Direct photodissociation of molecules at structured metallic surfaces is considered, where the concepts of optimal and critical distances are introduced into the description of this phenomenon. Numerical results for the distortion of the line shape and the enhancement ratio are obtained for a shallow sinusoidal grating.
Topics: DTIC Archive, Leung,P T, STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY, *PHOTODISSOCIATION,...
This study continues the experimental investigation of the thermal and chemical erosion characteristics of steel alloys which were begun under Contract DAAG46-72-C-0078. The high pressure (approx. 3 kbars) and high temperature (approx. 3000 K) environment to which the steel specimens are subjected is produced by a ballistic compressor and by a solid propellant combustor. Equilibrium thermochemical calculations of the possible reactions indicate that the most probable reaction products are...
Topics: DTIC Archive, Alkidas,A C, PRINCETON UNIV N J DEPT OF AEROSPACE AND MECHANICAL SCIENCES, *GUN...
We have performed experimental measurements of adsorbed atoms and molecules on metal and semiconductor surfaces over a wide range of temperatures (20K - 100K) to identify the nature of bonding, the structure, reaction intermediates and reaction products. This has included simple hydrocarbon and organic molecules on Ni, Pd, Pt and Ag single-crystal surfaces. The techniques of UV photoemission, low energy electron diffraction and high resolution electron energy loss spectroscopy were used and...
Topics: DTIC Archive, Demuth, J E, IBM THOMAS J WATSON RESEARCH CENTER YORKTOWN HEIGHTS NY, *MOLECULES,...
Measurements with an oscillating hydrogen maser of wall collision frequency shift of atomic hydrogen on surfaces of frozen CF4 at temperatures between 60 K and 30 K indicate the same wall interaction energy as for FEP-Teflon surfaces, but with 3 to 4 times less wallshift. This indicates that the surfaces of Teflon have 3 to 4 times the area of those of CF4. A substantial improvement in wall coating performance is shown to be possible with the coatings. Originator furnished keywords include:...
Topics: DTIC Archive, Vessot,R F C, SMITHSONIAN ASTROPHYSICAL OBSERVATORY CAMBRIDGE MA, *HYDROGEN,...
The adsorption of pyridine onto both polycrystalline and single crystal gold electrode surfaces has been investigated using three electrochemical techniques: cyclic voltammetry, differential capacity and chronocoulometry. The surface concentration of pyridine, the Gibbs energy of adsorption, the electrosorption valency and the orientation of the pyridine molecules on the gold electrode surfaces, have been measured. All of these parameters were found to be sensitive to the structure of the gold...
Topics: DTIC Archive, Stolberg, L, GUELPH UNIV (ONTARIO) DEPT OF CHEMISTRY, *SURFACE REACTIONS, *PYRIDINES,...
We report surface vibrations in c(2x2) oxygen adlayers on Ni and Co thin films on a Cu (001) substrate measured at gamma by high resolution EELS. For the Ni thin film surface, one phonon peak is measured for varying film thickness from 1.3 ML (monolayer) to 6 ML with a constant energy of 221cm -1. For the CO thin film surface, three loss peaks are found, whose relative intensities change as the film thicknesses are varied. One loss peak ca. 520 cm -1 is tentatively assigned to the Fuchs-Kliewer...
Topics: DTIC Archive, Kim, J S, INDIANA UNIV AT BLOOMINGTON DEPT OF PHYSICS, *SPECTROSCOPY, EPITAXIAL...
The coherence length of the new high-temperature superconductors reaches a small value which is comparable to the dimensions of the unit cell of the compound. This means that a pair consists of two holes occupying the same site or two adjacent sites. Such a situation is described by a model of the local-pairs (bipolarons). The origin of local-pairs may come not only from strong enough electron or hole-phonon interaction but also from other interactions. Independent of the specific nature of...
Topics: NASA Technical Reports Server (NTRS), FERROELECTRICITY, HIGH TEMPERATURE SUPERCONDUCTORS, MOLECULAR...
The results of investigations on the solid state reactions which occur at the various interfaces in thin composite structures on the elemental and compound semiconductors, silicon and gallium arsenide, are reported. Free energies derived from bulk thermodynamic data predict the direction of oxidation-reduction reactions at interfaces. The identification of the resulting solid state phases used high energy resolution Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS)...
Topics: DTIC Archive, Scheibner,Edwin J, GEORGIA INST OF TECH ATLANTA APPLIED SCIENCES LAB, *GALLIUM...
An investigation was conducted to examine the adhesion and surface chemistry of single-crystal aluminum in contact with single-crystal sapphire (alumina). Pull-off force (adhesion) measurements were conducted under loads of 0. I to I mN in a vacuum of 10(exp -1) to 10(exp -9) Pa (approx. 10(exp -10) to 10(exp -11) torr) at room temperature. An Auger electron spectroscopy analyzer incorporated directly into an adhesion-measuring vacuum system was primarily used to define the chemical nature of...
Topics: NASA Technical Reports Server (NTRS), ADHESION, SURFACE PROPERTIES, SURFACE REACTIONS, SINGLE...
Protoplanetary disks contain abundant quantities of water molecules in both gas and solid phases. The distribution of these two phases in an evolving protoplanetary disk will have important consequences regarding water sequestration in planetary embryos. The boundary between gaseous and solid water is the "ice line" or "snow line" A simplified model that captures the complicated two-branched structure of the ice line is developed and compared with recent investigations. The...
Topics: NASA Technical Reports Server (NTRS), PROTOPLANETARY DISKS, SOLID PHASES, ICE, VAPOR PHASES,...
Subsonic jets are relatively simple. The peak noise source location gradually moves upstream toward the nozzle as frequency increases. 2) Supersonic jets are more complicated. The peak noise source location moves downstream as frequency increases through a BBSN hump. 3) In both subsonic and supersonic jets the peak noise source location corresponding to a given frequency of noise moves downstream as jet Mach number increases. 4) The noise generated at a given frequency in a BBSN hump is...
Topics: NASA Technical Reports Server (NTRS), SUPERSONIC JET FLOW, JET AIRCRAFT NOISE, NOISE GENERATORS,...
An experimental and theoretical investigation was carried out to evaluate the degradation of the solar cells and other sensitive surfaces of a spacecraft, resulting from the molecular outgassing of an expended solid propellant apogee motor. The motor, following its burnout, is retained by the spacecraft and is a source of gases and particulates which will be released mainly by the unburned propellant-to-casing insulation. The deployment of the solar array within a few minutes after the motor...
Topics: NASA Technical Reports Server (NTRS), APOGEE BOOST MOTORS, DEGRADATION, OUTGASSING, SPACECRAFT...
The effect of an ammonia environment on the spectral reflectance of certain optical surfaces in the vacuum ultraviolet region was studied. In particular, the optical surfaces in the space shuttle were considered. Scans made of sample beams showed no change in the relative intensities before or after exposure to ammonia. Ammonia showed no effect on the Al/MgF2 mirror reflectance in the vacuum ultraviolet.
Topics: NASA Technical Reports Server (NTRS), AMMONIA, OPTICAL PROPERTIES, REENTRY, SPACE SHUTTLES, SURFACE...
Superfluidity and nucleation concepts demonstrated by superfluid helium in finite geometries which can be tested in spaceborne experiments are discussed. Three specific problems are addressed: the liquid vapor interface, films and droplets, and ion induced clusterings.
Topics: NASA Technical Reports Server (NTRS), LOW TEMPERATURE, SPACEBORNE EXPERIMENTS, SURFACE REACTIONS,...
An electronic optical laser interferometer capable of resolving depth differences of as low as 30 A and planar displacements of 6000 A was constructed to examine surface profiles of bearing surfaces without physical contact. Topological chemical reactivity was determined by applying a drop of dilute alcoholic hydrochloric acid and measuring the profile of the solid surface before and after application of this probe. Scuffed bearing surfaces reacted much faster than virgin ones but that bearing...
Topics: NASA Technical Reports Server (NTRS), BEARINGS, LASER INTERFEROMETRY, PHASE LOCKED SYSTEMS, SURFACE...
Burner rig tests were conducted under the following conditions: 900 C, hourly thermal cycling, 0.5 ppm sodium as MaCl in the gas stream, velocity 0.3 Mach. The alloys are Udiment 700, Rene 80, uncoated and with RT21, Codep, or NiCoCrAlY coatings. These tests were completed for specimens in the as-processed condition and after aging at 1100 C in oxidizing or inert evnivronments for time up to 600 hours. Coil inductance changes used for periodic nondestructive inspection of specimens were useful...
Topics: NASA Technical Reports Server (NTRS), ALLOYS, HOT CORROSION, LIFE (DURABILITY), METAL COATINGS,...
A critical issue with oxidation protected carbon/carbon composites used for spacecraft thermal protection is the formation of coating pinholes. In laboratory experiments, artificial pinholes were drilled through SiC-coatings on a carbon/carbon material and the material was oxidized at 600, 1000, and 1400 C at reduced pressures of air. The attack of the carbon/carbon was quantified by both weight loss and a novel cross-sectioning technique. A two-zone, one dimensional diffusion control model was...
Topics: NASA Technical Reports Server (NTRS), OXIDATION, CARBON-CARBON COMPOSITES, COATING, PINHOLES,...
Sodium in the lunar exosphere is released from the lunar regolith by several mechanisms. These mechanisms include photon stimulated desorption (PSD), impact vaporization, electron stimulated desorption, and ion sputtering. Usually, PSD dominates; however, transient events can temporarily enhance other release mechanisms so that they are dominant. Examples of transient events include meteor showers and coronal mass ejections. The interaction between sodium and the regolith is important in...
Topics: NASA Technical Reports Server (NTRS), SODIUM, EXOSPHERE, LUNAR ROCKS, DENSITY DISTRIBUTION,...
Experimental technique used in study of damage mechanism to semiconductor pigments exposed to ultraviolet radiation can be adapted for investigations of surface chemistry and may be used analytically to determine contamination.
Topics: NASA Technical Reports Server (NTRS), CARBON DIOXIDE, CONTAMINATION, DEGRADATION, GAS PRESSURE,...
An iron surface was exposed to the extreme-pressure type lubricant benzyl chloride, dichlorophenyl phosphine, dichlorophenyl phosphine sulfide, ophenyl phosphine oxide. Iron, in the sputter-cleaned state, was exposed to these materials statically and during dynamic friction experiments. With benzyl chloride only chlorine adsorbed to the surface, and with dichlorophenyl phosphine no adsorption occurred, while the addition of sulfur to that same molecular structure resulted in the promotion of...
Topics: NASA Technical Reports Server (NTRS), HIGH PRESSURE, IRON, LUBRICANT TESTS, SURFACE REACTIONS,...
Developments in the following areas are reported: surface area and pore size distribution in electrolyte matrices, electron microscopy of electrolyte matrices, surface tension of KOH solutions, water transport in fuel cells, and effectiveness factors for fuel cell components.
Topics: NASA Technical Reports Server (NTRS), ELECTROCHEMISTRY, ELECTROLYTES, FUEL CELLS, MASS TRANSFER,...
The thermal and structural performance of a large panel of LI-1542 reusable surface insulation tiles was determined by a series of cyclic heating tests using radiant lamps and aerothemal tests in the Langley 8-foot high-temperature structures tunnel. Aerothermal tests were conducted at a free-stream Mach number of 6.6, a total temperature of 1830 K, Reynolds numbers of 2.0 and 4,900,000 per meter, and dynamic pressures of 29 and 65 kPa. The results suggest that pressure gradients in gaps and...
Topics: NASA Technical Reports Server (NTRS), HYPERSONIC HEAT TRANSFER, HYPERSONIC TEST APPARATUS,...
In order to study the basic mechanisms of erosion, hardened steel balls were shot into annealed 6061 Al alloy targets at velocity of up to 150 m/sec. The projectiles were collected and examined by a scanning electron microscope combined with energy-dispersive X-ray analyzer and it was found that target material in substantial amounts is adhesively transferred to the projectile. The transferred material forms on the projectile surface a layer the thickness of which increases with increases in...
Topics: NASA Technical Reports Server (NTRS), ADHESION, ALUMINUM ALLOYS, EROSION, METAL SURFACES, SURFACE...
Fabrication and characterization of high-efficiency metal insulator, n-p (MINP) cells is described. Particular attention was paid to development of measurement methods for surface recombination and density of surface states. A modified Rosier test structure was used successfully for density of surface states. Silicon oxide and silicon nitride passivants were studied. Heat treatment after plasma enhanced chemical vapor deposition (CVD) of silicon nitride was shown to be beneficial. A more...
Topics: NASA Technical Reports Server (NTRS), ENERGY CONVERSION EFFICIENCY, FABRICATION, MIS...
The NASA Evaluation of Oxygen Interactions with Materials-3 (EOIM-3) experiment served as a test bed for a variety of materials that are candidates for Ballistic Missile Defense Organization (BMDO) space assets. The materials evaluated on this flight experiment were provided by BMDO contractors and technology laboratories. A parallel ground exposure evaluation was conducted using the FAST atomic-oxygen simulation facility at Physical Sciences, Inc. The EOIM-3 materials were exposed to an atomic...
Topics: NASA Technical Reports Server (NTRS), BALLISTIC MISSILES, FLIGHT TESTS, FLUENCE, GROUND TESTS,...
Knowledge of the oxidation, ignition, and combustion of bulk metals is important for fire safety in the production, management, and utilization of liquid and gaseous oxygen for ground based and space applications. This report summarizes research under NASA support to investigate the ignition and combustion characteristics of bulk metals under varying gravity conditions. Metal ignition and combustion have not been studied previously under these conditions and the results are important not only...
Topics: NASA Technical Reports Server (NTRS), COMBUSTION PHYSICS, FIRE PREVENTION, GRAVITATIONAL EFFECTS,...
This volume is a compilation of papers presented at the Third Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science. In addition, papers on preliminary data analysis of EURECA, EOIM-3, and other spacecraft are...
Topics: NASA Technical Reports Server (NTRS), AEROSPACE ENVIRONMENTS, CONFERENCES, ENVIRONMENT SIMULATION,...
Microgravity processes must rely on mechanisms other than bouyancy to move bubbles or droplets from one region to another in a continuous liquid phase. One suggested method is thermocapillary migration in which a temperature gradient is applied to the continuous phase. When a fluid particle contacts this gradient, one pole of the particle becomes warmer than the opposing pole. The interfacial tension between the drop or bubble phase and the continuous phase usually decreases with temperature....
Topics: NASA Technical Reports Server (NTRS), CAPILLARY FLOW, BUBBLES, MICROGRAVITY, DROPS (LIQUIDS),...
The University of Alabama experiment which flew on the STS-8 mission had several objectives which were mostly of a speculative nature since so little was known of the processes of interest. The experiment provided original data on: (1) oxidation of metal surfaces; (2) reaction rates of atomic oxygen with carbon and other surfaces and the dependence of these rates on temperature; and (3) the angular distribution of 5 eV atoms scattered off a solid surface. A review of the results is provided.
Topics: NASA Technical Reports Server (NTRS), EARTH ORBITAL ENVIRONMENTS, EXPOSURE, OXYGEN ATOMS,...
Thin films of the following polymers were exposed at ambient temperature to ground-state oxygen atoms (O(3P)), generated by a radio-frequency glow discharge in O2: cis- and trans-1,4-polybutadienes (CB and TB), amorphous 1,2-polybutadiene (VB), polybutadienes with different 1,4/1,2 contents, trans polypentenamer (TP), cis and trans polyoctenamers (CO and TO), and ethylene-propylene rubber (EPM). Transmission infrared spectra of CB and TB films revealed extensive surface recession, or etching,...
Topics: NASA Technical Reports Server (NTRS), ELASTOMERS, ETCHING, GAS-SOLID INTERACTIONS, OXYGEN ATOMS,...
The adhesion, friction, and wear behavior of silicon nitride films deposited by low- and high-frequency plasmas (30 kHz and 13.56 MHz) at various temperatures to 700 C in vacuum were examined. The results of the investigation indicated that the Si/N ratios were much greater for the films deposited at 13.56 MHz than for those deposited at 30 kHz. Amorphous silicon was present in both low- and high-frequency plasma-deposited silicon nitride films. However, more amorphous silicon occurred in the...
Topics: NASA Technical Reports Server (NTRS), ADHESION, DEPOSITION, FRICTION, SILICON NITRIDES, TEMPERATURE...
The extent of surface destabilization of ZrO2 - 8 wt percent Y2O3 ceramic disks was determined after exposure to molten salt mixtures of sodium sulfate containing up to 15 mole percent sodium metavanadate (NaVO3) at 1173 K. The ceramic surface was observed to transform from the cubic/tetragonal to monoclinic phase, concurrent with chemical changes in the molten salt layer in contact with the ceramic. Significant attack rates were observed in both pure sulfate and metavanadate sulfate melts. The...
Topics: NASA Technical Reports Server (NTRS), CERAMICS, CHEMICAL ATTACK, MOLTEN SALTS, PHASE...
EnviroNET is an operational system available to the Strategic Defense Initiative (SDI) experimenters who have access to a terminal or dial-up port. It is a tail node on Space Physics Analysis Network (SPAN) accessible directly or through the national networks via NPSS. Some of the benefits to using EnviroNET include: validated NASA environmental information and interactive space models; facilitating the payload integration process; easy access to expert assistance; and potential for time and...
Topics: NASA Technical Reports Server (NTRS), COMPUTER NETWORKS, COMPUTER PROGRAMS, EARTH ORBITAL...
The Solar Maximum Repair Mission returned with the replaced hardware that had been in low Earth orbit for over four years. The materials of this returned hardware gave the aerospace community an opportunity to study the realtime effects of atomic oxygen, solar radiation, impact particles, charged particle radiation, and molecular contamination. The results of these studies are summarized.
Topics: NASA Technical Reports Server (NTRS), MAINTENANCE, ORBITAL SERVICING, RADIATION EFFECTS, SOLAR...
The uniaxial fatigue behavior of a single crystal superalloy, PWA 1480, is described. Both monotonic tensile and constant amplitude fatigue tests were conducted at room temperature, in an effort to assess the applicability of polycrystalline-based fatigue life prediction methods to a single crystal superalloy. The observed constant amplitude behavior correlated best using a stress-based life criterion. Nearly all specimens failed at surface or slightly subsurface microporosity; this is thought...
Topics: NASA Technical Reports Server (NTRS), DAMAGE ASSESSMENT, FATIGUE LIFE, HEAT RESISTANT ALLOYS, METAL...
A device for the production of low energy (3 to 10 eV) neutral atomic beams for surface modification studies is described that reproduces the flux of atomic oxygen in low Earth orbit. The beam is produced by the acceleration of plasma ions onto a negatively biased plate of high-Z metal; the ions are neutralized and reflected by the surface, retaining some fraction of their incident kinetic energy, forming a beam of atoms. The plasma is generated by a coaxial RF exciter which produces a...
Topics: NASA Technical Reports Server (NTRS), ATOMIC BEAMS, EARTH ORBITAL ENVIRONMENTS, ENVIRONMENT...
Insufficient electrode life and uncertainties in that life are major problems hampering the development in many plasma application areas which make use of plasma torches, arc heaters, and arc jet thrusters. In spite of a considerable amount of work published dealing with arc-cathode phenomena, our present understanding is still incomplete because different physical phenomena dominate for different combinations of experimental parameters. The objective of our present research project is to gain...
Topics: NASA Technical Reports Server (NTRS), ARC HEATING, CATHODES, ELECTRODE MATERIALS, SURFACE...
Abstracts
Topics: DTIC Archive, Morawitz,Hans, NATIONAL SCIENCE FOUNDATION WASHINGTON DC DIV OF MATERIAL SCIENCES,...
A generalized method is presented for solving the problem of stagnation point heat transfer and material response for blunt bodies experiencing melting and vaporizing or subliming ablation. The analysis is applicable to wind-tunnel and flight conditions (with body forces taken into account); internal radiation can be considered or the material can be assumed opaque; the analysis can be used for different planets. During entry flights, a body will start in the free-molecule regime, pass through...
Topics: DTIC Archive, Matting, Fred W., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
This AASERT grant provided augmentation funds that helped support US citizen graduate student research in the area of surface science. These efforts focussed on gas-surface reactions, collisional energy transfer, and surface metallurgy, with the latter area encompassing such important topics as metallic surface structure, force constants and bonding at interfaces, structural change due to adsorption/absorption, step dynamics, and the kinetics of surface oxidation and corrosion. This award...
Topics: DTIC Archive, Sibener, Steven J., CHICAGO UNIV IL, *AUGMENTATION, *SURFACE REACTIONS, SCANNING,...
2,4,6-Trinitrotoluene (TNT) has contaminated the wastewater emanating from plants engaged in not only the manufacture but also the loading, assembling and packing of TNT. It has been found that certain surfactants containing amino groups reacted rapidly with TNT in aqueous solution. The reaction product was a dark brown material which was insoluble in water. When the initial concentration of TNT was in the range of 120-140 ppm, after reacting with surfactant the TNT concentration in the...
Topics: DTIC Archive, Okamoto,Y, POLYTECHNIC INST OF NEW YORK BROOKLYN DEPT OF CHEMISTRY, *WATER POLLUTION...
A significant body of work is beginning to appear on the chemistry of amines and organic cyanides on single crystal transition metal surfaces in UHV. In particular, the thermal chemistry of cyanogen (C2N2) adsorbed on single-crystal platinum surfaces has been examined by a number of authors. The results from studies on Pt(100), Pt(110), Pt(111), and a stepped Pt surface with Pt(111) terraces show a qualitative insensitivity of C2N2 chemistry to the structure of the underlying platinum surfaces....
Topics: DTIC Archive, Lloyd,Kathryn G, CALIFORNIA UNIV IRVINE DEPT OF CHEMISTRY, *SPECTROSCOPY, *HYDROGEN,...
It was found in this investigation that an alloying reaction occurred wherever and whenever clean metallic surfaces of aluminum and uranium were brought into contact within the temperature range of 250OC to 450oC. Anodization of the aluminum surface prevented the alloying reaction. The effects of temperature. aluminum purity, and pressure between the metal surfaces on the alloying reaction were studied qualitatively. The alloying reaction produced UAl3, which appeared to be formed by the...
Topics: DTIC Archive, Bareis, D. W., ATOMIC ENERGY COMMISSION WASHINGTON DC, *ALUMINUM ALLOYS, *SURFACE...
Chemisorption of nitrogen and hydrogen on densely packed planes of tungsten, molybdenum, iridium, and rhenium has been studied by probe-hole field emission microscopy. Adsorption on perfect planes, as well as on planes containing structural defects, has been investigated. The results can be interpreted by the promotion of chemisorption at structural defects on smooth surfaces. A model, which can account for our results as well as observations on macroscopic surfaces, is presented. (Author)
Topics: DTIC Archive, Liu,Ruichen, ILLINOIS UNIV AT URBANA-CHAMPAIGN COORDINATED SCIENCE LAB, *MOLYBDENUM,...
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Jul 21, 2010
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NON
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A survey of the free world's aeronautical facilities was undertaken and an evaluation made on where the relative strengths and weaknesses exist. Special emphasis is given to NASA's own capabilities and needs. The types of facilities surveyed are: Wind Tunnels; Airbreathing Propulsion Facilities; and Flight Simulators
Topics: AEROSOLS, MATHEMATICAL MODELS, POLLUTION TRANSPORT, RADIATIVE TRANSFER, REACTION KINETICS, SOLAR...
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Hammond, Ernest C., Jr
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Since the United States of America is moving into an age of reusable space vehicles, both electronic and photographic materials will continue to be an integral part of the recording techniques available. Film as a scientifically viable recording technique in astronomy is well documented. There is a real need to expose various types of films to the Shuttle environment. Thus, the main objective was to look at the subtle densitometric changes of canisters of IIaO film that was placed aboard the...
Topics: CHROMIUM, ELECTRON SPECTROSCOPY, FIBER-MATRIX INTERFACES, HIGH TEMPERATURE, SCANNING ELECTRON...
The following research areas were undertaken in this report: Phonon Transport in the Presence of Quasidiffusion; Generation of Coherent THz Phonons through Piezoelectric Surface Excitation; Phonon Lifetimes in the Picosecond Time Domain; and Phonon Transport Across Solid-Solid Interfaces.
Topics: DTIC Archive, Bron,W E, INDIANA UNIV AT BLOOMINGTON, *Semiconductors, *Transport properties,...
This investigation is directed toward obtaining a fundamental understanding of lubricant foaming and aeration. On the practical side, foam tests showed that the surface activity of additives varies from one production batch to another, requiring continuing testing before acceptance. On the fundamental side, three independent techniques were developed to measure dynamic (nonequilibrium) surface tensions of oils containing additives, to obtain simpler correlative physical properties of oil...
Topics: DTIC Archive, Ross,Sydney, RENSSELAER POLYTECHNIC INST TROY NY, *LUBRICANTS, *AERATION, PRODUCTION,...
All the investigations which were performed employed in one way or another a computer simulation technique based on atomistic level considerations. In general, three types of simulation methods were used for modeling systems with discrete particles that interact via well defined potential functions: molecular dynamics (a general method for solving the classical equations of motion of a model system); Monte Carlo (the use of Markov chain ensemble averaging technique to model equilibrium...
Topics: NASA Technical Reports Server (NTRS), CHEMICAL REACTIONS, COMPUTERIZED SIMULATION, CRACK...
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Joiner, J.; Dee, D. P
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One of the outstanding problems in data assimilation has been and continues to be how best to utilize satellite data while balancing the tradeoff between accuracy and computational cost. A number of weather prediction centers have recently achieved remarkable success in improving their forecast skill by changing the method by which satellite data are assimilated into the forecast model from the traditional approach of assimilating retrievals to the direct assimilation of radiances in a...
Topics: COPPER ALLOYS, METAL SURFACES, NICKEL ALLOYS, MONTE CARLO METHOD, SOLID SURFACES, SURFACE...
