Search NASA⌕ Search

SEARCH · Search NASA

Results for “Container System”

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 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Instrumented Pneumatic-Impact Tester

Pneumatic-impact tester is small pressure chamber equipped with specimen holder and optical port. Device designed to test susceptibility of polymeric material to ignition by "pneumatic impact" in high-pressure gaseous oxygen. Used to determine differences among susceptibilities to ignition of different materials and of different batches of nominally same material proposed for use in systems containing pressurized oxygen. Also used to show characteristics of ignition and combustion.

Shelley, Richard M.↗
NASA NTRS1993

Robust controls with structured perturbations

This final report summarizes the recent results obtained by the principal investigator and his coworkers on the robust stability and control of systems containing parametric uncertainty. The starting point is a generalization of Kharitonov's theorem obtained in 1989, and its generalization to the multilinear case, the singling out of extremal stability subsets, and other ramifications now constitutes an extensive and coherent theory of robust parametric stability that is summarized in the results contained here.

Keel, Leehyun↗
NASA NTRS1992

The structure of particle cloud premixed flames

The structure of premixed flames propagating in combustible systems containing uniformly distributed volatile fuel particles in an oxidizing gas mixture is analyzed. This analysis is motivated by experiments conducted at NASA Lewis Research Center on the structure of flames propagating in combustible mixtures of lycopodium particles and air. Several interesting modes of flame propagation were observed in these experiments depending on the number density and the initial size of the fuel particle. The experimental results show that steady flame propagation occurs even if the initial equivalence ratio of the combustible mixture based on the gaseous fuel available in the particles, phi sub u, is substantially larger than unity. A model is developed to explain these experimental observations. In the model, it is presumed that the fuel particles vaporize first to yield a gaseous fuel of known chemical composition which then reacts with oxygen in a one-step overall process. The activation energy of the chemical reaction is presumed to be large. The activation energy characterizing the kinetics of vaporization is also presumed to be large. The equations governing the structure of the flame were integrated numerically. It is shown that the interplay of vaporization kinetics and oxidation process can result in steady flame propagation in combustible mixtures where the value of phi sub u is substantially larger than unity. This prediction is in agreement with experimental observations.

Seshadri, K.↗
NASA NTRS1993

Miniature modular microwave end-to-end receiver

An end-to-end microwave receiver system contained in a single miniature hybrid package mounted on a single heatsink is presented. It includes an input end connected to a microwave receiver antenna and an output end which produces a digital count proportional to the amplitude of a signal of a selected microwave frequency band received at the antenna and corresponding to one of the water vapor absorption lines near frequencies of 20 GHz or 30 GHz. The hybrid package is on the order of several centimeters in length and a few centimeters in height and width. The package includes an L-shaped carrier having a base surface, a vertical wall extending up from the base surface and forming a corner therewith, and connection pins extending through the vertical wall. Modular blocks rest on the base surface against the vertical wall and support microwave monolithic integrated circuits on top surfaces thereof connected to the external connection pins. The modular blocks lie end-to-end on the base surface so as to be modularly removable by sliding along the base surface beneath the external connection pins away from the vertical wall.

Sukamto, Lin M.↗
NASA NTRS1993

Premixed flame propagation in combustible particle cloud mixtures

The structures of premixed flames propagating in combustible systems, containing uniformly distributed volatile fuel particles, in an oxidizing gas mixtures is analyzed. The experimental results show that steady flame propagation occurs even if the initial equivalence ratio of the combustible mixture based on the gaseous fuel available in the particles, phi(u) is substantially larger than unity. A model is developed to explain these experimental observations. In the model it is presumed that the fuel particles vaporize first to yield a gaseous fuel of known chemical composition which then reacts with oxygen in a one-step overall process. It is shown that the interplay of vaporization kinetics and oxidation process, can result in steady flame propagation in combustible mixtures where the value of phi(u) is substantially larger than unity. This prediction is in agreement with experimental observations.

Seshadri, K.↗
NASA NTRS1992

Aquatic biofilms and their responses to disinfection and invading species

The control of microbial contamination is a primary concern in the development of a water reclamation system for long-duration manned space flights. This paper describes bench-scale experiments, using both static and recycling water systems, investigating the interaction of bacterial species in the development of a biofilm and their response to the introduction of a disinfectant or of additional species. The results showed that iodine concentrations as high as 15 to 20 mg/l I2 are necessary to completely disinfect a stable biofilm. When S. aueus and E. coli were introduced into a system containing natural mixed culture biofilms, their colonization in the biofilms increased their survival time, from 3 to 5 days as unattached cells to over 60 days when protected in the biofilms. While iodine concentrations of 0.5 to 1 mg/l were enough to eliminate these organisms from the bulk water, concentrations higher than 4.0 mg/l were necessary to completely eliminate these organisms from the biofilm.

Smithers, G. A.↗
NASA NTRS1992

Robust stability and control of linear and multilinear interval systems

This paper is a survey of recent results obtained by the authors and their coworkers on the robust stability and control of systems containing parametric uncertainty. The starting point is a generalization of Kharitonov's theorem obtained by Chapellat and Bhattacharyya in 1989. This theorem, called the Linear CB theorem, its generalization to the multilinear case, the singling out of extremal stability subsets, and other ramifications now constitute an extensive and coherent theory of robust parametric stability that is summarized in the results contained here.

Bhattacharyya, S. P.↗
NASA NTRS1994

Carbon in Comet Halley dust particles

Comets are small bodies of the solar system containing primarily a mixture of frozen gases and carbonaceous and mineral grains. They are likely to preserve volatile mineral from cold regions of the protosolar nebula and remnants of interstellar dust and gas. More than 2500 mass spectra of cometary grains with masses in the range 5 x 10 exp -17 to 5 x 10 exp -12 g were measured in situ by PUMA1 and PUMA2 mass spectrometers on board the VEGA spacecraft during flyby missions to Comet Halley. In this paper, we discuss different organic and inorganic C-containing components discovered so far in Comet Halley dust particles, the nature and abundance of which provide information about possible astrophysical sources of C and constrain models of interstellar grains.

Fomenkova, M. N.↗
NASA NTRS1994

The impact of emissions from space transport systems on the state of the atmosphere

The exhaust products of space transport systems contain many substances, some of which can lead to ozone destruction. Significant changes in atmospheric constituents were calculated in a local area within a few kilometers of the exhaust trail of rockets (i.e., over 80% decreases in local ozone), although these effects are simulated to last only a few hours. Relatively small changes in atmospheric constituents are computed for regional areas within 1000 km of the exhaust trail (i.e. less than 10% decreases in column ozone), and even smaller changes are computed on a global scale (i.e., less than 0.03% decreases in total global ozone depletion).

Jackman, Charles H.↗
NASA NTRS1995

Summary of OARE flight calibration measurements

To date, the Orbital Acceleration Research Experiment (OARE) has flown on the shuttle orbiter for five missions; namely, STS-40, STS-50, STS-58, STS-62, and STS-65. The OARE instrument system contains a three-axis accelerometer which can resolve accelerations to the nano-g (10(exp -9) g) level and a full calibration station to permit in situ bias and scale factor calibration measurements. This calibration capability eliminates the large uncertainty encountered with accelerometers flown in the past on the orbiter which use ground-based calibrations to provide absolute acceleration measurements. A detailed flight data report presentation is given for the OARE calibration measurements from all missions, along with an estimate of the calibration errors. The main aim is to collect, process, and present the calibration data in one archival report. These calibration data are the necessary key ingredient to produce the absolute acceleration levels from the OARE acceleration flight data.

Blanchard, Robert C.↗
NASA NTRS1994

The unified lunar control network: 1994 version

The objective of the unified lunar control network is to combine a series of control networks into one compatible network with its origin at the center of mass of the Moon and its coordinates referred to the mean Earth/polar axis system. The initial unified system contained 130 nearside points from Apollo data and 1026 from telescopic data. It also contained ten Mariner 10 points. The total number of points was 1166. The current network includes modifications to the past network and extends the coverage. Coordinates of points north of the Apollo region have been recomputed based on Galileo images from the second Earth-Moon flyby. Coordinates of points in the Apollo region were held fixed; however, coordinates of points north of the Apollo region in the telescopic region and many Mariner 10 points were recomputed. All of the Mariner 10 points were remeasured and integrated into the network. Additional points in the Apollo region including the farside have been added. The unified network now contains 1478 points. Apollo, Mariner 10, and Galileo pictures all contained some farside points. The coordinates of the 1478 points are available only in the microfiche supplement to this paper.

Davies, Merton E.↗
NASA NTRS1995

HST UV observations of the accretion disk corona X-ray binary X1822-371

The Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) has provided the first ultraviolet orbital light curve of the low-mass X-ray binary X1822-371. The shape of the UV light curve changes with wavelength providing the first direct clues to the temperature of the various system components. The data support the idea that the system contains a thick, structured accretion disk.

Puchnarewicz, E. M.↗
NASA NTRS1995

Beam-Steering Subsystem For Laser Communication

Proposed free-space laser communication system contains fewer optical and mechanical components. Involves novel fast beam-steering subsystem stabilizing only angle between transmitting and receiving beams instead of stabilizing both transmitting and receiving lines of sight individually. Received and transmitted beams of light both imaged onto CCD array at focal plane. Relative angular positions of beams computed from centroids of their images.

Lesh, James R.↗
NASA NTRS1995

Explorer Program: X-ray Timing Explorer

This booklet describes the X-ray Timing Explorer (XTE), one in a series of Explorer missions administered by the National Aeronautics and Space Administration's (NASA) Office of Space Science and managed by the NASA Goddard Space Flight Center (GSFC). The X-ray astronomy observatory is scheduled for launch into low-Earth orbit by Delta 2 expendable launch vehicle in late summer of 1995. The mission is expected to operate for at least 2 years and will carry out in-depth timing and spectral studies of the X-ray sources in the 2 to 200 kilo-electron Volt (keV) range. XTE is intended to study the temporal and broad-band spectral phenomena associated with stellar and galactic systems containing compact objects, including neutron stars, white dwarfs, and black holes.

Source record↗
NASA NTRS1996

Modified-Signed-Digit Optical Computing Using Fan-Out

Experimental optical computing system containing optical fan-out elements implements modified signed-digit (MSD) arithmetic and logic. In comparison with previous optical implementations of MSD arithmetic, this one characterized by larger throughput, greater flexibility, and simpler optics.

Liu, Hua-Kuang↗
NASA NTRS1996

Description of Proposed Revision of Handbook on: Propagation Effects for Land Mobile Satellite Systems

The original Handbook on Propagation Effects for Land Mobile Satellite Systems contains only referenced material through 1991. This paper describes a proposed revision to the Handbook based on some pertinent mobile satellite experiments performed and modeling results obtained since 1991. A suggested title is proposed and a summary of the type of new material to be included in the revised text is given.

Goldhirsh, Julius↗
NASA NTRS1996

Transient Accretion Events in Herbig Ae/Be Star Spectra: The Evidence for Infalling Planetesimals in HD 100546 (B9E)

Enhanced gaseous absorption resembling the high velocity circumstellar gas features in the spectrum of Beta Pic have been detected in IUE high dispersion spectra of the 2 Myr-old Herbig Be star, HD 100546, on 1995 March 9. The presence of atomic gas features in transitions of C I and O I implies that the material is produced by the pyrolysis of an unseen, solid body in a star-grazing orbit. The presence of weak Fe II absorption in the same spectrum with heavily saturated magnesium, aluminum, and silicon features is consistent with an origin in the sublimation of the olivenes detected in IRAS LRS and ISO SWS spectra of this star. The C I and O I detections suggest that, compared to Beta Pic, the planetesimals in this system contain substantial amounts of carbonaceous material. The presence of mildly refractory species such as Zn II and S II suggests that the planetesimal had not been substantially heated above 700 K during its previous lifetime.

Grady, C. A.↗
NASA NTRS1997

Hard X-ray spectra of neutron stars and black hole candidates

The hard X-ray behavior of several X-ray binary systems containing a neutron star or a black hole candidate is analyzed in an attempt to determine the specific signature of these categories of compact objects. Limiting the consideration to two subclasses of neutron stars, Atoll sources and non-pulsating Z sources, it appears that only the Atoll sources have a spectral behavior similar to black holes. It is proposed that Atoll sources are weakly magnetized neutron stars, whereas Z sources are small radius moderate magnetized neutron stars. Large magnetic fields funnel the accreting matter, thus preventing spherical accretion and free fall if the neutron star radius is smaller than the last stable accreting orbit. Weak magnetic fields do not have this effect, and blackbody soft photons from the stellar surface are upscattered on the relativistic infalling matter, leading to excess hard X-rays. This excess is visible in two of the observed Atoll sources and in the spectrum of a black hole candidate. In the case of a Z source, a lack of photons was remarked, providing a possible signature to distinguish between these classes of objects.

Durouchoux, P.↗