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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 1,387 records · Page 77
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

A computer package for the design and eigenproblem solution of damped linear multidegree of freedom systems

Systems described by the matrix differental equation are considered. An interactive design routine is presented for positive definite mass, damping, and stiffness matrices. Designing is accomplished by adjusting the mass, damping, and stiffness matrices to obtain a desired oscillation behavior. The algorithm also features interactively modifying the physical structure of the system, obtaining the matrix structure and a number of other system properties. In case of a general system, where the M, C, and K matrices lack any special properties, a routine for the eigenproblem solution of the system is developed. The latent roots are obtained by computing the characteristic polynomial of the system and solving for its roots. The above routines are prepared in FORTRAN IV and prove to be usable for the machines with low core memory.

Ahmadian, M.↗
NASA NTRS1981

Gallium arsenide solar cells-status and prospects for use in space

Gallium Arsenide solar cells now equal or surpass the ubiquitous silicon solar cells in efficiency, radiation resistance, annealability, and in the capability for producing usable power output at elevated temperatures. NASA has developed a long-range research and development program to capitalize on these manifold advantages. In this paper we review the current state and future prospects for R&D in this promising solar cell material, and indicate the progress being made toward development of GaAs cells suitable for a variety of space missions. Results are presented from studies which demonstrate conclusively that GaAs cells can provide a net mission cost and weight savings for certain important mission classes.

Brandhorst, H. W.↗
NASA NTRS1980

Simplicity in command and control systems - A human factors consideration

The importance of simplicity in the man computer interface (MCI) is stressed because of the effect it has on the system containing the MCI. Results are used from an MCI study at the Jet Propulsion Laboratory to find an area where the system MCIs can be simplified. The circumstances under which these simplifications are appropriate are listed. The concepts of cognitive simplicity and process simplicity are presented as design alternatives for the MCI. In addition, the concepts of understandability, operation, learnability, level of learning, and usability are presented as tools for the system designer. The use of these concepts in developing a systematic MCI design is discussed.

Chafin, R. L.↗
NASA NTRS1982

An efficient low- and moderate-resolution spectrograph for the Hale telescope

A new low-to-moderate resolution spectrograph has been designed and built for the Cassegrain focus of the Hale 5.08-meter telescope. To maximize efficiency, resolution, and wavelength coverage the light is divided into two spectra regions by a dichroic filter behind the entrance slit, after which there are two completely separate spectrographs. The blue spectrograph operates from 3200 A to 5200 A while the red one goes from 5200 A to 10,000 A. The red detector is an 800 x 800 TI CCD while the blue detector is a 320 x 512 RCA CCD or a Shectrograph image pulse-counting system. A Boksenberg IPCS can also be mounted on the blue camera. The overall efficiency of the Cassegrain telescope, spectrographs, and CCD's combined, ranges from 5 percent to 13 percent between 3600 A and 8200 A. The spectrograph is usable from 3200 A to 10,400 A.

Oke, J. B.↗
NASA NTRS1983

Hiding Solar-Array Bus Bars

End terminals mounted under cells, maximizing usable illuminated area. Reconfigured solar panel bus bars placed under cells, reducing portion of module area not occupied by active silicon. Underside of last cell in string of cells serves as contact for positive bus. Negative tab of last cell in string is wrapped around from top of cell. Tabs are connected to output boards mounted under cells.

Hufnagel, W. F.↗
NASA NTRS1983

Lightweight, Economical Device Alleviates Drop Foot

Corrective apparatus alleviates difficulties in walking for victims of drop foot. Elastic line attached to legband provides flexible support to toe of shoe. Device used with flat (heelless) shoes, sneakers, crepe-soled shoes, canvas shoes, and many other types of shoes not usable with short leg brace.

Deis, B. C.↗
NASA NTRS1982

An interactive review system for NASTRAN

An interactive review system that addresses the problems of model display, model error checking, and postprocessing is described. The menu driven system consists of four programs whose advantages and limitations are detailed. The interface between NASTRAN and MOVIE-BYU, the modifications required to make MOVIE usable in a finite element context, and the resulting capabilities of MOVIE as a graphics postprocessor for NASTRAN are illustrated.

Durocher, L. L.↗
NASA NTRS1983

Results from tests, with van-mounted sensor, of magnetic leader cable for aircraft guidance during roll-out and turnoff

Tests were conducted with a van mounted experimental magnetic leader cable sensor to evaluate its potential for measuring aircraft displacement and heading with respect to the leader cable during roll out and turnoff. Test results show that the system may be usable in measuring displacement but the heading measurement contains errors introduced by distortion of the magnetic field by the metal van or aircraft.

Young, J. C.↗
NASA NTRS1981

The integration of a LANDSAT analysis capability with a geographic information system

The integration of LANDSAT data was achieved through the development of a flexible, compatible analysis tool and using an existing data base to select the usable data from a LANDSAT analysis. The software package allows manipulation of grid cell data plus the flexibility to allow the user to include FORTRAN statements for special functions. Using this combination of capabilities the user can classify a LANDSAT image and then selectivity merge the results with other data that may exist for the study area.

Nordstrand, E. A.↗
NASA NTRS1983

Use of the VAS for analysis of a prethunderstorm environment

The information content of the VAS radiances can be converted to meteorological parameters useful for analyzing a severe weather environment. The method by which the VAS variances are converted to vertical profiles of temperature, dewpoints, and equivalent potential temperature involves a basic regression technique using the most local radiosonde data available for establishing a correlation matrix. The results indicate that mesoscale features apparent within images of the radiances can be converted to usable temperature and moisture fields using regression when surface temperature and dewpoint observations are included within the total data base. In addition, results indicate that surface data are very important for better defining lower tropospheric structure that the VAS radiances alone cannot properly resolve. Analyses of these retrievals distinctly show mesoscale structure in the temperature and moisture fields derived with VAS radiances collected every 3 hours, and 0000 GMT. The retrievals capture the moisture structure. More important, convective instability is clearly detected immediately before the onset of convection. The results indicate that the VAS is capable of providing valuable mesoscale information suitable for analyzing a preconvective environment that is generally clear.

Uccellini, L. W.↗
NASA NTRS1982

Part 1: Silicon ingot casting. Heat Exchanger Method (HEM)

Directional solidification by the Heat Exchanger Method (HEM) is a viable approach for directional solidification of silicon ingots used for terrestrial solar cell applications. Some of the significant advances made during this phase of the program were: ingot size, 34 cm x 34 cm x 17 cm - 45 kg, usable material yield - 90%, solar cell efficiency averaged over the whole ingot - 85% of control CZ (35 kg ingot), very uniform resistivity over the boule, and cycle time for 36 kg ingots - 56 hours. Some of the problems encountered were growth rate decrease with increased ingot height, silicon carbide precipitates, and high dislocation density in HEM material. The silicon carbide is attributed to backstreaming of oil vapors from the vacuum pump; the high dislocation density is associated with the thermal history of the boule.

Source record↗
NASA NTRS1982

Ohio's Abandoned Mine Lands Reclamation Program: a Study of Data Collection and Evaluation Techniques

The planning process for a statewide reclamation plan of Ohio abandoned minelands in response to the Federal Surface Mining Control and Reclamation Act of 1977 included: (1) the development of a screening and ranking methodology; (2) the establishment of a statewide review of major watersheds affected by mining; (3) the development of an immediate action process; and (4) a prototypical study of a priority watershed demonstrating the data collection, analysis, display and evaluation to be used for the remaining state watersheds. Historical methods for satisfying map information analysis and evaluation, as well as current methodologies being used were discussed. Various computer mapping and analysis programs were examined for their usability in evaluating the priority reclamation sites. Hand methods were chosen over automated procedures; intuitive evaluation was the primary reason.

Sperry, S. L.↗
NASA NTRS1983

Propagation effects handbook for satellite systems design. A summary of propagation impairments on 10 to 100 GHz satellite links with techniques for system design

This Propagation Handbook provides satellite system engineers with a concise summary of the major propagation effects experienced on Earth-space paths in the 10 to 100 GHz frequency range. The dominant effect, attenuation due to rain, is dealt with in some detail, in terms of both experimental data from measurements made in the U.S. and Canada, and the mathematical and conceptual models devised to explain the data. In order to make the Handbook readily usable to many engineers, it has been arranged in two parts. Chapters 2-5 comprise the descriptive part. They deal in some detail with rain systems, rain and attenuation models, depolarization and experimental data. Chapters 6 and 7 make up the design part of the Handbook and may be used almost independently of the earlier chapters. In Chapter 6, the design techniques recommended for predicting propagation effects in Earth-space communications systems are presented. Chapter 7 addresses the questions of where in the system design process the effects of propagation should be considered, and what precautions should be taken when applying the propagation results.

Ippolito, L. J.↗
NASA NTRS1983

High temperature glass thermal control structure and coating

A high temperature stable and solar radiation stable thermal control coating is described which is useful either as such, applied directly to a member to be protected, or applied as a coating on a re-usable surface insulation (RSI). It has a base coat layer and an overlay glass layer. The base coat layer has a high emittance, and the overlay layer is formed from discrete, but sintered together glass particles to give the overlay layer a high scattering coefficient. The resulting two-layer space and thermal control coating has an absorptivity-to-emissivity ratio of less than or equal to 0.4 at room temperature, with an emittance of 0.8 at 1200 F. It is capable of exposure to either solar radiation or temperatures as high as 2000 F without significant degradation. When used as a coating on a silica substrate to give an RSI structure, the coatings of this invention show significantly less reduction in emittance after long term convective heating and less residual strain than prior art coatings for RSI structures.

Stewart, D. A.↗
NASA NTRS1983

Development of a distributed-parameter mathematical model for simulation of cryogenic wind tunnels

A one-dimensional distributed-parameter dynamic model of a cryogenic wind tunnel was developed which accounts for internal and external heat transfer, viscous momentum losses, and slotted-test-section dynamics. Boundary conditions imposed by liquid-nitrogen injection, gas venting, and the tunnel fan were included. A time-dependent numerical solution to the resultant set of partial differential equations was obtained on a CDC CYBER 203 vector-processing digital computer at a usable computational rate. Preliminary computational studies were performed by using parameters of the Langley 0.3-Meter Transonic Cryogenic Tunnel. Studies were performed by using parameters from the National Transonic Facility (NTF). The NTF wind-tunnel model was used in the design of control loops for Mach number, total temperature, and total pressure and for determining interactions between the control loops. It was employed in the application of optimal linear-regulator theory and eigenvalue-placement techniques to develop Mach number control laws.

Tripp, J. S.↗
NASA NTRS1983

Propulsion and fluid management - Station keeping will eat energy on a new scale

An attempt is made to identify technologies that could be brought to a state of minimal development risk in the near term, yet offer the potential for evolutionary growth consistent with future space station propulsion requirements. Prospective auxiliary propulsion propellants will be usable by other systems, thereby offering resupply benefits and a benign rather than corrosive or toxic handling environment. NASA programs are currently underway to develop the storage and supply methods for cryogenic liquids in orbit. The recovery of unused propellants from the Space Shuttle Orbiter and External Tank are being evaluated in order to define Shuttle modifications and performance penalties. Fluid management subsystem requirements and characteristics cannot, however, be fully defined until a firm mission scenario has been established and other space station subsystems are more clearly defined.

Petrash, D. A.↗
NASA NTRS1982

Refractive field correctors for the Starlab ultraviolet telescope

Field correctors for a one-meter, f/15 cassegrainian telescope were designed as part of a NASA-funded study of an astronomical obervatory on board of the Space Shuttle. By means of a Gasgoigne corrector and a biconcave field flattener, astigmatism and field curvature are corrected in a 0.6 deg field. Applicable wavelength ranges are limited by chromatic aberrations. The upper wavelength is selected to match a photocathode response limit. The lower wavelength limit is defined by a filter. Examples of usable wavelength ranges are: 210 nm - 1100 nm (multialkali photocathode, fused-silica corrector elements), 177 nm - 320 nm (cesium telluride photocathode, calcium fluoride correctors); and possibly 134 nm - 190 nm (cesium iodide photocathode, lithium fluoride correctors). Residual rms lateral color is smaller than 0.02 arc sec, and axial color is smaller than 0.25 arc sec (blur diameter at the ends of the wavelength range). The correctors introduce a small amount of coma. This is compensated by adjustment of the conic constants of the telescope mirrors.

Bottema, M.↗
NASA NTRS1983

Thermoelectric energy conversion with solid electrolytes

The alkali metal thermoelectric converter (AMTEC) is a device for the direct conversion of heat to electrical energy. The sodium ion conductor beta-double prime-alumina is used to form a high-temperature regenerative concentration cell for elemental sodium. An AMTEC of mature design should have an efficiency of 20 to 40 percent, a power density of 0.5 kilowatt per kilogram or more, no moving parts, low maintenance requirements, high durability, and efficiency independent of size. It should be usable with high-temperature combustion, nuclear, or solar heat sources. Experiments have demonstrated the feasibility of the AMTEC and confirmed the theoretical analysis of the device. A wide range of applications from aerospace power to utility power plants appears possible.

Cole, T.↗