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Air Force Institute of Technology

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Articles 1321 - 1328 of 1328

Full-Text Articles in Electrical and Computer Engineering

Model-Based Reasoning In Electronic Repair, Kenneth B. Cohen Dec 1990

Model-Based Reasoning In Electronic Repair, Kenneth B. Cohen

Theses and Dissertations

Diagnosis is the process of identifying the cause for an observed behavior of a system. Model-based reasoning uses knowledge of the behavior of the component and the interconnection of the components to diagnose a system. This thesis investigates the application of model-based reasoning to the problem of isolating faulty components of an analog electronic circuit. More specifically, this thesis describes an architecture for a model-based diagnostic system for electronic modules, implements an assumption-based truth maintenance system (one of the component parts of a model-based diagnostic system), and creates the interface between the truth maintenance system and the diagnostic system.

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A Study Of The Effects Of Noise Jamming On Radar Receivers, Paul E. Bishop Dec 1990

A Study Of The Effects Of Noise Jamming On Radar Receivers, Paul E. Bishop

Theses and Dissertations

A comprehensive study of the effects of noise jamming on various pulsed radar receiver types is proposed. First, a literature review on the sources of electrical noise and various jamming waveforms is presented. The power spectra for three noise jamming waveforms are rigorously derived. These cases are shot noise in a parallel-plate diode, a series of pulses with random amplitudes and intervals, and for a series of pulses with random amplitudes, spacing and phases. Next, the probability density functions for the output of linear and quadratic detectors are developed. For each detector type, the probability density functions for the cases …

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Fractal Geometry Segmentation Of High Resolution Polarimetric Synthetic Aperture Radar Data, Joseph L. Brickey Dec 1990

Fractal Geometry Segmentation Of High Resolution Polarimetric Synthetic Aperture Radar Data, Joseph L. Brickey

Theses and Dissertations

This thesis investigated the potential of fractal dimension estimation for segmenting high resolution polarimetric synthetic aperture radar. The data used during this research were collected with the Advanced Detection Technology Sensor (ADTS) developed by Massachusetts Institute of Technology Lincoln Laboratory with Defense Advanced Research Projects Agency funding. ADTS is a fully polarimetric calibrated 35 GHz SAR with one foot impulse response. A method of applying the correlation dimension algorithm developed by Grassberger and Procaccia for estimating the dimension of time series data was implemented to estimate the correlation dimension of polarimetric SAR data. A threshold sensitivity study was performed to …

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Interference Cancellation In Rf Signals Using Adaptive Array Techniques, Mark E. Brown Dec 1990

Interference Cancellation In Rf Signals Using Adaptive Array Techniques, Mark E. Brown

Theses and Dissertations

This study investigated the effectiveness of the Least Means Squared (LMS) algorithm against various types of common jammers. The LMS algorithm was implemented using the Block Oriented Systems Simulator (BOSS). The LMS algorithm was inserted at the output of a two element antenna array. The array was configured so as to have one-half wavelength spacing. A quadrature hybrid signal structure was used. The array was then tested against a barrage and sweep jammer. The barrage jammer testing consisted of varying each of the three available jammer parameters; power, frequency and angle of arrival individually. The sweep jammer testing consisted of …

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Synthetic Aperture Multi-Telescope Tracker Apparatus, Richard A. Carreras, Salvatore J. Cusumano, Morton B. Jenks, Robert I. Suizu May 1987

Synthetic Aperture Multi-Telescope Tracker Apparatus, Richard A. Carreras, Salvatore J. Cusumano, Morton B. Jenks, Robert I. Suizu

AFIT Patents

A plurality of telescopes provide output return signals which are applied both directly and in sampled form to a photo-detector cell. The detected signals from the photo-detector will represent the constant and transient errors of the telescope system. A low pass filter insures that the tracker provides only the constant or D.C. component of the error, while a high pass filter insures that the existing measuring devices for each telescope beam provide only the transient or A.C. component of the error. The A.C. and D.C. error signals are summed together with the appropriate applied gains on each channel such that …

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Optically Phased Laser Transmitter, Janet S. Fender, Salvatore J. Cusumano, Robert R. Butts, Christopher R. Dehainaut Jan 1987

Optically Phased Laser Transmitter, Janet S. Fender, Salvatore J. Cusumano, Robert R. Butts, Christopher R. Dehainaut

AFIT Patents

An apparatus and technique are described for phasing the outputs of a multiplier telescope array used as a laser transmitter. The technique uses samples of the transmitted beams to control optical path lengths through the separate telescopes so that the beams add coherently at the receiver. The phasing concept is applicable both to systems which provide inputs to the multiple telescopes by dividing a single laser beam and to systems in which the inputs to the telescopes and multiple, phase-locked laser beams. The approach is also compatible with single line and multi-line lasers, and it does not entail stringent alignment …

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High Discharge Rate Characteristics Of Nickel-Cadmium Batteries For Pulse Load Filtering, Gregory M. Gearing, Michael B. Cimino, David H. Fritts, John F. Leonard, Anthony J. Terzuoli Jr. Jul 1985

High Discharge Rate Characteristics Of Nickel-Cadmium Batteries For Pulse Load Filtering, Gregory M. Gearing, Michael B. Cimino, David H. Fritts, John F. Leonard, Anthony J. Terzuoli Jr.

Faculty Publications

Several tests of specially fabricated nickel-cadmium batteries having circular disk type electrodes were considered. These batteries were evaluated as filter elements between a constant current power supply and a five hertz pulsed load demanding approximately twice the power supply current during the load on portion of the cycle. Short tests lasting 10,000 cycles were conducted at up to a 21 C rate and an equivalent energy density of over 40 Joules per pound. In addition, two batteries were subjected to 107 charge/discharge cycles, one at a 6.5 C rate and the other at a 13 C rate. Assuming an …

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Study Of Longitudinal Landing Flying Qualities Evaluation Using Pilot Model Theory, Eric D. Didomenico Dec 1984

Study Of Longitudinal Landing Flying Qualities Evaluation Using Pilot Model Theory, Eric D. Didomenico

Theses and Dissertations

Control Anticipation Parameter (CAP), used in MIL-SPEC-8785C as a longitudinal handling qualities criterion does not adequately distinguish between different flight phases. Recent flight test data from the Landing Approach Higher Order Systems (LAHOS) study further indicate the inadequacy of the second order approximations for higher order longitudinal landing flying qualities. Nine Aircraft that fall within the Level 1 boundary reveal pilot ratings ranging from 1.5 to 10 (Cooper/Harper). These nine aircraft are studied by combining their longitudinal dynamics with pilot modelling to examine a better method of landing flying quality prediction and evaluation. Pilot model theory (cross-over pilot model) is …

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