Engineering Commons^™

Scattering From Finite By Infinite Periodic Arrays With Arbitrary Piecewise-Linear Slot Elements, Paul R. Barre

Theses and Dissertations

A numerical model for analyzing electromagnetic scattering from a planar Frequency Selective Surface (FSS) is developed. The model can represent an FSS with multiple arrays of arbitrary piecewise linear scatterers in a stratified dielectric medium. The FSS's arrays are finite by infinite, accounting for edge effects, where a periodic array element is formed from the piecewise linear connection of thin slots in a groundplane. The stratified dielectric medium is defined as an arbitrary stack of lossless dielectric slabs that sandwich the user defined arrays, simulating an FSS. The Surface Equivalence theorem is used to construct an equivalent problem based on …

Optimal Mixed-Norm Control Synthesis For Discrete-Time Linear Systems, David R. Jacques

Theses and Dissertations

A mixed-norm approach to control synthesis for discrete time linear systems is developed. Specifically, the problem of minimizing the H₂ norm of a transfer function, subject to a combination of ℓ₁ and-or H_∞ norm constraints on dissimilar but related transfer functions is considered. The uniqueness of the optimal solution is shown, and numerical methods for approximating the optimal solution to within arbitrary accuracy are developed. These methods generally result in high order compensators which can not be implemented in most practical applications. In response to this, a numerical method is developed which solves for suboptimal solutions of …

Grain-Size Optimization And Scheduling For Distributed Memory Architectures, Jing-Chiou Liou

Dissertations

The problem of scheduling parallel programs for execution on distributed memory parallel architectures has become the subject of intense research in recent, years. Because of the high inter-processor communication overhead in existing parallel machines, a crucial step in scheduling is task clustering, the process of coalescing heavily communicating fine grain tasks into coarser ones in order to reduce the communication overhead so that the overall execution time is minimized.

The thesis of this research is that the task of exposing the parallelism in a given application should be left to the algorithm designer. On the other hand, the task of …

Investigation Of Hybrid Message-Passing And Shared-Memory Architectures For Parallel Computer : A Case Study : Turbonet, Xi Li

Dissertations

Several DSP (Digital Signal Processing) algorithms are developed for the MIT TurboNet parallel computer. In contrast to other parallel computers that implement exclusively in hardware either the message-passing or the shared-memory communication paradigm, or employ distributed shared-memory architectures characterized by inefficient implementation of the shared-memory paradigm, the hybrid architecture of TurboNet supports direct, efficient implementation of both paradigms. Three versions of each algorithm are developed, if possible, corresponding to message-passing, shared-memory, and hybrid communications, respectively. Theoretical and experimental comparisons of algorithms are employed in the analysis of performance. The results prove that the hybrid versions generally achieve better performance than …

Radiation Damage Studies In Gate Oxides, Sandeep G. Bharathi

Theses

Detailed investigation of the effects of Gamma-ray irradiation on the electrical properties such as current-voltage arid capacitance-voltage characteristics in thermally grown SiO₂ films in the thickness range of 15 to 120 nm on silicon substrates is presented in this thesis. The structures used in this study are Al/Poly/SiO₂/Si/Al and Al/SiO₂/Si/Al MOS capacitors. Based on the electrical characterization studies, we observe that irradiation causes generation of positive charges in the oxide leading to a shift of the high frequency Capacitance-Voltage (C-V) curves. An increase in surface state density at the SiO₂-Si interface with increase …

A Modified Lrt-Based Spread-Spectrum Receiver Using Spatial And Temporal Processing, Jeffrey L. Cutcher

Theses

The problem of demodulating a direct-sequence (DS) spread-spectrum signal in the presence of single-tone or narrow-band interference and multi-path is discussed. A likelihood-ratio test (LRT) receiver is presented which consists of a whitening filter and a RAKE correlator.

A modified LRT receiver structure is then considered where the whitening filter is replaced by an antenna array with corresponding tap coefficients. The array spatially removes the interference by estimating it's angle-of-arrival. Using the array has an advantage over the original LRT receiver when a narrow-band interference is present. Both receivers are identical in performance under the single-tone interference model.

A third …

A Defect Detection Algorithm For Sequential And Parallel Computers, Ralf Hross

Theses

The comparison of images containing a single object of interest, where one of them contains a model object, is frequently used for defect detection/identification. This is often a problem of interest to industrial applications. To make this task more efficient, the implementation on parallel computers should be a major objective. This thesis introduces sequential and parallel versions of an algorithm that compares original(reference) and processed images in the time and frequency domains. The emphasis is on parallel implementation. This comparison may help to detect changes in images. Extracted data is also compared to database data in an attempt to pinpoint …

Laser Scanning In-Situ Photoelectrochemical Microscopictechnique And Its Applications, Zugeng Lin, Jinkua You, Xiangdong Zhuo, Chun Zhang, Yong Yang

Journal of Electrochemistry

The main factors of the laser scanning in-situ photoelectrochemical microscopic measurement system which is set up in our lab have been discusaed in this paper. Some applications of this technique for in-situ study of modification and processing of semiconductor electrodes, monitoring of electro deposition process of semiconducting material and redox reaction occurring at metal oxide electrodes have also been presented. The results have shown that the technique is very powerful that for studing local photoelectrochemical properties of semiconductors and metal oxide electrodes. These provide important information on the micro structural and electronic properties in the solid/electrolyte interface.

Studies On Low Temperature Performance Of Rechargeable Mh-Ni Batteries, Wenkuan Zhang, Jingxian Shi, Yuwan Lou, Qiusheng Duan

Journal of Electrochemistry

The Dependence of low temperature performance on the alloy composition and electrolyte component for rechargeable MH-Ni batteries is studied, the suitable composition of alloy and electrofyte are founds.

An Indirect Electrochemical Oxidation Of Toluene──Anodic Oxidation Of Mn(Ⅱ) On The Lead Electrode, Zhonghua Wang, Qingmin Hua, Guacai Chen, Zhongquan Wang, Yunan Qiu, Xingguo Yan

Journal of Electrochemistry

The electrochemical oxidation of Mn(Ⅱ) to Mn(Ⅱ) in concentrated H₂SO₄ (2 ~ 8 mol⋅L^-1) at lead electrode has been studied. It is found that the electrode surface is oxidized to PbO₂ in a direct electrochemical reaction, then PbO₂ formed reacts with Mn(Ⅱ) in a chemical reaction. Some effects involves current density, concentration of H₂SO₄, temperature and conversionwere evaluated. The rule of electrogenerated Mn(Ⅲ) in flow electrolysis cell were determined at several conditions. The current efficiency at greater than 90% is obtained in general.

Electrochemically Modified Glassy Carbon Electrode And Determination Of Copper By Anodic Stripping Voltammetry, Jinrui Xu, Yie Liu, Xiurun Zhuang, Tomoo Miwa, Toyohide Takeuchi

Journal of Electrochemistry

This paper reported the glassy carbon electrode modified by cyclic voltammetrybetween -0.1 and +1.5 V (vs. SCE) in an aqueous solution containing catechol, for maldehyde and talium hydroxide. The modified electrode can be applied to the determination of copper(Ⅱ) in water, and its sensitivity is about 35 times higher than that of unmedified glassy carbon electrode, The quantitative limit with this modified electrode is 0.1 ng/ml.

The Electrochemical Reduction Of 2-Ethylanthraquinone (2eaq), Yaobin Zhu

Journal of Electrochemistry

The process of electrochemical reduction of 2EAQ in DMSO is studied using CVand ESR methods in this work, Pt, Pd and some implanted materials are used as electrodes. The quasi-rever-sible property of two electron transfer steps and their following homogeneous chemical reactions are illustrated. The mechanism of the electrochemical red uction of 2EAQ and the kinetic parameters of the related steps are obtained. Having measured the influence of water content in the system, the effect of the proton donor is discussed. After comparising the experimental results with each other these experiments gives us the idea that the replacement of metal …

Photoelectrochemical And Spectroelectrochemical Studies Oniron Oxide Ultrafine Particles, Maizhi Yang, Yongjun Ji, Wen Zhang, Shengmin Cai, Xiaojiang Lu, Zhongqun Tian, Jin Luo

Journal of Electrochemistry

In this paper, Raman spectra, photocurrent and the UV-VIS reflectance aremeasured for studying the α-Fe₂O₃ ultrafine particles adsorbed on Pt electrode. The blue shifts of Raman peaks demonstrate the size quantization effect for the particles of 50 nm in diameter ascompared with the bulk material. With the changing of the potential, the photocurrent decrcases as the UV-VIS reflectance increases, and vice-versa. Therefore, the potential not only affects the hargetransfer direcdtion in the interface of electrode/redox couple, but also influences the light absortion onthe surface of particles. According to the results of photoelectrochemistry, we suggest that the cathodic …

Horseradish Peroxidase/Poly-O-Phen Ylenediamine Mem Brane Electrode: Preparation And Properties, Dong Wei, Huihuang Wu

Journal of Electrochemistry

A horseradish peroxidase (HRP)/poly-o-phenylenediamine (PPD) membrane electrode was prepared by electropolymerization of o-phenylenediamine on glassy carbon in pH 7.0 phosphate buffer, the process of the enzyme immobilization was studied. The enzyme electrode obtained exhibits the activity to catalyze the electroreduction of hydrogen peroxide in the absence of any electron transfer mediator. The red uction reaction occurs in the potential range of PPD redoxprocess, it was believed that the polymer participates in electron transfer of the enzyme. The enzyme reaction kinetics at rotating HRP/PPD electrode was analysed, and the factors influencing kinetic parameters were discussed.

The Reduction Of Oxygen To Hydrogen Peroxide At The Poly(O-Phenylenediamine)-Filmed Electrode, Zhaoe Lu, Tiangeng Zhong, Guanyong Zhang

Journal of Electrochemistry

The poly(o-phenylenediamine) (PPD) filmed graphite electrode was formed by electro-polymerization of o-phenylenediamine in acidified (pH=1) 0.2 mol·L^-1 Na₂SO₄ solution using the cyclic voltammetric methed. The catalytic effect of the electrcareduction of oxygen in acid olution was demonstrated by the voltammogram of the electrode in the oxygen saturated acid solutionof Na₂SO₄. The current efficiency of the reduction of oxygen to hydrogen peroxide was determined by the electrolysis in a divided cell under the condition of constant current. The various effectsinfluencing the accmulation of H₂O₂ in the catholyte were discussed.

Studies On Coordination Behavior Of Dimethyl Sulfoxide In Complex Of Rare Earth With Cryptand, Shichang Liu, Tianpei Zhu

Journal of Electrochemistry

Electrochemical reduction reaction in the course of the titration of Eu(2.2.2) and Eu(2.2) using strong bonding solvent, DMSO, in C₂H₄Cl₂ has been investigated by cyclic voltammetry. The greater the concentration of strong bonding solvent, the more negative the half-wave potentials for the reduction reaction are. The coordination number of Eu(2.2.2) and Eu(2.2) which are 2 and 3 respectively, with DMSO can be calculated, according to the relations between half-wave potentials and the variety of concentration of DMSO.

Effects Of Hydrogen On Inp Light-Emitting Devices Etched In A Methane-Hydrogen Environment, Patricia Beck, Dennis J. Derickson, Forrest Kellert, Tim Bagwell

Electrical Engineering

Research has been conducted on the physical damage and hydrogenation effects during RF plasma exposure and epitaxial growth in the III-V material system. Device consequences of this damage or chemical alteration have received less attention, particularly in active light emitting devices. This paper discusses these effects for lasers and edge emitting light-emitting diodes (EELEDs) which use a ridge waveguide structure. By using analysis techniques such as SIMS we have concluded that methane-hydrogen reactive ion etching of InP induces hydrogen levels in an active device which are high enough to significantly alter the device properties. The decrease in light output is …

A Vhdl Design Of A Reconfigurable Cache Memory System, Tiffany M. Brooks

Honors Capstone Projects and Theses

No abstract provided.

Bandwidth And Additive Bandwidth Of Graphs, Maria Kujawski

Honors Capstone Projects and Theses

No abstract provided.

Testability Design And Testability Analysis Of A Cube Calculus Machine, Lixin Zhou

Dissertations and Theses

Cube Calculus is an algebraic model popular used to process and minimize Boolean functions. Cube Calculus operations are widely used in logic optimization, logic synthesis, computer image processing and recognition, machine learning, and other newly developing applications which require massive logic operations. Cube calculus operations can be implemented on conventional general-purpose computers by using the appropriate "model" and software which manipulates this model. The price that we pay for this software based approach is severe speed degradation which has made the implementation of several high-level formal systems impractical. A cube calculus machine which has a special data path designed to …

Fuzzy Logic For Digital Phase-Locked Loop Filter Design, Daniel J. Simon, Hossny El-Sherief

Electrical and Computer Engineering Faculty Publications

The problem of robust phase-locked loop design has attracted attention for many years, particularly since the advent of the global positioning system. This paper proposes and demonstrates the use of a fuzzy PLL to estimate the time-varying phase of a sinusoidal signal. It is shown via simulation results that fuzzy PLL's offer performance comparable to analytically derived PLL's (e.g. Kalman filters and H_∞ estimators) when the phase exhibits high dynamics and high noise. The fuzzy PLL rules are optimized using a gradient descent method and a genetic algorithm

Identification And Evaluation Of Monitoring Techniques For The Performance Of A Communication Network, Maureen E. Borgia

Theses and Dissertations

This study investigates the application of statistical process control methods to monitoring the performance of a communication network. The methods applied include four different types of control charts. The literature search uncovered only one previous study that used a control chart to monitor a communication network. Using a case study of a communication network, four important issues for proper control chart usage are emphasized. These issues are: proper data collection rate due to autocorrelation, proper subgrouping of the data, ensuring that count data conforms to the assumptions of the binomial probability model before implementing p or np control charts, and …

Power Bus Decoupling On Multilayer Printed Circuit Boards, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, David M. Hockanson

Electrical and Computer Engineering Faculty Research & Creative Works

Guidelines for the selection and placement of decoupling capacitors that work well for one-sided or two-sided printed circuit boards are not appropriate for multilayer boards with power and ground planes. Boards without internal planes take advantage of the power bus inductance to help decouple components at the higher frequencies. An effective decoupling strategy for multilayer boards must account for the low inductance and relatively high capacitance of the power bus.

Determination Of Alas Optical Constants By Variable Angle Spectroscopic Ellipsometry And A Multisample Analysis, C. M. Herzinger, H. Yao, Paul G. Snyder, F. G. Celii, Y. C. Kao, B. Johs, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Using variable angle spectroscopic ellipsometry, optical constants for AlAs (1.4-5.0 eV) are presented which are simultaneously compatible with measured data from four different samples. The below-gap index values are compatible with published prism measured values. The second derivative spectrum are compatible with published values above the direct band gap. The AlAs spectra is Kramers-Kronig self-consistent over the measured range and is compatible with published values from 0.6 to 1.4 eV. The optical constants for thin (<50 >Å) GaAs caps on AlAs are shown to be different from bulk GaAs values and require special consideration when fitting ellipsometric data. For the …

Navigation Satellite Selection Using Neural Networks, Daniel J. Simon, Hossny El-Sherief

Electrical and Computer Engineering Faculty Publications

The application of neural networks to optimal satellite subset selection for navigation use is discussed. The methods presented in this paper are general enough to be applicable regardless of how many satellite signals are being processed by the receiver. The optimal satellite subset is chosen by minimizing a quantity known as Geometric Dilution of Precision (GDOP), which is given by the trace of the inverse of the measurement matrix. An artificial neural network learns the functional relationships between the entries of a measurement matrix and the eigenvalues of its inverse, and thus generates GDOP without inverting a matrix. Simulation results …

On Primitive Bch Codes With Unequal Error Protection Capabilities, Robert H. Morelos-Zaragoza, Shu Lin

Faculty Publications

Presents a class of binary primitive BCH codes that have unequal-error-protection (UEP) capabilities. The authors use a previous result on the span of their minimum weight vectors to show that binary primitive BCH codes, containing second-order punctured Reed-Muller (RM) codes of the same minimum distance, are binary-cyclic UEP codes. The values of the error correction levels for this class of binary LUEP codes are estimated.

An Adaptive "Natural Law" Fuzzy Controller, Sandeep D. Sequeira

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Fuzzy control has met with a tremendous interest in applications over the past few years. Despite its application potential, a broader industrial exploitation of fuzzy control has been hindered by the lack of standard design methods for fuzzy control systems. Fuzzy controllers have had to be designed on a case-by-case basis employing heuristics and reflecting the designer's limited insight into the control object's behavior. A number of fuzzy theorists have investigated the fuzzy system theoretic problems and results reported in the literature have been encouraging.

This thesis research has explored the notion that fuzzy control, despite being a rule-based control …

Techniques To Improve Electron Density Measurements In The D Region Of The Ionosphere, Earl F. Pound

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The electron density of the ionosphere can be measured using rocket-borne probes that measure changes of the impedance of an antenna as it traverses the plasma. The resistive component of the antenna impedance is difficult to measure accurately in the D region of the ionosphere (50-90 km) because it has such a small value and is in series with a much larger capacitive reactance. The resistance term is squared during data analysis and this further adds to the inaccuracy. Previous data analysis has usually ignored the resistive term and led to errors of as much as 35% for the altitude …

Visible Light Emitting Diodes Fabricated From Soluble Semiconducting Polymers, Alan J. Heeger, David Braun

Electrical Engineering

Visible light LEDs are produced having a layer of conjugated polymer which is cast directly from solution or formed as a gel-processed admixture with a carrier polymer. The LEDs can be formed so as to emit polarized light.

Effects Of Varying Coupling Impedance, Finite Length, And Asynchronous Harmonics On High Power Bwo Performance, Larald Dean Moreland

Electrical and Computer Engineering ETDs

A systematic study of high power backward wave oscillators (BWOs) was performed using the Sinus-6 repetitively-pulsed relativistic electron beam accelerator. Peak output power of up to 550 MW was measured in a frequency range of 9.2 to 9.8 GHz with pulse lengths up to 10 ns. The experimental results were compared with numerical simulations using TWOQUICK, a 2.5 D, relativistic, fully electromagnetic, particle-in-cell (PIC) code. It was observed that a significant increase in microwave efficiency can be obtained by using a BWO with a spatially varying coupling impedance instead of the traditional uniform distribution. Based on experiments using variations of …