrical Engineering and Computer Sciences

A lossy electric power system that contains thermal units and a pumped-storage hydraulic unit is considered in this paper. The total cost of thermal units in an operation cycle is minimized under some possible electric and hydraulic constraints of the units. The operation cycle is divided into time intervals where the system loads are assumed to remain constant. The proposed solution technique has two main parts. In the first part, the active thermal generations and active generation or pumping power of the pumped-storage unit in all time intervals are determined by using units' active generation incremental costs and pseudo spot …

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Distance Spectra For Trellis Coded Modulation Schemes On Channels With Intersymbol Interference, Sabi̇re Haciömeroğlu, Melek D. Yücel Jan 2000

Distance Spectra For Trellis Coded Modulation Schemes On Channels With Intersymbol Interference, Sabi̇re Haciömeroğlu, Melek D. Yücel

Turkish Journal of Electrical Engineering and Computer Sciences

The effect of intersymbol interference on distance spectra for trellis coded 8-PSK, 16-QAM and 32-AMPM modulation schemes is evaluated using the methods proposed by Schlegel. Distance spectra of 16-state 8-PSK scheme are computed for different intersymbol interference channels. It is seen that on channels with intersymbol interference the spectral lines are spread into a nearly continuous spectrum and the minimum Euclidean distance between codewords decreases severely. Hence, although the main contribution at large signal to noise ratios comes from the minimum Euclidean distance ( d_{free} ) , higher spectral components also become very important at moderate values of the signal …

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A Fuzzy Identification Method For Nonlinear Systems, İbrahi̇m Eksi̇n, Osman Kaan Erol Jan 2000

A Fuzzy Identification Method For Nonlinear Systems, İbrahi̇m Eksi̇n, Osman Kaan Erol

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, two mathematical ways of building a fuzzy model of both linear and nonlinear systems are presented and compared. In order to determine a model for a nonlinear system, the phase plane is divided into sub-regions and a linear model is assigned for each of these regions. This linear model is represented either in state-space or ARX model form. To determine the pre-selected parameters of the linear system model under study, least-square identification method is used. Then these linear models are arranged in a fuzzy manner to characterize the overall system behavior. The results show that this method …

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Control Chart Pattern Recognition Using Artificial Neural Networks, Şeref Sağiroğlu, Erkan Beşdok, Mehmet Erler Jan 2000

Control Chart Pattern Recognition Using Artificial Neural Networks, Şeref Sağiroğlu, Erkan Beşdok, Mehmet Erler

Turkish Journal of Electrical Engineering and Computer Sciences

Precise and fast control chart pattern (CCP) recognition is important for monitoring process environments to achieve appropriate control and to produce high quality products. CCPs can exhibit six types of pattern: normal, cyclic, increasing trend, decreasing trend, upward shift and downward shift. Except for normal patterns, all other patterns indicate that the process being monitored is not functioning correctly and requires adjustment. This paper describes a new type of neural network for speeding up the training process and to compare three training algorithms in terms of speed, performance and parameter complexity for CCP recognition. The networks are multilayered perceptrons trained …

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The 2-Way Thrashing-Avoidance Cache (Tac): An Efficient Instruction Cache Scheme For Object-Oriented Languages, Yul Chu, M. R. Ito Jan 2000

The 2-Way Thrashing-Avoidance Cache (Tac): An Efficient Instruction Cache Scheme For Object-Oriented Languages, Yul Chu, M. R. Ito

Electrical and Computer Engineering Faculty Publications

This paper presents a new instruction cache scheme: the TAC (Thrashing-Avoidance Cache). A 2-way TAC scheme employs 2-way banks and XOR mapping functions. The main function of the TAC is to place a group of instructions separated by a call instruction into a bank according to the Bank Selection Logic (BSL) and Bank-originated Pseudo-LRU replacement policies (BoPLRU). After the BSL initially selects a bank on an instruction cache miss, the BoPLRU 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 in each bank safely. …

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Successful Proposal Preparation, Mariesa Crow Jan 2000

Successful Proposal Preparation, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

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About Resonant Modes At The Shielded Dielectric Hemisphere, Sergey Kharkovsky, A. E. Kogut, Z. E. Eremenko, V. V. Kutuzov, Yuri F. Filipov Jan 2000

About Resonant Modes At The Shielded Dielectric Hemisphere, Sergey Kharkovsky, A. E. Kogut, Z. E. Eremenko, V. V. Kutuzov, Yuri F. Filipov

Electrical and Computer Engineering Faculty Research & Creative Works

The resonant modes, which are excited at the shielded dielectric hemisphere, are investigated by the theoretical and experimental methods. The low-Q-factor modes of air cavity and high-Q-factor whispering gallery modes of dielectric structure are existed together in the case of high radial index value. The Q-factor value of the whispering gallery modes of the shielded dielectric sphere with the certain correlation between the sizes of dielectric hemisphere and metal shield can be more great than the Q-factor of the whispering gallery modes of the similar open dielectric resonator.

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A Hysteresis Current-Regulated Control For Multi-Level Drives, Keith Corzine Jan 2000

A Hysteresis Current-Regulated Control For Multi-Level Drives, Keith Corzine

Electrical and Computer Engineering Faculty Research & Creative Works

Most multi-level converters are controlled through the use of voltage-source based control techniques such as space-vector modulation or multi-level sine-triangle modulation. However, in many applications such as field oriented drives, a high bandwidth current-source inverter based control is more desirable. In this paper, the concept of a multi-level hysteresis current-source control is set forth. The new control is experimentally verified using a four-level converter/induction motor drive system and the results are compared to a space vector modulation controller. A dynamic study involving a step change in current command demonstrates the controls high bandwidth.

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A Robust Proportionate Affine Projection Algorithm For Network Echo Cancellation, T. Gansler, J. Benesty, Steven L. Grant, M. M. Sondhi Jan 2000

A Robust Proportionate Affine Projection Algorithm For Network Echo Cancellation, T. Gansler, J. Benesty, Steven L. Grant, M. M. Sondhi

Electrical and Computer Engineering Faculty Research & Creative Works

Echo cancelers which cover longer impulse responses (greater than or equal to 64 ms) are desirable. Long responses create a need for more rapidly converging algorithms in order to meet the specifications for network echo cancelers devised by the ITU (International Telecommunication Union). In general, faster convergence implies a higher sensitivity to near-end disturbances, especially "double-talk." Previously, a fast converging algorithm called the proportionate NLMS (normalized least mean squares) algorithm (PNLMS) has been proposed. This algorithm exploits the sparseness of the echo path in order to increase the convergence rate. A robust version of PNLMS has also been presented which …

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A Schooling On Their Implications For Software Engineering [Trends], Ann K. Miller Jan 2000

A Schooling On Their Implications For Software Engineering [Trends], Ann K. Miller

Electrical and Computer Engineering Faculty Research & Creative Works

A discussion is presented on trends in software engineering. This can be done by simply extrapolating some of the popular, current trends. And, in fact, we examine a few of these obvious indicators. However, software engineering has had new approaches that are more revolutionary than evolutionary. In particular, we try to discern trends in software engineering based on trends in delivered software systems.

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Adaptive Critic Based Neurocontroller For Turbogenerators With Global Dual Heuristic Programming, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley Jan 2000

Adaptive Critic Based Neurocontroller For Turbogenerators With Global Dual Heuristic Programming, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

Turbogenerators are nonlinear time varying systems. This paper presents the design of a neurocontroller for such a turbogenerator that augments/replaces the traditional automatic voltage regulator (AVR) and the turbine governor using a novel technique based on the adaptive critic designs (ACDs) with emphasis on global dual heuristic programming (GDHP). Simulation results are presented to show that the neurocontroller derived with the GDHP approach is robust and its performance is better when compared with that derived with other neural network technique, especially when system conditions and configuration changes.

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Advances Of Gyromagnetic Electronics For Emc Problems, Marina Koledintseva, L. K. Mikhailovsky, Alexander A. Kitaytsev Jan 2000

Advances Of Gyromagnetic Electronics For Emc Problems, Marina Koledintseva, L. K. Mikhailovsky, Alexander A. Kitaytsev

Electrical and Computer Engineering Faculty Research & Creative Works

A number of EMC problems at microwaves-detection and measurement of power (spectrum) of the signals and suppression of unwanted radiation-can be solved owing to the results obtained in the field of gyromagnetic (spin) electronics. The latter deals with the unique properties of gyromagnetic media (GM) based on microwave ferrites, including high-anisotropy hexagonal ferrites that do not need an intense magnetization field for their operation at ferromagnetic resonance. Approaches to the study of the interaction of GM with an electromagnetic field and ways of modeling frequency-selective measuring devices, absorbing coatings and all-mode filters of harmonics on the basis of GM are …

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Analysis Of A Novel Four-Level Dc/Dc Boost Converter, Keith Corzine, Sonal K. Majeethia Jan 2000

Analysis Of A Novel Four-Level Dc/Dc Boost Converter, Keith Corzine, Sonal K. Majeethia

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, novel two-quadrant buck/boost and one-quadrant boost four-level DC/DC power converters are introduced. The primary application for these converters is that of interfacing a low-voltage DC source, such as a fuel cell or battery, to a high-voltage four-level inverter. One important feature of the four-level DC/DC power converters proposed is the ability to perform the power conversion and balance the inverter capacitor voltages simultaneously. With the capacitor voltage balancing, it is possible to obtain the full voltage from the inverter. For the boost converter, the steady-state and nonlinear average-value (NLAM) models are developed. The NLAM is verified against …

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