Engineering Commons^™

Nonlinear, Metal-Clad Optical Waveguide, Bhavesh Patel

Theses

Planar optical waveguides consisting of different types of films including nonlinear films with metal cladding have been studied theoretically. Ideal metal cladding with σ = ∞ and nonideal metal cladding with σ ≠ ∞, that is, with complex refractive index is considered to get electric field and wave number for TE₀ mode. For nonlinear material, approximate solution is derived in a series form using Rayleigh-Schrodinger method. The appropriate eigenvalue equations are solved by Newton-Raphson iteration method. For self-focusing media in the center, the propagation constant increases with increasing power and with self-focusing media in the cladding the propagation constant …

Study Of Ionized Cluster Beam Techniques For Reactive Deposition Of Gallium Nitride Thin Films, Jyh Sheen

Theses

This thesis is divided into two parts. The first part investigates the Ionized Cluster Beam( ICB ) technique through measurements of the energy of ionized gallium beam. The presence of ions and their kinetic energy in the ICB technique is advantageous in the formation process of thin film. The results of retarding potential measurement are comparable with the presence of clusters as large as 500 atoms. The second part examines the formation of gallium nitride thin film. In order to enhance the reaction of gallium and nitrogen, dissociation of molecular nitrogen by microwave discharge method was used to generate atomic …

Firmware Toolkit For Larynx Synchronous D.S.P., Shih-Chieh Su

Theses

During the past ten years, digital signal processing has been an extremely active and dynamic field. Advances in integrated circuit technology and in processor architecture have greatly enlarged the scope of the technical areas to which digital signal processing techniques can be applied. Research in fundamental signal processing techniques and algorithms has led to dramatic improvements in the efficiency of signal processing systems.

This thesis creates a fast and cheap DSP package for 8052AH-BASIC. This is a useful and potential package when we apply research in speech science and medical diagnostics. It exploits the latest software-in-silicon technology to create a …

Electrical Insulation Screening For Reliability, Vinu Sundaresan

Theses

This thesis work includes an investigation on the use of electrical noise for the screening of dielectric sheet material for reliability. Three different high voltage insulation sheet materials, commonly used in power industry, have been studied. These are - Westinghouse Polyester resin coated glass cloth, Dupont ‘NOMEX' aramid calendared paper and a cotton rag commonly known as Fishpaper. Samples of each material have been categorized into low noise and high noise units. Subsequently, these samples were subjected to accelerated life testing.

It is seen that units having high noise are failing quicker compared to low noise units when subjected to …

Design Of Governor-Turbine Models In Stability Studies, Vidyanand Swaminathan

Theses

This thesis investigates the effect of hydro governor-turbine models on the steady state stability of an automatically controlled electric power system. Basically two kinds of hydro governor-turbine models, namely, Impulse and Francis type are studied in depth. Design of a compensating network has also been proposed, which can help improve the stability conditions of a power system which employs a poor governor-turbine model.

The power system investigated includes a large sized hydro generating unit connected to an infinite bus via a power network. This generator employs a modern three-channel fast-acting automatic voltage regulator (AVR). For any operating condition, stability results …

Spectrum Analysis Of Heart Rate Variability, Xuming Wang

Theses

This research investigated the respiratory influence on heart rate variability. The heart rate spectrum was obtained from the heart rate variability signal which was extracted from the electrocardiogram We then studied the magnitude of the respiration peak in the heart rate spectrum and examined the dependence of the magnitude of this peak on breathing frequency, subject and day.

An experiment designed to simultaneously acquire the electrocardiogram and the respiration signal was conducted on ten people ranging from 22 to 55 years of age (3 females, 7 males). Three tests were performed on each subject. In each test, 2 different postures …

Efficient Design Of Trellis Coded Cpfsk, Hsinhsyong Yang

Theses

In this thesis convolutional coded continuous-phase frequency shift keying (CPFSK) is studied.

CPFSK which is a subclass of continuous phase modulation ( CPM ) is a constant amplitude digital modulation scheme with very good spectral characteristics.

A new method, called matched encoding, that combines convolutional codes and CPFSK is studied. With the maximum free Euclidean distance as the optimization criterion, the best combined coded schemes were found for the same rate of the codes and given total number of states in the optimum decoder.

A different method which was suggested by Rimoldi[7], called the decomposition method, is also described in …

Rays And Beams Near The Shadow Boundary, Weixing Gao

Theses

Asymptotic techniques in wave propagation problems exhibit attractive features in computational aspects compared to numerical methods. However, they experience problems in complicated environments due to the transition regions associated with them. The transition region involving a shadow boundary in the downward refractive index profile has been investigated. The ray paths were determined solving the ray equation analytically. The Green's function due to a line source is constructed and evaluated using numerical integration (reference solution) and asymptotic techniques. Then, the field produced by the source, is synthesized, using superposition of beams generated from complex source point representation. The floating parameters such …

The Application Of The Ordered List Method And The Dynamic Programming To The Unit Commitment, Hoang Uong

Dissertations and Theses

The thesis presents a method of committing generating units in a hydro-thermal power system within practical computer resources such as computer time and data storage.

Radio-Frequency Plasma Chemical Vapor Deposition Growth Of Diamond, Duane E. Meyer, Rodney O. Dillon, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Plasma chemical vapor deposition (CVD) at 13.56 MHz has been used to produce diamond particles in two different inductively coupled systems with a mixture of methane and hydrogen. The effect of a diamond-like carbon (DLC) overcoating on silicon, niobium, and stainless-steel substrates has been investigated and in the case of silicon has been found to enhance particle formation as compared to uncoated polished silicon. In addition the use of carbon monoxide in hydrogen has been found to produce well-defined individual faceted particles as well as polycrystalline films on quartz and DLC coated silicon substrates. Plasma CVD is a competitive approach …

An Evaluation Of The Plasma Frequency Probe, Charles Merrill Swenson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Electron density in a plasma can be measured by determining the plasma frequency. For 20 years this electron density measurement technique has been used with the plasma frequency probe. The purpose of this paper is to characterize, evaluate, and suggest improvements for this instrument. Although the current plasma frequency probe is a highly successful instrument for measuring absolute electron density in the ionosphere, several areas for improvement were found. These were in the radio frequency head and the voltage controlled oscillator. Currently, the plasma frequency probe is approximately 20% accurate in determining absolute densities around 1.5x10⁴ electrons/cm³ but …

Convergence Properties Of The Waveform Relaxation Method As Applied To Electric Power Systems, Marija D. Ilić, J. K. White, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Several theoretical results are presented and simple examples examined in order to determine the suitability of waveform relaxation for transient power system simulation. This examination leads to two practical suggestions that can easily be satisfied for power systems. The first is to break the simulation interval into sections, the first of which should be narrow and be used to kill off errors in the initial guess that activate the stiff modes. The second is to partition the system into subsystems that are stable, as this not only aids convergence but ensures multirate numerical stability.

Microprocessor Based Protection Of Induction Motors Using Thermal, Mechanical, And Skin Effect Electrical Models To Predict Motor Temperature Rise, Nader S. Moharari

Masters Theses and Doctoral Dissertations

This study investigates induction motor performance during a variety of system and load conditions. A computer simulation is used to characterize the motor behavior during normal operation, lockedrotor case, high inertia loading, and overloading conditions. Motor temperature at critical points is estimated. A microprocessor protection scheme based on motor temperature is proposed. Previous studies assume a linear relationship between motor impedance and frequency when calculating motor temperature. In this study an electrical model, based on Maxwell's equations, is used in conjunction with a mechanical model, to represent the motor during dynamic state conditions. The model accounts for the rotor bar …

Optical- And Magnets-Optical Measurements Using A Variable Angle Of Incidence Spectroscopic Ellipsometer: Application To Dyco Multilayer, William A. Mcgahan, Z. S. Shan, Alan M. Massengale, Thomas E. Tiwald

Department of Electrical and Computer Engineering: Faculty Publications

We have extended the technique of variable angle spectroscopic ellipsometry to measurement of the magneto-optical effects as a function of wavelength and angle of incidence and field strength. Results on DyCo multilayers are reported.

Direct Current-Excited Cw Co² Metal Waveguide Laser, Fahad S. Al-Mashaabi, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

A novel design for a dc-excited cw CO₂ metal waveguide laser has been developed in which a slotted hollow cathode also doubles as a metal waveguide for the cavity modes. This design has been implemented in a compact structure that produces over 1 W of cw 10.6-µm radiation. The discharge characteristics, laser gain, and laser output have been studied as functions of various discharge parameters. The advantages of the transverse discharge of the slotted hollow cathode geometry include low voltage, positive impedance, rugged structure, and high optical gain. Overall efficiency is comparable with that of conventional longitudinal CO² lasers. The …

Discovery Of Strong Coupling Between Lattice-Band Carriers And Impurity-Band Carriers In Augmented Photoconductivity Measurements On Si:As, Si:Bi, And Si:Al At 7-16 K, James Edward Heath

Electrical and Computer Engineering ETDs

In this work, low-temperature photoconductivity measurements using excitation in the long-wavelength infrared were performed in conjunction with infrared-blocked band-gap excitation in the first studies of the energy transfer between carriers moving in lattice bands and those associated with an impurity band in a semiconductor. Extrinsic (impurity-band) excitations were produced in Si:As, Si:Bi, and Si:Al detectors by infrared photoexcitation at 29-33.5 μm wavelengths (37-43 meV); this could be augmented by simultaneous intrinsic (band-gap) photoexcitation using infrared-blocked white light to inject lattice-band carriers. Carrier transport was induced by applied electric fields of 35-175 V /cm. The experiments were performed at temperatures of …

A Finite State Machine Synthesizer, Jiuling Liu

Dissertations and Theses

This thesis presents a Finite State Machine (FSM) Synthesizer developed at Portland State University. The synthesizer starts from a high level behavioral description, in which no states are specified, and generates the lower level FSM descriptions for simulation and physical layout generation.

Optical-Absorption Edge And Disorder Effects In Hydrogenated Amorphous Diamondlike Carbon Films, T. Datta, John A. Woollam, W. Notohamiprodjo

Department of Electrical and Computer Engineering: Faculty Publications

Optical absorption (~1–5 eV) in rf-deposited hydrogenated (20–40 at. %) amorphous “diamondlike” carbon films has been studied as a function of heat treatment. For E >~ 2.5 eV a Tauc behavior is exhibited. Optical band gaps E_g are E₀, the width of the tail, is quantitatively explained in terms of the annealing temperature T_H. Increasing T_H (<700 >K) reduces the hydrogen content, lowers E_g, and appears to harden the films. E_g is determined to be a linear function of E₀. Additional analysis was performed in terms of a divergence …

Maximum Rate Of Change Of The Differential Reflection Phase Shift With Respect To The Angle Of Incidence For Light Reflection At The Surface Of An Absorbing Medium, R. M.A. Azzam, A. M. El-Saba

Electrical Engineering Faculty Publications

The differential reflection phase shift, Δ = δ_p - δ_s, associated with the external reflection of monochromatic light at the surface of an absorbing medium is a monotonically decreasing function of the angle of incidence ø which is determined by the complex dielectric function ε. A new special angle of incidence, denoted by ø_Δ′max, is defined at which the slope Δ′ = ∂Δ/∂ø of the Δ-ø curve is maximum negative, Δ′_max, and a transcendental equation is derived that determines this angle. ø_Δ′max differs from the principal angle ø_p at which Δ …

Efficient Multi-Layer Channel Routing, Ronald I. Greenberg

Computer Science: Faculty Publications and Other Works

No abstract provided.

Performance Modeling And Enhancement For The Atamm Data Flow Architecture, Sukhamoy Som

Electrical & Computer Engineering Theses & Dissertations

Algorithm To Architecture Mapping Model (ATAMM) is a new marked graph model from which the rules for data and control flow in a homogeneous, multicomputer, data flow architecture may be defined. This research is concerned with performance modeling and performance enhancement for periodic execution of large-grain, decision-free algorithms in such an ATAMM defined architecture. Performance measures and bounds are established. Algorithm transformation techniques are identified for performance enhancement and reduction of computing element requirements. Operating strategies are developed for optimum time performance and for sub-optimum time performance under limited availability of computing elements. An ATAMM simulator is used to test …

Study Of Direct Semiconductor Materials For An Optically Controlled Switch, Sung Taek Ko

Electrical & Computer Engineering Theses & Dissertations

A model for a bulk GaAs photoconductive switch has been developed and solved to determine the performance of the device in closing and opening switch applications. The GaAs material has been characterized by deep level transient spectroscopy (DLTS). Two electron traps (EL2 and EL5) and one hole trap (Cu_B} have been detected and were included in the model. Simulation studies are performed on several GaAs switch systems composed of different combinations and density of deep levels to investigate the influence of deep traps in a photoconductive switch system. The electron occupancy of each deep trap is traced in …

Anserlin. A Broad-Band, Low-Profile, Circularly Polarized Antenna, James L. Drewniak, P. E. Mayes

Electrical and Computer Engineering Faculty Research & Creative Works

A technique is presented for improving the performance of low-profile, circularly polarized (CP) radiating-line antennas. The essential elements of the technique pertain to establishing a single traveling wave on an annular sector of conducting strip that is positioned parallel and close to a large conducting surface. The antenna is named the annular sector, radiating-line (ANSERLIN) antenna. Using this technique, the impedance bandwidth becomes so large that it no longer has any bearing on the operating bandwidth. Instead, the pattern shape and axial ratio become the factors that limit the bandwidth. Both senses of circular polarization can be transmitted or received …

Pump Pulse Effects In Synchronously Pumped Mode-Locked Dye Lasers, Duncan Leo Macfarlane, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

We consider the role of the pump pulse in the output of a synchronously pumped mode-locked dye laser. Our theoretical formalism is a nonlinear dynamical model that includes semiclassical effects, dipole orientation, and intrband relaxation. In particular, we study the shortenting of the output pulse with decreasing pump pulse length and increasing pump level. Both of these predictions agree with experiments.

Spontaneous Coherent Pulsations In Standing-Wave Laser Oscillators: Frequency Characteristics, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

The output signal from a spontaneously pulsing laser must, by definition, consist of more than one frequency component. The experimental and theoretical study of the frequency components'associated with such a laser can provide valuable insights into the pulsation processes. The results of an investigation into the frequency characteristics of a spontaneously pulsing standing-wave laser are reported.

Application Of Hough Transformation To Detect Ovulatory Patterns In Cervical Mucus Images, Shiliang Wang

Dissertations and Theses

A microcomputer system called ovulocomputer is proposed. The system is used to predict and detect ovulation of women. It will use image processing and analysis, pattern recognition theory, spectrophotometry, ionometry and conductometry to measure various physical and chemical properties of cervical mucus that are related to blood hormone levels.

The functions and characteristics of cervical mucus are introduced in this thesis. Among them, the identification of cervical mucus images, named the ferning test, and related features, are well described.

A new idea, called ferning test automation, which has been neither proposed nor developed before, is presented and explained in detail …

A Microcomputer Based Non-Invasive Cardiopulmonary Monitor Using A Microwave Interferometer, Tanmoy K. Basu

Theses

With a microwave interferometer the vibrational velocity of the anterior (front), as well as posterior (back) chest wall can be monitored and recorded. The recorded signals are a reflection of the mechanical cardiac activity within the chest cavity, as opposed to Electrocardiogram (ECG) which is a reflection of the electrical cardiac activity. The interferometer recordings are obtained with no physical contact between the instrument and the subject. Moreover, the subject can be fully clothed since microwave energy readily passes through normal dry clothing.

A microwave interferometer that is capable of detecting the vibrational velocity of the surfaces of the chest …

Microprocessor-Based Processing Unit Implemented By Xilinx Programmable Logic Array, Lee Chuan Hu

Theses

The 8052 microprocessor-based processing unit is a super single board computer with many unusual features: memory page selecting with page indicators, on-board EPROM/PROM programmer, real time clock, battery back-up RAM, and memory mapped I/O. It is implemented by using Xilinx programmable logic array and can be used for various instruments. Xilinx user-programmable Application-Specific Integrated Circuit (ASIC) is a large logic array with up to 9000 equivalent gates. The advantages of programmable logic devices over standard ICs are more flexibility, design security, lower cost, higher performance, reduced power consumption, smaller size, and increased reliability. The system development time is also greatly …

X.25 Interface Packet Level Simulation, Arvind Tewari

Theses

An X.25 interface was simulated at the packet level and data packets successfully transmitted from the Data Circuit-Terminating Equipment (a process) to the Data Terminal Equipment (another process). This was executed interactively. Two independent processesg were generated on the AT&T 3B15 computer and inter-process communication (IPC) used to transfer the data. The X.25 interface is based on the Open System Interconnection (OSI) model of the International Standards Organization.

A Methodology For Designing Spacecraft Onboard Processing Systems, Mohammad Nadeem Ahmad

Theses

A three layer methodology is presented for designing spacecraft onboard computer systems. The system design is perceived as a sequence of three hierarchical layers: the Dedicated Processing Layer, the Application and Support Processing Layer, and the Communications Processing Layer. Each layer implements a distinct set of functions and offers services at different levels of abstraction. As opposed to the ISO/OSI Reference Model, where the prime objective is to implement peripheral interaction between two systems, the layered approach used here is to address the problems in system design itself. The problem is approached in a bottom-up fashion, starting with the description …