Engineering Commons^™

Stability Analysis Of Closed Surge Tanks By Phase-Plane Method, Mostafa A. Sabbah

Civil & Environmental Engineering Theses & Dissertations

The governing equations describing water level oscillations in a closed surge tank with compressed air at the top of the tank are a set of nonlinear ordinary differential equations if the hydraulic system is analyzed as a lumped system. These oscillations are stable or unstable depending on the parameters of the plant and the type and magnitude of the disturbance.

The present available stability criterion has been developed by linearizing the governing equations and is, therefore, valid only for small disturbances.

In the research reported herein, the governing equations are normalized to reduce the number of parameters from nine to …

Speech Spectral Modeling And Speech Synthesis Using Finite Impulse Response Digital Filters, Paul Edward Gordy

Computational Modeling & Simulation Engineering Theses & Dissertations

Synthetic speech can be produced using a discrete-time model of human speech production. This model depends on the use of digital filters to model the spectral characteristics of the vocal tract. Speech spectra can be efficiently encoded using a set of principal components basis vectors; however, these vectors are not in a convenient mathematical form for directly determining a digital filter for the speech production model. If discrete cosine basis vectors are used to approximate the principal components basis vectors, then the cosine basis vector coefficients can be used to determine a Finite Impulse Response(FIR) digital filter for speech spectral …

Comparison Of Steady-State Pipe Network Computer Programs, Michael Bernice Holloway

Civil & Environmental Engineering Theses & Dissertations

Four widely used computer programs for the analysis of steady state flows in pipe networks are compared. These programs are NEWTH, written by Jeppson; KENTUCKY, written by Wood; FLOW, written by Epp and Fowler; and LIQSS, written by Stoner. Differences, similarities, advantages and disadvantages of these programs, and various options available are discussed for the benefit of possible future users. In addition, the efficiency of NEWTH, KENTUCKY, and FLOW was tested by simulating a typical network by each program. The listing of LIQSS was not available, and thus was not included in this comparison. In simulation, KENTUCKY used over twice …

Interaction Of A Two-Dimensional Transverse Jet With A Supersonic Mainstream, Gilbert Otto Kraemer

Mechanical & Aerospace Engineering Theses & Dissertations

A experimental investigation of the interaction of a twodimensional sonic jet injected transversely into a confined main flow has been conducted. The main flow consisted of air at a Mach number of 2.9. The effects of varying the jet parameters on the flow field were examined using surface pressure and composition data. Also, the downstream flow field was examined using static pressure, pitot pressure, and composition profile data. The jet parameters varied were gapwidth, jet static pressure, and injectant species of either helium or nitrogen. The values of the jet parameters used were 0.039, 0.056,and 0.109 cm for the gapwidth …

An Approach For Including Reliability In Control System Designs, Ime Isaac Akpan

Mechanical & Aerospace Engineering Theses & Dissertations

An approach is developed for non-catastrophic control component failure accommodation for large space structures. Reliability is considered for both the control configuration (i.e., selecting actuator locations over an admissible set) and the ultimate operation of the system. The approach presented is to construct a measure of performance that indicates the absolute goal of the system, and for a given structural design, to determine the lowest achievable cost conditional upon the failure states of the system (i.e., which actuators are operational). These costs are then weighted and summed to provide an overall system performance measure. This expected performance measure is then …

An Investigation To Model Radar Backscatter From Ridged First Year Sea Ice, Betty Lou W. Jackson

Electrical & Computer Engineering Theses & Dissertations

This thesis investigates the response of a radar type sensor, the microwave scatterometer, to meter scale roughness of first-year sea ice. The scatterometer measures the absolute backscattered power from a target, and use of the radar equation permits calculation of the surface reflectivity expressed as the radar scattering coefficient, σ⁰ also called the normalized radar cross section. This thesis develops an empirical, one dimensional model to predict the backscattered power from ridged first-year sea ice of known surface topography, by interpreting the surface as a series of angular facets and summing the proportional power from each facet. The model …

Calculation Of Potential Flow Past Non-Lifting Bodies At Angle Of Attack Using Axial And Surface Singularity Methods, Jin-Yea Shu

Mechanical & Aerospace Engineering Theses & Dissertations

Two different singularity methods have been utilized to calculate the potential flow past a three dimensional non-lifting body. Two separate FORTRAN computer programs have been developed to implement these theoretical models, which will in the future allow inclusion of the fuselage effect in a pair of existing subcritical wing design computer programs.

The first method uses higher order axial singularity distributions to model axisymmetric bodies of revolution in an either axial or inclined uniform potential flow. Use of inset of the singularity line away from the body for blunt noses, and cosine-type element distributions have been applied to obtain the …

Application Of Least-Squares Method To The Determination Of Orthotropic Elastic And Photoelastic Constants, R. G. Chermahini

Mechanical & Aerospace Engineering Theses & Dissertations

A least-squares technique is developed in matrix form to determine orthotropic elastic and photoelastic constants. Orthotropic elastic constants are determined by mounting strain gages on a half-plane specimen which is subjected to a compressive concentrated force. Strain values corresponding to a 1000 lb load and coordinates of the points where the gages are located are used as input data to the governing equation of orthotropic elasticity for the model under consideration. Orthotropic photoelastic constants are determined using a transparent composite half-plane model which is subjected to a concentrated load. Photoelastic constants are determined using the coordinates of selected point on …

Development Of An On-Line Computer System For Enzyme Kinetics Studies, Jacqueline R. Thweatt

Chemistry & Biochemistry Theses & Dissertations

The PDP-11/10 minicomputer was interfaced to the Beckman 25 ultraviolet/visible spectrophotometer and this on-line computer system was applied to enzyme kinetics studies. This interface involved hardware equipment to locate, amplify, and transmit the analog signal to an analog-to-digital converter, and software to acquire and store the digital data. Data processing programs were used to calculate kinetic parameters and statistical information from the acquired data.

The Varian Cary 219 ultraviolet/visible spectrophotometer can be readily interfaced to the Apple II Plus microcomputer by hardware equipment which can be purchased from the manufacturer. Various software may also be purchased for use in enzyme …

A Pattern Analysis Algorithm For Wind Ambiguity Removal, Jaime R. Tormos

Electrical & Computer Engineering Theses & Dissertations

Some remote sensing devices, such as satellite microwave scatterometers, produce sampled wind vectors that are accurate in speed and streamline direction, but have a directional ambiguity of 180°. The extraction of information from the two dimensional wind vectors is readily handled using pattern analysis techniques. It is shown that there is sufficient information in the spatial relationships of the generated windstream vectors to recognize the driving meteorological wind patterns. This then leads to the resolution of the wind ambiguity problem. This thesis presents the development of a pattern analysis algorithm that generates a measure of the raw data set that …

Experimental Investigation Of A Direct Expansion Solar-Assisted Heat Pump, James Yau-Jwo Shen

Mechanical & Aerospace Engineering Theses & Dissertations

A direct expansion solar-assisted heat pump, which uses economical bare solar collectors as evaporator, is designed and operated. The experimental results indicate that marked improvement in thermal performance results if the collector/ evaporator temperature is maintained at o0c to 10°c above the ambient temperature. During the course of this investigation, the system thermal performance is determined under various ambient and operating conditions by measuring the incident solar energy flux, refrigerant flow rate, temperature and pressure at various locations in the system. The heat pump coefficient of thermal performance and solar collector efficiency ranging from 2.0 to 3.0 and 40% to …

Improved Finite Element Methodology For Integrated Thermal-Structural Analysis, Pramote Dechaumphai

Mechanical & Aerospace Engineering Theses & Dissertations

An integrated thermal-structural finite element approach for efficient coupling of thermal and structural analysis is presented. New thermal finite elements which yield exact nodal and element temperatures for one-dimensional linear steady-state heat transfer problems are developed. A nodeless variable formulation is used to establish improved thermal finite elements for one-dimensional nonlinear transient and two-dimensional linear transient heat transfer problems. The thermal finite elements provide detailed temperature distributions without using additional element nodes and permit a common discretization with lower order congruent structural finite elements. The accuracy of the integrated approach is evaluated by comparisons with analytical solutions and conventional finite …

Seeded Oscillatory Growth Of Si Over Sio² By Cw Laser Irradiation, G.K. Celler, L. E. Trimble, K.K. Ng, H.J. Leamy, H. Baumgart

Electrical & Computer Engineering Faculty Publications

Extensive seeded epitaxial growth of crystalline Si over SiO₂ was achieved by an oscillatory regrowth method applied to rectangular Si pads recessed into a thick SiO₂ film. Narrow (≃5 μm) via holes linked the pads with the bulk (100) Si substrate. Oriented single crystals propagated as far as 500 μm from the seeding area, following the long term advance of a scanned focused laser beam.

Electrical And Structural Properties Of P-N Junctions In Cw Laser Annealed Silicon, M. Maier, D. Bimberg, G. Fernholz, H. Baumgart, F. Phillipp

Electrical & Computer Engineering Faculty Publications

Depth profiles of the electrical quality of ion implanted and cw laser annealed p-n junctions in silicon are obtained for the first time by secondary ion mass spectroscopy. A comparison with the crystallographic properties of the surface and the junction as observed by Nomarski optical microscopy as well as cross-sectional and plan view transmission electron microscopy is made. Samples containing slip dislocations show better insulation and a lower reverse bias current across the p-n junction as compared to samples with a perfect surface in agreement with current-voltage characteristics. Small dislocation loops located at the junction are found to degrade the …

Experimental Investigation Of A Rectangular Surface Thermal Plume, Li-Cheng Chu

Mechanical & Aerospace Engineering Theses & Dissertations

An experimental investigation of the three dimensional mean temperature distribution of a rectangular buoyant surface thermal plume has been conducted for a range of buoyancies, velocity ratios, Reynolds numbers, and for various turbulence generating screens in the crossflow. This study has been motivated by a concern about the applicability of laboratory model data for predicting prototype plume behavior.

A large scale model has been built to study a buoyant, rectangular surface thermal plume which enters at right angles to a constant temperature uniform crossflow of depth equal to that of the plume. A large water tank and flume with weir …

Analysis Of Aerothermodynamic Environment Of A Titan Aerocapture Vehicle, Hsing Chow

Mechanical & Aerospace Engineering Theses & Dissertations

The extent of convective and rad1ative heating for a Titan entry vehicle is invest1gated. The flow in the shock layer is assumed to be axisymmtric, steady, viscous, and compressible. It is further assumed that the gas is in chemical and local thermodynamic equilibrium and tangent slab approximation is used for the rad1ative transport. The effect of slip boundary conditions on the body surface and at the shock wave are included in the analysis of high altitude entry conditions. The implicit finite difference technique is used to .solve the viscous shock layer equations for a 45-degree sphere cone at zero angle …

A Direct Formulation And Computer-Implementation Of A Symbolic Network Analysis Algorithm, Timothy James Knerr

Electrical & Computer Engineering Theses & Dissertations

An algorithm for the symbolic analysis of linear, time-invariant, active or passive networks is presented. The algorithm incorporates the best features of earlier numerical and topological methods of symbolic analysis. A hybrid set of equations is formulated for a closed linear graph and arranged in matrix form. A numerical evalu­ation procedure for the determinant of this hybrid matrix results in an efficient method of symbolic analysis. A proof of the algorithm based on determinant evaluation by a permutation product expansion provides insight into relationships with other methods of symbolic analysis. A computer program implementation of the algorithm is described and …

Water Wave Refraction With Non-Linear Theory, Im Sang Oh

OES Theses and Dissertations

Two different kinds of wave refraction models are formulated in the present study using Stokes' third order wave theory. One type of model is utilized in a parametric study employing several different topographies. Wave trajectories obtained from this model, when obtained by using first and third order wave theory with and without the consideration of energy dissipation, show considerable differences. These differences are examined in more detail for a bottom of constant slope: (1) An approximate 10% difference occurs between the refraction coefficients obtained using the first and the third order wave theory. (2) Considerably different ray trajectories are detected …

Design And Analysis Of A Hybrid Thermoelectric Solar Collector, Kay Eddie Shaheen

Mechanical & Aerospace Engineering Theses & Dissertations

A conventional flat-plate collector is modified by imbedding thermoelectric power generators between the absorber plate and flow tubes in parallel finned-tube passes. As solar energy cascades through these generators a temperature differential between the hot and cold junctions of the device produces direct current electricity. Energy not converted to electric power is converted away for use in domestic space and/or water heating.

A parametric study is performed on the steady-state model via computer program in order to find values of design variables that maximize electric power production for purposes of driving pumps, fans, and ·controlling devices. The results of this …

Photoelastic Investigation Of Load Transfer In Eccentrically Loaded Single Lap Joints, Stephen Antrim Hann

Mechanical & Aerospace Engineering Theses & Dissertations

Photoelastic models of three eccentrically loaded single lap joints were analyzed. The adherends of each joint were identical and the bondlines differed in thickness and material properties. The adherends were analyzed for both cylindrical plate behavior and geometrical nonlinearity and the load transfer efficiency was examined. For all three models it was found that over 98% of the shank behaves as a cylindrical plate and that a geometrically nonlinear analysis yields bending stresses substantially lower than a linear analysis and that a relatively thick, low modulus bondline can increase load transfer efficiency.

Mining The Deep Seabed Implications For International Law And American Foreign Policy, Steven H. Fitzgerald

Graduate Program in International Studies Theses & Dissertations

Whether or not the United States may someday face a mineral shortage, the need for a coherent, unified minerals policy is critical to national objectives and national security. Deep-sea mining may be the answer to American (and world) mineral needs in the twenty-first century. However, there are numerous problems which must be dealt with and resolved in the near future, in order to enable the U.S. (and the world community) to take advantage of vast undersea resources. Deep-sea mining requires the development of technology, tremendous capital investments, and years of labor before production can begin. U.S. policy makers must decide …

Goertler Instability In Compressible Boundary Layers Along Curved Surfaces With Suction And Cooling, Alok K. Verma

Mechanical & Aerospace Engineering Theses & Dissertations

The Goertler instability of the laminar compressible boundary layer flows along concave surfaces is investigated. The linearized disturbance equations for the three-dimensional, counter-rotating streamwise vortices in two dimensional boundary layers are presented in an orthogonal curvilinear coordinates. The basic approximation of the disturbance equations, that includes the effect of the growth of the boundary layer, is considered and solved numerically. The effect of compressibility on critical stability limits, growth rates, and amplitude ratios of the vortices is evaluated for a range of Mach numbers for Oto 5. The effect of wall cooling and suction of the boundary layer on the …

A Method Of Modeling Multirate Two-Dimensional Recursive Digital Filters Author, Albert P. Gerheim

Electrical & Computer Engineering Theses & Dissertations

This dissertation presents a method of modeling two dimensional sampled data systems with two sampling rates in each dimension. This methodology is applied to the problem of synthesizing two dimensional velocity filters using one dimensional prototypes and multirate concepts.

The modeling method includes the replacement of scalar z-transforms of signals by vectors of polynomials, and the replacement of scalar z-transforms of impulse responses by matrices of polynomials.

The synthesis of velocity filters is accomplished through the use of coordinate transformations in the z-transform domain which skew the ω₁ -ω₂ axes on the unit bidisc. The filters synthesized using …

Low Speed Handling Characteristics Of A Supersonic Transport By Eigenstructure Assignment, Michael Peter Lazar

Mechanical & Aerospace Engineering Theses & Dissertations

A synthesis procedure, based upon optimal regulator theory and eigenvalue/eigenvector assignment technique, was used in the design of a low-speed lateral control system for the SCAT-15F supersonic transport. Emphasis was placed on reducing the lateral acceleration at the pilot's station. Control laws were designed to make the aircraft handling characteristics acceptable with the exception of the lateral acceleration. It was found that a compromise between the roll performance requirements and the peak lateral acceleration requirement is needed for a successful SCAT-15F design.

Effects Of Multiple Scattering And Surface Albedo On The Photochemistry Of The Troposphere, Tommy Reinhold Robert Augustsson

Mechanical & Aerospace Engineering Theses & Dissertations

A one-dimensional photochemical model of the troposphere containing the species of the nitrogen, oxygen, carbon, hydrogen, and sulfur families has been developed and used to investigate the vertical profiles and the natural (including atmospheric chemical reactions) and anthropogenic sources and sinks of these species. The species continuity equations are solved numerically applying prescribed boundary conditions. The vertical flux is simulated by use of the parameterized eddy diffusion coefficients. Heterogeneous losses (e.g. rainout, gas-to-particle chemistry, and dry deposition), are parameterized to make calculated profiles consistent with measurements. The photochemical model is coupled to a radiative transfer model that calculates the radiation …

Usage And Limitations Of Characteristic Vector Analysis Of Remote Sensing Multispectral Data For The Identification And Quantification Of Water Quality Parameters, Theodore A. Talay

Civil & Environmental Engineering Theses & Dissertations

Recent applications of the technique of characteristic vector analysis to remote-sensing water color data has met with varying degrees of success. It is apparent from these experiments that a more thorough understanding of the informational capability of characteristic vector analysis is needed.

Sound Absorption In N2-H2o Gas Mixtures At Room Temperature And Low Frequency/Pressure Ratios, William Axam Griffin

Mechanical & Aerospace Engineering Theses & Dissertations

This study was motivated by a need to obtain standard values of nitrogen's contribution to sound absorption in the Earth's atmosphere. Specific goals included accurate measurements of sound absorption in nitrogen - water vapor mixtures at room temperature and low frequency/pressure ratios, the determination of the N₂ vibrational relaxation peak location, (f/P)_max, on the f/P axis as a function of humidity, h, and critical evaluation of all results.

The free decay technique was used in a resonance tube to obtain ten sets of sound absorption data in N₂-H₂O gas mixtures and requisite companion …

Slip Dislocation Formation During Continuous Wave Laser Annealing Of Silicon, Helmut Baumgart

Electrical & Computer Engineering Faculty Publications

High-voltage electron microscopy (HVEM) has been used for the investigation of the defect structure in cw laser-annealed silicon. We report for the first time a (HVEM) analysis of the formation processes involved in the nucleation and glide of slip dislocations during epitaxial regrowth by cw laser annealing of ion-implantation damaged silicon layers. Based on the combined optical and HVEM observations a model of the dislocation generation and glide processes is presented.

High Resolution Laser Absorption Spectroscopy Of Ozone Near 1129.4 Cm-1, Lawrence N. Majorana

Physics Theses & Dissertations

A Beer's Law experiment was performed with a tunable laser to determine self broadened line shape parameters of one infrared absorption ozone line in the v1 band for ten pressures from 0.26 to 6.29 Torr at 285K. SO₂ line positions were used for wavelength calibration. Line shapes were iteratively fitted to the Voigt function at a Doppler width of 29.54 MHz (HWHM) resulting in values for the integrated line• strength, ( S), of (0.144 +/- 0.007 ) x ·10^-20 cm-1/molecule cm-2, line center frequency, (υ_ο) of 1129.426 cm-1 and the Lorentzian contributions to half width, (α …

Sound Absorption In N2-H2O Gas Mixtures At Elevated Temperatures, Roger W. Meredith

Physics Theses & Dissertations

Sound absorption measurements were conducted in N₂ -H₂O gas mixtures at 297, 343, and 387 Kelvin to determine the location of the vibrational relaxation peak of nitrogen on the frequency/pressure, (f/P), axis as a function of humidity and temperature. At low humidities the best fit of the data is to a linear relationship between (f/P)_max and humidity (h) yields a slope of 1 .84 X 10⁴ Hz/ atm mole fraction at all three temperatures. The slope is the same as that reported by Zuckerwar and Griffin (2.00 X 10⁴ Hz/atm mole fraction) but is …