| Penetration Physics at the Meso-Scale |
06-Oct-2009 |
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| Authors:
Conrad W Felice; Y M Gupta; WASHINGTON STATE UNIV PULLMAN INST FOR SHOCK PHYSICS AND PHYSICS DEPT
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 | This effort focused on understanding the underlying physics through a multi-scale computational approach to quantify penetrator performance into particulate geologic materials at impact velocities up to 1,500 m/sec. The computational approach employed an explicit, updated Lagrangian finite element formulation that performed 2-D plain strain and axisymmetric analyses of multi-body systems subjected to shock wave loading. To capture the particulate response, a simple elastic-plastic constitutive model was used to represent the ... |
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| Development of a Versatile Conditioning Wind Tunnel for Evaporative Fate Studies |
Oct-2009 |
63 pages |
| Authors:
H D Durst; James E Danberg; Daniel J Weber; Daniel Waysbort; Clayton S Moury; EDGEWOOD CHEMICAL BIOLOGICAL CENTER ABERDEEN PROVING GROUND MD
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 | This report documents the development of a conditioning wind tunnel that allows multiple test samples to be conditioned at identical environmental settings that are used in smaller vapor sampling wind tunnels. The conditioning of multiple samples, especially those involving persistent chemicals, allows for the efficient use of a limited number of instrumented vapor sampling tunnels. Up to nine samples can be sequentially and quickly cycled through the instrumented vapor wind ... |
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| Quantification of Rock Damage from Small Explosions and its Effect on Shear-Wave Generation: Phase I - Homogeneous Crystalline Rock |
30-Sep-2009 |
11 pages |
| Authors:
Jessie L Bonner; Randolph J Martin; Anastasia Stroujkova; Mark Leidig; Peter Boyd; WESTON GEOPHYSICAL CORP LEXINGTON MA
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| Weston Geophysical Corp., New England Research, Inc., and several geotechnical consultants conducted the New England Damage Experiment (NEDE) in central Vermont during July 2008. A series of five explosions using charges having yields of 135 and 270 lbs and three types of explosives were detonated in homogeneous low-fracture density granite. The goal of the experiment was to generate different amounts of rock damage around the source by using explosives with ... |
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| Source and Path Calibration in Regions of Poor Crustal Propagation using Temporary, Large-Aperture, High-Resolution Seismic Arrays |
30-Sep-2009 |
9 pages |
| Authors:
John L Nabelek; Jochen Braunmiller; W S Phillips; OREGON STATE UNIV CORVALLIS
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| Broadband seismic data acquired during the Hi-CLIMB field experiment are used to study seismic events and path propagation in the Nepal Himalaya and south-central Tibetan Plateau. Similarities in regional propagation between Tibet and Iran motivate this new study. The 2002-2005 Hi-CLIMB experiment consisted of 233 stations distributed along a dense 800 km linear north-south array extending from the Himalayan foreland into the central Tibetan Plateau. The main array was flanked ... |
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| Estimating the Uncertainty and Predictive Capabilities of Three-Dimensional Earth Models |
30-Sep-2009 |
11 pages |
| Authors:
Stephen C Myers; Delaine T Reiter; William L Rodi; WESTON GEOPHYSICAL LEXINGTON MA
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| Many three-dimensional models of seismic velocity structure in Eurasia have been developed in recent years by the seismic nuclear monitoring community. Most of these models are not accompanied by quantitative estimates of uncertainty, either in the model velocities themselves or in geophysical observables predicted by the models (e.g., body-wave travel times). Moreover, the various 3D models produced by these studies have not been compared to one another for their predictive ... |
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| Rotorcraft Crash Mishap Analysis |
30-Sep-2009 |
390 pages |
| Authors:
Lance C Labun; SAFE INC TEMPE AZ
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| The method and results of a study using rotary wing crash data from the Army Aviation Mishap database are reported. The study was conducted to support the Full Spectrum Crashworthiness initiative with the objective of providing a current basis for revising the crashworthiness design criteria. For this study, crashes were divided into two types: directly to terrain, and those following an inflight obstacle strike. Thirty percent of the crashes studied ... |
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| Analysis of Silicon Nitride (Si3N4) for Use in a Small Recuperated Turboshaft Engine |
21-Sep-2009 |
8 pages |
| Authors:
Richard L Jr; Stark; Michael J Vick; NAVAL RESEARCH LAB WASHINGTON DC OFF-BOARD COUNTERMEASURES BRANCH
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| This analysis was performed to determine whether silicon nitride (Si3N4) could be used as a material for fabrication of the Small Recuperated Turboshaft Heavy Fuel Engine (SMART-HFE). Oxidation and volatilization of silicon nitride in the presence of water vapor has proven to be an issue under the conditions of turbine combustion. Through the use of previous research, the recession rates of Si3N4 were predicted for various operating conditions. The volatilization ... |
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| Numerical Model Study of the Tuscarawas River below Dover Dam, Ohio |
Sep-2009 |
58 pages |
| Authors:
Richard L Stockstill; Jane M Vaughan; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
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| The U.S. Army Corps of Engineers, Huntington District (LRH) has been charged with upgrading Dover Dam to meet hydrologic design standards and address stability issues. The LRH requested that the U. S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory (CHL), evaluate the flow conditions in the Tuscarawas River downstream of Dover Dam as part of a safety assurance program. The two-dimensional depth-averaged module of the Adaptive Hydraulics ... |
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| An Analysis of Bent Function Properties Using the Transeunt Triangle and the SRC-6 Reconfigurable Computer |
Sep-2009 |
140 pages |
| Authors:
Jennifer L Shafer; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Linear attacks against cryptosystems can be defeated when combiner functions are composed of highly nonlinear Boolean functions. The highest nonlinearity Boolean functions, or bent functions, are not common--especially when they have many variables--bent functions are difficult to find. Understanding what properties are common to bent functions will help ease the search for them. Using the SRC-6 reconfigurable computer, functions can be generated or tested at a rate much higher than ... |
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| Designing a Sensorless Torque Estimator for Direct Torque Control of an Induction Motor |
Sep-2009 |
87 pages |
| Authors:
Athanasios Tsoutsas; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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| Nowadays, transportation is a major cause of air pollution. Electric propulsion could replace the internal combustion engines of automobiles and reduce the emission of exhaust gases. The propulsion of an electric vehicle requires the design of an accurate electromagnetic torque estimator and an efficient control system in order to control the speed of the vehicle. This concept is conveyed through this thesis. An electromagnetic torque calculator of an induction motor ... |
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| Cost Benefit and Capability Analysis of Sea-Base Connectors |
Sep-2009 |
78 pages |
| Authors:
Justin A Dowd; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| In this thesis a cost benefit and capability analysis is conducted on a number of Sea-Base connectors. In conducting this analysis the average yearly Operating and Sustainment (O&S) cost of the connectors studied is used along with specific performance data such as maximum payload (in tons), maximum speed (in knots) when loaded to maximum payload, and maximum range (in nautical miles) when operated at maximum payload and maximum speed to ... |
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| Alternative Methods to Standby Gain Scheduling Following Air Data System Failure |
Sep-2009 |
261 pages |
| Authors:
Matthew W Coldsnow; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The United States Air Force has advanced fighter aircraft that lose the ability to operate in a large portion of their operating flight envelope when an air data system failure is experienced. These aircraft are reverted to a fixed set of standby-gains that limit their maneuverability, degrade handling qualities, and increase susceptibility to departure. The purpose of this research was to determine if three alternative methods of standby-gain-scheduling could provide ... |
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| Particle Deposition onto Enclosure Surfaces |
20-Aug-2009 |
61 pages |
| Authors:
De-Ling Liu; AEROSPACE CORP EL SEGUNDO CA
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| In space applications, the main concern of particle deposition arises from the undesirable effects of surface obscuration on contamination-sensitive surfaces. The development of effective mitigation strategies to minimize particulate contamination requires the understanding of particle transport and deposition as well as the associated physical factors affecting the processes. The knowledge gleaned from the state-of-the-art literature review presented here can be applied to an enclosure scale as small as a spacecraft ... |
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| On-Line Path Generation and Tracking for High-Speed Wheeled Autonomous Vehicles |
18-Aug-2009 |
19 pages |
| Authors:
Panagiotis Tsiotras; GEORGIA TECH RESEARCH INST ATLANTA
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| Study after study has shown the benefits of speed in military operations, both in terms of engaging the enemy, avoiding ambushes and successfully completing the mission. The US Army has been promoting the large-scale deployment of autonomous or semi-autonomous vehicles in the battlefield, either as part of the support supply chain (convoys) or as active participants in the battle zone. It is clear even to the non-expert that these vehicles ... |
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| A Computational Analysis of a Shear Punch Test |
Aug-2009 |
14 pages |
| Authors:
Stephan R Bilyk; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| The intense shearing that occurs in propellants and explosives during impulsive loading can lead to initiation. In an effort to determine useful shear initiation criteria, the U.S. Army Research Laboratory (ARL) has developed a shear punch test using a modified Kolsky bar. Varying the striker bar's velocity and length controls the shear rate and duration. Shear velocities approaching 100 m/s and durations as long as 200 microns are possible. Experimental ... |
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| Mechanical Response and Shear Initiation of Double-Base Propellants |
Aug-2009 |
16 pages |
| Authors:
Stephan R Bilyk; Michael J Scheidler; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| The intense shearing that occurs in propellants during impulsive loading can lead to initiation. In an effort to determine useful shear initiation criteria, the U.S. Army Research Laboratory has developed a dynamic shear punch test using a modified split- Hopkinson bar. Varying the striker bar's velocity and length controls the shear rate and duration. Shear velocities approaching 100 m/s and durations as long as 0.2 ms are possible. Experimental results ... |
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| Ankudinov Ship Squat Predictions - Part 1: Theory, Parameters, and FORTRAN Programs |
Aug-2009 |
16 pages |
| Authors:
Michael J Briggs; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
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| Squat is the reduction in underkeel clearance (UKC) between a vessel at-rest and underway due to the increased flow of water past the moving hull. The forward motion of the ship pushes water ahead of it that must return around the sides and under the keel. This water motion induces a relative velocity between the ship and the surrounding water that causes a water level depression in which the ship ... |
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| On the Effect of a Transverse Acoustic Field on a Flush Shear Coaxial Injector |
13-Jul-2009 |
15 pages |
| Authors:
Douglas Talley; Juan I Rodriguez; Ivett A Leyva; Jeffrey J Graham; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| An experimental study on the effects of an externally-imposed transverse acoustic field in a flush shear coaxial jet is presented. In this case the inner jet recess is zero and both the inner and outer jet exit planes coincide. Since recess is a design variable used when designing new injectors, this study complements previous studies from this group where the injector geometries included a recess. The shear coaxial injector used ... |
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| Mixing Enhancement of Liquid Rocket Engine Injector Flow |
13-Jul-2009 |
21 pages |
| Authors:
Douglas Talley; Ivett Leyva; Juan Rodriquez; Jeffrey Graham; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| An investigation of the mixing enhancement behavior of N2 shear coaxial jets between two injector geometries is presented. A total of 20 cases with one injector geometry and 15 with the other, corresponding to different momentum flux ratios (J's) at subcritical, nearcritical and supercritical pressures are analyzed and compared. The measurements are extracted from 998 backlit images. Acoustic excitation is used to analyze the response of the system to velocity ... |
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| An Ocean Sensor Array to Detect Small-Scale Variability |
Jul-2009 |
5 pages |
| Authors:
Janet Sprintall; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA
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| The specific objectives of this DURIP project were to provide direct measurements of velocity and currents in narrow straits with shallow sill depths in order to: (1) Examine the relative roles of the tidal and longer timescale flows in the generation and evolution of the small-scale dynamical flow features in straits; (2) Determine how the small-scale features evolve with observed across- and along-strait variation in sea level and the corresponding ... |
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| Acceleration of an Initially Moving Projectile: Velocity-Injected Railguns and Their Effect on Pulsed Power |
Jul-2009 |
30 pages |
| Authors:
Del; Miguel Guercio; Alexander Zielinski; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Calculations are performed for an initially moving projectile and a railgun. The initial velocity is provided by a 26-mm-diameter conventional propellant gun. A plasma armature is assumed for the railgun. The capacitor-based, pulsed power supply (PPS), located at barricade C, Aberdeen Proving Ground, MD, is assumed to provide the electrical energy for boosting the velocity to 2.5 km/s. Various scenarios are examined with respect to electrical pulse shape, the effect ... |
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| Improving the Future of the Army's Future Combat Systems Program |
01-Jun-2009 |
87 pages |
| Authors:
Bill Pettus; Jack Wong; Arbi Lazar; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| The Future Combat Systems (FCS) program is the U.S. Army's ambitious attempt to modernize its forces in a systematic way, so that everything interoperates properly. This system of systems approach contrasts with the stove-pipe solutions of the past in which individual systems were designed to meet specific requirements, but with much less thought about how they would interact in the overall force. The stove-pipe approach has worked well enough in ... |
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| DURIP: Vector Sensor Array |
01-Jun-2009 |
11 pages |
| Authors:
Grant B Deane; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB
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| An array of Wilcoxon VS205 vector sensors has been designed, fabricated and deployed at-sea in the shallow waters off the Scripps Institution of Oceanography pier during August of 2008. |
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| Preliminary VHF Radar and High-Data-Rate Optical Turbulence Profile Observations Using a Balloon-Ring Platform: Post Print |
01-Jun-2009 |
36 pages |
| Authors:
Frank D Eaton; Gregory D Nastrom; Demos T Kyrazis; Don G Black; Wiley T Black; R A Black; NASTROM CONSULTING LLC SAINT CLOUD MN
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| A recent measurement campaign at Vandenberg Air Force Base involved taking simultaneous observations with a VHF radar and high-data-rate (1-micron diameter) platinum wires to sense optical turbulence (from temperature fluctuations). The radar observations produce profiles of the refractive index structure parameter, the turbulent kinetic energy, the eddy dissipation rate, the inner scale, the outer scale of turbulence, and wind speed and direction to an altitude of 20 km AGL. The ... |
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| Influence of Structural Flexibility on Flapping Wing Propulsion |
Jun-2009 |
180 pages |
| Authors:
Aaron M McClung; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The influence of structural deformations on the aerodynamic response of a flapping wing configuration was examined using Navier-Stokes based simulation. Two deformation modes, torsion and bending, were considered for an elastic axis along the leading edge of the wing. Both deformation modes influence the velocity and acceleration profile of the wing surface, altering the unsteady aerodynamic phenomena produced by the dynamic wing motion. The spanwise feathering rotation, or torsional response, ... |
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| The Command and Control of the Grand Armee: Napoleon as Organizational Designer |
Jun-2009 |
59 pages |
| Authors:
Norman L Durham; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| The purpose of this thesis is to investigate Napoleon Bonaparte's command and control of the Grand Armee through the lens of organizational design. Napoleon's methodology behind the design of the Grand Armee is analyzed using modern principles of organizational design. The structure that Napoleon created within his organizational design was a vast information network that served as the framework for a highly effective command and control system. This command and ... |
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| Transport Imaging: Developing an Optical Technique to Characterize Bulk Semiconductor Materials for Next Generation Radiation Detectors |
Jun-2009 |
79 pages |
| Authors:
Sarah L Catalano; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Characterization of the mobility-lifetime product is critical to the development of new materials for semiconductor radiation detectors. An optical technique has been developed that allows for the direct determination of the minority carrier diffusion length, drift length, and mobility-lifetime product from a single image of the recombination luminescence in semiconductor materials. Excess carriers are generated using the electron beam in a scanning electron microscope. The charge is then drifted by ... |
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| Progress Toward a Multidimensional Representation of Mortar Interior Ballistics |
Jun-2009 |
38 pages |
| Authors:
John R Schmidt; Michael J Nusca; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Lumped-parameter interior ballistics (IB) codes have had limited success in simulating the IB of mortars due to the complex nature of the firing event. Only near the end of the firing event does the mortar conform to the conventional ballistics model for which lumped-parameter codes were designed. Modified lumped-parameter models are capable of simulating some key mortar variables. There are significant pressure waves developed in mortars, which are due in ... |
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| Mortar Interior Ballistics: Sensitivity Studies Using IBHVG2 and Progress Toward a Multidimensional Representation |
Jun-2009 |
38 pages |
| Authors:
John R Schmidt; Michael J Nusca; Albert W Horst; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Traditionally, the interior ballistic (IB) modeling of mortars has been difficult to achieve because a mortar projectile contains certain energetic components internal to the tail boom. After ignition, high pressure generated by the igniter causes the canister to burst and release hot gases and burning particles into the larger chamber called the launch tube. Subsequently, any external charges ignite and produce gases which accelerate the projectile. A recent advancement to ... |
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| Simulation of Ballistic Impact of a Tungsten Carbide Sphere on a Confined Silicon Carbide Target |
Jun-2009 |
16 pages |
| Authors:
C G Fountzoulas; B A Cheeseman; J C LaSalvia; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The present investigation is a continuation of our previous study on the ability of the phenomenological Johnson-Holmquist model to predict the observed damage induced by spheres of tungsten carbide (WC) striking confined cylinders of silicon carbide (SiC) at velocities between 63 m/s to 500 m/s. In this study, the WC was modeled using the Johnson-Cook plasticity model along with a principal stress failure criterion calibrated with recently available experimental data. ... |
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| A Computational Study of Laminate Transparent Armor Impacted by FSP |
Jun-2009 |
14 pages |
| Authors:
C G Fountzoulas; J M Sands; B A Cheeseman; P G Dehmer; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The current report reports on our efforts to simulate the ballistic impact of a fragment simulating projectile (FSP) into a Lexan 9034 polycarbonate (PC)- polymethyl-methacrylate (PMMA), which was a Plexiglas G manufactured by Atofina Chemicals, - Lexan 9034 Polycarbonate laminate system, with and without the presence of polyurethane adhesive, using the nonlinear analysis software AUTODYN. The simulation results, which included V50 measurements, were compared to the ballistic results from the ... |
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| The New Chemistry of C2 |
Jun-2009 |
78 pages |
| Authors:
Kevin J Cogan; William O Waddell; ARMY WAR COLL CARLISLE BARRACKS PA CENTER FOR STRATEGIC LEADERSHIP
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| Drs. David Alberts and Richard Hayes' book Understanding Command and Control states that the purpose of C2 has remained unchanged since the earliest military forces engaged. But implementing C2 effectively now in the era of transformation can break traditional notions by envisioning a chemical model which incorporates emerging and disruptive technologies arriving at exponentially faster rates. Like carbon chains in organic chemistry, the military C2 organization has grown by adding ... |
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| A Computational Study of the Energy Dissipation Through an Acrylic Target Impacted by Various Size FSP |
Jun-2009 |
14 pages |
| Authors:
C G Fountzoulas; J M Sands; P G Dehmer; J H Yu; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Recent advances in the numerical techniques, higher computing power and materials model have allowed the accurate simulation of the ballistic impact into monolithic and multi-layer transparent armor configurations. In the current effort, the velocity profile during the ballistic impact of 0.22-cal and 0.15-cal fragment simulating projectiles (FSP) into a polymethyl-methacrylate (PMMA) target, which was a Plexiglas G manufactured by Atofina Chemicals was simulated using the ANSYS/AUTODYN commercial software. Our successful ... |
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| Speed Versus Accuracy: A Zero Sum Game |
11-May-2009 |
29 pages |
| Authors:
Jeffrey L Scott; ARMY WAR COLL CARLISLE BARRACKS PA
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| Accuracy maintains the required credibility for an effective information strategy. Speed provides current, relevant information to inform and influence key populations. The requirement and role of speed and accuracy create a zero sum game in information strategy. With the importance of information in today's irregular warfare environment, an effective information strategy is based on decentralization. Operations planned and conducted and the daily interactions of the units and Soldiers on the ... |
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| Analyses of Aircraft Measurement of Atmospheric Turbulence |
16-Apr-2009 |
40 pages |
| Authors:
Jorg M Hacker; Don Wroblewski; FLINDERS UNIV OF SOUTH AUSTRALIA SALISBURY AIRBORNE RESEARCH AUSTRALIA
|
| The analysis of high resolution turbulence measurements obtained over 8 years from a unique aircraft platform have shed light on the phenomena of clear air turbulence (CAT) and optical turbulence (OpT) in the Upper Troposphere and Lower Stratosphere (UTLS) and how they may adversely impact systems of interest to the Air Force. Some notable results include 1. Characterization of cliff-ramp patterns and the use of DNS to provide insight into ... |
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| Objective Estimates of Westward Rossby Wave and Eddy Propagation from Sea Surface Height Analyses |
17-Mar-2009 |
19 pages |
| Authors:
C N Barron; A B Kara; G A Jacobs; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| An objective method to estimate westward propagation of sea surface height (SSH) anomalies is introduced and compared to a subjective technique. Both approaches use time series extracted from global SSH analyses, prepared by optimal interpolation of altimeter data, as described in detail. The cost function used in the objective method calculates the mean along-slope standard deviation, where slope is the reciprocal of propagation speed and defines the angle of linear ... |
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| Interface Conditions for Hybrid RANS/LES Simulations of Complex and Compressible Flows |
06-Mar-2009 |
31 pages |
| Authors:
Ugo Piomelli; Elias Balaras; MARYLAND UNIV COLLEGE PARK DEPT OF MECHANICAL ENGINEERING
|
| We have demonstrated the applicability of synthetic turbulence coupled with the controlled-forcing method to generate eddies at the interface between RANS and LES in hybrid calculations. We obtained shorter transition regions and improved model accuracy. Realistic turbulence can be generated within 5 boundary-layer thicknesses of the RANS/LES interface even in cases in which the data supplied by the RANS is inaccurate, or the assumptions on which the forcing is based ... |
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| A Verification of the COAMPS-TC Model Predictions of Typhoon Nuri (2008) |
01-Mar-2009 |
98 pages |
| Authors:
Jennifer M Hensley; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The objective of this thesis is to examine the predictions of the COAMPS-TC model for Typhoon Nuri during the THORPEX Pacific Asian Regional Campaign (T-PARC) and the Tropical Cyclone Structure 2008 (TCS-08) experiment that occurred in August through October 2008 in the western North Pacific. This case study on Typhoon Nuri examines the dynamic and thermodynamic structure changes of this tropical cyclone, including the intensity, track, radar reflectivity, and azimuthally-averaged ... |
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| Waypoint Generation Based on Sensor Aimpoint |
Mar-2009 |
173 pages |
| Authors:
Shannon M Farrel; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This research develops waypoint generation algorithms required to keep a point of interest (POI) in the field of view (FOV) of a fixed sensor on a micro air vehicle (MAV), in the presence of a constant wind. The waypoint generation algorithms establish waypoints such that a fixed sensor on a MAV at that waypoint and assumed attitude would be pointed directly at the POI. Two scenarios are explored: one where ... |
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| Characterizing the Exhaust Plume of the Three-Electrode Micro Pulsed Plasma Thrusters |
Mar-2009 |
115 pages |
| Authors:
Seo Myeongkyo; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Three-electrode micro-PPTs are a new version of two electrode micro-PPTs devices. Performance predictions and contamination expectations are essential characteristics needed by satellite designers. In order to focus on thruster specific impulse, thrust and efficiency, measuring the exhaust velocity or impulse bit and propellant consumption rate is essential. While this is not always possible to measure directly, focusing on the ejected mass from the PPT provides significant information allowing determination of ... |
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| Mission Planning for Close-Proximity Satellites |
Mar-2009 |
70 pages |
| Authors:
Barry R Witt; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Given an initial orbit and a set of other orbits of interest, the lowest change in velocity path between them is of high value. Software was developed to visualize the change in velocity required from a user defined window of burn to a user defined window of intercept. The time between burn and intercept is unrestricted. Multiple intercepts require searching an n! solution space, research then is focused on ways ... |
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| Automated Detection of a Crossing Contact Based on Its Doppler Shift |
Mar-2009 |
117 pages |
| Authors:
Whye Kaong How; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The trade-off between false alarm and detection probability is a fundamental challenge in the automated detection of contacts in passive sonar systems. A common approach is the application of high gain processing followed by successive classification criteria. Most classification schemes (e.g., matching of signature) are complex and tailored to specific target types. By contrast, the Doppler effect is readily observed in all contacts with discrete tonals and relative velocity to ... |
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| The Distribution of Breaking and Non-Breaking Wave Impact Forces |
Mar-2009 |
40 pages |
| Authors:
Anne M Fullerton; Ann Marie Powers; Don C Walker; Susan Brewton; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD HYDROMECHANICS DIRECTORATE
|
| The magnitude of wave impact loads varies greatly, depending upon whether the wave is breaking, as well as on the wave height, length, steepness, and the geometry and immersion of the impacted structure. This report describes an experiment that was performed to characterize the distribution of breaking and non-breaking wave impact loads over a surface, similar to those performed in 2005 with non-breaking wave impact loads and those performed in ... |
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| Stochastic Analysis and Control of Transonic Helicopter Aerodynamics and Supersonic Projectiles |
02-Feb-2009 |
6 pages |
| Authors:
Sivaguru S Sritharan; WYOMING UNIV LARAMIE
|
| The main goal of this project is to develop a systematic mathematical theory for the robust real time feedback control and stochastic analysis of unsteady transonic aerodynamics of helicopter rotor blades, supersonic ballistic projectiles and propagation of blast waves in the presence of adverse external disturbances. The proposed work builds upon similar scientific advances by the principal investigator in the context of incompressible fluid dynamics, magneto-hydrodynamics and combustion models during ... |
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| Integrated Computational/Experimental Study of Turbulence Modification and Mixing Enhancement in Swirling Jets |
07-Jan-2009 |
30 pages |
| Authors:
J Naughton; D Stanescu; S Heinz; R Semaan; M Stoellinger; C Zemtsop; WYOMING UNIV LARAMIE
|
| Swirling jet flows have been studied experimentally and computationally and the results have been compared with theory. Three-component Laser Doppler Anemometry (LDA) measurements have been carried out for swirling jets of various strengths and swirl distributions. Radial profiles of velocity have been obtained from the jet exit to 50 diameters downstream. The experimental results are consistent with previous results and with similarity theory for weakly swirling turbulent jets. However, the ... |
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| Hydromagnetic Waves and Instabilities in Kappa Distribution Plasma |
Jan-2009 |
12 pages |
| Authors:
B Basu; AIR FORCE RESEARCH LAB HANSCOM AFB MA
|
| Stability properties of hydromagnetic waves (shear and compressional Alfven waves) in spatially homogeneous plasma are investigated when the equilibrium particle velocity distributions in both parallel and perpendicular directions (in reference to the ambient magnetic field) are modeled by kappa distributions. Analysis is presented for the limiting cases Xi alpha 1 and Xi alpha 1 for which solutions of the dispersion relations are analytically tractable. Here Xi alpha{a=e,i) is the ratio ... |
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| Effect of Variable Phase Transverse Acoustic Fields on Coaxial Jet Forced Spread Angles (Preprint) |
08-Dec-2008 |
35 pages |
| Authors:
Douglas Talley; Juan I Rodriguez; Ivett A Leyva; Jeffrey J Graham; AIR FORCE RESEARCH LAB EDWARDS AFB CA
|
| An experimental study on the effects of a variable phase transverse acoustic field on the inner jet spreading angle of a N2 shear coaxial jet at near critical pressures is presented. The jet spreading angle is an important parameter which characterizes the mixing between two flows. The transverse acoustic field is generated by two piezo-sirens which have a variable phase between them so the position of the jet with respect ... |
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| Testing and Evaluation of a Pen Input Device Using an Inertial/Magnetic Sensor Module |
Dec-2008 |
81 pages |
| Authors:
Leonidas Drakopoulos; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| In this thesis, the feasibility of developing a pen input device using an inertial/magnetic sensor module is investigated. The emphasis is on testing and evaluation of algorithms for computing handwriting trajectories based on accelerometer measurement data. This research starts by placing the inertial/magnetic sensor in a 2-D plane and writing alphanumeric characters. Before continuing to evaluate the 3-D writing, a calibration algorithm is implemented for computing the length between the ... |
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| Development and Testing of a New Area Search Model with Partially Overlapping Target and Searcher Patrol Areas |
Dec-2008 |
63 pages |
| Authors:
Gi Y Kim; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| In this study, the author uses a MATLAB simulation to develop and test a generalization of the traditional Random Search model which allows both the Search and target to move and to be in different, but overlapping, areas. Also the best evasion speed for a randomly moving target against a Systematic Search is studied. |
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| Hardware in the Loop Implementation of Adaptive Vision Based Guidance Law for Ground Target Tracking |
Dec-2008 |
109 pages |
| Authors:
Soh M L Bernard; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| An adaptive guidance law of a Vision Based Target Tracking (VBTT) system was previously developed and implemented onboard a Small Unmanned Aerial Vehicle (SUAV) in order to track a ground target moving with a constant velocity. This work extends previous results by considering scenarios where the variation of target velocity, in both magnitude and direction, is used to excite the feedback control law for further robustness analysis. This provides essential ... |
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