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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Computing Norad Mean Orbital Elements From A State Vector, Dwight E. Andersen
Computing Norad Mean Orbital Elements From A State Vector, Dwight E. Andersen
Theses and Dissertations
NORAD maintains and disseminates mean orbital elements on Earth-orbiting satellites in the form of Two-Line Element Sets (TLE). Five mathematical propagator models were developed for NORAD's use to predict the position and velocity using TLEs. This study investigated two approaches, Newton's method and direct iteration, to inverting this process by iterating to obtain NORAD-compatible mean orbital elements from a position and velocity state vector and the drag term. The Newton's iteration method was developed but not tested. The less computationally intensive direct iteration method was developed, coded in FORTRAN, and tested. The initial guess and subsequent corrections in the iterative …
A Numerical Analysis Of Smoothed Particle Hydrodynamics, David A. Fulk
A Numerical Analysis Of Smoothed Particle Hydrodynamics, David A. Fulk
Theses and Dissertations
This dissertation studies the numerical method of Smoothed Particle Hydrodynamics SPH as a technique for solving systems of conservation equations. The research starts with a detailed consistency analysis of the method. Higher dimensions and non-smooth functions are considered in addition to the smooth one dimensional case. A stability analysis is then performed. Using a linear technique, an instability is found. Solutions are proposed to resolve the instability. Also a total variation stability analysis is performed leading to a monotone form of SPH. The concepts of consistency and stability are then used in a convergence proof. This proof uses lemmas derived …
Optimal Pulsed Pumping For Aquifer Remediation When Contaminant Transport Is Affected By Rate-Limited Sorption: A Calculus Of Variation Approach, Richard T. Hartman
Optimal Pulsed Pumping For Aquifer Remediation When Contaminant Transport Is Affected By Rate-Limited Sorption: A Calculus Of Variation Approach, Richard T. Hartman
Theses and Dissertations
The remediation of groundwater contamination continues to persist as a social and economic problem due to increased governmental regulations and public health concerns. Additionally, the geochemistry of the aquifer and the contaminant transport within the aquifer complicates the remediation process to restore contaminated aquifers to conditions compatible with health-based standards. Currently, the preferred method for aquifer cleanup pump-and-treat has several limitations including, the persistence of sorbed chemicals on soil matrix and the long term operation and maintenance expense. The impetus of this research was to demonstrate that a calculus of variations approach could be applied to a pulsed pumping aquifer …
Modeling Of Ground Water Aquifer Remediation By Pulsed Pumping When Contaminant Transport Is Affected By Physical, Non-Equilibrium Sorption And Desorption, Jeffrey L. Caspers
Modeling Of Ground Water Aquifer Remediation By Pulsed Pumping When Contaminant Transport Is Affected By Physical, Non-Equilibrium Sorption And Desorption, Jeffrey L. Caspers
Theses and Dissertations
This research postulates and demonstrates a modification incorporating rate-limited sorption effects in the USGS SUTRA code for cleanup of a hypothetical sandy aquifer by pump-and-treat remediation methods. Contaminant transport is assumed to be affected by advection, dispersion, and rate-limited sorption/desorption. Sorption is assumed to be either equilibrium or rate-limited, with the rate-limitation described by either a first-order law, or by Fickian diffusion of contaminant through a spherical immobile pore region. Solutions are arrived at by split operator methods for the transport and one-dimensional Galerkin solutions for the solute concentration equations. The resulting model is tested against an analytical Laplace transform …
Noise Reduction For Speech Enhancement Using Non-Linear Wavelet Processing, Hassan Dehmani
Noise Reduction For Speech Enhancement Using Non-Linear Wavelet Processing, Hassan Dehmani
Theses and Dissertations
The problem of speech enhancement presents many obstacles in the speech processing field. This thesis develops several speech de-noising systems that can be used in the time, fourier, and wavelet domains. We present two thresholding techniques soft and hard. The application of these thresholding techniques to noisy speech data is discussed. The combination of both wavelets and the Fourier domains with noisy phase restoration proves to yield the best results in terms of intelligibility. Informal listening tests were conducted in order to compare the effects and differences between the speech de-noising systems.
Multirate Time-Frequency Distributions, John R. O'Hair
Multirate Time-Frequency Distributions, John R. O'Hair
Theses and Dissertations
Multirate systems, which find application in the design and analysis of filter banks, are demonstrated to also be useful as a computational paradigm. It is shown that any problem which can be expressed a set of vector-vector, matrix-vector or matrix-matrix operations can be recast using multirate. This means all of numerical linear algebra can be recast using multirate as the underlying computational paradigm. As a non-trivial example, the multirate computational paradigm is applied to the problem of Generalized Discrete Time- Frequency Distributions GDTFD to create a new family of fast algorithms. The first of this new class of distributions is …
An Investigation Of Simulated Annealing Applied To Structural Optimization Problems, Richard C. Mceachin
An Investigation Of Simulated Annealing Applied To Structural Optimization Problems, Richard C. Mceachin
Theses and Dissertations
This thesis investigates the feasibility of using Simulated Annealing SA in structural optimization problems. The investigation involves solving benchmark structural optimization problems with an SA algorithm, and comparing its solutions to those found by four other optimizers. Overall, the analysis shows that SA has limited applicability in structural optimization. Two primary factors were found to adversely impact the performance of the SA algorithm in these problems. These factors are high dimensionality, and high levels of constraint. The difficulty involved in solving these problems with a random search increases exponentially with the number of dimensions. The number, and non-linearity, of the …
An Air Mission Planning Algorithm For A Theater Level Combat Model, Brian J. Griggs
An Air Mission Planning Algorithm For A Theater Level Combat Model, Brian J. Griggs
Theses and Dissertations
This thesis describes the development of an air mission planning algorithm for the Joint Staffs Future Theater Level Model FTLM. The overall problem scope was to develop an algorithm to handle major factors bearing on the combat mission planning problem while providing hook-ups for the FTLM architecture. Other aspects of the problem included finding the appropriate level of detail, developing a fast solving technique, and attempting to use existing data. The problem was handled by using some ideas from existing aircraft allocation algorithms and by adding some new techniques. The proposed air mission planning algorithm supplies the optimum degree of …
Point And Interval Estimation Of Series System Reliability Using Small Data Sets, Craig J. Willits
Point And Interval Estimation Of Series System Reliability Using Small Data Sets, Craig J. Willits
Theses and Dissertations
This investigation explored the relative performance of several small-sample point and interval estimators for series system reliability. Among point estimators, the maximum likelihood estimator MLE was compared to the corresponding Bayes estimator. In addition, four interval estimators were compared Easterlings modified maximum likelihood integer estimator, the Lindstrom-Madden estimator, and Bayesian probability interval estimators constructed using approximate beta and Bayes Monte Carlo empirical posterior densities. The relative performance of the point estimators was assessed by comparing their mean square errors. For the four interval estimators, the interval coverage probability and the average interval lower bound were examined. The values of these …