| Predicting Electron Transport Using Simulated Axial Waves in a Radial-Axial Hybrid Hall Thruster Model |
Sep-2009 |
12 pages |
| Authors:
Michelle K Scharfe; Mark A Cappelli; Eduardo Fernandez; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
|
 | Axial waves predicted by a two-dimensional hybrid numerical model have been used to estimate electron cross field transport due to tilted waves with azimuthal components. Since the radial-axial hybrid simulation cannot model these tilted waves directly, the predicted axial waves are assumed to couple symmetrically into two counter-propagating axial-azimuthal waves. A linearized two-dimensional dispersion relation is solved to obtain the azimuthal component of wavenumber consistent with the frequency and axial ... |
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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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| Duality and Unified Analysis of Discrete Approximations in Structural Dynamics and Wave Propagation: Comparison of rho-method Finite Elements with kappa-method NURBS (Preprint) |
10 OCT 2007 |
53 pages |
| Authors:
T. J. Hughes; A. Reali; G. Sangalli; TEXAS UNIV AT AUSTIN DEPT OF MTHEMATICS AND INST OF COMPUTATIONAL ENGINEERING AND SCIENCES
|
| We study the discretization behavior of classical finite element and NURBS approximations on problems of structural vibrations and wave propagation. We find that, on the basis of equal numbers of degrees-of-freedom and bandwidth, NURBS have superior approximation properties. In fact, we observe that the high mode behavior of classical finite elements is divergent with the order of approximation, a surprisingly negative result. On the other hand, NURBS offer almost spectral ... |
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| Analysis of Stability and Dispersion in a Finite Element Method for Debye and Lorentz Dispersive Media |
22 AUG 2006 |
74 pages |
| Authors:
H. T. Banks; V. A. Bokil; N. L. Gibson; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
|
| We study the stability properties of, and the phase error present in, a nite element scheme for Maxwell's equations coupled with Debye or Lorentz polarization. In one dimension we consider a second order formulation for the electric eld with an ordinary di erential equation for the polarization added as an auxiliary constraint. The nite element method uses linear nite elements in space for the electric eld as well as the ... |
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| Pulse Compression using a Tapered Microstructure Optical Fiber |
APR 2006 |
12 pages |
| Authors:
Jonathan Hu; Brain S. Marks; Curtis R. Menyuk; Jinchae Kim; Thomas F. Carruthers; Barbara M. Wright; Thierry F. Taunay; E. J. Friebele; MARYLAND UNIV BALTIMORE COUNTY BALTIMORE MD
|
| We calculate the pulse compression in a tapered microstructure optical fiber with four layers of holes. We show that the primary limitation on pulse compression is the loss due to mode leakage. As a fiber's diameter decreases due to the tapering, so does the air-hole diameter, and at a sufficiently small diameter the guided mode loss becomes unacceptably high. For the four-layer geometry we considered, a compression factor of 10 ... |
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| An Experimental Investigation of Guided Wave Propagation in Corrugated Plates Showing Stop Bands and Pass Bands (PREPRINT) |
FEB 2006 |
29 pages |
| Authors:
T. Kundu; S. Banerjee; Kumar V. Jata; ARIZONA UNIV TUCSON DEPT OF CIVIL ENGINEERING
|
| For health monitoring of structures with periodic geometry a good understanding of the elastic wave propagation through such periodic structures is necessary. Although a number of research papers on the wave propagation through periodic structures are available in the literature hardly anyone investigated experimentally the guided wave propagation through plates with periodic plate boundaries and compared the experimental data with theoretical predictions. In this paper the elastic wave propagation in ... |
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| Parameterizing the High Frequency Evolution of Nearshore Waves in a Nonlinear Wave Model |
07 OCT 2005 |
100 pages |
| Authors:
Kacey Edwards; Jayaram Veeramony; James Kaihatu; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Waves propagating through the shoaling and surf zones exhibit properties not characteristic of linear sinusoidal waves. Nonlinear wave-wave interactions act to transfer energy between the different harmonics of the peak frequency; this transfer is most apparent from the peak frequency of the spectrum to higher harmonics of the peak. As a result of these nonlinear interactions, the shape of a wave is altered making it asymmetrical vertically (skewness) and horizontally ... |
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| The Effect of Crowd Density on the Expected Number of Casualties in a Suicide Attack |
01-Jan-2005 |
9 pages |
| Authors:
Moshe Kress; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OPERATIONS RESEARCH
|
| Utilizing elementary geometric and probability considerations, the author estimates the effect of crowd blocking in suicide bombing events. It is shown that the effect is quite significant. Beyond a certain threshold, the expected number of casualties decreases with the number of people in the arena. The numerical results of the model are consistent with casualty data from suicide bombing events in Israel. Some operational insights are discussed. |
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| Effect of Ion-Parallel Viscosity on the Propagation of Alfven Surface Waves |
07 APR 2004 |
2 pages |
| Authors:
Nagendra Kumar; Himanshu Sikka; KGK(PG) COLL MORADABAD (INDIA) DEPT OFMATHEMATICS
|
| The paper analyzes the damping of the Alfven surface waves via ion parallel viscosity at a single magnetic interface. The dispersion relation is obtained and characteristics curves are drawn for the real and imaginary phase speeds. The modes thus obtained are two damped Alfven modes propagating in a way such that when one mode dies new mode appears after a certain propagation gap. The results are applicable for the situation ... |
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| Wave Propagation in Linear and Nonlinear Photonic Band-Gap Materials |
08 JUL 2003 |
11 pages |
| Authors:
Stephanos Venakides; DUKE UNIV DURHAM NC DEPT OF MATHEMATICS
|
| Numerical Codes and Analysis: Simulation and analysis of 2D resonant phenomena in photonic crystal slabs through the study of dispersion relations of bulk medium and surface waves along the crystal using the boundary integral method. Development of 3D boundary element code for EM scattering off photonic crystal slabs. Development of 2D FDTD code that includes nonlinearities and use in studying resonant phenomena. Nonlinear Effects: Derivation of the solution of the ... |
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| Turbulent and Mesoscale Flow in Stable Conditions |
20 JUN 2002 |
4 pages |
| Authors:
Larry Mahrt; OREGON STATE UNIV CORVALLIS COLL OF OCEANIC AND ATMOSPHERIC SCIENCES
|
| The structure of the nocturnal boundary layer has been examined using seven levels of eddy correlation data on the main tower in CASES99 data. Turbulence generated above the nocturnal surface layer and below the nocturnal jet intermittently bursts downward toward the surface This flow regime cannot be properly modeled within existing formulations. A z-less formulation of the transport is combined with a traditional model to improve simulation of these conditions. ... |
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| Eigensolution Analysis of the Discontinuous Galerkin Method with Non- uniform Grids, Part I: One Space Dimension |
DEC 2001 |
33 pages |
| Authors:
Fang Q. Hu; INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
|
| We present a detailed study of spatially propagating waves in a discontinuous Galerkin scheme applied to a system of linear hyperbolic equations. We start with an eigensolution analysis of the semi-discrete system in one space dimension with uniform grids. It is found that, for any given order of the basis functions, there are at most two spatially propagating numerical wave modes for each physical wave of the Partial Differential Equations ... |
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| Nearshore Airborne Lidar Observations |
08 AUG 2001 |
5 pages |
| Authors:
Alexandru Sheremet; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA OFFICE OF CONTRACT AND GRANT ADMINISTRATION
|
| Hwang et al. (1999a and 1999b) uses standard FFT procedures to estimate deep water 2-dimensional wavenumber spectra from lidar images. The characteristic wavelength analyzed is O(100m), homogeneity scale is O(10km) and wave evolution scale is O(100km). Knowledge of the local bathymetry allows, via the linear dispersion relation is needed for retrieving frequency-directional spectrum. The classical Fourier transform approach (FT) fails in the nearshore region due to the strong spatial inhomogeneities ... |
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| Birefringent Nanostructured Silicon: New Promising Material for Linear and Nonlinear Optics |
JUN 2001 |
|
| Authors:
D. Kovalev; V. Yu. Timoshenko; L. Golovan; E ; N. Kuenzner; TECHNICAL UNIV MUNICH (GERMANY) DEPT OF PHYSICS
|
 | Porous Si layers produced by anisotropic electrochemical etching of bulk Si exhibit strong in-plane birefringence which depends on the sizes of Si nanocrystals spacing between them and dielectric properties of their surrounding media. Second harmonic generation experiments have revealed phase matching conditions for wave interaction in the layers. Furthermore they can serve as a phase-matching matrix for optically nonlinear substance incorporated in their pores. This finding can significantly expand the ... |
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| Waves and Vibrations in Electroplated Piezoelectric Plates and Substrate Systems |
09 FEB 2001 |
5 pages |
| Authors:
Peter C. Lee; PRINCETON UNIV NJ DEPT OF CIVIL ENGINEERING AND OPERATIONS RESEARCH
|
| In the present research, a new, infinite system of plate equations is obtained. They are applicable to piezoelectric plates of any crystal symmetry and requiring no correction factors. Firstly, a system of first-order plate equations is extracted from the infinite system, and they are employed to study the thickness shear and flexure vibrations of rectangular plates of AT- and SC- cuts of quartz and are shown to give accurate predictions ... |
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| Space-Time Imaging of Shoaling Waves and Surf |
2001 |
5 pages |
| Authors:
John Dugan; Cindy Piotrowski; Zandy Williams; K. T. Holland; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| A fundamental barrier to consequential evaluation of modem, very capable shoaling wave and surf models has been the inability to provide high- quality ocean data with which to test model results. This paper describes a development intended to satisfy this need by providing space-time visible images of the nearshore from which three parameters crucial to such evaluations are simultaneously retrieved. These fields are the wave spectrum, bathymetry and currents. A ... |
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| Physiologically Based Pharmacokinetic Models for the Transport of Trichloroethylene in Adipose Tissue |
2001 |
28 pages |
| Authors:
R. A. Albanese; H. T. Banks; M. V. Evans; L. K. Potter; AIR FORCE RESEARCH LAB BROOKS AFB TX
|
| In this paper we present three physiologically based pharmacokinetic (PBPK) models for the systemic transport of trichloroethylene (TCE), with a focus on the adipose, or fat tissue. TCE is a widespread environmental contaminant, and has been shown to produce toxic effects in both animals and humans. A key characteristic of TCE is its tendency to accumulate in fat tissue, which has a major impact on the overall systemic disposition of ... |
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| Prototyping and Optimization of Ultra-High Speed Fiber Optic Links |
29 DEC 2000 |
5 pages |
| Authors:
Curtis R. Menyuk; MARYLAND UNIV BALTIMORE DEPT OF COMPUTER SCIENCE AND ELECTRICAL ENGINEERING
|
| The research was aimed at determining the impact of nonlinearity on the distribution of the differential group delay due to nonlinearity. And at determining the length scale over which polarization mode dispersion (PMD) yields the well-known asymptotic Maxwellian distribution. Professor Kath assisted with both projects. The work in both projects was presented at conferences and is being prepared for publication. In the first project, we simulated a large number of ... |
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| Surface Chemistry, Vibrational Dynamics, and Structural Stability of Metallic Interfaces |
12 OCT 2000 |
17 pages |
| Authors:
Steven J. Sibener; CHICAGO UNIV IL
|
| This research initiative explored the interactions of neutral particle, electron, and optical beams with well-characterized single crystal surfaces. These studies were motivated by the desire to understand and control surface reactions, such as surface oxidation/corrosion, the technological need to characterize the physical properties of thin films and surfaces, and the desire to understand how energy and momentum are exchanged at the surface of a ... |
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| Propagation of Energy Pulses in Absorbing/Viscous Material Media |
OCT 2000 |
13 pages |
| Authors:
G. C. Gaunaurd; G. C. Everstine; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| A delta-pulse that emerges from the origin of coordinates in a lossy, viscous, homogenes medium is studied as it propagates through the medium experiencing absorption and dispersion. Elementary models for such propagation problems have appeared in classical textbooks (e.g., J.D. Jackson, Classical Electrodynamics, pp. 212-215, Wiley, 1962). Generally speaking, as the pulse propagates, its amplitude decreases, and its width broadens. A more detailed, exact analysis of this problem emerges from ... |
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| Singular Guided Waves in a Chiroplasma |
29 SEP 2000 |
4 pages |
| Authors:
V. V. Fisanov; D. A. Marakassov; TOMSK STATE UNIV (RUSSIA)
|
| Waves with linearly distance-dependent amplitude (singular waves) directed by one and two plane boundaries in a chiroplasma are investigated for the Voigt geometrical configuration. Specially selected values of the chirality parameter give a transparent and an opaque version of the medium with twofold wave numbers for bulk eigenwaves. Dispersion relations are derived and solved with respect to electric or magnetic walls and an interface of two media. |
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| Nearshore Airborne Lidar Observations |
17 FEB 2000 |
5 pages |
| Authors:
Alexandru Sheremet; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA OFFICE OF CONTRACT AND GRANT ADMINISTRATION
|
| Hwang et al. (1999a and 1999b) uses standard FFT procedures to estimate deep water 2-dimensional wavenumber spectra from lidar images. The characteristic wavelength analyzed is O(100m), homogeneity scale is O(10km) and wave evolution scale is O(100km). Knowledge of the local bathymetry allows, via the linear dispersion relation, is needed for retrieving frequency-directional spectrum. The classical Fourier transform approach (FT) fails in the nearshore region ... |
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| Multi-Channel Data Acquisition System for Nondestructive Testing of Airbase Facilities |
08 MAY 1999 |
5 pages |
| Authors:
Glenn J. Rix; GEORGIA INST OF TECH ATLANTA SCHOOL OFCIVIL ENGINEERING
|
| A multi-channel data acquisition system including a variety of sources and receivers was purchased to support research at Georgia Tech aimed at the Air Force's need to develop innovative airbase technologies. The equipment purchased comprises a complete multi-channel system for acquiring, processing, analyzing, and displaying dynamic signals. The system provides the capability to more accurately and rapidly perform nondestructive tests, and has thus far been used on two research efforts ... |
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| Propagation Speeds of Ocean Surface Waves in Shallow Water |
MAR 1999 |
51 pages |
| Authors:
Nick A. Sarap Jr.; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Nonlinear effects on the dispersion relation of waves in shallow water are examined with measurements collected on a mild sloping sandy beach during the recent Sandy Duck experiment. Four arrays of bottom pressure sensors were deployed in depths ranging from 3 - 6 m during August-November, 1997. For each of these arrays, a root-mean-square average wavenumber was estimated as a function of frequency from the cross-spectra of one-hour-long pressure records. ... |
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| Propagation Speeds of Ocean Surface Waves in Shallow Water |
MAR 1999 |
51 pages |
| Authors:
Nick A. Sarap Jr.; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Nonlinear effects on the dispersion relation of waves in shallow water are examined with measurements collected on a mild sloping sandy beach during the recent Sandy Duck experiment. Four arrays of bottom pressure sensors were deployed in depths ranging from 3-6 m during August-November, 1997. For each of these arrays, a root-mean-square average wavenumber was estimated as a function of frequency from the cross-spectra of one-hour-long pressure records. The observed ... |
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| Ground Cloud Dispersion Measurements During The Titan IV Mission #K15 (5 December 1995) at Vandenberg Air Force Base. Volume 2 - Further Analysis of Quantitative Imagery and of Aircraft HCl Data |
12 MAY 1998 |
65 pages |
| Authors:
R. N. Abernathy; K. L. Foster; AEROSPACE CORP EL SEGUNDO CA TECHNOLOGY OPERATIONS
|
| The atmospheric dispersion Model Validation Program (MVP) collects and distributes launch cloud dispersion and transport data for the launch community. A previous report provided an overview and data summary for launch cloud measurements associated with the Titan IV Mission #K15 launch (5 December 1993). This report presents a more detailed analysis, both for the aircraft HCl measurements and for the quantitative imagery. This analysis includes a comparison, at one-min resolution, ... |
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| Validation of the Linear Dispersion Relation Using Field Observations |
02 MAR 98 |
26 pages |
| Authors:
K. T. Holland; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS MARINE GEOSCIENCES DIV
|
| The Naval Research Laboratory, working with representatives from the Naval Meteorology and Oceanography Command, the Naval Oceanographic Office, the Office of Naval Research, MEDEA, and MITRE, was tasked to investigate and validate two existing satellite remote sensing methods for determining bathymetry. Both of these methods utilize the linear, finite depth, dispersion equation for surface gravity waves to determine water depth from measurements of wave number magnitude as a function of ... |
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| Harmonic Millimeter Radiation from a Microwave Free Electron Laser Amplifier |
JUN 97 |
91 pages |
| Authors:
Yan-Hua Liu; COLUMBIA UNIV NEW YORK SCHOOL OF ENGINEERING AND APPLIED SCIENCE
|
| In this project an electron beam is bunched at a microwave frequency and the harmonics of this bunching drive radiation at millimeter wavelengths, using a FEL configured as a single pass traveling wave amplifier. A 10kW 24GHz microwave input signal grows to 200kW level using the lower frequency unstable root of the waveguide FEL dispersion relation. The Columbia FEL facility operates at this frequency in the TE11 mode, using a ... |
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| Dynamics of Gas-Surface Interactions |
15 JUN 96 |
59 pages |
| Authors:
Steven J. Sibener; CHICAGO UNIV IL
|
| A wide variety of gas-surface-and electron-surface scattering experiments, supported by lattice dynamics, molecular dynamics, and scattering calculations were carried out under the auspices of this grant. These studies were motivated by a desire to understand and control surface reactions, such as surface oxidation, the technological need to characterize the physical properties of thin films and surfaces, and the desire to understand how energy and momentum are exchanged at an interface ... |
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| Influence of Surface Roughness on Guided Waves in Plates |
30 APR 96 |
66 pages |
| Authors:
Dale E. Chimenti; Oleg I. Lobkis; IOWA STATE UNIV AMES CENTER FOR NONDESTRUCTIVE EVALUATION
|
| This report covers fundamental research performed on the effect of surface roughness on ultrasonic guided waves in plates. The effort reported here consists both of experiments and calculations. The measurements exploit guided waves generated in either immersion or with contact coupling. Samples have included aluminum prepared by indenting or sandblasting. The sandblasted specimens have been independently profiled to determine rms roughness. A simple model calculation is also described which, using ... |
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| The Interaction of UV-Laser Radiation with Metal and Semiconductor Surfaces |
04 AUG 95 |
61 pages |
| Authors:
Richard M. Osgood Jr; COLUMBIA UNIV NEW YORK MICROELECTRONICS SCIENCE LAB
|
| The first observations of image states on solid surfaces were reported about ten years ago using inverse photoemission and two-photon photoemission (2PPE), and the initial stages in the nonlinear spectroscopy of image states emphasized the measurement of the binding energies of these states as well as their dispersion relations or effective masses. More recently, work in this area has sought to exploit the relative precision of image-state spectroscopy by using ... |
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| The Interaction of Ultraviolet Laser Radiation with Metal and Semiconductor Surfaces |
04 AUG 95 |
60 pages |
| Authors:
Richard M. Osgood Jr; COLUMBIA RADIATION LAB NEW YORK
|
| The first observations of image states on solid surfaces were reported about ten years ago using inverse photoemission and two-photon photoemission (2PPE), and the initial stages in the nonlinear spectroscopy of image states emphasized the measurement of the binding energies of these states as well as their dispersion relations or effective masses. More recently, work in this area has sought to exploit the relative precision of image-state spectroscopy by using ... |
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| Wavelet Transform Signal Processing Applied to Ultrasonics |
MAY 95 |
29 pages |
| Authors:
A. Abbate; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| THE WAVELET TRANSFORM IS APPLIED TO THE ANALYSIS OF ULTRASONIC WAVES FOR IMPROVED SIGNAL DETECTION AND ANALYSIS OF THE SIGNALS. In instances where the mother wavelet is well defined, the wavelet transform has relative insensitivity to noise and does not need windowing. Peak detection of ultrasonic pulses using the wavelet transform is described and results show good detection even when large white noise was added. The use of the wavelet ... |
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| Numerical Studies of Turbulent Free Surface Flows and Unsteady Propeller Flows |
31 MAR 95 |
62 pages |
| Authors:
Steven A. Orszag; Vadim Borue; Ilya Staroselsky; Yansi Zhang; CAMBRIDGE HYDRODYNAMICS INC PRINCETON NJ
|
| Two main problems have been studied, viz. the structure of turbulence near a free surface and the Reynolds-averaged solution of unsteady propeller/ hydrofoil flows by the renormalization group (RNG) two-equation turbulence transport model. A variety of free-surface turbulence simulations demonstrate the key modifications in turbulence structure due to the free surface. In addition, we determine the modifications in surface wave spectra due to the turbulence beneath the free surface as ... |
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| Sensitivity of Stress and Boundary ImperfectIon of Dielectric Resonator Disks |
AUG 94 |
5 pages |
| Authors:
Peter C. Lee; PRINCETON UNIV NJ DEPT OF CIVIL ENGINEERING AND OPERATIONS RESEARCH
|
| The objective of the research is to Investigate (a) the sensitivity of the resonant frequencies of the dielectric disks under various applied forces and accelerations, and (b) the effect of the boundary imperfections of the dielectric disks on the resonances. The present research is a continuation of an ARO-supported project (DAAL 03-90-G-0079, 26909 MA). The research is conducted in two aspects: (1) for isotropic dielectrics and (2) for anisotropic dielectrics. ... |
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| The Effects of Altimeter Sampling Characteristics: Some Geosat Examples |
20 JAN 94 |
29 pages |
| Authors:
Michael E. Parke; George Born; COLORADO UNIV AT BOULDER
|
| Altimetric satellites have characteristic sampling patterns in both space and time. This paper looks at the distortions of oceanographic and atmospheric signals as seen in geosat altimeter data. Because of the pattern of ground tracks lain down by Geosat, measurements of oceanographic and atmospheric phenomena can be distorted spatially as well as temporally. As a result, phenomena measured by altimetric measurements can appear as propagating waves with both wavelength and ... |
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| The Acoustic and Instability Waves of Jets Confined Inside an Acoustically Lined Rectangular Duct |
DEC 93 |
31 pages |
| Authors:
Fang Q. Hu; INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
|
| An analysis of linear wave modes associated with supersonic jets confined inside an acoustically lined rectangular duct is presented. Mathematical formulations are given for the vortex-sheet model and continuous mean flow model of the jet flow profiles. Detailed dispersion relations of these waves in a two-dimensional confined jet as well as an unconfined free jet are computed. Effects of the confining duct and the liners on the jet instability and ... |
|
| The Effects of Altimeter Sampling Characteristics: Some Geosat Examples |
06 APR 93 |
29 pages |
| Authors:
Michael E. Parke; George Born; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| Altimetric satellites have characteristic sampling patterns in both space and time. This paper looks at the distortions of oceanographic and atmospheric signals as seen in geosat altimeter data. Because of the pattern of ground tracks lain down by Geosat, measurements of oceanographic and atmospheric phenomena can be distorted spatially as well as temporally. As a result, phenomena measured by altimetric measurements can appear as propagating waves with both wavelength and ... |
|
| Dynamics of Gas-Surface Interactions |
26 JAN 93 |
47 pages |
| Authors:
Steven J. Sibener; CHICAGO UNIV IL JAMES FRANCK INST
|
| This research initiative deals with the interaction of neutral particle, electron, and optical beams with well-characterized single crystal surfaces. These studies are motivated by a desire to understand and control surface reactions, such as surface oxidation, the technological need to characterize the physical properties of thin films and surfaces, and the desire to understand how energy and momentum are exchanged at the surface of a material when it is subjected ... |
|
| Development of a 500 GHz Optoelectronic Modulator Using Superconducting Transmission Lines |
31 AUG 92 |
29 pages |
| Authors:
Steven L. Williamson; John A. Nees; Gerard Mourou; MICHIGAN UNIV ANN ARBOR ULTRAFAST SCIENCE LAB
|
| This contract was set in place to investigate the technologies necessary to demonstrate multi-hundred-GHz modulation of optical signals. Techniques for eliminating velocity mismatch and modal dispersion, the two major limitations on state-of-the-art modulators, are presented. Further work to reduce signal distortion due to skin effect losses in normal conductors is detailed. Associated problems of interconnects and test instrumentation are also treated. Modulator, Detector, High-powered picosecond switching, Semiconductor Optical Temporal Analyzer ... |
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| Photonic Bloch Waves and Field Microstructure in Nonlinear Gratings: An Intuitive Approach, |
22 MAY 1992 |
|
| Authors:
P. St. J. Russell; SOUTHAMPTON UNIV (UNITED KINGDOM)
|
| Coupled wave theory is commonly used in numerical simulations of reflection from nonlinear grating structures. By contrast, the complementary photonic Bloch wave (PBW) approach has rarely been adopted, perhaps the only example being recent work on gap solitons. Bloch wave theory offers an alternative physical intuitive picture that encourages one to think in terms of field microstructure, leading to a range of simple explanations for the behaviour of light in ... |
|
| Large Non Resonant Nonlinearities in DANS Based Polymer Waveguide: Role of Microscopic Cascading, |
22 MAY 1992 |
|
| Authors:
Gaetano Assanto; George I. Stegeman; Manuel B. Marques; William E. Torruellas; UNIVERSITY OF CENTRAL FLORIDA ORLANDO CENTER FOR RESEARCH IN ELECTRO-OPTICS A ND LASERS
|
| Polymers can exhibit both large and fast nonresonant third-order nonlinearities which rely on Pi-electron delocalization and conjugation, as well as good physical and chemical properties suitable for the fabrication of nonlinear integrated optics devices. Soluble polymers with strong charge transfer states such asymmetrically substituted 4-dialkylamino-4'-nitro-stilbene (DANS) and 4-dialkylamino-4'-nitro-diphenylbu-tadiene (DAN2) side-groups were originally developed for electro-optic applications because of their large second order nonlinearities and low propagation losses in waveguide form. ... |
|
| Dynamic Effects of Kerr Nonlinearity and Spatial Diffraction on Self Phase Modulation of Optical Pulses, |
22 MAY 1992 |
|
| Authors:
M. Karlsson; D. Anderson; M. Desaix; M. Lisak; CHALMERS UNIV OF TECHNOLOGY GOETEBORG (SWEDEN)
|
| It is well known, cf that the optical Kerr effect can give rise to self focusing and is responsible for self phase modulation of optical pulses. The formal analogy between the phenomena of spatial diffraction and temporal dispersion of optical pulses was pointed out very early. However, only recently the two aspects have come together in the strong interest which has focussed on optical pulses propagating under the combined influence ... |
|
| OSA Proceedings of the Topical Meeting on Soft-X-Ray Projection Lithography Held in Monterey, California on 10-12 April 1991. Volume 12 |
22 MAY 92 |
158 pages |
| Authors:
Jeffrey Bokor; Jarus W. Quinn; OPTICAL SOCIETY OF AMERICA WASHINGTON DC
|
| The OSA Topical Meeting on Soft-X-Ray Projection Lithography was organized to bring together researchers working on these diverse issues. The meeting was held April 10-12, 1991, at the Monterey Conference Center in Monterey, California. As these proceedings show, significant progress is being made in all of the research fronts, but much remains to be done in order to overcome the difficult, yet exciting, challenges that lie ahead. A new approach ... |
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| Limitation for Transmission Capacity in Soliton Based Optical Fibre Communications Due to Stimulated Brillouin Scattering, |
22 MAY 1992 |
|
| Authors:
Carlos Montes; Alexander M. Rubenchik; NICE UNIV (FRANCE)
|
| For long-distance data communication based on coherent optical transmission in single-mode optical fibres, the use of soliton pulses as information carriers has raised a large interest since the NLS soliton concept (solution of the nonlinear Schroedinger equation) in dispersive optical fibres by Hasegawa and Tappert and its first experimental verification by Mollenauer. High bit rate transmission capacity may be achieved by this technique if the minimum distance between solitons (5 ... |
|
| Theory of Electromagnetic Instability of an Intense Beam in a Quadrupole Focusing System |
18 FEB 92 |
31 pages |
| Authors:
Cha-Mei Tang; J. Krall; T. Sywden; NAVAL RESEARCH LAB WASHINGTON DC
|
| Discrete quadrupole focusing system are subject to an electromagnetic instability wherein the growing transverse motion of the beam interacts with the quadrupole field and the TE sub 11 waveguide mode. The dispersion relation is derived, which is a matrix equation of infinite dimension. We show that an appropriately truncated matrix equation is able to give exact growth rates. Furthermore, analytical growth rates are obtained and instability boundaries are established. Numerical ... |
|
| Continuum Approaches for Describing Solid-Liquid Flow |
FEB 92 |
|
| Authors:
P. Diamond; J. Harvey; H. Levine; P. Steinhardt; R. Westervelt; MITRE CORP MCLEAN VA JASON PROGRAM OFFICE
|
| Two-phase continuum models have been used to describe the multiphase flow properties of solid-gas and solid-liquid mixtures. The approach is limited in that it requires many fitting functions and parameters to be determined empirically, and it does not provide natural explanations for some of the qualitative behavior of solid-fluid flow. In this report, we explore a more recent single-phase continuum model proposed by Jenkins and Savage (1982) to describe granular ... |
|
| Electromagnetic Instability of an Intense Beam in a Quadrupole Focusing System |
04 OCT 91 |
6 pages |
| Authors:
Cha-Mei Tang; Thomas Swyden; Jonathan Krall; NAVAL RESEARCH LAB WASHINGTON DC
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| Discrete quadrupole focusing systems are subject to the electromagnetic instability previously found in helical quadrupole strong focusing systems. The dispersion relation is derived. Analytical growth rates are obtained. Instability boundaries are established. Numerical solutions of the dispersion relation results show that the overall stability properties are not favorable for long pulse, high-current electron beams. |
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| III Potsdam-V Kiev International Workshop on Nonlinear Processes in Physics |
AUG 91 |
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| Authors:
A. S. Fokas; D. J. Kaup; A. C. Newell; V. E. Zakharov; CLARKSON UNIV POTSDAM NY DEPT OF MATHEMATICS AND COMPUTER SCIENCE
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| The III Potsdam-V Kiev Workshop on Nonlinear Processes in Physics was held at Clarkson University, Potsdam, NY from August 1-11, 1991. It was sponsored by the Clarkson School of Science and was funded by the National Science Foundation, the Department of Energy, the US Air Force of Scientific Research, the US Office of Naval Research, the Sloan Foundation and the School of Science of Clarkson University. The organizing committee was ... |
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| Acoustic Bloch Wave Propagation in a Periodic Waveguide |
24 JUL 91 |
110 pages |
| Authors:
Charles E. Bradley; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
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| The propagation of linear, dissipative acoustic Bloch waves in a periodic waveguide is investigated theoretically and experimentally. The waveguide under study is a rigid, fluid-filled, rectangular waveguide that is loaded with a periodic array of rigidly terminated rectangular side branches. Conditions for the existence of Bloch waves in the periodic waveguide are presented. Analytic expressions for the dispersion relation, the impedance function, and the Bloch wave function are derived. Measurements ... |
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Reports by Keyword(s)
DISPERSION RELATIONS
