| Near-Infrared Collisional Radiative Model for Xe Plasma Electrostatic Thrusters: The Role of Metastable Atoms |
Aug-2009 |
10 pages |
| Authors:
Yu-Hui Chiu; Rajesh Srivastava; Rainer A Dressler; Oleg Zatsarinny; Klaus Bartschat; Lalita Sharma; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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 | Metastable Xe atoms play an important role in the collisional radiative processes of dense xenon plasmas, including those of electric thrusters for space vehicles. Recent measurements and calculations of electron-excitation processes out of the metastable state have allowed for the development of a collisional radiative model for Xe near-infrared (NIR) emissions based on the population of the metastable level through radiative transitions, and based on depopulation through electron-impact excitation. A ... |
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| Limiting Impact Force Due to Yielding and Buckling of the Plates and Internal Structural Frame at the Bow of a Barge during Its Head-on Impact with a Bullnose or Cellular Structure |
Aug-2009 |
51 pages |
| Authors:
Robert M Ebeling; Terry W Warren; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS INFORMATION TECHNOLOGY LAB
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| This report presents a research study conducted to predict the impact forces that occur when a barge train impacts head-on with a circular concrete or concrete-filled structure. These structures are found at the end of lock approach walls as semicircles called bullnoses, as circular cells, and as mooring cells. This research was conducted using finite element analysis. A detailed finite element model of the bow of a jumbo hopper barge ... |
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| Economic Collision: Competition between the United States and China |
09-May-2009 |
30 pages |
| Authors:
Ruth A Neugebauer; ARMY WAR COLL CARLISLE BARRACKS PA
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| As China continues to rise on the international scene, competition between the United States and China becomes increasingly intense. This is true not only from a military perspective, but also from an economic one as China strives to become a global economic power. The competition has become more obvious recently due to the global economic recession and enormous fluctuations in natural resource commodity pricing over the past 12 months. China ... |
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| Probabilistic Estimation of Rare Random Collisions in 3 Space |
Mar-2009 |
92 pages |
| Authors:
Timothy Holzmann; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF OPERATIONAL SCIENCES
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| A study of risk assessment for artillery fire randomly colliding with fixed wing aircraft is presented. The research lends itself to a general study of collision models. Current models of object collisions fall under one of three categories: the historical model, the gas particle model, and the satellite model. These three vary in data requirements and mathematical representation of the impact event. The gas particle model is selected for its ... |
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| Atomistic Simulations of Hyperthermal Collisions Between Closed-Shell Species and Organic and Inorganic Surfaces |
Feb-2009 |
14 pages |
| Authors:
Diego Troya; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CHEMISTRY
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| This final report describes the efforts to develop computational- chemistry technology aimed at enabling simulation of gas/surface collisions of interest to the US Air Force that have been carried out under contract FA9550-06-1-0165. The report includes advances in three separate, but complementary lines of research that had the overarching goal of performing atomistic simulations of high-energy collisions between gases and surfaces with unprecedented levels of accuracy. These three lines are: ... |
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| Collisional Decoherence in Trapped-Atom Interferometers that use Nondegenerate Sources |
22-Jan-2009 |
9 pages |
| Authors:
Steven Miller; James A Stickney; Matthew B Squires; James Scoville; Paul Baker; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| The coherence time, and thus sensitivity, of trapped atom interferometers that use non-degenerate gases are limited by the collisions between the atoms. An analytic model that describes the effects of collisions between atoms in an interferometer is developed. It is then applied to an interferometer using a harmonically trapped non-degenerate atomic gas that is manipulated with a single set of standing wave laser pulses. The model is used to find ... |
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| Viewing Radiation Signatures of Solar Energetic Particles in Interplanetary Space |
Jan-2009 |
8 pages |
| Authors:
S W Kahler; B R Ragot; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| A current serious limitation on the studies of solar energetic particle (SEP) events is that their properties in the inner heliosphere are studied only through in situ spacecraft observations. Our understanding of spatial distributions and temporal variations of SEP events has come through statistical studies of many such events over several solar cycles. In contrast, flare SEPs in the solar corona can be imaged through their radiative and collisional interactions ... |
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| Exploring Structural Bond Energy Release (SBER) in Nanodiamonds Using Quantum Molecular Dynamics and Static High Pressure |
Dec-2008 |
8 pages |
| Authors:
Betsy M Rice; Jennifer A Ciezak; William D Mattson; Radhakrishnan Balu; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| We present a combined experimental and theoretical study on carbon nanodiamonds using Raman and DAC experimentation and ab initio calculations. Our calculations confirm the surface reconstruction to a fullerene-like structure, and indicate compression of the diamond core, producing an estimated internal pressure of 50 GPa. Quantum molecular dynamics simulations of hypervelocity collisions of NDs show that upon collision shock-induced amorphization first occurs, followed by complete disruption of the ND surface ... |
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| Seismic Tomography of the Arabian-Eurasian Collision Zone and Surrounding Areas |
30-Sep-2008 |
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| Authors:
Haijiang Zhang; M N Van der Toksoz; Robert D Hilst; Youshun Sun; Levent Gulen; Dogan Kalafat; Huseyin S Kuleli; Chang Li; MASSACHUSETTS INST OF TECH CAMBRIDGE
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 | The objectives of this study are to determine P- and S-wave velocity structures in the crust and upper mantle and to characterize seismic wave propagation in the Arabian-Eurasian collision zone and surrounding areas, including Iran, Arabia, Eastern Turkey, and the Caucasus. The Arabian-Eurasian plate boundary is a complex tectonic zone shaped by continent-continent collision processes. In recent years the number of seismic stations has increased greatly in the region because ... |
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| Temperature Dependences for the Reactions of O(-) and O(2-) with O(2)(a1-delta-g) from 200 to 700 K |
15-Jan-2008 |
7 pages |
| Authors:
A A Viggiano; Itzhak Dotan; Anthony Midey; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| Rate constants and product ion distributions for the O and O(2) reactions with 02(a delta g) were measured as a function of temperature from 200 to 700 K. The measurements were made in a selected ion flow tube (SIFT) using a newly calibrated 0:(a'As) emission detection scheme with a chemical singlet oxygen generator. The rate constant for the 02 reaction is 7 x 10(-10) cm(3) s(-1) at all temperatures, approaching ... |
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| Electron Impact Excitation Cross Sections of Xenon for Optical Plasma Diagnostic |
20 NOV 2007 |
21 pages |
| Authors:
Rajesh Srivastava; INDIAN INST OF TECH ROORKEE DEPT OF PHYSICS
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| In this project the researcher had taken up the calculation of xenon apparent emission-excitation cross sections for emission lines that have diagnostic value in the analysis of Xe-propelled electric thruster plasmas. Following conclusions were made from the study: The RDW method has been shown to be applicable to transitions between excited states. Since the excitation energy of these transitions is relatively small, first-order theories are valid at lower energies than ... |
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| Numerical and Experimental Investigation of Microchannel Flows with Rough Surfaces (Postprint) |
OCT 2007 |
10 pages |
| Authors:
T. C. Lilly; J. A. Duncan; S. L. Nothnagel; S. F. Gimelshein; N. E. Gimelshein; A. D. Ketsdever; I. J. Wysong; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| A conical surface roughness model applicable to particle simulations has been developed. The model has been experimentally validated for channel flows using helium and nitrogen gases at Reynolds numbers from 0.01 to 10 based on inlet conditions. To efficiently simulate gas-surface interaction, molecular collisions with the actual rough surface are simulated by collisions with a randomly positioned conical hole having a fixed opening angle. This model requires only one surface ... |
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| Biomechanics of North Atlantic Right Whale Bone: Mandibular Fracture as a Fatal Endpoint for Blunt Vessel-Whale Collision Modeling |
SEP 2007 |
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| Authors:
Regina P. Campbell-Malone; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| The North Atlantic right whale, Eubalaena glacialis, one of the most critically endangered whales in the world, is subject to high anthropogenic mortality. Vessel-whale collisions and entanglement in fishing gear were indicated in 27 (67.5%) of the 40 right whales necropsied between 1970 and December 2006. Of those, at least 9 deaths (22.5%) resulted from blunt contact with a vessel. To reduce the likelihood of fatal collisions, speed restrictions are ... |
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| Kinetics of Sulfur Oxide, Sulfur Fluoride, and Sulfur Oxyfluoride Anions with Atomic Species at 298 and 500 K |
FEB 2007 |
9 pages |
| Authors:
Anthony J. Midey; A. A. Viggiano; BOSTON COLL CHESTNUT HILL MA
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| The rate constants and product-ion branching ratios for the reactions of sulfur dioxide {SO2(-)}, sulfur fluoride {SF (n)-}, and sulfur oxyfluoride anions {SO(x)F(y)-} with H, H2, N, N2, NO, and 0 have been measured in a selected-ion flow tube (SIFT). H atoms were generated through a microwave discharge on a H2/He mixture, whereas O atoms were created via N atoms titrated with NO, where the N had been created by ... |
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| Seeking Radio Emissions from Hypervelocity Micrometeoroid Impacts: Early Experimental Results from the Ground |
15 NOV 2006 |
8 pages |
| Authors:
M. J. Starks; D. L. Cooke; B. K. Dichter; L. C. Chhabildas; W. D. Reinhart; III Thornhill T. F.; AIR FORCE RESEARCH LAB HANSCOM AFB MA
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| High-velocity impact experiments have been conducted to look for radio frequency (RF) emissions from impact-produced plasmas that could be used to identify micrometeoroid impacts to spacecraft in orbit. Launched by a three-stage light gas gun, 17 mm diameter by 0.9 mm thick Ti6Al-4V flyer plates impacted 0.75 mm thick indium (In) foil at more than 10 km s(-1). The resulting collision presumably ionized some fraction of the vaporized in cloud, ... |
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| Ultracold Atoms in Optical Lattices |
15 AUG 2006 |
63 pages |
| Authors:
Immanuel F. Bloch; LUDWIG-MAXIMILIANS UNIV MUNICH (GERMANY) SEKTION PHYSIK
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| This report results from a contract tasking Ludwig-Maximilian University of Munich as follows: The grantee will investigate controlled collisions between atoms in optical lattices production of strongly correlated quantum system with tunable internctions low dimensional degenerate quantum systems and rotating Bose-Einstein condensates in optical lattices -- observing the fractional Quantum Hall effect with bosons. |
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| Studies of Plasma Instabilities Excited by Ground-Based High Power HF (Heating) Facilities and of X and Gamma Ray Emission in Runaway Breakdown Processes |
AUG 2006 |
66 pages |
| Authors:
Aleksander V. Gurevich; RUSSIAN ACADEMY OF SCIENCES MOSCOW (RUSSIA) LEBEDEV INST
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| This report results from a contract tasking P. N. Lebedev Physical Institute as follows: The investigation will focus on how high power HF radio waves and quasistationary electric field interact with collisional plasmas, such as the earth's ionosphere or thunderstorm atmosphere. The aim of this proposal to investigate: 1. The interaction of Langmuir turbulence with surrounding ionospheric plasma determining kinetics of thermal and suprathermal electrons; 2. The optic emission of ... |
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| Multiple Usage of Existing Satellite Sensors |
JUL 2006 |
6 pages |
| Authors:
James T. Keeney; AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
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| Satellites in orbit are subjected to severe environmental extremes and an ever increasing risk of collision with resident space objects. Sensors are becoming necessary to observe and measure the proximity of a satellite to determine the risks posed from kinetically approaching manmade and natural hazards. Space offers a near-perfect vacuum to operate a passive or active sensor. Volume, mass and power on satellites is limited and risk management approaches tended ... |
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| O+HCl Cross Sections and Reaction Probabilities in DSMC (Postprint) |
JUL 2006 |
7 pages |
| Authors:
Takashi Ozawa; D. A. Levin; I. J. Wysong; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| A chemical reaction model, suitable for use in the Direct Simulation Monte Carlo (DSMC) method, is developed to simulate hypervelocity collisions of an important reaction in atmospheric-jet interactions. The model utilizes the Quasi-Classical Trajectory (QCT) method with two potential energy surfaces (PES), new benchmark triple surfaces and London-Eyring-Polanyi-Sato (LEPS) PES. The sensitivity of the flow to the fidelity of the chemical model is investigated for the new QCT-derived model and ... |
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| O+HCI Cross Sections and Reaction Probabilities in DSMC |
28 JUN 2006 |
7 pages |
| Authors:
Takashi Ozawa; D. A. Levin; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| A chemical reaction model, suitable for use in the Direct Simulation Monte Carlo (DSMC) method, is developed to simulate hypervelocity collisions of an important reaction in atmospheric-jet interactions ? O(3P)+HCI(1Σ+) → OH(2Π)+C1(2P). The model utilizes the Quasi-Classical Trajectory (QCT) method with two potential energy surfaces (PES), new benchmark triple A″ and A′ surfaces [1] and London-Eyring-Polanyi-Sato (LEPS) PES.[2] The sensitivity of the flow to the fidelity of the chemical model ... |
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| Investigation of Particle-in-Cell Acceleration Techniques for Plasma Simulations |
JUN 2006 |
23 pages |
| Authors:
David D. Marshall; Douglas B. VanGilder; CALIFORNIA POLYTECHNIC STATE UNIV SAN LUIS OBISPO
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| COLISEUM is an application framework that integrates plasma propagation schemes and arbitrary 3D surface geometries. Using Particle-in-Cell (PIC) schemes to model the plasma propagation high fidelity modeling of the plasma and its interaction with the surfaces is possible. In order to improve the computational performance of the Particle-in-Cell (PIC) scheme within COLISEUM (AQUILA), accelerate techniques have been developed that significantly decrease the amount of CPU time needed to obtain a ... |
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| Electron Attachment to POCl3: Measurement and Theoretical Analysis of Rate Constants and Branching Ratios as a Function of Gas Pressure and Temperature, Electron Temperature, and Electron Energy |
31 MAR 2006 |
10 pages |
| Authors:
Jane M. Van Doren; Jeffrey F. Friedman; Thomas M. Miller; A. A. Viggiano; S. Denifl; P. Scheier; T. D. Mark; J. Troe; AIR FORCE RESEARCH LAB HANSCOM AFB MA
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| Two experimental techniques, electron swarm and electron beam, have been applied to the problem of electron attachment to POCl3, with results indicating a competition between dissociation of the resonant POCl3 state and collisional stabilization of the parent anion. In the electron beam experiment at zero electron energy, the fragment ion POCl2- is the dominant ion product of attachment (96%) under single-collision conditions. Small amounts (~2% each) of POCl3- and Cl ... |
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| Dynamics of O(3P) Reactions with Gaseous Liquid and Solid Hydrocarbons |
MAR 2006 |
41 pages |
| Authors:
William L. Hase; TEXAS TECH UNIV LUBBOCK DEPT OF CHEMISTRY AND BIOCHEMISTRY
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| Prof. Hase has studied the reaction dynamics of oxygen atoms (triplet P state) with alkane hydrocarbons. In the initial phase, highly accurate ab initio quantum chemistry calculations (CASSCF, CASPT2, MRCI, with cc-pVTZ and cc-pVQZ basis sets) were applied to model reactions, including 0 + ethane and related reactions. In the second phase, a semiempirical quantum chemistry method, PM3-SRP, was developed by modifying and reparametrizing the standard PM3 method to fit ... |
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| Performance Analysis of a Cooperative Search Algorithm for Multiple Unmanned Aerial Vehicles under Limited Communication Conditions |
MAR 2006 |
138 pages |
| Authors:
Kevin M. Morris; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| This research investigates the impacts of realistic wireless communications upon a group of unmanned aerial vehicles (UAVs) utilizing a distributed search algorithm. The UAVs are used to survey an area for mobile targets and they require communication to cooperatively locate the targets. The mobile targets do not continually radiate energy, which exacerbates the search effort; a UAV could fly directly over a target and not detect it. A simulation of ... |
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| Theoretical Estimates of Reaction Observables vis-a-vis Modern Experiments |
08 FEB 2006 |
27 pages |
| Authors:
A. Lagana; PERUGIA UNIV (ITALY) DIPT DI CHIMICA
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| Recent advances in experimental chemical reaction dynamics are examined. The paper focuses on crossed beam technologies because the detailed single collision information they provide is a stringent test of the adopted molecular interaction. In this respect some prototypal atom-diatom and diatom-diatom elementary reactions are analysed. |
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| Solitonic Gateless Computing |
29 JAN 2006 |
90 pages |
| Authors:
George Stageman; Demetrios Christodoulides; Paul Prucnell; Mote Segev; Ken Squier; UNIVERSITY OF CENTRAL FLORIDA ORLANDO SCHOOL OF OPTICS/CREOL
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| A number of logic functions and mathematical operations were implemented in the laboratory based on soliton collisions in photo- refractive media. In addition to the usual NAND and AND logic gates, soliton collisions do transfer information and two successive collisions can be made to mimic a unitary matrix or its inverse. This program dictated and led developments in the field of soliton science and its applications. Its scientific impact was ... |
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| Multiple Usage of Existing Satellite Sensors (PREPRINT) |
2006 |
6 pages |
| Authors:
James T. Keeney; AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
|
| Satellites in orbit are subjected to severe environmental extremes and an ever increasing risk of collision with resident space objects. Sensors are becoming necessary to observe and measure the proximity of a satellite to determine the risks posed from kinetically approaching manmade and natural hazards. Space offers a near-perfect vacuum to operate a passive or active sensor. Volume, mass and power on satellites is limited and risk management approaches tended ... |
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| Passive Optical Diagnostic of Xe-Propelled Hall Thrusters. II. Collisional-Radiative Model |
2006 |
13 pages |
| Authors:
George F. Karabadzhak; Yu-Hui Chiu; Rainer A. Dressler; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| A collisional radiative model is presented for analyzing the xenon-propelled Hall Thruster optical radiation based on apparent electron and ion-impact emission cross sections associated with lines in the visible and near-infrared region of the spectrum. The emission cross sections of selected near-infrared emission lines are incorporated in a collisional-radiative model. The effect of Stepwise excitation via metastable states on the derived line intensities for emissions from XeI 5p56p(6p') levels is ... |
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| Simulation and Analysis of Dart Dispense Events with Collisions |
2006 |
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| Authors:
William E. Dietz; James Y. Baltar; Kevin Losser; Morris Morell; DIGITAL FUSION HUNTSVILLE AL
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| Current approaches to beach and surf zone mine clearance depend on the dispensing of large numbers of darts from a parent missile or projectile. The mine clearance mission requires a uniform distribution of darts over the target area. The dispersal pattern is affected by many factors, including the angle of attack, velocity, and rotational rate of the parent vehicle, the aerodynamic design of the darts, dart collision, and the different ... |
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| Collision Dynamics of Rydberg Atoms and Molecules at Ultralow Energies |
31 DEC 2005 |
108 pages |
| Authors:
M. R. Flannery; GEORGIA INST OF TECH ATLANTA SCHOOL OF PHYSICS
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| First Major Highlight: Collisional Stark Mixing at ultralow energies in Rydberg Plasmas. Atoms in high (n,l) states formed in cold Rydberg plasmas decay to the ground state in a succession of radiative transitions populating intermediate excited states. Which states are populated during cascading and with what probability can be obtained from known transition probabilities. Classical models simplify the calculation considerably, revealing the "trajectory" in nt space followed during the cascade, ... |
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| Structural Characterization of POSS Siloxane Dimer and Trimer (PREPRINT) |
14 NOV 2005 |
28 pages |
| Authors:
Timothy Haddad; Ashwani Vij; Stan Anderson; Connie Mitchell; Joseph Schwab; Mike Bowers; AIR FORCE RESEARCH LAB EDWARDS AFB CA
|
| Ion mobility and molecular modeling methods were used to examine the gas phase conformational properties of POSS (Polyhedral Oligomeric Silsesquioxanes) siloxane oligomers. MALDI generated the sodiated dimers (Cy7T8)2O Na+and (Cp7T8)2O Na+, and the trimer ion [Cy7T8O-Cy8Si8O11-OCy7T8] Na+ (T = SiO1.5, Cy = cyclohexyl, and Cp = cyclopentyl); their collision cross-sections were measured in helium using ion mobility based methods. Experimental results are consistent with one observed conformer for each of ... |
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| Quantum Lattice-Gas Model for Computational Fluid Dynamics |
28 SEP 2005 |
19 pages |
| Authors:
Jeffrey Yepez; AIR FORCE RESEARCH LAB HANSCOM AFB MA
|
| Quantum-computing ideas are applied to the practical and ubiquitous problem of fluid dynamics simulation. Hence, this paper addresses two separate areas of physics: quantum mechanics and fluid dynamics (or specifically, the computational simulation of fluid dynamics). The quantum algorithm is called a quantum lattice gas. An analytical treatment of the microscopic quantum lattice-gas system is carried out to predict its behavior at the mesoscopic scale. At the mesoscopic scale, a ... |
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| Rotational and Spin-Orbit Distributions of NO Observed by MIPAS/ENVISAT During the Solar Storm of October/November 2003 |
25 AUG 2005 |
10 pages |
| Authors:
J. L. Gardner; M. Lopez-Puertas; B. Funke; S. M. Miller; S. J. Lipson; R. D. Sharma; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| Aurorally enhanced 5.3 micrometer emission from nitric oxide was observed by the MIPAS instrument on board the ENVISAT satellite during the solar storm of October/November 2003. Spectral modeling of the NO(Delta nu = 1) fundamental band emissions was performed in order to determine the NO rotational and spin-orbit distributions. In the thermosphere, NO(nu = 1) is produced by collisional excitation of NO(nu = 0) by 0 atoms and also by ... |
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| Back Flux for Pulsed Laser Evaporation into Vacuum |
13 JUL 2005 |
7 pages |
| Authors:
Alexey A. Morozov; RUSSIAN ACADEMY OF SCIENCES NOVOSIBIRSK INST OF THERMOPHYSICS
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| This paper proposes results on calculation of the back flux for the case of pulsed laser evaporation into vacuum. On the basis of the direct Monte Carlo simulation, one-dimensional plane expansion of vapor cloud was calculated for a wide range of the number of evaporated monolayers. A substantial back flux rise is observed if the rotational degrees of freedom are taken into account. Influence of relaxation collision number on the ... |
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| DSMC Study of Shock-Detachment Process in Hypersonic Chemically Reacting Flow |
13 JUL 2005 |
7 pages |
| Authors:
Ye. A. Bondar; G. N. Markelov; S. F. Gimelshein; M. S. Ivanov; RUSSIAN ACADEMY OF SCIENCES NOVOSIBIRSK INST OF THEORETICAL AND APPLIED MECHANICS
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| Hypersonic chemically reacting flow around a wedge in the near-continuum regime was numerically studied by the DSMC method with the main goal of validation of real gas effect models. The influence of vibration-dissociation coupling on the results of numerical simulations was analyzed. To this end, two models of chemical reactions were used in the computations, the total collisional energy model and a vibrationally favored model. The numerical results were compared ... |
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| Ultracold Atoms in Optical Lattices |
11 JUL 2005 |
63 pages |
| Authors:
Immanuel F. Bloch; MUNICH UNIV (GERMANY F R)
|
| This report results from a contract tasking Ludwig-Maximillian University of Munich as follows: The grantee will investigate controlled collisions between atoms in optical lattices, production of strongly correlated quantum system with tunable interactions, low dimensional degenerate quantum systems, and rotating Bose-Einstein condensates in optical lattices -- observing the fractional Quantum Hall effect with bosons. |
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| C-17 Centerlining - Analysis of Paratrooper Trajectory |
JUN 2005 |
59 pages |
| Authors:
Waldemar F. Barnes; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The C-17's widebody design creates concern over its tendency to "centerline" paratroopers as they exit. This effect increases the probability of collision between jumpers from opposite sides of the aircraft. Previous work has been accomplished based on calculating the separation distance between trajectories and creating cumulative distributions of separation distances. This project focuses its analysis on the trajectories and any trends that can be seen over time, based on changing ... |
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| Computational Model of One-Dimensional Dielectric Barrier Discharges |
JUN 2005 |
111 pages |
| Authors:
Krista G. Marchand; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT/DEPT OF ENGINEERING PHYSICS
|
| A one-dimensional fluid model of a surface-type dielectric barrier discharge is created using He as the background gas. This simple model, which only considers ionizing collisions and recombination in the electropositive gas, creates an important framework for future studies into the origin of experimentally observed flow control effects of the DBD. The two methods employed in this study include the semi-implicit sequential algorithm and the fully implicit simultaneous algorithm. The ... |
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| Dilution of Disposal Orbit Collision Risk for the Medium Earth Orbit Constellations |
13 MAY 2005 |
39 pages |
| Authors:
A. B. Jenkin; R. A. Gick; AEROSPACE CORP EL SEGUNDO CA
|
| Previous studies have shown that disposal orbits for the medium Earth orbit constellations can be unstable and undergo significant long-term eccentricity growth. This can lead to repenetration of the constellations by disposed vehicles, thereby posing a collision risk. The study presented here investigated the possibility of diluting disposal orbit collision risk by exploiting long-term eccentricity growth. The Galileo constellation was selected as an example. Various disposal strategies were considered. It ... |
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| Hybrid Gas/Plasma Simulations Using DSMC with the VORPAL Code |
MAY 2005 |
14 pages |
| Authors:
Wen-Lan Wang; Chet Nieter; Peter Stoltz; Jean-Luc Cambier; TECH-X CORP BOULDER CO
|
| We are adding a Direct Simulation Monte Carlo model to the plasma simulations code VORPAL to model dilute (large Knudsen number) gases. This will allow VORPAL to run hybrid simulations of gas/plasma mixtures using the current plasma simulation capabilities of VORPAL along with the newly added DSMC capabilities. VORPAL is a multidimensional, parallel Particle-in-Cell plasma simulation code that supports a variety of models for both the plasma and electromagnetic fields. ... |
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| Maneuver Estimation Model for Relative Orbit Determination |
21 MAR 2005 |
77 pages |
| Authors:
Tara R. Storch; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| While the use of relative orbit determination has reduced the difficulties inherent in tracking geosynchronous satellites that are in close proximity, the problem is often compounded by stationkeeping operations or unexpected maneuvers. If a maneuver occurs, observations will no longer fit predicted data, increasing the risk of misidentification and cross-tagging. The goal of this research was to develop a model that will estimate the magnitude, direction, and time of a ... |
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| Bioreactor Based Bone Tissue Engineering: Influence of Wall Collision on Osteoblast Cultured on Polymeric Microcarrier Scaffolds in Rotating Bioreactors |
2005 |
6 pages |
| Authors:
Xiaojun Yu; Edward A. Botchwey; Elliot M. Levine; Soloman R. Pollack; Cato T. Laurencin; VIRGINIA UNIV CHARLOTTESVILLE DEPT OF CHEMICAL ENGINEERING
|
| Rotating bioreactors have been used to overcome the limitations of passive nutrient diffusion in three-dimensional (3D) constructs for tissue engineering of bone. It is hypothesized that conventional scaffolds undergo repeated wall collisions in rotating bioreactors, which may disrupt bone tissue formation. In this study, we investigated the effects of wall collision on osteoblastic cells cultured on a microsphere based scaffold of varying densities in comparison to water. The conventional heavier ... |
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| Dissociative Recombination Study of Na(+) (D2O) in a Storage Ring |
01 DEC 2004 |
7 pages |
| Authors:
Vitali Zhaunerchyk; Anneli Ehlerding; Wolf D. Geppert; Fredrik Hellberg; Richard D. Thomas; Mats Larsson; Albert A. Viggiano; Susan T. Arnold; Fabian Oesterdahl; STOCKHOLM UNIV (SWEDEN) INST OF PHYSICS
|
| The dissociative recombination of Na(+) (D2O) ion has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). The cross section has been measured as a function of center-of-mass energy ranging from 1 meV to 0.1 eV and found to have an E (sup -1.37) dependence. The rate coefficient has been deduced to be (2.3 +/- 0.32) X 10(exp -7) x T(sub e/300)(exp -0.95 +/- 0.01)cu cm ... |
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| On Plasma Sheath Resonant Energy Absorption in Collisionless Plasmas |
19 OCT 2004 |
16 pages |
| Authors:
David N. Walker; WIlliam E. Amatucci; Richard F. Fernsler; David D. Blackwell; Sarah J. Messert; NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV
|
| We have performed experiments designed to investigate the radiation characteristics of a spherical capacitive probe in a plasma environment in the large Space Physics Simulation Chamber at the Naval Research Laboratory. In the process we are able to approximate plasma density and electron neutral collision frequency in simulated space plasma environments consistent with earlier experimental efforts using plasma impedance probes. By using only the S(sub 11)- parameter outputs of a ... |
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| Reactions of N(+), N2(+), and N3(+) with NO From 300 to 1400 K |
08 OCT 2004 |
9 pages |
| Authors:
Anthony J. Midey; Thomas M. Miller; A. A. Viggiano; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| Rate constants have been measured from 300 to 1400 K in a selected ion flow tube (SIFT) and a high temperature flowing afterglow for the reactions of N(+), N2(+) and N3(+) with NO. In all of the systems, the rate constants are substantially less than the collision rate constant. Comparing the high temperature results to kinetics studies as a function of translational energy show that all types of energy (translational, ... |
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| Broadband Plasma Impedance Measurements and Determination of Plasma Parameters |
20 SEP 2004 |
12 pages |
| Authors:
WIlliam E. Amatucci; David N. Walker; David D. Blackwell; NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV
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| A small spherical probe is used in conjunction with a network analyzer to determine the impedance of the probe-plasma system over a wide frequency range. Impedance curves are in good agreement with accepted circuit modes with plasma-sheath and electron plasma frequency resonances easily identifiable. Phase measurements show clear transitions between capacitive and inductive modes as predicted by the model. Sheath thickness and absolute electron density are determined from the location ... |
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| Cooling and Trapping of Atoms and Particles |
AUG 2004 |
11 pages |
| Authors:
Steven Chu; STANFORD UNIV CA BOARD OF TRUSTEES
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| In this work, we report a summary of the more than 60 magnetic field- induced Feshbach resonances in ultracold collisions of ground-state cesium atoms. The detection is based on elastic, inelastic and radiative collision processes. The observations have allowed us to improve upon the interaction potentials between cesium atoms, which, in turn, allowed us to predict the possible magnetic field regions where the Bose condensation of cesium atoms would be ... |
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| Quantum and Quasi-Classical Studies of the O(3P) + HCl yields OH + Cl(2P) Reaction Using Benchmark Potential Surfaces (PREPRINT) |
25 JUL 2004 |
39 pages |
| Authors:
Tiao Xie; Joel Bowman; J. W. Duff; M. Braunstein; B. Ramachandran; EMORY UNIV ATLANTA GA DEPT OF CHEMISTRY
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| We have performed quantum mechanical (QM) dynamics calculations within the independent-state approximation with new benchmark triplet A" and A' surfaces [B. Ramachandran et al. J. Chem. Phys. 119, 9590 (2003).] for the ro-vibronic state-to-state measurements of the reaction O(3P) + HCl(v=2,j=1,6,9) OH(v j ) + Cl(2P) [Zhang et al. J. Chem. Phys. 94, 2704 (1991)]. The QM and experimental rotational distributions peak at similar OH(j ) levels, but the ... |
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| Reactions of O(+) With C(n)H(2n+2), n=2-4: A Guided-Ion Beam Study |
15 APR 2004 |
10 pages |
| Authors:
D. J. Levandier; Y. Chiu; R. A. Dressler; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| We have measured absolute reaction cross sections for the interaction of 0+ with ethane, propane, and n-butane at collision energies in the range from near thermal to approximately 20 eV, using the guided-ion beam (GIB) technique. We have also measured product recoil velocity distributions using the GIB time- of-flight (TOF) technique for several product ions at a series of collision energies. The total cross sections for each alkane are in ... |
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| Plasma Channel Dynamics Created by High-Current Relativistic Electron Beam When Being Distributed in Gaseous Media of Various Types |
07 APR 2004 |
2 pages |
| Authors:
N. A. Kondratiev; G. E. Remnev; V. I. Smetanin; TOMSK POLYTECHNIC UNIV (RUSSIA) NUCLEAR PHYSICS INST
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| Experimental results of determination of plasma channel dynamics created by high-current beam (energy of electrons E(sub e) =1,1 x 10(exp 6) eV, beam current I(sub b)=2,4 x 10(exp 4) A, with pulse duration t=60 x 10(exp -9) c.) in gases: helium (He), nitrogen (N(sub 2)), neon (Ne), Air (Air),argon (Ar), krypton (Kr), xenon (Xe), humid air (Air:water) at pressure from 1 to 760 Tor are presented. It is showed that ... |
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