Digital Commons Network^™

Microcomputer Controlled Instrumentation System For Studies Of Metabolic Changes In Rats, Murat Dertlioglu

Theses

The system measures the respiratory exchange in rats in a controlled experiment. An interface unit provides data, received from several measurement instruments such as gas analyzers, an electronic flowmeters, electronic thermometer and an electronic hygrometer, to the computer. The data is gathered from different chambers in a multiplexed mode.

The computer samples the chambers sequentially and prints out the results and stores them on the disk. The sampling duration of each chamber and the number of the rats to be tested can be programmed. The system can perform experiments with twelve animals, in the following arrangments, either one group of …

Performance Modeling And Simulation Of Multiple Microcomputer Systems, Moorthy Narayana Hariharan

Theses

Multiple processor systems are the logical choice for applications demanding high computing power, throughput and reliability. Moderately coupled Multiple Microprocessor systems can be applied to a variety of applications demanding high performance. The structure of Multiple Microprocessor systems is examined. Various interconnection structures are analysed for performance comparisons.

Queueing theory is a powerful tool in modeling and analysing Computer systems. Queueing models are developed for popular Multiple processor interconnection topolog es like the Shared memory, Shared bus, Star and Loop configurations.

The usefulness of Digital computer Simulation techniques in estimating the performance of Multiple processor systems is demonstrated through a …

Division-Of-Wave-Front Polarizing Beam Splitter And Half-Shade Device Using Dielectric Thin Film On Dielectric Substrate, R. M.A. Azzam

Electrical Engineering Faculty Publications

No abstract provided.

Fundy Tidal Power Development : Preliminary Evaluation Of Its Environmental Consequences To The Resources Of The State Of Maine, Bigelow Laboratory For Ocean Sciences

Maine Collection

Fundy Tidal Power Development : Preliminary Evaluation of Its Environmental Consequences to the Resources of the State of Maine

A Report to the Maine State Planning Office by the Bigelow Laboratory for Ocean Sciences, April, 1984.

"Technical Report No. 35 - Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine - A Division of Northeastern Research Foundation, Inc."

Contents: Executive Summary / Introduction / Methods / Physical and Biological Consequences / Socio-Economic Consequences / Research Needs / Bibliography / Appendix I. Written Comments on Greenberg Model

Laser-Induced Surface Diffusion, Cheng-Hsiao Wu, Jonathan I. Gittleman

Electrical and Computer Engineering Faculty Research & Creative Works

A Brownian motion model for laser-induced surface diffusion is proposed to account for the kinetics of surface transport of the evaporated molecules from a thin discontinuous film under a focused laser beam. The model is solved exactly where the evaporation rate of the molecules is assumed to be proportional to the temperature rise above the ambient of the absorber layer. The surface diffusion constant and molecular velocity are obtained by comparing the results of calculations with transmission electron micrographs of recorded pits in Te trilayer opticial discs. These values are in good agreement with Einstein's relation.

Block Transform Coding Of Presample Filtered Data, Thomas A. Shull

Electrical & Computer Engineering Theses & Dissertations

This dissertation addresses the application of non-adaptive transform coding for bit rate reduction of presampled filtered data. Transform coding is examined as an alternative to conventional pulse code modulation (PCM) for multi-source, fixed rate data acquisition systems. Typical bandlimiting presample filters introduce redundancy into the sequence of data samples. Linear transformation of successive N-length blocks of the data sequence and subsequent binary coding of the resulting components is shown to lead to reduced average bit rate for the same less distortion as PCM.

Four Butterworth filters, two corresponding to eight bit PCM systems, and two corresponding to ten bit PCM …

The Development Of A Microprocessor Controlled Linearly Actuated Valve Assembly, Raymond H. Wall

Mechanical & Aerospace Engineering Theses & Dissertations

The development of a proportional fluid control valve/assembly is presented. This electro-mechanical system is needed for space applications to replace the current proportional flow controllers that use bulky hydraulic or pneumatic actuation systems. The flow is controlled by a microprocessor system that monitors the control parameters of upstream pressure and requested volumetric flow rate. The microprocessor achieves the ·proper valve stem displacement by means of a digital linear actuator. A linear displacement sensor is used to measure the valve stem position. 'Ibis displacement is monitored by the microprocessor system as a feedback signal to close the control loop. With an …

A Plasma Focus Interrupting Switch, Gregory Francis Knapp

Electrical & Computer Engineering Theses & Dissertations

The feasibility of using a dense plasma focus (DPF) as a current interrupting device has been investigated. Specifically, a 34-kJ, Mather-type DPF was modified to accept a third electrode so that a discharge could be created between this electrode and the center electrode of the DPF by a 10-kJ inductive energy storage circuit. It was anticipated that the accelerating mechanisms of the DPF pinch, which are known to cause a rapid reduction in the DPF current, would interrupt the 1-kA to 10-kA secondary discharge current thus forcing the secondary current through an external load and hence result in power amplification. …

Proposal For A Digital Pseudorandom Number Generator, C. Downey

Articles

A digital hardware implementation of a linear congruential sequence generator using shift and add techniques of multiplication is described. The sequence is of long period, low serial correlation and is rectangularly distributed. The method has certain advantages over conventional feedback shift register techniques.

Awqpsk : An Optimum Modulation Technique For Spread Spectrum Communication, Madjid A. Belkerdid

Retrospective Theses and Dissertations

Quadrature phase shift keying (QPSK) and minimum shift keying (MSK) are the two most used M-ary modulation techniques in Direct-Sequence (DS) Spread Spectrum Communication systems. This thesis introduces a new modulation technique that can compete well with QPSK and MSK in many applications. This new modulation technique, made up of a superposition of one QPSK signal and two amplitude weighted QPSK signals, is called Amplitude Weighted Quadrature Phase Shift Keying (AWQPSK). It is found to have the same probability of error as QPSK and MSK techniques. It has a higher bandwidth efficiency in bits/sec/Hz than QPSK and MSK. It has …

Correction To “Two-Dimensional Markov Representations Of Sampled Images”, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Radiation Damage To Gaas Solar Cells Including Isotropic Effects, Larry Victor Stock

Physics Theses & Dissertations

A model is developed for the short circuit current of a GaAs solar cell due to radiation (proton or electron) induced defects in the crystal structure. This model is verified by a comparison with proton and electron irradiation results. For electron radiation and energetic protons (energy> 10 MeV), it is found that the damage in the crystal is independent of the angle of incidence. On the other hand, for lower energy proton radiation, the damage as a function of cell thickness is highly dependent on incident angle and energy. The cell's response to low energy protons is strongly dependent on …

Propagation Of Airy-Hermite-Gaussian Waveguide Modes In Free Space, Lee W. Casperson, O. M. Stafsudd, Leroy V. Sutter, Jonathan Gary Grossman

Electrical and Computer Engineering Faculty Publications and Presentations

The cavity modes of metal strip waveguide lasers are most simply expressed in terms of Airy-Hermite-Gaussian functions. The free space propagation of the resulting beam modes has been examined, and both near- and far-field patterns have been calculated and measured. Phase plates may be useful for enhancing the far-field intensity.

Decentralized Optimal Control With Application To Dynamic Routing In Computer Communication Networks, Ning Wang

Dissertations

This research considers the dynamic routing problem of computer communication networks in the framework of decentralized control theory. The routing dynamics are modeled in terms of a state equation with multiple controllers. Routing, or control of message flow, is formulated as an optimal control problem with multiple decision makers. Each decision maker may have access to different set of information and work cooperatively to optimize a common system performance index.

Necessary and sufficient conditions for optimality are derived for a system with a deterministic and a stochastic traffic patterns under a linear information structure and a quadratic performance index. The …

Lateral Coherence Of Aerosol-Scattered Laser Radiation, Donald D. Duncan, D. E. Larch

Electrical and Computer Engineering Faculty Publications and Presentations

To assess the probability of detection (by interferometric techniques) of illumination by a coherent source, we characterize the lateral coherence of the off-axis aerosol scattered radiation by applying the van Cittert-Zernike theorem. We find that, for 1.061-pm radiation at a target range of 1 km, the scattered radiation beyond 3.5 cm off axis does not display appreciable lateral coherence.

Pseudo-Brewster And Second-Brewster Angles Of An Absorbing Substrate Coated By A Transparent Thin Film, R. M.A. Azzam, T F. Thonn

Electrical Engineering Faculty Publications

The pseudo-Brewster angle of minimum reflectance for the p polarization, the corresponding angle for thes polarization, and the second-Brewster angle of minimum ratio of the p and s reflectances are all determined as functions of the thickness of a transparent film coating an absorbing substrate by numerical solution of the exact equations that govern such angles of the form Re(Z′/Z) = 0, where Z = R_p, R_s, or ρ represent the complex amplitude-reflection coefficients for the p and s polarizations and their ratio (ρ =R_p/R_s), …

Limiting Efficiencies For Multiple Energy-Gap Quantum Devices, Cheng-Hsiao Wu, Richard M. Williams

Electrical and Computer Engineering Faculty Research & Creative Works

We have used a thermodynamic model to calculate theoretical limiting efficiencies for simple and multiple gap solar cells. The limiting efficiency is 26% for a simple solar cell of hydrogenated amorphous silicon, operating at one Sun sensitivity. For a multiple gap cell made from hydrogenated amorphous silicon, together with a second cell, made from a material with lower band gap, it is 38%. The optimum band gap for the second material is 1.0 eV.

Spectral Analysis Of Brainstem Auditory Evoked Responses, Amir Hossein Massumkhani

Theses

In this study, the power spectrum density of the brainstem auditory evoked responses is estimated by the method of periodogram. Several techniques for reducing the leakage due to the finite length of data, smoothing the spectrum and reducing the ambiguity in the spectrum due to the resolution are studied. It is shown that a Hamming window reduces the leakage considerably and zero extention of the data to 512 points produces sufficient spectrum bandwidth. Three major peaks are observed at 100, 500, and 1000 Hz which are stable for different evoked responses. In one case with a delayed wave V, the …

Design Of Efficient Algorithms Through Minimization Of Data Transfers, Yong Mo Chong

Electrical & Computer Engineering Theses & Dissertations

This thesis explores the time optimal implementation of computational graphs on a finite register machine. The implementation fully exploits the machine architecture, especially, the number of registers. The derived algorithms allow one to obtain time efficient implementations of a given graph in machines with a known number of registers.

These optimization procedures are applied to digital signal processing graphs. It is shown that the regular structure of these graphs allows one to identify computational kernels which, when used repeatedly, can cover the entire graph. The l- and r-register implementations of Hadamard and Fast Fourier Transforms using various computational kernels are …

Circuit Analysis Of A Gas Flow Switch, Teri Marie Owens

Electrical & Computer Engineering Theses & Dissertations

The circuit analysis of a gas flow switch is presented. The objective of the analysis is to model the switching process during spark gap breakdown. This information is useful in understanding switch operation and identifying ways to improve switch performance.

A lumped circuit model is used to describe a gas flow switch during the switching process. Certain circuit element values are determined experimentally through static tests. Other component values, including a time-varying switch resistance and inductance, are estimated from current measurements. In particular, unknown constants in expressions for gap resistance and inductance are determined using an iterative parameter estimation technique. …

Data Acquisition And Parameter Identification In Electro-Oculography, Wolfgang Poelzleitner

Theses

Electro-Oculography (EOG) is used in clinical ophthalmology to measure the time response of the corneoretinal potential (CRP) to changes in light intensity. An automatized data acquisition and system modeling link has been developed that significantly reduces processing time presently required for EOG. The data acquisition is performed on a microprocessor based instrument, which supervises the EOG-test, measures the potential and, after completion of the test, transfers the results to a mainframe computer. Parameter identification routines provide graphical representation and mathematical models for the CRP. Both nonlinear curve fitting methods and Least Squares System Identification schemes are used.

Self‐Refraction Of Nonlinear Capillary‐Gravity Waves, Partha P. Banerjee, Adrianus Korpel, Karl E. Lonngren

Electrical and Computer Engineering Faculty Publications

Self‐refraction effects have been observed during the propagation of deep‐water capillary‐gravity waves. The observations are shown to be in qualitative agreement with the theory of self‐focusing and defocusing in a cubically nonlinear medium in the presence of diffraction.

Explicit Equations For The Second Brewster Angle Of An Interface Between A Transparent And An Absorbing Medium, R. M.A. Azzam

Electrical Engineering Faculty Publications

The second Brewster angle _ΦB2, at which the ratio R_p/R_s of intensity reflectances R_p and R_s for the parallel (p) and the perpendicular (s) polarizations of a dielectric-conductor interface reaches a minimum, is determined by Im[(u - ∊)(u - ∊)²/(u - 2∊)²] = 0, where ∊ is the complex ratio of dielectric constants of the media of refraction and incidence, ∊ = ∊/(∊ + 1), and u= sin²_ΦB2. An equivalent quartic equation in u …

Simple And Direct Determination Of Complex Refractive Index And Thickness Of Unsupported Or Embedded Thin Films By Combined Reflection And Transmission Ellipsometry At 45° Angle Of Incidence, R. M.A. Azzam

Electrical Engineering Faculty Publications

Measurements of the polarization states (represented by complex numbers X_r and X_t, respectively) of light reflected and transmitted by an unsupported or embedded thin film, for totally polarized light (with nonzero p and s components) incident at 45°, permit simple, direct, and explicit determination of the film's complex refractive index N₁ independently of film thickness or input polarization. If α = X_r/X_t, we find that α = r_s + r_s^-1, where r_s is Fresnel’s complex reflection coefficient of the ambient-film interface for the s polarization at …

Maximum Minimum Reflectance Of Parallel-Polarized Light At Interfaces Between Transparent And Absorbing Media, R. M.A. Azzam

Electrical Engineering Faculty Publications

The pseudo-Brewster angle Ø_pB, of minimum reflectance R_pm for the parallel (p) polarization, of an interface between a transparent and an absorbing medium is determined by Im{(∊ - u)[1 - (1 + ∊^-1)u]²} = 0, where ∊ is the complex ratio of dielectric constants of the media and u = sin²ø_pB. It is shown that, for a given value of the normal-incidence amplitude reflectance |r|, there is an associated normal-incidence phase shift, δ = δ_mm, that leads to maximum minimum parallel reflectance, …

Experiments Conducted On The Electron Beam Produced By A Dense Plasma Focus, Mark Steven Pronko

Electrical & Computer Engineering Theses & Dissertations

An experimental investigation was conducted using a 34-kJ Dense Plasma Focus (DPF) in which the possible enhancement of the electron beam was addressed. Electron beams ejected from the DPF have been observed to exceed 30 kA with pulse durations of a few nanoseconds. Enhancement was considered to be either an increase in the probability that the peak beam current exceeded some lower limit, or an increase in the mean energy of the beam electrons. The investigation was divided into two parts, each addressing one of the aspects of enhancement.

In the first part of the investigation, an axial magnetic field …

Optimization Of A New Linear Fm Detector Using Digital Signal Processing Techniques, Edward J.A. Kratt

Dissertations

This dissertation describes and synthesizes a new member of the family of FM detectors introduced earlier by Klapper and Kratt. A salient property of these detectors is low delay with excellent sensitivity. The emphasis in the new detector is on the ease of digital implementation. In addition, the new detector is also extremely linear. In congruence with the other Klapper-Kratt detectors, it makes use of zero group delay elements, balance at RF, quasi-synchronous detection and carrier cancellation. The Performance of the detector is mathematically analyzed under the conditions of a modulated input wave, sinewave [sic] interference, and noise. The results …

Application Of Fuzzy Theory To Pattern Recognition, David Usechak

Dissertations

Piecewise curve approximation is used to describe boundaries of objects in pictures and waveforms. The method consists of linear and quadratic piecewise polynomial approximations in which the error must not exceed a predetermined cost threshold. A fuzzy Bayes model is used to determine if a breakpoint exists within an interval I_n or between intervals I_n and I_n+1 and to determine whether these intervals can be merged for data compaction reasons. In order to achieve these objectives a new fast algorithm has been proposed which gives good curve/object fitting. This algorithm uses a technique for generating generalized inverse …

An Experimental System For Observation Of The Rat Coronary Microcirculation Using Digital Image Processing, Wolfgang Braun

Theses

A system was constructed which allows direct observation of the coronary microcirculation of the beating rat heart. An EKG triggered strobe is used on the microscope light source to "stop" the action of the beating heart so the surface microvessels can be observed di rectly under the microscope. Experimental results are recorded on videotape and played back for frame-by-frame analysis of the data using digital Image processing techniques such as digital filtering, image extraction, image enhancement and edge detection.

The application of image enhancement techniques (high order and low order enhancement methods ) as well as edge detection using a …

Automated Instrumentation System For Studies Of Metabolic Rates In Rats, Suhas P. Pathak

Theses

The task of the instrumentation system is to measure the respiratory exchange in rats in a controlled experiment. Air is drawn at a predeter-mined rate in and out of rat chambers. The proportion of oxygen and carbon dioxide in the ensuing air indicates the respiratory rate of the rat. The entire operation is controlled by a microcomputer whose most important functions are: to direct the flow of air through the rat chambers by switching valves; and to collect data about the percentages of gases in question.

Thus with the help of a computer it is possible to monitor and control …