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Articles 31 - 60 of 278
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Exploring The Dynamics And Modeling National Budget As A Supply Chain System: A Proposal For Reengineering The Budgeting Process And For Developing A Management Flight Simulator, Christoforos Kalloniatis
Exploring The Dynamics And Modeling National Budget As A Supply Chain System: A Proposal For Reengineering The Budgeting Process And For Developing A Management Flight Simulator, Christoforos Kalloniatis
Theses and Dissertations
In the Science of Economics, there has been a debate about the optimal fiscal and budgetary policy that should be implemented by governments. On the one side, the advocates of the Keynesian Theory assert that in recession times governments should run budgets with deficits, in order to stimulate the economy, while the supporters of the Balanced Budget Theory, on the contrary, underscores the need to reduce and even eliminate the budget deficits. However, previous experience shows that both theories often failed to accomplish their goals, because they underestimated a very sensitive parameter: national budgets are not just an estimate of …
The Characterization Of Material Properties And Structural Dynamics Of The Manduca Sexta Forewing For Application To Flapping Wing Micro Air Vehicle Design, Ryan P. O'Hara
Theses and Dissertations
The Manduca Sexta species of moth serves as a source of biological inspiration for the future of micro air vehicle flapping flight. The ability of this species to hover in flapping flight has warranted investigation into the critical material, structural, and geometric properties of the forewing of this biological specimen. A rigorous morphological study of the Manduca Sexta forewing was conducted to characterize the physical and material properties of the biological forewing for the purpose of developing an advanced parametric three dimensional model finite element analysis (FEA) model. This FEA model was tuned to match the experimentally determined structural dynamics …
Passive Synthetic Aperture Radar Imaging Using Commercial Ofdm Communication Networks, Jose R. Gutierrez Del Arroyo
Passive Synthetic Aperture Radar Imaging Using Commercial Ofdm Communication Networks, Jose R. Gutierrez Del Arroyo
Theses and Dissertations
Modern communication systems provide myriad opportunities for passive radar applications. OFDM is a popular waveform used widely in wireless communication networks today. Understanding the structure of these networks becomes critical in future passive radar systems design and concept development. This research develops collection and signal processing models to produce passive SAR ground images using OFDM communication networks. The OFDM-based WiMAX network is selected as a relevant example and is evaluated as a viable source for radar ground imaging. The monostatic and bistatic phase history models for OFDM are derived and validated with experimental single dimensional data. An airborne passive collection …
Characteristics, Causes, And Evaluation Of Helicopter Particulate Obstruction, Michael P. Sullivan
Characteristics, Causes, And Evaluation Of Helicopter Particulate Obstruction, Michael P. Sullivan
Theses and Dissertations
A comprehensive approach to evaluation of rotorcraft brownout under degraded visual environmental conditions is presented. The results of a literature search covering the current state of brownout research are summarized. The brownout dust cloud generated by modern rotorcraft is analyzed and characterized using photographic and video data, coupled with examination of previous computer modeling techniques. A modeling analysis is performed in order to relate aircraft design and operating parameters to brownout dust cloud size is performed. The effect of vorticity in brownout dust cloud rollup is included. An augmented rating scale for pilot assessment is proposed for operational use, and …
Cfd Transient Simulation Of An Isolator Shock Train In A Scramjet Engine, Troy C. Hoeger
Cfd Transient Simulation Of An Isolator Shock Train In A Scramjet Engine, Troy C. Hoeger
Theses and Dissertations
For hypersonic flight, the scramjet engine uses an isolator to contain the pre-combustion shock train formed by the pressure difference between the inlet and the combustion chamber. If this shock train were to reach the inlet, it would cause an engine unstart, disrupting the flow through the engine and leading to a loss of thrust and potential loss of the vehicle. Prior to this work, a Computational Fluid Dynamics (CFD) simulation of the isolator was needed for simulating and characterizing the isolator flow and for finding the relationship between back pressure and changes in the location of the leading edge …
Mapping Nuclear Fallout Using The Weather Research & Forecasting (Wrf) Model, Joseph C. Schofield
Mapping Nuclear Fallout Using The Weather Research & Forecasting (Wrf) Model, Joseph C. Schofield
Theses and Dissertations
There are many models that attempt to predict transport & dispersion (T&D) of particulate matter in the sensible atmosphere. The majority of these existing models are unable to incorporate atmospheric processes such wet deposition through scavenging and cloud condensation nuclei (CCN) formation. To this end, the numerical weather prediction (NWP) model known as the Weather Research & Forecasting with Chemistry (WRF/Chem) Model is studied to determine its suitability as a potential tool for predicting particulate T&D following an atmospheric nuclear detonation. This is done by modifying relevant modules, originally designed to predict the settling of volcanic ash, such that a …
Ballistic Flash Characterization Of Entry-Side Flash, David J. Peyton
Ballistic Flash Characterization Of Entry-Side Flash, David J. Peyton
Theses and Dissertations
Aircraft survivability is a broad subject that encompasses many fields and subjects. An important part of aircraft survivability is fire prevention. Flashes created by ballistic impacts are a very real threat to aircraft because they can start fires or cause explosions. In an effort to better protect against these flashes, this study seeks to further the understanding and characterization of them. Recent research on this subject has been greatly helped by the use of high-speed video footage of flash events. This footage has led to new algorithms and methodologies for how to characterize a flash. A preliminary predictive model of …
Freedrop Testing And Cfd Simulation Of Ice Models From A Cavity Into Supersonic Flow, Thomas J. Flora
Freedrop Testing And Cfd Simulation Of Ice Models From A Cavity Into Supersonic Flow, Thomas J. Flora
Theses and Dissertations
Weapon release at supersonic speeds from an internal bay is highly advantageous. For this reason, both experimental and numerical methods were used to investigate store separation from a cavity (L=D=4.5) into Mach 2.94 flow. The experiment used a piezoresistive pressure transducer, Schlieren and high-speed photography for data acquisition. The computational solution used the OVERFLOW solver. A sphere and a Mk-82, scaled to 1:20, were formed using frozen tap water. The sphere model was freedrop tested experimentally and computationally, while the sub-scale store shaped model was freedrop tested experimentally. The total pressure was varied to alter the dynamic response of the …
Systems Engineering Applications For Small Business Innovative Research (Sbir) Projects, Phillip J. O'Connell
Systems Engineering Applications For Small Business Innovative Research (Sbir) Projects, Phillip J. O'Connell
Theses and Dissertations
This research defined Systems Engineering applications for Small Business Innovative Research (SBIR) projects and answered five research questions addressing the essential elements and application of SE processes within the SBIR community. The research identified that current DoD and Air Force SE Policy do not specifically address SBIR projects. This research identified the need to tailor a SE approach for SBIR projects as overarching policy is not applicable in all cases. The culmination of this effort defined the current SE tasks applicable for the SBIR community.
Effects Of Front-Loading And Stagger Angle On Endwall Losses Of High Lift Low Pressure Turbine Vanes, Michael E. Lyall
Effects Of Front-Loading And Stagger Angle On Endwall Losses Of High Lift Low Pressure Turbine Vanes, Michael E. Lyall
Theses and Dissertations
Past efforts to reduce the airfoil count in low pressure turbines have produced high lift profiles with unacceptably high endwall loss. The purpose of the current work is to suggest alternative approaches for reducing endwall losses. The effects of the fluid mechanics and high lift profile geometry are considered. Mixing effects of the mean flow and turbulence fields are decoupled to show that mean flow shear in the endwall wake is negligible compared to turbulent shear, indicating that turbulence dissipation is the primary cause of total pressure loss. The mean endwall flow field does influence total pressure loss by causing …
The In-Transit Vigilant Covering Tour Problem Of Routing Unmanned Ground Vehicles, Huang Teng Tan
The In-Transit Vigilant Covering Tour Problem Of Routing Unmanned Ground Vehicles, Huang Teng Tan
Theses and Dissertations
The routing of unmanned ground vehicles for the surveillance and protection of key installations is modeled as a new variant of the Covering Tour Problem (CTP). The CTP structure provides both the routing and target sensing components of the installation protection problem. Our variant is called the in-transit Vigilant Covering Tour Problem (VCTP) and considers not only the vertex cover but also the additional edge coverage capability of the unmanned ground vehicle while sensing in-transit between vertices. The VCTP is formulated as a Traveling Salesman Problem (TSP) with a dual set covering structure involving vertices and edges. An empirical study …
Genetic Algorithm Optimization Of A Film Cooling Array On A Modern Turbine Inlet Vane, Jamie J. Johnson
Genetic Algorithm Optimization Of A Film Cooling Array On A Modern Turbine Inlet Vane, Jamie J. Johnson
Theses and Dissertations
In response to the need for more advanced gas turbine cooling design methods that factor in the 3-D flowfield and heat transfer characteristics, this study involves the computational optimization of a pressure side film cooling array on a modern turbine inlet vane. Latin hypersquare sampling, genetic algorithm reproduction, and Reynolds-Averaged Navier Stokes (RANS) computational fluid dynamics (CFD) as an evaluation step are used to assess a total of 1,800 film cooling designs over 13 generations. The process was efficient due to the Leo CFD code's ability to estimate cooling mass flux at surface grid cells using a transpiration boundary condition, …
Rough-Cut Capacity Planning In Multimodal Freight Transportation Networks, Robert B. Hartlage
Rough-Cut Capacity Planning In Multimodal Freight Transportation Networks, Robert B. Hartlage
Theses and Dissertations
A main challenge in transporting cargo for United States Transportation Command (USTRANSCOM) is in mode selection or integration. Demand for cargo is time sensitive and must be fulfilled by an established due date. Since these due dates are often inflexible, commercial carriers are used at an enormous expense, in order to fill the gap in organic transportation asset capacity. This dissertation develops a new methodology for transportation capacity assignment to routes based on the Resource Constrained Shortest Path Problem (RCSP). Routes can be single or multimodal depending on the characteristics of the network, delivery timeline, modal capacities, and costs. The …
Unsteady Specific Work And Isentropic Efficiency Of A Radial Turbine Driven By Pulsed Detonations, Kurt P. Rouser
Unsteady Specific Work And Isentropic Efficiency Of A Radial Turbine Driven By Pulsed Detonations, Kurt P. Rouser
Theses and Dissertations
There has been longstanding government and industry interest in pressure-gain combustion for use in Brayton cycle based engines. Theoretically, pressure-gain combustion allows heat addition with reduced entropy loss. The pulsed detonation combustor (PDC) is a device that can provide such pressure-gain combustion and possibly replace typical steady deflagration combustors. The PDC is inherently unsteady, however, and comparisons with conventional steady deflagration combustors must be based upon time-integrated performance variables. In this study, the radial turbine of a Garrett automotive turbocharger was coupled directly to and driven, full admission, by a PDC in experiments fueled by hydrogen or ethylene. Data included …
Emulating Industrial Control System Field Devices Using Gumstix Technology, Dustin Berman
Emulating Industrial Control System Field Devices Using Gumstix Technology, Dustin Berman
Theses and Dissertations
Industrial Control Systems (ICS) have an inherent lack of security and situational awareness capabilities at the field device level. Yet these systems comprise a significant portion of the nation's critical infrastructure. Currently, there is little insight into the characterization of attacks on ICS. Stuxnet provided an initial look at the type of tactics that can be employed to create physical damage via cyber means. The question still remains, however, as to the extent of malware and attacks that are targeting the critical infrastructure, along with the various methods employed to target systems associated with the ICS environment. This research presents …
Covert Android Rootkit Detection: Evaluating Linux Kernel Level Rootkits On The Android Operating System, Robert C. Brodbeck
Covert Android Rootkit Detection: Evaluating Linux Kernel Level Rootkits On The Android Operating System, Robert C. Brodbeck
Theses and Dissertations
This research developed kernel level rootkits for Android mobile devices designed to avoid traditional detection methods. The rootkits use system call hooking to insert new handler functions that remove the presence of infection data. The effectiveness of the rootkit is measured with respect to its stealth against detection methods and behavior performance benchmarks. Detection method testing confirms that while detectable with proven tools, system call hooking detection is not built-in or currently available in the Google Play Android App Store. Performance behavior benchmarking showed that system call hooking affects the completion time of the targeted system calls. However, this delay's …
Adaptive Routing Algorithm For Priority Flows In A Network, Timothy J. Carbino
Adaptive Routing Algorithm For Priority Flows In A Network, Timothy J. Carbino
Theses and Dissertations
This research presents the development of an Adaptive Routing Algorithm for Priority (ARAP) flows in a Network. Devices in today's battle space require information to function. Additional bandwidth requirements for such devices place an increased burden on the already congested networks in the battle space. Some devices require real time information (high priority) and other devices will not require real time information (low priority). Existing protocols treat the network like an opaque entity and have little knowledge of user requirements. User requirement information is available in tactical networks and we can take advantage of the known requirements to better optimize …
Decentralized Riemannian Particle Filtering With Applications To Multi-Agent Localization, Martin J. Eilders
Decentralized Riemannian Particle Filtering With Applications To Multi-Agent Localization, Martin J. Eilders
Theses and Dissertations
The primary focus of this research is to develop consistent nonlinear decentralized particle filtering approaches to the problem of multiple agent localization. A key aspect in our development is the use of Riemannian geometry to exploit the inherently non-Euclidean characteristics that are typical when considering multiple agent localization scenarios. A decentralized formulation is considered due to the practical advantages it provides over centralized fusion architectures. Inspiration is taken from the relatively new field of information geometry and the more established research field of computer vision. Differential geometric tools such as manifolds, geodesics, tangent spaces, exponential, and logarithmic mappings are used …
Simulation Modeling And Analysis Of The Impact Of Individual Mobility Augmentee Loss At The Tanker Airlift Control Center, Megan A. Leiter
Simulation Modeling And Analysis Of The Impact Of Individual Mobility Augmentee Loss At The Tanker Airlift Control Center, Megan A. Leiter
Theses and Dissertations
The Tanker Airlift Control Center (TACC) operates as the execution arm for Air Mobility Command's Global Reach mission. The Command and Control Directorate (XOC) monitors the execution of missions tasked to the 18th Air Force. Approximately 70% of the personnel on the operations floor are considered Individual Mobility Augmentees (IMA). Adjustments in manpower, specifically the loss of IMAs, at the TACC/XOCG may impact their responsiveness to mission deviations. This research develops a discrete event simulation using a combination of SME and historical data to capture the activities of a section of the personnel on the operations floor and the potential …
Intra-Procedural Path-Insensitive Grams (I-Grams) And Disassembly Based Features For Packer Tool Classification And Detection, Scott E. Gerics
Intra-Procedural Path-Insensitive Grams (I-Grams) And Disassembly Based Features For Packer Tool Classification And Detection, Scott E. Gerics
Theses and Dissertations
The DoD relies on over seven million computing devices worldwide to accomplish a wide range of goals and missions. Malicious software, or malware, jeopardizes these goals and missions. However, determining whether an arbitrary software executable is malicious can be difficult. Obfuscation tools, called packers, are often used to hide the malicious intent of malware from anti-virus programs. Therefore detecting whether or not an arbitrary executable file is packed is a critical step in software security. This research uses machine learning methods to build a system, the Polymorphic and Non-Polymorphic Packer Detection (PNPD) system, that detects whether an executable is packed …
The White-Hat Bot: A Novel Botnet Defense Strategy, Tyrone C. Gubler
The White-Hat Bot: A Novel Botnet Defense Strategy, Tyrone C. Gubler
Theses and Dissertations
Botnets are a threat to computer systems and users around the world. Botmasters can range from annoying spam email propagators to nefarious criminals. These criminals attempt to take down networks or web servers through distributed denial-of-service attacks, to steal corporate secrets, or to launder money from individuals or corporations. As the number and severity of successful botnet attacks rise, computer security experts need to develop better early-detection and removal techniques to protect computer networks and individual computer users from these very real threats. I will define botnets and describe some of their common purposes and current uses. Next, I will …
Enhancing Trust In The Smart Grid By Applying A Modified Exponentially Weighted Averages Algorithm, Andrew T. Kasperek
Enhancing Trust In The Smart Grid By Applying A Modified Exponentially Weighted Averages Algorithm, Andrew T. Kasperek
Theses and Dissertations
The main contribution of this thesis is the development and application of a modified Exponentially Weighted Moving Algorithm (EWMA) algorithm, and its ability to robustly function in the face varying numbers of bad (malicious or malfunctioning) Special Protection System (SPS) nodes. Simulation results support the use of the proposed modified EWMA reputation based trust module in SPSs within a smart grid environment. This modification results in the ability to easily maintain the system above the minimum acceptable frequency of 58.8 Hz at the 95% confidence interval, when challenged with test cases containing 5, 10 and 15 bad node test cases …
Cyberspace And Real-World Behavioral Relationships: Towards The Application Of Internet Search Queries To Identify Individuals At-Risk For Suicide, Casey C. Miller
Cyberspace And Real-World Behavioral Relationships: Towards The Application Of Internet Search Queries To Identify Individuals At-Risk For Suicide, Casey C. Miller
Theses and Dissertations
The Internet has become an integral and pervasive aspect of society. Not surprisingly, the growth of ecommerce has led to focused research on identifying relationships between user behavior in cyberspace and the real world - retailers are tracking items customers are viewing and purchasing in order to recommend additional products and to better direct advertising. As the relationship between online search patterns and real-world behavior becomes more understood, the practice is likely to expand to other applications. Indeed, Google Flu Trends has implemented an algorithm that accurately charts the relationship between the number of people searching for flu-related topics on …
Detecting Hardware-Assisted Hypervisor Rootkits Within Nested Virtualized Environments, Daniel B. Morabito
Detecting Hardware-Assisted Hypervisor Rootkits Within Nested Virtualized Environments, Daniel B. Morabito
Theses and Dissertations
Virtual machine introspection (VMI) is intended to provide a secure and trusted platform from which forensic information can be gathered about the true behavior of malware within a guest. However, it is possible for malware to escape a guest into the host and for hypervisor rootkits, such as BluePill, to stealthily transition a native OS into a virtualized environment. This research examines the effectiveness of selected detection mechanisms against hardware-assisted virtualization rootkits (HAV-R) within a nested virtualized environment. It presents the design, implementation, analysis, and evaluation of a hypervisor rootkit detection system which exploits both processor and translation lookaside buffer-based …
Process Flow Features As A Host-Based Event Knowledge Representation, Benhur E. Pacer
Process Flow Features As A Host-Based Event Knowledge Representation, Benhur E. Pacer
Theses and Dissertations
The detection of malware is of great importance but even non-malicious software can be used for malicious purposes. Monitoring processes and their associated information can characterize normal behavior and help identify malicious processes or malicious use of normal process by measuring deviations from the learned baseline. This exploratory research describes a novel host feature generation process that calculates statistics of an executing process during a window of time called a process flow. Process flows are calculated from key process data structures extracted from computer memory using virtual machine introspection. Each flow cluster generated using k-means of the flow features represents …
Cross Hallway Detection And Indoor Localization Using Flash Laser Detection And Ranging, Istvan M. Prileszky
Cross Hallway Detection And Indoor Localization Using Flash Laser Detection And Ranging, Istvan M. Prileszky
Theses and Dissertations
A flash LADAR is investigated as a source of navigation information to support cross-hallway detection and relative localization. To accomplish this, a dynamic, flexible simulation was developed that simulated the LADAR and the noise of a LADAR system. Using simulated LADAR data, algorithms were developed that were shown to be effective at detecting cross hallways in simulated ideal environments and in simulated environments with noise. Relative position was determined in the same situations. A SwissRanger SR4000 flash LADAR was then used to collect real data and to verify algorithm performance in real environments. Hallway detection was shown to be possible …
An Application Of Con-Resistant Trust To Improve The Reliability Of Special Protection Systems Within The Smart Grid, Crystal M. Shipman
An Application Of Con-Resistant Trust To Improve The Reliability Of Special Protection Systems Within The Smart Grid, Crystal M. Shipman
Theses and Dissertations
This thesis explores an application of a con-resistant trust mechanism to improve the performance of communications-based special protection systems to further enhance their effectiveness and resiliency. New initiatives in the energy sector are paving the way for the emergent communications-based smart grid technology. Smart grids incorporate modern technologies in an effort to be more reliable and efficient. However, with the benefits of this new technology comes added risk. This research utilizes a con-resistant trust mechanism as a method to quickly identify malicious or malfunctioning protection system nodes in order to mitigate the resulting instabilities in the smart grid. The feasibility …
Characterization And Measurements From The Infrared Grazing Angle Reflectometer, Michael R. Benson
Characterization And Measurements From The Infrared Grazing Angle Reflectometer, Michael R. Benson
Theses and Dissertations
A commonly used metric for measuring the reflective properties of a sample is Directional Hemispherical Reflectance (DHR). The Infrared Grazing Angle Reflectometer measures DHR at high angles of incidence. To facilitate this measurement, a novel three dimensional multi-face pyroelectric detector is used. This detector can theoretically measure better than 98% of the light reflected by the sample, regardless of the diffusivity of the sample measured. The setup of this equipment is discussed, and the procedure for calibration is derived. Several of the difficulties in performing measurements are described, and several sample measurements are discussed.
Calibration Of A Silver Detector Using A Pube Source, Melanie E. Mace
Calibration Of A Silver Detector Using A Pube Source, Melanie E. Mace
Theses and Dissertations
During the initial design of the Field Reversed Compression and Heating Experiment (FRCHX), magnetohydrodynamic simulations performed by Los Alamos National Laboratory using MACH2 predicted a neutron yield on the order of 1012 neutrons. However, Air Force Research Laboratory (AFRL) measurements indicate a total of 107-108 neutrons are generated from the FRCHX. A PuBe source was used to create a burst of neutrons to calibrate an AFRL silver detector based on distance to determine if the four order of magnitude discrepancy was cause by an improperly calibrated detector. It was determined that the calibration equation in use …
Application Of An Imaging Fourier-Transform Spectrometer For The Means Of Combustion Diagnostics, Michael R. Rhoby
Application Of An Imaging Fourier-Transform Spectrometer For The Means Of Combustion Diagnostics, Michael R. Rhoby
Theses and Dissertations
A passive remote sensing technique for accurately monitoring the combustion efficiency of petrochemical flares is greatly desired. A Phase II DOE-funded SBIR lead by Spectral Sciences, Inc. is underway to develop such a method. This paper presents an overview of the progress of AFIT's contribution. A Telops Hyper-Cam Mid-wave infrared imaging Fourier-transform spectrometer is used to examine a flame produced by a Hencken burner. Ethylene fuel was burned at four different equivalency ratios φ = 0:80; 0:91; 1:0 and 1:25. Presented is qualitative spectrally-resolved visualization of a Hencken burner flame and the spatial distribution of combustion by-products. The flame spectra …