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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

An update on Lab Rover: A hospital material transporter

The development of a hospital material transporter, 'Lab Rover', is described. Conventional material transport now utilizes people power, push carts, pneumatic tubes and tracked vehicles. Hospitals are faced with enormous pressure to reduce operating costs. Cyberotics, Inc. developed an Autonomous Intelligent Vehicle (AIV). This battery operated service robot was designed specifically for health care institutions. Applications for the AIV include distribution of clinical lab samples, pharmacy drugs, administrative records, x-ray distribution, meal tray delivery, and certain emergency room applications. The first AIV was installed at Lahey Clinic in Burlington, Mass. Lab Rover was beta tested for one year and has been 'on line' for an additional 2 years.

Mattaboni, Paul↗
NASA NTRS1996

Measurements and Modeling of Soot Formation and Radiation in Microgravity Jet Diffusion Flames

This is a computational and experimental study for soot formation and radiative heat transfer in jet diffusion flames under normal gravity (1-g) and microgravity (0-g) conditions. Instantaneous soot volume fraction maps are measured using a full-field imaging absorption technique developed by the authors. A compact, self-contained drop rig is used for microgravity experiments in the 2.2-second drop tower facility at NASA Lewis Research Center. On modeling, we have coupled flame structure and soot formation models with detailed radiation transfer calculations. Favre-averaged boundary layer equations with a k-e-g turbulence model are used to predict the flow field, and a conserved scalar approach with an assumed Beta-pdf are used to predict gaseous species mole fraction. Scalar transport equations are used to describe soot volume fraction and number density distributions, with formation and oxidation terms modeled by one-step rate equations and thermophoretic effects included. An energy equation is included to couple flame structure and radiation analyses through iterations, neglecting turbulence-radiation interactions. The YIX solution for a finite cylindrical enclosure is used for radiative heat transfer calculations. The spectral absorption coefficient for soot aggregates is calculated from the Rayleigh solution using complex refractive index data from a Drude- Lorentz model. The exponential-wide-band model is used to calculate the spectral absorption coefficient for H20 and C02. It is shown that when compared to results from true spectral integration, the Rosseland mean absorption coefficient can provide reasonably accurate predictions for the type of flames studied. The soot formation model proposed by Moss, Syed, and Stewart seems to produce better fits to experimental data and more physically sound than the simpler model by Khan et al. Predicted soot volume fraction and temperature results agree well with published data for a normal gravity co-flow laminar flames and turbulent jet flames. Predicted soot volume fraction results also agree with our data for 1-g and 0-g laminar jet names as well as 1-g turbulent jet flames.

Ku, Jerry C.↗
NASA NTRS1959

Investigation of the Stability of Very Flat Spins and Analysis of Effects of Applying various Moments Utilizing the Three Moment Equations of Motion

Based on linearized equations of motion utilizing only the three moment equations and assuming only flat-spin conditions, it appears that contemporary designs (with the moment of inertia about the wing axis I(sub Y) considerably greater than the moment of inertia about the fuselage axis I(sub X) having positive values of C(sub l, sub p) (rolling-moment coefficient due to rolling) or positive values of C(sub l, sub beta) (rolling-moment coefficient due to sideslip) will probably not have a stable spin in the flat-spin region near an angle of attack of 90 deg. If the damping in pitch in flat-spin attitudes is zero, stable flat-spin conditions may not be possible on an airplane having the mass primarily distributed along the wings. The effect of moving ailerons with the spin or the effect of applying a positive pitching moment producing recovery for contemporary fighter designs will be greatest for large negative values of C(sub n, sub beta) (yawing-moment coefficient due to sideslip). In addition, for a certain critical value of positive C(sub n, sub beta), the rolling moment applied by moving ailerons with the spin or the application of a positive pitching moment will have no effect on reducing the spin rate.

Klinar, Walter J.↗
NASA NTRS1992

Stochastic gyroresonant electron acceleration in a low-beta plasma. I - Interaction with parallel transverse cold plasma waves

The gyroresonance of electrons with parallel transverse cold plasma waves is considered, and the Fokker-Planck equation describing the evolution of the electron distribution function in the presence of a spectrum of turbulence is derived. A new resonance which produces a divergence in the Fokker-Planck coefficients is identified; it results when the electron is in gyroresonance with a wave that has a group velocity equal to the velocity of the electron along the magnetic field. Under the assumption of a power-law spectral density, the Fokker-Planck coefficients are calculated numerically, and their complicated momentum and pitch-angle dependence, as well as the influence of various approximations to the dispersion relation, gyroresonance condition, and spectral density are discussed. It is found that there is no resonance gap at any pitch angle as long as the full gyroresonance condition is used and waves propagating on both directions are present.

Steinacker, Juergen↗
NASA NTRS1971

Uranium-bearing minerals of lunar rock 12013.

The U distribution in rock 12013 was studied by fission track and elemental mapping techniques. Major U-bearing phases are whitlockite, apatite, zircon, and phase beta, which is a Zr-Ti mineral rich in Fe, Nb, Y, REE, and containing up to 3.6% UO2, 4.7% ThO2 and 4.2% PbO. Calculated microprobe ages for phase beta average 4.0 b.y. and are in reasonable agreement with Rb-Sr and K-Ar ages. Phase beta plays a significant role in the U-Th-Pb systematics of rock 12012 and may play a similar role in the model ages of lunar soil.

Haines, E. L.↗
NASA NTRS1998

Chronic exposure to hypergravity affects thyrotropin-releasing hormone levels in rat brainstem and cerebellum

In studies to determine the neurochemical mechanisms underlying adaptation to altered gravity we have investigated changes in neuropeptide levels in brainstem, cerebellum, hypothalamus, striatum, hippocampus, and cerebral cortex by radioimmunoassay. Fourteen days of hypergravity (hyperG) exposure resulted in significant increases in thyrotropin-releasing hormone (TRH) content of brainstem and cerebellum, but no changes in levels of other neuropeptides (beta-endorphin, cholecystokinin, met-enkephalin, somatostatin, and substance P) examined in these areas were found, nor were TRH levels significantly changed in any other brain regions investigated. The increase in TRH in brainstem and cerebellum was not seen in animals exposed only to the rotational component of centrifugation, suggesting that this increase was elicited by the alteration in the gravitational environment. The only other neuropeptide affected by chronic hyperG exposure was met-enkephalin, which was significantly decreased in the cerebral cortex. However, this alteration in met-enkephalin was found in both hyperG and rotation control animals and thus may be due to the rotational rather than the hyperG component of centrifugation. Thus it does not appear as if there is a generalized neuropeptide response to chronic hyperG following 2 weeks of exposure. Rather, there is an increase only of TRH and that occurs only in areas of the brain known to be heavily involved with vestibular inputs and motor control (both voluntary and autonomic). These results suggest that TRH may play a role in adaptation to altered gravity as it does in adaptation to altered vestibular input following labyrinthectomy, and in cerebellar and vestibular control of locomotion, as seen in studies of ataxia.

NASA Discipline Neuroscience↗
NASA NTRS1995

Reduction, analysis, and properties of electric current systems in solar active regions

The specific attraction and, in large part, the significance of solar magnetograms lie in the fact that they give the most important data on the electric currents and the nonpotentiality of active regions. Using the vector magnetograms from the Marshall Space Flight Center (MSFC), we employ a unique technique in the area of data analysis for resolving the 180 deg ambiguity in order to calculate the spatial structure of the vertical electric current density. The 180 deg ambiguity is resolved by applying concepts from the nonlinear multivariable optimization theory. The technique is shown to be of particular importance in very nonpotential active regions. The characterization of the vertical electric current density for a set of vector magnetograms using this method then gives the spatial scale, locations, and magnitude of these current systems. The method, which employs an intermediate parametric function which covers the magnetogram and which defines the local `preferred' direction, minimizes a specific functional of the observed transverse magnetic field. The specific functional that is successful is the integral of the square of the vertical current density. We find that the vertical electric current densities have common characteristics for the extended bipolar (beta) (gamma) (delta)-regions studied. The largest current systems have j(sub z)'s which maximizes around 30 mA/sq m and have a linear decreasing distribution to a diameter of 30 Mn.

Gary, G. Allen↗
NASA NTRS1983

Electrodynamic coupling in magnetically confined stellar X-ray loops

The solar coronal complex X-ray structure is now known to involve radiation loops that coincide spatially with the magnetic loops confining the radiating plasma. An effort is presently made to identify primary submodels involved in the global coupling between a mechanical energy reservoir of beta value greater than 1 and a contiguous site of X-ray activity whose beta value is lower than 1. The 'dynamo' model invoked establishes a quantitative connection between mechanical driver properties and the dimensions, field strength, and number density distribution of elemental magnetic loops.

Ionson, J. A.↗
NASA NTRS2003

The Origin and Distribution of Heavy Elements in the CD Groups MKW 4 and AWM 4

At this point, data for MKW4 have been received and those for AWM4 are still awaited. The MKW4 data have been fully analyzed and a complete manuscript is available and in final review by co-authors before submission for refereed publication. The following is a summary of our principal findings: We examined the distribution and properties of the hot gas which makes up the group halo. The inner halo shows some signs of structure, with circular or elliptical beta-models providing a poor fit to the surface brightness profile. This may be evidence of large-scale motion in the inner halo, but we do not find evidence of sharp fronts or edges in the emission. The temperature of the halo declines in the core, with deprojected spectral fits showing a central temperature of approximately 1.3keV compared to approximately 3keV at 250 arcsec. However, cooling flow models provide poor fits to the inner regions of the group and the estimated cooling time of the gas is long except within the central dominant galaxy, NGC4073. Abundance profiles show a sharp increase in the core of the group. We conclude that MKW4 is a fairly relaxed group, which has developed a strong central temperature gradient but not a large-scale cooling flow.

Vrtilek, Jan↗
NASA NTRS2010

Finding Interstellar Particle Impacts on Stardust Aluminium Foils: The Safe Handling, Imaging, and Analysis of Samples Containing Femtogram Residues

Impact ionisation detectors on a suite of spacecraft have shown the direction, velocity, flux and mass distribution of smaller ISP entering the Solar System. During the aphelion segments of the Stardust flight, a dedicated collector surface was oriented to intercept ISP of beta = 1, and returned to Earth in January 2006. In this paper we describe the probable appeareance and size of IS particle craters from initial results of experimental impacts and numerical simulation, explain how foils are being prepared and mounted for crater searching by automated acquisition of high magnification electron images (whilst avoiding contamination of the foils) and comment on appropriate analytical techniques for Preliminary Examination (PE).

Kearsley, A. T.↗
NASA NTRS1991

Geology and tectonics of Beta Regio, Guinevere Planitia, Sedna Planitia, and Western Eistla Regio, Venus - Results from Arecibo image data

The geology of a portion of the equatorial region of Venus (1 deg S to 45 deg N and from 270 deg eastward to 30 deg) is assessed on the basis of new radar images obtained from the Arecibo Observatory. Nine geologic units are mapped on the basis of their radar characteristics, and their distribution and correspondences with topography are examined. Plains are the most abundant unit, comprising 80 percent of the area imaged, and are divided into bright, dark, and mottled. Mottled plains contain abundant lava flows and domes, suggesting that volcanism forming planes is a significant process in the equatorial region of Venus. Tesserae are found primarily on Beta Regio and its eastern flank and are interpreted to be locally stratigraphically older units, predating episodes of faulting and plains formation. On the basis of spatial and temporal relationships between geologic units, the highlands of Beta Regio and Western Eistla Regio are interpreted to have formed in association with areas of mantle upwelling which uplift plains, cause rifting, and, in the case of Beta Regio, disrupt a large region of tesserae.

Senske, D. A.↗
NASA NTRS1994

On the prediction of velocity fields from redshift space galaxy samples

We present a new method for recovering the underlying velocity field from an observed distribution of galaxies in redshift space. The method is based on a kinematic Zel'dovich relation between the velocity and density fields in redshift space. This relation is expressed in a differential equation slightly modified from the usual Poisson equation and which depends nontrivially on Beta identically equal to Omega(exp 0.6)/b. The linear equation can be readily solved by standard techniques of separation of variables by means of spherical harmonics. One can also include a term describing the 'rocket effect' discussed by Kaiser (1987). From this redshift space information alone, one can generate a prediction of the peculiar velocity field for each harmonic (l, m) as a function of distance. We note that for the quadrupole and higher order moments, the equation is a boundary value problem with solutions dependent on both the interior and exterior mass distribution. However, for a shell at distance r, the dipole, as well as the monopole, of the velocity field in the Local Group frame is fully determined by the interior mass distribution. This implies that the shear of the measured velocity field, when fitted to a dipole distortion, should be aligned and consistent with the gravity field inferred from the well determined local galaxy distribution. As a preliminary application we compute the velocity dipole of distant shells as predicted from the 1.2 Jy IRAS survey compared to the measured velocity dipole on shells, as inferred from a recent POTENT analysis. The coherence between the two fields is good, yielding a best estimate of Beta = 0.6 +/- 0.2.

Nusser, Adi↗
NASA NTRS1982

continuum and emission lines in eta Lyrae

Integral photometric characteristics of beta Lyrae were redetermined using its brightest visual companion, the star HD 174664. It was attempted to separate the fluxes coming from the two components. The flux distributions are badly contaminated by the radiation of the circumstellar hydrogen. Peculiarities seem to be present in both components; in particular, the secondary star cannot be represented by an atmosphere with a unique effective temperature, and best represented by a thick disk.

Plavec, M. J.↗
NASA NTRS1995

X-Ray Emission from the Sun in Its Youth and Old Age

We have obtained ROSAT PSPC (Roentgen Satellite Position Sensitive Proportional Counter) pointed observations of two nearby G stars of ages 70 Myr and 9.5 Gyr that are of unique importance as proxies for the Sun at the two extremes of its main-sequence evolutionary lifetime. The younger star, HD 129333 (EK Dra; G0 V), a rapid rotator with a 2.7 day period, is a strong source with an X-ray luminosity L(x)(0.2-2.4 keV) = (7.5-11.5) x 10(exp 29) erg/s. Modeling suggests a two-temperature corona with T(1) = (2.0 +/- 0.3) x 10(exp 6) K and T(2) = (9.7 +/- 0.3) x 10(exp 6) K (formal uncertainties). A continuous emission measure distribution, increasing to higher temperatures and with a cutoff at (20-30) x 10(exp 6) K, yields even better fits to the data. The old star, beta Hyi (HR 98; G2 IV), represents the Sun in the future, near the end of its hydrogen-core burning stage, when it should be rotating more slowly (present P(rot) = 25.4 day) and should have lower levels of activity. The ROSAT measurements yield L(x) = (0.9-3.0) x 10(exp 27) ergs/s and a rather cool, single coronal temperature of T = (1.7 +/- 0.4) x 10(exp 6) K. For comparison, the Sun has L(x) approx. equal to 2 x 10(exp 27) ergs/s and a coronal temperature of about T = 2 x 10(exp 6) K. These stars provide information on the decline of the stellar (and specifically solar) magnetic activity from extreme youth to old age. HD 129333 is also important in that it yields an estimate of the solar soft X-ray flux in the early solar system at the epoch of the terminal stages of planetary accretion.

Dorren, J. D.↗
DOE OSTI2026

Nb3Sn Superconducting Cavity Developments for Heavy-ion Beams

Nb3Sn has been identified as the most promising next-generation superconducting material for accelerator cavities. This is due to the higher critical temperature (Tc = 18 K) of Nb3Sn compared to niobium (Tc = 9.2 K), which leads to greatly reduced RF losses in the cavity during 4.5 K operation. This allows two important changes during cavity and cryomodule design. First, the higher Tc leads to negligible BCS losses when operated at 4.5 K, which allows for a higher frequency to be used, translating to significantly smaller cavities and cryomodules. Second, the reduced dissipated power lowers the required cryogenic cooling capacity, meaning that cavities can feasibly be operated on 5-10 W cryocoolers instead of a centralized helium refrigeration plant. These plants and distribution systems are costly and complex, requiring skilled technicians for operation and maintenance. These fundamental changes present an opportunity for a paradigm shift in how low-beta linacs are designed and operated. Fabrication and testing results of first prototypes are discussed.

Petersen, T. [Argonne]↗
DOE OSTI2023

Tailoring olefin distribution via tuning rare earth metals in bifunctional Cu-RE/beta-zeolite catalysts for ethanol upgrading

Bioethanol to middle distillate technologies have offered a unique solution to produce renewable aviation fuel for decarbonizing the hard-to-electrify sectors. Here, we have developed the series of bimetallic Cu- and rare earth-containing (RE) Beta zeolite catalysts that yield high C 3+ alkene selectivity from ethanol upgrading (>80% selectivity at ~100% conversion, 623 K). The formation rates of butene isomers to C 5+ alkenes are linearly correlated with the strength of Lewis acidic RE identity, which follows the sequence of Yb 12 /Beta >Y 7 /Beta > Gd 12 /Beta > Ce 10 /Beta > La 12 /Beta. Rate measurements indicate that the RE selection plays the vital role in altering the rate of the key competitive reactions within the ethanol-to-alkenes reaction network, namely C 4 alcohol dehydration and C-C chain growth, which dictate alkene product distributions. Finally, these findings indicate a feasible and promising method for tailoring alkene product distributions from ethanol upgrading, which is of notable significance to the generation of renewable middle distillates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Searching for New Physics in two-neutrino double beta decay with CUPID

In the past few years, attention has been drawn to the fact that a precision analysis of two-neutrino double beta decay (2υββ) allows the study of interesting physics cases like the emission of Majoron bosons and possible Lorentz symmetry violation. These processes modify the summed-energy distribution of the two electrons emitted in 2υββ. CUPID is a next-generation experiment aiming to exploit 100 Mo-enriched scintillating Li 2 MoO 4 crystals, operating as cryogenic calorimeters. Given the relatively fast half-life of 100 Mo 2υββ and the large exposure that can be reached by CUPID, we expect to measure with very high precision the 100 Mo 2υββ spectrum shape, reaching great sensitivities in the search for distortions induced by the physics beyond the Standard Model. In this contribution, we present the CUPID exclusion sensitivity for such New Physics processes, as well as the preliminary projected background of CUPID.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1982

Absolute spectrophotometry of very large redshift quasars

Absolute spectrophotometric observations of 19 quasars with redshifts greater than 2.66 are reported. Observations were made with a multichannel spectrometer covering wavelengths from 3200 to 10000 A at low resolution and allowing accurate absolute fluxes to be determined for continuum and emission lines. Analysis of energy distribution measurements indicates the continuum spectral index redward of Lyman alpha to vary from -0.2 to -1.2. Average flux levels drop by 29% between Lyman alpha and Lyman beta, and by a further 10% below Lyman beta, and a drop or change of slope occurs near the Lyman limit, all of which are attributed to absorbing clouds at different redshifts. Estimations of a covering factor of 0.08 based on the Lyman alpha and He II 1640 lines are consistent with the production of these lines by recombination. The measured emission lines are observed to have intensities proportional to the continuum flux, with the exception of C IV, which shows the luminosity effect similar to that found by Baldwin (1977).

Oke, J. B.↗