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  • Other Sources  (199)
  • ELECTRONICS AND ELECTRICAL ENGINEERING  (199)
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  • 1987  (199)
  • 1
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    TWT efficiency improvement by a low-cost technique for deposition of carbon on MDC electrodes (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A simple method of improving the TWT and multistage depressed collector (MDC) efficiency has been demonstrated. The efficiency improvement was produced by the application of a thin layer of carbon to the copper electrodes of the MDC by means of a rapid low-cost technique involving the pyrolysis of hydrocarbon oil in electric arc discharges. Experimental results with a representative TWT and MDC showed an 11 percent improvement in both the TWT and MDC efficiencies as compared to those of the same TWT and MDC with machined copper electrode surfaces. An extended test with a 550-W CW TWT indicated good durability of the carbon-coated electrode surfaces.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Electron Devices (ISSN 0018-9383); ED-34; 490-493
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  • 2
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    Recent trends in parts SEU susceptibility from heavy ions (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The authors collected a set of heavy-ion single event upset (SEU) test data since their last publication in December, 1985. Trends in SEU susceptibility for state-of-the-art parts are presented.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Nuclear Science (ISSN 0018-9499); NS-34; 1332-133
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  • 3
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    Bit-error-rate testing of high-power 30-GHz traveling-wave tubes for ground-terminal applications (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Tests were conducted at NASA Lewis to measure the bit-error-rate performance of two 30-GHz 200-W coupled-cavity traveling-wave tubes (TWTs). The transmission effects of each TWT on a band-limited 220-Mbit/s SMSK signal were investigated. The tests relied on the use of a recently developed digital simulation and evaluation system constructed at Lewis as part of the 30/20-GHz technology development program. This paper describes the approach taken to test the 30-GHz tubes and discusses the test data. A description of the bit-error-rate measurement system and the adaptations needed to facilitate TWT testing are also presented.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Electron Devices (ISSN 0018-9383); ED-34; 2625-263
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  • 4
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    All NbN tunnel junction fabrication (1987)
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    Publication Date: 2011-08-19
    Description: The development of SIS tunnel junctions based on NbN for mixer applications in the submillimeter range is reported. The unique technological challenges inherent in the development of all refractory-compound superconductor-based tunnel junctions are highlighted. Current deposition and fabrication techniques are discussed, and the current status of all-NbN tunnel junctions is reported.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: International Journal of Infrared and Millimeter Waves (ISSN 0195-9271); 8; 1243-124
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  • 5
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    Remote gate capacitance-voltage studies for noninvasive surface characterization (1987)
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    Publication Date: 2011-08-19
    Description: A measurement technique has been developed which allows noncontact capacitance-voltage measurements to be made using a gate electrode located remote from the semiconductor surface under study. With gate electrodes about 0.5 mm in diameter and gate to semiconductor separations of about 1500 A, it was possible to generate data entirely comparable to that obtained with integrated MIS structures but with the advantage that there was access directly to the free-semiconductor surface. This technique was applied to bulk single-crystal Si and InP samples.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Physics Letters (ISSN 0003-6951); 51; 987-989
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  • 6
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    Surface plasmon dispersion analysis in the metal-oxide-metal tunnel diode (1987)
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    Publication Date: 2011-08-19
    Description: A detailed model of surface plasmon dispersion in the metal-oxide-metal tunnel diode is presented in order to clarify the spectral emission from this diode. The model predicts the location of the spectral peaks and the emission between the peaks by considering the effects of retardation on the surface plasmon. A nonradiative mode is found to play a major role in the transition from the visible to UV peaks in the diode spectra.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Journal of Applied Physics (ISSN 0021-8979); 62; 1313-131
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  • 7
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    Preliminary results on CuInSe2/ZnSe solar cells using reactively sputter-deposited ZnSe (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In this paper preliminary results on CuInSe2/ZnSe thin film heterojunction photovoltaic devices are presented. High-conductivity ZnSe films were reactively sutter-deposited onto CuInSe2 films and overcoated with ZnO to reduce the sheet resistance. The highest short-circuit current density, as determined from a spectral response weighted for air mass 1.5 global insolation, was 37.4 mA/sq cm. The highest pen-circuit voltage observed was 430 mV.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Solar Cells (ISSN 0379-6787); 21; 225-232
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  • 8
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    Spectral-domain analysis of single and coupled cylindrical striplines (1987)
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    Publication Date: 2011-08-19
    Description: A spectral-domain technique for finding the characteristic impedances of a single cylindrical stripline and a coupled pair of cylindrical striplines is presented. Assuming a charge distribution on the strip, the variational expression for the line capacitance for single cylindrical stripline is derived. Good agreement with published results is obtained. The cylindrical coupled strip and microstrip lines are also analyzed and a comparison with their planar counterparts is made.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Microwave Theory and Techniques (ISSN 0018-9480); MTT-35; 672-675
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  • 9
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    Resistive synaptic interconnects for electronic neural networks (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The use of the alpha-Ge(1-x):Al(x) and alpha-Ge(1-x):Cu(x) alloys and Pt/Al2O3 cermet thin films as resistive interconnects for binary synaptic memory arrays is evaluated. The fabrication of the 10-20 microns long, 10 microns wide, and 0.1 micron thick interconnects from the alloys and cermet is described. The current-voltage and switching characteristics of the as-deposited films and the patterned test structure are studied. The resistivity, uniformity, stability, and compatibility of the interconnects are examined. It is observed that alpha-Ge(1-x):Cu(x) alloys have a wide resistivity range and low temperature coefficients of resistance; however, their long-term stability is limited due to their low crystallization temperature. It is detected that the alpha-Ge(1-x):Al(x) alloys have higher crystallization temperatures and their resistivity is not greatly affected by large changes in metal content. The Pt/Al2O3 samples display excellent stability, easy fabrication, and control of resistivity with metal content.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Journal of Vacuum Science and Technology A (ISSN 0734-2101); 5; 1407-141
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  • 10
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    1987 Annual Conference on Nuclear and Space Radiation Effects, Snowmass Village, CO, July 28-31, 1987, Proceedings (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Various papers on nuclear and space radiation effects are presented. The general topics addressed include: basic mechanisms of radiation effects, single-event phenomena, temperature and field effects, modeling and characterization of radiation effects, IC radiation effects and hardening, and EMP/SGEMP/IEMP phenomena. Also considered are: dosimetry/energy-dependent effects, sensors in and for radiation environments, spacecraft charging and space radiation effects, radiation effects and devices, radiation effects on isolation technologies, and hardness assurance and testing techniques.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: (ISSN 0018-9499)
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  • 11
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    Propagation delay measurements from a timing sampler intended for use in space (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A 3-micron CMOS timing sampler is described which is a test circuit designed into the Jet Propulsion Labs' CRRES chip to be flown on the Combined Release and Radiation Effects Satellite (CRRES). The timing sampler consists of 64 inverter-pair stages with sampling latches and decoder circuitry. The sampler is used to measure inverter-pair propagation delays, which are nominally 2.5 ns, with a resolution of 100 ps. A simple model was developed to explain the radiation-induced inverter-pair delay shifts in terms of radiation-induced MOSFET threshold-voltage shifts and effective modal capacitances. The magnitude of the shift in pair delay with radiation was estimated at the point where the n-MOSFET threshold voltage became zero. For a 0.7-V-threshold shift, the pair delay increased from its preradiation value by 360 ps for a rising step input and decreased by 190 ps for a falling step input.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Nuclear Science (ISSN 0018-9499); NS-34; 1470-147
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  • 12
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    Single-event upset (SEU) in a DRAM with on-chip error correction (1987)
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    Publication Date: 2011-08-19
    Description: Results are given of SEU measurements on 256K dynamic RAMs with on-chip error correction. They are claimed to be the first ever reported. A (12/8) Hamming error-correcting code was incorporated in the layout. Physical separation of the bits in each code word was used to guard against multiple bits being disrupted in any given word. Significant reduction in observed errors is reported.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Nuclear Science (ISSN 0018-9499); NS-34; 1310-131
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  • 13
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    Experimental evidence for a new single-event upset (SEU) mode in a CMOS SRAM obtained from model verification (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Modeling of SEU has been done in a CMOS static RAM containing 1-micron-channel-length transistors fabricated from a p-well epilayer process using both circuit-simulation and numerical-simulation techniques. The modeling results have been experimentally verified with the aid of heavy-ion beams obtained from a three-stage tandem van de Graaff accelerator. Experimental evidence for a novel SEU mode in an ON n-channel device is presented.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Nuclear Science (ISSN 0018-9499); NS-34; 1292-129
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  • 14
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    Microwave performance of an optically controlled AlGaAs/GaAs high electron mobility transistor and GaAs MESFET (1987)
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    Publication Date: 2011-08-19
    Description: Direct current and also the microwave characteristics of optically illuminated AlGaAs/GaAs HEMT are experimentally measured for the first time and compared with that of GaAs MESFET. The results showed that the average increase in the gain is 2.89 dB under 1.7 mW optical intensity at 0.83 microns. Further, the effect of illumination on S-parameters is more pronounced when the devices are biased close to pinch off. Novel applications of optically illuminated HEMT as a variable gain amplifier, high speed high frequency photodetector, and mixer are demonstrated.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Microwave Theory and Techniques (ISSN 0018-9480); MTT-35; 1444-145
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  • 15
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    Photon detection with cooled avalanche photodiodes (1987)
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    Publication Date: 2011-08-19
    Description: Commercial avalanche photodiodes have been operated as single-photon detectors at an optimum operating temperature and bias voltage. These detectors were found to be 1.5-3 times more sensitive than presently available photomultiplier tubes (PMTs). Both single-photon detection probability and detector noise increase with bias voltage; detection probabilities greater than twice that of a PMT were obtained with detector noise levels below 100 counts per second. Higher probabilities were measured at higher noise levels. The sources of noise and their dependence on temperature and bias voltage are discussed.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Physics Letters (ISSN 0003-6951); 51; 1493
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  • 16
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    Optical response at 10.6 microns in tungsten silicide Schottky barrier diodes (1987)
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    Publication Date: 2011-08-19
    Description: Optical response to radiation at a wavelength of 10.6 microns in tungsten silicide-silicon Schottky barrier diodes has been observed. Incident photons excite electrons by means of junction plasmon assisted inelastic electron tunneling. At 78 K, a peak in the second derivative of current versus junction bias voltage was observed at a voltage corresponding to the energy of photons having a wavelength of 10.6 microns. This peak increased with increasing incident laser power, saturating at the highest laser powers investigated.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Journal of Applied Physics (ISSN 0021-8979); 62; 3848-385
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  • 17
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    New flange correction formula applied to interfacial resistance measurements of ohmic contacts to GaAs (1987)
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    Publication Date: 2011-08-19
    Description: A quasi-two-dimensional analytical model is developed to account for vertical and horizontal current flow in and adjacent to a square ohmic contact between a metal and a thin semiconducting strip which is wider than the contact. The model includes side taps to the contact area for voltage probing and relates the 'apparent' interfacial resistivity to the (true) interfacial resistivity, the sheet resistance of the semiconducting layer, the contact size, and the width of the 'flange' around the contact. This relation is checked against numerical simulations. With the help of the model, interfacial resistivities of ohmic contacts to GaAs were extracted and found independent of contact size in the range of 1.5-10 microns.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Electron Device Letters (ISSN 0741-3106); EDL-8; 202-204
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  • 18
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    Implementation of optical interconnections for VLSI (1987)
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    Publication Date: 2011-08-19
    Description: This paper reports on the progress in implementing optical interconnections for VLSI. Four areas are covered: (1) the holographic optical element (HOE), (2) the laser sources, (3) the detectors and associated circuits forming an optically addressed gate, and (4) interconnection experiments in which five gates are actuated from one source. A laser scanner system with a resolution of 12 x 20 microns has been utilized to generate the HOEs. Diffraction efficiency of the HOE and diffracted spot size have been measured. Stock lasers have been modified with a high-frequency package for interconnect experiments, and buried heterostructure fabrication techniques have been pursued. Measurements have been made on the fabricated photodetectors to determine dark current, responsivity, and response time. The optical gates and the overall chip have been driven successfully with an input light beam, as well as with the optical signal interconnected through the one to five holograms.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Electron Devices (ISSN 0018-9383); ED-34; 706-714
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  • 19
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    Response of a metal-oxide-semiconductor field-effect transistor to a cosmic-ray ion track (1987)
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    Publication Date: 2011-08-19
    Description: A cosmic-ray ion track passing perpendicularly through the oxide layer of an enhancement-mode metal-oxide-semiconductor field-effect transistor (MOSFET) forms a conducting path, the resistance of which is proportional to the stopping power of the cosmic ion and independent of the cross-sectional area of the ion track. The voltage across the oxide capacitance may drop below the threshold voltage if the gate bias is sufficiently low or if the external resistance in the gate-source circuit is sufficiently high. The first of a pair of MOSFETs forming a flip-flop circuit may thus be turned off, and the second transitor may turn on, providing it has a sufficiently short delay time, thereby completing a single-event upset.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Journal of Applied Physics (ISSN 0021-8979); 61; 2374-238
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  • 20
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    Binary synaptic connections based on memory switching in a-Si:H for artificial neural networks (1987)
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    Publication Date: 2011-08-19
    Description: A scheme for nonvolatile associative electronic memory storage with high information storage density is proposed which is based on neural network models and which uses a matrix of two-terminal passive interconnections (synapses). It is noted that the massive parallelism in the architecture would require the ON state of a synaptic connection to be unusually weak (highly resistive). Memory switching using a-Si:H along with ballast resistors patterned from amorphous Ge-metal alloys is investigated for a binary programmable read only memory matrix. The fabrication of a 1600 synapse test array of uniform connection strengths and a-Si:H switching elements is discussed.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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  • 21
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    Quantum efficiencies of imaging detectors with alkali halide photocathodes. I - Microchannel plates with separate and integral CsI photocathodes (1987)
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    Publication Date: 2011-08-19
    Description: Measurements and comparisons have been made of the quantum efficiencies of microchannel plate (MCP) detectors in the far-UV (below 2000-A) wavelength range using CsI photocathodes (a) deposited on the front surfaces of microchannel plates and (b) deposited on solid substrates as opaque photocathodes with the resulting photoelectrons input to microchannel plates. The efficiences were measured in both pulse-counting and photodiode modes of operation. Typical efficiencies are about 15 percent at 1216 A for a CsI-coated MCP compared with 65 percent for an opaque CsI photocathode MCP detector. Special processing has yielded an efficiency as high as 20 percent for a CsI-coated MCP. This may possibly be further improved by optimization of the tilt angle of the MCP channels relative to the front face of the MCP and incident radiation. However, at present there still remains a factor of at least 3 quantum efficiency advantage in the separate opaque CsI photocathode configuration.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Optics (ISSN 0003-6935); 26; 2925-293
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  • 22
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    A further analysis for the minimum-variance deconvolution filter performance (1987)
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    Publication Date: 2011-08-19
    Description: Chi and Mendel (1984) analyzed the performance of minimum-variance deconvolution (MVD). In this correspondence, a further analysis of the performance of the MVD filter is presented. It is shown that the MVD filter performs like an inverse filter and a whitening filter as SNR goes to infinity, and like a matched filter as SNR goes to zero. The estimation error of the MVD filter is colored noise, but it becomes white when SNR goes to zero. This analysis also conects the error power-spectral density of the MVD filter with the spectrum of the causal-prediction error filter.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Acoustics, Speech, and Signal Processing (ISSN 0096-3518); ASSP-35; 888
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  • 23
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    Power and charge dissipation from an electrodynamic tether (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The Plasma Motor-Generator project utilizes the influence of the geomagnetic field on a conductive tether attached to a LEO spacecraft to provide a reversible conversion of orbital energy into electrical energy. The behavior of the current into the ionospheric plasma under the influence of the geomagnetic field is of significant experimental and theoretical interest. Theoretical calculations are reviewed which start from Maxwell's equations and treat the ionospheric plasma as a linear dielectric medium. These calculations show a charge emitting tether moving in a magnetic field will generate electromagnetic waves in the plasma which carry the charge in the direction of the magnetic field. The ratio of the tether's speed to the ion cyclotron frequency which is about 25 m for a LEO is a characteristic length for the phenomena. Whereas for the dimensions of the contact plasma much larger than this value the waves are the conventional Alfven waves, when the dimensions are comparable or smaller, diffraction effects occur similar to those associated with Fresnel diffraction in optics. The power required to excite these waves for a given tether current is used to estimate the impedance associated with this mode of charge dissipation.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA. Johnson Space Center, NASA(ASEE Summer Faculty Fellowship Program, 1987, Volume 1; 20 p
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  • 24
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    Nickel hydrogen low Earth orbit test program update and status (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The current status of nickel-hydrogen (NiH2) testing ongong at NWSC, Crane In, and The Aerospace Corporation, El Segundo, Ca are described. The objective of this testing is to develop a database for NiH2 battery use in Low Earth Orbit (LEO) and support applications in Medium Altitude Orbit (MAO). Individual pressure vessel-type cells are being tested. A minimum of 200 cells (3.5 in diameter and 4.5 in diameter) are included in the test, from four U.S. vendors. As of this date (Nov. 18, 1986) approximately 60 cells have completed preliminary testing (acceptance, characterization, and environmental testing) and have gone into life cycling.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 167-188
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  • 25
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    Battery development and testing at ESA (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The principal activities of the Energy Storage Section of the Space Research and Technology Center (ESTEC) of the European Space Agency are presented. Nickel-hydrogen and fuel cell systems development are reported. The European Space Battery Test Center (ESBTC) facilities are briefly described along with the current test programs and results obtained.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 141-165
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  • 26
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    Chemical analysis of charged Li/SO(sub)2 cells (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The initial focus of the program was to confirm that charging can indeed result in explosions and constitute a significant safety problem. Results of this initial effort clearly demonstrated that cells do indeed explode on charge and that charging does indeed constitute a real and severe safety problem. The results of the effort to identify the chemical reactions involved in and responsible for the observed behavior are described.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 121-137
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  • 27
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    Fault tree safety analysis of a large Li/SOCl(sub)2 spacecraft battery (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The results of the safety fault tree analysis on the eight module, 576 F cell Li/SOCl2 battery on the spacecraft and in the integration and test environment prior to launch on the ground are presented. The analysis showed that with the right combination of blocking diodes, electrical fuses, thermal fuses, thermal switches, cell balance, cell vents, and battery module vents the probability of a single cell or a 72 cell module exploding can be reduced to .000001, essentially the probability due to explosion for unexplained reasons.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 93-119
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  • 28
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    The MOLICEL(R) rechargeable lithium system: Multicell battery aspects (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: MOLICEL rechargeable lithium cells were cycled in batteries using series, parallel, and series/parallel connections. The individual cell voltages and branch currents were measured to understand the cell interactions. The observations were interpreted in terms of the inherent characteristics of the Li/MoS2 system and in terms of a singular cell failure mode. The results confirm that correctly configured multicell batteries using MOLICELs have performance characteristics comparable to those of single cells.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 73-91
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  • 29
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    The 250AH/90A active lithium-thionyl chloride cell for Centaur-G application (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: A high rate active Li/SOCl2 cell was designed for use in a 28 volt, 250 amp-hour space battery system. The lithium battery is being considered as a replacement of its heavier silver-zinc counterpart on board the Centaur-G booster rocket which is used to launch payloads from the Space Shuttle cargo bay into deep-space. Basically a feasibility study, this development effort is demonstrating the ability of the lithium cell to deliver up to 90 amps safely at power densities of approximately 25 watts per pound. Test data on 4 prototype units is showing an energy density of 85 watt-hours per pound and 9.0 watt-hours/cu in. The cells tested typically delivered 280 to 300 amp-hours under ambient temperature test conditions using alternating continuous loads of 90, 55, and 20 amperes throughout life. Data from four cells tested are presented to demonstrate the capability of Li/SOCl2 technology for a C/3 discharge rate in active and hermetic cell units.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 61-72
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    A comparison of VLSI architecture of finite field multipliers using dual, normal or standard basis (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Three different finite field multipliers are presented: (1) a dual basis multiplier due to Berlekamp; (2) a Massy-Omura normal basis multiplier; and (3) the Scott-Tavares-Peppard standard basis multiplier. These algorithms are chosen because each has its own distinct features which apply most suitably in different areas. Finally, they are implemented on silicon chips with nitride metal oxide semiconductor technology so that the multiplier most desirable for very large scale integration implementations can readily be ascertained.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 63-75
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  • 31
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    Computer simulation of thermal modeling of primary lithium cells (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The objective was to gain a better understanding of the safety problem of primary Li-SOCl2 and Li-SO2 cells by carrying out detailed thermal modeling work. In particular, the transient heat generation rates during moderate and extermely high discharge rate tests of Li-SOCl2 cells were predicted and compared with those from the electrochemical heating. The difference between the two may be attributed to the lithium corrosion and other chemical reactions. The present program was also tested for charging of Li-SO2. In addition, the present methodology should be applicable to other primary cylindrical cells as well as rechargeable battery analyses with minor modifications.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 21-60
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  • 32
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    Power supply conditioning circuit (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A power supply conditioning circuit that can reduce Periodic and Random Deviations (PARD) on the output voltages of dc power supplies to -150 dBV from dc to several KHz with no measurable periodic deviations is described. The PARD for a typical commercial low noise power supply is -74 dBV for frequencies above 20 Hz and is often much worse at frequencies below 20 Hz. The power supply conditioning circuit described here relies on the large differences in the dynamic impedances of a constant current diode and a zener diode to establish a dc voltage with low PARD. Power supplies with low PARD are especially important in circuitry involving ultrastable frequencies for the Deep Space Network.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 1-7
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  • 33
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    Determination of diffusion coefficients in polypyrrole thin films using a current pulse relaxation method (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The current pulse E sub oc relaxation method and its application to the determination of diffusion coefficients in electrochemically synthesized polypyrrole thin films is described. Diffusion coefficients for such films in Et4NBF4 and MeCN are determined for a series of submicron film thicknesses. Measurement of the double-layer capacitance, C sub dl, and the resistance, R sub u, of polypyrrole thin films as a function of potential obtained with the galvanostatic pulse method is reported. Measurements of the electrolyte concentration in reduced polypyrrole films are also presented to aid in the interpretation of the data.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: New Secondary Batteries Utilizing Electronically Conductive Polymer Cathodes; 50 p
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  • 34
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    A mathematical model for predicting cyclic voltammograms of electronically conductive polypyrrole (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Polypyrrole is an attractive polymer for use as a high-energy-density secondary battery because of its potential as an inexpensive, lightweight, and noncorrosive electrode material. A mathematical model to simulate cyclic voltammograms for polypyrrole is presented. The model is for a conductive porous electrode film on a rotating disk electrode (RDE) and is used to predict the spatial and time dependence of concentration, overpotential, and stored charge profiles within a polypyrrole film. The model includes both faradic and capacitance charge components in the total current density expression.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: New Secondary Batteries Utilizing Electronically Conductive Polymer Cathodes; 28 p
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  • 35
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    AC impedance analysis of polypyrrole thin films (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The AC impedance spectra of thin polypyrrole films were obtained at open circuit potentials from -0.4 to 0.4 V vs SCE. Two limiting cases are discussed for which simplified equivalent circuits are applicable. At very positive potentials, the predominantly nonfaradaic AC impedance of polypyrrole is very similar to that observed previously for finite porous metallic films. Modeling of the data with the appropriate equivalent circuit permits effective pore diameter and pore number densities of the oxidized film to be estimated. At potentials from -0.4 to -0.3 V, the polypyrrole film is essentially nonelectronically conductive and diffusion of polymer oxidized sites with their associated counterions can be assumed to be linear from the film/substrate electrode interface. The equivalent circuit for the polypyrrole film at these potentials is that previously described for metal oxide, lithium intercalation thin films. Using this model, counterion diffusion coefficients are determined for both semi-infinite and finite diffusion domains. In addition, the limiting low frequency resistance and capacitance of the polypyrrole thin fims was determined and compared to that obtained previously for thicker films of the polymer. The origin of the observed potential dependence of these low frequency circuit components is discussed.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: New Secondary Batteries Utilizing Electronically Conductive Polymer Cathodes; 54 p
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  • 36
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    An interactive wire-wrap board layout program (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An interactive computer-graphics-based tool for specifying the placement of electronic parts on a wire-wrap circuit board is presented. Input is a data file (currently produced by a commercial logic design system) which describes the parts used and their interconnections. Output includes printed reports describing the parts and wire paths, parts counts, placement lists, board drawing, and a tape to send to the wire-wrap vendor. The program should reduce the engineer's layout time by a factor of 3 to 5 as compared to manual methods.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 101-107
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  • 37
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    A VLSI single chip (255,223) Reed-Solomon encoder with interleaver (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A single-chip implementation of a Reed-Solomon encoder with interleaving capability is described. The code used was adapted by the CCSDS (Consulative Committee on Space Data Systems). It forms the outer code of the NASA standard concatenated coding system which includes a convolutional inner code of rate 1/2 and constraint length 7. The architecture, leading to this single VLSI chip design, makes use of a bit-serial finite field multiplication algorithm due to E.R. Berlekamp.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 41-47
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  • 38
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    Interchange of electronic design through VHDL and EIS (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The need for both robust and unambiguous electronic designs is a direct requirement of the astonishing growth in design and manufacturing capability during recent years. In order to manage the plethora of designs, and have the design data both interchangeable and interoperable, the Very High Speed Integrated Circuits (VHSIC) program is developing two major standards for the electronic design community. The VHSIC Hardware Description Language (VHDL) is designed to be the lingua franca for transmission of design data between designers and their environments. The Engineering Information System (EIS) is designed to ease the integration of data betweeen diverse design automation systems. This paper describes the rationale for the necessity for these two standards and how they provide a synergistic expressive capability across the macrocosm of design environments.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA. Lyndon B. Johnson Space Center, Houston, Texas, First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 119-124
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  • 39
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    High-temperature electronics (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: In recent years, there was a growing need for electronics capable of sustained high-temperature operation for aerospace propulsion system instrumentation, control and condition monitoring, and integrated sensors. The desired operating temperature in some applications exceeds 600 C, which is well beyond the capability of currently available semiconductor devices. Silicon carbide displays a number of properties which make it very attractive as a semiconductor material, one of which is the ability to retain its electronic integrity at temperatures well above 600 C. An IR-100 award was presented to NASA Lewis in 1983 for developing a chemical vapor deposition process to grow single crystals of this material on standard silicon wafers. Silicon carbide devices were demonstrated above 400 C, but much work remains in the areas of crystal growth, characterization, and device fabrication before the full potential of silicon carbide can be realized. The presentation will conclude with current and future high-temperature electronics program plans. Although the development of silicon carbide falls into the category of high-risk research, the future looks promising, and the potential payoffs are tremendous.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Aeropropulsion '87. Session 4: Instrumentation and Controls Research; 10 p
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  • 40
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    Mathematical model for the dc-ac inverter for the Space Shuttle (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The reader is informed of what was done for the mathematical modeling of the dc-ac inverter for the Space Shuttle. The mathematical modeling of the dc-ac inverter is an essential element in the modeling of the electrical power distribution system of the Space Shuttle. The electrical power distribution system which is present on the Space Shuttle is made up to 3 strings each having a fuel cell which provides dc to those systems which require dc, and the inverters which convert the dc to ac for those elements which require ac. The inverters are units which are 2 wire structures for the main dc inputs and 2 wire structures for the ac output. When 3 are connected together a 4 wire wye connection results on the ac side. The method of modeling is performed by using a Least Squares curve fitting method. A computer program is presented for implementation of the model along with graphs and tables to demonstrate the accuracy of the model.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA. Johnson Space Center, NASA(ASEE Summer Faculty Fellowship Program, 1987, Volume 1; 20 p
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  • 41
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    Test summary for advanced H2 cycle NI-CD cell (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: To improve operational tolerances and mass, the H2 gas recombination design provisions of the Ni-H2 system were incorporated into the sealed Ni-Cd system. Produced is a cell design capable of operating on the H2 cycle versus the normal O2 cycle. Three test cells have now completed approximately 4,330 LEO (90 minute) cycles at 20 percent depth of discharge (DOD). Performance remains stable although one cell exhibited a temporary pressure anomaly.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 343-350
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  • 42
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    Survey of current correlators and applications (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: With this summary an attempt is made to contact as many users as possible so as to provide summary data on correlation systems, both in use and as planned. Data on currently available very large scale integration (VLSI) chips and complete systems are included. Also, several planned correlator systems are described and summarized in tabular form. Finally, a description is given of the work being done in the Communications Systems Research Section on VLSI correlator chips and complete correlator systems.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 54-62
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  • 43
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    A millimeter wave Josephson mixer employing a high-T(c) GdBaCuO point contact (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A Josephson effect heterodyne mixer for the millimeter wave band was investigated employing high-T(c) GdBaCuO point contacts. Mixer performance was in qualitative agreement with theory. A mixing response was observed up to 55 K, the highest operating temperature achieved for such a device to date. The voltage separation of RF-induced steps gave a value of h/2e = 2.08 x 10 to the -15th V s, which is in excellent agreement with the value expected for Cooper pairs. In addition, the temperature dependence of the I(0)R product was found to agree with Bardeen-Cooper-Schrieffer theory in the weak coupling limit.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Journal of Applied Physics (ISSN 0021-8979); 62; 4923-492
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  • 44
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    Submillimeter backward wave oscillators (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A NASA program for the development of backward wave oscillators (BWOs) for the 500-2000 GHz frequency range is discussed. The BWO operation is based on a periodic etched slow wave structure which supports the induced traveling electromagnetic wave. The present submillimeter wave BWOs will employ a variation of the folded wave guide, the interdigital line. The use of a noncompressed electron beam results in less thermal loading of the circuit, smaller magnetic focusing fields, and higher current density of the circuit interaction region. The diamond etching procedure is described. Aluminum will be used for the metallization of the diamonds.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: International Journal of Infrared and Millimeter Waves (ISSN 0195-9271); 8; 1257-126
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  • 45
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    Submillimeter-wave antennas on thin membranes (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Submillimeter-wave antennas have been fabricated on 1-micron thick silicon-oxynitride membranes. This approach results in better patterns than previous lens-coupled antennas, and eliminates the dielectric loss associated with the substrate lens. Measurements on a wideband log-periodic antenna at 700 GHz, 370 GHz and 167 GHz show no sidelobes and 3-dB beamwidths between 40 and 60 deg. A linear imaging array has similar patterns at 700 GHz. Possible applications for membrane antennas include wideband superconducting tunnel-junction receivers for radio astronomy and imaging arrays for radiometry and plasma diagnostics.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: International Journal of Infrared and Millimeter Waves (ISSN 0195-9271); 8; 1249-125
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  • 46
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    Flash technology for charge-coupled-device imaging in the ultraviolet (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The introduction of the flash gate has made possible the fabrication of backside-illuminated CCDs with high sensitivity and stability throughout a wide range of ultraviolet and visible wavelengths (100 to 5000 A). It had been determined previously that the characteristics of the oxide layer beneath the gate are critical to the ultimate achievable CCD performance. However, by creating an improved oxide layer in conjunction with the flash gate, it is now possible to consistently produce CCDs with near-ideal UV performance. In this paper recent results and related background theory that optimize the flash gate specifically for application in the UV are presented.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Optical Engineering (ISSN 0091-3286); 26; 852-863
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  • 47
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    Radiation characteristics of microstrip arrays with parasitic elements (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Detailed experimental results on microstrip antennas consisting of one center-fed patch and several identical parasitic patches are presented. The effects of the number of elements and interelement spacing are studied for two configurations: a linear array and a five-element array. It is shown that placing identical parasitic elements adjacent to a fed patch permits broadside radiation patterns with significant enhancement in gain to be obtained without any degradation of the pattern characteristics.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Electronics Letters (ISSN 0013-5194); 23; 835-837
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  • 48
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    Characteristics of inhomogeneous coupled cylindrical striplines (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Using conformal transformation, closed-form expressions for the even and odd mode impedances of inhomogeneous coupled cylindrical striplines are presented. It is shown that the analysis can be extended for the calculation of characteristics of coupled cylindrical microstrip lines. The analysis can also be extended to reveal the effects of warping due to environmental changes on an otherwise planar structure.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Electronics Letters (ISSN 0013-5194); 23; 821
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  • 49
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    New simple feed network for an array module of four microstrip elements (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A simple microstripline feed network for an array module comprising four microstrip elements is described. The advantages and disadvantages of the network are discussed as well as a theoretical explanation for the radiation characteristics of array modules using the network.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Electronics Letters (ISSN 0013-5194); 23; 436
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  • 50
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    Front surface passivation of silicon solar cells with antireflection coating (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is demonstrated that the deposition and postdeposition sintering of an antireflection (AR) coating in hydrogen acts to passivate silicon solar cells. Cells with and without an SiO2 passivating layer, coated with a TiO(x)/Al2O3 AR coating, showed comparable enhancements in short-wavelength spectral response and in open-circuit voltage Voc after sintering at 400 C for 5 min in a hydrogen ambient. The improvement in Voc of cells without SiO2 is attributed to front-surface passivation by the AR coating during processing.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Journal of Applied Physics (ISSN 0021-8979); 61; 3077-307
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  • 51
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    Microwave performance of InAlAs/InGaAs/InP MODFET's (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Modulation-doped InAlAs/InGaAs/InP structures were grown by molecular beam epitaxy and fabricated into FETs with excellent RF gain performance. The intrinsic transconductance was about 400 mS/mm at 300 K. Current gain cutoff frequencies of up to 26.5 GHz were obtained in 1-micron gate devices. Extremely small S12 and large S21 led to a very large F(max) of 62 GHz. These results represent the best reported figures for 1-micron devices in this material system, and slightly better than those obtained in recently developed pseudomorphic modulation-doped field effect transistors.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Electron Device Letters (ISSN 0741-3106); EDL-8; 24-26
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  • 52
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    Evaluation of high-voltage, high-power, solid-state remote power controllers for amps (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Electrical Power Branch at Marshall Space Flight Center has a Power System Development Facility where various power circuit breadboards are tested and evaluated. This project relates to the evaluation of a particular remote power controller (RPC) energizing high power loads. The Facility equipment permits the thorough testing and evaluation of high-voltage, high-power solid-state remote power controllers. The purpose is to evaluate a Type E, 30 Ampere, 200 V dc remote power controller. Three phases of the RPC evaluation are presented. The RPC is evaluated within a low-voltage, low-power circuit to check its operational capability. The RPC is then evaluated while performing switch/circuit breaker functions within a 200 V dc, 30 Ampere power circuit. The final effort of the project relates to the recommended procedures for installing these RPC's into the existing Autonomously Managed Power System (AMPS) breadboard/test facility at MSFC.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA. Marshall Space Flight Center, Research Reports: 1987 NASA(ASEE Summer Faculty Fellowship Program; 24 p
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  • 53
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    Statistically determined nickel cadmium performance relationships (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A statistical analysis was performed on sealed nickel cadmium cell manufacturing data and cell matching data. The cells subjected to the analysis were 30 Ah sealed Ni/Cd cells, made by General Electric. A total of 213 data parameters was investigated, including such information as plate thickness, amount of electrolyte added, weight of active material, positive and negative capacity, and charge-discharge behavior. Statistical analyses were made to determine possible correlations between test events. The data show many departures from normal distribution. Product consistency from one lot to another is an important attribute for aerospace applications. It is clear from these examples that there are some significant differences between lots. Statistical analyses are seen to be an excellent way to spot those differences. Also, it is now proven beyond doubt that battery testing is one of the leading causes of statistics.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 335-342
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  • 54
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    Real time charge efficiency monitoring for nickel electrodes in NICD and NIH2 cells (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The charge efficiency of nickel-cadmium and nickel-hydrogen battery cells is critical in spacecraft applications for determining the amount of time required for a battery to reach a full state of charge. As the nickel-cadmium or nickel-hydrogen batteries approach about 90 percent state of charge, the charge efficiency begins to drop towards zero, making estimation of the total amount of stored charge uncertain. Charge efficiency estimates are typically based on prior history of available capacity following standardized conditions for charge and discharge. These methods work well as long as performance does not change significantly. A relatively simple method for determining charge efficiencies during real time operation for these battery cells would be a tremendous advantage. Such a method was explored and appears to be quite well suited for application to nickel-cadmium and nickel-hydrogen battery cells. The charge efficiency is monitored in real time, using only voltage measurements as inputs. With further evaluation such a method may provide a means to better manage charge control of batteries, particularly in systems where a high degree of autonomy or system intelligence is required.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 311-333
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  • 55
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    Flight experience of solar mesosphere explorer's power system over high temperatures ranges (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The performance of the power system on the Solar Mesosphere Explorer (SME) satellite for the life of the mission and the techniques used to ensure power system health are summarized. Early in the mission high cell imbalances in one of the batteries resulted in a loading scheme which attempted to minimize the cell imbalances without causing an undervoltage condition. A short term model of the power system allowed planners to predict depth of discharge using the latest available data. Due to expected orbital shifts the solar arrays experience extended periods of no eclipse. This has required special conditioning schemes to keep the batteries healthy when the eclipses return. Analysis of the SME data indicates long term health of the SME power system as long as the conditioning scheme is continued.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 301-308
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  • 56
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    Qualification testing of General Electric 50 Ah nickel-cadmium cells with Pellon 2536 separator and passivated positive plates (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Forty-two 50 Ah nickel-cadmium cells were delivered to the Goddard Space Flight Center (GSFC) by General Electric (GE) in February, 1985 for the purpose of evaluating and qualifying a nonwoven nylon separator material, Pellon 2536, and the GE positive plate nickel attack control gas passivation process. Testing began May, 1985 at the Naval Weapons Support Center (NWSC) in Crane, Indiana with GSFC standard initial evaluation tests. Life cycling in both Low Earth Orbit (LEO) and Geosynchronous Orbit (GEO) began in July, 1985 with approximately 6500 LEO cycles and three GEO eclipse seasons completed. After early problems in maintaining test pack temperature control, all packs are performing well but are exhibiting higher than normal charge voltage characteristics.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The 1986 Goddard Space Flight Center Battery Workshop; p 277-300
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  • 57
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    Effects of long term storage on aerospace nickel cadmium cell performance (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Evaluation of the long term effects on aerospace nickel cadmium cells is described. A number of 6Ah and 12Ah capacity cells which were stored in shorted condition for 9 to 11 years at the Goddard Space Flight Center were selected for the study. Of the three tests which were initiated (initial and final destruction analyses of the test cells, electrical characterization tests, and life cycling tests) only the electrical characterization tests are completed; the other tests are scheduled to be completed by February 1987. The preliminary electrial performance data from the life cycling test and chemical composition data from the destructive testing indicate no anomalous behavior.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The 1986 Goddard Space Flight Center Battery Workshop; p 257-276
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    Earth Radiation Budget Satellite (ERBS) orbiting profiles and Ni-Cd use (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Earth Radiation Budget Satellite (ERBS) is one of the more recently launched satellites of the Goddard Space Flight Center. The flight data of the two 50 Ah NASA standard batteries that are being flown on the ERBS are presented. Trend characteristics of the batteries were collected over a period of two years. The parameters that were trended are: the battery end-of-discharge voltage, time in peak power track, and time in constant current mode. All were plotted versus mission elapsed time. The slopes exhibited by the trended parameters indicate no adverse trends that would signify any appreciable degradation in the batteries.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The 1986 Goddard Space Flight Center Battery Workshop; p 247-255
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    BRASILSAT A2: Ground and in-orbit anomalies (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A description of the anomalies encountered during ground preparation for launch and in-orbit operation of Brasilsat A2 batteries is given. Processes used during recovery of these batteries and the improvement on main parameters are discussed, covering many cycles of reconditionings and behavior during September/86 eclipse charge/discharge cycles.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 225-229
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    International Ultraviolet Explorer (IUE) spacecraft battery performance update (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: January 26, 1987 marks the ninth inflight aniversary of the IUE spacecraft, launched into an eccentric synchronous orbit. The orbital path has subjected the spacecraft to 18 solar eclipse seasons since launch. Nine years of inflight operations culminate a major milestone for battery support to a spacecraft, which is well in excess of the initial 3 year design life. A brief outline of events, power system characteristics, and papers presented a previous battery workshops are provided. The IUE battery cell performance is excellent with the exception of the third electrode anomaly and temperature delta between batteries. Data indicates that battery depth-of-discharge (DOD) may be more critical to extend battery life than small operational temperature deltas between batteries. It is predicted that several additional years of battery life may be obtained by a reduction in operational battery DOD.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The 1986 Goddard Space Flight Center Battery Workshop; p 231-246
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    Grace DAKASEP alkaline battery separator (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Grace DAKASEP separator was originally developed as a wicking layer for nickel-zinc alkaline batteries. The DAKASEP is a filled non-woven separator which is flexible and heat sealable. Through modification of formulation and processing variables, products with a variety of properties can be produced. Variations of DAKASEP were tested in Ni-H2, Ni-Zn, Ni-Cd, and primary alkaline batteries with good results. The properties of DAKASEP which are optimized for Hg-Zn primary batteries are shown in tabular form. This separator has high tensile strength, 12 micron average pore size, relatively low porosity at 46-48 percent, and consequently moderately high resistivity. Versions were produced with greater than 70 percent porosity and resistivities in 33 wt percent KOH as low as 3 ohm cm. Performance data for Hg-Zn E-1 size cells containing DAKASEP with the properties shown in tabular form, are more reproducible than data obtained with a competitive polypropylene non-woven separator. In addition, utilization of active material is in general considerably improved.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 215-222
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    Failure analysis of a 3.5 inch, 50 ampere-hour nickel-hydrogen cell (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The 3.5 inch, 50 ampere-hour nickel-hydrogen cell was on a Low Earth Orbit (LEO) test regime and was being cycled at 10 C and 60 percent depth of discharge. At cycle number 511 the Automatic Control and Data Acquisition System (ACDAS) terminated the test when the end of discharge voltage dropped below the 1.00 volt cutoff. Upon removal of the stack assembly from the pressure vessel, portions of the zircar separator were found to be completely missing. Upon further examination portions of both the positive and negative plates were found to be missing from its substrate and several gas screens were damaged due to excessive heat which caused fusing. The postulated cause of failure is free electrolyte in the cell which caused oxygen channelization resulting in localized recombination which degraded the stack components.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 209-213
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    Advances in nickel hydrogen technology at Yardney Battery Division (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The current major activites in nickel hydrogen technology being addressed at Yardney Battery Division are outlined. Five basic topics are covered: an update on life cycle testing of ManTech 50 AH NiH2 cells in the LEO regime; an overview of the Air Force/industry briefing; nickel electrode process upgrading; 4.5 inch cell development; and bipolar NiH2 battery development.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA Goddard Space Flight Center, Greenbelt, Md. The 1986 Goddard Space Flight Center Battery Workshop; p 189-208
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    X-band phase calibration generator coupler (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A new type of phase calibration generator (PCG) coupler was developed for the Deep Space Network (DSN) X-band antennas that can be located directly behind the feedhorn. The advantage of this is that the calibration includes more of the system. The disadvantage is that the overmoded waveguide at this location must be coupled in a mode-selective manner. Low-power and high-power PCG couplers have been successfully produced, and the RF test results from a PCG coupler are given.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 89-93
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    Diffusion length measurements in bulk and epitaxially grown 3-5 semiconductors using charge collection microscopy (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Diffusion lengths and surface recombination velocities were measured in GaAs diodes and InP finished solar cells. The basic techniques used was charge collection microscopy also known as electron beam induced current (EBIC). The normalized currents and distances from the pn junction were read directly from the calibrated curves obtained while using the line scan mode in an SEM. These values were then equated to integral and infinite series expressions resulting from the solution of the diffusion equation with both extended generation and point generation functions. This expands previous work by examining both thin and thick samples. The surface recombination velocity was either treated as an unknown in a system of two equations, or measured directly using low e(-) beam accelerating voltages. These techniques give accurate results by accounting for the effects of surface recombination and the finite size of the generation volume.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-100128 , E-3677 , NAS 1.15:100128
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    An experimental investigation of parasitic microstrip arrays (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The characteristics of a parasitic microstrip antenna array with a center-fed patch are experimentally investigated. The parasitic array is composed of identical parasitic patches which are symmetrically arranged and electromagnetically coupled to a center-fed patch. The shape and dimensions of the parasitic patches and their positions relative to the center-fed patch are parameters in the study. To show mutual coupling effects between radiating and nonradiating edges of adjacent patches, the impedance and radiation characteristics of a three-element parasitic array excited with (0.1) mode are examined, and compared to that of a single patch. Experimental data indicate that the presence of parasitic patches has significant effects upon the gain, resonant frequency, and impedance bandwidth of the array.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-100168 , E-3731 , NAS 1.15:100168
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    Computer control of a scanning electron microscope for digital image processing of thermal-wave images (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Using a recently developed technology called thermal-wave microscopy, NASA Lewis Research Center has developed a computer controlled submicron thermal-wave microscope for the purpose of investigating III-V compound semiconductor devices and materials. This paper describes the system's design and configuration and discusses the hardware and software capabilities. Knowledge of the Concurrent 3200 series computers is needed for a complete understanding of the material presented. However, concepts and procedures are of general interest.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-100157 , E-3719 , NAS 1.15:100157
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    Processing circuit with asymmetry corrector and convolutional encoder for digital data (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A processing circuit is provided for correcting for input parameter variations, such as data and clock signal symmetry, phase offset and jitter, noise and signal amplitude, in incoming data signals. An asymmetry corrector circuit performs the correcting function and furnishes the corrected data signals to a convolutional encoder circuit. The corrector circuit further forms a regenerated clock signal from clock pulses in the incoming data signals and another clock signal at a multiple of the incoming clock signal. These clock signals are furnished to the encoder circuit so that encoded data may be furnished to a modulator at a high data rate for transmission.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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    On the synchronizability and detectability of random PPM sequences (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The problem of synchronization and detection of random pulse-position-modulation (PPM) sequences is investigated under the assumption of perfect slot synchronization. Maximum likelihood PPM symbol synchronization and receiver algorithms are derived that make decisions based both on soft as well as hard data; these algorithms are seen to be easily implementable. Bounds were derived on the symbol error probability as well as the probability of false synchronization that indicate the existence of a rather severe performance floor, which can easily be the limiting factor in the overall system performance. The performance floor is inherent in the PPM format and random data and becomes more serious as the PPM alphabet size Q is increased. A way to eliminate the performance floor is suggested by inserting special PPM symbols in the random data stream.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-CR-181125 , NAS 1.26:181125
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    Analytical and experimental performance of a dual-mode traveling wave tube and multistage depressed collector (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A computational procedure for the design of traveling-wave-tube(TWT)/refocuser/multistage depressed collector (MDC) systems was used to design a short, permanent-magnet refocusing system and a highly efficient MDC for a medium-power, dual-mode, 4.8- to 9.6-GHz TWT. The computations were carried out with advanced, multidimensional computer programs which model the electron beam and follow the trajectories of representative charges from the radiofrequency (RF) input of the TWT, through the slow-wave structure and refocusing section, to their points of impact in the depressed collector. Secondary emission losses in the MDC were treated semiquantitatively by injecting representative secondary-electron-emission current into the MDA analysis at the point of impact of each primary beam. A comparison of computed and measured TWT and MDC performance showed very good agreement. The electrodes of the MDC were fabricated from a particluar form of isptropic graphite that was selected for its low secondary electron yield, ease of machinability, and vacuum properties.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TP-2752 , E-3470 , NAS 1.60:2752
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    Reciprocating linear motor (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A reciprocating linear motor is formed with a pair of ring-shaped permanent magnets having opposite radial polarizations, held axially apart by a nonmagnetic yoke, which serves as an axially displaceable armature assembly. A pair of annularly wound coils having axial lengths which differ from the axial lengths of the permanent magnets are serially coupled together in mutual opposition and positioned with an outer cylindrical core in axial symmetry about the armature assembly. One embodiment includes a second pair of annularly wound coils serially coupled together in mutual opposition and an inner cylindrical core positioned in axial symmetry inside the armature radially opposite to the first pair of coils. Application of a potential difference across a serial connection of the two pairs of coils creates a current flow perpendicular to the magnetic field created by the armature magnets, thereby causing limited linear displacement of the magnets relative to the coils.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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    A study of Schwarz converters for nuclear powered spacecraft (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: High power space systems which use low dc voltage, high current sources such as thermoelectric generators, will most likely require high voltage conversion for transmission purposes. This study considers the use of the Schwarz resonant converter for use as the basic building block to accomplish this low-to-high voltage conversion for either a dc or an ac spacecraft bus. The Schwarz converter has the important assets of both inherent fault tolerance and resonant operation; parallel operation in modular form is possible. A regulated dc spacecraft bus requires only a single stage converter while a constant frequency ac bus requires a cascaded Schwarz converter configuration. If the power system requires constant output power from the dc generator, then a second converter is required to route unneeded power to a ballast load.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89911 , E-3588 , NAS 1.15:89911 , AIAA PAPER 87-9314
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    Automatic detection of electric power troubles (AI application) (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The design goals for the Automatic Detection of Electric Power Troubles (ADEPT) were to enhance Fault Diagnosis Techniques in a very efficient way. ADEPT system was designed in two modes of operation: (1) Real time fault isolation, and (2) a local simulator which simulates the models theoretically.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-86593 , NAS 1.15:86593
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    Programmable electronic synthesized capacitance (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A predetermined and variable synthesized capacitance which may be incorporated into the resonant portion of an electronic oscillator for the purpose of tuning the oscillator comprises a programmable operational amplifier circuit. The operational amplifier circuit has its output connected to its inverting input, in a follower configuration, by a network which is low impedance at the operational frequency of the circuit. The output of the operational amplifier is also connected to the noninverting input by a capacitor. The noninverting input appears as a synthesized capacitance which may be varied with a variation in gain-bandwidth product of the operational amplifier circuit. The gain-bandwidth product may, in turn, be varied with a variation in input set current with a digital to analog converter whose output is varied with a command word. The output impedance of the circuit may also be varied by the output set current. This circuit may provide very small ranges in oscillator frequency with relatively large control voltages unaffected by noise.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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    Automated measurement of the bit-error rate as a function of signal-to-noise ratio for microwave communications systems (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The performance of microwave systems and components for digital data transmission can be characterized by a plot of the bit-error rate as a function of the signal to noise ratio (or E sub b/E sub o). Methods for the efficient automated measurement of bit-error rates and signal-to-noise ratios, developed at NASA Lewis Research Center, are described. Noise measurement considerations and time requirements for measurement accuracy, as well as computer control and data processing methods, are discussed.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89898 , E-3585 , NAS 1.15:89898
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    Full-scale engine demonstration of an advanced sensor failure detection, isolation and accommodation algorithm: Preliminary results (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The objective of the advanced detection, isolation, and accommodation (ADIA) program is to improve the overall demonstrated reliability of digital electronic control systems for turbine engines. For this purpose, algorithms were developed which detect, isolate, and accommodate sensor failures using analytical redundancy. Preliminary results of a full scale engine demonstration of the ADIA algorithm are presented. Minimum detectable levels of sensor failures for an F100 turbofan engine control system are determined and compared to those obtained during a previous evaluation of this algorithm using a real-time hybrid computer simulation of the engine.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89880 , E-3561 , NAS 1.15:89880 , AIAA PAPER 87-2259
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    Radiation and temperature effects in gallium arsenide, indium phosphide and silicon solar cells (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The effects of radiation on performance are determined for both n(+)p and p(+)n GaAs and InP cells and for silicon n(+)p cells. It is found that the radiation resistance of InP is greater than that of both GaAs and Si under 1 MeV electron irradiation. For silicon, the observed decreased radiation resistance with decreased resistivity is attributed to the presence of a radiation induced boron-oxygen defect. Comparison of radiation damage in both p(+)n and n(+)p GaAs cells yields a decreased radiation resistance for the n(+)p cell attributable to increased series resistance, decreased shunt resistance, and relatively greater losses in the cell's p-region. For InP, the n(+)p configuration is found to have greater radiation resistance than the p(+)n cell. The increased loss in this latter cell is attributed to losses in the cell's emitter region. Temperature dependency results are interpreted using a theoretical relation for dVoc/cT which predicts that increased Voc should results in decreased numerical values for dPm/dT. The predicted correlation is observed for GaAs but not for InP a result which is attributed to variations in cell processing.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89870 , E-3546 , NAS 1.15:89870
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    Traveling-wave-tube efficiency improvement by a low-cost technique for deposition of carbon on multistage depressed collector (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A simple method of improving the traveling-wave-tube (TWT) and multistage depressed collector (MDC) efficiency has been demonstrated. The efficiency improvement was produced by the application of a thin layer of carbon to the copper electrodes of the MDC by means of a rapid, low-cost technique involving the pyrolysis of hydrocarbon oil in electric arc discharges. Experimental results with a representative TWT and MDC showed an 11 percent improvement in both the TWT and MDC efficiencies as compared to those of the same TWT and MDC efficiencies with bare copper electrode surfaces. An extended test with a 500-W, continuous wave (CW) TWT and small-sized MDC indicated good stability of the carbon coated electrode surfaces after a relatively small initial degradation in TWT overall and apparent MDC efficiencies.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TP-2719 , E-3416 , NAS 1.60:2719
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    Comparator with noise suppression (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: An apparatus for generating a single pulse the first time only that a noisy cyclic signal exceeds a reference level during a half-cycle is disclosed. For the positive half of a cycle of the noisy cyclic signal, a comparator and a multivibrator produce a fixed voltage output when the noisy cyclic signal first exceeds the reference level. A multivibrator stops the production of the fixed voltage output when the noisy cyclic signal next passes the zero voltage level in the negative direction. Consequently, a single pulse is generated indicating that the signal exceeded the reference level during that half-cycle. The comparator and multi-vibrator produce pulses whenever the noisy cyclic signal exceeds the reference level during the negative half-cycle.
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    Precision tunable resonant microwave cavity (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A tunable microwave cavity containing ionizable metallic vapor or gases and an apparatus for precisely positioning a microwave coupling tip in the cavity and for precisely adjusting at least one dimension of the cavity are disclosed. With this combined structure, resonance may be achieved with various types of ionizable gases. A coaxial probe extends into a microwave cavity through a tube. One end of the tube is retained in a spherical joint attached in the cavity wall. This allows the coaxial probe to be pivotally rotated. The coaxial probe is slideable within the tube thus allowing the probe to be extended toward or retracted from the center of the cavity.
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    Four quadrant control circuit for a brushless three-phase dc motor (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A control circuit is provided for a brushless three-phase dc motor which affords four quadrant control from a single command. The control circuit probes acceleration of the motor in both clockwise and counterclockwise directions and braking and generation in both clockwise and counterclockwise directions. In addition to turning on individual transistors of the transistor pairs connected to the phase windings of the motor for 120 deg periods while the other transistor of that pair is off, the control circuit also provides, in a future mode of operation, turning the two transistors of each pair on and off alternately at a phase modulation frequency during such a 120 deg period. A feedback signal is derived which is proportional to the motor current and which has a polarity consistent with the command signal, such that negative feedback results.
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    Low phase noise oscillator using two parallel connected amplifiers (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A high frequency oscillator is provided by connecting two amplifier circuits in parallel where each amplifier circuit provides the other amplifier circuit with the conditions necessary for oscillation. The inherent noise present in both amplifier circuits causes the quiescent current, and in turn, the generated frequency, to change. The changes in quiescent current cause the transconductance and the load impedance of each amplifier circuit to vary, and this in turn results in opposing changes in the input susceptance of each amplifier circuit. Because the changes in input susceptance oppose each other, the changes in quiescent current also oppose each other. The net result is that frequency stability is enhanced.
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    Description of a magnetic bearing test fixture (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A description of a microcomputer controlled magnetic bearing test fixture is presented. Parameters which are controlled are magnetic bearing current and gaps. Parameters which are measured are magnetic bearing gaps, magnetic flux in the bearing gaps, and bearing forces. The test fixture is configured for bearing elements similar to those used in a laboratory test model Annular Momentum Control Device (AMCD).
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89081 , NAS 1.15:89081
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    Analysis of 12 AH aerospace nickel-cadmium cells from the design variable program (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Design Variable Program of NASA/GSFC provided a systematic approach to evaluate the performance of 12 Ampere-Hour Nickel-Cadmium cells of different designs. Design Variables tested in this program included teflonated negative plates, silver treated negative plates, lightly loaded negative plates, positive plates with no cadmium treatment, plate design of 1968 utilizing old and new processing techniques and electrochemically impregnated positive plates. These cells were life cycled in a Low-Earth Orbit (LEO) regime for 3 to 4 years. Representative cells taken from the Design Variable Program were examined via chemical, electrochemical and surface analyses. The results indicate the following: (1) positive swelling and carbonate content in the electrolyte increase as a function of number of cycles; (2) electrolyte distribution follows a general order NEG greater than POS greater than SEP; (3) control and No PQ groups outperformed the rest of the groups; and (4) the polyproylene group exhibited heavy cadmium migration and poor performance.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-87774 , NAS 1.15:87774 , REPT-86BO186
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    Resistojet control and power for high frequency ac buses (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Resistojets are operational on many geosynchronous communication satellites which all use dc power buses. Multipropellant resistojets were selected for the Initial Operating Capability (IOC) Space Station which will supply 208 V, 20 kHz power. This paper discusses resistojet heater temperature controllers and passive power regulation methods for ac power systems. A simple passive power regulation method suitable for use with regulated sinusoidal or square wave power was designed and tested using the Space Station multipropellant resistojet. The breadboard delivered 20 kHz power to the resistojet heater. Cold start surge current limiting, a power efficiency of 95 percent, and power regulation of better than 2 percent were demonstrated with a two component, 500 W breadboard power controller having a mass of 0.6 kg.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89860 , E-3527 , NAS 1.15:89860 , AIAA PAPER 87-0994
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    Referencing in fiber optic sensing systems (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Different techniques to account for losses induced by the environment on signals in intensity modulation fiber optic sensing systems are described and analyzed.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89822 , E-3468 , NAS 1.15:89822
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  • 87
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    Design, fabrication and performance of small, graphite electrode, multistage depressed collectors with 200-W, CW, 8- to 18-GHz traveling-wave tubes (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Small multistage depressed collectors (MDC's) which used pyrolytic graphite, ion-beam-textured pyrolytic graphite, and isotropic graphite electrodes were designed, fabricated, and evaluated in conjuntion with 200-W, continuous wave (CW), 8- to 18-GHz traveling-wave tubes (TWT's). The design, construction, and performance of the MDC's are described. The bakeout performance of the collectors, in terms of gas evolution, was indistinguishable from that of typical production tubes with copper collectors. However, preliminary results indicate that some additional radiofrequency (RF) and dc beam processing time (and/or longer or higher temperature bakeouts) may be needed beyond that of typical copper electrode collectors. This is particularly true for pyrolytic graphite electrodes and for TWT's without appendage ion pumps. Extended testing indicated good long-term stability of the textured pyrolytic graphite and isotropic graphite electrode surfaces. The isotropic graphite in particular showed considerable promise as an MDC electrode material because of its high purity, low cost, simple construction, potential for very compact overall size, and relatively low secondary electron emission yield characteristics in the as-machined state. However, considerably more testing experience is required before definitive conclusions on its suitability for electronic countermeasure systems and space TWT's can be made.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TP-2693 , E-3099 , NAS 1.60:2693
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  • 88
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    System architecture of MMIC-based large aperture arrays for space application (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The persistent trend to use millimeter-wave frequencies for satellite communications presents the challenge to design large-aperture phased arrays for space applications. These arrays, which comprise 100 to 10,000 elements, are now possible due to the advent of lightwave technology and the availability of monolithic microwave integrated circuits. In this paper, system aspects of optically controlled array design are studied. In particular, two architectures for a 40 GHz array are outlined, and the main system-related issues are examined: power budget, synchronization in frequency and phase, and stochastic effects.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89840 , E-3482 , NAS 1.15:89840
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  • 89
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    In-circuit fault injector user's guide (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A fault injector system, called an in-circuit injector, was designed and developed to facilitate fault injection experiments performed at NASA-Langley's Avionics Integration Research Lab (AIRLAB). The in-circuit fault injector (ICFI) allows fault injections to be performed on electronic systems without special test features, e.g., sockets. The system supports stuck-at-zero, stuck-at-one, and transient fault models. The ICFI system is interfaced to a VAX-11/750 minicomputer. An interface program has been developed in the VAX. The computer code required to access the interface program is presented. Also presented is the connection procedure to be followed to connect the ICFI system to a circuit under test and the ICFI front panel controls which allow manual control of fault injections.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-100478 , NAS 1.15:100478
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  • 90
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    Nonlinear filter design (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A technique for identifying nonlinear systems was introduced, beginning with a single input-single output system. Assuming the system is initially at rest, the first kernel (first convolution integral in the continuous case or first convolution sum in the discrete case) was calculated. A controllable and observable linear realization was then obtained in a particular canonical form. The actual nonlinear system was probed with an appropriate input (or inputs) and the output (or outputs) determined. For the linear system, the input was computed that produces the same output. In the difference between the inputs to the nonlinear and linear systems, basic information was found about the nonlinear system. There is an interesting class of nonlinear systems for which this type of identification scheme should prove to be accurate.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-CR-181239 , NAS 1.26:181239
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  • 91
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    Thermal evaluation method for Klystron RF power (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The feasibility of adding instrumentation to the cooling system of a microwave transmitter for use as a calorimetric power measurement calibration is examined. It considers the accuracy of the basic measurements as well as heat sources and losses not measured. Experimental results are presented in support of the theory.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 91-95
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  • 92
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    Microwave performance of an optically controlled AlGaAs/GaAs high electron mobility transistor and GaAs MESFET (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Direct current and also the microwave characteristics of optically illuminated AlGaAs/GaAs HEMT are experimentally measured for the first time and compared with that of GaAs MESFET. The results showed that the average increase in the gain is 2.89 dB under 1.7 nW/sq cm optical intensity at 0.83 microns. Further, the effect of illumination on S-parameters is more pronounced when the devices are biased close to pinch off. Novel applications of optically illuminated HEMT as a variable gain amplifier, high speed high frequency photo detector, and mixer are demonstrated.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-88980 , E-3333 , NAS 1.15:88980
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  • 93
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    Directional couplers for detecting the TE sub 11 and TE sub 12 circular waveguide modes (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The theoretical and experimental results for a pair of mode-selective directional couplers designed to detect the TE sub 11 and TE sub 12 modes in a multimode circular wavelength are described. A brief description of the design of the couplers is presented, followed by a comparison of their measured and calculated parameters. The couplers were used to measure the characteristics of a circular waveguide mode converter. The results of these measurements are described.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: The Telecommunications and Data Acquisition Report; p 11-16
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  • 94
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    Electro-expulsive separation system (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An electro-expulsive system has one or more overlapped conductors, each comprising a flexible ribbon conductor, which is folded back on itself. The conductors are embedded in an elastomeric material. Large current pulses are fed to the conductors from power storage units. As a result of the antiparallel currents, the opposed segments of a conductor are forcefully separated and the elastomeric material is distended. Voids in the elastomer aid the separation of the conductor segments. The distention is almost instantaneous when a current pulse reaches the conductor and the distention tends to remove any solid body on the surface of the elastomeric material.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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  • 95
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    Self-consistent inclusion of space-charge in the traveling wave tube (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: It is shown how the complete field of the electron beam may be incorporated into the transmission line model theory of the traveling wave tube (TWT). The fact that the longitudinal component of the field due to the bunched beam is not used when formulating the beam-to-circuit coupling equation is not well-known. The fundamental partial differential equation for the traveling wave field is developed and compared with the older (now standard) one. The equation can be solved numerically using the same algorithms, but now the coefficients can be updated continuously as the calculation proceeds down the tube. The coefficients in the older equations are primarily derived from preliminary measurements and some trial and error. The newer coefficients can be found by a recursive method, since each has a well defined physical interpretation and can be calculated once a reasonable first trial solution is postulated. The results of the new expression were compared with those of the older forms, as well as to a field theory model to show the ease in which a reasonable fit to the field prediction is obtained. A complete summary of the existing transmission line modeling of the TWT is given to explain the somewhat vague ideas and techniques in the general area of drifting carrier-traveling circuit wave interactions. The basic assumptions and inconsistencies of the existing theory and areas of confusion in the general literature are examined and hopefully cleared up.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89928 , E-3633 , NAS 1.15:89928
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  • 96
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    Synchronization trigger control system for flow visualization (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The use of cinematography or holographic interferometry for dynamic flow visualization in an internal combustion engine requires a control device that globally synchronizes camera and light source timing at a predefined shaft encoder angle. The device is capable of 0.35 deg resolution for rotational speeds of up to 73 240 rpm. This was achieved by implementing the shaft encoder signal addressed look-up table (LUT) and appropriate latches. The developed digital signal processing technique achieves 25 nsec of high speed triggering angle detection by using direct parallel bit comparison of the shaft encoder digital code with a simulated angle reference code, instead of using angle value comparison which involves more complicated computation steps. In order to establish synchronization to an AC reference signal whose magnitude is variant with the rotating speed, a dynamic peak followup synchronization technique has been devised. This method scrutinizes the reference signal and provides the right timing within 40 nsec. Two application examples are described.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89902 , E-3449 , SAE-PAPER-870450 , NAS 1.15:89902
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  • 97
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    Issues in space photovoltaic research and technology (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Key issues and opportunities in space photovoltaic research and technology are addressed relative to future NASA mission requirements and drivers. Examples are given of future space missions and/or operational capabilities that are on NASA's planning horizon presenting major tachnology challenges to the use of photovoltaic power generation in space. A brief description of the capabilities ascribed to the competing technologies of nuclear and solar thermal power systems are given. The performance goals that space photovoltaic power systems must meet to remain competitive are described.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-TM-89922 , E-3620 , NAS 1.15:89922
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  • 98
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    Space station power semiconductor package (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A package of high-power switching semiconductors for the space station have been designed and fabricated. The package includes a high-voltage (600 volts) high current (50 amps) NPN Fast Switching Power Transistor and a high-voltage (1200 volts), high-current (50 amps) Fast Recovery Diode. The package features an isolated collector for the transistors and an isolated anode for the diode. Beryllia is used as the isolation material resulting in a thermal resistance for both devices of .2 degrees per watt. Additional features include a hermetical seal for long life -- greater than 10 years in a space environment. Also, the package design resulted in a low electrical energy loss with the reduction of eddy currents, stray inductances, circuit inductance, and capacitance. The required package design and device parameters have been achieved. Test results for the transistor and diode utilizing the space station package is given.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-CR-180829 , NAS 1.26:180829
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  • 99
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    Electronic heterodyne moire deflectometry: A method for transient and three dimensional density fields measurements (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Effects of diffraction and nonlinear photographic emulsion characteristics on the performance of deferred electronic heterodyne moire deflectometry are investigated. The deferred deflectometry is used for measurements of nonsteady phase objects where it is difficult to complete the analysis of the field in real time. The sensitivity, accuracy and resolution of the system are calculated and it is shown that they are weakly affected by diffraction and by nonlinear recording. The feactures of the system are significantly improved compared with the conventional deferred intensity moire technique, and are comparable with the online heterodyne moire. The system was evaluated experimentally by deferred measurements of the refractive index gradients of a weak phase object consisting of a large KD*P crystal. This was done by photographing the phase object through a Ronchi grating and analyzing the tranparency with the electronic heterodyne readout system. The results are compared with the measurements performed on the same phase object with online heterodyne moire deflectometry and with heterodyne holographic interferometry methods. Some practical considerations for system improvement are discussed.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-CR-181134 , NAS 1.26:181134
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  • 100
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    Floating emitter solar cell (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A front surface contact floating emitter solar cell transistor is provided in a semiconductor body (n-type), in which floating emitter sections (p-type) are diffused or implanted in the front surface. Between the emitter sections, a further section is diffused or implanted in the front surface, but isolated from the floating emitter sections, for use either as a base contact to the n-type semiconductor body, in which case the section is doped n+, or as a collector for the adjacent emitter sections.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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