Digital Commons Network^™

Birefringent Light Scattering In Electrooptic Plzt Ceramics, Mark David Ivey

Electrical and Computer Engineering ETDs

A study of visible light scattering in thin plates of ceramic PLZT is presented. A scattering model is developed on the basis of multiple refraction from randomly oriented walls in a birefringent medium. The results of this model are compared to measurements of longitudinal-mode light scattering from thin (250 - 650µm) PLZT plates of three different ceramic compositions. The observed light scattering by these ceramics is attributed to two mechanisms which are linked to field-induced ferroelectric anisotropies. The first, referred to by this study as "uncorrelated birefringence," corresponds to the independently-random changes in the index ellipsoid known to occur at …

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

Electrical and Computer Engineering Faculty Publications and Presentations

Spontaneous pulsation phenomena in xenon lasers are now well known, and related effects have been observed with other laser types. Most theoretical analyses of such pulsations are formulated for unidirectional ring lasers, whereas most experiments involve standing-wave resonator geometries. Described here are rigorous semiclassical models governing the spontaneous pulsation instability in standing-wave laser oscillators. The standing-wave results are more complex and closer to experimental observations than the ring results for operation in the Lambdip region near line center.

Spectral Behavior And Pulse Train Instabilities Of A Synchronously Pumped Mode-Locked Dye Laser, Duncan Leo Macfarlane, Lee W. Casperson, Anthony A. Tovar

Electrical and Computer Engineering Faculty Publications and Presentations

The pulse-train envelope of a synchronously pumped mode-locked dye laser has been experimentally studied as a function of cavity length detuning. When a bandwidth-limiting birefringent tuning filter is included and the cavity is adjusted to the length that yields optimally short (˜2-psec) pulse, there is a slow (≤800 kHz), erratic amplitude modulation that provides a 20% variation in pulse energies. As the cavity length is detuned on the order of one part in 10⁴, the modulation vanishes, but the individual pulse lengths increade dramtically. Further detuning results in a clean periodic envelope with a 20% modulation depth and a˜5-μsec period. …

General Analysis And Optimization Of The Four-Detector Photopolarimeter, R. M.A. Azzam, I. M. Elminyawi, A. M. El-Saba

Electrical Engineering Faculty Publications

The four-detector photopolarimeter (FDP) is analyzed for an arbitrary spatial configuration and any reflection characteristics (r_i, ψ_i, Δ_i) of the first three detectors. The instrument matrix A, which relates the output signal vector I to the input Stokes vector S by I = AS, and its determinant are derived explicitly. The essential condition that A be nonsingular (det A ≠ 0) is satisfied in general with uncoated absorbing detector surfaces, assuming that the plane of incidence (POI) is rotated between successive reflections by other than 90°. Therefore no special coatings on …

Investigation Of Accuracy Limitations Of The Ionospheric Plasma Frequency Probe And Recommendations For A New Instrument, Mark Duane Jensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A unique wide-range voltage-controlled oscillator (VCO) has been part of the plasma frequency probe (PFP) for many years. The uniqueness of this VCO is how it is tuned with an electronic tuneable inductor in conjunction with a varactor diode. Though the PFP has been utilized successfully for rocketborne ionospheric electron density measurements, fine resolution data was limited by strange frequency jumps (approximately 5 percent uncertainty in electron density) which have appeared in flight results. This thesis examines the cause of some of these jumps, and shows they are instrument related and more particularly caused by the ferrite tank inductor core …

Modal Interference Techniques For Strain Detection In Few-Mode Optical Fibers, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

Interference between the modes of an optical fiber results in specific intensity patterns which can be modulated as a function of disturbances in the optical fiber system. These modulation effects are a direct result of the difference in propagation constants of the constituent modes. In this presentation it is shown how the modulated intensity patterns created by the interference of specific mode groups in few-mode optical fibers (V < 5.0) can be used to detect strain. A detailed discussion of the modal phenomena responsible for the observed strain induced pattern modulation is given and it is shown that strain detection sensitivities on the order of 10-9 can be expected. Data taken during the evaluation of an actual experimental strain detection system based on the developed theory is also presented.

Electromagnetic Field Variations In The Activation Of Bone Cell Synthesis, Gary Ketcherside

Loma Linda University Electronic Theses, Dissertations & Projects

[Abstract Not Included]

Self Consistent Model Of The Glow Discharge, Hao Chen

Electrical & Computer Engineering Theses & Dissertations

The strong spatial variation of the electric field intensity in the vicinity of the cathode of a gas discharge requires the use of microscopic methods to describe the nonequilibrium behavior of the electron dynamics in this region. A one-dimensional Monte Carlo code was developed. It allows one to obtain the distribution of the electron drift velocity and rate coefficients for a given electric field intensity in the cathode fall. The results of this calculation are used to find the density distribution of charged particles in this region and consequently, by means of Poisson's equation, a corrected electric field intensity. In …

8085 In-Circuit Emulator For Ibm Personal Computer, Joong Bin Lee

Theses

As microprocessor-based systems become gradually larger, the developers need good tools for debugging the hardware and software. The emulators for the IBM Personal Computer using an RS-232 serial port are available in the market. But it takes quite a long time to download the user file to the memory of the emulator or the target system. This emulator is an add-on card dedicated for IBM Personal Computers. The emulator communicates with the IBM Personal Computer through the I/O channels on the mother board instead of the serial port, so its speed is much faster than that of the serial port. …

The Evaluation Of The Ti-Speech System On Pc Computer, Ying Wu

Theses

A PC-TI-SPEECH system has been set up by the author of this thesis on the IBM PC/AT compatible computer. The basic functions of the system are as follows: data acquisition, internal signal synthesization, signal processing and speech recognition. The system is built up by a PC, TI-Speech Hardware kit, MADCAP software package,TI-Speech Tool kit. This thesis covers the setup, evaluation and operations of the complete PC-TI-SPEECH system, development of the system for further applications, and operations of running some evaluation programs generated by doing this thesis.

Multaid, A Consultant For Multi-Microprocessor Network Selection, Bernabe Javier Arruza

Theses

A knowledge based system has been developed to enable an architectural designer to select an adequate interconnection network to be utilized in a parallel or distributed processing system. It is implemented using the Knowledge Engineering Environment, K.E.E., package from IntelliCorp.

The user will interact with the system through symbolic representation. From the selected symbols, the knowledge base system will identify the most appropiate network for the given application. The system will display the network topology along with all the information and results of all pertinent calculations corresponding to the given network. The program will also display the rule driven search …

Maine Woodburning Guide, Office Of Energy Resources

Maine Collection

Maine Woodburning Guide

State of Maine, Office of Energy Resources,

Augusta, Maine, 1988.

Contents: 1 Safe Installation / 2 Buying Firewood / 3 Efficient Woodburning / 4 New Equipment Developments / 5 Chimney and Stovepipe Cleaning

Architectural Considerations For Photonic Switching Networks, Harvard S. Hinton

Electrical and Computer Engineering Faculty Publications

Photonic technologies are reviewed that could become important components of future telecommunication systems. Photonic devices and systems are divided into two classes according to the function they perform. The first class, relational, refers to devices, that map the input channels to the output channels under external control. The second class, logic, perform some type or combination of Boolean logic functions. Some of the strengths and weaknesses of operating in the photonic domain are presented. Relational devices and their applications are discussed. Optical logic devices and their potential applications are reviewed.

A Piezoelectric Actuated Scanning Mirror System Utilizing A Type One Control Loop, David Gibbs

Retrospective Theses and Dissertations

The purpose of this thesis is to design and build an improved control loop for a piezoelectric actuated scanning mirror system. A control system has been built having zero steady state position error and an 80 Hertz bandwidth. This was achieved by placing the piezoelectric actuator in the feedback path of an operational amplifier and placing series cascaded notch filters and lead compensators in the forward path of the control loop. A prototype system, including compensation and feedback, is developed. Its performance compares favorably with that of the system model. It is capable of plus and minus 1.7 degrees of …

Barium Borate In Parametric Oscillation And 1.54 Micron Generation, Mark Kerrigan

Retrospective Theses and Dissertations

As to date, there are several relatively new crystals that have been developed for nonlinear or "parametric" optical applications, including KTP, LAP, KNbO3, m=NA, and BaB204 (barium borate, or simply BBO). The latter crystal, BBO, and the use of BBo to achieve parametric oscillation around an eyesafe wavelength of 1.54 microns is the emphasis of this paper.

Unpublished material includes determining the optimum type of coupling and pump wavelength used when generating 1.54 μm eyesafe radiation based upon Poynting vector walk off, suscpetibilityies, and both signal angular and spectral acceptance widths. Poynting vector walk off curves for linearly polarized extraordinary …

Uniform Energy Discharge For Pulsed Lasers, Eric Calvin Koschmann

Retrospective Theses and Dissertations

The art of achieving a large energy discharge in a controlled manner with relative ease is to use a pulse forming network. Historically the design of such networks generally used a single inductor and capacitor. Although easy to design and implement, this practice does not provide optimum performance in all cases. In particular, most laser welding requires a uniform energy discharge in a pulse to produce a high quality weld. Analysis has shown that when the pulse forming network approximates a lumped constant transmission line a maximum flat pulse is produced with minimal degradation of the pulse rise time. This …

Design Of A Bandpass Oculometer, Karin Brandauer

Retrospective Theses and Dissertations

A passive oculometer is a device that measures the position of the eye by utilizing the corneo-retinal potential (CRP) generated by the eye. In this thesis, the Bandpass Oculometer replaces the joystick of a personal computer, allowing the viewer to use a computer simply by moving his eyes. Low frequency noise, present in all electronic circuits, produces an offset from the reference point, the center of the screen. In previous lowpass oculometry studies at University of Central Florida, this offset caused the cursor to drift toward the edge of the field of view within a period of 30 seconds, decreasing …

Computer Aided Design Of Linear Phase Finite Impulse Response Digital Filters, Wentao Lyou

Retrospective Theses and Dissertations

This research report is an investigation of techniques for designing linear phase finite-duration impulse response (FIR) filters. The software package, CADFIR, developed for this project can be used to design linear phase FIR digital filters via three well-known design techniques: the window method, the frequency sampling method, and the optimal filter design method. CADFIR has options for designing such standard filters as lowpass, highpass, bandpass, and bandstop filters as well as multipassband-stopband filters. The fundamental properties of FIR filters are discussed and design algorithms associated with the three FIR filter design techniques are developed. Design examples are included and the …

An Ada Simulator For The Structured Functional Simulation Of A Digital Signal Processing System, Christopher Paul Roney

Retrospective Theses and Dissertations

A behavioral-level simulator designed for FIRST, a silicon compilation system for digital signal processing, is implemented in the Ada* programming language. The simulator accepts as input a digital signal processing system description written for the FIRST ([ast Implementation of aealtime ~ignal transforms) silicon compiler, and provides an interactive post-processing signal trace facility. The simulator is a time-driven simulator which contains a FIRST description language parser, a subset of the FIRST primitives, and the capacity for maintaining a full history of all signals in the system. The primitives in the FIRST description language are common to digital signal processing systems (e.g., …

A Bulk Optically Controlled Semiconductor Switch, Rudolf K.F. Germer, Karl H. Schoenbach, Stephen G.E. Pronko

Bioelectrics Publications

Turn‐on and turn‐off of bulk semiconductor switches, based on excitation and quenching of photoconductivity, respectively, have been demonstrated with copper‐doped II‐VI semiconductor crystals. The increase of the conductivity (turn‐on) was realized with a xenon flash‐lamp pulse of 15‐μs duration. A reduction of the conductivity (turn‐off) was obtained by irradiating the samples with IR light using an 8‐ns Nd:YAG laser pulse (YAG denotes yttrium aluminum garnet). For turn‐on in CdS:Cu the conductivity follows the xenon flash excitation. The turn‐off time constant was 250 ns. ZnS and ZnSe crystals showed a slower response. A memory effect for the IR light was observed.

A Three-Dimensional Bistatic Radar Target Position Measurement Error Model, Robert Kenneth Lynn

Masters Theses

"The accuracy of target position measurements for an airborne bistatic radar receiver are calculated. Two methods of information measurement are utilized, both of which assume cooperative synchronization between the transmitter and receiver. Gimbal angle errors are incorporated into both methods. The size and orientation of the error ellipsoid about the true target position is found. Loci of constant circular error probable are plotted in a horizontal plane of interest"--Abstract, page ii.

Laser Induced Darkening Semiconductor Dope Glasses, Jayant Malhotra

Retrospective Theses and Dissertations

No abstract provided.

Optical Interferometric Formation Of Phased Array Antenna Footprint/, John E. Sherwood

Retrospective Theses and Dissertations

A 40 dB gain RF Low Noise Amplifier (LNA) matched to a photodiode input is designed using TOUCHSTONE (S-parameter based CAD software), built, and tested. The RF LNA formed the detector of a Mach-Zehnder interferometer constructed with single mode fiber, coupler, Gradient Index Rod Acousto-optic modulator (ADM) . (GRINROD) lenses, and an The ADM is used to frequency shift the optical frequency by 125 MHz, and the motion of a GRINROD lens is used to produce an optical phase shift that is recovered at the detector as an electrical phase shift by using heterodyne detection . Finite Hankel transforms are …

Rise Time To Frequency Correlation Of Crosstalk In Coupled Microstrip Lines, Charles Michael Fletcher Jr.

Retrospective Theses and Dissertations

An examination of forward crosstalk in microstrip transmission lines is presented through a computer simulation using SPICE. A non-resistive lumped L-C transmission line model is modified to include capacitive and inductive coupling from adjacent lines. Two adjacent microstrip transmission lines are modeled, and simulation results in both the time and frequency domains are shown. The time domain or transient analysis looks at the effect of rise times on crosstalk. Rise times in the range of 100 to 1000 nanoseconds (ns) are considered. The frequency analysis shows the crosstalk frequency response over the range of 100 to 1600 kilohertz (kHz). The …

Aircraft Vertical Profile Implementation Using Directed-Graph Methods, L. T. Brewster, Paul D. Stigall

Electrical and Computer Engineering Faculty Research & Creative Works

Aircraft Vertical Profile Simulation is Realized using a Demand-Driven Minimal-Calculation Directed Graph Structure to Reduce Calculation Time and to Force Synchronization of the Performance Measurement Functions with the System State Variables. Performance-Directed Model Adaptation Makes Dynamic Vertical Profile Path Corrections, in the Presence of Fixed Drag Variations, Possible. Drag Variations Ranging from + 10 Percent to - 10 Percent Yielded Fuel Consumption Improvements of Less Than 1 Percent in the Majority of the Cases. Calculation Time Improvement for Path Simulation Ranges from a Factor of 1.19 in the Worst Case to 1.5 in the Best Case. © 1988 IEEE

A System For Measuring The Phase Difference Between Two Points Of A Propagating Laser Beam, Jefferson E. Odhner

Retrospective Theses and Dissertations

An optical system has been designed, analyzed, implemented, and calibrated which measures the phase difference between two points of a propagating laser beam. The system is a quadrature interferometer whose detector outputs are processed by a computer. This quadrature interferometer measures both the phase and amplitude variations between two points of a laser beam after the beam passes through turbulence . These measurements are in turn processed by a computer to isolate the phase variations from the amplitude variations. Further statistical analysis which can be performed on these phase variations should provide an understanding of the phase fluctuations of propagating …

Method For Sizing Mos Transistors For Vlsi, Matthew J. Amatangelo

Retrospective Theses and Dissertations

Determining the device width to length ratios has typically been an iterative process for the custom IC digital design engineer. After the logic design phase is complete for a particular circuit, the designer would make an educated guess at the device sizes. Then by trial and error, using SPICE or another circuit simulator, suitable sizes would be determined. Unfortunately, this approach is time consuming and the resulting sizes are often a good bit larger than they need to be to maintain a certain speed because of the lack of a rigorous sizing methodology. This paper describes a method for reducing …

A Stochastic Model For Dielectric Breakdown In Thin Capacitors, D. A. Willming, Cheng-Hsiao Wu

Electrical and Computer Engineering Faculty Research & Creative Works

A nontrivial two-dimensional stochastic model for dielectric breakdown within a parallel plate capacitor is presented for the first time. The model has been used to determine geometric properties of parallel plate discharges. Comparisons are made between these properties and known fractal properties of electrostatic discharges within cylindrical geometries. As the spacing between the plates of a capacitor increases, the value of the fractal dimension of the associated discharge structure increases from the minimum value of unity and approaches the limiting value corresponding to the case of infinite spacing. For any given spacing, this fractal exponent is equal to the exponent …

Evidence For Band-Gap Narrowing Effects In Be-Doped, P-P+ Gaas Homojunction Barriers, H. L. Chuang, Paul David Demoulin, M. E. Klausmeier-Brown, Michael R. Melloch, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

The electrical performance of Be‐doped, p‐p+ GaAs homojunction barriers is characterized and analyzed. The results of the analysis show that minority‐carrier electrons, at 300 K, have a mobility of 4760 cm2/V s at a hole concentration of 2.3×1016 cm−3, and that the effective recombination velocity for these homojunction barriers is about 6×104 cm/s. We present evidence that this unexpectedly high recombination velocity is a consequence of an effective reduction in band gap due to the heavy impurity doping. The effective band‐gap shrinkage in this Be‐doped material grown by molecular‐beam epitaxy appears to be comparable to that already …

Effects Of Heavy Impurity Doping On Electron Injection In P+-N Gaas Diodes, M. E. Klausmeier-Brown, Mark S. Lundstrom, Michael R. Melloch, S. P. Tobin

Department of Electrical and Computer Engineering Faculty Publications

Measurements of electron injection currents in p+‐n diodes are presented for a range of p‐type dopant concentrations. A successive etch technique was used to characterize the electron injection current in terms of the product (noDn). Measurements are presented for Zn‐doped GaAs solar cells with p‐layer hole concentrations in the range 6.3×1017−1.3×1019 cm−3. The results demonstrate that so‐called band‐gap narrowing effects substantially increase the injected electron current in heavily doped p‐type GaAs. These heavy doping effects must be accounted for in the modeling and design of GaAs solar cells and heterostructure …