Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “J Division”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Crew Survivability After a Rapid Cabin Depressurization Event

Anecdotal evidence acquired through historic failure investigations involving rapid cabin decompression (e.g. Challenger, Columbia and Soyuz 11) show that full evacuation of the cabin atmosphere may occur within seconds. During such an event, the delta-pressure between the sealed suit ventilation system and the cabin will rise at the rate of the cabin depressurization; potentially at a rate exceeding the capability of the suit relief valve. It is possible that permanent damage to the suit pressure enclosure and ventilation loop components may occur as the integrated system may be subjected to delta pressures in excess of the design to pressures. Additionally, as the total pressure of the suit ventilation system decreases, so does the oxygen available to the crew. The crew may be subjected to a temporary incapacitating, but non-lethal, hypoxic environment. It is expected that the suit will maintain a survivable atmosphere on the crew until the vehicle pressure control system recovers or the cabin has otherwise attained a habitable environment. A common finding from the aforementioned reports indicates that the crew would have had a better chance at surviving the event had they been in a protective configuration, that is, in a survival suit. Making use of these lessons learned, the Constellation Program implemented a suit loop in the spacecraft design and required that the crew be in a protective configuration, that is suited with gloves on and visors down, during dynamic phases of flight that pose the greatest risk for a rapid and uncontrolled cabin depressurization event: ascent, entry, and docking. This paper details the evaluation performed to derive suit pressure garment and ventilation system performance parameters that would lead to the highest probability of crew survivability after an uncontrolled crew cabin depressurization event while remaining in the realm of practicality for suit design. This evaluation involved: (1) assessment of stakeholder expectations to validate the functionality being imposed; (2) review/refinement of concept of operations to establish the potential triggers for such an event and define the response of the spacecraft and suit ventilation loop pressure control systems; and (3) assessment of system capabilities with respect to structural capability and pressure control. 1 Crew and Thermal Systems Division, NASA Johnson Space Center, Mail Code: AES29, 2101 NASA Parkway, Houston,

Sargusingh, Miriam J.↗
NASA NTRS1990

MHD shocks in the ISM

Researchers survey shock solutions of a partially ionized gas with a magnetic field. The gas is modeled by interacting neutral, ion, electron and charged grain components. They employ a small neutral-ion chemical network to follow the dissociation and ionization of the major species. Cooling by molecular hydrogen (rotational, vibrational and dissociation), grains and dipole molecules is included. There are three basic types of solutions (C, C asterisk, and J) and some more complicated flows involving combinations of the basic types. The initial preshock conditions cover hydrogen nuclei densities of 1 less than n less than 10(exp 10) cm(-3) and shock velocities of 5 less than v(sub s) less than 60 km/s. The magnetic field is varied over 5 decades and the sensitivity of the results to grain parameters, UV and cosmic ray fluxes is ascertained. The parameter space is quite complicated, but there exist some simple divisions. When the initial ionization fraction is small (chi sub i less than 10(-5)), there is a sharp transition between fully C solutions at low velocity and strong J solutions at high velocity. When the initial ionization fraction is larger, C asterisk and/or very weak J shocks are present at low velocities in addition to the C solutions. The flow again changes to strong J shocks at high velocities. When the ionization fraction is large and the flow is only slightly greater than the bulk Alfven velocity, there is a complicated mixture of C, C asterisk and J solutions.

Chernoff, D. F.↗
NASA NTRS1973

Environmental study of ERTS-1 imagery: Lake Champlain and Vermont

Environmental concerns of the State of Vermont currently being stressed include water quality in Lake Champlain and a state-wide land use and capability plan. Significant results obtained from ERTS-1 relate directly to the above concerns. Industrial water pollution and turbidity in Lake Champlain have been identified and mapped and the ERTS pollution data will be used in the developing court suit which Vermont has initiated against the polluters. ERTS imagery has also provided a foundation for updating and revising land use inventories. Major classes of land use have been identified and mapped, and substantial progress has been made toward the mapping of such land use divisions as crop and forest type, and wetlands.

Lind, A. O.↗
NASA NTRS1988

Lunar and planetary studies

This grant supports the core program in planetary astronomy at Caltech. The research includes observations in the IR, sub-mm, mm and cm wavelengths at national and Caltech observatories with a strong emphasis on integrating the observations with spacecraft data and with models of atmospheric structure, dynamics and chemistry. Muhleman's group made extensive observations of Saturn, Uranus and Neptune which are being interpreted in terms of deep atmospheric structures which are obvious in the 2 and 6 cm maps of Saturn and Uranus. The microwave measurements are one of the few sources of information below the 2 bar level. Goldreich is investigating the dynamics of narrow rings with postdoctoral fellow, Pierre-Yves Longaretti. Their work has focused on the role of collisional stresses on the precession of the rings, since the Voyager radio science results imply that the previous model based on the ring's self-gravity is not the entire story. In addition Borderies, Goldreich and Tremaine have completed an investigation of the dynamics of the Encke division in Saturn's A ring.

Muhleman, Duane O.↗
NASA NTRS1977

Neutron monitoring and electrode calorimetry experiments in the HIP-1 Hot Ion Plasma

Results are presented for two diagnostic procedures on HIP-1: neutron diagnostics to determine where neutrons originated within the plasma discharge chamber and electrode calorimetry to measure the steady-state power absorbed by the two anodes and cathodes. Results are also reported for a hot-ion plasma formed with a continuous-cathode rod, one that spans the full length of the test section, in place of the two hollow cathodes. The outboard neutron source strength increased relative to that at the midplane when (1) the cathode tips were moved farther outboard, (2) the anode diameters were increased, and (3) one of the anodes was removed. The distribution of neutron sources within the plasma discharge chamber was insensitive to the division of current between the two cathodes. For the continuous cathode, increasing the discharge current increased the midplane neutron source strength relative to the outboard source strength. Each cathode absorbed from 12 to 15 percent of the input power regardless of the division of current between the cathodes. The anodes absorbed from 20 to 40 percent of the input power. The division of power absorption between the anodes varied with plasma operating conditions and electrode placement.

Reinmann, J. J.↗
NASA NTRS1985

Storm severity detection (RF)

Atmospheric electrical emissions occurring in association with Hurricane Alicia were observed by two crossed baseline phase linear interferometers. The sensors were located in San Antonio, Texas, and at Marshall Space Flight Center (MSFC), Huntsville, Alabama. An analysis of the data has indicated that the direction finding (DF) performance of the San Antonio site was extremely good while the DF performance at the MSFC site evidenced erratic behavior. A check of the data acquisition hardware revealed an intermitted problem in one of the radio receiver channels. Since the system has experienced several lightning strikes during the early spring of 1984, it was necessary to ship the entire rack of equipment back to SwRI for refurbishment. Analysis of the DF data from the interferometer site at San Antonio is being done. A limited subset of the MSFC data acquired during Hurricane Alicia has been found to be valid. These were data which satisfied the phase linearity criteria. Approximately 2,000 location estimates have been produced on the valid data. The results of the DF analysis and the location data are being correlated with the McIDAS data base at Marshall Space Flight Center, and with the radar summary data provided by the Hurricane Research Division using the National weather Service radar Facility at Galveston, Texas.

Johnson, R. L.↗
NASA NTRS2008

EUNIS Underflight Calibrations of CDS, EIT, TRACE, EIS, and EUVI

The Extreme-Ultraviolet Normal-Incidence Spectrograph (EUNIS) is a sounding rocket instrument that obtains imaged high-resolution solar spectra. It has now had two successful flights, on 2006 April 12 and 2007 November 16, providing data to support underflight calibrations for a number of orbiting solar experiments on both occasions. A regular part of each campaign is the end-to-end radiometric calibration of the rocket payload carried out at RAL in the UK, using the same facility that provided pre-flight CDS and EIS calibrations. The measurements, traceable to primary radiometric standards, can establish the absolute EUNIS response within a total uncertainty of 10% over its full longwave bandpass of 300-370A. During each EUNIS flight, coordinated observations are made of overlapping solar locations by all participating space experiments, and identified by subsequent image co-registrations, allowing the EUNIS calibrations to be applied to these other instruments as well. The calibration transfer is straightforward for wavelengths within the EUNIS LW bandpass, and is extended to other wavelengths by means of a series of temperature- and density-insensitive line-ratios, with one line of each pair in the calibrated band and the other in the transfer band. In this way, the EUNIS-06 flight is able to update the radiometric calibrations of CDS NISl (and 2nd-order NIS2 near 2x304A), all four channels of EIT, and the three EUV channels of TRACE. The EUNIS-07 flight will further update those missions, as well as both channels of Hinode/EIS and all four channels of STEREO/SECCHI/EUVI. Future EUNIS flights have been proposed that will continue this underflight calibration service. EUNIS is supported by the NASA Heliophysics Division through its Low Cost Access to Space Program in Solar and Heliospheric Physics.

Thomas, Roger J.↗
NASA NTRS2008

EUNIS Underflight Calibrations of CDS, EIT, TRACE, EIS, and EUVI

The Extreme-Ultraviolet Normal-Incidence Spectrograph (EUNIS) is a sounding rocket instrument that obtains imaged high-resolution solar spectra. It has now had two successful flights, on 2006 April 12 and 2007 November 16, providing data to support underflight calibrations for a number of orbiting solar experiments on both occasions. A regular part of each campaign is the end-to-end radiometric calibration of the rocket payload carried out at RAL in the UK, using the same facility that provided pre-flight CDS and EIS calibrations. The measurements, traceable to primary radiometric standards, can establish the absolute EUNIS response within a relative uncertainty of 10% over its full longwave bandpass of 300-370A. During each EUNIS flight, coordinated observations are made of overlapping solar locations by all participating space experiments, and identified by subsequent image co-registrations, allowing the EUNIS calibrations to be applied to these other instruments as well. The calibration transfer is straightforward for wavelengths within the EUNIS LW bandpass, and is extended to other wavelengths by means of a series of 'insensitive' line-ratios, with one line of each pair in the calibrated band and the other in the transfer band. In this way, the EUNIS-06 flight is able to update the radiometric calibrations of CDS NISl (plus 2nd order NIS2 near 2x304A), all four channels of EIT, and the three EUV channels of TRACE. The EUNIS-07 flight will further update those missions, as well as both channels of Hinode/EIT and all four channels of STEREO/SECCHI/EUVI. Future EUNIS flights have been proposed that will continue this underflight calibration service. EUNIS is supported by the NASA Heliophysics Division through its Low Cost Access to Space Program in Solar and Heliospheric Physics.

Thomas, Roger J.↗
NASA NTRS1976

Convective merging of vortex cores in lift-generated wakes

The several wake vortices which originate from aircraft wingtips, flap edges, engine pylons, etc. usually merge, in the far field, to form a single pair whose structure determines the hazard posed to encountering aircraft. To gain an understanding of the process whereby vortices merge and disperse, a numerical study was made of the interaction of two-dimensional, time-dependent, inviscid vortical regions. It was found that discrete boundaries, which depend on the structure and spacing of the vortices, distinguish merging from nonmerging situations. Furthermore, certain arrays of finite vortex cores that alternate in sign were found to undergo division and merging that may be useful in alleviating the hazard posed by aircraft wakes.

Rossow, V. J.↗
NASA NTRS2012

Materials Research in Microgravity 2012

Reducing gravitational effects such as thermal and solutal buoyancy enables investigation of a large range of different phenomena in materials science. The Symposium on Materials Research in Microgravity involved 6 sessions composed of 39 presentations and 14 posters with contributions from more than 14 countries. The sessions concentrated on four different categories of topics related to ongoing reduced-gravity research. Highlights from this symposium will be featured in the September 2012 issue of JOM. The TMS Materials Processing and Manufacturing Division, Process Technology and Modeling Committee and Solidification Committee sponsored the symposium.

Hyers, R.↗
NASA NTRS2001

Erythroid cell growth and differentiation in vitro in the simulated microgravity environment of the NASA rotating wall vessel bioreactor

Prolonged exposure of humans and experimental animals to the altered gravitational conditions of space flight has adverse effects on the lymphoid and erythroid hematopoietic systems. Although some information is available regarding the cellular and molecular changes in lymphocytes exposed to microgravity, little is known about the erythroid cellular changes that may underlie the reduction in erythropoiesis and resultant anemia. We now report a reduction in erythroid growth and a profound inhibition of erythropoietin (Epo)-induced differentiation in a ground-based simulated microgravity model system. Rauscher murine erythroleukemia cells were grown either in tissue culture vessels at 1 x g or in the simulated microgravity environment of the NASA-designed rotating wall vessel (RWV) bioreactor. Logarithmic growth was observed under both conditions; however, the doubling time in simulated microgravity was only one-half of that seen at 1 x g. No difference in apoptosis was detected. Induction with Epo at the initiation of the culture resulted in differentiation of approximately 25% of the cells at 1 x g, consistent with our previous observations. In contrast, induction with Epo at the initiation of simulated microgravity resulted in only one-half of this degree of differentiation. Significantly, the growth of cells in simulated microgravity for 24 h prior to Epo induction inhibited the differentiation almost completely. The results suggest that the NASA RWV bioreactor may serve as a suitable ground-based microgravity simulator to model the cellular and molecular changes in erythroid cells observed in true microgravity.

NASA Discipline Cell Biology↗