Engineering Commons^™

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 …

Error Detection For Data Communication Systems, John Biancamano

Theses

A description of the problems encountered in the data communications field and the various solutions can be found in a number of diverse, and often theoretical sources. My intention in writing this thesis is to bring together, in a practical and understandable manner, the theory and the application of a method of error detection used extensively in data communication systems known as the Cyclic Redundancy Check (CRC).

To provide some background on the subject, a description of a data communication system is presented, and the possible sources of error are explored in some detail. Data transmission formats are described, and …

Remote Attitude Measurement Techniques, Frank John Elmer

Dissertations

A method has been developed for solving practical problems which can be expressed in terms of physical geometry. These problems often involve combining directional information observed by remotely located sensors reported in their own respective local coordinate systems. To transform this information into a common coordinate system, the attitude of the sensors must be measured with respect to this common coordinate system.

Physical geometry is a generalization of mathematical -geometry where objects define the endpoints of figures composed of ensembles of lines. A probabilistic approach has been taken which is based on the fundamental assumption that the objects can be …

Pattern Generation And Fault Detection In Digital Circuits Using A Microprocessor, Syed Riffat Ali

Theses

The main object of this Professional Project was to establish a microcomputer based system which could detect faults in digital circuits. Hardware and software for the Motorola 6800 microcomputer system was fully developed. Node level diagnostic programs were then used to pump known "Bit Patterns" into digital circuits and responses recorded via Pseudorandom binary sequence generator using CRC code. This method also known as "Signature Analysis" was then applied to detect faults successfully in Universal Asynchronous Receiver Transmitter or UART Circuits.

Analysis Of Oscillations In Nonlinear Systems Using Multiple Input Describing Functions, Frederic Lee Swern

Dissertations

Sufficient conditions for oscillation as well as absence of oscillations are presented for a class of systems containing one lumped linear element and a differentiable nonlinearity. The results are obtained by estimating the error inherent in using a describing function analysis. Contraction type arguments are used to show common topological properties of the describing function solution and the balance of first harmonic terms of the system.

After discussing the describing function method, two theorems are presented regarding existence or nonexistence of oscillations from homotopic considerations. A graphical method for examining systems with power law nonlinearities is given using a parameter …

Investigations Of Gate Turn-Off Structures, Hans Werner Becke

Dissertations

Research and Development was done on gate turn-off devices. The aim was i) to improve turn-off capability without compromise of turn-on, on-state, and useful temperature range, ii) to implement "safe" turn-off.

A) The dependence of the electrical device characteristics on cathode width for an optimized vertical structure was determined. Fall times of 100 to 200 nsec and risetimes of <400 nsec were simultaneously obtained for average current densities of 53 A/cm² @ T_j = 125°C. From spreading resistance analysis the fast t_r and t_f response is shown to be a consequence of proper Au-distribution in the active device volume.

From transient analysis it is concluded that for safe …

Statistical Averaging In Position Determination By Holography Under Turbulence Conditions, Paul Aloysius Mcgovern

Dissertations

An investigation of several, disparate phenomena is conducted with the aim of developing a novel surveying system capable of overcoming the limitations imposed by turbulence in modern surveying. This method incorporates standard holographic techniques and time domain statistical averaging of survey data.

Some pertinent characteristics of atmospheric turbulence are reviewed, and the restrictions imposed on standard surveying practices by such turbulence are identified. A model for the turbulent medium is proposed on the basis of previous work and several theoretical results are summarized and extended.

On this basis the technical characteristics of the proposed technique are developed and each step …

The Minimum Maximal-Cube Covering Approach To Switching Theory, Yu-Tsang Gene Hwang

Dissertations

This dissertation is devoted to the construction of a new algebraic structure for the K-map so that algorithms and theorems can be derived for the minimization of Boolean functions and at the same time provide for the manipulation of Boolean functions as freely as one could on the K-map.

Computer programs have been included to demonstrate the theory and numerous examples of various complexity have been worked out in the appendices.

A Microprocessor Based Digital Logic Simulator, Kevin Dresher

Theses

It is the intent of this thesis to acquaint the reader with a tool which is available for use in the digital circuit design field. The reader is now able to totally simulate via DLS the digital logic design he creates on paper before it ever takes a hardware form. The computer program accepts a detailed description of the schematic and creates timing diagrams, loading statistics, cross references, and various lists for future documentation.

The user needs no programming knowledge and will find the requirements to run a simulation with DLS extremely user oriented. The simulation descriptions and command language …

Theory And Design Of Cyclotron-Wave Traveling-Wave Amplifiers, Arthur H. Gottfried

Dissertations

A theory and design procedure for traveling-wave tubes using cyclotron-wave interactions is developed. An analysis is presented of the energy exchange mechanism and the axial beam velocity spread induced by the r.f. interactions. The analysis of the energy spread in a realistic model of the beam with nonzero size and nonzero space-charge density shows that higher maximum efficiencies at higher power is attainable (with collector depression) in cyclotron-wave amplifiers than in synchronous-wave amplifiers.

A one-watt, and a ten-watt cyclotron-wave amplifier at 3 GHz, utilizing bifilar helix circuits, scaled from a 2 kW, 5 GHz design, were constructed. A computer was …

Noise Performance Of The Klapper-Kratt Low Delay Fm Detector, Allan Brown Tarbell

Dissertations

In this dissertation the dual differentiator version of the Klapper-Kratt FM detector family is investigated with additive Gaussian noise. Prior analysis of this new detector family has been limited to the noiseless case.

The investigation was conducted both analytically and experimentally. First, the dual differentiator version of the Klapper-Kratt detector was mathematically analyzed, assuming an unmodulated carrier plus additive Gaussian noise. This analysis was verified by assembling the detector and measuring its performance in the laboratory.

It was discovered that the Klapper-Kratt detector without limiter performs identically to the conventional limiter discriminator in the linear improvement region. When compared to …

Signal Processing Techniques For Analysis Of Heart Sounds And Electrocardiograms, Alan D. Bernstein

Dissertations

Audible heart sounds represent less than 5% of the vibrational energy associated with the cardiac cycle. In this study, experiments have been conducted to explore the feasibility of examining cardiac vibration by means of a single display encompassing the entire bandwidth of the oscillations and relating components at different frequencies. Zero-phase-shift digital filtering is shown to be required in producing such displays, which extend from a recognizable phonocardiogram at one frequency extreme to a recognizable apexcardiogram at the other. Certain features in mid-systole and early diastole, observed by means of this technique, appear not to have been previously described.

Frequency …

Synthesis Of Multiarea Grid Power Systems, Bharat C. Patel

Dissertations

This dissertation presents improved development in the formation of a generalized transmission loss (B)-matrix for a multiarea grid power system. In the procedure, the individual tie powers of each area are replaced by the net interchange, sneak and circulating powers. The latter two variables are directly eliminated in the power reference frame using actual impedances, unlike current methods that require the elimination of sneak and circulating currents, the formation of complex tie current model and the complex tie power model. Consequently, manipulation of large complex current, power and impedance matrices is avoided reducing both computer time and memory requirement. Further, …

A New Mathematical Model For Nephron Macromolecular Selectivity, John Anthony Domiter

Theses

A mathematical model describing the displayed selectivity of the kidney nephron to macromolecules of varying particle size is presented. Diffusion and electrical forces are considered to be the sole mechanisms of transfer. The mass transfer principles responsible for selectivity are considered to occur within the capillary structure, and not within the membrane wall. A charge is assumed to be characteristic of the macromolecule and the membrane wall. Models describing both charged and uncharged solutes are developed.

A non-linear least squares technique, developed by Marquardt, is used to curve fit the derived functions to data relating fractional clearances of dextran and …

Reliability And Surface Degradation Aspects Of Synthetic Insulator Materials For Hv Application, Satyapal S. Bhatia

Dissertations

This study is a theoretical and experimental investigation on the state of the art of synthetic insulators for outdoor high voltage transmission systems.

The surface of a polymeric material is known to be degraded by, among other things, environmental stresses such as UV, air pollutants, etc. The reliability of an insulator material is governed by the surface and other characteristics that do not drift much as a function of stresses and time.

The surface characteristics of various synthetic materials, when these materials were exposed to UV radiation in the laboratory were studied. The changes in the surface properties of these …

Reliability Of Mos Devices : Threshold Voltage Instability, Sesha Rajamani Shankar

Dissertations

A very important factor in the reliability of MOS devices is the stability of the threshold voltage. This dissertation examines the effects of positive and negative gate bias stresses at elevated temperatures on the drift in the threshold voltage of MOS field effect transistors.

Over 400 p-channel enhancement mode devices were life tested under different temperature and gate bias conditions for periods of up to 15,000 hours, and the drift in their threshold voltages studied and analyzed. It was found that under both negative and positive bias-temperature tests, the threshold voltage drifted towards more negative values, though in the negative …

Acoustical Holography By Holographic Interferometry, Amin Mohamed Hanafy

Dissertations

The ability to "see" with sound has long been an intriguing concept. It is apparent that ultrasonic energy can give an image of an object not obtainable with light or even with x-rays.

In this dissertation, a novel "three-step acoustical holographic imaging system" is described and several means for its implementation are analyzed. A novel holographic acoustic image converter, which constitutes a fundamental link in the three step imaging method was also developed. The use of optical holographic techniques to convert an arbitrary acoustic image to a visible image is conducted and resulted in the introduction of the new technique …

Sparsity And Decoupling In Load Power Flow Analysis, Kenneth Nazimek

Theses

This paper presents some recent ideas on and methods created by power engineers for the solution of the Load Flow Problem. Beginning with an analysis of the solution of large systems of linear equations, techniques employing elementary matrix operations are discussed to reduce the amount of calculations necessary to achieve repeated solutions. Recent interest in taking advantage of the characteristic sparsity of the admittance matrix is also examined. The problems of operating on and computer storage of large sparse matrices are investigated. Methods to efficiently order, store and work with large sparse matrices are discussed and demonstrated. The general acceptance …

Dynamics Of The Glucose-Insulin-Glucagon System, Joseph P. Hartmann

Theses

A computer model for the Dynamics of the Glucose-Insulin-Glucagon System has been developed for a 17.5 kg canine using the Continuous Systems Modeling Program (CSMP) for the 360 Computer System. The major body components controlling the glucose dynamics (liver, pancreas, body muscle, blood flow, and body fluid compartments) have been modeled in terms of either their production, absorption, or transport of glucose, and the concentration levels of both the hormones and substrates perfusing the body component. A set of mneumonics has also been developed to label the hundreds of constant and variable terms required to describe a complex system of …

Application Of Multilevel Control Techniques To Classes Of Distributed Parameter Plants, Frederick Donald Chichester

Dissertations

This study concerns the application of a combination of multilevel hierarchical systems analysis techniques and Pontryagin's minimum principle (multilevel control) to the problem of controlling optimally two classes of dynamic distributed parameter plants representing concentrations balances in streams, rivers and estuaries. The concentrations treated in this study are those deemed the most effective indicators of water quality, dissolved oxygen (DO) and biochemical oxygen demand (BOD).

One class of plants treated in this study consists of linear continuous distributed parameter plants represented mathematically by sets of simultaneous partial differential equations. Optimal control of a plant of this class is initiated by …

The Effects Of Optical Path Perturbations During Recording On A Reconstructed Holographic Image, Stevan Israel Feldman

Dissertations

The effects of optical path perturbations occurring during recording on the reconstructed image of a hologram are investigated. It is shown that such variations of optical path are equivalent to conditions of holographic interferometry which can be classified in three categories: 1) object motion alone, 2) film motion alone, and 3) simultaneous film and object motion; all motions are defined with respect to the stationary reference source during the recording of the hologram.

The theory concerning the effects of object motion alone on the radiance distribution of a reconstructed holographic image has already been developed by previous researchers and is …

Investigation And Optimum Design Of The Generalized Second-Order Phase-Locked Loop, William Allen Novick

Dissertations

In this dissertation, a second-order phase-locked loop (PLL) in which the loop filter contains complex zeros is investigated in both its linear and nonlinear modes of operation; prior designs used a filter containing a simple zero on the negative real axis. This "generalized" second-order PLL had been heretofore essentially unexplored.

The basic characteristics of the generalized second-order PLL operating in the linear mode including the open and closed-loop responses and the corresponding root locus were generated and compared against those of the conventional second-order PLL. As in the conventional case, the generalized second-order PLL is found to be unconditionally stable. …

An Investigation Of The Optical Absorption Properties Of Silicon As Related To Its Electrical Conductivity, Onofrio Louis Russo

Dissertations

The purpose of this study is to demonstrate the feasibility of obtaining the electrical conductivity of band gap semiconductors, by considering the absorption of radiation in the visible region. The experimental evidence confirmed predictions that the conductivities of the silicon samples are related to the horizontal displacement of energy in the absorption curves. The material used in this study was p-doped silicon, although the approach should be valid in general for either elemental or compound semiconductors.

The absorption coefficient for silicon was measured in the radiation region between 2.0 and 3.0 ev. This region above the indirect band gap (= …

Optimal Control And Identification Of Stochastic Systems Using Differential Game Theory, Harry Marvin Burbank

Dissertations

This dissertation deals with linear systems subjected to stochastic disturbances. The class of stochastic processes considered is the class of second order stochastic processes characterized by having finite continuous covariance. The properties of the covariance provide means to formulate optimization problems without the difficulties present when the covariance is not finite or continuous.

The first aspect studied was several classes of optimal control problems. The effects of the stochastic processes were approximated by the effects of its first two moments. This procedure resulted in allowing optimal system controls to be found whatever the first two moments of the stochastic input …

Design Of A Yig-Tuned Oscillator, Tien Liang Jin

Theses

A technique for designing YIG (yttrium-iron garnet) tuned transistor oscillators, tunable over the range of frequencies from 500 to 950 MHZ, is presented. The approach taken differs appreciably from that used in the design of conventional LC-tuned oscillators. One major difference is that the YIG tuning mechanism is electrically controlled. The YIG tuning element is treated as a single unit and is not resolved into an equivalent LC circuit. Instead, a direct method using reflection coefficients measured at network terminals to characterize various design stages is applied. The transistor is also characterized by reflection and transmission coefficients, i.e., S-parameters. Thus …

The Theory Of Multiple Measurements Techniques In Distributed Parameter Systems, Babajimi Claudius Okunseinde

Dissertations

A comprehensive theory of multiple measurements for the optimum on-line state estimation and parameter identification in a class of noisy, dynamic distributed systems, is developed in this study. Often in practical monitoring and control problems, accurate measurements of a critical variable are not available in a desired form or at a desired sampling rate. Rather, noisy independent measurements of related forms of the variable may be available at different sampling rates. Multiple measurements theory thus involves the optimum weighting and combination of different types of available measurements. One of the contributions of this work is the development of a unique …

Synthetically-Generated Holographic Memory System Utilizing Partially Coherent Light, William A. Barrett

Dissertations

This dissertation proposes a novel form of optical ROM for the digital computer. This memory makes use of holographic techniques because of the advantages offered by holographic memories over conventional optical ones, especially with regard to dust and scratch sensitivity.

These advantages have long been recognized by workers in the field, indeed several holographic optical memories have already been proposed.

A survey of the state of the art of digital computer memories is offered in the introductory part of the thesis. Particular emphasis is placed on optical memories. A brief review of basic holographic theory is also included for reference. …

Steady State And Dynamic Performance Of Anisotropic Reluctance Motor, S. Chandrasekhara Rao

Theses

The paper deals with a special type of reluctance motor called Anisotropic rotor reluctance motor. As the name implies, advantage is taken of the internal anisotropy of the rotor magnetic structure. Axially laminated grain oriented silicon steel is used in the rotor. This unconventional configuration of assembly of rotor laminations results in a high ratio of direct axis to quadrature axis reluctance. Compared to the conventional reluctance motor, pull out torque of more than three times and a power factor as high as in an induction motor is obtained. Several motors of ratings up to 60 HP. were built and …

Dynamics Of Interconnected Systems With Pulse Frequency Modulators, Halil Ozcan Gulcur

Dissertations

The objective of this dissertation is to study the dynamics of systems consisting of interconnections of an arbitrary number of complete-reset pulse frequency modulators (CRPFM's) and linear dynamical subsystems (in general, time-varying, lumped and/or distributed). CRPFM, which represents a generalization of several types of pulse frequency modulators (PFM's), consists of two basic components; a multi-input dynamic element, called the timing-filter (TF) and a threshold device (TD). Whenever the output of the TF reaches a given threshold value the TD generates an impulse and, at the same time, resets all the states of the TF to zero. This dissertation is devoted …

Correlation Of Drain Breakdown With Excess Noise And Other Surface-Related Phenomena In Enhancement Mosfets, Jerry J. Rij

Theses

An investigation of semiconductor surface-related phenomena has been undertaken to correlate 1/F noise with drain breakdown in P-channel enhancement MOSFET's. Increases in the intensity of drain current fluctuations at 10Hz and at 1KHz, particularly at the higher frequency, was observed following accelerated life-testing for threshold voltage drift. It was also concluded that mobile ions near the oxide-semiconductor interface produce a sharp increase in fast trapping centers. It was also found that 1/F noise intensity consistently peaked at the threshold of drain breakdown and that it steadily decreased with further increases in drain current. Of all the transistors tested, those with …