Engineering Commons^™

Estimation Approach To Locating Buried Geological Interfaces, A. Omar, A. Addeeb, C. Slivinsky, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

The objective of the estimation work described in this paper is to improve algorithms for reconstructing the geometric configuration of acoustic reflecting surfaces. The conventional migration method of locating these surfaces is reviewed. A recent imaging condition which is closely related to the boundary condition at the geological interface is then described. This later procedure results in two outputs. One can be used to reconstruct the shape of the unknown acoustic reflector, while the second output estimates the acoustic wavespeed on the transmission side of the boundary. When noise is present in the reflected signal, the performance of the method …

A Limitation To The Use Of A Constructive Approach In The Stability Analysis Of Fixed-Point Digital Controllers, Kelvin T. Erickson

Electrical and Computer Engineering Faculty Research & Creative Works

A limitation to the application of a constructive algorithm to the stability analysis of fixed-point digital controllers is demonstrated by an example. The particular system analyzed consists of a fixed-point PI digital controller regulating a first-order process.

Maximum-Likelihood Estimation Of Time-Varying Delay-Part I, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

This Paper Presents, for the First Time, the Exact Theoretical Solution to the Problem of Maximum-Likelihood (ML) Estimation of Time-Varying Delay d(t) between a Random Signal s(t) Received at One Point in the Presence of Uncorrelated Noise, and the Time-Delayed, Scaled Version as(t - d(t)) of that Signal Received at Another Point in the Presence of Uncorrelated Noise. the Signal is Modeled as a Sample Function of a Nonstationary Gaussian Random Process and the Observation Interval is Arbitrary. the Analysis of This Paper Represents a Generalization of that of Knapp and Carter [1], Who Derived the ML Estimator for the …

A New Approach To Signal Registration With The Emphasis On Variable Time Delay Estimation, Mohamad Namazi, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

Signal Registration is Concerned with the Problem of Estimating a Varying Displacement between Two Random Processes. We Approach Signal Registration Here as a Recursive Demodulation Problem in Which the Recursion is between Signal Estimations and Displacement Estimation. Special Attention is Given to the Problem of Estimating a Variable Time Delay. Thus, We Present New Algorithms for Estimating D(T) from Received Processes:

r₁(t) = s(t) + n₁(t)

R₂(t) = s(t - D(t)) +n₂(t)

Where s [Formula Omitted] is Signal and n₁ (•) and n₂ (•) Are Noise. Simulation Results Are Presented …

Bias‐Dependent Photoresponse Of P+In Gaas/Alas/Gaas Diodes, Michael R. Melloch, C. P. Mcmahon, Mark S. Lundstrom, J. A. Cooper Jr., Q D. Qian, S. Bandyopadhyay

Department of Electrical and Computer Engineering Faculty Publications

We report photocollection efficiency measurements of p + in GaAs! AIAs!GaAs diodes fabricated on films grown by molecular beam epitaxy, Both the zero-bias and bias-dependent photocollection characteristics can be explained by assuming that the band discontinuity between AlAs and GaAs is mostly accommodated i.n the valence band.

Importance Of Space-Charge Effects In Resonant Tunneling Devices, M. Cahay, M. Mclennan, D. Datta, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

The consideration of space charge in the analysis of resonant tunneling devices leads to a substantial modification of the current-voltage relationship. The region of negative differential resistance (NDR) is shifted to a higher voltage, and broadened along the voltage axis. Moreover, the peak value of current prior to NDR is reduced, leading to a reduction in the predicted peak-to-valley ratio. An approach is presented to include space-charge effects, and a recently fabricated GaAs-Alx Gal _ x As structure is analyzed, to underscore the importance of a self-consistent electrostatic potential in theoretical calculations.

Recombination-Current Suppression In Gaas P-N Junctions Grown On Algaas Buffer Layers By Molecular-Beam Epitaxy, D. P. Rancour, M. R. Melloch, R. F. Pierret, Mark S. Lundstrom, M. E. Klausmeier-Brown, C. S. Kyono

Department of Electrical and Computer Engineering Faculty Publications

n+pp+GaAs and n+pP+ GaAs/GaAs/Al0.3Ga0.7As mesa diodes have been fabricated from films grown by molecular‐beam epitaxy. The diodes made from films employing an AlGaAs buffer layer show marked improvements (a factor of 5 reduction) in recombination current densities. Deep level transient spectroscopy measurements moreover indicate that deep level concentrations are reduced by the AlGaAs buffer.

Computer Simulation Of Dynamic Systems, Charles G. Smith

Retrospective Theses and Dissertations

Computer simulation of a control system is a valuable tool in design or performance evaluation. This is especially true when non-linear elements cannot be ignored and must be included within the model. A general purpose block diagram oriented simulation program will be developed which can utilize continuous, discrete and non-linear building blocks. The software tool will be demonstrated by means of an example.

Compiling Unit Clauses For The Warren Abstract Machine, George D. Herbert

UNF Graduate Theses and Dissertations

This thesis describes the design, development, and installation of a computer program which compiles unit clauses generated in a Prolog-based environment at Argonne National Laboratories into Warren Abstract Machine (WAM) code. The program enhances the capabilities of the environment by providing rapid unification and subsumption tests for the very significant class of unit clauses. This should improve performance substantially for large programs that generate and use many unit clauses.

Comment On "Orientation, Alignment, And Hyperfine Effects On Dissociation Of Diatomic Molecules To Open Shell Atoms", Mark D. Havey, Linda L. Vahala

Electrical & Computer Engineering Faculty Publications

A recent paper in this journal [Y. B. Band e t a l., J. Chem. Phys. 8 4, 3762 (1986)] reported parameters describing orientation and alignment produced, in an axial recoil limit, by one photondissociation of diatomic molecules. Reported also were values, applicable to the resonance transitions of the alkali atoms, for orientation and alignment depolarization coefficients. Most of the numerical values reported for the coefficients were incorrect, in some cases by as much as a factor of 2. We report a tabulation of correct depolarization coefficients applicable to the resonance transitions of common alkali isotopes. Further, the coefficients …

Simultaneous System Identification And Decision-Directed Detection And Estimation Of Jump Inputs To Linear Systems, Wynn C. Stirling

Faculty Publications

A decision-directed approach is presented for analyzing linear systems with unknown jump inputs. The system model parameters are estimated using a Kalman filter, and an empirical Bayes detection procedure is introduced to set the detector parameters, resulting in a decision-directed generalized likelihood ratio test coupled with recursive system parameter estimation. Monte Carlo results are presented to validate the performance of the algorithm.

Parallel Approximate String Matching Applied To Occluded Object Recognition, David Smith

Dissertations and Theses

This thesis develops an algorithm for approximate string matching and applies it to the problem of partially occluded object recognition. The algorithm measures the similarity of differing strings by scanning for matching substrings between strings. The length and number of matching substrings determines the amount of similarity. A classification algorithm is developed using the approximate string matching algorithm for the identification and classification of objects. A previously developed method of shape description is used for object representation.

Threshold Characteristics Of Multimode Laser Oscillators, Mehdi Khoshnevissan

Dissertations and Theses

The threshold characteristics of multimode laser oscillators are considered in detail, and a new model is given for semiconductor diode lasers. Analytical expressions and numerical solutions are obtained for mode amplitudes, and over-all spectral characteristics of lasers operating above and below threshold. The theoretical results are i n agreement with experimental data. The band-ta-band absorption is included in the model and i t ' s effect is studied on the mixed broadening.

Numerical Solutions Of Continuous Wave Beam In Nonlinear Media, Jeffrey Huang

Dissertations and Theses

Deformation of a Gaussian beam is observed when it propagates through a plasma. Self-focusing of the beam may be observed when the intensity of the laser increases the index of refraction of plasma gas.

Due to the difficulties in solving the nonlinear partial differential equation in Maxwell's wave equation, a numerical technique has been developed in favor of the traditional analytical method. Result of numerical solution shows consistency with the analytical method. This further suggests the validity of the numerical technique employed.

A three dimensional graphics package was used to depict the numerical data obtained from the calculation. Plots from …

The Design Of A Resonant Post Waveguide Filter, Ramjee Prasad

Tanzania Journal of Engineering and Technology (TJET)

A seven stage, quarter-wave coupled, single post, resonant cavity type waveguide filter has been studied. The posts are placed according to the Tchebyscheff distribution. The filter is designed and fabricated to meet the following specifications: Centre frequency: 9.31 GHz, Number of stages = 7, 3-dB bandwidth = 300 Mhz, Ripple tolerance in the passband = 0.5 dB. The frequency behaviour of this filter has been experimentally studied and is in close agreement with the specifications.

Gain Margin And Phase Margin Interrelationships, M Luhanga

Tanzania Journal of Engineering and Technology (TJET)

The gain margin and the phase margin Of a control SY Stem are important parameters in the determination of the relative stability of control system. In this paper We derive general interrelationships between these parameters.

Electric Power Transmission & Purchases : Report Of A Study By The Joint Standing Committee On Utilities, 112th Maine Legislature, Maine. Legislature. Joint Standing Committee On Utilities

Maine Collection

Electric Power Transmission & Purchases : Report Of a Study By the Joint Standing Committee on Utilities, 112th Maine Legislature

Maine Legislature. Joint Standing Committee on Utilities.

Augusta, Maine (December 2, 1986).

Contents: Introduction / Issues & Recommendations / Review of 1986 Legislation / Maine's Electric Power Picture / Technical Analysis of Transmission & Wheeling / Economic Implications of Transmission & Wheeling /. Legals Analysis of Transmission & Wheeling / Proposed Legislation / Appendices / Tables & Figures

Polarizing Beam Splitters For Infrared And Millimeter Waves Using Single-Layer-Coated Dielectric Slab Or Unbacked Films, R. M.A. Azzam

Electrical Engineering Faculty Publications

No abstract provided.

Response Of The Rotating-Detector Ellipsometer To Incident Partially Polarized Light, R. M.A. Azzam

Electrical Engineering Faculty Publications

No abstract provided.

Metal Waveguide Modeling Of Tapered Quadratic Index Media, Lee W. Casperson, Bahram Zandi

Electrical and Computer Engineering Faculty Publications and Presentations

The basic electromagnetic properties of tapered graded index fibers are equivalent to the properties of a class of concave metallic waveguides. Although useful in their own right, such metal waveguides also provide a straightforward and inexpensive means for studying the characteristics of more complicated tapered media.

Thin-Film Beam Splitter That Reflects Light As A Half-Wave Retarder And Transmits It Without Change Of Polarization: Application To A Michelson Interferometer, R. M.A. Azzam

Electrical Engineering Faculty Publications

The refractive index n₁ of a transparent layer of quarter-wave optical thickness coating a transparent substrate of refractive index n₂ can be chosen to produce half-wave retardation (HWR) in reflection and no change of polarization in refraction at any angle of incidence ø. The function n₁(ø, n₂), and the associated polarization-independent reflectance of the film-substrate system R(ø, n₂) are determined. Such a coated surface can be used as a beam splitter with excellent characteristics (e.g., split fractions that do not depend on source polarization, a split beam whose polarization is identical …

Editing Templates: A User Interface Generation Tool, Dan R. Olsen Jr.

Faculty Publications

This article discusses a basic architecture for a user interface management system and the problem of updating a display in response to interactive commands. The basic architecture is then extended to include basic editing and browsing processes on arbitrary data structures. Editing templates are presented as a technique embodying the entire manipulation process for a particular data structure/data display combination. In conjuction with the user interface management system, Such templates are able to automatically provide a majority of the code required in an interactive applicaton.

An Investigation Of Overvoltage Effects On A Gas-Blown Spark Gap, Michael Steven Mazzola

Electrical & Computer Engineering Theses & Dissertations

This experimental investigation addresses the anomalous overvoltage breakdown and subsequent recovery characteristics observed in gas-blown spark gaps. Previous investigations have reported a two-stage recovery process in self-break, pulse-charged, gas-blown spark gape in which the spark gap recovers first to an intermediate breakdown strength before recovering to the undisturbed breakdown voltage. The recovery process has been explained in terms of two different characteristic times. The first is that required to obtain initial recovery in which the spark gap regains its intrinsic breakdown strength. The second time is that required to obtain final recovery in which the pulse-charged spark gap regains the …

A Frequency Domain Digital Signal Processor For Laser Velocimeter Systems, Andreas Evangelos Savvakis

Electrical & Computer Engineering Theses & Dissertations

A new signal processor for laser velocimeter systems is proposed. The proposed processor incorporates automatic initialization, real time operation, and can efficiently process input signals comprised of as low as 150 photons, with mean oscillation frequency up to 100 MHZ, and input turbulence from 0 to 20%. A bank of digital bandpass filters is employed for the energy spectrum estimation of the input signal. A deterministic model is developed to describe the relationship between the filter output energies and the input signal parameters. The input frequency is estimated by linearly weighting the filter output energies. A spline function approximation approach …

Wind Streamline Ambiguity Removal Of Microwave Scatterometer Data, Hans W. Zaepfel

Electrical & Computer Engineering Theses & Dissertations

There is a class of satellite microwave scatterometers that return oceanographic information which includes wind vectors with directional ambiguity. The first part of the ambiguity removal process is to reduce the data to a directional ambiguity of 180°. This thesis shows that wind direction change contains the information required for streamline ambiguity removal and that syntactic pattern recognition techniques can be used to locate the areas of wind direction change. Spreading the information along the areas of wind direction change results in the removal of the streamline ambiguity. The algorithm is implemented and the results are presented showing that it …

Multi-H Continuous Phase Modulation : Its Properties And Analysis, Jyung-Cheng Chen

Theses

Multi-h CPM, a generalization of CPFSK and also one of the so-called Combined Modulation and Coding schemes, is useful in digital communication systems where both the bandwidth and power are constrained. The increased signal processing complexity, which can be viewed as the third communication resource, is used to trade for both power and bandwidth, and to approach the error-free communication promised by Shannon's theorem.

The transmitted multi-h CPM signal carries a coded sequence of continuous phase changes; the possible phase states form a cylindrical trellis in phase and time, in which the modulation indices are reused in a cyclical fashion. …

Logic Simulation And Methodologies For Design For Testability, Ravi Shankar Prasad Mallampalli

Theses

This thesis describes the method used for developing the standard TTL blocks using the logic simulator SPLICE1. It also gives a comprehensive overview of methods which can be used for designing a circuit which is testable. A format called Electronic Design Interchange Format (EDIF) is also described as a tool which can be used for transporting design data in the VLSI indgstry.

Focused Acoustic Wave (Faw) Channelizer, Dennis R. Pape, Andrew M. Bardos, Marc H. Popek, Manhar L. Shah

Electrical Engineering and Computer Science Faculty Publications

The architecture, operation, and performance of a new integrated acoustic RF channelizer are described. The all- acoustic device uses a phased array piezoelectric transducer to generate frequency dispersed bulk acoustic waves over a 500 MHz bandwidth. The waves are focused onto a 25 channel receiver electrode array by a cylindrical reflector formed on the opposing surface of the device. This channelizer has the potential of providing higher dynamic range than competing technologies. © 1986 SPIE.

The Modeling Of A Self-Oscillating Dc-To-Dc Converter, Frank Andrew Linkowsky

Theses

This thesis develops a model of a nonlinear self oscillating current-or-voltage step-up dc-to-dc converter. Expressions are given that predict the operation of the converter in the time domain and in the state plane. To verify these expressions, a large signal computer simulation technique [1] is used to compare theoretical results with actual measurements. This type of simulation allows a nonlinear switching converter to be modeled with a series of piecewise-linear operating intervals. The resulting waveforms predicted by the developed model show close agreement with waveforms found in the laboratory. Therefore, the model represents a powerful tool that may be used …

Gallium Film Formation By Ion Cluster Beam Deposition, Te-Chuan Hsu

Theses

Gallium thin films were deposited by Ion Cluster Beam (ICB) from pure gallium. This research had two objectives: to develop a practical method of crucible heating to generate gallium clusters; and to investigate the influence of ICB system parameters on the formation of clusters and film properties. An electron-bombardment crucible heater with a novel construction was designed. The top section of the carbon crucible was kept at a higher temperature than the middle section to prevent clogging of the nozzle and " spitting " phenomena which were found to occur with the conventional design. Crucible temperatures up to about 1360°C …