Engineering Commons^™

Evaluation Of Hazardous Material Life Cycle Cost Tools For Use In Air Force Hazardous Material Pharmacies, Rowene J. Resler

Theses and Dissertations

This research focuses on evaluation of various tools that assist in the selection of hazardous material substitutes. Substitute material consideration is a function of the Hazardous Material Pharmacy (HMP) when a hazardous material is requested for purchase and use in a current base operation. The substitute material decision is complex, involving identification of potential substitutes and then comparison of factors, such as cost, performance, and environmental effects, between the potential substitute and the material being requested. Various tools such as life cycle cost models, databases, and other information services can provide assistance to HMPs making substitution decisions.

Development Of A Basis For A Hazardous Materials And Waste Management System For Air Force Contingency Deployments, Christopher J. West

Theses and Dissertations

Increased awareness of the potential for adverse mission impact on deployments, recent experience on such deployments, and Air Force and Major Command interest establish the need for an integrated hazardous materials and waste management system for contingency environments. This research was focused toward establishing a basis for developing such a system. An intensive literature review was accomplished to justify the necessity of the research, characterize the contingency environment, review legal and regulatory requirements, review proper hazardous substance handling and processing procedures, and review existing and new material resources which may be employed in such a system. Further literature review led …

Development Of Object-Based Teleoperator Control For Unstructured Applications, Hyunki Cho

Theses and Dissertations

For multi-fingered end effectors in unstructured applications, the main issues are control in the presence of uncertainties and providing grasp stability and object manipulability. The suggested concept in this thesis is object based teleoperator control which provides an intuitive way to control the robot in terms of the grasped object and reduces the operator's conceptual constraints. The general control law is developed using a hierarchical control structure, i.e., human interface I gross motion control level in teleoperation control and fine motion control/object grasp stability in autonomous control. The gross motion control is required to provide the position/orientation of the Super …

Analysis Of Multimode Low-Probability-Of-Intercept (Lpi) Communications With Atmospheric Effects, Ala Ghordlo

Theses and Dissertations

This research expanded Low Probability of Intercept (LPI) communications analysis in two areas. First, multimode communication was included to account for ground to ground and air to ground links in addition to the standard air to air links traditionally used in LPI analysis. The propagation equations for the three modes of interest were derived and included in LPI analytic models in the form of a mode quality factor to account for multimode LPI scenarios. This new quality factor was used in studying several communication and interception link combinations. Variations due to differences between the communication and interception modes were presented …

Performance Analysis Of Preemption Algorithms In An Idnx Circuit Switch Communications Network, Eric C. Gumbs

Theses and Dissertations

Access to communication networks is increasing rapidly. The increase access to these networks results in delays and at times loss of data. At times of peak traffic or when trunks or nodes are down, very important customers' communications requirements are not met. One way to combat this problem is to prioritize the network and provide different levels of grade of service (GOS) for each priority. Call preemption provides an effective method of obtaining different levels of GOS. This research seeks to design the best circuit switch communications network preemption model for the DoD by analyzing previously developed preemption algorithms. Four …

Application Of A Finite-Volume Time-Domain Maxwell Equation Solver To Three-Dimensional Objects, Frederick G. Harmon

Theses and Dissertations

Concurrent engineering approaches for the disciplines of computational fluid dynamics (CFD) and electromagnetics (CEM) are necessary for designing future high-performance, low-observable aircraft. A characteristic-based finite-volume time-domain (FVTD) computational algorithm, developed for CFD and now applied to CEM, is implemented to analyze the radar cross section (RCS) of two three-dimensional objects, the ogive and cone-sphere. The FVTD formulation implements a Monotone Upstream-Centered Scheme for Conservation Laws (MUSCL) algorithm for the flux evaluation and a Runge-Kutta multi-stage scheme for the time integration. Developmental FVTD work for the thesis focused on algorithm development to analyze scattering and obtain RCS data for closed-surface perfect …

Performance Analysis Of Dynamic Routing Protocols In A Low Earth Orbit Satellite Data Network, Richard F. Janoso

Theses and Dissertations

Modern warfare is placing an increasing reliance on global communications. Currently under development are several Low Earth Orbit (LEO) satellite systems that propose to deliver voice and data traffic to subscribers anywhere on the globe. However, very little is known about the performance of conventional routing protocols under orbital conditions where the topology changes on a scale of minutes rather than days. This thesis compares two routing protocols in a LEO environment. One (Extended Bellman-Ford) is a conventional terrestrial routing protocol, while the other (Darting) is a new protocol which has been proposed as suitable for use in LEO networks. …

Adaptive Neural Network Controller For Atm Traffic, Jeffrey E. Larson

Theses and Dissertations

Broadband-Integrated Services Digital Networks (B-ISDN), along with Asynchronous Transfer Mode (ATM), were designed to meet the requirements of modern communication networks to handle multiple users and a wide variety of diverse traffic including voice, data and video. ATM responds to requests for admission to the network by analyzing whether or not the grade of service (GOS) requirement, specified in the admission request, can be guaranteed without violating the GOS guaranteed to traffic already accepted into the network. The GOS is typically a parameter such as cell loss rate (CLR), average delay, or some other measurement associated with network performance. In …

Multiple Model Adaptive Estimation And Control Redistribution For The Vista F-16, Robert W. Lewis Sr.

Theses and Dissertations

Performance characteristics of a Multiple Model Adaptive Estimation and Control Redistribution (MMAE/CR) algorithm are evaluated against single and double actuator and sensor failures. MMAE alone can compensate for sensor failures, whereas Control Redistribution compensates for actuator failures by redistributing commands, initially intended for failed actuators, to the unfailed actuators in such a way that the desired system response is achieved. Both failure detection and compensation capabilities are developed and analyzed through an extensive amount of simulation data, particularly addressing multiple failures. Simulations are performed utilizing the high fidelity, non-linear six degree of freedom Simulation Rapid Prototyping Facility for the VISTA …

Clustered Microcalcification Detection Using Optimized Difference Of Gaussians, Edward M. Ochoa

Theses and Dissertations

The objective of this thesis is to design an automated microcalcification detection system to be used as an aid in radiologic mammogram interpretation. This research proposes the following methodology for clustered microcalcification detection. First, preprocess the digitized film mammogram to reduce digitization noise. Second, spatially filter the image with a difference of Gaussians (DoG) kernel. To detect potential microcalcifications, segment the filtered image using global and local thresholding. Next, cluster and index these detections into regions of interest (ROIs). Identify ROIs on the digitized image (or hardcopy printout) for final radiologic diagnosis.

Optimization Of A Gps-Based Navigation Reference System, Jason B. Mckay

Theses and Dissertations

The development of increasingly accurate new aircraft navigation systems has caused the Air Force to develop a new Navigation Reference System to test them, called the Submeter Accuracy Reference System (SARS). The SARS is an inverted GPS system which consists of an array of GPS receivers on the ground and an airborne pseudolite mounted on the test aircraft. The SARS will provide a proof position estimate that is used to check the navigation system under test. Unfortunately, ground based inverted GPS systems tend to suffer from high geometric sensitivity to measurement errors. This research tackles the problem of optimizing the …

Interference Suppression For Spread Spectrum Signals Using Adaptive Beamforming And Adaptive Temporal Filter, Wonjin Park

Theses and Dissertations

Interference and jamming signals are a serious concern in an operational military communication environment. This thesis examines the utility and performance of combining adaptive temporal filtering with adaptive spatial filtering (i.e. adaptive beamforming) to improve the signal-to-jammer ratio (SJR) in the presence of narrowband and wideband interference. Adaptive temporal filters are used for narrowband interference suppression while adaptive beamforming is used to suppress wideband interference signals. A procedure is presented for the design and implementation of a linear constraints minimum variance generalized sidelobe canceler (LCMV-GSC) beamformer. The adaptive beamformer processes the desired signal with unity gain while simultaneously and adaptively …

Performance Analysis Of A Hartman Wavefront Sensor Used For Sensing Atmospheric Turbulence Statistics, Toby D. Reeves

Theses and Dissertations

Atmospheric turbulence parameters, such as Fried's coherence diameter, the outer scale of turbulence, and the turbulence power law, are related to the wavefront slope structure function (SSF). The SSF is defined as the second moment of the wavefront slope difference as a function of both time and position. Knowledge of the SSF allows turbulence parameters to be estimated. Hartmann wavefront sensor (H-WFS) slope measurements composed of both signal and noise, allow the SSF to be estimated by computing a mean square difference of H-WFS slope measurements. The quality of the SSF estimate is quantified by the signal-to-noise ratio (SNR) of …

Evaluation Of Design Tools For Rapid Prototyping Of Parallel Signal Processing Algorithms, James C. Savage

Theses and Dissertations

Digital signal processing (DSP) has become a popular method for handling not only signal processing, but communications, and control system applications. A DSP application of interest to the Air Force is high speed avionics processing. The real time computing requirements of avionics processing exceed the capabilities of current single chip DSP processors, and parallelization of multiple DSP processors is a solution to handle such requirements. Designing and implementing a parallel DSP algorithm has been a lengthy process often requiring different design tools and extensive programming experience. Through the use of integrated software development tools, rapid prototyping becomes possible by simulating …

Experimental Investigation Of Radar Cross Section Spatial Correlation Properties For A Point Scattering Target, John D. Shannon

Theses and Dissertations

This research investigates the spatial correlation of RCS. In pulsed radar systems, probability of detection for partially correlated signals depends on the autocovariance of the target's RCS. The RCS changes pulse to pulse due to spatial and time fluctuations. Spatial fluctuation are due to the motion of all scatterers relative to the radar (i.e. changing aspect angle). Time fluctuations are due to relative motion of scatterers to each other (i.e. wings flexing, engines spinning). Theory developed at AFIT [9] can generate autocovariance estimates from a distribution of scatterers. Theory based autocovariance estimates are compared to static measurement based autocovariance estimates …

Mmae Detection Of Interference/Jamming And Spoofing In A Dpgs-Aided Inertial System, Nathan A. White

Theses and Dissertations

Previous research at AFIT has resulted in the development of a DGPS-aided INS-based precision landing system (PLS) capable of meeting the FAA precision requirements for instrument landings. The susceptibility of DGPS transmissions to interference/jamming and spoofing must be addressed before DGPS may be used in such a safety-of-flight critical role. This thesis applies multiple model adaptive estimation (MMAE) techniques to the problem of detecting and identifying interference/jamming and spoofing failures in the DGPS signal. Such an MMAE is composed of a bank of parallel filters, each hypothesizing a different failure status, along with an evaluation of the current probability of …

High-Pressure Oxidation Rates For Large Coal And Char Particles, James A. Mathias

Theses and Dissertations

The main objective of this study was to investigate the factors that influence the oxidation rate of large (five to eight millimeters in diameter) coal and char particles. To accomplish this, experiments were performed in which the gas temperature, gas velocity, particle size, partial pressure of oxygen, and total pressure were varied. The experiments were performed with the cantilever balance attachment and the high pressure controlled profile reactor.

Approximately 90 combustion experiments were performed with Pittsburgh, Utah Blind Canyon, and Wyodak-Anderson coal. These experiments were performed at atmospheric pressure with air and varied gas temperature, gas velocity, and particle size. …

Corrosion Inhibitor For Reinforcing Steel In Concrete, Hanan Abdel Aziz Elnouhy

Archived Theses and Dissertations

No abstract provided.

Synergistic Decision-Making Systems: Using Models Of Decision-Making Behaviors And Resources To Design Better Decision-Making System, Ronald R. Carter

Masters Theses

Despite advances in decision-making systems, many practical issues remain unaddressed and much of the computer's potential for supporting decisions is unrealized. The existing systems are often limited to specific decision-making activities or domains, and they force the decision-maker to adopt a closed and inflexible way of doing things. What is needed is a new approach to building decision-making systems, one that is not focused on how decisions should be made, but on the behaviors and resources involved in decision-making and how they affect the results. This paper explores such an approach. It examines how models of decision-making behaviors and resources …

Digital Rosetta Stone: A Conceptual Model For Maintaining Long-Term Access To Digital Documents, Steven B. Robertson

Theses and Dissertations

Due to the rapid evolution of technology, future digital systems may not be able to read and/or interpret the digital recordings made by older systems, even if those recordings are still in good condition. This thesis addresses the problem of maintaining long-term access to digital documents and provides a methodology for overcoming access difficulties due to technological obsolescence. A review was conducted to determine the long-term access methods that have already been suggested by other researchers. These previously suggested methods are then combined with other ideas that were encountered and conceived while performing research for this project. The combination of …

Personnel Airdrop Risk Assessment Using Bootstrap Sampling, Wonsik Kim

Theses and Dissertations

Previous work on personnel airdrop problems involving jumpers has been (1) event-oriented entanglement rates, (2) number of canopy bumps, (3) landing injuries, and (4) deaths. The thesis expands this area of research by developing cumulative distribution functions of maximum possible chute entanglement risk for the C-17 using bootstrap techniques. By comparing the effects of various C-17 aircraft configurations on the entanglement CDF, this thesis shows that under certain configurations the risk of centerline entanglement for the C-17 is less than for the C-141.

Iswe: A Case Study Of Technology Transfer, Michael P.J. Benfield

Honors Capstone Projects and Theses

No abstract provided.

Countering The Effects Of Measurement Noise During The Identification Of Dynamical Systems, Odell R. Reynolds

Theses and Dissertations

Sensor noise is an unavoidable fact of life when it comes to measurements on physical systems, as is the case in feedback control. Therefore, it must be properly addressed during dynamic system identification. In this work, a novel approach is developed toward the treatment of measurement noise in dynamical systems. This approach hinges on proper stochastic modeling, and it can be adapted easily to many different scenarios, where it yields consistently good parameter estimates. The Generalized Minimum Variance algorithm developed and used in this work is based on the theory behind the minimum variance identification process, and the estimate produced …

Using Kriging To Interpolate Spatially Distributed Volumetric Medical Data, Stephen M. Matechik

Theses and Dissertations

Routine cases in diagnostic radiology require the interpolation of volumetric medical imaging data sets. Inaccurate renditions of interpolated volumes can lead to the misdiagnosis of a patient's condition. It is therefore essential that interpolated modality space estimates accurately portray patient space. Kriging is investigated in this research to interpolate medical imaging volumes. Kriging requires data to be spatially distributed. Therefore, magnetic resonance imaging (MRI) data is shown to exhibit spatially regionalized characteristics such that it can be modeled using regionalized variables and subsequently be interpolated using kriging. A comprehensive, automated, three-dimensional structural analysis of the MRI data is accomplished to …

Model Predictive Control Of Aerospace Systems, Derek W. Ebdon

Theses and Dissertations

The primary objective of this thesis is to explore the fault tolerance capabilities of a state space formulation of MPC. Subsequent to a simulated control surface failure on the F-18 High Alpha Research Vehicle (HARV), the MPC controller will attempt to maintain stability and nominal performance while tracking a setpoint. Secondary objectives include studying the effect of data sample rate and MPC horizon lengths on system performance. These objectives will be accomplished using Matlab to develop the MPC controller and Simulink to demonstrate its effectiveness through simulation.

Pulse Coupled Neural Networks For The Segmentation Of Magnetic Resonance Brain Images, Shane L. Abrahamson

Theses and Dissertations

This research develops an automated method for segmenting Magnetic Resonance (MR) brain images based on Pulse Coupled Neural Networks (PCNN). MR brain image segmentation has proven difficult, primarily due to scanning artifacts such as interscan and intrascan intensity inhomogeneities. The method developed and presented here uses a PCNN to both filter and segment MR brain images. The technique begins by preprocessing images with a PCNN filter to reduce scanning artifacts. Images are then contrast enhanced via histogram equalization. Finally, a PCNN is used to segment the images to arrive at the final result. Modifications to the original PCNN model are …

A Two-Phase Damped-Exponential Model For Speech Synthesis, H. Allan Arb

Theses and Dissertations

It is well known that there is room for improvement in the resultant quality of speech synthesizers in use today. This research focuses on the improvement of speech synthesis by analyzing various models for speech signals. An improvement in synthesis quality will benefit any system incorporating speech synthesis. Many synthesizers in use today use linear predictive coding (LPC) techniques and only use one set of vocal tract parameters per analysis frame or pitch period for pitch-synchronous synthesizers. This work is motivated by the two-phase analysis-synthesis model proposed by Krishnamurthy. In lieu of electroglottograph data for vocal tract model transition point …

Analysis And Optimization Of A Banyan Based Atm Switch By Simulations, Syed Sohel Hussain

Dissertations and Theses

Asynchronous Transfer Mode (ATM) is proposed technology to create a broadband (high speed) packet switching network capable of transporting wide variety of services including voice, video and data in an integrated manner. The main concern in designing the switching fabrics used in this technology are speed, throughput, delay and variance of delay. We analyze the performance by simulations of ATM switch based on Banyan network in the uniform traffic condition.

We compare the analytical results obtained from three-state model Yan and Jenq to the simulation results. Based on observation of simulation results, we propose non-blocking first stage (NBFS) to increase …

Demodulation Of Narrowband Radio Frequency Signals By Aliasing Sampling, Chun-Ching Lin

Dissertations and Theses

The objective of this thesis is to study the demodulation of narrowband radio frequency signals by aliasing sampling in order to reduce the sampling rate. The spectrum can be recreated at the lower frequency position by aliasing sampling. However, if the sampling rate is deviated from the desired one, error will occur. The sensitivity to the frequency error of aliasing sampling is studied.

One main reason of the deviation of the sampling rate is the frequency drifting of the local oscillator. Being able to compensate the oscillator drifting errors inexpensively, automatic frequency control (AFC) loops are important at receivers. Two …

Experimental Validation Of Finite Element Analysis Software Applied To The Design Of A Motorcycle Swingarm, Bret Schaller

Master's Theses - Daytona Beach

This thesis documents the experimental validation of finite element analysis software applied to the design of a motorcycle swingarm. The process includes design and implementation of an onboard data acquisition system; definition and measurement of operational loads; laboratory correlation of loads; experimental validation of Pro/Mechanica finite element analysis software; design and prototype development of a single-sided motorcycle swingarm; and computer modeling using the Pro/Engineer solid modeling package.