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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Accelerating Climate and Weather Simulations through Hybrid Computing

Unconventional multi- and many-core processors (e.g. IBM (R) Cell B.E.(TM) and NVIDIA (R) GPU) have emerged as effective accelerators in trial climate and weather simulations. Yet these climate and weather models typically run on parallel computers with conventional processors (e.g. Intel, AMD, and IBM) using Message Passing Interface. To address challenges involved in efficiently and easily connecting accelerators to parallel computers, we investigated using IBM's Dynamic Application Virtualization (TM) (IBM DAV) software in a prototype hybrid computing system with representative climate and weather model components. The hybrid system comprises two Intel blades and two IBM QS22 Cell B.E. blades, connected with both InfiniBand(R) (IB) and 1-Gigabit Ethernet. The system significantly accelerates a solar radiation model component by offloading compute-intensive calculations to the Cell blades. Systematic tests show that IBM DAV can seamlessly offload compute-intensive calculations from Intel blades to Cell B.E. blades in a scalable, load-balanced manner. However, noticeable communication overhead was observed, mainly due to IP over the IB protocol. Full utilization of IB Sockets Direct Protocol and the lower latency production version of IBM DAV will reduce this overhead.

hybrid computing↗
NASA NTRS1986

Measurement of Centaur/Orbiter multiple reaction forces in a full-scale test rig

A multiple component load cell for measuring load is described, and its capability and reliability are evaluated by utilizing it to measure the reaction forces between the Centaur and Centaur Support Structure. The system employs 11 six-component balances in a single test rig to react a combination of loads. The vehicle and balance loads, procedures for fabricating each balance, and the assembly of the balances are discussed. The calibration and testing of the balances are examined. It is noted that the multiple component load cell system is a cost-effective method for obtaining an accurate measurement of friction effects and primary loads.

Mole, Philip J.↗
NASA NTRS1982

T55 power turbine rotor multiplane-multispeed balancing study

A rotordynamic analysis of the T55-L-11C engine was used to evaluate the balancing needs of the power turbine and to optimize the balancing procedure. As a result, recommendations were made for implementation of a multiplane-multispeed balancing plan. Precision collars for the attachment of trial weights to a slender rotor were designed enabling demonstration balancing on production hardware. The quality of the balance was then evaluated by installing a high speed balanced power turbine in an engine and running in a test cell at the Corpus Christi Army depot. The engine used had been tested prior to the turbine changeout and showed acceptable overall vibration levels for the engine were significantly reduced, demonstrating the ability of multiplane-multispeed balancing to control engine vibration.

Martin, M. R.↗
NASA NTRS1979

Erythropoietic effects of space flight

Various factors which are important in the regulation of erythropoiesis have been studied in dehydrated mice in the belief that some information would be gained relevant to the erythropoietic effects of space flight. Dehydration reduced the plasma volume and, because changes in red cell volume were minimal, the hematocrit was elevated. Thus a state of relative erythrocytosis was produced. Understanding of the mechanism whereby these changes decreased red cell production is uncertain and appears to differ somewhat from the erythroid suppression seen following elevation of the hematocrit in animals with an absolute erythrocytosis. It is suggested that factors outside of the normal erythropoietic control pathway (such as energy balance) may play an important role in the decrease in red cell volume seen in man following space flight.

Dunn, C. D. R.↗
NASA NTRS1987

Light funnel concentrator panel for solar power

The solar concentrator design concept provides a theoretical concentration efficiency of 96 percent with power-to-weight ratios as high as 50 W/kg. Further, it eliminates the need for fragile reflective coatings and is very tolerant to pointing inaccuracies. The concept differs from conventional reflective mirrors and lens design in that is uses the principle of total internal reflection in order to funnel incident sunlight into a concentrator photovoltaic cell. The feasibility of the light funnel concentrator concept was determined through a balanced approach of analysis, development, and fabrication of prototypes, and testing of components. A three-dimensional optical model of the light funnel concentrator and photovoltaic cell was developed in order to assess the ultimate performance of such systems. In addition, a thermal and structural analysis of a typical unit was made. Techniques of fabricating the light funnel cones, optically coupling them to GaAs concentrator cells, bonding the funnels to GaAs cells, making electrical interconnects, and bonding substrates was explored and a prototype light funnel concentrator unit was fabricated and tested. Testing of the system included measurements of optical concentrating efficiency, optical concentrator to cell coupling efficiency, and electrical efficiency.

Source record↗
NASA NTRS1983

Preliminary results of the first static calibration of the RSRA helicopter active-isolator rotor balance system

The helicopter version of the Rotor Systems Research Aircraft (RSRA) is designed to make simultaneous measurements of all rotor forces and moments in flight analogous to a wind tunnel balance. Loads are measured by a combination of load cells, strain gages, and hydropneumatic active isolators which use pressure gages to measure loads. Complete evaluation of system performance required calibration of the rotor force and moment measuring system when installed in the aircraft. Measurement system responses to rotor loads obtained during the first static calibration of the RSRA helicopter are plotted and discussed. Plots of the raw transducer data are included.

Acree, C. W., Jr.↗
NASA NTRS1985

Numerical analysis of the first static calibration of the RSRA helicopter active-isolator rotor balance system

The helicopter version of the Rotor Systems Research Aircraft (RSRA) is designed to make simultaneous measurements of all rotor forces and moments in a manner analogous to a wind-tunnel balance. Loads are measured by a combination of load cells, strain gages, and hydropneumatic active isolators with built-in pressure gages. Complete evaluation of system performance requires calibration of the rotor force- and moment-measurement system when installed in the aircraft. Derivations of calibration corrections for various combinations of calibration data are discussed.

Acree, C. W., Jr.↗
NASA NTRS1984

Engineering model system study for a regenerative fuel cell: Study report

Key design issues of the regenerative fuel cell system concept were studied and a design definition of an alkaline electrolyte based engineering model system or low Earth orbit missions was completed. Definition of key design issues for a regenerative fuel cell system include gaseous reactant storage, shared heat exchangers and high pressure pumps. A power flow diagram for the 75 kW initial space station and the impact of different regenerative fuel cell modular sizes on the total 5 year to orbit weight and volume are determined. System characteristics, an isometric drawing, component sizes and mass and energy balances are determined for the 10 kW engineering model system. An open loop regenerative fuel cell concept is considered for integration of the energy storage system with the life support system of the space station. Technical problems and their solutions, pacing technologies and required developments and demonstrations for the regenerative fuel cell system are defined.

Chang, B. J.↗
NASA NTRS2009

Accelerating Climate Simulations Through Hybrid Computing

Unconventional multi-core processors (e.g., IBM Cell B/E and NYIDIDA GPU) have emerged as accelerators in climate simulation. However, climate models typically run on parallel computers with conventional processors (e.g., Intel and AMD) using MPI. Connecting accelerators to this architecture efficiently and easily becomes a critical issue. When using MPI for connection, we identified two challenges: (1) identical MPI implementation is required in both systems, and; (2) existing MPI code must be modified to accommodate the accelerators. In response, we have extended and deployed IBM Dynamic Application Virtualization (DAV) in a hybrid computing prototype system (one blade with two Intel quad-core processors, two IBM QS22 Cell blades, connected with Infiniband), allowing for seamlessly offloading compute-intensive functions to remote, heterogeneous accelerators in a scalable, load-balanced manner. Currently, a climate solar radiation model running with multiple MPI processes has been offloaded to multiple Cell blades with approx.10% network overhead.

Zhou, Shujia↗
NASA NTRS1999

Validation of Modified Wine-Rack Thermal Design for Nickel-Hydrogen Batteries in Landsat-7 Spacecraft Thermal Vacuum Test and in Flight

A heritage wine-rack thermal/mechanical design for the nickel-hydrogen batteries was the baseline at the Landsat-7 Preliminary Design Review. An integrated thermal and power analysis of the batteries performed by the author in 1994 revealed that the maximum cell-to-cell gradient was 6.6 C. The author proposed modifying the heritage wine-rack design by enhancing heat conduction from cells to cells, and from cells to battery frame. At the 1995 Intersociety Energy Conversion Engineering Conference (IECEC), the author presented a paper on methods of modifying the wine-rack design. It showed that the modified wine-rack option, which uses a metallic filler, could reduce the maximum cell-to-cell temperature gradient to 1.30 C, and could also reduce the maximum cell temperature by as much as 80 C. That design concept was adopted by the Landsat7 Project Office, and a design change was made at the Critical Design Review. Results of the spacecraft thermal vacuum and thermal balance tests, and temperature data in flight show that the temperatures of the battery cells are very uniform. The maximum cell-to-cell gradient is 1.50 C. They validate the modified wine-rack thermal design.

Choi, Michael K.↗
NASA NTRS2022

Aerospace Regenerative Fuel Cell Fluidic Component Design Challenges

A discrete regenerative fuel cell (RFC) system is currently under development at the NASA Glenn Research Center and Johnson Space Center. The objective of this activity is to produce an energy storage system with a higher specific energy (W·hr/kg) than the state-of-the-art battery technologies then test that system within an environment simulating the temperatures and pressures expected over a full lunar day cycle on the lunar surface. The system is designed to be as flight-like as possible given resource and commercially available technology limitations. The RFC system is comprised of a fuel cell power system, a high pressure electrolysis system, fluidic and electronic balance of plant systems, avionics, power management and distribution system, and software. This technical memorandum discusses components and subsystems that present challenges in developing flight ready RFCs. To remedy identified issues, functional application test plans are presented for components and subsystems primarily constructed with commercially available options due to the budget and schedule constraints of this ground technology demonstration project.

fuel cell↗
NASA NTRS1994

Climatic implications of the seasonal variation of upper troposphere water vapor

Satellite observations indicate that the humidity of the upper troposphere is higher in summer than in winter. We use general circulation model (GCM) simulations to explore the processes that maintain upper troposphere water vapor and determine its seasonal cycle. In the subtropics, drying by Hadley cell subsidence and stratiform condensation is offset primarily by moistening by eddies, with moist convection playing a minor role. Elsewhere, both mean meridional circulation and eddies moisten the upper troposphere and are balanced primarily by stratiform condensation drying. The effect of the seasonal shift of the Hadley cell is limited to latitudes equatorward of 30 deg. At higher latitudes where the largest observed summer moistening occurs, eddy moisture fluxes are primarily responsible despite the eddies being weaker in summer than winter. The same mechanism causes upper level humidity to increase in GCM climate warming simulations. The observed seasonal variation may thus be a good proxy for decadal climate change. This suggests that upper troposphere water vapor feedback is positive at all latitudes, consistent with GCM predictions.

Del Genio, Anthony D.↗
NASA NTRS1979

Recent advances in redox flow cell storage systems

Several features which were conceived and incorporated into complete redox systems that greatly enhanced its ability to be kept in proper charge balance, to be capable of internal voltage regulation, and in general be treated as a true multicell electrochemical system rather than an assembly of single cells that were wired together, were discussed. The technology status as it relates to the two application areas of solar photovoltaic/wind and distributed energy storage for electric utility applications was addressed. The cost and life advantages of redox systems were also covered.

Thaller, L. H.↗
NASA NTRS1993

Physiologic mechanisms of circulatory and body fluid losses in weightlessness identified by mathematical modeling

Central volume expansion due to fluid shifts in weightlessness is believed to activate adaptive reflexes which ultimately result in a reduction of the total circulating blood volume. However, the flight data suggests that a central volume overdistention does not persist, in which case some other factor or factors must be responsible for body fluid losses. We used a computer simulation to test the hypothesis that factors other than central volume overdistention are involved in the loss of blood volume and other body fluid volumes observed in weightlessness and in weightless simulations. Additionally, the simulation was used to identify these factors. The results predict that atrial volumes and pressures return to their prebedrest baseline values within the first day of exposure to head down tilt (HDT) as the blood volume is reduced by an elevated urine formation. They indicate that the mechanisms for large and prolonged body fluid losses in weightlessness is red cell hemoconcentration that elevates blood viscosity and peripheral resistance, thereby lowering capillary pressure. This causes a prolonged alteration of the balance of Starling forces, depressing the extracellular fluid volume until the hematocrit is returned to normal through a reduction of the red cell mass, which also allows some restoration of the plasma volume. We conclude that the red cell mass becomes the physiologic driver for a large 'undershoot' of the body fluid volumes after the normalization of atrial volumes and pressures.

Simanonok, K. E.↗
NASA NTRS2005

Production of Functional Proteins: Balance of Shear Stress and Gravity

The present invention provides for a method of culturing cells and inducing the expression of at least one gene in the cell culture. The method provides for contacting the cell with a transcription factor decoy oligonucleotide sequence directed against a nucleotide sequence encoding a shear stress response element.

Goodwin, Thomas John↗
NASA NTRS2002

Evidence for vestibular regulation of autonomic functions in a mouse genetic model

Physiological responses to changes in the gravitational field and body position, as well as symptoms of patients with anxiety-related disorders, have indicated an interrelationship between vestibular function and stress responses. However, the relative significance of cochlear and vestibular information in autonomic regulation remains unresolved because of the difficulties in distinguishing the relative contributions of other proprioceptive and interoceptive inputs, including vagal and somatic information. To investigate the role of cochlear and vestibular function in central and physiological responses, we have examined the effects of increased gravity in wild-type mice and mice lacking the POU homeodomain transcription factor Brn-3.1 (Brn-3bPou4f3). The only known phenotype of the Brn-3.1(-/-) mouse is related to hearing and balance functions, owing to the failure of cochlear and vestibular hair cells to differentiate properly. Here, we show that normal physiological responses to increased gravity (2G exposure), such as a dramatic drop in body temperature and concomitant circadian adjustment, were completely absent in Brn-3.1(-/-) mice. In line with the lack of autonomic responses, the massive increase in neuronal activity after 2G exposure normally detected in wild-type mice was virtually abolished in Brn-3.1(-/-) mice. Our results suggest that cochlear and vestibular hair cells are the primary regulators of autonomic responses to altered gravity and provide genetic evidence that these cells are sufficient to alter neural activity in regions involved in autonomic and neuroendocrine control.

Non-NASA Center↗