Engineering Commons^™

The Effect Of Residual Stress Distribution On The Ultimate Strength Of Tubular Beam-Columns, Steven L. Barrett

Dissertations and Theses

Using data for the longitudinal residual stress distribution in welded steel tubes, curves describing these distributions are selected for study. Each of these curves are checked for static balance across the tube cross section. The curves that exhibit an imbalance are adjusted by a combination of a simplified model for each and the use of a computer program that is developed to calculate the resulting forces and moments on the cross section. The residual stress in the area of the tube wall opposite the longitudinal weld is found to be the most important in the adjustment to obtain exact equilibrium. …

Reduction Of Capacitor Switching Transients By Controlled Closing, John Herman Brunke

Dissertations and Theses

This thesis presents the theory, analysis, testing and implementation of a scheme to reduce shunt compensation capacitor switching transients. The described method is switch the capacitors very near the instant when the bus voltage is at a power frequency zero. This was accomplished with a vacuum breaker on a 230 kV shunt capacitor bank.

Non-Linear Behavior Of Unbraced Two-Bay Reinforced Concrete Frames, Mehdi Shadyab

Dissertations and Theses

In this investigation, the primary objective was to study the nonlinear behavior of unbraced two-bay concrete frames and to determine the extent to which ultimate load theory or limit design can be applied to these structures. The frame behavior was investigated analytically by two methods. In the first method the frame stability equation was derived assuming that members of the frame possess an elasto-plastic moment-curvature relationship. This stability analysis was also carried out by another model consisting of a column attached to a linear spring and carrying the total frame load. The second method was through a computer program which …

The Lb Wind-Tunnel, Larry Bennett

Honors Theses

A small subsonic wind-tunnel has been developed for further understanding of aerodynamic principles. This tunnel is small enough to be used on table tops so the student can get first-hand experience. The tunnel's working section is a clear plexiglass tube for easy viewing and provides ample work room. The biggest advantage of this tunnel is that it can be built in the average home workshop for approximately $60.00.

An Investigation Into The Solution Of Three Dimensional Elastostatic Problems Using The Boundary Integral Technique, David Campbell Aldrich

Retrospective Theses and Dissertations

The boundary integral technique was implemented in a computer code for the general static analysis of three dimensional elastic solids. The was based on a formulation of the problem in which the governing boundary equation is developed from the known solution to Kelvin's problem, by the application of Betti's reciprocal relationship. Modeling the boundary of the region being analyzed with plane elements and assuming the tractions and displacements constant across these elements leads to a set of simultaneous algebraic equations approximating the boundary integral equation. Numerical techniques are used in the computer code to assemble and solve this set of …

A Development Of Regression Models For Predicting Two-Phase Relative Permeability In Consolidated Rock, Mehdi Honarpour

Doctoral Dissertations

"The primary objective of this study was the development of prediction equations for the water-oil imbibition relative permeability and gas-oil drainage relative permeability from experimental data.

Laboratory relative permeability data along with the corresponding rock and fluid properties were collected, and stepwise linear regression analysis was applied. Relative permeability models were developed in terms of rock and fluid properties.

The prediction models were tested against laboratory values and previously published correlations. It was found that the models developed in this study yield results that are generally in better agreement with experimental values than the previously published correlations"--Abstract p. ii

Nominal Molecular Weight Distributions Of Color, Toc, Tthm, Precursors And Acid Strength In A Highly Organic Potable Water Source, Jalil Fouroozi

Retrospective Theses and Dissertations

This research investigated the relationships between molecular size and the TOC, TTHM, acid strength and color concentrations present in raw and coagulated water from Lake Washington. Three separate coagulants were utilized for investigation. There were: Al, Fe and Mg. Results indicated that the majority of the TOC, color and TTHM precursors were in the colloidal size range and removed by coagulation. The remaining TTHM precursors are mostly molecular and require a process other than coagulation for removal from the potable water before environmental standards are met.

Statistical Fading Of A Plane Optical Wave In Atmospheric Turbulence, John F. O'Hara

Retrospective Theses and Dissertations

A formula for the average fade time of the intensity of a plane optical wave traveling through atmospheric turbulence is developed. The model employed involves isotropic, homogeneous statistics using a lognormal distribution for the channel. The analysis is based on the fact that the logarithm of the irradiance is normally distributed and uses the work of S. O. Rice who developed such an expression for a zero mean, Gaussian process. The analysis employs the covariance function and the Taylor frozen turbulence hypothesis which results in an expression for the autocorrelation function.

The Effect Of Shielded Metal Arc Welding Process Variables On Delta Ferrite Control In Austenitic Stainless Steel Weld Metal, Ralph Eldon Long

Dissertations and Theses @ UNI

This study was to determine the effects of shielded metal arc welding on delta ferrite in austenitic stainless steel weld metal. The two objectives of the study were to determine: (a) what variables of the SMAW process affect the delta ferrite content or Ferrite Number of austenitic stainless steel weld metal, and (b) to what extent the Ferrite Number is affected by SMAW variables.

The research design was experimental with data collected from mechanically produced weld metal using a magnetic instrument calibrated in Ferrite Numbers (FN). The electrode alloys tested were 308, 308L, 316L and 347. The sizes of electrodes …

A Multiprocessor System Using A Switch Matrix Configuration, Rabah Aoufi

Masters Theses

"This thesis describes a class of interconnection networks based on the use of a switch matrix to provide processor to memory communication. This switch allows a direct link between any processor to any memory module. The cost and performance of this network are analytically examined. The results are compared with those of a multiprocessor system using a time-shared bus configuration and it is shown that for the two extreme cases of maximum and minimum throughput, the two approaches are equivalent from a performance point of view. However, in the general case, even with a higher cost, the switch matrix provides …

A Monte Carlo Approach To Ridge Discriminant Analysis, Lee Wooldridge

Retrospective Theses and Dissertations

A combined analytical and empirical method to define human performance measures is required for effective automated training. In theory, performance measures can be weighted and combined in a single first order equation upon which an automated training system can track a student's comparative skill level. A form of multivariate discriminant analysis was the statistical technique incorporated into the measurement selection and weighting scheme. (Vreuls and Wooldridge 1977). As with regression analysis, this discriminant technique was subject to debilitating problems such as overfit and undesirable inaccuracies in the coefficients. The author developed and implemented an adjustment to the discriminant function analogous …

Ozonation Of A Municipal Groundwater Supply To Reduce Iron, Manganese, And Trihalomethane Formation, Richard Alan Stoebner

Electronic Theses and Dissertations

The purpose of this investigation was to determine the feasibility of using ozonation followed by filtration for removal of iron and manganese and prevention of trihalomethane formation. To avoid disruption of the treatment plant operation, pilot-scale units were used in the investigation. The filter media and filtering rates employed during the pilot studies were identical to those used at the East Water Treatment Plant.

The General Purpose Interface Bus, Ernest D. Baker

Retrospective Theses and Dissertations

The General Purpose Interface Bus, as defined by the IEEE Standard, deals with systems that require digital data to be transferred between a group of instruments. An overview of this standard is presented which summarizes the interface's capabilities, functions and versatility by explaining the basic interface concepts. In addition, a GPIB testing application and a GPIB related design example are presented and investigated.

A Ten Kilometer Transmission System Fiber Optics Versus Ku-Band, John A. Hallmark

Retrospective Theses and Dissertations

This research paper discusses the design evaluation and selection of a transmission system to be used in checking out the Spacelab high rate data system. The transmission systems evaluated are discussed, as well as the criteria utilized in selecting the final system. The installation of a fiber optics cable and the testing of this cable are discussed. The determination of the optimum location of the high rate data bit synchronizer and Viterbi decoder is presented. Utilization of this data to justify the installation of a shorter fiber optics system inside the O&C Building is presented.

Thermally Stimulated Polarization And Depolarization Current (Tspc/Tsdc) In Glass, Chi-Ming Hong

Doctoral Dissertations

"The feasibility of studying ionic motion in glass using thermally stimulated polarization (TSPC)/depolarization current (TSDC) techniques was investigated with 4Na₂O·96SiO₂ and 30PbO·70SiO₂ (mol%) glasses. The TSDC peaks in these glasses were dependent on glass composition and attributed to bulk polarization. The high temperature background TSPC is shown to be due to dc conductivity, whereas the TSPC/TSDC peaks in the 4Na₂O glass are attributed to shorter range Na⁺ motion.

The electrical conductivity of glasses determined by TSPC agrees well with that measured by conventional ac or dc techniques. The TSPC technique is a rapid and easy method of measuring the …

A Study Of Mechanical Degradation Of A Coarse Aggregate Subject To Repeated Loading, Mark Alan Roenfeldt

Masters Theses

"This investigation concerns itself with the problem of mechanical degradation of a coarse aggregate and specifically as it is used as railroad ballast. Laboratory tests were used to study the aggregate with respect to its plastic deformation characteristics, the amount of degradation, changes in gradation, and the rate of change of degradation as a function of the number of load cycles.

The repeated load triaxial tests were used to study how degradation occurs with respect to aggregate gradation, relative density, and the number of load applications. The Los Angeles abrasion test was also used to determine the degradation of the …

Fade Time Statistics Of Laser Light Propagating Through Turbulent Atmosphere, Madjid A. Belkerdid

Retrospective Theses and Dissertations

The average fade time of the fluctuations in the intensity of laser light propagation in the atmosphere is analyzed. Experimental results show that the average fade time for a propagation distance of 208 meters, in the weak turbulence regime, is well described by formulas developed from a Log-Normal distribution. A circuit that calculates real time statistics of fade time is designed, then validated using a sine wave input whose fade time statistics are predetermined. The experimental signal is then tested for stationarity, and the average fade time is measured. A curve fitting is then performed for the experimental data and …

Design And Analysis Of An Explosive Driven Hydrodynamic Conical Shock Tube, Leonard W. Connell

Retrospective Theses and Dissertations

An explosive driven, water filled, conical shock tube was designed and evaluated regarding its ability to amplify a charge weight and to produce hydrodynamic spherical shock waves. The results show that the shock waves in the tube are essentially spherical in nature--with an initial exponential shape, peak pressure attenuation as (1/R)1.13 and the time constant spreading roughly as (R).22. The charge weight was amplified by a factor of 3600 compared to a theoretical amplification of 7770. An estimate of the energy absorbed by the breach plug (which houses the charge) during an explosion was performed. The peak pressure data taken …

Most Probable Magnetohydrostatic Equilibria For Tokamaks And Reversed Field Pinches, John Joseph Ambrosiano

Dissertations, Theses, and Masters Projects

The determination of magnetohydrostatic equilibria usually requires that two of the equilibrium functions be given. as there is usually no a priori basis for specifying the form of these two functions, the functions and the equilibria they determine may be considered random.;In this dissertation, the author reviews a recent statistical method for determining the equilibrium of an axially symmetric cylindrical plasma which is most probable (in the maximum entropy sense) given four global constraints (i.e., energy, magnetic helicity, longitudinal magnetic flux, and longitudinal current flux). Previous results from this model have been limited to non-negative random equilibrium functions (B(,z), J(,z), …

Petroleum Degradation By Naturally Occurring Populations Of Marine Bacteria From Middle Atlantic Outer Continental Shelf Waters, Alexander Maccubbin

Dissertations, Theses, and Masters Projects

Bacterial populations indigenous to surface (1 m) waters of the Middle Atlantic Outer Continental Shelf were sampled at seasonal intervals to determine the abundance and distribution of petroleum-degrading (HC) and "total" heterotrophic (HET) bacteria. Simultaneously, unweathered South Louisiana crude oil (SLCO) was added to aliquots of surface water samples to evaluate rates and patterns of degradation of hydrocarbon. Degradation was studied using selected nutrient and temperature regimes in both closed flask and prototype "open" or continuous dilution systems. HET bacterial levels generally decreased with distance from land (x inshore = 6 x 10('4) MPN/ml to x offshore = 6 x …

Petrology Of North Mississippi Bauxite : A Case For Depositional Bauxite And Kaolin, Charles Nelson Thompson

Electronic Theses and Dissertations

In the past 55 years, there has been considerable debate over the stratigraphic position, genesis, and economic value of North Mississippi bauxite. The aluminum rich deposits are unlike most deposits found around the world. The deposits are associated with 200-300 foot thick marine to nonmarine clays overlain by feldspar poor, fluvial-deltaic sediments. The possible source areas are composed of limestone, marls, sand, and muds ranging in age from Late Cretaceous to Late Paleocene. These factors prohibit the direct application of previous theories derived from studies outside Mississippi. The deposits, therefore, cannot be considered a textbook example of bauxite formation.

To …

Calcium Migration In Dense Alumina Aged In Water And Physiological Media, Heidi H. Osterholm

Masters Theses

"The flexural strength and relative Ca concentration at the external surface were measured for a dense alumina aged in deionized water and Ringer's solution at 40⁰C for 60 weeks and at 80⁰C for 45 weeks. Changes in the Ca concentration at the external surface and flexural strength during aging were attributed to the dissolution of the calcium impurity believed to be present in a glass phase of unknown composition. Auger electron spectroscopy was used to investigate the relative concentration of the calcium impurity at the external and fracture surfaces of a dense alumina after in vivo exposure for 6, 12 …

Properties Of High Alumina Refractories After Exposure To Steam/H₂ Atmospheres, David W. Lang

Masters Theses

"Selected properties of a dense fired alumina, a phosphate-bonded ramming mix, and a calcium aluminate cement-bonded castable were evaluated after exposure at 260°C and 538°C to steam/H₂ atmospheres (2.58, 5.17, and 6.89) MPa. Chemical reactions in the refractories were determined by x-ray diffraction, DTA/TGA, and changes in physical properties. The modulus of rupture (MOR) of the dense alumina decreased with increasing steam pressure and degree of saturation. The calcium aluminate cement phases in the castable were most reactive in 260°C steam and formed several hydrated phases which generally resulted in a higher MOR. The MOR of the ramming mix …

Aerodynamic Study Of Dual Lifting Surfaces, Kamran Rokhsaz

Masters Theses

"Aerodynamic characteristics of two-dimensional dual airfoil systems have been investigated in an incompressible flow field in the area where improved aerodynamic characteristics are realized, due to the flow field coupling of the two airfoils. A simple analytic model has been developed to demonstrate some of the basic coupling effects in such systems. Laplace's differential equation for the stream-function has been solved numerically to determine the potential flow about dual airfoil geometries of different gap, stagger, and decalage. Two numerical methods have been employed; a finite-difference approach in Cartesian coordinates, for which the mixed boundary conditions have been transformed to the …

An Alternate High Pressure Injection System For Pressurized-Water Reactors, Gary Edward Mueller

Doctoral Dissertations

"To evaluate the In-Core Injection System (ICIS) performance during a loss-of-coolant accident (LOCA) due to a major rupture in the primary system of a pressurized water reactor (PWR), tests were conducted using the thermal-hydraulic computer code RELAP4/MOD5.

The results for the overall plant system show that the maximum core average fuel cladding temperature reached during an intermediate size cold-leg break in a Combustion Engineering PWR with ICIS is equal to the initial operating temperature of 335°c (636°F). The maximum core average fuel cladding temperature reached during a large size cold-leg break with ICIS is 478°c (893°F). This temperature is approximately …

Microwave Sintering Of Batio₃ Ceramics, Kurt Duane Humphrey

Masters Theses

"Barium titanate and BaTiO₃-based multilayer capacitors were sintered in a commercial microwave oven. The oven was equipped with a 2.45 GHz continuous-wave magnetron with a maximum power output of 650 watts.

Microwave-absorbing setters made of SiC were used to offset thermal losses from the samples and allow sintering temperatures (>1325°C) to be achieved. Pure samples were pressed from commercial BaTiO₃ powder and microwave sintered to about 90% of theoretical density. Multilayer capacitors were obtained from commercial manufacturers and used in all sintering experiments. A comparison between microwave sintered material and identical samples sintered in a conventional electric furnace revealed …

Finite Element Model Of A Timoshenko Beam With Structural Damping, Louis Ablen Roussos

Mechanical & Aerospace Engineering Theses & Dissertations

A numerical integration technique, a modified version of the Newmark method, is applied to transient motion problems of systems with mass, stiffness, and small nonlinear damping. The nonlinearity is cast as a pseudo-force to avoid repeated recalculation and decomposition of the effective stiffness matrix; thus, the solution technique is dubbed the "pseudo-force Newmark method." Comparisons with exact and perturbation solutions in single-degree-of-freedom problems and with a Gear-method numerical solution in a cantilevered Timoshenko beam finite element problem show the solution technique to be efficient, accurate, and, thus, feasible provided the nonlinear damping is small. As a preliminary step into the …

Computer Aided Optimal Design Of Helical Gears, S. N. Muthukrishnan

Dissertations and Theses

A random search method for optimum design of a pair of helical gears has been developed. The sequence of optimization consists of two principal components. The first is the selection phase, where the output is the starting solution for the design variables - module, facewidth, helix angle and number of teeth on the pinion. The input for the selection phase includes the application environment, approximate center distance, minimum helix angle, desired values of gear ratio, pinion speed and the power to be transmitted. The limits on each of the design variables and the constraints are imposed interactively during the first …