The knock-limiting performance of fuel blends containing aromatics Part I : toluene, ethyl-benzene, and p-xylene
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ENGINES - PERFORMANCE EFFECT OF ANTIKNOCK FUELS↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Effect of Blade Loading on the Climb and High-speed Performance of a Three-blade Hamilton Standard No. 6507A-2 Propeller on a Republic P-47D Airplane
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Gardner, John J↗
Flight measurements of the effect on elevator stick forces of stabilizer incidence and elevator rib spacing on the P-63A-1BE series airplane
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Mungall, Robert G↗
Modifications of airborne oceanographic lidar for the long range P-3 missions
This has been an extraordinary series of Airborne Oceanographic Lidar (AOL) missions. The AOL was flown over the North Pole on three low altitude sea ice mapping flights. These flights were followed by six Joint Global Ocean Flux Study (JGOFS) flights based from Hawaii and Christmas Island to measure chlorophyll along the equator. On return to the west coast, there were several terrain mapping flights in Nevada and Arizona. This was followed by mapping of the Greenland ice cap from the airport at Sondresstrom Greenland. This research proposal was developed to support the AOL instrumentation research that prepares the AOL for each science mission. Saint Vincent College physics professor, Dr. Richard Berry, is engaged in LIDAR instrumentation research to improve the AOL. Dr. Berry's participation in the AOL mission was to implement the instrumentation modifications that optimized data acquisition.
Berry, Richard E.↗
The Twenty-Fifth Lunar and Planetary Science Conference. Part 3: P-Z
Various papers on lunar and planetary science are presented, covering such topics as: impact craters, tektites, lunar geology, lava flow, geodynamics, chondrites, planetary geology, planetary surfaces, volcanology, tectonics, topography, regolith, metamorphic rock, geomorphology, lunar soil, geochemistry, petrology, cometary collisions, geochronology, weathering, and meteoritic composition.
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Non-contacting gas lubricated face seals for high p x v-values
The authors discuss recently developed mathematical fundamentals concerning the calculation of noncontacting gas lubricated face seals. They carried out extensive experiments using three different designs at pressures up to 10 MPa and sliding velocities up to 110 m/s. A comparison between the experimental results and the calculations indicates that a stable operation without wear can be ensured in all cases, provided that the materials and geometrical parameters of the seal have been properly chosen.
Glienicke, J.↗
Comment on 'Formation of Venusian canali': Considerations of lava types and their thermal behaviors' by T. K. P. Gregg and R. Greeley
Gregg and Greeley (1993) evaluated the mechanisms by which various magma types might have formed the long sinuous channels apparent on the surface of Venus. Among the magma types they evaluated were carbonatites, which are carbonate-rich ionic liquids. Gregg and Greeley (1993) applied thermophysical data for terrestrial carbonatite magmas to evaluate channel formation by carbonatites on Venus. Their analysis is flawed because they used incorrect values for the solidification temperatures of carbonatite magmas.
Treiman, Allan H.↗
Thermally stable, low resistance contact systems for use with shallow junction p(+) nn(+) and n(+)pp(+) InP solar cells
Two contact systems for use on shallow junction InP solar cells are described. The feature shared by these two contact systems is the absence of the metallurgical intermixing that normally takes place between the semiconductor and the contact metallization during the sintering process. The n(+)pp(+) cell contact system, consisting of a combination of Au and Ge, not only exhibits very low resistance in the as-fabricated state, but also yields post-sinter resistivity values of 1(exp -7) ohms-sq cm, with effectively no metal-InP interdiffusion. The n(+)pp(+)cell contact system, consisting of a combination of Ag and Zn, permits low resistance ohmic contact to be made directly to a shallow junction p/n InP device without harming the device itself during the contacting process.
Weizer, V. G.↗
PtSi/Si MWIR Detectors Made With p+ Doping Spikes
Ptsi/Si Schottky-barrier devices detecting medium-wavelength infrared (MWIR) photons demonstrated. Cutoff wavelengths extended to 7 micrometer and dark currents low enough that when cooled to temperature of liquid nitrogen devices suitable for night imaging of scenes at temperatures less than 0 degrees C.
Lin, True-Lon↗
The First Joint Report of the General Thomas P. Stafford Task Force and the Academician Vladimir F. Utkin Advisory Expert Council on the Shuttle-Mir Rendezvous and Docking Missions
In October 1992, the National Aeronautics and Space Administration (NASA) and the Russian Space Agency (RSA) formally agreed to conduct a fundamentally new program of human cooperation in space. The 'Shuttle-Mir Program' encompassed combined astronaut-cosmonaut activities on the Shuttle, Soyuz Test Module(TM), and Mir station spacecraft. At that time, NASA and RSA limited the project to: the STS-60 mission carrying the first Russian cosmonaut to fly on the U.S. Space Shuttle; the launch of the first U.S. astronaut on the Soyuz vehicle for a multi-month mission as a member of a Mir crew; and the change-out of the U.S.-Russian Mir crews with a Russian crew during a Shuttle rendezvous and docking mission with the Mir Station. The objectives of the Phase 1 Program are to provide the basis for the resolution of engineering and technical problems related to the implementation of the ISS and future U.S.-Russian cooperation in space. This, combined with test data generated during the course of the Shuttle flights to the Mir station and extended joint activities between U.S. astronauts and Russian cosmonauts aboard Mir, is expected to reduce the technical risks associated with the construction and operation of the ISS. Phase 1 will further enhance the ISS by combining space operations and joint space technology demonstrations. Phase 1 also provides early opportunities for extended U.S. scientific and research activities, prior to utilization of the ISS.
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Site-Competition Epitaxy for N-Type and P-Type Dopant Control in CVD Sic Epilayers
The use of site-competition epitaxy, which is based on intentional variation of the Si/C ratio during epitaxy, has now been reproduced in numerous national and international laboratories. However, previous reports have only considered dopant incorporation control for epitaxy on the Si-face 6H-SiC(OOO1) substrates. Presented in this paper is the extension of this technique for control of phosphorous incorporation and also a comparison of controlled doping on C-face 6H-SiC(OOO1) versus Si-face 6H-SiC(OOO1) substrates for aluminum, boron, nitrogen, and phosphorous.
Larkin, D. J.↗
Development and Characterization of SiC)/ MoSi2-Si3N4(p) Hybrid Composites
Intermetallic compound MoSi2 has long been known as a high temperature material that has excellent oxidation resistance and electrical/thermal conductivity. Also its low cost, high melting point (2023 C), relatively low density (6.2 g/cu cm versus 9 g/cu cm for current engine materials), and ease of machining, make it an attractive structural material. However, the use of MoSi2 has been hindered due to its poor toughness at low temperatures, poor creep resistance at high temperatures, and accelerated oxidation (also known as 'pest' oxidation) at temperatures between approximately 450 and 550 C. Continuous fiber reinforcing is very effective means of improving both toughness and strength. Unfortunately, MoSi2 has a relatively high coefficient of thermal expansion (CTE) compared to potential reinforcing fibers such as SiC. The large CTE mismatch between the fiber and the matrix resulted in severe matrix cracking during thermal cycling. Addition of about 30 to 50 vol % of Si3N4 particulate to MoSi2 improved resistance to low temperature accelerated oxidation by forming a Si2ON2 protective scale and thereby eliminating catastrophic 'pest failure'. The Si3N4 addition also improved the high temperature creep strength by nearly five orders of magnitude, doubled the room temperature toughness and significantly lowered the CTE of the MoSi2 and eliminated matrix cracking in SCS-6 reinforced composites even after thermal cycling. The SCS-6 fiber reinforcement improved the room temperature fracture toughness by seven times and impact resistance by five times. The composite exhibited excellent strength and toughness improvement up to 1400 C. More recently, tape casting was adopted as the preferred processing of MoSi2-base composites for improved fiber spacing, ability to use small diameter fibers, and for lower cost. Good strength and toughness values were also obtained with fine diameter Hi-Nicalon tow fibers. This hybrid composite remains competitive with ceramic matrix composites as a replacement for Ni-base superalloys in aircraft engine applications.
Hebsur, Mohan G.↗
P-V-T Properties of Polyimides and Model Imide Compounds
Aromatic polyimides are used as matrix resins in advanced composites, as high strength films, and as high-temperature adhesives, owing in part to their unusual thermal and chemical stability. The polyimides' desirable qualities of very high softening temperatures and negligibly small solubilities in and low permeabilities by most solvents have limited the kinds of fundamental studies that can be performed on these systems. Consequently, relationships between the molecular structure of polyimides and their bulk properties are not as well understood as might be expected given their widespread applications. In particular, the intermolecular forces in polyimides that play a critical role determining their densities, solubilities, viscosities, moduli, glass transitions, etc. are less well characterized for polyimides than for other widely used polymeric materials. The purpose of the present study is to obtain experimental data for establishing parameters that characterize the intermolecular forces in polyimides. We report here our studies on tractable low molecular-weight imides that contain the same structural features that are present in polyimide materials. We have measured equation-of-state properties and dipole moments for a variety of such systems in the liquid state. Both pure compounds and binary mixtures have been studied.
Orwoll, Robert A.↗
Solar-Cycle Changes in GONG P-Mode Widths and Amplitudes 1995-1998
We search for a solar cycle variation in mode widths and amplitudes derived from 3-month GONG time series. The variation of mode width and amplitude observed in GONG data are the combined effects of fill factor, temporal variation, and measurement uncertainties. The largest variation is caused by the fill factor resulting in modes with increased width and reduced amplitude when fill is lower. We assume that the solar cycle variation is the only other systematic variation beside the temporal window function effect. We correct all currently available data sets for the fill factor and simultaneously derive the solar cycle variation. We find an increase of about 3% on average in mode width from the previous minimum to Oct. 1998 and a decrease of about 7% and 6% in mode amplitude and mode area (width x amplitude). We find no l dependence of the solar-cycle changes. As a function of frequency, these changes show a maximum between 2.7 and 3.3 mHz with about 47% higher than average values for mode width and about 29% and 36% higher ones for mode amplitude and area. We estimate the significance of these rather small changes by a pre-whitening method and find that the results are significant at or above the 99.9% level with mode area showing the highest level of significance and mode width the lowest. The variation in background amplitude is most likely not significant and is consistent with a zero change.
Komm R. W.↗
Experimental Cross Sections for Excitation of the 2s S-2 yields 2p P-2 Transition in C(3+)
Experimental cross sections are presented for excitation of the 2s yields 2p transition in C(3+). Use is made of the energy-loss method with merged beams. Also described is use of a multipole "electronic aperture" to discriminate against elastically-scattered electrons. Comparisons are made with previous experimental energy-loss and optical-emission data, and with results of several theoretical calculations.
Chutjian, A.↗
Surface States and Effective Surface Area on Photoluminescent P-Type Porous Silicon
The present study is motivated by the possibility of utilizing porous silicon for spectral sensors. Pulse measurements on the porous-Si/electrolyte system are employed to determine the surface effective area and the surface-state density at various stages of the anodization process used to produce the porous material. Such measurements were combined with studies of the photoluminescence spectra. These spectra were found to shift progressively to the blue as a function of anodization time. The luminescence intensity increases initially with anodization time, reaches a maximum and then decreases with further anodization. The surface state density, on the other hand, increases with anodization time from an initial value of about 2 x 10(exp 12)/sq cm surface to about 1013 sq cm for the anodized surface. This value is attained already after -2 min anodization and upon further anodization remains fairly constant. In parallel, the effective surface area increases by a factor of 10-30. This behavior is markedly different from the one observed previously for n-type porous Si.
Weisz, S. Z.↗
Compendium of NASA Data Base for the Global Tropospheric Experiment's Pacific Exploratory Mission - Tropics B (PEM-Tropics B): P-3B - Volume 2
This report provides a compendium of NASA aircraft data that are available from NASA's Global Tropospheric Experiment's (GTE) Pacific Exploratory Mission-Tropics B (PEM-Tropics B) conducted in March and April 1999. PEM-Tropics B was conducted during the southern-tropical wet season when the influence from biomass burning observed in PEM-Tropics A was minimal. Major deployment sites were Hawaii, Kiritimati (Christmas Island), Tahiti, Fiji, and Easter Island. The broad goals of PEM-Tropics B were to improved understanding of the oxidizing power of the atmosphere and the processes controlling sulfur aerosol formation and to establish baseline values for chemical species that are directly coupled to the oxidizing power and aerosol loading of the troposphere. The purpose of this document is to provide a representation of aircraft data that will be available in archived format via NASA Langley's Distributed Active Archive Center (DAAC) or are available through the GTE Project Office archive. The data format is not intended to support original research/analysis, but to assist the reader in identifying data that are of interest.
Scott, A. Donald, Jr.↗
Measurements of Oxygenated Organic Chemicals In the Pacific Troposphere During TRACE-P: Higher Aldehydes (less than C(sub 1)), Their Sources, and Potential Role In Atmospheric Oxidation
Airborne measurements of a large number of oxygenated organics were carried out in the Pacific troposphere (to 12 km) in the Spring of 2001 (Feb. 24-April 10). Specifically these measurements included acetaldehyde, propanaldehyde, acetone, methylethyl ketone, methanol, ethanol, PAM and organic nitrates. Independent measurements of formaldehyde, peroxides, and tracers were also available. Highly polluted as well as pristine air masses were sampled. Oxygenated organics were abundant in the clean In troposphere and were greatly enhanced in the outflow regions from Asia. Extremely high concentrations of aldehydes could be measured in the troposphere. It is not possible to explain the large abundances of aldehydes in the background troposphere without invoking significant oceanic sources. A strong correlation between the observed mixing ratios of formaldehyde and acetaldehyde is present. We infer that higher aldehydes (such as acetaldehyde and propanaldehyde) may provide a large source of formaldehyde and sequester Cox throughout the troposphere. The atmospheric behavior of acetone, methylethyl ketone, and methanol is generally indicative of their common terrestrial sources with a Image contribution from biomass/biofuel burning. A vast body of data has been collected and it is being analyzed both statistically and with the help of models to better understand the role that oxygenated organics play in the atmosphere and to unravel their sources and sinks. These results will be presented.
Singh, Hanwant B.↗