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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 541 records · Page 30

Resonant Landau-Zener conversion in multi-axion systems

Multiple axions may emerge in the low-energy effective theory of Nature. Generically, the potentials describing these axion fields are non-diagonal, leading to mass mixing between axion states which can be temperature-dependent due to QCD instanton effects. As the temperature of the Universe drops, level crossing can occur, causing resonant conversion between axion states. In this work, we present an analytic study of the cosmological evolution of multi-axion systems including adiabatic and non-adiabatic resonant conversion from one axion state into another during the misalignment process. We show how the Landau-Zener formalism accurately captures the non-adiabatic resonant conversion, permitting an analytic description of the relic abundances of each axion field for nearly any arbitrary two-state axion mass matrix. As an application, we study the mixing of a QCD axion with an axion-like-particle for specific potentials to identify the predictions for haloscope experiments. We conclude that the detection of an axion off the expected QCD mass-coupling line predicts other haloscope targets if it mixes with the QCD axion.

Axions and ALPs↗

The use of ERTS-1 MSS data for mapping strip mines and acid mine drainage in Pennsyvania

Digital processing of ERTS-I MSS data for areas around the west branch of the Susquehanna River permits identification of stripped areas including ones that are not discernible from visual analysis of ERTS imagery. Underflight data and ground-based observations are used for ground-truth and as a basis for designing more refined operators to make sub-classifications of stripped areas, particularly with regard to manifestations of acid mine drainage; because of associated diagnostic effects on vegetation, seasonal changes in classifiction criteria are being documented as repeated, cloud-free ERTS-I coverage of the same area becomes available. Preliminary results indicate that ERTS data can be used to moniter not only the total extent of stripping in given areas but also the effectiveness of reclamation and pollution abatement procedures.

Alexander, S. S.↗

Investigation and evaluation of shuttle/GPS navigation system

Iterative procedures were used to analyze the performance of two preliminary shuttle/GPS navigation system configurations: an early OFT experimental system and a more sophisticated system which consolidates several separate navigation functions thus permitting net cost savings from decreased shuttle avionics weight and power consumption, and from reduced ground data processing. The GPS system can provide on-orbit navigation accuracy an order of magnitude better than the baseline system, with very adequate link margins. The worst-case link margin is 4.3 dB. This link margin accounts for shuttle RF circuit losses which were minimized under the constraints of program schedule and environmental limitations. Implicit in the link analyses are the location trade-offs for preamplifiers and antennas.

Nilsen, P. W.↗

Industrial ion source technology

In reactive ion etching of Si, varying amounts of O2 were added to the CF4 background. The experimental results indicated an etch rate less than that for Ar up to an O2 partial pressure of about .00006 Torr. Above this O2 pressure, the etch rate with CF4 exceeded that with Ar alone. For comparison the random arrival rate of O2 was approximately equal to the ion arrival rate at a partial pressure of about .00002 Torr. There were also ion source and ion pressure gauge maintenance problems as a result of the use of CF4. Large scale (4 sq cm) texturing of Si was accomplished using both Cu and stainless steel seed. The most effective seeding method for this texturing was to surround the sample with large inclined planes. Designing, fabricating, and testing a 200 sq cm rectangular beam ion source was emphasized. The design current density was 6 mA/sq cm with 500 eV argon ions, although power supply limitations permitted operation to only 2 mA/sq cm. The use of multiple rectangular beam ion sources for continuous processing of wider areas than would be possible with a single source was also studied. In all cases investigated, the most uniform coverage was obtained with 0 to 2 cm beam overlay. The maximum departure from uniform processing at optimum beam overlap was found to be +15%.

Kaufman, H. R.↗

Tethered Satellite System (TSS) core equipment

To date, three Tethered Satellite System (TSS) missions of the Italian provided scientific satellite orbiting in the ionosphere connected to U.S. Space Shuttle is foreseen. The first mission will use an electrically conductive tether of 20 km deployed upward from the orbiter flying at 300 km altitude. This mission will allow investigation of the TSS electrodynamic interaction with the ionosphere due to the high voltage induced across the two terminators of the system during its motion throughout the geomagnetic field. The second mission will use a dielectric tether of 100 km deployed downward from the Orbiter flying at 230 km altitude. Tethered-vehicle access to altitude as low as 120 to 150 km from the Orbiter would permit direct long term observation of phenomena in the lower thermosphere and determination of other dynamical physical processes. The third mission would use the same configuration of the first electrodynamic mission with the complete Core Equipment. Study of power generation by tethered systems would be possible by operating the Core Equipment in the inverted current mode. This mode of operation would allow ion current collection upon the TSS satellite by controlling its potential with respect to the ambient ionospheric plasma. The main requirements of the Core Equipment configuration to date foreseen for the first TSS electrodynamic mission is described. Besides the Core Equipment purposes, its hardware and operational sub-modes of operation are described.

Bonifazi, C.↗

A theoretical formulation of wave-vortex interactions

A unified theoretical formulation for wave-vortex interaction, designated the '(omega, Pi) framework,' is presented. Based on the orthogonal decomposition of fluid dynamic interactions, the formulation can be used to study a variety of problems, including the interaction of a longitudinal (acoustic) wave and/or transverse (vortical) wave with a main vortex flow. Moreover, the formulation permits a unified treatment of wave-vortex interaction at various approximate levels, where the normal 'piston' process and tangential 'rubbing' process can be approximated dfferently.

Wu, J. Z.↗

Method of resolving radio phase ambiguity in satellite orbit determination

For satellite orbit determination, the most accurate observable available today is microwave radio phase, which can be differenced between observing stations and between satellites to cancel both transmitter- and receiver-related errors. For maximum accuracy, the integer cycle ambiguities of the doubly differenced observations must be resolved. To perform this ambiguity resolution, a bootstrapping strategy is proposed. This strategy requires the tracking stations to have a wide ranging progression of spacings. By conventional 'integrated Doppler' processing of the observations from the most widely spaced stations, the orbits are determined well enough to permit resolution of the ambiguities for the most closely spaced stations. The resolution of these ambiguities reduces the uncertainty of the orbit determination enough to enable ambiguity resolution for more widely spaced stations, which further reduces the orbital uncertainty. In a test of this strategy with six tracking stations, both the formal and the true errors of determining Global Positioning System satellite orbits were reduced by a factor of 2.

Councelman, Charles C., III↗

Science applications of the Mars Observer gamma ray spectrometer

The Mars Observer gamma ray spectrometer will return data related to the elemental composition of Mars. The instrument has both a gamma ray spectrometer and several neutron detectors. The gamma ray spectrometer will return a spectrum nominally every 20 s from Mars permitting a map of the elemental abundances to be made. The gamma rays are emitted from nuclei involved in radioactive decay, from nuclei formed by capture of a thermal neutron, and from nuclei put in an excited state by a fast-neutron interaction. The gamma rays come from an average depth of the order of a few tens of centimeters. The spectrum will show sharp emission lines whose intensity determines the concentration of the element and whose energy identifies the element. The neutron detectors, using the fact that the orbital velocity of the Mars Observer spacecraft is similar to the velocity of thermal neutrons, determine both the thermal and epithermal neutron flux. By combining the results from both techniques it is possible to map the depth dependence of hydrogen in the upper meter as well. These data permit a variety of Martian geoscience problems to be addressed including the crust and mantle composition, weathering processes, volcanism, and the volatile reservoirs and processes.

Boynton, W. V.↗

NASA's New Technology Reporting System: A Review and Future Prospects

This report represents a systematic effort to describe how NASA's new technology reporting system operates today, and how that system might be enhanced. Although the system has run for more than two decades, it is not well documented in terms of organization, operational practices, or other program benchmarks. The study seeks to identify and assess incentives or disincentives to reporting, program management, program follow through, and the feasibility of various means for improving the general process. Initially, it was hoped that the study team might uncover the kind of information that would permit the determination of some 'average' sequence of events (or a time line) from the point of identifying a solution to technical 'need' to the point where its solution was actually reported to NASA. Information regarding this objective proved to be too elusive, primarily because early probes revealed that con- tractor awareness of the new technology requirements generally was too poor to provide useful information. The report that follows is based primarily upon documents furnished by NASA Headquarters, by Field Center technology utilization officers, and interviews with persons knowledgeable about the system. Visits were made to seven Field Centers: Ames Research Center, Goddard Space Flight Center, Jet Propulsion Laboratory, Johnson Space Center, Langley Research Center, Lewis Research Center, and Marshall Space Flight Center. Other documents were furnished by officials of major aerospace corporations. Detailed interviews were conducted with Field Center technology utilization officials, project engineers or scientists, patent counsels, and other Field Center officials who had knowledge about the new technology reporting system. Interviews also were conducted with knowledgeable officials from a number of the primary aerospace companies. Numeric data was obtained from regular NASA reports, from original sources such as, NASA Tech Briefs, or from contractor reports. I am indebted to dozens of persons in both NASA and industry who took time to assist in the data collection by being interviewed, and through answering follow up questions on the telephone. Individuals interviewed and their affiliations are shown in Appendix A. I am most grateful to them for their kind assistance. A note of thanks is due to the other members of the DRI study team: Jody Briles, Kathy Hirst, and Joel Johnson. The responsibility for this report, its accuracy, and the nature of the observations and conclusions rest solely with the author. Text or citations in the numbered footnotes are to be found at the end of each chapter.

Chapman, Richard L.↗

Bond Sensitivity to Silicone Contamination

Currently during fabrication of the Space Shuttle booster rocket motors, the use of silicone and silicone-containing products is prohibited in most applications. Many shop aids and other materials containing silicone have the potential, if they make contact with a bond surface, to transfer some of the silicone to the substrates being bonded. Such transfer could result in a reduction of the bond strength or even failure of the subsequent bonds. This concern is driving the need to understand the effect of silicones and the concentration needed to affect a given bond-line strength. Additionally, as silicone detection methods used for materials acceptance improve what may have gone unnoticed earlier is now being detected. Thus, realistic silicone limits for process materials (below which bond performance is satisfactory) are needed rather than having an absolute no silicone permitted policy.

Caldwell, G. A.↗

Grid Technology as a Cyberinfrastructure for Delivering High-End Services to the Earth and Space Science Community

Grid technology consists of middleware that permits distributed computations, data and sensors to be seamlessly integrated into a secure, single-sign-on processing environment. In &is environment, a user has to identify and authenticate himself once to the grid middleware, and then can utilize any of the distributed resources to which he has been,panted access. Grid technology allows resources that exist in enterprises that are under different administrative control to be securely integrated into a single processing environment The grid community has adopted commercial web services technology as a means for implementing persistent, re-usable grid services that sit on top of the basic distributed processing environment that grids provide. These grid services can then form building blocks for even more complex grid services. Each grid service is characterized using the Web Service Description Language, which provides a description of the interface and how other applications can access it. The emerging Semantic grid work seeks to associates sufficient semantic information with each grid service such that applications wii1 he able to automatically select, compose and if necessary substitute available equivalent services in order to assemble collections of services that are most appropriate for a particular application. Grid technology has been used to provide limited support to various Earth and space science applications. Looking to the future, this emerging grid service technology can provide a cyberinfrastructures for both the Earth and space science communities. Groups within these communities could transform those applications that have community-wide applicability into persistent grid services that are made widely available to their respective communities. In concert with grid-enabled data archives, users could easily create complex workflows that extract desired data from one or more archives and process it though an appropriate set of widely distributed grid services discovered using semantic grid technology. As required, high-end computational resources could be drawn from available grid resource pools. Using grid technology, this confluence of data, services and computational resources could easily be harnessed to transform data from many different sources into a desired product that is delivered to a user's workstation or to a web portal though which it could be accessed by its intended audience.

Hinke, Thomas H.↗

Web Exploration Tools for a Fast Federated Optical Survey Database

We implemented several new web-based tools to improve the efficiency and versatility of access to the APS Catalog of the POSS I (Palomar Observatory-National Geographic Sky Survey) and its associated image database. The most important addition was a federated database system to link the APS Catalog and image database into one Internet-accessible database. With the FDBS, the queries and transactions on the integrated database are performed as if it were a single database. We installed Myriad the FDBS developed by Professor Jaideep Srivastava and members of his group in the University of Minnesota Computer Science Department. It is the first system to provide schema integration, query processing and optimization, and transaction management capabilities in a single framework. The attached figure illustrates the Myriad architecture. The FDBS permits horizontal access to the data, not just vertical. For example, for the APS, queries can be made not only by sky position, but also by any parameter present in either of the databases. APS users will be able to produce an image of all the blue galaxies and stellar sources for comparison with x-ray source error ellipses from AXAF (X Ray Astrophysics Facility) (Chandra) for example. The FDBS is now available as a beta release with the appropriate query forms at our web site. While much of our time was occupied with adapting Myriad to the APS environment, we also made major changes in Star Base, our DBMS for the Catalog, at the web interface to improve its efficiency for issuing and processing queries. Star Base is now three times faster for large queries. Improvements were also made at the web end of the image database for faster access; although work still needs to be done to the image database itself for more efficient return with the FDBS. During the past few years, we made several improvements to the database pipeline that creates the individual plate databases queries by StarBase. The changes include improved positions especially for galaxies, using a new median centroider and integrated magnitudes for galaxies with an improved density-to-intensity calibration with a "sky" background subtraction. In the original version of StarBase the object classification fainter than 19.5-20.0 mag., was an extrapolation of the networks trained on brighter objects. We have used a new catalog of galaxies at the NGP to train a neural network on objects fainter than 20th mag. This improved classification is used in the new version of StarBase. We have also added a FITS table option for the returned data from queries on the object catalog. The APS image database includes images in both colors so we have added a tool for querying the image database in both colors simultaneously. The images can be displayed in parallel or blinked for comparison.

Humphreys, Roberta M.↗

Analysis of edible oil processing options for the BIO-Plex advanced life support system

Edible oil is a critical component of the proposed plant-based Advanced Life Support (ALS) diet. Soybean, peanut, and single-cell oil are the oil source options to date. In terrestrial manufacture, oil is ordinarily extracted with hexane, an organic solvent. However, exposed solvents are not permitted in the spacecraft environment or in enclosed human tests by National Aeronautics and Space Administration due to their potential danger and handling difficulty. As a result, alternative oil-processing methods will need to be utilized. Preparation and recovery options include traditional dehulling, crushing, conditioning, and flaking, extrusion, pressing, water extraction, and supercritical extraction. These processing options were evaluated on criteria appropriate to the Advanced Life Support System and BIO-Plex application including: product quality, product stability, waste production, risk, energy needs, labor requirements, utilization of nonrenewable resources, usefulness of by-products, and versatility and mass of equipment to determine the most appropriate ALS edible oil-processing operation.

NASA Discipline Life Support Systems↗

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.↗

Laser induced photoluminiscence studies of primary photochemical production processes of cometary radicals

A tunable vacuum ultraviolet flash lamp was constructed. This unique flash lamp was coupled with a tunable dye laser detector and permits the experimenter to measure the production rates of ground state radicals as a function of wavelength. A new technique for producing fluorescent radicals was discovered. This technique called multiphoton ultraviolet photodissociation is currently being applied to several problems of both cometary and stratospheric interest. It was demonstrated that NO2 will dissociate to produce an excited fragment and the radiation can possibly be used for remote detection of this species.

Jackson, W. M.↗

An automated process sequence using preformed cell contacts and interconnects with a total cost of $0.64 per peak watt in 1986

A process sequence is described which utilizes a preformed metal mesh electrostatically bonded to each cell to provide the front contact. Cells of 12 percent AM1 efficiency have been produced using this scheme. This method also permits access to both contacts on the cell from the back side. In addition, low cost cell interconnection is accomplished using a flexible 'printed circuit' sheet which is ultrasonically bonded to the cell contacts. The complete process sequence as well as automated equipment which also uses ion implantation and pulse annealing is described. The total cost for module fabrication is estimated at $0.64 per peak watt for a 30 MW/year plant.

Armini, A. J.↗

Wide-bandwidth high-resolution search for extraterrestrial intelligence

A third antenna was added to the system. It is a terrestrial low-gain feed, to act as a veto for local interference. The 3-chip design for a 4 megapoint complex FFT was reduced to finished working hardware. The 4-Megachannel circuit board contains 36 MByte of DRAM, 5 CPLDs, the three large FFT ASICs, and 74 ICs in all. The Austek FDP-based Spectrometer/Power Accumulator (SPA) has now been implemented as a 4-layer printed circuit. A PC interface board has been designed and together with its associated user interface and control software allows an IBM compatible computer to control the SPA board, and facilitates the transfer of spectra to the PC for display, processing, and storage. The Feature Recognizer Array cards receive the stream of modulus words from the 4M FFT cards, and forward a greatly thinned set of reports to the PC's in whose backplane they reside. In particular, a powerful ROM-based state-machine architecture has been adopted, and DRAM has been added to permit integration modes when tracking or reobserving source candidates. The general purpose (GP) array consists of twenty '486 PC class computers, each of which receives and processes the data from a feature extractor/correlator board set. The array performs a first analysis on the provided 'features' and then passes this information on to the workstation. The core workstation software is now written. That is, the communication channels between the user interface, the backend monitor program and the PC's have working software.

Horowitz, Paul↗

Bonded Lubricants

Another spinoff to the food processing industry involves a dry lubricant developed by General Magnaplate Corp. of Linden, N.J. Used in such spacecraft as Apollo, Skylab and Viking, the lubricant is a coating bonded to metal surfaces providing permanent lubrication and corrosion resistance. The coating lengthens equipment life and permits machinery to be operated at greater speed, thus increasing productivity and reducing costs. Bonded lubricants are used in scores of commercia1 applications. They have proved particularly valuable to food processing firms because, while increasing production efficiency, they also help meet the stringent USDA sanitation codes for food-handling equipment. For example, a cookie manufacturer plagued production interruptions because sticky batter was clogging the cookie molds had the brass molds coated to solve the problem. Similarly, a pasta producer faced USDA action on a sanitation violation because dough was clinging to an automatic ravioli-forming machine; use of the anti-stick coating on the steel forming plates solved the dual problem of sanitation deficiency and production line downtime.

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