Power conditioning equipment for a thermoelectric outer planet spacecraft Quarterly technical report
Switching circuit, bypass, and power conditioning circuit tests for TOPS electrical system
Andrews, R.↗
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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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Design of microstrip components by computer
Development of computer programs for component analysis and design aids used in production of microstrip components is discussed. System includes designs for couplers, filters, circulators, transformers, power splitters, diode switches, and attenuators.
Cisco, T. C.↗
Active-standby servovalue/actuator development
A redundant, fail/operate fail/fixed servoactuator was constructed and tested along with electronic models of a servovalve. It was found that a torque motor switch is satisfactory for the space shuttle main engine hydraulic actuation system, and that this system provides an effective failure monitoring technique.
Masm, R. K.↗
Power conversion in electrical networks
Aspects of dc to dc conversion were studied in terms of a class of switching voltage regulators from a stability viewpoint. Background concepts of nonlinear system theory were considered, including the problem of obtaining suitable realizations for a class of positive operators. It is shown that the state evolution equations for a power conversion network are in general of bilinear form, and that the theory of lie groups and lie algebras is useful in analyzing such systems. The feedback stabilization of a class of bilinear systems whose state space is a manifold is also discussed.
Wood, J. R.↗
Inexpensive solid-state monitoring circuit
Circuit reduces intermittent fan-flutter openings in airflow switch. Circuit ignores brief switch openings due to contact oscillations; however, if switch is open longer than selected interval, control circuit shuts down system and sounds alarm.
Hardy, D. H.↗
Switchbox for welding torches
Switchbox can be used to change from one welding torch setup to another without stopping production line. Simple flip of switch connects gas, water, and power to selected torch. In conventional systems, production must be stopped so that maintenance people can disconnect and reconnect another torch.
Burley, R. K.↗
Near-term hybrid vehicle program, phase 1. Appendix B: Design trade-off studies
The relative attractiveness of various hybrid/electric power train configurations and electrical and mechanical drive-line components was studied. The initial screening was concerned primarily with total vehicle weight and economic factors and identified the hybrid power train combinations which warranted detailed evaluation over various driving cycles. This was done using a second-by-second vehicle simulation program which permitted the calculations of fuel economy, electricity usage, and emissions as a function of distance traveled in urban and highway driving. Power train arrangement possibilities were examined in terms of their effect on vehicle handling, safety, serviceability, and passenger comfort. A dc electric drive system utilizing a separately excited motor with field control and battery switching was selected for the near term hybrid vehicle. Hybrid vehicle simulations showed that for the first 30 mi (the electric range of the vehicle) in urban driving, the fuel economy was 80 mpg using a gasoline engine and 100 mpg using a diesel engine. In urban driving the hybrid would save about 75% of the fuel used by the conventional vehicle and in combined urban/highway driving the fuel saving is about 50%.
Source record↗
High voltage DC switchgear development for multi-kW space power system: Aerospace technology development of three types of solid state power controllers for 200-1100VDC with current ratings of 25, 50, and 80 amperes with one type utilizing an electromechanical device
Three types of solid state power controllers (SSPC's) for high voltage, high power DC system applications were developed. The first type utilizes a SCR power switch. The second type employes an electromechanical power switch element with solid state commutation. The third type utilizes a transistor power switch. Significant accomplishments include high operating efficiencies, fault clearing, high/low temperature performance and vacuum operation.
Billings, W. W.↗
The 30/20 GHz flight experiment system, phase 2. Volume 1: Executive summary
Summary information on the final communication system design, communication payload, space vehicle, and development plan for the 30/20 GHz flight experiment will be installed on the LEASAT spacecraft which will be placed into orbit from the space shuttle cargo bay. The communication concept has two parts: a truck service and a customer premise service (CPS). The trucking system serves four spot beams which are interconnected in a satellite switched time division multiple access mode by an IF switch matrix. The CPS covers two large areas of the eastern United States with a pair of scanning beams.
Bronstein, L.↗
Design study of a high power rotary transformer
A design study was made on a rotary transformer for transferring electrical power across a rotating spacecraft interface. The analysis was performed for a 100 KW, 20 KHz unit having a ""pancake'' geometry. The rotary transformer had a radial (vertical) gap and consisted of 4-25 KW modules. It was assumed that the power conditioning comprised of a Schwarz resonant circuit with a 20 KHz switching frequency. The rotary transformer, mechanical and structural design, heat rejection system and drive mechanism which provide a complete power transfer device were examined. The rotary transformer losses, efficiency, weight and size were compared with an axial (axial symmetric) gap transformer having the same performance requirements and input characteristics which was designed as part of a previous program. The ""pancake'' geometry results in a heavier rotary transformer primarily because of inefficient use of the core material. It is shown that the radial gap rotary transformer is a feasible approach for the transfer of electrical power across a rotating interface and can be implemented using presently available technology.
Weinberger, S. M.↗
Atmospheric attenuation for correlated satellite communication ground sites
Link margin estimates are calculated for 30/20 GHz satellite communication systems employing closely-spaced (4 to 100 km) 'dual diversity' switched ground sites. The link margin estimates are based on a new analysis in which the bivariate rain attenuation density function for two correlated ground sites is modelled by an exponential density function. The results of the exponential density function analysis enable derivation of a direct relation between rain margin estimates and probability of exceedance (link availability). Margins typically in the range 2 to 12 dB are calculated for various ground site separations and summarized for seven city locations and five satellite orbit positions over the U.S. The results can be easily extended to other EHF satellite frequencies and other locations.
Christopher, P.↗
Evaluation of restraint system concepts for the Japanese Experiment Module flight demonstration
The current International Space Station configuration includes a Japanese Experiment Module which relies on a large manipulator and a smaller dexterous manipulator to operate outside the pressurized environment of the experiment module. The module's flight demonstration is a payload that will be mounted in the aft flight deck on STS-87 to evaluate a prototype of the dexterous manipulator. Since the payload operations entail two 8-hour scenarios on consecutive days, adequate operator restraint at the workstation will be critical to the perceived success or failure of the payload. Simulations in reduced gravity environment on the KC-135A were the only way to evaluate the restraint systems and workstation configuration. Two astronaut and two non-astronaut operators evaluated the Advanced Lower Body Extremities Restraint Test and a foot loop restraint system by performing representative tasks at the workstation in each of the two restraint systems; at the end of each flight they gave their impressions of each system and the workstation. Results indicated that access to the workstation switch panels was difficult and manipulation of the hand controllers forced operators too low for optimal viewing of the aft flight deck monitors. The workstation panel should be angled for better visibility, and infrequently used switches should be on the aft flight deck panel. Pitch angle and placement of the hand controllers should optimize the operator's eye position with respect to the monitors. The lower body restraint was preferred over the foot loops because it allowed operators to maintain a more relaxed posture during long-duration tasks, its height adjustability allowed better viewing of aft flight deck monitors, and it provided better restraint for reacting forces imparted on the operator at the workstation. The foot loops provide adequate restraint for the flight demonstration tasks identified. Since results will impact the design of the workstation, both restraints should be flown and used during operation of the flight demonstration payload to evaluate the effect of restraint during long-duration tasks.
Sampaio, Carlos E.↗
Better Gas-Gap Thermal Switches For Sorption Compressors
Gas-gap thermal switches associated with sorption compressors of some heat pumps and cryogenic systems designed for higher performance, according to proposal, by introducing controlled turbulent flows into gas gaps. Utilizes convection in turbulent flow to transfer heat at greater rate. Design takes advantage of flow of working fluid. Working fluid also serve as heat transfer medium in gas gap.
Bhandari, Pradeep↗
Spectral Changes in Metal Halide and High-pressure Sodium Lamps Equipped with Electronic Dimming
Electronic dimming of high-intensity discharge lamps offers control of photosynthetic photon flux (PPF) but is often characterized as causing significant spectral changes. Growth chambers with 400-W metal halide (MH) and high-pressure sodium (HPS) lamps were equipped with a dimmer system using silicon-controlled rectifiers (SCR) as high-speed switches. Phase control operation turned the line power off for some period of the alternating current cycle. At full power, the electrical input to HPS and MH lamps was 480 W (root mean squared) and could be decreased to 267 W and 428 W, respectively, before the arc was extinguished. Concomitant with this decrease in input power, PPF decreased by 60% in HPS and 50% in MH. The HPS lamp has characteristic spectral peaks at 589 and 595 nm. As power to the HPS lamps was decreased, the 589-nm peak remained constant while the 595-nm peak decreased, equaling the 589-nm peak at 345-W input, and the 589-nm peak was almost absent at 270-W input. The MH lamp has a broader spectral output but also has a peak at 589 nm and another smaller peak at 545 nm. As input power to the MH lamps decreased, the peak at 589 diminished to equal the 545-nm peak. As input power approached 428 W, the 589-nm peak shifted to 570 nm. While the spectrum changed as input power was decreased in the MH and HPS lamps, the phytochrome equilibrium ratio (P(sub fr):P(sub tot)) remains unchanged for both lamp types.
Bubenheim, David L.↗
Spectral Changes in Metal Halide and High-Pressure Sodium Lamps Equipped with Electronic Dimming
Electronic dimming of high-intensity discharge lamps offers control of Photosynthetic Photon Flux (PPF) but is often characterized as causing significant spectral changes. Growth chambers with 400-W Metal Halide (MH) and High-Pressure Sodium (HPS) lamps were equipped with a dimmer system using Silicon-Controlled Rectifiers (SCR) as high-speed switches. Phase control operation turned the line power off for some period of the alternating current cycle. At full power, the electrical input to HPS and MH lamps was 480 W (root mean squared) and could be decreased to 267 W and 428 W, respectively, before the arc was extinguished. Concomitant with this decrease in input power, PPF decreased by 60% in HPS and 50% in MH. The HPS lamp has characteristic spectral peaks at 589 and 595 nm. As power to the HPS lamps was decreased, the 589-nm peak remained constant while the 595-nm peak decreased, equaling the 589-nm peak at 345-W input, and 589-nm peak was almost absent at 270-W input. The MH lamp has a broader spectral output but also has a peak at 589 nm and another smaller peak at 545 nm. As input power approached 428 W, the 589-nm peak shifted to 570 nm. While the spectrum changed as input power was decreased in the MH and HPS lamps, the phytochrome equilibrium ratio (P(sub ft):P(sub tot)) remains unchanged for both lamp types.
Bubenheim, David L.↗
Polydiacetylene as an all-optical picosecond Switch
Polydiacetylene derivative of 2-methyl-4-nitroaniline (PDAMNA) shows a picosecond switching property, which illustrated a partial all-optical picosecond NAND logic gate. The switching phenomenon was demonstrated by waveguiding two collinear beams at 633 nm and 532 nm through a hollow fiber of 50 micrometers diameter, coated from inside with a thin film of PDAMNA. A Z-scan investigations of a PDAMNA thin film on quartz substrate revealed that the switching effect was attributed to an excited state absorption in the systems. The studies also showed that the polymer suffers a photo-oxidation beyond an intensity level of 2.9 x 10(exp 6) w/square cm. The photo-oxidized film has different physical properties that are different from the original film before oxidation. The life time of both excited states before and after oxidation as well as their absorption coefficients were estimated by fitting a three level system model to the experimental results.
Abdeldayem, Hossin A.↗
The Logical Extension
The same software controlling autonomous and crew-assisted operations for the International Space Station (ISS) is enabling commercial enterprises to integrate and automate manual operations, also known as decision logic, in real time across complex and disparate networked applications, databases, servers, and other devices, all with quantifiable business benefits. Auspice Corporation, of Framingham, Massachusetts, developed the Auspice TLX (The Logical Extension) software platform to effectively mimic the human decision-making process. Auspice TLX automates operations across extended enterprise systems, where any given infrastructure can include thousands of computers, servers, switches, and modems that are connected, and therefore, dependent upon each other. The concept behind the Auspice software spawned from a computer program originally developed in 1981 by Cambridge, Massachusetts-based Draper Laboratory for simulating tasks performed by astronauts aboard the Space Shuttle. At the time, the Space Shuttle Program was dependent upon paper-based procedures for its manned space missions, which typically averaged 2 weeks in duration. As the Shuttle Program progressed, NASA began increasing the length of manned missions in preparation for a more permanent space habitat. Acknowledging the need to relinquish paper-based procedures in favor of an electronic processing format to properly monitor and manage the complexities of these longer missions, NASA realized that Draper's task simulation software could be applied to its vision of year-round space occupancy. In 1992, Draper was awarded a NASA contract to build User Interface Language software to enable autonomous operations of a multitude of functions on Space Station Freedom (the station was redesigned in 1993 and converted into the international venture known today as the ISS)
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Radiation Protection of New Lightweight Electromagnetic Interference Shielding Materials Determined
Weight savings as high as 80 percent could be achieved by simply switching from aluminum electromagnetic interference (EMI) shielding covers for spacecraft power systems to EMI covers made from intercalated graphite fiber composites. Because EMI covers typically make up about one-fifth of the power system mass, this change would decrease the mass of a spacecraft power system by more than 15 percent. Intercalated graphite fibers are made by diffusing guest atoms or molecules, such as bromine, between the carbon planes of the graphite fibers. The resulting bromine-intercalated fibers have mechanical and thermal properties nearly identical to pristine graphite fibers, but their resistivity is lower by a factor of 5, giving them better electrical conductivity than stainless steel and making these composites suitable for EMI shielding.
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