Digital Commons Network^™

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 …

Efficient Multi-Layer Channel Routing, Ronald I. Greenberg

Computer Science: Faculty Publications and Other Works

No abstract provided.

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.

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.

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 …

Generation Of Atomic Nitrogen By Gas Discharge In Microwave Cavity, Jong-Shun Shieh

Theses

A microwave discharge system for producing atomic nitrogen at low flow rate and low pressure has been investigated. The molecular nitrogen passes through a microwave cavity in a quartz tube and is dissociated by the microwave energy. Subsequent recombination of nitrogen atoms produces a characteristic yellow glow due to the relaxation of excited molecular nitrogen to its ground state. The titration of nitric oxide with atomic nitrogen was used to measure the atomic nitrogen yield. At a 2 sccm nitrogen flow rate the atomic nitrogen yield was 8.75*10¹⁵ atom/sec, which corresponds to a nitrogen generation efficiency of about 1%. …

A Wideband Continuous Phase Shifter For Ka-Band, William J. Tanis

Theses

The design, fabrication and test of a 45 degree microstrip phase shifter capable of full Ka-band performance is presented. The design uses a Lange coupler with two ports terminated with beam-lead varactor diodes to provide continuous phase shift. Although this concept has been employed at X-band and below, this thesis demonstrates its feasibility for wideband use at frequencies as high as 40 GHz. The design uses thin-film capacitors, beam-lead diodes, simulated grounds, and air bridges to achieve a planar geometry and to simplify the production process. Detailed test results using various test circuits are shown for comparison to actual phase …

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.

Design Of A Lan Based Data Acquisition System For Sensor Applications, Krishna Murthy Uppunda

Theses

This thesis presents the design of a local area network (LAN) based data acquisition system for sensor applications. The circuit designed forms the robotic LAN (RLAN) interface between the sensor IC nodes and the ARCNET network. The RLAN network uses two packet protocols. The sensor data request (SDR) packet is received by the sensor IC nodes and the sensor transmits the sensor data (SD) packet. The RLAN interface provides a two way communication between the sensors and the ARCNET network. Whenever an ARCNET node receives the SDR packet, it stores the packet temporarily in a 1k RAM buffer. The RLAN …

Use Of The Lms Algorithm In Ecg Analysis, Xiaohua Yang

Theses

The purpose of this thesis is to develop an IBM PC-AT based system to effectively process electrocardiogram (ECG) signals. Adaptive filter theory is used to implement a noise cancellation system (adaptive noise canceller), which adaptively cancels the ECG signals resulting in real ECG noise. The adaptive process is based on the well known least-mean square (LMS) algorithm.

The noise canceling system is software based. Several programs have been written, which include analog to digital converter control, data acquisition and storage, data retrieval, adaptive filtering and digitized data graphics.

The thesis presents numerous computer experiments. The performance of the adaptive noise …

Design Of A Temperature Sensor For Gallium Arsenide Ic Applications, Raviprakash Raviprakash Gutala

Theses

This thesis presents the design of a temperature sensor circuit including sensor, differential amplifier, and a memory element for gallium arsenide IC standard cell applications. A standard 1-um depletion-mode GaAs MESFET technology has been used for the design of the circuit. The circuit is intended to be used as a standard cell in GaAs les providing an alarm when the sensor temperature reaches 125 °C. The circuit includes a NAND latch which is set when the chip cell temperature reaches 125 °C. The output of the latch can be sensed by additional circuits (on or off the GaAs chip) which …

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 …

Reliability Problems And Failure Mechanisms In Ic Packaging, Dilip J. Patel

Theses

Today, reliability is acknowledged as an important item in design and operation of electronics circuits and system.

This thesis provides information on evaluation of the reliability for hermetic and non hermetic IC packages made by different manufacturers.

Literature study concentrates on the reliability and related problems in IC packages developed between 1970 and 1988.

Several failure mechanisms and failure modes are discussed to point out how higher reliability in IC packages may be achieved.

The bibliography is given in a chronological order to help further research in this area.

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 …

A Cmos Digital Temperature Sensor For Asic Vlsi Standard Cell Design, Chih-Ta Sung

Theses

This thesis describes the design of a CMOS digital temperature sensor cell including the physical layout database.This cell is designed for implementation within an ASIC VLSI chip as a standard cell . The digital temperature sensor can trigger an alarm signal and turn off power for preventing fatal damage in the VLSI chip if overheating occurs.A digital output also permits measurement of temperature over the 0 - 120°C range with ±3.4°C accuracy using standard VLSI foundry processing. Two sensing elements are implemented in a differential mode within the temperature sensor cell. An operational amplifier is used in the successive approximation …

Theoretical Model For The Images Formed By A Spherical Particle In A Coherent Imaging System: Comparison, Scott Alan Schaub, D. R. Alexander, J. P. Barton

Department of Electrical and Computer Engineering: Faculty Publications

A simple theoretical model is presented that allows calculation of the image produced by a spherical absorbing particle illuminated by monochromatic, coherent laser light. Results presented in this paper are restricted to a singe-lens imaging system, although generalization to more complex imaging system configurations would be straightfoward. The method uses classic Lorenz-Mie scattering theory to obtain the electromagnetic field external to an absorbing spherical particle and a Fourier optics approach to calculate the intensities in the image plane. Experimental results evaluating focus characteristics are examined for 50 um diameter water droplets using an N2 laser imaging system in conjunction with …

Assessment Of Squirrel-Caused Power Outages, J. Chris Hamilton, Ron J. Johnson, Ronald M. Case, Michael W. Riley

School of Natural Resources: Faculty Publications

Squirrel-caused power outages in Lincoln and Omaha, Nebraska, were evaluated by examining company power outage reports and by consulting with power company representatives. Reports showed that squirrel-caused outages at pole-mounted transformers were most prevalent during May, June, and October (48% of total) and between 1 and 4 h after sunrise (38%), patterns that coincide with squirrel dispersal or morning activity periods. In Lincoln, 1980 and 1981, squirrels caused 177 outages per year, which was 24% of all outages and 90% of animal-caused outages. Estimated minimum annual costs were $23 364 for repairs, public relations, and lost revenue while meters were …

Feasibility Study Of Maine's Small Hydropower Potential, James D. Sysko

Maine Collection

Feasibility Study of Maine's Small Hydropower Potential

Prepared by James D. Sysko, Small Hydro East, for the Maine State Planning Office, Maine Office of Energy Resources, January 1989.

"This study focuses on finding potential hydropower sites of approximately 50 kw to 1000 kw in capacity."

Symmetric Self-Electro-Optic Effect Device: Optical Set-Reset Latch, Differential Logic Gate, And Differential Modulator/Detector, Anthony L. Lentine, Harvard S. Hinton, David A. B. Miller, Jill E. Henry, J. E. Cunningham, Leo M. F. Chirovsky

Electrical and Computer Engineering Faculty Publications

The symmetric self-electrooptic-effect device (S-SEED), a structure consisting of two p-i-n diodes electrically connected in series and acting as an optically bistable set-reset latch, is discussed. Applications and extensions of this device are also discussed. The devices do not require the critical biasing that is common to most optically bistable devices and thus is more useful for system applications. They have been optically cascaded in a photonic ring counter and have been used to perform different NOR, OR, NAND, and AND logic functions. Using the same device, a differential modulator that generates a set of complementary output beams with a …

Generalized Model For The Optical Absorption Edge In A-Si:H, T. Datta, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

We have reanalyzed the published optical absorption coefficient data for a-Si:H and introduced a divergence temperature, a new concept in the physics of these materials.

A Pulsed Field-Gradient System For Nuclear Magnetic Resonance Diffusion Experiments, Saumil Shirish Mehta

Masters Theses

"The construction and performance of a system to generate pulsed magnetic field gradients for use with a commercial superconducting NMR spectrometer for the purpose of molecular self-diffusion measurements is described. Types of coils that provide linear field gradients are discussed. The design and construction of a conventional Helmholtz pair is outlined. A procedure to estimate the magnitude of the field gradients generated by the Helmholtz coils is explained. The design of a circuit to generate fast current pulses using a power MOSFET has been detailed and compared with a functionally similar circuit using bipolar power transistors. The performance of the …

Consequences Of Valley Filtering On Abrupt Junction Algaas/Gaas Heterojunction Bipolar Transistors, Amitava Das, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

Electron transport in AlGaAs/GaAs heterojunction bipolar transistors with compositionally abrupt emitter‐base junctions is examined. Transport across the abrupt emitter‐base heterojunction is treated quantum mechanically, and the Monte Carlo technique is used to study transport through the base. Although there is a sizeable population of upper‐valley electrons in the bulk emitter, the AlGaAs/GaAs heterojunction is found to favor the injection of Γ‐valley electrons into the base. This valley filtering effect enhances device performance by reducing base transit time, but quantum mechanical tunneling lowers the average energy of the injected flux which increases base transit time. The design of a heterojunction bipolar …

Effective Minority‐Carrier Hole Confinement Of Si‐Doped, N+‐N Gaas Homojunction Barriers, H. L. Chuang, M. E. Klausmeier-Brown, Michael R. Melloch, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

he electrical performance of Si‐doped n+‐n GaAs homojunction barriers grown by molecular‐beam epitaxy (MBE) is characterized and analyzed. We employed a successive etch technique to study hole injection currents in GaAs n+‐n‐p+ solar cells. The results of the analysis show that minority‐carrier holes in our MBE‐grown material have a mobility of 293 cm2/V s for an n‐type Si‐doping level of 1.5×1016 cm−3 at 300 K. The interface recombination velocity for these homojunction barriers is estimated to be less than 1×103 cm/s, and it appears to be comparable to that recently observed for …

The Multiprocessor System With A Fairly Weighted Global Bus Arbitration Circuit, Shinobu Doi

Theses and Dissertations

The objective of this thesis is to investigate various multiprocessor system structures and to implement and test the resultant system configuration that offers high reliability and availability, ease of expansion, ease of programming, and increased computing performances. The resultant system is a MC68000 based tightly coupled multiprocessor system with large local memories and local I/Os, arbitrated by a specially designed arbitration circuit to implement pseudo random global bus granting. Each of the computer modules is an enhanced independent uniprocessor system with channel access switches to access the global memory. In its multiprocessor mode one computer module cooperates with the other …

Design Of The Electronics And Optics Needed To Support Charge-Coupled Devices : A Project Report ..., Kah Yep Zee

University of the Pacific Theses and Dissertations

Over the last five years, charge-coupled devices (CCD) have been improved dramatically in terms of sensitivity, manufacturability and particularly, cost. This has enabled them to be used economically in many more industrial and commercial electronic imaging processes. They are found in products ranging from video cameras to satellite-based camera systems. This has sparked my interests in these devices, and with a great deal of encouragement from Dr. Turpin, I decided to base my Master's thesis/project on a CCD. The project was mainly based on the design of the electronics and optics needed to support a CCD. The particular circuit design …

Optical Recording Aspects Of Rf Magnetron Sputtered Iron-Garnet Films, J.P. Krumme, V. Doormann, P. Hansen, H. Baumgart, J. Petruzzello, M.P.A. Viegers

Electrical & Computer Engineering Faculty Publications

The intrinsic magneto-optical readout performance in reflection is calculated for bismuth and cobalt-substituted iron-garnet films on a multilayer interference mirror at 800-, 633-, 488-, and 420-nm wavelengths and is compared with that of a trilayer medium composed of an antireflection layer, a rare-earth transition-metal film, and a metallic mirror. It is found, when disregarding inhomogeneities, like irregular domain shape, ripple of the magnetic anisotropy, and surface roughness, that iron garnets are superior to rare-earth transition-metal films at blue to near-ultraviolet wavelengths if operated at thicknesses where optical interference occurs in the magnetic layer. Optical transmittance at these thicknesses is sufficiently …

Nanosecond Optical Quenching Of Photoconductivity In A Bulk Gaas Switch, M. S. Mazzola, K. H. Schoenbach, V. K. Lakdawala, S. T. Ko

Electrical & Computer Engineering Faculty Publications

Persistent photoconductivity in copper-compensated, silicon-doped semi-insulating gallium arsenide with a time constant as large as 30 µs has been excited by sub-band-gap laser radiation of photon energy greater than 1 eV. This photoconductivity has been quenched on a nanosecond time scale by laser radiation of photon energy less than 1 eV. The proven ability to turn the switch conductance on and off on command, and to scale the switch to high power could make this semiconductor material the basis of an optically controlled pulsed-power closing and opening switch.

Randomized Routing On Fat-Trees, Ronald I. Greenberg, Charles E. Leiserson

Computer Science: Faculty Publications and Other Works

Fat-trees are a class of routing networks for hardware-efficient parallel computation. This paper presents a randomized algorithm for routing messages on a fat-tree. The quality of the algorithm is measured in terms of the load factor of a set of messages to be routed, which is a lower bound on the time required to deliver the messages. We show that if a set of messages has load factor lambda on a fat-tree with n processors, the number of delivery cycles (routing attempts) that the algorithm requires is O(lambda + lg n lg lg n) with probability 1-O(1/n). The best previous …

Lower Bounds On The Area Of Finite-State Machines, M. J. Foster, Ronald I. Greenberg

Computer Science: Faculty Publications and Other Works

There are certain straightforward algorithms for laying out finite-state machines. This paper shows that these algorithm are optimal in the worst case for machines with fixed alphabets. That is, for any s and k, there is a deterministic finite-state machine with s states and k symbols such that any layout algorithm requires Ω(ks log s) area to lay out its realization. Similarly, any layout algorithm requires Ω(ks^2) area in the worst case for nondeterministic finite-state machines with s states and k symbols.