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Air Force Institute of Technology

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Articles 2971 - 3000 of 3078

Full-Text Articles in Physical Sciences and Mathematics

Photoluminescence Spectroscopy Of Mbe Grown Gallium Antimonide, John A. Dorian Dec 1991

Photoluminescence Spectroscopy Of Mbe Grown Gallium Antimonide, John A. Dorian

Theses and Dissertations

Experimental data are presented for the energy levels of the native acceptor and bound exciton emissions of GaSb grown by MBE and studied with low temperature photoluminescence (PL) spectroscopy. The undoped GaSb emissions showed a donor-acceptor pair transition with an observed emission peak at 776 meV, a peak at 716 meV usually associated with the ionization level of the acceptor, and bound exciton transitions in the energy range from 796 to 804 meV. Other unidentified peaks were observed at about 805 meV. Temperature and power dependence studies of the acceptor peak confirmed donor-acceptor pair (DAP) behavior. A GaSb sample grown …

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Silicon Carbide Thin Film Deposition By Reactive Ion-Beam Sputtering, Larry G. Sills Dec 1991

Silicon Carbide Thin Film Deposition By Reactive Ion-Beam Sputtering, Larry G. Sills

Theses and Dissertations

In this study, hydrogenated amorphous silicon carbide thin films were deposited by reactive ion-beam sputtering under varying conditions to determine whether a film's optical properties can be controlled, focusing on refractive index. Using a Kaufman type ion source to sputter a pure silicon target, three distinct series of films were grown. The first series varied the mixture of methane and argon used in the ion-beam. holding all other parameters constant. For the second series the gas mix was fixed, and only the beam energy (beam voltage) was varied. The final series also varied beam energy, but was grown with a …

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Vibrational Energy Transfer In Bromine Monofluoride, Tim L. Thompson Dec 1991

Vibrational Energy Transfer In Bromine Monofluoride, Tim L. Thompson

Theses and Dissertations

Bromine monofluoride (BrF), an interhalogen molecule, is a prospective chemical laser candidate. This study continues research begun in characterizing radiative and collisional dynamics in BrF. Vibrational energy transfer of BrF is studied using time resolved laser induced fluorescence (LIF) techniques and observing the spectrally resolved emission. First, vibrational transfer induced by the BrF production mix is determined to follow the Montroll- Shuler model and Landau-Teller scaling with a fundamental rate coefficient of kv(1,0) = (4.0) x 10-12 cm3/(molecules seconds). Also, rate coefficients for the rare gases were found to scale with the reduced mass of the collision …

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Radar System Classification Using Neural Networks, David M. Cameron Dec 1991

Radar System Classification Using Neural Networks, David M. Cameron

Theses and Dissertations

This study investigated methods of improving the accuracy of neural networks in the classification of large numbers of classes. A literature search revealed that neural networks have been successful in the radar classification problem, and that many complex problems have been solved using systems of multiple neural networks. The experiments conducted were based on 32 classes of radar system data. The neural networks were modelled using a program called the Neural Graphics Analysis System. It was found that the accuracy of the individual neural networks could be increased by controlling the number of hidden nodes, the relative numbers of training …

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Binary Programming Models Of Spatial Pattern Recognition: Applications In Remote Sensing Image Analysis, Thomas G. Reed Dec 1991

Binary Programming Models Of Spatial Pattern Recognition: Applications In Remote Sensing Image Analysis, Thomas G. Reed

Theses and Dissertations

The major purpose of this investigation was to implement subregion allocation objectives using a network model base on an existing subregion allocation binary programming model (Benabdallah and Wright (B&W), 1990), the ultimate goal being the application of subregion allocation concepts towards the spatial analysis of satellite imagery. The multi-objective aspects of subregion allocation can be accomplished via a network formulation, a formulation vastly simpler in complexity than the binary programming models previously used. Without a network programming package that could maintain integral flows, however, deriving the solution was a tiresome task for the user. Nonetheless, several new concepts and advantages …

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Reducing Requirements Errors Through The Use Of Computer-Aided Software Engineering (Case) Tools And During Requirements Analysis, Marvin B. Key Jr. Dec 1991

Reducing Requirements Errors Through The Use Of Computer-Aided Software Engineering (Case) Tools And During Requirements Analysis, Marvin B. Key Jr.

Theses and Dissertations

This study investigated whether using CASE tools in the requirements analysis phase of software development reduced the software coding errors attributable to requirement analysis. A survey of the population gathered data as to the current practices and efforts in the use of CASE tools. The data was gathered in two groups: a control group and a sample group. The data was analyzed by group and in various combinations to obtain a greater understanding into population trends and tendencies. The results of the research indicate that the Air Force does not use CASE tools to any great extent. Also, error and …

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A Formal Definition Of The Object-Oriented Paradigm For Requirements Analysis, Andrew D. Boyd Dec 1991

A Formal Definition Of The Object-Oriented Paradigm For Requirements Analysis, Andrew D. Boyd

Theses and Dissertations

This paper develops a formal definition of the Object-Oriented paradigm for requirements analysis. The literature was surveyed for both formal and informal methods for conducting an Object-Oriented Requirements Analysis (OORA). The informal methods reviewed are: Bailin's, Shlaer and Mellor's, Booch's, and Coad and Yourdon's. The formal methods reviewed are: Bralick's, Z, and REFINE. None of the methods were found to be adequate for doing an OORA. A formal definition of an OORA, based on the concept of classes, is developed. The definition itself is presented as set and relation theory. A supporting graphical representation is also developed and presented. The …

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Investigative Search Of Quality Historical Software Support Cost Data And Software Support Cost-Related Data, Brent L. Barber Dec 1991

Investigative Search Of Quality Historical Software Support Cost Data And Software Support Cost-Related Data, Brent L. Barber

Theses and Dissertations

The purpose of the study was to determine what software support cost data and software support cost-related data should and can be collected by the Air Force. In addition, the study was to determine how the subject data should be collected. The collection of this data is necessary in order to measure the accuracy and calibration requirements of the software support cost models used by the Air Force. The study found there was no standard set of data items, and no standard procedures in place for the collection of this data. In most cases data were available or easily accessible, …

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Structured Hypermedia Application Development Model (Shadm): A Structured Model For Technical Documentation Application Design, Peter W. Cassell Dec 1991

Structured Hypermedia Application Development Model (Shadm): A Structured Model For Technical Documentation Application Design, Peter W. Cassell

Theses and Dissertations

This research was conducted to determine how a Royal Australian Air Force technical maintenance publication could be transformed into a task oriented hypermedia application and to develop a model that could be used for future similar transformations. The model was developed following in-depth analysis of the existing USAF F-15E maintenance publication set and validation was conducted using a prototype developed in HyperWriter, a commercial hypermedia product. The prototype model was based around the performance of three maintenance tasks on an aircraft sub-subsystem and incorporated online user access to the necessary support data for task completion. Publication managers, producers, and users …

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Relative Utility Of Selected Software Requirement Metrics, James H. Byers Dec 1991

Relative Utility Of Selected Software Requirement Metrics, James H. Byers

Theses and Dissertations

The objective of this study was to determine the relative utility of selected software requirement metrics in assessing the productivity of the software requirements analysis process and the quality of the products of this process. This objective was met by collecting information about the perceptions that practicing software professionals have of the usefulness of various requirement metrics. The study employed a two part methodology. The first part utilized Basili's goal/question/metric paradigm to identify specific goals of the measurement effort and to identify requirement metrics worthy of further investigation. The second part employed a typical research design to gather perceptions that …

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Computation Of Planar Store Trajectories Using An Adaptive Grid Procedure, William D. Hack Dec 1991

Computation Of Planar Store Trajectories Using An Adaptive Grid Procedure, William D. Hack

Theses and Dissertations

The objective of this research was to compare a quasi-analytical, potential flow/three-degree-of-freedom model to an implicit-Euler algorithm for the calculation of store trajectories. The implicity algorithm uses a cell- centered, finite-volume, spatial discretization applied to the Euler equations, written in time-dependent, curvilinear-coordinates. A flux-differencing Roe scheme is employed to find the split-fluxes and the Steger/Warming flux-vector method is used to calculate the flux-Jacobians. The potential flow and implicit- Euler algorithm are combined with a three-degree-of-freedom algorithm to evaluate the planar, freefall trajectories of a simple store shape. The research uses two different grid-modification techniques in the implicit algorithm evaluation. Data …

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An Expert System Advisor For Medical Evaluation Boards, Jerry S. G. Harrington Dec 1991

An Expert System Advisor For Medical Evaluation Boards, Jerry S. G. Harrington

Theses and Dissertations

Expert system technology has proven itself to be able to improve productivity and decision making in a variety of fields of endeavor. The purpose of this study was to determine if an expert system for medical evaluation boards (MEBs) could improve upon the processing of medical evaluation board cases. Research was conducted to develop an expert system and measure the capabilities of the system, both in terms of accuracy and timeliness of case completion of the medical evaluation administrators/clerks who were assisted by the system. The research methodology involved a three - phase approach. The objective of phase one was …

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An Algorithm For Robust Eigenstructure Assignment Using The Linear Quadratic Regulator, Thomas C. Huckabone Dec 1991

An Algorithm For Robust Eigenstructure Assignment Using The Linear Quadratic Regulator, Thomas C. Huckabone

Theses and Dissertations

The Linear Quadratic Regulator (LQR) can guarantee a robust closed loop eigenstructure for full state feedback. The algorithm developed here takes advantage of the stability guarantees of LQR to achieve an eigenstructure close to desired but within the allowable region of LQR. The algorithm selects the LQR weighting matrices, Q and R, that minimize the distance between the elements of the desired and LQR achievable eigenstructures. The minimization is accomplished by using a simplex based optimization routine. Specific weightings placed on the elements of the desired eigenstructure define the relative importance of each element. The algorithm is programmed in FORTRAN …

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Logic Programming In Digital Circuit Design, Joseph W. Eicher Dec 1991

Logic Programming In Digital Circuit Design, Joseph W. Eicher

Theses and Dissertations

The design of large, complex digital circuitry requires highly skilled engineers. Much of the time spent by these engineers in the design phase involves tasks that are repetitive, tedious, and slow. If these repetitive tasks are automated, the engineer can spend more time managing the design process and produce a better-quality design in less time. Logic programming can be used to automate design tasks, even those that require a high degree of skill. This thesis investigates several aspects of the digital circuit design process that involve pattern-matching paradigms suitable for encoding in the logic programming language Prolog.

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Discrete Simulation Of Fractional Order Systems, Jeffrey A. Blank Dec 1991

Discrete Simulation Of Fractional Order Systems, Jeffrey A. Blank

Theses and Dissertations

Fractional calculus has been shown useful for describing many real world systems, and studies are currently underway to generalize control theory to incorporate fractional states. This investigation derives a method for simulating the time response of fractional order systems using a recursive difference equation. The technique used effectively approximates a simple fractional order integrator as a summation of integer order terms. The discrete transfer function is also derived and the frequency response of the discrete algorithm is compared to the exact continuous case. Using 20 or more retained past values in the difference equation, the discrete half-order integrator demonstrates a …

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The Application Of Kriging For Controlled Minimization Of Large Data Sets, Christopher Brodkin Dec 1991

The Application Of Kriging For Controlled Minimization Of Large Data Sets, Christopher Brodkin

Theses and Dissertations

Frequently, the quantity of data available is much greater than that which can be manipulated in an efficient and timely manner. This can cause several problems. The first, and probably most critical, problem is the excessive on-line storage needs of these huge data sets. Secondly, in the computer animation field, huge data sets may require excessive computational time for generation of each frame of a computer animation. Thirdly, computer screens have a limited resolution and need too much computational time removing excessive detail from images generated with a higher resolution than can be displayed. Lastly, too much time is required …

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Parallel Implementation Of Vhdl Simulations On The Intel Ipsc/2 Hypercube, Ronald C. Comeau Dec 1991

Parallel Implementation Of Vhdl Simulations On The Intel Ipsc/2 Hypercube, Ronald C. Comeau

Theses and Dissertations

VHDL models are executed sequentially in current commercial simulators. As chip designs grow larger and more complex, simulations must run faster. One approach to increasing simulation speed is through parallel processors. This research transforms the behavioral and structural models created by Intermetrics' sequential VHDL simulator into models for parallel execution. The models are simulated on an Intel iPSC/2 hypercube with synchronization of the nodes being achieved by utilizing the Chandy Misra paradigm for discrete-event simulations. Three eight-bit adders, the ripple carry, the carry save, and the carry-lookahead, are each run through the parallel simulator. Simulation time is cut in at …

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An Event Driven State Based Interface For Synthetic Environments, Mark J. Gerken Dec 1991

An Event Driven State Based Interface For Synthetic Environments, Mark J. Gerken

Theses and Dissertations

Previous research at the Air Force Institute of Technology (AFIT) has produced synthetic environments using head mounted displays (HMDs) and hand measurement devices. This thesis is a continuation of AFIT synthetic environment research. Hand measurement data from a VPL DataGlove is combined with hand orientation and translational data to define a set of valid gestures. These gestures form the basis of an input language for class of finite automata known as finite state machines. Using the input symbols from this language, the user may define a finite state machine which associates a stream of input symbols with one or more …

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An Object-Oriented Database Implementation Of The Magic Vlsi Layout Design System, Timothy M. Jacobs Dec 1991

An Object-Oriented Database Implementation Of The Magic Vlsi Layout Design System, Timothy M. Jacobs

Theses and Dissertations

This thesis attempts to prove that the commercially available Object Store data management system provide the performance and functionality necessary to support a complex engineering design system. This is accomplished by modifying the Magic VLSI circuit layout design system to eliminate its current Unix file data management system and replace it with Object Store. The approach to this research effort includes a design recovery of the Magic system and identification of its ket data management functions. These functions are then modified to take advantage of the database management facilities of Object Store. Additional code is added to instrument performance measurement …

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Analysis Of A Decision Support System For Case Tool Selection And The Specification Of An Ada To Sql Abstract Interface, Tina M. Deangelis Dec 1991

Analysis Of A Decision Support System For Case Tool Selection And The Specification Of An Ada To Sql Abstract Interface, Tina M. Deangelis

Theses and Dissertations

Information overload has long been a problem in the fast moving technical field of software development. Yet quality information is needed to make informed decisions about buying software tools that help in software development. Computer Aided Software Engineering (CASE) tools help to coordinate and control information in large software developments. Many CASE tool purchases, however, are being based on ad hoc tool evaluation and selection methods which depend on biased vendor information. To capture specific knowledge about how to pick a tool for a given software development effort, a historical database that identifies important tool characteristics needed to be maintained …

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Design And Implementation Of A Graphical User Interface And Database Management System For The Saber Wargame, Andrew M. Horton Dec 1991

Design And Implementation Of A Graphical User Interface And Database Management System For The Saber Wargame, Andrew M. Horton

Theses and Dissertations

Saber is a theater level, multi-sided, airpower employment computerized wargame that can be programmed to simulate any combat scenario. The model simulates theater level combat between air and land forces, and takes into account the effects of logistics, resupply, and both theater nuclear and chemical warfare. The major objective of the Saber model is to provide a suitable educational platform to allow users to apply basic, tactical employment concepts to multiple combat units, each having a specialized mission, and incorporating every branch of the armed services. This thesis documents a graphical user interface and data management system that has been …

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An Animated Graphical Postprocessor For The Saber Wargame, Gary W. Klabunde Dec 1991

An Animated Graphical Postprocessor For The Saber Wargame, Gary W. Klabunde

Theses and Dissertations

One of the most cost effective ways to learn and home the skills necessary to conduct and win a war is through the use of realistic computer simulations of conflict, or wargames. The Saber wargame was developed for just this purpose. Saber is a multisided, theater-level simulation developed by the Air Force Institute of Technology for the Air Force Wargaming Center. It models conventional, nuclear, and chemical warfare between aggregated air and ground forces. To aid in the realism, the effects of logistics, satellites, weather, and intelligence are represented. Saber provides an avenue for senior level joint service officers to …

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Enhanced Animation Of Parallel Algorithms, Michael D. Lack Dec 1991

Enhanced Animation Of Parallel Algorithms, Michael D. Lack

Theses and Dissertations

Algorithm animation is a visualization method used to enhance understanding of the functioning of an algorithm or program. Visualization is used for many purposes, including education, algorithm research, performance analysis, and program debugging. This research, which follows from previous work, examines algorithm animation requirements for the various visualization purposes and extends the capabilities of an existing facilities, the AFIT algorithm Animation Research Facility (AAARF). The structure of AAARF is summarised and its visualization capabilities presented, analysed and compared with other similar packages. This research focuses on the parallel data requirements of the AAARF users, and the meaningful display of large …

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Graph-Based Visualization Of Formal Specification And Domain Specific Languages, Randel K. Langloss Dec 1991

Graph-Based Visualization Of Formal Specification And Domain Specific Languages, Randel K. Langloss

Theses and Dissertations

This research develops and implements Visual Refine, a graph-based visualization system, for the Refine wide-spectrum formal specification language and environment developed and marketed by Reasoning Systems, Inc. Refine specifications are represented in the Refine object base as abstract syntax trees (AST). Using these AST representations, one-to-one mappings are defined between nodes of the AST and the graphical icons of Visual Refine. Visual Refine uses these mappings to implement a set of formal transformations. Each transformation is encapsulated within a Refine rule, and this set of rules form the Visual Refine transformation system. The Visual Refine transformation system, in conjunction with …

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Plasma Transport In A Magnetic Multicusp Negative Hydrogen Ion Source, Ricky G. Jones Dec 1991

Plasma Transport In A Magnetic Multicusp Negative Hydrogen Ion Source, Ricky G. Jones

Theses and Dissertations

An analysis of plasma transport through the magnetic filter in tandem magnetic multicusp negative hydrogen ion sources was conducted to determine the mechanism of thermal electron diffusion, explain thermal electron cooling, describe the transport of primary electrons through the filter, and model positive ion species transport. The thermal electron flux was shown to exceed its classical value by one to three orders of magnitude. The flux variation with temperature was best described using a Coulomb-like temperature gradient drag term, consistent with diffusion due to ion-sound-like turbulence. Thermal electron energy flux loss was shown to be dominated by inelastic collisions at …

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Multi-Layered Feedforward Neural Networks For Image Segmentation, Gregory L. Tarr Dec 1991

Multi-Layered Feedforward Neural Networks For Image Segmentation, Gregory L. Tarr

Theses and Dissertations

Artificial neural network image segmentation techniques are examined. The biological inspired cortex transform is examined as a means to preprocess images for segmentation and classification. A generalized neural network formalism is presented as a means to produce common pattern recognition processing techniques in a single iterable element. Several feature reduction preprocessing techniques, based on feature saliency, Karhunen-Loeve transformation and identity networks are tested and compared. The generalized architecture is applied to a problem in image segmentation, a tracking of high- value fixed tactical targets. A generalized architecture for neural networks is developed based on the second order terms of the …

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A Delphi Forecast Of 1996 Roles: Air Force Institute Of Technology Information Resource Management Graduates Assigned To Base Level, David O. Block Dec 1991

A Delphi Forecast Of 1996 Roles: Air Force Institute Of Technology Information Resource Management Graduates Assigned To Base Level, David O. Block

Theses and Dissertations

Graduates of the Air Force Institute of Technology's Information Resource Management master's degree program who are subsequently assigned to base-level positions believe their IRM expertise is wasted in base administration roles that preclude the use of their up-to-date technical educations in managing automated information resources. This research forecasts the role AFIT IRM graduates assigned to base-level positions will need to fill by the year 1996. The research further determined what changes are necessary to resolve the perceived differences between current and forecast roles for these graduates. The Delphi survey method of forecasting was selected as an effective method of discovering …

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An Expert System For Measuring, Interpreting, And Managing System Performance Factors For The Work Information Management System, Billy J. C. Irwin Dec 1991

An Expert System For Measuring, Interpreting, And Managing System Performance Factors For The Work Information Management System, Billy J. C. Irwin

Theses and Dissertations

This study develops an expert system for measuring, interpreting, and managing the Wang VS operating system performance factors for the Work Information Management System. The system's performance concerns least known to system administrators are identified. Of these, SHARER buffers and VTOC cache are identified as factors that can significantly impact system performance with little effort. A six step process is used in developing the expert system. Concept maps representing the structure of the Wang VS Disk Input/Output problem domain are provided. The expert system provides information about the system parameters, SHARER buffers and VTOC cache, and recommends main memory allocations. …

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Possible Application Of Quality Function Deployment In Software Systems Development In The United States Air Force, Craig R. Lamb Dec 1991

Possible Application Of Quality Function Deployment In Software Systems Development In The United States Air Force, Craig R. Lamb

Theses and Dissertations

The objectives of the thesis were to determine whether the methods of Quality Function Deployment (QFD) could be used in the software development environment within the USAF, and whether or not this area should be researched further. The research was limited to the requirements analysis and definition phase. The different areas of study included a brief review of the structured analysis methodology, a detailed review of the QFD models currently being used in the product industries, a review of how QFD fits into the software development cycle, and specific software modifications to the QFD methodology. A review of some applications …

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Design And Application Of An Object Oriented Graphical Database Management System For Synthetic Environments, John A. Brunderman Dec 1991

Design And Application Of An Object Oriented Graphical Database Management System For Synthetic Environments, John A. Brunderman

Theses and Dissertations

The Air Force Institute of Technology (AFIT) is investigating the use of synthetic environments for military applications under the sponsorship of Rome Laboratories (RL). Areas under investigation include mission planning, battle management and flight simulation. The work reported in this thesis focuses on the object-oriented design and implementation of the Graphical Database Management System (GDMS) used to support research in these areas. GDMS provides the data structures, file format and algorithms to manage and render hierarchical, three-dimensional, polygonal models. Flexibility and adaptability were key factors in its design. A secondary objective of this research was to demonstrate the functionality of …

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