Engineering Commons^™

Effect Of Surface Conditions On Nucleate Pool Boiling Of Refrigerant-11, Abbas M. Sinnarwalla

Masters Theses

"The purpose of this investigation was to determine the effect of surface conditions on the heat transfer for nucleate pool boiling from flat horizontal surfaces. Experiments were carried out using Refrigerant-11 at atmospheric pressure as the test fluid with Inconel-600 as the heater material. The heat transfer coefficient was determined for mirror finished, chemically etched, glass beaded and sandpaper roughened heater surfaces over heat flux ranging for 0 to 18000 BTU/HR SQ FT. At a given heat flux, the heat transfer coefficient was found to be the lowest for mirror finished surface and the highest for sandpaper roughened surface"--Abstract, page …

The Evaluation Of Radar Guided Missile Performance Using Various Target Glint Models, Franklin Delano Hockett

Masters Theses

"A radar guided missile seeker approaching a target arrives at a crossover point beyond which the entire target is illuminated by the missile seeker's radar antenna beam. When this occurs, for a complex target, the radar senses a time changing target center location which may greatly complicate the terminal tracking portion of the seeker's flight. This thesis documents various glint models in use today and compares the performance of these models by using a seeker model to determine the effect of glint on terminal tracking performance. A large volume of data has been compiled describing various radar characteristics of complex …

Linear Regression Models Of Sound Velocity In The North Atlantic Ocean Below A Critical Depth, Richard Roland Kunkel

Doctoral Dissertations

"Sound velocity models currently in use by the U. S. Navy require difficult data sampling at great expense. This study is to investigate the feasibility of a sound velocity model dependent only upon position that would be valid for a selected, reasonably large, near homogeneous area of the ocean. The most important position parameters are latitude, longitude, and depth. To accomplish this objective a critical depth of 2500 meters was established for an 8° by 20° rectangle of the Sargasso Sea which lies within the North Atlantic Ocean. The critical depth is defined as the depth at which the characteristics …

Some Effects Of Oh Groups On Sodium Silicate Glasses, Mokhtar Sayed Maklad

Doctoral Dissertations

"Glasses of various compositions in the Na₂O-SiO₂ system were prepared with different levels of OH concentration. Phase separation kinetics, thermal expansion, radiation induced optical absorption, and internal friction of these glasses were studied. The increase in OH content in these glasses was found to (a) enhance the rate of phase separation; (b) increase thermal expansion above the glass temperature and change the dilatometric softening temperature in a way that depends on microstructure; (c) increase the radiation induced optical absorption bands associated with positive hole centers and decrease those associated with electron trap centers; and, (d) decrease the low temperature alkali …

Diffusion And Internal Friction In Sodium-Rubidium Silicate Glasses, Gary L. Mcvay

Doctoral Dissertations

"The internal friction and self diffusion coefficients of sodium and rubidium ions for (1 - X) Na₂O·X Rb₂O·3 SiO₂ glasses have been measured. The diffusion measurements employed radioactive isotopes and a thin sectioning technique and extended from 350 to 500°C. Internal friction measurements were made from -150 to 500°C and at frequencies of 0.05 to 6000 Hz. The maximum height for the mixed alkali internal friction peak occurs at the composition where the sodium and rubidium diffusion coefficients are equal. It is concluded that the mechanism responsible for the mixed alkali peak is a cooperative rearrangement of sodium-rubidium ions and …

A Computer Simulation Of Mine Air Shaft Thermodynamics, Ambyo Sumopandhi Mangunwidjojo

Doctoral Dissertations

"Several earlier investigations have been conducted into various aspects of heat problems in underground mines. The application of general gas laws and thermodynamics in the approach of mine ventilation has been helpful in elucidating certain difficulties associated with the subject. By combining several of the techniques perfected by these researchers and applying Carrier's method of calculation for heat flow from exposed rock strata into a workable plan, a method was developed whereby it is possible to accurately and conveniently predict the quality of working environment at any point within a deep mine. The findings of this study may be of …

Voids In Neutron Irradiated Aluminum, Nicholas H. Packan

Doctoral Dissertations

"Void formation in high purity aluminum resulting from irradiation to fluences between 1.5 x 10¹⁹ and 1.6 x 10²² neutrons/cm² (E > 0 .1 MeV) at a temperature of 55 ± 5ºC was studied, primarily by means of transmission electron microscopy. In particular the effects of neutron fluence and flux were examined, as well as the possible influences of both preexisting and transmutation-produced impurities. A very low concentration of voids (about 10¹²/cm³) resulted from irradiation to 1.5 x 10¹⁹ neutrons/cm²; they averaged about 150 Å in diameter. Void concentrations and sizes increased with fluence, reaching values of 6 x 10¹⁴ voids/cm³ …

A Three-Dimensional Mathematical Simulator Of Multiphase Systems In A Petroleum Reservoir, Leonard Koederitz

Doctoral Dissertations

"A generalized digital analysis for calculating three phase, three dimensional flow in reservoirs is developed. The computerized mathematical model is applicable to depletion drive, gas injection, water injection, and/or aquifer drive systems with modifications specific to the simulation criterion of that type of drive and includes fluid compressibility effects, gravity drainage and capillary pressure. The simulation allows arbitrary consideration of reservoir heterogeneity, geometry, well locations and rates of production. An innovation to the alternating direction technique for linear differential equations discussed by Brian is developed and employed in order to render the method of solution applicable to non-linear differential equations. …

An Investigation Of The Stiffness Of Shafts With Integral Disks, Richard King Riley

Doctoral Dissertations

"The results of an investigation of the effect of an integral disk on the torsional elastic stiffness of an axisymmetric shaft are presented. Various configurations of disk diameters and widths on a shaft of specified diameter were investigated, using a finite element method of calculation verified by experimentation. The finite element method is presented for the elastic solution of a general axisymmetric body under all possible axisymmetric load conditions. The axisymmetric body is idealized as an assemblage of triangular cross-sectioned torii representing both the normal and shear properties. The elastic stiffness is used to obtain the equilibrium equations of the …

An Investigation Of Nucleate And Film Boiling Heat Transfer From Copper Spheres, William David Hardin

Doctoral Dissertations

"This study consisted primarily of a laboratory investigation involving nucleate and film boiling heat transfer from copper spheres with saturated liquid nitrogen at atmospheric pressure. An initial study was directed towards obtaining reproducible boiling heat flux versus ΔT curves in the nucleate boiling region from surface conditions created by single and/or multiple glass bead peenings. The variables of bead size, nozzle line operating pressure, and distance a copper surface should be placed from the nozzle outlet were checked. The results indicated that a final peening of the surface with 0.0017-0.0035 inch diameter glass beads, a nozzle line pressure of approximately …

Anodic Dissolution Of Zinc In Potassium Iodide-Potassium Iodate Solutions, Chi-Chiu Yao

Doctoral Dissertations

"The anodic dissolution of Zn was studied in KI-KIO₃ solutions at 25ºC. In I⁻ solutions, it was found that the apparent valence of Zn ions going into solution is approximately two. Smaller values are obtained in IO₃⁻ solutions, with the most pronounced changes occurring in the higher concentrations. An empirical equation is derived relating the apparent valence (or anode efficiency) to the current density and concentrations of IO₃⁻ and I⁻. An anodic dissolution mechanism is proposed"--Abstract, page 1.

Ionization Of Air Produced By Strong Shocks, Howard Sajon Joyner

Doctoral Dissertations

"This dissertation provides theoretical predictions along with experimental results for electron concentrations behind a shock as a function of Mach number over a range from 11 to 20 using a combustion driven shock tube operating in air. These theoretical predictions represent an upper bound for chemical equilibrium. The model for air was 78.0880% nitrogen, 20.949% oxygen, 0.0300% carbon dioxide, 0 .9300% argon, 0.0025%neon, and 0.0005% helium. Also the theory of a double diaphragm shock tube with corresponding pressure ratio vs. Mach number relationships is provided. A computor [sic] program using iterative techniques for a succinct presentation covering the modifications and …

Binary Molecular Diffusivities In Liquids: Prediction And Comparison With Experimental Data, Ronald Dean Mitchell

Doctoral Dissertations

"The Eyring rate theory equation has been modified successfully to enable predictions of binary molecular diffusivities for a wide variety of liquid-liquid systems. The activation free energy for binary diffusion has been evaluated in terms of the activation free energies for self diffusion of the solvent and solute. This was accomplished through the use of regular solution theory by relating the bond breaking energy of the jump step to the bond breaking energy in evaporation. Diffusivities estimated by this equation and the equations developed by Olander, by Gainer and Metzner, and by Wilke and Chang were compared with experimental data. …

Optimizing Diesel Engine Efficiency Using The Controllability Of A Variable Ratio Hydrostatic Transmission, Gordon Wright

Doctoral Dissertations

"A linear mathematical model of a diesel engine, hydrostatic transmission, and electric dynamometer system was developed. This model was used as an aid in designing a single input controller which regulates engine speed to optimize efficiency while maintaining constant transmission output speed under changing load conditions. Compensation was necessary to stabilize the system because of positive feedback in the engine control system. The compensated system's response was compared to that which was predicted analytically. The analytical model was then extended to design the control system parameters to operate the engine and transmission in a representative vehicle"--Abstract, page ii.

A Digital Simulation For Optimum Nonlinear Detection Of Binary Signals In Impulsive Noise, Ralph Bernard Fluchel

Masters Theses

"The problem of reducing the effects of impulsive noise on binary communication systems is considered. A digital simulation of such a system is developed in order to find a nearly optimum (minimum probability of error criterion) nonlinear device to precede detection. The level of the Gaussian noise power is found to be the most important parameter for determining the nearly optimum nonlinear device"--Abstract, page ii.

Efficiency And Loss Mechanism Of The Electro-Fluid Dynamic Momentum Transfer Process Applied To Propulsion Systems Using Atmospheric Air As The Working Fluid, Roger Coy Crites

Masters Theses

"The general equations governing EFD (electrofluid dynamic) flow are established, simplified, and solved in closed form to provide a mathematical model of an ideal EFD propulsion system. This mathematical model, in conjunction with an analysis of ion-neutral and neutral-neutral molecular collision phenomena, indicates that the cause of inefficiency in the EFD propulsion system is the system entropy increase associated with the diffusion of ion momentum through the neutral fluid. This loss mechanism is shown to be analogous to resistive heating losses in a constant voltage linear electrical network and can be minimized by obtaining minimum ion mobility. It is shown …

Next-State Equation Generation For Asynchronous Sequential Circuits - Normal Mode, Gregory Martin Bednar

Masters Theses

"This paper describes the known methods of generating next-state equations for asynchronous sequential circuits operating in normal fundamental mode. First, the methods that have been previously developed by other authors are explained and correlated in a simple and uniform language in order that the subtle differences of these approaches can be seen. This review is then followed by a development of a new method for generating minimal next-state equations which has some advantages over the previous methods. From the comparison of the previous known methods, it is noted that any one of these methods may be desirable for certain designs …

The Design, Construction And Experimental Verification Of A Split Hopkinson Bar, Woosoon Bai

Masters Theses

"This thesis presents the design considerations for a dynamic loading device utilizing a projectile fired from a tube. Also included is a preliminary investigation of the stress-strain relation, under dynamic loading with the device, for a plaster known as Hydrostone. Design of the unit is based on the split Hopkinson pressure bar originally developed by Kolsky and on a similar unit in use at the Lawrence Radiation Laboratory, Livermore, California. The strain pulses along the pressure bars are sensed by resistance wire strain gages and displayed on an oscilloscope. The oscilloscope traces are photographed and manually digitized for insertion into …

Digital Simulation Of A Signal Conditioner/Bit Synchronizer, Quentin Reed Webb

Masters Theses

"A bit rate filter type signal conditioner/bit synchronizer used in a split-phase PCM system is modeled digitally in three stages to determine overall system performance. General computer algorithms are developed to approximate independent operation of each major segment within the device. Bit rate effects and signal time-base error are investigated yielding the characteristic G-curves for the phase detector. These characteristics facilitate subsequent analysis of a linear equivalent digital-data-transition tracking phase-locked loop under several typical time-base error input conditions. Using bit error probabilities as performance criteria, the conditioner/synchronizer is found to perform adequately at signal-to-noise ratios exceeding +10dB. For inputs below …

Bound-Free Continuum Radiation From Non-Gray Nonisothermal Shock Layers, Chu Yih Wang

Masters Theses

"This study investigates the continuum radiative flux from nonisothermal stagnation shock layers composed of atomic gases. The general equations for the composition are derived and the Rankine-Hugoniot equations are simplified and solved to give the thermodynamic conditions of the shock layers. To accurately model the stagnation shock layer, the plasma must be considered to be nonisothermal. In the current study, linear shock layer temperature profiles are assumed. Consequently, the fluid dynamics and the radiation are uncoupled. The radiation model assumes one-dimensional radiative energy transport and considers only continuum processes. The radiative flux is calculated by considereing ground to free state …

Computer Time-Sharing (T-S) "An Engineering Tool" For The Engineering Applications Of The Small Company, James Binford Summers

Masters Theses

"The objectives of this investigation were to illustrate the capabilities of the time-sharing (T-S) industry, identify the means by which the small sized company, with a need to solve engineering problems, can best be served through T-S, and to present T-S to these potential users. Investigation was made of distinctive T-S services to formulate a composite of the T-S industry. Examples of three distinctive T-S services were used within this composite to exemplify the variations of services within the industry. The methods a small company could use to utilize computer services were identified emphasizing T-S as the method best suited …

The Influence Of A Carbon Ablation Layer On Radiation From A Hydrogen Shock Layer, Birbal Singh

Masters Theses

"The effect of ablation heat shields on the radiative heat transfer to vehicles entering hydrogen atmospheres at thermo-dynamic conditions similar to those expected in Jovian atmospheres is investigated. The shock layer is assumed to consist of two plane parallel layers, one consisting of pure hydrogen species, and the other consisting of carbon species only. Each layer is assumed to be in local thermodynamic equilibrium at its respective temperature. The thermodynamic conditions in the hydrogen layer are arrived at by solving the Rankine-Hugoniot Equations across the shock. The temperature of carbon layer is taken as (3000, 5000, and 7000ºK) to cover …

Heat Transfer Through A Spherical Gas Shell, Adel Nassif Saad

Masters Theses

"The radiative transfer through an absorbing-emitting gas shell contained within black concentric spheres at uniform but different temperatures was investigated. A close form exact solution and an approximate solution were derived for the case of isothermal gas layer. The two solutions appear to compare well specially at low diameter ratios, and both agree with the radiative equilibrium solution in the thin limit. An approximate method was developed for the radiative equilibrium, non-isothermal gas layer, of the above problem. The method is based on the assumption of a hyperbolic emissive power distribution through the gas shell. The jump boundary conditions were …

Investigation Of The System Al₂O₃-Teo₂-O₂, Vera Zelenkova Sestak

Masters Theses

"The system Al₂O₃-TeO₂-O₂ has been investigated by X-ray diffraction and differential thermal analysis in air and in sealed silica ampoules. The tellurate, Al₂TeO₆, with tellurium in the +6 valence state, forms in air but not in vacuum at 1 mm pressure. A second phase, a tellurite, possibly Al₂Te₂O₇, forms in air or vacuum by devitrification. The glass-forming region is wider than previously stated and is more extensive in vacuum--from 50% to 98% TeO₂. Tentative phase boundaries have been placed for the system in air and vacuum"--Abstract, page ii.

Fracture Surface Energy Determinations Of High Density Polycrystalline Ceramics, Gene Arthur Pahlmann

Masters Theses

"Values of fracture surface energy were measured for steatite, zircon, mullite and four densities of alumina. Rods of these high density materials were cut into thin rectangular specimens which were notched and broken in three-point loading. The resulting load necessary for fracture of the specimens was used to calculate the fracture surface energy of the materials. The value for the steatite was around 20,000 ergs/cm². The values for the zircon and mullite were on the order of 13,000 ergs/cm², and the values for the aluminas ranged from 17,000 to 24,000 ergs/cm²"--Abstract, page ii.

Numerical Solutions Of The Torsional Oscillations Of A Shaft-Flywheel System, Mahendrakumar Ramkrishna Patel

Masters Theses

"The application of the finite-difference technique, the Fourier transform, and the Laplace transform for the solution of a system governed by the one-dimensional wave equation is examined. A specific example consisting of a continuous shaft-flywheel system acted upon by an exciting torque applied at a specific section of the shaft is studied. The exact solution to this example is obtained using the classical method of superposition of modes, and is used as a reference to evaluate the accuracy (in terms of the rms error) and relative efficiency (based on computer time) of three approximate solution methods. A sinusoidal excitation was …

Size Distribution Analysis Of Carbon Black By Andreason Pipette Method, Natarajan Mani

Chemical and Biological Engineering ETDs

There have been several methods commonly used for measuring particle size distribution of particulate systems in the subsieve region, i.e., less than 45 microns. Of the many indirect procedures of particle size analysis, sedimentation methods are among the most satisfactory and most widely used. - The value and appeal of sedimentation techniques are twofold: (1) the equipment required is simple and (2) a wide range of sizes may be measured readily with considerable accuracy and reproducibility. These techniques utilize the dependence of the falling velocities of particles on their size.

This study widely encompasses the various factors involved in the …

The Time-Dependent Transport Of Monoenergetic Neutron In Plane Geometry With Delayed Neutron Production, Nelson S. Demuth Jr.

Nuclear Engineering ETDs

The initial-value problem for the transport of monoenergetic neutrons in slab geometry with delayed neutron production is studied using numerical methods based on the analysis of Kaper. The eigenvalues and eigenfunctions of the transport operator are found by numerical solution of the equations which result from application of the normal mode expansion method. The residual terms in this form of the solution of the initial-value problem are evaluated by direct numerical integrations on the (complex) resolvent set of the transport operator. The results obtained in this study are compared with the results from the method of matched asymptotic expansions.

An Approadch For Suboptimal Feedback Control., Ronald D. Andreas

Electrical and Computer Engineering ETDs

This dissertation presents an approach for achieving suboptimal feedback control of a class of time-invariant systems, with primary emphasis on linear, time-optimal regulator systems. The approach involves the specification of a family of suboptimal feedback control policies that has the unique feature that each policy in the family will produce a stable system and a suboptimal performance that can be measured against optimal performance. In particular, the performance deviation from optimal afforded by any of these policies is parametrically bounded, and by varying the parameter a hierarchy of policies can be determined. For bang-bang systems, the resulting suboptimal controller design …

This Study Consisted Of A Laboratory Investigation Of The Penetration Behavior Of A Footing Supported In A Vibrating Dry Sand, And Located Below The Surface. A Laboratory Model Was Designed To Simulate These Conditions And Testing Was Conducted To Obtain Data Relating The Magnitude Of Acceleration Of Vibration To The Rate Of Penetration And The Magnitude Of Resistance To Penetration Of A Plunger. Accelerations Ranged Between Zero And 1.5 Times The Acceleration Due To Gravity., Baburao Kasmalkar

Civil Engineering ETDs

This study consisted of a laboratory investigation of the penetration behavior of a footing supported in a vibrating dry sand, and located below the surface. A laboratory model was designed to simulate these conditions and testing was conducted to obtain data relating the magnitude of acceleration of vibration to the rate of penetration and the magnitude of resistance to penetration of a plunger. Accelerations ranged between zero and 1.5 times the acceleration due to gravity.