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Full-Text Articles in Engineering

A Multiple Coupled Microstrip Transmission Line Model For High-Speed Vlsi Interconnect Simulation, Lawrence Stevan Uzelac Dec 1991

A Multiple Coupled Microstrip Transmission Line Model For High-Speed Vlsi Interconnect Simulation, Lawrence Stevan Uzelac

Dissertations and Theses

A model is presented which incorporates the advantages of a mixed mode simulation to characterize transmission line behavior in multiple coupled Transmission line systems. The model is intended for use by digital circuit designers who wish to be able to obtain accurate transmission line behavior for complex digital systems for which continuous time simulation tools such as SPICE would time prohibitive. The model uses a transverse electromagnetic wave approximation to obtain solutions to the basic transmission line equations. A modal analysis technique is used to solve for the attenuation and propagation constants for the transmission lines. Modal analysis done in ...


Spectral And Spatial Quantum Efficiency Of Algaas/Gaas And Ingaas/Inp Pin Photodiodes, Steven Alan Tabor Dec 1991

Spectral And Spatial Quantum Efficiency Of Algaas/Gaas And Ingaas/Inp Pin Photodiodes, Steven Alan Tabor

Dissertations and Theses

This thesis reports a novel system capable of testing both the spectral responsivity and the spatial quantum efficiency uniformity of heterostructure photodiodes using optical fiber coupled radiation. Testing was performed to confirm device specifications. This study undertakes to quantify the spectral bandwidth of an AlGaAs I GaAs double heterostructure photodiode and two InGaAs I InP double heterostructure PIN photodiodes at D.C., through the use of spatial scanning. The spatial scanning was done using lasers at 670 nm, 780 nm, 848 nm, 1300 nm, and 1550 nm, coupled through singlemode optical fiber. The AlGaAs I GaAs material system covers the ...


Stochastic Hydrologic Modeling In Real Time Using A Deterministic Model (Streamflow Synthesis And Reservoir Regulation Model), Time Series Model, And Kalman Filter, Philip Kwok Fan Tang Nov 1991

Stochastic Hydrologic Modeling In Real Time Using A Deterministic Model (Streamflow Synthesis And Reservoir Regulation Model), Time Series Model, And Kalman Filter, Philip Kwok Fan Tang

Dissertations and Theses

The basic concepts of hydrologic forecasting using the Streamflow Synthesis And Reservoir Regulation Model of the U.S. Army Corps of Engineers, auto-regressive-moving-average time series models (including Greens' functions, inverse functions, auto covariance Functions, and model estimation algorithm), and the Kalman filter (including state space modeling, system uncertainty, and filter algorithm), were explored. A computational experiment was conducted in which the Kalman filter was applied to update Mehama local basin model (Mehama is a 227 sq. miles watershed located on the North Santiam River near Salem, Oregon.), a typical SSARR basin model, to streamflow measurements as they became available in ...


Limits Of Limit Equilibrium And Finite Element Techniques Applied To Cracked Debris Dams On Collapsing Foundations, Stanley Soliday Jr. Jan 1991

Limits Of Limit Equilibrium And Finite Element Techniques Applied To Cracked Debris Dams On Collapsing Foundations, Stanley Soliday Jr.

Dissertations and Theses

Limits of slope stability, limit equilibrium methods, and of the finite element code FEADAM are reached in the application of these methods to the problem of cracked dams constructed on collapsing soils.


Parplum : A System For Evaluating Parallel Program Optimization Methods, Jingsong Fu Jan 1991

Parplum : A System For Evaluating Parallel Program Optimization Methods, Jingsong Fu

Dissertations and Theses

The diversity of application programs and parallel architectures makes the mapping problem complicated and hard to evaluate. The quality of mapping is machine and application dependent and varies due to inaccurate values of application and architecture characteristics.

A system for developing, applying and evaluating mappings must have four characteristics: (1) Simplicity: A mapping procedure can be evaluated by separately evaluating its submapping, so the complicated problem can be simplified. (2) Generality: A wide range of application programs and architectures can be easily represented and all mapping algorithms can be easily implemented. (3) Multifunctionality: all the mapping steps, application programs, target ...


A Practical Parallel Algorithm For The Minimization Of KröNecker Reed-Muller Expansions, Paul John Gilliam Jan 1991

A Practical Parallel Algorithm For The Minimization Of KröNecker Reed-Muller Expansions, Paul John Gilliam

Dissertations and Theses

A number of recent developments has increased the desirability of using exclusive OR (XOR) gates in the synthesis of switching functions. This has, in turn, led naturally to an increased interest in algorithms for the minimization of Exclusive-Or Sum of Products (ESOP) forms. Although this is an active area of research, it is not nearly as developed as the traditional Sum of Products forms. Computer programs to find minimum ESOPs are not readily available and those that do exist are impractical to use as investigative tools because they are too slow and/or require too much memory. A practical tool ...


Comparison Of Spice And Network C Simulation Models Using The Cam System, Wen-Tsung Yen Jan 1991

Comparison Of Spice And Network C Simulation Models Using The Cam System, Wen-Tsung Yen

Dissertations and Theses

The performance of SPICE and Network C (NC) circuit simulator when simulating MOS transistor circuits has been investigated and compared. SPICE analog model, NC analog model and NC MOS_PWL model are the three MOS transistor models being used. The comparison between SPICE and NC includes five areas. They are MOS transistor model, circuit analysis and computational methods, limitation on the ability to simulate circuits containing the MOS transistor diode configuration, run time and the ability to build new circuit component models using derived equations.


Freeway Control Via Ramp Metering: Development Of A Basic Building Block For An On-Ramp, Discrete, Stochastic, Mesoscopic, Simulation Model Within A Contextual Systems Approach, Mohamed Yaser Alkadri Jan 1991

Freeway Control Via Ramp Metering: Development Of A Basic Building Block For An On-Ramp, Discrete, Stochastic, Mesoscopic, Simulation Model Within A Contextual Systems Approach, Mohamed Yaser Alkadri

Dissertations and Theses

One of the most effective measures of congestion control on freeways has been ramp metering, where vehicle entry to the freeway is regulated by traffic signals (meters). Meters are run with calibrated influx rates to prevent highway saturation. However, recent observations of some metering sites in San Diego, CA indicate that metering, during peak hour demand, is helping freeway flow while sometimes creating considerable traffic back-ups on local streets, transferring congestion problems from the freeway to intersections. Metering problems stem largely from the difficulty of designing an integrated, dynamic metering scheme that responds not only to changing freeway conditions but ...


Low To Medium Level Image Processing For A Mobile Robot, Cecilia H. Espinosa Jan 1991

Low To Medium Level Image Processing For A Mobile Robot, Cecilia H. Espinosa

Dissertations and Theses

The use of visual perception in autonomous mobile systems was approached with caution by mobile robot developers because of the high computational cost and huge memory requirements of most image processing operations. When used, the image processing is implemented on multiprocessors or complex and expensive systems, thereby requiring the robot to be wired or radio controlled from the computer system base.


An Experimental Investigation Of The Finite Time Efficiency Of A Peltier Refrigeration Device, Thomas Schneider Jan 1991

An Experimental Investigation Of The Finite Time Efficiency Of A Peltier Refrigeration Device, Thomas Schneider

Dissertations and Theses

Since the need of energy conservation has become more and more urgent in the past decades, there has been an increased interest in the study and development of more efficient energy conversion systems. One of the fields that have arisen from that endeavor is a branch of physics called Finite Time Thermodynamics (FIT). It may be said that FIT was initiated through the famous paper by Curzon and Ahlborn (1975) that established new bounds on the efficiency of a finite time Carnot heat engine. Before, the traditional treatments gave a fundamental upper limit on the efficiency of any heat engine ...


Analysis Of A Coordination Framework For Mapping Coarse-Grain Applications To Distributed Systems, Linda Ruth Schaefer Jan 1991

Analysis Of A Coordination Framework For Mapping Coarse-Grain Applications To Distributed Systems, Linda Ruth Schaefer

Dissertations and Theses

A paradigm is presented for the parallelization of coarse-grain engineering and scientific applications. The coordination framework provides structure and an organizational strategy for a parallel solution in a distributed environment. Three categories of primitives which define the coordination framework are presented: structural, transformational. and operational. The prototype of the paradigm presented in this thesis is the first step towards a programming development tool. This tool will allow non-specialist programmers to parallelize existing sequential solutions through the distribution, synchronization and collection of tasks. The distributed control, multidimensional pipeline characteristics of the paradigm provide advantages which include load balancing through the use ...


Development Of An Advisory System For Indoor Radon Mitigation, Patricia Hiromi Byrne Jan 1991

Development Of An Advisory System For Indoor Radon Mitigation, Patricia Hiromi Byrne

Dissertations and Theses

A prototype hybrid knowledge-based advisory system for indoor radon mitigation has been developed to assist Pacific Northwest mitigators in the selection and design of mitigation systems for existing homes. The advisory system employs a heuristic inferencing strategy to determine which mitigation techniques are applicable, and applies procedural methods to perform the fan selection and cost estimation for particular techniques. The rule base has been developed employing knowledge in existing publications on radon mitigation. Additional knowledge has been provided by field experts. The benefits of such an advisory system include uniform record-keeping and consistent computations for the user, and verification of ...


Exploiting And/Or Parallelism In Prolog, Bankim Shah Jan 1991

Exploiting And/Or Parallelism In Prolog, Bankim Shah

Dissertations and Theses

Logic programming languages have generated increasing interest over the last few years. Logic programming languages like Prolog are being explored for different applications. Prolog is inherently parallel. Attempts are being made to utilize this inherent parallelism. There are two kinds of parallelism present in Prolog, OR parallelism and AND parallelism. OR parallelism is relatively easy to exploit while AND parallelism poses interesting issues. One of the main issues is dependencies between literals.

It is very important to use the AND parallelism available in the language structure as not exploiting it would result in a substantial loss of parallelism. Any system ...


Associative Processing Implemented With Content-Addressable Memories, Luis Sergio Kida Jan 1991

Associative Processing Implemented With Content-Addressable Memories, Luis Sergio Kida

Dissertations and Theses

The associative processing model provides an alternative solution to the von Neumann bottleneck. The memory of an associative computer takes some of the responsibility for processing. Only intermediate results are exchanged between memory and processor. This greatly reduces the amount of communication between them. Content-addressable memories are one implementation of memory for this computational model. Associative computers implemented with CAMs have reported performance improvements of three orders of magnitude, which is equivalent to the performance of the same application running in a conventional computer with clock frequencies of the order of GHz. Among the benefits of content-addressable memories to the ...


Computer-Based Parameter Visualization And Decision Making For The Detection And Prediction Of Ovulation : The Ovulo-Computer, Omar Rodolfo Bermudez Jan 1991

Computer-Based Parameter Visualization And Decision Making For The Detection And Prediction Of Ovulation : The Ovulo-Computer, Omar Rodolfo Bermudez

Dissertations and Theses

It is now well accepted by gynecologists that a woman can conceive from an act of intercourse for a maximum of seven days of her menstrual cycle [l]. The reliability of natural family planning methods depends on identifying this window of fertility without ambiguity. Several natural family planning (NFP) methods have been used extensively and with some success. For decades, cycle length and BBT history have been used to forecast the most likely days of ovulation. When greater precision is needed, serum LH assays or ultrasound techniques are used. With the recent development of enzyme-linked immunosorbent assay, various kits have ...


Neural Network Character Recognition With A 2-D Fourier Transform Preprocessor, Daqiao Du Jan 1991

Neural Network Character Recognition With A 2-D Fourier Transform Preprocessor, Daqiao Du

Dissertations and Theses

In pattern recognition applications, it is usually important that the same identification be given for a pattern, independent of a variety of positions, rotations and /or distortions of the pattern within the recognition device's field of view. This research relates to development of a preprocessor for a neural network character recognition system, where the role of the preprocessor is to assist in minimizing the difficulties related to variations of position and rotations of a character within the field of view. The preprocessor explored here was suggested in 1970' (Lendaris & Stanly, 1970), and is implemented here with more recent advances ...


A New Design Approach For Numeric-To-Symbolic Conversion Using Neural Networks, Zibin Tang Jan 1991

A New Design Approach For Numeric-To-Symbolic Conversion Using Neural Networks, Zibin Tang

Dissertations and Theses

A new approach is proposed which uses a combination of a Backprop paradigm neural network along with some perceptron processing elements performing logic operations to construct a numeric-to-symbolic converter. The design approach proposed herein is capable of implementing a decision region defined by a multi-dimensional, non-linear boundary surface. By defining a "two-valued" subspace of the boundary surface, a Backprop paradigm neural network is used to model the boundary surf ace. An input vector is tested by the neural network boundary model (along with perceptron logic gates) to determine whether the incoming vector point is within the decision region or not ...


Evaluating The Role Of Geogrids In The Rehabilitation Of Cracked Dams Via Numerical Techniques, Kelly Dean Uhacz Jan 1991

Evaluating The Role Of Geogrids In The Rehabilitation Of Cracked Dams Via Numerical Techniques, Kelly Dean Uhacz

Dissertations and Theses

Collapse and cracking of debris earth embankment dams is a serious problem in areas of the arid Western United States. The use of geogrids is evaluated in this thesis as a possible solution to prevent or reduce the amount of damage to the structures from collapse and cracking.

An apparatus was designed, constructed, and instrumented to electronically acquire data to evaluate the behavior of geogrids during pullout tests under various normal stresses. The pullout tests were also modelled using numerical techniques to correlate physical test data with numerical test data. Understanding the behavior of the geogrid, in both the physical ...