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Air Force Institute of Technology

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A Methodology For Comparing The Value Of Competing Afmc Manpower Allocation Strategies, Sandra K. Smith Mar 1995

A Methodology For Comparing The Value Of Competing Afmc Manpower Allocation Strategies, Sandra K. Smith

Theses and Dissertations

This research effort develops a methodology for Air Force Materiel Command (AFMC) decision makers to use during mandated resource allocation exercises for comparing competing manpower allocation strategies. A value model is used to represent the hierarchical objectives of the command, with the primary objective being the attainment of maximum mission effectiveness in the face of constrained resources. Value model decomposition is patterned according to the command's organizational structure. Scoring functions derived using direct assessment survey techniques capture the relationship between manpower and mission effectiveness for lowest level organizations. An additive value function represents the model mathematically; the primary objective value …

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Spatial Time-Series: Pollution Pattern Recognition Under Irregular Interventions, Samuel A. Wright Mar 1995

Spatial Time-Series: Pollution Pattern Recognition Under Irregular Interventions, Samuel A. Wright

Theses and Dissertations

The Fernald Environmental Restoration Management Corporation (FERMCO) has noted the introduction of arsenic contamination to groundwater around the area of the groundwater recovery system, which captures uranium contaminated groundwater. The introduction of arsenic occurs during high levels of pumping and is particularly sensitive to the western two of the five pumps. Auto-Regressive Moving Average (ARMA) and Spatial-Temporal ARMA (STARMA) empirical analyses are used to model the level of arsenic contamination found through time. The intervention of varied levels of pumping is modeled with a transfer function using analytic techniques to create a causal intervention transfer function input series to give …

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Acquiring Consistent Knowledge For Bayesian Forests, Darwyn O. Banks Mar 1995

Acquiring Consistent Knowledge For Bayesian Forests, Darwyn O. Banks

Theses and Dissertations

This thesis develops a methodology and a tool for knowledge acquisition with the new probabilistic knowledge representation-the Bayesian Forest. It establishes the structure of the Knowledge Acquisition and Maintenance module of the Probabilities. Expert Systems, Knowledge and Inference (PESKI) architecture. The tool, MACK, is designed to be used directly by the domain expert(s) rather than by knowledge engineer(s), and thus supports automated knowledge acquisition. This research determines and implements the constraints necessary to ensure the consistency of Bayesian Forest knowledge bases as data is both acquired and subsequently maintained. The impact to the PESKI architecture of time-dependent information and default …

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Nonlinear Time Series Analysis, James A. Stewart Mar 1995

Nonlinear Time Series Analysis, James A. Stewart

Theses and Dissertations

This thesis applies neural network feature selection techniques to multivariate time series data to improve prediction of a target time series. Two approaches to feature selection are used. First, a subset enumeration method is used to determine which financial indicators are most useful for aiding in prediction of the S&P 500 futures daily price. The candidate indicators evaluated include RSI, Stochastics and several moving averages. Results indicate that the Stochastics and RSI indicators result in better prediction results than the moving averages. The second approach to feature selection is calculation of individual saliency metrics. A new decision boundary-based individual saliency …

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Dynamic Maintenance Scheduling For A Stochastic Telecommunication Network: Determination Of Performance Factors, Todd S. Patterson Mar 1995

Dynamic Maintenance Scheduling For A Stochastic Telecommunication Network: Determination Of Performance Factors, Todd S. Patterson

Theses and Dissertations

This research proposes an analytical approach to access the relationship between maintenance facility location and communication network performance measurement using a selected dynamic maintenance scheduling protocol. There were three objectives established for this effort. The first objective was the determination of an upper-bound upon the level of performance for a telecommunication network using dynamically scheduled maintenance to evaluate maintenance depot location. This was achieved by using a two-stage algorithm, first locate a maintenance depot by using stochastic algorithms, and then to measure the resulting impact upon performance with a multi-commodity network flow model. The second objective was to develop the …

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Visage: Improving The Ballistic Vulnerability Modeling And Analysis Process, Brett F. Grimes Jan 1995

Visage: Improving The Ballistic Vulnerability Modeling And Analysis Process, Brett F. Grimes

Theses and Dissertations

The purpose of this thesis was to improve the process of modeling and analyzing ballistic vulnerability data. This was accomplished by addressing two of the more urgent needs of vulnerability analysts; the ability to display fault tree data and to edit target descriptions. A vulnerability data visualization program called VISAGE was modified to meet these needs. VISAGE was originally created to preview static shotline plots and subsequently grew into a full-featured visualization package for vulnerability target descriptions and analyses data. The next logical step in the programs evolution was to include the needed editing and fault tree display capabilities. The …

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Analysis And Extension Of Model-Based Software Executives, Keith E. Lewis Jan 1995

Analysis And Extension Of Model-Based Software Executives, Keith E. Lewis

Theses and Dissertations

This research developed a comprehensive description of the simulation environment of Architect, a domain-oriented application composition system being developed at the Air Force Institute of Technology to explore new software engineering technologies. The description combines information from several previous research efforts and Architect's source code into a single, comprehensive document. A critical evaluation of the simulation environment was also performed, identifying improvements and modifications that enhance Architecture's application execution capabilities by reducing complexity and execution time. The analysis was then taken one step further and presented extensions to the current simulation environment. The extensions included investigating the feasibility of mixed-mode …

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Multicriteria Mission Route Planning Using A Parallel A* Search, Michael S. Gudaitis Dec 1994

Multicriteria Mission Route Planning Using A Parallel A* Search, Michael S. Gudaitis

Theses and Dissertations

The Mission Route Planning (MRP) Problem falls into the general class of multicriteria path search problems. Multiple criteria are evaluated to select an optimal aircraft mission route through a hostile environment. Criteria for distance travelled and radar exposure are combined into a single cost function for route evaluation. Radar calculations are performed dynamically. The A* search algorithm is applied to the MRP problem, and a parallel implementation is developed and tested. A unique combination of distributed OPEN lists with a global CLOSED list strategy produced fast execution times on the Paragon. Test cases for scenarios with 15 radars took less …

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Performance Characterization Of A Highly-Offset Diffuser With And Without Blowing Vortex Generator Jets, Michael B. Senseney Dec 1994

Performance Characterization Of A Highly-Offset Diffuser With And Without Blowing Vortex Generator Jets, Michael B. Senseney

Theses and Dissertations

The effect of blowing vortex generator jets (VGJs) on the performance of a highly-offset (s-duct) diffuser was investigated experimentally. VGJs are pitched, skewed jets which generate streamwise vortices as well as injecting high-momentum fluid into the boundary layer. Diffuser performance with and without VGJs was measured for an inlet Mach number of 0.6 (Re/x = 1.27x107 per cm). Pitot static and hot-film instrumentation was used to measure flow properties at the diffuser inlet and exit planes. Without blowing, the flow on the lower surface of the diffuser was massively separated. Blowing at 0.48% mass flow ratio through three lower-surface …

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Feasibility Exploration Of Throughfold As A Predictor For Target Loading And Associated Error Bounds, Kris G. Rongone Dec 1994

Feasibility Exploration Of Throughfold As A Predictor For Target Loading And Associated Error Bounds, Kris G. Rongone

Theses and Dissertations

Various applications of the Fredholm integral equation appear m different fields of study. An application of particular interest to the Air Force arises in determination of target loading from nuclear effects simulations. Current techniques first unfold the incident spectrum then determine target loading; resulting spectrum and loading are assumed exact. This study investigates the feasibility of a new method, through-fold, for directly determining defensible error bounds on target loading. Through-fold uses a priori information to define input data and represents target response with a linear combination of instrument responses plus a remainder to derive a quadratic expression for exact target …

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Improving Intrusion Detection In Unix-Based Networks, David R. Landry Dec 1994

Improving Intrusion Detection In Unix-Based Networks, David R. Landry

Theses and Dissertations

Computer security has not kept pace with the rapid growth of networked systems. Through its connection to the Internet, the Department of Defense is vulnerable to computer-based attacks. Current intrusion detection systems are still unproven, too complicated, or too costly for most system security officers to implement. The attack methods used by system intruders are known and can be represented as groups of commands called attack signatures. This thesis investigates methods for detecting intruders by monitoring command usage. Testing was conducted in both controlled and uncontrolled circumstances. With controlled testing, it was shown that 7 of the 11 signatures could …

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The Design And Analysis Of Integrated Navigation Systems Using Real Ins And Gps Data, Curtis D. Evans Dec 1994

The Design And Analysis Of Integrated Navigation Systems Using Real Ins And Gps Data, Curtis D. Evans

Theses and Dissertations

An extended Kalman filter (EKF) is used to combine the information obtained from a Global Positioning System (GPS) receiver and an Inertial Navigation System (INS) to provide a navigation solution. This research compares the results of an actual tightly-coupled GPS-INS integrated system with those obtained in computer simulation. Differences between the simulation and actual hardware results, such as navigation solutions and tuning values, are shown in the research. An analysis of various GPS models was studied to determine the best representation for a system truth model. Measurement updates and their effects upon position accuracies was considered and preliminary research was …

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Satellite Surface Material Composition From Synthetic Spectra, Eugene L. Caudill Dec 1994

Satellite Surface Material Composition From Synthetic Spectra, Eugene L. Caudill

Theses and Dissertations

The objective of this research was to determine if measurements from a Sagnac interferometer could provide reliable estimates of satellite material composition. The Sagnac interferometer yields a spatial interferogram that can sampled by a linear detector array. The interferogram is related to the spectrum of the source through a Fourier transform. Here, spectral reflectivities of nine common satellite materials were used to simulate the spectrum on obtains from an ideal Sagnac interferometer in the beam-train of a ground-based telescope whose mission is to view satellites. The signal-to-noise ratio of the spectrum was varied to simulate the effect of range variation …

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An Experimental Study Of Planar Heterogeneous Supersonic Confined Jets, Frederick J. Tanis Jr. Dec 1994

An Experimental Study Of Planar Heterogeneous Supersonic Confined Jets, Frederick J. Tanis Jr.

Theses and Dissertations

The effects of varying the exit pressure of a supersonic helium jet exhausting coaxially with two parallel supersonic air streams into a constant area duct were investigated. The method used to evaluate the mass entrainment rate was to measure helium molar concentration profiles and mass flux across the duct using a binary gas probe then calculate the mass entrainment into the helium jet. In order to conduct this study a novel binary gas probe was developed which allowed helium concentration and mass flux data to be obtained during continuous traverses across the supersonic flowfield. High exit pressure ratio (EPR) led …

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The Effects Of Transverse Vibration On The Performance Of An Axial Groove Wick Heat Pipe, Kenneth A. Carpenter Dec 1994

The Effects Of Transverse Vibration On The Performance Of An Axial Groove Wick Heat Pipe, Kenneth A. Carpenter

Theses and Dissertations

An experimental investigation was performed to determine the effects of transverse vibrations on the performance of an ammonia-aluminum axial groove wick heat pipe. Theoretical calculations predicted a performance degradation due to the working fluid being shaken out of the upper capillary grooves. A benchtop shaker was used to apply transverse, sinusoidal vibrations of 30, 35, and 40 Hertz, corresponding to peak acceleration amplitudes of 1.84g, 2.50g, and 3.27g, respectively. Maximum heat throughput, Q sub max, of the vibrating heat pipe was measured. A comparison of these values and static Q sub max values indicated a degradation in heat pipe performance. …

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Investigation Of Boundary Layer And Performance Effects Of Transpiration Cooling Through A Porous Plate In A Rocket Nozzle, David N. Keener Dec 1994

Investigation Of Boundary Layer And Performance Effects Of Transpiration Cooling Through A Porous Plate In A Rocket Nozzle, David N. Keener

Theses and Dissertations

This study used a range of low blowing ratios with air through an area of porous material in a Mach 2.0 nozzle to quantity the change in boundary layer thickness as a function of blowing ratio. Also, exit and wall Mach number profiles at each blowing ratio were collected to characterize performance losses as a result of blowing. Performance in terms of specific impulse was also studied. As expected, the boundary layer thickness increased and nozzle performance in terms of exit Mach number decreased with increasing blowing ratio.

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An Investigation Of The Afit 2-Inch Shock Tube As A Flow Source For Supersonic Testing, Kevin M. Vlcek Dec 1994

An Investigation Of The Afit 2-Inch Shock Tube As A Flow Source For Supersonic Testing, Kevin M. Vlcek

Theses and Dissertations

An investigation of the AFIT high pressure shock tube was conducted to determine how closely it followed ideal shock tube theory and to determine the available test times for an attached Mach 3 nozzle. The driver section was five feet (1.52 m) long and the driven section was 25 feet (7.62 m) long. The driver gas used for this study was helium while the driven gas was atmospheric air. The pressure rise measured behind the incident shock wave was, on average, 30% lower than predicted by the ideal shock tube relations. Behind the reflected shock, the pressure rise was 65% …

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Telepresent Spacecraft Docking With Object-Based Bilateral Control (Obbc), Paul Woznick Dec 1994

Telepresent Spacecraft Docking With Object-Based Bilateral Control (Obbc), Paul Woznick

Theses and Dissertations

The concept of object-based control is extended to the field of teleoperation, specifically to accomplish the task of spacecraft docking via a bilateral manual controller. An object-based controller with bilateral feedback controls the motion of the grasped object, not the trajectory of the manipulator. For this reason it can be designed with feedback that is intricately linked with the task kinematics. The benefits derived from anthropomorphicity and force feedback are possible without kinematically-geometrically similar master-slave systems, complex calibration and joint mapping schemes, or expensive, high degree-of-freedom force reflection. Object-based control is ideal for low-level telerobotic interfaces. A hand controller and …

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Stall Precursor Study Of High Frequency Data For Three High Speed, Swept Compressor Rotors, James F. Anderton Dec 1994

Stall Precursor Study Of High Frequency Data For Three High Speed, Swept Compressor Rotors, James F. Anderton

Theses and Dissertations

The frequency spectra of three single stage, high speed compressor rotors were derived and analyzed from experimental data. The compressor rotors included straight, backward-swept, and forward-swept blade designs. Data was acquired from four pressure transducers located on the compressor casing and arranged axially between locations 40% of blade chord upstream of the rotor face to just over the leading edge of the blades. Each rotor was throttled to stall at two constant speeds between 90% and 100% of design speed. Data digitization at 20 kHz revealed multiples of the rotor frequency up to and beyond a dominant blade passing frequency. …

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Investigation Into The Behavior Of Geometrically Nonlinear Composite Arches, John C. Bailey Dec 1994

Investigation Into The Behavior Of Geometrically Nonlinear Composite Arches, John C. Bailey

Theses and Dissertations

This research modifies the existing finite element formulation of a potential energy based large deformation and moderate rotation theory. Hermitian shape functions replace the existing linear bending angle interpolations. Negligible differences between the two formulations indicate the underlying kinematics limit the accuracy, not the finite element interpolations. Using the new program, numerous nonlinear arch geometries are modeled to investigate the effects of arc length and thickness variations. Local and global snapping phenomena are captured as well as through the thickness shear driven nonlinearities.

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Compressible Turbulence Measurements In A Supersonic Flow With Adverse Pressure Gradient, Jon W. Dotter Dec 1994

Compressible Turbulence Measurements In A Supersonic Flow With Adverse Pressure Gradient, Jon W. Dotter

Theses and Dissertations

Mean flow and compressible turbulence measurements have been obtained upstream and within a shock boundary interaction and a compression ramp in Mach 3 flow. Compressible turbulence models have met with little success in the accurate prediction of high-speed flows involving complicated shock boundary interactions and adverse pressure gradients because of a crucial lack of experimental data. Data were collected using conventional Pitot and cone static probes, single overheat cross-wire anemometry, multiple overheat cross-wire anemometry, and flow visualization techniques. Direct measurements of the total Reynolds shear stress were obtained using a turbulence transformation. Results indicate that compressibility effects, as evidenced by …

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Effects Of Blowing Ratio On Heat Transfer To The Throat Region Of A Porous-Walled Nozzle, Joseph L. Lenertz Dec 1994

Effects Of Blowing Ratio On Heat Transfer To The Throat Region Of A Porous-Walled Nozzle, Joseph L. Lenertz

Theses and Dissertations

This experiment analyzed the effects of blowing ratio on heat transfer to the throat region of a porous-walled nozzle, using the AFIT low speed shock tube. Heat flux data were taken from both sides of a two-dimensional Mach 2.0 Re-m=5.2x107 nozzle using thin film resistance thermometers. One side was transpiration-cooled by secondary air injection through a sintered wall, while the other side served as a control. Control results were validated using empirical relations, and cooled side results showed up to a 14% reduction in heat transfer coefficient at blowing ratios of only 0.51%. The linear nature of cooling effectiveness …

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Analysis Of Hypersonic Boundary Layer Second Mode Instability Over A 7° Cone, Richard A. Dennery Dec 1994

Analysis Of Hypersonic Boundary Layer Second Mode Instability Over A 7° Cone, Richard A. Dennery

Theses and Dissertations

This paper presents the results of the analysis of Mach 8.0 flow over a seven degree half-angle cone. The purpose of this analysis was to develop techniques to examine boundary layer transition at hypersonic velocities. The specific objectives were to look for second mode instability waves characteristic of the transition process and to quantify the percentage of turbulent flow. Two sets of data were used in this analysis. The first set of data was taken at several axial positions at a freestream Reynolds number 4.265 million per meter. This data was used to develop the analysis techniques. The second set …

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Experimental Investigation Of The Effects Of Relative Physical Orientation Between Evaporator And Condenser For A Loop Heat Pipe, Brad R. Thompson Dec 1994

Experimental Investigation Of The Effects Of Relative Physical Orientation Between Evaporator And Condenser For A Loop Heat Pipe, Brad R. Thompson

Theses and Dissertations

This research examined the effects on performance of varying angular orientation and height differences between evaporator and condenser for a loop heat pipe. Performance was defined as the difference in temperature between evaporator and condenser (DELTA T). The pipe was evaluated at varying input power (Qin) for: varying evaporator and condenser angles, different coolant temperatures, and varying relative height differences. All analysis included only steady state operation. The performance was influenced by condenser angles, with an optimal condenser angle for best performance being +45 degrees from horizontal. Additionally, the evaporator angles were found to influence performance only at low Qin …

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A State-Space Model Of A Large, Lightly Damped Space Structure Using The Eigensystem Realization Algorithm, Robert D. Woods Dec 1994

A State-Space Model Of A Large, Lightly Damped Space Structure Using The Eigensystem Realization Algorithm, Robert D. Woods

Theses and Dissertations

Large, lightweight space structures of the future will require state-of-the-art vibration suppression systems. To design such a system, it is necessary to have a mathematical model that adequately describes the motion of the system. Coulomb damping compensation was utilized to remove a known nonlinearity from the frequency response functions obtained from the Passive and Active Control of Space Structures (PACOSS) Dynamic Test Article (DTA). Via the Eigensystem Realization algorithm (ERA), the frequency response functions were then used to generate a mathematical representation of the structure's dynamics. Two models were obtained. The first model, without friction compensation, acted as a baseline. …

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Fatigue Behavior Of A Cross-Ply Metal Matrix Composite At Elevated Temperature Under Strain Controlled Mode, Leon B. Dennis Dec 1994

Fatigue Behavior Of A Cross-Ply Metal Matrix Composite At Elevated Temperature Under Strain Controlled Mode, Leon B. Dennis

Theses and Dissertations

This research extends the existing knowledge of cross-ply metal matrix composites (MMC) to include fatigue behavior under strain-controlled fully reversed loading. This study investigated fatigue life, failure modes and damage mechanisms of the SCS-6-Ti-15-3, [O-9O]2s, MMC. The laminate was subjected to fully reversed fatigue at elevated temperature (427° C) at various strain levels. Stress, strain and modulus data were analyzed to characterize the macro-mechanical behavior of the composite. Microscopy and fractography were accomplished to identify and characterize the damage mechanisms at the microscopic level. Failure modes varied according to the maximum applied strain level showing either mixed mode …

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The Collapse Of Composite Cylindrical Panels With Various Thickness Using Finite Element Analysis, Christopher P. Chaplin Dec 1994

The Collapse Of Composite Cylindrical Panels With Various Thickness Using Finite Element Analysis, Christopher P. Chaplin

Theses and Dissertations

This study compared numerical collapse results of graphite-epoxy cylindrical panels with free vertical edges undergoing axial compression for three different shell theories. Symmetric quasi-isotropic laminates were investigated using solid panels and panels with five different centralized cutouts with three thicknesses. The theories compared in the study were the Simplified Large displacement moderate Rotation (SLR) theory, the Donnell Cylindrical Shell (Modified Donnell) theory, and the Classical Donnell theory. The purpose of the study was to determine when large rotations and through-the-thickness shear become important in the numerical collapse analysis of cylindrical composite shells. By observing cases where the numerical collapse results …

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The Design And Development Of A Low-Speed, Low-Force Wind Tunnel Data Acquisition System With An Application To Bicycle Front Fork Spacing, Alan W. Elledge Dec 1994

The Design And Development Of A Low-Speed, Low-Force Wind Tunnel Data Acquisition System With An Application To Bicycle Front Fork Spacing, Alan W. Elledge

Theses and Dissertations

This thesis encompassed the design, development, and application of a low-speed, low-force data acquisition system for the AFIT 5-ft Wind Tunnel. The new data acquisition system was designed and developed to measure approximately 0.045 N (about 0.01 lbf) at nearly 64.4 km/h (40 mph). Verification of the capability was obtained through testing of a cylindrical model. As part of a technology transition program with Wright Laboratory, this new system was used to investigate bicycle front fork blade spacing in order to determine the optimal spacing for minimum drag. As for the minimum drag of a bicycle with an …

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Flight Control Design Using Mixed H2/Μ Optimization, Douglas D. Decker Dec 1994

Flight Control Design Using Mixed H2/Μ Optimization, Douglas D. Decker

Theses and Dissertations

This thesis examines the use of the mixed H2-Microns optimal control synthesis method in the design of a flight control system for the lateral-directional axes of the F-16 Variable Stability In-Flight Simulator Test Aircraft (VISTA). The method is designed to minimize the H2 norm (two-norm) for a given value of microns. This should provide adequate noise and disturbance rejection while maintaining robustness against several types of uncertainties in the system. This thesis finds that, for this problem, the two-norm is not an accurate representation of the outputs of interest. When the two-norm is broken up into its constituent parts an …

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Viscoplastic Characterization And Fatigue Modeling Of Titanium Based Metal Matrix Composites, Mark A. Foringer Dec 1994

Viscoplastic Characterization And Fatigue Modeling Of Titanium Based Metal Matrix Composites, Mark A. Foringer

Theses and Dissertations

Viscoplastic characterization and fatigue modeling of titanium-based metal matrix composites was accomplished by combining a unified viscoplastic theory, a nonlinear micromechanics model, and a linear damage accumulation model. First. Ti 15-3 was characterized using the Bodner-Partom viscoplastic theory. A micromechanics model was then employed in a linear damage accumulation fatigue model to predict the fatigue behavior of titanium based composites. The viscoplastic behavior predictions of the micromechanics model were used to eliminate separately defined time dependent terms in the fatigue model. Also, a new linear damage accumulation model was developed from the fatigue behavior of the composite constituents. Finally, it …

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