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1

Anomalous Microwave Emission  

E-print Network

Improved knowledge of diffuse Galactic emission is important to maximize the scientific return from scheduled CMB anisotropy missions. Cross-correlation of microwave maps with maps of the far-IR dust continuum show a ubiquitous microwave emission component whose spatial distribution is traced by far-IR dust emission. The spectral index of this emission, beta_{radio} = -2.2 (+0.5 -0.7) is suggestive of free-free emission but does not preclude other candidates. Comparison of H-alpha and microwave results show that both data sets have positive correlations with the far-IR dust emission. Microwave data, however, are consistently brighter than can be explained solely from free-free emission traced by H-alpha. This ``anomalous'' microwave emission can be explained as electric dipole radiation from small spinning dust grains. The anomalous component at 53 GHz is 2.5 times as bright as the free-free emission traced by H-alpha, providing an approximate normalization for models with significant spinning dust emission.

A. Kogut

1999-02-22

2

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

3

VizieR Online Data Catalog: Anomalous microwave emission in Galactic clouds (Planck+, 2014)  

NASA Astrophysics Data System (ADS)

Anomalous microwave emission (AME) is believed to be due to electric dipole radiation from small spinning dust grains. The aim of this paper is a statistical study of the basic properties of AME regions and the environment in which they emit. We used WMAP and Planck maps, combined with ancillary radio and IR data, to construct a sample of 98 candidate AME sources, assembling SEDs for each source using aperture photometry on 1°-smoothed maps from 0.408GHz up to 3000GHz. Each spectrum is fitted with a simple model of free-free, synchrotron (where necessary), cosmic microwave background (CMB), thermal dust, and spinning dust components. We find that 42 of the 98 sources have significant (>5?) excess emission at frequencies between 20 and 60GHz. An analysis of the potential contribution of optically thick free-free emission from ultra-compact HII regions, using IR colour criteria, reduces the significant AME sample to 27 regions. The spectrum of the AME is consistent with model spectra of spinning dust. Peak frequencies are in the range 20-35GHz except for the California nebula (NGC1499), which appears to have a high spinning dust peak frequency of (50+/-17)GHz. The AME regions tend to be more spatially extended than regions with little or no AME. The AME intensity is strongly correlated with the sub-millimetre/IR flux densities and comparable to previous AME detections in the literature. AME emissivity, defined as the ratio of AME to dust optical depth, varies by an order of magnitude for the AME regions. The AME regions tend to be associated with cooler dust in the range 14-20K and an average emissivity index, ?d, of +1.8, while the non-AME regions are typically warmer, at 20-27K. In agreement with previous studies, the AME emissivity appears to decrease with increasing column density. This supports the idea of AME originating from small grains that are known to be depleted in dense regions, probably due to coagulation onto larger grains. We also find a correlation between the AME emissivity (and to a lesser degree the spinning dust peak frequency) and the intensity of the interstellar radiation field, G0. Modelling of this trend suggests that both radiative and collisional excitation are important for the spinning dust emission. The most significant AME regions tend to have relatively less ionized gas (free-free emission), although this could be a selection effect. The infrared excess, a measure of the heating of dust associated with HII regions, is typically >4 for AME sources, indicating that the dust is not primarily heated by hot OB stars. The AME regions are associated with known dark nebulae and have higher 12?m/25?m ratios. The emerging picture is that the bulk of the AME is coming from the polycyclic aromatic hydrocarbons and small dust grains from the colder neutral interstellar medium phase. (1 data file).

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Alves, M. I. R.; Arnaud, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoit-Levy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Cardoso, J.-F.; Casassus, S.; Catalano, A.; Chamballu, A.; Chen, X.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Couchot, F.; Crill, B. P.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; De Rosa, A.; de Zotti, G.; Delabrouille, J.; Desert, F.-X.; Dickinson, C.; Diego, J. M.; Donzelli, S.; Dore, O.; Dupac, X.; Ensslin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Franceschi, E.; Galeotta, S.; Ganga, K.; Genova-Santos, R. T.; Ghosh, T.; Giard, M.; Gonzalez-Nuevo, J.; Gorski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D. L.; Helou, G.; Hernandez-Monteagudo, C.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Hornstrup, A.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Keihaenen, E.; Keskitalo, R.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Laehteenmaeki, A.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leonardi, R.; Liguori, M.; Lilje, P. B.; Linden-Vornle, M.; Lopez-Caniego, M.; Macias-Perez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Marshall, D. J.; Martin, P. G.; Martinez-Gonzalez, E.; Masi, S.; Massardi, M.; Matarrese, S.; Mazzotta, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Miville-Deschenes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Naselsky, P.; Nati, F.; Natoli, P.; Norgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Patanchon, G.; Pearson, T. J.; Peel, M.; Perdereau, O.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Rebolo, R.; Reich, W.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rubino-Martin, J. A.; Rusholme, B.; Sandri, M.; Savini, G.; Scott, D.; Spencer, L. D.; Stolyarov, V.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Tibbs, C. T.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Varis, J.; Verstraete, L.; Vielva, P.; Villa, F.; Wandelt, B. D.; Watson, R.; Wilkinson, A.; Ysard, N.; Yvon, D.; Zacchei, A.; Zonca, A.

2014-07-01

4

Searching for the Culprit of Anomalous Microwave Emission: An AKARI PAHrange Analysis of Probable Electric Dipole Emitting Regions  

NASA Astrophysics Data System (ADS)

In the march forward of interstellar medium inquiry, many new species of interstellar dust have been modelled and discovered. The modes by which these species interact and evolve are beginning to be understood, but in recent years a peculiar new feature has appeared in microwave surveys. Anomalous microwave emission (AME), appearing between 10 and 90Ghz, has been correlated with thermal dust emission, leading to the popular suggestion that this anomaly is electric dipole emission from spinning dust [2]. The observed frequencies suggest that spinning grains should be on the order of 10nm in size, hinting at poly-cyclic aromatic hydrocarbon molecules. We present data from AKARI/Infrared Camera [1], due to the effective PAH/Unidentified Infrared Band (UIR) coverage of its 9um survey to investigate their role within a few regions showing strong AME in the Planck low frequency data. We include the well studied Perseus and ?Ophiuchi clouds . We use the IRAS/IRIS 100µm data to account for the overall dust temperature. We present our results as abundance maps for dust emitting around 9µm, and 100µm. Part of the AME in these regions may actually be attributed to thermal dust emission, or the star forming nature of these targets is masking the vibrational modes of PAHs which should be present there, suggesting further investigation for various galactic environments.

Bell, A. C.; Onaka, T.; Sakon, I.; Ishihara, D.; Kaneda, H.; Lee, H. G.; Itoh, M.; Ohsawa, R.; Hammonds, M.

5

Diffuse Microwave Emission Survey  

E-print Network

The Diffuse Microwave Emission Survey (DIMES) has been selected for a mission concept study for NASA's New Mission Concepts for Astrophysics program. DIMES will measure the frequency spectrum of the cosmic microwave background and diffuse Galactic foregrounds at centimeter wavelengths to 0.1% precision (0.1 mK), and will map the angular distribution to 20 muK per 6 degree field of view. It consists of a set of narrow-band cryogenic radiometers, each of which compares the signal from the sky to a full-aperture blackbody calibration target. All frequency channels compare the sky to the same blackbody target, with common offset and calibration, so that deviations from a blackbody spectral shape may be determined with maximum precision. Measurements of the CMB spectrum complement CMB anisotropy experiments and provide information on the early universe unobtainable in any other way; even a null detection will place important constraints on the matter content, structure, and evolution of the universe. Centimeter-wavelength measurements of the diffuse Galactic emission fill in a crucial wavelength range and test models of the heat sources, energy balance, and composition of the interstellar medium.

Al Kogut

1996-07-19

6

Microwave emission and scattering from vegetated terrain  

E-print Network

MICROWAVE EMISSION AND SCATTERING FROM VEGETATED TERRAIN A Thesis by TERRELL GENE SIBLEY Submitted to the Graduate College of Texas A)M Vniversity in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1973... Major Subject: Electrical Engineering MICROWAVE EMISSION AND SCATTERING FROM VEGETATED TERRAIN A Thesis by TERRELL GENE SIBLEY Approved as to style and content by: iran o o t e ea epart nt em er Aug us t 19 7 3 ABSTRACT Microwave Emission...

Sibley, Terrell Gene

2012-06-07

7

Microwave emission of sonoluminescing bubbles.  

PubMed

Kordomenos et al. have attempted to measure single bubble sonoluminescence (SBSL) emission in the microwave window of water in a band of frequencies ranging from 1.65 GHz to 2.35 GHz [Phys. Rev. E 59, 1781 (1999)]. The sensitivity of the experiment was such that signals greater than 1 nW would have been detected. We show here that this upper bound is compatible with the radiation processes that we think generate significant emission at optical frequencies, electron-neutral and electron-ion bremsstrahlung. In fact, we argue that, almost independently of the specific assumptions concerning the hydrodynamics or the nature of the radiative processes, SBSL intensities exceeding that upper bound can hardly be expected. PMID:12241521

Hammer, Dominik; Frommhold, Lothar

2002-07-01

8

Emissions from Cooking Microwave Popcorn  

Microsoft Academic Search

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

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

2007-01-01

9

Microwave emissions from police radar  

E-print Network

The purpose of this study was to evaluate police officers exposures to microwaves emitted by traffic radar units at the ocular and testicular level. Additionally, comparisons were made of the radar manufacturers published maximum power density...

Fink, John Michael

2012-06-07

10

Beyond Anderson Localization in 1D: Anomalous Localization of Microwaves in Random Waveguides  

E-print Network

Experimental evidence demonstrating that anomalous localization of waves can be induced in a controllable manner is reported. A microwave waveguide with dielectric slabs randomly placed is used to confirm the presence of anomalous localization. If the random spacing between slabs follows a distribution with a power-law tail (L\\'evy-type distribution), unconventional properties in the microwave-transmission fluctuations take place revealing the presence of anomalous localization. We study both theoretically and experimentally the complete distribution of the transmission through random waveguides characterized by $\\alpha=1/2$ ("L\\'evy waveguides") and $\\alpha=3/4$, $\\alpha$ being the exponent of the power-law tail of the L\\'evy-type distribution. As we show, the transmission distributions are determined by only two parameters, both of them experimentally accessible. Effects of anomalous localization on the transmission are compared with those from the standard Anderson localization.

Fernández-Marín, A A; Carbonell, J; Cervera, F; Sánchez-Dehesa, J; Gopar, V A

2014-01-01

11

Microwave Emission by Dust: Mechanisms, Properties and Prospects for ISM Studies  

E-print Network

I review my work with Bruce Draine on dust emissivity at microwave frequencies (3 cm - 3 mm). This emissivity explains the recently detected "anomalous" component of the galactic foreground emission. Both small (a<0.001 micron) and large grains contribute to this emission. Small grains have electric dipole moments and emit while they rotate; the microwave emission of large grains is mostly due to magneto-dipole radiation. Most efficient magneto-dipole emitters are strongly magnetic, e.g. ferrimagnetic or ferromagnetic, materials. The relative role of the two mechanisms can be established through observations of microwave emissivity from dark clouds. New microwave window is a window of opportunity for interstellar studies. Magnetic fields inside dark clouds may be successfully studied via microwave polarization. Microwave emissivity constrains the abundance of strongly magnetic materials. For instance, the available data at 90 GHz indicate that not more than 5% of interstellar Fe is in the form of metallic iron grains or inclusions (e.g., in ``GEMS''). Future missions, e.g. MAP and PLANCK, will bring a wealth of microwave data that can be successfully used to study ISM. Such a study would be appreciated by cosmologists who franticly try to remove all foregrounds from their data.

Lazarian A

1998-11-03

12

Anomalous microwave spectra of snow cover observed from Special Sensor Microwave/Imager measurements  

NASA Astrophysics Data System (ADS)

Brightness temperature spectra measured by the Special Sensor Microwave/Imager (SSM/I) flown onboard F8 and F14 satellites of the U.S. Defense Meteorological Satellite Program (DMSP) during the 1987-1988 and 1997-1998 winter periods are analyzed concurrently with the data from snow monitoring stations over the former Soviet Union. Extensive analysis reveals the existence of two anomalies in the microwave thermal radiation spectra of snow cover. It is shown that in the beginning of winter the SSM/I measurements at 19, 37, and 85 GHz generally follow a classical pattern; that is, the brightness temperatures decrease for both increasing snow depth and increasing frequency. Dramatic departures from this behavior is observed around the middle of winter: The brightness temperatures reach a minimum and then begin to increase despite the fact that the snow depth remains constant or even continues to grow. Statistical analysis of the snow pack characteristics and SSM/I measurements is presented around the time when the brightness temperatures reach a minimum. The anomalous spectral characteristics are analyzed using a two-stream radiative transfer model and dense media theory. It is shown how metamorphic changes in the snow crystalline structure are responsible for the brightness temperature minimum. The second departure from the normal snow signature is the inversion of brightness temperature spectra; that is, the higher-frequency brightness temperature is greater than the low-frequency measurements. It is shown that this phenomenon, observed previously over Greenland and Antarctica, is much more extensive. Radiative transfer simulations were used to show that a dense layer of surface crust on top of old coarse-grained snow can produce the invented brightness temperature spectrum.

Rosenfeld, Simon; Grody, Norman

2000-06-01

13

Modeling microwave emission spectra of layered snowpacks  

Microsoft Academic Search

A thermal microwave emission model of layered snowpacks (MEMLS) (Wiesmann and Matzler, 1997) was developed for the frequency range, 5 to 100 GHz. It is based on radiative transfer, using six-flux theory to describe multiple volume scattering and absorption, including radiation trapping due to internal reflection and a combination of coherent and incoherent superpositions of reflections between layer interfaces. The

A. Wiesmann; C. Hatzler; D. Hiltbrunner

1998-01-01

14

The Anomalous Infrared Emission of Abell 58  

E-print Network

We present a new model to explain the excess in mid and near infrared emission of the central, hydrogen poor dust knot in the planetary nebula (PN) Abell 58. Current models disagree with ISO measurement because they apply an average grain size and equilibrium conditions only. We investigate grain size distributions and temperature fluctuations affecting infrared emission using a new radiative transfer code and discuss in detail the conditions requiring an extension of the classical description. The peculiar infrared emission of V605 Aql, the central dust knot in Abell 58, has been modeled with our code. V605 Aql is of special interest as it is one of only three stars ever observed to move from the evolutionary track of a central PN star back to the post-AGB state.

Josef Koller; Stefan Kimeswenger

2001-05-30

15

Microwave emissions from police radar.  

PubMed

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 research institute provided 54 radar units for evaluation; 17 different models, encompassing 4 frequency bands and 3 antenna configurations, were included. Four of the 986 measurements taken exceeded the 5 mW/cm2 limit accepted by the International Radiation Protection Association and the National Council on Radiation Protection and Measurement, though none exceeded the American Conference of Governmental Industrial Hygienists, American National Standards Institute, Institute of Electrical and Electronic Engineers, or Occupational Safety and Health Administration standard of 10 mW/cm2. The four high measurements were maximum power density readings taken directly in front of the radar. Of the 812 measurements taken at the officers' seated ocular and testicular positions, none exceeded 0.04 mW/cm2; the highest of these (0.034 mW/cm2) was less than 1% of the most conservative current safety standards. High exposures in the limited region directly in front of the radar aperture are easily avoided with proper training. Results of this study indicate that police officer exposure to microwave radiation is apparently minimal. However, because of uncertainty in the medical and scientific communities concerning nonionizing radiation, it is recommended that law enforcement agencies implement a policy of prudent avoidance, including purchasing units with the lowest published maximum power densities, purchasing dash/rear deck-mounted units with antennae mounted outside the patrol vehicle, and training police officers to use the "stand-by" mode when not actually using radar. PMID:10671181

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

1999-01-01

16

Quiescent Microwave Emission from LateType Stars  

E-print Network

intense microwave radiation of the quiet Sun, which at centimeter wavelengths comes from freeQuiescent Microwave Emission from Late­Type Stars Manuel G¨udel Joint Institute for Laboratory of low­level, ``quiescent'' microwave radiation. This emission is, in most cases, attributed

Guedel, Manuel

17

Anomalous photoelectric emission from Ag on zinc-phthalocyanine film  

NASA Astrophysics Data System (ADS)

Photoelectric emission from organic and metal thin films is generally observed with irradiation of photon energy larger than 4 eV. In this paper, however, we report photoelectric emission from Ag on a zinc-phthalocyanine (ZnPc) layer at a photon energy of 3.4 eV. The threshold energy for this photoelectric emission is much smaller than the work function of Ag estimated by conventional photoelectron spectroscopy. The photoelectric emission by low-energy photons is significant for Ag thicknesses of less than 1 nm. Photoelectron spectroscopy and morphological study of the Ag/ZnPc suggest that the anomalous photoelectric emission from the Ag surface is caused by a vacuum level shift at the Ag/ZnPc interface and by surface plasmons of the Ag nanoparticles.

Tanaka, Senku; Otani, Tomohiro; Fukuzawa, Ken; Ogawa, Koji; Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao; Hiromitsu, Ichiro

2014-05-01

18

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

19

Microwave ISM Emission Observed by WMAP  

E-print Network

We investigate the nature of the diffuse Galactic emission in the Wilkinson Microwave Anisotropy Probe (WMAP) temperature anisotropy data. Substantial dust-correlated emission is observed at all WMAP frequencies, far exceeding the expected thermal dust emission in the lowest frequency channels (23, 33, 41 GHz). The WMAP team (Bennett et al.) interpret this emission as dust-correlated synchrotron radiation, attributing the correlation to the natural association of relativistic electrons produced by SNae with massive star formation in dusty clouds, and deriving an upper limit of 5% on the contribution of Draine & Lazarian spinning dust at K-band (23 GHz). We pursue an alternative interpretation that much, perhaps most, of the dust-correlated emission at these frequencies is indeed spinning dust, and explore the spectral dependence on environment by considering a few specific objects as well as the full sky average. Models similar to Draine & Lazarian spinning dust provide a good fit to the full-sky data. The full-sky fit also requires a significant component with free-free spectrum uncorrelated with \\Halpha, possibly hot (~million K) gas within 30 degrees of the Galactic center.

Douglas P. Finkbeiner

2003-11-24

20

Retrieval of microwave surface emissivities at TMI frequencies in Shouxian  

NASA Astrophysics Data System (ADS)

Using a microwave radiative transfer model, atmospheric sounding profiles, satellite brightness temperatures, and some surface observed measurements under cloud-free conditions, surface emissivities at the frequencies of TRMM/TMI (Tropical Rainfall Measuring Mission Microwave Imager) at Shouxian in HUBEX (Huaihe River Basin Energy and Water Cycle Experiment) are retrieved. Compared to the microwave surface emissivities with changing conditions of the surface, it is found that the microwave emissivities have some sensitive variability with the conditions of the surface, and the variability is reasonable. In the calculation, the surface air temperatures are assumed to equal the surface skin temperatures, and only the emissivity at Shouxian is calculated; the calculation of the emissivities over the region of HUBEX needs more measurements.

Hong, Gang; Heygster, Georg; Kunzi, Klaus; Li, Wanbiao; Zhu, Yuanjing; Zhao, Bolin

2003-06-01

21

Extracting Microwave Emissivity Characteristics over City using AMSR-E  

NASA Astrophysics Data System (ADS)

The spectrums of different land types are very important in the application of remote sensing. Different spectrums of different land types can be used in surface classification, change detection, and so on. The microwave emissivity over land is the foundation of land parameters retrieval using passive microwave remote sensing. It depends on land type due to different objects’ structure, moisture and roughness on the earth. It has shown that the land surface microwave emissivity contributed to atmosphere temperature and moisture retrieval. Meanwhile, it depends on land type, vegetation cover, and moisture et al.. There are many researches on microwave emissivity of various land types, such as bare soil, vegetation, snow, but city was less mentioned [1]. However, with the development of society, the process of urbanization accelerated quickly. The area of city expanded fast and the fraction of city area increased in one microwave pixel, especially in The North China Plain (about 30%). The passive microwave pixel containing city has impact on satellite observation and surface parameters retrieval then. So it is essential to study the emissivity of city in order to improve the accuracy of land surface parameters retrieval from passive microwave remote sensing. To study the microwave emissivity of city, some ‘pure’ city pixels were selected according to IGBP classification data, which was defined the fraction cover of city is larger than 85%. The city emissivity was calculated using AMSR-E L2A brightness temperature and GLDAS land surface temperature data at different frequencies and polarizations over 2008 in China. Then the seasonal variation was analyzed along the year. Finally, the characteristic of city emissivity were compared with some meteorological data, seeking the relationship between city emissivity and climatic factors. The results have shown that the emissivity of city was different for different frequencies. It increased with the frequency becoming higher. The emissivity fluctuated along with seasons changing. According to comparison with meteorological data, the city emissivity is influenced by precipitation and snow. The precipitation and snow are important factors that impacted the city’s emissivity in summer and winter respectively. [1] Yongpan Zhang, Lingmei Jiang, Baoyu Qiu, Shengli Wu, Jiancheng Shi, Lixin Zhang. Study of microwave emissivity characteristics over different land cover types. Spectroscopy and Spectral Analysis. 2010,6:1446-145.

Zhang, T.; Zhang, L.; Jiang, L.; Li, Y.

2010-12-01

22

Study of the microwave emissivity characteristics over Gobi Desert  

NASA Astrophysics Data System (ADS)

The microwave emissivity represents the capacity of the thermal radiation of the surface, and it is the significant parameter for understanding the geophysical processes such as surface energy budget and surface radiation. Different land covers have different emissivity properties, and the Gobi Desert in Central Asia seriously impact the sandstorms occur and develop in China, because of its special geographical environment and surface soil characteristics. In this study half-month averaged microwave emissivity from March 2003 to February 2004 over the Gobi Desert has been estimated. Emissivities in this area at different frequencies, polarization and their seasonal variations are discussed respectively. The results showed that emissivity polarization difference decrease as the frequency increases, and the polarization difference is large (0.03-0.127). The H polarization emissivity increases with increasing frequency, but the V-polarized microwave emissivity is reduced with increasing frequency because of the body scattering. In winter, emissivity decreases sharply in snow covered area, especially for higher frequencies (such as 89GHz). In addition, we compared emissivity with MODIS NDVI data at the same time in the Gobi Desert, and the results indicate that NDVI derived the good negative correlation with microwave emissivity polarization difference at 37GHz.

Yubao, Qiu; Lijuan, Shi; Wenbo, Wu

2014-03-01

23

Microwave anomalous propagation (AP) measurement over Akure South-Western Nigeria  

NASA Astrophysics Data System (ADS)

Anomalous propagation (Anaprop) of microwave radiation is known to be caused by several meteorological conditions. In this study, radio refractive index and modified refractivity gradient were computed using the results of measurements of atmospheric pressure, temperature and relative humidity made in Akure (7.15°N, 5.12°E), South Western Nigeria using Davis 6162 Wireless Vantage Pro2 weather stations (Integrated Sensor Suite, ISS) positioned at five different height levels beginning from the ground surface and at intervals of 50 m from the ground to a height of 200 m on a tower/mast owned by the Nigeria Television Authority (NTA) located at Iju in Akure north local government area of Ondo state but which is no longer being used. The study utilized one year of data measured between January and December 2008. From the results, the modified refractivity was calculated and found to increase with increasing altitude. The values were observed to be generally high during the rainy periods and generally low during the dry periods. The study also revealed that for microwave propagation in this geographic zone, the propagation condition is mostly super-refractive.

Adediji, A. T.; Ajewole, M. O.

2010-04-01

24

Enhancement of LIBS emission using antenna-coupled microwave.  

PubMed

Intensified microwave coupled by a loop antenna (diameter of 3 mm) has been employed to enhance the laser-induced breakdown spectroscopy (LIBS) emission. In this method, a laser plasma was induced on Gd?O? sample at a reduced pressure by focusing a pulsed Nd:YAG laser (532 nm, 10 ns, 5 mJ) at a local point, at which electromagnetic field was produced by introducing microwave radiation using loop antenna. The plasma emission was significantly enhanced by absorbing the microwave radiation, resulting in high-temperature plasma and long-lifetime plasma emission. By using this method, the enhancement of Gd lines was up to 32 times, depending upon the emission lines observed. A linear calibration curve of Ca contained in the Gd?O? sample was made. The detection limit of Ca was approximately 2 mg/kg. This present method is very useful for identification of trace elements in nuclear fuel and radioactive materials. PMID:24514526

Khumaeni, Ali; Motonobu, Tampo; Katsuaki, Akaoka; Masabumi, Miyabe; Ikuo, Wakaida

2013-12-01

25

Aircraft measurements of microwave emission from Arctic Sea Ice  

NASA Technical Reports Server (NTRS)

Measurements of the microwave emission from Arctic Sea ice were made with aircraft at 8 wavelengths ranging from 0.510 cm to 2.81 cm. The expected contrast in emissivities between ice and water was observed at all wavelengths. Distributions of sea ice and open water were mapped from altitudes up to 11 km in the presence of dense cloud cover. Different forms of ice also exhibited strong contrasts in emissivity. Emissivity differences of up to 0.2 were observed between two types of ice at 0.811 cm wavelength. The higher emissivity ice type is tentatively identified as having been formed more recently than the lower emissivity ice.

Wilheit, T. T.; Blinn, J.; Campbell, W. J.; Edgerton, A. T.; Nordberg, W.

1971-01-01

26

Reactive Oxygen Emission from Microwave Discharge Plasmas  

NASA Astrophysics Data System (ADS)

Metastable oxygen atoms and molecules have received increased interest because of their function in surface modification, bio-decontamination and many other industrial applications, in addition to the role in the upper atmospheric layer chemistry. We review work on production and detection of metastable oxygen and we describe our experiments, including the development of techniques for measurement of metastable molecular oxygen. We show that either metastable oxygen molecules or metastable oxygen atoms can be produced in large quantities in electrical discharges, carefully tailored to promote the required kinetics. Although the two species may coexist, colder discharge regimes favor production of molecules, while at higher temperature conditions atomic oxygen prevails. We found that microwave cavity discharges in He/O2 mixtures favor molecular production, but that an arc-seeded microwave torch in air shows preference of atomic production. Result on the specific yield of molecular oxygen in the microwave cavity discharge shows qualitative agreement with the models.

Popovi?, S.; Raškovi?, M.; Kuo, S. P.; Vuškovi?, L.

2007-10-01

27

Fine and ultrafine particle emissions from microwave popcorn.  

PubMed

This study characterized fine (PM2.5 ) and ultrafine particle (UFP, diameter < 100 nm) emissions from microwave popcorn and analyzed influential factors. Each pre-packed popcorn bag was cooked in a microwave oven enclosed in a stainless steel chamber for 3 min. The number concentration and size distribution of UFPs and PM2.5 mass concentration were measured inside the chamber repeatedly for five different flavors under four increasing power settings using either the foil-lined original package or a brown paper bag. UFPs and PM2.5 generated by microwaving popcorn were 150-560 and 350-800 times higher than the emissions from microwaving water, respectively. About 90% of the total particles emitted were in the ultrafine size range. The emitted PM concentrations varied significantly with flavor. Replacing the foil-lined original package with a brown paper bag significantly reduced the peak concentration by 24-87% for total particle number and 36-70% for PM2.5 . A positive relationship was observed between both UFP number and PM2.5 mass and power setting. The emission rates of microwave popcorn ranged from 1.9 × 10(10) to 8.0 × 10(10) No./min for total particle number and from 134 to 249 ?g/min for PM2.5 . PMID:24106981

Zhang, Q; Avalos, J; Zhu, Y

2014-04-01

28

SPINNING DUST EMISSION: EFFECTS OF IRREGULAR GRAIN SHAPE, TRANSIENT HEATING, AND COMPARISON WITH WILKINSON MICROWAVE ANISOTROPY PROBE RESULTS  

SciTech Connect

Planck is expected to answer crucial questions on the early universe, but it also provides further understanding on anomalous microwave emission. Electric dipole emission from spinning dust grains continues to be the favored interpretation of anomalous microwave emission. In this paper, we present a method to calculate the rotational emission from small grains of irregular shape with moments of inertia I{sub 1} {>=} I{sub 2} {>=} I{sub 3}. We show that a torque-free rotating irregular grain with a given angular momentum radiates at multiple frequency modes. The resulting spinning dust spectrum has peak frequency and emissivity increasing with the degree of grain shape irregularity, which is defined by I{sub 1}:I{sub 2}:I{sub 3}. We discuss how the orientation of the dipole moment {mu} in body coordinates affects the spinning dust spectrum for different regimes of internal thermal fluctuations. We show that the spinning dust emissivity for the case of strong thermal fluctuations is less sensitive to the orientation of {mu} than in the case of weak thermal fluctuations. We calculate spinning dust spectra for a range of gas density and dipole moment. The effect of compressible turbulence on spinning dust emission is investigated. We show that the emission in a turbulent medium increases by a factor from 1.2 to 1.4 relative to that in a uniform medium, as the sonic Mach number M{sub s} increases from 2 to 7. Finally, spinning dust parameters are constrained by fitting our improved model to five-year Wilkinson Microwave Anisotropy Probe cross-correlation foreground spectra, for both the H{alpha}-correlated and 100-{mu}m-correlated emission spectra.

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)

2011-11-10

29

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

30

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

Microsoft Academic Search

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 variabilities of soil moisture on a global basis. Unfortunately, terrestrial microwave emission is also sensitive to water within the

Brian K. Hornbuckle; Anthony W. England; Martha C. Anderson

2007-01-01

31

Error Sources in Remote Sensing of Microwave Land Surface Emissivity  

Microsoft Academic Search

The retrieval of land surface emissivity from satellite passive microwave measurements often requires the knowledge of various radiative components (e.g., atmospheric upwelling and downwelling radiation) contributed to the measurements. Under a cloud-free condition, atmospheric and surface radiative compo- nents can be derived from atmospheric temperature and water vapor, and surface temperature data. Thus, the quality of these auxiliary data sets

Hu Yang; Fuzhong Weng

2011-01-01

32

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

33

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

34

Characterization of Errors in a Coupled Snow Hydrology–Microwave Emission Model  

Microsoft Academic Search

Traditional approaches to the direct estimation of snow properties from passive microwave remote sensing have been plagued by limitations such as the tendency of estimates to saturate for moderately deep snowpacks and the effects of mixed land cover within remotely sensed pixels. An alternative approach is to assimilate satellite microwave emission observations directly, which requires embedding an accurate microwave emissions

Konstantinos M. Andreadis; Ding Liang; Leung Tsang; Dennis P. Lettenmaier; Edward G. Josberger

2008-01-01

35

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

36

Experimental study of the microwave emission from electrons in air  

E-print Network

We searched for the emission of microwave radiation in the Ku band generated by a 95 keV electron beam in air. We unequivocally detected the radiation, and measured its yield and angular dependence. Both the emitted power and its angular pattern are well described by a model, where microwave photons are generated via bremsstrahlung in the free-electron atomic-nucleus collisions, during the slowdown of the electrons. As a consequence, the radiation is not isotropic but peaked in the forward direction. The emission yield scales proportionally with the number of electrons. This contrasts a previous claim that the yield scales with the number squared, due to coherence. With a Monte Carlo simulation we extrapolate our results to the Ultra High Energy Cosmic Ray energy range.

E. Conti; G. Collazuol; G. Sartori

2014-08-25

37

Experimental study of the microwave emission from electrons in air  

E-print Network

We searched for the emission of microwave radiation in the Ku band generated by a 95 keV electron beam in air. We unequivocally detected the radiation, and measured its yield and angular dependence. Both the emitted power and its angular pattern are well described by a model, where microwave photons are generated via bremsstrahlung in the free-electron atomic-nucleus collisions, during the slowdown of the electrons. As a consequence, the radiation is not isotropic but peaked in the forward direction. The emission yield scales proportionally with the number of electrons. This contrasts a previous claim that the yield scales with the number squared, due to coherence. With a Monte Carlo simulation we extrapolate our results to the Ultra High Energy Cosmic Ray energy range.

Conti, E; Sartori, G

2014-01-01

38

Experimental study of the microwave emission from electrons in air  

NASA Astrophysics Data System (ADS)

We searched for the emission of microwave radiation in the Ku band generated by a 95 keV electron beam in air. We unequivocally detected the radiation, and measured its yield and angular dependence. Both the emitted power and its angular pattern are well described by a model, where microwave photons are generated via bremsstrahlung in the free-electron atomic-nucleus collisions, during the slowdown of the electrons. As a consequence, the radiation is not isotropic but peaked in the forward direction. The emission yield scales proportionally with the number of electrons. This contrasts a previous claim that the yield scales with the number squared, due to coherence. With a Monte Carlo simulation we extrapolate our results to the ultra high energy cosmic ray energy range.

Conti, E.; Collazuol, G.; Sartori, G.

2014-10-01

39

Microwave emission and scattering from vegetated terrain  

NASA Technical Reports Server (NTRS)

Models are developed for the apparent temperature and backscattering coefficient of vegetated terrain to illustrate the effects of vegetation on the sensitivity of these parameters to variations of soil moisture. Three types of terrain are simulated for both the passive and the active case: a uniform canopy over a smooth surface, plant rows on a smooth surface, and plant rows on a rough surface. In each case the canopy is defined by its overall dimensions and by its electric permittivity, which is determined from Weiner model for dielectric mixture. Emission and scattering from both the soil and the canopy are considered, but atmospheric effects are neglected. Calculated data indicate that the sensitivity of the apparent temperature and backscattering coefficient to variations of soil moisture, decreases as the amount of vegetation increases. It is shown that the same effect results from increasing signal frequency or angle of incidence.

Sibley, T. G.

1973-01-01

40

Observations of Microwave Continuum Emission from Air Shower Plasmas  

E-print Network

We investigate a possible new technique for microwave measurements of ultra-high energy cosmic ray (UHECR) 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 AWA (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 SLAC (Stanford Linear Accelerator Center) in summer of 2004 confirmed the major features of the previous AWA observations with better precision and made additional measurements relevant to the calorimetric capabilities of the method. Prompted by these results we built a prototype detector using satellite television technology, and have made measurements indicating possible 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 of UHECR, which are limited to dark, clear nights. By contrast, decimeter microwave observations can be made both night and day, in clear or cloudy weather, or even in the presence of moderate precipitation.

P. W. Gorham; N. G. Lehtinen; G. S. Varner; J. J. Beatty; A. Connolly; P. Chen; M. E. Conde; W. Gai; C. Hast; C. L. Hebert; C. Miki; R. Konecny; J. Kowalski; J. Ng; J. G. Power; K. Reil; D. Saltzberg; B. T. Stokes; D. Walz

2007-05-17

41

Microwave Absorption, Emission and Scattering: Trace Gases and Meteorological Parameters  

NASA Astrophysics Data System (ADS)

Space-borne remote sensing techniques are widely used today to investigate the atmosphere, both by operational and experimental instruments on a large number of satellites. Sensors operating in the microwave range, defined as being wavelengths from 10 to 0.1 cm, frequency 3-300 GHz (microwaves also comprise sub-millimetre waves or frequencies up to 3,000 GHz) of the electromagnetic spectrum were among the first instruments used for this purpose from the ground and on board air- and space-borne platforms. Those instruments measured the thermal emission from a molecular resonance or used the absorption and scattering properties of water droplets or ice crystals to obtain information on atmospheric parameters and composition.

Kunzi, Klaus; Bauer, Peter; Eresmaa, Reima; Eriksson, Patrick; Healy, Sean B.; Mugnai, Alberto; Livesey, Nathaniel; Prigent, Catherine; Smith, Eric A.; Stephens, Graeme

42

Global Microwave Emission Depth Analyses from AMSR-E, SSMI, and MODIS  

Microsoft Academic Search

A global analysis of microwave emission depth signatures shows that the characteristic temporal behaviors associated with subsurface emission in sand deserts carry over to arid and semi-arid regions worldwide. Previous work showed that the greatly reduced diurnal range of SSM\\/I brightness temperatures compared to skin temperatures in deserts could be explained by microwave effective emission depths that depended on soil

John F. Galantowicz; Jean-Luc Moncet; Pan Liang; Alan E. Lipton

2008-01-01

43

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

44

Investigating Non-icy Material Fraction from Microwave Emission  

NASA Astrophysics Data System (ADS)

We will present calibrated, high- 2000 km) and low- 8000 km) resolution maps of Saturn’s rings at 2.2-cm wavelength acquired by the Cassini radar radiometer. Microwave emission is the ideal waveband for studying the scattering properties of cm-scale ring particles and for constraining the thermal emission from (possibly buried) non-icy ring contaminants, which, unlike water ice, behave as blackbodies at cm-wavelengths. While occultation observations are necessarily restricted to near-forward scattered light, scattered emission from Saturn (an extended source) can be viewed at a wide range of geometries. In order to successfully remove energy contributed by radar’s extensive side-lobes, we use an iterative self-calibration process. The current calibration reaches an RMS residual of 0.18 K 2% ring brightness temperature). The observed microwave brightness temperature of Saturn’s rings is dominated by scattered Saturn emission and intrinsic thermal emission from the rings. We adopted a Monte Carlo multiple scattering model for the A, B and C rings that treats non-icy materials as inclusions in icy particles. Our results predict that the non-icy component of the C ring, assuming that contaminants behave with the dielectric properties of acidic rock, has a baseline volume fraction of ~2% throughout the entire C Ring with humps at the center and inner region that reach a maximum of ~7%. The implications of these results for the origin and evolution of the Saturn’s rings will be discussed. Furthermore, in optically thick B ring, the scattering properties of ring particles are altered by the closely packed effect. We employed a near-field Fresnel diffraction pattern for near field scattering events. Details on this near-field effect will be discussed.

Zhang, Zhimeng; Hayes, Alex; Janssen, Mike; Nicholson, Phillip; Cuzzi, Jeff; Dunn, David; de Pater, Imke

2014-11-01

45

Radical Emissions and Anomalous Reverse Flames Appearing in Upward-Increasing Magnetic Fields  

Microsoft Academic Search

Upward-increasing magnetic fields of lower intensities increased flame dimensions and liberations of carbons, and decreased radical emissions, temperatures and a bluing tendency of the flame. These phenomena were opposite to those occurring in the upward-decreasing magnetic fields. The upward-increasing magnetic fields of stronger intensities caused an anomalous inverse burning, where the positions of the blue and the yellow-orange regions are

Takashi Aoki

1990-01-01

46

The retrievals of effective grain size and snow water equivalent from variationally-retrieved microwave surface emissivities  

Microsoft Academic Search

This study introduces a new technique for the estimation of the snow effective grain size and water equivalent based on the microwave surface emissivity spectra retrieved from a one-dimensional variational retrieval system and a microwave snow emissivity model. The microwave emissivity model is derived analytically from the dense media radiative transfer theory. The model snow physical parameters include the effective

C. Kongoli; S.-A. Boukabara; F. Weng

2008-01-01

47

Effects of soil tillage on the microwave emission of soils  

NASA Technical Reports Server (NTRS)

In order to understand the interactions of soil properties and microwave emission better, a series of field experiments were conducted in 1984. Small plots were measured with a truck-mounted passive microwave radiometer operating at 1.4 GHz. These data were collected concurrent with ground observations of soil moisture and bulk density. Treatment effects studied included different soil moisture contents and bulk densities. Evaluations of the data have shown that commonly used models of the dielectric properties of wet soils do not explain the observations obtained in these experiments. This conclusion was based on the fact that the roughness parameters determined through optimization were significantly larger than those observed in similar investigations. These discrepancies are most likely due to the soil structure. Commonly used models assume a homogeneous three phase mixture of soil solids, air and water. Under tilled conditions the soil is actually a two phase mixture of aggregates and voids. Appropriate dielectric models for this tilled condition were evaluated and found to explain the observations. These results indicate that previous conclusions concerning the effects of surface roughness in tilled fields may be incorrect, and they may explain some of the inconsistencies encountered in roughness modeling.

Jackson, T. J.; Koopman, G. J.; Oneill, P. E.; Wang, J. R.

1985-01-01

48

On the Extended Emission of the Anomalous X-ray Pulsar IE 1547.0-5408  

NASA Technical Reports Server (NTRS)

We present an analysis of the extended emission around the anomalous X-ray pulsar IE 1547.0-5408 using four XMM-Newton observations taken with the source in varying states of outburst as well as in quiescence. We find that the extended emission flux is highly variable and strongly correlated with the flux of the magnetar. Based on this result, as well as on spectral and energetic considerations, we conclude that the extended emission is dominated by a dust-scattering halo and not a pulsar wind nebula (P-VVN), as has been previously argued. We obtain an upper limit on the 2-10 keV flux of a possible PWN of 4.7 x 10(exp -14) erg/s/sq cm, three times less than the previously claimed value, implying an efficiency for conversion of spin-down energy into nebular luminosity of <9 x 10(exp -4) .

Olausen, S. A.; Kaspi, V. M.; Ng, C. -Y.; Zhu, W. W.; Gavriil, F. P.; Woods, P. M.

2012-01-01

49

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

50

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...

51

Characterization of Errors in a Coupled Snow HydrologyMicrowave Emission Model KONSTANTINOS M. ANDREADIS  

E-print Network

cycle, through its effects on water storage and the land surface energy balance, has long beenCharacterization of Errors in a Coupled Snow Hydrology­Microwave Emission Model KONSTANTINOS M to the direct estimation of snow properties from passive microwave remote sensing have been plagued

Tsang, Leung

52

Microwave backscattering and emission model for grass canopies  

NASA Technical Reports Server (NTRS)

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, Sasan S.; Levine, David M.; Lang, Roger H.

1994-01-01

53

An SSM/I radiometer simulator for studies of microwave emission from soil. [Special Sensor Microwave/Imager  

NASA Technical Reports Server (NTRS)

A ground-based simulator of the defense meterological satellite program special sensor microwave/imager (DMSP SSM/I) is described, and its integration with micrometeorological instrumentation for an investigation of microwave emission from moist and frozen soils is discussed. The simulator consists of three single polarization radiometers which are capable of both Dicke radiometer and total power radiometer modes of operation. The radiometers are designed for untended operation through a local computer and a daily telephone link to a laboratory. The functional characteristics of the radiometers are described, together with their field deployment configuration and an example of performance parameters.

Galantowicz, J. F.; England, A. W.

1992-01-01

54

Neutral beam model for the anomalous gamma-ray emission component in GRB 941017  

E-print Network

Gonz\\'alez et al. (2003) have reported the discovery of an anomalous radiation component from ~ 1 -- 200 MeV in GRB 941017. This component varies independently of and contains > 3 times the energy found in the prompt ~ 50 keV -- 1 MeV radiation component that is well described by the relativistic synchrotron-shock model. Acceleration of hadrons to very high energies can give rise to two additional emission components, one produced inside the GRB blast wave and one associated with an escaping beam of ultra-high energy (UHE; > 10^{14} eV) neutrons, gamma rays, and neutrinos. The first component extending to ~ 100 MeV is from a pair-photon cascade induced by photomeson processes with the internal synchrotron photons coincident with the prompt radiation. The outflowing UHE neutral beam can undergo further interactions with external photons from the backscattered photon field to produce a beam of hyper-relativistic electrons that lose most of their energy during a fraction of a gyroperiod in the assumed Gauss-strength magnetic fields of the circumburst medium. The synchrotron radiation of these electrons has a spectrum with vF_v index equal to +1 that can explain the anomalous component in GRB 941017. This interpretation of the spectrum of GRB 941017 requires a high baryon load of the accelerated particles in GRB blast waves. It implies that most of the radiation associated with the anomalous component is released at > 500 MeV, suitable for observations with GLAST, and with a comparable energy fluence in ~100 TeV neutrinos that could be detected with a km-scale neutrino telescope like IceCube.

C. D. Dermer; A. Atoyan

2004-01-08

55

Optical properties of metals: Infrared emissivity in the anomalous skin effect spectral region  

NASA Astrophysics Data System (ADS)

When the penetration depth of an electromagnetic wave in a metal is similar to the mean free path of the conduction electrons, the Drude classical theory is no longer satisfied and the skin effect becomes anomalous. Physical parameters of this theory for twelve metals were calculated and analyzed. The theory predicts an emissivity peak ?peak at room temperature in the mid-infrared for smooth surface metals that moves towards larger wavelengths as temperature decreases. Furthermore, the theory states that ?peak increases with the emission angle but its position, ?peak, is constant. Copper directional emissivity measurements as well as emissivity obtained using optical constants data confirm the predictions of the theory. Considering the relationship between the specularity parameter p and the sample roughness, it is concluded that p is not the simple parameter it is usually assumed to be. Quantitative comparison between experimental data and theoretical predictions shows that the specularity parameter can be equal to one for roughness values larger than those predicted. An exhaustive analysis of the experimental optical parameters shows signs of a reflectance broad peak in Cu, Al, Au, and Mo around the wavelength predicted by the theory for p = 1.

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

2014-09-01

56

The electron injection spectrum determined by anomalous excesses in cosmic ray, gamma ray, and microwave data  

SciTech Connect

Recent cosmic ray, gamma ray, and microwave signals observed by Fermi, PAMELA, and WMAP indicate an unexpected primary source of e{sup +}e{sup -} at 10-1000 GeV. We fit these data to 'standard backgrounds' plus a new source, assumed to be a separable function of position and energy. For the spatial part, we consider three cases: annihilating dark matter, decaying dark matter, and pulsars. In each case, we use GALPROP to inject energy in log-spaced energy bins and compute the expected cosmic ray and photon signals for each bin. We then fit a linear combination of energy bins, plus backgrounds, to the data. We use a nonparametric fit, with no prior constraints on the spectrum except smoothness and non-negativity. In addition, we consider arbitrary modifications to the energy spectrum of the ordinary primary source function, fixing its spatial part, finding this alone to be inadequate to explain the PAMELA or WMAP signals. We explore variations in the fits due to choice of magnetic field, primary electron injection index, spatial profiles, propagation parameters, and fit regularization method. Dark matter annihilation fits well, where our fit finds a mass of {approx}1 TeV and a boost factor times energy fraction of {approx}70. While it is possible for dark matter decay and pulsars to fit the data, unconventionally high magnetic fields and radiation densities are required near the Galactic center to counter the relative shallowness of the assumed spatial profiles. We also fit to linear combinations of these three scenarios, though the fit is much less constrained.

Lin Tongyan; Finkbeiner, Douglas P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States); Physics Department, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138 (United States); Dobler, Gregory [Kavli Institute for Theoretical Physics, Kohn Hall, Santa Barbara, California 93106 (United States)

2010-07-15

57

Land surface characterization using microwave emissivity derived from multi-satellite radiometric observations  

NASA Astrophysics Data System (ADS)

The microwave land surface emissivity has been estimated on a global scale from SSM/I brightness temperature observations at 19, 37, and 85 GHz for both horizontal (H) and vertical (V) polarizations using an in-house developed microwave Radiative Transfer computation code. The retrieval technique has been validated by comparing the retrieved emissivity with TELSEM emissivity climatology and with theoretical models. The variability in microwave emissivity with respect to geographical patterns, vegetation cover, flooded areas, and snow cover for different seasons (and interannual) have been studied. The standard deviation of the monthly mean emissivity has been found to be < 0.015 for all surface classes, except for coastal and desert regions (< 0.02). Attempt has also been made to explore the potential of microwave emissivity data for delineating flood-inundated regions as well as studying different arid and desert regions on global basis. The microwave emissivity derived from TRMM/TMI at 19.35 and 85.5 GHz with both H and V polarisations, are used for deriving the flood index parameter. The study has also been applied to the data (limited) rom MADRAS payload aboard Megha-Tropiques satellite. The estimated emissivities contribute to the data set which can be directly used for data assimilation, as an a priori input for the retrieval of atmospheric parameters over the continental region, for delineation of the flood extent, and for the characterization of arid and desert regions. The methodology and the results will be presented in detail.

Raju C, Suresh; Krishna Moorthy, K.; Antony, Tinu; Mathew, Nizy

58

On Hadronic Models for the Anomalous $?$-ray Emission Component in GRB 941017  

E-print Network

Gonz\\'alez et al. (2003) have reported the discovery of an anomalous radiation component from ~ 1 -- 200 MeV in GRB 941017. This component varies independently of and contains >~ 3 times the energy found in the prompt ~ 50 keV -- 1 MeV radiation component that is well described by the relativistic synchrotron-shock model. Acceleration of hadrons to very high energies by GRBs could give rise to a separate emission component. Two models, both involving acceleration of ultra-high energy cosmic rays with subsequent photomeson interactions, are considered. The first involves a pair-photon cascade initiated by photohadronic processes in the GRB blast wave. Calculations indicate that the cascade produces a spectrum that is too soft to explain the observations. A second model is proposed where photopion interactions in the GRB blast-wave shell give rise to an escaping collimated neutron beam. The outflowing neutrons undergo further photopion interactions to produce a beam of hyper-relativistic electrons that can lose most of their energy during a fraction of a gyroperiod in the Gauss-strength magnetic fields found in the circumburst medium. This secondary electron beam produces a hard synchrotron radiation spectrum that could explain the anomalous component in GRB 941017.

C. D. Dermer; A. Atoyan

2003-12-09

59

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.

60

Modeling the Non-Thermal X-ray Tail Emission of Anomalous X-ray Pulsars  

E-print Network

The paradigm for Anomalous X-ray Pulsars (AXPs) has evolved recently with the discovery by INTEGRAL and RXTE of flat, hard X-ray components in three AXPs. These non-thermal spectral components differ dramatically from the steeper quasi-power-law tails seen in the classic X-ray band in these sources, and can naturally be attributed to activity in the magnetosphere. Resonant, magnetic Compton upscattering is a candidate mechanism for generating this new component, since it is very efficient in the strong fields present near AXP surfaces. In this paper, results from an inner magnetospheric model for upscattering of surface thermal X-rays in AXPs are presented, using a kinetic equation formalism and employing a QED magnetic scattering cross section. Characteristically flat and strongly-polarized emission spectra are produced by non-thermal electrons injected in the emission region. Spectral results depend strongly on the observer's orientation and the magnetospheric locale of the scattering, which couple directly to the angular distributions of photons sampled. Constraints imposed by the Comptel upper bounds for these AXPs are mentioned.

Matthew G. Baring; Alice K. Harding

2008-04-02

61

Modeling the Non-Thermal X-ray Tail Emission of Anomalous X-ray Pulsars  

NASA Astrophysics Data System (ADS)

The paradigm for Anomalous X-ray Pulsars (AXPs) has evolved recently with the discovery by INTEGRAL and RXTE of flat, hard X-ray components in three AXPs. These non-thermal spectral components differ dramatically from the steeper quasi-power-law tails seen in the classic X-ray band in these sources, and can naturally be attributed to activity in the magnetosphere. Resonant, magnetic Compton upscattering is a candidate mechanism for generating this new component, since it is very efficient in the strong fields present near AXP surfaces. In this paper, results from an inner magnetospheric model for upscattering of surface thermal X-rays in AXPs are presented, using a kinetic equation formalism and employing a QED magnetic scattering cross section. Characteristically flat and strongly-polarized emission spectra are produced by non-thermal electrons injected in the emission region. Spectral results depend strongly on the observer's orientation and the magnetospheric locale of the scattering, which couple directly to the angular distributions of photons sampled. Constraints imposed by the Comptel upper bounds for these AXPs are mentioned.

Baring, Matthew G.; Harding, Alice K.

2008-01-01

62

On-line preconcentration with activated carbon for microwave plasma torch atomic emission spectrometry  

Microsoft Academic Search

This paper presents a method whereby trace elements are adsorbed in NH4Cl?NH3 medium on activated carbon and then determined by microwave plasma torch atomic emission spectrometry (MPT-AES). The working conditions (including microwave forward power, gas flow rate, NH3?NH4Cl concentration in the sample solution, HCl concentration in the eluant, sample introduction rate and preconcentration time) were investigated in detail. The effects

Hanqi Zhang; Xianglin Yuan; Xiaojun Zhao; Qinhan Jin

1997-01-01

63

Anomalous temperature dependence of field emission from W18O49 nanowires caused by surface states and field penetration  

NASA Astrophysics Data System (ADS)

In this paper, we studied how field emission from thermally evaporated W18O49 nanowires depended on temperature. As the temperature changed from 300 K to 723 K, we found anomalous changes in emission current. Below an applied field of ˜12.5 V ?m-1, the emission current tended to increase with rising temperature, while above 12.5 V ?m-1 the current depended less on temperature in the range of 573-723 K. Furthermore, at high temperatures, we found the Fowler-Nordheim plots of these nanowires to be nonlinear. We believe that the anomalous behavior is associated with surface states at low fields and field penetration at high fields.

Chen, W. Q.; Zhan, R. Z.; Deng, S. Z.; Xu, N. S.; Chen, Jun

2014-10-01

64

Jet-Shocked H2 and CO in the Anomalous Arms of Molecular Hydrogen Emission Galaxy NGC 4258  

E-print Network

We present a Spitzer Infrared Spectrograph (IRS) map of H2 emission from the nearby galaxy NGC 4258 (Messier 106). The H2 emission comes from 9.4E6 Msun of warm molecular hydrogen heated to 240-1040 K in the inner anomalous arms, a signature of jet interaction with the galaxy disk. The spectrum is that of a molecular hydrogen emission galaxy (MOHEG), with a large ratio of H2 over 7.7 micron PAH emission (0.37), characteristic of shocked molecular gas. We find close spatial correspondence between the H2 and CO emission from the anomalous arms. Our estimate of cold molecular gas mass based on CO emission is 10 times greater than our estimate of 1.0E8 Msun based on dust emission. We suggest that the X(CO) value is 10 times lower than the Milky Way value because of high kinetic temperature and enhanced turbulence. The H2 disk has been overrun and is being shocked by the jet cocoon, and much of the gas originally in the disk has been ejected into the galaxy halo in an X-ray-hot outflow. We measure a modest star fo...

Ogle, Patrick M; Appleton, Philip N

2014-01-01

65

Jet-shocked H2 and CO in the Anomalous Arms of Molecular Hydrogen Emission Galaxy NGC 4258  

NASA Astrophysics Data System (ADS)

We present a Spitzer Infrared Spectrograph map of H2 emission from the nearby galaxy NGC 4258 (Messier 106). The H2 emission comes from 9.4 ± 0.4 × 106 M ? of warm molecular hydrogen heated to 240-1040 K in the inner anomalous arms, a signature of jet interaction with the galaxy disk. The spectrum is that of a molecular hydrogen emission galaxy (MOHEG), with a large ratio of H2 over 7.7 ?m polycyclic aromatic hydrocarbon emission (0.37), characteristic of shocked molecular gas. We find close spatial correspondence between the H2 and CO emission from the anomalous arms. Our estimate of cold molecular gas mass based on CO emission is 10 times greater than our estimate of 1.0 × 108 M ? based on dust emission. We suggest that the X CO value is 10 times lower than the Milky Way value because of high kinetic temperature and enhanced turbulence. The H2 disk has been overrun and is being shocked by the jet cocoon, and much of the gas originally in the disk has been ejected into the galaxy halo in an X-ray hot outflow. We measure a modest star formation rate of 0.08 M ? yr-1 in the central 3.4 kpc2 that is consistent with the remaining gas surface density.

Ogle, P. M.; Lanz, L.; Appleton, P. N.

2014-06-01

66

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

USGS Publications Warehouse

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. ?? 1985 Birkha??user Verlag.

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

1985-01-01

67

Anomalous three-dimensional refraction in the microwave region by ultra-thin high efficiency metalens with phase discontinuities in orthogonal directions  

NASA Astrophysics Data System (ADS)

An ultrathin flat metalens that experimentally realizes three-dimensional microwave manipulation has been demonstrated as able to approach the theoretical limit of cross-polarization (cross-pol) conversion efficiency of the transmission, as predicted by Monticone et al (2013 Phys. Rev. Lett. 110 203903). The helicity-dependent phase change is introduced to the transmission and can be engineered by assembling the spatial orientation of each Pancharatnam–Berry phase element. By realizing the constant phase gradients in orthogonal directions, an anomalous non-coplanar refraction is unanimously demonstrated in the three-dimensional space under the circular-polarized incidence, and the refraction angle is well predicted with the generalized Snell’s law, derived with phase gradients in orthogonal directions. More importantly, the maximum conversion efficiency of the cross-pol transmission is as high as 24%, which approaches the upper-bound of the theoretical limit. The proposed metalens has only a single layer as thin as 0.001 ?, which massively reduces the thickness of the microwave lens along the wave propagation direction. With the great improvements in efficiency and the thickness reduction, as well as the excellent non-coplanar refraction, our design provides a promising approach to miniaturize, planarize and integrate multiple microwave components.

Zhang, Kuang; Ding, Xumin; Zhang, Liang; Wu, Qun

2014-10-01

68

Dynamics of anomalous temperature-induced emission shift in MOCVD-grown (Al,In)GaN thin films  

SciTech Connect

The authors present a comprehensive study of the optical characteristics of (Al, In)GaN epilayers measured by photoluminescence (PL), integrated PL intensity, and time-resolved PL spectroscopy. For not only InGaN, but also AlGaN epilayers with large Al content, they observed an anomalous PL temperature dependence: (i) an S-shaped PL peak energy shift (decrease-increase-decrease) and (ii) an inverted S-shaped full width at half maximum (FWHM) change (increase-decrease-increase) with increasing temperature. Based on time-resolved PL, the S shape (inverted S shape) of the PL peak position (FWHM) as a function of temperature, and the much smaller PL intensity decrease in the temperature range showing the anomalous emission behavior, the authors conclude that strong localization of carriers occurs in InGaN and even in AlGaN with rather high Al content. They observed that the following increase with increasing Al content in AlGaN epilayers: (i) a Stokes shift between the PL peak energy and the absorption edge, (ii) a redshift of the emission with decay time, (iii) the deviations of the PL peak energy, FWHM, and PL intensity from their typical temperature dependence, and (iv) the corresponding temperature range of the anomalous emission behavior. This indicates that the band-gap fluctuation responsible for these characteristics is due to energy tail states caused by non-random inhomogeneous alloy potential variations enhanced with increasing Al content.

Cho, Y.H.; Gainer, G.H.; Lam, J.B.; Song, J.J.; Yang, W.; Jhe, W.

2000-07-01

69

The field emission of vacuum filtered graphene films reduced by microwave  

NASA Astrophysics Data System (ADS)

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), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectroscopy (UV-vis) measurements proved that the graphene prepared by microwave has nearly the same reduction level as that prepared by hydrazine. The results of field emission testing demonstrated that graphene films reduced by microwave are more suitable as field emitters than those reduced by hydrazine, which pave a way to mass-produce low-cost graphene emitter for field emission applications.

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

2011-04-01

70

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

71

Clouds and rain effects on perturbed water surface microwave reflection and emission at 37 GHz  

Microsoft Academic Search

In this paper the structure and operational features of Ka-band, combined scatterometric-radiometric system and the results of spatio-temporally collocated measurements of perturbed pool water surface microwave reflective (radar backscattering coefficient) and emissive (brightness temperature) characteristics angular dependences at ~37GHz are presented, curried out under clear air, heavy clouds and rain conditions.

Melanya L. Grigoryan; Artashes K. Arakelyan; Astghik K. Hambaryan; Vanik V. Karyan; Gagik G. Hovhannisyan; Arsen A. Arakelyan; Sargis A. Darbinyan

2010-01-01

72

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

73

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

74

Microwave millisecond spike emission and its associated phenomena during the impulsive phase of large flares  

NASA Technical Reports Server (NTRS)

A tentative model is proposed to account for some features of the microwave millisecond spike emission and its links with the physical processes of associated phenomena during the impulsive phase of large flares by comparing the optical, radio, and X-ray observations on May 16, 1981 to those on October 12, 1981.

Li, Chunsheng; Jiang, Shuying; Li, Hongwei; Fu, Qi-Jun

1986-01-01

75

Spectral characteristics of the microwave emission from a wind-driven foam-covered sea  

Microsoft Academic Search

Aircraft observations of the microwave emission from the Bering Sea show that the spectral character of brightness temperature variation with wind speed in a fully developed sea is due to a combination of surface roughness and a surface layer with varying dielectric constant over a physical depth of a few millimeters. The varying dielectric layer is identified with cusps formed

William J. Webster; Thomas T. Wilheit; Duncan B. Ross; Per Gloersen

1976-01-01

76

Spectral Characteristics of the Microwave Emission From a Wind-Driven Foam-Covered Sea  

Microsoft Academic Search

Aircraft observations of the microwave emission from the Bering Sea show that the spectral character of brightness temperature variation with wind speed in a fully developed sea is due to a combination of surface roughness and a surface layer with varying dielectric constant over a physical depth of a few millimeters. The varying dielectric layer is identified with cusps formed

William J. Webster; Thomas T. Wilheit; Duncan B. Ross; Per Gloersen

1976-01-01

77

Emission of non-thermal microwave radiation by a Martian dust storm  

Microsoft Academic Search

We report evidence for the emission of non-thermal microwave radiation by a deep Martian dust storm. The observations were made using an innovative detector that can discriminate between radiation of thermal and non-thermal origin by measuring the high order moments of its electric field strength. Measurements with this detector, installed in a 34 m radio telescope of the Deep Space

Christopher Ruf; Nilton O. Renno; Jasper F. Kok; Etienne Bandelier; Michael J. Sander; Steven Gross; Lyle Skjerve; Bruce Cantor

2009-01-01

78

Acoustic emission feedback control for control of boiling in a microwave oven  

DOEpatents

An acoustic emission based feedback system for controlling the boiling level of a liquid medium in a microwave oven is provided. The acoustic emissions from the medium correlated with surface boiling is used to generate a feedback control signal proportional to the level of boiling of the medium. This signal is applied to a power controller to automatically and continuoulsly vary the power applied to the oven to control the boiling at a selected level.

White, Terry L. (Oak Ridge, TN)

1991-01-01

79

Fullerenes as carriers of extinction, diffuse interstellar bands and anomalous microwave emission  

Microsoft Academic Search

According to semiempirical models, photoabsorption by fullerenes (single and multishell) could explain the shape, width and peak energy of the most prominent feature of the interstellar absorption, the UV bump at 2175 Å. Other weaker transitions are predicted in the optical and near-infrared providing a potential explanation for diffuse interstellar bands. In particular, we find that several fullerenes could contribute

Susana Iglesias-Groth

2008-01-01

80

Study on microwave emission mechanisms on the basis of hypervelocity impact experiments on various target plates  

NASA Astrophysics Data System (ADS)

It was formerly confirmed by experiment that hypervelocity impacts on aluminum plates cause microwave emission. In this study, we have carried out experiments in order to clarify the mechanism of the emission. The microwave is detected by heterodyne detection scheme at 22 and 2 GHz with an intermediate frequency bandwidth of 500 and 120 MHz, respectively. A nylon projectile is accelerated using a light-gas gun to impact a target. First, aluminum plates with ten different thicknesses ranging from 1 to 40 mm were used as a target, and microwave signals were detected. The experimental results are statistically analyzed assuming a Gaussian distribution of the emitted power. The standard deviation of pulse voltage is calculated to show the existence of two kinds of signals: sharp pulse and thermal noise. It is shown that the emitted energy and the dispersion have a relation with the extent of the target destruction. Next, nylon projectiles are impacted on different metals such as aluminum, iron, and copper. These results suggest that microcracks are essential to microwave emission. Finally, in order to clarify the mechanism of charging and discharging across the microcracks, the experimental results are compared with this model for the following factors: (1) the thermally excited electrons and the emitted power, and (2) the bond dissociation energy of target material and emitted power. The analytical results suggest that electrons are excited thermally and by transition from a crystalline state to an atomic state.

Ohnishi, H.; Chiba, S.; Soma, E.; Ishii, K.; Maki, K.; Takano, T.; Hasegawa, S.

2007-06-01

81

Rock fraction effects on the interpretation of microwave emission from soils  

NASA Technical Reports Server (NTRS)

The effects of rock fraction on the relationship between microwave emission and surface soil moisture were investigated through a combination of laboratory dielectric measurements and field observation of emissivity. Field measurements were conducted which included soils with and without rocks. Microwave brightness temperature was measured at L and C band using a truck-mounted radiometer. Dielectric measurements were made at L band. Field observations of emissivity showed that the presence of rocks decreases the range of the measurements. At 21 cm this decrease was relatively small; however, at 6 cm almost all sensitivity to soil moisture was eliminated by the presence of 35 percent rocks. Comparisons between observed and predicted data showed that the effects of rock fraction are not significant in estimating the sample soil moisture for the tested conditions.

Jackson, Thomas J.; Kostov, Kosta; Saatchi, Sasan S.

1991-01-01

82

WMAP Microwave Emission Interpreted as Dark Matter Annihilation in the Inner Galaxy  

E-print Network

Excess microwave emission observed in the inner Galaxy (inner ~1 kpc) is consistent with synchrotron emission from highly relativistic electron-positron pairs produced by dark matter particle annihilation. More conventional sources for this emission, such as free-free (thermal bremsstrahlung), thermal dust, spinning dust, and the softer Galactic synchrotron traced by low-frequency surveys, have been ruled out. The total power observed in the range 23 =2x10^{-26} cm^3/s, and an 1/r dark matter mass profile truncated in the inner Galaxy, and find this scenario to be consistent with current data.

Douglas P. Finkbeiner

2004-09-02

83

Spectral characteristics of the microwave emission from a wind-driven foam-covered sea  

NASA Technical Reports Server (NTRS)

Aircraft observations of the microwave emission from the wind-driven foam-covered Bering Sea substantiate earlier results and show that the combination of surface roughness and white water yields a significant microwave brightness temperature dependence on wind speed over a wide range of microwave wavelengths, with a decreasing dependence for wavelengths above 6 cm. The spectral characteristic of brightness temperature as a function of wind speed is consistent with a foam model in which the bubbles give rise to a cusped surface between the foam and the sea. In the fetch-limited situation the contribution of the wave structure at the surface appears to increase as the foam coverage decreases. Although the data show that the thin streaks are the most important part of the white water signature, there is some evidence for the contribution of whitecaps.

Webster, W. J., Jr.; Wilheit, T. T.; Gloersen, P.; Ross, D. B.

1976-01-01

84

Behaviour of a desolvation system based on microwave radiation heating for use in inductively coupled plasma atomic emission spectrometry  

Microsoft Academic Search

The present paper describes the preliminary results obtained with a desolvation system for inductively coupled plasma atomic emission spectrometry that incorporates a heating unit based on microwave (MW) radiation. This system has been called Microwave Desolvation System (MWDS). The results have proved that MW radiation can be considered as a good choice for aerosol heating in a sample introduction system.

Luis Gras; Juan Mora; José L. Todolí; Vicente Hernandis; Antonio Canals

1997-01-01

85

Analysis of polarized microwave emission of Flare-Productive Active Region 9415  

E-print Network

The results of the microwave observations of the Sun made with the RATAN-600 have shown the existence of many types of spectral peculiarities in polarized emission of active regions, which produce powerful flares. These phenomena happen at microwaves and reflect inhomogeneous structure of magnetic field in magnetospheres of flaring active regions in wide range of heights above the photosphere. In this presentation we demonstrate an analysis of the AR 9415 during all the period of its passage across the solar disk. Results of the study point out to existence of different scenarios of circular polarization variations in the radio wave band. Here, we separated the phenomenon of the cyclotron emission passage through the quasi-transverse magnetic field (QT-region) and several effects connected with flare activity of active region. New observational data are presented and compared with the data of several observatories: SSRT, NoRH, MDI SOHO, GOES and MEES. The preliminary interpretation of the phenomena are given.

V. M. Bogod; G. B. Gelfreikh; F. Ch. Drago; V. P. Maximov; A. Nindos; T. I. Kaltman; B. I. Ryabov; S. Kh. Tokhchukova

2003-09-16

86

Measurement of hot-electron production and microwave emission by laser-irradiated CH targets  

Microsoft Academic Search

An experimental study was conducted on hot-electron production and microwave emission by laser irradiated targets. The laser was a neodymium glass laser (1.06-micron wavelength). Typically the laser beam consisted of a weak 3 mJ repulse followed by a strong 30 J main pulse 8ns later. Both pulses had a temporal duration of 150 psec and were focused to a 30-micron

J. E. Heidrich; S. K. Ault; H. A. Koehler; S. M. Pollaine; V. W. Slivinsky; R. A. Zacharias; J. D. Kilkenny

1984-01-01

87

Manifestations of Energetic Electrons with Anisotropic Distributions in Solar Flares. II. Gyrosynchrotron Microwave Emission  

Microsoft Academic Search

We investigate the spectra and polarization of the gyrosynchrotron microwave (MW) emission generated by anisotropic electron beams in the solar corona. The electron distributions are selected from the steady propagation\\/precipitation model of beam electrons obtained from the time-dependent solutions of the Fokker-Planck equation taking into account particle anisotropic precipitation into a converging magnetic tube while losing energy in collisions and

Alexey A. Kuznetsov; Valentina V. Zharkova

2010-01-01

88

The influence of spatial variability of polar firn on microwave emission  

NASA Astrophysics Data System (ADS)

Precise measurements of snow structural parameters and stratigraphy are essential to understand and model the radiative properties of the snow cover. However, most snow measurements are limited in spatial resolution and by extensive measurement times, which particularly constrains their applicability in harsh polar environments. For this reason, we developed a statistical model to derive three major snow structural parameters, density, correlation length and specific surface area solely from a portable, high-resolution penetrometer. We demonstrate the potential of the method by a 25 m long and 1.1 m deep transect through Antarctic firn at Kohnen Station, Antarctica, which reveals the stratigraphic features of the firn clearly. Based on these data, we run the Microwave Emission Model of Layered Snowpacks (MEMLS) and analyze the influence of the spatial variability of the firn around Kohnen Station on the microwave emission of the snowpack. We discuss the potential and limitations of the method and highlight the need for spatially distributed, quantitative measurements for modeling the microwave emission from polar snow and firn.

Proksch, Martin; Löwe, Henning; Weissbach, Stefanie; Schneebeli, Martin

2014-05-01

89

Simulations of gyrosynchrotron microwave emission from an oscillating magnetic loop  

NASA Astrophysics Data System (ADS)

Radio observations of solar flares often reveal various periodic or quasi-periodic oscillations. Most likely, these oscillations are caused by MHD oscillations of flaring loops which modulate the radio emission via variations of the magnetic field and electron concentration. We perform numerical simulations of gyrosynchrotron radiation from a toroidal-shaped magnetic loop containing sausage-mode MHD oscillations. Different parameters of the loop and MHD oscillations and different loop orientations are considered. The simulation results are compared with the observations of the Nobeyama Radioheliograph.

Kuznetsov, Alexey; Reznikova, Veronika; Van Doorsselaere, Tom; Antolin, Patrick

90

Anomalous Arms  

NASA Technical Reports Server (NTRS)

In this composite image of spiral galaxy M106 (NGC 4258), optical data from the Digitized Sky Survey is shown as yellow, radio data from the Very Large Array appears as purple, X-ray data from Chandra is coded blue, and infrared data from the Spitzer Space Telescope appears red. Two anomalous arms, which aren't visible at optical wavelengths, appear as purple and blue emission.

2007-01-01

91

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

92

Assessment of the consistency among global microwave land surface emissivity products  

NASA Astrophysics Data System (ADS)

The goal of this work is to inter-compare a number of global land surface emissivity products over various land-cover conditions to assess their consistency. Ultimately, the discrepancies between the studied emissivity products will help interpreting the divergences among numerical weather prediction models in which land emissivity is a key surface boundary parameter. The intercompared retrieved land emissivity products were generated over five-year period (2003-2007) using observations from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E), Special Sensor Microwave Imager (SSM/I), The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and Windsat. First, all products were reprocessed in the same projection and spatial resolution as they were generated from sensors with various configurations. Then, the mean value and standard deviations of monthly emissivity values were calculated for each product to assess the spatial distribution of the consistencies/inconsistencies among the products across the globe. The emissivity values from four products were also compared to soil moisture estimates and satellite-based vegetation index to assess their sensitivities to the changes in land surface conditions. Results show that systematic differences among products exist and variation of emissivities at each product has similar frequency dependency at any land cover type. Monthly means of emissivity values from AMSR-E in the vertical and horizontal polarizations seem to be systematically lower across various land cover condition which may be attributed to the 1.30 a.m./p.m. overpass time of the sensor and possibly a residual skin temperature effect in the product. The standard deviation of the analysed products was the lowest (less than 0.01) in rain forest regions for all products and the highest in northern latitudes, above 0.04 for AMSR-E and SSM/I and around 0.03 for WindSat. Despite differences in absolute emissivity estimates, all products were similarly sensitive to changes in soil moisture and vegetation. The correlation between the emissivity polarization differences and NDVI values showed similar spatial distribution across the products with values close to the unit except over densely vegetated and desert areas.

Norouzi, H.; Temimi, M.; Prigent, C.; Turk, J.; Khanbilvardi, R.; Tian, Y.; Furuzawa, F.; Masunaga, H.

2014-09-01

93

Derivation of an Analytical Approximation of the Spectrum of Spinning Dust Emission  

E-print Network

An analytical function for the spectrum of spinning dust emission is presented. It is derived through the application of careful approximations, with each step tested against numerical calculations. This approach ensures accuracy while providing an intuitive picture of the physics. The final result may be useful for fitting of anomalous microwave emission observations, as is demonstrated by a comparison with the Planck observations of the Perseus Molecular Cloud. It is hoped that this will lead to a broader consideration of the spinning dust model when interpreting microwave continuum observations, and that it will provide a standard framework for interpreting and comparing the variety of anomalous microwave emission observations.

Stevenson, Matthew

2014-01-01

94

Microwave emissivity of freshwater ice, Part II: Modelling the Great Bear and Great Slave Lakes  

E-print Network

Lake ice within three Advanced Microwave Scanning Radiometer on EOS (AMSR-E) pixels over the Great Bear and Great Slave Lakes have been simulated with the Canadian Lake Ice Model (CLIMo). The resulting thicknesses and temperatures were fed to a radiative transfer-based ice emissivity model and compared to the satellite measurements at three frequencies---6.925 GHz, 10.65 GHz and 18.7 GHz. Excluding the melt season, the model was found to have strong predictive power, returning a correlation of 0.926 and a residual of 0.78 Kelvin at 18 GHz, vertical polarization. Discrepencies at melt season are thought to be caused by the presence of dirt in the snow cover which makes the microwave signature more like soil rather than ice. Except at 18 GHz, all results showed significant bias compared to measured values. Further work needs to be done to determine the source of this bias.

Mills, Peter

2012-01-01

95

Strong anomalous emission from He-like and H-like Ne in short-pulse laser-driven plasmas  

SciTech Connect

We observe strong emission from the 1{ital s}{sup 2}{endash}1{ital snp} Rydberg series in He-like Ne and from the Lyman-{alpha} transition in H-like Ne. These emissions are observed when 1.05-{mu}m light in a 600-fs laser pulse is focused into the dense, localized output of a pulsed supersonic nozzle. The maximum focal irradiance of our laser was measured at full power in vacuum to be 1.1{times}10{sup 18} W/cm{sup 2}. Although emissions from lower charge states such as Ne{sup 6+} and Ne{sup 7+} closely follow rates predicted by tunneling theory, emissions from Ne{sup 8+} and Ne{sup 9+} are observed at irradiances 2 orders of magnitude below tunneling theory estimates. We discuss the origins of these anomalously high charge states and the implications to the development of short-pulse, ultrahigh-brightness x-ray sources. {copyright} {ital 1996 Optical Society of America.}

Crane, J.K.; Nguyen, H.; Wilks, S.C.; Ditmire, T.; Coverdale, C.A.; Glover, T.E.; Perry, M.D.; Zakharenkov, Y. [Lawrence Livermore National Laboratory, L-493, P.O. Box 808, Livermore, California 94550 (United States)

1996-01-01

96

ON THE EXTENDED EMISSION AROUND THE ANOMALOUS X-RAY PULSAR 1E 1547.0-5408  

SciTech Connect

We present an analysis of the extended emission around the anomalous X-ray pulsar 1E 1547.0-5408 using four XMM-Newton observations taken with the source in varying states of outburst as well as in quiescence. We find that the extended emission flux is highly variable and strongly correlated with the flux of the magnetar. Based on this result, as well as on spectral and energetic considerations, we conclude that the extended emission is dominated by a dust-scattering halo and not a pulsar wind nebula (PWN), as has been previously argued. We obtain an upper limit on the 2-10 keV flux of a possible PWN of 4.7 Multiplication-Sign 10{sup -14} erg s{sup -1} cm{sup -2}, three times less than the previously claimed value, implying an efficiency for conversion of spin-down energy into nebular luminosity of <9 Multiplication-Sign 10{sup -4} (assuming a distance of 4 kpc). We do, however, find strong evidence for X-ray emission from the supernova remnant shell surrounding the pulsar, as previously reported.

Olausen, S. A.; Kaspi, V. M.; Ng, C.-Y.; Zhu, W. W.; Dib, R. [Department of Physics, Rutherford Physics Building, McGill University, 3600 University Street, Montreal, Quebec H3A 2T8 (Canada); Gavriil, F. P. [NASA Goddard Space Flight Center, Astrophysics Science Division, Code 662, Greenbelt, MD 20771 (United States); Woods, P. M. [Dynetics, Inc., 1000 Explorer Boulevard, Huntsville, AL 35806 (United States)

2011-11-20

97

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

98

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

99

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

100

Effect of Microwave and He-Ne Laser on Enzyme Activity and Biophoton Emission of Isatis indigotica Fort  

Microsoft Academic Search

The seed embryos of Isatis indigotica Fort were exposed to He-Ne laser (5.23 mW\\/mm2, radiated for 5 min) and microwave (1.26 mW\\/mm2, radiated for 8 s) irradiation to determine the effects of microwave and He-Ne laser pretreatment on enzyme activities, and biophoton emission of cotyledon. Then: (i) changes in the activities of enzymes in I. indigotica cotyledon (such as amylase,

Yi-Ping CHEN; Yong-Jun LIU; Xun-Ling WANG; Zhao-Yu REN; Ming YUE

2005-01-01

101

TEMPORAL AND SPATIAL ANALYSES OF SPECTRAL INDICES OF NONTHERMAL EMISSIONS DERIVED FROM HARD X-RAYS AND MICROWAVES  

SciTech Connect

We studied electron spectral indices of nonthermal emissions seen in hard X-rays (HXRs) and microwaves. We analyzed 12 flares observed by the Hard X-Ray Telescope aboard Yohkoh, Nobeyama Radio Polarimeters, and the Nobeyama Radioheliograph (NoRH), and compared the spectral indices derived from total fluxes of HXRs and microwaves. Except for four events, which have very soft HXR spectra suffering from the thermal component, these flares show a gap {Delta}{delta} between the electron spectral indices derived from HXRs {delta} {sub X} and those from microwaves {delta}{sub {mu}} ({Delta}{delta} = {delta} {sub X} - {delta}{sub {mu}}) of about 1.6. Furthermore, from the start to the peak times of the HXR bursts, the time profiles of the HXR spectral index {delta} {sub X} evolve synchronously with those of the microwave spectral index {delta}{sub {mu}}, keeping the constant gap. We also examined the spatially resolved distribution of the microwave spectral index by using NoRH data. The microwave spectral index {delta}{sub {mu}} tends to be larger, which means a softer spectrum, at HXR footpoint sources with stronger magnetic field than that at the loop tops. These results suggest that the electron spectra are bent at around several hundreds of keV, and become harder at the higher energy range that contributes the microwave gyrosynchrotron emission.

Asai, Ayumi [Unit of Synergetic Studies for Space, Kyoto University, Yamashina, Kyoto, 607-8471 (Japan)] [Unit of Synergetic Studies for Space, Kyoto University, Yamashina, Kyoto, 607-8471 (Japan); Kiyohara, Junko; Takasaki, Hiroyuki [Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto, 607-8471 (Japan)] [Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto, 607-8471 (Japan); Narukage, Noriyuki [Institute of Space and Astronomical Science, Japan Aerospace Exploration Agency, Chuo, Sagamihara, Kanagawa, 229-8510 (Japan)] [Institute of Space and Astronomical Science, Japan Aerospace Exploration Agency, Chuo, Sagamihara, Kanagawa, 229-8510 (Japan); Yokoyama, Takaaki [Department of Earth and Planetary Science, University of Tokyo, Hongo, Bunkyo, Tokyo, 113-0033 (Japan)] [Department of Earth and Planetary Science, University of Tokyo, Hongo, Bunkyo, Tokyo, 113-0033 (Japan); Masuda, Satoshi [Solar-Terrestrial Environment Laboratory, Nagoya University, Chikusa, Nagoya, Aichi, 464-8601 (Japan)] [Solar-Terrestrial Environment Laboratory, Nagoya University, Chikusa, Nagoya, Aichi, 464-8601 (Japan); Shimojo, Masumi [National Astronomical Observatory of Japan, Mitaka, Tokyo, 181-8588 (Japan)] [National Astronomical Observatory of Japan, Mitaka, Tokyo, 181-8588 (Japan); Nakajima, Hiroshi, E-mail: asai@kwasan.kyoto-u.ac.jp [Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Minamisaku, Nagano, 384-1305 (Japan)] [Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Minamisaku, Nagano, 384-1305 (Japan)

2013-02-15

102

Constraints on the Emission and Viewing Geometry of the Transient Anomalous X-Ray Pulsar XTE J1810-197  

NASA Astrophysics Data System (ADS)

The temporal decay of the flux components of the transient anomalous X-ray pulsar XTE J1810-197 following its 2002 outburst presents a unique opportunity to probe the emission geometry of a magnetar. Toward this goal, we model the magnitude of the pulsar's modulation in narrow spectral bands over time. Following previous work, we assume that the postoutburst flux is produced in two distinct thermal components arising from a hot spot and a warm concentric ring. We include general relativistic effects on the blackbody spectra due to gravitational redshift and light bending near the stellar surface, which strongly depend on radius. This affects the model fits for the temperature and size of the emission regions. For the hot spot, the observed temporal and energy-dependent pulse modulation is found to require an anisotropic, pencil-beamed radiation pattern. We are able to constrain an allowed range for the angles that the line of sight (?) and the hot spot pole (?) make with respect to the spin axis. Within errors, this is defined by the locus of points in the ?-? plane that lie along the line [?+?(R)[?+?(R)~const, where ?(R) is a function of the radius R of the star. For a canonical value of R=12 km, the viewing parameters range from ?=?=37deg to (?,?)=(85deg,15deg). We discuss our results in the context of magnetar emission models.

Perna, Rosalba; Gotthelf, E. V.

2008-07-01

103

Emission spectra from direct current and microwave powered Hg lamps at very high pressure  

NASA Astrophysics Data System (ADS)

Discharge lamps containing mercury at pressures above 100 bar are commercially used in data projectors and television projector systems. Due to their small size, these lamps are difficult to investigate experimentally, but spectral measurements, combined with radiation transport calculations, have provided useful information on the visible spectrum. However, classical spectral line broadening theory is inadequate to describe the UV portion of the spectrum, so self-consistent modelling of these discharges is not possible at present. This paper discusses the differences between discharges containing electrodes and discharges sustained by a microwave (mw) electromagnetic field, on the basis of the experimentally measured temperature profile in an electroded discharge, and a temperature profile computed from a 1D power balance model for a microwave discharge. A model based on the ray-tracing method is employed to simulate the radiation transport in these lamps. The model has been validated by comparing the emission spectrum from dc discharge lamps with those obtained experimentally. The output flux, luminous flux, luminous efficacy, the correlated colour temperature, the chromaticity coordinates and photometric curves of the lamp were then obtained. These results were also compared with those of a theoretically calculated temperature profile for the same lamp, excited by microwave power in the TM010 mode.

Hamady, M.; Lister, G. G.; Stafford, L.

2013-11-01

104

Crane et al. Vol. 13, No. 1/January 1996/J. Opt. Soc. Am. B 89 Strong anomalous emission from He-like and  

E-print Network

Crane et al. Vol. 13, No. 1/January 1996/J. Opt. Soc. Am. B 89 Strong anomalous emission from He-like and H-like Ne in short-pulse laser-driven plasmas J. K. Crane, H. Nguyen, S. C. Wilks, T. Ditmire, C. A

Ditmire, Todd

105

Analytical Retrieval of Global Land Surface Emissivity Maps at AMSR-E passive microwave frequencies  

NASA Astrophysics Data System (ADS)

Land emissivity is a crucial boundary condition in Numerical Weather Prediction (NWP) modeling. Land emissivity is also a key indicator of land surface and subsurface properties. The objective of this study, supported by NOAA-NESDIS, is to develop global land emissivity maps using AMSR-E passive microwave measurements along with several ancillary data. The International Satellite Cloud Climatology Project (ISCCP) database has been used to obtain several inputs for the proposed approach such as land surface temperature, cloud mask and atmosphere profile. The Community Radiative Transfer Model (CRTM) has been used to estimate upwelling and downwelling atmospheric contributions. Although it is well known that correction of the atmospheric effect on brightness temperature is required at higher frequencies (over 19 GHz), our preliminary results have shown that a correction at 10.7 GHz is also necessary over specific areas. The proposed approach is based on three main steps. First, all necessary data have been collected and processed. Second, a global cloud free composite of AMSR-E data and corresponding ancillary images is created. Finally, monthly composting of emissivity maps has been performed. AMSR-E frequencies at 6.9, 10.7, 18.7, 36.5 and 89.0 GHz have been used to retrieve the emissivity. Water vapor information obtained from ISCCP (TOVS data) was used to calculate upwelling, downwelling temperatures and atmospheric transmission in order to assess the consistency of those derived from the CRTM model. The frequent land surface temperature (LST) determination (8 times a day) in the ISCCP database has allowed us to assess the diurnal cycle effect on emissivity retrieval. Differences in magnitude and phase between thermal temperature and low frequencies microwave brightness temperature have been noticed. These differences seem to vary in space and time. They also depend on soil texture and thermal inertia. The proposed methodology accounts for these factors and resultant differences in phase and magnitude between LST and microwave brightness temperature. Additional factors such as topography and vegetation cover are under investigation. In addition, the potential of extrapolating the obtained land emissivity maps to different window and sounding channels has been also investigated in this study. The extrapolation of obtained emissivities to different incident angles is also under investigation. Land emissivity maps have been developed at different AMSR-E frequencies. Obtained product has been validated and compared to global land use distribution. Moreover, global soil moisture AMSR-E product maps have been also used to assess to the spatial distribution of the emissivity. Moreover, obtained emissivity maps seem to be consistent with landuse/land cover maps. They also agree well with land emissivity maps obtained from the ISCCP database and developed using SSM/I observations (for frequencies over 19 GHz).

Norouzi, H.; Temimi, M.; Khanbilvardi, R.

2009-12-01

106

Preliminary analysis of Skylab RADSCAT results over the ocean. [using radar backscatter and microwave emission  

NASA Technical Reports Server (NTRS)

Preliminary observations at 13.9 GHz of the radar backscatter and microwave emission from the sea were analyzed using data obtained by the radiometer scatterometer on Skylab. Results indicate approximately a square-law relationship between differential scattering coefficient and windspeed at angles of 40 deg to 50 deg, after correction for directional effect, over a range from about 4 up to about 25 meters/sec. The brightness temperature response was also observed, and considerable success was achieved in correcting it for atmospheric attenuation and emission. Measurements were made in June, 1973, over Hurricane Ava off the west coast of Mexico and over relatively calm conditions in the Gulf of Mexico and Caribbean Sea.

Moore, R. K.; Claassen, J. D.; Young, J. D.; Pierson, W. J., Jr.; Cardone, V. J.

1974-01-01

107

Microwave plasma CVD-grown graphene-CNT hybrids for enhanced electron field emission applications  

NASA Astrophysics Data System (ADS)

The growth and electron emission characteristics were investigated from a hybrid structure of multiwalled carbon nanotubes (MWCNTs) and multilayer layer graphene (MLG) deposited on silicon substrate coated with iron catalyst and an interlayer of aluminium. The hybrid structures were synthesized in a two-step process by microwave plasma-enhanced chemical vapour deposition technique. The formation of MWCNTs takes place by absorption and precipitation of carbon radicals into the catalyst particles. Thereafter, ample carbon forms MLG on tip of the MWCNTs resulting in a MLG-MWCNTs hybrid nanostructure. MLG was observed to grow branching out of the tips and sidewalls of the MWCNTs and is expected to attach by Van der Walls bonds. Transmission electron microscopy and micro-Raman spectroscopy confirmed the crystalline nature of the hybrid structures. Electron emission studies were carried out using a diode-type field emission setup. The enhancement factor was found to be ~3,500 for bare MWCNTs, ~4,070 to ~5,000 for hybrid structures and ~6,500 for N-doped MLG-MWCNTs hybrid structures. Modification in the defects structure and enhancement of emission sites are suggested to be responsible for the increase of the field emission characteristics.

Kaushik, Vishakha; Shukla, A. K.; Vankar, V. D.

2014-08-01

108

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

109

On the wavelength dependence of apparent emissivity of asteroid microwave emissions - Ceres and Vesta  

NASA Technical Reports Server (NTRS)

Observations of Ceres and Vesta demonstrate the need for modifying the physical parameters of the standard model procedure in treating single-wavelength observations. It is suggested that simultaneous IR and cm-wavelength data should be used in order to determine such properties as the surface dielectric characteristics, layer depth, and radio emissivity. If using the standard model, an emissivity of 0.8 should be adopted for wavelengths of longer than 1 cm.

Webster, William J., Jr.; Johnston, Kenneth J.

1989-01-01

110

Anomalous enhanced emission from PbS quantum dots on a photonic-crystal microcavity  

SciTech Connect

We report up to 75 times enhancement in emission from lithographically produced photonic crystals with postprocessing close-packed colloidal quantum-dot incorporation. In our analysis, we use the emission from a close-packed free-standing film as a reference. After discounting the angular redistribution effect, our analysis shows that the observed enhancement is larger than the combined effects of Purcell enhancement and dielectric enhancement with the microscopic local field. The additional enhancement mechanisms, which are consistent with all our observations, are thought to be spectral diffusion mediated by phonons and local polarization fluctuations that allow off-resonant excitons to emit at the cavity wavelengths.

Luk, Ting Shan; Xiong, Shisheng; Chow, Weng W.; Miao, Xiaoyu; Subramania, Ganesh; Resnick, Paul J.; Fischer, Arthur J.; Brinker, Jeffrey C.

2011-01-01

111

Comparative study of x ray and microwave emissions during solar flares  

NASA Technical Reports Server (NTRS)

The work supported by the grant consisted of two projects. The first project involved making detailed case studies of two flares using SMM data in conjunction with ground based observations. The first flare occurred at 1454 UT on June 20, 1989 and involved the eruption of a prominence near the limb. In the study we used data from many wavelength regimes including the radio, H-alpha, hard X-rays, and soft X-rays. We used a full gyrosynchrotron code to model the apparent presence of a 1.4 GHz source early in the flare that was in the form of a large coronal loop. The model results lead us to conclude that the initial acceleration occurs in small, dense loops which also produced the flare's hard X-ray emission. We also found evidence that a source at 1.4 GHz later in the event was due to second harmonic plasma emission. This source was adjacent to a leg of the prominence and comes from a dense column of material in the magnetic structure supporting the prominence. Finally, we investigated a source of microwaves and soft X-rays, occurring approximately 10 min after the hard X-ray peak, and calculate a lower limit for the density of the source. The second flare that was studied occurred at 2156 UT on June 20, 1989 and was observed with the VLA and the Owens Valley Radio Observatory (OVRO) Frequency Agile Array. We have developed a gyrosynchrotron model of the sources at flare peak using a new gyrosynchrotron approximation which is valid at very low harmonics of the gyrofrequency. We found that the accelerated particle densities of the sources decreased much more with radius from the source center than had been supposed in previous work, while the magnetic field varied less. We also used the available data to analyze a highly polarized source which appeared late in the flare. The second project involved compiling a statistical base for the relative timing of the hard X-ray peak, the turbulent and blue-shift velocities inferred from soft X-ray line emissions observed by SMM and the microwave peak as determined from ground-based observations. This timing was then used to aid the testing of newly developed global models for flares that incorporate the global magnetic topology as well as the electron dynamics that are responsible for the hard X-rays and microwaves.

Winglee, Robert M.

1993-01-01

112

L-Band H Polarized Microwave Emission During the Corn Growth Cycle  

NASA Technical Reports Server (NTRS)

Hourly L-band (1.4 GHz) horizontally (H) polarized brightness temperatures (T(sub B))'s measured during five episodes (more than two days of continuous measurements) of the 2002 corn growth cycle are analyzed. These T(sub B)'s measurements were acquired as a part of a combined active/passive microwave field campaign, and were obtained at five incidence and three azimuth angles relative to the row direction. In support of this microwave data collection, intensive ground sampling took place once a week. Moreover, the interpretation of the hourly T(sub B)'s could also rely on the data obtained using the various automated instruments installed in the same field. In this paper, the soil moisture and temperature measured at fixed time intervals have been employed as input for the tau-omega model to reproduce the hourly T(sub B). Through the calibration of the vegetation and surface roughness parameterizations, the impact of the vegetation morphological changes on the microwave emission and the dependence of the soil surface roughness parameter, h(sub r), on soil moisture are investigated. This analysis demonstrates that the b parameter, appearing in the representation of the canopy opacity, has an angular dependence that varies throughout the growing period and also that the parameter hr increases as the soil dries in a portion of the dry-down cycle. The angular dependence of the b parameter imposes the largest uncertainty on T(sub B) simulations near senescence as the response of b to the incidence is also affected by the crop row orientation. On the other hand, the incorporation of a soil moisture dependent h(sub r) parameterization was responsible for the largest error reduction of T(sub B) simulations in the early growth cycle.

Joseph, A. T.; va der Velde, R.; O'Neill, P. E.; Kim, E.; Lang, R. H.; Gish, T.

2012-01-01

113

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

114

Iapetus’ near surface thermal emission modeled and constrained using Cassini RADAR Radiometer microwave observations  

NASA Astrophysics Data System (ADS)

Since its arrival at Saturn, the Cassini spacecraft has had only a few opportunities to observe Iapetus, Saturn’s most distant regular satellite. These observations were all made from long ranges (>100,000 km) except on September 10, 2007, during Cassini orbit 49, when the spacecraft encountered the two-toned moon during its closest flyby so far. In this pass it collected spatially resolved data on the object’s leading side, mainly over the equatorial dark terrains of Cassini Regio (CR). In this paper, we examine the radiometry data acquired by the Cassini RADAR during both this close-targeted flyby (referred to as IA49-3) and the distant Iapetus observations. In the RADAR’s passive mode, the receiver functions as a radiometer to record the thermal emission from planetary surfaces at a wavelength of 2.2-cm. On the cold icy surfaces of Saturn’s moons, the measured brightness temperatures depend both on the microwave emissivity and the physical temperature profile below the surface down to a depth that is likely to be tens of centimeters or even a few meters. Combined with the concurrent active data, passive measurements can shed light on the composition, structure and thermal properties of planetary regoliths and thus on the processes from which they have formed and evolved. The model we propose for Iapetus’ microwave thermal emission is fitted to the IA49-3 observations and reveals that the thermal inertias sensed by the Cassini Radiometer over both CR and the bright mid-to-high latitude terrains, namely Ronceveaux Terra (RT) in the North and Saragossa Terra (ST) in the South, significantly exceed those measured by Cassini’s CIRS (Composite Infrared Spectrometer), which is sensitive to much smaller depths, generally the first few millimeters of the surface. This implies that the subsurface of Iapetus sensed at 2.2-cm wavelength is more consolidated than the uppermost layers of the surface. In the case of CR, a thermal inertia of at least 50 J m-2 K-1 s-1/2, and most probably >200 J m-2 K-1 s-1/2 is inferred. This suggests a gradient in density with depth or, more likely, that the Radiometer has probed the icy substrate underlying the dark layer. Furthermore, the measured thermal emission is found to arise from the upper few meters of the subsurface, which points to tholins, rather than iron oxide compounds, as the primary contaminants of the dark material. We also find that, although there is a latitudinal decrease probably related to the thinning of the dark layer away from the Equator, the CR region exhibits a high 2.2-cm emissivity, 0.87 in average, which is close to the emissivity of Phoebe, a putative source of the dark matter. In the case of RT + ST, model fitting points to a mean thermal inertia of ?160 J m-2 K-1 s-1/2 along with the possible presence of an absorbing compound in the regolith of the bright terrains. Nevertheless, this layer is transparent enough for the Radiometer to capture the seasonal contrast between the northern and southern hemispheres. Lastly, a global decline of the microwave emissivity with latitude is revealed; it is probably indicative of a progressive increase of the water ice content in the near surface.

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

2014-10-01

115

A Temperature Dependent Correction to the Model for Microwave Excess Emissivity of the Ocean due to Surface Winds  

E-print Network

speed. This temperature dependence is a residual result of the dependence of the specular ocean surface is proportionately larger at higher temperatures. INTRODUCTION Surface winds raise the microwave emissivity- optimal performance. Sea surface temperature was restricted to be greater than 275 Kelvins. This was done

Ruf, Christopher

116

Comparison among physical process based snow models in estimating SWE and upwelling microwave emission  

NASA Astrophysics Data System (ADS)

Snowpack serves as a critical water resource and an important climate indicator. Accurately estimating snow water equivalent (SWE) and melt timing has both civil and scientific merits. Physical process based multi-layer land surface models (LSM) characterize snowpack by tracking the energy balance and mass balance in each layer. However, in terms of the number of layers used to model the snowpack stratigraphy, as well as the complexity of the simulated mass/energy exchanges in each single layer, significant variances exist among different LSMs. Previous work has largely focused on assessing the impact of layering and stratigraphy representation on mass and energy balance, with little attention paid to the implications of these factors on predicted microwave brightness temperature (Tb). In this paper, three LSMs with varying snow layer schemes: SSiB (3-layer), CoLM (5-layer), and SNOWPACK (N-layer), are coupled to the Microwave Emission from Multi-Layer Snowpacks (MEMLS) radiative transfer model (RTM) to simulate the snowpack mass/energy budgets and microwave signature over a full season. The simulations are performed at five in-situ gage locations in the Kern River Basin, Sierra Nevada, CA where it is known that large snow events occur that can be problematic to represent using a small number of snow layers. A particular emphasis is placed on assessment of the impact of layering scheme on the results. Preliminary results show that even for SSiB which has a relative simple empirical layering scheme, the modeled annual SWE could be highly correlated with the in-situ SWE (r¬2=0.91) if the precipitation bias is corrected, also, the comparison between the Tb simulated by SSiB+MEMLS and the downscaled AMSR-E Tb measurements shows a correlation coefficient of 0.94 during the snow accumulation season (Oct to Apr) if the grain growth parameters and the soil snow reflectivity is properly calibrated. Future work includes comparing SWE and Tb from all threemodels and quantitatively determining how the more complex models (SNOWPACK) could possibly further improve the Tb estimates, and how they will increase the computational loads, which are highly relevant to the ultimate goal of estimation of SWE via assimilation of multi-frequency passive microwave observations.

Li, D.; Durand, M. T.; Margulis, S. A.

2012-12-01

117

Development of a resonant-type microwave reactor and its application to the synthesis of positron emission tomography radiopharmaceuticals.  

PubMed

Microwave technology has been successfully applied to enhance the effectiveness of radiolabeling reactions. The use of a microwave as a source of heat energy can allow chemical reactions to proceed over much shorter reaction times and in higher yields than they would do under conventional thermal conditions. A microwave reactor developed by Resonance Instrument Inc. (Model 520/521) and CEM (PETWave) has been used exclusively for the synthesis of radiolabeled agents for positron emission tomography by numerous groups throughout the world. In this study, we have developed a novel resonant-type microwave reactor powered by a solid-state device and confirmed that this system can focus microwave power on a small amount of reaction solution. Furthermore, we have demonstrated the rapid and facile radiosynthesis of 16?-[(18) F]fluoroestradiol, 4-[(18) F]fluoro-N-[2-(1-methoxyphenyl)-1-piperazinyl]ethyl-N-2-pyridinylbenzamide, and N-succinimidyl 4-[(18) F]fluorobenzoate using our newly developed microwave reactor. PMID:25294422

Kimura, Hiroyuki; Yagi, Yusuke; Ohneda, Noriyuki; Odajima, Hiro; Ono, Masahiro; Saji, Hideo

2014-10-01

118

Snow stratigraphic heterogeneity within ground-based passive microwave radiometer footprints: implications for emission modelling  

NASA Astrophysics Data System (ADS)

Remote sensing of snow mass remains a challenging area of research. Scattering of electromagnetic radiation is sensitive to snow mass, but is also affected by contrasts in the dielectric properties of the snow. Although the argument that errors from simple algorithms average out at large scales has been used to justify current retrieval methods, it is not obvious why this should be the case. This hypothesis needs to be tested more rigorously. A ground-based field experiment was carried out to assess the impact of sub-footprint snow heterogeneity on microwave brightness temperature, in Churchill, Canada in winter in early 2010. Passive microwave measurements of snow were made using sled-mounted radiometers at 75cm intervals over a 5m transect. Measurements were made at horizontal and vertical polarizations at frequencies of 19 and 37 GHz. Snow beneath the radiometer footprints was subsequently excavated, creating a snow trench wall along the centrepoints of adjacent footprints. The trench wall was carefully smoothed and photographed with a near-infrared camera in order to determine the positions of stratigraphic snow layer boundaries. Three one-dimensional vertical profiles of snowpack properties (density and snow specific surface area) were taken at 75cm, 185cm and 355cm from the left hand side of the trench. These profile measurements were used to derive snow density and grain size for each of the layers identified from the NIR image. Microwave brightness temperatures for the 2-dimensional map of snow properties was simulated with the Helsinki University of Technology (HUT) model at 1cm intervals horizontally across the trench. Where each of five ice lenses was identified in the snow stratigraphy, a decrease in brightness temperature was simulated. However, the median brightness temperature simulated across the trench was substantially higher than the observations, of the order of tens of Kelvin, dependent on frequency and polarization. In order to understand and quantify possible sources of error in the simulations, a number of experiments were carried out to investigate the sensitivity of the brightness temperature to: 1) uncertainties in field observations, 2) representation of ice lenses, 3) model layering structure, and 4) near-infrared derived grain size representing snow grain size at microwave wavelengths. Field measurement error made little difference to the simulated brightness temperature, nor did the representation of ice lenses as crusts of high density snow. As the number of layers in the snow was reduced to 3, 2, or 1, the simulated brightness temperature increased slightly. However, scaling of snow grain size had a dramatic effect on the simulated brightness temperatures, reducing the median bias of the simulations to within measurement error for the statistically different brightness temperature distributions. This indicated that further investigation is required to define what is meant by the microwave grain size, and how this relates to the grain size that is used in the microwave emission model.

Sandells, M.; Rutter, N.; Derksen, C.; Langlois, A.; Lemmetyinen, J.; Montpetit, B.; Pulliainen, J. T.; Royer, A.; Toose, P.

2012-12-01

119

Numerical Model of Multiple Scattering and Emission from Layering Snowpack for Microwave Remote Sensing  

NASA Astrophysics Data System (ADS)

The vector radiative transfer (VRT) equation is an integral-deferential equation to describe multiple scattering, absorption and transmission of four Stokes parameters in random scatter media. From the integral formal solution of VRT equation, the lower order solutions, such as the first-order scattering for a layer medium or the second order scattering for a half space, can be obtained. The lower order solutions are usually good at low frequency when high-order scattering is negligible. It won't be feasible to continue iteration for obtaining high order scattering solution because too many folds integration would be involved. In the space-borne microwave remote sensing, for example, the DMSP (Defense Meterological Satellite Program) SSM/I (Special Sensor Microwave/Imager) employed seven channels of 19, 22, 37 and 85GHz. Multiple scattering from the terrain surfaces such as snowpack cannot be neglected at these channels. The discrete ordinate and eigen-analysis method has been studied to take into account for multiple scattering and applied to remote sensing of atmospheric precipitation, snowpack etc. Snowpack was modeled as a layer of dense spherical particles, and the VRT for a layer of uniformly dense spherical particles has been numerically studied by the discrete ordinate method. However, due to surface melting and refrozen crusts, the snowpack undergoes stratifying to form inhomegeneous profiles of the ice grain size, fractional volume and physical temperature etc. It becomes necessary to study multiple scattering and emission from stratified snowpack of dense ice grains. But, the discrete ordinate and eigen-analysis method cannot be simply applied to multi-layers model, because numerically solving a set of multi-equations of VRT is difficult. Stratifying the inhomogeneous media into multi-slabs and employing the first order Mueller matrix of each thin slab, this paper developed an iterative method to derive high orders scattering solutions of whole scatter media. High order scattering and emission from inhomogeneous stratifying media of dense spherical particles are numerically obtained. The brightness temperature at low frequency such as 5.3 GHz without high order scattering and at SSM/I channels with high order scattering are obtained. This approach is also compared with the conventional discrete ordinate method for an uniform layer model. Numerical simulation for inhomogeneous snowpack is also compared with the measurements of microwave remote sensing.

Jin, Y.; Liang, Z.

2002-12-01

120

Microwave and hard X-ray emissions during the impulsive phase of solar flares: Nonthermal electron spectrum and time delay  

NASA Technical Reports Server (NTRS)

On the basis of the summing-up and analysis of the observations and theories about the impulsive microwave and hard X-ray bursts, the correlations between these two kinds of emissions were investigated. It is shown that it is only possible to explain the optically-thin microwave spectrum and its relations with the hard X-ray spectrum by means of the nonthermal source model. A simple nonthermal trap model in the mildly-relativistic case can consistently explain the main characteristics of the spectrum and the relative time delays.

Gu, Ye-Ming; Li, Chung-Sheng

1986-01-01

121

Spatial Variability of Barrow-Area Shore-Fast Sea Ice and Its Relationships to Passive Microwave Emissivity  

NASA Technical Reports Server (NTRS)

Aircraft-acquired passive microwave data, laser radar height observations, RADARSAT synthetic aperture radar imagery, and in situ measurements obtained during the AMSR-Ice03 experiment are used to investigate relationships between microwave emission and ice characteristics over several space scales. The data fusion allows delineation of the shore-fast ice and pack ice in the Barrow area, AK, into several ice classes. Results show good agreement between observed and Polarimetric Scanning Radiometer (PSR)-derived snow depths over relatively smooth ice, with larger differences over ridged and rubbled ice. The PSR results are consistent with the effects on snow depth of the spatial distribution and nature of ice roughness, ridging, and other factors such as ice age. Apparent relationships exist between ice roughness and the degree of depolarization of emission at 10,19, and 37 GHz. This depolarization .would yield overestimates of total ice concentration using polarization-based algorithms, with indications of this seen when the NT-2 algorithm is applied to the PSR data. Other characteristics of the microwave data, such as effects of grounding of sea ice and large contrast between sea ice and adjacent land, are also apparent in the PSR data. Overall, the results further demonstrate the importance of macroscale ice roughness conditions such as ridging and rubbling on snow depth and microwave emissivity.

Maslanik, J. A.; Rivas, M. Belmonte; Holmgren, J.; Gasiewski, A. J.; Heinrichs, J. F.; Stroeve, J. C.; Klein, M.; Markus, T.; Perovich, D. K.; Sonntag, J. G.; Tape, K.

2006-01-01

122

Microwave emissivity of fresh water ice--Lake ice and Antarctic ice pack--Radiative transfer simulations versus satellite radiances  

E-print Network

Microwave emissivity models of sea ice are poorly validated empirically. Typical validation studies involve using averaged or stereotyped profiles of ice parameters against averaged radiance measurements. Measurement sites are rarely matched and even less often point-by-point. Because of saline content, complex permittivity of sea ice is highly variable and difficult to predict. Therefore, to check the validity of a typical, plane-parallel, radiative-transfer-based ice emissivity model, we apply it to fresh water ice instead of salt-water ice. Radiance simulations for lake ice are compared with measurements over Lake Superior from the Advanced Microwave Scanning Radiometer on EOS (AMSR-E). AMSR-E measurements are also collected over Antarctic icepack. For each pixel, a thermodynamic model is driven by four years of European Center for Medium Range Weather Forecasts (ECMWF) reanalysis data and the resulting temperature profiles used to drive the emissivity model. The results suggest that the relatively simple ...

Mills, Peter

2012-01-01

123

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

124

Electron-beam-sustained discharge revisited — light emission from combined electron beam and microwave excited argon at atmospheric pressure  

NASA Astrophysics Data System (ADS)

A novel kind of electron beam sustained discharge is presented in which a 12 keV electron beam is combined with a 2.45 GHz microwave power to excite argon gas at atmospheric pressure in a continuous mode of operation. Optical emission spectroscopy is performed over a wide wavelength range from the vacuum ultraviolet (VUV) to the near infrared (NIR). Several effects which modify the emission spectra compared to sole electron beam excitation are observed and interpreted by the changing plasma parameters such as electron density, electron temperature and gas temperature.

Dandl, Thomas; Hagn, Hermann; Neumeier, Alexander; Wieser, Jochen; Ulrich, Andreas

2014-09-01

125

Evaluation of the effects of varying moisture contents on microwave thermal emissions from agriculture fields  

Microsoft Academic Search

Three tasks related to soil moisture sensing at microwave wavelengths were undertaken: (1) analysis of data at L, X and K sub 21 band wavelengths over bare and vegetated fields from the 1975 NASA sponsored flight experiment over Phoenix, Arizona; (2) modeling of vegetation canopy at microwave wavelengths taking into consideration both absorption and volume scattering effects; and (3) investigation

H. H. K. Burke

1980-01-01

126

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

127

Emission, absorption and group delay of microwaves in the atmosphere in relation to water vapour content over the Indian subcontinent  

NASA Technical Reports Server (NTRS)

The advent of satellite communication for global coverage has apparently indicated a renewed interest in the studies of radio wave propagation through the atmosphere, in the VHF, UHF and microwave bands. The extensive measurements of atmosphere constituents, dynamics and radio meterological parameters during the Middle Atmosphere Program (MAP) have opened up further the possibilities of studying tropospheric radio wave propagation parameters, relevant to Earth/space link design. The three basic parameters of significance to radio propagation are thermal emission, absorption and group delay of the atmosphere, all of which are controlled largely by the water vapor content in the atmosphere, particular at microwave bands. As good emitters are also good absorbers, the atmospheric emission as well as the absorption attains a maximum at the frequency of 22.235 GHz, which is the peak of the water vapor line. The group delay is practically independent of frequency in the VHF, UHF and microwave bands. However, all three parameters exhibit a similar seasonal dependence originating presumably from the seasonal dependence of the water vapor content. Some of the interesting results obtained from analyses of radiosonde data over the Indian subcontinent collected by the India Meteorological Department is presented.

Sen, A. K.; Gupta, A. K. D.; Karmakar, P. K.; Barman, S. D.; Bhattacharya, A. B.; Purkait, N.; Gupta, M. K. D.; Sehra, J. S.

1985-01-01

128

Comparison of 2.8- and 21-cm microwave radiometer observations over soils with emission model calculations  

NASA Technical Reports Server (NTRS)

An airborne experiment was conducted under NASA auspices to test the feasibility of detecting soil moisture by microwave remote sensing techniques over agricultural fields near Phoenix, Arizona at midday of April 5, 1974 and at dawn of the following day. Extensive ground data were obtained from 96 bare, sixteen hectare fields. Observations made using a scanning (2.8 cm) and a nonscanning (21 cm) radiometer were compared with the predictions of a radiative transfer emission model. It is shown that (1) the emitted intensity at both wavelengths correlates best with the near surface moisture, (2) surface roughness is found to more strongly affect the degree of polarization than the emitted intensity, (3) the slope of the intensity-moisture curves decreases in going from day to dawn, and (4) increased near surface moisture at dawn is characterized by increased polarization of emissions. The results of the experiment indicate that microwave techniques can be used to observe the history of the near surface moisture. The subsurface history must be inferred from soil physics models which use microwave results as boundary conditions.

Burke, W. J.; Schmugge, T.; Paris, J. F.

1979-01-01

129

Noise Storms and the Structure of Microwave Emission of Solar Active Regions  

Microsoft Academic Search

Solar radio and microwave sources were observed with the Very Large Array (VLA) and the RATAN-600, providing high spatial resolution at 91 cm (VLA) and detailed spectral and polarization data at microwave wavelengths (1.7 to 20 cm - RATAN). The radio observations have been compared with images from the Soft X-ray Telescope (SXT) aboard theYohkoh satellite and with full-disk phoptospheric

V. M. Bogod; V. Garimov; G. B. Gelfreikh; K. R. Lang; R. F. Willson; J. N. Kile

1995-01-01

130

Noise storms and the structure of microwave emission of solar active regions  

Microsoft Academic Search

Solar radio and microwave sources were observed with the Very Large Array (VLA) and the RATAN-600, providing high spatial resolution at 91 cm (VLA) and detailed spectral and polarization data at microwave wavelengths (1.7 to 20 cm - RATAN). The radio observations have been compared with images from the Soft X-ray Telescope (SXT) aboard theYohkoh satellite and with full-disk phoptospheric

V. M. Bogod; V. Garimov; G. B. Gelfreikh; K. R. Lang; R. F. Willson; J. N. Kile

1995-01-01

131

Coupling the snow thermodynamic model SNOWPACK with the microwave emission model of layered snowpacks for subarctic and arctic snow water equivalent retrievals  

NASA Astrophysics Data System (ADS)

Satellite-passive microwave remote sensing has been extensively used to estimate snow water equivalent (SWE) in northern regions. Although passive microwave sensors operate independent of solar illumination and the lower frequencies are independent of atmospheric conditions, the coarse spatial resolution introduces uncertainties to SWE retrievals due to the surface heterogeneity within individual pixels. In this article, we investigate the coupling of a thermodynamic multilayered snow model with a passive microwave emission model. Results show that the snow model itself provides poor SWE simulations when compared to field measurements from two major field campaigns. Coupling the snow and microwave emission models with successive iterations to correct the influence of snow grain size and density significantly improves SWE simulations. This method was further validated using an additional independent data set, which also showed significant improvement using the two-step iteration method compared to standalone simulations with the snow model.

Langlois, A.; Royer, A.; Derksen, C.; Montpetit, B.; Dupont, F.; GoïTa, K.

2012-12-01

132

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

NASA Astrophysics Data System (ADS)

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 at global scale is affected by fractional forest. Whereas the effect of the vegetation can be corrected thanks a simple radiative model, in case of dense forests the wave penetration is limited and the sensitivity to variations of soil moisture is poor. However, most of the pixels are mixed, and a reliable estimate of forest emissivity is important to retrieve the soil moisture of the areas less affected by forest cover. Moreover, there are many sparse woodlands, where the sensitivity to variations of soil moisture is still acceptable. At the scale of spaceborne radiometers, it is difficult to have a detailed knowledge of the variables which affect the overall emissivity. In order to manage effectively these problems, the electromagnetic model developed at Tor Vergata University was combined with information available from forest literature. Using allometric equations and other information, the geometrical and dielectric inputs required by the model were related to global variables available at large scale, such as the Leaf Area Index. This procedure is necessarily approximate. In a first version of the model, forest variables were assumed to be constant in time, and were simply related to the maximum yearly value of Leaf Area Index. Moreover, a unique sparse distribution of trunk diameters was assumed. Finally, the temperature distribution within the crown canopy was assumed to be uniform. The model is being refined, in order to consider seasonal variations of foliage cover, subdivided into arboreous foliage and understory contributions. Different distributions of trunk diameter are being considered. Also the effects of temperature gradients within the crown canopy are being considered. The model was tested against radiometric measurements carried out by towers and aircrafts. A new test has been done using the brightness temperatures measured over some forests in Finland by the AMIRAS radiometer, which is an airborne demonstrator of the MIRAS imaging radiometer to be launched with SMOS. The outputs produced by the model are used to fit the parameters of the simple radiative transfer model which will be used in the Level 2 soil moisture retrieval algorithm. It is planned to compare model outputs with L1C data, which will be made available during the commissioning phase. To this end, a number of adequate extended forest sites are being selected: the Amazon rain forest, the Zaire Basins, the Argentinian Chaco forest, and the Finland forest. 2. PARAMETRIC STUDIES In this paper, results of parametric simulations are shown. The emissivity at vertical and horizontal polarization is simulated as a function of soil moisture content for various conditions of forest cover. Seasonal effects are considered, and the values of Leaf Area Index in winter and summer are taken as basic inputs. The difference between the two values is attributed partially to arboreous foliage and partially to understory, while the woody biomass is assumed to be constant in time. Results indicate that seasonal effects are limited, but not negligible. The simulations are repeated for different distributions of trunk diameters. If the distributions is centered over lower diameter values, the forest is optically thicker, for a given biomass. Also the variations of brightness temperature due to a temperature gradient within the crown canopy have been estimated. The outputs are used to predict the values of a simple first order RT model. 3. COMPARISONS WITH EXPERIMENTAL DATA Results of previous comparisons between model simulations and experimental data are summarized. Experimental data were collected by tower, in the Julich and Les Landes forest (Bray site) and by aircraft, ove

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

2009-04-01

133

Optical emission spectroscopy for simultaneous measurement of plasma electron density and temperature in a low-pressure microwave induced plasma  

NASA Astrophysics Data System (ADS)

The simple optical emission spectroscopy technique for diagnostics of low pressure microwave induced plasma (MIP) in hydrogen or in MIP seeded with hydrogen is described and tested. This technique uses the Boltzmann plot of relative line intensities along Balmer spectral series in conjunction with the criterion for partial local thermodynamic equilibrium for low electron density (Ne) plasma diagnostics. The proposed technique is tested in a low pressure MIP discharge for simultaneous determination of electron density Ne (1017-1018 m-3) and temperature Te.

Konjevi?, N.; Jovi?evi?, S.; Ivkovi?, M.

2009-10-01

134

Evaluation of the effects of varying moisture contents on microwave thermal emissions from agriculture fields  

NASA Technical Reports Server (NTRS)

Three tasks related to soil moisture sensing at microwave wavelengths were undertaken: (1) analysis of data at L, X and K sub 21 band wavelengths over bare and vegetated fields from the 1975 NASA sponsored flight experiment over Phoenix, Arizona; (2) modeling of vegetation canopy at microwave wavelengths taking into consideration both absorption and volume scattering effects; and (3) investigation of overall atmospheric effects at microwave wavelengths that can affect soil moisture retrieval. Data for both bare and vegetated fields are found to agree well with theoretical estimates. It is observed that the retrieval of surface and near surface soil moisture information is feasible through multi-spectral and multi-temporal analysis. It is also established that at long wavelengths, which are optimal for surface sensing, atmospheric effects are generally minimal. At shorter wavelengths, which are optimal for atmosheric retrieval, the background surface properties are also established.

Burke, H. H. K.

1980-01-01

135

Attenuation of soil microwave emissivity by corn and soybeans at 1.4 and 5 GHz  

NASA Technical Reports Server (NTRS)

Theory and experiments have shown that passive microwave radiometers can be used to measure soil moisture. However, the presence of a vegetative cover alters the measurement that might be obtained under bare conditions. Deterministically accounting for the effect of vegetation and developing algorithms for extracting soil moisture from observations of a vegetable-soil complex present significant obstacles to the practical use of this approach. The presence of a vegetation canopy reduces the sensitivity of passive microwave instruments to soil moisture variations. The reduction in sensitivity, as compared to a bare-soil relationship, increases as microwave frequency increases, implying that the longest wavelength sensors should provide the most information. Sensitivity also decreases as the amount of vegetative wet biomass increases for a given type of vegetation.

Jackson, Thomas J.; O'Neill, Peggy E.

1989-01-01

136

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

137

Publicly Available Numerical Codes for Modeling the X-ray and Microwave Emissions from Solar and Stellar Activity  

NASA Technical Reports Server (NTRS)

We have posted numerical codes on the Web for modeling the bremsstrahlung x-ray emission and the a gyrosynchrotron radio emission from solar and stellar activity. In addition to radiation codes, steady-state and time-dependent Fokker-Planck codes are provided for computing the distribution and evolution of accelerated electrons. A 1-D hydrodynamics code computes the response of the stellar atmosphere (chromospheric evaporation). A code for modeling gamma-ray line spectra is also available. On-line documentation is provided for each code. These codes have been developed for modeling results from the High Energy Solar Spectroscopic Imager (HESSI) along related microwave observations of solar flares. Comprehensive codes for modeling images and spectra of solar flares are under development. The posted codes can be obtained on NASA/Goddard's HESSI Web Site at http://hesperia.gsfc.nasa.gov/hessi/modelware.htm. This work is supported in part by the NASA Sun-Earth Connection Program.

Holman, Gordon D.; Mariska, John T.; McTiernan, James M.; Ofman, Leon; Petrosian, Vahe; Ramaty, Reuven; Fisher, Richard R. (Technical Monitor)

2001-01-01

138

Discovery of Microwave Emission from Four Nearby SolarType G Stars  

E-print Network

with age and to become undetectable with present­day instruments at spectral types earlier than K. The Sun Institut f¨ur Astronomie, ETH Zentrum 8092 Z¨urich, Switzerland Radiowaves from the Sun were detected 50 to 3000 times stronger than the quiet Sun. The microwaves most likely originate from a large number

Guedel, Manuel

139

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

140

Microwave emission from TW100 fs laser irradiation of gas jet  

Microsoft Academic Search

A new kind of high power tunable microwave radiation source is studied theoretically and experimentally. Following the previous works presented by Dorranian et al. (2003, 2004) in this paper more details about the radiation is presented. The theory of the radiation is developed to calculate the radiation spatial distribution, and more discussion on radiation behavior and characteristics is done. In

Davoud Dorranian; Mahmood Ghoranneviss; Mikhail Starodubtsev; Noboru Yugami; Yasushi Nishida

2005-01-01

141

Measuring the temperature depth profile in biological subjects through characteristic thermal microwave emissions  

Microsoft Academic Search

We present a method of deducing the depth dependence of the temperature profile in a body by measuring the brightness temperature at a number of different microwave wavelengths. We present a theoretical basis for the method and experimental verification based on a two-layer liquid model and living subjects. We develop and verify a method for determining the temperature profile of

V. S. Troitskii; E. A. Aranzhereev; A. V. Gustov; A. I. Oladyshkina; L. K. Siz'mina; R. V. Troitskii; V. N. Tseitlina

1986-01-01

142

Multielement Analysis of Food by Microwave Digestion and Inductively Coupled Plasma-Atomic Emission Spectrometry  

Microsoft Academic Search

A microwave digestion procedure for multi-elemental analysis of food was developed using one program to digest a variety of food matrices at the same time. A single program was enabled by an analytical portion mass based on the food's energy content calculated from macronutrient data (fat, protein and carbohydrate). The procedure allows a maximum mass to be analyzed for each

Scott P. Dolan; Stephen G. Capar

2002-01-01

143

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

144

Microwave radio emissions of negative cloud-to-ground lightning flashes  

NASA Astrophysics Data System (ADS)

We report preliminary results of a new observational study of microwave-frequency electromagnetic radiation that is emitted by lightning discharge processes. Radiation was observed with a ceramic patch antenna and a digital radio receiver tuned to a center frequency of 1.63 GHz and a bandwidth of 2 MHz. The recorded radiation waveforms are compared with data collected by the Oklahoma Lightning Mapping Array (OKLMA) lightning mapping system and the co-located Earth Networks Total Lightning Network (ENTLN) broadband electric field antenna. Microwave radiation was observed to occur during preliminary breakdown, negative stepped leader breakdown, negative dart leader breakdown, and return strokes. Characteristic radiation signatures were observed, including trains of individually resolvable impulses during breakdown and brief but intense trains of noise-like bursts during return strokes.

Petersen, D.; Beasley, W.

2014-01-01

145

Near-infrared digital photography to estimate snow correlation length for microwave emission modeling.  

PubMed

The study is based on experimental work conducted in alpine snow. We made microwave radiometric and near-infrared reflectance measurements of snow slabs under different experimental conditions. We used an empirical relation to link near-infrared reflectance of snow to the specific surface area (SSA), and converted the SSA into the correlation length. From the measurements of snow radiances at 21 and 35 GHz, we derived the microwave scattering coefficient by inverting two coupled radiative transfer models (the sandwich and six-flux model). The correlation lengths found are in the same range as those determined in the literature using cold laboratory work. The technique shows great potential in the determination of the snow correlation length under field conditions. PMID:19104524

Toure, Ally Mounirou; Goïta, Kalifa; Royer, Alain; Mätzler, Christian; Schneebeli, Martin

2008-12-20

146

Anomalous Light Emission from Metal Phthalocyanine Films on Au(111) Activated by Tunneling-Current-Induced Surface Plasmon  

Microsoft Academic Search

We performed a scanning-tunneling-microscopy-induced light emission (STM-LE) study on Cu- and Zn-phthalocyanine films formed on a Au(111) surface. Optical emission with transition between the highest occupied and lowest unoccupied molecular orbitals (HOMO--LUMO) was observed at bias voltages lower than the energy corresponding to the molecular HOMO--LUMO gap. The voltage and current dependences of STM-LE intensities show an inconsistency for both

Arifumi Okada; Ken Kanazawa; Kiwamu Hayashi; Naohiro Okawa; Takehiro Kurita; Osamu Takeuchi; Hidemi Shigekawa

2010-01-01

147

Theory of microwave and X-ray emission. [application to behavior of nonthermal electrons created at impulsive phase of solar flares  

NASA Technical Reports Server (NTRS)

The behaviour of the nonthermal electrons created at the impulsive phase of flares has been deduced from the microwave impulsive bursts and hard X-ray burst by many researchers. There is almost no doubt of the emission mechanisms that radio emissions are due to gyrosynchrotron emission and hard X-rays are collisional bremsstrahlung. However, there remain three controversial problems. One is whether the emission sources of the microwave impulsive burst and hard X-ray burst are common or not. Another is whether the injection of the nonthermal electrons into the source is impulsive or continuous. The other is the relation among the nonthermal electrons, soft X-rays, EUV flash, H-alpha kernels, and white light flares. These three problems are not independent of each other.

Takakura, T.

1973-01-01

148

Influence of (FeO + TiO2) abundance on the thermal emission from the lunar regolith using Chang'E-2 microwave radiometer data  

NASA Astrophysics Data System (ADS)

Abstract?The microwave radiometer data obtained from Chang’E-2 mission (CELMS data) has provided new opportunity to study the influence of the (FeO+TiO2) abundance on the microwave thermal emission of the lunar regolith. In this paper, the radiative transfer simulation is employed to study the change of the brightness temperature with (FeO+TiO2) abundance at different frequencies and surface temperature. The (FeO+TiO2) abundance are derived from Clementine UV-VIS data and the samples from Apollo, Luna and Surveyor projects. The simulation results along the Equator indicate that the (FeO+TiO2) abundance has strong impact on the microwave thermal emission of the lunar regolith. However, the data along the Longitude 0° shows that the (FeO+TiO2) abundance is not the dominant influential factor of the microwave thermal emission of the lunar regolith. Specifically, the abnormal brightness temperature at 160°W (Unnamed crater), 138°W (Crater Vavilov), 125°W (Crater Hertzsprung), 116°E (Crater Abul Wáfa), 119°E (Crater Heron), 130°E (Crater Catena Gregory) and 140°E (Crater Catena Mendeleev) shows that the (FeO+TiO2) abundance is not the only influential factor for the observed brightness temperature. In addition, the correlations between the four-channel brightness temperature and the (FeO+TiO2) abundance in Apollo landing site and along the Equator both indicate that the (FeO+TiO2) abundance is slightly decreasing with depth. The research is essential for the inversion of the lunar regolith parameters with the microwave radiometer data from Chang’E satellites. Keywords: lunar regolith, microwave thermal emission, CELMS data, (FeO+TiO2) abundance

Meng, Zhiguo; Ping, Jinsong; Xu, Yi; Cai, Zhanchuan; Zheng, Yongchun

149

Behaviour of a desolvation system based on microwave radiation heating for use in inductively coupled plasma atomic emission spectrometry  

NASA Astrophysics Data System (ADS)

The present paper describes the preliminary results obtained with a desolvation system for inductively coupled plasma atomic emission spectrometry that incorporates a heating unit based on microwave (MW) radiation. This system has been called Microwave Desolvation System (MWDS). The results have proved that MW radiation can be considered as a good choice for aerosol heating in a sample introduction system. MW radiation seems to be a more uniform way of aerosol desolvation than conductive/convective heating (i.e. lower radial temperature gradients), the degree of vaporization of the droplets is less dependent on the liquid flow rate ( Ql), and also the background noise associated with the vaporization of droplets is reduced. As regards the results obtained with MWDS, in comparison with a conventional desolvation system (CDS), they are very dependent on Ql. When heating is applied, the amount of analyte that leaves the heating step increases by 30-60% with the MWDS, irrespective of Ql, whereas for the CDS this increase is very high (up to 300%) at low Ql values (0.4 ml min -1), but almost negligible at high Ql values (2.4 ml min -1). In agreement with this, the analytical figures of merit are favourable to the CDS at low flow rates, and to the MWDS at high liquid flows. Under all the conditions studied, the amount of solvent that leaves the condensation unit are lower for MWDS than for CDS.

Gras, Luis; Mora, Juan; Todolí, JoséL.; Hernandis, Vicente; Canals, Antonio

1997-07-01

150

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

151

Long-term X-ray Changes in the Emission from the Anomalous X-ray Pulsar 4U 0142+61  

NASA Astrophysics Data System (ADS)

We present results obtained from X-ray observations of the anomalous X-ray pulsar (AXP) 4U 0142+61 taken between 2000 and 2008 using XMM-Newton, Chandra, and Swift. These observations coincide with periods of long-term changes and burst epochs previously reported using the Rossi X-ray Timing Explorer (RXTE). In observations taken before 2006, we find that the pulse profile became more sinusoidal and the pulsed fraction increased with time. These results confirm those derived using RXTE and expand the observed evolution to energies below 2 keV. The total flux in the 0.5-10 keV band determined with XMM-Newton is observed to be nearly constant in observations taken before 2006, while an increase of ~10% is seen afterwards and coincides with the burst activity detected from the source in 2006-2007. After these bursts, the evolution toward more sinusoidal pulse profiles ceased while the flux and pulsed fraction returned to pre-bursts levels. No evidence for large-scale, long-term changes in the emission as a result of the bursts is seen. We also report on observations taken with the Gemini telescope after two bursts which show source magnitudes consistent with previous measurements. Our results demonstrate the wide range of X-ray variability characteristics seen in AXPs and we discuss them in light of current emission models for these sources.

Gonzalez, M. E.; Dib, R.; Kaspi, V. M.; Woods, P. M.; Tam, C. R.; Gavriil, F. P.

2010-06-01

152

Low Temperature Studies of Anomalous Surface Shielding and Related Phenomena.  

National Technical Information Service (NTIS)

Experiments were conducted to determine the force of gravity on positions and electrons. An anomalous, low temperature shielding effect was discovered in copper and studied. It is believed that sharp increases in the microwave surface conductivity of copp...

W. M. Fairbank

1986-01-01

153

Microwave emission from snow and glacier ice. [brightness temperature for snow fields  

NASA Technical Reports Server (NTRS)

The microwave brightness temperature for snow fields was studied assuming that the snow cover consists of closely packed scattering spheres which do not interact coherently. The Mie scattering theory was used to compute the volume scattering albedo. It is shown that in the wavelength range from 0.8 to 2.8 cm, most of the micro-radiation emanates from a layer 10 meters or less in thickness. It is concluded that it is possible to determine snow accumulation rates as well as near-surface temperature.

Chang, T. C.; Gloersen, P.; Schmugge, T.; Wilheit, T. T.; Zwally, H. J.

1975-01-01

154

Optical emission spectroscopy of microwave-plasmas at atmospheric pressure applied to the growth of organosilicon and organotitanium nanopowders  

NASA Astrophysics Data System (ADS)

An atmospheric-pressure plasma sustained by an electromagnetic surface wave (SW) in the microwave regime combined with a bubbler/flash evaporator for the injection of liquid precursors was used to produce organosilicon and organotitanium nanopowders. Following the addition of hexamethyldisiloxane (HMDSO) vapors in the nominally pure argon plasma, optical emission spectra revealed the apparition of strong C2 molecular bands along with Si and Balmer H emission lines. Such features were not observed in our atmospheric-pressure Ar/HMDSO discharges controlled by dielectric barriers, indicating that microwave plasmas are characterized by much higher fragmentation levels of the precursors due to much higher electron densities. Emission spectra from the Ar/HMDSO SW plasma further showed a high-intensity continuum, the intensity of which decreased with time as powders started to form on the discharge tube walls. In presence of titanium isopropoxide (TTIP) vapors in the nominally pure Ar plasma, the emission was dominated by Ar and Ti lines, with no trace of carbon and no continuum. Fourier-Transform Infrared (FTIR) Spectroscopy of the powders formed in Ar/HMDSO plasmas showed very strong Si-(CH3)x and O-Si-(CH3)x bands, which is consistent with the formation of silicon oxycarbide. Transmission Electron Microscopy (TEM) further showed tube and sheet-like nanofeatures as well as larger structures consisting of agglomerated primary clusters. On the other hand, introduction of O2 in Ar/HMDSO plasmas produced only round-like nanoparticles with strong Si-O-Si bands and no trace of carbon, consistent with the formation of SiOx. The average size of the silica nanoparticles was 50 nm. FTIR spectra of powders formed in Ar/TTIP plasmas showed strong Ti-O signals, even without the addition of O2 in the gas phase. Corresponding TEM analysis showed nano- and agglomerated features comparable to those obtained in Ar/HMDSO although the average size of the titanate nanoparticles was smaller (10 nm). This set of data indicates that SW plasmas represent a promising parametric tool not only to achieve nanopowders with tailored properties for applications, but also for fundamental studies of nanodusty plasmas at atmospheric-pressure.

Kilicaslan, A.; Levasseur, O.; Roy-Garofano, V.; Profili, J.; Moisan, M.; Côté, C.; Sarkissian, A.; Stafford, L.

2014-03-01

155

Research relative to angular distribution of snow reflectance/snow cover characterization and microwave emission  

NASA Technical Reports Server (NTRS)

Remote sensing has been applied in recent years to monitoring snow cover properties for applications in hydrologic and energy balance modeling. In addition, snow cover has been recently shown to exert a considerable local influence on weather variables. Of particular importance is the potential of sensors to provide data on the physical properties of snow with high spatial and temporal resolution. Visible and near-infrared measurements of upwelling radiance can be used to infer near-surface properties through the calculation of albedo. Microwave signals usually come from deeper within the snow pack and thus provide depth-integrated information, which can be measured through clouds and does not relay on solar illumination.Fundamental studies examining the influence of snow properties on signals from various parts of the electromagnetic spectrum continue in part because of the promise of new remote sensors with higher spectral and spatial accuracy. Information in the visible and near-infrared parts of the spectrum comprise nearly all available data with high spatial resolution. Current passive microwave sensors have poor spatial resolution and the data are problematic where the scenes consist of mixed landscape features, but they offer timely observations that are independent of cloud cover and solar illumination.

Dozier, Jeff; Davis, Robert E.

1987-01-01

156

Rock fraction effects on the interpretation of microwave emission from soils  

NASA Technical Reports Server (NTRS)

The effect of the rock fraction of soil on emissivity is presently investigated through a combination of laboratory dielectric measurements and field observation of emissivity from soils with and without rocks. The rock fraction reduced the range of emissivity; beyond this, it appears to be important only in determining the moisture in the soil component. Data gathered at 6 cm indicate that the presence of rocks renders this and shorter wavelengths useless as soil-moisture sensors. Modeling of the 21-cm case suggest that rock-fraction effects on soil dielectric properties can be compensated for by the greater surface roughness.

Jackson, Thomas J.; Kostov, Kosta G.; Saatchi, Sasan S.

1992-01-01

157

Preparation, Infrared Emissivity, and Dielectric and Microwave Absorption Properties of Fe-Doped ZnO Powder  

NASA Astrophysics Data System (ADS)

Fe-doped ZnO powders have been synthesized by the coprecipitation method using zinc nitrate [Zn(NO3)2·6H2O] as starting material, urea [CO(NH2)2] as precipitator, and ferric nitrate [Fe(NO3)3·9H2O] as doping source. The microstructure of the prepared powders has been characterized by x-ray diffraction and scanning electron microscopy. Results show that, when the molar ratio of Fe to (Zn + Fe) was less than 0.09, the prepared powder was ZnO(Fe) solid solution, and the ZnFe2O4 impurity phase appeared when the Fe doping content was further increased. The electric permittivity in the frequency range of 8.2 GHz to 12.4 GHz and the average infrared emissivity in the wavelength range of 8 ?m to 14 ?m have been determined for the prepared powders. The average infrared emissivity decreased with increasing Fe doping content. The real ( ?') and imaginary part ( ??) of the permittivity of the prepared powders showed opposite trends. When the molar ratio of Fe to (Zn + Fe) was 0.03, the prepared Fe-doped ZnO powder demonstrated the best microwave absorption in the frequency range of 8.2 GHz to 12.4 GHz.

Su, Xiaolei; Jia, Yan; Liu, Xiaoqin; Wang, Junbo; Xu, Jie; He, Xinhai; Fu, Chong; Liu, Songtao

2014-11-01

158

Preparation, Infrared Emissivity, and Dielectric and Microwave Absorption Properties of Fe-Doped ZnO Powder  

NASA Astrophysics Data System (ADS)

Fe-doped ZnO powders have been synthesized by the coprecipitation method using zinc nitrate [Zn(NO3)2·6H2O] as starting material, urea [CO(NH2)2] as precipitator, and ferric nitrate [Fe(NO3)3·9H2O] as doping source. The microstructure of the prepared powders has been characterized by x-ray diffraction and scanning electron microscopy. Results show that, when the molar ratio of Fe to (Zn + Fe) was less than 0.09, the prepared powder was ZnO(Fe) solid solution, and the ZnFe2O4 impurity phase appeared when the Fe doping content was further increased. The electric permittivity in the frequency range of 8.2 GHz to 12.4 GHz and the average infrared emissivity in the wavelength range of 8 ?m to 14 ?m have been determined for the prepared powders. The average infrared emissivity decreased with increasing Fe doping content. The real (?') and imaginary part (??) of the permittivity of the prepared powders showed opposite trends. When the molar ratio of Fe to (Zn + Fe) was 0.03, the prepared Fe-doped ZnO powder demonstrated the best microwave absorption in the frequency range of 8.2 GHz to 12.4 GHz.

Su, Xiaolei; Jia, Yan; Liu, Xiaoqin; Wang, Junbo; Xu, Jie; He, Xinhai; Fu, Chong; Liu, Songtao

2014-07-01

159

Microwave Radio Emission from the Red Dwarf Star Yz-Canis  

NASA Astrophysics Data System (ADS)

We present observations at 5 GHz of flaring and quiescent emission from the red dwarf star YZ CMi, obtained with the Jodrell Bank broad-band interferometer. Weak (1 to 2 mJy) quiescent emission varying over time-scales of hours was detected, in addition to a strong outburst on 1988 October 6 which reached 42 mJy and lasted several minutes. Low-level flaring at ˜15 mJy and of short duration (<20 s) also occurs continuously at a rate of 5 to 6 events per hour.

Spencer, R. E.; Davis, R. J.; Zafiropoulos, B.; Nelson, R. F.

1993-11-01

160

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

Microsoft Academic Search

Intercepted precipitation was found to increase the 1.4 GHz brightness temperature of maize. This effect is opposite that of dew, another form of free water in a vegetation canopy. If the effects of intercepted precipitation and dew are to be modeled correctly, emission models must be used in conjunction with a land surface process model in order to separate the

Brian Hornbuckle; Tony England; Martha Anderson

2006-01-01

161

Quasi-periodic components of solar microwave emission preceded CME's onset  

NASA Astrophysics Data System (ADS)

The results of observations at the radio-astronomical station NIRFI "Zimenki" are examined. Pre-eruption manifestations can be detected over different time scales: from several days, which is typical to the evolution of active region in whole, to several hours and tens of minutes, which leads to the formation of conditions for CME initiation and propagation. Primarily this process is developed as wave motion. For example, a study of the evolution of radio emission in January 2005 discovered the growth of amplitude of long-period pulsations with a period of more than 20 minutes in centimetre solar radio emission three days before coronal mass ejections. During the time intervals of 25 to 15 minutes prior to CMEs registration the oscillations of substantially smaller period (t 6-22 s) occurred, which were apparently connected to waves in coronal loops. The obtained result is close to the results of other authors, based on the observations of solar radio emission with the high spatial resolution. Thus, it is shown that the use of patrol multi wave observational data with the high sensitivity and a sufficient time resolution is possible for the analysis of the quasi-periodic components of radio emission and their dynamics.

Sheyner, Olga; Fridman, Vladimir

162

Emissivity measurements in thin metallized membrane reflectors used for microwave radiometer sensors  

NASA Astrophysics Data System (ADS)

This paper is concerned with electromagnetic losses in metallized films used for inflatable reflectors. An inflatable membrane is made of tough elastic material such as Kapton, and it is not electromagnetically reflective by design. A film of conducting metal is added to the membrane to enhance its reflective properties. Since the impetus for use of inflatables for spacecraft is the light weight and compact packaging, it is important that the metal film be as thin as possible. However, if the material is not conductive or thick enough, the radiation due to the emissivity of the reflector could be a significant part of the radiation gathered by the radiometer. The emissivity would be of little consequence to a radar or solar collector; but for a radiometer whose signal is composed of thermal radiation, this contribution could be severe. Bulk properties of the metal film cannot be used to predict its loss. For this reason, a program of analysis and measurement was undertaken to determine the emissivities of a number of candidate metallized film reflectors. This paper describes the three types of measurements which were performed on the metallized thin films: (1) a network analyzer system with an L-band waveguide; (2) an S-band radiometer; and (3) a network analyzer system with a C-band antenna free-space transmission system.

Schroeder, Lyle C.; Cravey, Robin L.; Scherner, Michael J.; Hearn, Chase P.; Blume, Hans-Juergen C.

1995-06-01

163

Calculations of the spectral nature of the microwave emission from soils. [Arizona and Georgia  

NASA Technical Reports Server (NTRS)

The brightness temperatures for a set of soil profiles observed at USDA facilities in Arizona and Georgia were calculated at the wavelengths of 2.8, 6, 11, 21, and 49 cm using a coherent radiative transfer model. The soil moisture sampling depth is found to be a function of wavelength and is in the range 0.06 to 0.1 of a wavelength. The thermal sampling depth also depends on wavelength and is approximately equal to one wavelength at dry soil condition and 0.1 - 0.5 wavelengths at wet soil conditions. Calculated values of emissivity show strong diurnal variations when the soils are wet, while there is little diurnal change when the soil is dry. The soil moistures within the four depth intervals of 0-2, 0-5, 0-9, and 0-15 cm were parameterized as function of the calculated emissivity and brightness temperature. Best-fit parameters and correlation coefficients are presented for five wavelengths. Interrelationships among the effective temperature, surface temperature, and emissivity are displayed.

Mo, T.; Schmugge, T. J.; Choudhury, B. J. (principal investigators)

1980-01-01

164

Continuous-flow determination of aqueous sulfur by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry with gas-phase sample introduction  

Microsoft Academic Search

A simple continuous-flow generation of volatile hydrogen sulfide and sulfur dioxide by acidification of aqueous sulfide and sulfite ions, respectively, is described for the determination of low concentrations of sulfur by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry (MIP-AES) in the normal ultraviolet (UV) and vacuum ultraviolet (VUV) regions of the spectrum. For measuring spectral lines in the VUV region,

Taketoshi Nakahara; Toshio Mori; Satoru Morimoto; Hiroshi Ishikawa

1995-01-01

165

[Determination of Pd, Pt and Au by microwave plasma torch atomic emission spectrometry using an on-line clean-up].  

PubMed

In this paper, in the presence of Li+, Na+, K+, Ca2+ and Mg2+, determinations of Pd, Pt and Au by microwave plasma torch atomic emission spectrometry (MPT-AES) using an on-line clean-up were studied. It was shown from the experiments that these interfering matrix elements might be removed with the strong acidic cation exchange resin. The method was applied to the analysis of some practical samples and the results obtained were satisfactory. PMID:12953579

Zhang, L; Zhao, L; Zhang, H; Liu, Q; Jin, Q

2001-02-01

166

Enhancement of secondary electron emission by annealing and microwave hydrogen plasma treatment of ion-beam-damaged diamond films  

NASA Astrophysics Data System (ADS)

In this work we investigate the influence of annealing and microwave (MW) hydrogen plasma exposure of ion-beam-irradiated diamond film surfaces. In particular, we are interested in the recovery of secondary electron emission (SEE) and negative electron affinity (NEA) by removal of the damaged layer. To this aim, we correlate the SEE of variously treated Xe+ ion-damaged diamond films with their bonding structure in the near-surface region, as identified by near-edge x-ray absorption fine structure (NEXAFS) spectroscopy and x-ray photoelectron spectroscopy. The 30 keV Xe+ ion bombardment of hydrogenated polycrystalline diamond films to a dose of 2×1015 cm-2 results in the transformation of the near-surface region of a diamond film to sp2-bonded amorphous carbon, increased oxygen adsorption, shift of the electron affinity from negative to positive, and strong degradation of its electron emission properties, although it does not induce a pronounced depletion of hydrogen. Exposure of the ion-bombarded films to MW hydrogen plasma treatment for 30 min produces NEA diamond surfaces, but only partially regenerates SEE properties, retains some imperfection in the near-surface atomic layers, as determined by NEXAFS, and the concentration of oxygen remains relatively high. Subsequent annealing to 610 °C produces oxygen-free diamond films and somewhat increases their SEE. Annealing to 1000 °C results in desorption of the surface hydrogen, formation of positive electron affinity surfaces, and drastically degrades their electron emission properties. Prolonged (up to three hours) MW hydrogen plasma treatment of as-implanted diamond films gradually improves their crystal quality and results in a further increase of SEE intensity. The SEE intensity after three hours MW hydrogen plasma exposure of the ion-beam-irradiated films was found to be ˜50% above the value obtained for the as-deposited diamond films. This treatment does not, however, substantially reduce the concentration of oxygen in the previously damaged diamond, indicating its bulk diffusion during or after ion bombardment. Our results show that removal of damage from a highly disordered diamond surface and recovery of its electron emission properties are possible by MW hydrogen plasma. However, it is a slow process. This is most likely due to the very low etching rate of the low-level damage at the end of the ion beam range.

Laikhtman, A.; Hoffman, A.

2002-02-01

167

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

168

Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds  

NASA Astrophysics Data System (ADS)

We present a full-sky 100 ?m map that is a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed. Before using the ISSA maps, we remove the remaining artifacts from the IRAS scan pattern. Using the DIRBE 100 and 240 ?m data, we have constructed a map of the dust temperature so that the 100 ?m map may be converted to a map proportional to dust column density. The dust temperature varies from 17 to 21 K, which is modest but does modify the estimate of the dust column by a factor of 5. The result of these manipulations is a map with DIRBE quality calibration and IRAS resolution. A wealth of filamentary detail is apparent on many different scales at all Galactic latitudes. In high-latitude regions, the dust map correlates well with maps of H I emission, but deviations are coherent in the sky and are especially conspicuous in regions of saturation of H I emission toward denser clouds and of formation of H2 in molecular clouds. In contrast, high-velocity H I clouds are deficient in dust emission, as expected. To generate the full-sky dust maps, we must first remove zodiacal light contamination, as well as a possible cosmic infrared background (CIB). This is done via a regression analysis of the 100 ?m DIRBE map against the Leiden-Dwingeloo map of H I emission, with corrections for the zodiacal light via a suitable expansion of the DIRBE 25 ?m flux. This procedure removes virtually all traces of the zodiacal foreground. For the 100 ?m map no significant CIB is detected. At longer wavelengths, where the zodiacal contamination is weaker, we detect the CIB at surprisingly high flux levels of 32 +/- 13 nW m-2 sr-1 at 140 ?m and of 17 +/- 4 nW m-2 sr-1 at 240 ?m (95% confidence). This integrated flux ~2 times that extrapolated from optical galaxies in the Hubble Deep Field. The primary use of these maps is likely to be as a new estimator of Galactic extinction. To calibrate our maps, we assume a standard reddening law and use the colors of elliptical galaxies to measure the reddening per unit flux density of 100 ?m emission. We find consistent calibration using the B-R color distribution of a sample of the 106 brightest cluster ellipticals, as well as a sample of 384 ellipticals with B-V and Mg line strength measurements. For the latter sample, we use the correlation of intrinsic B-V versus Mg2 index to tighten the power of the test greatly. We demonstrate that the new maps are twice as accurate as the older Burstein-Heiles reddening estimates in regions of low and moderate reddening. The maps are expected to be significantly more accurate in regions of high reddening. These dust maps will also be useful for estimating millimeter emission that contaminates cosmic microwave background radiation experiments and for estimating soft X-ray absorption. We describe how to access our maps readily for general use.

Schlegel, David J.; Finkbeiner, Douglas P.; Davis, Marc

1998-06-01

169

Study of power enhancement and frequency shifting of microwave emission in a plasma filled non-uniform BWO  

Microsoft Academic Search

Summary form only given. Recent experiments reported an improved efficiency in high power microwave generation by applying a non-uniform slow wave structure (SWS) or using a plasma filling in a backward wave oscillator (BWO). A combined scheme of plasma filling in a non-uniform SWS is investigated to further increase microwave output power. An annular cathode of radius 1 cm produces

D. Young; O. Ishihara; C. Grabowski; E. Schamiloglu; J. Gahl

1998-01-01

170

Application of Microwave Plasma Atomic Emission Spectrometry (MP-AES) for environmental monitoring of industrially contaminated sites in Hyderabad City.  

PubMed

Recently introduced microwave plasma-atomic emission spectroscopy (MP-AES) represents yet another and very important addition to the existing array of modern instrumental analytical techniques. In this study, an attempt is made to summarize the performance characteristics of MP-AES and its potential as an analytical tool for environmental studies with some practical examples from Patancheru and Uppal industrial sectors of Hyderabad city. A range of soil, sediment, water reference materials, particulate matter, and real-life samples were chosen to evaluate the performance of this new analytical technique. Analytical wavelengths were selected considering the interference effects of other concomitant elements present in different sample solutions. The detection limits for several elements were found to be in the range from 0.05 to 5 ng/g. The trace metals analyzed in both the sectors followed the topography with more pollution in the low-lying sites. The metal contents were found to be more in ground waters than surface waters. Since a decade, the pollutants are transfered from Patancheru industrial area to Musi River. After polluting Nakkavagu and turning huge tracts of agricultural lands barren besides making people residing along the rivulet impotent and sick, industrialists of Patancheru are shifting the effluents to downstream of Musi River through an 18-km pipeline from Patancheru. Since the effluent undergoes primary treatment at Common Effluent Treatment Plant (CETP) at Patanchru and travels through pipeline and mixes with sewage, the organic effluents will be diluted. But the inorganic pollutants such as heavy and toxic metals tend to accumulate in the environmental segments near and downstreams of Musi River. The data generated by MP-AES of toxic metals like Zn, Cu, and Cr in the ground and surface waters can only be attributed to pollution from Patancheru since no other sources are available to Musi River. PMID:25086712

Kamala C T; Balaram V; Dharmendra V; Satyanarayanan M; Subramanyam K S V; Krishnaiah A

2014-11-01

171

Observability of Antarctic Surface Temperature Variations on Decadal Time Scales, With High Spatial Resolution, Using Satellite Observations of Thermal Microwave Emission and Sparse Ground Measurements  

NASA Astrophysics Data System (ADS)

Knowledge of Antarctic surface temperature variations in space and time is presently based on instrumental records and interpretation of ice cores, both of which are, by practical necessity, sparse point measurements. The sufficiency of spatial sampling by such measurements remains uncertain. Spatially extensive satellite observations of 0.8 cm-wavelength (37 GHz) thermal emission can be interpreted in terms of snow surface temperature to address this problem, but such interpretation is presently limited in two important respects: (1) interpretation is restricted to regions of space and time near instrumental or other independent temperature data that are needed to infer an effective microwave emissivity; and (2) the record of suitable observations extends back only 22 years, a duration which is short compared to the timescale of many prospective temperature variations of interest. The first limitation can be addressed by estimating long-term (centennial-scale) mean surface temperature independently from satellite observations of 4.5 cm-wavelength (6.7 GHz) emission. I present the essential physical and observational validation for this estimation, and show how, together with the shorter wavelength observations, the estimation can be used to characterize microwave emissivity at 0.8 cm-wavelength (for a simplified, though usefully approximate model in which firn properties are independent of depth within the range from which the shorter-wavelength emission originates). The second limitation can be addressed using emission observations at wavelengths longer than 0.8 cm - in particular, emission at 1.8 cm - and longer-wavelengths (i.e., frequencies of 19 GHz and lower) carries information on temperature variations on decadal scales. I present a simple calculation that shows how this occurs, and note approximate agreement of the calculation with recent results by Shuman and by Fahnestock and co-workers. The underlying physics thus supports, in principle, the use of existing and prospective satellite microwave emission observations to characterize ice sheet temperature variations during a significant part of the 20th century - the key question is whether available accuracies compare well with the expected magnitudes of such temperature variations. I address this question using basic but modern geostatistical methods to estimate the accuracy of "calibration" of the satellite temperature estimates using sparse ground observations. From this follows directly an assessment of the observability of Antarctic surface temperature variations on decadal time scales, both with present data and with data likely to become available in the next decade.

Winebrenner, D. P.

2001-12-01

172

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

E-print Network

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 ...

Flores, Alejandro N.

173

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

SciTech Connect

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. [Centre de physique théorique, CNRS-Ecole Polytechnique, 91128 Palaiseau Cedex (France)] [Centre de physique théorique, CNRS-Ecole Polytechnique, 91128 Palaiseau Cedex (France)

2013-08-15

174

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.

175

The emission and scattering of L-band microwave radiation from rough ocean surfaces and wind speed measurements from the Aquarius sensor  

NASA Astrophysics Data System (ADS)

order to achieve the required accuracy in sea surface salinity (SSS) measurements from L-band radiometers such as the Aquarius/SAC-D or SMOS (Soil Moisture and Ocean Salinity) mission, it is crucial to accurately correct the radiation that is emitted from the ocean surface for roughness effects. We derive a geophysical model function (GMF) for the emission and backscatter of L-band microwave radiation from rough ocean surfaces. The analysis is based on radiometer brightness temperature and scatterometer backscatter observations both taken on board Aquarius. The data are temporally and spatially collocated with wind speeds from WindSat and F17 SSMIS (Special Sensor Microwave Imager Sounder) and wind directions from NCEP (National Center for Environmental Prediction) GDAS (Global Data Assimilation System). This GMF is the basis for retrieval of ocean surface wind speed combining L-band H-pol radiometer and HH-pol scatterometer observations. The accuracy of theses combined passive/active L-band wind speeds matches those of many other satellite microwave sensors. The L-band GMF together with the combined passive/active L-band wind speeds is utilized in the Aquarius SSS retrieval algorithm for the surface roughness correction. We demonstrate that using these L-band wind speeds instead of NCEP wind speeds leads to a significant improvement in the SSS accuracy. Further improvements in the roughness correction algorithm can be obtained by adding VV-pol scatterometer measurements and wave height (WH) data into the GMF.

Meissner, Thomas; Wentz, Frank J.; Ricciardulli, Lucrezia

2014-09-01

176

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

177

Long wavelength (>1.55 {mu}m) room temperature emission and anomalous structural properties of InAs/GaAs quantum dots obtained by conversion of In nanocrystals  

SciTech Connect

We demonstrate that molecular beam epitaxy-grown InAs quantum dots (QDs) on (100) GaAs obtained by conversion of In nanocrystals enable long wavelength emission in the InAs/GaAs material system. At room temperature they exhibit a broad photoluminescence band that extends well beyond 1.55 {mu}m. We correlate this finding with cross-sectional scanning tunneling microscopy measurements. They reveal that the QDs are composed of pure InAs which is in agreement with their long-wavelength emission. Additionally, the measurements reveal that the QDs have an anomalously undulated top surface which is very different to that observed for Stranski-Krastanow grown QDs.

Urbanczyk, A.; Keizer, J. G.; Koenraad, P. M. [COBRA Research Institute on Communication Technology, Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)] [COBRA Research Institute on Communication Technology, Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Noetzel, R. [Institute for Systems Based on Optoelectronics and Microtechnology (ISOM), ETSI Telecommunication, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)] [Institute for Systems Based on Optoelectronics and Microtechnology (ISOM), ETSI Telecommunication, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)

2013-02-18

178

Vacuum Ultraviolet Emission Spectrum Measurement of a Microwave-discharge Hydrogen-flow Lamp in Several Configurations: Application to Photodesorption of CO Ice  

NASA Astrophysics Data System (ADS)

We report measurements of the vacuum ultraviolet (VUV) emission spectra of a microwave-discharge hydrogen-flow lamp (MDHL), a common tool in astrochemistry laboratories working on ice VUV photoprocessing. The MDHL provides hydrogen Ly-? (121.6 nm) and H2 molecular emission in the 110-180 nm range. We show that the spectral characteristics of the VUV light emitted in this range, in particular the relative proportion of Ly-? to molecular emission bands, strongly depend on the pressure of H2 inside the lamp, the lamp geometry (F type versus T type), the gas used (pure H2 versus H2 seeded in He), and the optical properties of the window used (MgF2 versus CaF2). These different configurations are used to study the VUV irradiation of CO ice at 14 K. In contrast to the majority of studies dedicated to the VUV irradiation of astrophysical ice analogs, which have not taken into consideration the emission spectrum of the MDHL, our results show that the processes induced by photons in CO ice from a broad energy range are different and more complex than the sum of individual processes induced by monochromatic sources spanning the same energy range, as a result of the existence of multistate electronic transitions and discrepancy in absorption cross sections between parent molecules and products in the Ly-? and H2 molecular emission ranges.

Chen, Y.-J.; Chuang, K.-J.; Muñoz Caro, G. M.; Nuevo, M.; Chu, C.-C.; Yih, T.-S.; Ip, W.-H.; Wu, C.-Y. R.

2014-01-01

179

Simulation of the Microwave Emission of Multi-layered Snowpacks Using the Dense Media Radiative Transfer Theory: the DMRT-ML Model  

NASA Technical Reports Server (NTRS)

DMRT-ML is a physically based numerical model designed to compute the thermal microwave emission of a given snowpack. Its main application is the simulation of brightness temperatures at frequencies in the range 1-200 GHz similar to those acquired routinely by spacebased microwave radiometers. The model is based on the Dense Media Radiative Transfer (DMRT) theory for the computation of the snow scattering and extinction coefficients and on the Discrete Ordinate Method (DISORT) to numerically solve the radiative transfer equation. The snowpack is modeled as a stack of multiple horizontal snow layers and an optional underlying interface representing the soil or the bottom ice. The model handles both dry and wet snow conditions. Such a general design allows the model to account for a wide range of snow conditions. Hitherto, the model has been used to simulate the thermal emission of the deep firn on ice sheets, shallow snowpacks overlying soil in Arctic and Alpine regions, and overlying ice on the large icesheet margins and glaciers. DMRT-ML has thus been validated in three very different conditions: Antarctica, Barnes Ice Cap (Canada) and Canadian tundra. It has been recently used in conjunction with inverse methods to retrieve snow grain size from remote sensing data. The model is written in Fortran90 and available to the snow remote sensing community as an open-source software. A convenient user interface is provided in Python.

Picard, G.; Brucker, Ludovic; Roy, A.; Dupont, F.; Fily, M.; Royer, A.; Harlow, C.

2013-01-01

180

Simulation of the microwave emission of multi-layered snowpacks using the Dense Media Radiative transfer theory: the DMRT-ML model  

NASA Astrophysics Data System (ADS)

DMRT-ML is a physically based numerical model designed to compute the thermal microwave emission of a given snowpack. Its main application is the simulation of brightness temperatures at frequencies in the range 1-200 GHz similar to those acquired routinely by space-based microwave radiometers. The model is based on the Dense Media Radiative Transfer (DMRT) theory for the computation of the snow scattering and extinction coefficients and on the Discrete Ordinate Method (DISORT) to numerically solve the radiative transfer equation. The snowpack is modeled as a stack of multiple horizontal snow layers and an optional underlying interface representing the soil or the bottom ice. The model handles both dry and wet snow conditions. Such a general design allows the model to account for a wide range of snow conditions. Hitherto, the model has been used to simulate the thermal emission of the deep firn on ice sheets, shallow snowpacks overlying soil in Arctic and Alpine regions, and overlying ice on the large ice-sheet margins and glaciers. DMRT-ML has thus been validated in three very different conditions: Antarctica, Barnes Ice Cap (Canada) and Canadian tundra. It has been recently used in conjunction with inverse methods to retrieve snow grain size from remote sensing data. The model is written in Fortran90 and available to the snow remote sensing community as an open-source software. A convenient user interface is provided in Python.

Picard, G.; Brucker, L.; Roy, A.; Dupont, F.; Fily, M.; Royer, A.; Harlow, C.

2013-07-01

181

Simulation of the microwave emission of multi-layered snowpacks using the dense media radiative transfer theory: the DMRT-ML model  

NASA Astrophysics Data System (ADS)

DMRT-ML is a physically-based numerical model designed to compute the thermal microwave emission of a given snowpack. Its main application is the simulation of brightness temperatures at frequencies in the range 1-200 GHz similar to those acquired routinely by space-based microwave radiometers. The model is based on the Dense Media Radiative Transfer (DMRT) theory for the computation of the snow scattering and extinction coefficients and on the Discrete Ordinate Method (DISORT) to numerically solve the radiative transfer equation. The snowpack is modeled as a stack of multiple horizontal snow layers and an optional underlying interface representing the soil or the bottom ice. The model handles both dry and wet snow conditions. Such a general design allows the user to account for a wide range of snow conditions. Hitherto, the model has been used to simulate the thermal emission of the deep firn on ice sheets, shallow snowpacks overlying soil in Arctic and Alpine regions, and overlying ice on the large ice-sheet margins and glaciers. DMRT-ML has thus been validated in three very different conditions: Antarctica, Barnes Ice Cap (Canada) and Canadian tundra. It has been recently used in conjunction with inverse methods to retrieve snow grain size from remote sensing data. The model is written in Fortran90 and available to the snow remote sensing community as an open-source software.

Picard, G.; Brucker, L.; Roy, A.; Dupont, F.; Fily, M.; Royer, A.

2012-11-01

182

Microwave induced center-doping of silver ions in aqueous CdS nanocrystals with tunable, impurity and visible emission.  

PubMed

Under microwave radiation, Ag(+)-doped CdS semiconductor nanocrystals with high photoluminescence quantum yield (approximately 58%) and a surprisingly large optical window (480 to 630 nm) are formed controllably using a center-doping strategy and are optimized through a green approach in pure water solution. PMID:20593082

Shen, Qihui; Liu, Yan; Xu, Jun; Meng, Changgong; Liu, Xiaoyang

2010-08-21

183

Attenuation statistics at 20.6, 31.65 and 52.85 GHz derived from emission measurements by ground-based microwave radiometers  

NASA Technical Reports Server (NTRS)

Two seasons (December 1987 to February 1988 and July 1988 to September 1988) of thermal emission measurements, taken by a multichannel ground-based microwave radiometer, are used to derive single-station zenith attenuation statistics at 20.6 and 31.65 GHz. For the summer period, statistics are also derived at 52.85 GHz. In addition, data from two radiometers located 50 km apart are used to derive two-station attenuation diversity statistics at 20.6 and 31.65 GHz. The multichannel radiometer was operated at Denver, Colorado, U.S. and the dual-channel device was operated at Platteville, Colorado. The diversity statistics are presented by cumulative distributions and by bivariate frequency distributions. The frequency distributions are analyzed when either one or both stations have liquid clouds.

Fionda, E.; Falls, M. J.; Westwater, E. R.

1991-01-01

184

Continuous-flow determination of aqueous sulfur by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry with gas-phase sample introduction  

NASA Astrophysics Data System (ADS)

A simple continuous-flow generation of volatile hydrogen sulfide and sulfur dioxide by acidification of aqueous sulfide and sulfite ions, respectively, is described for the determination of low concentrations of sulfur by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry (MIP-AES) in the normal ultraviolet (UV) and vacuum ultraviolet (VUV) regions of the spectrum. For measuring spectral lines in the VUV region, the monochromator and the enclosed external optical path between the MIP source and the entrance slit of the monochromator have both been purged with nitrogen to minimize oxygen absorption below 190 nm. Sulfur atomic emission lines at 180.73, 182.04 and 217.05 nm have been selected as the analytical lines. Of the various acids examined, 1.0 M hydrochloric acid is the most favorable for both the generation of hydrogen sulfide from sulfide ions and sulfur dioxide from sulfite ions. Either generated hydrogen sulfide or sulfur dioxide is separated from the solution in a simple gas-liquid separator and swept into the helium stream of a microwave-induced plasma for analysis. The best attainable detection limits (3 ? criterion) for sulfur at 180.73 nm were 0.13 and 1.28 ng ml -1 for the generation of hydrogen sulfide and sulfur dioxide, respectively, with the corresponding background equivalent concentrations of 20.9 and 62.2 ng ml -1 in sulfur concentration. The typical analytical working graphs obtained under the optimized experimental conditions were rectilinear over approximately four orders of magnitude in sulfur concentration. The present method has been successfully applied to the recovery test of the sulfide spiked to waste water samples and to the determination of sulfite in some samples of commercially available wine.

Nakahara, Taketoshi; Mori, Toshio; Morimoto, Satoru; Ishikawa, Hiroshi

1995-06-01

185

Environmental applications of the microwave plasma torch  

Microsoft Academic Search

One of the most important issues in environmental problem is contamination of the air by various industrial and commercial emissions. We therefore developed a portable microwave torch at atmospheric pressure by making use of magnetrons operated at the 2.45 GHz and used in a home microwave oven. This portable microwave torch is used to eliminate various air pollutants. Shoots emitted

H. S. Uhm; Y. C. Hong

2003-01-01

186

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

187

Microwave Ovens  

MedlinePLUS

... RadTown USA Topics Personal Exposure : Airport Security Scanning Cosmic Radiation During Flights X-Rays in CT Scans Dental ... Research is being done on the potential health effects from microwave exposure. It is known that microwave ...

188

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  

NASA Astrophysics Data System (ADS)

Phase-sensitive microwave interferometry and trace-rare-gas optical emission spectroscopy were used to measure the line-integrated electron density, ne, and electron temperature, Te, 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, ne 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 ne decreased quasiexponentially toward the end of the plasma column. The length of this expansion region increased with decreasing pressure, going from ˜8 cm at 5 mTorr to ˜1 cm at 50 mTorr. Te was nearly independent of the axial position in the main plasma region and strongly decreased in the expansion region at lower pressures. The Cl2 percent dissociation, ?D, obtained from the calibrated Cl2 (306 nm)-to-Xe (828 nm) emission ratio, displayed behavior similar to that of ne and Te. For example, at 5 mTorr, ?D was close to 100% near the wave launcher and ˜70% at 0.5 cm from the end of the plasma column.

Mattei, S.; Boudreault, O.; Khare, R.; Stafford, L.; Donnelly, V. M.

2011-06-01

189

Thermal microwave emissions from vegetated fields: A comparison between theory and experiment. [Agricultural Research Center, Beltsville, MD.  

NASA Technical Reports Server (NTRS)

The radiometric measurements over bare field and fields covered with grass, soybean, corn, and alfalfa were made with 1.4 GHz and 5 GHz microwave radiometers during August - October 1978. The measured results are compared with radiative transfer theory treating the vegetated fields as a two layer random medium. It is found that the presence of a vegetation cover generally gives a higher brightness temperature T(B) than that expected from a bare soil. The amount of this T(B) excess increases in the vegetation biomass and in the frequency of the observed radiation. The results of radiative transfer calculations generally match well with the experimental data, however, a detailed analysis also strongly suggests the need of incorporating soil surface roughness effect into the radiative transfer theory in order to better interpret the experimental data.

Wang, J. R.; Shiue, J.; Chuang, S. L.; Dombrowski, M.

1980-01-01

190

Analysis of regolith electromagnetic scattering as constrained by high resolution Earth-based measurements of the lunar microwave emission  

NASA Technical Reports Server (NTRS)

When high resolution measurements of the phase variation of the lunar disk center brightness temperature revealed that in situ regolith electrical losses were larger than those measured on returned samples by a factor of 1.5 to 2.0 at centimeter wavelengths, the need for a refinement of the regolith model to include realistic treatment of scattering effects was identified. Two distinct scattering regimes are considered: vertial variations in dielectric constant and volume scattering due to subsurface rock fragments. Models of lunar regolith energy transport processes are now at the state for which a maximum scientific return could be realized from a lunar orbiter microwave mapping experiment. A detailed analysis, including the effects of scattering produced a set of nominal brightness temperature spectra for lunar equatorial regions, which can be used for mapping as a calibration reference for mapping variations in mineralogy and heat flow.

Keihm, S. J.

1983-01-01

191

Electric dipole emission by fullerenes and buckyonions  

E-print Network

We study the rotation rates and electric dipole emission of hydrogenated icosahedral fullerenes (single and multishell) in various phases of the interstellar medium. Using the formalism of Draine and Lazarian for the rotational dynamics of these molecules in various astrophysical environments, we find effective rotation rates in the range 1-65 GHz with a trend toward lower rotational frequency as the radius of the molecule increases. Owing to the moderately polar nature of the C--H bond, hydrogenated fullerenes (fulleranes) are expected to have a net dipole moment and produce electric dipole radiation. Adopting the same size distribution proposed for fullerenes in the study of the UV extinction bump (2175 \\AA) we predict the dipole electric emission of mixtures of fulleranes for various levels of hydrogenation. We find that these molecules could be the carriers of the anomalous microwave emission recently detected by Watson et al. in the Perseus molecular complex.

Susana Iglesias-Groth

2005-09-15

192

Hard X-ray emission cutoff in the anomalous X-ray pulsar 4U 0142+61 detected by INTEGRAL  

NASA Astrophysics Data System (ADS)

The anomalous X-ray pulsar 4U 0142+61 has been studied with observations from INTEGRAL. The hard X-ray spectrum in the range 18-500 keV for 4U 0142+61 was derived using nearly nine years of INTEGRAL/IBIS data. We obtained the average hard X-ray spectrum of 4U 0142+61 with all available data. The spectrum of 4U 0142+61 can be fitted with a power law that includes an exponential high energy cutoff. This average spectrum is well fitted by a power law with ? ~ 0.51 ± 0.11 plus a cutoff energy at 128.6 ± 17.2 keV. The hard X-ray flux of the source from 20-150 keV showed no significant variations (within 20%) from 2003-2011. The spectral profiles have some variability over the nine years such that the photon index varies from 0.3-1.5 and the cutoff energies from 110-250 keV. The detection of the high energy cutoff around 130 keV shows some constraints on the radiation mechanisms of magnetars and possibly probes the differences between magnetar and accretion models for this special class of neutron stars. Future HXMT observations could provide stronger constraints on the hard X-ray spectral properties of this source and other magnetar candidates.

Wang, Wei; Tong, Hao; Guo, Yan-Jun

2014-06-01

193

Microwave Apexcardiography  

Microsoft Academic Search

A microwave technique for recording apexcardiograms is reported. The technique is based on detecting changes in the reflected microwaves caused by movement of the chest wall in response to left-ventricle activity. Results show that microwave technique is useful for delineating the fine structures in the precordial movement.

JAMES C. LIN; JOSEPH KIERNICKI; M. Kiernicki; P. B. Wollschlaeger

1979-01-01

194

Anomalous diffusion of pions at RHIC  

E-print Network

After pointing out the difference between normal and anomalous diffusion, we consider a hadron resonance cascade (HRC) model simulation for particle emission at RHIC and point out, that rescattering in an expanding hadron resonance gas leads to a heavy tail in the source distribution. The results are compared to recent PHENIX measurements of the tail of the particle emitting source in Au+Au collisions at RHIC. In this context, we show, how can one distinguish experimentally the anomalous diffusion of hadrons from a second order QCD phase transition.

M. Csanad; T. Csorgo; M. Nagy

2007-02-02

195

Anomalous Ferroelectric Hysteresis Loops.  

National Technical Information Service (NTIS)

Materials that exhibit anomalous ferroelectric hysteresis loops appear throughout the literature. These loops have irregular shapes that diverge from the normal hysteresis loop which is characteristic of most ferroelectrics. The observation of a unique hy...

F. J. Murdoch

1971-01-01

196

A multi-frequency measurement of thermal microwave emission from soils - The effect of soil texture and surface roughness  

NASA Technical Reports Server (NTRS)

An experiment on remote sensing of soil moisture content was conducted over bare fields with microwave radiometers at the frequencies of 1.4 GHz, 5 GHz, and 10.7 GHz during July September of 1981. Three bare fields with different surface roughneses and soil textures were prepared for the experiment. Ground truth acquisition of soil temperatures and moisture contents for 5 layers down to the depth of 15 cm was made concurrently with radiometric measurements. The experimental results show that the effect of surface roughness is to increase the soils' brightness temperature and to reduce the slope of regression between brightness temperature and moisture content. The slopes of regression for soils with different textures are found to be comparable, and the effect of soil texture is reflected in the difference of regression line intercepts at brightness temperature axis. The result is consistent with laboratory measurement of soils' dielectric permittivity. Measurements on wet smooth bare fields give lower brightness temperatures at 5 GHz than at 1.4 GHz. Previously announced in STAR as N82-24550

Wang, J. R.; Oneill, P. E.; Jackson, T. J.; Engman, E. T.

1982-01-01

197

A multi-frequency measurement of thermal microwave emission from soils: The effects of soil texture and surface roughness  

NASA Technical Reports Server (NTRS)

An experiment on remote sensing of soil moisture content was conducted over bare fields with microwave radiometers at the frequencies of 1.4 GHz, 5 GHz, and 10.7 GHz during July - September of 1981. Three bare fields with different surface roughnesses and soil textures were prepared for the experiment. Ground truth acquisition of soil temperatures and moisture contents for 5 layers down to the depths of 15 cm was made concurrently with radiometric measurements. The experimental results show that the effect of surface roughness is to increase the soils' brightness temperature and to reduce the slope of regression between brightness temperature and moisture content. The slopes of regression for soils with different textures are found to be comparable, and the effect of soil texture is reflected in the difference of regression line intercepts at brightness temperature axis. The result is consistent with laboratory measurement of soils' dielectric permittivity. Measurements on wet smooth bare fields give lower brightness temperatures at 5 GHz than at 1.4 GHz.

Wang, J. R.; Oneill, P. E.; Jackson, T. J.; Engman, E. T. (principal investigators)

1981-01-01

198

An Ocean Wave Spectrum Derived from Polarimetric Microwave Radiometer Data  

Microsoft Academic Search

Oceanic emission and scattering model is critical in remote sensing wind vector using passive polarimetric microwave radiometer (1, 2). This paper presents a detailed analysis of a simplified Two-Scale Model for ocean surface polarimetric microwave emission and derives an ocean wave spectrum from polarimetric microwave radiometer data. The two-scale model states that brightness temperatures observed by a radiometer at observation

Xiaobin Yin; Zhenzhan Wang; Lei Han; Qing Xu

2008-01-01

199

Anomalous is ubiquitous  

SciTech Connect

Brownian motion is widely considered the quintessential model of diffusion processes-the most elemental random transport processes in Science and Engineering. Yet so, examples of diffusion processes displaying highly non-Brownian statistics-commonly termed 'Anomalous Diffusion' processes-are omnipresent both in the natural sciences and in engineered systems. The scientific interest in Anomalous Diffusion and its applications is growing exponentially in the recent years. In this Paper we review the key statistics of Anomalous Diffusion processes: sub-diffusion and super-diffusion, long-range dependence and the Joseph effect, Levy statistics and the Noah effect, and 1/f noise. We further present a theoretical model-generalizing the Einstein-Smoluchowski diffusion model-which provides a unified explanation for the prevalence of Anomalous Diffusion statistics. Our model shows that what is commonly perceived as 'anomalous' is in effect ubiquitous. - Highlights: > The article provides an overview of Anomalous Diffusion (AD) statistics. > The Einstein-Smoluchowski diffusion model is extended and generalized. > The generalized model universally generates AD statistics. > A unified 'universal macroscopic explanation' for AD statistics is established. > AD statistics are shown to be fundamentally connected to robustness.

Eliazar, Iddo, E-mail: eliazar@post.tau.ac.il [Department of Technology Management, Holon Institute of Technology, P.O. Box 305, Holon 58102 (Israel); Klafter, Joseph, E-mail: klafter@post.tau.ac.il [School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

2011-09-15

200

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

E-print Network

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 $\\sim$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; Brown, G V; Kelley, R L; Kilbourne, C A; Porter, F S

2010-01-01

201

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

NASA Technical Reports Server (NTRS)

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 two 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.; Beiersdorfer, P.; Brown, G. V.; Kelley, R. L.; Porter, F. S.

2010-01-01

202

Microwave-promoted pure host phase for red emission CaS:Eu2+ phosphor from single CaSO4 precursor and the photoluminescence property  

NASA Astrophysics Data System (ADS)

We report a novel approach to obtaining a classical blue-green excitable CaS:Eu2+ phosphor with desired red emission by microwave (MW) firing procedure in the absence of adding elemental sulphur. The disturbing effect of MW electromagnetic field on decomposition of CaSO4 into CaS activated by europium is distinctly observed to give pure host phase without adding any elemental sulphur and carbon. The host phase evolution is observed to be highly dependent on the variation of applied MW power from X-ray diffraction (XRD) patterns and the corresponding photoluminescence (PL), and a maximum PL intensity at 1100 W of MW power is acquired for the obtained purer host phase. The non-thermal and non-equilibrium effects by MW are revealed to correlate with the interaction between polar structure of the host and applied electromagnetic field. The results demonstrate an optional procedure to prepare this red-emitting phosphor in an effective, environment-friendly and scalable approach for phosphor production in the application of bio-illumination for plant cultivation and artificial photosynthesis.

Ma, Jian; Lu, Qi-Fei; Wang, Yan-Ze; Lu, Zhi-Juan; Sun, Liang; Dong, Xiao-Fei; Wang, Da-Jian

2014-08-01

203

Growth, microstructure, and field-emission properties of synthesized diamond film on adamantane-coated silicon substrate by microwave plasma chemical vapor deposition  

SciTech Connect

Diamond nucleation on unscratched Si surface is great importance for its growth, and detailed understanding of this process is therefore desired for many applications. The pretreatment of the substrate surface may influence the initial growth period. In this study, diamond films have been synthesized on adamantane-coated crystalline silicon {l_brace}100{r_brace} substrate by microwave plasma chemical vapor deposition from a gaseous mixture of methane and hydrogen gases without the application of a bias voltage to the substrates. Prior to adamantane coating, the Si substrates were not pretreated such as abraded/scratched. The substrate temperature was {approx}530 deg. C during diamond deposition. The deposited films are characterized by scanning electron microscopy, Raman spectrometry, x-ray diffraction, and x-ray photoelectron spectroscopy. These measurements provide definitive evidence for high-crystalline quality diamond film, which is synthesized on a SiC rather than clean Si substrate. Characterization through atomic force microscope allows establishing fine quality criteria of the film according to the grain size of nanodiamond along with SiC. The diamond films exhibit a low-threshold (55 V/{mu}m) and high current-density (1.6 mA/cm{sup 2}) field-emission (FE) display. The possible mechanism of formation of diamond films and their FE properties have been demonstrated.

Tiwari, Rajanish N.; Chang Li [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan 300 (China)

2010-05-15

204

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

205

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

206

Polarized synchrotron emission  

E-print Network

Galactic synchrotron emission represents the most relevant foreground contamination in cosmic microwave background (CMB) anisotropy observations at angular scales $\\theta \\gsim 1^\\circ$ and frequencies $\

Carlo Burigana; Laura La Porta; Wolfgang Reich; Patricia Reich; Joaquin Gonzalez-Nuevo; Marcella Massardi; Gianfranco De Zotti

2006-07-20

207

Burst and Persistent Emission Properties during the Recent Active Episode of the Anomalous X-Ray Pulsar 1E 1841-045  

NASA Technical Reports Server (NTRS)

SWift/BAT detected the first burst from 1E 1841-045 in May 2010 with intermittent burst activity recorded through at least July 2011. Here we present Swift and Fermi/GBM observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T90 durations of the bursts range between 18 - 140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8-25) x 1038 erg, which is in the low side of SGR 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 IE 1841-045 might not involve large scale restructuring (either crustal or magnetospheric) as seen in other magnetar sources.

Lin, Lin; Kouveliotou, Chryssa; Gogus, Ersin; van der Horst, Alexander J.; Watts, Anna L.; Baring, Matthew G.; Kaneko, Yuki; Wijers, Ralph A. M. J.; Woods, Peter M.; Barthelmy, Scott; Burgess, J. Michael; Chaplin, Vandiver; Gehrels, Neil; Goldstein, Adam; Granot, Jonathan; Guiriec, Sylvain; Mcenery, Julie; Preece, Robert D.; Tierney, David; van der Klis, Michiel; von Kienlin, Andreas; Zhang, Shuang Nan

2011-01-01

208

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

209

Modeling microwave/electron-cloud interaction  

E-print Network

Starting from the separate codes BI-RME and ECLOUD or PyECLOUD, we are developing a novel joint simulation tool, which models the combined effect of a charged particle beam and of microwaves on an electron cloud. Possible applications include the degradation of microwave transmission in tele-communication satellites by electron clouds; the microwave-transmission tecchniques being used in particle accelerators for the purpose of electroncloud diagnostics; the microwave emission by the electron cloud itself in the presence of a magnetic field; and the possible suppression of electron-cloud formation in an accelerator by injecting microwaves of suitable amplitude and frequency. A few early simulation results are presented.

Mattes, M; Zimmermann, F

2013-01-01

210

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

211

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

212

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

213

Anomalous Muonium in Silicon  

Microsoft Academic Search

The anomalous muonium state in Si has been studied with the muon-spin rotation technique as a function of the strength and orientation of the applied magnetic field. It was found that this state is well described by a spin Hamiltonian with axial symmetry about a [111] axis.

B. D. Patterson; A. Hintermann; W. Kuendig; P. F. Meier; F. Waldner; H. Graf; E. Recknagel; A. Weidinger; Th. Wichert

1978-01-01

214

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

215

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

216

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

217

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

218

Anomalous radiative transitions  

E-print Network

Anomalous transitions involving photons derived by many-body interaction of the form, $\\partial_{\\mu} G^{\\mu}$, in the standard model are studied. This does not affect the equation of motion in the bulk, but makes wave functions modified, and causes the unusual transition characterized by the time-independent probability. In the transition probability at a time-interval $T$ expressed generally in the form $P=T \\Gamma_0 +P^{(d)}$, now with $ P^{(d)} \

Kenzo Ishikawa; Toshiki Tajima; Yutaka Tobita

2014-09-15

219

Microwave remote sensing of soil moisture: elimination of texture effect  

Microsoft Academic Search

In view of the influence of soil texture on microwave radiation, an attempt is made to eliminate the textural effects on the microwave reflectivity\\/emission. To determine the appropriate soil moisture parameter that minimizes the textural influences on microwave radiation from soils, soil moisture is expressed in terms of gravimetric and volumetric units and percentage of field capacity (Mfc ) and

P. V. N. Rao; C. S. Raju; K. S. Rao

1990-01-01

220

The anomalous extinction law  

NASA Astrophysics Data System (ADS)

The results of the calculations of anomalous interstellar extinction laws characterized by different values of the ratio of the total to selective extinction are presented. The calculation is based on the Mie theory of light scattering by small particles assuming a two-grain dust model of Mathis et al. (1977) and by adopting their particle size distribution, in which the minimum and maximum size is taken to be 0.005 and 0.22 micron, respectively. Furthermore, dielectric functions for both the graphite- and 'astronomical silicate'-type grains are used, as derived by Draine and Lee (1984). Following Mathis and Wallenhorst (1981), the anomalous extinction laws are then obtained by changing the upper size cutoff of the particles. A comparison shows that the calculated anomalous extinction laws agree quite well with the laws observationally derived using the color-difference method. A trial-and-error method for the determination of the law, based on a comparison of the observed extinction-free spectral energy distribution with the corresponding theoretical Kurucz (1979) model, is explained.

Steenman, H.; The, P. S.

1989-09-01

221

Anomalous Diffusion Near Resonances  

SciTech Connect

Synchro-betatron resonances can lead to emittance growth and the loss of luminosity. We consider the detailed dynamics of a bunch near such a low order resonance driven by crossing angles at the collision points. We characterize the nature of diffusion and find that it is anomalous and sub-diffusive. This affects both the shape of the beam distribution and the time scales for growth. Predictions of a simplified anomalous diffusion model are compared with direct simulations. Transport of particles near resonances is still not a well understood phenomenon. Often, without justification, phase space motion is assumed to be a normal diffusion process although at least one case of anomalous diffusion in beam dynamics has been reported [1]. Here we will focus on the motion near synchro-betatron resonances which can be excited by several means, including beams crossing at an angle at the collision points as in the LHC. We will consider low order resonances which couple the horizontal and longitudinal planes, both for simplicity and to observe large effects over short time scales. While the tunes we consider are not practical for a collider, nonetheless the transport mechanisms we uncover are also likely to operate at higher order resonances.

Sen, Tanaji; /Fermilab

2010-05-01

222

Emissions and photocatalytic selectivity of SrWO4:Ln3+ (Eu3+, Tb3+, Sm3+ and Dy3+) prepared by a supersonic microwave co-assistance method.  

PubMed

The chemical effects of high intensity ultrasound and microwave irradiation on lanthanide (Eu(3+), Tb(3+), Sm(3+) and Dy(3+)) activated SrWO(4) phosphors were extensively studied. Four classes of characteristic optically active materials (red, green, orange-red and blue-yellow) with striking luminescence were facilely prepared under very low temperature (70 °C) in 45 min. Particularly, Sm(3+), Dy(3+) and Eu(3+) doped strontium tungstates were visible-light driven emissive. The photocatalytic properties of these luminescent lanthanide doped tungstates were systematically examined by investigating the degradation behavior of different dyes. PMID:22854656

Zheng, Yuhui; Lin, Jintai; Wang, Qianming

2012-10-01

223

Explosive Emission Cathode Based on a Carbon Fiber for Long-Term Pulsed-Periodic Mode of Operation and its Application in a High-Power Microwave Pulse Generator Without External Magnetic Field  

NASA Astrophysics Data System (ADS)

Current characteristics and operating lifetime of the explosive emission cathode based on a carbon microfiber are investigated in the pulsed-periodic mode of operation with pulse duration of about 5 ns. Long-term (for up to 3.6 million pulses) tests of the cathode operating lifetime are carried out. Specific ablation of the fiber material equal to 2.4·10-4 g/C is obtained. Change in the morphology of the fiber surface during long-time operation caused by deposition of carbon from the cathode plasma is revealed. The microscopic electric field strength on the fiber surface is estimated taking into account the surface microrelief. The efficiency of microwave generation comparable with that of a velvet cathode in low (200 kV/cm) average electric field in the gap is obtained for the Cherenkov microwave generator with vacuum diode without external magnetic field of decimeter wavelength range based on the SINUS-7 pulsed-periodic high-current electron accelerator with current pulse duration of 50 ns. The operating lifetime no less than 105 pulses is demonstrated for the carbon fiber-based cathode of the microwave generator operating in the mode of pulse batch with duration of several seconds and pulse repetition frequency of 20-50 Hz.

Kutenkov, O. P.; Pegel, I. V.; Totmeninov, E. M.

2014-09-01

224

A new microwave spectroscope  

E-print Network

A NEW MICROWAVE SPECTROSCOPE A Dissertation By Andrew E. Sail* June 1951 Approved as to style and content by Chairman of Com ttee A NEW MICROWAVE SPECTROSCOPE A Dissertation Submitted to the Faculty of the Agricultural and Mechanical.... THEORETICAL APPROACH TO THE DESIGNING OP A MICROWAVE SPECTROSCOPE .................... 7 III. DESIGN OF THE EXPERIMENTAL MICROWAVE SPECTROSCOPE .......................... 14 Microwave Source .............................. 17 Microwave Circuit...

Salis, Andrew E.

2013-10-04

225

A New Neural Network Approach Including First-Guess for Retrieval of Atmospheric Water Vapor, Cloud Liquid Water Path, Surface Temperature and Emissivities Over Land From Satellite Microwave Observations  

NASA Technical Reports Server (NTRS)

The analysis of microwave observations over land to determine atmospheric and surface parameters is still limited due to the complexity of the inverse problem. Neural network techniques have already proved successful as the basis of efficient retrieval methods for non-linear cases, however, first-guess estimates, which are used in variational methods to avoid problems of solution non-uniqueness or other forms of solution irregularity, have up to now not been used with neural network methods. In this study, a neural network approach is developed that uses a first-guess. Conceptual bridges are established between the neural network and variational methods. The new neural method retrieves the surface skin temperature, the integrated water vapor content, the cloud liquid water path and the microwave surface emissivities between 19 and 85 GHz over land from SSM/I observations. The retrieval, in parallel, of all these quantities improves the results for consistency reasons. A data base to train the neural network is calculated with a radiative transfer model and a a global collection of coincident surface and atmospheric parameters extracted from the National Center for Environmental Prediction reanalysis, from the International Satellite Cloud Climatology Project data and from microwave emissivity atlases previously calculated. The results of the neural network inversion are very encouraging. The r.m.s. error of the surface temperature retrieval over the globe is 1.3 K in clear sky conditions and 1.6 K in cloudy scenes. Water vapor is retrieved with a r.m.s. error of 3.8 kg/sq m in clear conditions and 4.9 kg/sq m in cloudy situations. The r.m.s. error in cloud liquid water path is 0.08 kg/sq m . The surface emissivities are retrieved with an accuracy of better than 0.008 in clear conditions and 0.010 in cloudy conditions. Microwave land surface temperature retrieval presents a very attractive complement to the infrared estimates in cloudy areas: time record of land surface temperature will be produced.

Aires, F.; Prigent, C.; Rossow, W. B.; Rothstein, M.; Hansen, James E. (Technical Monitor)

2000-01-01

226

Improvement of the emission properties from InGaN/GaN dot-in-a-wire nanostructures after treatment in the flowing afterglow of a microwave N2 plasma  

NASA Astrophysics Data System (ADS)

Nominally pure GaN nanowires (NWs) and InGaN/GaN dot-in-a-wire heterostructures were exposed to the flowing afterglow of a N2 microwave plasma and characterized by photoluminescence (PL) spectroscopy. While the band-edge emission from GaN NWs and the GaN matrix of the InGaN/GaN NWs strongly decreased due to the creation of non-radiative recombination centers in the near-surface region, the emission from the InGaN dots strongly increased. PL excitation measurements indicate that such an increase cannot be explained by a plasma-induced shift of the GaN absorption edge. It is rather ascribed to the passivation of grown-in defects and dynamic annealing due to the presence of plasma-generated N atoms and N2 metastables without excessive introduction of ion-induced damage.

Afonso Ferreira, J.; Nguyen, H. P. T.; Mi, Z.; Leonelli, R.; Stafford, L.

2014-10-01

227

Improvement of the emission properties from InGaN/GaN dot-in-a-wire nanostructures after treatment in the flowing afterglow of a microwave N2 plasma.  

PubMed

Nominally pure GaN nanowires (NWs) and InGaN/GaN dot-in-a-wire heterostructures were exposed to the flowing afterglow of a N2 microwave plasma and characterized by photoluminescence (PL) spectroscopy. While the band-edge emission from GaN NWs and the GaN matrix of the InGaN/GaN NWs strongly decreased due to the creation of non-radiative recombination centers in the near-surface region, the emission from the InGaN dots strongly increased. PL excitation measurements indicate that such an increase cannot be explained by a plasma-induced shift of the GaN absorption edge. It is rather ascribed to the passivation of grown-in defects and dynamic annealing due to the presence of plasma-generated N atoms and N2 metastables without excessive introduction of ion-induced damage. PMID:25299752

Ferreira, J Afonso; Nguyen, H P T; Mi, Z; Leonelli, R; Stafford, L

2014-10-31

228

Microwave remote sensing of soil moisture  

NASA Technical Reports Server (NTRS)

Knowledge of soil moisture is important to many disciplines, such as agriculture, hydrology, and meteorology. Soil moisture distribution of vast regions can be measured efficiently only with remote sensing techniques from airborne or satellite platforms. At low microwave frequencies, water has a much larger dielectric constant than dry soil. This difference manifests itself in surface emissivity (or reflectivity) change between dry and wet soils, and can be measured by a microwave radiometer or radar. The Microwave Sensors and Data Communications Branch is developing microwave remote sensing techniques using both radar and radiometry, but primarily with microwave radiometry. The efforts in these areas range from developing algorithms for data interpretation to conducting feasibility studies for space systems, with a primary goal of developing a microwave radiometer for soil moisture measurement from satellites, such as EOS or the Space Station. These efforts are listed.

Shiue, J. C.; Wang, J. R.

1988-01-01

229

Microwave interconnection  

NASA Astrophysics Data System (ADS)

A limited evaluation was made of two commonly found microwave interconnections: microstrip-to-microstrip and coaxial-to-microstrip. The evaluation attempted to select the interconnection technique which worked best for the particular interface type. Short ribbon wires worked best for the microstrip-to-microstrip interconnection. A published method of compensating the microstrip conductor had the best performance for the coaxial-to-microstrip interconnection. The work was conducted under the Microwave Technology Process Capability Assurance Program at Allied-Signal Inc., Kansas City Division.

Fry, P. E.

1993-06-01

230

Optical emission spectroscopy of the plasma during microwave CVD of diamond thin films with nitrogen addition and relation to the thin film morphology  

Microsoft Academic Search

It is common knowledge that the presence of gas impurities such as nitrogen during microwave plasma assisted chemical vapour deposition of diamond can drastically affect the film morphology and even favour the growth of oriented textured films. It was shown previously that diamond films could be grown with various preferred orientations depending on the fraction of nitrogen present in the

T. Vandevelde; M Nesladek; C Quaeyhaegens; L Stals

1997-01-01

231

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

232

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

2012-01-01

233

Microwave industry outlook - overview  

Microsoft Academic Search

This paper reviews the influences that will shape the future of the microwave industry covering such topics as defense, engineering education, future of microwaves, healthcare, history of microwaves, technology roadmaps and telecommunications

Peter Staecker

2002-01-01

234

Microwave processing of ceramics  

SciTech Connect

This paper discusses the following topics on microwave processing of ceramics: Microwave-material interactions; anticipated advantage of microwave sintering; ceramic sintering; and ceramic joining. 24 refs., 4 figs. (LSP)

Katz, J.D.

1989-01-01

235

X-ray Anomalous Scattering  

NSDL National Science Digital Library

This University of Washington Web site "is intended to serve both as an introductory tutorial to anomalous scattering and as a general tool for designing experiments based on anomalous scattering." Visitors can find a periodic table and a chart supplying X-ray absorption edge data. Students needing assistance with the concept of anomalous scattering will find the tutorial explaining the interactions of incident photons having relatively high and low energy with scattering electrons very instructive. The site also supplies users with information about Friedel's Law and MAD experiments.

236

Compact Microwave Fourier Spectrum Analyzer  

NASA Technical Reports Server (NTRS)

A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.

Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

2009-01-01

237

Applications of Microwaves to Remote Sensing  

Microsoft Academic Search

Extensive theoretical studies as well as laboratory and field measurements of rough-surface scattering and emission from agricultural soil and sea surface and of volume scattering and emission from snow and vegetation yield a considerable comprehension of the interaction of microwaves with the molecular properties and the geometrical features of these media. Hence algorithms have been derived which allow the interpretation

Erwin Schanda

1987-01-01

238

A microwave plasma torch and its applications  

NASA Astrophysics Data System (ADS)

A portable microwave plasma torch at atmospheric pressure by making use of magnetrons operated at 2.45 GHz and used in a home microwave oven has been developed. This electrodeless torch can be used in various areas including commercial, environmental and military applications. For example, perfluorocompounds (PFCs), which have long lifetimes and serious global warming implications, are widely used during plasma etching and plasma-assisted chamber cleaning processes in chemical vapour deposition systems. The microwave torch effectively eliminates PFCs. Efficient decomposition of toluene gas indicates the effectiveness of volatile organic compound eliminations from industrial emission and the elimination of airborne chemical and biological warfare agents. The microwave torch has been used to synthesize carbon nanotubes in an on-line system, thereby providing the opportunity of mass production of the nanotubes. There are other applications of the microwave plasma torch.

Uhm, H. S.; Hong, Y. C.; Shin, D. H.

2006-05-01

239

Tandem microwave waste remediation and decontamination system  

DOEpatents

The invention discloses a tandem microwave system consisting of a primary chamber in which microwave energy is used for the controlled combustion of materials. A second chamber is used to further treat the off-gases from the primary chamber by passage through a susceptor matrix subjected to additional microwave energy. The direct microwave radiation and elevated temperatures provide for significant reductions in the qualitative and quantitative emissions of the treated off gases. The tandem microwave system can be utilized for disinfecting wastes, sterilizing materials, and/or modifying the form of wastes to solidify organic or inorganic materials. The simple design allows on-site treatment of waste by small volume waste generators.

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

1999-01-01

240

The physics of anomalous glue  

E-print Network

We give a brief overview of the physics of gluonic degrees of freedom associated with the strong (QCD) axial anomaly. The role of this anomalous glue in the spin structure of the proton and eta'-hadron interactions is discussed.

Steven D. Bass

2001-12-07

241

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

242

Anomalous Dynamics of Translocation  

E-print Network

We study the dynamics of the passage of a polymer through a membrane pore (translocation), focusing on the scaling properties with the number of monomers $N$. The natural coordinate for translocation is the number of monomers on one side of the hole at a given time. Commonly used models which assume Brownian dynamics for this variable predict a mean (unforced) passage time $\\tau$ that scales as $N^2$, even in the presence of an entropic barrier. However, the time it takes for a free polymer to diffuse a distance of the order of its radius by Rouse dynamics scales with an exponent larger than 2, and this should provide a lower bound to the translocation time. To resolve this discrepancy, we perform numerical simulations with Rouse dynamics for both phantom (in space dimensions $d=1$ and 2), and self-avoiding (in $d=2$) chains. The results indicate that for large $N$, translocation times scale in the same manner as diffusion times, but with a larger prefactor that depends on the size of the hole. Such scaling implies anomalous dynamics for the translocation process. In particular, the fluctuations in the monomer number at the hole are predicted to be non-diffusive at short times, while the average pulling velocity of the polymer in the presence of a chemical potential difference is predicted to depend on $N$.

Jeffrey Chuang; Yacov Kantor; Mehran Kardar

2001-08-17

243

Anomalous cosmic rays  

NASA Astrophysics Data System (ADS)

Anomalous cosmic rays (ACRs) first started showing up in observations 40 years ago. Within a few years a paradigm was developed to explain their origin: they begin their life as interstellar neutral atoms that drift into the heliosphere, become singly ionized by chargeexchange with a solar wind ion or by photoionization, are picked up by the expanding solar wind, and accelerated to the observed energies by diffusive shock acceleration at the solar wind termination shock. This paradigm became widely accepted and withstood the tests of further observations until 16 December 2004, when Voyager 1 crossed the termination shock and didn't find their source. In August 2007, Voyager 2 crossed the termination shock and also did not find the source location of ACRs. Clearly, the source location was not at the termination shock where the two Voyagers crossed. Alternative models have been proposed with acceleration elsewhere on the shock or by other acceleration processes in the heliosheath. We discuss the latest observations of ACRs from the Voyager spacecraft and hopefully shed more light on this ongoing puzzle.

Cummings, Alan C.; Stone, Edward C.

2013-02-01

244

Wideband Agile Digital Microwave Radiometer  

NASA Technical Reports Server (NTRS)

The objectives of this work were to take the initial steps needed to develop a field programmable gate array (FPGA)- based wideband digital radiometer backend (>500 MHz bandwidth) that will enable passive microwave observations with minimal performance degradation in a radiofrequency-interference (RFI)-rich environment. As manmade RF emissions increase over time and fill more of the microwave spectrum, microwave radiometer science applications will be increasingly impacted in a negative way, and the current generation of spaceborne microwave radiometers that use broadband analog back ends will become severely compromised or unusable over an increasing fraction of time on orbit. There is a need to develop a digital radiometer back end that, for each observation period, uses digital signal processing (DSP) algorithms to identify the maximum amount of RFI-free spectrum across the radiometer band to preserve bandwidth to minimize radiometer noise (which is inversely related to the bandwidth). Ultimately, the objective is to incorporate all processing necessary in the back end to take contaminated input spectra and produce a single output value free of manmade signals to minimize data rates for spaceborne radiometer missions. But, to meet these objectives, several intermediate processing algorithms had to be developed, and their performance characterized relative to typical brightness temperature accuracy re quirements for current and future microwave radiometer missions, including those for measuring salinity, soil moisture, and snow pack.

Gaier, Todd C.; Brown, Shannon T.; Ruf, Christopher; Gross, Steven

2012-01-01

245

Electron kinetics inferred from observations of microwave bursts during edge localised modes in the Mega-Amp Spherical Tokamak  

E-print Network

Recent measurements of microwave and X-ray emission during edge localised mode (ELM) activity in tokamak plasmas provide a fresh perspective on ELM physics. It is evident that electron kinetics, which are not incorporated in standard (fluid) models for the instability that drives ELMs, play a key role in the new observations. These effects should be included in future models for ELMs and the ELM cycle. The observed radiative effects paradoxically imply acceleration of electrons parallel to the magnetic field combined with rapid acquisition of perpendicular momentum. It is shown that this paradox can be resolved by the action of the anomalous Doppler instability which enables fast collective radiative relaxation, in the perpendicular direction, of electrons accelerated in the parallel direction by inductive electric fields generated by the initial ELM instability.

Freethy, S J; Chapman, S C; Dendy, R O; Lai, W N; Pamela, S J P; Shevchenko, V F; Vann, R G L

2014-01-01

246

Speciation analysis of triethyl-lead and tributyl-tin compounds in human urine by liquid-liquid extraction and gas chromatography microwave-induced plasma atomic emission detection.  

PubMed

This work describes the development of a fast method for speciation analysis of triethyl-lead and tributyl-tin species in urine samples after in situ derivatization by tetraethyl- or tetrapropyl-borate reagents. The alkylation reaction is done in the aqueous and urine medium and the less-polar derivatives are extracted in hexane by liquid-liquid extraction. The species were extracted and the extract was efficiently collected from the aqueous phase after centrifugation. Finally, the organometallic species are separated by gas chromatography and determined from the emission signals of elemental lead and tin. Atomic lead and tin are formed from the organolead and organotin compounds during atomization of the column eluate in a microwave-induced helium plasma source. The simultaneous measurement of lead (Pb) at 405.780 nm and tin (Sn) at 303.419 nm was achieved by an atomic emission detector. Finally, the analytes were determined with satisfactory precision (<5%) and detection limits of 0.05 ?g Pb/L and 0.48 ?g Sn/L, respectively, when 10 mL of urine is extracted with 1 mL of hexane and 1 ?L of extract is injected. PMID:22689489

Zachariadis, George A; Rosenberg, Erwin

2012-05-01

247

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

248

Anomalous absorption in H_{2}CO molecule  

NASA Astrophysics Data System (ADS)

Formaldehyde (H_2CO) is the first organic molecule identified in a number of galactic and extragalactic radio sources through its transition 1_{10}-1_{11} at 4.830 GHz in absorption in 1969. Later on, this transition was found in anomalous absorption. In some cosmic objects, this transition however was found in emission and even as a maser radiation. Since the transition 1_{10}-1_{11} of ortho-H_2CO is considered as a unique probe of high density gas at low temperature, the study of H_2CO has always been of great importance for astrophysicists as well as for spectroscopists. In the present investigation, we have solved a set of statistical equilibrium equations coupled with the equations of radiative transfer for H_2CO. Since the kinetic temperature in the medium where H_2CO is identified is few tens of Kelvin, we have considered 22 rotational levels of ortho-H_2CO in the ground vibrational and ground electronic states. The input data required in the present investigation are the radiative transition probabilities and the collisional rates. Using the latest data for radiative transition probabilities and the collisional rates, we have found anomalous absorption of 1_{10}-1_{11}, 2_{11}-2_{12} and 3_{12} - 3_{13} transitions of ortho-H_2CO.

Sharma, Monika; Kumar Sharma, Mohit

249

Anomalous transport with overlap fermions  

E-print Network

Anomalous correlators of vector and axial currents which enter the Kubo formulae for the chiral magnetic and the chiral separation conductivities are explicitly calculated for free overlap fermions on the lattice. The results are confronted with continuum calculations in the finite-temperature regularization, and a subtle point of such regularization for chiral magnetic conductivity related to the correct counting of the chiral states is highlighted. In agreement with some previous claims in the literature, we find that in a lattice regularization which respects gauge invariance, the chiral magnetic conductivity vanishes. We point out that the relation of anomalous transport coefficients to axial anomaly is nontrivial due to the non-commutativity of their infrared limit and the Taylor expansion in baryon or chiral chemical potential. In particular, we argue that the vector and axial Ward identities fix the asymptotic behavior of anomalous current-current correlators in the limit of large momenta. Basing on the work of Knecht et al. on the perturbative non-renormalization of the transverse part of the correlator of two vector and one axial currents, we demonstrate that the relation of the anomalous vector-vector correlator to axial anomaly holds perturbatively in massless QCD but might be subject to non-perturbative corrections. Finally, we identify kinematical regimes in which the anomalous transport coefficients can be extracted from lattice measurements.

P. V. Buividovich

2013-12-06

250

The potential of microwave radiometers in monitoring forest biomass  

Microsoft Academic Search

Forest biomass is an important factor in the flux of atmospheric CO2 and its potential impact on global climatic change. In this study a mathematical evaluation of the potential of microwave radiometers for monitoring forest biomass is carried out. For this purpose, a microwave emission model is developed using the iterative solution of the radiative transfer equation to relate the

Mostafa A. Karam

1994-01-01

251

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

252

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

253

Effect of Spatial Scale on Soil Moisture Retrieval From Passive Microwave Sensors  

E-print Network

Effect of Spatial Scale on Soil Moisture Retrieval From Passive Microwave Sensors Panciera, R. 1 simulate the microwave emission from the earth surface given a specified soil water content, soil@civenv.unimelb.edu.au Keywords: Remote sensing, passive microwave, soil moisture, scaling EXTENDED ABSTRACT Near-surface soil

Walker, Jeff

254

Microwave radiometer measurements at Liquid water path algorithm development and accuracy  

E-print Network

1 Microwave radiometer measurements at Chilbolton Liquid water path algorithm development Project Report #12;2 CONTENTS 1. INTRODUCTION. 1.1Liquid water clouds 1.2Microwave emission from the atmosphere 1.3Liquid water path retrieval 2. MICROWAVE RADIOMETERS. 2.1Radiometer description. 2.2 Radiometer

Reading, University of

255

HARD X-RAY AND MICROWAVE OBSERVATIONS OF MICROFLARES Jiong Qiu,1, 2  

E-print Network

V and microwave emission at around 10 GHz. Spectral analysis in these two wavelengths corroborates the nonthermalHARD X-RAY AND MICROWAVE OBSERVATIONS OF MICROFLARES Jiong Qiu,1, 2 Chang Liu,2 Dale E. Gary,2 Gelu, we study solar microflares using the coordinated hard X-ray and microwave observations obtained

Qiu, Jiong

256

Tracking Jupiter at microwave frequencies after the 2009 impact  

NASA Astrophysics Data System (ADS)

On 19 July 2009, amateur astronomer Anthony Wesley located near Canberra, Australia, discovered an anomalous dark feature near Jupiter's south pole. It was soon confirmed with additional observations that the new feature was an impact site created by an unknown object. The only other observed collision with Jupiter occurred 15 years earlier with the catastrophic impact of the Shoemaker-Levy 9 Comet (SL9). Unlike the well-predicted SL9 event, the biggest question to answer this time is whether the impact body was a comet or an asteroid. We started a campaign to track Jupiter at microwave frequencies with NASA's Deep Space Network (DSN), in Canberra, Goldstone (California), and Madrid, and the Allen Telescope Array (ATA) in California. A 34m DSN radio telescope at Goldstone was operated by students through GAVRT program. Our primary goal was first to detect molecular radio emissions possibly originating from cometary core components, such as OH, H2O, and NH3, and second to detect radio burst in non-thermal continuum emissions, as observed after the SL-9 impact 15 years ago. We used a 70m radio telescope in Canberra and another 70m in Madrid to search for molecular emissions at 1.6 GHz for OH, 22 GHz for water vapors, 23 GHz for ammonia. Several radio spectroscopy observing sessions have been successfully conducted from 23 July to 1 August. We also started continuum emission monitoring, mainly at 2.3 GHz and 8.4 GHz using 34m and 70m DSN telescopes and the ATA. At early stage of this still on-going monitoring, joint observations were conducted with two 34m telescopes in Canberra and the ATA on 30 July and 9 August in order to have long continuous time coverage and to check flux density scales using a common calibrator source. To highlight this campaign, on 22 November we undertook the Jupiter: Project 24 for the International Year of Astronomy. This campaign was over 24 hours of continuous observation of Jupiter using all three DSN complexes around the world. A couple of DSN 34m telescopes were operated by students organized by two educational programs: GAVRT in California and PARTNeR in Madrid. The Jupiter: Project 24 observations were broadcasted to the world in real time via the Internet. In this talk, we will present a summary of results from the molecular emission search and the continuum flux density monitoring. The evolution of the non-thermal Jupiter radio emission after the July 2009 impact will be discussed, along with a comparison to the increase in the synchrotron radiation caused by the SL9 impact in 1994.

Horiuchi, Shinji; García-Miró, Cristina; Rizzo, Ricardo; Forster, James; Hofstadter, Mark; Dorcey, Ryan; Jauncey, David; de Pater, Imke; Baines, Graham; Sotuela, Ioanna

2010-05-01

257

Plane-mirroring anomaly in the cosmic microwave background maps  

E-print Network

The plane-mirror symmetry previously noticed in the Cosmic Microwave Background (CMB) temperature anisotropy maps of Wilkinson Microwave Anisotropy Probe is shown to possess certain anomalous properties. The degree of the randomness determined by the Kolmogorov stochasticity parameter in the both symmetry regions appears to have identical values which, however, essentially differ from the corresponding values for other sky regions. If the mirroring were of cosmological origin, this would imply either additional randomizing properties in those directions of the Universe or their different line-of-sight depth. This analysis also provides a way to test the hypothesis of a link between the nature of dark energy and inhomogeneities.

V. G. Gurzadyan; T. Ghahramanyan; A. L. Kashin; H. G. Khachatryan; A. A. Kocharyan; H. Kuloghlian; D. Vetrugno; G. Yegorian

2009-03-19

258

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

259

Anomalous-viscosity current drive  

DOEpatents

The present invention relates to a method and apparatus for maintaining a steady-state current for magnetically confining the plasma in a toroidal magnetic confinement device using anomalous viscosity current drive. A second aspect of this invention relates to an apparatus and method for the start-up of a magnetically confined toroidal plasma.

Stix, T.H.; Ono, M.

1986-04-25

260

Anomalous GPDs in the photon  

E-print Network

We consider deeply virtual Compton scattering (DVCS) on a photon target, in the generalized Bjorken limit, at the Born order and in the leading logarithmic approximation. This leads us to the extraction of the photon anomalous generalized parton distributions (GPDs) \\cite{url, DVCSphoton}.

S. Friot; B. Pire; L. Szymanowski

2007-10-23

261

The UARS and EOS Microwave Limb Sounder (MLS) Experiments  

NASA Technical Reports Server (NTRS)

The Microwave Limb Sounder (MLlS) 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.

Waters, J. W.

1997-01-01

262

Microwave Oven Testing.  

National Technical Information Service (NTIS)

His program discusses the procedures of a microwave oven survey for testing of radiation leakage. The program also describes microwave production and cooking functions. Primary audience: state radiological health inspectors.

1994-01-01

263

Cosmic Microwave Background Tutorials  

NSDL National Science Digital Library

Probing whether space is curved or flat, cosmologists have been searching for clues in ripples in the universe's microwave background left from the big bang. These tutorials explain the cosmic microwave background for neophytes, as well as more advanced readers.

Hu, Wayne

2003-10-10

264

Vertical transport of surface fire emissions observed Siegfried Gonzi1  

E-print Network

combustion, at thermal infrared and microwave wavelengths from Aura Tropospheric Emission Spectrometer (TES) and Microwave Limb Sounder (MLS), respectively. TES and MLS together typically provide two to three pieces

Palmer, Paul

265

Determination of soluble toxic arsenic species in alga samples by microwave-assisted extraction and high performance liquid chromatography-hydride generation-inductively coupled plasma-atomic emission spectrometry.  

PubMed

A microwave-based procedure for arsenic species extraction in alga samples (Sargassum fulvellum, Chlorella vulgaris, Hizikia fusiformis and Laminaria digitata) is described. Extraction time and temperature were tested in order to evaluate the extraction efficiency of the process. Arsenic compounds were extracted in 8 ml of deionised water at 90 degrees C for 5 min. The process was repeated three times. Soluble arsenic compounds extracted accounted for about 78-98% of total arsenic. The results were compared with those obtained in a previous work, where the extraction process was carried out by ultrasonic focussed probe for 30 s. Speciation studies were carried out by high performance liquid chromatography-hydride generation-inductively coupled plasma-atomic emission spectrometry (HPLC-HG-ICP-AES). The chromatographic method allowed us to separate As(III), As(V), monomethylarsonic acid and dimethylarsinic acid in less than 13 min. The chromatographic analysis of the samples allowed us to identify and quantify As(V) in Hizikia sample and Sargasso material, while the four arsenic species studied were found in Chlorella sample. In the case of Laminaria sample, none of these species was identified by HPLC-HG-ICP-AES. However, in the chromatographic analysis of this alga by HPLC-ICP-AES, an unknown arsenic species was detected. PMID:16876177

García Salgado, S; Quijano Nieto, M A; Bonilla Simón, M M

2006-09-29

266

Microwave Photochemistry Organic Synthesis  

E-print Network

Microwave Photochemistry in Organic Synthesis V. C�rkva, M. H�jek Institute of Chemical Process pressure, ultraviolet radiation and recently applied microwave radiation. The paper is focused on combination of UV and microwave radiation technique, i.e. on the combination of short- and long

Cirkva, Vladimir

267

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

268

Decomposition of unpolarized emissivity  

Microsoft Academic Search

Many satellite remote sensors perform unpolarized measurements. A systematic procedure to decompose measured unpolarized emissivity is proposed using the definition of total reflectivity and the relationship between vertically and horizontally polarized reflectivity. Two polarizations are retrieved for various view angles with mixed emissivity simulated using the refractive index of water for ultraviolet, visible, infrared and microwave wavelengths. The results indicate

Sungwook Hong

2010-01-01

269

Quasars with Anomalous H? Profiles. I. Demographics  

NASA Astrophysics Data System (ADS)

The H? emission line in a typical Type I quasar is composed of a broad base and a narrow core, with the core velocity characteristic of narrow-line region emission, and line-fitting routines typically assume this picture. We test the effects of removing this constraint, and find a substantial group of Type I quasars in the Sloan Digital Sky Survey catalog with H? emission line cores broader than 1200 km s-1 , above the velocity believed possible for gas in the quasar narrow-line region. We identify this group of ``anomalous H? quasars'' (AHQs) as a distinct population because of a variety of spectral and photometric signatures common to these AHQs but atypical of other quasars. These features are similar to some aspects of narrow-line Seyfert 1s and correlations identified by Eigenvector 1, but also contain distinct features that make it difficult to classify AHQs. We demonstrate that AHQs comprise at least 11% and most likely approximately one quarter of the SDSS Type I quasar population at 0.2 < z < 0.8. For AHQs, the [O III]? 4959, 5007 profile is often better fit by de-linking it from the H? core, while a more standard linked fit produces a tight correlation between narrow- and broad-line velocities. We find that [O III] in AHQs sometimes has a standard narrow-line profile and other times matches the H? core, but is rarely in between the two, implying that the broadened core emission arises from a distinct physical region. Another feature of AHQs is a diminished [O II] line, which might indicate a connection between AHQs and the interstellar mediums of their host galaxies, through reduced photoionization or star formation. We find that it is difficult to produce AHQs using the current quasar standard model.

Steinhardt, Charles L.; Silverman, John D.

2013-08-01

270

Areas of Weakly Anomalous to Anomalous Surface Temperature in Chaffee County, Colorado, as Identified from ASTER Thermal Data  

SciTech Connect

Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Very Warm Modeled Temperature Chaffee Edition: First Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Chaffee County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature greater than 2? were considered ASTER modeled very warm surface exposures (thermal anomalies) Spatial Domain: Extent: Top: 4333432.368072 m Left: 366907.700763 m Right: 452457.816015 m Bottom: 4208271.566715 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

Khalid Hussein

2012-02-01

271

Areas of Weakly Anomalous to Anomalous Surface Temperature in Alamosa and Saguache Counties, Colorado, as Identified from ASTER Thermal Data  

SciTech Connect

Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Very Warm Modeled Temperature Alamosa Saguache Edition: First Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Alamosa and Saguache Counties identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature greater than 2? were considered ASTER modeled very warm surface exposures (thermal anomalies) Spatial Domain: Extent: Top: 4217727.601630 m Left: 394390.400264 m Right: 460179.841813 m Bottom: 4156258.036086 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

Khalid Hussein

2012-02-01

272

Areas of Weakly Anomalous to Anomalous Surface Temperature in Routt County, Colorado, as Identified from ASTER Thermal Data  

SciTech Connect

Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Warm Modeled Temperature Routt Edition: First Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Routt County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1? and 2? were considered ASTER modeled warm surface exposures (thermal anomalies) Spatial Domain: Extent: Top: 4501071.574000 m Left: 311351.975000 m Right: 359411.975000 m Bottom: 4447521.574000 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

Khalid Hussein

2012-02-01

273

Areas of Weakly Anomalous to Anomalous Surface Temperature in Archuleta County, Colorado, as Identified from ASTER Thermal Data  

SciTech Connect

Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Warm Modeled Temperature Archuleta Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Edition: First Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Archuleta County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1? and 2? were considered ASTER modeled warm surface exposures (thermal anomalies). Spatial Domain: Extent: Top: 4144825.235807 m Left: 285446.256851 m Right: 350577.338852 m Bottom: 4096962.250137 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

Khalid Hussein

2012-02-01

274

Areas of Weakly Anomalous to Anomalous Surface Temperature in Dolores County, Colorado, as Identified from ASTER Thermal Data  

SciTech Connect

Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Very Warm Modeled Temperature Dolores Edition: First Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Dolores County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature greater than 2? were considered ASTER modeled very warm surface exposures (thermal anomalies) Spatial Domain: Extent: Top: 4186234.213315 m Left: 212558.673056 m Right: 232922.811862 m Bottom: 4176781.467043 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

Khalid Hussein

2012-02-01

275

Areas of Weakly Anomalous to Anomalous Surface Temperature in Garfield County, Colorado, as Identified from ASTER Thermal Data  

SciTech Connect

Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Warm Modeled Temperature Garfield Edition: First Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Garfield County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1? and 2? were considered ASTER modeled warm surface exposures (thermal anomalies) Spatial Domain: Extent: Top: 4442180.552290 m Left: 268655.053363 m Right: 359915.053363 m Bottom: 4312490.552290 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

Khalid Hussein

2012-02-01

276

Medical applications of microwaves  

NASA Astrophysics Data System (ADS)

Medical applications of microwaves (i.e. a possibility to use microwave energy and/or microwave technique and technology for therapeutical purposes) are a quite new and a very rapidly developing field. Microwave thermotherapy is being used in medicine for the cancer treatment and treatment of some other diseases since early eighties. In this contribution we would like to offer general overview of present activities in the Czech Republic, i.e. clinical applications and results, technical aspects of thermo therapeutic equipment and last but not least, prospective diagnostics based on microwave principals ant technology and instrumentation.

Vrba, Jan; Lapes, M.

2004-04-01

277

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

278

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

279

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

280

On the X-Ray Light Curve, Pulsed-Radio Emission, and Spin Frequency Evolution of the Transient Anomalous X-Ray Pulsar XTE J1810-197 during Its X-Ray Outburst  

NASA Astrophysics Data System (ADS)

We show that (1) the long-term X-ray outburst light curve of the transient AXP XTE J1810-197 can be accounted for by a fallback disk that is evolving toward quiescence through a disk instability after having been heated by a soft gamma-ray burst, (2) the spin-frequency evolution of this source in the same period can also be explained by the disk torque acting on the magnetosphere of the neutron star, and (3) most significantly, recently observed pulsed-radio emission from this source coincides with the epoch of minimum X-ray luminosity. This is natural in terms of a fallback-disk model, as the accretion power becomes so low that it is not sufficient to suppress the beamed radio emission from XTE J1810-197.

Ertan, Ü.; Erkut, M. H.

2008-02-01

281

No evidence for anomalously low variance circles on the sky  

E-print Network

In a recent paper, Gurzadyan & Penrose claim to have found directions on the sky centred on which are circles of anomalously low variance in the cosmic microwave background (CMB). These features are presented as evidence for a particular picture of the very early Universe. We attempted to repeat the analysis of these authors, and we can indeed confirm that such variations do exist in the temperature variance for annuli around points in the data. However, we find that this variation is entirely expected in a sky which contains the usual CMB anisotropies. In other words, properly simulated Gaussian CMB data contain just the sorts of variations claimed. Gurzadyan & Penrose have not found evidence for pre-Big Bang phenomena, but have simply re-discovered that the CMB contains structure.

Moss, Adam; Zibin, James P

2010-01-01

282

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

283

Planck intermediate results. XXIII. Galactic plane emission components derived from Planck with ancillary data  

E-print Network

Planck data when combined with ancillary data provide a unique opportunity to separate the diffuse emission components of the inner Galaxy. The purpose of the paper is to elucidate the morphology of the various emission components in the strong star-formation region lying inside the solar radius and to clarify the relationship between the various components. The region of the Galactic plane covered is l=300-0-60deg where star-formation is highest and the emission is strong enough to make meaningful component separation. The latitude widths in this longitude range lie between 1deg and 2deg, which correspond to FWHM z-widths of 100-200pc at a typical distance of 6kpc. The four emission components studied here are synchrotron, free-free, anomalous microwave emission (AME), and thermal (vibrational) dust emission. These components are identified by constructing spectral energy distributions (SEDs) at positions along the Galactic plane using the wide frequency coverage of Planck (28.4-857GHz) in combination with l...

Ade, P A R; Alves, M I R; Arnaud, M; Ashdown, M; Atrio-Barandela, F; Aumont, J; Baccigalupi, C; Banday, A J; Barreiro, R B; Battaner, E; Benabed, K; Benoit-Lévy, A; Bernard, J -P; Bersanelli, M; Bielewicz, P; Bobin, J; Bonaldi, A; Bond, J R; Bouchet, F R; Boulanger, F; Burigana, C; Cardoso, J -F; Catalano, A; Chamballu, A; Chiang, H C; Christensen, P R; Clements, D L; Colombi, S; Colombo, L P L; Combet, C; Couchot, F; Crill, B P; Cuttaia, F; Danese, L; Davies, R D; Davis, R J; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Dickinson, C; Diego, J M; Donzelli, S; Doré, O; 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; Ghosh, T; Giard, M; Giardino, G; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gregorio, A; Gruppuso, A; Hansen, F K; Harrison, D L; Henrot-Versillé, S; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Hornstrup, A; Hovest, W; Huffenberger, K M; Jaffe, A H; Jaffe, T R; Jones, W C; Keihänen, E; Keskitalo, R; Kisner, T S; Kneissl, R; Knoche, J; Kunz, M; Kurki-Suonio, H; Lagache, G; Lähteenmäki, A; Lamarre, J -M; Lasenby, A; Lawrence, C R; Leonardi, R; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maino, D; Mandolesi, N; Martin, P G; Martínez-González, E; Masi, S; Massardi, M; Matarrese, S; Mazzotta, P; Meinhold, P R; Melchiorri, A; Mendes, L; Mennella, A; Migliaccio, M; Mitra, S; Miville-Deschênes, M -A; Moneti, A; Montier, L; Morgante, G; Mortlock, D; Munshi, D; Murphy, J A; Naselsky, P; Nati, F; Natoli, P; Nørgaard-Nielsen, H U; Noviello, F; Novikov, D; Novikov, I; Oxborrow, C A; Pagano, L; Pajot, F; Paladini, R; Paoletti, D; Pasian, F; Pearson, T J; Peel, M; Perdereau, O; Perrotta, F; Piacentini, F; Piat, M; Pierpaoli, E; Pietrobon, D; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Popa, L; Pratt, G W; Prunet, S; Puget, J -L; Rachen, J P; Reach, W T; Rebolo, R; Reich, W; Reinecke, M; Remazeilles, M; Renault, C; Ricciardi, S; Riller, T; Ristorcelli, I; Rocha, G; Rosset, C; Roudier, G; Rubiño-Martín, J A; Rusholme, B; Sandri, M; Savini, G; Scott, D; Spencer, L D; Stolyarov, V; Strong, A W; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Tavagnacco, D; Terenzi, L; Tibbs, C T; Toffolatti, L; Tomasi, M; Tristram, M; Tucci, M; Valenziano, L; Valiviita, J; Van Tent, B; Varis, J; Vielva, P; Villa, F; Wade, L A; Wandelt, B D; Watson, R; Yvon, D; Zacchei, A; Zonca, A

2014-01-01

284

Origin of anomalous slip in tungsten.  

PubMed

Low-temperature deformation of body-centered cubic metals shows a significant amount of plastic slip on planes with low shear stresses, a phenomenon called anomalous slip. Despite progress in atomistic modeling of the consequences of complex stress states on dislocation mobility, the phenomenon of anomalous slip remained elusive. Using in situ Laue microdiffraction and discrete dislocation dynamics in micrometer sized tungsten single crystals, we demonstrate the occurrence of significant anomalous slip. It occurs as a consequence of cross kinks, topological configurations generated by prior dislocation interactions. This clearly identifies anomalous slip as a multidislocation process and not a property of isolated dislocations. The cross-kink mechanism also explains the ambiguous reporting of anomalous slip traces in the past and directs us to ways of including anomalous slip in continuum crystal plasticity formulations. PMID:25062203

Marichal, C; Srivastava, K; Weygand, D; Van Petegem, S; Grolimund, D; Gumbsch, P; Van Swygenhoven, H

2014-07-11

285

Anomalous U(1) and Asymmetry  

E-print Network

In the past years many possible extensions of the Standard Model (SM) have been investigated. If one of this model is revealed at the LHC, we will need tools to distinguish it among the many others studied. One possibility to achieve this goal is to utilize the forward-backward asymmetry. In this paper we calculate the asymmetry for a model in which there is an extra U(1) anomalous symmetry. Furthermore, we show that the asymmetry can be used to impose constraints on the free parameters of the model.

Andrea Mammarella

2012-10-09

286

Quartic Anomalous Couplings in $??$ Colliders  

E-print Network

We study the constraints on the vertices $W^+W^- Z\\gamma$, $W^+W^-\\gamma\\gamma$, and $ZZ\\gamma\\gamma$ that can be obtained from triple-gauge-boson production at the next generation of linear $e^+e^-$ colliders operating in the $\\gamma\\gamma$ mode. We analyze the processes $\\gamma\\gamma \\to W^+W^-V$ ($V=Z$, or $\\gamma$) and show that these reactions increase the potential of $e^+e^-$ machines to search for anomalous four-gauge-boson interactions.

O. J. P. Eboli; M. B. Magro; P. G. Mercadante; S. F. Novaes

1995-03-24

287

Galilean satellites - Anomalous temperatures disputed  

NASA Technical Reports Server (NTRS)

Anomalous averaged infrared brightness temperatures of the Galilean satellites of Jupiter reported by Gross (1975) are rejected as falsely conceived and lacking physical reality. It is argued that the calculations of equilibrium temperatures should be corrected, whereupon predictions would be in satisfactory agreement with observations, in conformity with the radiometric method of determining the diameters of asteroids and satellites. The IR irradiance and the related disk-averaged brightness temperature for the spectral band are recommended as more relevant. Attention is drawn to some interesting discrepancies between calculated and observed temperatures of the Jovian satellites which merit further investigation.

Morrison, D.; Lebofsky, L. A.; Veeder, G. J.; Cutts, J. A.

1977-01-01

288

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

289

Anomalous Transport from Kubo Formulae  

NASA Astrophysics Data System (ADS)

Chiral anomalies have profound impact on the transport properties of relativistic fluids. In four dimensions there are different types of anomalies, pure gauge and mixed gauge-gravitational anomalies. They give rise to two new non-dissipative transport coefficients, the chiral magnetic conductivity and the chiral vortical conductivity. They can be calculated from the microscopic degrees of freedom with the help of Kubo formulae. We review the calculation of the anomalous transport coefficients via Kubo formulae with a particular emphasis on the contribution of the mixed gauge-gravitational anomaly.

Landsteiner, Karl; Megías, Eugenio; Peña-Benitez, Francisco

290

Anomalous Transport from Kubo Formulae  

E-print Network

Chiral anomalies have profound impact on the transport properties of relativistic fluids. In four dimensions there are different types of anomalies, pure gauge and mixed gauge-gravitational anomalies. They give rise to two new non-dissipative transport coefficients, the chiral magnetic conductivity and the chiral vortical conductivity. They can be calculated from the microscopic degrees of freedom with the help of Kubo formulae. We review the calculation of the anomalous transport coefficients via Kubo formulae with a particular emphasis on the contribution of the mixed gauge-gravitational anomaly.

Karl Landsteiner; Eugenio Megias; Francisco Pena-Benitez

2012-07-24

291

Ignition characteristics of methane/air premixed mixture by microwave-enhanced laser-induced breakdown plasma.  

PubMed

A microwave-enhanced plasma generation technique was combined with laser-induced ignition to improve ignition characteristics. A locally intensified microwave field was formed near the laser-induced breakdown plasma. As the plasma absorbed the microwaves, the plasma emission intensity increased. The plasma lifetime could be controlled by changing the microwave oscillation duration. Furthermore, the microwave-enhanced laser-induced breakdown plasma improved the minimum ignition energy of the methane/air pre-mixture with just a small amount of absorbed microwave energy. PMID:24514928

Nishiyama, Atsushi; Moon, Ahsa; Ikeda, Yuji; Hayashi, Jun; Akamatsu, Fumiteru

2013-11-01

292

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

293

Measurements of plasma potential in high-pressure microwave plasmas  

SciTech Connect

Plasma potential of a high-pressure ({approx}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.

Tarasova, A. V.; Podder, N. K. [Department of Math and Physics, Troy University, Troy, Alabama 36082 (United States); Clothiaux, E. J. [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)

2009-04-15

294

On the mechanism of electromagnetic microwave absorption in superfluid helium  

SciTech Connect

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{sub 0} Almost-Equal-To 110-180 GHz corresponding to the roton gap energy {Delta}{sub r}(T) in the temperature range 1.4-2.2 K. Using the so-called flexoelectric mechanism of polarization of helium atoms ({sup 4}He) 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{sub r-r} Almost-Equal-To 3.4 Multiplication-Sign 10{sup -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{sub 0}(T) = {Delta}r(T)/2{pi}h 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 {sup 4}He 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., E-mail: pashitsk@iop.kiev.ua; Pentegov, V. I. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

2012-08-15

295

On the problem of anomalous refraction  

NASA Astrophysics Data System (ADS)

Consideration is given to ways to improve daytime astronomical observations by accounting for anomalous refraction. Formulas are presented for taking into account anomalous vertical and lateral refraction due to different temperatures inside and outside the pavilion. The advantage of investigating the temperature outside the pavilion along the line of sight is emphasized.

Fedorov, P. N.; Shulga, A. V.

296

Forcing anomalous scaling on demographic fluctuations.  

PubMed

We discuss the conditions under which a population of anomalously diffusing individuals can be characterized by demographic fluctuations that are anomalously scaling themselves. Two examples are provided in the case of individuals migrating by Gaussian diffusion, and by a sequence of Lévy flights. PMID:23214831

Olla, Piero

2012-11-01

297

Dressed-quark anomalous magnetic moments.  

PubMed

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. PMID:21405508

Chang, Lei; Liu, Yu-Xin; Roberts, Craig D

2011-02-18

298

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

299

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

300

Satellite microwave observations of soil moisture variations. [by the microwave radiometer on the Nimbus 5 satellite  

NASA Technical Reports Server (NTRS)

The electrically scanning microwave radiometer (ESMR) on the Nimbus 5 satellite was used to observe microwave emissions from vegetated and soil surfaces over an Illinois-Indiana study area, the Mississippi Valley, and the Great Salt Lake Desert in Utah. Analysis of microwave brightness temperatures (T sub B) and antecedent rainfall over these areas provided a way to monitor variations of near-surface soil moisture. Because vegetation absorbs microwave emission from the soil at the 1.55 cm wavelength of ESMR, relative soil moisture measurements can only be obtained over bare or sparsely vegetated soil. In general T sub B increased during rainfree periods as evaporation of water and drying of the surface soil occurs, and drops in T sub B are experienced after significant rainfall events wet the soil. Microwave observations from space are limited to coarse resolutions (10-25 km), but it may be possible in regions with sparse vegetation cover to estimate soil moisture conditions on a watershed or agricultural district basis, particularly since daily observations can be obtained.

Schmugge, T. J.; Rango, A.; Neff, R.

1975-01-01

301

FIRST IMAGES OF IMPULSIVE MILLIMETER EMISSION AND SPECTRAL ANALYSIS OF THE  

E-print Network

at millimeter (86 GHz), microwave (1­18 GHz), and soft and hard X--ray wavelengths. Images of millimeter, soft spectrum was obtained by combining the millimeter with simultaneous microwave emission. Fitting--ray fluxes detectable by current instrumentation. The microwave emission is produced by electrons with a few

White, Stephen

302

Anomalous scattering of light on Triton  

NASA Technical Reports Server (NTRS)

Researchers report here the discovery of an isolated region of anomalously forward scattering materials on the surface of Triton. The researchers' best-fit Hapke parameters indicate that regolith particles in the anomalous scattering region are not only less backward scattering, but also slightly lower in single scattering albedo than average materials on Triton's surface. While it might be possible to account for such differences in terms of differences in particle size and transparency, it is also possible that the anomalous region is compositionally distinct from other terrains. It is noteworthy that, for the anomalous region, there exists a distinctively strong spatial correlation between the photometric ratios at different phase angles, and that, relative to other terrains, the anomalous region reddens at a different rate with increasing phase angle.

Helfenstein, Paul; Lee, Pascal; Mccarthy, Derek; Veverka, Joseph

1991-01-01

303

Microwave device investigations  

NASA Technical Reports Server (NTRS)

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) harmonic generation using Read diode varactors.

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

1972-01-01

304

Metamaterial based microwave devices  

Microsoft Academic Search

W e studied metamaterial based microwave devices and investigated the effect of electrical size of the con- stituting elements on the device performance. First, we identify and characterize the suitable subwavelength resonators that are used to create metamaterials. We continued by demonstrating electrically small, metamaterial loaded monopole and patch antennas, miniaturized microwave absorbers, and flat metamaterial lenses with in- creased

K. B. Alici; F. Bilotti; L. Vegni; E. Ozbay

2009-01-01

305

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

306

Microwave power transistors  

Microsoft Academic Search

The development of a microwave power amplifier transistor requires a highly advanced technology to achieve the basic parameters which theory predicts will be needed. In addition, very sophisticated microwave techniques must be used in the package design and characterization. Transitions between the active device and external circuitry often dominate performance. Development was started with a 7 mil2, seven-finger transistor with

H. F. Cooke; A. J. Anderson

1965-01-01

307

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

308

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

309

Variable frequency microwave heating apparatus  

DOEpatents

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, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN); Johnson, Arvid C. (Lake in the Hills, IL); Thigpen, Larry T. (Angier, NC)

1999-01-01

310

Validation of UARS Microwave Limb Sounder temperature and pressure measurements  

Microsoft Academic Search

The accuracy and precision of the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS) atmospheric temperature and tangent-point pressure measurements are described. Temperatures and tangent-point pressure (atmospheric pressure at the tangent height of the field of view boresight) are retrieved from a 15-channel 63-GHz radiometer measuring O2 microwave emissions from the stratosphere and mesosphere. The Version 3 data (first

E. F. Fishbein; R. E. Cofield; L. Froidevaux; R. F. Jarnot; T. Lungu; W. G. Read; Z. Shippony; J. W. Waters; I. S. McDermid; T. J. McGee; U. Singh; M. Gross; A. Hauchecorne; P. Keckhut; M. E. Gelman; R. M. Nagatani

1996-01-01

311

Microwave hydrology: A trilogy  

NASA Technical Reports Server (NTRS)

Microwave hydrology, as the term in construed in this trilogy, deals with the investigation of important hydrological features on the Earth's surface as they are remotely, and passively, sensed by orbiting microwave receivers. Microwave wavelengths penetrate clouds, foliage, ground cover, and soil, in varying degrees, and reveal the occurrence of standing liquid water on and beneath the surface. The manifestation of liquid water appearing on or near the surface is reported by a microwave receiver as a signal with a low flux level, or, equivalently, a cold temperature. Actually, the surface of the liquid water reflects the low flux level from the cosmic background into the input terminals of the receiver. This trilogy describes and shows by microwave flux images: the hydrological features that sustain Lake Baykal as an extraordinary freshwater resource; manifestations of subsurface water in Iran; and the major water features of the Congo Basin, a rain forest.

Stacey, J. M.; Johnston, E. J.; Girard, M. A.; Regusters, H. A.

1985-01-01

312

Comment on anomalous Anisotropic Light Scattering in Ge-Doped Silica Glass  

E-print Network

This is a comment on a paper by Kazansky et al. appeared in Phys. Rev. Lett., 82, 2199 (1999). We demonstrate that the bremsstrahlung of photoelectrons, which oscillate in the light field of an ultrashort laser pulse, accounts for the anomalous anisotropic light scattering, the "propeller effect", described in the paper of Kazansky et al. This mechanism of light emission could explain some results of white-light continuum generation and dielectric breakdown emission.

Juodkazis, S; Misawa, H; Juodkazis, Saulius; Matsuo, Shigeki; Misawa, Hiroaki

2002-01-01

313

Anomalous Sediment Mixing by Bioturbation  

NASA Astrophysics Data System (ADS)

Bioturbation, the reworking of sediments by animals and plants, is the dominant mode of sediment mixing in low-energy environments, and plays an important role in sedimentary biogeochemical processes. Mixing resulting from bioturbation has historically been modeled as a diffusive process. However, diffusion models often do not provide a sufficient description of sediment mixing due to bioturbation. Stochastic models, such as the continuous time random walk (CTRW) model, provide more general descriptions of mixing behavior that are applicable even when regular diffusion assumptions are not met. Here we present results from an experimental investigation of anomalous sediment mixing by bioturbation in freshwater sediments. Clean and heavy-metal-contaminated sediments were collected from Lake DePue, a backwater lake of the Illinois River. The burrowing worm species Lumbriculus variegatus was introduced to homogenized Lake DePue sediments in aerated aquaria. We then introduced inert fine fluorescent particles to the sediment-water interface. Using time-lapse photography, we observed the mixing of the fluorescent particles into the sediment bed over a two-week period. We developed image analysis software to characterize the concentration distribution of the fluorescent particles as a function of sediment depth, and applied this to the time-series of images to evaluate sediment mixing. We fit a one-dimensional CTRW model to the depth profiles to evaluate the underlying statistical properties of the mixing behavior. This analysis suggests that the sediment mixing caused by L. variegatus burrowing is subdiffusive in time and superdiffusive in space. We also found that heavy metal contamination significantly reduces L. variegatus burrowing, causing increasingly anomalous sediment mixing. This result implies that there can be important feedbacks between sediment chemistry, organism behavior, and sediment mixing that are not considered in current environmental models.

Roche, K. R.; Aubeneau, A. F.; Xie, M.; Packman, A. I.

2013-12-01

314

Planck intermediate results. XXXI. Microwave survey of Galactic supernova remnants  

E-print Network

The all-sky Planck survey in 9 frequency bands was used to search for emission from all 274 known Galactic supernova remnants. Of these, 17 were detected in at least two Planck frequencies. The radio-through-microwave spectral energy distributions were compiled to determine the emission mechanism for microwave emission. In only one case, IC 443, is the high-frequency emission clearly from dust associated with the supernova remnant. In all cases, the low-frequency emission is from synchrotron radiation. A single power law, as predicted for a population of relativistic particles with energy distribution that extends continuously to high energies, is evident for many sources, including the Crab and PKS 1209-51/52. A decrease in flux density relative to the extrapolation of radio emission is evident in several sources. Their spectral energy distributions can be approximated as broken power laws, $S_\

Arnaud, M

2014-01-01

315

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

316

Microwave Loss Reduction in Cryogenically Cooled Conductors  

NASA Astrophysics Data System (ADS)

Measurements of microwave attenuation at room temperature and 4.2 K have been performed on some conductors commonly used in receiver input circuits. The reduction in loss on cooling is substantial, particularly for copper and plated gold, both of which showed a factor of 3 loss reduction. Copper passivated with benzotriazole shows the same loss as without passivation. The residual resistivity ratio between room temperature and 4.2 K, deduced from the measurements using the classical skin effect formula, was smaller than the measured DC value to a degree consistent with conduction in the extreme anomalous skin effect regime at cryogenic temperatures. The measurements were made in the 5-10 GHz range. The materials tested were: aluminum alloys 1100-T6 and 6061-O, C101 copper, benzotriazole treated C101 copper, and brass plated with electroformed copper, Pur-A-Gold 125-Au soft gold, and BDT200 bright gold.

Finger, R.; Kerr, A. R.

2008-10-01

317

Microwave Schottky Ralph J. Pasquinelli  

E-print Network

Microwave Schottky Pickups at Fermilab Ralph J. Pasquinelli May 9, 2003 #12;5/9/03 LARP Collaboration R. J. Pasquinelli Microwave Schottky Pickups Microwave Schottky Pickups at Fermilab Pickup Design #12;5/9/03 LARP Collaboration R. J. Pasquinelli Microwave Schottky Pickups Slotted Waveguide Pickup 1

Large Hadron Collider Program

318

Microwave Photochemistry Petr KLN a  

E-print Network

Chapter 14 Microwave Photochemistry Petr KLÁN a and Vladimír CÍRKVA b a Department of Organic 14.2.3 Spectral characteristics of EDLs 14.3 Microwave photochemical reactor 14.4. Microwave photochemistry 14.4.1 Interactions of ultraviolet and microwave radiation with matter 14.4.2 Photochemical

Cirkva, Vladimir

319

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

2010-10-22

320

Microwave Lens for Polar Molecules  

E-print Network

We here report on the implementation of a microwave lens for neutral polar molecules suitable to focus molecules both in low-field-seeking and in high-field-seeking states. By using the TE_11m modes of a 12 cm long cylindrically symmetric microwave resonator, Stark-decelerated ammonia molecules are transversally confined. We investigate the focusing properties of this microwave lens as a function of the molecules' velocity, the detuning of the microwave frequency from the molecular resonance frequency, and the microwave power. Such a microwave lens can be seen as a first important step towards further microwave devices, such as decelerators and traps.

Odashima, Hitoshi; Enomoto, Katsunari; Schnell, Melanie; Meijer, Gerard

2010-01-01

321

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

322

Parallel electric fields in extragalactic jets - double layers and anomalous resistivity in symbiotic relationships  

SciTech Connect

After examining the properties of Coulomb-collision resistivity, anomalous (collective) resistivity, and double layers, a hybrid anomalous-resistivity/double-layer model is introduced. In this model, beam-driven waves on both sides of a double layer provide electrostatic plasma-wave turbulence that greatly reduces the mobility of charged particles. These regions then act to hold open a density cavity within which the double layer resides. In the double layer, electrical energy is dissipated with 100 percent efficiency into high-energy particles, creating conditions optimal for the collective emission of polarized radio waves. 102 references.

Borovsky, J.E.

1986-07-01

323

Parallel electric fields in extragalactic jets - Double layers and anomalous resistivity in symbiotic relationships  

NASA Technical Reports Server (NTRS)

After examining the properties of Coulomb-collision resistivity, anomalous (collective) resistivity, and double layers, a hybrid anomalous-resistivity/double-layer model is introduced. In this model, beam-driven waves on both sides of a double layer provide electrostatic plasma-wave turbulence that greatly reduces the mobility of charged particles. These regions then act to hold open a density cavity within which the double layer resides. In the double layer, electrical energy is dissipated with 100 percent efficiency into high-energy particles, creating conditions optimal for the collective emission of polarized radio waves.

Borovsky, J. E.

1986-01-01

324

Anomalous Hall Effect Arising from Noncollinear Antiferromagnetism  

NASA Astrophysics Data System (ADS)

As established in the very early work of Edwin Hall, ferromagnetic conductors have an anomalous Hall conductivity contribution that cannot be attributed to Lorentz forces and therefore survives in the absence of a magnetic field. These anomalous Hall conductivities are normally assumed to be proportional to magnetization. We use symmetry arguments and first-principles electronic structure calculations to counter this assumption and to predict that Mn3Ir, a high-temperature antiferromagnet that is commonly employed in spin-valve devices, has a large anomalous Hall conductivity.

Chen, Hua; Niu, Qian; MacDonald, A. H.

2014-01-01

325

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

326

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, C.E.

1984-11-29

327

Microwave ice prevention  

NASA Technical Reports Server (NTRS)

The concept of using microwave energy to provide aircraft ice protection, specifically an anti-icing system, and the feasibility of such a system are discussed. In a microwave anti-icing system impinging supercooled water droplets are heated to above freezing by the resonant absorption of microwave energy located upstream of the aircraft. This process is inherently more efficient than existing anti-icing devices due to the saving of the latent heat of fusion (a substantial 334 joules/gm (80 cal/gm)) and the fact that only the droplets are heated, thereby reducing convective losses to the air.

Hansman, R. J., Jr.; Hollister, W.

1982-01-01

328

Microwave Comb Generator  

NASA Technical Reports Server (NTRS)

Stable reference tones aid testing and calibration of microwave receivers. Signal generator puts out stable tones in frequency range of 2 to 10 GHz at all multiples of reference input frequency, at any frequency up to 1 MHz. Called "comb generator" because spectral plot resembles comb. DC reverse-bias current switched on and off at 1 MHz to generate sharp pulses in step-recovery diode. Microwave components mounted on back of special connector containing built-in attenuator. Used in testing microwave and spread-spectrum wide-band receivers.

Sigman, E. H.

1989-01-01

329

Electromagnetic and acoustic emission associated with rock fracture  

Microsoft Academic Search

To understand the physical mechanism of the anomalous electromagnetic emissions observed before earthquakes, we carried out some laboratory experiments on electromagnetic and acoustic emission from a rock. Granitic samples were loaded at a constant strain rate and electromagnetic and acoustic emission were simultaneously recorded during deformation of the sample. Ten to 20% of the acoustic emissions detected during the experiment

I. Yamada; K. Masuda; H. Mizutani

1989-01-01

330

Microwave sensing from orbit  

NASA Technical Reports Server (NTRS)

Microwave sensors, used in conjunction with the traditional sensors of visible and infrared light to extend present capabilities of global weather forecasts and local storm watches, are discussed. The great advantage of these sensors is that they can penetrate or 'see' through cloud formations to monitor temperature, humidity and wind fields below the clouds. Other uses are that they can penetrate the earth deeper than optical and IR systems; they can control their own angle of incidence; they can detect oil spills; and they can enhance the studies of the upper atmosphere through measurement of temperature, water vapor and other gaseous species. Two types of microwave sensors, active and passive, are examined. Special attention is given to the study of the microwave radiometer and the corresponding temperature resolution as detected by the antenna. It is determined that not only will the microwave remote sensors save lives by allowing close monitoring of developing storms, but also save approximately $172 million/year.

Kritikos, H. N.; Shiue, J.

1979-01-01

331

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

332

Microwave approaches in hydrology  

NASA Technical Reports Server (NTRS)

The microwave approaches for remote sensing of soil moisture centent, snowpack properties, surface water area, and the detection of precipitation over land are discussed. Both active (radar) and passive (radiometry) approaches are considered, and the advantages of microwave sensing are pointed out, including all-weather capability, especially at the longer wavelengths, and greater penetration depth with optical or infrared sensors. Results obtained from ground-based, aircraft, and spacecraft platforms show that microwave systems can monitor the moisture content in the surface soil layer (5 cm thick), and that passive microwave systems can discriminate between light and heavy snowcover, detect the presence of liquid water in the snow, and qualitatively estimate snow water equivalent.

Schmugge, T. J.

1980-01-01

333

Anomalous behaviour of molybdenum in steel welds  

E-print Network

The addition of molybdenum to steel welds in quite small concentrations leads to a variety of anomalous microstructural and mechanical property effects. In some cases, the effects manifest even when there are no obvious changes in microstructure...

Choudhary, Habib Ullah

334

Anomalous Diffraction in Crystallographic Phase Evaluation  

PubMed Central

X-ray diffraction patterns from crystals of biological macromolecules contain sufficient information to define atomic structures, but atomic positions are inextricable without having electron-density images. Diffraction measurements provide amplitudes, but the computation of electron density also requires phases for the diffracted waves. The resonance phenomenon known as anomalous scattering offers a powerful solution to this phase problem. Exploiting scattering resonances from diverse elements, the methods of multiwavelength anomalous diffraction (MAD) and single-wavelength anomalous diffraction (SAD) now predominate for de novo determinations of atomic-level biological structures. This review describes the physical underpinnings of anomalous diffraction methods, the evolution of these methods to their current maturity, the elements, procedures and instrumentation used for effective implementation, and the realm of applications. PMID:24726017

Hendrickson, Wayne A.

2014-01-01

335

Anomalous transport through porous and fractured media  

E-print Network

Anomalous transport, understood as the nonlinear scaling with time of the mean square displacement of transported particles, is observed in many physical processes, including contaminant transport through porous and fractured ...

Kang, Peter Kyungchul

2014-01-01

336

Anomalous Dynamics of Forced Translocation  

E-print Network

We consider the passage of long polymers of length N through a hole in a membrane. If the process is slow, it is in principle possible to focus on the dynamics of the number of monomers s on one side of the membrane, assuming that the two segments are in equilibrium. The dynamics of s(t) in such a limit would be diffusive, with a mean translocation time scaling as N^2 in the absence of a force, and proportional to N when a force is applied. We demonstrate that the assumption of equilibrium must break down for sufficiently long polymers (more easily when forced), and provide lower bounds for the translocation time by comparison to unimpeded motion of the polymer. These lower bounds exceed the time scales calculated on the basis of equilibrium, and point to anomalous (sub-diffusive) character of translocation dynamics. This is explicitly verified by numerical simulations of the unforced translocation of a self-avoiding polymer. Forced translocation times are shown to strongly depend on the method by which the force is applied. In particular, pulling the polymer by the end leads to much longer times than when a chemical potential difference is applied across the membrane. The bounds in these cases grow as N^2 and N^{1+\

Yacov Kantor; Mehran Kardar

2003-10-22

337

Microwave pyrolysis of biomass  

Microsoft Academic Search

Because of the inherent moisture and large particle size of wood used in the Forest Products Industry, there has been regional\\u000a interest in exploring the feasibility of processing wood, cellulose, and other such related materials using microwave dielectric-loss\\u000a heating. A research project was undertaken in the late 1970’s to determine the important variables altering the rate of microwave-induced\\u000a reactions of

B. Krieger-Brockett

1994-01-01

338

Microwave dielectric resonators  

NASA Astrophysics Data System (ADS)

A historical review and a status report on the state of the art of microwave dielectric resonators are presented. Early experimental works predating practical applications are noted, including work on rutile in the 1960s and the breakthrough development of stable low-less barium tetratitanate ceramics. Topics include: theory of operation, coupling to microwave structures, ceramic materials, applications, various filters, diode oscillators, and FET or bipolar transistor oscillators.

Fiedziuszko, S. J.

1986-09-01

339

Anomalous magnetic diffusion in coronal current layers  

Microsoft Academic Search

The current-driven kinetic Alfvén instability is proposed as an anomalous transport mechanism for regions of concentrated, field-aligned currents in the solar corona. Anomalous magnetic diffusivity (?e f f = 109cm2s-1), produced by kinetic Alfvén turbulence in the vicinity of the saturation level, provides fast magnetic energy release with a local inflow Alfvén Mach numberMin = 0.1.

Yurii M. Voitenko

1995-01-01

340

Fronts in anomalous diffusion-reaction systems.  

PubMed

A review of recent developments in the field of front dynamics in anomalous diffusion-reaction systems is presented. Both fronts between stable phases and those propagating into an unstable phase are considered. A number of models of anomalous diffusion with reaction are discussed, including models with Lévy flights, truncated Lévy flights, subdiffusion-limited reactions and models with intertwined subdiffusion and reaction operators. PMID:23185056

Volpert, V A; Nec, Y; Nepomnyashchy, A A

2013-01-13

341

Microwave Quantum Illumination  

E-print Network

Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally-occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or 'quantum radar', is shown to be superior to that of any classical microwave radar of equal transmit...

Barzanjeh, Shabir; Weedbrook, Christian; Vitali, David; Shapiro, Jeffrey H; Pirandola, Stefano

2014-01-01

342

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

343

Joint characterization of vegetation by satellite observations from visible to microwave wavelengths: A sensitivity analysis  

Microsoft Academic Search

This study presents an evaluation and comparison of visible, near-infrared, passive and active microwave observations for vegetation characterization, on a global basis, for a year, with spatial resolution compatible with climatological studies. Visible and near-infrared observations along with the Normalized Difference Vegetation Index come from the Advanced Very High Resolution Radiometer. An atlas of monthly mean microwave land surface emissivities

Catherine Prigent; Filipe Aires; William Rossow; Elaine Matthews

2001-01-01

344

New microwave spectrometer/imager has possible applications for pollution monitoring  

NASA Technical Reports Server (NTRS)

Microwave imager forms thermal-emissivity image of solid portion of planet Venus and provides data on the planet's atmosphere, surface, terminator, and temperature changes. These thermally produced multifrequency microwaves for image production of temperature profiles can be applied to water pollution monitoring, agriculture, and forestry survey.

Tooley, R. D.

1970-01-01

345

Microwave radiation absorption: Behavioral effects  

SciTech Connect

The literature contains much evidence that absorption of microwave energy will lead to behavioral changes in man and laboratory animals. The changes include simple perturbations or outright stoppage of ongoing behavior. On one extreme, intense microwave absorption can result in seizures followed by death. On the other extreme, man and animals can hear microwave pulses at very low rates of absorption. Under certain conditions of exposure, animals will avoid microwaves, while under other conditions, they will actively work to obtain warmth produced by microwaves. Some research has shown behavioral effects during chronic exposure to low-level microwaves. The specific absorption rates that produce behavioral effects seem to depend on microwave frequency, but controversy exists over thresholds and mechanism of action. In all cases, however, the behavioral disruptions cease when chronic microwave exposure is terminated. Thermal changes in man and animals during microwave exposure appear to account for all reported behavioral effects. 66 refs.

D'Andrea, J.A. (Naval Aerospace Medical Research Laboratory, Naval Air Station, Pensacola, FL (USA))

1991-07-01

346

Application of Monte Carlo algorithms to the Bayesian analysis of the Cosmic Microwave Background  

NASA Technical Reports Server (NTRS)

Power spectrum estimation and evaluation of associated errors in the presence of incomplete sky coverage; nonhomogeneous, correlated instrumental noise; and foreground emission are problems of central importance for the extraction of cosmological information from the cosmic microwave background (CMB).

Jewell, J.; Levin, S.; Anderson, C. H.

2004-01-01

347

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

348

A microwave transmission spectrometer  

NASA Astrophysics Data System (ADS)

The design and performance of a microwave transmission spectrometer operating in the 12.4-18 GHz frequency range is described. This spectrometer measures the microwave power passing through a magnetic, metallic sample as a function of temperature and applied magnetic field. Significant features of the apparatus are the use of a solid state microwave amplifier as the homodyne receiver's front end and the inclusion of a calibration signal which is injected into the receiver simultaneously with the signal to be measured. The excellent noise figure (<2 dB) and gain (?34 dB) of the amplifier yield a receiver sensitivity of ?10-20 W in a 1 Hz bandwidth. The present microwave source is a dielectric resonant oscillator which generates 100 mW at 16.95 GHz, although the system can also operate with a klystron or microwave sweep oscillator locked to any frequency between 12.4 and 18 GHz. The first use of the system was to measure the transmission through the amorphous ferromagnet Metglas(R) 2605SC (Allied Chemical Corporation). A peak in the transmission was observed at ferromagnetic resonance. This transmission peak was contaminated by a signal going around, not through, the sample which we tentatively identify with surface acoustic waves.

Waldfried, Carlo; Wadewitz, Scott; Dewar, G.

1994-05-01

349

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

350

Satellite Remote Sensing: Passive-Microwave Measurements of Sea Ice  

NASA Technical Reports Server (NTRS)

Satellite passive-microwave measurements of sea ice have provided global or near-global sea ice data for most of the period since the launch of the Nimbus 5 satellite in December 1972, and have done so with horizontal resolutions on the order of 25-50 km and a frequency of every few days. These data have been used to calculate sea ice concentrations (percent areal coverages), sea ice extents, the length of the sea ice season, sea ice temperatures, and sea ice velocities, and to determine the timing of the seasonal onset of melt as well as aspects of the ice-type composition of the sea ice cover. In each case, the calculations are based on the microwave emission characteristics of sea ice and the important contrasts between the microwave emissions of sea ice and those of the surrounding liquid-water medium.

Parkinson, Claire L.; Zukor, Dorothy J. (Technical Monitor)

2001-01-01

351

Uniform batch processing using microwaves  

NASA Technical Reports Server (NTRS)

A microwave oven and microwave heating method generates microwaves within a cavity in a predetermined mode such that there is a known region of uniform microwave field. Samples placed in the region will then be heated in a relatively identical manner. Where perturbations induced by the samples are significant, samples are arranged in a symmetrical distribution so that the cumulative perturbation at each sample location is the same.

Barmatz, Martin B. (Inventor); Jackson, Henry W. (Inventor)

2000-01-01

352

COBE Observations of the Microwave Counterparts of Gamma Ray Bursts  

E-print Network

We have used the data from the COBE satellite to search for delayed microwave emission (31 - 90 GHz) from Gamma Ray Bursts (GRBs). The large $7^\\circ$ beam of COBE is well matched to the large positional uncertainties in the GRB locations, although it also means that fluxes from (point source) GRB objects will be diluted. In view of this we are doing a statistical search of the GRBs which occurred during the currently released COBE DMR data (years 1990 and 1991), which overlap $\\sim 200$ GRBs recorded by GRO. Here we concentrate on just the top 10 GRBs (in peak counts/second). We obtain the limits on the emission by comparing the COBE fluxes before and after the GRB at the GRB location. Since it is thought that the microwave emission should lag the GRB event, we have searched the GRB position for emission in the few months following the GRB occurrence.

R. K. Schaefer; S. Ali; M. Limon; L. Piccirillo

1995-06-08

353

MICROWAVE PHOTOCHEMISTRY OF SUBSTITUTED PHENOLS  

E-print Network

MICROWAVE PHOTOCHEMISTRY OF SUBSTITUTED PHENOLS V. C�rkva, J. Kurf�rstov�, M. H�jek Institute into the microwave field (MW) has been known for long time [1-3]. The low powered and low-pressure electrodeless of microwave photochemistry of substituted phenols in an original photoche- mical reactor consisting of EDL

Cirkva, Vladimir

354

6, 54275456, 2006 Passive microwave  

E-print Network

ACPD 6, 5427­5456, 2006 Passive microwave 3-D polarization effects from rainy clouds A. Battaglia in polarization signatures as observed from precipitating clouds by low frequency ground-based microwave, 5427­5456, 2006 Passive microwave 3-D polarization effects from rainy clouds A. Battaglia et al. Title

Boyer, Edmond

355

Botswana water and surface energy balance research program. Part 2: Large scale moisture and passive microwaves  

NASA Technical Reports Server (NTRS)

The Botswana water and surface energy balance research program was developed to study and evaluate the integrated use of multispectral satellite remote sensing for monitoring the hydrological status of the Earth's surface. The research program consisted of two major, mutually related components: a surface energy balance modeling component, built around an extensive field campaign; and a passive microwave research component which consisted of a retrospective study of large scale moisture conditions and Nimbus scanning multichannel microwave radiometer microwave signatures. The integrated approach of both components are explained in general and activities performed within the passive microwave research component are summarized. The microwave theory is discussed taking into account: soil dielectric constant, emissivity, soil roughness effects, vegetation effects, optical depth, single scattering albedo, and wavelength effects. The study site is described. The soil moisture data and its processing are considered. The relation between observed large scale soil moisture and normalized brightness temperatures is discussed. Vegetation characteristics and inverse modeling of soil emissivity is considered.

Vandegriend, A. A.; Owe, M.; Chang, A. T. C.

1992-01-01

356

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

357

Leakage of microwave ovens  

NASA Astrophysics Data System (ADS)

Physics is essential for students who want to succeed in science and engineering. Excitement and interest in the content matter contribute to enhancing this success. We have developed a laboratory experiment that takes advantage of microwave ovens to demonstrate important physical concepts and increase interest in physics. This experiment investigates leaked electromagnetic radiation from microwave ovens. We compare the data that are obtained to national standards in order to relate the fields of physics, health and engineering. The experiment is designed to provide for added enquiry and stimulation of thought-provoking questions.

Abdul-Razzaq, W.; Bushey, R.; Winn, G.

2011-07-01

358

Compact microwave ion source  

SciTech Connect

A small microwave ion source has been fabricated from a quartz tube with one end enclosed by a two grid accelerator. The source is also enclosed by a cavity operated at a frequency of 2.45 GHz. Microwave power as high as 500 W can be coupled to the source plasma. The source has been operated with and without multicusp fields for different gases. In the case of hydrogen, ion current density of 200 mA/cm/sup -2/ with atomic ion species concentration as high as 80% has been extracted from the source.

Leung, K.N.; Walther, S.; Owren, H.W.

1985-05-01

359

EDITORIAL: Microwave Moisture Measurements  

NASA Astrophysics Data System (ADS)

Microwave moisture measurements refer to a methodology by which the water content of materials is non-invasively determined using electromagnetic fields of radio and microwave frequencies. Being the omnipresent liquid on our planet, water occurs as a component in most materials and often exercises a significant influence on their properties. Precise measurements of the water content are thus extremely useful in pure sciences, particularly in biochemistry and biophysics. They are likewise important in many agricultural, technical and industrial fields. Applications are broad and diverse, and include the quality assessment of foodstuffs, the determination of water content in paper, cardboard and textile production, the monitoring of moisture in sands, gravels, soils and constructions, as well as the measurement of water admixtures to coal and crude oil in reservoirs and in pipelines. Microwave moisture measurements and evaluations require insights in various disciplines, such as materials science, dielectrics, the physical chemistry of water, electrodynamics and microwave techniques. The cooperation of experts from the different fields of science is thus necessary for the efficient development of this complex discipline. In order to advance cooperation the Workshop on Electromagnetic Wave Interaction with Water and Moist Substances was held in 1993 in Atlanta. It initiated a series of international conferences, of which the last one was held in 2005 in Weimar. The meeting brought together 130 scientists and engineers from all over the world. This special issue presents a collection of some selected papers that were given at the event. The papers cover most topics of the conference, featuring dielectric properties of aqueous materials, electromagnetic wave interactions, measurement methods and sensors, and various applications. The special issue is dedicated to Dr Andrzej W Kraszewski, who died in July 2006 after a distinguished career of 48 years in the research of microwave applications. Dr Kraszewski was a pioneer in moisture content sensing and the founder of microwave aquametry. He organized the first conferences on electromagnetic wave interactions with water and moist substances and helped to maintain the progress of microwave aquametry research internationally. Andrzej Kraszewski is missed by the microwave moisture measurement community who appreciated both his unusual technical ability and his pleasant and endearing character. Andrzej W Kraszewski, 1933-2006 We hope you will enjoy reading these papers and will extend your scientific curiosity to this field. Finally, we would like to thank all the authors, referees and the staff of Measurement Science and Technology for their contributions and support which have made the publication of this special issue possible.

Kaatze, Udo; Kupfer, Klaus; Hübner, Christof

2007-04-01

360

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

361

Microwave Preflare Enhancement and Depletion in Long Duration Events  

NASA Astrophysics Data System (ADS)

Combination of weak microwave enhancement and depletion has been found in the pre-flare phases of three long-duration solar flares observed with the Nobeyama radioheliograph (NRH) at 17 GHz. This starts about two hours prior to subsequent main flare. Emission measure and temperature indicate that the enhancement and the depletion are caused by a, relatively cool plasma motion

Fujiki, K.; Nakajima, H.

362

The Microwave Spectrum of Oxygen in the Earth's Atmosphere  

Microsoft Academic Search

Space probe techniques open the possibility of radio and microwave spectroscopic investigations of planetary atmospheres through the study of resonant transitions in gaseous constituents. Computations were undertaken to determine the opacity and the thermal emis- sion produced by the millimeter-wavelength complex of oxygen lines in the earth's atmosphere. The calculations predict line profiles of individual oxygen transitions in emission or

M. L. Meeks; A. E. Lilley

1963-01-01

363

Solar-burst precursors and energy buildup at microwave wavelengths  

Microsoft Academic Search

High-resolution microwave observations (VLA) of heating and magnetic triggering in coronal loops are summarized. Magnetic changes that precede solar eruptions on time scales of tens of minutes involve primarily emerging coronal loops and the interaction of two or more loops. Thermal cyclotron lines were detected in coronal loops, suggesting the presence of hot current sheets that enhance emission from relatively

K. R. Lang; R. F. Willson

1986-01-01

364

A blended land emissivity product from the Inter-Comparison of different Land Surface Emissivity Estimates  

NASA Astrophysics Data System (ADS)

Passive microwave observations are routinely used to estimate rain rate, cloud liquid water, and total precipitable water. In order to have accurate estimations from microwave, the contribution of the surface should be accounted for. Over land, due to the complex interaction between the microwave signal and the soil surface, retrieval of land surface emissivity and other surface and subsurface parameters is not straightforward. Several microwave emissivity products from various microwave sensors have been proposed. However, lack of ground truth measurements makes the validation of these products difficult. This study aims to inter-compare several available emissivity products over land and ultimately proposes a unique blended product that overcomes the flaws of each individual product. The selected products are based on observations from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E), the Special Sensor Microwave Imager (SSM/I), the Advanced Microwave Sounding unit (AMSU), and the Special Sensor Microwave Imager/Sounder (SSMIS). In retrieval of emissivities from these sensors different methods and ancillary data have been used. Some inherent discrepancies between the selected products can be introduced by as the difference in geometry in terms of incident angle, spectral response, and the foot print size which can affect the estimations. Moreover, ancillary data especially skin temperature and cloud mask cover can cause significant discrepancies between various estimations. The time series and correlation between emissivity maps are explored to assess the consistency of emissivity variations with geophysical variable such as snow, precipitation and drought. Preliminary results reveal that inconsistency between products varies based on land cover type due to penetration depth effect and ancillary data. Six years of estimations are employed in this research study, and a global blended emissivity estimations based on all product with minimal discrepancies is proposed.

Norouzi, H.; Temimi, M.; Khanbilvardi, R.

2012-12-01

365

Anomalous transport equations in toroidal plasmas  

SciTech Connect

Reduced transport equations for a toroidal plasma with fluctuations are derived. These equations include the effects of both anomalous and standard neoclassical transport, and allow clarification of the structure of convective fluxes caused by electrostatic and magnetic fluctuations. Special attention is paid to the combined effects of fluctuations and toroidicity on the transport. The formulation retains the effects of a magnetic field inhomogeneity on the anomalous transport. It is shown that phase space diffusion caused by the gradient in the equilibrium magnetic field appears as a pinch flux in the real space.

Smolyakov, A.I.; Hirose, A. [Univ. of Saskatchewan, Saskatoon (Canada); Callen, J.D. [Univ. of Wisconsin, Madison, WI (United States)

1994-03-01

366

Communication: A scaling approach to anomalous diffusion.  

PubMed

The paper presents a rigorous derivation of the velocity autocorrelation function for an anomalously diffusing slow solute particle in a bath of fast solvent molecules. The result is obtained within the framework of the generalized Langevin equation and uses only scaling arguments and identities which are based on asymptotic analysis. It agrees with the velocity autocorrelation function of an anomalously diffusing Rayleigh particle whose dynamics is described by a fractional Ornstein-Uhlenbeck process in velocity space. A simple semi-analytical example illustrates under which conditions the latter model is appropriate. PMID:25084871

Kneller, Gerald R

2014-07-28

367

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

368

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

369

ASCA observations of SS Cygni during an anomalous outburst  

NASA Technical Reports Server (NTRS)

SS Cygni was observed by the ASCA satellite on 1993 May 27, the first cataclysmic variable studied by ASCA. The observations were conducted while the system was in an outburst of the 'anomalous' variety. The SIS spectrum cannot be explained by two-temperature Raymond-Smith coronal plasma models as invoked in previous studies with lower spectral resolution. Significantly better agreement is found for models with plasma emission at kT = 0.8, 3.5 keV and thermal bremsstrahlung at kT = 18 keV. The gas imaging spectrometer (GIS) data are consistent with the solid state imaging spectrometer (SIS) data, showing evidence for Fe line emission but showing no evidence of pulsation over times ranging from seconds to minutes. These observations seem at variance with standard theory in two regards: we simultaneously see hard X-rays and optically thin soft X-rays while the system is in outburst, and we see a nonsmooth emission measure distribution. We speculate on possible scenarios which might resolve these differences.

Nousek, John A.; Baluta, Christopher J.; Corbet, Robin H. D.; Mukai, Koji; Osborne, Julian P.; Ishida, Manabu

1994-01-01

370

MICROWAVE RESONANCES IN DNA  

EPA Science Inventory

This report describes spectroscopic studies of DNA which were undertaken to better understand a physical basis for microwave absorption by this molecule. hree types of studies are described. ) The low frequency scattered light spectrum of DNA was studied by two methods. irst, Ram...

371

Local microwave background radiation  

E-print Network

An inquiry on a possible local origin for the Microwave Background Radiation is made. Thermal MBR photons are contained in a system called {\\it magnetic bottle} which is due to Earth magnetic field and solar wind particles, mostly electrons. Observational tests are anticipated.

Domingos S. L. Soares

2006-07-11

372

Hybrid Microwave Technology  

SciTech Connect

A team associated with a Federal Laboratory, academia, and industry has been actively developing new microwave technology for treatment and remediation of a variety of potentially hazardous materials for almost a decade. This collaboration has resulted in unique equipment and processes with potential applicability to many fields, including disposition of electronic circuitry and components, medical wastes, radioactive materials and recycling of used tires.

Wicks, G.G.

2001-03-07

373

Satellite microwave remote sensing  

SciTech Connect

This work discusses satellite remote sensing with global applications. Presents and assesses the research findings of the SEASAT Users Group of Europe which carried out experiments over European sites. Studies the sea surface, carrying high resolution microwave sensors, providing day and night coverage of weather.

Allen, T.D.

1983-01-01

374

Anomalous hydrodynamics kicks neutron stars  

E-print Network

Observations show that, at the beginning of their existence, neutron stars are accelerated briskly to velocities of up to $1000$ km/s. We discuss possible mechanisms contributing to these kicks in a systematic effective-field-theory framework. Anomalies of the underlying microscopic theory result in chiral transport terms in the hydrodynamic description, and we identify these as explanation for the drastic acceleration. In the presence of vorticity or a magnetic field, the chiral transport effects cause neutrino emission along the respective axes. In typical scenarios, the transport effect due to the magnetic field turns out to be strong enough to explain the kicks. Mixed gauge-gravitational anomalies enter in a distinct way, and we also discuss their implications.

Kaminski, Matthias; Bleicher, Marcus; Schaffner-Bielich, Jürgen

2014-01-01

375

'Complexity' and Anomalous Transport in Space Plasmas  

NASA Technical Reports Server (NTRS)

"Complexity" has become a hot topic in nearly every field of modern physics. Space plasma is of no exception. In this paper, it is demonstrated that the sporadic and localized interactions of magnetic coherent structures are the origin of complexity in space plasmas. The intermittent localized interactions, which generate the anomalous diffusion, transport, and evolution of the macroscopic state variables of the overall dynamical system, may be modeled by a triggered (fast) localized chaotic growth equation of a set of relevant order parameters. Such processes would generally pave the way for the global system to evolve into a complex state of long-ranged interactions of fluctuations. displaying the phenomenon of forced and/or self-organized criticality. An example of such type of anomalous transport and evolution in a sheared magnetic field is provided via two-dimensional magnetohydrodynamic simulations. The coarse-grained dissipation due to the intermittent triggered interactions among the magnetic coherent structures induces a "fluctuation-induced nonlinear instability" that reconfigures the sheared magnetic field into an x-point magnetic geometry (in the mean field sense), leading to the anomalous acceleration of the magnetic coherent structures. A phenomenon akin to such type of anomalous transport and acceleration. The so-called bursty bulk flows, has been commonly observed in the plasma sheet of the Earth's magnetotail.

Wu, Cheng-Chin; Chang, Tom

2002-01-01

376

Anomalous dissolution of metals and chemical corrosion  

Microsoft Academic Search

An overview is given of the anomalous behavior of some metals, in particular Fe and Cr, in acidic aqueous solutions during anodic dissolution. The anomaly is recog- nizable by the fact that during anodic dissolution more material dissolves than would be expected from the Faraday law with the use of the expected valence of the formed ions. Mechanical disintegration, gas

Dragutin Drazic; JOVAN P. POPI

2005-01-01

377

The anomalous component: observations, theory and implications  

Microsoft Academic Search

The recent progress concerning the knowledge about the physics of Anomalous Cosmic Rays (ACRs) will be reviewed. In contrast to earlier expectations -from before the Voyager space-craft crossed the solar wind termination shock and started to observe the (inner) heliosheath in-situ -it remains unclear where ACRs are accelerated and which process is responsible for it. Of particluar interest is, therefore,

Horst Fichtner

2010-01-01

378

Anomalous Hall Effect for chiral fermions  

E-print Network

Semiclassical chiral fermions manifest the anomalous spin-Hall effect: when put into a pure electric field, they suffer a side jump, analogous to what happens to their massive counterparts in non-commutative mechanics. The transverse shift is consistent with the conservation of the angular momentum. In a pure magnetic field a cork-screw-like, spiraling motion is found.

Zhang, P -M

2014-01-01

379

Defusing Intrusion Capabilities by Collaborative Anomalous Trust  

Microsoft Academic Search

From a computer security perspective, services provided by distributed information systems may be organized based on their security attributes goals and requirements; these processes and services are categorized as anonymous, registered, encrypted and trusted. In this research, we propose a solution for operational trust assurance problems where vulnerabilities reduction is implicitly observed. Collaborative anomalous trust management (CATM) is a methodology

Khalil A. Abuosba; Clemens Martin

2008-01-01

380

Detecting anomalous access patterns in relational databases  

Microsoft Academic Search

A considerable effort has been recently devoted to the development of Database Management Systems (DBMS) which guarantee high assurance and security. An important component of any strong security solution is repre- sented by Intrusion Detection (ID) techniques, able to detect anomalous behavior of applications and users. To date, how- ever, there have been few ID mechanisms proposed which are specifically

Ashish Kamra; Evimaria Terzi; Elisa Bertino

2008-01-01

381

ANOMALOUS RADIOCARBON DATES FROM EASTER ISLAND  

Microsoft Academic Search

The largest volcanic crater on Easter Island in the South Pacific contains a lake 1 km in diameter with large floating mats of vegetation, mainly Scirpus californicus. A core taken through a mat near the center produced anomalous dates, with older dates above younger ones. The possibility that the mat had become inverted was considered, but palynolog- ical evidence refutes

Kevin Butler; Christine A Prior; John R Flenley

382

RSRM Nozzle Anomalous Throat Erosion Investigation Overview  

NASA Technical Reports Server (NTRS)

In September, 1996, anomalous pocketing erosion was observed in the aft end of the throat ring of the nozzle of one of the reusable solid rocket motors (RSRM 56B) used on NASA's space transportation system (STS) mission 79. The RSRM throat ring is constructed of bias tape-wrapped carbon cloth/ phenolic (CCP) ablative material. A comprehensive investigation revealed necessary and sufficient conditions for occurrence of the pocketing event and provided rationale that the solid rocket motors for the subsequent mission, STS-80, were safe to fly. The nozzles of both of these motors also exhibited anomalous erosion similar to, but less extensive than that observed on STS-79. Subsequent to this flight, the investigation to identify both the specific causes and the corrective actions for elimination of the necessary and sufficient conditions for the pocketing erosion was intensified. A detailed fault tree approach was utilized to examine potential material and process contributors to the anomalous performance. The investigation involved extensive constituent and component material property testing, pedigree assessments, supplier audits, process audits, full scale processing test article fabrication and evaluation, thermal and thermostructural analyses, nondestructive evaluation, and material performance tests conducted using hot fire simulation in laboratory test beds and subscale and full scale solid rocket motor static test firings. This presentation will provide an over-view of the observed anomalous nozzle erosion and the comprehensive, fault-tree based investigation conducted to resolve this issue.

Clinton, R. G., Jr.; Wendel, Gary M.

1998-01-01

383

Anomalous solutions to the strong CP problem  

E-print Network

We present a new mechanism for solving the strong CP problem using a Z2 discrete symmetry and an anomalous U(1) symmetry. A Z2 symmetry is used so that two gauge groups have the same theta angle. An anomalous U(1) symmetry makes the difference between the two theta angles physical and the sum unphysical. Two models are presented where the anomalous symmetry manifests itself in the IR in different ways. In the first model there are massless bifundamental quarks, a solution reminiscent of the massless up quark solution. In the IR of this model, the $\\eta'$ boson relaxes the QCD theta angle to the difference between the two theta angles - in this case zero. In the second model, the anomalous U(1) symmetry is realized in the IR as a dynamically generated mass term that has exactly the phase needed to cancel the theta angle. Both of these models make the extremely concrete prediction that there exist new colored particles at the TeV scale.

Hook, Anson

2014-01-01

384

Development of anomalous diffusion among crowding proteins  

E-print Network

In cell membranes, proteins and lipids diffuse in a highly crowded and heterogeneous landscape, where aggregates and dense domains of proteins or lipids obstruct the path of diffusing molecules. In general, hindered motion gives rise to anomalous transport, though the nature of the onset of this behavior is still under debate and difficult to investigate experimentally. Here, we present a systematic study where proteins bound to supported lipid membranes diffuse freely in two dimensions, but are increasingly hindered by the presence of other like proteins. In our model system, the surface coverage of the protein avidin on the lipid bilayer is well controlled by varying the concentration of biotinylated lipid anchors. Using fluorescence correlation spectroscopy (FCS), we measure the time correlation function over long times and convert it to the mean-square displacement of the diffusing proteins. Our approach allows for high precision data and a clear distinction between anomalous and normal diffusion. It enables us to investigate the onset of anomalous diffusion, which takes place when the area coverage of membrane proteins increases beyond approximately 5%. This transition region exhibits pronounced spatial heterogeneities. Increasing the packing fraction further, transport becomes more and more anomalous, manifested in a decrease of the exponent of subdiffusion.

Margaret R. Horton; Felix Höfling; Joachim O. Rädler; Thomas Franosch

2010-03-19

385

Experimental Demonstration of a Tunable Microwave Undulator  

NASA Astrophysics Data System (ADS)

Static magnetic undulators used by x-ray light sources are fundamentally too limited to achieve shorter undulator periods and dynamic control. To overcome these limitations, we report experimental demonstration of a novel short-period microwave undulator, essentially a Thomson scattering device, that has yielded tunable spontaneous emission and seeded coherent radiation. Its equivalent undulator period (?u) is 13.9 mm while it has achieved an equivalent magnetic field of 0.65 T. For future-generation light sources, this device promises a shorter undulator period, a large aperture, and fast dynamic control.

Tantawi, Sami; Shumail, Muhammad; Neilson, Jeffery; Bowden, Gordon; Chang, Chao; Hemsing, Erik; Dunning, Michael

2014-04-01

386

Microwave power tubes for space applications  

NASA Technical Reports Server (NTRS)

Feasibility evaluations of klystron amplifiers for conversion of solar power in synchronous orbit into microwave power at 2.4 GHz and transmission to earth were carried out. It was found that amplitrons and klystrons, using a depressed collector augmentation, can achieve efficiencies in excess of 80% if the power output is kept higher than 50 kW. Body wound selenoid provides the needed beam-focusing field. Narrow bandwidth requirements permit a low cathode loading density of 0.5 A/sq cm produced at approximately 850 centigrades. Emission tests indicate a potential life expectancy of 20 to 40 years.

Kosmahl, H.

1976-01-01

387

Characteristics of atmospheric pressure microwave plasma torch  

NASA Astrophysics Data System (ADS)

Atmospheric pressure microwave (2.45 GHz) plasma torch has been designed and built. The plasma optical and electrical characteristic have been investigated. The data has been compared with the kHz frequency rf torch. Electron temperature, density and gas temperatures are measured for different flow rates and for different gases. Optical emission spectrometer and ICCD camera are used to measure the argon and helium plasma characteristics and the results are compared for both designs. This Work has been supported by TUBITAK TEYDEB project no:9100036

Bozduman, Ferhat; Teke, Erdogan; Gulec, Ali; Oksuz, Lutfi

2012-10-01

388

The reappearance of the anomalous oxygen component at 1 AU  

NASA Technical Reports Server (NTRS)

The anomalous oxygen component was observed to reappear at the ICE spacecraft at 1 AU in the period 1 Mar. - 1 May 1986. The prediction of a strong decrease in intensity of the anomalous component in alternate solar cycles is not borne out. The observations suggest that the anomalous component is singly charged in accordance with the predictions of Fisk et al.

Vonrosenvinge, T. T.; Reames, D. V.

1987-01-01

389

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

390

NLO BFKL and Anomalous Dimensions of Light-Ray Operators  

SciTech Connect

The anomalous dimensions of light-ray operators of twist two are obtained by analytical continuation of the anomalous dimensions of corresponding local operators. I demonstrate that the asymptotics of these anomalous dimensions at the "BFKL point" j ? 1 can be obtained by comparing the light-cone operator expansion with the high-energy expansion in Wilson lines.

Balitsky, Ian [JLAB, Newport News, VA (United States)

2014-01-01

391

Fingerprints of Galactic Loop I on the Cosmic Microwave Background  

E-print Network

We investigate possible imprints of galactic foreground structures such as the `radio loops' in the derived maps of the cosmic microwave background. Surprisingly there is evidence for these not only at radio frequencies through their synchrotron radiation, but also at microwave frequencies where emission by dust dominates. This suggests the mechanism is magnetic dipole radiation from dust grains enriched by metallic iron, or ferrimagnetic molecules. This new foreground we have identified is present at high galactic latitudes, and potentially dominates over the expected B-mode polarisation signal due to primordial gravitational waves from inflation.

Liu, Hao; Sarkar, Subir

2014-01-01

392

Fan-shaped microwave plasma for mail decontamination  

NASA Astrophysics Data System (ADS)

A microwave torch is designed to produce fan-shaped plasma, which extends about 140 mm laterally. This torch produces an abundance of reactive atomic oxygen in the plasma effluent as evidenced by its emission spectroscopy. The results of the spectral intensity measurements show that the produced atomic oxygen outside the microwave cavity distributes quite uniformly over a width of about 80 mm and reaches out more than 10 mm. An experiment applying this plasma to kill Bacillus cereus contained in an envelope has been performed. The kill rate is presented.

Kuo, Spencer P.; Popovic, S.; Tarasenko, Olga; Rubinraut, M.; Raskovic, M.

2007-08-01

393

FUSING MICROWAVE RADAR AND MICROWAVE-INDUCED THERMOACOUSTICS FOR BREAST CANCER DETECTION  

E-print Network

FUSING MICROWAVE RADAR AND MICROWAVE-INDUCED THERMOACOUSTICS FOR BREAST CANCER DETECTION Evgeny and Computer Engineering, McGill University, H3A 2A7, Montreal, QC, Canada ABSTRACT Microwave-based techniques in the microwave range. Microwave-radar and microwave-induced thermoacoustic methods both struggle when

394

Sea surface temperature estimation using active and passive microwave remote sensing  

NASA Astrophysics Data System (ADS)

Although sea surface temperature (SST) is often estimated from satellite infrared observations, passive microwave techniques have the advantage of being applicable in cloudy regions. The goal of this research is to combine active and passive microwave measurements to improve the accuracy of the SST retrievals. A non-linear iterative inversion method for the retrieval of surface wind (U) and sea surface temperature (SST) using space-borne microwave scatterometer and radiometer measurements is developed and applied to data collected by the SeaSat satellite. This retrieval algorithm is physically based, using an integrated microwave model for normalized radar cross section (?0) and surface emissivity and a nonlinear least squares estimation technique. The ?0 model is empirical, based on a SeaSat data set; While the emissivity model is physically-based. In the emissivity model the microwave reflectance R is estimated using the ocean wave spectrum of Bjerkaas and Reidel and a bistatic two-scale scattering model, and the microwave emissivity e is calculated as e=1-R where R is microwave reflectivity. The validity of this active and passive microwave algorithm is evaluated for the case of an eastern pacific test area employing 14.6 GHz SeaSat scatterometer (SASS) and 6.6 GHz V-pol radiometer (SMMR) data. The results show that SST can be reliably estimated from SeaSat SASS/SMMR measurements for an open ocean area. Two sets of SMMR cells were analyzed. The averaged test-site correlation coefficient between the reference SST (measured by ships) and the SeaSat-based estimates of SST is 0.8916 and the corresponding standard errors are smaller than 0.7oC. These results suggest that a physically based SST retrieval scheme can be useful in improving the accuracy of SST measurements made with passive microwave remote sensing.

Wang, Nai-Yu

395

Microwave Brightness Temperatures of Tilted Convective Systems  

NASA Technical Reports Server (NTRS)

Aircraft and ground-based radar data from the Tropical Ocean and Global Atmosphere Coupled-Ocean Atmosphere Response Experiment (TOGA COARE) show that convective systems are not always vertical. Instead, many are tilted from vertical. Satellite passive microwave radiometers observe the atmosphere at a viewing angle. For example, the Special Sensor Microwave/Imager (SSM/I) on Defense Meteorological Satellite Program (DMSP) satellites and the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) on the TRMM satellite have an incident angle of about 50deg. Thus, the brightness temperature measured from one direction of tilt may be different than that viewed from the opposite direction due to the different optical depth. This paper presents the investigation of passive microwave brightness temperatures of tilted convective systems. To account for the effect of tilt, a 3-D backward Monte Carlo radiative transfer model has been applied to a simple tilted cloud model and a dynamically evolving cloud model to derive the brightness temperature. The radiative transfer results indicate that brightness temperature varies when the viewing angle changes because of the different optical depth. The tilt increases the displacements between high 19 GHz brightness temperature (Tb(sub 19)) due to liquid emission from lower level of cloud and the low 85 GHz brightness temperature (Tb(sub 85)) due to ice scattering from upper level of cloud. As the resolution degrades, the difference of brightness temperature due to the change of viewing angle decreases dramatically. The dislocation between Tb(sub 19) and Tb(sub 85), however, remains prominent.

Hong, Ye; Haferman, Jeffrey L.; Olson, William S.; Kummerow, Christian D.

1998-01-01

396

Microwave kinetic inductance detectors  

NASA Astrophysics Data System (ADS)

Low temperature detectors have been a subject of intense interest to the scientific community over the last decade. These detectors work at very low temperatures, often well below 1 Kelvin, to minimize the noise in the measurement of photons. This leads to very powerful detectors applicable to a broad wavelength range. Since these detectors are so sensitive even single pixels and small arrays (up to several hundred pixels) enable deeper explorations of the cosmos than ever before. Instruments based on these technologies have been used at submillimeter, optical, and X-ray wavelengths. The scientific prospects for these detectors increase as they grow in pixel count. For some applications, especially for Cosmic Microwave Background (CMB) polarization work, a large focal plane will not only increase efficiency but will also enable new and vital science. Current superconducting technologies, such as Transition Edge Sensors (TESs), can currently deliver extremely high sensitivity in the submillimeter and read- noise free imaging spectroscopy at Optical/UV and X-ray wavelengths, but the largest arrays contain less that 100 pixels. In order to make real progress these arrays must contain many thousands of pixels. This is a formidable technical challenge. This thesis will explore a promising emerging technology called Microwave Kinetic Inductance Detectors (MKIDs). MKIDs make use of the change in the surface impedance of a superconductor as incoming photons break up Cooper pairs. This is accomplished by making the strip of superconductor part of a microwave resonant circuit, and monitoring the phase of a signal transmitted through (or past) the resonator. The primary advantage of this technology is that by using resonant circuits with high quality factors, passive frequency domain multiplexing will allow up to thousands of resonators to be read out through a single coaxial cable and a single HEMT amplifier. This eliminates the cryogenic electronics (SQUIDS) and wiring problems associated with current superconducting devices. Inexpensive and powerful room-temperature readout electronics can leverage the microwave integrated circuits developed for wireless communications.

Mazin, Benjamin A.

2005-11-01

397

Microwave blackbodies for spaceborne receivers  

NASA Technical Reports Server (NTRS)

The properties of microwave blackbody targets are explained as they apply to the calibration of spaceborne receivers. Also described are several practicable, blackbody targets used to test and calibrate receivers in the laboratory and in the thermal vacuum chamber. Problems with the precision and the accuracy of blackbody targets, and blackbody target design concepts that overcome some of the accuracy limitations present in existing target designs, are presented. The principle of the Brewster angle blackbody target is described where the blackbody is applied as a fixed-temperature test target in the laboratory and as a variable-temperature target in the thermal vacuum chamber. The reflectivity of a Brewster angle target is measured in the laboratory. From this measurement, the emissivity of the target is calculated. Radiatively cooled thermal suspensions are discussed as the coolants of blackbody targets and waveguide terminations that function as calibration devices in spaceborne receivers. Examples are given for the design of radiatively cooled thermal suspensions. Corrugated-horn antennas used to observe the cosmic background and to provide a cold-calibration source for spaceborne receivers are described.

Stacey, J. M.

1985-01-01

398

Cryogenic Microwave Anisotropic Artificial Frank Trang  

E-print Network

Cryogenic Microwave Anisotropic Artificial Materials by Frank Trang B.S., University of California entitled: Cryogenic Microwave Anisotropic Artificial Materials written by Frank Trang has been approved.D., Electrical Engineering) Cryogenic Microwave Anisotropic Artificial Materials Thesis directed by Professor

Popovic, Zoya

399

Resonant Compton Upscattering in Anomalous X-ray Pulsars  

E-print Network

A significant new development in the study of Anomalous X-ray Pulsars (AXPs) has been the recent discovery by INTEGRAL and RXTE of flat, hard X-ray components in three AXPs. These non-thermal spectral components differ dramatically from the steeper quasi-power-law tails seen in the classic X-ray band in these sources. A prime candidate mechanism for generating this new component is resonant, magnetic Compton upscattering. This process is very efficient in the strong magnetic fields present in AXPs. Here an introductory exploration of an inner magnetospheric model for upscattering of surface thermal X-rays in AXPs is offered, preparing the way for an investigation of whether such resonant upscattering can explain the 20-150 keV spectra seen by INTEGRAL. Characteristically flat emission spectra produced by non-thermal electrons injected in the emission region are computed using collision integrals. A relativistic QED scattering cross section is employed so that Klein-Nishina reductions are influential in determining the photon spectra and fluxes. Spectral results depend strongly on the magnetospheric locale of the scattering and the observer's orientation, which couple directly to the angular distributions of photons sampled.

Matthew G. Baring; Alice K. Harding

2006-10-12

400

Microwave NDE for Reinforced Concrete  

NASA Astrophysics Data System (ADS)

Nondestructive assessment of the integrity of civil structures is of paramount importance for ensuring safety. In concrete imaging, radiography, ground penetrating radar and infrared thermography are some of the widely used techniques for health monitoring. Other emerging technologies that are gaining impetus for detecting and locating flaws in steel reinforcement bar include radioactive computed tomography, microwave holography, microwave and acoustic tomography. Of all the emerging techniques, microwave NDT is a promising imaging modality largely due to their ability to penetrate thick concrete structures, contrast between steel rebar and concrete and their non-radioactive nature. This paper investigates the feasibility of a far field microwave NDE technique for reinforced concrete structures.

Arunachalam, Kavitha; Melapudi, Vikram R.; Rothwell, Edward J.; Udpa, Lalita; Udpa, Satish S.

2006-03-01

401

The Microwave SQUID Multiplexer  

NASA Astrophysics Data System (ADS)

This thesis describes a multiplexer of Superconducting Quantum Interference Devices (SQUIDs) with low-noise, ultra-low power dissipation, and great scalability. The multiplexer circuit measures the magnetic flux in a large number of unshunted rf SQUIDs by coupling each SQUID to a superconducting microwave resonator tuned to a unique resonance frequency and driving the resonators from a common feedline. A superposition of microwave tones measures each SQUID simultaneously using only two coaxial cables between the cryogenic device and room temperature. This multiplexer will enable the instrumentation of arrays with hundreds of thousands of low-temperature detectors for new applications in cosmology, materials analysis, and nuclear non-proliferation. The driving application of the Microwave SQUID Multiplexer is the readout of large arrays of superconducting transition-edge sensors, by some figures of merit the most sensitive detectors of electromagnetic signals over a span of more than nine orders of magnitude in energy, from 40 GHz microwaves to 200 keV gamma rays. Modern transition-edge sensors have noise-equivalent power as low as 10-20 W / Hz1/2 and energy resolution as good as 2 eV at 6 keV. These per-pixel sensitivities approach theoretical limits set by the underlying signals, motivating a rapid increase in pixel count to access new science. Compelling applications, like the non-destructive assay of nuclear material for treaty verification or the search for primordial gravity waves from inflation use arrays of these detectors to increase collection area or tile a focal plane. We developed three generations of SQUID multiplexers, optimizing the first for flux noise 0.17 muPhi0 / Hz1/2, the second for input current noise 19 pA / Hz1/2, and the last for practical multiplexing of large arrays of cosmic microwave background polarimeters based on transition-edge sensors. Using the last design we demonstrated multiplexed readout of prototype polarimeters with the performance required for the future development of a large-scale astronomical instrument.

Mates, John Arthur Benson

402

Spectrophotometric Properties of Thermally Anomalous Terrain on Mimas  

NASA Astrophysics Data System (ADS)

Cassini’s Composite InfraRed Spectrometer (CIRS) maps of thermal emission from Mimas reveal a V-shaped boundary, centered at 0° N and 180° W, which divides relatively warm daytime temperatures from an anomalously cooler region at low to mid-latitudes on the moon’s leading hemisphere (Howett et al. 2011, Icarus 216, 221-226). 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, JGRA 112, A06214; Schenk et al. 2011, Icarus 211, 740-757). Global IR/UV color ratio maps assembled from Cassini Imaging Science Subsystem (ISS) images show a lens-shaped region of relatively blue terrain also centered on Mimas’ leading hemisphere (Schenk et al. 2011), coinciding in shape and location with the region of high thermal inertia. We present results of our analysis of Cassini ISS CL1 UV3 and IR3 filter (centered at 338 and 930 nm, respectively) images using the Hapke (2008, Icarus 195, 918-926) photometric model. We investigate whether the photometric properties of surface particles are consistent with the conclusion by Howett et al. (2011) that their high thermal inertia is produced by sintering processes due to bombardment by high energy electrons. The non-thermally anomalous surface on Mimas' trailing hemisphere exhibits a strong opposition effect, consistent with the presence of a more complex microtexture due to preferential bombardment by E ring particles. This work is supported by the NASA Cassini Data Analysis and Participating Scientists Program.

Verbiscer, Anne J.; Helfenstein, Paul; Howett, Carly; Annex, Andrew; Schenk, Paul

2014-11-01

403

Discerning differences among anomalously wandering directed polymers  

NASA Astrophysics Data System (ADS)

We contrast the effects of uncorrelated power-law noise and linearly correlated Gaussian noise upon the anomalous wandering of directed polymers in random media. In the first instance, we explore the role of the noise on the morphology of the ultrametric tree structure of the ensemble of locally optimal paths, and then, motivated by the work of Zhang [Phys. Rev. Lett. 59, 2125 (1987)] and more recently by Perlsman and Schwartz [Europhys. Lett. 17, 11 (1992)], provide strong evidence for the universality of the model's river basin patterns. Lastly, we discuss those precise features of the positional and energy fluctuations that could permit a resourceful experimentalist to discern the noise distribution underlying anomalous roughening recently observed in fire fronts, bacterial growth, and fluid flow through porous media.

Pang, Ning-Ning; Halpin-Healy, Timothy

1993-02-01

404

Anomalous g^5_z coupling at $??$ colliders  

E-print Network

We study the constraints on the anomalous coupling $g^Z_5$ that can be obtained from the analysis of the reaction $\\gamma\\gamma \\rightarrow W^+ W^- Z$ at future linear $e^+e^-$ colliders. We find out that a $0.5$ ($1$) TeV $e^+e^-$ collider operating in the $\\gamma\\gamma$ mode can probe values of $g_5^Z$ of the order of $0.15$ ($4.5 \\times 10^{-2}$) for an integrated luminosity of $10$ fb$^{-1}$. This shows that the ability to search for this anomalous interaction of the $\\gamma\\gamma$ mode is better than the one of the usual $e^+e^-$ mode, and it is similar to the ability of the $e\\gamma$ mode.

O. J. P. Eboli; M. B. Magro; P. G. Mercadante

1995-08-07

405

Remote sensing and characterization of anomalous debris  

NASA Technical Reports Server (NTRS)

The analysis of orbital debris data shows a band of anomalously high debris concentration in the altitude range between 800 and 1000 km. Analysis indicates that the origin is the leaking coolant fluid from nuclear power sources that powered a now defunct Soviet space-based series of ocean surveillance satellites. A project carried out to detect, track and characterize a sample of the anomalous debris is reported. The nature of the size and shape of the sample set, and the possibility of inferring the composition of the droplets were assessed. The technique used to detect, track and characterize the sample set is described and the results of the characterization analysis are presented. It is concluded that the nature of the debris is consistent with leaked Na-K fluid, although this cannot be proved with the remote sensing techniques used.

Sridharan, R.; Beavers, W.; Lambour, R.; Gaposchkin, E. M.; Kansky, J.; Stansbery, E.

1997-01-01

406

Anomalous Dynamics of DNA Hairpin Folding  

NASA Astrophysics Data System (ADS)

By means of computer simulations of a coarse-grained DNA model we show that the DNA hairpin zippering dynamics is anomalous; i.e., the characteristic time ? scales nonlinearly with N, the hairpin length, ?˜N? with ?>1. This is in sharp contrast to the prediction of the zipper model for which ?˜N. We show that the anomalous dynamics originates from an increase in the friction during zippering due to the tension built in the closing strands. From a simple polymer model we get ?=1+??1.59 with ? being the Flory exponent, a result which is in agreement with the simulations. We discuss transition path times data where such effects should be detected.

Frederickx, R.; in't Veld, T.; Carlon, E.

2014-05-01

407

Anomalous Cherenkov spin-orbit sound  

SciTech Connect

The Cherenkov effect is a well-known phenomenon in the electrodynamics of fast charged particles passing through transparent media. If the particle is faster than the light in a given medium, the medium emits a forward light cone. This beautiful phenomenon has an acoustic counterpart where the role of photons is played by phonons and the role of the speed of light is played by the sound velocity. In this case the medium emits a forward sound cone. Here, we show that in a system with spin-orbit interactions in addition to this normal Cherenkov sound there appears an anomalous Cherenkov sound with forward and backward sound propagation. Furthermore, we demonstrate that the transition from the normal to anomalous Cherenkov sound happens in a singular way at the Cherenkov cone angle. The detection of this acoustic singularity therefore represents an alternative experimental tool for the measurement of the spin-orbit coupling strength.

Smirnov, Sergey [Institut fuer Theoretische Physik, Universitaet Regensburg, D-93040 Regensburg (Germany)

2011-02-15

408

Synergistic use of optical and microwave data in agrometeorological applications  

NASA Technical Reports Server (NTRS)

Remotely sensed optical and microwave data can be synergistically used to infer land surface properties. Optical data can be used to estimate surface albedo, radiation absorption by vegetation canopies and their photosynthetic efficiencies. Vegetation canopy reflectance at red and near-infrared wavelengths can be used to correct for vegetation effect on microwave emissivities at low frequencies for estimating soil moisture. Optical data can also provide information about surface and air temperatures, precipitable water vapor, cloud top temperature and its water content. This information can be utilized to correct microwave data for atmospheric effects. These points are illustrated with theoretical analyses and by application to satellite data. The basic physical mechanisms operative at the various wavelengths are also discussed.

Myneni, R. B.; Choudhury, B. J.

1993-01-01

409

Dynamics of anomalous optical transitions in AlxGa1-xN alloys  

NASA Astrophysics Data System (ADS)

We present a comprehensive study of the optical characteristics of AlxGa1-xN epilayers (0<=x<=0.6) by means of photoluminescence (PL), PL excitation, and time-resolved PL spectroscopy. For AlxGa1-xN with large Al content, we observed an anomalous PL temperature dependence: (i) an ``S-shaped'' PL peak energy shift (decrease-increase-decrease) and (ii) an ``inverted S-shaped'' spectral width broadening (increase-decrease-increase) with increasing temperature. We observed that the thermal decrease in integrated PL intensity was suppressed and the effective lifetime was enhanced in the temperature region showing the anomalous temperature-induced emission behavior, reflecting superior luminescence efficiency by suppressing nonradiative processes. All these features were enhanced as the Al mole fraction was increased. From these results, the anomalous temperature-induced emission shift is attributed to energy tail states due to alloy potential inhomogeneities in the AlxGa1-xN epilayers with large Al content.

Cho, Yong-Hoon; Gainer, G. H.; Lam, J. B.; Song, J. J.; Yang, W.; Jhe, W.

2000-03-01

410

“Anomalous” collisionality in low-pressure plasmas  

SciTech Connect

Based on a theoretical argument from fundamental kinetic theory, by way of simple worked examples, and through the use of particle-in-cell simulations of capacitively coupled plasmas, we demonstrate that conventional methods for calculating the momentum transfer collision frequency in low-pressure plasmas can be seriously erroneous. This potentially plays an important and previously unconsidered role in many low-pressure discharges, and at least in part provides a possible explanation for anomalous behaviour often encountered in these plasmas.

Lafleur, T.; Chabert, P.; Booth, J. P. [LPP-CNRS, Ecole Polytechnique, 91128 Palaiseau (France)] [LPP-CNRS, Ecole Polytechnique, 91128 Palaiseau (France); Turner, M. M. [School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland)] [School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland)

2013-12-15

411

A new physical foundation for anomalous gravity  

Microsoft Academic Search

The rigorous relation between the sought subsurface anomalous density distribution and the gravity anomaly, the gravity disturbance,\\u000a and the geoidal height is newly reviewed. The emphasis is put on the proper treatment of the respective effects of topographical\\u000a masses. The aim is to prove, that the rigorous formulation of the above mentioned relations calls for using such topographical\\u000a corrections that

P. Vajda; P. Vanícek; B. Meurers

2006-01-01

412

The anomalous diffusion of meteor trails  

Microsoft Academic Search

Abstract. Radars frequently detect meteor trails created bythe,ablation of micro-meteoroids between70 and120 km altitude in the atmosphere. Plasma simulations show that densitygradientsattheedgesofmeteortrailsdrivegradient- drift instabilities which develop into waves with perturbed electric elds often exceeding hundreds of mV\\/m. These waves create an anomalous,cross-eld diusion that can ex- ceed the cross-eld (? B) ambipolar diusion,by an order of magnitude. The characteristics of

Lars P. Dyrud; Meers M. Oppenheim; Axel F. vom Endt

2001-01-01

413

Normal and Anomalous Diffusion: A Tutorial  

E-print Network

The purpose of this tutorial is to introduce the main concepts behind normal and anomalous diffusion. Starting from simple, but well known experiments, a series of mathematical modeling tools are introduced, and the relation between them is made clear. First, we show how Brownian motion can be understood in terms of a simple random walk model. Normal diffusion is then treated (i) through formalizing the random walk model and deriving a classical diffusion equation, (ii) by using Fick's law that leads again to the same diffusion equation, and (iii) by using a stochastic differential equation for the particle dynamics (the Langevin equation), which allows to determine the mean square displacement of particles. (iv) We discuss normal diffusion from the point of view of probability theory, applying the Central Limit Theorem to the random walk problem, and (v) we introduce the more general Fokker-Planck equation for diffusion that includes also advection. We turn then to anomalous diffusion, discussing first its formal characteristics, and proceeding to Continuous Time Random Walk (CTRW) as a model for anomalous diffusion. It is shown how CTRW can be treated formally, the importance of probability distributions of the Levy type is explained, and we discuss the relation of CTRW to fractional diffusion equations and show how the latter can be derived from the CTRW equations. Last, we demonstrate how a general diffusion equation can be derived for Hamiltonian systems, and we conclude this tutorial with a few recent applications of the above theories in laboratory and astrophysical plasmas.

Loukas Vlahos; Heinz Isliker; Yannis Kominis; Kyriakos Hizanidis

2008-05-05

414

Anomalous diffusion induced by enhancement of memory.  

PubMed

We introduced simple microscopic non-Markovian walk models which describe the underlying mechanism of anomalous diffusions. In the models, we considered the competitions between randomness and memory effects of previous history by introducing the probability parameters. The memory effects were considered in two aspects: one is the perfect memory of whole history and the other is the latest memory enhanced with time. In the perfect memory model superdiffusion was induced with the relation of the Hurst exponent H to the controlling parameter p as H = p for p>1/2, while in the latest memory enhancement models, anomalous diffusions involving both superdiffusion and subdiffusion were induced with the relations H = (1+?)/2 and H = (1-?)/2 for 0 ? ? ? 1, where ? is the parameter controlling the degree of the latest memory enhancement. Also we found that, although the latest memory was only considered, the memory improved with time results in the long-range correlations between steps and the correlations increase as time goes on. Thus we suggest the memory enhancement as a key origin describing anomalous diffusions. PMID:25122247

Kim, Hyun-Joo

2014-07-01

415

Anomalous Circular Polarization Profiles in Sunspot Chromospheres  

NASA Astrophysics Data System (ADS)

This paper presents a detailed description, analysis, and interpretation of the spectropolarimetric observations recently reported by Socas-Navarro, Trujillo Bueno, & Ruiz Cobo. These observations consist of time series of Stokes I and V profiles above a sunspot umbra. The spectral lines observed simultaneously are the Ca II chromospheric lines at 8498 and 8542 Å and the photospheric Fe I line at 8497 Å. These spectropolarimetric observations unveil an intriguing time-dependent behavior of the Stokes V profiles in the chromospheric lines. This behavior should be considered as an observational reference for future radiation magnetohydrodynamic simulations of sunspot chromospheres. The analysis of the observed time series shows that a ``normal,'' nearly antisymmetric V profile rapidly evolves toward an ``anomalous,'' completely asymmetric profile, returning later to the normal state. The occurrence of such anomalous circular polarization profiles repeats itself with a periodicity of ~150 s. After giving arguments to discard other scenarios, we are able to interpret the anomalous V profiles as a consequence of the development of a second unresolved atmospheric component. This unresolved component seems to be the same that produces the umbral flashes observed in other sunspots, where it is present with a larger filling factor. Based on observations obtained with the Gregory Coudé Telescope, operated on the island of Tenerife by the Observatory of Göttingen University, in the Spanish Observatorio del Teide of the Instituto de Astrofísica de Canarias.

Socas-Navarro, H.; Trujillo Bueno, J.; Ruiz Cobo, B.

2000-12-01

416

Anomalous and resonance small angle scattering: Revision  

SciTech Connect

Significant changes in the small angle scattered intensity can be induced by making measurements with radiation close to an absorption edge of an appropriate atomic species contained in the sample. These changes can be related quantitatively to the real and imaginary anomalous dispersion terms for the scattering factor (x-rays) or scattering length (neutrons). The physics inherent in these anomalous dispersion terms is first discussed before considering how they enter the relevant scattering theory. Two major areas of anomalous scattering research have emerged; macromolecules in solution and unmixing of metallic alloys. Research in each area is reviewed, illustrating both the feasibility and potential of these techniques. All the experimental results reported to date have been obtained with x-rays. However, it is pointed out that the formalism is the same for the analogue experiment with neutrons, and a number of suitable isotopes exist which exhibit resonance in an accessible range of energy. Potential applications of resonance small angle neutron scatterings are discussed. 54 refs., 8 figs., 1 tab.

Epperson, J.E.; Thiyagarajan, P.

1987-11-01

417

A Flat Universe from High-Resolution Maps of the Cosmic MicrowaveBackground Radiation  

SciTech Connect

The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K Cosmic Microwave Background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and find a peak at Legendre multipole {ell}{sub peak} = (197 {+-} 6), with an amplitude DT{sub 200} = (69 {+-} 8){mu}K. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favored by standard inflationary scenarios.

de Bernardis, P.; Ade, P.A.R.; Bock, J.J.; Bond, J.R.; Borrill,J.; Boscaleri, A.; Coble, K.; Crill, B.P.; De Gasperis, G.; Farese, P.C.; Ferreira, P.G.; Ganga, K.; Giacometti, M.; Hivon, E.; Hristov, V.V.; Iacoangeli, A.; Jaffe, A.H.; Lange, A.E.; Martinis, L.; Masi, S.; Mason,P.; Mauskopf, P.D.; Melchiorri, A.; Miglio, L.; Montroy, T.; Netterfield,C.B.; Pascale, E.; Piacentini, F.; Pogosyan, D.; Prunet, S.; Rao, S.; Romeo, G.; Ruhl, J.E.; Scaramuzzi, F.; Sforna, D.; Vittorio, N.

2000-04-28

418

Attenuation of microwaves propagating through parallel-plate helium glow discharge at atmospheric pressure  

SciTech Connect

The experimental study of microwave-plasma interaction has been performed to demonstrate the transmission and attenuation of microwaves in atmospheric pressure glow discharge plasma. The cold-collisional plasma produced at atmospheric pressure can absorb the microwave energy because of its complex dielectric constant. The microwave of 10 GHz frequency was launched into the plasma and attenuation was measured as a function of electron plasma density, plasma thickness, electron-neutral collision frequency, etc. It was observed that the attenuation significantly depends on electron plasma density and thickness. The microwave attenuation measurement was also used as a diagnostic to estimate electron plasma density. It was validated by optical emission spectroscopic measurements with helium line intensity ratio method. Both the methods show good agreement.

Srivastava, A. K.; Prasad, G.; Atrey, P. K.; Kumar, Vinay [Institute for Plasma Research, Bhat, Near Indira Bridge, Gandhinagar, Gujarat 382428 (India)

2008-02-01

419

The shadow of light: Lorentz invariance and complementarity principle in anomalous photon behaviour  

E-print Network

We review the results of two double-slit-like experiments in the infrared range, which evidence an anomalous behaviour of photon systems under particular (energy and space) constraints. These outcomes (independently confirmed by crossing photon beam experiments in both the optical and the microwave range) apparently rule out the Copenhagen interpretation of the quantum wave, i.e. the probability wave, by admitting an interpretation in terms of the Einstein-de Broglie-Bohm hollow wave for photons. Moreover, these experiments support the interpretation of the hollow wave as a deformation of the Minkowski space-time geometry. We stress the implications of these experimental results and of their interpretation for the concept of action-at-a-distance, the Einstein relativistic correlation and the Bohr principle of complementarity.

F. Cardone; R. Mignani; W. Perconti; A. Petrucci; R. Scrimaglio

2005-04-17

420

Anomalous Temperature Dependence of the Quality Factor in a Superconducting Coplanar Waveguide Resonator  

NASA Astrophysics Data System (ADS)

We present the measurements of the temperature dependence of the internal quality factor (Qi) of a microwave resonator, well below the superconducting transition temperature. The device is a quarter-wavelength niobium (Tc = 9.2 K) coplanar waveguide resonator. The measured |S21| parameter shows typically the skewed Lorentzian distributions, from which the fitted quality factor monotonically decreases with the temperature increasing from 30 mK to 900 mK. It is observed that for the lower temperature range (i.e., at T < 700 mK) the temperature dependence of the fitted Qi deviates significantly from the predictions of the usual Mattis—Bardeen theory. The measured 3 dB internal quality factor Q'i also verifies such an anomalous temperature dependence. Physically, this phenomenon could be attributed dominantly to the effects of the two-level systems in the device, rather than the usual temperature-dependent complex conductance.

Zhou, Pin-Jia; Wang, Yi-Wen; Wei, Lian-Fu

2014-06-01

421

High-beta effects and anomalous diffusion in plasmas expanding into magnetic fields  

NASA Technical Reports Server (NTRS)

A metallic laser-produced plasma is allowed to expand transversely into an applied magnetic field, under conditions where the typical ion cyclotron radius is much larger, and the electron cyclotron radius much smaller, than the experimental dimensions. A stationary background plasma may also be present. Initially, the flow energy density exceeds (B squared/8 times pi), where B is the ambient magnetic field. Magnetic coil probes, Langmuir probes, and microwave diagnostics are used to study the plasma-field interaction. Field compression at the leading edge and field exclusion within the expanding plasma are seen. The diagnostic measurements and comparison with a theoretical model demonstrate plasma turbulence and anomalously high diffusion of field into the expanding plasma.

Koopman, D. W.

1976-01-01

422

A Biological Interpretation of Transient Anomalous Subdiffusion. I. Qualitative Model  

PubMed Central

Anomalous subdiffusion has been reported for two-dimensional diffusion in the plasma membrane and three-dimensional diffusion in the nucleus and cytoplasm. If a particle diffuses in a suitable infinite hierarchy of binding sites, diffusion is well known to be anomalous at all times. But if the hierarchy is finite, diffusion is anomalous at short times and normal at long times. For a prescribed set of binding sites, Monte Carlo calculations yield the anomalous diffusion exponent and the average time over which diffusion is anomalous. If even a single binding site is present, there is a very short, almost artifactual, period of anomalous subdiffusion, but a hierarchy of binding sites extends the anomalous regime considerably. As is well known, an essential requirement for anomalous subdiffusion due to binding is that the diffusing particle cannot be in thermal equilibrium with the binding sites; an equilibrated particle diffuses normally at all times. Anomalous subdiffusion due to barriers, however, still occurs at thermal equilibrium, and anomalous subdiffusion due to a combination of binding sites and barriers is reduced but not eliminated on equilibration. This physical model is translated directly into a plausible biological model testable by single-particle tracking. PMID:17142285

Saxton, Michael J.

2007-01-01

423

Effects of corn stalk orientation and water content on passive microwave sensing of soil moisture  

NASA Technical Reports Server (NTRS)

A field experiment was conducted utilizing artificial arrangements of plant components during the summer of 1982 to examine the effects of corn canopy structure and plant water content on microwave emission. Truck-mounted microwave radiometers at C (5 GHz) and L (1.4 GHz) band sensed vertically and horizontally polarized radiation concurrent with ground observations of soil moisture and vegetation parameters. Results indicate that the orientation of cut stalks and the distribution of their dielectric properties through the canopy layer can influence the microwave emission measured from a vegetation/soil scene. The magnitude of this effect varies with polarization and frequency and with the amount of water in the plant, disappearing at low levels of vegetation water content. Although many of the canopy structures and orientations studied in this experiment are somewhat artificial, they serve to improve understanding of microwave energy interactions within a vegetation canopy and to aid in the development of appropriate physically based vegetation models.

Oneill, P. E.; Blanchard, B. J.; Wang, J. R.; Gould, W. I.; Jackson, T. J.

1984-01-01

424

Microwave Signatures of Snow on Sea Ice: Modeling  

NASA Technical Reports Server (NTRS)

Accurate knowledge of snow-depth distribution over sea ice is critical for polar climate studies. Current snow-depth-over-sea-ice retrieval algorithms do not sufficiently account for variations in snow and ice physical properties that can affect the accuracy of retrievals. For this reason, airborne microwave observations were coordinated with ground-based measurements of snow depth and snow properties in the vicinity of Barrow, AK, in March 2003. In this paper, the effects of snowpack properties and ice conditions on microwave signatures are examined using detailed surface-based measurements and airborne observations in conjunction with a thermal microwave-emission model. A comparison of the Microwave Emission Model of Layered Snowpacks (MEMLS) simulations with detailed snowpack and ice data from stakes along the Elson Lagoon and the Beaufort Sea and ra- 'diometer data taken from low-level flights using a Polarimetric Scanning Radiometer (PSR-A) shows that MEMLS can be used to simulate snow on sea ice and is a useful tool for understanding the limitations of the snow-depth algorithm. Analysis of radiance data taken over the Elson Lagoon and the Beaufort Sea using MEMLS suggests that the radiometric differences between the two locations are due to the differences in sea-ice emissivity. Furthermore, measured brightness temperatures suggest that the current snow-depth retrieval algorithm is sufficient for areas of smooth first-year sea ice, whereas new algorithm coefficients are needed for rough first-year sea ice. Snowpack grain size and density remain an unresolved issue for snow-depth retrievals using passive-microwave radiances.

Powell, D. C.; Markus, T.; Cavalieri, D. J.; Gasiewski, A. J.; Klein, M.; Maslanik, J. A.; Stroeve, J. C.; Sturm, M.

2006-01-01

425

Microwave and Pulsed Power  

SciTech Connect

The goals of the Microwave and Pulsed Power thrust area are to identify realizable research and development efforts and to conduct high-quality research in those pulse power and microwave technologies that support existing and emerging programmatic requirements at Lawrence Livermore National Laboratory (LLNL). Our main objective is to work on nationally important problems while enhancing our basic understanding of enabling technologies such as component design and testing, compact systems packaging, exploratory physics experiments, and advanced systems integration and performance. During FY-92, we concentrated our research efforts on the six project areas described in this report. (1) We are investigating the superior electronic and thermal properties of diamond that may make it an ideal material for a high-power, solid-state switch. (2) We are studying the feasibility of using advanced Ground Penetrating Imaging Radar technology for reliable non-destructive evaluation of bridges and other high-value concrete structures. These studies include conceptual designs, modeling, experimental verifications, and image reconstruction of simulated radar data. (3) We are exploring the efficiency of pulsed plasma processing techniques used for the removal of NO{sub x} from various effluent sources. (4) We have finished the investigation of the properties of a magnetically delayed low-pressure gas switch, which was designed here at LLNL. (5) We are applying statistical electromagnetic theory techniques to help assess microwave effects on electronic subsystems, by using a mode stirred chamber as our measurement tool. (6) We are investigating the generation of perfluoroisobutylene (PFIB) in proposed CFC replacement fluids when they are subjected to high electrical stresses and breakdown environments.

Freytag, E.K.

1993-03-01

426

Microwave Sterilization in School Microbiology.  

ERIC Educational Resources Information Center

Described are two investigations carried out in a high school biology department using a domestic microwave oven to compare the relative attributes of the autoclave and microwave oven in school use. Discussed are equipment, methods, and results of each investigation. (Author/CW)

Wynn, Brian; Dixon, Angela

1988-01-01

427

Microwave Effect on Clay Pillaring  

Microsoft Academic Search

Pillared clays may be prepared in presence of microwave irradiation as it has been extensively used in organic chemistry syntheses. Preparation time of the conventional intercalating solution takes about 2 days, but only 15 min when the preparation mixture is microwave-irradiated. The amount of water required to disperse and to dilute the pillar precursor salts is also significantly reduced. In

Geolar Fetter; Pedro Bosch

2010-01-01

428

Microwave Drying Kinetics of Okra  

Microsoft Academic Search

In this work, the effects of power level and sample mass on moisture content, moisture ratio, drying rate, and drying time of Turkey okra (Hibiscus esculenta L.) were investigated using microwave drying technique. Various microwave power levels ranging from to 180 to 900 W were used for drying of 100 g of okra. To investigate the effect of sample mass on drying,

Gökçe Dadal?; Dilek K?l?ç Apar; Belma Özbek

2007-01-01

429

CHEMICAL SYNTHESIS & TRANSFORMATIONS USING MICROWAVES  

EPA Science Inventory

A historical account of the utility of microwaves in a variety of chemical synthesis applications will be presented, including a solvent-free strategy that involves microwave (MW) exposure of neat reactants (undiluted) catalyzed by the surfaces of recyclable mineral supports such...

430