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Multi-Ion Ambipolar Diffusion, Thomas E. Gist
Multi-Ion Ambipolar Diffusion, Thomas E. Gist
Theses and Dissertations
The continuity and momentum equations for electrons and multiple ion species are solved analytically and numerically using a new model for ambipolar diffusion. The general form of the model is valid for any quasi-neutral plasma for which the diffusion approximation is appropriate, including positive or negative ions, arbitrary geometries, and time dependence. The model provides criteria for determining when single ion diffusion theory is appropriate for describing multi-ion discharges, when a multi-ion proportional model is appropriate, and when a multi-ion nonproportional model is necessary. An expression is developed which provides a necessary condition for proportionality and provides the proportionality constant …
Development Of An Analog Mimo Quantitative Feedback Theory (Qft) Cad Package, Richard R. Sating
Development Of An Analog Mimo Quantitative Feedback Theory (Qft) Cad Package, Richard R. Sating
Theses and Dissertations
This thesis describes the development of an analog MIMO Quantitative Feedback Theory (QFT) CAD package for the automation of the multivariable control design process. The CAD package is capable of carrying a design from problem setup through the design process to a frequency domain analysis of the compensated MIMO system. The package automates the selection of the weighting matrix, formation of the square effective plants, the polynomial matrix inverse required to form the equivalent plants, generation of stability, tracking, disturbance, gamma, and composite bounds, loop shaping, design of the prefilter elements, and the frequency domain analysis of the completed design. …
Design Of A Laboratory Computer Interface, Douglas L. Durand
Design Of A Laboratory Computer Interface, Douglas L. Durand
Theses and Dissertations
An interface for the LSI-11 computer was designed and implemented so that the computer supports data acquisition, data reduction, and equipment control. The design includes both hardware and software and addresses both parallel and serial input/output (I/0). The serial interface's hardware is simply a Serial Line Unit card. This card plugs into the LSI-11 bus and provides the signals necessary to interface EIA RS-232 compatible devices. A software utility was developed to allow communication with the serial device and to allow exchange of data files. Routines were written to allow serial I/O through a FORTRAN program. The interface's parallel hardware …
Neutron Fluence And Dose From A Varian Clinic 1800 Accelerator, Richard A. Jackson
Neutron Fluence And Dose From A Varian Clinic 1800 Accelerator, Richard A. Jackson
Theses and Dissertations
The goals of this study were (1) to verify calibration factors determined by previous experiment for relating counts from activated gold foils to neutron fluences, and (2) to use the method to determine neutron fluences under various operating conditions of the Varian Clinac 1800 (18-MeV) electron accelerator at the WPAFB Medical Center. For comparison similar measurements were made of the CGM Saturne 1 at Kettering Memorial Hospital, Dayton, Ohio. Cadmium-difference pairs in a standard graphite pile were employed to verify the counting efficiency of the Geiger-Mueller beta counting system used to count the foil activity. They were also used to …
A Method For Determining Schedule Delay Information In A Channel Cargo Route Network Schedule, Justin E. Moul
A Method For Determining Schedule Delay Information In A Channel Cargo Route Network Schedule, Justin E. Moul
Theses and Dissertations
This research develops a method for measuring schedule effectiveness by determining the amounts of enroute, cargo delay caused by a given aircraft mission schedule. The method is designed to generate information which helps identify flights for which different scheduling might decrease overall cargo delay in the entire network, given that all non-scheduling factors are held constant. The research uses a simplified twelve-airport cargo route network to test the methodology.
A Modal Analysis And Modelling Of A Lightly Damped Large Space Structure, Scott E. George
A Modal Analysis And Modelling Of A Lightly Damped Large Space Structure, Scott E. George
Theses and Dissertations
This study involves the modification to the PACOSS Dynamic Test Article to create a lightly damped representative large space structure with closely spaced, low frequency modes. An experimental modal analysis is performed to recharacterize the low frequency flexible vibration modes. A finite element model is created using MSC/NASTRAN to predict low frequency behavior using both real eigenvalue analysis and frequency response analysis. Then a reduced order model is created and fine-tuned to represent the dynamics of the structure for the identified low frequency modes.
Multiple Model Adaptive Estimation Applied To The Vista F-16 With Actuator And Sensor Failures, Timothy E. Menke
Multiple Model Adaptive Estimation Applied To The Vista F-16 With Actuator And Sensor Failures, Timothy E. Menke
Theses and Dissertations
A Multiple Model Adaptive Estimation (MMAE) algorithm is applied to the Variable Stability In-flight Simulator Test Aircraft (VISTA) F-16 at a low dynamic pressure flight condition (0.4 Mach at 20000 ft). A complete F-16 flight control system is modeled containing the longitudinal and lateral-directional axes. Single and dual actuator and sensor failures are simulated including: complete actuator failures, partial actuator failures, complete sensor failures, increased sensor noise, sensor biases, dual complete actuator failures, dual complete sensor failures, and combinations of actuator and sensor failures. Failure scenarios are examined in both maneuvering and straight and level flight conditions. The system performance …
Wing Rock Prediction Method For A High Performance Fighter Aircraft, Robert C. Nolan Ii
Wing Rock Prediction Method For A High Performance Fighter Aircraft, Robert C. Nolan Ii
Theses and Dissertations
This study is a limited investigation of the nonlinear aircraft behavior known as wing rock. An eight state F-15 model is analyzed using bifurcation theory. The wing rock onset point is identified and small perturbation analysis is used to linearize the equations of motion about this point. The eigenstructure of the model is analyzed and is used to identify the stability modes involved in this motion. A procedure is developed to predict wing rock onset and frequency and the critical stability derivatives involved in this motion are identified. The developed procedure is applied to existing F-4J data and a flight …
Comparison Of Synchronization Techniques For The Afit Direct Sequence Spread Spectrum System, Edward A. Bednar
Comparison Of Synchronization Techniques For The Afit Direct Sequence Spread Spectrum System, Edward A. Bednar
Theses and Dissertations
The purpose of this study is to analyze and evaluate the performance of several code synchronization methods that could be used in the Air Force Institute of Technology's (AFIT) Direct-Sequence Spread Spectrum (DSSS) communication system. These methods include the sliding correlator, transmitted reference, sequential estimation, and three types of matched filters. The matched filters are the baseband matched filter, delay line matched filter, and the convolver. The criteria used for the evaluation of these synchronization methods are theoretical synchronization times and probability of bit-error. Advantages and disadvantages of each synchronization method are described and a method is recommended to be …
Strategic Deterrence In The Post-Start Era, David C. Mccormick
Strategic Deterrence In The Post-Start Era, David C. Mccormick
Theses and Dissertations
With the Soviet Union's fall there have been widespread calls for drastic reductions in the United States military's strategic nuclear forces. Although a major threat to the United States has been greatly reduced, the number of strategic targets will not decrease as rapidly as the number of available weapons. This research considers how the United States should think about strategic forces in the rapidly changing world order of the 1990s. An extensive literature review of deterrence concepts and conventional weapons capabilities is conducted with special attention paid to the role that precision guided munitions played in the 1991 Persian Gulf …
Feature Extraction And Classification Of Flir Imagery Using Relative Locations Of Non-Homogeneous Regions With Feedforward Neural Networks, Kevin L. Priddy
Feature Extraction And Classification Of Flir Imagery Using Relative Locations Of Non-Homogeneous Regions With Feedforward Neural Networks, Kevin L. Priddy
Theses and Dissertations
The classification of forward looking infrared (FLIR) imagery is explored using Gabor transform decomposition and relative locations of non- homogeneous regions combined with feedforward neural networks. A feature saliency metric is developed from a Bayesian sensitivity analysis of feedforward neural networks. This metric is then used to reduce the dimensionality of the feature vectors used to identify FLIR imagery without any degradation of classification accuracy. Several system architectures are developed using a roving window combined with a series of Gabor filters to produce feature vectors for presentation to a neural network classifier. One architecture uses the Gabor filter coefficients to …
Experimental Evaluation Of Incorporating Digital And Analog Integrated Circuit Die On A Common Substrate Utilizing Silicon-Hybrid Wafer-Scale Integration Technology, Philip C. Reamy
Theses and Dissertations
The objective of this research effort was to investigate the implementation of analog circuits in a wafer scale integration system. A test circuit composed of analog and digital subsystems was designed and tested through simulation. IC die containing this test circuit were utilized in the WSI system fabrication. Preliminary investigations were conducted to evaluate the potential improvements to the IC die mounting procedure, a key step in fabricating functional WSI systems. These investigations demonstrated a procedure which produced repeatable results in achieving acceptable planarization of IC die and host substrate surfaces. These investigations also demonstrated the successful application of a …
An Examination Of Hypercube Implementations Of Genetic Algorithms, Andrew Dymek
An Examination Of Hypercube Implementations Of Genetic Algorithms, Andrew Dymek
Theses and Dissertations
Genetic algorithms are stochastic search algorithms which model natural adaptive systems. In support of the development of a genetic search package for AFIT's iPSC/2 Hypercube, this study focused on two problem areas associated with hypercube implementations. Premature convergence occurs when the population becomes dominated by locally optimal, but globally inferior, solutions. Based on an examination of past hypercube implementations, the selection and communication strategies were hypothesized as causes of premature convergence. Experiments to test these hypotheses were conducted on Rosenbrock's saddle, a function often associated with premature convergence. Communication of best solutions led to premature convergence in small population sizes, …
Development Of A Flight Information System Using The Structured Method, Yeong-Lae Kwak
Development Of A Flight Information System Using The Structured Method, Yeong-Lae Kwak
Theses and Dissertations
This thesis documents the development of a database system for the Flight Information System (FIS) of the Korean Air Force. The scope of the FIS is too large to be covered by this thesis. Thus, this thesis covers only the core part of the FIS due to the limitation of time and man-power. This thesis uses the structured method. Structured analysis and structured design techniques are mainly used two techniques. This thesis focused not only the development of the FIS but also the application of the software development method, the structured method, and its tools such as DFD, DD, ERD, …
Satool Ii: An IdefO Case Workbench Using Ada And The X Window System, Betty Topp
Satool Ii: An IdefO Case Workbench Using Ada And The X Window System, Betty Topp
Theses and Dissertations
The objective of this research effort is to perform an object oriented analysis, design and implementation of the graphical user interface (GUI) for the SATool II system. SATool II is a computer Assisted Software Engineering (CASE) workbench developed using Ada and the X Window system. It is designed to serve as an IDEFo graphical project editor and data dictionary editor. IDEF0 is the ICAM Definition Method Zero graphical notation language adopted by the Air Force to produce a function model of a manufacturing system or environment. The Air Force Institute of Technology is conducting on-going research in the use …
Implementation And Analysis Of Np-Complete Algorithms On A Distributed Memory Computer, Joel S. Garmon
Implementation And Analysis Of Np-Complete Algorithms On A Distributed Memory Computer, Joel S. Garmon
Theses and Dissertations
The purpose of this research is to explore methods used to parallelize NP-complete problems and the degree of improvement that can be realized using different methods of load balancing. A serial and four parallel A* branch and bound algorithms were implemented and executed on an Intel iPSC/2 hypercube computer. One parallel algorithm used a global, or centralized, list to store unfinished work and the other three parallel algorithms used a distributed list to store unfinished work locally on each processor. the three distributed list algorithms are: without load balancing, with load balancing, and with load balancing and work distribution. The …
Design And Analysis Of Electrical Circuits That Produce Fractional-Order Differentiation, Richard N. Hughes
Design And Analysis Of Electrical Circuits That Produce Fractional-Order Differentiation, Richard N. Hughes
Theses and Dissertations
Two half-order differentiator circuit designs were investigated and their electrical performance evaluated (Oldham and Oldfield). Initially, each circuit design was computer modelled and simulated using the HSPICE computer analysis program. Then, each circuit design (Oldham and Oldfield) was fabricated with two different component technologies. This resulted in four circuits, realized on printed circuit boards, to be evaluated--Oldham discrete component; Oldham hybrid component; Oldfield discrete component; and Oldfield surface mount component. The characterizations of each circuit's electrical performance is documented with time, phase, gain, noise and spectrum responses. A comparison of each circuit's performance versus the design criteria and computer model …
Numerical Analysis Of Plasma Transport In Tandem Volume Magnetic Multicusp Ion Sources, Todd R. Vitko
Numerical Analysis Of Plasma Transport In Tandem Volume Magnetic Multicusp Ion Sources, Todd R. Vitko
Theses and Dissertations
A one-dimensional fluid model of plasma transport in tandem volume magnetic multicusp ion sources is explored. The model, the positive ion source code pos, by Glasser and Smith, calculates plasma density, drift velocity, electron temperature, and ion temperature in an ion source. The usefulness of the model is limited: (1) The plasma density trend runs opposite to experimental results, and electron temperatures are an order of magnitude higher than experimentally observed. (2) simplification of the reaction chemistry leads to a plasma balance between ionization and outflow instead of the correct balance between ionization and recombination. (3) Wall losses are …
Feasibility Of An Antiproton Catalyzed Fission Fragment Rocket, David S. Hidinger
Feasibility Of An Antiproton Catalyzed Fission Fragment Rocket, David S. Hidinger
Theses and Dissertations
The purpose of this project was to investigate the feasibility of an antiproton catalyzed fission fragment rocket (FFR). The FFR is characterized by the extraction of fission fragments from the fuel, and the utilization of their kinetic energy for thrust generation. A significant drawback to previous FFR designs was the required critical nuclear pile as the fission fragment source. The author examined the possibility of replacing the critical pile with a sub- critical pile driven by antiprotons. Recent experiments have revealed that antiprotons stimulate highly energetic fissions in 238U, with a neutron multiplicity of 13.7 neutrons per fissions. This interaction …
Development Of A System For Survey Of Radon Concentration Of The Dayton Area Using A Liquid Scintillation Counter And Analysis Of The Data, Taewon Kim
Theses and Dissertations
A system to do a large scale survey was developed. The data obtained from the survey was analyzed using a database. The database incorporated an equation for converting cpm into radon concentration pCi/ℓ). The equation of conversion, protocol for measuring radon concentration, survey form, and a database program were modified (from previous theses) or developed for this thesis. The elution time constant, adsorption time constant, and calibration factor were calculated for equation of conversion. Two surveys were during the course of the thesis. On the first survey, the arithmetic average radon concentration with standard error of the mean was 2.9 …
Gamma-Ray Effects Testing In Lawrence Livermore National Laboratory's Nova Upgrade Facility, David H. Marchant
Gamma-Ray Effects Testing In Lawrence Livermore National Laboratory's Nova Upgrade Facility, David H. Marchant
Theses and Dissertations
Gamma ray effects testing in Lawrence Livermore National Laboratory's (LLNL) planned Nova Upgrade facility is examined. Emphasis is placed on converting neutron energy from inertial confinement fusion in to gamma rays while shielding the test objects from neutrons and debris. Although predicted gamma doses in the Nova Upgrade facility are an order of magnitude less than those produced in some current facilities, dose uniformity, the ratio of minimum to maximum gamma dose is predicted to be greater than 0.75 across a larger, 13, 000 cm2, test bed. Peak gamma dose rates are predicted to be on the order …
Exponential Characteristic Spatial Quadrature For Discrete Ordinates Neutral Particle Transport In Slab Geometry, Glenn E. Sjoden
Exponential Characteristic Spatial Quadrature For Discrete Ordinates Neutral Particle Transport In Slab Geometry, Glenn E. Sjoden
Theses and Dissertations
A new discrete ordinates spatial quadrature scheme is presented for solving neutral particle transport problems. This new scheme, called the exponential characteristic method, is developed here in slab geometry with isotropic scattering. This method uses a characteristic integration of the Boltzmann transport equation with an exponential function as the assumed from of the source distribution, continuous across each spatial cell. The exponential source function is constructed to globally conserve zeroth and first spatial source moments and is non-negative. Characteristic integration ensures non- negative fluxes and flux moments. Numerical testing indicates that convergence of the exponential characteristic scheme is fourth order …
Model Of A Nuclear Thermal Test Pipe Using Athena, Mark J. Dibben
Model Of A Nuclear Thermal Test Pipe Using Athena, Mark J. Dibben
Theses and Dissertations
Nuclear thermal propulsion offers significant improvements in rocket engine specific impulse over rockets employing chemical propulsion. The computer code ATHENA (Advanced Thermal Hydraulic Energy Network Analyzer) was used in a parametric analysis of fuelpipe. The fuelpipe is an annular particle bed fuel element of the reactor with radially inward flow of hydrogen through it. The outlet temperature of the hydrogen is parametrically related to key effects, including the effect of reactor power at two different pressure drops, the effect of the power coupling factor of the Annular Core Research Reactor, and the effect of hydrogen flow. Results show that the …
An Examination Of The Feasibility Of A Nuclear-Pumped Laser-Driven Inertial Confinement Fusion Reactor With Magnetically Protected Walls, John M. Jacobson
An Examination Of The Feasibility Of A Nuclear-Pumped Laser-Driven Inertial Confinement Fusion Reactor With Magnetically Protected Walls, John M. Jacobson
Theses and Dissertations
A preliminary design study of a nuclear-pumped laser-driven inertial confinement fusion reactor with a magnetically protected first wall using an advanced DT-ignited, DD-fueled pellet demonstrated the feasibility of such a concept. This paper presents a parametric study of the required energy multiplication in the blanket, the pellet injection rate, and the net efficiency of this is conceptual reactor for advanced pellet yields. A model of the reactor energy balance yields a required energy multiplication of 2.4. A cylindrical design for a helium-cooled blanket demonstrates that natural uranium micropellets in a laser pump region provide a multiplication of 2.9 with a …
Shock Tube Simulation By The Smooth Particle Hydrodynamic (Sph) Method, Luke A. Lorang
Shock Tube Simulation By The Smooth Particle Hydrodynamic (Sph) Method, Luke A. Lorang
Theses and Dissertations
A smooth particle hydrodynamic code (SPHC) is evaluated for performing shock wave simulations by application to 1-D shock tube problems. Results of a shock tube test case with a compression ratio of 10 are compared against a Riemann shock tube problem and theoretical predictions of shock tube behavior to validate the SPH code. A Lagrangian hydrodynamic code is validated in a similar fashion. The resolution capabilities of both codes are compared using 100, 200 and 500 particles for SPHC and 100, 400 and 800 cells for the Lagrangian code. The SPH code exhibits a sharp spike in density at the …
Design Of A Warm X-Ray Radiation Environment For Nuclear Weapons Effects Testing In The Nova-Upgrade Facility, Jeffrey E. Malapit
Design Of A Warm X-Ray Radiation Environment For Nuclear Weapons Effects Testing In The Nova-Upgrade Facility, Jeffrey E. Malapit
Theses and Dissertations
This engineering design project examined the creation of a radiation environment for warm x-ray effects testing in the Nova Upgrade laser facility. With the use of the MORSE Monte Carlo Code and the DABL69 Broad-group cross section library, the ignition of an inertial confinement fusion pellet using D-T fuel in a test cassette was modeled in the Nova Upgrade's target chamber. Various x-ray scattering materials were used in the test cassette to include enriched lithium hydride, polyethylene, liquid hydrogen, liquid helium, and liquid methane. The lithium hydride produced the best warm x-ray doses and least neutron dose. The predicted x-ray …
Design And Construction Of A Channel Electron Multiplier Based Mossbauer Spectroscopy System, Daniel J. Robbins
Design And Construction Of A Channel Electron Multiplier Based Mossbauer Spectroscopy System, Daniel J. Robbins
Theses and Dissertations
A channel electron multiplier (cem) detector system was designed and built to provide a signal to a Mossbauer spectroscopy system in an effort to obtain a better signal-to-noise ratio than achievable with a proportional counter system. Three cems are contained in a vacuum chamber built using standard components. Gamma, rays of 14.4-keV energy from a 57Co source enter from outside the chamber through a window and are absorbed by an 57Fe target near the cems. The target emits internal conversion electrons which are collected by the cems and a Mossbauer spectrometer collects the signal. The system produces a …
Multilayer Perceptrons For Classification, Lisa M. Belue
Multilayer Perceptrons For Classification, Lisa M. Belue
Theses and Dissertations
Techniques for training, testing, and validating multilayer perceptrons are thoroughly examined. Results obtained using perceptrons are compared and contrasted with two multivariate discriminant analysis techniques- logistic regression and k neighbor. Methods for determining significant input features are investigated and a procedure for examining the confidence to place in the significance of these features is developed. Procedures to evaluate the applicability of high-order feature inputs are examined. These methods and procedures are applied to two very different applications. The first application concerns the prediction of Air Force pilot retention/separation rates for input to force projection models. The second application concerns the …
An Analysis Of The Endurance Of Mobile Satellite Command And Control Systems, Steven O. Brown
An Analysis Of The Endurance Of Mobile Satellite Command And Control Systems, Steven O. Brown
Theses and Dissertations
This study investigated the endurance of a single deployed generic mobile space (GMS) command and control (C2) system. Specifically, factors which affect overall system performance were examined. The analysis began with the development of a simulation model for a GMS C2 system. Optimal settings of factor levels were determined by using the model to find peak system endurance and availability. Factors set were field support vehicle (FSV) access, numbers of maintenance personnel, and numbers of spare components available. After optimum values were chosen for these factors, an experimental design was conducted to determine factor effect between maintenance manpower and the …
Transformation Of Combat Data In Support Of Battle Trace, Hyoung-Kyu Choi
Transformation Of Combat Data In Support Of Battle Trace, Hyoung-Kyu Choi
Theses and Dissertations
The purpose of this study was to find an appropriate way of characterizing battle data as a function of time. This study was initially designed to remove the numerical instability problem cited in Barr's battle trace methodology as suggested by TRAC-MTRY. The research focused on the instability problem and identifying/recommending a technique that improved the efficiency of computation, and enhanced an analyst's ability to meaningfully interpret the battle trace. Two Lanchester's Square Law based methodologies are introduced and analyzed. The results of this analysis indicate that the battle trace of a constant value generated by Lanchester's Square Law integration seemed …