Engineering Commons^™

Symmetry-Forbidden Resonant Raman Scattering In Cu2O, S. P. S. Porto, P. F. Williams

P. F. (Paul Frazer) Williams Publications

We have observed resonant Raman scattering from the two longitudinal branches of the Raman-forbidden F_{1u modes of Cu2O. The agreement between our measured scattering cross section as a function of excitation frequency and a calculated cross section which assumes an intraband Frohlich electron-phonon interaction is good. This represents a quantitative confirmation of the resonant-Raman-scattering theory proposed by Martin.}

An Historical Review Of Oil Spills Along The Maine Coast 1953-1973, Edward H. Shenton

Maine Collection

An Historical Review of Oil Spills Along the Maine Coast 1953-1973

by Edward H. Shenton

Prepared for The Maine State Planning Office, Coastal Planning Group and The Research Institute of the Gulf of Maine (TRIGOM), August, 1973.

TRIGOM Publication No. 3

Contents: Introduction / A Chronology of Significant Oil Spills / A Summary of Biological Impacts / Spill Statistics / Discussion of Results / Conclusions of the Study / Recommendations for Future Research / Appendices

A New Sampling Theorem For Causal (Non-Bandlimited) Functions., Alan Baker Campbell

Electrical and Computer Engineering ETDs

It is shown in this work that whereas any causal function (i.e., any function with a definite starting point) is non-bandlimited and thus would be thought to require an infinite sample rate, there is an infinite class of causal functions (identified as "regionally bandlimited functions" (r.b.f.'s)) for which a finite sample rate is adequate.

Fast Neutron Effects On Time Delay Occuring In Gallium Arsenide Laser Diodes., James Owen Schroeder

Electrical and Computer Engineering ETDs

A study has been made on the effects of fast neutron irradiation on time delay occurring in diffused GaAs laser diodes operating at 77° K and 300° K. Measurements were performed at 300° K prior to irradiation and thence after successive exposure to neutron irradiation to a maximum of about 1.2 x 10^14 nvt (>10 KeV). At 77° K, measurements were limited to a pre-irradiation characterization and a characterization after the final irradiation. A double acceptor model is used to account for the observed changes in the delay characteristics as a result of both temperature changes and neutron irradiation. …

An Experimental Study Of Ultrahigh Fluence Oxygen Ion Implantation In Silicon, Charles Burton Fite

Electrical and Computer Engineering ETDs

An investigation was made to determine the feasibility of using ultrahigh fluences of implanted oxygen ions to create a usable oxide layer on silicon for device applications. Previous studies have indicated that SiO₂ can indeed be formed in this manner, but very little work has been reported on the electrical and structural nature of the resulting oxide-silicon interface. Six implants with fluences ranging from 1.25 x 10¹⁷ to 1 x 10¹⁸ (O₂)⁺ /cm² were performed into p-type silicon wafers. The implanted material was then studied to determine how the variables of anneal time, …

Generalized Feedback Shift Register Pseudorandom Number Algorithm, Theodore Gyle Lewis, W. H. Payne

Electrical and Computer Engineering Faculty Research & Creative Works

The generalized feedback shift register pseudorandom number algorithm has several advantages over all other pseudorandom number generators. These advantages are: (1) it produces multidimensional pseudorandom numbers; (2) it has an arbitrarily long period independent of the word size of the computer on which it is implemented; (3) it is faster than other pseudorandom number generators; (4) the "same" floating-point pseudorandom number sequence is obtained on any machine, that is, the high order mantissa bits of each pseudorandom number agree on all machines— examples are given for IBM 360, Sperry-Rand-Univac 1108, Control Data 6000, and Hewlett-Packard 2100 series computers; (5) it …

Adaptive, Differential Pulse-Code Modulation For Speech Processing, Peter Cummiskey

Dissertations

The objective of the research reported here is the design of efficient speech coders that can easily be implemented in integrated circuit hardware. Companding techniques like those introduced by M. R. Winkler, J. A. Greefkes, F. DeJager, A. Tomozawa and H. Kaneko were explored along with a large body of theory concerning the application of linear prediction to speech coding.

The best features of the speech signal to be measured and coded are the overall amplitude, the resonant frequencies and dampings of the vocal cavity and the fundamental frequency of the vocal cord oscillations. Adaptive quantization was used to track …

An Intensity-Dependent Filter, James M. Thorne, Thomas R. Loree, George Mccall

Faculty Publications

It is useful in optically driven Kerr-cell shutters and other laser applications to have intense pulses with extremely low light levels between pulses. We describe here a device that accomplishes this objective external to the laser cavity.

Digital Computer Solution Of Electromagnetic Transients In Large Power Systems, Bijan Navidbakhsh

Dissertations and Theses

This thesis is an introduction to the solution of electromagnetic transients by a combination of the Bergeran method of characteristics and the application of trapezoidal rule of integration.

Three test examples solved by digital computer illustrate the step by step solution and computer programming.

To compare this method with the Laplace transformation technique, a test problem solved by both methods and also digital computer is illustrated. In conclusion, the advantages and disadvantages of both methods are compared.

The Random Sequence Closing Control System, Henri Bernard Joyaux

Dissertations and Theses

This thesis describes a digital control system used by the Network Analog Group of the Bonneville Power Administration. This system, the Random Sequence Closing Control System, provides automatic control for a special purpose analog computer used in the study of switching surge over voltages on power transmission lines. This system, which uses pseudorandom data, has made it feasible to analyze switching surge phenomena on a statistical basis.

Resonant Raman Scattering From Iodine: Spectral Changes With Excitation Frequency, P. F. Williams, D. L. Rousseau

P. F. (Paul Frazer) Williams Publications

We have recorded high-resolution resonant Raman spectra of molecular iodine which show very pronounced systematic spectral band-shape variations with incident laser frequency. This frequency dependence and the presence of the multiple overtones in resonant Raman scattering from iodine may be explained by a theory in which the scattering intensity depends on Franck-Condon overlap integrals. We have obtained semiquantitative agreement between the observed spectra and spectra calculated from this theory.

State Estimation In Discrete-Time Linear Systems With Quadratic Form Observers, James Parish Shipley Jr.

Electrical and Computer Engineering ETDs

The problem considered in this dissertation is that of estimating the state of a system with a linear plant equation but having a measurement function which is a quadratic form in the state. It is first demonstrated by constructive proof that the problem has a solution if the controls have large enough magnitude, and some requirements on the minimum size of the control are discussed.

Three algorithms for estimating the state are obtained, one using the technique of maximum likelihood, the other two utilizing a more general Bayesian approach. In addition, a first-order approximate conditional mean filter is included for …

Electrical Parameter Correlations For Radiation Hardness Assurance Of Operational Amplifiers, John L. Mullis

Electrical and Computer Engineering ETDs

In the manufacture of integrated circuits, a consider­able amount of attention is given to controlling fabrication processes. This is required if high production yield and consistent quality are to be obtained. In addition to moni­toring critical parameters which are influenced by variables in processing, the packaged circuits undergo a variety of tests to determine whether they meet the desired electrical and environmental quality specifications. The problem of quality assurance is accepted and treated as an essential part of the production cycle.

Dosimetry For High Intensity, 2 Mev Radiation., Clifford Ledth Schroeder

Electrical and Computer Engineering ETDs

The purpose of this effort is to evaluate several types of dosimeters being used with the 2-MeV flash X-ray facilities at The University of New Mexico and the Air Force Weapons Laboratory (AFWL). The types include lithium fluoride and calcium fluoride thermaluminescent dosimeters (TLD's), thin foil calorimeters, p-i-n diodes, cobalt glass chips, and #25 purple Cinemoid. The evaluation includes a comparison of dose measurements, repeatability, and useful ranges. This report describes fundamental physical mechanisms by which photons and high energy electrons interact with matter, the physical mechanisms of different dosimeters, and techniques for using the dosimeters. The calcium fluoride TLD's …

Trajectories Describing The Evolution Of Polarized Light In Homogeneous Anisotropic Media And Liquid Crystals, Rasheed M.A. Azzam, N. M. Bashara, B. E. Merrill

Electrical Engineering Faculty Publications

Trajectories are given that describe the evolution of the ellipse of polarization in the complex plane for light propagating in a homogeneous anisotropic medium and along the helical axis of a cholesteric liquid crystal. For the general homogeneous anisotropic medium that exhibits combined birefringence and dichroism the trajectory is a spiral that converges to the low-absorption eigenpolarization. For pure birefringence the trajectory becomes a complete circle that encloses one eigenpolarization, whereas for pure dichroism the trajectory becomes an arc of a circle that ends at the low-absorption eigenstate. The case of a cholesteric (or twisted nematic) liquid crystal leads to …

Inertial Navigation Performance Improvement Realized By The Technique Of Interrupted Alignment, Ralph E. Herndon

Masters Theses

"Present on-aircraft ground alignment gyro bias methods can basically be categorized as (1) periodic maintenance performed by the ground crew, (2) pre-flight calibration requiring a two-position gyro compass alignment or (3) optimal filter estimation of the north gyro bias error.

This thesis discussion presents an interrupted alignment method that allows adequate level axes gyro bias correction without the restrictions associated with a conventional two-position gyrocompass alignment (i.e., a minimum time for bias calibration on a steady aircraft). The interrupted alignment technique allows the pilot to select the navigate mode at any point during gyrocompass and reselect the align mode at …

A Thin Film Evaporator Rate Controller, Daniel Robert Kasterlein

Masters Theses

"A circuit is described which is used to control the evaporation rate of material from a resistance heated boat or electron beam evaporator. The rate controller is used in conjunction with a quartz crystal thickness monitor in a vacuum evaporator"--Abstract, page ii.

Tilt-Table Alignment For Inertial-Platform Maintenance Without A Surveyed Site, Gordon E. Carlson, Max E. Bott

Electrical and Computer Engineering Faculty Research & Creative Works

A method for aligning the rotary tilt table for an inertial-platform maintenance facility without surveying the site is analyzed and evaluated. The method utilizes multiple measurements of the tilt-table azimuth alignment error with different inertial platforms to determine a best estimate of the alignment error. Error analysis indicates that useful facility performance can be obtained with only a small number of measurements. The tilt-table alignment accuracy can be improved as more measurements of the alignment error are made during normal facility operation. © 1973, IEEE. All rights reserved.

The Effects Of Ionizing Radiation On Gallium Arsenide Phosphide Metal-Insulator-Semiconductor Structures, Gordon James Kuhlmann

Electrical and Computer Engineering ETDs

MIS capacitors were fabricated on n-type GaAs 0.5 p 0.5 using a thermally grown chromium-doped insulator and chromium gate electrode. The fabrication procedures which lead to stable devices are described. The nature of the composite insulator, as well as that of a disordered layer of GaAs 0.5 P 0.5 underneath the insulator are discussed and related to observed electrical characteristics.

Flatband voltages for the capacitors subsequent to device fabrication ranged from -2.5 to -5 volts, corresponding to surface charge densities of 3.1 x 10 11 cm-2 to 4.3 x 10 11 cm-2. Fast interface state densities at flatband varied from …

Applications Of Frequency Domain Stability Criteria In The Design Of Nonlinear Feedback Systems, Allen Joseph Rushing

Doctoral Dissertations

"The Popov criterion for absolute stability of nonlinear feedback systems is applied to several example problems. Model transformations such as pole shifting and zero shifting extend the class of systems to which the criterion applies. Extensions of the criterion having simple graphical interpretations yield stronger results for systems with constant monotonic slope-bounded nonlinearities. Additional extensions lacking simple graphical interpretations in the complex plane are also demonstrated by example.

Stability throughout a region in parameter space is discussed, and the Kalman conjecture is verified for a new class of systems. The Popov criterion is also used to prove BIBO stability, process …

Considerations In The Design Of A Network Of Minicomputers, Hardy J. Pottinger

Doctoral Dissertations

"The advantages of a network consisting of a number of minicomputers coupled to a large time shared computer are described. This type of network is very useful in the areas of data acquisition, real time control of experiments, and front-end processing for computer graphics.

Problems associated with the development of a network of this type, various possible solutions, and the trade-offs involved are presented. These problems are classified into two categories: the interface between the network and the central computing facility, and the interface between the remote sites and the rest of the network.

The design constraints, rationale, and implementation …

On The Method Of Stationary Phase, Byungkyu Park

Electrical and Computer Engineering Faculty Research & Creative Works

The method of stationary phase (MSP), which is an asymptotic method of integration, nevertheless yields general (nonasymptotic) results when applied to certain integrals involving the spherical function. In such cases one may drop the requirement of far-field or high frequency from the results. Copyright © 1973 by The Institute of Electrical and Electronics Engineers. Inc.

An Improved Single Flight Technique For Radar Stereo, Gordon E. Carlson

Electrical and Computer Engineering Faculty Research & Creative Works

An improved technique for obtaining stereo radar image pairs is described. The technique uses a unique combination of two different radar beam pattern characteristics. The resulting stereo radar images are illuminated from very nearly the same aircraft position which results in radar shadow and back-scatter characteristics which are very similar and in improved image registration possibilities. The reduction in illumination angle and aircraft position differences is shown to be nearly an order of magnitude or more when compared with a previously proposed single flight technique which used two vertical fan beam patterns at different azimuth angles. As a related sidelight …

Performance Degradation Due To Specular Multipath Intersymbol Interference, G. H. Smith, David R. Cunningham, Rodger E. Ziemer

Electrical and Computer Engineering Faculty Research & Creative Works

Plots of performance degradation are used to compare the effects of fading and intersymbol interference in a two-component specular multipath digital communications channel. Similar plots are then used to compare two practical receivers designed to combat the interference. Degradation plots are shown to allow easy identification of each receiver's range of usefulness, as well as identification of variance bounds demanded of channel parameter estimates which the receivers require. Copyright © 1973 by The Institute of Electrical and Electronics Engineers, Inc.

Numerical Calculation Of The Currents In Bent Wire Antennas, Min Ho Kang

Masters Theses

"The current distribution for bent dipole antennas is numerically calculated by using a digital computer. A delta-gap at the center is assumed for the drive. Several different bend-angles are considered including the cases of the straight wire and the inverted-L. The total length of the wire considered is λ/2 while the ratio of the bent portion over the vertical portion is varied. The method of solution is based on Mei's integral equation and the method of moments. The use of Mei's integral equation eliminates the need for the application of the boundary condition at the point of bending. For …

Analysis Of A Microcircuit, Distributed Parameter Network, Which Considers Series Inductance And Shunt Conductance, Arun Jayantilal Shah

Theses and Dissertations

In this work analysis of distributed microcircuit is carried out including effects of series inductance and shunt conductance. General solution for voltage and current are obtained in terms of arbitrary constants which are to be determined by input and output conditions. Terminal voltages and terminal currents are expressed by Indefinite Admittance Matrix and port voltage, and port currents are expressed by Indefinite Impedance Matrix. Illustrative example is solved using indefinite matrix configuration and proper boundary conditions.

Decision-Directed Detector For Overlapping Pcm/Nrz Signals, Cheng Wang, Thomas L. Noack

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A decision-directed (DD) technique for the detection of overlapping PCM/NRZ signals in the presence of white Gaussian noise is investigated. The performance of the DD detector is represented by probability of error PE versus input signal-to-noise ratio (SNR). To examine how much improvement in performance can be achieved with this technique, PE's with and without DD feedback are evaluated in parallel. Further, analytical results are compared with those found by Monte Carlo simulations. The results are shown in good agreement. © 1973, IEEE. All rights reserved.

Implementation Of Recursive Algorithms For Delay-Time Estimation Using The Fast Walsh Transform, Donald Robert Nelson

Doctoral Dissertations

"Use of the fast Walsh transform to resolve noisy signals into Walsh function series to digitally implement maximum-likelihood parameter estimators for real-time use is investigated. Realization of estimators which seek a null in the derivative of the log-likelihood function, instead of direct maximization, results in feedback algorithms which yield considerable savings in computation time and storage. Performance of these feedback delay-estimation algorithms is characterized in terms of mean-squared error (MSE) and response to a delay step by Monte Carlo simulation. The effect of changing the number of points in the transform on the MSE is also investigated. Hard limiting of …

Parameter Identification Applied To Linear Quadratic Differential Games, John D. Corrigan

Doctoral Dissertations

"A two player zero-sum linear quadratic differential game is investigated for the case in which one of the players has incomplete a priori knowledge of the parameters of his opponent's dynamic system. This incomplete system parameter information game is shown to be playable since the ignorant player can make limiting estimates of the unknown parameters from the relative controllability condition for the game. Performance from the ignorant player's point of view is suboptimal.

It is also shown that parameter identification techniques can be applied by the ignorant player in order to directly identify the smart player's closed-loop parameters in the …

A Multivariable Sampled-Data Model Of An Automobile Driver, Jose A. Bermudez

Masters Theses

"In this thesis, a multivariable system model of driver performance in the basic driving tasks is presented. The driver model described acts as a serial-process, priority-accessed, time-sharing computer. This model processes the input or output task which currently possesses the highest priority. Input tasks are represented by continuous signals sampled intermittently according to priority laws. Output tasks are modeled as simple analog processes operating on the last few intermittently generated output controls. An individual priority rule is constructed for each input and output task.

The performance of the driver in the lateral control task involves a feedforward pattern which is …