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Air Force Institute of Technology

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Articles 1291 - 1320 of 2678

Full-Text Articles in Physical Sciences and Mathematics

Three Dimensional Positron Annihilation Momentum Measurement Technique (3dpamm) Applied To Measure Oxygen-Atom Defects In 6h Silicon Carbide, Christopher S. Williams Mar 2010

Three Dimensional Positron Annihilation Momentum Measurement Technique (3dpamm) Applied To Measure Oxygen-Atom Defects In 6h Silicon Carbide, Christopher S. Williams

Theses and Dissertations

A three-dimensional Positron Annihilation Spectroscopy System (3DPASS) capable to simultaneously measure three-dimensional electron-positron (e--e+) momentum densities measuring photons derived from e--e+ annihilation events was designed and characterized. 3DPASS simultaneously collects a single data set of correlated energies and positions for two coincident annihilation photons using solid-state double-sided strip detectors (DSSD). Positions of photons were determined using an interpolation method which measures a figure-of-merit proportional to the areas of transient charges induced on both charge collection strips directly adjacent to the charge collection strips interacting with the annihilation photons. The subpixel resolution was measured for both double-sided strip detectors (DSSD) and …

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Development Of A Methodology For Customizing Insider Threat Auditing On A Linux Operating System, William T. Bai Mar 2010

Development Of A Methodology For Customizing Insider Threat Auditing On A Linux Operating System, William T. Bai

Theses and Dissertations

Insider threats can pose a great risk to organizations and by their very nature are difficult to protect against. Auditing and system logging are capabilities present in most operating systems and can be used for detecting insider activity. However, current auditing methods are typically applied in a haphazard way, if at all, and are not conducive to contributing to an effective insider threat security policy. This research develops a methodology for designing a customized auditing and logging template for a Linux operating system. An intent-based insider threat risk assessment methodology is presented to create use case scenarios tailored to address …

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Coalition Formation Under Uncertainty, Daylond J. Hooper Mar 2010

Coalition Formation Under Uncertainty, Daylond J. Hooper

Theses and Dissertations

Many multiagent systems require allocation of agents to tasks in order to ensure successful task execution. Most systems that perform this allocation assume that the quantity of agents needed for a task is known beforehand. Coalition formation approaches relax this assumption, allowing multiple agents to be dynamically assigned. Unfortunately, many current approaches to coalition formation lack provisions for uncertainty. This prevents application of coalition formation techniques to complex domains, such as real-world robotic systems and agent domains where full state knowledge is not available. Those that do handle uncertainty have no ability to handle dynamic addition or removal of agents …

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Rubidium Recycling In A High Intensity Short Duration Pulsed Alkali Laser, Wooddy S. Miller Mar 2010

Rubidium Recycling In A High Intensity Short Duration Pulsed Alkali Laser, Wooddy S. Miller

Theses and Dissertations

Laser induced fluorescence was used to study how pump pulse duration and alkali recycle time effects maximum power output in a Diode Pumped Alkali Laser (DPAL) system. A high intensity short pulsed pump source was used to excited rubidium atoms inside a DPAL-type laser. The maximum output power of the laser showed a strong dependence upon the temporal width of the pump pulse in addition to the input pump intensity. A linear relationship was observed between the maximum output power and the pulse width due to the effective lifetime of the excited state, defined as the time it takes for …

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Afm-Patterned 2-D Thin-Film Photonic Crystal Analyzed By Complete Angle Scatter, Nicholas C. Herr Mar 2010

Afm-Patterned 2-D Thin-Film Photonic Crystal Analyzed By Complete Angle Scatter, Nicholas C. Herr

Theses and Dissertations

The purpose of this research was to use an atomic force microscope (AFM) to generate a 2-D square array of sub-wavelength surface features from a single material over a region large enough to permit optical characterization. This work is an extension of previous AFIT nano-patterning work and is in response to the small subunit sizes demanded for the production of optical metamaterials and photonic crystals. A diamond nano-indentation AFM probe was used to produce a 325-μm by 200-μm array of indentations in a 120-nm thick polystyrene film deposited on silicon. Indentation spacing of 400 nm produced well-defined surface features with …

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Evaluation Of Alternative Technologies To Supply Drinking Water To Marines In Forward Deployed Locations, Derek R. George Mar 2010

Evaluation Of Alternative Technologies To Supply Drinking Water To Marines In Forward Deployed Locations, Derek R. George

Theses and Dissertations

With recent increases, there are approximately 20,000 Marines deployed in the Helmand Province of Afghanistan. The cost of delivering bottled water to the troops is rapidly becoming unsustainable and convoys delivering bottled water are vulnerable to Improvised Explosive Devices (IEDs). Currently, raw water from indigenous sources, which has chemical and microbiological contaminants, is treated with reverse osmosis (RO), but only used for hygiene, with bottled water used for drinking. Due to the economic costs and risks to life of providing bottled water, decision-makers need to evaluate technology alternatives to treat raw water to supply safe drinking water. In this study, …

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Calculation Of Collisional Cross Sections For The ²P3/2 > ²P1/2 Transition In Alkali-Noble Gas Systems, Samuel D. Butler Mar 2010

Calculation Of Collisional Cross Sections For The ²P3/2 > ²P1/2 Transition In Alkali-Noble Gas Systems, Samuel D. Butler

Theses and Dissertations

Collisional cross sections were calculated as a function of energy for two coupled one dimensional, spherically symmetric potentials. The Split Operator Method was used to propagate an initial Moller state, chosen to be a Gaussian in the asymptotic limit, through a potential. The correlation between the wave packet and Moller final state was calculated at each time step. Using the Channel Packet Method, the correlation function was used to obtain scattering matrix elements. From scattering matrix elements for several different effective potential values and using the Method of Partial Waves, the collisional cross section is calculated for the transition from …

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Augmenting Latent Dirichlet Allocation And Rank Threshold Detection With Ontologies, Laura A. Isaly Mar 2010

Augmenting Latent Dirichlet Allocation And Rank Threshold Detection With Ontologies, Laura A. Isaly

Theses and Dissertations

In an ever-increasing data rich environment, actionable information must be extracted, filtered, and correlated from massive amounts of disparate often free text sources. The usefulness of the retrieved information depends on how we accomplish these steps and present the most relevant information to the analyst. One method for extracting information from free text is Latent Dirichlet Allocation (LDA), a document categorization technique to classify documents into cohesive topics. Although LDA accounts for some implicit relationships such as synonymy (same meaning) it often ignores other semantic relationships such as polysemy (different meanings), hyponym (subordinate), meronym (part of), and troponomys (manner). To …

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Digital Delay Device, Guna Seetharaman, Paul E. Kladitis Mar 2010

Digital Delay Device, Guna Seetharaman, Paul E. Kladitis

AFIT Patents

A digitally controlled optical delay apparatus providing optical signal delays electrically selectable in the picosecond to nanosecond range by way of selectable signal path lengths. Path lengths are incremented in physical length and path delay time according to digital ratios. The delay element includes micro-miniature path changing mirrors controlled in path length selecting positioning by input signals of logic level magnitude. Fiber optic coupling of signals to and from the delay element and a combination of fixed position and movable mirror included optical signal path lengths are included.

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An Fpga-Based System For Tracking Digital Information Transmitted Via Peer-To-Peer Protocols, Karl R. Schrader, Barry E. Mullins, Gilbert L. Peterson, Robert F. Mills Jan 2010

An Fpga-Based System For Tracking Digital Information Transmitted Via Peer-To-Peer Protocols, Karl R. Schrader, Barry E. Mullins, Gilbert L. Peterson, Robert F. Mills

Faculty Publications

This paper presents a Field Programmable Gate Array (FPGA)-based tool designed to process file transfers using the BitTorrent Peer-to-Peer (P2P) protocol and VoIP phone calls made using the Session Initiation Protocol (SIP). The tool searches selected control messages in real time and compares the unique identifier of the shared file or phone number against a list of known contraband files or phone numbers. Results show the FPGA tool processes P2P packets of interest 92% faster than a software-only configuration and is 97.6% accurate at capturing and processing messages at a traffic load of 89.6 Mbps.

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Analysis Of Expedient Field Decontamination Methods For The Xmx/2l-Mil High-Volume Aerosol Sampler, Brandon C. Laroche Dec 2009

Analysis Of Expedient Field Decontamination Methods For The Xmx/2l-Mil High-Volume Aerosol Sampler, Brandon C. Laroche

Theses and Dissertations

The XMX/2L-MIL is a high volume air sampler used by the Air Force Bioenvironmental Engineering community to collect biological aerosols. Without a verified decontamination technique, however, the XMX cannot be used effectively. The objective of this study was to evaluate several proposed methods for expedient field decontamination of the XMX. This study centered on the inactivation of Bacillus atrophaeus spores and vegetative Erwinia herbicola organisms from the XMX inner canister. The goals in this investigation were twofold: 1) to verify the antimicrobial efficacy of a 10% bleach solution and 2) to determine if wiping the components with a bleach-soaked paper …

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Large-Scale Distributed Coalition Formation, Daniel R. Karrels Dec 2009

Large-Scale Distributed Coalition Formation, Daniel R. Karrels

Theses and Dissertations

The CyberCraft project is an effort to construct a large scale Distributed Multi-Agent System (DMAS) to provide autonomous Cyberspace defense and mission assurance for the DoD. It employs a small but flexible agent structure that is dynamically reconfigurable to accommodate new tasks and policies. This document describes research into developing protocols and algorithms to ensure continued mission execution in a system of one million or more agents, focusing on protocols for coalition formation and Command and Control. It begins by building large-scale routing algorithms for a Hierarchical Peer to Peer structured overlay network, called Resource-Clustered Chord (RC-Chord). RC-Chord introduces the …

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Midwave Infrared Imaging Fourier Transform Spectrometry Of Combustion Plumes, Kenneth C. Bradley Dec 2009

Midwave Infrared Imaging Fourier Transform Spectrometry Of Combustion Plumes, Kenneth C. Bradley

Theses and Dissertations

A midwave infrared (MWIR) imaging Fourier transform spectrometer (IFTS) was used to successfully capture and analyze hyperspectral imagery of combustion plumes. Jet engine exhaust data from a small turbojet engine burning diesel fuel at a flow rate of 300 cm3/min was collected at 1 cm−1 resolution from a side-plume vantage point on a 200x64 pixel window at a range of 11.2 meters. Spectral features of water, CO, and CO2 were present, and showed spatial variability within the plume structure. An array of thermocouple probes was positioned within the plume to aid in temperature analysis. A single-temperature …

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Structured P2p Technologies For Distributed Command And Control, Daniel R. Karrels, Gilbert L. Peterson, Barry E. Mullins Dec 2009

Structured P2p Technologies For Distributed Command And Control, Daniel R. Karrels, Gilbert L. Peterson, Barry E. Mullins

Faculty Publications

The utility of Peer-to-Peer (P2P) systems extends far beyond traditional file sharing. This paper provides an overview of how P2P systems are capable of providing robust command and control for Distributed Multi-Agent Systems (DMASs). Specifically, this article presents the evolution of P2P architectures to date by discussing supporting technologies and applicability of each generation of P2P systems. It provides a detailed survey of fundamental design approaches found in modern large-scale P2P systems highlighting design considerations for building and deploying scalable P2P applications. The survey includes unstructured P2P systems, content retrieval systems, communications structured P2P systems, flat structured P2P systems and …

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Rc-Chord: Resource Clustering In A Large-Scale Hierarchical Peer-To-Peer System, Daniel R. Karrels, Gilbert L. Peterson, Barry E. Mullins Oct 2009

Rc-Chord: Resource Clustering In A Large-Scale Hierarchical Peer-To-Peer System, Daniel R. Karrels, Gilbert L. Peterson, Barry E. Mullins

Faculty Publications

Conducting data fusion and Command and Control (C2) in large-scale systems requires more than the presently available Peer-to-Peer (P2P) technologies provide. Resource Clustered Chord (RC-Chord) is an extension to the Chord protocol that incorporates elements of a hierarchical peer-to-peer architecture to facilitate coalition formation algorithms in large-scale systems. Each cluster in this hierarchy represents a particular resource available for allocation, and RC-Chord provides the capabilities to locate agents of a particular resource. This approach improves upon other strategies by including support for abundant resources, or those resources that most or all agents in the system possess. This scenario exists in …

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Dynamic Coalition Formation Under Uncertainty, Daylon J. Hooper, Gilbert L. Peterson, Brett J. Borghetti Oct 2009

Dynamic Coalition Formation Under Uncertainty, Daylon J. Hooper, Gilbert L. Peterson, Brett J. Borghetti

Faculty Publications

Coalition formation algorithms are generally not applicable to real-world robotic collectives since they lack mechanisms to handle uncertainty. Those mechanisms that do address uncertainty either deflect it by soliciting information from others or apply reinforcement learning to select an agent type from within a set. This paper presents a coalition formation mechanism that directly addresses uncertainty while allowing the agent types to fall outside of a known set. The agent types are captured through a novel agent modeling technique that handles uncertainty through a belief-based evaluation mechanism. This technique allows for uncertainty in environmental data, agent type, coalition value, and …

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Application Of Dual-Tree Complex Wavelet Transforms To Burst Detection And Rf Fingerprint Classification, Randall W. Klein Aug 2009

Application Of Dual-Tree Complex Wavelet Transforms To Burst Detection And Rf Fingerprint Classification, Randall W. Klein

Theses and Dissertations

This work addresses various Open Systems Interconnection (OSI) Physical (PHY) layer mechanisms to extract and exploit RF waveform features (”fingerprints”) that are inherently unique to specific devices and that may be used to provide hardware specific identification (manufacturer, model, and/or serial number). This is addressed by applying a Dual-Tree Complex Wavelet Transform (DT-CWT) to improve burst detection and RF fingerprint classification. A ”Denoised VT” technique is introduced to improve performance at lower SNRs, with denoising implemented using a DT-CWT decomposition prior to Traditional VT processing. A newly developed Wavelet Domain (WD) fingerprinting technique is presented using statistical WD fingerprints with …

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A Trust-Based Multiagent System, Richard S. Seymour, Gilbert L. Peterson Aug 2009

A Trust-Based Multiagent System, Richard S. Seymour, Gilbert L. Peterson

Faculty Publications

Cooperative agent systems often do not account for sneaky agents who are willing to cooperate when the stakes are low and take selfish, greedy actions when the rewards rise. Trust modeling often focuses on identifying the appropriate trust level for the other agents in the environment and then using these levels to determine how to interact with each agent. Adding trust to an interactive partially observable Markov decision process (I-POMDP) allows trust levels to be continuously monitored and corrected enabling agents to make better decisions. The addition of trust modeling increases the decision process calculations, and solves more complex trust …

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Unified Behavior Framework For Reactive Robot Control, Brian G. Woolley, Gilbert L. Peterson Jul 2009

Unified Behavior Framework For Reactive Robot Control, Brian G. Woolley, Gilbert L. Peterson

Faculty Publications

Behavior-based systems form the basis of autonomous control for many robots. In this article, we demonstrate that a single software framework can be used to represent many existing behavior based approaches. The unified behavior framework presented, incorporates the critical ideas and concepts of the existing reactive controllers. Additionally, the modular design of the behavior framework: (1) simplifies development and testing; (2) promotes the reuse of code; (3) supports designs that scale easily into large hierarchies while restricting code complexity; and (4) allows the behavior based system developer the freedom to use the behavior system they feel will function the best. …

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Effect Of Advanced Synthetically Enhanced Detector Resolution Algorithm On Specificity And Sensitivity Of Portable High Purity Germanium Gamma Detector Spectra, Latosha M. Bell Jun 2009

Effect Of Advanced Synthetically Enhanced Detector Resolution Algorithm On Specificity And Sensitivity Of Portable High Purity Germanium Gamma Detector Spectra, Latosha M. Bell

Theses and Dissertations

The ability to identify special nuclear material is one of the necessary prevention mechanisms for preventing proliferation of special nuclear materials. Additionally, if a nuclear event were to occur, information about the nuclear material used may be extracted from gamma spectra, provided it is obtained quickly and accurately. This can be made possible with the use of the exceptional resolution of the HPGe detector. This experiment applied the Advanced Synthetically Enhanced Detector Resolution Algorithm (ASEDRA) to a portable HPGe detector's spectra, to investigate whether improvements in specificity and sensitivity can be obtained. This method has been used to improve performance …

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An Efficient And Effective Implementation Of The Trust System For Power Grid Compartmentalization, Juan M. Carlos Gonzalez Jun 2009

An Efficient And Effective Implementation Of The Trust System For Power Grid Compartmentalization, Juan M. Carlos Gonzalez

Theses and Dissertations

As utility companies develop and incorporate new technologies, such as moving to utility Internet technology based architecture and standard; it is crucial that we do so with history in mind. We know that traditional utility protection and control systems were not designed with security in their top priorities. This presents a danger in an environment where near real-time responses are required to ensure safe operations. As a consequence, system security becomes a burden to the system rather than necessary protection. Unfortunately, technology implementation is not the only concern. The number of utility privately-owned companies has multiplied as the market has …

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Developing Systems For Cyber Situational Awareness, James. S. Okolica, J. Todd Mcdonald, Gilbert L. Peterson, Robert F. Mills, Michael W. Haas Jun 2009

Developing Systems For Cyber Situational Awareness, James. S. Okolica, J. Todd Mcdonald, Gilbert L. Peterson, Robert F. Mills, Michael W. Haas

Faculty Publications

In both military and commercial settings, the awareness of Cyber attacks and the effect of those attacks on the mission space of an organization has become a targeted information goal for leaders and commanders at all levels. We present in this paper a defining framework to understand situational awareness (SA)—especially as it pertains to the Cyber domain—and propose a methodology for populating the cognitive domain model for this realm based on adversarial knowledge involved with Cyber attacks. We conclude with considerations for developing Cyber SA systems of the future.

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Frequency Diversity For Improving Synthetic Aperture Radar Imaging, Jawad L. Farooq Mar 2009

Frequency Diversity For Improving Synthetic Aperture Radar Imaging, Jawad L. Farooq

Theses and Dissertations

In this work, a novel theoretical framework is presented for using recent advances in frequency diversity arrays (FDAs). Unlike a conventional array, the FDA simultaneously transmits a unique frequency from each element in the array. As a result, special time and space properties of the radiation pattern are exploited to improve cross-range resolution. The idealized FDA radiation pattern is compared with and validated against a full-wave electromagnetic solver, and it is shown that the conventional array is a special case of the FDA. A new signal model, based on the FDA, is used to simulate SAR imagery of ideal point …

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Determining The Orbit Locations Of Turkish Airborne Early Warning And Control Aircraft Over The Turkish Air Space, Nebi Sarikaya Mar 2009

Determining The Orbit Locations Of Turkish Airborne Early Warning And Control Aircraft Over The Turkish Air Space, Nebi Sarikaya

Theses and Dissertations

The technology improvement affects the military needs of individual countries. The new doctrine of defense for many countries emphasizes detecting threats as far away as you can from your homeland. Today, the military uses both ground RADAR and Airborne Early Warning and Control (AEW&C) Aircraft. AEW&C aircraft has become vital to detect low altitude threats that a ground RADAR cannot detect because of obstacles on the earth. Turkey has ordered four AEW&C aircraft for her air defense system because of the lack of complete coverage by ground RADAR. This research provides optimal orbit locations that can be updated according to …

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Social Networking Website Users And Privacy Concerns: A Mixed Methods Investigation, Stephanie J. Mills Mar 2009

Social Networking Website Users And Privacy Concerns: A Mixed Methods Investigation, Stephanie J. Mills

Theses and Dissertations

Social networking websites are the fastest growing entity on the Internet. Users of social networking websites post personal information and pictures on these websites. Privacy and social networking websites has been previously studied, however, since those studies were conducted the rules for those websites have changed dramatically. A mixed methods approach was used in this study to examine what privacy concerns users of social networking websites have, whether it’s regarding information on their accounts or the pictures they have posted. This study also considered if there were common personality traits present in people with those concerns. A comparison of user …

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Exploitation Of Geographic Information Systems For Vehicular Destination Prediction, Richard T. Muster Mar 2009

Exploitation Of Geographic Information Systems For Vehicular Destination Prediction, Richard T. Muster

Theses and Dissertations

Much of the recent successes in the Iraqi theater have been achieved with the aid of technology so advanced that celebrated journalist Bob Woodward recently compared it to the Manhattan Project of WWII. Intelligence, Surveillance, and Reconnaissance (ISR) platforms have emerged as the rising star of Air Force operational capabilities as they are enablers in the quest to track and disrupt terrorist and insurgent forces. This thesis argues that ISR systems have been severely under-exploited. The proposals herein seek to improve the machine-human interface of current ISR systems such that a predictive battle-space awareness may be achieved, leading to shorter …

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Bit-Error-Rate-Minimizing Channel Shortening Using Post-Feq Diversity Combining And A Genetic Algorithm, Gokhan Altin Mar 2009

Bit-Error-Rate-Minimizing Channel Shortening Using Post-Feq Diversity Combining And A Genetic Algorithm, Gokhan Altin

Theses and Dissertations

In advanced wireline or wireless communication systems, i.e., DSL, IEEE 802.11a/g, HIPERLAN/2, etc., a cyclic prefix which is proportional to the channel impulse response is needed to append a multicarrier modulation (MCM) frame for operating the MCM accurately. This prefix is used to combat inter symbol interference (ISI). In some cases, the channel impulse response can be longer than the cyclic prefix (CP). One of the most useful techniques to mitigate this problem is reuse of a Channel Shortening Equalizer (CSE) as a linear preprocessor before the MCM receiver in order to shorten the effective channel length. Channel shortening filter …

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Dynamic Network Formation Using Ant Colony Optimization, Steven C. Oimoen Mar 2009

Dynamic Network Formation Using Ant Colony Optimization, Steven C. Oimoen

Theses and Dissertations

Military and industry are moving toward every device being network enabled and connected for reliable availability of communication and information. To make this type of system a reality, the devices must be capable of forming a network topology on their own in a dynamic environment to ensure that the correct information reaches a desired location and on-time. This research presents three contributions for solving highly dynamic (i.e. drastic change within the network) Multi-commodity Capacitated Network Design Problems (MCNDPs) resulting in a distributed multi-agent network design algorithm. The first contribution incorporates an Ant Colony Optimization (ACO) algorithm Ant Colony System (ACS) …

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A Framework For Analyzing Biometric Template Aging And Renewal Prediction, John W. Carls Mar 2009

A Framework For Analyzing Biometric Template Aging And Renewal Prediction, John W. Carls

Theses and Dissertations

Biometric technology and systems are modernizing identity capabilities. With maturing biometrics in full, rapid development, a higher accuracy of identity verification is required. An improvement to the security of biometric-based verification systems is provided through higher accuracy; ultimately reducing fraud, theft, and loss of resources from unauthorized personnel. With trivial biometric systems, a higher acceptance threshold to obtain higher accuracy rates increase false rejection rates and user unacceptability. However, maintaining the higher accuracy rate enhances the security of the system. An area of biometrics with a paucity of research is template aging and renewal prediction, specifically in regards to facial …

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Forecasting Usaf Jp-8 Fuel Needs, Omer Saglam Mar 2009

Forecasting Usaf Jp-8 Fuel Needs, Omer Saglam

Theses and Dissertations

Oil is still one of the strategic energy resources for both the U.S. and the USAF today. Accurate oil prediction is important for the U.S. in order to improve the national strategy and the related budget concerns. Today, the U.S. is roughly importing 58% of its petroleum products. Moreover, in Fiscal Year (FY) 2007 the USAF total energy costs exceeded $6.9 billion. Aviation fuel accounted for approximately 81% of the total AF energy costs. Fluctuations in oil prices have huge impacts on the USAF’s JP-8 budgetary calculations. In order to handle this problem, the need for accurate forecasts arises. In …

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