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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 487 records · Page 27

All sources NASA NTRS DOE OSTI

NASA NTRS1979

Preliminary study, analysis and design for a power switch for digital engine actuators

Innovative control configurations using high temperature switches to operate actuator driving solenoids were studied. The impact on engine control system life cycle costs and reliability of electronic control and (ECU) heat dissipation due to power conditioning and interface drivers were addressed. Various power supply and actuation schemes were investigated, including optical signal transmission and electronics on the actuator, engine driven alternator, and inside the ECU. The use of a switching shunt power conditioner results in the most significant decrease in heat dissipation within the ECU. No overall control system reliability improvement is projected by the use of remote high temperature switches for solenoid drivers.

Beattie, E. C.↗

NASA NTRS1982

Heating of the corona and solar wind by switch-on shocks

The possibility is examined that the corona is heated by a train of weak switch-on shocks which are formed in the chromosphere from a train of Alfven waves, and which subsequently enter the corona from below. New results for the shock train propagation and dissipation and the resultant coronal heating are derived. It is shown that most of the energy in the shock train can be dissipated within one or two solar radii above the coronal base. A train of switch-on shocks therefore represents a viable coronal heating mechanism. The results are generalized to switch-on shocks in the solar wind. It is shown that such shocks can dissipate rapidly, but it is concluded that they are not the dominant factor governing the evolution of the solar wind turbulence.

Hollweg, J. V.↗

NASA NTRS1984

Solid-State Crossbar Switch

Combines analog and digital circuits for multiline/multiport switching. Bidirectional solid-state crossbar switch provides interfacing and switching for 16 X24 coordinate ports for 16 parallel signal lines. Intended for rapid manual-controlled or computer controlled reconfiguration of distributed computing systems.

Anderson, T. O.↗

NASA NTRS1983

Illuminated push-button switch

An illuminated push-button switch is described. It is characterized by the fact that is consists of a switch group, an operator button opening and closing the switch group, and a light-emitting element which illuminates the face of the operator button.

Iwagiri, T.↗

NASA NTRS1984

The 20 x 20 high speed microwave switches

Tests were conducted at NASA Lewis Research Center to characterize the proof-of-concept matrix switches built under NASA contract by Ford Aerospace and Aeronautics Corporation at Palo Alto, California, and the General Electric Company at Valley Forge, Pennsylvania. The contract requirements and goals are tabulated along with the results of the NASA tests. Characteristics examined are bandwidth, insertion loss, ripple, switching speed, isolation, standing wave ratio (input and output), deviation from linear phase, noise figure, reconfiguration rates, spurious responses, gain compression, and third order intermodulation distortion. A brief description of the testing method and a statistical analysis of the test results for each of the switches are provided.

Saunders, A.↗

NASA NTRS1983

High-speed wide band 20 x 20 microwave switch matrix

The use of a dynamic switching matrix for future communication satellites will significantly increase the communication channel capacity and improve the system capability and flexibility. This paper describes the design and development of a unique coupler crossbar 20 x 20 microwave switch matrix. This paper also presents the test results of the proof-of-concept model that meets the requirements for a high-speed satellite switched, time division multiple access (SS-TDMA) system.

Coban, E.↗

NASA NTRS1985

Remote Power Controllers For High-Power dc Switching

Circuits combine functions of remotely controlled switch and circuit breaker. Circuits developed at different power levels but conceptually very similar. Selection of appropriate switching devices and minor modifications, circuits used to build RPC's covering range of voltage and power levels limited only by switching devices chosen. RPC's using GTO's have power capability ranging from 7.8 to 52 kW, while those using MOSFET's range from 8 to 15 kW. Applications include satellite, Space Station, commerical aircraft, naval vessels, and numerous industrial areas.

Sturman, J. C.↗

NASA NTRS1986

Plug-In RF Selector Switch

Short, direct link between switch and filters reduces signal loss. New switch attaches directly to filter housing, eliminating cables and connectors. As result, losses in transmitter and receiver paths reduced by about 0.4 dB. Because connectors and cables are not used, RF path loss for selected signal through switch and filter is smaller than usual.

Hwon, A. H.↗

NASA NTRS1984

Metal vapor arc switch electromagnetic accelerator technology

A multielectrode device housed in an insulator vacuum vessel, the metal vapor vacuum switch has high power capability and can hold off voltages up to the 100 kilovolt level. Such switches can be electronically triggered and can interrupt or commutate at a zero current crossing. The physics of arc initiation, arc conduction, and interruption are examined, including material considerations; inefficiencies; arc modes; magnetic field effects; passive and forced extinction; and voltage recovery. Heating, electrode lifetime, device configuration, and external circuit configuration are discussed. The metal vapor vacuum switch is compared with SCRs, GTOs, spark gaps, ignitrons, and mechanical breakers.

Mongeau, P. P.↗

NASA NTRS1985

A new very high voltage semiconductor switch

A new family of semiconductor switches using double injection techniques and compensated deep impurities is described. They have the potential to raise switching voltages a factor of 10 higher (up to 100 kV) than p-n junction devices while exhibiting extremely low (or zero) forward voltage. Several potential power switching applications are indicated.

Sundberg, G. R.↗

NASA NTRS1985

Optical computer switching network

The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

Clymer, B.↗

NASA NTRS1985

10 kW solar array switching unit performance test results

Solar array switching unit (SASU) technology is an attractive candidate for output power regulation of solar arrays. It offers greater efficiency, lower parts count, modularity and expandability. Since the SASU has switching frequencies upwards of 15 kHz, it was necessary to determine the performance characteristics of the SASU with a real solar array and to assess the impact of long lead lengths on the switching characteristics. To accommodate these requirements, TRW developed a 10 kW, 120 volt SASU which was tested for steady state and transient resistive and converter type loadings. The results of these tests are presented and discussed in this paper.

Fleck, G. W.↗

NASA NTRS1985

A new very high voltage semiconductor switch

Sundberg, G. R.↗

NASA NTRS1987

Electronic Power Switch for Fault-Tolerant Networks

Power field-effect transistors reduce energy waste and simplify interconnections. Current switch containing power field-effect transistor (PFET) placed in series with each load in fault-tolerant power-distribution system. If system includes several loads and supplies, switches placed in series with adjacent loads and supplies. System of switches protects against overloads and losses of individual power sources.

Volp, J.↗

NASA NTRS1986

RF switch positioner for communications satellite network

The RF switch positioner is a simple, lightweight, redundant positioning mechanism used to reconfigure the antenna beam on the INTELSAT VI satellite. It simultaneously rotates approximately 100 squareax waveguide switches through a full 360 deg. The RF switch positioner has been space qualified and has performed to expectations in conjunction with the feed networks in range testing.

Storaasli, A. G.↗

NASA NTRS1987

SWITCH user's manual

The planning program, SWITCH, and its surrounding changed-goal-replanning program, Runaround, are described. The evolution of SWITCH and Runaround from an earlier planner, DEVISER, is recounted. SWITCH's plan representation, and its process of building a plan by backward chaining with strict chronological backtracking, are described. A guide for writing knowledge base files is provided, as are narrative guides for installing the program, running it, and interacting with it while it is running. Some utility functions are documented. For the sake of completeness, a narrative guide to the experimental discrepancy-replanning feature is provided. Appendices contain knowledge base files for a blocksworld domain, and a DRIBBLE file illustrating the output from, and user interaction with, the program in that domain.

Source record↗

NASA NTRS1987

Automatic antenna switching design for Extra Vehicular Activity (EVA) communication system

An Extra Vehicular Activity (EVA) crewmember had two-way communications with the space station in the Ku-band frequency (12 to 18 GHz). The maximum range of the EVA communications link with the space station is approximately one kilometer for nominal values for transmitter power, antenna gains, and receiver noise figure. The EVA Communications System, that will continue to function regardless of the astronaut's position and orientation, requires an antenna system that has full spherical coverage. Three or more antennas that can be flush mounted on the astronaut's space suit (EMU) and/or his propulsive backpack (MMU), will be needed to provide the desired coverage. As the astronaut moves in the space station, the signal received by a given EVA antenna changes. An automatic antenna switching system is needed that will switch the communication system to the antenna with the largest signal strength. A design for automatic antenna switching is presented and discussed.

Randhawa, Manjit S.↗

NASA NTRS1989

High Temperature Gas-Gap Thermal Switch

Device set to allow heat to flow across gap (switch "on") or decrease rate of transfer of heat to relatively low value (switch "off"). Operates at temperatures in approximate range of 100 to 1,500 degree C. Central cylindrical object thermally connected to (or disconnected from) environment by filling gap between inner and outer sleeves of switch (or evacuating gap) to increase (or decrease) thermal conduction across gap.

Bard, Steven↗