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Theses and Dissertations

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Articles 7951 - 7980 of 11510

Full-Text Articles in Engineering

Dynamic Interactions For Network Visualization And Simulation, Cigdem Yetisti Mar 2009

Dynamic Interactions For Network Visualization And Simulation, Cigdem Yetisti

Theses and Dissertations

Most network visualization suites do not interact with a simulator, as it executes. Nor do they provide an effective user interface that includes multiple visualization functions. The subject of this research is to improve the network visualization presented in the previous research [5] adding these capabilities to the framework. The previous network visualization did not have the capability of altering specific visualization characteristics, especially when detailed observations needed to be made for a small part of a large network. Searching for a network event in this topology might cause large delays leading to lower quality user interface. In addition to …

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Using Predictive Rendering As A Vision-Aided Technique For Autonomous Aerial Refueling, Adam D. Weaver Mar 2009

Using Predictive Rendering As A Vision-Aided Technique For Autonomous Aerial Refueling, Adam D. Weaver

Theses and Dissertations

This research effort seeks to characterize a vision-aided approach for an Unmanned Aerial System (UAS) to autonomously determine relative position to another aircraft in a formation, specifically to address the autonomous aerial refueling problem. A system consisting of a monocular digital camera coupled with inertial sensors onboard the UAS is analyzed for feasibility of using this vision-aided approach. A three-dimensional rendering of the tanker aircraft is used to generate predicted images of the tanker as seen by the receiver aircraft. A rigorous error model is developed to model the relative dynamics between an INS-equipped receiver and the tanker aircraft. A …

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Abstracting Gis Layers From Hyperspectral Imagery, Torsten E. Howard Mar 2009

Abstracting Gis Layers From Hyperspectral Imagery, Torsten E. Howard

Theses and Dissertations

Modern warfare methods in the urban environment necessitates the use of multiple layers of sensors to manage the battle space. Hyperspectral imagers are one possible sensor modality to provide remotely sensed images that can be converted into Geographic Information Systems (GIS) layers. GIS layers abstract knowledge of roads, buildings, and scene content and contain shape files that outline and highlight scene features. Creating shape files is a labor-intensive and time-consuming process. The availability of shape files that reflect the current configuration of an area of interest significantly enhances Intelligence Preparation of the Battlespace (IPB). The solution presented in this thesis …

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Tools For The Conceptual Design And Engineering Analysis Of Micro Air Vehicles, Mustafa Turan Mar 2009

Tools For The Conceptual Design And Engineering Analysis Of Micro Air Vehicles, Mustafa Turan

Theses and Dissertations

Micro Air Vehicles (MAV) are a subset of Unmanned Aircraft (UAS) that are up to two orders of magnitude smaller than manned systems. Near-Earth environments, such as forests, caves, tunnels and urban structures make reconnaissance, surveillance and search-and-rescue missions difficult and dangerous to accomplish. Therefore, MAVs are considered ideal for these types of missions. However, the data using full size aircraft is inadequate to characterize miniature aircraft parameters due to the lower Reynolds numbers and low aspect ratio (LAR) wings and impact of wing-propeller interactions. The main objectives of this research were to: collect and synthesize the available data/tools; create …

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Optimized Robust Adaptive Networks In Supervisory Control And Data Acquisition Systems, Luis A. Oquendo Class Mar 2009

Optimized Robust Adaptive Networks In Supervisory Control And Data Acquisition Systems, Luis A. Oquendo Class

Theses and Dissertations

This thesis investigates the application of a Exponential Weighted Moving Average (EWMA) to be used as a memory buffer in conjunction with Special Protection Schemes (SPS) using the Electric Power and Communication Synchronizing Simulator (EPOCHS). It is proposed that using an SPS incorporating EWMA can compensate for the network layer lack of guarantee of packet delivery and provide for the stability and integrity of the power grid under a catastrophic event. The performance of the proposed SPS is evaluated using a discrete event computer simulation developed using the NS2 network simulator and the Power System Simulator for Engineering (PSS/E) power …

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Stochastic Estimation And Control Of Queues Within A Computer Network, Mingook Kim Mar 2009

Stochastic Estimation And Control Of Queues Within A Computer Network, Mingook Kim

Theses and Dissertations

Captain Nathan C. Stuckey implemented the idea of the stochastic estimation and control for network in OPNET simulator. He used extended Kalman filter to estimate packet size and packet arrival rate of network queue to regulate queue size. To validate stochastic theory, network estimator and controller is designed by OPNET model. These models validated the transient queue behavior in OPNET and work of Kalman filter by predicting the queue size and arrival rate. However, it was not enough to verify a theory by experiment. So, it needed to validate the stochastic control theory with other tools to get high validity. …

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A Feasibility Study Of A Persistent Monitoring System For The Flight Deck Of U.S. Navy Aircraft Carriers, Jeffrey S. Johnston Mar 2009

A Feasibility Study Of A Persistent Monitoring System For The Flight Deck Of U.S. Navy Aircraft Carriers, Jeffrey S. Johnston

Theses and Dissertations

This research analyzes the use of modern Real Time Locating Systems (RTLS), such as the Global Positioning System (GPS), to improve the safety of aircraft, equipment, and personnel onboard a United States Navy (USN) aircraft carrier. The results of a detailed analysis of USN safety records since 1980 show that mishaps which could potentially be prevented by a persistent monitoring system result in the death of a sailor nearly every other year and account for at least $92,486,469, or 5.55% of the total cost of all flight deck and hangar bay related mishaps. A system to continually monitor flight deck …

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Real-Time Wind Estimation And Video Compression Onboard Miniature Aerial Vehicles, Andres Felipe Rodriguez Perez Mar 2009

Real-Time Wind Estimation And Video Compression Onboard Miniature Aerial Vehicles, Andres Felipe Rodriguez Perez

Theses and Dissertations

Autonomous miniature air vehicles (MAVs) are becoming increasingly popular platforms for the collection of data about an area of interest for military and commercial applications. Two challenges that often present themselves in the process of collecting this data. First, winds can be a significant percentage of the MAV's airspeed and can affect the analysis of collected data if ignored. Second, the majority of MAV's video is transmitted using RF analog transmitters instead of the more desirable digital video due to the computational intensive compression requirements of digital video. This two-part thesis addresses these two challenges. First, this thesis presents an …

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The Evaluation Of Rekeying Protocols Within The Hubenko Architecture As Applied To Wireless Sensor Networks, Cory J. Antosh Mar 2009

The Evaluation Of Rekeying Protocols Within The Hubenko Architecture As Applied To Wireless Sensor Networks, Cory J. Antosh

Theses and Dissertations

This thesis investigates the impact of using three different rekeying protocols–pair-wise, hierarchical, and Secure Lock within a wireless sensor network (WSN) under the Hubenko architecture. Using a Matlab computer simulation, the impact of the three rekeying protocols on the number of bits transmitted across the network and the amount of battery power consumed in WSN nodes during rekey operations is investigated. Baseline pair-wise rekeying performance can be improved by using either Secure Lock or hierarchical rekeying. The best choice depends on the size of the WSN and the size of the key used. Hierarchical rekeying is the best choice for …

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Ohio River Denial As A Transportation Corridor And Its Economic Impacts On The Energy Industry, Caglar Utku Guler Mar 2009

Ohio River Denial As A Transportation Corridor And Its Economic Impacts On The Energy Industry, Caglar Utku Guler

Theses and Dissertations

What if the Ohio River is disrupted or denied partially or completely as a transportation corridor? A disruption may be either a natural or man-made disaster or a planned outage on the river’s lock and dam structures. Recent history is full of water transport disruption events having significant economic effects on the waterside industries. To assess coal-based economic impacts, we developed a network flow model to represent waterside coal-fired power plants situated along the Ohio River, their respective coal supplying mines, and the various transportation modes that connect them. We show that significant transportation-centric insights can be derived by using …

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Utilizing Microelectromechanical Systems (Mems) Micro-Shutter Designs For Adaptive Coded Aperture Imaging (Acai) Technologies, Mary M. Ledet Mar 2009

Utilizing Microelectromechanical Systems (Mems) Micro-Shutter Designs For Adaptive Coded Aperture Imaging (Acai) Technologies, Mary M. Ledet

Theses and Dissertations

The Air Force has long relied on surveillance for intelligence and strategic purposes. Most surveillance systems rely on a lensing system to acquire their images, most of which are in either the visible or infrared wavelengths. Because lensing systems can be expensive, obtrusive, or hard to maintain, researchers have designed adaptive coded aperture imaging (ACAI) as a replacement system. Coded aperture imaging (CAI) has been used in both the astronomical and medical communities for years due to its ability to image light at short wavelengths and thus replacing conventional lenses. Where CAI is limited, researchers have discovered that adaptive coded …

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Enhancing The Ns-2 Network Simulator For Near Real-Time Control Feedback And Distributed Simulation Breaks, John S. Weir Mar 2009

Enhancing The Ns-2 Network Simulator For Near Real-Time Control Feedback And Distributed Simulation Breaks, John S. Weir

Theses and Dissertations

A network simulator coupled with a visualization package enables the human visual system to analyze the results of network modeling as a supplement to analytical data analysis. This research takes the next step in network simulator and visualization suite interaction. A mediator (or run-time infrastructure (RTI) in the literature) provides researchers the potential to interact with a simulation as it executes. Utilizing TCP/IP sockets, the mediator has the capability to connect multiple visualization packages to a single simulation. This new tool allows researchers to change simulation parameters on the y without restarting the network simulation.

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An Analysis Of Construction Contractor Performance Evaluation System, Rebecca S. Brown Mar 2009

An Analysis Of Construction Contractor Performance Evaluation System, Rebecca S. Brown

Theses and Dissertations

A rigorous system for rating construction contractor performance does not exist for the USAF as identified by the Air Force Civil Engineer (USAF CE), Major General Del Eulberg (Eulberg, 2007). The United States Army Corp of Engineers (USACE) uses DD Form 2626 for contractor performance evaluation and contractor selection. The objective of this research is to strengthen the USAF contractor rating system by exploring USACE‘s use of DD Form 2626. Using data from DD Form 2626, statistical analysis was conducted to determine if the measured performance sub-items reflect their respective performance elements, whether the resulting performance elements relate to the …

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Evaluation Of Performance Of A Maximum Likelihood Estimator For Tracking Purposes In The Presence Of Speckle Noise, Adrian Brett Monz Mar 2009

Evaluation Of Performance Of A Maximum Likelihood Estimator For Tracking Purposes In The Presence Of Speckle Noise, Adrian Brett Monz

Theses and Dissertations

In many cases, optical tracking systems do not have cooperative beacons avail- able. This is particularly true for the case involving tracking a laser illuminated target such as a missile seeker head, where the object of interest is an extended source. Furthermore the extended source is often observed in the presence of noise such as shot and speckle noise as well as atmospheric turbulence which further degrades the signal. This research effort presents the evaluation of an existing algorithm based on the maximum-likelihood technique for tilt estimation in the presence of extended sources and speckle noise, with particular application to …

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Modernizing A Preventive Maintenance Strategy For Facility And Infrastructure Maintenance, Ross E. Dotzlaf Mar 2009

Modernizing A Preventive Maintenance Strategy For Facility And Infrastructure Maintenance, Ross E. Dotzlaf

Theses and Dissertations

Preventive maintenance (PM) is defined as regularly scheduled maintenance actions based on average failure rates. A properly implemented PM strategy can provide many benefits to an organization in terms of extending equipment life, optimizing resource expenditures, and balancing work schedules. Periodic evaluation of a PM strategy can help identify ways to improve efficiencies and maximize effectiveness. This research effort was accomplished by performing a case study of the United States Air Force’s infrastructure and facility PM program known as the Recurring Work Program (RWP). The methodology consisted of two phases. The first phase, intended to develop an understanding of the …

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Stochastic Spatio-Temporal Uncertainty In Gis-Based Water Quality Modeling Of The Land Water Interface, Ahmad Mohamad Salah Feb 2009

Stochastic Spatio-Temporal Uncertainty In Gis-Based Water Quality Modeling Of The Land Water Interface, Ahmad Mohamad Salah

Theses and Dissertations

Integrated water resources management has been used for decades in various formats. The limited resources and the ever growing population keep imposing pressure on decision makers to better-, and reliably, manage the available waters. On the other hand, the continuous development in computing and modeling power has helped modelers and decision makers considerably. To use these models, assumptions have to be made to fill in the gaps of missing data and to approximate the current conditions. The type and amount of information available can also be used to help select the best model from the currently available models. Advances in …

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A Mems Multi-Cantilever Variable Capacitor On Metamaterial, Luke A. Rederus Feb 2009

A Mems Multi-Cantilever Variable Capacitor On Metamaterial, Luke A. Rederus

Theses and Dissertations

Negative refractive index materials are an example of metamaterials that are becoming increasingly popular. Research into these metamaterials could possibly be the first steps toward bending electromagnetic radiation (i.e., microwaves, light, etc.) around an object or person. Split ring resonators (SRR) are classified as metamaterials that create an artificial magnetic response from materials with no inherent magnetic properties. Once fabricated, an SRR has a specific resonant frequency due to its permanent geometry. This research introduces a new concept of using a variable capacitive micro- electro-mechanical system (MEMS) device located at the gap of an SRR to mechanically alter the capacitance …

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Power Generation By Harvesting Ambient Energy With A Micro-Electromagnetic Generator, James H. Shields Feb 2009

Power Generation By Harvesting Ambient Energy With A Micro-Electromagnetic Generator, James H. Shields

Theses and Dissertations

This thesis investigated the potential power output of a micro-electromagnetic generator fabricated using typical microfabrication materials and techniques. The design was based on a desire to free bio-implanted or remote electronic devices from batteries and their finite power supplies. A micro-electromagnetic generator could harvest energy from the ambient environment and power such devices indefinitely. Designs for the stator coil and rotor magnet components of the generator were optimized to produce maximum current density based upon electromagnetic theory. The relative orientation of the coil to the rotor and material selection for each component were considered. Coils were fabricated using low-resistance gold. …

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Communication Free Robot Swarming, Zachary C. Gray Feb 2009

Communication Free Robot Swarming, Zachary C. Gray

Theses and Dissertations

As the military use of unmanned aerial vehicles increases, a growing need for novel strategies to control these systems exists. One such method for controlling many unmanned aerial vehicles simultaneously is the through the use of swarm algorithms. This research explores a swarm robotic algorithm developed by Kadrovach implemented on Pioneer Robots in a real-world environment. An adaptation of his visual sensor is implemented using stereo vision as the primary method of sensing the environment. The swarm members are prohibited from explicitly communicating other than passively through the environment. The resulting implementation produces a communication free swarming algorithm. The algorithm …

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Chip To Chip Optical Interconnection Using Mems Mirrors, Tod V. Laurvick Feb 2009

Chip To Chip Optical Interconnection Using Mems Mirrors, Tod V. Laurvick

Theses and Dissertations

This experiment explores the use of MEMS mirrors to direct subsurface optical signals to another device and reception of those signals for use in chip to chip communications. Devices were built in PolyMUMPs to control horizontal and vertical beam direction and tilting in the outgoing signal and MEMS beam splitters for the incoming signal. Several elements of the outgoing beam path were successful and those which needed improvement indicate a high probability of success with limited trials needed and currently successful design elements could still be improved within the scope of PolyMUMPs. The incoming beam path elements were not successful …

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Automated Virtual Machine Introspection For Host-Based Intrusion Detection, Brett A. Pagel Feb 2009

Automated Virtual Machine Introspection For Host-Based Intrusion Detection, Brett A. Pagel

Theses and Dissertations

This thesis examines techniques to automate configuration of an intrusion detection system utilizing hardware-assisted virtualization. These techniques are used to detect the version of a running guest operating system, automatically configure version-specific operating system information needed by the introspection library, and to locate and monitor important operating system data structures. This research simplifies introspection library configuration and is a step toward operating system independent introspection. An operating system detection algorithm and Windows virtual machine system service dispatch table monitor are implemented using the Xen hypervisor and a modified version of the XenAccess library. All detection and monitoring is implemented from …

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Adaptive Control Of Woofer-Tweeter Adaptive Optics, Jimmie J. Perez Feb 2009

Adaptive Control Of Woofer-Tweeter Adaptive Optics, Jimmie J. Perez

Theses and Dissertations

Adaptive optics applies advanced sensing and control to improve the ability of optical systems to collect images through a turbulent atmosphere. The results of this research effort demonstrate that the combination of two recent approaches improves the performance of adaptive optics in directed energy and laser communication scenarios. The first approach is adaptive control, which offers improved performance over fixed-gain controllers in the presence of rapidly changing turbulence. The second approach incorporated into the study is a dual-mirror system. The two mirrors are a high-bandwidth, low-actuator-stroke (tweeter) mirror and a low-bandwidth, large actuator-stroke (woofer) mirror. The woofer-tweeter combination allows for …

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Automated Knowledge Generation With Persistent Surveillance Video, Daniel T. Schmitt Feb 2009

Automated Knowledge Generation With Persistent Surveillance Video, Daniel T. Schmitt

Theses and Dissertations

The Air Force has increasingly invested in persistent surveillance platforms gathering a large amount of surveillance video. Ordinarily, intelligence analysts watch the video to determine if suspicious activities are occurring. This approach to video analysis can be a very time and manpower intensive process. Instead, this thesis proposes that by using tracks generated from persistent video, we can build a model to detect events for an intelligence analyst. The event that we chose to detect was a suspicious surveillance activity known as a casing event. To test our model we used Global Positioning System (GPS) tracks generated from vehicles driving …

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Real-Time Carrier Frequency Estimation Using Disjoint Pilot Symbol Blocks, Joseph M. Palmer Feb 2009

Real-Time Carrier Frequency Estimation Using Disjoint Pilot Symbol Blocks, Joseph M. Palmer

Theses and Dissertations

Three new and efficient carrier frequency offset estimators are created for the case of disjoint pilot symbol blocks. The estimators are efficient in both a statistical sense and a computational sense. They are formulated to reduce computational cost for use in real-time applications, such as FPGA (field programmable gate array) devices. A reduced cost maximum likelihood (ML) frequency estimator is described. It is a generalization of the approximate ML estimator for a single block of pilot symbols. A number of recent ML estimation techniques are integrated with the purpose of reducing the computational cost while preserving estimation performance. The estimator …

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Subjective Audio Quality Over A Secure Ieee 802.11n Draft 2.0 Wireless Local Area Network, Benjamin W. Ramsey Feb 2009

Subjective Audio Quality Over A Secure Ieee 802.11n Draft 2.0 Wireless Local Area Network, Benjamin W. Ramsey

Theses and Dissertations

This thesis investigates the quality of audio generated by a G.711 codec and transmission over an IEEE 802.11n draft 2.0 wireless local area network (WLAN). Decline in audio quality due to additional calls or by securing the WLAN with transport mode Internet Protocol Security (IPsec) is quantified. Audio quality over an IEEE 802.11n draft 2.0 WLAN is also compared to that of IEEE 802.11b and IEEE 802.11g WLANs under the same conditions. Audio quality is evaluated by following International Telecommunication Union Telecommunication Standardization Sector (ITU-T) Recommendation P.800, where human subjects rate audio clips recorded during various WLAN configurations. The Mean …

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Position Concordant - Haptic Mouse, Ravi Rastogi Feb 2009

Position Concordant - Haptic Mouse, Ravi Rastogi

Theses and Dissertations

Haptic mice, computer mice modified to have a tactile display, have been developed to enable access to computer graphics by individuals who are blind or visually impaired. Although these haptic mice are potentially very helpful and have been frequently used by the research community, there are some fundamental problems with the mouse, limiting its acceptance. In this paper we have identified the problems and have suggested solutions using one haptic mouse, the VT Player. We found that our modified VT Player showed significant improvement both in terms of the odds of obtaining a correct responses and the time to perform …

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A New Model For Aqueous Electrolyte Solutions Near The Critical Point Of Water Incorporating Aqueous Reaction Equilibria, Craig J. Peterson Feb 2009

A New Model For Aqueous Electrolyte Solutions Near The Critical Point Of Water Incorporating Aqueous Reaction Equilibria, Craig J. Peterson

Theses and Dissertations

Aqueous electrolyte solutions at temperature and pressure conditions near the critical point of water are difficult to describe using traditional equations of state based upon the excess Gibbs energy. Models based upon the residual Helmholtz energy have proven more effective. Anderko and Pitzer1 developed a residual Helmholtz energy model (AP) for aqueous electrolyte solutions in which the electrolyte is assumed to be fully associated. The model has been effectively used in describing densities and vapor-liquid equilibria for simple electrolyte systems. The model is less effective for describing enthalpic properties such as heats of dilution. Oscarson and coworkers2, 3 modified the …

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An Fpga-Based System For Tracking Digital Information Transmitted Via Peer-To-Peer Protocols, Karl R. Schrader Feb 2009

An Fpga-Based System For Tracking Digital Information Transmitted Via Peer-To-Peer Protocols, Karl R. Schrader

Theses and Dissertations

This thesis addresses the problem of identifying and tracking digital information that is shared using peer-to-peer file transfer and Voice over IP (VoIP) protocols. The goal of the research is to develop a system for detecting and tracking the illicit dissemination of sensitive government information using file sharing applications within a target network, and tracking terrorist cells or criminal organizations that are covertly communicating using VoIP applications. A digital forensic tool is developed using an FPGA-based embedded software application. The tool is designed to process file transfers using the BitTorrent peer-to-peer protocol and VoIP phone calls made using the Session …

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Optical And Electrical Properties Of Compound And Transition Metal Doped Compound Semiconductor Nanowires, Sivakumar Ramanathan Feb 2009

Optical And Electrical Properties Of Compound And Transition Metal Doped Compound Semiconductor Nanowires, Sivakumar Ramanathan

Theses and Dissertations

Nanotechnology is the science and engineering of creating functional materials by precise control of matter at nanometer (nm) length scale and exploring novel properties at that scale. It is vital to understand the quantum mechanical phenomena manifested at nanometer scale dimensions since that will enable us to precisely engineer quantum mechanical properties to realize novel device functionalities. This dissertation investigates optical and electronic properties of compound and transition metal doped compound semiconductor nanowires with a view to exploiting them for a wide range of applications in semiconductor electronic and optical devices. In this dissertation work, basic concepts of optical and …

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Decentralized Estimation Using Information Consensus Filters With A Multi-Static Uav Radar Tracking System, David W. Casbeer Feb 2009

Decentralized Estimation Using Information Consensus Filters With A Multi-Static Uav Radar Tracking System, David W. Casbeer

Theses and Dissertations

This dissertation lays out a multi-static radar system with mobile receivers. The transmitter is at a known location emitting a radar signal that bounces off a target. The echo is received by a team of UAVs that are capable of estimating both time-delay and Doppler from the received signal. Several methods for controlling the movement of mobile sensor platforms are presented to improve target tracking performance. Two optimization criteria are derived for the problem, both of which require some type of search procedure to find the desired solution. Simulations are used to show the benefit of using closed-loop sensor control …

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