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2009

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Articles 2041 - 2070 of 4158

Full-Text Articles in Engineering

Full-Wave Based Validation Of Stripline Field Applicator For Low Frequency Material Measurements, James H. Crane Ii Mar 2009

Full-Wave Based Validation Of Stripline Field Applicator For Low Frequency Material Measurements, James H. Crane Ii

Theses and Dissertations

This research presents the analysis and verification of a stripline designed by Air Force Research Laboratory for use in measuring the electrical properties of materials at low frequencies and high temperature. It is designed to operate in the TEM mode up to 4 Ghz and have a characteristic impedance of 50 ohms. A full wave base method is used to analyze the structure. The parallel plate waveguide dyadic Green's function is developed for a current immersed in a PEC parallel plate environment. It is used to formulate a pair of coupled electric field integral equations (CIE). These CIEs are solved …

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Characterization Of Hardening By Design Techniques On Commercial, Small Feature Sized Field-Programmable Gate Arrays, Thomas E. Simmons Mar 2009

Characterization Of Hardening By Design Techniques On Commercial, Small Feature Sized Field-Programmable Gate Arrays, Thomas E. Simmons

Theses and Dissertations

In this thesis, a methodology is developed to experimentally test and evaluate a programmable logic device unde r gamma irradiation. The purpose of which is to determine the radiation effects and characterize the improvements of various hardening by design techniques. The techniques analyzed in this thesis include Error Correction Coding (ECC) and Triple Modular Redundancy (TMR). The TMR circuit includes three different functional implementations of adders compared to TMR voted circuits of those same adders. The TMR is implemented with the same functional adders and as a Functional TMR (FTMR) with three different function adders that are voted on. The …

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Application Of The Thermal Flash Technique For Low Thermal Diffusivity Micro/Nanofibers, Michael T. Demko, Zhenting Dai, Han Yan, William P. King, Miko Cakmak, Alexis R. Abramson Mar 2009

Application Of The Thermal Flash Technique For Low Thermal Diffusivity Micro/Nanofibers, Michael T. Demko, Zhenting Dai, Han Yan, William P. King, Miko Cakmak, Alexis R. Abramson

College of Polymer Science and Polymer Engineering

The thermal flash method was developed to characterize the thermal diffusivity of micro/nanofibers without concern for thermal contact resistance, which is commonly a barrier to accurate thermal measurement of these materials. Within a scanning electron microscope, a micromanipulator supplies instantaneous heating to the micro/nanofiber, and the resulting transient thermal response is detected at a microfabricated silicon sensor. These data are used to determine thermal diffusivity. Glass fibers of diameter 15 mu m had a measured diffusivity of 1.21x10(-7) m(2)/s; polyimide fibers of diameters 570 and 271 nm exhibited diffusivities of 5.97x10(-8) and 6.28x10(-8) m(2)/s, respectively, which compare favorably with bulk …

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The Utilization Of Light Gauge Steel In Residential Construction On The State Of Utah, Matthew Zaugg Perkins Mar 2009

The Utilization Of Light Gauge Steel In Residential Construction On The State Of Utah, Matthew Zaugg Perkins

Theses and Dissertations

This thesis researched why light gauge steel framing members are not used more in single-family residential construction. A survey was designed to extract information from licensed contractors in Utah on uses of light gauge steel framing members in residential homes. The purpose of the research was to discover what Utah builder's perception was concerning light gauge steel framing. Also, the researcher tried to learn a little about the contractors to see if there was a correlation between contractors that used light gauge steel and those that did not. Names of licensed general building contractors and residential contractors and their contact …

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Teaming Multi-Level Classes On Industry Projects, Lizabeth Schlemer, Jose Macedo Mar 2009

Teaming Multi-Level Classes On Industry Projects, Lizabeth Schlemer, Jose Macedo

Industrial and Manufacturing Engineering

For the past few years we experimented with teaming students from a sophomore-level class and a senior-level class to work on industry projects. The classes are “work design” and “facilities design.” Projects are selected to require the application of knowledge from both disciplines. In addition, the projects are selected from small local companies. The intent of this paper is to describe the benefits and difficulties associated with this methodology. While specific classes in this experience are typical of an industrial engineering curriculum, the lessons learned and benefits could translate to other disciplines.

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Modeling And Simulation Architecture For Studying Doppler-Based Radar With Complex Environments, Nicholas J. Amato Mar 2009

Modeling And Simulation Architecture For Studying Doppler-Based Radar With Complex Environments, Nicholas J. Amato

Theses and Dissertations

This research effort develops a hybrid large-scale modeling and simulation frame- work that defines the requirements for a program to evaluate radar-aircraft-turbine- clutter interactions. Wind turbines and other moving structures can interfere with a radar’s ability to detect moving aircraft because radar returns from turbines are comparable to those from slow flying aircraft. This interference can lead to aircraft collisions or crashes, reducing the safety for air traffic. Two radar applications, INSSITE and IMOM, were investigated to determine which of the subsystems, in the proposed architecture, are currently available and which need additional development. Current radar applications either delve too …

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Reusable Launch Vehicle Design Implications For Regeneration Time, Carlos Alberto Molina Mar 2009

Reusable Launch Vehicle Design Implications For Regeneration Time, Carlos Alberto Molina

Theses and Dissertations

In last few years, the Air Force Research Laboratory sponsored several research projects on a Reusable Launch Vehicles (RLV) whose design, operation, and logistics requirements are intended to be much simpler than for the Space Shuttle. As a part of these efforts, previous researchers developed a model that simulated the post-landing, ground maintenance and prelaunch operations of a RLV in order to evaluate how its design parameters affect the logistics operations. The next logical step is to investigate the effects and interactions of all factors used in the existing simulation model in a single experiment that considers the huge number …

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Denoising Using Adaptive Thresholding And Higher Order Statistics, Samuel Peter Kozaitis, Tim Young Mar 2009

Denoising Using Adaptive Thresholding And Higher Order Statistics, Samuel Peter Kozaitis, Tim Young

Electrical Engineering and Computer Science Faculty Publications

We showed that a hard threshold for wavelet denoising based on higher order statistics is comparable to a second order soft threshold. The hard threshold can be made adaptive by using a third order statistic as an estimate of the noise. In addition, the relationship between an adaptive hard threshold and retaining a fraction of wavelet coefficients is shown. Qualitative and quantitative metrics based on the mean-squared error are used to compare the hard thresholding and a soft-thresholding technique, BayesShrink.

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Decisive Routing And Admission Control According To Quality Of Service Constraints, Cindy C. Reese Mar 2009

Decisive Routing And Admission Control According To Quality Of Service Constraints, Cindy C. Reese

Theses and Dissertations

This research effort examines, models, and proposes options to enhance command and control for decision makers when applied to the communications network. My goal is to research the viability of combining three students’ past research efforts and expanding and enhancing those efforts. The area of this research is predicting a snapshot of the communications network, context-aware routing between network nodes, and Quality of Service-based routing optimization in order to create an intelligent routing protocol platform. It will consolidate efforts from an Intelligent Agent Based Framework to Maximize Information Utility by Captain John Pecarina, Dialable Cryptography for Wireless Networks by Major …

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Evaluation Of Air Force Aircraft Maintenance Metrics For Integration Into The Expeditionary Combat Support System, Brian D. Waller Mar 2009

Evaluation Of Air Force Aircraft Maintenance Metrics For Integration Into The Expeditionary Combat Support System, Brian D. Waller

Theses and Dissertations

All organizations face the continuous challenge of a dynamic and ever-changing operations environment. They must adapt to new paradigms quickly or end up on the road to obsolescence. Never has this been truer for the U.S. Air Force than in the 21st century. The logistics organization of the Air Force supports a worldwide, 24/7 operation, executing the national directive of US Policy. Past logistics operation policies have now been proven to no longer be sufficient to meet the needs of the war-fighter. Shrinking budgets, aging equipment, and the austere, disparate operating locations demand sweeping changes in how the logistic machine …

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Simulation Modeling Of The C-5 Galaxy High Velocity Regionalized Isochronal (Hvriso) Inspection Concept, Theodore K. Heiman Mar 2009

Simulation Modeling Of The C-5 Galaxy High Velocity Regionalized Isochronal (Hvriso) Inspection Concept, Theodore K. Heiman

Theses and Dissertations

Faced with eroding budgets, Air Mobility Command (AMC) is confronted with implementing simultaneous changes to its isochronal (ISO) inspection process for C-5 aircraft. C-5 inspection criteria will use a Maintenance Steering Group-3 (MSG-3) approach beginning in October, 2009. MSG-3 has been used successfully in civilian aviation since 1980 and AMC hopes to produce similar results. AMC is also consolidating the four docks presently in use to three high-velocity regionalized isochronal (HVRISO) docks. Centralized scheduling by AMC should utilize a dock selection method that minimizes both processing time and queue time when arriving aircraft cannot be immediately inducted into the servicing …

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Carbon Nanotube Membranes For Use In The Transdermal Treatment Of Nicotine Addiction And Opioid Withdrawal Symptoms, Caroline L. Strasinger, Nicole N. Scheff, Ji Wu, Bruce J. Hinds, Audra L. Stinchcomb Mar 2009

Carbon Nanotube Membranes For Use In The Transdermal Treatment Of Nicotine Addiction And Opioid Withdrawal Symptoms, Caroline L. Strasinger, Nicole N. Scheff, Ji Wu, Bruce J. Hinds, Audra L. Stinchcomb

Pharmaceutical Sciences Faculty Publications

Transdermal systems are attractive methods of drug administration specifically when treating patients for drug addiction. Current systems however are deficient in therapies that allow variable flux values of drug, such as nicotine for smoking cessation or complex dosing regimens using clonidine when treating opioid withdrawal symptoms. Through the use of functionalized carbon nanotube (CNT) membranes, drug delivery to the skin can be controlled by applying a small electrical bias to create a programmable drug delivery system. Clearly, a transdermal patch system that can be tailored to an individual's needs will increase patient compliance as well as provide much more efficient …

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The Design And Verification Of A Mems Combustor Chamber, Constance Yvonne Meadors Mar 2009

The Design And Verification Of A Mems Combustor Chamber, Constance Yvonne Meadors

Theses and Dissertations

A pre-combustion micro-mixing chamber has been designed as a component of the University of Arkansas at Little Rock's (UALR) proposed complete microelectromechanical (MEMS) hybrid rocket on a silicon chip. A MEMS pre-combustion mixer allows identification of pressures and flow rates for stochiometric mixing of combustion gases. The pre-combustion mixer has been designed to interface with a mass spectrometer for detection and characterization of combustion reactants and products as the first stage of a UALR hybrid micro-thruster. This research focuses on the design, fabrication, and validation of a pre-combustion micro-mixer that satisfies the requirements of MEMS micro-spacecraft and operates in space …

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Using Oceanic-Atmospheric Oscillations For Long Lead Time Streamflow Forecasting, Ajay Kalra, Sajjad Ahmad Mar 2009

Using Oceanic-Atmospheric Oscillations For Long Lead Time Streamflow Forecasting, Ajay Kalra, Sajjad Ahmad

Civil and Environmental Engineering and Construction Faculty Research

We present a data-driven model, Support Vector Machine (SVM), for long lead time streamflow forecasting using oceanic-atmospheric oscillations. The SVM is based on statistical learning theory that uses a hypothesis space of linear functions based on Kernel approach and has been used to predict a quantity forward in time on the basis of training from past data. The strength of SVM lies in minimizing the empirical classification error and maximizing the geometric margin by solving inverse problem. The SVM model is applied to three gages, i.e., Cisco, Green River, and Lees Ferry in the Upper Colorado River Basin in the …

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Performance Enhancements Of Ranging Radio Aided Navigation, Patric J. Ernsberger Mar 2009

Performance Enhancements Of Ranging Radio Aided Navigation, Patric J. Ernsberger

Theses and Dissertations

Determining the position of team members is always useful information, whether it is a team of firefighters fighting a blaze or combatants clearing a building in the field. This information becomes even more decisive for the people responsible for their safety. To accomplish this in areas denied Global Navigation Satellite System (GNSS), such as around buildings or in steep valleys, alternative methods must be used. Radio ranging systems have been a part of the navigation solution for years. They unfortunately have poor performance in certain areas, such as inside buildings, due to multipath and other errors. To improve the position …

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A Taxonomy For And Analysis Of Anonymous Communications Networks, Douglas J. Kelly Mar 2009

A Taxonomy For And Analysis Of Anonymous Communications Networks, Douglas J. Kelly

Theses and Dissertations

Any entity operating in cyberspace is susceptible to debilitating attacks. With cyber attacks intended to gather intelligence and disrupt communications rapidly replacing the threat of conventional and nuclear attacks, a new age of warfare is at hand. In 2003, the United States acknowledged that the speed and anonymity of cyber attacks makes distinguishing among the actions of terrorists, criminals, and nation states difficult. Even President Obama’s Cybersecurity Chief-elect recognizes the challenge of increasingly sophisticated cyber attacks. Now through April 2009, the White House is reviewing federal cyber initiatives to protect US citizen privacy rights. Indeed, the rising quantity and ubiquity …

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Computational Analysis Of Geometric Effects On Strut Induced Mixing In A Scramjet Combustor, Matthew G. Bagg Mar 2009

Computational Analysis Of Geometric Effects On Strut Induced Mixing In A Scramjet Combustor, Matthew G. Bagg

Theses and Dissertations

In order to increase the fuel-air mixing in a scramjet combustion section, the Air Force Institute of Technology and the Air Force Research lab investigated methods to increase the mixing efficiency. Previous experimental work identified the advantages of using a strut upstream of a cavity flame holder to increase the fuel-air mixture. In this paper a computational investigation of strut injectors in a supersonic flow with a cavity flame holder is reported. This research focused on understanding the effect of a change in height and width of the strut upstream of the combustion cavity on the mixing efficiency and pressure …

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Effect Of Steam Environment On Creep Behavior Of Nextel720/Alumina-Mullite Ceramic Matrix Composite At Elevated Temperature, Tolga Kutsal Mar 2009

Effect Of Steam Environment On Creep Behavior Of Nextel720/Alumina-Mullite Ceramic Matrix Composite At Elevated Temperature, Tolga Kutsal

Theses and Dissertations

The tensile creep behavior of an oxide-oxide ceramic matrix composite (CMC) was investigated at 1000 and 1100° C in laboratory air and steam. The oxide-oxide CMC studied in this research was Nextel™ 720/alumina-mullite (N720/AM). The composite consists of N720/fibers with 0°/90° fiber orientation and a porous alumina-mullite matrix. Tensile-strain behavior was investigated and tensile properties measured at 900, 1000 and 1100° C. The effect of loading rate on tensile properties of N720/AM ceramic matrix composite at 1100° C in steam was also examined. Creep-rupture tests were performed at 1100° C in laboratory air and steam, and at 1000° C only …

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An Investigative Study Of The Difficulties Experienced By Engineers Transitioning Into Leadership/Management Positions, Joseph Alan Wilde Mar 2009

An Investigative Study Of The Difficulties Experienced By Engineers Transitioning Into Leadership/Management Positions, Joseph Alan Wilde

Theses and Dissertations

The traditional engineering career has been defined by two career paths: technical and managerial. An entry level engineer typically did not elect his/her career path until at least five years into a career. This meant that only a portion of engineers needed to learn management and leadership skills and then usually not until in the professional environment. Since this career distinction was not made until years into an engineer's professional life universities were not developing leadership/management skills in their students. Times have changed. With the globalization of the economy, and the increased competition in the marketplace, companies have realized that …

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Safety Management Systems Update And Progress, Alan J. Stolzer Mar 2009

Safety Management Systems Update And Progress, Alan J. Stolzer

Publications

The Safety Management System (SMS) Day Panel Charge on March 18, 2009, delivered by Dr. Alan Stolzer, was intended to provide participants with references, tools, vocabulary, and encouragement to adopt academic and laboratory curricula that would prepare students for careers in the SMS environment.

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Automated Ellipsometer And The Like Systems, Blaine D. Johs, Ping He, Martin M. Liphardt, Christopher A. Goeden, John A. Woollam, James D. Welch Mar 2009

Automated Ellipsometer And The Like Systems, Blaine D. Johs, Ping He, Martin M. Liphardt, Christopher A. Goeden, John A. Woollam, James D. Welch

Department of Electrical and Computer Engineering: Faculty Publications

Systems and methodology for orienting the tip/tilt and vertical height of samples, preferably automated, as applied in ellipsometer and the like systems.

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Continuous Production Of Aligned Carbon Nanotubes, David N. Jacques, Rodney Andrews Mar 2009

Continuous Production Of Aligned Carbon Nanotubes, David N. Jacques, Rodney Andrews

Center for Applied Energy Research Faculty Patents

An apparatus for continuous production of aligned carbon nanotubes is disclosed. The apparatus includes a reactor, an injector for delivering a feed solution into the reactor, and a conveyor for passing through the reactor a substrate on which nanotubes may be formed and grown. The apparatus further may include an inert, porous medium through which the feed solution may be passed. The apparatus produces aligned carbon nanotubes of a predetermined external diameter, and is suitable for large scale production of aligned carbon nanotubes in an industrial setting.

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An Engineering Trade Space Analysis For A Space-Based Hyperspectral Chromotomographic Scanner, Phillip Sheirich Mar 2009

An Engineering Trade Space Analysis For A Space-Based Hyperspectral Chromotomographic Scanner, Phillip Sheirich

Theses and Dissertations

Hyperspectroscopy for fast transient events such as battlefield explosions is an undeveloped area of spectral imaging. This thesis is a discussion of issues involved with taking a laboratory design for a rotating prism hyperspectral chromotomographic (CT) instrument and producing a first approximation satellite payload design, operating scheme and trade space analysis to support demonstration of this technology in low-earth orbit. This instrument promises the capability of adding a time dimension to the normal spatial and spectral data produced by most hyperspectral imagers. The ultimate goal is to conduct experiments demonstrating the ultimate viability of spectral definition of transient combustion events …

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Satellite Reentry Control Via Surface Area Amplification, Salvador Alemán Mar 2009

Satellite Reentry Control Via Surface Area Amplification, Salvador Alemán

Theses and Dissertations

This project endeavors to find whether it is feasible to use an increase in surface area as a way of increasing the drag on an orbiting object, thus decreasing its orbital lifetime. The surface area increase can be achieved by an apparatus that deploys a balloon. The balloon will act as a parachute that will decrease the potential energy of the object through atmospheric drag. This is most effective by objects that reach the Low Earth altitudes of less than 500 kilometers, where an object is encountering a firmer atmospheric density. The project is carried out through propagating three different …

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Blind Deconvolution Through Polarization Diversity Of Long Exposure Imagery, Steven P. James Mar 2009

Blind Deconvolution Through Polarization Diversity Of Long Exposure Imagery, Steven P. James

Theses and Dissertations

The purpose of the algorithm developed in this thesis was to create a post processing method that could resolve objects at low signal levels using polarization diversity and no knowledge of the atmospheric seeing conditions. The process uses a two-channel system, one unpolarized image and one linearly polarized image, in a GEM algorithm to reconstruct the object. Previous work done by Strong showed that a two-channel system using polarization diversity on short exposure imagery could produce images up to twice the diffraction limit. In this research, long exposure images were simulated and a simple Kolmogorov model used. This allowed for …

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Unified Behavior Framework In An Embedded Robot Controller, Stephen S. Lin Mar 2009

Unified Behavior Framework In An Embedded Robot Controller, Stephen S. Lin

Theses and Dissertations

Robots of varying autonomy have been used to take the place of humans in dangerous tasks. While robots are considered more expendable than human beings, they are complex to develop and expensive to replace if lost. Recent technological advances produce small, inexpensive hardware platforms that are powerful enough to match robots from just a few years ago. There are many types of autonomous control architecture that can be used to control these hardware platforms. One in particular, the Unified Behavior Framework, is a flexible, responsive control architecture that is designed to simplify the control system’s design process through behavior module …

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La0.85Sr0.15Mno3− Infiltrated Y0.5Bi1.5O3 Cathodes For Intermediate-Temperature Solid Oxide Fuel Cells, Jiang Zhiyi, Changrong Xia, Fei Zhao, Fanglin Chen Mar 2009

La0.85Sr0.15Mno3− Infiltrated Y0.5Bi1.5O3 Cathodes For Intermediate-Temperature Solid Oxide Fuel Cells, Jiang Zhiyi, Changrong Xia, Fei Zhao, Fanglin Chen

Faculty Publications

Porous yttria-stabilized bismuth oxides (YSB) were investigated as the backbones for (LSM) infiltrated cathodes in intermediate-temperature solid oxide fuel cells. The cathodes were evaluated using anode-supported single cells with scandia-stabilized zirconia as the electrolytes. With humidified as the fuel, the cell showed peak power density of 0.33, 0.52, and at 650, 700, and , respectively. At , the cell polarization resistance was only , of the lowest value previously reported, indicating that YSB is a promising backbone for the LSM infiltrated cathode.

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Automated Ellipsometer And The Like Systems, Blaine D. Johs, Ping He, Martin M. Liphardt, Christopher A. Goeden, Johns A. Woollam, James D. Welch Mar 2009

Automated Ellipsometer And The Like Systems, Blaine D. Johs, Ping He, Martin M. Liphardt, Christopher A. Goeden, Johns A. Woollam, James D. Welch

Department of Electrical and Computer Engineering: Faculty Publications

Systems and methodology for orienting the tip/tilt ad vertical height of samples, preferably automated, as applied in ellipsometer and the like systems

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Critical Design Parameters For Pylon-Aided Gaseous Fuel Injection Upstream Of A Flameholding Cavity, Mitchell R. Pohlman Mar 2009

Critical Design Parameters For Pylon-Aided Gaseous Fuel Injection Upstream Of A Flameholding Cavity, Mitchell R. Pohlman

Theses and Dissertations

The Air Force Institute of Technology and the AFRL are investigating means to increase the efficiency of fuel-air mixing into supersonic flow. Previous work has shown much promise in increasing the penetration and mixing of a fuel-air mixture into the freestream by injecting fuel behind small triangular pylons. Pylon-aided fuel injection has also shown to lift the fuel plume off the combustor floor; this floor-gap prevents the ignition of fuel seeded in the boundary layer. In this paper twenty-one pylons of varying widths, heights, and lengths were examined in four specific test matrices within a CFD environment. Pylons in test …

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Using A Multiobjective Approach To Balance Mission And Network Goals Within A Delay Tolerant Network Topology, Anthony L. Larweck Mar 2009

Using A Multiobjective Approach To Balance Mission And Network Goals Within A Delay Tolerant Network Topology, Anthony L. Larweck

Theses and Dissertations

This thesis investigates how to incorporate aspects of an Air Tasking Order (ATO), a Communications Tasking Order (CTO), and a Network Tasking Order (NTO) within a cognitive network framework. This was done in an effort to aid the commander and or network operator by providing automation for battlespace management to improve response time and potential inconsistent problem resolution. In particular, autonomous weapon systems such as unmanned aerial vehicles (UAVs) were the focus of this research This work implemented a simple cognitive process by incorporating aspects of behavior based robotic control principles to solve the multi-objective optimization problem of balancing both …

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