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  • Other Sources  (3,589)
  • ENERGY PRODUCTION AND CONVERSION  (2,380)
  • COMMUNICATIONS AND RADAR  (988)
  • Aerodynamics
  • Cell & Developmental Biology
  • General Chemistry
  • Limnology
  • 2020-2022  (2)
  • 1975-1979  (3,371)
  • 1945-1949  (142)
  • 1940-1944  (69)
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  • 1
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    Development of an Aeroservoelastic Model for Gust Load Alleviation of the NASA Common Research Model Wind Tunnel Experiment (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-23
    Description: As aircraft move to using composite materials as their primary structure they become lighter and more flexible as well. This presents some significant challenges in association with gust load alleviation. In this paper we develop an aeroservoelastic model for use in developing controllers that utilize distributed control surfaces for active gust load alleviation in a set of wind tunnel experiments. The model is based on an preexisting aeroelastic wing tunnel model and compares the baseline functionality to it. We also provide simple full state feedback simulations for the model.
    Keywords: Aerodynamics
    Type: AIAA 2020-0211 , ARC-E-DAA-TN76375 , AIAA Scitech 2020 Forum; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
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  • 2
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    Development of Unsteady Pressure-Sensitive Paint Application on NASA Space Launch System (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-17
    Description: The key measurement to acquire for understanding unsteady flow is surface pressure. Unsteady Pressure-Sensitive Paint (uPSP) is an emerging optical technique used in wind tunnel testing to measure fluctuating surface pressures. Recently, tests were conducted on NASAs Space Launch System in NASA Ames Research Centers Unitary Plan Wind Tunnel to determine the aeroacoustics environment and assist in developing the buffet forcing functions. Unsteady PSP data was collected during this test campaign. Steady state PSP data, infrared thermography, shadowgraph, accelerometer data, and dynamic pressure transducer data were also collected. In all 50 TB of data were collected during the three days of testing. During these three days of testing, a repeating transonic and supersonic alpha sweep condition was acquired. This paper presents these two wind tunnel conditions and examines how the temperature influences the PSP data. In the first large demonstration of uPSP in 2015 on an NESC-, AETC-sponsored wind tunnel test, lifetime PSP results highlighted the influence the model temperature had on the PSP data. A best practice of heat soaking the model before acquiring calibration images was followed during the test campaign presented in this paper. An infrared thermography camera and thermocouples were installed in the model to collect more details of the model surface temperature. Data processing schemes for uPSP are still in development but will be briefly presented here as well.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN76119 , AIAA SciTech Forum; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
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  • 3
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    Propagation predictions for the HF-range by the Research Institute of the Deutsche Bundespost (1979)
    In:  CASI
    Details
    Publication Date: 2009-11-16
    Description: Long term and short term HF propagation prediction service is described. The long term prediction method is computer based. The short term prediction method is still a manual method which relies mainly on a number of continuous field strength recordings and on the forecaster's ability to interpret the recordings and to combine this information with all available solar-geophysical data. Examples of the predictions are given and are compared with actually observed HF propagation conditions.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 25-43
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  • 4
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    A circuit model for electromagnetic properties of waveguide arcs (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: A dielectric model of waveguide arcs is presented to relate measurable electromagnetic quantities to the physical parameters characterizing the breakdown process.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 193-195
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  • 5
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    Assessment of 20 kW S-band transmitter (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The performance history of the 20-kW S-band transmitter, installed at three 64-meter antennas and six 26-meter antennas in the DSN, is reviewed. A number of failures and discrepancy reports are characteristic of the wearout phase of a failure curve. The type of failures are reviewed and four options toward reducing the number and cost of failures are reviewed. These are: existing (no change), refurbish, redesign and replacement. The options are compared on a ten year life cycle cost basis using FY77 expenditures for existing equipment as a base. It was concluded that benefits, in terms of reduction of outrage time, increase with an increase of expenditure toward improvement.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 186-192
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  • 6
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    Microwave time delays in the DSN 34- and 64-meter antennas (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The results and methods used to derive data for the recent changes to the DSN 34- and 64-m stations at both S- and X-band frequencies are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 183-185
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  • 7
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    DSN energy data base preliminary design (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The design and implementation of a computerized data base created to support the DSN Energy Conservation Project with data relating to energy use at Goldstone Deep Space Communications Complex are described. The results of development work to date, are presented along with work currently in progress or in the planning stage.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: The Deep Space Network; p 167-181
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  • 8
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    DSS 13 antenna monitor system (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The development of a monitor system for the DSS 13 antenna is presented. The system checks for accumulator pressures, differential pressures, wind velocity, power supplies, fluid temperatures, and fluid levels. It was concluded that the system performed properly in high winds and correctly reported all malfunctions.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 138-140
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  • 9
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    Carrier tracking loop performance in the presence of strong CW interference (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: Research on the behavior of the carrier tracking loop exposed to a continuous wave irradiation along with Bruno's closed form of approximation for the loop phase error are described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 130-137
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  • 10
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    Costas loop demodulation of suppressed carrier BPSK signals in the DSN environment: Experimental results obtained at TDL (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: Suppressed carrier binary phase-shift keyed (BPSK) signalling is currently being considered as a design alternative for future DSN telemetry in the multimegabit range. Carrier tracking of such signals is usually achieved by a Costas loop, as opposed to the ordinary phase lock loop. A Costas loop capable of demodulating BPSK signals with data rates up to 1 Msps was designed and constructed and its Doppler tracking performance with respect to a Block 3 receiver was tested at the Telecommunications Development Laboratory (TDL). The compatibility of suppressed carrier signalling with the current radiometric system, specifically Doppler tracking and ranging, was investigated. The experimental results obtained to-date with respect to Doppler tracking are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 94-104
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  • 11
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    Feasibility of inertialess conscan utilizing modified DSN feedsystems (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The closed-loop conical-scan (conscan) technique has proven to be a useful method for pointing the DSN antennas more accurately than is possible by open-loop methods. As presently implemented, the antenna beam is scanned about the received signal direction by physical movement of the antenna. While straightforward, this approach has at least two disadvantages. Firstly, because of structural distortions, finite angle encoder resolution, and drive servo response, the actual antenna beam direction only approximates the commanded beam direction. Secondly, because of the large mass moved during scan, the rate of scan is severely restricted. If there are significant gain or signal level variations during a scan period, the conscan system interprets these variations as antenna pointing error. Both of these disadvantages would be alleviated in an inertialess conscan system in which the beam scanning was performed electronically. Recently, standard JPL antenna feedhorn software was upgraded to calculate, among other things, asymmetric corrugated horn radiation patterns of the type that would be needed for electronic beam scan. The required horn excitation is discussed and the results were described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 85-93
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  • 12
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    Antenna feedhorn software upgrade (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The HYBRIDHORN computer program was developed to serve as an item of general purpose antenna feedhorn design and analysis software. The formulation contains a small flare angle approximation which is subject to question for designs such as the S- and X-band feedhorn. Additionally, the original formulation did not allow azimuthal variation indexes other than unity. The HYBRIDHORN program was upgraded to correct both of these deficiencies. A large flare angle formulation was found. In the upgrade, all of the major program elements were converted to Univac 1108 compatible structured FORTRAN (SFTRAN) for ease of software maintenance. The small and large angle formulations are described and sample numerical results are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 75-84
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  • 13
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    Some effects of quantization on a noiseless phase-locked loop (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: If the VCO of a phase-locked receiver is to be replaced by a digitally programmed synthesizer, the phase error signal must be sampled and quantized. Effects of quantizing after the loop filter (frequency quantization) or before (phase error quantization) are investigated. Constant Doppler or Doppler rate noiseless inputs are assumed. The main result gives the phase jitter due to frequency quantization for a Doppler-rate input. By itself, however, frequency quantization is impractical because it makes the loop dynamic range too small.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 58-66
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  • 14
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    Recovering the spectrum of a narrow-band process from syncopated samples (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: A nonuniform sampling strategy, phase quadrature sampling, in which a process of bandwith B is sampled at rate B in each of two channels where the two channels are pi/2 out of phase at frequency B is described. Phase quadrature sampling is a special case of sampling, where the phase between channels is fixed but arbitrary. A simple method for recovering the spectrum of the input process from syncopated samples is derived. The derivation indicates what values of phase between channels result in lossless sampling.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 47-50
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  • 15
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    Effects of D region ionization on radio wave propagation (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The effects of anomalous D region ionization upon radio wave propagation are described for the main types of disturbances: sudden ionospheric disturbances, relativistic electron events, magnetic storms, auroral disturbances, polar cap events, and stratospheric warmings. Examples of radio wave characteristics for such conditions are given for the frequencies between the extremely low (3-3000 Hz) and high (3-30 MHz) frequency domains. Statistics on the disturbance effects and radio wave data are given in order to contribute towards the evaluation of possibilities for predicting the radio effects.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 617-654
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  • 16
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    Forecasts of geomagnetic activities and HF radio propagation conditions made at Hiraiso/Japan (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The Hiraiso Branch of RRL prediction techniques are summarized separately for the 27 day recurrent storm and the flare-associated storm. The storm predictions are compared with the actual geomagnetic activities in two ways. The first one is the comparison on a day to day basis. In the second comparison, the accuracy of the storm predictions during 1965-1976 are evaluated. In addition to the storm prediction, short-term predictions of HF radio propagation conditions are conducted at Hiraiso. The HF propagation predictions are briefly described as an example of the applications of the magnetic storm prediction.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 182-204
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  • 17
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    Estimation of solar flame influence on radio circuit transmission loss (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A provisional method for determining the hours and frequencies at which solar flares cause major radiopath absorption increase is presented. This technique is incorporated in a computer program for monthly radio propagation prediction.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 67-71
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  • 18
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    PROPHET: An applicaton of propagation forecasting principles (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A propagation assessment and forecasting terminal, PROPHET, is described. The terminal is a key element of the environmental prediction and assessment system which uses real time solar/geophysical data to provide real time knowledge of propagation conditions. The terminal uses models to translate data from satellite and ground based sources into performance predictions for specific systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 312-321
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  • 19
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    Radio disturbance warning issuance system (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A radio disturbance warning issuance system was introduced in the Hiraiso Branch of the Radio Research Laboratories in 1972 to reconstruct the current radio disturbance warning service as a social information service. A description of the new ideas which were experimentally systematized by means of an electronic computer is presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 223-228
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  • 20
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    Ionosphere-reflected propagation (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The predictability of those ionospheric parameters relevant to ionosphere-reflected communications is considered along with their optimum utilization. Several excellent original articles and review papers which have been published from time to time dealing with the long term and short term forecasting of ionospheric parameters, radio systems, and modelling needs for ionospheric communications, are covered.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 203-216
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  • 21
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    Transionospheric propagation predictions (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The current status and future prospects of the capability to make transionospheric propagation predictions are addressed, highlighting the effects of the ionized media, which dominate for frequencies below 1 to 3 GHz, depending upon the state of the ionosphere and the elevation angle through the Earth-space path. The primary concerns are the predictions of time delay of signal modulation (group path delay) and of radio wave scintillation. Progress in these areas is strongly tied to knowledge of variable structures in the ionosphere ranging from the large scale (thousands of kilometers in horizontal extent) to the fine scale (kilometer size). Ionospheric variability and the relative importance of various mechanisms responsible for the time histories observed in total electron content (TEC), proportional to signal group delay, and in irregularity formation are discussed in terms of capability to make both short and long term predictions. The data base upon which predictions are made is examined for its adequacy, and the prospects for prediction improvements by more theoretical studies as well as by increasing the available statistical data base are examined.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 217-245
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  • 22
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    Potential prediction needs in support of energy systems (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The relationship between emerging energy systems and the natural environment is discussed, including selected examples to show that energy systems are tied to global solar terrestrial processess. The interdependence of resources, technology, and environmental impact is considered in terms of needed geophysical, atmospheric, and solar terrestrial data inputs. The need for long term basic research on the solar terrestrial system is emphasized.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 198-202
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  • 23
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    Radio propagation prediction services in Japan (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Japanese prediction services for HF radio communications are outlined in relation to prediction method, performance and evaluation. The current prediction is based on the CCIR interim method with some modifications matching to a computer system. The principal service is the monthly median prediction issued regularly three months in advance for various communication circuits. A daily prediction for short distance circuits is being prepared by using real time ionospheric sounding data. An evaluation theory and practice is expected to be introduced in the future prediction service.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 212-222
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  • 24
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    Long term solar activity and ionospheric prediction services rendered by the National Physical Laboratory, New Delhi (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The data base used in solar and ionospheric prediction services is described. Present prediction techniques are discussed and compared with actual observations. Future prediction techniques using computers are also discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 118-133
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  • 25
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    The French short term radiopropagation predictions in the decameter band (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Weekly and daily predictions of the ionospheric characteristics relevant to radio propagation are considered. A description of the techniques involved is given as well as examples showing how the prediction messages are prepared. The short term predictions are confined to restricted geographical areas and are relevant to radio circuits whose terminators are both located inside the same zone. They can be used with a reasonable approximation for circuits less than 3000 km of length whose reflection point lies within a given zone.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 12-24
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  • 26
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    Airborne East Coast/Midwest urban survey at 121.5/243 MHz (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Results of an airborne RF interference measurement survey of the emergency-distress, Search and Rescue frequency bands at 121.5 and 243 MHz at an altitude of 25,000 ft over the U.S. East Coast and Midwest urban areas are presented. Included are a series of minutely median profile plots of antenna-noise temperature computed from RF interference power measurements at the output terminal of a quarter-wavelength monopole antenna, for both daytime and nighttime observations. The greatest value, 450,000 K, of minutely median temperature was recorded over New York City at 121.5 MHz during the day. East Coast urban areas exhibited a day-night effect at 121.5 MHz, where nighttime observations had a median value of 8.6-dB below daytime values; Midwest counterparts did not exhibit a significant day-night effect at 121.5 MHz.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Electromagnetic Compatibility; EMC-21; May 1979
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  • 27
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    Solving the current element problem over lossy half-space without Sommerfeld integrals (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An approach is presented for efficient computation of the vector potentials arising in the problem of a current element radiating over a lossy half-space. The present approach departs from the conventional ones in that it works primarily with the transform domain representations rather than with the Sommerfeld integrals which are the corresponding spatial domain counterparts. The key step in the present method is to approximate the transforms using a suitable approximation which is valid for a wide range of parameters of practical interest. The approximated transforms can be inverted in a closed form for the horizontal component of the vector potentials and can be expressed in a computationally efficient form for the vertical component. Numerical results illustrating the accuracy of the method are presented and some estimates of comparative computational times are also included.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-27; Nov. 197
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  • 28
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    A device model for the tandem junction solar cell (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A conceptual device model has been developed to explain operation of the tandem junction cell (TJC) when back contacts only are used. Operation and parameters of the cell are explained by transistor action. Experimental observations are presented which confirm that current is collected for carrier generation in the front uncontacted n(plus) region. The model should be useful as a guideline to optimize the TJC by application of transistor design principles.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IEEE Transactions on Electron Devices; ED-26; Sept
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  • 29
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    The importance of surface recombination and energy-bandgap narrowing in p-n-junction silicon solar cells (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Experimental data demonstrating the sensitivity of open-circuit voltage to front-surface conditions are presented for a variety of p-n-junction silicon solar cells. Analytical models accounting for the data are defined and supported by additional experiments. The models and the data imply that a) surface recombination significantly limits the open-circuit voltage (and the short-circuit current) of typical silicon cells, and b) energy-bandgap narrowing is important in the manifestation of these limitations. The models suggest modifications in both the structural design and the fabrication processing of the cells that would result in substantial improvements in cell performance. The benefits of one such modification - the addition of a thin thermal silicon-dioxide layer on the front surface - are indicated experimentally.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IEEE Transactions on Electron Devices; ED-26; Sept
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  • 30
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    Evaluation of models to predict insolation on tilted surfaces (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An empirical study was performed to evaluate the validity of various insolation models which employ either an isotropic or an anisotropic distribution approximation for sky light when predicting insolation on tilted surfaces. Data sets of measured hourly insolation values were obtained over a 6-month period using pyranometers which received diffuse and total solar radiation on a horizontal plane and total radiation on surfaces tilted toward the equator at 37 degrees and 60 degrees angles above the horizon. Data on the horizontal surfaces were used in the insolation models to predict insolation on the tilted surface; comparisons of measured vs calculated insolation on the tilted surface were examined to test the validity of the sky light approximations. It was found that the Liu-Jordan isotropic distribution model provides a good fit to empirical data under overcast skies but underestimates the amount of solar radiation incident on tilted surfaces under clear and partly cloudy conditions.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Energy; 23; 2, 19; 1979
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  • 31
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    A simple theory of back-surface-field /BSF/ solar cells (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An earlier calculation of the I-V characteristics of solar cells contains a mistake. The current generated by light within the depletion layer is too large by a factor of 2. When this mistake is corrected, not only are all previous conclusions unchanged, but the agreement with experiment becomes better. Results are presented in graphical form of new computations which not only take account of the factor of 2, but also include more recent data on material parameters.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Journal of Applied Physics; 50; Aug. 197
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  • 32
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    Digital techniques for ULF wave polarization analysis (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Digital power spectral and wave polarization analysis are powerful techniques for studying ULF waves in the earth's magnetosphere. Four different techniques for using the spectral matrix to perform such an analysis have been presented in the literature. Three of these techniques are similar in that they require transformation of the spectral matrix to the principal axis system prior to performing the polarization analysis. The differences in the three techniques lie in the manner in which determine this transformation. A comparative study of these three techniques using both simulated and real data has shown them to be approximately equal in quality of performance. The fourth technique does not require transformation of the spectral matrix. Rather, it uses the measured spectral matrix and state vectors for a desired wave type to design a polarization detector function in the frequency domain. The design of various detector functions and their application to both simulated and real data will be presented.
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  • 33
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    Calculated scan characteristics of a large spherical reflector antenna (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A previously published numerical method to calculate the radiation properties of parabolic reflectors has been modified to also include very large spherical reflectors. The method has been verified by comparing the calculated and the measured results for a 120-wavelength spherical reflector.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-27; May 1979
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    Low-cost encapsulation materials for terrestrial solar cell modules (1979)
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    Publication Date: 2011-08-17
    Description: The paper presents the findings of material surveys intended to identify low cost materials which could be functional as encapsulants (by 1986) for terrestrial solar cell modules. Economic analyses have indicated that in order to meet the low cost goal of $2.70 per sq m, some or all of the following material technologies must be developed or advanced: (1) UV screening outer covers; (2) elastomeric acrylics; (3) weatherproofing and waterproofing of structural wood and paper products; (4) transparent UV stabilizers for the UV-sensitive transparent pottants; and (5) cost-effective utilization of silicone and fluorocarbon materials.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Energy; 22; 4, 19; 1979
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  • 35
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    False lock performance of quadriphase receivers (1979)
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    Publication Date: 2011-08-17
    Description: Quadriphase receivers, like biphase receivers, have the ability to false lock on a sideband on the data modulation. The theory associated with this phenomenon for receivers of binary phase-shift-keying (BPSK), using Costas loop demodulation, has recently been documented in the literature. This paper considers the corresponding theory for receivers of balanced quadriphase-shift-keying (QPSK) employing a quadriphase Costas loop (or equivalent fourth-power loop) for demodulation. Specific closed form expressions for false lock performance are developed and numerically evaluated for the particular case of single pole arm filters and an NRZ data format for each of the two statistically independent quadrature modulations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-27; Nov. 197
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  • 36
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    Digital and analog communication systems (1979)
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    Publication Date: 2011-08-17
    Description: The book presents an introductory treatment of digital and analog communication systems with emphasis on digital systems. Attention is given to the following topics: systems and signal analysis, random signal theory, information and channel capacity, baseband data transmission, analog signal transmission, noise in analog communication systems, digital carrier modulation schemes, error control coding, and the digital transmission of analog signals.
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    Solar cell spectral response characterization (1979)
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    Publication Date: 2011-08-17
    Description: The absolute spectral response of solar cells is reported in the 400-1000-nm spectral region. Measurements were performed using two different types of monochromatic sources: amplitude-stabilized CW laser lines and interference filters with an incandescent lamp. Both types of calibration procedures use electrical substitution radiometry as the basis of traceability to absolute SI units. The accuracy of the calibration is shown to be limited by the nonideal characteristics of the solar cells themselves, specifically spatial nonuniformities and nonlinearities induced by high light levels.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Applied Optics; 18; Dec. 1
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  • 38
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    Radiation energy conversion in space (1979)
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    Publication Date: 2011-08-17
    Description: Topics discussed at the third NASA conference on radiant energy conversion are reviewed. The unconcentrated-photovoltaic-generation version of a solar power satellite is described, noting that it will consist of a 21.3 x 5.3-sq-km silicon-solar-cell array expected to provide 17 Gw of electrical power, with 1 km in diam transmitters oriented to beam 2.45 GHz microwave power to two receiving/rectifying 'rectennas' on earth. The Solares space-energy-system concept, designed for providing a large fraction of the world's energy needs at costs comparable to those of future coal/nuclear alternative, is considered, as are subsystems for improving the economics of the solar power satellite. A concept proposing the use of relativistic-electron-storage rings for electron-beam energy transmission and storage, and a report on the production of a high temperature plasma with concentrated solar radiation are taken into account. Laser-conversion systems, including the direct-solar-pumped space laser, and the telec-powered spacecraft, are discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Astronautics and Aeronautics; 17; Mar. 197
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  • 39
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    Application of the superposition principle to solar-cell analysis (1979)
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    Publication Date: 2011-08-17
    Description: The superposition principle of differential-equation theory - which applies if and only if the relevant boundary-value problems are linear - is used to derive the widely used shifting approximation that the current-voltage characteristic of an illuminated solar cell is the dark current-voltage characteristic shifted by the short-circuit photocurrent. Analytical methods are presented to treat cases where shifting is not strictly valid. Well-defined conditions necessary for superposition to apply are established. For high injection in the base region, the method of analysis accurately yields the dependence of the open-circuit voltage on the short-circuit current (or the illumination level).
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IEEE Transactions on Electron Devices; ED-26; Mar. 197
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  • 40
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    Interim radio spectrum surveillance station (1979)
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    Publication Date: 2011-08-17
    Description: Radio frequency interference at NASA's deep space stations has become a serious problem. A radio spectrum surveillance capability at these stations is needed to determine the sources of interference so that preventative measures can be taken. The first phase of a program to develop this capability was the development of a low-cost surveillance station now in operation at the Goldstone Space Communication Complex near Barstow, California. This interim surveillance station is described and findings from the use of this equipment are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 99-107
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  • 41
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    Minimizing the RMS surface distortions from gravity loadings of the 34-m HA-DEC antenna for deep space missions (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The computer analysis of the 34-m HA-DEC antenna by the IDEAS program provided the rms distortions of the surface panels support points for full gravity loadings in the three directions of the basic coordinate system of the computer model. The rms distortions for the gravity vector not in line with any of the three basic directions were solved and contour plotted starting from three surface panels setting declination angle. By inspections of the plots, it was concluded that the setting or rigging angle of -15 degrees declination minimized the rms distortions for sky coverage of plus or minus 22 declination angles to 10 degrees of ground mask.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 94-98
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  • 42
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    Comparison of two total energy systems for a diesel power generation plant (1979)
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    Publication Date: 2011-08-17
    Description: The capabilities and limitations, as well as the associated costs for two total energy systems for a diesel power generation plant are compared. Both systems utilize waste heat from engine cooling water and waste heat from exhaust gases. Pressurized water heat recovery system is simple in nature and requires no engine modifications, but operates at lower temperature ranges. On the other hand, a two-phase ebullient system operates the engine at constant temperature, provides higher temperature water or steam to the load, but is more expensive.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: The Deep Space Network; p 89-93
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  • 43
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    Preliminary report on DSN system performance under local weather effects (1979)
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    Publication Date: 2011-08-17
    Description: Local effects of precipitation are studied, and a simplified working model is developed. Experimental results obtained by simulation are in good agreement with the model, showing that it could be an important contribution to system degradation. If this is confirmed, some suggestions for improvement are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 82-88
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  • 44
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    New X-band antenna feeds for the DSN 64-meter stations (1979)
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    Publication Date: 2011-08-17
    Description: New X-band antenna feed assemblies with dual-polarization capability are being implemented in the DSN 64-meter stations. Together with dual X-band traveling wave masers, they permit the simultaneous reception of right- and left-hand circular polarization from the Voyager spacecraft. The new feed also includes a dual hybrid mode feedhorn which increases the antenna gain by 0.36 dB over the present feedhorn.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 71-74
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  • 45
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    A generalization of binary minimum shift keying and staggered quadriphase shift keying modulation (1979)
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    Publication Date: 2011-08-17
    Description: A generalized modulation scheme, which includes minimum shift keying (MSK) and staggered quadriphase shift keying (SQPSK) as special cases, is analyzed. The general modulator is realized as a one-input, two-output sequence transducer whose outputs select the carrier signal for each band. This form of the modulator has the practical advantage of not requiring any RF filtering since there is no actual mixing of the carriers with the modulating signals. It is shown that the optimum demodulator (whether hard-decision or soft-decision) always can make its decisions from the received waveform over two bands when the interference is additive white Gaussian noise, thus generalizing a well-known result for hard decision demodulation of MSK and SQPSK signals. The power spectra of MSK and SQPSK signals are derived to isolate the role played by coherency between the modulating signals and the carriers.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 26-40
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  • 46
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    A two-dimensional thermal analysis of a new high-performance tubular solar collector (1979)
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    Publication Date: 2011-08-17
    Description: The first of two articles are presented which describe and analyze the thermal performance of a vacuum tube solar collector. The assumptions and mathematical modeling are presented. The problem is reduced to the formulation of two simultaneous linear differential equations characterizing the collector thermal behavior. After applying the boundary conditions, a general solution is obtained which is found similar to the general Hottel, Whillier and Bliss form but with a complex flow factor.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: The Deep Space Network; p 116-131
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  • 47
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    Radio frequency carrier arraying for near maximum carrier signal-to-noise ratio improvement (1979)
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    Publication Date: 2011-08-17
    Description: Radio frequency arraying of several receiving systems provides signal-to-noise ratio improvement relative to a single receiving system. This report considers radio frequency carrier arraying which provides near maximum signal-to-noise ratio improvement for carrier reception and demodulation.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 99-106
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  • 48
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    The updated algorithm of the Energy Consumption Program (ECP): A computer model simulating heating and cooling energy loads in buildings (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The energy Comsumption Computer Program was developed to simulate building heating and cooling loads and compute thermal and electric energy consumption and cost. This article reports on the new additional algorithms and modifications made in an effort to widen the areas of application. The program structure was rewritten accordingly to refine and advance the building model and to further reduce the processing time and cost. The program is noted for its very low cost and ease of use compared to other available codes. The accuracy of computations is not sacrificed however, since the results are expected to lie within + or - 10% of actual energy meter readings.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: The Deep Space Network; p 107-115
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  • 49
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    Coding for optical channels (1979)
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    Publication Date: 2011-08-17
    Description: In a previous paper Pierce considered the problem of optical communication from a novel viewpoint, and concluded that performance will likely be limited by issues of coding complexity rather than by thermal noise. This paper reviews the model proposed by Pierce and presents some results on the analysis and design of codes for this application.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 70-77
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  • 50
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    Submicrosecond comparison of intercontinental clock synchronization by VLBI and the NTS satellite (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The intercontinental clock synchronization capabilities of Very Long Baseline Interferometry (VLBI) and the Navigation Technology Satellite (NTS) were compared in May 1978 by using both methods to synchronize the cesium clocks at the NASA Deep Space Net complexes at Madrid, Spain, and Goldstone, California. The VLBI experiments used the Wideband VLBI Data Acquisition System. The Navigation Technology Satellites were used with NTS Timing Receivers developed by the Goddard Space Flight Center. The two methods agreed at about the one-half microsecond level. The VLBI system also obtained long-term stability information on the HP5061A004 cesium standards by measuring delta T/T over four 3- to 4-day intervals, obtaining stability estimates of (1 + or - 1)x10 to the -13th power for the combined timing systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 64-69
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  • 51
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    Comparison of phase modulation systems (1979)
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    Publication Date: 2011-08-17
    Description: Comparison of the energy to noise ratio necessary to obtain a given modulation bit error probability has indicated that three-phase modulation is about 0.75 db superior to four-phase. It is shown that this apparent superiority results entirely from the greater bandwidth required by the three-phase system for the same bit transmission rate. Two further comparison criteria are proposed, which are based on the cut-off rate R sub 0 of the discrete channel created by the modulation system. For the criterion which constrains both the bandwidth and transmitted power, it is shown that four-phase modulation is always superior to three-phase modulation. The conclusion is that three-phase modulation offers no practical advantage over four-phase modulation.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 57-63
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  • 52
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    DSN ground communications facility (1979)
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    Publication Date: 2011-08-17
    Description: A functional description of the Ground Communications Facilities and its relationships with other elements of the Deep Space Network and NASA Communications Network is presented together with development objectives and goals and comments on implementation activities in support of flight projects.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 19-28
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  • 53
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    DSN command system Mark 3-78 (1979)
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    Publication Date: 2011-08-17
    Description: The Deep Space Network Command System Mark III-78 implementation and functional operation are described. Software upgrade enables expanded storage capacity in the Deep Space Station Command Processor Assembly. Store-and-forward command data handling is operational for Voyager and Helios. Near-real-time command data handling was retained for Viking and Pioneer.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 11-18
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  • 54
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    The NASA radar entomology program at Wallops Flight Center (1979)
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    Publication Date: 2016-06-07
    Description: NASA contribution to radar entomology is presented. Wallops Flight Center is described in terms of its radar systems. Radar tracking of birds and insects was recorded from helicopters for airspeed and vertical speed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radar, Insect Population Ecology, and Pest Management; p 161-169
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    Quantitative Analysis of Radar Returns from Insects (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: When a number of flying insects is low enough to permit their resolution as individual radar targets, quantitative estimates of their aerial density are developed. Accurate measurements of heading distribution using a rotating polarization radar to enhance the wingbeat frequency method of identification are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Wallops Flight Center Radar, Insect Population Ecology, and Pest Management; p 131-158
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    Radar program at Western Cotton Research Laboratory (1979)
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    Publication Date: 2016-06-07
    Description: An entomological radar similar to those used in England is developed. The radar will detect insects in flight and the data will be used for studying insect dispersal.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Wallops Flight Center Radar, Insect Population Ecology, and Pest Management; p 159-160
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    Radar observation of known and unknown clear echoes (1979)
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    Publication Date: 2016-06-07
    Description: Target cross-section as a function of wavelength for known insects, known bird, and dot targets is presented. Tracking data using the time series analysis was tabulated for known birds. Examples were selected from these early works to give entomologists some indication of the types of information that are available by radar as well as examples of the different sources of clear-air radar backscatter.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Wallops Flight Center Radar, Insect Population Ecology, and Pest Management; p 113-130
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    Theoretical modelling and experimental data matching for active and passive microwave remote sensing of Earth terrain (1979)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Two theoretical models were developed to characterize terrain media: a random medium with a variance, a horizontal correlation length; and a homogeneous dielectric containing discrete scatterers. The earth terrain is modelled as layers of such scattering media bounded by air above and half-space below. Matching the theoretical results with experimental data collected from vegetation and snow-ice fields shows that: (1) for observation angles near nadir, rough surface effects are important; (2) for snow-ice field the horizontal correlation length is greater than the vertical correlation length whereas for vegetation field their relative sizes depend on the types of vegetation; (3) the vertically polarized backscattering cross-section is always larger than the horizontally polarized backscattering cross-section for half-space scattering media; (4) for snow field displaying diurnal change, a three-layer model including a thin top layer caused by sunlight illumination must be used; and (5) for a random medium with equal horizontal and vertical correlation lengths, the measured data can also be matched with a corresponding discrete scatterer model.
    Keywords: COMMUNICATIONS AND RADAR
    Type: AGARD Terrain Profiles and Contours in Electromagnetic Wave Propagation; 8 p
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  • 59
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    Photovoltaic system criteria documents. Volume 5: Safety criteria for photovoltaic applications (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Methodology is described for determining potential safety hazards involved in the construction and operation of photovoltaic power systems and provides guidelines for the implementation of safety considerations in the specification, design and operation of photovoltaic systems. Safety verification procedures for use in solar photovoltaic systems are established.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-CR-183320 , JPL-5250-3-VOL-5 , NAS 1.26:183320
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    Photovoltaic system criteria documents. Volume 3: Environmental issues and evaluation criteria for photovoltaic applications (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The environmental issues and evaluation criteria relating to the suitability of sites proposed for photovoltaic (PV) system deployment are identified. The important issues are defined, briefly discussed and then developed into evaluation criteria. System designers are provided with information on the environmental sensitivity of PV systems in realistic applications, background material which indicates the applicability of the siting issues identified, and evaluation criteria are defined to facilitate the selection of sites that maximize PV system operation.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-CR-183318 , JPL-5250-3-VOL-3 , NAS 1.26:183318
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    Photovoltaic system criteria documents. Volume 1: Guidelines for evaluating the management and operations planning of photovoltaic applications (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Guidelines are provided to the Field Centers for organization, scheduling, project and cost control, and performance in the areas of project management and operations planning for Photovoltaics Test and Applications. These guidelines may be used in organizing a T and A Project Team for system design/test, site construction and operation, and as the basis for evaluating T and A proposals. The attributes are described for project management and operations planning to be used by the Field Centers. Specifically, all project management and operational issues affecting costs, schedules and performance of photovoltaic systems are addressed. Photovoltaic tests and applications include residential, intermediate load center, central station, and stand-alone systems. The sub-categories of system maturity considered are: Initial System Evaluation Experiments (ISEE); System Readiness Experiments (SRE); and Commercial Readiness Demonstration Projects (CRDP).
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-CR-183316 , JPL-5250-3-VOL-1 , NAS 1.26:183316
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    Photovoltaic system criteria documents. Volume 4: Review criteria for photovoltaic applications (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Guidelines are provided for the organization, preparation and conduct of program reviews for photovoltaic applications. These criteria apply to all photovoltaic applications. They include, but are not limited to, the following: (1) Conceptual design review; (2) Preliminary design review; (3) Critical design review; and (4) Operational readiness review. Contract goal's and objectives are met through program monitoring for cost, schedule, and performance for both managerial and technical elements for all PV applications activities.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-CR-183319 , JPL-5250-3-VOL-4 , NAS 1.26:183319
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    Photovoltaic system criteria documents. Volume 2: Quality assurance criteria for photovoltaic applications (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Quality assurance criteria are described for manufacturers and installers of solar photovoltaic tests and applications. Quality oriented activities are outlined to be pursued by the contractor/subcontractor to assure the physical and operational quality of equipment produced is included. In the broad sense, guidelines are provided for establishing a QA organization if none exists. Mainly, criteria is provided to be considered in any PV quality assurance plan selected as appropriate by the responsible Field Center. A framework is established for a systematic approach to ensure that photovoltaic tests and applications are constructed in a timely and cost effective manner.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-CR-183317 , JPL-5250-3-VOL-2 , NAS 1.26:183317
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    Results of a utility survey of the status of large wind turbine development (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Wind energy conversion systems were surveyed from a utility viewpoint to establish the state of the art with regard to: (1) availability of the type of machines; (2) quality of power generation; (3) suitability for electrical grid; (4) reliability; and (5) economics. Of the 23 designs discussed, 7 have vertical axis wind turbines, 9 have upwind horizontal axis turbines, and 7 have downwind horizontal axis turbines.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 363-374
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    Large, low cost composite wind turbine blades (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A woven roving E-glass tape, having all of its structural fibers oriented across the tape width was used in the manufacture of the spar for a wind turbine blade. Tests of a 150 ft composite blade show that the transverse filament tape is capable of meeting structural design requirements for wind turbine blades. Composite blades can be designed for interchangeability with steel blades in the MOD-1 wind generator system. The design, analysis, fabrication, and testing of the 150 ft blade are discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 309-324
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    The use of wood for wind turbine blade construction (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The interrelationships between moisture and wood, conditions for dry rot spore activity, the protection of wood fibers from moisture, wood resin composites, wood laminating, quality control, and the mechanical properties of wood are discussed. The laminated veneer and the bonded sawn stock fabrication techniques, used in the construction of a turbine blade with a monocoque 'D' section forming the leading edge and a built up trailing edge section, are described. A 20 foot root end sample complete with 24 bonded-in studs was successfully subjected to large onetime loads in both the flatwise and edgewise directions, and to fatigue tests. Results indicate that wood is both a viable and advantageous material for use in wind turbine blades. The basic material is reasonably priced, domestically available, ecologically sound, and easily fabricated with low energy consumption.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 293-308
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    Evaluation of an operating MOD-OA 200 kW wind turbine blade (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Operating loads and structural damage were monitored during operation of the MOD-OA electric generating system. The turbine was damaged locally between stations 48 and 125 after 2.8 million rotations. Loads due to degraded yaw stiffness and fretting at rib station 48 were identified as primary to this distress. The repaired blades operated an additional 4.8 million rotations without problems.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 239-265
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  • 68
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    Cost of energy evaluation (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The estimated cost per kilowatt hour, the wind resources in the utilities service area, and the reliability of the units are considered in computing the cost of energy of the wind turbine generator system.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 397-402
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  • 69
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    Status of the Southern California Edison Company 3 MW Wind Turbine Generator (WTG) demonstration project (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: To demonstrate the concept of utility scale electricity production from a high wind energy resource, a program was initiated to construct and test a 3 megawatt (3,000 kW) Schachle wind turbine generator near Palm Springs, California. The background and current status of this program are presented along with a summary of future planned program activities.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 355-362
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  • 70
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    Blade design and operating experience on the MOD-OA 200 kW wind turbine at Clayton, New Mexico (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two 60 foot long aluminum wind turbine blades were operated for over 3000 hours on the MOD-OA wind turbine. The first signs of blade structural damage were observed after 400 hours of operation. Details of the blade design, loads, cost, structural damage, and repair are discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Large Wind Turbine Design Characteristics and R and D Requirements; p 225-238
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  • 71
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    Alcoa wind turbines (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An overview of Alcoa's wind energy program is given with emphasis on the the development of a low cost, reliable Darrieus Vertical Axis Wind Turbine System. The design layouts and drawings for fabrication are now complete, while fabrication and installation to utilize the design are expected to begin shortly.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 155-171
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  • 72
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    Specification, siting and selection of large WECS prototypes (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The development of large-scale windpowered systems is outlined. Topics discussed include: prototype specifications development, site selection process, and selection of prototype contractor.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 89-102
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  • 73
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    Design evolution of large wind turbine generators (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: During the past five years, the goals of economy and reliability have led to a significant evolution in the basic design--both external and internal--of large wind turbine systems. To show the scope and nature of recent changes in wind turbine designs, development of three types are described: (1) system configuration developments; (2) computer code developments; and (3) blade technology developments.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Large Wind Turbine Design Characteristics and R and D Requirements; p 25-33
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  • 74
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    Computer modeling of a two-junction, monolithic cascade solar cell (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The theory and design criteria for monolithic, two-junction cascade solar cells are described. The departure from the conventional solar cell analytical method and the reasons for using the integral form of the continuity equations are briefly discussed. The results of design optimization are presented. The energy conversion efficiency that is predicted for the optimized structure is greater than 30% at 300 K, AMO and one sun. The analytical method predicts device performance characteristics as a function of temperature. The range is restricted to 300 to 600 K. While the analysis is capable of determining most of the physical processes occurring in each of the individual layers, only the more significant device performance characteristics are presented.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 267-281
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  • 75
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    An interim report on the NTS-2 solar cell experiment (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Data obtained from the fourteen solar cell modules on the NTS-2 satellite are presented together with a record of panel temperature and sun inclination. The following flight data are discussed: (1) state of the art solar cell configurations which embody improvements in solar cell efficiency through new silicon surface and bulk technology, (2) improved coverslip materials and coverslip bonding techniques, (3) short and long term effects of ultraviolet rejection filters vs. no filters on the cells, (4) degradation on a developmental type of liquid epitaxy gallium-aluminum-arsenide solar cell, and (5) space radiation effects.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 117-129
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  • 76
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    The NASA Lewis Research Center program in space solar cell research and technology (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Progress in space solar cell research and technology is reported. An 18 percent-AMO-efficient silicon solar cell, reduction in the radiation damage suffered by silicon solar cells in space, and high efficiency wrap-around contact and thin (50 micrometer) coplanar back contact silicon cells are among the topics discussed. Reduction in the cost of silicon cells for space use, cost effective GaAs solar cells, the feasibility of 30 percent AMO solar energy conversion, and reliable encapsulants for space blankets are also considered.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Cell High Efficiency and Radiation Damage, 1979; p 1-4
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  • 77
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    Temperature and intensity dependence of the performance of an electron-irradiated (AlGa)As/GaAs solar cell (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The performance of a Hughes, liquid-phase epitaxial 2 centimeter-by-2 centimeter, (AlGa)As/GaAs solar cell was measured before and after irradiations with 1 MeV electrons to fluences of 1 x 10 to the 16th power electrons/sq cm. The temperature dependence of performance was measured over the temperature range 135 to 415 K at each fluence level. In addition, temperature dependences were measured at five intensity levels from 137 to 2.57 mW/sq cm before irradiation and after a fluence of 1 x 10 to the 16th power electrons/sq cm. For the intermediate fluences, performance was measured as a function of intensity at 298 K only.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Cell High Frequency and Radiation Damage, 1979; p 217-226
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  • 78
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    High-energy electron-induced damage production at room temperature in aluminum-doped silicon (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: DLTS and EPR measurements are reported on aluminum-doped silicon that was irradiated at room temperature with high-energy electrons. Comparisons are made to comparable experiments on boron-doped silicon. Many of the same defects observed in boron-doped silicon are also observed in aluminum-doped silicon, but several others were not observed, including the aluminum interstitial and aluminum-associated defects. Damage production modeling, including the dependence on aluminum concentration, is presented.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 185-196
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  • 79
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    Langley program of GaAs solar cells (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A brief overview of the development of GaAs solar cell technology is provided. An 18 to 20 percent AMO efficiency, stability under radiation and elevated-temperature operation, and high power-to-weight ratio are among the factors studied. Cell cost and availability are also examined.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 13-14
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  • 80
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    Modeling of thin, back-wall silicon solar cells (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The performance of silicon solar cells with p-n junctions on the nonilluminated surface (i.e., upside-down or back-wall cells) was calculated. These structures consisted of a uniformly shaped p-type substrate layer, a p(+)-type field layer on the front (illuminated) surface, and a shallow, n-type junction on the back (nonilluminated) surface. A four-layer solar cell model was used to calculate efficiency, open-circuit voltage, and short-circuit current. The effect on performance of p-layer thickness and resistivity was determined. The diffusion length was varied to simulate the effect of radiation damage. The results show that peak initial efficiencies greater than 15 percent are possible for cell thicknesses or 100 micrometers or less. After 10 years of radiation damage in geosynchronous orbit, thin (25 to 50 micrometers thick) cells made from 10 to 100 ohm cm material show the smallest decrease (approximately 10 percent) in performance.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Cell High Efficiency and Radiation Damage, 1979; p 73-78
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  • 81
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    System configuration improvement (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Factors involved in the choice of the system configuration for the wind turbine generator are listed. It was found that choices among the many configuration options can be based strictly upon the resulting cost of energy results. Choices made on that basis also lead to reduced analytical complexity, less hardware complexity and reduced program risk. It was also found that many seemingly minor details turn out to have important impacts that are seen only after design, performance and cost-finding were thoroughly probed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 385-396
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  • 82
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    The Boeing MOD-2 wind turbine system rotor (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: External configuration, environmental, and internal design requirements for the 300 foot diameter MOD-2 rotor are discussed, with emphasis on design details, significance of fatigue strength, design development test results, and conclusions of the preliminary design efforts.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 343-354
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  • 83
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    Structural analysis considerations for wind turbine blades (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Approaches to the structural analysis of wind turbine blade designs are reviewed. Specifications and materials data are discussed along with the analysis of vibrations, loads, stresses, and failure modes.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Large Wind Turbine Design Characteristics and R and D Requirements; p 211-224
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  • 84
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    Large wind energy converter: Growian 3 MW (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The main features of the Growian wind energy converter are presented. Energy yield, environmental impact, and construction of the energy converter are discussed. Reliability of the windpowered system is assessed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 121-132
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  • 85
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    Overview of Federal wind energy program (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The objectives and strategies of the Federal wind energy program are described. Changes in the program structure and some of the additions to the program are included. Upcoming organizational changes and some budget items are discussed, with particular emphasis on recent significant events regarding new approvals.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 1-24
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  • 86
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    Summary of GaAs Solar Cell Performance and Radiation Damage Workshop (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The workshop considered the GaAs solar cell capability and promise in several steps: (1) maximum efficiency; (2) space application; (3) major technology problems (AR coating optimization, contacts); (4) radiation resistance; (5) cost and availability; and (6) alternatives. The workshop believes that GaAs solar cells are fast approaching the fulfillment of their potential as candidates for space cells. A maximum efficiency of 20 to 31 percent AMO can be reasonably expected from GaAs based cells, and this may go a little higher with concentration. The use of concentration in space needs to be more carefully evaluated.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 253-254
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  • 87
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    Shallow-homojunction GaAs solar cells (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Single-crystal GaAs shallow-homojunction solar cells on GaAs or Ge substrates, without Ga sub 1-x Al sub x As window layers, that have conversion efficiencies exceeding 20% at AM1 (17% at AMO). Using a simple theoretical model, good fits were obtained between computer calculations and experimental data for external quantum efficiency and conversion efficiency of cells with different values of n+ layer thickness. The calculations not only yield values for material properties of the GaAs layers composing the cells but will also permit the optimization of cell designs for space and terrestrial applications. Preliminary measurements indicate that the shallow-homojunction cells are resistant to electron irradiation. In the best test so far, bombardment with 1 x 10 to the 16th power/sq cm fluence of 1 MeV electrons reduced the short-circuit current by only about 6%.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Frequency and Radiation Damage, 1979; p 227-233
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  • 88
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    Radiation damage in GaAs solar cells (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Recent results of electron and proton irradiation and annealing of GaAs solar cells are presented along with some implications of these results. A comparison between the energy-levels produced by protons and by electrons which are not stopped in the material indicate that the damage produced by protons and electrons may be qualitatively different. Thus, annealing of proton damage may be very different from the annealing of electron damage.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 201-207
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  • 89
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    Reverse annealing in radiation-damaged, silicon solar cells (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: In order to understand the results in terms of properties of the radiation induced defects, a combination of diffusion length measurements and defect data obtained from Deep Level Transient Spectroscopy were used. The results indicate that the defect at E sub v + 0.30 eV is responsible for the observed reversed annealing. The defect was identified as a boron-oxygen vacancy complex. This identification is a guide to processing efforts aimed at increasing the concentration of these radiation induced defects.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Cell High Efficiency and Radiation Damage, 1979; p 161-171
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  • 90
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    Efficiency of tandem solar cell systems as function of temperature and solar energy concentration ratio (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The results of a comprehensive theoretical analysis of tandem photovoltaic solar cells as a function of temperature and solar concentration ratio are presented. The overall efficiencies of tandem cell stacks consisting of as many as 24 cells having gaps in the 0.7 to 3.6 eV range were calculated for temperatures of 200, 300, 400, and 500 K and for illumination by an AMO solar spectrum having concentration ratios of 1, 100, 500, and 1000 suns. For ideal diodes (A = B = 1), the calculations show that the optimized overall efficiency has a limiting value eta sub opt of approximately 70 percent for T = 200 K and C = 1000; for T = 300 K and C = 1000, this limiting efficiency approaches 60 percent.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 263-265
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  • 91
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    Silicon solar cells for space use: Present performance and trends (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A technology assessment of present performance levels and current fabrication methods and designs is presented.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 101-104
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  • 92
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    High efficiency cell geometry (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A new silicon solar cell is described which has an array of small-area conduction paths to transport current directly through the wafer to metal electrodes on the back. This design eliminates grid shadowing and many of the other losses inherent in conventional cells. Early experimental units without texturing or antireflection coatings show 13.3% efficiency under air-mass-one illumination insolation.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 97-100
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  • 93
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    Design considerations for the Tandem Junction Solar Cell (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Structure and operation of the tandem junction cell (TJC) are described. The impact of using only back contacts is discussed. A model is presented which explains operation of the TJC in terms of transistor action. The model is applied to predict TJC performance as a function of physical parameters.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 79-85
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  • 94
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    Open-circuit voltage improvements in low-resistivity solar cells (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Mechanisms limiting the open-circuit voltage in 0.1 ohm-cm solar cells were investigated. It was found that a rather complicated multistep diffusion process could produce cells with significantly improved voltages. The voltage capabilities of various laboratory cells were compared independent of their absorption and collection efficiencies. This was accomplished by comparing the cells on the basis of their saturation currents or, equivalently, comparing their voltage outputs at a constant current-density level. The results show that for both the Lewis diffused emitter cell and the Spire ion-implanted emitter cell the base component of the saturation current is voltage controlling. The evidence for the University of Florida cells, although not very conclusive, suggests emitter control of the voltage in this device. The data suggest further that the critical voltage-limiting parameter for the Lewis cell is the electron mobility in the cell base.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Solar Cell High Efficiency and Radiation Damage, 1979; p 61-70
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  • 95
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    Limiting process in shallow junction solar cells (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: In extending the violet and nonreflective cell technology to lower resistivities, several processes limiting output power were encountered. The most important was the dark diffusion current due to recombination at the front grid contacts. After removal of this problem by reduction of the silicon metal contact area (to 0.14 percent of the total area), the electric field enhanced junction recombination current J sub r was the main limitation. Alteration of the diffusion profile to reduce the junction field is shown to be an effective means of influencing J sub r. The remaining problems are the bulk recombination in the n+ layer and the surface recombination at the oxide-silicon interface; both of these problems are aggravated by band-narrowing resulting from heavy doping in the diffused layer. Experimental evidence for the main limitations is shown, where increased diffusion temperature is seen to reduce both the influence of the front grid contacts and the junction electric field by increasing the junction depth. The potential for further significant improvement in efficiency appears to be high.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 35-36
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  • 96
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    Solar photovoltaic research and development program of the Air Force Aero Propulsion Laboratory (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Progress is reported in the following areas: laser weapon effects, solar silicon solar cell concepts, and high voltage hardened, high power system technology. Emphasis is placed on solar cells with increased energy conversion efficiency and radiation resistance characteristics for application to satellite power systems.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Solar Cell High Efficiency and Radiation Damage, 1979; p 5-8
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  • 97
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    Simulation studies of multiple large wind turbine generators on a utility network (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The potential electrical problems that may be inherent in the inertia of clusters of wind turbine generators and an electric utility network were investigated. Preliminary and limited results of an analog simulation of two MOD-2 wind generators tied to an infinite bus indicate little interaction between the generators and between the generators and the bus. The system demonstrated transient stability for the conditions considered.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Large Wind Turbine Design Characteristics and R and D Requirements; p 375-384
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  • 98
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    The MOD-1 steel blade (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The design, development, fabrication, testing, and transport of two 100 foot metal blades for the MOD-1 WTS are summarized. Because the metal blade design was started late in the MOD-1 system development, many of the design requirements (allocations) were restrictive for the metal blade concept, particularly the maximum weight requirement. The design solutions required to achieve the weight goal resulted in a labor intensive (expensive) fabrication, particularly for a quantity of only two blades manufactured using minimal tooling.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 325-342
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  • 99
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    WTG Energy Systems' Rotor: Steel at 80 Feet (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The design, specifications, and performance of the 80 foot diameter fixed pitch rotor operating on the MP1-200 wind turbine generator installed as part of the Island of Cuttyhunk's electric power utility grid system are described. This synchronous generating system rated 200 kilowatts at 28 mph wind velocity, and produces constant 60 Hz, 480 VAC current at +/- 1 percent accuracy throughout the machine's operating range. Future R & D requirements and suggestions are included with cost data.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Res. Center Large Wind Turbine Design Characteristics and R and D Requirements; p 285-292
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  • 100
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    Design, fabrication, and test of a steel spar wind turbine blade (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The design and fabrication of wind turbine blades based on 60 foot steel spars are discussed. Performance and blade load information is given and compared to analytical prediction. In addition, performance is compared to that of the original MOD-O aluminum blades. Costs for building the two blades are given, and a projection is made for the cost in mass production. Design improvements to reduce weight and improve fatigue life are suggested.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Large Wind Turbine Design Characteristics and R and D Requirements; p 267-284
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