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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Fines in fluidized bed silane pyrolysis

Silicon deposition on silicon seed particles by silane pyrolysis in a fluidized-bed reactor is investigated as a low-cost, high-throughput method to produce high-purity polysilicon for solar-cell applications. Studies of fines, particles 0.1-10 microns diam, initiated from homogeneous decomposition in the reactor were conducted using 2 and 6-in-diam fluidized beds. The studies show functional dependences of fines elutriation on silane feed concentration, temperature, gas velocity, and bubble size. The observation that the fines elutriation is generally below 10 percent of the silicon-in-silane feed is attributed to scavenging by large particles in an environment of less free space for homogeneous nucleation. Preliminary results suggest that, with proper conditions and distributor design, high-silane-concentration (over 50 percent SiH4 in H2) feed may be used.

Hsu, G.↗
NASA NTRS1983

Sheet silicon cell/module technology

The cost involved in the performance of the standard operations for the manufacture of silicon wafers is insignificant in the case of space photovoltaics applications. It is, however, a decisive factor with respect to terrestrial applications of silicon photovoltaic devices. In 1975, a program was, therefore, begun to develop low cost silicon solar arrays for terrestrial applications. The goal was silicon-based photovoltaic (PV) modules ready for installation at a selling price of $0.50/watt (1975 dollars). Sheet and ribbon silicon growth held out the promise of reduced cost through continuous operation, high material throughput, high material utilization efficiency, and a product whose shape lent itself to the assembly of high packing density modules. Attention is given to ribbon growth technologies, sheet technology generic problems, and ribbon cell and module technology status. It is concluded that the potential for crystalline ribbon silicon appears to be better today than ever before.

Morrison, A. D.↗
NASA NTRS1986

Modular, Fast, Two-Dimensional Cyclic Convolver

Proposed high-throughput, real-time synthetic-aperture-radar (SAR) processor built using new, modular, two-dimensional cyclic convolver architecture based on polynomial factorization and designed for very-large-scale integrated (VLSI) circuitry. New architecture reduces cost, size, and power dissipation of SAR processor in comparison to high-speed array-processor approach. Processor also used for other image-and data-processing applications involving two-dimensional Fourier transforms.

Liu, K. Y.↗
NASA NTRS1984

Detailed Performance Calculations: Goddard Group, Appendix D

Two systems were described. The first used polarization to reduce scattered solar flux, the principal source of noise. The second used a narrowband detector and a different excitation wavelength. The results, which consider these systems, were presented emphasizing anticipated technology improvements because the analysis for each system required estimates of critical parameter even though each system would use existing technology. For the first, the information about the degree of polarization of the scattered solar flux was not measured but was estimated as 60 percent for viewing straight up with a solar zenith angle of 75 percent at sea level. The expected performance of this system therefore depends on the reliability of this estimate. For the second system, two estimates were required. First, the expected throughput of a Fabry-Perot interferometer operating at 309 nm, based on the performance exhibited by similar instruments working at other wavelengths, was estimated to be 3 percent. Second, the fluorescence efficiency of the proposed OH lines was estimated as 0.00004, since these quantities were not measured to date.

Source record↗
NASA NTRS1984

Atmospheric Modeling And Sensor Simulation (AMASS) study

The capabilities of the atmospheric modeling and sensor simulation (AMASS) system were studied in order to enhance them. This system is used in processing atmospheric measurements which are utilized in the evaluation of sensor performance, conducting design-concept simulation studies, and also in the modeling of the physical and dynamical nature of atmospheric processes. The study tasks proposed in order to both enhance the AMASS system utilization and to integrate the AMASS system with other existing equipment to facilitate the analysis of data for modeling and image processing are enumerated. The following array processors were evaluated for anticipated effectiveness and/or improvements in throughput by attachment of the device to the P-e: (1) Floating Point Systems AP-120B; (2) Floating Point Systems 5000; (3) CSP, Inc. MAP-400; (4) Analogic AP500; (5) Numerix MARS-432; and (6) Star Technologies, Inc. ST-100.

Parker, K. G.↗
NASA NTRS1985

Research of advanced techniques for X-ray detectors and telescopes with applications to rockets and the LAMAR facility

A program for the development of high throughput instrumentation for X-ray astronomy based upon focusing optics is being carried out by the Smithsonian Astrophysical Observatory. The instrumentation is applicable to investigations requiring large area focusing optics for direct imaging or dispersive spectroscopy. The long range goals of this program are the development of telescopes and gratings for future major X-ray astronomy facilities, including additions to the LAMAR OSS-2/SHEAL experiment after the initial flights. Tests of the devices and their more immediate utilization in scientific investigations can be carried out with SPARTAN payloads deployed and retrieved by the Space Shuttle. However, the present backlog of approved SPARTAN missions is longer than the three-year duration of the program described in this program. Laboratory studies and breadboarding of instrumentation are discussed.

Gorenstein, P.↗
NASA NTRS1984

A fast, programmable hardware architecture for the processing of spaceborne SAR data

The development of high-throughput SAR processors (HTSPs) for the spaceborne SARs being planned by NASA, ESA, DFVLR, NASDA, and the Canadian Radarsat Project is discussed. The basic parameters and data-processing requirements of the SARs are listed in tables, and the principal problems are identified as real-operations rates in excess of 2 x 10 to the 9th/sec, I/O rates in excess of 8 x 10 to the 6th samples/sec, and control computation loads (as for range cell migration correction) as high as 1.4 x 10 to the 6th instructions/sec. A number of possible HTSP architectures are reviewed; host/array-processor (H/AP) and distributed-control/data-path (DCDP) architectures are examined in detail and illustrated with block diagrams; and a cost/speed comparison of these two architectures is presented. The H/AP approach is found to be adequate and economical for speeds below 1/200 of real time, while DCDP is more cost-effective above 1/50 of real time.

Bennett, J. R.↗
NASA NTRS1984

The applications developmental data system

This paper describes a research and development system under development at NASA Goddard Space Flight Center (GSFC) for processing Landsat-4 Thematic Mapper (TM) data at high throughput rates. This system, called the Applications Developmental Data System (ADDS) is being developed with 2 objectives. First, during the initial year of Landsat-4 operations, ADDS provides an essential link in processing the TM images for image data quality assessment. The second objective is to demonstrate the ability to produce a radiometrically corrected TM image in 8 minutes and a geometrically correct image in 16 minutes. The processing rates currently achieved are presented.

Mocarsky, W. L.↗
NASA NTRS1984

Using Ada for a distributed, fault tolerant system

It is pointed out that advanced avionics applications increasingly require underlying machine architectures which are damage and fault tolerant, and which provide access to distributed sensors, effectors and high-throughput computational resources. The Advanced Information Processing System (AIPS), sponsored by NASA, is to provide an architecture which can meet the considered requirements. Ada was selected for implementing the AIPS system software. Advantages of Ada are related to its provisions for real-time programming, error detection, modularity and separate compilation, and standardization and portability. Chief drawbacks of this language are currently limited availability and maturity of language implementations, and limited experience in applying the language to real-time applications. The present investigation is concerned with current plans for employing Ada in the design of the software for AIPS. Attention is given to an overview of AIPS, AIPS software services, and representative design issues in each of four major software categories.

Dewolf, J. B.↗
NASA NTRS1985

Evaluation of an experimental system for spaceborne processing of multispectral image data

An experimental data processing system has been developed to demonstrate the feasibility of processing high speed, multispectral image data on board the spacecraft. The design incorporates real-time processing with adaptable operation in an expandable architecture. The experimental hardware is coupled to test support and computing equipment to provide a laboratory tool for evaluating and demonstrating each of the processing functions as well as the overall system operation. An evaluation of the high speed processor was conducted to ensure that the desired system throughput was achieved without sacrificing processing accuracy. A description of the system is presented along with the results of the test and evaluation activity.

Meredith, B. D.↗
NASA NTRS1984

Design and technology considerations for the far ultraviolet spectroscopic explorer (FUSE) telescope

An initial assessment of telescope designs satisfying the basic requirements derived for the FUSE mission is presented. A review of recent optical coating technology indicates that normal incidence telescope designs are viable only for wavelengths greater than about 600 A. It is noted that glancing incidence telescope designs, such as the Wolter Type II or thg Wolter-Schwarzschild, are the only designs with acceptable throughputs for the entire FUSE spectral range. Initial design trade studies have established the fundamental framework for the selection of an optimum Type II design satisfying the FUSE science and engineering requirements. It is also found that current optical fabrication technology, e.g., computer controlled polishing, can accommodate meter class glancing incidence components with figure errors commensurate with 1-2 arcsec imaging.

Davila, P. S. M.↗
NASA NTRS1984

Emitter formation in dendritic web silicon solar cells

The use of liquid dopants and liquid masks for p-n junction formation in dendritic web solar cells was investigated and found to be equivalent to the use of gaseous dopants and CVD SiO2 masks previously used. This results in a projected cost reduction of 0.02 1980$/Watt for a 25 MW/year production line, and makes possible junction formation processes having a higher throughput than more conventional processes. The effect of a low-energy (0.4 keV) hydrogen ion implant on dendritic web solar cells was also investigated. Such an implant was observed to improve Voc and Jsc substantially. Measurements of internal quantum efficiency suggest that it is the base of the cell, rather than the emitter, which benefits from the hydrogen implant. The diffusion length for electrons in the p-type base increased from 53 microns to 150 microns in one case, with dendritic web cell efficiency being boosted to 15.2 percent. The mechanism by which low-energy hydrogen ions can penetrate deeply into the silicon to effect the observed improvement is not known at this time.

Meier, D. L.↗
NASA NTRS1985

Application of Ritz vectors for dynamic analysis of large structures

The use of an orthogonal set of specially selected Ritz vectors is shown to be very effective in reducing the cost of dynamic analysis by modal superposition. Several mechanical structures are examined, and the Ritz vector approach is compared to the classical eigenvector approach on the basis of cost, accuracy and elapsed analysis (throughput) time. Mathematical proof of the completeness of orthogonal Ritz vectors is provided for the case of a positive definite mass matrix and a symmetric stiffness matrix.

Arnold, R. R.↗
NASA NTRS1985

The Broad Band X-ray telescope

The Broad-Band X-ray Telescope (BBXRT) has been designed to perform high sensitivity, moderate resolution spectrophotometry of X-ray sources in the 0.3-12 keV band from the Shuttle. It consists of a coaligned pair of high throughput conical X-ray imaging mirrors, with a cryogenically cooled multiple element Si(Li) spectrometer at the focus of each. On axis, BBXRT will have an effective area of 580 sq cm at 2 keV and 250 sq cm at 7 keV, and a spectral resolution of 110 eV at 2 keV and 150 eV at 7 keV. A 10,000-s observation with BBXRT will allow a determination of the continuum spectral shape for sources near the Einstein deep survey limit.

Petre, R.↗
NASA NTRS1985

The Factory of the Future

A brief history of aircraft production techniques is given. A flexible machining cell is then described. It is a computer controlled system capable of performing 4-axis machining part cleaning, dimensional inspection and materials handling functions in an unmanned environment. The cell was designed to: allow processing of similar and dissimilar parts in random order without disrupting production; allow serial (one-shipset-at-a-time) manufacturing; reduce work-in-process inventory; maximize machine utilization through remote set-up; maximize throughput and minimize labor.

Byman, J. E.↗
NASA NTRS1985

Thin film module development

The design of ARCO Solar, Inc.'s Genesis G100 photovoltaic module was driven by several criteria, including environmental stability (both electrical and mechanical), consumer aesthetics, low materials costs, and manufacturing ease. The module circuitry is designed as a 12 volt battery charger, using monolithic patterning techniques on a glass superstrate. This patterning and interconnect method proves amenable to high volume, low cost production throughput, and the use of glass serves the dual role of handling ease and availability. The mechanical design of the module centers on environmental stability. Packaging of the glass superstrate circuit must provide good resistance to thermal and humidity exposure along with hi-pot insulation and hailstone impact resistance. The options considered are given. Ethylene vinyl acetate (EVA) is chosen as the pottant material for its excellent weatherability.

Jester, T.↗
NASA NTRS1985

Ground processing of the McDonnell Douglas Payload Assist Module (PAM)

The payload assist module (PAM) ground processing operations which have evolved since they were started in 1982 are described. The objective of the changes was to reduce the prelaunch testing of the airborne support equipment to increase the throughput of PAM systems while not compromising the reliability of the system when functioned on-orbit. The changes that resulted from the initial cargo element ground processing, the on-orbit performance of the systems, plus the postflight refurbishment and recertification of the airborne support equipment resulted in significant reductions in labor expenditures and work shifts required to prepare a PAM system for flight.

Bryan, C. E.↗
NASA NTRS1984

Separator plugs for liquid helium

Work performed during Summer 1984 (from June to Sept. 30) in the area of porous media for use in low temperature applications is discussed. Recent applications are in the area of vapor - liquid phase separation, pumping based on the fountain effect and related subsystems. Areas of potential applications of the latter are outlined in supplementary work. Experimental data have been developed. The linear equations of the two-fluid model are inspected critically in the light of forced convection evidence reported recently. It is emphasized that the Darcy permeability is a unique throughput quantity in the porous media application areas whose use will permit meaningful comparisons of data not only in one lab but also within a group of labs doing porous plug studies.

Lee, J. M.↗