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Air Force Institute of Technology

Theses and Dissertations

1993

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Articles 1 - 30 of 103

Full-Text Articles in Engineering

An Analysis Of Fm Jamming And Noise Quality Measures, Timothy N. Taylor Dec 1993

An Analysis Of Fm Jamming And Noise Quality Measures, Timothy N. Taylor

Theses and Dissertations

This thesis provides a description of FM-by-noise jamming, both at RF and at the output of the radar receiver, in terms of spectra, time-domain waveforms, and univariate probability density of amplitude. Particular emphasis is given to the case where the peak frequency deviation of the FM modulator is sufficiently small that Woodward's Theorem does not provide a good approximation of the RF spectrum. Additionally, noise quality measures which have been used to measure noise quality of radar jammers are considered theoretically and experimentally, and it is concluded that a noise measure which incorporates both a spectral measure and a probability …

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Creation Of Prototype Aircrew Protection Equipment Based On Face Anthropometry, Martin E. Piccus, Gary A. Smith, Brian K. Standley, Tami L. Volk, Linda B. Wildes Dec 1993

Creation Of Prototype Aircrew Protection Equipment Based On Face Anthropometry, Martin E. Piccus, Gary A. Smith, Brian K. Standley, Tami L. Volk, Linda B. Wildes

Theses and Dissertations

The objective of this research is to develop a process which will analyze and group human faces, concentrating on the oxygen mask seal area, into a minimum number of generic yet distinct face types. The shape and size, or form, of the face is described by bending energies. This bending energy provides the features for the grouping of similar face types, while distinguishing representatives for each cluster. The face tariffs are the percentage of faces grouped under a representative face. The representative faces are then transformed Into three-dimensional solids using computer-aided design. A rapid prototype creates the solids or plugs …

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Filtering, Coding, And Compression With Malvar Wavelets, Stephen R. Hall Dec 1993

Filtering, Coding, And Compression With Malvar Wavelets, Stephen R. Hall

Theses and Dissertations

This thesis develops and evaluates a number of new concepts and tools for the analysis of signals using Malvar wavelets lapped orthogonal transforms . Windowing, often employed as a spectral estimation technique, can result in irreparable distortions in the transformed signal. By utilizing the Malvar wavelet, any signal distortion resulting from the transformation can be eliminated or cancelled during reconstruction. This is accomplished by placing conditions on the window and the basis function and then incorporating the window into the orthonormal representation. Paradigms for both a complex-valued and a real-valued Malvar wavelet are summarized. I-lie algorithms for the wavelets were …

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A Methodology To Assess The Impact Of The Global Positioning System On Air Combat Outcomes, Stephen F. Sovaiko Dec 1993

A Methodology To Assess The Impact Of The Global Positioning System On Air Combat Outcomes, Stephen F. Sovaiko

Theses and Dissertations

The Air Force has a requirement to quantify the force enhancement effects of military space systems, but no methodology currently exists for the measurement of their contribution to air combat outcome. This research examines the Global Positioning System GPS and models its influence on air-to-ground combat. The decision analysis technique of influence diagrams is used to identify the effects of GPS launch decisions and constellation size on the navigation accuracy available to air combatants. The effect of accuracy variations on combat outcome is shown by using a value tree to identify the affected campaign Measures of Effectiveness. The study reveals …

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Guidelines For Ensuring Software Supportability In Systems Developed Under The Integrated Weapon System Management Concept, Forrest F. Butts Iii, Anthony C. Johndro Dec 1993

Guidelines For Ensuring Software Supportability In Systems Developed Under The Integrated Weapon System Management Concept, Forrest F. Butts Iii, Anthony C. Johndro

Theses and Dissertations

This thesis studied the software maintenance planning and practices of the pilot Integrated Weapon System Management IWSM programs. Before IWSM, a System Program Office SPO acquired an Air Force weapon system then passed it to an Air Logistics Center ALC for follow-on support. The ALC was forced to maintain the software despite its questionable maintainability. The SPO de- emphasized maintainability because maintenance was an ALC responsibility and building maintainable software increased development costs and lengthened schedules. The IWSM philosophy closes the gap between development and maintenance. A System Program Director SPD, who oversees both system development and maintenance, has an …

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Demonstration Of Improved Software Support Labor Estimation For Air Force Operational Flight Programs Through Functional Orientation, Ronald R. Warner Jr., Darrel L. Wright Dec 1993

Demonstration Of Improved Software Support Labor Estimation For Air Force Operational Flight Programs Through Functional Orientation, Ronald R. Warner Jr., Darrel L. Wright

Theses and Dissertations

This study demonstrated two approaches to improve current software support effort estimation models for aircraft software. Both approaches involved a functional orientation not used by existing models. The first approach demonstrated how to orient a model to reflect the block change cycle modification process and how to represent support effort changes over time in order to improve effort estimation accuracy. Current software models do not reflect the support environment or the temporal characteristics of aircraft software support. The second approach demonstrated how to calibrate a model by properly selecting source data in order to increase accuracy. Support calibration is not …

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Design And Construction Of The Aerobot Robotic Manipulator (Arm), William L. Cochran Dec 1993

Design And Construction Of The Aerobot Robotic Manipulator (Arm), William L. Cochran

Theses and Dissertations

This thesis designed, constructed, and tested a robotic arm for the Aerobot Aerial Robot. The main purpose of the ARM is to enable the Aerobot to retrieve objects for use in an annual robotics competition. Design of the ARM involved synthesizing the characteristics of simplicity, weight, strength, and size. The result was a three-degree-of-freedom manipulator that uses electric motors, cable linkages, and telescoping tubes to access a work space below the Aerobot. Forward and inverse kinematics were investigated to enable automation of the ARM. Data was collected from infrared sensors to validate the model. Manipulation of the ARM is presently …

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Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gregory J. Schiller Dec 1993

Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gregory J. Schiller

Theses and Dissertations

The purpose of this thesis is to apply moving-bank multiple model adaptive estimation and control MMAEMMAC algorithms to an actual space structure SPICE being examined at Phillips Laboratory at Kirtland AFB, NM. The structure consists of a large platform and a smaller platform connected by three legs in a tripod fashion. Kalman filtering and LQG control techniques are utilized as the primary design tool. Implementing a bank of filters increases the robustness of the LQG controller when uncertainties exist in the system model, whereas the moving bank is utilized to reduce the computational load. Several reduced-order models are developed from …

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Development And Implementation Of A Scramjet Cycle Analysis Code With A Finite-Rate-Chemistry Combustion Model For Use On A Personal Computer, Clarence F. Chenault Dec 1993

Development And Implementation Of A Scramjet Cycle Analysis Code With A Finite-Rate-Chemistry Combustion Model For Use On A Personal Computer, Clarence F. Chenault

Theses and Dissertations

This study compared the performance of an equilibrium combustion model to a finite-rate-chemistry combustion model for a fixed geometry Scramjet flying at the flight conditions of Mach 12, 15, and 18 with a constant dynamic pressure of 50,000 Pa. An integrated PC-based code, developed specifically for this study, models the combustor as an equilibrium combustion process or as finite-rate-chemistry combustion process. This integrated program is based on two existing programs, Ramjet Performance Analysis (RJPA) and 3 STREAM. The effects of mixing schedule, combustor length, and combustor exit area were investigated. The results of this study indicate that inefficient mixing is …

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Influence Of Embedded Optical Fibers On Compressive Strength Of Advanced Composites, Stefan B. Dosedel Dec 1993

Influence Of Embedded Optical Fibers On Compressive Strength Of Advanced Composites, Stefan B. Dosedel

Theses and Dissertations

This study investigated the effects of embedding optical fibers into advanced composite materials. This combination was meant to simulate 'smart structures' that have been shown to sense several different variables in the composite including strain, temperature, and damage. A laminate orientation taken from an existing aircraft structure was used to fabricate sixteen groups of specimens which were subjected to compression testing in an IITRI fixture to determine the ultimate compressive strength and modulus of elasticity. Ten of these groups were fabricated with optical fibers while the other six were control groups and contained no optical fibers. This study showed that …

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Investigation Of Compressive Behavior For Metal Matrix Composites With A Circular Hole, Janet L. Gooder Dec 1993

Investigation Of Compressive Behavior For Metal Matrix Composites With A Circular Hole, Janet L. Gooder

Theses and Dissertations

This study investigated the notched and unnotched macromechanical response due to micromechanical behavior of [0/±45/90]S SCS-6/β 21 S and [0/90] 2S Sigma/β 21S subjected to static compressive loads at room temperature. The stress-strain behavior and mechanical response in the presence of a circular hole was examined. A clear description of the progressive nature of damage, which ultimately resulted in failure, was provided. The effect of elevated temperature was shown for SCS-6/β 21S. The ultimate compressive strength and elastic modulus were reported for both MMCs. Sigma/β 21S and SCS-6/β 21S were mildly notch sensitive at room temperature. Notch sensitivity of …

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Virtual Memory Management And Virtual Bus Overloading On Multiple Channel Architectures, John N. Armitstead Dec 1993

Virtual Memory Management And Virtual Bus Overloading On Multiple Channel Architectures, John N. Armitstead

Theses and Dissertations

Today's computational environment requires the processing capabilities available only through parallel architectures. The bottleneck that limits the potential of parallel processing is communication between processors, memories, and other hardware devices. A proposed multiple channel architecture (MCA) utilizes tunable semiconductor lasers and fiber optic cables that serve as the communication medium between processor, memory, and I/O nodes. A memory management unit (MMU) was completely described and implemented in a multiprocessor simulator. A permutation-based interleaving (PBI) scheme was utilized to reduce the chance of memory access collisions. Virtual bus utilization, number of collisions, and message traffic patterns were studied under various amounts …

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Design Of A Parallel Discrete Event Simulation Coprocessor, Jacob L. Berlin Dec 1993

Design Of A Parallel Discrete Event Simulation Coprocessor, Jacob L. Berlin

Theses and Dissertations

A Parallel Discrete Event Simulation Coprocessor was designed to off- load the synchronization overhead from the processors executing the application. In a multiprocessor architecture, one coprocessor executes the synchronization routines for each host processor. Speedup can be achieved when the host processor executes the application and the coprocessor concurrently executes synchronization routines. The coprocessor uses a programmable microcode control store to guarantee flexibility in the synchronization routines. The coprocessor uses an Extreme Search Associative Memory to support fast Next Event Queue NEQ management. This associative memory uses bit-serial word-parallel search logic to provide 01 insert and retrieval time of events …

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Weapon System Sensor Integration For A Dis-Compatible Virtual Cockpit, Matthew N. Erichsen Dec 1993

Weapon System Sensor Integration For A Dis-Compatible Virtual Cockpit, Matthew N. Erichsen

Theses and Dissertations

This thesis continues the Virtual Cockpit VC research which investigates distributed interactive virtual flying, environments. The VC vl.0 used the SIMNET protocols to only communicate position and orientation over a common network. A simple cockpit instrumentation configuration and limited head- tip display, HUD showed aircraft state. With VC vl.0 weapons or sensors could not interact in the simulation environment. The VC v2.0 transitions from the SIMNET protocol to a partial implementation of the Distributed Interactive Simulation DIS v2.0.3 protocol. Simulated radar and forward looking infra-red FLIR sensors were developed to aid operator detection and designation when employing various munition types. …

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Integration And Enhancement Of The Saber Wargame, Karl S. Mathias Dec 1993

Integration And Enhancement Of The Saber Wargame, Karl S. Mathias

Theses and Dissertations

The Saber wargame is a theater-level air/land battle wargame written in Ada that is being developed for the Air Force Wargaming Center at Maxwell AFB, AL. This thesis documents how the user interface and simulation engine were integrated. Integration was accomplished by developing a portable object-oriented database system (OODBMS) interface. The interface was implemented in Ada and tied to an OODBMS also written in Ada. Using the interface, both subsystems were able to work from a consistent database and exchange information. The user interface was enhanced by converting it from the Software Technology for Adaptable Reliable Systems Ada/X Window System …

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Human Visual System Enhancement Of Reconstructed Satellite Images, James E. Treleaven Dec 1993

Human Visual System Enhancement Of Reconstructed Satellite Images, James E. Treleaven

Theses and Dissertations

This research investigated the enhancement of satellite images. The goal was to develop and test a suite of image enhancement software routines to improve the quality of reconstructed images for the human visual system. The primary focus was to enhance satellite features. Enhancement was accomplished in both the spatial domain and the frequency domain. In the spatial domain, routines were developed to enhance image contrast and edges. In the frequency domain, a routine was developed using research into the human visual system. The transfer function of the human visual system was used to develop a filter for frequency domain enhancement. …

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Analysis Of The Effects Of Wake Passage On Heat Transfer In A Linear Turbine Cascade, Kevin S. Allen Dec 1993

Analysis Of The Effects Of Wake Passage On Heat Transfer In A Linear Turbine Cascade, Kevin S. Allen

Theses and Dissertations

This study investigated the effect of wake passage on the heat transfer in a linear turbine cascade. The apparatus used was the Air-Force Institute of Technology linear Turbine Cascade Test Facility (TCTF). The TCTF was fitted with a be Pulley system to facilitate a series of translating bars. The bars, when passed d upstream of the cascade, created a series of wakes. The parameters varied were freestream model Reynolds number and bar conditions, i.e. , bars in, bars out, and bar passing frequency. One blade in the TCTF was instrumented to allow pressure and temperature measurements at discrete points on …

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The Effect Of Cutout Dimensionality On The Collapse Characteristics Of Cylindrical Composite Shells Of Varying Thickness, John C. Del Barga Dec 1993

The Effect Of Cutout Dimensionality On The Collapse Characteristics Of Cylindrical Composite Shells Of Varying Thickness, John C. Del Barga

Theses and Dissertations

This study involved a numerical and experimental investigation of the (geometric instability of graphite/epoxy cylindrical panels with free vertical edges undergoing axial compression. Symmetric quasi-isotropic laminates with five different size centralized cutouts, were investigated for two axial lengths of panels and three thicknesses. The study compared experimental data to results from SHELL, a geometrically nonlinear finite-element program which incorporates a parabolic transverse shear strain distribution through the thickness. The research verified that the SHELL program will provide good predictions of the collapse characteristics of a panel with large cutouts of varying dimensions undergoing large displacements and rotations. The best correlation …

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A Study Of Two Dimensional Tapered Periodic Edge Treatments To Reduce Wideband Edge Diffraction, Russell A. Burleson Dec 1993

A Study Of Two Dimensional Tapered Periodic Edge Treatments To Reduce Wideband Edge Diffraction, Russell A. Burleson

Theses and Dissertations

This is a brief summary of a study to reduce diffraction from an infinite two dimensional edge using tapered periodic surfaces. The concept is to use the impedance characteristics of a periodic surface to create a tapered impedance much like a tapered resistance commonly used for diffraction reduction. This approach has several advantages over. tapered resistive treatments to include ease of fabrication, better engineering control of the impedance and negligible loss absorbed by the ta per. In this study, four periodic tapers were design, built and tested. These tapers were also modeled using a variety of numerical techniques. The results …

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Analysis And Simulation Of A Gps Receiver Design Using Combined Delay-Lock And Modified Tanlock Loops, George D. Harris Dec 1993

Analysis And Simulation Of A Gps Receiver Design Using Combined Delay-Lock And Modified Tanlock Loops, George D. Harris

Theses and Dissertations

The purpose of this thesis was to investigate the performance of two types of tracking loops used in Global Positioning System (GPS) receivers. The first loop, the Delay-Lock Loop (DLL), is responsible for maintaining synchronization with the received PN sequence. The second loop, the Modified Tanlock Loop (MTLL), is responsible for maintaining synchronization with the carrier signal. The performance of the two loops is investigated first separately then their performance is evaluated when operated together. This thesis is an investigation on the ability of these two loops to overcome corruption of the input signal due to noise. Expanding the dynamic …

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Development Of A Performance Evaluation Tool (Mmsofe) For Detection Of Failures With Multiple Model Adaptive Estimation (Mmae), Robert L. Nielsen Dec 1993

Development Of A Performance Evaluation Tool (Mmsofe) For Detection Of Failures With Multiple Model Adaptive Estimation (Mmae), Robert L. Nielsen

Theses and Dissertations

Multiple model Kalman Filter (KF) techniques are used extensively for Multiple Model Adaptive Estimation (MMAE), Multiple Model Adaptive Control (MMAC), and Distributed Kalman Filter (DKF) applications to determine Bayesian- blended optimal estimates of states, uncertain parameters, and optimal control signals. Multiple model methods are used for sensor management, Failure Detection and Isolation (FDI), and other Guidance and Control (G and C) applications. A simulation tool called the Multiple Model Simulation for Optimal Filter Evaluation (MMSOFE) has been in this research. MMSOFE is based on the well-benchmarked single Kalman filter tool called Multimode Simulation for Optimal Filter Evaluation (MSOFE). MMSOFE is …

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A Virtual Environment For Satellite Modeling And Orbital Analysis In A Distributed Interactive Simulation, Andrea A. Kunz Dec 1993

A Virtual Environment For Satellite Modeling And Orbital Analysis In A Distributed Interactive Simulation, Andrea A. Kunz

Theses and Dissertations

In response to the need for a more realistic, interactive, and immersive space simulation system, the Joint National Intelligence Defense Staff JNIDS has sponsored the development of the Satellite Modeler at the Air Force Institute of Technology AFIT. The Satellite Modeler SM is a virtual environment VE application that allows analyst-users to enter a virtual near- Earth space environment and visualize realistic satellite models performing accurate orbital motion. The Satellite Modeler provides manipulation functions that allow a user to interact with multiple satellite models and satellite constellations. The system affords the user multiple vantage points within the environment to view …

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Satellite Attitude Determination Using Linear Combination Of Models, Martin S. Chin Dec 1993

Satellite Attitude Determination Using Linear Combination Of Models, Martin S. Chin

Theses and Dissertations

In satellite analysis, it is often necessary to determine the attitude of a satellite from a two dimensional image of the satellite. This thesis describes work performed to determine the attitude of a satellite relative to a reference position. The attitude is described in terms of the scaling, rotation and translation of the reference that will result in a pose that can be projected to form the image of interest. The techniques used are based on finding coefficients for the linear combination of basis images and decomposition of a composite transformation matrix. The methods were initially modeled in Mathematica and …

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Radar Cross Section Visualization Using Sample Buffer Progressive Refinement Volume Rendering, Alain L. Jones Dec 1993

Radar Cross Section Visualization Using Sample Buffer Progressive Refinement Volume Rendering, Alain L. Jones

Theses and Dissertations

This study developed a prototype for an interactive radar cross section visualization software system. The system, hosted on a Silicon Graphics workstation, is intended to support aircrews, mission planners, aircraft designers, and others who require an understanding of aircraft radar cross section characteristics. The input to the system is a set of radar cross section samples taken at various aspect angles. A pre-processor developed as part of this study transforms the input radar cross section data into a three-dimensional cuberille data volume. This data volume is then visualized using an interactive volume renderer. The interactive volume renderer implements progressive image …

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Evaluation Of Moderate Angle Of Attack Roll Of A Dual Engine, Thrust Vectoring Aircraft Using Quantitative Feedback Theory, Kevin E. Boyum Dec 1993

Evaluation Of Moderate Angle Of Attack Roll Of A Dual Engine, Thrust Vectoring Aircraft Using Quantitative Feedback Theory, Kevin E. Boyum

Theses and Dissertations

This thesis develops an innovative approach to the design of a flight control system for performing the large-amplitude velocity vector roll maneuver at high angles of attack AOAs. A six degree of freedom aircraft model is developed from the fundamental nine-state equations of motion using a modified linearization technique. The MIMO multiple-input multiple-output Quantitative Feedback Theory QFT robust control design technique is then used to jointly address the system nonlinearities present in this maneuver and the changes in the system parameters due to changes in flight condition, treating them as structured uncertainty in the design of a three-axis rate-commanded control …

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Incorporation Of Carrier Phase Global Positioning System Measurements Into The Navigation Reference System For Improved Performance, Neil P. Hansen Dec 1993

Incorporation Of Carrier Phase Global Positioning System Measurements Into The Navigation Reference System For Improved Performance, Neil P. Hansen

Theses and Dissertations

In order to quantify the performance and accuracy of existing navigation systems, the U.S. Air Force has been using the Completely Integrated Reference Instrumentation System (CIRIS) as a baseline. CIRIS combines information from an inertial navigation unit, a barometric altimeter, and a range/range-rate system of ground transponders to obtain a navigation solution. This research explores the possibilities of enhancing CIRIS by adding measurements obtained from the Global Position System (GPS). Pure pseudorange measurement updates to the CIRIS Extended Kalman Filter form the basis of the Navigation Reference System (NRS). Applying differential corrections to the pseudorange measurements forms the basis of …

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Development Of A 4-Bit Parallel Analog-To-Digital Converter And A Four- Quadrant Double-Balanced Mixer Using Heterojunction Bipolar Transistor Technology, Scott F. Jokerst Dec 1993

Development Of A 4-Bit Parallel Analog-To-Digital Converter And A Four- Quadrant Double-Balanced Mixer Using Heterojunction Bipolar Transistor Technology, Scott F. Jokerst

Theses and Dissertations

A 4-bit parallel analog-to-digital converter (ADC) and a four- quadrant double-balanced mixer were designed and simulated using heterojunction bipolar transistor (HBT) technology to test the dc and high-frequency characteristics of HBTs. HSPICE simulations of small-scale components and the large-scale ADC operated within expected ranges. The ADC implemented with the Rockwell HBT model operated at a sampling rate of over 1 GHz, and the Fellows model also operated at a 1 GHz sampling rate. The mixer produced an intermediate frequency (IF) signal using radio frequency (RF) and local oscillator (LO) inputs. The circuit produced a +9 dB power gain with less …

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Analyzing Adaptive Beamformer Performance In A Stable Multipath Environment, Mark Godino Dec 1993

Analyzing Adaptive Beamformer Performance In A Stable Multipath Environment, Mark Godino

Theses and Dissertations

Fighter aircraft equipped with X-Band radars having an adaptive beamforming capability exhibit degraded performance due to radome multipath reflection (RMR). The reflections from the radome into the antenna array degrade the pattern and cause the formation of large sidelobes. This phenomenon makes detection of LO targets difficult when jamming enters the high RMR sidelobes. Actual radomes are curved and cause reflected wavefronts to be nonplanar. Analyzing beamformer performance under these conditions is difficult, since the beamformer response is defined as the amplitude and phase change experienced by a complex plane wave as a function of frequency and location. To work …

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Design Of A Flight Controller For An Unmanned Research Vehicle With Control Surface Failures Using Quantitative Feedback Theory, Mark S. Keating Dec 1993

Design Of A Flight Controller For An Unmanned Research Vehicle With Control Surface Failures Using Quantitative Feedback Theory, Mark S. Keating

Theses and Dissertations

This thesis describes the application of the multiple-input multiple- output (MIMO) Quantitative Feedback Theory (QFT) design technique to the design of a digital flight control system for the Lambda Unmanned Research Vehicle (URV). The QFT technique allows the synthesis of a control system which is robust in the presence of structured plant uncertainties. Uncertainties considered in this design are the aircraft's plant variation within the flight envelope and the effects of damage to aircraft control surfaces. Mathematical models of control surface failure effects on aircraft dynamics are derived and used to modify an existing small perturbation model of the Lambda. …

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The Afit Multielectrode Array For Neural Recording And Simulation: Design, Testing, And Encapsulation, James R. Reid Jr Dec 1993

The Afit Multielectrode Array For Neural Recording And Simulation: Design, Testing, And Encapsulation, James R. Reid Jr

Theses and Dissertations

A two-dimensional, X-Y addressable, multiplexed array of 256 electrodes (16 x 16) has been fabricated using conventional semiconductor processing techniques. The individual electrodes are 16O microns x 160 microns, approximating the size of the cortical columns; the overall array size is 3910 microns x 3910 microns. The array has been fitted to a chronically implantable package and tested for several days in a simulated neural environment. EEG-like data were collected successfully from individual electrodes in the array. This array improves on a previous design of a 16 electrode (4 x 4) array that was chronically implanted on the cortex of …

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