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1

Anomalous Microwave Emission in NGC 6946  

NASA Astrophysics Data System (ADS)

The dust-correlated Anomalous Microwave Emission (AME), attributed to electric dipole emission from spinning dust grains, has been observed in the Galaxy for over a decade. In 2010, Murphy et al. presented GBT observations of NGC 6946, which showed strong evidence of this emission in several extra-nuclear regions, making it the first extra-galactic detection of the AME. We present follow-up observations at 3mm and 1cm with CARMA and synthesize composite SEDs using maps from Spitzer, Herschel, GISMO, VLA, and WSRT. We confirm the detection of AME in extra-nuclear region 4 and present evidence of anomalous emission in other regions of the galaxy. We discuss the inferred properties of both the dust and the environment in these regions based upon the composite SEDs.

Hensley, Brandon; Murphy, E. J.

2013-01-01

2

The large-scale anomalous microwave emission revisited by WMAP.  

NASA Astrophysics Data System (ADS)

We present a new study of the high latitude galactic contributions to the millimeter sky, based on an analysis of the WMAP data combined with several templates of dust emission (DIRBE/COBE and FIRAS/COBE) and gas tracers (HI and Halpha). To study the IR to millimeter properties of the diffuse sky at high galactic latitude, we concentrate on the emission correlated with the HI gas. We compute the emission spectrum of the dust/free-free/synchrotron components associated with HI gas from low to large column densities. A significant residual WMAP emission over the free-free, synchrotron and the dust contributions is found from 3.2 to 9.1 mm. We show that this residual WMAP emission (normalised to 1020 atoms/cm2) (1) exhibits a constant spectrum from 3.2 to 9.1 mm and (2) significantly decreases in amplitude when NHI increases, contrary to the HI-normalised far-infrared emission which stays rather constant. It is thus very likely that the residual WMAP emission is not associated with the Large Grain dust component. The decrease in amplitude with increasing opacity ressembles in fact to the decrease of the transiently heated dust grain emission observed in dense interstellar clouds. This is supported by an observed decrease of the HI-normalised 60 mu m emission with HI column densities. Although this result should be interpreted with care due to residual zodiacal contaminations at 60 mu m, it suggests that the WMAP excess emission is associated with the small transiently heated dust particles. On the possible models of this so-called ``anomalous microwave emission'' linked to the small dust particles are the spinning dust and the excess millimeter emission of the small grains, due to the cold temperatures they can reach between two successive impacts with photons. The Wilkinson Microwave Anisotropy Probe (WMAP) is the result of a partnership between Princeton University and NASA's Goddard Space Flight Center.}

Lagache, G.

2003-07-01

3

Observations and Theory of the Anomalous Microwave Emission  

NASA Astrophysics Data System (ADS)

The recently discovered Anomalous Microwave Emission (AME) presents a potential new probe of interstellar dust. Peaking at around 30GHz, having a width of several tens of GHz, and appearing to be highly dust-correlated, this continuum emission is commonly assumed to be due very small, rapidly spinning dust grains. Directed study of the AME may therefore provide a new handle on these grains and their environments. I will present three projects aimed at advancing our understanding of this emission. The first is a new, analytical derivation of radiation from spinning dust grains, bridging the gap between the precise models and realistic observations. The second is a joint CARMA/AMI survey of Planck Early Cold Clumps, searching for predicted spinning dust emission. The third is a correlation analysis of diffuse microwave emission from the North Celestial Pole, combining a new 5GHz map from the C-Band All-Sky Survey (C-BASS) with existing radio, WMAP, IRAS, and H? maps. This work was supported in part by the NSF (AST-1212217).

Stevenson, Matthew; Readhead, A. C.; Pearson, T. J.; Cleary, K.; Tibbs, C.; Villadsen, J.; Hirata, C. M.; Paladini, R.; Muchovej, S.; Grainge, K.; Perrott, Y.; Rumsey, C.; Scaife, A.; C-BASS Collaboration

2013-01-01

4

Anomalous Microwave Emission from the H II Region RCW175  

NASA Astrophysics Data System (ADS)

We present evidence for anomalous microwave emission in the RCW175 H II region. Motivated by 33 GHz 13' resolution data from the Very Small Array (VSA), we observed RCW175 at 31 GHz with the Cosmic Background Imager (CBI) at a resolution of 4'. The region consists of two distinct components, G29.0-0.6 and G29.1-0.7, which are detected at high signal-to-noise ratio. The integrated flux density is 5.97 ± 0.30 Jy at 31 GHz, in good agreement with the VSA. The 31 GHz flux density is 3.28 ± 0.38 Jy (8.6?) above the expected value from optically thin free-free emission based on lower frequency radio data and thermal dust constrained by IRAS and WMAP data. Conventional emission mechanisms such as optically thick emission from ultracompact H II regions cannot easily account for this excess. We interpret the excess as evidence for electric dipole emission from small spinning dust grains, which does provide an adequate fit to the data.

Dickinson, C.; Davies, R. D.; Allison, J. R.; Bond, J. R.; Casassus, S.; Cleary, K.; Davis, R. J.; Jones, M. E.; Mason, B. S.; Myers, S. T.; Pearson, T. J.; Readhead, A. C. S.; Sievers, J. L.; Taylor, A. C.; Todorovi?, M.; White, G. J.; Wilkinson, P. N.

2009-01-01

5

Planck new results: Anomalous Microwave Emission from Galactic clouds  

NASA Astrophysics Data System (ADS)

Planck data, combined with multi-frequency data, has allowed accurate spectra from the radio to far infra-red to be constructed for bright regions in our Galaxy. Spectra for the Perseus and Rho Ophiuchi molecular clouds show strong evidence for Anomalous Microwave Emission (AME) at frequencies 10-100 GHz. The residual spectra, after subtraction of the free-free, CMB and thermal dust components, represent the most precise spectra of AME to date. They show a peaked spectral shape, with a peak at ~30 GHz, as expected from electric dipole radiation from small spinning dust grains. A plausible physical model for the spinning dust can provide a good fit to the data, where the higher density molecular gas accounts for most of the AME, while the lower density atomic gas appears to play a minor role. A search for new AME regions with the Planck data has revealed a number of new candidates showing excess emission at 20-60 GHz. We make a first statistical analysis of AME and non-AME Galactic clouds. We show that a significant fraction of this new sample shows evidence of AME. The emissivity of the AME is comparable to previous detections and is shown to be tightly correlated with thermal dust tracers in the sub-mm and IR. We investigate correlations of derived parameters with the AME emissivity to investigate the nature of the spinning dust.

Davis, Richard; Dickinson, Clive

2012-07-01

6

AMI Observations of the Anomalous Microwave Emission in the Perseus Molecular Cloud  

NASA Astrophysics Data System (ADS)

We present observations of the known anomalous microwave emission region, G159.6-18.5, in the Perseus molecular cloud at 16 GHz performed with the Arcminute Microkelvin Imager Small Array. These are the highest angular resolution observations of G159.6-18.5 at microwave wavelengths. By combining these microwave data with infrared observations between 5.8 and 160 ?m from the Spitzer Space Telescope, we investigate the existence of a microwave-infrared correlation on angular scales of ~2'. We find that the overall correlation appears to increase toward shorter infrared wavelengths, which is consistent with the microwave emission being produced by electric dipole radiation from small, spinning dust grains. We also find that the microwave-infrared correlation peaks at 24 ?m (6.7?), suggesting that the microwave emission is originating from a population of stochastically heated small interstellar dust grains rather than polycyclic aromatic hydrocarbons.

Tibbs, C. T.; Scaife, A. M. M.; Dickinson, C.; Paladini, R.; Davies, R. D.; Davis, R. J.; Grainge, K. J. B.; Watson, R. A.

2013-05-01

7

AMI Observations of the Anomalous Microwave Emission in the Perseus Molecular Cloud  

NASA Astrophysics Data System (ADS)

We present observations of the known anomalous microwave emission region, G159.6-18.5, in the Perseus molecular cloud at 16 GHz performed with the Arcminute Microkelvin Imager Small Array. These are the highest angular resolution observations of this dust feature at microwave wavelengths. By combining these microwave data with observations from the Spitzer Space Telescope, we investigate the existence of a microwave - IR correlation on angular scales of ?2 arcmin. We find that the overall correlation appears to increase towards shorter wavelengths which is consistent with the microwave emission being produced by electric dipole radiation from small, spinning dust grains. We also find that the microwave - IR correlation peaks at 24 ?m (5.8?), suggesting that the microwave emission is originating from the warmer, more excited small interstellar dust grains rather than the polycyclic aromatic hydrocarbons.

Tibbs, Christopher; Scaife, A.; Dickinson, C.; Paladini, R.; Davies, R.; Davis, R.; Grainge, K.; Watson, R.

2013-01-01

8

Very Small Array observations of the anomalous microwave emission in the Perseus region  

NASA Astrophysics Data System (ADS)

The dust complex G159.6-18.5 in the Perseus region has previously been observed with the COSMOSOMAS experiment on angular scales of ~1°, and was found to exhibit anomalous microwave emission. We present the first high angular resolution observations of this dust complex, performed with the Very Small Array (VSA) at 33GHz, to help increase the understanding of the nature of this anomalous emission. On the angular scales observed with the VSA (~10-40arcmin), G159.6-18.5 consists of five distinct components, all of which are found to exhibit an excess of emission at 33GHz that is highly correlated with far-infrared emission. Within the region, we find a range of physical conditions: one of the features, which is associated with the reflection nebula IC 348, has a dust emissivity comparable to that of HII regions, while the other four features have values in agreement with previous observations of intermediate Galactic latitudes. We provide evidence that all of these compact components have anomalous emission that is consistent with electric dipole emission from very small, rapidly rotating dust grains. We find that these five components contribute ~10 per cent to the flux density of the diffuse extended emission detected by COSMOSOMAS, implying that the bulk of the anomalous emission in Perseus is diffuse and not concentrated in these compact components.

Tibbs, Christopher T.; Watson, Robert A.; Dickinson, Clive; Davies, Rodney D.; Davis, Richard J.; Buckmaster, Simon; Del Burgo, Carlos; Franzen, Thomas M. O.; Génova-Santos, Ricardo; Grainge, Keith; Hobson, Michael P.; Padilla-Torres, Carmen P.; Rebolo, Rafael; Rubiño-Martín, José Alberto; Saunders, Richard D. E.; Scaife, Anna M. M.; Scott, Paul F.

2010-03-01

9

VSA Observations of the Anomalous Microwave Emission in the Perseus Region  

Microsoft Academic Search

The dust feature G159.6--18.5 in the Perseus region has previously been\\u000aobserved with the COSMOSOMAS experiment \\\\citep{Watson:05} on angular scales of\\u000a$\\\\approx$ 1$^{\\\\circ}$, and was found to exhibit anomalous microwave emission.\\u000aWe present new observations of this dust feature, performed with the Very Small\\u000aArray (VSA) at 33 GHz, to help increase the understanding of the nature of this\\u000aanomalous

Christopher T. Tibbs; Robert A. Watson; Clive Dickinson; Rodney D. Davies; Richard J. Davis; Carlos del Burgo; Thomas M. O. Franzen; Ricardo Génova-Santos; Keith Grainge; Michael P. Hobson; Carmen P. Padilla-Torres; Rafael Rebolo; Jóse Alberto Rubiño-Martín; Richard D. E. Saunders; Anna M. M. Scaife; Paul F. Scott

2009-01-01

10

New constraints on the polarization of anomalous microwave emission in nearby molecular clouds  

NASA Astrophysics Data System (ADS)

Anomalous microwave emission (AME) has been previously studied in two well-known molecular clouds and is thought to be due to electric dipole radiation from small spinning dust grains. It is important to measure the polarization properties of this radiation both for component separation in future cosmic microwave background (CMB) experiments and also to constrain dust models. We have searched for linearly polarized radio emission associated with the ? Ophiuchi and Perseus molecular clouds using WMAP 7-year data. We found no significant polarization within an aperture of 2° diameter. The upper limits on the fractional polarization of spinning dust in the ? Ophiuchi cloud are 1.7, 1.6 and 2.6 per cent (at 95 per cent confidence level) at K, Ka and Q bands, respectively. In the Perseus cloud we derived upper limits of 1.4, 1.9 and 4.7 per cent, at K, Ka and Q bands, respectively; these are similar to those found by López-Caraballo et al. If AME at high Galactic latitudes has a similarly low level of polarization, this will simplify component separation for CMB polarization measurements. We can also rule out single domain magnetic dipole radiation as the dominant emission mechanism for the 20-40 GHz. The polarization levels are consistent with spinning dust models.

Dickinson, C.; Peel, M.; Vidal, M.

2011-11-01

11

DETECTION OF ANOMALOUS MICROWAVE EMISSION IN THE PLEIADES REFLECTION NEBULA WITH WILKINSON MICROWAVE ANISOTROPY PROBE AND THE COSMOSOMAS EXPERIMENT  

SciTech Connect

We present evidence for anomalous microwave emission (AME) in the Pleiades reflection nebula, using data from the seven-year release of the Wilkinson Microwave Anisotropy Probe and from the COSMOSOMAS (Cosmological Structures on Medium Angular Scales) experiment. The flux integrated in a 1 Degree-Sign radius around R.A. = 56.{sup 0}24, decl. = 23.{sup 0}78 (J2000) is 2.15 {+-} 0.12 Jy at 22.8 GHz, where AME is dominant. COSMOSOMAS data show no significant emission, but allow one to set upper limits of 0.94 and 1.58 Jy (99.7% confidence level), respectively, at 10.9 and 14.7 GHz, which are crucial to pin down the AME spectrum at these frequencies, and to discard any other emission mechanisms which could have an important contribution to the signal detected at 22.8 GHz. We estimate the expected level of free-free emission from an extinction-corrected H{alpha} template, while the thermal dust emission is characterized from infrared DIRBE data and extrapolated to microwave frequencies. When we deduct the contribution from these two components at 22.8 GHz, the residual flux, associated with AME, is 2.12 {+-} 0.12 Jy (17.7{sigma}). The spectral energy distribution from 10 to 60 GHz can be accurately fitted with a model of electric dipole emission from small spinning dust grains distributed in two separated phases of molecular and atomic gas, respectively. The dust emissivity, calculated by correlating the 22.8 GHz data with 100 {mu}m data, is found to be 4.36 {+-} 0.17 {mu}K (MJy sr{sup -1}){sup -1}, a value considerably lower than in typical AME clouds, which present emissivities of {approx}20 {mu}K (MJy sr{sup -1}){sup -1}, although higher than the 0.2 {mu}K (MJy sr{sup -1}){sup -1} of the translucent cloud LDN 1780, where AME has recently been claimed. The physical properties of the Pleiades nebula, in particular its low extinction A{sub V} {approx} 0.4, indicate that this is indeed a much less opaque object than those where AME has usually been studied. This fact, together with the broad knowledge of the stellar content of this region, provides an excellent testbed for AME characterization in physical conditions different from those generally explored up to now.

Genova-Santos, R.; Rebolo, R.; Rubino-Martin, J. A.; Lopez-Caraballo, C. H.; Hildebrandt, S. R. [Instituto de Astrofisica de Canarias, C/Via Lactea s/n, E-38200 La Laguna, Tenerife (Spain)

2011-12-10

12

Planck early results. XX. New light on anomalous microwave emission from spinning dust grains  

NASA Astrophysics Data System (ADS)

Anomalous microwave emission (AME) has been observed by numerous experiments in the frequency range ~10-60 GHz. Using Planck maps and multi-frequency ancillary data, we have constructed spectra for two known AME regions: the Perseus and ? Ophiuchi molecular clouds. The spectra are well fitted by a combination of free-free radiation, cosmic microwave background, thermal dust, and electric dipole radiation from small spinning dust grains. The spinning dust spectra are the most precisely measured to date, and show the high frequency side clearly for the first time. The spectra have a peak in the range 20-40 GHz and are detected at high significances of 17.1? for Perseus and 8.4? for ? Ophiuchi. In Perseus, spinning dust in the dense molecular gas can account for most of the AME; the low density atomic gas appears to play a minor role. In ? Ophiuchi, the ~30 GHz peak is dominated by dense molecular gas, but there is an indication of an extended tail at frequencies 50-100 GHz, which can be accounted for by irradiated low density atomic gas. The dust parameters are consistent with those derived from other measurements. We have also searched the Planck map at 28.5 GHz for candidate AME regions, by subtracting a simple model of the synchrotron, free-free, and thermal dust. We present spectra for two of the candidates; S140 and S235 are bright Hii regions that show evidence for AME, and are well fitted by spinning dust models. Corresponding author: C. Dickinson, Clive.Dickinson@manchester.ac.uk

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Bock, J. J.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Cabella, P.; Cappellini, B.; Cardoso, J.-F.; Casassus, S.; Catalano, A.; Cayón, L.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chen, X.; Chiang, L.-Y.; Chiang, C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Couchot, F.; Coulais, A.; Crill, B. P.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Gasperis, G.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Dickinson, C.; Donzelli, S.; Doré, O.; Dörl, U.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Génova-Santos, R. T.; Giard, M.; Giardino, G.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hovest, W.; Hoyland, R. J.; Huffenberger, K. M.; Jaffe, T. R.; Jaffe, A. H.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knox, L.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Leach, S.; Leonardi, R.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; MacTavish, C. J.; Maffei, B.; Maino, D.; Mandolesi, N.; Mann, R.; Maris, M.; Marshall, D. J.; Martínez-González, E.; Masi, S.; Matarrese, S.; Matthai, F.; Mazzotta, P.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, A.; Naselsky, P.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; O'Dwyer, I. J.; Osborne, S.; Pajot, F.; Paladini, R.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, T. J.; Peel, M.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Plaszczynski, S.; Platania, P.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Poutanen, T.; Prézeau, G.; Procopio, P.; Prunet, S.; Puget, J.-L.; Reach, W. T.; Rebolo, R.; Reich, W.; Reinecke, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, P.; Smoot, G. F.; Starck, J.-L.; Stivoli, F.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Torre, J.-P.; Tristram, M.; Tuovinen, J.; Umana, G.; Valenziano, L.; Varis, J.; Verstraete, L.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Watson, R.; Wilkinson, A.; Ysard, N.; Yvon, D.; Zacchei, A.; Zonca, A.

2011-12-01

13

Microwave Emission Models of Snow.  

National Technical Information Service (NTIS)

This study is concerned with the microwave emission models of dry snow and wet snow. A review of accomplished literature surveys on microwave emission models of snow is presented, which includes the characteristics of the constituents in the snow medium, ...

W. Huining

2001-01-01

14

Determination of microwave emissivity from advance microwave sounder unit measurements  

Microsoft Academic Search

This paper proposes an efficient way to retrieve the microwave emissivity from advanced microwave sounder unit (AMSU) brightness temperature measurements. In the first step, the atmospheric temperature profile, moisture profile and surface skin temperature are determined using AMSU channel 5 to 14, 18 and 19 which are less sensitive to surface radiation. In the second step, the microwave emissivity is

Allen H. Huang; Jun Li

1998-01-01

15

Anomalous Radio Emission from Dust in the Helix  

NASA Astrophysics Data System (ADS)

A by-product of experiments designed to map the cosmic microwave background is the recent detection of a new component of foreground Galactic emission. The anomalous foreground at ~10-30 GHz, unexplained by traditional emission mechanisms, correlates with 100 ?m dust emission. We use planetary nebulae (PNs) as astrophysical laboratories to test known radio emission processes and report that in the Helix the emission at 31 GHz and 100 ?m are well correlated and exhibit similar features on sky images, which are absent in H?. Upper limits on the 250 GHz continuum emission in the Helix rule out cold grains as candidates for the 31 GHz emission and provide spectroscopic evidence for an excess at 31 GHz over bremsstrahlung. We estimate that the 100 ?m-correlated radio emission, presumably due to dust, accounts for at least 20% of the 31 GHz emission in the Helix. This result strengthens previous tentative interpretations of diffuse interstellar medium spectra involving a new dust emission mechanism at radio frequencies. Very small grains, thought not to survive in evolved PNs, have not been detected in the Helix, which hampers interpreting the new component in terms of electric dipole emission from spinning grains. The observed iron depletion in the Helix favors considering the identity of this new component to be magnetic dipole emission from hot ferromagnetic grains. The reduced level of free-free continuum that we report also implies an electronic temperature of Te=4600+/-1200 K for the free-free emitting material, which is significantly lower than the temperature of 9500+/-500 K inferred from collisionally excited lines. Partly based on observations collected at the European Southern Observatory, La Silla, Chile.

Casassus, S.; Readhead, A. C. S.; Pearson, T. J.; Nyman, L.-Å.; Shepherd, M. C.; Bronfman, L.

2004-03-01

16

Emissions from cooking microwave popcorn.  

PubMed

This study characterized chemicals released into a chamber in the process of cooking microwave popcorn. Seventeen types of microwave popcorn from eight different brands were studied. The work proceeded in two phases: phase one investigated chemicals emitted during popping and opening, phase two investigated chemicals emitted at discrete intervals from 0-40 minutes post-pop opening. The research was performed using a microwave oven enclosed in a chamber with ports for air sampling of particulate matter (PM) and volatile organic compounds (VOCs). VOCs in the air samples were identified and quantified using gas chromatography/mass spectrometry (GC/MS). PM was characterized using both an aerodynamic particle sizer (APS) and a scanning mobility particle sizer (SMPS) to cover a full range of emitted sizes. The compounds measured during popping and opening included butter flavoring components such as diacetyl, butyric acid, acetoin, propylene glycol, 2-nonanone, and triacetin and bag components such as p-xylene and perfluorinated alcohol 8:2 telomer. The greatest chemical quantity is emitted when the bag is opened post-popping; more than 80% of the total chemical emissions occur at this time. PMID:17987444

Rosati, Jacky A; Krebs, Kenneth A; Liu, Xiaoyu

2007-01-01

17

Soil Moisture Information And Thermal Microwave Emission  

Microsoft Academic Search

This paper presents theoretical and experimental results that demonstrate the depth to which soil moisture can be directly measured using microwave radiometers. The experimental results also document the effect of uniform surface roughness on the response of thermal microwave emission to soil moisture. Experimental measurements were executed in July 1980 at the Texas A&M University Research Farm near College Station,

Richard W. Newton; Quentin Robert Black; Shahab Makanvand; Andrew J. Blanchard; Buford Randall Jean

1982-01-01

18

Experimental study of vegetable canopy microwave emission  

NASA Astrophysics Data System (ADS)

Experimental studies of microwave emission from vegetable canopies have been made. The measuring technique and results are presented in the paper. The aim of the studies was to test the technique for determining soil moisture content under vegetation canopies by means of microwave radiometry. Data on vegetation screening effects were obtained.

Chukhlantsev, A. A.; Golovachev, S. P.; Shutko, A. M.

19

Electron Emission Mechanism of Microwave Discharge Neutralizer  

NASA Astrophysics Data System (ADS)

Institute of Space and Astronautical Science has developed a cathodeless microwave discharge neutralizer for the microwave ion engine system. In order to clarify the electron emission mechanism of the microwave neutralizer, electron current characteristics as well as plasma parameters inside the neuralizer were measured. The electron current was greatly influenced by the material of the neutralizer orifice. Among several materials with different work functions, an orifice made of tungsten impregnated with barium-oxygen showed the best performance. It is concluded that by adopting a low-work-function material, the secondary-electron emission by the singly-charged-ion impact was emphasized, and thereby the electron current was increased.

Onodera, Noriyoshi; Takegahara, Haruki; Nishiyama, Kazutaka; Funaki, Ikko; Kuninaka, Hitoshi

20

Explaining Variations in Microwave Surface Emissivity from Passive Microwave Observations  

NASA Astrophysics Data System (ADS)

The Global Precipitation Measurement (GPM) Microwave Imager (GMI) onboard the core satellite orbits at a 65 degree inclination, providing more observations over land areas whose underlying microwave surface emissivity is subject to wider variations. The emissivity at each channel is highly correlated, suggesting that characterization for one channel should not be done independently of another. Also, the surface emissivity can change very rapidly with the onset of precipitation. Principal component analysis was performed on the emissivity retrieved from a large set of global, over-land, multi-year, clear-scene A-Train observations (AMSR-E and MHS). It is shown that the 10-89 GHz emissivity spectrum can be reconstructed from the first three principal components, which in turn were estimated directly from the observed brightness temperatures. When these coefficients were applied to entire orbits of AMSR-E data, the reconstructed emissivity exceeded unity for regions associated with the presence of over-land precipitation. Examples are shown for cases that are further subsetted by the presence and amount of previous-time precipitation.

Turk, F. J.; Haddad, Z. S.; Park, K.

2011-12-01

21

Microwave Emissions from Police Radar  

Microsoft Academic Search

This study evaluated police officers' exposures to microwaves emitted by traffic radar units. Exposure measurements were taken at approximated ocular and testicular levels of officers seated in patrol vehicles. Comparisons were made of the radar manufacturers' published maximum power density specifications and actual measured power densities taken at the antenna faces of those units. Four speed-enforcement agencies and one transportation

J. M. Fink; J. P. Wagner; J. J. Congleton; J. C. Rock

1999-01-01

22

Microwave land emissivity calculations using AMSU measurements  

Microsoft Academic Search

Atmospheric parameter retrievals over land from Advanced Microwave Sounding Unit (AMSU) measurements, such as atmospheric temperature and moisture profiles, could be possible using a reliable estimate of the land emissivity. The land surface emissivities have been calculated using six months of data, for 30 beam positions (observation zenith angles from -58° to +58°) and the 23.8-, 31.4-, 50.3-, 89-, and

Fatima Karbou; Catherine Prigent; Laurence Eymard; Juan R. Pardo

2005-01-01

23

Surveys of Microwave Emission from Air Showers  

NASA Astrophysics Data System (ADS)

A possibility of detection of microwave molecular bremsstrahlung radiation from Extensive Air Showers was reported by AMBER group [1] [2]. This method has a potential to provide a high duty cycle and a new technique for measuring longitudinal profile of EAS. To survey this microwave emission from EAS, we built prototype detectors using parabolic antenna dishes for broadcasting satellites, and we are operating detectors with a small EAS array at Osaka City Univercity. Here, we report our detector configurations and the current experimental status.

Kuramoto, Kazuyuki; Ogio, Shoichi; Iijima, Takashi; Yamamoto, Tokonatsu

2011-09-01

24

Anomalous Energy Broadening in a Compact High - Microwave Ion Source  

Microsoft Academic Search

During the last decade, the electron cyclotron resonance (ECR) ion sources have become the de facto ion source to use in various fields. The ECR ion sources are attractive because they can generate high currents and are inherently more reliable than other types of ion sources. We designed a microwave ion source that is similar to an ECR ion source.

Futeh Kao

1994-01-01

25

Observations and Models of Iapetus's Microwave Emissivity  

NASA Astrophysics Data System (ADS)

Iapetus is one of the most unusual moons in the solar system and is best known for its stark hemispherical albedo contrast at optical wavelengths. However, only a handful of previous observations have explored whether this contrast also manifests itself in the thermal emission. While Iapetus's daytime infrared brightness temperature only varies by about 10K, our observations with the Green Bank Telescope (GBT) have shown that Iapetus's microwave brightness temperature at the Ka-Band (26-40 GHz) can vary by as much as 60K, with effective emissivities dropping to less than 0.3 on the bright trailing hemisphere. We have also observed that the variation is substantially less at 3.3 mm. This behavior is unprecedented in the astronomical literature, but not entirely unprecedented in the literature from the remote sensing branch of climate science. Climate scientists have made extensive studies of Earth's microwave emissivities from 10 to 200 GHz and found similarly shaped features in dry snowpacks and glaciers. Here we present an attempt to model Iapetus's microwave emissivity using various snow models from the climate science literature and report on the final observations from a GBT observing campaign. This research has been supported by the NRAO pre-doc program and the Virginia Space Grant Consortium graduate fellowship program.

Ries, Paul

2012-01-01

26

Vacuum field energy and spontaneous emission in anomalously dispersive cavities  

SciTech Connect

Anomalously dispersive cavities, particularly white-light cavities, may have larger bandwidth to finesse ratios than their normally dispersive counterparts. Partly for this reason, they have been proposed for use in laser interferometer gravitational-wave observatory (LIGO)-like gravity-wave detectors and in ring-laser gyroscopes. In this paper we analyze the quantum noise associated with anomalously dispersive cavity modes. The vacuum field energy associated with a particular cavity mode is proportional to the cavity-averaged group velocity of that mode. For anomalously dispersive cavities with group index values between 1 and 0, this means that the total vacuum field energy associated with a particular cavity mode must exceed ({h_bar}/2{pi}){omega}/2. For white-light cavities in particular, the group index approaches zero and the vacuum field energy of a particular spatial mode may be significantly enhanced. We predict enhanced spontaneous emission rates into anomalously dispersive cavity modes and broadened laser linewidths when the linewidth of intracavity emitters is broader than the cavity linewidth.

Bradshaw, Douglas H.; Di Rosa, Michael D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2011-05-15

27

Two microwave land emissivity parameterizations suitable for AMSU observations  

Microsoft Academic Search

In this work, two microwave emissivity parameterizations are proposed to estimate the land emissivity at Advanced Microwave Sounding Units (AMSU) frequencies and scanning conditions in order to help processing AMSU measurements over land surfaces. Both parameterizations are derived from previously calculated land emissivities directly from satellite observations and take into account different surface types from bare soil to areas with

Fatima Karbou

2005-01-01

28

Anomalous galvanomagnetism, cyclotron resonance, and microwave spectroscopy of topological insulators  

NASA Astrophysics Data System (ADS)

The surface quantum Hall state, magnetoelectric phenomena, and their connection to axion electrodynamics have been studied intensively for topological insulators. One of the obstacles for observing such effects comes from nonzero conductivity of the bulk. To overcome this obstacle, we propose to use an external magnetic field to suppress the conductivity of the bulk carriers. The magnetic field dependence of galvanomagnetic and electromagnetic responses of the whole system shows anomalies due to broken time-reversal symmetry of the surface quantum Hall state, which can be used for its detection. In particular, we find negative linear dc magnetoresistivity and a quadratic field dependence of the Hall angle, shifted rf cyclotron resonance, nonanalytic microwave transmission coefficient, and saturation of the Faraday rotation angle with increasing magnetic field or wave frequency.

Tkachov, G.; Hankiewicz, E. M.

2011-07-01

29

A Cherenkov-emission Microwave Source.*  

NASA Astrophysics Data System (ADS)

In an unmagnetized plasma, there is no Cherenkov emission because the phase velocity ?_? of light is greater than c. In a magnetized plasma, the situation is completely changed. There is a rich variety of plasma modes with phase velocities ?_? <= c which can couple to a fast particle. In the magnetized plasma, a fast particle, a particle beam, or even a short laser pulse excites a Cherenkov wake that has both electrostatic and electromagnetic components. Preliminary simulations indicate that at the vacuum/plasma boundary, the wake couples to a vacuum microwave with an amplitude equal to the electromagnetic component in the plasma. For a weakly magnetized plasma, the amplitude of the out-coupled radiation is approximately ?c / ?p times the amplitude of the wake excited in the plasma by the beam, and the frequency is approximately ?_p. Since plasma wakes as high as a few GeV/m are produced in current experiments, the potential for a high-power (i.e., GWatt) coherent microwave to THz source exists. In this talk, a brief overview of the scaling laws will be presented, followed by 1-D and 2-D PIC simulations. Prospects for a tuneable microwave source experiment based on this mechanism at the UCLA plasma wakefield accelerator facility will be discussed. Work supported by AFOSR Grant #F4 96200-95-0248 and DOE Grant # DE-FG03-92ER40745. ^1Now at Hughes Research Laboratories, Malibu, CA 90265.

Lai, C. H.; Yoshii, J.; Katsouleas, T.; Hairapetian, G.; Joshi, C.; Mori, W.

1996-11-01

30

A Cherenkov-emission Microwave Source*  

NASA Astrophysics Data System (ADS)

In an unmagnetized plasma, there is no Cherenkov emission because the phase velocity vf of light is greater than c. In a magnetized plasma, the situation is completely changed. There is a rich variety of plasma modes with phase velocities vf 2 c which can couple to a fast particle. In the magnetized plasma, a fast particle, a particle beam, or even a short laser pulse excites a Cherenkov wake that has both electrostatic and electromagnetic components. Preliminary simulations indicate that at the vacuum/plasma boundary, the wake couples to a vacuum microwave with an amplitude equal to the electromagnetic component in the plasma. For a weakly magnetized plasma, the amplitude of the out-coupled radiation is approximately wc/wp times the amplitude of the wake excited in the plasma by the beam, and the frequency is approximately wp. Since plasma wakes as high as a few GeV/m are produced in current experiments, the potential for a high-power (i.e., GWatt) coherent microwave to THz source exists. In this talk, a brief overview of the scaling laws will be presented, followed by 1-D and 2-D PIC simulations. Prospects for a tuneable microwave source experiment based on this mechanism at the UCLA plasma wakefield accelerator facility will be discussed. *Work supported by AFOSR Grant #F4 96200-95-0248 and DOE Grant # DE-FG03-92ER40745. 1Now at Hughes Research Laboratories, Malibu, CA 90265

Lai, C. H.; Yoshii, J.; Katsouleas, T.; Hairapetian1, G.; Joshi, C.; Mori, W.

1996-11-01

31

Development of a global microwave land surface emissivity retrieval  

Microsoft Academic Search

Microwave remote sensing over land has lagged behind remote sensing over oceans. This is due to the larger land emissivity values and their changes on daily to seasonal timescales. The lack of surface emissivity knowledge has hindered full exploitation of the capabilities of operational satellite sensors such as AMSU and SSM\\/I in remote sensing and data assimilation. Microwave land surface

John M. Forsythe; Andrew S. Jones; Thomas H. Vonder Haar

2004-01-01

32

Search for microwave emission from ultrahigh energy cosmic rays  

NASA Astrophysics Data System (ADS)

We present a search for microwave emission from air showers induced by ultrahigh energy cosmic rays with the microwave detection of air showers experiment. No events were found, ruling out a wide range of power flux and coherence of the putative emission, including those suggested by recent laboratory measurements.

Alvarez-Muñiz, J.; Berlin, A.; Bogdan, M.; Bohá?ová, M.; Bonifazi, C.; Carvalho, W. R., Jr.; de Mello Neto, J. R. T.; Facal San Luis, P.; Genat, J. F.; Hollon, N.; Mills, E.; Monasor, M.; Privitera, P.; Reyes, L. C.; Rouille d'Orfeuil, B.; Santos, E. M.; Wayne, S.; Williams, C.; Zas, E.; Zhou, J.

2012-09-01

33

A microwave emissivity model of sea surface under wave breaking  

NASA Astrophysics Data System (ADS)

With the effective medium approximation theory of composites, a remedial model is proposed for estimating the microwave emissivity of sea surface under wave breaking driven by strong wind on the basis of an empirical model given by Pandey and Kakar. In our model, the effects of the shapes of seawater droplets and the thickness of whitecap layer (i.e. a composite layer of air and sea water droplets) over the sea surface on the microwave emissivity are investigated by calculating the effective dielectric constant of whitecaps layer. The wind speed is included in our model and the responses of water droplets shapes, such as sphere and ellipsoid, to the emissivity are also discussed at different microwave frequencies. The model is in good agreement with the experimental data of microwave emissivity of sea surface at microwave frequencies of 6.6, 10.7 and 37GHz.

Wei, En-Bo; Ge, Yong

2005-06-01

34

Microwave Emission Observations on the Maryland Centrifugal Experiment  

NASA Astrophysics Data System (ADS)

Microwave emission in the electron cyclotron range has been observed axially and radially on the Maryland Centrifugal Experiment. Microwave emission is measured in two bands, 8.5-12.5 GHz and 30.0-40.0 GHz using standard superheterodyne detectors with a noise temperature around 4 eV. If the plasma density is less than 10^19/m^3 then the axial emission is consistent with cyclotron emission in the whistler mode. However there is evidence that the signal is contaminated by reflections. The radial emission is consistent with electron Bernstein emission, appearing at the second harmonic of the cyclotron frequency and is polarized perpendicular to the magnetic field.

Reid, Remington

2012-10-01

35

Microwave emission of soil freezing and thawing observed by a truck-mounted microwave radiometer  

Microsoft Academic Search

This article presents a study of the interference effect of the microwave emission of soil during freezing and thawing processes. The microwave brightness temperature (TB) was measured at the C (6.925 GHz), X (10.65 GHz), K (18.7 GHz) and Ka (36.5 GHz) bands using a truck-mounted dual-polarized microwave radiometer. Obvious TB oscillation behaviour was shown in the results, which were

Shaojie Zhao; Lixin Zhang; Yongpan Zhang; Lingmei Jiang

2012-01-01

36

Retrieval of snow surface microwave emissivity from the advanced microwave sounding unit  

Microsoft Academic Search

Satellite data assimilation in numerical weather prediction systems requires information on microwave snow surface emissivity in a wide wavelength range. However, the existing models perform poorly for stratified snow or aged snow especially at high frequencies such that they are inapplicable for various snow types. The brightness temperatures at the window channels of the advanced microwave sounding unit (AMSU) are

Banghua Yan; Fuzhong Weng; Huan Meng

2008-01-01

37

Microwave thermal emission from Iapetus' dark terrains  

NASA Astrophysics Data System (ADS)

Because of its large distance from Saturn and its high inclination, the Cassini spacecraft has made only one close (altitude<25 000 km) flyby (IA49) of Iapetus : on September 10, 2007. During this opportunity, the RADAR instrument scanned the antenna beam in a north-south raster pattern, mostly over the dark terrains (named Cassini Regio) of the leading hemisphere of the moon. During this scan, it collected a unique and concurrent set of passive (radiometry) and active (scatterometry) data at 2.2-cm wavelength and with a footprint size of ~120 km (~15% of Iapetus' diameter). The Cassini radiometer measures the surface microwave thermal emission, which varies with the emissivity (or reflectivity) and physical temperature profile of the near-surface. At such a wavelength, it probes several tens of cm up to a few meters below the surface, depending on the absorbing properties of Iapetus' regolith. Combined with the concurrent active data, the radiometry data acquired during IA49 can be used to constrain the electrical and thermal properties of Iapetus' dark region thus providing clues on the physical state (roughness, porosity) and composition of these terrains whose nature and origin are still under debate. In this paper, we will report on the Cassini microwave observations recorded during IA49 in the active and passive modes and describe the radiative transfer model we have developed in order to analyze the radiometry data. Comparison with this model indicates that the thermal inertia sensed by the Cassini radar radiometer at 2.2 cm over Cassini Regio significantly exceeds that measured in the thermal infrared by the Cassini's Composite Infrared Spectrometer (CIRS) instrument (~10 in Rivera-Valentin et al., 2011). This suggests a gradient in density with depth, which is typical for planetary regoliths. The radiometer also captured the temperature asymmetry around the Equator due to heat buried in ground on seasonal timescales while the different local solar times of the equatorial observations seem to be responsible for a variation of less than 10 K in the brightness temperature recorded over Cassini Regio.

Le Gall, A.; Keihm, S.; Janssen, M. A.; Wye, L. C.; Lorenz, R. D.; West, R.

2012-04-01

38

Microwave Emission from Polar Surfaces I.  

National Technical Information Service (NTIS)

The goal of the work performed on this grant was to investigate the passive microwave signatures of arctic sea ice concentrating on new, young, and mature first-year ice types to determine the extent to which passive microwave remote sensing of the polar ...

T. C. Grenfell

1996-01-01

39

A comparison of ocean emissivity models using the Advanced Microwave Sounding Unit, the Special Sensor Microwave Imager, the TRMM Microwave Imager, and airborne radiometer observations  

NASA Astrophysics Data System (ADS)

New measurements of the permittivity of saline water at millimeter wavelengths have the potential to improve the accuracy of ocean surface emissivity models for use with microwave and millimeter-wave imaging and sounding instruments. Recent radiative transfer models employing a range of different treatments of surface ocean emissivity are compared with observations from the following microwave radiometers: Advanced Microwave Sounding Unit, Special Sensor Microwave Imager, TRMM Microwave Imager, Microwave Airborne Radiometer Scanning System, and Deimos. Emissivity models using the new permittivity model fit these observations more closely than those models which use the Klein and Swift extrapolation model.

Ellison, W. J.; English, S. J.; Lamkaouchi, K.; Balana, A.; Obligis, E.; Deblonde, G.; Hewison, T. J.; Bauer, P.; Kelly, G.; Eymard, L.

2003-11-01

40

Microwave radiometric system for biomedical 'true temperature' and emissivity measurements.  

PubMed

A novel type of radiometer is described, which solves the problem of emissivity-(mismatch)-independent noise temperature measurements by simultaneous registration of an object's apparent temperature and its reflectivity with just one microwave receiver and real-time calculation of the object's emissivity and its actual temperature. PMID:6558132

Lüdeke, K M; Köhler, J

1983-09-01

41

Detection of plutonium with the microwave plasma continuous emissions monitor  

SciTech Connect

The first successful detection of plutonium with a continuous microwave plasma emissions monitor has been demonstrated. Seven plutonium emission peaks in the 362 - 366 nm and 449 - 454 nm ranges were clearly observed. The strongest peak was at 453.62 nm. This peak and five of the other plutonium peaks were easily distinguishable from possible interference from iron emission peaks with a spectrometer resolution of 0.1 nm. 2 refs., 3 figs.

Rhee, D.Y.; Woskov, P.P. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center; Gervais, K.; Surma, J.E. [Pacific Northwest Lab., Richland, WA (United States)

1995-09-01

42

Cosmic microwave background polarization as a probe of the anomalous nature of the cold spot  

NASA Astrophysics Data System (ADS)

One of the most interesting explanations for the non-Gaussian cold spot detected in the Wilkinson Microwave Anisotropy Probe (WMAP) data by Vielva et al. is that it arises from the interaction of the cosmic microwave background radiation with a cosmic texture. In this case, a lack of polarization is expected in the region of the spot, as compared to the typical values associated to large fluctuations of a Gaussian and isotropic random field. In addition, other physical processes related to a non-linear evolution of the gravitational field could lead to a similar scenario. However, some of these alternative scenarios (e.g. a large void in the large-scale structure) have been shown to be very unlikely. In this work we characterize the polarization properties of the cold spot under both hypotheses: a large Gaussian fluctuation and an anomalous feature generated, for instance, by a cosmic texture. We also propose a methodology to distinguish between them, and we discuss its discrimination power as a function of the instrumental noise level. In particular, we address the cases of current experiments, like WMAP and Planck, and others in development as the Q, U and I Joint Tenerife Experiment (QUIJOTE). We find that for an ideal experiment with a high-polarization sensitivity, the Gaussian hypothesis could be rejected at a significance level better than 0.8 per cent. While WMAP is far from providing useful information in this respect, we find that Planck will be able to reach a significance level of around 7 per cent; in addition, we show that the ground-based experiment QUIJOTE could provide a significance level of around 1 per cent, close to the ideal case. If these results are combined with the significance level found for the cold spot in temperature, the capability of QUIJOTE and Planck to reject the alternative hypothesis becomes 0.025 and 0.124 per cent, respectively.

Vielva, P.; Martí; Nez-González, E.; Cruz, M.; Barreiro, R. B.; Tucci, M.

2011-01-01

43

Experimental verification of the anomalous skin effect in copper using emissivity measurements  

NASA Astrophysics Data System (ADS)

Spectral directional emissivity has been measured in copper between 3 and 24 ?m above room temperature. The experimental spectrum shows a weak broad peak between 7 and 14 ?m, which is much more acute for higher emission angles. However, the peak width and position are both independent of the emission angle. The experimental results are in very good agreement with the semiclassical theory of the optical properties of metals in the regime of the anomalous skin effect, in particular with the asymptotic approximation. This comparison suggests that this work shows an optical experimental evidence of the anomalous skin effect.

Echániz, T.; Setién-Fernández, I.; Pérez-Sáez, R. B.; Tello, M. J.

2013-06-01

44

A Parameterization of Effective Soil Temperature for Microwave Emission  

Microsoft Academic Search

The observed microwave brightness temperature of soils depends upon the soil temperature profile, which in a remote sensing application will not be known in any detail. In this paper we discuss a parameterization of effe:tive soil temperature, which when divided into the brightness temperature gives the emissivity, in terms of surface (To) and deep (T) soil temperatures as T =

B. J. Choudhury; T. J. Schmugge; T. Mo

1982-01-01

45

Anomalous Neutron Burst Emissions in Deuterium-Loaded Metals: Nuclear Reaction at Normal Temperature  

NASA Astrophysics Data System (ADS)

Conventional nuclear fusion occurs in plasma at temperatures greater than 107°C or when energy higher than 10 keV is applied. We report a new result of anomalous neutron emission, also called cascade neutron burst emission, from deuterium-loaded titanium and uranium deuteride samples at room temperature. The number of neutrons in the large bursts is measured as up to 2800 in less than a 64-?s interval. We suggest that the anomalous cascade neutron bursts are correlated with deuterium-loaded metals and probably the result of nuclear reactions occurring in the samples.

Jiang, Song-Sheng; Xu, Xiao-Ming; Zhu, Li-Qun; Gu, Shao-Gang; Ruan, Xi-Chao; He, Ming; Qi, Bu-Jia

2012-11-01

46

Observations of microwave continuum emission from air shower plasmas  

SciTech Connect

We investigate a possible new technique for microwave detection of cosmic-ray extensive air showers which relies on detection of expected continuum radiation in the microwave range, caused by free-electron collisions with neutrals in the tenuous plasma left after the passage of the shower. We performed an initial experiment at the Argonne Wakefield Accelerator laboratory in 2003 and measured broadband microwave emission from air ionized via high-energy electrons and photons. A follow-up experiment at the Stanford Linear Accelerator Center in the summer of 2004 confirmed the major features of the previous Argonne Wakefield Accelerator observations with better precision. Prompted by these results we built a prototype detector using satellite television technology and have made measurements suggestive of the detection of cosmic-ray extensive air showers. The method, if confirmed by experiments now in progress, could provide a high-duty cycle complement to current nitrogen fluorescence observations.

Gorham, P. W.; Lehtinen, N. G.; Varner, G. S.; Hebert, C. L.; Miki, C.; Kowalski, J.; Ruckman, L.; Stokes, B. T. [Department of Physics and Astronomy, University of Hawaii at Manoa, Honolulu, Hawaii 96822 (United States); Beatty, J. J. [Department of Physics, The Ohio State University, Columbus, Ohio 43210-1117 (United States); Connolly, A.; Saltzberg, D. [Department of Physics, University of California at Los Angeles, Los Angeles, California 90095-1547 (United States); Chen, P.; Hast, C.; Ng, J.; Reil, K.; Walz, D. [Stanford Linear Accelerator Center, 2575 Sand Island Road, Menlo Park, California 94025 (United States); Conde, M. E.; Gai, W.; Konecny, R.; Power, J. G. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2008-08-01

47

Retrieval of snow surface microwave emissivity from the advanced microwave sounding unit  

NASA Astrophysics Data System (ADS)

Satellite data assimilation in numerical weather prediction systems requires information on microwave snow surface emissivity in a wide wavelength range. However, the existing models perform poorly for stratified snow or aged snow especially at high frequencies such that they are inapplicable for various snow types. The brightness temperatures at the window channels of the advanced microwave sounding unit (AMSU) are characterized strongly by surface emissivity and are thus used in this study to retrieve snow surface emissivity from 23.8 to 150 GHz under both clear and cloudy conditions. This algorithm uses an iteration scheme associated with a two-stream radiative transfer model. The accuracy of the AMSU-retrieved snow emissivity using this algorithm is first assessed against a set of satellite-observed emissivity under clear skies and a set of simulated emissivity under cloudy conditions. The algorithm is then assessed by its application to seven consecutive snow events observed at Hagerstown, Maryland, in February 2003 and to a set of mountainous snowpacks observed at the Local Scale Observation Site of the Cold Land Processes Field Experiment in northern Colorado in February and March of 2002 and 2003. Results show that the AMSU-retrieved snow emissivity spectra are consistent with the snow emissivity model simulations of the snow events in both Maryland and Colorado. Furthermore, the impact of the AMSU-retrieved snow emissivity on global satellite data assimilation systems is investigated by applying the algorithm to the National Centers for Environmental Prediction (NCEP) Gridpoint Statistical Interpolation (GSI) system. Compared to the existing analytic land emissivity model used in the GSI system, the retrieved emissivity significantly improves the use of the AMSU sounding data in the NCEP GSI system. Therefore, the AMSU-based snow emissivity retrieval algorithm has demonstrated its potential use in the global satellite data assimilation systems.

Yan, Banghua; Weng, Fuzhong; Meng, Huan

2008-10-01

48

Development of global land surface emissivity product at AMSR-E passive microwave frequencies  

Microsoft Academic Search

Microwave land surface emissivity is one of the key inputs in Numerical Weather Prediction (NWP) models. It can be used also to classify land surface and subsurface properties such as soil moisture. The objective of this study is to develop global land effective emissivity product using passive microwave observations from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E).

Hamidreza Norouzi; Marouane Temimi; Reza Khanbilvardi

2010-01-01

49

Microwave Emission and Scattering From Deserts: Theory Compared With Satellite Measurements  

Microsoft Academic Search

The emission and scattering from desert surfaces are analyzed using simulations and measurements from the Special Sensor Microwave\\/Imager (SSM\\/I) and the Advanced Microwave Sounding Unit (AMSU) microwave satellite instruments. Deserts are virtually free of vegetation, so the satellite radiometers are able to observe the emissivities of different minerals, such as limestone and quartz. Moreover, since deserts contain little moisture, the

Norman C. Grody; Fuzhong Weng

2008-01-01

50

Anomalous Biophoton Emission during Germination Process of Red Bean  

NASA Astrophysics Data System (ADS)

Spontaneous biophoton emission was investigated for the germination and the growth process of a red bean seed. The growth process of the root of a red bean after germination was statistically investigated for a total of 2000 seeds whose average root growth dynamics was well described by a simple logistic equation. Strong biophoton emission was observed at two inflection points of the logistic curve. Namely, when maximum acceleration of the root growth occurred, maximum biophoton emission was observed.

Kai, Shoichi; Mitani, Tomohiko; Fujikawa, Masahiro

1993-03-01

51

Flutter effect and emission in the region of anomalous and normal doppler effects  

SciTech Connect

This paper investigates the excitation (flutter) of a membrane in the flow of a liquid of finite depth due to the emission of long gravity waves. It is shown that loss of stability occurs due to predominance of emission of gravity waves of negative energy (anomalous Doppler effect) over waves of positive energy. Estimates of typical increments are presented; the instability develops during a period that approximately equals 1/7 sec.

Nemtsov, B.E.

1986-06-01

52

HARD X-RAY AND MICROWAVE EMISSIONS FROM SOLAR FLARES WITH HARD SPECTRAL INDICES  

SciTech Connect

We analyze 10 flare events that radiate intense hard X-ray (HXR) emission with significant photons over 300 keV to verify that the electrons that have a common origin of acceleration mechanism and energy power-law distribution with solar flares emit HXRs and microwaves. Most of these events have the following characteristics. HXRs emanate from the footpoints of flare loops, while microwaves emanate from the tops of flare loops. The time profiles of the microwave emission show delays of peak with respect to those of the corresponding HXR emission. The spectral indices of microwave emissions show gradual hardening in all events, while the spectral indices of the corresponding HXR emissions are roughly constant in most of the events, though rather rapid hardening is simultaneously observed in some for both indices during the onset time and the peak time. These characteristics suggest that the microwave emission emanates from the trapped electrons. Then, taking into account the role of the trapping of electrons for the microwave emission, we compare the observed microwave spectra with the model spectra calculated by a gyrosynchrotron code. As a result, we successfully reproduce the eight microwave spectra. From this result, we conclude that the electrons that have a common acceleration and a common energy distribution with solar flares emit both HXR and microwave emissions in the eight events, though microwave emission is contributed to by electrons with much higher energy than HXR emission.

Kawate, T. [Kwasan and Hida Observatory, Kitashirakawa-oiwakecho, Sakyo, Kyoto 606-8502 (Japan); Nishizuka, N. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 229-8510 (Japan); Oi, A. [College of Science, Ibaraki University, Mito, Ibaraki 310-8512 (Japan); Ohyama, M. [Faculty of Education, Shiga University, 2-5-1 Hiratsu, Otsu, Shiga 1-1, Baba Hikone city, Siga 522-8522 (Japan); Nakajima, H., E-mail: kawate@kusastro.kyoto-u.ac.jp [Nobeyama Solar Radio Observatory, NAOJ, Nobeyama, Minamisaku, Nagano 384-1305 (Japan)

2012-03-10

53

Effects of Microwave Desert Surface Emissivity on AMSU-A Data Assimilation  

Microsoft Academic Search

A microwave land emissivity library has been de- veloped from the Advanced Microwave Sounding Unit (AMSU) data for improving satellite data assimilation. Over the desert, surface emissivity is classified according to soil type into several spectra. For sand, loamy sand, and sandy loam, which contain some large mineral particles, the emissivity spectra generally decrease with frequency. For other desert types

Banghua Yan; Fuzhong Weng

2011-01-01

54

Imaging of the Explosive Emission Cathode Plasma in a Vircator High-Power Microwave Source  

Microsoft Academic Search

Most pulsed high-power microwave sources use explosive electron emission cathodes to generate high current electron beams. In the explosive emission process, the current emitted through small field emission points becomes high enough to cause the cathode material to vaporize and form a plasma. Plasma characteristics, such as uniformity and expansion rate, will affect the performance of the microwave source. High-speed

John Walter; John Mankowski; James Dickens

2008-01-01

55

Concerning spikes in emission and absorption in the microwave range  

NASA Astrophysics Data System (ADS)

In some events, weak fast solar bursts (near the level of the quiet Sun) were observed in the background of numerous spikes in emission and absorption. In such a case, the background contains the noise signals of the receiver. In events on 2005 September 16 and 2002 April 14, the solar origin of fast bursts was confirmed by simultaneous recording of the bursts at several remote observatories. The noisy background pixels in emission and absorption can be excluded by subtracting a higher level of continuum when constructing the spectra. The wavelet spectrum, noisy profiles in different polarization channels and a spectrum with continuum level greater than zero demonstrates the noisy character of pixels with the lowest levels of emission and absorption. Thus, in each case, in order to judge the solar origin of all spikes, it is necessary to determine the level of continuum against the background of which the solar bursts are observed. Several models of microwave spikes are discussed. The electron cyclotron maser emission mechanism runs into serious problems with the interpretation of microwave millisecond spikes: the main obstacles are too high values of the magnetic field strength in the source (?Pe <= ?Be). The probable mechanism is the interaction of plasma Langmuir waves with ion-sound waves (l + s ? t) in a source related to shock fronts in the reconnection region.

Chernov, Gennady P.; Sych, Robert A.; Huang, Guang-Li; Ji, Hai-Sheng; Yan, Yi-Hua; Tan, Cheng-Ming

2013-01-01

56

Anomalous emission at 3.28 μm in the Titan upper atmosphere  

NASA Astrophysics Data System (ADS)

Earliest Cassini VIMS limb observations of Titan taken in October 26th, 2004 show a strong methane non-LTE limb emission at high atmospheric altitudes. During that pass at Titan, VIMS vertical resolution was about 110 km and the analyzed spectral interval corresponds to the methane emission band centered around 3.33 micron. A detailed analysis of the radiances versus altitudes shows an anomalous emission above 900 km at wavelengths close to the methane R branch (3.28 micron). The nature of such emission is under investigation. Different spectral databases and codes have been used for calculating the expected CH4 non-LTE limb emissions. The "anomalous" emission could not be reproduced using all the known CH4 bands. Its spectral position hints at a molecule containing C-H or C-N bonds. A lot of molecules and ions observed in Titan's atmosphere have been tested unsuccessfully. Benzene (C6H6), the phenyl radical (C6H5) or other aromatic species, given their spectral features and modeled abundances in the upper atmosphere, could be candidates for such emission. We choose the observation on Oct. 26th, 2004 for its very good signal to noise ratio and because of the favorable illumination (low phase angle) of the atmosphere as seen from the Cassini spacecraft. Other observations also show the same feature.

Dinelli, B. M.; Adriani, A.; Lopez-Puertas, M.; Moriconi, M. L.; Garcia-Comas, M.; Coradini, A.; D'Aversa, E.; Filacchione, G.; Tosi, F.

2009-04-01

57

Anomalous hydrogen emissions from the San Andreas fault observed at the Cienega Winery, central California  

Microsoft Academic Search

We began continuous monitoring of H2 concentration in soil along the San Andreas and Calaveras faults in central California in December 1980, using small H2\\/O2 fuel-cell sensors. Ten monitoring stations deployed to date have shown that anomalous H2 emissions take place occasionally in addition to diurnal changes. Among the ten sites, the Cienega Winery site has produced data that are

Motoaki Sato; A. J. Sutton; K. A. McGee

1984-01-01

58

Discovery of Radio Emission From Transient Anomalous X-Ray Pulsar XTE J1810-197  

Microsoft Academic Search

We report the first detection of radio emission from any anomalous X-ray pulsar (AXP). Data from the Very Large Array (VLA) MAGPIS survey with angular resolution 6'' reveals a point-source of flux density 4.5 {+-} 0.5 mJy at 1.4 GHz at the precise location of the 5.54 s pulsar XTE J1810-197. This is greater than upper limits from all other

J. P. Halpern; E. V. Gotthelf; R. H. Becker; D. J. Helfand; R. L. White

2005-01-01

59

Subsurface emission effects in AMSR-E measurements: Implications for land surface microwave emissivity retrieval  

NASA Astrophysics Data System (ADS)

An analysis of land surface microwave emission time series shows that the characteristic diurnal signatures associated with subsurface emission in sandy deserts carry over to arid and semiarid regions worldwide. Prior work found that diurnal variation of Special Sensor Microwave/Imager (SSM/I) brightness temperatures in deserts was small relative to International Satellite Cloud Climatology Project land surface temperature (LST) variation and that the difference varied with surface type and was largest in sand sea regions. Here we find more widespread subsurface emission effects in Advanced Microwave Scanning Radiometer-EOS (AMSR-E) measurements. The AMSR-E orbit has equator crossing times near 01:30 and 13:30 local time, resulting in sampling when near-surface temperature gradients are likely to be large and amplifying the influence of emission depth on effective emitting temperature relative to other factors. AMSR-E measurements are also temporally coincident with Moderate Resolution Imaging Spectroradiometer (MODIS) LST measurements, eliminating time lag as a source of LST uncertainty and reducing LST errors due to undetected clouds. This paper presents monthly global emissivity and emission depth index retrievals for 2003 at 11, 19, 37, and 89 GHz from AMSR-E, MODIS, and SSM/I time series data. Retrieval model fit error, stability, self-consistency, and land surface modeling results provide evidence for the validity of the subsurface emission hypothesis and the retrieval approach. An analysis of emission depth index, emissivity, precipitation, and vegetation index seasonal trends in northern and southern Africa suggests that changes in the emission depth index may be tied to changes in land surface moisture and vegetation conditions.

Galantowicz, John F.; Moncet, Jean-Luc; Liang, Pan; Lipton, Alan E.; Uymin, Gennady; Prigent, Catherine; Grassotti, Christopher

2011-09-01

60

Spontaneous coherent microwave emission and the sawtooth instability in a compact storage ring  

Microsoft Academic Search

Strong evidence for self-excited emission of coherent synchrotron radiation in the microwave spectral region was observed at the Synchrotron Ultraviolet Radiation Facility (SURF III) electron storage ring at the NIST. The microwave emission between 25 and 35 mm was dominated by intense bursts of radiation. The intensity enhancement during these bursts was on the order of 10 000 to 50

U. Arp; G. T. Fraser; A. R. Hight Walker; T. B. Lucatorto; K. K. Lehmann; K. Harkay; N. Sereno; K.-J. Kim

2001-01-01

61

The Effect of Intercepted Precipitation on the Microwave Emission of Maize at 1.4 GHz  

Technology Transfer Automated Retrieval System (TEKTRAN)

Terrestrial microwave emission is sensitive to soil moisture. Soil moisture is an important yet unobserved reservoir of the hydrologic cycle linked to precipitation variability. Remote sensing satellites that observe terrestrial microwave emission have the potential to map the spatial and temporal...

62

Anomalous Emissions of Sulfur Dioxide and Seismicity of San Miguel Volcano, EL Salvador in October, 2006  

NASA Astrophysics Data System (ADS)

San Miguel (also known as Chaparrastique) volcano in eastern El Salvador is located 15 km southwest of the city of San Miguel. This volcano has erupted more than 30 times since 1699, with the last gas and ash emission on January 16, 2002. During 2006, San Miguel presented anomalous gas emissions and seismicity. In this work, the seismic parameters reported by SNET (Servicio Nacional de Estudios Territoriales de El Salvador) and the crater gas emissions measured by researchers of the University of El Salvador are compared. For the gas efflux, two types of measurements were done using the Mini-DOAS system (Galle et al., 2002): transects around the crater perimeter (~100 m) and transects following roads located between 5 and 10 km from the crater. Several measurements between October 2005 and May 2006 indicate that the sulfur dioxide efflux during quiet periods is around 20 ton/day. From May to June 2006, a progressive increase in fumarolic activity and noise from gas emissions were observed. From May to August 2006, the sulfur dioxide emissions increased to 60 ton/day. A seismic crisis started on October 9, 2006, increasing the RSAM from 10-20 to 208 on October 10, 2006. During this time, the sulfur dioxide efflux reached a maximum of 492 ton/day. This increase in sulfur dioxide efflux represents 25 times the basic emissions during the previous quiet period and 8 times the values observed from May to August 2006. The correlation coefficient between sulfur dioxide efflux and RSAM values during this period of time was 0.81, which is statistically significant at a level higher than 99.9% . These anomalous changes in seismicity and sulfur dioxide emissions at San Miguel volcano suggest a magmatic reactivation with an increase in the exsolution of magma volatiles, long period seismic events, and volcanic tremor.

Olmos, R.; Barahona, F.; Hernández, A.; Cartagena, R.; Henríquez, B.; López, D.; Cárdenas, C.; Galle, B.

2007-12-01

63

Vacuum Microelectronic Field Emission Array Devices for Microwave Amplification.  

NASA Astrophysics Data System (ADS)

This dissertation presents the design, analysis, and measurement of vacuum microelectronic devices which use field emission to extract an electron current from arrays of silicon cones. The arrays of regularly-spaced silicon cones, the field emission cathodes or emitters, are fabricated with an integrated gate electrode which controls the electric field at the tip of the cone, and thus the electron current. An anode or collector electrode is placed above the array to collect the emission current. These arrays, which are fabricated in a standard silicon processing facility, are developed for use as high power microwave amplifiers. Field emission has been studied extensively since it was first characterized in 1928, however due to the large electric fields required practical field emission devices are difficult to make. With the development of the semiconductor industry came the development of fabrication equipment and techniques which allow for the manufacture of the precision micron-scale structures necessary for practical field emission devices. The active region of a field emission device is a vacuum, therefore the electron travel is ballistic. This analysis of field emission devices includes electric field and electron emission modeling, development of a device equivalent circuit, analysis of the parameters in the equivalent circuit, and device testing. Variations in device structure are taken into account using a statistical model based upon device measurements. Measurements of silicon field emitter arrays at DC and RF are presented and analyzed. In this dissertation, the equivalent circuit is developed from the analysis of the device structure. The circuit parameters are calculated from geometrical considerations and material properties, or are determined from device measurements. It is necessary to include the emitter resistance in the equivalent circuit model since relatively high resistivity silicon wafers are used. As is demonstrated, the circuit model accurately predicts the magnitude of the emission current at a number of typical bias current levels when the device is operating at frequencies within the range of 10 MHz to 1 GHz. At low frequencies and at high frequencies within this range, certain parameters are negligible, and simplifications may be made in the equivalent circuit model.

Mancusi, Joseph Edward

64

An anomalous component of Neptune radio emission - Implications for the auroral zone  

NASA Astrophysics Data System (ADS)

The Voyager planetary radio astronomy experiment detected a bursty, narrow-band radio emission originating in Neptune's magnetosphere. The time of occurrence of nearly all of the episodes of this bursty radio emission can be explained on the basis of a radio source located just above and to the east of the south magnetic offset tilted dipole (OTD) tip (Farrell et al., 1990). However, several episodes of bursty emission do not occur at the usual frequency and planetaray rotation phase for emissions of this type. The occurrences of these rarely seen anomalous episodes are shifted systematically in planetary longitude so as to be consistent with a source of emission to the southwest of the southern magnetic OTD pole. Owing to the proximity of these sources to the magnetic polar region, they are associated with an active auroral region. Therefore, at least from the standpoint of the radio emission, the picture that emerges is of an auroral zone with two emission hot spots approximately diametrically east and west of the south magnetic pole. The possibility of a complete radio-active auroral oval is discussed.

Desch, M. D.; Farrell, W. M.; Kaiser, M. L.

1991-02-01

65

Relationship of solar gamma ray emissions with microwaves and other radio bursts  

Microsoft Academic Search

The relationships of solar gamma ray (GR) emissions with microwave (MW) and other radio bursts have been studied. The GR emissions are found to start about 1-2 min after the onset of MW emissions (on 17 GHz) or about 0.5 min before the peak of MW emissions. This time delay may be due to differences in acceleration times for accelerating

V. K. Verma

1987-01-01

66

Anomalous photoconductivity decay observed in microwave measurements of carrier lifetime in silicon ingots  

Microsoft Academic Search

A brief description is given of a microwave noncontact method for measuring excess-carrier lifetime in which a base of the\\u000a ingot under investigation is selected for pulsed illumination. The method is employed in an experiment on silicon ingots placed\\u000a between an emitting and a receiving waveguide, with the illumination provided by a 1.06-?m semiconductor laser. With an illuminated\\u000a area of

P. A. Borodovskii; A. F. Buldygin; A. S. Tokarev

2006-01-01

67

Frequency agile microwave photonic notch filter with anomalously high stopband rejection.  

PubMed

We report a novel class microwave photonic (MWP) notch filter with a very narrow isolation bandwidth (10 MHz), an ultrahigh stopband rejection (>60??dB), a wide frequency tuning (1-30 GHz), and flexible bandwidth reconfigurability (10-65 MHz). This performance is enabled by a new concept of sideband amplitude and phase controls using an electro-optic modulator and an optical filter. This concept enables energy efficient operation in active MWP notch filters, and opens up a pathway toward enabling low-power nanophotonic devices as high-performance RF filters. PMID:24177078

Marpaung, David; Morrison, Blair; Pant, Ravi; Eggleton, Benjamin J

2013-11-01

68

Anomalous secondary electron emission of metallic surfaces exposed to a Glow Discharge plasma  

NASA Astrophysics Data System (ADS)

Secondary electron emission (SEE) yields, ?, of Li, stainless steel (SS) and W surfaces immersed in a He Direct Current Glow Discharge (dc-GD) Plasma have been calculated from the experimental I-V curves as a function of electron mean energy. The data obtained showed that ?Li > ?SS > ?W. Line emission ratios 728/706 of excited He and Langmuir probe measurements provide a clear evidence of the presence of a suprathermal electron tail responsible for the observed SEE.The results show that SEE is well correlated with the anomalous extra current component found in the I-V curves. The resulting value of ?Li is significantly higher than its theoretical value suggesting a possible synergetic effect of the ion bombardment in the SEE of lithium. The effect of Li surface oxidation has also been addressed, leading to a substantial decrease of both, sputtering yield and SEE yield of Li with higher oxygen content.

Oyarzabal, E.; Martín-Rojo, A. B.; Ferreira, J. A.; Tafalla, D.; Tabarés, F. L.

2013-07-01

69

Benchmarking of L-band soil microwave emission models  

NASA Astrophysics Data System (ADS)

A first step before assimilating Soil Moisture and ocean Salinity (SMOS) L-band brightness temperatures (Tb) over land is to couple land surface models (LSM) to microwave emission models. In this study, the ISBA LSM is coupled to the Community Microwave Emission Model (CMEM). Simulations of Tb are performed over a 3-yr period (2003-2005) for a bare soil field in southwestern France, at the SMOSREX experimental site. Both ISBA and CMEM present several options for the representation of the soil moisture and soil temperature profiles. Simplified 2-layer simulations are compared with more detailed multilayer simulations. In the 2-layer simulations, the soil is divided in two layers (a thin surface layer and a bulk reservoir), and Fresnel laws are used in CMEM to model the smooth surface emissivity. In the multilayer simulations, the ISBA soil diffusion scheme is used (with 11 soil layers represented) together with the Wilheit (1978) option of CMEM. The Tb simulations are compared to the Tb ground observations available for the SMOSREX site, at H and V polarizations and at different angles and the impact of soil roughness is assessed. It is shown that Tb values derived from the more complex multilayer simulations correlate better to the observations than Tb derived from the 2-layer model. This is partly due to a better representation of the soil moisture profile. However, taking surface soil moisture into account in the calculation of soil roughness is needed to represent the seasonal trend of Tb produced by the multilayer model. Finally, the multilayer model is used to investigate the L-band sampling depth for contrasting soil texture profiles. For the SMOSREX soil texture, it is found that Tb is mainly driven by the top 15 cm soil layer. However, from May to October, a significant part of the signal originates from deeper soil layers, and an accuracy of ±0.1 K can be achieved by representing a multilayer soil profile from the surface to a depth of 35 cm.

Calvet, Jean-Christophe; Parrens, Marie; de Rosnay, Patricia; Decharme, Bertrand

2013-04-01

70

MICROWAVE POPCORN EMISSIONS RELEASED DURING COOKING AND BAG OPENING  

EPA Science Inventory

Data are not currently available on the contaminants released when microwave popcorn, flavorings and bags are heated to microwave temperatures. Thus, the primary goal of this work is to identify and quantify contaminants emitted while popping and opening a bag of microwave popcor...

71

Studying the Polarization Characteristics of Thermal Microwave Emission from a Cloudy Atmosphere  

Microsoft Academic Search

We present the results of spectral studies of thermal microwave emission from a cloudy atmosphere at 37 and 85 GHz. The experimental data are interpreted on the basis of modeling of microwave radiation transfer in the mixed-type clouds containing ice crystals of different shapes and supercooled water drops. All orders of scattering are taken into account. It is shown that polarization

A. V. Troitsky; A. M. Osharin; A. V. Korolev; W. Strapp; G. Isaak

2001-01-01

72

Frequency and angular variations of land surface microwave emissivities: can we estimate SSM\\/T and AMSU emissivities from SSM\\/I emissivities?  

Microsoft Academic Search

To retrieve temperature and humidity profiles from special sensor microwave\\/temperature (SSM\\/T) and advanced microwave sounding units (AMSU), it is important to quantify the contribution of the Earth surface emission. So far, no global estimates of the land surface emissivities are available at SSM\\/T and AMSU frequencies and scanning conditions. The land surface emissivities have been previously calculated for the globe

Catherine Prigent; Jean-Pierre Wigneron; William B. Rossow; Juan R. Pardo-Carrion

2000-01-01

73

Microwave backscattering and emission model for grass canopies  

SciTech Connect

Microwave radar and radiometer measurements of grasslands indicate a substantial reduction in sensor sensitivity to soil moisture in the presence of a thatch layer. When this layer is wet it masks changes in the underlying soil, making the canopy appear warm in the case of passive sensors (radiometer) and decreasing backscatter in the active case (scatterometer). A model for a grass canopy with thatch will be presented in this paper to explain this behavior and to compare with observations. The canopy model consists of three layers: grass, thatch, and the underlying soil. The grass blades are modeled by elongated elliptical discs and the thatch is modeled as a collection of disk shaped water droplets (i.e., the dry matter is neglected). The ground is homogeneous and flat. The distorted Born approximation is used to compute the radar cross section of this three layer canopy and the emissivity is computed from the radar cross section using the Peake formulation for the passive problem. Results are computed at L-band (1.4 GHz) and C-band (4.75 GHz) using canopy parameters (i.e., plant geometry, soil moisture, plant moisture, etc.) representative of Konza Prairie grasslands. The results are compared to C-band scatterometer measurements and L-band radiometer measurements at these grasslands.

Saatchi, S.S. (Jet Propulsion Lab., Pasadena, CA (United States)); Le Vine, D.M. (National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center); Lang, R.H. (George Washington Univ., Washington, DC (United States). Dept. of Electrical and Computer Engineering)

1994-01-01

74

Characterization of Different Land Classes and Disaster Monitoring Using Microwave Land Emissivity for the Indian Subcontinent  

NASA Astrophysics Data System (ADS)

Despite the ability of satellite borne microwave radiometers to measure the atmospheric pa-rameters, liquid water and the microphysical properties of clouds, they have serious limitations over the land owing its large and spatially heterogeneous emissivity compared to the relatively low and homogenous oceans. This calls for determination of the spatial maps of land-surface emissivity with accuracies better than ˜2%. In this study, the characterization of microwave emissivity of different land surface classes over the Indian region is carried out with the forth-coming Indo-French microwave satellite program Megha-Tropiques in focus. The land emissivity is retrieved using satellite microwave radiometer data from Special Sensor Microwave/Imager (SSM/I) and TRMM Microwave Imager (TMI) at 10, 19, 22, 37 and 85 GHz. After identify-ing the clear sky daily data, the microwave radiative transfer computation, is applied to the respective daily atmospheric profile for deducing the upwelling and downwelling atmospheric radiations. This, along with the skin temperature data, is used to retrieve land emission from satellites data. The emissivity maps of placecountry-regionIndia for three months representing winter (January) and post-monsoon (September-October) seasons of 2008 at V and H polar-izations of all the channels (except for 22 GHz) are generated. Though the land emissivity values in V-polarization vary between 0.5 and ˜1, some land surface classes such as the desert region, marshy land, fresh snow covered region and evergreen forest region, etc, show distinct emissivity characteristics. On this basis few typical classes having uniform physical properties over sufficient area are identified. Usually the Indian desert region is dry and shows low emis-sivity (˜0.88 in H-polarisation) and high polarization difference, V-H (˜0.1). Densely vegetated zones of tropical rain forests exhibit high emissivity values (˜0.95) and low polarization dif-ference (lt;0.01). The mangrove forest region and marshy areas exhibit very low emissivities (˜0.8) with very high polarization difference (˜0.2). The usefulness of microwave emissivity to identify and quantify natural disasters such as the inundated regions in the vast Ganga basin during the severe floods in 2008 over country-regionIndia and placecountry-regionBangladesh is also demonstrated as a case study Keywords: Land surface emissivity, Microwave Remote sensing, Megha-Tropiques, Disaster monitoring *corresponding author: koraksaha@gmail.com

Saha, Korak; Raju, Suresh; Antony, Tinu; Krishna Moorthy, K.

75

Development of an improved microwave ocean surface emissivity radiative transfer model  

NASA Astrophysics Data System (ADS)

An electromagnetic model is developed for predicting the microwave blackbody emission from the ocean surface over a wide range of frequencies, incidence angles, and wind vector (speed and direction) for both horizontal and vertical polarizations. This ocean surface emissivity model is intended to be incorporated into an oceanic radiative transfer model to be used for microwave radiometric applications including geophysical retrievals over oceans. The model development is based on a collection of published ocean emissivity measurements obtained from satellites, aircraft, field experiments, and laboratory measurements. This dissertation presents the details of methods used in the ocean surface emissivity model development and comparisons with current emissivity models and aircraft radiometric measurements in hurricanes. Especially, this empirically derived ocean emissivity model relates changes in vertical and horizontal polarized ocean microwave brightness temperature measurements over a wide range of observation frequencies and incidence angles to physical roughness changes in the ocean surface, which are the result of the air/sea interaction with surface winds. Of primary importance are the Stepped Frequency Microwave Radiometer (SFMR) brightness temperature measurements from hurricane flights and independent measurements of surface wind speed that are used to define empirical relationships between C-band (4--7 GHz) microwave brightness temperature and surface wind speed. By employing statistical regression techniques, we develop a physical-based ocean emissivity model with empirical coefficients that depends on geophysical parameters, such as wind speed, wind direction, sea surface temperature, and observational parameters, such as electromagnetic frequency, electromagnetic polarization, and incidence angle.

El-Nimri, Salem Fawwaz

76

A noncontact method for detecting acoustic emission using a microwave Doppler radar motion detector.  

PubMed

A noncontact method for detecting acoustic emission was developed, using a microwave Doppler radar detector and an active band-pass filter. A theoretical model was developed and a prototype sensor was built and tested. The prototype responds to acoustic emissions (AE), from pencil lead break tests, at ranges up to 1.5 feet. PMID:16285461

Smith, Gregory C

2005-09-01

77

A new radiation balance microwave thermograph for simultaneous and independent temperature and emissivity measurements.  

PubMed

In the past, biomedical temperature measurements by microwave radiometry suffered from variable mismatch (emissivity less than 1) between the specimen under test and the receiving antenna. We have developed an improved radiometer, which simultaneously measures temperature and emissivity, independent by of a possible mismatch. Comparative measurements demonstrate the superiority of the new system as compared to conventional ones. PMID:259079

Luedeke, K M; Koehler, J; Kanzenbach, J

1979-06-01

78

Two-dimensional imaging of optical emission in a multicusp-ECR microwave resonant cavity  

SciTech Connect

Optical emission of the electron-cyclotron resonant (ECR) region of a multicusp microwave resonant cavity plasma source has been imaged onto a two-dimensional charge-coupled device (CCD) camera. The technique provides a real-time diagnostic of the plasma emission around the ECR region within a wavelength region defined by low-bandpass filters.

Brooks, C.B.; Brake, M.L. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering

1996-02-01

79

Coronal Heating and Microwave Emission from the Solar Active Region NOAA 0139  

NASA Astrophysics Data System (ADS)

Dynamics and structure of the active region NOAA 0139 on the basis of microwave observations at RT-22, SSRT, and RATAN-600 have been investigated. As appears from the wavelet analysis the observed behavior of the S-component of microwave emission is determined by elementary flare events. It has been shown that accelerated electrons can play an important role in heating the plasma of the transition region and upper chromosphere.

Tsap, Y. T.; Tsvetkov, L. I.; Yurovsky, Y. F.; Peterova, N. G.; Borisevich, T. B.; Agalakov, B. V.

2006-08-01

80

Impulsive microwave burst and solar noise storm emission resolved with the VLA  

Microsoft Academic Search

The evolution of a microwave burst at 20.7 cm wavelength and a type I noise storm at 91.6 cm wavelength are examined using VLA. The magnetic loops in the two spectral regions are studied. The sizes and brightness temperatures of the 20.7 cm burst sources are compared with those predicted by multithermal and nonthermal models of microwave burst emission of

Robert F. Willson; Kenneth R. Lang; Margaret Liggett

1990-01-01

81

Soil moisture and temperature profile effects on microwave emission at low frequencies  

Microsoft Academic Search

Soil moisture and temperature vertical profiles vary quickly during the day and may have a significant influence on the soil microwave emission. The objective of this work is to quantify such an influence and the consequences in soil moisture estimation from microwave radiometric information. The analysis is based on experimental data collected by the ground-based PORTOS radiometer at 1.4, 5.05,

Suresh Raju; André Chanzy; Jean-Pierre Wigneron; Jean-Christophe Calvet; Yann Kerr; Laurent Laguerre

1995-01-01

82

Detection of microwave emission from solid targets ablated with an ultrashort pulsed laser  

NASA Astrophysics Data System (ADS)

In addition to visible and near-IR emission, recent investigations have shown that electromagnetic pulses (EMP) in the microwave and RF regions of the spectrum are generated during femtosecond laser-matter interactions if the laser source is sufficiently intense to ablate and ionize an illuminated solid target material. Although the mechanisms for the laserinduced EMP pulse are not fully characterized, it is reported that this phenomenon arises from two mechanisms associated with terawatt to petawatt level laser interactions with matter: (1) ionization via propagation in air, and (2) plasma generation associated with the laser-excited solid material. Over the past year, our group has examined the microwave emission profiles from a variety of femtosecond laser ablated materials, including metals, semiconductors, and dielectrics. We have directed our measurements towards the characterization of microwave emission from ablated surfaces in air using laser peak powers in excess of 1012 Watts (energy/pulse ~50 mJ, pulse width ~30 fs, laser diameter at target ~200 microns). We have characterized the temporal profile of the microwave emission and determined the emission from all samples is omni-directional. We have also observed a difference in the minimum fluence required to generate emission from conducting and insulating materials although the peak amplitudes from these materials were quite similar at the upper laser energy levels of our system (~50 mJ).

Miragliotta, Joseph A.; Brawley, Benjamin; Sailor, Caroline; Spicer, James B.; Spicer, Jane W. M.

2011-05-01

83

Cosmic-ray Observation via Microwave Emission (CROME)  

NASA Astrophysics Data System (ADS)

The CROME experiment has been designed for a measurement of microwave signals emitted by extensive air showers. It has been fully operational since May 2011 in cooperation with the KASCADE-Grande experiment. A signal in the extended C band range (3.4-4.2GHz) is read out for every trigger provided by KASCADE-Grande. Due to the air shower reconstruction by KASCADE-Grande we could analyse all events crossing the field of view of the CROME antennas. Clear microwave signal was measured for twenty cosmic ray showers over one year of measurement. The detector setup and its performance are described in this proceeding. We provide details also about test and calibration measurements, which have provided a detailed knowledge of our detector. We conclude by showing microwave pulses measured by CROME for extensive air showers above 1016.5 eV.

Šmída, R.; Bertaina, M.; Blümer, J.; Chiavassa, A.; Cossavella, F.; Di Pierro, F.; Engel, R.; Haungs, A.; Huege, T.; Kampert, K.-H.; Klages, H.; Kleifges, M.; Krömer, O.; Ludwig, M.; Mathys, S.; Neunteufel, P.; Pekala, J.; Rautenberg, J.; Riegel, M.; Roth, M.; Salamida, F.; Schieler, H.; Stasielak, J.; Unger, M.; Weber, M.; Werner, F.; Wilczy?ski, H.; Will, M.; Wochele, J.

2013-05-01

84

Anomalous hydrogen emissions from the San Andreas fault observed at the Cienega Winery, central California  

NASA Astrophysics Data System (ADS)

We began continuous monitoring of H2 concentration in soil along the San Andreas and Calaveras faults in central California in December 1980, using small H2/O2 fuel-cell sensors. Ten monitoring stations deployed to date have shown that anomalous H2 emissions take place occasionally in addition to diurnal changes. Among the ten sites, the Cienega Winery site has produced data that are characterized by very small diurnal changes, a stable baseline, and remarkably distinct spike-like H2 anomalies since its installation in July 1982. A major peak appeared on 1 10 November 1982, and another on 3 April 1983, and a medium peak on 1 November 1983. The occurrences of these peaks coincided with periods of very low seismicity within a radius of 50 km from the site. In order to methodically assess how these peaks are related to earthquakes, three H2 degassing models were examined. A plausible correlational pattern was obtained by using a model that (1) adopts a hemicircular spreading pattern of H2 along an incipient fracture plane from the hypocenter of an earthquake, (2) relies on the FeO-H2O reaction for H2 generation, and (3) relates the accumulated amount of H2 to the mass of serpentinization of underlying ophiolitic rocks; the mass was tentatively assumed to be proportional to the seismic energy of the earthquake.

Sato, Motoaki; Sutton, A. J.; McGee, K. A.

1984-03-01

85

Anomalous off-axis emissions on the resonance strontium line, illuminated by a quasi-resonant pulsed laser light  

Microsoft Academic Search

When the lambda = 460.7 nm strontium line is excited by a non-exactly resonant pulsed laser light, one observes anomalous off-axis emissions in the forward scattered light. At a moderate laser flux density (less than 1 MW\\/cm2) a conical frequency-shifted fluorescence occurs for a blue laser detuning. This is explained in term of coupling between the laser field and the

G. Brechignac; Ph. Cahuzac; A. Debarre

1980-01-01

86

Microwave emission from an AXIAL-Virtual Cathode Oscillator driven by a compact pulsed power source  

NASA Astrophysics Data System (ADS)

For the generation of microwaves, Electron beam devices operating in vacuum are most widely used. For pulsed and high power microwave generation, Virtual cathode oscillators (VIRCATORs) are said to be simple in operation and construction. They are generally driven by a pulsed power source which gives high input powers to the Vircator connected as load. Vircator, depending upon its efficiency, converts the electrical input power to the microwave power. We are presenting the results of an axial Vircator operating in 2×10-4 mbar vacuum and is driven by a compact pulsed power source. The energy source and pulse compression is realized in very user friendly approach to run the system. The radiating system presently runs at relatively low powers but has the scope of reaching to high power by a logical improvement. A study of effect of collapsing diode impedance, of the vacuum field emission diode of the Vircator, on the microwave emission is presented in the paper. We are also presenting the microwave emission measurement conducted in the given system. Effect of vacuum is also studied to the extent of present experimental limits.

Shukla, R.; Sharma, S. K.; Banerjee, P.; Deb, P.; Prabaharan, T.; Das, R.; Kdas, B.; Adhikary, B.; Verma, R.; Shyam, A.

2012-11-01

87

Microwave emission due to hypervelocity impacts and its correlation with mechanical destruction  

NASA Astrophysics Data System (ADS)

Microwave emission due to hypervelocity impacts on metallic plates has been found. The targets used in the experiment are aluminum plates with various thicknesses. The projectile, a nylon cylinder with metal screw of 0.21 gm, was accelerated up to the velocity of 4 km/s; a heterodyne receiver detected the microwave at 22 GHz. The emission is a random sequence of pulses with several nanosecond width, which lasts more than 10 mus. The phenomenon seems to be dependent on the extent of target destruction through the formation of impact craters or penetration. If so, we could use the characteristics of the phenomena to better understand the mechanical destruction process. We propose several models for the cause of this microwave generation and study them on the basis of timing relation of observed events.

Takano, T.; Murotani, Y.; Maki, K.; Toda, T.; Fujiwara, A.; Hasegawa, S.; Yamori, A.; Yano, H.

2002-11-01

88

Topographic Effects on the Surface Emissivity of a Mountainous Area Observed by a Spaceborne Microwave Radiometer  

Microsoft Academic Search

A simulation study to understand the influence of topography on the surface emissivity observed by a satellite microwave radiometer is carried out. We analyze the effects due to changes in observation angle, including the rotation of the polarization plane. A mountainous area in the Alps (Northern Italy) is considered and the information on the relief extracted from a digital elevation

Luca Pulvirenti; Nazzareno Pierdicca; Frank S. Marzano

2008-01-01

89

Regionalization of Methane Emissions in the Amazon Basin with Multi-temporal Microwave Remote Sensing  

Microsoft Academic Search

Remote sensing of the Amazon basin with passive and active microwave techniques were applied to determine the temporally varying extent of inundation and associated vegetation, and used in conjunction with field measurements to calculate regional rates of methane emission from wetlands to the atmosphere. Monthly inundation areas were derived from analysis of the 37-GHz polarization difference observed by the Scanning

J. M. Melack; L. L. Hess; B. R. Forsberg; S. K. Hamilton; E. M. Novo

2002-01-01

90

Sensitivities of an atmospheric profiling retrieval to the microwave land emissivity  

Microsoft Academic Search

This study focuses on microwave land surface emissivity estimation over Northern Africa and the Middle East and the related impact on temperature and moisture retrievals. Land surface temperature retrievals are performed using a plane-parallel radiative transfer model, analyses from the Navy Operational Global Atmospheric Prediction System (NOGAPS) and data from the High Resolution Infrared Radiation Sounder Version 3 (HIRS\\/3). Infrared

Benjamin Ruston; Nancy L. Baker

2004-01-01

91

Diacetyl Emissions and Airborne Dust from Butter Flavorings Used in Microwave Popcorn Production  

Microsoft Academic Search

In microwave popcorn workers, exposure to butter flavorings has been associated with fixed obstructive lung disease resembling bronchiolitis obliterans. Inhalation toxicology studies have shown severe respiratory effects in rats exposed to vapors from a paste butter flavoring, and to diacetyl, a diketone found in most butter flavorings. To gain a better understanding of worker exposures, we assessed diacetyl emissions and

Randy Boylstein; Chris Piacitelli; Ardith Grote; Richard Kanwal; Greg Kullman; Kathleen Kreiss

2006-01-01

92

The role of snow on microwave emission and scattering over first-year sea ice  

Microsoft Academic Search

Investigates the geophysical and thermodynamic effects of snow on sea ice in defining the electromagnetic (EM) interaction within the microwave portion of the spectrum. The authors combine observational evidence of both the physical and thermodynamic characteristics of snow with direct measurements of scattering and emission at a variety of frequencies. They explain their observational results using various “state-of-the-art” forward scattering

David G. Barber; A. K. Fung; Thomas C. Grenfell; Son V. Nghiem; Robert G. Onstott; V. I. Lytle; Donald K. Perovich; Anthony J. Gow

1998-01-01

93

Microwave Magnetic Field Imaging Using Thermo-Emissive Ferromagnetic Micro-Structured Films  

Microsoft Academic Search

A new microwave magnetic field measurement method based on infrared emission is presented. This method uses thin patterned ferromagnetic films sputtered on polymer substrates. The incident field interacts with the film and is responsible for ferromagnetic losses that create local heating. This heating is recorded by an infrared camera, providing magnetic field pattern images and amplitude evaluation. Moreover, the tangential

J. Vernieres; J. F. Bobo; D. Prost; F. Issac; F. Boust

2011-01-01

94

Seasonal characterization of microwave emissions from snow-covered first-year sea ice  

Microsoft Academic Search

Brightness temperature TB data were collected with a surface-based radiometer operating on both vertical and horizontal polarizations at frequencies of 19, 37, and 85 GHz. Both microwave emissions and thermophysical data were collected as part of the Collaborative-Interdisciplinary Cryospheric Experiment between 15 May and 25 June 2000, in the Canadian High Arctic. Each season was characterized by a running variance

Isabelle P.-F. Harouche; David G. Barber

2001-01-01

95

Coherent population trapping in cesium: Dark lines and coherent microwave emission  

Microsoft Academic Search

The phenomenon of coherent population trapping in alkali-metal atoms is analyzed by means of a perturbation approach. Closed form transparent solutions are obtained for the coherences existing within the system and the populations of the ground levels and of the excited state. The presence of dark lines and coherent microwave emission from the ground state are made explicit. Experimental results

Jacques Vanier; Aldo Godone; Filippo Levi

1998-01-01

96

Measurements of emission levels during microwave and shortwave diathermy treatments  

SciTech Connect

Shortwave and microwave diathermy treatments are used to relieve pain through the noninvasive application of electromagnetic energy to body tissues. In administering these treatments, not all of the energy is confined to the treatment area. This stray radiation exposes unintended tissue of the patient and also can expose the operator (physical therapist, coach, and so forth). This study was conducted to quantify the exposure levels experienced by the operator during diathermy treatments. For the three microwave units surveyed, with the operator standing at the controls of the diathermy console, the maximum measured power density was 1.3 mW/cm/sup 2/ (equivalent to 70 V/m and 0.19 A/m in free space). For the six shortwave units surveyed, with the operator standing at the controls of the diathermy console, the maximum measured field strengths were 0.47 A/m and 250 V/m (equivalent to free-space power densities of 8.3 mw/cm/sup 2/ and 16.6 mW/cm/sup 2/). If the operator moved closer to the applicator during the treatment, the exposures would be much higher. This survey indicates a need for suppression of unnecessary radiation from the applicators of microwave diathermy units, and from the applicators and cables of shortwave diathermy units.

Ruggera, P.S.

1980-05-01

97

Land surface microwave emissivities derived from AMSR-E and MODIS measurements with advanced quality control  

NASA Astrophysics Data System (ADS)

A microwave emissivity database has been developed with data from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and with ancillary land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the same Aqua spacecraft. The primary intended application of the database is to provide surface emissivity constraints in atmospheric and surface property retrieval or assimilation. An additional application is to serve as a dynamic indicator of land surface properties relevant to climate change monitoring. The precision of the emissivity data is estimated to be significantly better than in prior databases from other sensors due to the precise collocation with high-quality MODIS LST data and due to the quality control features of our data analysis system. The accuracy of the emissivities in deserts and semiarid regions is enhanced by applying, in those regions, a version of the emissivity retrieval algorithm that accounts for the penetration of microwave radiation through dry soil with diurnally varying vertical temperature gradients. These results suggest that this penetration effect is more widespread and more significant to interpretation of passive microwave measurements than had been previously established. Emissivity coverage in areas where persistent cloudiness interferes with the availability of MODIS LST data is achieved using a classification-based method to spread emissivity data from less-cloudy areas that have similar microwave surface properties. Evaluations and analyses of the emissivity products over homogeneous snow-free areas are presented, including application to retrieval of soil temperature profiles. Spatial inhomogeneities are the largest in the vicinity of large water bodies due to the large water/land emissivity contrast and give rise to large apparent temporal variability in the retrieved emissivities when satellite footprint locations vary over time. This issue will be dealt with in the future by including a water fraction correction. Also note that current reliance on the MODIS day-night algorithm as a source of LST limits the coverage of the database in the Polar Regions. We will consider relaxing the current restrictions as part of future development.

Moncet, Jean-Luc; Liang, Pan; Galantowicz, John F.; Lipton, Alan E.; Uymin, Gennady; Prigent, Catherine; Grassotti, Christopher

2011-08-01

98

Possible manifestation of large-scale transverse oscillations of coronal loops in solar microwave emission  

NASA Astrophysics Data System (ADS)

Aims: We interpret long-periodic (minutes) modulations detected in solar microwave emission during flaring events as signatures of large-scale transverse oscillations of coronal loops. Methods: Our data analysis method is based methodologically on a sliding-window Fourier transform combined with the Vigner-Wille technique. We analyze three different events where TRACE detected post-flare oscillating loops (on Mar. 23, 2000; Sep. 15, 2001; Sep. 07, 2001) Results: For the transverse large-scale oscillatory motion of a loop, a properly located observer, in addition to the modulation caused by the emission diagram pattern motion at the main frequency of the loop oscillation, may detect a modulation at twice the frequency, produced by the varying magnetic field during each inclination of the loop. Our main result consists in identification of these “modulation pairs” in the dynamic spectra of solar microwave emission and their association with the observed oscillating coronal loops.

Khodachenko, M. L.; Kislyakova, K. G.; Zaqarashvili, T. V.; Kislyakov, A. G.; Panchenko, M.; Zaitsev, V. V.; Arkhypov, O. V.; Rucker, H. O.

2011-01-01

99

Diacetyl emissions and airborne dust from butter flavorings used in microwave popcorn production.  

PubMed

In microwave popcorn workers, exposure to butter flavorings has been associated with fixed obstructive lung disease resembling bronchiolitis obliterans. Inhalation toxicology studies have shown severe respiratory effects in rats exposed to vapors from a paste butter flavoring, and to diacetyl, a diketone found in most butter flavorings. To gain a better understanding of worker exposures, we assessed diacetyl emissions and airborne dust levels from butter flavorings used by several microwave popcorn manufacturing companies. We heated bulk samples of 40 different butter flavorings (liquids, pastes, and powders) to approximately 50 degrees C and used gas chromatography, with a mass selective detector, to measure the relative abundance of volatile organic compounds emitted. Air sampling was conducted for diacetyl and for total and respirable dust during the mixing of powder, liquid, or paste flavorings with heated soybean oil at a microwave popcorn plant. To further examine the potential for respiratory exposures to powders, we measured dust generated during different simulated methods of manual handling of several powder butter flavorings. Powder flavorings were found to give off much lower diacetyl emissions than pastes or liquids. The mean diacetyl emissions from liquids and pastes were 64 and 26 times larger, respectively, than the mean of diacetyl emissions from powders. The median diacetyl emissions from liquids and pastes were 364 and 72 times larger, respectively, than the median of diacetyl emissions from powders. Fourteen of 16 powders had diacetyl emissions that were lower than the diacetyl emissions from any liquid flavoring and from most paste flavorings. However, simulated handling of powder flavorings showed that a substantial amount of the airborne dust generated was of respirable size and could thus pose its own respiratory hazard. Companies that use butter flavorings should consider substituting flavorings with lower diacetyl emissions and the use of ventilation and enclosure engineering controls to minimize exposures. Until controls are fully implemented, companies should institute mandatory respiratory protection for all exposed workers. PMID:16998985

Boylstein, Randy; Piacitelli, Chris; Grote, Ardith; Kanwal, Richard; Kullman, Greg; Kreiss, Kathleen

2006-10-01

100

The MIDAS experiment: A prototype for the microwave emission of Ultra-High Energy Cosmic Rays  

NASA Astrophysics Data System (ADS)

Recent measurements suggest that extensive air showers initiated by ultra-high energy cosmic rays (UHECR) emit signals in the microwave band of the electromagnetic spectrum caused by the collisions of the free-electrons with the atmospheric neutral molecules in the plasma produced by the passage of the shower. Such emission is isotropic and could allow the detection of air showers with 100% duty cycle and a calorimetric-like energy measurement, a significant improvement over current detection techniques. We have built MIDAS (MIcrowave Detection of Air Showers), a prototype of microwave detector, which consists of a 4.5 m diameter antenna with a cluster of 53 feed-horns in the 4 GHz range. The details of the prototype and first results will be presented.

Monasor, M.; Alekotte, I.; Alvarez-Muñiz, J.; Berlin, A.; Bertou, X.; Bodgan, M.; Bohacova, M.; Bonifazi, C.; Carvalho, W.; de Mello Neto, J. R. T.; Genat, J. F.; Facal San Luis, P.; Mills, E.; Rouille D'Orfeuil, B.; Wayne, S.; Reyes, L. C.; Santos, E. M.; Privitera, P.; Williams, C.; Zas, E.

2011-06-01

101

MAGNETIC SUBSTRUCTURE IN THE NORTHERN FERMI BUBBLE REVEALED BY POLARIZED MICROWAVE EMISSION  

SciTech Connect

We report a correspondence between giant, polarized microwave structures emerging north from the Galactic plane near the Galactic center and a number of GeV gamma-ray features, including the eastern edge of the recently discovered northern Fermi Bubble. The polarized microwave features also correspond to structures seen in the all-sky 408 MHz total intensity data, including the Galactic center Spur. The magnetic field structure revealed by the Wilkinson Microwave Anisotropy Probe polarization data at 23 GHz suggests that neither the emission coincident with the Bubble edge nor the Galactic center Spur are likely to be features of the local interstellar medium. On the basis of the observed morphological correspondences, similar inferred spectra, and the similar energetics of all sources, we suggest a direct connection between the Galactic center Spur and the northern Fermi Bubble.

Jones, David I.; Crocker, Roland M.; Aharonian, Felix A. [Max-Planck-Institut fuer Kernphysik, Postfach 103980, 69029 Heidelberg (Germany); Reich, Wolfgang [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Ott, Juergen, E-mail: djones@mpi-hd.mpg.de [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville Road, Socorro, NM 87801 (United States)

2012-03-15

102

Effects of CsI Coating of Carbon Fiber Cathodes on the Microwave Emission From a Triode Virtual Cathode Oscillator  

Microsoft Academic Search

We discuss the effects of cesium iodide (CsI) coating of carbon fiber cathodes on the microwave emission from a triode virtual cathode oscillator. As compared with the uncoated cathode, the CsI-coated carbon fiber cathode significantly improved the diode performance and, most notably, lengthened the microwave pulse, from 150 to 200 ns. The light emission from the diode, the diode perveance,

Limin Li; Lie Liu; Jianchun Wen; Yonggui Liu

2009-01-01

103

Giant microwave bursts emitted from a field-emission, relativistic-electron-beam magnetron  

Microsoft Academic Search

A magnetron operating at a wavelength of 10 cm has been constructed with six resonant cavities cut in a cylindrical anode block. A graphite cylinder acting as a field-emission cathode delivers approx.12 kA in an accelerating radial potential of approx.360 kV. The magnetic field directed along the diode axis is approx.8 kG. Linearly polarized microwaves of 30 nsec duration at

G. Bekefi; T. J. Orzechowski

1976-01-01

104

Control of spin-wave emission from spin-torque nano-oscillators by microwave pumping  

Microsoft Academic Search

We demonstrate that microwave pumping of a spin-torque nano-oscillator can lead to transfer of the spin-wave energy generated by the oscillator into a mode with frequency given by the difference between the pumping frequency and that of the auto-oscillation. The decay length of spin waves at the combination frequency is significantly increased, while the directionality of emission is preserved. The

Vladislav E. Demidov; Sergei Urazhdin; Vasyl Tiberkevich; Andrei Slavin; Sergej O. Demokritov

2011-01-01

105

Microwave emission from plasmas produced by magnetically confined-electron beams  

Microsoft Academic Search

Microwave emission, in the x-band frequency range (8.2-12.4 GHz), from a thin, large, rectangular sheet plasma has been measured. The plasma electron density was such that the plasma frequency was within or just above this frequency range. The plasma was immersed in an external magnetic field from a set of Helmholz coils. The magnetic field was oriented parallel to the

Donald P. Murphy; Richard F. Fernsler; Robert E. Pechacek; Robert A. Meger

2002-01-01

106

Helium microwave induced plasma atomic emission detection for liquid chromatography utilizing a moving band interface  

Microsoft Academic Search

A moving band interface is used to separate HPLC solvent from analyte before introduction into a microwave-induced plasma atomic emission detector. Spectral scans indicate that all detectable solvent is removed prior to analyte introduction. Analyte memory effects are not detectable. Chlorine element selective detection limits are 140,410, 220, and 770 pg\\/s for 9-chlorofluorene, p-chlorobiphenyl, 4-chlorobenzophenone, and [alpha],[alpha]'-dichloro-o-xylene, respectively. If the

Peter B. Mason; Liming. Zhang; Jon W. Carnahan; Randall E. Winans

1993-01-01

107

Consideration of the mechanism of microwave emission due to material destruction  

NASA Astrophysics Data System (ADS)

Microwave emission due to material destruction by hypervelocity impact with several kilometers per second was found at 2 and 22 GHz, and its power was calibrated in the laboratory for the first time ever. In this paper, we first summarize the experimental results in relation to the mechanism of microwave emission. We then propose three kinds of hypotheses on the mechanism, which are based on the dynamic relative motion of an atom's nucleus and the outermost electron and lead to dipole radiation. The deduced equation represents the power dependence on the target's thickness, which agrees well with the experimental result. The models were then numerically analyzed in consideration of the experimental data. In the most promising model, a projectile molecule flicks the nucleus out and the outermost electron is left out of the orbit of the atom. Accordingly, the material is polarized or ionized to form an impulsive dipole, which leads to microwave emission. This model is compatible with material ionization by mechanical excitation, such as rubbing and peeling, or triboelectricity. The calculated energy shows good agreement with the experimental value. On the other hand, if the outermost electron remains within the gravity field of the nucleus, the calculated and experimental results do not agree with each other.

Takano, Tadashi; Ikeda, Hirokazu; Maeda, Takashi

2010-10-01

108

Excellent Field Emission Properties of Short Conical Carbon Nanotubes Prepared by Microwave Plasma Enhanced CVD Process  

NASA Astrophysics Data System (ADS)

Randomly oriented short and low density conical carbon nanotubes (CNTs) were prepared on Si substrates by tubular microwave plasma enhanced chemical vapor deposition process at relatively low temperature (350 550 °C) by judiciously controlling the microwave power and growth time in C2H2 + NH3 gas composition and Fe catalyst. Both length as well as density of the CNTs increased with increasing microwave power. CNTs consisted of regular conical compartments stacked in such a way that their outer diameter remained constant. Majority of the nanotubes had a sharp conical tip (5 20 nm) while its other side was either open or had a cone/pear-shaped catalyst particle. The CNTs were highly crystalline and had many open edges on the outer surface, particularly near the joints of the two compartments. These films showed excellent field emission characteristics. The best emission was observed for a medium density film with the lowest turn-on and threshold fields of 1.0 and 2.10 V/?m, respectively. It is suggested that not only CNT tip but open edges on the body also act as active emission sites in the randomly oriented geometry of such periodic structures.

Srivastava, Sanjay Kumar; Vankar, Vasant D.; Kumar, Vikram

2008-01-01

109

Emission of monochromatic microwave radiation from a nonequilibrium condensation of excited magnons  

NASA Astrophysics Data System (ADS)

The observation of monochromatic emission of radiation from a nonequilibrium Bose-Einstein-like condensate of magnons suggests the possibility of creating a monochromatic microwave generator pumped by incoherent broadband sources. The device would have a tunable emitted frequency as a function of the applied constant magnetic field. We present an analysis of the mechanisms of interaction between the condensate of magnons and the radiation field producing the super-radiant emission of photons. The conditions for the emergence of the super-radiance are described, as well as an analysis of its dependence on the thickness of the sample and the applied static magnetic field intensity.

Stucchi Vannucchi, Fabio; Rosas Vasconcellos, Áurea; Luzzi, Roberto

2013-08-01

110

Synthesis, field emission and microwave absorption of carbon nanotubes filled with ferromagnetic nanowires  

Microsoft Academic Search

Carbon nanotubes filled with ferromagnetic metal nanowires (M-CNTs) were synthesized by using chlorine-contained benzene (e.g.\\u000a trichlorobenzene) as precursor. The wall thicknesses of M-CNTs synthesized by trichlorobenzene are much thinner than those\\u000a by precursor without Cl (e.g. benzene). As-synthesized thin-walled M-CNTs exhibit remarkably enhanced field electron emission\\u000a performance with a low turn-on field of 0.3 V\\/?m and better field-emission stability. Microwave-absorption

RuiTao Lv; FeiYu Kang; JiaLin Gu; KunLin Wang; DeHai Wu

2010-01-01

111

Microwave remediation of emissions resulting from the treatment of electronic components  

SciTech Connect

The global community has become increasingly dependent on computer and other electronic technologies. As a result, society is faced with an increasing amount of obsolete equipment that is usually disposed of in landfills. While a convenient solution, this action causes a substantial loss of finite resources and poses a potential environmental threat as the various components breakdown and are exposed to the elements. Hazardous compounds such as lead, mercury, and cadmium may leach from the boards and find their way into the groundwater supply. In order to alleviate this potential problem, a microwave waste treatment system was developed that was capable of removing the organic compounds from the circuitry. Upon further heating in an industrial microwave, a glass and metal ingot were recovered. Analysis of the ingot revealed small concentrations of precious metals such as gold and silver. During treatment, gaseous organic and aromatic compounds were generated in the initial stages of processing. These emissions were successfully treated in a microwave off-gas system that reduced the concentration of the products emitted by several orders of magnitude and in some cases, completely destroyed components within the waste gas. In order to better understand the effects of processing parameters on the efficiency of the off-gas system, a parametric study was developed and undertaken. The study tested the microwave system at 3 incoming flow rates (10, 30, and 50 ft3/min) and 3 temperatures (400, 700, and 1000 degrees C). In order to determine the effects of microwave energy, some of the experiments were repeated using a conventional furnace in place of the microwave off-gas unit.

Schultz, R.L.

2000-04-25

112

VUV Emission Characteristics of High-Pressure Microgap Discharge Excited by Microwave  

NASA Astrophysics Data System (ADS)

It was shown that a stable atmospheric-pressure nonthermal air plasma could be produced at a high density (>10^15cm-3) in the microgap ( ˜ 100 ?m) between two knife edge electrodes by using microwave excitation [Jpn. J. Appl. Phys. 40 (2001) L238]. In the present work, Ar2 and Xe2 excimer emission characteristics of the microgap discharge were studied. The apparatus was installed in a pressure chamber and the total gas pressure was varied from 0.5 to 2.5 atm. Admixture of He with Ar or Xe was necessary to obtain a uniform discharge extending along the electrode length. The Ar2 emission ( ˜130 nm) or Xe2 emission ( ˜170 nm) dominated in the optical emission in the VUV region, but their intensities depended only weakly on the microwave power as well as on the total pressure. To understand the reasons for the results and to increase the VUV emission intensity, measurements of the gas temperature, electron temperature and electron density are in progress, as well as a modification of the apparatus for introducing gas flow through the microgap.

Kono, A.; Kano, T.; Sugiyama, T.

2002-10-01

113

Relative influence upon microwave emissivity of fine-scale stratigraphy, internal scattering, and dielectric properties  

USGS Publications Warehouse

The microwave emissivity of relatively low-loss media such as snow, ice, frozen ground, and lunar soil is strongly influenced by fine-scale layering and by internal scattering. Radiometric data, however, are commonly interpreted using a model of emission from a homogeneous, dielectric halfspace whose emissivity derives exclusively from dielectric properties. Conclusions based upon these simple interpretations can be erroneous. Examples are presented showing that the emission from fresh or hardpacked snow over either frozen or moist soil is governed dominantly by the size distribution of ice grains in the snowpack. Similarly, the thickness of seasonally frozen soil and the concentration of rock clasts in lunar soil noticeably affect, respectively, the emissivities of northern latitude soils in winter and of the lunar regolith. Petrophysical data accumulated in support of the geophysical interpretation of microwave data must include measurements of not only dielectric properties, but also of geometric factors such as finescale layering and size distributions of grains, inclusions, and voids. ?? 1976 Birkha??user Verlag.

England, A. W.

1976-01-01

114

Control of spontaneous emission from a microwave-field-coupled three-level{Lambda}-type atom in photonic crystals  

SciTech Connect

The spontaneous emission spectrum of a three-level {Lambda}-type atom driven by a microwave field was studied. For the two transitions coupled to the same modified reservoir, we discussed the influence of photonic band gap and Rabi frequency of the microwave field on the emission spectrum. The emission spectrum is given for different locations of the upper band-edge frequency. With the transition frequencies moving from outside the band gap to inside, the number of peaks decreases in the emission spectrum and the multipeak structure of spectral line is finally replaced by a strong non-Lorentzian shape. With increase of the Rabi frequency of the microwave field, we find the spectral line changes from a multipeak structure to a two-peak structure, originating from the inhibition of spontaneous emission for the corresponding decay channel.

Jiang, X. Q.; Zhang, B.; Sun, X. D. [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Lu, Z. W. [National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150001 (China)

2011-05-15

115

Topographic Effects on the Surface Emissivity of a Mountainous Area Observed by a Spaceborne Microwave Radiometer  

PubMed Central

A simulation study to understand the influence of topography on the surface emissivity observed by a satellite microwave radiometer is carried out. We analyze the effects due to changes in observation angle, including the rotation of the polarization plane. A mountainous area in the Alps (Northern Italy) is considered and the information on the relief extracted from a digital elevation model is exploited. The numerical simulation refers to a radiometric image, acquired by a conically-scanning radiometer similar to AMSR-E, i.e., flying at 705 km of altitude with an observation angle of 55°. To single out the impact on surface emissivity, scattering of the radiation due to the atmosphere or neighboring elevated surfaces is not considered. C and X bands, for which atmospheric effects are negligible, and Ka band are analyzed. The results indicate that the changes in the local observation angle tend to lower the apparent emissivity of a radiometric pixel with respect to the corresponding flat surface characteristics. The effect of the rotation of the polarization plane enlarges (vertical polarization), or attenuates (horizontal polarization) this decrease. By doing some simplifying assumptions for the radiometer antenna, the conclusion is that the microwave emissivity at vertical polarization is underestimated, whilst the opposite occurs for horizontal polarization, except for Ka band, for which both under- and overprediction may occur. A quantification of the differences with respect to a flat soil and an approximate evaluation of their impact on soil moisture retrieval are yielded.

Pulvirenti, Luca; Pierdicca, Nazzareno; Marzano, Frank S.

2008-01-01

116

Ultrahigh-energy pulsed emission from Hercules X-1 with anomalous air-shower muon production  

SciTech Connect

A search for bursts of air-shower events from Hercules X-1 at energies above 50 TeV during the calendar period 2 April 1986 to 5 July 1987 yielded two significant bursts, both occurring on UT 24 July 1986. The events during these bursts were pulsed with a period of 1.235 68 s, significantly different from estimates of the contemporaneous x-ray period. The probability that this represents random statistical fluctuations of the background is estimated to be 2 x 10/sup -5/. The muon content of the burst events is anomalous when compared with expectations from ..gamma..-ray showers.

Dingus, B.L.; Alexandreas, D.E.; Allen, R.C.; Burman, R.L.; Butterfield, K.B.; Cady, R.; Chang, C.Y.; Ellsworth, R.W.; Goodman, J.A.; Gupta, S.K.; and others

1988-10-24

117

Capacitively coupled microwave plasma atomic emission spectrometer for the determination of lead in whole blood.  

PubMed

The determination of lead in whole blood by atomic emission spectrometry using a capacitively coupled microwave plasma and a tungsten filament electrode is presented. When the plasma-supporting electrode is also used as the sample holder, transfer of the sample to the plasma is 100%. Microwaves are used to dry the sample and, at higher powers, ignite a helium plasma which results in the atomization and excitation of Pb. Using this methodology, a detection limit of 3 pg of Pb was obtained using 5-microL aqueous samples. The precision was 9%. Whole blood samples were subjected to a drying stage similar to that of the aqueous samples. Following this drying stage, a low-power (30 W) helium plasma was ignited and used to ash the blood sample. Higher power plasmas (> 150 W) were used to atomize and excite the Pb. Recovery of Pb from the blood samples was 88%, when compared to aqueous standards. PMID:8154584

Wensing, M W; Smith, B W; Winefordner, J D

1994-02-15

118

Observation and theoretical studies of microwave emission from thin saline ice  

SciTech Connect

The authors present experimental data on microwave emissions from thin saline ice forming in large experimental tanks. Ice cover plays a major role in energy balance in the polar regions, as it affects albedo and energy exchange and boundary layer structure. The thickness of sea ice strongly affects the interactions between the atmosphere and the oceans. Turbulent heat fluxes, ice growth rates, and oceanic salt fluxes can vary by several orders of magnitude between open water and areas with multiyear ice. This implies that small areas of open water or thin ice may have a major impact on energy balance in that immediate area. Present remote sensing systems are interpreted by algorithms which distinguish only open water, first year, and multiyear ice. This effort provides information on the microwave signatures of thin ice, with the intent that it aid in development of algorithms which can distinguish such ice cover from other surface layers to improve reliability of remote sensing measurements.

Wensnahan, M.R.; Grenfell, T.C.; Winebrenner, D.P.; Maykut, G.A. (Univ. of Washington, Seattle (United States))

1993-05-15

119

Sea Ice Emissivities and Effective Temperatures at MHS Frequencies: An Analysis of Airborne Microwave Data Measured During Two Arctic Campaigns  

Microsoft Academic Search

Satellite-based sounding of the temperature and hu- midity of the lower troposphere is only carried out over open sea surfaces because of large uncertainties in the surface emissivity and effective emitting temperature of other surfaces. The study of sea ice and snow surface emissivities at Microwave Humidity Sounder (MHS) frequencies has been the focus of two airborne campaigns carried out

R. Chawn Harlow

2011-01-01

120

THE LOCAL DUST FOREGROUNDS IN THE MICROWAVE SKY. I. THERMAL EMISSION SPECTRA  

SciTech Connect

Analyses of the cosmic microwave background (CMB) radiation maps made by the Wilkinson Microwave Anisotropy Probe (WMAP) have revealed anomalies not predicted by the standard inflationary cosmology. In particular, the power of the quadrupole moment of the CMB fluctuations is remarkably low, and the quadrupole and octopole moments are aligned mutually and with the geometry of the solar system. It has been suggested in the literature that microwave sky pollution by an unidentified dust cloud in the vicinity of the solar system may be the cause for these anomalies. In this paper, we simulate the thermal emission by clouds of spherical homogeneous particles of several materials. Spectral constraints from the WMAP multi-wavelength data and earlier infrared observations on the hypothetical dust cloud are used to determine the dust cloud's physical characteristics. In order for its emissivity to demonstrate a flat, CMB-like wavelength dependence over the WMAP wavelengths (3 through 14 mm), and to be invisible in the infrared light, its particles must be macroscopic. Silicate spheres of several millimeters in size and carbonaceous particles an order of magnitude smaller will suffice. According to our estimates of the abundance of such particles in the zodiacal cloud and trans-Neptunian belt, yielding the optical depths of the order of 10{sup -7} for each cloud, the solar system dust can well contribute 10 muK (within an order of magnitude) in the microwaves. This is not only intriguingly close to the magnitude of the anomalies (about 30 muK), but also alarmingly above the presently believed magnitude of systematic biases of the WMAP results (below 5 muK) and, to an even greater degree, of the future missions with higher sensitivities, e.g., Planck.

Dikarev, Valeri; Preuss, Oliver; Solanki, Sami; Krueger, Harald [Max-Planck-Institut fuer Sonnensystemforschung, 37191 Katlenburg-Lindau (Germany); Krivov, Alexander [Friedrich-Schiller Universitaet Jena (Germany)

2009-11-01

121

ARTICLES: Anomalously wide continuous tuning range of the emission frequency of an injection laser with an external selective resonator  

NASA Astrophysics Data System (ADS)

A study was made of an anomalously wide continuous tuning range of the emission frequency of an injection laser with an external resonator operating under conditions of self-stabilized single-frequency lasing. The self-stabilization was observed for a large number of lasers with different structures, both at room and liquid nitrogen temperatures. A study was made of the influence of the power, degree of coupling with the external part of the laser, resonator length, and pass band of a selective component on the continuous tuning range. In the self-stabilization regime this range was 10-30 times greater than the corresponding range for a laser operating under conventional conditions. A nontrivial feature of hopping between longitudinal laser modes at the limit of the tuning range was observed. This feature was explained on the basis of a theory proposed by Bogatov, Eliseev, Okhotnikov, Rakhval'skii, and Khairetdinov [Sov. J. Quantum Electron. 13, 1221 (1983)].

Akul'shin, A. M.; Bazhenov, V. Yu; Velichanski?, V. L.; Zverkov, M. V.; Zibrov, A. S.; Nikitin, V. V.; Okhotnikov, O. G.; Sautenkov, V. A.; Senkov, N. V.; Yurkin, E. K.

1986-07-01

122

Microwave coherent emissions from solar flares - a look at through a large interferometer  

NASA Astrophysics Data System (ADS)

The report discusses the results of microwave observations of coherent emission sources with broadband spectropolarimeters and the Siberian Solar Radio Telescope (receiving frequency about 5.7 GHz). To date, more than 300 events with narrowband subsecond pulses were recorded. It is revealed that at the small real sizes of sources their apparent sizes can reach the SSRT beam width (? 15 arcsec) due to electromagnetic wave scattering by density fluctuations in the lower corona, or due to emission reflection from the underlying layers of the solar atmosphere. The fine emission sources usually occur near tops of the flare loops. In some events it was possible to reveal plasma parameters in the vicinity of the fine emission exciters from the X-ray, optical and continuum microwave images, and to identify the mechanisms of the coherent emission. The SSRT is an interferometer that allows to record spatial brightness distributions of a flare region at two close frequencies simultaneously. Such observations have showed that the frequency dynamics of fast drifting narrowband bursts (type III - like) is controlled not only by the velocity of exciter movement through gradients of the plasma parameters, but also by rapid changes in plasma parameters over time. We discuss the diagnostic potential of the observations of coherent emission sources and new possibilities of the instruments which are under construction now. The work is supported by the Ministry of education and science of the Russian Federation (State Contracts 16.518.11.7065 and 02.740.11.0576), and by the grants RFBR (12-02-91161-GFEN-a, 12-02-00616 and 12-02-00173-a

Altyntsev, Alexandre; Sergei, Lesovoi; Natalia, Meshalkina; Dmitrii, Zhdanov; Natalia, Korolkova

2013-04-01

123

Regionalization of Methane Emissions in the Amazon Basin with Multi-temporal Microwave Remote Sensing  

NASA Astrophysics Data System (ADS)

Remote sensing of the Amazon basin with passive and active microwave techniques were applied to determine the temporally varying extent of inundation and associated vegetation, and used in conjunction with field measurements to calculate regional rates of methane emission from wetlands to the atmosphere. Monthly inundation areas were derived from analysis of the 37-GHz polarization difference observed by the Scanning Multichannel Microwave Radiometer (1979 -87) for the mainstem Amazon floodplain in Brazil, the Llanos de Moxos (Beni and Mamore rivers) in Bolivia, the Bananal Island (Araguaia River) and Roraima savannas. Data from the Japanese Earth Resources Satellite-1, L-band synthetic aperture radar were used to determine inundation and wetland vegetation for Amazon basin less than 500 m above sea level at high water (May-June 1996) and low water (October 1995). Although all the measurements of methane emission from aquatic habitats have been performed in the deeply inundated, central basin in open water, flooded forests or floating macrophytes, our basin-wide remote sensing has revealed large areas of seasonally flooded savannas. Therefore, improvements in basin-wide estimates of methane emission will require field studies in wetlands such as those in Bolivia, Roraima and the Bananal.

Melack, J. M.; Hess, L. L.; Forsberg, B. R.; Hamilton, S. K.; Novo, E. M.

2002-12-01

124

Unique Properties of Thermally Tailored Copper: Magnetically Active Regions and Anomalous X-ray Fluorescence Emissions.  

PubMed

When high-purity copper (>/=99.98%(wt)) is melted, held in its liquid state for a few hours with iterative thermal cycling, then allowed to resolidify, the ingot surface is found to have many small regions that are magnetically active. X-ray fluorescence analysis of these regions exhibit remarkably intense lines from "sensitized elements" (SE), including in part or fully the contiguous series V, Cr, Mn, Fe, and Co. The XRF emissions from SE are far more intense than expected from known impurity levels. Comparison with blanks and standards show that the thermal "tailoring" also introduces strongly enhanced SE emissions in samples taken from the interior of the copper ingots. For some magnetic regions, the location as well as the SE emissions, although persistent, vary irregularly with time. Also, for some regions extraordinarily intense "sensitized iron" (SFe) emissions occur, accompanied by drastic attenuation of Cu emissions. PMID:20037657

Nagel, Christopher J; Herschbach, Dudley R

2009-11-19

125

Investigations of newly formed sea ice in the Cape Bathurst polynya: 2. Microwave emission  

NASA Astrophysics Data System (ADS)

This study examines the role of newly formed sea ice geophysical state on microwave emission. Coincident with sea ice geophysical sampling, ship-based passive microwave emission data (dual-polarized at 19, 37 and 85 GHz) were collected in the Cape Bathurst Polynya during 18 October and 13 November 2003. Using polarization ratios (PRs), we found that bare thin ice was separable from snow-covered ice. Thin snow (equal to 0.02-0.13 m) thickness is significantly correlated with the spectral gradient ratios GRV(85,19) (R2 = 0.55, P-value <0.05) and GRV(85,37) (R2 = 0.66, P-value < 0.05), but not with GRV(37,19) (R2 = 0.19, P-value > 0.2). The relationship between atmospherically corrected R37 and bare ice thickness showed an exponential relationship very comparable to that reported by [2004], which is ascribed to the reduction of bare ice surface salinity based on both observational and modeling studies. However, the relationship quickly becomes invalid for even thin snow covered ice, due to significant impact of thin wet (liquid water fraction ˜0.02-0.04) snow on microwave emission. Our results suggest that the sea ice algorithms NASA Team and NASA Team 2 could underestimate total ice concentration over thin bare ice by 35% on average, while both algorithms underestimate the total ice concentration by 20% over snow-covered ice. Using PR(85) sea ice could be delineated from open water using a properly adjusted threshold value accounting for cloud or fog effects, possibly with the exception of dark nilas and/or bare consolidated pancakes.

Hwang, Byong Jun; Ehn, Jens K.; Barber, David G.; Galley, Ryan; Grenfell, Thomas C.

2007-05-01

126

Microwave emission from late-type dwarf stars UV Ceti and YZ Canis Minoris  

NASA Astrophysics Data System (ADS)

Simultaneous high-resolution observations of two late-type dwarf stars, UV Cet and YZ CMi, at 6 and 20 cm are presented. These observations put sufficient constraints on existing interpretations to conclude that the quiescent microwave emission from these stars is due to gyrosynchrotron radiation of nonthermal electrons having a power-law energy distribution. From the lifetime of 1 hr of the nonthermal particles against radiation and collision losses, a magnetic field of a few thousand gauss on the photosphere of these stars is estimated. The observations indicate that the ambient density in the coronae of YZ CMi is an order of magnitude higher than that of UV Cet.

Kundu, M. R.; Shevgaonkar, R. K.

1985-10-01

127

Polarization control of microwave emission from high power rectangular cross-section gyrotron devices  

Microsoft Academic Search

Results are summarized of experiments on a gyrotron utilizing a rectangular-cross-section (RCS) cavity region. The major issue under investigation is polarization control of microwave emission as a function of magnetic field. The electron beam driver is the Michigan Electron Long Beam Accelerator (MELBA) at parameters: V=0.8 MV, Idiode=1-10 kA, Itube=0.1=0.5 kA, and te-beam=0.4-1.0 ?s. The annular e-beam is spun up

Jonathan M. Hochman; Ronald M. Gilgenbach; Reginald L. Jaynes; Joshua I. Rintamaki; Y. Y. Lau; William E. Cohen; Chris W. Peters; Thomas A. Spencer

1998-01-01

128

Temperature profile determination from microwave oxygen emissions in limb sounding geometry  

NASA Astrophysics Data System (ADS)

We present a theoretical investigation of the temperature profile retrieval capabilities of oxygen emission lines in the microwave. The main focus is on two strong lines, both allowing temperature retrieval throughout the mesosphere. One is within the oxygen cluster at 61.15 GHz, the other one is isolated at 118.75 GHz. A thorough comparison of these two lines is presented. Several instrumental parameters such as system noise temperature, antenna beam width, filter width, and coverage of the line are assessed, as well as the possible impact of an error in the spectroscopic parameters. The instrumental setup follows roughly the specifications for the Millimeter Wave Acquisitions for Stratosphere/Troposphere Exchange Research (MASTER) instrument, serving as a basis for a modern passive microwave instrument. The instrumental parameters have also been varied in order to allow comparisons with two instruments that use the 118.75-GHz line for temperature profile determination, the Odin submillimeter radiameter (SMR) and the EOS microwave limb sounder (MLS). Simultaneous retrieval of temperature and pointing bias is performed with the Optimal Estimation Method. We find temperature retrieval errors of <5 K in the mesosphere, and at sub-Kelvin level in the lower stratosphere. Good knowledge of spectroscopic parameters is required for accurate retrievals. The simultaneous retrieval of a pointing bias can reduce the impact of spectroscopic parameter errors on the temperature retrieval.

von Engeln, Axel; Bühler, Stefan

2002-10-01

129

Microwave observations of jupiter's synchrotron emission during the galileo flyby of amalthea in 2002.  

NASA Astrophysics Data System (ADS)

In November, 2002, the Galileo spacecraft trajectory provided a close flyby of Amalthea, one of Jupiter's inner most moons (˜2.4 RJ). During this pass, Galileo entered into a region rarely explored by spacecraft, the inner radiation belts of Jupiter. We present preliminary results from a campaign of microwave observations of Jovian synchrotron emission over a six month interval centered around the flyby. The observations were made with NASA's Deep Space Network (DSN) antennas at Goldstone, California, and the NRAO Very Large Array. We report preliminary measurements of the flux density of the synchrotron emission and the rotational beaming curves and a compare them with the long term history of Jupiter's microwave emission which varies significantly on timescales of months to years. The new data are also being examined to search for evidence of short-term variations and to compare single aperture beaming curves with the spatially resolved images obtained with the VLA. These radio astronomy data will be combined with in-situ measurements from Galileo (see companion paper by Bolton et al) to improve models of the synchrotron emission from Jupiter's radiation belts. A large percentage of the Goldstone observations were conducted by middle- and high school students from classrooms across the nation. The students and their teachers are participants in the Goldstone-Apple Valley Radio Telescope (GAVRT) science education project, which is a partnership involving NASA, the Jet Propulsion Laboratory and the Lewis Center for Educational Research (LCER) in Apple Valley, CA. Working with the Lewis Center over the Internet, GAVRT students conduct remotely controlled radio astronomy observations using 34-m antennas at Goldstone. The JPL contribution to this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration 2756 Planetary magnetospheres (5443, 5737, 6030) 6218 Jovian satellites 6220 Jupiter Planetary Sciences

Klein, M. J.; Bolton, S. J.; Bastian, T. S.; Blanc, M.; Levin, S. M.; McLeod, R. J.; MacLaren, D.; Roller, J. P.; Santos-Costa, D.; Sault, R.

2003-04-01

130

Sequentially emission line addressing by microwave driven mercury free low pressure lamps  

NASA Astrophysics Data System (ADS)

As the use of mercury vapor lamps for lighting purposes will be banned in the European Union after 2015, finding a replacement for mercury in fluorescent lamps has become a challenge. Several low pressure gas discharge systems containing metal halides have been reported in the last decade. Examples are halides of indium and thallium with argon as auxiliary gas, which generate ultraviolet and visible emission lines. The peak emission intensities are adjustable by variation of plasma parameters, which allows addressing the color temperature of the lamp. In this contribution, we report on the effects of auxiliary gas pressure, cold spot temperatures and power densities for low pressure metal halide lamps filled with indium and thallium with regard to its spectral output. Since the guided surface wave discharge is the only method to increase the lamps power without changing the amplitude of the maintenance electrical field; the lamp discharges are sustained by microwave excited guided surface waves. A surfatron is used as coupling device of microwave energy.

Ögün, C. M.; Kaiser, Ch.; Kling, R.

2011-11-01

131

Temperature Profile Determination From Microwave Oxygen Emissions in Limb Sounding Geometry  

NASA Astrophysics Data System (ADS)

Oxygen emission lines are particularly useful for atmospheric temperature profile determination, because oxygen has a known, constant volume mixing ratio profile. Emission lines in the microwave around 60 GHz were used for temperature retrieval by the Microwave Limb Sounder (MLS), and the Millimeter-Wave Atmospheric Limb Sounder (MAS). More recent instruments focus on the oxygen transition at 118 GHz, like the ODIN instrument, and the EOS-MLS. We present an investigation of the retrieval capabilities of two strong oxygen lines, both allowing temperature retrieval throughout the mesosphere, one within the oxygen cluster at 61.15 GHz, the other one at 118.75 GHz. Several instrumental parameters like antenna, and filter width, are assessed, as well as the impact of errors in spectroscopic parameters. The instrumental setup follows the MASTER instrument, conceived as a core instrument in a future ESA Atmospheric Chemistry Explorer mission. Simultaneous retrieval of temperature and a reference pressure is performed by employing the Optimal Estimation Method. We find temperature retrieval errors below 5 K in the mesosphere, and at sub-Kelvin level in the lower stratosphere. The retrieval of a reference pressure can reduce the impact of errors in spectroscopic parameters on the temperature retrieval, but this has to be judged against the error in the reference pressure, and the possible impact on the retrieved tangent altitude.

von Engeln, A.; von Engeln, A.; Buehler, S.; Nedoluha, G.

2001-05-01

132

Use of a One-Dimensional Variational Retrieval to Diagnose Estimates of Infrared and Microwave Surface Emissivity Over Land for ATOVS Sounding Instruments  

Microsoft Academic Search

A 1-D variational retrieval of surface emissivity is developed and applied for the Advanced Microwave Sounding Unit modules A and B, along with the High-resolution Infrared Radiation Sounder. This algorithm offers simultaneous retrieval of infrared and microwave emissivity and increases the separation of the emissivity and land surface temperature signals. The initial estimate of the emissivity for the surface-sensitive channels

Benjamain Ruston; Fuzhong Weng; Banghua Yan

2008-01-01

133

Measurement of Anomalous High-Frequency Oscillations during Field Emission and Their Possible Significance in Pulsed Field Emission  

Microsoft Academic Search

Trains of evenly spaced 20 ns wide (width at half-height) current pulses with a repetition rate of 200 MHz were measured from a tungsten tip in vacuum when a DC high-voltage supply, a 100 MOmega ballast resistor, a 50 Omega load resistor, and an analog microammeter were connected in series with a field emission tube. These current pulses have peak

M. J. Hagmann; D. A. Christensen; M. S. Mousa; A. Baturin; E. P. Sheshin

2006-01-01

134

China Probe CE1 Unveils the World First Moon-Globe Microwave Emission Map --- The Microwave Moon: Some Exploration Results of Change'E-1 Microwave Sounder  

Microsoft Academic Search

With the data obtained by the China probe Chang'E-1 Lunar Microwave Sounder (CELMS), China has created a Moon globe microwave brightness temperature distribution map, and some new conclusions were drawn from it, which will make the Moon closer to its true nature.

J. S. Jiang; Z. Z. Wang; X. H. Zhang; D. H. Zhang; J. Wu; Y. Li; L. Q. Lei; W. G. Zhang; H. Y. Cui; W. Guo; D. H. Li; X. L. Dong; H. G. Liu

2010-01-01

135

In search of water vapor on Jupiter: Laboratory measurements of the microwave properties of water vapor and simulations of Jupiter's microwave emission in support of the Juno Mission  

NASA Astrophysics Data System (ADS)

This research has involved the conduct of a series of laboratory measurements of the centimeter-wavelength opacity of water vapor along with the development of a hybrid radiative transfer ray-tracing simulator for the atmosphere of Jupiter which employs a model for water vapor opacity derived from the measurements. For this study an existing Georgia Tech high-sensitivity microwave measurement system (Hanley and Steffes, 2007) has been adapted for pressures ranging from 12--100 bars, and a corresponding temperature range of 293--525°K. Water vapor is measured in a mixture of hydrogen and helium. Using these measurements which covered a wavelength range of 6--20 cm, a new model is developed for water vapor absorption under Jovian conditions. In conjunction with our laboratory measurements, and the development of a new model for water vapor absorption, we conduct sensitivity studies of water vapor microwave emission in the Jovian atmosphere using a hybrid radiative transfer ray-tracing simulator. The approach has been used previously for Saturn (Hoffman, 2001), and Venus (Jenkins et al., 2001). This model has been adapted to include the antenna patterns typical of the NASA Juno Mission microwave radiometer (NASA/Juno-MWR) along with Jupiter's geometric parameters (oblateness), and atmospheric conditions. Using this adapted model we perform rigorous sensitivity tests for water vapor in the Jovian atmosphere. This work will directly improve our understanding of microwave absorption by atmospheric water vapor at Jupiter, and improve retrievals from the Juno microwave radiometer. Indirectly, this work will help to refine models for the formation of Jupiter and the entire solar system through an improved understanding of the planet-wide abundance of water vapor which will result from the successful opreation of the Juno Microwave Radiometer (Juno-MWR).

Karpowicz, Bryan Mills

136

High emission current density microwave-plasma-grown carbon nanotube arrays by postdepositional radio-frequency oxygen plasma treatment  

SciTech Connect

Highly stable field emission current densities of more than 6 A/ cm{sup 2} along with scalable total field emission currents of {approx}300 {mu}A per 70 {mu}m diameter carbon nanotube (CNT)-covered electron emitter dot are reported. Microwave-plasma chemical vapor deposition, along with a novel catalyst sandwich structure and postdepositional radio-frequency (rf) oxygen plasma treatment lead to well-structured vertically aligned CNTs with excellent and scalable emission properties. Scanning electron and transmission electron microscope investigations reveal that postdepositional treatment reduces not only the number but modifies the structure of the CNTs. Well-structured microwave-plasma-grown nanotubes become amorphous during rf oxygen plasma treatment and the measured work functions of CNTs change from 4.6 eV to 4.0 eV before and after treatment, respectively. Our experiments outline a novel fabrication route for structured CNT arrays with improved and scalable field emission characteristics.

Chen, Z.; Engelsen, D. den; Bachmann, P.K.; Elsbergen, V. van; Koehler, I.; Merikhi, J.; Wiechert, D.U. [School of Optoelectronic Information, University of Electronic Science and Technology of China, Jianshebei Road 4, 610054 Chengdu (China) and Philips Research Laboratories, Weisshausstrasse 2, D-52066 Aachen (Germany); School of Optoelectronic Information, University of Electronic Science and Technology of China, Jianshebei Road 4, 610054 Chengdu (China); Philips Research Laboratories, Weisshausstrasse 2, D-52066 Aachen (Germany)

2005-12-12

137

High emission current density microwave-plasma-grown carbon nanotube arrays by postdepositional radio-frequency oxygen plasma treatment  

NASA Astrophysics Data System (ADS)

Highly stable field emission current densities of more than 6 A/ cm2 along with scalable total field emission currents of ~300 ?A per 70 ?m diameter carbon nanotube (CNT)-covered electron emitter dot are reported. Microwave-plasma chemical vapor deposition, along with a novel catalyst sandwich structure and postdepositional radio-frequency (rf) oxygen plasma treatment lead to well-structured vertically aligned CNTs with excellent and scalable emission properties. Scanning electron and transmission electron microscope investigations reveal that postdepositional treatment reduces not only the number but modifies the structure of the CNTs. Well-structured microwave-plasma-grown nanotubes become amorphous during rf oxygen plasma treatment and the measured work functions of CNTs change from 4.6 eV to 4.0 eV before and after treatment, respectively. Our experiments outline a novel fabrication route for structured CNT arrays with improved and scalable field emission characteristics.

Chen, Z.; den Engelsen, D.; Bachmann, P. K.; van Elsbergen, V.; Koehler, I.; Merikhi, J.; Wiechert, D. U.

2005-12-01

138

Retrievals of Sulfur-Bearing Gas Abundances from Microwave Emission Maps of Venus Obtained at the VLA  

Microsoft Academic Search

We present retrievals of abundances of sulfur dioxide and gaseous sulfuric acid vapor from microwave emission maps of Venus obtained at the VLA in April, 1996 at 15 GHz and 22.5 GHz. Temperature\\/pressure profiles obtained with the Magellan spacecraft are imported into the radiative transfer model, where it is assumed that the thermal structure of the Venus atmosphere does not

J. M. Jenkins; B. J. Butler; P. G. Steffes; M. A. Kolodner

1998-01-01

139

ROSAT PSPC X-ray observations of NGC 4258: Detection of point sources, 4 million K halo emission, and anomalous arms  

NASA Astrophysics Data System (ADS)

The highly inclined spiral galaxy NGC 4258 (M106) has been observed in X-rays with the Position Sensitive Proportional Counter (PSPC) of the Rontgen observatory ROSAT. Following X-ray components have been identified in the central 40 min x 40 min field: (1) Several pointlike X-ray sources, some of which can be identified as blue stellar objects and/or coincide with compact radio sources. Two of them are 18 min apart, symmetrically aligned, and equidistant to the nucleus of NGC 4258 with a position angle connecting the tips of the anomalous arms. (2) Extended (approx. 3 min) X-ray emission from an uncataloged cluster of galaxies with gas at temperature greater than 20 million K. (3) Emission from UGC 7356, a dwarf companion of NGC 4258 with a X-ray luminosity of 1.3 x 1038 erg/s. (4) Complex emission from NGC 4258 with total X-ray luminosity of 5.6 x 1039 erg/s. The X-ray emission from the outer regions of NGC 4258 can be separated into 3 components: (1) Seven pointlike sources in the spiral arms of NGC 4258 with total X-ray luminosity of 6 x 1038 erg/s. (2) Extended emission from a 3.6 million K gas in the halo of NGC 4258. On the east side of the galaxy the emission is detected in the soft and hard band, on the west side only in the hard band. This can be explained by shadowing of the X-ray emission of the halo gas by cool gas in the disk of NGC 4258, that has been observed in HI. The luminosity of this emission is 5.1 x 1039 erg/s. (3) Hard X-ray emission specifically in the northwest side of the galaxy is strongly enhanced where the anomalous spiral arms have been detected in H alpha and radio. The soft halo gas emission has been modeled sucessfully by an isothermal gas sphere with a constant density profile or, even better, with barometrically stacked shells. The diffuse halo emission and the hard X-ray emission connected with the anomalous arms strongly argue for a ballistic interpretation for the origin of these arms. While the diffuse hard X-ray emission in the northwest follows closely the anomalous arm contours and the plateau, X-ray emission corresponding to the anomalous arm in the southwest is more concealed by the halo emission. A search for X-ray emission from SN1980K in NGC 4258 and for residual X-ray emission from the outer disk of NGC 4258 was not successful. The Seyfert 1.9 nucleus of NGC 4258 is not detected as a point source, as it is likely to be heavily absorbed. The X-ray properties of NGC 4258 as a Seyfert 2 galaxy are discussed in the light of the unified active galactic nuclei (AGN) scheme.

Pietsch, W.; Vogler, A.; Kahabka, P.; Jain, A.; Klein, U.

1994-04-01

140

Center-to-Limb Variation of Microwave Emissions from Thermal-Rich and Thermal-Poor Solar Flares  

NASA Astrophysics Data System (ADS)

Non-thermal microwave emissions observed in the impulsive phase of solar flares are produced by the gyrosynchrotron mechanism, which depends on a number of physical parameters such as electron energy spectra, their pitch angle distribution, magnetic field strength, angle between line of sight and the magnetic field (viewing angle), and the number of electrons. Therefore, it is difficult to determine those physical parameters uniquely only from the observed quantities of individual microwave burst. Statistical analysis of microwave bursts by using a number of flare events provide us a way to find mutual relationships between different quantities, and thus are useful to restrict the possible domain of those physical quantities of the microwave source. The pitch angle distribution of accelerated electrons is of a crucial importance for the problem of particle acceleration in solar flares. A clue to know the pitch angle distribution of accelerated particles could be obtained from the center-to-limb variations of observed microwave emissions, since relativistic electrons trapped in flare loops emit the microwaves to the direction of their velocity, and the viewing angle effect, i.e., center-to-limb variation of the flare emission, can be related to the pitch angle distribution of accelerated electrons. A statistical analysis of microwave flare events is performed by using the event list of Nobeyama Radioheliograph in 1996-2009. We examine center-to-limb variations of17GHz and 34GHz flux by dividing the flare events into different groups with respect to the 'thermal plasma richness' (ratio of the peak flux of soft X-ray to non-thermal microwave emissions) and the duration of microwave bursts. It is found that peak flux of 17 and 34GHz tend to be higher toward the limb for thermal-rich flares with short durations. We propose that the thermal-rich flares, which are supposed to be associated with an efficient precipitation of high energy particles into the chromosphere, have a pitch angle distribution of non-thermal electrons with a higher population along the flare loop.

Kawate, T.; Asai, A.; Ichimoto, K.

2011-12-01

141

FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: GALACTIC FOREGROUND EMISSION  

SciTech Connect

We present a new estimate of foreground emission in the Wilkinson Microwave Anisotropy Probe (WMAP) data, using a Markov chain Monte Carlo method. The new technique delivers maps of each foreground component for a variety of foreground models with estimates of the uncertainty of each foreground component, and it provides an overall goodness-of-fit estimate. The resulting foreground maps are in broad agreement with those from previous techniques used both within the collaboration and by other authors. We find that for WMAP data, a simple model with power-law synchrotron, free-free, and thermal dust components fits 90% of the sky with a reduced {chi}{sup 2} {sub {nu}} of 1.14. However, the model does not work well inside the Galactic plane. The addition of either synchrotron steepening or a modified spinning dust model improves the fit. This component may account for up to 14% of the total flux at the Ka band (33 GHz). We find no evidence for foreground contamination of the cosmic microwave background temperature map in the 85% of the sky used for cosmological analysis.

Gold, B.; Bennett, C. L.; Larson, D. [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Hill, R. S.; Odegard, N.; Weiland, J. L. [Adnet Systems, Inc., 7515 Mission Dr., Suite A1C1 Lanham, Maryland 20706 (United States); Hinshaw, G.; Kogut, A.; Wollack, E. [Code 665, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Page, L.; Dunkley, J.; Jarosik, N. [Department of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544-0708 (United States); Spergel, D. N. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544-1001 (United States); Halpern, M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Komatsu, E. [Department of Astronomy, University of Texas, Austin, 2511 Speedway, RLM 15.306, Austin, TX 78712 (United States); Meyer, S. S. [Departments of Astrophysics and Physics, KICP and EFI, University of Chicago, Chicago, IL 60637 (United States); Nolta, M. R. [Canadian Institute for Theoretical Astrophysics, 60 St. George St, University of Toronto, Toronto, ON M5S 3H8 (Canada); Wright, E. L. [PAB 3-909, UCLA Physics and Astronomy, P.O. Box 951547, Los Angeles, CA 90095-1547 (United States)], E-mail: bgold@pha.jhu.edu

2009-02-15

142

Control of nitric oxide, nitrous oxide, and ammonia emissions using microwave plasmas  

PubMed

The subject of this paper is mitigation of the undesirable side-effects of selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR): ammonia slip, residual NO(x), and N(2)O emissions. The use of microwave-plasma discharge within the flue gas was explored as a potential pollution-control method. The key issues addressed were: (1) N(2)O, NH(3), and NO removal efficiencies; and (2) sustaining a stable plasma at atmospheric, or close to atmospheric, pressure. In non-oxidizing atmospheres, removal efficiencies were always close to 100% for all species. In the presence of oxygen, however, appreciable amounts of nitric oxide and ammonia were formed. Methods leading to preventing these undesirable effects were examined. In a number of runs, stable plasma operation was attained at pressures close to atmospheric. PMID:10781719

Wojtowicz; Miknis; Grimes; Smith; Serio

2000-05-29

143

Radio emission and anomalous changes in electrical conductivity in heated rock and mineral specimens  

Microsoft Academic Search

Conclusions  \\u000a \\u000a \\u000a \\u000a 1. \\u000a \\u000a On heating, the processes of dehydration, decrepitation, polymorphic transitions, etc. in rock and mineral specimens, i.e.,\\u000a transition of their crystal lattices to energetically more profitable states, cause the emission of electromagnetic radiation\\u000a over a wide range of wavelengths.\\u000a \\u000a \\u000a \\u000a \\u000a 2. \\u000a \\u000a In quartz, fluorite, and certain rocks containing these minerals, the decrease in electrical conductivity is due to decrepitation\\u000a of

A. A. Vorob'ev; V. N. Sal'nikov

1976-01-01

144

Airborne Measurement of Microwave EmisSION FROM THE Earth's Surface and Atmosphere.  

National Technical Information Service (NTIS)

This paper reveals the results of a theoretical and experimental investigation of the microwave radiation emitted by the Earth's surface and atmosphere. The study objective was to evaluate the potential application of microwave radiometry to weather satel...

H. A. Hyatt

1965-01-01

145

Anomalous Water.  

National Technical Information Service (NTIS)

Of the many anomalies reported for water, the study concentrated on those anomalous properties exhibited by three types of material--the bound water in animate nature, the interfacially or structurally ordered water in inanimate nature, and the anomalous ...

B. D. Allan R. L. Norman

1970-01-01

146

Microwave absorption properties and infrared emissivities of ordered mesoporous C-TiO2 nanocomposites with crystalline framework  

NASA Astrophysics Data System (ADS)

Ordered mesoporous C-TiO2 nanocomposites with crystalline framework were prepared by the evaporation-induced triconstituent co-assembly method. The products were characterized by XRD, TEM, N2 adsorption-desorption and TG. Their microwave absorption properties were investigated by mixing the product and epoxy resin. It is found that the peak with minimum reflection loss value moves to lower frequencies and the ordered mesoporous C-TiO2 nanocomposite possesses an excellent microwave absorbing property with the maximum reflection loss of -25.4 dB and the bandwidth lower than -10 dB is 6.6 GHz. The attenuation of microwave can be attributed to dielectric loss and their absorption mechanism is discussed in detail. The mesoporous C-TiO2 nanocomposites also exhibit a lower infrared emissivity in the wavelength from 8 to 14 ?m than that of TiO2-free powder.

Wang, Tao; He, Jianping; Zhou, Jianhua; Tang, Jing; Guo, Yunxia; Ding, Xiaochun; Wu, Shichao; Zhao, Jianqing

2010-12-01

147

Anomalous resistivity effect on multiple ion beam emission and hard x-ray generation in a Mather type plasma focus device  

SciTech Connect

Multi ion beam and hard x-ray emissions were detected in a high inductance (more than 100 nH) Mather type plasma focus (PF) device at different filling gas pressures and charging voltages. The signal analysis was performed through the current trace, as it is the fundamental signal from which all of the phenomena in a PF device can be extracted. Two different fitting processes were carried out according to Lee's computational (snow-plow) model. In the first process, only plasma dynamics and classical (Spitzer) resistances were considered as energy consumer parameters for plasma. This led to an unsuccessful fitting and did not answer the energy transfer mechanism into plasma. A second fitting process was considered through the addition of anomalous resistance, which provided the best fit. Anomalous resistance was the source of long decrease in current trace, and multi dips and multi peaks of high voltage probe. Multi-peak features were interpreted considering the second fitting process along with the mechanisms for ion beam production and hard x-ray emission. To show the important role of the anomalous resistance, the duration of the current drop was discussed.

Behbahani, R. A.; Aghamir, F. M. [Department of Physics, University of Tehran, N. Kargar Ave, Tehran 14399 (Iran, Islamic Republic of)

2011-10-15

148

Microwave and radio emission of dusty star-forming galaxies: implication for the cosmic radio background  

NASA Astrophysics Data System (ADS)

We use the most up-to-date cosmological evolution models of dusty star-forming galaxies and radio sources to compute the extragalactic number counts and the cosmic background from 408 MHz to 12 THz (or 24 ?m). The evolution model of star-forming galaxies reproduces the recent constraints obtained by Spitzer, Herschel, and ground-based submm and mm experiments: number counts, redshift distribution of galaxies, cosmic background intensity and anisotropies. The template spectral energy distributions used in this model are extrapolated to the radio domain adding three emission components: synchrotron, free-free, and spinning dust. To fix the synchrotron intensity, we use the well-known IR/radio flux ratio, q70, and a constant spectral index ?S = -3, consistent with measurements made in local galaxies taking account the spinning dust emission. For a constant q70, our model added to the active galactic nucleus (AGN) contribution provides a good fit to the extragalactic number counts from 24 ?m to 408 MHz, and to the cosmic background intensity in the far- and mid-IR. The spinning dust emission accounts for up to 20% of the cosmic microwave background produced by star-forming galaxies, but for only less than 10% of the total background when AGN are included. The star-forming galaxies account for 77.5% of the number counts at 1.4 GHz for a flux of 100 ?Jy. However, the model falls short of reproducing the cosmic radio background measured with the ARCADE2 balloon-borne experiment. Considering the case when q70 decreases strongly with redshift, this still does not explain the ARCADE2 measurements. It also yields to an overestimate of the low-flux number counts in the radio. As a result, we rule out a steep variation of q70 with the redshift at least for z ? 3.5 . Then, adding a population of faint star-forming galaxies at high redshift (LIR ? 1011 L? and 4 ? z ? 6), which would be able to reproduce the ARCADE2 measurements, leads to predictions of the cosmic IR background much higher than what is currently observed, ruling out this as the explanation for the ARCADE2 results. Considering our findings and previous studies of the diffuse extragalactic radio emission, we conclude that if the radio emission measured by ARCADE2 is astrophysical in origin, it has to originate in the Galaxy or to originate in a new kind of radio sources (with no mid- to far-IR counterparts) or emission mechanism still to be discovered.

Ysard, N.; Lagache, G.

2012-11-01

149

Workshop on Microwave Scattering and Emission from the Earth's Surface held in Washington, D.C. on 11-12 April 1985  

Microsoft Academic Search

A workshop on microwave scattering and emission from the Earth's surface produced the following reports: Overview of Dense Medium Modeling; Radiative Transfer Equations Modified for Dense; Laboratory Experiments and Modeling of Multiple Scattering in Dense Discrete Scatters; Transport Theory for Random Waves through Pair-Correlated Discrete Scatters; Microwave Observations of Soil and Snow; Overview of Discrete Media Modeling; Scattering Amplitude Models

Keith R. Carver; Roger Lang

1986-01-01

150

Determining Foreground Contamination in Cosmic Microwave Background Observations: Diffuse Galactic Emission in the MAXIMA-I Field  

NASA Astrophysics Data System (ADS)

Observations of the cosmic microwave background (CMB) can be contaminated by diffuse foreground emission from sources such as Galactic dust and synchrotron radiation. In these cases, the morphology of the contaminating source is known from observations at different frequencies, but not its amplitude at the frequency of interest for the CMB. We develop a technique for accounting for the effects of such emission in this case, and for simultaneously estimating the foreground amplitude in the CMB observations. We apply the technique to CMB data from the MAXIMA-1 experiment, using maps of Galactic dust emission from combinations of IRAS and DIRBE observations, as well as compilations of Galactic synchrotron emission observations. The spectrum of the dust emission over the 150-450 GHz observed by MAXIMA is consistent with preferred models, but the effect on CMB power spectrum observations is negligible.

Jaffe, A. H.; Balbi, A.; Bond, J. R.; Borrill, J.; Ferreira, P. G.; Finkbeiner, D.; Hanany, S.; Lee, A. T.; Rabii, B.; Richards, P. L.; Smoot, G. F.; Stompor, R.; Winant, C. D.; Wu, J. H. P.

2004-11-01

151

SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: GALACTIC FOREGROUND EMISSION  

SciTech Connect

We present updated estimates of Galactic foreground emission using seven years of WMAP data. Using the power spectrum of differences between multi-frequency template-cleaned maps, we find no evidence for foreground contamination outside of the updated (KQ85y7) foreground mask. We place a 15 {mu}K upper bound on rms foreground contamination in the cleaned maps used for cosmological analysis. Further, the cleaning process requires only three power-law foregrounds outside of the mask. We find no evidence for polarized foregrounds beyond those from soft (steep-spectrum) synchrotron and thermal dust emission; in particular we find no indication in the polarization data of an extra 'haze' of hard synchrotron emission from energetic electrons near the Galactic center. We provide an updated map of the cosmic microwave background (CMB) using the internal linear combination method, updated foreground masks, and updates to point source catalogs using two different techniques. With additional years of data, we now detect 471 point sources using a five-band technique and 417 sources using a three-band CMB-free technique. In total there are 62 newly detected point sources, a 12% increase over the five-year release. Also new are tests of the Markov chain Monte Carlo foreground fitting procedure against systematics in the time-stream data, and tests against the observed beam asymmetry. Within a few degrees of the Galactic plane, the behavior in total intensity of low-frequency foregrounds is complicated and not completely understood. WMAP data show a rapidly steepening spectrum from 20 to 40 GHz, which may be due to emission from spinning dust grains, steepening synchrotron, or other effects. Comparisons are made to a 1 deg 408 MHz map (Haslam et al.) and the 11 deg ARCADE 2 data (Singal et al.). We find that spinning dust or steepening synchrotron models fit the combination of WMAP and 408 MHz data equally well. ARCADE data appear inconsistent with the steepening synchrotron model and consistent with the spinning dust model, though some discrepancies remain regarding the relative strength of spinning dust emission. More high-resolution data in the 10-40 GHz range would shed much light on these issues.

Gold, B.; Bennett, C. L.; Larson, D. [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Odegard, N.; Weiland, J. L.; Hill, R. S. [Adnet Systems, Inc., 7515 Mission Dr., Suite A1C1 Lanham, MD 20706 (United States); Kogut, A.; Hinshaw, G. [Code 665, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Chen, X. [Infrared Processing and Analysis Center, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Dunkley, J. [Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Halpern, M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Jarosik, N.; Page, L.; Spergel, D. N. [Department of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544-0708 (United States); Komatsu, E. [Department of Astronomy, University of Texas, Austin, 2511 Speedway, RLM 15.306, Austin, TX 78712 (United States); Limon, M. [Columbia Astrophysics Lab, Columbia University, Mail Code 5247, 550 W. 120th St., New York, NY 10027 (United States); Meyer, S. S. [Departments of Astrophysics and Physics, KICP and EFI, University of Chicago, Chicago, IL 60637 (United States); Nolta, M. R. [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, University of Toronto, Toronto, ON, Canada M5S 3H8 (Canada); Smith, K. M. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544-1001 (United States); Tucker, G. S., E-mail: bgold@pha.jhu.edu [Department of Physics, Brown University, 182 Hope St., Providence, RI 02912-1843 (United States)

2011-02-01

152

A Search for Transient Microwave Emission from Gamma-Ray Bursts and Other High-Energy Sources Using Archival WMAP Datasets  

NASA Astrophysics Data System (ADS)

We report on a new effort to search the public time-ordered datasets acquired with the Wilkinson Microwave Anisotropy Probe (WMAP) for transient signals associated with gamma-ray bursts (GRBs) and other high-energy cosmic sources. This program is an extension of earlier work in which we searched the archival database of the Differential Microwave Radiometers (DMR) aboard the COBE satellite for microwave transients associated with GRBs. In this previous investigation we demonstrated that the COBE/DMR serendipitously observed a number of GRBs detected with the BATSE instrument aboard the Compton Gamma Ray Observatory (CGRO) and we established the first limits on prompt microwave emission from GRBs. The increased sensitivity and angular resolution of the WMAP radiometers compared to the COBE/DMR lead to a factor of 10,000 improvement in overall point-source sensitivity. Such limits approach the signal levels predicted in the microwave band for the peak prompt emission arising from reverse shocks in GRBs. The detection of prompt microwave emission would provide further insight into burst physics and the physical environments in which bursts occur. We are also searching for transient or flaring signals from active galaxies and similar high-energy sources that are observed in the cumulative WMAP data as "foreground" point sources of microwave emission. We acknowledge partial support for this work through NASA grant NNG05-GN94G.

Stacy, J. G.; Hart, D.; Mbonye, M.; Jackson, P. D.; Winkler, C.

2006-09-01

153

Microwave Emission from the Edgeworth-Kuiper Belt and the Asteroid Belt Constrained from the Wilkinson Microwave Anisotropy Probe  

NASA Astrophysics Data System (ADS)

Objects in the Edgeworth-Kuiper Belt and the main asteroid belt should emit microwaves that may give rise to extra anisotropy signals in the multipole of the cosmic microwave background (CMB) experiment. Constraints are derived from the absence of positive detection of such anisotropies for ell <~ 50, meaning the total mass of Edgeworth-Kuiper Belt objects is smaller than 0.2 M ?. This limit is consistent with the mass extrapolated from the observable population with the size of a >~ 15 km, assuming that the small-object population follows the power law in size dN/da ~ a -q with the canonical index expected for collisional equilibrium, q ~= 3.5, with which 23% of the mass is ascribed to objects smaller than are observationally accessible down to grains. A similar argument applied to the main asteroid belt indicates that the grain population should not increase more quickly than q ~= 3.6 toward smaller radii, if the grain population follows the power law that continues to observed asteroids with larger radii. Both cases are at or only slightly above the limit that can be physically significant, implying the importance of further tightening the CMB anisotropy limit, which may be attained with observation at higher radio frequencies.

Ichikawa, Kazuhide; Fukugita, Masataka

2011-08-01

154

MICROWAVE EMISSION FROM THE EDGEWORTH-KUIPER BELT AND THE ASTEROID BELT CONSTRAINED FROM THE WILKINSON MICROWAVE ANISOTROPY PROBE  

SciTech Connect

Objects in the Edgeworth-Kuiper Belt and the main asteroid belt should emit microwaves that may give rise to extra anisotropy signals in the multipole of the cosmic microwave background (CMB) experiment. Constraints are derived from the absence of positive detection of such anisotropies for l {approx}< 50, meaning the total mass of Edgeworth-Kuiper Belt objects is smaller than 0.2 M{sub +}. This limit is consistent with the mass extrapolated from the observable population with the size of a {approx}> 15 km, assuming that the small-object population follows the power law in size dN/da {approx} a{sup -q} with the canonical index expected for collisional equilibrium, q {approx_equal} 3.5, with which 23% of the mass is ascribed to objects smaller than are observationally accessible down to grains. A similar argument applied to the main asteroid belt indicates that the grain population should not increase more quickly than q {approx_equal} 3.6 toward smaller radii, if the grain population follows the power law that continues to observed asteroids with larger radii. Both cases are at or only slightly above the limit that can be physically significant, implying the importance of further tightening the CMB anisotropy limit, which may be attained with observation at higher radio frequencies.

Ichikawa, Kazuhide; Fukugita, Masataka [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan)

2011-08-01

155

The Cosmic Microwave Background Temperature and Galactic Emission at 8.0 and 8.3 GHz  

NASA Astrophysics Data System (ADS)

We report balloon-borne measurements at 8.0 and 8.3 GHz of Galactic emission and of the radiometric temperature of the cosmic microwave background, the results from the first flight of the ARCADE 2 (Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission) instrument. We find the Galactic free-free emission intensity in the plane to be two-thirds as high as that predicted by a naive extrapolation of 2003 WMAP K-band data, a result consistent with 2006 WMAP findings, and find the Galactic synchrotron emission intensity to be approximately as high as that predicted by a naive interpolation of Haslam all-sky survey and WMAP K-band data. We find TCMB to be 2.90+/-0.12 K at 8.0 GHz and 2.77+/-0.16 K at 8.3 GHz.

Singal, J.; Fixsen, D. J.; Kogut, A.; Levin, S.; Limon, M.; Lubin, P.; Mirel, P.; Seiffert, M.; Wollack, E. J.

2006-12-01

156

Microwave absorption properties and infrared emissivities of ordered mesoporous C-TiO{sub 2} nanocomposites with crystalline framework  

SciTech Connect

Ordered mesoporous C-TiO{sub 2} nanocomposites with crystalline framework were prepared by the evaporation-induced triconstituent co-assembly method. The products were characterized by XRD, TEM, N{sub 2} adsorption-desorption and TG. Their microwave absorption properties were investigated by mixing the product and epoxy resin. It is found that the peak with minimum reflection loss value moves to lower frequencies and the ordered mesoporous C-TiO{sub 2} nanocomposite possesses an excellent microwave absorbing property with the maximum reflection loss of -25.4 dB and the bandwidth lower than -10 dB is 6.6 GHz. The attenuation of microwave can be attributed to dielectric loss and their absorption mechanism is discussed in detail. The mesoporous C-TiO{sub 2} nanocomposites also exhibit a lower infrared emissivity in the wavelength from 8 to 14 {mu}m than that of TiO{sub 2}-free powder. -- Graphical abstract: Ordered mesoporous C-TiO{sub 2} nanocomposite with crystalline framework possess excellent microwave absorbing properties with the maximum reflection loss of -25.4 dB and the bandwidth lower than -10 dB is 6.6 GHz. Display Omitted

Wang, Tao [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); He, Jianping, E-mail: jianph@nuaa.edu.c [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Zhou, Jianhua; Tang, Jing; Guo, Yunxia; Ding, Xiaochun; Wu, Shichao; Zhao, Jianqing [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2010-12-15

157

Impact of conifer forest litter on microwave emission at L-band  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study reports on the utilization of microwave modeling, together with ground truth and L-bank (1.4 GHz) brightness temperatures to investigate the characteristics of conifer forest floor. The microwave data were acquired over natural Virginia pine forest in Maryland by ComRAD, a ground-based mi...

158

Feasibility Study of a Microwave or Far-Infrared Scattering Experiment to Measure Small Scale Turbulence and Anomalous Transport in J.E.T.  

National Technical Information Service (NTIS)

In the first part, we make a rapid review of what can be expected as low frequency turbulence in J.E.T. This is to define the parameters of the density fluctuations which can be expected. A method to deduce the anomalous transport is described. In the sec...

F. Koechlin J. Olivain D. Gresillon A. Truc

1981-01-01

159

Anomalous Diffuse CO2 Emission prior to the January 2002 Short-term Unrest at San Miguel Volcano, El Salvador, Central America  

NASA Astrophysics Data System (ADS)

On January 16, 2002, short-term unrest occurred at San Miguel volcano. A gas-and-steamash plume rose a few hundred meters above the summit crater. An anomalous microseismicity pattern, about 75 events between 7:30 and 10:30 hours, was also observed. Continuous monitoring of CO2 efflux on the volcano started on November 24, 2001, in the attempt to provide a multidisciplinary approach for its volcanic surveillance. The background mean of the diffuse CO2 emission is about 16 g m-2 d-1, but a 17- fold increase, up to 270 g m-2 d-1, was detected on January 7, nine days before the January 2002 short-term unrest at San Miguel volcano. These observed anomalous changes on diffuse CO2 degassing could be related to either a sharp increase of CO2 pressure within the volcanic-hydrothermal system or degassing from an uprising fresh gas-rich magma within the shallow plumbing system of the volcano since meteorological fluctuations cannot explain this observed increase of diffuse CO2 emission.

Pérez, Nemesio M.; Hernández, Pedro A.; Padrón, Eleazar; Cartagena, Rafael; Olmos, Rodolfo; Barahona, Francisco; Melián, Gladys; Salazar, Pedro; López, Dina L.

2006-04-01

160

SEARCH FOR HIGH-ENERGY GAMMA-RAY EMISSION FROM AN ANOMALOUS X-RAY PULSAR, 4U 0142+61  

SciTech Connect

Until 2004, anomalous X-ray pulsars (AXPs) were known as strong emitters of soft X-rays only (<10 keV). The discovery of hard X-ray component from AXPs provided important insight about their emission properties while it posed a serious challenge to explain its origin. The physical mechanism of the hard emission component has still not been fully resolved. We investigate the high-energy gamma-ray properties of the brightest AXP, 4U 0142+61, using data collected with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope to establish the spectral behavior of the source on a very broad energy span and search for pulsed emission. Here, we present our results of detailed search for the persistent and pulsed high-energy gamma-ray emission from 4U 0142+61 which result in no significant detection. However, we obtain upper limits to the persistent high-energy gamma-ray emission flux which helps us to constrain existing physical models.

Sasmaz Mus, Sinem; Goegues, Ersin, E-mail: sinemsm@sabanciuniv.ed, E-mail: ersing@sabanciuniv.ed [Sabanci University, Faculty of Engineering and Natural Sciences, Orhanli-Tuzla 34956, Istanbul (Turkey)

2010-11-01

161

The Effects of Layers in Dry Snow on Its Passive Microwave Emissions Using Dense Media Radiative Transfer Theory Based on the Quasicrystalline Approximation (QCA\\/DMRT)  

Microsoft Academic Search

A model for the microwave emissions of multilayer dry snowpacks, based on dense media radiative transfer (DMRT) theory with the quasicrystalline approximation (QCA), provides more accurate results when compared to emissions determined by a homogeneous snowpack and other scattering models. The DMRT model accounts for adhesive aggregate effects, which leads to dense media Mie scattering by using a sticky particle

Ding Liang; Xiaolan Xu; Leung Tsang; Konstantinos M. Andreadis; Edward G. Josberger

2008-01-01

162

Monitor the microwave thermal emission anomaly around the Yushu earthquake fault zone by using AMSR-E data  

Microsoft Academic Search

Earthquake is caused by collision and compression of lithosphere plates. It has been found that during rock failure under lithosphere plate compression, some anomalies of thermal emission at certain frequencies, e.g. 300MHz, 2GHz and 22GHz, might be observed. Satellite-borne AMSR-E (Advanced Microwave Scanning Radiometer-EOS) has dual-polarized 12 channels (6.925, 10.65, 18.7, 23.8, 36.5 and 89GHz), where two channels, 18.7 and

Hao Chen; Yaqiu Jin

2010-01-01

163

Emission of diacetyl (2,3 butanedione) from natural butter, microwave popcorn butter flavor powder, paste, and liquid products.  

PubMed

Diacetyl (2,3 butanedione), a butter-flavored diketone, has been linked to a severe lung disease, bronchiolitis obliterans. We tested a total of three natural butters and artificial microwave popcorn butter flavorings (three powders, two pastes, and one liquid) for bulk diacetyl concentration and diacetyl emissions when heated. Pastes and liquid butter flavors contained the highest amount (6% to 10.6%) while natural butter possessed up to 7500 times less diacetyl. All artificial butter flavors studied emitted diacetyl. Dry powders emitted up to 1.62 ppm diacetyl; wetted powders up to 54.7 ppm diacetyl; and pastes emitted up to 34.9 ppm diacetyl. The liquid butter flavor emitted up to 17.2 ppm diacetyl. Microwave popcorn flavoring mixtures emitted up to 11.4 ppm diacetyl. At least 93% of the dry powder particles were inhalable. These studies show that microwave butter flavoring products generate concentrations of diacetyl in the air great enough to endanger those exposed. PMID:20662421

Rigler, Mark W; Longo, William E

164

Anomalous magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

Anomalous symmetries induce currents which can be parallel rather than orthogonal to the hypermagnetic field. Building on the analogy of charged liquids at high magnetic Reynolds numbers, the persistence of anomalous currents is scrutinized for parametrically large conductivities when the plasma approximation is accurate. Different examples in globally neutral systems suggest that the magnetic configurations minimizing the energy density with the constraint that the helicity be conserved coincide, in the perfectly conducting limit, with the ones obtainable in ideal magnetohydrodynamics where the anomalous currents are neglected. It is argued that this is the rationale for the ability to extend to anomalous magnetohydrodynamics the hydromagnetic solutions characterized by finite gyrotropy. The generally covariant aspects of the problem are addressed with particular attention to conformally flat geometries which are potentially relevant for the description of the electroweak plasma prior to the phase transition.

Giovannini, Massimo

2013-09-01

165

Microwave remediation of electronic circuitry waste and the resulting gaseous emissions  

NASA Astrophysics Data System (ADS)

The global community has become increasingly dependent on computer and electronic technology. As a result, society is faced with an increasing amount of obsolete equipment and electronic circuitry waste. Electronic waste is generally disposed of in landfills. While convenient, this action causes a substantial loss of finite resources and poses an environmental threat as the circuit board components breakdown and are exposed to the elements. Hazardous compounds such as lead, mercury and cadmium may leach from the circuitry and find their way into the groundwater supply. For this dissertation, a microwave waste remediation system was developed. The system was designed to remove the organic components from a wide variety of electronic circuitry. Upon additional heating of the resulting ash material in an industrial microwave, a glass and metal product can be recovered. Analysis of the metal reveals the presence of precious metals (gold, silver) that can be sold to provide a return on investment. a glass and metal product can be recovered. Analysis of the metal reveals the presence of precious metals (gold, silver) that can be sold to provide a return on investment. Gaseous organic compounds that were generated as a result of organic removal were treated in a microwave off gas system that effectively reduced the concentration of the products emitted by several orders of magnitude, and in some cases completely destroying the waste gas. Upon further heating in an industrial microwave, a glass and metal product were recovered. In order to better understand the effects of processing parameters on the efficiency of the off-gas system, a parametric study was developed. The study tested the microwave system at 3 flow rates (10, 30, and 50 ft 3/min) and three temperatures (400, 700 and 1000°C. In order to test the effects of microwave energy, the experiments were repeated using a conventional furnace. While microwave energy is widely used, the mechanisms of interaction with materials is not well understood. In an effort to better understand how microwaves couple with materials, a newly developed molecular orbital model was investigated. The model proposed an interaction mechanism associated with the development of coupled oscillators upon application of microwave energy. The model was used to model several of the waste gases that appear in the waste stream. Results from experimentation support the data generated thus far.

Schulz, Rebecca L.

166

Constraints on spinning dust towards Galactic targets with the VSA: a tentative detection of excess microwave emission towards 3C396  

Microsoft Academic Search

We present results from observations made at 33 GHz with the Very Small Array\\u000a(VSA) telescope towards potential candidates in the Galactic plane for spinning\\u000adust emission. In the cases of the diffuse HII regions LPH96 and NRAO591 we\\u000afind no evidence for anomalous emission and, in combination with Effelsberg\\u000adata at 1.4 and 2.7 GHz, confirm that their spectra

Anna Scaife; David A. Green; Richard A. Battye; Rod D. Davies; Richard J. Davis; Clive Dickinson; Thomas Franzen; Keith Grainge; Yaser A. Hafez; Michael P. Hobson; Anthony Lasenby; Guy G. Pooley; Nutan Rajguru; Rafael Rebolo; Jos ´ e; Alberto Rubi; Richard D. E. Saunders; Paul F. Scott; David Titterington; Elizabeth Waldram; Robert A. Watson

2007-01-01

167

The heating of the upper solar atmosphere and variations of microwave emission from the active region NOAA 0139  

NASA Astrophysics Data System (ADS)

The evolution and structure of the active region NOAA 0139 on the basis of radio observations obtained at RATAN-600, SSRT, and RT-22 are investigated. By means of a wavelet analysis as well as images obtained at the space orbital stations SOHO and TRACE, it is shown that observed dynamics of the S-component of microwave emission may be caused by the change of number and power of elementary flare events. The strong depression of emission revealed at short wavelengths in the course of evolution of active region is explained by the decrease of fluxes of accelerated electrons, which are responsible for the high temperature of the transition region and upper chromosphere of the Sun. The results obtained show evidence for an essential contribution of elementary flare events to the heating of the coronal plasma.

Tsap, Yu. T.; Tsvetkov, L. I.; Yurovskii, Yu. F.; Peterova, N. G.; Borisevich, T. P.; Agalakov, B. V.

2006-10-01

168

Gas temperature measurements in a microwave plasma by optical emission spectroscopy under single-wall carbon nanotube growth conditions  

NASA Astrophysics Data System (ADS)

Plasma gas temperatures were measured via in situ optical emission spectroscopy in a microwave CH4-H2 plasma under carbon nanotube (CNT) growth conditions. Gas temperature is an important parameter in controlling and optimizing CNT growth. The temperature has a significant impact on chemical kinetic rates, species concentrations and CNT growth rates on the substrate. H2 rotational temperatures were determined from the Q-branch spectrum of the d\\,^{3}\\Pi _u(0)\\to a\\,^{3}\\Sigma ^{+}_g (0) transition. N2 rotational and vibrational temperatures were measured by fitting rovibrational bands from the N2 emission spectrum of the C 3?u ? B 3?g transition. The N2 rotational temperature, which is assumed to be approximately equal to the translational gas temperature, increases with an increase in input microwave plasma power and substrate temperature. The measured H2 rotational temperatures were not in agreement with the measured N2 rotational temperatures under the CNT growth conditions in this study. The measured N2 rotational temperatures compared with the H2 rotational temperatures suggest the partial equilibration of upper excited state due to higher, 10 Torr, operating pressure. Methane addition in the hydrogen plasma increases the gas temperature slightly for methane concentrations higher than 10% in the feed gas.

Garg, R. K.; Anderson, T. N.; Lucht, R. P.; Fisher, T. S.; Gore, J. P.

2008-05-01

169

Characterization of near-infrared nonmetal atomic emission from an atmospheric helium microwave-induced plasma using a Fourier transform spectrophotometer  

SciTech Connect

A new approach for using Fourier transform spectroscopy (FTS) for the detection of atomic emission from an atmospheric helium plasma has been developed and the results obtained are described. Among the different types of plasma source available, the atmospheric pressure microwave helium plasma appears to be an efficient excitation source for the determination of nonmetal species. The more complete microwave plasma emission spectra of Cl, Br, I, S, O, P, C, N, and He in the near-infrared region were obtained and their corrected relative emission intensities are reported. This makes qualitative identification simple, and aids in the quantitative analysis of atomic species. The accuracy of the emission wavelengths obtained with the Fourier transform spectrophotometer was excellent and the resolution provided by the FTS allowed certain adjacent emission lines to be adequate for analytical applications.

Hubert, J.; Van Tra, H.; Chi Tran, K.; Baudais, F.L.

1986-08-01

170

Field emission from bias-grown diamond thin films in a microwave plasma  

DOEpatents

A method of producing diamond or diamond like films in which a negative bias is established on a substrate with an electrically conductive surface in a microwave plasma chemical vapor deposition system. The atmosphere that is subjected to microwave energy includes a source of carbon, nitrogen and hydrogen. The negative bias is maintained on the substrate through both the nucleation and growth phase of the film until the film is continuous. Biases between -100V and -200 are preferred. Carbon sources may be one or more of CH.sub.4, C.sub.2 H.sub.2 other hydrocarbons and fullerenes.

Gruen, Dieter M. (Downers Grove, IL); Krauss, Alan R. (Naperville, IL); Ding, Ming Q. (Beijing, CN); Auciello, Orlando (Bolinbrook, IL)

2002-01-01

171

Tunable one-dimensional microwave emissions from cyclic-transition three-level artificial atoms  

SciTech Connect

By strongly driving a cyclic-transition three-level artificial atom, demonstrated by such as a flux-based superconducting circuit, we show that coherent microwave signals can be excited along a coupled one-dimensional transmission line. Typically, the intensity of the generated microwave is tunable via properly adjusting the Rabi frequencies of the applied strong-driving fields or introducing a probe field with the same frequency. In practice, the system proposed here could work as an on-chip quantum device with controllable atom-photon interaction to implement a total-reflecting mirror or switch for the propagating probe field.

Jia, W. Z. [Quantum Optoelectronics Laboratory, School of Physics and Technology, Southwest Jiaotong University, Chengdu 610031 (China); Wei, L. F. [Quantum Optoelectronics Laboratory, School of Physics and Technology, Southwest Jiaotong University, Chengdu 610031 (China); State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Wang, Z. D. [Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong, Pokfulam Road (Hong Kong)

2011-02-15

172

A Noncoherent Model for Microwave Emissions and Backscattering from the Sea Surface  

Microsoft Academic Search

The two-scale (small irregularities superimposed on large undulations) scattering theory proposed by Semyonov has been extended and used to compute the microwave apparent temperature and the backscattering cross section from ocean surfaces. The effect of the small irregularities on the scattering characteristics of the large undulations is included by modifying the Fresnel reflection coefficients, and the effect of the large

S. T. Wu; A. K. Fung

1972-01-01

173

The field emission of vacuum filtered graphene films reduced by microwave  

Microsoft Academic Search

A green, convenient, and inexpensive approach to producing graphene field emitters has been developed. Graphite oxide (GO) produced by hummer method was reduced to graphene in a microwave synthesis system. The vacuum filtration method made it possible to form pure and uniform graphene thin films without any additives and it's easy to transfer to other substrates. Transmission electron microscopy (TEM),

Kai Wang; Tao Feng; Min Qian; Hui Ding; Yiwei Chen; Zhuo Sun

2011-01-01

174

Field emission from patterned carbon nanotube emitters produced by microwave plasma chemical vapor deposition  

Microsoft Academic Search

Large area carbon nanotube patterns were fabricated by microwave plasma chemical vapor deposition. The carbon nanotubes were grown on pre-patterned catalyst films. Scanning electron microscopy and Raman spectroscopy were used to characterize the structure of the carbon nanotubes. The carbon nanotubes were very uniform and approximately 100 nm in diameter. The Raman spectrum shows a good graphitization for the carbon

J Yu; Q Zhang; J Ahn; S. F Yoon; Rusli; Y. J Li; B Gan; K Chew; K. H Tan

2001-01-01

175

Direct determination of cadmium in solids using a capacitively coupled microwave plasma atomic emission spectrometer  

Microsoft Academic Search

A capacitively coupled microwave plasma (CMP) operating at 800 W was examined for the direct determination of cadmium in solids. The laboratory-constructed system contained a tungsten cup electrode capable of holding microsample quantities. A low-powered plasma was used to heat the sample, while at higher powers the plasma was used for sample vaporization and excitation. This plasma enabled thermal vaporization

Andrea M. Pless; Andrea Croslyn; Mary Jane Gordon; Benjamin W. Smith; James D. Winefordner

1997-01-01

176

Microwave Radiometer (MWR) Handbook  

SciTech Connect

The Microwave Radiometer (MWR) provides time-series measurements of column-integrated amounts of water vapor and liquid water. The instrument itself is essentially a sensitive microwave receiver. That is, it is tuned to measure the microwave emissions of the vapor and liquid water molecules in the atmosphere at specific frequencies.

Morris, VR

2006-08-01

177

High-power coherent microwave emission from magnetic tunnel junction nano-oscillators with perpendicular anisotropy.  

PubMed

The excitation of the steady-state precessions of magnetization opens a new way for nanoscale microwave oscillators by exploiting the transfer of spin angular momentum from a spin-polarized current to a ferromagnet, referred to as spin-transfer nano-oscillators (STNOs). For STNOs to be practical, however, their relatively low output power and their relatively large line width must be improved. Here we demonstrate that microwave signals with maximum measured power of 0.28 ?W and simultaneously narrow line width of 25 MHz can be generated from CoFeB-MgO-based magnetic tunnel junctions having an in-plane magnetized reference layer and a free layer with strong perpendicular anisotropy. Moreover, the generation efficiency is substantially higher than previously reported STNOs. The results will be of importance for the design of nanoscale alternatives to traditional silicon oscillators used in radio frequency integrated circuits. PMID:22663148

Zeng, Zhongming; Amiri, Pedram Khalili; Krivorotov, Ilya N; Zhao, Hui; Finocchio, Giovanni; Wang, Jian-Ping; Katine, Jordan A; Huai, Yiming; Langer, Juergen; Galatsis, Kosmas; Wang, Kang L; Jiang, Hongwen

2012-06-11

178

Determination of heavy metals in soils and sediments by microwave-assisted digestion and inductively coupled plasma optical emission spectrometry analysis  

Microsoft Academic Search

The determination of the total content and the leachable aliquot by aqua regia dissolution of eight heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) in soils and sediments was developed by microwave digestion technique combined with inductively coupled plasma atomic emission spectrometry. A complete digestion of soils and sediments was achieved by using an acid mixture of

M Bettinelli; G. M Beone; S Spezia; C Baffi

2000-01-01

179

A large scale microwave emission model for forests. Contribution to the SMOS algorithm  

Microsoft Academic Search

1. INTRODUCTION It is well known that surface soil moisture plays an important role in the water cycle and the global climate. SMOS is a L-Band multi-angle dual-polarization microwave radiometer for global monitoring of this variable. In the areas covered by forests, the opacity is relatively high, and the knowledge of moisture remains problematic. A significant percentage of SMOS pixels

R. Rahmoune; A. Della Vecchia; P. Ferrazzoli; L. Guerriero; F. Martin-Porqueras

2009-01-01

180

Application of a plane-stratified emission model to predict the effects of vegetation in passive microwave radiometry  

NASA Astrophysics Data System (ADS)

This paper reports the application to vegetation canopies of a coherent model for the propagation of electromagnetic radiation through a stratified medium. The resulting multi-layer vegetation model is plausibly realistic in that it recognises the dielectric permittivity of the vegetation matter, the mixing of the dielectric permittivities for vegetation and air within the canopy and, in simplified terms, the overall vertical distribution of dielectric permittivity and temperature through the canopy. Any sharp changes in the dielectric profile of the canopy resulted in interference effects manifested as oscillations in the microwave brightness temperature as a function of canopy height or look angle. However, when Gaussian broadening of the top and bottom of the canopy (reflecting the natural variability between plants) was included within the model, these oscillations were eliminated. The model parameters required to specify the dielectric profile within the canopy, particularly the parameters that quantify the dielectric mixing between vegetation and air in the canopy, are not usually available in typical field experiments. Thus, the feasibility of specifying these parameters using an advanced single-criterion, multiple-parameter optimisation technique was investigated by automatically minimizing the difference between the modelled and measured brightness temperatures. The results imply that the mixing parameters can be so determined but only if other parameters that specify vegetation dry matter and water content are measured independently. The new model was then applied to investigate the sensitivity of microwave emission to specific vegetation parameters.

Lee, K.; Chawn Harlow, R.; Burke, E. J.; Shuttleworth, W. J.

181

Long period oscillations of microwave emission of solar active regions: observations with NoRH and SSRT  

NASA Astrophysics Data System (ADS)

In this work we present the first results of study and comparison of the parameters of quasi-periodic long-term oscillations of microwave emission of large (>0.7 arcmin) sunspots as a result of simultaneous observations with two radioheliographs - NoRH (17 GHz) and Siberian Solar Radio Telescope (SSRT) (5.7 GHz) with 1 minute cadence. Radioheliographs have been working with quite large time overlap (about 5 hours) and have the high spatial resolution: 10 arcsec (NoRH) and 20 arcsec (SSRT). We have found that quasi-periodic long-term oscillations are surely observed at both frequencies with the periods in the range of 20-150 min. We detected common periods for common time of observations with two radioheliographs and interpret this as the consequence of the vertical-radial quasi-periodic displacements of sunspot as a whole structure.

Bakunina, I. A.; Abramov-Maximov, V. E.; Lesovoy, S. V.; Shibasaki, K.; Solov'ev, A. A.; Tikhomirov, Yu. V.

2009-03-01

182

Design of red/green emissive lanthanide activated nano-materials by supersonic and microwave co-irradiations  

NASA Astrophysics Data System (ADS)

ZnSnO3:Eu3+ and Sr1-xCaxMoO4:Tb3+ nanocrystals with controlled shape have been assembled in the presence of two driving forces (supersonic microwave co-assistance, abbreviated as SMC) simultaneously in less than 60 min at very low temperature (80 °C). Scanning Electronic Microscope (SEM) images further supported the existence of cubic crystals and shuttle-like structures. More interestingly, Eu(III) ion has been encapsulated into zinc stannate for the first time and ZnSnO3:Eu3+ can exhibit red emissions excited by long wavelength (395 nm). Similarly, it was found that Sr1-xCaxMoO4:Tb3+ had striking green luminescence. The parameters to improve the optical properties have been studied in detail. This convenient approach may be applicable to construct other phosphors with well-defined crystalline structures.

Wang, Qianming; Huo, Jiansheng; Zheng, Yuhui; Pang, Shuting; He, Zhouzhi

2013-04-01

183

Manifestation of large-scale kink oscillations of coronal loops in the low frequency modulations of solar microwave emission  

NASA Astrophysics Data System (ADS)

Very-low-frequency fluctuations (¡ 0.01 Hz) of solar microwave radiation were analysed by means of a "sliding window" Fourier transform combined with the Wigner-Ville technique. In view of the fact that slow variations of the magnetic field in the radiation source, as well as a large-scale motion of the source, can modulate the intensity of the received radio signal, we considered large-scale kink-type oscillatory motions of coronal loops which were accompanied also by periodic magnetic stress, created near the loops footpoints during each inclination of loop, i.e. two times per the oscillation cycle. In such cases a properly located observer, besides of the modulation caused by motion of the emission diagram pattern at the main oscillation frequency, may see also modulation at a double frequency of the loop oscillation as well as much weaker higher harmonics. Therefore, the presence in the very-low-frequency spectra of the lines at the main and double frequency of the loop oscillation ("modulation pairs") may indicate about a kink-type oscillatory dynamics of the loop. Special attention in the present study has been paid to the analysis of modulations of microwave emission recorded at the same time when TRACE EUV telescope observed large scale oscillations of coronal loops. The applied data analysis technique, besides of the modulations connected with loop kink oscillations seen by TRACE, enables to detect also the modulations associated with kink oscillations of smaller (invisible for TRACE) loops. Acknowledgements: MLK and TZ acknowledge Austrian Fond zur Fürderung der wissenschaftlichen Forschung (project P21197-N16); MP and HOR acknowledge Austrian Fond zur Fürderung der wissenschaftlichen Forschung (project P20680-N16).

Khodachenko, Maxim; Kislyakova, Kristina; Zaqarashvili, Teimuraz; Kislyakov, Albert; Panchenko, Mykhaylo; Zaitsev, Valerii; Rucker, Helmut

184

Anomalous Change of Diffuse CO2 Emission Rates at San Salvador volcano, El Salvador, Central America: a premonitory geochemical signature of magmatic and/or tectonic reactivation?  

NASA Astrophysics Data System (ADS)

San Salvador volcano is located towards the southern part of the Central American graben. The most recent magmatic activity was mainly focused on the volcano NW flank forming monogenetic explosion craters, cinder cones, and lava flows. Flank vents continue to erupt at a rate of once every 82 yrs with the last eruption in 1917 (Sofield, 1999). The city of San Salvador, with a population 1.7 million located at the skirts of the volcano, will be at high risk if an eruption occurs. The purpose of this work is to provide a multidisciplinary approach for the volcanic surveillance by means of introducing geochemical continuous monitoring of diffuse CO2 and H2S emission rates. Soil CO2 and H2S efflux are continuously monitored at Cerro La Hoya, which is located at San Salvador volcano southern flank, by means of a soil gas efflux continuous monitoring station. Since Nov.11, 2001, until Aug.30, 2002, about 6,800 observations of soil gas efflux and meteorological measurements had been recorded. Soil H2S efflux values were negligible during this period. On the contrary, two distinct diffuse CO2 degassing periods have been observed: (1) a stationary period from Nov. 11 to Dec. 27, 2001, and (2) a clear increasing trend period from Dec. 28, 2001, up to date. From Nov.11 to Dec.27, 2001, CO2 efflux showed an average of 700 gm-2d-1 peaking values up to 1,194 gm-2d-1. From Dec.28, 2001, to Aug.30, 2002, CO2 efflux showed an average of 7,435 gm-2d-1 peaking values up to 45,285 gm-2d-1. Soil temperature showed similar average and peak values for both periods. It is quite evident that this anomalous change of CO2 efflux rate at San Salvador is not driven by meteorological fluctuations. Therefore, this anomalous change of diffuse CO2 emission should be related to an increase of CO2 pressure in the volcanic-hydrothermal system. This increase of fluid pressure could be related to subsurface strain/stress changes, which might be taking place due to either magmatic or tectonic reactivation in the study area.

Perez, N.; Salazar, J.; Hernandez, P.; Soriano, T.; Barahona, F.; Cartagena, R.; Olmos, R.; Lopez, D.

2002-12-01

185

Improvement of Satellite Data Assimilation with Updated Microwave Land Emissivity Model in CRTM and New Momentum and Thermal Roughness Lengths in GFS  

NASA Astrophysics Data System (ADS)

Satellite radiances (infrared and microwave) measure upwelling radiation at the top of atmosphere and being increasingly used for weather and climate prediction systems. Most satellite radiance measurements in various spectral channels are assimilated as radiances through the JCSDA Community Radiative Transfer Model (CRTM) on the NCEP Gridpoint Statistical Interpolation (GSI). It is noticed that the amount of satellite data assimilated over land in the GSI is far less than over ocean. In terms of microwave sensors, there are two major factors resulting in large errors in simulated satellite brightness temperatures over land and rejection of satellite data in GSI, especially for surface or near surface sensitive channels. One is the inaccurate surface emissivity calculation in the CRTM and the other is much larger bias in the NCEP operational Global Forecast System (GFS) predicted land surface skin temperature (LST) over desert and arid regions during daytime in the warm season. This study focuses on improvement of the microwave land emissivity model developed by Weng et al. (2001), which is applied for all microwave sensors in the CRTM. We add soil and vegetation characteristics as well as canopy optical information in the emissivity model. The alternative vegetation-dependent formulations of momentum and thermal roughness lengths are utilized to reduce the large cold bias of daytime LST over desert and arid regions in the GFS. The NOAA 18 Advanced Microwave Sounding Unit-A (AMSU-A), which has a multi-channel microwave temperature/humidity sounder, is selected to investigate brightness temperature simulation with the improved schemes. The GFS/GSI full cycle runs are performed, in which the GFS model forecast provides a background for an analysis of GSI, and then the analysis is used as the initial conditions for subsequent forecasts and the cycle continues.

Zheng, W.; Ek, M. B.; Derber, J.; Wei, H.; Meng, C. J.

2010-12-01

186

Observation of Anomalously Large Spectral Bandwidth in a High-Gain Self-Amplified Spontaneous Emission Free-Electron Laser  

Microsoft Academic Search

Observation of ultra-wide bandwidth, up to a full width of 15%, high-gain operation of a self- amplified spontaneous emission free-election laser (SASE FEL) is reported. This type of lasing is obtained with a strongly chirped beam (?E\\/E ? 1.7%) emitted from the accelerator. Because of non- linear pulse compression during beam transport, a short, high current pulse with strong mismatch

G. Andonian; A. Murokh; J. B. Rosenzweig; R. Agustsson; M. Babzien; I. Ben-Zvi; P. Frigola; J. Y. Huang; L. Palumbo; C. Pellegrini; S. Reiche; G. Travish; C. Vicario; V. Yakimenko

187

The Air Microwave Yield (AMY) experiment to measure the GHz emission from air shower plasmas  

NASA Astrophysics Data System (ADS)

The AMY experiment aims to measure the Microwave Bremsstrahlung Radiation (MBR) emitted by air-showers secondary electrons accelerating in collisions with neutral molecules of the atmosphere. The measurements are performed at the Beam Test Facility (BTF) of Frascati INFN National Laboratories and the final purpose is to characterize the process to be used in a next generation detectors of ultra-high energy cosmic rays (up to 1020eV). We describe the experimental set-up and the first test measurement performed in November 2011.

Alvarez-Muñiz, J.; Bohacova, M.; Cataldi, G.; Coluccia, M. R.; Creti, P.; De Mitri, I.; Di Giulio, C.; Engel, R.; Facal San Luis, P.; Iarlori, M.; Martello, D.; Monasor, M.; Perrone, L.; Petrera, S.; Privitera, P.; Riegel, M.; Rizi, V.; Rodriguez Fernandez, G.; Salamida, F.; Salina, G.; Settimo, M.; Smida, R.; Verzi, V.; Werner, F.; Williams, C.

2013-06-01

188

Soft X-ray, microwave, and hard X-ray emission from a solar flare - Implications for electron heating and acceleration in current channels  

NASA Astrophysics Data System (ADS)

The soft X-ray, microwave, and hard X-ray emissions from the solar flare of May 14, 1980 are studied. The flare consists of a gradual component in soft X-rays and microwaves and a superposed impulsive burst accompanied by hard X-ray emission. The impulsive phase of the flare appears in the soft X-ray emission as a temperature spike and as an increased rate of energy dissipation into the plasma. A new, spatially and spectrally distinct, microwave component appears during the impulsive burst. The data are interpreted in terms of Joule heating and the electric field acceleration of electrons in one or more current sheets. It is found that all three emissions can be generated with sub-Dreicer electric fields. The soft X-ray emitting plasma can be heated by a single current sheet only if the resistivity in the sheet is well above the classical, collisional resistivity. Conditions are also given for the hard X-ray emission to be from nonthermal electrons with classical resistivity.

Holman, Gordon D.; Kundu, Mukul R.; Kane, Sharad R.

1989-10-01

189

Determination of polychlorinated biphenyls in biotic matrices using gas chromatography--microwave-induced plasma atomic emission spectrometry.  

PubMed

Basic parameters associated with practical application of gas chromatography coupled with microwave-induced plasma atomic emission spectrometric detection GC-MIP-AED in the determination of seven "indicator" polychlorinated biphenyls (PCBs) in biotic matrices were evaluated. The detection limit for chlorine (Cl-479) was found to be 0.54 pg/s. Under the conditions used for sample analysis (1 microliters of purified extract injected into the GC-MIP-AED system represented 2.5 mg of original fat), this value corresponded approximately to 0.15 mg/kg of the respective congeners in fat. The detector response was linear within the tested range of 0.5-10 ng of each injected PCB. The relative standard deviation of repeated injections for the lowest concentration level of 0.5 ng of PCB per injection ranged between 10.5 and 34.4% depending on the chlorine content of the individual analytes. The results demonstrate a high selectivity of chlorine detection. Carbon (C-496) chromatograms recorded simultaneously demonstrated the efficiency of the clean-up step used. Quantitative results (analytes at levels of 0.1-1 mg/kg) obtained with the atomic emission detector did not differ significantly from those recorded with a conventional electron-capture detector. PMID:7757209

Hajslová, J; Cuhra, P; Kempný, M; Poustka, J; Holadová, K; Kocourek, V

1995-05-01

190

Direct determination of several elements in MIBK extract by high-power nitrogen-oxygen mixed gas microwave-induced plasma optical emission spectrometry.  

PubMed

A nitrogen-oxygen mixed gas microwave-induced plasma with an Okamoto cavity was employed as an atomization and excitation source for emission spectrometric analysis of organic solvent samples. Nitrogen-oxygen mixed gas produces very a stable microwave-induced plasma that is highly robust to the loading of 4-methyl-2-pentanone (MIBK), possibly because the organic solvent is completely combusted in the oxygen-containing plasma. After extracting test solutions containing Al, Co, Cr(III), Cu, Fe(III), Mo(VI), Ni, Pb with MIBK, both the aqueous phase and the organic phase were aspirated into the microwave-induced plasma, yielding linear calibration curves for both the species in the aqueous phase (Al, Co, Cr, Ni, and Pb) and those in the organic phase (Fe and Mo). These results indicate that Fe and Mo can be extracted with MIBK, which is explained by the partition coefficients of these elements in MIBK. PMID:15931498

Maeda, Tetsuo; Wagatsuma, Kazuaki; Okamoto, Yukio

2005-06-02

191

Constraints on spinning dust towards Galactic targets with the Very Small Array: a tentative detection of excess microwave emission towards 3C396  

NASA Astrophysics Data System (ADS)

We present results from observations made at 33 GHz with the Very Small Array (VSA) telescope towards potential candidates in the Galactic plane for spinning dust emission. In the cases of the diffuse HII regions LPH96 and NRAO591 we find no evidence for anomalous emission and, in combination with Effelsberg data at 1.4 and 2.7GHz, confirm that their spectra are consistent with optically thin free-free emission. In the case of the infrared bright supernova remnant 3C396 we find emission inconsistent with a purely non-thermal spectrum and discuss the possibility of this excess arising from either a spinning dust component or a shallow spectrum pulsar wind nebula, although we conclude that the second case is unlikely given the strong constraints available from lower-frequency radio images.

Scaife, Anna; Green, David A.; Battye, Richard A.; Davies, Rod D.; Davis, Richard J.; Dickinson, Clive; Franzen, Thomas; Génova-Santos, Ricardo; Grainge, Keith; Hafez, Yaser A.; Hobson, Michael P.; Lasenby, Anthony; Pooley, Guy G.; Rajguru, Nutan; Rebolo, Rafael; Rubiño-Martin, José Alberto; Saunders, Richard D. E.; Scott, Paul F.; Titterington, David; Waldram, Elizabeth; Watson, Robert A.

2007-05-01

192

Microwave emission from X-ray bright solar-like stars: the F-G main sequence and beyond.  

NASA Astrophysics Data System (ADS)

A sample of F and G main sequence stars and slightly evolved F and G stars, selected as the apparently strongest X-ray sources in their class as detected in the ROSAT All-Sky Survey (RASS), has been observed in microwaves to search for coronae with strong heating and populations of nonthermal particles. The microwave flux densities were observed with the VLA at 8.4GHz. Radio emission has been detected from nine targets, in both luminosity classes V and IV. Since known or unknown cool companions in binary systems may cause spurious results, we have checked the available spectroscopic and astrometric data, including unpublished CORAVEL observations. There is at least one detected object in each of the four spectral and luminosity classes of stars, FIV, FV, GIV, and GV for which no known companion can be made responsible for the observed emission. A very luminous X-ray and radio source is identified with the F0 V star HD 12230, a member of the Pleiades Moving Group with an age of the order of 50-70Myr. HD 129333 (EK Dra), a G0 V target presumably of the same age, is detected also, and the X-ray and radio modulations agree with the optically measured rotation. On the other hand, three very old stars that are leaving the main sequence and are moving towards the subgiant luminosity class are found to be strong X-ray and radio emitters; in the case of HD 20010, an F8 IV star, the hypothetical existence of an unknown spectroscopic companion would contradict astrometric data. These stars appear to define a new class of radio-luminous coronal stars. The observed microwave flux densities agree with the ratio of radio to X-ray fluxes of other active coronal stars. We report sensitive upper limits for all non-detections, up to an order of magnitude lower than in previous surveys. These observations yield first systematic evidence that stars close to the solar spectral type can maintain considerable nonthermal electron populations in their coronae, possibly due to a mechanism that involves coronal heating. They provide the crucial link between the study of the solar corona and of active coronal stars (the "solar-stellar connection"), and bridge the remaining gaps on the radio main sequence between the cooler stars and chemically peculiar Ap stars. Further, they support the view that young, near-Zero-Age Main-Sequence (ZAMS) stars are able to continually produce luminous radio emission after their arrival on the ZAMS. The strong activity resurgence in the sample of old stars moving off the main sequence may be related to an increase in convective turnover time as the internal structuring of the stars changes; this is of potential interest for the study of the stellar interior of evolved stars.

Guedel, M.; Schmitt, J. H. M. M.; Benz, A. O.

1995-10-01

193

Connecting surface emissions, convective uplifting, and long-range transport of carbon monoxide in the upper troposphere: New observations from the Aura Microwave Limb Sounder  

NASA Astrophysics Data System (ADS)

Two years of observations of upper tropospheric (UT) carbon monoxide (CO) from the Aura Microwave Limb Sounder are analyzed; in combination with the CO surface emission climatology and data from the NCEP analyses. It is shown that spatial distribution, temporal variation and long-range transport of UT CO are closely related to the surface emissions, deep-convection and horizontal winds. Over the Asian monsoon region, surface emission of CO peaks in boreal spring due to high biomass burning in addition to anthropogenic emission. However, the UT CO peaks in summer when convection is strongest and surface emission of CO is dominated by anthropogenic source. The long-range transport of CO from Southeast Asia across the Pacific to North America, which occurs most frequently during boreal summer, is thus a clear imprint of Asian anthropogenic pollution influencing global air quality.

Jiang, Jonathan H.; Livesey, Nathaniel J.; Su, Hui; Neary, Lori; McConnell, John C.; Richards, Nigel A. D.

2007-09-01

194

On the asymmetry of the solar bipolar active regions from the phenomenon of the sign change of the microwave circular polarized emission  

NASA Astrophysics Data System (ADS)

Using one-dimensional scans of the polarization distribution of the microwave emission in solar active regions, as obtained at the Siberian Solar Radio Telescope it is shown that the phenomenon of sign inversion of the circular polarization of the microwave emission at a wavelength of 5.2 cm from bipolar groups has a west asymmetry when the group passes the central meridian (CM) of the Sun. This probably means that the axis of the symmetry of the magnetic field for a typical bipolar group is inclined to the east limb of the Sun so that the following wing of each loop is more inclined with respect to the horizontal than the preceding wing. Analysis of 77 active regions showed that this phenomenon had a tendency to be symmetrical relative to the CM or to have an east asymmetry under an increasing level of X-ray activity.

Bakunina, I. A.

2003-06-01

195

Frequency and Angular Variations of Land Surface Microwave Emissivities: Can we Estimate SSM/T and AMSU Emissivities from SSM/I Emissivities.  

National Technical Information Service (NTIS)

To retrieve temperature and humidity profiles from SSM/T and AMSU, it is important to quantify the contribution of the Earth surface emission. So far, no global estimates of the land surface emissivities are available at SSM/T and AMSU frequencies and sca...

C. Prigent J. P. Wigneron W. B. Rossow J. R. Pardo-Carrion

1999-01-01

196

Partial microwave-assisted wet digestion of animal tissue using a baby-bottle sterilizer for analyte determination by inductively coupled plasma optical emission spectrometry  

NASA Astrophysics Data System (ADS)

A procedure for partial digestion of bovine tissue is proposed using polytetrafluoroethylene (PTFE) micro-vessels inside a baby-bottle sterilizer under microwave radiation for multi-element determination by inductively coupled plasma optical emission spectrometry (ICP OES). Samples were directly weighed in laboratory-made polytetrafluoroethylene vessels. Nitric acid and hydrogen peroxide were added to the uncovered vessels, which were positioned inside the baby-bottle sterilizer, containing 500 mL of water. The hydrogen peroxide volume was fixed at 100 µL. The system was placed in a domestic microwave oven and partial digestion was carried out for the determination of Ca, Cu, Fe, Mg, Mn and Zn by inductively coupled plasma optical emission spectrometry. The single-vessel approach was used in the entire procedure, to minimize contamination in trace analysis. Better recoveries and lower residual carbon content (RCC) levels were obtained under the conditions established through a 2 4-1 fractional factorial design: 650 W microwave power, 7 min digestion time, 50 µL nitric acid and 50 mg sample mass. The digestion efficiency was ascertained according to the residual carbon content determined by inductively coupled plasma optical emission spectrometry. The accuracy of the proposed procedure was checked against two certified reference materials.

Matos, Wladiana O.; Menezes, Eveline A.; Gonzalez, Mário H.; Costa, Letícia M.; Trevizan, Lilian C.; Nogueira, Ana Rita A.

2009-06-01

197

Microwave land emissivity and skin temperature for AMSU-A and B assimilation over land  

Microsoft Academic Search

SUMMARY AMSU-A and -B measurements are stillnot extensively used over land surfaces for atmospheric applications. Recent studies have shown that it should now be possible to take advantage of the information content of these instruments provided land emissivity and skin temperature estimates are improved. This paper reports on comparisons between three land-surface schemes using the Meteo-France four-dimensional variational (4D-Var) assimilation

Fatima Karbou; Élisabeth Gérard; Florence Rabier

2006-01-01

198

Monitor the microwave thermal emission anomaly around the Yushu earthquake fault zone by using AMSR-E data  

NASA Astrophysics Data System (ADS)

Earthquake is caused by collision and compression of lithosphere plates. It has been found that during rock failure under lithosphere plate compression, some anomalies of thermal emission at certain frequencies, e.g. 300MHz, 2GHz and 22GHz, might be observed. Satellite-borne AMSR-E (Advanced Microwave Scanning Radiometer-EOS) has dual-polarized 12 channels (6.925, 10.65, 18.7, 23.8, 36.5 and 89GHz), where two channels, 18.7 and 23.8GHz, are close to the sensitive frequency, i.e. 22GHz. In this paper, the brightness temperature (Tb) at the channel 18.7GHz is especially analyzed to see if the emission anomaly is correlated with the earthquake in Yushu area, Qinghai province (32°N-34°N, 96°E-98°E), China on April 14, 2010. An anomaly index (RAI, radiation anomaly index) is defined for monitoring the Tb change and RAI during prior- and post-earthquake, and another channels, i.e. 23.8 and 10.6 GHz, as the assistance to exclude the influences most likely from atmospheric water vapor and terrain surface temperature on RAI. The AMSR-E Tb data during 2003-2010 were collected, and RAI of Yushu area indicated plausible anomaly on April 12, 2010, which is the date that two days before the Yushu earthquake. Thus, the analysis of RAI might provide a feasible tool for earthquake forecast from multi-year observations of AMSR-E data.

Chen, Hao; Jin, Yaqiu

2010-09-01

199

Characterization of low-pressure microwave and radio frequency discharges in oxygen applying optical emission spectroscopy and multipole resonance probe  

NASA Astrophysics Data System (ADS)

Optical emission spectroscopy (OES) and multipole resonance probe (MRP) are adopted to characterize low-pressure microwave (MW) and radio frequency (RF) discharges in oxygen. In this context, both discharges are usually applied for the deposition of permeation barrier SiOx films on plastic foils or the inner surface of plastic bottles. For technological reasons the MW excitation is modulated and a continuous wave (cw) RF bias is used. The RF voltage produces a stationary low-density plasma, whereas the high-density MW discharge is pulsed. For the optimization of deposition process and the quality of the deposited barrier films, plasma conditions are characterized using OES and MRP. To simplify the comparison of applied diagnostics, both MW and RF discharges are studied separately in cw mode. The OES and MRP diagnostic methods complement each other and provide reliable information about electron density and electron temperature. In the MW case, electron density amounts to ne = (1.25 ± 0.26) × 1017 m?3, and kTe to 1.93 ± 0.20 eV, in the RF case ne = (6.8 ± 1.8)×1015 m?3 and kTe = 2.6 ± 0.35 eV. The corresponding gas temperatures are 760±40 K and 440±20 K.

Steves, Simon; Styrnoll, Tim; Mitschker, Felix; Bienholz, Stefan; Nikita, Bibinov; Awakowicz, Peter

2013-11-01

200

Coupling of the snow thermodynamic model SNOWPACK with the Microwave Emission Model for Layered Snowpacks (MEMLS) for Snow Water Equivalent (SWE) retrievals  

NASA Astrophysics Data System (ADS)

Seasonal snow cover plays an important role in the surface energy balance through its high albedo and low thermal conductivity and. As a response to the recent evidence of warming temperatures, a reduction in snow spatial cover and thickness across the Northern Hemisphere has been observed over the last few decades. Although numerous studies have looked at snow properties retrievals from space (i.e. snow water equivalent, SWE), uncertainties remain with regards to the various contributions to the microwave signal such as vegetation and lake fractions as well as topography and atmospheric effects. In order to retrieve snow information from space, the observation scale has to be reduced to understand the various contributions to the signal, and data assimilation using emission models coupled with snow thermodynamic models do present an interesting avenue. Passivre microwave emission is strongly sensitive to snow grain size, and a proper assessment of this variable is required. This work presents an innovative approach to measure and better define snow grains through accurate measurements of specific surface area (SSA) using infrared photography at 1300 nm and laser measurements at 1310 nm. The relationship between infrared reflectance and snow grain morphology parameters measured from directional lighting photographs is also investigated. Using the theoretical snow albedo model of Kokhanovsky and Zege (2004), vertical SSA profiles are derived and coupled to snow thermodynamic and microwave emission models (SNOWPACK and MEMLS). Results show that with proper assessment of snow grains, simulations of brightness temperatures are improved when compared to field measurements from airborne passive microwave radiometers. With accurate brightness temperatures simulations, SWE retrievals through an assimilation scheme are improved.

Langlois, A.; Royer, A.; Derksen, C.

2011-12-01

201

Impact of Hillslope-Scale Organization of Topography, Soil Moisture, Soil Temperature, and Vegetation on Modeling Surface Microwave Radiation Emission  

Microsoft Academic Search

Microwave radiometry will emerge as an important tool for global remote sensing of near-surface soil moisture in the coming decade. In this modeling study, we find that hillslope-scale topography (tens of meters) influences microwave brightness temperatures in a way that produces bias at coarser scales (kilometers). The physics underlying soil moisture remote sensing suggests that the effects of topography on

Alejandro N. Flores; Valeriy Y. Ivanov; Dara Entekhabi; Rafael L. Bras

2009-01-01

202

In search of water vapor on Jupiter: Laboratory measurements of the microwave properties of water vapor and simulations of Jupiter's microwave emission in support of the Juno Mission  

Microsoft Academic Search

This research has involved the conduct of a series of laboratory measurements of the centimeter-wavelength opacity of water vapor along with the development of a hybrid radiative transfer ray-tracing simulator for the atmosphere of Jupiter which employs a model for water vapor opacity derived from the measurements. For this study an existing Georgia Tech high-sensitivity microwave measurement system (Hanley and

Bryan Mills Karpowicz

2010-01-01

203

Modification and evaluation of a microwave plasma/atomic emission detector system  

NASA Astrophysics Data System (ADS)

Modifications made to an Applied Chromatography Systems plasma emission detector and the evaluation of the performance of the modified instrument were described. The detector modified was the MPD-850. The overall performance of the modified equipment was much improved for carbon (7440440) determination relative to that found for the original instrument. Limits of detection were somewhat higher for the other elements examined in the study including hydrogen (1333740), fluorine (778414), chlorine (7782505), bromine (7726956), and iodine (7553562). The carbon response for seven of the compounds examined in the study did not appear to be compound dependent when the helium flow rate was 70 milliliters/minute. Toluene (108883) and 2-chlorobutane (78864) responses were lower than expected. Carbon responses for two fluorinated compounds were also low, possibly as a result of a fluorine/quartz tube wall interaction. Modification of the original system included replacement of the 1/4 gamma cavity with a Beenakker TM010 cavity, replacement of the gas flow control unit with electronic mass flow controllers, addition of valves and plumbing associated with a solvent venting scheme, and construction of a gas chromatographic/plasma interface.

Birch, M. Eileen

1992-05-01

204

Anomalous conductivity in Hall thrusters: Effects of the non-linear coupling of the electron-cyclotron drift instability with secondary electron emission of the walls  

NASA Astrophysics Data System (ADS)

With the help of an implicit particle-in-cell code, we have shown in a previous paper that the electron-cyclotron drift instability was able to induce anomalous conductivity as well as anomalous heating. As such it can be a major actor among the mechanisms involved in the operation of Hall thrusters. However, experimental results show that the nature of wall material has a significant effect on the behavior of the thruster. The purpose of this paper is to study the plasma-wall interaction in the case where the plasma is heated self-consistently by electrostatic fluctuations induced by the electron-cyclotron drift instability.

Héron, A.; Adam, J. C.

2013-08-01

205

LIRAS mission for lunar exploration by microwave interferometric radiometer: Moon's subsurface characterization, emission model and numerical simulator  

NASA Astrophysics Data System (ADS)

The "Lunar Interferometric Radiometer by Aperture Synthesis" (LIRAS) mission is promoted by the Italian Space Agency and is currently in feasibility phase. LIRAS' satellite will orbit around the Moon at a height of 100 km, with a revisiting time period lower than 1 lunar month and will be equipped with: a synthetic aperture radiometer for subsurface sounding purposes, working at 1 and 3 GHz, and a real aperture radiometer for near-surface probing, working at 12 and 24 GHz. The L-band payload, representing a novel concept for lunar exploration, is designed as a Y-shaped thinned array with three arms less than 2.5 m long. The main LIRAS objectives are high-resolution mapping and vertical sounding of the Moon subsurface by applying the advantages of the antenna aperture synthesis technique to a multi-frequency microwave passive payload. The mission is specifically designed to achieve spatial resolutions less than 10 km at surface and to retrieve thermo-morphological properties of the Moon subsurface within 5 m of depth. Among LIRAS products are: lunar near-surface brightness temperature, subsurface brightness temperature gross profile, subsurface regolith thickness, density and average thermal conductivity, detection index of possible subsurface discontinuities (e.g. ice presence). The following study involves the preliminary design of the LIRAS payload and the electromagnetic and thermal characterization of the lunar subsoil through the implementation of a simulator for reproducing the LIRAS measurements in response to observations of the Moon surface and subsurface layers. Lunar physical data, collected after the Apollo missions, and LIRAS instrument parameters are taken as input for the abovementioned simulator, called "LIRAS End-to-end Performance Simulator" (LEPS) and obtained by adapting the SMOS End-to-end Performance Simulator to the different instrumental, orbital, and geophysical LIRAS characteristics. LEPS completely simulates the behavior of the satellite when it becomes operational providing the extrapolation of lunar brightness temperature maps in both Antenna frame (the cosine domain) and on the Moon surface and allowing an accurate analysis of the instrument performance. The Moon stratigraphy is reproduced in LEPS environment through three scenarios: a macro-layer of regolith; two subsequent macro-layers of regolith and rock; three subsequent macro-layers of regolith, ice and rock, respectively. These scenarios are studied using an incoherent approach, taking into account the interaction between the upwelling and downwelling radiation contributions from each layer to model the resulting brightness temperature at the surface level. It has been considered that the radiative behavior of the Moon varies over time, depending on solar illumination conditions, and it is also function of the material properties, layer thickness and specific position on the lunar crust; moreover it has been examined its variation with frequency, observation angle, and polarization. Using the proposed emission model it has been possible to derive a digital thermal model in the microwave frequency of the Moon, allowing in-depth analysis of the lunar soil consistency; this collected information could be related with a lunar digital elevation model in order to achieve global coverage information on topological aspects. The main results of the study will be presented at the conference.

Pompili, Sara; Silvio Marzano, Frank; Di Carlofelice, Alessandro; Montopoli, Mario; Talone, Marco; Crapolicchio, Raffaele; L'Abbate, Michelangelo; Varchetta, Silvio; Tognolatti, Piero

2013-04-01

206

Optical emission spectroscopy study of a medium pressure Nitrogen flowing afterglow from a ˜1kW microwave excited plasma source  

NASA Astrophysics Data System (ADS)

Nitrogen flowing afterglows in the medium pressure range (1-10torr) are of topical interest for applications in semiconductor film growth and biological decontamination. The spatio-temporal decay characteristics of a 2.54GHz microwave excited flowing N2 plasma have been investigated, after a T-junction was introduced in the plasma path to optically isolate the plasma source and afterglow. The results from optical emission spectroscopy studies (?=200-1000nm), including gas temperature estimates deduced from high resolution spectra, are compared with a simple kinetic model for key atomic and molecular nitrogen species, and are correlated to gas pressure, and gas flow rates.

Carman, Robert; Ha, Peter; Boswell, Rod; Corr, Cormac

2011-11-01

207

A contribution to the analysis of microamounts of biological samples using a combination of graphite furnace and microwave induced plasma atomic emission spectroscopy  

NASA Astrophysics Data System (ADS)

The use of a commercial graphite furnace combined with a TM 110 microwave cavity for the multielement analysis of small-volume liquid samples by microwave-induced plasma atomic emission spectroscopy is described. Sample aliquots of 5-50 ?l are dried at 100°C and subsequently vaporized by heating up to 2400°C. When the dry vapour cloud is evoluted into a 40 W argon microwave plasma with an argon carrier gas flow of 4.51/min, detection limits for Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Tl and Zn range from 1-50 ng/ml. Atomic lines are predominant. In routine analysis the analytical performance of the system is judged by the analysis times of 2-3 min per sample, the absence of memory effects and relative standard deviations in the range of 0.02-6.07. The analytical precision is improved by a factor of 2 by using a reference line. As varying alkaline contents, organics and various anions evoke matrix effects, the analysis of real samples requires the use of standard addition methods. Analysis results for Cd, Cu, Mn, Pb and Zn in NBS orchard leaves and bovine liver agree well with certified values. Direct determinations of Fe, Cu and Zn in 50 ?l serum samples are possible when applying adequate thermal decomposition of samples in the furnace.

Aziz, A.; Broekaert, J. A. C.; Leis, F.

208

An evaluation of the transferability of a coupled snow hydrology and microwave emission model for data-sparse regions  

NASA Astrophysics Data System (ADS)

A coupled snow hydrology-emission model LSHM-MEMLS [Devonec and Barros 2002, Wiesmann and Mätzler 1999, and Mätzler and Wiesmann 1999] was tested independently for two very different climatic and physiographic regions (Valdai and CLPX2002-2003) for both wet and dry snow regimes over multiple years with good results both in terms of capturing the evolution of snowpack physical properties, and the radiometric signature consistent with SMMR, SSM/I and AMSR-E observations at 18-19, 22-23, and 36-37 GHz V and H polarizations. These applications demonstrate transferability of the modeling system, and its potential utility in large-scale retrieval over large areas with limited if any ground-based observations to constrain the model or for data-assimilation. Despite overall good skill as demonstrated by relatively low errors, one weakness was identified with respect to the simulation of the radiative behavior of the snowpack, especially for horizontal polarization, when ice layers (ice lenses) form due to freezing of liquid water either due to daytime melting, or due to rain-on-snow events. Furthermore, it was established that a more accurate estimation of snow density especially in the case of wet snow regimes would be important to improve skill for vertical polarization. These weaknesses were attributed to the single-layer formulation of the LSHM. Consequently, a multi-layer snow hydrology model (MLSHM) that can capture the events and snowpack gradients in water content and structure through accumulation, ripening and melting phases was developed and coupled to MEMLS. Significant differences between the simulations using the single and multilayer model formulations were found in the ripening and melting phases when wet snow regimes are more frequent. These differences result from differences in snow density, with the single-layer formulation exhibiting higher density (shallower snow depths) and faster melting rates. Whereas there are no significant changes in the microwave brightness temperatures in the vertical polarization from single to multilayer simulations, there is dramatic improvement in the results for horizontal polarization. Overall error statistics and detailed analysis of physical behavior show that the coupled MLSHM-MEMLS is apt to be used in data-assimilation in snow retrieval.

Kang, D.; Barros, A. P.

2010-12-01

209

Anomalous zones (domal)  

SciTech Connect

Each zone contains several anomalous salt properties (anomalous features). Zones cannot be characterized by any single property Zones are highly variable, lenticular, and discontinuous in detail; however, once established, they commonly have a predictable trend. The individual anomalous features can occur alone (locally in pairs) over areas of various sizes and shapes. These alone occurrences are not anomalous zones. Anomalous zones may be of any origin, and origin is not part of the definition. Typical origins include: primary (sedimentary), external sheath zone, separating two spines of salt, or caused by toroidal flow. The major importance of an anomalous zone is that it consists of various anomalous features distributed discontinuously along the zone. Thus, if three or more anomalous properties are observed together, one should look for others. The anomalous zones observed in the Gulf Coast thus far are vertical, linear, and semicontinuous. Most are reasonably straight, but some bend sharply, end abruptly, or coalesce. Textures in salt involve grain size, color (white to dark gray), grain shape, or grain distribution of the salt. Typical anomalous textures are coarse-grain, poikiloblastic, and friability. A change in color is commonplace and seldom anomalous. Structural anomalous features, broadly defined, account for most of the rest of the anomalous features. Not uncommonly they cause mining problems. Among the structural anomalous features: INCLUSIONS: Sediments, hydrocarbons, brine, gases. Common gases are air (as N{sub 2}), CH-compounds, CO{sub 2}, and H{sub 2}S. STRUCTURES: Sheared salt, undue stabbing or jointing, voids (crystal-lined pockets), permeability, increased porosity COMPOSITION: High anhydrite content, visible anhydrite as grains or boudins, very black salt = disseminated impurities such as clay.

Kupfer, D.H. (Louisiana State Univ., Baton Rouge (USA))

1990-09-01

210

On-line microwave-based preconcentration device for inductively coupled plasma atomic emission spectrometry: application to the elemental analysis of spirit samples.  

PubMed

A microwave-based thermal nebulizer (MWTN) has been employed for the first time as on-line preconcentration device in inductively coupled plasma atomic emission spectrometry (ICP-AES). By the appropriate selection of the experimental conditions, the MWTN could be either operated as a conventional thermal nebulizer or as on-line analyte preconcentration and nebulization device. Thus, when operating at microwave power values above 100 W and highly concentrated alcohol solutions, the amount of energy per solvent mass liquid unit (EMR) is high enough to completely evaporate the solvent inside the system and, as a consequence, the analyte is deposited (and then preconcentrated) on the inner walls of the MWTN capillary. When reducing the EMR to the appropriate value (e.g., by reducing the microwave power at a constant sample uptake rate) the retained analyte is swept along by the liquid-gas stream and an analyte-enriched aerosol is generated and next introduced into the plasma cell. Emission signals obtained with the MWTN operating in preconcentration-nebulization mode improved when increasing preconcentration time and sample uptake rate as well as when decreasing the nozzle inner diameter. When running with pure ethanol solution at its optimum experimental conditions, the MWTN in preconcentration-nebulization mode afforded limits of detection up to one order of magnitude lowers than those obtained operating the MWTN exclusively as a nebulizer. To validate the method, the multi-element analysis (i.e. Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Pb and Zn) of different commercial spirit samples in ICP-AES has been performed. Analyte recoveries for all the elements studied ranged between 93% and 107% and the dynamic linear range covered up to 4 orders of magnitude (i.e. from 0.1 to 1000?gL(-1)). In these analysis, both MWTN operating modes afforded similar results. Nevertheless, the preconcentration-nebulization mode permits to determine a higher number of analytes due to its higher detection capabilities. PMID:23598185

Grindlay, Guillermo; Gras, Luis; Hernandis, Vicente; Mora, Juan

2013-01-03

211

Observation of extreme ultraviolet hydrogen emission from incandescently heated hydrogen gas with strontium that produced an anomalous optically measured power balance  

Microsoft Academic Search

We report the observation of intense extreme ultraviolet (EUV) emission from incandescently heated atomic hydrogen and atomized strontium. It has been reported that intense EUV emission was observed at low temperatures (e.g. ?103K) from atomic hydrogen and certain atomized elements or certain gaseous ions which ionize at integer multiples of the potential energy of atomic hydrogen, 27.2eV[1–5]. Strontium ionizes at

Randell L. Mills; Mark Nansteel; Ying Lu

2001-01-01

212

Chandra ACIS-S imaging spectroscopy of anomalously faint X-ray emission from Comet 103P/Hartley 2 during the EPOXI encounter  

NASA Astrophysics Data System (ADS)

We present results from the Chandra X-ray Observatory's characterization of the X-ray emission from Comet 103P/Hartley 2, in support of NASA's Deep Impact Extended close flyby of the comet on 04 November 2010. The comet was observed 4 times for a total on target time of ˜60 ks between the 17th of October and 16th of November 2010, with two of the visits occurring during the EPOXI close approach on 04 November and 05 November 2010. X-ray emission from 103P was qualitatively similar to that observed for collisionally thin Comets 2P/Encke (Lisse, C.M. et al. [2005]. Astrophys. J. 635, 1329-1347) and 9P/Tempel 1 (Lisse, C.M. et al. [2007]. Icarus 190, 391-405). Emission morphology offset sunward but asymmetrical from the nucleus and emission lines produced by charge exchange between highly stripped C, N, and O solar wind minor ions and coma neutral gas species were found. The comet was very under-luminous in the X-ray at all times, representing the 3rd faintest comet ever detected (LX = 1.1 ± 0.3 × 1014 erg s-1). The coma was collisionally thin to the solar wind at all times, allowing solar wind ions to flow into the inner coma and interact with the densest neutral coma gas. Localization of the X-ray emission in the regions of the major rotating gas jets was observed, consistent with the major source of cometary neutral gas species being icy coma dust particles. Variable spectral features due to changing solar wind flux densities and charge states were also seen. Modeling of the Chandra observations from the first three visits using observed gas production rates and ACE solar wind ion fluxes with a charge exchange mechanism for the emission is consistent with the temporal and spectral behavior expected for a slow, hot wind typical of low latitude emission from the solar corona interacting with the comet's neutral coma. The X-ray emission during the 4th visit on 16 November 2010 is similar to the unusual behavior seen for Comet 17P/Holmes in 2007 (Christian, D.J. et al. [2010]. Astrophys. J. Suppl. 187, 447-459) as the solar wind became dominated by a less ionized and faster plasma, more typical of outflow from polar coronal hole regions. We postulate that the overall faintness of the comet seen during all visits is due to the unusually well mixed dust and gas content of this hyperactive comet's coma producing Auger electrons rather than X-rays via charge exchange with the solar wind. An alternative possible explanation for the faintness of the comet's X-ray emission, and its unusual high CV and unusually low CVI emission, is that the impinging solar wind was drastically slowed in the inner coma, below 150 km s-1, before charge exchanging with cometary neutrals.

Lisse, C. M.; Christian, D. J.; Wolk, S. J.; Dennerl, K.; Bodewits, D.; Combi, M. R.; Lepri, S. T.; Zurbuchen, T. H.; Li, J. Y.; Dello-Russo, N.; Belton, M. J. S.; Knight, M. M.

2013-02-01

213

Cryogenic Microwave Cavity for Semiconductor Diagnostics  

Microsoft Academic Search

A replaceable wall microwave cavity for semiconductor diagnostics is described for operation at cryogenic temperatures. A method of temperature compensation of resonant frequency is developed to minimize the frequency deviation due to thermal contraction of the cavity body. The anomalous skin effect at low temperatures is observed and taken into consideration.

Morris E. Brodwin; Pao-Sun Lu

1969-01-01

214

Anomalous diffraction approximation limits  

NASA Astrophysics Data System (ADS)

It has been reported in a recent article [Liu, C., Jonas, P.R., Saunders, C.P.R., 1996. Accuracy of the anomalous diffraction approximation to light scattering by column-like ice crystals. Atmos. Res., 41, pp. 63-69] that the anomalous diffraction approximation (ADA) accuracy does not depend on particle refractive index, but instead is dependent on the particle size parameter. Since this is at odds with previous research, we thought these results warranted further discussion.

Videen, Gorden; Chýlek, Petr

215

Review of unprecedented ULF electromagnetic anomalous emissions possibly related to the Wenchuan MS = 8.0 earthquake, on 12 May 2008  

NASA Astrophysics Data System (ADS)

This work presents ground based ultra low frequency (ULF) electromagnetic field measurements in the frequency range 0.1-10 Hz from January 2007 to December 2008. In this time period a strong earthquake series hits the Wenchuan region with a main shock of magnitude MS = 8.0 on 12 May 2008. The Hebei ULF electromagnetic observation network includes eight observation stations in north China and the observation system named E-EM is employed to record the electric potential difference between two electrodes with an analog automatic real-time continuous pen recorder. First, weak electric signals appeared on 11 October 2007 at Ningjin station, most of which are with relative long periods ~0.4-3 s and unequal amplitudes ~0.5-20 mm. Then, similar signals appeared at Gaobeidian station at the end of October. Abnormal behavior with various time intervals appeared randomly and not every day. At the beginning of April 2008, one and a half months before the Wenchuan MS = 8.0 earthquake, the anomalies were gradually subject to an intensive increase mainly in Gaobeidian SN direction and Ningjin EW direction. The abnormal behavior appeared almost every day and the amplitudes of electric signals, with short periods of ~0.1-0.3 s, enhanced to ~3-30 mm. Qingxian station started to record marginally high frequency signals in SN and EW components in the middle of April. On 9 May, 3 days before the main shock, the amplitude of high frequency information increased sharply at the same time in two components at Gaobeidian station and the maximum amplitude was up to 70 mm, i.e. 1.3 mV m-1 for the electric field. This situation did not stop until 17 May, 5 days after the main event. However, this kind of climax phenomena did not happen at Ningjin station and Qingxian station. Then weak anomalous information lasted about four months again, and strong signals appeared again for a short time before several powerful aftershocks. It is the first time that an abnormity with so large an amplitude and so long a duration time in the observation history of this network though several strong earthquakes were recorded. Furthermore, no obvious interferences have been found during this period. So this event is possibly related to this shock although all these three stations are more than 1300 km away from the Wenchuan earthquake epicenter.

Li, M.; Lu, J.; Parrot, M.; Tan, H.; Chang, Y.; Zhang, X.; Wang, Y.

2013-02-01

216

Formation of Electron Distribution Function in ECR Discharge Sustained by Strong Microwave Emission in an Open Trap  

SciTech Connect

We consider a formation of Electron Distribution Function (EDF) in the Electron Cyclotron Resonance (ECR) discharge in an open trap. The ECR heating by strong microwaves, ionization, collisions and ambipolar losses are considered. The model is based on a system of two-dimensional Fokker-Plank equation for EDF. The stationary solution for EDF is investigated analytically. It consists of three groups of electrons: hot electrons with highly anisotropic velocity distribution that are heated in the ECR region, cold electrons with isotropic distribution that define the losses from the trap and warm electrons with considerably anisotropic distribution that are concentrated in the center of the trap and do not reach the ECR region. We build a qualitative model for the electron distribution function such that the original differential equation for EDF is transformed into two algebraic equations with two unknown parameters: neutral density and main plasma density. The latter can be solved analytically. The applicability of these results to a self-consistent model for ECR ion source is discussed. We show that the solution contradicts experimental results so that important effect is not taken into account in the model.

Erukhimov, V.L.; Semenov, V.E. [Institute of Applied Physics, RAS, Russia, 603950, Nizhny Novgorod, Ulyanova 46 (Russian Federation)

2005-03-15

217

Foundations for statistical-physical precipitation retrieval from passive microwave satellite measurements. Part II: Emission-source and generalized weighting-function properties of a time-dependent cloud-radiation model  

Microsoft Academic Search

The authors present the second part of a study on the development of a framework for precipitation retrieval from space-based passive microwave measurements using a three-dimensional time-dependent cloud model to establish the microphysical setting. The first developed the theory needed to interpret the vertically distributed radiative sources and the emission-absorption-scattering processes responsible for the behavior of frequency-dependent top-of-atomsphere brightness temperatures

Alberto Mugnai; Eric A. Smith; Gregory J. Tripoli

1993-01-01

218

Anomalous Soil Temperature and CO2 Emissions at Cerro Pacho (Coatepeque Caldera) and Santa Ana Volcano before the October 1, 2005 Eruption of Santa Ana Volcano  

NASA Astrophysics Data System (ADS)

Coatepeque Caldera and Santa Ana Volcano belong to the Santa Ana-Izalco-Coatepeque volcanic complex in western El Salvador. The last eruption of Santa Ana Volcano on October 1, 2005 killed two people and damaged 65% of the cultivated land around the volcano due to ash emissions and gases. Prior and after the eruption, we carry out several CO2 soil efflux and soil temperature surveys of Cerro Pacho fumarolic field and Santa Ana Volcano crater. For the diffuse CO2 emission, at Cerro Pacho the total CO2 efflux emited to the atmosphere from an area of 2600 m2 on April 1, September 7, and October 26, 2005, was 77, 99 and 64 kg/day respectively. In comparison, at the south-east perimeter of Santa Ana Crater, CO2 emissions on September 2 and September 21, 2005, were 112 and 442 g/m2 day, respectively (Barahona et al.,2007,this meeting). These values are one order of magnitude higher than the 15 g/m2 day measured in the same region by Salazar et al. (2004). For the soil temperatures at Cerro Pacho and at the south of Santa Ana crater, three areas of temperatures higher than 60°C were identified. According to Allis (1979), for soil temperatures lower than 60°C the dominant heat transport mechanism is conductive, there is a transition zone between 60-70°C, and the convective zone occurs at temperatures higher than 70°C up to the boiling point. At Santa Ana crater and at Cerro Pacho, the temperature anomalies were oriented in the NW-SE and E-W direction. In Santa Ana crater, the conductive zone was more important with a 49.1% of the surveyed area on May 8, and a 57% on April 7, 2005. This increase in convective heat flow suggest an increase in thermal heat from the volcano. At Cerro Pacho we have only a slight difference of 90 to 92% in the conductive area during April 3 and October 26, 2005, respectively. The increase in diffuse soil CO2 and the variations in the thermal field at the Santa Ana Crater and the Cerro Pacho fumarolic field can be interpreted as premonitory signals of the Santa Ana Volcano eruption. At other active volcanoes, monitoring of the soil temperature and diffuse emissions of gases could be important methods to follow the state of activity of a volcano.

Olmos, R.; Barahona, F.; Benítez, J.; Henríquez, B.; Hernández, A.; Funes, R.; López, D.; Hernández, P.; Pérez, N.

2007-05-01

219

Measurement of anomalously strong emission from the 1s-9p transition in the spectrum of H-like phosphorus following charge exchange with molecular hydrogen.  

PubMed

We have measured K-shell x-ray spectra of highly ionized argon and phosphorus following charge exchange with molecular hydrogen at low collision energy in an electron beam ion trap using an x-ray calorimeter array with ?6??eV resolution. We find that the emission at the high end of the Lyman series is greater by a factor of 2 for phosphorus than for argon, even though the measurement was performed concurrently and the atomic numbers are similar. This does not agree with current theoretical models and deviates from the trend observed in previous measurements. PMID:20867978

Leutenegger, M A; Beiersdorfer, P; Brown, G V; Kelley, R L; Kilbourne, C A; Porter, F S

2010-08-05

220

Measurement of Anomalously Strong Emission from the 1s-9p Transition in the Spectrum of H-Like Phosphorus Following Charge Exchange with Molecular Hydrogen  

SciTech Connect

We have measured K-shell x-ray spectra of highly ionized argon and phosphorus following charge exchange with molecular hydrogen at low collision energy in an electron beam ion trap using an x-ray calorimeter array with {approx}6 eV resolution. We find that the emission at the high end of the Lyman series is greater by a factor of 2 for phosphorus than for argon, even though the measurement was performed concurrently and the atomic numbers are similar. This does not agree with current theoretical models and deviates from the trend observed in previous measurements.

Leutenegger, M. A.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S. [NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States); Beiersdorfer, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Space Sciences Laboratory, University of California, Berkeley, California 96720 (United States); Brown, G. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2010-08-06

221

Magnetic Nanoparticles in the Interstellar Medium: Emission Spectrum and Polarization  

NASA Astrophysics Data System (ADS)

The presence of ferromagnetic or ferrimagnetic nanoparticles in the interstellar medium would give rise to magnetic dipole radiation at microwave and submillimeter frequencies. Such grains may account for the strong millimeter-wavelength emission observed from a number of low-metallicity galaxies, including the Small Magellanic Cloud. We calculate the absorption and scattering cross sections for such grains, with particular attention to metallic Fe, magnetite Fe3O4, and maghemite ?-Fe2O3, all potentially present in the interstellar medium. The rate of Davis-Greenstein alignment by magnetic dissipation is also estimated. We determine the temperature of free-flying magnetic grains heated by starlight and calculate the polarization of the magnetic dipole emission from both free-fliers and inclusions. For inclusions, the magnetic dipole emission is expected to be polarized orthogonally relative to the normal electric dipole radiation. Magnetic dipole radiation will contribute significantly to the 20-40 GHz anomalous microwave emission only if a large fraction of the Fe is in metallic Fe iron nanoparticles with extreme elongations. Finally, we present self-consistent dielectric functions for metallic Fe, magnetite Fe3O4, and maghemite ?-Fe2O3, enabling calculation of absorption and scattering cross sections from microwave to X-ray wavelengths.

Draine, B. T.; Hensley, Brandon

2013-03-01

222

Anomalous electronic structure of ionic liquids determined by soft x-ray emission spectroscopy: contributions from the cations and anions to the occupied electronic structure.  

PubMed

Soft x-ray emission spectroscopy was used for elucidating the electronic structure of ionic liquids [C(4)mim](+)PF(6)(-) and [C(4)mim](+)OTf(-), where [C(4)mim](+) stands for methylbutylimidazolium cation and OTf(-) for the trifluoromethanesulfonate anion. Nonresonant spectra measured above N, O, and F 1s edges selectively probed the molecular orbitals (MOs) of the cation and anions. They give a clear evidence that the highest occupied molecular orbital of the [C(4)mim](+) cation contributes to the topmost occupied states of the ionic liquids [C(4)mim](+)PF(6)(-), while both cationic and anionic MOs contribute for the case of [C(4)mim](+)OTf(-). Resonant soft x-ray emission spectra at the N 1s edge of these ionic liquids revealed that the energy gap of [C(4)mim](+)PF(6)(-) is solely determined by the [C(4)mim](+) cation, in contrast to usual ionic crystals. The ionic liquids form a new class of the ionic materials from the viewpoint of the electronic structure. PMID:19071928

Kanai, K; Nishi, T; Iwahashi, T; Ouchi, Y; Seki, K; Harada, Y; Shin, S

2008-12-14

223

Observation of the Askaryan Effect: Coherent Microwave Cherenkov Emission from Charge Asymmetry in High-Energy Particle Cascades  

NASA Astrophysics Data System (ADS)

We present the first direct experimental evidence for the charge excess in high-energy particle showers and corresponding radio emission predicted nearly 40 years ago by Askaryan. We directed picosecond pulses of GeV bremsstrahlung photons at the SLAC Final Focus Test Beam into a 3.5 ton silica sand target, producing electromagnetic showers several meters long. A series of antennas spanning 0.3 to 6 GHz detected strong, subnanosecond radio-frequency pulses produced by the showers. Measurements of the polarization, coherence, timing, field strength vs shower depth, and field strength vs frequency are completely consistent with predictions. These measurements thus provide strong support for experiments designed to detect high-energy cosmic rays such as neutrinos via coherent radio emission from their cascades.

Saltzberg, David; Gorham, Peter; Walz, Dieter; Field, Clive; Iverson, Richard; Odian, Allen; Resch, George; Schoessow, Paul; Williams, Dawn

2001-03-01

224

The effects of layers in dry snow on its passive microwave emissions using dense media radiative transfer theory based on the quasicrystalline approximation (QCA/DMRT)  

USGS Publications Warehouse

A model for the microwave emissions of multilayer dry snowpacks, based on dense media radiative transfer (DMRT) theory with the quasicrystalline approximation (QCA), provides more accurate results when compared to emissions determined by a homogeneous snowpack and other scattering models. The DMRT model accounts for adhesive aggregate effects, which leads to dense media Mie scattering by using a sticky particle model. With the multilayer model, we examined both the frequency and polarization dependence of brightness temperatures (Tb's) from representative snowpacks and compared them to results from a single-layer model and found that the multilayer model predicts higher polarization differences, twice as much, and weaker frequency dependence. We also studied the temporal evolution of Tb from multilayer snowpacks. The difference between Tb's at 18.7 and 36.5 GHz can be S K lower than the single-layer model prediction in this paper. By using the snowpack observations from the Cold Land Processes Field Experiment as input for both multi- and single-layer models, it shows that the multilayer Tb's are in better agreement with the data than the single-layer model. With one set of physical parameters, the multilayer QCA/DMRT model matched all four channels of Tb observations simultaneously, whereas the single-layer model could only reproduce vertically polarized Tb's. Also, the polarization difference and frequency dependence were accurately matched by the multilayer model using the same set of physical parameters. Hence, algorithms for the retrieval of snowpack depth or water equivalent should be based on multilayer scattering models to achieve greater accuracy. ?? 2008 IEEE.

Liang, D.; Xu, X.; Tsang, L.; Andreadis, K. M.; Josberger, E. G.

2008-01-01

225

Characterization of a low-pressure chlorine plasma column sustained by propagating surface waves using phase-sensitive microwave interferometry and trace-rare-gas optical emission spectroscopy  

SciTech Connect

Phase-sensitive microwave interferometry and trace-rare-gas optical emission spectroscopy were used to measure the line-integrated electron density, n{sub e}, and electron temperature, T{sub e}, in a high-density chlorine plasma sustained in a quartz discharge tube (inner diameter = 6 mm) by an electromagnetic surface wave at 2.45 GHz. For pressures in the 0.1-1 Torr range, n{sub e} decreased nearly linearly along the tube's z-axis down to the critical density for surface wave propagation, where the plasma decayed abruptly. At lower pressures (< 50 mTorr), however, the plasma extended well beyond this critical point, after which n{sub e} decreased quasiexponentially toward the end of the plasma column. The length of this expansion region increased with decreasing pressure, going from {approx}8 cm at 5 mTorr to {approx}1 cm at 50 mTorr. T{sub e} was nearly independent of the axial position in the main plasma region and strongly decreased in the expansion region at lower pressures. The Cl{sub 2} percent dissociation, {tau}{sub D}, obtained from the calibrated Cl{sub 2} (306 nm)-to-Xe (828 nm) emission ratio, displayed behavior similar to that of n{sub e} and T{sub e}. For example, at 5 mTorr, {tau}{sub D} was close to 100% near the wave launcher and {approx}70% at 0.5 cm from the end of the plasma column.

Mattei, S.; Boudreault, O.; Stafford, L. [Departement de Physique, Universite de Montreal, Montreal, Quebec H3C 3J7 (Canada); Khare, R.; Donnelly, V. M. [Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204 (United States)

2011-06-01

226

Determination of methylmercury in fish tissue by gas chromatography with microwave-induced plasma atomic emission spectrometry after derivatization with sodium tetraphenylborate.  

PubMed

The detection of methylmercury species (MeHg) in fish tissue was investigated. Samples were digested with KOH-methanol and acidified prior to extraction with methylene chloride. MeHg was back-extracted from the organic phase into water. An aliquot of this aqueous solution (buffered to pH 5) was subjected to derivatization with sodium tetraphenylborate (NaBPh4) and then extracted with toluene. The organic phase containing MePhHg was injected into a gas chromatograph (GC) which is on-line with a microwave-induced plasma atomic emission spectrometer (MIP-AED). The quantification limit was about 0.6 microg/g and 0.1 microg/g of MeHg (as Hg) for 0.08 g of freeze-dried fish powder and 0.5 g of fresh samples, respectively. Two certified reference materials, CRM 464 (tuna fish) from Community Bureau of Reference-BCR and DORM-2 (dogfish muscle) from National Research Council Canada-NRC were selected for checking the accuracy of the method. This methodology was applied to the determination of MeHg in some kinds of fish from the Carmo river with alluvial gold recovery activities ("garimpos") in Mariana, Minas Gerais, Brazil. PMID:11220340

Palmieri, H E; Leonel, L V

2000-03-01

227

BURST AND PERSISTENT EMISSION PROPERTIES DURING THE RECENT ACTIVE EPISODE OF THE ANOMALOUS X-RAY PULSAR 1E 1841-045  

SciTech Connect

The Swift/Burst Alert Telescope detected the first burst from 1E 1841-045 in 2010 May with intermittent burst activity recorded through at least 2011 July. Here we present Swift and Fermi/Gamma-ray Burst Monitor observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T {sub 90} durations of the bursts range between 18 and 140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8-25) x 10{sup 38} erg, which is on the low side of soft gamma repeater bursts. We find that the bursting activity did not have a significant effect on the persistent flux level of the source. We argue that the mechanism leading to this sporadic burst activity in 1E 1841-045 might not involve large-scale restructuring (either crustal or magnetospheric) as seen in other magnetar sources.

Lin Lin [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Kouveliotou, Chryssa [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Goegues, Ersin; Kaneko, Yuki [Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, Istanbul 34956 (Turkey); Van der Horst, Alexander J. [Universities Space Research Association, NSSTC, Huntsville, AL 35805 (United States); Watts, Anna L.; Wijers, Ralph A. M. J.; Van der Klis, Michiel [Astronomical Institute 'Anton Pannekoek', University of Amsterdam, 1090 GE Amsterdam (Netherlands); Baring, Matthew G. [Department of Physics and Astronomy, Rice University, MS-108, Houston, TX 77251 (United States); Woods, Peter M. [Corvid Technologies, Huntsville, AL 35806 (United States); Barthelmy, Scott; Gehrels, Neil; Mcenery, Julie [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Michael Burgess, James; Chaplin, Vandiver; Goldstein, Adam; Guiriec, Sylvain; Preece, Robert D. [CSPAR, University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Granot, Jonathan [Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Herts AL10 9AB (United Kingdom); Tierney, David, E-mail: lin198361@gmail.com [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

2011-10-10

228

Microwave off-gas treatment apparatus and process  

DOEpatents

The invention discloses a microwave off-gas system in which microwave energy is used to treat gaseous waste. A treatment chamber is used to remediate off-gases from an emission source by passing the off-gases through a susceptor matrix, the matrix being exposed to microwave radiation. The microwave radiation and elevated temperatures within the combustion chamber provide for significant reductions in the qualitative and quantitative emissions of the gas waste stream.

Schulz, Rebecca L. (Aiken, SC); Clark, David E. (Gainesville, FL); Wicks, George G. (North Aiken, SC)

2003-01-01

229

Recent Advancements in Microwave Imaging Plasma Diagnostics  

SciTech Connect

Significant advances in microwave and millimeter wave technology over the past decade have enabled the development of a new generation of imaging diagnostics for current and envisioned magnetic fusion devices. Prominent among these are revolutionary microwave electron cyclotron emission imaging (ECEI), microwave phase imaging interferometers, imaging microwave scattering and microwave imaging reflectometer (MIR) systems for imaging electron temperature and electron density fluctuations (both turbulent and coherent) and profiles (including transport barriers) on toroidal devices such as tokamaks, spherical tori, and stellarators. The diagnostic technology is reviewed, and typical diagnostic systems are analyzed. Representative experimental results obtained with these novel diagnostic systems are also presented.

H. Park; C.C. Chang; B.H. Deng; C.W. Domier; A.J.H. Donni; K. Kawahata; C. Liang; X.P. Liang; H.J. Lu; N.C. Luhmann, Jr.; A. Mase; H. Matsuura; E. Mazzucato; A. Miura; K. Mizuno; T. Munsat; K. and Y. Nagayama; M.J. van de Pol; J. Wang; Z.G. Xia; W-K. Zhang

2002-03-26

230

Streamlined Modeling for Characterizing Spacecraft Anomalous Behavior  

Microsoft Academic Search

Anomalous behavior of on-orbit spacecraft can often be detected using passive, remote sensors which measure electro-optical signatures that vary in time and spectral content. Analysts responsible for assessing spacecraft operational status and detecting detrimental anomalies using non-resolved imaging sensors are often presented with various sensing and identification issues. Modeling and measuring spacecraft self emission and reflected radiant intensity when the

B. Klem; D. Swann

2011-01-01

231

Low temperature anomalous field effect in SrxBa1-xNb2O6 uniaxial relaxor ferroelectric seen via acoustic emission  

NASA Astrophysics Data System (ADS)

Sr0.75Ba0.25Nb2O6 [100]-oriented uniaxial tungsten bronze relaxor crystals have been studied by means of dedicated acoustic emission during their thermal cycling in 150-300 K temperature range under dc electric field (E). A 1st order transition in a modulated incommensurate tetragonal phase has been successfully detected at Tmi = 198 K on heating and Tmi = 184 K on cooling, respectively. As field E enhances, a thermal hysteresis gradually narrows and vanishes in the critical point at Eth = 0.31 kV/cm, above which a phase transition becomes to 2nd order. The Tmi(E) dependence looks as a V-shape dip, not similar that previously has been looked as a smeared minimum between both the two polar and nonpolar tetragonal phases near Tm = 220 ÷ 230 K in the same crystals (Dul'kin et al., J Appl. Phys. 110, 044106 (2011)). Due to such a V-shape dip is characteristic for Pb-based multiaxial perovskite relaxor, a rhombohedral phase is waited to be induced by a field E in the critical point temperature range. The emergence of this rhombohedral phase as a crucial evidence of an orthorhombic phase presumably existing within the modulated incommensurate tetragonal phase in tungsten bronze SrxBa1-xNb2O6 relaxor is discussed.

Dul'kin, E.; Kojima, S.; Roth, M.

2012-04-01

232

Microwave detector  

DOEpatents

A microwave detector (10) is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite (26, 28) produces a magnetization field flux that links a B-dot loop (16, 20). The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means (18, 22) are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

Meldner, Heiner W. (Moss Beach, CA); Cusson, Ronald Y. (Chapel Hill, NC); Johnson, Ray M. (San Ramon, CA)

1986-01-01

233

Anomalous gauge boson interactions  

SciTech Connect

We discuss the direct measurement of the trilinear vector boson couplings in present and future collider experiments. The major goals of such experiments will be the confirmation of the Standard Model (SM) predictions and the search for signals of new physics. We review our current theoretical understanding of anomalous trilinear gauge-boson self interactions. If the energy scale of the new physics is {approximately} 1 TeV, these low energy anomalous couplings are expected to be no larger than {Omicron}(10{sup {minus}2}). Constraints from high precision measurements at LEP and low energy charged and neutral current processes are critically reviewed.

Aihara, H. [Lawrence Berkeley Lab., CA (United States); Barklow, T. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Baur, U. [State Univ. of New York, Buffalo, NY (United States). Dept. of Physics]|[Florida State Univ., Tallahassee, FL (United States). Dept. of Physics] [and others

1995-03-01

234

Microwave Digestion of Crude Oils and Oil Products for the Determination of Trace Metals and Sulphur by Inductively-Coupled Plasma Atomic Emission Spectroscopy.  

National Technical Information Service (NTIS)

A study on the oil microwave digestion for determination of trace metals and sulphur in oil samples by ICP-AES was conducted by examination of the kinetic relationship of microwave digestion processes with different crude oil types, the mechanism of C6 hy...

J. R. Cao

1992-01-01

235

Microwave Playdough  

NSDL National Science Digital Library

This is a recipe for playdough made by mixing household ingredients and cooking it in a microwave. This recipe includes suggestions for artistic embellishments to enhance the sensory experience, like adding glitter or color to the dough. The dough can be used to create simple sculptures, or cast molds of objects. Important: DO NOT add glitter to the mixture before microwaving.

Omsi

2000-01-01

236

Comprehensive interferometric characterization of red and near-infrared emissions of C, H, N, O, F, Cl, Br, I, P, S, and Si in a 370-W microwave-induced helium plasma  

SciTech Connect

The red/near-infrared emission spectrum from a 370-W atmospheric pressure helium microwave-induced plasma (MIP) has been characterized for eleven nonmetals with a Fourier transform spectrometer and silicon photodiode detector. A comprehensive list of all observed lines and relative intensities has been tabulated for MIP-excited emissions of C, H, N, O, F, Cl, Br, I, P, S, Si, and the helium background in the diode detector region 15,750 to 8500 cm/sup -1/ (6349--11,764 A). Many of these red/near-infrared lines (especially of phosphorous and silicon) are reported for the first time in an analytically useful plasma. Data for silicon and phosphorus are shown to fit known Grotrian diagrams. The data of this paper were used with corresponding known upper-state energies and transitions to construct a partial Grotrian diagram for helium plasma emissions of iodine.

Pivonka, D.E.; Schleisman, A.J.J.; Fateley, W.G.; Fry, R.C.

1986-08-01

237

Core temperature measurement by microwave radiometry  

Microsoft Academic Search

A ‘double-container model’ was used for core temperature (Tc) measurement by microwave emission radiometry (MR) of warm fluid inside a tube, placed in a container with a cooler fluid. The intensity of microwaves emitted from the warmer fluid inside the tube were measured using a MR metering device, consisting of an antenna linked to a low-noise radio frequency amplifier (bandwidth

Daniel S. Moran; Uri Eliyahu; Yuval Heled; Shabtai Rabinovitz; Jay Hoffman; Menachem Margaliot

2004-01-01

238

Microwave sterilization.  

PubMed

This study has shown that representative fungi, viruses, and aerobic and anaerobic bacteria, including spore formers, can easily be killed in a conventional microwave oven with proper modifications. Metal instruments, including air turbine handpieces and burs, and acrylic dentures can be sterilized in short periods. Consistent sterilization can be accomplished only if the items to be sterilized are rotated in a three-dimensional manner throughout the microwave cavity. Arcing back to the magnetron and damage to the microwave oven are prevented by placing a radar absorbent material within the oven and with proper insulation of the item to be sterilized. PMID:3884686

Rohrer, M D; Bulard, R A

1985-02-01

239

Anomalous pectoral musculature.  

PubMed

Anomalous disposition of pectoral muscles was encountered in an adult female cadaver on the left side. A prominent cleft separating the sternocostal and clavicular portions of the pectoralis major was noticed. The fibers of pectoralis major were partially fused with the deltoid, resulting in obliteration of the deltopectoral groove. Interestingly, cephalic vein was seen traversing superficial to the clavicular portion of the pectoralis major and pierced it to drain into the axillary vein. The pectoralis minor was inserted mainly on the coracoid process and few fibers were found blending with the coracobrachialis and short head of biceps brachii. Further, pectoralis minimus, a rare anatomic variant, was also observed lying superior to pectoralis minor. It was innervated by a twig from the lateral pectoral nerve at its superficial surface. Awareness of possibility of such anomalous muscles is important for surgeons operating on the chest wall. PMID:19159367

Soni, Simmi; Rath, Gayatri; Suri, Rajesh; Kumar, Hitendra

2008-12-01

240

Anomalous pectoral musculature  

Microsoft Academic Search

Anomalous disposition of pectoral muscles was encountered in an adult female cadaver on the left side. A prominent cleft separating\\u000a the sternocostal and clavicular portions of the pectoralis major was noticed. The fibers of pectoralis major were partially\\u000a fused with the deltoid, resulting in obliteration of the deltopectoral groove. Interestingly, cephalic vein was seen traversing\\u000a superficial to the clavicular portion

Simmi Soni; Gayatri Rath; Rajesh Suri; Hitendra Kumar

2008-01-01

241

Microwave generator  

DOEpatents

A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit there through effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators. 6 figs.

Kwan, T.J.T.; Snell, C.M.

1987-03-31

242

Microwave Ovens  

MedlinePLUS

... Commission (CPSC) Website Laws, Regulations & Standards Manufacturers of electronic radiation emitting products sold in the United States ... and Cosmetic Act (FFDCA), Chapter V, Subchapter C - Electronic Product Radiation Control . Manufacturers of microwave ovens are ...

243

[Experimental study on spectra of compressed air microwave plasma].  

PubMed

Using a microwave plasma generator, compressed air microwave plasma was excited under 1 - 5 atm pressures. Under different pressures and different incident microwave power, the emission spectra of compressed air microwave plasma were studied with a spectra measuring system. The results show that continuum is significant at atmospheric pressure and the characteristic will be weakened as the pressure increases. The band spectra intensity will be reduced with the falling of the incident microwave power and the band spectra were still significant. The experimental results are valuable to studying the characteristics of compressed air microwave plasma and the generating conditions of NO active groups. PMID:23705456

Liu, Yong-Xi; Zhang, Gui-Xin; Wang, Qiang; Hou, Ling-Yun

2013-03-01

244

Microwave tomography  

NASA Astrophysics Data System (ADS)

A technique of microwave and acoustical tomography based on the holographic principle of a constrast material is proposed. This technique is used to obtain an rms-optimal solution for the ultrasonic and microwave visualization of the spatial distribution of the refractive index of an inhomogeneous medium which converges to an exact solution as the number of recorded field samples goes to infinity. Ways to implement the reconstruction algorithm by coherent-optic techniques are examined.

Voskresenskii, D. I.; Voronin, E. N.

245

Microwave annealing  

NASA Astrophysics Data System (ADS)

Microwave annealing of dopants in Si has been reported to produce highly activated junctions at temperatures far below those needed for comparable results using conventional thermal processes. However the details of the kinetics and mechanisms for microwave annealing are far from well understood. Comparisons between MWA and RTA of dopants in implanted Si has been investigated to produce highly activated junctions. First, As, 31P, and BF2 implants in Si substrate were annealed by MWA at temperatures below 550 °C.

Lee, Yao-Jen; Cho, T.-C.; Chuang, S.-S.; Hsueh, F.-K.; Lu, Y.-L.; Sung, P.-J.; Chen, S.-J.; Lo, C.-H.; Lai, C.-H.; Current, Michael I.; Tseng, T.-Y.; Chao, T.-S.; Yang, F.-L.

2012-11-01

246

On a possibility to suppress microwave instability in storage rings using strong longitudinal focusing  

Microsoft Academic Search

Microwave instability has been observed in almost all operational storage rings. It causes anomalous bunch lengthening and energy spread growth. Microwave instability appears to be the main limiting factor in both longitudinal brightness of the electron beam and the achievement of very short bunches [1,2]. The 6D brightness of an electron beam is the main figure of merit for applications

Vladimir N. Litvinenko

1997-01-01

247

Effects of buckyballs and cosmic strings on the cosmic microwave background  

Microsoft Academic Search

This thesis consists of two Cosmic Microwave Background related projects: a simulation of an anomalous foreground component, and a search for a distinct background signature. The Cosmic Microwave Background forms one of the three major pillars of support for the Big Bang theory of the origin of the universe, and is an important source of information about the early universe.

Amy Shiu-Mei Lo

2005-01-01

248

FROM THE CURRENT LITERATURE: Negative-energy waves and the anomalous Doppler effect  

Microsoft Academic Search

A 'profound' physical analogy between two sets of phenomena hitherto studied independently - negative-energy waves (NEW) in dispersive media and the anomalous Doppler effect (ADE) - is probed. The NEW phenomenon is defined (frequency derivative of product of frequency-dependent permittivity times frequency negative) and relations between NEW and dispersion, electron beam (EB), plasma instability, and microwave slow-wave structure phenomena are

M. V. Nezlin

1976-01-01

249

Galactic foreground contributions to the 5-year Wilkinson Microwave Anisotropy Probe maps  

NASA Astrophysics Data System (ADS)

We compute the cross-correlation between intensity and polarization from the 5-year Wilkinson Microwave Anisotropy Probe (WMAP5) data in different sky regions with respect to template maps for synchrotron, dust and free-free emission. We derive the frequency dependence and polarization fraction for all three components in 48 different sky regions of HEALPIX (Nside= 2) pixelization. The anomalous emission associated with dust is clearly detected in intensity over the entire sky at the K (23-GHz) and Ka (33-GHz) WMAP bands, and is found to be the dominant foreground at low Galactic latitudes, between b =-40° and +10°. The synchrotron spectral index obtained from the K and Ka WMAP bands from an all-sky analysis is ?s=-3.32 ± 0.12 for intensity and ?s=-3.01 ± 0.03 for polarized intensity. The polarization fraction of the synchrotron emission is constant in frequency and increases with latitude from ?5 per cent near the Galactic plane up to ?40 per cent in some regions at high latitudes; the average value for |b| < 20° is 8.6 ± 1.7 (stat) ± 0.5 (sys) per cent, while for |b| > 20°, it is 19.3 ± 0.8 (stat) ± 0.5 (sys) per cent. Anomalous dust and free-free emissions appear to be relatively unpolarized. Monte Carlo simulations showed that there were biases of the method due to cross-talk between the components, at up to ?5 per cent in any given pixel, and ?1.5 per cent on average, when the true polarization fraction is low (a few per cent or less). Nevertheless, the average polarization fraction of dust-correlated emission at the K band is 3.2 ± 0.9 (stat) ± 1.5 (sys) per cent or less than 5 per cent at 95 per cent confidence. When comparing real data with simulations, eight regions show a detected polarization above the 99th percentile of the distribution from simulations with no input foreground polarization, six of which are detected at above 2? and display polarization fractions between 2.6 and 7.2 per cent, except for one anomalous region, which has 32 ± 12 per cent. The dust polarization values are consistent with the expectation from spinning dust emission, but polarized dust emission from magnetic-dipole radiation cannot be ruled out. Free-free emission was found to be unpolarized with an upper limit of 3.4 per cent at 95 per cent confidence.

Macellari, N.; Pierpaoli, E.; Dickinson, C.; Vaillancourt, J. E.

2011-12-01

250

Microwave furnace having microwave compatible dilatometer  

DOEpatents

An apparatus for measuring and monitoring a change in the dimension of a sample being heated by microwave energy is described. The apparatus comprises a microwave heating device for heating a sample by microwave energy, a microwave compatible dilatometer for measuring and monitoring a change in the dimension of the sample being heated by microwave energy without leaking microwaves out of the microwave heating device, and a temperature determination device for measuring and monitoring the temperature of the sample being heated by microwave energy. 2 figs.

Kimrey, H.D. Jr.; Janney, M.A.; Ferber, M.K.

1992-03-24

251

Microwave furnace having microwave compatible dilatometer  

DOEpatents

An apparatus for measuring and monitoring a change in the dimension of a sample being heated by microwave energy is described. The apparatus comprises a microwave heating device for heating a sample by microwave energy, a microwave compatible dilatometer for measuring and monitoring a change in the dimension of the sample being heated by microwave energy without leaking microwaves out of the microwave heating device, and a temperature determination device for measuring and monitoring the temperature of the sample being heated by microwave energy.

Kimrey, Jr., Harold D. (Knoxville, TN); Janney, Mark A. (Knoxville, TN); Ferber, Mattison K. (Oak Ridge, TN)

1992-01-01

252

Anomalous splenic artery aneurysm.  

PubMed

Aneurysms of the splenic artery are the most common visceral aneurysm. A splenomesenteric trunk, which involves the splenic artery arising from the superior mesenteric artery (SMA), is rare and occurs in less than 1% of patients. Thus splenic artery aneurysms (SAAs) with an anomalous origin from the SMA are quite rare. We report our experience with the surgical management of a 2.6-cm aneurysm involving a splenic artery arising from the SMA in a 40-year-old woman. This was treated with surgical resection with preservation of the spleen. A discussion about SAAs and the management of aneurysms arising from a splenomesenteric trunk follows. PMID:23526105

Wong, Sydney S N; Lindsay, T F; Roche-Nagle, G

2013-03-22

253

Anomalous splenic artery aneurysm.  

PubMed

Aneurysms of the splenic artery are the most common visceral aneurysm. A splenomesenteric trunk, which involves the splenic artery arising from the superior mesenteric artery (SMA), is rare and occurs in less than 1% of patients. Thus splenic artery aneurysms (SAAs) with an anomalous origin from the SMA are quite rare. We report our experience with the surgical management of a 2.6-cm aneurysm involving a splenic artery arising from the SMA in a 40-year-old woman. This was treated with surgical resection with preservation of the spleen. A discussion about SAAs and the management of aneurysms arising from a splenomesenteric trunk follows. PMID:23526109

Wong, Sydney S N; Lindsay, T F; Roche-Nagle, G

2013-03-22

254

Microwave Generator Experiment at LLNL.  

National Technical Information Service (NTIS)

A high power microwave oscillator known as a Virtual Cathode Oscillator (VIRCATOR) is described here. It is basically a space charge limited field emission cathode injecting electrons through a thin foil into a 4.3 cm radius circular waveguide. The total ...

W. W. Hofer Burkhart S.C R. D. Scarpetti

1983-01-01

255

Improvement of Satellite Data Assimilation with Updated Microwave Land Emissivity Model in CRTM and New Momentum and Thermal Roughness Lengths in GFS  

Microsoft Academic Search

Satellite radiances (infrared and microwave) measure upwelling radiation at the top of atmosphere and being increasingly used for weather and climate prediction systems. Most satellite radiance measurements in various spectral channels are assimilated as radiances through the JCSDA Community Radiative Transfer Model (CRTM) on the NCEP Gridpoint Statistical Interpolation (GSI). It is noticed that the amount of satellite data assimilated

W. Zheng; M. B. Ek; J. Derber; H. Wei; C. J. Meng

2010-01-01

256

Hearing microwaves: the microwave auditory phenomenon  

Microsoft Academic Search

The microwave auditory phenomenon, or the microwave hearing effect, pertains to the hearing of short pulses of modulated microwave radiation at high peak power by humans and laboratory animals. Anecdotal and journalistic reports of the hearing of microwave pulses persisted throughout the 1940s; and 1950s. The first scientific report of the phenomenon appeared in 1961. The effect has been observed

James C. Lin

2001-01-01

257

Proceedings of the URSI Commission II Specialist Meeting on Microwave Scattering and Emission from the Earth Held at Berne (Switzerland) on September 23-26, 1974.  

National Technical Information Service (NTIS)

Contents: Scattering and Emission from water surfaces; Sea-ice, land-ice and snow; Soil, vegetation and geological features; Theoretical studies on scatter and emission; Considerations on systems and techniques.

E. Schanda

1974-01-01

258

Microwave medical devices  

Microsoft Academic Search

This article describes several new microwave medical devices that either were or are being developed at MMTC, Inc. in cooperation with the following institutions: Celsion Corporation, Columbia, Maryland (microwave balloon catheters); Montefiore Medical Center (MMC), Bronx, New York (microwave balloon catheters, dual microwave antennas, and microwave poration); and the University of California at San Francisco (conformal array antennas). The individuals

F. Sterzer

2002-01-01

259

Determination of calcium, copper, iron, magnesium, manganese, potassium, phosphorus, sodium, and zinc in fortified food products by microwave digestion and inductively coupled plasma-optical emission spectrometry: single-laboratory validation and ring trial.  

PubMed

A single-laboratory validation (SLV) and a ring trial (RT) were undertaken to determine nine nutritional elements in food products by inductively coupled plasma-optical emission spectrometry in order to modernize AOAC Official Method 984.27. The improvements involved extension of the scope to all food matrixes (including infant formula), optimized microwave digestion, selected analytical lines, internal standardization, and ion buffering. Simultaneous determination of nine elements (calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, and zinc) was made in food products. Sample digestion was performed through wet digestion of food samples by microwave technology with either closed- or open-vessel systems. Validation was performed to characterize the method for selectivity, sensitivity, linearity, accuracy, precision, recovery, ruggedness, and uncertainty. The robustness and efficiency of this method was proven through a successful RT using experienced independent food industry laboratories. Performance characteristics are reported for 13 certified and in-house reference materials, populating the AOAC triangle food sectors, which fulfilled AOAC criteria and recommendations for accuracy (trueness, recovery, and z-scores) and precision (repeatability and reproducibility RSD, and HorRat values) regarding SLVs and RTs. This multielemental method is cost-efficient, time-saving, accurate, and fit-for-purpose according to ISO 17025 Norm and AOAC acceptability criteria, and is proposed as an extended updated version of AOAC Official Method 984.27 for fortified food products, including infant formula. PMID:22468357

Poitevin, Eric

260

Improvement of AOAC Official Method 984.27 for the determination of nine nutritional elements in food products by Inductively coupled plasma-atomic emission spectroscopy after microwave digestion: single-laboratory validation and ring trial.  

PubMed

A single-laboratory validation (SLV) and a ring trial (RT) were undertaken to determine nine nutritional elements in food products by inductively coupled plasma-atomic emission spectroscopy in order to improve and update AOAC Official Method 984.27. The improvements involved optimized microwave digestion, selected analytical lines, internal standardization, and ion buffering. Simultaneous determination of nine elements (calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, and zinc) was made in food products. Sample digestion was performed through wet digestion of food samples by microwave technology with either closed or open vessel systems. Validation was performed to characterize the method for selectivity, sensitivity, linearity, accuracy, precision, recovery, ruggedness, and uncertainty. The robustness and efficiency of this method was proved through a successful internal RT using experienced food industry laboratories. Performance characteristics are reported for 13 certified and in-house reference materials, populating the AOAC triangle food sectors, which fulfilled AOAC criteria and recommendations for accuracy (trueness, recovery, and z-scores) and precision (repeatability and reproducibility RSD and HorRat values) regarding SLV and RT. This multielemental method is cost-efficient, time-saving, accurate, and fit-for-purpose according to ISO 17025 Norm and AOAC acceptability criteria, and is proposed as an improved version of AOAC Official Method 984.27 for fortified food products, including infant formula. PMID:19916387

Poitevin, Eric; Nicolas, Marine; Graveleau, Laetitia; Richoz, Janique; Andrey, Daniel; Monard, Florence

261

Intense microwave pulses III  

SciTech Connect

The goal of the Intense Microwave Pulses III conference was to present and critically assess new and innovative ideas, together with recent advances, in the generation and transmission of intense microwave pulses. Significant advances were reported on Super-Reltron source development. Also presented were numerous results of research on high-power klystron oscillators and amplifiers. Results of preliminary experimental studies were presented on an L-band Pasotron amplifier. Research was also reported on: vircators; the development of a family of frequency-agile relativistic magnetrons covering the bands from 1 to 3 GHz continuously; the status and challenges of powerful ultrawideband rf sources, including hydrogen spark gap pursers, hydrogen gas switches in combination with high-gain ultrawideband antennas; possible applications of high-power millimeter waves; development of simple, compact, efficient, and robust Hertzian EMP generators using oil spark switches that are capable of producing highly directive impulsive radiation fields with 100-ps rise times at gigawatt power levels; radiative instability theory; high-gain antenna design; antenna-induced parasitic current and backlobe reduction; high-power microwave sources based on photoconductive switching; analysis of ultrawideband pulses; generation of high-power microwave self-similar pulses from a free-electron laser, sheet-electron beam production and transport; theory of helical Cerenkov radiation; cyclotron resonance maser phenomenology; theory and experiments on mode locking in gyrotron oscillators; theory of wideband dielectric Cerenkov maser amplifiers; theory of plasma-filled backward-wave oscillators; high-repetition-rate tunable gyrotrons; field emission array cathodes for millimeter-wave gyrotrons; and high-power gyrotron development for electron cyclotron wave applications in magnetic confinement fusion.

Brandt, H.E. [ed.] [Army Research Lab., Adelphi, MD (United States)

1995-11-01

262

Anomalous two-state model for anomalous diffusion  

NASA Astrophysics Data System (ADS)

An anomalous two-state model (ATSM) with the anomalous long-tailed kinetics of transitions between states is proposed to describe the specific features of anomalous diffusion (AD) and AD-assisted transitions (ADAT) in the double-well potential. In the ATSM the system is assumed to undergo the conventional diffusion in both states but with different diffusion coefficients. The anomalous features of diffusion result from the modulation of the diffusion coefficient caused by transitions between ATSM states. The anomalous space-time evolution predicted by the ATSM is treated within the continuous time random walk theory. With the use of the proposed ATSM the transient behavior of the AD and the ADAT is analyzed in detail. We found a large variety of different (and sometimes peculiar) types of the space-time behavior of the free AD and ADAT. The free AD is found to be of subdiffusion or superdiffusion type for fairly long time depending on the relation between the parameters of the ATSM. The kinetics of the ADAT can be either conventional (exponential) or anomalous (of inverse power type) for different parameters of the model and time.

Shushin, A. I.

2001-11-01

263

On the mechanism of electromagnetic microwave absorption in superfluid helium  

NASA Astrophysics Data System (ADS)

In experiments on electromagnetic (EM) wave absorption in the microwave range in superfluid (SF) helium [1-3], a narrow EM field absorption line with a width on the order of (20-200) kHz was observed against the background of a wide absorption band with a width of 30-40 GHz at frequencies f 0 ? 110-180 GHz corresponding to the roton gap energy ? r ( T) in the temperature range 1.4-2.2 K. Using the so-called flexoelectric mechanism of polarization of helium atoms (4He) in the presence of density gradients in SF helium (HeII), we show that nonresonance microwave absorption in the frequency range 170-200 GHz can be due to the existence of time-varying local density gradients produced by roton excitations in the bulk HeII. The absorption bandwidth is determined by the roton-roton scattering time in an equilibrium Boltzmann gas of rotons, which is t r- r ? 3.4 × 10-11 s at T = 1.4 K and decreases upon heating. We propose that the anomalously narrow microwave resonance absorption line in HeII at the roton frequency f 0( T) = ? r( T)/2? ? appears due to the following two factors: (i) the discrete structure of the spectrum of the surface EM resonator modes in the form of a periodic sequence of narrow peaks and (ii) the presence of a stationary dipole layer in HeII near the resonator surface, which forms due to polarization of 4He atoms under the action of the density gradient associated with the vanishing of the density of the SF component at the solid wall. For this reason, the relaxation of nonequilibrium rotons generated in such a surface dipole layer is strongly suppressed, and the shape and width of the microwave resonance absorption line are determined by the roton density of states, which has a sharp peak at the edge of the roton gap in the case of weak dissipation. The effective dipole moments of rotons in the dipole layer can be directed either along or across the normal to the resonator surface, which explains the experimentally observed symmetric doublet splitting of the resonance absorption line in an external dc electric field perpendicular to the resonator surface. We show that negative absorption (induced emission) of EM field quanta observed after triggering a Kapitza "heat gun" occurs when the occupation numbers for roton states due to "pumping" of rotons exceed the occupation numbers of EM field photons in the resonator.

Pashitskii, E. A.; Pentegov, V. I.

2012-08-01

264

Microwave Sintering of Ceramics.  

National Technical Information Service (NTIS)

Successful adaptation of microwave heating to the densification of ceramic materials require a marriage of microwave and materials technologies. Using an interdisciplinary team of microwave and materials engineers, we have successfully demonstrated the ab...

W. B. Snyder

1989-01-01

265

Total anomalous systemic venous return.  

PubMed

We have described an 18-year-old boy who is asymptomatic nine years after surgical correction of total anomalous systemic venous return. His clinical course and anatomy are compared to the eight previously reported patients. PMID:7355335

Pearl, W R; Spicer, M J

1980-02-01

266

Is Bacteriophage Adsorption Anomalous?  

NASA Astrophysics Data System (ADS)

The study of infection process of bacteria by phages has a long history. One of the paradoxes is that the rate of binding of phage particles to their host is higher than the theoretical limit, k=4paD, assuming that the bacterium is an ideal sink. Here a is the size of the bacterium and D is the diffusion coefficient of the phage. Various explanations were provided in the past to account for the anomalous adsorption, such as bacterial swimming and special roles of appendages on a phage for enhanced binding. Using a common strain E. coli. (YMEL), we investigated phage adsorption and DNA translocation kinetics using a standard tittering technique. We found that phage adsorption depends strongly on the divalent salt (MgSO4) concentration and the adsorption rate can change by orders of magnitude. Even in the strongest adsorption regime, with Mg++=10-2 M, the adsorption coefficient is about 10 times smaller than the theoretical limit, suggesting that the average number of phage receptors on a bacterium is about 50 or so. We also derived a set of rate equations taking into account phage desorption and DNA translocation rates. Surprisingly this set of simple equations explains our experimental data extremely well. Under certain conditions the DNA translocation appears to be "frozen", with a nearly zero translocation rate. Such a condition makes it possible to control and initiate the DNA translocation process.

Moldovan, Radu; Wu, X. L.

2004-03-01

267

Anomalous - viscosity current drive  

DOEpatents

An apparatus and method for maintaining a steady-state current in a toroidal magnetically confined plasma. An electric current is generated in an edge region at or near the outermost good magnetic surface of the toroidal plasma. The edge current is generated in a direction parallel to the flow of current in the main plasma and such that its current density is greater than the average density of the main plasma current. The current flow in the edge region is maintained in a direction parallel to the main current for a period of one or two of its characteristic decay times. Current from the edge region will penetrate radially into the plasma and augment the main plasma current through the mechanism of anomalous viscosity. In another aspect of the invention, current flow driven between a cathode and an anode is used to establish a start-up plasma current. The plasma-current channel is magnetically detached from the electrodes, leaving a plasma magnetically insulated from contact with any material obstructions including the cathode and anode.

Stix, Thomas H. (Princeton, NJ); Ono, Masayuki (Princeton Junction, NJ)

1988-01-01

268

Anomalous Couplings at LEP2  

NASA Astrophysics Data System (ADS)

In its second phase, LEP has allowed to study four fermion processes never observed before. Results are presented on the charged triple gauge boson couplings (TGC) from the W-pair, Single W and Single ? production. The anomalous quartic gauge couplings (QGC) are constrained using production of WW?, ? bar ? ? ? and Z?? final states. Finally, limits on the neutral anomalous gauge couplings (NGC) using the Z? and ZZ production processes are also reported. All results are consistent with the Standard Model expectations.

Fayolle, D.

2003-02-01

269

Calibration of satellite-borne radiometers for measurement of the parameters of ground and celestial objects based on thermal emission in the microwave band  

SciTech Connect

A technique of calibrating satellite-borne microwave radiometers for remote measurement of the radio brightness temperatures of ground and celestial objects is considered. The composition and metrological characteristics of standard and prototype instruments developed at the central office of the All-Union Research Institute for Physicotechnical and Radiotechnical Measurements for the purpose of calibrating radiometers on the basis of radio brightness temperatures, instruments for measurement of the parameters of mirror and horn radiometer antennas, and instruments for measurement of the dynamic characteristics of radiometers are presented.

Yurchuk, E.F.; Arsaev, I.E.

1995-07-01

270

Multifrequency Microwave Radiometer Measurements of Soil Moisture  

Microsoft Academic Search

Ground-based microwave radiometer experiments were performed to investigate the effects of moisture, temperature, and roughness on microwave emission from bare soils. Measurements were made at frequencies of 0.6-0.9, 1.4, and 10.7 GHz using van-mounted radiometers to observe prepared soil sites in Kern County, CA. The sites were instrumented for monitoring soil characteristics and surface meteorological conditions. Brightness temperature variations of

Eni G. Njoku; Peggy E. O'Neill

1982-01-01

271

Polarization Effects Due to Scattering of Microwave Radiation in ihe Summer Cloudy Atmosphere  

Microsoft Academic Search

We present the results of the spectral analysis of polarization of the thermal microwave emission from the summer cloudy atmosphere at 37 and 94 GHz. A significant polarization of the microwave emission from summer clouds is revealed, which is attributed to scattering of the thermal emission from the atmosphere by melted ice crystals in the melting layer. Based on a

A. V. Troitsky; A. V. Vostokov; A. M. Osharin

2005-01-01

272

Is anomalous transport diffusive  

SciTech Connect

It has often been assumed that the anomalous transport from saturated plasma instabilities is diffusive'' in the sense that the particle flux, {Gamma}, the electron energy flux, q{sub e}, and the ion energy flux, q{sub i}, can be written in forms that are linear in the density gradient, dn/dr, the electron temperature gradient, dT{sub e}/dr, and the ion temperature gradient dT{sub i}/dr. In the simplest form, {Gamma} = {minus} D{sub n}{sup n}(dn/dr), q{sub e} = {minus} D{sub e}{sup e}n(dT{sub e}/dr), and q{sub i} = {minus}D{sub i}{sup i}n(dT{sub i}/dr). A possible generalization of this is to include so-called off-diagonal'' terms, with {Gamma} = nV{sub n} {minus} D{sub n}{sup n}(dn/dr) {minus} D{sub n}{sup e}(n/T{sub e})(dT{sub e}/dr) {minus} D{sub n}{sup i}(n/T{sub i})(dT{sub i}/dr), with corresponding forms for the energy fluxes. Here, general results for the quasilinear particle and energy fluxes, resulting from tokamak linear microinstabilities, are evaluated to assess the relative importance of the diagonal and the off-diagonal terms. A further possible generatlization is to include also contributions to the fluxes from higher powers of the gradients, specifically quadratic'' contributions proportional to (dn/dr){sup 2}, (dn/dr)(dT{sub e}/dr), and so on. A procedure is described for evaluating the corresponding coefficients, and results are presented for illustrative realistic tokamak cases. Qualitatively, it is found that the off-diagonal diffusion coefficients can be as big as the diagonal ones, and that the quadratic terms can be larger than the linear ones. The results thus strongly suggest that the commonly used diffusive'' approximation with only diagonal terms, {Gamma} = {minus}D{sub n}{sup n}(dn/dr), and correspondingly for the energy fluxes, is not adequate in practice. 9 refs., 1 tabs.

Rewoldt, G.

1989-09-01

273

Design of microwave filters  

Microsoft Academic Search

A survey of the major techniques used in the design of microwave filters is presented in this paper. It is shown that the basis for much fundamental microwave filter theory lies in the realm of lumped-element filters, which indeed are actually used directly for many applications at microwave frequencies as high as 18 GHz. Many types of microwave filters are

Ralph Levy; Richard V. Snyder; George Matthaei

2002-01-01

274

Foundations for statistical-physical precipitation retrieval from passive microwave satellite measurements. Part II: Emission-source and generalized weighting-function properties of a time-dependent cloud-radiation model  

SciTech Connect

The authors present the second part of a study on the development of a framework for precipitation retrieval from space-based passive microwave measurements using a three-dimensional time-dependent cloud model to establish the microphysical setting. The first developed the theory needed to interpret the vertically distributed radiative sources and the emission-absorption-scattering processes responsible for the behavior of frequency-dependent top-of-atomsphere brightness temperatures T[sub B]'s. The weighting-function framework is used for an analysis of land-based precipitation processes within a hail-storm simulation originally described in Part 1. The individual roles of cloud drops, rain drops, graupel particles, ice crystals, and snow aggregates on generating and modulating the frequency-dependent T[sub B]'s are examined in detail. Microwave T[sub B] measurements are highly regulated by mixtures of hydrometeors, with particular emphasis on the importance of the vertical profile structures. The authors demonstrate how scattering produces sequential, frequency-dependent, vertical break aways' of the peak amplitudes in the generalized weighting functions, thus explaining how a multichannel radiometer can be used to depth probe a precipitating cloud. They also seek to explain the extent to which 19-, 37-, and 85-GHz T[sub B]'s are responding to separate and distinct processes in precipitating cells in an unambiguous fashion, helping to understand that standard satellite frequencies are best suited to decipher certain microphysical profile features above the main rain layers and near cloud top, and ill suited for directly sensing precipitation intensity information within the main rain layers, particularly the surface rain rates. Finally, a summary of the various components of a hybrid statistical-physical rainfall algorithm used to produce liquid-ice profile information, as well as surface rain rates, is given. 24 refs., 10 figs., 5 tabs.

Mugnai, A. (Consiglio Nazionale delle Richerche, Frascati (Italy)); Smith, E.A. (Florida State Univ., Tallahassee (United States)); Tripoli, G.J. (Univ. of Wisconsin, Madison (United States))

1993-01-01

275

Examination of Broadband Coherent Synchrotron Radiation to Describe THz and Sub-THz Solar Flare Spectral Emissions  

NASA Astrophysics Data System (ADS)

Over the past decade, interest in terrestrial applications for THz radiation has grown. In particular, much effort has been directed toward development of new higher power sources. One method for producing very high power coherent broadband sub-THz to microwave radiation has been demonstrated in laboratory accelerators, where relativistic bunches of electrons are compressed and accelerated using specially designed magnetic structures. The resulting synchrotron emission from suitably compressed electron bunches exhibits a coherent enhancement for wavelengths approximately equal to or longer than the bunch length. This produces a modified synchrotron spectrum with a second peak at lower frequency associated with the coherent synchrotron radiation (CSR), with power proportional to the square of the number electrons undergoing the process. The CSR spectrum can also be produced from microbunching that is self-induced in larger bunches as a result from the interaction of the high energy electrons with the coherent component of their own radiation field. In either case, the CSR peak occurs at a frequency related to the spatial charge density of the high energy electrons. Here, we propose how the CSR mechanism may operate as a source to explain certain anomalous spectral features recently identified in the microwave to sub-THz emission of solar flare events. We outline the methods used in laboratory accelerators to produce CSR emission from high energy electron bunches, and how these methods may be related to magneto-active plasma medium where solar flare electron beams are accelerated. Utilizing estimates for active region magnetic field structures and solar flare plasma parameters, we have calculated the CSR and the ISR spectral components and compare these results to the anomalous spectrum observed from microwaves to sub-THz frequencies during the solar flare event of November 4, 2003.

Klopf, Michael; Kaufmann, P.; Raulin, J.

2010-05-01

276

Anomalous low-temperature ``post-desorption'' from solid nitrogen  

NASA Astrophysics Data System (ADS)

Anomalous low-temperature post-desorption (ALTpD) from the surface of nominally pure solid nitrogen preliminary irradiated by an electron beam was detected for the first time. The study was performed using a combination of activation spectroscopy methods--thermally stimulated exoelectron emission (TSEE) and spectrally resolved thermally stimulated luminescence (TSL)--with detection of the ALTpD yield. Charge recombination reactions are considered to be the stimulating factor for the desorption from pre-irradiated ?-phase solid nitrogen.

Savchenko, E. V.; Khyzhniy, I. V.; Uyutnov, S. A.; Ponomaryov, A. N.; Gumenchuk, G. B.; Bondybey, V. E.

2013-05-01

277

Ground-Based Microwave Investigations of Forest Plots in Italy  

Microsoft Academic Search

In this paper, we report the results of an experimental study aimed toward investigating microwave emission from forests. The experiment was carried out in 2006 on two forest stands of poplar (Populus alba) and pine (Pinus italica), using ground-based microwave radiometers at the L-, C-, X-, Ku-, and Ka-bands, in H and V polarizations. Measurements on poplar were performed on

Emanuele Santi; Simonetta Paloscia; Paolo Pampaloni; Simone Pettinato

2009-01-01

278

X-Band Microwave Properties of a Rectangular Plasma Sheet.  

National Technical Information Service (NTIS)

Detailed scans of x-band microwave transmission, reflection and noise emission of various Agile Mirror plasma sheets as a function of frequency have been performed. The reflected microwave signal from the plasma sheet is compared to that reflected from an...

D. P. Murphy R. F. Fernsler R. A. Meger R. E. Pechacek

1999-01-01

279

The Upper Atmosphere Research Satellite Microwave Limb Sounder Instrument  

Microsoft Academic Search

The microwave limb sounder (MLS) on the Upper Atmosphere Research Satellite (UARS) is the first satellite experiment using limb sounding techniques at microwave frequencies. Primary measure- ment objectives are stratospheric C10, 03, H20, temperature, and pressure. Measurements are of thermal emission: all are performed simultaneously and continuously and are not degraded by ice clouds or volcanic aerosols. The instrument has

F. T. Barath; M. C. Chavez; R. E. Cofield; D. A. Flower; M. A. Frerking; M. B. Gram; W. M. Harris; J. R. Holden; R. F. Jarnot; W. G. Kloezeman; G. J. Klose; G. K. Lau; M. S. Loo; B. J. Maddison; R. J. Mattauch; R. P. McKlnney; G. E. Peckham; H. M. Pickett; G. Siebes; F. S. Soltis; R. A. Suttie; J. A. Tarsala; J. W. Waters; W. J. Wilson

1993-01-01

280

Greener steel maldng process by microwave irradiation with discharges  

Microsoft Academic Search

Highly pure pig irons were produced from powdered iron ores and carbons in a multimode microwave reactor. Microwaves create two different steps that enhance chemical reactions at the grain boundaries very rapidly to finish the reduction process. The visible light spectroscopic monitored the progress of the reactions. The powders absolve and radiate the continuous spectrum of blackbody emission under the

M. Sato; K. Nagata; A. Matsubara; S. Takayama

2008-01-01

281

New microwave concepts based on carbon nano tubes  

Microsoft Academic Search

The paper discusses microwave-device concepts based on carbon nanotubes. First, the physical properties of the carbon nanotubes are briefly described. Then, field emission devices, quantum electronic devices, microwave passive and active devices all based on carbon nanotubes are in detail described and their performance evaluated.

H. L. Hartangel

2008-01-01

282

Anomalous Transport:. A Mathematical Framework  

NASA Astrophysics Data System (ADS)

We develop a mathematical framework allowing to study anomalous transport in homogeneous solids. The main tools characterizing the anomalous transport properties are spectral and diffusion exponents associated to the covariant Hamiltonians describing these media. The diffusion exponents characterize the spectral measures entering in Kubo's formula for the conductivity and hence lead to anomalies in Drude's formula. We give several formulas allowing to calculate these exponents and treat, as an example, Wegner's n-orbital model as well as the Anderson model in coherent potential approximation.

Schulz-Baldes, H.; Bellissard, J.

283

Microwave Remote Sensing of Planetary Atmospheres: From Staelin and Barrett to the Nasa Juno Mission  

Microsoft Academic Search

Early seminal contributions by Staelin helped initiate the field of microwave remote sensing as a key tool for the study of planetary atmospheres. Recent studies of the microwave emission from the neutral atmosphere of Venus have been used to identify the abundance and spatial distribution of microwave absorbing constituents such as sulfuric acid vapor and sulfur dioxide. A new mission

Paul G. Steffes; Bryan M. Karpowicz

2008-01-01

284

Surface and Bulk Characteristics of Cesium Iodide (CsI) coated Carbon (C) Fibers for High Power Microwave (HPM) Field Emission Cathodes  

NASA Astrophysics Data System (ADS)

CsI coated C fibers [1] are promising field emission cathodes for HPM applications. Ab initio computational modeling has shown that atomically-thin CsI coatings reduce the work function of C substrates by a surface dipole mechanism [2]. Characterization measurements of the composition and morphology of the CsI-coated C fibers are underway for determining the properties and characteristics of the following important regions of the fiber: (i) the surface on the tip of the fiber where the majority of electron emission is believed to occur, (ii) the surface covering the body of the fiber and its role on the emission properties of the system, and (iii) the interior volume of the fiber and its effects on the CsI surface re-supply process and rate. The results will be interpreted in terms of surface electronic properties and theoretical electron emission models. [1]D. Shiffler, et al., Phys. Plasmas 11 (2004) 1680. [2]V.Vlahos et al., Appl. Phys. Lett. 91 (2007) 144102.

Vlahos, Vasilios; Morgan, Dane; Booske, John H.; Shiffler, Don

2008-11-01

285

Sea Surface Signature of Tropical Cyclones Using Microwave Remote Sensing.  

National Technical Information Service (NTIS)

Measuring the sea surface during tropical cyclones (TC) is challenging due to severe weather conditions that prevent shipboard measurements and clouds which mask the sea surface for visible satellite sensors. However, sea surface emission in the microwave...

B. Kil D. Burrage J. Wesson S. Howden

2013-01-01

286

Clustering based anomalous transaction reporting  

Microsoft Academic Search

Anti-money laundering (AML) refers to a set of financial and technological controls that aim to combat the entrance of dirty money into financial systems. A robust AML system must be able to automatically detect any unusual\\/anomalous financial transactions committed by a customer. The paper presents a hybrid anomaly detection approach that employs clustering to establish customers’ normal behaviors and uses

Asma S. Larik; Sajjad Haider

2011-01-01

287

Comparative study of a beenakker cavity and a surfatron in combination with electrothermal evaporation from a tungsten coil for microwave plasma optical emission spectrometry (MIP-AES).  

PubMed

Microwave induced plasmas, sustained in a Beenakker resonator and a surfatron, respectively, are used to excite vapours released by electrothermal evaporation of solutions from a tungsten coil. The analytical figures of merit of AES for two easily volatilized elements (Cu, Cd) are compared for argon MIP operated in the two resonators under optimized conditions. In the Beenakker resonator a 1-filament plasma was produced at an argon flow of 0.45 l./min and a forward power of 50 W. In the surfatron a 2-filament plasma with 2.44 l./min argon and a forward power of 130 W was used. The detection limits for Cu and Cd with the surfatron are lower than those obtained with the Beenakker resonator and are in the range 10-20 ng/ml. Also interferences arising from an easily ionized element such as Na are lower with the surfatron than with the beenakker resonator. The linear dynamic ranges in the case of the surfatron are also superior and extend over three decades of concentration. PMID:18965230

Richts, U; Broekaert, J A; Tschöpel, P; Tölg, G

1991-08-01

288

47 CFR 101.111 - Emission limitations.  

Code of Federal Regulations, 2012 CFR

...101.111 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.111 Emission limitations. (a) The mean power of emissions must be...

2012-10-01

289

Venus Highland Anomalous Reflectivity  

NASA Astrophysics Data System (ADS)

Maxwell Montes was one of several unusually bright areas identified from early Venus radar backscatter observations. Pioneer Venus' orbiting radar associated low emissivity with the bright areas and established a correlation between reflectivity and altitude. Magellan, using an oblique bistatic geometry, showed that the bright surface dielectric constant was not only large but also imaginary -- i.e., the material was conducting, at least near Cleopatra Patera (Pettengill et al., Science, 272, 1996). Venus Express (VEX) repeated Magellan's bistatic observations over Maxwell, using the more conventional circular polarization carried by most spacecraft. Although VEX signal-to-noise ratio was lower than Magellan's, echoes were sufficiently strong to verify the Magellan conclusions near Cleopatra (see J. Geophys. Res., 114, E00B41, doi:10.1029/2008JE003156). Only about 40% of the surface at Cleopatra scatters specularly, opening the Fresnel (specular) interpretation model to question. Elsewhere in Maxwell, the specular percentage may be even lower. Nonetheless, the echo polarization is reversed throughout Maxwell, a result that is consistent with large dielectric constants and difficult to explain without resorting qualitatively (if not quantitatively) to specular models. VEX was scheduled to explore other high altitude regions when its S-Band (13-cm wavelength) radio system failed in late 2006, so further probing of high altitude targets awaits arrival of a new spacecraft.

Simpson, Richard A.; Tyler, G. L.; Häusler, B.; Mattei, R.; Patzold, M.

2009-09-01

290

Cosmological origin of anomalous radio background  

NASA Astrophysics Data System (ADS)

The ARCADE 2 collaboration has reported a significant excess in the isotropic radio background, whose homogeneity cannot be reconciled with clustered sources. This suggests a cosmological origin prior to structure formation. We investigate several potential mechanisms and show that injection of relativistic electrons through late decays of a metastable particle can give rise to the observed excess radio spectrum through synchrotron emission. However, constraints from the cosmic microwave background (CMB) anisotropy, on injection of charged particles and on the primordial magnetic field, present a challenge. The simplest scenario is with a gtrsim9 GeV particle decaying into e+e- at a redshift of z ~ 5, in a magnetic field of ~ 5?G, which exceeds the CMB B-field constraints, unless the field was generated after decoupling. Decays into exotic millicharged particles can alleviate this tension, if they emit synchroton radiation in conjunction with a sufficiently large background magnetic field of a dark U(1)' gauge field.

Cline, James M.; Vincent, Aaron C.

2013-02-01

291

Determination of butyl- and phenyltin compounds in human urine by HS-SPME after derivatization with tetraethylborate and subsequent determination by capillary GC with microwave-induced plasma atomic emission and mass spectrometric detection.  

PubMed

A headspace solid-phase micro-extraction (HS-SPME) method was developed and optimized for gas chromatographic separation and determination of commonly found organotin compounds in human urine after potential exposure. Butyl- and phenyltin compounds were in situ derivatized to ethylated derivatives by sodium tetraethylborate (NaBEt(4)) directly in the urine matrix. The relevant parameters affecting the yield of the SPME procedure were examined using tetrabutyltin as internal standard. The method was optimized for direct use in the analysis of undiluted human urine samples and mono-, di- and tri-substituted butyl- and phenyltin compounds could be determined after a 15-min headspace extraction time at room temperature. The selectivity of the microwave-induced plasma atomic emission detector (MIP-AED) as an element specific detector in combination with the relatively selective sample preparation technique of HS-SPME allowed the interference-free detection of the organotin compounds in all cases. A quadrupole mass spectrometer was used in parallel experiments as a detector for the confirmation of the identity molecular structure of the eluted compounds. The performance characteristics of the developed method are given for the determination of mixtures of these compounds. Finally the proposed method was applied to the analysis of several human urine samples. PMID:19203626

Zachariadis, G A; Rosenberg, E

2008-12-11

292

Microwave Device Investigations.  

National Technical Information Service (NTIS)

Materials, devices and novel schemes for generation, amplification and detection of microwave and millimeter wave energy are studied. Considered are: (1) Schottky-barrier microwave devices; (2) intermodulation products in IMPATT diode amplifiers; and (3) ...

K. K. Choudhury G. I. Haddad S. P. Kwok N. A. Masnari R. J. Trew

1972-01-01

293

Microwave Radiation and Thermoregulation.  

National Technical Information Service (NTIS)

Low intensity microwave fields alter normal responses, both autonomic and behavioral, that regulate the body temperature. Using the squirrel monkey as an animal model, we have quantified the minimal intensity of 2450 MHz CW microwaves that will lower meta...

E. R. Adair

1981-01-01

294

Surface identification using satellite microwave radiometers  

Microsoft Academic Search

The use of satellite microwave radiometers for identifying natural surfaces is analyzed. A retrieval technique is developed by considering the related mixed-pixel problem where two or more surfaces are contained within the viewing area. At a given frequency &ogr;, the emissivity measurement ?(&ogr;) depends on the fractional amounts f n and a priori emissivities ?n(&ogr;) where ?(&ogr;)=??n(&ogr;)fn. In applications involving

NORMAN C. GRODY

1988-01-01

295

Measurements of human body microwave radiation  

Microsoft Academic Search

Major problems of registering microwave radiation of human body have been considered. It is pointed out that they are caused by at least three factors which may considerably influence the experimental results and their interpretation, namely: (1) properties of the radiation (their low intensity primarily); (2) features of measurements that implement waveguide techniques; (3) peculiar features of the emission medium

G. V. Ponezha; S. G. Ponezha; A. I. Nizhelskaya

2003-01-01

296

MICROWAVE AND HYBRID TECHNOLOGIES IN MEAT PRESERVATION  

Microsoft Academic Search

One of the products from secondary meat processing industries is jerky, which has good market value of $250 million per annum. Jerky is one of the North American dried meat product and it has been processed in traditional methods like smoke housing or home dehydrators which takes 6-10 hr for processing. As a first attempt, application of non-emissive clean microwave

Ignaci Victoria Thiagarajan

297

Anomalous absorption in a-type asymmetric top molecules in cosmic objects  

NASA Astrophysics Data System (ADS)

Since the detection of the first molecule OH in cosmic objects in 1963, scientists got interested in identification of molecules in the cosmic objects. By now more than 170 molecules have been identified. In order to know about the physical conditions prevailing in the cool cosmic objects and about the chemical reactions going on there, scientists are interested in identification of as many molecules as possible. In some molecular clouds, the kinetic temperature is very low, 10 - 20 K. For such objects, anomalous absorption, i.e., the absorption against the cosmic microwave background, may play an important role for identification of molecules. The transition 111 - 110 at 4.829 GHz of H_2CO was the first one showing the anomalous absorption in the cosmic objects. The molecule H_2CS also has been identified in the cosmic objects. We have discussed about the anomalous absorption of 111 - 110 transition in a-type asymmetric top molecules. For the investigation, the required parameters are the radiative and collisional transition probabilities. We can calculate radiative transition probabilities between the rotational levels. Calculation of collisional rates is a tedious job. In absence of accurate collisional rates, we can investigated the anomalous absorption in a qualitative manner by using the scaled values for collisional rates. We find that anomalous absorption of 111 - 110 transition is possible, provided collisional rates satisfy the required condition.

Chandra, Suresh

298

Microwave heating of foodstuffs  

Microsoft Academic Search

The temperature distribution in a product submitted to microwave radiation is governed by the interaction and absorption of radiation by the medium and the accompanying transport processes due to the dissipation of electromagnetic energy into heat. Thus, modeling of microwave heating involves coupling the models for microwave power absorption and temperature distribution inside the product. In this study, a model

M. E. C. Oliveira; A. S. Franca

2002-01-01

299

Microwave Workshop for Windows.  

ERIC Educational Resources Information Center

|"Microwave Workshop for Windows" consists of three programs that act as teaching aid and provide a circuit design utility within the field of microwave engineering. The first program is a computer representation of a graphical design tool; the second is an accurate visual and analytical representation of a microwave test bench; the third is a…

White, Colin

1998-01-01

300

Microwave interaction with air  

Microsoft Academic Search

Microwave breakdown studies of gaseous elements have been carried out extensively over a wide range of pressures and for several microwave frequencies using CW and pulsed radiation sources. The main emphasis in these studies was on the determination of the breakdown power threshold and its dependence on the gas pressure and the microwave frequency. The coupling of mircowave energy into

W. M. Bollen; D. Pershing

1985-01-01

301

Microwave Workshop for Windows.  

ERIC Educational Resources Information Center

"Microwave Workshop for Windows" consists of three programs that act as teaching aid and provide a circuit design utility within the field of microwave engineering. The first program is a computer representation of a graphical design tool; the second is an accurate visual and analytical representation of a microwave test bench; the third is a more…

White, Colin

1998-01-01

302

Radiofrequency and microwave radiation  

Microsoft Academic Search

This paper deals with the controversy and disagreement surrounding the issue of harm from radiofrequency (RF) and microwaves. The radiation standards adopted by different countries are quite divergent with the least strict standard for microwave exposure differing from the most strict by a factor of 100. Among the most powerful sources of RF and microwave radiation are radar systems used

Hileman

1982-01-01

303

Anomalous diffusion and continuum percolation  

NASA Astrophysics Data System (ADS)

Anomalous diffusion for continuum percolation is simulated by considering systems of randomly distributed circles and spheres. Universal behavior is obtained for the case of equal local conductances and nonuniversal behavior for diverging distributions of the local conductances. Diffusion in the continuum has a behavior consistent with that of other transport properties in the continuum. In addition, the results suggest that different algorithms for diffusion, which differ only in the random walker sitting times, are equivalent.

Wagner, N.; Balberg, I.

1987-10-01

304

Anomalous sounds from the entry of meteor fireballs.  

PubMed

A very bright fireball observed over New South Wales in 1978 produced anomalous sounds clearly audible to some of the observers. An investigation of the phenomenon indicates that bright fireballs radiate considerable electromagnetic energy in the very-low-frequency (VLF) region of the spectrum. A mechanism for the production of VLF emissions from the highly energetic wake turbulence of the fireball is proposed. Trials with human subjects revealed a very extended range of thresholds for the perception of electrically excited sounds among a sample population, particularly when the VLF electric field excites surface acoustic waves in surrounding objects. This fact, together with variable propagation effects and local conditions, can account for the sporadic distribution of reports of anomalous sounds from fireballs and auroras. PMID:17751127

Keay, C S

1980-10-01

305

Microwave radiometry and applications  

NASA Astrophysics Data System (ADS)

The radiometry in general is a method of detecting the radiation of matter. All material bodies and substances radiate energy in the form of electromagnetic waves according to Planck s Law. The frequency spectrum of such thermal radiation is determined, beyond the properties of a blackbody, by the emissivity of surfaces and by the temperature of a particular body. Also, its reflectivity and dispersion take part. Investigating the intensity of radiation and its spectral distribution, one may determine the temperature and characterize the radiating body as well as the ambient medium, all independently of distance. With the above possibilities, the radiometry represents a base of scientific method called remote sensing. Utilizing various models, temperature of distant bodies and images of observed scenes can be determined from the spatial distribution of radiation. In this method, two parameters are of paramount importance: the temperature resolution, which flows out from the detected energy, and the spatial resolution (or, angular resolution), which depends upon antenna size with respect to wavelength. An instrument usable to conduct radiometric observations thus consists of two basic elements: a detector or radiometer, which determines the temperature resolution, and an antenna which determines the angular or spatial resolution. For example, a photographic camera consists of an objective lens (antenna) and of a sensitive element (a film or a CCD). In remote sensing, different lenses and reflectors and different sensors are employed, both adjusted to a particular spectrum region in which certain important features of observed bodies and scenes are present: frequently, UV and IR bands are used. The microwave radiometry utilizes various types of antennas and detectors and provides some advantages in observing various scenes: the temperature resolution is recently being given in milikelvins, while the range extends from zero to millions of Kelvins. Microwaves also offer a chance to penetrate surfaces of non-metallic objects down to some wavelengths, by which it is advantageous in certain applications over e.g. IR waves. An extreme example of capabilities of the microwave radiometry is found in radio astronomy, where it determines temperatures and spectral features of bodies so remote that their distance from us is measured in millions of light years. Other apparatus serve in remote observation of Earth s resources: soils, water regions and atmosphere. Similar systems also have found applications in medical studies of human body, e.g. in cancer and inflammation diagnostics. The paper presents a background of the radiometric method, comments to equipment design and outlines some of the applications.

Polívka, Ji?í

1995-09-01

306

Microwave hemorrhagic stroke detector  

DOEpatents

The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device is based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stroke in human or animal patients as well as for the detection of hemorrhage within a patient's body.

Haddad, Waleed S. (Dublin, CA); Trebes, James E. (Livermore, CA)

2002-01-01

307

Microwave hemorrhagic stroke detector  

DOEpatents

The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device is based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stoke in human or animal patients as well as for the detection of hemorrhage within a patient's body.

Haddad, Waleed S. (Dublin, CA); Trebes, James E. (Livermore, CA)

2007-06-05

308

Microwave hemorrhagic stroke detector  

SciTech Connect

The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device is based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stroke in human or animal patients as well as for the detection of hemorrhage within a patient's body.

Haddad, Waleed S. (Dublin, CA); Trebes, James E. (Livermore, CA)

2002-01-01

309

Microwave hemorrhagic stroke detector  

SciTech Connect

The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device is based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stoke in human or animal patients as well as for the detection of hemorrhage within a patient's body.

Haddad, Waleed S. (Dublin, CA); Trebes, James E. (Livermore, CA)

2007-06-05

310

Decimetric Spike Bursts versus Microwave Continuum  

NASA Astrophysics Data System (ADS)

We analyze properties of decimetric spike bursts occurring simultaneously with microwave gyrosynchrotron continuum bursts. We found that all of the accompanying microwave bursts were highly polarized in the optically thin range. The sense of polarization of the spike clusters is typically the same as that of the optically thin gyrosynchrotron emission, implying preferential extraordinary wave-mode spike polarization. Optically thick spectral indices of the continuum in spike-producing events were not observed to be larger than 2.5, suggesting low or absent Razin suppression. This implies that the plasma frequency-to-gyrofrequency ratio is systematically lower in the spike-producing bursts than in other bursts. The spike cluster flux density is found to be tightly correlated with the high-frequency spectral index of the microwave continuum for each event, while the flux-to-flux correlation may not be present. We discovered strong evidence that the trapped fast electrons producing the microwave gyrosynchrotron continuum have an anisotropic pitch-angle distribution of the loss cone type in the spike-producing bursts. The spike clusters are mainly generated when the trapped electrons have the hardest and the most anisotropic distributions. The new properties are discussed against the currently available ideas about emission processes and models for spike generation. We conclude that the findings strongly support the electron cyclotron maser mechanism of spike emission, with characteristics agreeing with expectations from the local-trap model.

Fleishman, Gregory D.; Gary, Dale E.; Nita, Gelu M.

2003-08-01

311

Anomalous phosphenes in ocular protontherapy  

NASA Astrophysics Data System (ADS)

We have undertaken a clinical ground study of proton-induced light flashes (phosphenes). Patients treated at the Institut Curie - Centre de Protonthérapie in Orsay, France, received radiation therapy to cure ocular and skull-base cancers. Sixty percent of the patients treated for choroidal melanomas using 73 MeV protons report anomalous phosphenes. Delivering a radiation dose on the retina only is not sufficient to trigger the light flash. The present study may be the first indication of phosphenes triggered by protons of few tens of MeV.

Khan, E.; Maréchal, F.; Dendale, R.; Mabit, C.; Calugaru, V.; Desjardin, L.; Narici, L.

2010-04-01

312

Microwave System for the Microwave Tokamak Experiment (MTX).  

National Technical Information Service (NTIS)

The microwave system for the Microwave Tokamak Experiment (MTX) will include part of the Lower Hybrid Heating (LHH) system used at Massachusetts Institute of Technology (MIT) on the Alcator machine and the new Free Electron Laser (FEL) microwave system be...

B. Felker W. Ferguson J. Heefner K. Krause M. Makowski

1987-01-01

313

Considerations for Microwave Remote Sensing of Ocean-Surface Salinity  

Microsoft Academic Search

Parametric calculations of the microwave emission from the ocean surface are presented to determine the optimum electromagnetic wavelength for measuring salinity. At 800 MHz, a target accuracy of 240 parts per million is within the state of the art provided that emission due to surface roughness is negligible, or correctable, and that the error resulting from galactic radiation can be

Calvin T. Swift; Robert E. Mcintosh

1983-01-01

314

A review of applications of microwave radiometry to oceanography  

Microsoft Academic Search

The thermal microwave radiation from the ocean surface as seen from space is a function of the surface temperature and wind speed and is modified by liquid water and water vapor in the intervening atmosphere. Further, if the ocean surface is frozen, the emissivity is drastically increased and the effect of the intervening atmosphere is generally negligible. The emissivity of

Thomas T. Wilheit

1978-01-01

315

Scientists Detect Radio Emission from Rapidly Rotating Cosmic Dust Grains  

NASA Astrophysics Data System (ADS)

Astronomers have made the first tentative observations of a long-speculated, but never before detected, source of natural radio waves in interstellar space. Data from the National Science Foundation's 140 Foot Radio Telescope at the National Radio Astronomy Observatory in Green Bank, W.Va., show the faint, tell-tale signals of what appear to be dust grains spinning billions of times each second. This discovery eventually could yield a powerful new tool for understanding the interstellar medium - the immense clouds of gas and dust that populate interstellar space. The NRAO 140 Foot Radio Telescope The NRAO 140-Foot Radio Telescope "What we believe we have found," said Douglas P. Finkbeiner of Princeton University's Department of Astrophysics, "is the first hard evidence for electric dipole emission from rapidly rotating dust grains. If our studies are confirmed, it will be the first new source of continuum emission to be conclusively identified in the interstellar medium in nearly the past 20 years." Finkbeiner believes that these emissions have the potential in the future of revealing new and exciting information about the interstellar medium; they also may help to refine future studies of the Cosmic Microwave Background Radiation. The results from this study, which took place in spring 1999, were accepted for publication in Astrophysical Journal. Other contributors to this paper include David J. Schlegel, department of astrophysics, Princeton University; Curtis Frank, department of astronomy, University of Maryland; and Carl Heiles, department of astronomy, University of California at Berkeley. "The idea of dust grains emitting radiation by rotating is not new," comments Finkbeiner, "but to date it has been somewhat speculative." Scientists first proposed in 1957 that dust grains could emit radio signals, if they were caused to rotate rapidly enough. It was believed, however, that these radio emissions would be negligibly small - too weak to be of any impact to current radio astronomy research, and the idea was largely forgotten. In the 1990s this perception began to change when scientists and engineers designed sensitive instruments to detect the faint afterglow of the Big Bang, which is seen in the Universe as the Cosmic Microwave Background Radiation. While making detailed maps of this faint and cold radiation, scientists also detected signals at approximately the same wavelength and intensity as the background radiation, but clearly emanating from within the Milky Way's galactic plane. The researchers expected to detect some emission from the Milky Way, but what they encountered was much brighter than anticipated. This discovery caused some concern among researchers because of the need to have a very clear "window" on the Universe to study the background radiation in great detail. If there were a source of radio emission in our own galactic "back yard," then studies of the microwave background radiation would need to recognize these emissions and correct for them. "We want to be clear, however, that nothing we have found invalidates the current interpretation of the Cosmic Microwave Background Radiation," assured Finkbeiner. "Nobody has done anything wrong in neglecting these signals - so far." Scientists considered several plausible mechanisms for this anomalous emission, but these theories failed to explain the observed spatial distribution of this emission across the sky. This predicament prompted theorists to rethink the spinning dust idea, leading to a 1998 model by Bruce Draine (Princeton University) and Alex Lazarian (University of Wisconsin), which proposed rotational dust-grain emission as an important mechanism. Draine and Lazarian assumed that small dust grains, perhaps having no more than 100 atoms each, would populate many interstellar dust clouds in the Galaxy. Each grain would have a small electric dipole and would therefore react to the charged ions that race through the clouds at tremendous speeds. As an ion either strik

2001-11-01

316

Measurements of plasma potential in high-pressure microwave plasmas.  

PubMed

Plasma potential of a high-pressure ( approximately 1 Torr) microwave-generated argon plasma is measured using a Langmuir probe and a cold emissive probe. The operation of a hot emissive probe in a high-pressure plasma has been very difficult due to frequent burn-outs and significantly reduced lifetime of the probe filament, which, in turn, limits the possibility of collecting a wide range of data. The I-V characteristics from both Langmuir and emissive probes are interpreted using the collisionless probe theory since the collision correction factor is not very significant. The plasma potential determined from both Langmuir and cold emissive probe characteristics agrees well with one another and is observed to be dependent on the operating gas pressure but relatively unchanged as a function of the microwave power. An average plasma potential determined over the operating range of microwave powers varies nonlinearly with the gas pressure. PMID:19405659

Tarasova, A V; Podder, N K; Clothiaux, E J

2009-04-01

317

Use of the Reciprocity Theorem and Mapping Theorems in Locating Anomalous Air Pollution Sources  

Microsoft Academic Search

A method of using one or more ground-level air pollution transducers to detect anomalous emission from a fixed point source of air pollution is described. It is assumed a source can be identified by two position variables and three operating parameters. It is possible to spot the source position within a region A ¿ E2 if the operating parameters are

Rex A. Naden; J. Venn Leeds; Paul E. Pfeiffer

1973-01-01

318

Microwave Heating for Road Maintenance.  

National Technical Information Service (NTIS)

This report describes a two-year program during which a high power microwave generator was designed, fabricated, and tested. The microwave road patch system consists of a microwave power generating system and an associated cooling unit and applicator. Thi...

L. L. Boyko E. H. Lederer R. G. Sawyer

1976-01-01

319

Anomalous edge transport in the quantum anomalous Hall state.  

PubMed

We predict by first-principles calculations that thin films of a Cr-doped (Bi,Sb)2Te3 magnetic topological insulator have gapless nonchiral edge states coexisting with the chiral edge state. Such gapless nonchiral states are not immune to backscattering, which would explain dissipative transport in the quantum anomalous Hall (QAH) state observed in this system experimentally. Here, we study the edge transport with both chiral and nonchiral states by the Landauer-Büttiker formalism and find that the longitudinal resistance is nonzero, whereas Hall resistance is quantized to h/e2. In particular, the longitudinal resistance can be greatly reduced by adding an extra floating probe even if it is not used, while the Hall resistance remains at the quantized value. We propose several transport experiments to detect the dissipative nonchiral edge channels. These results will facilitate the realization of pure dissipationless transport of QAH states in magnetic topological insulators. PMID:24010462

Wang, Jing; Lian, Biao; Zhang, Haijun; Zhang, Shou-Cheng

2013-08-20

320

High Power, High Sensitivity Microwave Calorimeter.  

National Technical Information Service (NTIS)

A microwave calorimeter is disclosed for substantially measuring the total microwave energy in an applied microwave pulse. The microwave calorimeter includes: a housing having a highly reflective interior surface, a microwave device disposed in the housin...

F. M. Mako J. A. Pasour

1989-01-01

321

Dressed-Quark Anomalous Magnetic Moments  

SciTech Connect

Perturbation theory predicts that a massless fermion cannot possess a measurable magnetic moment. We explain, however, that the nonperturbative phenomenon of dynamical chiral symmetry breaking generates a momentum-dependent anomalous chromomagnetic moment for dressed light quarks, which is large at infrared momenta, and demonstrate that consequently these same quarks also possess an anomalous electromagnetic moment with similar magnitude and opposite sign.

Chang Lei [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Liu Yuxin [Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Roberts, Craig D. [Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2011-02-18

322

Parallel Telescope Observations of Anomalous Refraction  

Microsoft Academic Search

We present the results of an observing campaign at the US Naval Observatory, Flagstaff Station examining the relationship between anomalous refraction and coherent motions in the atmosphere. Anomalous refraction is a quasi-periodic error in astrometric positions with characteristic timescales of minutes to tens of minutes and amplitudes of up to several tenths of an arcsecond. Three dissimilar telescopes observed the

Suzanne Taylor; J. McGraw; P. Zimmer; J. Pier

2009-01-01

323

Anomalous transport studies for heliotron\\/torsatron  

Microsoft Academic Search

Recently Heliotron E experiments showed the electron thermal transport is anomalous for almost all plasma parameters particularly in the edge plasmas. For the heliotron\\/torsatron configuration with a bad average curvature, g mode turbulence is the most probable candidate to explain the edge anomalous transport. Another candidate is the collisional drift wave turbulence. Fluid model equations were developed describing a drift

M. Wakatani; M. Yagi; H. Sugama; K. Watanabe; A. Hasegawa; B. G. Hong; W. Horton

1990-01-01

324

The microwave market  

SciTech Connect

As superconductors move from the laboratory to the marketplace, it becomes more important for researchers and manufacturers to understand the markets for this technology. The large market for microwave systems represents a major opportunity for high-T/sub c/ superconductors. Conductor losses are a primary design limitation in conventional microwave systems. The low losses of superconductors at microwave frequencies will allow component designers and system designers to improve their products in many ways. The most important market segments for microwave systems are outlined in this discussion.

Bybokas, J. (Superconducting Technology, Inc., Mountain View, CA (USA))

1989-07-01

325

Microwave enhanced diffusion  

SciTech Connect

The observation of more rapid reaction and/or sintering during microwave processing of ceramics has lead to speculation that microwave processing results in enhanced diffusion.'' The loss mechanisms by which microwaves interact with a crystal lattice have been reviewed. These mechanisms were evaluated with regard to the atomic theory of diffusion. The potential for these loss mechanisms to influence atomic diffusion, and thus produce enhancement will be discussed. Existing evidence, both direct and indirect, regarding microwave enhanced diffusion has been reviewed and will be discussed along with recent experimental data. 15 refs., 5 figs.

Katz, J.D.; Blake, R.D. (Los Alamos National Lab., NM (USA)); Kenkre, V.M. (New Mexico Univ., Albuquerque, NM (USA))

1991-01-01

326

Lossless anomalous dispersion and an inversionless gain doublet via dressed interacting ground states  

SciTech Connect

Transparent media exhibiting anomalous dispersion have been of considerable interest since Wang, Kuzmich, and Dogariu [Nature 406, 277 (2000)] first observed light propagate with superluminal and negative group velocities without absorption. Here, we propose an atomic model exhibiting these properties, based on a generalization of amplification without inversion in a five-level dressed interacting ground-state system. The system consists of a {Lambda} atom prepared as in standard electromagnetically induced transparency (EIT), with two additional metastable ground states coupled to the {Lambda} atom ground states by two rf-microwave fields. We consider two configurations by which population is incoherently pumped into the ground states of the atom. Under appropriate circumstances, we predict a pair of new gain lines with tunable width, separation, and height. Between these lines, absorption vanishes but dispersion is large and anomalous. The system described here is a significant improvement over other proposals in the anomalous dispersion literature in that it permits additional coherent control over the spectral properties of the anomalous region, including a possible 10{sup 4}-fold increase over the group delay observed by Wang, Kuzmich, and Dogariu.

Weatherall, James Owen [Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030 (United States); Department of Mathematical Sciences, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030 (United States); Department of Logic and Philosophy of Science, University of California Irvine, 3151 Social Science Plaza A, Irvine, California 92697 (United States); Search, Christopher P. [Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030 (United States)

2010-02-15

327

IMPROVING THE MODEL OF EMISSION FROM SPINNING DUST: EFFECTS OF GRAIN WOBBLING AND TRANSIENT SPIN-UP  

SciTech Connect

Observations continue to support the interpretation of the anomalous microwave foreground as electric dipole radiation from spinning dust grains as proposed by Draine and Lazarian. In this paper, we present a refinement of the original model by improving the treatment of a number of physical effects. First, we consider a disk-like grain rotating with angular velocity at an arbitrary angle with respect to the grain symmetry axis (i.e., grain wobbling) and derive the rotational damping and excitation coefficients arising from infrared emission, plasma-grain interactions, and electric dipole emission. The angular velocity distribution and the electric dipole emission spectrum for disk-like grains is calculated using the Langevin equation, for cases both with and without fast internal relaxation. Our results show that for fast internal relaxation, the peak emissivity of spinning dust, compared to earlier studies, increases by a factor of {approx}2 for the warm neutral medium (WNM), the warm ionized medium (WIM), the cold neutral medium (CNM), and the photodissociation region, and by a factor {approx}4 for reflection nebulae. The frequency at the emission peak also increases by factors {approx}1.4 to {approx}2 for these media. Without internal relaxation, the increase of emissivity is comparable, but the emission spectrum is more extended to higher frequency. The increased emission results from the non-sphericity of grain shape and from the anisotropy in damping and excitation along directions parallel and perpendicular to the grain symmetry axis. Second, we provide a detailed numerical study including transient spin-up of grains by single-ion collisions. The range of grain size in which single-ion collisions are important is identified. The impulses broaden the emission spectrum and increase the peak emissivity for the CNM, WNM, and WIM, although the increases are not as large as those due to the grain wobbling. In addition, we present an improved treatment of rotational excitation and damping by infrared emission.

Hoang, Thiem; Lazarian, A. [Astronomy Department, University of Wisconsin, Madison, WI 53706 (United States); Draine, B. T. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

2010-06-01

328

Effects of Microwave Radiation on Oil Recovery  

NASA Astrophysics Data System (ADS)

A variety of oil recovery methods have been developed and applied to mature and depleted reservoirs in order to improve the efficiency. Microwave radiation oil recovery method is a relatively new method and has been of great interest in the recent years. Crude oil is typically co-mingled with suspended solids and water. To increase oil recovery, it is necessary to remove these components. The separation of oil from water and solids using gravitational settling methods is typically incomplete. Oil-in-water and oil-water-solid emulsions can be demulsified and separated into their individual layers by microwave radiation. The data also show that microwave separation is faster than gravity separation and can be faster than conventional heating at many conditions. After separation of emulsion into water and oil layers, water can be discharged and oil is collected. High-frequency microwave recycling process can recover oil and gases from oil shale, residual oil, drill cuttings, tar sands oil, contaminated dredge/sediments, tires and plastics with significantly greater yields and lower costs than are available utilizing existing known technologies. This process is environmentally friendly, fuel-generating recycler to reduce waste, cut emissions, and save energy. This paper presents a critical review of Microwave radiation method for oil recovery.

Esmaeili, Abdollah

2011-12-01

329

Microwave detection of air showers with the MIDAS experiment  

NASA Astrophysics Data System (ADS)

Microwave emission from Extensive Air Showers could provide a novel technique for ultra-high energy cosmic rays detection over large area and with 100% duty cycle. We describe the design, performance and first results of the MIDAS (MIcrowave Detection of Air Showers) detector, a 4.5 m parabolic dish with 53 feeds in its focal plane, currently installed at the University of Chicago.

Privitera, Paolo; Alekotte, I.; Alvarez-Muñiz, J.; Berlin, A.; Bertou, X.; Bogdan, M.; Bohá?ová, M.; Bonifazi, C.; Carvalho, W. R.; de Mello Neto, J. R. T.; Facal San Luis, P.; Genat, J. F.; Hollon, N.; Mills, E.; Monasor, M.; Reyes, L. C.; Rouille D'Orfeuil, B.; Santos, E. M.; Wayne, S.; Williams, C.; Zas, E.

2011-03-01

330

Microwaving in F-18 Chemistry: Quirks and Tweaks  

Microsoft Academic Search

Since the late 1980s, microwave dielectric heating has been used to speed up chemical transformations, also in radiolabeling\\u000a tracers for positron emission tomography. In addition to shorter reaction times, higher yields, cleaner product mixtures and\\u000a improved reproducibility have also been obtained for reactions involving polar components that require heating at elevated\\u000a temperatures. The conditions used in microwave chemistry can differ

S. Stone-Elander; N. Elander; J.-O. Thorell; A. Fredriksson

331

Microwave\\/Infrared-Laser Processing of Material for Solar Energy  

Microsoft Academic Search

\\u000a Several approaches have been studied for microwave material processing for solar energy utilization such as upgrading the\\u000a photocatalytic activity of TiO2, and improvement of efficiency in polymer solar cell. Recently, we observed the emission of zinc and oxygen plasmas from\\u000a ZnO ceramics during intense absorption of microwaves as well as the deposition of zinc and zinc oxide films. This finding

Taro Sonobe; Kyohei Yoshida; Kan Hachiya; Toshiteru Kii; Hideaki Ohgaki

332

Satellite microwave observations of the Utah Great Salt Lake Desert  

Microsoft Academic Search

Microwave data acquired over the Great Salt Lake Desert area by sensors aboard Skylab and Nimbus 5 indicate that the microwave emission and backscatter were strongly influenced by contributions from subsurface layers of sediment saturated with brine. This phenomenon was observed by Skylab's S-194 radiometer operating at 1.4 GHz, S-193 RADSCAT (Radiometer-Scatterometer) operating at 13.9 GHz, and the Nimbus 5

Fawwaz T. Ulaby; Louis F. Dellwig; Thomas Schmugge

1975-01-01

333

Simultaneous Measurements of Atmospheric Emissions at 10, 33 and 90 GHz.  

National Technical Information Service (NTIS)

As part of a larger experiment to measure the cosmic microwave background radiation spectrum, frequent simultaneous measurements of the microwave thermal emission from the earth's atmosphere were made at three fixed frequencies, namely, 10 GHz, 33 GHz and...

J. B. Costales

1984-01-01

334

Satellite microwave radiances correlated with radar rain rates over land  

NASA Astrophysics Data System (ADS)

Satellite methods for the measurement of precipitation have used images obtained at visible, IR and microwave frequencies. Visible/IR methods infer precipitation from the appearance and behaviour of clouds. Microwave methods are more direct because the microwave radiation upwelling from the Earth is affected more by rain drops than by cloud droplets. These radiances viewed by a sensor outside the atmosphere are presented here as brightness temperature, the product of the thermodynamic temperature and emissivity of the surface viewed, modified by the intervening atmospheric constituents (water droplets, water vapour, gaseous absorption, and so on).

Spencer, R. W.; Martin, D. W.; Hinton, B. B.; Weinman, J. A.

1983-07-01

335

Dinotor model for anomalous nuclei  

SciTech Connect

The simplest version of the MIT bag model implies the existence of metastable toroidal bags, with large radius proportional to the enclosed baryon number, and small radius comparable to that of an ordinary nucleon (we refer to those toroidal bags as dinotors). Considerations of various possible instabilities, and of the effects of quark interactions through intermediate gluons, suggest that the metastability is still valid when the model is treated more realistically. These results might provide an explanation for reports of anomalously large interaction cross sections of secondary fragments (''anomalons'') observed in visual track detectors. However, it appears that the most likely characteristics of toroidal bags would not be compatible with those of anomalons, and would not be as easy to detect in emulsions. copyright 1986 Academic Press, Inc.

Castillejo, L.; Goldhaber, A.S.; Jackson, A.D.; Johnson, M.B.

1986-12-01

336

Variable frequency microwave heating apparatus  

SciTech Connect

A variable frequency microwave heating apparatus (10) designed to allow modulation of the frequency of the microwaves introduced into a multi-mode microwave cavity (34) for testing or other selected applications. The variable frequency microwave heating apparatus (10) includes a microwave signal generator (12) and a high-power microwave amplifier (20) or a high-power microwave oscillator (14). A power supply (22) is provided for operation of the high-power microwave oscillator (14) or microwave amplifier (20). A directional coupler (24) is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity (34). A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Bible, D.W.; Lauf, R.J.; Johnson, A.C.; Thigpen, L.T.

1999-10-05

337

Observation of Anomalous Ion Heating by Broadband Drift-Wave Turbulence  

SciTech Connect

Using laser induced fluorescence and passive spectroscopy on a magnetically confined low-temperature plasma, anomalous ion heating is observed which exceeds collisional heating from the electrons by a factor of up to five. Direct wave heating due to the 2.45 GHz microwave as well as stochastic heating by large-amplitude fluctuations could be ruled out as explanations. Good quantitative agreement is found when comparing the missing power in the ion species with heating power due to the dissipation of drift-wave turbulence. This turbulent energy transfer into the ion channel could have important consequences for the interpretation of transport in fusion plasmas.

Enge, S.; Birkenmeier, G.; Manz, P.; Ramisch, M.; Stroth, U. [Institut fuer Plasmaforschung, Universitaet Stuttgart, 70569 Stuttgart (Germany)

2010-10-22

338

Observation of anomalous ion heating by broadband drift-wave turbulence.  

PubMed

Using laser induced fluorescence and passive spectroscopy on a magnetically confined low-temperature plasma, anomalous ion heating is observed which exceeds collisional heating from the electrons by a factor of up to five. Direct wave heating due to the 2.45 GHz microwave as well as stochastic heating by large-amplitude fluctuations could be ruled out as explanations. Good quantitative agreement is found when comparing the missing power in the ion species with heating power due to the dissipation of drift-wave turbulence. This turbulent energy transfer into the ion channel could have important consequences for the interpretation of transport in fusion plasmas. PMID:21231054

Enge, S; Birkenmeier, G; Manz, P; Ramisch, M; Stroth, U

2010-10-21

339

Optical emission spectrometric determination of arsenic and antimony by continuous flow chemical hydride generation and a miniaturized microwave microstrip argon plasma operated inside a capillary channel in a sapphire wafer  

NASA Astrophysics Data System (ADS)

Continuous flow chemical hydride generation coupled directly to a 40 W, atmospheric pressure, 2.45 GHz microwave microstrip Ar plasma operated inside a capillary channel in a sapphire wafer has been optimized for the emission spectrometric determination of As and Sb. The effect of the NaBH4 concentration, the concentration of HCl, HNO3 and H2SO4 used for sample acidification, the Ar flow rate, the reagent flow rates, the liquid volume in the separator as well as the presence of interfering metals such as Fe, Cu, Ni, Co, Zn, Cd, Mn, Pb and Cr, was investigated in detail. A considerable influence of Fe(III) (enhancement of up to 50 %) for As(V) and of Fe(III), Cu(II) and Cr(III) (suppression of up to 75%) as well as of Cd(II) and Mn(II) (suppression by up to 25%) for Sb(III) was found to occur, which did not change by more than a factor of 2 in the concentration range of 2 20 ?g ml- 1. The microstrip plasma tolerated the introduction of 4.2 ml min- 1 of H2 in the Ar working gas, which corresponded to an H2/Ar ratio of 28%. Under these conditions, the excitation temperature as measured with Ar atom lines and the electron number density as determined from the Stark broadening of the H? line was of the order of 5500 K and 1.50 · 1014 cm- 3, respectively. Detection limits (3?) of 18 ng ml- 1 for As and 31 ng ml- 1 for Sb were found and the calibration curves were linear over 2 orders of magnitude. With the procedure developed As and Sb could be determined at the 45 and 6.4 ?g ml- 1 level in a galvanic bath solution containing 2.5% of NiSO4. Additionally, As was determined in a coal fly ash reference material (NIST SRM 1633a) with a certified concentration of As of 145 ± 15 ?g g- 1 and a value of 144 ± 4 ?g g- 1 was found.

Pohl, Pawel; Zapata, Israel Jimenéz; Bings, Nicolas H.; Voges, Edgar; Broekaert, José A. C.

2007-05-01

340

Milestones of microwaves  

Microsoft Academic Search

This paper presents a compilation of the important milestones in the development and applications of microwave technology from the time of Hertz until 1980. The years from 1980 to the present are not addressed since this period will be covered in depth in other papers of this Transactions. The primary technology areas addressed are electromagnetics, guided microwave structures, free-space propagation,

Harold Sobol; Kiyo Tomiyasu

2002-01-01

341

Modelling microwave heating  

Microsoft Academic Search

Although microwave radiation is best known for heating food in the kitchen, in recent years it has found new applications in many industrial processes, such as those involving melting, smelting, sintering, drying, and joining. Heating by microwave radiation constitutes a highly coupled nonlinear problem giving rise to new and unexpected physical behavior, the best known of which is the appearance

James M Hill; Timothy R Marchant

1996-01-01

342

MICROWAVES IN ORGANIC SYNTHESIS  

EPA Science Inventory

The effect of microwaves, a non-ionizing radiation, on organic reactions is described both in polar solvents and under solvent-free conditions. The special applications are highlighted in the context of solventless organic synthesis which involve microwave (MW) exposure of neat r...

343

The Microwave-Drill  

Microsoft Academic Search

Summary form only given, as follows. The microwave drill is a novel method to cut and drill into hard non-conductive materials by localized microwave energy. The method has been tested on various materials, including concrete, glass, silicon, ceramics, and ceramic coatings. It yields holes in diameters from 0.3 mm to > 10 mm (in concrete). A theoretical model simulates the

E. Jerby; V. Dikhtyar; O. Aktushev; U. Grosglick

2002-01-01

344

Polypyrrole Based Microwave Absorbers  

Microsoft Academic Search

Reflection of microwave radiations from single layer and two-layer materials is calculated. Microwave absorbing materials are formulated by mixing a commercially available paint or rubber with the conducting polypyrrole (PPy) powder. The reflection loss strongly depends on thickness and complex permittivity of the material. For a single layer material, optimum values of the real part, ?', and imaginary part, ?'',

V.-T. Truong; S. Z. Riddell; R. F. Muscat

1998-01-01

345

Microwave processing of ceramics  

SciTech Connect

Recent work in the areas of microwave processing and joining of ceramics is briefly reviewed. Advantages and disadvantages of microwave processing as well as some of the current issues in the field are discussed. Current state and potential for future commercialization of this technology is also addressed.

Katz, J.D.

1993-04-01

346

Microwave processing of ceramics  

SciTech Connect

Recent work in the areas of microwave processing and joining of ceramics is briefly reviewed. Advantages and disadvantages of microwave processing as well as some of the current issues in the field are discussed. Current state and potential for future commercialization of this technology is also addressed.

Katz, J.D.

1993-01-01

347

Ultrastable Cryogenic Microwave Oscillators  

Microsoft Academic Search

Ultrastable cryogenic microwave oscillators are secondary frequency standards in the microwave domain. The best of these oscillators have demonstrated a short term frequency stability in the range 10-14 to a few times 10-16. The main application for these oscillators is as flywheel oscillators for the next generation of passive atomic frequency standards, and as local oscillators in space telemetry ground

Anthony G. Mann

2001-01-01

348

Microwave plasma assisted sputtering  

Microsoft Academic Search

Indium tin oxide (ITO) films were prepared on SiO2 and on resin coated glass by microwave assisted sputtering and by magnetron dc sputtering using ITO targets. To find out the advantages of the microwave assisted sputtering in comparison to the magnetron sputtering the results of the two methods are compared. At substrate temperatures of 200°C ITO films with a specific

R. Latz; C. Daube; T. Haranou; B. Ocker; K. Suzuki

1997-01-01

349

Microwave welding of thermoplastics  

Microsoft Academic Search

The aim of this work was to develop a new and versatile method for welding thermoplastics using microwave energy. A multimode cavity applicator was developed including features designed to deliver an even energy density and to apply weld pressure. A review of possible microwave susceptible implant materials was undertaken and results of welding trials using several candidate materials showed that

R. J. Wise; I. D. Froment

2001-01-01

350

Microwave Applications to Transportation  

Microsoft Academic Search

In view of the fact that microwaves first impacted our technology during or slightly before World War II, it is natural that the greatest number of microwave applications have been directed to the solution of military problems. Very advanced techniques have been developed and form the basis of many of our modern weapon systems. Development costs have been astronomical but

L. W. Roberts

1971-01-01

351

Diagnostics of Microwave Bubble Plasma in Liquid  

NASA Astrophysics Data System (ADS)

Plasma production in the liquid phase has attracted much attention due to its potential applications such as biomedical or environmental processes. As a new technique, we have developed bubble plasma production in liquid with use of pulsed microwave from a slot antenna, and have succeeded in decomposing harmful chemicals such as trichloroethylene (TCE). In this work, optical emission and absorption spectroscopies were adopted to diagnose the microwave bubble plasma. OES result indicated strong OH emission from the plasma, suggesting production of reactive OH radical in the bubble plasma from water vapor. Furthermore, plasma density of the bubble plasma was investigated by time-resolved Stark broadening spectroscopy. To give insight into the reactive species in the liquid phase, plasma-treated water was investigated with UV/VIS optical absorption spectroscopy and a chemical reagent that is sensitive to hydrogen peroxide. From these measurements, existence of hydrogen peroxide in the liquid phase was confirmed.

Toyoda, Hirotaka; Sugiura, Hiroyasu; Saito, Ryota; Ishijima, Tatsuo

2008-10-01

352

First results from the microwave air yield beam experiment (MAYBE): Measurement of GHz radiation for ultra-high energy cosmic ray detection  

NASA Astrophysics Data System (ADS)

We present measurements of microwave emission from an electron-beam induced air plasma performed at the 3 MeV electron Van de Graaff facility of the Argonne National Laboratory. Results include the emission spectrum between 1 and 15 GHz, the polarization of the microwave radiation and the scaling of the emitted power with respect to beam intensity. MAYBE measurements provide further insight on microwave emission from extensive air showers as a novel detection technique for Ultra-High Energy Cosmic Rays.

Williams, C.; Bohá?ová, M.; Bonifazi, C.; Cataldi, G.; Chemerisov, S.; de Mello Neto, J. R. T.; Facal San Luis, P.; Fox, B.; Gorham, P. W.; Hojvat, C.; Hollon, N.; Meyhandan, R.; Monasor, M.; Rouillé d'Orfeuil, B.; Santos, E. M.; Pochez, J.; Privitera, P.; Spinka, H.; Verzi, V.; Zhou, J.

2013-06-01

353

Parallel Telescope Observations of Anomalous Refraction  

NASA Astrophysics Data System (ADS)

We present the results of an observing campaign at the US Naval Observatory, Flagstaff Station examining the relationship between anomalous refraction and coherent motions in the atmosphere. Anomalous refraction is a quasi-periodic error in astrometric positions with characteristic timescales of minutes to tens of minutes and amplitudes of up to several tenths of an arcsecond. Three dissimilar telescopes observed the same star field in drift-scan mode in tandem with a suite of atmospheric instrumentation for nine nights in 2008. All resulting astrometric data, when referenced against standard catalogs, such as UCAC2 or the Carlsberg Meridian Catalog, consistently exhibits residuals typical of anomalous refraction as described by previously published accounts. Comparing residuals from astrometric data taken simultaneously on multiple telescopes indicates whether the observed anomalous refraction is due to atmospheric effects that are coherent over spatial scales corresponding to the telescope separation (e.g. atmospheric gravity waves), or more localized sources (e.g. telescope motion, dome seeing). Atmospheric observations (wind, surface pressure, temperature, etc.) provide additional information on which conditions may be related to the occurrence of anomalous refraction and allow correlation of specific astrometric error timescales and events with certain atmospheric or weather conditions. This research constitutes the first detailed study of anomalous refraction employing multiple telescopes, weather instrumentation and instruments specifically designed to observe large-scale coherent atmospheric motions. As such these results provide valuable new insight into the phenomenon of anomalous refraction.

Taylor, Suzanne; McGraw, J.; Zimmer, P.; Pier, J.

2009-01-01

354

Radiofrequency and microwave radiation  

SciTech Connect

This paper deals with the controversy and disagreement surrounding the issue of harm from radiofrequency (RF) and microwaves. The radiation standards adopted by different countries are quite divergent with the least strict standard for microwave exposure differing from the most strict by a factor of 100. Among the most powerful sources of RF and microwave radiation are radar systems used for tracking and guidance purposes, as well as transmiters used in satellite communication systems. RF and microwaves are nonionizing because the energy of each photon is relatively low. Biological systems exposed to RF and microwaves acquire induced electric and magnetic fields which can be focused by a combination of high refractive index within an animal and convex body contours. The effects on animals and humans are summarized. (KRM)

Hileman, B.

1982-08-01

355

Gigawatt-level microwave bursts from a new type of virtual cathode oscillator  

SciTech Connect

We describe experiments that demonstrate a new method for producing high-power microwave emission. The unstable oscillations of a virtual cathode which forms when a magnetized relativistic electron beam is injected into a circular waveguide generate the microwave radiation. In contrast to previous virtual cathode microwave generation techniques, electrons in the waveguide cannot be reflected back into the diode. Using this technique, we have produced 1.4 GW at 3.9 GHz with several hundred megawatts radiated in harmonic radiation.

Davis, H.A.; Bartsch, R.R.; Kwan, T.J.T.; Sherwood, E.G.; Stringfield, R.M.

1987-07-20

356

Photonic technology for microwave engineering  

Microsoft Academic Search

The paper presents a review of photonic devices and technology applications in microwave systems. Four fundamental applications are discussed: transmission of microwave signals by optical links, use of photonic devices for generation and controlling of microwave signals, principles of operation of phase-arrayed antennas with photonic transmission, and finally, microwave measurements methods with photonic techniques

BOGDAN A. GALWAS

1998-01-01

357

The small scale power asymmetry in the cosmic microwave background  

NASA Astrophysics Data System (ADS)

We investigate the hemispherical power asymmetry in the cosmic microwave background on small angular scales. We find an anomalously high asymmetry in the multipole range l = 601?2048, with a naive statistical significance of 6.5?. However, we show that this extreme anomaly is simply a coincidence of three other effects, relativistic power modulation, edge effects from the mask applied, and inter-scale correlations. After correcting for all of these effects, the significance level drops to ~ 1?, i.e., there is no anomalous intrinsic asymmetry in the small angular scales. Using this null result, we derive a constraint on a potential dipolar modulation amplitude, A(k) < 0.0045 on the ~ 10 Mpc-scale, at 95% C.L. This new constraint must be satisfied by any theoretical model attempting to explain the hemispherical asymmetry at large angular scales.

Flender, Samuel; Hotchkiss, Shaun

2013-09-01

358

The microwave frequency method  

NASA Astrophysics Data System (ADS)

We present new results showing that when sufficient microwave power is employed the grains carrying the natural remanent moment (NRM) that are able to absorb microwaves reach their blocking temperature in less than 10 ms, and the sample temperature at the end of this very short time has only increased by about 30 °C. We also show that because large gaps exist in the spin-wave frequency of small particles, some grains are unable to absorb because they are too small, and others because they are too large. A large number of results have been published, that were obtained using frequencies close to 14 GHz, using what has been called the microwave Thellier method. However, as Biggin has pointed out [Biggin, A.J., et al., 2007. A comparison of a quasi-perpendicular method of absolute palaeointensity determination with other thermal and microwave techniques. Earth Planet. Sci. Lett. 257, 564-581] the microwaves constitute a marginal improvement on thermal methods, with the attendant alteration problems. We wish to propose a radically new method here, the microwave frequency method, where the microwave frequency is varied, selectively magnetizing and demagnetizing grains of different sizes thereby keeping the sample temperature so low that alteration is avoided completely.

Walton, Derek; Boehnel, Harald N.

2008-04-01

359

Microwave photonic signal processing.  

PubMed

Photonic signal processing offers the advantages of large time-bandwidth capabilities to overcome inherent electronic limitations. In-fibre signal processors are inherently compatible with fibre optic microwave systems that can integrate with wireless antennas, and can provide connectivity with in-built signal conditioning and electromagnetic interference immunity. Recent methods in wideband and adaptive signal processing, which address the challenge of realising programmable microwave photonic phase shifters and true-time delay elements for phased array beamforming; ultra-wideband Hilbert transformers; single passband, widely tunable, and switchable microwave photonic filters; and ultra-wideband microwave photonic mixers, are described. In addition, a new microwave photonic mixer structure is presented, which is based on using the inherent frequency selectivity of the stimulated Brillouin scattering loss spectrum to suppress the carrier of a dual-phase modulated optical signal. Results for the new microwave photonic mixer demonstrate an extremely wide bandwidth operation of 0.2 to 20 GHz and a large conversion efficiency improvement compared to the conventional microwave photonic mixer. PMID:24104178

Minasian, R A; Chan, E H W; Yi, X

2013-09-23

360

Generalized dispersive wave emission in nonlinear fiber optics.  

PubMed

We show that the emission of dispersive waves in nonlinear fiber optics is not limited to soliton-like pulses propagating in the anomalous dispersion regime. We demonstrate, both numerically and experimentally, that pulses propagating in the normal dispersion regime can excite resonant dispersive radiation across the zero-dispersion wavelength into the anomalous regime. PMID:23454945

Webb, K E; Xu, Y Q; Erkintalo, M; Murdoch, S G

2013-01-15

361

Enhancing phosphorylation cascades by anomalous diffusion  

NASA Astrophysics Data System (ADS)

A key event in many cellular signaling cascades is the multiple phosphorylation of proteins by specialized kinases. A prototypical example is the mitogen-activated protein kinase (MAPK) that alters the cell's gene transcription after having been phosphorylated twice by the same kinase. Here, we show that anomalous diffusion, induced, for example, by cytoplasmic crowding, can significantly improve the activation of MAPK. Our results on anomalous diffusion with the characteristics of fractional Brownian motion and obstructed diffusion compare favorably to very recent biochemical data on MAPK activation at varying degrees of cytoplasmic crowding. Our results predict any Michaelis-Menten scheme in which a substrate is modified by the same enzyme several times to show an increased performance due to anomalous diffusion when dissociation rates of the intermediate enzyme-substrate complexes are high while the irreversible catalytic step is slow. Thus, crowding-induced anomalous diffusion can strongly alter the behavior of many cellular signaling pathways.

Hellmann, M.; Heermann, D. W.; Weiss, M.

2012-03-01

362

Anomalous Scaling of the Passive Scalar.  

National Technical Information Service (NTIS)

The authors establish anomalous inertial range scaling of the structure functions for a model of homogeneous, isotropic advection of a passive scalar by a random velocity field. The velocity statistics is taken gaussian with decorrelation in time and velo...

K. Gawedzki A. Kupiainen

1995-01-01

363

Anomalous mitral arcade: Echocardiographic and angiographic recognition  

Microsoft Academic Search

Summary A patient with sudden onset of hemiplegia was noted to have an anomalous mitral arcade at cardiac surgery. Echocardiographic and angiographic data are correlated with the anatomic findings. The clinical significance of this anomaly is discussed.

Grant V. S. Parr; Raymond R. Fripp; Victor Whitman; Saroja Bharati; Maurice Lev

1983-01-01

364

Anomalous Photon-Assisted Tunneling in Graphene.  

National Technical Information Service (NTIS)

We investigated the transmission of Dirac electrons through a potential barrier in the presence of circularly polarized light. An anomalous photon-assisted enhanced transmission is predicted and explained. It is demonstrated that the perfect transmission ...

A. Iurov D. Huang G. Gumbs O. Roslyak

2012-01-01

365

Excited-State Perylene-Pyrene Interactions: Relation to the Interpretation of Excimer Emission.  

National Technical Information Service (NTIS)

The 'anomalous' emission properties of perylene-pyrene mixed crystals were re-examined. The results of this study demonstrate that the unusual character of the mixed-crystal emission spectra is primarily due to reabsorption of 'normal' monomeric perylene ...

K. Kawaoka D. R. Kearns

1964-01-01

366

Modelling anomalous extinction using nanodiamonds  

NASA Astrophysics Data System (ADS)

The modelling of extinction along anomalous/non-Cardelli, Clayton & Mathis sightlines, which are characterized by a broad 217.5-nm bump and steep far-ultraviolet (FUV) rise, is reported. The extinction along these sightlines, namely HD 210121, HD 204827, HD 29647 and HD 62542, is difficult to reproduce using standard silicate and graphite grains. A very good match with the observed extinction is obtained by considering a nanodiamond component as part of the carbonaceous matter. Most of these sightlines are rich in carbon and are invariably backed by a young hot stellar object. Nanodiamond is taken as a core within amorphous carbon and graphite. These core-mantle particles, taken as additional components along with graphite and silicates, lead to a reduction in the silicate requirement. The abundance of carbonaceous matter is not affected, as a very small fraction of nanodiamond is required. Extinction along sightlines that show steep FUV is also reported, demonstrating the importance of the nanodiamond component in all such regions.

Rai, Rakesh K.; Rastogi, Shantanu

2012-07-01

367

Anomalous dynamics of polymer translocation  

NASA Astrophysics Data System (ADS)

We study the passage times of a translocating polymer of length N in three dimensions, while it passes through a narrow pore. We show that the behavior of the polymer stems from the polymer dynamics at the immediate vicinity of the pore --- in particular, the memory effects in the polymer chain tension imbalance across the pore. We take as a reaction coordinate the number s of the monomer residing in the pore. in the case of unbiased translocation, these memory effects cause the mobility of s to be anomalous diffusion for times up to the Rouse time N˜N^1+2? or Zimm time N˜N^3?, without or with hydrodynamics, respectively. Here, ? is the Flory exponent. Beyond this time, the dynamics becomes ordinary diffusion. As a consequence, the pore blockade time scales with length as ?d˜N^2+?. If a force of sufficient strength is pulling on one end, the pore blockade time scales as ?d˜N^2 in the absence of hydrodynamics. If a voltage is applied across the pore, which drives the charged polymer, the pore blockade time scales as ?d˜N^(1+2?)/(1+?) without, and ?d˜N^3?/(1+?) with hydrodynamics. In these cases, the pore blockade time decreases inversely with force and field strength, respectively. Our theoretical framework is substantiated with high-precision computer simulations. We will show that memory effects similar to those governing translocation, also play a role in the dynamics of dense polymer solutions and polymer melts.

Barkema, Gerard

2009-03-01

368

Anomalous dynamics of cell migration  

PubMed Central

Cell movement—for example, during embryogenesis or tumor metastasis—is a complex dynamical process resulting from an intricate interplay of multiple components of the cellular migration machinery. At first sight, the paths of migrating cells resemble those of thermally driven Brownian particles. However, cell migration is an active biological process putting a characterization in terms of normal Brownian motion into question. By analyzing the trajectories of wild-type and mutated epithelial (transformed Madin–Darby canine kidney) cells, we show experimentally that anomalous dynamics characterizes cell migration. A superdiffusive increase of the mean squared displacement, non-Gaussian spatial probability distributions, and power-law decays of the velocity autocorrelations is the basis for this interpretation. Almost all results can be explained with a fractional Klein–Kramers equation allowing the quantitative classification of cell migration by a few parameters. Thereby, it discloses the influence and relative importance of individual components of the cellular migration apparatus to the behavior of the cell as a whole.

Dieterich, Peter; Klages, Rainer; Preuss, Roland; Schwab, Albrecht

2008-01-01

369

Anomalous axial propagation in helicoidal bianisotropic media  

NASA Astrophysics Data System (ADS)

Anomalous axial propagation, characterized by axially propagating Voigt waves, in a general linear helicoidal bianisotropic medium (HBM) is examined. A fourth-order ordinary differential equation is derived, from which the conditions for anomalous axial propagation emerge. The analysis is exemplified by application to supercholesteric media, which include cholesteric liquid crystals. In addition, purely dielectric HBMs are considered in detail, with later specialization to chiral smectic dielectric media, and light is shed on the effects of reciprocity and dissipation.

Lakhtakia, Akhlesh

1998-12-01

370

Evaluation of Multi-Frequency-Microwave-Radiometer-System performance for oceanography  

Microsoft Academic Search

A technique is presented for constructing a mathematical model of a Multi-Frequency Microwave Radiometer System. The technique combines the different responses of microwave radiometers with models of the sea surface, the effects of the Earth's atmosphere and of the sky emission. A linear perturbation method and a more accurate non-linear method are outlined for processing of data simultaneously collected by

Lars Thrane; Electromagnetics Institurute

1978-01-01

371

Sensitivity to microwave measurements to vegetation biomass and soil moisture content: a case study  

Microsoft Academic Search

A comparative evaluation of the potential of active and passive microwave sensors in estimating vegetation biomass and soil moisture content is carried out. For this purpose, experimental data collected on an agricultural area by airborne scatterometers and radiometers during the AGRISCATT and AGRIRAD 1988 campaigns have been used. The results show that both microwave backscattering and emission are sensitive to

Paolo Ferrazzoli; Simonetta Paloscia; Paolo Pampaloni; Giovanni Schiavon; Domenico Solimini; Peter Coppo

1992-01-01

372

Retrieval of atmospheric and surface parameters from satellite microwave radiometers over the Mediterranean Sea  

Microsoft Academic Search

A procedure to estimate atmospheric and sea surface parameters in the Mediterranean area from satellite microwave radiometric measurements is described. The method is founded on a simulator of brightness temperatures at the top of the atmosphere. The simulator is based on microwave sea emissivity and scattering model functions, derived from the outputs of the SEAWIND software, which implements a two-scale

Luca Pulvirenti; Nazzareno Pierdicca

2006-01-01

373

Microwave–hydrothermal synthesis of fluorescent carbon dots from graphite oxide  

Microsoft Academic Search

Graphite oxide (GO), candle soot, conductive carbon black and lampblack were used to prepare fluorescent carbon dots (CDots) by heating under reflux in nitric acid. The CDots prepared from GO exhibited the highest quantum yield and narrowest emission of those produced. Microwave-assisted techniques were also used to synthesize CDots. Compared with conventional heating under reflux, microwave-assisted heating under reflux and

Qinlong Wang; Huzhi Zheng; Yijuan Long; Lingyan Zhang; Mei Gao; Wenjun Bai

2011-01-01

374

Reduction of weather effects in the calculation of sea ice concentration from microwave radiances  

Microsoft Academic Search

A technique is presented which improves existing methods of calculating sea ice concentrations from microwave radiances by reducing weather-related effects over open ocean areas and in the vicinity of marginal sea ice zones. Winds, atmospheric water vapor, cloud liquid water, and rain increase the microwave emission over these regions and thus result in erroneous values of computed sea ice concentration.

P. Gloersen; D. J. Cavalieri

1986-01-01

375

Using a modeling approach to predict soil hydraulic properties from passive microwave measurements  

Microsoft Academic Search

A soil water and energy budget model coupled with a microwave emission model (MICRO-SWEAT) was used to predict the diurnal courses of soil surface water content and microwave brightness temperatures during a number of drying cycles on soils of contrasting texture that were either cropped or bare. The parameters describing the soil water retention and conductivity characteristics [saturated hydraulic conductivity,

E. J. Burke; R. J. Gurney; L. P. Simmonds; P. E. O'Neill

1998-01-01

376

Microwave coupler and method  

DOEpatents

The present invention is directed to a microwave coupler for enhancing the heating or metallurgical treatment of materials within a cold-wall, rapidly heated cavity as provided by a microwave furnace. The coupling material of the present invention is an alpha-rhombohedral-boron-derivative-structure material such as boron carbide or boron silicide which can be appropriately positioned as a susceptor within the furnace to heat other material or be in powder particulate form so that composites and structures of boron carbide such as cutting tools, grinding wheels and the like can be rapidly and efficiently formed within microwave furnaces.

Holcombe, Cressie E. (Farragut, TN)

1985-01-01

377

Superconducting microwave transmission lines  

SciTech Connect

Superconducting microwave transmission lines can be designed to have lower loss, lower dispersion, and lower phase velocity than conventional metal lines. These properties make superconducting transmission lines attractive for use in many devices and systems such as filters and analog to digital converters. The problem with designing microwave circuits which utilizes these lines is that accurate circuit models do not exist. This paper present models for the microwave transmission line parameters (phase velocity, attenuation, and characteristic impedance) of superconducting lines as a function of temperature and geometry. An experiment to verify these models is also presented.

McClay, C.P.; Soares, S.; Weitzman, P.S.

1991-10-01

378

Correlating anomalies of the microwave sky  

SciTech Connect

At the largest angular scales the presence of a number of unexpected features has been confirmed by the latest measurements of the cosmic microwave background (CMB). Among them are the anomalous alignment of the quadrupole and octopole with each other as well as the stubborn lack of angular correlation on scales >60 deg. We search for correlations between these two phenomena and demonstrate their absence. A Monte Carlo likelihood analysis confirms previous studies and shows that the joint likelihood of both anomalies is incompatible with the best-fit {lambda} cold dark matter model at >99.95% C.L. Extending also to higher multipoles, a common special direction (the 'Axis of Evil') has been identified. In the search for an explanation of the anomalies, several studies invoke effects that exhibit an axial symmetry. We find that this interpretation of the 'Axis of Evil' is inconsistent with three-year data from the Wilkinson Microwave Anisotropy Probe (WMAP). The data require a preferred plane, whereupon the axis is just the normal direction. Rotational symmetry within that plane is ruled out at high confidence.

Rakic, Aleksandar; Schwarz, Dominik J. [Fakultaet fuer Physik, Universitaet Bielefeld, Postfach 100131, D-33501 Bielefeld (Germany)

2007-05-15

379

Emissivity corrected infrared method for imaging anomalous structural heat flows  

DOEpatents

A method for detecting flaws in structures using dual band infrared radiation is disclosed. Heat is applied to the structure being evaluated. The structure is scanned for two different wavelengths and data obtained in the form of images. Images are used to remove clutter to form a corrected image. The existence and nature of a flaw is determined by investigating a variety of features. 1 fig.

Del Grande, N.K.; Durbin, P.F.; Dolan, K.W.; Perkins, D.E.

1995-08-22

380

Emissivity corrected infrared method for imaging anomalous structural heat flows  

DOEpatents

A method for detecting flaws in structures using dual band infrared radiation. Heat is applied to the structure being evaluated. The structure is scanned for two different wavelengths and data obtained in the form of images. Images are used to remove clutter to form a corrected image. The existence and nature of a flaw is determined by investigating a variety of features.

Del Grande, Nancy K. (San Leandro, CA); Durbin, Philip F. (Livermore, CA); Dolan, Kenneth W. (Livermore, CA); Perkins, Dwight E. (Livermore, CA)

1995-01-01

381

Simple Microwave Resonance Spectrometer  

Microsoft Academic Search

A relatively simple and inexpensive apparatus for the observation of electron paramagnetic resonance at microwave frequencies is described. The apparatus is designed for the undergraduate laboratory but, with some modification, may be used as a research tool.

E. S. Gravlin; J. A. Cowen

1959-01-01

382

Microwave Tokamak Experiment (MTX).  

National Technical Information Service (NTIS)

A new experimental facility is being assembled at the Lawrence Livermore National Laboratory (LLNL) for studying microwave propagation and absorption in high density plasmas. A unique feature of the facility is the free electron laser (FEL) used to genera...

K. I. Thomassen B. I. Cohen E. B. Hooper D. D. Lang W. M. Nevins

1987-01-01

383

Microwave Oven Observations.  

ERIC Educational Resources Information Center

|Explains a series of laboratory activities which employ a microwave oven to help students understand word problems that relate to states of matter, collect data, and calculate and compare electrical costs to heat energy costs. (DDR)|

Sumrall, William J.; Richardson, Denise; Yan, Yuan

1998-01-01

384

Industrial microwave sensors  

Microsoft Academic Search

Surveys the different types of microwave sensors and reviews the latest developments reported by European institutes and companies. Attention is given to resonator, transmission, reflection, radar, and radiometer sensors, and to active imaging

Ebbe Nyfors; Pertti Vainikainen

1991-01-01

385

The microwave drill.  

PubMed

We present a drilling method that is based on the phenomenon of local hot spot generation by near-field microwave radiation. The microwave drill is implemented by a coaxial near-field radiator fed by a conventional microwave source. The near-field radiator induces the microwave energy into a small volume in the drilled material under its surface, and a hot spot evolves in a rapid thermal-runaway process. The center electrode of the coaxial radiator itself is then inserted into the softened material to form the hole. The method is applicable for drilling a variety of nonconductive materials. It does not require fast rotating parts, and its operation makes no dust or noise. PMID:12386331

Jerby, E; Dikhtyar, V; Aktushev, O; Grosglick, U

2002-10-18

386

Superconducting Microwave Transmission Lines.  

National Technical Information Service (NTIS)

Superconducting microwave transmission lines can be designed to have lower loss, lower dispersion, and lower phase velocity than conventional metal lines. These properties make superconducting transmission lines attractive for use in many devices and syst...

C. P. McClay P. S. Weitzman S. Soares

1991-01-01

387

Microwave Oven Observations.  

ERIC Educational Resources Information Center

Explains a series of laboratory activities which employ a microwave oven to help students understand word problems that relate to states of matter, collect data, and calculate and compare electrical costs to heat energy costs. (DDR)

Sumrall, William J.; Richardson, Denise; Yan, Yuan

1998-01-01

388

Microwave fluid flow meter  

DOEpatents

A microwave fluid flow meter is described utilizing two spaced microwave sensors positioned along a fluid flow path. Each sensor includes a microwave cavity having a frequency of resonance dependent upon the static pressure of the fluid at the sensor locations. The resonant response of each cavity with respect to a variation in pressure of the monitored fluid is represented by a corresponding electrical output which can be calibrated into a direct pressure reading. The pressure drop between sensor locations is then correlated as a measure of fluid velocity. In the preferred embodiment the individual sensor cavities are strategically positioned outside the path of fluid flow and are designed to resonate in two distinct frequency modes yielding a measure of temperature as well as pressure. The temperature response can then be used in correcting for pressure responses of the microwave cavity encountered due to temperature fluctuations.

Billeter, Thomas R. (Richland, WA); Philipp, Lee D. (Richland, WA); Schemmel, Richard R. (Lynchburg, VA)

1976-01-01

389

Microwave Switching Circuits.  

National Technical Information Service (NTIS)

The monograph is concerned with the design, exploitation, and operation of microwave antennas and equipment. It presents in monographic form a number of the most fundamental and frequently used groups of switching systems.

A. Kraszewski

1969-01-01

390

IDENTIFYING THE RADIO BUBBLE NATURE OF THE MICROWAVE HAZE  

SciTech Connect

Using seven-year data from the Wilkinson Microwave Anisotropy Probe, I identify a sharp 'edge' in the microwave haze at high southern Galactic latitude (-55 Degree-Sign < b < -35 Degree-Sign ) that is spatially coincident with the southern edge of the 'Fermi haze/bubbles'. This finding proves conclusively that the edge in the gamma rays is real (and not a processing artifact), demonstrates explicitly that the microwave haze and the gamma-ray bubbles are indeed the same structure observed at multiple wavelengths, and strongly supports the interpretation of the microwave haze as a separate component of Galactic synchrotron (likely generated by a transient event) as opposed to a simple variation of the spectral index of disk synchrotron. In addition, combining these data sets allows for the first determination of the magnetic field within a radio bubble using microwaves and gamma rays by taking advantage of the fact that the inverse Compton gamma rays are primarily generated by scattering of cosmic microwave background photons at these latitudes, thus minimizing uncertainty in the target radiation field. Assuming uniform volume emissivity, I find that the magnetic field within the southern Galactic microwave/gamma-ray bubble is {approx}5 {mu}G above 6 kpc off of the Galactic plane.

Dobler, Gregory, E-mail: dobler@kitp.ucsb.edu [Kavli Institute for Theoretical Physics, University of California, Santa Barbara Kohn Hall, Santa Barbara, CA 93106 (United States)

2012-11-20

391

Properties of microwave plasma torch operating at a low pressure  

SciTech Connect

A microwave plasma torch system is attached to a low-pressure chamber in this study. The electric field induced in a quartz discharge tube by microwave radiation breaks down the gas at a sufficiently low pressure, igniting the plasma, which is continuously sustained by the microwave radiation. The plasma profile at a very low pressure is shown to be asymmetric with higher density on the incoming side of the microwaves. The gas temperature at the bright spot of the torch plasma measured via the optical emission from hydroxide radicals is shown to increase drastically upon high-pressure operation as the microwave power increases. The electron density at the torch flame is measured by recording the Stark broadening of the hydrogen Balmer beta line. The plasma density increases as the microwave power increases. The typical argon plasma density of a plasma torch powered at 500 W under a pressure of 150 Torr is on the order of 10{sup 14}/cm{sup 3}. The electron temperature in the argon torch plasma was estimated to be 1.5 eV, thereby effectively exciting the molecules in the torch gas. Disintegration of nitrogen fluoride (NF{sub 3}) indicates that a microwave plasma torch operating at a low pressure can efficiently generate an abundant amount of chemical radicals.

Cho, Soon C.; Uhm, Han S.; Hong, Yong C.; Kim, Jae H. [Department of Molecular Science and Technology, Ajou University, San 5 Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of)

2008-10-15

392

Ultrastable Cryogenic Microwave Oscillators  

Microsoft Academic Search

Ultrastable cryogenic microwave oscillators are secondary frequency standards in the microwave domain. The best of these oscillators\\u000a have demonstrated a short term frequency stability in the range 10?14 to a few times 10?16. The main application for these oscillators is as flywheel oscillators for the next generation of passive atomic frequency\\u000a standards, and as local oscillators in space telemetry ground

Anthony Mann

393

Microwave drilling of bones  

Microsoft Academic Search

This paper presents a feasibility study of drilling in fresh wet bone tissue in vitro using the microwave drill method [Derby et ab, 2002], toward testing its applicability in orthopaedic surgery. The microwave drill uses a near-field focused energy (typically, power under ?200 W at 2.45-GHz frequency) in order to penetrate bone in a drilling speed of ?1 mm\\/s. The

Yael Eshet; Ronit Rachel Mann; Abby Anaton; Tomer Yacoby; Amit Gefen; Eli Jerby

2006-01-01

394

47 CFR 101.141 - Microwave modulation.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Microwave modulation. 101.141 Section 101...SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.141 Microwave modulation. (a) Microwave...

2009-10-01

395

47 CFR 101.141 - Microwave modulation.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Microwave modulation. 101.141 Section 101...SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.141 Microwave modulation. (a) Microwave...

2010-10-01

396

Evaluation of the SMOS L-MEB passive microwave soil moisture retrieval algorithm  

Microsoft Academic Search

Soil moisture will be mapped globally by the European Soil Moisture and Ocean Salinity (SMOS) mission to be launched in 2009. The expected soil moisture accuracy will be 4.0 %v\\/v. The core component of the SMOS soil moisture retrieval algorithm is the L-band Microwave Emission of the Biosphere (L-MEB) model which simulates the microwave emission at L-band from the soil–vegetation

Rocco Panciera; Jeffrey P. Walker; Jetse D. Kalma; Edward J. Kim; Kauzar Saleh; Jean-Pierre Wigneron

2009-01-01

397

Search for anomalous long range interactions at highly relativistic velocities  

SciTech Connect

A high energy particle accelerator can be used to test the energy dependence of gravitational interactions between massive particles at highly relativistic velocities. The Tevatron is a circular ring which accelerates 10/sup 13/ protons to a peak energy of 800 GeV. The protons circulate in bunches spaced at the frequency of the accelerating RF field. The resulting structure of the beam provides a unique periodic source of gravity with strong components at several harmonics of the beam revolution frequency. A superconducting microwave cavity transducer was used as a detector for mechanical strains induced by the gravitational or other possible long range interactions. The detector was placed at a distance of 20 cm from the beam and was used to take 7 data sets during the January-April 1985 running of the Tevatron. At this time we set limits on the size of the induced metric strain of 1.5 x 10/sup -16/. Given the mechanical properties of the detector this implies a limit on the coupling G/sub A/ of an anomalous long range interaction G/sub A/ < 2 x 10/sup 19/ G/sub N/ where G/sub N/ is Newton's constant.

Reiner, P.J.

1985-01-01

398

Photometric Properties of Thermally Anomalous Terrain on Icy Saturnian Satellites  

NASA Astrophysics Data System (ADS)

Spectral maps of thermal emission from Mimas obtained by Cassini’s Composite InfraRed Spectrometer (CIRS) show that a V-shaped boundary, centered at 0° N and 180° W, divides relatively warm daytime temperatures from an anomalously cooler region at low to mid-latitudes on the leading hemisphere (Howett et al. 2011 Icarus 216, 211). This cooler region is also warmer at night, indicating that it has high thermal inertia, and also coincides in shape and location with that of high-energy electron deposition from Saturn’s magnetosphere (Roussos et al. 2007 JGR 112, A06214; Schenk et al. 2011 Icarus 211, 740). Global IR/UV color ratio maps assembled from Cassini Imaging Science Subsystem (ISS) images revealed a lens-shaped region of relatively blue terrain centered on the leading hemisphere (Schenk et al. 2011, Icarus). The area with low IR/UV ratio also coincides in shape and location with the region of high thermal inertia. A preliminary photometric analysis of Cassini ISS CL1 CL2 filter (centered at 611 nm) images using the Hapke (2008) model suggests that the high thermal inertia region on Mimas is rougher and more strongly backscattering than terrain with lower thermal inertia. Particles on the surface of the thermally anomalous terrain may have a more complex microtexture due to the high-energy electron bombardment. This work is supported by the NASA Cassini Data Analysis Program.

Annex, Andrew; Verbiscer, A. J.; Helfenstein, P.; Howett, C.; Schenk, P.

2013-10-01

399

Measurements of the GHz emission by a 3 MeV electron beam  

NASA Astrophysics Data System (ADS)

The MAYBE (Microwave Air Yield Beam) Experiment is dedicated to the study of the microwave emission from particle beams in light of its possible use for the detection of ultra high energy cosmic rays. Measurements of the microwave emission were performed at the 3 MeV electron beam in the Van de Graaff facility at the Argonne National Laboratory. Results include the measured spectrum between 1 and 15 GHz, the polarization, and the scaling of the emission power with respect to the beam intensity. MAYBE measurements provide further insight on microwave emission as a detection technique for ultra-high energy cosmic rays.

San Luis, P. Facal; Bohá?ová, M.; Bonifazi, C.; Cataldi, G.; Chemerisov, S.; de Mello Neto, J. R. T.; Fox, B.; Gorham, P. W.; Hojvat, C.; Hollon, N.; Meyhandan, R.; Monasor, M.; d'Orfeuil, B. Rouillé; Santos, E. M.; Pochez, J.; Privitera, P.; Spinka, H.; Verzi, V.; Zhou, J.

2013-05-01

400

The Microwave Air Yield Beam Experiment (MAYBE): measurement of GHz radiation for Ultra-High Energy Cosmic Rays detection  

NASA Astrophysics Data System (ADS)

We present measurements of microwave emission from an electron beam induced air plasma, performed at the electron Van de Graaff facility of the Argonne National Laboratory. Radio emission is studied over a wide range of frequencies between 1 and 15 GHz. This measurement provides further insight on microwave emission from extensive air showers as a novel detection technique for Ultra-High Energy Cosmic Rays.

Williams, Christopher; Bohacova, Martina; Bonifazi, Carla; Cataldi, Gabriella; Chemerisov, Sergey; de Mello Neto, Joao; Facal San Luis, Pedro; Fox, Brendan; Gorham, Peter W.; Hojvat, Carlos; Hollon, Nick; Meyhandan, Rishi; Reyes, Luis; Rouille D'Orfeuil, Benjamin; Santos, Edivaldo M.; Pochez, James; Privitera, Paolo; Spinka, Hal; Verzi, Valerio; Monasor, Maria; Zhou, Jing

2012-03-01

401

Parametric probability distributions for anomalous change detection  

SciTech Connect

The problem of anomalous change detection arises when two (or possibly more) images are taken of the same scene, but at different times. The aim is to discount the 'pervasive differences' that occur thoughout the imagery, due to the inevitably different conditions under which the images were taken (caused, for instance, by differences in illumination, atmospheric conditions, sensor calibration, or misregistration), and to focus instead on the 'anomalous changes' that actually take place in the scene. In general, anomalous change detection algorithms attempt to model these normal or pervasive differences, based on data taken directly from the imagery, and then identify as anomalous those pixels for which the model does not hold. For many algorithms, these models are expressed in terms of probability distributions, and there is a class of such algorithms that assume the distributions are Gaussian. By considering a broader class of distributions, however, a new class of anomalous change detection algorithms can be developed. We consider several parametric families of such distributions, derive the associated change detection algorithms, and compare the performance with standard algorithms that are based on Gaussian distributions. We find that it is often possible to significantly outperform these standard algorithms, even using relatively simple non-Gaussian models.

Theiler, James P [Los Alamos National Laboratory; Foy, Bernard R [Los Alamos National Laboratory; Wohlberg, Brendt E [Los Alamos National Laboratory; Scovel, James C [Los Alamos National Laboratory

2010-01-01

402

Arrival time of the front-edge in microwave propagation experiments  

NASA Astrophysics Data System (ADS)

The computation of the incoming wave-amplitude is reexamined even in relation to e.m. anomalous propagation. Specifically, we analyze the case in which a pole singularity is quite close to the instant of the beginning of the signal, and in which the contribution of the saddle-point, although appreciable, becomes less important. Along these lines, the experimental results can be well explained. Some results on electromagnetic propagation in the range of microwaves are reported and interpreted.

Ranfagni, A.; Mugnai, D.

2013-07-01

403

Design of a microwave calorimeter for the microwave tokamak experiment  

SciTech Connect

The initial design of a microwave calorimeter for the Microwave Tokamak Experiment is presented. The design is optimized to measure the refraction and absorption of millimeter rf microwaves as they traverse the toroidal plasma of the Alcator C tokamak. Techniques utilized can be adapted for use in measuring high intensity pulsed output from a microwave device in an environment of ultra high vacuum, intense fields of ionizing and non-ionizing radiation and intense magnetic fields. 16 refs.

Marinak, M. (California Univ., Berkeley, CA (USA))

1988-10-07

404

Streamlined Modeling for Characterizing Spacecraft Anomalous Behavior  

NASA Astrophysics Data System (ADS)

Anomalous behavior of on-orbit spacecraft can often be detected using passive, remote sensors which measure electro-optical signatures that vary in time and spectral content. Analysts responsible for assessing spacecraft operational status and detecting detrimental anomalies using non-resolved imaging sensors are often presented with various sensing and identification issues. Modeling and measuring spacecraft self emission and reflected radiant intensity when the radiation patterns exhibit a time varying reflective glint superimposed on an underlying diffuse signal contribute to assessment of spacecraft behavior in two ways: (1) providing information on body component orientation and attitude; and, (2) detecting changes in surface material properties due to the space environment. Simple convex and cube-shaped spacecraft, designed to operate without protruding solar panel appendages, may require an enhanced level of preflight characterization to support interpretation of the various physical effects observed during on-orbit monitoring. This paper describes selected portions of the signature database generated using streamlined signature modeling and simulations of basic geometry shapes apparent to non-imaging sensors. With this database, summarization of key observable features for such shapes as spheres, cylinders, flat plates, cones, and cubes in specific spectral bands that include the visible, mid wave, and long wave infrared provide the analyst with input to the decision process algorithms contained in the overall sensing and identification architectures. The models typically utilize baseline materials such as Kapton, paints, aluminum surface end plates, and radiators, along with solar cell representations covering the cylindrical and side portions of the spacecraft. Multiple space and ground-based sensors are assumed to be located at key locations to describe the comprehensive multi-viewing aspect scenarios that can result in significant specular reflection from both the sun and the underlying earth surface. The objects are modeled to be either tumbling or spin stabilized at key orientations in order to capture the complexity of the solar/earth incident illumination and the sensor viewing aspect conditions. Although these geometries and processes appear to be specialized and limited, they are sufficient to capture the principal observable features that are necessary for gaining insight into the complex issues of interpreting non-imaging sensor signals for monitoring the actual on-orbit spacecraft behavior changes. This talk has been prepared as a poster paper, to allow for engagement with conference participants on the presentation contents, and discussions for expansion of the material to include additional topical areas for future work, as appropriate. All discussions have been limited only to topics that could be discussed in the open format of the conference.

Klem, B.; Swann, D.

2011-09-01

405

Microwave radiometry and its potential applications in biology and medicine: experimental studies.  

PubMed

This paper presents experimental data on : (1) the natural emission of microwave radiation by biological systems, and (2) the effect of drugs as well as microwave radiation on specimen microwave emission. Experiments were conducted on guinea pigs, mice, rabbits, and human subjects. The results were obtained with two different radiometers, one of the correlation type and one of the Dicke type, operating in the X-band at about 9 GHz with a sensitivity of approximately 0.1 degrees K. The results demonstrate the feasibility of this technique and suggestions are made for its use in bilogy, medicine, and in the field of biocommunications. PMID:1234517

Bigu-del-Blanco, J; Romero-Sierra, C; Watts, D G

1975-01-01

406

Extinction Columns and Intrinsic X-Ray Spectra of the Anomalous X-Ray Pulsars  

Microsoft Academic Search

The X-ray spectra of anomalous X-ray pulsars have long been fit by smooth, empirical models such as the sum of a blackbody plus a power law. These reproduce the ~0.5-10 keV range well, but fail at lower and higher energies, grossly overpredicting the optical and underpredicting the hard X-ray emission. A poorly constrained source of uncertainty in determining the true,

Martin Durant; Marten H. van Kerkwijk

2006-01-01

407

Conductance deep-level transient spectroscopic study of anomalous hole trap in GaAs MESFETs  

Microsoft Academic Search

The anomalous `hole' trap like peaks observed in conductance DLTS spectra of GaAs MESFETs have been previously studied and have been associated with surface states present in the ungated regions at the GaAs-passivant interface. Besides these peaks, the conductance DLTS study of thermal emission and capture by these interface traps also indicates the presence of an associated surface conducting layer.

V. R. Balakrishnan; Vikram Kumar; Subhasis Ghosh

1998-01-01

408

Refinement of microwave vegetation indices  

Technology Transfer Automated Retrieval System (TEKTRAN)

Previous investigations have established the basis for a new type of vegetation index based on passive microwave satellite observations. These microwave vegetation indices (MVIs) have been qualitatively evaluated by examining global spatial and seasonal temporal features. Limited quantitative studie...

409

MICROWAVE TECHNOLOGY CHEMICAL SYNTHESIS APPLICATIONS  

EPA Science Inventory

Microwave-accelerated chemical syntheses in various solvents as well as under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although th...

410

MICROWAVE INSPECTION OF CIVIL STRUCTURES  

Microsoft Academic Search

This paper is devoted to microwave moisture-measurement (aquametry) and composition estimation of civil structures. In recent years considerable efforts have been made in applying microwave technique to test dielectric materials and metals. The first part of this \\

F. Volgyi

411

Simple Solar Microwave Burst Observed with High Spectral Resolution.  

National Technical Information Service (NTIS)

Many solar microwave bursts exhibit multicomponent spatial and spectral structure, which complicates efforts to determine source parameters from their radio emission. A small (SN/C1.0) flare that occurred on 1986 February 3 is dominated by a single, homog...

D. E. Gary G. J. Hurford

1988-01-01

412

High current density nanofilament cathodes for microwave amplifiers  

Microsoft Academic Search

We study high current density nanofilament cathodes for microwave amplifiers. Two different types of aligned nanofilament array have been studied: first, metallic nanowires grown by electrodeposition into nanoporous templates at very low temperature (T<100°C) on a silicon wafer; second, carbon nanotubes\\/nanofibers (CNs) grown by catalytic plasma enhanced chemical vapour deposition. The fabrication process and the field emission properties of these

J.-P. Schnell; E. Minoux; L. Gangloff; P. Vincent; P. Legagneux; D. Dieurnegard; J.-F. David; F. Peauger; L. Hudanski; K. B. K. Teo; R. Lacerda; M. Chhowalla; D. G. Hasko; H. Ahmed; G. A. J. Amaratunga; W. I. Milne; L. Vila; L. Dauginet-De Pra; S. Demoustier-Champagne; E. Ferain; R. Legras; L. Piraux; O. Groening; H. De Raedt; K. Michielsen

2004-01-01

413

TRMM Microwave Imager soil moisture mapping and flooding during CLASIC  

Technology Transfer Automated Retrieval System (TEKTRAN)

Passive microwave remote sensing has the potential to contribute to flood risk and impact assessment through the direct relationship between emissivity and soil moisture/standing water. Lower frequencies have greater potential because the impacts of atmospheric and vegetation attenuation are minimiz...

414

Microwave detection of Ultra-High Energy Cosmic Rays  

NASA Astrophysics Data System (ADS)

A novel detection technique for Ultra-High Energy Cosmic Rays based on microwave emission from the extensive air showers may provide large area coverage with 100% duty cycle at low cost. The status and prospects of several complementary R&D projects for GHz detectors is reviewed.

Privitera, P.

2011-09-01

415

The UARS and EOS Microwave Limb Sounder (MLS) Experiments  

Microsoft Academic Search

The Microwave Limb Sounder (MLS) experiments obtain measurements of atmospheric composition, temperature, and pressure by observations of millimeter- and submillimeter-wavelength thermal emission as the instrument field of view is scanned through the atmospheric limb. Features of the measurement technique include the ability to measure many atmospheric gases as well as temperature and pressure, to obtain measurements even in the presence

J. W. Waters; W. G. Read; L. Froidevaux; R. F. Jarnot; R. E. Cofield; D. A. Flower; G. K. Lau; H. M. Pickett; M. L. Santee; D. L. Wu; M. A. Boyles; J. R. Burke; R. R. Lay; M. S. Loo; N. J. Livesey; T. A. Lungu; G. L. Manney; L. L. Nakamura; V. S. Perun; B. P. Ridenoure; Z. Shippony; P. H. Siegel; R. P. Thurstans; R. S. Harwood; H. C. Pumphrey; M. J. Filipiak

1999-01-01

416

On the anomalous diffusion in nonisothermal plasma  

SciTech Connect

In nonisothermal plasmas at temperature T{sub e} Much-Greater-Than T{sub i} diffusion plays a decisive role at conditions of smooth inhomogeneity when the inhomogeneity size is much larger than {radical}(T{sub e}/T{sub i}) times the Debye radius. When the inhomogeneity is rather abrupt and this condition is violated, then during the spreading process the Maxwellian relaxation of ion charges becomes significant. Here, we consider these two phenomena together and refer to the anomalous character of diffusion, i.e., anomalous diffusion.

Rukhadze, A. A. [Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov Str. 38., Moscow 119991 (Russian Federation); Sadykova, S. P. [Humboldt-Universitaet zu Berlin, Newtonstr. 15, Berlin 12489 (Germany)

2012-07-15

417

Physics of the Microwave Oven  

ERIC Educational Resources Information Center

|This is the first of two articles about the physics of microwave ovens. This article deals with the generation of microwaves in the oven and includes the operation of the magnetrons, waveguides and standing waves in resonant cavities. It then considers the absorption of microwaves by foods, discussing the dielectric relaxation of water,…

Vollmer, Michael

2004-01-01

418

Physics of the Microwave Oven  

ERIC Educational Resources Information Center

This is the first of two articles about the physics of microwave ovens. This article deals with the generation of microwaves in the oven and includes the operation of the magnetrons, waveguides and standing waves in resonant cavities. It then considers the absorption of microwaves by foods, discussing the dielectric relaxation of water,…

Vollmer, Michael

2004-01-01

419

Microwave processing: fundamentals and applications  

Microsoft Academic Search

In microwave processing, energy is supplied by an electromagnetic field directly to the material. This results in rapid heating throughout the material thickness with reduced thermal gradients. Volumetric heating can also reduce processing times and save energy. The microwave field and the dielectric response of a material govern its ability to heat with microwave energy. A knowledge of electromagnetic theory

E. T. Thostenson; T.-W. Chou

1999-01-01

420

Quantitative evanescent microwave microscopy  

NASA Astrophysics Data System (ADS)

A vast variety of measurement techniques with high spatial resolution exist. However, a nondestructive technique that provides reliable, sensitive measurements of the complex electrical impedance with high spatial resolution was lacking. I contributed to the development of such a novel microscope, namely scanned evanescent microwave probe (SEMP). We developed experimental and theoretical methods for the evaluation of microwave complex impedance, which allows the quantitative imaging of the complex microwave dielectric constant (for insulators) and resistivity (for conductors) on a submicron length scale. In order to improve the spatial resolution and reduce the sample or tip damages, we also developed a means of distance regulation. With future improvement of the technique, resolutions approaching 20 nm may be expected. The microscope allows the measurement of variations in sample electronic properties on microscopic length scales. We demonstrated the capability to image samples varying from superconducting structures, semiconductors to ferroelectric materials. Such microscopes should find broad applications in various scientific areas and the semiconductor industry.

Duewer, Frederick William

2000-10-01

421

High power microwave generator  

DOEpatents

A device for producing high-powered and coherent microwaves is described. The device comprises an evacuated, cylindrical, and hollow real cathode that is driven to inwardly field emit relativistic electrons. The electrons pass through an internally disposed cylindrical and substantially electron-transparent cylindrical anode, proceed toward a cylindrical electron collector electrode, and form a cylindrical virtual cathode. Microwaves are produced by spatial and temporal oscillations of the cylindrical virtual cathode, and by electrons that reflex back and forth between the cylindrical virtual cathode and the cylindrical real cathode.

Minich, R.W.

1986-05-15

422

High power microwave generator  

DOEpatents

A device (10) for producing high-powered and coherent microwaves is described. The device comprises an evacuated, cylindrical, and hollow real cathode (20) that is driven to inwardly field emit relativistic electrons. The electrons pass through an internally disposed cylindrical and substantially electron-transparent cylindrical anode (24), proceed toward a cylindrical electron collector electrode (26), and form a cylindrical virtual cathode (32). Microwaves are produced by spatial and temporal oscillations of the cylindrical virtual cathode (32), and by electrons that reflex back and forth between the cylindrical virtual cathode (32) and the cylindrical real cathode (20).

Minich, Roger W. (Patterson, CA)

1988-01-01

423

Effects of hydrogen and amorphous carbon on the microwave absorption of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Plans for experiments studying the effects of hydrogen on the microwave absorption of carbon nanotubes are described, including details concerning the construction of experimental apparatus. Previous studies have shown that carbon nanotubes emit infrared, visible, and ultraviolet radiation under microwave fields. Theoretical studies of this phenomenon have suggested that either vibrational resonances or interactions of the microwaves with metal catalysts are responsible for the observed radiation emission. Our plans involve comparing the emission spectra for unpurified carbon nanotubes synthesized via arc-discharge using nickel and cobalt catalysts with single-walled carbon nanotubes synthesized via chemical vapor deposition using iron catalyst. Additionally, the emission spectra of samples that have undergone hydrogen absorption will be compared to samples that have not as part of an effort to help understand the mechanism(s) responsible for the exothermic reactions observed when nanotubes are irradiated with microwaves.

Sayavedra, C. R.; Gonzales, D.; Cavness, B. S.; Williams, S.

2012-03-01

424

Microwave processing of ceramic oxide filaments. Annual report, FY1997  

SciTech Connect

The objective of the microwave filament processing project is to develop microwave techniques to manufacture continuous ceramic oxide filaments. Microwave processing uses the volumetric absorption of microwave power in oxide filament tows to drive off process solvents, to burn out organic binders, and to sinter the dried fibers to produce flexible, high-strength ceramic filaments. The technical goal is to advance filament processing technology by microwave heating more rapidly with less energy and at a lower cost than conventional processing, but with the same quality as conventional processing. The manufacturing goal is to collaborate with the 3M Company, a US manufacturer of ceramic oxide filaments, to evaluate the technology using a prototype filament system and to transfer the microwave technology to the 3M Company. Continuous ceramic filaments are a principal component in many advanced high temperature materials like continuous fiber ceramic composites (CFCC) and woven ceramic textiles. The use of continuous ceramic filaments in CFCC radiant burners, gas turbines, waste incineration, and hot gas filters in U.S. industry and power generation is estimated to save at least 2.16 quad/yr by year 2010 with energy cost savings of at least $8.1 billion. By year 2010, continuous ceramic filaments and CFCC`s have the potential to abate pollution emissions by 917,000 tons annually of nitrous oxide and 118 million tons annually of carbon dioxide (DOE Report OR-2002, February, 1994).

Vogt, G.J.

1998-12-31

425

An Astrophysical Origin to Anomalous Spacecraft Accelerations  

Microsoft Academic Search

The anomalous and constant accelerations observed acting on spacecrafts are compared to a value obtained from a well-known astrophysical effect. The frequency shift method applied to the frequency ranges of spacecraft communications confirms the compatibility of the data with the known astrophysical data, to the point that, when combined, they give a much higher precision for the parameter known as

Roger Y. Gouin

426

Anomalous Language in Sexual Assault Trial Judgments  

Microsoft Academic Search

We analyzed the language in a random sample of recent Western Canadian trial judgments in cases of sexual assault. We discovered five anomalous themes: erotic\\/affectionate characterization of sexual assault; sexual assault as distinct from violence; appropriate resistance by the victim; the good character of the offender; and grammatically omitting the agent of the assault. These themes are illustrated in context

Linda Coates; Janet Beavin Bavelas; James Gibson

1994-01-01

427

Breather-induced anomalous charge diffusion  

Microsoft Academic Search

We present results on the diffusive motion of a charge interacting with the nonlinear dynamics of a thermalized underlying lattice. Signatures of anomalous diffusive properties are found at relatively high temperatures, where highly nonlinear excitations are present. A sublinear diffusion and a plateau appear before the standard long-time diffusion during the evolution of the mean-squared displacement and a significant degree

G. Kalosakas; K. L. Ngai; S. Flach

2005-01-01

428

Anomalous solvent extraction behavior of astatine  

Microsoft Academic Search

We studied the solvent extraction behavior of astatine and found the anomalous behavior of this element similar to radioiodine. Astatine was extracted into CS2 from acidic solution over a wide range of carrier iodine concentration. The distribution ratios of astatine were determined by measuring the -ray from 210 At with a Nal(TI) detector. A drastic change was observed around at

N. Takahashi; H. Baba

1997-01-01

429

Total least squares for anomalous change detection  

SciTech Connect

A family of difference-based anomalous change detection algorithms is derived from a total least squares (TLSQ) framework. This provides an alternative to the well-known chronochrome algorithm, which is derived from ordinary least squares. In both cases, the most anomalous changes are identified with the pixels that exhibit the largest residuals with respect to the regression of the two images against each other. The family of TLSQ-based anomalous change detectors is shown to be equivalent to the subspace RX formulation for straight anomaly detection, but applied to the stacked space. However, this family is not invariant to linear coordinate transforms. On the other hand, whitened TLSQ is coordinate invariant, and furthermore it is shown to be equivalent to the optimized covariance equalization algorithm. What whitened TLSQ offers, in addition to connecting with a common language the derivations of two of the most popular anomalous change detection algorithms - chronochrome and covariance equalization - is a generalization of these algorithms with the potential for better performance.

Theiler, James P [Los Alamos National Laboratory; Matsekh, Anna M [Los Alamos National Laboratory

2010-01-01

430

Discriminating between normal and anomalous random walks  

NASA Astrophysics Data System (ADS)

Commonly, normal diffusive behavior is characterized by a linear dependence of the second central moment on time, ?x2(t)??t , while anomalous behavior is expected to show a different time dependence, ?x2(t)??t? with ?<1 for subdiffusive and ?>1 for superdiffusive motions. Here we explore in details the fact that this kind of qualification, if applied straightforwardly, may be misleading: there are anomalous transport motions revealing perfectly “normal” diffusive character (?x2(t)??t) yet being non-Markov and non-Gaussian in nature. We use recently developed framework of Monte Carlo simulations which incorporates anomalous diffusion statistics in time and space and creates trajectories of such an extended random walk. For special choice of stability indices describing statistics of waiting times and jump lengths, the ensemble analysis of anomalous diffusion is shown to hide temporal memory effects which can be properly detected only by examination of formal criteria of Markovianity (fulfillment of the Chapman-Kolmogorov equation).

Dybiec, Bart?omiej; Gudowska-Nowak, Ewa

2009-12-01

431

Search for anomalous Z ? ??? events at LEP  

Microsoft Academic Search

We have searched for anomalous Z ? ??? events with the L3 detector at LEP. No significant deviations from the expected QED e+e? ? ??? events are observed. The branching ratio upper limit for a compoite Z decaying directly into three photons is found to be 1.0 × 10?5 at 95% C.L. The branching ratio upper limits for the process

M. Acciarri; A. Adam; O. Adriani; M. Aguilar-Benitez; S. Ahlen; J. Alcaraz; A. Aloisio; G. Alverson; M. G. Alviggi; G. Ambrosi; Q. An; H. Anderhub; A. L. Anderson; V. P. Andreev; T. Angelescu; L. Antonov; D. Antreasyan; G. Alkhazov; P. Arce; A. Arefiev; T. Azemoon; T. Aziz; P. V. K. S. Baba; P. Bagnaia; J. A. Bakken; L. Baksay; R. C. Ball; S. Banerjee; K. Banicz; R. Barillère; L. Barone; A. Baschirotto; M. Basile; R. Battiston; A. Bay; F. Becattini; U. Becker; F. Behner; Gy. L. Bencze; J. Berdugo; P. Berges; B. Bertucci; B. L. Betev; M. Biasini; A. Biland; G. M. Bilei; R. Bizzarri; J. J. Blaising; G. J. Bobbink; R. Bock; A. Böhm; B. Borgia; A. Boucham; D. Bourilkov; M. Bourquin; D. Boutigny; B. Bouwens; E. Brambilla; J. G. Branson; V. Brigljevic; I. C. Brock; M. Brooks; A. Bujak; J. D. Burger; W. J. Burger; C. Burgos; J. Busenitz; A. Buytenhuijs; A. Bykov; X. D. Cai; M. Capell; G. Cara Romeo; M. Caria; G. Carlino; A. M. Cartacci; J. Casaus; R. Castello; N. Cavallo; M. Cerrada; F. Cesaroni; M. Chamizo; Y. H. Chang; U. K. Chaturvedi; M. Chemarin; A. Chen; C. Chen; G. Chen; H. F. Chen; H. S. Chen; M. Chen; G. Chiefari; C. Y. Chien; M. T. Choi; S. Chung; L. Cifarelli; F. Cindolo; C. Civinini; I. Clare; R. Clare; T. E. Coan; H. O. Cohn; G. Coignet; N. Colino; V. Commichau; S. Costantini; F. Cotorobai; B. de la Cruz; X. T. Cui; X. Y. Cui; T. S. Dai; R. D'Alessandro; R. de Asmundis; A. Degré; K. Deiters; E. Dénes; P. Denes; F. DeNotaristefani; D. DiBitonto; M. Diemoz; H. R. Dimitrov; C. Dionisi; M. Dittmar; I. Dorne; M. T. Dova; E. Drago; D. Duchesneau; F. Duhem; P. Duinker; I. Duran; S. Dutta; S. Easo; H. El Mamouni; A. Engler; F. J. Eppling; F. C. Erné; P. Extermann; R. Fabbretti; M. Fabre; S. Falciano; A. Favara; J. Fay; M. Felcini; T. Ferguson; D. Fernandez; G. Fernandez; F. Ferroni; H. Fesefeldt; E. Fiandrini; J. H. Field; F. Filthaut; P. H. Fisher; G. Forconi; L. Fredj; K. Freudenreich; M. Gailloud; Yu. Galaktionov; E. Gallo; S. N. Ganguli; P. Garcia-Abia; S. S. Gau; S. Gentile; J. Gerald; N. Gheordanescu; S. Giagu; S. Goldfarb; J. Goldstein; Z. F. Gong; E. Gonzalez; A. Gougas; D. Goujon; G. Gratta; M. W. Gruenewald; C. Gu; M. Guanziroli; V. K. Gupta; A. Gurtu; H. R. Gustafson; L. J. Gutay; B. Hartmann; A. Hasan; D. hauschildt; J. T. He; T. Hebbeker; M. Hebert; A. Hervé; K. Hilgers; H. Hofer; H. Hoorani; S. R. Hou; G. Hu; B. Ille; M. M. Ilyas; V. Innocente; H. Janssen; B. N. Jin; L. W. Jones; P. de Jong; I. Josa-Mutuberria; A. Kasser; R. A. Khan; Yu. Kamyshkov; P Kapinos; J. S. Kapustinsky; Y. Karyotakis; M. Kaur; S. Khokhar; M. N. Kienzle-Focacci; D. Kim; J. K. Kim Do; S. C. Kim; Y. G. Kim; W. W. Kinnison; A. Kirkby; D. Kirkby; J. Kirkby; S. Krsch; W. Kittel; A. Klimentov; A. C. König; E. Koffeman; O. Kornadt; V. Koutsenko; A. Koulbardis; R. W. Kraemer; T. Kramer; V. R. Krastev; W. Krenz; H. Kuijten; A. Kunin; P. Ladron de Guevara; G. Landi; S. Lanzano; P. Laurikainen; A. Lebedev; P. Lebrun; P. Lecomte; P. Lecoq; P Le Coultre; D. M. Lee; J. S. Lee; K. Y. Lee; I. Leedom; C. Leggett; J. M. LeGoff; R. Leiste; M. Lenti; E. Leonardi; P Levtchenko; C. Li; E. Lieb; W. T. Lin; E. L. Linde; B. Lindemann; L. Lista; Y. Liu; W. Lohmann; E. Longo; W. Lu; Y. S. Lu; J. M. Lubbers; K. Liibelsmeyer; C. Luci; D. Luckey; L. Ludovici; L. Luminari; W. Lustermann; W. G. Ma; M. MacDermott; M. Maity; L. Malgeri; R. Malik; A. Malinin; C. Maña; S. Mangla; M. Maolinbay; P. Marchesini; A. Marin; J. P Martin; F. Marzano; G. G. G. Massaro; K. Mazumdar; T. McMahon; D. McNally; S. Mele; M. Merkah; L. Merola; M. Meschini; W. J. Metzger; Y. Mi; A. Mihu; G. B. Mills; Y. Mir; G. Mirabelli; J. Mnich; M. Möller; V. Monaco; B. Monteleoni; R. Morand; S. Morganti; N. E. Moulai; R. Mount; S. Müller; E. Nagy; M. Napolitano; F. Nessi-Tedaldi; H. Newman; M. A. Niaz; A. Nippe; H. Nowak; G. Organtini; R. Ostonen; D. Pandoulas; S. Paoletti; P. Paolucci; G. Pascalei; G. Passaleva; S. Patricelli; T. Paul; M. Pauluzzi; C. Paus; F. Pauss; Y. J. Pei; S. Pensotti; D. Perret-Gallix; A. Pevsner; D. Piccolo; M. Pieri; J. C. Pinto; P. A. Piroué; E. Pistolesi; F. Plasil; V. Plyaskin; M. Pohl; V. Pojidaev; H. Postema; N. Produit; J. M. Qian; K. N. Qureshi; R. Raghavan; G. Rahal-Callot; P. G. Rancoita; M. Rattaggi; G. Raven; P Razis; K. Read; M. Redaelli; D. Ren; Z. Ren; M. Rescigno; S. Reucroft; A. Ricker; S. Riemanna; B. C. Riemers; K. Riles; O. Rind; H. A. Rizvi; S. Ro; A. Robohm; F. J. Rodriguez; B. P. Roe; M. Röhner; S. Röhner; L. Romero; S. Rosier-Lees; R. Rosmalen; Ph. Rosselet; W. van Rossum; S. Roth; A. Rubbia; J. A. Rubio; H. Rykaczewski; J. Salicio; E. Sanchez; G. S. Sanders; A. Santocchia; M. E. Sarakinos; S. Sarkar; G. Sartorelli; M. Sassowsky; G. Sauvage; C. Schäfer; V. Schegelsky; D. Schmitz; P Schmitz; M. Schneegans; N. Scholz; H. Schopper; D. J. Schotanus; S. Shotkin; H. J. Schreiber; J. Shukla; R. Schulte; K. Schultze

1995-01-01

432

Anomalous left coronary artery in a calf.  

PubMed

An anomalous left coronary artery was seen arising from an ostium in the pulmonary artery in a 4-month-old Hereford calf. Endocardial fibrosis was found in the left atrium and left ventricle. The mitral valve was dilated and thickened. A normal right coronary artery originated from the aorta. PMID:711589

Sandusky, G E; Smith, C W

1978-09-01

433

Non-military microwave applications  

NASA Astrophysics Data System (ADS)

The nonmilitary applications of microwave technology in medicine, communications, and agriculture are discussed. Particular attention is given to a microwave multichannel multipoint video distribution system (a broadcasting system with up to 20 programs drawn from satellites, video tape libraries, and locally generated material); microwaves used in DBS distribution; satellite receivers for data communications; microwave thermography used for early cancer detection, brain temperature measurements, and appendicitis diagnosis; an experimental Doppler radar assembly for guiding robots walking on a factory floor; and an agricultural application where microwaves are used to break down slugs in soil and thus improve potato and grain crops. Schematic diagrams are included.

Bierman, Howard

1990-04-01

434

Anomalous Extensor Muscles of the Hand: A Review  

Microsoft Academic Search

Anomalous extensor muscles of the hand are not uncommon. Well-recognized anomalies ? anomalous extensor indicis proprius, extensor digitorum brevis manus, extensor medii proprius, and extensor indicis et medii communis are reviewed and discussed in detail. Anomalous extensor indicis proprius and extensor digitorum brevis manus may occasionally give rise to dorsal wrist pain and the diagnosis is often confused especially in

Swee T. Tan; Paul J. Smith

1999-01-01

435

The Comprehension of Anomalous Sentences: Evidence from Structural Priming  

ERIC Educational Resources Information Center

|We report three experiments investigating how people process anomalous sentences, in particular those in which the anomaly is associated with the verb. We contrast two accounts for the processing of such anomalous sentences: a syntactic account, in which the representations constructed for anomalous sentences are similar in nature to the ones…

Ivanova, Iva; Pickering, Martin J.; Branigan, Holly P.; McLean, Janet F.; Costa, Albert

2012-01-01

436

The Comprehension of Anomalous Sentences: Evidence from Structural Priming  

ERIC Educational Resources Information Center

We report three experiments investigating how people process anomalous sentences, in particular those in which the anomaly is associated with the verb. We contrast two accounts for the processing of such anomalous sentences: a syntactic account, in which the representations constructed for anomalous sentences are similar in nature to the ones…

Ivanova, Iva; Pickering, Martin J.; Branigan, Holly P.; McLean, Janet F.; Costa, Albert

2012-01-01

437

Big Bang leftovers in the microwave: Cosmology with the cosmic microwave background radiation  

NASA Astrophysics Data System (ADS)

We combine detections of anisotropy in the Cosmic Microwave Background radiation with observations of inhomogeneity in the large-scale distribution of galaxies to test the predictions of models of cosmological structure formation. This combination probes spatial scales varying by three orders of magnitude, including a significant region where the two types of data overlap. We examine Cold Dark Matter models with adiabatic density perturbations, isocurvature models, and a topological defects model. We set upper limits on the neutrino mass and find the primordial power spectrum needed to reconcile an apparent disagreement between structure formation observations and direct observations of cosmological parameters. Present and future observations of Cosmic Microwave Background anisotropy suffer from foreground contamination. We develop detailed predictions for microwave emission from radio and infrared-bright galaxies and the Sunyaev-Zel'dovich effect from clusters. We present realistic simulations of the microwave sky, produced as part of the ``WOMBAT Challenge'' exercise, and introduce a pixel-space method for subtracting foreground contamination which can be tested on these simulations.

Gawiser, Eric Joseph

1999-11-01

438

Variable frequency microwave furnace system  

DOEpatents

A variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency microwave furnace system includes a microwave signal generator or microwave voltage-controlled oscillator for generating a low-power microwave signal for input to the microwave furnace. A first amplifier may be provided to amplify the magnitude of the signal output from the microwave signal generator or the microwave voltage-controlled oscillator. A second amplifier is provided for processing the signal output by the first amplifier. The second amplifier outputs the microwave signal input to the furnace cavity. In the preferred embodiment, the second amplifier is a traveling-wave tube (TWT). A power supply is provided for operation of the second amplifier. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. 5 figs.

Bible, D.W.; Lauf, R.J.

1994-06-14

439

Variable frequency microwave furnace system  

DOEpatents

A variable frequency microwave furnace system (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34) for testing or other selected applications. The variable frequency microwave furnace system (10) includes a microwave signal generator (12) or microwave voltage-controlled oscillator (14) for generating a low-power microwave signal for input to the microwave furnace. A first amplifier (18) may be provided to amplify the magnitude of the signal output from the microwave signal generator (12) or the microwave voltage-controlled oscillator (14). A second amplifier (20) is provided for processing the signal output by the first amplifier (18). The second amplifier (20) outputs the microwave signal input to the furnace cavity (34). In the preferred embodiment, the second amplifier (20) is a traveling-wave tube (TWT). A power supply (22) is provided for operation of the second amplifier (20). A directional coupler (24) is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Bible, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN)

1994-01-01

440

Anomalous diffusion as a stochastic component in the dynamics of complex processes  

NASA Astrophysics Data System (ADS)

We propose an interpolation expression using the difference moment (Kolmogorov transient structural function) of the second order as the average cha