Engineering Commons^™

Wind Tunnel Testing For Drag Reduction Of An Aircraft Laser Turret, Christopher H. Snyder

Theses and Dissertations

This study investigated the use of aft-mounted fairings and splitter plates to reduce the drag of a half-scale aircraft laser turret. Forces, moments, and pressure distributions were measured in the AFIT 1.5-m (5-ft) wind tunnel at Reynolds numbers between 3x10⁵ and 9x10⁵ based on the turret diameter. Oil traces indicated the nature of the flow near the surface of the unmodified turret and the surrounding area. Tufts placed on the turret, fairings, and splitter plates showed changes in separation regions when configurations were changed. The flow around the turret was characterized by dominant vortices shedding from the top …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 14, Number 6, June 1998, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Simulation Of The Hybrid Fuzzy-Boolean Finite State Machine (Hfb-Fsm), Hamed Shakouri

Masters Theses

Several models of fuzzy finite-state automata have been proposed in the literature. One model which benefits from the existing algorithms for designing Boolean finite-state machines, has been proposed by J. L. Grantner [8]. This model, which is called Hybrid Fuzzy-Boolean Finite State Machine (HFB-FSM), along with its algorithmic design procedure, can be used for implementing dynamic linguistic systems [7,8,13]. In this thesis we have developed a simulation program for the HFB-FSM model using C++ programming language. In order to simulate a HFB-FSM model, the user provides the information defining the system's behavior. Based on the algorithm proposed in [8], the …

Evaluation Of Condition-Responsive Work Zone Traffic Controls At The I-75 Clays Ferry Bridge, Jerry G. Pigman, Kenneth R. Agent, Joel Weber

Kentucky Transportation Center Research Report

The objective of this study was to document the effectiveness of the application of advanced technologies for the real-time control and management of traffic in the work zone at the I 75 Clays Ferry Bridge reconstruction project. A description is given for each of the condition-responsive traffic control devices used on the project. A summary of the usage of each system is given along with a rating of its performance and effectiveness. The evaluation includes an analysis of accident data in the vicinity of the Clays Ferry Bridge for the period of January 1990 through June 1997. The possibility of …

Evaluation Of Kentucky's Driver License Point System, Kenneth R. Agent, Nick Stamatiadis, Jerry G. Pigman

Kentucky Transportation Center Research Report

The objectives of this study were to: a) summarize the characteristics of drivers in Kentucky involved in traffic crashes and b) evaluate and recommend improvements to Kentucky's driver license point system. Comparisons of driving record were made by driver age and sex. The relationship between violations and traffic crashes was analyzed. The change in driving record after various interventions was investigated. Based on a review of the point systems used in other states and the analysis of the driver's license file, a revised point system was recommended for use in Kentucky.

Image Processing Based On A Fuzzy Logic Edge Detection Algorithm, Jamshid Khazaai

Masters Theses

One of the major problems in image processing is that of efficient edge detection. This is because the automated determination of an edge requires a subjective interpretation of just what the image author intended to be an edge. By training an edge determination algorithm to be sensitive to edges in a consistent manner, efficiency can be improved. This is the central idea of this thesis in which I define edge occurrences for the intensity (monochrome) images using fuzzy sets.

Edge characteristic functions are proposed for detecting edge pixels within a desired block of an (intensity and binary) image based on …

Numerical Investigation Of An Airfoil With A Gurney Flap, Cory S. Jang, James C. Ross, Russell M. Cummings

Aerospace Engineering

A two-dimensional numerical investigation was performed to determine the effect of a Gurney flap on a NACA 4412 airfoil. A Gurney flap is a flat plate on the order of 1–3% of the airfoil chord in length, oriented perpendicular to the chord line and located on the airfoil windward side at the trailing edge. The flowfield around the airfoil was numerically predicted using INS2D, an incompressible Navier–Stokes solver, and the one-equation turbulence model of Baldwin and Barth. Gurney flap sizes of 0.5%, 1.0%, 1.25%, 1.5%, 2.0%, and 3.0% of the airfoil chord were studied. Computational results were compared with available …

Effect Of Temperature And Strain Rate On The Mechanical Behavior Of Al/Sic Particulates Metal Matrix Composites, Mohamed Mahmoud Zaki Emara

Archived Theses and Dissertations

No abstract provided.

Recycling Of Polysterene Foam And Other Polymeric Waste Materials, Elwathig Tibara Idris

Archived Theses and Dissertations

No abstract provided.

An Expert System Approach For Process Planning Of Rotational Components, Sherif Salah Raslan

Archived Theses and Dissertations

No abstract provided.

Cure-State Monitoring And Water-To-Cement Ratio Determination Of Fresh Portland Cement-Based Materials Using Near-Field Microwave Techniques, Karl Joseph Bois, Aaron D. Benally, Paul S. Nowak, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Quick and nondestructive determination of curestate and water-to-cement (w/c) ratio in fresh Portland cementbased materials is an important issue in the construction industry since the compressive strength of these materials is significantly influenced by w/c ratio. This is especially true since current techniques are not reliable and require a priori testing of test specimens as calibration for subsequent on-site monitoring of a cast in-place structure. Recently, the sensing of Portland cementbased materials using microwave techniques has received much attention. Microwave nondestructive techniques have already shown the potential for determining w/c ratio, sand-to-cement (s/c) ratio and coarse aggregate-to-cement (ca/c) ratio in …

Mixed Electron Emission From Lead Zirconate-Titanate Ceramics, Weiming Zhang, Wayne Huebner, Stephen E. Sampayan, Mike L. Krogh

Materials Science and Engineering Faculty Research & Creative Works

Simultaneous ferroelectric and plasma emission from Pb(Zr,Ti)O₃ was observed with only a negative driving pulse applied to the sample, and without an extraction potential on the electron collector. Plasma emission was a strong, inconsistent, and self-destructive process. In addition, a positive ion current was detected. Comparatively, ferroelectric emission was a relatively stable self-emission process, exhibiting no apparent delay time, and no positive ion current. The relationship between the switching and emission current of ferroelectric samples measured simultaneously cannot only be used to determine the existence of ferroelectric emission, but can also give direction to choosing suitable ferroelectric materials for …

Thickness Dependence Of Interfacial Magneto-Optic Effects, Xiang Gao, Michael J. Devries, Daniel W. Thompson, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Spectroscopic ellipsometry and magneto-optic Kerr effects are measured on Pt/Co multilayers with a series of Co layer thicknesses from 0.08 to 1 nm. An electromagnetic theory of multilayered structures allows regression analysis fits between acquired data and parameter dependent model analysis. Recently, we determined the single layer Co magneto-optic Voigt parameter and found that it depends on Co layer thickness. In the present work, we report an in-depth study of interfacial magneto-optic effects for a large number of Pt/Co multilayer samples. Kerr rotation and ellipticity were measured over the spectral range from 200 to 1700 nm. Voigt parameters of the …

Effects Of Clutter Height Distribution On Adaptive Clutter Erasure Performance, Kelce Steven Wilson

Theses and Dissertations

A new real beam interferometric processing technique, called Adaptive Clutter Erasure (ACE), is investigated for applicability to ground clutter suppression in airborne radar systems. By analysis and simulation, the viability of the ACE concept as a next generation clutter suppression technique is demonstrated to achieve performance enhancements commensurate with currently implemented techniques. Research results indicate the ACE concept provides a reliably consistent 10dB Signal-to-Clutter Ratio (SCR) advantage over the APG-63, an operational radar system used for baseline comparison. ACE system concept development and performance predictions are conducted in conformity with the physical and operational design parameters of the APG-63, namely …

High Amplitude Tracking Control, Joseph W. Mcnamee

Theses and Dissertations

The problem of tracking control in the face of high amplitude dynamic reference signals, hard state and control constraints, and open-loop unstable plants is investigated. Saturation effects mitigation is a current research topic, and a large body of literature exists which addresses this problem. However, with a few notable exceptions, little work has been accomplished which is applicable to the problem of high amplitude dynamic reference signal tracking in the face of hard state and control constraints, and open-loop unstable plants. Moreover, methods that do address the stated problem generally limit the exogenous reference signal to statically admissible values to …

Optimizing Conjunctive Water Use For Sustainable Production: Tools For The Management Spectrum, Richard C. Peralta, Shengjun J. Wu, H. J. Morel-Seytoux, Fernando Chanduvi

Civil and Environmental Engineering Faculty Publications

Making best use of water resources requires coordinating use of groundwater and surface waters--conjunctive use. Conjunctive water management is important on the regional (watershed or aquifer), water district and field scales. Goals might differ for the different administrative levels. A regionally optimal water management strategy is not necessarily optimal for water district managers and individual farmers. Interactions between levels are affected by laws, regulations, traditions and public pressure. To help each organizational level develop water management strategies that best achieve its goals, computer simulation/optimization (S/O) models are useful. Such S/O models couple water flow and transport simulation techniques with formal …

A Practical Algorithm For Designing H∞ Control Laws, Timothy Mclain, Randal W. Beard

Faculty Publications

We describe an approximation method for the Hamilton-Jacobi-Isaacs (HJI) equation that results in feedback control. The approximation is accomplished via a two-step successive Galerkin approximation scheme. An application of the technique to the control of the forward motion of an underwater vehicle is described.

Fuel Equalized Retargeting For Separated Spacecraft Interferometry, Timothy Mclain, Randal W. Beard, Fred Y. Hadaegh

Faculty Publications

Motivated by NASA's proposed Deep Space 3 interferometer mission, the paper considers the problem of reorienting a constellation of spacecraft such that the total fuel distributed across the constellation is both conserved and expended uniformly. The spacecraft constellation is controlled to reorient as if it were a rigid body. Two approaches to fuel equalization are investigated. The first approach picks a point of rotation a priori that optimizes an objective function that trades off minimum-fuel maneuvers and maneuvers that equalize the fuel. Since the point of rotation is selected a priori and is fixed during the rotation, this approach is …

Analytical And Experimental Study Of Investment Casting With Laser Stereolithography Models, Wen-Long Yao

Dissertations

This dissertation presents an analytical and experimental investigation of ceramic shell cracking during the burnout process in investment casting with internally webbed laser stereolithography (SLA) patterns. Included in the consideration are the cracking temperature of the ceramic shell, the web link buckling temperature, and the glass transition temperature of the epoxy resin. The hypothesis is that shell cracking will occur when the cracking temperature is lower than the glass transition temperature and the web buckling temperature.

An analytical and experimental study has been conducted, with the cross-sectional area, the span length of the web structure, and the shell thickness being …

A Combined Simulated Annealing And Tabu Search Strategy To Solve Network Design Problem With Two Classes Of Users, Qifeng Zeng

Dissertations

A methodology to solve a transportation network design problem (TCNDP) with two classes of users (passenger cars and trucks) is developed. Given an existing highway system, with a capital investment budget constraint, the methodology selects the best links to be expanded by an extra lane by considering one of three types of traffic operations: exclusive for passenger cars, exclusive for trucks, and for both passenger cars and trucks such that the network total user equilibrium (UE) travel time is minimized.

The problem is formulated as an NP-hard combinatorial nonlinear integer programming problem. The classical branch and bound methodology for the …

Automobile Air Bag Inflation System Using Pressurized Carbon Dioxide, Bart Adams

Dissertations

A novel air bag inflator based on the evaporation ofliquefied carbon dioxide was developed. A detailed qualitative model wasestablished on the basis of an extensive experimental study. An integratedquantitative model of this inflator was constructed.

The system was studied by discharging the inflatorinto a tank and measuring pressure and temperature evolution (0-50 ms). Thedispersion of the two-phase spray duringinflation was investigated by high-speed cinematography.

The optimal storage pressure of the liquid CO₂was found to be 2000 psig (at 22 °C). Two distinct inflator behaviors wereidentified. First, at conditions corresponding to an initial entropy below the critical point, atwo-phase …

Space-Time Reduced Rank Methods And Cfar Signal Detection Algorithms With Applications To Hprf Radar, Tareq F. Ayoub

Dissertations

In radar applications, the statistical properties (covariance matrix) of the interference are typically unknown a priori and are estimated from a dataset with limited sample support. Often, the limited sample support leads to numerically ill-conditioned radar detectors. Under such circumstances, classical interference cancellation methods such as sample matrix inversion (SMI) do not perform satisfactorily. In these cases, innovative reduced-rank space-time adaptive processing (STAP) techniques outperform full-rank techniques. The high pulse repetition frequency (HPRF) radar problem is analyzed and it is shown that it is in the class of adaptive radar with limited sample support. Reduced-rank methods are studied for the …

A Low-Cost High-Speed Twin-Prefetching Dsp-Based Shared-Memory System For Real-Time Image Processing Applications, Charalambos Stephanou Christou

Dissertations

This dissertation introduces, investigates, and evaluates a low-cost high-speed twin-prefetching DSP-based bus-interconnected shared-memory system for real-time image processing applications. The proposed architecture can effectively support 32 DSPs in contrast to a maximum of 4 DSPs supported by existing DSP-based bus- interconnected systems. This significant enhancement is achieved by introducing two small programmable fast memories (Twins) between the processor and the shared bus interconnect. While one memory is transferring data from/to the shared memory, the other is supplying the core processor with data. The elimination of the traditional direct linkage of the shared bus and processor data bus makes feasible the …

Removal Of Volatile Organic Compound (Voc) Vapors In Biotrickling Filters : Process Modeling And Validation With Chlorinated Aromatic Compounds, Christos J. Mpanias

Dissertations

This study dealt with the removal of vapors of volatile organic compounds from airstreams in biotrickling filters (BTFs). A detailed general model was developed for describing the process under steady-state conditions. The model accounts for mass transfer between phases (air, liquid, biofilm) and biodegradation of pollutants in the biofilm. It also accounts for potential kinetic interactions among pollutants as well as potential process limitations by oxygen availability.

The general model was experimentally validated using mono-chlorobenzene (m-CB) and ortho-dichlorobenzene (o-DCB) as model compounds either alone or in mixture with each other. Before BTF experiments were undertaken, a systematic kinetic study was …

Robust Fuzzyclustering For Object Recognition And Classification Of Relational Data, Sumit Sen

Dissertations

Prototype based fuzzy clustering algorithms have unique ability to partition the data while detecting multiple clusters simultaneously. However since real data is often contaminated with noise, the clustering methods need to be made robust to be useful in practice. This dissertation focuses on robust detection of multiple clusters from noisy range images for object recognition. Dave's noise clustering (NC) method has been shown to make prototype-based fuzzy clustering techniques robust. In this work, NC is generalized and the new NC membership is shown to be a product of fuzzy c-means (FCM) membership and robust M-estimator weight (or possibilistic membership). Thus …

Performance Improvements In Wireless Cdma Communications Utilizing Adaptive Antenna Arrays, Weichen Ye

Dissertations

This dissertation studies applications of adaptive antenna arrays and space-time adaptive processing (STAP) in wireless code-division multiple-access (CDMA) communications. The work addresses three aspects of the CDMA communications problems: (I) near-far resistance, (2) reverse link, (3) forward link. In each case, adaptive arrays are applied and their performance is investigated.

The near-far effect is a well known problem which affects the reverse link of CDMA communication systems. The near-far resistance of STAP is analyzed for two processing methods: maximal ratio combining and optimum combining. It. is shown that while maximal ratio combining is not near-far resistant, optimum combining is near-far …

Modelling Of In-Situ Bioremediation With Emphasis On Inhibitory Kinetics And Biomass Growth, Dilip Kumar Mandal

Dissertations

This thesis was motivated by the need for better engineering tools to predict the extent of contaminant plume migration in the saturated zone. The principal result was a mathematical model analogous to a catalytic packed-bed reactor, in which the subsurface was considered to be composed (conceptually) of soil aggregates (the "catalyst" particles, in which biodegradation, diffusion, and sorption take place), and a mobile phase (groundwater) passing around the aggregates, in which convection, axial diffusion, and mass transfer from the aggregates take place.

The modelling emphasis was on a more detailed exposition of the biokinetics of the system (including an inhibitory …

Plasma Enhanced Chemical Vapor Deposition Of Diamondlike Carbon Films Using Acetylene, Sriram Vishwanathan

Theses

This study is focussed on the synthesis and characterization of diamondlike carbon (DLQ films deposited on silicon wafers and glass by plasma enhanced chemical vapor deposition (PECVD), using acetylene (C₂H₄) as a precursor. The process parameters, such as temperature, pressure, power and reactant gas flow rate have been systematically varied and their effects on the film growth rate and properties were investigated. The optimized deposition condition appeared to be at 150°C, 200mTorr, 200 Watts and flow rate = 25 sccm. For these conditions, the films were hard and found to have good adhesion to the substrate, …

Fluorescence Spectroscopy For The Characterization Of Total Organic Carbon And Disinfection By-Product Formation, Matthew Brendan Washington

Theses

One of the concerns facing the drinking water industry is the formation of disinfection by-products (DBPs) during the disinfection stage of treatment. Organic DBPs form during the oxidation of the natural organic matter (NOM) found in natural waters by the application of a disinfectant, such as chlorine.

NOM is composed of two aggregate materials, humic and non-humic substances. It is unknown which portions of NOM react with the oxidant to form DBPs. Methods used to predict the formation of DBPs include total organic carbon (TOC) analysis and Trihalomethane Formation Potential (THMFP), which are time consuming and do not give specific …

Development Of A Practical And Effective Technique To Determine The Complete Level Of Autonomic Neural Activity During Stress, Vikki Hazelwood

Theses

Clinical evidence exists to suggest that an individual's level of stress contributes to the state of many physiological and psychological disorders, The autonomic nervous system, by adjusting parasympathetic and sympathetic activity, is attributed with the control over an individual's level of neural stress. Therefore, it is desired to develop a better and quantitative understanding of the stress! autonomic system mechanism.

Previous work has been done to gain a partial understanding of such activity. The primary objective for this study is to complement and advance the previous work by determining whether there is other physiological data which could reveal more about …