Electrical and Computer Engineering Commons^™

An Analysis Of Transmitted Signal Distortion Resulting From Antenna To Reflecting Surface Velocity., J. Philip Castillo

Electrical and Computer Engineering ETDs

This paper presents a stud of the distortion of a transmitted signal due to Doppler frequency spreading and amplitude modulation as a consequence of the relative velocity between the transmitter and a reflecting surface.

The Doppler effect is a well-known phenomenon associated with the apparent compression, or length of the transmitted signal wave-length, resulting from a positive or negative relative velocity between a transmitter and receiver. In this thesis one of the problems will be the determination of the degree of frequency spreading due to a finite antenna beam width as the transmitter approaches a reflecting surface at a constant …

Production And Spectral Determination Of Low-Energy, Flash X Rays, Robert I. Loebman

Electrical and Computer Engineering ETDs

With the rapidly expanding use of X-radiation devices for medical, industrial and military purposes, the need arises for diverse methods of producing and measuring the X-ray portion of the electromagnetic spectrum.

X rays may be purposefully produced by a source in a continuous manner, in short pulses or flashes or in a random manner. X rays are also produced undesirably by devices having extremely high voltages or as a byproduct of some energy-producing device such as a nuclear weapon. In most cases X radiation is produced over a wide spectral range of varying intensities rather than at discrete energy levels …

Electronic Technique For Resolving Ambiguities Of Sinusoidal Function Transducers., James W. Campbell

Electrical and Computer Engineering ETDs

A circular function transducer is a device whose output is a circular trigonometric (sinusoidal) function of the input to the device. The sinusoidal nature of this class of transducer's output results in identical responses for many admissible inputs. Consequently, an ambiguity exists as to which of the many possible input values produce any particular output value. Even a history of the output from an initial reference input becomes ambiguous once the output completes one cycle of the sinusoid. To be a generally useful instrumentation component, the ambiguity of circular function transducers must be resolved.

Circular function transducers are currently used …

The Effect Of Nuclear Radiation On Oxidized Silicon Surfaces., Jerry A. Hood

Electrical and Computer Engineering ETDs

The change in properties of oxidized silicon surfaces with nuclear radiation is most apparent in devices controlled from the surface. The two devices of most specific interest are the insulated gate field-effect transistor and the metal-silicon dioxide-silicon capacitor. This chapter reviews the basic operating theory of these devices excluding the radiation induced defects. Many other devices such as the fieldister and surface-controlled avalanche devices would be equally or more sensitive than the two devices chosen for study. The devices chosen, however, are those of most immediate interest for use in a nuclear radiation environment .

An Analysis Of The Impedance Of Two Types Of Electric Antennas Designed For Undersea Applications., Vincent R. Chavez

Electrical and Computer Engineering ETDs

The problem of radio wave propagation using antennas submerged in sea water has received much attention in recent years. As early as 1940 Norgorden [1] prepared a paper on the problem of propagation of radio waves from a transmitting antenna in air to a receiving loop antenna in sea water. Further work on the loop antenna was performed in 1946 by Quinn and Norgorden [2]. An analysis of a Hertzian dipole in an infinite, conducting medium was done by Tai [3] in 1947. He showed that a meaningful expression for the radiation resistance of the Hertzian dipole in a conducting …

An Analysis Of The Signal Processing In A Radio Altimeter Utilizing Random Angle Modulation, Donald F. Post

Electrical and Computer Engineering ETDs

Excerpt from the introduction:

This paper presents an analysis of the signal processing in a continuous wave, fixed-range, radio altimeter which utilizes random angle modulation, i.e., the modulating function is a sample function from a random process. The mathematical model of the altimeter is shown in block diagram form in Figure 1, and the physical situation in which the altimeter operates is illustrated in Figure 2. As shown in Figure 2, the altimeter is assumed to be on the vehicle "V" which has a relative velocity v with respect to the reflecting plane P. The velocity vector might have any …

A Study Of Learning In Adaptive Systems., In Ku Kang

Electrical and Computer Engineering ETDs

The purpose of this study is to investigate the structures of learning processes and their applications to adaptive systems. The learning processes in this study are based on Bayes learning model, which well describes the nature of learning and also is a natural choice from the viewpoint of statistical decision theory.

On The Application Of Bayesian Learning In Discrete Communication Systems., Chien Fong Chao

Electrical and Computer Engineering ETDs

It is the requirement of many communication systems that the transmission of information should not only be reliable, but also efficient with respect to the capacity of the communi­cation channel used.

Transient Radiation Effect On Semiconductor Controlled Rectifiers, Wilford D. Raburn

Electrical and Computer Engineering ETDs

Excerpt from the Introduction:

The three terminal PNPN switch which we will refer to as the semiconductor controlled rectifier or SCR has electrical characteristics quite similar to the gas thyratron [7]. In the SCR, current is carried by electrons and holes whereas, in the thyratron, it is carried by electrons and ions. Both have high impedance in the "off" state and low impedance in the "on" state. Both devices will remain in the conducting mode once they have been triggered, even if the gate signal is removed.

The operation of the SCR depends upon the internal feedback mechanism [ 22]. …

A General Approach To The Analysis Of Particle Transport In Solids--With Particular Application To High Frequency Effects On Charge Transport In Semiconductor Devices, Raymond A. Gore

Electrical and Computer Engineering ETDs

The purpose of this first chapter is to review the basis of the diffusion theory description of particle motion in solid material and its application in the analysis of semiconductor devices. Diffusion theory, as used throughout this dissertation, will be used to mean the special case of the more rigorous transport theory that results from assuming an infinite particle velocity and a constant ratio of particle velocity to the probability of a collision. Thus, the discussion of diffusion theory begins with transport theory, and in particular with the Boltzmann transport equation. Therefore, this chapter begins with a formulation of the …

The Effect Of Potential Representation On The Electron Scattering At Low Energies., Ahmed K. Aboul-Seoud

Electrical and Computer Engineering ETDs

One of the most useful approaches for gaining understanding of atomic structure is that of experiments involving electron scattering from atoms. In particular, knowledgle of differential and total elastic scattering cross sections enables one to calculate momentum transfer cross sections, mean free path, and the width of multiple scattering distributions. From the point of view of a theorist, the central question is that of the interaction potential. A representation of this latter quantity will give rise, mathematically, to a two point boundary value problem involving the Schrödinger equation. Upon solving the Schrodinger equation, and satisfying the appropriate boundary con­ditions, the …

Derivation Of Transfer Functions From Time Delay Specifications And Their Approximations., Nasir Ahmed

Electrical and Computer Engineering ETDs

The derivation of transfer functions from given time delay functions. In the sinusoidal steady state, a transfer function may be written as H(jw)= |H(jw)| e^jB(w)

Where B(w) is the phase angle. Then the corresponding time delay function Td is defined as Td = -dB/dw

Galvanomagnetic Effects And Related Phenonmenon In Semiconductors And Dielectrics In A Radiation Environment, Leroy C. Meyer

Electrical and Computer Engineering ETDs

From Introduction:

In 1878, Hall found that the stream lines of an electric current in a metallic conductor were distorted when the conductor was placed in an external magnetic field. This distortion arises from an electric field set up at right angles to the current and to the magnetic field. The effect is well known in conductors and semiconductors, for both steady state and low frequencies Figure 1-1 illustrates the polarities of the Hall voltage for Ix in the direction of conventional current flow.

Transient Response Of Linear Damped Lumped Spring-Mass Systems By Experimentally Derived Transfer Functions, Ralph W. Kelley

Electrical and Computer Engineering ETDs

In the field of mechanical shock testing, there are many instances where the responsive motions of linear undamped and lightly damped lumped spring-mass systems must be determined. If a model representing the system to be tested is available, it is possible to determine the responsive motion by several different approaches. Most of these methods require solving the differential equation of motion in some manner. Among the more common methods of solving the differential equation are the classical solution, the use of Laplace transforms, and various graphical techniques. All of these methods, however, require that a model of the system under …

Directional Effects Of Transient Radiation On Semiconductor Devices, Arthur C. Golubiewski

Electrical and Computer Engineering ETDs

The purpose of this study is to determine the directional effects of transient gamma radiation on electronic components. An analytic expression will be developed for radiation effect as a function of angle, and experiments will be described which verify the mathematical analysis.

The Electrical Conductivity Of Some Cryogenic Fluids, Walter L. Willis

Electrical and Computer Engineering ETDs

Cryogens (liquefied gases with low boiling points) are, in general, excellent insulators. Prior to this investigation, no measurements of conductivity in cryogens had been successful. An upper limit of conductivity in the range 10^-15 to 10^-17 mho/cm had been established for some cryogens. Data from the organic chemicals and petrol m industries indicated that fluids with conductivities in the 10^-11 to 10^-15 mho/cm range could present electrostatic potential hazards, particularly in situations of large volume storage and high flow rates. The advent of large capacity dewars and associated high flow rates of cryogens in the aerospace …

A Mechanical Thevenin Equivalent Circuit Of A Separately Excited D.C. Motor, Hershel R. Lung

Electrical and Computer Engineering ETDs

This problem is concerned with the transient analysis of a DC machine with constant field excitation. By using the generalized circuit concept and Thevenin's Theorem applied to this concept, the transient behavior of this type of machine can be found from an analysis of a lumped circuit model of the machine. The lumped circuit model is a three port device and as such, the terminal equations describing the relationship between the difference and flow signals at the various ports are nonlinear. The nonlinear terms due to the products of signals in the terminal equations can be eliminated by requiring that …

Small Prolate Spheroidal Antenna In A Dissipative Medium., William Troy Cowan

Electrical and Computer Engineering ETDs

A perfectly conducting prolate spheroidal antenna immersed in a conducting medium is analyzed. It is assumed that the dimensions of the spheroid are small compared to a skin depth in the medium. A gain factor for the antenna as a receiver is computed as a function of the spheroid's axis ratio. The prolate spheroid is assumed to be excited by a circular filament of magnetic current located in the plane of the spheroid's minor axes to approximate excitation by a magnetic toroid. Expressions for the antenna's input admittance and effective length are derived. Some experimental results verifying the derivation of …

Transient Gamma Radiation Effects On Resistors, Harold T. Cates

Electrical and Computer Engineering ETDs

If a resistor in a circuit is exposed to a transient gamma radiation pulse, the condition of the circuit will be modified by passing from its steady state condition before radiation to a state of excitation that will depend upon the intensity and duration of the radiation pulse. When the radiation pulse is over, the circuit will then relax to its previous condition of equilibrium within a characteristic time constant.

When energetic radiation, such as gamma radiation, charged particles, or neutrons, strikes matter, it causes several effects which alter the properties of the target material. Some of the effects that …

Antennas In Or At The Surface Of A Conducting Medium At Vlf, George R. Swain

Electrical and Computer Engineering ETDs

To meet the requirements of a number of military operations and to facilitate some types of geophysical exploration, it is necessary to communicate between points beneath or at the surface of the earth or of the ocean. This need has led to the investigation of antennas for use in or at the surface of conducting media. The purpose of this paper is to briefly survey the previous work on such antennas, to extend the concepts of effective length and other merit factors to antennas in or near a conducting medium, and to analyze the electrical behavior of the toroid and …

An Experimental Determination Of Ultrasonic Wave Velocities In Plastics As Functions Of Temperature, Ned D. Arnold

Electrical and Computer Engineering ETDs

This thesis reports the results of an experimental investigation into the effects of temperature on the velocity of ultrasonic longitudinal acoustic waves through various plastics.

The Driving-Point Impedance Of An Electrically Short Cylindrical Antenna In The Ionosphere, William E. Blair

Electrical and Computer Engineering ETDs

1.0 Since the advent of satellites, there has been con­siderable interest in both military and peacetime uses of satellites as research instruments, communication relays, and transportation vehicles. In most cases, it is necessary to communicate with the satellites for purposes of trans­mitting and receiving information.

A Method Of Process Identification Of Certain Linear Control Systems, Eugene A. Aronson

Electrical and Computer Engineering ETDs

No abstract provided.

A Study Of Electro-Magnetic Wave Propagation In Inhomogeneous Media, Thomas N. C. Wang

Electrical and Computer Engineering ETDs

The central problem of this work will be the development of several approximation methods and the application thereof to the solution of second order linear differential equations which arise in connection with the propagation of electromagnetic radiation in inhomogeneous media. Chapter I is an introduction to the problem. Maxwell’s equations are written down and it is assumed that both σ, the conductivity, and ɛ, the permittivity, are scalar functions or position. Often the above function characterizing some or the properties of matter vary in physical situations. For example, in waveguides, there may be inserted layers of dielectric material along the …

The Multi-Terminal Hall Generator, Sang S. Pak

Electrical and Computer Engineering ETDs

This thesis describes a study undertaken to maximize the Hall generator efficiency. A mathematical solution is obtained for a multi-terminal Hall generator, and an analytical technique is developed for determining the optimum values of parameters to maximize the generator efficiency. An equivalent circuit is developed for an N output-terminal Hall generator, and the efficiency expression is obtained as a function of sample dimension, conductivity and Hall coefficient of the material, and magnetic field strength. Some of the results have been checked experimentally with indium antimonide and fields up to 21.5 kilogauss. An efficiency of 40% was obtained experimentally for a …

A Kerr Cell System For Measuring The Amplitude Of High-Voltage Nonrecurring Pulses, Donald C. Wunsch

Electrical and Computer Engineering ETDs

There are at present several conventional techniques and systems to measure the peak amplitude of high-voltage pulses. Three of the prin­cipal techniques are:

1. Potential dividers in conjunction with some type of low-voltage recording system.

2. High-voltage oscilloscopes with low sensitivity.

3. Sphere gaps with predetermined breakover voltages.

Potential dividers of many types have been developed. These include resistive voltage dividers, capacitive voltage dividers, and combination resistive and capacitive dividers. The different designs have usually been developed to eliminate some error in measurement. Different types of resistive windings have been designed to minimize self-inductance. Shields have been designed to reduce …

Predicting Current Gain Degradation In Npn Silicon Transistors After Irradiation By High-Energy Neutrons, Jerry A. Hood

Electrical and Computer Engineering ETDs

The damage discussed in this report is permanent and remains after all transient ionization has decayed. The damage which predominantly affects the electrical characteristics of a transistor is the creation of "vacancies" and "interstitials" in the lattice structure. These defects are created when an atom is knocked from its position and leaves a vacancy in the lattice. The atom comes to rest in a position out of the lattice structure and is known as interstitial. These atoms are knocked from their positions by the irradiating neutrons or by an interstitial traveling through the crystal. These defects occur in localized clusters …

The Design Criteria Of A Phoswich Transducer., Richard L. Crawford

Electrical and Computer Engineering ETDs

This dissertation is an experimental and theoretical treatise on the design criteria of a phoswich transducer. The major emphasis is on the application in a gamma-ray spectrometer. The conversion efficiency, gamma-ray cross sections, response to charged particles, luminescence decay time, spectral response and physical qualities are discussed, in considerable detail, in making the optimum choices for the inorganic crystal and the organic phosphor which will act as the charged particle anticoincident shield. The effect of the thickness of the anticoincident shield on resolution, the percentage of gamma-rays absorbed, the percentage of gamma-rays that are atten­uated in energy and the lower …

Electric Fields From Airborne Vertical And Horizontal Dipoles At Very-Low Frequencies, A. H. Garry Gibson

Electrical and Computer Engineering ETDs

A gap exists in present-day knowledge of the electric fields in the earth which are radiated from elevated antenna structures in the earth-air-ionosphere waveguide. It is the purpose of this paper to present a method of estimating the electric field at the earth-air boundary, caused by elevated antenna structures, and to show the existence of new phenomena that may lead to an improved design of communication systems.

A Study Of Certain Atmospheric Effects On Radar Accuracy, Kenneth R. Swimm

Electrical and Computer Engineering ETDs

Along with other factors, accurate radar target location is dependent upon a knowledge of the electromagnetic propagation path. The propagation path is a function of the characteristics of the medium through which the signal travels. Advances in the resolution capabilities of modern electronic tracking equipment have led to requirements for more accurate prediction of atmospheric refraction characteristics. The inherent error of the equipment is, in many cases, less than the error introduced by the atmospheric refractive effects. After corrections to observed launch angle and target range have been made on the basis of atmospheric refraction information, residual errors in range …