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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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At least 109 records · Page 6

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NASA NTRS1992

USRA/RIACS

The Research Institute for Advanced Computer Science (RIACS) was established by the Universities Space Research Association (USRA) at the NASA Ames Research Center (ARC) on June 6, 1983. RIACS is privately operated by USRA, a consortium of universities with research programs in the aerospace sciences, under a cooperative agreement with NASA. The primary mission of RIACS is to provide research and expertise in computer science and scientific computing to support the scientific missions of NASA ARC. The research carried out at RIACS must change its emphasis from year to year in response to NASA ARC's changing needs and technological opportunities. A flexible scientific staff is provided through a university faculty visitor program, a post doctoral program, and a student visitor program. Not only does this provide appropriate expertise but it also introduces scientists outside of NASA to NASA problems. A small group of core RIACS staff provides continuity and interacts with an ARC technical monitor and scientific advisory group to determine the RIACS mission. RIACS activities are reviewed and monitored by a USRA advisory council and ARC technical monitor. Research at RIACS is currently being done in the following areas: (1) parallel computing; (2) advanced methods for scientific computing; (3) learning systems; (4) high performance networks and technology; and (5) graphics, visualization, and virtual environments. In the past year, parallel compiler techniques and adaptive numerical methods for flows in complicated geometries were identified as important problems to investigate for ARC's involvement in the Computational Grand Challenges of the next decade. We concluded a summer student visitors program during this six months. We had six visiting graduate students that worked on projects over the summer and presented seminars on their work at the conclusion of their visits. RIACS technical reports are usually preprints of manuscripts that have been submitted to research journals or conference proceedings. A list of these reports for the period July 1, 1992 through December 31, 1992 is provided.

Oliger, Joseph↗

NASA NTRS1993

Ultra-high resolution water window x ray microscope optics design and analysis

This project has been focused on the design and analysis of an ultra-high resolution water window soft-x-ray microscope. These activities have been accomplished by completing two tasks contained in the statement of work of this contract. The new results from this work confirm: (1) that in order to achieve resolutions greater than three times the wavelength of the incident radiation, it will be necessary to use spherical mirror surfaces and to use graded multilayer coatings on the secondary in order to accommodate the large variations of the angle of incidence over the secondary when operating the microscope at numerical apertures of 0.35 or greater; (2) that surface contour errors will have a significant effect on the optical performance of the microscope and must be controlled to a peak-to-valley variation of 50-100 A and a frequency of 8 periods over the surface of a mirror; and (3) that tolerance analysis of the spherical Schwarzschild microscope has been shown that the water window operations will require 2-3 times tighter tolerances to achieve a similar performance of operations with 130 A radiation. These results have been included in a manuscript included in the appendix.

Shealy, David L.↗

NASA NTRS1993

Data management in NOAA

The NOAA archives contain 150 terabytes of data in digital form, most of which are the high volume GOES satellite image data. There are 630 data bases containing 2,350 environmental variables. There are 375 million film records and 90 million paper records in addition to the digital data base. The current data accession rate is 10 percent per year and the number of users are increasing at a 10 percent annual rate. NOAA publishes 5,000 publications and distributes over one million copies to almost 41,000 paying customers. Each year, over six million records are key entered from manuscript documents and about 13,000 computer tapes and 40,000 satellite hardcopy images are entered into the archive. Early digital data were stored on punched cards and open reel computer tapes. In the late seventies, an advanced helical scan technology (AMPEX TBM) was implemented. Now, punched cards have disappeared, the TBM system was abandoned, most data stored on open reel tapes have been migrated to 3480 cartridges, many specialized data sets were distributed on CD ROM's, special archives are being copied to 12 inch optical WORM disks, 5 1/4 inch magneto-optical disks were employed for workstation applications, and 8 mm EXABYTE tapes are planned for major data collection programs. The rapid expansion of new data sets, some of which constitute large volumes of data, coupled with the need for vastly improved access mechanisms, portability, and improved longevity are factors which will influence NOAA's future systems approaches for data management.

Callicott, William M.↗

NASA NTRS1992

Airborne wavemeter validation and calibration

This manuscript outlines a continuing effort to validate and verify the performance of an airborne autonomous wavemeter for tuning solid state lasers to a desired wavelength. The application is measuring the vertical profiles of atmospheric water vapor using a differential absorption lidar (DIAL) technique. Improved wavemeter performance data for varying ambient temperatures are presented. This resulted when the electronic grounding and shielding were improved. The results with short pulse duration lasers are also included. These lasers show that similar performance could be obtained with lasers operating in the continuous and the pulsed domains.

Goad, Joseph H., Jr.↗

NASA NTRS1991

Progress in understanding the renormalization group skewness and kappa-epsilon models

The immediate goal is to understand and validate the Yakhot-Orszag model of the velocity-derivative skewness and model equation for the rate of energy dissipation epsilon. A summary of a more detailed manuscript in preparation is presented. The purpose is to clarify some limitations of the theory by careful examination of key assumptions and approximations, and thereby to encourage its improvement.

Smith, Leslie M.↗

NASA NTRS1991

An overview of the text propagation effects for land-mobile-satellite systems: Experimental and modeling results

We present an overview of the contents of the text having the above title and which is now in the form of a preliminary document titled, 'Propagation Handbook for Land-Mobile-Satellite Systems-Preliminary.' At this writing the text is undergoing peer review, and the final revised manuscript will be published in the near future as a NASA document. The text was inspired by a series of Land-Mobile-Satellite System (LMSS) experiments by the authors and other investigators at UHF and L-Band. The rationale for its writing is to place in a single document an overview of the previous propagation related salient experimental and modeling results pertaining to LMSS scenarios. It is apparent that LMSS propagation at UHF and L-Band can be seriously degraded because of attenuation (e.g., greater than 10 dB) caused by roadside tree shadowing. The extent of attenuation is shown to depend on such factors at the elevation angle to the satellite, the bearing of the line-of-signt path to the satellite relative to the line of roadside trees, the side of the road in which the vehicle is driven, the season, and the frequency. Multipath effects during line-of-sight communications are shown to cause less serious fading (e.g., smaller than 3 dB for 90 percent of the driving distance).

Goldhirsh, Julius↗

NASA NTRS1993

The analysis of global cloud and radiation data for the study of cloud-climate interactions

During the past year, ISCCP C1 data has been analyzed for two regions, the stratocumulus area off California and the tropical Atlantic. The first part of the study dealing with stratocumulus clouds is complete and the results form the technical portion of this report. A manuscript that has recently been prepared covering this subject is attached as an Appendix. The abstract describes the key finding that cloudy mean liquid water path (LWP) is invariant with cloud fraction for cloud cover between 20% - 80%. Similar conclusions are reached with ISCCP and LANDSAT data. This has important implications for General Circulation Models. A possible application is described in the Discussion section of the Appendix. An idea that has been proposed for dealing with GCM hydrology can be used.

HARSHVARDHAN↗

NASA NTRS1993

In situ detection of tropospheric OH, HO2, NO2, and NO by laser-induced fluorescence in detection chambers at reduced pressures

This report is a brief summary of the status of work on the grant entitled 'In situ detection of tropospheric OH, HO2, NO2, and NO by laser induced fluorescence in detection chambers at low pressures.' The basic instrument characteristics have been established, and have been reported in a manuscript, included as an appendix to this report, that has been accepted by the Journal of Geophysical Research. Currently, two efforts are under way. First, instrument tests and calibrations are continuing. These efforts include field measurements and an informal inter comparison in Colorado last August and September. Second, new technologies in lasers and detectors are being implemented to make the instrument smaller, lighter, and more energy efficient. Such instrument modifications are essential for measurements from aircraft, high scaffolding in forests, and ships.

Brune, William H.↗

NASA NTRS1994

Experimental study of lunar and SNC (Mars) magmas

The overall objectives of this research were to evaluate the role of C-O-S-Cl degassing processes in explaining vesiculation, oxidation state and fire-fountaining of lunar magmas by analysis of individual lunar glass spherules, and by experimental determination of equilibrium abundances and diffusion rates of C, S and Cl melt species in lunar glass compositions; and to determine possible primitive SNC magma compositions and the mineralogy of the mantle from which they were derived, and to evaluate P, T, XH2O etc. conditions at which they crystallize to form the SNC meteorites. After funding for one year, a project on the A15 volcanic green glass has been completed to the point of writing a first manuscript. Carbon-oxygen species C-O and CO2 are below detection limits (20 ppm) in these glasses, but there is up to 500 ppm S with concentrations both increasing and decreasing toward the spherule margins. Calculations and modeling indicate that C species could have been present in the volcanic gases, however. In a second project, experiments with low PH2O have resulted in refined estimates of the early intercumulus melt composition in the Chassigny meteorite which is generally accepted as a sample from Mars.

Rutherford, Malcolm J.↗

NASA NTRS1994

Reanalysis of Mariner 9 UV Spectrometer Data for Ozone, Cloud, and Dust Abundances, and Their Interaction Over Climate Timescales

Mariner 9 UV spectrometer data have been reinverted for the ozone abundance. The spectra were fit by models which covered the full range in observed solar zenith angle, cloud, dust and ozone amount, ice albedo and look angles. Errors in ozone retrieval with this data are tabulated over a range in theses conditions and are shown graphically. This work shows that significant underestimation of ozone occurred in earlier analysis of Mariner 9 data, and that much of the observed variability in Mars ozone is due to masking of ozone by clouds and dust. An in-situ measurement by balloon is recommended as it is the only technique capable of accurately inferring the ozone abundance in all conditions. Recommendations for future research are also presented. 7 manuscripts have been published in refereed journals, and three are in review. A review of these publications and presentations is in the report.

Lindner, Bernhard Lee↗

NASA NTRS1994

Muscular activity and its relationship to biomechanics and human performance

The purpose of this manuscript is to address the issue of muscular activity, human motion, fitness, and exercise. Human activity is reviewed from the historical perspective as well as from the basics of muscular contraction, nervous system controls, mechanics, and biomechanical considerations. In addition, attention has been given to some of the principles involved in developing muscular adaptations through strength development. Brief descriptions and findings from a few studies are included. These experiments were conducted in order to investigate muscular adaptation to various exercise regimens. Different theories of strength development were studied and correlated to daily human movements. All measurement tools used represent state of the art exercise equipment and movement analysis. The information presented here is only a small attempt to understand the effects of exercise and conditioning on Earth with the objective of leading to greater knowledge concerning human responses during spaceflight. What makes life from nonliving objects is movement which is generated and controlled by biochemical substances. In mammals. the controlled activators are skeletal muscles and this muscular action is an integral process composed of mechanical, chemical, and neurological processes resulting in voluntary and involuntary motions. The scope of this discussion is limited to voluntary motion.

Ariel, Gideon↗

NASA NTRS1993

NCDC mass storage systems and technologies

National Climatic Data Center (NCDC) data management issues are discussed, such as nature of holdings, history of the site, popularity of data sets, media/technology used for storage, volume distributed per month, mode of distribution, most frequently encountered problems, type of media requested/used, and evolution of media. Current holdings at NCDC are 107.8 terabytes of digital data and about 0.3 terabytes of manuscript data. The nexrad radar system is expected to generate approximately 88 terabytes per year by 1996.

Davis, Dick↗

NASA NTRS1994

Completing below-ground carbon budgets for pastures, recovering forests, and mature forests of Amazonia

The objective of this grant was to complete below-ground carbon budgets for pastures and forest soils in the Amazon. Profiles of radon and carbon dioxide were used to estimate depth distribution of CO2 production in soil. This information is necessary for determining the importance of deep roots as sources of carbon inputs. Samples were collected for measuring root biomass from new research sites at Santana de Araguaia and Trombetas. Soil gases will be analyzed for CO2 and (14)CO2, and soil organic matter will be analyzed for C-14. Estimates of soil texture from the RADAMBRASIL database were merged with climate data to calculate soil water extraction by forest canopies during the dry season. In addition, a preliminary map of areas where deep roots are needed for deep soil water was produced. A list of manuscripts and papers prepared during the reporting periods is given.

Davidson, Eric A.↗

NASA NTRS1994

Development of nonintrusive, scatter-independent techniques for measurement of liquid density inside dense sprays

A nonintrusive optical technique for measuring the liquid density in sprays used to simulate LOX injector flows is under development. This manuscript is a report on work toward that development which is currently in progress. The technique is a scatter-independent, absorption-based approach which depends on the numerical inversion of a collection of absorption profiles. For the case in which visible radiation passes through liquid-gas interfaces so numerous in sprays, substantial reductions and alterations in the signal result from scattering even in the absence of absorption. To avoid these problems, X-Rays will be used as the absorbed radiation. The experimental process is simulated by integrating the absorption spectrum for a known distribution, adding instrument noise to this 'measurement', creating a projection from the 'measurement', filtering the projection, inverting the projection, and comparing the results with the original prescribed distribution.

Hartfield, Roy↗

NASA NTRS1994

Activities of the Research Institute for Advanced Computer Science

Oliger, Joseph↗

NASA NTRS1995

Collected Papers on Wind Turbine Technology

R and D projects on electricity generating wind turbines were conducted at the NASA Lewis Research Center from 1973 to 1988. Most projects were sponsored by the U.S. Department of Energy (DOE), a major element of its Federal Wind Energy Program. Another large wind turbine project was by the Bureau of Reclamation of the U.S. Department of Interior (DOI). From 1988 to 1995, NASA wind energy activities have been directed toward the transfer of technology to commercial and academic organizations. As part of these technology transfer activities, previously unpublished manuscripts have been assembled and presented here to share the wind turbine research results with the wind energy community. A variety of wind turbine technology topics are discussed: Wind and wake models; Airfoil properties; Structural analysis and testing; Control systems; Variable speed generators; and acoustic noise. Experimental and theoretical results are discussed.

Spera, David A.↗

NASA NTRS1995

The design and development of a third generation OSEE instrument

Optically Stimulated Electron Emission (OSEE) has been used to quantify surface contamination in the aerospace community. As advances are made towards the understanding of OSEE, it is desirable to incorporate technological advances with succeeding generations of instrumentation, so that improvements in the practical application of OSEE may be disseminated among the user community. Several studies undertaken by Yost, Welch, Abedin and others have expanded the knowledge base related to the underlying principles of OSEE. The conclusions of these studies, together with inputs from the user community were the foundation upon which the development of a third generation OSEE instrument was based. This manuscript describes the significant improvements incorporated into a third generation OSEE instrument as well as the elements unique to its design.

Perey, D. F.↗

NASA NTRS1995

Discrimination of alkalinity in granitoid Rocks: A potential TIMS application

In mineral exploration, the ability to distinguish and map petrochemical variations of magmatic rocks can be a useful reconnaissance tool. Alkalinity is one such petrochemical parameter and is used in the characterization of granitoid rocks. In quartz normative plutonic rocks, alkalinity is related to the composition and abundance of feldspars. Together with quartz abundance, knowledge of feldspar modes allows the classification of these igneous rocks according to the Streckeisen diagram. Alternative classification schemes rely on whole rock geochemistry instead of mineral identifications. The relative ease of obtaining whole rock analyses means that geochemical classifications tend to be favored in exploration geology. But the technique of thermal infrared spectroscopy of rocks yields information on mineralogy and is one that can be applied remotely. The goal of the current work then is to establish whether data from TIMS can be used to distinguish the mineralogical variations that relate to alkalinity. An ideal opportunity to test this thesis arises from the work presented in a paper by Dewitt (1989). This paper contains the results of mapping and analysis of Proterozoic plutonic rocks in north-central Arizona. The map resulting from this work delineates plutons according to alkalinity in an effort to establish a trend or polarity in the regional magmatism. Also contained within this paper are brief descriptions of the mineralogy of half of the region's plutons. This combination of mineralogical and geochemical information was the rationale behind choosing this area as a site for TIMS over flights. A portion of the region centered on the northern Bradshaw Mountains was selected because it contains plutons of all three alkalinity classifications (alkali-calcic, calc-alkalic, and calic) present on DeWitt's map within a relatively small area. The site was flown in August of 1994 and the data received a few days before the writing of this manuscript. Most of this paper is devoted to the description of laboratory based spectroscopy and spectral simulations. These are required to gain insight into the correct procedures for enhancing the relatively small differences in the low spectral resolution TIMS data.

Ruff, Steven W.↗