Digital Commons Network^™

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), …

Photodetachment As A Control Mechanism For Diffuse Discharge Switches, Gerhard Schaefer, P. F. Williams, Karl H. Schoenbach, John T. Moseley

P. F. (Paul Frazer) Williams Publications

Photodetachment is considered as a control mechanism for diffuse discharge switches. Experiments have been performed on photodetachment of ions in the flowing afterglow of a dc glow discharge in oxygen. Experiments with different laser wavelengths and the dependence of the optogalvanic signal on the laser energy flux indicate that 0^- is the dominant negative ion. For an energy flux of 35 mJ/cm², 50 percent of the 0^- ions can be photodetached.

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.

Turbine Blade Image Processing System, Neal S. Page, Wesley E. Snyder, Sarah A. Rajala

Sarah A. Rajala

A vision system has been developed at North Carolina State University to identify the orientation and three dimensional location of steam turbine blades that are stacked in an industrial A-frame cart. The system uses a controlled light source for structured illumination and a single camera to extract the information required by the image processing software to calculate the position and orientation of a turbine blade in real time.

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 …

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. …

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 …

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.

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 …

Gallium Nitride Film Deposition By Ionized Cluster Beam Epitaxy, Ghulum Bakiri

Theses

An experimental Ionized Cluster Beam System similar in design to the one developed at Kyoto University in Japan was. designed and constructed in the Microelectronics Laboratory at NJIT. This involved making the working drawings, having the parts machined and then assembling the system in a vacuum system together with the necessary variable power supplies, meters, controls, gas inlets, cooling water connections, etc.

Eleven deposition runs were then attempted to grow gallium nitride utilizing the system constructed. In a typical deposition run, gallium was vaporized from a boron nitride crucible at 1000° C and allowed to expand through a 0.5 mm …

The Role Of Electrical Noise In Screening Transformers Prone To Failure, Rajeev D. Shirodkar

Theses

Insulation used as a barrier between the high voltage and low voltage windings of a transformer has sites of in- homogeneities like pinholes, cracks or voids, developed during the manufacturing process. Thus, these minute air pockets are stressed much more than the solid dielectric, on the application of a voltage stress, because the dielectric constant of the solid insulation is many times that of the air dielectric. As a result, excitation or ionization takes place in the air (gases). The amount of excited or ionized molecules is proportional to the volume of the inhomogenei- ties within the insulation.

Therefore, experiments …

Interfacial Electrical Properties Of Ion-Beam Sputter Deposited Amorphous Carbon On Silicon, A. Azim Khan, John A. Woollam, Y. Chung, B. Banks

Department of Electrical and Computer Engineering: Faculty Publications

Amorphous, “diamond-like” Carbon films have been deposited on Si substrates, using ion-beam sputtering. The interfacial properties are studied using capacitance and conductance measurements. Data are analyzed using existing theories for interfacial electrical properties. The density of electronic states at the interface, along with corresponding time constants are determined, and the density of interface states is unusually low for an as yet unoptimized

Time-Resolved Two-Dimensional Imaging Of Ground-State Species Using Laser-Induced Fluorescence, R. A. Dougal, P. F. Williams, D. C. Pease

P. F. (Paul Frazer) Williams Publications

Laser-induced fluorescence has been employed to obtain two-dimensional images of the spatial distribution of a vapor in the ground state with nanosecond resolution. The method has a wide range of potential applications, as it can be used to observe any species which has energy levels accessible to tunable laser systems. In the application we describe, aluminum vapor was observed jetting from spark gap electrodes and diffusing throughout the gap volume.

Radio-Frequency-Excited Carbon Dioxide Metal Waveguide Laser, Jonathan Gary Grossman, Lee W. Casperson, O. M. Stafsudd

Electrical and Computer Engineering Faculty Publications and Presentations

A new type of waveguide laser is described in which a single-surface concave metal waveguide also doubles as the grounded electrode in a radio-frequency-excited gaseous discharge. The laser’s output modes and spectrum have been studied theoretically and experimentally for cw CO₂ operation of the laser. Overall operating efficiency and mode stability are comparable with those of conventional dielectric waveguide CO₂ lasers, and advantages of the metal waveguide laser include convection cooling, intracavity mode control, and partial self-alignment.

A Master Clock For The Speed School Impulse Clock System Using Wwv Time Information, John E. Pfeifer Jr.

Electronic Theses and Dissertations

Since approximately February of 1979, the Speed School impulse clock system has not functioned due to a worn-out master clock that was never replaced because of a lack of fund. For this thesis project, a solid-state master clock that performs the same functions as the old mechanical master clock was built for less than $200. The new clock features accuracy traceable to the National Bureau of Standards, automatic reset after a power-down and subsequent power-up, and a daylight savings time provision. A decoder that recovers time information broadcast by radio station WWV from Fort Collins, Colorado was built and interfaced …

Broadband Base Isolated Asymetrically Fed Vhf Antenna, Peter Edward Cunningham

Dissertations

Antennas presently being used for vehicular military VHF communications are narrowband. New generation frequency hopping radios, however, require broadband antennas. The antenna must be base isolated in order to reduce undesirable pattern nulls and impedance variations caused by currents induced on the support structure. Physical constraints limit the antenna length to three meters while operating from a frequency of 30 MHz to 88 MHz.

To satisfy the above requirements a model of a broadband, base isolated, cylindrical antenna less than three meters long was analyzed and built. Equations for the current distribution as a function of the physical parameters were …

Single-Reflection Film—Substrate Half-Wave Retarders With Nearly Stationary Reflection Properties Over A Wide Range Of Incidence Angles, R. M.A. Azzam, M. Emdadur Rahman Khan

Electrical Engineering Faculty Publications

The complex reflection coefficient for the p polarization of a transparent film on an absorbing or transparent substrate can be made equal to the negative of that for the s polarization, and hence the film—substrate system acts as a half-wave retarder (HWR), by proper selection of film refractive index N₁, film thickness d, and angle of incidence Φ. This condition, which generally holds only at normal incidence, becomes possible at oblique incidence also if N₁ is within a certain range, 1 < N₁ < N̂₁ . For a given substrate and given N₁, …

Complex Reflection Coefficients For The Parallel And Perpendicular Polarizations Of A Film-Substrate System, R. M.A. Azzam, M. Emdadur Rahman Khan

Electrical Engineering Faculty Publications

The complex reflection coefficients R_v(ø,ζ) of a film-substrate system for the parallel (v = p) and perpendicular (v = s) polarizations are examined in detail as functions of the angle of incidence ø(0 ≤ ø ≤ 90°) and the reduced normalized film thickness ζ(0 ≤ ζ < 1). For definiteness, the reflection of light of wavelength λ = 0.6328 µm by the air–SiO₂–Si system is assumed. Families of circles that represent the constant-angle-of-incidence contours, their envelopes, and the associated constant-thickness contours ofR_p and R_s are all presented in the complex plane. Furthermore, the amplitude-reflectance and phase-shift functions, |R_v|(ø,ζ) and argR_v(ø,ζ) …

Electrical Engineering, C. J. Thomforde

UND Departmental Histories

This departmental history was written on the occasion of the UND Centennial in 1983.

Line-Adaptive Hybrid Coding Of Images, Tai On Tam, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

This Paper Describes Novel Adaptation Strategy for Hybrid Transform/DPCM Image Coders. This Strategy Has Yielded a 2–8 DB Increase in Signal-To-Noise Ratio in the Transmission of a Head and Shoulders Image at Bit Rates of 1–4 Bits Per Pel and One-Dimensional Transform Block Sizes of 2–16. © 1983 IEEE

The Application Of Bond Graphs To Electrical Machinery And Power Engineering, K. Sirivadhna, Earl F. Richards, Max Darwin Anderson

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Analysis Of The Isolated Induction Generator, L. Ouazenne, George Mcpherson

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Bibliography Of Power Systems Operator Training Resources Ieee Committee Report Prepared By The Pes Working Group On Operator Training (Wg78-4), Max Darwin Anderson

Electrical and Computer Engineering Faculty Research & Creative Works

This paper provides a current listing of training courses, programs, and resource materials for Power System Operator/ Dispatcher training. The training resources are subdivided into five (5) categories: I. Dispatcher training courses and facilities developed by the Suppliers/Manufacturers II. University Short Courses III. Conference Publications IV. Reference Books V. Correspondence Courses A brief description of the offerings of each of the Suppliers/ Manufacturers is included. Copyright © 1983 by The Institute of Electrical and Electronics Engineers, Inc.