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1

Clumpy cold dark matter  

NASA Technical Reports Server (NTRS)

A study is conducted of cold dark matter (CDM) models in which clumpiness will inhere, using cosmic strings and textures suited to galaxy formation. CDM clumps of 10 million solar mass/cu pc density are generated at about z(eq) redshift, with a sizable fraction surviving. Observable implications encompass dark matter cores in globular clusters and in galactic nuclei. Results from terrestrial dark matter detection experiments may be affected by clumpiness in the Galactic halo.

Silk, Joseph; Stebbins, Albert

1993-01-01

2

CLUMPY STREAMS FROM CLUMPY HALOS: DETECTING MISSING SATELLITES WITH COLD STELLAR STRUCTURES  

SciTech Connect

Dynamically cold stellar streams are ideal probes of the gravitational field of the Milky Way. This paper re-examines the question of how such streams might be used to test for the presence of {sup m}issing satellites{sup -}the many thousands of dark-matter subhalos with masses 10{sup 5}-10{sup 7} M{sub sun} which are seen to orbit within Galactic-scale dark-matter halos in simulations of structure formation in {Lambda}CDM cosmologies. Analytical estimates of the frequency and energy scales of stream encounters indicate that these missing satellites should have a negligible effect on hot debris structures, such as the tails from the Sagittarius dwarf galaxy. However, long cold streams, such as the structure known as GD1 or those from the globular cluster Palomar 5 (Pal 5), are expected to suffer many tens of direct impacts from missing satellites during their lifetimes. Numerical experiments confirm that these impacts create gaps in the debris' orbital energy distribution, which will evolve into degree- and sub-degree-scale fluctuations in surface density over the age of the debris. Maps of Pal 5's own stream contain surface density fluctuations on these scales. The presence and frequency of these inhomogeneities suggests the existence of a population of missing satellites in numbers predicted in the standard {Lambda}CDM cosmologies.

Yoon, Joo Heon; Johnston, Kathryn V. [Department of Astronomy, Columbia University, New York, NY 10027 (United States); Hogg, David W., E-mail: jhyoon@astro.columbia.edu [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003 (United States)

2011-04-10

3

BayesCLUMPY: BAYESIAN INFERENCE WITH CLUMPY DUSTY TORUS MODELS  

SciTech Connect

Our aim is to present a fast and general Bayesian inference framework based on the synergy between machine learning techniques and standard sampling methods and apply it to infer the physical properties of clumpy dusty torus using infrared photometric high spatial resolution observations of active galactic nuclei. We make use of the Metropolis-Hastings Markov Chain Monte Carlo algorithm for sampling the posterior distribution function. Such distribution results from combining all a priori knowledge about the parameters of the model and the information introduced by the observations. The main difficulty resides in the fact that the model used to explain the observations is computationally demanding and the sampling is very time consuming. For this reason, we apply a set of artificial neural networks that are used to approximate and interpolate a database of models. As a consequence, models not present in the original database can be computed ensuring continuity. We focus on the application of this solution scheme to the recently developed public database of clumpy dusty torus models. The machine learning scheme used in this paper allows us to generate any model from the database using only a factor of 10{sup -4} of the original size of the database and a factor of 10{sup -3} in computing time. The posterior distribution obtained for each model parameter allows us to investigate how the observations constrain the parameters and which ones remain partially or completely undetermined, providing statistically relevant confidence intervals. As an example, the application to the nuclear region of Centaurus A shows that the optical depth of the clouds, the total number of clouds, and the radial extent of the cloud distribution zone are well constrained using only six filters. The code is freely available from the authors.

Asensio Ramos, A.; Ramos Almeida, C. [Instituto de AstrofIsica de Canarias, 38205, La Laguna, Tenerife (Spain)], E-mail: aasensio@iac.es

2009-05-10

4

High-z QSO Absorption Systems: Metal-Poor Cold Flows and Mg II Absorber Host Galaxies  

NASA Astrophysics Data System (ADS)

Cosmological simulations have suggested a new model for gas accretion in young galaxies, in which baryons flow into the star-forming disk along filamentary streams without shock heating at the dark matter halo virial radius. Observationally, these cold flows manifest as Lyman Limit Systems with low heavy element abundances. To search for cold flows in the early Universe, we have obtained echellette-resolution spectra of an HI-selected sample of LLS at z>3.5 from the Sloan Digital Sky Survey. The sightlines were selected to exhibit no heavy element absorption at the resolution afforded by SDSS, and the higher resolution data provides metallicity measurements precise enough to determine if they exhibit cold flow accretion characteristics. In a parallel program, we use the Magellan Telescopes and HST/WFC-3 to investigate the connection between Mg II absorbers and proximate galaxies at 3, extending fruitful studies of the circumgalactic medium to larger redshift.

Cooper, Thomas; Simcoe, R. A.; Cooksey, K.; O'Meara, J.

2014-01-01

5

Cold tests of HOM absorber material for the ARIEL eLINAC at TRIUMF  

NASA Astrophysics Data System (ADS)

At TRIUMF development of a 50 MeV electron accelerator is well under way. Five 1.3 GHz, superconducting 9-cell cavities will accelerate 10 mA electrons to a production target to produce rare isotopes. Each cavity will provide 10 MV accelerating voltage. Plans to upgrade the accelerator in the future to a small ring with ERL capabilities requires that the shunt impedance of the dipole higher order modes to be less than 10M? . The design of the accelerator incorporates beam line absorbers to reduce the shunt impedance of potentially dangerous dipole modes.

Kolb, P.; Laxdal, R. E.; Zvyagintsev, V.; Chao, Y. C.; Amini, B.

2014-01-01

6

Analytical Approximations for Calculating the Escape and Absorption of Radiation in Clumpy Dusty Environments  

NASA Astrophysics Data System (ADS)

We present analytical approximations for calculating the scattering, absorption, and escape of nonionizing photons from a spherically symmetric two-phase clumpy medium, with either a central point source of isotropic radiation, a uniform distribution of isotropic emitters, or uniformly illuminated by external sources. The analytical approximations are based on the mega-grains model of two-phase clumpy media, as proposed by Hobson & Padman, combined with escape and absorption probability formulae for homogeneous media. The accuracy of the approximations is examined by comparison with three-dimensional Monte Carlo simulations of radiative transfer, including multiple scattering. Our studies show that the combined mega-grains and escape/absorption probability formulae provide a good approximation of the escaping and absorbed radiation fractions for a wide range of parameters characterizing the clumpiness and optical properties of the medium. A realistic test of the analytic approximations is performed by modeling the absorption of a starlike source of radiation by interstellar dust in a clumpy medium and by calculating the resulting equilibrium dust temperatures and infrared emission spectrum of both the clumps and the interclump medium. In particular, we find that the temperature of dust in clumps is lower than in the interclump medium if the clumps are optically thick at wavelengths at which most of the absorption occurs. Comparison with Monte Carlo simulations of radiative transfer in the same environment shows that the analytic model yields a good approximation of dust temperatures and the emerging UV-FIR spectrum of radiation for all three types of source distributions mentioned above. Our analytical model provides a numerically expedient way to estimate radiative transfer in a variety of interstellar conditions and can be applied to a wide range of astrophysical environments, from clumpy star-forming regions to starburst galaxies.

Városi, Frank; Dwek, Eli

1999-09-01

7

Polarization of Dust Emission in Clumpy Molecular Clouds and Cores  

Microsoft Academic Search

Grain alignment theory has reached the stage where quantitative predictions of the degree of alignment and its variations with optical depth are possible. With the goal of studying the effect of clumpiness on submillimeter and far-infrared polarization, we have computed the polarization due to alignment via radiative torques within clumpy models of cores and molecular clouds. Our models were based

T. J. Bethell; A. Chepurnov; A. Lazarian; J. Kim

2007-01-01

8

Massive Black Hole Pairs in Clumpy, Self-gravitating Circumnuclear Disks: Stochastic Orbital Decay  

NASA Astrophysics Data System (ADS)

We study the dynamics of massive black hole pairs in clumpy gaseous circumnuclear disks. We track the orbital decay of the light, secondary black hole M •2 orbiting around the more massive primary at the center of the disk, using N-body/smoothed particle hydrodynamic simulations. We find that the gravitational interaction of M •2 with massive clumps M cl erratically perturbs the otherwise smooth orbital decay. In close encounters with massive clumps, gravitational slingshots can kick the secondary black hole out of the disk plane. The black hole moving on an inclined orbit then experiences the weaker dynamical friction of the stellar background, resulting in a longer orbital decay timescale. Interactions between clumps can also favor orbital decay when the black hole is captured by a massive clump that is segregating toward the center of the disk. The stochastic behavior of the black hole orbit emerges mainly when the ratio M •2/M cl falls below unity, with decay timescales ranging from ~1 to ~50 Myr. This suggests that describing the cold clumpy phase of the interstellar medium in self-consistent simulations of galaxy mergers, albeit so far neglected, is important to predict the black hole dynamics in galaxy merger remnants.

Fiacconi, Davide; Mayer, Lucio; Roškar, Rok; Colpi, Monica

2013-11-01

9

MASSIVE BLACK HOLE PAIRS IN CLUMPY, SELF-GRAVITATING CIRCUMNUCLEAR DISKS: STOCHASTIC ORBITAL DECAY  

SciTech Connect

We study the dynamics of massive black hole pairs in clumpy gaseous circumnuclear disks. We track the orbital decay of the light, secondary black hole M {sub .2} orbiting around the more massive primary at the center of the disk, using N-body/smoothed particle hydrodynamic simulations. We find that the gravitational interaction of M {sub .2} with massive clumps M {sub cl} erratically perturbs the otherwise smooth orbital decay. In close encounters with massive clumps, gravitational slingshots can kick the secondary black hole out of the disk plane. The black hole moving on an inclined orbit then experiences the weaker dynamical friction of the stellar background, resulting in a longer orbital decay timescale. Interactions between clumps can also favor orbital decay when the black hole is captured by a massive clump that is segregating toward the center of the disk. The stochastic behavior of the black hole orbit emerges mainly when the ratio M {sub .2}/M {sub cl} falls below unity, with decay timescales ranging from ?1 to ?50 Myr. This suggests that describing the cold clumpy phase of the interstellar medium in self-consistent simulations of galaxy mergers, albeit so far neglected, is important to predict the black hole dynamics in galaxy merger remnants.

Fiacconi, Davide; Mayer, Lucio; Roškar, Rok [Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)] [Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Colpi, Monica, E-mail: fiacconi@physik.uzh.ch [Dipartimento di Fisica 'G. Occhialini', Università di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano (Italy)] [Dipartimento di Fisica 'G. Occhialini', Università di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano (Italy)

2013-11-01

10

Simulated versus observed UV emission at high redshift: a hint for a clumpy interstellar medium?  

NASA Astrophysics Data System (ADS)

We discuss the rest-frame UV emission between 5 < z < 7 from the MareNostrum High-z Universe, an smoothed particle hydrodynamics simulation done with more than 2 billion particles. Cosmological simulations of galaxy formation generally overpredict the UV rest-frame luminosity function at high redshift, both at the bright and faint ends. In this Letter, we explore a dust attenuation model where a larger extinction is applied to star populations younger than a given age, mimicking the effect of a clumpy interstellar medium. We show that this scenario fits reasonably well both the UV luminosity functions and the UV continuum slopes derived from observations. The model assumes a large obscuration for stars younger than 25 Myr from the gas clouds where they should be embedded at their formation time. We find that the optical depth in these clouds should be between 30 and 100 times larger than the mean optical depth for the homogeneous part of the interstellar medium. These values are one order of magnitude larger than those estimated in local galaxies. Therefore, we conclude that ? cold dark matter predictions for the high-z UV emission can accommodate the current observations if we consider a dust extinction model based on the assumption of a clumpy environment at high redshift.

Forero-Romero, Jaime E.; Yepes, Gustavo; Gottlöber, Stefan; Knollmann, Steffen R.; Khalatyan, Arman; Cuesta, Antonio J.; Prada, Francisco

2010-03-01

11

The dynamical and radiative evolution of clumpy supernova ejecta  

NASA Technical Reports Server (NTRS)

Numerical simulations describing the dynamical and radiative evolution of clumpy supernova ejecta are compared with observations of optical and radio emission knots in supernova remnant (SNR) Cassiopeia A. Three major phases are identified in the evolution of clumpy ejecta: a bow-shock phase, an instability phase, and a dispersal phase. The phenomenological and radiative signatures of each phase are discussed and compared with multi-epoch measurements of small-scale features in Cas A. Good correspondence is found between theory and observations. Both support the premise that compact radio emission features are controlled more by magnetic field amplification triggered in the instability phase than by in situ acceleration of new relativistic particles.

Anderson, M. C.; Jones, T. W.; Rudnick, L.; Tregillis, I. L.; Kang, Hyesung

1994-01-01

12

Competition drives clumpy species coexistence in estuarine phytoplankton.  

PubMed

Understanding the mechanisms that maintain biodiversity is a fundamental problem in ecology. Competition is thought to reduce diversity, but hundreds of microbial aquatic primary producers species coexist and compete for a few essential resources (e.g., nutrients and light). Here, we show that resource competition is a plausible mechanism for explaining clumpy distribution on individual species volume (a proxy for the niche) of estuarine phytoplankton communities ranging from North America to South America and Europe, supporting the Emergent Neutrality hypothesis. Furthermore, such a clumpy distribution was also observed throughout the Holocene in diatoms from a sediment core. A Lotka-Volterra competition model predicted position in the niche axis and functional affiliation of dominant species within and among clumps. Results support the coexistence of functionally equivalent species in ecosystems and indicate that resource competition may be a key process to shape the size structure of estuarine phytoplankton, which in turn drives ecosystem functioning. PMID:23301158

Segura, A M; Kruk, C; Calliari, D; García-Rodriguez, F; Conde, D; Widdicombe, C E; Fort, H

2013-01-01

13

3D simulations of microquasar jets in clumpy stellar winds  

NASA Astrophysics Data System (ADS)

Context. High-mass microquasars consist of a massive star and a compact object, the latter producing jets that will interact with the stellar wind. The evolution of the jets, and ultimately their radiative outcome, could depend strongly on the inhomogeneity of the wind, which calls for a detailed study. Aims: The hydrodynamics of the interaction between a jet and a clumpy wind is studied, focusing on the global wind- and single clump-jet interplay. Methods: We have performed, using the code Ratpenat, three-dimensional numerical simulations of a clumpy wind interacting with a mildly relativistic jet, and of individual clumps penetrating into a jet. Results: For typical wind and jet velocities, filling factors of about ?0.1 are already enough for the wind to be considered as clumpy. An inhomogeneous wind makes the jet more unstable when crossing the system. Kinetic luminosities ~1037 erg/s allow the jet to reach the borders of a compact binary with an O star, as in the smooth wind case, although with a substantially higher degree of disruption. When able to enter into the jet, clumps are compressed and heated during a time of about their size divided by the sound speed in the shocked clump. Then, clumps quickly disrupt, mass-loading and slowing down the jet. Conclusions: We conclude that moderate wind clumpiness makes already a strong difference with the homogeneous wind case, enhancing jet disruption, mass-loading, bending, and likely energy dissipation in the form of emission. All this can have observational consequences at high-energies and also in the large-scale radio jets.

Perucho, M.; Bosch-Ramon, V.

2012-03-01

14

Properties of thick discs formed in clumpy galaxies  

NASA Astrophysics Data System (ADS)

We examine a possible formation scenario of galactic thick discs with numerical simulations. Thick discs have previously been argued to form in clumpy disc phase in the high-redshift Universe, which host giant clumps of ?109 M? in their highly gas-rich discs. We performed N-body/smoothed particle hydrodynamics simulations using isolated galaxy models for the purpose of verifying whether dynamical and chemical properties of the thick discs formed in such clumpy galaxies are compatible with observations. The results of our simulations seem nearly consistent with observations in dynamical properties such as radial and vertical density profiles, significant rotation velocity lag with height and distributions of orbital eccentricities. In addition, the thick discs in our simulations indicate nearly exponential dependence of ?? and ?z with radius, nearly isothermal kinematics in vertical direction and negligible metallicity gradients in radial and vertical directions. However, our simulations cannot reproduce altitudinal dependence of eccentricities, metallicity relations with eccentricities or rotation velocities, which shows striking discrepancy from recent observations of the Galactic thick disc. From this result, we infer that the clumpy disc scenario for thick-disc formation would not be suitable at least for the Milky Way. Our study, however, cannot reject this scenario for external galaxies if not all galaxies form their thick discs by the same process. In addition, we found that a significant fraction of thick-disc stars forms in giant clumps.

Inoue, Shigeki; Saitoh, Takayuki R.

2014-04-01

15

Disc formation and the origin of clumpy galaxies at high redshift  

NASA Astrophysics Data System (ADS)

Observations of high-redshift galaxies have revealed a multitude of large clumpy rapidly star-forming galaxies. Their formation scenario and their link to present-day spirals are still unknown. In this Letter, we perform adaptive mesh refinement simulations of disc formation in a cosmological context that are unrivalled in terms of mass and spatial resolution. We find that the so-called `chain-galaxies' and `clump-clusters' are a natural outcome of early epochs of enhanced gas accretion from cold dense streams as well as tidally and ram-pressured stripped material from minor mergers and satellites. Through interaction with the hot halo gas, this freshly accreted cold gas settles into a large disc-like system, not necessarily aligned to an older stellar component, that undergoes fragmentation and subsequent star formation, forming large clumps in the mass range 107-109Msolar. Galaxy formation is a complex process at this important epoch when most of the central baryons are being acquired through a range of different mechanisms - we highlight that a rapid mass loading epoch is required to fuel the fragmentation taking place in the massive arms in the outskirts of extended discs, an accretion mode that occurs naturally in the hierarchical assembly process at early epochs.

Agertz, Oscar; Teyssier, Romain; Moore, Ben

2009-07-01

16

Constraining clumpy dusty torus models using optimized filter sets  

NASA Astrophysics Data System (ADS)

Recent success in explaining several properties of the dusty torus around the central engine of active galactic nuclei has been gathered with the assumption of clumpiness. The properties of such clumpy dusty tori can be inferred by analyzing spectral energy distributions (SEDs), sometimes with scarce sampling given that large aperture telescopes and long integration times are needed to get good spatial resolution and signal. We apply the formalism of Bayesian adaptive exploration to evaluate the optimum next observation such that we maximize the constraining power of the new observed photometric point. In general, we find that the region between 10 and 200 um produces the largest increase in the expected utility, although sub-mm data from ALMA also prove to be useful. It is important to note that here we are not considering the angular resolution of the data, which is key when con- straining torus parameters. Therefore, the expected utilities derived from this methodology must be weighted with the spatial resolution of the data.

Asensio Ramos, A.; Ramos Almeida, C.

2012-12-01

17

AN OCCULTATION EVENT IN CENTAURUS A AND THE CLUMPY TORUS MODEL  

SciTech Connect

We have analyzed 16 months of sustained monitoring observations of Centaurus A from the Rossi X-Ray Timing Explorer to search for changes in the absorbing column in the line of sight to the central nucleus. We present time-resolved spectroscopy which indicates that a discrete clump of material transited the line of sight to the central illuminating source over the course of {approx}170 days between 2010 August and 2011 February with a maximum increase in the column density of about 8.4 Multiplication-Sign 10{sup 22} cm{sup -2}. This is the best quality data of such an event that has ever been analyzed with the shape of the ingress and egress clearly seen. Modeling the clump of material as roughly spherical with a linearly decreasing density profile and assuming a distance from the central nucleus commensurate with the dusty torus, we found that the clump would have a diameter of (1.4-2.4) Multiplication-Sign 10{sup 15} cm with a central number density of n{sub H} = (1.8-3.0) Multiplication-Sign 10{sup 7} cm{sup -3}. This is consistent with previous results for a similar (though possibly much longer) occultation event inferred in this source in 2003-2004 and supports models of the molecular torus as a clumpy medium.

Rivers, Elizabeth; Markowitz, Alex; Rothschild, Richard, E-mail: erivers@ucsd.edu [Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424 (United States)

2011-12-15

18

Observational constraints from supernovae Ia and gamma-ray bursts on a clumpy universe  

NASA Astrophysics Data System (ADS)

The luminosity distance describing the effect of local inhomogeneities in the propagation of light proposed by Zeldovich, Kantowski, Dyer, and Roeder is tested with two probes for two distinct ranges of redshifts: supernovae Ia in 0.015?z?1.414 and gamma-ray bursts in 1.547?z?3.57. Our analysis is performed by a Markov chain Monte Carlo code that allows us to constrain the matter density parameter ?m as well as the smoothness parameter ? that measures the inhomogeneous-homogeneous rate of the cosmic fluid in a flat ? cold dark matter model. The obtained best fits are ?m=0.285-0.018+0.019, ?=0.856-0.176+0.106 from supernovae Ia, and ?m=0.259-0.028+0.028, ?=0.587-0.202+0.201 from gamma-ray bursts, while from the joint analysis the best fits are ?m=0.284-0.020+0.021, ?=0.685-0.171+0.164 with ?red2=0.975. The value of the smoothness parameter ? indicates a clumped universe; however, it does not have an impact on the amount of dark energy (cosmological constant) needed to fit the observations. This result may be an indication that the Dyer-Roeder approximation does not describe in a precise form the effects of clumpiness in the expansion of the Universe.

Bretón, Nora; Montiel, Ariadna

2013-03-01

19

Lensing Effects on Gravitational Waves in a Clumpy Universe  

NASA Astrophysics Data System (ADS)

The distance-redshift relation via gravitational waves in the clumpy universe is simulated numerically by taking account of the effects of gravitational lensing. It is assumed that all of the matter in the universe takes the form of randomly distributed point masses, each of which has the identical mass ML. Calculations are carried out in the two extreme cases: ? ? GML/c2 and ? ? GML/c2, where ? denotes the wavelength of gravitational waves. In the former, the distance-redshift relation for the fully homogeneous and isotropic universe is reproduced with small distance dispersion, whereas, in the latter, the distance dispersion is larger. This result suggests that we might obtain the information about the typical mass of lens objects through the distance-redshift relation gleaned through observation of gravitational waves of various wavelengths.

Yoo, Chul-Moon; Nakao, Ken-Ichi; Kozaki, Hiroshi; Takahashi, Ryuichi

2008-09-01

20

Bayesclumpy: Bayesian Inference with Clumpy Dusty Torus Models  

NASA Astrophysics Data System (ADS)

Our aim is to present a fast and general Bayesian inference framework based on the synergy between machine learning techniques and standard sampling methods and apply it to infer the physical properties of clumpy dusty torus using infrared photometric high spatial resolution observations of active galactic nuclei. We make use of the Metropolis-Hastings Markov Chain Monte Carlo algorithm for sampling the posterior distribution function. Such distribution results from combining all a priori knowledge about the parameters of the model and the information introduced by the observations. The main difficulty resides in the fact that the model used to explain the observations is computationally demanding and the sampling is very time consuming. For this reason, we apply a set of artificial neural networks that are used to approximate and interpolate a database of models. As a consequence, models not present in the original database can be computed ensuring continuity. We focus on the application of this solution scheme to the recently developed public database of clumpy dusty torus models. The machine learning scheme used in this paper allows us to generate any model from the database using only a factor of 10-4 of the original size of the database and a factor of 10-3 in computing time. The posterior distribution obtained for each model parameter allows us to investigate how the observations constrain the parameters and which ones remain partially or completely undetermined, providing statistically relevant confidence intervals. As an example, the application to the nuclear region of Centaurus A shows that the optical depth of the clouds, the total number of clouds, and the radial extent of the cloud distribution zone are well constrained using only six filters. The code is freely available from the authors.

Asensio Ramos, A.; Ramos Almeida, C.

2009-05-01

21

Polarization of Dust Emission in Clumpy Molecular Clouds and Cores  

NASA Astrophysics Data System (ADS)

Grain alignment theory has reached the stage where quantitative predictions of the degree of alignment and its variations with optical depth are possible. With the goal of studying the effect of clumpiness on submillimeter and far-infrared polarization, we have computed the polarization due to alignment via radiative torques within clumpy models of cores and molecular clouds. Our models were based on a highly inhomogeneous simulation of compressible MHD turbulence. A reverse Monte Carlo radiative transfer method was used to calculate the intensity and anisotropy of the internal radiation field, and the subsequent grain alignment was computed for a power-law size distribution of grains using the DDSCAT package for radiative torques. The intensity and anisotropy of the intracloud radiation field show large variations throughout the models but are generally sufficient to drive widespread grain alignment. The P-I relations for our models reproduce those seen in observations. We show that the degree of polarization observed is extremely sensitive to the upper grain size cutoff and is less sensitive to changes in the radiative anisotropy. Furthermore, despite a variety of dust temperatures along a single line of sight through our models and among dust grains of different sizes, the assumption of isothermality among the aligned grains does not introduce a significant error. Our calculations indicate that submillimeter polarization vectors can be reasonably good tracers for the underlying magnetic field structure, even for relatively dense clouds (AV~10 to the cloud center). The current predictive power of the grain alignment theory should motivate future polarization observations using the next generation of multiwavelength submillimeter polarimeters such as those proposed for SOFIA.

Bethell, T. J.; Chepurnov, A.; Lazarian, A.; Kim, J.

2007-07-01

22

MIXING OF CLUMPY SUPERNOVA EJECTA INTO MOLECULAR CLOUDS  

SciTech Connect

Several lines of evidence, from isotopic analyses of meteorites to studies of the Sun's elemental and isotopic composition, indicate that the solar system was contaminated early in its evolution by ejecta from a nearby supernova. Previous models have invoked supernova material being injected into an extant protoplanetary disk, or isotropically expanding ejecta sweeping over a distant (>10 pc) cloud core, simultaneously enriching it and triggering its collapse. Here, we consider a new astrophysical setting: the injection of clumpy supernova ejecta, as observed in the Cassiopeia A supernova remnant, into the molecular gas at the periphery of an H II region created by the supernova's progenitor star. To track these interactions, we have conducted a suite of high-resolution (1500{sup 3} effective) three-dimensional numerical hydrodynamic simulations that follow the evolution of individual clumps as they move into molecular gas. Even at these high resolutions, our simulations do not quite achieve numerical convergence, due to the challenge of properly resolving the small-scale mixing of ejecta and molecular gas, although they do allow some robust conclusions to be drawn. Isotropically exploding ejecta do not penetrate into the molecular cloud or mix with it, but, if cooling is properly accounted for, clumpy ejecta penetrate to distances {approx}10{sup 18} cm and mix effectively with large regions of star-forming molecular gas. In fact, the {approx}2 M{sub Sun} of high-metallicity ejecta from a single core-collapse supernova is likely to mix with {approx}2 Multiplication-Sign 10{sup 4} M{sub Sun} of molecular gas material as it is collapsing. Thus, all stars forming late ( Almost-Equal-To 5 Myr) in the evolution of an H II region may be contaminated by supernova ejecta at the level {approx}10{sup -4}. This level of contamination is consistent with the abundances of short-lived radionuclides and possibly some stable isotopic shifts in the early solar system and is potentially consistent with the observed variability in stellar elemental abundances. Supernova contamination of forming planetary systems may be a common, universal process.

Pan Liubin; Desch, Steven J.; Scannapieco, Evan; Timmes, F. X. [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States)

2012-09-01

23

Absorbing Outflows in AGN  

NASA Technical Reports Server (NTRS)

The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

Mathur, Smita

2002-01-01

24

Soft versus hard X-ray emission in active galactic nuclei: partial-covering and warm-plus-cold absorber models  

NASA Astrophysics Data System (ADS)

We analyse the ROSAT Position Sensitive Proportional Counter (PSPC) hardness ratio and the 0.5-2-keV to 2-10-keV flux ratio of 65 active galactic nuclei (AGN) for which there are both ROSAT archival observations available and 2-10-keV fluxes, mostly from the HEAO-1 MC-LASS survey. We conclude that the simplest spectral model for the AGN that can accommodate the variety of X-ray colours obtained is a standard power law (with energy spectral index alpha~0.9) plus a ~0.1-keV blackbody, both of which are partially absorbed. In our sample, type 1 AGN require an absorbing column around 10^22 cm^-2 with covering fractions between 20 and 100 per cent, while type 2 AGN display larger columns and ~100 per cent coverage. This simple model also provides a good link between soft and hard AGN X-ray luminosity functions and source counts. We also consider a warm absorber as an alternative model to partial covering and find that the presence of gas in two phases (ionized and neutral) is required.

Ceballos, M. T.; Barcons, X.

1996-09-01

25

Laboratory experiments to study supersonic astrophysical flows interacting with clumpy environments  

Microsoft Academic Search

A wide variety of objects in the universe drive supersonic outflows through the interstellar medium which is often highly clumpy. These inhomogeneities affect the morphology of the shocks that are generated. The hydrodynamics is difficult to model as the problem is inherently 3D and the clumps are subject to a variety of fluid instabilities as they are accelerated and destroyed

P. A. Rosen; J. M. Foster; B. H. Wilde; R. Coker; B. E. Blue; R. J. R. Williams; F. Hansen; C. Sorce; P. Hartigan; R. Carver; J. Palmer

2008-01-01

26

Laboratory experiments to study supersonic astrophysical flows interacting with clumpy environments  

Microsoft Academic Search

A wide variety of objects in the universe drive supersonic outflows through the interstellar medium which is often highly clumpy. These inhomogeneities affect the morphology of the shocks that are generated. The hydrodynamics is difficult to model as the problem is inherently 3D and the clumps are subject to a variety of fluid instabilities as they are accelerated and destroyed

P. A. Rosen; J. M. Foster; B. H. Wilde; R. Coker; B. E. Blue; R. J. R. Williams; F. Hansen; C. Sorce; P. Hartigan; R. Carver; J. Palmer

2007-01-01

27

Wing Galaxies: A Formation Mechanism of the Clumpy Irregular Galaxy Markarian 297.  

National Technical Information Service (NTIS)

In order to contribute to an understanding of collision-induced starburst activities, the authors present a detailed case study on the starburst galaxy Markarian 297 (= NGC 6052 = Arp 209; hereafter Mrk 297). This galaxy is classified as a clumpy irregula...

Y. Taniguchi M. Noguchi

1990-01-01

28

Absorb & Repel  

NSDL National Science Digital Library

In this activity, learners investigate how different materials repel or absorb water. Learners use spray bottles to explore how everyday items like sponges, cardboard, feathers, etc. respond to water differently. This activity also introduces learners to the scientific method as learners make predictions about which materials will absorb or repel water.

Museum, Kohl C.

2012-01-01

29

First X-ray-based statistical tests for clumpy-torus models: eclipse events from 230 years of monitoring of Seyfert AGN  

NASA Astrophysics Data System (ADS)

We present an analysis of multitime-scale variability in line-of-sight X-ray-absorbing gas as a function of optical classification in a large sample of Seyfert active galactic nuclei (AGN) to derive the first X-ray statistical constraints for clumpy-torus models. We systematically search for discrete absorption events in the vast archive of Rossi X-ray Timing Explorer monitoring of dozens of nearby type I and Compton-thin type II AGN. We are sensitive to discrete absorption events due to clouds of full-covering, neutral or mildly ionized gas with columns ? 1022 - 25 cm-2 transiting the line of sight. We detect 12 eclipse events in 8 objects, roughly tripling the number previously published from this archive. Peak column densities span ˜4-26 × 1022 cm-2, i.e. there are no full-covering Compton-thick events in our sample. Event durations span hours to months. The column density profile for an eclipsing cloud in NGC 3783 is doubly spiked, possibly indicating a cloud that is being tidally sheared. We infer the clouds' distances from the black hole to span ˜0.3-140 × 104Rg. In seven objects, the clouds' distances are commensurate with the outer portions of broad line regions (BLR), or outside the BLR by factors up to ˜10 (the inner regions of infrared-emitting dusty tori). We discuss implications for cloud distributions in the context of clumpy-torus models. Eight monitored type II AGN show X-ray absorption that is consistent with being constant over time-scales from 0.6 to 8.4 yr. This can either be explained by a homogeneous medium, or by X-ray-absorbing clouds that each have NH ? 1022 cm-2. The probability of observing a source undergoing an absorption event, independent of constant absorption due to non-clumpy material, is 0.006^{+0.160}_{-0.003} for type Is and 0.110^{+0.461}_{-0.071} for type IIs.

Markowitz, A. G.; Krumpe, M.; Nikutta, R.

2014-04-01

30

An X-Ray Spectral Model for Clumpy Tori in Active Galactic Nuclei  

NASA Astrophysics Data System (ADS)

We construct an X-ray spectral model for the clumpy torus in an active galactic nucleus (AGN) using Geant4, which includes the physical processes of the photoelectric effect, Compton scattering, Rayleigh scattering, ? conversion, fluorescence line, and Auger process. Since the electrons in the torus are expected to be bounded instead of free, the deviation of the scattering cross section from the Klein-Nishina cross section has also been included, which changes the X-ray spectra by up to 25% below 10 keV. We have investigated the effect of the clumpiness parameters on the reflection spectra and the strength of the fluorescent line Fe K?. The volume filling factor of the clouds in the clumpy torus only slightly influences the reflection spectra, however, the total column density and the number of clouds along the line of sight significantly change the shapes and amplitudes of the reflection spectra. The effect of column density is similar to the case of a smooth torus, while a small number of clouds along the line of sight will smooth out the anisotropy of the reflection spectra and the fluorescent line Fe K?. The smoothing effect is mild in the low column density case (N H = 1023 cm-2), whereas it is much more evident in the high column density case (N H = 1025 cm-2). Our model provides a quantitative tool for the spectral analysis of the clumpy torus. We suggest that the joint fits of the broad band spectral energy distributions of AGNs (from X-ray to infrared) should better constrain the structure of the torus.

Liu, Yuan; Li, Xiaobo

2014-05-01

31

A Laboratory Investigation of Supersonic Clumpy Flows: Experimental Design and Theoretical Analysis  

NASA Astrophysics Data System (ADS)

We present a design for high energy density laboratory experiments studying the interaction of hypersonic shocks with a large number of inhomogeneities. These ``clumpy'' flows are relevant to a wide variety of astrophysical environments, including the evolution of molecular clouds, outflows from young stars, planetary nebulae, and active galactic nuclei. The experiment consists of a strong shock (driven by a pulsed-power machine or a high-intensity laser) impinging on a region of randomly placed plastic rods. We discuss the goals of the specific design and how they are met by specific choices of target components. An adaptive mesh refinement hydrodynamic code is used to analyze the design and establish a predictive baseline for the experiments. The simulations confirm the effectiveness of the design in terms of articulating the differences between shocks propagating through smooth and clumpy environments. In particular, we find significant differences between the shock propagation speeds in a clumpy medium and those in a smooth one with the same average density. The simulation results are of general interest for foams in both inertial confinement fusion and laboratory astrophysics studies. Our results highlight the danger of using average properties of inhomogeneous astrophysical environments when comparing timescales for critical processes, such as shock crossing and gravitational collapse.

Poludnenko, A. Y.; Dannenberg, K. K.; Drake, R. P.; Frank, A.; Knauer, J.; Meyerhofer, D. D.; Furnish, M.; Asay, J. R.; Mitran, S.

2004-03-01

32

Cold Sores  

MedlinePLUS

... directly to your desktop! more... What Are Cold Sores? Article Chapters What Are Cold Sores? Cold Sore ... 2012 Previous Next Related Articles: Canker and Cold Sores Aloe Vera May Help Relieve Mouth Sores Canker ...

33

DYNAMO - II. Coupled stellar and ionized-gas kinematics in two low-redshift clumpy discs  

NASA Astrophysics Data System (ADS)

We study the spatially resolved stellar kinematics of two star-forming galaxies at z ˜ 0.1 from the larger DYnamics of Newly Assembled Massive Objects (DYNAMO) sample. These galaxies, which have been characterized by high levels of star formation and large ionized-gas velocity dispersions, are considered possible analogues to high-redshift clumpy discs. They were observed using the Gemini Multi-Object Spectrograph instrument in integral field spectroscopy (IFS) mode at the Gemini Observatory with high spectral resolution (R ? 5400, equivalent to ? ? 24 km s-1 at the observed wavelengths) and ˜6 h exposure times in order to measure the resolved stellar kinematics via absorption lines. We also obtain higher quality emission-line kinematics than previous observations. The spatial resolution (1.2 kpc) is sufficient to show that the ionized gas in these galaxies (as traced by H? emission) is morphologically irregular, forming multiple giant clumps while stellar continuum light is smooth and well described by an exponential profile. Clumpy gas morphologies observed in IFS data are confirmed by complementary narrow-band H? imaging from the Hubble Space Telescope. Morphological differences between the stars and ionized gas are not reflected dynamically as stellar kinematics are found to be closely coupled to the kinematics of the ionized gas: both components are smoothly rotating with large velocity dispersions (˜40 km s-1) suggesting that the high gas dispersions are not primarily driven by star formation feedback. In addition, the stellar population ages of these galaxies are estimated to be quite young (60-500 Myr). The large velocity dispersions measured for these young stars suggest that we are seeing the formation of thick discs and/or stellar bulges in support of recent models which produce these from clumpy galaxies at high redshift.

Bassett, Robert; Glazebrook, Karl; Fisher, David B.; Green, Andrew W.; Wisnioski, Emily; Obreschkow, Danail; Cooper, Erin Mentuch; Abraham, Roberto G.; Damjanov, Ivana; McGregor, Peter J.

2014-08-01

34

Larson's scaling laws, and the gravitational instability of clumpy discs at high redshift  

NASA Astrophysics Data System (ADS)

Gravitational instabilities play a primary role in shaping the clumpy structure and powering the star formation activity of gas-rich high-redshift galaxies. Here, we analyse the stability of such systems, focusing on the size and mass ranges of unstable regions in the disc. Our analysis takes into account the mass-size and linewidth-size scaling relations observed in molecular gas, originally discovered by Larson. We show that such relations can have a strong impact on the size and mass of star-forming clumps, as well as on the stability properties of the disc at all observable scales, making the classical Toomre parameter a highly unreliable indicator of gravitational instability. For instance, a disc with Q = 1 can be far from marginal instability, while a disc with Q ? 1 can be marginally unstable. Our work raises an important caveat: if clumpy discs at high redshift have scale-dependent surface densities and velocity dispersions, as implied by the observed clump scaling relations, then we cannot thoroughly understand their stability and star formation properties unless we perform multiscale observations. This will soon be possible thanks to dedicated Atacama Large Millimeter/submillimeter Array surveys, which will explore the physical properties of supergiant molecular clouds at the peak of cosmic star formation and beyond.

Romeo, Alessandro B.; Agertz, Oscar

2014-08-01

35

Radiative Transfer Modeling of AGN Dusty Tori as a Clumpy Two-Phase Medium  

NASA Astrophysics Data System (ADS)

We investigated the emission of active galactic nuclei dusty tori in the infrared domain, with a focus on the 10 ?m silicate feature. We modeled the dusty torus as a clumpy two-phase medium with high-density clumps and a low-density medium filling the space between the clumps. We employed a three-dimensional radiative transfer code to obtain spectral energy distributions and images of tori at different wavelengths. We calculated a grid of models for different parameters and analyzed the influence of these parameters on the shape of the mid-infrared emission. A corresponding set of clumps-only models and models with a smooth dust distribution is calculated for comparison. We found that the dust distribution, the optical depth and a random arrangement of clumps in the innermost region, all have an impact on the shape and strength of the silicate feature. The 10 ?m silicate feature can be suppressed for some parameters, but models with smooth dust distribution are also able to produce a wide range of the silicate feature strength. Finally, we find that having the dust distributed in a two-phase medium, might offer a natural solution to the lack of emission in the near-infrared, compared to observed data, which affects clumpy models currently available in the literature.

Stalevski, M.; Fritz, J.; Baes, M.; Nakos, T.; Popovic, L. C.

2012-12-01

36

Milliarcsecond imaging of clumpy dust clouds in the red giant L2 Pup with the Very Large Telescope Interferometer  

NASA Astrophysics Data System (ADS)

Despite its importance in mass loss, the dust formation in AGB stars is not yet understood well. There is growing evidence that the dust envelopes of AGB stars are much more complex--clumpy and/or bipolar--than spherically expanding shells. The non-spherical structures emerging in AGB stars may be the seed of asymmetry in planetary nebulae. However, direct observations of the clumpy dust cloud formation close to the star is difficult, because we need milliarcsecond spatial resolution. We present milliarcsecond resolution near-IR imaging of the bright, nearby M giant L2 Pup. The 2.2 micron image taken with VLT/NACO at a spatial resolution of 54 mas shows an asymmetric circumstellar envelope with 300 x 200 mas (12 x 8 stellar radii), elongated in East-West direction. Furthermore, we succeeded in aperture-synthesis imaging of L2 Pup by combining these single-dish VLT/NACO data with near-IR interferometric data taken with the AMBER instrument at the Very Large Telescope Interferometer. The reconstructed image with a spatial resolution of 12 mas shows two clumps at 20--30 mas away from the star, as well as another clump over the stellar. This is the first imaging of clumpy dust clouds toward L2 Pup, whose presence was only inferred from polarimetric and photometric observations. Our observations reveal the clumpy dust formation close to the star, at 1.5--2.5 stellar radii.

Ohnaka, K.; Schertl, D.; Hofmann, K. H.; Weigelt, G.

2014-04-01

37

Clumpy Langmuir waves in type III radio sources - Comparison of stochastic-growth theory with observations  

NASA Technical Reports Server (NTRS)

Detailed comparisons are made between the Langmuir-wave properties predicted by the recently developed stochastic-growth theory of type III sources and those observed by the plasma wave experiment on ISEE 3, after correcting for the main instrumental and selection effects. Analysis of the observed field-strength distribution confirms the theoretically predicted form and implies that wave growth fluctuates both spatially and temporally in sign and magnitude, leading to an extremely clumpy distribution of fields. A cutoff in the field-strength distribution is seen at a few mV/m, corresponding to saturation via nonlinear effects. Analysis of the size distribution of Langmuir clumps yields results in accord with those obtained in earlier work and with the size distribution of ambient density fluctuations in the solar wind. This confirms that the inhomogeneities in the Langmuir growth rate are determined by the density fluctuations and that these fluctuations persist during type III events.

Robinson, P. A.; Cairns, I. H.; Gurnett, D. A.

1993-01-01

38

Analysis of Cold Neutron Spectra of Metals.  

National Technical Information Service (NTIS)

A recently developed method for obtaining the absorbed energy spectrum, and calculating its absorption frequencies from elastic constants data, has been applied to metals, using cold neutron spectra in absence of infrared data. The emitted spectrum from i...

H. S. Plendl R. A. Kromhout

1971-01-01

39

Perfect Metamaterial Absorber  

Microsoft Academic Search

We present the design for an absorbing metamaterial (MM) with near unity absorbance A(omega). Our structure consists of two MM resonators that couple separately to electric and magnetic fields so as to absorb all incident radiation within a single unit cell layer. We fabricate, characterize, and analyze a MM absorber with a slightly lower predicted A(omega) of 96%. Unlike conventional

N. I. Landy; S. Sajuyigbe; J. J. Mock; D. R. Smith; W. J. Padilla

2008-01-01

40

Investigating the sensitivity of observed spectral energy distributions to clumpy torus properties in Seyfert galaxies  

NASA Astrophysics Data System (ADS)

We present nuclear spectral energy distributions (SEDs) from 1 to 18 ?m of a small sample of nearby, nearly face-on and undisturbed Seyfert galaxies without prominent nuclear dust lanes. These nuclear SEDs probe the central ˜35 pc of the galaxies, on average, and include photometric and spectroscopic infrared (IR) data. We use these SEDs, the clumpy torus models of Nenkova et al. and a Bayesian approach to study the sensitivity of different IR wavelengths to the torus parameters. We find that high angular resolution 8-13 ?m spectroscopy alone reliably constrains the number of clumps and their optical depth (N0 and ?V). On the other hand, we need a combination of mid- and near-IR subarcsecond resolution photometry to constrain torus width and inclination, as well as the radial distribution of the clouds (?, i and q). For flat radial profiles (q = 0, 1), it is possible to constrain the extent of the mid-IR-emitting dust within the torus (Y) when N-band spectroscopy is available, in addition to near-IR photometry. Finally, by fitting different combinations of average and individual Seyfert 1 and Seyfert 2 data, we find that, in general, for undisturbed, nearly face-on Seyferts without prominent nuclear dust lanes, the minimum combination of data necessary to reliably constrain all the torus parameters is J+K+M-band photometry + N-band spectroscopy.

Ramos Almeida, C.; Alonso-Herrero, A.; Levenson, N. A.; Asensio Ramos, A.; Rodríguez Espinosa, J. M.; González-Martín, O.; Packham, C.; Martínez, M.

2014-04-01

41

Platelike Dynamic Vibration Absorber.  

National Technical Information Service (NTIS)

The patent application describes platelike dynamic vibration absorbers for providing vibration suppression. Optimum values of their tuning and damping are specified. The dynamic absorbers are comprised either of a circular or an annular damped plate that ...

J. C. Snowdon

1975-01-01

42

Infrared Saturable Absorber Devices.  

National Technical Information Service (NTIS)

Gaseous saturable absorbers are studied. These absorbers are used for mode-locking of infrared lasers, particularly CO2. Nonlinear-optical coefficients and transition moments were measured. Detectors for infrared radiation were also studied. Mechanisms of...

S. E. Schwarz

1975-01-01

43

Bend-absorbing clamp  

NASA Technical Reports Server (NTRS)

Compact, inexpensive clamp for flexible cables or rigid tubes absorbs vibrations and other motion. It accomodates wide range of dimensions, and saves space by eliminating pigtails or bellows commonly used to absorb linear movement or vibrations

Abbott, J. R.; Valencia, B., Jr.

1979-01-01

44

MAPPING THE CLUMPY STRUCTURES WITHIN SUBMILLIMETER GALAXIES USING LASER-GUIDE STAR ADAPTIVE OPTICS SPECTROSCOPY  

SciTech Connect

We present the first integral-field spectroscopic observations of high-redshift submillimeter-selected galaxies (SMGs) using Laser-Guide Star Adaptive Optics. We target H{alpha} emission of three SMGs at redshifts z {approx} 1.4-2.4 with the OH-Suppressing Infrared Imaging Spectrograph on Keck. The spatially resolved spectroscopy of these galaxies reveals unresolved broad-H{alpha} line regions (FWHM >1000 km s{sup -1}) likely associated with an active galactic nucleus (AGN) and regions of diffuse star formation traced by narrow-line H{alpha} emission (FWHM {approx}< 500 km s{sup -1}) dominated by multiple H{alpha}-bright stellar clumps, each contributing 1%-30% of the total clump-integrated H{alpha} emission. We find that these SMGs host high star formation rate surface densities, similar to local extreme sources, such as circumnuclear starbursts and luminous infrared galaxies. However, in contrast to these local environments, SMGs appear to be undergoing such intense activity on significantly larger spatial scales as revealed by extended H{alpha} emission over 4-16 kpc. H{alpha} kinematics show no evidence of ordered global motion as would be found in a disk, but rather large velocity offsets ({approx}few Multiplication-Sign 100 km s{sup -1}) between the distinct stellar clumps. Together with the asymmetric distribution of the stellar clumps around the AGN in these objects, it is unlikely that we are unveiling a clumpy disk structure as has been suggested in other high-redshift populations of star-forming galaxies. The SMG clumps in this sample may correspond to remnants of originally independent gas-rich systems that are in the process of merging, hence triggering the ultraluminous SMG phase.

Menendez-Delmestre, Karin; Goncalves, Thiago S. [Observatorio do Valongo, Universidade Federal do Rio de Janeiro, Ladeira do Pedro Antonio 43, Saude, Rio de Janeiro, RJ 20080-090 (Brazil); Blain, Andrew W. [California Institute of Technology, MC 105-24, Pasadena, CA 91125 (United States); Swinbank, Mark; Smail, Ian [Institute for Computational Cosmology, Durham University, Durham DH1 3LE (United Kingdom); Ivison, Rob J. [UK Astronomy Technology Centre, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Chapman, Scott C., E-mail: kmd@astro.ufrj.br [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)

2013-04-20

45

Evidence for a Clumpy, Rotating Gas Disk in a Submillimeter Galaxy at z = 4  

NASA Astrophysics Data System (ADS)

We present Karl G. Jansky Very Large Array observations of the CO(2-1) emission in the z = 4.05 submillimeter galaxy (SMG) GN20. These high-resolution data allow us to image the molecular gas at 1.3 kpc resolution just 1.6 Gyr after the big bang. The data reveal a clumpy, extended gas reservoir, 14 ± 4 kpc in diameter, in unprecedented detail. A dynamical analysis shows that the data are consistent with a rotating disk of total dynamical mass 5.4 ± 2.4 × 1011 M ?. We use this dynamical mass estimate to constrain the CO-to-H2 mass conversion factor (?CO), finding ?CO = 1.1 ± 0.6 M ?(K km s-1 pc2)-1. We identify five distinct molecular gas clumps in the disk of GN20 with masses a few percent of the total gas mass, brightness temperatures of 16-31K, and surface densities of >3200-4500 × (?CO/0.8) M ? pc-2. Virial mass estimates indicate they could be self-gravitating, and we constrain their CO-to-H2 mass conversion factor to be <0.2-0.7 M ?(K km s-1 pc2)-1. A multiwavelength comparison demonstrates that the molecular gas is concentrated in a region of the galaxy that is heavily obscured in the rest-frame UV/optical. We investigate the spatially resolved gas excitation and find that the CO(6-5)/CO(2-1) ratio is constant with radius, consistent with star formation occurring over a large portion of the disk. We discuss the implications of our results in the context of different fueling scenarios for SMGs.

Hodge, J. A.; Carilli, C. L.; Walter, F.; de Blok, W. J. G.; Riechers, D.; Daddi, E.; Lentati, L.

2012-11-01

46

Confronting the Evolving Clumpy Shell Structure of IRC +10216 with Time Dependent Dust Shell Models  

NASA Astrophysics Data System (ADS)

The prototypical dust enshrouded carbon Mira IRC +10216 is known to exhibit intrinsic structural changes on a time scale of the order of 10 yr as revealed, e.g., by CO infrared line profiles, its infrared light curves, or by high spatial resolution monitoring in the infrared. In particular, the light curves obtained over 35 yr indicate a possible periodicity on a ? 20 yr time scale, which suggests that a recurrent phenomenon might lead to the observed variations in the CO first overtone line profiles and the clumpy spatial structure. Such multi-periodicity time scales, which correspond to several (? 10) pulsation periods of the star, are predicted by consistent hydrodynamical models which include a proper treatment of dust formation. In these models discrete dust layers form on a time scale which is longer than the typical pulsation period of AGB stars (Fleischer et al. 1995). In the high spatial resolution images of IRC +10216 (Osterbart et al. 2000) several components can be identified, whose structure and brightness evolve considerably within only a few years. To shed some light on this evolution, we apply a spherically symmetric, time-dependent dust shell model which consistently describes the coupled system of hydrodynamics, chemistry, dust formation and radiative transfer (Winters et al. 2000) and confront the kinematics and brightness variations predicted by this model with the high spatial resolution observations of IRC +10216. Fleischer A.J., Gauger A., Sedlmayr E., 1995, A&A 297, 543 Osterbart R., Balega Y.Y., Blöcker T., et al., 2000, A&A 357, 169 Winters J.M., Le Bertre T., Jeong K.S., et al., 2000, A&A 361, 641

Winters, J. M.; Blöcker, T.; Hofmann, K.-H.; Weigelt, G.

47

Hot and Cold  

NSDL National Science Digital Library

In this activity, learners explore temperature changes from chemical reactions by mixing urea with water in one flask and mixing calcium chloride with water in another flask. They observe that the urea flask gets cold and the calcium chloride flask gets hot. The main idea is that some chemical processes release heat energy and are exothermic, while some chemical processes absorb heat energy and are endothermic. This activity is currently used in the Nature of Matter Unit in OMSI's Chemistry Lab. Cost estimates are per 100 learners.

Industry, Oregon M.

1997-01-01

48

Shock absorbing subassembly  

SciTech Connect

A shock absorbing subassembly, for use in an oil well drilling string above a drilling bit to absorb and reduce bit induced vibration and impact loads, wherein a shock absorber element is provided which includes at least one set of ring springs. The ring springs comprise alternating closed outer rings and closed inner rings with tapered contact surfaces on the outer and inner rings.

Zabcik, C.J.

1981-01-27

49

Composition for absorbing hydrogen  

DOEpatents

A hydrogen absorbing composition is described. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

Heung, L.K.; Wicks, G.G.; Enz, G.L.

1995-05-02

50

SHOCKED SUPERWINDS FROM THE z {approx} 2 CLUMPY STAR-FORMING GALAXY, ZC406690  

SciTech Connect

We have obtained high-resolution data of the z {approx} 2 ring-like, clumpy star-forming galaxy (SFG) ZC406690 using the VLT/SINFONI with adaptive optics (in K band) and in seeing-limited mode (in H and J bands). Our data include all of the main strong optical emission lines: [O II], [O III], H{alpha}, H{beta}, [N II], and [S II]. We find broad, blueshifted H{alpha} and [O III] emission line wings in the spectra of the galaxy's massive, star-forming clumps ({sigma} {approx} 85 km s{sup -1}) and even broader wings (up to 70% of the total H{alpha} flux, with {sigma} {approx} 290 km s{sup -1}) in regions spatially offset from the clumps by {approx}2 kpc. The broad emission likely originates from large-scale outflows with mass outflow rates from individual clumps that are 1-8 Multiplication-Sign the star formation rate (SFR) of the clumps. Based on emission line ratio diagnostics ([N II]/H{alpha} and [S II]/H{alpha}) and photoionization and shock models, we find that the emission from the clumps is due to a combination of photoionization from the star-forming regions and shocks generated in the outflowing component, with 5%-30% of the emission deriving from shocks. In terms of the ionization parameter (6 Multiplication-Sign 10{sup 7} to 10{sup 8} cm s{sup -1}, based on both the SFR and the O{sub 32} ratio), density (local electron densities of 300-1800 cm{sup -3} in and around the clumps, and ionized gas column densities of 1200-8000 M{sub Sun }pc{sup -2}), and SFR (10-40 M{sub Sun} yr{sup -1}), these clumps more closely resemble nuclear starburst regions of local ultraluminous infrared galaxies and dwarf irregulars than H II regions in local galaxies. However, the star-forming clumps are not located in the nucleus as in local starburst galaxies but instead are situated in a ring several kpc from the center of their high-redshift host galaxy, and have an overall disk-like morphology. The two brightest clumps are quite different in terms of their internal properties, energetics, and relative ages, and thus we are given a glimpse at two different stages in the formation and evolution of rapidly star-forming giant clumps at high-z.

Newman, Sarah F.; Genzel, Reinhard [Department of Astronomy, Campbell Hall, University of California, Berkeley, CA 94720 (United States); Shapiro Griffin, Kristen [Aerospace Research Laboratories, Northrop Grumman Aerospace Systems, Redondo Beach, CA 90278 (United States); Davies, Ric; Foerster-Schreiber, Natascha M.; Tacconi, Linda J.; Kurk, Jaron; Wuyts, Stijn; Genel, Shy; Buschkamp, Peter; Eisenhauer, Frank; Lutz, Dieter [Max-Planck-Institut fuer extraterrestrische Physik (MPE), Giessenbachstr.1, D-85748 Garching (Germany); Lilly, Simon J.; Carollo, C. Marcella [Institute of Astronomy, Department of Physics, Eidgenoessische Technische Hochschule, ETH Zuerich CH-8093 (Switzerland); Renzini, Alvio; Mancini, Chiara [Osservatorio Astronomico di Padova, Vicolo dellOsservatorio 5, Padova I-35122 (Italy); Bouche, Nicolas [Department of Physics and Astronomy, University of California, Santa Barbara, Santa Barbara, CA 93106 (United States); Burkert, Andreas [Department fuer Physik, Universitaets-Sternwarte Ludwig-Maximilians-Universitaet (USM), Scheinerstr. 1, Muenchen, D-81679 (Germany); Cresci, Giovanni [Istituto Nazionale di AstrofisicaOsservatorio Astronomico di Arcetri, Largo Enrico Fermi 5, I 50125 Firenze (Italy); Hicks, Erin, E-mail: sfnewman@berkeley.edu [Department of Astronomy, University of Washington, Box 351580, U.W., Seattle, WA 98195-1580 (United States); and others

2012-06-20

51

The evidence for clumpy accretion in the Herbig Ae star HR 5999  

NASA Technical Reports Server (NTRS)

Analysis of IUE high- and low-dispersion spectra of the young Herbig Ae star HR 5999 (HD 144668) covering 1978-1992 revealed dramatic changes in the Mg II h and k (2795.5, 2802.7 A) emission profiles, changes in the column density and distribution in radial velocity of accreting gas, and flux in the Ly(alpha), O I, and C IV emission lines, which are correlated with the UV excess luminosity. Variability in the spectral type inferred from the UV spectral energy distribution, ranging from A5 IV-III in high state to A7 III in the low state, was also observed. The trend of earlier inferred spectral type with decreasing wavelength and with increasing UV continuum flux has previously been noted as a signature of accretion disks in lower mass pre-main sequence stars (PMS) and in systems undergoing FU Orionis-type outbursts. Our data represent the first detection of similar phenomena in an intermediate mass (M greater than or equal to 2 solar mass) PMS star. Recent IUE spectra show gas accreting toward the star with velocities as high as plus 300 km/s, much as is seen toward beta Pic, and suggest that we also view this system through the debris disk. The absence of UV lines with the rotational broadening expected given the optical data (A7 IV, V sini=180 plus or minus 20 km/s for this system) also suggests that most of the UV light originates in the disk, even in the low continuum state. The dramatic variability in the column density of accreting gas, is consistent with clumpy accretion, such as has been observed toward beta Pic, is a hallmark of accretion onto young stars, and is not restricted to the clearing phase, since detectable amounts of accretion are present for stars with 0.5 Myr less than t(sub age) less than 2.8 Myr. The implications for models of beta Pic and similar systems are briefly discussed.

Perez, M. R.; Grady, C. A.; The, P. S.

1993-01-01

52

Submillimeter and far infrared line observations of M17 SW: A clumpy molecular cloud penetrated by UV radiation  

NASA Technical Reports Server (NTRS)

Millimeter, submillimeter, and far infrared spectroscopic observations of the M17 SW star formation region are discussed. The results require the molecular cloud near the interface to be clumpy or filamentary. As a consequence, far ultraviolet radiation from the central OB stellar cluster can penetrate into the dense molecular cloud to a depth of several pc, thus creating bright and extended (CII) emission from the photodissociated surfaces of dense atomic and molecular clumps or sheets. The extended (CII) emission throughout the molecular cloud SW of the M17 complex has a level 20 times higher than expected from a single molecular cloud interface exposed to an ultraviolet radiation field typical of the solar neighborhood. This suggests that the molecular cloud as a whole is penetrated by ultraviolet radiation and has a clumpy or filamentary structure. The number of B stars expected to be embedded in the M17 molecular cloud probably can provide the UV radiation necessary for the extended (CII) emission. Alternatively, the UV radiation could be external, if the interstellar radiation in the vicinity of M17 is higher than in the solar neighborhood.

Stutzki, J.; Stacey, G. J.; Genzel, R.; Harris, A. I.; Jaffe, d. T.; Lugten, J. B.

1987-01-01

53

Lensing Effects on Gravitational Waves in a Clumpy Universe: Effects of Inhomogeneity on the Distance-Redshift Relation  

NASA Astrophysics Data System (ADS)

The distance-redshift relation determined by means of gravitational waves in the clumpy universe is simulated numerically by taking into account the effects of gravitational lensing. It is assumed that all of the matter in the universe takes the form of randomly distributed point masses, each of which has the identical mass ML. Calculations are carried out in two extreme cases, ?>>GML/c2 and ?<clumpy universe model described above.

Yoo, Chul-Moon; Nakao, Ken-ichi; Kozaki, Hiroshi; Takahashi, Ryuichi

2007-02-01

54

Methods for absorbing neutrons  

DOEpatents

A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

Guillen, Donna P. (Idaho Falls, ID); Longhurst, Glen R. (Idaho Falls, ID); Porter, Douglas L. (Idaho Falls, ID); Parry, James R. (Idaho Falls, ID)

2012-07-24

55

Externally tuned vibration absorber  

DOEpatents

A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

Vincent, Ronald J. (Latham, NY)

1987-09-22

56

Evolution of the Fraction of Clumpy Galaxies at 0.2 < z < 1.0 in the COSMOS Field  

NASA Astrophysics Data System (ADS)

Using the Hubble Space Telescope/Advanced Camera for Surveys data in the COSMOS field, we systematically searched clumpy galaxies at 0.2 < z < 1.0 and investigated the fraction of clumpy galaxies and its evolution as a function of stellar mass, star formation rate (SFR), and specific SFR (SSFR). The fraction of clumpy galaxies in star-forming galaxies with M star > 109.5 M ? decreases with time from ~0.35 at 0.8 < z < 1.0 to ~0.05 at 0.2 < z < 0.4, irrespective of the stellar mass, although the fraction tends to be slightly lower for massive galaxies with M star > 1010.5 M ? at each redshift. On the other hand, the fraction of clumpy galaxies increases with increasing both SFR and SSFR in all the redshift ranges we investigated. In particular, we found that the SSFR dependences of the fractions are similar among galaxies with different stellar masses, and the fraction at a given SSFR does not depend on the stellar mass in each redshift bin. The evolution of the fraction of clumpy galaxies from z ~ 0.9 to z ~ 0.3 seems to be explained by such SSFR dependence of the fraction and the evolution of SSFRs of star-forming galaxies. The fraction at a given SSFR also appears to decrease with time, but this can be due to the effect of the morphological k correction. We suggest that these results are understood by the gravitational fragmentation model for the formation of giant clumps in disk galaxies, where the gas mass fraction is a crucial parameter. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. Also based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. Also based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; the XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA; the European Southern Observatory under Large Program 175.A-0839, Chile; Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory and the National Optical Astronomy Observatory, which are operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement with the National Science Foundation; and the Canada-France-Hawaii Telescope with MegaPrime/MegaCam operated as a joint project by the CFHT Corporation, CEA/DAPNIA, the NRC and CADC of Canada, the CNRS of France, TERAPIX, and the University of Hawaii.

Murata, K. L.; Kajisawa, M.; Taniguchi, Y.; Kobayashi, M. A. R.; Shioya, Y.; Capak, P.; Ilbert, O.; Koekemoer, A. M.; Salvato, M.; Scoville, N. Z.

2014-05-01

57

Cold Water Vapor in the Barnard 5 Molecular Cloud  

NASA Astrophysics Data System (ADS)

After more than 30 yr of investigations, the nature of gas-grain interactions at low temperatures remains an unresolved issue in astrochemistry. Water ice is the dominant ice found in cold molecular clouds; however, there is only one region where cold (~10 K) water vapor has been detected—L1544. This study aims to shed light on ice desorption mechanisms under cold cloud conditions by expanding the sample. The clumpy distribution of methanol in dark clouds testifies to transient desorption processes at work—likely to also disrupt water ice mantles. Therefore, the Herschel HIFI instrument was used to search for cold water in a small sample of prominent methanol emission peaks. We report detections of the ground-state transition of o-H2O (J = 110-101) at 556.9360 GHz toward two positions in the cold molecular cloud, Barnard 5. The relative abundances of methanol and water gas support a desorption mechanism which disrupts the outer ice mantle layers, rather than causing complete mantle removal.

Wirström, E. S.; Charnley, S. B.; Persson, C. M.; Buckle, J. V.; Cordiner, M. A.; Takakuwa, S.

2014-06-01

58

Advanced neutron absorber materials  

DOEpatents

A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

Branagan, Daniel J. (Idaho Falls, ID); Smolik, Galen R. (Idaho Falls, ID)

2000-01-01

59

Multispectral metamaterial absorber.  

PubMed

We present the simulation, implementation, and measurement of a multispectral metamaterial absorber (MSMMA) and show that we can realize a simple absorber structure that operates in the mid-IR and terahertz (THz) bands. By embedding an IR metamaterial absorber layer into a standard THz metamaterial absorber stack, a narrowband resonance is induced at a wavelength of 4.3 ?m. This resonance is in addition to the THz metamaterial absorption resonance at 109 ?m (2.75 THz). We demonstrate the inherent scalability and versatility of our MSMMA by describing a second device whereby the MM-induced IR absorption peak frequency is tuned by varying the IR absorber geometry. Such a MSMMA could be coupled with a suitable sensor and formed into a focal plane array, enabling multispectral imaging. PMID:24690713

Grant, J; McCrindle, I J H; Li, C; Cumming, D R S

2014-03-01

60

Project COLD.  

ERIC Educational Resources Information Center

Describes Project COLD (Climate, Ocean, Land, Discovery) a scientific study of the Polar Regions, a collection of 35 modules used within the framework of existing subjects: oceanography, biology, geology, meterology, geography, social science. Includes a partial list of topics and one activity (geodesic dome) from a module. (Author/SK)

Kazanjian, Wendy C.

1982-01-01

61

Internal absorber solar collector  

DOEpatents

Thin solar collecting panels are described made from arrays of small rod collectors consisting of a refracting dielectric rod lens with an absorber imbedded within it and a reflecting mirror coated on the back side of the dielectric rod. Non-tracking collector panels on vertical walls or roof tops receive approximately 90% of solar radiation within an acceptance zone 60.degree. in elevation angle by 120.degree. or more in the azimuth sectors with a collector concentration ratio of approximately 3.0. Miniaturized construction of the circular dielectric rods with internal absorbers reduces the weight per area of glass, plastic and metal used in the collector panels. No external parts or insulation are needed as heat losses are low due to partial vacuum or low conductivity gas surrounding heated portions of the collector. The miniature internal absorbers are generally made of solid copper with black selective surface and the collected solar heat is extracted at the collector ends by thermal conductivity along the absorber rods. Heat is removed from end fittings by use of liquid circulants. Several alternate constructions are provided for simplifying collector panel fabrication and for preventing the thermal expansion and contraction of the heated absorber or circulant tubes from damaging vacuum seals. In a modified version of the internal absorber collector, oil with temperature dependent viscosity is pumped through a segmented absorber which is now composed of closely spaced insulated metal tubes. In this way the circulant is automatically diverted through heated portions of the absorber giving higher collector concentration ratios than theoretically possible for an unsegmented absorber.

Sletten, Carlyle J. (106 Nagog Hill Rd., Acton, MA 01720); Herskovitz, Sheldon B. (88 Hammond St., Acton, MA 01720); Holt, F. S. (46 Emerson Rd., Winchester, MA 01890); Sletten, E. J. (Chestnut Hill Rd. R.F.D. Rte. #4, Amherst, NH 03031)

1981-01-01

62

Lipid-absorbing polymers  

NASA Technical Reports Server (NTRS)

The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

Marsh, H. E., Jr.; Wallace, C. J.

1973-01-01

63

Smooth and clumpy dust distributions in AGN: a direct comparison of two commonly explored infrared emission models  

NASA Astrophysics Data System (ADS)

The geometry of dust distribution within the inner regions of active galactic nuclei (AGN) is still a debated issue and relates directly to the AGN unified scheme. Traditionally, models discussed in the literature assume one of the two distinct dust distributions in what is believed to be a toroidal region around the supermassive black holes: a continuous distribution, customarily referred to as smooth, and a concentration of dust in clumps or clouds, referred to as clumpy. In this paper we perform a thorough comparison between two of the most popular models in the literature, namely the smooth models by Fritz et al. and the clumpy models by Nenkova et al., in their common parameter space. Particular attention is paid to the silicate features at ˜9.7 and ˜18 ?m, the width of the infrared bump, the near-infrared index and the luminosity at 12.3 ?m, all previously reported as possible diagnostic tools to distinguish between the two dust distributions. We find that, due to different dust chemical compositions used in the two models, the behaviour of the silicate features at 9.7 and 18 ?m is quite distinct between the two models. The width of the infrared bump and the peak of the infrared emission can take comparable values; their distributions do, however, vary. The near-infrared index is also quite different, due partly to the primary sources adopted by the two models. Models with matched parameters do not produce similar spectral energy distributions (SEDs) and virtually no random parameter combinations can result in seemingly identical SEDs.

Feltre, A.; Hatziminaoglou, E.; Fritz, J.; Franceschini, A.

2012-10-01

64

Hot, Cold, and Really Cold.  

ERIC Educational Resources Information Center

Describes a physics experiment investigating temperature prediction and the relationship between the physical properties of heat units, melting, dissolving, states of matter, and energy loss. Details the experimental setup, which requires hot and cold water, a thermometer, and ice. Notes that the experiment employs a deliberate counter-intuitive…

Leyden, Michael

1997-01-01

65

Low Frequency Vibration Absorber.  

National Technical Information Service (NTIS)

This patent application discloses a mounting assembly for absorbing low frequency vibrational energy as produced by a source and isolating a base member therefrom. The mounting assembly includes a central metallic ring, non-metallic foam rings located on ...

N. J. Dubois B. G. Gauthier

1990-01-01

66

Radar Absorbing Material Design.  

National Technical Information Service (NTIS)

Low observable platforms have extremely low radar cross section specifications that cannot be achieved by shaping alone. The application of radar absorbing material is necessary, in which case the appropriate constitutive parameters and thickness must be ...

C. K. Yuzcelik

2003-01-01

67

Coping with Cold Sores  

MedlinePLUS

... What's that? Adam wondered. What Is a Cold Sore? Cold sores are small blisters that is reddish ... always found inside the mouth.) What Causes Cold Sores? Cold sores are caused by a virus called ...

68

Review of Radar Absorbing Materials.  

National Technical Information Service (NTIS)

Radar is a sensitive detection tool and since its development, methods for reducing microwave reflections have been explored. Radar absorbers can be classified as impedance matching or resonant absorbers. Radar absorbing materials are made from resistive ...

P. Saville

2005-01-01

69

Cold soybean management decision system based on JSP  

Microsoft Academic Search

In accordance with the requirements management of cold soybean growth characters integrated climatic conditions, soil fertility status of region, the laws of cold soybean absorbing nutrients, the soil nutrient supplying capacity and other various factors to set up models and rules. The system based on the object-oriented technology of JSP VB VC had some trials on middle plant part (Hailun),

Song Yihong; Yang Yushu; Li Xiao

2010-01-01

70

Shock absorber servicing tool  

NASA Technical Reports Server (NTRS)

A tool to assist in the servicing of a shock absorber wherein the shock absorber is constructed of a pair of aligned gas and liquid filled chambers. Each of the chambers is separated by a movable separator member. Maximum efficiency of the shock absorber is achieved in the locating of a precise volume of gas within the gas chamber and a precise volume of liquid within the liquid chamber. The servicing tool of this invention employs a rod which is to connect with the separator and by observation of the position of the rod with respect to the gauge body, the location of the separator is ascertained even though it is not directly observable.

Koepler, Jack L. (Inventor); Hill, Robert L. (Inventor)

1981-01-01

71

Common cold  

PubMed Central

Introduction Each year, children suffer up to 5 colds and adults have 2-3 infections, leading to time off school or work, and considerable discomfort. Most symptoms resolve within a week, but coughs often persist for longer. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments for common cold? We searched: Medline, Embase, The Cochrane Library and other important databases up to May 2007 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 19 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: analgesics or anti-inflammatory drugs, antibiotics, antihistamines, decongestants (norephedrine, oxymetazoline, or pseudoephedrine), decongestants plus antihistamine, echinacea, steam inhalation, vitamin C, and zinc (intranasal gel or lozenges).

2008-01-01

72

Common cold  

PubMed Central

Introduction Each year, children suffer up to 5 colds and adults have two to three infections, leading to time off school or work, and considerable discomfort. Most symptoms resolve within 1 week, but coughs often persist for longer. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments for common cold? We searched: Medline, Embase, The Cochrane Library, and other important databases up to January 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 21 systematic reviews and RCTs that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: analgesics or anti-inflammatory drugs, antibiotics, antihistamines, decongestants for short-term and for long-term relief, decongestants plus antihistamines, echinacea, steam inhalation, vitamin C, and zinc (intranasal gel or lozenges).

2011-01-01

73

Annular burnable absorber rod  

SciTech Connect

This patent describes a neutron irradiation environment of a water cooled and moderated reactor core a fuel assembly having a discrete annular burnable absorber rod, the rod being free of nuclear fuel material the rod comprising a first elongated hollow tube having opposed ends, a second elongated hollow tube having opposed ends. The first and second tubes are constructed of a zirconium material, the first and second tubes concentrically arranged about a common axis to provide a coextensive annular space therebetween and a path for the water through the first tube along the common axis. A sealing means seals the annular space at common opposed ends of the first and second tube and a hollow niobium tubular support is arranged within the annular space. The tubular support has an inner and outer surface, a layer of burnable neutron absorber material provided on at least a portion of one of the surfaces of the support the layer of the burnable neutron absorber material selected from the group of boron compounds consisting of boron carbide, boron nitride and zirconium diboride; and the layer of the burnable neutron absorber material having a thickness between 0.002 to 0.010 inches.

Chubb, W.

1986-12-02

74

Absorbed dose water calorimeter  

Microsoft Academic Search

An absorbed dose water calorimeter that takes advantage of the low thermal diffusivity of water and the water-imperviousness of polyethylene film. An ultra-small bead thermistor is sandwiched between two thin polyethylene films stretched between insulative supports in a water bath. The polyethylene films insulate the thermistor and its leads, the leads being run out from between the films in insulated

Domen

1982-01-01

75

Neutron Absorbing Alloys  

DOEpatents

The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

Mizia, Ronald E. (Idaho Falls, ID); Shaber, Eric L. (Idaho Falls, ID); DuPont, John N. (Whitehall, PA); Robino, Charles V. (Albuquerque, NM); Williams, David B. (Bethlehem, PA)

2004-05-04

76

Burnable neutron absorbers  

Microsoft Academic Search

Method of making a burnable neutron absorber of boron carbide in a matrix of aluminum oxide. In the practice of this method, boron-carbide particles are coated with a pore former and then they are mixed in a slurry with aluminum oxide powder. When the slurry is subsequently dried and sintered, the pore former is burned out and a body is

B. M. Argall; P. J. Kuchirka; K. C. Radford

1985-01-01

77

Solar Radiation Absorbing Material.  

National Technical Information Service (NTIS)

Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a micr...

J. M. Googin C. R. Schmitt J. M. Schreyer H. D. Whitehead

1976-01-01

78

A Shock Absorber.  

National Technical Information Service (NTIS)

The invention involves a shock absorber consisting of a cylindrical housing (containing a coaxially placed guide cylinder forming a working space equipped with by-pass apertures), a chamber (formed by the housing and the floating piston), and a working pi...

N. N. Rakhmanov

1969-01-01

79

Lifetimes of Saturable Absorbers  

Microsoft Academic Search

THE use of saturable absorbers such as aluminium phthalocyanine for the passive Q-switching of ruby lasers1 raises the question of the lifetime of the active molecule. We have measured the lifetime of that state of aluminium phthalocyanine which corresponds to absorption at or near 6943 Å. Similar data for magnesium phthalocyanine have been obtained, for comparison with literature values.

P. W. A. Bowe; W. E. K. Gibbs; J. Tregellas-Williams

1966-01-01

80

The Nature of H?-selected Galaxies at z > 2. II. Clumpy Galaxies and Compact Star-forming Galaxies  

NASA Astrophysics Data System (ADS)

We present the morphological properties of H?-selected galaxies at z > 2 in SXDF-UDS-CANDELS field. With high-resolution optical/near-infrared images obtained by the Hubble Space Telescope, we identify giant clumps within the H? emitters (HAEs). We find that at least 41% of our sample shows clumpy structures in the underlying disks. The color gradient of clumps is commonly seen in the sense that the clumps near the galactic center tend to be redder than those in the outer regions. The mid-infrared detection in galaxies with red clumps and the spatial distribution of H? emission suggest that dusty star-formation activity is probably occurring in the nuclear red clumps. A gas supply to a bulge component through clump migration is one of the most potent physical processes for producing such dusty star-forming clumps and forming massive bulges in local early-type galaxies. They would become large quiescent galaxies at later times just by consumption or blowout of remaining gas. Also, while most of the HAEs have extended disks, we observe two massive, compact HAEs whose stellar surface densities are significantly higher. They are likely to be the direct progenitors of massive, compact quiescent galaxies at z = 1.5-2.0. Two evolutionary paths to massive quiescent galaxies are devised to account for both the size growth of quiescent galaxies and their increased number density from z ~ 2 to z = 0.

Tadaki, Ken-ichi; Kodama, Tadayuki; Tanaka, Ichi; Hayashi, Masao; Koyama, Yusei; Shimakawa, Rhythm

2014-01-01

81

Apollo couch energy absorbers  

NASA Technical Reports Server (NTRS)

Load attenuators for the Apollo spacecraft crew couch and its potential applications are described. Energy absorption is achieved through friction and cyclic deformation of material. In one concept, energy absorption is accomplished by rolling a compressed ring of metal between two surfaces. In another concept, energy is absorbed by forcing a plastically deformed washer along a rod. Among the design problems that had to be solved were material selection, fatigue life, ring slippage, lubrication, and friction loading.

Wesselski, C. J.; Drexel, R. E.

1972-01-01

82

Cold confusion  

SciTech Connect

On March 23 two chemists, Martin Fleischmann and Stanley Pons startled the world with a press conference at the University of Utah where they announced that they had achieved nuclear fusion at room temperatures. As evidence they cited the production of ''excess'' amounts of heat in an electrochemical apparatus and observation of neutron production. While the production of heat in a chemical apparatus is not in itself unusual the observation of neutrons is certainly extraordinary. As it turned out, though, careful measurements of the neutron production in electrochemical apparatus similar to that used by Fleischmann and Pons carried out at dozens of other laboratories has shown that the neutron production fails by many orders of magnitude to support the assertion by Fleischmann and Pons that their discovery represents a new and cheap source of fusion power. In particular, independent measurements of the neutron production rate suggest that the actual rate of fusion energy production probably does not exceed 1 trillionth of a watt. This paper discusses the feasibility that cold fusion is actually being achieved. 7 refs.

Chapline, G.

1989-07-01

83

Shock absorber in Ignalina NPP.  

National Technical Information Service (NTIS)

Theoretical calculation and experimental analysis of models of shock absorber in Ignalina NPP is presented. The results obtained from the investigation with model of shock absorber coincide with the theoretical calculation. (author). 2 figs., 3 refs. (Ato...

A. Bulavas J. Muralis

1996-01-01

84

Corrosion resistant neutron absorbing coatings  

DOEpatents

A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

Choi, Jor-Shan (El Cerrito, CA); Farmer, Joseph C. (Tracy, CA); Lee, Chuck K. (Hayward, CA); Walker, Jeffrey (Gaithersburg, MD); Russell, Paige (Las Vegas, NV); Kirkwood, Jon (Saint Leonard, MD); Yang, Nancy (Lafayette, CA); Champagne, Victor (Oxford, PA)

2012-05-29

85

Corrosion resistant neutron absorbing coatings  

DOEpatents

A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

2013-11-12

86

Machine for Testing Shock Absorbers.  

National Technical Information Service (NTIS)

The machine is for testing shock absorbers used in tanks, personnel carriers, and like vehicles. A shock absorber is tested by mounting it on one end of a piston which is reciprocated by hydraulic fluid under pressure. The other end of the shock absorber ...

E. W. Posse C. E. Rutledge

1964-01-01

87

Absorber for solar power.  

PubMed

A simple, economical absorber utilizing a new principle of operation to achieve very low reradiation losses while generating temperatures limited by material properties of quartz is described. Its performance is analyzed and indicates approximately 90% thermal efficiency and 73% conversion efficiency for an earth based unit with moderately concentrated (~tenfold) sunlight incident. It is consequently compatible with the most economic of concentrator mirrors (stamped) or mirrors deployable in space. Space applications are particularly attractive, as temperatures significantly below 300 K are possible and permit even higher conversion efficiency. PMID:20134700

Powell, W R

1974-10-01

88

Cold Signaling and Cold Response in Plants  

PubMed Central

Plants are constantly exposed to a variety of environmental stresses. Freezing or extremely low temperature constitutes a key factor influencing plant growth, development and crop productivity. Plants have evolved a mechanism to enhance tolerance to freezing during exposure to periods of low, but non-freezing temperatures. This phenomenon is called cold acclimation. During cold acclimation, plants develop several mechanisms to minimize potential damages caused by low temperature. Cold response is highly complex process that involves an array of physiological and biochemical modifications. Furthermore, alterations of the expression patterns of many genes, proteins and metabolites in response to cold stress have been reported. Recent studies demonstrate that post-transcriptional and post-translational regulations play a role in the regulation of cold signaling. In this review article, recent advances in cold stress signaling and tolerance are highlighted.

Miura, Kenji; Furumoto, Tsuyoshi

2013-01-01

89

Metamaterial electromagnetic wave absorbers.  

PubMed

The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch-the metamaterial perfect absorber (MPA)-has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed. PMID:22627995

Watts, Claire M; Liu, Xianliang; Padilla, Willie J

2012-06-19

90

Solar energy absorbing panel  

SciTech Connect

A solar energy absorbing panel is provided which may be integrally incorporated into a conventional building structure so that it does not protrude from the normal contour of the building , and which utilizes components of the building structure as a part of the collecting apparatus to thereby minimize the cost thereof. The panel is composed of a plurality of interconnected side-by-side, generally u-shaped sections, with the adjacent sides of adjacent sections forming parallel fins which facilitate transfer of heat to air passed therealong. Also, slot means are provided at one end edge of the panel which is adapted to receive the other end edge of another like panel therein, whereby the panels may be joined in an end-to-end arrangement.

McArthur, W.H.

1981-09-01

91

Reflection measurements of microwave absorbers  

NASA Astrophysics Data System (ADS)

A swept-frequency interferometer is described for making rapid, real-time assessments of localized inhomogeneities in planar microwave absorber panels. An aperture-matched exponential horn is used to reduce residual reflections in the system to about -37 dB. This residual reflection is adequate for making comparative measurements on planar absorber panels whose reflectivities usually fall in the -15 to -25 dB range. Reflectivity measurements on a variety of planar absorber panels show that multilayer Jaumann absorbers have the greatest inhomogeneity, while honeycomb absorbers generally have excellent homogeneity within a sheet and from sheet to sheet. The test setup is also used to measure the center frequencies of resonant absorbers. With directional couplers and aperture-matched exponential horns, the technique can be easily applied in the standard 2 to 40 GHz waveguide bands.

Baker, Dirk E.; van der Neut, Cornelis A.

1988-12-01

92

Electrochemically regenerable carbon dioxide absorber  

NASA Technical Reports Server (NTRS)

Preliminary designs were generated for two electrochemically regenerable carbon dioxide absorber concepts. Initially, an electrochemically regenerable absorption bed concept was designed. This concept incorporated the required electrochemical regeneration components in the absorber design, permitting the absorbent to be regenerated within the absorption bed. This hardware was identified as the electrochemical absorber hardware. The second hardware concept separated the functional components of the regeneration and absorption process. This design approach minimized the extravehicular activity component volume by eliminating regeneration hardware components within the absorber. The electrochemical absorber hardware was extensively characterized for major operating parameters such as inlet carbon dioxide partial pressure, process air flow rate, operational pressure, inlet relative humidity, regeneration current density and absorption/regeneration cycle endurance testing.

Woods, R. R.; Marshall, R. D.; Schubert, F. H.; Heppner, D. B.

1979-01-01

93

Plants absorb heavy metals  

SciTech Connect

Decontamination of heavy metals-polluted soils remains one of the most intractable problems of cleanup technology. Currently available techniques include extraction of the metals by physical and chemical means, such as acid leaching and electroosmosis, or immobilization by vitrification. There are presently no techniques for cleanup which are low cost and retain soil fertility after metals removal. But a solution to the problem could be on the horizon. A small but growing number of plants native to metalliferous soils are known to be capable of accumulating extremely high concentrations of metals in their aboveground portions. These hyperaccumulators, as they are called, contain up to 1,000 times larger metal concentrations in their aboveground parts than normal species. Their distribution is global, including many different families of flowering plants of varying growth forms, from herbaceous plants to trees. Hyperaccumulators absorb metals they do not need for their own nutrition. The metals are accumulated in the leaf and stem vacuoles, and to a lesser extent in the roots.

Parry, J.

1995-02-01

94

Review of 'cold fusion'.  

National Technical Information Service (NTIS)

This review describes the results from the following works: (1) to overview the chronological history of 'cold fusion' including the International Conferences on cold fusion (ICCF-3 and ICCF-4), (2) to overview the various theories which can explain the '...

1995-01-01

95

Exercising in Cold Weather  

MedlinePLUS

... to cold can cause health problems such as hypothermia, a dangerous drop in body temperature. If you ... hat, scarf, and gloves. Know the signs of hypothermia: l Watch for signs of hypothermia: cold feet ...

96

Cough and Cold Medicine Abuse  

MedlinePLUS

... and Cold Medicine Abuse DrugFacts: Cough and Cold Medicine Abuse Email Facebook Twitter Revised May 2014 Some ... diverted for abuse. How Are Cough and Cold Medicines Abused? Cough and cold medicines are usually consumed ...

97

Hypothermia: A Cold Weather Hazard  

MedlinePLUS

... cold air. But, not everyone knows that cold weather can also lower the temperature inside your body. ... cold it is where you are. Check the weather forecasts for windy and cold weather. Try to ...

98

Absorbent product to absorb fluids. [for collection of human wastes  

NASA Technical Reports Server (NTRS)

A multi-layer absorbent product for use in contact with the skin to absorb fluids is discussed. The product utilizes a water pervious facing layer for contacting the skin, overlayed by a first fibrous wicking layer, the wicking layer preferably being of the one-way variety in which fluid or liquid is moved away from the facing layer. The product further includes a first container section defined by inner and outer layer of a water pervious wicking material between which is disposed a first absorbent mass. A second container section defined by inner and outer layers between which is disposed a second absorbent mass and a liquid impermeable/gas permeable layer. Spacesuit applications are discussed.

Dawn, F. S.; Correale, J. V. (inventors)

1982-01-01

99

Acoustic performance of membrane absorbers  

NASA Astrophysics Data System (ADS)

This paper is a report on the acoustic properties of absorbing elements, which consist of metal membranes and show good sound absorption at low and medium frequencies over more than one octave. The studies refer to the sound absorption coefficient and acoustic impedance at normal incidence of the sound waves. It is shown that the behavior of the absorbing element is mainly determined by a combination of Helmholtz resonance and plate resonance. The parameters of the separate resonators are determined both by theory and experiment and serve as input data for a simplified calculation model, which can be used as an auxiliary tool for designing membrane absorber silencers.

Frommhold, W.; Fuchs, H. V.; Sheng, S.

1994-03-01

100

Self-Regulating Shock Absorber  

NASA Technical Reports Server (NTRS)

Mechanical shock absorber keeps frictional damping force within tolerable limit. Its damping force does not increase with coefficient of friction between energy-absorbing components; rather, frictional damping force varies only slightly. Relatively insensitive to manufacturing variations and environmental conditions altering friction. Does not exhibit high breakaway friction and consequent sharp increase followed by sharp decrease in damping force at beginning of stroking. Damping force in absorber does not vary appreciably with speed of stroking. In addition, not vulnerable to leakage of hydraulic fluid.

Wesselski, Clarence J.

1995-01-01

101

Review in Sound Absorbing Materials  

Microsoft Academic Search

This article is a bibliographical revision concerning acoustic absorbing materials, also known as poroelastics. These absorbing\\u000a materials are a passive medium use extensively in the industry to reduce noise. This review presents the fundamental parameters\\u000a that define each of the parts comprising these materials, as well as current experimental methods used to measure said parameters.\\u000a Further along, we will analyze

X. Sagartzazu; L. Hervella-Nieto; J. M. Pagalday

2007-01-01

102

Packed Alumina Absorbs Hypergolic Vapors  

NASA Technical Reports Server (NTRS)

Beds of activated alumina effective as filters to remove hypergolic vapors from gas streams. Beds absorb such substances as nitrogen oxides and hydrazines and may also absorb acetylene, ethylene, hydrogen sulfide, benzene, butadiene, butene, styrene, toluene, and xoylene. Bed has no moving parts such as pumps, blowers and mixers. Reliable and energy-conservative. Bed readily adapted to any size from small portable units for use where little vapor release is expected to large stationary units for extensive transfer operations.

Thomas, J. J.; Mauro, D. M.

1984-01-01

103

Absorber pin development in Europe  

Microsoft Academic Search

The neutron absorbing material chosen for the absorber elements of the European fast reactor (EFR) is boron carbide. Various pin designs are studied in Europe: (1) vented helium-bonded pins chosen for prototype fast reactor (PFR) control rods, (2) vented sodium-bonded pins chosen for the Phenix and Superphenix control rods, (3) vented shrouded sodium-bonded pins chosen for future loads of Superphenix

A. Languille; J. Escleine; B. Kryger; B. Munroe; B. Steinmetz

1992-01-01

104

Countercurrent flow absorber and desorber  

DOEpatents

Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system.

Wilkinson, William H. (Columbus, OH)

1984-01-01

105

Tuned gyroscope with dynamic absorber  

NASA Astrophysics Data System (ADS)

Dry tuned gyroscopes are subjected to random drift, noise, characteristically large transmissibility at structural resonance, bias shifts vs temperature, etc. The dynamic model of a tuned gyro is represented by a coupled multiple degree of freedom system, where bearing induced vibrational outputs pass through structural resonances. The article describes the application of the rotating dynamic vibration absorber, as a method of controlling the level of gyro structural radial and axial vibrations. By providing damping to the dynamic absorber, a system becomes less sensitive to tuning the resonant frequencies of the absorber system to the corresponding radial and axial gyro resonance frequencies. It significantly reduces rotor transmissibilities, keeps bias from shifting when bearing noise passes through resonances vs temperature, improves g and g-squared sensitivity, as well as the gyro's ability to withstand random vibration. Equations of motion of the gyro with the dynamic absorber, and the absorber separately from the gyro are derived. Theoretical and experimental data of the whole system and the absorber itself are discussed.

Strugach, M.

106

Dusty Structure Around Type-I Active Galactic Nuclei: Clumpy Torus Narrow-line Region and Near-nucleus Hot Dust  

NASA Astrophysics Data System (ADS)

We fitted Spitzer/IRS ~ 2-35 ?m spectra of 26 luminous quasi-stellar objects in an attempt to define the main emission components. Our model has three major components: a clumpy torus, dusty narrow-line region (NLR) clouds, and a blackbody-like dust. The models utilize the clumpy torus of Nenkova et al. and are the first to allow its consistent check in type-I active galactic nuclei (AGNs). Single torus models and combined torus-NLR models fail to fit the spectra of most sources, but three-component models adequately fit the spectra of all sources. We present torus inclination, cloud distribution, covering factor, and torus mass for all sources and compare them with bolometric luminosity, black hole mass, and accretion rate. The torus mass is found to be correlated with the bolometric luminosity of the sources. Torus-covering factor may also be (anti-)correlated, if some possibly anomalous points are omitted. We find that a substantial amount of the ~2-7 ?m radiation originates from a hot dust component, which is likely situated in the innermost part of the torus. The luminosity radiated by this component and its covering factor are comparable to those of the torus. We quantify the emission by the NLR clouds and estimate their distance from the center. The distances are ~700 times larger than the dust sublimation radius, and the NLR-covering factor is about 0.07. The total covering factor by all components is in good agreement with the known AGN type-I:type-II ratio.

Mor, Rivay; Netzer, Hagai; Elitzur, Moshe

2009-11-01

107

Cold fusion: Alchemist's dream  

NASA Astrophysics Data System (ADS)

In this report the following topics relating to cold fusion are discussed: muon catalyzed cold fusion; piezonuclear fusion; sundry explanations pertaining to cold fusion; cosmic ray muon catalyzed cold fusion; vibrational mechanisms in excited states of D2 molecules; barrier penetration probabilities within the hydrogenated metal lattice/piezonuclear fusion; branching ratios of D2 fusion at low energies; fusion of deuterons into He-4; secondary D+T fusion within the hydrogenated metal lattice; helium-3 to helium-4 ratio within the metal lattice; shock induced fusion; and anomalously high isotopic ratios of helium-3/helium-4.

Clayton, E. D.

1989-09-01

108

Nonventing, Regenerable, Lightweight Heat Absorber  

NASA Technical Reports Server (NTRS)

A lightweight, regenerable heat absorber (RHA), developed for rejecting metabolic heat from a space suit, may also be useful on Earth for short-term cooling of heavy protective garments. Unlike prior space-suit-cooling systems, a system that includes this RHA does not vent water. The closed system contains water reservoirs, tubes through which water is circulated to absorb heat, an evaporator, and an absorber/radiator. The radiator includes a solution of LiCl contained in a porous material in titanium tubes. The evaporator cools water that circulates through a liquid-cooled garment. Water vapor produced in the evaporator enters the radiator tubes where it is absorbed into the LiCl solution, releasing heat. Much of the heat of absorption is rejected to the environment via the radiator. After use, the RHA is regenerated by heating it to a temperature of 100 C for about 2 hours to drive the absorbed water back to the evaporator. A system including a prototype of the RHA was found to be capable of maintaining a temperature of 20 C while removing heat at a rate of 200 W for 6 hours.

Izenson, Michael G.; Chen, Weibo

2008-01-01

109

Low temperature selective absorber research  

NASA Astrophysics Data System (ADS)

Research carried out since 1979 on selective absorbers is surveyed, with particular attention given to the low-temperature coatings seen as promising for flat plate and evacuated tube applications. The most thoroughly investigated absorber is black chrome, which is highly selective and is the most durable low-temperature absorber. It is believed that other materials, because of their low cost and lower content of strategic materials, may eventually supplant black chrome. Among these candidates are chemically converted black nickel; anodically oxidized nickel, zinc, and copper composites; and nickel or other low-cost multilayer coatings. In reviewing medium and high-temperature research, black chrome, multilayer coatings and black cobalt are seen as best medium-temperature candidates. For high temperatures, an Al2O3/Pt-Al203 multilayer composite or the zirconium diboride coating is preferred.

Herzenberg, S. A.; Silberglitt, R.

110

Damage tolerant light absorbing material  

DOEpatents

A light absorbing article comprised of a composite of carbon-bonded carbon fibers, is prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000 C to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm[sup 3]. 9 figures.

Lauf, R.J.; Hamby, C. Jr.; Akerman, M.A.; Seals, R.D.

1993-09-07

111

Damage tolerant light absorbing material  

DOEpatents

A light absorbing article comprised of a composite of carbon-bonded carbon fibers, prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000.degree. C. to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm.sup.3.

Lauf, Robert J. (Oak Ridge, TN); Hamby, Jr., Clyde (Harriman, TN); Akerman, M. Alfred (Knoxville, TN); Seals, Roland D. (Oak Ridge, TN)

1993-01-01

112

Counterflow absorber for an absorption refrigeration system  

DOEpatents

An air-cooled, vertical tube absorber for an absorption refrigeration system is disclosed. Strong absorbent solution is supplied to the top of the absorber and refrigerant vapor is supplied to the bottom of the absorber to create a direct counterflow of refrigerant vapor and absorbent solution in the absorber. The refrigeration system is designed so that the volume flow rate of refrigerant vapor in the tubes of the absorber is sufficient to create a substantially direct counterflow along the entire length of each tube in the absorber. This provides several advantages for the absorber such as higher efficiency and improved heat transfer characteristics, and allows improved purging of non-condensibles from the absorber.

Reimann, Robert C. (Lafayette, NY) [Lafayette, NY

1984-01-01

113

Oil and fat absorbing polymers  

NASA Technical Reports Server (NTRS)

A method is described for forming a solid network polymer having a minimal amount of crosslinking for use in absorbing fats and oils. The polymer remains solid at a swelling ratio in oil or fat of at least ten and provides an oil absorption greater than 900 weight percent.

Marsh, H. E., Jr. (inventor)

1977-01-01

114

Specific Extra-Corporeal Absorbents.  

National Technical Information Service (NTIS)

A number of new absorbent polymers for use in extra-corporeal loops (and also for possible use via ingestion) were prepared and studied. Attention was concentrated upon means for the removal of urea. Negative results were obtained in attempts to employ al...

H. P. Gregor J. S. Stamberg K. R. Brennen F. C. Chlanda C. Gryte

1970-01-01

115

Tuned gyroscope with dynamic absorber  

Microsoft Academic Search

Dry tuned gyroscopes are subjected to random drift, noise, characteristically large transmissibility at structural resonance, bias shifts vs temperature, etc. The dynamic model of a tuned gyro is represented by a coupled multiple degree of freedom system, where bearing induced vibrational outputs pass through structural resonances. The article describes the application of the rotating dynamic vibration absorber, as a method

M. Strugach

1985-01-01

116

Acceleration Sensitive Shock Absorber Valve.  

National Technical Information Service (NTIS)

The patent describes a pressurized air-oil, telescopically configured, shock absorber of the type that may be incorporated in an aircraft landing gear or other devices subject to high structural stresses caused by high impact loadings. It consists of a su...

J. C. Brady K. J. Fewel

1972-01-01

117

OVI Absorbers Over Cosmic Time  

NASA Astrophysics Data System (ADS)

OVI absorption is observed in a wide variety of astrophysical environments (e.g. IGM, CGM, local ISM, HVC, DLA etc.). The high cosmic abundance of oxygen, high ionization potential (IP = 113.9 eV) and high oscillator strength of OVI 1031,1037 doublets make the OVI transition a useful and well-studied tracer of diffuse and/or high temperature regions of the Universe. We have built a sample of intervening OVI absorbers in the Lyman-alpha forest of 18 high redshift (z>2) UV bright QSOs, observed with the VLT/UVES. This is the largest sample of high-z OVI absorber observed with a high resolution spectrograph. In this talk, the author will present various results related to the high redshift IGM as probed by OVI absorbers and compare them to low redshift IGM studies. The gas that lies in the immediate vicinity of galaxies (i.e. so called CGM gas), on the other hand, is of great interest to study the gas flows in galaxies. Tracing inflow/outflow is essential for understanding formation and evolution of galaxies. In the last part of the talk, the author will highlight some of his recent studies on intermediate redshift (0.4 < z < 1.0) OVI absorption in MgII selected absorbers, which presumably trace the CGM environment.

Muzahid, Sowgat

2014-01-01

118

Radiative Transfer in a Clumpy Universe. IV. New Synthesis Models of the Cosmic UV/X-Ray Background  

NASA Astrophysics Data System (ADS)

We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative transfer code CUBA: (1) the sawtooth modulation of the background intensity from resonant line absorption in the Lyman series of cosmic hydrogen and helium; (2) the X-ray emission from the obscured and unobscured quasars that gives origin to the X-ray background; (3) a piecewise parameterization of the distribution in redshift and column density of intergalactic absorbers that fits recent measurements of the mean free path of 1 ryd photons; (4) an accurate treatment of the photoionization structure of absorbers, which enters in the calculation of the helium continuum opacity and recombination emissivity; and (5) the UV emission from star-forming galaxies at all redshifts. We provide tables of the predicted H I and He II photoionization and photoheating rates for use, e.g., in cosmological hydrodynamics simulations of the Ly? forest and a new metallicity-dependent calibration to the UV luminosity density-star formation rate density relation. A "minimal cosmic reionization model" is also presented in which the galaxy UV emissivity traces recent determinations of the cosmic history of star formation, the luminosity-weighted escape fraction of hydrogen-ionizing radiation increases rapidly with look-back time, the clumping factor of the high-redshift intergalactic medium evolves following the results of hydrodynamic simulations, and Population III stars and miniquasars make a negligible contribution to the metagalactic flux. The model provides a good fit to the hydrogen-ionization rates inferred from flux decrement and proximity effect measurements, predicts that cosmological H II (He III) regions overlap at redshift 6.7 (2.8), and yields an optical depth to Thomson scattering, ?es = 0.084 that is in agreement with Wilkinson Microwave Anisotropy Probe results. Our new background intensities and spectra are sensitive to a number of poorly determined input parameters and suffer from various degeneracies. Their predictive power should be constantly tested against new observations. We are therefore making our redshift-dependent UV/X emissivities and CUBA outputs freely available for public use at http://www.ucolick.org/~pmadau/CUBA.

Haardt, Francesco; Madau, Piero

2012-02-01

119

Surviving the Cold  

MedlinePLUS Videos and Cool Tools

... HealthDay January 31, 2014 Related MedlinePlus Pages Frostbite Hypothermia Winter Weather Emergencies Transcript Millions of Americans are ... dangerous cold-related complications such as frostbite or hypothermia. Luckily, protection can be found in just a ...

120

Cold Weather Aerostat Study.  

National Technical Information Service (NTIS)

Aerostats are being considered for application in cold weather regions. A review of aerostat flight experience to date was made to determine the limitations of the current technology. Areas for improvements and modifications to extend the aerostat system ...

R. L. Ashford

1982-01-01

121

Cold hardiness in molluscs  

NASA Astrophysics Data System (ADS)

Molluscs inhabit all types of environments: seawater, intertidal zone, freshwater and land, and of course may have to deal with subzero temperatures. Ectotherm animals survive cold conditions by avoiding it by extensive supercooling (freezing avoidant species) or by bearing the freezing of their extracellular body fluids (freezing tolerant species). Although some studies on cold hardiness are available for intertidal molluscs, they are scarce for freshwater and terrestrial ones. Molluscs often exhibit intermediary levels of cold hardiness, with a moderate or low ability to supercool and a limited survival to the freezing of their tissues. Several factors could be involved: their dependence on water, their ability to enter dormancy, the probability of inoculative freezing in their environment, etc. Size is an important parameter in the development of cold hardiness abilities: it influences supercooling ability in land snails, which are rather freezing avoidant and survival to ice formation in intertidal organisms, which generally tolerate freezing.

Ansart, Armelle; Vernon, Philippe

2003-05-01

122

Aerostat Cold Weather Study.  

National Technical Information Service (NTIS)

The arctic environment and its potential impact on Aerostat design and operations are discussed. Predictive meteorological resources available are summarized. Results of previous Aerostat operations in cold climates are reviewed and potential solutions di...

D. L. Kane

1989-01-01

123

Vitamin C and colds  

MedlinePLUS

Douglas RM, Hemilä H, Chalker E, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev . 2007 Jul 18;(3):CD000980. Kilgore D. Common respiratory diseases. Prim ...

124

Cold and Cough Medicines  

MedlinePLUS

... or cough symptoms? Besides drinking plenty of fluids and getting plenty of rest, you may want to take medicines. There are lots of different cold and cough medicines, and they do different things. Nasal ...

125

[Study of new blended chemical absorbents to absorb CO2].  

PubMed

Three kinds of blended absorbents were investigated on bench-scale experimental bench according to absorption rate and regeneration grade to select a reasonable additive concentration. The results show that, among methyldiethanolamine (MDEA) and piperazine (PZ) mixtures, comparing MDEA : PZ = 1 : 0.4 (m : m) with MDEA : PZ = 1 : 0.2 (m : m), the absorption rate is increased by about 70% at 0.2 mol x mol(-1). When regeneration lasting for 40 min, regeneration grade of blended absorbents with PZ concentration of 0.2, 0.4, and 0.8 is decreased to 83.06%, 77.77% and 76.67% respectively while 91.04% for PZ concentration of 0. MDEA : PZ = 1 : 0.4(m : m) is a suitable ratio for MDEA/PZ mixtures as absorption and regeneration properties of the blended absorbents are all improved. The aqueous blends with 10% primary amines and 2% tertiary amines could keep high CO2 absorption rate, and lower regeneration energy consumption. Adding 2% 2-Amino-2-methyl-1-propanol (AMP) to 10% diethanolamine (DEA), the blended amine solvents have an advantage in absorption and regeneration properties over other DEA/AMP mixtures. Blended solvents, which consist of a mixture of primary amines with a small amount of tertiary amines, have the highest absorption rate among the three. And mixed absorbents of secondary amines and a small amount of sterically hindered amines have the best regeneration property. To combine absorption and regeneration properties, blends with medium activator addition to tertiary amines are competitive. PMID:18290495

Wang, Jin-Lian; Fang, Meng-Xiang; Yan, Shui-Ping; Luo, Zhong-Yang; Cen, Ke-Fa

2007-11-01

126

Cyanobacteria in Cold Ecosystems  

Microsoft Academic Search

Perennially cold environments in which temperatures remain below 5°C are common throughout the biosphere (Margesin and Häggblom\\u000a 2007). In these habitats, the persistent cold temperatures are often accompanied by freeze—thaw cycles, extreme fluctuations\\u000a in irradiance (including ultraviolet radiation), and large variations in nutrient supply and salinity. As a result of these\\u000a constraints, polar and alpine environments contain a reduced biodiversity,

Frédéric Zakhia; Anne-Dorothee Jungblut; Arnaud Taton; Warwick F. Vincent; Annick Wilmotte

127

Teaching in a Cold Environment.  

ERIC Educational Resources Information Center

Designed to help teachers deal with students in a cold environment, this article explains cold physiology and fundamental laws of heat; describes 14 common cold injuries and their current treatment; and lists a number of useful teaching techniques for cold environments. (SB)

Ewert, Alan

1979-01-01

128

PT-symmetric laser absorber  

NASA Astrophysics Data System (ADS)

In a recent work, Y. D. Chong [Phys. Rev. Lett.0031-900710.1103/PhysRevLett.105.053901 105, 053901 (2010)] proposed the idea of a coherent perfect absorber (CPA) as the time-reversed counterpart of a laser, in which a purely incoming radiation pattern is completely absorbed by a lossy medium. The optical medium that realizes CPA is obtained by reversing the gain with absorption, and thus it generally differs from the lasing medium. Here it is shown that a laser with an optical medium that satisfies the parity-time (PT) symmetry condition ?(-r)=?*(r) for the dielectric constant behaves simultaneously as a laser oscillator (i.e., it can emit outgoing coherent waves) and as a CPA (i.e., it can fully absorb incoming coherent waves with appropriate amplitudes and phases). Such a device can thus be referred to as a PT-symmetric CPA laser. The general amplification or absorption features of the PT CPA laser below lasing threshold driven by two fields are determined.

Longhi, Stefano

2010-09-01

129

Multiband Metamaterial Absorber at Terahertz Frequencies  

NASA Astrophysics Data System (ADS)

We propose a multi-band metamaterial absorber operating at terahertz frequencies. The design, characterization, and theoretical calculation of the high performance metamaterial absorber are reported. The multi-band metamaterial absorber consists of two metallic layers separated by a dielectric spacer. Theoretical and simulated results show that the metamaterial absorber has four distinct absorption points at frequencies 0.57 THz, 1.03 THz, 1.44 THz and 1.89 THz, with the absorption rates of 99.9%, 90.3%, 83.0%, 96.1%, respectively. Two single band metamaterial absorbers and a dual band metamaterial absorber on the top layer are designed. Some multi-band absorbers can be designed by virtue of combining some single band absorbers. The multiple-reflection theory is used to explain the absorption mechanism of our investigated structures.

Xu, Zong-Cheng; Gao, Run-Mei; Ding, Chun-Feng; Zhang, Ya-Ting; Yao, Jian-Quan

2014-05-01

130

Neutron Mössbauer effect and the cold fusion in inhomogeneous materials  

Microsoft Academic Search

Summary  In relation with the trapped-neutron catalized model (TNCF model) to explain the Cold Fusion phenomenon, the neutron Mössbauer\\u000a effect is proposed to trap neutrons in a crystal composed of nuclei which can absorb a neutron resonantly to form an excited\\u000a state of an isotope. This mechanism of neutron trapping depends on the distribution of the protons (and\\/or deuterons) in the

H. Kozima

1994-01-01

131

Cold sea survival.  

NASA Technical Reports Server (NTRS)

Two prototype three-man life rafts were evaluated during the winter months in Arctic waters off Kodiak Island, Alaska, to assess potential survival problems and determine tolerance limits. Each raft incorporated thermal characteristics specifically designed for cold water. Water and air temperatures varied from 0 to +2 C and -5 to +4 C respectively. All subjects were removed upon reaching subjective tolerance. The results showed that none of the clothing assemblies was adequate to maintain a person in comfort even with dry boarding. No significant biochemical shifts in the blood or urine were found. The TUL raft was found to be superior in its thermal characteristics and afforded better subject protection. General tolerance for cold water immersion, wet and dry, and cold water raft exposures are depicted graphically, based on previously reported data.

Veghte, J. H.

1972-01-01

132

An introduction to Radar Absorbent Materials (RAM)  

Microsoft Academic Search

The electromagnetic principles of radar absorbent materials are summarized. The fundamental theory of electromagnetic wave propagation in media and at the interfaces between different media is reviewed, and approaches to absorber design are described. The types of materials required and the techniques for measuring their electromagnetic properties and the performance of the finished absorber are outlined. A means of designing

P. G. Lederer

1986-01-01

133

Waveguide characterization of flexible absorbing material  

Microsoft Academic Search

Among the materials with adequate performance to be used as radar absorbing material (RAM), the conducting polymers have been under intensive study due to their excellent potential for application in electromagnetic interference and microwave absorption areas, replacing conventional absorbing materials. The aim of this work is to present electromagnetic characterization of the flexible radar absorbing material at microwave frequency range

L. C. Folgueras; R. Faez; M. C. Rezende

2003-01-01

134

Optimization of ramified absorber networks doing desalination  

Microsoft Academic Search

An iterated function system is used to generate fractal-like ramified graph networks of absorbers, which are optimized for desalination performance. The diffusion equation is solved for the boundary case of constant pressure difference at the absorbers and a constant ambient salt concentration far from the absorbers, while constraining both the total length of the network and the total area of

Martin S. Singleton; Gregor Heiss; Alfred Hübler

2011-01-01

135

Electromagnetic scattering by pyramidal and wedge absorber  

Microsoft Academic Search

Electromagnetic scattering from pyramidal and wedge absorbers used to line the walls of modern anechoic chambers is measured and compared with theoretically predicted values. The theoretical performance for various angles of incidence is studied. It is shown that a pyramidal absorber scatters electromagnetic energy more as a random rough surface does. The apparent reflection coefficient from an absorber wall illuminated

Brian T. Dewitt; Walter D. Burnside

1988-01-01

136

Acral coldness in migraineurs.  

PubMed

In search for new biomarkers of vascular disturbances accompanying migraine, we compared the facial and hand skin temperatures in 41 women, including 12 migraine patients during the headache-free period and 29 healthy controls. Compared to the controls, the acral skin temperatures were lower in migraineurs, especially in those with right-sided headache. Our findings suggest that migraine is associated with a peripheral coldness possibly due to abnormal autonomic vascular control. The cold nose and hands may represent easily assessable biomarkers of these disorders. PMID:24080404

Zaproudina, Nina; Lipponen, Jukka A; Karjalainen, Pasi A; Kamshilin, Alexei A; Giniatullin, Rashid; Närhi, Matti

2014-02-01

137

Cold Dark Matter  

NASA Astrophysics Data System (ADS)

Motivated by inflation, the theory of big-bang nucleosynthesis, and the quest for a deeper understanding of fundamental forces and particles, a paradigm for the development of structure in the universe has evolved. It holds that most of the matter exists in the form of slowly moving elementary particles left over from the earliest moments--cold dark matter-and that the small density inhomogeneities that seed structure formation arose from quantum fluctuations around 10-34 seconds after the big bang. A flood of observations, from determinations of the Hubble constant to measurements of the anisotropy of cosmic background radiation, are now testing the cold dark matter paradigm.

Dodelson, Scott; Gates, Evalyn I.; Turner, Michael S.

1996-10-01

138

Graphene saturable absorbers for VECSELs  

NASA Astrophysics Data System (ADS)

We report mode-locking of an optically pumped VECSEL using a graphene-based saturable absorber mirror (GSAM). Self-starting and stable modelocked operation is demonstrated with 473 fs pulses at 1.5 GHz repetition rate and 949 nm center wavelength. Wavelength tuning is achieved over a 46 nm bandwidth. We discuss the mirror design, the fabrication of the GSAMs, and give an outlook on further optimization of the design, including dielectric top coatings to protect the graphene and to increase the flexibility in the design.

Wittwer, V. J.; Zaugg, C. A.; Sun, Z.; Popa, D.; Milana, S.; Kulmala, T. S.; Sundaram, R. S.; Mangold, M.; Golling, M.; Lee, Y.; Ahn, J. H.; Keller, U.; Ferrari, A. C.

2014-03-01

139

Porcelain enamel neutron absorbing material  

DOEpatents

A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

Iverson, Daniel C. (Aiken, SC)

1990-01-01

140

Experiments on a bubble absorber  

SciTech Connect

Experiments are carried out on a bubble absorber, operating as part of a vapor absorption refrigeration system working with HCFC22-DMF to obtain heat and mass transfer and pressure drop data. The results are evaluated to obtain the dependence of absorption process on different parameters. Experimental data are compared with the numerical correlation relating Sherwood number., Reynolds number, Schmidt number and length to diameter ratio developed earlier by the authors. Also the experimental pressure drop is compared with the pressure drop obtained from other well known classical correlations and the numerical model.

Sujatha, K.S.; Mani, A.; Murthy, S.S.

1999-10-01

141

Mulitlayered Nanostructured Broad Band Absorber  

NASA Astrophysics Data System (ADS)

Wasted energy in the form of heat is perhaps the largest source of lost energy making many power systems inefficient. Systems designed to convert heat into useful energy need a method of collecting the heat. We previously described a multilayer design with successive thin metallic and dielectric (non-metal and transparent) layers, where each successive metallic layer absorbs a small fraction of the radiation. However, the regular thickness of the dielectric layer causes reflection peaks, or regions where no absorption occurs. In this work we describe a similar design where we eliminated the undesirable reflection peaks using varying thicknesses of the dielectric layer.

Corrigan, Timothy; Ide, Benjamin

2013-03-01

142

Porcelain enamel neutron absorbing material  

DOEpatents

A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compound of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved. 2 figs.

Iverson, D.C.

1987-11-20

143

Graphene based salisbury screen for terahertz absorber  

NASA Astrophysics Data System (ADS)

A graphene-based, multiband absorber operating in terahertz (THz) frequency range was demonstrated. Graphene film was transferred onto the top of a flexible polymer substrate backed with a gold reflector. The graphene acts as a resistive film that partially attenuates and reflects THz waves. The destructive interference between THz waves reflected from graphene and backside reflector gives rise to perfect absorbance at multiple frequencies. To enhance the absorbance on/off ratio (AR), the conductivity of graphene was varied using a chemical doping method. The resulting p-doped, graphene-based THz absorber exhibited absorbance at maxima and AR higher than 0.95 and 25 dB, respectively.

Min Woo, Jeong; Kim, Min-Sik; Woong Kim, Hyun; Jang, Jae-Hyung

2014-02-01

144

Simulation studies on R134a—DMAC based half effect absorption cold storage systems  

Microsoft Academic Search

This paper presents simulation studies conducted on a half effect vapour absorption cycle using R134a-DMAC as the refrigerant-absorbent pair with low temperature heat sources for cold storage applications. The intermediate pressure of the cycle has been optimized for maximum COP. The effects of the temperatures of the evaporator, condenser, absorber and generator on the COP of the cycle have also

S. Arivazhagan; S. N. Murugesan; R. Saravanan; S. Renganarayanan

2005-01-01

145

Titanium Cold Spray Coatings  

NASA Astrophysics Data System (ADS)

Titanium Cold Spray Coatings Cold Spray is an emerging technology used for the deposition of coatings for many industries including aerospace. This technique allows the deposition of metallic materials at low temper-atures below their melting point. The aim of this research was to develop a test technique that can measure the degree to which a cold spray coating achieves mechanical properties similar to a traditional bulk material. Vickers hardness testing and nanoindentation were used as micro-and nano-scale measurement techniques to characterize the mechanical properties of titanium coatings, deposited at different deposition conditions, and bulk Ti. The mechanical properties of bulk titanium and titanium coatings were measured over a range of length scales, with the indentation size effect examined with Meyer's law. Hardness measurements are shown to be affected by material porosity, microstructure and coating particle bonding mechanism. Hard-ness measurements showed that Ti coatings deposited at higher gas pressures and temperatures demonstrate an indentation load response similar to bulk Ti. Key words: titanium, cold spray, Vickers hardness, nanoindentation, indentation size effect, microstructure, mechanical properties

Ajaja, Jihane; Goldbaum, Dina; Chromik, Richard; Yue, Stephen; Rezaeian, Ahmad; Wong, Wilson; Irissou, Eric; Legoux, Jean-Gabriel

146

Cold spray nozzle design  

DOEpatents

A nozzle for use in a cold spray technique is described. The nozzle has a passageway for spraying a powder material, the passageway having a converging section and a diverging section, and at least the diverging section being formed from polybenzimidazole. In one embodiment of the nozzle, the converging section is also formed from polybenzimidazole.

Haynes, Jeffrey D. (Stuart, FL) [Stuart, FL; Sanders, Stuart A. (Palm Beach Gardens, FL) [Palm Beach Gardens, FL

2009-06-09

147

Tumor Cold Ischemia  

Cancer.gov

In a recently published manuscript in the journal of Molecular and Cellular Proteomics, researchers from the National Cancer Institutes (NCI) Clinical Proteomic Tumor Analysis Consortium (CPTAC) investigated the effect of cold ischemia on the proteome of fresh frozen tumors.

148

5 Ultra Cold Neutrons  

Microsoft Academic Search

At the Paul Scherrer Institut (PSI) a new source of ultra cold neutrons (UCN) will be con- structed with the goal to improve the sensitivity to the neutron electric dipole moment (nEDM), which is sensitive to possible contributions from new physics. In addition the neu- tron decay parameters such as its life time may be studied more accurately. Presently, we

P. Fierlinger; S. Heule; U. Straumann

149

Cold Facts about Viruses.  

ERIC Educational Resources Information Center

Provides ways for students to demonstrate their understanding of scientific concepts and skills. Describes a mini-unit around the cold in which students can relate humans to viruses. Includes activities and a modified simulation that provides questions to guide students. Discusses ways that allows students to apply prior knowledge, take ownership…

Pea, Celeste; Sterling, Donna R.

2002-01-01

150

Cold War Propaganda.  

ERIC Educational Resources Information Center

Briefly discusses the development of Cold War propaganda in the United States, Canada, and the USSR after 1947. Presents two movie reviews and a Canadian magazine advertisement of the period which illustrate the harshness of propaganda used by both sides in the immediate postwar years. (GEA)

Bennett, Paul W.

1988-01-01

151

Cold Injury -- Frostbite.  

National Technical Information Service (NTIS)

There is no good way to treat a frostbitten extremity. At best, the physican currently can only avoid additional damage by overly vigorous treatment. In civilian practice the problem is of limited importance occurring primarily in those exposed to cold wh...

1982-01-01

152

Koldstartsanalyse. (Cold start analysis).  

National Technical Information Service (NTIS)

During the period in which a petrol-driven private car is driven with a cold engine, it uses a richer petrol/air mixture in order to overcome carburation difficulties in the inlet manifold. This results in higher emission. With or without catalytic conver...

H. C. Thorsen H. Bendtsen

1994-01-01

153

Catching a Cold  

NSDL National Science Digital Library

The purpose of this assessment probe is to elicit students' ideas about infectious disease. The probe is designed to find out whether students use the germ theory to explain what causes an infectious disease like the common cold. This free selection includes the Preface, Introduction, Table of Contents, and the Index.

Tugel, Joyce; Keeley, Page

2009-03-01

154

How Does Hot and Cold Gas Interact in Galaxies?  

NASA Astrophysics Data System (ADS)

Sa galaxies have roughly equal amounts of hot and cold gas, yet little is known about the interaction between the two phases. It is possible that the gas is thermally coupled, with cold gas cooling hot gas where the two phases interface. This would lead to a softening of the X-ray spectrum in the area of overlap. Alternatively, the phases could be thermally isolated, so that the cold gas in front of the hot gas absorbs soft X-rays behind it. We propose to observe two galaxies with unusual HI distributions to search for the interaction between the two phases. We will verify whether the hot gas fills the holes in the HI distribution. We will also investigate the lack of very luminous LMXBs in spiral bulges, and determine the luminosity function of the LMXBs that do exist in the bulges.

Irwin, Jimmy

2003-09-01

155

The Interaction of Hot and Cold Gas in Galaxies  

NASA Astrophysics Data System (ADS)

Sa galaxies have roughly equal amounts of hot and cold gas, yet little is known about the interaction between the two phases. It is possible that the gas is thermally coupled, with cold gas cooling hot gas where the two phases interface. This would lead to a softening of the X-ray spectrum in the area of overlap. Alternatively, the phases could be thermally isolated, so that the cold gas in front of the hot gas absorbs soft X-rays behind it. We propose to observe three galaxies with unusual HI distributions to search for the interaction between the two phases. We will verify whether the hot gas fills the holes in the HI distribution. We will also investigate the lack of very luminous LMXBs in spiral bulges, and determine the luminosity function of the LMXBs that do exist in the bulges.

Irwin, Jimmy

2002-09-01

156

Cold Injury of Amputated Digits.  

National Technical Information Service (NTIS)

Patients who acquired an upper extremity nerve injury often complain about cold intolerance, reduced sensitivity and decreased task performance. This study tried to quantify these complaints and look in more detail at the thermal reaction to local cold ex...

U. Ahcan B. Luzar F. Bajrovic I. Mekjavic

2005-01-01

157

PHEV Cold Start Emissions Management.  

National Technical Information Service (NTIS)

Plug-in hybrid electric vehicles (PHEV) operate predominantly as electric vehicles (EV) with intermittent assist from the engine. As a consequence, the engine can be subjected to multiple cold start events. These cold start events have a significant impac...

2013-01-01

158

Protecting Workers from Cold Stress  

MedlinePLUS

... agriculture and construction. Common Types of Cold Stress Hypothermia • Normal body temperature (98.6°F) drops to ... When a Worker Suffers from Cold Stress For Hypothermia: • Call 911 immediately in an emergency. • To prevent ...

159

The origin of cold gas in giant elliptical galaxies and its role in fuelling radio-mode AGN feedback  

NASA Astrophysics Data System (ADS)

The nature and origin of the cold interstellar medium (ISM) in early-type galaxies are still a matter of debate, and understanding the role of this component in galaxy evolution and in fuelling the central supermassive black holes requires more observational constraints. Here, we present a multiwavelength study of the ISM in eight nearby, X-ray and optically bright, giant elliptical galaxies, all central dominant members of relatively low-mass groups. Using far-infrared spectral imaging with the Herschel Photodetector Array Camera & Spectrometer, we map the emission of cold gas in the cooling lines of [C II]?157 ?m, [O I] ?63 ?m and [O Ib] ?145 ?m. Additionally, we present H?+[N II] imaging of warm ionized gas with the Southern Astrophysical Research (SOAR) telescope, and a study of the thermodynamic structure of the hot X-ray emitting plasma with Chandra. All systems with extended H? emission in our sample (6/8 galaxies) display significant [C II] line emission indicating the presence of reservoirs of cold gas. This emission is cospatial with the optical H?+[N II] emitting nebulae and the lowest entropy soft X-ray emitting plasma. The entropy profiles of the hot galactic atmospheres show a clear dichotomy, with the systems displaying extended emission-line nebulae having lower entropies beyond r ? 1 kpc than the cold-gas-poor systems. We show that while the hot atmospheres of the cold-gas-poor galaxies are thermally stable outside of their innermost cores, the atmospheres of the cold-gas-rich systems are prone to cooling instabilities. This provides considerable weight to the argument that cold gas in giant ellipticals is produced chiefly by cooling from the hot phase. We show that cooling instabilities may develop more easily in rotating systems and discuss an alternative condition for thermal instability for this case. The hot atmospheres of cold-gas-rich galaxies display disturbed morphologies indicating that the accretion of clumpy multiphase gas in these systems may result in variable power output of the AGN jets, potentially triggering sporadic, larger outbursts. In the two cold-gas-poor, X-ray morphologically relaxed galaxies of our sample, NGC 1399 and NGC 4472, powerful AGN outbursts may have destroyed or removed most of the cold gas from the cores, allowing the jets to propagate and deposit most of their energy further out, increasing the entropy of the hot galactic atmospheres and leaving their cores relatively undisturbed.

Werner, N.; Oonk, J. B. R.; Sun, M.; Nulsen, P. E. J.; Allen, S. W.; Canning, R. E. A.; Simionescu, A.; Hoffer, A.; Connor, T.; Donahue, M.; Edge, A. C.; Fabian, A. C.; von der Linden, A.; Reynolds, C. S.; Ruszkowski, M.

2014-04-01

160

Oxalate: Effect on calcium absorbability  

SciTech Connect

Absorption of calcium from intrinsically labeled Ca oxalate was measured in 18 normal women and compared with absorption of Ca from milk in these same subjects, both when the test substances were ingested in separate meals and when ingested together. Fractional Ca absorption from oxalate averaged 0.100 +/- 0.043 when ingested alone and 0.140 +/- 0.063 when ingested together with milk. Absorption was, as expected, substantially lower than absorption from milk (0.358 +/- 0.113). Nevertheless Ca oxalate absorbability in these women was higher than we had previously found for spinach Ca. When milk and Ca oxalate were ingested together, there was no interference of oxalate in milk Ca absorption and no evidence of tracer exchange between the two labeled Ca species.

Heaney, R.P.; Weaver, C.M. (Creighton Univ., Omaha, NE (USA))

1989-10-01

161

Optimum orientation of absorber plates  

SciTech Connect

Long-term analyses are presented to predict the optimum tilt angle of an absorber plate at any surface azimuth angle {gamma}. The analyses include the effects of number of glass covers, latitude angle, monthly average clearness index, month, and ground reflectivity. The effects of each of these parameters on the optimum tilt of a south-facing surface are studied. Two numerical correlations, for ground reflectivity equal 0.2 and 0.7, are developed to predict the monthly optimum tilt of a surface. The two correlations are used to predict the optimum tilt of a surface over any specified period of time that extends from one month up to several months or a year. The analyses are also extended to predict the optimum tilt angle and azimuth angles of surfaces exposed to shading by surrounding objects. Illustrative examples are presented to demonstrate the application of the analyses.

Elsayed, M.M. (King Abdulaziz Univ., Jeddah (Saudi Arabia))

1989-01-01

162

Remedies for Common Cold Symptoms  

PubMed Central

Individuals suffering from intolerable symptoms of the common cold can now be advised of safe and effective products for symptomatic relief. This article describes and discusses four categories of drugs used to treat the common cold. To simplify the product selection process for family physicians, suggestions are included for possible ingredients for treatments of specific cold symptoms.

Miller, Penny F.

1991-01-01

163

Modeling the Absorbing Aerosol Index  

NASA Technical Reports Server (NTRS)

We propose a scheme to model the absorbing aerosol index and improve the biomass carbon inventories by optimizing the difference between TOMS aerosol index (AI) and modeled AI with an inverse model. Two absorbing aerosol types are considered, including biomass carbon and mineral dust. A priori biomass carbon source was generated by Liousse et al [1996]. Mineral dust emission is parameterized according to surface wind and soil moisture using the method developed by Ginoux [2000]. In this initial study, the coupled CCM1 and GRANTOUR model was used to determine the aerosol spatial and temporal distribution. With modeled aerosol concentrations and optical properties, we calculate the radiance at the top of the atmosphere at 340 nm and 380 nm with a radiative transfer model. The contrast of radiance at these two wavelengths will be used to calculate AI. Then we compare the modeled AI with TOMS AI. This paper reports our initial modeling for AI and its comparison with TOMS Nimbus 7 AI. For our follow-on project we will model the global AI with aerosol spatial and temporal distribution recomputed from the IMPACT model and DAO GEOS-1 meteorology fields. Then we will build an inverse model, which applies a Bayesian inverse technique to optimize the agreement of between model and observational data. The inverse model will tune the biomass burning source strength to reduce the difference between modelled AI and TOMS AI. Further simulations with a posteriori biomass carbon sources from the inverse model will be carried out. Results will be compared to available observations such as surface concentration and aerosol optical depth.

Penner, Joyce; Zhang, Sophia

2003-01-01

164

Ultra-strong Mg II absorbers as a signature of cool intragroup gas  

NASA Astrophysics Data System (ADS)

We present the results of a spectroscopic survey of galaxies in the vicinity of an ultra-strong Mg II ??2786, 2803 absorber of rest-frame absorption equivalent width Wr(2796) = 4.2 Å at z = 0.5624. This absorber was originally found at projected separation ? = 246 kpc of a luminous red galaxy (LRG) at z = 0.5604. Inamori-Magellan Areal Camera and Spectrograph (IMAC) spectroscopy has revealed two galaxies at ? < 60 kpc (z = 0.5623 and z = 0.5621) and a third one at ? = 209 kpc (z = 0.5623) near the redshift of the absorber. These findings indicate that the absorbing gas resides in a group environment. Combining Sloan Digital Sky Survey (SDSS) broad-band photometry with additional B-, Ks-band images and optical spectroscopy, we perform a stellar population synthesis analysis of the group members to characterize their star formation histories, on-going star formation rates (SFR), and stellar masses. We find that the two group members at ? < 60 kpc are best characterized by old stellar populations (>1 Gyr) and little on-going star formation activity (SFR < 2.9 M? yr-1), while the third object at ? = 209 kpc exhibits [O II]- and continuum-derived SFR consistent with SFR > 3.0 M? yr-1. Including the two ultra-strong Mg II absorbers analysed by Nestor et al., this is the third ultra-strong Mg II absorber for which a detailed study of the galactic environment is available. All three absorbers are found in galaxy groups. We examine different physical mechanisms giving rise to the absorbing gas including starburst-driven outflows, cold filaments, extended rotating discs and stripped gas. We argue that the large equivalent width observed in these absorbers is more likely due to the gas dynamics of the intragroup medium rather than driven by starburst outflows.

Gauthier, Jean-René

2013-06-01

165

Radial cold trap  

DOEpatents

The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume.

Grundy, Brian R. (Greensburg, PA)

1981-01-01

166

Radial cold trap  

DOEpatents

The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume. 2 figs.

Grundy, B.R.

1981-09-29

167

WISPy cold dark matter  

NASA Astrophysics Data System (ADS)

Very weakly interacting slim particles (WISPs), such as axion-like particles (ALPs) or hidden photons (HPs), may be non-thermally produced via the misalignment mechanism in the early universe and survive as a cold dark matter population until today. We find that, both for ALPs and HPs whose dominant interactions with the standard model arise from couplings to photons, a huge region in the parameter spaces spanned by photon coupling and ALP or HP mass can give rise to the observed cold dark matter. Remarkably, a large region of this parameter space coincides with that predicted in well motivated models of fundamental physics. A wide range of experimental searches — exploiting haloscopes (direct dark matter searches exploiting microwave cavities), helioscopes (searches for solar ALPs or HPs), or light-shining-through-a-wall techniques — can probe large parts of this parameter space in the foreseeable future.

Arias, Paola; Cadamuro, Davide; Goodsell, Mark; Jaeckel, Joerg; Redondo, Javier; Ringwald, Andreas

2012-06-01

168

Cold nuclear fusion  

NASA Astrophysics Data System (ADS)

Recent accelerator experiments on fusion of various elements have clearly demonstrated that the effective cross-sections of these reactions depend on what material the target particle is placed in. In these experiments, there was a significant increase in the probability of interaction when target nuclei are imbedded in a conducting crystal or are a part of it. These experiments open a new perspective on the problem of so-called cold nuclear fusion.

Tsyganov, E. N.

2012-02-01

169

Cold nuclear fusion  

Microsoft Academic Search

The possibility that negative muons could catalyze nuclear fusion was suggested on theoretical grounds by F.C. Frank and A.D. Sakharov in the late 1940s; the first experimental observations of the process followed serendipitously a decade later, in experiments at Berkeley by L.W. Alvarez. The fastest mechanism for muon-catalyzed, or 'cold' fusion, was suggested by Vesman (1967); it depends on a

Johann Rafelski; Steven E. Jones

1987-01-01

170

Teachers Debate Cold Fusion  

NASA Astrophysics Data System (ADS)

What follows is a collection of messages about cold fusion from teachers. The messages were posted on the internet discussion list, Phys-L, or were sent to me in private. They illustrate a wide range of opinion. Phys-L is a list dedicated to learning and teaching physics with 700 subscribers from over 35 countries, the majority of whom are physics educators. <>.

Kowalski, Ludwik

2005-12-01

171

A hybrid active-passive sound absorber  

NASA Astrophysics Data System (ADS)

The structure of an active-passive sound absorber is considered, and issues concerning analytic and experimental studies of the efficiency of sound absorber operation are discussed. A description is presented of both the passive part of the hybrid sound absorber and the active system incorporated in it. A test bench constructed on the basis of a low-frequency acoustic interferometer for measuring the sound absorption coefficient and the input impedance of the hybrid sound absorber under normally incident sound waves is described. An algorithm is proposed for controlling the active system of the hybrid sound absorber. The operation efficiency of the active system controlled by the proposed algorithm is analytically investigated. The results obtained from the experimental study of the hybrid active-passive sound absorber on the measuring test bench are presented.

Belov, V. D.; Migun, Yu. G.; Orlov, A. I.

2012-07-01

172

Magnetic field effects on microwave absorbing materials  

NASA Technical Reports Server (NTRS)

The objective of this program was to gather information to formulate a microwave absorber that can work in the presence of strong constant direct current (DC) magnetic fields. The program was conducted in four steps. The first step was to investigate the electrical and magnetic properties of magnetic and ferrite microwave absorbers in the presence of strong magnetic fields. This included both experimental measurements and a literature survey of properties that may be applicable to finding an appropriate absorbing material. The second step was to identify those material properties that will produce desirable absorptive properties in the presence of intense magnetic fields and determine the range of magnetic field in which the absorbers remain effective. The third step was to establish ferrite absorber designs that will produce low reflection and adequate absorption in the presence of intense inhomogeneous static magnetic fields. The fourth and final step was to prepare and test samples of such magnetic microwave absorbers if such designs seem practical.

Goldberg, Ira; Hollingsworth, Charles S.; Mckinney, Ted M.

1991-01-01

173

Electromagnetic scattering by pyramidal and wedge absorber  

NASA Technical Reports Server (NTRS)

Electromagnetic scattering from pyramidal and wedge absorbers used to line the walls of modern anechoic chambers is measured and compared with theoretically predicted values. The theoretical performance for various angles of incidence is studied. It is shown that a pyramidal absorber scatters electromagnetic energy more as a random rough surface does. The apparent reflection coefficient from an absorber wall illuminated by a plane wave can be much less than the normal absorber specifications quoted by the manufacturer. For angles near grazing incidence, pyramidal absorbers give a large backscattered field from the pyramid side-faces or edges. The wedge absorber was found to give small backscattered fields for near-grazing incidence. Based on this study, some new guidelines for the design of anechoic chambers are advocated because the specular scattering models used at present do not appear valid for pyramids that are large compared to the wavelength.

Dewitt, Brian T.; Burnside, Walter D.

1988-01-01

174

Cold Drawn ERW Pipes with Superior Formability,  

National Technical Information Service (NTIS)

Cold drawn ERW pipes have been applied in various fields. Cold drawn pipes show recrystallized microstructures when they are annealed for softening. Cold drawn ERW pipes sometimes show a difficulty in formability during cold working of expanding, swaging ...

T. Adaniya T. Takamura T. Meada F. Nishimura M. Morimoto

1988-01-01

175

Cold Stowage Flight Systems  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) provides a test bed for researchers to perform science experiments in a variety of fields, including human research, life sciences, and space medicine. Many of the experiments being conducted today require science samples to be stored and transported in a temperature controlled environment. NASA provides several systems which aide researchers in preserving their science. On orbit systems provided by NASA include the Minus Eighty Laboratory freezer for ISS (MELFI), Microgravity Experiment Research Locker Incubator (MERLIN), and Glacier. These freezers use different technologies to provide rapid cooling and cold stowage at different temperature levels on board ISS. Systems available to researchers during transportation to and from ISS are MERLIN, Glacier, and Coldbag. Coldbag is a passive cold stowage system that uses phase change materials. Details of these current technologies will be provided along with operational experience gained to date. With shuttle retirement looming, NASA has protected the capability to provide a temperature controlled environment during transportation to and from the ISS with the use of Glacier and Coldbags, which are compatible with future commercial vehicles including SpaceX's Dragon Capsule, and Orbital s Cygnus vehicle. This paper will discuss the capability of the current cold stowage hardware and how it may continue to support NASA s mission on ISS and in future exploration missions.

Campana, Sharon

2010-01-01

176

Cold Stowage Flight Systems  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) provides a test bed for researchers to perform science experiments in a variety of fields, including human research, life sciences, and space medicine. Many of the experiments being conducted today require science samples to be stored and transported in a temperature controlled environment. NASA provides several systems which aid researchers in preserving their science. On orbit systems provided by NASA include the Minus Eighty Laboratory freezer for ISS (MELFI), Microgravity Experiment Research Locker Incubator (MERLIN), and Glacier. These freezers use different technologies to provide rapid cooling and cold stowage at different temperature levels on board ISS. Systems available to researchers during transportation to and from ISS are MERLIN, Glacier, and Coldbag. Coldbag is a passive cold stowage system that uses phase change materials to maintain temperature. Details of these current technologies are provided along with operational experience gained to date. This paper discusses the capability of the current cold stowage hardware and how it may continue to support NASA s mission on ISS and in future exploration missions.

Campana, Sharon E.; Melendez, David T.

2011-01-01

177

Boron-copper neutron absorbing material and method of preparation  

DOEpatents

A composite, copper clad neutron absorbing material is comprised of copper powder and boron powder enriched with boron 10. The boron 10 content can reach over 30 percent by volume, permitting a very high level of neutron absorption. The copper clad product is also capable of being reduced to a thickness of 0.05 to 0.06 inches and curved to a radius of 2 to 3 inches, and can resist temperatures of 900.degree. C. A method of preparing the material includes the steps of compacting a boron-copper powder mixture and placing it in a copper cladding, restraining the clad assembly in a steel frame while it is hot rolled at 900.degree. C. with cross rolling, and removing the steel frame and further rolling the clad assembly at 650.degree. C. An additional sheet of copper can be soldered onto the clad assembly so that the finished sheet can be cold formed into curved shapes.

Wiencek, Thomas C. (Bolingbrook, IL); Domagala, Robert F. (Indian Head Park, IL); Thresh, Henry (Palos Hts., IL)

1991-01-01

178

ANL Advanced Photon Source crotch absorber design  

Microsoft Academic Search

The ANL 7 GeV Advanced Photon Source storage ring crotch absorber will be subjected to a very high photon loading power density, approximately 750 w\\/mm2 at normal incidence. To accommodate this high heat load, two designs are studied: a V-type compound angle absorber and a horizontally rotated plate absorber. For both model, thermal and structural analyses have been carried out

M. Choi; J. D. Gonczy; J. W. Howell; R. C. Niemann

1991-01-01

179

Nonlinear dynamic vibration absorbers with a saturation  

NASA Astrophysics Data System (ADS)

The behavior of a new type of nonlinear dynamic vibration absorber is studied. A distinctive characteristic of the proposed absorber is the impossibility to extend the system to infinity. The mathematical formulation is based on a finite extensibility nonlinear elastic potential to model the saturable nonlinearity. The absorber is attached to a single degree-of-freedom linear/nonlinear oscillator subjected to a periodic external excitation. In order to solve the equations of motion and to analyze the frequency-response curves, the method of averaging is used. The performance of the FENE absorber is evaluated considering a variation of the nonlinearity of the primary system, the damping and the linearized frequency of the absorber and the mass ratio. The numerical results show that the proposed absorber has a very good efficiency when the nonlinearity of the primary system increases. When compared with a cubic nonlinear absorber, for a large nonlinearity of the primary system, the FENE absorber shows a better effectiveness for the whole studied frequency range. A complete absence of quasi-periodic oscillations is also found for an appropriate selection of the parameters of the absorber. Finally, direct integrations of the equations of motion are performed to verify the accuracy of the proposed method.

Febbo, M.; Machado, S. P.

2013-03-01

180

Photoacoustic cavitation in spherical and cylindrical absorbers  

NASA Astrophysics Data System (ADS)

Photomechanical damage in absorbing regions or particles surrounded by a non-absorbing medium is investigated experimentally and theoretically. The damage mechanism is based on the generation of thermoelastic pressure by absorption of pulsed laser radiation under conditions of stress confinement. Principles of photoacoustic sound generation predict that the acoustic wave generated in a finite-size absorbing region must contain both compressive and tensile stresses. Time-resolved imaging experiments were performed to examine whether the tensile stress causes cavitation in absorbers of spherical or cylindrical shape. The samples were absorbing water droplets and gelatin cylinders suspended in oil. They were irradiated with 6-ns-long pulses from an optical parametric oscillator. Photoacoustic cavitation was observed near the center of the absorbers, even if the estimated temperature caused by absorption of the laser pulse did not exceed the boiling point. The experimental findings are supported by theoretical simulations that reveal strong tensile stress in the interior of the absorbers, near the center of symmetry. Tensile stress amplitudes depend on the shape of the absorber, the laser pulse duration, and the ratio of absorber size to optical absorption length. The photoacoustic damage mechanism has implications for the interaction of ns and sub-nslaser pulses with pigmented structures in biological tissue.

Paltauf, G.; Schmidt-Kloiber, H.

181

TPX/TFTR Neutral Beam energy absorbers  

SciTech Connect

The present beam energy absorbing surfaces on the TFTR Neutral Beams such as Ion Dumps, Calorimeters, beam defining apertures, and scrapers, are simple water cooled copper plates which wee designed to absorb (via their thermal inertia) the incident beam power for two seconds with a five minute coal down interval between pulses. These components are not capable of absorbing the anticipated beam power loading for 1000 second TPX pulses and will have to be replaced with an actively cooled design. While several actively cooled energy absorbing designs were considered,, the hypervapotron elements currently being used on the JET beamlines were chosen due to their lower cooling water demands and reliable performance on JET.

Dahlgren, F.; Wright, K.; Kamperschroer, J.; Grisham, L.; Lontai, L.; Peters, C.; VonHalle, A.

1993-11-01

182

Absorbent product and articles made therefrom  

NASA Technical Reports Server (NTRS)

A multilayer absorbent product for use in contact with the skin to absorb fluids is described. The product has a water pervious facing layer for contacting the skin, and a first fibrous wicking layer overlaying the water pervious layer. A first container section is defined by inner and outer layers of a water pervious wicking material in between a first absorbent mass and a second container section defined by inner and outer layers of a water pervious wicking material between what is disposed a second absorbent mass, and a liquid impermeable/gas permeable layer overlaying the second fibrous wicking layer.

Dawn, F. S.; Correale, J. V. (inventors)

1982-01-01

183

Device for absorbing mechanical shock  

DOEpatents

This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy-absorption capability.

Newlon, Charles E. (Knoxville, TN)

1980-01-01

184

Nonlinear absorbance effects in bacteriorhodopsin  

NASA Astrophysics Data System (ADS)

Bacteriorhodopsin (BR) is a protein found in the cell membrane wall of Halobacterium halobium and serves as a light-activated proton pump (i.e., the protein converts light energy into chemical energy). The chromophore (retinal) responsible for light absorption is located within a pocket of the opsin and is bound via a Schiff base to a lysine residue in the amino acid sequence. When BR is illuminated by a laser light flash, transient changes occur in the visible absorption spectrum of the protein -- i.e., the material is photochromic. The optical absorption changes are characterized by a series of photointermediates, with characteristic rise and fall times that range from less than a picosecond to more then 10 milliseconds. This photochromic property of BR makes it a useful material for optical devices. With an aim toward developing an optical switch for the Army, we are studying the transient absorption of nanosecond light pulses from a dye laser in the spectral region in which the absorbance of BR increases as light intensity increases. This nonlinear effect is wavelength-dependent and becomes a bleach in a different spectral window. The nonlinear absorption change is reversible.

Rayfield, George W.

1991-03-01

185

Skewed Frequency Selective Surface Absorber  

NASA Astrophysics Data System (ADS)

In this paper, a skewed Frequency Selective Surface (FSS) absorber based on cross-dipole elements is presented. The proposed FSS design provides good frequency stability for oblique incidences. It provides better absorption rate for 5-GHz WLAN frequency band and allow other communication bands to pass through it. Also, the absorption in the stop-band reduces multipath fading of additional WLAN signals which occurred due to the placement of conducting/reflecting FSS. The FSS design consists of two layers; first layer consists of conducting cross-dipole and second layer consists of resistive cross-dipole placed in-front of the first layer. The periodicity of both elements is same. Asymmetric property is applied to FSS elements by taking a reference of central element. This technique leads to achieve a maximum stability in the stop-band. Simulated results demonstrated that the proposed FSS design has a stable frequency response for 5-GHz frequency band for both horizontal (TE) and vertical (TM) polarizations when the incident wave angle varied from 0 0 to 45 0.

Rafique, Umair; Khan, M. Arif; Afzal, M. Tausif; Malik, Fahad; Qasim, Shahzaib

2012-12-01

186

Modal structure of centrifugal pendulum vibration absorber systems with multiple cyclically symmetric groups of absorbers  

NASA Astrophysics Data System (ADS)

This work studies the symmetry breaking effects on the vibration mode structure of centrifugal pendulum vibration absorber (CPVA) systems when multiple groups of absorbers are used. An absorber group is a set of equally spaced, identical absorbers. Absorbers within a group are cyclically symmetric while the entire system is asymmetric because the groups have no pre-defined relative angular spacing. One rotational and two translational degrees of freedom for the rotor and a single arclength degree of freedom for each absorber are considered in the planar model. The well-defined structure of the vibration modes is obtained by analytical and numerical investigations of the associated eigenvalue problem. This vibration mode structure is similar to that for CPVA systems with equally spaced, identical absorbers. Thus, the disrupted symmetry from multiple absorber groups does not destroy the vibration mode structure resulting from the cyclic symmetry within each group. The critical speeds and flutter instability of the system are investigated.

Shi, Chengzhi; Parker, Robert G.

2013-09-01

187

The two-sheet capacitive Jaumann absorber  

Microsoft Academic Search

Many Jaumann absorber designs rely on purely resistive sheets spaced ?\\/4 apart, and the designs are based on the requirement that the voltage reflection coefficient and its derivatives vanish at the center frequency. The thickness of the absorber can be reduced and its bandwidth considerably expanded if the sheets are allowed to have capacitive reactances in addition to pure resistance.

E. F. Knott; C. D. Lunden

1995-01-01

188

Topology optimization of energy-absorbing structures  

Microsoft Academic Search

This paper presents a method for and examples of topology optimization of energy absorption structures. The topology optimization problem is solved by using the elements as design variables. The sensitivity number of an element is derived from using an adjoint method to address two principal design parameters, namely absorbed energy per unit volume, e1, and absorbed energy ratio, e2. Filter

X Huang; Y M Xie; G Lu

2007-01-01

189

Development of Monofilar Rotor Hub Vibration Absorber.  

National Technical Information Service (NTIS)

A design and ground test program was conducted to study the performance of the monofilar absorber for vibration reduction on a four-bladed helicopter. A monofilar is a centrifugal tuned two degree-of-freedom rotor hub absorber that provides force attenuat...

J. Duh W. Miao

1983-01-01

190

Diffraction can mimic saturation in multiphoton absorbers  

NASA Astrophysics Data System (ADS)

Many traditional investigations of saturation in multiphoton absorbers with the z-scan method use an approximate analytical formula that assumes a steady-state approximation. Using a numerical simulation for Maxwell's equations for laser propagation including diffraction and coupled electron population dynamics, we show that the commonly used analytical formula for determining saturation in multiphoton absorbers is often incorrect, even when the sample thickness is only one diffraction length. Using published experimental data on an organic chromophore, we show that saturation, in fact, does not occur at the laser intensity values predicted for these two and three photon absorbers. We numerically fit the published experimental z-scan data and obtain new absorption coefficients for multiphoton absorbers that accurately reflect their intrinsic values. The new values are from three to ten times larger than the published values. Because multiphoton absorbers are being used more extensively in many applications such as optical limiter, medical diagnostics and two photon microscopy, it is important to have accurate values for the two and three-photon absorption coefficients. Knowing the real value of the multiphoton absorber coefficients, even for a single diffraction length, is therefore of the utmost importance. In particular, the laser intensity at which the absorber saturates can determine which absorber is useful for a particular application.

Potasek, M.; Parilov, E.; Walker, M.

2014-03-01

191

Analysis of absorbing times of quantum walks  

Microsoft Academic Search

Quantum walks are expected to provide useful algorithmic tools for quantum computation. This paper introduces absorbing probability and time of quantum walks and gives both numerical simulation results and theoretical analyses on Hadamard walks on the line and symmetric walks on the hypercube from the viewpoint of absorbing probability and time.

Tomohiro Yamasaki; Hirotada Kobayashi; Hiroshi Imai

2003-01-01

192

Modelling of magnetic radar absorbing composites  

Microsoft Academic Search

This paper addresses the modelling of radar absorbing composite layers with ferromagnetic inclusions. The radar absorbing properties of these layers are strongly determined by the effective permeability of the composite material. The applicability of mixing formulas is discussed to determine the effective permeability. Furthermore, the RF-frequency behaviour of ferromagnetic inclusions is described. The mixing formulas and the RF-frequency behaviour of

Harmen Schippers; Tomas Lundin; Jaap Heijstek

2010-01-01

193

The design of broadband radar absorbing surfaces  

Microsoft Academic Search

There has been a growing and widespread interest in radar absorbing material technology. As the name implies, radar absorbing materials or RAM's are coatings whose electric and magnetic properties have been selected to allow the absorption of microwave energy at discrete or broadband frequencies. In military applications low radar cross section (RCS) of a vehicle may be required in order

Go H. Suk

1990-01-01

194

Wideband thin resistive metamaterial radar absorbing screen  

Microsoft Academic Search

It has been demonstrated that two layer metamaterial Hilbert curve array constructed from low conductivity material can act as a thin wideband radar absorbing screen. The advantage of using Hilbert curve over traditional circuit analogue radar absorbing screen is the smaller unit cell size, resulting in reduced coupling to higher order Floquent modes and reduced diffraction effects, which in turn

A. Noor; Zhirun Hu; H. H. Ouslimani; A. Priou

2009-01-01

195

An application of metamaterials: Perfect absorbers  

NASA Astrophysics Data System (ADS)

We studied structures that describe the perfect-absorber effect by using different mechanisms. Firstly, we investigated the dependences of the reflectance and the absorbance of a metamaterial, as structure proposed by Landy et al. [Phys. Rev. Lett. 100, 207402 (2008)] on gap `g' of the structure at GHz frequencies. The value of the gap was obtained, which gives the maximum absorbance and the minimum reflectance. In addition, the change of geometry of the electric ring resonance as an I-shape made the reflectance disappear at the resonance frequency. A narrow-band peak of the perfect-absorber effect, which was enhanced to be greater than 99.5% at 13.5 GHz, was observed by using a multilayer model for the simplified absorber structure. Secondly, we investigated an absorber structure that includes two metal layers, periodic cut-wire bars at the front and a copper plane at the back, separated by a dielectric layer. The results showed that the absorbance and the resonance frequency of this structure strongly depended on the thickness and the length of the cut-wire bar, respectively. Base on these, we successfully designed a broad-band absorber structure by arranging cut-wire bars with different lengths appropriately in a "meta-atom".

Lee, Y. P.; Tuong, P. V.; Zheng, H. Y.; Rhee, J. Y.; Jang, W. H.

2012-04-01

196

SILVER-CADMIUM-INDIUM ABSORBER DEVELOPMENT  

Microsoft Academic Search

Development of an Ag--Cd--In alternate absorber section is described for ; Army Type SM reactors. The absorber material composition and the geometric ; configuration are described, and the nuclear and thermal analyses supporting this ; configuration are given. A detailed description of the manufacturing practice ; employed in fabricating the final design component is also included. (auth);

R. A. Shaw; R. L. Harris

1962-01-01

197

Pyro-adaptive impact energy absorber  

Microsoft Academic Search

The paper contains a proposal of energy dissipation density controlling in lightweight thinwalled structures by reducing their crushing stiffness during an impact process. For small scale laboratory experiments, low-energy-dissipation absorber was developed. Prismatic absorber made of thin lead sheets can dissipate the impact energy at two energy density levels. Moving the concept to the real steel or aluminum structures can

Marian Ostrowski; Paulius Griskevicius; Jan Holnicki-Szulc

198

Terahertz backscattering behavior of various absorbing materials  

Microsoft Academic Search

The Submillimeter-Wave Technology Laboratory (STL) at the University of Massachusetts Lowell has investigated the electromagnetic scattering behavior of various broadband absorbers. Several absorbing materials were tested in a compact radar range operating at a center frequency of 160 GHz. The polarimetric radar cross section was measured at elevation angles from 15° to 75°. In addition to the backscattering behavior, the

C. Wu; A. J. Gatesman; L. Deroeck; T. Horgan; R. H. Giles; W. E. Nixon

2009-01-01

199

Metallic tube type energy absorbers: A synopsis  

Microsoft Academic Search

This paper presents an overview of energy absorbers in the form of tubes in which the material used is predominantly mild steel and\\/or aluminium. A brief summary is also given of frusta type energy absorbers. The common modes of deformation such as lateral and axial compression, indentation and inversion are reviewed. Theoretical, numerical and experimental methods which help to understand

A. G. Olabi; Edmund Morris; M. S. J. Hashmi

2007-01-01

200

Highly efficient special sound absorbing solutions  

NASA Technical Reports Server (NTRS)

Highly efficient special sound absorbing structures with the following criteria are considered: (1) A distribution surface of the sound absorbing material greater than that of the building element on which the structure is placed; (2) The highest possible absorption coefficient in the widest possible frequency band; and (3) adaptability to different construction and aesthetic conditions.

Ionescu, M.; Petre-Lazar, S.

1974-01-01

201

Peregrinations on cold fusion  

SciTech Connect

Attention is focused on the possibility of resonance-enhanced deuteron Coulomb barrier penetration. Because of the many-body nature of the interactions of room-temperature deuterons diffusing through a lattice possessing deuterons in many of the interstitial positions, the diffusing deuterons can resonate on the atomic scale in the potential wells bounded by the ascending walls of adjacent Coulomb barriers and thereby penetrate the Coulomb barriers in a fashion vastly underestimated by two-body calculations in which wells for possible resonance are absent. Indeed, perhaps the lack of robust reproducibility in cold fusion originates from the narrowness of such transmission resonances. 4 refs., 1 fig.

Turner, L.

1989-01-01

202

An Absorbing Boundary Condition Based on Anechoic Absorber For EM Scattering Computation  

Microsoft Academic Search

A novel absorbing boundary condition (ABC), to be used with finite difference and finite element electromagnetic radiation and scattering problems is described. It is based on anechoic chamber absorber foam geometry, with specified complex permittivity and permeability. The advantage of this absorbing boundary is that it prevents reflections from much wider incident angles than currently used lattice termination conditions. Since

C. M. Rappaport; L. J. Bahrmasel

1992-01-01

203

Porous metal absorbers for underwater sound.  

PubMed

Rubber has traditionally been used for underwater sound absorption. Porous metal is a relatively lightweight material and also has higher strength than rubber. However, exactly how porous metals can be used as effective underwater sound absorbers remains unclear. This paper shows how to use porous metal absorbers so that they work well under water, even under fairly constrained conditions. A method of nondimensional analysis is proposed that allows identification of vital characteristics. This means that such characteristics can be varied and the absorbers themselves filled with different types of viscous fluids. Such analysis suggests that the sound absorption coefficient of porous metals does not always increase when there are either increases in porosity or decreases in average pore size. The same method of analysis can show how, by choice of the right characteristics to choose a suitable viscous fluid, a porous metal absorber can be built that takes up little space but still effectively absorbs underwater sounds at low frequencies. PMID:18189554

Wang, Xiaolin

2007-11-01

204

Solar sustained plasma/absorber conceptual design  

NASA Technical Reports Server (NTRS)

A space power system concept was evaluated which uses concentrated solar energy to heat a working fluid to temperatures as high as 4000 K. The high temperature working fluid could be used for efficient electric power production in advanced thermal or magnetohydrodynamic conversion cycles. Energy absorber configurations utilizing particles or cesium vapor absorber material were investigaed. Results of detailed radiant heat transfer calculations indicated approximately 86 percent of the incident solar energy could be absorbed within a 12-cm-dia flowing stream of gas borne carbon particles. Calculated total energy absorption in the cesium vapor seeded absorber configuration ranged from 34 percent to 64 percent of the incident solar energy. Solar flux concentration ratios of between approximately 3000 and 10,000 will be required to sustain absorber temperatures in the range from 3000 K to 4000 K.

Rodgers, R. J.; Krascella, N. L.; Kendall, J. S.

1979-01-01

205

Clumpy disc and bulge formation  

NASA Astrophysics Data System (ADS)

We present a set of hydrodynamical/N-body controlled simulations of isolated gas-rich galaxies that self-consistently include supernova (SN) feedback and a detailed chemical evolution model, both tested in cosmological simulations. The initial conditions are motivated by the observed star-forming galaxies at z ˜ 2-3. We find that the presence of a multiphase interstellar media in our models promotes the growth of disc instability favouring the formation of clumps which, in general, are not easily disrupted on time-scales compared to the migration time. We show that stellar clumps migrate towards the central region and contribute to form a classical-like bulge with a Sérsic index, n > 2. Our physically motivated SN feedback has a mild influence on clump survival and evolution, partially limiting the mass growth of clumps as the energy released per SN event is increased, with the consequent flattening of the bulge profile. This regulation does not prevent the building of a classical-like bulge even for the most energetic feedback tested. Our SN feedback model is able to establish self-regulated star formation, producing mass-loaded outflows and stellar age spreads comparable to observations. We find that the bulge formation by clumps may coexist with other channels of bulge assembly such as bars and mergers. Our results suggest that galactic bulges could be interpreted as composite systems with structural components and stellar populations storing archaeological information of the dynamical history of their galaxy.

Perez, Josefa; Valenzuela, Octavio; Tissera, Patricia B.; Michel-Dansac, Leo

2013-11-01

206

Cold streams in early massive hot haloes as the main mode of galaxy formation.  

PubMed

Massive galaxies in the young Universe, ten billion years ago, formed stars at surprising intensities. Although this is commonly attributed to violent mergers, the properties of many of these galaxies are incompatible with such events, showing gas-rich, clumpy, extended rotating disks not dominated by spheroids. Cosmological simulations and clustering theory are used to explore how these galaxies acquired their gas. Here we report that they are 'stream-fed galaxies', formed from steady, narrow, cold gas streams that penetrate the shock-heated media of massive dark matter haloes. A comparison with the observed abundance of star-forming galaxies implies that most of the input gas must rapidly convert to stars. One-third of the stream mass is in gas clumps leading to mergers of mass ratio greater than 1:10, and the rest is in smoother flows. With a merger duty cycle of 0.1, three-quarters of the galaxies forming stars at a given rate are fed by smooth streams. The rarer, submillimetre galaxies that form stars even more intensely are largely merger-induced starbursts. Unlike destructive mergers, the streams are likely to keep the rotating disk configuration intact, although turbulent and broken into giant star-forming clumps that merge into a central spheroid. This stream-driven scenario for the formation of discs and spheroids is an alternative to the merger picture. PMID:19158792

Dekel, A; Birnboim, Y; Engel, G; Freundlich, J; Goerdt, T; Mumcuoglu, M; Neistein, E; Pichon, C; Teyssier, R; Zinger, E

2009-01-22

207

Radar cross section reduction by absorber covering  

NASA Technical Reports Server (NTRS)

Radar cross section (RCS) reduction by absorber covering is experimentally studied by employing microwave diversity imaging. Experimental results show that broadband absorber covering is not effective at reducing the co-polarized (the transmitting and receiving antennas have opposite sense of circular polarization) RCS of a plate when the incident wave approximates the edge-on direction but is effective at reducing the cross-polarized (both the transmitting and receiving antennas have the same sense of circular polarization) RCS for all incident directions. The surface current absorber covering is effective at reducing the nonspecular energy and multiple bounces regardless of the polarization status of the measurement.

Li, H. J.; Farhat, N. H.; Shen, Y.

1989-01-01

208

Cold quark matter  

NASA Astrophysics Data System (ADS)

We perform an O(?s2) perturbative calculation of the equation of state of cold but dense QCD matter with two massless and one massive quark flavor, finding that perturbation theory converges reasonably well for quark chemical potentials above 1 GeV. Using a running coupling constant and strange quark mass, and allowing for further nonperturbative effects, our results point to a narrow range where absolutely stable strange quark matter may exist. Absent stable strange quark matter, our findings suggest that quark matter in (slowly rotating) compact star cores becomes confined to hadrons only slightly above the density of atomic nuclei. Finally, we show that equations of state including quark matter lead to hybrid star masses up to M˜2M?, in agreement with current observations. For strange stars, we find maximal masses of M˜2.75M? and conclude that confirmed observations of compact stars with M>2M? would strongly favor the existence of stable strange quark matter.

Kurkela, Aleksi; Romatschke, Paul; Vuorinen, Aleksi

2010-05-01

209

Cold isopressing method  

DOEpatents

A cold isopressing method in which two or more layers of material are formed within an isopressing mold. One of the layers consists of a tape-cast film. The layers are isopressed within the isopressing mold, thereby to laminate the layers and to compact the tape-cast film. The isopressing mold can be of cylindrical configuration with the layers being coaxial cylindrical layers. The materials used in forming the layers can contain green ceramic materials and the resultant structure can be fired and sintered as necessary and in accordance with known methods to produce a finished composite, ceramic structure. Further, such green ceramic materials can be of the type that are capable of conducting hydrogen or oxygen ions at high temperature with the object of utilizing the finished composite ceramic structure as a ceramic membrane element.

Chen, Jack C. (Getzville, NY); Stawisuck, Valerie M. (North Tonawanda, NY); Prasad, Ravi (East Amherst, NY)

2003-01-01

210

Hot Planet - Cold Comfort  

NSDL National Science Digital Library

This page features videos from the "Hot Planet- Cold Comfort" television episode, related website articles and a student activity. The videos explore how the Gulf Stream conveyor belt may shut down; how Arctic river runoff and Alaskan glacial melt are freshening the oceans; and how ocean sediments and ice cores are being studied to understand the Little Ice Age. The videos total approximately one hour in length. The website articles explore the Little Ice Age; how the Arctic functions as a global thermostat, affecting global weather patterns; and great moments in climate change. The student activity is about light absorbtion. The site also contains a challenge activity to find details in a painting that depict Little Ice Age living conditions.

211

Freezing cold injury.  

PubMed

The pathogenesis of freezing cold injuries (FCI) is not yet entirely understood. Two possible hypothesis emerge: 1) Injury is a direct result of cryogenic insult to the cells. 2) Injury is secondary to vascular stasis which leads to anoxia. In clinical congelatio ice crystallization takes place in the EC-space. When water is transformed into ice, the osmolality in this compartment will increase leading to a passive diffusion of water from the IC-space. Cell dehydration modifies protein structure, alters membrane lipids and cellular pH leading to destructions incompatible with cell survival. Cold induces vasoconstriction of both arterioles and venules, which enhances peripheral filtration and raises plasma viscosity. The stability of red corpuscle aggregates increases and showers of emboli course microvessels. Finally progressive thrombosis will end up in anoxia. The indirect vascular effect has earlier been interpreted similar to that found in non-freezing injuries. Recent studies have, however, shown, that endothelial cells are very sensitive to freezing. The rheologic part of the pathogenesis therefore also seems to depend on a direct injury to cells. The development of FCI does not always depend on ambient temperature and duration of exposure but more to the heat loss subjected to exposed skin. Wind chill, humidity and wetness are all of significance in this matter. From a clinical point of view FCI are best subdivided into superficial and deep injuries. The superficial frostbite is limited to the skin and nearest subcutaneous tissue. A stringing, pinching pain is often the first symptom. The affected area becomes pale or waxy-white and numb.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1811585

Granberg, P O

1991-01-01

212

WARM GAS IN THE VIRGO CLUSTER. I. DISTRIBUTION OF Ly{alpha} ABSORBERS  

SciTech Connect

The first systematic study of the warm gas (T = 10{sup 4-5} K) distribution across a galaxy cluster is presented using multiple background QSOs in and around the Virgo Cluster. We detect 25 Ly{alpha} absorbers (N{sub HI} = 10{sup 13.1-15.4} cm{sup -2}) in the Virgo velocity range toward 9 of 12 QSO sightlines observed with the Cosmic Origin Spectrograph, with a cluster impact parameter range of 0.36-1.65 Mpc (0.23-1.05 R{sub vir}). Including 18 Ly{alpha} absorbers previously detected by STIS or GHRS toward 7 of 11 background QSOs in and around the Virgo Cluster, we establish a sample of 43 absorbers toward a total of 23 background probes for studying the incidence of Ly{alpha} absorbers in and around the Virgo Cluster. With these absorbers, we find (1) warm gas is predominantly in the outskirts of the cluster and avoids the X-ray-detected hot intracluster medium (ICM). Also, Ly{alpha} absorption strength increases with cluster impact parameter. (2) Ly{alpha}-absorbing warm gas traces cold H I-emitting gas in the substructures of the Virgo Cluster. (3) Including the absorbers associated with the surrounding substructures, the warm gas covering fraction (100% for N{sub HI} > 10{sup 13.1} cm{sup -2}) is in agreement with cosmological simulations. We speculate that the observed warm gas is part of large-scale gas flows feeding the cluster both in the ICM and galaxies.

Yoon, Joo Heon; Putman, Mary E.; Bryan, Greg L. [Department of Astronomy, Columbia University, New York, NY 10027 (United States); Thom, Christopher [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21211 (United States); Chen, Hsiao-Wen, E-mail: jhyoon@astro.columbia.edu [Department of Astronomy and Astrophysics and Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States)

2012-08-01

213

Aquaculture using cold OTEC water  

Microsoft Academic Search

The unique 2000 ft deep seawater pipeline installed at the Natural Energy Laboratory of Hawaii (NELH) supplies the only cold seawater available in large volumes anywhere in the tropics. Not only does the low temperature of the cold seawater required for the OTEC process permit the tropical culture of species normally found only in colder areas, it also allows inexpensive

Thomas H. Daniel

1985-01-01

214

Encyclopedia of the Cold War  

Microsoft Academic Search

Between 1945 and 1991, tension between the USA, its allies, and a group of nations led by the USSR, dominated world politics. This period was called the Cold War – a conflict that stopped short to a full-blown war. Benefiting from the recent research of newly open archives, the Encyclopedia of the Cold War discusses how this state of perpetual

Dijk van R

2008-01-01

215

Thermoregulatory modeling for cold stress.  

PubMed

Modeling for cold stress has generated a rich history of innovation, has exerted a catalytic influence on cold physiology research, and continues to impact human activity in cold environments. This overview begins with a brief summation of cold thermoregulatory model development followed by key principles that will continue to guide current and future model development. Different representations of the human body are discussed relative to the level of detail and prediction accuracy required. In addition to predictions of shivering and vasomotor responses to cold exposure, algorithms are presented for thermoregulatory mechanisms. Various avenues of heat exchange between the human body and a cold environment are reviewed. Applications of cold thermoregulatory modeling range from investigative interpretation of physiological observations to forecasting skin freezing times and hypothermia survival times. While these advances have been remarkable, the future of cold stress modeling is still faced with significant challenges that are summarized at the end of this overview. Published 2014. Compr Physiol 4:1057-1081, 2014. PMID:24944030

Xu, Xiaojiang; Tikuisis, Peter

2014-07-01

216

Hypothermia and localized cold injuries  

Microsoft Academic Search

Accidental hypothermia and localized cold injuries remain a significant public health problem. The deleterious effect of cold exposure on human performance and health has been documented for centuries. Some of the earliest descriptions came from Baron de Larrey, Napoleon's chief surgeon. During the disastrous invasion of Russia in 1812 he depicted the mental and physical hardships endured by the French

Andrew S. Ulrich; Niels K. Rathlev

2004-01-01

217

The status of cold fusion  

NASA Astrophysics Data System (ADS)

This report attempts to update the status of the phenomenon of cold fusion. The new field is continuing to grow as a variety of nuclear reactions are discovered to occur in a variety of chemical environments at modest temperatures. However, it must be cautioned that most scientists consider cold fusion as something akin to UFO's, ESP, and numerology.

Storms, E.

218

Cold Urticaria and Celiac Disease  

Microsoft Academic Search

? Abstract Cold urticaria can be associated with blood and thyroid disorders, drugs, or infections. Celiac disease is an autoimmune enteropathy caused by permanent gluten intolerance. It is often associated with other autoimmune diseases, such as chronic idiopathic urticaria. Nevertheless, association with cold urticaria has not yet been described. A boy aged 3 years 8 months presented local urticaria-angioedema when

M Pedrosa Delgado; F Martín Muñoz; I Polanco Allué; M Martín Esteban

219

Tunable bandwidth of the terahertz metamaterial absorber  

NASA Astrophysics Data System (ADS)

We propose a broadband terahertz metamaterial absorber that utilizes the coupling effect of the sub-unit elements of the structure consisted of two asymmetric metallic square rings and a metallic ground plane separated by a dielectric layer. The bandwidth of the absorber is tunable over a range from 0.88 to 1.28 THz by the coupling distance of the two patterned square rings. The proposed absorber has the tunability from broadband to single-band by the polarization angle of the system. Moreover, the proposed concept also applies to other types of asymmetric absorber structure and can be readily extended to other frequency regimes for a host of applications such as detection, imaging and solar cell.

Wang, Ben-Xin; Wang, Ling-Ling; Wang, Gui-Zhen; Huang, Wei-Qing; Zhai, Xiang; Li, Xiao-Fei

2014-08-01

220

Passive Earth Entry Vehicle Energy Absorbing Systems  

NASA Astrophysics Data System (ADS)

A critical element of a passive EEV performance is the energy absorbing system required to attenuate the dynamic landing loads. Two design approaches are described and the pros and cons based on particular mission requirements are discussed.

Kellas, S.; Maddock, R. W.

2014-06-01

221

Neutron absorbing coating for nuclear criticality control  

DOEpatents

A neutron absorbing coating for use on a substrate, and which provides nuclear criticality control is described and which includes a nickel, chromium, molybdenum, and gadolinium alloy having less than about 5% boron, by weight.

Mizia, Ronald E. (Idaho Falls, ID); Wright, Richard N. (Idaho Falls, ID); Swank, William D. (Idaho Falls, ID); Lister, Tedd E. (Idaho Falls, ID); Pinhero, Patrick J. (Idaho Falls, ID)

2007-10-23

222

Non-absorbed Antibiotics for IBS.  

National Technical Information Service (NTIS)

A recent manuscript described two multi-center, prospective double blind trials of the non-absorbed antibiotic rifaximin for nonconstipated irritable bowel syndrome (IBS). This effort adds to the body of literature from other, smaller studies that have de...

B. D. Cash

2012-01-01

223

Optimum Design of Wide Frequency Vibration Absorbers.  

National Technical Information Service (NTIS)

A nondimensional vibration parameters expression is presented which is suitable for design of vibration absorbers. Compared with the single-degree-of-freedom system, the results show that the numerical analyses in parameter design are made to wide frequen...

X. Song Z. Zhou J. Wu

1993-01-01

224

Radar Absorbing Materials: Mechanisms and Materials.  

National Technical Information Service (NTIS)

An introduction is given to the theoretical basis for the design of radar absorbing materials (RAM) with emphasis given on techniques for modifying material properties to give the desired performance. These techniques include additives in the form of scat...

K. Gaylor

1989-01-01

225

Determination of absorbed beta dose in materials  

SciTech Connect

It is necessary during construction and subsequent operation of a commercial nuclear power reactor to evaluate the impact of the absorbed dose on the useful life of equipment and components. Routinely, the gamma contribution to this absorbed dose is evaluated, and major vendors provide information pertaining to equipment qualification for use in a radiation environment. When evaluating the absorbed beta dose to facility equipment, the source term is readily available during construction from the vendor's radiation design guide. This source term may be used to project potential post-loss of coolant accident (LOCA) equipment dose. After rector startup, the actual source term may be determined by laboratory analysis of the affected system components. This article clarifies existing practices and calculational methods, and provides a straight-forward method for evaluating the absorbed beta dose in materials.

Brown, D.D. (Chem-Nuclear Geotech, Inc. (US))

1992-07-01

226

Attenuation of external Bremsstrahlung in metallic absorbers  

SciTech Connect

In this paper attenuation of bremsstrahlung from {sup 147}Pm and {sup 170}Tm beta emitters has been studied in aluminum, copper, tin, and lead metallic absorbers. Bremsstrahlung spectra and mass attenuation coefficients for monoenergetic gamma rays are used to calculate theoretical attenuation curves. Magnetic deflection and beta stopping techniques are used to measure the integral bremsstrahlung intensities above 30 keV in different target thicknesses. Comparison of measured and calculated attenuation curves shows a good agreement for various absorbers, thus providing a test of this technique, which may be useful in understanding bremsstrahlung intensity buildup and in the design of optimum shielding for bremsstrahlung sources. It is found that the absorption of bremsstrahlung in metallic absorbers does not obey an exponential law and that absorbers act as energy filters.

Dhaliwal, A.S.; Powar, M.S.; Singh, M. (Punjabi Univ., Physics Dept., Patiala 147002 (IN))

1990-12-01

227

Pneumatic Spring with Hydraulic Shock Absorber.  

National Technical Information Service (NTIS)

This patent describes a pneumatic spring with a hydraulic shock absorber, principally for heavy automobiles. This device is distinguished by the fact that, in order to regulate the oscillation frequency, it is provided with an annular counterpressure cham...

Z. L. Sirotkin L. I. Dobrykh A. A. Khodasevich

1969-01-01

228

Multifunctional Space Evaporator-Absorber-Radiator (SEAR).  

National Technical Information Service (NTIS)

A system for non-venting thermal control for spacesuits was built by integrating two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's flexible version of the Lithium Chloride Absorber Radiator (LCAR...

E. Hodgson, G. C. Bue, M. Izenson, W. Chen

2013-01-01

229

An ultra-broadband multilayered graphene absorber.  

PubMed

An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon modes that destructively interfere with the dipolar mode and generate electromagnetically induced absorption. (ii) The patterned graphene layers biased at different gate voltages backed-up with dielectric substrates are stacked on top of each other. The resulting absorber is polarization dependent but has an ultra-broadband of operation. (iii) Graphene's damping factor is increased by lowering its electron mobility to 1000 cm²/Vs. Indeed, numerical experiments demonstrate that with only three layers, bandwidth of 90% absorption can be extended upto 7THz, which is drastically larger than only few THz of bandwidth that can be achieved with existing metallic/graphene absorbers. PMID:24514545

Amin, Muhammad; Farhat, Mohamed; Ba?c?, Hakan

2013-12-01

230

Guided-mode resonant coherent light absorbers.  

PubMed

We present a new class of coherent perfect absorbers based on guided-mode resonance in thin semiconductor films. Using particle-swarm optimization methods, we design a thin-film amorphous silicon grating that maximizes coherent modulation of the absorbance. The optimized device exhibits a maximum scattering power of ?94% and a power absorption limit approaching 100% at the 1550-nm wavelength. PMID:24487846

Giese, J A; Yoon, J W; Wenner, B R; Allen, J W; Allen, M S; Magnusson, R

2014-02-01

231

Terahertz backscattering behavior of various absorbing materials  

NASA Astrophysics Data System (ADS)

The Submillimeter-Wave Technology Laboratory (STL) at the University of Massachusetts Lowell has investigated the electromagnetic scattering behavior of various broadband absorbers. Several absorbing materials were tested in a compact radar range operating at a center frequency of 160 GHz. The polarimetric radar cross section was measured at elevation angles from 15° to 75°. In addition to the backscattering behavior, the normal incidence transmittance of the materials was evaluated.

Wu, C.; Gatesman, A. J.; Deroeck, L.; Horgan, T.; Giles, R. H.; Nixon, W. E.

2009-05-01

232

Radar Cross Section Reduction by Absorber Covering  

Microsoft Academic Search

Radar cross section (RCS) reduction by absorber covering is experimentally studied by employing microwave diversity imaging. Experimental results show that broadband absorber covering is not effective at reducing the co-polarized (the transmitting andreceiving antennas have opposite sense of circular polarization) RCS of a plate when the incident wave approximates the edge-on direction but is effective at reducing the cross-polarized (both

H. J. Li; N. H. Farhat; Y. Shen

1989-01-01

233

Radar cross section reduction by absorber covering  

Microsoft Academic Search

Radar cross section (RCS) reduction by absorber covering is experimentally studied by employing microwave diversity imaging. Experimental results show that broadband absorber covering is not effective at reducing the co-polarized (the transmitting and receiving antennas have opposite sense of circular polarization) RCS of a plate when the incident wave approximates the edge-on direction but is effective at reducing the cross-polarized

H. J. Li; N. H. Farhat; Y. Shen

1989-01-01

234

21 CFR 880.5300 - Medical absorbent fiber.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Medical absorbent fiber. 880.5300 Section 880.5300 Food...Devices § 880.5300 Medical absorbent fiber. (a) Identification. A medical absorbent fiber is a device intended for medical...

2013-04-01

235

Modal properties and stability of centrifugal pendulum vibration absorber systems with equally spaced, identical absorbers  

NASA Astrophysics Data System (ADS)

This work develops an analytical model of centrifugal pendulum vibration absorber systems with equally spaced, identical absorbers and uses it to investigate the structure of the modal vibration properties. The planar model admits two translational and one rotational degrees-of-freedom for the rotor and a single arclength degree-of-freedom for each absorber. The gyroscopic effects from rotor rotation are taken into account. Examination of the associated eigenvalue problem reveals well-defined structure of the vibration modes resulting from the cyclic symmetry of the absorbers. The vibration modes are classified into rotational, translational, and absorber modes. Characteristics of each mode type are analytically proved. The effects of the absorber tuning order on the modes are derived. The critical speeds and flutter instability of the system are studied numerically and analytically.

Shi, Chengzhi; Parker, Robert G.

2012-10-01

236

Cold plasma decontamination of foods.  

PubMed

Cold plasma is a novel nonthermal food processing technology that uses energetic, reactive gases to inactivate contaminating microbes on meats, poultry, fruits, and vegetables. This flexible sanitizing method uses electricity and a carrier gas, such as air, oxygen, nitrogen, or helium; antimicrobial chemical agents are not required. The primary modes of action are due to UV light and reactive chemical products of the cold plasma ionization process. A wide array of cold plasma systems that operate at atmospheric pressures or in low pressure treatment chambers are under development. Reductions of greater than 5 logs can be obtained for pathogens such as Salmonella, Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus. Effective treatment times can range from 120 s to as little as 3 s, depending on the food treated and the processing conditions. Key limitations for cold plasma are the relatively early state of technology development, the variety and complexity of the necessary equipment, and the largely unexplored impacts of cold plasma treatment on the sensory and nutritional qualities of treated foods. Also, the antimicrobial modes of action for various cold plasma systems vary depending on the type of cold plasma generated. Optimization and scale up to commercial treatment levels require a more complete understanding of these chemical processes. Nevertheless, this area of technology shows promise and is the subject of active research to enhance efficacy. PMID:22149075

Niemira, Brendan A

2012-01-01

237

Cold urticaria and celiac disease.  

PubMed

Cold urticaria can be associated with blood and thyroid disorders, drugs, or infections. Celiac disease is an autoimmune enteropathy caused by permanent gluten intolerance. It is often associated with other autoimmune diseases, such as chronic idiopathic urticaria. Nevertheless, association with cold urticaria has not yet been described. A boy aged 3 years 8 months presented local urticaria-angioedema when exposed to cold temperatures. An ice cube test was positive and iron deficiency anemia was demonstrated. He later developed legume intolerance, rhinoconjunctivitis related to pollen sensitization, and asthma. Due to persistence of cold urticaria symptoms and refractory anemia, a test for immunoglobulin A autoantibodies to tissue transglutaminase and an intestinal biopsy were performed. Results of both tests were compatible with celiac disease.A study of human leukocyte antigen indicated a high risk phenotype (HLA, DR6/DR7; DQA 0501, 0201; DQB 0301, 0201). After 7 months of a gluten-free diet, the boy's anemia resolved and he is free of symptoms when exposed to cold. This is a first description of the possibility of an association between celiac disease and cold urticaria. A poor course of cold urticaria in the absence of evidence of another underlying condition should lead to suspicion of celiac disease. PMID:18447142

Pedrosa Delgado, M; Martín Muñoz, F; Polanco Allué, I; Martín Esteban, M

2008-01-01

238

Cold fusion verification  

NASA Astrophysics Data System (ADS)

The objective of this work to verify and reproduce experimental observations of Cold Nuclear Fusion (CNF), as originally reported in 1989. The method was to start with the original report and add such additional information as became available to build a set of operational electrolytic CNF cells. Verification was to be achieved by first observing cells for neutron production, and for those cells that demonstrated a nuclear effect, careful calorimetric measurements were planned. The authors concluded, after laboratory experience, reading published work, talking with others in the field, and attending conferences, that CNF probably is chimera and will go the way of N-rays and polywater. The neutron detector used for these tests was a completely packaged unit built into a metal suitcase that afforded electrostatic shielding for the detectors and self-contained electronics. It was battery-powered, although it was on charge for most of the long tests. The sensor element consists of He detectors arranged in three independent layers in a solid moderating block. The count from each of the three layers as well as the sum of all the detectors were brought out and recorded separately. The neutron measurements were made with both the neutron detector and the sample tested in a cave made of thick moderating material that surrounded the two units on the sides and bottom.

North, M. H.; Mastny, G. F.; Wesley, E. J.

1991-03-01

239

Method of warming cold engines in cold climates  

SciTech Connect

This patent describes a method of warming cold engines in low temperature conditions comprising the steps of: (a) placing a flammable compound inside a nonflammable fabric bag; (b) placing the bag on an engine; and (c) igniting the flammable compound.

Forschirm, A.

1988-12-06

240

Gas absorber and refrigeration system using same  

SciTech Connect

A refrigeration system is described comprising: (a) a separator for separating a refrigerant gas from a refrigerant-rich solution to produce a refrigerant-lean solution; (b) a condenser for emitting heat to thereby condense the refrigerant gas received from the separator and an evaporator for absorbing heat to thereby evaporate the condensed refrigerant gas; (c) an absorber assembly including: a precooler for precooling the refrigerant-lean solution received from the separator; a mixer for mixing the refrigerant gas from the evaporator with the precooled refrigerant-lean solution received form the precooler to thereby form a gas-solution mixture, the mixer having nozzles for allowing the refrigerant-lean solution to be injected there through into a flow of the gas-solution mixture, the nozzles being adapted to cause the refrigerant-lean solution to experience a predetermined pressure drop there across; and absorbent tubes for allowing the gas-solution mixture to flow there through while causing the refrigerant-lean solution to absorb the refrigerant gas to thereby generate a refrigerant-rich solution; (d) a solution receiver for receiving the refrigerant-rich solution through the absorber tubes and a manifold for containing an overflow through the absorber tubes during a normal operation of the refrigeration system, an upper part of the solution receiver serving to contain the refrigerant gas; (e) recycling means for controllably recycling the refrigerant gas from the solution receiver into the absorber assembly; and a solution pump for delivering the refrigerant-rich solution from the solution receiver to the separator through a generator for heating the refrigerant-rich solution.

Dehne, H.

1993-08-24

241

Plants in a cold climate.  

PubMed Central

Plants are able to survive prolonged exposure to sub-zero temperatures; this ability is enhanced by pre-exposure to low, but above-zero temperatures. This process, known as cold acclimation, is briefly reviewed from the perception of cold, through transduction of the low-temperature signal to functional analysis of cold-induced gene products. The stresses that freezing of apoplastic water imposes on plant cells is considered and what is understood about the mechanisms that plants use to combat those stresses discussed, with particular emphasis on the role of the extracellular matrix.

Smallwood, Maggie; Bowles, Dianna J

2002-01-01

242

Ultraviolet radiation absorbing compounds in marine organisms  

SciTech Connect

Studies on the biological effects of solar ultraviolet radiations are becoming increasingly common, in part due to recent interest in the Antarctic ozone hole and in the perceived potential for global climate change. Marine organisms possess many strategies for ameliorating the potentially damaging effects of UV-B (280-320 nm) and the shorter wavelengths of UV-A (320-400nm). One mechanism is the synthesis of bioaccumulation of ultraviolet radiation absorbing compounds. Several investigators have noted the presence of absorbing compounds in spectrophotometer scans of extracts from a variety of marine organisms, particularly algae and coelenterates containing endosymbiotic algae. The absorbing compounds are often mycosporine-like amino acids. Thirteen mycosporine-like amino acids have already been described, and several others have recently been detected. Although, the mycosporine-like amino acids are widely distributed. these compounds are by no means the only type of UV-B absorbing compounds which has been identified. Coumarins from green algae, quinones from sponges, and indoles from a variety of sources are laternative examples which are documented in the natural products literature. When the biological impact of solar ultraviolet radiation is assessed, adequate attention must be devoted to the process of photoadaptation, including the accumulation of ultraviolet radiation absorbing compounds.

Chalker, B.E.; Dunlap, W.C. (Australian Inst. of Marine Science, Queensland (Australia))

1990-01-09

243

ANL Advanced Photon Source crotch absorber design  

SciTech Connect

The ANL 7-GeV Advanced Photon Source storage ring crotch absorber will be subjected to a very high photon loading power density, approximately 750 W/mm{sup 2} at normal incidence. To accommodate this high heat load, two designs were studied: one is a V-type compound angle absorber and the other is a horizontally rotated plate absorber. For both models, thermal and structural analyses have been carried out using 3-D finite element analysis. The analysis indicates that the V-type compound angle absorber controlled the peak temperatures effectively within the given geometric constraints. Test samples made of GlidCop Al 15 (alumina dispersion strengthened copper) were evaluated with an electron beam welder. The predicted and measured temperatures were in reasonable agreement. The overall absorber design includes a perforated screen in the positron beam area of the storage ring vacuum chamber to reduce rf impedance and to provide pumping access for the high local gas load. 3 refs., 4 figs., 2 tabs.

Choi, M. (Seoul National Univ. (Republic of Korea)); Gonczy, J.D.; Howell, J.W.; Niemann, R.C. (Argonne National Lab., IL (USA))

1991-01-01

244

Literature review: the common cold.  

PubMed

Most colds are caused by rhinovirus infection, perhaps facilitated by chilling or stress. Virus infection begins in the nasopharynx and causes spotty destruction of the nasal ciliated epithelium. Transmission occurs chiefly via droplets of various sizes transported through the air, but some types of virus persist in moist secretions on handled objects and may retain their infectiousness. Living in crowded, poorly-ventilated quarters facilitates transmission. Not many virus particles survive in saliva and it is difficult to infect via the lips or mouth. Kissing does not efficiently spread cold infection. Prophylactic treatment with interferon does not protect against cold infection. Aspirin and acetaminophen reduced serum antibody response and increased nasal symptoms in a controlled Australian study. The combination of intranasal interferon and ipratropium with oral naproxen gave promising results in experimental rhinovirus inoculation. Basically, there has been little or no progress towards effective cold treatment in the past century. PMID:7988393

Hilding, D A

1994-09-01

245

Stay Safe in Cold Weather!  

MedlinePLUS

... Aging Stay Safe in Cold Weather! What is hypothermia? If you are like most people, you feel ... knows what’s happening. Doctors call this serious problem hypothermia (hi-po- ther -mee-uh). Hypothermia is what ...

246

Cold regions hydrology and hydraulics  

SciTech Connect

This monograph addresses a narrow aspect of cold regions engineering, namely the effects of cold weather on the traditional civil engineering disciplines of hydrology and hydraulics. Hydrologic and hydraulic considerations in the design, construction, and operation of civil works are very important. Many of the problems encountered in the design and construction of buildings, transportation systems, water supply facilities, waste treatment facilities, and hazardous waste disposal facilities, for example are closely tied to the characteristics of the site hydrology.

Ryan, W.L. (HDR Engineers, Inc., Anchorage, AK (US)); Crissman, R.D. (NY Power Authority, Niagra Falls, NY (US))

1990-01-01

247

A perfectly matched anisotropic absorber for use as an absorbing boundary condition  

Microsoft Academic Search

An alternative formulation of the “perfectly matched layer” mesh truncation scheme is introduced. The present scheme is based on using a layer of diagonally anisotropic material to absorb outgoing waves from the computation domain. The material properties can be chosen such that the interface between the absorbing material and free space is reflection-less for all frequencies, polarizations, and angles of

Zachary S. Sacks; David M. Kingsland; Robert Lee; Jin-Fa Lee

1995-01-01

248

Spatial-frequency multiplication via absorbance modulation  

SciTech Connect

The absorbance of a thin film of photochromic material can be reversibly modified by exposure to two different wavelengths, {lambda}{sub 1} and {lambda}{sub 2}. When such a film is illuminated by both wavelengths simultaneously, and the longer wavelength {lambda}{sub 2} possesses a node in its intensity distribution, then the absorbance of the layer can be made high except at an arbitrarily small region near the node. By exploiting the large nonlinearity introduced by this mechanism, combined with the reversibility of the absorbance of the photochromic layer, the authors demonstrate that spatial frequencies larger than those present in incident intensity distributions may be generated. They show photoresist exposures to demonstrate this technique.

Tsai, H.-Y.; Wallraff, Gregory M.; Menon, Rajesh [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); IBM Almaden Research Center, San Jose, California 95120 (United States); Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and LumArray, Inc., Somerville, Massachusetts 02143 (United States)

2007-08-27

249

Optical analysis of solar energy tubular absorbers.  

PubMed

The energy absorbed by a solar energy tubular receiver element for a single incident ray is derived. Two types of receiver elements were analyzed: (1) an inner tube with an absorbing coating surrounded by a semitransparent cover tube, and (2) a semitransparent inner tube filled with an absorbing fluid surrounded by a semitransparent cover tube. The formation of ray cascades in the semitransparent tubes is considered. A numerical simulation to investigate the influence of the angle of incidence, sizing, thickness, and coefficient of extinction of the tubes was performed. A comparison was made between receiver elements with and without cover tubes. Ray tracing analyses in which rays were followed within the tubular receiver element as well as throughout the rest of the collector were performed for parabolic and circular trough concentrating collectors. PMID:20401004

Saltiel, C; Sokolov, M

1982-11-15

250

Wavelength-selective infrared Salisbury screen absorber.  

PubMed

Experimental long wavelength infrared spectral response characterization of a narrowband Salisbury screen absorber suitable for use in microbolometer focal plane arrays is presented. We have demonstrated a microfabricated germanium dielectric support structure layer that replaces the usual silicon nitride structural layer in microbolometers. The fabricated Salisbury screen absorber consists of a chromium resistive sheet as an absorber layer above a germanium dielectric/air-gap/interference structure. In order to produce wavelength-selective narrowband absorption, the general design rules for the germanium dielectric supported Salisbury screen show that the thickness of the air gap should be a half wavelength thick and the optical thickness of the germanium layer a quarter dielectric wavelength thick. PMID:24787414

Jung, Joo-Yun; Park, Jong Yeon; Han, Sangwook; Weling, Aniruddha S; Neikirk, Dean P

2014-04-10

251

Absorber Materials at Room and Cryogenic Temperatures  

SciTech Connect

We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun

2011-09-01

252

Translatory shock absorber for attitude sensors  

NASA Technical Reports Server (NTRS)

A translatory shock absorber is provided for mounting an attitude sensor thereon for isolating a sensor from translatory vibrations. The translatory shock absorber includes a hollow block structure formed as one piece to form a parallelogram. The absorber block structure includes a movable top plate for supporting the attitude sensor and a fixed base plate with opposed side plates interposed between. At the junctions of the side plates, and the base and top plates, there are provided grooves which act as flexible hinges for attenuating translatory vibrations. A damping material is supported on a pedestal which is carried on the base plate between the side plates thereof. The top of the damping material rests against the bottom surface of the top plate for eliminating the resonant peaks of vibration.

Vonpragenau, G. L.; Morgan, I. T., Jr.; Kirby, C. A. (inventors)

1976-01-01

253

Warm absorbers in X-rays (WAX), a comprehensive high-resolution grating spectral study of a sample of Seyfert galaxies - I. A global view and frequency of occurrence of warm absorbers.  

NASA Astrophysics Data System (ADS)

We present results from a homogeneous analysis of the broad-band 0.3-10 keV CCD resolution as well as of the soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. Our goal is to characterize warm absorbers (WAs) along the line of sight to the active nucleus. We significantly detect WAs in 65 per cent of the sample sources. Our results are consistent with WAs being present in at least half of the Seyfert galaxies in the nearby Universe, in agreement with previous estimates. We find a gap in the distribution of the ionization parameter in the range 0.5 < log ? < 1.5 which we interpret as a thermally unstable region for WA clouds. This may indicate that the WA flow is probably constituted by a clumpy distribution of discrete clouds rather than a continuous medium. The distribution of the WA column densities for the sources with broad Fe K? lines are similar to those sources which do not have broadened emission lines. Therefore, the detected broad Fe K? emission lines are bona fide and not artefacts of ionized absorption in the soft X-rays. The WA parameters show no correlation among themselves, with the exception of the ionization parameter versus column density. The shallow slope of the log ? versus log vout linear regression (0.12 ± 0.03) is inconsistent with the scaling laws predicted by radiation or magnetohydrodynamic-driven winds. Our results also suggest that WA and ultra fast outflows do not represent extreme manifestation of the same astrophysical system.

Laha, Sibasish; Guainazzi, Matteo; Dewangan, Gulab C.; Chakravorty, Susmita; Kembhavi, Ajit K.

2014-07-01

254

Precise dispersion equations of absorbing filter glasses  

NASA Astrophysics Data System (ADS)

The refractive indices versus wavelength of optical transparent glasses are measured at a few wavelengths only. In order to calculate the refractive index at any wavelength, a so-called Sellmeier series is used as an approximation of the wavelength dependent refractive index. Such a Sellmeier representation assumes an absorbing free (= loss less) material. In optical transparent glasses this assumption is valid since the absorption of such transparent glasses is very low. However, optical filter glasses have often a rather high absorbance in certain regions of the spectrum. The exact description of the wavelength dependent function of the refractive index is essential for an optimized design for sophisticated optical applications. Digital cameras use an IR cut filter to ensure good color rendition and image quality. In order to reduce ghost images by reflections and to be nearly angle independent absorbing filter glass is used, e.g. blue glass BG60 from SCHOTT. Nowadays digital cameras improve their performance and so the IR cut filter needs to be improved and thus the accurate knowledge of the refractive index (dispersion) of the used glasses must be known. But absorbing filter glass is not loss less as needed for a Sellmeier representation. In addition it is very difficult to measure it in the absorption region of the filter glass. We have focused a lot of effort on measuring the refractive index at specific wavelength for absorbing filter glass - even in the absorption region. It will be described how to do such a measurement. In addition we estimate the use of a Sellmeier representation for filter glasses. It turns out that in most cases a Sellmeier representation can be used even for absorbing filter glasses. Finally Sellmeier coefficients for the approximation of the refractive index will be given for different filter glasses.

Reichel, S.; Biertümpfel, Ralf

2014-05-01

255

Optimization and engineering of microwave absorbers  

NASA Astrophysics Data System (ADS)

In this thesis, a concerted effort has been made to study and evaluate the individual electromagnetic properties of the absorbing components including carbon black, conducting fibers, metal flakes, magnetic materials such as carbonyl iron, ferrite and the chiral type of micro- carbon coil. The study of the electromagnetic properties covers functions such as dielectric dissipation, random scattering effect at low and high frequencies, magnetic dissipation at high frequencies and also the effect of chirality for different angles of incidence. The results of these studies have been used in the design, engineering and optimization of the microwave absorbers. The objective of this thesis is to identify the absorption mechanism of each of various type of fillers and to study the synergic effect arising from a combination of these in a non-metallic host medium. This will help us in producing microwave absorbers suitable for broad band application with the advantages of light weight, having high strength and possessing good chemical resistance. The results from experimental measurements of various material combinations have been greatly influenced by the theoretical understanding of the absorption mechanism. Design of microwave absorbers is governed by the requirement of the users as well as the characteristics of the objects (targets) inferred by theoretical understanding and experimental data to arrive at the right formula. Finally a detailed quality control program has to be charted out reflecting both the electromagnetic as well as mechanical properties. This is done by carrying out the tests systematically on small samples and then proceeding to practical absorbers making use of the data compiled earlier on smaller samples. In this thesis, to modify all dielectric absorbing components including micro-carbon chirals to reduce the sensitivity of absorption for different incident angles is unprecedented topic.

Chen, Kuo-Liang

1998-12-01

256

Polarization insensitive, broadband terahertz metamaterial absorber.  

PubMed

We present the simulation, implementation, and measurement of a polarization insensitive broadband resonant terahertz metamaterial absorber. By stacking metal-insulator layers with differing structural dimensions, three closely positioned resonant peaks are merged into one broadband absorption spectrum. Greater than 60% absorption is obtained across a frequency range of 1.86?THz where the central resonance frequency is 5?THz. The FWHM of the device is 48%, which is two and half times greater than the FWHM of a single layer structure. Such metamaterials are promising candidates as absorbing elements for bolometric terahertz imaging. PMID:21886249

Grant, James; Ma, Yong; Saha, Shimul; Khalid, Ata; Cumming, David R S

2011-09-01

257

SELECTIVE ABSORBER COATED FOILS FOR SOLAR COLLECTORS  

SciTech Connect

Solar absorber metal foils are discussed in terms of materials and basic processing science. Also included is the use of finished heavy sheet stock for direct fabrication of solar collector panels. Both the adhesives and bonding methods for foils and sheet are surveyed. Developmental and representative commercial foils are used as illustrative examples. As a result it was found that foils can compete economically with batch plating but are limited by adhesive temperature stability. Also absorber foils are very versatile and direct collector fabrication from heavy foils appears very promising.

Lampert, Carl M.

1980-04-01

258

Biomolecular Effects of Cold Plasma Exposure  

NASA Technical Reports Server (NTRS)

The effects of cold plasma exposure on Deinococcus radiodurans, plasmid DNA and model proteins were assessed using microbiological, spectrometric and biochemical techniques. Exposure of D. radiodurans, an extremely radiation resistant microbe, to O2 plasma (less than or equal to 25 W, approx. 45 mTorr, 90 min) yielded a approx. 99.999 % sterilization and the sterilization rate was increased approx. 10-fold at 100 W and 500 mTorr. AFM images shows that the exposed cells are significantly deformed and possess 50-70 nm concavities. IR analysis indicates the chemical degradation of lipids, proteins and carotenoids of the cell wall and membrane. Intracellular damage was indicated by major absorbance loss at 1245, 1651 and 1538/cm corresponding to degradation of DNA and proteins, respectively. Biochemical experiments demonstrate that plasmas induce strand scissions and crosslinking of plasmid DNA, and reduction of enzyme activity; the degradation is power dependent with total sample loss occurring in 60 s at 200 W and 500 mTorr. Emission spectroscopy shows that D. radiodurans is volatilized into CO2, CO, N2 and H2O confirming the removal of biological matter from contaminated surfaces. The O2 plasma impacts several cellular components predominantly through chemical degradation by atomic oxygen. A CO2, plasma, however, was not effective at degrading D. radiodurans, revealing the importance of plasma composition, which has implications for planetary protection and the contamination of Mars.

Mogul, Rakesh; Bolshakov, Alexander A.; Chan, Suzanne L.; Stevens, Ramsey D.; Khare, Bishun N.; Meyyappan, M.; Trent, Jonathan D.; DeVincenzi, D. (Technical Monitor)

2002-01-01

259

Observing Cold Dust with Herschel / SPIRE  

NASA Astrophysics Data System (ADS)

A major component of the emission of many galaxies is in the Far Infrared and the Sub-mmillimeter. UV photons from stars are absorbed by dust and re-emitted at longer wavelengths. Fairly cold dust was found in large spirals by the Infrared Space Observatory and the Spitzer Observatory, but their longest wavelength filters were centered at 200 and 160 microns respectively, restricting detection to dust warmer than about 15 Kelvin, and missing a major part of the dust mass. The Spectral and Photometric Imaging Receiver SPIRE ([1]) is one of the 3 instruments on board of the Herschel Space Observatory that was launched on 14 May 2009. The instrument hosts bolometer arrays with broadband photometric filters, centered at 250, 350 and 500 ?m, as well as an imaging Fourier Transform Spectrometer, covering the range from 200 to 670 ?m at 3 different spectral resolutions. This long wavelength coverage will, among many other subjects, allow for studies that take the entire dust content of a galaxy into account. The 3 instruments of Herschel are currently undergoing performance-and science-verification operations, followed by the execution of the first large key science programs. A call for smaller open time programs is expected to be issued after the science verification phase is complete.

Schulz, Bernhard

2010-06-01

260

EDITORIAL: Cold Quantum GasesEditorial: Cold Quantum Gases  

NASA Astrophysics Data System (ADS)

This Special Issue of Journal of Optics B: Quantum and Semiclassical Optics brings together the contributions of various researchers working on theoretical and experimental aspects of cold quantum gases. Different aspects of atom optics, matter wave interferometry, laser manipulation of atoms and molecules, and production of very cold and degenerate gases are presented. The variety of subjects demonstrates the steadily expanding role associated with this research area. The topics discussed in this issue, extending from basic physics to applications of atom optics and of cold atomic samples, include: bulletBose--Einstein condensation bulletFermi degenerate gases bulletCharacterization and manipulation of quantum gases bulletCoherent and nonlinear cold matter wave optics bulletNew schemes for laser cooling bulletCoherent cold molecular gases bulletUltra-precise atomic clocks bulletApplications of cold quantum gases to metrology and spectroscopy bulletApplications of cold quantum gases to quantum computing bulletNanoprobes and nanolithography. This special issue is published in connection with the 7th International Workshop on Atom Optics and Interferometry, held in Lunteren, The Netherlands, from 28 September to 2 October 2002. This was the last in a series of Workshops organized with the support of the European Community that have greatly contributed to progress in this area. The scientific part of the Workshop was managed by A Hemmerich, W Hogervorst, W Vassen and J T M Walraven, with input from members of the International Programme Committee who are listed below. The practical aspects of the organization were ably handled by Petra de Gijsel from the Vrije Universiteit in Amsterdam. The Workshop was funded by the European Science Foundation (programme BEC2000+), the European Networks 'Cold Quantum Gases (CQG)', coordinated by E Arimondo, and 'Cold Atoms and Ultraprecise Atomic Clocks (CAUAC)', coordinated by J Henningsen, by the German Physical Society (DFG), by the Dutch Foundation for Fundamental Research on Matter (FOM) and by the Dutch Gelderland province. We thank all these sponsors and the members of the International Programme Committee for making the Workshop such a success. At this point we take the opportunity to express our gratitude to both authors and reviewers, for their efforts in preparing and ensuring the high quality of the papers in this special issue. Wim Vassen Vrije Universiteit, Amsterdam Andreas Hemmerich Universität Hamburg Ennio Arimondo Università di Pisa Guest Editors International Programme Committee A Aspect Orsay, France E Cornell Boulder, USA W Ertmer Hannover, Germany T W Haensch Munich, Germany A Hemmerich Hamburg, Germany W Hogervorst Amsterdam, The Netherlands D Kleppner Cambridge, USA C Salomon Paris, France G V Shlyapnikov Amsterdam, Paris, Moscow S Stringari Trento, Italy W Vassen Amsterdam, The Netherlands J T M Walraven Amsterdam, The Netherlands

Vassen, W.; Hemmerich, A.; Arimondo, E.

2003-04-01

261

The Cooling of a Liquid Absorber using a Small Cooler  

SciTech Connect

This report discusses the use of small cryogenic coolers for cooling the Muon Ionization Cooling Experiment (MICE) liquid cryogen absorbers. Since the absorber must be able contain liquid helium as well liquid hydrogen, the characteristics of the available 4.2 K coolers are used here. The issues associated with connecting two-stage coolers to liquid absorbers are discussed. The projected heat flows into an absorber and the cool-down of the absorbers using the cooler are presented. The warm-up of the absorber is discussed. Special hydrogen safety issues that may result from the use of a cooler on the absorbers are also discussed.

Baynham, D.E.; Bradshaw, T.W.; Green, M.A.; Ishimoto, S.; Liggins, N.

2005-08-24

262

Effect of cold acclimatization on exercise economy in the cold.  

PubMed

We sought to determine if cold acclimatized men display higher economy (i.e. lower oxygen consumption at a given workload) during graded cycle ergometry in the cold (5°C). After completing a familiarization trial 1 week prior, five cold weather athletes (CWA) and eight physically active men (NON) underwent graded exercise tests to volitional fatigue in 5°C. The protocol always started at 60 W and increased by 20 W each minute. Oxygen consumption (VO(2)), respiration rate (RR), tidal volume (TV), and respiratory exchange ratio (RER) were determined via open circuit spirometry. Individuals were matched for body size and minutes of weekly physical activity. Repeated measures analyses of variance were conducted across time (workload) and cold acclimatization was entered as a between subjects factor. VO(2) peak was not different between groups but CWA had lower VO(2) at 60 and 240 W. CWA also had lower RR at 180 and 260 W as well as lower RER at 240 and 260 W. At submaximal workloads, cold acclimatized men have higher exercise economy than non-acclimatized men. This could have implications for those who work in this context. PMID:21671101

Muller, Matthew D; Kim, Chul-Ho; Bellar, David M; Ryan, Edward J; Seo, Yongsuk; Muller, Sarah M; Glickman, Ellen L

2012-02-01

263

A tunable EBG absorber for radio-frequency power imaging  

Microsoft Academic Search

Absorption characteristics of a tunable electromagnetic band-gap (EBG) absorber are analyzed, which is designed to capture 2d radio-frequency (RF) power distributions incident on the absorber surface. The EBG absorber has lumped resistors interconnecting the mushroom-type surface patches to absorb the incident RF power at the resonance frequency where the EBG structure exhibits a high-impedance feature. The absorbed RF power distribution

Satoshi Yagitani; Keigo Katsuda; Ryo Tanaka; Masayuki Nojima; Yoshiyuki Yoshimura; Hirokazu Sugiura

2011-01-01

264

Solar Absorber Surfaces Treated by Femtosecond Laser  

Microsoft Academic Search

Using a femtosecond laser surface structuring technique, we produce technologically important solar absorbers (black aluminum, titanium, tungsten, copper, and stainless steel) with absorptance of about 85-95% over a broad wavelength range from ultraviolet to infrared. Scanning electron microscopy shows that the enhanced absorption of the black metals is caused by a rich variety of nano- and microscale surface structures. The

Anatoliy Y. Vorobyev; Chunlei Guo

2010-01-01

265

Absorption strength in absorbing chaotic cavities.  

PubMed

We derive an exact formula to calculate the absorption strength in absorbing chaotic systems such as microwave cavities or acoustic resonators. The formula allows us to estimate the absorption strength as a function of the averaged reflection coefficient and the real coupling parameter. We also define the weak and strong absorption regimes in terms of the coupling parameter and the absorption strength. PMID:18851122

Báez, G; Martínez-Mares, M; Méndez-Sánchez, R A

2008-09-01

266

SUPER ABSORBENT POLYMERS IN ENVIRONMENTAL REMEDIATION  

Microsoft Academic Search

Laboratory studies reported earlier, have shown very promising results in the selective removal of dyes from aqueous solutions by a commercially available (super absorbent polymer) SAP, Jalshakti® (JS). JS is mesoporous in nature and is a potential adsorbent for the basic dyes studied. This paper presents the adsorption and kinetic studies for the Methylene blue dye (MB) in a batch

R. DHODAPKAR; T. NANDY

267

Aldehyde-containing urea-absorbing polysaccharides  

NASA Technical Reports Server (NTRS)

A novel aldehyde containing polymer (ACP) is prepared by reaction of a polysaccharide with periodate to introduce aldehyde groups onto the C2 - C3 carbon atoms. By introduction of ether and ester groups onto the pendant primary hydroxyl solubility characteristics are modified. The ACP is utilized to absorb nitrogen bases such as urea in vitro or in vivo.

Mueller, W. A.; Hsu, G. C.; Marsh, H. E., Jr. (inventors)

1977-01-01

268

Design of a wideband radar absorbing structure  

Microsoft Academic Search

In this paper, a thin planar electromagnetic absorber consisting of two lossy Frequency Selective Surface (FSS) layers is introduced. The layers are separated by foam material and they are backed by the ground plane. Square rings and crossed dipoles are used in the design of these lossy layers. A wideband absorption characteristic is achieved for zero degrees of incidence angle

Egemen Yildirim; Ozlem Aydin Civi

2011-01-01

269

Radiologist and angiographic procedures. Absorbed radiation dose  

Microsoft Academic Search

The radiation dose absorbed by the angiographer during angiographic procedures is of vital importance to the radiologist. Nevertheless, most articles on the subject are incomplete, and few measure gonadal dose. In this study, three TLDs were used for each of the following sites: radiologist's eyes, thyroid, gonads with and without shielding apron, and hands. The average dose during carotid angiograms

MICHAEL TRYHUS; FRED A. METTLER; CHARLES KELSEY

1987-01-01

270

Moving core beam energy absorber and converter  

DOEpatents

A method and apparatus for the prevention of overheating of laser or particle beam impact zones through the use of a moving-in-the-coolant-flow arrangement for the energy absorbing core of the device. Moving of the core spreads the energy deposition in it in 1, 2, or 3 dimensions, thus increasing the effective cooling area of the device.

Degtiarenko, Pavel V.

2012-12-18

271

Estimating the radiation absorbed by a human.  

PubMed

The complexities of the interactions between long- and short-wave radiation fluxes and the human body make it inherently difficult to estimate precisely the total radiation absorbed (R) by a human in an outdoor environment. The purpose of this project was to assess and compare three methods to estimate the radiation absorbed by a human in an outdoor environment, and to compare the impact of applying various skin and clothing albedos (alpha ( h )) on R. Field tests were conducted under both clear and overcast skies to evaluate the performance of applying a cylindrical radiation thermometer (CRT), net radiometer, and a theoretical estimation model to predict R. Three albedos were evaluated: light (alpha ( h ) = 0.57), medium (alpha ( h ) = 0.37), and dark (alpha ( h ) = 0.21). During the sampling periods, the range of error between the methods used to estimate the radiation absorbed by a cylindrical body under clear and overcast skies ranged from 3 to 8%. Clothing and skin albedo had a substantial impact on R, with the mean change in R between the darkest and lightest albedos ranging from 115 to 157 W m( - 2) over the sampling period. Radiation is one of the most important variables to consider in outdoor thermal comfort research, as R is often the largest contributor to the human energy balance equation. The methods outlined and assessed in this study can be conveniently applied to provide reliable estimates of the radiation absorbed by a human in an outdoor environment. PMID:18273649

Kenny, Natasha A; Warland, Jon S; Brown, Robert D; Gillespie, Terry G

2008-07-01

272

Estimating the radiation absorbed by a human  

NASA Astrophysics Data System (ADS)

The complexities of the interactions between long- and short-wave radiation fluxes and the human body make it inherently difficult to estimate precisely the total radiation absorbed ( R) by a human in an outdoor environment. The purpose of this project was to assess and compare three methods to estimate the radiation absorbed by a human in an outdoor environment, and to compare the impact of applying various skin and clothing albedos ( ? h ) on R. Field tests were conducted under both clear and overcast skies to evaluate the performance of applying a cylindrical radiation thermometer (CRT), net radiometer, and a theoretical estimation model to predict R. Three albedos were evaluated: light ( ? h = 0.57), medium ( ? h = 0.37), and dark ( ? h = 0.21). During the sampling periods, the range of error between the methods used to estimate the radiation absorbed by a cylindrical body under clear and overcast skies ranged from 3 to 8%. Clothing and skin albedo had a substantial impact on R, with the mean change in R between the darkest and lightest albedos ranging from 115 to 157 W m - 2 over the sampling period. Radiation is one of the most important variables to consider in outdoor thermal comfort research, as R is often the largest contributor to the human energy balance equation. The methods outlined and assessed in this study can be conveniently applied to provide reliable estimates of the radiation absorbed by a human in an outdoor environment.

Kenny, Natasha A.; Warland, Jon S.; Brown, Robert D.; Gillespie, Terry G.

2008-07-01

273

Novel shock absorber features varying yield strengths  

NASA Technical Reports Server (NTRS)

A shock absorbent webbing of partially drawn synthetic strands is arranged in sections of varying density related to the varying mass of the human body. This is contoured to protect the body at points of contact, when subjected to large acceleration or deceleration forces.

Geier, D. J.

1964-01-01

274

Aircraft Shock Absorber-Landing Gear Retractor.  

National Technical Information Service (NTIS)

An Author Certificate has been issued for a combination shock-absorber and retracting gear for aircraft wheels, which consists of a cylinder with attachment brackets and unions for filling and emptying the working fluid, a piston and a rod with diffusers,...

A. Y. Kogan G. A. Maksimov N. E. Ionov V. N. Bochkarev

1969-01-01

275

How to build a molecular shock absorber.  

PubMed

Newly determined structures of the alpha-helical repeats that make up the key 'rod' domains of spectrin and alpha-actinin - which serve as spacers between their actin-binding domains - have provided important insights into how these proteins function as molecular shock absorbers in cells. PMID:10607557

McGough, A

1999-12-01

276

Shock absorbing mount for electrical components  

NASA Technical Reports Server (NTRS)

A shock mount for installing electrical components on circuit boards is described. The shock absorber is made of viscoelastic material which interconnects the electrical components. With this system, shocks imposed on one component of the circuit are not transmitted to other components. A diagram of a typical circuit is provided.

Dillon, R. F., Jr.; Mayne, R. C. (inventors)

1975-01-01

277

Torus elements used in effective shock absorber  

NASA Technical Reports Server (NTRS)

Energy absorbing device forces torus elements to revolve annularly between two concentric tubes when a load is applied to one tube. Interference forces can be varied by using torus elements of different thicknesses. The device operates repeatedly in compression or tension, and under problems of large onset rate tolerance or structural overload.

Cunningham, P.; Platus, D. L.

1966-01-01

278

Comparison between semiclassical and composite absorbing potentials  

NASA Astrophysics Data System (ADS)

We compare the absorption of (a) an absorbing potential proposed recently by Manolopoulos based on semiclassical arguments and (b) complex potentials composed by contiguous square barriers. The latter use more parameters and provide better absorption, but the potential by Manolopoulos is simple and robust with respect to numerical discretization, and can be very efficient if its only effective parameter is optimized.

Muga, J. G.; Navarro, B.

2004-06-01

279

Collapsible impact energy absorbers: an overview  

Microsoft Academic Search

This paper reviews the common shapes of collapsible energy absorbers and the different modes of deformation of the most common ones. Common shapes include circular tubes, square tubes, frusta, struts, honeycombs, and sandwich plates. Common modes of deformation for circular tubes include axial crushing, lateral indentation, lateral flattening, inversion and splitting. Non-collapsible systems, such as lead extrusions or tube expansions,

A. A. A Alghamdi

2001-01-01

280

Energy absorbing hybrid nano-composite materials  

Microsoft Academic Search

Base Epon 862 resin was enhanced with two types of fillers, graphitized carbon nanofiber (CNF) and silicon dioxide (SiO2) particles. The effect of both filler type and filler loading were investigated with respect to the energy absorbing capacity as well as the thermal stability of the hybrid composite material, measured in terms of the coefficient of thermal expansion (CTE). As

Jae-Soon Jang; Joshua Varischetti; Gyo Woo Lee; Jonghwan Suhr

2009-01-01

281

Shock absorber protects motive components against overloads  

NASA Technical Reports Server (NTRS)

Shock absorber with an output shaft, hollow gear, and a pair of springs forming a resilient driving connection between shaft and gear, operates when abnormally high torques are applied. This simple durable frictional device is valuable in rotating mechanisms subject to sudden overloads.

1965-01-01

282

ANL Advanced Photon Source crotch absorber design.  

National Technical Information Service (NTIS)

The ANL 7-GeV Advanced Photon Source storage ring crotch absorber will be subjected to a very high photon loading power density, approximately 750 W/mm(sup 2) at normal incidence. To accommodate this high heat load, two designs were studied: one is a V-ty...

M. Choi J. D. Gonczy J. W. Howell R. C. Niemann

1991-01-01

283

Absorbing boundaries in the conserved Manna model  

NASA Astrophysics Data System (ADS)

The conserved Manna model with a planar absorbing boundary is studied in various space dimensions. We present a heuristic argument that allows one to compute the surface-critical exponent in one dimension analytically. Moreover, we discuss the mean-field limit that is expected to be valid in d>4 space dimensions and demonstrate how the corresponding partial differential equations can be solved.

Hipke, Arthur; Lübeck, Sven; Hinrichsen, Haye

2009-07-01

284

Application and Durability of Solar Absorber Coatings.  

National Technical Information Service (NTIS)

The suitability of solar absorber coatings for use as the thermal power source to drive spaceborne Vuilleumier cycle cryogenic refrigerators was evaluated. The coating tested consisted of layers of A12O3-Mo-A12O3 (AMA) on various substrates. The coating w...

J. W. Ramsey R. E. Peterson

1973-01-01

285

Composition for absorbing hydrogen from gas mixtures  

DOEpatents

A hydrogen storage composition is provided which defines a physical sol-gel matrix having an average pore size of less than 3.5 angstroms which effectively excludes gaseous metal hydride poisons while permitting hydrogen gas to enter. The composition is useful for separating hydrogen gas from diverse gas streams which may have contaminants that would otherwise render the hydrogen absorbing material inactive.

Heung, Leung K. (Aiken, SC); Wicks, George G. (Aiken, SC); Lee, Myung W. (Aiken, SC)

1999-01-01

286

Absorption enhancement of fractal frequency selective surface absorbers by using microwave absorbing material based substrates  

NASA Astrophysics Data System (ADS)

In this paper, the effect of microwave absorbing material-based (MAM) substrate on the absorption properties of fractal frequency selective surface (FSS) absorbers was investigated in detail. The fractal shapes were proposed to construct the schematic diagrams of the FSS unit cell. The absorption properties of the absorber samples containing different substrates, including FR-4dielectric substrate and MAM-based substrate, were exhibited via the Naval Research Laboratory (NRL)-arch method, respectively. Then the power loss density distributions of the absorbers were illustrated by the finite integration technology (FIT) method to obtain an insight of the physical picture into the absorption properties. The results indicate that with the increase of the substrate thicknesses, the FR-4-based FSS absorbers could achieve the strongest absorbing performance at a certain thickness. However, employing the MAM-based substrate to replace the FR-4 substrate with the same substrate thickness enhances the absorbing properties greatly, including the peak values and the bandwidths. As a result, the way of introducing the MAM-based substrates instead of the traditional dielectric substrates provides a potential practical application in device miniaturization.

Liao, Zhangqi; Gong, Rongzhou; Nie, Yan; Wang, Tao; Wang, Xian

2011-07-01

287

Absorbing properties and structural design of microwave absorbers based on carbonyl iron and barium ferrite  

NASA Astrophysics Data System (ADS)

Carbonyl iron and barium ferrite powder (BaZn 1.5Co 0.5Fe 16O 27) were prepared in this work. The complex permittivity and permeability spectra for rubber radar absorbing materials employing carbonyl iron and barium ferrite powders were measured. A database describing the frequency dependence of the permittivities and permeabilities of the carbonyl iron and barium ferrite microwave absorbers with various powder percentage compositions in 2-18 GHz was created. Based on the database, the single-layer and double-layer absorbers were designed and prepared, and their microwave absorption properties were investigated. The results indicate that the carbonyl iron powder prepared via thermal decomposition of iron pentacarbonyl is single cubic iron and of spherical shape. The barium ferrite powder is single W-type ferrite and a hexagonal flake. The absorption band of the double-layer microwave absorber is obviously more than that of the single-layer absorber. The double-layer microwave absorbers with reflection loss <-13 dB over the range of 6-18 GHz and reflection loss <-8 dB over the range of 2-18 GHz were prepared. The thicknesses of the absorbers are only 3.6 and 3.7 mm, respectively.

Feng, Y. B.; Qiu, T.; Shen, C. Y.

2007-11-01

288

Radiative and climate impacts of absorbing aerosols  

NASA Astrophysics Data System (ADS)

By integrating experimental data, radiative transfer theory, and numerical modelling, this dissertation aims to improve our understanding of the radiative and the climate impacts of the major absorbing aerosols: mineral dust, black carbon (BC) and brown carbon. The research presented here combines existing surface, satellite and aircraft measurements and develops self-consistent models for aerosol mixing state, global and regional radiative forcing of absorbing aerosols and their climate effects. The first part of this dissertation presents the climatology and radiative impacts of dust plumes over the Pacific, the Indian and the Atlantic Oceans using multiple satellite datasets in conjunction with MACR (Monte Carlo Aerosol-Cloud-Radiation) model. A core-shell internally mixed aerosol model has been developed using the microphysical, chemical, and radiative observations as constraints. It is shown that internal mixing enhances the aerosol absorption and contributes to over 20% increase of radiative forcing. The aerosol mixing model is validated by comparing model simulated spectrally-resolved irradiance with observations. The results show that aerosol induced forcing is mainly confined in the visible band and the largest forcing occurs in the blue channel. Having validated the modelling of the mixing-state of absorbing aerosols with broadband and high-resolution spectral radiation data, global three-dimensional distribution of the spectral radiative forcing is obtained. The aerosol forcing is used to drive a general circulation model (GCM) with prescribed sea surface temperature to investigate the impact of absorbing aerosols on regional climate. One of the main model findings is that heating of the atmosphere by absorbing aerosols can contribute to significant reductions in low level clouds, which in turn amplifies the warming. The simulated cloudiness reduction is particularly strong over the Arctic and China and the simulated warming over the Arctic exceeds 1.5°C. The findings of cloud reduction over China and the warming over the Arctic are consistent with observations. The above effects are relatively weak or negligible when absorbing aerosols are treated as externally mixed which is used as the assumption by most GCM studies thus far. This study reveals the fundamental importance of accounting for the observed chemical and physical properties of absorbing aerosols.

Zhu, Aihua

289

Mathematical modeling of cold cap  

NASA Astrophysics Data System (ADS)

The ultimate goal of studies of cold cap behavior in glass melters is to increase the rate of glass processing in an energy-efficient manner. Regrettably, mathematical models, which are ideal tools for assessing the responses of melters to process parameters, have not paid adequate attention to the cold cap. In this study, we consider a cold cap resting on a pool of molten glass from which it receives a steady heat flux while temperature, velocity, and extent of conversion are functions of the position along the vertical coordinate. A one-dimensional mathematical model simulates this process by solving the differential equations for mass and energy balances with appropriate boundary conditions and constitutive relationships for material properties. The sensitivity analyses on the effects of incoming heat fluxes to the cold cap through its lower and upper boundaries show that the cold cap thickness increases as the heat flux from above increases, and decreases as the total heat flux increases. We also discuss the effects of foam, originating from batch reactions and from redox reactions in molten glass, and argue that models must represent the foam layer to achieve a reliable prediction of the melting rate as a function of feed properties and melter conditions.

Pokorny, Richard; Hrma, Pavel

2012-10-01

290

Treatment of the common cold.  

PubMed

The common cold is a viral illness that affects persons of all ages, prompting frequent use of over-the-counter and prescription medications and alternative remedies. Treatment focuses on relieving symptoms (e.g., cough, nasal congestion, rhinorrhea). Dextromethorphan may be beneficial in adults with cough, but its effectiveness has not been demonstrated in children and adolescents. Codeine has not been shown to effectively treat cough caused by the common cold. Although hydrocodone is widely used and has been shown to effectively treat cough caused by other conditions, the drug has not been studied in patients with colds. Topical (intranasal) and oral nasal decongestants have been shown to relieve nasal symptoms and can be used in adolescents and adults for up to three days. Antihistamines and combination antihistamine/decongestant therapies can modestly improve symptoms in adults; however, the benefits must be weighed against potential side effects. Newer nonsedating antihistamines are ineffective against cough. Topical ipratropium, a prescription anticholinergic, relieves nasal symptoms in older children and adults. Antibiotics have not been shown to improve symptoms or shorten illness duration. Complementary and alternative therapies (i.e., Echinacea, vitamin C, and zinc) are not recommended for treating common cold symptoms; however, humidified air and fluid intake may be useful without adverse side effects. Vitamin C prophylaxis may modestly reduce the duration and severity of the common cold in the general population and may reduce the incidence of the illness in persons exposed to physical and environmental stresses. PMID:17323712

Simasek, Madeline; Blandino, David A

2007-02-15

291

Application of manganese dioxide to electromagnetic wave absorber: effective permittivity and absorbing property  

NASA Astrophysics Data System (ADS)

This paper presents the application of manganese dioxide to electromagnetic wave absorber. The effective permittivity was calculated by modified Rayleigh mixing formula, and the electromagnetic wave absorbing properties of composites with different volume fractions of manganese dioxide were investigated by the comparison of calculated and experimental values in 2 12GHz frequencies. It is found that the pure manganese dioxide holds a high dielectric constant, which is a function of frequency. The manganese dioxide composites show high absorbing performance in low frequencies, and the calculated electromagnetic properties fit the experimental values for large volume fractions used in this study.

Guan, H.; Zhao, Y.; Liu, S.; Lv, S.

2006-12-01

292

Spectral absorbance of benthic cladoceran carapaces as a new method for inferring past UV exposure of aquatic biota  

NASA Astrophysics Data System (ADS)

We developed a method for measuring fossil cladoceran (Branchiopoda) carapace absorbance to infer past ultraviolet radiation (UV) exposure in lakes. This was done under the presumptions that cladocerans synthesize photoprotective compounds, of which melanin is the main UV-absorbing pigment, to their exoskeletons and melanin is preserved in sedimentary cladoceran remains. We extracted large-sized cladoceran (benthic Alona spp.) carapaces from subsections of sediment cores from two environmentally divergent lakes; a humic boreal forest lake in eastern Finland (past 1500 years) and a clear-water mountain lake in the Austrian Alps (past 300 years). We measured the absorbance of extracted carapaces with a spectrophotometer under visible light and UV wavelengths using an adapter, which was designed to hold the microfossils. When compared to the spectrum of synthetic melanin, the shapes of absorbance spectra at the 700-280 nm range suggested that the fossil carapaces contained melanin. The carapace absorbance under UV throughout the sediment cores was significantly higher in the clear-water alpine lake than in the humic boreal lake reflecting differences in the general underwater UV and optical environments between the sites. In addition, carapace absorbance was significantly higher during the Little Ice Age (LIA) than during pre- or post-LIA periods in both lakes. In the alpine lake, this was most likely a response to increased underwater UV induced by reduced primary production and more transparent water column during the cold summers of LIA, whereas reduced input of carbon compounds from the catchment through elongated permafrost and ice-cover periods likely induced higher water transparency in the boreal lake during this cold climate phase. We conclude that fossil melanin provides a good estimation of past underwater UV exposure in lakes with large cladoceran carapaces preserved in sediments and that the method introduced here is easy and cost- and time-efficient technique to be widely used in paleoaquatic UV inferences.

Nevalainen, Liisa; Rautio, Milla

2014-01-01

293

COLD-SAT dynamic model  

NASA Technical Reports Server (NTRS)

This report discusses the development and underlying mathematics of a rigid-body computer model of a proposed cryogenic on-orbit liquid depot storage, acquisition, and transfer spacecraft (COLD-SAT). This model, referred to in this report as the COLD-SAT dynamic model, consists of both a trajectory model and an attitudinal model. All disturbance forces and torques expected to be significant for the actual COLD-SAT spacecraft are modeled to the required degree of accuracy. Control and experimental thrusters are modeled, as well as fluid slosh. The model also computes microgravity disturbance accelerations at any specified point in the spacecraft. The model was developed by using the Boeing EASY5 dynamic analysis package and will run on Apollo, Cray, and other computing platforms.

Adams, Neil S.; Bollenbacher, Gary

1992-01-01

294

Insight into the Nonlinear Absorbance of Two Related Series of Two- Photon Absorbing Chromophores (Preprint).  

National Technical Information Service (NTIS)

A comprehensive photophysical study has been carried out on two series of two-photon absorbing dyes. Looking at a series of structurally related chromophores provides insight into what controls the linear and nonlinear photophysical properties. These mate...

J. E. Rogers J. E. Slagle L. Tan P. A. Fleitz R. Jakubiak

2006-01-01

295

Varmepumpe med energiabsorber som varmeoptager. (Heat pumps and energy-absorber as heat absorbers).  

National Technical Information Service (NTIS)

With regard to heat pumps with uncovered solar collectors as the only heat absorbers, very high temperatures (> 50 deg. centigrade) can arise in the latter during the summer. Other problems are constructional damage when the solar collector is integrated ...

H. C. Aagaard

1992-01-01

296

Design of a non-traditional dynamic vibration absorber.  

PubMed

A non-traditional dynamic vibration absorber is proposed for the minimization of maximum vibration velocity response of a vibrating structure. Unlike the traditional damped absorber configuration, the proposed absorber has a linear viscous damper connecting the absorber mass directly to the ground instead of the main mass. Optimum parameters of the proposed absorber are derived based on the fixed-point theory for minimizing the maximum vibration velocity response of a single-degree-of-freedom system under harmonic excitation. The extent of reduction in maximum vibration velocity response of the primary system when using the traditional dynamic absorber is compared with that using the proposed one. Under the optimum tuning condition of the absorbers, it is proved analytically that the proposed absorber provides a greater reduction in maximum vibration velocity response of the primary system than the traditional absorber. PMID:19640019

Cheung, Y L; Wong, W O

2009-08-01

297

a Standing-Wave Sloshing Absorber to Control Transient Oscillations  

NASA Astrophysics Data System (ADS)

The primary purpose of this study is to introduce a sloshing absorber as a practical alternative to the damped tuned absorber. In addition, a numerical simulation procedure is introduced as a computer-aided design tool. The problem of interest is the control of excessive oscillations of a mechanical oscillator in response to an initial displacement. Tuned vibration absorbers are frequently used for this purpose, and if damping is included in the tuned absorber, control action is quite effective. The problem, however, is that inclusion of an energy dissipation element necessitates frequent maintenance in practice. The suggested control technique here is a sloshing absorber, in place of the damped tuned vibration absorber. In contrast to a tuned absorber, a sloshing absorber accomplishes energy dissipation through sloshing. Therefore, it may be virtually maintenance free. Also for practical applications, this type of absorber can be an advantage where existing water storage tanks can be modified to control vibrations of the supporting structure.

ANDERSON, J. G.; SEMERCIGIL, S. E.; TURAN, Ö. F.

2000-05-01

298

Antihydrogen Formation using Cold Plasmas  

SciTech Connect

Antihydrogen, the antimatter counterpart of the hydrogen atom, can be formed by mixing cold samples of antiprotons and positrons. In 2002 the ATHENA collaboration succeeded in the first production of cold antihydrogen. By observing and imaging the annihilation products of the neutral, non-confined, antihydrogen atoms annihilating on the walls of the trap we can observe the production in quasi-real-time and study the dynamics of the formation mechanism. The formation mechanism strongly influences the final state of the formed antihydrogen atoms, important for future spectroscopic comparison with hydrogen. This paper briefly summarizes the current understanding of the antihydrogen formation in ATHENA.

Madsen, N.; Bowe, P.D.; Hangst, J.S. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); Amoretti, M.; Carraro, C.; Macri, M.; Testera, G.; Variola, A. [Istituto Nazionale di Fisica Nucleare, Sezione di Genova, I-16146 Genova (Italy); Amsler, C.; Johnson, I.; Pruys, H.; Regenfus, C. [Physik-Institut, Zuerich University, CH-8057 Zurich (Switzerland); Bonomi, G.; Bouchta, A.; Doser, M.; Kellerbauer, A.; Landua, R. [PH Department, CERN, Geneva (Switzerland); Cesar, C.L. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21945-970 (Brazil); Charlton, M.; Joergensen, L.V. [Department of Physics, University of Wales Swansea, Swansea SA2 8PP (United Kingdom)] [and others

2004-10-20

299

Fabrication of multi-pixel TES microcalorimeters with an electrodeposited Sn absorber and Bi absorber  

Microsoft Academic Search

We have developed multi-pixel TES microcalorimeters in order to realize high-energy resolution and X-ray imaging. A Sn absorber and a Bi absorber were formed on Si3N4 and SiO2 membrane using two-step exposure photolithography and electrodeposition. A FEM analysis was carried out to investigate the performance of the X-ray microabsorbers. In addition, a superconducting through-wafer interconnection was demonstrated considering the future

T. Arakawa; H. Kudo; H. Sato; H. Kobayashi; T. Izumi; S. Ohtsuka; K. Mori; S. Shoji; T. Osaka; T. Homma; K. Mitsuda; N. Yamasaki; R. Fujimoto; N. Iyomoto; T. Oshima; K. Futamoto; Y. Takei; T. Ichitsubo; T. Fujimori; K. Yoshida; Y. Ishisaki; U. Morita; T. Koga; K. Shinozaki; K. Sato; N. Takai; T. Ohashi; Y. Kuroda; M. Onishi; M. Goto; F. Beppu

2004-01-01

300

Cold accretion flows and the nature of high column density H I absorption at redshift 3  

NASA Astrophysics Data System (ADS)

Simulations predict that galaxies grow primarily through the accretion of gas that has not gone through an accretion shock near the virial radius and that this cold gas flows towards the central galaxy along dense filaments and streams. There is, however, little observational evidence for the existence of these cold flows. We use a large, cosmological, hydrodynamical simulation that has been post-processed with radiative transfer to study the contribution of cold flows to the observed z= 3 column density distribution of neutral hydrogen, which our simulation reproduces. We find that nearly all of the H I absorption arises in gas that has remained colder than 105.5 K, at least while it was extragalactic. In addition, the majority of the H I is falling rapidly towards a nearby galaxy, with non-negligible contributions from outflowing and static gas. Above a column density of ? cm-2, most of the absorbers reside inside haloes, but the interstellar medium only dominates for ? cm-2. Haloes with total mass below 1010 M? dominate the absorption for ? cm-2, but the average halo mass increases sharply for higher column densities. Although very little of the H I in absorbers with ? cm-2 resides inside galaxies, systems with ? cm-2 are closely related to star formation: most of their H I either will become part of the interstellar medium before z= 2 or has been ejected from a galaxy at z > 3. Cold accretion flows are critical for the success of our simulation in reproducing the observed rate of incidence of damped Lyman-? and particularly that of Lyman limit systems. We therefore conclude that cold accretion flows exist and have already been detected in the form of high column density H I absorbers.

van de Voort, Freeke; Schaye, Joop; Altay, Gabriel; Theuns, Tom

2012-04-01

301

HDPE/MWCNT composite as microwave absorber  

NASA Astrophysics Data System (ADS)

A HDPE/CNT composite has been fabricated based on a commercial polyethylene loaded with a high concentration of CVD grown multiwalled carbon nanotubes with a high aspect ratio. Exploiting the resulting high conductivity of this composite material, we tested the possibility to use it as absorber of electromagnetic waves at microwave frequencies up to 25 GHz. For this purpose the device under test was placed as substrate of a microstrip transmission line. Measurements of the scattering parameters, done with a vectorial network analyzer, have been used in order to obtain the power absorption at different frequencies. Special attention was paid to the optimization of the microstrip geometry. A comparison of the microwave power absorption spectrum with those of commercial cavity absorbers showed encouraging results, regarding the microwave absorption capability of the HDPE/CNT composite material.

Di Giacomo, R.; Neitzert, H. C.

2014-05-01

302

Investigations on Absorber Materials at Cryogenic Temperatures  

SciTech Connect

In the framework of the 12 GeV upgrade project for the Continuous Electron Beam Accelerator Facility (CEBAF) improvements are being made to refurbish cryomodules housing Thomas Jefferson National Accelerator Facility?s (JLab) original 5-cell cavities. Recently we have started to look into a possible simplification of the existing Higher Order Mode (HOM) absorber design combined with the aim to find alternative material candidates. The absorbers are implemented in two HOM-waveguides immersed in the helium bath and operate at 2 K temperature. We have built a cryogenic setup to perform measurements on sample load materials to investigate their lossy characteristics and variations from room temperature down to 2 K. Initial results are presented in this paper.

Frank Marhauser, Thomas Elliott, Robert Rimmer

2009-05-01

303

Shock wave absorber having apertured plate  

DOEpatents

The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

Shin, Yong W. (Western Springs, IL); Wiedermann, Arne H. (Chicago Heights, IL); Ockert, Carl E. (Vienna, VA)

1985-01-01

304

Water-absorbing balls: a "growing" problem.  

PubMed

Foreign body ingestion is a potentially serious clinical problem in children. We report a case of an 8-month-old infant who developed complete bowel obstruction requiring laparotomy due to ingestion of a superabsorbent polymer ball with advertised growth up to 400 times its original size. Most ingested foreign bodies that pass through the pylorus will make it safely through the gastrointestinal tract. This is not true for water-absorbing balls that progressively increase in size and cause intestinal obstruction. Other household products and toys on the market use a similar polymer-based water-absorbing technology, thus increasing the risk for accidental ingestion by young children. These rapidly expanding objects can cause significant morbidity, and timely diagnosis and treatment are prudent to improve patient outcomes. PMID:22987870

Zamora, Irving J; Vu, Lan T; Larimer, Emily L; Olutoye, Oluyinka O

2012-10-01

305

Anomalous retroreflection from strongly absorbing nanoporous semiconductors.  

PubMed

Pronounced retroreflection behavior is reported for a fishnet nanoporous strongly absorbing semiconductor material. Retroreflection features a half-cone about 0.35 rad along with diffusive specular reflection for all angles of incidence. Retroreflection is apparent by the naked eye with daylight illumination and exhibits no selectivity with respect to wavelength and polarization of incident light featuring minor depolarization of retroreflected light. The reflectance in the backward direction measures 12% with respect to a white scattering etalon. The phenomenon can be classified neither as coherent backscattering nor as Anderson localization of light. The primary model includes light scattering from strongly absorptive and refractive superwavelength clusters existing within the porous fishnet structure. A reasonable qualitative explanation is based on the fact that strict retroreflection obeys shorter paths inside absorbing medium, whereas all alternative paths will lead to stronger absorption of light. PMID:21847216

Prislopski, S Ya; Naumenko, E K; Tiginyanu, I M; Ghimpu, L; Monaico, E; Sirbu, L; Gaponenko, S V

2011-08-15

306

Shock wave absorber having apertured plate  

DOEpatents

The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

Shin, Y.W.; Wiedermann, A.H.; Ockert, C.E.

1983-08-26

307

Anomalous retroreflection from strongly absorbing nanoporous semiconductors  

NASA Astrophysics Data System (ADS)

Pronounced retroreflection behavior is reported for a fishnet nanoporous strongly absorbing semiconductor material. Retroreflection features a half-cone about 0.35rad along with diffusive specular reflection for all angles of incidence. Retroreflection is apparent by the naked eye with daylight illumination and exhibits no selectivity with respect to wavelength and polarization of incident light featuring minor depolarization of retroreflected light. The reflectance in the backward direction measures 12% with respect to a white scattering etalon. The phenomenon can be classified neither as coherent backscattering nor as Anderson localization of light. The primary model includes light scattering from strongly absorptive and refractive superwavelength clusters existing within the porous fishnet structure. A reasonable qualitative explanation is based on the fact that strict retroreflection obeys shorter paths inside absorbing medium, whereas all alternative paths will lead to stronger absorption of light.

Prislopski, S. Ya.; Naumenko, E. K.; Tiginyanu, I. M.; Ghimpu, L.; Monaico, E.; Sirbu, L.; Gaponenko, S. V.

2011-08-01

308

Passenger Car and Light Truck Shock Absorber Inspection Equipment. Volume 2. Technical Report.  

National Technical Information Service (NTIS)

Contents: Literature survey; Shock absorber degradation and its effect upon vehicle handling; Shock absorber survey; Shock absorber testing; Boge shocktester; Hunter F-11A shockometer; Koni suspension tester; Sama shock absorber tester; Other shock absorb...

R. D. Wooten

1975-01-01

309

Wide band cryogenic ultra-high vacuum microwave absorber  

DOEpatents

An absorber waveguide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the waveguide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the waveguide. 11 figs.

Campisi, I.E.

1992-05-12

310

Wide band cryogenic ultra-high vacuum microwave absorber  

DOEpatents

An absorber wave guide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the wave guide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the wave guide.

Campisi, Isidoro E. (Newport News, VA)

1992-01-01

311

Control of a dynamic vibration absorber with magnetorheological damping  

NASA Astrophysics Data System (ADS)

Two control techniques are explored analytically for a dynamic vibration absorber with a magnetorheological fluid damper replacing the absorber dashpot. The approaches include skyhook control and an approximation to a linear quadratic optimal control. The approximate-optimal control, which attempts to match the magnetorheological damper force to an optimal control force based on a linear absorber, is shown to improve the dymanic absorber performance over a substantial range of excitation frequencies and force levels, while the skyhook approach is less successful. Detuning the absorber natural frequency below the optimal detuning for a linear absorber improves performance in the approximate- optimal case.

Vavreck, Andrew N.

2000-08-01

312

Preparation of perlite-based carbon dioxide absorbent.  

PubMed

A new highly efficient carbon dioxide absorbent consisting of sodium hydroxide, expanded perlite and acid-base indicator was prepared. The absorption efficiency, absorption capacity, flow resistance and color indication for the absorbent were tested and compared with some commercial products. The absorbent can reduce the carbon dioxide content in gases to 3.3 ppb (v/v) and absorbs not less than 35% of its weight of carbon dioxide. Besides its large capacity and sharp color indication, the absorbent has an outstanding advantage of small flow resistance in comparison with other commercial carbon dioxide absorbents. Applications in gas analysis and purification were also investigated. PMID:18965919

He, H; Wu, L; Zhu, J; Yu, B

1994-02-01

313

Quasar Absorbers and Large Scale Structure  

Microsoft Academic Search

We propose STIS spectroscopy of 15 bright {V < 18} quasars in a 22 square degree region that has well-sampled galaxy redshifts. This is a unique asterism of quasars of this brightness. The spectra will yield 183 Lyman-alpha absorbers, 119 of which will be in the range 0 < z < 0.2, with rest equivalent widths complete to 0.21 Angstroms.

Chris Impey

2001-01-01

314

Design and Manufacture of Energy Absorbing Materials  

ScienceCinema

Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

Duoss, Eric

2014-05-30

315

Tech Transfer Webinar: Energy Absorbing Materials  

ScienceCinema

A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

Duoss, Eric

2014-07-15

316

Trends in radar absorbing materials technology  

Microsoft Academic Search

The research in the area of Radar Absorbing Materials (RAMs) has been actively pursued for at least four decades. Although\\u000a resonant RAMs were originally designed by transmission line approach, and the broad band RAMs were obtained by multilayering,\\u000a the quest for ultrawide band performance has led to novel approaches such as chirality and even exploring biochemical products.\\u000a It is observed

K J Vinoy; R M Jha

1995-01-01

317

Lightweight Energy Absorbers for Blast Containers  

NASA Technical Reports Server (NTRS)

Kinetic-energy-absorbing liners made of aluminum foam have been developed to replace solid lead liners in blast containers on the aft skirt of the solid rocket booster of the space shuttle. The blast containers are used to safely trap the debris from small explosions that are initiated at liftoff to sever frangible nuts on hold-down studs that secure the spacecraft to a mobile launch platform until liftoff.

Balles, Donald L.; Ingram, Thomas M.; Novak, Howard L.; Schricker, Albert F.

2003-01-01

318

Nonlinear vibrations of hydraulic shock absorbers  

NASA Astrophysics Data System (ADS)

A method of equivalent linearization for a nonlinear dynamic system of vibrations with a hydraulically elastic shock absorber is presented. An integral estimation of the exact and approximate solutions is obtained. It is shown that with an appropriate choice of the parameter ? the linearized dynamic system differs insignificantly from the nonlinear one. The influence of nonlinear factors on the coefficients of the dynamic rigidity and transmission has been established. These results agree well with the experimental curves published in the foreign scientific literature.

Dokukova, N. A.; Martynenko, M. D.; Kaftaikina, E. N.

2008-11-01

319

Microcellular ceramic foams for radar absorbing structures  

Microsoft Academic Search

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of this project is to develop a lightweight, semi-structural, radar-absorbing ceramic foam that can be incorporated into aircraft exhaust systems to replace many of the currently used dense ceramic parts and thereby improve the radar cross section.

J. Huling; D. Phillips

1996-01-01

320

BIOCHEMISTRY: An Absorbing Study of Cholesterol  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. We obtain sterols from the animal and plant food that we eat. How these plant and animal sterols are absorbed, transported around the body, and excreted has been the subject of much investigation. In a Perspective, Allayee and colleagues discuss a new study (Berge et al.) that implicates two new ABC transporter proteins in the efflux of plant and animal sterols from gut epithelial cells into the gut lumen.

Hooman Allayee (University of California, Los Angeles (UCLA) School of Medicine;Department of Medicine and the Department of Microbiology, Immunology and Molecular Genetics); Bryan A. Laffitte (University of California, Los Angeles (UCLA) School of Medicine;Howard Hughes Medical Institute); Aldons J. Lusis (University of California, Los Angeles (UCLA) School of Medicine;Department of Medicine and the Department of Microbiology, Immunology and Molecular Genetics)

2000-12-01

321

EMAS Cold Weather Performance Investigations.  

National Technical Information Service (NTIS)

At some airports, Engineered Material Arresting Systems (EMAS) are used in runway safety areas at to provide a mechanism for decelerating aircraft in the event of a runway overrun. The main component of an EMAS is energy-absorbing cellular concrete materi...

B. A. Coutermarsh

2009-01-01

322

Load limiting energy absorbing lightweight debris catcher  

NASA Technical Reports Server (NTRS)

In the representative embodiment of the invention disclosed, a load limiting, energy absorbing net is arranged to overlay a normally-covered vent opening in the rear bulkhead of the space orbiter vehicle. Spatially-disposed flexible retainer straps are extended from the net and respectively secured to bulkhead brackets spaced around the vent opening. The intermediate portions of the straps are doubled over and stitched together in a pattern enabling the doubled-over portions to progressively separate at a predicable load designed to be well below the tensile capability of the straps as the stitches are successively torn apart by the forces imposed on the retainer members whenever the cover plate is explosively separated from the bulkhead and propelled into the net. By arranging these stitches to be successively torn away at a load below the strap strength in response to forces acting on the retainers that are less than the combined strength of the retainers, this tearing action serves as a predictable compact energy absorber for safely halting the cover plate as the retainers are extended as the net is deployed. The invention further includes a block of an energy-absorbing material positioned in the net for receiving loose debris produced by the explosive release of the cover plate.

Kahn, Jon B. (inventor); Schneider, William C. (inventor)

1991-01-01

323

Development of monofilar rotor hub vibration absorber  

NASA Technical Reports Server (NTRS)

A design and ground test program was conducted to study the performance of the monofilar absorber for vibration reduction on a four-bladed helicopter. A monofilar is a centrifugal tuned two degree-of-freedom rotor hub absorber that provides force attenuation at two frequencies using the same dynamic mass. Linear and non-linear analyses of the coupled monofilar/airframe system were developed to study tuning and attenuation characteristics. Based on the analysis, a design was fabricated and impact bench tests verified the calculated non-rotating natural frequencies and mode shapes. Performance characteristics were measured using a rotating absorber test facility. These tests showed significant attenuation of fixed-system 4P hub motions due to 3P inplane rotating-system hub forces. In addition, detuning effects of the 3P monofilar modal response were small due to the nonlinearities and tuning pin slippage. However, attenuation of 4P hub motions due to 5P inplane hub forces was poor. The performance of the 5P monofilar modal response was degraded by torsional motion of the dynamic mass relative to the support arm which resulted in binding of the dynamic components. Analytical design studies were performed to evaluate this torsional motion problem. An alternative design is proposed which may alleviate the torsional motion of the dynamic mass.

Duh, J.; Miao, W.

1983-01-01

324

Cosmic Dust in Mg II Absorbers  

NASA Astrophysics Data System (ADS)

Mg II absorbers induce reddening on background quasars. We measure this effect and infer the cosmic density of dust residing in these systems to be ? ? 2 × 10-6, in units of the critical density of the universe, which is comparable to the amount of dust found in galactic disks or about half the amount inferred to exist outside galaxies. We also estimate the neutral hydrogen abundance in Mg II clouds to be ? ? 1.5 × 10-4, which is approximately 5% of hydrogen in stars in galaxies. This implies a dust-to-gas mass ratio for Mg II clouds of about 1/100, which is similar to the value for normal galaxies. This would support the hypothesis of the outflow origin of Mg II clouds, which are intrinsically devoid of stars and hence have no sources of dust. Considerations of the dust abundance imply that the presence of Mg II absorbers around galaxies lasts effectively for a few Gyr. High-redshift absorbers allow us to measure the rest-frame extinction curve to 900 Å, at which the absorption by the Lyman edge dominates over scattering by dust in the extinction opacity.

Ménard, Brice; Fukugita, Masataka

2012-08-01

325

COSMIC DUST IN Mg II ABSORBERS  

SciTech Connect

Mg II absorbers induce reddening on background quasars. We measure this effect and infer the cosmic density of dust residing in these systems to be {Omega} Almost-Equal-To 2 Multiplication-Sign 10{sup -6}, in units of the critical density of the universe, which is comparable to the amount of dust found in galactic disks or about half the amount inferred to exist outside galaxies. We also estimate the neutral hydrogen abundance in Mg II clouds to be {Omega} Almost-Equal-To 1.5 Multiplication-Sign 10{sup -4}, which is approximately 5% of hydrogen in stars in galaxies. This implies a dust-to-gas mass ratio for Mg II clouds of about 1/100, which is similar to the value for normal galaxies. This would support the hypothesis of the outflow origin of Mg II clouds, which are intrinsically devoid of stars and hence have no sources of dust. Considerations of the dust abundance imply that the presence of Mg II absorbers around galaxies lasts effectively for a few Gyr. High-redshift absorbers allow us to measure the rest-frame extinction curve to 900 A, at which the absorption by the Lyman edge dominates over scattering by dust in the extinction opacity.

Menard, Brice [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Fukugita, Masataka [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8583 (Japan)

2012-08-01

326

Application of magnetorheological elastomer to vibration absorber  

NASA Astrophysics Data System (ADS)

Traditional dynamic vibration absorber (DVA) is widely used in industries as a vibration absorption equipment. However, it is only effective at narrow working frequency range. This shortcoming has limited its stability and application. This paper develops an adaptive tuned vibration absorber (ATVA) based on unique characteristics of magnetorheological elastomers (MREs), whose modulus can be controlled by an applied magnetic field. This ATVA works in shear mode and consists of dynamic mass, static mass and smart spring elements with MREs. Based on the double pole model of MR effects, the shift-frequency capability of the ATVA has been theoretically and experimentally evaluated. The experimental results demonstrated that the natural frequency of the ATVA can be tuned from 27.5 Hz to 40 Hz. To study its vibration absorption capacity, a beam structure with two ends supported has been employed. To analyze the vibration absorption capacity, a dynamic model of coupling beam and absorber has been established. Both the calculation and experimental results show that the absorption capacity of the developed ATVA is better than the traditional TVA and can achieve as high as 25 dB which was justified by the experiment.

Deng, Hua-xia; Gong, Xing-long

2008-11-01

327

An absorbed dose calorimeter for IMRT dosimetry  

NASA Astrophysics Data System (ADS)

A new calorimeter for dosimetry in small and complex fields has been built. The device is intended for the direct determination of absorbed dose to water in moderately small fields and in composite fields such as IMRT treatments, and as a transfer instrument calibrated against existing absorbed dose standards in conventional reference conditions. The geometry, materials and mode of operation have been chosen to minimize detector perturbations when used in a water phantom, to give a reasonably isotropic response and to minimize the effects of heat transfer when the calorimeter is used in non-reference conditions in a water phantom. The size of the core is meant to meet the needs of measurement in IMRT treatments and is comparable to the size of the air cavity in a type NE2611 ionization chamber. The calorimeter may also be used for small field dosimetry. Initial measurements in reference conditions and in an IMRT head and neck plan, collapsed to gantry angle zero, have been made to estimate the thermal characteristics of the device, and to assess its performance in use. The standard deviation (estimated repeatability) of the reference absorbed dose measurements was 0.02 Gy (0.6%).

Duane, S.; Aldehaybes, M.; Bailey, M.; Lee, N. D.; Thomas, C. G.; Palmans, H.

2012-10-01

328

Cold Storage of Cultural Artifacts  

Microsoft Academic Search

Cold storage will not harm materials as long as the cooling and warming is done in a controlled manner, with the moisture content of the components held stable inside a sealed container. Moisture content is an intrinsic property that is influenced by the humidity in the surrounding air, and secondarily, by temperature. In a sealed container, moisture content will not

329

Hot, Cold, Fresh and Salty  

NSDL National Science Digital Library

In this activity, learners observe the effects of the layering of warm and cold water and water that is more or less saline than regular water. They will discover how the effects of salinity and temperature are the root cause of thermohaline layering in the ocean.

Roth, Jerry; Service, Noaa O.

330

The Cold Blooded Killer: Hypothermia.  

ERIC Educational Resources Information Center

Part of a series of home literacy readers with conversational text and sketches, this booklet depicts the subarctic Alaskan environment where cold makes extreme demands on body metabolism. Body temperature must be maintained above 80F (26.7C). A condition of too little body-heat is termed hypo- ('deficit') thermia ('heat'). Hypothermia is the…

Keller, Rosanne

331

The status of `cold fusion'  

Microsoft Academic Search

The questions raised by reports of nuclear reactions at low energies, so called `cold fusion', are not yet answered to the satisfaction of many scientists. Further experimental investigations of these and related questions seems desirable, at least for scientific if not practical reasons. Properly conducted, such investigations would be indistinguishable from normal research. They would yield information germane to accepted

David J. Nagel

1998-01-01

332

Cold War Geopolitics: Embassy Locations.  

ERIC Educational Resources Information Center

Asserts that the geopolitics of the Cold War can be illustrated by the diplomatic ties among countries, particularly the superpowers and their respective allies. Describes a classroom project in which global patterns of embassy locations are examined and compared. Includes five maps and a chart indicating types of embassy locations. (CFR)

Vogeler, Ingolf

1995-01-01

333

Bad cold for a butterfly?  

Microsoft Academic Search

The tropical butterfly Bicyclus anynana can, in the dry season, encounter temperatures below 10°C or even lower at higher altitudes. We studied the cold resistance of several stages in the life cycle of this butterfly (egg, pupa, adult). Egg hatching declined at low temperatures, with no hatching at +6°C and reduced hatching at 12°C. Pupa could sustain almost two days

Wilte G. Zijlstra; Bas J. Zwaan; Paul M. Brakefield

334

Medical problems from cold exposure  

Microsoft Academic Search

Problems resulting from cold exposure can be successfully treated when a coordinated emergency medical transport system and appropriate equipment are available, as well as medical personnel knowledgeable in the management of frostbite and hypothermia. Clinical suspicion of these disorders is essential. Profoundly hypothermic individuals with no recordable vital signs have been resuscitated after controlled, rapid rewarming measures and the use

Dembert

1982-01-01

335

21 CFR 886.3300 - Absorbable implant (scleral buckling method).  

Code of Federal Regulations, 2010 CFR

...Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a device intended to be implanted on the sclera to aid retinal reattachment. (b) Classification. Class...

2009-04-01

336

A seasonally adjusted concentrator with modifications of absorber shape  

NASA Astrophysics Data System (ADS)

A design procedure for a solar collector absorber is described, which avoids the optical losses which occur through the air gap. A comparison of the performance results of this modified absorber with those of a plane tubular absorber shows an improvement in the intercept factor from 0.8 to 0.92. The surface area of the modified absorber is about 9% larger than the surface of the plane tubular absorber, but the shape is such that the overall heat loss factor is much lower: the total heat loss for the modified absorber at 100 C above ambient is only 0.2% higher than that of the plane tubular one. Performance curves of both absorbers are given, demonstrating the improved efficiency of the modified absorber.

Mullick, S. C.; Nanda, S. K.

1981-12-01

337

Modeling the Effect of Polychromatic Light in Quantitative Absorbance Spectroscopy  

ERIC Educational Resources Information Center

Laboratory experiment is conducted to give the students practical experience with the principles of electronic absorbance spectroscopy. This straightforward approach creates a powerful tool for exploring many of the aspects of quantitative absorbance spectroscopy.

Smith, Rachel; Cantrell, Kevin

2007-01-01

338

21 CFR 878.4490 - Absorbable hemostatic agent and dressing.  

Code of Federal Regulations, 2010 CFR

...agent and dressing. (a) Identification. An absorbable hemostatic agent or dressing is a device intended to produce hemostasis by accelerating the clotting process of blood. It is absorbable. (b) Classification. Class III. (c) Date...

2009-04-01

339

21 CFR 878.4490 - Absorbable hemostatic agent and dressing.  

Code of Federal Regulations, 2010 CFR

...agent and dressing. (a) Identification. An absorbable hemostatic agent or dressing is a device intended to produce hemostasis by accelerating the clotting process of blood. It is absorbable. (b) Classification. Class III. (c) Date...

2010-04-01

340

Experiment research on MM wavelength radar absorbing materials  

Microsoft Academic Search

Experiments to obtain high quality millimeter wavelengths radar absorbing materials are discussed. In order to obtain the best mixing proportion of materials, a great number of materials had been investigated. Several absorbing coating materials achieving this aim are found

Chen ZhiPing; Zhu Qi; Xu Shan-Jia

1999-01-01

341

Irradiation performances of the Superphenix type absorber element.  

National Technical Information Service (NTIS)

Several aspects of irradiation behaviour of the SUPERPHENIX type absorber element are presented in this paper. A large programme of irradiation tests was performed in PHENIX to assess and to improve the absorber pin design whose main characteristics for t...

B. Kryger D. Gosset J. M. Escleine

1995-01-01

342

Optimal Active Vibration Absorber: Design and Experimental Results.  

National Technical Information Service (NTIS)

An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppre...

G. Lee-glauser J. Juang J. L. Sulla

1992-01-01

343

Note on thermal analysis for an inclined plate crotch absorber.  

National Technical Information Service (NTIS)

Crotch absorbers are used to absorb unwanted synchrotron radiation to prevent most of the photons from striking the wall of a vacuum chamber. Since synchrotron radiation generated by bending the positron beam is very powerful, concentrated and penetrating...

M. Choi

1989-01-01

344

Tips to Protect Workers in Cold Environments  

MedlinePLUS

... Anti-Retaliation Tips To Protect Workers In Cold Environments Prolonged exposure to freezing or cold temperatures may ... Tips include: How to Protect Workers Recognize the environmental and workplace conditions that may be dangerous. Learn ...

345

Cold-Weather Sports and Your Family  

MedlinePLUS

... the weather turns frosty. Beating the Cold-Weather Blahs Once a chill is in the air, our ... more sedentary can lead to the "cold-weather blahs." Kids might feel more tired, lethargic, or even ...

346

Helium Find Thaws the Cold Fusion Trail.  

ERIC Educational Resources Information Center

Reported is a study of cold fusion in which trace amounts of helium, possible evidence of an actual fusion reaction, were found. Research methodology is detailed. The controversy over the validity of experimental results with cold fusion are reviewed. (CW)

Pennisi, E.

1991-01-01

347

Tuberculous cold abscess simulating pancreatic pseudocyst.  

PubMed

A patient with a peripancreatic lymph node tuberculosis mimicking pancreatic pseudocyst is reported, which was diagnosed on exploration to be a tuberculous cold abscess. The patient responded to antituberculous drugs after drainage of the cold abscess. PMID:10855077

Karia, K; Mathur, S K

2000-01-01

348

Heat Transfer Measurements in Cold Wind Tunnels.  

National Technical Information Service (NTIS)

Investigations were performed on instrumentation concepts for the purpose of acquiring heat transfer and recovery temperature measurements on models to be tested in cold wind tunnels. The problem in cold wind tunnels is the recovery and model initial (or ...

H. L. Moody K. Jechel

1982-01-01

349

Inorganic UV absorbers for the photostabilisation of wood-clearcoating systems: Comparison with organic UV absorbers  

NASA Astrophysics Data System (ADS)

Inorganic UV absorbers which are widely used today were originally designed neither as a UV blocker in coatings applications, nor for wood protection. In recent years however, there has been extensive interest in these compounds, especially with regard to their properties as a UV blocker in coating applications. In this work, we carried out a comparative study to look into some inorganic and organic UV absorbers used in wood coating applications. The aim of this study is to determine the photostabilisation performances of each type of UV absorbers, to seek possible synergies and the influences of different wood species. We have also searched to find eventual correlation between these performances and the influence of UV absorbers on the film properties. Our study has compared the performances of the following UV absorbers: hombitec RM 300, hombitec RM 400 from the Sachtleben Company; transparent yellow and red iron oxides from Sayerlack as inorganic UV absorbers; organic UV absorbers Tinuvin 1130 and Tinuvin 5151 from Ciba Company. The study was carried out on three wood species: Abies grandis, tauari and European oak. The environmental constraints (in particular the limitation of the emission of volatile organic compounds VOCs) directed our choice towards aqueous formulations marketed by the Sayerlack Arch Coatings Company. The results obtained after 800 h of dry ageing showed that the Tinuvins and the hombitecs present better wood photostabilisations. On the other hand in wet ageing, with the hombitec, there are appearances of some cracks and an increase in the roughness of the surface. This phenomenon is absent when the Tinuvins are used. With regard to these results, the thermomechanical analyses relating to the follow-up of the change of the glass transition temperature ( Tg) of the various coating systems, show a different behaviour between the two types of absorbers. However, contrary to organic UV absorbers, inorganic ones tend to increase Tg during ageing, and, consequently decrease the flexibility of films. These phenomena can lead to the appearance of cracks found in the case of the wet weathering.

Aloui, F.; Ahajji, A.; Irmouli, Y.; George, B.; Charrier, B.; Merlin, A.

2007-02-01

350

Dynamic testing of airplane shock-absorbing struts  

NASA Technical Reports Server (NTRS)

Measurement of perpendicular impacts of a landing gear with different shock-absorbing struts against the drum testing stand. Tests were made with pneumatic shock absorbers having various degrees of damping, liquid shock absorbers, steel-spring shock absorbers and rigid struts. Falling tests and rolling tests. Maximum impact and gradual reduction of the impacts in number and time in the falling tests. Maximum impact and number of weaker impacts in rolling tests.

Langer, P; Thome, W

1932-01-01

351

Cold moderators for pulsed neutron sources  

SciTech Connect

This paper reviews cold moderators in pulsed neutron sources and provides details of the performance of different cold moderator materials and configurations. Analytical forms are presented which describe wavelength spectra and emission time distributions. Several types of cooling arrangements used in pulsed source moderators are described. Choices of materials are surveyed. The author examines some of the radiation damage effects in cold moderators, including the phenomenon of burping'' in irradiated cold solid methane. 9 refs., 15 figs., 4 tabs.

Carpenter, J.M.

1990-01-01

352

The cold equation of state of tantalum  

SciTech Connect

In high-pressure isentropic compression experiments (ICE), the pressure is dominated by the cold curve. In order to obtain an accurate semi-empirical cold curve for Ta, we calculate the thermal pressure from ab initio phonon and electronic excitation spectra. The cold curve is then inferred from ultrasonic and shock data. Our empirical cold pressure is compared to density functional calculations and found to be closer to GGA results at low pressure and to approach LDA at high pressure.

Greeff, Carl W [Los Alamos National Laboratory; Rudin, Sven P [Los Alamos National Laboratory; Corckett, Scott D [Los Alamos National Laboratory; Wills, John M [Los Alamos National Laboratory

2009-01-01

353

Genetic control of plant resistance to cold  

Microsoft Academic Search

Data on the main pathways of the effect of cold on plants and on the pathways of plant responses to cold stress are reviewed.\\u000a Genes involved in these processes are described. Special attention is given to transcription factors regulating expression\\u000a of cold resistance genes. In addition, the participation of hormones and metabolites in the protection of plants from cold-induced\\u000a damage

A. S. Kurbidaeva; M. G. Novokreshchenova

2011-01-01

354

Modified Berenger PML absorbing boundary condition for FDTD meshes  

Microsoft Academic Search

A new modified, perfectly matched layer absorbing boundary condition (MPML ABC) is presented. In the MPML, the introducing of extra degrees of freedom provides the possibility of adjusting the parameters of nonphysical material absorber (PML) for the purpose of enhancing the attenuation rate of the evanescent modes. Compared to Berenger PML, the MPML is more efficient in absorbing the evanescent

B. Chen; D. G. Fang; B. H. Zhou

1995-01-01

355

Bellows joint absorbs torsional deflections in duct system  

NASA Technical Reports Server (NTRS)

Long, thin-walled bellows compressed into a short length absorbs the same amount of torsional deflection as the same tube in full length condition and saves in cost, complexity and space. This bellows has lower torsional spring rate to absorb the bulk of the duct assembly tortional deflections, leaving the other bellows free to absorb axial and angular deflections.

Daniels, C. M.

1966-01-01

356

Phenolic laminate solar absorber panel and method of making  

Microsoft Academic Search

A solar flat plate absorber panel is molded from a laminate consisting of a suitable web material impregnated with a thermosetting phenolic resin. The absorber plate is pressure formed from superimposed layers of material and mold-cured to produce a unitary structure having a first or solar radiation absorbing surface on one side and an integral closed hollow lattice work of

Severson

1979-01-01

357

Electrical tree initiation in polyethylene absorbing Penning gas  

Microsoft Academic Search

AC tree initiation voltage was examined in untreated LDPE, vacuum degassed LDPE and LDPE absorbing He gas (He gas was absorbed after vacuum degassing). The authors have already reported that vacuum degassed LDPE shows much higher tree initiation voltage than untreated LDPE because of the absence of oxygen. Therefore they expected that LDPE absorbing He would show the same property

N. Shimizu; N. Tohyama; H. Sato

1996-01-01

358

14 CFR 27.475 - Tires and shock absorbers.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Tires and shock absorbers. 27.475 Section 27.475...Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed...their static position and the shock absorbers to be in their most critical...

2009-01-01

359

14 CFR 29.475 - Tires and shock absorbers.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Tires and shock absorbers. 29.475 Section 29.475...Loads § 29.475 Tires and shock absorbers. Unless otherwise prescribed...their static position and the shock absorbers to be in their most critical...

2009-01-01

360

14 CFR 29.475 - Tires and shock absorbers.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Tires and shock absorbers. 29.475 Section 29.475...Loads § 29.475 Tires and shock absorbers. Unless otherwise prescribed...their static position and the shock absorbers to be in their most critical...

2010-01-01

361

14 CFR 27.475 - Tires and shock absorbers.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Tires and shock absorbers. 27.475 Section 27.475...Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed...their static position and the shock absorbers to be in their most critical...

2010-01-01

362

Cold Room and Mold Fact Sheet  

Cancer.gov

Biosafety Technical Bulletin:  Cold Rooms and Mold  Low temperatures and limited air movement present ideal conditions for condensation and  moisture build?up, which presents an ideal environment for mold growth in cold rooms.   Improper work practices can quickly lead to surface contamination within a cold room.  

363

Psychrophilic enzymes: hot topics in cold adaptation  

Microsoft Academic Search

More than three-quarters of the Earth's surface is occupied by cold ecosystems, including the ocean depths, and polar and alpine regions. These permanently cold environments have been successfully colonized by a class of extremophilic microorganisms that are known as psychrophiles (which literally means cold-loving). The ability to thrive at temperatures that are close to, or below, the freezing point of

Charles Gerday; Georges Feller

2003-01-01

364

Vitamin C and the common cold  

Microsoft Academic Search

The effect of vitamin C on the common cold has been the subject of several studies. These studies do not support a considerable decrease in the incidence of the common cold with supplemental vitamin C. However, vitamin C has consistently decreased the duration of cold episodes and the severity of symptoms. The benefits that have been observed in different studies

Harri Hemilä

1992-01-01

365

ASCORBIC ACID FUNCTION AND METABOLISM DURING COLDS  

Microsoft Academic Search

Investigations of the relationship between symptoms of the natural common cold and administration of supplementary vitamin C must record and take into account the following factors: 1. Definition of the cold syndrome in terms of incidence (number of colds per person in unit time, generally taken as duration of study); duration of syndrome (number of days during which a defined

C. W. M. Wilson

1975-01-01

366

Human Thermoregulatory Responses to Cold Air Are Altered By Repeated Cold Water Immersion.  

National Technical Information Service (NTIS)

The effects of repeated cold water immersion on thermoregulatory responses to cold air were studied in seven males. A cold air stress test (CAST) was performed before and after completion of an acclimation program consisting of daily 90-min cold (18 C) wa...

A. J. Young S. R. Muza M. N. Sawka R. R. Gonzalez K. B. Pandolf

1986-01-01

367

Human Thermoregulatory Responses to Cold Air are Altered by Repeated Cold Water Immersion.  

National Technical Information Service (NTIS)

The effects of repeated cold water immersion on thermoregulatory responses to cold air were studied in seven males. A cold air stress test (CAST) was performed before and after completion of an acclimation program consisting of daily 90-min cold (18 C) wa...

A. J. Young S. R. Muza M. N. Sawka R. R. Gonzalez K. B. Pandolf

1985-01-01

368

Flexor Tenorrhaphy Using Absorbable Suture Materials  

PubMed Central

Background Nonabsorbable sutures are favorable for repairing flexor tendons. However, absorbable sutures have performed favorably in an animal model. Methods Two-strand sutures using the interlocking modified Kessler method with polydioxanone absorbable sutures 4-0 were used to repair completely ruptured flexor tendons in 55 fingers from 41 consecutive patients. The medical records of average 42 follow up weeks were analyzed retrospectively. The data analyzed using the chi-squared test, and Fisher's exact test was used for postoperative complications. The results were compared with those of other studies. Results Among the index, middle, ring, and little fingers were injured in 9, 17, 16, and 13 fingers, respectively. The injury levels varied from zone 1 to 5. Of the 55 digits in our study, there were 26 (47%) isolated flexor digitorum profundus (FDP) injuries and 29 (53%) combined FDP and with flexor digitorum superficialis injuries. Pulley repair was also conducted. Concomitant injuries of blood vessels and nerves were found in 17 patients (23 fingers); nerve injuries occurred in 5 patients (10 fingers). Two patients had ruptures (3.6%), and one patient had two adhesions (3.6%). Using the original Strickland criteria, all the patients were assessed to be excellent or good. Also, fibrosis and long-term foreign body tissue reactions such as stitch granuloma were less likely occurred in our study. Compared to the Cullen's report that used nonabsorbable sutures, there was no significant difference in the rupture or adhesion rates. Conclusions Therefore, this study suggests that appropriate absorbable core sutures can be used safely for flexor tendon repairs.

Kang, Hyung Joo; Kim, Jin Soo; Ki, Sae Hwi; Roh, Si Young; Yang, Jae Won

2012-01-01

369

[Performance of desulfurizing absorbent of roasted navajoite].  

PubMed

An innovative flue gas desulfurization (FGD) coupling process was proposed in this study to overcome the problems in wet-type limestone/lime processes which include fouling, clogging, and difficulty of selling the by-products and the problems in traditional process for vanadium extraction from navajoite ore such as excessive consumption of sulfuric acid and emissions of pollutants. The performance of a jet bubbling reactor (JBR) at pilot-scale was evaluated using navajoite ore produced in the process of extracting vanadium pentoxide as desulfurization absorbent. Results showed that navajoite ore slurry achieved better desulfurization performance than limestone slurry. When the inlet flue gas pressure drop was 3.0 kPa, the gas flow was about 2350 m3 x h(-1) and the pH of the navajoite ore slurry was higher than 4.5, the desulfurization efficiency was stable about 90%. The SO2 removal efficiency appeared to increase along with the increasing of absorbent cycle-index. The efficiency of the second circulation was improved 3.5% compared to the first circulation. After an operating duration of 40 minutes, the leaching rate of vanadium pentoxide was about 20%, and reached 60% when the by-products were leached with 5% dilute sulfuric acid for 10 hours. The by-product from this process not only could be used to produce vanadium pentoxide which is a valuable industrial product, but also could significantly overcome the pollution problem existing in the traditional refining process of vanadium pentoxide when navajoite ore is used as the feed material. This FGD process using roasted navajoite slurry as absorbent is environmental sound and cost-effective, and shows the potential for application in the field of flue gas desulfurization as well as hydrometallurgy. PMID:20527168

Chen, Fang; Yang, Chun-ping; Gan, Hai-ming; Wu, Ting; Chen, Hai-lin; Chen, Hong; Xu, Ke-hui; Xie, Geng-xin

2010-04-01

370

Evaluation of Absorbing Characteristics and Thermal Contact Resistance of Electromagnetic Wave Absorbing Composite Rubber  

NASA Astrophysics Data System (ADS)

Absorbing characteristics and the thermal contact resistance between the stainless steel plate and the net through the electromagnetic wave absorbing composite rubber sheets were evaluated. The optimum absorbing frequency and the thermal contact resistance decreased by using rubber filled with much amount of thermally conductive magnetic spherical metal fillers. However, the maximum value of the decreasing rate of thermal contact resistance existed because higher content of fillers in the rubber sheet led to the larger hardness. Moreover, the maximum value shifted for higher content of fillers due to the decrease in the hole size of the stainless steel net. Therefore, it was found that the balance of thermal conductivity and hardness of the composite rubber was important and the optimum balance could be evaluated by the present method.

Yoshida, Takahiko; Agari, Yasuyuki; Yoshikado, Shinzo

371

Absorbing boundary conditions for exterior problems  

NASA Technical Reports Server (NTRS)

Elliptic and hyperbolic problems in unbounded regions are considered. These problems, when one wants to solve them numerically, have the difficulty of prescribing boundary conditions at infinity. Computationally, one needs a finite region in which to solve these problems. The corresponding conditions at infinity imposed on the finite distance boundaries should dictate the boundary condition at infinity and be accurate with respect to the interior numerical scheme. Such boundary conditions are commonly referred to as absorbing boundary conditions. A treatment is given of these boundary conditions for wave-like equations.

Hariharan, S. I.

1985-01-01

372

Acoustical model of a Shoddy fibre absorber  

NASA Astrophysics Data System (ADS)

Shoddy fibres or "Shoddies" are a mixture of post-consumer and post-industrial fibres diverted from textile waste streams and recycled into their raw fibre form. They have found widespread use as a raw material for manufacturing sound absorbers that include, but are not limited to: automotive, architectural and home appliance applications. The purpose of this project is to develop a simple acoustic model to describe the acoustic behaviour of sound absorbers composed primarily of Shoddy fibres. The model requires knowledge of the material's bulk density only. To date, these materials have not been the focus of much published research and acoustical designers must rely on models that were developed for other materials or are overly complex. For modelling purposes, an equivalent fluid approach is chosen to balance complexity and accuracy. In deriving the proposed model, several popular equivalent fluid models are selected and the required input parameters for each model identified. The models are: the model of Delaney and Bazley, two models by Miki, the model of Johnson in conjunction with the model of Champoux and Allard and the model of Johnson in conjunction with the model of Lafarge. Characterization testing is carried out on sets of Shoddy absorbers produced using three different manufacturing methods. The measured properties are open porosity, tortuosity, airflow resistivity, the viscous and thermal characteristic lengths and the static thermal permeability. Empirical relationships between model parameters and bulk density are then derived and used to populate the selected models. This yields several 'simplified' models with bulk density as the only parameter. The most accurate model is then selected by comparing each model's prediction to the results of normal incidence sound absorption tests. The model of Johnson-Lafarge populated with the empirical relations is the most accurate model over the range of frequencies considered (approx. 300 Hz - 4000 Hz) Characterization testing yields specific values for intrinsic material parameters that allow for comparison to other porous materials. Individual parameter relations allow users to substitute measured or theoretical values as needed. A new empirical acoustical model is proposed to describe the behaviour of Shoddy-based fibre absorbers. The model requires knowledge of the bulk density only. This parameter is easily measured making application of the model elementary. Mots-clés : Shoddy, porous, fibre, recycled, absorption, model, acoustic.

Manning, John Peter

373

An electromechanical low frequency panel sound absorber.  

PubMed

The sound absorbing properties of a thin micro-perforated plate (MPP) coated with piezoelectric material with shunt damping technology is investigated. First a theoretical model is presented to predict the sound absorption coefficients of a thin plate attached with a piezoelectric patch and electrical circuits. Then the model is extended to analyze the sound absorption for a thin plate with micro perforations and piezoelectric material. Measurements are also carried out in an impedance tube and found to be in good agreements with the theoretical model. The sound absorption of the constructions can be much improved by tuning the electrical circuits. PMID:20707433

Chang, Daoqing; Liu, Bilong; Li, Xiaodong

2010-08-01

374

Ply-tear webbing energy absorber  

NASA Technical Reports Server (NTRS)

Ply-tear webbing is essentially two plain webbings that are bound together by a portion of the warps and that can be torn apart and do work by breaking the binders. Nylon webbing were woven to range in tear force from 1 to 10 kilonewtons. This force is substantially independent of speed, which was as high as 100 m/sec in some cases. A specific energy absorption of 90 J/g was achieved in the dry state. However, lower rated webbings that absorb approximately 40 J/g are recommended for use in practice where it is acceptable.

Stevens, G. W. H.

1972-01-01

375

Piston-rotaxanes as molecular shock absorbers.  

PubMed

We describe the thermomechanical response of a new molecular system that behaves as a shock absorber. The system consists of a rodlike rotaxane connected to a piston and tethered to a surface. The response of this system is dominated by the translational entropy of the rotaxane rings and can be calculated exactly. The force laws are contrasted with those for a rigid rod and a polymer. In some cases, the rotaxanes undergo a sudden transition to a tilted state when compressed. These piston-rotaxanes provide a potential motif for the design of a new class of materials with a novel thermomechanical response. PMID:20158174

Sevick, E M; Williams, D R M

2010-04-20

376

Nonnatural vibrations of hydraulic shock-absorbers  

NASA Astrophysics Data System (ADS)

Based on the procedure developed by the present authors, calculation of a construction unit intended for reducing high levels of vibrations has been carried out. The corresponding physical characteristics of the unit elements have been selected. For a multi-element model, an equivalent of a change-over to a single-mass vibrational system has been found. A criterion for selecting the physical and geometric parameters of vibroshock-absorbers in the form of an inequality between the coefficients given has been obtained.

Dokukova, N. A.; Konon, P. N.; Kaftaikina, E. N.

2008-11-01

377

Two-Photon Cooperative Absorption in Colliding Cold Na Atoms  

NASA Astrophysics Data System (ADS)

Two-photon cooperative absorption is common in solid-state physics. In a sample of trapped cold atoms, this effect may open up new possibilities for the study of nonlinear effects. The experiment described herein starts with two colliding Na atoms in the S hyperfine ground state. The pair absorb two photons, resulting in both a P1/2 and a P3/2 atom. This excitation is observed by ionization using an external light source. A simple model that considers only dipole-dipole interactions between the atoms allows us to understand the basic features observed in the experimental results. Both the pair of generated atoms and the photons originating from their decay are correlated and may have interesting applications that remain to be explored.

Pedrozo-Peñafiel, E.; Paiva, R. R.; Vivanco, F. J.; Bagnato, V. S.; Farias, K. M.

2012-06-01

378

Ultra-cold molecule production.  

SciTech Connect

The production of Ultra-cold molecules is a goal of many laboratories through out the world. Here we are pursuing a unique technique that utilizes the kinematics of atomic and molecular collisions to achieve the goal of producing substantial numbers of sub Kelvin molecules confined in a trap. Here a trap is defined as an apparatus that spatially localizes, in a known location in the laboratory, a sample of molecules whose temperature is below one degree absolute Kelvin. Further, the storage time for the molecules must be sufficient to measure and possibly further cool the molecules. We utilize a technique unique to Sandia to form cold molecules from near mass degenerate collisions between atoms and molecules. This report describes the progress we have made using this novel technique and the further progress towards trapping molecules we have cooled.

Ramirez-Serrano, Jamie; Chandler, David W.; Strecker, Kevin; Rahn, Larry A.

2005-12-01

379

Cold dark matter heats up.  

PubMed

A principal discovery in modern cosmology is that standard model particles comprise only 5 per cent of the mass-energy budget of the Universe. In the ?CDM paradigm, the remaining 95 per cent consists of dark energy (?) and cold dark matter. ?CDM is being challenged by its apparent inability to explain the low-density 'cores' of dark matter measured at the centre of galaxies, where centrally concentrated high-density 'cusps' were predicted. But before drawing conclusions, it is necessary to include the effect of gas and stars, historically seen as passive components of galaxies. We now understand that these can inject heat energy into the cold dark matter through a coupling based on rapid gravitational potential fluctuations, explaining the observed low central densities. PMID:24522596

Pontzen, Andrew; Governato, Fabio

2014-02-13

380

Cold bosons in optical lattices  

NASA Astrophysics Data System (ADS)

Basic properties of cold Bose atoms in optical lattices are reviewed. The main principles of correct self-consistent description of arbitrary systems with Bose-Einstein condensate are formulated. Theoretical methods for describing regular periodic lattices are presented. A special attention is paid to the discussion of Bose-atom properties in the frame of the boson Hubbard model. Optical lattices with arbitrary strong disorder, induced by random potentials, are treated. Possible applications of cold atoms in optical lattices are discussed, with an emphasis of their usefulness for quantum information processing and quantum computing. An important feature of the present review article, distinguishing it from other review works, is that theoretical fundamentals here are not just mentioned in brief, but are thoroughly explained. This makes it easy for the reader to follow the principal points without the immediate necessity of resorting to numerous publications in the field.

Yukalov, V. I.

2009-01-01

381

Cold cathode vacuum discharge tube  

DOEpatents

A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

Boettcher, Gordon E. (Albuquerque, NM)

1998-01-01

382

Acclimatization to cold in humans  

NASA Technical Reports Server (NTRS)

This review focuses on the responses and mechanisms of both natural and artificial acclimatization to a cold environment in mammals, with specific reference to human beings. The purpose is to provide basic information for designers of thermal protection systems for astronauts during intra- and extravehicular activities. Hibernation, heat production, heat loss, vascular responses, body insulation, shivering thermogenesis, water immersion, exercise responses, and clinical symptoms and hypothermia in the elderly are discussed.

Kaciuba-Uscilko, Hanna; Greenleaf, John E.

1989-01-01

383

Medical problems from cold exposure  

SciTech Connect

Problems resulting from cold exposure can be successfully treated when a coordinated emergency medical transport system and appropriate equipment are available, as well as medical personnel knowledgeable in the management of frostbite and hypothermia. Clinical suspicion of these disorders is essential. Profoundly hypothermic individuals with no recordable vital signs have been resuscitated after controlled, rapid rewarming measures and the use of emergency life-support systems.

Dembert, M.L.

1982-01-01

384

Possible theories of cold fusion  

Microsoft Academic Search

Summary  We review some of the key facts in the phenomenology of Pd-hydrides usually referred to as «cold fusion». We conclude that\\u000a all theoretical attempts that concentrate only on few-body interactions, both electromagnetic and nuclear, are probably insufficient\\u000a to explain such phenomena. On the other hand we find good indications that theories describing collective, coherent interactions\\u000a among elementary constituents leading tomacroscopic

M. Fleischmann; S. Pons; G. Preparata

1994-01-01

385

Medical problems from cold exposure.  

PubMed

Problems resulting from cold exposure can be successfully treated when a coordinated emergency medical transport system and appropriate equipment are available, as well as medical personnel knowledgeable in the management of frostbite and hypothermia. Clinical suspicion of these disorders is essential. Profoundly hypothermic individuals with no recordable vital signs have been resuscitated after controlled, rapid rewarming measures and the use of emergency life-support systems. PMID:7055030

Dembert, M L

1982-01-01

386

Hot and Cold Ideal Gases  

NSDL National Science Digital Library

The EJS Hot and Cold Ideal Gases model simulates the mixing of hot and cold two-dimensional ideal gases in a square box. This simulation can be used as part of the activity described in "The Statistical Interpretation of Entropy: An Activity" by Todd Timberlake, to be published in The Physics Teacher. In the model, one gas is initially confined to the left side of the box while the other gas is confined to the right side. An animation window shows the motion of the particles in the box, while an optional graph window plots the temperature of each side of the box, which is determined by measuring the average KE of the particles on each side. The initial number of particles and temperature on each side of the square can be changed and a button allows the user to reverse the particle velocities at any time. The user can modify this simulation if EJS is installed locally by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. EJS Hot and Cold Ideal Gases model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_entropy_HotAndColdIdealGases.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional EJS models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or EJS.

Timberlake, Todd

2010-07-01

387

Properties of Propagation of Electromagnetic Wave in a Multilayer Radar-Absorbing Structure With Plasma and Radar-Absorbing Material  

Microsoft Academic Search

A multilayer radar-absorbing structure with plasma- and radar-absorbing material (RAM) is established to investigate the stealth mechanisms of the multilayer absorber. The method of impedance transformation with multiple dielectrics is used to analyze the propagation of electromagnetic (EM) waves in the multilayer structure. The dependences of EM waves attenuation on the parameters of the plasma and RAMs are provided. The

Cheng-Xun Yuan; Zhong-Xiang Zhou; Jingwen W. Zhang; Xiao-Li Xiang; Yue Feng; Hong-Guo Sun

2011-01-01

388

Nanofriction in Cold Ion Traps  

NASA Astrophysics Data System (ADS)

Sliding friction between crystal lattices and the physics of cold ion traps are so far non-overlapping fields. Two sliding lattices may either stick and show static friction or slip with dynamic friction; cold ions are known to form static chains, helices, or clusters, depending on trapping conditions. Based on simulations, we show that much could be learnt about friction by sliding (e.g., via an electric field) the trapped ion chains over a periodic corrugated potential. Unlike infinite chains where, according to theory, the classic Aubry transition to free sliding may take place, static pinning always shows up in trapped chains. Nonetheless we find that a properly defined static friction still vanishes Aubry-like at a symmetric-asymmetric structural transition, ubiquitous for decreasing corrugation in both straight and zig-zag trapped chains. Dynamic friction can also be addressed by ringdown oscillations of the ion trap. Long theorized static and dynamic one dimensional friction phenomena could thus become exquisitely accessible in future cold ion tribology.

Vanossi, Andrea; Benassi, Andrea; Tosatti, Erio

2011-03-01

389

Small Crystals Aid Cold Fusion  

NASA Astrophysics Data System (ADS)

The 1996 world meeting on cold fusion in Hokkaido, Japan (ICCF6) provided strong evidence that the nuclear product of radiationless cold fusion in a lattice is ^4He. Arata and Zhang(Y. Arata and Y-C Zhang, Proc. Japan Acad. 71B), 304 (1995).^,(Y. Arata and Y-C Zhang, Proc. ICCF6, to appear (1997).) at Osaka University observed ^4He in thermal desorption studies of deuterided Pd powder that had produced 5 kWh/g excess heat; non-deuterided powder showed no ^4He. Gozzi et al.(D. Gozzi et al., Proc. ICCF6, to appear (1997).) at the University of Rome observed ^4He correlating with excess heat power over a thousand hour time period in the gas flow from an open-cell D_2O electrolysis cell, using a bundle of 150 0.25-mm Pd wires as the cathode. Arata and Zhang used a "double structure" cathode consisting of a Pd-metal bottle, evacuated and filled with Pd black (0.4 micron powder)^1,2. They have recorded excess heat from 6 out of 6 cathodes. We attribute the cold fusion successes to use of small Pd grains. Deuterons coherently occupying ordered regions in a metal matrix are predicted to produce heat at higher power density with decreasing crystal size(T.A. Chubb and S.R. Chubb, Proc. ICCF6, to appear (1997).).

Chubb, T. A.; Chubb, S. R.

1997-03-01

390

Mars: Always Cold, Sometimes Wet?  

NASA Technical Reports Server (NTRS)

A synthesis of a diverse suite of observations of H2O-related landforms that are possible Mars analogs from terrestrial polar regions (Devon Island in the Arctic; the Dry Valleys of Antarctica) put into question any requirement for extended episode(s) of warm and wet climate in Mars past. Geologically transient episodes of localized H2O cycling, forced by exogenic impacts, enhanced endogenic heat flow, and/or orbit-driven short-term local environmental change under an otherwise cold, low pressure (=10(exp 2) mbar) global climate, may be sufficient to account for the martian surface's exposed record of aqueous activity. A Mars that was only sometimes locally warm and wet while remaining climatically cold throughout its history is consistent with results (difficulties) encountered in modeling efforts attempting to support warm martian climate hypotheses. Possible analogs from terrestrial cold climate regions for the recent gully features on Mars also illustrate how transient localized aqueous activity might, under specific circumstances, also occur on Mars under the present frigid global climatic regime.

Lee, Pascal; McKay, Christoper P.

2003-01-01

391

Cold cathode vacuum gauging system  

DOEpatents

A vacuum gauging system of the cold cathode type is provided for measuring the pressure of a plurality of separate vacuum systems, such as in a gas centrifuge cascade. Each casing is fitted with a gauge tube assembly which communicates with the vacuum system in the centrifuge casing. Each gauge tube contains an anode which may be in the form of a slender rod or wire hoop and a cathode which may be formed by the wall of the gauge tube. The tube is provided with an insulated high voltage connector to the anode which has a terminal for external connection outside the vacuum casing. The tube extends from the casing so that a portable magnet assembly may be inserted about the tube to provide a magnetic field in the area between the anode and cathode necessary for pressure measurements in a cold cathode-type vacuum gauge arrangement. The portable magnetic assembly is provided with a connector which engages the external high voltage terminal for providing power to the anode within in the gauge tube. Measurement is made in the same manner as the prior cold cathode gauges in that the current through the anode to the cathode is measured as an indication of the pressure. By providing the portable magnetic assembly, a considerable savings in cost, installation, and maintenance of vacuum gauges for pressure measurement in a gas centrifuge cascade is realizable.

Denny, Edward C. (Knoxville, TN)

2004-03-09

392

Superheavy nuclei - cold synthesis and structure  

NASA Astrophysics Data System (ADS)

The quantum mechanical fragmentation theory (QMFT), given for the cold synthesis of new and superheavy elements, is reviewed and the use of radioactive nuclear beams (RNB) and targets (RNT) is discussed. The QMFT is a complete theory of cold nuclear phenomena, namely, the cold fission, cold fusion and cluster radioactivity. Also, the structure calculations based on the axially deformed relativistic mean field (DRMF) approach are presented which predict new regions of spherical magicity, namely Z=120 and N=172 or 184, for superheavy nuclei. This result is discussed in the light of recent experiments reporting the cold synthesis of Z=118 element.

Gupta, Raj K.

2001-08-01

393

Corrosion resistant zirconium alloy absorber material  

SciTech Connect

A method is described of making a zirconium alloy absorber material comprising the steps of: providing a zirconium alloy having iron in a range from about 0.2 to about 0.5 wt. %; about 50 to 120 ppm silicon; about 1,000 to 2,000 ppm oxygen; one or more additional alloying metals selected from the group consisting of tin in a range of from a measurable amount up to about 1.4 wt. chromium in a range from about 0.07 to about 0.25 wt. niobium in a range from a measurable amount up to about 0.6 wt. %, and vanadium in a range of from a measurable amount up to about 0.5 wt. %; and a balance of zirconium; and adding erbium in a range of from about 0.05 to 2.0 wt. % selected from the group consisting of a naturally occurring distribution of erbium isotopes, isotopically enriched erbium- 167, and a combination thereof to act as a burnable absorber.

Pati, S.R.; Corsetti, L.V.

1993-08-31

394

Mapping liquid distribution in absorbent incontinence products.  

PubMed

This paper reviews methods available for mapping the distribution of fluid in incontinence pad materials to assist with evaluating existing products and developing new ones, and to provide data for building and validating predictive models. Specifically, the following technologies are considered and their strengths and limitations described: discrete sensors based on conductance, temperature or optical measurements, optical imaging, gravimetric methods, X-ray imaging and magnetic resonance imaging. It is suggested that the ideal method would enable fluid distribution to be mapped in three dimensions with good spatial and time resolution in single materials and composite structures of simple and complex geometries under static and dynamic mechanical loading. It would also allow liquid to be mapped in products when worn by users. It is concluded that, although each existing method meets some of these requirements, and each requirement is met, at least reasonably well, by at least one method, improved techniques are needed. The particular need for methods that can provide some measurement of liquid saturation within absorbent products, both in the laboratory and in real use, is highlighted. In many cases, simple methods used appropriately are sufficient to elicit the important aspects of liquid transport and storage within absorbent products. PMID:12885195

Landeryou, M A; Yerworth, R J; Cottenden, A M

2003-01-01

395

Decontamination of the skin with absorbing materials.  

PubMed

Stimulation of the penetration of topically applied substances into the skin is a topic of intensive dermatological and pharmacological research. Next to intercellular penetration, i.e. a penetration inside the lipid layers around the corneocytes, follicular penetration also represents an efficient penetration pathway. The hair follicles act as a long-term reservoir for topically applied substances. They are surrounded by or contain several important target structures, such as blood capillaries, stem cells and dendritic cells. Therefore, the hair follicles have to be well protected from hazardous substances coming into contact with the skin. The traditional method of decontamination of the skin involves an intensive washing procedure. However, this process represents a massage, which pushes the hazardous substances even deeper into the hair follicles. In the present study, the application of absorbing materials for decontamination of the skin was investigated after the application of a model substance utilizing the tape-stripping procedure. It was found that absorbing materials are better suited than the washing process for decontamination of the skin. PMID:21116121

Lademann, J; Patzelt, A; Schanzer, S; Richter, H; Gross, I; Menting, K H; Frazier, L; Sterry, W; Antoniou, C

2011-01-01

396

Metamaterial perfect absorber based hot electron photodetection.  

PubMed

While the nonradiative decay of surface plasmons was once thought to be only a parasitic process that limits the performance of plasmonic devices, it has recently been shown that it can be harnessed in the form of hot electrons for use in photocatalysis, photovoltaics, and photodetectors. Unfortunately, the quantum efficiency of hot electron devices remains low due to poor electron injection and in some cases low optical absorption. Here, we demonstrate how metamaterial perfect absorbers can be used to achieve near-unity optical absorption using ultrathin plasmonic nanostructures with thicknesses of 15 nm, smaller than the hot electron diffusion length. By integrating the metamaterial with a silicon substrate, we experimentally demonstrate a broadband and omnidirectional hot electron photodetector with a photoresponsivity that is among the highest yet reported. We also show how the spectral bandwidth and polarization-sensitivity can be manipulated through engineering the geometry of the metamaterial unit cell. These perfect absorber photodetectors could open a pathway for enhancing hot electron based photovoltaic, sensing, and photocatalysis systems. PMID:24837991

Li, Wei; Valentine, Jason

2014-06-11

397

Method of designing layered sound absorbing materials  

NASA Astrophysics Data System (ADS)

A widely used model for describing sound propagation in porous materials is the Johnson-Champoux-Allard model. This rigid frame model is based on five geometrical properties of the porous medium: resistivity, porosity, tortuosity, and viscous and thermal characteristic lengths. Using this model and with the knowledge of such properties for different absorbing materials, the design of a multiple layered system can be optimized efficiently and rapidly. The overall impedance of the layered systems can be calculated by the repeated application of single layer impedance equation. The knowledge of the properties of the materials involved in the layered system and their physical meaning, allows to perform by computer a systematic evaluation of potential layer combinations rather than do it experimentally which is time consuming and always not efficient. The final design of layered materials can then be confirmed by suitable measurements. A method of designing the overall acoustic absorption of multiple layered porous materials is presented. Some aspects based on the material properties, for designing a flat layered absorbing system are considered. Good agreement between measured and computed sound absorption coefficients has been obtained for the studied configurations. [Work supported by N.S.E.R.C. Canada, F.C.A.R. Quebec, and Bombardier Aerospace.

Atalla, Youssef; Panneton, Raymond

2002-11-01

398

Wave based optimization of distributed vibration absorbers  

NASA Astrophysics Data System (ADS)

The concept of distributed vibration absorbers or DVAs has been investigated in recent years as a method of vibration control and sound radiation control for large flexible structures. These devices are comprised of a distributed compliant layer with a distributed mass layer. When such a device is placed onto a structure it forms a sandwich panel configuration with a very soft core. With this configuration the main effect of the DVA is to create forces normal to the surface of the structure and can be used at low frequencies to either add damping, where constrain layer damper treatments are not very effective, or to pin the structure over a narrow frequency bandwidth (i.e., large input impedance/vibration absorber approach). This paper analyses the behavior of these devices using a wave based approach and finds an optimal damping level for the control of broadband disturbances in panels. The optimal design is calculated by solving the differential equations for waves propagating in coupled plates. It is shown that the optimal damping calculated using the infinite case acts as a good ``rule of thumb'' for designing DVAs to control the vibration of finite panels. This is bourn out in both numerical simulations and experiments.

Johnson, Marty; Batton, Brad

2005-09-01

399

Multiple-Path-Length Optical Absorbance Cell  

NASA Technical Reports Server (NTRS)

An optical absorbance cell that offers a selection of multiple optical path lengths has been developed as part of a portable spectrometric instrument that measures absorption spectra of small samples of water and that costs less than does a conventional, non-portable laboratory spectrometer. The instrument is intended, more specifically, for use in studying colored dissolved organic matter (CDOM) in seawater, especially in coastal regions. Accurate characterization of CDOM is necessary for building bio-optical mathematical models of seawater. The multiple path lengths of the absorption cell afford a wide range of sensitivity needed for measuring the optical absorbances associated with the wide range of concentrations of CDOM observed in nature. The instrument operates in the wavelength range of 370 to 725 nm. The major subsystems of the instrument (see figure) include a color-balanced light source; the absorption cell; a peristaltic pump; a high-precision, low-noise fiber optic spectrometer; and a laptop or other personal computer. A fiber-optic cable transmits light from the source to the absorption cell. Other optical fibers transmit light from the absorption cell to the spectrometer,

2001-01-01

400

Configurable metamaterial absorber with pseudo wideband spectrum.  

PubMed

Metamaterials attain their behavior due to resonant interactions among their subwavelength components and thus show specific designer features only in a very narrow frequency band. There is no simple way to dynamically increase the operating bandwidth of a narrowband metamaterial, but it may be possible to change its central frequency, shifting the spectral response to a new frequency range. In this paper, we propose and experimentally demonstrate a metamaterial absorber that can shift its central operating frequency by using mechanical means. The shift is achieved by varying the gap between the metamaterial and an auxiliary dielectric slab parallel to its surface. We also show that it is possible to create multiple absorption peaks by adjusting the size and/or shape of the dielectric slab, and to shift them by moving the slab relative to the metamaterial. Specifically, using numerical simulations we design a microwave metamaterial absorber and experimentally demonstrate that its central frequency can be set anywhere in a 1.6 GHz frequency range. The proposed configuration is simple and easy to make, and may be readily extended to THz frequencies. PMID:22418545

Zhu, Weiren; Huang, Yongjun; Rukhlenko, Ivan D; Wen, Guangjun; Premaratne, Malin

2012-03-12

401

Container and method for absorbing and reducing hydrogen concentration  

DOEpatents

A method for absorbing hydrogen from an enclosed environment comprising providing a vessel; providing a hydrogen storage composition in communication with a vessel, the hydrogen storage composition further comprising a matrix defining a pore size which permits the passage of hydrogen gas while blocking the passage of gaseous poisons; placing a material within the vessel, the material evolving hydrogen gas; sealing the vessel; and absorbing the hydrogen gas released into the vessel by the hydrogen storage composition. A container for absorbing evolved hydrogen gas comprising: a vessel having an interior and adapted for receiving materials which release hydrogen gas; a hydrogen absorbing composition in communication with the interior, the composition defining a matrix surrounding a hydrogen absorber, the matrix permitting the passage of hydrogen gas while excluding gaseous poisons; wherein, when the vessel is sealed, hydrogen gas, which is released into the vessel interior, is absorbed by the hydrogen absorbing composition.

Wicks, George G. (Aiken, SC); Lee, Myung W. (North Augusta, SC); Heung, Leung K. (Aiken, SC)

2001-01-01

402

Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint  

SciTech Connect

As we pursue efforts to lower the capital and installation costs of parabolic trough solar collectors, it is essential to maintain high optical performance. While there are many optical tools available to measure the reflector slope errors of parabolic trough solar collectors, there are few tools to measure the absorber alignment. A new method is presented here to measure the absorber alignment in two dimensions to within 0.5 cm. The absorber alignment is measured using a digital camera and four photogrammetric targets. Physical contact with the receiver absorber or glass is not necessary. The alignment of the absorber is measured along its full length so that sagging of the absorber can be quantified with this technique. The resulting absorber alignment measurement provides critical information required to accurately determine the intercept factor of a collector.

Stynes, J. K.; Ihas, B.

2012-04-01

403

Ionic Basis of Cold Receptors Acting as Thermostats  

Microsoft Academic Search

When temperature (T) of skin decreases stepwise, cold fibers evoke transient afferent discharges, inducing cold sensation and heat-gain responses. Hence we have proposed that cold receptors at distal ends of cold fibers are thermostats to regu- late skin T against cold. Here, with patch-clamp techniques, we studied the ionic basis of cold receptors in cultured dorsal root ganglion (DRG) neurons

Makoto Okazawa; Keizo Takao; Aiko Hori; Takuma Shiraki; Kiyoshi Matsumura; Shigeo Kobayashi

2002-01-01

404

Dynamic vibration absorbers for vibration control within a frequency band  

NASA Astrophysics Data System (ADS)

The use of dynamic vibration absorbers to control the vibration of a structure in both narrow and broadbands is discussed in this paper. As a benchmark problem, a plate incorporating multiple vibration absorbers is formulated, leading to an analytical solution when the number of absorbers yields one. Using this analytical solution, control mechanisms of the vibration absorber in different frequency bandwidths are studied; the coupling properties due to the introduction of the absorber into the host structure are analyzed; and the control performance of the absorber in different control bandwidths is examined with respect to its damping and location. It is found that the interaction between the plate and the absorber by means of the reaction force from the absorber plays a dominant role in a narrow band control, while in a relatively broadband control the dissipation by the absorber damping governs the control performance. When control bandwidth further enlarges, the optimal locations of the absorbers are not only affected by the targeted mode, but also by the other plate modes. These locations need to be determined after establishing a trade-off between the targeted mode and other modes involved in the coupling. Finally, numerical findings are assessed based on a simply-supported plate and a fair agreement between the predicted and measured results is obtained.

Yang, Cheng; Li, Deyu; Cheng, Li

2011-04-01

405

Porous Carbon Nanoparticle Networks with Tunable Absorbability  

NASA Astrophysics Data System (ADS)

Porous carbon materials with high specific surface areas and superhydrophobicity have attracted much research interest due to their potential application in the areas of water filtration, water/oil separation, and oil-spill cleanup. Most reported superhydrophobic porous carbon materials are fabricated by complex processes involving the use of catalysts and high temperatures but with low throughput. Here, we present a facile single-step method for fabricating porous carbon nanoparticle (CNP) networks with selective absorbability for water and oils via the glow discharge of hydrocarbon plasma without a catalyst at room temperature. Porous CNP networks were grown by the continuous deposition of CNPs at a relatively high deposition pressure. By varying the fluorine content, the porous CNP networks exhibited tunable repellence against liquids with various degrees of surface tension. These porous CNP networks could be applied for the separation of not only water/oil mixtures but also mixtures of liquids with different surface tension levels.

Dai, Wei; Kim, Seong Jin; Seong, Won-Kyeong; Kim, Sang Hoon; Lee, Kwang-Ryeol; Kim, Ho-Young; Moon, Myoung-Woon

2013-08-01

406

Microcellular ceramic foams for radar absorbing structures  

SciTech Connect

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of this project is to develop a lightweight, semi-structural, radar-absorbing ceramic foam that can be incorporated into aircraft exhaust systems to replace many of the currently used dense ceramic parts and thereby improve the radar cross section. Although the conventional processes for producing ceramic foams have not been able to provide materials that meet the design specifications for high strength at low density, we have developed and demonstrated a novel sol-gel emulsion process for preparing microcellular ceramic foams in which compositional and microstructural control is expected to provide the requisite high-temperature radar-absorption, strength-to-weight ratio, and thermal insulative properties.

Huling, J.; Phillips, D.

1996-09-01

407

Skin interaction with absorbent hygiene products.  

PubMed

Skin problems due to the use of absorbent hygiene products, such as diapers, incontinence pads, and feminine sanitary articles, are mostly due to climate or chafing discomfort. If these conditions are allowed to prevail, these may develop into an irritant contact dermatitis and eventually superficial skin infections. Skin humidity and aging skin are among the most significant predisposing and aggravating factors for dermatitis development. Improved product design features are believed to explain the decline in observed diaper dermatitis among infants. Where adult incontinence-related skin problems are concerned, it is very important to apply a holistic perspective to understand the influences due to the individual's incontinence level and skin condition, as well as the hygiene and skin care measures provided. Individuals with frail, sensitive skin or with skin diseases may preferably have to use high-quality products, equipped with superabsorbent polymers and water vapor-permeable back sheets, to minimize the risk of skin complications. PMID:18280904

Runeman, Bo

2008-01-01

408

Assessment of some shock absorbing insoles.  

PubMed

Due to the increase in prescription of insoles to relieve symptoms due to skeletal shocks at heel strike a pilot study was initiated to look at some materials used for this purpose. Five materials were examined (Plastazote, Spenco, Sorbothane, Poron (PPT) and Viscolas) by two methods. The first method used an accelerometer mounted between the teeth of one of the authors (PR) to record skeletal shock. The second method used a force plate to record the shock produced by dropping a ball-bearing onto the insoles from a standard height. The results showed that Plastazote is poor at absorbing shock with Spenco and Sorbothane being quite good. The best insole materials tested were Poron (PPT) and Viscolas with the latter being marginally superior. No account was taken of degradation of the materials in use except that Plastazote worn for 72 hours was also used in the study, this producing the worst results. PMID:3725565

Pratt, D J; Rees, P H; Rodgers, C

1986-04-01

409

Porous Carbon Nanoparticle Networks with Tunable Absorbability  

PubMed Central

Porous carbon materials with high specific surface areas and superhydrophobicity have attracted much research interest due to their potential application in the areas of water filtration, water/oil separation, and oil-spill cleanup. Most reported superhydrophobic porous carbon materials are fabricated by complex processes involving the use of catalysts and high temperatures but with low throughput. Here, we present a facile single-step method for fabricating porous carbon nanoparticle (CNP) networks with selective absorbability for water and oils via the glow discharge of hydrocarbon plasma without a catalyst at room temperature. Porous CNP networks were grown by the continuous deposition of CNPs at a relatively high deposition pressure. By varying the fluorine content, the porous CNP networks exhibited tunable repellence against liquids with various degrees of surface tension. These porous CNP networks could be applied for the separation of not only water/oil mixtures but also mixtures of liquids with different surface tension levels.

Dai, Wei; Kim, Seong Jin; Seong, Won-Kyeong; Kim, Sang Hoon; Lee, Kwang-Ryeol; Kim, Ho-Young; Moon, Myoung-Woon

2013-01-01

410

Light Absorbing Aerosols in Mexico City  

NASA Astrophysics Data System (ADS)

The direct effects of aerosol radiative forcing has been identified by the IPCC as a major uncertainty in climate modeling. The DOE Megacity Aerosol Experiment-Mexico City (MAX-Mex), as part of the MILAGRO study in March of 2006, was undertaken to reduce these uncertainties by characterization of the optical, chemical, and physical properties of atmospheric aerosols emitted from this megacity environment. Aerosol samples collected during this study using quartz filters were characterized in the uv-visible-infrared by using surface spectroscopic techniques. These included the use of an integrating sphere approach combined with the use of Kubelka-Munk theory to obtain aerosol absorption spectra. In past work black carbon has been assumed to be the only major absorbing species in atmospheric aerosols with an broad band spectral profile that follows a simple inverse wavelength dependence. Recent work has also identified a number of other absorbing species that can also add to the overall aerosol absorption. These include primary organics from biomass and trash burning and secondary organic aerosols including nitrated PAHs and humic-like substances, or HULIS. By using surface diffuse reflection spectroscopy we have also obtained spectra in the infrared that indicate significant IR absorption in the atmospheric window-region. These data will be presented and compared to spectra of model compounds that allow for evaluation of the potential importance of these species in adding strength to the direct radiative forcing of atmospheric aerosols. This work was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64327 as part of the Atmospheric Science Program.

Marley, N. A.; Kelley, K. L.; Kilaparty, P. S.; Gaffney, J. S.

2008-12-01

411

STUDIES ON THE COMMON COLD  

PubMed Central

1. Studies of the cultivation of the virus of common cold in tissue medium, and the capacity of the culture virus to induce infection in human volunteers are reported. 2. Detailed descriptions are given of the methods employed to isolate the virus, preserve and cultivate it, and to test its activity in human volunteers. 3. The virus of common cold can easily be isolated from properly selected patients and cultivated in tissue medium. 4. When kept in the original nasopharyngeal washings, the virus will survive at ice box temperature under anaerobic conditions for at least 13 days. 5. If the nasopharyngeal washings are frozen and dried in vacuo, the virus retains its activity for at least 4 months. 6. The virus of common cold has been proven to multiply in medium containing chick embryo tissue. Such cultures retain their capacity to produce typical infections in human beings for many transfers involving a period of several months. Attempts to cultivate the virus have been successful in seven out of eight instances. 7. Prolonged cultivation of the virus in tissue medium eventually leads to a loss of activity. 8. Strains of virus under cultivation maintain their potency best when transfers are made at 2 and 3 day intervals. 9. After removal from the incubator a culture of virus rapidly becomes inactive whether it be kept under seal in the ice box or frozen and dried in vacuo. 10. The destructive action of the medium can be prevented if the culture is mixed with gum acacia before freezing and drying in vacuo.

Dochez, A. R.; Mills, K. C.; Kneeland, Yale

1936-01-01

412

Cold cathode vacuum discharge tube  

DOEpatents

A cold cathode vacuum discharge tube, and method for making same, are disclosed with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 15 figs.

Boettcher, G.E.

1998-03-10

413

Cold cathode vacuum discharge tube  

DOEpatents

A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by chemical vapor deposition (CVD) or diamond-like carbon (DLC) deposition are disclosed. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 14 figs.

Boettcher, G.E.

1998-04-14

414

Cold gases with anisotropic interactions  

NASA Astrophysics Data System (ADS)

A cold gas of particles with anisotropic interactions of a general form, due to a polarizing field, is studied. Special cases are atoms or molecules with dipole-dipole or quadrupole-quadrupole interactions. It is shown that the angular dependence of an observable on the direction of the polarizing field is largely determined by symmetry. For a gas in a confined quasi-two-dimensional geometry, the effective interaction is calculated in a general form. Some examples of dipole and quadrupole gases are considered. It is concluded that when anisotropic forces are studied in a general manner, one can obtain simpler results and better understanding for some problems.

Pikovski, Alexander

2014-03-01

415

Modeling Hot and Cold Planets  

NSDL National Science Digital Library

These are the student pages for a three part lesson plan in which students investigate a physical model representing a cold and a hot planet. In the second part, the students interact with a computer model that simulates extreme conditions on some planets, and in the third part they will utilize a data source from the internet to determine the average temperature of the earth and specify the characteristics of a sampling necessary to achieve an accurate average. The lesson plan includes an overview, learning objectives, a list of materials, procedure, data analysis, and worksheets. Teachers' notes are also included.

416

Probing cold dense nuclear matter.  

PubMed

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars. PMID:18511658

Subedi, R; Shneor, R; Monaghan, P; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Boeglin, W; Chen, J-P; Choi, Seonho; Cisbani, E; Craver, B; Frullani, S; Garibaldi, F; Gilad, S; Gilman, R; Glamazdin, O; Hansen, J-O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; de Jager, C W; Jans, E; Jiang, X; Kaufman, L J; Kelleher, A; Kolarkar, A; Kumbartzki, G; Lerose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Ron, G; Rosner, G; Saha, A; Sawatzky, B; Shahinyan, A; Sirca, S; Slifer, K; Solvignon, P; Sulkosky, V; Urciuoli, G M; Voutier, E; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Zheng, X-C; Zhu, L

2008-06-13

417

International workshop on cold neutron sources  

SciTech Connect

The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory on March 5--8, 1990. Cosponsored by Los Alamos and Oak Ridge National Laboratories, the meeting was organized as an International Workshop on Cold Neutron Sources and brought together experts in the field of cold-neutron-source design for reactors and spallation sources. Eighty-four people from seven countries attended. Because the meeting was the first of its kind in over forty years, much time was spent acquainting participants with past and planned activities at reactor and spallation facilities worldwide. As a result, the meeting had more of a conference flavor than one of a workshop. The general topics covered at the workshop included: Criteria for cold source design; neutronic predictions and performance; energy deposition and removal; engineering design, fabrication, and operation; material properties; radiation damage; instrumentation; safety; existing cold sources; and future cold sources.

Russell, G.J.; West, C.D. (comps.) (Los Alamos National Lab., NM (United States)) [comps.; Los Alamos National Lab., NM (United States)

1991-08-01

418

TRPA1 Contributes to Cold Hypersensitivity  

PubMed Central

TRPA1 is a non-selective cation channel expressed by nociceptors. While it is widely accepted that TRPA1 serves as a broad irritancy receptor for a variety of reactive chemicals, its role in cold sensation remains controversial. Here, we demonstrate that mild cooling markedly increases agonist-evoked rat TRPA1 currents. In the absence of an agonist, even noxious cold only increases current amplitude slightly. These results suggest that TRPA1 is a key mediator of cold hypersensitivity in pathological conditions where reactive oxygen species and pro-inflammatory activators of the channel are present, but likely plays a comparatively minor role in acute cold sensation. Supporting this, cold hypersensitivity can be induced in wild-type but not Trpa1-/- mice by subcutaneous administration of a TRPA1 agonist. Furthermore, the selective TRPA1 antagonist HC-030031 reduces cold hypersensitivity in rodent models of inflammatory and neuropathic pain.

Camino, Donato del; Murphy, Sarah; Heiry, Melissa; Barrett, Lee B.; Earley, Taryn J.; Cook, Colby A.; Petrus, Matt J.; Zhao, Michael; D'Amours, Marc; Deering, Nate; Brenner, Gary J.; Costigan, Michael; Hayward, Neil J.; Chong, Jayhong A.; Fanger, Christopher M.; Woolf, Clifford J.; Patapoutian, Ardem; Moran, Magdalene M.

2010-01-01

419

Tautochronic centrifugal pendulum vibration absorbers. General design and analysis  

NASA Astrophysics Data System (ADS)

Since the 1930s, centrifugal pendulum vibration absorbers have been used in rotating and reciprocating machinery for the attenuation of torsional vibrations. A large variety of absorber types were suggested and the design was done by linearization theory until the introduction of the tautochronic bifilar pendulum absorbers. Since then, the performance and dynamic stability of this specific absorber type have been considered in analytical and numerical investigations. Different perturbations, e.g. nonlinear mistuning, were considered in order to optimize the system performance, but the characteristic bifilar design remained unchanged. In this paper, a general approach for the design of tautochronic pendulum vibration absorbers is proposed. As a result, it is possible to deal with a large variety of non-bifilar centrifugal vibration absorber designs which provide application-related optimal performance and resolve some of the existing design limitations.

Mayet, J.; Ulbrich, H.

2014-02-01

420

Application of magnetorheological fluid in industrial shock absorbers  

NASA Astrophysics Data System (ADS)

The paper presents investigation results of a semi-active industrial shock absorber with magnetorheological (MR) fluid, which is capable of controlling the stopping process of moving objects, e.g. on transportation lines. The proposed solution makes it possible to adjust the braking force (by electronic controller) to the kinetic energy of the moving object. The paper presents an overview of passive shock absorbers. Next, the design concept of a semi-active shock absorber with the MR fluid is proposed. The theoretical model and the simulation model of the MR absorber and the stopping process are presented. The paper reports investigations of a prototype MR shock absorber used to stop a mass moving on an inclined plane. The braking force of the absorber was changed by an electronic control system according to the current position of the moving mass. Finally, the simulation and investigation results are discussed and compared.

Milecki, Andrzej; Hauke, Miko?aj

2012-04-01

421

Isocurvature cold dark matter fluctuations  

NASA Technical Reports Server (NTRS)

According to Preskill et al. (1983), the axion field represents a particularly attractive candidate for the dark matter in the universe. In many respects it behaves like other forms of cold dark matter, such as massive gravitinos, photinos, and monopoles. It is, however, a pseudo-Goldstone boson of very low mass, and it is only because of rapid coherent oscillations of the field that it can dominate the mass density of the universe. In the present paper it is assumed that the isocurvature mode is dominant. The linear evolution calculations conducted do not depend upon specific details of particle physics. For this reason, the conducted discussion is applicable to any cold dark matter model with isocurvature perturbations. The results of the study lead to the conclusion that scale-invariant isocurvature perturbations do not seem an attractive possibility for the origin of large-scale structure. The findings strengthen the review that primordial adiabatic perturbations were the dominant fluctuations in the early stages of the Big Bang.

Efstathiou, G.; Bond, J. R.

1986-01-01

422

International workshop on cold neutron sources  

Microsoft Academic Search

The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory on March 5 to 8, 1990. Cosponsored by Los Alamos and Oak Ridge National Laboratories, the meeting was organized as an International Workshop on Cold Neutron Sources and brought together experts in the field of cold-neutron-source design for reactors and spallation sources. Eighty-four people

G. J. Russell; C. D. West

1991-01-01

423

Piezoelectric Actuators On A Cold Finger  

NASA Technical Reports Server (NTRS)

Developmental system for active suppression of vibrations of cold finger includes three piezoelectric actuators bonded to outer surface. Actuators used to suppress longitudinal and lateral vibrations of upper end of cold finger by applying opposing vibrations. Cold finger in question is part of a cryogenic system associated with an infrared imaging detector. When fully developed, system would be feedback sensor/control/actuator system automatically adapting to changing vibrational environment and suppresses pressure-induced vibrations by imposing compensatory vibrations via actuators.

Kuo, Chin-Po; Garba, John A.; Glaser, Robert J.

1995-01-01

424

A new absorbing layer boundary condition for the wave equation  

SciTech Connect

A new absorbing boundary condition using an absorbing layer is presented for application to finite-difference time-domain (FDTD) calculation of the wave equation. This algorithm is by construction a hybrid between the Berenger perfectly matched layer (PML) algorithm and the one-way Sommerfeld algorithm. The new prescription contains both of these earlier ones as particular cases, and retains benefits from both. Numerical results indicate that the new algorithm provides absorbing rates superior to those of the PML algorithm.

Vay, J.L.

2000-09-11

425

Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads  

NASA Technical Reports Server (NTRS)

The use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads was discussed. A qualitative description was given of the concept of the dynamic absorbers and some results of analytical studies showing the degree of reduction in vibratory loads attainable are presented. Operational experience of vertical plane dynamic absorbers on the OH-6A helicopter is also discussed.

Amer, K. B.; Neff, J. R.

1974-01-01

426

Effect of finite absorber dimensions on. gamma. -ray attenuation measurements  

SciTech Connect

Using /sup 137/Cs ..gamma.. rays, the effect of finite absorber dimensions on attenuation measurements has been studied. Copper and mercury targets were used. Absorber dimensions up to five mean free paths were used. A correlated effect was observed in the measurements due to absorber thickness and its dimensions in the transverse directions. The values of the attenuation coefficients for copper and mercury have also been determined.

Varier, K.M.; Kunju, S.N.; Madhusudanan, K.

1986-04-01

427

Red Fluorescent Protein with Reversibly Photoswitchable Absorbance for Photochromic FRET  

Microsoft Academic Search

We have developed the first red fluorescent protein, named rsTagRFP, which possesses reversibly photoswitchable absorbance spectra. Illumination with blue and yellow light switches rsTagRFP into a red fluorescent state (ON state) or nonfluorescent state (OFF state), respectively. The ON and OFF states exhibit absorbance maxima at 567 and 440 nm, respectively. Due to the photoswitchable absorbance, rsTagRFP can be used

Fedor V. Subach; Lijuan Zhang; Theodorus W. J. Gadella; Nadya G. Gurskaya; Konstantin A. Lukyanov; Vladislav V. Verkhusha

2010-01-01

428

Selection of new absorbents for carbon dioxide capture  

Microsoft Academic Search

This work focuses on selecting new absorbents for CO2 capture. Absorption of CO2 was studied at 40°C using both single and mixed amine-based absorbents. The experimental results show that most absorbents tested have a poorer performance than MEA, but that aqueous AEEA might be a possible contender. In addition to the absorption measurements, the VLE of CO2 in the selected

Sholeh Ma’mun; Hallvard F. Svendsen; Karl A. Hoff; Olav Juliussen

2007-01-01

429

A simple measuring method of reflectivity for radar absorbing material  

Microsoft Academic Search

The basic principle of measuring reflectivity for radar absorbing material (RAM) is analyzed. And a simple method for measuring reflectivity of radar absorbing material using vector network analyzer HP8722ET and APC-7mm coaxial line is presented. The results indicate that the reflectivity of the radar absorbing material can be measured in 0.05-18 GHz using this method. Under the ordinary laboratory condition,

Feng Yongbao; Qiu Tai; Shen Chunying; Li Xiaoyun

2005-01-01

430

Hybrid BâC absorber control rod evaluation report. [PWR  

Microsoft Academic Search

The report evaluates the planned introduction of a Westinghouse hybrid boron carbide (BâC) full-length rod cluster control assembly (RCCA) into three and four loop 12' 17 x 17 fuel assemblies cores. The hybrid RCCA consists of 24 hybrid absorber rods, each containing silver--indium--cadmium (Ag--In--Cd) absorber and BâC absorber pellets stacked on top of the Ag--In--Cd. Except for the substitution of

Skaritka

1976-01-01

431

Absorbing boundaries in the mean-field approximation  

SciTech Connect

Absorbing boundaries in the mean-field approximation are investigated and applied to small systems interacting with strong laser fields. Two types of calculations are considered: (i) a variational approach with a complex absorbing potential included in the full Hamiltonian and (ii) the inclusion of a complex absorbing potential in the single-particle equations. It is elucidated that the second approach outperforms the variational approach for small grids.

Jhala, Chirag; Dreissigacker, Ingo; Lein, Manfred [Institut fuer Theoretische Physik and Centre for Quantum Engineering and Space-Time Research (QUEST), Leibniz Universitaet Hannover, Appelstrasse 2, D-30167 Hannover (Germany)

2010-12-15

432

Silk / absorbable polyester hybrid medical devices and applications thereof  

US Patent & Trademark Office Database

Silk/absorbable polyester hybrid medical devices for tissue repair and regeneration are formed of degummed, naturally produced, multifilament silk yarn in combination with at least one absorbable polyester in the form of a surface coating, with or without an antimicrobial agent, for producing value-added braided silk sutures and multifilament yarn, as well as silk/absorbable polyester fiber composites, for producing tailored hybrid sutures, meshes, and scaffolds for tissue regeneration.

2013-11-12

433

Graphene metamaterials based tunable terahertz absorber: effective surface conductivity approach.  

PubMed

In this paper we present the efficient design of functional thin-film metamaterial devices with the effective surface conductivity approach. As an example, we demonstrate a graphene based perfect absorber. After formulating the requirements to the perfect absorber in terms of surface conductivity we investigate the properties of graphene wire medium and graphene fishnet metamaterials and demonstrate both narrowband and broadband tunable absorbers. PMID:23572003

Andryieuski, Andrei; Lavrinenko, Andrei V

2013-04-01

434

Evaporative cooling enhanced cold storage system  

DOEpatents

The invention provides an evaporatively enhanced cold storage system wherein a warm air stream is cooled and the cooled air stream is thereafter passed into contact with a cold storage unit. Moisture is added to the cooled air stream prior to or during contact of the cooled air stream with the cold storage unit to effect enhanced cooling of the cold storage unit due to evaporation of all or a portion of the added moisture. Preferably at least a portion of the added moisture comprises water condensed during the cooling of the warm air stream. 3 figures.

Carr, P.

1991-10-15

435

Evaporative cooling enhanced cold storage system  

DOEpatents

The invention provides an evaporatively enhanced cold storage system wherein a warm air stream is cooled and the cooled air stream is thereafter passed into contact with a cold storage unit. Moisture is added to the cooled air stream prior to or during contact of the cooled air stream with the cold storage unit to effect enhanced cooling of the cold storage unit due to evaporation of all or a portion of the added moisture. Preferably at least a portion of the added moisture comprises water condensed during the cooling of the warm air stream.

Carr, Peter (Cary, NC)

1991-01-01

436

Directional self-supporting pyramid shaped hot water solar absorber  

SciTech Connect

A solar absorber to be mounted on the roofs of buildings, the absorber having the form of a pyramid with the heat absorbing elements mounted across the upward extending faces of the pyramid and the base formed to conform to the contour of the roof so that the solar absorber may be fixedly mounted on the roof of a building. In a modified form of my invention each face of the pyramid is independently equipped with a heat sensor which is electrically connected to a water valve and water circulator so that water circulates only through the faces exposed to sunlight.

Tornquist, A.

1980-01-22

437

Decomposition-based recovery of absorbers in turbid media  

SciTech Connect

We suggest that the concept of the point-spread function traditionally used to predict the blurred image pattern of various light sources embedded inside turbid media can be generalized under certain conditions to predict also the presence and location of spatially localized absorbing inhomogeneities based on shadow point-spread functions associated with each localized absorber in the medium. The combined image obtained from several absorbers can then be decomposed approximately into the arithmetic sums of these individual shadow point-spread functions with suitable weights that can be obtained from multiple-regression analysis. This technique permits the reconstruction of the location of absorbers.

Campbell, S. D.; Goodin, I. L.; Grobe, S. D.; Su, Q.; Grobe, R. [Intense Laser Physics Theory Unit and Department of Physics, Illinois State University, Normal, Illinois 61790-4560 (United States)

2007-12-15

438

Optimal active vibration absorber - Design and experimental results  

NASA Technical Reports Server (NTRS)

An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

1993-01-01

439

Optimal active vibration absorber: Design and experimental results  

NASA Technical Reports Server (NTRS)

An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

1992-01-01

440

Cold Regions Science and Engineering Monograph 1-A: Characteristics of the Cold Regions.  

National Technical Information Service (NTIS)

The monograph gives a brief introduction to total cold environments preparatory to the more detailed treatments of the later works in the series 'Cold Regions Science and Engineering.' The author's photographs are particularly effective and a selected bib...

R. W. Gerdel

1969-01-01

441

Transcriptomic analysis of cold response in tomato fruits identifies dehydrin as a marker of cold stress  

Microsoft Academic Search

Tomato is sensitive to cold during vegetative growth, fruit set, development, and ripening. We have characterized the effect\\u000a of cold stress (6°C for up to 48 h) on the transcriptome of Micro-Tom tomato fruits during ripening by subtractive PCR. The\\u000a cold stress caused modifications in gene expression of housekeeping genes. From a total of 38 genes up-regulated by cold,\\u000a only

J. Weiss; M. Egea-Cortines

2009-01-01

442

Imaging in the optical and near-infrared regimes II. Arcsecond spatial resolution of widely distributed cold dust in spiral galaxies  

NASA Astrophysics Data System (ADS)

For extragalactic systems, the InfraRed Astronomical Satellite IRAS only surveyed "warm" dust; in spirals, that dust delineates spiral arms and is associated with OB stars, H II and star forming regions. On the other hand, sub-mm/mm observations of spiral galaxies have brought the issue of cold dust to the fore, but with controversial and diametrically opposed conclusions. The uncertainty in the estimate of the average far- IR to mm flux ratio amounts to one order of magnitude or more. A key problem lies in our current lack of knowledge of the spatial extension of cold dust. We contend that high spatial resolution, ground-based, digital imaging in the optical and near-infrared bands is sensitive to dust grains of all dust temperatures; moreover, the resolution in such dust tracing surveys is one order of magnitude better than that possible with the largest sub-mm/mm telescopes and two orders of magnitude better than with IRAS. We demonstrate that radiative transfer models (involving multiple scattering) combined with B-K' and V-K' colour maps, provide a powerful and independent tool for exploring the widespread distribution of cold interarm dust powered by the general interstellar radiation field of old disk stars. Two galaxies (NGC 4736 and NGC 4826), both detected in the sub-mm, are selected to demonstrate the technique for an embedded dust geometry and that of a foreground screen. We identify widely distributed interarm cirrus dust embedded within the disk of NGC 4736, and we compare extinctions using our technique with extinctions inferred from far-infrared observations secured with the Kuiper Airborne Observatory. For NGC 4826, the most likely dust geometry is that of a distinct, foreground dust screen. The power of the new method's quantitative accuracy is that, by relying on radiative transfer models invoking continuous media, the cold dust masses we infer are lower limits. The transmission coefficient in clumpy, heterogeneous, N-phase scattering ISMs will be even higher. As a lower limit, NGC 4736 and NGC 4826 require an additional 90 per cent in the form of cold dust - a dust component essentially missed by IRAS. An important conclusion from our work is that the Galactic dust-to-gas ratio, rather than being exceptionally high, may again be rather representative - at least for the spiral galaxies studied here.

Block, D. L.; Witt, A. N.; Grosbol, P.; Stockton, A.; Moneti, A.

1994-08-01

443

Multifunctional Space Evaporator-Absorber-Radiator (SEAR)  

NASA Technical Reports Server (NTRS)

A system for non-venting thermal control for spacesuits was built by integrating two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's flexible version of the Lithium Chloride Absorber Radiator (LCAR). This SEAR system was tested in relevant thermal vacuum conditions. These tests show that a 1 sq m radiator having about three times as much absorption media as in the test article would be required to support a 7 hour spacewalk. The serial flow arrangement of the LCAR of the flexible version proved to be inefficient for venting non-condensable gas (NCG). A different LCAR packaging arrangement was conceived wherein the Portable Life Support System (PLSS) housing would be made with a high-strength carbon fiber composite honeycomb, the cells of which would be filled with the chemical absorption media. This new packaging reduce the mass and volume impact of the SEAR on the Portable Life Support System (PLSS) compared to the flexible design. A 0.2 sq m panel with flight-like honeycomb geometry is being constructed and will be tested in thermal and thermal vacuum conditions. Design analyses forecast improved system performance and improved NCG control. A flight-like regeneration system also is also being built and tested. Design analyses for the structurally integrated prototype as well as the earlier test data show that SEAR is not only practical for spacesuits but also has useful applications in spacecraft thermal control.

Bue, Grant C.; Hodgson, Ed; Izenson, Mike; Chen, Weibo

2013-01-01

444

Spacesuit Evaporator-Absorber-Radiator (SEAR)  

NASA Technical Reports Server (NTRS)

For decades advanced spacesuit developers have pursued a regenerable, robust non-venting system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's lithium chloride Heat Pump Radiator (HPR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. The SEAR is evacuated at the onset of operations and thereafter, the water vapor absorption rate of the HPR maintains a low pressure environment for the SWME to evaporate effectively. This water vapor captured by solid LiCl in the HPR with a high enthalpy of absorption, results in sufficient temperature lift to reject most of the heat to space by radiation. After the sortie, the HPR would be heated up in a regenerator to drive off and recover the absorbed evaporant. A one-fourth scale prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The HPR was able to stably reject 60 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

Bue, Grant C.; Hodgson, Ed; Izenso, Mike; Chan, Weibo; Cupples, Scott

2011-01-01

445

On cold spots in tumor subvolumes.  

PubMed

Losses in tumor control are estimated for cold spots of various "sizes" and degrees of "cold dose." This question is important in the context of intensity modulated radiotherapy where differential dose-volume histograms (DVHs) for targets that abut a critical structure often exhibit a cold dose tail. This can be detrimental to tumor control probability (TCP) for fractions of cold volumes even as small as 1%, if the cold dose is lower than the prescribed dose by substantially more than 10%. The Niemierko-Goitein linear-quadratic algorithm with gamma50 slope 1-3 was used to study the effect of cold spots of various degrees (dose deficit below the prescription dose) and size (fractional volume of the cold dose). A two-bin model DVH has been constructed in which the cold dose bin is allowed to vary from a dose deficit of 1%-50% below prescription dose and to have volumes varying from 1% to 90%. In order to study and quantify the effect of a small volume of cold dose on TCP and effective uniform dose (EUD), a four-bin DVH model has been constructed in which the lowest dose bin, which has a fractional volume of 1%, is allowed to vary from 10% to 45% dose deficit below prescription dose. The highest dose bin represents a simultaneous boost. For fixed size of the cold spot the calculated values of TCP decreased rapidly with increasing degrees of cold dose for any size of the cold spot, even as small as 1% fractional volume. For the four-subvolume model, in which the highest dose bin has a fractional volume of 80% and is set at a boost dose of 10% above prescription dose, it is found that the loss in TCP and EUD is moderate as long as the cold 1% subvolume has a deficit less than approximately 20%. However, as the dose deficit in the 1% subvolume bin increases further it drives TCP and EUD rapidly down and can lead to a serious loss in TCP and EUD. Since a dose deficit to a 1% volume of the target that is larger than 20% of the prescription dose may lead to serious loss of TCP, even if 80% of the target receives a 10% boost, particular attention has to be paid to small-volume cold regions in the target. The effect of cold regions on TCP can be minimized if the EUD associated with the target DVH is constrained to be equal to or larger than the prescription dose. PMID:12148742

Tomé, Wolfgang A; Fowler, Jack F

2002-07-01

446

HOM absorbers for ERL cryomodules at BNL  

SciTech Connect

The physics needs and technical requirements for several future accelerator projects at the Relativistic Heavy Ion Collider (RHIC) all involve electron Energy Recovery Linacs (ERL). The required high-current, high-charge operating parameters make effective higher-order-mode (HOM) damping mandatory and the development of HOM dampers for a prototypical five-cell cavity is actively pursued. An experimental five-cell niobium cavity with ferrite dampers has been constructed, and effective HOM damping has been demonstrated at room and superconducting (SC) temperatures. A novel type of ferrite damper around a ceramic break has been developed for the ERL electron gun and prototype tests are also reported. Contemplated future projects are based on assembling a chain of superconducting cavities in a common cryomodule with the dampers placed in the cold space between the cavities, imposing severe longitudinal space constraints. Various damper configurations have been studied by placing them between two five-cell copper cavities. Measured and simulated copper cavity results, external Q-values of possible dampers and fundamental mode losses are presented.

Hahn,H.; Ben-Zvi, I.; Hammons, L.; Xu, W.

2009-09-20

447

Development of cold neutron pulser for delayed choice experiment  

Microsoft Academic Search

The delayed choice experiment was done using the cold neutron spin interferometer of Jamin type arrangement which is installed at the JRR-3M of JAERI. “A multilayer polarizing cold neutron mirror placed in the pulsed magnetic field” is called a multilayer cold neutron pulser, or, in short, a cold neutron pulser. The switching function of the cold neutron pulser was used

Takeshi Kawai; Toru Ebisawa; Seiji Tasaki; Masahiro Hino; Dai Yamazaki; Hiroshi Tahata; Tsunekazu Akiyoshi; Yoko Matsumoto; Norio Achiwa; Yoshie Otake

1997-01-01

448

Development of cold neutron pulser for delayed choice experiment  

Microsoft Academic Search

The delayed choice experiment was done using the cold neutron spin interferometer of Jamin type arrangement which is installed at the JRR-3M of JAERI. ``A multilayer polarizing cold neutron mirror placed in the pulsed magnetic field'' is called a multilayer cold neutron pulser, or, in short, a cold neutron pulser. The switching function of the cold neutron pulser was used

Takeshi Kawai; Toru Ebisawa; Seiji Tasaki; Masahiro Hino; Dai Yamazaki; Hiroshi Tahata; Tsunekazu Akiyoshi; Yoko Matsumoto; Norio Achiwa; Yoshie Otake

1998-01-01

449

Electrodeposition process reduces cost of cold plates  

NASA Technical Reports Server (NTRS)

Efficient nickel heat-exchanger cold plates can be fabricated less expensively than stainless steel plates. If adapted to mass production, it is estimated that nickel cold plates might be made for about 30 percent less than stainless-steel plates.

Ruppe, E. P.

1980-01-01

450

A Cool Channel in Cold Transduction  

NSDL National Science Digital Library

Transient receptor potential melastatin 8 (TRPM8), a calcium-permeable cation channel activated by cold, cooling compounds and voltage, is the main molecular entity responsible for detection of cold temperatures in the somatosensory system. Here, we review the biophysical properties, physiological role, and near-membrane trafficking of this exciting polymodal ion channel.

PhD Ramon Latorre (Universidad de Chile Facultad de Ciencias Departamento de Biologýôa and Centro de Estudios Cientýôficos); Sebastian Brauchi (Universidad Austral de Chile Instituto de Fisiología); Rodolfo Madrid (Universidad de Santiago de Chile Laboratorio de Neurociencia, Departamento de Biología); Patricio Orio (Universidad de Valparaíso Centro Interdisciplinario de Neurociencia de Valparaíso)

2011-08-01

451

Prevention of Cold Injuries During Exercise.  

National Technical Information Service (NTIS)

In is the position of the American College of Sports Medicine that exercise can be performed safely in most cold-weather environments without incurring cold-weather injuries. The key to prevention is use of a comprehensive risk management strategy that: (...

A. J. Young E. Glickman G. G. Giesbrecht J. W. Castellani M. B. Ducharme

2006-01-01

452

Cold spray deposition of thermoplastic powder  

Microsoft Academic Search

The cold spray deposition of polyolefin powder has been investigated, at substantially lower velocities (up to ?135 m s?1) than those used in the cold gas dynamic spray (CGDS) process for metals. The particles were accelerated at room temperature in air through a cylindrical nozzle, and were deposited on to polyethylene and aluminium substrates. Fully-dense deposits were formed at temperatures substantially

Y. Xu; I. M. Hutchings

2006-01-01

453

Heritability of Cold Tolerance in Red Drum  

Microsoft Academic Search

Heritability (h ) of cold tolerance was estimated for red drum Sciaenops ocellatus, an economically important sciaenid fish in the southern USA. Nineteen families were generated via environmentally induced spawning of multiple sets of five broodfish (three dams × two sires) and were mixed in three common-garden replicate tanks for cold tolerance challenge. All offspring were assigned postmortem to parents

Liang Ma; Eric Saillant; Delbert M. Gatlin III; William H. Neill; Robert R. Vega; John R. Gold

2007-01-01

454

The Origins of the Cold War.  

ERIC Educational Resources Information Center

Briefly reviews conventional reasoning about the start of the Cold War. Describes contemporary revisionist views of the Cold War and the reasons they arose. Maintains that American leaders exaggerated the Soviet ideological and military threat, spurring an American arms build-up which ultimately led to the present-day arms race. (JDH)

Paterson, Thomas G.

1986-01-01

455

Cold Stress Responses in Mesophilic Bacteria  

Microsoft Academic Search

The diversity of the prokaryotes that have been studied, combined with the many different effects of low temperature, has led to an extensive literature concerning cold stress responses in mesophilic bacteria. The aim of this review is to discuss the effects of cold on the behavior of bacteria. The following three responses will be described: (i) biochemical modifications consisting first

Jean-Michel Panoff; Bouachanh Thammavongs; Micheline Guéguen; Philippe Boutibonnes

1998-01-01

456

Preserving Alaska's early Cold War legacy  

Microsoft Academic Search

The US Air Force owns and operates numerous facilities that were constructed during the Cold War era. The end of the Cold War prompted many changes in the operation of these properties: missions changed, facilities were modified, and entire bases were closed or realigned. The widespread downsizing of the US military stimulated concern over the potential loss of properties that

J. Hoffecker; M. Whorton

1999-01-01

457

Lessons on the Cold War. Lesson Plan.  

ERIC Educational Resources Information Center

Contends that the end of the Cold War requires teachers to change their teaching methods and content. Presents six lessons, most with three individual student activities, that trace the Cold War from the pre-World War I era through the end of the Vietnam War. (CFR)

Cunningham, Susan J.

1994-01-01

458

Study on a New Type of wide Frequency Absorbing Coating.  

National Technical Information Service (NTIS)

A new type of wave-absorbing composite coating is made by inserting a wave frequency selecting surface into Dallenbach coating. Analysis of the absorbing capability of the coating with virtual circuit and transmission line theory showed that it is far sup...

F. Lin L. C. Shiao

1995-01-01

459

Neutron absorbing room temperature vulcanizable silicone rubber compositions  

Microsoft Academic Search

A neutron absorbing composition comprising a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a boron compound or boron powder as the neutron absorbing ingredient. An especially useful boron

Zoch; Harold L

1979-01-01

460

Performance of an artificial absorber for truncating FEM meshes  

NASA Technical Reports Server (NTRS)

We investigate the effectiveness of an artificial absorber for truncating finite element (FE) meshes. Specifically, we present the implementation of a novel mesh truncation approach using a perfectly matched anisotropic absorber for waveguides and stripline circuits. This truncation scheme is useful in many applications, including antennas, scattering, and microwave circuits.

Gong, Jian; Volakis, John L.

1995-01-01

461

21 CFR 880.5300 - Medical absorbent fiber.  

Code of Federal Regulations, 2010 CFR

...Identification. A medical absorbent fiber is a device intended for medical...is made from cotton or synthetic fiber in the shape of a ball or a pad and that is used for...patient's body surface. Absorbent fibers intended solely for...

2010-04-01

462

21 CFR 880.5300 - Medical absorbent fiber.  

Code of Federal Regulations, 2010 CFR

...Identification. A medical absorbent fiber is a device intended for medical...is made from cotton or synthetic fiber in the shape of a ball or a pad and that is used for...patient's body surface. Absorbent fibers intended solely for...

2009-04-01

463

Preliminary Sizing of Vibration Absorber for Space Mast Structures.  

National Technical Information Service (NTIS)

A simple method of sizing a vibration absorber for a large, cantilevered flexible mast is presented. The method is based on Den Hartog's vibration absorber theory for two-degree-of-freedom systems. Generalized design curves are presented as well as specif...

H. G. Mccomb M. F. Card S. W. Peebles

1982-01-01

464

An Absorbing Look at Terry-Cloth Towels  

ERIC Educational Resources Information Center

This article describes a lesson where students explore the absorbency of several towels with different weaves and weights. The lesson follows the 5E learning-cycle model and incorporates engineering in the sense of product testing with a focus on the relationship between the weave of a towel and its absorbency. The National Science Education…

Moyer, Richard; Everett, Susan

2010-01-01

465

An Analysis of Absorbing Times of Quantum Walks  

Microsoft Academic Search

Quantum walks are expected to provide useful algorithmic tools for quantum computation. This paper introduces absorbing probability and time of quantum walks and gives both numerical simulation results and theoretical analyses on Hadamard walks on the line and symmetric walks on the hypercube from the viewpoint of absorbing probability and time.

Tomohiro Yamasaki; Hirotada Kobayashi; Hiroshi Imai

2002-01-01

466

Coagulation monitor based on serum migration through absorbent materials  

Microsoft Academic Search

I describe a method to measure blood coagulation prop- erties, based on the hypothesis that the distance the serum component of a clotted plasma sample moves through a suitable absorbent material should be propor- tional to the blood's ability to clot. A simple apparatus was constructed to test this principle, in which an absorbent strip contacts clotted plasma samples. At

Paul E. Wilson

467

Absorbing-state phase transitions with extremal dynamics  

NASA Astrophysics Data System (ADS)

Extremal dynamics represents a path to self-organized criticality in which the order parameter is tuned to a value of zero. The order parameter is associated with a phase transition to an absorbing state. Given a process that exhibits a phase transition to an absorbing state, we define an “extremal absorbing” process, providing the link to the associated extremal (nonabsorbing) process. Stationary properties of the latter correspond to those at the absorbing-state phase transition in the former. Studying the absorbing version of an extremal dynamics model allows to determine certain critical exponents that are not otherwise accessible. In the case of the Bak-Sneppen (BS) model, the absorbing version is closely related to the “ f -avalanche” introduced by Paczuski, Maslov, and Bak [Phys. Rev. E 53, 414 (1996)], or, in spreading simulations to the “BS branching process” also studied by these authors. The corresponding nonextremal process belongs to the directed percolation universality class. We revisit the absorbing BS model, obtaining refined estimates for the threshold and critical exponents in one dimension. We also study an extremal version of the usual contact process, using mean-field theory and simulation. The extremal condition slows the spread of activity and modifies the critical behavior radically, defining an “extremal directed percolation” universality class of absorbing-state phase transitions. Asymmetric updating is a relevant perturbation for this class, even though it is irrelevant for the corresponding nonextremal class.

Dickman, Ronald; Garcia, Guilherme J. M.

2005-06-01

468

Resveratrol Is Absorbed in the Small Intestine as Resveratrol Glucuronide  

Microsoft Academic Search

We have studied the absorption and metabolism of resveratrol in the jejunum in an isolated rat small intestine model. Only small amounts of resveratrol were absorbed across the enterocytes of the jejunum and ileum unmetabolised. The major compound detected on the serosal side was the glucuronide conjugate of resveratrol (96.5% ± 4.6 of the amount absorbed) indicating the susceptibility of

Gunter Kuhnle; Jeremy P. E. Spencer; George Chowrimootoo; Hagen Schroeter; Edward S. Debnam; S. Kaila S. Srai; Catherine Rice-Evans; Ulrich Hahn

2000-01-01

469

CFRP-based broad-band Radar Absorbing Materials  

Microsoft Academic Search

Strong interest in radar absorbing materials (RAMs) took place with years due to their extensive sectors of application. RAMs are coatings whose electric and magnetic properties allow the absorption of microwave energy over certain frequencies. In particular, RAMs are very effective means of Radar Cross Section (RCS) reduction in the context of stealth technology. RCS reduction requires absorbers with broad-band

C. Mitrano; A. Balzano; M. Bertacca; M. Flaccavento; R. Mancinelli

2008-01-01

470

Application of Impedance Loading to Geometric Transition Radar Absorbent Material  

Microsoft Academic Search

This paper describes a novel, lightweight technique for significantly improving the low-frequency reflectivity performance of conventional geometric transition radar absorbent materials as used typically in anechoic chamber facilities for electromagnetic compatibility testing. The improvement is achieved by the inclusion of impedance-loading elements within the base region of the absorber, and these are implemented in the form of one or more

Kenneth Lee Ford; Barry Chambers

2007-01-01

471

Computational method for radar absorbing composite lattice grids  

Microsoft Academic Search

Composite lattice grids reinforced by glass fibers (GFRC) and carbon fibers (CFRC) filled with spongy materials can be designed as lightweight radar absorbing structures (RAS). In the present paper, a computational approach based on periodic moment method (PMM) has been developed to calculate reflection coefficients of radar absorbing composite lattice grids. Total reflection backing (TRB) is considered directly in our

Mingji Chen; Yongmao Pei; Daining Fang

2009-01-01

472

Hybrid multilayer structures for use as microwave absorbing material  

Microsoft Academic Search

The aim of this study is the in situ processing of flexible multilayer radar absorbing structures materials based on polymeric substrates impregnated with polyaniline conducting polymer. There is a growing interest in the development of low density flexible absorber material for applications that require the reduction of the reflectivity of targets with complex shapes and improvement of the ease of

Luiza de C. Folgueras; Mirabel C. Rezende

2007-01-01

473

A model of an ammonia-water falling film absorber  

Microsoft Academic Search

This paper describes a model of the absorption process in a falling film ammonia-water absorber. The model consists of two ordinary, first-order differential equations with suitable inlet and interface conditions. The model was validated by comparing its predictions to experimental data. The objective of the work was to define strategies to enhance the absorption process in order to downsize absorbers.

H. Perez-blanco

1988-01-01

474

Composite sandwich constructions for absorbing the electromagnetic waves  

Microsoft Academic Search

RAS (radar absorbing structures) is a key component for weapon systems such as aircrafts, warships, and missiles to achieve both the stealth performance by absorbing EM (Electromagnetic) waves incident on and load bearing capability. In this work, the RAS was fabricated as sandwich constructions composed of nanocomposite, carbon fabric\\/epoxy composite, and PVC foam. The nanocomposite composed of E-glass fabric, epoxy

Po Chul Kim; Dai Gil Lee

2009-01-01

475

Hafnium as a neutron absorber in research reactors  

Microsoft Academic Search

Research reactors usually require the periodic replacement of control rods because of the burnup of the neutron absorber material, even if devices have been mainly withdrawn. The purpose of this paper is the study of the reactivity worth of hafnium as a neutron absorber in the multi-purpose-type research reactor (MPTRR). The MPTRR design develops 20 MW, and it is configured

F. E. Jatuff; E. A. Villarino

1995-01-01

476

The behaviour of control rod absorber under irradiation  

Microsoft Academic Search

Increase of rod diameters and cracking of PWR control rod claddings may occur in operation. In order to understand the contribution of the absorber properties to this damage, EDF and FRAMATOME launched a programme of examinations concerning the silver–indium–cadmium alloy constituting the absorber bars. Density measurements and microstructural investigations such as micrography, microanalysis were carried out in the EDF Hot

J. Bourgoin; F. Couvreur; D. Gosset; F. Defoort; M. Monchanin; X. Thibault

1999-01-01

477

Fundamental research on oscillating water column wave power absorbers  

Microsoft Academic Search

An oscillating water column (OWC) wave power absorber is one of the most promising devices, as well as the Salter Duck and the Clam. This paper presents a simple prediction method, in which the equivalent floating body approximation is used, for absorbing wave power characteristics of an oscillating water column device. The effects of the compressibility of air and inertia

H. Maeda; W. Kato; T. Kinoshita; K. Masuda

1985-01-01

478

A Study of Resonant Absorbers for Underwater Sound.  

National Technical Information Service (NTIS)

In the first part of the work a simple model of a resonant absorber is proposed from which is derived an expression relating the acoustic impedance at the surface of the absorber with the dynamic modulus of the material from which it is made. Results are ...

W. Meeks

1965-01-01

479

Experimental development and theoretical studies of radio-frequency absorbers  

Microsoft Academic Search

A mathematical model based on the equivalence with a sequence of lossy transmission lines has been developed and applied, by numerical calculus, to the study of radio-frequency absorbers of piramidal shape, made of polyurethane foam impregnated with finely powered carbon black. The model has been used to find the expected performance of absorbers with different electrical conductivities in the microwave

J. L. L. M. Massa

1991-01-01

480

Design of Salisbury screen absorbers using dielectric lossy sheets  

Microsoft Academic Search

In this study, we present design and manufacturing technology for the Salisbury screen type radar absorbing structure (RAS) in Xband. The RAS is composed of a dielectric lossy sheet and an E-glass fabric\\/epoxy composite laminate as the spacer. This RAS has a broader absorbing bandwidth and much thinner spacer than those of the conventional one which uses a 377 ?\\/?

Jinbong Kim

2011-01-01

481

Nylon shock absorber prevents injury to parachute jumpers  

NASA Technical Reports Server (NTRS)

Nylon shock absorbers reduce the canopy-opening shock of a parachute to a level that protects the wearer from injury. A shock absorber is mounted on each of the four risers between the shroud lines and the harness. Because of their size and location, they pose no problem in repacking the chute and harness after a jump.

Mandel, J. A.

1966-01-01

482

Selective absorbers from substituted magnetite-based coatings  

Microsoft Academic Search

Selective solar absorbers have been prepared for industrial applications with an original treatment -- chemical conversion of the surface -- of ferritic stainless steels. They present a high solar absorbance ((alpha) s approximately equals 0.95), a low emittance ((xi) approximately equals 0.20), a high thermal stability, and a high resistance to corrosion by atmospheric agents. Char