| Comparison of DSMC Predictions and Experimental Flowfield Measurements in Vaccum Plume Expansions, |
FEB 1993 |
|
| Authors:
I. J. Wysong; D. H. Campbell; D. P. Weaver; DAYTON UNIV EDWARDS AFB CA RESEARCH INST
|
 | Experimental verifications of the Direct Simulation Monte Carlo (DSMC) technique are needed in order to reliably predict high-altitude rocket exhaust plume signatures in the rarefied regime. Nonequilibrium effects are critical at high altitude, requiring a verified particle simulation model for both elastic and inelastic collisions. We report the first results of a new effort to compare DSMC calculations of cold plume expansion flows with experimental measurements. Laser-induced fluorescence (LIF) is ... |
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| 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 ... |
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| Energy Exchange between Surface and Internal Waves; Soliton-Like Wave- Packets in the Wake of a Ship; Excitation and Generation of Short Capillary Waves by Longer Waves |
JAN 93 |
6 pages |
| Authors:
Kenneth M. Watson; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB
|
| We have shown that an energy transfer of the order of 10(exp 4) Omega/sq m can occur between surface and internal waves. The transfer is predominantely from the internal to the surface waves, but it can go either way, depending on the Vaisala frequency profile and the surface wave spectrum. We are putting together a database of wind and Vaisala profiles for the North Pacific in order to evaluate the ... |
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| Energy Transfer Studies in Interhalogen Molecules |
JAN 93 |
59 pages |
| Authors:
S. J. Davis; K. W. Holtzclaw; W. J. Kessler; L. G. Piper; PHYSICAL SCIENCES INC ANDOVER MA
|
| This program is examining energy transfer processes in interhalogen molecules that have potential for visible chemical laser development. Spectrally resolved laser induced fluorescence is used to determine rotation-to-translation (R-T) and vibration-to-translation (V-T) rate coefficients. In this report we compare several fitting laws for R-T transfer to data obtained for IF and IC1 interactions with several collision partners. We have also obtained preliminary data on V-T relaxation within the ground electronic ... |
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| The Effect of the March 1991 Storm on Accumulated Dose for Selected Satellite Orbits: CRRES Dose Models |
DEC 1992 |
9 pages |
| Authors:
M. S. Gussenhoven; E. G. Mullen; Michele Sperry; K. J. Kerns; PHILLIPS LAB HANSCOM AFB MA
|
| Three dose models are constructed using direct measurements of dose on the CRRES satellite, in a low-inclination, geosynchronous-transfer orbit. The Average Model uses data taken over the entire 14 months of the CRRES mission from July 1990 to October 1991. The Quiet Model uses data from July 1990 to March 1991. The Active Model uses data from March 1991 to October 1991. The separation of the quiet and active periods ... |
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| Progress in Impulse Approach Research |
30 OCT 92 |
108 pages |
| Authors:
H. Dothe; J. M. Sindoni; YAP ANALYTICS INC LEXINGTON MA
|
| This report entails the progress made during the first contract year in the research of Impulse Approach (IA) modeling. The IA technique was successfully applied to the Ar-CsF scattering system with results that compared favorably with observations. Limitations and discrepancies were also found in the treatment of other scattering systems which were attributed to the confinement of the IA method to the single collision T matrix. Work is at the ... |
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| Ultrafast Frequency Agile Optical Materials: Organically Doped Sol-Gel Glasses |
14 OCT 92 |
19 pages |
| Authors:
Eric L. Chronister; CALIFORNIA UNIV RIVERSIDE
|
| This report focuses on organically doped sol-gel glasses as novel fast response photochromic materials. In particular, we discuss time-resolved spectroscopic measurements of: (1) nanosecond optical energy transfer in organically doped glasses; (2) investigation of the spatial distribution of chromophores within the porous sol-gel matrix; (3) homogeneous dephasing of optically excited states as a probe of chromophore-host interactions; (4) time- resolved anisotropy measurements as a probe of chromophore dynamics in porous ... |
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| Reactions and Spectroscopy of Excited Nitrenes |
05 OCT 92 |
29 pages |
| Authors:
Robert D. Coombe; COLORADO SEMINARY DENVER
|
| This report describes progress made on the research program 'Reactions and Spectroscopy of Excited Nitrenes' during the eighteen month period between 1 July, 1990 and 31 December, 1991. The broad objectives of the program include defining new means for the generation of halogen nitrene metastables, measuring the properties of processes by which these metastables transfer the energy they carry to laser candidate species, and probing the kinetics and mechanisms of ... |
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| Flexible Sheet Explosive. |
22 SEP 1992 |
|
| Authors:
Vernon D. Ringbloom; Matthew O. Savage; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| An explosive device and process of using same is provided to exert a desired force on an object without exposure to the flame heat generated upon detonation of explosive charge sandwiched between protective layers of a protective casing. One of the layers is of a thickness sufficient to absorb substantially all of the explosive released thermal energy but sufficiently thin to transfer the kinetic energy associated with the desired force ... |
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| An Experimental Examination of the Thermal and Acoustic Environments on Runway Joint Seals |
SEP 92 |
107 pages |
| Authors:
E. E. Cooper; C. Dahl; NAVAL CIVIL ENGINEERING LAB PORT HUENEME CA
|
| A test series was conducted at Edwards Air Force Base to determine noise and temperature environments that joint seal materials experience on an operational runway. Impingement of exhaust flow from jet engines creates an aerothermal environment for joint seal materials that contributes to, and accelerates, the deterioration and failure of joint seals. The aerothermal environment consists of noise (considered in this report as acoustically-induced as well as flow-induced fluctuations) and ... |
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| Extension of Fresnel Near-Field Region by Single-Cycle Sinusoidal Pulses |
21 AUG 92 |
56 pages |
| Authors:
S. N. Samaddar; NAVAL RESEARCH LAB WASHINGTON DC
|
| A circular conducting disk antenna is excited by three uniform current waveforms namely, a very high frequency CW sin& , a single-cycle sinwO1, and a single-cycle coswOt. The energy per cycle associated with each of these waveform is taken to be the uM. From the behavior of the radiated energy densities along the axis of the disk, it is found that if the CW waveform extends the near field to ... |
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| OH Alpha 2Sigma(+) Yields Chi 2Pi Chemiluminescence Measurements of Nsub2(+), Ar(+) + Hsub2O Hydrogen-Atom-Transfer Reactions at Suprathermal Energies |
15 AUG 1992 |
10 pages |
| Authors:
James A. Gardner; Rainer A. Dressler; Richard H. Salter; Edmond Murad; PHILLIPS LAB HANSCOM AFB MA
|
| Chemiluminescence attributable to OH Alpha 2Sigma(+) yields Chi 2Pi emission is observed in hydrogen-atom transfer reactions of Nsub2(+) and Ar(+) with Hsub2O. High-resolution OH Alpha yields Chi spectra (0.5 nm full width at half maximum (FWHM)) are presented as a function of collision energy in the range Esubc.m. = 5-20 eV. The spectra clearly show an increase in rotational broadening with collision energy. To reasonably fit the spectral data, simulations ... |
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| Laser Doppler Measurements of a Grid-Generated Turbulence Undergoing a Volume Reduction, |
23 JUL 1992 |
|
| Authors:
G. Serre; L. Le Penven; ECOLE CENTRALE DE LYON ECULLY (FRANCE)
|
| An homogeneous turbulent flow submitted to a uniform compression is investigated using LDV. The initial turbulent flow which is produced by drawing a grid in a closed cylinder is compressed by means of a piston. Ensemble averaging is used to compute velocity moments. The experimental set-up specially designed for this purpose is described. Preliminary results are given including; compression without initial flow, free decay of grid-generated turbulence and combination of ... |
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| Bevalac Ion Beam Characterizations for Single Event Phenomena |
16 JUL 92 |
23 pages |
| Authors:
R. Koga; N. Katz; S. D. Pinkerton; W. A. Kolasinski; D. L. Oberg; AEROSPACE CORP EL SEGUNDO CA SPACE AND ENVIRONMENTAL TECHNOLOGY CENTER
|
| Linear Energy Transfer (LET) distributions of Bevalac ion beams were measured. Subsequent analysis has called into question the standard assumption of a monoenergetic, single-species beam at Bevalac. Both high LET contaminants in the primary beam and very broad LET peaks in degraded beams were observed. High energy ion beams at other accelerators may possess similar characteristics. The existence of beam impurities may have important ramifications for the interpretation of single-event ... |
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| Comparison of Heavy Ion and Electron-Beam Upset Data for GaAs SRAMs |
16 JUL 92 |
19 pages |
| Authors:
L. D. Flesner; R. Zuleeg; W. A. Kolasinski; AEROSPACE CORP EL SEGUNDO CA ENGINEERING AND TECHNOLOGY GROUP
|
| We report the results of experiments designed to evaluate the extent to which focused electron-beam pulses simulate energetic ion upset phenomena in GaAs memory circuits fabricated by the McDonnell Douglas Astronautics Company. The results of two experimental methods were compared, irradiation by heavy-ion particle beams, and upset mapping using focused electron pulses. Linear energy transfer (LET) thresholds and upset cross sections are derived from the data for both methods. A ... |
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| Bevalac Ion Beam Characterizations for Single Event Phenomena |
16 JUL 92 |
20 pages |
| Authors:
R. Koga; N. Katz; S. D. Pinkerton; W. A. Kolasinski; D. L. Oberg; AEROSPACE CORP EL SEGUNDO CA ENGINEERING AND TECHNOLOGY GROUP
|
| Linear Energy Transfer (LET) distributions of Bevalac ion beams were measured. Subsequent analysis has called into question the standard assumption of a monoenergetic, single-species beam at Bevalac. Both high LET contaminants in the primary beam and very broad LET peaks in degraded beams were observed. High energy ion beams at other accelerators may possess similar characteristics. The existence of beam impurities may have important ramifications for the interpretation of single-event ... |
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| Electromagnetic Momentum Density and Radiation Pressure in Normally Dispersive, Non-Dispersive Media |
06 JUL 92 |
64 pages |
| Authors:
Francis S. Johnson; Bruce L. Cragin; R. R. Hodges; TEXAS UNIV AT DALLAS RICHARDSON
|
| Consideration of the electromagnetic momentum density D x B associated with a parallel plate capacitor in the presence of a magnetic field parallel to the plates shows that the momentum is a property of the electromagnetic field in a dielectric (closely related to the polarization of the dielectric) rather than a matter of storing mechanical momentum in the dielectric. This has implications regarding transport of momentum by electromagnetic waves. The ... |
|
| A Proposal to Produce Velocity-Selected and State-Selected Molecular Beams Using the Ballistic Effect |
01-Jul-1992 |
4 pages |
| Authors:
J M Sindoni; R D Sharma; YAP ANALYTICS INC LEXINGTON MA
|
| A method for producing molecular beams containing molecules in the desired internal (rotational, vibrational, electronic, etc.) state and traveling with the desired velocity is proposed. The method is illustrated by describing the circumstances that would lead to a state-selected and velocity-selected N(sub 2) beam resulting from collisions with Li(+) with N(sub 2). |
|
| Non-Local Thermodynamic Equilibrium in Laser Sustained Plasmas |
16 JUN 92 |
208 pages |
| Authors:
D. Zerkle; H. Krier; ILLINOIS UNIV AT URBANA DEPT OF MECHANICAL AND INDUSTRIAL ENGINEERING
|
| An argon laser sustained plasma (LSP) at atmospheric pressure has been studied spectroscopically and the existence of a non-local thermodynamic state has been determined. The spectroscopic data consist of several argon neutral and ion line emissions used to spatially resolve electronic energy level population densities in each plasma species. A hydrogen seed is added to the argon flow for the purpose of determining electron number density by Stark broadening analysis ... |
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| On the Effects of Horizontal Resolution in a Limited-Area Model of the Gulf Stream System |
02 JUN 1992 |
|
| Authors:
William J. Schmitz Jr.; J. D. Thompson; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| An adiabatic, primitive equation, eddy-resolving circulation model has been applied to the Gulf Stream System from Cape Hatteras to east of the Grand Banks (30 deg -48 deg N, 78 deg -45 deg W). A two-layer version of the model was driven both by direct wind forcing and by transport prescribed at inflow ports south of Cape Hatteras for the Gulf Stream and near the Grand Banks of Newfoundland for ... |
|
| Photodynamics within (CH3OH)nCr(CO)6 Heteroclusters: Observation of an Isotope Effect |
01 JUN 92 |
24 pages |
| Authors:
William R. Peifer; James F. Garvey; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| We have recently examined the multiphoton dissociation and ionization dynamics of mixed van der Waals heteroclusters of Cr(CO)6 solvated by methanol, and have inferred from photoion fragmentation branching ratios that CD30D is more efficient than CH30H in relaxing excess internal energy of the nascent photoion via intracluster energy transfer. Multiphoton ionization is suggested to proceed via single photon photodissociation of the solvated Cr(CO)6, followed by two-photon ionization of the coordinatively ... |
|
| New Applications of Ionization and Fluorescence Techniques for Detecting and Characterization of Open-Shell Organometallics in the Gas Phase |
01 JUN 92 |
32 pages |
| Authors:
William R. Peifer; Robert L. DeLeon; James F. Garvey; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| Recent advances are discussed in the development of electronic spectroscopic probes for the study of excited-state structure and photodissociation dynamics of gas-phase organometallics. Because of the short time - scale for intermolecular energy transfer within van der Waals clusters, the UV photodissociation dynamics of cluster-bound transition metal carbonyls differs considerably from the photodissociation dynamics of the naked species in the gas phase. It is therefore possible to employ multiphoton ionization ... |
|
| Investigation of the Dynamics of Low-Tension Cables |
JUN 92 |
|
| Authors:
Christopher T. Howell; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| Low-tension cable problems are particularly complex as linear solutions are unobtainable in most cases, due to the lack of a meaningful static configuration. By contrast, the dynamics of taut cables are only weakly nonlinear. First, the three-dimensional nonlinear equations of motion and compatibility relations are formulated for a cable with bending stiffness. Forces in bending are included to provide the necessary physical mechanism for energy transfer across isolated points of ... |
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| New Applications of Ionization and Fluorescence Techniques for Detecting and Characterization of Open-Shell Organometallics in the Gas Phase |
29 MAY 92 |
31 pages |
| Authors:
William R. Peifer; Robert L. DeLeon; James F. Garvey; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| Recent advances are discussed in the development of electronic spectroscopic probes for the study of excited-state structure and photodissociation dynamics of gas-phase organometallics. Because of the short timescale for intermolecular energy transfer within van der Waals clusters, the UV photodissociation dynamics of cluster-bound transition metal carbonyls differs considerably from the photodissociation dynamics of the naked species in the gas phase. It is therefore possible to employ multiphoton ionization to produce ... |
|
| Ionization of a High Energy Neutral Beam Propagating in the Ionosphere |
26 MAY 1992 |
7 pages |
| Authors:
Shu T. Lai; PHILLIPS LAB HANSCOM AFB MA
|
| By using modeled stripping ionization cross sections and standard atmospheric density models, we calculate stripping ionization probability of high energy (MeV) neutral beams propagating in the earth's atmosphere. Numerical results as functions of altitude, beam angle and beam energy are presented. We also consider Alfven's critical ionization velocity (CIV) process as an alternate ionization pathway. If CIV occurs as the neutral beam propagates through the geoplasma across the ambient magnetic ... |
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| Two-Beam Coupling with Partially Coherent Light, |
22 MAY 1992 |
|
| Authors:
Hongzhi Kong; Wieslaw Krolikowski; Mark Cronin-Golomb; TUFTS UNIV MEDFORD MA ELECTRO-OPTICS TECHNOLOGY CENTER
|
| In photorefractive two-beam coupling the interference of two optical beams creates a refractive index grating resulting in energy transfer between the two beams. In models describing this effect it is usually assumed that both beams have perfect spatial coherence. For some applications such as achromatic volume, holography, multimode fiber gyroscopes and optical phase conjugation through turbulence, spatial coherence effects may become important in the coupling process. Reduced spatial coherence leads ... |
|
| Application of Beam Fanning in a Photorefractive BaTiO sub 3 Crystal: Measurement of Light Scattering at Zero Degrees by a Single Glass Fiber, |
22 MAY 1992 |
|
| Authors:
G. G. Padmabandu; Choonghoon Oh; Edward S. Fry; TEXAS A AND M UNIV COLLEGE STATION DEPT OF PHYSICS
|
| The photorefractive effect in Barium titanates has been the subject of extensive research in recent years. Because of very large electro-optic coefficients. BaTiO3 has become a unique candidate for a variety of nonlinear optical devices which operate at very low light intensities. Most of these devices use energy transfer between coherent optical beams that interfere inside the crystal while some devices use the extinction of a single beam through beam ... |
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| Phase Conjugation with Saturable Gain and Saturable Absorption, |
22 MAY 1992 |
|
| Authors:
Millvoj Belic; Dejan Timotijevic; Robert W. Boyd; ROCHESTER UNIV NY INST OF OPTICS
|
| We have investigated 2WM and 4WM processes in photorefractive crystals in the nonsaturated regime, i.e. when the coupling between beams and the absorption depend on the light Intensity. Different models of saturable absorption in 2WM via reflection grating are considered, and the corresponding wave equations are solved exactly. The solutions are written in terms of hypergeometric functions or in quadratures. From the solutions it was found that the energy transfer ... |
|
| Instabilities in Coupled Photorefractive Ring Cavities and Self-Pumped Phase Conjugators, |
22 MAY 1992 |
|
| Authors:
Li-Kuo Dai; Yih-Shuh Gou; Claire Gu; Pochi Yeh; NATIONAL CHIAO TUNG UNIV HSINCHU (TAIWAN)
|
| Photorefractive mode coupling between resonators provides a simple model for self-pumped phase conjugators where instabilities may occur due to energy transfer between different oscillation modes inside the crystal. In this paper, we consider the dynamical behaviors of mode coupling between two unidirectional ring resonators. The first resonator is driven by an external laser beam via photorefractive two-wave mixing. The internal oscillating beam is then employed to drive the second ring ... |
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| Soliton Propagation in Media with Non Central Symmetry, |
22 MAY 1992 |
|
| Authors:
Qi Guo; Chang Jun Liao; Shong Hao liu; SOUTH CHINA NORMAL UNIV GUANGZHOU
|
| The second-order susceptibility describes the energy transfer of second-order nonlinear optical effects in media with non-central symmetry. In the waveguides made of this kind of media, however, if the phase-matching condition is not satisfied, the effects are very weak in the propagation distance that the wave interaction length is much longer than the coherent length (the wave interaction length can be very long, when the guides have low loss.). It ... |
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| Interaction of Low-Energy Electronics with Adsorbed Molecules: Mechanisms of Energy Transfer and Dissociation, |
22 MAY 1992 |
|
| Authors:
Leon Sanche; SHERBROOKE UNIV (QUEBEC)
|
| The chemical reactivity of molecules physisorbed or chemisorbed on solid surfaces is a topic of interest in many areas of applied physics and chemistry. A large portion of the activity in this field of research has been focused on the catalytic action of surfaces; however, the recent discoveries on the possibility to enhance, trigger and even control chemical reactions with photon and particle beams incident on surfaces are now starting ... |
|
| State Specific of the Laser Induced Desorption of NO from Si 111, |
22 MAY 1992 |
|
| Authors:
L. J. Richter; S. A. Buntin; D. S. King; R. R. Cavanagh; NATIONAL INST OF STANDARDS AND TECHNOLOGY GAITHERSBURG MD
|
| A wide variety of chemical processes at semiconductor surfaces have been observed to be promoted by radiation. The possible mechanisms for the transfer of the initial photon energy to the reaction coordinate are many, including simple substrate heating, substrate carrier driven reactions, and localized adsorbate photoexcitation. State-resolved studies of laser-induced reaction products have proven extremely illuminating as they often allow the distinction and quantification of various competing excitation mechanisms. We ... |
|
| Persistent Hole Burning Study of Core Antenna of Photosystem, |
22 MAY 1992 |
|
| Authors:
M. Vacha; F. Adamec; M. Ambroz; J. Dian; L. Nedbal; CHARLES UNIV PRAGUE (CZECHOSLOVAKIA) FACULTY OF MATHEMATICS AND PHYSICS
|
| The application of hole burning spectroscopy (HB) in the study of photosynthetic systems offers an independent method for determining excited state lifetimes of particular chromophores. The rate constants of excitation energy transfer (EET) in photosynthetic antennae can be directly determined by time resolved fluorescence spectroscopy. For most bacterial and higher plants antennae is of the order of 10 to the -12 power/s. Efficient EET in pigment-protein complexes causes significant shortening ... |
|
| Hole Burning of the Exciton Coupled Antenna Complex of Rhodobacter Sphaeroides, |
22 MAY 1992 |
|
| Authors:
N. R. Reddy; G. J. Small; IOWA STATE UNIV AMES
|
| Efficient energy transfer in light harvesting (LH) complexes forms an important part of the photosynthetic process that results in the conversion of light energy into chemical free energy. A number of factors are important for understanding the process that directs the optical excitation to the reaction center. Included are the nature of relevant excited states of chlorophylls (e.g. localised or delocalised), bath induced mechanisms for homogeneous broadening of transitions etc. ... |
|
| A New Type Photon-Gated Photochemical Hole Burning by Two-Color-Sensitized Photoreaction, |
22 MAY 1992 |
|
| Authors:
Kazuyuki Horie; Shinjiro Machida; Takashi Yamashita; TOKYO UNIV (JAPAN)
|
| Photochemical Hole Burning (PHB) has attracted considerable interest not only as a tool for high resolution spectroscopy of amorphous solid at low temperature but also as a possible means for frequency-domain high-density optical storage. Many recent investigations have been devoted to a photon-gated mechanism because it allows nondestructive readout in utilizing PHB for a practical optical memory system. The mechanisms of previously reported photon-gated PHB systems are two-step photoionization, photodecomposition, ... |
|
| Persistent Hole Burning Spectroscopy Applications on Phthalocyanine Langmuir-Blodgett Films, |
22 MAY 1992 |
|
| Authors:
F. Adamec; M. Ambroz; E. Brynda; J. Dian; M. Vacha; CHARLES UNIV PRAGUE (CZECHOSLOVAKIA) FACULTY OF MATHEMATICS AND PHYSICS
|
| Phthalocyanine Langmuir Blodgett (LB) films represent ultra thin monomolecular layers with molecules in tight contact. Most of the phthalocyanine molecules in LB films are ordered in domains where they occupy well defined (parallel) positions. There is also a minority of non-ordered molecules in off-domain positions in LB films. This fact is well documented in X-ray diffraction and transmission electron diffraction. Moreover, significant inhomogeneous broadening of absorption spectra of LB film ... |
|
| Electronic Energy Transfer between Donor and Acceptor Adlayers on Single-Crystal Surfaces: Distance and Coverage Dependence, |
22 MAY 1992 |
|
| Authors:
D. R. Haynes; A. Tokmakoff; S. M. George; STANFORD UNIV CA DEPT OF CHEMISTRY
|
| Electronic energy transfer in surface adlayers is a mechanism of fundamental importance to surface photochemical processes. In this study, the electronic energy transfer from a donor p-terphenyl (TP) adlayer to an acceptor 9,10-diphenylanthracene (DPA) adlayer was studied using quantum yield measurements at 30 K and 85 K. These investigations employed an A1203(0001) crystal surface as a two-dimensional support on which donor, spacer and acceptor adlayers could be sequentially adsorbed. The ... |
|
| Nonlinear Directional Coupler Switched by the External Wave, |
22 MAY 1992 |
|
| Authors:
Ewa Weinert-Raczka; WARSAW TECHNICAL UNIV (POLAND)
|
| A typical Nonlinear Directional Coupler (NLDC) permits power dependent energy transfer between two adjacent waveguides. The output of the device can be controlled by the input power solely for high energy signals. For weak fields NLDC works like a linear coupler with the output dependent only on the device design. NLDC working with weak modes and controlled by a strong field at a different frequency guided by the central region ... |
|
| Experimental Comparison of the 'AC Field'and 'Moving Grating' Techniques for BTO and BSO Crystals, |
22 MAY 1992 |
|
| Authors:
E. V. Mokrushina; V. V. Prokof'ev; S. L. Sochava; S. I. Stepanov; AKADEMIYA NAUK SSSR LENINGRAD FIZIKO-TEKHNICHESKII INSTITUT
|
| There are two techniques of nonstationary holographic recording which are widely used for PRCs with long drift lengths of photocarriers. There are recording of a moving interference pattern in an external DC electric field and recording of a fixed pattern in an AC field. Both of them allow the efficiency of the drift mechanism of recording in the external electric field to be increased and the recorded hologram to be ... |
|
| High Translational Energy Induced Reaction in Semiconductors |
05 MAY 92 |
8 pages |
| Authors:
Wilson Ho; CORNELL UNIV ITHACA NY LAB OF ATOMIC AND SOLID STATE PHYSICS
|
| The main objectives of this project are to develop novel instrumentation and to understand bond breaking and formation on semiconductor surfaces. The approaches used in achieving these objectives are to determine the dependence of adsorption on the translational and vibrational energies of incident molecules and to investigate energy exchange at surfaces. The systems which have been investigated in detail are the dissociative adsorption of carbon dioxide and the nondissociative adsorption ... |
|
| Informal Conference on Photochemistry Held in Atlanta, Georgia on 26 April-1 May, 1992 |
01 MAY 92 |
236 pages |
| Authors:
Paul H. Wins; GEORGIA TECH RESEARCH CORP ATLANTA
|
| The XXth Informal Conference on Photochemistry was held at the Colony Square Hotel in Atlanta, Georgia during the period April 26 - May 1, 1992. A total of 74 oral papers and 105 poster papers were presented. Most participants agreed that the scientific level of the conference was very high. One of the goals of this conference was to bring together leading researchers in a variety of basic and applied ... |
|
| Nonstationary Time Series Analysis of Many-Body Dynamics |
MAY 92 |
18 pages |
| Authors:
Craig C. Martens; CALIFORNIA UNIV IRVINE DEPT OF CHEMISTRY
|
| A method for the analysis of computer simulations of ultrafast dynamical processes in many-body systems is presented, based on a joint time- frequency Wigner-Ville distribution calculated from the evolving particle velocities. This quantity has the interpretation of a time and frequency- dependent effective temperature, and the evolution of the distribution allows dynamical information about energy flow between modes and relaxation mechanisms of many-body systems to be obtained. This approach is ... |
|
| Studies of Nonlinear Instabilities of Developing Wake Flows Behind Bluff Bodies and Their Control |
30 APR 92 |
2 pages |
| Authors:
J. T. Liu; BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING
|
|
| JPRS Report, Science & Technology, Japan, New Trends for Advanced Materials |
10 APR 92 |
62 pages |
| Authors:
JOINT PUBLICATIONS RESEARCH SERVICE ARLINGTON VA
|
| There is a need To develop materta1s with Intelligent response capacity In this regard, intelligent materials can play a great role in solving the difficult problems that human society will face. These are "materials that can respond intelligently to environmental conditions and functions". |
|
| Secondary Instability in 3D Magnetic Reconnection |
06 APR 92 |
46 pages |
| Authors:
R. B. Dahlburg; S. K. Antiochos; T. A. Zang; NAVAL RESEARCH LAB WASHINGTON DC
|
| We consider the transition to turbulence in three dimensional reconnection of a magnetic neutral sheet. We find that the transition can occur via a three-step process. First, the sheet undergoes the usual tearing instability. Second, the tearing mode saturates to form a two-dimensional quasi- steady state. Third, this secondary equilibrium is itself unstable when it is perturbed by three-dimensional disturbances. Most of this paper is devoted to the analysis and ... |
|
| Theory of Square Meander-Type Couplers, |
APR 1992 |
|
| Authors:
H.-P. Nolting; HEINRICH-HERTZ-INST FUER NACHRICHTENTECHNIK BERLIN G M B H (GERMANY F R)
|
| Experimental results on the square meander or grating-assisted co-directional coupler have been published recently. The device was employed as a passive wavelength sensitive multiplexer/demultiplexer and as part of a tunable laser. Theoretical analyses were based on a coupled mode method, but no method to calculate the coupling efficiency from a first principles approach, including the case of strong coupling, has been published so far to the best of our knowledge. ... |
|
| Statistical Analysis of the Rate of Strain Tensor in Compressible Homogeneous Turbulence |
APR 92 |
40 pages |
| Authors:
G. Erlebacher; S. Sarkar; INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
|
| Recent analysis of direct numerical simulations of compressible homogeneous shear flow turbulence has unraveled some of the energy transfer mechanisms responsible for the decrease of kinetic energy production when the flow becomes more compressible. In this complementary study, we focus our attention on the rate of strain tensor. A Helmholtz decomposition of the velocity field leads us to consider a solenoidal and an irrotational rate of strain tensor. Their eigenvalue ... |
|
| An Accurate and Efficient Method to Calculate the Rate of Single Event Upsets from the LET Spectrum and SEU Cross Section Test Results |
20 MAR 92 |
42 pages |
| Authors:
D. L. Chenette; T. L. Schumaker; A. E. Williamson; LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CA PALO ALTO RESEARCH LAB
|
| A specific implementation is presented for calculating the rate of single event upsets in microelectronic devices. The implementation is based on the method of Pickel and Blandford (1980), who combined device test results, the flux distribution of particles in the space environment, and a model for the geometry of the device. The device test data are summarized as an upset cross section expressed as a function of the linear energy ... |
|
| Transparent Gel and Xerogel of Thorium Phosphate: Optical Spectroscopy With: Nd3+,Eu3+,Cr3+ and Rhodamine 6G, |
MAR 1992 |
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| Authors:
M. Genet; V. Brandel; M. P. Lahalle; E. Simoni; INSTITUT DE PHYSIQUE NUCLEAIRE ORSAY (FRANCE)
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| Chemical conditions for thorium phosphate gel preparation have been determined. The transparency is of good optical quality and the gel is very stable for a long time. Under drying condition, this gel can give rise to the xerogel which is still transparent. We can also prepare this xerogel by simple evaporation at room temperature of a very concentrated solution of thorium phosphate. From this viscous medium, the xerogel can be ... |
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| Solvation Effects on the Electronic Structure of 4-N,N- Dimethylaminobenzonitrile: Mixing of the Local Pi(pi) and Charge Transfer States |
04 FEB 92 |
34 pages |
| Authors:
E. R. Bernstein; Q.-y. Shang; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
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| The effect of polar solvents acetonitrile and water on the electronic excited states of 4-N,N-dimethylaminobenzonitrile (DMABN), is studied through the optical spectroscopy of small clusters of DMABN/solvent. The clusters are created in a supersonic jet expansion. The results of mass resolved excitation spectroscopy (MRES), fluorescence excitation (FE), dispersed emission (DE), and photo-depletion studies demonstrate that the solvent molecule can bind to DMABN at two distinct sites for the 1:1 cluster. ... |
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