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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 631 records · Page 35

Solid state remote power controllers for 120 Vdc power systems

Solid state Remote Power Controllers (RPCs) developed for use in any dc power system with voltage up to 120 Vdc and distributed power up to 3.6 kW per bus are described. The RPCs were demonstrated to be reliable, 99 percent efficient, comparatively simple, and potentially low in cost. Advantages of the RPCs include: contactless switching; controlled rates of current rise and fall; current limiting; and fast, well-defined, repeatable response to overloads and faults.

Sundberg, G. R.↗

Research and Technology Objectives and Plans Summary (RTOPS)

A compilation of the summary portion of each of the Research and Technology Operating Plans (RTOP) used for management review and control of research currently in progress throughout NASA is presented along with citations and abstracts of the RTOPs. Four indexes are included: (1) subject; (2) technical monitor; (3) responsible NASA organization; and (4) RTOP number.

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Status of the Electroforming Shield Design (ESD) project

The utilization of a digital computer to augment electrodeposition/electroforming processes in which nonconducting shielding controls local cathodic current distribution is reported. The primary underlying philosophy of the physics of electrodeposition was presented. The technical approach taken to analytically simulate electrolytic tank variables was also included. A FORTRAN computer program has been developed and implemented. The program utilized finite element techniques and electrostatic theory to simulate electropotential fields and ionic transport.

Fletcher, R. E.↗

Economic consequences of improved temperature forecasts: An experiment with the Florida citrus growers (control group results). Executive summary

A demonstration experiment is being planned to show that frost and freeze prediction improvements are possible utilizing timely Synchronous Meteorological Satellite temperature measurements and that this information can affect Florida citrus grower operations and decisions so as to significantly reduce the cost for frost and freeze protection and crop losses. The design and implementation of the first phase of an economic experiment which will monitor citrus growers decisions, actions, costs and losses, and meteorological forecasts and actual weather events was carried out. The economic experiment was designed to measure the change in annual protection costs and crop losses which are the direct result of improved temperature forecasts. To estimate the benefits that may result from improved temperature forecasting capability, control and test groups were established with effective separation being accomplished temporally. The control group, utilizing current forecasting capability, was observed during the 1976-77 frost season and the results are reported. A brief overview is given of the economic experiment, the results obtained to date, and the work which still remains to be done.

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Baseline tests of the Volkswagen transporter electric delivery van

The Volkswagen Transporter, an electric delivery van, was tested as part of an Energy Research and Development Administration (ERDA) project to characterize the state of the art of electric vehicles. The Volkswagen Transporter is a standard Volkswagen van that has been converted to an electric vehicle. It is powered by a 144-volt traction battery. A direct current (dc) chopper controller, actuated by a conventional accelerator pedal, regulates the voltage or power applied to the 16-kilowatt (21-hp) motor. The braking system uses conventional hydraulic braking in combination with an electric regenerative braking system. The Volkswagen vehicle performance test results are presented.

Soltis, R. F.↗

Research and Technology Objectives and Plans Summary (RTOPS)

A compilation of the summary portions of each of the Research and Technology Operating Plans (RTOP) used for management review and control of research currently in progress throughout NASA is presented along with citations and abstracts of the RTOPs. Indexes include: subject; technical monitor; responsible NASA organization; and RTOP number.

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Open-circuit voltage improvements in low-resistivity solar cells

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.

Godlewski, M. P.↗

Alternative aircraft fuels

In connection with the anticipated impossibility to provide on a long-term basis liquid fuels derived from petroleum, an investigation has been conducted with the objective to assess the suitability of jet fuels made from oil shale and coal and to develop a data base which will allow optimization of future fuel characteristics, taking energy efficiency of manufacture and the tradeoffs in aircraft and engine design into account. The properties of future aviation fuels are examined and proposed solutions to problems of alternative fuels are discussed. Attention is given to the refining of jet fuel to current specifications, the control of fuel thermal stability, and combustor technology for use of broad specification fuels. The first solution is to continue to develop the necessary technology at the refinery to produce specification jet fuels regardless of the crude source.

Longwell, J. P.↗

Spacecraft automated operations

Trends in automation of planetary spacecraft are examined using data from missions as far back as Mariner '67 and up to the highly sophisticated Galileo. Nine design considerations which influence the degree of automation such as protection against catastrophic failures, highly repetitive functions, loss of spacecraft communications, and the need for near-real-time adaptivity are discussed. Rapid growth of automation is shown in terms of on-board hardware by plots of number of processors on board, the average speed of processors, and total core memory. The number of commands transmitted from the ground has grown to 5 million bits in Voyager, so that increases in mission complexity have increased both in spacecraft automation and ground operations. Achieving greater automation by transferring ground operations to the spacecraft with the current means of controlling missions, are considered noting proposed changes. For the future, improved computer technology, more microprocessors and increased core storage will be used, and the number of automated functions and their complexity will grow. It is concluded that using the growing computational capability of spacecraft will achieve more autonomy thus reversing the trend of increased mission complexity and cost.

Bird, T. H.↗

Power-MOSFET Voltage Regulator

Ninety-six parallel MOSFET devices with two-stage feedback circuit form a high-current dc voltage regulator that also acts as fully-on solid-state switch when fuel-cell out-put falls below regulated voltage. Ripple voltage is less than 20 mV, transient recovery time is less than 50 ms. Parallel MOSFET's act as high-current dc regulator and switch. Regulator can be used wherever large direct currents must be controlled. Can be applied to inverters, industrial furnaces photovoltaic solar generators, dc motors, and electric autos.

Miller, W. N.↗

Research and Technology Objectives and Plans Summary (RTOPS)

A compilation of the summary portions of each of the Research and Technology Objective Plans (RTOP) used for management review and control of research currently in progress throughout NASA is presented. Indexes include: subject, technical monitor, responsible NASA organization, and RTOP number.

Source record↗

Modeling and Analysis of Power Processing Systems (MAPPS). Volume 1: Technical report

Computer aided design and analysis techniques were applied to power processing equipment. Topics covered include: (1) discrete time domain analysis of switching regulators for performance analysis; (2) design optimization of power converters using augmented Lagrangian penalty function technique; (3) investigation of current-injected multiloop controlled switching regulators; and (4) application of optimization for Navy VSTOL energy power system. The generation of the mathematical models and the development and application of computer aided design techniques to solve the different mathematical models are discussed. Recommendations are made for future work that would enhance the application of the computer aided design techniques for power processing systems.

Lee, F. C.↗

Compressed television transmission: A market survey

NASA's compressed television transmission technology is described, and its potential market is considered; a market that encompasses teleconferencing, remote medical diagnosis, patient monitoring, transit station surveillance, as well as traffic management and control. In addition, current and potential television transmission systems and their costs and potential manufacturers are considered.

Lizak, R. M.↗

Research and Technology Objectives and Plans Summary (RTOPS)

A compilation of summary portions of each of the Research and Technology Objectives and Plans (RTOPS) used for management review and control of research currently in progress throughout NASA is presented. Subject, technical monitors, responsible NASA organization, and RTOP number indexes are included.

Source record↗

Fast Electronic Solar Cell Tester

Microcomputer controlled system gather current and voltage data. System consists of light source, microcomputer, programable dc power supply, analog/ digital interface, and data storage display equipment. Applies series of test loads to cell via programable dc power supply to obtain I/V characteristic curve and key cell-peformance parameter. Apparatus and programming technique are applicable to devices such as batteries and sensors.

Lathrop, J. W.↗

Portable Data Logger for Photovoltaic Panels

Instrument measures rapidly changing knee of V-I curve with extra care. Portable data logger runs on own batteries. Includes microcomputer, which controls voltage-, current-measurement increment, and solid state memory, which stores data until transferred to EPROM module. Data logger is light, compact and easily caried to remote field locations.

Cole, S. W.↗

Research and Technology Objectives and Plans (RTOP), summary

A compilation of summary portions of each of the Research and Technology Operating Plans (RTOPS) used for management review and control of research currently in progress throughout NASA is presented. Subject, technical monitor, responsible NASA organization, and RTOP number indexes are included.

Source record↗

Extinction of in-flight engine fuel-leak fires with dry chemicals

The dry chemicals discussed here are seen as having a greater weight effectiveness than the halons in current use for controlling fuel-leak fires, especially in the presence of high airflow rates. The commercial dry chemicals K2CO3, KHCO3, and KC2N2H3O3 are found to be more effective than CF2ClBr and CF3Br in delaying the hot-surface reignition of fuel-leak fires after initial extinguishment. Experimental dry chemical formulations of potassium dawsonite, KAl(OH)2CO3, and of KCl and KI are seen as being even more weight effective than the above-mentioned commercial dry chemicals. It is noted, however, that the suitability and effectiveness of dry chemicals in controlling engine nacele fires has not yet been demonstrated in test aircraft.

Altman, R. L.↗