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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
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

A multiband radiometer and data acquisition system for remote sensing field research

Specifications are described for a recently developed prototype multispectral data acquisition system which consists of multiband radiometer with 8 bands between 0.4 and 12.5 micrometers and a data recording module to record data from the radometer and ancillary sources. The systems is adaptable to helicopter, truck, or tripod platforms, as well as hand-held operation. The general characteristics are: (1) comparatively inexpensive to acquire, maintain and operate; (2) simple to operate and calibrate; (3) complete with data hardware and software; and (4) well documented for use by researchers. The instrument system is to be commercially available and can be utilized by many researchers to obtain large numbers of accurate, calibrated spectral measurements. It can be a key element in improving and advancing the capability for field research in remote sensing.

Bauer, M. E.↗
NASA NTRS1982

A portable, low-cost flight-data measurement and recording system

The design of and the experience with an inexpensive, hand-portable, onboard data system used to record four parameters in the final portion of the landing approach and touchdown of an airplane are described. The system utilized a high-quality audio tape recorder and amateur photographic equipment with accessory circuitry rather than specialized instrumentation to given satisfactory results.

Miller, R. J.↗
NASA NTRS1981

Market assessment of photovoltaic power systems for agricultural applications in Colombia

The market potential for photovoltaic systems in the agricultural sector of Colombia is assessed. Consideration was given to over twenty specific livestock production, crop production, and rural services applications requiring less than 15 kW of power without backup power. Analysis revealed that near-term potential exists for photovoltaic technology in applications in coffee depulging, cattle watering, rural domestic users, rural water supply and small irrigation, rural telephones, rural health posts, and vaccine refrigeration. Market size would be in the 1200 to 2500 kWp range in the 1981 to 86 timeframe. Positive factors influencing the market size include a lack of electrical services, potential for developing the Llanos Orientales Territory, high fuel costs in remote areas, balance of system availability, the presence of wealthy land owners, and a large government-sponsored contract for photovoltaic (PV)-powered rural telephone systems. The anticipated eligibility of photovoltaic equipment for loans would be a further positive factor in market potential. Important negative factors include relatively inexpensive energy in developed locations, reliance on hydropower, lack of familiarity with PV equipment, a lack of financing, and established foreign competition in PV technology. Recommendations to American PV manufacturers attempting to develop the Colombian market are given.

Steigelmann, W.↗
NASA NTRS1981

AgRISTARS. Supporting research: MARS x-band scatterometer

The design, construction, and data collection procedures of the mobile agricultural radar sensor (MARS) x band scatterometer are described. This system is an inexpensive, highly mobile, truck mounted FM-CW radar operating at a center frequency of 10.2 GHz. The antennas, which allow for VV and VH polarizations, are configured in a side looking mode that allows for drive by data collection. This configuration shortens fieldwork time considerably while increasing statistical confidence in the data. Both internal calibration, via a delay line, and external calibration with a Luneberg lens are used to calibrate the instrument in terms of sigma(o). The radar scattering cross section per unit area, sigma(o), is found using the radar equation.

Ulaby, F. T.↗
NASA NTRS1982

Land Mobile Satellite Service (LMSS): A conceptual system design and identification of the critical technologies: Part 2: Technical report

A conceptual system design for a satellite-aided land mobile service is described. A geostationary satellite which employs a large (55-m) UHF reflector to communicate with small inexpensive user antennas on mobile vehicles is discussed. It is shown that such a satellite system through multiple beam antennas and frequency reuse can provide thousands of radiotelephone and dispatch channels serving hundreds of thousands of users throughout the U.S.

Naderi, F.↗
NASA NTRS1981

Development and validation of the V/STOL aerodynamics and stability and control manual

A V/STOL Aerodynamics and Stability and Control Manual was developed to provide prediction methods which are applicable to a wide range of V/STOL configurations in hover and transition flight, in and out of ground effect. Propulsion-induced effects have been combined with unpowered aerodynamics in a buildup of total forces and moments for the jet-lift concept, so that total aerodynamics can be used to predict aircraft stability, control, and flying qualities characteristics. Results of longitudinal aerodynamic predictions have been compared with test data, and indicate that the methods are fast, inexpensive, and within the desired accuracy for the objective preliminary design stage.

Henderson, C.↗
NASA NTRS1981

Evaluation of silicon-on-ceramic material for low-cost solar cells

The silicon-on-ceramic (SOC) process produces thin layers of silicon on inexpensive ceramic substrates. The layers are produced by unidirectional solidification of molten silicon, and are polycrystalline. Solar cells made from SOC material have performed with a conversion efficiency of 10.5%. In connection with the objective to improve the efficiency of SOC solar cells, an investigation was conducted to assess the relative importance of grain boundaries and impurities. In order to separate the two effects, light-beam-induced current (LBIC) measurements of the short-circuit current were made using a micron-sized light beam from a monochromator. The LBIC measurements are closely related to solar cell performance since the technique identifies the various spatial and spectral contributions to solar cell current. On the basis of the obtained results, it appears that structural defects are more important than chemical defects in limiting the performance of present SOC solar cells.

Zook, J. D.↗
NASA NTRS1981

Silicon solar cells with nickel/solder metallization

The use of nickel plus solder is shown to be feasible for contact metallization for silicon solar cells by offering a relatively inexpensive method of making electrical contact with the cell surfaces. Nickel is plated on silicon solar cells using an electroless chemical deposition method to give contacts with good adhesion, and in some cases where adhesion is poor initially, sintering under relatively mild conditions will dramatically improve the quality of the bond without harming the p-n junction of the cell. The cells can survive terrestrial environment stresses, which is demonstrated by a 1000 hour test at 85 C and 85% relative humidity under constant forward bias of 0.45 volt.

Petersen, R. C.↗
NASA NTRS1981

Redox storage systems for solar applications

It is noted that the worldwide development of solar photovoltaic and wind turbine systems to meet a range of terrestrial electrical energy requirements has underscored the need for inexpensive and reliable electrical energy storage. The NASA Redox Energy Storage System, based on soluble aqueous iron and chromium chloride redox couples, has exhibited many system-related features which for the most part are unique to this storage system. The technology advances required in the two elements (electrodes and membranes), which are the key to its technological feasibility, have been attained and system development has begun. The design, construction, and testing of a 1-kW system integrated with a solar photovoltaic array is underway to provide early demonstration of the attractive system-related features of the NASA Redox Storage System. Also demonstrated will be its versatility and compatibility with a terrestrial solar photovoltaic electric power system.

Hagedorn, N. H.↗
NASA NTRS1980

Open-loop nanosecond-synchronization for wideband satellite communications

A synchronization technique for use with an onboard processing satellite communication system is discussed. The satellite oscillator is used both as the system time reference and as the frequency source for all downlink carriers and data clocks. Downlink timing is established at each system earth terminal through a combination of carrier and data-clock tracking and a downlink timing epoch signal consisting of one bit per TDMA data burst. Uplink timing is established by an open-loop range prediction process using precision ephemerides calculated and distributed by the central control station. Overall timing accuracy of the uplink signal at the satellite receiver of + or - 7 nanoseconds permits unambiguous identification of each data bit position in a 128 Mbps TDMA burst. This is accomplished by means of simple, inexpensive terminal hardware using available crystal oscillators for time/frequency references and digital synthesis techniques that may be implemented in digital LSI chips.

Holmes, W. M., Jr.↗
NASA NTRS1981

A preliminary assessment of the problems in the use of interference filter photometers to determine total ozone

In the spring of 1979 an investigation was started involving the intercomparison of five ground based instruments designed to measure total ozone. The instruments considered include the Dobson spectrometer, the Russian M-83 ozonometer, the Brewer Ozone Spectrophotometer, the New Zealand (Canterbury) filter photometer, and the SenTran Company filter photometer. Three of these instruments use optical filters to make spectrophotometric determinations of total atmospheric ozone. The M-83 uses glass absorption filters to isolate the ultraviolet bands used. The Canterbury and the SenTran instruments use narrow-bandpass dielectric interference filters for the same purpose. Instruments employing optical filters are very appealing since they can be made small, rugged, and relatively inexpensive. However, the results of the reported investigation show that serious problems must be resolved before any filter instrument can be considered reliable enough for the conduction of long term, meaningful ozone measurements.

Gerlach, J. C.↗
NASA NTRS1982

Orbit determination of geosynchronous satellites by VLBI and differential VLBI

Four approaches to radio interferometric tracking of geosynchronous satellites are analyzed and compared. Quasar-based differential very-long-baseline interferometry, which requires a very sensitive receiver, can achieve meter-level position accuracy with a two-baseline system. Satellite-based differential VLBI gives somewhat lower accuracy with a compact, inexpensive receiver. Nondifferential VLBI, using less precise media and clock calibrations obtained by observing the GPS satellites, still gives 5-10 m position accuracy with two baselines. For a sufficiently inclined orbit, all interferometric approaches can yield six-component satellite state from a single baseline.

Yunck, T. P.↗
NASA NTRS1982

Digital overlay of cartographic information on Landsat MSS data for soil surveys

Cartographic soils data were digitized, spatially registered, and merged with processed Landsat image data. The Landsat Multispectral Scanner Subsystem (MSS) image data were used to generate a thematic map representing different soil surface characteristics and an enhanced image. The thematic map was generated using supervised and unsupervised classification procedures. The enhanced image was generated by performing a linear contrast stretch on data altered by a principal components transformation. Although both procedures yielded images useful for soil unit delineation, image enhancement was determined to be more suitable because it was more expedient and inexpensive. Enhanced images cost $0.06 per hectare, spectral classifications cost $0.08 per hectare. The overlay of cartographic data on Landsat data facilitates comparisons between the various processing methods used for soil unit boundary determination, delineation, and verification. This technique also provides for accurate and expedient spatial referencing for field observations and cartographic correlation.

Imhoff, M. L.↗
NASA NTRS1982

On the automatic generation of FEM models for complex gears - A work-in-progress report

A description is presented of the development and use of a preprocessor to create a NASTRAN finite element model of a complex spur, helical, or spiral bevel gear quickly, inexpensively, and accurately. The preprocessor creates a ready to run NASTRAN input deck including the executive, case control, and bulk data sections. It generates nodes and solid elements to model spur, helical, or spiral bevel gear teeth with integral shafting. Either a complete gear shafting model or a symmetric model is created. The fundamental building block of the gear model is the base layer. The base layer is the mesh configuration of one layer of one tooth segment which is in turn duplicated, translated, and rotated to create the completed model of the gear. Once the base layer is created, the construction of the finite element model is straightforward.

Drago, R. J.↗
NASA NTRS1983

Microcomputer Multiplexes Alphanumeric Labels on CRT's

External, low-power alphanumeric label generator eliminates costly video circuitry. Microprocessor-based system for multiplexing alphanumeric and analog data stores both program and data. Uses inexpensive circuits, consumes minimal current, is programmable by user, adapts to many CRT monitors. System generates 5-by-7 dot-matrix characters. System speed is adaquate for medical monitoring purposes.

Cooper, T.↗
NASA NTRS1984

Scanning XeCl Laser

Applications of narrow-bandwith laser include remote sensing and high-resolution spectroscopy. Scanning XeCl oscillator/ring-laser amplifier produces narrow spectral bandwidth (less than 0.003nm) over tuning range of 307.5 to 308.5 nm. Ring configuration has following advantages: oscillator decoupled from amplifier, output unidirectional, output beam uniform and inexpensive optics allow variable output coupling and cavity length.

Laudenslager, J. B.↗
NASA NTRS1984

Portable X-Y Scanner

Lightweight device uses one drive motor for surface scanning. Electromechanical X-Y Scanner indexed in both x and y by single motor. Constructed of readily available inexpensive parts. Used to move eddycurrent sensor over surface of metal plate; other applications for unique features include low power consumption, light weight, and portability.

Kurtz, G. W.↗
NASA NTRS1984

Antivortex Inlet Ribs for Fluid-Seals

Instability in rotating machinery reduced. Ring of ribs fastened to existing stator in turbopump pressure-seal inlet. Ribs suppress swirl in flow entering seal. Rib concept offers relatively inexpensive solution to some lateral-instability problems in many other systems with rotating pressure seals.

Chen, W. C.↗