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Articles 5701 - 5730 of 8341

Full-Text Articles in Physical Sciences and Mathematics

Role Of Members Of The Phosducin Gene Family In Protein Translation And Folding, Nana Sono-Koree Mar 2010

Role Of Members Of The Phosducin Gene Family In Protein Translation And Folding, Nana Sono-Koree

Theses and Dissertations

G proteins regulate various physiological processes by way of transducing a wide variety of signals ranging from hormonal to sensory stimuli. Malfunctions in G protein signaling lead to numerous diseases. G protein signaling begins with binding of a ligand to a G protein-coupled receptor resulting in a conformational change that leads to the exchange of a GDP for a GTP on G α. The GTP bound α subunit dissociates for its stable Gβγ dimer partner. G α-GTP and Gβγ control the activity of effector enzymes and ion channels that ultimately orchestrate the cellular response to stimulus. Current reports have shown …

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Testing Models Related To The Laramide Uplift Of The Uinta Mountains And Geologic Mapping Of The Jessen Butte 7.5 Minute Quadrangle, Dagget County, Utah And Sweetwater County, Wyoming, Coreen Hurst Mar 2010

Testing Models Related To The Laramide Uplift Of The Uinta Mountains And Geologic Mapping Of The Jessen Butte 7.5 Minute Quadrangle, Dagget County, Utah And Sweetwater County, Wyoming, Coreen Hurst

Theses and Dissertations

Geologic mapping of the Jessen Butte 7.5 minute quadrangle and the gathering of structural data throughout the quadrangle was used to determine the paleostress regime during the Laramide Orogeny along the north flank of the Uinta Mountains. The Henrys Fork thrust fault and the Uinta thrust fault are major north bounding faults and within the Jessen Butte quadrangle these faults transfer deformation from one to the other. The Jessen Butte thrust fault is a fault splay that splits off from the Henrys Fork thrust fault. Complex fold geometries were created by the interaction of the faults. Bedding plane orientation, mode …

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Maximizing Strike Planning Efficiency For A Given Class Of Targets, Necip Dirik Mar 2010

Maximizing Strike Planning Efficiency For A Given Class Of Targets, Necip Dirik

Theses and Dissertations

Strike planning is one of the fundamental tasks of the Turkish Air Force and involves assignment of strike aircraft to targets with a maximum level of efficiency. Therefore, planning an optimal strike plan based on the preferences of the decision maker is crucial. The efficiency of the strike plan in this research implies attacking the maximum number of targets while considering target priority and the desired level of damage on each target. Another objective is to minimize the cost of the plan. This research develops an exact model that maximizes the efficiency of the strike plan using LINGO with Excel …

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Planar Cat(K) Subspaces, Russell M. Ricks Mar 2010

Planar Cat(K) Subspaces, Russell M. Ricks

Theses and Dissertations

Let M_k^2 be the complete, simply connected, Riemannian 2-manifold of constant curvature k ± 0. Let E be a closed, simply connected subspace of M_k^2 with the property that every two points in E are connected by a rectifi able path in E. We show that E is CAT(k) under the induced path metric.

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Positron Annihilation Ratio Spectroscopy (Psars) Applied To Positronium Formation Studies, Robert C. Slaughter Mar 2010

Positron Annihilation Ratio Spectroscopy (Psars) Applied To Positronium Formation Studies, Robert C. Slaughter

Theses and Dissertations

A Positron Annihilation of Radiation Spectrometer (PsARS) was developed and characterized. PsARS spectroscopy as well as digital Positron Annihilation Lifetime Spectroscopy (PALS) was applied to measure positronium formation on gold nanoparticles deposited through an evaporative method onto a thin capillary tube. This gold coated capillary tube was designed to be used for positronium lifetime studies in local electric field experiments. High local electric fields can polarize a positron-electron pair, which may result in an extended lifetime of the positron. These fields may be created through the interaction of an external electric field with silver nanoparticles deposited onto the surface of …

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Mission Analysis And Design For Space Based Inter-Satellite Laser Power Beaming, Nicholas M. Keller Mar 2010

Mission Analysis And Design For Space Based Inter-Satellite Laser Power Beaming, Nicholas M. Keller

Theses and Dissertations

This research effort develops an interdisciplinary design tool to optimize an orbit for the purpose of wirelessly beaming power from the International Space Stations (ISS) Japanese Experimental Module Exposed Facility (JEM/EF) to a target satellite. For the purpose of this initiative, the target satellite will be referred to as FalconSAT6, a reference to the proposed follow-on satellite to the U.S. Air Force Academy’s (USAFA) FalconSAT5 program. The USAFA FalconSAT program provides cadets an opportunity to design, analyze, build, test and operate small satellites to conduct Department of Defense (DoD) space missions. The tool developed for this research is designed to …

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Visually Managing Ipsec, Peter J. Dell'accio Mar 2010

Visually Managing Ipsec, Peter J. Dell'accio

Theses and Dissertations

The United States Air Force relies heavily on computer networks to transmit vast amounts of information throughout its organizations and with agencies throughout the Department of Defense. The data take many forms, utilize different protocols, and originate from various platforms and applications. It is not practical to apply security measures specific to individual applications, platforms, and protocols. Internet Protocol Security (IPsec) is a set of protocols designed to secure data traveling over IP networks, including the Internet. By applying security at the network layer of communications, data packets can be secured regardless of what application generated the data or which …

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Codifying Information Assurance Controls For Department Of Defense (Dod) Supervisory Control And Data Acquisition (Scada) Systems (U), Eddie A. Mendezllovet Mar 2010

Codifying Information Assurance Controls For Department Of Defense (Dod) Supervisory Control And Data Acquisition (Scada) Systems (U), Eddie A. Mendezllovet

Theses and Dissertations

Protecting DoD critical infrastructure resources and Supervisory Control and Data Acquisition (SCADA) systems from cyber attacks is becoming an increasingly challenging task. DoD Information Assurance controls provide a sound framework to achieve an appropriate level of confidentiality, integrity, and availability. However, these controls have not been updated since 2003 and currently do not adequately address the security of DoD SCADA systems. This research sampled U.S. Air Force Civil Engineering subject matter experts representing eight Major Commands that manage and operate SCADA systems. They ranked 30 IA controls in three categories, and evaluated eight SCADA specific IA controls for inclusion into …

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Developing An Effective And Efficient Real Time Strategy Agent For Use As A Computer Generated Force, Kurt Weissgerber Mar 2010

Developing An Effective And Efficient Real Time Strategy Agent For Use As A Computer Generated Force, Kurt Weissgerber

Theses and Dissertations

Computer Generated Forces (CGF) are used to represent units or individuals in military training and constructive simulation. The use of CGF significantly reduces the time and money required for effective training. For CGF to be effective, they must behave as a human would in the same environment. Real Time Strategy (RTS) games place players in control of a large force whose goal is to defeat the opponent. The military setting of RTS games makes them an excellent platform for the development and testing of CGF. While there has been significant research in RTS agent development, most of the developed agents …

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Utilizing The Digital Fingerprint Method For Secure Key Generation, Jennifer C. Anilao Mar 2010

Utilizing The Digital Fingerprint Method For Secure Key Generation, Jennifer C. Anilao

Theses and Dissertations

This research examines a new way to generate an uncloneable secure key by taking advantage of the delay characteristics of individual transistors. The user profiles the circuit to deduce the glitch count of each output line for each number of selectable buffers added to the circuit. The user can then use this information to generate a specific glitch count on each output line, which is passed to an encryption algorithm as its key. The results detail tests of two configurations for adding a selectable amount of buffers into each glitch circuit in order to induce additional delay. One configuration adds …

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Performance Of Scattering Matrix Decomposition And Color Spaces For Synthetic Aperture Radar Imagery, Manuel E. Arriagada Mar 2010

Performance Of Scattering Matrix Decomposition And Color Spaces For Synthetic Aperture Radar Imagery, Manuel E. Arriagada

Theses and Dissertations

Polarimetrc Synthetic Aperture Radar (SAR) has been shown to be a powerful tool in remote sensing because uses up to four simultaneous measurements giving additional degrees of freedom for processing. Typically, polarization decomposition techniques are applied to the polarization-dependent data to form colorful imagery that is easy for operators systems to interpret. Yet, the presumption is that the SAR system operates with maximum bandwidth which requires extensive processing for near- or real-time application. In this research, color space selection is investigated when processing sparse polarimetric SAR data as in the case of the publicly available \Gotcha Volumetric SAR Data Set, …

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Verification Of Kam Theory On Earth Orbiting Satellites, Christian L. Bisher Mar 2010

Verification Of Kam Theory On Earth Orbiting Satellites, Christian L. Bisher

Theses and Dissertations

This paper uses KAM torus theory and Simplified General Perturbations 4 (SGP4) orbit prediction techniques compiled by Dr. William Wiesel and compares it to Analytical Graphics ® Incorporated (AGI) Satellite Toolkit ® (STK) orbit data. The goal of this paper is to verify KAM torus theory can be used to describe and propagate an Earth satellite orbit with similar accuracy to existing general perturbation techniques. Using SGP4 code including only truncated geopotential effects, KAM torus generating code, and other utilities were used to describe a particular satellite orbit as a torus and then propagate the satellite using traditional and KAM …

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Numerical Investigation Of Pre-Detonator Geometries For Pde Applications, Robert T. Fievisohn Mar 2010

Numerical Investigation Of Pre-Detonator Geometries For Pde Applications, Robert T. Fievisohn

Theses and Dissertations

A parametric study was performed to determine optimal geometries to allow the successful transition of a detonation from a pre-detonator into the thrust tube of a pulse detonation engine. The study was performed using a two-dimensional Euler solver with progress variables to model the chemistry. The geometrical configurations for the simulations look at the effect of shock reflections, flow obstructions, and detonation diffraction to determine successful geometries. It was observed that there are success and failure rates associated with pre-detonators. These success rates appear to be determined by the transverse wave structure of a stably propagating detonation wave and must …

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Validation Of A Novel Approach To Solving Multibody Systems Using Hamilton's Weak Principle, Ashton D. Hainge Mar 2010

Validation Of A Novel Approach To Solving Multibody Systems Using Hamilton's Weak Principle, Ashton D. Hainge

Theses and Dissertations

A novel approach for formulating and solving for the dynamic response of multibody systems has been developed using Hamilton’s Law of Varying Action as its unifying principle. In order to assure that the associated computer program is sufficiently robust when applied across a wide range of dynamic systems, the program must be verified and validated. The purpose of the research was to perform the verification and validation of the program. Results from the program were compared with closed-form and numerical solutions of simple systems, such as a simple pendulum and a rotating pendulum. The accuracy of the program for complex …

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Fuel Savings Opportunities From Air Refueling, Murat Toydas Mar 2010

Fuel Savings Opportunities From Air Refueling, Murat Toydas

Theses and Dissertations

Fuel is a critical strategic asset for military aviation operations, yet is increasingly expensive. Air refueling offers both the opportunity to extend aircraft range and the potential to save fuel by enabling a transport aircraft to depart with less fuel in exchange for additional cargo. We evaluate the practicality of air refueling in terms of fuel savings versus distance and cargo quantity, by introducing two non-linear optimization models that examine the tradeoff between departure fuel weight and loaded cargo for given origin, destination, and tanker base positions and freight quantities to be moved. We use various numerical example scenarios to …

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The Uav Continuous Coverage Problem, Taegyun Ha Mar 2010

The Uav Continuous Coverage Problem, Taegyun Ha

Theses and Dissertations

The purpose of this research is to develop a method to find an optimal UAV cyclic schedule to provide maximum coverage over a target area to support an ISR mission. The goal is to reach continuous coverage. UAV continuous coverage of a target area is crucial for the success of an ISR mission. Even the smallest coverage gap may jeopardize the success of the mission. Ideally it is desirable to obtain continuous coverage of a target area but the stochastic nature of the problem makes continuous coverage without gaps unlikely. However, it is still possible to obtain a high coverage …

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Modeling The Fate Of Groundwater Contaminants Resulting From Leakage Of Butanol-Blended Fuel, Khai H. Vuong Mar 2010

Modeling The Fate Of Groundwater Contaminants Resulting From Leakage Of Butanol-Blended Fuel, Khai H. Vuong

Theses and Dissertations

Fuel spills and leaks from storage tanks can contaminate groundwater. Typically in groundwater, hazardous aromatic hydrocarbons like benzene are attenuated through natural processes. However, it is possible that adding butanol to gasoline will interfere with these natural attenuation processes, so that spills and leaks of alternative fuels containing biobutanol may result in more persistent hazardous aromatic hydrocarbon plumes. This effect has already been observed with ethanol, which is currently added to gasoline. A numerical model was developed to simulate the subsurface fate and transport of butanol-blended fuel to assess the potential impacts of butanol on the natural attenuation of benzene. …

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Simulation Of A Diode Pumped Alkali Laser, A Three Level Numerical Approach, Shawn W. Hackett Mar 2010

Simulation Of A Diode Pumped Alkali Laser, A Three Level Numerical Approach, Shawn W. Hackett

Theses and Dissertations

This paper develops a three level model for a continuous wave diode pumped alkali laser by creating rate equations based on a three level system. The three level system consists of an alkali metal vapor, typically Rb or Cs, pumped by a diode from the 2S1/2 state to the 2P3/2 , a collisional relaxation from 2P3/2 to 2P1/ 2 , and then lasing from 2P1/2 to 2S1/2 . The hyperfine absorption and emission cross sections for these transitions are developed in detail. Differential equations for intra-gain pump attenuation …

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Passive Ranging Using Infra-Red Atmospheric Attenuation, Douglas J. Macdonald Mar 2010

Passive Ranging Using Infra-Red Atmospheric Attenuation, Douglas J. Macdonald

Theses and Dissertations

Methods of estimating range to an emissive target based on the depth of an atmospheric absorption band are demonstrated. The present work uses measurements of the CO2 absorption band centered at 2.0 µm where signal-to-background ratios are maximum for many applications. Model results, based on high-resolution transmission molecular absorption (HITRAN) database cross sections, are used to predict range accuracy at ranges of up to 50 km and are compared with short range (<5km) experimental results. The spectra of 23 high explosive events were used to validate the model. Using the assumption of a blackbody spectrum, extracted ranges consistently underestimated the true range by approximately 13%. By incorporating the stoichiometry of the fireball from previous research and using particulate contribution as a parameter, the error for the range estimates could be reduced to 3%.

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Scene Change Artifacts In Fourier Transform Spectroscopy Of Temporally Changing Sources, Anthony M. Young Mar 2010

Scene Change Artifacts In Fourier Transform Spectroscopy Of Temporally Changing Sources, Anthony M. Young

Theses and Dissertations

Improved understanding of midwave infrared (1-5 micron) spectral emissions from detonation fireballs is needed to develop phenomenological models for battle space optical forensics. The ability to measure radiance over a wide band pass at arbitrary resolutions make Fourier-transform spectrometers (FTS) an attractive tool. However, interferometer based spectroscopic measurements can be corrupted when the observed intensity changes during data acquisition. While small, random fluctuations in scene intensity translate into noise, systematic variations introduce scene-change artifacts (SCAs) into Fourier-transformed spectrum.

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Application Of Satellite-Derived Wind Profiles To Joint Precision Airdrop System (Jpads) Operations, David C. Meier Mar 2010

Application Of Satellite-Derived Wind Profiles To Joint Precision Airdrop System (Jpads) Operations, David C. Meier

Theses and Dissertations

The Joint Precision Airdrop System has revolutionized military airdrop capability, allowing accurate delivery of equipment and supplies to smaller drop zones, from higher altitudes than was previously possible. This capability depends on accurate wind data which is currently provided by a combination of high-resolution forecast models and GPS dropsondes released in the vicinity of the dropzone shortly before the airdrop. This research develops a windprofiling algorithm to derive the needed wind data from passive IR satellite soundings, eliminating the requirement for a hazardous dropsonde pass near the drop zone, or allowing the dropsonde to be dropped farther from the dropzone. …

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Development And Demonstration Of A Field-Deployable Fast Chromotomographic Imager, Daniel C. O'Dell Mar 2010

Development And Demonstration Of A Field-Deployable Fast Chromotomographic Imager, Daniel C. O'Dell

Theses and Dissertations

A field deployable hyperspectral imager utilizing chromotomography (CT), with a direct vision prism (DVP) as the dispersive element, has been constructed at AFIT. This research is focused on the development and demonstration of the CT imager. An overview of hyperspectral imaging, chromotomography, a synopsis of reconstruction algorithms, and other CT instruments are given. The importance of component alignment, instrument calibration, and exact prism angular position data are discussed. A simplistic \shift and add" reconstruction algorithm was utilized for this research. Although limited in its ability to reconstruct a spatially and spectrally diverse scene, the algorithm was adequate for the testing …

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Monocular Passive Ranging By An Optical System With Band Pass Filtering, Joel R. Anderson Mar 2010

Monocular Passive Ranging By An Optical System With Band Pass Filtering, Joel R. Anderson

Theses and Dissertations

An instrument for monocular passive ranging based on atmospheric oxygen absorption near 762 nm has been designed, built and deployed to track emissive targets, including the plumes from jet engines or rockets. An intensified CCD array is coupled to variable band pass liquid crystal display filter and 3.5 – 8.8 degree field of view optics to observe the target. By recording sequential images at 7 Hz in three 6 nm width bands, the transmittance of the R-branch of the O2 (X-b) (0,0) band is determined. A metric curve for determining range from transmittance is developed using the HITRAN spectral …

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Numerical Investigation Of Statistical Turbulence Effects On Beam Propagation Through 2-D Shear Mixing Layer, James C. Bowers Mar 2010

Numerical Investigation Of Statistical Turbulence Effects On Beam Propagation Through 2-D Shear Mixing Layer, James C. Bowers

Theses and Dissertations

A methodology is developed for determining the validity of making a statistical turbulent approach using Kolmogorov theory to an aero-optical turbulent ow. Kolmogorov theory provides a stochastic method that has a greatly simplified and robust method for calculating atmospheric turbulence effects on optical beam propagation, which could simplify similar approaches to chaotic aero-optical flows. A 2-D laminar Navier-Stokes CFD Solver (AVUS) is run over a splitter plate type geometry to create an aero-optical like shear mixing layer turbulence field. A Matlab algorithm is developed to import the flow data and calculates the structure functions, structure constant, and Fried Parameter ( …

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In-Situ, Gate Bias Dependent Study Of Neutron Irradiation Effects On Algan/Gan Hfets, Janusz K. Mikina Mar 2010

In-Situ, Gate Bias Dependent Study Of Neutron Irradiation Effects On Algan/Gan Hfets, Janusz K. Mikina

Theses and Dissertations

AlGaN/GaN Heterostructure Field Effect Transistors (HFETs) have come under increased study in recent years due to their highly desirable material and electrical properties and survivability even during and after exposure to extreme temperature and radiation environments. In this study, unpassivated and SiN passivated Al0.27Ga0.73N/GaN HFETs were subjected to neutron radiation at 120 K. The primary focus of the research was the effects of neutron irradiation on drain current, gate leakage current, threshold voltage shift, gate-channel capacitance, and the effects of biasing the gate during irradiation. In-situ measurements were conducted on transistor current, gate-channel capacitance, and gate …

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Experimental Validation Techniques For The Heleeos Off-Axis Laser Propagation Model, John D. Haiducek Mar 2010

Experimental Validation Techniques For The Heleeos Off-Axis Laser Propagation Model, John D. Haiducek

Theses and Dissertations

The High Energy Laser End-to-End Operational Simulation (HELEEOS) off-axis scattering algorithm is designed to predict the irradiance that will be detected at a given off-axis location due to atmospheric scattering of a high-energy laser. The HELEEOS system models the propagation of the laser through the atmosphere, accounting for such effects as turbulence, thermal blooming, and atmospheric absorption. The HELEEOS off-axis scattering algorithm uses the scattering phase functions of the Mie scattering models to predict the amount of radiation that will be scattered toward a particular observation location from each point along the beam path, and the total irradiance that will …

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Time Dependent Channel Packet Calculation Of Two Nucleon Scattering Matrix Elements, Brian S. Davis Mar 2010

Time Dependent Channel Packet Calculation Of Two Nucleon Scattering Matrix Elements, Brian S. Davis

Theses and Dissertations

A new approach to calculating nucleon-nucleon scattering matrix elements using a proven atomic time-dependent wave packet technique is investigated. Wave packets containing centripetal barrier information are prepared in close proximity to nuclear well. This is accomplished by first using an analytic equation to determine the wave packets in a suitable intermediate asymptotic state where the centripetal barrier is negligible. Then, the split operator technique is used to propagate the wave packets back to their original positions under the full Hamiltonian. Here, one wave packet is held stationary while the other is allowed to evolve and explore the nuclear well. Scattering …

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The Material Properties Of Cssnbr3 And Csbr:Sn-1% And Their Potential As Scintillator Detector Material, Neal B. Kleinschmidt Mar 2010

The Material Properties Of Cssnbr3 And Csbr:Sn-1% And Their Potential As Scintillator Detector Material, Neal B. Kleinschmidt

Theses and Dissertations

The search for superior nuclear radiation detection materials is ongoing. Current scintillator materials using Thallium doped Sodium Iodide or Cesium Iodide are the benchmarks for ease of use and quick identification of isotope species. This research aims to explore Cesium Bromide doped with 1% molar tin (CsBr:Sn-1%) and Cesium Tin Bromide (CsSnBr3) as candidate materials for a new scintillator. The techniques of Extended X-Ray Absorption Fine Structure (EXAFS), X-Ray Absorption Near Edge Structure (XANES) and Cathodoluminescence are used to determine the suit- ability of CsSnBr3 and CsBr:Sn-1% with Sn4+ as a potential scintillator materials and explore their …

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Uncertainty Quantification Of Multi-Component Isotope-Separation Cascade Model, Khoi D. Tran Mar 2010

Uncertainty Quantification Of Multi-Component Isotope-Separation Cascade Model, Khoi D. Tran

Theses and Dissertations

Monte Carlo uncertainty quantification (UQ) capability has been added to a code for modeling multi-component steady-state isotope-separation enrichment cascades to characterize the propagation of uncertainties in input data that define the cascade and the feed. Random samples of error for every computational input are drawn from its individual uncertainty distribution and added to the inputs, creating a set of enrichment cascade problems with perturbed inputs. The set of problems is solved using the verified code. The cascade outputs are then characterized using the empirical cumulative distribution. The uncertainty output data are analyzed to gain new insights into the behaviors of …

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Nuclear Forensics: Measurements Of Uranium Oxides Using Time-Of-Flight Secondary Ion Mass Spectrometry (Tof-Sims), Wesley A. Schuler Mar 2010

Nuclear Forensics: Measurements Of Uranium Oxides Using Time-Of-Flight Secondary Ion Mass Spectrometry (Tof-Sims), Wesley A. Schuler

Theses and Dissertations

Over the past decade, law enforcement, governmental and public agencies have been stymied by the threat of the trafficking of nuclear materials. During this time span, reports from the International Atomic Energy Agency of illicit trafficking have increased eightfold from 20 to 160. For this reason, nuclear forensics is a burgeoning science focused on the identification of seized special nuclear materials. Identification of these materials is based upon the wealth of information that can be obtained by applying multiple analytical and measurement technologies. All of the information gained from each sample can then be used to further characterize other samples …

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