Engineering Commons^™

Kalman Filter Tracking Of A Reflective Target Using Forward Looking Infrared Measurements And Laser Illumination, Roger J. Evans

Theses and Dissertations

This thesis investigates Kalman filter tracking of a missile hardbody, at a range of 2,000 kilometers, using forward looking infrared (FLIR) measurements and low-energy laser illumination of the missile hardbody. A missile reflectivity model provides realism in the simulation. The tracking scenario uses one filter, provided with FLIR measurements, to estimate the intensity centroid location of the missile's plume. A second, independent, filter estimates the center-of-mass of the missile hardbody. The center-of-mass measurements provided to this filter are computed from information gathered by scanning a low-energy laser along the first filter's estimate of the missile velocity vector. Single scans of …

Electromagnetic Scattering From Impedance Strips And Impedance-Loaded Conducting Strips, Mark C. Heaton

Theses and Dissertations

This paper investigates the scattering from impedance strips and impedance-loaded conducting strips. The UTd diffraction coefficient for an edge in a conductor is heuristically modified for impedance edges and junctions. Essentially, this is done by scaling the UTD diffraction coefficients according to changes in the geometrical optics field. The new diffraction coefficients are then used to investigate the scattering from impedance strips and impedance- loaded conducting strips. Both uniform and tapered impedances are considered. Results are compared to moment method and physical optics predictions and to measured data. The scattering pattern of a uniform impedance strip was seen to behave …

A Method Of Moments Solution For The Electric Currents On An Aperture-Fed, Stacked Patch Microstrip Antenna, William L. Irvin

Theses and Dissertations

This study presents a method of moments solution for the surface currents and charge distributions on an aperture-fed, stacked patch antenna. To make the solution independent of the antenna excitation technique, an aperture magnetic current distribution is assumed, and the spatial Green's functions of the antenna are used to calculate the tangential fields on the antenna patches and coefficients for a finite series expression of the surface currents and charge densities. The Green's functions of the antenna are modeled with polynomials that are a function of the radial distance separating observer and source locations. The method of moments solution is …

Design And Fabrication Of An Implantable Cortical Semiconductor Integrated Circuit Electrode Array, Pierre K. Lefevre

Theses and Dissertations

This research furthered the processing steps of the AFIT 16 by 16 implantable cortical semiconductor integrated circuit electrode array, or brain chip. The areas of interest include the brain chip electron ics, metallization, ionic permeation, and implantation. The electronics and metallization are heavily covered. A high speed, single clock divide-by-two circuit was modified with a reset transistor and cascaded to form a ripple counter. This device had stable operation at specific source voltage and clock voltage and frequency. A 7-stage inverter with 10 unmodified divide-by-two circuits cascaded operated between 1.7 and 8 volts, and between 39 Khz and 1 Mhz, …

Analysis And Testing Of A Bistatic Radar Cross Section Measurement Capability For The Afit Anechoic Chamber, Timothy D. Mccool

Theses and Dissertations

This research effort examined the feasibility of performing bistatic radar cross section (RCS) measurements in the AFIT anechoic chamber. The capability was established to measure the bistatic RCS of a target versus frequency and versus target azimuth angle. In either case, one of three bistatic angles (angle between transmit and receive antennas) is available: 45 degrees, 90 degrees, and 135 degrees. Accurate bistatic RCS measurements were obtained using a CW radar and utilizing background subtraction, bistatic calibration, and software range gating. Simple targets were selected for validation purposes since their bistatic RCS could be predicted. These consisted of spheres and …

Rule-Based Frequency Domain Speech Coding, Vance M. Mcmillan

Theses and Dissertations

A speech processing system is designed to simulate the transmission of speech signals using a speech coding scheme. The transmitter portion of the simulation extracts a minimized set of frequencies in Fourier space which represents the essence of each of the speech timeslices. These parameters are then adaptively quantized and transmitted to a receiver portion of the coding scheme. The receiver then generates an estimate of the original timeslice from the transmitted parameters using a sinusoidal speech model. After initial design, the thesis investigates how each of the design parameters affect the human perceived quality of speech. This is done …

Analysis Of Visual Illusions Using Gabor Filters, Richard A. Oberndorf

Theses and Dissertations

This thesis has demonstrated the correctness of using spatial filters in the analysis of various visual illusions; the specific form of filter has been derived from a Gabor equation model of simple cell response on the visual cortex. The Gabor Low Pass Filter (GLPF) applied to these anomalies was derived from proposals made that simple cell response on the visual cortex may be modeled by a set of equations originally proposed by Gabor in the 1940's. Based upon the extension of these equations into two dimensions, a GLPF process was applied to computer-generated black and white illusions (the Kanizsa Triangle, …

Quantization Noise Characteristics Resulting From Gaussian, Negative- Exponential, And Sinusoidal Random Input Signals, Van N. Osborne

Theses and Dissertations

The purpose of this study was to investigate the trade-off between the number of quantization levels and the resulting noise characteristics for three classes of commonly occurring input signals, namely, those signals possessing Gaussian, negative-exponential and random sinusoidal distributions. This study derived expressions for the mean-squared error, output spectrum and error spectrum by expanding the nonlinear quantization function into a summation of orthogonal polynomials matched to the corresponding input signal distribution. Once accomplished, orthogonality properties were applied to provide usable expressions. A set of three Fortran 77 programs were developed- each of which applied to one of the studied input …

Pulsed Compression For Aerosol Ranging With Coherent Pulse-Doppler Lidar Systems, Jerry L. Rogers

Theses and Dissertations

This thesis provides a thorough review of conventional matched filter radar theory as it applies to aerosol sensing lidar. Basic matched-filter radar theory and the complex, dense aerosol target model eventually lead to a general derivation of the matched-filter radar receiver response to a dense aerosol target environment. The matched-filter response is obtained in terms of a two dimensional convolution of the target scattering function and the radar ambiguity function. The range and radial velocity resolution of various radar signals were compared using the matched-filter radar receiver and scattering function models. Pulse compression radar signals were compared to the simple …

Automatic Flight Control System Design For An Unmanned Research Vehicle Using Discrete Quantitative Feedback Theory, David G. Wheaton

Theses and Dissertations

This thesis presents the application of non-minimum phase (NMP) w'- plane discrete MIMO (multiple-input-multiple-output) Quantitative Feedback Theory (QFT) to the design of a three-axis rate-commanded automatic flight control system for an unmanned research vehicle (URV). The URV model used has seven inputs and three outputs derived from the small-angle perturbation equations of motion. Plant parameter uncertainty consists of six flight conditions derived from variations in the aircraft center of gravity, airspeed, and gross weight. A weighting matrix delts is used to post-multiply the plants for blending the seven effector inputs into three effective rate-command inputs and resulting in an effective …

An Evaluation Of An Ada Implementation Of The Rete Algorithm For Embedded Flight Processors, F. Jesse Fanning

Theses and Dissertations

The purpose of this thesis was to design and develop an expert system shell in Ada, and to evaluate the shell's execution and size performance to determine its suitability for real-time operation on the MIL-STD-1750A embedded flight processor. The expert system shell uses the CLIPS/Ada inference engine, a forward-chaining Ada implementation of Rete. The expert system shell design is presented along with an overview of the target environment--the MIL-STD-1750A VHSIC Avionic Modular Processor (VAMP) running under the Ada Avionics Real-Time Software (AARTS) Operating System. Theoretical and empirical complexity analyses of the inference engine are presented and discussed in view of …

Fluorescent Lifetime Measurements Of Rare Earth Elements In Gallium Arsenide, Danny J. Topp

Theses and Dissertations

Lifetime measurements of the excited states of three GaAs semiconductors doped with the rare earth elements Erbium (ER), Praseodymium (Pr) , and Thulium (Tm) has been studied using a pulsed nitrogen laser and germanium detector. The measurements were made with an experimental set up with a system response time of 0.34 micro seconds. A 330 milliwatt nitrogen laser with a wavelength of 3370 angstrums was used to excite transitions of the rare earth elements.

Multidisciplinary Modeling And Design Of A Space Structure, Brian K. Cassiday, Lawrence L. Gatchet, John T. Tester, Stephen O. Gaines Ii, Mario N. Moya

Theses and Dissertations

A method is needed to simultaneously integrate several engineering disciplines into one complete model to determine the performance of the system as a whole during the design development. System engineering methodologies are particularly suited to this problem. These methods provide a structured approach to problem formulation and system parameter identification. Bond graphs are also well suited as bond graphs model power flow and energy relationships within subsystems, a characteristic inherent to all dynamic systems. The intent of this research was to demonstrate the use of concurrent engineering theory to systematically model a large flexible space structure involving several engineering disciplines. …

Model-Based Reasoning In The Detection Of Satellite Anomalies, Ralph W. Dries

Theses and Dissertations

Automatic fault detection and recovery would be a mandatory requirement for a satellite where some degree of autonomy is required. This thesis reviews some AI techniques used for the detection of satellite anomalies, and concludes that the model-based reasoning paradigm is best suited for automated on-board fault detection because it can cope with situations not necessarily programmed into the knowledge base. Using the Scheme language and its SCOOPS object oriented extension, development of software is described that models the pitch control channel in the attitude and velocity control subsystem of a typical geo-stationary communications satellite. This model is used by …

Development Of An Image Registration Technique For Polar-Orbiting Satellites, Jerry L. Mehlberg

Theses and Dissertations

In this thesis, a means to perform spatial registration (gridding) of meteorological satellite data is developed. It is applicable to Automatic Picture Transmission (APT) data from the TIROS-N series polar-orbiting satellites operated by the National Oceanic and Atmospheric Administration (NOAA). This technique does not require the use of ground control points. Registration is accomplished using an advanced orbital model to precisely compute the satellite's location based on NORAD two-line element sets and the time of the image. This technique is examined for accuracy and sensitivity to errors in the element set and satellite attitude control. This study involves over 70 …

Improving Reliability In A Stochastic Communication Network, William L. Gaught

Theses and Dissertations

This research investigated the behavior of increasing the reliability of components in stochastic communication networks. A stochastic communication network is one in which the components, links and nodes, are not 100 percent reliable. In addition the reliability value, each component also has a capacity value that limits the flow through the component. The throughput in a stochastic communication network can be improved by increasing the capacity or the reliability of the individual components. A set of linear and nonlinear models was developed to determine the best investment strategy for increasing the reliability of individual components. Once the models were developed, …

Turbulence Scales In The Passage Of A Linear Turbine Cascade, James L. Acree

Theses and Dissertations

Convective heat transfer in a turbine cascade is examined for turbulence effects. Turbulence in the free stream is varied by injection of air through a jet-grid device upstream of the cascade. Pressure and flow patterns on the blade surface, and flow velocity in two components, are examined to determine the effect of the jet-grid. Velocity and velocity fluctuation in two components are measured. Local turbulence scales through the cascade passage are determined, and local turbulent energy dissipation rate is determined. Results indicate injection of air through the jet-grid changes the angle of incidence, and therefore changes the surface pressures and …

Investigation Of The High Angle Of Attack Dynamics Of The F-15b Using Bifurcation Analysis, Robert J. Mcdonnell

Theses and Dissertations

Previous studies predicted the F-15B high angle of attack and flat spin behavior using bifurcation analysis. These studies varied control surface deflections to find equilibrium and periodic solutions. The purpose of this research was to use bifurcation analysis to predict the F-15B high angle attack and flat spin behavior as a result of variable thrust, asymmetric thrust, and thrust vectoring. Using a previously developed model of the F-15, bifurcation analysis and continuation methods were used to map out the equilibrium and periodic solutions of the model as a function of the thrust parameters. A baseline bifurcation diagram, as a function …

A Comparison Of Molecular Vibration Modeling For Thermal Nonequilibrium Airflow, Kenneth J. Moran

Theses and Dissertations

The effects of thermal nonequilibrium on flows about blunt-bodies have not been studied numerically in isolation from chemical reactions. Typically, air is modeled as a perfect gas or as a chemically reacting mixture. In the former case, significant errors result at Mach numbers exceeding about 5. However, below Mach numbers around 8, the effects of chemical reactions are negligible. This study analyzes flow about a simple axisymmetric blunt-body at moderate hypersonic speeds (Mach numbers between 5-8). A first-order-accurate Roe scheme was used to compute solutions of the Euler equations assuming different gas models: perfect gas, thermal equilibrium, and thermal nonequilibrium. …

Transverse Cracking In A Fiber Reinforced Ceramic Matrix Composite, Steven E. Bachmann

Theses and Dissertations

The purpose of this study was to investigate the transverse cracking behavior of a fiber reinforced ceramic matrix composite. The major objectives were to determine the crack initiation stress and the minimum transverse crack spacing for different cross-ply lay-ups of SiC/1723, to provide explanation for the differences in the performance of the lay-ups, and to compare the test results to available theoretical models and to other composite systems. The thickness of the transverse ply was found to have a great effect on the transverse cracking behavior of laminates. The saturation crack spacing decreased as the transverse ply thickness was decreased. …

Effects Of Specific Heat Ratio On A Simulated Chemical Laser Cavity Flow, Curt Dewayne Botts

Theses and Dissertations

Mixing of primary cold flow air and secondary helium to control the ratio of specific heats for the medium flowing through a simulated chemical laser nozzle/lasing cavity was accomplished. The effects of a range of mixture specific heat ratios on flowfield behavior were examined using static pressure ports in the test cavity. Schlieren photography and high speed filming aided description of the flow dynamics. Results indicated that boundary layer effects became evident in the nozzles as specific heat ratios increased. Large pressure fluctuations were observed in the cavity when helium was introduced into the flow to raise the specific heat …

Fracture Toughness Of Unidirectional Fiber Reinforced Ceramic Composites In Mode Ii Utilizing Laser Interferometry, Joseph W. Truskowski

Theses and Dissertations

A laser interferometry technique to measure crack opening displacement was developed and applied to end notched flexure specimens of a Corning Glass Works 1723 glass matrix with silicon carbide fibers. The laser interferometer displacement gauge monitored the crack opening displacement (COD) at the location of a support while specimens were subjected to Mode II (forward shear) cracking at room temperature via three point bend tests on a standard Instron Compression machine. Vertical displacement was measured at the center of the test specimen using a linear variable differential transformer. Load verses displacement curves were generated for both the LVDT displacement and …

Skin Friction And Heat Transfer Predictions For Hypersonic Turbulent Flow Over An Ogive-Cylinder, Richard H. Byers

Theses and Dissertations

The WRDC/FIMG Parabolized Navier-Stokes (PNS) Code is used to numerically predict both laminar and turbulent hypersonic flows over an ogive- cylinder body at zero angle of attack. A parametric study is conducted to determine the effects of selected code input variables on heat transfer and skin friction predictions. Comparisons are made between the PNS predictions and experimental data from the WRDC/Mach 6 High Reynolds Number Test Facility. Various problems encountered while obtaining PNS starting and marching solutions and corrective steps taken are discussed. A mesh resolution study indicates the minimum radial grid density sufficient for obtaining reasonable heat transfer results. …

Decomposition Of Measured Contours Into Geometric Features For Dimensional Inspection, Devaraj Rajkumar

Dissertations and Theses

Image processing systems used in Vision Assisted Dimensional Inspection usually output a set of boundary pixels representing the part edges. This boundary information must be divided into several subsets representing the various edges of the actual object, so that comparisons with the nominal part can be made.

The purpose of this project is to devise a method to divide the set of pixels obtained from the image processing system into subsets of pixels. Each of these subsets represent an edge in the contour of the actual object. This method must also detect transition points between the adjacent features. This project …

Minimum Orbits About The Planet Venus, Jeffrey J. Smith

Theses and Dissertations

An investigation is conducted into low orbiting satellites around the planet Venus with drag limited lifetimes. It is possible to specify combinations of orbital elements which result in orbital lifetimes in excess of some desired value. These combinations can be assembled into Critical Curves and Critical surfaces. Critical Curves and Surfaces are defined as curves and surfaces in orbital element space above which initial element sets will result in orbits that meet or exceed lifetime requirements. A numerical method is implemented for finding these combinations, and three Critical Surfaces are examined. A decay threshold is selected for bounding satellite lifetime. …

Analysis Of Parking Orbits For A Sts External Tank In Low Earth Orbit, James E. Cross

Theses and Dissertations

A study was conducted of a single external tank in low earth orbit. Criteria for a parking orbit are then defined. Various orbits are then selected by varying the semi-major axis, eccentricity, and inclination. The resulting equations of motion for each of the above orbits (including atmospheric drag and a 2x0 gravity model) are numerically integrated over a time span of 90 earth days. An examination was made of the lowest initial altitudes which allowed the external tank to remain in the orbit window.

Specification And Equivalence Verification Of Sequential Circuits Via Vhdl, Richard L. Miller

Theses and Dissertations

This research presents a merger of the specification and design capabilities of the Very High Speed Integrated Circuit (VHSIC) Hardware Description Language (VHDL) with a known verification method (UC Berkeley's verify software) in order to solve the design and verification problem of sequential circuits. The fruits of this research are a behavioral VHDL model for sequential circuit specification, a structural VHDL model for sequential circuit design, and a method for comparing two circuits described using these VHDL models in order to demonstrate circuit equivalence. The behavioral and structural VHDL models were developed and tested within the Intermetric's VHDL software support …

Analysis Of The Static And Dynamic Stability Of Elastic Structures Using The Finite Element Method, Mohamed Hassan Gadallah

Archived Theses and Dissertations

No abstract provided.

Dynamic Analysis Of A Combat Aircraft With Control Surface Failure, Marc Roy

Theses and Dissertations

An investigation was performed to analyze the dynamic stability characteristic of an aircraft which has sustained damage to a primary control surface. The analysis was performed using the existing functional form of actual wind tunnel data taken on an F-16 model. Two control schemes are used for trimming an F-16 that has sustained damage to its rudder. The first control scheme represent the basic aircraft, while the second allowed the horizontal tail ailerons to move independently from the flaperons. The investigation was conducted for one flight condition representative of the aircraft at cruise speed. Region in α/β (angle of attack)/(sideslip …

Numerical Analysis Of Critical Inclinations About The Planet Mars, Kenneth J. Hyatt

Theses and Dissertations

This study investigated critical inclinations about the planet Mars. Averaged equations of motion were numerically integrated over a time span of ten Earth years for various inclinations, eccentricities, and perigee heights. Each orbit (i.e. set of initial conditions) produced a standard deviation of the variations in eccentricity (SDE) and inclination (SDI). These were calculated using a polynomial approximation to the variations. Surface plots of SDI and SDE vs the initial conditions are then examined to ascertain the critical inclinations.