Engineering Commons^™

A Study Of Thermoacoustic Oscillations At Elevated Static Pressures, Michael Einar Berger

Mechanical Engineering ETDs

An experimental investigation was conducted to determine the effect of high static pressure on a closed thermoacoustic sound generator.

The theory for thermoacoustic oscillations is reviewed and analyzed for the case of elevated static pressure. Design equations for high internal pressure oscillators are developed from the principles of dimensional analysis, and a general de­sign equation is proposed.

A closed double-end thermoacoustic oscillator was designed to withstand high temperatures and pressures and was used in the experimental investi9ation. Both air and helium were used as the working gases.

The results of both the theoretical and experimental investigations show that acoustic sound-pressure …

Semiconductor Nuclear Detectors, Lulio V. Guevara R.

Electrical and Computer Engineering ETDs

For the last 8 years the development of nuclear detectors have been shown to have the best potentialities over the other kind of nuclear counters. In this report we studied in general the characteristics of semiconductor nuclear counters and then we experimented with two types of semiconductor detectors, the surface barrier and the diffused junction detectors. Several materials were analyzed for the fabrication of these detectors. Silicon was finally chosen because of its advantages over other materials for fabrication of semiconductor counters, such as low cost and grade of purity. Silicon wafers, n-and p- type, were obtained from Monsanto Company. …

An Experimental Study Of Soil-Structure Interaction, Stephen Connally Mitchell

Civil Engineering ETDs

Experimental data obtained from a series of static arching tests run on vertically oriented rigid-base cylindrical structures buried in a partially saturated low plasticity soil are presented. The experimental results are compared to an available analytical approach. The axial stiffness of the structure, the confined tangent modulus (stiffness) of the soil, and the applied surface overpressure were varied. The most important measurement in this experimental study was the total load carried by the structure for different values of structural stiffness and soil stiffness. The index properties, as well as the shear strength and angle of internal friction for the soil …

A Soil Stress Gage Evaluation., Caryl Martin Reiff

Civil Engineering ETDs

The static evaluation of a recently developed soil-stress gage, primarily designed for laboratory use in dry cohesionless soils, is presented. Two variations of the same basic soil stress gage design are discussed. Tests were performed to evaluate the gage linearity, temperature sensitivity, and electrical response to applied soil pressure. The gage responded linearly to pressure and the calibration curves remained stable within ± 5 percent over a period of two years. With a 10 ma bridge current, the gage had an output sensitivity of 0.040 mv per psi. Temperature changes produced signals which could not be distinguished from pressure signals. …

Mass Transfer Of Oxygen In Sodium Cold Traps, Charles Clellan Mcpheeters

Nuclear Engineering ETDs

Cold traps have been used extensively for controlling oxygen concentration in sodium systems. Cold traps utilize the positive temperature dependence of the solubility of sodium monoxide in sodium and the resultant precipitation of sodium monoxide at low sodium temperatures. Sodium monoxide precipitation is here assumed to be heterogeneous because of the strong effect of surface area on the precipitation rate shown in previous packless cold trap experiments. Growth of crystals from a super-saturated solution is said to proceed according to the equation

where dm/dt is the rate of mass accumulation on the crystal, k is an over-all mass transfer coefficient …

Joining Graphite To Graphite With Transition Metal Foils, Donald James Sandstrom

Chemical and Biological Engineering ETDs

A study has been undertaken to determine the relationship of metallic-foil joining and joining parameters to the strength of joints in a high-quality extruded nuclear graphite. The materials chosen for investigation as joining materials on the graphite of interest were considered to be representative of the Group IVA, VA, and VIA transition metals and iron. The parameters used for joining yielded either a fully diffused joint, which was not temperature-limited with respect to service conditions or a continuous-carbide-interface joint, which was temperature -limited. The metal chosen from Group IVA for joining was zirconium in the form of 0.0005 in. -thick …

A Study Of Delta Modulation And Its Application To Control Communication, Robert H. Maschhoff

Electrical and Computer Engineering ETDs

This thesis is a study of certain aspects of delta modulation which are of particular interest or significance in control system communication. Delta Modulation is a discrete difference encoding method in which the amplitude difference between the signals occurring at two points in time can be transmitted as a plus one or a minus one bit. Such a method of encoding has a rate of change capacity limit rather than a hard amplitude bound.

A determination of the sampling rates, and therefore bit rates, necess­ary to encode several types of signals is reported. Signals which themselves have a rate-limited characteristic …

Magnetic Control Of Carrier Concentration In Semiconductors, S. Lee Hight

Electrical and Computer Engineering ETDs

Magnetic control of carrier lifetime in semiconductors has been examined from a standpoint of applying this phenomenon to low-voltage, high-current switching devices. The continuity equation is extensively examined for intrinsic semiconductors, and limits are derived on the magnitude of the switching effects in terms of material parameters. Experiments have been conducted on undoped indium antimonide which tend to verify these limits. A cursory examination is made of the control of the lifetime of injected carriers. The indications are that this effect may be useful in a wider range of materials than the effect in intrinsic semiconductors.

Measurement Of Deformations An A Large Displacement Gradient Field, Lowell P. Martin

Mechanical Engineering ETDs

A summary of the general kinematical theory of finite deformations is presented together with analyses of the specific deformations of sim­ple shear, bending of a block and bending of an initially curved cuboid.

The moiré fringe equations for large homogeneous deformation are developed. The extension to the nonhomogeneous case is presented and specific analyses are given for the deformations noted above. The moiré theory is combined with the results of the large deformation analyses.

Theoretical results are verified by the study of geometrically produced moiré patterns, and by actual experiments conducted on syn­thetic rubber specimens. The experiments included the deformations …

Stress Fluid In The Vicinity Of A Crack, Alfred S. Arcache

Mechanical Engineering ETDs

The purpose of this investigation was to apply the logarithmic hypothesis of the plane elastic dislocation theory to approximate a plane fracture problem. The region of study is essentially elastic except for a very small region in the neighborhood of the crack which is at some undefined plastic state. The model is a large, thin plate, tensile specimen bounded at the interior by a circular hole from which two stable natural cracks are originated. The experimental model was developed by Ju and Shafer, who also obtained the dislocation function along the crack used in the analysis.

The present fracture analysis …

Trends Of Suspended Sediments In The Upper Rio Grande Basin In New Mexico., Vernon W. Norman

Civil Engineering ETDs

Man has been troubled by the sediment in streams for many thousands of years. Any information toward understanding the nature of this sediment should benefit man in his endeavor to cope with it. Available information was used to determine if trends in the annual quantities of suspended sediment exist in the Upper Rio Grande Bas in in New Mexico. The study revealed that trends do exist and quantitative values were determined for the different trend periods. An effort was made to determine the most probable cause or causes for the changes that occurred in the trends. Eighteen years of suspended …

A Technique For Determining Transistor Spall Thresholds., Herbert L. Floyd Jr.

Electrical and Computer Engineering ETDs

ABSTRACT

The purpose of the work described in this report was to develop a technique for determining the mechanical robustness of small electronic components when subjected to short duration stress waves. Techniques employed by other experimenters., which include flyer­plate impaction and pulsed-electron deposition., are difficult to control and to analyze. The procedure described herein overcomes these difficulties by restricting the variables that control accuracy to those which can be precisely measured.

The wave equation was derived and solved for deformable bodies subjected to unidimensional strain. In addition to providing insight into the dependence of high-tensile stress es on stress -wave …

Transient Pulse Transmission Using Impedance Loaded Cyclindrical Antennas, David E. Merewether

Electrical and Computer Engineering ETDs

Two aspects of the problem of pulse transmission using impedance loaded cylindrical antennas have been considered. First, an approximate solution is obtained for the current distribution on a thin cylindrical antenna driven at an arbitrary point along its length. This solution may be applied to an antenna of any length, and its simplicity makes the current distribution rapidly computable. This solution is ideal for the prediction of the transient electromagnetic field radiated when an arbitrary voltage transient is impressed across the input terminals of a long, thin, cylindrical antenna loaded with lumped im­pedances. Second, an antenna synthesis procedure was evolved. …

A Three-Component Force Transducer For Monorail Rocket Sleds, Vincent Warren Gorman

Mechanical Engineering ETDs

A three-component force transducer which permits measurement of the vertical force, the cross-track force, and the roll moment about an axis parallel to the track was developed for use on monorail rocket sleds. For this force system it was found that the maximum allowable load for both the vertical and cross-track components was approximately 28,000 pounds, and the maximum allowable roll moment was approximately 45,500 inch-pounds. The transducer, mounted between the slipper and sled, uses strain gages as component sensing elements. The strain gage bridges were statically calibrated for each component of load the transducer was designed to measure. In …

The Effect Of Transient Ionizing Radiation Upon Schottky Barrier Diodes, Robert H. Schnurr

Electrical and Computer Engineering ETDs

The theory of operation of the Schottky barrier diode was reviewed. The complications caused by a more accurate space charge formulation were discussed. Consideration of image effects, tunneling, interfacial dielectric layers, surface states, and minority carrier current was also included.

The interaction of ionizing radiation with semiconducting materials was reviewed. The behavior of a Schottky barrier diode in an ionizing radiation environment was considered. The resultant model for the Schottky barrier diode is analogous to a p-n diode with one side having a very high dopant concentration.

Tests were performed upon GaAs and silicon Schottky barrier diodes, using a 2 …

Behavior Of Reinforced Concrete Deep Slabs Subjected To A Uniform Load., Golden E. Lane Jr.

Civil Engineering ETDs

Within the last ten years a considerable amount of research has been conducted to determine the behavior of reinforced concrete deep

structures. The major portion of this recent research has been devoted to deep beams. The results have shown a marked difference in the behavior of deep beams as compared to beams of “normal” proportions. In

this context the word "deep" implies a small span-to-depth ratio. There is not a clear-cut distinction between a "normal-depth" and a deep struc­ture; however, span-to-depth ratios less than ten would suggest deep structures. The difference in behavior between deep beams and normal depth beams …