Sample records for absolute flux measurements

  1. Absolute photon-flux measurements in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Haddad, G. N.

    1974-01-01

    Absolute photon-flux measurements in the vacuum ultraviolet have extended to short wavelengths by use of rare-gas ionization chambers. The technique involves the measurement of the ion current as a function of the gas pressure in the ion chamber. The true value of the ion current, and hence the absolute photon flux, is obtained by extrapolating the ion current to zero gas pressure. Examples are given at 162 and 266 A. The short-wavelength limit is determined only by the sensitivity of the current-measuring apparatus and by present knowledge of the photoionization processes that occur in the rate gases.

  2. Absolute measurement of the extreme UV solar flux

    NASA Technical Reports Server (NTRS)

    Carlson, R. W.; Ogawa, H. S.; Judge, D. L.; Phillips, E.

    1984-01-01

    A windowless rare-gas ionization chamber has been developed to measure the absolute value of the solar extreme UV flux in the 50-575-A region. Successful results were obtained on a solar-pointing sounding rocket. The ionization chamber, operated in total absorption, is an inherently stable absolute detector of ionizing UV radiation and was designed to be independent of effects from secondary ionization and gas effusion. The net error of the measurement is + or - 7.3 percent, which is primarily due to residual outgassing in the instrument, other errors such as multiple ionization, photoelectron collection, and extrapolation to the zero atmospheric optical depth being small in comparison. For the day of the flight, Aug. 10, 1982, the solar irradiance (50-575 A), normalized to unit solar distance, was found to be 5.71 + or - 0.42 x 10 to the 10th photons per sq cm sec.

  3. Absolute flux measurements for swift atoms

    NASA Technical Reports Server (NTRS)

    Fink, M.; Kohl, D. A.; Keto, J. W.; Antoniewicz, P.

    1987-01-01

    While a torsion balance in vacuum can easily measure the momentum transfer from a gas beam impinging on a surface attached to the balance, this measurement depends on the accommodation coefficients of the atoms with the surface and the distribution of the recoil. A torsion balance is described for making absolute flux measurements independent of recoil effects. The torsion balance is a conventional taut suspension wire design and the Young modulus of the wire determines the relationship between the displacement and the applied torque. A compensating magnetic field is applied to maintain zero displacement and provide critical damping. The unique feature is to couple the impinging gas beam to the torsion balance via a Wood's horn, i.e., a thin wall tube with a gradual 90 deg bend. Just as light is trapped in a Wood's horn by specular reflection from the curved surfaces, the gas beam diffuses through the tube. Instead of trapping the beam, the end of the tube is open so that the atoms exit the tube at 90 deg to their original direction. Therefore, all of the forward momentum of the gas beam is transferred to the torsion balance independent of the angle of reflection from the surfaces inside the tube.

  4. A Measurement of the Absolute Reactor Antineutrino Flux and Spectrum at Daya Bay

    NASA Astrophysics Data System (ADS)

    An, Fengpeng

    2017-12-01

    The Daya Bay Reactor Neutrino Experiment uses an array of eight underground detectors to study antineutrinos from six reactor cores with different baselines. Since the start of data-taking from late 2011, Daya Bay has collected the largest sample of reactor antineutrino events to date, and has made the most precise measurement of the neutrino oscillation parameters sin22θ13 and Δm2ee. Using the data from the four detectors in the near experimental halls, Daya Bay has made a high statistics measurement of the absolute reactor antineutrino flux and spectrum. In this paper we will present this measurement and its comparison to predictions based on different flux models.

  5. From Hubble's NGSL to Absolute Fluxes

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Lindler, Don

    2012-01-01

    Hubble's Next Generation Spectral Library (NGSL) consists of R-l000 spectra of 374 stars of assorted temperature, gravity, and metallicity. Each spectrum covers the wavelength range, 0.18-1.00 microns. The library can be viewed and/or downloaded from the website, http://archive.stsci.edu/prepds/stisngsll. Stars in the NGSL are now being used as absolute flux standards at ground-based observatories. However, the uncertainty in the absolute flux is about 2%, which does not meet the requirements of dark-energy surveys. We are therefore developing an observing procedure that should yield fluxes with uncertainties less than 1 % and will take part in an HST proposal to observe up to 15 stars using this new procedure.

  6. High heat flux measurements and experimental calibrations/characterizations

    NASA Technical Reports Server (NTRS)

    Kidd, Carl T.

    1992-01-01

    Recent progress in techniques employed in the measurement of very high heat-transfer rates in reentry-type facilities at the Arnold Engineering Development Center (AEDC) is described. These advances include thermal analyses applied to transducer concepts used to make these measurements; improved heat-flux sensor fabrication methods, equipment, and procedures for determining the experimental time response of individual sensors; performance of absolute heat-flux calibrations at levels above 2,000 Btu/cu ft-sec (2.27 kW/cu cm); and innovative methods of performing in-situ run-to-run characterizations of heat-flux probes installed in the test facility. Graphical illustrations of the results of extensive thermal analyses of the null-point calorimeter and coaxial surface thermocouple concepts with application to measurements in aerothermal test environments are presented. Results of time response experiments and absolute calibrations of null-point calorimeters and coaxial thermocouples performed in the laboratory at intermediate to high heat-flux levels are shown. Typical AEDC high-enthalpy arc heater heat-flux data recently obtained with a Calspan-fabricated null-point probe model are included.

  7. Development of a vector-tensor system to measure the absolute magnetic flux density and its gradient in magnetically shielded rooms.

    PubMed

    Voigt, J; Knappe-Grüneberg, S; Gutkelch, D; Haueisen, J; Neuber, S; Schnabel, A; Burghoff, M

    2015-05-01

    Several experiments in fundamental physics demand an environment of very low, homogeneous, and stable magnetic fields. For the magnetic characterization of such environments, we present a portable SQUID system that measures the absolute magnetic flux density vector and the gradient tensor. This vector-tensor system contains 13 integrated low-critical temperature (LTc) superconducting quantum interference devices (SQUIDs) inside a small cylindrical liquid helium Dewar with a height of 31 cm and 37 cm in diameter. The achievable resolution depends on the flux density of the field under investigation and its temporal drift. Inside a seven-layer mu-metal shield, an accuracy better than ±23 pT for the components of the static magnetic field vector and ±2 pT/cm for each of the nine components of the gradient tensor is reached by using the shifting method.

  8. Development of a vector-tensor system to measure the absolute magnetic flux density and its gradient in magnetically shielded rooms

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Voigt, J.; Knappe-Grüneberg, S.; Gutkelch, D.

    2015-05-15

    Several experiments in fundamental physics demand an environment of very low, homogeneous, and stable magnetic fields. For the magnetic characterization of such environments, we present a portable SQUID system that measures the absolute magnetic flux density vector and the gradient tensor. This vector-tensor system contains 13 integrated low-critical temperature (LTc) superconducting quantum interference devices (SQUIDs) inside a small cylindrical liquid helium Dewar with a height of 31 cm and 37 cm in diameter. The achievable resolution depends on the flux density of the field under investigation and its temporal drift. Inside a seven-layer mu-metal shield, an accuracy better than ±23more » pT for the components of the static magnetic field vector and ±2 pT/cm for each of the nine components of the gradient tensor is reached by using the shifting method.« less

  9. Absolute flux density calibrations of radio sources: 2.3 GHz

    NASA Technical Reports Server (NTRS)

    Freiley, A. J.; Batelaan, P. D.; Bathker, D. A.

    1977-01-01

    A detailed description of a NASA/JPL Deep Space Network program to improve S-band gain calibrations of large aperture antennas is reported. The program is considered unique in at least three ways; first, absolute gain calibrations of high quality suppressed-sidelobe dual mode horns first provide a high accuracy foundation to the foundation to the program. Second, a very careful transfer calibration technique using an artificial far-field coherent-wave source was used to accurately obtain the gain of one large (26 m) aperture. Third, using the calibrated large aperture directly, the absolute flux density of five selected galactic and extragalactic natural radio sources was determined with an absolute accuracy better than 2 percent, now quoted at the familiar 1 sigma confidence level. The follow-on considerations to apply these results to an operational network of ground antennas are discussed. It is concluded that absolute gain accuracies within + or - 0.30 to 0.40 db are possible, depending primarily on the repeatability (scatter) in the field data from Deep Space Network user stations.

  10. Strategy for the absolute neutron emission measurement on ITER.

    PubMed

    Sasao, M; Bertalot, L; Ishikawa, M; Popovichev, S

    2010-10-01

    Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement subsystem, cross calibration among them, and in situ calibration are needed. Neutron transport calculation shows the suitable calibration source is a DT/DD neutron generator of source strength higher than 10(10) n/s (neutron/second) for DT and 10(8) n/s for DD. It will take eight weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.

  11. Validation of absolute axial neutron flux distribution calculations with MCNP with 197Au(n,γ)198Au reaction rate distribution measurements at the JSI TRIGA Mark II reactor.

    PubMed

    Radulović, Vladimir; Štancar, Žiga; Snoj, Luka; Trkov, Andrej

    2014-02-01

    The calculation of axial neutron flux distributions with the MCNP code at the JSI TRIGA Mark II reactor has been validated with experimental measurements of the (197)Au(n,γ)(198)Au reaction rate. The calculated absolute reaction rate values, scaled according to the reactor power and corrected for the flux redistribution effect, are in good agreement with the experimental results. The effect of different cross-section libraries on the calculations has been investigated and shown to be minor. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Antiproton Flux, Antiproton-to-Proton Flux Ratio, and Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station

    NASA Astrophysics Data System (ADS)

    Aguilar, M.; Ali Cavasonza, L.; Alpat, B.; Ambrosi, G.; Arruda, L.; Attig, N.; Aupetit, S.; Azzarello, P.; Bachlechner, A.; Barao, F.; Barrau, A.; Barrin, L.; Bartoloni, A.; Basara, L.; Başeǧmez-du Pree, S.; Battarbee, M.; Battiston, R.; Bazo, J.; Becker, U.; Behlmann, M.; Beischer, B.; Berdugo, J.; Bertucci, B.; Bindi, V.; Boella, G.; de Boer, W.; Bollweg, K.; Bonnivard, V.; Borgia, B.; Boschini, M. J.; Bourquin, M.; Bueno, E. F.; Burger, J.; Cadoux, F.; Cai, X. D.; Capell, M.; Caroff, S.; Casaus, J.; Castellini, G.; Cernuda, I.; Cervelli, F.; Chae, M. J.; Chang, Y. H.; Chen, A. I.; Chen, G. M.; Chen, H. S.; Cheng, L.; Chou, H. Y.; Choumilov, E.; Choutko, V.; Chung, C. H.; Clark, C.; Clavero, R.; Coignet, G.; Consolandi, C.; Contin, A.; Corti, C.; Coste, B.; Creus, W.; Crispoltoni, M.; Cui, Z.; Dai, Y. M.; Delgado, C.; Della Torre, S.; Demirköz, M. B.; Derome, L.; Di Falco, S.; Dimiccoli, F.; Díaz, C.; von Doetinchem, P.; Dong, F.; Donnini, F.; Duranti, M.; D'Urso, D.; Egorov, A.; Eline, A.; Eronen, T.; Feng, J.; Fiandrini, E.; Finch, E.; Fisher, P.; Formato, V.; Galaktionov, Y.; Gallucci, G.; García, B.; García-López, R. J.; Gargiulo, C.; Gast, H.; Gebauer, I.; Gervasi, M.; Ghelfi, A.; Giovacchini, F.; Goglov, P.; Gómez-Coral, D. M.; Gong, J.; Goy, C.; Grabski, V.; Grandi, D.; Graziani, M.; Guerri, I.; Guo, K. H.; Habiby, M.; Haino, S.; Han, K. C.; He, Z. H.; Heil, M.; Hoffman, J.; Hsieh, T. H.; Huang, H.; Huang, Z. C.; Huh, C.; Incagli, M.; Ionica, M.; Jang, W. Y.; Jinchi, H.; Kang, S. C.; Kanishev, K.; Kim, G. N.; Kim, K. S.; Kirn, Th.; Konak, C.; Kounina, O.; Kounine, A.; Koutsenko, V.; Krafczyk, M. S.; La Vacca, G.; Laudi, E.; Laurenti, G.; Lazzizzera, I.; Lebedev, A.; Lee, H. T.; Lee, S. C.; Leluc, C.; Li, H. S.; Li, J. Q.; Li, J. Q.; Li, Q.; Li, T. X.; Li, W.; Li, Z. H.; Li, Z. Y.; Lim, S.; Lin, C. H.; Lipari, P.; Lippert, T.; Liu, D.; Liu, Hu; Lu, S. Q.; Lu, Y. S.; Luebelsmeyer, K.; Luo, F.; Luo, J. Z.; Lv, S. S.; Majka, R.; Mañá, C.; Marín, J.; Martin, T.; Martínez, G.; Masi, N.; Maurin, D.; Menchaca-Rocha, A.; Meng, Q.; Mo, D. C.; Morescalchi, L.; Mott, P.; Nelson, T.; Ni, J. Q.; Nikonov, N.; Nozzoli, F.; Nunes, P.; Oliva, A.; Orcinha, M.; Palmonari, F.; Palomares, C.; Paniccia, M.; Pauluzzi, M.; Pensotti, S.; Pereira, R.; Picot-Clemente, N.; Pilo, F.; Pizzolotto, C.; Plyaskin, V.; Pohl, M.; Poireau, V.; Putze, A.; Quadrani, L.; Qi, X. M.; Qin, X.; Qu, Z. Y.; Räihä, T.; Rancoita, P. G.; Rapin, D.; Ricol, J. S.; Rodríguez, I.; Rosier-Lees, S.; Rozhkov, A.; Rozza, D.; Sagdeev, R.; Sandweiss, J.; Saouter, P.; Schael, S.; Schmidt, S. M.; Schulz von Dratzig, A.; Schwering, G.; Seo, E. S.; Shan, B. S.; Shi, J. Y.; Siedenburg, T.; Son, D.; Song, J. W.; Sun, W. H.; Tacconi, M.; Tang, X. W.; Tang, Z. C.; Tao, L.; Tescaro, D.; Ting, Samuel C. C.; Ting, S. M.; Tomassetti, N.; Torsti, J.; Türkoǧlu, C.; Urban, T.; Vagelli, V.; Valente, E.; Vannini, C.; Valtonen, E.; Vázquez Acosta, M.; Vecchi, M.; Velasco, M.; Vialle, J. P.; Vitale, V.; Vitillo, S.; Wang, L. Q.; Wang, N. H.; Wang, Q. L.; Wang, X.; Wang, X. Q.; Wang, Z. X.; Wei, C. C.; Weng, Z. L.; Whitman, K.; Wienkenhöver, J.; Willenbrock, M.; Wu, H.; Wu, X.; Xia, X.; Xiong, R. Q.; Xu, W.; Yan, Q.; Yang, J.; Yang, M.; Yang, Y.; Yi, H.; Yu, Y. J.; Yu, Z. Q.; Zeissler, S.; Zhang, C.; Zhang, J.; Zhang, J. H.; Zhang, S. D.; Zhang, S. W.; Zhang, Z.; Zheng, Z. M.; Zhu, Z. Q.; Zhuang, H. L.; Zhukov, V.; Zichichi, A.; Zimmermann, N.; Zuccon, P.; AMS Collaboration

    2016-08-01

    A precision measurement by AMS of the antiproton flux and the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV is presented based on 3.49 ×1 05 antiproton events and 2.42 ×1 09 proton events. The fluxes and flux ratios of charged elementary particles in cosmic rays are also presented. In the absolute rigidity range ˜60 to ˜500 GV , the antiproton p ¯, proton p , and positron e+ fluxes are found to have nearly identical rigidity dependence and the electron e- flux exhibits a different rigidity dependence. Below 60 GV, the (p ¯/p ), (p ¯/e+), and (p /e+) flux ratios each reaches a maximum. From ˜60 to ˜500 GV , the (p ¯/p ), (p ¯/e+), and (p /e+) flux ratios show no rigidity dependence. These are new observations of the properties of elementary particles in the cosmos.

  13. Antiproton Flux, Antiproton-to-Proton Flux Ratio, and Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station.

    PubMed

    Aguilar, M; Ali Cavasonza, L; Alpat, B; Ambrosi, G; Arruda, L; Attig, N; Aupetit, S; Azzarello, P; Bachlechner, A; Barao, F; Barrau, A; Barrin, L; Bartoloni, A; Basara, L; Başeǧmez-du Pree, S; Battarbee, M; Battiston, R; Bazo, J; Becker, U; Behlmann, M; Beischer, B; Berdugo, J; Bertucci, B; Bindi, V; Boella, G; de Boer, W; Bollweg, K; Bonnivard, V; Borgia, B; Boschini, M J; Bourquin, M; Bueno, E F; Burger, J; Cadoux, F; Cai, X D; Capell, M; Caroff, S; Casaus, J; Castellini, G; Cernuda, I; Cervelli, F; Chae, M J; Chang, Y H; Chen, A I; Chen, G M; Chen, H S; Cheng, L; Chou, H Y; Choumilov, E; Choutko, V; Chung, C H; Clark, C; Clavero, R; Coignet, G; Consolandi, C; Contin, A; Corti, C; Coste, B; Creus, W; Crispoltoni, M; Cui, Z; Dai, Y M; Delgado, C; Della Torre, S; Demirköz, M B; Derome, L; Di Falco, S; Dimiccoli, F; Díaz, C; von Doetinchem, P; Dong, F; Donnini, F; Duranti, M; D'Urso, D; Egorov, A; Eline, A; Eronen, T; Feng, J; Fiandrini, E; Finch, E; Fisher, P; Formato, V; Galaktionov, Y; Gallucci, G; García, B; García-López, R J; Gargiulo, C; Gast, H; Gebauer, I; Gervasi, M; Ghelfi, A; Giovacchini, F; Goglov, P; Gómez-Coral, D M; Gong, J; Goy, C; Grabski, V; Grandi, D; Graziani, M; Guerri, I; Guo, K H; Habiby, M; Haino, S; Han, K C; He, Z H; Heil, M; Hoffman, J; Hsieh, T H; Huang, H; Huang, Z C; Huh, C; Incagli, M; Ionica, M; Jang, W Y; Jinchi, H; Kang, S C; Kanishev, K; Kim, G N; Kim, K S; Kirn, Th; Konak, C; Kounina, O; Kounine, A; Koutsenko, V; Krafczyk, M S; La Vacca, G; Laudi, E; Laurenti, G; Lazzizzera, I; Lebedev, A; Lee, H T; Lee, S C; Leluc, C; Li, H S; Li, J Q; Li, J Q; Li, Q; Li, T X; Li, W; Li, Z H; Li, Z Y; Lim, S; Lin, C H; Lipari, P; Lippert, T; Liu, D; Liu, Hu; Lu, S Q; Lu, Y S; Luebelsmeyer, K; Luo, F; Luo, J Z; Lv, S S; Majka, R; Mañá, C; Marín, J; Martin, T; Martínez, G; Masi, N; Maurin, D; Menchaca-Rocha, A; Meng, Q; Mo, D C; Morescalchi, L; Mott, P; Nelson, T; Ni, J Q; Nikonov, N; Nozzoli, F; Nunes, P; Oliva, A; Orcinha, M; Palmonari, F; Palomares, C; Paniccia, M; Pauluzzi, M; Pensotti, S; Pereira, R; Picot-Clemente, N; Pilo, F; Pizzolotto, C; Plyaskin, V; Pohl, M; Poireau, V; Putze, A; Quadrani, L; Qi, X M; Qin, X; Qu, Z Y; Räihä, T; Rancoita, P G; Rapin, D; Ricol, J S; Rodríguez, I; Rosier-Lees, S; Rozhkov, A; Rozza, D; Sagdeev, R; Sandweiss, J; Saouter, P; Schael, S; Schmidt, S M; Schulz von Dratzig, A; Schwering, G; Seo, E S; Shan, B S; Shi, J Y; Siedenburg, T; Son, D; Song, J W; Sun, W H; Tacconi, M; Tang, X W; Tang, Z C; Tao, L; Tescaro, D; Ting, Samuel C C; Ting, S M; Tomassetti, N; Torsti, J; Türkoğlu, C; Urban, T; Vagelli, V; Valente, E; Vannini, C; Valtonen, E; Vázquez Acosta, M; Vecchi, M; Velasco, M; Vialle, J P; Vitale, V; Vitillo, S; Wang, L Q; Wang, N H; Wang, Q L; Wang, X; Wang, X Q; Wang, Z X; Wei, C C; Weng, Z L; Whitman, K; Wienkenhöver, J; Willenbrock, M; Wu, H; Wu, X; Xia, X; Xiong, R Q; Xu, W; Yan, Q; Yang, J; Yang, M; Yang, Y; Yi, H; Yu, Y J; Yu, Z Q; Zeissler, S; Zhang, C; Zhang, J; Zhang, J H; Zhang, S D; Zhang, S W; Zhang, Z; Zheng, Z M; Zhu, Z Q; Zhuang, H L; Zhukov, V; Zichichi, A; Zimmermann, N; Zuccon, P

    2016-08-26

    A precision measurement by AMS of the antiproton flux and the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV is presented based on 3.49×10^{5} antiproton events and 2.42×10^{9} proton events. The fluxes and flux ratios of charged elementary particles in cosmic rays are also presented. In the absolute rigidity range ∼60 to ∼500  GV, the antiproton p[over ¯], proton p, and positron e^{+} fluxes are found to have nearly identical rigidity dependence and the electron e^{-} flux exhibits a different rigidity dependence. Below 60 GV, the (p[over ¯]/p), (p[over ¯]/e^{+}), and (p/e^{+}) flux ratios each reaches a maximum. From ∼60 to ∼500  GV, the (p[over ¯]/p), (p[over ¯]/e^{+}), and (p/e^{+}) flux ratios show no rigidity dependence. These are new observations of the properties of elementary particles in the cosmos.

  14. Flux trapping in multi-loop SQUIDs and its impact on SQUID-based absolute magnetometry

    NASA Astrophysics Data System (ADS)

    Schönau, T.; Zakosarenko, V.; Schmelz, M.; Anders, S.; Meyer, H.-G.; Stolz, R.

    2018-07-01

    The effect of flux trapping on the flux-voltage characteristics of multi-loop SQUID magnetometers was investigated by means of repeated cool-down cycles in a stepwise increased magnetic background field. For a SQUID with N parallel loops, N different flux offsets, each separated by {{{Φ }}}0/N, were observed even in zero magnetic field. These flux offsets further split into a so called fine structure, which can be explained by minor asymmetries in the SQUID design. The observed results are discussed with particular regard to their impact on the previously presented absolute SQUID cascade vector magnetometer.

  15. A rare gas optics-free absolute photon flux and energy analyzer to provide absolute photoionization rates of inflowing interstellar neutrals

    NASA Technical Reports Server (NTRS)

    Judge, Darrell L.

    1994-01-01

    A prototype spectrometer has been developed for space applications requiring long term absolute EUV photon flux measurements. The energy spectrum of the incoming photons is transformed directly into an electron energy spectrum by taking advantage of the photoelectric effect in one of several rare gases at low pressures. Using an electron energy spectrometer, followed by an electron multiplier detector, pulses due to individual electrons are counted. The overall efficiency of this process can be made essentially independent of gain drifts in the signal path, and the secular degradation of optical components which is often a problem in other techniques is avoided. A very important feature of this approach is its freedom from the problem of overlapping spectral orders that plagues grating EUV spectrometers. An instrument with these features has not been flown before, but is essential to further advances in our understanding of solar EUV flux dynamics, and the coupled dynamics of terrestrial and planetary atmospheres. The detailed characteristics of this optics-free spectrometer are presented in the publications section.

  16. Measurement of neutrino flux from neutrino-electron elastic scattering

    NASA Astrophysics Data System (ADS)

    Park, J.; Aliaga, L.; Altinok, O.; Bellantoni, L.; Bercellie, A.; Betancourt, M.; Bodek, A.; Bravar, A.; Budd, H.; Cai, T.; Carneiro, M. F.; Christy, M. E.; Chvojka, J.; da Motta, H.; Dytman, S. A.; Díaz, G. A.; Eberly, B.; Felix, J.; Fields, L.; Fine, R.; Gago, A. M.; Galindo, R.; Ghosh, A.; Golan, T.; Gran, R.; Harris, D. A.; Higuera, A.; Kleykamp, J.; Kordosky, M.; Le, T.; Maher, E.; Manly, S.; Mann, W. A.; Marshall, C. M.; Martinez Caicedo, D. A.; McFarland, K. S.; McGivern, C. L.; McGowan, A. M.; Messerly, B.; Miller, J.; Mislivec, A.; Morfín, J. G.; Mousseau, J.; Naples, D.; Nelson, J. K.; Norrick, A.; Nuruzzaman; Osta, J.; Paolone, V.; Patrick, C. E.; Perdue, G. N.; Rakotondravohitra, L.; Ramirez, M. A.; Ray, H.; Ren, L.; Rimal, D.; Rodrigues, P. A.; Ruterbories, D.; Schellman, H.; Solano Salinas, C. J.; Tagg, N.; Tice, B. G.; Valencia, E.; Walton, T.; Wolcott, J.; Wospakrik, M.; Zavala, G.; Zhang, D.; Miner ν A Collaboration

    2016-06-01

    Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently a measurement of this process in an accelerator-based νμ beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ˜10 % due to uncertainties in hadron production and focusing. We have isolated a sample of 135 ±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI νμ flux from 9% to 6%. Our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies.

  17. Absolute Flux Calibration of the IRAC Instrument on the Spitzer Space Telescope Using Hubble Space Telescope Flux Standards

    NASA Astrophysics Data System (ADS)

    Bohlin, R. C.; Gordon, K. D.; Rieke, G. H.; Ardila, D.; Carey, S.; Deustua, S.; Engelbracht, C.; Ferguson, H. C.; Flanagan, K.; Kalirai, J.; Meixner, M.; Noriega-Crespo, A.; Su, K. Y. L.; Tremblay, P.-E.

    2011-05-01

    The absolute flux calibration of the James Webb Space Telescope (JWST) will be based on a set of stars observed by the Hubble and Spitzer Space Telescopes. In order to cross-calibrate the two facilities, several A, G, and white dwarf stars are observed with both Spitzer and Hubble and are the prototypes for a set of JWST calibration standards. The flux calibration constants for the four Spitzer IRAC bands 1-4 are derived from these stars and are 2.3%, 1.9%, 2.0%, and 0.5% lower than the official cold-mission IRAC calibration of Reach et al., i.e., in agreement within their estimated errors of ~2%. The causes of these differences lie primarily in the IRAC data reduction and secondarily in the spectral energy distributions of our standard stars. The independent IRAC 8 μm band-4 fluxes of Rieke et al. are about 1.5% ± 2% higher than those of Reach et al. and are also in agreement with our 8 μm result.

  18. Numerical evaluation of magnetic absolute measurements with arbitrarily distributed DI-fluxgate theodolite orientations

    NASA Astrophysics Data System (ADS)

    Brunke, Heinz-Peter; Matzka, Jürgen

    2018-01-01

    At geomagnetic observatories the absolute measurements are needed to determine the calibration parameters of the continuously recording vector magnetometer (variometer). Absolute measurements are indispensable for determining the vector of the geomagnetic field over long periods of time. A standard DI (declination, inclination) measuring scheme for absolute measurements establishes routines in magnetic observatories. The traditional measuring schema uses a fixed number of eight orientations (Jankowski et al., 1996).

    We present a numerical method, allowing for the evaluation of an arbitrary number (minimum of five as there are five independent parameters) of telescope orientations. Our method provides D, I and Z base values and calculated error bars of them.

    A general approach has significant advantages. Additional measurements may be seamlessly incorporated for higher accuracy. Individual erroneous readings are identified and can be discarded without invalidating the entire data set. A priori information can be incorporated. We expect the general method to also ease requirements for automated DI-flux measurements. The method can reveal certain properties of the DI theodolite which are not captured by the conventional method.

    Based on the alternative evaluation method, a new faster and less error-prone measuring schema is presented. It avoids needing to calculate the magnetic meridian prior to the inclination measurements.

    Measurements in the vicinity of the magnetic equator are possible with theodolites and without a zenith ocular.

    The implementation of the method in MATLAB is available as source code at the GFZ Data Center Brunke (2017).

  19. Automatic solar image motion measurements. [electronic disk flux monitoring

    NASA Technical Reports Server (NTRS)

    Colgate, S. A.; Moore, E. P.

    1975-01-01

    The solar seeing image motion has been monitored electronically and absolutely with a 25 cm telescope at three sites along the ridge at the southern end of the Magdalena Mountains west of Socorro, New Mexico. The uncorrelated component of the variations of the optical flux from two points at opposite limbs of the solar disk was continually monitored in 3 frequencies centered at 0.3, 3 and 30 Hz. The frequency band of maximum signal centered at 3 Hz showed the average absolute value of image motion to be somewhat less than 2sec. The observer estimates of combined blurring and image motion were well correlated with electronically measured image motion, but the observer estimates gave a factor 2 larger value.

  20. Measurement of neutrino flux from neutrino-electron elastic scattering

    DOE PAGES

    Park, J.; Aliaga, L.; Altinok, O.; ...

    2016-06-10

    Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently, a measurement of this process in an accelerator-based ν μ beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ~10% due to uncertainties in hadron production and focusing. We also isolated a sample of 135±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI ν μ fluxmore » from 9% to 6%. Finally, our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies.« less

  1. Micrometeorological flux measurements of aerosol and gases above Beijing

    NASA Astrophysics Data System (ADS)

    Nemitz, Eiko; Langford, Ben; Mullinger, Neil; Cowan, Nicholas; Coyle, Mhairi; Acton, William Joe; Lee, James; Fu, Pingqing

    2017-04-01

    Air pollution is estimated to cause 1.6 million premature deaths in China every year and in the winter 2016/17 Beijing had to issue health alerts and put in place ad hoc limitations on industrial and vehicular activity. Much of this pollution is attributed to emissions from industrial processes and in particular coal combustion. By contrast, the diffuse pollutant sources within the city are less well understood. This includes, e.g., emissions from the Beijing traffic fleet, the sewage system, food preparation, solid fuel combustion in the streets and small industrial processes. Within the framework of a major UK-Chinese collaboration to study air pollution and its impact on human health in Beijing, we therefore measured fluxes of a large range of pollutants from a height of 102 m on the 325 m meteorological tower at the Institute of Atmospheric Physics. Several instruments were mounted at 102 m: fluxes of CO2 and H2O were measured with an infrared gas analyser (LiCOR 7500) and fluxes of ozone with a combination of a relative fast-response ozone analyser (ROFI) and a 2B absolute O3 instrument. Total particle number fluxes were measured with a condensation particle counter (TSI CPC 3785), and size-segregated fluxes over the size range 0.06 to 20 μm with a combination of an optical Ultrafine High Sensitivity Aerosol Spectrometer (UHSAS) and an Aerodynamic Particle Sizer Spectrometer (TSI APS3321). Ammonia (NH3) fluxes were measured for the first time above the urban environment using an Aerodyne compact quantum cascade laser (QCL). In addition, composition resolved aerosol fluxes were measured with an Aerodyne Aerosol Mass Spectrometer (HR-ToF-AMS), operated in a measurement container at the bottom of the tower, which subsampled from a 120 m long copper tube (15 mm OD). The analysis so far suggests that, due to often low wind speeds, fluxes were at times de-coupled from the surface. Fluxes normalised by CO2, a tracer for the amount of fossil fuel consumed, should be

  2. A rare gas optics-free absolute photon flux and energy analyzer for solar and planetary observations

    NASA Technical Reports Server (NTRS)

    Judge, Darrell L.

    1994-01-01

    We have developed a prototype spectrometer for space applications requiring long term absolute EUV photon flux measurements. In this recently developed spectrometer, the energy spectrum of the incoming photons is transformed directly into an electron energy spectrum by taking advantage of the photoelectric effect in one of several rare gases at low pressures. Using an electron energy spectrometer, followed by an electron multiplier detector, pulses due to individual electrons are counted. The overall efficiency of this process can be made essentially independent of gain drifts in the signal path, and the secular degradation of optical components which is often a problem in other techniques is avoided. A very important feature of this approach is its freedom from the problem of overlapping spectral orders that plagues grating EUV spectrometers. An instrument with these features has not been flown before, but is essential to further advances in our understanding of solar EUV flux dynamics, and the coupled dynamics of terrestrial and planetary atmospheres. The detailed characteristics of this optics-free spectrometer are presented in the publications section.

  3. Calibrating soil respiration measures with a dynamic flux apparatus using artificial soil media of varying porosity

    Treesearch

    John R. Butnor; Kurt H. Johnsen

    2004-01-01

    Measurement of soil respiration to quantify ecosystem carbon cyclingrequires absolute, not relative, estimates of soil CO2 efflux. We describe a novel, automated efflux apparatus that can be used to test the accuracy of chamber-based soil respiration measurements by generating known CO2 fluxes. Artificial soil is supported...

  4. Advancing Absolute Calibration for JWST and Other Applications

    NASA Astrophysics Data System (ADS)

    Rieke, George; Bohlin, Ralph; Boyajian, Tabetha; Carey, Sean; Casagrande, Luca; Deustua, Susana; Gordon, Karl; Kraemer, Kathleen; Marengo, Massimo; Schlawin, Everett; Su, Kate; Sloan, Greg; Volk, Kevin

    2017-10-01

    We propose to exploit the unique optical stability of the Spitzer telescope, along with that of IRAC, to (1) transfer the accurate absolute calibration obtained with MSX on very bright stars directly to two reference stars within the dynamic range of the JWST imagers (and of other modern instrumentation); (2) establish a second accurate absolute calibration based on the absolutely calibrated spectrum of the sun, transferred onto the astronomical system via alpha Cen A; and (3) provide accurate infrared measurements for the 11 (of 15) highest priority stars with no such data but with accurate interferometrically measured diameters, allowing us to optimize determinations of effective temperatures using the infrared flux method and thus to extend the accurate absolute calibration spectrally. This program is integral to plans for an accurate absolute calibration of JWST and will also provide a valuable Spitzer legacy.

  5. Absolute gravity measurements in California

    NASA Astrophysics Data System (ADS)

    Zumberge, M. A.; Sasagawa, G.; Kappus, M.

    1986-08-01

    An absolute gravity meter that determines the local gravitational acceleration by timing a freely falling mass with a laser interferometer has been constructed. The instrument has made measurements at 11 sites in California, four in Nevada, and one in France. The uncertainty in the results is typically 10 microgal. Repeated measurements have been made at several of the sites; only one shows a substantial change in gravity.

  6. Application of the space-resolving flux detector for radiation measurements from an octahedral-aperture spherical hohlraum

    NASA Astrophysics Data System (ADS)

    Xie, Xufei; Du, Huabing; Chen, Jinwen; Liu, Shenye; Li, Zhichao; Yang, Dong; Huang, Yunbao; Ren, Kuan; Hou, Lifei; Li, Sanwei; Guo, Liang; Jiang, Xiaohua; Huo, Wenyi; Chen, Yaohua; Ren, Guoli; Lan, Ke; Wang, Feng; Jiang, Shaoen; Ding, Yongkun

    2018-06-01

    Space-resolving flux detection is an important technique for the diagnostic of the radiation field within the hohlraum in inertial confinement fusion, especially for the radiation field diagnostic in the novel spherical hohlraum with octahedral six laser entrance holes (LEHs), where localized measurements are necessary for the discrimination of the radiation flux from different LEHs. A novel space-resolving flux detector (SRFD) is developed at the SG-III laser facility for the radiation flux measurement in the first campaign of the octahedral spherical hohlraum energetics experiment. The principle and configuration of the SRFD system is introduced. The radiation flux from the wall of a gas-filled octahedral spherical hohlraum is measured for the first time by placing the SRFD system at the equatorial position of the SG-III laser facility, aiming at the hohlraum wall through one of the six LEHs. The absolute radiation flux from the re-emission area on the hohlraum wall is measured, and good consistency is found between the experimental data and the calculated data from a three-dimensional view factor analysis.

  7. Measurement of the absolute v μ-CCQE cross section at the SciBooNE experiment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aunion, Jose Luis Alcaraz

    2010-07-01

    This thesis presents the measurement of the charged current quasi-elastic (CCQE) neutrino-nucleon cross section at neutrino energies around 1 GeV. This measurement has two main physical motivations. On one hand, the neutrino-nucleon interactions at few GeV is a region where existing old data are sparse and with low statistics. The current measurement populates low energy regions with higher statistics and precision than previous experiments. On the other hand, the CCQE interaction is the most useful interaction in neutrino oscillation experiments. The CCQE channel is used to measure the initial and final neutrino fluxes in order to determine the neutrino fractionmore » that disappeared. The neutrino oscillation experiments work at low neutrino energies, so precise measurement of CCQE interactions are essential for flux measurements. The main goal of this thesis is to measure the CCQE absolute neutrino cross section from the SciBooNE data. The SciBar Booster Neutrino Experiment (SciBooNE) is a neutrino and anti-neutrino scattering off experiment. The neutrino energy spectrum works at energies around 1 GeV. SciBooNE was running from June 8th 2007 to August 18th 2008. In that period, the experiment collected a total of 2.65 x 10 20 protons on target (POT). This thesis has used full data collection in neutrino mode 0.99 x 10 20 POT. A CCQE selection cut has been performed, achieving around 70% pure CCQE sample. A fit method has been exclusively developed to determine the absolute CCQE cross section, presenting results in a neutrino energy range from 0.2 to 2 GeV. The results are compatible with the NEUT predictions. The SciBooNE measurement has been compared with both Carbon (MiniBoonE) and deuterium (ANL and BNL) target experiments, showing a good agreement in both cases.« less

  8. Line identifications, line strengths, and continuum flux measurements in the ultraviolet spectrum of Arcturus

    NASA Technical Reports Server (NTRS)

    Carpenter, K. G.; Wing, R. F.; Stencel, R. E.

    1985-01-01

    The ultraviolet spectrum of Arcturus has been observed at high resolution with the IUE satellite. Line identifications, mean absolute 'continuum' flux measurements, integrated absolute emission-line fluxes, and measurements of selected absorption line strengths are presented for the 2250-2930 A region. In the 1150-2000 A region, identifications are given primarily on the basis of low-resolution spectra. Chromospheric emission lines have been identified with low-excitation species including H I, C I, C II, O I, Mg I, Mg II, Al II, Si I, Si II, S I, and Fe II; there is no evidence for lines of C IV, N V, or other species requiring high temperatures. A search for molecular absorption features in the 2500-2930 A interval has led to several tentative identifications, but only OH could be established as definitely present. Iron lines strongly dominate the identifications in the 2250-2930 A region, Fe II accounting for about 86 percent of the emission features and Fe I for 43 percent of the identified absorption features.

  9. Pulse flux measuring device

    DOEpatents

    Riggan, William C.

    1985-01-01

    A device for measuring particle flux comprises first and second photodiode detectors for receiving flux from a source and first and second outputs for producing first and second signals representing the flux incident to the detectors. The device is capable of reducing the first output signal by a portion of the second output signal, thereby enhancing the accuracy of the device. Devices in accordance with the invention may measure distinct components of flux from a single source or fluxes from several sources.

  10. Absolute Hugoniot measurements for CH foams in the 1.5-8 Mbar range

    NASA Astrophysics Data System (ADS)

    Aglitskiy, Y.; Velikovich, A. L.; Schmitt, A. J.; Karasik, M.; Serlin, V.; Weaver, J. L.; Oh, J.; Obenschain, S. P.

    2016-10-01

    We report the absolute Hugoniot measurements for dry CH foams at 10% of solid polystyrene density. The 400 μm thick, 500 μm wide planar foam slabs covered with a 10 μm solid plastic ablator were driven with 4 ns long Nike KrF laser pulses whose intensity was varied between 10 and 50 TW/cm2. The trajectories of the shock front and the ablative piston, as well as the rarefaction fan emerging after the shock breakout from the rear surface of the target were clearly observed using the side-on monochromatic x-ray imaging radiography. From these measurements the shock density compression ratio and the shock pressure are evaluated directly. The observed compression ratios varied between 4 and 8, and the corresponding shock pressures - between 1.5 and 8 Mbar. The data was simulated with the FASTRAD3D hydrocode, using standard models of inverse bremsstrahlung absorption, flux-limited thermal conduction, and multi-group radiation diffusion. The demonstrated diagnostics technique applied in a cryo experiment would make it possible to make the first absolute Hugoniot measurements for liquid deuterium or DT-wetted CH foams, which is relevant for designing the wetted-foam indirect-drive ignition targets for NIF. This work was supported by the US DOE/NNSA.

  11. (abstract) Absolute Flux Calibrations of Venus and Jupiter at 32 GHz

    NASA Technical Reports Server (NTRS)

    Gatti, Mark S.; Klein, Michael J.

    1994-01-01

    The microwave flux densities of Venus and Jupiter at 32 GHz have been measured using a calibration standard radio telescope system at the Owens Valley Radio Observatory (OVRO) during April and May of 1993. These measurements are part of a joint JPL/Caltech program to accurately calibrate a catalog of other radio sources using the two bright planets as flux standards.

  12. An absolute measure for a key currency

    NASA Astrophysics Data System (ADS)

    Oya, Shunsuke; Aihara, Kazuyuki; Hirata, Yoshito

    It is generally considered that the US dollar and the euro are the key currencies in the world and in Europe, respectively. However, there is no absolute general measure for a key currency. Here, we investigate the 24-hour periodicity of foreign exchange markets using a recurrence plot, and define an absolute measure for a key currency based on the strength of the periodicity. Moreover, we analyze the time evolution of this measure. The results show that the credibility of the US dollar has not decreased significantly since the Lehman shock, when the Lehman Brothers bankrupted and influenced the economic markets, and has increased even relatively better than that of the euro and that of the Japanese yen.

  13. Absolute Distance Measurement with the MSTAR Sensor

    NASA Technical Reports Server (NTRS)

    Lay, Oliver P.; Dubovitsky, Serge; Peters, Robert; Burger, Johan; Ahn, Seh-Won; Steier, William H.; Fetterman, Harrold R.; Chang, Yian

    2003-01-01

    The MSTAR sensor (Modulation Sideband Technology for Absolute Ranging) is a new system for measuring absolute distance, capable of resolving the integer cycle ambiguity of standard interferometers, and making it possible to measure distance with sub-nanometer accuracy. The sensor uses a single laser in conjunction with fast phase modulators and low frequency detectors. We describe the design of the system - the principle of operation, the metrology source, beamlaunching optics, and signal processing - and show results for target distances up to 1 meter. We then demonstrate how the system can be scaled to kilometer-scale distances.

  14. Hubble Space Telescope CALSPEC Flux Standards: Sirius (and Vega)

    NASA Astrophysics Data System (ADS)

    Bohlin, R. C.

    2014-06-01

    The Space Telescope Imaging Spectrograph (STIS) has measured the flux for Sirius from 0.17 to 1.01 μm on the Hubble Space Telescope (HST) White Dwarf scale. Because of the cool debris disk around Vega, Sirius is commonly recommended as the primary IR flux standard. The measured STIS flux agrees well with predictions of a special Kurucz model atmosphere, adding confidence to the modeled IR flux predictions. The IR flux agrees to 2%-3% with respect to the standard template of Cohen and to 2% with the Midcourse Space Experiment absolute flux measurements in the mid-IR. A weighted average of the independent visible and mid-IR absolute flux measures implies that the monochromatic flux at 5557.5 Å (5556 Å in air) for Sirius and Vega, respectively, is 1.35 × 10-8 and 3.44 × 10-9 erg cm-2 s-1 Å-1 with formal uncertainties of 0.5%. Contrary to previously published conclusions, the Hipparcos photometry offers no support for the variability of Vega. Pulse pileup severely affects the Hp photometry for the brightest stars.

  15. Measurement of the absolute neutron beam polarization from a supermirror polarizer and the absolute efficiency of a neutron spin rotator for the NPDGamma experiment using a polarized 3He neutron spin-filter

    NASA Astrophysics Data System (ADS)

    Musgrave, M. M.; Baeßler, S.; Balascuta, S.; Barrón-Palos, L.; Blyth, D.; Bowman, J. D.; Chupp, T. E.; Cianciolo, V.; Crawford, C.; Craycraft, K.; Fomin, N.; Fry, J.; Gericke, M.; Gillis, R. C.; Grammer, K.; Greene, G. L.; Hamblen, J.; Hayes, C.; Huffman, P.; Jiang, C.; Kucuker, S.; McCrea, M.; Mueller, P. E.; Penttilä, S. I.; Snow, W. M.; Tang, E.; Tang, Z.; Tong, X.; Wilburn, W. S.

    2018-07-01

    Accurately measuring the neutron beam polarization of a high flux, large area neutron beam is necessary for many neutron physics experiments. The Fundamental Neutron Physics Beamline (FnPB) at the Spallation Neutron Source (SNS) is a pulsed neutron beam that was polarized with a supermirror polarizer for the NPDGamma experiment. The polarized neutron beam had a flux of ∼ 109 neutrons per second per cm2 and a cross sectional area of 10 × 12 cm2. The polarization of this neutron beam and the efficiency of a RF neutron spin rotator installed downstream on this beam were measured by neutron transmission through a polarized 3He neutron spin-filter. The pulsed nature of the SNS enabled us to employ an absolute measurement technique for both quantities which does not depend on accurate knowledge of the phase space of the neutron beam or the 3He polarization in the spin filter and is therefore of interest for any experiments on slow neutron beams from pulsed neutron sources which require knowledge of the absolute value of the neutron polarization. The polarization and spin-reversal efficiency measured in this work were done for the NPDGamma experiment, which measures the parity violating γ-ray angular distribution asymmetry with respect to the neutron spin direction in the capture of polarized neutrons on protons. The experimental technique, results, systematic effects, and applications to neutron capture targets are discussed.

  16. Self-Powered Neutron Detector Qualification for Absolute On-Line In-Pile Neutron Flux Measurements in BR2

    NASA Astrophysics Data System (ADS)

    Vermeeren, L.; Wéber, M.

    2003-06-01

    A set of ten Self-Powered Neutron Detectors with Co, Rh and Ag emitters has been irradiated in several channels of the BR2 research reactor at SCK•CEN aiming at a comparison of their performance as thermal neutron flux detectors under various conditions. To allow for a correct interpretation of their signals, all detector sensitivity contributions (prompt and delayed) were calculated using a dedicated Monte Carlo model. The various contributions were also measured separately; the agreement between calculated and experimental data, including data from activation dosimetry, was excellent. Detailed neutron flux profiles were obtained from the SPND data, after correction for the finite detector lengths and for the slow response of delayed SPNDs.

  17. Measurement of absolute gravity acceleration in Firenze

    NASA Astrophysics Data System (ADS)

    de Angelis, M.; Greco, F.; Pistorio, A.; Poli, N.; Prevedelli, M.; Saccorotti, G.; Sorrentino, F.; Tino, G. M.

    2011-01-01

    This paper reports the results from the accurate measurement of the acceleration of gravity g taken at two separate premises in the Polo Scientifico of the University of Firenze (Italy). In these laboratories, two separate experiments aiming at measuring the Newtonian constant and testing the Newtonian law at short distances are in progress. Both experiments require an independent knowledge on the local value of g. The only available datum, pertaining to the italian zero-order gravity network, was taken more than 20 years ago at a distance of more than 60 km from the study site. Gravity measurements were conducted using an FG5 absolute gravimeter, and accompanied by seismic recordings for evaluating the noise condition at the site. The absolute accelerations of gravity at the two laboratories are (980 492 160.6 ± 4.0) μGal and (980 492 048.3 ± 3.0) μGal for the European Laboratory for Non-Linear Spectroscopy (LENS) and Dipartimento di Fisica e Astronomia, respectively. Other than for the two referenced experiments, the data here presented will serve as a benchmark for any future study requiring an accurate knowledge of the absolute value of the acceleration of gravity in the study region.

  18. Towards absolute laser spectroscopic CO2 isotope ratio measurements

    NASA Astrophysics Data System (ADS)

    Anyangwe Nwaboh, Javis; Werhahn, Olav; Ebert, Volker

    2017-04-01

    Knowledge of isotope composition of carbon dioxide (CO2) in the atmosphere is necessary to identify sources and sinks of this key greenhouse gas. In the last years, laser spectroscopic techniques such as cavity ring-down spectroscopy (CRDS) and tunable diode laser absorption spectroscopy (TDLAS) have been shown to perform accurate isotope ratio measurements for CO2 and other gases like water vapour (H2O) [1,2]. Typically, isotope ratios are reported in literature referring to reference materials provided by e.g. the International Atomic Energy Agency (IAEA). However, there could be some benefit if field deployable absolute isotope ratio measurement methods were developed to address issues such as exhausted reference material like the Pee Dee Belemnite (PDB) standard. Absolute isotope ratio measurements would be particularly important for situations where reference materials do not even exist. Here, we present CRDS and TDLAS-based absolute isotope ratios (13C/12C ) in atmospheric CO2. We demonstrate the capabilities of the used methods by measuring CO2 isotope ratios in gas standards. We compare our results to values reported for the isotope certified gas standards. Guide to the expression of uncertainty in measurement (GUM) compliant uncertainty budgets on the CRDS and TDLAS absolute isotope ratio measurements are presented, and traceability is addressed. We outline the current impediments in realizing high accuracy absolute isotope ratio measurements using laser spectroscopic methods, propose solutions and the way forward. Acknowledgement Parts of this work have been carried out within the European Metrology Research Programme (EMRP) ENV52 project-HIGHGAS. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. References [1] B. Kühnreich, S. Wagner, J. C. Habig,·O. Möhler, H. Saathoff, V. Ebert, Appl. Phys. B 119:177-187 (2015). [2] E. Kerstel, L. Gianfrani, Appl. Phys. B 92, 439-449 (2008).

  19. Absolute measurements of large mirrors

    NASA Astrophysics Data System (ADS)

    Su, Peng

    The ability to produce mirrors for large astronomical telescopes is limited by the accuracy of the systems used to test the surfaces of such mirrors. Typically the mirror surfaces are measured by comparing their actual shapes to a precision master, which may be created using combinations of mirrors, lenses, and holograms. The work presented here develops several optical testing techniques that do not rely on a large or expensive precision, master reference surface. In a sense these techniques provide absolute optical testing. The Giant Magellan Telescope (GMT) has been designed with a 350 m 2 collecting area provided by a 25 m diameter primary mirror made out from seven circular independent mirror segments. These segments create an equivalent f/0.7 paraboloidal primary mirror consisting of a central segment and six outer segments. Each of the outer segments is 8.4 m in diameter and has an off-axis aspheric shape departing 14.5 mm from the best-fitting sphere. Much of the work in this dissertation is motivated by the need to measure the surfaces or such large mirrors accurately, without relying on a large or expensive precision reference surface. One method for absolute testing describing in this dissertation uses multiple measurements relative to a reference surface that is located in different positions with respect to the test surface of interest. The test measurements are performed with an algorithm that is based on the maximum likelihood (ML) method. Some methodologies for measuring large flat surfaces in the 2 m diameter range and for measuring the GMT primary mirror segments were specifically developed. For example, the optical figure of a 1.6-m flat mirror was determined to 2 nm rms accuracy using multiple 1-meter sub-aperture measurements. The optical figure of the reference surface used in the 1-meter sub-aperture measurements was also determined to the 2 nm level. The optical test methodology for a 1.7-m off axis parabola was evaluated by moving several

  20. Heat flux microsensor measurements

    NASA Technical Reports Server (NTRS)

    Terrell, J. P.; Hager, J. M.; Onishi, S.; Diller, T. E.

    1992-01-01

    A thin-film heat flux sensor has been fabricated on a stainless steel substrate. The thermocouple elements of the heat flux sensor were nickel and nichrome, and the temperature resistance sensor was platinum. The completed heat flux microsensor was calibrated at the AEDC radiation facility. The gage output was linear with heat flux with no apparent temperature effect on sensitivity. The gage was used for heat flux measurements at the NASA Langley Vitiated Air Test Facility. Vitiated air was expanded to Mach 3.0 and hydrogen fuel was injected. Measurements were made on the wall of a diverging duct downstream of the injector during all stages of the hydrogen combustion tests. Because the wall and the gage were not actively cooled, the wall temperature reached over 1000 C (1900 F) during the most severe test.

  1. Absolute branching fraction measurements of exclusive D+ semileptonic decays.

    PubMed

    Huang, G S; Miller, D H; Pavlunin, V; Sanghi, B; Shipsey, I P J; Adams, G S; Chasse, M; Cravey, M; Cummings, J P; Danko, I; Napolitano, J; He, Q; Muramatsu, H; Park, C S; Park, W; Thorndike, E H; Coan, T E; Gao, Y S; Liu, F; Artuso, M; Boulahouache, C; Blusk, S; Butt, J; Dambasuren, E; Dorjkhaidav, O; Li, J; Menaa, N; Mountain, R; Nandakumar, R; Randrianarivony, K; Redjimi, R; Sia, R; Skwarnicki, T; Stone, S; Wang, J C; Zhang, K; Csorna, S E; Bonvicini, G; Cinabro, D; Dubrovin, M; Briere, R A; Chen, G P; Chen, J; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L; Adam, N E; Alexander, J P; Berkelman, K; Cassel, D G; Crede, V; Duboscq, J E; Ecklund, K M; Ehrlich, R; Fields, L; Gibbons, L; Gittelman, B; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Hsu, L; Jones, C D; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Mahlke-Krüger, H; Meyer, T O; Onyisi, P U E; Patterson, J R; Peterson, D; Phillips, E A; Pivarski, J; Riley, D; Ryd, A; Sadoff, A J; Schwarthoff, H; Shi, X; Shepherd, M R; Stroiney, S; Sun, W M; Urner, D; Weaver, K M; Wilksen, T; Weinberger, M; Athar, S B; Avery, P; Breva-Newell, L; Patel, R; Potlia, V; Stoeck, H; Yelton, J; Rubin, P; Cawlfield, C; Eisenstein, B I; Gollin, G D; Karliner, I; Kim, D; Lowrey, N; Naik, P; Sedlack, C; Selen, M; Williams, J; Wiss, J; Edwards, K W; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Gong, D T; Hietala, J; Kubota, Y; Klein, T; Lang, B W; Li, S Z; Poling, R; Scott, A W; Smith, A; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Zweber, P; Ernst, J; Mahmood, A H; Severini, H; Asner, D M; Dytman, S A; Love, W; Mehrabyan, S; Mueller, J A; Savinov, V; Li, Z; Lopez, A; Mendez, H; Ramirez, J

    2005-10-28

    Using data collected at the psi(3770) resonance with the CLEO-c detector at the Cornell e+e- storage ring, we present improved measurements of the absolute branching fractions of D+decays to K0e+ve, pi0e+ve, K*0e+ve, and p0e+ve, and the first observation and absolute branching fraction measurement of D+ --> omega e+ve. We also report the most precise tests to date of isospin invariance in semileptonic D0 and D+ decays.

  2. NuMI Beam Flux Studies for MINERvA

    NASA Astrophysics Data System (ADS)

    Aliaga Soplin, Leonidas

    2012-03-01

    MINERνA is a few-GeV neutrino scattering experiment which is required to understand the neutrino beam flux in order to make absolute cross section measurements. We have three techniques for constraining the flux: in situ measurements, external hadron production data and muon monitors. In this presentation I will discuss the details and our progress on these efforts.

  3. An absolute photometric system at 10 and 20 microns

    NASA Technical Reports Server (NTRS)

    Rieke, G. H.; Lebofsky, M. J.; Low, F. J.

    1985-01-01

    Two new direct calibrations at 10 and 20 microns are presented in which terrestrial flux standards are referred to infrared standard stars. These measurements give both good agreement and higher accuracy when compared with previous direct calibrations. As a result, the absolute calibrations at 10 and 20 microns have now been determined with accuracies of 3 and 8 percent, respectively. A variety of absolute calibrations based on extrapolation of stellar spectra from the visible to 10 microns are reviewed. Current atmospheric models of A-type stars underestimate their fluxes by about 10 percent at 10 microns, whereas models of solar-type stars agree well with the direct calibrations. The calibration at 20 microns can probably be determined to about 5 percent by extrapolation from the more accurate result at 10 microns. The photometric system at 10 and 20 microns is updated to reflect the new absolute calibration, to base its zero point directly on the colors of A0 stars, and to improve the accuracy in the comparison of the standard stars.

  4. Absolute branching fraction measurements of exclusive D0 semileptonic decays.

    PubMed

    Coan, T E; Gao, Y S; Liu, F; Artuso, M; Boulahouache, C; Blusk, S; Butt, J; Dambasuren, E; Dorjkhaidav, O; Li, J; Menaa, N; Mountain, R; Nandakumar, R; Redjimi, R; Sia, R; Skwarnicki, T; Stone, S; Wang, J C; Zhang, K; Csorna, S E; Bonvicini, G; Cinabro, D; Dubrovin, M; Briere, R A; Chen, G P; Chen, J; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L; Adam, N E; Alexander, J P; Berkelman, K; Cassel, D G; Crede, V; Duboscq, J E; Ecklund, K M; Ehrlich, R; Fields, L; Gibbons, L; Gittelman, B; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Hsu, L; Jones, C D; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Mahlke-Krüger, H; Meyer, T O; Onyisi, P U E; Patterson, J R; Peterson, D; Pivarski, J; Phillips, E A; Riley, D; Ryd, A; Sadoff, A J; Schwarthoff, H; Shepherd, M R; Stroiney, S; Sun, W M; Urner, D; Wilksen, T; Weinberger, M; Athar, S B; Avery, P; Breva-Newell, L; Patel, R; Potlia, V; Stoeck, H; Yelton, J; Rubin, P; Cawlfield, C; Eisenstein, B I; Gollin, G D; Karliner, I; Kim, D; Lowrey, N; Naik, P; Sedlack, C; Selen, M; Williams, J; Wiss, J; Edwards, K W; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Gong, D T; Kubota, Y; Klein, T; Lang, B W; Li, S Z; Poling, R; Scott, A W; Smith, A; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Zweber, P; Ernst, J; Mahmood, A H; Severini, H; Asner, D M; Dytman, S A; Love, W; Mehrabyan, S; Mueller, J A; Savinov, V; Li, Z; Lopez, A; Mendez, H; Ramirez, J; Huang, G S; Miller, D H; Pavlunin, V; Sanghi, B; Shibata, E I; Shipsey, I P J; Adams, G S; Chasse, M; Cravey, M; Cummings, J P; Danko, I; Napolitano, J; He, Q; Muramatsu, H; Park, C S; Park, W; Thorndike, E H

    2005-10-28

    With the first data sample collected by the CLEO-c detector at the psi(3770) resonance we have studied four exclusive semileptonic decays of the D0 meson. Our results include the first observation and absolute branching fraction measurement for D0 --> p-e+ve and improved measurements of the absolute branching fractions for D0 decays to K-e+ve, pi-e+ve, and K*-e+ve.

  5. Absolute method of measuring magnetic susceptibility

    USGS Publications Warehouse

    Thorpe, A.; Senftle, F.E.

    1959-01-01

    An absolute method of standardization and measurement of the magnetic susceptibility of small samples is presented which can be applied to most techniques based on the Faraday method. The fact that the susceptibility is a function of the area under the curve of sample displacement versus distance of the magnet from the sample, offers a simple method of measuring the susceptibility without recourse to a standard sample. Typical results on a few substances are compared with reported values, and an error of less than 2% can be achieved. ?? 1959 The American Institute of Physics.

  6. 237Np absolute delayed neutron yield measurements

    NASA Astrophysics Data System (ADS)

    Doré, D.; Ledoux, X.; Nolte, R.; Gagnon-Moisan, F.; Thulliez, L.; Litaize, O.; Roettger, S.; Serot, O.

    2017-09-01

    237Np absolute delayed neutron yields have been measured at different incident neutron energies from 1.5 to 16 MeV. The experiment was performed at the Physikalisch-Technische Bundesanstalt (PTB) facility where the Van de Graaff accelerator and the cyclotron CV28 delivered 9 different neutron energy beams using p+T, d+D and d+T reactions. The detection system is made up of twelve 3He tubes inserted into a polyethylene cylinder. In this paper, the experimental setup and the data analysis method are described. The evolution of the absolute DN yields as a function of the neutron incident beam energies are presented and compared to experimental data found in the literature and data from the libraries.

  7. Spectral estimates of net radiation and soil heat flux

    USGS Publications Warehouse

    Daughtry, C.S.T.; Kustas, William P.; Moran, M.S.; Pinter, P. J.; Jackson, R. D.; Brown, P.W.; Nichols, W.D.; Gay, L.W.

    1990-01-01

    Conventional methods of measuring surface energy balance are point measurements and represent only a small area. Remote sensing offers a potential means of measuring outgoing fluxes over large areas at the spatial resolution of the sensor. The objective of this study was to estimate net radiation (Rn) and soil heat flux (G) using remotely sensed multispectral data acquired from an aircraft over large agricultural fields. Ground-based instruments measured Rn and G at nine locations along the flight lines. Incoming fluxes were also measured by ground-based instruments. Outgoing fluxes were estimated using remotely sensed data. Remote Rn, estimated as the algebraic sum of incoming and outgoing fluxes, slightly underestimated Rn measured by the ground-based net radiometers. The mean absolute errors for remote Rn minus measured Rn were less than 7%. Remote G, estimated as a function of a spectral vegetation index and remote Rn, slightly overestimated measured G; however, the mean absolute error for remote G was 13%. Some of the differences between measured and remote values of Rn and G are associated with differences in instrument designs and measurement techniques. The root mean square error for available energy (Rn - G) was 12%. Thus, methods using both ground-based and remotely sensed data can provide reliable estimates of the available energy which can be partitioned into sensible and latent heat under nonadvective conditions. ?? 1990.

  8. Measuring Fast-Temporal Sediment Fluxes with an Analogue Acoustic Sensor: A Wind Tunnel Study

    PubMed Central

    Poortinga, Ate; van Minnen, Jan; Keijsers, Joep; Riksen, Michel; Goossens, Dirk; Seeger, Manuel

    2013-01-01

    In aeolian research, field measurements are important for studying complex wind-driven processes for land management evaluation and model validation. Consequently, there have been many devices developed, tested, and applied to investigate a range of aeolian-based phenomena. However, determining the most effective application and data analysis techniques is widely debated in the literature. Here we investigate the effectiveness of two different sediment traps (the BEST trap and the MWAC catcher) in measuring vertical sediment flux. The study was performed in a wind tunnel with sediment fluxes characterized using saltiphones. Contrary to most studies, we used the analogue output of five saltiphones mounted on top of each other to determine the total kinetic energy, which was then used to calculate aeolian sediment budgets. Absolute sediment losses during the experiments were determined using a balance located beneath the test tray. Test runs were conducted with different sand sizes and at different wind speeds. The efficiency of the two traps did not vary with the wind speed or sediment size but was affected by both the experimental setup (position of the lowest trap above the surface and number of traps in the saltation layer) and the technique used to calculate the sediment flux. Despite this, good agreement was found between sediment losses calculated from the saltiphone and those measured using the balance. The results of this study provide a framework for measuring sediment fluxes at small time resolution (seconds to milliseconds) in the field. PMID:24058512

  9. Measuring fast-temporal sediment fluxes with an analogue acoustic sensor: a wind tunnel study.

    PubMed

    Poortinga, Ate; van Minnen, Jan; Keijsers, Joep; Riksen, Michel; Goossens, Dirk; Seeger, Manuel

    2013-01-01

    In aeolian research, field measurements are important for studying complex wind-driven processes for land management evaluation and model validation. Consequently, there have been many devices developed, tested, and applied to investigate a range of aeolian-based phenomena. However, determining the most effective application and data analysis techniques is widely debated in the literature. Here we investigate the effectiveness of two different sediment traps (the BEST trap and the MWAC catcher) in measuring vertical sediment flux. The study was performed in a wind tunnel with sediment fluxes characterized using saltiphones. Contrary to most studies, we used the analogue output of five saltiphones mounted on top of each other to determine the total kinetic energy, which was then used to calculate aeolian sediment budgets. Absolute sediment losses during the experiments were determined using a balance located beneath the test tray. Test runs were conducted with different sand sizes and at different wind speeds. The efficiency of the two traps did not vary with the wind speed or sediment size but was affected by both the experimental setup (position of the lowest trap above the surface and number of traps in the saltation layer) and the technique used to calculate the sediment flux. Despite this, good agreement was found between sediment losses calculated from the saltiphone and those measured using the balance. The results of this study provide a framework for measuring sediment fluxes at small time resolution (seconds to milliseconds) in the field.

  10. High-performance multi-channel fiber-based absolute distance measuring interferometer system

    NASA Astrophysics Data System (ADS)

    Deck, Leslie L.

    2009-08-01

    I describe the principle of operation and performance of a fiber-based absolute distance measuring interferometer system with 60 independent simultaneous channels. The system was designed for demanding applications requiring passive, electrically immune sensors with an extremely long MTTF. In addition to providing better than 0.3nm measurement repeatability at 5KHz for all channels, the system demonstrated absolute distance uncertainty of less than 5nm over a 500 micron measurement range.

  11. Laser interferometry method for absolute measurement of the acceleration of gravity

    NASA Technical Reports Server (NTRS)

    Hudson, O. K.

    1971-01-01

    Gravimeter permits more accurate and precise absolute measurement of g without reference to Potsdam values as absolute standards. Device is basically Michelson laser beam interferometer in which one arm is mass fitted with corner cube reflector.

  12. Measurement of absolute gamma emission probabilities

    NASA Astrophysics Data System (ADS)

    Sumithrarachchi, Chandana S.; Rengan, Krish; Griffin, Henry C.

    2003-06-01

    The energies and emission probabilities (intensities) of gamma-rays emitted in radioactive decays of particular nuclides are the most important characteristics by which to quantify mixtures of radionuclides. Often, quantification is limited by uncertainties in measured intensities. A technique was developed to reduce these uncertainties. The method involves obtaining a pure sample of a nuclide using radiochemical techniques, and using appropriate fractions for beta and gamma measurements. The beta emission rates were measured using a liquid scintillation counter, and the gamma emission rates were measured with a high-purity germanium detector. Results were combined to obtain absolute gamma emission probabilities. All sources of uncertainties greater than 0.1% were examined. The method was tested with 38Cl and 88Rb.

  13. Relating chamber measurements to eddy correlation measurements of methane flux

    Treesearch

    R.J. Clement; S.B. Verma; E.S. Verry

    1995-01-01

    Methane fluxes were measured using eddy correlation and chamber techniques during 1991 and 1997 at a peatland in north central Minnesota. Comparisons of the two techniques were made using averages of methane flux data available during 1-week periods. The seasonal patterns of fluxes measured by the two techniques compared well. Chamber flux, in 1991, was about 1.8 mg m...

  14. 242Pu absolute neutron-capture cross section measurement

    NASA Astrophysics Data System (ADS)

    Buckner, M. Q.; Wu, C. Y.; Henderson, R. A.; Bucher, B.; Chyzh, A.; Bredeweg, T. A.; Baramsai, B.; Couture, A.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Ullmann, J. L.

    2017-09-01

    The absolute neutron-capture cross section of 242Pu was measured at the Los Alamos Neutron Science Center using the Detector for Advanced Neutron-Capture Experiments array along with a compact parallel-plate avalanche counter for fission-fragment detection. During target fabrication, a small amount of 239Pu was added to the active target so that the absolute scale of the 242Pu(n,γ) cross section could be set according to the known 239Pu(n,f) resonance at En,R = 7.83 eV. The relative scale of the 242Pu(n,γ) cross section covers four orders of magnitude for incident neutron energies from thermal to ≈ 40 keV. The cross section reported in ENDF/B-VII.1 for the 242Pu(n,γ) En,R = 2.68 eV resonance was found to be 2.4% lower than the new absolute 242Pu(n,γ) cross section.

  15. Ratio measures in leading medical journals: structured review of accessibility of underlying absolute risks

    PubMed Central

    Schwartz, Lisa M; Dvorin, Evan L; Welch, H Gilbert

    2006-01-01

    Objective To examine the accessibility of absolute risk in articles reporting ratio measures in leading medical journals. Design Structured review of abstracts presenting ratio measures. Setting Articles published between 1 June 2003 and 1 May 2004 in Annals of Internal Medicine, BMJ, Journal of the American Medical Association, Journal of the National Cancer Institute, Lancet, and New England Journal of Medicine. Participants 222 articles based on study designs in which absolute risks were directly calculable (61 randomised trials, 161 cohort studies). Main outcome measure Accessibility of the absolute risks underlying the first ratio measure in the abstract. Results 68% of articles (150/222) failed to report the underlying absolute risks for the first ratio measure in the abstract (range 55−81% across the journals). Among these articles, about half did report the underlying absolute risks elsewhere in the article (text, table, or figure) but half did not report them anywhere. Absolute risks were more likely to be reported in the abstract for randomised trials compared with cohort studies (62% v 21%; relative risk 3.0, 95% confidence interval 2.1 to 4.2) and for studies reporting crude compared with adjusted ratio measures (62% v 21%; relative risk 3.0, 2.1 to 4.3). Conclusion Absolute risks are often not easily accessible in articles reporting ratio measures and sometimes are missing altogether—this lack of accessibility can easily exaggerate readers' perceptions of benefit or harm. PMID:17060338

  16. Temperature-dependent Absolute Refractive Index Measurements of Synthetic Fused Silica

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.; Frey, Bradley J.

    2006-01-01

    Using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, we have measured the absolute refractive index of five specimens taken from a very large boule of Corning 7980 fused silica from temperatures ranging from 30 to 310 K at wavelengths from 0.4 to 2.6 microns with an absolute uncertainty of plus or minus 1 x 10 (exp -5). Statistical variations in derived values of the thermo-optic coefficient (dn/dT) are at the plus or minus 2 x 10 (exp -8)/K level. Graphical and tabulated data for absolute refractive index, dispersion, and thermo-optic coefficient are presented for selected wavelengths and temperatures along with estimates of uncertainty in index. Coefficients for temperature-dependent Sellmeier fits of measured refractive index are also presented to allow accurate interpolation of index to other wavelengths and temperatures. We compare our results to those from an independent investigation (which used an interferometric technique for measuring index changes as a function of temperature) whose samples were prepared from the same slugs of material from which our prisms were prepared in support of the Kepler mission. We also compare our results with sparse cryogenic index data from measurements of this material from the literature.

  17. Absolute far-ultraviolet spectrophotometry of hot subluminous stars from Voyager

    NASA Technical Reports Server (NTRS)

    Holberg, J. B.; Ali, B.; Carone, T. E.; Polidan, R. S.

    1991-01-01

    Observations, obtained with the Voyager ultraviolet spectrometers, are presented of absolute fluxes for two well-known hot subluminous stars: BD + 28 deg 4211, an sdO, and G191 - B2B, a hot DA white dwarf. Complete absolute energy distributions for these two stars, from the Lyman limit at 912 A to 1 micron, are given. For BD + 28 deg 4211, a single power law closely represents the entire observed energy distribution. For G191 - B2B, a pure hydrogen model atmosphere provides an excellent match to the entire absolute energy distribution. Voyager absolute fluxes are discussed in relation to those reported from various sounding rocket experiments, including a recent rocket observation of BD + 28 deg 4211.

  18. Measuring surface fluxes in CAPE

    NASA Technical Reports Server (NTRS)

    Kanemasu, E. T.; D-Shah, T.; Nie, Dalin

    1992-01-01

    Two stations (site 1612 and site 2008) were operated by the University of Georgia group from 6 July 1991 to 18 August 1991. The following data were collected continuously: surface energy fluxes (i.e., net radiation, soil heat fluxes, sensible heat flux and latent heat flux), air temperature, vapor pressure, soil temperature (at 1 cm depth), and precipitation. Canopy reflectance and light interception data were taken three times at each site between 6 July and 18 August. Soil moisture content was measured twice at each site.

  19. Absolute Calibration of Si iRMs used for Measurements of Si Paleo-nutrient proxies

    NASA Astrophysics Data System (ADS)

    Vocke, R. D., Jr.; Rabb, S. A.

    2016-12-01

    Silicon isotope variations (reported as δ30Si and δ29Si, relative to NBS28) in silicic acid dissolved in ocean waters, in biogenic silica and in diatoms are extremely informative paleo-nutrient proxies. The resolution and comparability of such measurements depend on the quality of the isotopic Reference Materials (iRMs) defining the delta scale. We report new absolute Si isotopic measurements on the iRMs NBS28 (RM 8546 - Silica Sand), Diatomite, and Big Batch using the Avogadro measurement approach and comparing them with prior assessments of these iRMs. The Avogadro Si measurement technique was developed by the German Physikalish-Technische Bundesanstalt (PTB) to provide a precise and highly accurate method to measure absolute isotopic ratios in highly enriched 28Si (99.996%) material. These measurements are part of an international effort to redefine the kg and mole based on the Planck constant h and the Avogadro constant NA, respectively (Vocke et al., 2014 Metrologia 51, 361, Azuma et al., 2015 Metrologia 52 360). This approach produces absolute Si isotope ratio data with lower levels of uncertainty when compared to the traditional "Atomic Weights" method of absolute isotope ratio measurement calibration. This is illustrated in Fig. 1 where absolute Si isotopic measurements on SRM 990, separated by 40+ years of advances in instrumentation, are compared. The availability of this new technique does not say that absolute Si isotopic ratios are or ever will be better for normal Si isotopic measurements when seeking isotopic variations in nature, because they are not. However, by determining the absolute isotopic ratios of all the Si iRM scale artifacts, such iRMs become traceable to the metric system (SI); thereby automatically conferring on all the artifact-based δ30Si and δ29Si measurements traceability to the base SI unit, the mole. Such traceability should help reduce the potential of bias between different iRMs and facilitate the replacement of delta

  20. Latent Heat in Soil Heat Flux Measurements

    USDA-ARS?s Scientific Manuscript database

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

  1. Advances in the Surface Renewal Flux Measurement Method

    NASA Astrophysics Data System (ADS)

    Shapland, T. M.; McElrone, A.; Paw U, K. T.; Snyder, R. L.

    2011-12-01

    The measurement of ecosystem-scale energy and mass fluxes between the planetary surface and the atmosphere is crucial for understanding geophysical processes. Surface renewal is a flux measurement technique based on analyzing the turbulent coherent structures that interact with the surface. It is a less expensive technique because it does not require fast-response velocity measurements, but only a fast-response scalar measurement. It is therefore also a useful tool for the study of the global cycling of trace gases. Currently, surface renewal requires calibration against another flux measurement technique, such as eddy covariance, to account for the linear bias of its measurements. We present two advances in the surface renewal theory and methodology that bring the technique closer to becoming a fully independent flux measurement method. The first advance develops the theory of turbulent coherent structure transport associated with the different scales of coherent structures. A novel method was developed for identifying the scalar change rate within structures at different scales. Our results suggest that for canopies less than one meter in height, the second smallest coherent structure scale dominates the energy and mass flux process. Using the method for resolving the scalar exchange rate of the second smallest coherent structure scale, calibration is unnecessary for surface renewal measurements over short canopies. This study forms the foundation for analysis over more complex surfaces. The second advance is a sensor frequency response correction for measuring the sensible heat flux via surface renewal. Inexpensive fine-wire thermocouples are frequently used to record high frequency temperature data in the surface renewal technique. The sensible heat flux is used in conjunction with net radiation and ground heat flux measurements to determine the latent heat flux as the energy balance residual. The robust thermocouples commonly used in field experiments

  2. Dynamic frequency-domain interferometer for absolute distance measurements with high resolution

    NASA Astrophysics Data System (ADS)

    Weng, Jidong; Liu, Shenggang; Ma, Heli; Tao, Tianjiong; Wang, Xiang; Liu, Cangli; Tan, Hua

    2014-11-01

    A unique dynamic frequency-domain interferometer for absolute distance measurement has been developed recently. This paper presents the working principle of the new interferometric system, which uses a photonic crystal fiber to transmit the wide-spectrum light beams and a high-speed streak camera or frame camera to record the interference stripes. Preliminary measurements of harmonic vibrations of a speaker, driven by a radio, and the changes in the tip clearance of a rotating gear wheel show that this new type of interferometer has the ability to perform absolute distance measurements both with high time- and distance-resolution.

  3. Absolute neutrino mass measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wolf, Joachim

    2011-10-06

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments inmore » Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.« less

  4. 31P magnetization transfer measurements of Pi→ATP flux in exercising human muscle

    PubMed Central

    Savage, David B.; Williams, Guy B.; Porter, David; Carpenter, T. Adrian; Brindle, Kevin M.; Kemp, Graham J.

    2016-01-01

    Fundamental criticisms have been made over the use of 31P magnetic resonance spectroscopy (MRS) magnetization transfer estimates of inorganic phosphate (Pi)→ATP flux (VPi-ATP) in human resting skeletal muscle for assessing mitochondrial function. Although the discrepancy in the magnitude of VPi-ATP is now acknowledged, little is known about its metabolic determinants. Here we use a novel protocol to measure VPi-ATP in human exercising muscle for the first time. Steady-state VPi-ATP was measured at rest and over a range of exercise intensities and compared with suprabasal oxidative ATP synthesis rates estimated from the initial rates of postexercise phosphocreatine resynthesis (VATP). We define a surplus Pi→ATP flux as the difference between VPi-ATP and VATP. The coupled reactions catalyzed by the glycolytic enzymes GAPDH and phosphoglycerate kinase (PGK) have been shown to catalyze measurable exchange between ATP and Pi in some systems and have been suggested to be responsible for this surplus flux. Surplus VPi-ATP did not change between rest and exercise, even though the concentrations of Pi and ADP, which are substrates for GAPDH and PGK, respectively, increased as expected. However, involvement of these enzymes is suggested by correlations between absolute and surplus Pi→ATP flux, both at rest and during exercise, and the intensity of the phosphomonoester peak in the 31P NMR spectrum. This peak includes contributions from sugar phosphates in the glycolytic pathway, and changes in its intensity may indicate changes in downstream glycolytic intermediates, including 3-phosphoglycerate, which has been shown to influence the exchange between ATP and Pi catalyzed by GAPDH and PGK. PMID:26744504

  5. 31P magnetization transfer measurements of Pi→ATP flux in exercising human muscle.

    PubMed

    Sleigh, Alison; Savage, David B; Williams, Guy B; Porter, David; Carpenter, T Adrian; Brindle, Kevin M; Kemp, Graham J

    2016-03-15

    Fundamental criticisms have been made over the use of (31)P magnetic resonance spectroscopy (MRS) magnetization transfer estimates of inorganic phosphate (Pi)→ATP flux (VPi-ATP) in human resting skeletal muscle for assessing mitochondrial function. Although the discrepancy in the magnitude of VPi-ATP is now acknowledged, little is known about its metabolic determinants. Here we use a novel protocol to measure VPi-ATP in human exercising muscle for the first time. Steady-state VPi-ATP was measured at rest and over a range of exercise intensities and compared with suprabasal oxidative ATP synthesis rates estimated from the initial rates of postexercise phosphocreatine resynthesis (VATP). We define a surplus Pi→ATP flux as the difference between VPi-ATP and VATP. The coupled reactions catalyzed by the glycolytic enzymes GAPDH and phosphoglycerate kinase (PGK) have been shown to catalyze measurable exchange between ATP and Pi in some systems and have been suggested to be responsible for this surplus flux. Surplus VPi-ATP did not change between rest and exercise, even though the concentrations of Pi and ADP, which are substrates for GAPDH and PGK, respectively, increased as expected. However, involvement of these enzymes is suggested by correlations between absolute and surplus Pi→ATP flux, both at rest and during exercise, and the intensity of the phosphomonoester peak in the (31)P NMR spectrum. This peak includes contributions from sugar phosphates in the glycolytic pathway, and changes in its intensity may indicate changes in downstream glycolytic intermediates, including 3-phosphoglycerate, which has been shown to influence the exchange between ATP and Pi catalyzed by GAPDH and PGK. Copyright © 2016 the American Physiological Society.

  6. The correction of vibration in frequency scanning interferometry based absolute distance measurement system for dynamic measurements

    NASA Astrophysics Data System (ADS)

    Lu, Cheng; Liu, Guodong; Liu, Bingguo; Chen, Fengdong; Zhuang, Zhitao; Xu, Xinke; Gan, Yu

    2015-10-01

    Absolute distance measurement systems are of significant interest in the field of metrology, which could improve the manufacturing efficiency and accuracy of large assemblies in fields such as aircraft construction, automotive engineering, and the production of modern windmill blades. Frequency scanning interferometry demonstrates noticeable advantages as an absolute distance measurement system which has a high precision and doesn't depend on a cooperative target. In this paper , the influence of inevitable vibration in the frequency scanning interferometry based absolute distance measurement system is analyzed. The distance spectrum is broadened as the existence of Doppler effect caused by vibration, which will bring in a measurement error more than 103 times bigger than the changes of optical path difference. In order to decrease the influence of vibration, the changes of the optical path difference are monitored by a frequency stabilized laser, which runs parallel to the frequency scanning interferometry. The experiment has verified the effectiveness of this method.

  7. Real-time diamagnetic flux measurements on ASDEX Upgrade.

    PubMed

    Giannone, L; Geiger, B; Bilato, R; Maraschek, M; Odstrčil, T; Fischer, R; Fuchs, J C; McCarthy, P J; Mertens, V; Schuhbeck, K H

    2016-05-01

    Real-time diamagnetic flux measurements are now available on ASDEX Upgrade. In contrast to the majority of diamagnetic flux measurements on other tokamaks, no analog summation of signals is necessary for measuring the change in toroidal flux or for removing contributions arising from unwanted coupling to the plasma and poloidal field coil currents. To achieve the highest possible sensitivity, the diamagnetic measurement and compensation coil integrators are triggered shortly before plasma initiation when the toroidal field coil current is close to its maximum. In this way, the integration time can be chosen to measure only the small changes in flux due to the presence of plasma. Two identical plasma discharges with positive and negative magnetic field have shown that the alignment error with respect to the plasma current is negligible. The measured diamagnetic flux is compared to that predicted by TRANSP simulations. The poloidal beta inferred from the diamagnetic flux measurement is compared to the values calculated from magnetic equilibrium reconstruction codes. The diamagnetic flux measurement and TRANSP simulation can be used together to estimate the coupled power in discharges with dominant ion cyclotron resonance heating.

  8. Reliable absolute analog code retrieval approach for 3D measurement

    NASA Astrophysics Data System (ADS)

    Yu, Shuang; Zhang, Jing; Yu, Xiaoyang; Sun, Xiaoming; Wu, Haibin; Chen, Deyun

    2017-11-01

    The wrapped phase of phase-shifting approach can be unwrapped by using Gray code, but both the wrapped phase error and Gray code decoding error can result in period jump error, which will lead to gross measurement error. Therefore, this paper presents a reliable absolute analog code retrieval approach. The combination of unequal-period Gray code and phase shifting patterns at high frequencies are used to obtain high-frequency absolute analog code, and at low frequencies, the same unequal-period combination patterns are used to obtain the low-frequency absolute analog code. Next, the difference between the two absolute analog codes was employed to eliminate period jump errors, and a reliable unwrapped result can be obtained. Error analysis was used to determine the applicable conditions, and this approach was verified through theoretical analysis. The proposed approach was further verified experimentally. Theoretical analysis and experimental results demonstrate that the proposed approach can perform reliable analog code unwrapping.

  9. Apparatus for measuring a flux of neutrons

    DOEpatents

    Stringer, James L.

    1977-01-01

    A flux of neutrons is measured by disposing a detector in the flux and applying electronic correlation techniques to discriminate between the electrical signals generated by the neutron detector and the unwanted interfering electrical signals generated by the incidence of a neutron flux upon the cables connecting the detector to the electronic measuring equipment at a remote location.

  10. Integrated passive flux measurement in groundwater: design and performance of iFLUX samplers

    NASA Astrophysics Data System (ADS)

    Verreydt, Goedele; Razaei, Meisam; Meire, Patrick; Van Keer, Ilse; Bronders, Jan; Seuntjens, Piet

    2017-04-01

    The monitoring and management of soil and groundwater is a challenge. Current methods for the determination of movement or flux of pollution in groundwater use no direct measurements but only simulations based on concentration measurements and Darcy velocity estimations. This entails large uncertainties which cause remediation failures and higher costs for contaminated site owners. On top of that, the lack of useful data makes it difficult to get approval for a risk-based management approach which completely avoids costly remedial actions. The iFLUX technology is a key development of Dr. Goedele Verreydt at the University of Antwerp and VITO. It is supported by the passive flux measurement technology as invented by Prof. Mike Annable and his team at the University of Florida. The iFLUX technology includes an in situ measurement device for capturing dynamic groundwater quality and quantity, the iFLUX sampler, and an associated interpretation and visualization method. The iFLUX sampler is a modular passive sampler that provides simultaneous in situ point determinations of a time-averaged target compound mass flux and water flux. The sampler is typically installed in a monitoring well where it intercepts the groundwater flow and captures the compounds of interest. The sampler consists of permeable cartridges which are each packed with a specific sorbent matrix. The sorbent matrix of the water flux cartridge is impregnated with known amounts of water soluble resident tracers. These tracers are leached from the matrix at rates proportional to the groundwater flux. The measurements of the contaminants and the remaining resident tracer are used to determine groundwater and target compound fluxes. Exposure times range from 1 week to 6 months, depending on the expected concentration and groundwater flow velocity. The iFLUX sampler technology has been validated and tested at several field projects. Currently, 4 cartridges are tested and available: 1 waterflux cartridge to

  11. Improvements in absolute seismometer sensitivity calibration using local earth gravity measurements

    USGS Publications Warehouse

    Anthony, Robert E.; Ringler, Adam; Wilson, David

    2018-01-01

    The ability to determine both absolute and relative seismic amplitudes is fundamentally limited by the accuracy and precision with which scientists are able to calibrate seismometer sensitivities and characterize their response. Currently, across the Global Seismic Network (GSN), errors in midband sensitivity exceed 3% at the 95% confidence interval and are the least‐constrained response parameter in seismic recording systems. We explore a new methodology utilizing precise absolute Earth gravity measurements to determine the midband sensitivity of seismic instruments. We first determine the absolute sensitivity of Kinemetrics EpiSensor accelerometers to 0.06% at the 99% confidence interval by inverting them in a known gravity field at the Albuquerque Seismological Laboratory (ASL). After the accelerometer is calibrated, we install it in its normal configuration next to broadband seismometers and subject the sensors to identical ground motions to perform relative calibrations of the broadband sensors. Using this technique, we are able to determine the absolute midband sensitivity of the vertical components of Nanometrics Trillium Compact seismometers to within 0.11% and Streckeisen STS‐2 seismometers to within 0.14% at the 99% confidence interval. The technique enables absolute calibrations from first principles that are traceable to National Institute of Standards and Technology (NIST) measurements while providing nearly an order of magnitude more precision than step‐table calibrations.

  12. Eddy covariance measurement of isoprene fluxes

    NASA Astrophysics Data System (ADS)

    Guenther, Alex B.; Hills, Alan J.

    1998-06-01

    A system has been developed to directly measure isoprene flux above a forest canopy by eddy covariance using the combination of a fast response, real-time isoprene sensor and sonic anemometer. This system is suitable for making nearly unattended, long-term, and continuous measurements of isoprene fluxes. Isoprene detection is based on chemiluminescence between isoprene and reactant ozone, which produces green light at 500 nm. The sensor has a noise level (1σ) of 450 pptv for a 1-s integration which is dominated by random high-frequency noise that does not significantly degrade eddy covariance flux measurements. Interference from the flux of other compounds is primarily due to the emission of monoterpenes, propene, ethene, and methyl butenol and the deposition of methacrolein and methyl vinyl ketone. The average total interference for North American landscapes in midday summer is estimated to be about 5% for emissions and -3% for deposition fluxes. In only a few North American landscapes, where isoprene emissions are very low and methyl butenol emissions are high, are interferences predicted to be significant. The system was field tested on a tower above a mixed deciduous forest canopy (Duke Forest, North Carolina, U.S.A.) dominated by oak trees, which are strong isoprene emitters. Isoprene fluxes were estimated for 307 half-hour sampling periods over 10 days. Daytime fluxes ranging from 1 to 14 mg C m-2 h-1 were strongly correlated with light and temperature. The daytime mean flux of 6 mg C m-2 h-1 is similar to previous estimates determined by relaxed eddy accumulation by Geron et al [1997] at this site. Nighttime fluxes were near zero (0.01±0.03 mg C m-2 h-1).

  13. Turbulent Fogwater Flux Measurements Above A Forest

    NASA Astrophysics Data System (ADS)

    Burkard, R.; Eugster, W.; Buetzberger, P.; Siegwolf, R.

    Many forest ecosystems in elevated regions receive a significant fraction of their wa- ter and nutrient input by the interception of fogwater. Recently, several studies have demonstrated the suitability of the eddy covariance technique for the direct measure- ment of turbulent liquid water fluxes. Since summer 2001 a fogwater flux measure- ment equipment has been running at a montane site above a mixed forest canopy in Switzerland. The measurement equipment consists of a high-speed size-resolving droplet spectrometer and a three-dimensional ultrasonic anemometer. The chemical composition of the fogwater was determined from samples collected with a modified Caltech active strand collector. The deposition of nutrients by fog (occult deposition) was calculated by multiplying the total fogwater flux (total of measured turbulent and calculated gravitational flux) during each fog event by the ionic concentrations found in the collected fogwater. Several uncertainties still exist as far as the accuracy of the measurements is con- cerned. Although there is no universal statistical approach for testing the quality of the liquid water flux data directly, results of independent data quality checks of the two time series involved in the flux computation and accordingly the two instruments (ultrasonic anemometer and the droplet spectrometer) are presented. Within the measurement period, over 80 fog events with a duration longer than 2.5 hours were analyzed. An enormous physical and chemical heterogeneity among these fog events was found. We assume that some of this heterogeneity is due to the fact that fog or cloud droplets are not conservative entities: the turbulent flux of fog droplets, which can be referred to as the liquid water flux, is affected by phase change processes and coagulation. The measured coexistence of upward fluxes of small fog droplets (di- ameter < 10 µm) with the downward transport of larger droplets indicates the influ- ence of such processes. With the

  14. Impurity identifications, concentrations and particle fluxes from spectral measurements of the EXTRAP T2R plasma

    NASA Astrophysics Data System (ADS)

    Menmuir, S.; Kuldkepp, M.; Rachlew, E.

    2006-10-01

    An absolute intensity calibrated 0.5 m spectrometer with optical multi-channel analyser detector was used to observe the visible-UV radiation from the plasma in the EXTRAP T2R reversed field pinch experiment. Spectral lines were identified indicating the presence of oxygen, chromium, iron and molybdenum impurities in the hydrogen plasma. Certain regions of interest were examined in more detail and at different times in the plasma discharge. Impurity concentration calculations were made using the absolute intensities of lines of OIV and OV measured at 1-2 ms into the discharge generating estimates of the order of 0.2% of ne in the central region rising to 0.7% of ne at greater radii for OIV and 0.3% rising to 0.6% for OV. Edge electron temperatures of 0.5-5 eV at electron densities of 5-10×1011 cm-3 were calculated from the measured relative intensities of hydrogen Balmer lines. The absolute intensities of hydrogen lines and of multiplets of neutral chromium and molybdenum were used to determine particle fluxes (at 4-5 ms into the plasma) of the order 1×1016, 7×1013 and 3×1013 particles cm-2 s-1, respectively.

  15. Using In Situ Eddy Covariance Flux Measurements from a Low Flying Aircraft in the Arctic to Measure Regional Methane Fluxes.

    NASA Astrophysics Data System (ADS)

    Sayres, D. S.; Dobosy, R.; Healy, C. E.; Dumas, E. J.; Kochendorfer, J.; Munster, J. B.; Wilkerson, J.; Baker, B.; Anderson, J. G.

    2016-12-01

    The Arctic terrestrial and subsea permafrost region contains approximately 30% of the global carbon stock and therefore understanding Arctic methane emissions and how they might change with a changing climate is important for quantifying the global methane budget and understanding its growth in the atmosphere. Here we present measurements from a new in situ flux observation system designed for use on a small, low-flying aircraft that flew over the North Slope of Alaska during August of 2013. The system combines a small methane instrument based on Integrated Cavity Output Spectroscopy (ICOS) with an air turbulence probe to calculate methane fluxes based on eddy covariance. Surface fluxes are grouped by ecotope using a map based on LandSat 30 meter resolution data. We find that wet sedge areas dominate the methane fluxes during the first part of August, with methane emissions from the Sagavanirktok river being the second highest. We compare the aircraft measurements with an eddy covariance flux tower located in a wet sedge area and show that the two measurements agree quantitatively when the footprints of both overlap. However, fluxes from sedge vary at times by a factor of two or more even within a few kilometers of the tower demonstrating the importance of making regional measurements to map out methane emission spatial heterogeneity. Aircraft measurements of surface flux can play an important role in bridging the gap between ground-based measurements and regional measurements from remote sensing instruments and models.

  16. Heat flux measurement in SSME turbine blade tester

    NASA Astrophysics Data System (ADS)

    Liebert, Curt H.

    1990-11-01

    Surface heat flux values were measured in the turbine blade thermal cycling tester located at NASA-Marshall. This is the first time heat flux has been measured in a space shuttle main engine turbopump environment. Plots of transient and quasi-steady state heat flux data over a range of about 0 to 15 MW/sq m are presented. Data were obtained with a miniature heat flux gage device developed at NASA-Lewis. The results from these tests are being incorporated into turbine design models. Also, these gages are being considered for airfoil surface heat flux measurement on turbine vanes mounted in SSME turbopump test bed engine nozzles at Marshall. Heat flux effects that might be observed on degraded vanes are discussed.

  17. Heat flux measurement in SSME turbine blade tester

    NASA Astrophysics Data System (ADS)

    Liebert, Curt H.

    Surface heat flux values were measured in the turbine blade thermal cycling tester located at NASA-Marshall. This is the first time heat flux has been measured in a space shuttle main engine turbopump environment. Plots of transient and quasi-steady state heat flux data over a range of about 0 to 15 MW/sq m are presented. Data were obtained with a miniature heat flux gage device developed at NASA-Lewis. The results from these tests are being incorporated into turbine design models. Also, these gages are being considered for airfoil surface heat flux measurement on turbine vanes mounted in SSME turbopump test bed engine nozzles at Marshall. Heat flux effects that might be observed on degraded vanes are discussed.

  18. Measurement of local high-level, transient surface heat flux

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.

    1988-01-01

    This study is part of a continuing investigation to develop methods for measuring local transient surface heat flux. A method is presented for simultaneous measurements of dual heat fluxes at a surface location by considering the heat flux as a separate function of heat stored and heat conducted within a heat flux gage. Surface heat flux information is obtained from transient temperature measurements taken at points within the gage. Heat flux was determined over a range of 4 to 22 MW/sq m. It was concluded that the method is feasible. Possible applications are for heat flux measurements on the turbine blade surfaces of space shuttle main engine turbopumps and on the component surfaces of rocket and advanced gas turbine engines and for testing sensors in heat flux gage calibrators.

  19. Absolute shape measurements using high-resolution optoelectronic holography methods

    NASA Astrophysics Data System (ADS)

    Furlong, Cosme; Pryputniewicz, Ryszard J.

    2000-01-01

    Characterization of surface shape and deformation is of primary importance in a number of testing and metrology applications related to the functionality, performance, and integrity of components. In this paper, a unique, compact, and versatile state-of-the-art fiber-optic-based optoelectronic holography (OEH) methodology is described. This description addresses apparatus and analysis algorithms, especially developed to perform measurements of both absolute surface shape and deformation. The OEH can be arranged in multiple configurations, which include the three-camera, three-illumination, and in-plane speckle correlation setups. With the OEH apparatus and analysis algorithms, absolute shape measurements can be made, using present setup, with a spatial resolution and accuracy of better than 30 and 10 micrometers , respectively, for volumes characterized by a 300-mm length. Optimizing the experimental setup and incorporating equipment, as it becomes available, having superior capabilities to the ones utilized in the present investigations can further increase resolution and accuracy in the measurements. The particular feature of this methodology is its capability to export the measurements data directly into CAD environments for subsequent processing, analysis, and definition of CAD/CAE models.

  20. Latent heat sink in soil heat flux measurements

    USDA-ARS?s Scientific Manuscript database

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

  1. Measurement of absolute response functions and detection efficiencies of an NE213 scintillator up to 600 MeV

    NASA Astrophysics Data System (ADS)

    Kajimoto, Tsuyoshi; Shigyo, Nobuhiro; Sanami, Toshiya; Ishibashi, Kenji; Haight, Robert C.; Fotiades, Nikolaos

    2011-02-01

    Absolute neutron response functions and detection efficiencies of an NE213 liquid scintillator that was 12.7 cm in diameter and 12.7 cm in thickness were measured for neutron energies between 15 and 600 MeV at the Weapons Neutron Research facility of the Los Alamos Neutron Science Center. The experiment was performed with continuous-energy neutrons on a spallation neutron source by 800-MeV proton incidence. The incident neutron flux was measured using a 238U fission ionization chamber. Measured response functions and detection efficiencies were compared with corresponding calculations using the SCINFUL-QMD code. The calculated and experimental values were in good agreement for data below 70 MeV. However, there were discrepancies in the energy region between 70 and 150 MeV. Thus, the code was partly modified and the revised code provided better agreement with the experimental data.

  2. Eddy Correlation Flux Measurement System Handbook

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cook, D. R.

    2016-01-01

    The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration. The instruments used are: • a fast-response, three-dimensional (3D) wind sensor (sonic anemometer) to obtain the orthogonal wind componentsmore » and the speed of sound (SOS) (used to derive the air temperature) • an open-path infrared gas analyzer (IRGA) to obtain the water vapor density and the CO2 concentration, and • an open-path infrared gas analyzer (IRGA) to obtain methane density and methane flux at one SGP EF and at the NSA CF. The ECOR systems are deployed at the locations where other methods for surface flux measurements (e.g., energy balance Bowen ratio [EBBR] systems) are difficult to employ, primarily at the north edge of a field of crops. A Surface Energy Balance System (SEBS) has been installed collocated with each deployed ECOR system in SGP, NSA, Tropical Western Pacific (TWP), ARM Mobile Facility 1 (AMF1), and ARM Mobile Facility 2 (AMF2). The surface energy balance system consists of upwelling and downwelling solar and infrared radiometers within one net radiometer, a wetness sensor, and soil measurements. The SEBS measurements allow the comparison of ECOR sensible and latent heat fluxes with the energy balance determined from the SEBS and provide information on wetting of the sensors for data quality purposes. The SEBS at one SGP and one NSA site also support upwelling and downwelling PAR measurements to qualify those two locations as Ameriflux sites.« less

  3. Measuring Convective Mass Fluxes Over Tropical Oceans

    NASA Astrophysics Data System (ADS)

    Raymond, David

    2017-04-01

    Deep convection forms the upward branches of all large-scale circulations in the tropics. Understanding what controls the form and intensity of vertical convective mass fluxes is thus key to understanding tropical weather and climate. These mass fluxes and the corresponding conditions supporting them have been measured by recent field programs (TPARC/TCS08, PREDICT, HS3) in tropical disturbances considered to be possible tropical storm precursors. In reality, this encompasses most strong convection in the tropics. The measurements were made with arrays of dropsondes deployed from high altitude. In some cases Doppler radar provided additional measurements. The results are in some ways surprising. Three factors were found to control the mass flux profiles, the strength of total surface heat fluxes, the column-integrated relative humidity, and the low to mid-tropospheric moist convective instability. The first two act as expected, with larger heat fluxes and higher humidity producing more precipitation and stronger lower tropospheric mass fluxes. However, unexpectedly, smaller (but still positive) convective instability produces more precipitation as well as more bottom-heavy convective mass flux profiles. Furthermore, the column humidity and the convective instability are anti-correlated, at least in the presence of strong convection. On spatial scales of a few hundred kilometers, the virtual temperature structure appears to be in dynamic balance with the pattern of potential vorticity. Since potential vorticity typically evolves on longer time scales than convection, the potential vorticity pattern plus the surface heat fluxes then become the immediate controlling factors for average convective properties. All measurements so far have taken place in regions with relatively flat sea surface temperature (SST) distributions. We are currently seeking funding for a measurement program in the tropical east Pacific, a region that exhibits strong SST gradients and

  4. Pyrolytic graphite gauge for measuring heat flux

    NASA Technical Reports Server (NTRS)

    Bunker, Robert C. (Inventor); Ewing, Mark E. (Inventor); Shipley, John L. (Inventor)

    2002-01-01

    A gauge for measuring heat flux, especially heat flux encountered in a high temperature environment, is provided. The gauge includes at least one thermocouple and an anisotropic pyrolytic graphite body that covers at least part of, and optionally encases the thermocouple. Heat flux is incident on the anisotropic pyrolytic graphite body by arranging the gauge so that the gauge surface on which convective and radiative fluxes are incident is perpendicular to the basal planes of the pyrolytic graphite. The conductivity of the pyrolytic graphite permits energy, transferred into the pyrolytic graphite body in the form of heat flux on the incident (or facing) surface, to be quickly distributed through the entire pyrolytic graphite body, resulting in small substantially instantaneous temperature gradients. Temperature changes to the body can thereby be measured by the thermocouple, and reduced to quantify the heat flux incident to the body.

  5. Beta ray flux measuring device

    DOEpatents

    Impink, Jr., Albert J.; Goldstein, Norman P.

    1990-01-01

    A beta ray flux measuring device in an activated member in-core instrumentation system for pressurized water reactors. The device includes collector rings positioned about an axis in the reactor's pressure boundary. Activated members such as hydroballs are positioned within respective ones of the collector rings. A response characteristic such as the current from or charge on a collector ring indicates the beta ray flux from the corresponding hydroball and is therefore a measure of the relative nuclear power level in the region of the reactor core corresponding to the specific exposed hydroball within the collector ring.

  6. Accuracy of quantum sensors measuring yield photon flux and photosynthetic photon flux

    NASA Technical Reports Server (NTRS)

    Barnes, C.; Tibbitts, T.; Sager, J.; Deitzer, G.; Bubenheim, D.; Koerner, G.; Bugbee, B.; Knott, W. M. (Principal Investigator)

    1993-01-01

    Photosynthesis is fundamentally driven by photon flux rather than energy flux, but not all absorbed photons yield equal amounts of photosynthesis. Thus, two measures of photosynthetically active radiation have emerged: photosynthetic photon flux (PPF), which values all photons from 400 to 700 nm equally, and yield photon flux (YPF), which weights photons in the range from 360 to 760 nm according to plant photosynthetic response. We selected seven common radiation sources and measured YPF and PPF from each source with a spectroradiometer. We then compared these measurements with measurements from three quantum sensors designed to measure YPF, and from six quantum sensors designed to measure PPF. There were few differences among sensors within a group (usually <5%), but YPF values from sensors were consistently lower (3% to 20%) than YPF values calculated from spectroradiometric measurements. Quantum sensor measurements of PPF also were consistently lower than PPF values calculated from spectroradiometric measurements, but the differences were <7% for all sources, except red-light-emitting diodes. The sensors were most accurate for broad-band sources and least accurate for narrow-band sources. According to spectroradiometric measurements, YPF sensors were significantly less accurate (>9% difference) than PPF sensors under metal halide, high-pressure sodium, and low-pressure sodium lamps. Both sensor types were inaccurate (>18% error) under red-light-emitting diodes. Because both YPF and PPF sensors are imperfect integrators, and because spectroradiometers can measure photosynthetically active radiation much more accurately, researchers should consider developing calibration factors from spectroradiometric data for some specific radiation sources to improve the accuracy of integrating sensors.

  7. Heat-Flux Measurements from Collective Thomson-Scattering Spectra

    NASA Astrophysics Data System (ADS)

    Henchen, R. J.; Hu, S. X.; Katz, J.; Froula, D. H.; Rozmus, W.

    2015-11-01

    Collective Thomson scattering was used to measure heat flux in coronal plasmas. The relative amplitude of the Thomson-scattered power into the up- and downshifted electron plasma wave features was used to determine the flux of electrons moving along the temperature gradient at three to four times the electron thermal velocity. Simultaneously, the ion-acoustic wave features were measured. Their relative amplitude is used to measure the flux of the return-current electrons. The frequencies of these ion-acoustic and electron plasma wave features provide local measurements of the electron temperature and density. These spectra were obtained at five locations along the temperature gradient in a laser-produced blowoff plasma. These measurements of plasma parameters are used to infer the Spitzer -Härm flux qSH = - κ∇Te and are in good agreement with the values of the heat flux measured from the scattering-feature asymmetries. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  8. Heat flux measurements on ceramics with thin film thermocouples

    NASA Technical Reports Server (NTRS)

    Holanda, Raymond; Anderson, Robert C.; Liebert, Curt H.

    1993-01-01

    Two methods were devised to measure heat flux through a thick ceramic using thin film thermocouples. The thermocouples were deposited on the front and back face of a flat ceramic substrate. The heat flux was applied to the front surface of the ceramic using an arc lamp Heat Flux Calibration Facility. Silicon nitride and mullite ceramics were used; two thicknesses of each material was tested, with ceramic temperatures to 1500 C. Heat flux ranged from 0.05-2.5 MW/m2(sup 2). One method for heat flux determination used an approximation technique to calculate instantaneous values of heat flux vs time; the other method used an extrapolation technique to determine the steady state heat flux from a record of transient data. Neither method measures heat flux in real time but the techniques may easily be adapted for quasi-real time measurement. In cases where a significant portion of the transient heat flux data is available, the calculated transient heat flux is seen to approach the extrapolated steady state heat flux value as expected.

  9. Eddy Correlation Flux Measurement System (ECOR) Handbook

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cook, DR

    2011-01-31

    The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration.

  10. EUV mirror based absolute incident flux detector

    DOEpatents

    Berger, Kurt W.

    2004-03-23

    A device for the in-situ monitoring of EUV radiation flux includes an integrated reflective multilayer stack. This device operates on the principle that a finite amount of in-band EUV radiation is transmitted through the entire multilayer stack. This device offers improvements over existing vacuum photo-detector devices since its calibration does not change with surface contamination.

  11. Measurements of a Lee Wave in the Southern Ocean: Energy and Momentum Fluxes and Mixing

    NASA Astrophysics Data System (ADS)

    Cusack, J. M.; Naveira Garabato, A.; Smeed, D.; Girton, J. B.

    2016-02-01

    Lee waves, internal waves generated by stratified flow over topographic features are thought to break and generate a significant proportion of the turbulent mixing required to close the abyssal overturning circulation. A lack of observations means that there is large uncertainty in the magnitude of contribution that lee waves make to turbulent transformations, as well as their importance in local and global momentum and energy budgets. Two EM-APEX profiling floats deployed in the Drake Passage during the Diapycnal and Isopycnal Mixing Experiment (DIMES) independently measured a large lee wave over the Shackleton Fracture Zone. A model for steady EM-APEX motion is presented and used to calculate absolute vertical water velocity in addition to horizontal velocity measurements made by the floats. The wave is observed to have velocity fluctuations in all three directions of over 15 cm s-1 and a frequency close to the local buoyancy frequency. Furthermore, the wave has a measured peak vertical flux of horizontal momentum of 6 N m-2, a value that is two orders of magnitude larger than the time mean wind forcing on the Southern Ocean. Linear internal wave theory was used to estimate wave energy density and fluxes, while a mixing parameterisation was used to estimate the magnitude of turbulent kinetic energy dissipation, which was found to be elevated above typical background levels by two orders of magnitude. This work provides the first direct measurement of a lee wave generated by ACC flow over topography with simultaneous estimates of energy fluxes and mixing.

  12. Measured and modelled absolute gravity in Greenland

    NASA Astrophysics Data System (ADS)

    Nielsen, E.; Forsberg, R.; Strykowski, G.

    2012-12-01

    Present day changes in the ice volume in glaciated areas like Greenland will change the load on the Earth and to this change the lithosphere will respond elastically. The Earth also responds to changes in the ice volume over a millennial time scale. This response is due to the viscous properties of the mantle and is known as Glaical Isostatic Adjustment (GIA). Both signals are present in GPS and absolute gravity (AG) measurements and they will give an uncertainty in mass balance estimates calculated from these data types. It is possible to separate the two signals if both gravity and Global Positioning System (GPS) time series are available. DTU Space acquired an A10 absolute gravimeter in 2008. One purpose of this instrument is to establish AG time series in Greenland and the first measurements were conducted in 2009. Since then are 18 different Greenland GPS Network (GNET) stations visited and six of these are visited more then once. The gravity signal consists of three signals; the elastic signal, the viscous signal and the direct attraction from the ice masses. All of these signals can be modelled using various techniques. The viscous signal is modelled by solving the Sea Level Equation with an appropriate ice history and Earth model. The free code SELEN is used for this. The elastic signal is modelled as a convolution of the elastic Greens function for gravity and a model of present day ice mass changes. The direct attraction is the same as the Newtonian attraction and is calculated as this. Here we will present the preliminary results of the AG measurements in Greenland. We will also present modelled estimates of the direct attraction, the elastic and the viscous signals.

  13. Dual neutron flux/temperature measurement sensor

    DOEpatents

    Mihalczo, John T.; Simpson, Marc L.; McElhaney, Stephanie A.

    1994-01-01

    Simultaneous measurement of neutron flux and temperature is provided by a single sensor which includes a phosphor mixture having two principal constituents. The first constituent is a neutron sensitive 6LiF and the second is a rare-earth activated Y203 thermophosphor. The mixture is coated on the end of a fiber optic, while the opposite end of the fiber optic is coupled to a light detector. The detected light scintillations are quantified for neutron flux determination, and the decay is measured for temperature determination.

  14. Thorough subcells diagnosis in a multi-junction solar cell via absolute electroluminescence-efficiency measurements

    PubMed Central

    Chen, Shaoqiang; Zhu, Lin; Yoshita, Masahiro; Mochizuki, Toshimitsu; Kim, Changsu; Akiyama, Hidefumi; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

    2015-01-01

    World-wide studies on multi-junction (tandem) solar cells have led to record-breaking improvements in conversion efficiencies year after year. To obtain detailed and proper feedback for solar-cell design and fabrication, it is necessary to establish standard methods for diagnosing subcells in fabricated tandem devices. Here, we propose a potential standard method to quantify the detailed subcell properties of multi-junction solar cells based on absolute measurements of electroluminescence (EL) external quantum efficiency in addition to the conventional solar-cell external-quantum-efficiency measurements. We demonstrate that the absolute-EL-quantum-efficiency measurements provide I–V relations of individual subcells without the need for referencing measured I–V data, which is in stark contrast to previous works. Moreover, our measurements quantify the absolute rates of junction loss, non-radiative loss, radiative loss, and luminescence coupling in the subcells, which constitute the “balance sheets” of tandem solar cells. PMID:25592484

  15. Vertical divergence of fogwater fluxes above a spruce forest

    NASA Astrophysics Data System (ADS)

    Burkard, R.; Eugster, W.; Wrzesinsky, T.; Klemm, O.

    Two almost identical eddy covariance measurement setups were used to measure the fogwater fluxes to a forest ecosystem in the "Fichtelgebirge" mountains (Waldstein research site, 786 m a.s.l.) in Germany. During the first experiment, an intercomparison was carried out with both setups running simultaneously at the same measuring height on a meteorological tower, 12.5 m above the forest canopy. The results confirmed a close agreement of the turbulent fluxes between the two setups, and allowed to intercalibrate liquid water content (LWC) and gravitational fluxes. During the second experiment, the setups were mounted at a height of 12.5 and 3 m above the canopy, respectively. For the 22 fog events, a persistent negative flux divergence was observed with a greater downward flux at the upper level. To extrapolate the turbulent liquid water fluxes measured at height z to the canopy of height hc, a conversion factor 1/[1+0.116( z- hc)] was determined. For the fluxes of nonvolatile ions, no such correction is necessary since the net evaporation of the fog droplets appears to be the primary cause of the vertical flux divergence. Although the net evaporation reduces the liquid water flux reaching the canopy, it is not expected to change the absolute amount of ions dissolved in fogwater.

  16. An absolute cavity pyrgeometer to measure the absolute outdoor longwave irradiance with traceability to international system of units, SI

    NASA Astrophysics Data System (ADS)

    Reda, Ibrahim; Zeng, Jinan; Scheuch, Jonathan; Hanssen, Leonard; Wilthan, Boris; Myers, Daryl; Stoffel, Tom

    2012-03-01

    This article describes a method of measuring the absolute outdoor longwave irradiance using an absolute cavity pyrgeometer (ACP), U.S. Patent application no. 13/049, 275. The ACP consists of domeless thermopile pyrgeometer, gold-plated concentrator, temperature controller, and data acquisition. The dome was removed from the pyrgeometer to remove errors associated with dome transmittance and the dome correction factor. To avoid thermal convection and wind effect errors resulting from using a domeless thermopile, the gold-plated concentrator was placed above the thermopile. The concentrator is a dual compound parabolic concentrator (CPC) with 180° view angle to measure the outdoor incoming longwave irradiance from the atmosphere. The incoming irradiance is reflected from the specular gold surface of the CPC and concentrated on the 11 mm diameter of the pyrgeometer's blackened thermopile. The CPC's interior surface design and the resulting cavitation result in a throughput value that was characterized by the National Institute of Standards and Technology. The ACP was installed horizontally outdoor on an aluminum plate connected to the temperature controller to control the pyrgeometer's case temperature. The responsivity of the pyrgeometer's thermopile detector was determined by lowering the case temperature and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The responsivity is then used to calculate the absolute atmospheric longwave irradiance with an uncertainty estimate (U95) of ±3.96 W m-2 with traceability to the International System of Units, SI. The measured irradiance was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the Interim World Infrared Standard Group, WISG. A total of 408 readings were collected over three different nights. The calculated irradiance measured by the ACP was 1.5 W/m2 lower than that measured by the two

  17. Dual neutron flux/temperature measurement sensor

    DOEpatents

    Mihalczo, J.T.; Simpson, M.L.; McElhaney, S.A.

    1994-10-04

    Simultaneous measurement of neutron flux and temperature is provided by a single sensor which includes a phosphor mixture having two principal constituents. The first constituent is a neutron sensitive 6LiF and the second is a rare-earth activated Y203 thermophosphor. The mixture is coated on the end of a fiber optic, while the opposite end of the fiber optic is coupled to a light detector. The detected light scintillations are quantified for neutron flux determination, and the decay is measured for temperature determination. 3 figs.

  18. NIST Stars: Absolute Spectrophotometric Calibration of Vega and Sirius

    NASA Astrophysics Data System (ADS)

    Deustua, Susana; Woodward, John T.; Rice, Joseph P.; Brown, Steven W.; Maxwell, Stephen E.; Alberding, Brian G.; Lykke, Keith R.

    2018-01-01

    Absolute flux calibration of standard stars, traceable to SI (International System of Units) standards, is essential for 21st century astrophysics. Dark energy investigations that rely on observations of Type Ia supernovae and precise photometric redshifts of weakly lensed galaxies require a minimum accuracy of 0.5 % in the absolute color calibration. Studies that aim to address fundamental stellar astrophysics also benefit. In the era of large telescopes and all sky surveys well-calibrated standard stars that do not saturate and that are available over the whole sky are needed. Significant effort has been expended to obtain absolute measurements of the fundamental standards Vega and Sirius (and other stars) in the visible and near infrared, achieving total uncertainties between1% and 3%, depending on wavelength, that do not meet the needed accuracy. The NIST Stars program aims to determine the top-of-the-atmosphere absolute spectral irradiance of bright stars to an uncertainty less than 1% from a ground-based observatory. NIST Stars has developed a novel, fully SI-traceable laboratory calibration strategy that will enable achieving the desired accuracy. This strategy has two key components. The first is the SI-traceable calibration of the entire instrument system, and the second is the repeated spectroscopic measurement of the target star throughout the night. We will describe our experimental strategy, present preliminary results for Vega and Sirius and an end-to-end uncertainty budget

  19. Airborne flux measurements of Biogenic Isoprene over California

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Misztal, P.; Karl, Thomas G.; Weber, Robin

    2014-10-10

    Biogenic Volatile Organic Compound (BVOC) fluxes were measured onboard the CIRPAS Twin Otter aircraft as part of the California Airborne BVOC Emission Research in Natural Ecosystem Transects (CABERNET) campaign during June 2011. The airborne virtual disjunct eddy covariance (AvDEC) approach used measurements from a PTR-MS and a wind radome probe to directly determine fluxes of isoprene, MVK+MAC, methanol, monoterpenes, and MBO over ~10,000-km of flight paths focusing on areas of California predicted to have the largest emissions of isoprene. The Fast Fourier Transform (FFT) approach was used to calculate fluxes over long transects of more than 15 km, most commonlymore » between 50 and 150 km. The Continuous Wavelet Transformation (CWT) approach was used over the same transects to also calculate "instantaneous" fluxes with localization of both frequency and time independent of non-stationarities. Vertical flux divergence of isoprene is expected due to its relatively short lifetime and was measured directly using "racetrack" profiles at multiple altitudes. It was found to be linear and in the range 5% to 30% depending on the ratio of aircraft altitude to PBL height (z/zi). Fluxes were generally measured by flying consistently 1 at 400 m ±50 m (a.g.l.) altitude, and extrapolated to the surface according to the determined flux divergence. The wavelet-derived surface fluxes of isoprene averaged to 2 km spatial resolution showed good correspondence to Basal Emission Factor (BEF) landcover datasets used to drive biogenic VOC (BVOC) emission models. The surface flux of isoprene was close to zero over Central Valley crops and desert shrublands, but was very high (up to 15 mg m-2 h-1) above oak woodlands, with clear dependence of emissions on temperature and oak density. Isoprene concentrations of up to 8 ppb were observed at aircraft height on the hottest days and over the dominant source regions. While isoprene emissions from agricultural crop regions, shrublands, and

  20. Absolute Calibration of the AXAF Telescope Effective Area

    NASA Technical Reports Server (NTRS)

    Kellogg, E.; Cohen, L.; Edgar, R.; Evans, I.; Freeman, M.; Gaetz, T.; Jerius, D.; McDermott, W. C.; McKinnon, P.; Murray, S.; hide

    1997-01-01

    The prelaunch calibration of AXAF encompasses many aspects of the telescope. In principle, all that is needed is the complete point response function. This is, however, a function of energy, off-axis angle of the source, and operating mode of the facility. No single measurement would yield the entire result. Also, any calibration made prior to launch will be affected by changes in conditions after launch, such as the change from one g to zero g. The reflectivity of the mirror and perhaps even the detectors can change as well, for example by addition or removal of small amounts of material deposited on their surfaces. In this paper, we give a broad view of the issues in performing such a calibration, and discuss how they are being addressed in prelaunch preparation of AXAF. As our title indicates, we concentrate here on the total throughput of the observatory. This can be thought of as the integral of the point response function, i.e. the encircled energy, out ot the largest practical solid angle for an observation. Since there is no standard x-ray source in the sky whose flux is known to the -1% accuracy we are trying to achieve, we must do this calibration on the ground. we also must provide a means for monitoring any possible changes in this calibration from pre-launch until on-orbit operation can transfer the calibration to a celestial x-ray source whose emission is stable. In this paper, we analyze the elements of the absolute throughput calibration, which we call Effective Area. We review the requirements for calibrations of components or subsystems of the AXAF facility, including mirror, detectors, and gratings. We show how it is necessary to calibrate this ground-based detection system at standard man-made x-ray sources, such as electron storage rings. We present the status of all these calibrations, with indications of the measurements remaining to be done, even though the measurements on the AXAF flight optics and detectors will have been completed by the

  1. Sub µGal Absolute Gravity Measurements with a Transportable Quantum Gravimeter

    NASA Astrophysics Data System (ADS)

    Desruelle, B.; Vermeulen, P.; Menoret, V.; Landragin, A.; Bouyer, P.; Le Moigne, N.; Gabalda, G.; Bonvalot, S.

    2017-12-01

    This paper presents a review of the last two years of operation of the first unit of the Absolute Quantum Gravimeter (AQG). The AQG is an industry-grade commercial gravimeter, which validates the feasibility to develop a matter-wave gravimeter as a transportable turn-key device. We will discuss the stability of the absolute measurement of g and demonstrate the capability of our instrument to achieve a sensitivity better than 1 µGal in various types of environment. We will in particular comment on the last measurement campaigns and comparisons performed by the AQG which have validated the ease of use and the robustness of the sensor. This paper will also present the status of the development of the field version of the AQG designed to be compatible with outdoor operation.

  2. Eddy-covariance methane flux measurements over a European beech forest

    NASA Astrophysics Data System (ADS)

    Gentsch, Lydia; Siebicke, Lukas; Knohl, Alexander

    2015-04-01

    The role of forests in global methane (CH4) turnover is currently not well constrained, partially because of the lack of spatially integrative forest-scale measurements of CH4 fluxes. Soil chamber measurements imply that temperate forests generally act as CH4 sinks. Upscaling of chamber observations to the forest scale is however problematic, if the upscaling is not constrained by concurrent 'top-down' measurements, such as of the eddy-covariance type, which provide sufficient integration of spatial variations and of further potential CH4 flux components within forest ecosystems. Ongoing development of laser absorption-based optical instruments, resulting in enhanced measurement stability, precision and sampling speed, has recently improved the prospects for meaningful eddy-covariance measurements at sites with presumably low CH4 fluxes, hence prone to reach the flux detection limit. At present, we are launching eddy-covariance CH4 measurements at a long-running ICOS flux tower site (Hainich National Park, Germany), located in a semi natural, unmanaged, beech dominated forest. Eddy-covariance measurements will be conducted with a laser spectrometer for parallel CH4, H2Ov and CO2 measurements (FGGA, Los Gatos Research, USA). Independent observations of the CO2 flux by the FGGA and a standard Infrared Gas Analyser (LI-7200, LI-COR, USA) will allow to evaluate data quality of measured CH4 fluxes. Here, we want to present first results with a focus on uncertainties of the calculated CH4 fluxes with regard to instrument precision, data processing and site conditions. In future, we plan to compare eddy-covariance flux estimates to side-by-side turbulent flux observations from a novel eddy accumulation system. Furthermore, soil CH4 fluxes will be measured with four automated chambers situated within the tower footprint. Based on a previous soil chamber study at the same site, we expect the Hainich forest site to act as a CH4 sink. However, we hypothesize that our

  3. Measurement of absolute lung volumes by imaging techniques.

    PubMed

    Clausen, J

    1997-10-01

    In this paper, the techniques available for estimating total lung capacities from standard chest radiographs in children and infants as well as adults are reviewed. These techniques include manual measurements using ellipsoid and planimetry techniques as well as computerized systems. Techniques are also available for making radiographic lung volume measurements from portable chest radiographs. There are inadequate data in the literature to support recommending one specific technique over another. Though measurements of lung volumes by radiographic, plethysmographic, gas dilution or washout techniques result in remarkably similar mean results when groups of normal subjects are tested, in patients with disease, the results of these different basic measurement techniques can differ significantly. Computed tomographic and magnetic resonance techniques can also be used to measure absolute lung volumes and offer the theoretical advantages that the results in individual subjects are less affected by variances of thoracic shape than are measurements made using conventional chest radiographs.

  4. Metabolite concentrations, fluxes and free energies imply efficient enzyme usage

    DOE PAGES

    Park, Junyoung O.; Rubin, Sara A.; Xu, Yi -Fan; ...

    2016-05-02

    In metabolism, available free energy is limited and must be divided across pathway steps to maintain a negative Δ G throughout. For each reaction, Δ G is log proportional both to a concentration ratio (reaction quotient to equilibrium constant) and to a flux ratio (backward to forward flux). In this paper, we use isotope labeling to measure absolute metabolite concentrations and fluxes in Escherichia coli, yeast and a mammalian cell line. We then integrate this information to obtain a unified set of concentrations and Δ G for each organism. In glycolysis, we find that free energy is partitioned so asmore » to mitigate unproductive backward fluxes associated with Δ G near zero. Across metabolism, we observe that absolute metabolite concentrations and Δ G are substantially conserved and that most substrate (but not inhibitor) concentrations exceed the associated enzyme binding site dissociation constant ( K m or K i). Finally, the observed conservation of metabolite concentrations is consistent with an evolutionary drive to utilize enzymes efficiently given thermodynamic and osmotic constraints.« less

  5. The area and absolute magnetic flux of sunspots over the past 400 years

    NASA Astrophysics Data System (ADS)

    Nagovitsyn, Yu. A.; Tlatov, A. G.; Nagovitsyna, E. Yu.

    2016-09-01

    A new series of yearly-mean relative sunspot numbers SN 2 that has been extrapolated into the past (to 1610) is presented. The Kislovodsk series with the scale factor b = 1.0094 ± 0.0059 represents a reasonable continuation of the mean-monthly and mean-yearly total sunspot areas of the Greenwich series after 1976. The second maximum of the 24th solar-activity cycle was not anomalously low, and was no lower than 6 of the past 13 cycles. A series A 2 of values for the total sunspot area in 1610-2015 has been constructed, and is complementary to new versions of the series of the relative number of sunspots SN 2 and the number of sunspot groups GN 2. When needed, this series can be reduced to yield a quantity having a clear physical meaning—the spot absolute magnetic flux Φ Σ( t)[Mx] = 2.16 × 1019 A( t) [mvh]. The maximum sunspot area during the Maunder minimum is much higher in the new series compared to the previous version. This at least partially supports the validity of arguments that cast doubt on the anomalously low ampltude of the solar cycles during the Maunder minimum that has been assumed by many researchers earlier.

  6. Fundamentals of heat measurement. [heat flux transducers

    NASA Technical Reports Server (NTRS)

    Gerashchenko, O. A.

    1979-01-01

    Various methods and devices for obtaining experimental data on heat flux density over wide ranges of temperature and pressure are examined. Laboratory tests and device fabrication details are supplemented by theoretical analyses of heat-conduction and thermoelectric effects, providing design guidelines and information relevant to further research and development. A theory defining the measure of correspondence between transducer signal and the measured heat flux is established for individual (isolated) heat flux transducers subject to space and time-dependent loading. An analysis of the properties of stacked (series-connected) transducers of various types (sandwich-type, plane, and spiral) is used to derive a similarity theory providing general governing relationships. The transducers examined are used in 36 types of derivative devices involving direct heat loss measurements, heat conduction studies, radiation pyrometry, calorimetry in medicine and industry and nuclear reactor dosimetry.

  7. Sensors for Metering Heat Flux Area Density and Metrological Equipment for the Heat Flux Density Measurement

    NASA Astrophysics Data System (ADS)

    Doronin, D. O.

    2018-04-01

    The demand in measuring and studies of heat conduction of various media is very urgent now. This article considers the problem of heat conduction monitoring and measurement in various media and materials in any industries and branches of science as well as metrological support of the heat flux measurement equipment. The main study objects are both the sensors manufactured and facilities onto which these sensors will be installed: different cladding structures of the buildings, awnings, rocket fairings, boiler units, internal combustion engines. The Company develops and manufactures different types of heat flux sensors: thermocouple, thin-film, heterogeneous gradient as well as metrological equipment for the gauging calibration of the heat flux density measurement. The calibration shall be performed using both referencing method in the unit and by fixed setting of the heat flux in the unit. To manufacture heterogeneous heat flux gradient sensors (HHFGS) the Company developed and designed a number of units: diffusion welding unit, HHFGS cutting unit. Rather good quality HHFGS prototypes were obtained. At this stage the factory tests on the equipment for the heat flux density measurement equipment are planned. A high-sensitivity heat flux sensor was produced, now it is tested at the Construction Physics Research Institute (Moscow). It became possible to create thin-film heat flux sensors with the sensitivity not worse than that of the sensors manufactured by Captec Company (France). The Company has sufficient premises to supply the market with a wide range of sensors, to master new sensor manufacture technologies which will enable their application range.

  8. Spatial carrier color digital speckle pattern interferometry for absolute three-dimensional deformation measurement

    NASA Astrophysics Data System (ADS)

    Gao, Xinya; Wang, Yonghong; Li, Junrui; Dan, Xizuo; Wu, Sijin; Yang, Lianxiang

    2017-06-01

    It is difficult to measure absolute three-dimensional deformation using traditional digital speckle pattern interferometry (DSPI) when the boundary condition of an object being tested is not exactly given. In practical applications, the boundary condition cannot always be specifically provided, limiting the use of DSPI in real-world applications. To tackle this problem, a DSPI system that is integrated by the spatial carrier method and a color camera has been established. Four phase maps are obtained simultaneously by spatial carrier color-digital speckle pattern interferometry using four speckle interferometers with different illumination directions. One out-of-plane and two in-plane absolute deformations can be acquired simultaneously without knowing the boundary conditions using the absolute deformation extraction algorithm based on four phase maps. Finally, the system is proved by experimental results through measurement of the deformation of a flat aluminum plate with a groove.

  9. The brightness temperature of Venus and the absolute flux-density scale at 608 MHz.

    NASA Technical Reports Server (NTRS)

    Muhleman, D. O.; Berge, G. L.; Orton, G. S.

    1973-01-01

    The disk temperature of Venus was measured at 608 MHz near the inferior conjunction of 1972, and a value of 498 plus or minus 33 K was obtained using a nominal CKL flux-density scale. The result is consistent with earlier measurements, but has a much smaller uncertainty. Our theoretical model prediction is larger by a factor of 1.21 plus or minus 0.09. This discrepancy has been noticed previously for frequencies below 1400 MHz, but was generally disregarded because of the large observational uncertainties. No way could be found to change the model to produce agreement without causing a conflict with well-established properties of Venus. Thus it is suggested that the flux-density scale may require an upward revision, at least near this frequency, in excess of what has previously been considered likely.

  10. Absolute calibration of a charge-coupled device camera with twin beams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Meda, A.; Ruo-Berchera, I., E-mail: i.ruoberchera@inrim.it; Degiovanni, I. P.

    2014-09-08

    We report on the absolute calibration of a Charge-Coupled Device (CCD) camera by exploiting quantum correlation. This method exploits a certain number of spatial pairwise quantum correlated modes produced by spontaneous parametric-down-conversion. We develop a measurement model accounting for all the uncertainty contributions, and we reach the relative uncertainty of 0.3% in low photon flux regime. This represents a significant step forward for the characterization of (scientific) CCDs used in mesoscopic light regime.

  11. Absolute flatness measurements of silicon mirrors by a three-intersection method by near-infrared interferometry

    PubMed Central

    2013-01-01

    Absolute flatness of three silicon plane mirrors have been measured by a three-intersection method based on the three-flat method using a near-infrared interferometer. The interferometer was constructed using a near-infrared laser diode with a 1,310-nm wavelength light where the silicon plane mirror is transparent. The height differences at the coordinate values between the absolute line profiles by the three-intersection method have been evaluated. The height differences of the three flats were 4.5 nm or less. The three-intersection method using the near-infrared interferometer was useful for measuring the absolute flatness of the silicon plane mirrors. PMID:23758916

  12. Measuring Subsurface Water Fluxes Using a Heat Pulse Sensor

    NASA Astrophysics Data System (ADS)

    Ochsner, T. E.; Wang, Q.; Horton, R.

    2001-12-01

    Subsurface water flux is an important parameter in studies of runoff, infiltration, groundwater recharge, and subsurface chemical transport. Heat pulse sensors have been proposed as promising tools for measuring subsurface water fluxes. Our heat pulse probe consists of three 4-cm stainless-steel needles embedded in a waterproof epoxy body. The needles contain resistance heaters and thermocouples. The probes are connected to an external datalogger and power supply and then installed in soil. To measure the water flux, a 15-s heat pulse is generated at the middle needle using the power supply and the resistance heater, and the temperature increases at the needles 6-mm upstream and downstream from the heater are recorded using the thermocouples and datalogger. To date, heat pulse methods have required cumbersome mathematical analysis to calculate soil water flux from this measured data. We present a new mathematical analysis showing that a simple relationship exists between water flux and the ratio of the temperature increase downstream from the line heat source to the temperature increase upstream from the line heat source. The simplicity of this relationship makes heat pulse sensors a more attractive option for measuring subsurface water fluxes.

  13. Directly relating gas-phase cluster measurements to solution-phase hydrolysis, the absolute standard hydrogen electrode potential, and the absolute proton solvation energy.

    PubMed

    Donald, William A; Leib, Ryan D; O'Brien, Jeremy T; Williams, Evan R

    2009-06-08

    Solution-phase, half-cell potentials are measured relative to other half-cell potentials, resulting in a thermochemical ladder that is anchored to the standard hydrogen electrode (SHE), which is assigned an arbitrary value of 0 V. A new method for measuring the absolute SHE potential is demonstrated in which gaseous nanodrops containing divalent alkaline-earth or transition-metal ions are reduced by thermally generated electrons. Energies for the reactions 1) M(H(2)O)(24)(2+)(g) + e(-)(g)-->M(H(2)O)(24)(+)(g) and 2) M(H(2)O)(24)(2+)(g) + e(-)(g)-->MOH(H(2)O)(23)(+)(g) + H(g) and the hydrogen atom affinities of MOH(H(2)O)(23)(+)(g) are obtained from the number of water molecules lost through each pathway. From these measurements on clusters containing nine different metal ions and known thermochemical values that include solution hydrolysis energies, an average absolute SHE potential of +4.29 V vs. e(-)(g) (standard deviation of 0.02 V) and a real proton solvation free energy of -265 kcal mol(-1) are obtained. With this method, the absolute SHE potential can be obtained from a one-electron reduction of nanodrops containing divalent ions that are not observed to undergo one-electron reduction in aqueous solution.

  14. Directly Relating Gas-Phase Cluster Measurements to Solution-Phase Hydrolysis, the Absolute Standard Hydrogen Electrode Potential, and the Absolute Proton Solvation Energy

    PubMed Central

    Donald, William A.; Leib, Ryan D.; O’Brien, Jeremy T.; Williams, Evan R.

    2009-01-01

    Solution-phase, half-cell potentials are measured relative to other half-cell potentials, resulting in a thermochemical ladder that is anchored to the standard hydrogen electrode (SHE), which is assigned an arbitrary value of 0 V. A new method for measuring the absolute SHE potential is demonstrated in which gaseous nanodrops containing divalent alkaline-earth or transition-metal ions are reduced by thermally generated electrons. Energies for the reactions 1) M-(H2O)242+(g)+e−(g)→M(H2O)24+(g) and 2) M(H2O)242+(g)+e−(g)→MOH(H2O)23+(g)+H(g) and the hydrogen atom affinities of MOH(H2O)23+(g) are obtained from the number of water molecules lost through each pathway. From these measurements on clusters containing nine different metal ions and known thermochemical values that include solution hydrolysis energies, an average absolute SHE potential of +4.29 V vs. e−(g) (standard deviation of 0.02 V) and a real proton solvation free energy of −265 kcal mol−1 are obtained. With this method, the absolute SHE potential can be obtained from a one-electron reduction of nanodrops containing divalent ions that are not observed to undergo one-electron reduction in aqueous solution. PMID:19440999

  15. HST/WFC3 flux calibration ladder: Vega

    NASA Astrophysics Data System (ADS)

    Deustua, Susana E.; Bohlin, Ralph; Pirzkal, Nor; MacKenty, John

    2014-08-01

    Vega is one of only a few stars calibrated against an SI-traceable blackbody, and is the historical flux standard. Photometric zeropoints of the Hubble Space Telescope's instruments rely on Vega, through the transfer of its calibration via stellar atmosphere models to the suite of standard stars. HST's recently implemented scan mode has enabled us to develop a path to an absolute SI traceable calibration for HST IR observations. To fill in the crucial gap between 0.9 and 1.7 micron in the absolute calibration, we acquired -1st order spectra of Vega with the two WFC3 infrared grisms. At the same time, we have improved the calibration of the -1st orders of both WFC3 IR grisms, as well as extended the dynamic range of WFC3 science observations by a factor of 10000. We describe our progress to date on the WFC3 `flux calibration ladder' project to provide currently needed accurate zeropoint measurements in the IR

  16. Absolute Soft X-ray Emission Measurements at the Nike Laser

    NASA Astrophysics Data System (ADS)

    Weaver, J.; Atkin, R.; Boyer, C.; Colombant, D.; Feldman, U.; Fielding, D.; Gardner, J.; Holland, G.; Klapisch, M.; Mostovych, A. N.; Obenscain, S.; Seely, J. F.

    2002-11-01

    Recent experiments at the Nike laser facility have demonstrated that, when a low intensity prepulse ( 2main laser intensity) is used to heat a thin Au or Pd coating on a planar CH target, the growth of non-uniformities due to laser imprint can be reduced from the growth observed for an uncoated CH target. The absolute radiation intensity in the soft x-ray region (0.1-1 keV) has a important role in the energy balance for layered targets. There is an ongoing effort to characterize the soft x-ray emission using an absolutely calibrated transmission grating spectrometer and filtered diode modules. Measurements of the angular distribution of the emission from unlayered solid targets (Au, Pd, CH) have recently been made using an array of moveable filtered diode modules. The data from the angular distribution studies will be presented. A new absolutely calibrated, time-resolving transmission grating spectrometer has been installed at the Nike. The new version has improved spectral resolution, selectable transmission filters, and the potential for simultaneous temporal, spatial, and spectral resolution. Preliminary data from the new spectrometer will be presented and future experiments will be briefly discussed. *Work was supported by DoE

  17. Calibration-free absolute frequency response measurement of directly modulated lasers based on additional modulation.

    PubMed

    Zhang, Shangjian; Zou, Xinhai; Wang, Heng; Zhang, Yali; Lu, Rongguo; Liu, Yong

    2015-10-15

    A calibration-free electrical method is proposed for measuring the absolute frequency response of directly modulated semiconductor lasers based on additional modulation. The method achieves the electrical domain measurement of the modulation index of directly modulated lasers without the need for correcting the responsivity fluctuation in the photodetection. Moreover, it doubles measuring frequency range by setting a specific frequency relationship between the direct and additional modulation. Both the absolute and relative frequency response of semiconductor lasers are experimentally measured from the electrical spectrum of the twice-modulated optical signal, and the measured results are compared to those obtained with conventional methods to check the consistency. The proposed method provides calibration-free and accurate measurement for high-speed semiconductor lasers with high-resolution electrical spectrum analysis.

  18. First UAV Measurements of Entrainment Layer Fluxes with Coupled Cloud Property Measurements

    NASA Astrophysics Data System (ADS)

    Thomas, R. M.; Praveen, P. S.; Wilcox, E. M.; Pistone, K.; Bender, F.; Ramanathan, V.

    2012-12-01

    This study details entrainment flux measurements made from a lightweight unmanned aerial vehicle (UAV) containing turbulent water vapor flux instrumentation (Thomas et al., 2012). The system was flown for 26 flights during the Cloud, Aerosol, Radiative forcing, Dynamics EXperiment (CARDEX) in the Maldives in March 2012 to study interrelationships between entrainment, aerosols, water budget, cloud microphysics and radiative fluxes in a trade wind cumulus cloud regime. A major advantage of using this lightweight, precision autopiloted UAV system with scientific telemetry is the ability to target small-scale features in the boundary layer, such as an entrainment layer, with minimal aircraft induced disruption. Results are presented from two UAVs flown in stacked formation: one UAV situated in-cloud measuring cloud-droplet size distribution spectra and liquid water content, and another co-located 100m above measuring turbulent properties and entrainment latent heat flux (λEE). We also show latent heat flux and turbulence measurements routinely made at the entrainment layer base and altitudes from the surface up to 4kft. Ratios of λEE to corresponding surface tower values (λES) display a bimodal frequency distribution with ranges 0.22-0.53 and 0.79-1.5, with occasional events >7. Reasons for this distribution are discussed drawing upon boundary layer and free tropospheric dynamics and meteorology, turbulence length scales, surface conditions, and cloud interactions. Latent heat flux profiles are combined with in-cloud UAV Liquid Water Content (LWC) data and surface based Liquid Water Path (LWP) and Precipitable Water Vapor (PWV) measurements to produce observationally constrained vertical water budgets, providing insights into diurnal coupling of λEE and λES. Observed λEE, λES, water budgets, and cloud microphysical responses to entrainment are then contextualized with respect to measured aerosol loading profiles and airmass history.

  19. Uncertainty analysis technique for OMEGA Dante measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    May, M. J.; Widmann, K.; Sorce, C.

    2010-10-15

    The Dante is an 18 channel x-ray filtered diode array which records the spectrally and temporally resolved radiation flux from various targets (e.g., hohlraums, etc.) at x-ray energies between 50 eV and 10 keV. It is a main diagnostic installed on the OMEGA laser facility at the Laboratory for Laser Energetics, University of Rochester. The absolute flux is determined from the photometric calibration of the x-ray diodes, filters and mirrors, and an unfold algorithm. Understanding the errors on this absolute measurement is critical for understanding hohlraum energetic physics. We present a new method for quantifying the uncertainties on the determinedmore » flux using a Monte Carlo parameter variation technique. This technique combines the uncertainties in both the unfold algorithm and the error from the absolute calibration of each channel into a one sigma Gaussian error function. One thousand test voltage sets are created using these error functions and processed by the unfold algorithm to produce individual spectra and fluxes. Statistical methods are applied to the resultant set of fluxes to estimate error bars on the measurements.« less

  20. Uncertainty Analysis Technique for OMEGA Dante Measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    May, M J; Widmann, K; Sorce, C

    2010-05-07

    The Dante is an 18 channel X-ray filtered diode array which records the spectrally and temporally resolved radiation flux from various targets (e.g. hohlraums, etc.) at X-ray energies between 50 eV to 10 keV. It is a main diagnostics installed on the OMEGA laser facility at the Laboratory for Laser Energetics, University of Rochester. The absolute flux is determined from the photometric calibration of the X-ray diodes, filters and mirrors and an unfold algorithm. Understanding the errors on this absolute measurement is critical for understanding hohlraum energetic physics. We present a new method for quantifying the uncertainties on the determinedmore » flux using a Monte-Carlo parameter variation technique. This technique combines the uncertainties in both the unfold algorithm and the error from the absolute calibration of each channel into a one sigma Gaussian error function. One thousand test voltage sets are created using these error functions and processed by the unfold algorithm to produce individual spectra and fluxes. Statistical methods are applied to the resultant set of fluxes to estimate error bars on the measurements.« less

  1. Real-Time and Meter-Scale Absolute Distance Measurement by Frequency-Comb-Referenced Multi-Wavelength Interferometry.

    PubMed

    Wang, Guochao; Tan, Lilong; Yan, Shuhua

    2018-02-07

    We report on a frequency-comb-referenced absolute interferometer which instantly measures long distance by integrating multi-wavelength interferometry with direct synthetic wavelength interferometry. The reported interferometer utilizes four different wavelengths, simultaneously calibrated to the frequency comb of a femtosecond laser, to implement subwavelength distance measurement, while direct synthetic wavelength interferometry is elaborately introduced by launching a fifth wavelength to extend a non-ambiguous range for meter-scale measurement. A linearity test performed comparatively with a He-Ne laser interferometer shows a residual error of less than 70.8 nm in peak-to-valley over a 3 m distance, and a 10 h distance comparison is demonstrated to gain fractional deviations of ~3 × 10 -8 versus 3 m distance. Test results reveal that the presented absolute interferometer enables precise, stable, and long-term distance measurements and facilitates absolute positioning applications such as large-scale manufacturing and space missions.

  2. An automated LS(β)- NaI(Tl)(γ) coincidence system as absolute standard for radioactivity measurements.

    PubMed

    Joseph, Leena; Das, A P; Ravindra, Anuradha; Kulkarni, D B; Kulkarni, M S

    2018-07-01

    4πβ-γ coincidence method is a powerful and widely used method to determine the absolute activity concentration of radioactive solutions. A new automated liquid scintillator based coincidence system has been designed, developed, tested and established as absolute standard for radioactivity measurements. The automation is achieved using PLC (programmable logic controller) and SCADA (supervisory control and data acquisition). Radioactive solution of 60 Co was standardized to compare the performance of the automated system with proportional counter based absolute standard maintained in the laboratory. The activity concentrations determined using these two systems were in very good agreement; the new automated system can be used for absolute measurement of activity concentration of radioactive solutions. Copyright © 2018. Published by Elsevier Ltd.

  3. Elevation correction factor for absolute pressure measurements

    NASA Technical Reports Server (NTRS)

    Panek, Joseph W.; Sorrells, Mark R.

    1996-01-01

    With the arrival of highly accurate multi-port pressure measurement systems, conditions that previously did not affect overall system accuracy must now be scrutinized closely. Errors caused by elevation differences between pressure sensing elements and model pressure taps can be quantified and corrected. With multi-port pressure measurement systems, the sensing elements are connected to pressure taps that may be many feet away. The measurement system may be at a different elevation than the pressure taps due to laboratory space or test article constraints. This difference produces a pressure gradient that is inversely proportional to height within the interface tube. The pressure at the bottom of the tube will be higher than the pressure at the top due to the weight of the tube's column of air. Tubes with higher pressures will exhibit larger absolute errors due to the higher air density. The above effect is well documented but has generally been taken into account with large elevations only. With error analysis techniques, the loss in accuracy from elevation can be easily quantified. Correction factors can be applied to maintain the high accuracies of new pressure measurement systems.

  4. A Preliminary Study of CO2 Flux Measurements by Lidar

    NASA Technical Reports Server (NTRS)

    Gibert, Fabien; Koch, Grady J.; Beyon, Jeffrey Y.; Hilton, T.; Davis, Kenneth J.; Andrews, Arlyn; Ismail, Syed; Singh, Upendra N.

    2008-01-01

    A mechanistic understanding of the global carbon cycle requires quantification of terrestrial ecosystem CO2 fluxes at regional scales. In this paper, we analyze the potential of a Doppler DIAL system to make flux measurements of atmospheric CO2 using the eddy-covariance and boundary layer budget methods and present results from a ground based experiment. The goal of this study is to put CO2 flux point measurements in a mesoscale context. In June 2007, a field experiment combining a 2-m Doppler Heterodyne Differential Absorption Lidar (HDIAL) and in-situ sensors of a 447-m tall tower (WLEF) took place in Wisconsin. The HDIAL measures simultaneously: 1) CO2 mixing ratio, 2) atmosphere structure via aerosol backscatter and 3) radial velocity. We demonstrate how to synthesize these data into regional flux estimates. Lidar-inferred fluxes are compared with eddy-covariance fluxes obtained in-situ at 396m AGL from the tower. In cases where the lidar was not yet able to measure the fluxes with acceptable precision, we discuss possible modifications to improve system performance.

  5. Absolute stress measurements at the rangely anticline, Northwestern Colorado

    USGS Publications Warehouse

    de la Cruz, R. V.; Raleigh, C.B.

    1972-01-01

    Five different methods of measuring absolute state of stress in rocks in situ were used at sites near Rangely, Colorado, and the results compared. For near-surface measurements, overcoring of the borehole-deformation gage is the most convenient and rapid means of obtaining reliable values for the magnitude and direction of the state of stress in rocks in situ. The magnitudes and directions of the principal stresses are compared to the geologic features of the different areas of measurement. The in situ stresses are consistent in orientation with the stress direction inferred from the earthquake focal-plane solutions and existing joint patterns but inconsistent with stress directions likely to have produced the Rangely anticline. ?? 1972.

  6. Absolute measurement of the 242Pu neutron-capture cross section

    DOE PAGES

    Buckner, M. Q.; Wu, C. Y.; Henderson, R. A.; ...

    2016-04-21

    Here, the absolute neutron-capture cross section of 242Pu was measured at the Los Alamos Neutron Science Center using the Detector for Advanced Neutron-Capture Experiments array along with a compact parallel-plate avalanche counter for fission-fragment detection. The first direct measurement of the 242Pu(n,γ) cross section was made over the incident neutron energy range from thermal to ≈ 6 keV, and the absolute scale of the (n,γ) cross section was set according to the known 239Pu(n,f) resonance at E n,R = 7.83 eV. This was accomplished by adding a small quantity of 239Pu to the 242Pu sample. The relative scale of themore » cross section, with a range of four orders of magnitude, was determined for incident neutron energies from thermal to ≈ 40 keV. Our data, in general, are in agreement with previous measurements and those reported in ENDF/B-VII.1; the 242Pu(n,γ) cross section at the E n,R = 2.68 eV resonance is within 2.4% of the evaluated value. However, discrepancies exist at higher energies; our data are ≈30% lower than the evaluated data at E n ≈ 1 keV and are approximately 2σ away from the previous measurement at E n ≈ 20 keV.« less

  7. First absolute wind measurements in the middle atmosphere of Mars

    NASA Astrophysics Data System (ADS)

    Lellouch, Emmanuel; Goldstein, Jeffrey J.; Bougher, Stephen W.; Paubert, Gabriel; Rosenqvist, Jan

    1991-12-01

    The first absolute wind measurements in the middle atmosphere of Mars (40-70 km) were obtained from Doppler shifts in the J = 2-1 CO transition at 230.538 GHz. During the 1988 opposition, this line was observed at 100 kHz resolution with the IRAM 30 m telescope. The 12-arcsec FWHM beam of the facility allowed spatial resolution of the Martian disk (23.8 arcsec). The high S/N of the data allowed measurement of winds with a 1-sigma absolute line-of-sight accuracy of 20 m/s. The measurements, performed during southern summer solstice, stress the Southern Hemisphere and clearly indicate a global easterlies flow. If modeled by a broad easterly jet with a maximum centered at 20 S, and extending 80 deg in latitude, the jet core velocity is found to have a chi-sq minimum at 160 m/s, generally consistent with predictions for broad summer easterly jets near 50 km as proposed by theoretical models. If the flow is modeled instead by a planet-wide solid rotator zonal flow which is restricted to the Southern Hemisphere or equatorial regions, the velocity of the easterlies is nearly the same. These wind measurements, together with the temperature measurements of Deming et al. (1986), provide the first experimental rough picture of the middle atmosphere circulation of Mars, in general agreement with the Jaquin axisymmetric middle atmosphere model and the current Mars GCM model of Pollack et al. (1990).

  8. Precise and absolute measurements of complex third-order optical susceptibility

    NASA Astrophysics Data System (ADS)

    Santran, Stephane; Canioni, Lionel; Cardinal, Thierry; Fargin, Evelyne; Le Flem, Gilles; Rouyer, Claude; Sarger, Laurent

    2000-11-01

    We present precise and absolute measurements of full complex third order optical susceptibility on different fused silica and original glasses composed of tellurium, titanium, niobium erbium. These materials are designed to be the key point for applications ranging form high power laser systems to optoelectronics, their nonlinear index of refraction is a major property and thus must be accurately known. Due to the accuracy and sensitivity of our technique, we have been able to find a large dispersion (more than 30%) of the non linear index of fused silica glasses as a function of their processing mode. On the other hand, measurements on tellurium glasses have shown very strong nonlinearities (40 times higher than fused silica), to be linked to the configurations of their cations and anions. Although the titanium and niobium glasses are less nonlinear, they can be promising matrices for addition of luminescent entities like erbium leading to very interesting laser amplification materials. The experimental set-up is a collinear pump-probe (orthogonally polarized) experiment using transient absorption technique. It is built with around a 100 femtosecond laser oscillator. A fast oscillating delay between the pump and the probe allows us to measure the electronic nonlinearity in quasi real-time. This experiment has the following specifications: an absolute measurement accuracy below 10% mainly due to the laser parameters characterization, a relative measurement accuracy of 1% and a resolution less than 5.10-24m2/V2(50 times less than fused silica).

  9. Fully distributed absolute blood flow velocity measurement for middle cerebral arteries using Doppler optical coherence tomography

    PubMed Central

    Qi, Li; Zhu, Jiang; Hancock, Aneeka M.; Dai, Cuixia; Zhang, Xuping; Frostig, Ron D.; Chen, Zhongping

    2016-01-01

    Doppler optical coherence tomography (DOCT) is considered one of the most promising functional imaging modalities for neuro biology research and has demonstrated the ability to quantify cerebral blood flow velocity at a high accuracy. However, the measurement of total absolute blood flow velocity (BFV) of major cerebral arteries is still a difficult problem since it is related to vessel geometry. In this paper, we present a volumetric vessel reconstruction approach that is capable of measuring the absolute BFV distributed along the entire middle cerebral artery (MCA) within a large field-of-view. The Doppler angle at each point of the MCA, representing the vessel geometry, is derived analytically by localizing the artery from pure DOCT images through vessel segmentation and skeletonization. Our approach could achieve automatic quantification of the fully distributed absolute BFV across different vessel branches. Experiments on rodents using swept-source optical coherence tomography showed that our approach was able to reveal the consequences of permanent MCA occlusion with absolute BFV measurement. PMID:26977365

  10. Fully distributed absolute blood flow velocity measurement for middle cerebral arteries using Doppler optical coherence tomography.

    PubMed

    Qi, Li; Zhu, Jiang; Hancock, Aneeka M; Dai, Cuixia; Zhang, Xuping; Frostig, Ron D; Chen, Zhongping

    2016-02-01

    Doppler optical coherence tomography (DOCT) is considered one of the most promising functional imaging modalities for neuro biology research and has demonstrated the ability to quantify cerebral blood flow velocity at a high accuracy. However, the measurement of total absolute blood flow velocity (BFV) of major cerebral arteries is still a difficult problem since it is related to vessel geometry. In this paper, we present a volumetric vessel reconstruction approach that is capable of measuring the absolute BFV distributed along the entire middle cerebral artery (MCA) within a large field-of-view. The Doppler angle at each point of the MCA, representing the vessel geometry, is derived analytically by localizing the artery from pure DOCT images through vessel segmentation and skeletonization. Our approach could achieve automatic quantification of the fully distributed absolute BFV across different vessel branches. Experiments on rodents using swept-source optical coherence tomography showed that our approach was able to reveal the consequences of permanent MCA occlusion with absolute BFV measurement.

  11. Airborne Solar Radiant Flux Measurements During ACE-2

    NASA Technical Reports Server (NTRS)

    Bergstrom, Robert W.; Russell, Philip B.; Jonsson, Haflidi

    2000-01-01

    Aerosol effects on atmospheric radiative fluxes provide a forcing function that can change the climate in potentially significant ways. This aerosol radiative forcing is a major source of uncertainty in understanding the climate change of the past century and predicting future climate. To help reduce this uncertainty, the 1996 Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) and the 1997 Aerosol Characterization Experiment (ACE-2) measured the properties and radiative effects of aerosols over the Atlantic Ocean. In the ACE 2 program the solar radiant fluxes were measured on the Pelican aircraft and the UK Met Office C130. This poster will show results from the measurements for the aerosol effects during the clear column days. We will compare the results with calculations of the radiant fluxes.

  12. Real-Time and Meter-Scale Absolute Distance Measurement by Frequency-Comb-Referenced Multi-Wavelength Interferometry

    PubMed Central

    Tan, Lilong; Yan, Shuhua

    2018-01-01

    We report on a frequency-comb-referenced absolute interferometer which instantly measures long distance by integrating multi-wavelength interferometry with direct synthetic wavelength interferometry. The reported interferometer utilizes four different wavelengths, simultaneously calibrated to the frequency comb of a femtosecond laser, to implement subwavelength distance measurement, while direct synthetic wavelength interferometry is elaborately introduced by launching a fifth wavelength to extend a non-ambiguous range for meter-scale measurement. A linearity test performed comparatively with a He–Ne laser interferometer shows a residual error of less than 70.8 nm in peak-to-valley over a 3 m distance, and a 10 h distance comparison is demonstrated to gain fractional deviations of ~3 × 10−8 versus 3 m distance. Test results reveal that the presented absolute interferometer enables precise, stable, and long-term distance measurements and facilitates absolute positioning applications such as large-scale manufacturing and space missions. PMID:29414897

  13. Constraints on the neutrino flux in NOvA using the near detector data

    DOE PAGES

    Maan, Kuldeep K.

    2016-12-19

    NOvA, a long-baseline neutrino oscillation experiment at Fermilab, is designed to measure electron-neutrino appearance and muon-neutrino disappearance in the NuMI beam. NOvA comprises of two finely segmented liquid scintillator detectors at 14 mrad off-axis in the NuMI beam. An accurate prediction of the neutrino flux is needed for precision oscillation and cross-section measurements. Data from the hadron-production experiments and, importantly, from the NOvA Near Detector provide powerful constraints on the muon-neutrino and electron-neutrino fluxes. In particular, the measurement of the neutrino-electron elastic scattering provides an in situ constraint on the absolute flux. Lastly, this poster presents the data-driven predictions ofmore » the NOvA muonneutrino and electron-neutrino flux, and outlines future improvements in the flux determination.« less

  14. Measurement of a surface heat flux and temperature

    NASA Astrophysics Data System (ADS)

    Davis, R. M.; Antoine, G. J.; Diller, T. E.; Wicks, A. L.

    1994-04-01

    The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured heat flux q is proportional to the temperature difference across the resistance layer q= k(sub g)/delta(sub g) x (t(sub 1) - T(sub 2)), where k(sub g) is the thermal conductivity and delta (sub g) is the thickness of the thermal resistance layer. Because the gages are sputter coated directly onto the surface, their total thickness is less than 2 micrometers, which is two orders of magnitude thinner than previous gages. The resulting temperature difference across the thermal resistance layer (delta is less than 1 micrometer) is very small even at high heat fluxes. To generate a measurable signal many thermocouple pairs are put in series to form a differential thermopile. The combination of series thermocouple junctions and thin-film design creates a gage with very attractive characteristics. It is not only physically non-intrusive to the flow, but also causes minimal disruption of the surface temperature. Because it is so thin, the response time is less than 20 microsec. Consequently, the frequency response is flat from 0 to over 50 kHz. Moreover, the signal of the Heat Flux Microsensor is directly proportional to the heat flux. Therefore, it can easily be used in both steady and transient flows, and it measures both the steady and unsteady components of the surface heat flux. A version of the Heat Flux Microsensor has been developed to meet the harsh demands of combustion environments. These gages use platinum and platinum-10 percent rhodium as the thermoelectric materials. The thermal resistance layer is silicon monoxide and a protective coating of Al2O3 is deposited on top of the sensor. The

  15. Measurement of a surface heat flux and temperature

    NASA Technical Reports Server (NTRS)

    Davis, R. M.; Antoine, G. J.; Diller, T. E.; Wicks, A. L.

    1994-01-01

    The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured heat flux q is proportional to the temperature difference across the resistance layer q= k(sub g)/delta(sub g) x (t(sub 1) - T(sub 2)), where k(sub g) is the thermal conductivity and delta (sub g) is the thickness of the thermal resistance layer. Because the gages are sputter coated directly onto the surface, their total thickness is less than 2 micrometers, which is two orders of magnitude thinner than previous gages. The resulting temperature difference across the thermal resistance layer (delta is less than 1 micrometer) is very small even at high heat fluxes. To generate a measurable signal many thermocouple pairs are put in series to form a differential thermopile. The combination of series thermocouple junctions and thin-film design creates a gage with very attractive characteristics. It is not only physically non-intrusive to the flow, but also causes minimal disruption of the surface temperature. Because it is so thin, the response time is less than 20 microsec. Consequently, the frequency response is flat from 0 to over 50 kHz. Moreover, the signal of the Heat Flux Microsensor is directly proportional to the heat flux. Therefore, it can easily be used in both steady and transient flows, and it measures both the steady and unsteady components of the surface heat flux. A version of the Heat Flux Microsensor has been developed to meet the harsh demands of combustion environments. These gages use platinum and platinum-10 percent rhodium as the thermoelectric materials. The thermal resistance layer is silicon monoxide and a protective coating of Al2O3 is deposited on top of the sensor. The

  16. New design and facilities for the International Database for Absolute Gravity Measurements (AGrav): A support for the Establishment of a new Global Absolute Gravity Reference System

    NASA Astrophysics Data System (ADS)

    Wziontek, Hartmut; Falk, Reinhard; Bonvalot, Sylvain; Rülke, Axel

    2017-04-01

    After about 10 years of successful joint operation by BGI and BKG, the International Database for Absolute Gravity Measurements "AGrav" (see references hereafter) was under a major revision. The outdated web interface was replaced by a responsive, high level web application framework based on Python and built on top of Pyramid. Functionality was added, like interactive time series plots or a report generator and the interactive map-based station overview was updated completely, comprising now clustering and the classification of stations. Furthermore, the database backend was migrated to PostgreSQL for better support of the application framework and long-term availability. As comparisons of absolute gravimeters (AG) become essential to realize a precise and uniform gravity standard, the database was extended to document the results on international and regional level, including those performed at monitoring stations equipped with SGs. By this it will be possible to link different AGs and to trace their equivalence back to the key comparisons under the auspices of International Committee for Weights and Measures (CIPM) as the best metrological realization of the absolute gravity standard. In this way the new AGrav database accommodates the demands of the new Global Absolute Gravity Reference System as recommended by the IAG Resolution No. 2 adopted in Prague 2015. The new database will be presented with focus on the new user interface and new functionality, calling all institutions involved in absolute gravimetry to participate and contribute with their information to built up a most complete picture of high precision absolute gravimetry and improve its visibility. A Digital Object Identifier (DOI) will be provided by BGI to contributors to give a better traceability and facilitate the referencing of their gravity surveys. Links and references: BGI mirror site : http://bgi.obs-mip.fr/data-products/Gravity-Databases/Absolute-Gravity-data/ BKG mirror site: http

  17. Grasland Stable Isotope Flux Measurements: Three Isotopomers of Carbon Dioxide Measured by QCL Spectroscopy

    NASA Astrophysics Data System (ADS)

    Zeeman, M. J.; Tuzson, B.; Eugster, W.; Werner, R. A.; Buchmann, N.; Emmenegger, L.

    2007-12-01

    To improve our understanding of greenhouse gas dynamics of managed ecosystems such as grasslands, we not only need to investigate the effects of management (e.g., grass cuts) and weather events (e.g., rainy days) on carbon dioxide fluxes, but also need to increase the time resolution of our measurements. Thus, for the first time, we assessed respiration and assimilation fluxes with high time resolution (5Hz) stable isotope measurements at an intensively managed farmland in Switzerland (Chamau, 400m ASL). Two different methods were used to quantify fluxes of carbon dioxide and associated fluxes of stable carbon isotopes: (1) the flux gradient method, and (2) the eddy covariance method. During a week long intensive measurement campaign, we (1) measured mixing ratios of carbon dioxide isotopomers (12C16O2, 12C16O18O, 13C16O2) with a Quantum Cascade Laser (QCL, Aerodyne Inc.) spectroscope and (2) collected air samples for isotope analyses (13C/12C) and (18O/16O) of carbon dioxide by Isotope Ratio Mass Spectrometry (IRMS, Finnigan) every two hours, concurrently along a height profile (z = 0.05; 0.10; 0.31; 2.15m). In the following week, the QCL setup was used for closed-path eddy covariance flux measurement of the carbon dioxide isotopomers, with the air inlet located next to an open-path Infra Red Gas Analyzers (IRGA, LiCor 7500) used simultaneously for carbon dioxide measurements. During this second week, an area of grass inside the footprint was cut and harvested after several days. The first results of in-field continuous QCL measurements of carbon dioxide mixing ratios and their stable isotopic ratios show good agreement with IRGA measurements and isotope analysis of flask samples by IRMS. Thus, QCL spectroscopy is a very promising tool for stable isotope flux investigations.

  18. Accurate Measurement of Absolute Terahertz Power Using Broadband Calorimeter

    NASA Astrophysics Data System (ADS)

    Iida, Hitoshi; Kinoshita, Moto; Amemiya, Kuniaki

    2018-03-01

    This paper presents a highly sensitive terahertz (THz) calorimeter developed using a magnetically loaded epoxy as a broadband absorber. The reflection loss of the absorber, which has a pyramidally textured surface, is less than 0.04, as determined using a THz time-domain spectrometer and a vector network analyzer. The THz calorimeter successfully enabled the measurement of the absolute THz power from a photomixer at microwatt levels at room temperature. The measurement uncertainties at a 95% confidence level were 6.2% for 13 μW at 300 GHz and 5.6% for 1.5 μW at 1 THz, respectively. Details of the evaluation and uncertainty analyses are also presented.

  19. Accuracy of Zero-Heat-Flux Cutaneous Temperature in Intensive Care Adults.

    PubMed

    Dahyot-Fizelier, Claire; Lamarche, Solène; Kerforne, Thomas; Bénard, Thierry; Giraud, Benoit; Bellier, Rémy; Carise, Elsa; Frasca, Denis; Mimoz, Olivier

    2017-07-01

    To compare accuracy of a continuous noninvasive cutaneous temperature using zero-heat-flux method to esophageal temperature and arterial temperature. Prospective study. ICU and NeuroICU, University Hospital. Fifty-two ICU patients over a 4-month period who required continuous temperature monitoring were included in the study, after informed consent. All patients had esophageal temperature probe and a noninvasive cutaneous device to monitor their core temperature continuously. In seven patients who required cardiac output monitoring, continuous iliac arterial temperature was collected. Simultaneous core temperatures were recorded from 1 to 5 days. Comparison to the esophageal temperature, considered as the reference in this study, used the Bland and Altman method with adjustment for multiple measurements per patient. The esophageal temperature ranged from 33°C to 39.7°C, 61,298 pairs of temperature using zero-heat-flux and esophageal temperature were collected and 1,850 triple of temperature using zero-heat-flux, esophageal temperature, and arterial temperature. Bias and limits of agreement for temperature using zero-heat-flux were 0.19°C ± 0.53°C compared with esophageal temperature with an absolute difference of temperature pairs equal to or lower than 0.5°C of 92.6% (95% CI, 91.9-93.4%) of cases and equal to or lower than 1°C for 99.9% (95% CI, 99.7-100.0%) of cases. Compared with arterial temperature, bias and limits of agreement were -0.00°C ± 0.36°C with an absolute difference of temperature pairs equal to or lower than 0.5°C of 99.8% (95% CI, 95.3-100%) of cases. All absolute difference of temperature pairs between temperature using zero-heat-flux and arterial temperature and between arterial temperature and esophageal temperature were equal to or lower than 1°C. No local or systemic serious complication was observed. These results suggest a comparable reliability of the cutaneous sensor using the zero-heat-flux method compared with esophageal or

  20. Distributed Sensible Heat Flux Measurements for Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Huwald, H.; Brauchli, T.; Lehning, M.; Higgins, C. W.

    2015-12-01

    The sensible heat flux component of the surface energy balance is typically computed using eddy covariance or two point profile measurements while alternative approaches such as the flux variance method based on convective scaling has been much less explored and applied. Flux variance (FV) certainly has a few limitations and constraints but may be an interesting and competitive method in low-cost and power limited wireless sensor networks (WSN) with the advantage of providing spatio-temporal sensible heat flux over the domain of the network. In a first step, parameters such as sampling frequency, sensor response time, and averaging interval are investigated. Then we explore the applicability and the potential of the FV method for use in WSN in a field experiment. Low-cost sensor systems are tested and compared against reference instruments (3D sonic anemometers) to evaluate the performance and limitations of the sensors as well as the method with respect to the standard calculations. Comparison experiments were carried out at several sites to gauge the flux measurements over different surface types (gravel, grass, water) from the low-cost systems. This study should also serve as an example of spatially distributed sensible heat flux measurements.

  1. Cosmological flux noise and measured noise power spectra in SQUIDs

    PubMed Central

    Beck, Christian

    2016-01-01

    The understanding of the origin of 1/f magnetic flux noise commonly observed in superconducting devices such as SQUIDs and qubits is still a major unsolved puzzle. Here we discuss the possibility that a significant part of the observed low-frequency flux noise measured in these devices is ultimately seeded by cosmological fluctuations. We consider a theory where a primordial flux noise field left over in unchanged form from an early inflationary or quantum gravity epoch of the universe intrinsically influences the phase difference in SQUIDs and qubits. The perturbation seeds generated by this field can explain in a quantitatively correct way the form and amplitude of measured low-frequency flux noise spectra in SQUID devices if one takes as a source of fluctuations the primordial power spectrum of curvature fluctuations as measured by the Planck collaboration. Our theoretical predictions are in excellent agreement with recent low-frequency flux noise measurements of various experimental groups. Magnetic flux noise, so far mainly considered as a nuisance for electronic devices, may thus contain valuable information about fluctuation spectra in the very early universe. PMID:27320418

  2. Cosmological flux noise and measured noise power spectra in SQUIDs.

    PubMed

    Beck, Christian

    2016-06-20

    The understanding of the origin of 1/f magnetic flux noise commonly observed in superconducting devices such as SQUIDs and qubits is still a major unsolved puzzle. Here we discuss the possibility that a significant part of the observed low-frequency flux noise measured in these devices is ultimately seeded by cosmological fluctuations. We consider a theory where a primordial flux noise field left over in unchanged form from an early inflationary or quantum gravity epoch of the universe intrinsically influences the phase difference in SQUIDs and qubits. The perturbation seeds generated by this field can explain in a quantitatively correct way the form and amplitude of measured low-frequency flux noise spectra in SQUID devices if one takes as a source of fluctuations the primordial power spectrum of curvature fluctuations as measured by the Planck collaboration. Our theoretical predictions are in excellent agreement with recent low-frequency flux noise measurements of various experimental groups. Magnetic flux noise, so far mainly considered as a nuisance for electronic devices, may thus contain valuable information about fluctuation spectra in the very early universe.

  3. Estimating Total Heliospheric Magnetic Flux from Single-Point in Situ Measurements

    NASA Technical Reports Server (NTRS)

    Owens, M. J.; Arge, C. N.; Crooker, N. U.; Schwardron, N. A.; Horbury, T. S.

    2008-01-01

    A fraction of the total photospheric magnetic flux opens to the heliosphere to form the interplanetary magnetic field carried by the solar wind. While this open flux is critical to our understanding of the generation and evolution of the solar magnetic field, direct measurements are generally limited to single-point measurements taken in situ by heliospheric spacecraft. An observed latitude invariance in the radial component of the magnetic field suggests that extrapolation from such single-point measurements to total heliospheric magnetic flux is possible. In this study we test this assumption using estimates of total heliospheric flux from well-separated heliospheric spacecraft and conclude that single-point measurements are indeed adequate proxies for the total heliospheric magnetic flux, though care must be taken when comparing flux estimates from data collected at different heliocentric distances.

  4. Quantitative method for measuring heat flux emitted from a cryogenic object

    DOEpatents

    Duncan, Robert V.

    1993-01-01

    The present invention is a quantitative method for measuring the total heat flux, and of deriving the total power dissipation, of a heat-fluxing object which includes the steps of placing an electrical noise-emitting heat-fluxing object in a liquid helium bath and measuring the superfluid transition temperature of the bath. The temperature of the liquid helium bath is thereafter reduced until some measurable parameter, such as the electrical noise, exhibited by the heat-fluxing object or a temperature-dependent resistive thin film in intimate contact with the heat-fluxing object, becomes greatly reduced. The temperature of the liquid helum bath is measured at this point. The difference between the superfluid transition temperature of the liquid helium bath surrounding the heat-fluxing object, and the temperature of the liquid helium bath when the electrical noise emitted by the heat-fluxing object becomes greatly reduced, is determined. The total heat flux from the heat-fluxing object is determined as a function of this difference between these temperatures. In certain applications, the technique can be used to optimize thermal design parameters of cryogenic electronics, for example, Josephson junction and infra-red sensing devices.

  5. Quantitative method for measuring heat flux emitted from a cryogenic object

    DOEpatents

    Duncan, R.V.

    1993-03-16

    The present invention is a quantitative method for measuring the total heat flux, and of deriving the total power dissipation, of a heat-fluxing object which includes the steps of placing an electrical noise-emitting heat-fluxing object in a liquid helium bath and measuring the superfluid transition temperature of the bath. The temperature of the liquid helium bath is thereafter reduced until some measurable parameter, such as the electrical noise, exhibited by the heat-fluxing object or a temperature-dependent resistive thin film in intimate contact with the heat-fluxing object, becomes greatly reduced. The temperature of the liquid helum bath is measured at this point. The difference between the superfluid transition temperature of the liquid helium bath surrounding the heat-fluxing object, and the temperature of the liquid helium bath when the electrical noise emitted by the heat-fluxing object becomes greatly reduced, is determined. The total heat flux from the heat-fluxing object is determined as a function of this difference between these temperatures. In certain applications, the technique can be used to optimize thermal design parameters of cryogenic electronics, for example, Josephson junction and infrared sensing devices.

  6. SIERRA-Flux: Measuring Regional Surface Fluxes of Carbon Dioxide, Methane, and Water Vapor from an Unmanned Aircraft System

    NASA Technical Reports Server (NTRS)

    Fladeland; Yates, Emma Louise; Bui, Thaopaul Van; Dean-Day, Jonathan; Kolyer, Richard

    2011-01-01

    The Eddy-Covariance Method for quantifying surface-atmosphere fluxes is a foundational technique for measuring net ecosystem exchange and validating regional-to-global carbon cycle models. While towers or ships are the most frequent platform for measuring surface-atmosphere exchange, experiments using aircraft for flux measurements have yielded contributions to several large-scale studies including BOREAS, SMACEX, RECAB by providing local-to-regional coverage beyond towers. The low-altitude flight requirements make airborne flux measurements particularly dangerous and well suited for unmanned aircraft.

  7. An absolute scale for measuring the utility of money

    NASA Astrophysics Data System (ADS)

    Thomas, P. J.

    2010-07-01

    Measurement of the utility of money is essential in the insurance industry, for prioritising public spending schemes and for the evaluation of decisions on protection systems in high-hazard industries. Up to this time, however, there has been no universally agreed measure for the utility of money, with many utility functions being in common use. In this paper, we shall derive a single family of utility functions, which have risk-aversion as the only free parameter. The fact that they return a utility of zero at their low, reference datum, either the utility of no money or of one unit of money, irrespective of the value of risk-aversion used, qualifies them to be regarded as absolute scales for the utility of money. Evidence of validation for the concept will be offered based on inferential measurements of risk-aversion, using diverse measurement data.

  8. First Absolutely Calibrated Localized Measurements of Ion Velocity in the MST in Locked and Rotating Plasmas

    NASA Astrophysics Data System (ADS)

    Baltzer, M.; Craig, D.; den Hartog, D. J.; Nornberg, M. D.; Munaretto, S.

    2015-11-01

    An Ion Doppler Spectrometer (IDS) is used on MST for high time-resolution passive and active measurements of impurity ion emission. Absolutely calibrated measurements of flow are difficult because the spectrometer records data within 0.3 nm of the C+5 line of interest, and commercial calibration lamps do not produce lines in this narrow range . A novel optical system was designed to absolutely calibrate the IDS. The device uses an UV LED to produce a broad emission curve in the desired region. A Fabry-Perot etalon filters this light, cutting transmittance peaks into the pattern of the LED emission. An optical train of fused silica lenses focuses the light into the IDS with f/4. A holographic diffuser blurs the light cone to increase homogeneity. Using this light source, the absolute Doppler shift of ion emissions can be measured in MST plasmas. In combination with charge exchange recombination spectroscopy, localized ion velocities can now be measured. Previously, a time-averaged measurement along the chord bisecting the poloidal plane was used to calibrate the IDS; the quality of these central chord calibrations can be characterized with our absolute calibration. Calibration errors may also be quantified and minimized by optimizing the curve-fitting process. Preliminary measurements of toroidal velocity in locked and rotating plasmas will be shown. This work has been supported by the US DOE.

  9. Micrometeorological flux measurements at a coastal site

    NASA Astrophysics Data System (ADS)

    Song, Guozheng; Meixner, Franz X.; Bruse, Michael; Mamtimin, Buhalqem

    2014-05-01

    The eddy covariance (EC) technique is the only direct measurement of the momentum, heat, and trace gas (e.g. water vapor, CO2 and ozone) fluxes. The measurements are expected to be most accurate over flat terrain where there is an extended homogenous surface upwind from the tower, and when the environmental conditions are steady. Additionally, the one dimensional approach assumes that vertical turbulent exchange is the dominant flux, whereas advective influences should be negligible. The application of EC method under non-ideal conditions, for example in complex terrain, has yet to be fully explored. To explore the possibilities and limitations of EC technique under non-ideal conditions, an EC system was set up at Selles beach, Crete, Greece (35.33°N, 25.71°E) in the beginning of July 2012. The dominant wind direction was west, parallel to the coast. The EC system consisted of a sonic anemometer (CSAT3 Campbell Scientific), an infrared open-path CO2/H2O gas analyzer (LI-7500, Li-COR Biosciences) and a fast chemiluminescence ozone analyzer (enviscope GmbH). All the signals of these fast response instruments were sampled at 10 Hz and the measurement height was 3 m. Besides, another gradient system was setup. Air temperature, relative humidity (HYGROMER MP 103 A), and wind speed (WMT700 Vaisala) were measured every 10 seconds at 3 heights (0.7, 1.45, 3 m). Air intakes were set up at 0.7m and 3m. A pump drew the air through a flow system and a telflon valve alternately switched between the two heights every 30 seconds. H2O, CO2 (LI-840A, Li-COR Biosciences) and ozone mixing ratio s (model 205, 2BTechnologies) were measured every 10 seconds. Momentum, heat, CO2 and ozone fluxes were evaluated by both EC and gradient technique. For the calculation of turbulent fluxes, TK3 algorithm (Department of Micrometeorology, University Bayreuth, Germany) was applied. We will present the measured fluxes of the two systems and assess the data quality under such non-ideal condition.

  10. First flux surface measurements on W7-X

    NASA Astrophysics Data System (ADS)

    Pedersen, Thomas Sunn; Otte, Matthias; Biedermann, Christoph; Bozhenkov, Sergey; Braeuer, Torsten; Lazerson, Samuel; W7-X Team

    2015-11-01

    Wendelstein 7-X is rapidly approaching first plasma operation. The full operational B-field of 2.5 T has been reached using the 70 superconducting coils. The first flux surface measurements have recently been successfully performed. This talk will describe the W7-X flux surface measurement system, and show and analyze the first results from this diagnostic, which, at the time of writing this abstract, can be summarized as follows: Confirmation of the existence of nested, closed flux surfaces, first measurements of iota, and detection of the expected internal 5/6 island chain of the OP1.1 configuration. The data obtained so far agree with expectations, and provide a first confirmation of the accuracy of the coil geometry and assembly, as well as diagnostic installation. They also confirm that, with respect to the magnetic topology, plasma operation can start. Plans for, and potentially first results of, measurements of any remnant field errors, will be reported separately at this meeting.

  11. Velocity space resolved absolute measurement of fast ion losses induced by a tearing mode in the ASDEX Upgrade tokamak

    NASA Astrophysics Data System (ADS)

    Galdon-Quiroga, J.; Garcia-Munoz, M.; Sanchis-Sanchez, L.; Mantsinen, M.; Fietz, S.; Igochine, V.; Maraschek, M.; Rodriguez-Ramos, M.; Sieglin, B.; Snicker, A.; Tardini, G.; Vezinet, D.; Weiland, M.; Eriksson, L. G.; The ASDEX Upgrade Team; The EUROfusion MST1 Team

    2018-03-01

    Absolute flux of fast ion losses induced by tearing modes have been measured by means of fast ion loss detectors (FILD) for the first time in RF heated plasmas in the ASDEX Upgrade tokamak. Up to 30 MW m-2 of fast ion losses are measured by FILD at 5 cm from the separatrix, consistent with infra-red camera measurements, with energies in the range of 250-500 keV and pitch angles corresponding to large trapped orbits. A resonant interaction between the fast ions in the high energy tail of the ICRF distribution and a m/n  =  5/4 tearing mode leads to enhanced fast ion losses. Around 9.3 +/- 0.7 % of the fast ion losses are found to be coherent with the mode and scale linearly with its amplitude, indicating the convective nature of the transport mechanism. Simulations have been carried out to estimate the contribution of the prompt losses. A good agreement is found between the simulated and the measured velocity space of the losses. The velocity space resonances that may be responsible for the enhanced fast ion losses are identified.

  12. Passive flux meter measurement of water and nutrient flux in saturated porous media: bench-scale laboratory tests.

    PubMed

    Cho, Jaehyun; Annable, Michael D; Jawitz, James W; Hatfield, Kirk

    2007-01-01

    The passive nutrient flux meter (PNFM) is introduced for simultaneous measurement of both water and nutrient flux through saturated porous media. The PNFM comprises a porous sorbent pre-equilibrated with a suite of alcohol tracers, which have different partitioning coefficients. Water flux was estimated based on the loss of loaded resident tracers during deployment, while nutrient flux was quantified based on the nutrient solute mass captured on the sorbent. An anionic resin, Lewatit 6328 A, was used as a permeable sorbent and phosphate (PO4(3-)) was the nutrient studied. The phosphate sorption capacity of the resin was measured in batch equilibration tests as 56 mg PO4(3-) g(-1), which was determined to be adequate capacity to retain PO4(3-) loads intercepted over typical PNFM deployment periods in most natural systems. The PNFM design was validated with bench-scale laboratory tests for a range of 9.8 to 28.3 cm d(-1) Darcy velocities and 6 to 43 h deployment durations. Nutrient and water fluxes measured by the PNFM averaged within 6 and 12% of the applied values, respectively, indicating that the PNFM shows promise as a tool for simultaneous measurement of water and nutrient fluxes.

  13. Interplanetary magnetic flux - Measurement and balance

    NASA Technical Reports Server (NTRS)

    Mccomas, D. J.; Gosling, J. T.; Phillips, J. L.

    1992-01-01

    A new method for determining the approximate amount of magnetic flux in various solar wind structures in the ecliptic (and solar rotation) plane is developed using single-spacecraft measurements in interplanetary space and making certain simplifying assumptions. The method removes the effect of solar wind velocity variations and can be applied to specific, limited-extent solar wind structures as well as to long-term variations. Over the 18-month interval studied, the ecliptic plane flux of coronal mass ejections was determined to be about 4 times greater than that of HFDs.

  14. Eddy covariance flux measurements of gaseous elemental mercury using cavity ring-down spectroscopy.

    PubMed

    Pierce, Ashley M; Moore, Christopher W; Wohlfahrt, Georg; Hörtnagl, Lukas; Kljun, Natascha; Obrist, Daniel

    2015-02-03

    A newly developed pulsed cavity ring-down spectroscopy (CRDS) system for measuring atmospheric gaseous elemental mercury (GEM) concentrations at high temporal resolution (25 Hz) was used to successfully conduct the first eddy covariance (EC) flux measurements of GEM. GEM is the main gaseous atmospheric form, and quantification of bidirectional exchange between the Earth's surface and the atmosphere is important because gas exchange is important on a global scale. For example, surface GEM emissions from natural sources, legacy emissions, and re-emission of previously deposited anthropogenic pollution may exceed direct primary anthropogenic emissions. Using the EC technique for flux measurements requires subsecond measurements, which so far has not been feasible because of the slow time response of available instrumentation. The CRDS system measured GEM fluxes, which were compared to fluxes measured with the modified Bowen ratio (MBR) and a dynamic flux chamber (DFC). Measurements took place near Reno, NV, in September and October 2012 encompassing natural, low-mercury (Hg) background soils and Hg-enriched soils. During nine days of measurements with deployment of Hg-enriched soil in boxes within 60 m upwind of the EC tower, the covariance of GEM concentration and vertical wind speed was measured, showing that EC fluxes over an Hg-enriched area were detectable. During three separate days of flux measurements over background soils (without Hg-enriched soils), no covariance was detected, indicating fluxes below the detection limit. When fluxes were measurable, they strongly correlated with wind direction; the highest fluxes occurred when winds originated from the Hg-enriched area. Comparisons among the three methods showed good agreement in direction (e.g., emission or deposition) and magnitude, especially when measured fluxes originated within the Hg-enriched soil area. EC fluxes averaged 849 ng m(-2) h(-1), compared to DFC fluxes of 1105 ng m(-2) h(-1) and MBR fluxes

  15. Measurement and simulation of thermal neutron flux distribution in the RTP core

    NASA Astrophysics Data System (ADS)

    Rabir, Mohamad Hairie B.; Jalal Bayar, Abi Muttaqin B.; Hamzah, Na'im Syauqi B.; Mustafa, Muhammad Khairul Ariff B.; Karim, Julia Bt. Abdul; Zin, Muhammad Rawi B. Mohamed; Ismail, Yahya B.; Hussain, Mohd Huzair B.; Mat Husin, Mat Zin B.; Dan, Roslan B. Md; Ismail, Ahmad Razali B.; Husain, Nurfazila Bt.; Jalil Khan, Zareen Khan B. Abdul; Yakin, Shaiful Rizaide B. Mohd; Saad, Mohamad Fauzi B.; Masood, Zarina Bt.

    2018-01-01

    The in-core thermal neutron flux distribution was determined using measurement and simulation methods for the Malaysian’s PUSPATI TRIGA Reactor (RTP). In this work, online thermal neutron flux measurement using Self Powered Neutron Detector (SPND) has been performed to verify and validate the computational methods for neutron flux calculation in RTP calculations. The experimental results were used as a validation to the calculations performed with Monte Carlo code MCNP. The detail in-core neutron flux distributions were estimated using MCNP mesh tally method. The neutron flux mapping obtained revealed the heterogeneous configuration of the core. Based on the measurement and simulation, the thermal flux profile peaked at the centre of the core and gradually decreased towards the outer side of the core. The results show a good agreement (relatively) between calculation and measurement where both show the same radial thermal flux profile inside the core: MCNP model over estimation with maximum discrepancy around 20% higher compared to SPND measurement. As our model also predicts well the neutron flux distribution in the core it can be used for the characterization of the full core, that is neutron flux and spectra calculation, dose rate calculations, reaction rate calculations, etc.

  16. A new Ultra Precision Interferometer for absolute length measurements down to cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Schödel, R.; Walkov, A.; Zenker, M.; Bartl, G.; Meeß, R.; Hagedorn, D.; Gaiser, C.; Thummes, G.; Heltzel, S.

    2012-09-01

    A new Ultra Precision Interferometer (UPI) was built at Physikalisch-Technische Bundesanstalt. As its precursor, the precision interferometer, it was designed for highly precise absolute length measurements of prismatic bodies, e.g. gauge blocks, under well-defined temperature conditions and pressure, making use of phase stepping imaging interferometry. The UPI enables a number of enhanced features, e.g. it is designed for a much better lateral resolution and better temperature stability. In addition to the original concept, the UPI is equipped with an external measurement pathway (EMP) in which a prismatic body can be placed alternatively. The temperature of the EMP can be controlled in a much wider range compared to the temperature of the interferometer's main chamber. An appropriate cryostat system, a precision temperature measurement system and improved imaging interferometry were established to permit absolute length measurements down to cryogenic temperature, demonstrated for the first time ever. Results of such measurements are important for studying thermal expansion of materials from room temperature towards less than 10 K.

  17. Absolute Wavelength Calibration of the IDSII Spectrometer for Impurity Ion Velocity Measurements in the MST

    NASA Astrophysics Data System (ADS)

    Baltzer, M.; Craig, D.; den Hartog, D. J.; Nornberg, M. D.; MST Team

    2014-10-01

    The MST operates two Ion Doppler Spectrometers (IDS) for high time-resolution passive and active measurements of impurity ion emission. Absolutely calibrated measurements of flow are difficult because the spectrometers record data within 0.3 nm of the line of interest, and commercial calibration lamps do not produce lines in this narrow range . Four calibration methods were investigated. First, emission along the chord bisecting the poloidal plane was measured as it should have no time-averaged Doppler shift. Second, a calibrated CCD spectrometer and the IDSII were used to observe the same plasma from opposing sides so as to measure opposite Doppler shifts. The unshifted line is located halfway between the two opposing measurements. Third, the two fibers of the IDSI were positioned to take absolute flow measurements using opposing views. Substituting the IDSII for one of the IDSI fibers, absolute measurements of flow from the IDSI were used to calibrate the IDSII. Finally, an optical system was designed to filter an ultraviolet LED, providing a known wavelength source within the spectral range covered by the IDSII. The optical train is composed of an air-gapped etalon and fused silica lenses. The quality of calibration for each of these methods is analyzed and their results compared. Preliminary impurity ion velocity measurements are shown. This work has been supported by the US DOE and the NSF.

  18. New Measurement of the Flux of Atmospheric Muons

    NASA Astrophysics Data System (ADS)

    Boezio, M.; Carlson, P.; Francke, T.; Weber, N.; Suffert, M.; Hof, M.; Menn, W.; Simon, M.; Stephens, S. A.; Bellotti, R.; Cafagna, F.; Castellano, M.; Circella, M.; de Marzo, C.; Grimani, C.; Finetti, N.; Papini, P.; Piccardi, S.; Spillantini, P.; Ricci, M.; Casolino, M.; de Pascale, M. P.; Morselli, A.; Picozza, P.; Sparvoli, R.; Barbiellini, G.; Bravar, U.; Schiavon, P.; Vacchi, A.; Zampa, N.; Mitchell, J. W.; Ormes, J. F.; Streitmatter, R. E.; Golden, R. L.; Stochaj, S. J.

    1999-06-01

    We report a new measurement of the momentum spectra of both positive and negative muons as a function of atmospheric depth in the momentum range 0.3-2 and 0.3-40 GeV/c, respectively. The measured flux values have been compared with the spectra obtained from simulations, which were carried out to interpret the atmospheric neutrino data. We find that our data disagree with the results from the simulations. The ratio of the flux of muons derived from simulations to that measured is at largest 1.8 and varies with atmospheric depth and muon momentum.

  19. Densitometric tomography using the measurement of muon flux

    NASA Astrophysics Data System (ADS)

    Hivert, F.; Busto, J.; Brunner, J.; Salin, P.; Gaffet, S.

    2013-12-01

    The knowledge of the subsurface properties is essentially obtained by geophysical methods, e.g. seismic imaging, electric prospection or gravimetry. The present work develops a recent method to investigate the in situ density of rocks using atmospheric the muon flux measurement , its attenuation depending on the rock density and thickness. This new geophysical technique have been mainly applied in volcanology (Lesparre N., 2011) using scintillator detectors. The present project (T2DM2) aims to realize underground muons flux measurements in order to characterizing the rock massif density variations above the LSBB underground research facility in Rustrel (France). The muon flux will be measure with a new Muon telescope instrumentation using Micromegas detectors in Time Projection Chambers (TPC) configuration. The first step of the work presented considers the muon flux simulation using the Gaisser model, for the interactions between muons and atmospheric particles, and the MUSIC code (Kudryavtsev V. A., 2008) for the muons/rock interactions. The results show that the muon flux attenuation caused by density variations are enough significant to be observed until around 500 m depth and for period of time in the order of one month. Such a duration scale and depth of investigation is compatible with the duration of the water transfer processes involved within the Karst unsaturated zone where LSBB is located. Our work now concentrates on the optimization of the spatial distribution of detectors that will be deployed in future.

  20. Absolute Position of Targets Measured Through a Chamber Window Using Lidar Metrology Systems

    NASA Technical Reports Server (NTRS)

    Kubalak, David; Hadjimichael, Theodore; Ohl, Raymond; Slotwinski, Anthony; Telfer, Randal; Hayden, Joseph

    2012-01-01

    Lidar is a useful tool for taking metrology measurements without the need for physical contact with the parts under test. Lidar instruments are aimed at a target using azimuth and elevation stages, then focus a beam of coherent, frequency modulated laser energy onto the target, such as the surface of a mechanical structure. Energy from the reflected beam is mixed with an optical reference signal that travels in a fiber path internal to the instrument, and the range to the target is calculated based on the difference in the frequency of the returned and reference signals. In cases when the parts are in extreme environments, additional steps need to be taken to separate the operator and lidar from that environment. A model has been developed that accurately reduces the lidar data to an absolute position and accounts for the three media in the testbed air, fused silica, and vacuum but the approach can be adapted for any environment or material. The accuracy of laser metrology measurements depends upon knowing the parameters of the media through which the measurement beam travels. Under normal conditions, this means knowledge of the temperature, pressure, and humidity of the air in the measurement volume. In the past, chamber windows have been used to separate the measuring device from the extreme environment within the chamber and still permit optical measurement, but, so far, only relative changes have been diagnosed. The ability to make accurate measurements through a window presents a challenge as there are a number of factors to consider. In the case of the lidar, the window will increase the time-of-flight of the laser beam causing a ranging error, and refract the direction of the beam causing angular positioning errors. In addition, differences in pressure, temperature, and humidity on each side of the window will cause slight atmospheric index changes and induce deformation and a refractive index gradient within the window. Also, since the window is a

  1. Electrical Noise and the Measurement of Absolute Temperature, Boltzmann's Constant and Avogadro's Number.

    ERIC Educational Resources Information Center

    Ericson, T. J.

    1988-01-01

    Describes an apparatus capable of measuring absolute temperatures of a tungsten filament bulb up to normal running temperature and measuring Botzmann's constant to an accuracy of a few percent. Shows that electrical noise techniques are convenient to demonstrate how the concept of temperature is related to the micro- and macroscopic world. (CW)

  2. Absolute Radiation Measurements in Earth and Mars Entry Conditions

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.

    2014-01-01

    This paper reports on the measurement of radiative heating for shock heated flows which simulate conditions for Mars and Earth entries. Radiation measurements are made in NASA Ames' Electric Arc Shock Tube at velocities from 3-15 km/s in mixtures of N2/O2 and CO2/N2/Ar. The technique and limitations of the measurement are summarized in some detail. The absolute measurements will be discussed in regards to spectral features, radiative magnitude and spatiotemporal trends. Via analysis of spectra it is possible to extract properties such as electron density, and rotational, vibrational and electronic temperatures. Relaxation behind the shock is analyzed to determine how these properties relax to equilibrium and are used to validate and refine kinetic models. It is found that, for some conditions, some of these values diverge from non-equilibrium indicating a lack of similarity between the shock tube and free flight conditions. Possible reasons for this are discussed.

  3. Absolute cross-section measurements of inner-shell ionization

    NASA Astrophysics Data System (ADS)

    Schneider, Hans; Tobehn, Ingo; Ebel, Frank; Hippler, Rainer

    1994-12-01

    Cross section ratios for K- and L-shell ionization of thin silver and gold targets by positron and electron impact have been determined at projectile energies of 30 70 keV. The experimental results are confirmed by calculations in plane wave Born approximation (PWBA) which include an electron exchange term and account for the deceleration or acceleration of the incident projectile in the nuclear field of the target atom. We report first absolute cross sections for K- and L-shell ionization of silver and gold targets by lepton impact in the threshold region. We have measured the corresponding cross sections for electron (e-) impact with an electron gun and the same experimental set-up.

  4. Uncertainty of calorimeter measurements at NREL's high flux solar furnace

    NASA Astrophysics Data System (ADS)

    Bingham, C. E.

    1991-12-01

    The uncertainties of the calorimeter and concentration measurements at the High Flux Solar Furnace (HFSF) at the National Renewable Energy Laboratory (NREL) are discussed. Two calorimeter types have been used to date. One is an array of seven commercially available circular foil calorimeters (gardon or heat flux gages) for primary concentrator peak flux (up to 250 W/sq cm). The second is a cold-water calorimeter designed and built by the University of Chicago to measure the average exit power of the reflective compound parabolic secondary concentrator used at the HFSF (over 3.3 kW across a 1.6/sq cm) exit aperture, corresponding to a flux of about 2 kW/sq cm. This paper discussed the uncertainties of the calorimeter and pyrheliometer measurements and resulting concentration calculations. The measurement uncertainty analysis is performed according to the ASME/ANSI standard PTC 19.1 (1985). Random and bias errors for each portion of the measurement are analyzed. The results show that as either the power or the flux is reduced, the uncertainties increase. Another calorimeter is being designed for a new, refractive secondary which will use a refractive material to produce a higher average flux (5 kW/sq cm) than the reflective secondary. The new calorimeter will use a time derivative of the fluid temperature as a key measurement of the average power out of the secondary. A description of this calorimeter and test procedure is also presented, along with a pre-test estimate of major sources of uncertainty.

  5. Alpha absolute power measurement in panic disorder with agoraphobia patients.

    PubMed

    de Carvalho, Marcele Regine; Velasques, Bruna Brandão; Freire, Rafael C; Cagy, Maurício; Marques, Juliana Bittencourt; Teixeira, Silmar; Rangé, Bernard P; Piedade, Roberto; Ribeiro, Pedro; Nardi, Antonio Egidio; Akiskal, Hagop Souren

    2013-10-01

    Panic attacks are thought to be a result from a dysfunctional coordination of cortical and brainstem sensory information leading to heightened amygdala activity with subsequent neuroendocrine, autonomic and behavioral activation. Prefrontal areas may be responsible for inhibitory top-down control processes and alpha synchronization seems to reflect this modulation. The objective of this study was to measure frontal absolute alpha-power with qEEG in 24 subjects with panic disorder and agoraphobia (PDA) compared to 21 healthy controls. qEEG data were acquired while participants watched a computer simulation, consisting of moments classified as "high anxiety"(HAM) and "low anxiety" (LAM). qEEG data were also acquired during two rest conditions, before and after the computer simulation display. We observed a higher absolute alpha-power in controls when compared to the PDA patients while watching the computer simulation. The main finding was an interaction between the moment and group factors on frontal cortex. Our findings suggest that the decreased alpha-power in the frontal cortex for the PDA group may reflect a state of high excitability. Our results suggest a possible deficiency in top-down control processes of anxiety reflected by a low absolute alpha-power in the PDA group while watching the computer simulation and they highlight that prefrontal regions and frontal region nearby the temporal area are recruited during the exposure to anxiogenic stimuli. © 2013 Elsevier B.V. All rights reserved.

  6. Determination of collagen fibril size via absolute measurements of second-harmonic generation signals

    NASA Astrophysics Data System (ADS)

    Bancelin, Stéphane; Aimé, Carole; Gusachenko, Ivan; Kowalczuk, Laura; Latour, Gaël; Coradin, Thibaud; Schanne-Klein, Marie-Claire

    2014-09-01

    The quantification of collagen fibril size is a major issue for the investigation of pathological disorders associated with structural defects of the extracellular matrix. Second-harmonic generation microscopy is a powerful technique to characterize the macromolecular organization of collagen in unstained biological tissues. Nevertheless, due to the complex coherent building of this nonlinear optical signal, it has never been used to measure fibril diameter so far. Here we report absolute measurements of second-harmonic signals from isolated fibrils down to 30 nm diameter, via implementation of correlative second-harmonic-electron microscopy. Moreover, using analytical and numerical calculations, we demonstrate that the high sensitivity of this technique originates from the parallel alignment of collagen triple helices within fibrils and the subsequent constructive interferences of second-harmonic radiations. Finally, we use these absolute measurements as a calibration for ex vivo quantification of fibril diameter in the Descemet’s membrane of a diabetic rat cornea.

  7. How to choose methods for lake greenhouse gas flux measurements?

    NASA Astrophysics Data System (ADS)

    Bastviken, David

    2017-04-01

    Lake greenhouse gas (GHG) fluxes are increasingly recognized as important for lake ecosystems as well as for large scale carbon and GHG budgets. However, many of our flux estimates are uncertain and it can be discussed if the presently available data is representative for the systems studied or not. Data are also very limited for some important flux pathways. Hence, many ongoing efforts try to better constrain fluxes and understand flux regulation. A fundamental challenge towards improved knowledge and when starting new studies is what methods to choose. A variety of approaches to measure aquatic GHG exchange is used and data from different methods and methodological approaches have often been treated as equally valid to create large datasets for extrapolations and syntheses. However, data from different approaches may cover different flux pathways or spatio-temporal domains and are thus not always comparable. Method inter-comparisons and critical method evaluations addressing these issues are rare. Emerging efforts to organize systematic multi-lake monitoring networks for GHG fluxes leads to method choices that may set the foundation for decades of data generation and therefore require fundamental evaluation of different approaches. The method choices do not only regard the equipment but also for example consideration of overall measurement design and field approaches, relevant spatial and temporal resolution for different flux components, and accessory variables to measure. In addition, consideration of how to design monitoring approaches being affordable, suitable for widespread (global) use, and comparable across regions is needed. Inspired by discussions with Prof. Dr. Cristian Blodau during the EGU General Assembly 2016, this presentation aims to (1) illustrate fundamental pros and cons for a number of common methods, (2) show how common methodological approaches originally adapted for other environments can be improved for lake flux measurements, (3) suggest

  8. Low Permafrost Methane Emissions from Arctic Airborne Flux Measurements

    NASA Astrophysics Data System (ADS)

    Sachs, T.; Serafimovich, A.; Metzger, S.; Kohnert, K.; Hartmann, J.

    2014-12-01

    One of the most pressing questions with regard to climate feedback processes in a warming Arctic is the regional-scale greenhouse gas release from Arctic permafrost areas. Ground-based eddy covariance (EC) measurements provide continuous in-situ observations of the surface-atmosphere exchange of energy and matter. However, these observations are rare in the Arctic permafrost zone and site selection is bound by logistical constraints among others. Consequently, these observations cover only small areas that are not necessarily representative of the region of interest. Airborne measurements can overcome this limitation by covering distances of hundreds of kilometers over time periods of a few hours. The Airborne Measurements of Methane Fluxes (AIRMETH) campaigns are designed to quantitatively and spatially explicitly address this question. During the AIRMETH-2012 and AIRMETH-2013 campaigns aboard the research aircraft POLAR 5 we measured turbulent exchange of energy, methane, and (in 2013) carbon dioxide along thousands of kilometers covering the North Slope of Alaska and the Mackenzie Delta, Canada. Time-frequency (wavelet) analysis, footprint modeling, and machine learning techniques are used to (i) determine spatially resolved turbulence statistics, fluxes, and contributions of biophysical surface properties, and (ii) extract regionally valid functional relationships between environmental drivers and the observed fluxes. These environmental response functions (ERF) are used to explain spatial flux patterns and - if drivers are available in temporal resolution - allow for spatio-temporal scaling of the observations. This presentation will focus on 2012 methane fluxes on the North Slope of Alaska and the relevant processes on the regional scale and provide an updated 100 m resolution methane flux map of the North Slope of Alaska.

  9. Absolute distance measurement by dual-comb interferometry with multi-channel digital lock-in phase detection

    NASA Astrophysics Data System (ADS)

    Yang, Ruitao; Pollinger, Florian; Meiners-Hagen, Karl; Krystek, Michael; Tan, Jiubin; Bosse, Harald

    2015-08-01

    We present a dual-comb-based heterodyne multi-wavelength absolute interferometer capable of long distance measurements. The phase information of the various comb modes is extracted in parallel by a multi-channel digital lock-in phase detection scheme. Several synthetic wavelengths of the same order are constructed and the corresponding phases are averaged to deduce the absolute lengths with significantly reduced uncertainty. Comparison experiments with an incremental HeNe reference interferometer show a combined relative measurement uncertainty of 5.3 × 10-7 at a measurement distance of 20 m. Combining the advantage of synthetic wavelength interferometry and dual-comb interferometry, our compact and simple approach provides sufficient precision for many industrial applications.

  10. Gravity wave momentum flux estimation from CRISTA satellite data

    NASA Astrophysics Data System (ADS)

    Ern, M.; Preusse, P.; Alexander, M. J.; Offermann, D.

    2003-04-01

    Temperature altitude profiles measured by the CRISTA satellite were analyzed for gravity waves (GWs). Amplitudes, vertical and horizontal wavelengths of GWs are retrieved by applying a combination of maximum entropy method (MEM) and harmonic analysis (HA) to the temperature height profiles and subsequently comparing the so retrieved GW phases of adjacent altitude profiles. From these results global maps of the absolute value of the vertical flux of horizontal momentum have been estimated. Significant differences between distributions of the temperature variance and distributions of the momentum flux exist. For example, global maps of the momentum flux show a pronounced northward shift of the equatorial maximum whereas temperature variance maps of the tropics/subtropics are nearly symmetric with respect to the equator. This indicates the importance of the influence of horizontal and vertical wavelength distribution on global structures of the momentum flux.

  11. Measurement of the photoneutron flux density distribution from cylindrical targets

    NASA Astrophysics Data System (ADS)

    Golovkov, V. M.; Basina, T. N.; Yakovlev, M. R.

    1989-09-01

    Measurements are performed of the density of photoneutron fluxes from cylindrical targets of2H2O (diameter 64 and height 86 mm), Be (outer diameter 70, inner diameter 40, height 100mm), and238U (diameter 44.5 mm, height 50 mm) under the action of braking radiation from electrons with energies of 4 to 8 MeV in order to determine the effect of target form and orientation relative to the detector upon the recorded photoneutron level. The fluxes were measured by an “all-wave” neutron detector based on an SNM-11 counter in a paraffin retarder at an angle of 90‡ to the axis of the braking radiation beam for various target orientations relative to the detector. Measurement results are compared to calculations. Photoneutron fluxes from heavy water and beryllium targets of the indicated dimensions were also measured for angles of 90, 135, and 167‡. An isotropic nature was noted in the photoneutron fluxes from both targets.

  12. Absolute measures of the completeness of the fossil record

    NASA Technical Reports Server (NTRS)

    Foote, M.; Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

    1999-01-01

    Measuring the completeness of the fossil record is essential to understanding evolution over long timescales, particularly when comparing evolutionary patterns among biological groups with different preservational properties. Completeness measures have been presented for various groups based on gaps in the stratigraphic ranges of fossil taxa and on hypothetical lineages implied by estimated evolutionary trees. Here we present and compare quantitative, widely applicable absolute measures of completeness at two taxonomic levels for a broader sample of higher taxa of marine animals than has previously been available. We provide an estimate of the probability of genus preservation per stratigraphic interval, and determine the proportion of living families with some fossil record. The two completeness measures use very different data and calculations. The probability of genus preservation depends almost entirely on the Palaeozoic and Mesozoic records, whereas the proportion of living families with a fossil record is influenced largely by Cenozoic data. These measurements are nonetheless highly correlated, with outliers quite explicable, and we find that completeness is rather high for many animal groups.

  13. Flux measurements of volatile organic compounds from an urban landscape

    NASA Astrophysics Data System (ADS)

    Velasco, E.; Lamb, B.; Pressley, S.; Allwine, E.; Westberg, H.; Jobson, B. T.; Alexander, M.; Prazeller, P.; Molina, L.; Molina, M.

    2005-10-01

    Direct measurements of volatile organic compound (VOC) emissions that include all sources in urban areas are a missing requirement to evaluate emission inventories and constrain current photochemical modelling practices. Here we demonstrate the use of micrometeorological techniques coupled with fast-response sensors to measure urban VOC fluxes from a neighbourhood of Mexico City, where the spatial variability of surface cover and roughness is high. Fluxes of olefins, methanol, acetone, toluene and C2-benzenes were measured and compared with the local gridded emissions inventory. VOC fluxes exhibited a clear diurnal pattern with a strong relationship to vehicular traffic. Recent photochemical modelling results suggest that VOC emissions are significantly underestimated in Mexico City, but for the olefin class, toluene, C2-benzenes, and acetone fluxes measured in this work, the results show general agreement with the gridded emissions inventory. While these measurements do not address the full suite of VOC emissions, the comparison with the inventory suggests that other explanations may be needed to explain the photochemical modelling results.

  14. Interactive Database of Pulsar Flux Density Measurements

    NASA Astrophysics Data System (ADS)

    Koralewska, O.; Krzeszowski, K.; Kijak, J.; Lewandowski, W.

    2012-12-01

    The number of astronomical observations is steadily growing, giving rise to the need of cataloguing the obtained results. There are a lot of databases, created to store different types of data and serve a variety of purposes, e. g. databases providing basic data for astronomical objects (SIMBAD Astronomical Database), databases devoted to one type of astronomical object (ATNF Pulsar Database) or to a set of values of the specific parameter (Lorimer 1995 - database of flux density measurements for 280 pulsars on the frequencies up to 1606 MHz), etc. We found that creating an online database of pulsar flux measurements, provided with facilities for plotting diagrams and histograms, calculating mean values for a chosen set of data, filtering parameter values and adding new measurements by the registered users, could be useful in further studies on pulsar spectra.

  15. Improved Measurement of Reactor Flux and Spectrum at Daya Bay

    NASA Astrophysics Data System (ADS)

    Zhan, Liang; Daya Bay Collaboration

    2017-09-01

    A new measurement of the reactor antineutrino flux and energy spectrum by the Daya Bay experiment is reported. With a live time of 621 days, more than 1.2 million inverse beta decay (IBD) candidates were collected by eight antineutrino detectors (ADs) deployed in two near (560 m and 600 m flux-weighted baselines) and one far (16400 m flux-weighted baseline) underground experimental halls. The IBD yield was measured and the ratio to the predicted flux using the Huber+Mueller (ILL+Vogel) model was determined to be 0.946 ± 0.020 (0.992 ± 0.021). A 2.9 σ deviation was found in the measured IBD positron energy spectrum compared to the predictions. In particular, an excess of events in the region of 4-6 MeV was found with a local significance of 4.4 σ.

  16. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  17. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  18. Analysis of actinic flux profiles measured from an ozonesonde balloon

    NASA Astrophysics Data System (ADS)

    Wang, P.; Allaart, M.; Knap, W. H.; Stammes, P.

    2015-04-01

    A green light sensor has been developed at KNMI to measure actinic flux profiles using an ozonesonde balloon. In total, 63 launches with ascending and descending profiles were performed between 2006 and 2010. The measured uncalibrated actinic flux profiles are analysed using the Doubling-Adding KNMI (DAK) radiative transfer model. Values of the cloud optical thickness (COT) along the flight track were taken from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) Cloud Physical Properties (CPP) product. The impact of clouds on the actinic flux profile is evaluated on the basis of the cloud modification factor (CMF) at the cloud top and cloud base, which is the ratio between the actinic fluxes for cloudy and clear-sky scenes. The impact of clouds on the actinic flux is clearly detected: the largest enhancement occurs at the cloud top due to multiple scattering. The actinic flux decreases almost linearly from cloud top to cloud base. Above the cloud top the actinic flux also increases compared to clear-sky scenes. We find that clouds can increase the actinic flux to 2.3 times the clear-sky value at cloud top and decrease it to about 0.05 at cloud base. The relationship between CMF and COT agrees well with DAK simulations, except for a few outliers. Good agreement is found between the DAK-simulated actinic flux profiles and the observations for single-layer clouds in fully overcast scenes. The instrument is suitable for operational balloon measurements because of its simplicity and low cost. It is worth further developing the instrument and launching it together with atmospheric chemistry composition sensors.

  19. Validation of two innovative methods to measure contaminant mass flux in groundwater

    NASA Astrophysics Data System (ADS)

    Goltz, Mark N.; Close, Murray E.; Yoon, Hyouk; Huang, Junqi; Flintoft, Mark J.; Kim, Sehjong; Enfield, Carl

    2009-04-01

    The ability to quantify the mass flux of a groundwater contaminant that is leaching from a source area is critical to enable us to: (1) evaluate the risk posed by the contamination source and prioritize cleanup, (2) evaluate the effectiveness of source remediation technologies or natural attenuation processes, and (3) quantify a source term for use in models that may be applied to predict maximum contaminant concentrations in downstream wells. Recently, a number of new methods have been developed and subsequently applied to measure contaminant mass flux in groundwater in the field. However, none of these methods has been validated at larger than the laboratory-scale through a comparison of measured mass flux and a known flux that has been introduced into flowing groundwater. A couple of innovative flux measurement methods, the tandem circulation well (TCW) and modified integral pumping test (MIPT) methods, have recently been proposed. The TCW method can measure mass flux integrated over a large subsurface volume without extracting water. The TCW method may be implemented using two different techniques. One technique, the multi-dipole technique, is relatively simple and inexpensive, only requiring measurement of heads, while the second technique requires conducting a tracer test. The MIPT method is an easily implemented method of obtaining volume-integrated flux measurements. In the current study, flux measurements obtained using these two methods are compared with known mass fluxes in a three-dimensional, artificial aquifer. Experiments in the artificial aquifer show that the TCW multi-dipole and tracer test techniques accurately estimated flux, within 2% and 16%, respectively; although the good results obtained using the multi-dipole technique may be fortuitous. The MIPT method was not as accurate as the TCW method, underestimating flux by as much as 70%. MIPT method inaccuracies may be due to the fact that the method assumptions (two-dimensional steady

  20. N2O eddy covariance fluxes: From field measurements to flux calculation

    NASA Astrophysics Data System (ADS)

    Lognoul, Margaux; Debacq, Alain; Heinesch, Bernard; Aubinet, Marc

    2017-04-01

    From March to October 2016, we performed eddy covariance measurements in a sugar beet crop at the Lonzée Terrestrial Observatory (LTO, candidate ICOS site) in Belgium. N2O and H2O atmospheric concentrations were measured at 10 Hz using a quantum-cascade laser spectrometer (Aerodyne Research, Inc.) and combined to wind speed 3D components measured with a sonic anemometer (Gill HS-50). Flux computation was carried out using the EddyPro Software (LI-COR) with a focus on adaptations needed for tracers like N2O. Data filtering and quality control were performed according to Vickers and Mahrt (1997) and Mauder and Foken (2004). The flags were adapted to N2O time series. In this presentation, different computation steps will be presented. More specifically: 1) Considering that a large proportion of N2O fluxes are small (within ± 0.5 nmol m-2 s-1), the classical stationarity test might lead to excessive data filtering and in such case, some searchers have chosen to use the running mean (RM) as a detrend method over block averaging (BA) and to filter data otherwise. For our dataset, BA mean fluxes combined to the stationarity test did not significantly differ from RM fluxes when the averaging window was 300s or larger, but were significantly larger otherwise, suggesting that significant eddies occurred at the 5-min timescale and that they were not accounted for with a shorter averaging window. 2) The determination of time-lag in the case of N2O fluxes can become tricky for two reasons : (1) the signal amplitude can differ from one time period to the next, making it difficult to use the method of covariance maximization and (2) an additional clock drift can appear if the spectrometer is not logging on the same computer than the anemometer. In our case, the N2O signal was strong enough to solve both problems and to perform time-lag compensation according to the covariance maximization, with a default value equal to the mode of the lag distribution. The automatic time

  1. Method and apparatus for making absolute range measurements

    DOEpatents

    Earl, Dennis D [Knoxville, TN; Allison, Stephen W [Knoxville, TN; Cates, Michael R [Oak Ridge, TN; Sanders, Alvin J [Knoxville, TN

    2002-09-24

    This invention relates to a method and apparatus for making absolute distance or ranging measurements using Fresnel diffraction. The invention employs a source of electromagnetic radiation having a known wavelength or wavelength distribution, which sends a beam of electromagnetic radiation through a screen at least partially opaque at the wavelength. The screen has an aperture sized so as to produce a Fresnel diffraction pattern. A portion of the beam travels through the aperture to a detector spaced some distance from the screen. The detector detects the central intensity of the beam as well as a set of intensities displaced from a center of the aperture. The distance from the source to the target can then be calculated based upon the known wavelength, aperture radius, and beam intensity.

  2. Analysis of standard reference materials by absolute INAA

    NASA Astrophysics Data System (ADS)

    Heft, R. E.; Koszykowski, R. F.

    1981-07-01

    Three standard reference materials: flyash, soil, and ASI 4340 steel, are analyzed by a method of absolute instrumental neutron activation analysis. Two different light water pool-type reactors were used to produce equivalent analytical results even though the epithermal to thermal flux ratio in one reactor was higher than that in the other by a factor of two.

  3. Metabolic flux analysis using 13C peptide label measurements

    USDA-ARS?s Scientific Manuscript database

    13C metabolic flux analysis (MFA) has become the experimental method of choice to investigate cellular metabolism. MFA has established flux maps of central metabolism for dozens of microbes, cell cultures, and plant seeds. Steady-state MFA utilizes isotopic labeling measurements of amino acids obtai...

  4. The Airborne Measurements of Methane Fluxes (AIRMETH) Arctic Campaign (Invited)

    NASA Astrophysics Data System (ADS)

    Serafimovich, A.; Metzger, S.; Hartmann, J.; Kohnert, K.; Sachs, T.

    2013-12-01

    One of the most pressing questions with regard to climate feedback processes in a warming Arctic is the regional-scale methane release from Arctic permafrost areas. The Airborne Measurements of Methane Fluxes (AIRMETH) campaign is designed to quantitatively and spatially explicitly address this question. Ground-based eddy covariance (EC) measurements provide continuous in-situ observations of the surface-atmosphere exchange of methane. However, these observations are rare in the Arctic permafrost zone and site selection is bound by logistical constraints among others. Consequently, these observations cover only small areas that are not necessarily representative of the region of interest. Airborne measurements can overcome this limitation by covering distances of hundreds of kilometers over time periods of a few hours. Here, we present the potential of environmental response functions (ERFs) for quantitatively linking methane flux observations in the atmospheric surface layer to meteorological and biophysical drivers in the flux footprints. For this purpose thousands of kilometers of AIRMETH data across the Alaskan North Slope are utilized, with the aim to extrapolate the airborne EC methane flux observations to the entire North Slope. The data were collected aboard the research aircraft POLAR 5, using its turbulence nose boom and fast response methane and meteorological sensors. After thorough data pre-processing, Reynolds averaging is used to derive spatially integrated fluxes. To increase spatial resolution and to derive ERFs, we then use wavelet transforms of the original high-frequency data. This enables much improved spatial discretization of the flux observations, and the quantification of continuous and biophysically relevant land cover properties in the flux footprint of each observation. A machine learning technique is then employed to extract and quantify the functional relationships between the methane flux observations and the meteorological and

  5. Intercalibration of benthic flux chambers I. Accuracy of flux measurements and influence of chamber hydrodynamics [review article

    NASA Astrophysics Data System (ADS)

    Tengberg, A.; Stahl, H.; Gust, G.; Müller, V.; Arning, U.; Andersson, H.; Hall, P. O. J.

    2004-01-01

    The hydrodynamic properties and the capability to measure sediment-water solute fluxes, at assumed steady state conditions, were compared for three radically different benthic chamber designs: the “Microcosm”, the “Mississippi” and the “Göteborg” chambers. The hydrodynamic properties were characterized by mounting a PVC bottom in each chamber and measuring mixing time, diffusive boundary layer thickness (DBL thickness) shear velocity (u ∗) , and total pressure created by the water mixing. The Microcosm had the most even distribution of DBL thickness and u ∗, but the highest differential pressure at high water mixing rates. The Mississippi chamber had low differential pressures at high u ∗. The Göteborg chamber was in between the two others regarding these properties. DBL thickness and u ∗ were found to correlate according to the following empirical formula: DBL=76.18(u ∗) -0.933. Multiple flux incubations with replicates of each of the chamber types were carried out on homogenized, macrofauna-free sediments in four tanks. The degree of homogeneity was determined by calculating solute fluxes (of oxygen, silicate, phosphate and ammonium) from porewater profiles and by sampling for porosity, organic carbon and meiofauna. All these results, except meiofauna, indicated that there were no significant horizontal variations within the sediment in any of the parallel incubation experiments. The statistical evaluations also suggested that the occasional variations in meiofauna abundance did not have any influence on the measured solute fluxes. Forty-three microelectrode profiles of oxygen in the DBL and porewater were evaluated with four different procedures to calculate diffusive fluxes. The procedure presented by Berg, Risgaard-Petersen and Rysgaard, 1989 [Limnol. Oceanogr. 43, 1500] was found to be superior because of its ability to fit measured profiles accurately, and because it takes into consideration vertical zonation with different oxygen

  6. Classical Heat-Flux Measurements in Coronal Plasmas from Collective Thomson-Scattering Spectra

    NASA Astrophysics Data System (ADS)

    Henchen, R. J.; Hu, S. X.; Katz, J.; Froula, D. H.; Rozmus, W.

    2016-10-01

    Collective Thomson scattering was used to measure heat flux in coronal plasmas. The relative amplitude of the Thomson-scattered power into the up- and downshifted electron plasma wave features was used to determine the flux of electrons moving along the temperature gradient at three to four times the electron thermal velocity. Simultaneously, the ion-acoustic wave features were measured. Their relative amplitude was used to measure the flux of the return-current electrons. The frequencies of these ion-acoustic and electron plasma wave features provide local measurements of the electron temperature and density. These spectra were obtained at five locations along the temperature gradient in a laser-produced blowoff plasma. These measurements of plasma parameters are used to infer the Spitzer-Härm flux (qSH = - κ∇Te ) and are in good agreement with the values of the heat flux measured from the scattering-feature asymmetries. Additional experiments probed plasma waves perpendicular to the temperature gradient. The data show small effects resulting from heat flux compared to probing waves along the temperature gradient. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  7. High geothermal heat flux measured below the West Antarctic Ice Sheet

    PubMed Central

    Fisher, Andrew T.; Mankoff, Kenneth D.; Tulaczyk, Slawek M.; Tyler, Scott W.; Foley, Neil

    2015-01-01

    The geothermal heat flux is a critical thermal boundary condition that influences the melting, flow, and mass balance of ice sheets, but measurements of this parameter are difficult to make in ice-covered regions. We report the first direct measurement of geothermal heat flux into the base of the West Antarctic Ice Sheet (WAIS), below Subglacial Lake Whillans, determined from the thermal gradient and the thermal conductivity of sediment under the lake. The heat flux at this site is 285 ± 80 mW/m2, significantly higher than the continental and regional averages estimated for this site using regional geophysical and glaciological models. Independent temperature measurements in the ice indicate an upward heat flux through the WAIS of 105 ± 13 mW/m2. The difference between these heat flux values could contribute to basal melting and/or be advected from Subglacial Lake Whillans by flowing water. The high geothermal heat flux may help to explain why ice streams and subglacial lakes are so abundant and dynamic in this region. PMID:26601210

  8. High geothermal heat flux measured below the West Antarctic Ice Sheet.

    PubMed

    Fisher, Andrew T; Mankoff, Kenneth D; Tulaczyk, Slawek M; Tyler, Scott W; Foley, Neil

    2015-07-01

    The geothermal heat flux is a critical thermal boundary condition that influences the melting, flow, and mass balance of ice sheets, but measurements of this parameter are difficult to make in ice-covered regions. We report the first direct measurement of geothermal heat flux into the base of the West Antarctic Ice Sheet (WAIS), below Subglacial Lake Whillans, determined from the thermal gradient and the thermal conductivity of sediment under the lake. The heat flux at this site is 285 ± 80 mW/m(2), significantly higher than the continental and regional averages estimated for this site using regional geophysical and glaciological models. Independent temperature measurements in the ice indicate an upward heat flux through the WAIS of 105 ± 13 mW/m(2). The difference between these heat flux values could contribute to basal melting and/or be advected from Subglacial Lake Whillans by flowing water. The high geothermal heat flux may help to explain why ice streams and subglacial lakes are so abundant and dynamic in this region.

  9. Eddy Covariance Measurements of Methane Flux Using an Open-Path Gas Analyzer

    NASA Astrophysics Data System (ADS)

    Burba, G.; Anderson, T.; Zona, D.; Schedlbauer, J.; Anderson, D.; Eckles, R.; Hastings, S.; Ikawa, H.; McDermitt, D.; Oberbauer, S.; Oechel, W.; Riensche, B.; Starr, G.; Sturtevant, C.; Xu, L.

    2008-12-01

    Methane is an important greenhouse gas with a warming potential of about 23 times that of carbon dioxide over a 100-year cycle (Houghton et al., 2001). Measurements of methane fluxes from the terrestrial biosphere have mostly been made using flux chambers, which have many advantages, but are discrete in time and space and may disturb surface integrity and air pressure. Open-path analyzers offer a number of advantages for measuring methane fluxes, including undisturbed in- situ flux measurements, spatial integration using the Eddy Covariance approach, zero frequency response errors due to tube attenuation, confident water and thermal density terms from co-located fast measurements of water and sonic temperature, and remote deployment due to lower power demands in the absence of a pump. The prototype open-path methane analyzer is a VCSEL (vertical-cavity surface-emitting laser)-based instrument. It employs an open Herriott cell and measures levels of methane with RMS noise below 6 ppb at 10 Hz sampling in controlled laboratory environment. Field maintenance is minimized by a self-cleaning mechanism to keep the lower mirror free of contamination. Eddy Covariance measurements of methane flux using the prototype open-path methane analyzer are presented for the period between 2006 and 2008 in three ecosystems with contrasting weather and moisture conditions: (1) Fluxes over a short-hydroperiod sawgrass wetland in the Florida Everglades were measured in a warm and humid environment with temperatures often exceeding 25oC, variable winds, and frequent heavy dew at night; (2) Fluxes over coastal wetlands in an Arctic tundra were measured in an environment with frequent sub-zero temperatures, moderate winds, and ocean mist; (3) Fluxes over pacific mangroves in Mexico were measured in an environment with moderate air temperatures high winds, and sea spray. Presented eddy covariance flux data were collected from a co-located prototype open-path methane analyzer, LI-7500, and

  10. The Absolute Measurement of Beta Activities; SOBRE LA MEDIDA ABSOLUTA DE ACTIVIDADES BETA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Del Rio, C.S.; Reynaldo, O.J.; Mayquez, E.R.

    1956-01-01

    A new method for the absolute beta counting of solid samples is given. The measurements are made with an inside Geiger-Muller tube of new construction. The backscattering correction, when using an "infinite" thick mounting, is discussed and results for different materials given. (auth)

  11. Turbulent Surface Flux Measurements over Snow-Covered Sea Ice

    NASA Astrophysics Data System (ADS)

    Andreas, E. L.; Fairall, C. W.; Grachev, A. A.; Guest, P. S.; Jordan, R. E.; Persson, P. G.

    2006-12-01

    Our group has used eddy correlation to make over 10,000 hours of measurements of the turbulent momentum and heat fluxes over snow-covered sea ice in both the Arctic and the Antarctic. Polar sea ice is an ideal site for studying fundamental processes for turbulent exchange over snow. Both our Arctic and Antarctic sites---in the Beaufort Gyre and deep into the Weddell Sea, respectively---were expansive, flat areas with continuous snow cover; and both were at least 300 km from any topography that might have complicated the atmospheric flow. In this presentation, we will review our measurements of the turbulent fluxes of momentum and sensible and latent heat. In particular, we will describe our experiences making turbulence instruments work in the fairly harsh polar, marine boundary layer. For instance, several of our Arctic sites were remote from our main camp and ran unattended for a week at a time. Besides simply making flux measurements, we have been using the data to develop a bulk flux algorithm and to study fundamental turbulence processes in the atmospheric surface layer. The bulk flux algorithm predicts the turbulent surface fluxes from mean meteorological quantities and, thus, will find use in data analyses and models. For example, components of the algorithm are already embedded in our one- dimensional mass and energy budget model SNTHERM. Our fundamental turbulence studies have included deducing new scaling regimes in the stable boundary layer; examining the Monin-Obukhov similarity functions, especially in stable stratification; and evaluating the von Kármán constant with the largest atmospheric data set ever applied to such a study. During this presentation, we will highlight some of this work.

  12. Absolute sensitivity calibration of an extreme ultraviolet spectrometer for tokamak measurements

    NASA Astrophysics Data System (ADS)

    Guirlet, R.; Schwob, J. L.; Meyer, O.; Vartanian, S.

    2017-01-01

    An extreme ultraviolet spectrometer installed on the Tore Supra tokamak has been calibrated in absolute units of brightness in the range 10-340 Å. This has been performed by means of a combination of techniques. The range 10-113 Å was absolutely calibrated by using an ultrasoft-X ray source emitting six spectral lines in this range. The calibration transfer to the range 113-182 Å was performed using the spectral line intensity branching ratio method. The range 182-340 Å was calibrated thanks to radiative-collisional modelling of spectral line intensity ratios. The maximum sensitivity of the spectrometer was found to lie around 100 Å. Around this wavelength, the sensitivity is fairly flat in a 80 Å wide interval. The spatial variations of sensitivity along the detector assembly were also measured. The observed trend is related to the quantum efficiency decrease as the angle of the incoming photon trajectories becomes more grazing.

  13. Optoelectronic device for the measurement of the absolute linear position in the micrometric displacement range

    NASA Astrophysics Data System (ADS)

    Morlanes, Tomas; de la Pena, Jose L.; Sanchez-Brea, Luis M.; Alonso, Jose; Crespo, Daniel; Saez-Landete, Jose B.; Bernabeu, Eusebio

    2005-07-01

    In this work, an optoelectronic device that provides the absolute position of a measurement element with respect to a pattern scale upon switch-on is presented. That means that there is not a need to perform any kind of transversal displacement after the startup of the system. The optoelectronic device is based on the process of light propagation passing through a slit. A light source with a definite size guarantees the relation of distances between the different elements that constitute our system and allows getting a particular optical intensity profile that can be measured by an electronic post-processing device providing the absolute location of the system with a resolution of 1 micron. The accuracy of this measuring device is restricted to the same limitations of any incremental position optical encoder.

  14. The truth is out there: measured, calculated and modelled benthic fluxes.

    NASA Astrophysics Data System (ADS)

    Pakhomova, Svetlana; Protsenko, Elizaveta

    2016-04-01

    In a modern Earth science there is a great importance of understanding the processes, forming the benthic fluxes as one of element sources or sinks to or from the water body, which affects the elements balance in the water system. There are several ways to assess benthic fluxes and here we try to compare the results obtained by chamber experiments, calculated from porewater distributions and simulated with model. Benthic fluxes of dissolved elements (oxygen, nitrogen species, phosphate, silicate, alkalinity, iron and manganese species) were studied in the Baltic and Black Seas from 2000 to 2005. Fluxes were measured in situ using chamber incubations (Jch) and at the same time sediment cores were collected to assess the porewater distribution at different depths to calculate diffusive fluxes (Jpw). Model study was carried out with benthic-pelagic biogeochemical model BROM (O-N-P-Si-C-S-Mn-Fe redox model). It was applied to simulate biogeochemical structure of the water column and upper sediment and to assess the vertical fluxes (Jmd). By the behaviour at the water-sediment interface all studied elements can be divided into three groups: (1) elements which benthic fluxes are determined by the concentrations gradient only (Si, Mn), (2) elements which fluxes depend on redox conditions in the bottom water (Fe, PO4, NH4), and (3) elements which fluxes are strongly connected with organic matter fate (O2, Alk, NH4). For the first group it was found that measured fluxes are always higher than calculated diffusive fluxes (1.5flux. In this case bioturbation, bioirrigation and advection should be taken into account. For the second group measured fluxes can be both much lower (practically absent) and much higher than calculated diffusive fluxes (0.01

  15. Assessing and correcting spatial representativeness of tower eddy-covariance flux measurements

    NASA Astrophysics Data System (ADS)

    Metzger, S.; Xu, K.; Desai, A. R.; Taylor, J. R.; Kljun, N.; Blanken, P.; Burns, S. P.; Scott, R. L.

    2014-12-01

    Estimating the landscape-scale exchange of ecologically relevant trace gas and energy fluxes from tower eddy-covariance (EC) measurements is often complicated by surface heterogeneity. For example, a tower EC measurement may represent less than 1% of a grid cell resolved by mechanistic models (order 100-1000 km2). In particular for data assimilation or comparison with large-scale observations, it is hence critical to assess and correct the spatial representativeness of tower EC measurements. We present a procedure that determines from a single EC tower the spatio-temporally explicit flux field of its surrounding. The underlying principle is to extract the relationship between biophysical drivers and ecological responses from measurements under varying environmental conditions. For this purpose, high-frequency EC flux processing and source area calculations (≈60 h-1) are combined with remote sensing retrievals of land surface properties and subsequent machine learning. Methodological details are provided in our companion presentation "Towards the spatial rectification of tower-based eddy-covariance flux observations". We apply the procedure to one year of data from each of four AmeriFlux sites under different climate and ecological environments: Lost Creek shrub fen wetland, Niwot Ridge subalpine conifer, Park Falls mixed forest, and Santa Rita mesquite savanna. We find that heat fluxes from the Park Falls 122-m-high EC measurement and from a surrounding 100 km2 target area differ up to 100 W m-2, or 65%. Moreover, 85% and 24% of the EC flux observations are adequate surrogates of the mean surface-atmosphere exchange and its spatial variability across a 900 km2 target area, respectively, at 5% significance and 80% representativeness levels. Alternatively, the resulting flux grids can be summarized as probability density functions, and used to inform mechanistic models directly with the mean flux value and its spatial variability across a model grid cell. Lastly

  16. Improving mercury flux chamber measurements over water surface.

    PubMed

    Lanzillotra, E; Ceccarini, C; Ferrara, R

    2003-07-01

    A modified floating flux chamber was designed and used to measure mercury evasional fluxes in a coastal area of the Mediterranean Sea in different meteo-marine conditions during the hours of maximum insolation (PAR intensity 360-430 W m(-2)) in the summer season. The chamber has been modified providing a flap at the inlet port preventing the back-flow of air from the interior of the chamber. Results demonstrate that the modified flux chamber gives flux values noticeably higher both in rippled sea conditions (mean value 7.88 +/- 1.45 ng m(-2) h(-1)) and in rough sea conditions (mean value 21.71 +/- 2.17 ng m(-2) h(-1)) with respect to those obtained by using the unmodified chamber (respectively 5.23 +/- 0.67 and 14.15 +/- 1.03 ng m(-2) h(-1)).

  17. Progress in the measurement of SSME turbine heat flux with plug-type sensors

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.

    1991-01-01

    Data reduction was completed for tests of plug-type heat flux sensors (gauges) in a turbine blade thermal cycling tester (TBT) that is located at NASA/Marshall Space Flight Center, and a typical gauge is illustrated. This is the first time that heat flux has been measured in a Space Shuttle Main Engine (SSME) Turbopump Turbine environment. The development of the concept for the gauge was performed in a heat flux measurement facility at Lewis. In this facility, transient and steady state absorbed surface heat flux information was obtained from transient temperature measurements taken at points within the gauge. A schematic of the TBT is presented, and plots of the absorbed surface heat flux measured on the three blades tested in the TBT are presented. High quality heat flux values were measured on all three blades. The experiments demonstrated that reliable and durable gauges can be repeatedly fabricated into the airfoils. The experiment heat flux data are being used for verification of SSME analytical stress, boundary layer, and heat transfer design models. Other experimental results and future plans are also presented.

  18. A digital wide range neutron flux measuring system for HL-2A

    NASA Astrophysics Data System (ADS)

    Yuan, Chen; Wu, Jun; Yin, Zejie

    2017-08-01

    To achieve wide-range, high-integration, and real-time performance on the neutron flux measurement on the HL-2A tokamak, a digital neutron flux measuring (DNFM) system based on the peripheral component interconnection (PCI) eXtension for Instrumentation express (PXIe) bus was designed. This system comprises a charge-sensitive preamplifier and a field programmable gate array (FPGA)-based main electronics plug-in. The DNFM totally covers source-range and intermediate-range neutron flux measurements, and increases system integration by a large margin through joining the pulse-counting mode and Campbell mode. Meanwhile, the neutron flux estimation method based on pulse piling proportions is able to choose and switch measuring modes in accordance with current flux, and this ensures the accuracy of measurements when the neutron flux changes suddenly. It has been demonstrated by simulated signals that the DNFM enhances the full-scale measuring range up to 1.9 × 108 cm-2 s-1, with relative error below 6.1%. The DNFM has been verified to provide a high temporal sensitivity at 10 ms time intervals on a single fission chamber on HL-2A. Contributed paper, published as part of the Proceedings of the 3rd Domestic Electromagnetic Plasma Diagnostics Workshop, September 2016, Hefei, China.

  19. Pulse energy measurement at the SXR instrument

    DOE PAGES

    Moeller, Stefan; Brown, Garth; Dakovski, Georgi; ...

    2015-04-14

    A gas monitor detector was implemented and characterized at the Soft X-ray Research (SXR) instrument to measure the average, absolute and pulse-resolved photon flux of the LCLS beam in the energy range between 280 and 2000 eV. The detector is placed after the monochromator and addresses the need to provide reliable absolute pulse energy as well as pulse-resolved measurements for the various experiments at this instrument. This detector provides a reliable non-invasive measurement for determining flux levels on the samples in the downstream experimental chamber and for optimizing signal levels of secondary detectors and for the essential need of datamore » normalization. The design, integration into the instrument and operation are described, and examples of its performance are given.« less

  20. What can we learn about ammonia fluxes from open-path eddy covariance measurements?

    NASA Astrophysics Data System (ADS)

    Pan, D.; Zondlo, M. A.; Benedict, K. B.; Schichtel, B. A.; Ham, J. M.; Shonkwiler, K. B.; Collett, J. L., Jr.

    2016-12-01

    Ammonia (NH3) is an important component of bio-atmospheric N cycle with implications of regional air quality, human and ecosystem health degradation, and global climate change. NH3 fluxes have high spatiotemporal variability controlled by several factors, such as atmospheric NH3 concentration, meteorological conditions, and compensation point of underlying surfaces. Quantifying NH3 fluxes is further complicated by severe measurement challenges including adsorption to instrument surfaces, low mole fractions, and gas-particle phase partitioning. To overcome these challenges, we have developed an open-path, eddy covariance NH3 instrument that minimizes these sampling issues. Eddy covariance measurements in 2015 and 2016 in the Rocky Mountain National Park (RMNP), Colorado showed the capabilities of the system to measure fluxes in clean and moderate-polluted regions. Interesting patterns of NH3 fluxes and NH3 concentration variations were observed, such as deposition of NH3 associated plumes from urban and agricultural areas and reemission of a similar magnitude when clean free-tropospheric air passing the site. Observed downward fluxes during midnight and upward fluxes in early morning also indicated NH3 fluxes related to dew formation and evaporation events. More details about these patterns and their relationships with ambient temperature, relative humidity, and other fluxes will be presented. These measurements also provided an opportunity to evaluate our current understanding of transport and deposition of NH3. Micrometeorological method, backward trajectory model, and bidirectional NH3 flux model were used to analyze observed variability of NH3 concentrations and fluxes. Implications of these results and how eddy covariance measurements combined with other measurements may provide insights to better quantify NH3 fluxes will be discussed.

  1. Simultaneous measurement of absolute strain and differential strain based on fiber Bragg grating Fabry-Perot sensor

    NASA Astrophysics Data System (ADS)

    Wang, Kuiru; Wang, Bo; Yan, Binbin; Sang, Xinzhu; Yuan, Jinhui; Peng, Gang-Ding

    2013-10-01

    We present a fiber Bragg grating Fabry-Perot (FBG-FP) sensor using the fast Fourier transform (FFT) demodulation for measuring the absolute strain and differential strain simultaneously. The amplitude and phase characteristics of Fourier transform spectrum have been studied. The relation between the amplitude of Fourier spectrum and the differential strain has been presented. We fabricate the fiber grating FP cavity sensor, and carry out the experiment on the measurement of absolute strain and differential strain. Experimental results verify the demodulation method, and show that this sensor has a good accuracy in the scope of measurement. The demodulating method can expand the number of multiplexed sensors combining with wavelength division multiplexing and time division multiplexing.

  2. Measured and parameterized energy fluxes estimated for Atlantic transects of RV Polarstern

    NASA Astrophysics Data System (ADS)

    Bumke, Karl; Macke, Andreas; Kalisch, John; Kleta, Henry

    2013-04-01

    Even to date energy fluxes over the oceans are difficult to assess. As an example the relative paucity of evaporation observations and the uncertainties of currently employed empirical approaches lead to large uncertainties of evaporation products over the ocean (e.g. Large and Yeager, 2009). Within the frame of OCEANET (Macke et al., 2010) we performed such measurements on Atlantic transects between Bremerhaven (Germany) and Cape Town (South Africa) or Punta Arenas (Chile) onboard RV Polarstern during the recent years. The basic measurements of sensible and latent heat fluxes are inertial-dissipation (e.g. Dupuis et al., 1997) flux estimates and measurements of the bulk variables. Turbulence measurements included a sonic anemometer and an infrared hygrometer, both mounted on the crow's nest. Mean meteorological sensors were those of the ship's operational measurement system. The global radiation and the down terrestrial radiation were measured on the OCEANET container placed on the monkey island. At least about 1000 time series of 1 h length were analyzed to derive bulk transfer coefficients for the fluxes of sensible and latent heat. The bulk transfer coefficients were applied to the ship's meteorological data to derive the heat fluxes at the sea surface. The reflected solar radiation was estimated from measured global radiation. The up terrestrial radiation was derived from the skin temperature according to the Stefan-Boltzmann law. Parameterized heat fluxes were compared to the widely used COARE-parameterization (Fairall et al., 2003), the agreement is excellent. Measured and parameterized heat and radiation fluxes gave the total energy budget at the air sea interface. As expected the mean total flux is positive, but there are also areas, where it is negative, indicating an energy loss of the ocean. It could be shown that the variations in the energy budget are mainly due to insolation and evaporation. A comparison between the mean values of measured and

  3. Ross filter development for absolute measurement of Al line radiation on MST

    NASA Astrophysics Data System (ADS)

    Lauersdorf, N.; Reusch, L. M.; den Hartog, D. J.; Goetz, J. A.; Franz, P.; Vanmeter, P.

    2017-10-01

    The MST has a two-color soft x-ray tomography (SXT) diagnostic that, using the double-filter technique, measures electron temperature (Te) from the slope of the soft x-ray (SXR) continuum. Because MST has an aluminum plasma-facing surface, bright Al line radiation occurs in the SXR spectrum. In past application of the double-filter technique, these lines have been filtered out using thick Be filters ( 400 μm and 800 μm), restricting the measurement temperature range to >=1 keV due to the signal strength having a positive correlation with Te. Another way to deal with the line radiation is to explicitly include it into the SXR spectrum analysis from which Te is derived. A Ross filter set has been designed to measure this line radiation, and will enable the absolute intensities of the aluminum lines to be quantified and incorporated into the analysis. The Ross filter will be used to measure Al+11 and Al+12 lines, occurring between 1.59 and 2.04 keV. By using multiple detectors with filters made of varying element concentrations, we create spectral bins in which the dominant transmission is the line radiation. Absolute measurement of Al line intensities will enable use of thinner filters in the SXT diagnostic and accurate measurement of Te < 1 keV. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Fusion Energy Sciences program under Award Numbers DE-FC02-05ER54814 and DE-SC0015474.

  4. MTR FAST NEUTRON FLUX MEASUREMENTS FOR CYCLE 146

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Weber, L D; Hogg, C H

    1962-03-20

    The fast neutron fluxes in selected positions of the MTR were measured for Cycle 146. The measurements were made at the beginning, throughout, and at the end of the cycle (564 Mwd). Vertical traverses for each position monitors are shown. (auth)

  5. A new measurement of the flux of the light cosmic-ray nuclei at high energies

    NASA Technical Reports Server (NTRS)

    Buckley, J.; Dwyer, J.; Mueller, D.; Swordy, S.; Tang, K. K.

    1994-01-01

    A new cosmic-ray detector utilizing a ring-imaging Cerenkov counter to determine the energy of light cosmic-ray nuclei was flown on high-altitude balloon from Fort Sumner, NM, in 1991 September. We describe the design and performance of this instrument and discuss the data analysis procedures. The measurement provides a new determination of the absolute flux and differential energy spectrum of the primary cosmic-ray species helium between 40 and 320 GeV/nucleon. The experiment also yields the spectra of carbon and oxygen and some information on the intensities of the secondary nuclei Li, Be, and B. A comparison between our results and previous measurements of heavier nuclei (Z greater than or equal to 4) from HEAO 3 and Spacelab 2 indicates good consistency between these measurements. The data set is compared with the results of a leaky box propagation model. We find good agreement with this model if the abundance of helium relative to oxygen at the source is taken to be 25 +/- 6 and if the source spectrum is given by a power law in energy proportional to E(exp -2.15).

  6. A flux-gradient system for simultaneous measurement of the CH4, CO2, and H2O fluxes at a lake-air interface.

    PubMed

    Xiao, Wei; Liu, Shoudong; Li, Hanchao; Xiao, Qitao; Wang, Wei; Hu, Zhenghua; Hu, Cheng; Gao, Yunqiu; Shen, Jing; Zhao, Xiaoyan; Zhang, Mi; Lee, Xuhui

    2014-12-16

    Inland lakes play important roles in water and greenhouse gas cycling in the environment. This study aims to test the performance of a flux-gradient system for simultaneous measurement of the fluxes of water vapor, CO2, and CH4 at a lake-air interface. The concentration gradients over the water surface were measured with an analyzer based on the wavelength-scanned cavity ring-down spectroscopy technology, and the eddy diffusivity was measured with a sonic anemometer. Results of a zero-gradient test indicate a flux measurement precision of 4.8 W m(-2) for water vapor, 0.010 mg m(-2) s(-1) for CO2, and 0.029 μg m(-2) s(-1) for CH4. During the 620 day measurement period, 97%, 69%, and 67% of H2O, CO2, and CH4 hourly fluxes were higher in magnitude than the measurement precision, which confirms that the flux-gradient system had adequate precision for the measurement of the lake-air exchanges. This study illustrates four strengths of the flux-gradient method: (1) the ability to simultaneously measure the flux of H2O, CO2, and CH4; (2) negligibly small density corrections; (3) the ability to resolve small CH4 gradient and flux; and (4) continuous and noninvasive operation. The annual mean CH4 flux (1.8 g CH4 m(-2) year(-1)) at this hypereutrophic lake was close to the median value for inland lakes in the world (1.6 g CH4 m(-2) year(-1)). The system has adequate precision for CH4 flux for broad applications but requires further improvement to resolve small CO2 flux in many lakes.

  7. Low-Power Dispersive Measurements of High-Coherence Flux Qubits

    NASA Astrophysics Data System (ADS)

    Hover, David; Sears, A. P.; Gudmundsen, T.; Kerman, A. J.; Welander, P. B.; Yoder, J. L.; Kamal, A.; Gustavsson, S.; Jin, X. Y.; Birenbaum, J.; Clarke, J.; Oliver, W. D.

    2014-03-01

    We report on progress towards nondestructive dispersive measurements of a high-coherence flux qubit. A capacitively shunted flux qubit that incorporates high-Q MBE aluminum will have longer relaxation and dephasing times when compared to a conventional flux qubit, while also maintaining the large anharmonicity necessary for complex gate operations. We numerically investigate the expected measurement fidelity of the improved qubit and present measurements that explore the boundary between destructive and nondestructive dispersive readout. This research was funded in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA); and by the Assistant Secretary of Defense for Research & Engineering under Air Force Contract number FA8721-05-C-0002. All statements of fact, opinion or conclusions contained herein are those of the authors and should not be construed as representing the official views or policies of IARPA, the ODNI, or the U.S. Government Present address: SLAC National Accelerator Laboratory, Menlo Park, CA.

  8. Quantitative comparison of in situ soil CO2 flux measurement methods

    Treesearch

    Jennifer D. Knoepp; James M. Vose

    2002-01-01

    Development of reliable regional or global carbon budgets requires accurate measurement of soil CO2 flux. We conducted laboratory and field studies to determine the accuracy and comparability of methods commonly used to measure in situ soil CO2 fluxes. Methods compared included CO2...

  9. High-frequency measurements of aeolian saltation flux: Field-based methodology and applications

    NASA Astrophysics Data System (ADS)

    Martin, Raleigh L.; Kok, Jasper F.; Hugenholtz, Chris H.; Barchyn, Thomas E.; Chamecki, Marcelo; Ellis, Jean T.

    2018-02-01

    Aeolian transport of sand and dust is driven by turbulent winds that fluctuate over a broad range of temporal and spatial scales. However, commonly used aeolian transport models do not explicitly account for such fluctuations, likely contributing to substantial discrepancies between models and measurements. Underlying this problem is the absence of accurate sand flux measurements at the short time scales at which wind speed fluctuates. Here, we draw on extensive field measurements of aeolian saltation to develop a methodology for generating high-frequency (up to 25 Hz) time series of total (vertically-integrated) saltation flux, namely by calibrating high-frequency (HF) particle counts to low-frequency (LF) flux measurements. The methodology follows four steps: (1) fit exponential curves to vertical profiles of saltation flux from LF saltation traps, (2) determine empirical calibration factors through comparison of LF exponential fits to HF number counts over concurrent time intervals, (3) apply these calibration factors to subsamples of the saltation count time series to obtain HF height-specific saltation fluxes, and (4) aggregate the calibrated HF height-specific saltation fluxes into estimates of total saltation fluxes. When coupled to high-frequency measurements of wind velocity, this methodology offers new opportunities for understanding how aeolian saltation dynamics respond to variability in driving winds over time scales from tens of milliseconds to days.

  10. Absolute Hugoniot measurements from a spherically convergent shock using x-ray radiography

    NASA Astrophysics Data System (ADS)

    Swift, Damian C.; Kritcher, Andrea L.; Hawreliak, James A.; Lazicki, Amy; MacPhee, Andrew; Bachmann, Benjamin; Döppner, Tilo; Nilsen, Joseph; Collins, Gilbert W.; Glenzer, Siegfried; Rothman, Stephen D.; Kraus, Dominik; Falcone, Roger W.

    2018-05-01

    The canonical high pressure equation of state measurement is to induce a shock wave in the sample material and measure two mechanical properties of the shocked material or shock wave. For accurate measurements, the experiment is normally designed to generate a planar shock which is as steady as possible in space and time, and a single state is measured. A converging shock strengthens as it propagates, so a range of shock pressures is induced in a single experiment. However, equation of state measurements must then account for spatial and temporal gradients. We have used x-ray radiography of spherically converging shocks to determine states along the shock Hugoniot. The radius-time history of the shock, and thus its speed, was measured by radiographing the position of the shock front as a function of time using an x-ray streak camera. The density profile of the shock was then inferred from the x-ray transmission at each instant of time. Simultaneous measurement of the density at the shock front and the shock speed determines an absolute mechanical Hugoniot state. The density profile was reconstructed using the known, unshocked density which strongly constrains the density jump at the shock front. The radiographic configuration and streak camera behavior were treated in detail to reduce systematic errors. Measurements were performed on the Omega and National Ignition Facility lasers, using a hohlraum to induce a spatially uniform drive over the outside of a solid, spherical sample and a laser-heated thermal plasma as an x-ray source for radiography. Absolute shock Hugoniot measurements were demonstrated for carbon-containing samples of different composition and initial density, up to temperatures at which K-shell ionization reduced the opacity behind the shock. Here we present the experimental method using measurements of polystyrene as an example.

  11. Estimating the absolute wealth of households.

    PubMed

    Hruschka, Daniel J; Gerkey, Drew; Hadley, Craig

    2015-07-01

    To estimate the absolute wealth of households using data from demographic and health surveys. We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. The median absolute wealth estimates of 1,403,186 households were 2056 international dollars per capita (interquartile range: 723-6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R(2)  = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality.

  12. Demonstrating the Error Budget for the Climate Absolute Radiance and Refractivity Observatory Through Solar Irradiance Measurements

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; McCorkel, Joel; McAndrew, Brendan

    2016-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe highaccuracy, long-term climate change trends and to use decadal change observations as a method to determine the accuracy of climate change. A CLARREO objective is to improve the accuracy of SI-traceable, absolute calibration at infrared and reflected solar wavelengths to reach on-orbit accuracies required to allow climate change observations to survive data gaps and observe climate change at the limit of natural variability. Such an effort will also demonstrate National Institute of Standards and Technology (NIST) approaches for use in future spaceborne instruments. The current work describes the results of laboratory and field measurements with the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. SOLARIS allows testing and evaluation of calibration approaches, alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a test-bed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. Results of laboratory calibration measurements are provided to demonstrate key assumptions about instrument behavior that are needed to achieve CLARREO's climate measurement requirements. Absolute radiometric response is determined using laser-based calibration sources and applied to direct solar views for comparison with accepted solar irradiance models to demonstrate accuracy values giving confidence in the error budget for the CLARREO reflectance retrieval.

  13. Absolute distance measurement with correction of air refractive index by using two-color dispersive interferometry.

    PubMed

    Wu, Hanzhong; Zhang, Fumin; Liu, Tingyang; Li, Jianshuang; Qu, Xinghua

    2016-10-17

    Two-color interferometry is powerful for the correction of the air refractive index especially in the turbulent air over long distance, since the empirical equations could introduce considerable measurement uncertainty if the environmental parameters cannot be measured with sufficient precision. In this paper, we demonstrate a method for absolute distance measurement with high-accuracy correction of air refractive index using two-color dispersive interferometry. The distances corresponding to the two wavelengths can be measured via the spectrograms captured by a CCD camera pair in real time. In the long-term experiment of the correction of air refractive index, the experimental results show a standard deviation of 3.3 × 10-8 for 12-h continuous measurement without the precise knowledge of the environmental conditions, while the variation of the air refractive index is about 2 × 10-6. In the case of absolute distance measurement, the comparison with the fringe counting interferometer shows an agreement within 2.5 μm in 12 m range.

  14. Volumetric vessel reconstruction method for absolute blood flow velocity measurement in Doppler OCT images

    NASA Astrophysics Data System (ADS)

    Qi, Li; Zhu, Jiang; Hancock, Aneeka M.; Dai, Cuixia; Zhang, Xuping; Frostig, Ron D.; Chen, Zhongping

    2017-02-01

    Doppler optical coherence tomography (DOCT) is considered one of the most promising functional imaging modalities for neuro biology research and has demonstrated the ability to quantify cerebral blood flow velocity at a high accuracy. However, the measurement of total absolute blood flow velocity (BFV) of major cerebral arteries is still a difficult problem since it not only relates to the properties of the laser and the scattering particles, but also relates to the geometry of both directions of the laser beam and the flow. In this paper, focusing on the analysis of cerebral hemodynamics, we presents a method to quantify the total absolute blood flow velocity in middle cerebral artery (MCA) based on volumetric vessel reconstruction from pure DOCT images. A modified region growing segmentation method is first used to localize the MCA on successive DOCT B-scan images. Vessel skeletonization, followed by an averaging gradient angle calculation method, is then carried out to obtain Doppler angles along the entire MCA. Once the Doppler angles are determined, the absolute blood flow velocity of each position on the MCA is easily found. Given a seed point position on the MCA, our approach could achieve automatic quantification of the fully distributed absolute BFV. Based on experiments conducted using a swept-source optical coherence tomography system, our approach could achieve automatic quantification of the fully distributed absolute BFV across different vessel branches in the rodent brain.

  15. A measurement of the absolute neutron beam polarization produced by an optically pumped 3He neutron spin filter

    NASA Astrophysics Data System (ADS)

    Rich, D. R.; Bowman, J. D.; Crawford, B. E.; Delheij, P. P. J.; Espy, M. A.; Haseyama, T.; Jones, G.; Keith, C. D.; Knudson, J.; Leuschner, M. B.; Masaike, A.; Masuda, Y.; Matsuda, Y.; Penttilä, S. I.; Pomeroy, V. R.; Smith, D. A.; Snow, W. M.; Szymanski, J. J.; Stephenson, S. L.; Thompson, A. K.; Yuan, V.

    2002-04-01

    The capability of performing accurate absolute measurements of neutron beam polarization opens a number of exciting opportunities in fundamental neutron physics and in neutron scattering. At the LANSCE pulsed neutron source we have measured the neutron beam polarization with an absolute accuracy of 0.3% in the neutron energy range from 40 meV to 10 eV using an optically pumped polarized 3He spin filter and a relative transmission measurement technique. 3He was polarized using the Rb spin-exchange method. We describe the measurement technique, present our results, and discuss some of the systematic effects associated with the method.

  16. Storage flux uncertainty impact on eddy covariance net ecosystem exchange measurements

    NASA Astrophysics Data System (ADS)

    Nicolini, Giacomo; Aubinet, Marc; Feigenwinter, Christian; Heinesch, Bernard; Lindroth, Anders; Mamadou, Ossénatou; Moderow, Uta; Mölder, Meelis; Montagnani, Leonardo; Rebmann, Corinna; Papale, Dario

    2017-04-01

    Complying with several assumption and simplifications, most of the carbon budget studies based on eddy covariance (EC) measurements, quantify the net ecosystem exchange (NEE) by summing the flux obtained by EC (Fc) and the storage flux (Sc). Sc is the rate of change of CO2, within the so called control volume below the EC measurement level, given by the difference in the instantaneous profiles of concentration at the beginning and end of the EC averaging period, divided by the averaging period. While cumulating over time led to a nullification of Sc, it can be significant at short time periods. The approaches used to estimate Sc fluxes largely vary, from measurements based only on a single sampling point (usually located at the EC measurement height) to measurements based on several sampling profiles distributed within the control volume. Furthermore, the number of sampling points within each profile vary, according to their height and the ecosystem typology. It follows that measurement accuracy increases with the sampling intensity within the control volume. In this work we use the experimental dataset collected during the ADVEX campaign in which Sc flux has been measured in three similar forest sites by the use of 5 sampling profiles (towers). Our main objective is to quantify the impact of Sc measurement uncertainty on NEE estimates. Results show that different methods may produce substantially different Sc flux estimates, with problematic consequences in case high frequency (half-hourly) data are needed for the analysis. However, the uncertainty on long-term estimates may be tolerate.

  17. Lunar eclipse photometry: absolute luminance measurements and modeling.

    PubMed

    Hernitschek, Nina; Schmidt, Elmar; Vollmer, Michael

    2008-12-01

    The Moon's time-dependent luminance was determined during the 9 February 1990 and 3 March 2007 total lunar eclipses by using calibrated, industry standard photometers. After the results were corrected to unit air mass and to standard distances for both Moon and Sun, an absolute calibration was accomplished by using the Sun's known luminance and a pre-eclipse lunar albedo of approximately 13.5%. The measured minimum level of brightness in the total phase of both eclipses was relatively high, namely -3.32 m(vis) and -1.7 m(vis), which hints at the absence of pronounced stratospheric aerosol. The light curves were modeled in such a way as to let the Moon move through an artificial Earth shadow composed of a multitude of disk and ring zones, containing a relative luminance data set from an atmospheric radiative transfer calculation.

  18. Multiple-Point Mass Flux Measurement System Using Rayleigh Scattering

    NASA Technical Reports Server (NTRS)

    Mielke, Amy F.; Elam, Kristie A.; Clem, Michelle M.

    2009-01-01

    A multiple-point Rayleigh scattering diagnostic is being developed to provide mass flux measurements in gas flows. Spectroscopic Rayleigh scattering is an established flow diagnostic that has the ability to provide simultaneous density, temperature, and velocity measurements. Rayleigh scattered light from a focused 18 Watt continuous-wave laser beam is directly imaged through a solid Fabry-Perot etalon onto a CCD detector which permits spectral analysis of the light. The spatial resolution of the measurements is governed by the locations of interference fringes, which can be changed by altering the etalon characteristics. A prototype system has been used to acquire data in a Mach 0.56 flow to demonstrate feasibility of using this system to provide mass flux measurements. Estimates of measurement uncertainty and recommendations for system improvements are presented

  19. Measurements of the Canonical Helicity Evolution of a Gyrating Kinked Flux Rope

    NASA Astrophysics Data System (ADS)

    von der Linden, J.; Sears, J.; Intrator, T.; You, S.

    2017-12-01

    Magnetic structures in the solar corona and planetary magnetospheres are often modelled as magnetic flux ropes governed by magnetohydrodynamics (MHD); however, inside these structures, as exhibited in reconnection, conversions between magnetic and kinetic energies occur over a wide range of scales. Flux ropes based on the flux of canonical momentum circulation extend the flux rope concept to include effects of finite particle momentum and present the distinct advantage of reconciling all plasma regimes - e.g. kinetic, two-fluid, and MHD - with the topological concept of helicity: twists, writhes, and linkages. This presentation shows the first visualization and analysis of the 3D dynamics of canonical flux ropes and their relative helicity evolution from laboratory measurements. Ion and electron canonical flux ropes are visualized from a dataset of Mach, triple, and Ḃ probe measurements at over 10,000 spatial locations of a gyrating kinked flux rope. The flux ropes co-gyrate with the peak density and electron temperature in and out of a measurement volume. The electron and ion canonical flux ropes twist with opposite handedness and the ion flux ropes writhe around the electron flux ropes. The relative cross helicity between the magnetic and ion flow vorticity flux ropes dominates the relative ion canonical helicity and is anti-correlated with the relative magnetic helicity. The 3D nature of the kink and a reverse eddy current affect the helicity evolution. This work is supported by DOE Grant DE-SC0010340 and the DOE Office of Science Graduate Student Research Program and prepared in part by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-735426

  20. Absolute Standard Hydrogen Electrode Potential Measured by Reduction of Aqueous Nanodrops in the Gas Phase

    PubMed Central

    Donald, William A.; Leib, Ryan D.; O'Brien, Jeremy T.; Bush, Matthew F.; Williams, Evan R.

    2008-01-01

    In solution, half-cell potentials are measured relative to those of other half cells, thereby establishing a ladder of thermochemical values that are referenced to the standard hydrogen electrode (SHE), which is arbitrarily assigned a value of exactly 0 V. Although there has been considerable interest in, and efforts toward, establishing an absolute electrochemical half-cell potential in solution, there is no general consensus regarding the best approach to obtain this value. Here, ion-electron recombination energies resulting from electron capture by gas-phase nanodrops containing individual [M(NH3)6]3+, M = Ru, Co, Os, Cr, and Ir, and Cu2+ ions are obtained from the number of water molecules that are lost from the reduced precursors. These experimental data combined with nanodrop solvation energies estimated from Born theory and solution-phase entropies estimated from limited experimental data provide absolute reduction energies for these redox couples in bulk aqueous solution. A key advantage of this approach is that solvent effects well past two solvent shells, that are difficult to model accurately, are included in these experimental measurements. By evaluating these data relative to known solution-phase reduction potentials, an absolute value for the SHE of 4.2 ± 0.4 V versus a free electron is obtained. Although not achieved here, the uncertainty of this method could potentially be reduced to below 0.1 V, making this an attractive method for establishing an absolute electrochemical scale that bridges solution and gas-phase redox chemistry. PMID:18288835

  1. High Accuracy, Absolute, Cryogenic Refractive Index Measurements of Infrared Lens Materials for JWST NIRCam using CHARMS

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas; Frey, Bradley

    2005-01-01

    The current refractive optical design of the James Webb Space Telescope (JWST) Near Infrared Camera (NIRCam) uses three infrared materials in its lenses: LiF, BaF2, and ZnSe. In order to provide the instrument s optical designers with accurate, heretofore unavailable data for absolute refractive index based on actual cryogenic measurements, two prismatic samples of each material were measured using the cryogenic, high accuracy, refraction measuring system (CHARMS) at NASA GSFC, densely covering the temperature range from 15 to 320 K and wavelength range from 0.4 to 5.6 microns. Measurement methods are discussed and graphical and tabulated data for absolute refractive index, dispersion, and thermo-optic coefficient for these three materials are presented along with estimates of uncertainty. Coefficients for second order polynomial fits of measured index to temperature are provided for many wavelengths to allow accurate interpolation of index to other wavelengths and temperatures.

  2. Estimating the absolute wealth of households

    PubMed Central

    Gerkey, Drew; Hadley, Craig

    2015-01-01

    Abstract Objective To estimate the absolute wealth of households using data from demographic and health surveys. Methods We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. Findings The median absolute wealth estimates of 1 403 186 households were 2056 international dollars per capita (interquartile range: 723–6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R2 = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Conclusion Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality. PMID:26170506

  3. Flux measurements of energy and trace gases in urban Houston, Texas

    NASA Astrophysics Data System (ADS)

    Boedeker, I.; Schade, G. W.; Adams, S.; Park, C.

    2008-12-01

    We describe the setup and some first year results of a new flux measurements tower in an urban area. An existing radio communications tower 4 km north of downtown Houston was equipped with micrometeorological instrumentation and trace gas sampling lines in spring 2007. Wind speed, temperature and relative humidity are recorded at five levels between 12 and 60 m above ground; 3-D wind speed measurements, solar and net radiances, and trace gas sampling are established from the 60 m level. A closed path IRGA is used for CO2 and water vapor fluxes, and independent instrumentation for criteria pollutant and VOC fluxes. Two CSI data loggers and software control the measurements, and EdiRe software is used to analyze turbulence data and compute fluxes. A project description is provided at http://atmo.tamu.edu/yellowcabtower. Surface properties as calculated from the gradient measurements show the site to be surprisingly uniform, with displacement heights between 5 and 9 m and roughness lengths between 0.4 and 0.7 m, despite urban heterogeneity. The latter is investigated through visible/near IR orthoimagery and LIDAR data, which are incorporated into a local GIS. Net radiation was also only marginally affected by surface heterogeneity. At this urban location it is balanced by roughly equal amounts of sensible heat, latent heat, and storage fluxes. Latent heat flux, however, is smaller outside the growing season, with an equivalent increase in winter storage fluxes, as expected. Significant differences are also observed with direction during summer, showing decreased Bowen ratios and lower CO2 emissions from sectors with a larger urban tree canopy cover in the footprint. The largely mature, dominantly oak urban canopy cover alleviates approximately 100 W m- 2 during typical summer days. On the other hand, anthropogenic CO2 emissions dominate over photosynthetic uptake all year round. Measured carbon fluxes peak during morning rush-hour traffic, especially when increasing

  4. Absolute measurement of hadronic branching fractions of the Ds+ meson.

    PubMed

    Alexander, J P; Berkelman, K; Cassel, D G; Duboscq, J E; Ehrlich, R; Fields, L; Gibbons, L; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Jones, C D; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Mahlke-Krüger, H; Mohapatra, D; Onyisi, P U E; Patterson, J R; Peterson, D; Riley, D; Ryd, A; Sadoff, A J; Shi, X; Stroiney, S; Sun, W M; Wilksen, T; Athar, S B; Patel, R; Yelton, J; Rubin, P; Eisenstein, B I; Karliner, I; Mehrabyan, S; Lowrey, N; Selen, M; White, E J; Wiss, J; Mitchell, R E; Shepherd, M R; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Hietala, J; Kubota, Y; Klein, T; Lang, B W; Poling, R; Scott, A W; Zweber, P; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Libby, J; Powell, A; Wilkinson, G; Ecklund, K M; Love, W; Savinov, V; Lopez, A; Mendez, H; Ramirez, J; Ge, J Y; Miller, D H; Sanghi, B; Shipsey, I P J; Xin, B; Adams, G S; Anderson, M; Cummings, J P; Danko, I; Hu, D; Moziak, B; Napolitano, J; He, Q; Insler, J; Muramatsu, H; Park, C S; Thorndike, E H; Yang, F; Artuso, M; Blusk, S; Khalil, S; Li, J; Mountain, R; Nisar, S; Randrianarivony, K; Sultana, N; Skwarnicki, T; Stone, S; Wang, J C; Zhang, L M; Bonvicini, G; Cinabro, D; Dubrovin, M; Lincoln, A; Rademacker, J; Asner, D M; Edwards, K W; Naik, P; Briere, R A; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L

    2008-04-25

    The branching fractions of D(s)(+/-) meson decays serve to normalize many measurements of processes involving charm quarks. Using 298 pb(-1) of e(+)e(-) collisions recorded at a center of mass energy of 4.17 GeV, we determine absolute branching fractions for eight D(s)(+/-) decays with a double tag technique. In particular we determine the branching fraction B(D(s)(+)-->K(-)K(+}pi(+))=(5.50+/-0.23+/-0.16)%, where the uncertainties are statistical and systematic, respectively. We also provide partial branching fractions for kinematic subsets of the K(-)K(+)pi(+) decay mode.

  5. Absolute Measurement of Hadronic Branching Fractions of the Ds+ Meson

    NASA Astrophysics Data System (ADS)

    Alexander, J. P.; Berkelman, K.; Cassel, D. G.; Duboscq, J. E.; Ehrlich, R.; Fields, L.; Gibbons, L.; Gray, R.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hertz, D.; Jones, C. D.; Kandaswamy, J.; Kreinick, D. L.; Kuznetsov, V. E.; Mahlke-Krüger, H.; Mohapatra, D.; Onyisi, P. U. E.; Patterson, J. R.; Peterson, D.; Riley, D.; Ryd, A.; Sadoff, A. J.; Shi, X.; Stroiney, S.; Sun, W. M.; Wilksen, T.; Athar, S. B.; Patel, R.; Yelton, J.; Rubin, P.; Eisenstein, B. I.; Karliner, I.; Mehrabyan, S.; Lowrey, N.; Selen, M.; White, E. J.; Wiss, J.; Mitchell, R. E.; Shepherd, M. R.; Besson, D.; Pedlar, T. K.; Cronin-Hennessy, D.; Gao, K. Y.; Hietala, J.; Kubota, Y.; Klein, T.; Lang, B. W.; Poling, R.; Scott, A. W.; Zweber, P.; Dobbs, S.; Metreveli, Z.; Seth, K. K.; Tomaradze, A.; Libby, J.; Powell, A.; Wilkinson, G.; Ecklund, K. M.; Love, W.; Savinov, V.; Lopez, A.; Mendez, H.; Ramirez, J.; Ge, J. Y.; Miller, D. H.; Sanghi, B.; Shipsey, I. P. J.; Xin, B.; Adams, G. S.; Anderson, M.; Cummings, J. P.; Danko, I.; Hu, D.; Moziak, B.; Napolitano, J.; He, Q.; Insler, J.; Muramatsu, H.; Park, C. S.; Thorndike, E. H.; Yang, F.; Artuso, M.; Blusk, S.; Khalil, S.; Li, J.; Mountain, R.; Nisar, S.; Randrianarivony, K.; Sultana, N.; Skwarnicki, T.; Stone, S.; Wang, J. C.; Zhang, L. M.; Bonvicini, G.; Cinabro, D.; Dubrovin, M.; Lincoln, A.; Rademacker, J.; Asner, D. M.; Edwards, K. W.; Naik, P.; Briere, R. A.; Ferguson, T.; Tatishvili, G.; Vogel, H.; Watkins, M. E.; Rosner, J. L.

    2008-04-01

    The branching fractions of Ds± meson decays serve to normalize many measurements of processes involving charm quarks. Using 298pb-1 of e+e- collisions recorded at a center of mass energy of 4.17 GeV, we determine absolute branching fractions for eight Ds± decays with a double tag technique. In particular we determine the branching fraction B(Ds+→K-K+π+)=(5.50±0.23±0.16)%, where the uncertainties are statistical and systematic, respectively. We also provide partial branching fractions for kinematic subsets of the K-K+π+ decay mode.

  6. Analysis of field measurements of carbon dioxide and water vapor fluxes

    NASA Technical Reports Server (NTRS)

    Verma, Shashi B.

    1991-01-01

    Analysis of the field measurements of carbon dioxide and water vapor fluxes is discussed. These data were examined in conjunction with reflectance obtained from helicopter mounted Modular Multiband Radiometer. These measurements are representative of the canopy scale (10 to 100 m)(exp 2) and provide a good basis for investigating the hypotheses/relationship potentially useful in remote sensing applications. All the micrometeorological data collected during FIFE-89 were processed and fluxes of CO2, water vapor, and sensible heat were calculated. Soil CO2 fluxes were also estimated. Employing these soil CO2 flux values, in conjunction with micrometeorological measurements, canopy photosynthesis is being estimated. A biochemical model of leaf photosynthesis was adapted to the prairie vegetation. The modeled leaf photosynthesis rates were scaled up to the canopy level. This model and a multiplicative stomatal conductance model are also used to calculate canopy conductance.

  7. Measurement of Solar pp-neutrino flux with Borexino: results and implications

    NASA Astrophysics Data System (ADS)

    Smirnov, O. Yu; Agostini, M.; Appel, S.; Bellini, G.; Benziger, J.; Bick, D.; Bonfini, G.; Bravo, D.; Caccianiga, B.; Calaprice, F.; Caminata, A.; Cavalcante, P.; Chepurnov, A.; D'Angelo, D.; Davini, S.; Derbin, A.; Di Noto, L.; Drachnev, I.; Etenko, A.; Fomenko, K.; Franco, D.; Gabriele, F.; Galbiati, C.; Ghiano, C.; Giammarchi, M.; Goeger-Neff, M.; Goretti, A.; Gromov, M.; Hagner, C.; Hungerford, E.; Ianni, Aldo; Ianni, Andrea; Jedrzejczak, K.; Kaiser, M.; Kobychev, V.; Korablev, D.; Korga, G.; Kryn, D.; Laubenstein, M.; Lehnert, B.; Litvinovich, E.; Lombardi, F.; Lombardi, P.; Ludhova, L.; Lukyanchenko, G.; Machulin, O.; Manecki, S.; Maneschg, W.; Marcocci, S.; Meroni, E.; Meyer, M.; Miramonti, L.; Misiaszek, M.; Montuschi, M.; Mosteiro, P.; Muratova, V.; Neumair, B.; Oberauer, L.; Obolensky, M.; Ortica, F.; Pallavicini, M.; Papp, L.; Perasso, L.; Pocar, A.; Ranucci, G.; Razeto, A.; Re, A.; Romani, A.; Roncin, R.; Rossi, N.; Schönert, S.; Semenov, D.; Simgen, H.; Skorokhvatov, M.; Sotnikov, A.; Sukhotin, S.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Thurn, J.; Toropova, M.; Unzhakov, E.; Vishneva, A.; Vogelaar, R. B.; von Feilitzsch, F.; Wang, H.; Weinz, S.; Winter, J.; Wojcik, M.; Wurm, M.; Yokley, Z.; Zaimidoroga, O.; Zavatarelli, S.; Zuber, K.; Zuzel, G.

    2016-02-01

    Measurement of the Solar pp-neutrino flux completed the measurement of Solar neutrino fluxes from the pp-chain of reactions in Borexino experiment. The result is in agreement with the prediction of the Standard Solar Model and the MSW/LMA oscillation scenario. A comparison of the total neutrino flux from the Sun with Solar luminosity in photons provides a test of the stability of the Sun on the 105 years time scale, and sets a strong limit on the power production by the unknown energy sources in the Sun.

  8. Comparison of heat flux measurement techniques during the DIII-D metal ring campaign

    NASA Astrophysics Data System (ADS)

    Barton, J. L.; Nygren, R. E.; Unterberg, E. A.; Watkins, J. G.; Makowski, M. A.; Moser, A.; Rudakov, D. L.; Buchenauer, D.

    2017-12-01

    The heat fluxes expected in the ITER divertor raise concerns about the damage tolerances of tungsten, especially due to thermal transients caused by edge localized modes (ELMs) as well as frequent temperature cycling from high to low extremes. Therefore we are motivated to understand the heat flux conditions that can cause not only enhanced erosion but also bulk thermo-mechanical damage to a tungsten divertor. For the metal ring campaign in DIII-D, tungsten-coated TZM tile inserts were installed making two toroidal arrays of metal tile inserts in the lower divertor. This study examines the deposited heat flux on these rings with embedded thermocouples (TCs) sampling at 10 kHz and compares them to Langmuir probe (LP) and infrared thermography (IRTV) heat flux measurements. We see agreement of the TC, LP, and IRTV data within 20% of the heat flux averaged over the entire discharge, and that all three diagnostics suggest parallel heat flux at the OSP location increases linearly with input heating power. The TC and LP heat flux time traces during the discharge trend together during large changes to the average heat flux. By subtracting the LP measured inter-ELM heat flux from TC data, using a rectangular ELM energy pulse shape, and taking the relative size and duration of each ELM from {{D}}α measurements, we extract the ELM heat fluxes from TC data. This over-estimates the IRTV measured ELM heat fluxes by a factor of 1.9, and could be due to the simplicity of the TC heat flux model and the assumed ELM energy pulse shape. ELM heat fluxes deposited on the inserts are used to model tungsten erosion in this campaign. These TC ELM heat flux estimates are used in addition to IRTV, especially in cases where the IRTV view to the metal ring is obstructed. We observe that some metal inserts were deformed due to exposed leading edges. The thermal conditions on these inserts are investigated with the thermal modeling code ABAQUS using our heat flux measurements when these edges

  9. Plasma momentum meter for momentum flux measurements

    DOEpatents

    Zonca, Fulvio; Cohen, Samuel A.; Bennett, Timothy; Timberlake, John R.

    1993-01-01

    Invention comprises an instrument in which momentum flux onto a biasable target plate is transferred via a suspended quartz tube onto a sensitive force transducer--a capacitance-type pressure gauge. The transducer is protected from thermal damage, arcing and sputtering, and materials used in the target and pendulum are electrically insulating, rigid even at elevated temperatures, and have low thermal conductivity. The instrument enables measurement of small forces (10.sup.-5 to 10.sup.3 N) accompanied by high heat fluxes which are transmitted by energetic particles with 10's of eV of kinetic energy in a intense magnetic field and pulsed plasma environment.

  10. Eddy covariance measurements of methane fluxes over grazed native and improved prairies in Oklahoma

    USDA-ARS?s Scientific Manuscript database

    Although several studies have reported eddy covariance (EC) measurements at several tallgrass prairie sites to investigate the dynamics of carbon and water vapor fluxes, the EC measurements of methane (CH4) fluxes over grazed tallgrass prairie sites are lacking. CH4 fluxes were measured during the 2...

  11. A digital, constant-frequency pulsed phase-locked-loop instrument for real-time, absolute ultrasonic phase measurements

    NASA Astrophysics Data System (ADS)

    Haldren, H. A.; Perey, D. F.; Yost, W. T.; Cramer, K. E.; Gupta, M. C.

    2018-05-01

    A digitally controlled instrument for conducting single-frequency and swept-frequency ultrasonic phase measurements has been developed based on a constant-frequency pulsed phase-locked-loop (CFPPLL) design. This instrument uses a pair of direct digital synthesizers to generate an ultrasonically transceived tone-burst and an internal reference wave for phase comparison. Real-time, constant-frequency phase tracking in an interrogated specimen is possible with a resolution of 0.000 38 rad (0.022°), and swept-frequency phase measurements can be obtained. Using phase measurements, an absolute thickness in borosilicate glass is presented to show the instrument's efficacy, and these results are compared to conventional ultrasonic pulse-echo time-of-flight (ToF) measurements. The newly developed instrument predicted the thickness with a mean error of -0.04 μm and a standard deviation of error of 1.35 μm. Additionally, the CFPPLL instrument shows a lower measured phase error in the absence of changing temperature and couplant thickness than high-resolution cross-correlation ToF measurements at a similar signal-to-noise ratio. By showing higher accuracy and precision than conventional pulse-echo ToF measurements and lower phase errors than cross-correlation ToF measurements, the new digitally controlled CFPPLL instrument provides high-resolution absolute ultrasonic velocity or path-length measurements in solids or liquids, as well as tracking of material property changes with high sensitivity. The ability to obtain absolute phase measurements allows for many new applications than possible with previous ultrasonic pulsed phase-locked loop instruments. In addition to improved resolution, swept-frequency phase measurements add useful capability in measuring properties of layered structures, such as bonded joints, or materials which exhibit non-linear frequency-dependent behavior, such as dispersive media.

  12. Absolute measurement of the Hugoniot and sound velocity of liquid copper at multimegabar pressures

    DOE PAGES

    McCoy, Chad August; Knudson, Marcus David; Root, Seth

    2017-11-13

    Measurement of the Hugoniot and sound velocity provides information on the bulk modulus and Grüneisen parameter of a material at extreme conditions. The capability to launch multilayered (copper/aluminum) flyer plates at velocities in excess of 20 km/s with the Sandia Z accelerator has enabled high-precision sound-velocity measurements at previously inaccessible pressures. For these experiments, the sound velocity of the copper flyer must be accurately known in the multi-Mbar regime. Here we describe the development of copper as an absolutely calibrated sound-velocity standard for high-precision measurements at pressures in excess of 400 GPa. Using multilayered flyer plates, we performed absolute measurementsmore » of the Hugoniot and sound velocity of copper for pressures from 500 to 1200 GPa. These measurements enabled the determination of the Grüneisen parameter for dense liquid copper, clearly showing a density dependence above the melt transition. As a result, combined with earlier data at lower pressures, these results constrain the sound velocity as a function of pressure, enabling the use of copper as a Hugoniot and sound-velocity standard for pressures up to 1200 GPa.« less

  13. Absolute measurement of the Hugoniot and sound velocity of liquid copper at multimegabar pressures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McCoy, Chad August; Knudson, Marcus David; Root, Seth

    Measurement of the Hugoniot and sound velocity provides information on the bulk modulus and Grüneisen parameter of a material at extreme conditions. The capability to launch multilayered (copper/aluminum) flyer plates at velocities in excess of 20 km/s with the Sandia Z accelerator has enabled high-precision sound-velocity measurements at previously inaccessible pressures. For these experiments, the sound velocity of the copper flyer must be accurately known in the multi-Mbar regime. Here we describe the development of copper as an absolutely calibrated sound-velocity standard for high-precision measurements at pressures in excess of 400 GPa. Using multilayered flyer plates, we performed absolute measurementsmore » of the Hugoniot and sound velocity of copper for pressures from 500 to 1200 GPa. These measurements enabled the determination of the Grüneisen parameter for dense liquid copper, clearly showing a density dependence above the melt transition. As a result, combined with earlier data at lower pressures, these results constrain the sound velocity as a function of pressure, enabling the use of copper as a Hugoniot and sound-velocity standard for pressures up to 1200 GPa.« less

  14. Flux Tower Eddy Covariance and Meteorological Measurements for Barrow, Alaska: 2012-2016

    DOE Data Explorer

    Dengel, Sigrid; Torn, Margaret; Billesbach, David

    2017-08-24

    The dataset contains half-hourly eddy covariance flux measurements and determinations, companion meteorological measurements, and ancillary data from the flux tower (US-NGB) on the Barrow Environmental Observatory at Barrow (Utqiagvik), Alaska for the period 2012 through 2016. Data have been processed using EddyPro software and screened by the contributor. The flux tower sits in an Arctic coastal tundra ecosystem. This dataset updates a previous dataset by reprocessing a longer period of record in the same manner. Related dataset "Eddy-Covariance and auxiliary measurements, NGEE-Barrow, 2012-2013" DOI:10.5440/1124200.

  15. Multi-spectra Cosmic Ray Flux Measurement

    NASA Astrophysics Data System (ADS)

    He, Xiaochun; Dayananda, Mathes

    2010-02-01

    The Earth's upper atmosphere is constantly bombarded by rain of charged particles known as primary cosmic rays. These primary cosmic rays will collide with the atmospheric molecules and create extensive secondary particles which shower downward to the surface of the Earth. In recent years, a few studies have been done regarding to the applications of the cosmic ray measurements and the correlations between the Earth's climate conditions and the cosmic ray fluxes [1,2,3]. Most of the particles, which reach to the surface of the Earth, are muons together with a small percentage of electrons, gammas, neutrons, etc. At Georgia State University, multiple cosmic ray particle detectors have been constructed to measure the fluxes and energy distributions of the secondary cosmic ray particles. In this presentation, we will briefly describe these prototype detectors and show the preliminary test results. Reference: [1] K.Borozdin, G.Hogan, C.Morris, W.Priedhorsky, A.Saunders, L.Shultz, M.Teasdale, Nature, Vol.422, 277 (2003). [2] L.V. Egorova, V. Ya Vovk, O.A. Troshichev, Journal of Atmospheric and Terrestrial Physics 62, 955-966 (2000). [3] Henrik Svensmark, Phy. Rev. Lett. 81, 5027 (1998). )

  16. Adsorption calorimetry during metal vapor deposition on single crystal surfaces: Increased flux, reduced optical radiation, and real-time flux and reflectivity measurements

    NASA Astrophysics Data System (ADS)

    Sellers, Jason R. V.; James, Trevor E.; Hemmingson, Stephanie L.; Farmer, Jason A.; Campbell, Charles T.

    2013-12-01

    Thin films of metals and other materials are often grown by physical vapor deposition. To understand such processes, it is desirable to measure the adsorption energy of the deposited species as the film grows, especially when grown on single crystal substrates where the structure of the adsorbed species, evolving interface, and thin film are more homogeneous and well-defined in structure. Our group previously described in this journal an adsorption calorimeter capable of such measurements on single-crystal surfaces under the clean conditions of ultrahigh vacuum [J. T. Stuckless, N. A. Frei, and C. T. Campbell, Rev. Sci. Instrum. 69, 2427 (1998)]. Here we describe several improvements to that original design that allow for heat measurements with ˜18-fold smaller standard deviation, greater absolute accuracy in energy calibration, and, most importantly, measurements of the adsorption of lower vapor-pressure materials which would have previously been impossible. These improvements are accomplished by: (1) using an electron beam evaporator instead of a Knudsen cell to generate the metal vapor at the source of the pulsed atomic beam, (2) changing the atomic beam design to decrease the relative amount of optical radiation that accompanies evaporation, (3) adding an off-axis quartz crystal microbalance for real-time measurement of the flux of the atomic beam during calorimetry experiments, and (4) adding capabilities for in situ relative diffuse optical reflectivity determinations (necessary for heat signal calibration). These improvements are not limited to adsorption calorimetry during metal deposition, but also could be applied to better study film growth of other elements and even molecular adsorbates.

  17. Adsorption calorimetry during metal vapor deposition on single crystal surfaces: increased flux, reduced optical radiation, and real-time flux and reflectivity measurements.

    PubMed

    Sellers, Jason R V; James, Trevor E; Hemmingson, Stephanie L; Farmer, Jason A; Campbell, Charles T

    2013-12-01

    Thin films of metals and other materials are often grown by physical vapor deposition. To understand such processes, it is desirable to measure the adsorption energy of the deposited species as the film grows, especially when grown on single crystal substrates where the structure of the adsorbed species, evolving interface, and thin film are more homogeneous and well-defined in structure. Our group previously described in this journal an adsorption calorimeter capable of such measurements on single-crystal surfaces under the clean conditions of ultrahigh vacuum [J. T. Stuckless, N. A. Frei, and C. T. Campbell, Rev. Sci. Instrum. 69, 2427 (1998)]. Here we describe several improvements to that original design that allow for heat measurements with ~18-fold smaller standard deviation, greater absolute accuracy in energy calibration, and, most importantly, measurements of the adsorption of lower vapor-pressure materials which would have previously been impossible. These improvements are accomplished by: (1) using an electron beam evaporator instead of a Knudsen cell to generate the metal vapor at the source of the pulsed atomic beam, (2) changing the atomic beam design to decrease the relative amount of optical radiation that accompanies evaporation, (3) adding an off-axis quartz crystal microbalance for real-time measurement of the flux of the atomic beam during calorimetry experiments, and (4) adding capabilities for in situ relative diffuse optical reflectivity determinations (necessary for heat signal calibration). These improvements are not limited to adsorption calorimetry during metal deposition, but also could be applied to better study film growth of other elements and even molecular adsorbates.

  18. Absolute measurement of undulator radiation in the extreme ultraviolet

    NASA Astrophysics Data System (ADS)

    Maezawa, H.; Mitani, S.; Suzuki, Y.; Kanamori, H.; Tamamushi, S.; Mikuni, A.; Kitamura, H.; Sasaki, T.

    1983-04-01

    The spectral brightness of undulator radiation emitted by the model PMU-1 incorporated in the SOR-RING, the dedicated synchrotron radiation source in Tokyo, has been studied in the extreme ultraviolet region from 21.6 to 72.9 eV as a function of the electron energy γ, the field parameter K, and the angle of observation ϴ in the absolute scale. A series of measurements covering the first and the second harmonic component of undulator radiation was compared with the fundamental formula λ n= {λ 0}/{2nγ 2}( {1+K 2}/{2}+γϴ 2 and the effects of finite emittance were studied. The brightness at the first peak was smaller than the theoretical value, while an enhanced second harmonic component was observed.

  19. Mean and turbulent mass flux measurements in an idealised street network.

    PubMed

    Carpentieri, Matteo; Robins, Alan G; Hayden, Paul; Santi, Edoardo

    2018-03-01

    Pollutant mass fluxes are rarely measured in the laboratory, especially their turbulent component. They play a major role in the dispersion of gases in urban areas and modern mathematical models often attempt some sort of parametrisation. An experimental technique to measure mean and turbulent fluxes in an idealised urban array was developed and applied to improve our understanding of how the fluxes are distributed in a dense street canyon network. As expected, horizontal advective scalar fluxes were found to be dominant compared with the turbulent components. This is an important result because it reduces the complexity in developing parametrisations for street network models. On the other hand, vertical mean and turbulent fluxes appear to be approximately of the same order of magnitude. Building height variability does not appear to affect the exchange process significantly, while the presence of isolated taller buildings upwind of the area of interest does. One of the most interesting results, again, is the fact that even very simple and regular geometries lead to complex advective patterns at intersections: parametrisations derived from measurements in simpler geometries are unlikely to capture the full complexity of a real urban area. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Measuring the absolute deuterium-tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF.

    PubMed

    Casey, D T; Frenje, J A; Gatu Johnson, M; Séguin, F H; Li, C K; Petrasso, R D; Glebov, V Yu; Katz, J; Knauer, J P; Meyerhofer, D D; Sangster, T C; Bionta, R M; Bleuel, D L; Döppner, T; Glenzer, S; Hartouni, E; Hatchett, S P; Le Pape, S; Ma, T; MacKinnon, A; McKernan, M A; Moran, M; Moses, E; Park, H-S; Ralph, J; Remington, B A; Smalyuk, V; Yeamans, C B; Kline, J; Kyrala, G; Chandler, G A; Leeper, R J; Ruiz, C L; Cooper, G W; Nelson, A J; Fletcher, K; Kilkenny, J; Farrell, M; Jasion, D; Paguio, R

    2012-10-01

    A magnetic recoil spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

  1. Seasonality of Overstory and Understory Fluxes in a Semi-Arid Oak Savanna: What can be Learned from Comparing Measured and Modeled Fluxes?

    NASA Astrophysics Data System (ADS)

    Raz-Yaseef, N.; Sonnentag, O.; Kobayashi, H.; Chen, J. M.; Verfaillie, J. G.; Ma, S.; Baldocchi, D. D.

    2011-12-01

    Semi-arid climates experience large seasonal and inter-annual variability in radiation and precipitation, creating natural conditions adequate to study how year-to-year changes affect atmosphere-biosphere fluxes. Especially, savanna ecosystems, that combine tree and below-canopy components, create a unique environment in which phenology dramatically changes between seasons. We used a 10-year flux database in order to define seasonal and interannual variability of climatic inputs and fluxes, and evaluate model capability to reproduce observed variability. This is based on the perception that model capability to construct the deviation, and not the average, is important in order to correctly predict ecosystem sensitivity to climate change. Our research site is a low density and low LAI (0.8) semi-arid savanna, located at Tonzi Ranch, Northern California. In this system, trees are active during the warm season (Mar - Oct), and grasses are active during the wet season (Dec - May). Measurements of carbon and water fluxes above and below the tree canopy using eddy covariance and supplementary measurements have been made since 2001. Fluxes were simulated using bio-meteorological process-oriented ecosystem models: BEPS and 3D-CAONAK. Models were partly capable of reproducing fluxes on daily scales (R2=0.66). We then compared model outputs for different ecosystem components and seasons, and found distinct seasons with high correlations while other seasons were purely represented. Comparison was much higher for ET than for GPP. The understory was better simulated than the overstory. CANOAK overestimated spring understory fluxes, probably due to the capability to directly calculated 3D radiative transfer. BEPS underestimated spring understory fluxes, following the pre-description of grass die-off. Both models underestimated peak spring overstory fluxes. During winter tree dormant, modeled fluxes were null, but occasional high fluxes of both ET and GPP were measured following

  2. Experimental feasibility of the airborne measurement of absolute oil fluorescence spectral conversion efficiency

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Swift, R. N.

    1983-01-01

    Airborne lidar oil spill experiments carried out to determine the practicability of the AOFSCE (absolute oil fluorescence spectral conversion efficiency) computational model are described. The results reveal that the model is suitable over a considerable range of oil film thicknesses provided the fluorescence efficiency of the oil does not approach the minimum detection sensitivity limitations of the lidar system. Separate airborne lidar experiments to demonstrate measurement of the water column Raman conversion efficiency are also conducted to ascertain the ultimate feasibility of converting such relative oil fluorescence to absolute values. Whereas the AOFSCE model is seen as highly promising, further airborne water column Raman conversion efficiency experiments with improved temporal or depth-resolved waveform calibration and software deconvolution techniques are thought necessary for a final determination of suitability.

  3. Eddy covariance N2O flux measurements at low flux rates: results from the InGOS campaign in a Danish willow field.

    NASA Astrophysics Data System (ADS)

    Ibrom, Andreas; Brümmer, Christian; Hensen, Arjan; van Asperen, Hella; Carter, Mette S.; Gasche, Rainer; Famulari, Daniela; Kutsch, Werner; Pilegaard, Kim; Ambus, Per

    2014-05-01

    Nitrous oxide (N2O) fluxes from soils are characterised by their high spatial and temporal variability. The fluxes depend on the availability of the substrates for nitrification and denitrification and soil physical and chemical conditions that control the metabolic microbial activity. The sporadic nature of the fluxes and their high sensitivity to alterations of the soil climate put very high demands on measurement approaches. Laser spectroscopy enables accurate and fast response detection of atmospheric N2O concentrations and is used for eddy covariance (EC) flux measurements. Alternatively N2O fluxes can be measured with chambers together with high precision analysers. Differences in the measurement approaches and system designs are expected to have a considerable influence on the accuracy of the flux estimation. This study investigates how three different eddy covariance systems perform in a situation of low N2O fluxes from a flat surface. Chamber flux measurements with differing chamber and analyser designs are used for comparison. In April 2013, the EU research infrastructure project InGOS (http://www.ingos-infrastructure.eu/) organised a campaign of N2O flux measurements in a willow plantation close to the Risø Campus of the Technical University of Denmark. The willow field was harvested in February 2013 and received mineral fertiliser equivalent to 120 kg N ha-1 before the campaign started. Three different eddy covariance systems took part in the campaign: two Aerodyne quantum cascade laser (QCL) based systems and one Los Gatos Research off-axis integrated-cavity-output spectroscopy (ICOS) system for N2O and CO. The sonic anemometers were all installed at 2 m height above the bare ground. Gill R3 type sonic anemometers were used with QCL systems and a Gil HS-50 with the ICOS system. The 10 Hz raw data were analysed with group specific softwares and procedures. The local conditions in the exceptionally cold and dry spring 2013 did not lead to large N2O flux

  4. Measuring Socioeconomic Inequalities With Predicted Absolute Incomes Rather Than Wealth Quintiles: A Comparative Assessment Using Child Stunting Data From National Surveys.

    PubMed

    Fink, Günther; Victora, Cesar G; Harttgen, Kenneth; Vollmer, Sebastian; Vidaletti, Luís Paulo; Barros, Aluisio J D

    2017-04-01

    To compare the predictive power of synthetic absolute income measures with that of asset-based wealth quintiles in low- and middle-income countries (LMICs) using child stunting as an outcome. We pooled data from 239 nationally representative household surveys from LMICs and computed absolute incomes in US dollars based on households' asset rank as well as data on national consumption and inequality levels. We used multivariable regression models to compare the predictive power of the created income measure with the predictive power of existing asset indicator measures. In cross-country analysis, log absolute income predicted 54.5% of stunting variation observed, compared with 20% of variation explained by wealth quintiles. For within-survey analysis, we also found absolute income gaps to be predictive of the gaps between stunting in the wealthiest and poorest households (P < .001). Our results suggest that absolute income levels can greatly improve the prediction of stunting levels across and within countries over time, compared with models that rely solely on relative wealth quintiles.

  5. Absolute stellar photometry on moderate-resolution FPA images

    USGS Publications Warehouse

    Stone, T.C.

    2009-01-01

    An extensive database of star (and Moon) images has been collected by the ground-based RObotic Lunar Observatory (ROLO) as part of the US Geological Survey program for lunar calibration. The stellar data are used to derive nightly atmospheric corrections for the observations from extinction measurements, and absolute calibration of the ROLO sensors is based on observations of Vega and published reference flux and spectrum data. The ROLO telescopes were designed for imaging the Moon at moderate resolution, thus imposing some limitations for the stellar photometry. Attaining accurate stellar photometry with the ROLO image data has required development of specialized processing techniques. A key consideration is consistency in discriminating the star core signal from the off-axis point spread function. The analysis and processing methods applied to the ROLO stellar image database are described. ?? 2009 BIPM and IOP Publishing Ltd.

  6. Aerosol Fluxes over Amazon Rain Forest Measured with the Eddy Covariance Method

    NASA Astrophysics Data System (ADS)

    Ahlm, L.; Nilsson, E. D.; Krejci, R.; Mårtensson, E. M.; Vogt, M.; Artaxo, P.

    2008-12-01

    We present measurements of vertical aerosol fluxes over the Amazon carried out on top of K34, a 50 meter high tower in the Cuieiras Reserve about 50 km north of Manaus in northern Brazil. The turbulent fluxes were measured with the eddy covariance method. The covariance of vertical wind speed from a sonic anemometer Gill Windmaster and total aerosol number concentration from a condensation particle counter (CPC) TSI 3010 provided the total number flux (diameter >0.01 μm). The covariance of vertical wind speed and size resolved number concentrations from an optical particle counter (OPC) Grimm 1.109 provided size resolved number fluxes in 15 bins from 0.25 μm to 2.5 μm diameter. Additionally fluxes of CO2 and H2O were derived from Li-7500 observations. The observational period, from early March to early August, includes both wet and dry season. OPC fluxes generally show net aerosol deposition both during wet and dry season with the largest downward fluxes during midday. CPC fluxes show different patterns in wet and dry season. During dry season, when number concentrations are higher, downward fluxes clearly dominate. In the wet season however, when number concentrations are lower, our data indicates that upward and downward fluxes are quite evenly distributed during course of a day. On average there is a peak in upward flux during late morning and another peak during the afternoon. Since the OPC fluxes in the same time show net deposition, there is an indication of net source of primary aerosol particles with diameters between 10 and 250 nm emitted from the rain forest. Future data analysis will hopefully shed light on origin and formation mechanism of these particles and thus provide a deeper insight in the rain forest - atmosphere interactions. The aerosol flux measurements were carried out as a part of the AMAZE project in collaboration with University of Sao Paulo, Brazil, and financial support was provided by Swedish International Development Cooperation

  7. Absolute Density Calibration Cell for Laser Induced Fluorescence Erosion Rate Measurements

    NASA Technical Reports Server (NTRS)

    Domonkos, Matthew T.; Stevens, Richard E.

    2001-01-01

    Flight qualification of ion thrusters typically requires testing on the order of 10,000 hours. Extensive knowledge of wear mechanisms and rates is necessary to establish design confidence prior to long duration tests. Consequently, real-time erosion rate measurements offer the potential both to reduce development costs and to enhance knowledge of the dependency of component wear on operating conditions. Several previous studies have used laser-induced fluorescence (LIF) to measure real-time, in situ erosion rates of ion thruster accelerator grids. Those studies provided only relative measurements of the erosion rate. In the present investigation, a molybdenum tube was resistively heated such that the evaporation rate yielded densities within the tube on the order of those expected from accelerator grid erosion. This work examines the suitability of the density cell as an absolute calibration source for LIF measurements, and the intrinsic error was evaluated.

  8. The influence of idealized surface heterogeneity on virtual turbulent flux measurements

    NASA Astrophysics Data System (ADS)

    De Roo, Frederik; Mauder, Matthias

    2018-04-01

    The imbalance of the surface energy budget in eddy-covariance measurements is still an unsolved problem. A possible cause is the presence of land surface heterogeneity, which affects the boundary-layer turbulence. To investigate the impact of surface variables on the partitioning of the energy budget of flux measurements in the surface layer under convective conditions, we set up a systematic parameter study by means of large-eddy simulation. For the study we use a virtual control volume approach, which allows the determination of advection by the mean flow, flux-divergence and storage terms of the energy budget at the virtual measurement site, in addition to the standard turbulent flux. We focus on the heterogeneity of the surface fluxes and keep the topography flat. The surface fluxes vary locally in intensity and these patches have different length scales. Intensity and length scales can vary for the two horizontal dimensions but follow an idealized chessboard pattern. Our main focus lies on surface heterogeneity of the kilometer scale, and one order of magnitude smaller. For these two length scales, we investigate the average response of the fluxes at a number of virtual towers, when varying the heterogeneity length within the length scale and when varying the contrast between the different patches. For each simulation, virtual measurement towers were positioned at functionally different positions (e.g., downdraft region, updraft region, at border between domains, etc.). As the storage term is always small, the non-closure is given by the sum of the advection by the mean flow and the flux-divergence. Remarkably, the missing flux can be described by either the advection by the mean flow or the flux-divergence separately, because the latter two have a high correlation with each other. For kilometer scale heterogeneity, we notice a clear dependence of the updrafts and downdrafts on the surface heterogeneity and likewise we also see a dependence of the energy

  9. Corrections of Heat Flux Measurements on Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Reinarts, Thomas R.; Matson, Monique L.; Walls, Laurie K.

    2002-01-01

    Knowledge of aerothermally induced convective heat transfer is important in the design of thermal protection systems for launch vehicles. Aerothermal models are typically calibrated via the data from circular, in-flight, flush-mounted surface heat flux gauges exposed to the thermal and velocity boundary layers of the external flow. Typically, copper or aluminum Schmidt- Boelter gauges, which take advantage of the one-dimensional Fourier's law of heat conduction, are used to measure the incident heat flux. This instrumentation, when surrounded by low-conductivity insulation, has a wall temperature significantly lower than the insulation. As a result of this substantial disturbance to the thermal boundary layer, the heat flux incident on the gauge tends to be considerably higher than it would have been on the insulation had the calorimeter not been there. In addition, radial conductive heat transfer from the hotter insulation can cause the calorimeter to indicate heat fluxes higher than actual. An overview of an effort to develop and calibrate gauge correction techniques for both of these effects will be presented.

  10. Measurement of the Cosmic Ray and Neutrino-Induced Muon Flux at the Sudbury Neutrino Observatory

    DOE R&D Accomplishments Database

    SNO collaboration; Aharmim, B.; Ahmed, S. N.; Andersen, T. C.; Anthony, A. E.; Barros, N.; Beier, E. W.; Bellerive, A.; Beltran, B.; Bergevin, M.; Biller, S. D.; Boudjemline, K.; Boulay, M. G.; Burritt, T. H.; Cai, B.; Chan, Y. D.; Chen, M.; Chon, M. C.; Cleveland, B. T.; Cox-Mobrand, G. A.; Currat, C. A.; Dai, X.; Dalnoki-Veress, F.; Deng, H.; Detwiler, J.; Doe, P. J.; Dosanjh, R. S.; Doucas, G.; Drouin, P.-L.; Duncan, F. A.; Dunford, M.; Elliott, S. R.; Evans, H. C.; Ewan, G. T.; Farine, J.; Fergani, H.; Fleurot, F.; Ford, R. J.; Formaggio, J. A.; Gagnon, N.; Goon, J. TM.; Grant, D. R.; Guillian, E.; Habib, S.; Hahn, R. L.; Hallin, A. L.; Hallman, E. D.; Hargrove, C. K.; Harvey, P. J.; Harvey, P. J.; Heeger, K. M.; Heintzelman, W. J.; Heise, J.; Helmer, R. L.; Hemingway, R. J.; Henning, R.; Hime, A.; Howard, C.; Howe, M. A.; Huang, M.; Jamieson, B.; Jelley, N. A.; Klein, J. R.; Kos, M.; Kruger, A.; Kraus, C.; Krauss, C. B.; Kutter, T.; Kyba, C. C. M.; Lange, R.; Law, J.; Lawson, I. T.; Lesko, K. T.; Leslie, J. R.; Levine, I.; Loach, J. C.; Luoma, S.; MacLellan, R.; Majerus, S.; Mak, H. B.; Maneira, J.; Marino, A. D.; Martin, R.; McCauley, N.; McDonald, A. B.; McGee, S.; Mifflin, C.; Miller, M. L.; Monreal, B.; Monroe, J.; Noble, A. J.; Oblath, N. S.; Okada, C. E.; O'Keeffe, H. M.; Opachich, Y.; Orebi Gann, G. D.; Oser, S. M.; Ott, R. A.; Peeters, S. J. M.; Poon, A. W. P.; Prior, G.; Rielage, K.; Robertson, B. C.; Robertson, R. G. H.; Rollin, E.; Schwendener, M. H.; Secrest, J. A.; Seibert, S. R.; Simard, O.; Simpson, J. J.; Sinclair, D.; Skensved, P.; Smith, M. W. E.; Sonley, T. J.; Steiger, T. D.; Stonehill, L. C.; Tagg, N.; Tesic, G.; Tolich, N.; Tsui, T.; Van de Water, R. G.; VanDevender, B. A.; Virtue, C. J.; Waller, D.; Waltham, C. E.; Wan Chan Tseung, H.; Wark, D. L.; Watson, P.; Wendland, J.; West, N.; Wilkerson, J. F.; Wilson, J. R.; Wouters, J. M.; Wright, A.; Yeh, M.; Zhang, F.; Zuber, K.

    2009-07-10

    Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and un-oscillated portion of the neutrino flux. A total of 514 muon-like events are measured between -1 {le} cos {theta}{sub zenith} 0.4 in a total exposure of 2.30 x 10{sup 14} cm{sup 2} s. The measured flux normalization is 1.22 {+-} 0.09 times the Bartol three-dimensional flux prediction. This is the first measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO with zenith angle cos {theta}{sub zenith} > 0.4 is measured to be (3.31 {+-} 0.01 (stat.) {+-} 0.09 (sys.)) x 10{sup -10} {micro}/s/cm{sup 2}.

  11. Eddy covariance carbonyl sulfide flux measurements with a quantum cascade laser absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Gerdel, Katharina; Spielmann, Felix M.; Hammerle, Albin; Wohlfahrt, Georg

    2016-04-01

    Carbonyl sulfide (COS) is the most abundant sulfur containing trace gas present in the troposphere at concentrations of around 500 ppt. Recent interest in COS by the ecosystem-physiological community has been sparked by the fact that COS co-diffuses into plant leaves pretty much the same way as carbon dioxide (CO2) does, but in contrast to CO2, COS is not known to be emitted by plants. Thus uptake of COS by vegetation has the potential to be used as a tracer for canopy gross photosynthesis, which cannot be measured directly, however represents a key term in the global carbon cycle. Since a few years, quantum cascade laser absorption spectrometers (QCLAS) are commercially available with the precision, sensitivity and time response suitable for eddy covariance (EC) flux measurements. While there exist a handful of published reports on EC flux measurements in the recent literature, no rigorous investigation of the applicability of QCLAS for EC COS flux measurements has been carried out so far, nor have been EC processing and QA/QC steps developed for carbon dioxide and water vapor flux measurements within FLUXNET been assessed for COS. The aim of this study is to close this knowledge gap, to discuss critical steps in the post-processing chain of COS EC flux measurements and to devise best-practice guidelines for COS EC flux data processing. To this end we collected EC COS (and CO2, H2O and CO) flux measurements above a temperate mountain grassland in Austria over the vegetation period 2015 with a commercially available QCLAS. We discuss various aspects of EC data post-processing, in particular issues with the time-lag estimation between sonic anemometer and QCLAS signals and QCLAS time series detrending, as well as QA/QC, in particular flux detection limits, random flux uncertainty, the interaction of various processing steps with common EC QA/QC filters (e.g. detrending and stationarity tests), u*-filtering, etc.

  12. Measuring Fast Calcium Fluxes in Cardiomyocytes

    PubMed Central

    Golebiewska, Urszula; Scarlata, Suzanne

    2011-01-01

    Cardiomyocytes have multiple Ca2+ fluxes of varying duration that work together to optimize function 1,2. Changes in Ca2+ activity in response to extracellular agents is predominantly regulated by the phospholipase Cβ- Gαq pathway localized on the plasma membrane which is stimulated by agents such as acetylcholine 3,4. We have recently found that plasma membrane protein domains called caveolae5,6 can entrap activated Gαq7. This entrapment has the effect of stabilizing the activated state of Gαq and resulting in prolonged Ca2+ signals in cardiomyocytes and other cell types8. We uncovered this surprising result by measuring dynamic calcium responses on a fast scale in living cardiomyocytes. Briefly, cells are loaded with a fluorescent Ca2+ indicator. In our studies, we used Ca2+ Green (Invitrogen, Inc.) which exhibits an increase in fluorescence emission intensity upon binding of calcium ions. The fluorescence intensity is then recorded for using a line-scan mode of a laser scanning confocal microscope. This method allows rapid acquisition of the time course of fluorescence intensity in pixels along a selected line, producing several hundreds of time traces on the microsecond time scale. These very fast traces are transferred into excel and then into Sigmaplot for analysis, and are compared to traces obtained for electronic noise, free dye, and other controls. To dissect Ca2+ responses of different flux rates, we performed a histogram analysis that binned pixel intensities with time. Binning allows us to group over 500 traces of scans and visualize the compiled results spatially and temporally on a single plot. Thus, the slow Ca2+ waves that are difficult to discern when the scans are overlaid due to different peak placement and noise, can be readily seen in the binned histograms. Very fast fluxes in the time scale of the measurement show a narrow distribution of intensities in the very short time bins whereas longer Ca2+ waves show binned data with a broad

  13. Measuring fast calcium fluxes in cardiomyocytes.

    PubMed

    Golebiewska, Urszula; Scarlata, Suzanne

    2011-11-29

    Cardiomyocytes have multiple Ca(2+) fluxes of varying duration that work together to optimize function (1,2). Changes in Ca(2+) activity in response to extracellular agents is predominantly regulated by the phospholipase Cβ- Gα(q;) pathway localized on the plasma membrane which is stimulated by agents such as acetylcholine (3,4). We have recently found that plasma membrane protein domains called caveolae(5,6) can entrap activated Gα(q;)(7). This entrapment has the effect of stabilizing the activated state of Gα(q;) and resulting in prolonged Ca(2+) signals in cardiomyocytes and other cell types(8). We uncovered this surprising result by measuring dynamic calcium responses on a fast scale in living cardiomyocytes. Briefly, cells are loaded with a fluorescent Ca(2+) indicator. In our studies, we used Ca(2+) Green (Invitrogen, Inc.) which exhibits an increase in fluorescence emission intensity upon binding of calcium ions. The fluorescence intensity is then recorded for using a line-scan mode of a laser scanning confocal microscope. This method allows rapid acquisition of the time course of fluorescence intensity in pixels along a selected line, producing several hundreds of time traces on the microsecond time scale. These very fast traces are transferred into excel and then into Sigmaplot for analysis, and are compared to traces obtained for electronic noise, free dye, and other controls. To dissect Ca(2+) responses of different flux rates, we performed a histogram analysis that binned pixel intensities with time. Binning allows us to group over 500 traces of scans and visualize the compiled results spatially and temporally on a single plot. Thus, the slow Ca(2+) waves that are difficult to discern when the scans are overlaid due to different peak placement and noise, can be readily seen in the binned histograms. Very fast fluxes in the time scale of the measurement show a narrow distribution of intensities in the very short time bins whereas longer Ca(2+) waves

  14. Verification of flux measurements made with in situ benthic chambers

    NASA Astrophysics Data System (ADS)

    Devol, Allan H.

    1987-06-01

    Exchange of solutes between the sediments and overlying water was measured in situ at two locations where the overlying waters were devoid of dissolved oxygen (Skan Bay, Alaska and the Tres Marias depression on the Mexican continental shelf). Measurements were made with a tripod capable of collecting eight sequential samples for analysis of dissolved gases and ions. The tripod also permitted tracer injection and the retrieval of sediments underlying the flux chambers. Because of the absence of oxygen, sediments from these areas did not contain benthic faunal populations, and it was possible to compare the benthic fluxes measured with the tripod with those calculated from pore water profiles. For solutes for which exchange was not limited by resistance in the diffuse sublayer (alkalinity, Si(OH) 4+, NH 4+, and PO 43-), tje 11 tirpod-measured fluxes agreed with those calculated from pore water gradients to within 25%. Benthic boundary layer thickness within the chambers as calculated from the initial rate of radiotracer uptake (tritiated water) varied from 405 to 605 μm in stirred chambers. Measured rates of NO 3- uptake were concordant with a boundary layer thickness of 600 μm.

  15. The impact of water temperature on the measurement of absolute dose

    NASA Astrophysics Data System (ADS)

    Islam, Naveed Mehdi

    To standardize reference dosimetry in radiation therapy, Task Group 51 (TG 51) of American Association of Physicist's in Medicine (AAPM) recommends that dose calibration measurements be made in a water tank at a depth of 10 cm and at a reference geometry. Methodologies are provided for calculating various correction factors to be applied in calculating the absolute dose. However the protocol does not specify the water temperature to be used. In practice, the temperature of water during dosimetry may vary considerably between independent sessions and different centers. In this work the effect of water temperature on absolute dosimetry has been investigated. Density of water varies with temperature, which in turn may impact the beam attenuation and scatter properties. Furthermore, due to thermal expansion or contraction air volume inside the chamber may change. All of these effects can result in a change in the measurement. Dosimetric measurements were made using a Farmer type ion chamber on a Varian Linear Accelerator for 6 MV and 23 MV photon energies for temperatures ranging from 10 to 40 °C. A thermal insulation was designed for the water tank in order to maintain relatively stable temperature over the duration of the experiment. Dose measured at higher temperatures were found to be consistently higher by a very small magnitude. Although the differences in dose were less than the uncertainty in each measurement, a linear regression of the data suggests that the trend is statistically significant with p-values of 0.002 and 0.013 for 6 and 23 MV beams respectively. For a 10 degree difference in water phantom temperatures, which is a realistic deviation across clinics, the final calculated reference dose can differ by 0.24% or more. To address this effect, first a reference temperature (e.g.22 °C) can be set as the standard; subsequently a correction factor can be implemented for deviations from this reference. Such a correction factor is expected to be of similar

  16. LOW-POWER SOLUTION FOR EDDY COVARIANCE MEASUREMENTS OF METHANE FLUX

    NASA Astrophysics Data System (ADS)

    Anderson, T.; Burba, G. G.; Komissarov, A.; McDermitt, D. K.; Xu, L.; Zona, D.; Oechel, W. C.; Schedlbauer, J. L.; Oberbauer, S. F.; Riensche, B.; Allyn, D.

    2009-12-01

    Open-path analyzers offer a number of advantages for measuring methane fluxes, including undisturbed in-situ flux measurements, spatial integration using the Eddy Covariance approach, zero frequency response errors due to tube attenuation, confident water and thermal density terms from co-located fast measurements of water and sonic temperature, and possibility of remote and mobile solar-powered or small-generator-powered deployments due to lower power demands in the absence of a pump. The LI-7700 open-path methane analyzer is a VCSEL (vertical-cavity surface-emitting laser)-based instrument. It employs an open Herriott cell and measures levels of methane with RMS noise below 5 ppb at 10 Hz sampling in controlled laboratory conditions. The power consumption of the stand-alone LI-7700 in steady-state is about 8W, so it can be deployed in any methane-generating location of interest on a portable or mobile solar-powered tower, and it does not have to have grid power or permanent industrial generator. Eddy Covariance measurements of methane flux using the LI-7700 open-path methane analyzer were conducted in 2006-2009 in five ecosystems with contrasting weather and moisture conditions: (1) sawgrass wetland in the Florida Everglades; (2) coastal wetlands in an Arctic tundra; and (3) pacific mangroves in Mexico; (4) maize field and (5) ryegrass field in Nebraska. Methane co-spectra behaved in a manner similar to that of the co-spectra of carbon dioxide, water vapor, and air temperature, demonstrating that the LI-7700 adequately measured fluctuations in methane concentration across the whole spectrum of frequencies contributing to vertical atmospheric turbulent transport at the experimental sites. All co-spectra also closely followed the Kaimal model, and demonstrated good agreement with another methane co-spectrum obtained with a TDLS (Tunable Diode Laser Spectroscope; Unisearch Associates, Inc.) over a peatland. Overall, hourly methane fluxes ranged from near-zero at

  17. 3-D density imaging with muon flux measurements from underground galleries

    NASA Astrophysics Data System (ADS)

    Lesparre, N.; Cabrera, J.; Marteau, J.

    2017-03-01

    Atmospheric muon flux measurements provide information on subsurface density distribution. In this study, muon flux was measured underground, in the Tournemire experimental platform (France). The objective was to image the medium between the galleries and the surface and evaluate the feasibility to detect the presence of discontinuities, for example, produced by secondary subvertical faults or by karstic networks. Measurements were performed from three different sites with a partial overlap of muon trajectories, offering the possibility to seek density variations at different depths. The conversion of the measured muon flux to average density values showed global variations further analysed through a 3-D nonlinear inversion procedure. Main results are the presence of a very low density region at the level of the upper aquifer, compatible with the presence of a karstic network hosting local cavities, and the absence of secondary faults. We discuss the validity of the present results and propose different strategies to improve the accuracy of such measurements and analysis.

  18. Precision determination of absolute neutron flux

    DOE PAGES

    Yue, A. T.; Anderson, E. S.; Dewey, M. S.; ...

    2018-06-08

    A technique for establishing the total neutron rate of a highly-collimated monochromatic cold neutron beam was demonstrated using an alpha–gamma counter. The method involves only the counting of measured rates and is independent of neutron cross sections, decay chain branching ratios, and neutron beam energy. For the measurement, a target of 10B-enriched boron carbide totally absorbed the neutrons in a monochromatic beam, and the rate of absorbed neutrons was determined by counting 478 keV gamma rays from neutron capture on 10B with calibrated high-purity germanium detectors. A second measurement based on Bragg diffraction from a perfect silicon crystal was performedmore » to determine the mean de Broglie wavelength of the beam to a precision of 0.024%. With these measurements, the detection efficiency of a neutron monitor based on neutron absorption on 6Li was determined to an overall uncertainty of 0.058%. We discuss the principle of the alpha–gamma method and present details of how the measurement was performed including the systematic effects. We further describe how this method may be used for applications in neutron dosimetry and metrology, fundamental neutron physics, and neutron cross section measurements.« less

  19. Precision determination of absolute neutron flux

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yue, A. T.; Anderson, E. S.; Dewey, M. S.

    A technique for establishing the total neutron rate of a highly-collimated monochromatic cold neutron beam was demonstrated using an alpha–gamma counter. The method involves only the counting of measured rates and is independent of neutron cross sections, decay chain branching ratios, and neutron beam energy. For the measurement, a target of 10B-enriched boron carbide totally absorbed the neutrons in a monochromatic beam, and the rate of absorbed neutrons was determined by counting 478 keV gamma rays from neutron capture on 10B with calibrated high-purity germanium detectors. A second measurement based on Bragg diffraction from a perfect silicon crystal was performedmore » to determine the mean de Broglie wavelength of the beam to a precision of 0.024%. With these measurements, the detection efficiency of a neutron monitor based on neutron absorption on 6Li was determined to an overall uncertainty of 0.058%. We discuss the principle of the alpha–gamma method and present details of how the measurement was performed including the systematic effects. We further describe how this method may be used for applications in neutron dosimetry and metrology, fundamental neutron physics, and neutron cross section measurements.« less

  20. Annual sediment flux estimates in a tidal strait using surrogate measurements

    USGS Publications Warehouse

    Ganju, N.K.; Schoellhamer, D.H.

    2006-01-01

    Annual suspended-sediment flux estimates through Carquinez Strait (the seaward boundary of Suisun Bay, California) are provided based on surrogate measurements for advective, dispersive, and Stokes drift flux. The surrogates are landward watershed discharge, suspended-sediment concentration at one location in the Strait, and the longitudinal salinity gradient. The first two surrogates substitute for tidally averaged discharge and velocity-weighted suspended-sediment concentration in the Strait, thereby providing advective flux estimates, while Stokes drift is estimated with suspended-sediment concentration alone. Dispersive flux is estimated using the product of longitudinal salinity gradient and the root-mean-square value of velocity-weighted suspended-sediment concentration as an added surrogate variable. Cross-sectional measurements validated the use of surrogates during the monitoring period. During high freshwater flow advective and dispersive flux were in the seaward direction, while landward dispersive flux dominated and advective flux approached zero during low freshwater flow. Stokes drift flux was consistently in the landward direction. Wetter than average years led to net export from Suisun Bay, while dry years led to net sediment import. Relatively low watershed sediment fluxes to Suisun Bay contribute to net export during the wet season, while gravitational circulation in Carquinez Strait and higher suspended-sediment concentrations in San Pablo Bay (seaward end of Carquinez Strait) are responsible for the net import of sediment during the dry season. Annual predictions of suspended-sediment fluxes, using these methods, will allow for a sediment budget for Suisun Bay, which has implications for marsh restoration and nutrient/contaminant transport. These methods also provide a general framework for estimating sediment fluxes in estuarine environments, where temporal and spatial variability of transport are large. ?? 2006 Elsevier Ltd. All rights

  1. Determining the Magnitude of Neutron and Galactic Cosmic Ray (GCR) Fluxes at the Moon using the Lunar Exploration Neutron Detector during the Historic Space-Age Era of High GCR Flux

    NASA Astrophysics Data System (ADS)

    Chin, G.; Sagdeev, R.; Boynton, W. V.; Mitrofanov, I. G.; Milikh, G. M.; Su, J. J.; Livengood, T. A.; McClanahan, T. P.; Evans, L.; Starr, R. D.; litvak, M. L.; Sanin, A.

    2013-12-01

    The Lunar Reconnaissance Orbiter (LRO) was launched June 18, 2009 during an historic space-age era of minimum solar activity [1]. The lack of solar sunspot activity signaled a complex set of heliospheric phenomena [2,3,4] that also gave rise to a period of unprecedentedly high Galactic Cosmic Ray (GCR) flux [5]. These events coincided with the primary mission of the Lunar Exploration Neutron Detector (LEND, [6]), onboard LRO in a nominal 50-km circular orbit of the Moon [7]. Methods to calculate the emergent neutron albedo population using Monte Carlo techniques [8] rely on an estimate of the GCR flux and spectra calibrated at differing periods of solar activity [9,10,11]. Estimating the actual GCR flux at the Moon during the LEND's initial period of operation requires a correction using a model-dependent heliospheric transport modulation parameter [12] to adjust the GCR flux appropriate to this unique solar cycle. These corrections have inherent uncertainties depending on model details [13]. Precisely determining the absolute neutron and GCR fluxes is especially important in understanding the emergent lunar neutrons measured by LEND and subsequently in estimating the hydrogen/water content in the lunar regolith [6]. LEND is constructed with a set of neutron detectors to meet differing purposes [6]. Specifically there are two sets of detector systems that measure the flux of epithermal neutrons: a) the uncollimated Sensor for Epi-Thermal Neutrons (SETN) and b) the Collimated Sensor for Epi-Thermal Neutrons (CSETN). LEND SETN and CSETN observations form a complementary set of simultaneous measurements that determine the absolute scale of emergent lunar neutron flux in an unambiguous fashion and without the need for correcting to differing solar-cycle conditions. LEND measurements are combined with a detailed understanding of the sources of instrumental back-ground, and the performance of CSETN and SETN. This comparison allows us to calculate a constant scale factor

  2. New ground-based lidar enables volcanic CO2 flux measurements.

    PubMed

    Aiuppa, Alessandro; Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Nuvoli, Marcello; Chiodini, Giovanni; Minopoli, Carmine; Tamburello, Giancarlo

    2015-09-01

    There have been substantial advances in the ability to monitor the activity of hazardous volcanoes in recent decades. However, obtaining early warning of eruptions remains challenging, because the patterns and consequences of volcanic unrests are both complex and nonlinear. Measuring volcanic gases has long been a key aspect of volcano monitoring since these mobile fluids should reach the surface long before the magma. There has been considerable progress in methods for remote and in-situ gas sensing, but measuring the flux of volcanic CO2-the most reliable gas precursor to an eruption-has remained a challenge. Here we report on the first direct quantitative measurements of the volcanic CO2 flux using a newly designed differential absorption lidar (DIAL), which were performed at the restless Campi Flegrei volcano. We show that DIAL makes it possible to remotely obtain volcanic CO2 flux time series with a high temporal resolution (tens of minutes) and accuracy (<30%). The ability of this lidar to remotely sense volcanic CO2 represents a major step forward in volcano monitoring, and will contribute improved volcanic CO2 flux inventories. Our results also demonstrate the unusually strong degassing behavior of Campi Flegrei fumaroles in the current ongoing state of unrest.

  3. Measurements of absolute absorption cross sections of ozone in the 185- to 254-nm wavelength region and the temperature dependence

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Esmond, J. R.; Freeman, D. E.; Parkinson, W. H.

    1993-01-01

    Laboratory measurements of the relative absorption cross sections of ozone at temperatures 195, 228, and 295 K have been made throughout the 185 to 254 nm wavelength region. The absolute absorption cross sections at the same temperatures have been measured at several discrete wavelengths in the 185 to 250 nm region. The absolute cross sections of ozone have been used to put the relative cross sections on a firm absolute basis throughout the 185 to 255 nm region. These recalibrated cross sections are slightly lower than those of Molina and Molina (1986), but the differences are within a few percent and would not be significant in atmospheric applications.

  4. Novel Sensor for the In Situ Measurement of Uranium Fluxes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hatfield, Kirk

    2015-02-10

    The goal of this project was to develop a sensor that incorporates the field-tested concepts of the passive flux meter to provide direct in situ measures of flux for uranium and groundwater in porous media. Measurable contaminant fluxes [J] are essentially the product of concentration [C] and groundwater flux or specific discharge [q ]. The sensor measures [J] and [q] by changes in contaminant and tracer amounts respectively on a sorbent. By using measurement rather than inference from static parameters, the sensor can directly advance conceptual and computational models for field scale simulations. The sensor was deployed in conjunction withmore » DOE in obtaining field-scale quantification of subsurface processes affecting uranium transport (e.g., advection) and transformation (e.g., uranium attenuation) at the Rifle IFRC Site in Rifle, Colorado. Project results have expanded our current understanding of how field-scale spatial variations in fluxes of uranium, groundwater and salient electron donor/acceptors are coupled to spatial variations in measured microbial biomass/community composition, effective field-scale uranium mass balances, attenuation, and stability. The coupling between uranium, various nutrients and micro flora can be used to estimate field-scale rates of uranium attenuation and field-scale transitions in microbial communities. This research focuses on uranium (VI), but the sensor principles and design are applicable to field-scale fate and transport of other radionuclides. Laboratory studies focused on sorbent selection and calibration, along with sensor development and validation under controlled conditions. Field studies were conducted at the Rifle IFRC Site in Rifle, Colorado. These studies were closely coordinated with existing SBR (formerly ERSP) projects to complement data collection. Small field tests were conducted during the first two years that focused on evaluating field-scale deployment procedures and validating sensor performance

  5. Field intercomparison of four methane gas analyzers suitable for eddy covariance flux measurements

    NASA Astrophysics Data System (ADS)

    Peltola, O.; Mammarella, I.; Haapanala, S.; Burba, G.; Vesala, T.

    2013-06-01

    Performances of four methane gas analyzers suitable for eddy covariance measurements are assessed. The assessment and comparison was performed by analyzing eddy covariance data obtained during summer 2010 (1 April to 26 October) at a pristine fen, Siikaneva, Southern Finland. High methane fluxes with pronounced seasonality have been measured at this fen. The four participating methane gas analyzers are commercially available closed-path units TGA-100A (Campbell Scientific Inc., USA), RMT-200 (Los Gatos Research, USA), G1301-f (Picarro Inc., USA) and an early prototype open-path unit Prototype-7700 (LI-COR Biosciences, USA). The RMT-200 functioned most reliably throughout the measurement campaign, during low and high flux periods. Methane fluxes from RMT-200 and G1301-f had the smallest random errors and the fluxes agree remarkably well throughout the measurement campaign. Cospectra and power spectra calculated from RMT-200 and G1301-f data agree well with corresponding temperature spectra during a high flux period. None of the gas analyzers showed statistically significant diurnal variation for methane flux. Prototype-7700 functioned only for a short period of time, over one month, in the beginning of the measurement campaign during low flux period, and thus, its overall accuracy and season-long performance were not assessed. The open-path gas analyzer is a practical choice for measurement sites in remote locations due to its low power demand, whereas for G1301-f methane measurements interference from water vapor is straightforward to correct since the instrument measures both gases simultaneously. In any case, if only the performance in this intercomparison is considered, RMT-200 performed the best and is the recommended choice if a new fast response methane gas analyzer is needed.

  6. Simulation and analysis of spectroscopic filter of rotational Raman lidar for absolute measurement of atmospheric temperature

    NASA Astrophysics Data System (ADS)

    Li, Qimeng; Li, Shichun; Hu, Xianglong; Zhao, Jing; Xin, Wenhui; Song, Yuehui; Hua, Dengxin

    2018-01-01

    The absolute measurement technique for atmospheric temperature can avoid the calibration process and improve the measurement accuracy. To achieve the rotational Raman temperature lidar of absolute measurement, the two-stage parallel multi-channel spectroscopic filter combined a first-order blazed grating with a fiber Bragg grating is designed and its performance is tested. The parameters and the optical path structure of the core cascaded-device (micron-level fiber array) are optimized, the optical path of the primary spectroscope is simulated and the maximum centrifugal distortion of the rotational Raman spectrum is approximately 0.0031 nm, the centrifugal ratio of 0.69%. The experimental results show that the channel coefficients of the primary spectroscope are 0.67, 0.91, 0.67, 0.75, 0.82, 0.63, 0.87, 0.97, 0.89, 0.87 and 1 by using the twelfth channel as a reference and the average FWHM is about 0.44 nm. The maximum deviation between the experimental wavelength and the theoretical value is approximately 0.0398 nm, with the deviation degree of 8.86%. The effective suppression to elastic scattering signal are 30.6, 35.2, 37.1, 38.4, 36.8, 38.2, 41.0, 44.3, 44.0, 46.7 dB. That means, combined with the second spectroscope, the suppression at least is up to 65 dB. Therefore we can fine extract single rotational Raman line to achieve the absolute measurement technique.

  7. Research on effects of baffle position in an integrating sphere on the luminous flux measurement

    NASA Astrophysics Data System (ADS)

    Lin, Fangsheng; Li, Tiecheng; Yin, Dejin; Lai, Lei; Xia, Ming

    2016-09-01

    In the field of optical metrology, luminous flux is an important index to characterize the quality of electric light source. Currently, the majority of luminous flux measurement is based on the integrating sphere method, so measurement accuracy of integrating sphere is the key factor. There are plenty of factors affecting the measurement accuracy, such as coating, power and the position of light source. However, the baffle which is a key part of integrating sphere has important effects on the measurement results. The paper analyzes in detail the principle of an ideal integrating sphere. We use moving rail to change the relative position of baffle and light source inside the sphere. By experiments, measured luminous flux values at different distances between the light source and baffle are obtained, which we used to take analysis of the effects of different baffle position on the measurement. By theoretical calculation, computer simulation and experiment, we obtain the optimum position of baffle for luminous flux measurements. Based on the whole luminous flux measurement error analysis, we develop the methods and apparatus to improve the luminous flux measurement accuracy and reliability. It makes our unifying and transferring work of the luminous flux more accurate in East China and provides effective protection for our traceability system.

  8. Comparison of measured and modeled radiation, heat and water vapor fluxes: FIFE pilot study

    NASA Technical Reports Server (NTRS)

    Blad, Blaine L.; Hubbard, Kenneth G.; Verma, Shashi B.; Starks, Patrick; Norman, John M.; Walter-Shea, Elizabeth

    1987-01-01

    The feasibility of using radio frequency receivers to collect data from automated weather stations to model fluxes of latent heat, sensible heat, and radiation using routine weather data collected by automated weather stations was tested and the estimated fluxes were compared with fluxes measured over wheat. The model Cupid was used to model the fluxes. Two or more automated weather stations, interrogated by radio frequency and other means, were utilized to examine some of the climatic variability of the First ISLSCP (International Satellite Land-Surface Climatology Project) Field Experiment (FIFE) site, to measure and model reflected and emitted radiation streams from various locations at the site and to compare modeled latent and sensible heat fluxes with measured values. Some bidirectional reflected and emitted radiation data were collected from 23 locations throughout the FIFE site. Analysis of these data along with analysis of the measured sensible and latent heat fluxes is just beginning.

  9. Measurements of Absolute Hadronic Branching Fractions of the Λ_{c}^{+} Baryon.

    PubMed

    Ablikim, M; Achasov, M N; Ai, X C; Albayrak, O; Albrecht, M; Ambrose, D J; Amoroso, A; An, F F; An, Q; Bai, J Z; Baldini Ferroli, R; Ban, Y; Bennett, D W; Bennett, J V; Bertani, M; Bettoni, D; Bian, J M; Bianchi, F; Boger, E; Boyko, I; Briere, R A; Cai, H; Cai, X; Cakir, O; Calcaterra, A; Cao, G F; Cetin, S A; Chang, J F; Chelkov, G; Chen, G; Chen, H S; Chen, H Y; Chen, J C; Chen, M L; Chen, S J; Chen, X; Chen, X R; Chen, Y B; Cheng, H P; Chu, X K; Cibinetto, G; Dai, H L; Dai, J P; Dbeyssi, A; Dedovich, D; Deng, Z Y; Denig, A; Denysenko, I; Destefanis, M; De Mori, F; Ding, Y; Dong, C; Dong, J; Dong, L Y; Dong, M Y; Dou, Z L; Du, S X; Duan, P F; Eren, E E; Fan, J Z; Fang, J; Fang, S S; Fang, X; Fang, Y; Farinelli, R; Fava, L; Fedorov, O; Feldbauer, F; Felici, G; Feng, C Q; Fioravanti, E; Fritsch, M; Fu, C D; Gao, Q; Gao, X L; Gao, X Y; Gao, Y; Gao, Z; Garzia, I; Goetzen, K; Gong, L; Gong, W X; Gradl, W; Greco, M; Gu, M H; Gu, Y T; Guan, Y H; Guo, A Q; Guo, L B; Guo, Y; Guo, Y P; Haddadi, Z; Hafner, A; Han, S; Hao, X Q; Harris, F A; He, K L; Held, T; Heng, Y K; Hou, Z L; Hu, C; Hu, H M; Hu, J F; Hu, T; Hu, Y; Huang, G S; Huang, J S; Huang, X T; Huang, Y; Hussain, T; Ji, Q; Ji, Q P; Ji, X B; Ji, X L; Jiang, L W; Jiang, X S; Jiang, X Y; Jiao, J B; Jiao, Z; Jin, D P; Jin, S; Johansson, T; Julin, A; Kalantar-Nayestanaki, N; Kang, X L; Kang, X S; Kavatsyuk, M; Ke, B C; Kiese, P; Kliemt, R; Kloss, B; Kolcu, O B; Kopf, B; Kornicer, M; Kuehn, W; Kupsc, A; Lange, J S; Lara, M; Larin, P; Leng, C; Li, C; Li, Cheng; Li, D M; Li, F; Li, F Y; Li, G; Li, H B; Li, J C; Li, Jin; Li, K; Li, K; Li, Lei; Li, P R; Li, Q Y; Li, T; Li, W D; Li, W G; Li, X L; Li, X M; Li, X N; Li, X Q; Li, Z B; Liang, H; Liang, Y F; Liang, Y T; Liao, G R; Lin, D X; Liu, B J; Liu, C X; Liu, D; Liu, F H; Liu, Fang; Liu, Feng; Liu, H B; Liu, H H; Liu, H H; Liu, H M; Liu, J; Liu, J B; Liu, J P; Liu, J Y; Liu, K; Liu, K Y; Liu, L D; Liu, P L; Liu, Q; Liu, S B; Liu, X; Liu, Y B; Liu, Z A; Liu, Zhiqing; Loehner, H; Lou, X C; Lu, H J; Lu, J G; Lu, Y; Lu, Y P; Luo, C L; Luo, M X; Luo, T; Luo, X L; Lyu, X R; Ma, F C; Ma, H L; Ma, L L; Ma, Q M; Ma, T; Ma, X N; Ma, X Y; Ma, Y M; Maas, F E; Maggiora, M; Mao, Y J; Mao, Z P; Marcello, S; Messchendorp, J G; Min, J; Mitchell, R E; Mo, X H; Mo, Y J; Morales Morales, C; Muchnoi, N Yu; Muramatsu, H; Nefedov, Y; Nerling, F; Nikolaev, I B; Ning, Z; Nisar, S; Niu, S L; Niu, X Y; Olsen, S L; Ouyang, Q; Pacetti, S; Pan, Y; Patteri, P; Pelizaeus, M; Peng, H P; Peters, K; Pettersson, J; Ping, J L; Ping, R G; Poling, R; Prasad, V; Qi, H R; Qi, M; Qian, S; Qiao, C F; Qin, L Q; Qin, N; Qin, X S; Qin, Z H; Qiu, J F; Rashid, K H; Redmer, C F; Ripka, M; Rong, G; Rosner, Ch; Ruan, X D; Santoro, V; Sarantsev, A; Savrié, M; Schoenning, K; Schumann, S; Shan, W; Shao, M; Shen, C P; Shen, P X; Shen, X Y; Sheng, H Y; Song, W M; Song, X Y; Sosio, S; Spataro, S; Sun, G X; Sun, J F; Sun, S S; Sun, Y J; Sun, Y Z; Sun, Z J; Sun, Z T; Tang, C J; Tang, X; Tapan, I; Thorndike, E H; Tiemens, M; Ullrich, M; Uman, I; Varner, G S; Wang, B; Wang, B L; Wang, D; Wang, D Y; Wang, K; Wang, L L; Wang, L S; Wang, M; Wang, P; Wang, P L; Wang, S G; Wang, W; Wang, W P; Wang, X F; Wang, Y D; Wang, Y F; Wang, Y Q; Wang, Z; Wang, Z G; Wang, Z H; Wang, Z Y; Weber, T; Wei, D H; Wei, J B; Weidenkaff, P; Wen, S P; Wiedner, U; Wolke, M; Wu, L H; Wu, Z; Xia, L; Xia, L G; Xia, Y; Xiao, D; Xiao, H; Xiao, Z J; Xie, Y G; Xiu, Q L; Xu, G F; Xu, L; Xu, Q J; Xu, Q N; Xu, X P; Yan, L; Yan, W B; Yan, W C; Yan, Y H; Yang, H J; Yang, H X; Yang, L; Yang, Y X; Ye, M; Ye, M H; Yin, J H; Yu, B X; Yu, C X; Yu, J S; Yuan, C Z; Yuan, W L; Yuan, Y; Yuncu, A; Zafar, A A; Zallo, A; Zeng, Y; Zeng, Z; Zhang, B X; Zhang, B Y; Zhang, C; Zhang, C C; Zhang, D H; Zhang, H H; Zhang, H Y; Zhang, J J; Zhang, J L; Zhang, J Q; Zhang, J W; Zhang, J Y; Zhang, J Z; Zhang, K; Zhang, L; Zhang, X Y; Zhang, Y; Zhang, Y H; Zhang, Y N; Zhang, Y T; Zhang, Yu; Zhang, Z H; Zhang, Z P; Zhang, Z Y; Zhao, G; Zhao, J W; Zhao, J Y; Zhao, J Z; Zhao, Lei; Zhao, Ling; Zhao, M G; Zhao, Q; Zhao, Q W; Zhao, S J; Zhao, T C; Zhao, Y B; Zhao, Z G; Zhemchugov, A; Zheng, B; Zheng, J P; Zheng, W J; Zheng, Y H; Zhong, B; Zhou, L; Zhou, X; Zhou, X K; Zhou, X R; Zhou, X Y; Zhu, K; Zhu, K J; Zhu, S; Zhu, S H; Zhu, X L; Zhu, Y C; Zhu, Y S; Zhu, Z A; Zhuang, J; Zotti, L; Zou, B S; Zou, J H

    2016-02-05

    We report the first measurement of absolute hadronic branching fractions of Λ_{c}^{+} baryon at the Λ_{c}^{+}Λ[over ¯]_{c}^{-} production threshold, in the 30 years since the Λ_{c}^{+} discovery. In total, 12 Cabibbo-favored Λ_{c}^{+} hadronic decay modes are analyzed with a double-tag technique, based on a sample of 567  pb^{-1} of e^{+}e^{-} collisions at sqrt[s]=4.599  GeV recorded with the BESIII detector. A global least-squares fitter is utilized to improve the measured precision. Among the measurements for twelve Λ_{c}^{+} decay modes, the branching fraction for Λ_{c}^{+}→pK^{-}π^{+} is determined to be (5.84±0.27±0.23)%, where the first uncertainty is statistical and the second is systematic. In addition, the measurements of the branching fractions of the other 11 Cabibbo-favored hadronic decay modes are significantly improved.

  10. The radiation budget of stratocumulus clouds measured by tethered balloon instrumentation: Variability of flux measurements

    NASA Technical Reports Server (NTRS)

    Duda, David P.; Stephens, Graeme L.; Cox, Stephen K.

    1990-01-01

    Measurements of longwave and shortwave radiation were made using an instrument package on the NASA tethered balloon during the FIRE Marine Stratocumulus experiment. Radiation data from two pairs of pyranometers were used to obtain vertical profiles of the near-infrared and total solar fluxes through the boundary layer, while a pair of pyrgeometers supplied measurements of the longwave fluxes in the cloud layer. The radiation observations were analyzed to determine heating rates and to measure the radiative energy budget inside the stratocumulus clouds during several tethered balloon flights. The radiation fields in the cloud layer were also simulated by a two-stream radiative transfer model, which used cloud optical properties derived from microphysical measurements and Mie scattering theory.

  11. Tropical Gravity Wave Momentum Fluxes and Latent Heating Distributions

    NASA Technical Reports Server (NTRS)

    Geller, Marvin A.; Zhou, Tiehan; Love, Peter T.

    2015-01-01

    Recent satellite determinations of global distributions of absolute gravity wave (GW) momentum fluxes in the lower stratosphere show maxima over the summer subtropical continents and little evidence of GW momentum fluxes associated with the intertropical convergence zone (ITCZ). This seems to be at odds with parameterizations forGWmomentum fluxes, where the source is a function of latent heating rates, which are largest in the region of the ITCZ in terms of monthly averages. The authors have examined global distributions of atmospheric latent heating, cloud-top-pressure altitudes, and lower-stratosphere absolute GW momentum fluxes and have found that monthly averages of the lower-stratosphere GW momentum fluxes more closely resemble the monthly mean cloud-top altitudes rather than the monthly mean rates of latent heating. These regions of highest cloud-top altitudes occur when rates of latent heating are largest on the time scale of cloud growth. This, plus previously published studies, suggests that convective sources for stratospheric GW momentum fluxes, being a function of the rate of latent heating, will require either a climate model to correctly model this rate of latent heating or some ad hoc adjustments to account for shortcomings in a climate model's land-sea differences in convective latent heating.

  12. A True Eddy Accumulation - Eddy Covariance hybrid for measurements of turbulent trace gas fluxes

    NASA Astrophysics Data System (ADS)

    Siebicke, Lukas

    2016-04-01

    Eddy covariance (EC) is state-of-the-art in directly and continuously measuring turbulent fluxes of carbon dioxide and water vapor. However, low signal-to-noise ratios, high flow rates and missing or complex gas analyzers limit it's application to few scalars. True eddy accumulation, based on conditional sampling ideas by Desjardins in 1972, requires no fast response analyzers and is therefore potentially applicable to a wider range of scalars. Recently we showed possibly the first successful implementation of True Eddy Accumulation (TEA) measuring net ecosystem exchange of carbon dioxide of a grassland. However, most accumulation systems share the complexity of having to store discrete air samples in physical containers representing entire flux averaging intervals. The current study investigates merging principles of eddy accumulation and eddy covariance, which we here refer to as "true eddy accumulation in transient mode" (TEA-TM). This direct flux method TEA-TM combines true eddy accumulation with continuous sampling. The TEA-TM setup is simpler than discrete accumulation methods while avoiding the need for fast response gas analyzers and high flow rates required for EC. We implemented the proposed TEA-TM method and measured fluxes of carbon dioxide (CO2), methane (CH4) and water vapor (H2O) above a mixed beech forest at the Hainich Fluxnet and ICOS site, Germany, using a G2301 laser spectrometer (Picarro Inc., USA). We further simulated a TEA-TM sampling system using measured high frequency CO2 time series from an open-path gas analyzer. We operated TEA-TM side-by-side with open-, enclosed- and closed-path EC flux systems for CO2, H2O and CH4 (LI-7500, LI-7200, LI-6262, LI-7700, Licor, USA, and FGGA LGR, USA). First results show that TEA-TM CO2 fluxes were similar to EC fluxes. Remaining differences were similar to those between the three eddy covariance setups (open-, enclosed- and closed-path gas analyzers). Measured TEA-TM CO2 fluxes from our physical

  13. Absolute Thermal SST Measurements over the Deepwater Horizon Oil Spill

    NASA Astrophysics Data System (ADS)

    Good, W. S.; Warden, R.; Kaptchen, P. F.; Finch, T.; Emery, W. J.

    2010-12-01

    Climate monitoring and natural disaster rapid assessment require baseline measurements that can be tracked over time to distinguish anthropogenic versus natural changes to the Earth system. Disasters like the Deepwater Horizon Oil Spill require constant monitoring to assess the potential environmental and economic impacts. Absolute calibration and validation of Earth-observing sensors is needed to allow for comparison of temporally separated data sets and provide accurate information to policy makers. The Ball Experimental Sea Surface Temperature (BESST) radiometer was designed and built by Ball Aerospace to provide a well calibrated measure of sea surface temperature (SST) from an unmanned aerial system (UAS). Currently, emissive skin SST observed by satellite infrared radiometers is validated by shipborne instruments that are expensive to deploy and can only take a few data samples along the ship track to overlap within a single satellite pixel. Implementation on a UAS will allow BESST to map the full footprint of a satellite pixel and perform averaging to remove any local variability due to the difference in footprint size of the instruments. It also enables the capability to study this sub-pixel variability to determine if smaller scale effects need to be accounted for in models to improve forecasting of ocean events. In addition to satellite sensor validation, BESST can distinguish meter scale variations in SST which could be used to remotely monitor and assess thermal pollution in rivers and coastal areas as well as study diurnal and seasonal changes to bodies of water that impact the ocean ecosystem. BESST was recently deployed on a conventional Twin Otter airplane for measurements over the Gulf of Mexico to access the thermal properties of the ocean surface being affected by the oil spill. Results of these measurements will be presented along with ancillary sensor data used to eliminate false signals including UV and Synthetic Aperture Radar (SAR

  14. Flux Measurements of Trace Gases, Aerosols and Energy from the Urban Core of Mexico City

    NASA Astrophysics Data System (ADS)

    Velasco, E.; Molina, L.; Lamb, B.; Pressley, S.; Grivicke, R.; Westberg, H.; Jobson, T.; Allwine, E.; Coons, T.; Jimenez, J.; Nemitz, E.; Alexander, L. M.; Worsnop, D.; Ramos, R.

    2007-05-01

    As part of the MILAGRO field campaign in March 2006 we deployed a flux system in a busy district of Mexico City surrounded by congested avenues. The flux system consisted of a tall tower instrumented with fast-response sensors coupled with eddy covariance (EC) techniques to measure fluxes of volatile organic compounds (VOCs), CO2, CO, aerosols and energy. The measured fluxes represent direct measurements of emissions that include all major and minor emission sources from a typical residential and commercial district. In a previous study we demonstrated that the EC techniques are valuable tools to evaluate emissions inventories in urban areas, and understand better the atmospheric chemistry and the role that megacities play in global change. We measured fluxes of olefins using a Fast Olefin Sensor (FOS) and the EC technique, fluxes of aromatic and oxygenated VOCs by Proton Transfer Reaction-Mass Spectroscopy (PTR-MS) and the disjunct eddy covariance (DEC) technique, fluxes of CO2 and H2O with an open path Infrared Gas Analyzer (IRGA) and the EC technique, fluxes of CO using a modified gradient method and a commercial CO instrument, and fluxes of aerosols (organics, nitrates and sulfates) using an Aerodyne Aerosol Mass Spectrometer (AMS) and the EC technique. In addition we used a disjunct eddy accumulation (DEA) system to extend the number of VOCs. This system collected whole air samples as function of the direction of the vertical wind component, and the samples were analyzed on site using gas chromatography / flame ionization detection (GC-FID). We also measured fluxes of sensible and latent heat by EC and the radiation components with a net radiometer. Overall, these flux measurements confirm the results of our previous flux measurements in Mexico City in terms of the magnitude, composition, and distribution. We found that the urban surface is a net source of CO2 and VOCs. The diurnal patterns show clear anthropogenic signatures, with important contributions from

  15. A method for obtaining distributed surface flux measurements in complex terrain

    NASA Astrophysics Data System (ADS)

    Daniels, M. H.; Pardyjak, E.; Nadeau, D. F.; Barrenetxea, G.; Brutsaert, W. H.; Parlange, M. B.

    2011-12-01

    Sonic anemometers and gas analyzers can be used to measure fluxes of momentum, heat, and moisture over flat terrain, and with the proper corrections, over sloping terrain as well. While this method of obtaining fluxes is currently the most accurate available, the instruments themselves are costly, making installation of many stations impossible for most campaign budgets. Small, commercial automatic weather stations (Sensorscope) are available at a fraction of the cost of sonic anemometers or gas analyzers. Sensorscope stations use slow-response instruments to measure standard meteorological variables, including wind speed and direction, air temperature, humidity, surface skin temperature, and incoming solar radiation. The method presented here makes use of one sonic anemometer and one gas analyzer along with a dozen Sensorscope stations installed throughout the Val Ferret catchment in southern Switzerland in the summers of 2009, 2010 and 2011. Daytime fluxes are calculated using Monin-Obukhov similarity theory in conjunction with the surface energy balance at each Sensorscope station as well as at the location of the sonic anemometer and gas analyzer, where a suite of additional slow-response instruments were co-located. Corrections related to slope angle were made for wind speeds and incoming shortwave radiation measured by the horizontally-mounted cup anemometers and incoming solar radiation sensors respectively. A temperature correction was also applied to account for daytime heating inside the radiation shield on the slow-response temperature/humidity sensors. With these corrections, we find a correlation coefficient of 0.77 between u* derived using Monin-Obukhov similarity theory and that of the sonic anemometer. Calculated versus measured heat fluxes also compare well and local patterns of latent heat flux and measured surface soil moisture are correlated.

  16. Comparative study of elemental mercury flux measurement techniques over a Fennoscandian boreal peatland

    NASA Astrophysics Data System (ADS)

    Osterwalder, S.; Sommar, J.; Åkerblom, S.; Jocher, G.; Fritsche, J.; Nilsson, M. B.; Bishop, K.; Alewell, C.

    2018-01-01

    Quantitative estimates of the land-atmosphere exchange of gaseous elemental mercury (GEM) are biased by the measurement technique employed, because no standard method or scale in space and time are agreed upon. Here we present concurrent GEM exchange measurements over a boreal peatland using a novel relaxed eddy accumulation (REA) system, a rectangular Teflon® dynamic flux chamber (DFC) and a DFC designed according to aerodynamic considerations (Aero-DFC). During four consecutive days the DFCs were placed alternately on two measurement plots in every cardinal direction around the REA sampling mast. Spatial heterogeneity in peat surface characteristics (0-34 cm) was identified by measuring total mercury in eight peat cores (57 ± 8 ng g-1, average ± SE), vascular plant coverage (32-52%), water table level (4.5-14.1 cm) and dissolved gaseous elemental mercury concentrations (28-51 pg L-1) in the peat water. The GEM fluxes measured by the DFCs showed a distinct diel pattern, but no spatial difference in the average fluxes was detected (ANOVA, α = 0.05). Even though the correlation between the Teflon® DFC and Aero-DFC was significant (r = 0.76, p < 0.05) the cumulative flux of the Aero-DFC was a factor of three larger. The average flux of the Aero-DFC (1.9 ng m-2 h-1) and REA (2 ng m-2 h-1) were in good agreement. The results indicate that the novel REA design is in agreement for cumulative flux estimates with the Aero-DFC, which incorporates the effect of atmospheric turbulence. The comparison was performed over a fetch with spatially rather homogenous GEM flux dynamics under fairly consistent weather conditions, minimizing the effect of weather influence on the data from the three measurement systems. However, in complex biomes with heterogeneous surface characteristics where there can be large spatial variability in GEM gas exchange, the small footprint of chambers (<0.2 m2) makes for large coefficients of variation. Thus many chamber measurement replications

  17. Magnitude and directional measures of water and Cr(VI) fluxes by passive flux meter.

    PubMed

    Campbell, Timothy J; Hatfield, Kirk; Klammler, Harald; Annable, Michael D; Rao, P S C

    2006-10-15

    A new configuration of the passive fluxmeter (PFM) is presented that provides for simultaneous measurements of both the magnitude and the direction of ambient groundwater specific discharge qo and Cr(VI) mass flux J(Cr). The PFM is configured as a cylindrical unit with an interior divided into a center section and three outer sectors, each packed with a granular anion exchange resin having high sorption capacity for the Cr(VI) oxyanions CrO4(2-) and HCrO4-. The sorbent in the center section is preloaded with benzoate as the "resident" tracer. Laboratory experiments were conducted in which PFMs were placed in porous packed bed columns, through which was passed a measured volume of synthetic groundwater containing Cr(VI). During the deployment period, some of the resident tracer is depleted while the Cr(VI) is sorbed. The resin was then removed from the four sectors separately and extracted to determine the "captured" mass of Cr(VI) and the residual mass of the resident tracer in each. Cumulative specific discharge, q0t, values were assessed using the residual mass of benzoate retained in the center section. The direction of this discharge theta was ascertained from the mass distribution of benzoate intercepted and retained in the outer three sections of the PFM. Cumulative chromium fluxes, J(Cr)t, were quantified using the total Cr(VI) mass intercepted and retained on the PFM. Experiments produced an average measurement error for direction theta of 3 degrees +/- 14 degrees, while the average measurement errors for q0 and J(Cr) were, respectively, -8% +/- 15% and -12% +/- 23%. Results demonstrate the potential utility of the new PFM configuration for characterizing groundwater and contaminant fluxes.

  18. Campaign-Style Measurements of Vertical Seafloor Deformation in the Cascadia Subduction Zone Using an Absolute Self-Calibrating Pressure Recorder

    NASA Astrophysics Data System (ADS)

    Cook, M. J.; Sasagawa, G. S.; Roland, E. C.; Schmidt, D. A.; Wilcock, W. S. D.; Zumberge, M. A.

    2017-12-01

    Seawater pressure can be used to measure vertical seafloor deformation since small seafloor height changes produce measurable pressure changes. However, resolving secular vertical deformation near subduction zones can be difficult due to pressure gauge drift. A typical gauge drift rate of about 10 cm/year exceeds the expected secular rate of 1 cm/year or less in Cascadia. The absolute self-calibrating pressure recorder (ASCPR) was developed to solve the issue of gauge drift by using a deadweight calibrator to make campaign-style measurements of the absolute seawater pressure. Pressure gauges alternate between observing the ambient seawater pressure and the deadweight calibrator pressure, which is an accurately known reference value, every 10-20 minutes for several hours. The difference between the known reference pressure and the observed seafloor pressure allows offsets and transients to be corrected to determine the true, absolute seafloor pressure. Absolute seafloor pressure measurements provide a great utility for geodetic deformation studies. The measurements provide instrument-independent, benchmark values that can be used far into the future as epoch points in long-term time series or as important calibration points for other continuous pressure records. The ASCPR was first deployed in Cascadia in 2014 and 2015, when seven concrete seafloor benchmarks were placed along a trench-perpendicular profile extending from 20 km to 105 km off the central Oregon coast. Two benchmarks have ASCPR measurements that span three years, one benchmark spans two years, and four benchmarks span one year. Measurement repeatability is currently 3 to 4 cm, but we anticipate accuracy on the order of 1 cm with improvements to the instrument metrology and processing tidal and non-tidal oceanographic signals.

  19. A direct passive method for measuring water and contaminant fluxes in porous media

    NASA Astrophysics Data System (ADS)

    Hatfield, Kirk; Annable, Michael; Cho, Jaehyun; Rao, P. S. C.; Klammler, Harald

    2004-12-01

    This paper introduces a new direct method for measuring water and contaminant fluxes in porous media. The method uses a passive flux meter (PFM), which is essentially a self-contained permeable unit properly sized to fit tightly in a screened well or boring. The meter is designed to accommodate a mixed medium of hydrophobic and/or hydrophilic permeable sorbents, which retain dissolved organic/inorganic contaminants present in the groundwater flowing passively through the meter. The contaminant mass intercepted and retained on the sorbent is used to quantify cumulative contaminant mass flux. The sorptive matrix is also impregnated with known amounts of one or more water soluble 'resident tracers'. These tracers are displaced from the sorbent at rates proportional to the groundwater flux; hence, in the current meter design, the resident tracers are used to quantify cumulative groundwater flux. Theory is presented and quantitative tools are developed to interpret the water flux from tracers possessing linear and nonlinear elution profiles. The same theory is extended to derive functional relationships useful for quantifying cumulative contaminant mass flux. To validate theory and demonstrate the passive flux meter, results of multiple box-aquifer experiments are presented and discussed. From these experiments, it is seen that accurate water flux measurements are obtained when the tracer used in calculations resides in the meter at levels representing 20 to 70 percent of the initial condition. 2,4-Dimethyl-3-pentanol (DMP) is used as a surrogate groundwater contaminant in the box aquifer experiments. Cumulative DMP fluxes are measured within 5% of known fluxes. The accuracy of these estimates generally increases with the total volume of water intercepted.

  20. Absolute Determination of High DC Voltages by Means of Frequency Measurement

    NASA Astrophysics Data System (ADS)

    Peier, Dirk; Schulz, Bernd

    1983-01-01

    A novel absolute measuring procedure is presented for the definition of fixed points of the voltage in the 100 kV range. The method is based on transit time measurements with accelerated electrons. By utilizing the selective interaction of a monoenergetic electron beam with the electromagnetic field of a special cavity resonator, the voltage is referred to fundamental constants and the base unit second. Possible balance voltages are indicated by a current detector. Experimental investigations are carried out with resonators in the normal conducting range. With a copper resonator operating at the temperature of boiling nitrogen (77 K), the relative uncertainty of the voltage points is estimated to be +/- 4 × 10-4. The technically realizable uncertainty can be reduced to +/- 1 × 10-5 by the proposed application of a superconducting niobium resonator. Thus this measuring device becomes suitable as a primary standard for the high-voltage range.

  1. An inter-comparison of surface energy flux measurement systems used during FIFE, 1987

    NASA Technical Reports Server (NTRS)

    Nie, D.; Kanemasu, E. T.; Fritschen, L. J.; Weaver, H.; Smith, E. A.; Verma, S. B.; Field, R. T.; Kustas, W.; Stewart, J. B.

    1990-01-01

    During the first International Satellite Land Surface Climatology Program Field Experiment (FIFE-87), surface energy fluxes were measured at 22 flux sites by nine groups of scientists using different measuring systems. A rover Bowen ratio station was taken to nearly all the flux stations to serve as a reference for estimating the instrument related differences. The rover system was installed within a few meters from the host instrument of a site. Net radiation, Bowen ratio, and latent heat fluxes were compared between the rover and the host for the stations visited. Linear regression analysis was used to examine the relationship between rover measurements and host measurements. These inter-comparisons are needed to examine the influence of instrumentation on measurement uncertainty. Highly significant effects of instrument type were detected from these comparisons. Instruments of the same type showed average differences of less than 5 percent for net radiation, 10 percent for Bowen ratio, and 6 percent for latent heat flux. The corresponding average differences for different types of instruments can be up to 10, 30, and 20 percent respectively. The Didcot net radiometer gave higher net radiation while the Swissteco type showed lower values, as compared to the corrected REBS model. The 4-way components methed and the Thornswaite type give similar values to the REBS. The SERBS type Bowen ratio systems exhibit slightly lower Bowen ratios and thus higher latent heat fluxes, compared to the AZET systems. Eddy correlation systems showed slightly lower latent heat flux in comparison to the Bowen ratio systems.

  2. Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat-spectral response.

    PubMed

    Troussel, Ph; Villette, B; Emprin, B; Oudot, G; Tassin, V; Bridou, F; Delmotte, F; Krumrey, M

    2014-01-01

    CEA implemented an absolutely calibrated broadband soft X-ray spectrometer called DMX on the Omega laser facility at the Laboratory for Laser Energetics (LLE) in 1999 to measure radiant power and spectral distribution of the radiation of the Au plasma. The DMX spectrometer is composed of 20 channels covering the spectral range from 50 eV to 20 keV. The channels for energies below 1.5 keV combine a mirror and a filter with a coaxial photo-emissive detector. For the channels above 5 keV the photoemissive detector is replaced by a conductive detector. The intermediate energy channels (1.5 keV < photon energy < 5 keV) use only a filter and a coaxial detector. A further improvement of DMX consists in flat-response X-ray channels for a precise absolute measurement of the photon flux in the photon energy range from 0.1 keV to 6 keV. Such channels are equipped with a filter, a Multilayer Mirror (MLM), and a coaxial detector. We present as an example the development of channel for the gold M emission lines in the photon energy range from 2 keV to 4 keV which has been successfully used on the OMEGA laser facility. The results of the radiant power measurements with the new MLM channel and with the usual channel composed of a thin titanium filter and a coaxial detector (without mirror) are compared. All elements of the channel have been calibrated in the laboratory of the Physikalisch-Technische Bundesanstalt, Germany's National Metrology Institute, at the synchrotron radiation facility BESSY II in Berlin using dedicated well established and validated methods.

  3. Improved measurement of the reactor antineutrino flux and spectrum at Daya Bay

    DOE PAGES

    An, F. P.; Balantekin, A. B.; Band, H. R.; ...

    2017-01-01

    Here, a new measurement of the reactor antineutrino flux and energy spectrum by the Daya Bay reactor neutrino experiment is reported. The antineutrinos were generated by six 2.9 GW th nuclear reactors and detected by eight antineutrino detectors deployed in two near (560 m and 600 m flux-weighted baselines) and one far (1640 m flux-weighted baseline) underground experimental halls. With 621 days of data, more than 1.2 million inverse beta decay (IBD) candidates were detected. The IBD yield in the eight detectors was measured, and the ratio of measured to predicted flux was found to be 0.946 ± 0.020 (0.992more » ± 0.021) for the Huber+Mueller (ILL+Vogel) model. A 2.9σ deviation was found in the measured IBD positron energy spectrum compared to the predictions. In particular, an excess of events in the region of 4$-$6 MeV was found in the measured spectrum, with a local significance of 4.4σ. Finally, a reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions.« less

  4. Anthropometric measures and absolute cardiovascular risk estimates in the Australian Diabetes, Obesity and Lifestyle (AusDiab) Study.

    PubMed

    Chen, Lei; Peeters, Anna; Magliano, Dianna J; Shaw, Jonathan E; Welborn, Timothy A; Wolfe, Rory; Zimmet, Paul Z; Tonkin, Andrew M

    2007-12-01

    Framingham risk functions are widely used for prediction of future cardiovascular disease events. They do not, however, include anthropometric measures of overweight or obesity, now considered a major cardiovascular disease risk factor. We aimed to establish the most appropriate anthropometric index and its optimal cutoff point for use as an ancillary measure in clinical practice when identifying people with increased absolute cardiovascular risk estimates. Analysis of a population-based, cross-sectional survey was carried out. The 1991 Framingham prediction equations were used to compute 5 and 10-year risks of cardiovascular or coronary heart disease in 7191 participants from the Australian Diabetes, Obesity and Lifestyle Study (1999-2000). Receiver operating characteristic curve analysis was used to compare measures of body mass index (BMI), waist circumference, and waist-to-hip ratio in identifying participants estimated to be at 'high', or at 'intermediate or high' absolute risk. After adjustment for BMI and age, waist-to-hip ratio showed stronger correlation with absolute risk estimates than waist circumference. The areas under the receiver operating characteristic curve for waist-to-hip ratio (0.67-0.70 in men, 0.64-0.74 in women) were greater than those for waist circumference (0.60-0.65, 0.59-0.71) or BMI (0.52-0.59, 0.53-0.66). The optimal cutoff points of BMI, waist circumference and waist-to-hip ratio to predict people at 'high', or at 'intermediate or high' absolute risk estimates were 26 kg/m2, 95 cm and 0.90 in men, and 25-26 kg/m2, 80-85 cm and 0.80 in women, respectively. Measurement of waist-to-hip ratio is more useful than BMI or waist circumference in the identification of individuals estimated to be at increased risk for future primary cardiovascular events.

  5. Elucidating Carbon Exchange at the Regional Scale Via Airborne Eddy Covariance Flux Measurements

    NASA Astrophysics Data System (ADS)

    Hannun, R. A.; Wolfe, G. M.; Kawa, S. R.; Newman, P. A.; Hanisco, T. F.; Diskin, G. S.; DiGangi, J. P.; Nowak, J. B.; Barrick, J. D. W.; Thornhill, K. L., II; Noormets, A.; Vargas, R.; Clark, K. L.; Kustas, W. P.

    2017-12-01

    Direct flux observations from aircraft provide a unique tool for probing greenhouse gas (GHG) sources and sinks on a regional scale. Airborne eddy covariance, which relies on high-frequency, simultaneous measurements of fluctuations in concentration and vertical wind speed, is a robust method for quantifying surface-atmosphere exchange. We have assembled and flown an instrument payload onboard the NASA C-23 Sherpa aircraft capable of measuring CO2, CH4, H2O, and heat fluxes. Flights for the Carbon Airborne Flux Experiment (CARAFE) took place during September 2016 and May 2017 based out of Wallops Flight Facility, VA. Flight tracks covered a variety of ecosystems and land-use types in the Mid-Atlantic, including forests, croplands, and wetlands. Carbon fluxes are derived using eddy covariance and wavelet analysis. Our results show a strong drawdown of CO2 and near-zero CH4 emissions from crops and dry-land forest, but seasonally strong CH4 flux from wetland forest. CARAFE flux data will also be compared with observations from several flux towers along the flight path to complement the airborne measurements. We will further assess the effects of land surface type and seasonal variability in carbon exchange. Regional-scale flux observations from CARAFE supply a useful constraint for improving top-down and bottom up estimates of carbon sources and sinks.

  6. Long-lived neutral-kaon flux measurement for the KOTO experiment

    DOE PAGES

    Masuda, T.; Ahn, J. K.; Banno, S.; ...

    2016-01-24

    The KOTO(K 0 at Tokai) experiment aims to observe the CP-violating rare decay K L → π 0νν¯ over bar by using a long-lived neutral-kaon beam produced by the 30 GeV proton beam at the Japan Proton Accelerator Research Complex. The K L flux is an essential parameter for the measurement of the branching fraction. Three K L neutral decay modes, K L → 3 π 0, K L → 2 π 0, and K L → 2γ, were used to measure the K L flux in the beam line in the 2013 KOTO engineering run. A Monte Carlo simulationmore » was used to estimate the detector acceptance for these decays. Agreement was found between the simulation model and the experimental data, and the remaining systematic uncertainty was estimated at the 1.4% level. Here, the K L flux was measured as (4.183 ± 0.017 stat. ± 0.059 sys.) x 10 7 K L per 2 x 10 14 protons on a 66-mm-long Au target.« less

  7. Measurement of the absolute branching fraction of D0-->K-pi+.

    PubMed

    Aubert, B; Bona, M; Boutigny, D; Karyotakis, Y; Lees, J P; Poireau, V; Prudent, X; Tisserand, V; Zghiche, A; Garra Tico, J; Grauges, E; Lopez, L; Palano, A; Eigen, G; Ofte, I; Stugu, B; Sun, L; Abrams, G S; Battaglia, M; Brown, D N; Button-Shafer, J; Cahn, R N; Groysman, Y; Jacobsen, R G; Kadyk, J A; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lopes Pegna, D; Lynch, G; Mir, L M; Orimoto, T J; Pripstein, M; Roe, N A; Ronan, M T; Tackmann, K; Wenzel, W A; Del Amo Sanchez, P; Hawkes, C M; Watson, A T; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Schroeder, T; Steinke, M; Cottingham, W N; Walker, D; Asgeirsson, D J; Cuhadar-Donszelmann, T; Fulsom, B G; Hearty, C; Knecht, N S; Mattison, T S; McKenna, J A; Khan, A; Saleem, M; Teodorescu, L; Blinov, V E; Bukin, A D; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, K Yu; Bondioli, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M; Martin, E C; Stoker, D P; Abachi, S; Buchanan, C; Foulkes, S D; Gary, J W; Liu, F; Long, O; Shen, B C; Zhang, L; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Cunha, A; Dahmes, B; Hong, T M; Kovalskyi, D; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Schalk, T; Schumm, B A; Seiden, A; Williams, D C; Wilson, M G; Winstrom, L O; Chen, E; Cheng, C H; Dvoretskii, A; Fang, F; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Mancinelli, G; Meadows, B T; Mishra, K; Sokoloff, M D; Blanc, F; Bloom, P C; Chen, S; Ford, W T; Hirschauer, J F; Kreisel, A; Nagel, M; Nauenberg, U; Olivas, A; Smith, J G; Ulmer, K A; Wagner, S R; Zhang, J; Gabareen, A M; Soffer, A; Toki, W H; Wilson, R J; Winklmeier, F; Zeng, Q; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Merkel, J; Petzold, A; Spaan, B; Wacker, K; Brandt, T; Klose, V; Lacker, H M; Mader, W F; Nogowski, R; Schubert, J; Schubert, K R; Schwierz, R; Sundermann, J E; Volk, A; Bernard, D; Bonneaud, G R; Latour, E; Lombardo, V; Thiebaux, Ch; Verderi, M; Clark, P J; Gradl, W; Muheim, F; Playfer, S; Robertson, A I; Xie, Y; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cecchi, A; Cibinetto, G; Franchini, P; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Prencipe, E; Santoro, V; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Contri, R; Lo Vetere, M; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Chaisanguanthum, K S; Morii, M; Wu, J; Dubitzky, R S; Marks, J; Schenk, S; Uwer, U; Bard, D J; Dauncey, P D; Flack, R L; Nash, J A; Nikolich, M B; Panduro Vazquez, W; Behera, P K; Chai, X; Charles, M J; Mallik, U; Meyer, N T; Ziegler, V; Cochran, J; Crawley, H B; Dong, L; Eyges, V; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gritsan, A V; Guo, Z J; Lae, C K; Denig, A G; Fritsch, M; Schott, G; Arnaud, N; Béquilleux, J; Davier, M; Grosdidier, G; Höcker, A; Lepeltier, V; Le Diberder, F; Lutz, A M; Pruvot, S; Rodier, S; Roudeau, P; Schune, M H; Serrano, J; Sordini, V; Stocchi, A; Wang, W F; Wormser, G; Lange, D J; Wright, D M; Chavez, C A; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; Hutchcroft, D E; Payne, D J; Schofield, K C; Touramanis, C; Bevan, A J; George, K A; Di Lodovico, F; Menges, W; Sacco, R; Cowan, G; Flaecher, H U; Hopkins, D A; Jackson, P S; McMahon, T R; Salvatore, F; Wren, A C; Brown, D N; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Chia, Y M; Edgar, C L; Lafferty, G D; West, T J; Yi, J I; Anderson, J; Chen, C; Jawahery, A; Roberts, D A; Simi, G; Tuggle, J M; Blaylock, G; Dallapiccola, C; Hertzbach, S S; Li, X; Moore, T B; Salvati, E; Saremi, S; Cowan, R; Fisher, P H; Sciolla, G; Sekula, S J; Spitznagel, M; Taylor, F; Yamamoto, R K; McLachlin, S E; Patel, P M; Robertson, S H; Lazzaro, A; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Simard, M; Taras, P; Viaud, F B; Nicholson, H; De Nardo, G; Fabozzi, F; Lista, L; Monorchio, D; Sciacca, C; Baak, M A; Raven, G; Snoek, H L; Jessop, C P; Losecco, J M; Benelli, G; Corwin, L A; Gan, K K; Honscheid, K; Hufnagel, D; Kagan, H; Kass, R; Morris, J P; Rahimi, A M; Regensburger, J J; Ter-Antonyan, R; Wong, Q K; Blount, N L; Brau, J; Frey, R; Igonkina, O; Kolb, J A; Lu, M; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Gagliardi, N; Gaz, A; Margoni, M; Morandin, M; Pompili, A; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Ben-Haim, E; Briand, H; Chauveau, J; David, P; Del Buono, L; de la Vaissière, Ch; Hamon, O; Hartfiel, B L; Leruste, Ph; Malclès, J; Ocariz, J; Perez, A; Gladney, L; Biasini, M; Covarelli, R; Manoni, E; Angelini, C; Batignani, G; Bettarini, S; Calderini, G; Carpinelli, M; Cenci, R; Cervelli, A; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Mazur, M A; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Haire, M; Biesiada, J; Elmer, P; Lau, Y P; Lu, C; Olsen, J; Smith, A J S; Telnov, A V; Baracchini, E; Bellini, F; Cavoto, G; D'Orazio, A; Del Re, D; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Jackson, P D; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Renga, F; Voena, C; Ebert, M; Schröder, H; Waldi, R; Adye, T; Castelli, G; Franek, B; Olaiya, E O; Ricciardi, S; Roethel, W; Wilson, F F; Aleksan, R; Emery, S; Escalier, M; Gaidot, A; Ganzhur, S F; de Monchenault, G Hamel; Kozanecki, W; Legendre, M; Vasseur, G; Yèche, Ch; Zito, M; Chen, X R; Liu, H; Park, W; Purohit, M V; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Berger, N; Claus, R; Coleman, J P; Convery, M R; Dingfelder, J C; Dorfan, J; Dubois-Felsmann, G P; Dujmic, D; Dunwoodie, W; Field, R C; Glanzman, T; Gowdy, S J; Graham, M T; Grenier, P; Hast, C; Hryn'ova, T; Innes, W R; Kelsey, M H; Kim, H; Kim, P; Leith, D W G S; Li, S; Luitz, S; Luth, V; Lynch, H L; Macfarlane, D B; Marsiske, H; Messner, R; Muller, D R; O'Grady, C P; Perazzo, A; Perl, M; Pulliam, T; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Stelzer, J; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Va'vra, J; van Bakel, N; Wagner, A P; Weaver, M; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Yi, K; Young, C C; Burchat, P R; Edwards, A J; Majewski, S A; Petersen, B A; Wilden, L; Ahmed, S; Alam, M S; Bula, R; Ernst, J A; Jain, V; Pan, B; Saeed, M A; Wappler, F R; Zain, S B; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Ritchie, J L; Ruland, A M; Schilling, C J; Schwitters, R F; Izen, J M; Lou, X C; Ye, S; Bianchi, F; Gallo, F; Gamba, D; Pelliccioni, M; Bomben, M; Bosisio, L; Cartaro, C; Cossutti, F; Della Ricca, G; Lanceri, L; Vitale, L; Azzolini, V; Lopez-March, N; Martinez-Vidal, F; Milanes, D A; Oyanguren, A; Albert, J; Banerjee, Sw; Bhuyan, B; Hamano, K; Kowalewski, R; Nugent, I M; Roney, J M; Sobie, R J; Back, J J; Harrison, P F; Latham, T E; Mohanty, G B; Pappagallo, M; Band, H R; Chen, X; Dasu, S; Flood, K T; Hollar, J J; Kutter, P E; Pan, Y; Pierini, M; Prepost, R; Wu, S L; Yu, Z; Neal, H

    2008-02-08

    We measure the absolute branching fraction for D(0)-->K(-)pi(+) using partial reconstruction of B(0)-->D(*+)Xl(-)nu(l) decays, in which only the charged lepton and the pion from the decay D(*+)-->D(0)pi(+) are used. Based on a data sample of 230 x 10(6) BB pairs collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC, we obtain B(D(0)-->K(-)pi(+)) = (4.007+/-0.037+/-0.072)%, where the first uncertainty is statistical and the second is systematic.

  8. Catheter-Based Measurements of Absolute Coronary Blood Flow and Microvascular Resistance: Feasibility, Safety, and Reproducibility in Humans.

    PubMed

    Xaplanteris, Panagiotis; Fournier, Stephane; Keulards, Daniëlle C J; Adjedj, Julien; Ciccarelli, Giovanni; Milkas, Anastasios; Pellicano, Mariano; Van't Veer, Marcel; Barbato, Emanuele; Pijls, Nico H J; De Bruyne, Bernard

    2018-03-01

    The principle of continuous thermodilution can be used to calculate absolute coronary blood flow and microvascular resistance (R). The aim of the study is to explore the safety, feasibility, and reproducibility of coronary blood flow and R measurements as measured by continuous thermodilution in humans. Absolute coronary flow and R can be calculated by thermodilution by infusing saline at room temperature through a dedicated monorail catheter. The temperature of saline as it enters the vessel, the temperature of blood and saline mixed in the distal part of the vessel, and the distal coronary pressure were measured by a pressure/temperature sensor-tipped guidewire. The feasibility and safety of the method were tested in 135 patients who were referred for coronary angiography. No significant adverse events were observed; in 11 (8.1%) patients, bradycardia and concomitant atrioventricular block appeared transiently and were reversed immediately on interruption of the infusion. The reproducibility of measurements was tested in a subgroup of 80 patients (129 arteries). Duplicate measurements had a strong correlation both for coronary blood flow (ρ=0.841, P <0.001; intraclass correlation coefficient=0.89, P <0.001) and R (ρ=0.780, P <0.001; intraclass correlation coefficient=0.89, P <0.001). In Bland-Altman plots, there was no significant bias or asymmetry. Absolute coronary blood flow (in L/min) and R (in mm Hg/L/min or Wood units) can be safely and reproducibly measured with continuous thermodilution. This approach constitutes a new opportunity for the study of the coronary microcirculation. © 2018 American Heart Association, Inc.

  9. Eddy correlation measurements of size-dependent cloud droplet turbulent fluxes to complex terrain

    NASA Astrophysics Data System (ADS)

    Vong, Richard J.; Kowalski, Andrew S.

    1995-07-01

    An eddy correlation technique was used to measure the turbulent flux of cloud droplets to complex, forested terrain near the coast of Washington State during the spring of 1993. Excellent agreement was achieved for cloud liquid water content measured by two instruments. Substantial downward liquid water fluxes of ~ 1mm per 24 h were measured at night during "steady and continuous" cloud events, about twice the magnitude of those measured by Beswick etal. in Scotland. Cloud water chemical fluxes were estimated to represent up to 50% of the chemical deposition associated with precipitation at the site. An observed size-dependence in the turbulent liquid water fluxes suggested that both droplet impaction, which leads to downward fluxes, and phase change processes, which can lead to upward fluxes, consistently are important contributors to the eddy correlation results. The diameter below which phase change processes were important to observed fluxes was shown to depend upon σLL, the relative standard deviation of the liquid water content (LWC) within a 30-min averaging period. The crossover from upward to downward LW flux occurs at 8µm for steady and continuous cloud events but at ~ 13µm for events with a larger degree of LWC variability. This comparison of the two types of cloud events suggested that evaporation was the most likely cause of upward droplet fluxes for the smaller droplets (dia<13µm) during cloud with variable LWC (σLL>0.3).

  10. Measurement of high-energy neutron flux above ground utilizing a spallation based multiplicity technique

    DOE PAGES

    Roecker, Caleb; Bernstein, Adam; Marleau, Peter; ...

    2016-11-14

    Cosmogenic high-energy neutrons are a ubiquitous, difficult to shield, poorly measured background. Above ground the high-energy neutron energy-dependent flux has been measured, with significantly varying results. Below ground, high-energy neutron fluxes are largely unmeasured. Here we present a reconstruction algorithm to unfold the incident neutron energy-dependent flux measured using the Multiplicity and Recoil Spectrometer (MARS), simulated test cases to verify the algorithm, and provide a new measurement of the above ground high-energy neutron energy-dependent flux with a detailed systematic uncertainty analysis. Uncertainty estimates are provided based upon the measurement statistics, the incident angular distribution, the surrounding environment of the Montemore » Carlo model, and the MARS triggering efficiency. Quantified systematic uncertainty is dominated by the assumed incident neutron angular distribution and surrounding environment of the Monte Carlo model. The energy-dependent neutron flux between 90 MeV and 400 MeV is reported. Between 90 MeV and 250 MeV the MARS results are comparable to previous Bonner sphere measurements. Over the total energy regime measured, the MARS result are located within the span of previous measurements. Lastly, these results demonstrate the feasibility of future below ground measurements with MARS.« less

  11. Measurement of high-energy neutron flux above ground utilizing a spallation based multiplicity technique

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Roecker, Caleb; Bernstein, Adam; Marleau, Peter

    Cosmogenic high-energy neutrons are a ubiquitous, difficult to shield, poorly measured background. Above ground the high-energy neutron energy-dependent flux has been measured, with significantly varying results. Below ground, high-energy neutron fluxes are largely unmeasured. Here we present a reconstruction algorithm to unfold the incident neutron energy-dependent flux measured using the Multiplicity and Recoil Spectrometer (MARS), simulated test cases to verify the algorithm, and provide a new measurement of the above ground high-energy neutron energy-dependent flux with a detailed systematic uncertainty analysis. Uncertainty estimates are provided based upon the measurement statistics, the incident angular distribution, the surrounding environment of the Montemore » Carlo model, and the MARS triggering efficiency. Quantified systematic uncertainty is dominated by the assumed incident neutron angular distribution and surrounding environment of the Monte Carlo model. The energy-dependent neutron flux between 90 MeV and 400 MeV is reported. Between 90 MeV and 250 MeV the MARS results are comparable to previous Bonner sphere measurements. Over the total energy regime measured, the MARS result are located within the span of previous measurements. Lastly, these results demonstrate the feasibility of future below ground measurements with MARS.« less

  12. Preliminary OARE absolute acceleration measurements on STS-50

    NASA Technical Reports Server (NTRS)

    Blanchard, Robert C.; Nicholson, John Y.; Ritter, James

    1993-01-01

    On-orbit Orbital Acceleration Research Experiment (OARE) data on STS-50 was examined in detail during a 2-day time period. Absolute acceleration levels were derived at the OARE location, the orbiter center-of-gravity, and at the STS-50 spacelab Crystal Growth Facility. The tri-axial OARE raw acceleration measurements (i.e., telemetered data) during the interval were filtered using a sliding trimmed mean filter in order to remove large acceleration spikes (e.g., thrusters) and reduce the noise. Twelve OARE measured biases in each acceleration channel during the 2-day interval were analyzed and applied to the filtered data. Similarly, the in situ measured x-axis scale factors in the sensor's most sensitive range were also analyzed and applied to the data. Due to equipment problem(s) on this flight, both y- and z- axis sensitive range scale factors were determined in a separate process (using the OARE maneuver data) and subsequently applied to the data. All known significant low-frequency corrections at the OARE location (i.e., both vertical and horizontal gravity-gradient, and rotational effects) were removed from the filtered data in order to produce the acceleration components at the orbiter's center-of-gravity, which are the aerodynamic signals along each body axes. Results indicate that there is a force of unknown origin being applied to the Orbiter in addition to the aerodynamic forces. The OARE instrument and all known gravitational and electromagnetic forces were reexamined, but none produce the observed effect. Thus, it is tentatively concluded that the Orbiter is creating the environment observed.

  13. A new method to calibrate the absolute sensitivity of a soft X-ray streak camera

    NASA Astrophysics Data System (ADS)

    Yu, Jian; Liu, Shenye; Li, Jin; Yang, Zhiwen; Chen, Ming; Guo, Luting; Yao, Li; Xiao, Shali

    2016-12-01

    In this paper, we introduce a new method to calibrate the absolute sensitivity of a soft X-ray streak camera (SXRSC). The calibrations are done in the static mode by using a small laser-produced X-ray source. A calibrated X-ray CCD is used as a secondary standard detector to monitor the X-ray source intensity. In addition, two sets of holographic flat-field grating spectrometers are chosen as the spectral discrimination systems of the SXRSC and the X-ray CCD. The absolute sensitivity of the SXRSC is obtained by comparing the signal counts of the SXRSC to the output counts of the X-ray CCD. Results show that the calibrated spectrum covers the range from 200 eV to 1040 eV. The change of the absolute sensitivity in the vicinity of the K-edge of the carbon can also be clearly seen. The experimental values agree with the calculated values to within 29% error. Compared with previous calibration methods, the proposed method has several advantages: a wide spectral range, high accuracy, and simple data processing. Our calibration results can be used to make quantitative X-ray flux measurements in laser fusion research.

  14. Nightside electron flux measurements at Mars by the Phobos-2 HARP instrument

    NASA Technical Reports Server (NTRS)

    Shutte, N.; Gringauz, K.; Kiraly, P.; Kotova, G.; Nagy, A. F.; Rosenbauer, H.; Szego, K.; Verigin, M.

    1995-01-01

    All the available nightside electron data obtained during circular orbits at Mars from the Phobos-2 Hyperbolic Retarded Potential Analyzer (HARP) instrument have been examined in detail and are summarized in this paper. An electron flux component with energies exceeding that of the unperturbed solar wind was observed inside the magnetosheath, indicating the presence of acceleration mechanism(s). The character of the electron fluxes measured in the magnetotail cannot be classified in any simple manner, however, there is a correlation between the electron fluxes measured well inside this region and the unperturbed solar wind ram pressure.

  15. AmeriFlux: Measuring carbon, water and energy flux across the Americas.

    Science.gov Websites

    Sign In × Welcome Close POSTCARDS Register for the 2018 AmeriFlux Synthesis Workshop! US-UMB AmeriFlux tower, located at the University of Michigan Biological Station (UMBS) Decadal Synthesis Survey POSTCARDS Register for the 2018 AmeriFlux Synthesis Workshop! Apr 2 2018 Decadal Synthesis Survey: Insights

  16. Method and apparatus for making absolute range measurements

    DOEpatents

    Allison, Stephen W.; Cates, Michael R.; Key, William S.; Sanders, Alvin J.; Earl, Dennis D.

    1999-01-01

    This invention relates to a method and apparatus for making absolute distance or ranging measurements using Fresnel diffraction. The invention employs a source of electromagnetic radiation having a known wavelength or wavelength distribution, which sends a beam of electromagnetic radiation through an object which causes it to be split (hereinafter referred to as a "beamsplitter"), and then to a target. The beam is reflected from the target onto a screen containing an aperture spaced a known distance from the beamsplitter. The aperture is sized so as to produce a Fresnel diffraction pattern. A portion of the beam travels through the aperture to a detector, spaced a known distance from the screen. The detector detects the central intensity of the beam. The distance from the object which causes the beam to be split to the target can then be calculated based upon the known wavelength, aperture radius, beam intensity, and distance from the detector to the screen. Several apparatus embodiments are disclosed for practicing the method embodiments of the present invention.

  17. Method and apparatus for making absolute range measurements

    DOEpatents

    Allison, S.W.; Cates, M.R.; Key, W.S.; Sanders, A.J.; Earl, D.D.

    1999-06-22

    This invention relates to a method and apparatus for making absolute distance or ranging measurements using Fresnel diffraction. The invention employs a source of electromagnetic radiation having a known wavelength or wavelength distribution, which sends a beam of electromagnetic radiation through an object which causes it to be split (hereinafter referred to as a beam splitter''), and then to a target. The beam is reflected from the target onto a screen containing an aperture spaced a known distance from the beam splitter. The aperture is sized so as to produce a Fresnel diffraction pattern. A portion of the beam travels through the aperture to a detector, spaced a known distance from the screen. The detector detects the central intensity of the beam. The distance from the object which causes the beam to be split to the target can then be calculated based upon the known wavelength, aperture radius, beam intensity, and distance from the detector to the screen. Several apparatus embodiments are disclosed for practicing the method embodiments of the present invention. 9 figs.

  18. Motion-Correlated Flow Distortion and Wave-Induced Biases in Air-Sea Flux Measurements From Ships

    NASA Astrophysics Data System (ADS)

    Prytherch, J.; Yelland, M. J.; Brooks, I. M.; Tupman, D. J.; Pascal, R. W.; Moat, B. I.; Norris, S. J.

    2016-02-01

    Direct measurements of the turbulent air-sea fluxes of momentum, heat, moisture and gases are often made using sensors mounted on ships. Ship-based turbulent wind measurements are corrected for platform motion using well established techniques, but biases at scales associated with wave and platform motion are often still apparent in the flux measurements. It has been uncertain whether this signal is due to time-varying distortion of the air flow over the platform, or to wind-wave interactions impacting the turbulence. Methods for removing such motion-scale biases from scalar measurements have previously been published but their application to momentum flux measurements remains controversial. Here we use eddy covariance momentum flux measurements obtained onboard RRS James Clark Ross as part of the Waves, Aerosol and Gas Exchange Study (WAGES), a programme of near-continuous measurements using the autonomous AutoFlux system (Yelland et al., 2009). Measurements were made in 2013 in locations throughout the North and South Atlantic, the Southern Ocean and the Arctic Ocean, at latitudes ranging from 62°S to 75°N. We show that the measured motion-scale bias has a dependence on the horizontal ship velocity, and that a correction for it reduces the dependence of the measured momentum flux on the orientation of the ship to the wind. We conclude that the bias is due to experimental error, and that time-varying motion-dependent flow distortion is the likely source. Yelland, M., Pascal, R., Taylor, P. and Moat, B.: AutoFlux: an autonomous system for the direct measurement of the air-sea fluxes of CO2, heat and momentum. J. Operation. Oceanogr., 15-23, doi:10.1080/1755876X.2009.11020105, 2009.

  19. Measurement of Turbulent Water Vapor Fluxes from Lightweight Unmanned Aircraft Systems

    NASA Astrophysics Data System (ADS)

    Thomas, R. M.; Ramanathan, V.; Nguyen, H.; Lehmann*, K.

    2010-12-01

    Scientists at the Center for Clouds, Chemistry and Climate (C4) at the Scripps Institution of Oceanography have successfully used Unmanned Aircraft Systems (UASs) for measurements of radiation fluxes, aerosol concentrations and cloud microphysical properties. Building on this success, a payload to measure water vapor fluxes using the eddy covariance (EC) technique has been recently developed and tested. To our knowledge this is the first UAS turbulent flux system to incorporate high-frequency water vapor measurements. The driving aim of the water vapor flux system’s development is to investigate ‘atmospheric rivers’ in the north-western Pacific Ocean, these can lead to sporadic yet extreme rainfall and flooding events upon landfall in California. Such a flux system may also be used to investigate other weather events (e.g. the formation of hurricanes) and offers a powerful aerosol-cloud-radiative forcing investigative tool when combined with the existing aerosol/radiation and cloud microphysics UAS payloads. The atmospheric vertical wind component (w) is derived by this system at up to 100Hz using data from a GPS/Inertial Measurement Unit (GPS/IMU) combined with a fast-response gust probe mounted on the UAV. Measurements of w are then combined with equally high frequency water vapor data (collected using a Campbell Scientific Krypton Hygrometer) to calculate latent heat fluxes (λE). Two test flights were conducted at the NASA Dryden test facility on 27th May 2010, located in the Mojave Desert. Horizontal flight legs were recorded at four altitudes between 1000-2500 masl within the convective boundary layer. Preliminary data analysis indicates averaged spectral data follow the theoretical -5/3 slope , and extrapolation of the flux profile to the surface resulted in λE of 1.6 W m-2; in good agreement with 1.0 W m-2 λE measured by NOAA from a surface tower using standard flux techniques. The system performance during the Dryden test, as well as subsequent

  20. Shortwave Radiative Fluxes, Solar-Beam Transmissions, and Aerosol Properties: TARFOX and ACE-2 Find More Absorption from Flux Radiometry than from Other Measurements

    NASA Technical Reports Server (NTRS)

    Russell, Philip B.; Redemann, J.; Schmid, B.; Livingston, J. M.; Bergstrom, R. W.; Ramirez, S. A.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    The Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) and the Second Aerosol Characterization Experiment (ACE-2) made simultaneous measurements of shortwave radiative fluxes, solar-beam transmissions, and the aerosols affecting those fluxes and transmissions. Besides the measured fluxes and transmissions, other obtained properties include aerosol scattering and absorption measured in situ at the surface and aloft; aerosol single scattering albedo retrieved from skylight radiances; and aerosol complex refractive index derived by combining profiles of backscatter, extinction, and size distribution. These measurements of North Atlantic boundary layer aerosols impacted by anthropogenic pollution revealed the following characteristic results: (1) Better agreement among different types of remote measurements of aerosols (e.g., optical depth, extinction, and backscattering from sunphotometers, satellites, and lidars) than between remote and in situ measurements; 2) More extinction derived from transmission measurements than from in situ measurements; (3) Larger aerosol absorption inferred from flux radiometry than from other measurements. When the measured relationships between downwelling flux and optical depth (or beam transmission) are used to derive best-fit single scattering albedos for the polluted boundary layer aerosol, both TARFOX and ACE-2 yield midvisible values of 0.90 +/- 0.04. The other techniques give larger single scattering albedos (i.e. less absorption) for the polluted boundary layer, with a typical result of 0.95 +/- 0.04. Although the flux-based results have the virtue of describing the column aerosol unperturbed by sampling, they are subject to questions about representativeness and other uncertainties (e.g., unknown gas absorption). Current uncertainties in aerosol single scattering albedo are large in terms of climate effects. They also have an important influence on aerosol optical depths retrieved from satellite radiances

  1. Absolute calibration of sniffer probes on Wendelstein 7-X

    NASA Astrophysics Data System (ADS)

    Moseev, D.; Laqua, H. P.; Marsen, S.; Stange, T.; Braune, H.; Erckmann, V.; Gellert, F.; Oosterbeek, J. W.

    2016-08-01

    Here we report the first measurements of the power levels of stray radiation in the vacuum vessel of Wendelstein 7-X using absolutely calibrated sniffer probes. The absolute calibration is achieved by using calibrated sources of stray radiation and the implicit measurement of the quality factor of the Wendelstein 7-X empty vacuum vessel. Normalized absolute calibration coefficients agree with the cross-calibration coefficients that are obtained by the direct measurements, indicating that the measured absolute calibration coefficients and stray radiation levels in the vessel are valid. Close to the launcher, the stray radiation in the empty vessel reaches power levels up to 340 kW/m2 per MW injected beam power. Furthest away from the launcher, i.e., half a toroidal turn, still 90 kW/m2 per MW injected beam power is measured.

  2. Absolute calibration of sniffer probes on Wendelstein 7-X.

    PubMed

    Moseev, D; Laqua, H P; Marsen, S; Stange, T; Braune, H; Erckmann, V; Gellert, F; Oosterbeek, J W

    2016-08-01

    Here we report the first measurements of the power levels of stray radiation in the vacuum vessel of Wendelstein 7-X using absolutely calibrated sniffer probes. The absolute calibration is achieved by using calibrated sources of stray radiation and the implicit measurement of the quality factor of the Wendelstein 7-X empty vacuum vessel. Normalized absolute calibration coefficients agree with the cross-calibration coefficients that are obtained by the direct measurements, indicating that the measured absolute calibration coefficients and stray radiation levels in the vessel are valid. Close to the launcher, the stray radiation in the empty vessel reaches power levels up to 340 kW/m(2) per MW injected beam power. Furthest away from the launcher, i.e., half a toroidal turn, still 90 kW/m(2) per MW injected beam power is measured.

  3. Using passive capillary lysimeter water flux measurements to improve flow predictions in variably saturated soils.

    USDA-ARS?s Scientific Manuscript database

    Passive capillary lysimeters (PCLs) are uniquely suited for measuring water fluxes in variably-saturated soils. The objective of this work was to compare PCL flux measurements with simulated fluxes obtained with a calibrated unsaturated flow model. The Richards equation-based model was calibrated us...

  4. A mobile detector for measurements of the atmospheric muon flux

    NASA Astrophysics Data System (ADS)

    Mitrica, B.; Brancus, I. M.; Margineanu, R.; Petcu, M.; Dima, M.; Sima, O.; Haungs, A.; Rebel, H.; Petre, M.; Toma, G.; Saftoiu, A.; Apostu, A.

    2011-04-01

    Measurements of the underground atmospheric muon flux are important in order to determine accurately the overburden in mwe (meter water equivalent) of an underground laboratory for appreciating which kind of experiments are feasible for that location. Slanic- Prohava is one of the 7 possible locations for the European large underground experiment LAGUNA (Large Apparatus studying Grand Unification and Neutrino Astrophysics). A mobile device consisting of 2 scintillator plates (≍0.9 m2, each) one above the other and measuring in coincidence, was set-up for determining the muon flux. The detector it is installed on a van which facilitates measurements on different positions at the surface or in the underground and it is in operation since autumn 2009. The measurements of muon fluxes presented in this contribution have been performed in the underground salt mine Slanic-Prahova, Romania, where IFIN-HH has built a low radiation level laboratory, and at the surface on different sites of Romania, at different elevations from 0 m a.s.l up to 655 m a.s.l. Based on our measurements we can say that Slanic site is a feasible location for LAGUNA in Unirea salt mine at a water equivalent depth of 600 mwe. The results have been compared with Monte-Carlo simulations performed with the simulation codes CORSIKA and MUSIC.

  5. Measurement of absolute laser energy absorption by nano-structured targets

    NASA Astrophysics Data System (ADS)

    Park, Jaebum; Tommasini, R.; London, R.; Bargsten, C.; Hollinger, R.; Capeluto, M. G.; Shlyaptsev, V. N.; Rocca, J. J.

    2017-10-01

    Nano-structured targets have been reported to allow the realization of extreme plasma conditions using table top lasers, and have gained much interest as a platform to investigate the ultra-high energy density plasmas (>100 MJ/cm3) . One reason for these targets to achieve extreme conditions is increased laser energy absorption (LEA). The absolute LEA by nano-structured targets has been measured for the first time and compared to that by foil targets. The experimental results, including the effects of target parameters on the LEA, will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52097NA27344, and funded by LDRD (#15-ERD-054).

  6. Inter-comparison of Flux-Gradient and Relaxed Eddy Accumulation Methods for Measuring Ammonia Flux Above a Corn Canopy in Central Illinois, USA

    NASA Astrophysics Data System (ADS)

    Nelson, A. J.; Koloutsou-Vakakis, S.; Rood, M. J.; Lichiheb, N.; Heuer, M.; Myles, L.

    2017-12-01

    Ammonia (NH3) is a precursor to fine particulate matter (PM) in the ambient atmosphere. Agricultural activities represent over 80% of anthropogenic emissions of NH3 in the United States. The use of nitrogen-based fertilizers contribute > 50% of total NH3 emissions in central Illinois. The U.S. EPA Science Advisory Board has called for improved methods to measure, model, and report atmospheric NH3 concentrations and emissions from agriculture. High uncertainties in the temporal and spatial distribution of NH3 emissions contribute to poor performance of air quality models in predicting ambient PM concentrations. This study reports and compares NH­3 flux measurements of differing temporal resolution obtained with two methods: relaxed eddy accumulation (REA) and flux-gradient (FG). REA and FG systems were operated concurrently above a corn canopy at the University of Illinois at Urbana-Champaign (UIUC) Energy Biosciences Institute (EBI) Energy Farm during the 2014 corn-growing season. The REA system operated during daytime, providing average fluxes over four-hour sampling intervals, where time resolution was limited by detection limit of denuders. The FG system employed a cavity ring-down spectrometer, and was operated continuously, reporting 30 min flux averages. A flux-footprint evaluation was used for quality control, resulting in 1,178 qualified FG measurements, 82 of which were coincident with REA measurements. Similar emission trends were observed with both systems, with peak NH3 emission observed one week after fertilization. For all coincident samples, mean NH3 flux was 205 ± 300 ng-N-m2s-1 and 110 ± 256 ng-N-m2s-1 as measured with REA and FG, respectively, where positive flux indicates emission. This is the first reported inter-comparison of REA and FG methods as used for quantifying NH3 fluxes from cropland. Preliminary analysis indicates the improved temporal resolution and continuous sampling enabled by FG allow for the identification of emission pulses

  7. Heat-Flux Measurements in Laser-Produced Plasmas Using Thomson Scattering from Electron Plasma Waves

    NASA Astrophysics Data System (ADS)

    Henchen, R. J.; Goncharov, V. N.; Cao, D.; Katz, J.; Froula, D. H.; Rozmus, W.

    2017-10-01

    An experiment was designed to measure heat flux in coronal plasmas using collective Thomson scattering. Adjustments to the electron distribution function resulting from heat flux affect the shape of the collective Thomson scattering features through wave-particle resonance. The amplitude of the Spitzer-Härm electron distribution function correction term (f1) was varied to match the data and determines the value of the heat flux. Independent measurements of temperature and density obtained from Thomson scattering were used to infer the classical heat flux (q = - κ∇Te) . Time-resolved Thomson-scattering data were obtained at five locations in the corona along the target normal in a blowoff plasma formed from a planar Al target with 1.5 kJ of 351-nm laser light in a 2-ns square pulse. The flux measured through the Thomson-scattering spectra is a factor of 5 less than the κ∇Te measurements. The lack of collisions of heat-carrying electrons suggests a nonlocal model is needed to accurately describe the heat flux. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  8. Cosmic muon flux measurements at the Kimballton Underground Research Facility

    NASA Astrophysics Data System (ADS)

    Kalousis, L. N.; Guarnaccia, E.; Link, J. M.; Mariani, C.; Pelkey, R.

    2014-08-01

    In this article, the results from a series of muon flux measurements conducted at the Kimballton Underground Research Facility (KURF), Virginia, United States, are presented. The detector employed for these investigations, is made of plastic scintillator bars readout by wavelength shifting fibers and multianode photomultiplier tubes. Data was taken at several locations inside KURF, spanning rock overburden values from ~ 200 to 1450 m.w.e. From the extracted muon rates an empirical formula was devised, that estimates the muon flux inside the mine as a function of the overburden. The results are in good agreement with muon flux calculations based on analytical models and MUSIC.

  9. Measurement of the Reactor Antineutrino Flux and Spectrum at Daya Bay

    NASA Astrophysics Data System (ADS)

    An, F. P.; Balantekin, A. B.; Band, H. R.; Bishai, M.; Blyth, S.; Butorov, I.; Cao, D.; Cao, G. F.; Cao, J.; Cen, W. R.; Chan, Y. L.; Chang, J. F.; Chang, L. C.; Chang, Y.; Chen, H. S.; Chen, Q. Y.; Chen, S. M.; Chen, Y. X.; Chen, Y.; Cheng, J. H.; Cheng, J.; Cheng, Y. P.; Cherwinka, J. J.; Chu, M. C.; Cummings, J. P.; de Arcos, J.; Deng, Z. Y.; Ding, X. F.; Ding, Y. Y.; Diwan, M. V.; Dove, J.; Draeger, E.; Dwyer, D. A.; Edwards, W. R.; Ely, S. R.; Gill, R.; Gonchar, M.; Gong, G. H.; Gong, H.; Grassi, M.; Gu, W. Q.; Guan, M. Y.; Guo, L.; Guo, X. H.; Hackenburg, R. W.; Han, R.; Hans, S.; He, M.; Heeger, K. M.; Heng, Y. K.; Higuera, A.; Hor, Y. K.; Hsiung, Y. B.; Hu, B. Z.; Hu, L. M.; Hu, L. J.; Hu, T.; Hu, W.; Huang, E. C.; Huang, H. X.; Huang, X. T.; Huber, P.; Hussain, G.; Jaffe, D. E.; Jaffke, P.; Jen, K. L.; Jetter, S.; Ji, X. P.; Ji, X. L.; Jiao, J. B.; Johnson, R. A.; Kang, L.; Kettell, S. H.; Kohn, S.; Kramer, M.; Kwan, K. K.; Kwok, M. W.; Kwok, T.; Langford, T. J.; Lau, K.; Lebanowski, L.; Lee, J.; Lei, R. T.; Leitner, R.; Leung, K. Y.; Leung, J. K. C.; Lewis, C. A.; Li, D. J.; Li, F.; Li, G. S.; Li, Q. J.; Li, S. C.; Li, W. D.; Li, X. N.; Li, X. Q.; Li, Y. F.; Li, Z. B.; Liang, H.; Lin, C. J.; Lin, G. L.; Lin, P. Y.; Lin, S. K.; Ling, J. J.; Link, J. M.; Littenberg, L.; Littlejohn, B. R.; Liu, D. W.; Liu, H.; Liu, J. L.; Liu, J. C.; Liu, S. S.; Lu, C.; Lu, H. Q.; Lu, J. S.; Luk, K. B.; Ma, Q. M.; Ma, X. Y.; Ma, X. B.; Ma, Y. Q.; Martinez Caicedo, D. A.; McDonald, K. T.; McKeown, R. D.; Meng, Y.; Mitchell, I.; Monari Kebwaro, J.; Nakajima, Y.; Napolitano, J.; Naumov, D.; Naumova, E.; Ngai, H. Y.; Ning, Z.; Ochoa-Ricoux, J. P.; Olshevski, A.; Pan, H.-R.; Park, J.; Patton, S.; Pec, V.; Peng, J. C.; Piilonen, L. E.; Pinsky, L.; Pun, C. S. J.; Qi, F. Z.; Qi, M.; Qian, X.; Raper, N.; Ren, B.; Ren, J.; Rosero, R.; Roskovec, B.; Ruan, X. C.; Shao, B. B.; Steiner, H.; Sun, G. X.; Sun, J. L.; Tang, W.; Taychenachev, D.; Tsang, K. V.; Tull, C. E.; Tung, Y. C.; Viaux, N.; Viren, B.; Vorobel, V.; Wang, C. H.; Wang, M.; Wang, N. Y.; Wang, R. G.; Wang, W.; Wang, W. W.; Wang, X.; Wang, Y. F.; Wang, Z.; Wang, Z.; Wang, Z. M.; Wei, H. Y.; Wen, L. J.; Whisnant, K.; White, C. G.; Whitehead, L.; Wise, T.; Wong, H. L. H.; Wong, S. C. F.; Worcester, E.; Wu, Q.; Xia, D. M.; Xia, J. K.; Xia, X.; Xing, Z. Z.; Xu, J. Y.; Xu, J. L.; Xu, J.; Xu, Y.; Xue, T.; Yan, J.; Yang, C. G.; Yang, L.; Yang, M. S.; Yang, M. T.; Ye, M.; Yeh, M.; Young, B. L.; Yu, G. Y.; Yu, Z. Y.; Zang, S. L.; Zhan, L.; Zhang, C.; Zhang, H. H.; Zhang, J. W.; Zhang, Q. M.; Zhang, Y. M.; Zhang, Y. X.; Zhang, Y. M.; Zhang, Z. J.; Zhang, Z. Y.; Zhang, Z. P.; Zhao, J.; Zhao, Q. W.; Zhao, Y. F.; Zhao, Y. B.; Zheng, L.; Zhong, W. L.; Zhou, L.; Zhou, N.; Zhuang, H. L.; Zou, J. H.; Daya Bay Collaboration

    2016-02-01

    This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9 GWt h nuclear reactors with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296 721 and 41 589 inverse β decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55 ±0.04 ) ×10-18 cm2 GW-1 day-1 or (5.92 ±0.14 ) ×10-43 cm2 fission-1 . This flux measurement is consistent with previous short-baseline reactor antineutrino experiments and is 0.946 ±0.022 (0.991 ±0.023 ) relative to the flux predicted with the Huber -Mueller (ILL -Vogel ) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2 σ over the full energy range with a local significance of up to ˜4 σ between 4-6 MeV. A reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.

  10. Making sense of absolute measurement: James Clerk Maxwell, William Thomson, Fleeming Jenkin, and the invention of the dimensional formula

    NASA Astrophysics Data System (ADS)

    Mitchell, Daniel Jon

    2017-05-01

    During the 1860s, the Committee on Electrical Standards convened by the British Association for the Advancement of Science (BAAS) attempted to articulate, refine, and realize a system of absolute electrical measurement. I describe how this context led to the invention of the dimensional formula by James Clerk Maxwell and subsequently shaped its interpretation, in particular through the attempts of William Thomson and Fleeming Jenkin to make absolute electrical measurement intelligible to telegraph engineers. I identify unit conversion as the canonical purpose for dimensional formulae during the remainder of the nineteenth century and go on to explain how an operational interpretation was developed by the French physicist Gabriel Lippmann. The focus on the dimensional formula reveals how various conceptual, theoretical, and material aspects of absolute electrical measurement were taken up or resisted in experimental physics, telegraphic engineering, and electrical practice more broadly, which leads to the conclusion that the integration of electrical theory and telegraphic practice was far harder to achieve and maintain than historians have previously thought. This ultimately left a confusing legacy of dimensional concepts and practices in physics.

  11. Absolute gravimetry for monitoring geodynamics in Greenland.

    NASA Astrophysics Data System (ADS)

    Nielsen, E.; Strykowski, G.; Forsberg, R.

    2015-12-01

    Here are presented the preliminary results of the absolute gravity measurements done in Greenland by DTU Space with their A10 absolute gravimeter (the A10-019). The purpose, besides establishing and maintaining a national gravity network, is to study geodynamics.The absolute gravity measurements are juxtaposed with the permanent GNET GNSS stations. The first measurements were conducted in 2009 and a few sites have been re-visited. As of present is there a gravity value at 18 GNET sites.There are challenges in interpreting the measurements from Greenland and several signals has to be taken into account, besides the geodynamical signals originating from the changing load of the ice, there is also a clear signal of direct attraction from different masses. Here are presented the preliminary results of our measurements in Greenland and attempts explain them through modelling of the geodynamical signals and the direct attraction from the ocean and ice.

  12. Measurement of air and VOC vapor fluxes during gas-driven soil remediation: bench-scale experiments.

    PubMed

    Kim, Heonki; Kim, Taeyun; Shin, Seungyeop; Annable, Michael D

    2012-09-04

    In this laboratory study, an experimental method was developed for the quantitative analyses of gas fluxes in soil during advective air flow. One-dimensional column and two- and three-dimensional flow chamber models were used in this study. For the air flux measurement, n-octane vapor was used as a tracer, and it was introduced in the air flow entering the physical models. The tracer (n-octane) in the gas effluent from the models was captured for a finite period of time using a pack of activated carbon, which then was analyzed for the mass of n-octane. The air flux was calculated based on the mass of n-octane captured by the activated carbon and the inflow concentration. The measured air fluxes are in good agreement with the actual values for one- and two-dimensional model experiments. Using both the two- and three-dimensional models, the distribution of the air flux at the soil surface was measured. The distribution of the air flux was found to be affected by the depth of the saturated zone. The flux and flux distribution of a volatile contaminant (perchloroethene) was also measured by using the two-dimensional model. Quantitative information of both air and contaminant flux may be very beneficial for analyzing the performance of gas-driven subsurface remediation processes including soil vapor extraction and air sparging.

  13. Uncertainties Associated with Flux Measurements Due to Heterogeneous Contaminant Distributions

    EPA Science Inventory

    Mass flux and mass discharge measurements at contaminated sites have been applied to assist with remedial management, and can be divided into two broad categories: point-scale measurement techniques and pumping methods. Extrapolation across un-sampled space is necessary when usi...

  14. Absolute marine gravimetry with matter-wave interferometry.

    PubMed

    Bidel, Y; Zahzam, N; Blanchard, C; Bonnin, A; Cadoret, M; Bresson, A; Rouxel, D; Lequentrec-Lalancette, M F

    2018-02-12

    Measuring gravity from an aircraft or a ship is essential in geodesy, geophysics, mineral and hydrocarbon exploration, and navigation. Today, only relative sensors are available for onboard gravimetry. This is a major drawback because of the calibration and drift estimation procedures which lead to important operational constraints. Atom interferometry is a promising technology to obtain onboard absolute gravimeter. But, despite high performances obtained in static condition, no precise measurements were reported in dynamic. Here, we present absolute gravity measurements from a ship with a sensor based on atom interferometry. Despite rough sea conditions, we obtained precision below 10 -5  m s -2 . The atom gravimeter was also compared with a commercial spring gravimeter and showed better performances. This demonstration opens the way to the next generation of inertial sensors (accelerometer, gyroscope) based on atom interferometry which should provide high-precision absolute measurements from a moving platform.

  15. The orbit of Phi Cygni measured with long-baseline optical interferometry - Component masses and absolute magnitudes

    NASA Technical Reports Server (NTRS)

    Armstrong, J. T.; Hummel, C. A.; Quirrenbach, A.; Buscher, D. F.; Mozurkewich, D.; Vivekanand, M.; Simon, R. S.; Denison, C. S.; Johnston, K. J.; Pan, X.-P.

    1992-01-01

    The orbit of the double-lined spectroscopic binary Phi Cygni, the distance to the system, and the masses and absolute magnitudes of its components are presented via measurements with the Mar III Optical Interferometer. On the basis of a reexamination of the spectroscopic data of Rach & Herbig (1961), the values and uncertainties are adopted for the period and the projected semimajor axes from the present fit to the spectroscopic data and the values of the remaining elements from the present fit to the Mark III data. The elements of the true orbit are derived, and the masses and absolute magnitudes of the components, and the distance to the system are calculated.

  16. Absolute calibration of optical flats

    DOEpatents

    Sommargren, Gary E.

    2005-04-05

    The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

  17. Neutrino flux prediction at MiniBooNE

    NASA Astrophysics Data System (ADS)

    Aguilar-Arevalo, A. A.; Anderson, C. E.; Bazarko, A. O.; Brice, S. J.; Brown, B. C.; Bugel, L.; Cao, J.; Coney, L.; Conrad, J. M.; Cox, D. C.; Curioni, A.; Djurcic, Z.; Finley, D. A.; Fleming, B. T.; Ford, R.; Garcia, F. G.; Garvey, G. T.; Green, C.; Green, J. A.; Hart, T. L.; Hawker, E.; Imlay, R.; Johnson, R. A.; Karagiorgi, G.; Kasper, P.; Katori, T.; Kobilarcik, T.; Kourbanis, I.; Koutsoliotas, S.; Laird, E. M.; Linden, S. K.; Link, J. M.; Liu, Y.; Liu, Y.; Louis, W. C.; Mahn, K. B. M.; Marsh, W.; Martin, P. S.; McGregor, G.; Metcalf, W.; Meyers, P. D.; Mills, F.; Mills, G. B.; Monroe, J.; Moore, C. D.; Nelson, R. H.; Nguyen, V. T.; Nienaber, P.; Nowak, J. A.; Ouedraogo, S.; Patterson, R. B.; Perevalov, D.; Polly, C. C.; Prebys, E.; Raaf, J. L.; Ray, H.; Roe, B. P.; Russell, A. D.; Sandberg, V.; Schirato, R.; Schmitz, D.; Shaevitz, M. H.; Shoemaker, F. C.; Smith, D.; Soderberg, M.; Sorel, M.; Spentzouris, P.; Stancu, I.; Stefanski, R. J.; Sung, M.; Tanaka, H. A.; Tayloe, R.; Tzanov, M.; van de Water, R.; Wascko, M. O.; White, D. H.; Wilking, M. J.; Yang, H. J.; Zeller, G. P.; Zimmerman, E. D.

    2009-04-01

    The booster neutrino experiment (MiniBooNE) searches for νμ→νe oscillations using the O(1GeV) neutrino beam produced by the booster synchrotron at the Fermi National Accelerator Laboratory). The booster delivers protons with 8 GeV kinetic energy (8.89GeV/c momentum) to a beryllium target, producing neutrinos from the decay of secondary particles in the beam line. We describe the Monte Carlo simulation methods used to estimate the flux of neutrinos from the beam line incident on the MiniBooNE detector for both polarities of the focusing horn. The simulation uses the Geant4 framework for propagating particles, accounting for electromagnetic processes and hadronic interactions in the beam line materials, as well as the decay of particles. The absolute double differential cross sections of pion and kaon production in the simulation have been tuned to match external measurements, as have the hadronic cross sections for nucleons and pions. The statistical precision of the flux predictions is enhanced through reweighting and resampling techniques. Systematic errors in the flux estimation have been determined by varying parameters within their uncertainties, accounting for correlations where appropriate.

  18. Performance of Different Light Sources for the Absolute Calibration of Radiation Thermometers

    NASA Astrophysics Data System (ADS)

    Martín, M. J.; Mantilla, J. M.; del Campo, D.; Hernanz, M. L.; Pons, A.; Campos, J.

    2017-09-01

    The evolving mise en pratique for the definition of the kelvin (MeP-K) [1, 2] will, in its forthcoming edition, encourage the realization and dissemination of the thermodynamic temperature either directly (primary thermometry) or indirectly (relative primary thermometry) via fixed points with assigned reference thermodynamic temperatures. In the last years, the Centro Español de Metrología (CEM), in collaboration with the Instituto de Óptica of Consejo Superior de Investigaciones Científicas (IO-CSIC), has developed several setups for absolute calibration of standard radiation thermometers using the radiance method to allow CEM the direct dissemination of the thermodynamic temperature and the assignment of the thermodynamic temperatures to several fixed points. Different calibration facilities based on a monochromator and/or a laser and an integrating sphere have been developed to calibrate CEM's standard radiation thermometers (KE-LP2 and KE-LP4) and filter radiometer (FIRA2). This system is based on the one described in [3] placed in IO-CSIC. Different light sources have been tried and tested for measuring absolute spectral radiance responsivity: a Xe-Hg 500 W lamp, a supercontinuum laser NKT SuperK-EXR20 and a diode laser emitting at 6473 nm with a typical maximum power of 120 mW. Their advantages and disadvantages have been studied such as sensitivity to interferences generated by the laser inside the filter, flux stability generated by the radiant sources and so forth. This paper describes the setups used, the uncertainty budgets and the results obtained for the absolute temperatures of Cu, Co-C, Pt-C and Re-C fixed points, measured with the three thermometers with central wavelengths around 650 nm.

  19. Theoretical simulation of the dual-heat-flux method in deep body temperature measurements.

    PubMed

    Huang, Ming; Chen, Wenxi

    2010-01-01

    Deep body temperature reveals individual physiological states, and is important in patient monitoring and chronobiological studies. An innovative dual-heat-flux method has been shown experimentally to be competitive with the conventional zero-heat-flow method in its performance, in terms of measurement accuracy and step response to changes in the deep temperature. We have utilized a finite element method to model and simulate the dynamic process of a dual-heat-flux probe in deep body temperature measurements to validate the fundamental principles of the dual-heat-flux method theoretically, and to acquire a detailed quantitative description of the thermal profile of the dual-heat-flux probe. The simulation results show that the estimated deep body temperature is influenced by the ambient temperature (linearly, at a maximum rate of 0.03 °C/°C) and the blood perfusion rate. The corresponding depth of the estimated temperature in the skin and subcutaneous tissue layer is consistent when using the dual-heat-flux probe. Insights in improving the performance of the dual-heat-flux method were discussed for further studies of dual-heat-flux probes, taking into account structural and geometric considerations.

  20. Comparison of measured and modeled radiation, heat and water vapor fluxes: FIFE pilot study

    NASA Technical Reports Server (NTRS)

    Blad, Blaine L.; Verma, Shashi B.; Hubbard, Kenneth G.; Starks, Patrick; Hays, Cynthia; Norman, John M.; Waltershea, Elizabeth

    1988-01-01

    The primary objectives of the 1985 study were to test the feasibility of using radio frequency receivers to collect data from automated weather stations and to evaluate the use of the data collected by the automated weather stations for modeling the fluxes of latent heat, sensible heat, and radiation over wheat. The model Cupid was used to calculate these fluxes which were compared with fluxes of these entities measured using micrometeorological techniques. The primary objectives of the 1986 study were to measure and model reflected and emitted radiation streams at a few locations within the First International Satellite Land-Surface Climatology Project Field Experiment (FIFE) site and to compare modeled and measured latent heat and sensible heat fluxes from the prairie vegetation.

  1. Imposing strong constraints on tropical terrestrial CO2 fluxes using passenger aircraft based measurements

    NASA Astrophysics Data System (ADS)

    Niwa, Y.; Machida, T.; Sawa, Y.; Matsueda, H.; Schuck, T. J.; Brenninkmeijer, C. A.; Imasu, R.; Satoh, M.

    2011-12-01

    Better understanding of the global and regional carbon budget is needed to perform a reliable prediction of future climate with an earth system model. However, the reliability of CO2 source/sink estimation by inverse modeling, which is one of the promising methods to estimate regional carbon budget, is limited because of sparse observational data coverage. Very few observational data are available in tropics. Therefore, especially the reconstruction of tropical terrestrial fluxes has considerable uncertainties. In this study, regional CO2 fluxes for 2006-2008 are estimated by inverse modeling using the Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) in addition to the surface measurement dataset of GLOBALVIEW-CO2. CONTRAIL is a recently established CO2 measurement network using in-situ measurement instruments on board commercial aircraft. Five CONTRAIL aircraft travel back and forth between Japan and many areas: Europe, North America, Southeast Asia, South Asia, and Australia. The Bayesian synthesis approach is used to estimate monthly fluxes for 42 regions using NICAM-TM simulations with existing CO2 flux datasets and monthly mean observational data. It is demonstrated that the aircraft data have great impact on estimated tropical terrestrial fluxes. By adding the aircraft data to the surface data, the analyzed uncertainty of tropical fluxes has been reduced by 15 % and more than 30 % uncertainty reduction rate is found in Southeast and South Asia. Specifically, for annual net CO2 fluxes, nearly neutral fluxes of Indonesia, which is estimated using the surface dataset alone, turn to positive fluxes, i.e. carbon sources. In Indonesia, a remarkable carbon release during the severe drought period of October-December in 2006 is estimated, which suggests that biosphere respiration or biomass burning was larger than the prior fluxes. Comparison of the optimized atmospheric CO2 with independent aircraft measurements of CARIBIC tends to validate

  2. Development of airborne eddy-correlation flux measurement capabilities for reactive oxides of nitrogen

    NASA Technical Reports Server (NTRS)

    Bradshaw, John (Principal Investigator); Zheng, Xiaonan; Sandholm, Scott T.

    1996-01-01

    This research is aimed at producing a fundamental new research tool for characterizing the source strength of the most important compound controlling the hemispheric and global scale distribution of tropospheric ozone. Specifically, this effort seeks to demonstrate the proof-of-concept of a new general purpose laser-induced fluorescence based spectrometer for making airborne eddy-correlation flux measurements of nitric oxide (NO) and other reactive nitrogen compounds. The new all solid-state laser technology being used in this advanced sensor will produce a forerunner of the type of sensor technology that should eventually result in highly compact operational systems. The proof-of-concept sensor being developed will have over two orders-of-magnitude greater sensitivity than present-day instruments. In addition, this sensor will offer the possibility of eventual extension to airborne eddy-correlation flux measurements of nitrogen dioxide (NO2) and possibly other compounds, such as ammonia (NH3), peroxyradicals (HO2), nitrateradicals (NO3) and several iodine compounds (e.g., I and IO). Demonstration of the new sensor's ability to measure NO fluxes will occur through a series of laboratory and field tests. This proof-of-concept demonstration will show that not only can airborne fluxes of important ultra-trace compounds be made at the few parts-per-trillion level, but that the high accuracy/precision measurements currently needed for predictive models can also. These measurement capabilities will greatly enhance our current ability to quantify the fluxes of reactive nitrogen into the troposphere and significantly impact upon the accuracy of predictive capabilities to model O3's distribution within the remote troposphere. This development effort also offers a timely approach for producing the reactive nitrogen flux measurement capabilities that will be needed by future research programs such as NASA's planned 1999 Amazon Biogeochemistry and Atmospheric Chemistry

  3. Linking Comparisons of Absolute Gravimeters: A Proof of Concept for a new Global Absolute Gravity Reference System.

    NASA Astrophysics Data System (ADS)

    Wziontek, H.; Palinkas, V.; Falk, R.; Vaľko, M.

    2016-12-01

    Since decades, absolute gravimeters are compared on a regular basis on an international level, starting at the International Bureau for Weights and Measures (BIPM) in 1981. Usually, these comparisons are based on constant reference values deduced from all accepted measurements acquired during the comparison period. Temporal changes between comparison epochs are usually not considered. Resolution No. 2, adopted by IAG during the IUGG General Assembly in Prague 2015, initiates the establishment of a Global Absolute Gravity Reference System based on key comparisons of absolute gravimeters (AG) under the International Committee for Weights and Measures (CIPM) in order to establish a common level in the microGal range. A stable and unique reference frame can only be achieved, if different AG are taking part in different kind of comparisons. Systematic deviations between the respective comparison reference values can be detected, if the AG can be considered stable over time. The continuous operation of superconducting gravimeters (SG) on selected stations further supports the temporal link of comparison reference values by establishing a reference function over time. By a homogenous reprocessing of different comparison epochs and including AG and SG time series at selected stations, links between several comparisons will be established and temporal comparison reference functions will be derived. By this, comparisons on a regional level can be traced to back to the level of key comparisons, providing a reference for other absolute gravimeters. It will be proved and discussed, how such a concept can be used to support the future absolute gravity reference system.

  4. Optimizing laboratory-based radon flux measurements for sediments.

    PubMed

    Chanyotha, Supitcha; Kranrod, Chutima; Kritsananuwat, Rawiwan; Lane-Smith, Derek; Burnett, William C

    2016-07-01

    Radon flux via diffusion from sediments and other materials may be determined in the laboratory by circulating air through the sample and a radon detector in a closed loop. However, this approach is complicated by the necessity of having to determine the total air volume in the system and accounting for any small air leaks that can arise if using extended measurement periods. We designed a simple open-loop configuration that includes a measured mass of wet sediment and water inside a gas-tight reaction flask connected to a drying system and a radon-in-air analyzer. Ambient air flows through two charcoal columns before entering the reaction vessel to eliminate incoming radon. After traveling through the reaction flask, the air passes the drier and the radon analyzer and is then vented. After some time, the radon activity will reach a steady state depending upon the airflow rate. With this approach, the radon flux via diffusion is simply the product of the steady-state radon activity (Bq/m(3)) multiplied by the airflow rate (mL/min). We demonstrated that this setup could produce good results for materials that produce relatively high radon fluxes. We also show that a modified closed system approach, including radon removal of the incoming air by charcoal filtration in a bypass, can produce very good results including samples with very low emission rates. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Absolute optical extinction measurements of single nano-objects by spatial modulation spectroscopy using a white lamp

    NASA Astrophysics Data System (ADS)

    Billaud, Pierre; Marhaba, Salem; Grillet, Nadia; Cottancin, Emmanuel; Bonnet, Christophe; Lermé, Jean; Vialle, Jean-Louis; Broyer, Michel; Pellarin, Michel

    2010-04-01

    This article describes a high sensitivity spectrophotometer designed to detect the overall extinction of light by a single nanoparticle (NP) in the 10-4-10-5 relative range, using a transmission measurement configuration. We focus here on the simple and low cost scheme where a white lamp is used as a light source, permitting easy and broadband extinction measurements (300-900 nm). Using a microscope, in a confocal geometry, an increased sensitivity is reached thanks to a modulation of the NP position under the light spot combined with lock-in detection. Moreover, it is shown that this technique gives access to the absolute extinction cross-sections of the single NP provided that the incident electromagnetic field distribution experienced by the NP is accurately characterized. In this respect, an experimental procedure to characterize the light spot profile in the focal plane, using a reference NP as a probe, is also laid out. The validity of this approach is discussed and confirmed by comparing experimental intensity distributions to theoretical calculations taking into account the vector character of the tightly focused beam. The calibration procedure permitting to obtain the absolute extinction cross-section of the probed NP is then fully described. Finally, the force of the present technique is illustrated through selected examples concerning spherical and slightly elongated gold and silver NPs. Absolute extinction measurements are found to be in good consistency with the NP size and shape independently obtained from transmission electron microscopy, showing that spatial modulation spectroscopy is a powerful tool to get an optical fingerprint of the NP.

  6. Temporal variation of VOC fluxes measured with PTR-TOF above a boreal forest

    NASA Astrophysics Data System (ADS)

    Schallhart, Simon; Rantala, Pekka; Kajos, Maija K.; Aalto, Juho; Mammarella, Ivan; Ruuskanen, Taina M.; Kulmala, Markku

    2018-01-01

    Between April and June 2013 fluxes of volatile organic compounds (VOCs) were measured in a Scots pine and Norway spruce forest using the eddy covariance (EC) method with a proton transfer reaction time-of-flight (PTR-TOF) mass spectrometer. The observations were performed above a boreal forest at the SMEAR II site in southern Finland.We found a total of 25 different compounds with exchange and investigated their seasonal variations from spring to summer. The majority of the net VOC flux was comprised of methanol, monoterpenes, acetone and butene + butanol. The butene + butanol emissions were concluded to not originate from the forest and, therefore, be anthropogenic. The VOC exchange followed a seasonal trend and the emissions increased from spring to summer. Only three compounds were emitted during the snowmelt while in summer emissions of some 19 VOCs were observed. During the measurement period in April, the emissions were dominated by butene + butanol, while during the start of the growing season and in summer, methanol was the most emitted compound. The main source of methanol was likely the growth of new biomass. During a 21-day period in June, the net VOC flux was 2.1 nmol m-2 s-1. This is on the lower end of PTR-TOF flux measurements from other ecosystems, which range from 2 to 10 nmol m-2 s-1. The EC flux results were compared with surface layer profile measurements, using a proton transfer reaction quadrupole mass spectrometer, which is permanently installed at the SMEAR II site. For the major compounds, the fluxes measured with the two different methods agreed well.

  7. Far-ultraviolet spectra and flux distributions of some Orion stars

    NASA Technical Reports Server (NTRS)

    Carruthers, G. R.; Heckathorn, H. M.; Opal, C. B.

    1981-01-01

    Far-ultraviolet (950-1800 A) spectra with about 2 A resolution were obtained of a number of stars in Orion during a sounding-rocket flight 1975 December 6. These spectra have been reduced to absolute flux distributions with the aid of preflight calibrations. The derived fluxes are in good agreement with model-atmosphere predictions and previous observations down to about 1200 A. In the 1200-1080 A range, the present results are in good agreement with model predictions but fall above the rocket measurements of Brune, Mount and Feldman. Below 1080 A, our measurements fall below the model predictions, reaching a deviation of a factor of 2 near 1010 A and a factor of 4 near 950 A. The present results are compared with those of Brune et al. via Copernicus U2 observations in this spectral range, and possible sources of discrepancies between the various observations and model-atmosphere predictions are discussed. Other aspects of the spectra, particularly with regard to spectral classification, are briefly discussed.

  8. Measured and calculated fast neutron spectra in a depleted uranium and lithium hydride shielded reactor

    NASA Technical Reports Server (NTRS)

    Lahti, G. P.; Mueller, R. A.

    1973-01-01

    Measurements of MeV neutron were made at the surface of a lithium hydride and depleted uranium shielded reactor. Four shield configurations were considered: these were assembled progressively with cylindrical shells of 5-centimeter-thick depleted uranium, 13-centimeter-thick lithium hydride, 5-centimeter-thick depleted uranium, 13-centimeter-thick lithium hydride, 5-centimeter-thick depleted uranium, and 3-centimeter-thick depleted uranium. Measurements were made with a NE-218 scintillation spectrometer; proton pulse height distributions were differentiated to obtain neutron spectra. Calculations were made using the two-dimensional discrete ordinates code DOT and ENDF/B (version 3) cross sections. Good agreement between measured and calculated spectral shape was observed. Absolute measured and calculated fluxes were within 50 percent of one another; observed discrepancies in absolute flux may be due to cross section errors.

  9. Measurement of the reactor antineutrino flux and spectrum at Daya Bay

    DOE PAGES

    D. E. Jaffe; Bishai, M; Diwan, M.; ...

    2016-02-12

    This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9~GW th nuclear reactors with six detectors deployed in two near (effective baselines 512~m and 561~m) and one far (1,579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296,721 and 41,589 inverse beta decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55 ± 0.04) × 10 –18 cm 2/GW/day or (5.92 ± 0.14) × 10 –43 cm 2/fission. This flux measurement is consistent with previous short-baseline reactor antineutrino experimentsmore » and is 0.946 ± 0.022 (0.991 ± 0.023) relative to the flux predicted with the Huber+Mueller (ILL+Vogel) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2σ over the full energy range with a local significance of up to ~4σ between 4-6 MeV. Furthermore, a reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.« less

  10. Gradient flux measurements of sea-air DMS transfer during the Surface Ocean Aerosol Production (SOAP) experiment

    NASA Astrophysics Data System (ADS)

    Smith, Murray J.; Walker, Carolyn F.; Bell, Thomas G.; Harvey, Mike J.; Saltzman, Eric S.; Law, Cliff S.

    2018-04-01

    Direct measurements of marine dimethylsulfide (DMS) fluxes are sparse, particularly in the Southern Ocean. The Surface Ocean Aerosol Production (SOAP) voyage in February-March 2012 examined the distribution and flux of DMS in a biologically active frontal system in the southwest Pacific Ocean. Three distinct phytoplankton blooms were studied with oceanic DMS concentrations as high as 25 nmol L-1. Measurements of DMS fluxes were made using two independent methods: the eddy covariance (EC) technique using atmospheric pressure chemical ionization-mass spectrometry (API-CIMS) and the gradient flux (GF) technique from an autonomous catamaran platform. Catamaran flux measurements are relatively unaffected by airflow distortion and are made close to the water surface, where gas gradients are largest. Flux measurements were complemented by near-surface hydrographic measurements to elucidate physical factors influencing DMS emission. Individual DMS fluxes derived by EC showed significant scatter and, at times, consistent departures from the Coupled Ocean-Atmosphere Response Experiment gas transfer algorithm (COAREG). A direct comparison between the two flux methods was carried out to separate instrumental effects from environmental effects and showed good agreement with a regression slope of 0.96 (r2 = 0.89). A period of abnormal downward atmospheric heat flux enhanced near-surface ocean stratification and reduced turbulent exchange, during which GF and EC transfer velocities showed good agreement but modelled COAREG values were significantly higher. The transfer velocity derived from near-surface ocean turbulence measurements on a spar buoy compared well with the COAREG model in general but showed less variation. This first direct comparison between EC and GF fluxes of DMS provides confidence in compilation of flux estimates from both techniques, as well as in the stable periods when the observations are not well predicted by the COAREG model.

  11. Infrared Camera Diagnostic for Heat Flux Measurements on NSTX

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    D. Mastrovito; R. Maingi; H.W. Kugel

    2003-03-25

    An infrared imaging system has been installed on NSTX (National Spherical Torus Experiment) at the Princeton Plasma Physics Laboratory to measure the surface temperatures on the lower divertor and center stack. The imaging system is based on an Indigo Alpha 160 x 128 microbolometer camera with 12 bits/pixel operating in the 7-13 {micro}m range with a 30 Hz frame rate and a dynamic temperature range of 0-700 degrees C. From these data and knowledge of graphite thermal properties, the heat flux is derived with a classic one-dimensional conduction model. Preliminary results of heat flux scaling are reported.

  12. Double-cavity radiometer for high-flux density solar radiation measurements.

    PubMed

    Parretta, A; Antonini, A; Armani, M; Nenna, G; Flaminio, G; Pellegrino, M

    2007-04-20

    A radiometric method has been developed, suitable for both total power and flux density profile measurement of concentrated solar radiation. The high-flux density radiation is collected by a first optical cavity, integrated, and driven to a second optical cavity, where, attenuated, it is measured by a conventional radiometer operating under a stationary irradiation regime. The attenuation factor is regulated by properly selecting the aperture areas in the two cavities. The radiometer has been calibrated by a pulsed solar simulator at concentration levels of hundreds of suns. An optical model and a ray-tracing study have also been developed and validated, by which the potentialities of the radiometer have been largely explored.

  13. Progress in obtaining an absolute calibration of a total deuterium-tritium neutron yield diagnostic based on copper activationa)

    NASA Astrophysics Data System (ADS)

    Ruiz, C. L.; Chandler, G. A.; Cooper, G. W.; Fehl, D. L.; Hahn, K. D.; Leeper, R. J.; McWatters, B. R.; Nelson, A. J.; Smelser, R. M.; Snow, C. S.; Torres, J. A.

    2012-10-01

    The 350-keV Cockroft-Walton accelerator at Sandia National laboratory's Ion Beam facility is being used to calibrate absolutely a total DT neutron yield diagnostic based on the 63Cu(n,2n)62Cu(β+) reaction. These investigations have led to first-order uncertainties approaching 5% or better. The experiments employ the associated-particle technique. Deuterons at 175 keV impinge a 2.6 μm thick erbium tritide target producing 14.1 MeV neutrons from the T(d,n)4He reaction. The alpha particles emitted are measured at two angles relative to the beam direction and used to infer the neutron flux on a copper sample. The induced 62Cu activity is then measured and related to the neutron flux. This method is known as the F-factor technique. Description of the associated-particle method, copper sample geometries employed, and the present estimates of the uncertainties to the F-factor obtained are given.

  14. Progress in obtaining an absolute calibration of a total deuterium-tritium neutron yield diagnostic based on copper activation.

    PubMed

    Ruiz, C L; Chandler, G A; Cooper, G W; Fehl, D L; Hahn, K D; Leeper, R J; McWatters, B R; Nelson, A J; Smelser, R M; Snow, C S; Torres, J A

    2012-10-01

    The 350-keV Cockroft-Walton accelerator at Sandia National laboratory's Ion Beam facility is being used to calibrate absolutely a total DT neutron yield diagnostic based on the (63)Cu(n,2n)(62)Cu(β+) reaction. These investigations have led to first-order uncertainties approaching 5% or better. The experiments employ the associated-particle technique. Deuterons at 175 keV impinge a 2.6 μm thick erbium tritide target producing 14.1 MeV neutrons from the T(d,n)(4)He reaction. The alpha particles emitted are measured at two angles relative to the beam direction and used to infer the neutron flux on a copper sample. The induced (62)Cu activity is then measured and related to the neutron flux. This method is known as the F-factor technique. Description of the associated-particle method, copper sample geometries employed, and the present estimates of the uncertainties to the F-factor obtained are given.

  15. Evaluation of Density Corrections to Methane Fluxes Measured by Open-Path Eddy Covariance over Contrasting Landscapes

    NASA Astrophysics Data System (ADS)

    Chamberlain, Samuel D.; Verfaillie, Joseph; Eichelmann, Elke; Hemes, Kyle S.; Baldocchi, Dennis D.

    2017-11-01

    Corrections accounting for air density fluctuations due to heat and water vapour fluxes must be applied to the measurement of eddy-covariance fluxes when using open-path sensors. Experimental tests and ecosystem observations have demonstrated the important role density corrections play in accurately quantifying carbon dioxide (CO2) fluxes, but less attention has been paid to evaluating these corrections for methane (CH4) fluxes. We measured CH4 fluxes with open-path sensors over a suite of sites with contrasting CH4 emissions and energy partitioning, including a pavement airfield, two negligible-flux ecosystems (drained alfalfa and pasture), and two high-flux ecosystems (flooded wetland and rice). We found that density corrections successfully re-zeroed fluxes in negligible-flux sites; however, slight overcorrection was observed above pavement. The primary impact of density corrections varied over negligible- and high-flux ecosystems. For negligible-flux sites, corrections led to greater than 100% adjustment in daily budgets, while these adjustments were only 3-10% in high-flux ecosystems. The primary impact to high-flux ecosystems was a change in flux diel patterns, which may affect the evaluation of relationships between biophysical drivers and fluxes if correction bias exists. Additionally, accounting for density effects to high-frequency CH4 fluctuations led to large differences in observed CH4 flux cospectra above negligible-flux sites, demonstrating that similar adjustments should be made before interpreting CH4 cospectra for comparable ecosystems. These results give us confidence in CH4 fluxes measured by open-path sensors, and demonstrate that density corrections play an important role in adjusting flux budgets and diel patterns across a range of ecosystems.

  16. Airflows and turbulent flux measurements in mountainous terrain: Part 1. Canopy and local effects

    USGS Publications Warehouse

    Turnipseed, Andrew A.; Anderson, Dean E.; Blanken, Peter D.; Baugh, William M.; Monson, Russell K.

    2003-01-01

    We have studied the effects of local topography and canopy structure on turbulent flux measurements at a site located in mountainous terrain within a subalpine, coniferous forest. Our primary aim was to determine whether the complex terrain of the site affects the accuracy of eddy flux measurements from a practical perspective. We observed displacement heights, roughness lengths, spectral peaks, turbulent length scales, and profiles of turbulent intensities that were comparable in magnitude and pattern to those reported for forest canopies in simpler terrain. We conclude that in many of these statistical measures, the local canopy exerts considerably more influence than does topographical complexity. Lack of vertical flux divergence and modeling suggests that the flux footprints for the site are within the standards acceptable for the application of flux statistics. We investigated three different methods of coordinate rotation: double rotation (DR), triple rotation (TR), and planar-fit rotation (PF). Significant variability in rotation angles at low wind speeds was encountered with the commonly used DR and TR methods, as opposed to the PF method, causing some overestimation of the fluxes. However, these differences in fluxes were small when applied to large datasets involving sensible heat and CO2 fluxes. We observed evidence of frequent drainage flows near the ground during stable, stratified conditions at night. Concurrent with the appearance of these flows, we observed a positive bias in the mean vertical wind speed, presumably due to subtle topographic variations inducing a flow convergence below the measurement sensors. In the presence of such drainage flows, advection of scalars and non-zero bias in the mean vertical wind speed can complicate closure of the mass conservation budget at the site.

  17. Can CO2 Turbulent Flux Be Measured by Lidar? A Preliminary Study

    NASA Technical Reports Server (NTRS)

    Gilbert, Fabien; Koch, Grady; Beyon, Jeffrey Y.; Hilton, Timothy W.; Davis, Kenneth J.; Andrews, Arlyn; Flamant, Pierre H.; Singh, Upendra N.

    2011-01-01

    The vertical profiling ofCO2 turbulent fluxes in the atmospheric boundary layer (ABL) is investigated using a coherent differential absorption lidar (CDIAL) operated nearby a tall tower in Wisconsin during June 2007. A CDIAL can perform simultaneous range-resolved CO2 DIAL and velocity measurements. The lidar eddy covariance technique is presented. The aims of the study are (i) an assessment of performance and current limitation of available CDIAL for CO2 turbulent fluxes and (ii) the derivation of instrument specifications to build a future CDIAL to perform accurate range-resolved CO2 fluxes. Experimental lidar CO2 mixing ratio and vertical velocity profiles are successfully compared with in situ sensors measurements. Time and space integral scales of turbulence in the ABL are addressed that result in limitation for time averaging and range accumulation. A first attempt to infer CO2 fluxes using an eddy covariance technique with currently available 2-mm CDIAL dataset is reported.

  18. Evaluation of Heat Flux Measurement as a New Process Analytical Technology Monitoring Tool in Freeze Drying.

    PubMed

    Vollrath, Ilona; Pauli, Victoria; Friess, Wolfgang; Freitag, Angelika; Hawe, Andrea; Winter, Gerhard

    2017-05-01

    This study investigates the suitability of heat flux measurement as a new technique for monitoring product temperature and critical end points during freeze drying. The heat flux sensor is tightly mounted on the shelf and measures non-invasively (no contact with the product) the heat transferred from shelf to vial. Heat flux data were compared to comparative pressure measurement, thermocouple readings, and Karl Fischer titration as current state of the art monitoring techniques. The whole freeze drying process including freezing (both by ramp freezing and controlled nucleation) and primary and secondary drying was considered. We found that direct measurement of the transferred heat enables more insights into thermodynamics of the freezing process. Furthermore, a vial heat transfer coefficient can be calculated from heat flux data, which ultimately provides a non-invasive method to monitor product temperature throughout primary drying. The end point of primary drying determined by heat flux measurements was in accordance with the one defined by thermocouples. During secondary drying, heat flux measurements could not indicate the progress of drying as monitoring the residual moisture content. In conclusion, heat flux measurements are a promising new non-invasive tool for lyophilization process monitoring and development using energy transfer as a control parameter. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  19. Absolute Bunch Length Measurements at the ALS by Incoherent Synchrotron Radiation Fluctuation Analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Filippetto, D.; /Frascati; Sannibale, F.

    2008-01-24

    By analyzing the pulse to pulse intensity fluctuations of the radiation emitted by a charge particle in the incoherent part of the spectrum, it is possible to extract information about the spatial distribution of the beam. At the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory, we have developed and tested a simple scheme based on this principle that allows for the absolute measurement of the bunch length. A description of the method and the experimental results are presented.

  20. Evaluation of absolute measurement using a 4π plastic scintillator for the 4πβ-γ coincidence counting method.

    PubMed

    Unno, Y; Sanami, T; Sasaki, S; Hagiwara, M; Yunoki, A

    2018-04-01

    Absolute measurement by the 4πβ-γ coincidence counting method was conducted by two photomultipliers facing across a plastic scintillator to be focused on β ray counting efficiency. The detector was held with a through-hole-type NaI(Tl) detector. The results include absolutely determined activity and its uncertainty especially about extrapolation. A comparison between the obtained and known activities showed agreement within their uncertainties. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Tunneling of Massive Flux Lines in a High Tc Superconductor at absolute Zero

    NASA Astrophysics Data System (ADS)

    Narahari Achar, B. N.; Waleed Gaber, M.

    1997-11-01

    Our previous study(M. W. Gaber and B. N. N. Achar, Phys. Rev. B52, 1314(1995)) of quantum tunneling of damped flux lines of finite mass has been extended over the temperature range from the crossover temperature T0 to T=0 with a view to investigate further the temperature dependence of the tunneling rate found earlier. It has been found that at T=0, for the case of the cubic pinning potential, the action can be evaluated in a closed form for a flux line of finite length. The only non-zero contribution arises from the dissipation term resulting in a finite action.

  2. High-resolution hot-film measurement of surface heat flux to an impinging jet

    NASA Astrophysics Data System (ADS)

    O'Donovan, T. S.; Persoons, T.; Murray, D. B.

    2011-10-01

    To investigate the complex coupling between surface heat transfer and local fluid velocity in convective heat transfer, advanced techniques are required to measure the surface heat flux at high spatial and temporal resolution. Several established flow velocity techniques such as laser Doppler anemometry, particle image velocimetry and hot wire anemometry can measure fluid velocities at high spatial resolution (µm) and have a high-frequency response (up to 100 kHz) characteristic. Equivalent advanced surface heat transfer measurement techniques, however, are not available; even the latest advances in high speed thermal imaging do not offer equivalent data capture rates. The current research presents a method of measuring point surface heat flux with a hot film that is flush mounted on a heated flat surface. The film works in conjunction with a constant temperature anemometer which has a bandwidth of 100 kHz. The bandwidth of this technique therefore is likely to be in excess of more established surface heat flux measurement techniques. Although the frequency response of the sensor is not reported here, it is expected to be significantly less than 100 kHz due to its physical size and capacitance. To demonstrate the efficacy of the technique, a cooling impinging air jet is directed at the heated surface, and the power required to maintain the hot-film temperature is related to the local heat flux to the fluid air flow. The technique is validated experimentally using a more established surface heat flux measurement technique. The thermal performance of the sensor is also investigated numerically. It has been shown that, with some limitations, the measurement technique accurately measures the surface heat transfer to an impinging air jet with improved spatial resolution for a wide range of experimental parameters.

  3. A high-resolution optical measurement system for rapid acquisition of radiation flux density maps

    NASA Astrophysics Data System (ADS)

    Thelen, Martin; Raeder, Christian; Willsch, Christian; Dibowski, Gerd

    2017-06-01

    To identify the power and flux density of concentrated solar radiation the Institute of Solar Research at the German Aerospace Center (DLR - Deutsches Zentrum für Luft-und Raumfahrt e. V.) has used the camera-based measurement system FATMES (Flux and Temperature Measurement System) since 1995. The disadvantages of low resolution, difficult handling and poor computing power required a revision of the existing measurement system. The measurement system FMAS (Flux Mapping Acquisition system) is equipped with state-of-the-art-hardware, is compatible with computers off-the-shelf and is programmed in LabView. The expenditure of time for an image evaluation is reduced by the factor 60 compared to FATMES. The new measurement system is no longer associated with the facilities Solar Furnace and High Flux Solar Simulator at the DLR in Cologne but is also applicable as a mobile system. The data and the algorithms are transparent throughout the complete process. The measurement accuracy of FMAS is determined to at most ±3 % until now. The error of measurement of FATMES is at least 2 % higher according to the conducted comparison tests.

  4. Absolute frequency measurement of the ? optical clock transition in ? with an uncertainty of ? using a frequency link to international atomic time

    NASA Astrophysics Data System (ADS)

    Baynham, Charles F. A.; Godun, Rachel M.; Jones, Jonathan M.; King, Steven A.; Nisbet-Jones, Peter B. R.; Baynes, Fred; Rolland, Antoine; Baird, Patrick E. G.; Bongs, Kai; Gill, Patrick; Margolis, Helen S.

    2018-03-01

    The highly forbidden ? electric octupole transition in ? is a potential candidate for a redefinition of the SI second. We present a measurement of the absolute frequency of this optical transition, performed using a frequency link to International Atomic Time to provide traceability to the SI second. The ? optical frequency standard was operated for 76% of a 25-day period, with the absolute frequency measured to be 642 121 496 772 645.14(26) Hz. The fractional uncertainty of ? is comparable to that of the best previously reported measurement, which was made by a direct comparison to local caesium primary frequency standards.

  5. Improved absolute calibration of LOPES measurements and its impact on the comparison with REAS 3.11 and CoREAS simulations

    NASA Astrophysics Data System (ADS)

    Apel, W. D.; Arteaga-Velázquez, J. C.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hiller, R.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.; Nehls, S.; Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schoo, S.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.

    2016-02-01

    LOPES was a digital antenna array detecting the radio emission of cosmic-ray air showers. The calibration of the absolute amplitude scale of the measurements was done using an external, commercial reference source, which emits a frequency comb with defined amplitudes. Recently, we obtained improved reference values by the manufacturer of the reference source, which significantly changed the absolute calibration of LOPES. We reanalyzed previously published LOPES measurements, studying the impact of the changed calibration. The main effect is an overall decrease of the LOPES amplitude scale by a factor of 2.6 ± 0.2, affecting all previously published values for measurements of the electric-field strength. This results in a major change in the conclusion of the paper 'Comparing LOPES measurements of air-shower radio emission with REAS 3.11 and CoREAS simulations' published by Apel et al. (2013) : With the revised calibration, LOPES measurements now are compatible with CoREAS simulations, but in tension with REAS 3.11 simulations. Since CoREAS is the latest version of the simulation code incorporating the current state of knowledge on the radio emission of air showers, this new result indicates that the absolute amplitude prediction of current simulations now is in agreement with experimental data.

  6. Absolute measurements of the electronic transition moments of seven band systems of the C2 molecule. Ph.D. Thesis - York Univ., Toronto

    NASA Technical Reports Server (NTRS)

    Cooper, D. M.

    1979-01-01

    Electronic transition moments of seven C2 singlet and triplet band systems in the 0.2-1.2 micron spectral region were measured. The measurements were made in emission behind incident shock waves in C2H2-argon mixtures. Narrow bandpass radiometers were used to obtain absolute measurements of shock-excited C2 radiation from which absolute electronic transition moments are derived by a synthetic spectrum analysis. New results are reported for the Ballik-Ramsay, Phillips, Swan, Deslandres-d'Azambuja, Fox-Herzberg, Mulliken, and Freymark systems.

  7. Planck intermediate results. LII. Planet flux densities

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Akrami, Y.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S.; Benabed, K.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Carron, J.; Chiang, H. C.; Colombo, L. P. L.; Comis, B.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Di Valentino, E.; Dickinson, C.; Diego, J. M.; Doré, O.; Ducout, A.; Dupac, X.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Fantaye, Y.; Finelli, F.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frolov, A.; Galeotta, S.; Galli, S.; Ganga, K.; Génova-Santos, R. T.; Gerbino, M.; González-Nuevo, J.; Górski, K. M.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Helou, G.; Henrot-Versillé, S.; Herranz, D.; Hivon, E.; Jaffe, A. H.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kiiveri, K.; Kim, J.; Kisner, T. S.; Krachmalnicoff, N.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Le Jeune, M.; Lellouch, E.; Levrier, F.; Liguori, M.; Lilje, P. B.; Lindholm, V.; López-Caniego, M.; Ma, Y.-Z.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Maris, M.; Martin, P. G.; Martínez-González, E.; Matarrese, S.; Mauri, N.; McEwen, J. D.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Molinari, D.; Moneti, A.; Montier, L.; Moreno, R.; Morgante, G.; Natoli, P.; Oxborrow, C. A.; Paoletti, D.; Partridge, B.; Patanchon, G.; Patrizii, L.; Perdereau, O.; Piacentini, F.; Plaszczynski, S.; Polenta, G.; Rachen, J. P.; Racine, B.; Reinecke, M.; Remazeilles, M.; Renzi, A.; Rocha, G.; Romelli, E.; Rosset, C.; Roudier, G.; Rubiño-Martín, J. A.; Ruiz-Granados, B.; Salvati, L.; Sandri, M.; Savelainen, M.; Scott, D.; Sirri, G.; Spencer, L. D.; Suur-Uski, A.-S.; Tauber, J. A.; Tavagnacco, D.; Tenti, M.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Trombetti, T.; Valiviita, J.; Van Tent, F.; Vielva, P.; Villa, F.; Wehus, I. K.; Zacchei, A.

    2017-11-01

    Measurements of flux density are described for five planets, Mars, Jupiter, Saturn, Uranus, and Neptune, across the six Planck High Frequency Instrument frequency bands (100-857 GHz) and these are then compared with models and existing data. In our analysis, we have also included estimates of the brightness of Jupiter and Saturn at the three frequencies of the Planck Low Frequency Instrument (30, 44, and 70 GHz). The results provide constraints on the intrinsic brightness and the brightness time-variability of these planets. The majority of the planet flux density estimates are limited by systematic errors, but still yield better than 1% measurements in many cases. Applying data from Planck HFI, the Wilkinson Microwave Anisotropy Probe (WMAP), and the Atacama Cosmology Telescope (ACT) to a model that incorporates contributions from Saturn's rings to the planet's total flux density suggests a best fit value for the spectral index of Saturn's ring system of βring = 2.30 ± 0.03 over the 30-1000 GHz frequency range. Estimates of the polarization amplitude of the planets have also been made in the four bands that have polarization-sensitive detectors (100-353 GHz); this analysis provides a 95% confidence level upper limit on Mars's polarization of 1.8, 1.7, 1.2, and 1.7% at 100, 143, 217, and 353 GHz, respectively. The average ratio between the Planck-HFI measurements and the adopted model predictions for all five planets (excluding Jupiter observations for 353 GHz) is 1.004, 1.002, 1.021, and 1.033 for 100, 143, 217, and 353 GHz, respectively. Model predictions for planet thermodynamic temperatures are therefore consistent with the absolute calibration of Planck-HFI detectors at about the three-percent level. We compare our measurements with published results from recent cosmic microwave background experiments. In particular, we observe that the flux densities measured by Planck HFI and WMAP agree to within 2%. These results allow experiments operating in the mm

  8. High-accuracy determination of the neutron flux in the new experimental area n_TOF-EAR2 at CERN

    NASA Astrophysics Data System (ADS)

    Sabaté-Gilarte, M.; Barbagallo, M.; Colonna, N.; Gunsing, F.; Žugec, P.; Vlachoudis, V.; Chen, Y. H.; Stamatopoulos, A.; Lerendegui-Marco, J.; Cortés-Giraldo, M. A.; Villacorta, A.; Guerrero, C.; Damone, L.; Audouin, L.; Berthoumieux, E.; Cosentino, L.; Diakaki, M.; Finocchiaro, P.; Musumarra, A.; Papaevangelou, T.; Piscopo, M.; Tassan-Got, L.; Aberle, O.; Andrzejewski, J.; Bécares, V.; Bacak, M.; Baccomi, R.; Balibrea, J.; Barros, S.; Bečvář, F.; Beinrucker, C.; Belloni, F.; Billowes, J.; Bosnar, D.; Brugger, M.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chiaveri, E.; Cortés, G.; Deo, K.; Domingo-Pardo, C.; Dressler, R.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Frost, R. J. W.; Furman, V.; Göbel, K.; García, A. R.; Gawlik, A.; Gheorghe, I.; Glodariu, T.; Gonçalves, I. F.; González, E.; Goverdovski, A.; Griesmayer, E.; Harada, H.; Heftrich, T.; Heinitz, S.; Hernández-Prieto, A.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Katabuchi, T.; Kavrigin, P.; Ketlerov, V.; Khryachkov, V.; Kimura, A.; Kivel, N.; Kokkoris, M.; Krtička, M.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Licata, M.; Lo Meo, S.; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Matteucci, F.; Maugeri, E. A.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Nolte, R.; Oprea, A.; Palomo-Pinto, F. R.; Paradela, C.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, J. I.; Praena, J.; Quesada, J. M.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Robles, M. S.; Rout, P. C.; Rubbia, C.; Ryan, J. A.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Sedyshev, P.; Smith, A. G.; Suryanarayana, S. V.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlastou, R.; Wallner, A.; Warren, S.; Weigand, M.; Wolf, C.; Woods, P. J.; Weiss, C.; Wright, T.

    2017-10-01

    A new high flux experimental area has recently become operational at the n_TOF facility at CERN. This new measuring station, n_TOF-EAR2, is placed at the end of a vertical beam line at a distance of approximately 20m from the spallation target. The characterization of the neutron beam, in terms of flux, spatial profile and resolution function, is of crucial importance for the feasibility study and data analysis of all measurements to be performed in the new area. In this paper, the measurement of the neutron flux, performed with different solid-state and gaseous detection systems, and using three neutron-converting reactions considered standard in different energy regions is reported. The results of the various measurements have been combined, yielding an evaluated neutron energy distribution in a wide energy range, from 2meV to 100MeV, with an accuracy ranging from 2%, at low energy, to 6% in the high-energy region. In addition, an absolute normalization of the n_TOF-EAR2 neutron flux has been obtained by means of an activation measurement performed with 197Au foils in the beam.

  9. Estimating terrestrial uranium and thorium by antineutrino flux measurements.

    PubMed

    Dye, Stephen T; Guillian, Eugene H

    2008-01-08

    Uranium and thorium within the Earth produce a major portion of terrestrial heat along with a measurable flux of electron antineutrinos. These elements are key components in geophysical and geochemical models. Their quantity and distribution drive the dynamics, define the thermal history, and are a consequence of the differentiation of the Earth. Knowledge of uranium and thorium concentrations in geological reservoirs relies largely on geochemical model calculations. This article describes the methods and criteria to experimentally determine average concentrations of uranium and thorium in the continental crust and in the mantle by using site-specific measurements of the terrestrial antineutrino flux. Optimal, model-independent determinations involve significant exposures of antineutrino detectors remote from nuclear reactors at both a midcontinental and a midoceanic site. This would require major, new antineutrino detection projects. The results of such projects could yield a greatly improved understanding of the deep interior of the Earth.

  10. Estimating terrestrial uranium and thorium by antineutrino flux measurements

    PubMed Central

    Dye, Stephen T.; Guillian, Eugene H.

    2008-01-01

    Uranium and thorium within the Earth produce a major portion of terrestrial heat along with a measurable flux of electron antineutrinos. These elements are key components in geophysical and geochemical models. Their quantity and distribution drive the dynamics, define the thermal history, and are a consequence of the differentiation of the Earth. Knowledge of uranium and thorium concentrations in geological reservoirs relies largely on geochemical model calculations. This article describes the methods and criteria to experimentally determine average concentrations of uranium and thorium in the continental crust and in the mantle by using site-specific measurements of the terrestrial antineutrino flux. Optimal, model-independent determinations involve significant exposures of antineutrino detectors remote from nuclear reactors at both a midcontinental and a midoceanic site. This would require major, new antineutrino detection projects. The results of such projects could yield a greatly improved understanding of the deep interior of the Earth. PMID:18172211

  11. A closed-chamber method to measure greenhouse gas fluxes from dry aquatic sediments

    NASA Astrophysics Data System (ADS)

    Lesmeister, Lukas; Koschorreck, Matthias

    2017-06-01

    Recent research indicates that greenhouse gas (GHG) emissions from dry aquatic sediments are a relevant process in the freshwater carbon cycle. However, fluxes are difficult to measure because of the often rocky substrate and the dynamic nature of the habitat. Here we tested the performance of different materials to seal a closed chamber to stony ground both in laboratory and field experiments. Using on-site material consistently resulted in elevated fluxes. The artefact was caused both by outgassing of the material and production of gas. The magnitude of the artefact was site dependent - the measured CO2 flux increased between 10 and 208 %. Errors due to incomplete sealing proved to be more severe than errors due to non-inert sealing material.Pottery clay as sealing material provided a tight seal between the chamber and the ground and no production of gases was detected. With this approach it is possible to get reliable gas fluxes from hard-substrate sites without using a permanent collar. Our test experiments confirmed that CO2 fluxes from dry aquatic sediments are similar to CO2 fluxes from terrestrial soils.

  12. Quantitative evaluation of high-energy O- ion particle flux in a DC magnetron sputter plasma with an indium-tin-oxide target

    NASA Astrophysics Data System (ADS)

    Suyama, Taku; Bae, Hansin; Setaka, Kenta; Ogawa, Hayato; Fukuoka, Yushi; Suzuki, Haruka; Toyoda, Hirotaka

    2017-11-01

    O- ion flux from the indium tin oxide (ITO) sputter target under Ar ion bombardment is quantitatively evaluated using a calorimetry method. Using a mass spectrometer with an energy analyzer, O- energy distribution is measured with spatial dependence. Directional high-energy O- ion ejected from the target surface is observed. Using a calorimetry method, localized heat flux originated from high-energy O- ion is measured. From absolute evaluation of the heat flux from O- ion, O- particle flux in order of 1018 m-2 s-1 is evaluated at a distance of 10 cm from the target. Production yield of O- ion on the ITO target by one Ar+ ion impingement at a kinetic energy of 244 eV is estimated to be 3.3  ×  10-3 as the minimum value.

  13. KASCADE-Grande Limits on the Isotropic Diffuse Gamma-Ray Flux between 100 TeV and 1 EeV

    NASA Astrophysics Data System (ADS)

    Apel, W. D.; Arteaga-Velázquez, J. C.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Feng, Z.; Fuhrmann, D.; Gherghel-Lascu, A.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huege, T.; Kampert, K.-H.; Kang, D.; Klages, H. O.; Link, K.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Oehlschläger, J.; Ostapchenko, S.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schoo, S.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Zabierowski, J.; KASCADE-Grande Collaboration

    2017-10-01

    KASCADE and KASCADE-Grande were multi-detector installations to measure individual air showers of cosmic rays at ultra-high energy. Based on data sets measured by KASCADE and KASCADE-Grande, 90% C.L. upper limits to the flux of gamma-rays in the primary cosmic ray flux are determined in an energy range of {10}14{--}{10}18 eV. The analysis is performed by selecting air showers with a low muon content as expected for gamma-ray-induced showers compared to air showers induced by energetic nuclei. The best upper limit of the fraction of gamma-rays to the total cosmic ray flux is obtained at 3.7× {10}15 eV with 1.1× {10}-5. Translated to an absolute gamma-ray flux this sets constraints on some fundamental astrophysical models, such as the distance of sources for at least one of the IceCube neutrino excess models.

  14. Absolute atomic hydrogen densities in a radio frequency discharge measured by two-photon laser induced fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Chérigier, L.; Czarnetzki, U.; Luggenhölscher, D.; Schulz-von der Gathen, V.; Döbele, H. F.

    1999-01-01

    Absolute atomic hydrogen densities were measured in the gaseous electronics conference reference cell parallel plate reactor by Doppler-free two-photon absorption laser induced fluorescence spectroscopy (TALIF) at λ=205 nm. The capacitively coupled radio frequency discharge was operated at 13.56 MHz in pure hydrogen under various input power and pressure conditions. The Doppler-free excitation technique with an unfocused laser beam together with imaging the fluorescence radiation by an intensified charge coupled device camera allows instantaneous spatial resolution along the radial direction. Absolute density calibration is obtained with the aid of a flow tube reactor and titration with NO2. The influence of spatial intensity inhomogenities along the laser beam and subsequent fluorescence are corrected by TALIF in xenon. A full mapping of the absolute density distribution between the electrodes was obtained. The detection limit for atomic hydrogen amounts to about 2×1018 m-3. The dissociation degree is of the order of a few percent.

  15. Heat flux microsensor measurements and calibrations

    NASA Technical Reports Server (NTRS)

    Terrell, James P.; Hager, Jon M.; Onishi, Shinzo; Diller, Thomas E.

    1992-01-01

    A new thin-film heat flux gage has been fabricated specifically for severe high temperature operation using platinum and platinum-10 percent rhodium for the thermocouple elements. Radiation calibrations of this gage were performed at the AEDC facility over the available heat flux range (approx. 1.0 - 1,000 W/cu cm). The gage output was linear with heat flux with a slight increase in sensitivity with increasing surface temperature. Survivability of gages was demonstrated in quench tests from 500 C into liquid nitrogen. Successful operation of gages to surface temperatures of 750 C has been achieved. No additional cooling of the gages is required because the gages are always at the same temperature as the substrate material. A video of oxyacetylene flame tests with real-time heat flux and temperature output is available.

  16. Estimating regional methane surface fluxes: the relative importance of surface and GOSAT mole fraction measurements

    NASA Astrophysics Data System (ADS)

    Fraser, A.; Palmer, P. I.; Feng, L.; Boesch, H.; Cogan, A.; Parker, R.; Dlugokencky, E. J.; Fraser, P. J.; Krummel, P. B.; Langenfelds, R. L.; O'Doherty, S.; Prinn, R. G.; Steele, L. P.; van der Schoot, M.; Weiss, R. F.

    2013-06-01

    We use an ensemble Kalman filter (EnKF), together with the GEOS-Chem chemistry transport model, to estimate regional monthly methane (CH4) fluxes for the period June 2009-December 2010 using proxy dry-air column-averaged mole fractions of methane (XCH4) from GOSAT (Greenhouse gases Observing SATellite) and/or NOAA ESRL (Earth System Research Laboratory) and CSIRO GASLAB (Global Atmospheric Sampling Laboratory) CH4 surface mole fraction measurements. Global posterior estimates using GOSAT and/or surface measurements are between 510-516 Tg yr-1, which is less than, though within the uncertainty of, the prior global flux of 529 ± 25 Tg yr-1. We find larger differences between regional prior and posterior fluxes, with the largest changes in monthly emissions (75 Tg yr-1) occurring in Temperate Eurasia. In non-boreal regions the error reductions for inversions using the GOSAT data are at least three times larger (up to 45%) than if only surface data are assimilated, a reflection of the greater spatial coverage of GOSAT, with the two exceptions of latitudes >60° associated with a data filter and over Europe where the surface network adequately describes fluxes on our model spatial and temporal grid. We use CarbonTracker and GEOS-Chem XCO2 model output to investigate model error on quantifying proxy GOSAT XCH4 (involving model XCO2) and inferring methane flux estimates from surface mole fraction data and show similar resulting fluxes, with differences reflecting initial differences in the proxy value. Using a series of observing system simulation experiments (OSSEs) we characterize the posterior flux error introduced by non-uniform atmospheric sampling by GOSAT. We show that clear-sky measurements can theoretically reproduce fluxes within 10% of true values, with the exception of tropical regions where, due to a large seasonal cycle in the number of measurements because of clouds and aerosols, fluxes are within 15% of true fluxes. We evaluate our posterior methane

  17. Estimating regional methane surface fluxes: the relative importance of surface and GOSAT mole fraction measurements

    NASA Astrophysics Data System (ADS)

    Fraser, A.; Palmer, P. I.; Feng, L.; Boesch, H.; Cogan, A.; Parker, R.; Dlugokencky, E. J.; Fraser, P. J.; Krummel, P. B.; Langenfelds, R. L.; O'Doherty, S.; Prinn, R. G.; Steele, L. P.; van der Schoot, M.; Weiss, R. F.

    2012-12-01

    We use an ensemble Kalman filter (EnKF), together with the GEOS-Chem chemistry transport model, to estimate regional monthly methane (CH4) fluxes for the period June 2009-December 2010 using proxy dry-air column-averaged mole fractions of methane (XCH4) from GOSAT (Greenhouse gases Observing SATellite) and/or NOAA ESRL (Earth System Research Laboratory) and CSIRO GASLAB (Global Atmospheric Sampling Laboratory) CH4 surface mole fraction measurements. Global posterior estimates using GOSAT and/or surface measurements are between 510-516 Tg yr-1, which is less than, though within the uncertainty of, the prior global flux of 529 ± 25 Tg yr-1. We find larger differences between regional prior and posterior fluxes, with the largest changes (75 Tg yr-1) occurring in Temperate Eurasia. In non-boreal regions the error reductions for inversions using the GOSAT data are at least three times larger (up to 45%) than if only surface data are assimilated, a reflection of the greater spatial coverage of GOSAT, with the two exceptions of latitudes > 60° associated with a data filter and over Europe where the surface network adequately describes fluxes on our model spatial and temporal grid. We use CarbonTracker and GEOS-Chem XCO2 model output to investigate model error on quantifying proxy GOSAT XCH4 (involving model XCO2) and inferring methane flux estimates from surface mole fraction data and show similar resulting fluxes, with differences reflecting initial differences in the proxy value. Using a series of observing system simulation experiments (OSSEs) we characterize the posterior flux error introduced by non-uniform atmospheric sampling by GOSAT. We show that clear-sky measurements can theoretically reproduce fluxes within 5% of true values, with the exception of South Africa and Tropical South America where, due to a large seasonal cycle in the number of measurements because of clouds and aerosols, fluxes are within 17% and 19% of true fluxes, respectively. We evaluate our

  18. High-flux source of low-energy neutral beams using reflection of ions from metals

    NASA Technical Reports Server (NTRS)

    Cuthbertson, John W.; Motley, Robert W.; Langer, William D.

    1992-01-01

    Reflection of low-energy ions from surfaces can be applied as a method of producing high-flux beams of low-energy neutral particles, and is an important effect in several areas of plasma technology, such as in the edge region of fusion devices. We have developed a beam source based on acceleration and reflection of ions from a magnetically confined coaxial RF plasma source. The beam provides a large enough flux to allow the energy distribution of the reflected neutrals to be measured despite the inefficiency of detection, by means of an electrostatic cylindrical mirror analyzer coupled with a quadrupole mass spectrometer. Energy distributions have been measured for oxygen, nitrogen, and inert gas ions incident with from 15 to 70 eV reflected from amorphous metal surfaces of several compositions. For ions of lighter atomic mass than the reflecting metal, reflected beams have peaked energy distributions; beams with the peak at 4-32 eV have been measured. The energy and mass dependences of the energy distributions as well as measurements of absolute flux, and angular distribution and divergence are reported. Applications of the neutral beams produced are described.

  19. Study on improving the turbidity measurement of the absolute coagulation rate constant.

    PubMed

    Sun, Zhiwei; Liu, Jie; Xu, Shenghua

    2006-05-23

    The existing theories dealing with the evaluation of the absolute coagulation rate constant by turbidity measurement were experimentally tested for different particle-sized (radius = a) suspensions at incident wavelengths (lambda) ranging from near-infrared to ultraviolet light. When the size parameter alpha = 2pi a/lambda > 3, the rate constant data from previous theories for fixed-sized particles show significant inconsistencies at different light wavelengths. We attribute this problem to the imperfection of these theories in describing the light scattering from doublets through their evaluation of the extinction cross section. The evaluations of the rate constants by all previous theories become untenable as the size parameter increases and therefore hampers the applicable range of the turbidity measurement. By using the T-matrix method, we present a robust solution for evaluating the extinction cross section of doublets formed in the aggregation. Our experiments show that this new approach is effective in extending the applicability range of the turbidity methodology and increasing measurement accuracy.

  20. Imposing strong constraints on tropical terrestrial CO2 fluxes using passenger aircraft based measurements

    NASA Astrophysics Data System (ADS)

    Niwa, Yosuke; Machida, Toshinobu; Sawa, Yousuke; Matsueda, Hidekazu; Schuck, Tanja J.; Brenninkmeijer, Carl A. M.; Imasu, Ryoichi; Satoh, Masaki

    2012-06-01

    Because very few measurements of atmospheric carbon dioxide (CO2) are available in the tropics, estimates of surface CO2 fluxes in tropical regions are beset with considerable uncertainties. To improve estimates of tropical terrestrial fluxes, atmospheric CO2 inversion was performed using passenger aircraft based measurements of the Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) project in addition to the surface measurement data set of GLOBALVIEW-CO2. Regional monthly fluxes at the earth's surface were estimated using the Bayesian synthesis approach focusing on the period 2006-2008 using the Nonhydrostatic Icosahedral Atmospheric Model-based Transport Model (NICAM-TM). By adding the aircraft to the surface data, the posterior flux errors were greatly reduced; specifically, error reductions of up to 64% were found for tropical Asia regions. This strong impact is closely related to efficient vertical transport in the tropics. The optimized surface fluxes using the CONTRAIL data were evaluated by comparing the simulated atmospheric CO2 distributions with independent aircraft measurements of the Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC) project. The inversion with the CONTRAIL data yields the global carbon sequestration rates of 2.22 ± 0.28 Pg C yr-1 for the terrestrial biosphere and 2.24 ± 0.27 Pg C yr-1 for the oceans (the both are adjusted by riverine input of CO2). For the first time the CONTRAIL CO2 measurements were used in an inversion system to identify the areas of greatest impact in terms of reducing flux uncertainties.

  1. Potentials and challenges associated with automated closed dynamic chamber measurements of soil CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Görres, Carolyn-Monika; Kammann, Claudia; Ceulemans, Reinhart

    2015-04-01

    Soil respiration fluxes are influenced by natural factors such as climate and soil type, but also by anthropogenic activities in managed ecosystems. As a result, soil CO2 fluxes show a large intra- and interannual as well as intra- and intersite variability. Most of the available soil CO2 flux data giving insights into this variability have been measured with manually closed static chambers, but technological advances in the past 15 years have also led to an increased use of automated closed chamber systems. The great advantage of automated chambers in comparison to manually operated chambers is the higher temporal resolution of the flux data. This is especially important if we want to better understand the effects of short-term events, e.g. fertilization or heavy rainfall, on soil CO2 flux variability. However, the chamber method is an invasive measurement method which can potentially alter soil CO2 fluxes and lead to biased measurement results. In the peer-reviewed literature, many papers compare the field performance and results of different closed static chamber designs, or compare manual chambers with automated chamber systems, to identify potential biases in CO2 flux measurements, and thus help to reduce uncertainties in the flux data. However, inter-comparisons of different automated closed dynamic chamber systems are still lacking. Here we are going to present a field comparison of the most-cited automated chamber system, the LI-8100A Automated Soil Flux System, with the also commercially available Greenhouse Gas Monitoring System AGPS. Both measurement systems were installed side by side at a recently harvested poplar bioenergy plantation (POPFULL, http://uahost.uantwerpen.be/popfull/) from April 2014 until August 2014. The plantation provided optimal comparison conditions with a bare field situation after the harvest and a regrowing canopy resulting in a broad variety of microclimates. Furthermore, the plantation was planted in a double-row system with

  2. An ecosystem-scale perspective of the net land methanol flux. Synthesis of micrometeorological flux measurements

    DOE PAGES

    Wohlfahrt, G.; Amelynck, C.; Ammann, C.; ...

    2015-07-09

    Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates, reflecting uncertainties in the approaches used to model and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis ofmore » the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land–atmosphere methanol exchange. Our study shows that the controls of plant growth on production, and thus the methanol emission magnitude, as well as stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; however, they are neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow for full advantage to be

  3. An ecosystem-scale perspective of the net land methanol flux: synthesis of micrometeorological flux measurements

    PubMed Central

    Wohlfahrt, G.; Amelynck, C.; Ammann, C.; Arneth, A.; Bamberger, I.; Goldstein, A. H.; Gu, L.; Guenther, A.; Hansel, A.; Heinesch, B.; Holst, T.; Hörtnagl, L.; Karl, T.; Laffineur, Q.; Neftel, A.; McKinney, K.; Munger, J. W.; Pallardy, S. G.; Schade, G. W.; Seco, R.; Schoon, N.

    2015-01-01

    Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates reflecting uncertainties in the approaches used to model, and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land–atmosphere methanol exchange. Our study shows that the controls of plant growth on the production, and thus the methanol emission magnitude, and stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem-level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; they are however neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow taking full advantage of the rich

  4. Why we need to estimate the sampling uncertainty of eddy covariance flux measurement?

    NASA Astrophysics Data System (ADS)

    Kim, W.; Seo, H. H.

    2015-12-01

    Fruitful studies on exchanges of energy, water and carbon dioxide between the atmosphere and terrestrial ecosystem has been produced under a global network (http://fluxnet.ornl.gov). The exchange is defined by a flux, and in traditional the flux is estimated with eddy covariance (EC) method as a mean flux F for 30-min or 1-hr, because no techniques have been established for a direct measurement of a momentary flux itself. Therefore, the exchange analysis with F is to paid attention to estimations of spatial or temporal mean, because the exchange estimated by arithmetic mean Fa might be inappropriate in terms of the sample F used in this averaging having nonidentical inherent quality within one another in accordance with different micrometeorological and ecophysiological conditions while those are measured by the same instruments. To overcome this issue, we propose the weighted mean Fw using a relative sampling uncertainty ɛ estimated by a sampling F and its uncertainty, and introduce Fw performance tested with EC measurements for various sites.

  5. SU-F-T-472: Validation of Absolute Dose Measurements for MR-IGRT With and Without Magnetic Field

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Green, O; Li, H; Goddu, S

    Purpose: To validate absolute dose measurements for a MR-IGRT system without presence of the magnetic field. Methods: The standard method (AAPM’s TG-51) of absolute dose measurement with ionization chambers was tested with and without the presence of the magnetic field for a clinical 0.32-T Co-60 MR-IGRT system. Two ionization chambers were used - the Standard Imaging (Madison, WI) A18 (0.123 cc) and the PTW (Freiburg, Germany). A previously reported Monte Carlo simulation suggested a difference on the order of 0.5% for dose measured with and without the presence of the magnetic field, but testing this was not possible until anmore » engineering solution to allow the radiation system to be used without the nominal magnetic field was found. A previously identified effect of orientation in the magnetic field was also tested by placing the chamber either parallel or perpendicular to the field and irradiating from two opposing angles (90 and 270). Finally, the Imaging and Radiation Oncology Core provided OSLD detectors for five irradiations each with and without the field - with two heads at both 0 and 90 degrees, and one head at 90 degrees only as it doesn’t reach 0 (IEC convention). Results: For the TG-51 comparison, expected dose was obtained by decaying values measured at the time of source installation. The average measured difference was 0.4%±0.12% for A18 and 0.06%±0.15% for Farmer chamber. There was minimal (0.3%) orientation dependence without the magnetic field for the A18 chamber, while previous measurements with the magnetic field had a deviation of 3.2% with chamber perpendicular to magnetic field. Results reported by IROC for the OSLDs with and without the field had a maximum difference of 2%. Conclusion: Accurate absolute dosimetry was verified by measurement under the same conditions with and without the magnetic field for both ionization chambers and independently-verifiable OSLDs.« less

  6. Wind Tunnel Measurement of Turbulent and Advective Scalar Fluxes: A Case Study on Intersection Ventilation

    PubMed Central

    Kukačka, Libor; Nosek, Štĕpán; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

    2012-01-01

    The objective of this study is to determine processes of pollution ventilation in the X-shaped street intersection in an idealized symmetric urban area for the changing approach flow direction. A unique experimental setup for simultaneous wind tunnel measurement of the flow velocity and the tracer gas concentration in a high temporal resolution is assembled. Advective horizontal and vertical scalar fluxes are computed from averaged measured velocity and concentration data within the street intersection. Vertical advective and turbulent scalar fluxes are computed from synchronized velocity and concentration signals measured in the plane above the intersection. All the results are obtained for five approach flow directions. The influence of the approach flow on the advective and turbulent fluxes is determined. The contribution of the advective and turbulent flux to the ventilation is discussed. Wind direction with the best dispersive conditions in the area is found. The quadrant analysis is applied to the synchronized signals of velocity and concentration fluctuation to determine events with the dominant contribution to the momentum flux and turbulent scalar flux. PMID:22649290

  7. Wind tunnel measurement of turbulent and advective scalar fluxes: a case study on intersection ventilation.

    PubMed

    Kukačka, Libor; Nosek, Štĕpán; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

    2012-01-01

    The objective of this study is to determine processes of pollution ventilation in the X-shaped street intersection in an idealized symmetric urban area for the changing approach flow direction. A unique experimental setup for simultaneous wind tunnel measurement of the flow velocity and the tracer gas concentration in a high temporal resolution is assembled. Advective horizontal and vertical scalar fluxes are computed from averaged measured velocity and concentration data within the street intersection. Vertical advective and turbulent scalar fluxes are computed from synchronized velocity and concentration signals measured in the plane above the intersection. All the results are obtained for five approach flow directions. The influence of the approach flow on the advective and turbulent fluxes is determined. The contribution of the advective and turbulent flux to the ventilation is discussed. Wind direction with the best dispersive conditions in the area is found. The quadrant analysis is applied to the synchronized signals of velocity and concentration fluctuation to determine events with the dominant contribution to the momentum flux and turbulent scalar flux.

  8. ScaRaB: first results of absolute and cross calibration

    NASA Astrophysics Data System (ADS)

    Trémas, Thierry L.; Aznay, Ouahid; Chomette, Olivier

    2015-10-01

    ScaRaB (SCAnner for RAdiation Budget) is the name of three radiometers whose two first flight models have been launched in 1994 and 1997. The instruments were mounted on-board Russian satellites, METEOR and RESURS. On October 12th 2011, a last model has been launched from the Indian site of Sriharikota. ScaRaB is a passenger of MEGHA-TROPIQUES, an Indo-French joint Satellite Mission for studying the water cycle and energy exchanges in the tropics. ScaRaB is composed of four parallel and independent channels. Channel-2 and channel-3 are considered as the main ones. Channel-1 is dedicated to measure solar radiance (0.5 to 0.7 μm) while channel-4 (10 to 13 μm) is an infrared window. The absolute calibration of ScaRab is assured by internal calibration sources (black bodies and a lamp for channel-1). However, during the commissioning phase, the lamp used for the absolute calibration of channel-1 revealed to be inaccurate. We propose here an alternative calibration method based on terrestrial targets. Due to the spectral range of channel-1, only calibration over desert sites (temporal monitoring) and clouds (cross band) is suitable. Desert sites have been widely used for sensor calibration since they have a stable spectral response over time. Because of their high reflectances, the atmospheric effect on the upward radiance is relatively minimal. In addition, they are spatially uniform. Their temporal instability without atmospheric correction has been determined to be less than 1-2% over a year. Very-high-altitude (10 km) bright clouds are good validation targets in the visible and near-infrared spectra because of their high spectrally consistent reflectance. If the clouds are very high, there is no need to correct aerosol scattering and water vapor absorption as both aerosol and water vapor are distributed near the surface. Only Rayleigh scattering and ozone absorption need to be considered. This method has been found to give a 4% uncertainty. Radiometric cross

  9. Hilbertian sine as an absolute measure of Bayesian inference in ISR, homeland security, medicine, and defense

    NASA Astrophysics Data System (ADS)

    Jannson, Tomasz; Wang, Wenjian; Hodelin, Juan; Forrester, Thomas; Romanov, Volodymyr; Kostrzewski, Andrew

    2016-05-01

    In this paper, Bayesian Binary Sensing (BBS) is discussed as an effective tool for Bayesian Inference (BI) evaluation in interdisciplinary areas such as ISR (and, C3I), Homeland Security, QC, medicine, defense, and many others. In particular, Hilbertian Sine (HS) as an absolute measure of BI, is introduced, while avoiding relativity of decision threshold identification, as in the case of traditional measures of BI, related to false positives and false negatives.

  10. Airflows and turbulent flux measurements in mountainous terrain: Part 2: Mesoscale effects

    USGS Publications Warehouse

    Turnipseed, A.A.; Anderson, D.E.; Burns, S.; Blanken, P.D.; Monson, Russell K.

    2004-01-01

    The location of the Niwot Ridge Ameriflux site within the rocky mountains subjects it to airflows which are common in mountainous terrain. In this study, we examine the effects of some of these mesoscale features on local turbulent flux measurements; most notably, the formation of valley/mountain flows and mountain lee-side waves. The valley/mountain flows created local non-stationarities in the wind flow caused by the passage of a lee-side convergence zone (LCZ) in which upslope and downslope flows met in the vicinity of the measurement tower. During June-August, 2001, possible lee-side convergences were flagged for ???26% of all half-hour daytime flux measurement periods. However, there was no apparent loss of flux during these periods. On some relatively stable, summer nights, turbulence (designated via ??w), and scalar fluctuations (temperature and CO2, for example) exhibited periodicities that appeared congruent with passage of low frequency gravity waves (?? ??? 20 min). Spectral peaks at 0.0008 Hz (20 min) in both vertical velocity and scalar spectra were observed and indicated that 25-50% of the total scalar covariances were accounted for by the low frequency waves. During some periods of strong westerly winds (predominantly in winter), large mountain gravity waves were observed to form. Typically, the flux tower resided within a region of downslope "shooting flow", which created high turbulence, but had no detrimental effect on local flux measurements based on valid turbulence statistics and nearly complete energy budget closure. Periodically, we found evidence for re-circulating, rotor winds in the simultaneous time series of wind data from the Ameriflux tower site and a second meteorological site situated 8 km upslope and to the West. Only 14% of the half-hour time periods that we examined for a 4 month period in the winter of 2000-2001 indicated the possible existence of rotor winds. On average, energy budget closure was ???20% less during periods with

  11. Non-Invasive Method of Determining Absolute Intracranial Pressure

    NASA Technical Reports Server (NTRS)

    Yost, William T. (Inventor); Cantrell, John H., Jr. (Inventor); Hargens, Alan E. (Inventor)

    2004-01-01

    A method is presented for determining absolute intracranial pressure (ICP) in a patient. Skull expansion is monitored while changes in ICP are induced. The patient's blood pressure is measured when skull expansion is approximately zero. The measured blood pressure is indicative of a reference ICP value. Subsequently, the method causes a known change in ICP and measured the change in skull expansion associated therewith. The absolute ICP is a function of the reference ICP value, the known change in ICP and its associated change in skull expansion; and a measured change in skull expansion.

  12. Online absolute pose compensation and steering control of industrial robot based on six degrees of freedom laser measurement

    NASA Astrophysics Data System (ADS)

    Yang, Juqing; Wang, Dayong; Fan, Baixing; Dong, Dengfeng; Zhou, Weihu

    2017-03-01

    In-situ intelligent manufacturing for large-volume equipment requires industrial robots with absolute high-accuracy positioning and orientation steering control. Conventional robots mainly employ an offline calibration technology to identify and compensate key robotic parameters. However, the dynamic and static parameters of a robot change nonlinearly. It is not possible to acquire a robot's actual parameters and control the absolute pose of the robot with a high accuracy within a large workspace by offline calibration in real-time. This study proposes a real-time online absolute pose steering control method for an industrial robot based on six degrees of freedom laser tracking measurement, which adopts comprehensive compensation and correction of differential movement variables. First, the pose steering control system and robot kinematics error model are constructed, and then the pose error compensation mechanism and algorithm are introduced in detail. By accurately achieving the position and orientation of the robot end-tool, mapping the computed Jacobian matrix of the joint variable and correcting the joint variable, the real-time online absolute pose compensation for an industrial robot is accurately implemented in simulations and experimental tests. The average positioning error is 0.048 mm and orientation accuracy is better than 0.01 deg. The results demonstrate that the proposed method is feasible, and the online absolute accuracy of a robot is sufficiently enhanced.

  13. Measurements of plasma sheath heat flux in the Alcator C-Mod divertor

    NASA Astrophysics Data System (ADS)

    Brunner, Dan; Labombard, Brian; Terry, Jim; Reinke, Matt

    2010-11-01

    Heat flux is one of the most important parameters controlling the lifetime of first-wall components in fusion experiments and reactors. The sheath heat flux coefficient (γ) is a parameter relating heat flux (from a plasma to a material surface) to the electron temperature and ion saturation current. Being such a simple expression for a kinetic process, it is of great interest to plasma edge fluid modelers. Under the assumptions of equal ion and electron temperatures, no secondary electron emission, and no net current to the surface the value of γ is approximately 7 [1]. Alcator C-Mod provides a unique opportunity among today's experiments to measure reactor-relevant heat fluxes (100's of MW/m^2 parallel to the magnetic field) in reactor-like divertor geometry. Motivated by the DoE 2010 joint milestone to measure heat flux footprints, the lower outer divertor of Alcator has been instrumented with a suite of Langmuir probes, novel surface thermocouples, and calorimeters in tiles purposefully ramped to eliminate shadowing; all within view of an IR camera. Initial results indicate that the experimentally inferred values of γ are found to agree with simple theory in the sheath limited regime and diverges to lower values as the density increases.

  14. Measurement of OEF and absolute CMRO2: MRI-based methods using interleaved and combined hypercapnia and hyperoxia

    PubMed Central

    Wise, Richard G.; Harris, Ashley D.; Stone, Alan; Murphy, Kevin

    2014-01-01

    Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (FMRI) is most commonly used in a semi-quantitative manner to infer changes in brain activity. Despite the basis of the image contrast lying in the cerebral venous blood oxygenation level, quantification of absolute cerebral metabolic rate of oxygen consumption (CMRO2) has only recently been demonstrated. Here we examine two approaches to the calibration of FMRI signal to measure absolute CMRO2 using hypercapnic and hyperoxic respiratory challenges. The first approach is to apply hypercapnia and hyperoxia separately but interleaved in time and the second is a combined approach in which we apply hyperoxic challenges simultaneously with different levels of hypercapnia. Eleven healthy volunteers were studied at 3T using a dual gradient-echo spiral readout pulsed arterial spin labelling (ASL) imaging sequence. Respiratory challenges were conducted using an automated system of dynamic end-tidal forcing. A generalised BOLD signal model was applied, within a Bayesian estimation framework, that aims to explain the effects of modulation of CBF and arterial oxygen content to estimate venous deoxyhaemoglobin concentration ([dHb]0). Using CBF measurements combined with the estimated oxygen extraction fraction (OEF), absolute CMRO2 was calculated. The interleaved approach to hypercapnia and hyperoxia, as well as yielding estimates of CMRO2 and OEF demonstrated a significant increase in regional CBF, venous oxygen saturation (SvO2) (a decrease in OEF) and absolute CMRO2 in visual cortex in response to a continuous (20 minute) visual task, demonstrating the potential for the method in measuring long term changes in CMRO2. The combined approach to oxygen and carbon dioxide modulation, as well as taking less time to acquire data, yielded whole brain grey matter estimates of CMRO2 and OEF of 184±45 μmol/100g/min and 0.42±0.12 respectively, along with additional estimates of the vascular parameters

  15. Evapotranspiration: Mass balance measurements compared with flux estimation methods

    USDA-ARS?s Scientific Manuscript database

    Evapotranspiration (ET) may be measured by mass balance methods and estimated by flux sensing methods. The mass balance methods are typically restricted in terms of the area that can be represented (e.g., surface area of weighing lysimeter (LYS) or equivalent representative area of neutron probe (NP...

  16. Comparison of buried soil sensors, surface chambers and above ground measurements of carbon dioxide fluxes

    USDA-ARS?s Scientific Manuscript database

    Soil carbon dioxide (CO2) flux is an important component of the terrestrial carbon cycle. Accurate measurements of soil CO2 flux aids determinations of carbon budgets. In this study, we investigated soil CO2 fluxes with time and depth and above ground CO2 fluxes in a bare field. CO2 concentrations w...

  17. 3D-Printed Detector Band for Magnetic Off-Plane Flux Measurements in Laminated Machine Cores.

    PubMed

    Shilyashki, Georgi; Pfützner, Helmut; Palkovits, Martin; Windischhofer, Andreas; Giefing, Markus

    2017-12-19

    Laminated soft magnetic cores of transformers, rotating machines etc. may exhibit complex 3D flux distributions with pronounced normal fluxes (off-plane fluxes), perpendicular to the plane of magnetization. As recent research activities have shown, detections of off-plane fluxes tend to be essential for the optimization of core performances aiming at a reduction of core losses and of audible noise. Conventional sensors for off-plane flux measurements tend to be either of high thickness, influencing the measured fluxes significantly, or require laborious preparations. In the current work, thin novel detector bands for effective and simple off-plane flux detections in laminated machine cores were manufactured. They are printed in an automatic way by an in-house developed 3D/2D assembler. The latter enables a unique combination of conductive and non-conductive materials. The detector bands were effectively tested in the interior of a two-package, three-phase model transformer core. They proved to be mechanically resilient, even for strong clamping of the core.

  18. Turbulent heat flux measurements in a transitional boundary layer

    NASA Technical Reports Server (NTRS)

    Sohn, K. H.; Zaman, K. B. M. Q.; Reshotko, E.

    1992-01-01

    During an experimental investigation of the transitional boundary layer over a heated flat plate, an unexpected result was encountered for the turbulent heat flux (bar-v't'). This quantity, representing the correlation between the fluctuating normal velocity and the temperature, was measured to be negative near the wall under certain conditions. The result was unexpected as it implied a counter-gradient heat transfer by the turbulent fluctuations. Possible reasons for this anomalous result were further investigated. The possible causes considered for this negative bar-v't' were: (1) plausible measurement error and peculiarity of the flow facility, (2) large probe size effect, (3) 'streaky structure' in the near wall boundary layer, and (4) contributions from other terms usually assumed negligible in the energy equation including the Reynolds heat flux in the streamwise direction (bar-u't'). Even though the energy balance has remained inconclusive, none of the items (1) to (3) appear to be contributing directly to the anomaly.

  19. Polarized BRDF measurement of steel E235B in the near-infrared region: Based on a self-designed instrument with absolute measuring method

    NASA Astrophysics Data System (ADS)

    Liu, Yanlei; Yu, Kun; Liu, Zilong; Zhao, Yuejin; Liu, Yufang

    2018-06-01

    The spectral bidirectional reflectance distribution (BRDF) offers a complete description of the optical properties of the opaque material. Numerous studies on BRDF have been conducted for its important role in scientific research and industrial production. However, most of these studies focus on the visible region and unpolarized BRDF, and the spectral polarized BRDF in the near-infrared region is rarely reported. In this letter, we propose an absolute method to measure the spectral BRDF in the near-infrared region, and the detailed derivation is presented. A self-designed instrument is set up for the absolute measurement of BRDF. The reliability of this method is verified by comparing the experimental data of the three metal (aluminum, silver and gold) mirrors with the reference data. The in-plane polarized BRDF of steel E235B are measured, and the influence of incident angle and roughness on the BRDF are discussed. The degree of linear polarization (DOLP) are determined based on the polarized BRDF. The results indicate that both the roughness and incident angle have distinct influence on the BRDF and DOLP.

  20. Momentum Flux Measuring Instrument for Neutral and Charged Particle Flows

    NASA Technical Reports Server (NTRS)

    Chavers, Greg; Chang-Diaz, Franklin; Schafer, Charles F. (Technical Monitor)

    2002-01-01

    An instrument to measure the momentum flux (total pressure) of plasma and neutral particle jets onto a surface has been developed. While this instrument was developed for magnetized plasmas, the concept works for non-magnetized plasmas as well. We have measured forces as small as 10(exp -4) Newtons on a surface immersed in the plasma where small forces are due to ionic and neutral particles with kinetic energies on the order of a few eV impacting the surface. This instrument, a force sensor, uses a target plate (surface) that is immersed in the plasma and connected to one end of an alumina rod while the opposite end of the alumina rod is mechanically connected to a titanium beam on which four strain gauges are mounted. The force on the target generates torque causing strain in the beam. The resulting strain measurements can be correlated to a force on the target plate. The alumina rod electrically and thermally isolates the target plate from the strain gauge beam and allows the strain gauges to be located out of the plasma flow while also serving as a moment arm of several inches to increase the strain in the beam at the strain gauge location. These force measurements correspond directly to momentum flux and may be used with known plasma conditions to place boundaries on the kinetic energies of the plasma and neutral particles. The force measurements may also be used to infer thrust produced by a plasma propulsive device. Stainless steel, titanium, molybdenum, and aluminum flat target plates have been used. Momentum flux measurements of H2, D2, He, and Ar plasmas produced in a magnetized plasma device have been performed.

  1. LEAF, BRANCH, STAND & LANDSCAPE SCALE MEASUREMENTS OF VOLATILE ORGANIC COMPOUND FLUXES FROM U.S. WOODLANDS

    EPA Science Inventory

    Natural volatile organic compounds (VOC) fluxes were measured in three U.S. woodlands in summer 1993. Fluxes from individual leaves and branches were estimated with enclosure techniques and used to initialize and evaluate VOC emission model estimates. Ambient measurements were us...

  2. Effects of measurement resolution on the analysis of temperature time series for stream-aquifer flux estimation

    NASA Astrophysics Data System (ADS)

    Soto-López, Carlos D.; Meixner, Thomas; Ferré, Ty P. A.

    2011-12-01

    From its inception in the mid-1960s, the use of temperature time series (thermographs) to estimate vertical fluxes has found increasing use in the hydrologic community. Beginning in 2000, researchers have examined the impacts of measurement and parameter uncertainty on the estimates of vertical fluxes. To date, the effects of temperature measurement discretization (resolution), a characteristic of all digital temperature loggers, on the determination of vertical fluxes has not been considered. In this technical note we expand the analysis of recently published work to include the effects of temperature measurement resolution on estimates of vertical fluxes using temperature amplitude and phase shift information. We show that errors in thermal front velocity estimation introduced by discretizing thermographs differ when amplitude or phase shift data are used to estimate vertical fluxes. We also show that under similar circumstances sensor resolution limits the range over which vertical velocities are accurately reproduced more than uncertainty in temperature measurements, uncertainty in sensor separation distance, and uncertainty in the thermal diffusivity combined. These effects represent the baseline error present and thus the best-case scenario when discrete temperature measurements are used to infer vertical fluxes. The errors associated with measurement resolution can be minimized by using the highest-resolution sensors available. But thoughtful experimental design could allow users to select the most cost-effective temperature sensors to fit their measurement needs.

  3. Eddy covariance and lysimeter measurements of moisture fluxes over supraglacial debris

    NASA Astrophysics Data System (ADS)

    Brock, Benjamin

    2015-04-01

    Supraglacial debris covers have the potential to evaporate large quantities of water derived from either sub-debris ice melt or precipitation. Currently, knowledge of evaporation and condensation rates in supraglacial debris is limited due to the difficulty of making direct measurements. This paper presents eddy covariance and lysimeter measurements of moisture fluxes made over a 0.2 m debris layer at Miage debris covered glacier, Italian Alps, during the 2013 ablation season. The meteorological data are complimented by reflectometer measurements of volumetric water fraction in the saturated and vadose zones of the debris layer. The lysimeters were designed specifically to mimic the debris cover and were embedded within the debris matrix, level with the surface. Over the ablation season, the latent heat flux is dominated by evaporation, and the flux magnitude closely follows the daily cycle of daytime solar heating and night time radiative cooling of debris. Mean flux values are of the order of 1 kg m-2 day-1, but often higher for short periods following rainfall. Condensation rates are relatively small and restricted to night time and humid conditions when the debris-atmosphere vapour pressure gradient reverses due to relatively warm air overlying cold debris. The reflectometer measurements provide evidence of vertical water movement through capillary rise in the upper part of the fine-grained debris layer, just above the saturated horizon, and demonstrate how debris bulk water content increases after rainfall. The latent heat flux responds directly to changes in wind speed, indicating that atmospheric turbulence can penetrate porous upper debris layers to the saturated horizon. Hence, vertical sorting of debris sediments and antecedent rainfall are important in determining evaporation rates, in addition to current meteorological conditions. Comparison of lysimeter measurements with rainfall data provides an estimate that between 45% and 89% of rainfall is

  4. Microfabricated Collector-Generator Electrode Sensor for Measuring Absolute pH and Oxygen Concentrations.

    PubMed

    Dengler, Adam K; Wightman, R Mark; McCarty, Gregory S

    2015-10-20

    Fast-scan cyclic voltammetry (FSCV) has attracted attention for studying in vivo neurotransmission due to its subsecond temporal resolution, selectivity, and sensitivity. Traditional FSCV measurements use background subtraction to isolate changes in the local electrochemical environment, providing detailed information on fluctuations in the concentration of electroactive species. This background subtraction removes information about constant or slowly changing concentrations. However, determination of background concentrations is still important for understanding functioning brain tissue. For example, neural activity is known to consume oxygen and produce carbon dioxide which affects local levels of oxygen and pH. Here, we present a microfabricated microelectrode array which uses FSCV to detect the absolute levels of oxygen and pH in vitro. The sensor is a collector-generator electrode array with carbon microelectrodes spaced 5 μm apart. In this work, a periodic potential step is applied at the generator producing transient local changes in the electrochemical environment. The collector electrode continuously performs FSCV enabling these induced changes in concentration to be recorded with the sensitivity and selectivity of FSCV. A negative potential step applied at the generator produces a transient local pH shift at the collector. The generator-induced pH signal is detected using FSCV at the collector and correlated to absolute solution pH by postcalibration of the anodic peak position. In addition, in oxygenated solutions a negative potential step at the generator produces hydrogen peroxide by reducing oxygen. Hydrogen peroxide is detected with FSCV at the collector electrode, and the magnitude of the oxidative peak is proportional to absolute oxygen concentrations. Oxygen interference on the pH signal is minimal and can be accounted for with a postcalibration.

  5. Absolute Spatially- and Temporally-Resolved Optical Emission Measurements of rf Glow Discharges in Argon

    PubMed Central

    Djurović, S.; Roberts, J. R.; Sobolewski, M. A.; Olthoff, J. K.

    1993-01-01

    Spatially- and temporally-resolved measurements of optical emission intensities are presented from rf discharges in argon over a wide range of pressures (6.7 to 133 Pa) and applied rf voltages (75 to 200 V). Results of measurements of emission intensities are presented for both an atomic transition (Ar I, 750.4 nm) and an ionic transition (Ar II, 434.8 nm). The absolute scale of these optical emissions has been determined by comparison with the optical emission from a calibrated standard lamp. All measurements were made in a well-defined rf reactor. They provide detailed characterization of local time-resolved plasma conditions suitable for the comparison with results from other experiments and theoretical models. These measurements represent a new level of detail in diagnostic measurements of rf plasmas, and provide insight into the electron transport properties of rf discharges. PMID:28053464

  6. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  7. Utilization of coincidence criteria in absolute length measurements by optical interferometry in vacuum and air

    NASA Astrophysics Data System (ADS)

    Schödel, R.

    2015-08-01

    Traceability of length measurements to the international system of units (SI) can be realized by using optical interferometry making use of well-known frequencies of monochromatic light sources mentioned in the Mise en Pratique for the realization of the metre. At some national metrology institutes, such as Physikalisch-Technische Bundesanstalt (PTB) in Germany, the absolute length of prismatic bodies (e.g. gauge blocks) is realized by so-called gauge-block interference comparators. At PTB, a number of such imaging phase-stepping interference comparators exist, including specialized vacuum interference comparators, each equipped with three highly stabilized laser light sources. The length of a material measure is expressed as a multiple of each wavelength. The large number of integer interference orders can be extracted by the method of exact fractions in which the coincidence of the lengths resulting from the different wavelengths is utilized as a criterion. The unambiguous extraction of the integer interference orders is an essential prerequisite for correct length measurements. This paper critically discusses coincidence criteria and their validity for three modes of absolute length measurements: 1) measurements under vacuum in which the wavelengths can be identified with the vacuum wavelengths, 2) measurements under air in which the air refractive index is obtained from environmental parameters using an empirical equation, and 3) measurements under air in which the air refractive index is obtained interferometrically by utilizing a vacuum cell placed along the measurement pathway. For case 3), which corresponds to PTB’s Kösters-Comparator for long gauge blocks, the unambiguous determination of integer interference orders related to the air refractive index could be improved by about a factor of ten when an ‘overall dispersion value,’ suggested in this paper, is used as coincidence criterion.

  8. Dual-stage trapped-flux magnet cryostat for measurements at high magnetic fields

    DOEpatents

    Islam, Zahirul; Das, Ritesh K.; Weinstein, Roy

    2015-04-14

    A method and a dual-stage trapped-flux magnet cryostat apparatus are provided for implementing enhanced measurements at high magnetic fields. The dual-stage trapped-flux magnet cryostat system includes a trapped-flux magnet (TFM). A sample, for example, a single crystal, is adjustably positioned proximate to the surface of the TFM, using a translation stage such that the distance between the sample and the surface is selectively adjusted. A cryostat is provided with a first separate thermal stage provided for cooling the TFM and with a second separate thermal stage provided for cooling sample.

  9. A multi-site analysis of random error in tower-based measurements of carbon and energy fluxes

    Treesearch

    Andrew D. Richardson; David Y. Hollinger; George G. Burba; Kenneth J. Davis; Lawrence B. Flanagan; Gabriel G. Katul; J. William Munger; Daniel M. Ricciuto; Paul C. Stoy; Andrew E. Suyker; Shashi B. Verma; Steven C. Wofsy; Steven C. Wofsy

    2006-01-01

    Measured surface-atmosphere fluxes of energy (sensible heat, H, and latent heat, LE) and CO2 (FCO2) represent the ``true?? flux plus or minus potential random and systematic measurement errors. Here, we use data from seven sites in the AmeriFlux network, including five forested sites (two of which include ``tall tower?? instrumentation), one grassland site, and one...

  10. Absolute colorimetric characterization of a DSLR camera

    NASA Astrophysics Data System (ADS)

    Guarnera, Giuseppe Claudio; Bianco, Simone; Schettini, Raimondo

    2014-03-01

    A simple but effective technique for absolute colorimetric camera characterization is proposed. It offers a large dynamic range requiring just a single, off-the-shelf target and a commonly available controllable light source for the characterization. The characterization task is broken down in two modules, respectively devoted to absolute luminance estimation and to colorimetric characterization matrix estimation. The characterized camera can be effectively used as a tele-colorimeter, giving an absolute estimation of the XYZ data in cd=m2. The user is only required to vary the f - number of the camera lens or the exposure time t, to better exploit the sensor dynamic range. The estimated absolute tristimulus values closely match the values measured by a professional spectro-radiometer.

  11. Comparison of sea surface flux measured by instrumented aircraft and ship during SOFIA and SEMAPHORE experiments

    NASA Astrophysics Data System (ADS)

    Durand, Pierre; Dupuis, HéLèNe; Lambert, Dominique; BéNech, Bruno; Druilhet, Aimé; Katsaros, Kristina; Taylor, Peter K.; Weill, Alain

    1998-10-01

    Two major campaigns (Surface of the Oceans, Fluxes and Interactions with the Atmosphere (SOFIA) and Structure des Echanges Mer-Atmosphère, Propriétés des Hétérogénéités Océaniques: Recherche Expérimentale (SEMAPHORE)) devoted to the study of ocean-atmosphere interaction were conducted in 1992 and 1993, respectively, in the Azores region. Among the various platforms deployed, instrumented aircraft and ship allowed the measurement of the turbulent flux of sensible heat, latent heat, and momentum. From coordinated missions we can evaluate the sea surface fluxes from (1) bulk relations and mean measurements performed aboard the ship in the atmospheric surface layer and (2) turbulence measurements aboard aircraft, which allowed the flux profiles to be estimated through the whole atmospheric boundary layer and therefore to be extrapolated toward the sea surface level. Continuous ship fluxes were calculated with bulk coefficients deduced from inertial-dissipation measurements in the same experiments, whereas aircraft fluxes were calculated with eddy-correlation technique. We present a comparison between these two estimations. Although momentum flux agrees quite well, aircraft estimations of sensible and latent heat flux are lower than those of the ship. This result is surprising, since aircraft momentum flux estimates are often considered as much less accurate than scalar flux estimates. The various sources of errors on the aircraft and ship flux estimates are discussed. For sensible and latent heat flux, random errors on aircraft estimates, as well as variability of ship flux estimates, are lower than the discrepancy between the two platforms, whereas the momentum flux estimates cannot be considered as significantly different. Furthermore, the consequence of the high-pass filtering of the aircraft signals on the flux values is analyzed; it is weak at the lowest altitudes flown and cannot therefore explain the discrepancies between the two platforms but becomes

  12. Dependence of absolute photon flux on infrared absorbance alteration and surface roughness on photoresist polymers irradiated with vacuum ultraviolet photons emitted from HBr plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Takeuchi, Takuya; Ishikawa, Kenji; Hayashi, Toshio; Takeda, Keigo; Sekine, Makoto; Hori, Masaru

    2017-12-01

    The absolute fluxes of vacuum ultraviolet (VUV) photons emitted from HBr plasma were analyzed and the effects of VUV photons on a photoresist polymer in ArF-excimer-laser (193 nm) lithography were quantitatively investigated on the basis of the infrared spectra attributed to the C=O region. The spectral peak intensity assigned to the methacrylic acid (MAA) in the photoresist drastically decreased owing to the loss of this monomer caused by the irradiation of VUV photons at dosages below 16 × 1016 photons/cm2. X-ray photoelectron spectroscopy observation showed that the removed monomer moved to the surface and generated volatile products that induced a decrease in film thickness. As a consequence, the surface became rough during the early-stage irradiation at dosages lower than 16 × 1016 photons/cm2 owing to the monomer loss of MAA with volatile product formation and subsequent cross-linking reactions.

  13. Physics-Based Modeling and Measurement of High-Flux Condensation Heat Transfer

    DTIC Science & Technology

    2011-09-01

    TRANSFER (Contract No. N000140811139) by Prof. Issam Mudawar Sung-Min Kim Joseph Kim Boiling and Two-Phase Flow Laboratory School of...Final 01-10-2008 to 30-09-2011 Physics-Based Modeling and Measurement of High-Flux Condensation Heat Transfer NA N00014-08-1-1139 NA NA NA NA Mudawar ...respectively. phase change, condensation, electronics cooling, micro-channel, high-flux U U U UU 107 Mudawar , Issam 765-494-5705 Reset PHYSICS-BASED

  14. A highly accurate absolute gravimetric network for Albania, Kosovo and Montenegro

    NASA Astrophysics Data System (ADS)

    Ullrich, Christian; Ruess, Diethard; Butta, Hubert; Qirko, Kristaq; Pavicevic, Bozidar; Murat, Meha

    2016-04-01

    The objective of this project is to establish a basic gravity network in Albania, Kosovo and Montenegro to enable further investigations in geodetic and geophysical issues. Therefore the first time in history absolute gravity measurements were performed in these countries. The Norwegian mapping authority Kartverket is assisting the national mapping authorities in Kosovo (KCA) (Kosovo Cadastral Agency - Agjencia Kadastrale e Kosovës), Albania (ASIG) (Autoriteti Shtetëror i Informacionit Gjeohapësinor) and in Montenegro (REA) (Real Estate Administration of Montenegro - Uprava za nekretnine Crne Gore) in improving the geodetic frameworks. The gravity measurements are funded by Kartverket. The absolute gravimetric measurements were performed from BEV (Federal Office of Metrology and Surveying) with the absolute gravimeter FG5-242. As a national metrology institute (NMI) the Metrology Service of the BEV maintains the national standards for the realisation of the legal units of measurement and ensures their international equivalence and recognition. Laser and clock of the absolute gravimeter were calibrated before and after the measurements. The absolute gravimetric survey was carried out from September to October 2015. Finally all 8 scheduled stations were successfully measured: there are three stations located in Montenegro, two stations in Kosovo and three stations in Albania. The stations are distributed over the countries to establish a gravity network for each country. The vertical gradients were measured at all 8 stations with the relative gravimeter Scintrex CG5. The high class quality of some absolute gravity stations can be used for gravity monitoring activities in future. The measurement uncertainties of the absolute gravity measurements range around 2.5 micro Gal at all stations (1 microgal = 10-8 m/s2). In Montenegro the large gravity difference of 200 MilliGal between station Zabljak and Podgorica can be even used for calibration of relative gravimeters

  15. Untangling Autophagy Measurements: All Fluxed Up

    PubMed Central

    Gottlieb, Roberta A.; Andres, Allen M.; Sin, Jon; Taylor, David

    2015-01-01

    Autophagy is an important physiological process in the heart, and alterations in autophagic activity can exacerbate or mitigate injury during various pathological processes. Methods to assess autophagy have changed rapidly as the field of research has expanded. As with any new field, methods and standards for data analysis and interpretation evolve as investigators acquire experience and insight. The purpose of this review is to summarize current methods to measure autophagy, selective mitochondrial autophagy (mitophagy), and autophagic flux. We will examine several published studies where confusion arose in in data interpretation, in order to illustrate the challenges. Finally we will discuss methods to assess autophagy in vivo and in patients. PMID:25634973

  16. Optimization of magnetic flux density measurement using multiple RF receiver coils and multi-echo in MREIT.

    PubMed

    Jeong, Woo Chul; Chauhan, Munish; Sajib, Saurav Z K; Kim, Hyung Joong; Serša, Igor; Kwon, Oh In; Woo, Eung Je

    2014-09-07

    Magnetic Resonance Electrical Impedance Tomography (MREIT) is an MRI method that enables mapping of internal conductivity and/or current density via measurements of magnetic flux density signals. The MREIT measures only the z-component of the induced magnetic flux density B = (Bx, By, Bz) by external current injection. The measured noise of Bz complicates recovery of magnetic flux density maps, resulting in lower quality conductivity and current-density maps. We present a new method for more accurate measurement of the spatial gradient of the magnetic flux density gradient (∇ Bz). The method relies on the use of multiple radio-frequency receiver coils and an interleaved multi-echo pulse sequence that acquires multiple sampling points within each repetition time. The noise level of the measured magnetic flux density Bz depends on the decay rate of the signal magnitude, the injection current duration, and the coil sensitivity map. The proposed method uses three key steps. The first step is to determine a representative magnetic flux density gradient from multiple receiver coils by using a weighted combination and by denoising the measured noisy data. The second step is to optimize the magnetic flux density gradient by using multi-echo magnetic flux densities at each pixel in order to reduce the noise level of ∇ Bz and the third step is to remove a random noise component from the recovered ∇ Bz by solving an elliptic partial differential equation in a region of interest. Numerical simulation experiments using a cylindrical phantom model with included regions of low MRI signal to noise ('defects') verified the proposed method. Experimental results using a real phantom experiment, that included three different kinds of anomalies, demonstrated that the proposed method reduced the noise level of the measured magnetic flux density. The quality of the recovered conductivity maps using denoised ∇ Bz data showed that the proposed method reduced the conductivity

  17. Chamber and Diffusive Based Carbon Flux Measurements in an Alaskan Arctic Ecosystem

    NASA Astrophysics Data System (ADS)

    Wilkman, E.; Oechel, W. C.; Zona, D.

    2013-12-01

    Eric Wilkman, Walter Oechel, Donatella Zona Comprising an area of more than 7 x 106 km2 and containing over 11% of the world's organic matter pool, Arctic terrestrial ecosystems are vitally important components of the global carbon cycle, yet their structure and functioning are sensitive to subtle changes in climate and many of these functional changes can have large effects on the atmosphere and future climate regimes (Callaghan & Maxwell 1995, Chapin et al. 2002). Historically these northern ecosystems have acted as strong C sinks, sequestering large stores of atmospheric C due to photosynthetic dominance in the short summer season and low rates of decomposition throughout the rest of the year as a consequence of cold, nutrient poor, and generally water-logged conditions. Currently, much of this previously stored carbon is at risk of loss to the atmosphere due to accelerated soil organic matter decomposition in warmer future climates (Grogan & Chapin 2000). Although there have been numerous studies on Arctic carbon dynamics, much of the previous soil flux work has been done at limited time intervals, due to both the harshness of the environment and labor and time constraints. Therefore, in June of 2013 an Ultraportable Greenhouse Gas Analyzer (UGGA - Los Gatos Research Inc.) was deployed in concert with the LI-8100A Automated Soil Flux System (LI-COR Biosciences) in Barrow, AK to gather high temporal frequency soil CO2 and CH4 fluxes from a wet sedge tundra ecosystem. An additional UGGA in combination with diffusive probes, installed in the same location, provides year-round soil and snow CO2 and CH4 concentrations. When used in combination with the recently purchased AlphaGUARD portable radon monitor (Saphymo GmbH), continuous soil and snow diffusivities and fluxes of CO2 and CH4 can be calculated (Lehmann & Lehmann 2000). Of particular note, measuring soil gas concentration over a diffusive gradient in this way allows one to separate both net production and

  18. Renilla Luciferase-LC3 Based Reporter Assay for Measuring Autophagic Flux.

    PubMed

    Farkas, T; Jäättelä, M

    2017-01-01

    Macroautophagy (autophagy) is a dynamic intracellular degradation pathway. Monitoring the flux through the autophagy pathway is experimentally challenging but obviously a prerequisite for the proper investigation of the process. Here, we present an indirect autophagy flux assay based on monitoring the degradation of an autophagosome-associated fusion protein Rluc-LC3 by luminescence detection. The method is suitable for screening purposes with a high number of parallel samples and can be used for measurements in cell lysates as well as in living cells. The Rluc-LC3 assay has proven useful for the identification of genes, miRNAs, and small molecules that regulate autophagy flux in mammalian cells. © 2017 Elsevier Inc. All rights reserved.

  19. Microwave measurements of the absolute values of absorption by water vapour in the atmosphere.

    PubMed

    Hogg, D C; Guiraud, F O

    1979-05-31

    MEASUREMENT of the absolute value of absorption by water vapour at microwave frequencies is difficult because the effect is so small. Far in the wings of the absorption lines, in the so-called 'windows' of the spectrum, it is especially difficult to achieve high accuracy in the free atmosphere. But it is in these windows that the behaviour of the absorption is important from both applied and scientific points of view. Satellite communications, remote sensing of the atmosphere, and radioastronomy, are all influenced by this behaviour. Measurements on an Earth-space path are reported here; the results indicate a nonlinear relationship between absorption and water-vapour content.

  20. Measurement of absolute regional lung air volumes from near-field x-ray speckles.

    PubMed

    Leong, Andrew F T; Paganin, David M; Hooper, Stuart B; Siew, Melissa L; Kitchen, Marcus J

    2013-11-18

    Propagation-based phase contrast x-ray (PBX) imaging yields high contrast images of the lung where airways that overlap in projection coherently scatter the x-rays, giving rise to a speckled intensity due to interference effects. Our previous works have shown that total and regional changes in lung air volumes can be accurately measured from two-dimensional (2D) absorption or phase contrast images when the subject is immersed in a water-filled container. In this paper we demonstrate how the phase contrast speckle patterns can be used to directly measure absolute regional lung air volumes from 2D PBX images without the need for a water-filled container. We justify this technique analytically and via simulation using the transport-of-intensity equation and calibrate the technique using our existing methods for measuring lung air volume. Finally, we show the full capabilities of this technique for measuring regional differences in lung aeration.

  1. Cluster electric current density measurements within a magnetic flux rope in the plasma sheet

    NASA Technical Reports Server (NTRS)

    Slavin, J. A.; Lepping, R. P.; Gjerloev, J.; Goldstein, M. L.; Fairfield, D. H.; Acuna, M. H.; Balogh, A.; Dunlop, M.; Kivelson, M. G.; Khurana, K.

    2003-01-01

    On August 22, 2001 all 4 Cluster spacecraft nearly simultaneously penetrated a magnetic flux rope in the tail. The flux rope encounter took place in the central plasma sheet, Beta(sub i) approx. 1-2, near the leading edge of a bursty bulk flow. The "time-of-flight" of the flux rope across the 4 spacecraft yielded V(sub x) approx. 700 km/s and a diameter of approx.1 R(sub e). The speed at which the flux rope moved over the spacecraft is in close agreement with the Cluster plasma measurements. The magnetic field profiles measured at each spacecraft were first modeled separately using the Lepping-Burlaga force-free flux rope model. The results indicated that the center of the flux rope passed northward (above) s/c 3, but southward (below) of s/c 1, 2 and 4. The peak electric currents along the central axis of the flux rope predicted by these single-s/c models were approx.15-19 nA/sq m. The 4-spacecraft Cluster magnetic field measurements provide a second means to determine the electric current density without any assumption regarding flux rope structure. The current profile determined using the curlometer technique was qualitatively similar to those determined by modeling the individual spacecraft magnetic field observations and yielded a peak current density of 17 nA/m2 near the central axis of the rope. However, the curlometer results also showed that the flux rope was not force-free with the component of the current density perpendicular to the magnetic field exceeding the parallel component over the forward half of the rope, perhaps due to the pressure gradients generated by the collision of the BBF with the inner magnetosphere. Hence, while the single-spacecraft models are very successful in fitting flux rope magnetic field and current variations, they do not provide a stringent test of the force-free condition.

  2. Spatially resolved flux measurements of NOx from London suggest significantly higher emissions than predicted by inventories.

    PubMed

    Vaughan, Adam R; Lee, James D; Misztal, Pawel K; Metzger, Stefan; Shaw, Marvin D; Lewis, Alastair C; Purvis, Ruth M; Carslaw, David C; Goldstein, Allen H; Hewitt, C Nicholas; Davison, Brian; Beevers, Sean D; Karl, Thomas G

    2016-07-18

    To date, direct validation of city-wide emissions inventories for air pollutants has been difficult or impossible. However, recent technological innovations now allow direct measurement of pollutant fluxes from cities, for comparison with emissions inventories, which are themselves commonly used for prediction of current and future air quality and to help guide abatement strategies. Fluxes of NOx were measured using the eddy-covariance technique from an aircraft flying at low altitude over London. The highest fluxes were observed over central London, with lower fluxes measured in suburban areas. A footprint model was used to estimate the spatial area from which the measured emissions occurred. This allowed comparison of the flux measurements to the UK's National Atmospheric Emissions Inventory (NAEI) for NOx, with scaling factors used to account for the actual time of day, day of week and month of year of the measurement. The comparison suggests significant underestimation of NOx emissions in London by the NAEI, mainly due to its under-representation of real world road traffic emissions. A comparison was also carried out with an enhanced version of the inventory using real world driving emission factors and road measurement data taken from the London Atmospheric Emissions Inventory (LAEI). The measurement to inventory agreement was substantially improved using the enhanced version, showing the importance of fully accounting for road traffic, which is the dominant NOx emission source in London. In central London there was still an underestimation by the inventory of 30-40% compared with flux measurements, suggesting significant improvements are still required in the NOx emissions inventory.

  3. Design and measurement of improved capacitively-shunted flux qubits

    NASA Astrophysics Data System (ADS)

    Sears, Adam; Birenbaum, Jeffrey; Hover, David; Gudmundsen, Theodore; Kerman, Andrew; Welander, Paul; Yoder, Jonilyn L.; Gustavsson, Simon; Jin, Xiaoyue; Kamal, Archana; Clarke, John; Oliver, William

    2014-03-01

    The addition of a capacitive or inductive shunt across one of the junctions can alter the coherence properties of a classic flux or RF-SQUID qubit. We have studied the performance of capacitively shunted flux qubits fabricated with MBE aluminum, starting from a 2D coplanar waveguide geometry used in similar high-performance transmon qubits, and measured dispersively. We will detail the importance of design parameters that preserve the flux qubit's anharmonicity and discuss conclusions about materials quality based on calculations of the participation of junction, dielectric, and superconductor components. This research was funded in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA); and by the Assistant Secretary of Defense for Research & Engineering under Air Force Contract number FA8721-05-C-0002. All statements of fact, opinion or conclusions contained herein are those of the authors and should not be construed as representing the official views or policies of IARPA, the ODNI, or the U.S. Government Present address: SLAC National Accelerator Laboratory, Menlo Park, CA.

  4. Determination of solar proton fluxes and energies at high solar latitudes by UV radiation measurements

    NASA Technical Reports Server (NTRS)

    Witt, N.; Blum, P. W.; Ajello, J. M.

    1981-01-01

    The latitudinal variation of the solar proton flux and energy causes a density increase at high solar latitudes of the neutral gas penetrating the heliosphere. Measurements of the neutral density by UV resonance radiation observations from interplanetary spacecraft thus permit deductions on the dependence of the solar proton flux on heliographic latitude. Using both the results of Mariner 10 measurements and of other off-ecliptic solar wind observations, the values of the solar proton fluxes and energies at polar heliographic latitudes are determined for several cases of interest. The Mariner 10 analysis, together with IPS results, indicate a significant decrease of the solar proton flux at polar latitudes.

  5. Direct measurement of magnetic flux compression on the Z pulsed-power accelerator

    NASA Astrophysics Data System (ADS)

    McBride, R. D.; Bliss, D. E.; Martin, M. R.; Jennings, C. A.; Lamppa, D. C.; Dolan, D. H.; Lemke, R. W.; Rovang, D. C.; Rochau, G. A.; Cuneo, M. E.; Sinars, D. B.; Intrator, T. P.; Weber, T. E.

    2016-10-01

    We report on the progress made to date for directly measuring magnetic flux compression on Z. Each experiment consisted of an initially solid aluminum liner (a cylindrical tube), which was imploded using Z's drive current (0-20 MA in 100 ns). The imploding liner compresses a 10-20-T axial seed field, Bz(0), supplied by an independently driven Helmholtz coil pair. Assuming perfect flux conservation, the axial field amplification should be well described by Bz(t) =Bz (0)×[R(0)/R(t)]2, where R is the liner's inner surface radius. With perfect flux conservation, Bz and dBz/dt values exceeding 104 T and 1012 T/s, respectively, are expected. These large values, the diminishing liner volume, and the harsh environment on Z, make it particularly challenging to measure these fields directly. We report on our latest efforts to do so using a fiber-optic-based Faraday rotation diagnostic, where the magneto-active portion of the sensor is made from terbium-doped optical fiber. We have now used this diagnostic to measure a flux-compressed magnetic field to over 600 T prior to the imploding liner hitting the on-axis fiber housing. This project was funded in part by Sandia's LDRD program and US DOE-NNSA contract DE-AC04-94AL85000.

  6. New two-dimensional space-resolving flux detection technique for measurement of hohlraum inner radiation in Shenguang-III prototype.

    PubMed

    Ren, Kuan; Liu, Shenye; Du, Huabing; Hou, Lifei; Jing, Longfei; Zhao, Yang; Yang, Zhiwen; Wei, Minxi; Deng, Keli; Yao, Li; Yang, Guohong; Li, Sanwei; Lan, Ke; Liu, Jie; Zhu, Xiaoli; Ding, Yongkun; Yi, Lin

    2015-10-01

    The space-resolving measurement of X-ray flux from a specific area (laser spot, re-emitting wall, or capsule) inside the hohlraum is an ongoing and critical problem in indirectly driven inertial-confinement fusion experiments. In this work, we developed a new two-dimensional space-resolving flux detection technique to measure the X-ray flux from specific areas inside the hohlraum by using the time- and space-resolving flux detector (SRFD). In two typical hohlraum experiments conducted at the Shenguang-III prototype laser facility, the X-ray flux and radiation temperature from an area 0.2 mm in diameter inside the hohlraum were measured through the laser entrance hole (LEH). The different flux intensities and radiation temperatures detected using the SRFD from the inner area of the LEH were compared with the result measured using the flat-response X-ray detector from the entire LEH. This comparison was also analyzed theoretically. The inner area detected using the SRFD was found to be the re-emitting wall area alone. This important improvement in space-resolving X-ray flux measurement will enhance the current X-ray flux space characterization techniques, thereby furthering the quantitative understanding of X-ray flux space behavior in the hohlraum.

  7. New two-dimensional space-resolving flux detection technique for measurement of hohlraum inner radiation in Shenguang-III prototype

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ren, Kuan; Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900; Liu, Shenye, E-mail: lsye1029@163.com

    2015-10-15

    The space-resolving measurement of X-ray flux from a specific area (laser spot, re-emitting wall, or capsule) inside the hohlraum is an ongoing and critical problem in indirectly driven inertial-confinement fusion experiments. In this work, we developed a new two-dimensional space-resolving flux detection technique to measure the X-ray flux from specific areas inside the hohlraum by using the time- and space-resolving flux detector (SRFD). In two typical hohlraum experiments conducted at the Shenguang-III prototype laser facility, the X-ray flux and radiation temperature from an area 0.2 mm in diameter inside the hohlraum were measured through the laser entrance hole (LEH). Themore » different flux intensities and radiation temperatures detected using the SRFD from the inner area of the LEH were compared with the result measured using the flat-response X-ray detector from the entire LEH. This comparison was also analyzed theoretically. The inner area detected using the SRFD was found to be the re-emitting wall area alone. This important improvement in space-resolving X-ray flux measurement will enhance the current X-ray flux space characterization techniques, thereby furthering the quantitative understanding of X-ray flux space behavior in the hohlraum.« less

  8. Measurement of Urban fluxes of CO2 and water

    NASA Astrophysics Data System (ADS)

    Grimmond, S.; Crawford, B.; Offerle, B.; Hom, J.

    2006-05-01

    Measurements of surface-atmosphere fluxes of carbon dioxide (FCO2) and latent heat in urban environments are rare even though cities are a major source of atmospheric CO2 and users of water. In this paper, an overview of urban FCO2 measurements will be presented to illustrate how and where such measurements are being conducted and emerging results to date. Most of these studies have been conducted over short periods of time; few studies have considered annual sources/sinks. More investigations have been conducted, and are planned, in European cities than elsewhere, most commonly in areas of medium density urban development. The most dense urban sites are significant net sources of carbon. However, in areas where there is large amounts of vegetation present, there is a net sink of carbon during the summertime. In the second part of the presentation, more detailed attention will be directed to an ongoing measurement program in Baltimore, MD (part of the Baltimore Ecosystem Study). Eddy covariance instrumentation mounted on a tall-tower at 41.2 m has continuously measured local-scale fluxes of carbon dioxide from a suburban environment since 2001. Several features make this particular study unique: 1) for an urban area, the study site is extensively vegetated, 2) the period of record (2001-2005) is among the longest available for urban FCO2 measurements, 3) both closed-path and open-path infrared gas analyzers are used for observations, and 4) several unique data quality control and gap-filling methods have been developed for use in an urban environment. Additionally, detailed surface datasets and GIS software are used to perform flux source area analysis. Results from Baltimore indicate that FCO2 is very dependent on source area land-cover characteristics, particularly the proportion of vegetated and built surfaces. Over the course of a year, the urban surface is a strong net source of CO2, though there is considerable inter-annual variability depending on

  9. 3D-Printed Detector Band for Magnetic Off-Plane Flux Measurements in Laminated Machine Cores

    PubMed Central

    Pfützner, Helmut; Palkovits, Martin; Windischhofer, Andreas; Giefing, Markus

    2017-01-01

    Laminated soft magnetic cores of transformers, rotating machines etc. may exhibit complex 3D flux distributions with pronounced normal fluxes (off-plane fluxes), perpendicular to the plane of magnetization. As recent research activities have shown, detections of off-plane fluxes tend to be essential for the optimization of core performances aiming at a reduction of core losses and of audible noise. Conventional sensors for off-plane flux measurements tend to be either of high thickness, influencing the measured fluxes significantly, or require laborious preparations. In the current work, thin novel detector bands for effective and simple off-plane flux detections in laminated machine cores were manufactured. They are printed in an automatic way by an in-house developed 3D/2D assembler. The latter enables a unique combination of conductive and non-conductive materials. The detector bands were effectively tested in the interior of a two-package, three-phase model transformer core. They proved to be mechanically resilient, even for strong clamping of the core. PMID:29257063

  10. Fluxes of biogenic volatile organic compounds measured and modelled above a Norway spruce forest

    NASA Astrophysics Data System (ADS)

    Juráň, Stanislav; Fares, Silvano; Pallozzi, Emanuele; Guidolotti, Gabriele; Savi, Flavia; Alivernini, Alessandro; Calfapietra, Carlo; Večeřová, Kristýna; Křůmal, Kamil; Večeřa, Zbyněk; Cudlín, Pavel; Urban, Otmar

    2016-04-01

    Fluxes of biogenic volatile organic compounds (BVOCs) were investigated at Norway spruce forest at Bílý Kříž in Beskydy Mountains of the Czech Republic during the summer 2014. A proton-transfer-reaction-time-of-flight mass spectrometer (PTR-TOF-MS, Ionicon Analytik, Austria) has been coupled with eddy-covariance system. Additionally, Inverse Lagrangian Transport Model has been used to derive fluxes from concentration gradient of various monoterpenes previously absorbed into n-heptane by wet effluent diffusion denuder with consequent quantification by gas chromatography with mass spectrometry detection. Modelled data cover each one day of three years with different climatic conditions and previous precipitation patterns. Model MEGAN was run to cover all dataset with monoterpene fluxes and measured basal emission factor. Highest fluxes measured by eddy-covariance were recorded during the noon hours, represented particularly by monoterpenes and isoprene. Inverse Lagrangian Transport Model suggests most abundant monoterpene fluxes being α- and β-pinene. Principal component analysis revealed dependencies of individual monoterpene fluxes on air temperature and particularly global radiation; however, these dependencies were monoterpene specific. Relationships of monoterpene fluxes with CO2 flux and relative air humidity were found to be negative. MEGAN model correlated to eddy-covariance PTR-TOF-MS measurement evince particular differences, which will be shown and discussed. Bi-directional fluxes of oxygenated short-chain volatiles (methanol, formaldehyde, acetone, acetaldehyde, formic acid, acetic acid, methyl vinyl ketone, methacrolein, and methyl ethyl ketone) were recorded by PTR-TOF-MS. Volatiles of anthropogenic origin as benzene and toluene were likely transported from the most benzene polluted region in Europe - Ostrava city and adjacent part of Poland around Katowice, where metallurgical and coal mining industries are located. Those were accumulated during

  11. The absolute disparity anomaly and the mechanism of relative disparities.

    PubMed

    Chopin, Adrien; Levi, Dennis; Knill, David; Bavelier, Daphne

    2016-06-01

    There has been a long-standing debate about the mechanisms underlying the perception of stereoscopic depth and the computation of the relative disparities that it relies on. Relative disparities between visual objects could be computed in two ways: (a) using the difference in the object's absolute disparities (Hypothesis 1) or (b) using relative disparities based on the differences in the monocular separations between objects (Hypothesis 2). To differentiate between these hypotheses, we measured stereoscopic discrimination thresholds for lines with different absolute and relative disparities. Participants were asked to judge the depth of two lines presented at the same distance from the fixation plane (absolute disparity) or the depth between two lines presented at different distances (relative disparity). We used a single stimulus method involving a unique memory component for both conditions, and no extraneous references were available. We also measured vergence noise using Nonius lines. Stereo thresholds were substantially worse for absolute disparities than for relative disparities, and the difference could not be explained by vergence noise. We attribute this difference to an absence of conscious readout of absolute disparities, termed the absolute disparity anomaly. We further show that the pattern of correlations between vergence noise and absolute and relative disparity acuities can be explained jointly by the existence of the absolute disparity anomaly and by the assumption that relative disparity information is computed from absolute disparities (Hypothesis 1).

  12. The absolute disparity anomaly and the mechanism of relative disparities

    PubMed Central

    Chopin, Adrien; Levi, Dennis; Knill, David; Bavelier, Daphne

    2016-01-01

    There has been a long-standing debate about the mechanisms underlying the perception of stereoscopic depth and the computation of the relative disparities that it relies on. Relative disparities between visual objects could be computed in two ways: (a) using the difference in the object's absolute disparities (Hypothesis 1) or (b) using relative disparities based on the differences in the monocular separations between objects (Hypothesis 2). To differentiate between these hypotheses, we measured stereoscopic discrimination thresholds for lines with different absolute and relative disparities. Participants were asked to judge the depth of two lines presented at the same distance from the fixation plane (absolute disparity) or the depth between two lines presented at different distances (relative disparity). We used a single stimulus method involving a unique memory component for both conditions, and no extraneous references were available. We also measured vergence noise using Nonius lines. Stereo thresholds were substantially worse for absolute disparities than for relative disparities, and the difference could not be explained by vergence noise. We attribute this difference to an absence of conscious readout of absolute disparities, termed the absolute disparity anomaly. We further show that the pattern of correlations between vergence noise and absolute and relative disparity acuities can be explained jointly by the existence of the absolute disparity anomaly and by the assumption that relative disparity information is computed from absolute disparities (Hypothesis 1). PMID:27248566

  13. Calibration of High Heat Flux Sensors at NIST

    PubMed Central

    Murthy, A. V.; Tsai, B. K.; Gibson, C. E.

    1997-01-01

    An ongoing program at the National Institute of Standards and Technology (NIST) is aimed at improving and standardizing heat-flux sensor calibration methods. The current calibration needs of U.S. science and industry exceed the current NIST capability of 40 kW/m2 irradiance. In achieving this goal, as well as meeting lower-level non-radiative heat flux calibration needs of science and industry, three different types of calibration facilities currently are under development at NIST: convection, conduction, and radiation. This paper describes the research activities associated with the NIST Radiation Calibration Facility. Two different techniques, transfer and absolute, are presented. The transfer calibration technique employs a transfer standard calibrated with reference to a radiometric standard for calibrating the sensors using a graphite tube blackbody. Plans for an absolute calibration facility include the use of a spherical blackbody and a cooled aperture and sensor-housing assembly to calibrate the sensors in a low convective environment. PMID:27805156

  14. Concentrated solar-flux measurements at the IEA-SSPS solar-central-receiver power plant, Tabernas - Lameria (Spain)

    NASA Astrophysics Data System (ADS)

    Vontobel, G.; Schelders, C.; Real, M.

    A flux analyzing system (F.A.S.) was installed at the central receiver system of the SSPS project to determine the relative flux distribution of the heliostat field and to measure the entire optical solar flux reflected from the heliostat field into the receiver cavity. The functional principles of the F.A.S. are described. The raw data and the evaluation of the measurements of the entire helistat field are given, and an approach to determine the actual fluxes which hit the receiver tube bundle is presented. A method is described to qualify the performance of each heliostat using a computer code. The data of the measurements of the direct radiation are presented.

  15. On the discrepancy between eddy covariance and lysimetry-based surface flux measurements under strongly advective conditions

    NASA Astrophysics Data System (ADS)

    Alfieri, Joseph G.; Kustas, William P.; Prueger, John H.; Hipps, Lawrence E.; Evett, Steven R.; Basara, Jeffrey B.; Neale, Christopher M. U.; French, Andrew N.; Colaizzi, Paul; Agam, Nurit; Cosh, Michael H.; Chavez, José L.; Howell, Terry A.

    2012-12-01

    Discrepancies can arise among surface flux measurements collected using disparate techniques due to differences in both the instrumentation and theoretical underpinnings of the different measurement methods. Using data collected primarily within a pair of irrigated cotton fields as a part of the 2008 Bushland Evapotranspiration and Remote Sensing Experiment (BEAREX08), flux measurements collected with two commonly-used methods, eddy covariance (EC) and lysimetry (LY), were compared and substantial differences were found. Daytime mean differences in the flux measurements from the two techniques could be in excess of 200 W m-2 under strongly advective conditions. Three causes for this disparity were found: (i) the failure of the eddy covariance systems to fully balance the surface energy budget, (ii) flux divergence due to the local advection of warm, dry air over the irrigated cotton fields, and (iii) the failure of lysimeters to accurately represent the surface properties of the cotton fields as a whole. Regardless of the underlying cause, the discrepancy among the flux measurements underscores the difficulty in collecting these measurements under strongly advective conditions. It also raises awareness of the uncertainty associated with in situ micrometeorological measurements and the need for caution when using such data for model validation or as observational evidence to definitively support or refute scientific hypotheses.

  16. Absolute measurements of fast neutrons using yttrium.

    PubMed

    Roshan, M V; Springham, S V; Rawat, R S; Lee, P; Krishnan, M

    2010-08-01

    Yttrium is presented as an absolute neutron detector for pulsed neutron sources. It has high sensitivity for detecting fast neutrons. Yttrium has the property of generating a monoenergetic secondary radiation in the form of a 909 keV gamma-ray caused by inelastic neutron interaction. It was calibrated numerically using MCNPX and does not need periodic recalibration. The total yttrium efficiency for detecting 2.45 MeV neutrons was determined to be f(n) approximately 4.1x10(-4) with an uncertainty of about 0.27%. The yttrium detector was employed in the NX2 plasma focus experiments and showed the neutron yield of the order of 10(8) neutrons per discharge.

  17. Absolute equation of state measurements up to a gigbar using a converging shock

    NASA Astrophysics Data System (ADS)

    Kostinski, Natalie; Swift, Damian; Kritcher, Andrea; Lazicki, Amy; Hawreliak, James; Doeppner, Tilo; Saunders, Alison; Bachmann, Benjamin; Collins, Gilbert; Falcone, Roger; Nilsen, Joseph

    2017-10-01

    We are developing laser-driven loading platforms that allow the equation of state (EOS) of matter to be measured to pressures above 10 TPa on the Omega laser and 80 TPa at the National Ignition Facility respectively. These pressures are reached using a spherically-converging shock, with x-ray radiography as the primary diagnostic, enabling absolute EOS measurements to be made. At pressures above 10 TPa, the x-ray opacity drops significantly because of k-shell ionization. Superficially, this would prevent the compression from being measured, but radiographic marker layers can be used to constrain the reconstructed object and enable the opacity and compression to be determined simultaneously. Using these techniques, we have measured the Hugoniot EOS of polystyrene, diamond, and boron to over 50 TPa respectively, enabling their use as reference materials for relative measurements of materials more opaque to x-rays. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  18. A simple condition for uniqueness of the absolutely continuous ergodic measure and its application to economic models

    NASA Astrophysics Data System (ADS)

    Sato, Kenji; Yano, Makoto

    2012-09-01

    Unique existence of the absolutely continuous ergodic measure, or existence of ergodic chaos (in a strong sense), has been considered important in economics since it explains the mechanism underlying economic fluctuations. In the present study, a simple sufficient condition for ergodic chaos is proved and applied to economic models.

  19. Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling

    NASA Technical Reports Server (NTRS)

    Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.

    2011-01-01

    Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.

  20. Ultraviolet photometry from the Orbiting Astronomical Observatory. XXI - Absolute energy distribution of stars in the ultraviolet

    NASA Technical Reports Server (NTRS)

    Bless, R. C.; Code, A. D.; Fairchild, E. T.

    1976-01-01

    The absolute energy distribution in the ultraviolet is given for the stars alpha Vir, eta UMa, and alpha Leo. The calibration is based on absolute heterochromatic photometry between 2920 and 1370 A carried out with an Aerobee sounding rocket. The fundamental radiation standard is the synchrotron radiation from 240-MeV electrons in a certain synchrotron storage ring. On the basis of the sounding-rocket calibration, the preliminary OAO-2 spectrometer calibration has been revised; the fluxes for the three program stars are tabulated in energy per second per square centimeter per unit wavelength interval.

  1. Toward relaxed eddy accumulation measurements of sediment-water exchange in aquatic ecosystems

    NASA Astrophysics Data System (ADS)

    Lemaire, Bruno J.; Noss, Christian; Lorke, Andreas

    2017-09-01

    Solute transport across the sediment-water interface has major implications for water quality and biogeochemical cycling in aquatic ecosystems. Existing measurement techniques, however, are not capable of resolving sediment-water fluxes of most constituents under in situ flow conditions. We investigated whether relaxed eddy accumulation (REA), a micrometeorological technique with conditional sampling of turbulent updrafts and downdrafts, can be adapted to the aquatic environment. We simulated REA fluxes by reanalyzing eddy covariance measurements from a riverine lake. We found that the empirical coefficient that relates mass fluxes to the concentration difference between both REA samples is invariant with scalar and flow and responds as predicted by a joint Gaussian distribution of linearly correlated variables. Simulated REA fluxes differed on average by around 30% from eddy covariance fluxes (mean absolute error). Assessment of the lower quantification limit suggests that REA can potentially be applied for measuring benthic fluxes of a new range of constituents that cannot be assessed by standard eddy covariance methods.

  2. Measuring and modeling near surface reflected and emitted radiation fluxes at the FIFE site

    NASA Technical Reports Server (NTRS)

    Blad, Blaine L.; Norman, John M.; Walter-Shea, Elizabeth; Starks, Patrick; Vining, Roel; Hays, Cynthia

    1988-01-01

    Research was conducted during the four Intensive Field Campaigns (IFC) of the FIFE project in 1987. The research was done on a tall grass prairie with specific measurement sites on and near the Konza Prairie in Kansas. Measurements were made to help meet the following objectives: determination of the variability in reflected and emitted radiation fluxes in selected spectral wavebands as a function of topography and vegetative community; development of techniques to account for slope and sun angle effects on the radiation fluxes; estimation of shortwave albedo and net radiation fluxes using the reflected and emitted spectral measurements described; estimation of leaf and canopy spectral properties from calculated normalized differences coupled with off-nadir measurements using inversion techniques; estimation of plant water status at several locations with indices utilizing plant temperature and other environmental parameters; and determination of relationships between estimated plant water status and measured soil water content. Results are discussed.

  3. Electronic Absolute Cartesian Autocollimator

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.

    2006-01-01

    An electronic absolute Cartesian autocollimator performs the same basic optical function as does a conventional all-optical or a conventional electronic autocollimator but differs in the nature of its optical target and the manner in which the position of the image of the target is measured. The term absolute in the name of this apparatus reflects the nature of the position measurement, which, unlike in a conventional electronic autocollimator, is based absolutely on the position of the image rather than on an assumed proportionality between the position and the levels of processed analog electronic signals. The term Cartesian in the name of this apparatus reflects the nature of its optical target. Figure 1 depicts the electronic functional blocks of an electronic absolute Cartesian autocollimator along with its basic optical layout, which is the same as that of a conventional autocollimator. Referring first to the optical layout and functions only, this or any autocollimator is used to measure the compound angular deviation of a flat datum mirror with respect to the optical axis of the autocollimator itself. The optical components include an illuminated target, a beam splitter, an objective or collimating lens, and a viewer or detector (described in more detail below) at a viewing plane. The target and the viewing planes are focal planes of the lens. Target light reflected by the datum mirror is imaged on the viewing plane at unit magnification by the collimating lens. If the normal to the datum mirror is parallel to the optical axis of the autocollimator, then the target image is centered on the viewing plane. Any angular deviation of the normal from the optical axis manifests itself as a lateral displacement of the target image from the center. The magnitude of the displacement is proportional to the focal length and to the magnitude (assumed to be small) of the angular deviation. The direction of the displacement is perpendicular to the axis about which the

  4. Leonid Storm Flux Analysis From One Leonid MAC Video AL50R

    NASA Technical Reports Server (NTRS)

    Gural, Peter S.; Jenniskens, Peter; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    A detailed meteor flux analysis is presented of a seventeen-minute portion of one videotape, collected on November 18, 1999, during the Leonid Multi-instrument Aircraft Campaign. The data was recorded around the peak of the Leonid meteor storm using an intensified CCD camera pointed towards the low southern horizon. Positions of meteors on the sky were measured. These measured meteor distributions were compared to a Monte Carlo simulation, which is a new approach to parameter estimation for mass ratio and flux. Comparison of simulated flux versus observed flux levels, seen between 1:50:00 and 2:06:41 UT, indicate a magnitude population index of r = 1.8 +/- 0.1 and mass ratio of s = 1.64 +/- 0.06. The average spatial density of the material contributing to the Leonid storm peak is measured at 0.82 +/- 0.19 particles per square kilometer per hour for particles of at least absolute visual magnitude +6.5. Clustering analysis of the arrival times of Leonids impacting the earth's atmosphere over the total observing interval shows no enhancement or clumping down to time scales of the video frame rate. This indicates a uniformly random temporal distribution of particles in the stream encountered during the 1999 epoch. Based on the observed distribution of meteors on the sky and the model distribution, recommendations am made for the optimal pointing directions for video camera meteor counts during future ground and airborne missions.

  5. Surface energy fluxes on four slope sites during FIFE 1988

    NASA Technical Reports Server (NTRS)

    Nie, D.; Demetriades-Shah, T.; Kanemasu, E. T.

    1992-01-01

    Four slopes (facing north, south, east, and west) in the Konza Prairie Research Natural Area were selected to study the effect of topography on surface energy balance and other micrometeorological variables. Energy fluxes, air temperature, and vapor pressure were measured on the slopes throughout the 1988 growing season. Net radiation was highest on the south facing slope and lowest on the north facing slope, and the difference was more than 150 W/sq m (20-30 percent) at solar noon. For daily averages the difference was about 25 W/sq m (15 percent) early in the season and increased to about 60 W/sq m (30-50 percent) in September. Soil heat fluxes were similar for all the slopes. The absolute values of sensible heat flux were consistently lower on the north facing slope compared with other slopes. The south facing slope had the greatest day-to-day fluctuation in latent heat flux as a result of the interaction of net radiation, soil moisture, and green leaf area. Differences were found in the partitioning of the available energy among the slopes, and the north facing slope had a higher percentage of energy dissipated into latent heat flux. The north facing slope had higher air temperatures during the day and higher vapor pressures both during the day and at night when the wind was from the south.

  6. Interpretation of surface flux measurements in heterogeneous terrain during the Monsoon '90 experiment

    USGS Publications Warehouse

    Stannard, D.I.; Blanford, J.H.; Kustas, William P.; Nichols, W.D.; Amer, S.A.; Schmugge, T.J.; Weltz, M.A.

    1994-01-01

    A network of 9-m-tall surface flux measurement stations were deployed at eight sparsely vegetated sites during the Monsoon '90 experiment to measure net radiation, Q, soil heat flux, G, sensible heat flux, H (using eddy correlation), and latent heat flux, λE (using the energy balance equation). At four of these sites, 2-m-tall eddy correlation systems were used to measure all four fluxes directly. Also a 2-m-tall Bowen ratio system was deployed at one site. Magnitudes of the energy balance closure (Q + G + H + λE) increased as the complexity of terrain increased. The daytime Bowen ratio decreased from about 10 before the monsoon season to about 0.3 during the monsoons. Source areas of the measurements are developed and compared to scales of heterogeneity arising from the sparse vegetation and the topography. There was very good agreement among simultaneous measurements of Q with the same model sensor at different heights (representing different source areas), but poor agreement among different brands of sensors. Comparisons of simultaneous measurements of G suggest that because of the extremely small source area, extreme care in sensor deployment is necessary for accurate measurement in sparse canopies. A recently published model to estimate fetch is used to interpret measurements of H at the 2 m and 9 m heights. Three sites were characterized by undulating topography, with ridgetops separated by about 200–600 m. At these sites, sensors were located on ridgetops, and the 9-m fetch included the adjacent valley, whereas the 2-m fetch was limited to the immediate ridgetop and hillside. Before the monsoons began, vegetation was mostly dormant, the watershed was uniformly hot and dry, and the two measurements of H were in close agreement. After the monsoons began and vegetation fully matured, the 2-m measurements of H were significantly greater than the 9-m measurements, presumably because the vegetation in the valleys was denser and cooler than on the ridgetops and

  7. Constraining surface carbon fluxes using in situ measurements of carbonyl sulfide and carbon dioxide

    NASA Astrophysics Data System (ADS)

    Berkelhammer, M.; Asaf, D.; Still, C.; Montzka, S.; Noone, D.; Gupta, M.; Provencal, R.; Chen, H.; Yakir, D.

    2014-02-01

    Understanding the processes that control the terrestrial exchange of carbon is critical for assessing atmospheric CO2 budgets. Carbonyl sulfide (COS) is taken up by vegetation during photosynthesis following a pathway that mirrors CO2 but has a small or nonexistent emission component, providing a possible tracer for gross primary production. Field measurements of COS and CO2 mixing ratios were made in forest, senescent grassland, and riparian ecosystems using a laser absorption spectrometer installed in a mobile trailer. Measurements of leaf fluxes with a branch-bag gas-exchange system were made across species from 10 genera of trees, and soil fluxes were measured with a flow-through chamber. These data show (1) the existence of a narrow normalized daytime uptake ratio of COS to CO2 across vascular plant species of 1.7, providing critical information for the application of COS to estimate photosynthetic CO2 fluxes and (2) a temperature-dependent normalized uptake ratio of COS to CO2 from soils. Significant nighttime uptake of COS was observed in broad-leafed species and revealed active stomatal opening prior to sunrise. Continuous high-resolution joint measurements of COS and CO2 concentrations in the boundary layer are used here alongside the flux measurements to partition the influence that leaf and soil fluxes and entrainment of air from above have on the surface carbon budget. The results provide a number of critical constraints on the processes that control surface COS exchange, which can be used to diagnose the robustness of global models that are beginning to use COS to constrain terrestrial carbon exchange.

  8. Understanding the representativeness of FLUXNET for upscaling carbon flux from eddy covariance measurements

    DOE PAGES

    Kumar, Jitendra; Hoffman, Forrest M.; Hargrove, William W.; ...

    2016-08-23

    Eddy covariance data from regional flux networks are direct in situ measurement of carbon, water, and energy fluxes and are of vital importance for understanding the spatio-temporal dynamics of the the global carbon cycle. FLUXNET links regional networks of eddy covariance sites across the globe to quantify the spatial and temporal variability of fluxes at regional to global scales and to detect emergent ecosystem properties. This study presents an assessment of the representativeness of FLUXNET based on the recently released FLUXNET2015 data set. We present a detailed high resolution analysis of the evolving representativeness of FLUXNET through time. Results providemore » quantitative insights into the extent that various biomes are sampled by the network of networks, the role of the spatial distribution of the sites on the network scale representativeness at any given time, and how that representativeness has changed through time due to changing operational status and data availability at sites in the network. To realize the full potential of FLUXNET observations for understanding emergent ecosystem properties at regional and global scales, we present an approach for upscaling eddy covariance measurements. Informed by the representativeness of observations at the flux sites in the network, the upscaled data reflects the spatio-temporal dynamics of the carbon cycle captured by the in situ measurements. In conclusion, this study presents a method for optimal use of the rich point measurements from FLUXNET to derive an understanding of upscaled carbon fluxes, which can be routinely updated as new data become available, and direct network expansion by identifying regions poorly sampled by the current network.« less

  9. Wind tunnel measurements of pollutant turbulent fluxes in urban intersections

    NASA Astrophysics Data System (ADS)

    Carpentieri, Matteo; Hayden, Paul; Robins, Alan G.

    2012-01-01

    Wind tunnel experiments have been carried out at the EnFlo laboratory to measure mean and turbulent tracer fluxes in geometries of real street canyon intersections. The work was part of the major DAPPLE project, focussing on the area surrounding the intersection between Marylebone Road and Gloucester Place in Central London, UK. Understanding flow and dispersion in urban streets is a very important issue for air quality management and planning, and turbulent mass exchange processes are important phenomena that are very often neglected in urban modelling studies. The adopted methodology involved the combined use of laser Doppler anemometry and tracer concentration measurements. This methodology was applied to quantify the mean and turbulent flow and dispersion fields within several street canyon intersections. Vertical profiles of turbulent tracer flux were also measured. The technique, despite a number of limitations, proved reliable and allowed tracer balance calculations to be undertaken in the selected street canyon intersections. The experience gained in this work will enable much more precise studies in the future as issues affecting the accuracy of the experimental technique have been identified and resolved.

  10. Absolute radiometric calibration of advanced remote sensing systems

    NASA Technical Reports Server (NTRS)

    Slater, P. N.

    1982-01-01

    The distinction between the uses of relative and absolute spectroradiometric calibration of remote sensing systems is discussed. The advantages of detector-based absolute calibration are described, and the categories of relative and absolute system calibrations are listed. The limitations and problems associated with three common methods used for the absolute calibration of remote sensing systems are addressed. Two methods are proposed for the in-flight absolute calibration of advanced multispectral linear array systems. One makes use of a sun-illuminated panel in front of the sensor, the radiance of which is monitored by a spectrally flat pyroelectric radiometer. The other uses a large, uniform, high-radiance reference ground surface. The ground and atmospheric measurements required as input to a radiative transfer program to predict the radiance level at the entrance pupil of the orbital sensor are discussed, and the ground instrumentation is described.

  11. Double-sideband frequency scanning interferometry for long-distance dynamic absolute measurement

    NASA Astrophysics Data System (ADS)

    Mo, Di; Wang, Ran; Li, Guang-zuo; Wang, Ning; Zhang, Ke-shu; Wu, Yi-rong

    2017-11-01

    Absolute distance measurements can be achieved by frequency scanning interferometry which uses a tunable laser. The main drawback of this method is that it is extremely sensitive to the movement of targets. In addition, since this method is limited to the linearity of frequency scanning, it is commonly used for close measurements within tens of meters. In order to solve these problems, a double-sideband frequency scanning interferometry system is presented in the paper. It generates two opposite frequency scanning signals through a fixed frequency laser and a Mach-Zehnder modulator. And the system distinguishes the two interference fringe patterns corresponding to the two signals by IQ demodulation (i.e., quadrature detection) of the echo. According to the principle of double-sideband modulation, the two signals have the same characteristics. Therefore, the error caused by the target movement can be effectively eliminated, which is similar to dual-laser frequency scanned interferometry. In addition, this method avoids the contradiction between laser frequency stability and swept performance. The system can be applied to measure the distance of the order of kilometers, which profits from the good linearity of frequency scanning. In the experiment, a precision about 3 μm was achieved for a kilometer-level distance.

  12. Tall tower landscape scale N2O flux measurements in a Danish agricultural and urban, coastal area

    NASA Astrophysics Data System (ADS)

    Ibrom, Andreas; Lequy, Émeline; Loubet, Benjamin; Pilegaard, Kim; Ambus, Per

    2015-04-01

    Both technical and natural processes emit the greenhouse gas nitrous oxide (N2O) into the atmosphere. The abundant use of nitrogen (N) as fertiliser increases the concentration of reactive nitrogen (Nr) in the atmosphere, the hydrosphere and in the biosphere, i.e. in terrestrial and aquatic ecosystems. Surplus Nr is distributed across linkages to other spheres until most of it is emitted to the atmosphere as NO, N2O or N2. A complete estimate of the effects from human activities on N2O emissions must therefore include all emissions, the direct emissions and the indirect emissions that happen in interlinked spheres. For this it is necessary to assess the fluxes at least at the landscape scale. The episodic nature and the large spatial variability make it difficult to estimate the direct and indirect emissions in a landscape. Modelling requires not only to include the highly variable microbial processes in the ecosystems that produce N2O but as well the accurate simulation of lateral Nr fluxes and their effects on N2O fluxes in places remote from the primary Nr sources. In this context tall tower N2O flux measurements are particularly useful as they integrate over larger areas and can be run, continuously without disturbing the fluxes. On the other hand these measurements can be difficult to interpret due to difficulties to measure the small concentration fluctuations in the atmosphere at small flux rates and to accurately attribute the measured flux at the tower to the area that generates the flux, i.e. the source area. The Technical University of Denmark (DTU) has established eddy covariance N2O flux measurements on a 125 m tall tower at its Risø Campus as part of the EU research infrastructure project the 'Integrated non-CO2 Greenhouse gas Observing System' (InGOS). The eddy covariance system consisted of a N2O/CO quantum cascade laser, Los Gatos, Mountain View, CA, USA and a 3D sonic anemometer (USA-1), Metek, Elmshorn, Germany. The Risø peninsula lies at the

  13. Absolute measurement of cerebral optical coefficients, hemoglobin concentration and oxygen saturation in old and young adults with near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Hallacoglu, Bertan; Sassaroli, Angelo; Wysocki, Michael; Guerrero-Berroa, Elizabeth; Schnaider Beeri, Michal; Haroutunian, Vahram; Shaul, Merav; Rosenberg, Irwin H.; Troen, Aron M.; Fantini, Sergio

    2012-08-01

    We present near-infrared spectroscopy measurement of absolute cerebral hemoglobin concentration and saturation in a large sample of 36 healthy elderly (mean age, 85±6 years) and 19 young adults (mean age, 28±4 years). Non-invasive measurements were obtained on the forehead using a commercially available multi-distance frequency-domain system and analyzed using a diffusion theory model for a semi-infinite, homogeneous medium with semi-infinite boundary conditions. Our study included repeat measurements, taken five months apart, on 16 elderly volunteers that demonstrate intra-subject reproducibility of the absolute measurements with cross-correlation coefficients of 0.9 for absorption coefficient (μa), oxy-hemoglobin concentration ([HbO2]), and total hemoglobin concentration ([HbT]), 0.7 for deoxy-hemoglobin concentration ([Hb]), 0.8 for hemoglobin oxygen saturation (StO2), and 0.7 for reduced scattering coefficient (). We found significant differences between the two age groups. Compared to young subjects, elderly subjects had lower cerebral [HbO2], [Hb], [HbT], and StO2 by 10±4 μM, 4±3 μM, 14±5 μM, and 6%±5%, respectively. Our results demonstrate the reliability and robustness of multi-distance near-infrared spectroscopy measurements based on a homogeneous model in the human forehead on a large sample of human subjects. Absolute, non-invasive optical measurements on the brain, such as those presented here, can significantly advance the development of NIRS technology as a tool for monitoring resting/basal cerebral perfusion, hemodynamics, oxygenation, and metabolism.

  14. Absolute measurement of cerebral optical coefficients, hemoglobin concentration and oxygen saturation in old and young adults with near-infrared spectroscopy.

    PubMed

    Hallacoglu, Bertan; Sassaroli, Angelo; Wysocki, Michael; Guerrero-Berroa, Elizabeth; Schnaider Beeri, Michal; Haroutunian, Vahram; Shaul, Merav; Rosenberg, Irwin H; Troen, Aron M; Fantini, Sergio

    2012-08-01

    We present near-infrared spectroscopy measurement of absolute cerebral hemoglobin concentration and saturation in a large sample of 36 healthy elderly (mean age, 85 ± 6 years) and 19 young adults (mean age, 28 ± 4 years). Non-invasive measurements were obtained on the forehead using a commercially available multi-distance frequency-domain system and analyzed using a diffusion theory model for a semi-infinite, homogeneous medium with semi-infinite boundary conditions. Our study included repeat measurements, taken five months apart, on 16 elderly volunteers that demonstrate intra-subject reproducibility of the absolute measurements with cross-correlation coefficients of 0.9 for absorption coefficient (μa), oxy-hemoglobin concentration ([HbO2]), and total hemoglobin concentration ([HbT]), 0.7 for deoxy-hemoglobin concentration ([Hb]), 0.8 for hemoglobin oxygen saturation (StO2), and 0.7 for reduced scattering coefficient (μ's). We found significant differences between the two age groups. Compared to young subjects, elderly subjects had lower cerebral [HbO2], [Hb], [HbT], and StO2 by 10 ± 4 μM, 4 ± 3 μM, 14 ± 5 μM, and 6%±5%, respectively. Our results demonstrate the reliability and robustness of multi-distance near-infrared spectroscopy measurements based on a homogeneous model in the human forehead on a large sample of human subjects. Absolute, non-invasive optical measurements on the brain, such as those presented here, can significantly advance the development of NIRS technology as a tool for monitoring resting/basal cerebral perfusion, hemodynamics, oxygenation, and metabolism.

  15. Improved measurement of the reactor antineutrino flux and spectrum at Daya Bay

    NASA Astrophysics Data System (ADS)

    An, F. P.; Balantekin, A. B.; Band, H. R.; Bishai, M.; Blyth, S.; Cao, D.; Cao, G. F.; Cao, J.; Cen, W. R.; Chan, Y. L.; Chang, J. F.; Chang, L. C.; Chang, Y.; Chen, H. S.; Chen, Q. Y.; Chen, S. M.; Chen, Y. X.; Chen, Y.; Cheng, J.-H.; Cheng, J.; Cheng, Y. P.; Cheng, Z. K.; Cherwinka, J. J.; Chu, M. C.; Chukanov, A.; Cummings, J. P.; de Arcos, J.; Deng, Z. Y.; Ding, X. F.; Ding, Y. Y.; Diwan, M. V.; Dolgareva, M.; Dove, J.; Dwyer, D. A.; Edwards, W. R.; Gill, R.; Gonchar, M.; Gong, G. H.; Gong, H.; Grassi, M.; Gu, W. Q.; Guan, M. Y.; Guo, L.; Guo, R. P.; Guo, X. H.; Guo, Z.; Hackenburg, R. W.; Han, R.; Hans, S.; He, M.; Heeger, K. M.; Heng, Y. K.; Higuera, A.; Hor, Y. K.; Hsiung, Y. B.; Hu, B. Z.; Hu, T.; Hu, W.; Huang, E. C.; Huang, H. X.; Huang, X. T.; Huber, P.; Huo, W.; Hussain, G.; Jaffe, D. E.; Jaffke, P.; Jen, K. L.; Jetter, S.; Ji, X. P.; Ji, X. L.; Jiao, J. B.; Johnson, R. A.; Jones, D.; Joshi, J.; Kang, L.; Kettell, S. H.; Kohn, S.; Kramer, M.; Kwan, K. K.; Kwok, M. W.; Kwok, T.; Langford, T. J.; Lau, K.; Lebanowski, L.; Lee, J.; Lee, J. H. C.; Lei, R. T.; Leitner, R.; Li, C.; Li, D. J.; Li, F.; Li, G. S.; Li, Q. J.; Li, S.; Li, S. C.; Li, W. D.; Li, X. N.; Li, Y. F.; Li, Z. B.; Liang, H.; Lin, C. J.; Lin, G. L.; Lin, S.; Lin, S. K.; Lin, Y.-C.; Ling, J. J.; Link, J. M.; Littenberg, L.; Littlejohn, B. R.; Liu, D. W.; Liu, J. L.; Liu, J. C.; Loh, C. W.; Lu, C.; Lu, H. Q.; Lu, J. S.; Luk, K. B.; Lv, Z.; Ma, Q. M.; Ma, X. Y.; Ma, X. B.; Ma, Y. Q.; Malyshkin, Y.; Martinez Caicedo, D. A.; McDonald, K. T.; McKeown, R. D.; Mitchell, I.; Mooney, M.; Nakajima, Y.; Napolitano, J.; Naumov, D.; Naumova, E.; Ngai, H. Y.; Ning, Z.; Ochoa-Ricoux, J. P.; Olshevskiy, A.; Pan, H.-R.; Park, J.; Patton, S.; Pec, V.; Peng, J. C.; Pinsky, L.; Pun, C. S. J.; Qi, F. Z.; Qi, M.; Qian, X.; Raper, N.; Ren, J.; Rosero, R.; Roskovec, B.; Ruan, X. C.; Steiner, H.; Sun, G. X.; Sun, J. L.; Tang, W.; Taychenachev, D.; Treskov, K.; Tsang, K. V.; Tull, C. E.; Viaux, N.; Viren, B.; Vorobel, V.; Wang, C. H.; Wang, M.; Wang, N. Y.; Wang, R. G.; Wang, W.; Wang, X.; Wang, Y. F.; Wang, Z.; Wang, Z.; Wang, Z. M.; Wei, H. Y.; Wen, L. J.; Whisnant, K.; White, C. G.; Whitehead, L.; Wise, T.; Wong, H. L. H.; Wong, S. C. F.; Worcester, E.; Wu, C.-H.; Wu, Q.; Wu, W. J.; Xia, D. M.; Xia, J. K.; Xing, Z. Z.; Xu, J. Y.; Xu, J. L.; Xu, Y.; Xue, T.; Yang, C. G.; Yang, H.; Yang, L.; Yang, M. S.; Yang, M. T.; Ye, M.; Ye, Z.; Yeh, M.; Young, B. L.; Yu, Z. Y.; Zeng, S.; Zhan, L.; Zhang, C.; Zhang, H. H.; Zhang, J. W.; Zhang, Q. M.; Zhang, X. T.; Zhang, Y. M.; Zhang, Y. X.; Zhang, Y. M.; Zhang, Z. J.; Zhang, Z. Y.; Zhang, Z. P.; Zhao, J.; Zhao, Q. W.; Zhao, Y. B.; Zhong, W. L.; Zhou, L.; Zhou, N.; Zhuang, H. L.; Zou, J. H.; Daya Bay Collaboration

    2017-01-01

    A new measurement of the reactor antineutrino flux and energy spectrum by the Daya Bay reactor neutrino experiment is reported. The antineutrinos were generated by six 2.9 GWth nuclear reactors and detected by eight antineutrino detectors deployed in two near (560 m and 600 m flux-weighted baselines) and one far (1640 m flux-weighted baseline) underground experimental halls. With 621 days of data, more than 1.2 million inverse beta decay (IBD) candidates were detected. The IBD yield in the eight detectors was measured, and the ratio of measured to predicted flux was found to be 0.946±0.020 (0.992±0.021) for the Huber+Mueller (ILL+Vogel) model. A 2.9σ deviation was found in the measured IBD positron energy spectrum compared to the predictions. In particular, an excess of events in the region of 4-6 MeV was found in the measured spectrum, with a local significance of 4.4σ. A reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions. Supported in part by the Ministry of Science and Technology of China, the United States Department of Energy, the Chinese Academy of Sciences, the CAS Center for Excellence in Particle Physics, the National Natural Science Foundation of China, the Guangdong provincial government, the Shenzhen municipal government, the China General Nuclear Power Group, the Research Grants Council of the Hong Kong Special Administrative Region of China, the MOST and MOE in Taiwan, the U.S. National Science Foundation, the Ministry of Education, Youth and Sports of the Czech Republic, the Joint Institute of Nuclear Research in Dubna, Russia, the NSFC-RFBR joint research program, the National Commission for Scientific and Technological Research of Chile

  16. Absolute and relative educational inequalities in depression in Europe.

    PubMed

    Dudal, Pieter; Bracke, Piet

    2016-09-01

    To investigate (1) the size of absolute and relative educational inequalities in depression, (2) their variation between European countries, and (3) their relationship with underlying prevalence rates. Analyses are based on the European Social Survey, rounds three and six (N = 57,419). Depression is measured using the shortened Centre of Epidemiologic Studies Depression Scale. Education is coded by use of the International Standard Classification of Education. Country-specific logistic regressions are applied. Results point to an elevated risk of depressive symptoms among the lower educated. The cross-national patterns differ between absolute and relative measurements. For men, large relative inequalities are found for countries including Denmark and Sweden, but are accompanied by small absolute inequalities. For women, large relative and absolute inequalities are found in Belgium, Bulgaria, and Hungary. Results point to an empirical association between inequalities and the underlying prevalence rates. However, the strength of the association is only moderate. This research stresses the importance of including both measurements for comparative research and suggests the inclusion of the level of population health in research into inequalities in health.

  17. Characterization of extreme air-sea turbulent fluxes

    NASA Astrophysics Data System (ADS)

    Gulev, Sergey; Belyaev, Konstantin

    2017-04-01

    Extreme ocean-atmosphere turbulent fluxes play a critical role in the convective processes in the mid and subpolar latitudes and may also affect a variety of atmospheric processes, such as generation and re-intensification of extreme cyclones in the areas of the mid latitude storm tracks. From the ocean dynamics perspective, specifically for quantifying extreme vertical mixing, characterization of the extreme fluxes requires, besides estimation of the extreme events, also consideration of the relative extremeness of surface fluxes and their timing, e.g. the duration of periods of high surface fluxes. In order to comprehensively characterize extreme turbulent fluxes at sea surface we propose a formalism based upon probability density distributions of surface turbulent fluxes and flux-related variables. Individual absolute flux extremes were derived using Modified Fisher-Tippett (MFT) distribution of turbulent fluxes. Then, we extend this distribution to the fractional distribution, characterizing the fraction of time-integrated turbulent heat flux provided by the fluxes exceeding a given percentile. Finally, we consider the time durations during which fluxes of a given intensity provide extreme accumulations of heat loss from the surface. For estimation of these characteristics of surface fluxes we use fluxes recomputed from the state variables available from modern era reanalyses (ERA-Interim, MERRA and CFSR) for the period from 1979 onwards. Applications of the formalism to the VOS (Voluntary Observing Ship) - based surface fluxes are also considered. We discuss application of the new metrics of mesoscale and synoptic variability of surface fluxes to the dynamics of mixed layer depth in the North Atlantic.

  18. ArtDeco: a beam-deconvolution code for absolute cosmic microwave background measurements

    NASA Astrophysics Data System (ADS)

    Keihänen, E.; Reinecke, M.

    2012-12-01

    We present a method for beam-deconvolving cosmic microwave background (CMB) anisotropy measurements. The code takes as input the time-ordered data along with the corresponding detector pointings and known beam shapes, and produces as output the harmonic aTlm, aElm, and aBlm coefficients of the observed sky. From these one can derive temperature and Q and U polarisation maps. The method is applicable to absolute CMB measurements with wide sky coverage, and is independent of the scanning strategy. We tested the code with extensive simulations, mimicking the resolution and data volume of Planck 30 GHz and 70 GHz channels, but with exaggerated beam asymmetry. We applied it to multipoles up to l = 1700 and examined the results in both pixel space and harmonic space. We also tested the method in presence of white noise. The code is released under the terms of the GNU General Public License and can be obtained from http://sourceforge.net/projects/art-deco/

  19. Aerosol and trace gas flux measurements from a mobile car platform on the highway

    NASA Astrophysics Data System (ADS)

    Gordon, M.; Miller, S. J.; Staebler, R. M.; Taylor, P.

    2016-12-01

    Mobile flux measurements of aerosols and trace gases at the surface can provide valuable information about the vertical transport of these compounds from near-surface sources. These measurements can be complimentary to stationary tower measurements or elevated mobile measurements from aircraft and unmanned aerial systems (UAS). In July, 2016 a mobile platform (Toyota Highlander), outfitted with a sonic anemometer (ATI), an open path CO2/H2O analyzer (Licor), and an ultrafine particle sizer (DMT), was driven on highways as part of a chasing study to investigate vehicle-induced turbulence and mixing. The open path analyzer and particle sizer inlet were co-located with the anemometer in order to investigate the feasibility of making flux measurements of heat, momentum, water vapour, CO2, and sub-micron aerosols on the highway. These highway flux measurements are compared to stationary platform measurements made upwind and downwind of the highway. Statistical and spectral analyses are used to demonstrate the validity of the mobile measurements. Uncertainties due to flow distortion around the vehicle, under-sampling, and heterogeneity of the vertical temperature and concentrations are investigated and discussed.

  20. Repeat Absolute and Relative Gravity Measurements for Geothermal Reservoir Monitoring in the Ogiri Geothermal Field, Southern Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Nishijima, J.; Umeda, C.; Fujimitsu, Y.; Takayama, J.; Hiraga, N.; Higuchi, S.

    2016-09-01

    Repeat hybrid microgravity measurements were conducted around the Ogiri Geothermal Field on the western slope of Kirishima volcano, southern Kyushu, Japan. This study was undertaken to detect the short-term gravity change caused by the temporary shutdown of production and reinjection wells for regular maintenance in 2011 and 2013. Repeat microgravity measurements were taken using an A-10 absolute gravimeter (Micro-g LaCoste) and CG-5 gravimeter (Scintrex) before and after regular maintenance. Both instruments had an accuracy of 10 μgal. The gravity stations were established at 27 stations (two stations for absolute measurements and 25 stations for relative measurements). After removal of noise effects (e.g., tidal movement, precipitation, shallow groundwater level changes), the residual gravity changes were subdivided into five types of response. We detected a gravity decrease (up to 20 μgal) in the reinjection area and a gravity increase (up to 30 μgal) in the production area 1 month after the temporary shutdown. Most of the gravity stations recovered after the maintenance. The temporal density changes in the geothermal reservoir were estimated based on these gravity changes.

  1. Surface Flux Measurements at King Sejong Station in West Antarctica

    NASA Astrophysics Data System (ADS)

    Choi, T.; Lee, B.; Lee, H.; Shim, J.

    2004-12-01

    The Antarctic Peninsula is important in terms of global warming research due to pronounced increase of air temperature over the last century. The first eddy covariance system was established and turbulent fluxes of heat, water vapor, CO2 and momentum have been measured at King Sejong Station (62 \\deg 13øØS, 58 \\deg 47øØW) located in the northern edge of the Antarctic Peninsula since December in 2002. Our objectives are to better understand the interactions between the Antarctic land surface and the atmosphere and to test the feasibility of the long-term operation of eddy covariance system under extreme weather conditions. Various lichens cover the study area and the dominant species is Usnea fasciata-Himantormia. Based on the analyses on turbulent statistics such as integral turbulence characteristics of vertical velocity (w) and heat (T), stationarity test and investigation of correlation coefficient, they follow the Monin-Obukhov similarity and eddy covariance flux data were reliable. About 50 % of total retrieved sensible heat flux data could be used for further analysis. We will report on seasonal variations of energy and mass fluxes and environmental variables. In addition, factors controlling these fluxes will be presented. Acknowledgement: This study was supported by ¡rEnvironmental Monitoring on Human Impacts at the King Sejong Station, Antarctica¡_ (Project PP04102 of Korea Polar Research Institute) and ¡rEco-technopia 21 project¡_ (Ministry of Environment of Korea).

  2. Absolute orbit determination using line-of-sight vector measurements between formation flying spacecraft

    NASA Astrophysics Data System (ADS)

    Ou, Yangwei; Zhang, Hongbo; Li, Bin

    2018-04-01

    The purpose of this paper is to show that absolute orbit determination can be achieved based on spacecraft formation. The relative position vectors expressed in the inertial frame are used as measurements. In this scheme, the optical camera is applied to measure the relative line-of-sight (LOS) angles, i.e., the azimuth and elevation. The LIDAR (Light radio Detecting And Ranging) or radar is used to measure the range and we assume that high-accuracy inertial attitude is available. When more deputies are included in the formation, the formation configuration is optimized from the perspective of the Fisher information theory. Considering the limitation on the field of view (FOV) of cameras, the visibility of spacecraft and the installation of cameras are investigated. In simulations, an extended Kalman filter (EKF) is used to estimate the position and velocity. The results show that the navigation accuracy can be enhanced by using more deputies and the installation of cameras significantly affects the navigation performance.

  3. Continuous measurements of methane flux in two Japanese temperate forests based on the micrometeorological and chamber methods

    NASA Astrophysics Data System (ADS)

    Yoshikawa, K.; Ueyama, M.; Takagi, K.; Kominami, Y.

    2015-12-01

    Methane (CH4) budget in forest ecosystems have not been accurately quantified due to limited measurements and considerable spatiotemporal heterogeneity. In order to quantify CH4 fluxes at temperate forest at various spatiotemporal scales, we have continuously measured CH4 fluxes at two upland forests based on the micrometeorological hyperbolic relaxed eddy accumulation (HREA) and automated dynamic closed chamber methods.The measurements have been conducted at Teshio experimental forest (TSE) since September 2013 and Yamashiro forest meteorology research site (YMS) since November 2014. Three automated chambers were installed on each site. Our system can measure CH4 flux by the micrometeorological HREA, vertical concentration profile at four heights, and chamber measurements by a laser-based gas analyzer (FGGA-24r-EP, Los Gatos Research Inc., USA).Seasonal variations of canopy-scale CH4 fluxes were different in each site. CH4 was consumed during the summer, but was emitted during the fall and winter in TSE; consequently, the site acted as a net annual CH4 source. CH4 was steadily consumed during the winter, but CH4 fluxes fluctuated between absorption and emission during the spring and summer in YMS. YMS acted as a net annual CH4 sink. CH4 uptake at the canopy scale generally decreased with rising soil temperature and increased with drying condition for both sites. CH4 flux measured by most of chambers showed the consistent sensitivity examined for the canopy scale to the environmental variables. CH4 fluxes from a few chambers located at a wet condition were independent of variations in soil temperature and moisture at both sites. Magnitude of soil CH4 uptake was higher than the canopy-scale CH4 uptake. Our results showed that the canopy-scale CH4 fluxes were totally different with the plot-scale CH4 fluxes by chambers, suggesting the considerable spatial heterogeneity in CH4 flux at the temperate forests.

  4. Absolute calibration of neutron detectors on the C-2U advanced beam-driven FRC.

    PubMed

    Magee, R M; Clary, R; Korepanov, S; Jauregui, F; Allfrey, I; Garate, E; Valentine, T; Smirnov, A

    2016-11-01

    In the C-2U fusion energy experiment, high power neutral beam injection creates a large fast ion population that sustains a field-reversed configuration (FRC) plasma. The diagnosis of the fast ion pressure in these high-performance plasmas is therefore critical, and the measurement of the flux of neutrons from the deuterium-deuterium (D-D) fusion reaction is well suited to the task. Here we describe the absolute, in situ calibration of scintillation neutron detectors via two independent methods: firing deuterium beams into a high density gas target and calibration with a 2 × 10 7 n/s AmBe source. The practical issues of each method are discussed and the resulting calibration factors are shown to be in good agreement. Finally, the calibration factor is applied to C-2U experimental data where the measured neutron rate is found to exceed the classical expectation.

  5. Absolute laser-intensity measurement and online monitor calibration using a calorimeter at a soft X-ray free-electron laser beamline in SACLA

    NASA Astrophysics Data System (ADS)

    Tanaka, Takahiro; Kato, Masahiro; Saito, Norio; Owada, Shigeki; Tono, Kensuke; Yabashi, Makina; Ishikawa, Tetsuya

    2018-06-01

    This paper reports measurement of the absolute intensity of free-electron laser (FEL) and calibration of online intensity monitors for a brand-new FEL beamline BL1 at SPring-8 Angstrom Compact free-electron LAser (SACLA) in Japan. To measure the absolute intensity of FEL, we used a room-temperature calorimeter originally developed for FELs in the hard X-ray range. By using the calorimeter, we calibrated online intensity monitors of BL1, gas monitors (GMs), based on the photoionization of argon gas, in the photon energy range from 25 eV to 150 eV. A good correlation between signals obtained from the calorimeter and GMs was observed in the pulse energy range from 1 μJ to 100 μJ, where the upper limit is nearly equal to the maximum pulse energy at BL1. Moreover, the calibration result of the GMs, measured in terms of the spectral responsivity, demonstrates a characteristic photon-energy dependence owing to the occurrence of the Cooper minimum in the total ionization cross-section of argon gas. These results validate the feasibility of employing the room-temperature calorimeter in the measurement of absolute intensity of FELs over the specified photon energy range.

  6. A new frontier in CO2 flux measurements using a highly portable DIAL laser system

    PubMed Central

    Queiβer, Manuel; Granieri, Domenico; Burton, Mike

    2016-01-01

    Volcanic CO2 emissions play a key role in the geological carbon cycle, and monitoring of volcanic CO2 fluxes helps to forecast eruptions. The quantification of CO2 fluxes is challenging due to rapid dilution of magmatic CO2 in CO2-rich ambient air and the diffuse nature of many emissions, leading to large uncertainties in the global magmatic CO2 flux inventory. Here, we report measurements using a new DIAL laser remote sensing system for volcanic CO2 (CO2DIAL). Two sites in the volcanic zone of Campi Flegrei (Italy) were scanned, yielding CO2 path-amount profiles used to compute fluxes. Our results reveal a relatively high CO2 flux from Campi Flegrei, consistent with an increasing trend. Unlike previous methods, the CO2DIAL is able to measure integrated CO2 path-amounts at distances up to 2000 m using virtually any solid surface as a reflector, whilst also being highly portable. This opens a new frontier in quantification of geological and anthropogenic CO2 fluxes. PMID:27652775

  7. What do magnetic resonance-based measurements of Pi→ATP flux tell us about skeletal muscle metabolism?

    PubMed

    Kemp, Graham J; Brindle, Kevin M

    2012-08-01

    Magnetic resonance spectroscopy (MRS) methods offer a potentially valuable window into cellular metabolism. Measurement of flux between inorganic phosphate (Pi) and ATP using (31)P MRS magnetization transfer has been used in resting muscle to assess what is claimed to be mitochondrial ATP synthesis and has been particularly popular in the study of insulin effects and insulin resistance. However, the measured Pi→ATP flux in resting skeletal muscle is far higher than the true rate of oxidative ATP synthesis, being dominated by a glycolytically mediated Pi↔ATP exchange reaction that is unrelated to mitochondrial function. Furthermore, even if measured accurately, the ATP production rate in resting muscle has no simple relationship to mitochondrial capacity as measured either ex vivo or in vivo. We summarize the published measurements of Pi→ATP flux, concentrating on work relevant to diabetes and insulin, relate it to current understanding of the physiology of mitochondrial ATP synthesis and glycolytic Pi↔ATP exchange, and discuss some possible implications of recently reported correlations between Pi→ATP flux and other physiological measures.

  8. Third law of thermodynamics in the presence of a heat flux

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Camacho, J.

    1995-01-01

    Following a maximum entropy formalism, we study a one-dimensional crystal under a heat flux. We obtain the phonon distribution function and evaluate the nonequilibrium temperature, the specific heat, and the entropy as functions of the internal energy and the heat flux, in both the quantum and the classical limits. Some analogies between the behavior of equilibrium systems at low absolute temperature and nonequilibrium steady states under high values of the heat flux are shown, which point to a possible generalization of the third law in nonequilibrium situations.

  9. Relative and absolute reliability of measures of linoleic acid-derived oxylipins in human plasma.

    PubMed

    Gouveia-Figueira, Sandra; Bosson, Jenny A; Unosson, Jon; Behndig, Annelie F; Nording, Malin L; Fowler, Christopher J

    2015-09-01

    Modern analytical techniques allow for the measurement of oxylipins derived from linoleic acid in biological samples. Most validatory work has concerned extraction techniques, repeated analysis of aliquots from the same biological sample, and the influence of external factors such as diet and heparin treatment upon their levels, whereas less is known about the relative and absolute reliability of measurements undertaken on different days. A cohort of nineteen healthy males were used, where samples were taken at the same time of day on two occasions, at least 7 days apart. Relative reliability was assessed using Lin's concordance correlation coefficients (CCC) and intraclass correlation coefficients (ICC). Absolute reliability was assessed by Bland-Altman analyses. Nine linoleic acid oxylipins were investigated. ICC and CCC values ranged from acceptable (0.56 [13-HODE]) to poor (near zero [9(10)- and 12(13)-EpOME]). Bland-Altman limits of agreement were in general quite wide, ranging from ±0.5 (12,13-DiHOME) to ±2 (9(10)-EpOME; log10 scale). It is concluded that relative reliability of linoleic acid-derived oxylipins varies between lipids with compounds such as the HODEs showing better relative reliability than compounds such as the EpOMEs. These differences should be kept in mind when designing and interpreting experiments correlating plasma levels of these lipids with factors such as age, body mass index, rating scales etc. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. A novel capacitive absolute positioning sensor based on time grating with nanometer resolution

    NASA Astrophysics Data System (ADS)

    Pu, Hongji; Liu, Hongzhong; Liu, Xiaokang; Peng, Kai; Yu, Zhicheng

    2018-05-01

    The present work proposes a novel capacitive absolute positioning sensor based on time grating. The sensor includes a fine incremental-displacement measurement component combined with a coarse absolute-position measurement component to obtain high-resolution absolute positioning measurements. A single row type sensor was proposed to achieve fine displacement measurement, which combines the two electrode rows of a previously proposed double-row type capacitive displacement sensor based on time grating into a single row. To achieve absolute positioning measurement, the coarse measurement component is designed as a single-row type displacement sensor employing a single spatial period over the entire measurement range. In addition, this component employs a rectangular induction electrode and four groups of orthogonal discrete excitation electrodes with half-sinusoidal envelope shapes, which were formed by alternately extending the rectangular electrodes of the fine measurement component. The fine and coarse measurement components are tightly integrated to form a compact absolute positioning sensor. A prototype sensor was manufactured using printed circuit board technology for testing and optimization of the design in conjunction with simulations. Experimental results show that the prototype sensor achieves a ±300 nm measurement accuracy with a 1 nm resolution over a displacement range of 200 mm when employing error compensation. The proposed sensor is an excellent alternative to presently available long-range absolute nanometrology sensors owing to its low cost, simple structure, and ease of manufacturing.

  11. Large Area Lunar Dust Flux Measurement Instrument

    NASA Technical Reports Server (NTRS)

    Corsaro, R.; Giovane, F.; Liou, Jer-Chyi; Burchell, M.; Stansbery, Eugene; Lagakos, N.

    2009-01-01

    The instrument under development is designed to characterize the flux and size distribution of the lunar micrometeoroid and secondary ejecta environment. When deployed on the lunar surface, the data collected will benefit fundamental lunar science as well as enabling more reliable impact risk assessments for human lunar exploration activities. To perform this task, the instrument requirements are demanding. It must have as large a surface area as possible to sample the very sparse population of the larger potentially damage-inducing micrometeorites. It must also have very high sensitivity to enable it to measure the flux of small (<10 micron) micrometeorite and secondary ejecta dust particles. To be delivered to the lunar surface, it must also be very low mass, rugged and stow compactly. The instrument designed to meet these requirements is called FOMIS. It is a large-area thin film under tension (i.e. a drum) with multiple fiber optic displacement (FOD) sensors to monitor displacements of the film. This sensor was chosen since it can measure displacements over a wide dynamic range: 1 cm to sub-Angstrom. A prototype system was successfully demonstrated using the hypervelocity impact test facility at the University of Kent (Canterbury, UK). Based on these results, the prototype system can detect hypervelocity (approx.5 km/s) impacts by particles as small as 2 microns diameter. Additional tests using slow speeds find that it can detect secondary ejecta particles (which do not penetrate the film) with momentums as small as 15 pico-gram 100m/s, or nominally 5 microns diameter at 100 m/s.

  12. Direct measurements of vertical heat flux and Na flux in the mesosphere and lower thermosphere by lidar at Boulder (40°N, 105°W), Colorado

    NASA Astrophysics Data System (ADS)

    Huang, W.; Chu, X.; Gardner, C. S.; Barry, I. F.; Smith, J. A.; Fong, W.; Yu, Z.; Chen, C.

    2014-12-01

    The vertical transport of heat and constituent by gravity waves and tides plays a fundamental role in establishing the thermal and constituent structures of the mesosphere and lower thermosphere (MLT), but has not been thoroughly investigated by observations. In particular, direct measurements of vertical heat flux and metal constituent flux caused by dissipating waves are extremely rare, which demand precise measurements with high spatial and temporal resolutions over a long period. Such requirements are necessary to overcome various uncertainties to reveal the small quantities of the heat and constituent fluxes induced by dissipating waves. So far such direct observations have only been reported for vertical heat and Na fluxes using a Na Doppler lidar at Starfire Optical Range (SOR) in Albuquerque, New Mexico. Furthermore, estimate of eddy heat and constituent fluxes from the turbulent mixing generated by breaking waves is even more challenging due to the even smaller temporal and spatial scales of the eddy. Consequently, the associated coefficients of thermal (kH) and constituent (kzz) diffusion have not been well characterized and remain as large uncertainties in models. We attempt to address these issues with direct measurements by a Na Doppler lidar with exceptional high-resolution measurement capabilities. Since summer 2010, we have been operating a Na Doppler lidar at Boulder, Colorado. The efficiency of the lidar has been greatly improved in summer of 2011 and achieved generally over 1000 counts of Na signal per lidar pulse in winter. In 2013, we made extensive Na lidar observations in 98 nights. These data covering each month of a full year will be used to characterize the seasonal variations of heat and Na fluxes and to be compared with the pioneering observations at SOR. In November 2013, we further upgraded the lidar with two new frequency shifters and a new data acquisition scheme, which are optimized for estimating eddy fluxes and reducing the

  13. Precision flux density measurements of the giant planets at 8420 MHz

    NASA Technical Reports Server (NTRS)

    Turegano, J. A.; Klein, M. J.

    1981-01-01

    Precision measurements of the 3.56 cm flux densities of Jupiter, Saturn, Uranus, and Neptune are reported. The results are compared with previously published measurements as a means of: (1) remotely sensing long-term changes in the microwave emission from the atmospheres of these planets; (2) measuring the effects of Saturn's rings on the disk temperature as observed from earth at different ring inclination angles.

  14. Precision flux density measurements of the giant planets at 8420 MHz

    NASA Technical Reports Server (NTRS)

    Turegano, J. A.; Klein, M. J.

    1981-01-01

    Precision measurements of the 3.56 cm flux densities of Jupiter, Saturn, Uranus, and Neptune are reported. The results are compared with previously published measurements as a means of: remotely sensing long-term changes in the microwave emission from the atmospheres of these planets and measuring the effects of Saturn's rings on the disk temperature as observed from earth at different ring inclination angles.

  15. Absolute and Relative Socioeconomic Health Inequalities across Age Groups

    PubMed Central

    van Zon, Sander K. R.; Bültmann, Ute; Mendes de Leon, Carlos F.; Reijneveld, Sijmen A.

    2015-01-01

    Background The magnitude of socioeconomic health inequalities differs across age groups. It is less clear whether socioeconomic health inequalities differ across age groups by other factors that are known to affect the relation between socioeconomic position and health, like the indicator of socioeconomic position, the health outcome, gender, and as to whether socioeconomic health inequalities are measured in absolute or in relative terms. The aim is to investigate whether absolute and relative socioeconomic health inequalities differ across age groups by indicator of socioeconomic position, health outcome and gender. Methods The study sample was derived from the baseline measurement of the LifeLines Cohort Study and consisted of 95,432 participants. Socioeconomic position was measured as educational level and household income. Physical and mental health were measured with the RAND-36. Age concerned eleven 5-years age groups. Absolute inequalities were examined by comparing means. Relative inequalities were examined by comparing Gini-coefficients. Analyses were performed for both health outcomes by both educational level and household income. Analyses were performed for all age groups, and stratified by gender. Results Absolute and relative socioeconomic health inequalities differed across age groups by indicator of socioeconomic position, health outcome, and gender. Absolute inequalities were most pronounced for mental health by household income. They were larger in younger than older age groups. Relative inequalities were most pronounced for physical health by educational level. Gini-coefficients were largest in young age groups and smallest in older age groups. Conclusions Absolute and relative socioeconomic health inequalities differed cross-sectionally across age groups by indicator of socioeconomic position, health outcome and gender. Researchers should critically consider the implications of choosing a specific age group, in addition to the indicator of

  16. Surface Catalysis and Oxidation on Stagnation Point Heat Flux Measurements in High Enthalpy Arc Jets

    NASA Technical Reports Server (NTRS)

    Nawaz, Anuscheh; Driver, David M.; Terrazas-Salinas

    2013-01-01

    Heat flux sensors are routinely used in arc jet facilities to determine heat transfer rates from plasma plume. The goal of this study is to assess the impact of surface composition changes on these heat flux sensors. Surface compositions can change due to oxidation and material deposition from the arc jet. Systematic surface analyses of the sensors were conducted before and after exposure to plasma. Currently copper is commonly used as surface material. Other surface materials were studied including nickel, constantan gold, platinum and silicon dioxide. The surfaces were exposed to plasma between 0.3 seconds and 3 seconds. Surface changes due to oxidation as well as copper deposition from the arc jets were observed. Results from changes in measured heat flux as a function of surface catalycity is given, along with a first assessment of enthalpy for these measurements. The use of cupric oxide is recommended for future heat flux measurements, due to its consistent surface composition arc jets.

  17. Carbon fluxes in a heterogeneous estuarine wetland in Northern Ohio. Comparing eddy covariance and chamber measurements

    NASA Astrophysics Data System (ADS)

    Rey Sanchez, C.; Morin, T. H.; Stefanik, K. C.; Wrighton, K. C.; Bohrer, G.

    2016-12-01

    Wetlands are important carbon dioxide (CO2) sinks but also the largest source of methane (CH4), a powerful greenhouse gas. Wetlands are often heterogeneous landscapes with highly diverse land covers and different paths of CH4 release and CO2 uptake. Understanding the ecosystem level greenhouse gas budget of a wetland involves understanding several carbon fluxes associated with each of the different land cover patches. We studied CO2 and CH4 fluxes from different land cover types at the Old Woman Creek (OWC) National Estuarine Research Reserve, at the Lake Erie shore in Northern Ohio. OWC is composed of four main types of land cover: open water, emergent cattail vegetation (Typha spp), floating vegetation (Nelimbo spp), and mud flats. CH4 and CO2 gas exchange was measured in each patch type using enclosed chambers monthly during the growing seasons of 2015 and 2016. During the same period of time, an eddy covariance tower was deployed in a representative section of the wetland to measure continuous site-level CO2 and CH4 fluxes. A footprint model was used to account for the relative contributions of each patch type to the flux measured by the tower. The chamber measurements were used to constrain the contributions of each patch within the flux tower footprint, and to correct the flux measurements to the whole-wetland total flux. We analyzed the spatial and temporal variability of methane and carbon dioxide and related this variation to some of the most important environmental drivers at the site. We used these data to analyze the implications of different arrangements of land cover types on the carbon balance and greenhouse-gas budget in wetlands.

  18. Thermophysical Property Measurements of Molten Slag and Welding Flux by Aerodynamic Levitator

    NASA Astrophysics Data System (ADS)

    Onodera, Kenta; Nakamura, Airi; Hakamada, Shinya; Watanabe, Masahito; Kargl, Florian

    Molten slag and welding flux are important materials for steel processing. Due to lack of durable refractory materials, there is limited publication data on the thermophysical properties of these slags. Therefore, in this study, we measured density and viscosity of CaO-Al2O3-SiO2 slag and welding flux using Aerodynamic Levitation (ADL) with CO2-laser heating in which can be achieve containerless and non-contacting conditions for measurements. For density measurements, in order to obtain correct shape of the droplet we used high-speed camera with the extended He-Ne laser to project the shadow image without the influence of the selfluminescence at the high temperature. For viscosity measurement, we also have a unique vibration method; it caused oscillation in a sample by letting gas for levitation vibrate by an acoustic speaker. Using these techniques, we succeeded to measure systematically density and viscosity of molten oxides system.

  19. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  20. High-resolution absolute position detection using a multiple grating

    NASA Astrophysics Data System (ADS)

    Schilling, Ulrich; Drabarek, Pawel; Kuehnle, Goetz; Tiziani, Hans J.

    1996-08-01

    To control electro-mechanical engines, high-resolution linear and rotary encoders are needed. Interferometric methods (grating interferometers) promise a resolution of a few nanometers, but have an ambiguity range of some microns. Incremental encoders increase the absolute measurement range by counting the signal periods starting from a defined initial point. In many applications, however, it is not possible to move to this initial point, so that absolute encoders have to be used. Absolute encoders generally have a scale with two or more tracks placed next to each other. Therefore, they use a two-dimensional grating structure to measure a one-dimensional position. We present a new method, which uses a one-dimensional structure to determine the position in one dimension. It is based on a grating with a large grating period up to some millimeters, having the same diffraction efficiency in several predefined diffraction orders (multiple grating). By combining the phase signals of the different diffraction orders, it is possible to establish the position in an absolute range of the grating period with a resolution like incremental grating interferometers. The principal functionality was demonstrated by applying the multiple grating in a heterodyne grating interferometer. The heterodyne frequency was generated by a frequency modulated laser in an unbalanced interferometer. In experimental measurements an absolute range of 8 mm was obtained while achieving a resolution of 10 nm.

  1. Characterization And Partitioning Of CH4 And CO2 Eddy Flux Data Measured at NGEE-Arctic Sites

    NASA Astrophysics Data System (ADS)

    Dengel, S.; Chafe, O.; Curtis, J. B.; Biraud, S.; Torn, M. S.; Wullschleger, S. D.

    2017-12-01

    The high latitudes are experiencing rapid warming with permafrost ecosystems being highly vulnerable to this change. Since the advancement in Eddy Covariance (EC) measurements, the number of high latitude sites measuring greenhouse gases and energy (CO2, CH4 and H2O) fluxes is steadily increasing, with new sites being established each year. Data from these sites are not only valuable for annual carbon budget calculations, but also vital to the modeling community for improving their predictions of emission rates and trends. CH4 flux measurements are not as straightforward as CO2 fluxes. They tend to be less predictable or as easily interpretable as CO2 fluxes. Understanding CH4 emission patterns are often challenging. Moreover, gas flux fluctuations are spatially and temporally diverse, and in many cases event-based. An improvement in understanding would also contribute to improvements in the fidelity of model predictions. These rely on having high quality data, and thus will entail developing new QA/QC and gap-filling methods for Arctic systems, in particularly for CH4. Contributing to these challenges is the limited number of ancillary measurements carried out at many sites and the lack of standardized data processing, QA/QC, and gap-filling procedures, in particular for CH4. CO2, CH4, and energy flux measurements are ongoing at, both NGEE-Arctic/AmeriFlux, US-NGB (Arctic coastal plain), and US-NGC (subarctic tussock tundra) sites. The sites, with underlying continuous permafrost, show a high degree of inter-annual and seasonal variability in CH4 fluxes. In order to interpret this variability, we apply a variety of models, such as footprint characterization, generalized additive models, as well as artificial neural networks, in an attempt to decipher these diverse fluxes, patterns and events.

  2. A Carbon Flux Super Site. New Insights and Innovative Atmosphere-Terrestrial Carbon Exchange Measurements and Modeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Leclerc, Monique Y.

    2014-11-17

    This final report presents the main activities and results of the project “A Carbon Flux Super Site: New Insights and Innovative Atmosphere-Terrestrial Carbon Exchange Measurements and Modeling” from 10/1/2006 to 9/30/2014. It describes the new AmeriFlux tower site (Aiken) at Savanna River Site (SC) and instrumentation, long term eddy-covariance, sodar, microbarograph, soil and other measurements at the site, and intensive field campaigns of tracer experiment at the Carbon Flux Super Site, SC, in 2009 and at ARM-CF site, Lamont, OK, and experiments in Plains, GA. The main results on tracer experiment and modeling, on low-level jet characteristics and their impactmore » on fluxes, on gravity waves and their influence on eddy fluxes, and other results are briefly described in the report.« less

  3. Absolute measurement of cerebral optical coefficients, hemoglobin concentration and oxygen saturation in old and young adults with near-infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    We present near-infrared spectroscopy measurement of absolute cerebral hemoglobin concentration and saturation in a large sample of 36 healthy elderly (mean age, 85 ± 6 years) and 19 young adults (mean age, 28 ± 4 years). Non-invasive measurements were obtained on the forehead using a commercially a...

  4. The development and validation of an unmanned aerial system (UAS) for the measurement of methane flux

    NASA Astrophysics Data System (ADS)

    Allen, G.; Shah, A.; Williams, P. I.; Ricketts, H.; Hollingsworth, P.; Kabbabe, K.; Bourn, M.; Pitt, J. R.; Helmore, J.; Lowry, D.; Robinson, R. A.; Finlayson, A.

    2017-12-01

    Emission controls for CH4are a part of the Paris Agreement and other national emissions strategies. This work represents a new method for precise quantification of point-source and facility-level methane emissions flux rates to inform both the climate science community and policymakers. In this paper, we describe the development of an integrated Unmanned Aerial System (UAS) for the measurement of high-precision in-situ CH4 concentrations. We also describe the development of a mass balance flux calculation model tailored to UAS plume sampling downwind; and the validation of this method using a known emission flux from a controlled release facility. A validation field trial was conducted at the UK Met Office site in Cardington, UK, between 31 Oct and 4 Nov 2016 using the UK National Physical Laboratory's Controlled Release Facility (CRF). A modified DJI-S900 hexrotor UAS was tethered via an inlet to a ground-based Los Gatos Ultraportable Greenhouse Gas Analyser to record geospatially-referenced methane (and carbon dioxide) concentrations. Methane fluxes from the CRF were emitted at 5 kg/hr and 10 kg/hr in a series of blind trials (fluxes were not reported to the team prior to the calculation of UAS-derived flux) for a total of 7 UAS flights, which sampled 200 m downwind of source(s), each lasting around 20 minutes. The flux calculation method was adapted for sampling considerations downwind of an emission source that has not had sufficient time to develop a Gaussian morphology. The UAS-measured methane fluxes, and representative flux uncertainty (derived from an error propagation model), were found to compare well with the controlled CH4 emission rate. For the 7 experiments, the standard error between the measured and emitted CH4 flux was found to be +/-6% with a mean bias of +0.4 kg/hr. Limits of flux sensitivity (to within 25% uncertainty) were found to extend to as little as 0.12 kg/h. Further improvements to the accuracy of flux calculation could be made by

  5. Local Magnetic Measurements of Trapped Flux Through a Permanent Current Path in Graphite

    NASA Astrophysics Data System (ADS)

    Stiller, Markus; Esquinazi, Pablo D.; Quiquia, José Barzola; Precker, Christian E.

    2018-04-01

    Temperature- and field-dependent measurements of the electrical resistance of different natural graphite samples suggest the existence of superconductivity at room temperature in some regions of the samples. To verify whether dissipationless electrical currents are responsible for the trapped magnetic flux inferred from electrical resistance measurements, we localized them using magnetic force microscopy on a natural graphite sample in remanent state after applying a magnetic field. The obtained evidence indicates that at room temperature a permanent current flows at the border of the trapped flux region. The current path vanishes at the same transition temperature T_c≈ 370 K as the one obtained from electrical resistance measurements on the same sample. This sudden decrease in the phase is different from what is expected for a ferromagnetic material. Time-dependent measurements of the signal show the typical behavior of flux creep of a permanent current flowing in a superconductor. The overall results support the existence of room-temperature superconductivity at certain regions in the graphite structure and indicate that magnetic force microscopy is suitable to localize them. Magnetic coupling is excluded as origin of the observed phase signal.

  6. Absolute nuclear material assay using count distribution (LAMBDA) space

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Prasad, Mano K.; Snyderman, Neal J.; Rowland, Mark S.

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  7. Absolute nuclear material assay using count distribution (LAMBDA) space

    DOEpatents

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2012-06-05

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  8. A new time of flight mass spectrometer for absolute dissociative electron attachment cross-section measurements in gas phase

    NASA Astrophysics Data System (ADS)

    Chakraborty, Dipayan; Nag, Pamir; Nandi, Dhananjay

    2018-02-01

    A new time of flight mass spectrometer (TOFMS) has been developed to study the absolute dissociative electron attachment (DEA) cross section using a relative flow technique of a wide variety of molecules in gas phase, ranging from simple diatomic to complex biomolecules. Unlike the Wiley-McLaren type TOFMS, here the total ion collection condition has been achieved without compromising the mass resolution by introducing a field free drift region after the lensing arrangement. The field free interaction region is provided for low energy electron molecule collision studies. The spectrometer can be used to study a wide range of masses (H- ion to few hundreds atomic mass unit). The mass resolution capability of the spectrometer has been checked experimentally by measuring the mass spectra of fragment anions arising from DEA to methanol. Overall performance of the spectrometer has been tested by measuring the absolute DEA cross section of the ground state SO2 molecule, and the results are satisfactory.

  9. Eddy Covariance Measurements Over a Maize Field: The Contribution of Minor Flux Terms to the Energy Balance Gap

    NASA Astrophysics Data System (ADS)

    Smidt, J.; Ingwersen, J.; Streck, T.

    2015-12-01

    The lack of energy balance closure is a long-standing problem in eddy covariance (EC) measurements. The energy balance equation is defined as Rn - G = H + λE, where Rn is net radiation, G is the ground heat flux, H is the sensible heat flux and λE is the latent heat flux. In most cases of energy imbalance, either Rn is overestimated or the ground heat and turbulent fluxes are underestimated. Multiple studies have shown that calculations, incorrect instrument installation/calibration and measurement errors alone do not entirely account for this imbalance. Rather, research is now focused on previously neglected sources of heat storage in the soil, biomass and air beneath the EC station. This project examined the potential of five "minor flux terms" - soil heat storage, biomass heat storage, energy consumption by photosynthesis, air heat storage and atmospheric moisture change, to further close the energy balance gap. Eddy covariance measurements were conducted at a maize (Zea mays) field in southwest Germany during summer 2014. Soil heat storage was measured for six weeks at 11 sites around the field footprint. Biomass and air heat storage were measured for six subsequent weeks at seven sites around the field footprint. Energy consumption by photosynthesis was calculated using the CO2 flux data. Evapotranspiration was calculated using the water balance method and then compared to the flux data processed with three post-closure methods: the sensible heat flux, the latent heat flux and the Bowen ratio post-closure methods. An energy balance closure of 66% was achieved by the EC station measurements over the entire investigation period. During the soil heat flux campaign, EC station closure was 74.1%, and the field footprint soil heat storage contributed 3.3% additional closure. During the second minor flux term measurement period, closure with the EC station data was 91%. Biomass heat storage resulted in 1.1% additional closure, the photosynthesis flux closed the gap

  10. A global algorithm for estimating Absolute Salinity

    NASA Astrophysics Data System (ADS)

    McDougall, T. J.; Jackett, D. R.; Millero, F. J.; Pawlowicz, R.; Barker, P. M.

    2012-12-01

    The International Thermodynamic Equation of Seawater - 2010 has defined the thermodynamic properties of seawater in terms of a new salinity variable, Absolute Salinity, which takes into account the spatial variation of the composition of seawater. Absolute Salinity more accurately reflects the effects of the dissolved material in seawater on the thermodynamic properties (particularly density) than does Practical Salinity. When a seawater sample has standard composition (i.e. the ratios of the constituents of sea salt are the same as those of surface water of the North Atlantic), Practical Salinity can be used to accurately evaluate the thermodynamic properties of seawater. When seawater is not of standard composition, Practical Salinity alone is not sufficient and the Absolute Salinity Anomaly needs to be estimated; this anomaly is as large as 0.025 g kg-1 in the northernmost North Pacific. Here we provide an algorithm for estimating Absolute Salinity Anomaly for any location (x, y, p) in the world ocean. To develop this algorithm, we used the Absolute Salinity Anomaly that is found by comparing the density calculated from Practical Salinity to the density measured in the laboratory. These estimates of Absolute Salinity Anomaly however are limited to the number of available observations (namely 811). In order to provide a practical method that can be used at any location in the world ocean, we take advantage of approximate relationships between Absolute Salinity Anomaly and silicate concentrations (which are available globally).

  11. Estimation of electrical conductivity distribution within the human head from magnetic flux density measurement.

    PubMed

    Gao, Nuo; Zhu, S A; He, Bin

    2005-06-07

    We have developed a new algorithm for magnetic resonance electrical impedance tomography (MREIT), which uses only one component of the magnetic flux density to reconstruct the electrical conductivity distribution within the body. The radial basis function (RBF) network and simplex method are used in the present approach to estimate the conductivity distribution by minimizing the errors between the 'measured' and model-predicted magnetic flux densities. Computer simulations were conducted in a realistic-geometry head model to test the feasibility of the proposed approach. Single-variable and three-variable simulations were performed to estimate the brain-skull conductivity ratio and the conductivity values of the brain, skull and scalp layers. When SNR = 15 for magnetic flux density measurements with the target skull-to-brain conductivity ratio being 1/15, the relative error (RE) between the target and estimated conductivity was 0.0737 +/- 0.0746 in the single-variable simulations. In the three-variable simulations, the RE was 0.1676 +/- 0.0317. Effects of electrode position uncertainty were also assessed by computer simulations. The present promising results suggest the feasibility of estimating important conductivity values within the head from noninvasive magnetic flux density measurements.

  12. Comparison of calculated and measured foliar O3 flux in crop and forest species

    Treesearch

    Nancy Grulke; E. Paoletti; R.L. Heath

    2007-01-01

    We designed a new gas exchange system that concurrently measures foliar H2O, O3, and CO2 flux (HOC flux system) while delivering known O3 concentrations. Stomatal responses of three species were tested: snapbean, and seedlings of California black oak (deciduous broadleaf) and...

  13. Frequency comb calibrated frequency-sweeping interferometry for absolute group refractive index measurement of air.

    PubMed

    Yang, Lijun; Wu, Xuejian; Wei, Haoyun; Li, Yan

    2017-04-10

    The absolute group refractive index of air at 194061.02 GHz is measured in real time using frequency-sweeping interferometry calibrated by an optical frequency comb. The group refractive index of air is calculated from the calibration peaks of the laser frequency variation and the interference signal of the two beams passing through the inner and outer regions of a vacuum cell when the frequency of a tunable external cavity diode laser is scanned. We continuously measure the refractive index of air for 2 h, which shows that the difference between measured results and Ciddor's equation is less than 9.6×10-8, and the standard deviation of that difference is 5.9×10-8. The relative uncertainty of the measured refractive index of air is estimated to be 8.6×10-8. The data update rate is 0.2 Hz, making it applicable under conditions in which air refractive index fluctuates fast.

  14. Absolute surface reconstruction by slope metrology and photogrammetry

    NASA Astrophysics Data System (ADS)

    Dong, Yue

    Developing the manufacture of aspheric and freeform optical elements requires an advanced metrology method which is capable of inspecting these elements with arbitrary freeform surfaces. In this dissertation, a new surface measurement scheme is investigated for such a purpose, which is to measure the absolute surface shape of an object under test through its surface slope information obtained by photogrammetric measurement. A laser beam propagating toward the object reflects on its surface while the vectors of the incident and reflected beams are evaluated from the four spots they leave on the two parallel transparent windows in front of the object. The spots' spatial coordinates are determined by photogrammetry. With the knowledge of the incident and reflected beam vectors, the local slope information of the object surface is obtained through vector calculus and finally yields the absolute object surface profile by a reconstruction algorithm. An experimental setup is designed and the proposed measuring principle is experimentally demonstrated by measuring the absolute surface shape of a spherical mirror. The measurement uncertainty is analyzed, and efforts for improvement are made accordingly. In particular, structured windows are designed and fabricated to generate uniform scattering spots left by the transmitted laser beams. Calibration of the fringe reflection instrument, another typical surface slope measurement method, is also reported in the dissertation. Finally, a method for uncertainty analysis of a photogrammetry measurement system by optical simulation is investigated.

  15. AmeriFlux Measurement Component (AMC) Instrument Handbook

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Reichl, Ken; Biraud, Sebastien C.

    2016-04-01

    An AMC system was installed at the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility North Slope of Alaska (NSA) Barrow site, also known as NSA C1 at the ARM Data Archive, in August 2012. A second AMC system was installed at the third ARM Mobile Facility deployment at Oliktok Point, also known as NSA M1. This in situ system consists of 12 combination soil temperature and volumetric water content (VWC) reflectometers and one set of upwelling and downwelling photosynthetically active radiation (PAR) sensors, all deployed within the fetch of the Eddy Correlation Flux Measurement System.more » Soil temperature and VWC sensors placed at two depths (10 and 30 cm below the vegetation layer) at six locations (or microsites) allow soil property inhomogeneity to be monitored across a landscape.« less

  16. Using "snapshot" measurements of CH4 fluxes from peatlands to estimate annual budgets: interpolation vs. modelling.

    NASA Astrophysics Data System (ADS)

    Green, Sophie M.; Baird, Andy J.

    2016-04-01

    There is growing interest in estimating annual budgets of peatland-atmosphere carbon dioxide (CO2) and methane (CH4) exchanges. Such budgeting is required for calculating peatland carbon balance and the radiative forcing impact of peatlands on climate. There have been multiple approaches used to estimate CO2 budgets; however, there is a limited literature regarding the modelling of annual CH4 budgets. Using data collected from flux chamber tests in an area of blanket peatland in North Wales, we compared annual estimates of peatland-atmosphere CH4 emissions using an interpolation approach and an additive and multiplicative modelling approach. Flux-chamber measurements represent a snapshot of the conditions on a particular site. In contrast to CO2, most studies that have estimated the time-integrated flux of CH4 have not used models. Typically, linear interpolation is used to estimate CH4 fluxes during the time periods between flux-chamber measurements. It is unclear how much error is involved with such a simple integration method. CH4 fluxes generally show a rise followed by a fall through the growing season that may be captured reasonably well by interpolation, provided there are sufficiently frequent measurements. However, day-to-day and week-to-week variability is also often evident in CH4 flux data, and will not necessarily be properly represented by interpolation. Our fits of the CH4 flux models yielded r2 > 0.5 in 38 of the 48 models constructed, with 55% of these having a weighted rw2 > 0.4. Comparison of annualised CH4 fluxes estimated by interpolation and modelling reveals no correlation between the two data sets; indeed, in some cases even the sign of the flux differs. The difference between the methods seems also to be related to the size of the flux - for modest annual fluxes there is a fairly even scatter of points around the 1:1 line, whereas when the modelled fluxes are high, the corresponding interpolated fluxes tend to be low. We consider the

  17. Absolute intensity measurements of impurity emissions in a shock tunnel and their consequences for laser-induced fluorescence experiments

    NASA Technical Reports Server (NTRS)

    Palma, P. C.; Houwing, A. F. P.; Sandeman, R. J.

    1993-01-01

    Absolute intensity measurements of impurity emissions in a shock tunnel nozzle flow are presented. The impurity emission intensities were measured with a photomultiplier and optical multichannel analyzer and calibrated against an intensity standard. The various metallic contaminants were identified and their intensities measured in the spectral regions 290 to 330 nm and 375 to 385 nm. A comparison with calculated fluorescence intensities for predissociated laser-induced fluorescence signals is made. It is found that the emission background is negligible for most fluorescence experiments.

  18. Absolute photoionization cross-section of the methyl radical.

    PubMed

    Taatjes, Craig A; Osborn, David L; Selby, Talitha M; Meloni, Giovanni; Fan, Haiyan; Pratt, Stephen T

    2008-10-02

    The absolute photoionization cross-section of the methyl radical has been measured using two completely independent methods. The CH3 photoionization cross-section was determined relative to that of acetone and methyl vinyl ketone at photon energies of 10.2 and 11.0 eV by using a pulsed laser-photolysis/time-resolved synchrotron photoionization mass spectrometry method. The time-resolved depletion of the acetone or methyl vinyl ketone precursor and the production of methyl radicals following 193 nm photolysis are monitored simultaneously by using time-resolved synchrotron photoionization mass spectrometry. Comparison of the initial methyl signal with the decrease in precursor signal, in combination with previously measured absolute photoionization cross-sections of the precursors, yields the absolute photoionization cross-section of the methyl radical; sigma(CH3)(10.2 eV) = (5.7 +/- 0.9) x 10(-18) cm(2) and sigma(CH3)(11.0 eV) = (6.0 +/- 2.0) x 10(-18) cm(2). The photoionization cross-section for vinyl radical determined by photolysis of methyl vinyl ketone is in good agreement with previous measurements. The methyl radical photoionization cross-section was also independently measured relative to that of the iodine atom by comparison of ionization signals from CH3 and I fragments following 266 nm photolysis of methyl iodide in a molecular-beam ion-imaging apparatus. These measurements gave a cross-section of (5.4 +/- 2.0) x 10(-18) cm(2) at 10.460 eV, (5.5 +/- 2.0) x 10(-18) cm(2) at 10.466 eV, and (4.9 +/- 2.0) x 10(-18) cm(2) at 10.471 eV. The measurements allow relative photoionization efficiency spectra of methyl radical to be placed on an absolute scale and will facilitate quantitative measurements of methyl concentrations by photoionization mass spectrometry.

  19. Airborne boundary layer flux measurements of trace species over Canadian boreal forest and northern wetland regions

    NASA Technical Reports Server (NTRS)

    Ritter, John A.; Barrick, John D. W.; Watson, Catherine E.; Sachse, Glen W.; Gregory, Gerald L.; Anderson, Bruce E.; Woerner, Mary A.; Collins, James E., Jr.

    1994-01-01

    Airborne heat, moisture, O3, CO, and CH4 flux measurements were obtained over the Hudson Bay lowlands (HBL) and northern boreal forest regions of Canada during July - August 1990. The airborne flux measurements were an integral part of the NASA/Arctic Boundary Layer Expedition (ABLE) 3B field experiment executed in collaboration with the Canadian Northern Wetlands Study (NOWES). Airborne CH4 flux measurements were taken over a large portion of the HBL. The surface level flux of CH4 was obtained from downward extrapolations of multiple-level CH4 flux measurements. Methane source strengths ranged from -1 to 31 mg m(exp -2)/d, with the higher values occurring in relatively small, isolated areas. Similar measurements of the CH4 source strength in the boreal forest region of Schefferville, Quebec, ranged from 6 to 27 mg m(exp -2)/d and exhibited a diurnal dependence. The CH4 source strengths found during the ABLE 3B expedition were much lower than the seasonally averaged source strength of 51 mg m(exp -2)/d found for the Yukon-Kuskokwim delta region of Alaska during the previous ABLE 3A study. Large positive CO fluxes (0.31 to 0.53 parts per billion by volume (ppbv) m/s) were observed over the inland, forested regions of the HBL study area, although the mechanism for the generation of these fluxes was not identified. Repetitive measurements along the same ground track at various times of day near the Schefferville site also suggested a diurnal dependence for CO emissions. Measurements of surface resistance to the uptake of O3 (1.91 to 0.80 s/cm) for the HBL areas investigated were comparable to those observed near the Schefferville site (3.40 to 1.10 s/cm). Surface resistance values for the ABLE 3B study area were somewhat less than those observed over the Yukon-Kuskokwim delta during the previous ABLE 3A study. The budgets for heat, moisture, O3, CO, and CH4 were evaluated. The residuals from these budget studies indicated, for the cases selected, a moderate net

  20. Refining Field Measurements of Methane Flux Rates from Abandoned Oil and Gas Wells

    NASA Astrophysics Data System (ADS)

    Lagron, C. S.; Kang, M.; Riqueros, N. S.; Jackson, R. B.

    2015-12-01

    Recent studies in Pennsylvania demonstrate the potential for significant methane emissions from abandoned oil and gas wells. A subset of tested wells was high emitting, with methane flux rates up to seven orders of magnitude greater than natural fluxes (up to 105 mg CH4/hour, or about 2.5LPM). These wells contribute disproportionately to the total methane emissions from abandoned oil and gas wells. The principles guiding the chamber design have been developed for lower flux rates, typically found in natural environments, and chamber design modifications may reduce uncertainty in flux rates associated with high-emitting wells. Kang et al. estimate errors of a factor of two in measured values based on previous studies. We conduct controlled releases of methane to refine error estimates and improve chamber design with a focus on high-emitters. Controlled releases of methane are conducted at 0.05 LPM, 0.50 LPM, 1.0 LPM, 2.0 LPM, 3.0 LPM, and 5.0 LPM, and at two chamber dimensions typically used in field measurements studies of abandoned wells. As most sources of error tabulated by Kang et al. tend to bias the results toward underreporting of methane emissions, a flux-targeted chamber design modification can reduce error margins and/or provide grounds for a potential upward revision of emission estimates.

  1. Carbon fluxes of Kobresia pygmaea pastures on the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Foken, T.; Biermann, T.; Babel, W.; Ma, Y.

    2013-12-01

    With an approximate cover of 450,000 km2 on the Tibetan Plateau (TP), the Cyperaceae Kobresia pygmaea forms he world's largest alpine ecosystem. This species, especially adapted to grazing pressure, grows to a height of only 2-6 cm and can be found in an altitudinal range of 4000 to 5960 m a.s.l. A special characteristic of this ecosystem is the stable turf layer, which is built up from roots and plays a significant role in protecting soil from erosion. This is of great importance since soils on the TP store 2.5 % of the global soil organic carbon stocks. The aim of the investigation was the study of the carbon storage and the impact of human-induced land use change on these Kobresia pygmaea pastures. We therefore applied eddy-covariance measurements and modelling as a long-term control of the fluxes between the atmosphere and the pastures and 13C labelling for the investigation of flux partitioning, and chamber measurements to investigate the degradation of the pastures. Combining CO2 budgets observed in 2010 with eddy-covariance measurements and relative partitioning of Carbon fluxes estimated with 13C labelling enabled us to characterise the C turnover for the vegetation period with absolute fluxes within the plant-soil-atmosphere continuum. These results revealed that this ecosystem indeed stores a great amount of C in below-ground pools, especially in the root turf layer. To further investigate the importance of the root layer, the experiments in 2012 focused on flux measurements over the different surface types which make up the heterogeneity of the Kobresia pygmaea pastures and might result from degradation due to extensive grazing. The three surface types investigated with a LiCOR long-term monitoring chamber system include Kobresia pygmaea with intact turf layer (IRM), a surface type where the turf layer is still present but the vegetation is sparse and mainly consists of Cryptogam crusts (DRM) and finally areas without the turf layer (BS). According to

  2. AmeriFlux Measurement Component (AMC) Handbook

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Reichl, K.; Biraud, S. C.

    An AMC system was installed at the Atmospheric Radiation Measurement (ARM) Climate Research Facility’s North Slope Alaska (NSA) Barrow site, also known as NSA C1 at the ARM Data Archive, in August 2012. A second AMC system was installed at the third ARM Mobile Facility deployment at Oliktok Point, also known as NSA M1. This in situ system consists of 12 combination soil temperature and volumetric water content (VWC) reflectometers and one set of upwelling and downwelling PAR sensors, all deployed within the fetch of the Eddy Correlation Flux Measurement System. Soil temperature and VWC sensors placed at two depthsmore » (10 and 30 cm below the vegetation layer) at six locations (or microsites) allow soil property inhomogeneity to be monitored across a landscape. The soil VWC and temperature sensors used at NSA C1 are the Campbell Scientific CS650L and the sensors at NSA M1 use the Campbell Scientific CS655. The two sensors are nearly identical in function, and vendor specifications are based on the CS650 unless otherwise stated.« less

  3. Thermal neutron flux measurement using self-powered neutron detector (SPND) at out-core locations of TRIGA PUSPATI Reactor (RTP)

    NASA Astrophysics Data System (ADS)

    Ali, Nur Syazwani Mohd; Hamzah, Khaidzir; Mohamad Idris, Faridah; Hairie Rabir, Mohamad

    2018-01-01

    The thermal neutron flux measurement has been conducted at the out-core location using self-powered neutron detectors (SPNDs). This work represents the first attempt to study SPNDs as neutron flux sensor for developing the fault detection system (FDS) focusing on neutron flux parameters. The study was conducted to test the reliability of the SPND’s signal by measuring the neutron flux through the interaction between neutrons and emitter materials of the SPNDs. Three SPNDs were used to measure the flux at four different radial locations which located at the fission chamber cylinder, 10cm above graphite reflector, between graphite reflector and tank liner and fuel rack. The measurements were conducted at 750 kW reactor power. The outputs from SPNDs were collected through data acquisition system and were corrected to obtain the actual neutron flux due to delayed responses from SPNDs. The measurements showed that thermal neutron flux between fission chamber location near to the tank liner and fuel rack were between 5.18 × 1011 nv to 8.45 × 109 nv. The average thermal neutron flux showed a good agreement with those from previous studies that has been made using simulation at the same core configuration at the nearest irradiation facilities with detector locations.

  4. A novel multi-dimensional absolute distance measurement system using a basic frequency modulated continuous wave radar and an external cavity laser with trilateration metrology

    NASA Astrophysics Data System (ADS)

    Xiong, Xingting; Qu, Xinghua; Zhang, Fumin

    2018-01-01

    We propose and describe a novel multi-dimensional absolute distance measurement system. This system incorporates a basic frequency modulated continuous wave (FMCW) radar and an second external cavity laser (ECL). Through the use of trilateration, the system in our paper can provide 3D resolution inherently range. However, the measured optical path length differences (OPD) is often variable in industrial environments and this will causes Doppler effect, which has greatly impact on the measurement result. With using the second ECL, the system can correct the Doppler effect to ensure the precision of absolute distance measurement. Result of the simulation will prove the influence of Doppler effect.

  5. Suspended sediment fluxes in a tidal wetland: Measurement, controlling factors, and error analysis

    USGS Publications Warehouse

    Ganju, N.K.; Schoellhamer, D.H.; Bergamaschi, B.A.

    2005-01-01

    Suspended sediment fluxes to and from tidal wetlands are of increasing concern because of habitat restoration efforts, wetland sustainability as sea level rises, and potential contaminant accumulation. We measured water and sediment fluxes through two channels on Browns Island, at the landward end of San Francisco Bay, United States, to determine the factors that control sediment fluxes on and off the island. In situ instrumentation was deployed between October 10 and November 13, 2003. Acoustic Doppler current profilers and the index velocity method were employed to calculate water fluxes. Suspended sediment concentrations (SSC) were determined with optical sensors and cross-sectional water sampling. All procedures were analyzed for their contribution to total error in the flux measurement. The inability to close the water balance and determination of constituent concentration were identified as the main sources of error; total error was 27% for net sediment flux. The water budget for the island was computed with an unaccounted input of 0.20 m 3 s-1 (22% of mean inflow), after considering channel flow, change in water storage, evapotranspiration, and precipitation. The net imbalance may be a combination of groundwater seepage, overland flow, and flow through minor channels. Change of island water storage, caused by local variations in water surface elevation, dominated the tidalty averaged water flux. These variations were mainly caused by wind and barometric pressure change, which alter regional water levels throughout the Sacramento-San Joaquin River Delta. Peak instantaneous ebb flow was 35% greater than peak flood flow, indicating an ebb-dominant system, though dominance varied with the spring-neap cycle. SSC were controlled by wind-wave resuspension adjacent to the island and local tidal currents that mobilized sediment from the channel bed. During neap tides sediment was imported onto the island but during spring tides sediment was exported because the main

  6. Measurement of the Nonlinearity of Heat-Flux Sensors Employing a CO_2 laser

    NASA Astrophysics Data System (ADS)

    van der Ham, E. W. M.; Beer, C. M.; Ballico, M. J.

    2018-01-01

    Heat-flux sensors are widely used in industry to test building products and designs for resistance to bushfire, to test the flammability of textiles and in numerous applications such as concentrated solar collectors. In Australia, such detectors are currently calibrated by the National Measurement Institute Australia (NMIA) at low flux levels of 20 W \\cdot m^{-2}. Estimates of the uncertainty arising from nonlinearity at industrial levels (e.g. 50 kW \\cdot m^{-2} for bushfire testing) rely on literature information. NMIA has developed a facility to characterize the linearity response of these heat-flux sensors up to 110 kW \\cdot m^{-2} using a low-power CO_2 laser and a chopped quartz tungsten-halogen lamp. The facility was validated by comparison with the conventional flux-addition method, and used to characterize several Schmidt-Boelter-type sensors. A significant nonlinear response was found, ranging from (3.2 ± 0.9)% at 40 kW \\cdot m^{-2} to more than 8 % at 100 kW \\cdot m^{-2}. Additional measurements confirm that this is not attributable to convection effects, but due to the temperature dependence of the sensor's responsivity.

  7. Fluxes of Submicron Organic Aerosol above London Measured by Eddy Covariance using the Aerodyne HR-ToF-AMS

    NASA Astrophysics Data System (ADS)

    Phillips, G. J.; di Marco, C. F.; Farmer, D.; Kimmel, J. R.; Jimenez, J. L.; Nemitz, E.

    2009-12-01

    Urban centres are large sources of sub-micron particles. The myriad of emission sources combined with the complex interaction between regional aerosol and the particulate and gaseous photochemistry make for a complex system. It is evident that particulate emissions from cities will affect the regional atmosphere as well as the environment within the urban area. Aerosol particles have been associated with respiratory and cardio-vascular disease and are also linked with the climate through scattering of radiation and indirect effects such as cloud formation. The Aerodyne Aerosol Mass Spectrometer (AMS) provides a powerful tool to elucidate the sources and processing of organic aerosol in the urban atmosphere. Normally this is done through concentration measurements, by statistical analysis of the organic mass spectra, e.g. using Positive Matrix Factorization (PMF). Recently the quadrupole based AMS (Q-AMS) has been used for the micrometeorological measurement of organic aerosol fluxes above several cities, based on high frequency measurements of individual masses (m/z) representative of different organic mass fractions. While providing a major step forward towards quantification of urban organic aerosol emissions and processing, the interpretation of Q-AMS flux data requires assumptions to scale up signals on individual m/z to total organic mass fluxes. In this paper we present chemically-speciated and size-segregated number aerosol fluxes measured using the next generation eddy covariance flux system based on the Aerodyne HR-ToF-AMS, now capable of recording fast-response eddy-covariance time-series of all m/z simultaneously. This allows organic mass fluxes to be calculated more quantitatively and provides 'flux mass spectra' in addition to concentration mass spectra, which produces novel information on the local emission and processing of organic aerosols in the urban environment, while concentration analysis includes the regional background. The measurements were

  8. The measurable heat flux that accompanies active transport by Ca2+-ATPase.

    PubMed

    Bedeaux, Dick; Kjelstrup, Signe

    2008-12-28

    We present a new mesoscopic basis which can be used to derive flux equations for the forward and reverse mode of operation of ion-pumps. We obtain a description of the fluxes far from global equilibrium. An asymmetric set of transport coefficients is obtained, by assuming that the chemical reaction as well as the ion transports are activated, and that the enzyme has a temperature independent of the activation coordinates. Close to global equilibrium, the description reduces to the well known one from non-equilibrium thermodynamics with a symmetric set of transport coefficients. We show how the measurable heat flux and the heat production under isothermal conditions, as well as thermogenesis, can be defined. Thermogenesis is defined via the onset of the chemical reaction or ion transports by a temperature drop. A prescription has been given for how to determine transport coefficients on the mesocopic level, using the macroscopic coefficient obtained from measurements, the activation enthalpy, and a proper probability distribution. The method may give new impetus to a long-standing unsolved transport problem in biophysics.

  9. Uncertainty analysis of scintillometers methods in measuring sensible heat fluxes of forest ecosystem

    NASA Astrophysics Data System (ADS)

    Zheng, N.

    2017-12-01

    Sensible heat flux (H) is one of the driving factors of surface turbulent motion and energy exchange. Therefore, it is particularly important to measure sensible heat flux accurately at the regional scale. However, due to the heterogeneity of the underlying surface, hydrothermal regime, and different weather conditions, it is difficult to estimate the represented flux at the kilometer scale. The scintillometer have been developed into an effective and universal equipment for deriving heat flux at the regional-scale which based on the turbulence effect of light in the atmosphere since the 1980s. The parameter directly obtained by the scintillometer is the structure parameter of the refractive index of air based on the changes of light intensity fluctuation. Combine with parameters such as temperature structure parameter, zero-plane displacement, surface roughness, wind velocity, air temperature and the other meteorological data heat fluxes can be derived. These additional parameters increase the uncertainties of flux because the difference between the actual feature of turbulent motion and the applicable conditions of turbulence theory. Most previous studies often focused on the constant flux layers that are above the rough sub-layers and homogeneous flat surfaces underlying surfaces with suitable weather conditions. Therefore, the criteria and modified forms of key parameters are invariable. In this study, we conduct investment over the hilly area of northern China with different plants, such as cork oak, cedar-black and locust. On the basis of key research on the threshold and modified forms of saturation with different turbulence intensity, modified forms of Bowen ratio with different drying-and-wetting conditions, universal function for the temperature structure parameter under different atmospheric stability, the dominant sources of uncertainty will be determined. The above study is significant to reveal influence mechanism of uncertainty and explore influence

  10. Estimating Energy Expenditure Using Heat Flux Measured at Single Body Site

    PubMed Central

    Lyden, Kate; Swibas, Tracy; Catenacci, Victoria; Guo, Ruixin; Szuminsky, Neil; Melanson, Edward L.

    2014-01-01

    Introduction The Personal Calorie Monitor (PCM) is a portable direct calorimeter that estimates energy expenditure (EE) from measured heat flux (i.e. the sum of conductive, convective, radiative, and evaporative). Purpose The primary aim of this study was to compare EE estimated from measures of heat flux to indirect calorimetry in a thermoneutral environment (26°C). A secondary aim was to determine if exposure to ambient temperature below thermoneutral (19°C) influences the accuracy of the PCM. Methods 34 Adults (mean±SD, age = 28±5 y, body mass index = 22.9±2.6 kg.m2) were studied for 5 h in a whole-room indirect calorimeter (IC) in thermoneutral and cool conditions. Participants wore the PCM on their upper arm and completed two, 20-minute treadmill-walking bouts (0% grade, 3 mph). The remaining time was spent sedentary (e.g., watching television, using a computer). Results In thermoneutral, EE (mean (95% CI)) measured by IC and PCM was 560.0 (526.5, 593.5) and 623.3 (535.5, 711.1) kcals, respectively. In cool, EE measured by IC and PCM was 572.5 (540.9, 604.0) and 745.5 (668.1, 822.8) kcals, respectively. Under thermoneutral conditions, mean PCM minute-by-minute EE tracked closely with IC, resulting in a small, non-significant bias (63 kcals (−5.8, 132.4)). During cool conditions, mean PCM minute-by-minute EE did not track IC, resulting in a large bias (173.0 (93.9, 252.1)) (p<0.001). Conclusion This study demonstrated the validity of using measured heat flux to estimate EE. However, accuracy may be impaired in cool conditions, possibly due to excess heat loss from the exposed limbs. PMID:24811326

  11. Long-term elemental dry deposition fluxes measured around Lake Michigan with an automated dry deposition sampler

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shahin, U. Yi, S.M.; Paode, R.D.; Holsen, T.M.

    2000-05-15

    Long-term measurements of mass and elemental dry deposition (MG, Al, V, Cr, Mn, Ni, Co, Cu, Zn, As, Sr, Mo, Cd, Sb, Ba, and Pb) were made with an automated dry deposition sampler (Eagle II) containing knife-edge surrogate surfaces during the Lake Michigan Mass Balance/Mass Budget Study. Measurements were made over a roughly 700-day period in Chicago, IL; in South Haven and Sleeping Bear Dunes, MI; and over Lake Michigan on the 68th Street drinking water intake cribs from December 1993 to October 1995. Average mass fluxes in Chicago, South Haven, Sleeping Bear Dunes, and the 68th Street crib weremore » 65, 10, 3.6, and 12 mg m{sup {minus}2} day{sup {minus}1}, respectively. Primarily crustal elemental fluxes were significantly smaller than the mass fluxes but higher than primarily anthropogenic elemental fluxes. For example, the average elemental flux of Al in Chicago, South Haven, Sleeping Bear Dunes, and the 68th Street crib were 1.0, 0.34, 0.074, and 0.34 mg m{sup {minus}2}day{sup {minus}1}, respectively. The average Pb fluxes in Chicago, South Haven, Sleeping Bear Dunes, and the 68th Street crib were 0.038, 0.023, 0.035, and 0.032 mg m{sup {minus}2}day{sup {minus}1}, respectively. The measured fluxes at the various sites were used to calculate the dry deposition loadings to the lake. These estimated fluxes were highest for Mg and lowest for Cd.« less

  12. Measurement uncertainties in quantifying aeolian mass flux: evidence from wind tunnel and field site data

    PubMed Central

    Keijsers, Joep G.S.; Maroulis, Jerry; Visser, Saskia M.

    2014-01-01

    Aeolian sediment traps are widely used to estimate the total volume of wind-driven sediment transport, but also to study the vertical mass distribution of a saltating sand cloud. The reliability of sediment flux estimations from such measurements are dependent upon the specific configuration of the measurement compartments and the analysis approach used. In this study, we analyse the uncertainty of these measurements by investigating the vertical cumulative distribution and relative sediment flux derived from both wind tunnel and field studies. Vertical flux data was examined using existing data in combination with a newly acquired dataset; comprising meteorological data and sediment fluxes from six different events, using three customized catchers at Ameland beaches in northern Netherlands. Fast-temporal data collected in a wind tunnel shows that the median transport height has a scattered pattern between impact and fluid threshold, that increases linearly with shear velocities above the fluid threshold. For finer sediment, a larger proportion was transported closer to the surface compared to coarser sediment fractions. It was also shown that errors originating from the distribution of sampling compartments, specifically the location of the lowest sediment trap relative to the surface, can be identified using the relative sediment flux. In the field, surface conditions such as surface moisture, surface crusts or frozen surfaces have a more pronounced but localized effect than shear velocity. Uncertainty in aeolian mass flux estimates can be reduced by placing multiple compartments in closer proximity to the surface. PMID:25071984

  13. High CO2 emissions through porous media: Transport mechanisms and implications for flux measurement and fractionation

    USGS Publications Warehouse

    Evans, William C.; Sorey, M.L.; Kennedy, B.M.; Stonestrom, David A.; Rogie, J.D.; Shuster, D.L.

    2001-01-01

    Diffuse emissions of CO2 are known to be large around some volcanoes and hydrothermal areas. Accumulation-chamber measurements of CO2 flux are increasingly used to estimate the total magmatic or metamorphic CO2 released from such areas. To assess the performance of accumulation chamber systems at fluxes one to three orders of magnitude higher than normally encountered in soil respiration studies, a test system was constructed in the laboratory where known fluxes could be maintained through dry sand. Steady-state gas concentration profiles and fractionation effects observed in the 30-cm sand column nearly match those predicted by the Stefan-Maxwell equations, indicating that the test system was functioning successfully as a uniform porous medium. Eight groups of investigators tested their accumulation chamber equipment, all configured with continuous infrared gas analyzers (IRGA), in this system. Over a flux range of ~ 200-12,000 g m-2 day-1, 90% of their 203 flux measurements were 0-25% lower than the imposed flux with a mean difference of - 12.5%. Although this difference would seem to be within the range of acceptability for many geologic investigations, some potential sources for larger errors were discovered. A steady-state pressure gradient of -20 Pa/m was measured in the sand column at a flux of 11,200 g m-2 day-1. The derived permeability (50 darcies) was used in the dusty-gas model (DGM) of transport to quantify various diffusive and viscous flux components. These calculations were used to demonstrate that accumulation chambers, in addition to reducing the underlying diffusive gradient, severely disrupt the steady-state pressure gradient. The resultant diversion of the net gas flow is probably responsible for the systematically low flux measurements. It was also shown that the fractionating effects of a viscous CO2 efflux against a diffusive influx of air will have a major impact on some important geochemical indicators, such as N2/Ar, ??15N-N2, and 4He/22

  14. Four-year measurement of methane flux over a temperate forest with a relaxed eddy accumulation method

    NASA Astrophysics Data System (ADS)

    Sakabe, A.; Kosugi, Y.; Ueyama, M.; Hamotani, K.; Takahashi, K.; Iwata, H.; Itoh, M.

    2013-12-01

    Forests are generally assumed to be an atmospheric methane (CH4) sink (Le Mer and Roger, 2001). However, under Asian monsoon climate, forests are subject to wide spatiotemporal range in soil water status, where forest soils often became water-saturated condition heterogeneously. In such warm and humid conditions, forests may act as a CH4 source and/or sink with considerable spatiotemporal variations. Micrometeorological methods such as eddy covariance (EC) method continuously measure spatially-representative flux at a canopy scale without artificial disturbance. In this study, we measured CH4 fluxes over a temperate forest during four-year period using a CH4 analyzer based on tunable diode laser spectroscopy detection with a relaxed eddy accumulation (REA) method (Hamotani et al., 1996, 2001). We revealed the amplitude and seasonal variations of canopy-scale CH4 fluxes. The REA method is the attractive alternative to the EC method to measure trace-gas flux because it allows the use of analyzers with an optimal integration time. We also conducted continuous chamber measurements on forest floor to reveal spatial variations in soil CH4 fluxes and its controlling processes. The observations were made in an evergreen coniferous forest in central Japan. The site has a warm temperate monsoon climate with wet summer. Some wetlands were located in riparian zones along streams within the flux footprint area. For the REA method, the sonic anemometer (SAT-550, Kaijo) was mounted on top of the 29-m-tall tower and air was sampled from just below the sonic anemometer to reservoirs according to the direction of vertical wind velocity (w). After accumulating air for 30 minutes, the air in the reservoirs was pulled into a CO2/H2O gas analyzer (LI-840, Li-Cor) and a CH4 analyzer (FMA-200, Los Gatos Research). Before entering the analyzers, the sampled air was dried using a gas dryer (PD-50 T-48; Perma Pure Inc.). The REA flux is obtained from the difference in the mean concentrations

  15. Role of plant-generated water vapor and VOC fluxes in shoot chamber measurements of O3 and NOx

    NASA Astrophysics Data System (ADS)

    Joensuu, J.; Altimir, N.; Raivonen, M.; Kolari, P.; Keronen, P.; Vesala, T.; Bäck, J.; Hari, P.; Järvinen, E.; Nikinmaa, E.

    2012-04-01

    One of the processes underlying the atmospheric balance of O3 and NOx is their interaction with vegetation. Both are removed, absorbed, and NOx potentially also emitted by foliage. Uncertainties remain on relevant factors controlling O3 and NOx interactions with foliage as well as on including them in large-scale models. One reason for the uncertainty is that chamber measurements of O3 and NOx fluxes are complicated. These reactive gases are adsorbed and desorbed on the chamber walls, depending on the conditions (i.e. humidity). These artefact gas fluxes (chamber blank) must also be quantified and taken into account in the data analysis. Their importance increases when measuring in clean air, where the fluxes are generally small. At near-zero concentrations, the fluxes may not pass the detection limit of the instrumentation, which usually means it is not possible to separate the plant-related fluxes from the chamber blank. The long-term field measurements at the SMEAR II station in Hyytiälä, Southern Finland, have provided valuable insights into O3 and NOx exchange (i.e. Raivonen & al. 2009, Altimir & al. 2006). This project builds up on the expertise and conclusions from these works. The aim of this study was to improve the reliability of the measuring system by checking the role of potential measuring artefact(s). A live shoot, enclosed in a chamber, creates a water vapor in the chamber flux by transpiring. There are also biogenic VOC emissions from the shoot. In principle, these may affect the reactions of O3 and possibly NOx in the chamber. The potential interference of these fluxes created naturally during chamber closure is a main concern. Their effect on the O3 and NOx flux measurements has been tested with field calibrations in 2010-2011. In these calibrations, a controlled water vapor /VOC flux was fed into an empty shoot measurement chamber, and the H2O, CO2, O3 and NOx fluxes created in the chamber were measured. The created water vapor flux pattern

  16. Measurement of the absolute branching ratio of the K+ →π+π-π+ (γ) decay with the KLOE detector

    NASA Astrophysics Data System (ADS)

    Babusci, D.; Balwierz-Pytko, I.; Bencivenni, G.; Bloise, C.; Bossi, F.; Branchini, P.; Budano, A.; Caldeira Balkeståhl, L.; Ceradini, F.; Ciambrone, P.; Curciarello, F.; Czerwiński, E.; Danè, E.; De Leo, V.; De Lucia, E.; De Robertis, G.; De Santis, A.; De Simone, P.; Di Cicco, A.; Di Domenico, A.; Di Salvo, R.; Domenici, D.; Erriquez, O.; Fanizzi, G.; Fantini, A.; Felici, G.; Fiore, S.; Franzini, P.; Gajos, A.; Gauzzi, P.; Giardina, G.; Giovannella, S.; Graziani, E.; Happacher, F.; Heijkenskjöld, L.; Höistad, B.; Johansson, T.; Kamińska, D.; Krzemien, W.; Kupsc, A.; Lee-Franzini, J.; Loddo, F.; Loffredo, S.; Mandaglio, G.; Martemianov, M.; Martini, M.; Mascolo, M.; Messi, R.; Miscetti, S.; Morello, G.; Moricciani, D.; Moskal, P.; Palladino, A.; Passeri, A.; Patera, V.; Prado Longhi, I.; Ranieri, A.; Santangelo, P.; Sarra, I.; Schioppa, M.; Sciascia, B.; Silarski, M.; Tortora, L.; Venanzoni, G.; Wiślicki, W.; Wolke, M.; KLOE/KLOE-2 Collaboration

    2014-11-01

    The absolute branching ratio of the K+ →π+π-π+ (γ) decay, inclusive of final-state radiation, has been measured using ∼17 million tagged K+ mesons collected with the KLOE detector at DAΦNE, the Frascati ϕ-factory. The result is:

  17. Absolute calibration of neutron detectors on the C-2U advanced beam-driven FRC

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Magee, R. M., E-mail: rmagee@trialphaenergy.com; Clary, R.; Korepanov, S.

    2016-11-15

    In the C-2U fusion energy experiment, high power neutral beam injection creates a large fast ion population that sustains a field-reversed configuration (FRC) plasma. The diagnosis of the fast ion pressure in these high-performance plasmas is therefore critical, and the measurement of the flux of neutrons from the deuterium-deuterium (D-D) fusion reaction is well suited to the task. Here we describe the absolute, in situ calibration of scintillation neutron detectors via two independent methods: firing deuterium beams into a high density gas target and calibration with a 2 × 10{sup 7} n/s AmBe source. The practical issues of each methodmore » are discussed and the resulting calibration factors are shown to be in good agreement. Finally, the calibration factor is applied to C-2U experimental data where the measured neutron rate is found to exceed the classical expectation.« less

  18. Plastic scintillator detector for pulsed flux measurements

    NASA Astrophysics Data System (ADS)

    Kadilin, V. V.; Kaplun, A. A.; Taraskin, A. A.

    2017-01-01

    A neutron detector, providing charged particle detection capability, has been designed. The main purpose of the detector is to measure pulsed fluxes of both charged particles and neutrons during scientific experiments. The detector consists of commonly used neutron-sensitive ZnS(Ag) / 6LiF scintillator screens wrapping a layer of polystyrene based scintillator (BC-454, EJ-254 or equivalent boron loaded plastic). This type of detector design is able to log a spatial distribution of events and may be scaled to any size. Different variations of the design were considered and modelled in specialized toolkits. The article presents a review of the detector design features as well as simulation results.

  19. Inter-satellite calibration of FengYun 3 medium energy electron fluxes with POES electron measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Ni, Binbin; Xiang, Zheng; Zhang, Xianguo; Zhang, Xiaoxin; Gu, Xudong; Fu, Song; Cao, Xing; Zou, Zhengyang

    2018-05-01

    We perform an L-shell dependent inter-satellite calibration of FengYun 3 medium energy electron measurements with POES measurements based on rough orbital conjunctions within 5 min × 0.1 L × 0.5 MLT. By comparing electron flux data between the U.S. Polar Orbiting Environmental Satellites (POES) and Chinese sun-synchronous satellites including FY-3B and FY-3C for a whole year of 2014, we attempt to remove less reliable data and evaluate systematic uncertainties associated with the FY-3B and FY-3C datasets, expecting to quantify the inter-satellite calibration factors for the 150-350 keV energy channel at L = 2-7. Compared to the POES data, the FY-3B and FY-3C data generally exhibit a similar trend of electron flux variations but more or less underestimate them within a factor of 5 for the medium electron energy 150-350 keV channel. Good consistency in the flux conjunctions after the inter-calibration procedures gives us certain confidence to generalize our method to calibrate electron flux measurements from various satellite instruments.

  20. Development of a laser remote sensing instrument to measure sub-aerial volcanic CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Queisser, Manuel; Burton, Mike

    2016-04-01

    A thorough quantification of volcanic CO2 fluxes would lead to an enhanced understanding of the role of volcanoes in the geological carbon cycle. This would enable a more subtle understanding of human impact on that cycle. Furthermore, variations in volcanic CO2 emissions are a key to understanding volcanic processes such as eruption phenomenology. However, measuring fluxes of volcanic CO2 is challenging as volcanic CO2 concentrations are modest compared with the ambient CO2 concentration (~400 ppm) . Volcanic CO2 quickly dilutes with the background air. For Mt. Etna (Italy), for instance, 1000 m downwind from the crater, dispersion modelling yields a signal of ~4 ppm only. It is for this reason that many magmatic CO2 concentration measurements focus on in situ techniques, such as direct sampling Giggenbach bottles, chemical sensors, IR absorption spectrometers or mass spectrometers. However, emission rates are highly variable in time and space. Point measurements fail to account for this variability. Inferring 1-D or 2-D gas concentration profiles, necessary to estimate gas fluxes, from point measurements may thus lead to erroneous flux estimations. Moreover, in situ probing is time consuming and, since many volcanoes emit toxic gases and are dangerous as mountains, may raise safety concerns. In addition, degassing is often diffuse and spatially extended, which makes a measurement approach with spatial coverage desirable. There are techniques that allow to indirectly retrieve CO2 fluxes from correlated SO2 concentrations and fluxes. However, they still rely on point measurements of CO2 and are prone to errors of SO2 fluxes due to light dilution and depend on blue sky conditions. Here, we present a new remote sensing instrument, developed with the ERC project CO2Volc, which measures 1-D column amounts of CO2 in the atmosphere with sufficient sensitivity to reveal the contribution of magmatic CO2. Based on differential absorption LIDAR (DIAL) the instrument measures