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Coherence Effects In Synchronously Pumped Mode‐Locked Dye Lasers, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

A formalism is developed for describing the evolution of picosecond mode‐locked pulses in synchronously pumped dye lasers. The finite phase memory of the molecular wave functions is included, and it is found that the resultant coherence effects can be dominant for operation close to exact synchrony. Considerations of the isotropic molecular orientational distribution and the finite vibrational relaxation times are also essential in obtaining quantitative agreement with experimental results.

Adaptive Delta Modulation, Aliuddin Ahmad

Theses

The objective of this thesis is the study of the performance of instantaneously companded adaptive delta modulation (ADM) systems in comparison with linear delta modulation (LDM) in terms of signal to quantization noise ratio (SNR). Various schemes for ADM are discussed and their advantages and disadvantages are indicated. SNRs are calculated by simulation, with IBM's continuous system modeling programming (CSMP) language being used as a tool for simulation. LDM, first and second order constant factor delta modulation (CFDM), has been simulated and responses for different types of input signals are presented.

Polarization-Preserving Single-Layer-Coated Beam Displacers And Axicons, R. M.A. Azzam, M. Emdadur Rahman Khan

Electrical Engineering Faculty Publications

A design procedure is described to determine the thicknesses of single-layer coatings of a given dielectric on a given metallic substrate so that any input polarization of light is preserved after two reflections at the same angle of incidence from a parallel-mirror beam displacer or an axicon. This is achieved by equalizing the net complex p and s reflection coefficients (also called the radial and azimuthal eigenvalues of an axicon) after two reflections. The net polarization-independent reflectance (insertion loss) of the device is computed and found to exceed the net minimum parallel reflectance of the uncoated device for incidence above …

Scheme To Polarization-Correct A Waxicon, R. M.A. Azzam

Electrical Engineering Faculty Publications

No abstract provided.

Stationary Property Of Normal-Incidence Reflection From Isotropic Surfaces, R. M.A. Azzam

Electrical Engineering Faculty Publications

The complex reflection coefficients for the parallel (p) and perpendicular (s) polarizations of light that are normally incident upon an isotropic surface are proved to be stationary with respect to small changes of the angle of incidence in the neighborhood of zero. This is true not only for a single interface between isotropic media but also for any one-dimensionally inhomogeneous or multilayer reflecting structure that is stratified in the direction of the surface normal. For incident light of certain intensity, phase, and polarization, the intensity, phase, and polarization of the reflected light all remain stationary with …

An Investigation To Model Radar Backscatter From Ridged First Year Sea Ice, Betty Lou W. Jackson

Electrical & Computer Engineering Theses & Dissertations

This thesis investigates the response of a radar type sensor, the microwave scatterometer, to meter scale roughness of first-year sea ice. The scatterometer measures the absolute backscattered power from a target, and use of the radar equation permits calculation of the surface reflectivity expressed as the radar scattering coefficient, σ⁰ also called the normalized radar cross section. This thesis develops an empirical, one dimensional model to predict the backscattered power from ridged first-year sea ice of known surface topography, by interpreting the surface as a series of angular facets and summing the proportional power from each facet. The model …

Thermal Hysteresis In Acoustic Resonators, Lee W. Casperson, Lloyd M. Davis, John D. Harvey

Electrical and Computer Engineering Faculty Publications and Presentations

In some applications of piezoelectrically driven acoustic resonators, the power dissipated in the resonating material may be sufficient to significantly change the temperature and hence the resonance frequency. A straightforward analysis shows that this effect can lead to severe hysteresis and thermal bistability. This model is in agreement with experiments that have been performed using a fused silica acousto‐optic modulator.

Remote Attitude Measurement Techniques, Frank John Elmer

Dissertations

A method has been developed for solving practical problems which can be expressed in terms of physical geometry. These problems often involve combining directional information observed by remotely located sensors reported in their own respective local coordinate systems. To transform this information into a common coordinate system, the attitude of the sensors must be measured with respect to this common coordinate system.

Physical geometry is a generalization of mathematical -geometry where objects define the endpoints of figures composed of ensembles of lines. A probabilistic approach has been taken which is based on the fundamental assumption that the objects can be …

Pattern Generation And Fault Detection In Digital Circuits Using A Microprocessor, Syed Riffat Ali

Theses

The main object of this Professional Project was to establish a microcomputer based system which could detect faults in digital circuits. Hardware and software for the Motorola 6800 microcomputer system was fully developed. Node level diagnostic programs were then used to pump known "Bit Patterns" into digital circuits and responses recorded via Pseudorandom binary sequence generator using CRC code. This method also known as "Signature Analysis" was then applied to detect faults successfully in Universal Asynchronous Receiver Transmitter or UART Circuits.

Study Of Compositional Changes (Altered Layer) In (Hg,Cd)Te Targets Sputtered With Hg Vapor, Robert Granville Bourne

Theses

Six mercury cadmium telluride targets (5.74 cm diameter) with six polycrystalline (Hg_0.8 Cd_0.2 )Te ingots (1 x 3 x 0.7 cm ± 20%) epoxied on them, were r.f. sputtered in an MRC-8800 triode system for 1, 2, 3, and 5 minutes. The six sputtering runs were made with 3 different Hg pressures of 1.0, 1.25, and 1.6μm while the uniform target power density was kept constant at 7.7W/cm². After sputtering a target, Br₂ +CH₃OH was used to chemically etch the sputtered ingots to different depths. The surface composition of the etched ingots was …

Final Project Report: Development Of A Hydrogen Fueled Transit Vehicle, C. A. Maccarley

Electrical Engineering

No abstract provided.

Brewster And Pseudo-Brewster Angles Of Uniaxial Crystal Surfaces And Their Use For Determination Of Optical Properties, M. Elshazly-Zaghloul, R. M.A. Azzam

Electrical Engineering Faculty Publications

Brewster and pseudo-Brewster angles are defined for surfaces of transparent and absorbing uniaxial crystals parallel and perpendicular to the optic axis. Two Brewster angles of a transparent uniaxial crystal surface parallel to the optic axis, measured when the optic axis is oriented perpendicular and parallel to the plane of incidence, readily determine the ordinary and extraordinary indices N_o and N_e. N_o and N_e can also be obtained from two Brewster angles measured on a surface perpendicular to the optic axis in contact with two media of different refractive indices. Conditions for the existence of two …

A Unique Microprocessor Instruction Set, D. A. Fairclough

Faculty Publications

New instruction sets have been based on traditather than on the application of scientific method. Here, the latter has yielded a simple, optimal, en-member instruction set.

Modes Of A Laser Resonator With A Retroreflecting Corner Cube Mirror, Guosheng Zhou, Anthony J. Alfrey, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

The self-consistent integral equation for the field distribution of the resonant modes in a resonator with a tilted retroreflecting corner cube mirror is solved. The corner cube acts like a convex lens with radius of curvature -L cot²Ө in the rotation direction (L is the cavity length and Ө the rotation angle) and like a flat plane in the direction of the rotation axis. The field distribution can be described in terms of Hermite-Gaussian functions, and these results have been confirmed experimentally using an Ar-ion laser. The equivalent beam matrix for a reflecting corner cube is also found.

A Pattern Analysis Algorithm For Wind Ambiguity Removal, Jaime R. Tormos

Electrical & Computer Engineering Theses & Dissertations

Some remote sensing devices, such as satellite microwave scatterometers, produce sampled wind vectors that are accurate in speed and streamline direction, but have a directional ambiguity of 180°. The extraction of information from the two dimensional wind vectors is readily handled using pattern analysis techniques. It is shown that there is sufficient information in the spatial relationships of the generated windstream vectors to recognize the driving meteorological wind patterns. This then leads to the resolution of the wind ambiguity problem. This thesis presents the development of a pattern analysis algorithm that generates a measure of the raw data set that …

Efficient Infrared Upconversion In Gap, M. A. Gundersen, T. A. Yocom, P. G. Snyder, P. F. Williams

P. F. (Paul Frazer) Williams Publications

Mechanisms for linear conversion of infrared to visible were investigated in extrinsic Gap. Efficient (1 %) conversion of 10 micron to visible was observed in GaP:Zn,O. Several device applications are discussed and a quantum counter scheme involving 111-V photocathodes is presented.

Constant-Psi Constant-Delta Contour Maps: Applications To Ellipsometry And To Reflection-Type Optical Devices, A.-R. M. Zaghloul, R. M.A. Azzam

Electrical Engineering Faculty Publications

Constant-psi constant-delta contour maps in the reduced angle-of-incidence-film-thickness plane that are useful in ellipsometry and in design of reflection-type optical devices are discussed. As a specific example, a contour map is given for the SiO₂-Si film-substrate system at the 6328-Å He-Ne laser wavelength.

Simple Powerful Tunable Single-Mode And Mode-Locked Tea Co2 Laser, R. A. Dougal, M. A. Gunderson, P. F. Williams

P. F. (Paul Frazer) Williams Publications

A simple method for constructing a single longitudinal-mode CO₂ laser that is tunable within individual rotational transitions is presented. Useful power levels, typically 0.3 J per pulse in a single-mode beam, are obtained from a single-stage device. Mode-locked output can also be obtained from the laser. In addition, design and construction of a local oscillator for making absolute in situ frequency measurements is described.

A Control Program And Operating System For A Three Joint Robot Arm On An Apple Microcomputer, Eric Henry Stelzer

Masters Theses

"A Robotics Operating and Control System for a three-joint robot arm model is presented. The general operation of the system in interfacing the robot to the operator is discussed. Kinematic equations for the robot are derived and commands available to the operator are covered in some detail. The operation of the Control System in moving the robot is explained. Finally, suggestions are made for further development of the system"--Abstract, page ii.

An Optimal Control Law By Eigenvalue Assignment For Improved Dynamic Stability In Power Systems, A. B.R. Kumar, Earl F. Richards

Electrical and Computer Engineering Faculty Research & Creative Works

Whenever control laws are computed on the basis of linear optimal control theory and implemented on non-linear systems, such as power systems, the performance is not as good as expected because of saturation type non-linearities in the system components. The only way to ensure that a control law is adequate, short of actually testing the real system, is to observe the simulated behavior of the system. Departure between a calculated linear control law and the actual response can be minimized by (a) computing a feedback control law with gains of small magnitudes to achieve a pre-assigned set of eigenvalues for …

An Analytical Method For Quantifying The Electrical Space Heating Component Of A Cold Load Pick Up, Walter W. Lang, Max Darwin Anderson, David R. Fannin

Electrical and Computer Engineering Faculty Research & Creative Works

After an extended cold weather outage on a distribution circuit supplying a high saturation of electrical space heating, large transient overcurrent's persist for several hours because of the undiversified heating load. In this paper, the electrical space heating component of enduring demand is characterized by a smooth curve. Expressions are derived for the parameters of the curve in terms of the outage conditions and a statistical description of the residences. A method is suggested for using this characterization to determine the effects of a cold load pick up on the distribution circuit components. Copyright © 1982 by The Institute of …

Generalized Running Discrete Transforms, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

This Paper Introduces a Generalized Running Discrete Transform with Respect to Arbitrary Transform Basea, and Relates the Generalized Transform to the Running Discrete Fourier Z and Short-Time Discrete Fourier Transforms. Concepts Associated with the Running and Short-Time Discrete Fourier Transforms Such as 1) Filter Bank Implementation, 2) Synthesis of the Original Sequence by Summation of the Filter Bank Outputs, 3) Frequency Sampling, and 4) Recursive Implementations Are All Extended to the Generalized Transform Case. a Formula is Obtained for Computing the Transform Coefficients of a Segment of Data at Time N Recursively from the Transform Coefficients of the Segment of …

A Performance Study Of 16-Bit Microcomputer-Implemented Eft Algorithms, Paul D. Stigall, Rodger E. Ziemer, L. Hudec

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Deposition Of Cdte By Spray Pyrolysis, Jack L. Boone, Thomas P. Van Doren, Alok K. Berry

Electrical and Computer Engineering Faculty Research & Creative Works

We report the spray pyrolysis of thin films of CdTe which show promise as a base material for solar cell applications. The films predominately show a zinc blende structure and appear to be intrinsic. Microprobe analysis indicates an excess of cadmium but this is not detectable by X-ray diffraction or from electrical conduction measurements. Measurements indicate a nominal direct bandgap of 1.47 eV and an absorption coefficient of the order of 104 cm−1. The room temperature electrical resistivity is of the order of 107 Ω cm.

Applying Software Complexity Metrics To Program Maintenance, Kenneth Magel, Raymond Michael Kluczny, Warren A. Harrison, Arlan R. Dekock

Business and Information Technology Faculty Research & Creative Works

No abstract provided.

Seeded Oscillatory Growth Of Si Over Sio² By Cw Laser Irradiation, G.K. Celler, L. E. Trimble, K.K. Ng, H.J. Leamy, H. Baumgart

Electrical & Computer Engineering Faculty Publications

Extensive seeded epitaxial growth of crystalline Si over SiO₂ was achieved by an oscillatory regrowth method applied to rectangular Si pads recessed into a thick SiO₂ film. Narrow (≃5 μm) via holes linked the pads with the bulk (100) Si substrate. Oriented single crystals propagated as far as 500 μm from the seeding area, following the long term advance of a scanned focused laser beam.

Conversion And Matched Filter Approximations For Serial Minimum-Shift Keyed Modulation, Carl R. Ryan, James H. Stilwell, Rodger E. Ziemer

Electrical and Computer Engineering Faculty Research & Creative Works

Serial minimum-shift keyed (MSK) modulation, a technique for generating and detecting MSK using series filtering, is ideally suited for high data rate applications provided the required conversion and matched filters can be closely approximated. Low-pass implementations of these filters as parallel inphase-and quadrature-mixer structures are characterized in this paper in terms of signal-to-noise ratio (SNR) degradation from ideal and envelope deviation. Several hardware implementation techniques utilizing microwave devices or lumped elements are presented. Optimization of parameter values results in realizations whose SNR degradation is less than 0.5 dB at error probabilities of 10-6. © 1982 IEEE

An Optimal Control Law By Eigenvalue Assignment For Improved Dynamic Stability In Power Systems, A. B.R. Kumar, Earl F. Richards

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

On The Uniqueness Of Solution Of Magnetostatic Vector‐Potential Problems By Three‐Dimensional Finite‐Element Methods, O. A. Mohammed, W. A. Davis, B. D. Popovic, T. W. Nehl, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

In this paper, particular attention is paid to the impact of finite‐element approximation on uniqueness and to approximations implicit in finite element formulations from the uniqueness requirements standpoint. It is also shown that the flux density is unique without qualifications. The theoretical and numerical uniqueness of the magnetic vector potential in three‐dimensional problems is also given. This analysis is restricted to linear, isotropic media with Dirichlet Boundary conditions. As an interesting consequence of this analysis it is shown that, under usual conditions adopted in obtaining three‐dimensional finite‐element solutions, it is not necessary to specify div Ā in order that Ā …

Electrical And Structural Properties Of P-N Junctions In Cw Laser Annealed Silicon, M. Maier, D. Bimberg, G. Fernholz, H. Baumgart, F. Phillipp

Electrical & Computer Engineering Faculty Publications

Depth profiles of the electrical quality of ion implanted and cw laser annealed p-n junctions in silicon are obtained for the first time by secondary ion mass spectroscopy. A comparison with the crystallographic properties of the surface and the junction as observed by Nomarski optical microscopy as well as cross-sectional and plan view transmission electron microscopy is made. Samples containing slip dislocations show better insulation and a lower reverse bias current across the p-n junction as compared to samples with a perfect surface in agreement with current-voltage characteristics. Small dislocation loops located at the junction are found to degrade the …