WorldWideScience

Sample records for flux science

  1. AmeriFlux Measurement Network: Science Team Research

    Energy Technology Data Exchange (ETDEWEB)

    Law, B E

    2012-12-12

    Research involves analysis and field direction of AmeriFlux operations, and the PI provides scientific leadership of the AmeriFlux network. Activities include the coordination and quality assurance of measurements across AmeriFlux network sites, synthesis of results across the network, organizing and supporting the annual Science Team Meeting, and communicating AmeriFlux results to the scientific community and other users. Objectives of measurement research include (i) coordination of flux and biometric measurement protocols (ii) timely data delivery to the Carbon Dioxide Information and Analysis Center (CDIAC); and (iii) assurance of data quality of flux and ecosystem measurements contributed by AmeriFlux sites. Objectives of integration and synthesis activities include (i) integration of site data into network-wide synthesis products; and (ii) participation in the analysis, modeling and interpretation of network data products. Communications objectives include (i) organizing an annual meeting of AmeriFlux investigators for reporting annual flux measurements and exchanging scientific information on ecosystem carbon budgets; (ii) developing focused topics for analysis and publication; and (iii) developing data reporting protocols in support of AmeriFlux network goals.

  2. Flux

    DEFF Research Database (Denmark)

    Ravn, Ib

    . FLUX betegner en flyden eller strømmen, dvs. dynamik. Forstår man livet som proces og udvikling i stedet for som ting og mekanik, får man et andet billede af det gode liv end det, som den velkendte vestlige mekanicisme lægger op til. Dynamisk forstået indebærer det gode liv den bedst mulige...... kanalisering af den flux eller energi, der strømmer igennem os og giver sig til kende i vore daglige aktiviteter. Skal vores tanker, handlinger, arbejde, samvær og politiske liv organiseres efter stramme og faste regelsæt, uden slinger i valsen? Eller skal de tværtimod forløbe ganske uhindret af regler og bånd...

  3. Detecting Upward Directed Charged Particle Fluxes in the Mars Science Laboratory Radiation Assessment Detector

    Science.gov (United States)

    Appel, J. K.; Köehler, J.; Guo, J.; Ehresmann, B.; Zeitlin, C.; Matthiä, D.; Lohf, H.; Wimmer-Schweingruber, R. F.; Hassler, D.; Brinza, D. E.; Böhm, E.; Böttcher, S.; Martin, C.; Burmeister, S.; Reitz, G.; Rafkin, S.; Posner, A.; Peterson, J.; Weigle, G.

    2018-01-01

    The Mars Science Laboratory rover Curiosity, operating on the surface of Mars, is exposed to radiation fluxes from above and below. Galactic Cosmic Rays travel through the Martian atmosphere, producing a modified spectrum consisting of both primary and secondary particles at ground level. These particles produce an upward directed secondary particle spectrum as they interact with the Martian soil. Here we develop a method to distinguish the upward and downward directed particle fluxes in the Radiation Assessment Detector (RAD) instrument, verify it using data taken during the cruise to Mars, and apply it to data taken on the Martian surface. We use a combination of Geant4 and Planetocosmics modeling to find discrimination criteria for the flux directions. After developing models of the cruise phase and surface shielding conditions, we compare model-predicted values for the ratio of upward to downward flux with those found in RAD observation data. Given the quality of available information on Mars Science Laboratory spacecraft and rover composition, we find generally reasonable agreement between our models and RAD observation data. This demonstrates the feasibility of the method developed and tested here. We additionally note that the method can also be used to extend the measurement range and capabilities of the RAD instrument to higher energies.

  4. Panel session: Part 1, In flux -- Science Policy and the social structure of Big Laboratories, 1964--1979

    Energy Technology Data Exchange (ETDEWEB)

    Westfall, C. [Michigan State Univ., East Lansing, MI (United States)]|[CEBAF, Newport News, VA (United States)]|[Fermilab History Collaboration, Batavia, IL (United States)

    1993-09-01

    This report discusses the in flux of science policy and the social structure of big laboratories during the period of 1964 to 1979 and some sociological consequences of high energy physicists` development of the standard model during the same period.

  5. Science in Flux: NASA's Nuclear Program at Plum Brook Station 1955-2005

    Science.gov (United States)

    Bowles, Mark D.

    2006-01-01

    Science in Flux traces the history of one of the most powerful nuclear test reactors in the United States and the only nuclear facility ever built by NASA. In the late 1950's NASA constructed Plum Brook Station on a vast tract of undeveloped land near Sandusky, Ohio. Once fully operational in 1963, it supported basic research for NASA's nuclear rocket program (NERVA). Plum Brook represents a significant, if largely forgotten, story of nuclear research, political change, and the professional culture of the scientists and engineers who devoted their lives to construct and operate the facility. In 1973, after only a decade of research, the government shut Plum Brook down before many of its experiments could be completed. Even the valiant attempt to redefine the reactor as an environmental analysis tool failed, and the facility went silent. The reactors lay in costly, but quiet standby for nearly a quarter-century before the Nuclear Regulatory Commission decided to decommission the reactors and clean up the site. The history of Plum Brook reveals the perils and potentials of that nuclear technology. As NASA, Congress, and space enthusiasts all begin looking once again at the nuclear option for sending humans to Mars, the echoes of Plum Brook's past will resonate with current policy and space initiatives.

  6. DCS - A high flux beamline for time resolved dynamic compression science – Design highlights

    International Nuclear Information System (INIS)

    Capatina, D.; D’Amico, K.; Nudell, J.; Collins, J.; Schmidt, O.

    2016-01-01

    The Dynamic Compression Sector (DCS) beamline, a national user facility for time resolved dynamic compression science supported by the National Nuclear Security Administration (NNSA) of the Department of Energy (DOE), has recently completed construction and is being commissioned at Sector 35 of the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The beamline consists of a First Optics Enclosure (FOE) and four experimental enclosures. A Kirkpatrick–Baez focusing mirror system with 2.2 mrad incident angles in the FOE delivers pink beam to the experimental stations. A refocusing Kirkpatrick–Baez mirror system is situated in each of the two most downstream enclosures. Experiments can be conducted in either white, monochromatic, pink or monochromatic-reflected beam mode in any of the experimental stations by changing the position of two interlocked components in the FOE. The beamline Radiation Safety System (RSS) components have been designed to handle the continuous beam provided by two in-line revolver undulators with periods of 27 and 30 mm, at closed gap, 150 mA beam current, and passing through a power limiting aperture of 1.5 x 1.0 mm 2 . A novel pink beam end station stop [1] is used to stop the continuous and focused pink beam which can achieve a peak heat flux of 105 kW/mm 2 . A new millisecond shutter design [2] is used to deliver a quick pulse of beam to the sample, synchronized with the dynamic event, the microsecond shutter, and the storage ring clock.

  7. The flux and reflux of science: The study of the tides and the organization of early Victorian science

    Science.gov (United States)

    Reidy, Michael Sean

    2000-07-01

    For a fortnight in June, 1835, nine countries observed simultaneously the oceanic tides bordering their countries and their possessions. Over 650 tidal stations participated. This multi-national venture, which William Whewell affirmed to include the most ``multiplied and extensive observations yet encountered in science,'' was prototypical of what Susan Faye Cannon has termed ``Humboldtian science.'' This dissertation demonstrates how the beginnings of the politics of imperialism, the economics of a worldwide export trade, and the extensive diffusion of science to the middle and working classes laid the foundation for the increasing expansiveness Humboldtian research and the fruitful connection between science and government. The social matrix and internal mechanisms of this tidal research demonstrates that Humboldtian initiatives relied on a broad base of support and activity. This included significant contributions from Missionary Societies, the British Association, and especially the British Admiralty, from the Preventive Coast Guard to the Duke of Wellington, then Foreign Secretary. I also stress the essential contribution of the working-classes, a group previous historiography often described as mere data collectors. I uncover their roles in not only gathering data, but in initiating research topics, building self- registering instruments, reducing observational data, and advancing mathematical methods of analysis. Whewell's twenty-year research project helped him formulate what it was to do science and placed him at the forefront of the emerging profession of science in the early Victorian era. His approach to tidology was culled from a study of its history and philosophy and followed two major lines of research. The first entailed finding the phenomenological laws of the tides through long-term observations. His second approach entailed short-term but simultaneous observations along the entire coast of Great Britain, and eventually Europe and America

  8. The Solar Wind - Magnetosphere Energy Coupling Function and Open Magnetic Flux Estimation: Two Science Aspects of the SMILE Mission

    Science.gov (United States)

    Wang, C.; Dai, L.; Sun, T.; Han, J.

    2015-12-01

    The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a novel self-standing mission to observe solar wind - magnetosphere coupling via simultaneous in situ solar wind /magnetosheath plasma and magnetic field measurements, X-ray images of the magnetosphere, and UV images of global auroral distribution defining system - level consequences. The SMILE mission is jointly supported by ESA and CSA, and the launch date is expected to be in 2021. SMILE will address several key outstanding questions concerning how the solar wind interacts with the magnetospheres on a global level. Quantitatively estimating the energy input from the solar wind into the magnetosphere on a global scale is still an observational challenge. Using global MHD simulations, we derive a new solar wind - magnetosphere energy coupling function. The X-ray images of the magnetosphere from the SMILE mission will help estimate the energy transfer from the solar wind into the magnetosphere. A second aspect SMILE can address is the open magnetic flux, which is closely related to magnetic reconnections in the dayside magnetopause and magnetotail. In a similar way, we find that the open magnetic flux can be estimated through a combined parameter f, which is a function of the solar wind velocity, number density, the southern interplanetary magnetic field strength, and the ionospheric Pederson conductance. The UV auroral images from SMILE will be used to determine the open magnetic flux, which may serve as a key space weather forecast element in the future.

  9. Multi-Scale Science Framework for Attributing and Tracking Greenhouse Gas Fluxes at LANL's Four Corners New Mexico Test Bed

    Science.gov (United States)

    Costigan, K. R.; Dubey, M. K.; Chylek, P.; Love, S. P.; Henderson, B. G.; Flowers, B. A.; Reisner, J. M.; Rahn, T.; Quick, C. R.

    2010-12-01

    Agreements to limit greenhouse gas emissions require scientifically valid methods for monitoring and validating anthropogenic emissions. However, the task of monitoring CO2 emissions is difficult because relatively small increases need to be detected against CO2’s variable and large background concentrations. To ensure fair compliance, remotely sensed measurements and an understanding of the atmospheric transport of CO2 from the sources are required. We hypothesize that CO2 from various natural and anthropogenic sources can be distinguished and tracked by monitoring co-emitted gases (e.g. NO2, SO2, and CO) and isotopomers (e.g.13CO2). The ratio of a co-emitted species to CO2 depends on fuel composition and combustion process and thus varies by energy sector. These ratios provide an independent method to quantify CO2 emissions. Their low backgrounds, their large perturbations from energy activities, and our ability to measure them precisely make them sensitive probes to attribute sources, especially when emission ratios of multiple species are used concurrently. This strategy of observing emission ratios of co-emitted species to derive regional and source-specific baselines and CO2 fluxes is being tested in the Four Corners region of northwestern New Mexico. The semi-arid ecology in the region has a weak natural carbon cycle, facilitating our goal of dissection of anthropogenic sector-specific sources. The net Four Corners and San Juan power plant emissions are the largest point source of CO2 and NOx in North America. The Four Corners plant produces much more NOx than the San Juan power plant, while their energy and CO2 outputs, and coal used, are similar. This difference offers us a unique opportunity to test discrimination methods. While their CO2 signals remain elusive for current satellites, their NO2 plumes have recently been resolved from space. The region also experiences dispersed CO2 urban emissions as well as emissions and leaks from thousands of oil

  10. KoFlux: Korean Regional Flux Network in AsiaFlux

    Science.gov (United States)

    Kim, J.

    2002-12-01

    AsiaFlux, the Asian arm of FLUXNET, held the Second International Workshop on Advanced Flux Network and Flux Evaluation in Jeju Island, Korea on 9-11 January 2002. In order to facilitate comprehensive Asia-wide studies of ecosystem fluxes, the meeting launched KoFlux, a new Korean regional network of long-term micrometeorological flux sites. For a successful assessment of carbon exchange between terrestrial ecosystems and the atmosphere, an accurate measurement of surface fluxes of energy and water is one of the prerequisites. During the 7th Global Energy and Water Cycle Experiment (GEWEX) Asian Monsoon Experiment (GAME) held in Nagoya, Japan on 1-2 October 2001, the Implementation Committee of the Coordinated Enhanced Observing Period (CEOP) was established. One of the immediate tasks of CEOP was and is to identify the reference sites to monitor energy and water fluxes over the Asian continent. Subsequently, to advance the regional and global network of these reference sites in the context of both FLUXNET and CEOP, the Korean flux community has re-organized the available resources to establish a new regional network, KoFlux. We have built up domestic network sites (equipped with wind profiler and radiosonde measurements) over deciduous and coniferous forests, urban and rural rice paddies and coastal farmland. As an outreach through collaborations with research groups in Japan, China and Thailand, we also proposed international flux sites at ecologically and climatologically important locations such as a prairie on the Tibetan plateau, tropical forest with mixed and rapid land use change in northern Thailand. Several sites in KoFlux already begun to accumulate interesting data and some highlights are presented at the meeting. The sciences generated by flux networks in other continents have proven the worthiness of a global array of micrometeorological flux towers. It is our intent that the launch of KoFlux would encourage other scientists to initiate and

  11. [The flux of historiography].

    Science.gov (United States)

    Mazzolini, R G

    2001-01-01

    The author places Grmek's editorial within the flux of the historiographical debate which, since the middle of the 1970s, has concentrated on two major crises due to the end of social science-oriented 'scientific history' and to the 'linguistic turn'. He also argues that Grmek's historiographical work of the 1980s and 1990s was to some extent an alternative to certain observed changes in historical fashion and has achieved greater intelligibility because of its commitment to a rational vision of science and historiography.

  12. Critical flux determination by flux-stepping

    DEFF Research Database (Denmark)

    Beier, Søren; Jonsson, Gunnar Eigil

    2010-01-01

    In membrane filtration related scientific literature, often step-by-step determined critical fluxes are reported. Using a dynamic microfiltration device, it is shown that critical fluxes determined from two different flux-stepping methods are dependent upon operational parameters such as step......, such values are more or less useless in itself as critical flux predictors, and constant flux verification experiments have to be conducted to check if the determined critical fluxes call predict sustainable flux regimes. However, it is shown that using the step-by-step predicted critical fluxes as start...

  13. science

    International Development Research Centre (IDRC) Digital Library (Canada)

    David Spurgeon

    green revolution". — seemed to confirm the value of science and technology to international development. Yet studies showed that, at that time, only about two percent of ... gap in science and technology between the Third World and the industrial- ..... Finance; Treasury Board; Industry, Trade and Commerce; Agriculture;.

  14. Atmospheric Renewable Energy Research, Volume 5 (Solar Radiation Flux Model)

    Science.gov (United States)

    2017-09-01

    ARL-TR-8155 ● SEP 2017 US Army Research Laboratory Atmospheric Renewable Energy Research, Volume 5 (Solar Radiation Flux Model... Energy Research, Volume 5 (Solar Radiation Flux Model) by Clayton Walker and Gail Vaucher Computational and Information Sciences Directorate, ARL...2017 June 28 4. TITLE AND SUBTITLE Atmospheric Renewable Energy Research, Volume 5 (Solar Radiation Flux Model) 5a. CONTRACT NUMBER ROTC Internship

  15. Ionic fluxes in erythrocyte membranes of sickle cell anaemia ...

    African Journals Online (AJOL)

    Ionic fluxes in erythrocyte membranes of sickle cell anaemia subjects at different tonicities. ... Journal of African Association of Physiological Sciences ... The aim of this study was to investigate ionic fluxes in membrane of erythrocytes at different tonicities with a view to highlighting any selective ionic-fluxing potential of ...

  16. Physicochemical Flux and Phytoplankton diversity in Shagari ...

    African Journals Online (AJOL)

    USER

    2007-03-20

    Mar 20, 2007 ... Physicochemical Flux and Phytoplankton diversity in Shagari Reservoir,Sokoto, Nigeria. *1I.M. Magami, 1T. Adamu and 2A.A. Aliero. 1Zoology Unit, Department of Biological Sciences, Usmanu Danfodiyo University, Sokoto, Nigeria. 2Botany Unit, Department of Biological Sciences, Usmanu Danfodiyo ...

  17. Radon flux measurement methodologies

    International Nuclear Information System (INIS)

    Nielson, K.K.; Rogers, V.C.

    1984-01-01

    Five methods for measuring radon fluxes are evaluated: the accumulator can, a small charcoal sampler, a large-area charcoal sampler, the ''Big Louie'' charcoal sampler, and the charcoal tent sampler. An experimental comparison of the five flux measurement techniques was also conducted. Excellent agreement was obtained between the measured radon fluxes and fluxes predicted from radium and emanation measurements

  18. Clustering of Emerging Flux

    Science.gov (United States)

    Ruzmaikin, A.

    1997-01-01

    Observations show that newly emerging flux tends to appear on the Solar surface at sites where there is flux already. This results in clustering of solar activity. Standard dynamo theories do not predict this effect.

  19. An undulator based high flux and high resolution beamline for atomic, molecular and optical science (AMOS) research at INDUS-2 synchrotron radiation source (SRS)

    International Nuclear Information System (INIS)

    Das, Asim Kumar; Rajasekhar, B.N.; Sahoo, N.K.

    2014-08-01

    A dedicated UV-VUV and soft X-ray beamline to provide several new research opportunities in Photon induced processes in the energy range of 6-250 eV for Atomic Molecular and Optical Science (AMOS) research, a domain still less explored both at national as well international level, has been proposed by Atomic and Molecular Physics Division, BARC. This beamline will use a planar permanent magnet (PPM) undulator based on Indus-2 Synchrotron Radiation Source (SRS), a 2.5 GeV third generation electron storage ring at RRCAT, Indore, India and is expected to offer a variety of opportunities for more advanced and sustained investigations for AMOS research. A plane mirror and a toroidal mirror are used as the pre-focusing optics of the AMOS beamline. A varied line spacing plane grating monochromator (VLSPGM) in a converging beam, constant included angle mode containing one toroidal focusing mirror and four interchangeable gratings is to be used to cover the energy range of 6 to 250 eV and obtain resolving powers ∼10 4 and intensity ∼10 12 ph/s at the sample position. A toroidal mirror is used to focus the diverging monochromatic light from the monochromator at a distance of 150 cm with a 1:1 magnification. As the first step towards the beamline optics design, the evaluation of the PPM undulator radiation characteristics relevant to beamline design has been performed using the Indus-2 SRS parameters in the long straight section of the ring, PPM undulator parameters, and the empirical expressions available in literature. The software resources such as XOPS, ESRF, France and SPECTRA, Photon factory, Japan have been used for detailed modelling and verification of the empirical computations. Beamline layout preparation, optimization, imaging performance evaluation, and resolving power calculations for ideal beamline optics are carried out using SHADOWVUI, an extension of XOPS software resource. A new mounting of the optical components in the monochromator has been proposed

  20. Compact neutron flux monitor

    International Nuclear Information System (INIS)

    Madhavi, V.; Phatak, P.R.; Bahadur, C.; Bayala, A.K.; Jakati, R.K.; Sathian, V.

    2003-01-01

    Full text: A compact size neutron flux monitor has been developed incorporating standard boards developed for smart radiation monitors. The sensitivity of the monitors is 0.4cps/nV. It has been tested up to 2075 nV flux with standard neutron sources. It shows convincing results even in high flux areas like 6m away from the accelerator in RMC (Parel) for 106/107 nV. These monitors have a focal and remote display, alarm function with potential free contacts for centralized control and additional provision of connectivity via RS485/Ethernet. This paper describes the construction, working and results of the above flux monitor

  1. Video Meteor Fluxes

    Science.gov (United States)

    Campbell-Brown, M. D.; Braid, D.

    2011-01-01

    The flux of meteoroids, or number of meteoroids per unit area per unit time, is critical for calibrating models of meteoroid stream formation and for estimating the hazard to spacecraft from shower and sporadic meteors. Although observations of meteors in the millimetre to centimetre size range are common, flux measurements (particularly for sporadic meteors, which make up the majority of meteoroid flux) are less so. It is necessary to know the collecting area and collection time for a given set of observations, and to correct for observing biases and the sensitivity of the system. Previous measurements of sporadic fluxes are summarized in Figure 1; the values are given as a total number of meteoroids striking the earth in one year to a given limiting mass. The Gr n et al. (1985) flux model is included in the figure for reference. Fluxes for sporadic meteoroids impacting the Earth have been calculated for objects in the centimeter size range using Super-Schmidt observations (Hawkins & Upton, 1958); this study used about 300 meteors, and used only the physical area of overlap of the cameras at 90 km to calculate the flux, corrected for angular speed of meteors, since a large angular speed reduces the maximum brightness of the meteor on the film, and radiant elevation, which takes into account the geometric reduction in flux when the meteors are not perpendicular to the horizontal. They bring up corrections for both partial trails (which tends to increase the collecting area) and incomplete overlap at heights other than 90 km (which tends to decrease it) as effects that will affect the flux, but estimated that the two effects cancelled one another. Halliday et al. (1984) calculated the flux of meteorite-dropping fireballs with fragment masses greater than 50 g, over the physical area of sky accessible to the MORP fireball cameras, counting only observations in clear weather. In the micron size range, LDEF measurements of small craters on spacecraft have been used to

  2. Solar Magnetic Flux Ropes

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The most probable initial magnetic configuration of a CME is a flux rope consisting of twisted field lines which fill the whole volume of a dark coronal cavity. The flux ropes can be in stable equilibrium in the coronal magnetic field for weeks and even months, but suddenly they lose their stability and erupt with ...

  3. Directed flux motor

    Science.gov (United States)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2011-01-01

    A directed flux motor described utilizes the directed magnetic flux of at least one magnet through ferrous material to drive different planetary gear sets to achieve capabilities in six actuated shafts that are grouped three to a side of the motor. The flux motor also utilizes an interwoven magnet configuration which reduces the overall size of the motor. The motor allows for simple changes to modify the torque to speed ratio of the gearing contained within the motor as well as simple configurations for any number of output shafts up to six. The changes allow for improved manufacturability and reliability within the design.

  4. Planck intermediate results - LII. Planet flux densities

    DEFF Research Database (Denmark)

    Akrami, Y.; Ashdown, M.; Aumont, J.

    2017-01-01

    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...... 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-wavelength range to cross-calibrate against Planck and improve models of radiative transport used in planetary science....

  5. Aeronet Solar Flux

    Data.gov (United States)

    National Aeronautics and Space Administration — SolRad-Net (Solar Radiation Network) is an established network of ground-based sensors providing high-frequency solar flux measurements in quasi-realtime to the...

  6. Flux in Tallinn

    Index Scriptorium Estoniae

    2004-01-01

    Rahvusvahelise elektroonilise kunsti sümpoosioni ISEA2004 klubiõhtu "Flux in Tallinn" klubis Bon Bon. Eestit esindasid Ropotator, Ars Intel Inc., Urmas Puhkan, Joel Tammik, Taavi Tulev (pseud. Wochtzchee). Klubiõhtu koordinaator Andres Lõo

  7. Determining Reactor Neutrino Flux

    OpenAIRE

    Cao, Jun

    2011-01-01

    Flux is an important source of uncertainties for a reactor neutrino experiment. It is determined from thermal power measurements, reactor core simulation, and knowledge of neutrino spectra of fuel isotopes. Past reactor neutrino experiments have determined the flux to (2-3)% precision. Precision measurements of mixing angle $\\theta_{13}$ by reactor neutrino experiments in the coming years will use near-far detector configurations. Most uncertainties from reactor will be canceled out. Understa...

  8. Theoretical magnetic flux emergence

    OpenAIRE

    MacTaggart, David

    2011-01-01

    Magnetic flux emergence is the subject of how magnetic fields from the solar interior can rise and expand into the atmosphere to produce active regions. It is the link that joins dynamics in the convection zone with dynamics in the atmosphere. In this thesis, we study many aspects of magnetic flux emergence through mathematical modelling and computer simulations. Our primary aim is to understand the key physical processes that lie behind emergence. The first chapter intro...

  9. Flux Emergence (Theory)

    Science.gov (United States)

    Cheung, Mark C. M.; Isobe, Hiroaki

    2014-07-01

    Magnetic flux emergence from the solar convection zone into the overlying atmosphere is the driver of a diverse range of phenomena associated with solar activity. In this article, we introduce theoretical concepts central to the study of flux emergence and discuss how the inclusion of different physical effects (e.g., magnetic buoyancy, magnetoconvection, reconnection, magnetic twist, interaction with ambient field) in models impact the evolution of the emerging field and plasma.

  10. Neutron flux monitoring device

    International Nuclear Information System (INIS)

    Shimazu, Yoichiro.

    1995-01-01

    In a neutron flux monitoring device, there are disposed a neutron flux measuring means for outputting signals in accordance with the intensity of neutron fluxes, a calculation means for calculating a self power density spectrum at a frequency band suitable to an object to be measured based on the output of the neutron flux measuring means, an alarm set value generation means for outputting an alarm set value as a comparative reference, and an alarm judging means for comparing the alarm set value with the outputted value of the calculation means to judge requirement of generating an alarm and generate an alarm in accordance with the result of the judgement. Namely, the time-series of neutron flux signals is put to fourier transformation for a predetermined period of time by the calculation means, and from each of square sums for real number component and imaginary number component for each of the frequencies, a self power density spectrum in the frequency band suitable to the object to be measured is calculated. Then, when the set reference value is exceeded, an alarm is generated. This can reliably prevent generation of erroneous alarm due to neutron flux noises and can accurately generate an alarm at an appropriate time. (N.H.)

  11. Neutron flux monitor

    International Nuclear Information System (INIS)

    Oda, Naotaka.

    1993-01-01

    The device of the present invention greatly saves an analog processing section such as an analog filter and an analog processing circuit. That is, the device of the present invention comprises (1) a neutron flux detection means for detecting neutron fluxed in the reactor, (2) a digital filter means for dividing signals corresponding to the detected neutron fluxes into predetermined frequency band regions, (3) a calculation processing means for applying a calculation processing corresponding to the frequency band regions to the neutron flux detection signals divided by the digital filter means. With such a constitution, since the neutron detection signals are processed by the digital filter means, the accuracy is improved and the change for the property of the filter is facilitated. Further, when a neutron flux level is obtained, a calculation processing corresponding to the frequency band region can be conducted without the analog processing circuit. Accordingly, maintenance and accuracy are improved by greatly decreasing the number of parts. Further, since problems inherent to the analog circuit are solved, neutron fluxes are monitored at high reliability. (I.S.)

  12. The Open Flux Problem

    International Nuclear Information System (INIS)

    Linker, J. A.; Caplan, R. M.; Downs, C.; Riley, P.; Mikic, Z.; Lionello, R.; Henney, C. J.; Arge, C. N.; Liu, Y.; Derosa, M. L.; Yeates, A.; Owens, M. J.

    2017-01-01

    The heliospheric magnetic field is of pivotal importance in solar and space physics. The field is rooted in the Sun’s photosphere, where it has been observed for many years. Global maps of the solar magnetic field based on full-disk magnetograms are commonly used as boundary conditions for coronal and solar wind models. Two primary observational constraints on the models are (1) the open field regions in the model should approximately correspond to coronal holes (CHs) observed in emission and (2) the magnitude of the open magnetic flux in the model should match that inferred from in situ spacecraft measurements. In this study, we calculate both magnetohydrodynamic and potential field source surface solutions using 14 different magnetic maps produced from five different types of observatory magnetograms, for the time period surrounding 2010 July. We have found that for all of the model/map combinations, models that have CH areas close to observations underestimate the interplanetary magnetic flux, or, conversely, for models to match the interplanetary flux, the modeled open field regions are larger than CHs observed in EUV emission. In an alternative approach, we estimate the open magnetic flux entirely from solar observations by combining automatically detected CHs for Carrington rotation 2098 with observatory synoptic magnetic maps. This approach also underestimates the interplanetary magnetic flux. Our results imply that either typical observatory maps underestimate the Sun’s magnetic flux, or a significant portion of the open magnetic flux is not rooted in regions that are obviously dark in EUV and X-ray emission.

  13. Soluble organic nutrient fluxes

    Science.gov (United States)

    Robert G. Qualls; Bruce L. Haines; Wayne Swank

    2014-01-01

    Our objectives in this study were (i) compare fluxes of the dissolved organic nutrients dissolved organic carbon (DOC), DON, and dissolved organic phosphorus (DOP) in a clearcut area and an adjacent mature reference area. (ii) determine whether concentrations of dissolved organic nutrients or inorganic nutrients were greater in clearcut areas than in reference areas,...

  14. Radiation flux measuring device

    International Nuclear Information System (INIS)

    Corte, E.; Maitra, P.

    1977-01-01

    A radiation flux measuring device is described which employs a differential pair of transistors, the output of which is maintained constant, connected to a radiation detector. Means connected to the differential pair produce a signal representing the log of the a-c component of the radiation detector, thereby providing a signal representing the true root mean square logarithmic output. 3 claims, 2 figures

  15. Muon and neutrino fluxes

    Science.gov (United States)

    Edwards, P. G.; Protheroe, R. J.

    1985-01-01

    The result of a new calculation of the atmospheric muon and neutrino fluxes and the energy spectrum of muon-neutrinos produced in individual extensive air showers (EAS) initiated by proton and gamma-ray primaries is reported. Also explained is the possibility of detecting atmospheric nu sub mu's due to gamma-rays from these sources.

  16. Flux scaling: Ultimate regime

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Flux scaling: Ultimate regime. With the Nusselt number and the mixing length scales, we get the Nusselt number and Reynolds number (w'd/ν) scalings: and or. and. scaling expected to occur at extremely high Ra Rayleigh-Benard convection. Get the ultimate regime ...

  17. ULY JUP COSPIN HIGH FLUX TELESCOPE HIGH RES. ION FLUX

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains ion flux data recorded by the COSPIN High Flux Telescope (HFT) during the Ulysses Jupiter encounter 1992-Jan-25 to 1992-Feb-18.

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

    Science.gov (United States)

    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.

  19. Atmospheric lepton fluxes

    Directory of Open Access Journals (Sweden)

    Gaisser Thomas K.

    2015-01-01

    Full Text Available This review of atmospheric muons and neutrinos emphasizes the high energy range relevant for backgrounds to high-energy neutrinos of astrophysical origin. After a brief historical introduction, the main distinguishing features of atmospheric νμ and νe are discussed, along with the implications of the muon charge ratio for the νµ / ν̅µ ratio. Methods to account for effects of the knee in the primary cosmic-ray spectrum and the energy-dependence of hadronic interactions on the neutrino fluxes are discussed and illustrated in the context of recent results from IceCube. A simple numerical/analytic method is proposed for systematic investigation of uncertainties in neutrino fluxes arising from uncertainties in the primary cosmic-ray spectrum/composition and hadronic interactions.

  20. NEUTRON FLUX INTENSITY DETECTION

    Science.gov (United States)

    Russell, J.T.

    1964-04-21

    A method of measuring the instantaneous intensity of neutron flux in the core of a nuclear reactor is described. A target gas capable of being transmuted by neutron bombardment to a product having a resonance absorption line nt a particular microwave frequency is passed through the core of the reactor. Frequency-modulated microwave energy is passed through the target gas and the attenuation of the energy due to the formation of the transmuted product is measured. (AEC)

  1. Physics of magnetic flux ropes

    Science.gov (United States)

    Russell, C. T.; Priest, E. R.; Lee, L. C.

    The present work encompasses papers on the structure, waves, and instabilities of magnetic flux ropes (MFRs), photospheric flux tubes (PFTs), the structure and heating of coronal loops, solar prominences, coronal mass ejections and magnetic clouds, flux ropes in planetary ionospheres, the magnetopause, magnetospheric field-aligned currents and flux tubes, and the magnetotail. Attention is given to the equilibrium of MFRs, resistive instability, magnetic reconnection and turbulence in current sheets, dynamical effects and energy transport in intense flux tubes, waves in solar PFTs, twisted flux ropes in the solar corona, an electrodynamical model of solar flares, filament cooling and condensation in a sheared magnetic field, the magnetopause, the generation of twisted MFRs during magnetic reconnection, ionospheric flux ropes above the South Pole, substorms and MFR structures, evidence for flux ropes in the earth magnetotail, and MFRs in 3D MHD simulations.

  2. Scale aggregation - comparison of flux estimates from NOPEX

    DEFF Research Database (Denmark)

    Gottschalk, L.; Batchvarova, E.; Gryning, Sven-Erik

    1999-01-01

    The NOPEX two concentrated field efforts (CFEs) (June 1994 and April-July 1995) provide high quality data sets for the Boreal environment. The analysis of these data with traditional meteorological and hydrological approaches allow estimations of fluxes of latent and sensible heat, but these flux...... use weighted mast estimates. For the latent heat flux good agreement was found between the regional latent heat Bur derived from airplane measurements, land use weighted mast estimates, and the two mesoscale numerical models. (C) 1999 Elsevier Science B.V. All rights reserved....

  3. Reactor flux calculations

    Energy Technology Data Exchange (ETDEWEB)

    Lhuillier, D. [Commissariat à l' Énergie Atomique et aux Énergies Alternatives, Centre de Saclay, IRFU/SPhN, 91191 Gif-sur-Yvette (France)

    2013-02-15

    The status of the prediction of reactor anti-neutrino spectra is presented. The most accurate method is still the conversion of total β spectra of fissionning isotopes as measured at research reactors. Recent re-evaluations of the conversion process led to an increased predicted flux by few percent and were at the origin of the so-called reactor anomaly. The up to date predictions are presented with their main sources of error. Perspectives are given on the complementary ab-initio predictions and upcoming experimental cross-checks of the predicted spectrum shape.

  4. Australian methane fluxes

    International Nuclear Information System (INIS)

    Williams, D.J.

    1990-01-01

    Estimates are provided for the amount of methane emitted annually into the atmosphere in Australia for a variety of sources. The sources considered are coal mining, landfill, motor vehicles, natural gas suply system, rice paddies, bushfires, termites, wetland and animals. This assessment indicates that the major sources of methane are natural or agricultural in nature and therefore offer little scope for reduction. Nevertheless the remainder are not trival and reduction of these fluxes could play a significant part in any Australian action on the greenhouse problem. 19 refs., 7 tabs., 1 fig

  5. Permanent magnet flux-biased magnetic actuator with flux feedback

    Science.gov (United States)

    Groom, Nelson J. (Inventor)

    1991-01-01

    The invention is a permanent magnet flux-biased magnetic actuator with flux feedback for adjustably suspending an element on a single axis. The magnetic actuator includes a pair of opposing electromagnets and provides bi-directional forces along the single axis to the suspended element. Permanent magnets in flux feedback loops from the opposing electromagnets establish a reference permanent magnet flux-bias to linearize the force characteristics of the electromagnets to extend the linear range of the actuator without the need for continuous bias currents in the electromagnets.

  6. Sadhana | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    heat pump system with economizer in HT cycle · Alok Manas Dubey Suresh Kumar Ghanshyam Das ... pp 467-485 Mechanical Sciences. Laminar flow heat transfer studies in a twisted square duct for constant wall heat flux boundary condition.

  7. Reactor neutron flux measuring device

    International Nuclear Information System (INIS)

    Okutani, Yasushi; Hayakawa, Toshifumi.

    1994-01-01

    The present invention concerns a device for displaying an approximate neutron flux distribution to recognize the neutron flux distribution of the whole reactor in a short period of time. The device of the present invention displays, the results of measurement for neutron fluxes collected by a data collecting section on every results of the measurements at measuring points situating at horizontally identical positions of the reactor core. In addition, every results of the measurements at the measuring points situating at the identical height in the reactor core are accumulated, and the results of the integration are graphically displayed. With such procedures, the neutron flux distribution in the entire reactor is approximately displayed. Existent devices could not recognize the neutron flux distribution of the entire reactor at a glance and it took much time for the recognition. The device of the present invention can recognize the neutron flux distribution of the entire reactor in a short period of time. (I.S.)

  8. Flux compactifications and generalized geometries

    International Nuclear Information System (INIS)

    Grana, Mariana

    2006-01-01

    Following the lectures given at CERN Winter School 2006, we present a pedagogical overview of flux compactifications and generalized geometries, concentrating on closed string fluxes in type II theories. We start by reviewing the supersymmetric flux configurations with maximally symmetric four-dimensional spaces. We then discuss the no-go theorems (and their evasion) for compactifications with fluxes. We analyse the resulting four-dimensional effective theories for Calabi-Yau and Calabi-Yau orientifold compactifications, concentrating on the flux-induced superpotentials. We discuss the generic mechanism of moduli stabilization and illustrate with two examples: the conifold in IIB and a T 6 /(Z 3 x Z 3 ) torus in IIA. We finish by studying the effective action and flux vacua for generalized geometries in the context of generalized complex geometry

  9. California's Future Carbon Flux

    Science.gov (United States)

    Xu, L.; Pyles, R. D.; Paw U, K.; Gertz, M.

    2008-12-01

    The diversity of the climate and vegetation systems in the state of California provides a unique opportunity to study carton dioxide exchange between the terrestrial biosphere and the atmosphere. In order to accurately calculate the carbon flux, this study couples the sophisticated analytical surface layer model ACASA (Advance Canopy-Atmosphere-Soil Algorithm, developed in the University of California, Davis) with the newest version of mesoscale model WRF (the Weather Research & Forecasting Model, developed by NCAR and several other agencies). As a multilayer, steady state model, ACASA incorporates higher-order representations of vertical temperature variations, CO2 concentration, radiation, wind speed, turbulent statistics, and plant physiology. The WRF-ACASA coupling is designed to identify how multiple environmental factors, in particularly climate variability, population density, and vegetation distribution, impact on future carbon cycle prediction across a wide geographical range such as in California.

  10. Neutron fluxes in test reactors

    Energy Technology Data Exchange (ETDEWEB)

    Youinou, Gilles Jean-Michel [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-01-01

    Communicate the fact that high-power water-cooled test reactors such as the Advanced Test Reactor (ATR), the High Flux Isotope Reactor (HFIR) or the Jules Horowitz Reactor (JHR) cannot provide fast flux levels as high as sodium-cooled fast test reactors. The memo first presents some basics physics considerations about neutron fluxes in test reactors and then uses ATR, HFIR and JHR as an illustration of the performance of modern high-power water-cooled test reactors.

  11. Data Acquisition and Flux Calculations

    DEFF Research Database (Denmark)

    Rebmann, C.; Kolle, O; Heinesch, B

    2012-01-01

    In this chapter, the basic theory and the procedures used to obtain turbulent fluxes of energy, mass, and momentum with the eddy covariance technique will be detailed. This includes a description of data acquisition, pretreatment of high-frequency data and flux calculation.......In this chapter, the basic theory and the procedures used to obtain turbulent fluxes of energy, mass, and momentum with the eddy covariance technique will be detailed. This includes a description of data acquisition, pretreatment of high-frequency data and flux calculation....

  12. Heat Flux Instrumentation Laboratory (HFIL)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: The Heat Flux Instrumentation Laboratory is used to develop advanced, flexible, thin film gauge instrumentation for the Air Force Research Laboratory....

  13. Critical heat flux in flow boiling in microchannels

    CERN Document Server

    Saha, Sujoy Kumar

    2015-01-01

    This Brief concerns the important problem of critical heat flux in flow boiling in microchannels. A companion edition in the SpringerBrief Subseries on Thermal Engineering and Applied Science to “Heat Transfer and Pressure Drop in Flow Boiling in Microchannels,” by the same author team, this volume is idea for professionals, researchers, and graduate students concerned with electronic cooling.

  14. Flux-Vortex Pinning and Neutron Star Evolution

    Indian Academy of Sciences (India)

    M. Ali Alpar

    Flux-Vortex Pinning and Neutron Star Evolution. M. ALI ALPAR. Faculty of Engineering and Natural Sciences, Sabancı University, 34956, Istanbul, Turkey. E-mail: alpar@sabanciuniv.edu. MS received 22 May 2017; accepted 24 July 2017; published online 12 September 2017. Abstract. G. Srinivasan et al. (1990) proposed ...

  15. Carbon dioxide, water vapour and energy fluxes over a semi ...

    Indian Academy of Sciences (India)

    42

    1Department of Environmental Science, Tezpur Central University, Tezpur 784028, Assam,. India. 2Prince Of Wales Institute Of Engineering & Technology, Jorhat, Assam; 3Indian Institute. Of Tropical Meteorology, Pune; 4Savitribai Phule Pune University, Pune, India. Carbon dioxide, water vapour and energy fluxes over a ...

  16. Kubo Resistivity of magnetic flux ropes

    Science.gov (United States)

    Gekelman, Walter; Dehaas, Tim; Pribyl, Pat; Vincena, Stephen; van Compernolle, Bart; Sydora, Rick; Tang, Shawn Wenjie

    2017-10-01

    Magnetic flux ropes are bundles of twisted magnetic fields and their associated current. They are common on the surface of the sun (and presumably all other stars) and are observed to have a large range of sizes and lifetimes. They can become unstable and resulting in coronal mass ejections that can travel to earth and indeed, have been observed by satellites. Two side by side flux ropes are generated in the LAPD device at UCLA. Using a series of novel diagnostics the following key quantities, B, u, Vp, n, Te have been measured at more than 48,000 spatial locations and 7,000 time steps. Every term in Ohm's law is also evaluated across and along the local magnetic field and the plasma resistivity derived and it is shown that Ohms law is non-local. The electron distribution function parallel and antiparallel to the background magnetic field was measured and found to be a drifting Kappa function. The Kubo AC conductivity at the flux rope rotation frequency, a 3X3 tensor, was evaluated using velocity correlations and will be presented. This yields meaningful results for the global resistivity. Frequency spectra and the presence of time domain structures may offer a clue to the enhanced resistivity. Work supported by the Department of Energy and National Science Foundation.

  17. From elementary flux modes to elementary flux vectors: Metabolic pathway analysis with arbitrary linear flux constraints

    Science.gov (United States)

    Klamt, Steffen; Gerstl, Matthias P.; Jungreuthmayer, Christian; Mahadevan, Radhakrishnan; Müller, Stefan

    2017-01-01

    Elementary flux modes (EFMs) emerged as a formal concept to describe metabolic pathways and have become an established tool for constraint-based modeling and metabolic network analysis. EFMs are characteristic (support-minimal) vectors of the flux cone that contains all feasible steady-state flux vectors of a given metabolic network. EFMs account for (homogeneous) linear constraints arising from reaction irreversibilities and the assumption of steady state; however, other (inhomogeneous) linear constraints, such as minimal and maximal reaction rates frequently used by other constraint-based techniques (such as flux balance analysis [FBA]), cannot be directly integrated. These additional constraints further restrict the space of feasible flux vectors and turn the flux cone into a general flux polyhedron in which the concept of EFMs is not directly applicable anymore. For this reason, there has been a conceptual gap between EFM-based (pathway) analysis methods and linear optimization (FBA) techniques, as they operate on different geometric objects. One approach to overcome these limitations was proposed ten years ago and is based on the concept of elementary flux vectors (EFVs). Only recently has the community started to recognize the potential of EFVs for metabolic network analysis. In fact, EFVs exactly represent the conceptual development required to generalize the idea of EFMs from flux cones to flux polyhedra. This work aims to present a concise theoretical and practical introduction to EFVs that is accessible to a broad audience. We highlight the close relationship between EFMs and EFVs and demonstrate that almost all applications of EFMs (in flux cones) are possible for EFVs (in flux polyhedra) as well. In fact, certain properties can only be studied with EFVs. Thus, we conclude that EFVs provide a powerful and unifying framework for constraint-based modeling of metabolic networks. PMID:28406903

  18. Squeezing Flux Out of Fat

    DEFF Research Database (Denmark)

    Gonzalez-Franquesa, Alba; Patti, Mary-Elizabeth

    2018-01-01

    Merging transcriptomics or metabolomics data remains insufficient for metabolic flux estimation. Ramirez et al. integrate a genome-scale metabolic model with extracellular flux data to predict and validate metabolic differences between white and brown adipose tissue. This method allows both metab...

  19. Automated calculation of surface energy fluxes with high-frequency lake buoy data

    Science.gov (United States)

    Woolway, R. Iestyn; Jones, Ian D; Hamilton, David P.; Maberly, Stephen C; Muroaka, Kohji; Read, Jordan S.; Smyth, Robyn L; Winslow, Luke A.

    2015-01-01

    Lake Heat Flux Analyzer is a program used for calculating the surface energy fluxes in lakes according to established literature methodologies. The program was developed in MATLAB for the rapid analysis of high-frequency data from instrumented lake buoys in support of the emerging field of aquatic sensor network science. To calculate the surface energy fluxes, the program requires a number of input variables, such as air and water temperature, relative humidity, wind speed, and short-wave radiation. Available outputs for Lake Heat Flux Analyzer include the surface fluxes of momentum, sensible heat and latent heat and their corresponding transfer coefficients, incoming and outgoing long-wave radiation. Lake Heat Flux Analyzer is open source and can be used to process data from multiple lakes rapidly. It provides a means of calculating the surface fluxes using a consistent method, thereby facilitating global comparisons of high-frequency data from lake buoys.

  20. Data Analysis and Instrument Performance Assessment for Regional Carbon Flux Estimates

    Data.gov (United States)

    National Aeronautics and Space Administration — The initial test and science flights of the Sherpa airborne system for direct greenhouse gas (GHG) flux measurements were completed in September 2016. Here we plan...

  1. Principal Metabolic Flux Mode Analysis.

    Science.gov (United States)

    Bhadra, Sahely; Blomberg, Peter; Castillo, Sandra; Rousu, Juho; Wren, Jonathan

    2018-02-06

    In the analysis of metabolism, two distinct and complementary approaches are frequently used: Principal component analysis (PCA) and stoichiometric flux analysis. PCA is able to capture the main modes of variability in a set of experiments and does not make many prior assumptions about the data, but does not inherently take into account the flux mode structure of metabolism. Stoichiometric flux analysis methods, such as Flux Balance Analysis (FBA) and Elementary Mode Analysis, on the other hand, are able to capture the metabolic flux modes, however, they are primarily designed for the analysis of single samples at a time, and not best suited for exploratory analysis on a large sets of samples. We propose a new methodology for the analysis of metabolism, called Principal Metabolic Flux Mode Analysis (PMFA), which marries the PCA and stoichiometric flux analysis approaches in an elegant regularized optimization framework. In short, the method incorporates a variance maximization objective form PCA coupled with a stoichiometric regularizer, which penalizes projections that are far from any flux modes of the network. For interpretability, we also introduce a sparse variant of PMFA that favours flux modes that contain a small number of reactions. Our experiments demonstrate the versatility and capabilities of our methodology. The proposed method can be applied to genome-scale metabolic network in efficient way as PMFA does not enumerate elementary modes. In addition, the method is more robust on out-of-steady steady-state experimental data than competing flux mode analysis approaches. Matlab software for PMFA and SPMFA and data set used for experiments are available in https://github.com/aalto-ics-kepaco/PMFA. sahely@iitpkd.ac.in, juho.rousu@aalto.fi, Peter.Blomberg@vtt.fi, Sandra.Castillo@vtt.fi. Detailed results are in Supplementary files. Supplementary data are available at https://github.com/aalto-ics-kepaco/PMFA/blob/master/Results.zip.

  2. Interpreting Flux from Broadband Photometry

    Science.gov (United States)

    Brown, Peter J.; Breeveld, Alice; Roming, Peter W. A.; Siegel, Michael

    2016-10-01

    We discuss the transformation of observed photometry into flux for the creation of spectral energy distributions (SED) and the computation of bolometric luminosities. We do this in the context of supernova studies, particularly as observed with the Swift spacecraft, but the concepts and techniques should be applicable to many other types of sources and wavelength regimes. Traditional methods of converting observed magnitudes to flux densities are not very accurate when applied to UV photometry. Common methods for extinction and the integration of pseudo-bolometric fluxes can also lead to inaccurate results. The sources of inaccuracy, though, also apply to other wavelengths. Because of the complicated nature of translating broadband photometry into monochromatic flux densities, comparison between observed photometry and a spectroscopic model is best done by forward modeling the spectrum into the count rates or magnitudes of the observations. We recommend that integrated flux measurements be made using a spectrum or SED which is consistent with the multi-band photometry rather than converting individual photometric measurements to flux densities, linearly interpolating between the points, and integrating. We also highlight some specific areas where the UV flux can be mischaracterized.

  3. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Vinay Kumar Dadhwal. Articles written in Journal of Earth System Science. Volume 122 Issue 5 October 2013 pp 1259-1268. Analysis of carbon dioxide, water vapour and energy fluxes over an Indian teak mixed deciduous forest for winter and summer months using eddy ...

  4. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Kiran Chand Thumaty. Articles written in Journal of Earth System Science. Volume 122 Issue 5 October 2013 pp 1259-1268. Analysis of carbon dioxide, water vapour and energy fluxes over an Indian teak mixed deciduous forest for winter and summer months using eddy ...

  5. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Chandra Shekhar Jha. Articles written in Journal of Earth System Science. Volume 122 Issue 5 October 2013 pp 1259-1268. Analysis of carbon dioxide, water vapour and energy fluxes over an Indian teak mixed deciduous forest for winter and summer months using eddy ...

  6. Fluxes of ammonia in the coastal marine boundary layer

    DEFF Research Database (Denmark)

    Sørensen, L.L.; Hertel, O.; Skjøth, C.A.

    2003-01-01

    Concentrations of ammonia in air and ammonium in surface water were measured from a platform in the Southern North Sea close to the Dutch coast. Fluxes were derived from the measurements applying Monin-Obukhov similarity theory and exchange velocities calculated. The fluxes and air concentrations...... and that the calculated overall ammonia dry deposition may be overestimated by a factor two or more in the coastal region. A more detailed study is needed in order to quantify how this may influence overall deposition to given marine waters. In some cases the deposition may solely be redistributed whereas the total...... deposition is only marginally influenced. (C) 2003 Elsevier Science Ltd. All rights reserved....

  7. Specification of ROP flux shape

    Energy Technology Data Exchange (ETDEWEB)

    Min, Byung Joo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Gray, A. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada)

    1997-06-01

    The CANDU 9 480/SEU core uses 0.9% SEU (Slightly Enriched Uranium) fuel. The use f SEU fuel enables the reactor to increase the radial power form factor from 0.865, which is typical in current natural uranium CANDU reactors, to 0.97 in the nominal CANDU 9 480/SEU core. The difference is a 12% increase in reactor power. An additional 5% increase can be achieved due to a reduced refuelling ripple. The channel power limits were also increased by 3% for a total reactor power increase of 20%. This report describes the calculation of neutron flux distributions in the CANDU 9 480/SEU core under conditions specified by the C and I engineers. The RFSP code was used to calculate of neutron flux shapes for ROP analysis. Detailed flux values at numerous potential detector sites were calculated for each flux shape. (author). 6 tabs., 70 figs., 4 refs.

  8. Notes on neutron flux measurement

    International Nuclear Information System (INIS)

    Alcala Ruiz, F.

    1984-01-01

    The main purpose of this work is to get an useful guide to carry out topical neutron flux measurements. Although the foil activation technique is used in the majority of the cases, other techniques, such as those based on fission chambers and self-powered neutron detectors, are also shown. Special interest is given to the description and application of corrections on the measurement of relative and absolute induced activities by several types of detectors (scintillators, G-M and gas proportional counters). The thermal arid epithermal neutron fluxes, as determined in this work, are conventional or effective (West cots fluxes), which are extensively used by the reactor experimentalists; however, we also give some expressions where they are related to the integrated neutron fluxes, which are used in neutron calculations. (Author) 16 refs

  9. Conical electromagnetic radiation flux concentrator

    Science.gov (United States)

    Miller, E. R.

    1972-01-01

    Concentrator provides method of concentrating a beam of electromagnetic radiation into a smaller beam, presenting a higher flux density. Smaller beam may be made larger by sending radiation through the device in the reverse direction.

  10. High Flux Isotope Reactor (HFIR)

    Data.gov (United States)

    Federal Laboratory Consortium — The HFIR at Oak Ridge National Laboratory is a light-water cooled and moderated reactor that is the United States’ highest flux reactor-based neutron source. HFIR...

  11. Radiation belt electron flux forecasts: Driving VERB using NARMAX GSO flux forecasts

    Science.gov (United States)

    Walker, S. N.; Balikhin, M. A.; Boynton, R.; Drozdov, A.; Pakhotin, I.; Shprits, Y. Y.

    2016-12-01

    Physics based models, such as VERB, are capable of achieving excellent past-cast and now-cast models of the dynamics of electron fluxes throughout the radiation belt region. Their ability to forecast, however, is strongly dependant upon the accurate forecast of their driving parameters. In contrast, data based models, generated using Systems Science methodologies such as NARMAX, have been shown to achieve highly accurate forecasts over limited spatial domains such as GSO. This paper outlines the use of NARMAX forecasts to drive VERB. Example past-casts are discussed and compared to observations from the Van Allen Probe MagEIS instrument.

  12. Flux tubes at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Cea, Paolo [INFN, Sezione di Bari,Via G. Amendola 173, I-70126 Bari (Italy); Dipartimento di Fisica dell’Università di Bari,Via G. Amendola 173, I-70126 Bari (Italy); Cosmai, Leonardo [INFN, Sezione di Bari,Via G. Amendola 173, I-70126 Bari (Italy); Cuteri, Francesca; Papa, Alessandro [Dipartimento di Fisica, Università della Calabria & INFN-Cosenza,Ponte Bucci, cubo 31C, I-87036 Rende (Cosenza) (Italy)

    2016-06-07

    The chromoelectric field generated by a static quark-antiquark pair, with its peculiar tube-like shape, can be nicely described, at zero temperature, within the dual superconductor scenario for the QCD confining vacuum. In this work we investigate, by lattice Monte Carlo simulations of the SU(3) pure gauge theory, the fate of chromoelectric flux tubes across the deconfinement transition. We find that, if the distance between the static sources is kept fixed at about 0.76 fm ≃1.6/√σ and the temperature is increased towards and above the deconfinement temperature T{sub c}, the amplitude of the field inside the flux tube gets smaller, while the shape of the flux tube does not vary appreciably across deconfinement. This scenario with flux-tube “evaporation” above T{sub c} has no correspondence in ordinary (type-II) superconductivity, where instead the transition to the phase with normal conductivity is characterized by a divergent fattening of flux tubes as the transition temperature is approached from below. We present also some evidence about the existence of flux-tube structures in the magnetic sector of the theory in the deconfined phase.

  13. The Impact of Prior Biosphere Models in the Inversion of Global Terrestrial CO2 Fluxes by Assimilating OCO-2 Retrievals

    Science.gov (United States)

    Philip, Sajeev; Johnson, Matthew S.

    2018-01-01

    Atmospheric mixing ratios of carbon dioxide (CO2) are largely controlled by anthropogenic emissions and biospheric fluxes. The processes controlling terrestrial biosphere-atmosphere carbon exchange are currently not fully understood, resulting in terrestrial biospheric models having significant differences in the quantification of biospheric CO2 fluxes. Atmospheric transport models assimilating measured (in situ or space-borne) CO2 concentrations to estimate "top-down" fluxes, generally use these biospheric CO2 fluxes as a priori information. Most of the flux inversion estimates result in substantially different spatio-temporal posteriori estimates of regional and global biospheric CO2 fluxes. The Orbiting Carbon Observatory 2 (OCO-2) satellite mission dedicated to accurately measure column CO2 (XCO2) allows for an improved understanding of global biospheric CO2 fluxes. OCO-2 provides much-needed CO2 observations in data-limited regions facilitating better global and regional estimates of "top-down" CO2 fluxes through inversion model simulations. The specific objectives of our research are to: 1) conduct GEOS-Chem 4D-Var assimilation of OCO-2 observations, using several state-of-the-science biospheric CO2 flux models as a priori information, to better constrain terrestrial CO2 fluxes, and 2) quantify the impact of different biospheric model prior fluxes on OCO-2-assimilated a posteriori CO2 flux estimates. Here we present our assessment of the importance of these a priori fluxes by conducting Observing System Simulation Experiments (OSSE) using simulated OCO-2 observations with known "true" fluxes.

  14. Science and Science Fiction

    Science.gov (United States)

    Oravetz, David

    2005-01-01

    This article is for teachers looking for new ways to motivate students, increase science comprehension, and understanding without using the old standard expository science textbook. This author suggests reading a science fiction novel in the science classroom as a way to engage students in learning. Using science fiction literature and language…

  15. Parasitic momentum flux in the tokamak core

    Science.gov (United States)

    Stoltzfus-Dueck, T.

    2017-10-01

    Tokamak plasmas rotate spontaneously without applied torque. This intrinsic rotation is important for future low-torque devices such as ITER, since rotation stabilizes certain instabilities. In the mid-radius `gradient region,' which reaches from the sawtooth inversion radius out to the pedestal top, intrinsic rotation profiles may be either flat or hollow, and can transition suddenly between these two states, an unexplained phenomenon referred to as rotation reversal. Theoretical efforts to explain the mid-radius rotation shear have largely focused on quasilinear models, in which the phase relationships of some selected instability result in a nondiffusive momentum flux (``residual stress''). In contrast, the present work demonstrates the existence of a robust, fully nonlinear symmetry-breaking momentum flux that follows from the free-energy flow in phase space and does not depend on any assumed linear eigenmode structure. The physical origin is an often-neglected portion of the radial ExB drift, which is shown to drive a symmetry-breaking outward flux of co-current momentum whenever free energy is transferred from the electrostatic potential to ion parallel flows. The fully nonlinear derivation relies only on conservation properties and symmetry, thus retaining the important contribution of damped modes. The resulting rotation peaking is counter-current and scales as temperature over plasma current. As first demonstrated by Landau, this free-energy transfer (thus also the corresponding residual stress) becomes inactive when frequencies are much higher than the ion transit frequency, which allows sudden transitions between hollow and flat profiles. Simple estimates suggest that this mechanism may be consistent with experimental observations. This work was funded in part by the Max-Planck/Princeton Center for Plasma Physics and in part by the U.S. Dept. of Energy, Office of Science, Contract No. DE-AC02-09CH11466.

  16. Primary Metabolic Pathways and Metabolic Flux Analysis

    DEFF Research Database (Denmark)

    Villadsen, John

    2015-01-01

    his chapter introduces the metabolic flux analysis (MFA) or stoichiometry-based MFA, and describes the quantitative basis for MFA. It discusses the catabolic pathways in which free energy is produced to drive the cell-building anabolic pathways. An overview of these primary pathways provides...... the reader who is primarily trained in the engineering sciences with atleast a preliminary introduction to biochemistry and also shows how carbon is drained off the catabolic pathways to provide precursors for cell mass building and sometimes for important industrial products. The primary pathways...... to be examined in the following are: glycolysis, primarily by the EMP pathway, but other glycolytic pathways is also mentioned; fermentative pathways in which the redox generated in the glycolytic reactions are consumed; reactions in the tricarboxylic acid (TCA) cycle, which produce biomass precursors and redox...

  17. Physics of magnetic flux tubes

    CERN Document Server

    Ryutova, Margarita

    2015-01-01

    This book is the first account of the physics of magnetic flux tubes from their fundamental properties to collective phenomena in an ensembles of flux tubes. The physics of magnetic flux tubes is absolutely vital for understanding fundamental physical processes in the solar atmosphere shaped and governed by magnetic fields. High-resolution and high cadence observations from recent space and  ground-based instruments taken simultaneously at different heights and temperatures not only show the ubiquity of filamentary structure formation but also allow to study how various events are interconnected by system of magnetic flux tubes. The book covers both theory and observations. Theoretical models presented in analytical and phenomenological forms are tailored for practical applications. These are welded with state-of-the-art observations from early decisive ones to the most recent data that open a new phase-space for exploring the Sun and sun-like stars. Concept of magnetic flux tubes is central to various magn...

  18. Flux driven turbulence in tokamaks

    International Nuclear Information System (INIS)

    Garbet, X.; Ghendrih, P.; Ottaviani, M.; Sarazin, Y.; Beyer, P.; Benkadda, S.; Waltz, R.E.

    1999-01-01

    This work deals with tokamak plasma turbulence in the case where fluxes are fixed and profiles are allowed to fluctuate. These systems are intermittent. In particular, radially propagating fronts, are usually observed over a broad range of time and spatial scales. The existence of these fronts provide a way to understand the fast transport events sometimes observed in tokamaks. It is also shown that the confinement scaling law can still be of the gyroBohm type in spite of these large scale transport events. Some departure from the gyroBohm prediction is observed at low flux, i.e. when the gradients are close to the instability threshold. Finally, it is found that the diffusivity is not the same for a turbulence calculated at fixed flux than at fixed temperature gradient, with the same time averaged profile. (author)

  19. Looking for high neutron fluxes

    International Nuclear Information System (INIS)

    Lengeler, Herbert

    1994-01-01

    The neutron is a powerful and versatile probe of both the structure and dynamics of condensed matter. However unlike other techniques such as X-ray, electron or light scattering, its interaction with matter is rather weak. Historically neutron scattering has always been intensity limited and scientists are always looking for more intense sources. These come in two kinds - fission reactors and spallation sources (in which neutrons are released from a target bombardment by beams). Unfortunately the power density of high flux reactors is approaching a technical limit and it will be difficult to achieve a large increase of neutron fluxes above typical present values as represented for example by the high flux reactor at ILL, Grenoble

  20. DISCONNECTING OPEN SOLAR MAGNETIC FLUX

    International Nuclear Information System (INIS)

    DeForest, C. E.; Howard, T. A.; McComas, D. J.

    2012-01-01

    Disconnection of open magnetic flux by reconnection is required to balance the injection of open flux by coronal mass ejections and other eruptive events. Making use of recent advances in heliospheric background subtraction, we have imaged many abrupt disconnection events. These events produce dense plasma clouds whose distinctive shape can now be traced from the corona across the inner solar system via heliospheric imaging. The morphology of each initial event is characteristic of magnetic reconnection across a current sheet, and the newly disconnected flux takes the form of a 'U-'shaped loop that moves outward, accreting coronal and solar wind material. We analyzed one such event on 2008 December 18 as it formed and accelerated at 20 m s –2 to 320 km s –1 , thereafter expanding self-similarly until it exited our field of view 1.2 AU from the Sun. From acceleration and photometric mass estimates we derive the coronal magnetic field strength to be 8 μT, 6 R ☉ above the photosphere, and the entrained flux to be 1.6 × 10 11 Wb (1.6 × 10 19 Mx). We model the feature's propagation by balancing inferred magnetic tension force against accretion drag. This model is consistent with the feature's behavior and accepted solar wind parameters. By counting events over a 36 day window, we estimate a global event rate of 1 day –1 and a global solar minimum unsigned flux disconnection rate of 6 × 10 13 Wb yr –1 (6 × 10 21 Mx yr –1 ) by this mechanism. That rate corresponds to ∼ – 0.2 nT yr –1 change in the radial heliospheric field at 1 AU, indicating that the mechanism is important to the heliospheric flux balance.

  1. Anthropogenic heat flux estimation from space: first results

    Science.gov (United States)

    Chrysoulakis, Nektarios; Heldens, Wieke; Gastellu-Etchegorry, Jean-Philippe; Grimmond, Sue; Feigenwinter, Christian; Lindberg, Fredrik; Del Frate, Fabio; Klostermann, Judith; Mitraka, Zina; Esch, Thomas; Albitar, Ahmad; Gabey, Andrew; Parlow, Eberhard; Olofson, Frans

    2016-04-01

    While Earth Observation (EO) has made significant advances in the study of urban areas, there are several unanswered science and policy questions to which it could contribute. To this aim the recently launched Horizon 2020 project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of EO to retrieve anthropogenic heat flux, as a key component in the urban energy budget. The anthropogenic heat flux is the heat flux resulting from vehicular emissions, space heating and cooling of buildings, industrial processing and the metabolic heat release by people. Optical, thermal and SAR data from existing satellite sensors are used to improve the accuracy of the radiation balance spatial distribution calculation, using also in-situ reflectance measurements of urban materials are for calibration. EO-based methods are developed for estimating turbulent sensible and latent heat fluxes, as well as urban heat storage flux and anthropogenic heat flux spatial patterns at city scale and local scale by employing an energy budget closure approach. Independent methods and models are engaged to evaluate the derived products and statistical analyses provide uncertainty measures as well. Ultimate goal of the URBANFLUXES is to develop a highly automated method for estimating urban energy budget components to use with Copernicus Sentinel data, enabling its integration into applications and operational services. Thus, URBANFLUXES prepares the ground for further innovative exploitation of European space data in scientific activities (i.e. Earth system modelling and climate change studies in cities) and future and emerging applications (i.e. sustainable urban planning) by exploiting the improved data quality, coverage and revisit times of the Copernicus data. The URBANFLUXES products will therefore have the potential to support both sustainable planning strategies to improve the quality of life in cities, as well as Earth system models to

  2. The gradiometer flux qubit without an external flux bias

    International Nuclear Information System (INIS)

    Wu, C E; Liu, Y; Chi, C C

    2006-01-01

    We analyse the potential of the gradiometer flux qubit (GFQ), which should be insensitive to flux noise because of the nature of the gradiometer structure. However, to enjoy the benefit of such a design, we must be careful in choosing the initial condition. In the fluxoid quantization condition the flux integer n, which is set to zero in the usual single-loop flux qubit analysis, plays an important role in the GFQ potential. We found that it is impossible to construct a double-well potential if we choose the wrong initial condition. For a qubit application, n must be a small odd integer and the best choice would be n = 1. We also provide a precise and efficient numerical method for calculating the energy spectrum of the arbitrary GFQ potential; this will become useful in designing the circuitry parameters. The state control and read-out schemes are also optimized to a situation where a minimum requirement for using electronics is possible, which reduces noise from instruments directly

  3. The flux database concerted action

    International Nuclear Information System (INIS)

    Mitchell, N.G.; Donnelly, C.E.

    1999-01-01

    This paper summarizes the background to the UIR action on the development of a flux database for radionuclide transfer in soil-plant systems. The action is discussed in terms of the objectives, the deliverables and the progress achieved so far by the flux database working group. The paper describes the background to the current initiative and outlines specific features of the database and supporting documentation. Particular emphasis is placed on the proforma used for data entry, on the database help file and on the approach adopted to indicate data quality. Refs. 3 (author)

  4. Science and data science.

    Science.gov (United States)

    Blei, David M; Smyth, Padhraic

    2017-08-07

    Data science has attracted a lot of attention, promising to turn vast amounts of data into useful predictions and insights. In this article, we ask why scientists should care about data science. To answer, we discuss data science from three perspectives: statistical, computational, and human. Although each of the three is a critical component of data science, we argue that the effective combination of all three components is the essence of what data science is about.

  5. LANSCE: Los Alamos Neutron Science Center

    Energy Technology Data Exchange (ETDEWEB)

    Kippen, Karen Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-11-02

    The principle goals of this project is to increase flux and improve resolution for neutron energies above 1 keV for nuclear physics experiments; and preserve current strong performance at thermal energies for material science.

  6. Black branes in flux compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Torroba, Gonzalo; Wang, Huajia

    2013-10-01

    We construct charged black branes in type IIA flux compactifications that are dual to (2 + 1)-dimensional field theories at finite density. The internal space is a general Calabi-Yau manifold with fluxes, with internal dimensions much smaller than the AdS radius. Gauge fields descend from the 3-form RR potential evaluated on harmonic forms of the Calabi-Yau, and Kaluza-Klein modes decouple. Black branes are described by a four-dimensional effective field theory that includes only a few light fields and is valid over a parametrically large range of scales. This effective theory determines the low energy dynamics, stability and thermodynamic properties. Tools from flux compactifications are also used to construct holographic CFTs with no relevant scalar operators, that can lead to symmetric phases of condensed matter systems stable to very low temperatures. The general formalism is illustrated with simple examples such as toroidal compactifications and manifolds with a single size modulus. We initiate the classification of holographic phases of matter described by flux compactifications, which include generalized Reissner-Nordstrom branes, nonsupersymmetric AdS2×R2 and hyperscaling violating solutions.

  7. High flux compact neutron generators

    International Nuclear Information System (INIS)

    Reijonen, J.; Lou, T.-P.; Tolmachoff, B.; Leung, K.-N.; Verbeke, J.; Vujic, J.

    2001-01-01

    Compact high flux neutron generators are developed at the Lawrence Berkeley National Laboratory. The neutron production is based on D-D or D-T reaction. The deuterium or tritium ions are produced from plasma using either a 2 MHz or 13.56 MHz radio frequency (RF) discharge. RF-discharge yields high fraction of atomic species in the beam which enables higher neutron output. In the first tube design, the ion beam is formed using a multiple hole accelerator column. The beam is accelerated to energy of 80 keV by means of a three-electrode extraction system. The ion beam then impinges on a titanium target where either the 2.4 MeV D-D or 14 MeV D-T neutrons are generated. The MCNP computation code has predicted a neutron flux of ∼10 11 n/s for the D-D reaction at beam intensity of 1.5 A at 150 kV. The neutron flux measurements of this tube design will be presented. Recently new compact high flux tubes are being developed which can be used for various applications. These tubes also utilize RF-discharge for plasma generation. The design of these tubes and the first measurements will be discussed in this presentation

  8. CARVE: L1 In-situ Carbon and CH4 Flux and Meteorology at EC Towers, Alaska, 2011-2015

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides ground in situ flux and meteorological science data from fixed instruments at three eddy covariance tower sites located in the Alaskan Arctic...

  9. Science in Science Fiction.

    Science.gov (United States)

    Allday, Jonathan

    2003-01-01

    Offers some suggestions as to how science fiction, especially television science fiction programs such as "Star Trek" and "Star Wars", can be drawn into physics lessons to illuminate some interesting issues. (Author/KHR)

  10. Flavour mixings in flux compactifications

    International Nuclear Information System (INIS)

    Buchmuller, Wilfried; Schweizer, Julian

    2017-01-01

    A multiplicity of quark-lepton families can naturally arise as zero-modes in flux compactifications. The flavour structure of quark and lepton mass matrices is then determined by the wave function profiles of the zero-modes. We consider a supersymmetric SO(10) x U(1) model in six dimensions compactified on the orbifold T 2 =Z 2 with Abelian magnetic flux. A bulk 16-plet charged under the U(1) provides the quark-lepton generations whereas two uncharged 10-plets yield two Higgs doublets. Bulk anomaly cancellation requires the presence of additional 16- and 10-plets. The corresponding zero-modes form vectorlike split multiplets that are needed to obtain a successful flavour phenomenology. We analyze the pattern of flavour mixings for the two heaviest families of the Standard Model and discuss possible generalizations to three and more generations.

  11. Flux through a Markov chain

    International Nuclear Information System (INIS)

    Floriani, Elena; Lima, Ricardo; Ourrad, Ouerdia; Spinelli, Lionel

    2016-01-01

    Highlights: • The flux through a Markov chain of a conserved quantity (mass) is studied. • Mass is supplied by an external source and ends in the absorbing states of the chain. • Meaningful for modeling open systems whose dynamics has a Markov property. • The analytical expression of mass distribution is given for a constant source. • The expression of mass distribution is given for periodic or random sources. - Abstract: In this paper we study the flux through a finite Markov chain of a quantity, that we will call mass, which moves through the states of the chain according to the Markov transition probabilities. Mass is supplied by an external source and accumulates in the absorbing states of the chain. We believe that studying how this conserved quantity evolves through the transient (non-absorbing) states of the chain could be useful for the modelization of open systems whose dynamics has a Markov property.

  12. Superconducting flux flow digital circuits

    International Nuclear Information System (INIS)

    Martens, J.S.; Zipperian, T.E.; Hietala, V.M.; Ginley, D.S.; Tigges, C.P.; Phillips, J.M.; Siegal, M.P.

    1993-01-01

    The authors have developed a family of digital logic circuits based on superconducting flux flow transistors that show high speed, reasonable signal levels, large fan-out, and large noise margins. The circuits are made from high-temperature superconductors (HTS) and have been shown to operate at over 90 K. NOR gates have been demonstrated with fan-outs of more than 5 and fully loaded switching times less than a fixture-limited 50 ps. Ring-oscillator data suggest inverter delay times of about 40ps when using a 3-μm linewidths. Simple flip-flops have also been demonstrated showing large noise margins, response times of less than 30 ps, and static power dissipation on the order of 30 nW. Among other uses, this logic family is appropriate as an interface between logic families such as single flux quantum and conventional semiconductor logic

  13. Latest developments in advanced network management and cross-sharing of next-generation flux stations

    Science.gov (United States)

    Burba, George; Johnson, Dave; Velgersdyk, Michael; Begashaw, Israel; Allyn, Douglas

    2016-04-01

    be merged into a single quality-control file (v) Multiple flux stations can be linked into an automated time-synchronized network (vi) Flux network managers, or PI's, can see all stations in real-time, including fluxes, supporting data, automated reports, and email alerts (vii) PI's can assign rights, allow or restrict access to stations and data: selected stations can be shared via rights-managed access internally or with external institutions (viii) Researchers without stations could form "virtual networks" for specific projects by collaborating with PIs from different actual networks This presentation provides detailed examples of FluxSuite currently utilized to manage two large flux networks in China (National Academy of Sciences and Agricultural Academy of Sciences), and smaller networks with stations in the USA, Germany, Ireland, Malaysia and other locations around the globe. Very latest 2016 developments and expanded functionality are also discussed.

  14. Surface fluxes in heterogeneous landscape

    Energy Technology Data Exchange (ETDEWEB)

    Bay Hasager, C.

    1997-01-01

    The surface fluxes in homogeneous landscapes are calculated by similarity scaling principles. The methodology is well establish. In heterogeneous landscapes with spatial changes in the micro scale range, i e from 100 m to 10 km, advective effects are significant. The present work focus on these effects in an agricultural countryside typical for the midlatitudes. Meteorological and satellite data from a highly heterogeneous landscape in the Rhine Valley, Germany was collected in the large-scale field experiment TRACT (Transport of pollutants over complex terrain) in 1992. Classified satellite images, Landsat TM and ERS SAR, are used as basis for roughness maps. The roughnesses were measured at meteorological masts in the various cover classes and assigned pixel by pixel to the images. The roughness maps are aggregated, i e spatially averaged, into so-called effective roughness lengths. This calculation is performed by a micro scale aggregation model. The model solves the linearized atmospheric flow equations by a numerical (Fast Fourier Transform) method. This model also calculate maps of friction velocity and momentum flux pixel wise in heterogeneous landscapes. It is indicated how the aggregation methodology can be used to calculate the heat fluxes based on the relevant satellite data i e temperature and soil moisture information. (au) 10 tabs., 49 ills., 223 refs.

  15. Neutron flux control systems validation

    International Nuclear Information System (INIS)

    Hascik, R.

    2003-01-01

    In nuclear installations main requirement is to obtain corresponding nuclear safety in all operation conditions. From the nuclear safety point of view is commissioning and start-up after reactor refuelling appropriate period for safety systems verification. In this paper, methodology, performance and results of neutron flux measurements systems validation is presented. Standard neutron flux measuring chains incorporated into the reactor protection and control system are used. Standard neutron flux measuring chain contains detector, preamplifier, wiring to data acquisition unit, data acquisition unit, wiring to display at control room and display at control room. During reactor outage only data acquisition unit and wiring and displaying at reactor control room is verified. It is impossible to verify detector, preamplifier and wiring to data acquisition recording unit during reactor refuelling according to low power. Adjustment and accurate functionality of these chains is confirmed by start-up rate (SUR) measurement during start-up tests after refuelling of the reactors. This measurement has direct impact to nuclear safety and increase operational nuclear safety level. Briefly description of each measuring system is given. Results are illustrated on measurements performed at Bohunice NPP during reactor start-up tests. Main failures and their elimination are described (Authors)

  16. Determination of Energy Fluxes Over Agricultural Surfaces

    Directory of Open Access Journals (Sweden)

    Josefina Argete

    1994-12-01

    Full Text Available An energy budget was conducted over two kinds if surfaces: grass and corn canopy. The net radiative flux and the soil heat flux were directly measured while the latent and sensible heat flux were calculated from the vertical profiles if wet and dry-bulb temperature and wind speed. The crop storage flux was also estimated. Using the gradient or aerodynamic equations, the calculated fluxes when compared to the measured fluxes in the context of an energy budget gave an SEE = 63 Wm-2 over grass and SEE = 81 Wm-2 over corn canopy. The calculated fluxes compared reasonably well with those obtained using the Penman equations.For an energy budget research with limited instrumentation, the aerodynamic method performed satisfactorily in estimating the daytime fluxes, when atmospheric conditions are fully convective, but failed when conditions were stably stratified as during nighttime.

  17. Progress in Modeling Global Atmospheric CO2 Fluxes and Transport: Results from Simulations with Diurnal Fluxes

    Science.gov (United States)

    Collatz, G. James; Kawa, R.

    2007-01-01

    Progress in better determining CO2 sources and sinks will almost certainly rely on utilization of more extensive and intensive CO2 and related observations including those from satellite remote sensing. Use of advanced data requires improved modeling and analysis capability. Under NASA Carbon Cycle Science support we seek to develop and integrate improved formulations for 1) atmospheric transport, 2) terrestrial uptake and release, 3) biomass and 4) fossil fuel burning, and 5) observational data analysis including inverse calculations. The transport modeling is based on meteorological data assimilation analysis from the Goddard Modeling and Assimilation Office. Use of assimilated met data enables model comparison to CO2 and other observations across a wide range of scales of variability. In this presentation we focus on the short end of the temporal variability spectrum: hourly to synoptic to seasonal. Using CO2 fluxes at varying temporal resolution from the SIB 2 and CASA biosphere models, we examine the model's ability to simulate CO2 variability in comparison to observations at different times, locations, and altitudes. We find that the model can resolve much of the variability in the observations, although there are limits imposed by vertical resolution of boundary layer processes. The influence of key process representations is inferred. The high degree of fidelity in these simulations leads us to anticipate incorporation of realtime, highly resolved observations into a multiscale carbon cycle analysis system that will begin to bridge the gap between top-down and bottom-up flux estimation, which is a primary focus of NACP.

  18. A multiscale mortar multipoint flux mixed finite element method

    KAUST Repository

    Wheeler, Mary Fanett

    2012-02-03

    In this paper, we develop a multiscale mortar multipoint flux mixed finite element method for second order elliptic problems. The equations in the coarse elements (or subdomains) are discretized on a fine grid scale by a multipoint flux mixed finite element method that reduces to cell-centered finite differences on irregular grids. The subdomain grids do not have to match across the interfaces. Continuity of flux between coarse elements is imposed via a mortar finite element space on a coarse grid scale. With an appropriate choice of polynomial degree of the mortar space, we derive optimal order convergence on the fine scale for both the multiscale pressure and velocity, as well as the coarse scale mortar pressure. Some superconvergence results are also derived. The algebraic system is reduced via a non-overlapping domain decomposition to a coarse scale mortar interface problem that is solved using a multiscale flux basis. Numerical experiments are presented to confirm the theory and illustrate the efficiency and flexibility of the method. © EDP Sciences, SMAI, 2012.

  19. Numerical Simulations of a Flux Rope Ejection

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Coronal mass ejections (CMEs) are the most violent phenomena observed on the Sun. One of the most successful models to explain CMEs is the flux rope ejection model, where a magnetic flux rope is expelled from the solar corona after a long phase along which the flux rope stays in equilibrium while ...

  20. Surface fluxes over natural landscapes using scintillometry

    NARCIS (Netherlands)

    Meijninger, W.M.L.

    2003-01-01

    Motivated by the demand for reliable area-averaged fluxes associated with natural landscapes this thesis investigates a relative new measurement technique known as the scintillation method. For homogeneous areas the surface fluxes can be derived with reasonable accuracy. However, fluxes

  1. Models of Flux Tubes from Constrained Relaxation

    Indian Academy of Sciences (India)

    tribpo

    Equilibria corresponding to the energy extrema while conserving these invariants for parallel flows yield three classes of ... parallel heat flux, due to the boundary condition Β · n = 0, that the total energy, is conserved. In all HR, K, S, and the total mass, ... Zero net current flux tubes are qualitatively similar to the flux tube with ...

  2. Surface energy budget and turbulent fluxes at Arctic terrestrial sites

    Science.gov (United States)

    Grachev, Andrey; Persson, Ola; Uttal, Taneil; Konopleva-Akish, Elena; Crepinsek, Sara; Cox, Christopher; Fairall, Christopher; Makshtas, Alexander; Repina, Irina

    2017-04-01

    imbalance magnitude. All turbulent fluxes are highly correlated with net radiation because this balance between solar and longwave radiation is the principal energy source for daytime surface warming, evaporation, and photosynthesis. We find that turbulent fluxes of carbon dioxide and sensible heat are closely linked and, on average, change sign synchronously during the diurnal and annual cycles. The work is supported by the NOAA Climate Program Office, the U.S. National Science Foundation (NSF) with award ARC 11-07428, and by the U.S. Civilian Research & Development Foundation (CRDF) with award RUG1-2976-ST-10.

  3. Science in Computational Sciences

    Directory of Open Access Journals (Sweden)

    Jameson Cerrosen

    2012-12-01

    Full Text Available The existing theory in relation to science presents the physics as an ideal, although many sciences not approach the same, so that the current philosophy of science-Theory of Science- is not much help when it comes to analyze the computer science, an emerging field of knowledge that aims investigation of computers, which are included in the materialization of the ideas that try to structure the knowledge and information about the world. Computer Science is based on logic and mathematics, but both theoretical research methods and experimental follow patterns of classical scientific fields. Modeling and computer simulation, as a method, are specific to the discipline and will be further developed in the near future, not only applied to computers but also to other scientific fields. In this article it is analyze the aspects of science in computer science, is presenting an approach to the definition of science and the scientific method in general and describes the relationships between science, research, development and technology.

  4. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 121; Issue 6. An assessment of the FlowCapt acoustic sensor for measuring snowdrift in the Indian Himalayas. R K Das P ... However, in the absence of conventional snow gauges for validation, the quality of the absolute snow flux data could not be ascertained.

  5. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 115; Issue 4. Monsoon control on trace metal fluxes in the deep Arabian Sea. T M Balakrishnan Nair. Special Section on: Material exchanges at marine boundaries and surface ocean processes: Forcings and feedbacks Volume 115 Issue 4 August 2006 pp 461-472 ...

  6. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    T M Balakrishnan Nair. Articles written in Journal of Earth System Science. Volume 115 Issue 4 August 2006 pp 461-472 Special Section on: Material exchanges at marine boundaries and surface ocean processes: Forcings and feedbacks. Monsoon control on trace metal fluxes in the deep Arabian Sea · T M Balakrishnan ...

  7. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Keywords. Ozone; solar flux; anti-weekend effect; coastal site; statistical approach; atmospheric sciences; climate; data analysis. ... In other seasons, wind reaches the observation site from less polluted landmasses and the Bay of Bengal, thereby considerably reducing the pollution load. On the contrary, ozone build-up was ...

  8. Flux of Cadmium through Euphausiids

    International Nuclear Information System (INIS)

    Benayoun, G.; Fowler, S.W.; Oregioni, B.

    1976-01-01

    Flux of the heavy metal cadmium through the euphausiid Meganyctiphanes norvegica was examined. Radiotracer experiments showed that cadmium can be accumulated either directly from water or through the food chain. When comparing equilibrium cadmium concentration factors based on stable element measurements with those obtained from radiotracer experiments, it is evident that exchange between cadmium in the water and that in euphausiid tissue is a relatively slow process, indicating that, in the long term, ingestion of cadmium will probably be the more important route for the accumulation of this metal. Approximately 10% of cadmium ingested by euphausiids was incorporated into internal tissues when the food source was radioactive Artemia. After 1 month cadmium, accumulated directly from water, was found to be most concentrated in the viscera with lesser amounts in eyes, exoskeleton and muscle, respectively. Use of a simple model, based on the assumption that cadmium taken in by the organism must equal cadmium released plus that accumulated in tissue, allowed assessment of the relative importance of various metabolic parameters in controlling the cadmium flux through euphausiids. Fecal pellets, due to their relatively high rate of production and high cadmium content, accounted for 84% of the total cadmium flux through M. norvegica. Comparisons of stable cadmium concentrations in natural euphausiid food and the organism's resultant fecal pellets indicate that the cadmium concentration in ingested material was increased nearly 5-fold during its passage through the euphausiid. From comparisons of all routes by which cadmium can be released from M. norvegica to the water column, it is concluded that fecal pellet deposition represents the principal mechanism effecting the downward vertical transport of cadmium by this species. (author)

  9. Measurement of absolute neutron flux in LWSCR based on the nuclear track method

    International Nuclear Information System (INIS)

    Sadeghzadeh, J.; Nassiri Mofakham, N.; Khajehmiri, Z.

    2012-01-01

    Highlights: ► Up to now the spectral parameters of thermal neutrons are measured with activation foils that are not always reliable in low flux systems. ► We applied a solid state nuclear track detector to measure the absolute neutron flux in the light water sub-critical reactor (LWSCR). ► Experiments concerning fission track detecting were performed and were investigated using the Monte Carlo code MCNP. ► The neutron fluxes obtained in experiment are in fairly good agreement with the results obtained by MCNP. - Abstract: In the present paper, a solid state nuclear track detector is applied to measure the absolute neutron flux in the light water sub-critical reactor (LWSCR) in Nuclear Science and Technology Research Institute (NSTRI). Up to now, the spectral parameters of thermal neutrons have been measured with activation foils that are not always reliable in low flux systems. The method investigated here is the irradiation method. Experiments concerning fission track detecting were performed. The experiment including neutron flux calculation method has also been investigated using the Monte Carlo code MCNP. The analysis shows that the values of neutron flux obtained by experiment are in fairly good agreement with the results obtained by MCNP. Thus, this method may be able to predict the absolute value of neutron flux at LWSCR and other similar reactors.

  10. Four-collector flux sensor

    International Nuclear Information System (INIS)

    Wiegand, W.J. Jr.; Bullis, R.H.; Mongeon, R.J.

    1980-01-01

    A flowmeter based on ion drift techniques was developed for measuring the rate of flow of a fluid through a given cross-section. Ion collectors are positioned on each side of an immediately adjacent to ion source. When air flows axially through the region in which ions are produced and appropriate electric fields are maintained between the collectors, an electric current flows to each collector due to the net motion of the ions. The electric currents and voltages and other parameters which define the flow are combined in an electric circuit so that the flux of the fluid can be determined. (DN)

  11. Decadal Changes in Surface Radiative Fluxes

    Science.gov (United States)

    Wild, M.

    2009-05-01

    Recent evidence suggests that radiative fluxes incident at the Earth surface are not stable over time but undergo significant changes on decadal timescales. This is not only found in the thermal spectral range, where an increase in the downwelling flux is expected with the increasing greenhouse effect, but also in the solar range. Observations suggest that surface solar radiation, after decades of decline ("global dimming"), reversed into a "brightening" since the mid-1980s at widespread locations. This presentation gives an update on recent investigations related to the decadal variations in these fluxes, based on both observational and modeling approaches. Updated observational data, archived at the Global Energy Balance Archive (GEBA) at ETH Zurich, suggest a continuation of surface solar brightening beyond the year 2000 at numerous locations, yet less pronounced and coherent than during the 1990s, with more regions with no clear changes or declines. Current global climate models as used in the IPCC-AR4 report typically do not reproduce the observed decadal variations to their full extent. Modeling attempts to improve this situation are under way at ETH, based on a global climate model which includes a sophisticated interactive treatment of aerosol and cloud microphysics (ECHAM5-HAM). Further the impact of the decadal changes in surface radiative forcings on different aspects of the global climate system and climate change is discussed, such as 20th century day- and nighttime warming, evapotranspiration changes and the varying intensity of the hydrological cycle as well as the terrestrial carbon cycle. Selected related references: Wild, M., and Co-authors, 2005: From dimming to brightening: Decadal changes in solar radiation at the Earth's surface. Science, 308, 847-850 Wild, M., 2007: Decadal changes in surface radiative fluxes and their importance in the context of global climate change, in: Climate Variability and Extremes during the Past 100 years, Advances

  12. Tokamak disruption heat flux simulator

    International Nuclear Information System (INIS)

    Langhoff, M.; Hess, G.; Gahl, J.; Ingram, R.

    1990-01-01

    A coaxial plasma gun system, operating in the deflagration mode, has been built and fired at the University of New Mexico. This system, powered by a 100 kJ capacitor bank, was designed to give a variable pulse length of approximately 50-100 us. The gun is intended to deliver to a target an energy deposition density of 1 kJ per cm 2 via impact with a deuterium plasma possessing a highly directed energy. This system should simulate on the target, over an area of approximately 10 cm 2 , the heat flux of a tokamak plasma disruption on plasma facing components. Current diagnostics for the system are rather rudimentary but sufficient for determination of plasma pulse characteristics and energy transfer to target. Electrical measurements include bank voltage measured via resistive voltage dividers, and bank current measured via Rogowski coil. The shape of the plasma, its position relative to the target area, and the final impact area, is determined via open-shutter photography and the use of witness plates. Total energy deposited onto targets will be determined through simple calorimetry and careful target mass measurements. Preliminary results describing the ablation of carbon targets exposed to disruption like heat fluxes will be presented as well as a description of the experimental apparatus

  13. Neutron flux enhancement at LASREF

    International Nuclear Information System (INIS)

    Sommer, W.F.; Ferguson, P.D.; Wechsler, M.S.

    1991-01-01

    The accelerator at the Los Alamos Meson Physics Facility produces a 1-mA beam of protons at an energy of 800 MeV. Since 1985, the Los Alamos Spallation Radiation Effects Facility (LASREF) has made use of the neutron flux that is generated as the incident protons interact with the nuclei in targets and a copper beam stop. A variety of basic and applied experiments in radiation damage and radiation effects have been completed. Recent studies indicate that the flux at LASREF can be increased by at least a factor of ten from the present level of about 5 E+17 m -2 s -1 . This requires changing the beam-stop material from Cu to W and optimizing the geometry of the beam-target interaction region. These studies are motivated by the need for a large volume, high energy, and high intensity neutron source in the development of materials for advanced energy concepts such as fusion reactors. 18 refs., 7 figs., 2 tabs

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

    Science.gov (United States)

    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 (1.5advantage of a more accurate calculation of diffusive fluxes especially for redox dependent elements. Model results showed that in 50 cm above the sediment vertical fluxes are changing largely while in chamber experiments they are averaged. As a result, each of the methods has its disadvantages and the main facing us question is - which value should be taken for calculation the balance? This research is funded by VISTA - a basic research program and

  15. Science of science.

    Science.gov (United States)

    Fortunato, Santo; Bergstrom, Carl T; Börner, Katy; Evans, James A; Helbing, Dirk; Milojević, Staša; Petersen, Alexander M; Radicchi, Filippo; Sinatra, Roberta; Uzzi, Brian; Vespignani, Alessandro; Waltman, Ludo; Wang, Dashun; Barabási, Albert-László

    2018-03-02

    Identifying fundamental drivers of science and developing predictive models to capture its evolution are instrumental for the design of policies that can improve the scientific enterprise-for example, through enhanced career paths for scientists, better performance evaluation for organizations hosting research, discovery of novel effective funding vehicles, and even identification of promising regions along the scientific frontier. The science of science uses large-scale data on the production of science to search for universal and domain-specific patterns. Here, we review recent developments in this transdisciplinary field. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  16. Carbon dioxide, water vapour and energy fluxes over a semi ...

    Indian Academy of Sciences (India)

    42

    vapour fluxes in Mangrove ecosystems, Sundarbans (India). The above observations are. 57 .... with the help of PAR. 115 sensor. Soil heat flux plates were used for the measurement of soil heat flux. ..... where Rn is net radiation, G is the soil heat flux, H is sensible heat flux and LE is the latent. 233 heat flux. 234. We have ...

  17. Science Smiles

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education. Science Smiles. Articles in Resonance – Journal of Science Education. Volume 1 Issue 4 April 1996 pp 4-4 Science Smiles. Chief Editor's column / Science Smiles · R K Laxman · More Details Fulltext PDF. Volume 1 Issue 5 May 1996 pp 3-3 Science Smiles.

  18. Pyrolytic graphite gauge for measuring heat flux

    Science.gov (United States)

    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.

  19. Local rectification of heat flux

    Science.gov (United States)

    Pons, M.; Cui, Y. Y.; Ruschhaupt, A.; Simón, M. A.; Muga, J. G.

    2017-09-01

    We present a chain-of-atoms model where heat is rectified, with different fluxes from the hot to the cold baths located at the chain boundaries when the temperature bias is reversed. The chain is homogeneous except for boundary effects and a local modification of the interactions at one site, the “impurity”. The rectification mechanism is due here to the localized impurity, the only asymmetrical element of the structure, apart from the externally imposed temperature bias, and does not rely on putting in contact different materials or other known mechanisms such as grading or long-range interactions. The effect survives if all interaction forces are linear except the ones for the impurity.

  20. Nuclear transmutation by flux compression

    International Nuclear Information System (INIS)

    Seifritz, W.

    2001-01-01

    A new idea for the transmutation of minor actinides, long (and even short) lived fission products is presented. It is based an the property of neutron flux compression in nuclear (fast and/or thermal) reactors possessing spatially non-stationary critical masses. An advantage factor for the burn-up fluence of the elements to be transmuted in the order of magnitude of 100 and more is obtainable compared with the classical way of transmutation. Three typical examples of such transmuters (a subcritical ringreactor with a rotating reflector, a sub-critical ring reactor with a rotating spallation source, the socalled ''pulsed energy amplifier'', and a fast burn-wave reactor) are presented and analysed with regard to this purpose. (orig.) [de

  1. Insects, infestations and nutrient fluxes

    Science.gov (United States)

    Michalzik, B.

    2012-04-01

    Forest ecosystems are characterized by a high temporal and spatial variability in the vertical transfer of energy and matter within the canopy and the soil compartment. The mechanisms and controlling factors behind canopy processes and system-internal transfer dynamics are imperfectly understood at the moment. Seasonal flux diversities and inhomogeneities in throughfall composition have been reported from coniferous and deciduous forests, and in most cases leaf leaching has been considered as principle driver for differences in the amount and quality of nutrients and organic compounds (Tukey and Morgan 1963). Since herbivorous insects and the processes they initiate received less attention in past times, ecologists now emphasize the need for linking biological processes occurring in different ecosystem strata to explain rates and variability of nutrient cycling (Bardgett et al. 1998, Wardle et al. 2004). Consequently, herbivore insects in the canopies of forests are increasingly identified to play an important role for the (re)cycling and availability of nutrients, or, more generally, for the functioning of ecosystems not only in outbreak situations but also at endemic (non-outbreak) density levels (Stadler et al. 2001, Hunter et al. 2003). Before, little attention was paid to insect herbivores when quantifying element and energy fluxes through ecosystems, although the numerous and different functions insects fulfill in ecosystems (e.g. as pollinators, herbivores or detritivores) were unanimously recognized (Schowalter 2000). Amongst the reasons for this restraint was the argument that the total biomass of insects tends to be relatively low compared to the biomass of trees or the pool of soil organic matter (Ohmart et al. 1983). A second argument which was put forward to justify the inferior role of insects in nutrient cycling were the supposed low defoliation losses between 5-10% of the annual leaf biomass, or net primary production, due to insect herbivory under

  2. Quantifying trace element and isotope fluxes at the ocean–sediment boundary: a review

    Science.gov (United States)

    Berelson, William M.; Severmann, Silke

    2016-01-01

    Quantifying fluxes of trace elements and their isotopes (TEIs) at the ocean's sediment–water boundary is a pre-eminent challenge to understand their role in the present, past and future ocean. There are multiple processes that drive the uptake and release of TEIs, and properties that determine their rates are unevenly distributed (e.g. sediment composition, redox conditions and (bio)physical dynamics). These factors complicate our efforts to find, measure and extrapolate TEI fluxes across ocean basins. GEOTRACES observations are unveiling the oceanic distributions of many TEIs for the first time. These data evidence the influence of the sediment–water boundary on many TEI cycles, and underline the fact that our knowledge of the source–sink fluxes that sustain oceanic distributions is largely missing. Present flux measurements provide low spatial coverage and only part of the empirical basis needed to predict TEI flux variations. Many of the advances and present challenges facing TEI flux measurements are linked to process studies that collect sediment cores, pore waters, sinking material or seawater in close contact with sediments. However, such sampling has not routinely been viable on GEOTRACES expeditions. In this article, we recommend approaches to address these issues: firstly, with an interrogation of emergent data using isotopic mass-balance and inverse modelling techniques; and secondly, by innovating pursuits of direct TEI flux measurements. We exemplify the value of GEOTRACES data with a new inverse model estimate of benthic Al flux in the North Atlantic Ocean. Furthermore, we review viable flux measurement techniques tailored to the sediment–water boundary. We propose that such activities are aimed at regions that intersect the GEOTRACES Science Plan on the basis of seven criteria that may influence TEI fluxes: sediment provenance, composition, organic carbon supply, redox conditions, sedimentation rate, bathymetry and the benthic nepheloid

  3. Heat Flux Inhibition by Whistlers: Experimental Confirmation

    International Nuclear Information System (INIS)

    Eichler, D.

    2002-01-01

    Heat flux in weakly magnetized collisionless plasma is, according to theoretical predictions, limited by whistler turbulence that is generated by heat flux instabilities near threshold. Observations of solar wind electrons by Gary and coworkers appear to confirm the limit on heat flux as being roughly the product of the magnetic energy density and the electron thermal velocity, in agreement with prediction (Pistinner and Eichler 1998)

  4. Science or Science Fiction?

    DEFF Research Database (Denmark)

    Lefsrud, Lianne M.; Meyer, Renate

    2012-01-01

    This paper examines the framings and identity work associated with professionals’ discursive construction of climate change science, their legitimation of themselves as experts on ‘the truth’, and their attitudes towards regulatory measures. Drawing from survey responses of 1077 professional......, legitimation strategies, and use of emotionality and metaphor. By linking notions of the science or science fiction of climate change to the assessment of the adequacy of global and local policies and of potential organizational responses, we contribute to the understanding of ‘defensive institutional work...

  5. Pursuing nuclear energy with no nuclear contamination - from neutron flux reactor to deuteron flux reactor

    International Nuclear Information System (INIS)

    Li, X. Z.; Wei, Q. M.; Liu, B.; Zhu, X. G.; Ren, S. L.

    2007-01-01

    -free channel in the deuteron-deuteron fusion reaction. Even if polarized deuteron has long enough life-time to keep its polarity in hot fusion plasma, there is still the probability to have the neutron emission channel from deuteron-deuteron fusion. The neutron emission in hot plasma containing deuterons is inevitable. Isomer Hf-178 was proposed to reduce the neutron emission in terms of gamma decay controlled by X-ray. Although its reality is still in question, the resonance plays key role in this concept as well. Condensed matter nuclear science provided another chance to approach nuclear energy with no nuclear contamination. Selective resonant tunneling would select only the neutron free channel. There are five major steps in the past 17 years: (1) Selective Resonant tunneling model has been successful to explain the 3 major puzzles in cold fusion proposed by nuclear physicist(i.e. penetration of Coulomb barrier, no neutron emission, no gamma radiation), and successful also to explain the 3 major cross-section data in hot fusion(i.e. d+t, d+d, d+He 3 ). The Nobel prize laureate, B. Josephson of Cambridge University, cited this theory in the famous Lindau Meeting (2004).[1,2] (2) Deuteron flux through the palladium surface at specific temperature was found correlated with heat flow in various experiments in China, Switzerland, Japan, France and Italy.[3,4] (3) The nuclear products have been confirmed in a series of nuclear transmutation experiments using deuterium flux permeating through the thin film on the palladium surface.[5] (4) Distinct from the beam-target experiment, a special procedure was proposed to search this resonance between lattice energy level and nuclear energy level. (5) Instead of the electrolytic cell, the gas loading technique has been used. It led to the discovery of the temperature of these resonances which may be as high as 1000 degree C. This would change greatly the usage of this nuclear energy. We may propose the future subjects of study as

  6. Dimensional reduction of a generalized flux problem

    International Nuclear Information System (INIS)

    Moroz, A.

    1992-01-01

    In this paper, a generalized flux problem with Abelian and non-Abelian fluxes is considered. In the Abelian case we shall show that the generalized flux problem for tight-binding models of noninteracting electrons on either 2n- or (2n + 1)-dimensional lattice can always be reduced to an n-dimensional hopping problem. A residual freedom in this reduction enables one to identify equivalence classes of hopping Hamiltonians which have the same spectrum. In the non-Abelian case, the reduction is not possible in general unless the flux tensor factorizes into an Abelian one times are element of the corresponding algebra

  7. [Effects of straw mulching on CO2 flux in wintry fallow paddy field].

    Science.gov (United States)

    Yin, Chun-mei; Xie, Xiao-li; Wang, Kai-rong

    2008-01-01

    This paper studied the effects of straw mulching on the CO2 flux in a wintry fallow paddy field at Taoyuan Agro-ecological Station, Chinese Academy of Sciences. The results showed that the effects of straw mulching mainly exerted in two ways. First, it positively affected soil temperature, making the CO2 flux increased obviously. Straw mulching gave a net emission of 2.68 g CO2 x m(-2) x d(-1), while no mulching gave a net fixation of 1.99 g CO2 x m(-2) x d(-1), the difference between them being very significant (P mulching decreased the biomass of weeds and the photosynthetically active radiation they absorbed, which in turn resulted in an increase of CO2 flux. Under straw mulching, the water content in surface soil layer (0-15 cm) increased by 9% or more, but no significant change was observed in CO2 flux.

  8. CERES Fast Longwave And SHortwave Radiative Flux (FLASHFlux) Version4A.

    Science.gov (United States)

    Sawaengphokhai, P.; Stackhouse, P. W., Jr.; Kratz, D. P.; Gupta, S. K.

    2017-12-01

    The agricultural, renewable energy management, and science communities need global surface and top-of-atmosphere (TOA) radiative fluxes on a low latency basis. The Clouds and Earth's Radiant Energy System (CERES) FLASHFlux (Fast Longwave and SHortwave radiative Flux) data products address this need by enhancing the speed of CERES processing using simplified calibration and parameterized model of surface fluxes to provide a daily global radiative fluxes data set within one week of satellite observations. The CERES FLASHFlux provides two data products: 1) an overpass swath Level 2 Single Scanner Footprint (SSF) data products separately for both Aqua and Terra observations, and 2) a daily Level 3 Time Interpolated and Spatially Averaged (TISA) 1o x 1o gridded data that combines Aqua and Terra observations. The CERES FLASHFlux data product is being promoted to Version4A. Updates to FLASHFlux Version4A include a new cloud retrieval algorithm and an improved shortwave surface flux parameterization. We inter-compared FLASHFlux Version4A, FLASHFlux Version3C, CERES Edition 4 Syn1Deg and at the monthly scale CERES Edition4 EBAF (Energy Balanced and Filled) Top-of-Atmosphere and Edition 4 Surface EBAF fluxes to evaluate these improvements. We also analyze the impact of the new inputs and cloud algorithm to the surface shortwave and longwave radiative fluxes using ground sites measurement provided by CAVE (CERES/ARM Validation Experiment).

  9. Association between anomalies of moisture flux and extreme runoff events in the south-eastern Alps

    Czech Academy of Sciences Publication Activity Database

    Müller, Miloslav; Kašpar, Marek

    2011-01-01

    Roč. 11, č. 3 (2011), s. 915-920 ISSN 1561-8633 Institutional research plan: CEZ:AV0Z30420517 Keywords : moisture flux * extreme precipitation * seasonality of heavy rains Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.983, year: 2011 http://www.nat-hazards-earth-syst-sci.net/11/915/2011/

  10. Satellite evidence for no change in terrestrial latent heat flux in the ...

    Indian Academy of Sciences (India)

    tion transpiration and regulates climate change by altering the exchange of terrestrial energy, water and carbon .... by the Global Inventory Modeling and Mapping. Studies (GIMMS) group at NASA GSFC at a spa- ..... meter (AMSR) Science Team meeting; Earth Observer. 13 3–9. Mahrt L 2010 Computing turbulent fluxes ...

  11. Satellite evidence for no change in terrestrial latent heat flux in the ...

    Indian Academy of Sciences (India)

    Satellite evidence for no change in terrestrial latent heat flux in the Three-River Headwaters region of China over the past three decades. Yunjun Yao1, Shaohua Zhao2,∗, Huawei Wan2, Yuhu Zhang3,. Bo Jiang1, Kun Jia1, Meng Liu4 and Jinhui Wu1. 1State Key Laboratory of Remote Sensing Science, School of ...

  12. Self-organization in magnetic flux ropes

    Science.gov (United States)

    Lukin, Vyacheslav S.

    2014-06-01

    This cross-disciplinary special issue on 'Self-organization in magnetic flux ropes' follows in the footsteps of another collection of manuscripts dedicated to the subject of magnetic flux ropes, a volume on 'Physics of magnetic flux ropes' published in the American Geophysical Union's Geophysical Monograph Series in 1990 [1]. Twenty-four years later, this special issue, composed of invited original contributions highlighting ongoing research on the physics of magnetic flux ropes in astrophysical, space and laboratory plasmas, can be considered an update on our state of understanding of this fundamental constituent of any magnetized plasma. Furthermore, by inviting contributions from research groups focused on the study of the origins and properties of magnetic flux ropes in a variety of different environments, we have attempted to underline both the diversity of and the commonalities among magnetic flux ropes throughout the solar system and, indeed, the universe. So, what is a magnetic flux rope? The answer will undoubtedly depend on whom you ask. A flux rope can be as narrow as a few Larmor radii and as wide as the Sun (see, e.g., the contributions by Heli Hietala et al and by Angelous Vourlidas). As described below by Ward Manchester IV et al , they can stretch from the Sun to the Earth in the form of interplanetary coronal mass ejections. Or, as in the Swarthmore Spheromak Experiment described by David Schaffner et al , they can fit into a meter-long laboratory device tended by college students. They can be helical and line-tied (see, e.g., Walter Gekelman et al or J Sears et al ), or toroidal and periodic (see, e.g., John O'Bryan et al or Philippa Browning et al ). They can form in the low plasma beta environment of the solar corona (Tibor Török et al ), the order unity beta plasmas of the solar wind (Stefan Eriksson et al ) and the plasma pressure dominated stellar convection zones (Nicholas Nelson and Mark Miesch). In this special issue, Setthivoine You

  13. Opportunities in Neutron Science

    Science.gov (United States)

    Fernandez-Baca, Jaime

    2010-03-01

    National Laboratories often have unique facilities that cannot be normally found at universities, and that provide unique opportunities to perform research using world class instrumentation in collaboration with teams of experts. This synergy of expertise and world-class facilities also offers unique opportunities for mentoring and training of students in settings different from the university environment. In this talk I will discuss the opportunities of scientific research, mentoring and training at the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. The SNS is the world's most intense pulsed accelerator-based neutron source, the HFIR is the highest flux reactor-based neutron source for condensed matter research in the United States, the combination of these provides neutron scattering capabilities unavailable anywhere else in the world. The SNS and the HFIR at ORNL are funded by the Division of Scientific User Facilities, Office of Basic Energy Sciences, US. Department of Energy.

  14. Surface Flux Modeling for Air Quality Applications

    Directory of Open Access Journals (Sweden)

    Limei Ran

    2011-08-01

    Full Text Available For many gasses and aerosols, dry deposition is an important sink of atmospheric mass. Dry deposition fluxes are also important sources of pollutants to terrestrial and aquatic ecosystems. The surface fluxes of some gases, such as ammonia, mercury, and certain volatile organic compounds, can be upward into the air as well as downward to the surface and therefore should be modeled as bi-directional fluxes. Model parameterizations of dry deposition in air quality models have been represented by simple electrical resistance analogs for almost 30 years. Uncertainties in surface flux modeling in global to mesoscale models are being slowly reduced as more field measurements provide constraints on parameterizations. However, at the same time, more chemical species are being added to surface flux models as air quality models are expanded to include more complex chemistry and are being applied to a wider array of environmental issues. Since surface flux measurements of many of these chemicals are still lacking, resistances are usually parameterized using simple scaling by water or lipid solubility and reactivity. Advances in recent years have included bi-directional flux algorithms that require a shift from pre-computation of deposition velocities to fully integrated surface flux calculations within air quality models. Improved modeling of the stomatal component of chemical surface fluxes has resulted from improved evapotranspiration modeling in land surface models and closer integration between meteorology and air quality models. Satellite-derived land use characterization and vegetation products and indices are improving model representation of spatial and temporal variations in surface flux processes. This review describes the current state of chemical dry deposition modeling, recent progress in bi-directional flux modeling, synergistic model development research with field measurements, and coupling with meteorological land surface models.

  15. Sensorless Direct Flux Vector Control of Synchronous Reluctance Motors Including Standstill, MTPA and Flux Weakening

    OpenAIRE

    Yousefi-Talouki, Arzhang; Pescetto, Paolo; Pellegrino, Gian-Mario Luigi

    2017-01-01

    This paper proposes a sensorless direct flux vector control scheme for synchronous reluctance motor drives. Torque is controlled at constant switching frequency, via the closed loop regulation of the stator flux linkage vector and of the current component in quadrature with it, using the stator flux oriented reference frame. A hybrid flux and position observer combines back-electromotive force integration with pulsating voltage injection around zero speed. Around zero speed, the position obse...

  16. Flux compactifications, gauge algebras and De Sitter

    NARCIS (Netherlands)

    Dibitetto, Giuseppe; Linares, Roman; Roest, Diederik

    2010-01-01

    The introduction of (non-)geometric fluxes allows for N = 1 moduli stabilisation in a De Sitter vacuum. The aim of this Letter is to assess to what extent this is true in N = 4 compactifications. First we identify the correct gauge algebra in terms of gauge and (non-)geometric fluxes. We then show

  17. Neutron flux measurement by mobile detectors

    International Nuclear Information System (INIS)

    Verchain, M.

    1987-01-01

    Various incore instrumentation systems and their technological evolution are first reviewed. Then, for 1300 MWe PWR nuclear power plant, temperature and neutron flux measurement are described. Mobile fission chambers, with their large measuring range and accurate location allow a good knowledge of the core. Other incore measures are possible because of flux detector thimble tubes inserted in the reactor core [fr

  18. Fast flux module detection using matroid theory.

    Science.gov (United States)

    Reimers, Arne C; Bruggeman, Frank J; Olivier, Brett G; Stougie, Leen

    2015-05-01

    Flux balance analysis (FBA) is one of the most often applied methods on genome-scale metabolic networks. Although FBA uniquely determines the optimal yield, the pathway that achieves this is usually not unique. The analysis of the optimal-yield flux space has been an open challenge. Flux variability analysis is only capturing some properties of the flux space, while elementary mode analysis is intractable due to the enormous number of elementary modes. However, it has been found by Kelk et al. (2012) that the space of optimal-yield fluxes decomposes into flux modules. These decompositions allow a much easier but still comprehensive analysis of the optimal-yield flux space. Using the mathematical definition of module introduced by Müller and Bockmayr (2013b), we discovered useful connections to matroid theory, through which efficient algorithms enable us to compute the decomposition into modules in a few seconds for genome-scale networks. Using that every module can be represented by one reaction that represents its function, in this article, we also present a method that uses this decomposition to visualize the interplay of modules. We expect the new method to replace flux variability analysis in the pipelines for metabolic networks.

  19. EL-2 reactor: Thermal neutron flux distribution

    International Nuclear Information System (INIS)

    Rousseau, A.; Genthon, J.P.

    1958-01-01

    The flux distribution of thermal neutrons in EL-2 reactor is studied. The reactor core and lattices are described as well as the experimental reactor facilities, in particular, the experimental channels and special facilities. The measurement shows that the thermal neutron flux increases in the central channel when enriched uranium is used in place of natural uranium. However the thermal neutron flux is not perturbed in the other reactor channels by the fuel modification. The macroscopic flux distribution is measured according the radial positioning of fuel rods. The longitudinal neutron flux distribution in a fuel rod is also measured and shows no difference between enriched and natural uranium fuel rods. In addition, measurements of the flux distribution have been effectuated for rods containing other material as steel or aluminium. The neutron flux distribution is also studied in all the experimental channels as well as in the thermal column. The determination of the distribution of the thermal neutron flux in all experimental facilities, the thermal column and the fuel channels has been made with a heavy water level of 1825 mm and is given for an operating power of 1000 kW. (M.P.)

  20. Increased heat fluxes near a forest edge

    NARCIS (Netherlands)

    Klaassen, W; van Breugel, PB; Moors, EJ; Nieveen, JP

    2002-01-01

    Observations of sensible and latent heat flux above forest downwind of a forest edge show these fluxes to be larger than the available energy over the forest. The enhancement averages to 56 W m(-2), or 16% of the net radiation, at fetches less than 400 m, equivalent to fetch to height ratios less

  1. Increased heat fluxes near a forest edge

    NARCIS (Netherlands)

    Klaassen, W.; Breugel, van P.B.; Moors, E.J.; Nieveen, J.P.

    2002-01-01

    Observations of sensible and latent heat flux above forest downwind of a forest edge show these fluxes to be larger than the available energy over the forest. The enhancement averages to 56 W mm2, or 16 f the net radiation, at fetches less than 400 m, equivalent to fetch to height ratios less than

  2. Initiation of CMEs by Magnetic Flux Emergence

    Indian Academy of Sciences (India)

    The initiation of solar Coronal Mass Ejections (CMEs) is studied in the framework of numerical magnetohydrodynamics (MHD). The initial CME model includes a magnetic flux rope in spherical, axisymmetric geometry. The initial configuration consists of a magnetic flux rope embedded in a gravitationally stratified solar ...

  3. Heat flux viscosity in collisional magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C., E-mail: cliu@pppl.gov [Princeton University, Princeton, New Jersey 08544 (United States); Fox, W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Bhattacharjee, A. [Princeton University, Princeton, New Jersey 08544 (United States); Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2015-05-15

    Momentum transport in collisional magnetized plasmas due to gradients in the heat flux, a “heat flux viscosity,” is demonstrated. Even though no net particle flux is associated with a heat flux, in a plasma there can still be momentum transport owing to the velocity dependence of the Coulomb collision frequency, analogous to the thermal force. This heat-flux viscosity may play an important role in numerous plasma environments, in particular, in strongly driven high-energy-density plasma, where strong heat flux can dominate over ordinary plasma flows. The heat flux viscosity can influence the dynamics of the magnetic field in plasmas through the generalized Ohm's law and may therefore play an important role as a dissipation mechanism allowing magnetic field line reconnection. The heat flux viscosity is calculated directly using the finite-difference method of Epperlein and Haines [Phys. Fluids 29, 1029 (1986)], which is shown to be more accurate than Braginskii's method [S. I. Braginskii, Rev. Plasma Phys. 1, 205 (1965)], and confirmed with one-dimensional collisional particle-in-cell simulations. The resulting transport coefficients are tabulated for ease of application.

  4. Anthropogenic heat flux estimation from space

    NARCIS (Netherlands)

    Chrysoulakis, Nektarios; Marconcini, Mattia; Gastellu-Etchegorry, Jean Philippe; Grimmond, C.S.B.; Feigenwinter, Christian; Lindberg, Fredrik; Frate, Del Fabio; Klostermann, Judith; Mitraka, Zina; Esch, Thomas; Landier, Lucas; Gabey, Andy; Parlow, Eberhard; Olofson, Frans

    2016-01-01

    H2020-Space project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of Copernicus Sentinels to retrieve anthropogenic heat flux, as a key component of the Urban Energy Budget (UEB). URBANFLUXES advances the current knowledge of the impacts

  5. ANthropogenic heat FLUX estimation from Space

    NARCIS (Netherlands)

    Chrysoulakis, Nektarios; Marconcini, Mattia; Gastellu-Etchegorry, Jean Philippe; Grimmong, C.S.B.; Feigenwinter, Christian; Lindberg, Fredrik; Frate, Del Fabio; Klostermann, Judith; Mi, Zina; Esch, Thomas; Landier, Lucas; Gabey, Andy; Parlow, Eberhard; Olofson, Frans

    2017-01-01

    The H2020-Space project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of Copernicus Sentinels to retrieve anthropogenic heat flux, as a key component of the Urban Energy Budget (UEB). URBANFLUXES advances the current knowledge of the

  6. Optical magnetic flux generation in superconductor

    Indian Academy of Sciences (India)

    Abstract. The generation of the magnetic flux quanta inside the superconductors is studied as a new effect to destroy ... Ultrafast phenomena; femtosecond laser; optical magnetic flux generation. PACS Nos 85.25. .... [8] M Tonouchi, M Tani, Z Wang, K Sakai, S Tomozawa, M Hangyo, Y Murakami and S. Nakashima, Jpn. J.

  7. Multi-circular flux motor

    Energy Technology Data Exchange (ETDEWEB)

    El-Kharashi, Eyhab Aly, E-mail: EyhabElkharahi@hotmail.com [Faculty of Engineering, Electrical Power and Machines Department, Ain Shams University, 1 El-Sarayat Street, Abdou Basha Square, Abbassia 11517, Cairo (Egypt)

    2011-11-15

    Highlights: {yields} The paper uses the multi-circular rotor in the switched reluctance motor to increase its output torque and its efficiency. {yields} Finite element is used to model the new SRM accurately. {yields} The Matlab/Simulink is used to dynamically model the new SRM. {yields} The paper compares the torque capability of the multi-circular rotor SRM. {yields} The new SRM produces approximately double the torque of its equivalent conventional SRM. - Abstract: The paper introduces a new type of electrical machines which has significantly high output torque. The toothed-rotor in the conventional electrical machine is replaced by a multi-circular rotor to increase the saliency and to shorten the flux loops consequently the output torque increases. The paper presents the design steps of this new type of electrical machine and also examines its performance. In addition, the paper compares the percentage increase in output torque from the proposed new electric machine to its equivalent conventional motor. Then the paper proceeds to discuss the relation between the switching on angle and the maximum speed, the torque ripples, and the efficiency.

  8. Crystal growth of emerald by flux method

    International Nuclear Information System (INIS)

    Inoue, Mikio; Narita, Eiichi; Okabe, Taijiro; Morishita, Toshihiko.

    1979-01-01

    Emerald crystals have been formed in two binary fluxes of Li 2 O-MoO 2 and Li 2 O-V 2 O 5 using the slow cooling method and the temperature gradient method under various conditions. In the flux of Li 2 O-MoO 3 carried out in the range of 2 -- 5 of molar ratios (MoO 3 /Li 2 O), emerald was crystallized in the temperature range from 750 to 950 0 C, and the suitable crystallization conditions were found to be the molar ratio of 3 -- 4 and the temperature about 900 0 C. In the flux of Li 2 O-V 2 O 5 carried out in the range of 1.7 -- 5 of molar ratios (V 2 O 5 /Li 2 O), emerald was crystallized in the temperature range from 900 to 1150 0 . The suitable crystals were obtained at the molar ratio of 3 and the temperature range of 1000 -- 1100 0 C. The crystallization temperature rised with an increase in the molar ratio of the both fluxes. The emeralds grown in two binary fluxes were transparent green, having the density of 2.68, the refractive index of 1.56, and the two distinct bands in the visible spectrum at 430 and 600nm. The emerald grown in Li 2 O-V 2 O 5 flux was more bluish green than that grown in Li 2 O-MoO 3 flux. The size of the spontaneously nucleated emerald grown in the former flux was larger than the latter, when crystallized by the slow cooling method. As for the solubility of beryl in the two fluxes, Li 2 O-V 2 O 5 flux was superior to Li 2 O-MoO 3 flux whose small solubility of SiO 2 caused an experimental problem to the temperature gradient method. The suitability of the two fluxes for the crystal growth of emerald by the flux method was discussed from the view point of various properties of above-mentioned two fluxes. (author)

  9. FluxFix: automatic isotopologue normalization for metabolic tracer analysis.

    Science.gov (United States)

    Trefely, Sophie; Ashwell, Peter; Snyder, Nathaniel W

    2016-11-25

    Isotopic tracer analysis by mass spectrometry is a core technique for the study of metabolism. Isotopically labeled atoms from substrates, such as [ 13 C]-labeled glucose, can be traced by their incorporation over time into specific metabolic products. Mass spectrometry is often used for the detection and differentiation of the isotopologues of each metabolite of interest. For meaningful interpretation, mass spectrometry data from metabolic tracer experiments must be corrected to account for the naturally occurring isotopologue distribution. The calculations required for this correction are time consuming and error prone and existing programs are often platform specific, non-intuitive, commercially licensed and/or limited in accuracy by using theoretical isotopologue distributions, which are prone to artifacts from noise or unresolved interfering signals. Here we present FluxFix ( http://fluxfix.science ), an application freely available on the internet that quickly and reliably transforms signal intensity values into percent mole enrichment for each isotopologue measured. 'Unlabeled' data, representing the measured natural isotopologue distribution for a chosen analyte, is entered by the user. This data is used to generate a correction matrix according to a well-established algorithm. The correction matrix is applied to labeled data, also entered by the user, thus generating the corrected output data. FluxFix is compatible with direct copy and paste from spreadsheet applications including Excel (Microsoft) and Google sheets and automatically adjusts to account for input data dimensions. The program is simple, easy to use, agnostic to the mass spectrometry platform, generalizable to known or unknown metabolites, and can take input data from either a theoretical natural isotopologue distribution or an experimentally measured one. Our freely available web-based calculator, FluxFix ( http://fluxfix.science ), quickly and reliably corrects metabolic tracer data for

  10. Closing the North American Carbon Budget: Continental Margin Fluxes Matter!

    Science.gov (United States)

    Najjar, R.; Benway, H. M.; Siedlecki, S. A.; Boyer, E. W.; Cai, W. J.; Coble, P. G.; Cross, J. N.; Friedrichs, M. A.; Goni, M. A.; Griffith, P. C.; Herrmann, M.; Lohrenz, S. E.; Mathis, J. T.; McKinley, G. A.; Pilskaln, C. H.; Smith, R. A.; Alin, S. R.

    2015-12-01

    Despite their relatively small surface area, continental margins are regions of intense carbon and nutrient processing, export and exchange, and thus have a significant impact on global biogeochemical cycles. In response to recommendations for regional synthesis and carbon budget estimation for North America put forth in the North American Continental Margins workshop report (Hales et al., 2008), the Ocean Carbon and Biogeochemistry (OCB) Program and North American Carbon Program (NACP) began coordinating a series of collaborative, interdisciplinary Coastal CARbon Synthesis (CCARS) research activities in five coastal regions of North America (Atlantic Coast, Pacific Coast, Gulf of Mexico, Arctic, Laurentian Great Lakes) to improve quantitative assessments of the North American carbon budget. CCARS workshops and collaborative research activities have resulted in the development of regional coastal carbon budgets based on recent literature- and model-based estimates of major carbon fluxes with estimated uncertainties. Numerous peer-reviewed papers and presentations by involved researchers have highlighted these findings and provided more in-depth analyses of processes underlying key carbon fluxes in continental margin systems. As a culminating outcome of these synthesis efforts, a comprehensive science plan highlights key knowledge gaps identified during this synthesis and provides explicit guidance on future research and observing priorities in continental margin systems to help inform future agency investments in continental margins research. This presentation will provide an overview of regional and flux-based (terrestrial inputs, biological transformations, sedimentary processes, atmospheric exchanges, lateral carbon transport) synthesis findings and key recommendations in the science plan, as well as a set of overarching priorities and recommendations on observations and modeling approaches for continental margin systems.

  11. Heat Flux Distribution of Antarctica Unveiled

    Science.gov (United States)

    Martos, Yasmina M.; Catalán, Manuel; Jordan, Tom A.; Golynsky, Alexander; Golynsky, Dmitry; Eagles, Graeme; Vaughan, David G.

    2017-11-01

    Antarctica is the largest reservoir of ice on Earth. Understanding its ice sheet dynamics is crucial to unraveling past global climate change and making robust climatic and sea level predictions. Of the basic parameters that shape and control ice flow, the most poorly known is geothermal heat flux. Direct observations of heat flux are difficult to obtain in Antarctica, and until now continent-wide heat flux maps have only been derived from low-resolution satellite magnetic and seismological data. We present a high-resolution heat flux map and associated uncertainty derived from spectral analysis of the most advanced continental compilation of airborne magnetic data. Small-scale spatial variability and features consistent with known geology are better reproduced than in previous models, between 36% and 50%. Our high-resolution heat flux map and its uncertainty distribution provide an important new boundary condition to be used in studies on future subglacial hydrology, ice sheet dynamics, and sea level change.

  12. Flux Modulation in the Electrodynamic Loudspeaker

    DEFF Research Database (Denmark)

    Halvorsen, Morten; Tinggaard, Carsten; Agerkvist, Finn T.

    2015-01-01

    This paper discusses the effect of flux modulation in the electrodynamic loudspeaker with main focus on the effect on the force factor. A measurement setup to measure the AC flux modulation with static voice coil is explained and the measurements shows good consistency with FEA simulations....... Measurements of the generated AC flux modulation shows, that eddy currents are the main source to magnetic losses in form of phase lag and amplitude changes. Use of a copper cap shows a decrease in flux modulation amplitude at the expense of increased power losses. Finally, simulations show...... that there is a high dependency between the generated AC flux modulation from the voice coil and the AC force factor change....

  13. Spacecraft-produced neutron fluxes on Skylab

    Science.gov (United States)

    Quist, T. C.; Furst, M.; Burnett, D. S.; Baum, J. H.; Peacock, C. L., Jr.; Perry, D. G.

    1977-01-01

    Estimates of neutron fluxes in different energy ranges are reported for the Skylab spacecraft. Detectors composed of uranium, thorium, and bismuth foils with mica as a fission track recorder, as well as boron foils with cellulose acetate as an alpha-particle recorder, were deployed at different positions in the Orbital Workshop. It was found that the Skylab neutron flux was dominated by high energy (greater than 1 MeV) contributions and that there was no significant time variation in the fluxes. Firm upper limits of 7-15 neutrons/sq cm-sec, depending on the detector location in the spacecraft, were established for fluxes above 1 MeV. Below 1 MeV, the neutron fluxes were about an order of magnitude lower. The neutrons are interpreted as originating from the interactions of leakage protons from the radiation belt with the spacecraft.

  14. OpenFLUX: efficient modelling software for 13C-based metabolic flux analysis

    Directory of Open Access Journals (Sweden)

    Nielsen Lars K

    2009-05-01

    Full Text Available Abstract Background The quantitative analysis of metabolic fluxes, i.e., in vivo activities of intracellular enzymes and pathways, provides key information on biological systems in systems biology and metabolic engineering. It is based on a comprehensive approach combining (i tracer cultivation on 13C substrates, (ii 13C labelling analysis by mass spectrometry and (iii mathematical modelling for experimental design, data processing, flux calculation and statistics. Whereas the cultivation and the analytical part is fairly advanced, a lack of appropriate modelling software solutions for all modelling aspects in flux studies is limiting the application of metabolic flux analysis. Results We have developed OpenFLUX as a user friendly, yet flexible software application for small and large scale 13C metabolic flux analysis. The application is based on the new Elementary Metabolite Unit (EMU framework, significantly enhancing computation speed for flux calculation. From simple notation of metabolic reaction networks defined in a spreadsheet, the OpenFLUX parser automatically generates MATLAB-readable metabolite and isotopomer balances, thus strongly facilitating model creation. The model can be used to perform experimental design, parameter estimation and sensitivity analysis either using the built-in gradient-based search or Monte Carlo algorithms or in user-defined algorithms. Exemplified for a microbial flux study with 71 reactions, 8 free flux parameters and mass isotopomer distribution of 10 metabolites, OpenFLUX allowed to automatically compile the EMU-based model from an Excel file containing metabolic reactions and carbon transfer mechanisms, showing it's user-friendliness. It reliably reproduced the published data and optimum flux distributions for the network under study were found quickly ( Conclusion We have developed a fast, accurate application to perform steady-state 13C metabolic flux analysis. OpenFLUX will strongly facilitate and

  15. The development and validation of an unmanned aerial system (UAS) for the measurement of methane flux

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Hatfield, Kirk [Univ. of Florida, Gainesville, FL (United States)

    2015-02-10

    controlled field conditions. In the third and fourth year a suite of larger field studies were conducted. For these studies, the uranium flux sensor was used with uranium speciation measurements and molecular-biological tools to characterize microbial community and active biomass at synonymous wells distributed in a large grid. These field efforts quantified spatial changes in uranium flux and field-scale rates of uranium attenuation (ambient and stimulated), uranium stability, and quantitatively assessed how fluxes and effective reaction rates were coupled to spatial variations in microbial community and active biomass. Analyses of data from these field experiments were used to generate estimates of Monod kinetic parameters that are ‘effective’ in nature and optimal for modeling uranium fate and transport at the field-scale. This project provided the opportunity to develop the first sensor that provides direct measures of both uranium (VI) and groundwater flux. A multidisciplinary team was assembled to include two geochemists, a microbiologist, and two quantitative contaminant hydrologists. Now that the project is complete, the sensor can be deployed at DOE sites to evaluate field-scale uranium attenuation, source behavior, the efficacy of remediation, and off-site risk. Because the sensor requires no power, it can be deployed at remote sites for periods of days to months. The fundamental science derived from this project can be used to advance the development of predictive models for various transport and attenuation processes in aquifers. Proper development of these models is critical for long-term stewardship of contaminated sites in the context of predicting uranium source behavior, remediation performance, and off-site risk.

  17. Primary Science Interview: Science Sparks

    Science.gov (United States)

    Bianchi, Lynne

    2016-01-01

    In this "Primary Science" interview, Lynne Bianchi talks with Emma Vanstone about "Science Sparks," which is a website full of creative, fun, and exciting science activity ideas for children of primary-school age. "Science Sparks" started with the aim of inspiring more parents to do science at home with their…

  18. Neutron flux enhancement in the NRAD reactor

    International Nuclear Information System (INIS)

    Weeks, A.A.; Heidel, C.C.; Imel, G.R.

    1988-01-01

    In 1987 a series of experiments were conducted at the NRAD reactor facility at Argonne National Laboratory - West (ANL-W) to investigate the possibility of increasing the thermal neutron content at the end of the reactor's east beam tube through the use of hydrogenous flux traps. It was desired to increase the thermal flux for a series of experiments to be performed in the east radiography cell, in which the enhanced flux was required in a relatively small volume. Hence, it was feasible to attempt to focus the cross section of the beam to a smaller area. Two flux traps were constructed from unborated polypropylene and tested to determine their effectiveness. Both traps were open to the entire cross-sectional area of the neutron beam (as it emerges from the wall and enters the beam room). The sides then converged such that at the end of the trap the beam would be 'focused' to a greater intensity. The differences in the two flux traps were primarily in length, and hence angle to the beam as the inlet and outlet cross-sectional areas were held constant. The experiments have contributed to the design of a flux trap in which a thermal flux of nearly 10 9 was obtained, with an enhancement of 6.61

  19. CO2 flux geothermometer for geothermal exploration

    Science.gov (United States)

    Harvey, M. C.; Rowland, J. V.; Chiodini, G.; Rissmann, C. F.; Bloomberg, S.; Fridriksson, T.; Oladottir, A. A.

    2017-09-01

    A new geothermometer (TCO2 Flux) is proposed based on soil diffuse CO2 flux and shallow temperature measurements made on areas of steam heated, thermally altered ground above active geothermal systems. This CO2 flux geothermometer is based on a previously reported CO2 geothermometer that was designed for use with fumarole analysis. The new geothermometer provides a valuable additional exploration tool for estimating subsurface temperatures in high-temperature geothermal systems. Mean TCO2 Flux estimates fall within the range of deep drill hole temperatures at Wairakei (New Zealand), Tauhara (New Zealand), Rotokawa (New Zealand), Ohaaki (New Zealand), Reykjanes (Iceland) and Copahue (Argentina). The spatial distribution of geothermometry estimates is consistent with the location of major upflow zones previously reported at the Wairakei and Rotokawa geothermal systems. TCO2 Flux was also evaluated at White Island (New Zealand) and Reporoa (New Zealand), where limited sub-surface data exists. Mode TCO2 Flux at White Island is high (320 °C), the highest of the systems considered in this study. However, the geothermometer relies on mineral-water equilibrium in neutral pH reservoir fluids, and would not be reliable in such an active and acidic environment. Mean TCO2 Flux at Reporoa (310 °C) is high, which indicates Reporoa has a separate upflow from the nearby Waiotapu geothermal system; an outflow from Waiotapu would not be expected to have such high temperature.

  20. Communicating Science

    Science.gov (United States)

    Russell, Nicholas

    2009-10-01

    Introduction: what this book is about and why you might want to read it; Prologue: three orphans share a common paternity: professional science communication, popular journalism, and literary fiction are not as separate as they seem; Part I. Professional Science Communication: 1. Spreading the word: the endless struggle to publish professional science; 2. Walk like an Egyptian: the alien feeling of professional science writing; 3. The future's bright? Professional science communication in the age of the internet; 4. Counting the horse's teeth: professional standards in science's barter economy; 5. Separating the wheat from the chaff: peer review on trial; Part II. Science for the Public: What Science Do People Need and How Might They Get It?: 6. The Public Understanding of Science (PUS) movement and its problems; 7. Public engagement with science and technology (PEST): fine principle, difficult practice; 8. Citizen scientists? Democratic input into science policy; 9. Teaching and learning science in schools: implications for popular science communication; Part III. Popular Science Communication: The Press and Broadcasting: 10. What every scientist should know about mass media; 11. What every scientist should know about journalists; 12. The influence of new media; 13. How the media represents science; 14. How should science journalists behave?; Part IV. The Origins of Science in Cultural Context: Five Historic Dramas: 15. A terrible storm in Wittenberg: natural knowledge through sorcery and evil; 16. A terrible storm in the Mediterranean: controlling nature with white magic and religion; 17. Thieving magpies: the subtle art of false projecting; 18. Foolish virtuosi: natural philosophy emerges as a distinct discipline but many cannot take it seriously; 19. Is scientific knowledge 'true' or should it just be 'truthfully' deployed?; Part V. Science in Literature: 20. Science and the Gothic: the three big nineteenth-century monster stories; 21. Science fiction: serious

  1. Eddy Correlation Flux Measurement System (ECOR) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Magnetic refrigeration using flux compression in superconductors

    International Nuclear Information System (INIS)

    Israelsson, U.E.; Strayer, D.M.; Jackson, H.W.; Petrac, D.

    1990-01-01

    The feasibility of using flux compression in high-temperature superconductors to produce the large time-varying magnetic fields required in a field cycled magnetic refrigerator operating between 20 K and 4 K is presently investigated. This paper describes the refrigerator concept and lists limitations and advantages in comparison with conventional refrigeration techniques. The maximum fields obtainable by flux compression in high-temperature superconductor materials, as presently prepared, are too low to serve in such a refrigerator. However, reports exist of critical current values that are near usable levels for flux pumps in refrigerator applications. 9 refs

  3. Magnetospheric Multiscale Mission Observations of Magnetic Flux Ropes in the Earth's Plasma Sheet

    Science.gov (United States)

    Slavin, J. A.; Akhavan-Tafti, M.; Poh, G.; Le, G.; Russell, C. T.; Nakamura, R.; Baumjohann, W.; Torbert, R. B.; Gershman, D. J.; Pollock, C. J.; Giles, B. L.; Moore, T. E.; Burch, J. L.

    2017-12-01

    A major discovery by the Cluster mission and the previous generation of science missions is the presence of earthward and tailward moving magnetic flux ropes in the Earth's plasma sheet. However, the lack of high-time resolution plasma measurements severely limited progress concerning the formation and evolution of these reconnection generated structures. We use high-time resolution magnetic and electric field and plasma measurements from the Magnetospheric Multiscale mission's first tail season to investigate: 1) the distribution of flux rope diameters relative to the local ion and electron inertial lengths; 2) the internal force balance sustaining these structures; and 3) the magnetic connectivity of the flux ropes to the Earth and/or the interplanetary medium; 4) the specific entropy of earthward moving flux ropes and the possible effect of "buoyancy" on how deep they penetrate into the inner magnetosphere; and 5) evidence for coalescence of adjacent flux ropes and/or the division of existing flux ropes through the formation of secondary X-lines. The results of these initial analyses will be discussed in terms of their implications for reconnection-driven magnetospheric dynamics and substorms.

  4. Neutron activation analysis: Modelling studies to improve the neutron flux of Americium Beryllium source

    OpenAIRE

    Didi, Abdessamad; Dadouch, A.; Jaï, O.; Tajmouati, J.; El Bekkouri, H.

    2017-01-01

    Americium–beryllium (Am-Be; n, γ) is a neutron emitting source used in various research fields such as chemistry, physics, geology, archaeology, medicine, and environmental monitoring, as well as in the forensic sciences. It is a mobile source of neutron activity (20 Ci), yielding a small thermal neutron flux that is water moderated. The aim of this study is to develop a model to increase the neutron thermal flux of a source such as Am-Be. This study achieved multiple advantageous results: pr...

  5. Evolution of magnetic flux ropes associated with flux transfer events and interplanetary magnetic clouds

    International Nuclear Information System (INIS)

    Wei, C.Q.; Lee, L.C.; Wang, S.; Akasofu, S.I.

    1991-01-01

    Spacecraft observations suggest that flux transfer events and interplanetary magnetic clouds may be associated with magnetic flux ropes which are magnetic flux tubes containing helical magnetic field lines. In the magnetic flux ropes, the azimuthal magnetic field (B θ ) is superposed on the axial field (B z ). In this paper the time evolution of a localized magnetic flux rope is studied. A two-dimensional compressible magnetohydrodynamic simulation code with a cylindrical symmetry is developed to study the wave modes associated with the evolution of flux ropes. It is found that in the initial phase both the fast magnetosonic wave and the Alfven wave are developed in the flux rope. After this initial phase, the Alfven wave becomes the dominant wave mode for the evolution of the magnetic flux rope and the radial expansion velocity of the flux rope is found to be negligible. Numerical results further show that even for a large initial azimuthal component of the magnetic field (B θ ≅ 1-4 B z ) the propagation velocity along the axial direction of the flux rope remains to be the Alfven velocity. Diagnoses show that after the initial phase the transverse kinetic energy equals the transverse magnetic energy, which is characteristic of the Alfven mode. It is also found that the localized magnetic flux rope tends to evolve into two separate magnetic ropes propagating in opposite directions. The simulation results are used to study the evolution of magnetic flux ropes associated with flux transfer events observed at the Earth's dayside magnetopause and magnetic clouds in the interplanetary space

  6. Accuracy of surface heat fluxes from observations of operational satellites

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Sugimori, Y.

    Uncertainties in the flux estimates, resulting from the use of bulk method and remotely sensed data are worked out and are presented for individual and total fluxes. These uncertainties in satellite derived fluxes are further compared...

  7. A practical CO2 flux remote sensing technique

    Science.gov (United States)

    Queisser, Manuel; Burton, Mike

    2017-04-01

    An accurate quantification of CO2 flux from both natural and anthropogenic sources is of great interest in various areas of the Earth, environmental and atmospheric sciences. As emitted excess CO2 quickly dilutes into the 400 ppm ambient CO2 concentration and degassing often occurs diffusively, measuring CO2 fluxes is challenging. Therefore, fluxes are usually derived from grids of in-situ measurements, which are labour intensive measurements. Other than a safe measurement distance, remote sensing offers quick, spatially integrated and thus a more thorough measurement of gas fluxes. Active remote sensing combines these merits with operation independent of sunlight or clear sky conditions. Due to their weight and size, active remote sensing platforms for CO2, such as LIDAR, cannot easily be applied in the field or transported overseas. Moreover, their complexity requires a rather lengthy setup procedure to be undertaken by skilled personal. To meet the need for a rugged, practical CO2 remote sensing technique to scan volcanic plumes, we have developed the CO2 LIDAR. It measures 1-D column densities of CO2 with sufficient sensitivity to reveal the contribution of magmatic CO2. The CO2 LIDAR has been mounted inside a small aircraft and used to measure atmospheric column CO2 concentrations between the aircraft and the ground. It was further employed on the ground, measuring CO2 emissions from mud volcanism. During the measurement campaign the CO2 LIDAR demonstrated reliability, portability, quick set-up time (10 to 15 min) and platform independence. This new technique opens the possibility of rapid, comprehensive surveys of point source, open-vent CO2 emissions, as well as emissions from more diffuse sources such as lakes and fumarole fields. Currently, within the proof-of-concept ERC project CarbSens, a further reduction in size, weight and operational complexity is underway with the goal to commercialize the platform. Areas of potential applications include fugitive

  8. Tetrakis-amido high flux membranes

    Science.gov (United States)

    McCray, S.B.

    1989-10-24

    Composite RO membranes of a microporous polymeric support and a polyamide reaction product of a tetrakis-aminomethyl compound and a polyacylhalide are disclosed, said membranes exhibiting high flux and good chlorine resistance.

  9. 400 Area/Fast Flux Test Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The 400 Area at Hanford is home primarily to the Fast Flux Test Facility (FFTF), a DOE-owned, formerly operating, 400-megawatt (thermal) liquid-metal (sodium)-cooled...

  10. Pulse power applications of flux compression generators

    International Nuclear Information System (INIS)

    Fowler, C.M.; Caird, R.S.; Erickson, D.J.; Freeman, B.L.

    1981-01-01

    Characteristics are presented for two different types of explosive driven flux compression generators and a megavolt pulse transformer. Status reports are given for rail gun and plasma focus programs for which the generators serve as power sources

  11. Rotating flux compressor for energy conversion

    International Nuclear Information System (INIS)

    Chowdhuri, P.; Linton, T.W.; Phillips, J.A.

    1983-01-01

    The rotating flux compressor (RFC) converts rotational kinetic energy into an electrical output pulse which would have higher energy than the electrical energy initially stored in the compressor. An RFC has been designed in which wedge-shaped rotor blades pass through the air gaps between successive turns of a solenoid, the stator. Magnetic flux is generated by pulsing the stator solenoids when the inductance is a maximum, i.e., when the flux fills the stator-solenoid volume. Connecting the solenoid across a load conserves the flux which is compressed within the small volume surrounding the stator periphery when the rotor blades cut into the free space between the stator plates, creating a minimum-inductance condition. The unique features of this design are: (1) no electrical connections (brushes) to the rotor; (2) no conventional windings; and (3) no maintenance. The device has been tested up to 5000 rpm of rotor speed

  12. Modelling drug flux through microporated skin.

    Science.gov (United States)

    Rzhevskiy, Alexey S; Guy, Richard H; Anissimov, Yuri G

    2016-11-10

    A simple mathematical equation has been developed to predict drug flux through microporated skin. The theoretical model is based on an approach applied previously to water evaporation through leaf stomata. Pore density, pore radius and drug molecular weight are key model parameters. The predictions of the model were compared with results derived from a simple, intuitive method using porated area alone to estimate the flux enhancement. It is shown that the new approach predicts significantly higher fluxes than the intuitive analysis, with transport being proportional to the total pore perimeter rather than area as intuitively anticipated. Predicted fluxes were in good general agreement with experimental data on drug delivery from the literature, and were quantitatively closer to the measured values than those derived from the intuitive, area-based approach. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Flux Tube Dynamics in the Dual Superconductor

    International Nuclear Information System (INIS)

    Lampert, M.; Svetitsky, B.

    1999-01-01

    We have studied plasma oscillations in a flux tube created in a dual superconductor. The theory contains an Abelian gauge field coupled magnetically to a Higgs field that confines electric charge via the dual Meissner effect. Starting from a static flux tube configuration, with electric charges at either end, we release a fluid of electric charges in the system that accelerate and screen the electric field. The weakening of the electric field allows the flux tube to collapse, and the inertia of the charges forces it open again. We investigate both Type I and Type II superconductors, with plasma frequencies both above and below the threshold for radiation into the Higgs vacuum. (The parameters appropriate to QCD are in the Type II regime; the plasma frequency depends on the mass taken for the fluid constituents.) The coupling of the plasma oscillations to the Higgs field making up the flux tube is the main new feature in our work

  14. CO2 fluxes near a forest edge

    DEFF Research Database (Denmark)

    Sogachev, Andrey; Leclerc, Monique Y.; Zhang, Gensheng

    2008-01-01

    the concentration and flux fields against those of a uniform forested surface. We use an atmospheric boundary layer two-equation closure model that accounts for the flow dynamics and vertical divergence of CO2 sources/sinks within a plant canopy. This paper characterizes the spatial variation of CO2 fluxes...... as a function of both sources/sinks distribution and the vertical structure of the canopy. Results suggest that the ground source plays a major role in the formation of wave-like vertical CO2 flux behavior downwind of a forest edge, despite the fact that the contribution of foliage sources/sinks changes...... monotonously. Such a variation is caused by scalar advection in the trunk space and reveals itself as a decrease or increase in vertical fluxes over the forest relative to carbon dioxide exchange of the underlying forest. The effect was more pronounced in model forests where the leaf area is concentrated...

  15. Food Science.

    Science.gov (United States)

    Barkman, Susan J.

    1996-01-01

    Presents food science experiments designed for high school science classes that aim at getting students excited about science and providing them with real-life applications. Enables students to see the application of chemistry, microbiology, engineering, and other basic and applied sciences to the production, processing, preservation, evaluation,…

  16. Science/s.

    Directory of Open Access Journals (Sweden)

    Emmanuelle Tricoire

    2005-03-01

    Full Text Available Un forum a été organisé en mars par la Commission européenne. Il s’appelait « Science in Society ». Depuis 2000 la Commission a mis en place un Plan d’Action élaboré pour que soit promue « la science » au sein du public, afin que les citoyens prennent de bonnes décisions, des décisions informées. Il s’agit donc de développer la réflexivité au sein de la société, pour que cette dernière agisse avec discernement dans un monde qu’elle travaille à rendre durable. ...

  17. Magnetic flux generator for balanced membrane loudspeaker

    DEFF Research Database (Denmark)

    Rehder, Jörg; Rombach, Pirmin; Hansen, Ole

    2002-01-01

    This paper reports the development of a magnetic flux generator with an application in a hearing aid loudspeaker produced in microsystem technology (MST). The technology plans for two different designs for the magnetic flux generator utilizing a softmagnetic substrate or electroplated NiCoFe as c......CoFe as core material are presented and the production and characterization of four different mono- and double-layer planar coil types are reported....

  18. Stochastic flux analysis of chemical reaction networks.

    Science.gov (United States)

    Kahramanoğulları, Ozan; Lynch, James F

    2013-12-07

    Chemical reaction networks provide an abstraction scheme for a broad range of models in biology and ecology. The two common means for simulating these networks are the deterministic and the stochastic approaches. The traditional deterministic approach, based on differential equations, enjoys a rich set of analysis techniques, including a treatment of reaction fluxes. However, the discrete stochastic simulations, which provide advantages in some cases, lack a quantitative treatment of network fluxes. We describe a method for flux analysis of chemical reaction networks, where flux is given by the flow of species between reactions in stochastic simulations of the network. Extending discrete event simulation algorithms, our method constructs several data structures, and thereby reveals a variety of statistics about resource creation and consumption during the simulation. We use these structures to quantify the causal interdependence and relative importance of the reactions at arbitrary time intervals with respect to the network fluxes. This allows us to construct reduced networks that have the same flux-behavior, and compare these networks, also with respect to their time series. We demonstrate our approach on an extended example based on a published ODE model of the same network, that is, Rho GTP-binding proteins, and on other models from biology and ecology. We provide a fully stochastic treatment of flux analysis. As in deterministic analysis, our method delivers the network behavior in terms of species transformations. Moreover, our stochastic analysis can be applied, not only at steady state, but at arbitrary time intervals, and used to identify the flow of specific species between specific reactions. Our cases study of Rho GTP-binding proteins reveals the role played by the cyclic reverse fluxes in tuning the behavior of this network.

  19. Determination flux in the Reactor JEN-1

    International Nuclear Information System (INIS)

    Manas Diaz, L.; Montes Ponce de leon, J.

    1960-01-01

    This report summarized several irradiations that have been made to determine the neutron flux distributions in the core of the JEN-1 reactor. Gold foils of 380 μ gr and Mn-Ni (12% de Ni) of 30 mg have been employed. the epithermal flux has been determined by mean of the Cd radio. The resonance integral values given by Macklin and Pomerance have been used. (Author) 9 refs

  20. Flux at a point in MCNP

    International Nuclear Information System (INIS)

    Cashwell, E.D.; Schrandt, R.G.

    1980-01-01

    The current state of the art of calculating flux at a point with MCNP is discussed. Various techniques are touched upon, but the main emphasis is on the fast improved version of the once-more-collided flux estimator, which has been modified to treat neutrons thermalized by the free gas model. The method is tested on several problems on interest and the results are presented

  1. Controlling fluxes for microbial metabolic engineering

    OpenAIRE

    Sachdeva, Gairik

    2014-01-01

    This thesis presents novel synthetic biology tools and design principles usable for microbial metabolic engineering. Controlling metabolic fluxes is essential for biological manufacturing of fuels, materials, and high value chemicals. Insulating the flow of metabolites is a successful natural strategy for metabolic flux regulation. Recently, approaches using scaffolds, both in vitro and in vivo, to spatially co-localize enzymes have reported significant gains in product yields. RNA is suitabl...

  2. Mold Flux Crystallization and Mold Thermal Behavior

    Science.gov (United States)

    Peterson, Elizabeth Irene

    Mold flux plays a small but critical role in the continuous casting of steel. The carbon-coated powder is added at the top of the water-cooled copper mold, over time it melts and infiltrates the gap between the copper mold and the solidifying steel strand. Mold powders serve five primary functions: (1) chemical insulation, (2) thermal insulation, (3) lubrication between the steel strand and mold, (4) absorption of inclusions, and (5) promotion of even heat flux. All five functions are critical to slab casting, but surface defect prevention is primarily controlled through even heat flux. Glassy fluxes have high heat transfer and result in a thicker steel shell. Steels with large volumetric shrinkage on cooling must have a crystalline flux to reduce the radiative heat transfer and avoid the formation of cracks in the shell. Crystallinity plays a critical role in steel shell formation, therefore it is important to study the thermal conditions that promote each phase and its morphology. Laboratory tests were performed to generate continuous cooling transformation (CCT) and time-temperature-transformation (TTT) diagrams. Continuous cooling transformation tests were performed in an instrumented eight cell step chill mold. Results showed that cuspidine was the only phase formed in conventional fluxes and all observed structures were dendritic. An isothermal tin bath quench method was also developed to isothermally age glassy samples. Isothermal tests yielded different microstructures and different phases than those observed by continuous cooling. Comparison of aged tests with industrial flux films indicates similar faceted structures along the mold wall, suggesting that mold flux first solidifies as a glass along the mold wall, but the elevated temperature devitrifies the glassy structure forming crystals that cannot form by continuous cooling.

  3. Bidirectional solar wind electron heat flux events

    International Nuclear Information System (INIS)

    Gosling, J.T.; Baker, D.N.; Bame, S.J.; Feldman, W.C.; Zwickl, R.D.; Smith, E.J.

    1987-01-01

    Normally the approx. >80-eV electrons which carry the solar wind electron heat flux are collimated along the interplanetary magnetic field (IMF) in the direction pointing outward away from the sun. Occasionally, however, collimated fluxes of approx. >80-eV electrons are observed traveling both parallel and antiparallel to the IMF. Here we present the results of a survey of such bidirectional electron heat flux events as observed with the plasma and magnetic field experiments aboard ISEE 3 at times when the spacecraft was not magnetically connected to the earth's bow shock. The onset of a bidirectional electron heat flux at ISEE 3 usually signals spacecraft entry into a distinct solar wind plasma and field entity, most often characterized by anomalously low proton and electron temperatures, a strong, smoothly varying magnetic field, a low plasma beta, and a high total pressure. Significant field rotations often occur at the beginning and/or end of bidirectional heat flux events, and, at times, the large field rotations characteristic of ''magnetic clouds'' are present. Approximately half of all bidirectional heat flux events are associated with and follow interplanetary shocks, while the other events have no obvious shock associations

  4. Turbulent fluxes by "Conditional Eddy Sampling"

    Science.gov (United States)

    Siebicke, Lukas

    2015-04-01

    Turbulent flux measurements are key to understanding ecosystem scale energy and matter exchange, including atmospheric trace gases. While the eddy covariance approach has evolved as an invaluable tool to quantify fluxes of e.g. CO2 and H2O continuously, it is limited to very few atmospheric constituents for which sufficiently fast analyzers exist. High instrument cost, lack of field-readiness or high power consumption (e.g. many recent laser-based systems requiring strong vacuum) further impair application to other tracers. Alternative micrometeorological approaches such as conditional sampling might overcome major limitations. Although the idea of eddy accumulation has already been proposed by Desjardin in 1972 (Desjardin, 1977), at the time it could not be realized for trace gases. Major simplifications by Businger and Oncley (1990) lead to it's widespread application as 'Relaxed Eddy Accumulation' (REA). However, those simplifications (flux gradient similarity with constant flow rate sampling irrespective of vertical wind velocity and introduction of a deadband around zero vertical wind velocity) have degraded eddy accumulation to an indirect method, introducing issues of scalar similarity and often lack of suitable scalar flux proxies. Here we present a real implementation of a true eddy accumulation system according to the original concept. Key to our approach, which we call 'Conditional Eddy Sampling' (CES), is the mathematical formulation of conditional sampling in it's true form of a direct eddy flux measurement paired with a performant real implementation. Dedicated hardware controlled by near-real-time software allows full signal recovery at 10 or 20 Hz, very fast valve switching, instant vertical wind velocity proportional flow rate control, virtually no deadband and adaptive power management. Demonstrated system performance often exceeds requirements for flux measurements by orders of magnitude. The system's exceptionally low power consumption is ideal

  5. Science Fiction and Science Education.

    Science.gov (United States)

    Cavanaugh, Terence

    2002-01-01

    Uses science fiction films such as "Jurassic Park" or "Anaconda" to teach science concepts while fostering student interest. Advocates science fiction as a teaching tool to improve learning and motivation. Describes how to use science fiction in the classroom with the sample activity Twister. (YDS)

  6. A finite element calculation of flux pumping

    Science.gov (United States)

    Campbell, A. M.

    2017-12-01

    A flux pump is not only a fascinating example of the power of Faraday’s concept of flux lines, but also an attractive way of powering superconducting magnets without large electronic power supplies. However it is not possible to do this in HTS by driving a part of the superconductor normal, it must be done by exceeding the local critical density. The picture of a magnet pulling flux lines through the material is attractive, but as there is no direct contact between flux lines in the magnet and vortices, unless the gap between them is comparable to the coherence length, the process must be explicable in terms of classical electromagnetism and a nonlinear V-I characteristic. In this paper a simple 2D model of a flux pump is used to determine the pumping behaviour from first principles and the geometry. It is analysed with finite element software using the A formulation and FlexPDE. A thin magnet is passed across one or more superconductors connected to a load, which is a large rectangular loop. This means that the self and mutual inductances can be calculated explicitly. A wide strip, a narrow strip and two conductors are considered. Also an analytic circuit model is analysed. In all cases the critical state model is used, so the flux flow resistivity and dynamic resistivity are not directly involved, although an effective resistivity appears when J c is exceeded. In most of the cases considered here is a large gap between the theory and the experiments. In particular the maximum flux transferred to the load area is always less than the flux of the magnet. Also once the threshold needed for pumping is exceeded the flux in the load saturates within a few cycles. However the analytic circuit model allows a simple modification to allow for the large reduction in I c when the magnet is over a conductor. This not only changes the direction of the pumped flux but leads to much more effective pumping.

  7. Estimating surface fluxes using eddy covariance and numerical ogive optimization

    DEFF Research Database (Denmark)

    Sievers, J.; Papakyriakou, T.; Larsen, Søren Ejling

    2015-01-01

    Estimating representative surface fluxes using eddy covariance leads invariably to questions concerning inclusion or exclusion of low-frequency flux contributions. For studies where fluxes are linked to local physical parameters and up-scaled through numerical modelling efforts, low......-frequency contributions interfere with our ability to isolate local biogeochemical processes of interest, as represented by turbulent fluxes. No method currently exists to disentangle low-frequency contributions on flux estimates. Here, we present a novel comprehensive numerical scheme to identify and separate out low......-frequency contributions to vertical turbulent surface fluxes. For high flux rates (|Sensible heat flux| > 40Wm-2, |latent heat flux|> 20Wm-2 and |CO2 flux|> 100 mmolm-2 d-1/ we found that the average relative difference between fluxes estimated by ogive optimization and the conventional method was low (5–20 %) suggesting...

  8. A model for heliospheric flux-ropes

    Science.gov (United States)

    Nieves-Chinchilla, T.; Linton, M.; Vourlidas, A.; Hidalgo, M. A. U.

    2017-12-01

    This work is presents an analytical flux-rope model, which explores different levels of complexity starting from a circular-cylindrical geometry. The framework of this series of models was established by Nieves-Chinchilla et al. 2016 with the circular-cylindrical analytical flux rope model. The model attempts to describe the magnetic flux rope topology with distorted cross-section as a possible consequence of the interaction with the solar wind. In this model, the flux rope is completely described in a non-orthogonal geometry. The Maxwell equations are solved using tensor calculus consistent with the geometry chosen, invariance along the axial direction, and with the assumption of no radial current density. The model is generalized in terms of the radial and azimuthal dependence of the poloidal current density component and axial current density component. The misalignment between current density and magnetic field is studied in detail for several example profiles of the axial and poloidal current density components. This theoretical analysis provides a map of the force distribution inside of the flux-rope. For reconstruction of the heliospheric flux-ropes, the circular-cylindrical reconstruction technique has been adapted to the new geometry and applied to in situ ICMEs with a flux-rope entrained and tested with cases with clear in situ signatures of distortion. The model adds a piece in the puzzle of the physical-analytical representation of these magnetic structures that should be evaluated with the ultimate goal of reconciling in-situ reconstructions with imaging 3D remote sensing CME reconstructions. Other effects such as axial curvature and/or expansion could be incorporated in the future to fully understand the magnetic structure.

  9. Production flux of sea spray aerosol

    Energy Technology Data Exchange (ETDEWEB)

    de Leeuw, G.; Lewis, E.; Andreas, E. L.; Anguelova, M. D.; Fairall, C. W.; O’Dowd, C.; Schulz, M.; Schwartz, S. E.

    2011-05-07

    Knowledge of the size- and composition-dependent production flux of primary sea spray aerosol (SSA) particles and its dependence on environmental variables is required for modeling cloud microphysical properties and aerosol radiative influences, interpreting measurements of particulate matter in coastal areas and its relation to air quality, and evaluating rates of uptake and reactions of gases in sea spray drops. This review examines recent research pertinent to SSA production flux, which deals mainly with production of particles with r{sub 80} (equilibrium radius at 80% relative humidity) less than 1 {micro}m and as small as 0.01 {micro}m. Production of sea spray particles and its dependence on controlling factors has been investigated in laboratory studies that have examined the dependences on water temperature, salinity, and the presence of organics and in field measurements with micrometeorological techniques that use newly developed fast optical particle sizers. Extensive measurements show that water-insoluble organic matter contributes substantially to the composition of SSA particles with r{sub 80} < 0.25 {micro}m and, in locations with high biological activity, can be the dominant constituent. Order-of-magnitude variation remains in estimates of the size-dependent production flux per white area, the quantity central to formulations of the production flux based on the whitecap method. This variation indicates that the production flux may depend on quantities such as the volume flux of air bubbles to the surface that are not accounted for in current models. Variation in estimates of the whitecap fraction as a function of wind speed contributes additional, comparable uncertainty to production flux estimates.

  10. Derivative processes for modelling metabolic fluxes

    Science.gov (United States)

    Žurauskienė, Justina; Kirk, Paul; Thorne, Thomas; Pinney, John; Stumpf, Michael

    2014-01-01

    Motivation: One of the challenging questions in modelling biological systems is to characterize the functional forms of the processes that control and orchestrate molecular and cellular phenotypes. Recently proposed methods for the analysis of metabolic pathways, for example, dynamic flux estimation, can only provide estimates of the underlying fluxes at discrete time points but fail to capture the complete temporal behaviour. To describe the dynamic variation of the fluxes, we additionally require the assumption of specific functional forms that can capture the temporal behaviour. However, it also remains unclear how to address the noise which might be present in experimentally measured metabolite concentrations. Results: Here we propose a novel approach to modelling metabolic fluxes: derivative processes that are based on multiple-output Gaussian processes (MGPs), which are a flexible non-parametric Bayesian modelling technique. The main advantages that follow from MGPs approach include the natural non-parametric representation of the fluxes and ability to impute the missing data in between the measurements. Our derivative process approach allows us to model changes in metabolite derivative concentrations and to characterize the temporal behaviour of metabolic fluxes from time course data. Because the derivative of a Gaussian process is itself a Gaussian process, we can readily link metabolite concentrations to metabolic fluxes and vice versa. Here we discuss how this can be implemented in an MGP framework and illustrate its application to simple models, including nitrogen metabolism in Escherichia coli. Availability and implementation: R code is available from the authors upon request. Contact: j.norkunaite@imperial.ac.uk; m.stumpf@imperial.ac.uk Supplementary information: Supplementary data are available at Bioinformatics online. PMID:24578401

  11. Neutron activation analysis: Modelling studies to improve the neutron flux of Americium-Beryllium source

    Energy Technology Data Exchange (ETDEWEB)

    Didi, Abdessamad; Dadouch, Ahmed; Tajmouati, Jaouad; Bekkouri, Hassane [Advanced Technology and Integration System, Dept. of Physics, Faculty of Science Dhar Mehraz, University Sidi Mohamed Ben Abdellah, Fez (Morocco); Jai, Otman [Laboratory of Radiation and Nuclear Systems, Dept. of Physics, Faculty of Sciences, Tetouan (Morocco)

    2017-06-15

    Americium–beryllium (Am-Be; n, γ) is a neutron emitting source used in various research fields such as chemistry, physics, geology, archaeology, medicine, and environmental monitoring, as well as in the forensic sciences. It is a mobile source of neutron activity (20 Ci), yielding a small thermal neutron flux that is water moderated. The aim of this study is to develop a model to increase the neutron thermal flux of a source such as Am-Be. This study achieved multiple advantageous results: primarily, it will help us perform neutron activation analysis. Next, it will give us the opportunity to produce radio-elements with short half-lives. Am-Be single and multisource (5 sources) experiments were performed within an irradiation facility with a paraffin moderator. The resulting models mainly increase the thermal neutron flux compared to the traditional method with water moderator.

  12. Quantifying Sources and Sinks of Reactive Gases in the Lower Atmosphere Using Airborne Flux Observations

    Science.gov (United States)

    Wolfe, G. M.; Hanisco, T. F.; Arkinson, H. L.; Bui, T. P.; Crounse, J. D.; Dean-Day, J.; Goldstein, A.; Guenther, A.; Hall, S. R.; Huey, G.; hide

    2015-01-01

    Atmospheric composition is governed by the interplay of emissions, chemistry, deposition, and transport. Substantial questions surround each of these processes, especially in forested environments with strong biogenic emissions. Utilizing aircraft observations acquired over a forest in the southeast U.S., we calculate eddy covariance fluxes for a suite of reactive gases and apply the synergistic information derived from this analysis to quantify emission and deposition fluxes, oxidant concentrations, aerosol uptake coefficients, and other key parameters. Evaluation of results against state-of-the-science models and parameterizations provides insight into our current understanding of this system and frames future observational priorities. As a near-direct measurement of fundamental process rates, airborne fluxes offer a new tool to improve biogenic and anthropogenic emissions inventories, photochemical mechanisms, and deposition parameterizations.

  13. Turbulent heat flux measurements in thermally stable boundary layers

    Science.gov (United States)

    Williams, Owen J.; van Buren, Tyler; Smits, Alexander J.

    2014-11-01

    Thermally stable turbulent boundary layers are prevalent in the polar regions and nocturnal atmospheric surface layer but heat and momentum flux measurements in such flow are often difficult. Here, a new method is employed using a nanoscale cold-wire (T-NSTAP) adjacent to a 2D PIV light sheet to measure these fluxes within rough-wall turbulent boundary layer. This method combines the advantages of fast thermal frequency response with measurement of the spatial variation of the velocity field. Resolution is limited solely by the separation of the probe and the light sheet. The new technique is used to examine the applicability of Monin-Obukhov similarity over a range of Richardson numbers from weak to strongly stable. In addition, the velocity fields are conditionally averaged subject to strong deviations of temperature above and below the local average in an effort to determine the relationship between the coherent turbulent motions and the fluctuating temperature field. This work was supported by the Princeton University Cooperative Institute for Climate Science.

  14. Measuring Convective Mass Fluxes Over Tropical Oceans

    Science.gov (United States)

    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

  15. Turbulent Fogwater Flux Measurements Above A Forest

    Science.gov (United States)

    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

  16. Flux and brightness calculations for various synchrotron radiation sources

    Energy Technology Data Exchange (ETDEWEB)

    Weber, J.M.; Hulbert, S.L.

    1991-11-01

    Synchrotron radiation (SR) storage rings are powerful scientific and technological tools. The first generation of storage rings in the US., e.g., SURF (Washington, D.C.), Tantalus (Wisconsin), SSRL (Stanford), and CHESS (Cornell), revolutionized VUV, soft X-ray, and hard X-ray science. The second (present) generation of storage rings, e.g. the NSLS VUV and XRAY rings and Aladdin (Wisconsin), have sustained the revolution by providing higher stored currents and up to a factor of ten smaller electron beam sizes than the first generation sources. This has made possible a large number of experiments that could not performed using first generation sources. In addition, the NSLS XRAY ring design optimizes the performance of wigglers (high field periodic magnetic insertion devices). The third generation storage rings, e.g. ALS (Berkeley) and APS (Argonne), are being designed to optimize the performance of undulators (low field periodic magnetic insertion devices). These extremely high brightness sources will further revolutionize x-ray science by providing diffraction-limited x-ray beams. The output of undulators and wigglers is distinct from that of bending magnets in magnitude, spectral shape, and in spatial and angular size. Using published equations, we have developed computer programs to calculate the flux, central intensity, and brightness output bending magnets and selected wigglers and undulators of the NSLS VUV and XRAY rings, the Advanced Light Source (ALS), and the Advanced Photon Source (APS). Following is a summary of the equations used, the graphs and data produced, and the computer codes written. These codes, written in the C programming language, can be used to calculate the flux, central intensity, and brightness curves for bending magnets and insertion devices on any storage ring.

  17. Flux and brightness calculations for various synchrotron radiation sources

    International Nuclear Information System (INIS)

    Weber, J.M.; Hulbert, S.L.

    1991-11-01

    Synchrotron radiation (SR) storage rings are powerful scientific and technological tools. The first generation of storage rings in the US., e.g., SURF (Washington, D.C.), Tantalus (Wisconsin), SSRL (Stanford), and CHESS (Cornell), revolutionized VUV, soft X-ray, and hard X-ray science. The second (present) generation of storage rings, e.g. the NSLS VUV and XRAY rings and Aladdin (Wisconsin), have sustained the revolution by providing higher stored currents and up to a factor of ten smaller electron beam sizes than the first generation sources. This has made possible a large number of experiments that could not performed using first generation sources. In addition, the NSLS XRAY ring design optimizes the performance of wigglers (high field periodic magnetic insertion devices). The third generation storage rings, e.g. ALS (Berkeley) and APS (Argonne), are being designed to optimize the performance of undulators (low field periodic magnetic insertion devices). These extremely high brightness sources will further revolutionize x-ray science by providing diffraction-limited x-ray beams. The output of undulators and wigglers is distinct from that of bending magnets in magnitude, spectral shape, and in spatial and angular size. Using published equations, we have developed computer programs to calculate the flux, central intensity, and brightness output bending magnets and selected wigglers and undulators of the NSLS VUV and XRAY rings, the Advanced Light Source (ALS), and the Advanced Photon Source (APS). Following is a summary of the equations used, the graphs and data produced, and the computer codes written. These codes, written in the C programming language, can be used to calculate the flux, central intensity, and brightness curves for bending magnets and insertion devices on any storage ring

  18. Neutron flux measurement utilizing Campbell technique

    International Nuclear Information System (INIS)

    Kropik, M.

    2000-01-01

    Application of the Campbell technique for the neutron flux measurement is described in the contribution. This technique utilizes the AC component (noise) of a neutron chamber signal rather than a usually used DC component. The Campbell theorem, originally discovered to describe noise behaviour of valves, explains that the root mean square of the AC component of the chamber signal is proportional to the neutron flux (reactor power). The quadratic dependence of the reactor power on the root mean square value usually permits to accomplish the whole current power range of the neutron flux measurement by only one channel. Further advantage of the Campbell technique is that large pulses of the response to neutrons are favoured over small pulses of the response to gamma rays in the ratio of their mean square charge transfer and thus, the Campbell technique provides an excellent gamma rays discrimination in the current operational range of a neutron chamber. The neutron flux measurement channel using state of the art components was designed and put into operation. Its linearity, accuracy, dynamic range, time response and gamma discrimination were tested on the VR-1 nuclear reactor in Prague, and behaviour under high neutron flux (accident conditions) was tested on the TRIGA nuclear reactor in Vienna. (author)

  19. CO2 flux from Javanese mud volcanism

    Science.gov (United States)

    Burton, M. R.; Arzilli, F.; Chiarugi, A.; Marliyani, G. I.; Anggara, F.; Harijoko, A.

    2017-01-01

    Abstract Studying the quantity and origin of CO2 emitted by back‐arc mud volcanoes is critical to correctly model fluid‐dynamical, thermodynamical, and geochemical processes that drive their activity and to constrain their role in the global geochemical carbon cycle. We measured CO2 fluxes of the Bledug Kuwu mud volcano on the Kendeng Fold and thrust belt in the back arc of Central Java, Indonesia, using scanning remote sensing absorption spectroscopy. The data show that the expelled gas is rich in CO2 with a volume fraction of at least 16 vol %. A lower limit CO2 flux of 1.4 kg s−1 (117 t d−1) was determined, in line with the CO2 flux from the Javanese mud volcano LUSI. Extrapolating these results to mud volcanism from the whole of Java suggests an order of magnitude total CO2 flux of 3 kt d−1, comparable with the expected back‐arc efflux of magmatic CO2. After discussing geochemical, geological, and geophysical evidence we conclude that the source of CO2 observed at Bledug Kuwu is likely a mixture of thermogenic, biogenic, and magmatic CO2, with faulting controlling potential pathways for magmatic fluids. This study further demonstrates the merit of man‐portable active remote sensing instruments for probing natural gas releases, enabling bottom‐up quantification of CO2 fluxes. PMID:28944134

  20. CO2 flux from Javanese mud volcanism

    Science.gov (United States)

    Queißer, M.; Burton, M. R.; Arzilli, F.; Chiarugi, A.; Marliyani, G. I.; Anggara, F.; Harijoko, A.

    2017-06-01

    Studying the quantity and origin of CO2 emitted by back-arc mud volcanoes is critical to correctly model fluid-dynamical, thermodynamical, and geochemical processes that drive their activity and to constrain their role in the global geochemical carbon cycle. We measured CO2 fluxes of the Bledug Kuwu mud volcano on the Kendeng Fold and thrust belt in the back arc of Central Java, Indonesia, using scanning remote sensing absorption spectroscopy. The data show that the expelled gas is rich in CO2 with a volume fraction of at least 16 vol %. A lower limit CO2 flux of 1.4 kg s-1 (117 t d-1) was determined, in line with the CO2 flux from the Javanese mud volcano LUSI. Extrapolating these results to mud volcanism from the whole of Java suggests an order of magnitude total CO2 flux of 3 kt d-1, comparable with the expected back-arc efflux of magmatic CO2. After discussing geochemical, geological, and geophysical evidence we conclude that the source of CO2 observed at Bledug Kuwu is likely a mixture of thermogenic, biogenic, and magmatic CO2, with faulting controlling potential pathways for magmatic fluids. This study further demonstrates the merit of man-portable active remote sensing instruments for probing natural gas releases, enabling bottom-up quantification of CO2 fluxes.

  1. Neutron flux enhancement in the NRAD reactor

    International Nuclear Information System (INIS)

    Weeks, A.A.; Heidel, C.C.; Imel, G.R.

    1988-01-01

    In 1987 a series of experiments were conducted at the NRAD reactor facility at Argonne National Laboratory - West (ANL-W) to investigate the possibility of increasing the thermal neutron content at the end of the reactor's east beam tube through the use of hydrogenous flux traps. It was desired to increase the thermal flux for a series of experiments to be performed in the east radiography cell, in which the enhanced flux was required in a relatively small volume. Hence, it was feasible to attempt to focus the cross section of the beam to a smaller area. Two flux traps were constructed from unborated polypropylene and tested to determine their effectiveness. Both traps were open to the entire cross-sectional area of the neutron beam (as it emerges from the wall and enters the beam room). The sides then converged such that at the end of the trap the beam would be 'focused' to a greater intensity. The differences in the two flux traps were primarily in length, and hence angle to the beam as the inlet and outlet cross-sectional areas were held constant. It should be noted that merely placing a slab of polypropylene in the beam will not yield significant multiplication as neutrons are primarily scattered away

  2. The Flux Database Concerted Action (invited paper)

    International Nuclear Information System (INIS)

    Mitchell, N.G.; Donnelly, C.E.

    2000-01-01

    The background to the IUR action on the development of a flux database for radionuclide transfer in soil-plant systems is summarised. The action is discussed in terms of the objectives, the deliverables and the progress achieved by the flux database working group. The paper describes the background to the current initiative, outlines specific features of the database and supporting documentation, and presents findings from the working group's activities. The aim of the IUR flux database working group is to bring together researchers to collate data from current experimental studies investigating aspects of radionuclide transfer in soil-plant systems. The database will incorporate parameters describing the time-dependent transfer of radionuclides between soil, plant and animal compartments. Work under the EC Concerted Action considers soil-plant interactions. This initiative has become known as the radionuclide flux database. It is emphasised that the word flux is used in this case simply to indicate the flow of radionuclides between compartments in time. (author)

  3. About Merging Threshold and Critical Flux Concepts into a Single One: The Boundary Flux

    Directory of Open Access Journals (Sweden)

    Marco Stoller

    2014-01-01

    Full Text Available In the last decades much effort was put in understanding fouling phenomena on membranes. One successful approach to describe fouling issues on membranes is the critical flux theory. The possibility to measure a maximum value of the permeate flux for a given system without incurring in fouling issues was a breakthrough in membrane process design. However, in many cases critical fluxes were found to be very low, lower than the economic feasibility of the process. The knowledge of the critical flux value must be therefore considered as a good starting point for process design. In the last years, a new concept was introduced, the threshold flux, which defines the maximum permeate flow rate characterized by a low constant fouling rate regime. This concept, more than the critical flux, is a new practical tool for membrane process designers. In this paper a brief review on critical and threshold flux will be reported and analyzed. And since the concepts share many common aspects, merged into a new concept, called the boundary flux, the validation will occur by the analysis of previously collected data by the authors, during the treatment of olive vegetation wastewater by ultrafiltration and nanofiltration membranes.

  4. Eddy covariance based methane flux in Sundarbans mangroves, India

    Indian Academy of Sciences (India)

    Eddy covariance based methane flux in Sundarbans mangroves, India ... Eddy covariance; mangrove forests; methane flux; Sundarbans. ... In order to quantify the methane flux in mangroves, an eddy covariance flux tower was recently erected in the largest unpolluted and undisturbed mangrove ecosystem in Sundarbans ...

  5. Fluxes of nitrogen in Chaliyar River Estuary, India

    Digital Repository Service at National Institute of Oceanography (India)

    Xavier, J.K.; Joseph, T.; Paimpillii, J.S.

    the instantaneous nutrient fluxes. The net fluxes are the algebraic sums of the instantaneous fluxes over the tidal cycle sampled divided by the number of observations in the tidal cycle. Net fluxes for all the stations with its cross sectional averages for each...

  6. Generating energy dependent neutron flux maps for effective ...

    African Journals Online (AJOL)

    For activation analysis and irradiation scheme of miniature neutron source reactor, designers or engineers usually require information on thermal neutron flux levels and other energy group flux levels (such as fast, resonance and epithermal). A methodology for readily generating such flux maps and flux profiles for any ...

  7. Non-geometric fluxes and mixed-symmetry potentials

    NARCIS (Netherlands)

    Bergshoeff, E.A.; Penas, V.A.; Riccioni, F.; Risoli, S.

    2015-01-01

    We discuss the relation between generalised fluxes and mixed-symmetry potentials. We refer to the fluxes that cannot be described even locally in the framework of supergravity as ‘non-geometric’. We first consider the NS fluxes, and point out that the non-geometric R flux is dual to a mixed-symmetry

  8. Neutron-diffraction investigations of flux-lines in superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Forgan, E.M. [Birmingham Univ. (United Kingdom); Lee, S.L. [Saint Andrews Univ. (United Kingdom); McKPaul, D. [Warwick Univ., Coventry (United Kingdom); Mook, H.A. [Oak Ridge National Lab., TN (United States); Cubitt, R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    SANS has proved an extremely useful tool for investigating flux-line structures within the bulk of superconductors. With high-T{sub c} materials, the scattered intensities are weak, but careful measurements are giving important new information about flux lattices, flux pinning and flux-lattice melting. (author). 10 refs.

  9. Standardized Automated CO2/H2O Flux Systems for Individual Research Groups and Flux Networks

    Science.gov (United States)

    Burba, George; Begashaw, Israel; Fratini, Gerardo; Griessbaum, Frank; Kathilankal, James; Xu, Liukang; Franz, Daniela; Joseph, Everette; Larmanou, Eric; Miller, Scott; Papale, Dario; Sabbatini, Simone; Sachs, Torsten; Sakai, Ricardo; McDermitt, Dayle

    2017-04-01

    In recent years, spatial and temporal flux data coverage improved significantly, and on multiple scales, from a single station to continental networks, due to standardization, automation, and management of data collection, and better handling of the extensive amounts of generated data. With more stations and networks, larger data flows from each station, and smaller operating budgets, modern tools are required to effectively and efficiently handle the entire process. Such tools are needed to maximize time dedicated to authoring publications and answering research questions, and to minimize time and expenses spent on data acquisition, processing, and quality control. Thus, these tools should produce standardized verifiable datasets and provide a way to cross-share the standardized data with external collaborators to leverage available funding, promote data analyses and publications. LI-COR gas analyzers are widely used in past and present flux networks such as AmeriFlux, ICOS, AsiaFlux, OzFlux, NEON, CarboEurope, and FluxNet-Canada, etc. These analyzers have gone through several major improvements over the past 30 years. However, in 2016, a three-prong development was completed to create an automated flux system which can accept multiple sonic anemometer and datalogger models, compute final and complete fluxes on-site, merge final fluxes with supporting weather soil and radiation data, monitor station outputs and send automated alerts to researchers, and allow secure sharing and cross-sharing of the station and data access. Two types of these research systems were developed: open-path (LI-7500RS) and enclosed-path (LI-7200RS). Key developments included: • Improvement of gas analyzer performance • Standardization and automation of final flux calculations onsite, and in real-time • Seamless integration with latest site management and data sharing tools In terms of the gas analyzer performance, the RS analyzers are based on established LI-7500/A and LI-7200

  10. Icebase: A suborbital survey to map geothermal heat flux under an ice sheet

    Science.gov (United States)

    Purucker, Michael E.; Connerney, John E. P.; Blakely, Richard J.; Bracken, Robert E.; Nowicki, Sophie; Le, Guan; Sabaka, Terence J.; Bonalsky, Todd M.; Kuang, Weijia; Ravat, Dhananjay; Ritz, Catherine; Vaughan, Alan P. M.; Gaina, Carmen; McEnroe, Suzanne; Lesur, Vincent

    2013-04-01

    NASA will solicit suborbital missions as part of its Earth Venture program element in the coming year. These missions are designed as complete PI-led investigations to conduct innovative hypothesis or scientific question-driven approaches to pressing questions in Earth System science. We propose to carry out a suborbital magnetic survey of Greenland using NASA's Global Hawk unmanned aerial vehicle to produce the first-ever map of the geothermal heat flux under an ice sheet. Better constraints on geothermal heat flux will reduce the uncertainty in future sea level rise, in turn allowing a more informed assessment of its impact on society. The geothermal heat flux depends on conditions such as mantle heat flux, and the tectonic history and heat production of the crust, all of which vary spatially. Underneath ice sheets, the geothermal heat flux influences the basal ice. Therefore heat flux is an important boundary condition in ice sheet modeling. Using magnetic data to constrain heat flux is possible because the magnetic properties of rocks are temperature dependent until they reach the Curie temperature. The technique has applications to understanding the response of Greenland ice sheet to climate forcing because the basal heat flux provides one of the boundary conditions. The technique also helps to locate the oldest ice. The oldest ice in Greenland should be found in areas of very low heat flux, and the identification of those areas is provided by this technique. Ice cores from the areas of oldest ice help to decipher past temperatures and CO2 contents. Our latest model of the geothermal heat flux under the Greenland ice sheet (http://websrv.cs.umt.edu/isis/index.php/Greenland_Basal_Heat_Flux) is based on low- resolution satellite observations collected by the CHAMP satellite between 2000 and 2010. Those observations will be enhanced by the upcoming Swarm gradient satellite mission, but the resolution will improve by less than a factor of two, from 400 km

  11. Characterization of ion fluxes and heat fluxes for PMI relevant conditions on Proto-MPEX

    Science.gov (United States)

    Beers, Clyde; Shaw, Guinevere; Biewer, Theodore; Rapp, Juergen

    2016-10-01

    Plasma characterization, in particular, particle flux and electron and ion temperature distributions nearest to an exposed target, are critical to quantifying Plasma Surface Interaction (PSI). In the Proto-Material Plasma Exposure eXperiment (Proto-MPEX), the ion fluxes and heat fluxes are derived from double Langmuir Probes (DLP) and Thomson Scattering in front of the target assuming Bohm conditions at the sheath entrance. Power fluxes derived from ne and Te measurements are compared to heat fluxes measured with IR thermography. The comparison will allow conclusions on the sheath heat transmission coefficient to be made experimentally. Different experimental conditions (low and high density plasmas (0.5 - 6 x 1019 m-3) with different magnetic configuration are compared. This work was supported by the U.S. D.O.E. contract DE-AC05-00OR22725.

  12. Automated flux chamber for investigating gas flux at water-air interfaces.

    Science.gov (United States)

    Duc, Nguyen Thanh; Silverstein, Samuel; Lundmark, Lars; Reyier, Henrik; Crill, Patrick; Bastviken, David

    2013-01-15

    Aquatic ecosystems are major sources of greenhouse gases (GHG). Representative measurements of GHG fluxes from aquatic ecosystems to the atmosphere are vital for quantitative understanding of relationships between biogeochemistry and climate. Fluxes occur at high temporal variability at diel or longer scales, which are not captured by traditional short-term deployments (often in the order of 30 min) of floating flux chambers. High temporal frequency measurements are necessary but also extremely labor intensive if manual flux chamber based methods are used. Therefore, we designed an inexpensive and easily mobile automated flux chamber (AFC) for extended deployments. The AFC was designed to measure in situ accumulation of gas in the chamber and also to collect gas samples in an array of sample bottles for subsequent analysis in the laboratory, providing two independent ways of CH(4) concentration measurements. We here present the AFC design and function together with data from initial laboratory tests and from a field deployment.

  13. Freezing E3-brane instantons with fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, M.; Martucci, L. [Dipartimento di Fisica, Universita di Roma Tor Vergata (Italy); I.N.F.N., Sezione di Roma Tor Vergata (Italy); Collinucci, A. [Theory Group, Physics Department, CERN, Geneva (Switzerland); Physique Theorique et Mathematique Universite Libre de Bruxelles (Belgium)

    2012-07-15

    E3-instantons that generate non-perturbative superpotentials in IIB N = 1 compactifications have a much more frequent occurrence than currently believed. Worldvolume fluxes will typically lift the E3-brane geometric moduli and their fermionic superpartners, leaving only the two required universal fermionic zero-modes. We consistently incorporate SL(2,Z) monodromies and world-volume fluxes in the effective theory of the E3-brane fermions and study the resulting zero modes spectrum, highlighting the relation between F-theory and perturbative IIB results. This leads us to a IIB derivation of the index for generation of superpotential terms, which reproduces and generalizes available results. Furthermore, we show how E3 worldvolume fluxes can be explicitly constructed in a one-modulus compactification, such that the instanton has exactly two fermonic zero-modes. This construction is readily applicable to numerous scenarios. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Heat-Flux Gage thermophosphor system

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, K.W.

    1991-08-01

    This document describes the installation, hardware requirements, and application of the Heat-Flux Gage (Version 1.0) software package developed by the Oak Ridge National Laboratory, Applied Technology Division. The developed software is a single component of a thermographic phosphor-based temperature and heat-flux measurement system. The heat-flux transducer was developed by EG G Energy Measurements Systems and consists of a 1- by 1-in. polymethylpentene sheet coated on the front and back with a repeating thermographic phosphor pattern. The phosphor chosen for this application is gadolinium oxysulphide doped with terbium. This compound has a sensitive temperature response from 10 to 65.6{degree}C (50--150{degree}F) for the 415- and 490-nm spectral emission lines. 3 refs., 17 figs.

  15. Comic ray flux anisotropies caused by astrospheres

    Science.gov (United States)

    Scherer, K.; Strauss, R. D.; Ferreira, S. E. S.; Fichtner, H.

    2016-09-01

    Huge astrospheres or stellar wind bubbles influence the propagation of cosmic rays at energies up to the TeV range and can act as small-scale sinks decreasing the cosmic ray flux. We model such a sink (in 2D) by a sphere of radius 10 pc embedded within a sphere of a radius of 1 kpc. The cosmic ray flux is calculated by means of backward stochastic differential equations from an observer, which is located at r0, to the outer boundary. It turns out that such small-scale sinks can influence the cosmic ray flux at the observer's location by a few permille (i.e. a few 0.1%), which is in the range of the observations by IceCube, Milagro and other large area telescopes.

  16. From Hubble's NGSL to Absolute Fluxes

    Science.gov (United States)

    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.

  17. The FLUKA atmospheric neutrino flux calculation

    CERN Document Server

    Battistoni, G.; Montaruli, T.; Sala, P.R.

    2003-01-01

    The 3-dimensional (3-D) calculation of the atmospheric neutrino flux by means of the FLUKA Monte Carlo model is here described in all details, starting from the latest data on primary cosmic ray spectra. The importance of a 3-D calculation and of its consequences have been already debated in a previous paper. Here instead the focus is on the absolute flux. We stress the relevant aspects of the hadronic interaction model of FLUKA in the atmospheric neutrino flux calculation. This model is constructed and maintained so to provide a high degree of accuracy in the description of particle production. The accuracy achieved in the comparison with data from accelerators and cross checked with data on particle production in atmosphere certifies the reliability of shower calculation in atmosphere. The results presented here can be already used for analysis by current experiments on atmospheric neutrinos. However they represent an intermediate step towards a final release, since this calculation does not yet include the...

  18. MHD energy fluxes for late type dwarfs

    Science.gov (United States)

    Rosner, R.; Musielak, Z. E.

    1987-01-01

    The efficiency of MHD wave generation by turbulent motions in stratified stellar atmospheres with embedded uniform magnetic fields is calculated. In contradiction with previous results, it is shown that there is no significant increase in the efficiency of wave generation because of the presence of magnetic fields, at least within the theory's limits of applicability. It is shown that MHD energy fluxes for late-type stars are less than those obtained for acoustic waves in a magnetic-field-free atmosphere, and do not vary enough for a given spectral type in order to explain observed UV and X-ray fluxes. Thus, the results show that MHD energy fluxes obtained if stellar surface magnetic fields are uniform cannot explain the observed stellar coronal emissions.

  19. Color magnetic flux tubes in dense QCD

    International Nuclear Information System (INIS)

    Eto, Minoru; Nitta, Muneto

    2009-01-01

    QCD is expected to be in the color-flavor locking phase in high baryon density, which exhibits color superconductivity. The most fundamental topological objects in the color superconductor are non-Abelian vortices which are topologically stable color magnetic flux tubes. We present numerical solutions of the color magnetic flux tube for diverse choices of the coupling constants based on the Ginzburg-Landau Lagrangian. We also analytically study its asymptotic profiles and find that they are different from the case of usual superconductors. We propose the width of color magnetic fluxes and find that it is larger than naive expectation of the Compton wavelength of the massive gluon when the gluon mass is larger than the scalar mass.

  20. Real Time Flux Control in PM Motors

    Energy Technology Data Exchange (ETDEWEB)

    Otaduy, P.J.

    2005-09-27

    Significant research at the Oak Ridge National Laboratory (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) is being conducted to develop ways to increase (1) torque, (2) speed range, and (3) efficiency of traction electric motors for hybrid electric vehicles (HEV) within existing current and voltage bounds. Current is limited by the inverter semiconductor devices' capability and voltage is limited by the stator wire insulation's ability to withstand the maximum back-electromotive force (emf), which occurs at the upper end of the speed range. One research track has been to explore ways to control the path and magnitude of magnetic flux while the motor is operating. The phrase, real time flux control (RTFC), refers to this mode of operation in which system parameters are changed while the motor is operating to improve its performance and speed range. RTFC has potential to meet an increased torque demand by introducing additional flux through the main air gap from an external source. It can augment the speed range by diverting flux away from the main air gap to reduce back-emf at high speeds. Conventional RTFC technology is known as vector control [1]. Vector control decomposes the stator current into two components; one that produces torque and a second that opposes (weakens) the magnetic field generated by the rotor, thereby requiring more overall stator current and reducing the efficiency. Efficiency can be improved by selecting a RTFC method that reduces the back-emf without increasing the average current. This favors methods that use pulse currents or very low currents to achieve field weakening. Foremost in ORNL's effort to develop flux control is the work of J. S. Hsu. Early research [2,3] introduced direct control of air-gap flux in permanent magnet (PM) machines and demonstrated it with a flux-controlled generator. The configuration eliminates the problem of demagnetization because it diverts all the flux from the

  1. Open string wavefunctions in flux compactifications

    CERN Document Server

    Cámara, Pablo G

    2009-01-01

    We consider compactifications of type I supergravity on manifolds with SU(3) structure, in the presence of RR fluxes and magnetized D9-branes, and analyze the generalized Dirac and Laplace-Beltrami operators associated to the D9-brane worldvolume fields. These compactifications are T-dual to standard type IIB toroidal orientifolds with NSNS and RR 3-form fluxes and D3/D7 branes. By using techniques of representation theory and harmonic analysis, the spectrum of open string wavefunctions can be computed for Lie groups and their quotients, as we illustrate with explicit twisted tori examples. We find a correspondence between irreducible unitary representations of the Kaloper-Myers algebra and families of Kaluza-Klein excitations. We perform the computation of 2- and 3-point couplings for matter fields in the above flux compactifications, and compare our results with those of 4d effective supergravity.

  2. U-dual fluxes and Generalized Geometry

    CERN Document Server

    Aldazabal, G; Camara, Pablo G; Grana, M

    2010-01-01

    We perform a systematic analysis of generic string flux compactifications, making use of Exceptional Generalized Geometry (EGG) as an organizing principle. In particular, we establish the precise map between fluxes, gaugings of maximal 4d supergravity and EGG, identifying the complete set of gaugings that admit an uplift to 10d heterotic or type IIB supegravity backgrounds. Our results reveal a rich structure, involving new deformations of 10d supergravity backgrounds, such as the RR counterparts of the $\\beta$-deformation. These new deformations are expected to provide the natural extension of the $\\beta$-deformation to full-fledged F-theory backgrounds. Our analysis also provides some clues on the 10d origin of some of the particularly less understood gaugings of 4d supergravity. Finally, we derive the explicit expression for the effective superpotential in arbitrary N = 1 heterotic or type IIB orientifold compactifications, for all the allowed fluxes.

  3. Hamiltonian boundary term and quasilocal energy flux

    International Nuclear Information System (INIS)

    Chen, C.-M.; Nester, James M.; Tung, R.-S.

    2005-01-01

    The Hamiltonian for a gravitating region includes a boundary term which determines not only the quasilocal values but also, via the boundary variation principle, the boundary conditions. Using our covariant Hamiltonian formalism, we found four particular quasilocal energy-momentum boundary term expressions; each corresponds to a physically distinct and geometrically clear boundary condition. Here, from a consideration of the asymptotics, we show how a fundamental Hamiltonian identity naturally leads to the associated quasilocal energy flux expressions. For electromagnetism one of the four is distinguished: the only one which is gauge invariant; it gives the familiar energy density and Poynting flux. For Einstein's general relativity two different boundary condition choices correspond to quasilocal expressions which asymptotically give the ADM energy, the Trautman-Bondi energy and, moreover, an associated energy flux (both outgoing and incoming). Again there is a distinguished expression: the one which is covariant

  4. Evaluating Energy Flux in Vibrofluidized Granular Bed

    Directory of Open Access Journals (Sweden)

    N. A. Sheikh

    2013-01-01

    Full Text Available Granular flows require sustained input of energy for fluidization. A level of fluidization depends on the amount of heat flux provided to the flow. In general, the dissipation of the grains upon interaction balances the heat inputs and the resultant flow patterns can be described using hydrodynamic models. However, with the increase in packing fraction, the heat fluxes prediction of the cell increases. Here, a comparison is made for the proposed theoretical models against the MD simulations data. It is observed that the variation of packing fraction in the granular cell influences the heat flux at the base. For the elastic grain-base interaction, the predictions vary appreciably compared to MD simulations, suggesting the need to accurately model the velocity distribution of grains for averaging.

  5. Warped Kähler potentials and fluxes

    International Nuclear Information System (INIS)

    Martucci, Luca

    2017-01-01

    The four-dimensional effective theory for type IIB warped flux compactifications proposed in https://www.doi.org/10.1007/JHEP03(2015)067 is completed by taking into account the backreaction of the Kähler moduli on the three-form fluxes. The only required modification consists in a flux-dependent contribution to the chiral fields parametrising the Kähler moduli. The resulting supersymmetric effective theory satisfies the no-scale condition and consistently combines previous partial results present in the literature. Similar results hold for M-theory warped compactifications on Calabi-Yau fourfolds, whose effective field theory and Kähler potential are also discussed.

  6. Type IIB flux compactifications on twistor bundles

    Energy Technology Data Exchange (ETDEWEB)

    Imaanpur, Ali, E-mail: aimaanpu@modares.ac.ir

    2014-02-05

    We construct a U(1) bundle over N(1,1), usually considered as an SO(3) bundle on CP{sup 2}, and show that type IIB supergravity can be consistently compactified over it. With the five form flux turned on, there is a solution for which the metric becomes Einstein. We further turn on 3-form fluxes and show that there is a one parameter family of solutions. In particular, there is a limiting solution of large 3-form fluxes for which two U(1) fiber directions of the metric shrink to zero size. We also discuss compactifications over N(1,1) to AdS{sub 3}. All solutions turn out to be non-supersymmetric.

  7. Enumerating Flux Vacua With Enhanced Symmetries

    Energy Technology Data Exchange (ETDEWEB)

    DeWolfe, O.

    2004-11-12

    We study properties of flux vacua in type IIB string theory in several simple but illustrative models. We initiate the study of the relative frequencies of vacua with vanishing superpotential W = 0 and with certain discrete symmetries. For the models we investigate we also compute the overall rate of growth of the number of vacua as a function of the D3-brane charge associated to the fluxes, and the distribution of vacua on the moduli space. The latter two questions can also be addressed by the statistical theory developed by Ashok, Denef and Douglas, and our results are in good agreement with their predictions. Analysis of the first two questions requires methods which are more number-theoretic in nature. We develop some elementary techniques of this type, which are based on arithmetic properties of the periods of the compactification geometry at the points in moduli space where the flux vacua are located.

  8. Atmosphere–Surface Fluxes of CO2 using Spectral Techniques

    DEFF Research Database (Denmark)

    Sørensen, Lise Lotte; Larsen, Søren Ejling

    2010-01-01

    Different flux estimation techniques are compared here in order to evaluate air–sea exchange measurement methods used on moving platforms. Techniques using power spectra and cospectra to estimate fluxes are presented and applied to measurements of wind speed and sensible heat, latent heat and CO2...... fluxes. Momentum and scalar fluxes are calculated from the dissipation technique utilizing the inertial subrange of the power spectra and from estimation of the cospectral amplitude, and both flux estimates are compared to covariance derived fluxes. It is shown how even data having a poor signal......-to-noise ratio can be used for flux estimations....

  9. Sound Science

    Science.gov (United States)

    Sickel, Aaron J.; Lee, Michele H.; Pareja, Enrique M.

    2010-01-01

    How can a teacher simultaneously teach science concepts through inquiry while helping students learn about the nature of science? After pondering this question in their own teaching, the authors developed a 5E learning cycle lesson (Bybee et al. 2006) that concurrently embeds opportunities for fourth-grade students to (a) learn a science concept,…

  10. Software applications for flux balance analysis.

    Science.gov (United States)

    Lakshmanan, Meiyappan; Koh, Geoffrey; Chung, Bevan K S; Lee, Dong-Yup

    2014-01-01

    Flux balance analysis (FBA) is a widely used computational method for characterizing and engineering intrinsic cellular metabolism. The increasing number of its successful applications and growing popularity are possibly attributable to the availability of specific software tools for FBA. Each tool has its unique features and limitations with respect to operational environment, user-interface and supported analysis algorithms. Presented herein is an in-depth evaluation of currently available FBA applications, focusing mainly on usability, functionality, graphical representation and inter-operability. Overall, most of the applications are able to perform basic features of model creation and FBA simulation. COBRA toolbox, OptFlux and FASIMU are versatile to support advanced in silico algorithms to identify environmental and genetic targets for strain design. SurreyFBA, WEbcoli, Acorn, FAME, GEMSiRV and MetaFluxNet are the distinct tools which provide the user friendly interfaces in model handling. In terms of software architecture, FBA-SimVis and OptFlux have the flexible environments as they enable the plug-in/add-on feature to aid prospective functional extensions. Notably, an increasing trend towards the implementation of more tailored e-services such as central model repository and assistance to collaborative efforts was observed among the web-based applications with the help of advanced web-technologies. Furthermore, most recent applications such as the Model SEED, FAME, MetaFlux and MicrobesFlux have even included several routines to facilitate the reconstruction of genome-scale metabolic models. Finally, a brief discussion on the future directions of FBA applications was made for the benefit of potential tool developers.

  11. Can Polar Fields Explain Missing Open Flux?

    Science.gov (United States)

    Linker, J.; Downs, C.; Caplan, R. M.; Riley, P.; Mikic, Z.; Lionello, R.

    2017-12-01

    The "open" magnetic field is the portion of the Sun's magnetic field that extends out into the heliosphere and becomes the interplanetary magnetic field (IMF). Both the IMF and the Sun's magnetic field in the photosphere have been measured for many years. In the standard paradigm of coronal structure, the open magnetic field originates primarily in coronal holes. The regions that are magnetically closed trap the coronal plasma and give rise to the streamer belt. This basic picture is qualitatively reproduced by models of coronal structure using photospheric magnetic fields as input. If this paradigm is correct, there are two primary observational constraints on the models: (1) The open field regions in the model should approximately correspond to coronal holes observed in emission, and (2) the magnitude of the open magnetic flux in the model should match that inferred from in situ spacecraft measurements. Linker et al. (2017, ApJ, submitted) investigated the July 2010 time period for a range of observatory maps and both PFSS and MHD models. We found that all of the model/map combinations underestimated the interplanetary magnetic flux, unless the modeled open field regions were larger than observed coronal holes. An estimate of the open magnetic flux made entirely from solar observations (combining detected coronal hole boundaries with observatory synoptic magnetic maps) also underestimated the interplanetary magnetic flux. The magnetic field near the Sun's poles is poorly observed and may not be well represented in observatory maps. In this paper, we explore whether an underestimate of the polar magnetic flux during this time period could account for the overall underestimate of open magnetic flux. Research supported by NASA, AFOSR, and NSF.

  12. Eddy Correlation Flux Measurement System Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Cook, D. R. [Argonne National Lab. (ANL), Argonne, IL (United States)

    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 components 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.

  13. Wet Deposition Flux of Reactive Organic Carbon

    Science.gov (United States)

    Safieddine, S.; Heald, C. L.

    2016-12-01

    Reactive organic carbon (ROC) is the sum of non-methane volatile organic compounds (NMVOCs) and primary and secondary organic aerosols (OA). ROC plays a key role in driving the chemistry of the atmosphere, affecting the hydroxyl radical concentrations, methane lifetime, ozone formation, heterogeneous chemical reactions, and cloud formation, thereby impacting human health and climate. Uncertainties on the lifecycle of ROC in the atmosphere remain large. In part this can be attributed to the large uncertainties associated with the wet deposition fluxes. Little is known about the global magnitude of wet deposition as a sink of both gas and particle phase organic carbon, making this an important area for research and sensitivity testing in order to better understand the global ROC budget. In this study, we simulate the wet deposition fluxes of the reactive organic carbon of the troposphere using a global chemistry transport model, GEOS-Chem. We start by showing the current modeled global distribution of ROC wet deposition fluxes and investigate the sensitivity of these fluxes to variability in Henry's law solubility constants and spatial resolution. The average carbon oxidation state (OSc) is a useful metric that depicts the degree of oxidation of atmospheric reactive carbon. Here, we present for the first time the simulated gas and particle phase OSc of the global troposphere. We compare the OSc in the wet deposited reactive carbon flux and the dry deposited reactive carbon flux to the OSc of atmospheric ROC to gain insight into the degree of oxidation in deposited material and, more generally, the aging of organic material in the troposphere.

  14. Depicting CH4 fluxes and drivers dynamics

    Science.gov (United States)

    Dengel, S.; Billesbach, D. P.; Hughes, H.; Humphreys, E.; Lee, J.; Noormets, A.; Verfaillie, J. G.

    2016-12-01

    Since the advancement in CH4 eddy covariance flux measurements, monitoring of CH4 emissions is becoming more widespread. Since CH4 fluxes are not as predictable or as easily interpretable as CO2 fluxes, understanding their emission patterns often still challenging. As these are spatially (ecosystem and latitudinal) and temporal very divers and often event based, a better understanding or interpretation of results is required. An improvement in understanding does also increase the reliability of gap-filling methods as annual greenhouse gas budgets rely on high quality data. There are generalised additive models (Wood 2001) that can easily be applied to sites, models where a relationship between the response variable, in this case CH4 and explanatory variables (drivers) is established. Relevant for CH4flux dynamics are the smoothing function that is applied, where each predictor variable is separated into sections and a polynomial function fitted. On the one hand such models are rarely used as they are difficult to interpret since no parameter values are retuned. On the other hand, such models are very good for prediction and explanatory analysis in estimating the functional nature of a response. Applying such models to CH4 eddy flux data does improve our understanding of the dynamics of CH4 emissions and the respective meteorological drivers. Furthermore, such models combined with tree models (interactions between the explanatory variables), can visualise precise dynamics and easily applied to individual sites. These models are simple tools in understanding of these complex fluxes, as they can include a variety of drivers, and their relevance tested by the model. Model input variables should be as independent as possible (avoiding cross-correlation), avoiding redundant inputs, as models should follow the principle of parsimony of being simple but not too simple. Wood SN (2001). mgcv: GAMs and generalized ridge regression for R. R news.

  15. Quantitative aspect in circulation type classifications – An example based on evaluation of moisture flux anomalies

    Czech Academy of Sciences Publication Activity Database

    Müller, Miloslav; Kašpar, Marek

    2010-01-01

    Roč. 35, 9-12 (2010), s. 484-490 ISSN 1474-7065 R&D Projects: GA AV ČR KJB300420701; GA AV ČR KJB300420802 Institutional research plan: CEZ:AV0Z30420517 Keywords : Circulation type classification * moisture flux * extreme precipitation * extremeness of meteorological variables, seasonality of heavy rains * seasonality of heavy rains Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.917, year: 2010

  16. Solar flux variation of the electron temperature morning overshoot in the equatorial F region

    Czech Academy of Sciences Publication Activity Database

    Stolle, C.; Liu, H.; Truhlík, Vladimír; Lühr, H.; Richards, G.

    2011-01-01

    Roč. 116, - (2011), A04308/1-A04308/13 ISSN 0148-0227 R&D Projects: GA ČR GAP209/10/2086 Institutional research plan: CEZ:AV0Z30420517 Keywords : IONOSPHERIC PHOTOELECTRON FLUX * MODEL * DENSITY * ATMOSPHERE * ION Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.021, year: 2011 http://www.agu.org/pubs/crossref/2011/2010JA016235.shtml

  17. HELCZA-High heat flux test facility for testing ITER EU first wall components.

    Czech Academy of Sciences Publication Activity Database

    Prokůpek, J.; Samec, K.; Jílek, R.; Gavila, P.; Neufuss, S.; Entler, Slavomír

    2017-01-01

    Roč. 124, November (2017), s. 187-190 ISSN 0920-3796. [SOFT 2016: Symposium on Fusion Technology /29./. Prague, 05.09.2016-09.09.2016] Institutional support: RVO:61389021 Keywords : HELCZA * High heat flux * Electron beam testing * Test facility * Plasma facing components * First wall * Divertora Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 1.319, year: 2016 www.sciencedirect.com/science/article/pii/S0920379617302818

  18. Diffusive flux of energy in binary mixtures

    International Nuclear Information System (INIS)

    Sampaio, R.S.

    1976-04-01

    The diffusive flux of energy j tilde is studied through the reduced diffusive flux of energy K tilde, which obeys equations of the form: sim(delta K tilde/delta grad rho sub(α))= sim(delta K tilde/delta grad theta)=0. By a representation theorem, herein proved, is obtained a general representation for K tilde which is simplified, for the case of binary mixtures, using the principle of objectivity. Some consequences of this representation are discussed such as the symmetry of the partial stresses T 1 tilde and T 2 tilde and the difference between the normal stresses [pt

  19. Observation of a Coulomb flux tube

    Science.gov (United States)

    Greensite, Jeff; Chung, Kristian

    2018-03-01

    In Coulomb gauge there is a longitudinal color electric field associated with a static quark-antiquark pair. We have measured the spatial distribution of this field, and find that it falls off exponentially with transverse distance from a line joining the two quarks. In other words there is a Coulomb flux tube, with a width that is somewhat smaller than that of the minimal energy flux tube associated with the asymptotic string tension. A confinement criterion for gauge theories with matter fields is also proposed.

  20. Atmospheric electron flux at airplane altitude

    International Nuclear Information System (INIS)

    Enomoto, R.; Chiba, J.; Ogawa, K.; Sumiyoshi, T.; Takasaki, F.; Kifune, T.; Matsubara, Y.; Nishimura, J.

    1991-01-01

    We have developed a new detector to systematically measure the cosmic-ray electron flux at airplane altitudes. We loaded a lead-glass-based electron telescope onto a commercial cargo airplane. The first experiment was carried out using the air route between Narita (Japan) and Sydney (Australia); during this flight we measured the electron flux at various altitudes and latitudes. The thresholds of the electron energies were 1, 2, and 4 GeV. The results agree with a simple estimation using one-dimensional shower theory. A comparison with a Monte Carlo calculation was made

  1. Growth of zircaloy 4 under neutron flux

    International Nuclear Information System (INIS)

    Morize, P.; Baicry, J.; Morlot, G.; Sciers, P.; Lehmann, D.

    1982-06-01

    Between 300 and 385 0 C, and under neutron fluxes between 0.5 and 2.10 14 n/cm 2 /s, the growth of zircaloy tubes is nil in the plane perpendicular to the axis, and can be represented by the equation: Δl/l=4.6610 -14 (phit)sup(0.49) in the axial direction. In the area investigated, neither the irradiation temperature nor the instantaneous flux has any effect on the metallurgical state (relieved or recrystallized) [fr

  2. Dual neutron flux/temperature measurement sensor

    Science.gov (United States)

    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.

  3. Gravitational effects on planetary neutron flux spectra

    Science.gov (United States)

    Feldman, W. C.; Drake, D. M.; O'Dell, R. D.; Brinkley, F. W., Jr.; Anderson, R. C.

    1989-01-01

    The effects of gravity on the planetary neutron flux spectra for planet Mars, and the lifetime of the neutron, were investigated using a modified one-dimensional diffusion accelerated neutral-particle transport code, coupled with a multigroup cross-section library tailored specifically for Mars. The results showed the presence of a qualitatively new feature in planetary neutron leakage spectra in the form of a component of returning neutrons with kinetic energies less than the gravitational binding energy (0.132 eV for Mars). The net effect is an enhancement in flux at the lowest energies that is largest at and above the outermost layer of planetary matter.

  4. Flux pinning characteristics of YBCO coated conductor

    International Nuclear Information System (INIS)

    Matsushita, T.; Watanabe, T.; Fukumoto, Y.; Yamauchi, K.; Kiuchi, M.; Otabe, E.S.; Kiss, T.; Watanabe, T.; Miyata, S.; Ibi, A.; Muroga, T.; Yamada, Y.; Shiohara, Y.

    2005-01-01

    Flux pinning properties of PLD-processed YBCO coated conductors deposited on IBAD substrate are investigated. The thickness of YBCO layer is changed in the range of 0.27-1.0 μm. The thickness dependence of critical current density, n-value and irreversibility field are measured in a wide range of magnetic field. The results are compared with the theoretical flux creep-flow model. It is found that these pinning properties are strongly influenced by the thickness as well as the pinning strength. Optimum condition for high field application of this superconductor is discussed

  5. Flux pinning and flux flow studies in superconductors using flux flow noise techniques. Progress report, April 1-December 30, 1979

    International Nuclear Information System (INIS)

    Joiner, W.C.H.

    1979-12-01

    Flux flow noise power spectra were investigated, and information obtained through such spectra is applied to describe flux flow and pinning in situations where volume pinning force data is also available. In one case, the application of noise data to PB 80 In 20 samples after recovery and after high temperature annealing is discussed. This work is consistent with a recent model for flux flow noise generation. In the second case we discuss experiments designed to change the fluxoid transit path length, which according to the model should affect both the noise amplitude and the parameter α specifying the longest subpulse times in terms of the average transit time, tau/sub c/. Transient flux flow voltages when a current is switched on after field cycling a Pb 60 In 40 sample have been discovered. Noise spectra have been measured during the transient. These observations are discussed along with a simple model which fits the data. A surprising result is that the transient decay times increase with the applied current. Other characteristics of Pb 60 In 40 after cold working are also discussed

  6. An Overview of Flux Pumps for HTS Coils

    OpenAIRE

    Coombs, Timothy Arthur; Geng, Jianzhao; Fu, L; Matsuda, K

    2016-01-01

    High-Tc superconducting (HTS) flux pumps are capable of injecting flux into closed HTS magnets without electrical contact. It is becoming a promising alternative of current source in powering HTS coils. This paper reviews the recent progress in flux pumps for HTS coil magnets. Different types of HTS flux pumps are introduced. The physics of these flux pumps are explained and comparisons are made. J. Geng would like to acknowledge Cambridge Trust for offering Cambridge International Scholar...

  7. Flux and seasonality of planktonic foraminifera in the Xisha Trough, South China Sea

    Science.gov (United States)

    Xiang, R.; Chen, M.; Wang, D.; Chen, Z.; Yan, W.

    2013-12-01

    The modern correlation between planktonic foraminiferal community dynamics and environmental conditions may provide a basis for establishing paleoclimatic proxies. We studied planktic foraminiferal shell fluxes and assemblages in samples collected in a time-series sediment trap deployments in the Xisha Trough, South China Sea (SCS), from June 2009 to August 2011. The general flux shows a unimodal pattern, with high planktonic foraminiferal flux (900-1000 tests m-2 day-1) occurs during the period from late September/October to February, and low flux (200-300 tests m-2 day-1)during the rest period of the year. This flux pattern is contrast to the bimodal pattern of planktonic foraminiferal flux obtained from the central and southern SCS. Ten species, Globigeroides sacculifer, Globigerinoides ruber, Pulleniatina obliquiloculata, Neogloboquadrina dutertrei, Globigerina calida, Globigerinella aequilateralis, Globigerina bulloides, Globigerinita glutinata, Orbulina univera and Globorotalia menardii, contributed about 96% of the total flux in each year. Among them, the monsoonal driven seasonality is most prominent for P. obliquiloculata, N. dutertrei and G. bulloides, with more than 70% of their species-specific total fluxes (93% for G. bulloides) occur from late September/October to February. This suggests G. bulloides can be used as a winter proxy-species. On the contrary, Globigeroides conglobatus, mostly appeared during June to August. G. sacculifer, G. ruber and G. aequilateralis generally follow the trend of the total flux of planktonic foraminifer, with about 50-60% of their total fluxes occur from late September/October to February. We also compared the size distribution of the dominant foraminiferal species in the > 250 micrometer fraction and 250-154 micrometer fraction, we found that most shells of G. aequilateralis, O. univera and G. menardii, and G. conglobatus mainly occur in the >250 micrometer fraction, and about 40% of G. sacculifer, 35% of P

  8. Legalising science.

    Science.gov (United States)

    Tallacchini, Mariachiara

    2002-01-01

    The legal view of science has changed through time, moving from a positivist and noncritical position of law towards science to a critical view of science--providing the potential for more objective knowledge, but value-laden as well--and of the role of society. This paper explores some judicial cases that illustrate these attitudes, suggesting that reference to science (particularly to EBM) can be rigorously and equitably made when it serves the cause of transparency and democratisation both in science and in law.

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

    Science.gov (United States)

    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

  10. A flux footprint analysis to understand ecosystem fluxes in an intensively managed landscape

    Science.gov (United States)

    Hernandez Rodriguez, L. C.; Goodwell, A. E.; Kumar, P.

    2017-12-01

    Flux tower studies in agricultural sites have mainly been done at plot scale, where the footprint of the instruments is small such that the data reveals the behaviour of the nearby crop on which the study is focused. In the Midwestern United States, the agricultural ecosystem and its associated drainage, evapotranspiration, and nutrient dynamics are dominant influences on interactions between the soil, land, and atmosphere. In this study, we address large-scale ecohydrologic fluxes and states in an intensively managed landscape based on data from a 25m high eddy covariance flux tower. We show the calculated upwind distance and flux footprint for a flux tower located in Central Illinois as part of the Intensively Managed Landscapes Critical Zone Observatory (IMLCZO). In addition, we calculate the daily energy balance during the summer of 2016 from the flux tower measurements and compare with the modelled energy balance from a representative corn crop located in the flux tower footprint using the Multi-Layer Canopy model, MLCan. The changes in flux footprint over the course of hours, days, and the growing season have significant implications for the measured fluxes of carbon and energy at the flux tower. We use MLCan to simulate these fluxes under land covers of corn and soybeans. Our results demonstrate how the instrument heights impact the footprint of the captured eddy covariance fluxes, and we explore the implication for hydrological analysis. The convective turbulent atmosphere during the daytime shows a wide footprint of more than 10 km2, which reaches 3km length for the 90% contribution, where buoyancy is the dominant mechanism driving turbulence. In contrast, the stable atmosphere during the night-time shows a narrower footprint that goes beyond 8km2 and grows in the direction of the prevalent wind, which exceeds 4 km in length. This study improves our understanding of agricultural ecosystem behaviour in terms of the magnitude and variability of fluxes and

  11. Teaching sciences: The multicultural question revisited

    Science.gov (United States)

    Stanley, William B.; Brickhouse, Nancy W.

    2001-01-01

    We contend that science education should be multicultural. We do not believe a universalist view of science is either compatible with a multicultural approach or fully coherent as a foundation for the science curriculum. We begin by summarizing the case for a universalist approach to science education. We then show weaknesses of universalism in accounting for the following: 1. the limits of human cognitive capabilities in constraining what we can understand about nature; 2. a description of reality as a flux; 3. the disunity of science and the role of culturally different forms and social organization of research in shaping the cognitive content of the sciences. We argue that it would be valuable for students to understand the nature of the debates regarding multicultural and universalist perspectives on science. For example, what questions is contemporary molecular biology good at answering? What kinds of problems do other sciences solve? What historical conditions may explain why western sciences arose primarily out of Western European culture rather than elsewhere in the world? How do other belief systems (e.g., religion) interact with indigenous sciences, Chinese science, and Western science?

  12. Science Teaching in Science Education

    Science.gov (United States)

    Callahan, Brendan E.; Dopico, Eduardo

    2016-01-01

    Reading the interesting article "Discerning selective traditions in science education" by Per Sund, which is published in this issue of "CSSE," allows us to open the discussion on procedures for teaching science today. Clearly there is overlap between the teaching of science and other areas of knowledge. However, we must…

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

    Science.gov (United States)

    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

  14. Apparatus for measuring low thermal fluxes

    International Nuclear Information System (INIS)

    Aranovitch, R.; Warnery, M.

    1972-01-01

    Device for the measurement of slight wall heat fluxes, made up of a metallic contact plate combined with a shaft; temperature measurement elements are spaced along the shaft which is kept at a cold adjustable reference temperature lower than that of the walls; heat insulation is provided for the exposed part of the plate and for the shaft [fr

  15. Terrestrial water fluxes dominated by transpiration: Comment

    Science.gov (United States)

    Daniel R. Schlaepfer; Brent E. Ewers; Bryan N. Shuman; David G. Williams; John M. Frank; William J. Massman; William K. Lauenroth

    2014-01-01

    The fraction of evapotranspiration (ET) attributed to plant transpiration (T) is an important source of uncertainty in terrestrial water fluxes and land surface modeling (Lawrence et al. 2007, Miralles et al. 2011). Jasechko et al. (2013) used stable oxygen and hydrogen isotope ratios from 73 large lakes to investigate the relative roles of evaporation (E) and T in ET...

  16. EUV mirror based absolute incident flux detector

    Science.gov (United States)

    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.

  17. Solitary wave propagation in solar flux tubes

    International Nuclear Information System (INIS)

    Erdelyi, Robert; Fedun, Viktor

    2006-01-01

    The aim of the present work is to investigate the excitation, time-dependent dynamic evolution, and interaction of nonlinear propagating (i.e., solitary) waves on vertical cylindrical magnetic flux tubes in compressible solar atmospheric plasma. The axisymmetric flux tube has a field strength of 1000 G at its footpoint, which is typical for photospheric regions. Nonlinear waves that develop into solitary waves are excited by a footpoint driver. The propagation of the nonlinear signal is investigated by solving numerically a set of fully nonlinear 2.0D magnetohydrodynamic (MHD) equations in cylindrical coordinates. For the initial conditions, axisymmetric solutions of the linear dispersion relation for wave modes in a magnetic flux tube are applied. In the present case, we focus on the sausage mode only. The dispersion relation is solved numerically for a range of plasma parameters. The equilibrium state is perturbed by a Gaussian at the flux tube footpoint. Two solitary solutions are found by solving the full nonlinear MHD equations. First, the nonlinear wave propagation with external sound speed is investigated. Next, the solitary wave propagating close to the tube speed, also found in the numerical solution, is studied. In contrast to previous analytical and numerical works, here no approximations were made to find the solitary solutions. A natural application of the present study may be spicule formation in the low chromosphere. Future possible improvements in modeling and the relevance of the photospheric chromospheric transition region coupling by spicules is suggested

  18. Annual Cycles of Surface Shortwave Radiative Fluxes

    Science.gov (United States)

    Wilber, Anne C.; Smith, G. Louis; Gupta, Shashi K.; Stackhouse, Paul W.

    2006-01-01

    The annual cycles of surface shortwave flux are investigated using the 8-yr dataset of the surface radiation budget (SRB) components for the period July 1983-June 1991. These components include the downward, upward, and net shortwave radiant fluxes at the earth's surface. The seasonal cycles are quantified in terms of principal components that describe the temporal variations and empirical orthogonal functions (EOFs) that describe the spatial patterns. The major part of the variation is simply due to the variation of the insolation at the top of the atmosphere, especially for the first term, which describes 92.4% of the variance for the downward shortwave flux. However, for the second term, which describes 4.1% of the variance, the effect of clouds is quite important and the effect of clouds dominates the third term, which describes 2.4% of the variance. To a large degree the second and third terms are due to the response of clouds to the annual cycle of solar forcing. For net shortwave flux at the surface, similar variances are described by each term. The regional values of the EOFs are related to climate classes, thereby defining the range of annual cycles of shortwave radiation for each climate class.

  19. Optimal flux patterns in cellular metabolic networks

    Energy Technology Data Exchange (ETDEWEB)

    Almaas, E

    2007-01-20

    The availability of whole-cell level metabolic networks of high quality has made it possible to develop a predictive understanding of bacterial metabolism. Using the optimization framework of flux balance analysis, I investigate metabolic response and activity patterns to variations in the availability of nutrient and chemical factors such as oxygen and ammonia by simulating 30,000 random cellular environments. The distribution of reaction fluxes is heavy-tailed for the bacteria H. pylori and E. coli, and the eukaryote S. cerevisiae. While the majority of flux balance investigations have relied on implementations of the simplex method, it is necessary to use interior-point optimization algorithms to adequately characterize the full range of activity patterns on metabolic networks. The interior-point activity pattern is bimodal for E. coli and S. cerevisiae, suggesting that most metabolic reaction are either in frequent use or are rarely active. The trimodal activity pattern of H. pylori indicates that a group of its metabolic reactions (20%) are active in approximately half of the simulated environments. Constructing the high-flux backbone of the network for every environment, there is a clear trend that the more frequently a reaction is active, the more likely it is a part of the backbone. Finally, I briefly discuss the predicted activity patterns of the central-carbon metabolic pathways for the sample of random environments.

  20. Predicting flux decline of reverse osmosis membranes

    NARCIS (Netherlands)

    Schippers, J.C.; Hanemaayer, J.H.; Smolders, C.A.; Kostense, A.

    1981-01-01

    A mathematical model predicting flux decline of reverse osmosis membranes due to colloidal fouling has been verified. This mathema- tical model is based on the theory of cake or gel filtration and the Modified Fouling Index (MFI). Research was conducted using artificial colloidal solutions and a

  1. Self-powered neutron flux detector assembly

    International Nuclear Information System (INIS)

    Allan, C.J.; McIntyre, I.L.

    1980-01-01

    A self-powered neutron flux detector has both the central emitter electrode and its surrounding collector electrode made of inconel 600. The lead cables may also be made of inconel. Other nickel alloys, or iron, nickel, titamium, chromium, zirconium or their alloys may also be used for the electrodes

  2. Radiation linewidth of flux-flow oscillators

    DEFF Research Database (Denmark)

    Koshelets, V.P.; Dmitriev, P.N.; Ermakov, A.B.

    2001-01-01

    (applied magnetic field) are taken. A profile of the FFO radiation line is measured in different regimes of FFO operation and compared to the theoretical models. A Lorentzian shape of the FFO line is observed both at Fiske steps (FSs) in the resonant regime and on the flux-flow step (FFS) at high voltages...

  3. SLC positron source flux concentrator modulator

    International Nuclear Information System (INIS)

    de Lamare, J.; Kulikov, A.; Cassel, R.; Nesterov, V.

    1991-06-01

    The modulator for the SLC e+ source flux concentrator provides 16 kA in a 5 μs sinusoidal half wave current for a pure inductive load, at 120 Hz. The modulator incorporates 10 EEV CX1622 thyratrons in a switching network. It provides reliable operation with acceptable thyratron lifetime. 3 refs., 3 figs., 1 tab

  4. AVERAGE FLUXES FROM HETEROGENEOUS VEGETATED REGIONS

    NARCIS (Netherlands)

    KLAASSEN, W

    Using a surface-layer model, fluxes of heat and momentum have been calculated for flat regions with regularly spaced step changes in surface roughness and stomatal resistance. The distance between successive step changes is limited to 10 km in order to fill the gap between micro-meteorological

  5. Models of Flux Tubes from Constrained Relaxation

    Indian Academy of Sciences (India)

    tribpo

    J. Astrophys. Astr. (2000) 21, 299 302. Models of Flux Tubes from Constrained Relaxation. Α. Mangalam* & V. Krishan†, Indian Institute of Astrophysics, Koramangala,. Bangalore 560 034, India. *e mail: mangalam @ iiap. ernet. in. † e mail: vinod@iiap.ernet.in. Abstract. We study the relaxation of a compressible plasma to ...

  6. Optical magnetic flux generation in superconductor

    Indian Academy of Sciences (India)

    Abstract. The generation of the magnetic flux quanta inside the superconductors is studied as a new effect to destroy superconductivity using femtosecond (fs) laser. The vortices are successfully generated in the YBa2Cu3O7−δ thin film striplines by the fs laser. It is revealed that the vortex distribution in the strip reflects the fs ...

  7. Examining gas flux responses to restoration

    Science.gov (United States)

    Wetlands play an important role in the flux of gases such as carbon dioxide, methane, and nitrous oxide. Wetland ecosystems are characterized by slow decomposition and, often, high productivity, making them net sinks of carbon dioxide. However, under some conditions, such as ti...

  8. Modelling radiocesium fluxes in forest ecosystems

    International Nuclear Information System (INIS)

    Shaw, G.; Kliashtorin, A.; Mamikhin, S.; Shcheglov, A.; Rafferty, B.; Dvornik, A.; Zhuchenko, T.; Kuchma, N.

    1996-01-01

    Monitoring of radiocesium inventories and fluxes has been carried out in forest ecosystems in Ukraine, Belarus and Ireland to determine distributions and rates of migration. This information has been used to construct and calibrate mathematical models which are being used to predict the likely longevity of contamination of forests and forest products such as timber following the Chernobyl accident

  9. MAGNETIC FLUX CANCELLATION IN ELLERMAN BOMBS

    Energy Technology Data Exchange (ETDEWEB)

    Reid, A.; Mathioudakis, M.; Nelson, C. J.; Henriques, V. [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, BT7 1NN, Northern Ireland (United Kingdom); Doyle, J. G. [Armagh Observatory, College Hill, Armagh, BT61 9DG (United Kingdom); Scullion, E. [Trinity College Dublin, College Green, Dublin 2 (Ireland); Ray, T., E-mail: areid29@qub.ac.uk [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland)

    2016-06-01

    Ellerman Bombs (EBs) are often found to be co-spatial with bipolar photospheric magnetic fields. We use H α imaging spectroscopy along with Fe i 6302.5 Å spectropolarimetry from the Swedish 1 m Solar Telescope (SST), combined with data from the Solar Dynamic Observatory , to study EBs and the evolution of the local magnetic fields at EB locations. EBs are found via an EB detection and tracking algorithm. Using NICOLE inversions of the spectropolarimetric data, we find that, on average, (3.43 ± 0.49) × 10{sup 24} erg of stored magnetic energy disappears from the bipolar region during EB burning. The inversions also show flux cancellation rates of 10{sup 14}–10{sup 15} Mx s{sup −1} and temperature enhancements of 200 K at the detection footpoints. We investigate the near-simultaneous flaring of EBs due to co-temporal flux emergence from a sunspot, which shows a decrease in transverse velocity when interacting with an existing, stationary area of opposite polarity magnetic flux, resulting in the formation of the EBs. We also show that these EBs can be fueled further by additional, faster moving, negative magnetic flux regions.

  10. Demystifying Electric Flux and Gauss's Law

    Science.gov (United States)

    McManus, Jeff

    2017-01-01

    Many physics students have experienced the difficulty of internalizing concepts in electrostatics. After studying concrete, measurable details in mechanics, they are challenged by abstract ideas such as electric fields, flux, Gauss's law, and electric potential. There are a few well-known hands-on activities that help students get experience with…

  11. What controls sediment flux in dryland channels?

    Science.gov (United States)

    Michaelides, K.; Singer, M. B.

    2010-12-01

    Theories for the development of longitudinal and grain size profiles in perennial fluvial systems are well developed, allowing for generalization of sediment flux and sorting in these fluvial systems over decadal to millennial time scales under different forcings (e.g., sediment supply, climate changes, etc). However, such theoretical frameworks are inadequate for understanding sediment flux in dryland channels subject to spatially and temporally discontinuous streamflow, where transport capacity is usually much lower than sediment supply. In such fluvial systems, channel beds are poorly sorted with weak vertical layering, poorly defined bar forms, minimal downstream fining, and straight longitudinal profiles. Previous work in dryland channels has documented sediment flux at higher rates than their humid counterparts once significant channel flow develops, pulsations in bed material transport under constant discharge, and oscillations in dryland channel width that govern longitudinal patterns in erosion and deposition. These factors point to less well appreciated controls on sediment flux in dryland valley floors that invite further study. This paper investigates the relative roles of hydrology, bed material grain size, and channel width on sediment flux rates in the Rambla de Nogalte in southeastern Spain. Topographic valley cross sections and hillslope and channel particle sizes were collected from an ephemeral-river reach. Longitudinal grain-size variation on the hillslopes and on the channel bed were analysed in order to determine the relationship between hillslope supply characteristics and channel grain-size distribution and longitudinal changes. Local fractional estimates of bed-material transport in the channel were calculated using a range of channel discharge scenarios in order to examine the effect of channel hydrology on sediment transport. Numerical modelling was conducted to investigate runoff connectivity from hillslopes to channel and to examine the

  12. Carbon and energy fluxes of the understory vegetation of the black spruce ecosystem in interior Alaska

    Science.gov (United States)

    Ikawa, H.; Nakai, T.; Kim, Y.; Busey, R.; Suzuki, R.; Hinzman, L. D.

    2013-12-01

    Underlain by permafrost, understory vegetation in the boreal forest of the high northern latitudes is likely sensitive to climate change. This study investigated the contribution of the understory vegetation of the black spruce forest (Picea mariana) to net ecosystem exchange (NEE) and vertical energy fluxes at the supersite (65deg 07' 24' N, 147deg 29' 15' W) of the JAMSTEC-IARC Collaboration Study (JICS) located within the property of the Poker Flat Research Range of the University of Alaska Fairbanks in interior Alaska [Sugiura et al., 2011; Nakai et al., 2013]. The understory is dominated by a 0 - 20 cm thick layer of peat moss (Sphagnum fuscum) and feather moss (Hylocomium splendens). Eddy covariance measurements were made at 11 m over the canopy and 1.9 m above the ground in summer 2013. The measurement shows that the peak sink of CO2 from understory during the day typically accounted for 80% of the total NEE of (~ 3 μmol m-2s-1) observed over the canopy. Sensible heat flux was nearly identical between the two heights and latent heat flux observed at 1.9m was slightly higher than that observed at 11m. Higher latent heat flux from understory than the total latent heat flux over the canopy is most likely due to the difference in the footprint of the two measurements, and it is necessary to further evaluate the spatial representativeness of the understory fluxes. Nonetheless, these high flux values from the understory suggest an importance of the understory vegetation in evaluating ecosystem flux of the black spruce forest. Acknowledgement This study is funded by the Japan Aerospace Exploration Agency (JAXA) and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) References Nakai, T., Y. Kim, R. C. Busey, R. Suzuki, S. Nagai, H. Kobayashi, H. Park, K. Sugiura, and A. Ito (2013), Characteristics of evapotranspiration from a permafrost black spruce forest in interior Alaska, Polar Science, 7(2), 136-148, doi:10.1016/j.polar.2013.03.003. Sugiura, K

  13. The Solar-flux Third Granulation Signature

    Science.gov (United States)

    Gray, David F.; Oostra, Benjamin

    2018-01-01

    The velocity shifts of spectral lines as a function of line strength, so-called the third signature of granulation, are investigated using three published solar-flux atlases. We use flux atlases because we wish to treat the Sun as a star, against which stellar observations can be compared and judged. The atlases are critiqued and compared to the lower-resolution observations taken with the Elginfield stellar spectrograph. Third-signature plots are constructed for the 6020–6340 Å region. No dependence on excitation potential or wavelength is found over this wavelength span. The shape of the plots from the three solar atlases is essentially the same, with rms line-core velocity differences of 30–35 m s‑1. High-resolution atlas data are degraded to the level of the Elginfield spectrograph and compared to direct observations taken with that spectrograph. The line-core velocities show good agreement, with rms differences of 38 m s‑1. A new standard curve is derived and compared with the previously published one. Only small differences in shape are found, but a significant (+97 m s‑1) change in the zero point is indicated. The bisector of the Fe I 6253 line is mapped onto the third-signature plots and flux deficits are derived, which measure the granule/lane flux imbalance. The lower spectral resolution lowers the flux deficit area slightly and moves the peak of the deficit 0.3–0.5 km s‑1 toward higher velocities. These differences, while significant, are not large compared to measurement errors for stellar data.

  14. Flux trapping and shielding in irreversible superconductors

    International Nuclear Information System (INIS)

    Frankel, D.J.

    1978-05-01

    Flux trappings and shielding experiments were carried out on Pb, Nb, Pb-Bi, Nb-Sn, and Nb-Ti samples of various shapes. Movable Hall probes were used to measure fields near or inside the samples as a function of position and of applied field. The trapping of transverse multipole magnetic fields in tubular samples was accomplished by cooling the samples in an applied field and then smoothly reducing the applied field to zero. Transverse quadrupole and sextupole fields with gradients of over 2000 G/cm were trapped with typical fidelity to the original impressed field of a few percent. Transverse dipole fields of up to 17 kG were also trapped with similar fidelity. Shielding experiments were carried out by cooling the samples in zero field and then gradually applying an external field. Flux trapping and shielding abilities were found to be limited by two factors, the pinning strength of the material, and the susceptibility of a sample to flux jumping. The trapping and shielding behavior of flat disk samples in axial fields and thin-walled tubular samples in transverse fields was modeled. The models, which were based on the concept of the critical state, allowed a connection to be made between the pinning strength and critical current level, and the flux trapping and shielding abilities. Adiabatic and dynamic stability theories are discussed and applied to the materials tested. Good qualitative, but limited quantitative agreement was obtained between the predictions of the theoretical stability criteria and the observed flux jumping behavior

  15. How Giant Magnetospheres Maintain Their Magnetic Flux.

    Science.gov (United States)

    Rymer, A. M.

    2017-12-01

    Magnetic flux lost from a planet must be returned [Maxwell's first law, there are no magnetic monopoles (div(B) = 0)], and the dominant mechanism by which this is achieved is still to be determined. Here we compare a mechanism for magnetic flux return via small-scale plasma circulation. The existence of bi-modal superposed electron distributions at Jupiter and Saturn was a surprise to Voyager researchers [e.g. Sittler et al., 1983] that remains something of a mystery to this day. Electrons are virtually massless and are expected to rapidly thermalize to a single distribution. Observations by the Cassini spacecraft at Saturn have elucidated on the source of the hot electron component - small scale isolated flux tubes (commonly referred to as `injection events') that bubble planetward, returning magnetic flux that had been convected outward by centrifugal forces or stripped away during magnetospheric reconfigurations, such as substorms [Rymer et al., 2008]. Saturn is an ideal place to study injection events; relatively quiescent, aligned magnetic and geographic spins axes and a nice fast rotation rate in comparison to plasma drift speeds. The other magnetospheric laboratories in our solar system (Jupiter, Uranus and Neptune) will be more challenging. In this presentation we describe predictions for how plasma injection will be manifest as a function of magnetic field strength, topology and planetary spin rate and its importance in conservation of magnetic flux globally. Sittler, E. C., Jr., K. W. Ogilvie, and J. D. Scudder, 1983. Survey of low-energy plasma electrons in Saturn's magnetosphere: Voyager 1 and 2, J. Geophys. Res., 88, 8847- 8870. Rymer, A. M., Mauk, B. H. , Hill, T. W., Paranicas, C., Mitchell, D. G., Coates, A. J., Young, D. T. , 2008. Electron circulation in Saturn's magnetosphere. J. Geophys. Res.113, A01201.

  16. Comparison between Evapotranspiration Fluxes Assessment Methods

    Science.gov (United States)

    Casola, A.; Longobardi, A.; Villani, P.

    2009-11-01

    Knowledge of hydrological processes acting in the water balance is determinant for a rational water resources management plan. Among these, the water losses as vapour, in the form of evapotranspiration, play an important role in the water balance and the heat transfers between the land surface and the atmosphere. Mass and energy interactions between soil, atmosphere and vegetation, in fact, influence all hydrological processes modificating rainfall interception, infiltration, evapotraspiration, surface runoff and groundwater recharge.A numbers of methods have been developed in scientific literature for modelling evapotranspiration. They can be divided in three main groups: i) traditional meteorological models, ii) energy fluxes balance models, considering interaction between vegetation and the atmosphere, and iii) remote sensing based models. The present analysis preliminary performs a study of fluxes directions and an evaluation of energy balance closure in a typical Mediterranean short vegetation area, using data series recorded from an eddy covariance station, located in the Campania region, Southern Italy. The analysis was performed on different seasons of the year with the aim to assess climatic forcing features impact on fluxes balance, to evaluate the smaller imbalance and to highlight influencing factors and sampling errors on balance closure. The present study also concerns evapotranspiration fluxes assessment at the point scale. Evapotranspiration is evaluated both from empirical relationships (Penmann-Montheit, Penmann F AO, Prestley&Taylor) calibrated with measured energy fluxes at mentioned experimental site, and from measured latent heat data scaled by the latent heat of vaporization. These results are compared with traditional and reliable well known models at the plot scale (Coutagne, Turc, Thorthwaite).

  17. Nanofins science and applications

    CERN Document Server

    Singh, Navdeep

    2014-01-01

    Nanofins Science and Technology describes the heat transfer effectiveness of polymer coolants and their fundamental interactions with carbon nanotube coatings that act as nanofins. Heat transfer at micro/nano-scales has attracted significant attention in contemporary literature. This has been primarily driven by industrial requirements where significant decrease in the size of electronic devices/chips with concomitant enhancement in the heat flux have caused challenging needs for cooling of these platforms. With quantum effects kicking in, traditional cooling techniques need to be replaced with more effective technologies. A promising technique is to enhance heat transfer by surface texturing using nanoparticle coatings or engineered nanostructures. These nanostructures are termed as nanofins because they augment heat transfer by a combination of surface area enhancement as well as liquid-solid interactions at the molecular scale.

  18. Field-scale evaluation of water fluxes and manure solution leaching in feedlot pen soils.

    Science.gov (United States)

    García, Ana R; Maisonnave, Roberto; Massobrio, Marcelo J; Fabrizio de Iorio, Alicia R

    2012-01-01

    Accumulation of beef cattle manure on feedlot pen surfaces generates large amounts of dissolved solutes that can be mobilized by water fluxes, affecting surface and groundwater quality. Our objective was to examine the long-term impacts of a beef cattle feeding operation on water fluxes and manure leaching in feedlot pens located on sandy loam soils of the subhumid Sandy Pampa region in Argentina. Bulk density, gravimetric moisture content, and chloride concentration were quantified. Rain simulation trials were performed to estimate infiltration and runoff rates. Using chloride ion as a tracer, profile analysis techniques were applied to estimate the soil moisture flux and manure conservative chemical components leaching rates. An organic stratum was found over the surface of the pen soil, separated from the underlying soil by a highly compacted thin layer (the manure-soil interface). The soil beneath the organic layer showed greater bulk density in the A horizon than in the control soil and had greater moisture content. Greater concentrations of chloride were found as a consequence of the partial sealing of the manure-soil interface. Surface runoff was the dominant process in the feedlot pen soil, whereas infiltration was the main process in control soil. Soil moisture flux beneath pens decreased substantially after 15 yr of activity. The estimated minimum leaching rate of chloride was 13 times faster than the estimated soil moisture flux. This difference suggests that chloride ions are not exclusively transported by advective flow under our conditions but also by solute diffusion and preferential flow. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  19. NERC's Biogeochemical Ocean Flux Study (North Atlantic Data Set) was collected aboard the RRS DISCOVERY and CHARLES DARWIN in the North Atlantic Ocean from 19890417 to 19910728 (NODC Accession 0000708)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Biogeochemical Ocean Flux Study (BOFS) was a Community Research Project of the Marine and Atmospheric Sciences Directorate of the Natural Environment Research...

  20. Flux quantisation in superconductivity rings and the mixed state

    International Nuclear Information System (INIS)

    Gough, C.E.

    1992-01-01

    This lecture introduces the concept of the macroscopic superconducting wave function and describes how this accounts for the Meissner Effect and flux quantisation. The experimental confirmation of flux quantisation in LTC, HTC and hybrid LTC/HTC rings will be briefly discussed. Flux quantisation in the superconducting mixed state leads to the formation of the Abrikosov flux in line lattice. Experiments confirming the flux line lattice in HTC superconductors by magnetic decoration and recent low angle neutron diffraction will be described. An extension of the mixed state model to granular superconductors with giant flux lines will also be briefly considered. (orig.)

  1. The limitation and modification of flux-limited diffusion theory

    International Nuclear Information System (INIS)

    Liu Chengan; Huang Wenkai

    1986-01-01

    The limitation of various typical flux-limited diffusion theory and advantages of asymptotic diffusion theory with time absorption constant are analyzed and compared. The conclusions are as following: Though the flux-limited problem in neutron diffusion theory are theoretically solved by derived flux-limited diffusion equation, it's going too far to limit flux due to the inappropriate assumption in deriving flux-limited diffusion equation. The asymptotic diffusion theory with time absorption constant has eliminated the above-mentioned limitation, and it is more accurate than flux-limited diffusion theory in describing neutron transport problem

  2. Science Shops

    DEFF Research Database (Denmark)

    Jørgensen, Michael Søgaard

    1999-01-01

    The paper prsents the overall concept of science shops as practised in most of the European science shops and present the concept practised and some experience obtained at the Technical University of Denmark. An outline for the planning of new sceince shops is presented.......The paper prsents the overall concept of science shops as practised in most of the European science shops and present the concept practised and some experience obtained at the Technical University of Denmark. An outline for the planning of new sceince shops is presented....

  3. Early results of experimental 222Rn flux campaign carried out at a mountain Spanish region and comparison with available radon flux inventories results

    Science.gov (United States)

    Nofuentes, Manel; Grossi, Claudia; Morguí, Josep Anton; Curcoll, Roger; Cañas, Lidia; Occhipinti, Paola; Borràs, Silvia; Vazquez, Eusebi; Rodó, Xavier

    2015-04-01

    The atmospheric concentrations of components impacting the greenhouse effect (CO2, CH4, N2O, O3, and aerosols) have increased significantly in the last two centuries, leading to a direct impact on our climate. These climatic changes deeply affect the geochemistry and the dynamics of the main reservoirs such as the atmosphere, the ocean, and the biosphere. Therefore, reductions of the emissions are needed for all four of the most important anthropogenic GHGs: CO2, CH4, N2O and SF6. Particularly, the relative contribution of human induced CH4 in the atmosphere to the total human direct greenhouse effect is about 25%. Furthermore, the CH4 has the shortest lifetime in the atmosphere (about 9 years), so that emissions reduction measures for CH4 will lead to changes in concentration growth rates, or even a concentration decline, at relatively shor time scales. All these reasons make the CH4 an attractive compound to reduce the greenhouse gas emissions. Nowadays, the study and attribution of categories for GHGs sources is carried out by using bottom-up inventories and top-down techniques. The atmospheric concentrations and the fluxes of the noble and radioactive 222Rn gas are widely used for retriving indirectly GHGs fluxes, improving top-down techniques and analysing different type of sources. In the frame of the "Methane exchange between soil and atmosphere over the Iberian Peninsula" (MIP) project (Reference: CGL2013-46186-R, Spanish Ministry of Economy and Competitiveness) four experimental radon flux campaigns are carried out at mountain as well as at coastal Spanish regions using integrated and continuous monitors. The early results of first radon flux campaign carried out at the Gredos and Iruelas climate station (GIC3) of the Catalan Institute of Climate Science (IC3) are presented and compared with available radon flux inventories maps.

  4. Inverse modeling of the terrestrial carbon flux in China with flux covariance among inverted regions

    Science.gov (United States)

    Wang, H.; Jiang, F.; Chen, J. M.; Ju, W.; Wang, H.

    2011-12-01

    Quantitative understanding of the role of ocean and terrestrial biosphere in the global carbon cycle, their response and feedback to climate change is required for the future projection of the global climate. China has the largest amount of anthropogenic CO2 emission, diverse terrestrial ecosystems and an unprecedented rate of urbanization. Thus information on spatial and temporal distributions of the terrestrial carbon flux in China is of great importance in understanding the global carbon cycle. We developed a nested inversion with focus in China. Based on Transcom 22 regions for the globe, we divide China and its neighboring countries into 17 regions, making 39 regions in total for the globe. A Bayesian synthesis inversion is made to estimate the terrestrial carbon flux based on GlobalView CO2 data. In the inversion, GEOS-Chem is used as the transport model to develop the transport matrix. A terrestrial ecosystem model named BEPS is used to produce the prior surface flux to constrain the inversion. However, the sparseness of available observation stations in Asia poses a challenge to the inversion for the 17 small regions. To obtain additional constraint on the inversion, a prior flux covariance matrix is constructed using the BEPS model through analyzing the correlation in the net carbon flux among regions under variable climate conditions. The use of the covariance among different regions in the inversion effectively extends the information content of CO2 observations to more regions. The carbon flux over the 39 land and ocean regions are inverted for the period from 2004 to 2009. In order to investigate the impact of introducing the covariance matrix with non-zero off-diagonal values to the inversion, the inverted terrestrial carbon flux over China is evaluated against ChinaFlux eddy-covariance observations after applying an upscaling methodology.

  5. Nitric oxide fluxes from an agricultural soil using a flux-gradient method

    Science.gov (United States)

    Taylor, N. M.; Wagner-Riddle, C.; Thurtell, G. W.; Beauchamp, E. G.

    1999-05-01

    Soil emission of nitric oxide may be a significant source of NOx in rural areas. Agricultural practices may enhance these emissions by addition of nitrogen fertilizers. A system that enables continuous measurement of NO fluxes from agricultural surfaces using the flux-gradient method was developed. Hourly differences in NO concentrations in air sampled at two intake heights (0.6 and 1 m) were determined using a chemiluminescence analyzer. Eddy diffusivities were determined using wind profiles (cup anemometers), and stability corrections calculated using a 5 cm path sonic anemometer. Fast switching of sampling between air intake heights (every 30 s) and determination of concentration values at a frequency of 2 Hz minimized the errors due to fluctuations in background concentration. Low travel times for air samples in the tubing (˜8 s) were estimated to result in small errors in flux values (chemical reactions. The overall resolution of the system was estimated as ˜1 ng N m-2s-1. NO fluxes from a bare soil were measured quasi-continuously from January to June 1995 at Elora, Canada, comprising a total of 1833 hourly values. Daily NO fluxes before nitrogen fertilization were small, increasing after nitrogen fertilizer was added (>10 ng N m-2 s-1). Monthly NO fluxes estimated were similar to those observed in previous studies. The designed system could be easily modified to measure NOx and NO fluxes by using an additional chemiluminescence analyzer. The system also could be adapted to measure fluxes sequentially from various plots, enabling testing of agricultural practices on NO emissions.

  6. Effect of chamber enclosure time on soil respiration flux: A comparison of linear and non-linear flux calculation methods

    DEFF Research Database (Denmark)

    Kandel, Tanka P; Lærke, Poul Erik; Elsgaard, Lars

    2016-01-01

    -deployment fluxes by linear regression techniques. Thus, usually the cumulative flux curve becomes downward concave due to the decreased gas diffusion rate. Non-linear models based on biophysical theory usually fit to such curvatures and may reduce the underestimation of fluxes. In this study, we examined...... the effect of increasing chamber enclosure time on SR flux rates calculated using a linear, an exponential and a revised Hutchinson and Mosier model (HMR). Soil respiration rates were measured with a closed chamber in combination with an infrared gas analyzer. During SR flux measurements the chamber......) to obtain a range of fluxes with different shapes of flux curves. The linear method provided more stable flux results during short enclosure times (few min) but underestimated initial fluxes by 15–300% after 45 min deployment time. Non-linear models reduced the underestimation as average underestimation...

  7. Regional nitrous oxide flux in Amazon basin

    International Nuclear Information System (INIS)

    Felippe, Monica Tais Siqueira D'Amelio

    2010-01-01

    Nitrous oxide (N 2 O) is the third most important anthropogenic greenhouse gas. Globally, the main sources of N 2 O are nitrification and denitrification in soils. About two thirds of the soil emissions occur in the tropics and approximately 20% originate in wet rain forest ecosystems, like the Amazon forest. The work presented here involves aircraft vertical profiles of N 2 O from the surface to 4 km over two sites in the Eastern and Central Amazon: Tapajos National Forest (2000-2009) and Cuieiras Biologic Reserve (2004-2007), and the estimation of N 2 O fluxes for regions upwind of these sites using two methods: Column Integration Technique and Inversion Model - FLEXPART. To our knowledge, these regional scale N 2 O measurements in Amazonia are unique and represent a new approach to looking regional scale emissions. For the both methods, the fluxes upwind of Cuieiras Biologic Reserve exhibited little seasonality, and the annual mean was 1.9 ±1.6 mgN 2 Om -2 day -1 for the Column Integration Technique and 2.3±0.9 mgN 2 Om -2 day -1 for Inversion Model - FLEXPART. For fluxes upwind of Tapajos Nacional Forest, the Inversion Model - FLEXPART presented about half (0.9±1.7 mgN 2 Om -2 day -1 ) of the Column Integration Technique (2.0±1.1 mgN 2 Om -2 day -1 ) for the same period (2004-2008). One reason could be because the inversion model does not consider anthropic activities, once it had a good representation for less impacted area. Both regions presented similar emission during wet season. By Column Integration Technique, fluxes upwind Tapajos Nacional Forest were similar for dry and wet seasons. The dry season N 2 O fluxes exhibit significant correlations with CO fluxes, indicating a larger than expected source of N 2 O from biomass burning. The average CO:N 2 O ratio for all 38 profiles sampled during the dry season was 82±69 mol CO:molN 2 O and suggests a larger biomass burning contribution to the global N 2 O budget than previously reported. (author)

  8. Gauge fluxes in F-theory compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Ling

    2016-07-13

    In this thesis, we study the geometry and physics of gauge fluxes in F-theory compactifications to four dimensions. Motivated by the phenomenological requirement of chiral matter in realistic model building scenarios, we develop methods for a systematic analysis of primary vertical G{sub 4}-fluxes on torus-fibred Calabi-Yau fourfolds. In particular, we extend the well-known description of fluxes on elliptic fibrations with sections to the more general set-up of genus-one fibrations with multi-sections. The latter are known to give rise to discrete abelian symmetries in F-theory. We test our proposal for constructing fluxes in such geometries on an explicit model with SU(5) x Z{sub 2} symmetry, which is connected to an ordinary elliptic fibration with SU(5) x U(1) symmetry by a conifold transition. With our methods we systematically verify anomaly cancellation and tadpole matching in both models. Along the way, we find a novel way of understanding anomaly cancellation in 4D F-theory in purely geometric terms. This observation is further strengthened by a similar analysis of an SU(3) x SU(2) x U(1){sup 2} model. The obvious connection of this particular model with the Standard Model is then investigated in a more phenomenologically motivated survey. There, we will first provide possible matchings of the geometric spectrum with the Standard Model states, which highlights the role of the additional U(1) factor as a selection rule. In a second step, we then utilise our novel methods on flux computations to set up a search algorithm for semi-realistic chiral spectra in our Standard- Model-like fibrations over specific base manifolds B. As a demonstration, we scan over three choices P{sup 3}, Bl{sub 1}P{sup 3} and Bl{sub 2}P{sup 3} for the base. As a result we find a consistent flux that gives the chiral Standard Model spectrum with a vector-like triplet exotic, which may be lifted by a Higgs mechanism.

  9. Effects of quartz on crystallization behavior of mold fluxes and microstructural characteristics of flux film.

    Science.gov (United States)

    Lei, Liu; Xiuli, Han; Mingduo, Li; Di, Zhang

    2018-01-01

    Mold fluxes are mainly prepared using cement clinker, quartz, wollastonite, borax, fluorite, soda ash and other mineral materials. Quartz, as one of the most common and essential materials, was chosen for this study to analyze itseffects on crystallization temperature, critical cooling rate, crystal incubation time, crystallization ratio and phases of flux film. We used the research methods of process mineralogy with the application of the single hot thermocouple technique, heat flux simulator, polarizing microscope, X-ray diffraction, etc. Results: By increasing the quartz content from 16 mass% to 24 mass%, the crystallization temperature, critical cooling rate and crystallization ratio of flux film decreased, and the crystal incubation time was extended. Meanwhile, the mineralogical structure of the flux film changed, with a large amount of wollastonite precipitation and a significant decrease in the cuspidine content until it reached zero. This showed a steady decline in the heat transfer control capacity of the flux film. The reason for the results above is that, by increasing the quartz content, the silicon-oxygen tetrahedron network structure promoted a rise in viscosity and restrained ion migration, inhibiting crystal nucleation and growth, leading to the weakening of the crystallization and a decline in the crystallization ratio.

  10. Comparison between elementary flux modes analysis and 13C-metabolic fluxes measured in bacterial and plant cells.

    Science.gov (United States)

    Beurton-Aimar, Marie; Beauvoit, Bertrand; Monier, Antoine; Vallée, François; Dieuaide-Noubhani, Martine; Colombié, Sophie

    2011-06-20

    (13)C metabolic flux analysis is one of the pertinent ways to compare two or more physiological states. From a more theoretical standpoint, the structural properties of metabolic networks can be analysed to explore feasible metabolic behaviours and to define the boundaries of steady state flux distributions. Elementary flux mode analysis is one of the most efficient methods for performing this analysis. In this context, recent approaches have tended to compare experimental flux measurements with topological network analysis. Metabolic networks describing the main pathways of central carbon metabolism were set up for a bacteria species (Corynebacterium glutamicum) and a plant species (Brassica napus) for which experimental flux maps were available. The structural properties of each network were then studied using the concept of elementary flux modes. To do this, coefficients of flux efficiency were calculated for each reaction within the networks by using selected sets of elementary flux modes. Then the relative differences - reflecting the change of substrate i.e. a sugar source for C. glutamicum and a nitrogen source for B. napus - of both flux efficiency and flux measured experimentally were compared. For both organisms, there is a clear relationship between these parameters, thus indicating that the network structure described by the elementary flux modes had captured a significant part of the metabolic activity in both biological systems. In B. napus, the extension of the elementary flux mode analysis to an enlarged metabolic network still resulted in a clear relationship between the change in the coefficients and that of the measured fluxes. Nevertheless, the limitations of the method to fit some particular fluxes are discussed. This consistency between EFM analysis and experimental flux measurements, validated on two metabolic systems allows us to conclude that elementary flux mode analysis could be a useful tool to complement (13)C metabolic flux analysis

  11. Science Fairs for Science Literacy

    Science.gov (United States)

    Mackey, K. R.

    2014-12-01

    Science literacy is imperative for well informed civic and personal decision making, yet only a quarter of American adults are proficient enough in science to understand science stories reported in the popular press. Hands-on research increases confidence in and understanding of science. When guiding students in designing and conducting science fair projects, mentors can foster science literacy by helping students focus on three goals: (1) articulating hypotheses or questions, (2) designing feasible projects, and (3) learning to make and interpret graphs. These objectives introduce students to the methodological nature of scientific research and give them the tools to interpret scientific facts and data in order to make informed decisions for themselves and society.

  12. Advances in nuclear science and technology

    CERN Document Server

    Henley, Ernest J

    1970-01-01

    Advances in Nuclear Science and Technology, Volume 5 presents the underlying principles and theory, as well as the practical applications of the advances in the nuclear field. This book reviews the specialized applications to such fields as space propulsion.Organized into six chapters, this volume begins with an overview of the design and objective of the Fast Flux Test Facility to provide fast flux irradiation testing facilities. This text then examines the problem in the design of nuclear reactors, which is the analysis of the spatial and temporal behavior of the neutron and temperature dist

  13. The science in social science.

    Science.gov (United States)

    Bernard, H Russell

    2012-12-18

    A recent poll showed that most people think of science as technology and engineering--life-saving drugs, computers, space exploration, and so on. This was, in fact, the promise of the founders of modern science in the 17th century. It is less commonly understood that social and behavioral sciences have also produced technologies and engineering that dominate our everyday lives. These include polling, marketing, management, insurance, and public health programs.

  14. Lepton fluxes from atmospheric charm revisited

    International Nuclear Information System (INIS)

    Garzelli, M.V.; Moch, S.; Sigl, G.

    2015-07-01

    We update predictions for lepton fluxes from the hadroproduction of charm quarks in the scattering of primary cosmic rays with the Earth's atmosphere. The calculation of charm-pair hadroproduction applies the latest results from perturbative QCD through next-to-next-to-leading order and modern parton distributions, together with estimates on various sources of uncertainties. Our predictions for the lepton fluxes turn out to be compatible, within the uncertainty band, with recent results in the literature. However, by taking into account contributions neglected in previous works, our total uncertainties are much larger. The predictions are crucial for the interpretation of results from neutrino experiments like IceCube, when disentangling signals of neutrinos of astrophysical origin from the atmospheric background.

  15. Observations on fluxes near anti-branes

    Energy Technology Data Exchange (ETDEWEB)

    Cohen-Maldonado, Diego [Institute of Physics, University of Amsterdam, Science Park,Postbus 94485, Amsterdam, 1090 GL The (Netherlands); Diaz, Juan; Riet, Thomas Van [Instituut voor Theoretische Fysica, K.University Leuven,Celestijnenlaan 200D, Leuven, B-3001 (Belgium); Vercnocke, Bert [Institute of Physics, University of Amsterdam, Science Park,Postbus 94485, Amsterdam, 1090 GL The (Netherlands)

    2016-01-20

    We revisit necessary conditions for gluing local (anti-)D3 throats into flux throats with opposite charge. These consistency conditions typically reveal singularities in the 3-form fluxes whose meaning is being debated. In this note we prove, under well-motivated assumptions, that unphysical singularities can potentially be avoided when the anti-branes polarise into spherical NS5 branes, with a specific radius. If a consistent solution can then indeed be found, our analysis seems to suggests a rather large correction to the radius of the polarization sphere compared to the probe result. We furthermore comment on the gluing conditions at finite temperature and point out that one specific assumption of a recent no-go theorem can be broken if anti-branes are indeed to polarise into spherical NS5 branes at zero temperature.

  16. Earth-like sand fluxes on Mars.

    Science.gov (United States)

    Bridges, N T; Ayoub, F; Avouac, J-P; Leprince, S; Lucas, A; Mattson, S

    2012-05-09

    Strong and sustained winds on Mars have been considered rare, on the basis of surface meteorology measurements and global circulation models, raising the question of whether the abundant dunes and evidence for wind erosion seen on the planet are a current process. Recent studies showed sand activity, but could not determine whether entire dunes were moving--implying large sand fluxes--or whether more localized and surficial changes had occurred. Here we present measurements of the migration rate of sand ripples and dune lee fronts at the Nili Patera dune field. We show that the dunes are near steady state, with their entire volumes composed of mobile sand. The dunes have unexpectedly high sand fluxes, similar, for example, to those in Victoria Valley, Antarctica, implying that rates of landscape modification on Mars and Earth are similar.

  17. Helium cosmic ray flux measurements at Mars

    International Nuclear Information System (INIS)

    Lee, Kerry; Pinsky, Lawrence; Andersen, Vic; Zeitlin, Cary; Cleghorn, Tim; Cucinotta, Frank; Saganti, Premkumar; Atwell, William; Turner, Ron

    2006-01-01

    The helium energy spectrum in Martian orbit has been observed by the MARIE charged particle spectrometer aboard the 2001 Mars Odyssey spacecraft. The orbital data were taken from March 13, 2002 to October 28, 2003, at which time a very intense Solar Particle Event caused a loss of communication between the instrument and the spacecraft. The silicon detector stack in MARIE is optimized for the detection of protons and helium in the energy range below 100MeV/n, which typically includes almost all of the flux during SPEs. This also makes MARIE an efficient detector for GCR helium in the energy range of 50-150MeV/n. We will present the first fully normalized flux results from MARIE, using helium ions in this energy range

  18. Reduced TCA Flux in Diabetic Myotubes

    DEFF Research Database (Denmark)

    Gaster, Michael

    2012-01-01

    The diabetic phenotype is complex, requiring elucidation of key initiating defects. Diabetic myotubes express a primary reduced tricarboxylic acid (TCA) cycle flux but at present it is unclear in which part of the TCA cycle the defect is localised. In order to localise the defect we studied ATP...... production in isolated mitochondria from substrates entering the TCA cycle at various points. ATP production was measured by luminescence with or without concomitant ATP utilisation by hexokinase in mitochondria isolated from myotubes established from eight lean and eight type 2 diabetic subjects. The ATP......, there was no significant difference between groups. These results show that the primary reduced TCA cycle flux in diabetic myotubes is not explained by defects in specific part of the TCA cycle but rather results from a general downregulation of the TCA cycle....

  19. Anthropogenic methane ebullition and continuous flux measurement

    Science.gov (United States)

    Alshboul, Zeyad

    2017-04-01

    Keywords: Methane, Wastewater, Effluent, Anaerobic treatment. Municipal wastewater treatment plants (WWTPs) have shown to emit significant amount of methane during treatment processes. While most of studies cover only in-plant diffusive methane flux, magnitude and sources of methane ebullition have not well assessed. Moreover, the reported results of methane emissions from WWTPs are based on low spatial and temporal resolution. Using a continuous measurement approach of methane flux rate for effluent system and secondary clarifier treatment process at one WWTP in Southwest Germany, our results show that high percentage of methane is emitted by ebullition during the anaerobic treatment (clarification pond) with high spatial and temporal variability. Our measurements revealed that no ebullition is occur at the effluent system. The observed high contribution of methane ebullition to the total in-plant methane emission, emphasizes the need for considering in-plant methane emission by ebullition as well as the spatial and temporal variability of these emissions.

  20. Flux Limiter Lattice Boltzmann for Compressible Flows

    International Nuclear Information System (INIS)

    Chen Feng; Li Yingjun; Xu Aiguo; Zhang Guangcai

    2011-01-01

    In this paper, a new flux limiter scheme with the splitting technique is successfully incorporated into a multiple-relaxation-time lattice Boltzmann (LB) model for shacked compressible flows. The proposed flux limiter scheme is efficient in decreasing the artificial oscillations and numerical diffusion around the interface. Due to the kinetic nature, some interface problems being difficult to handle at the macroscopic level can be modeled more naturally through the LB method. Numerical simulations for the Richtmyer-Meshkov instability show that with the new model the computed interfaces are smoother and more consistent with physical analysis. The growth rates of bubble and spike present a satisfying agreement with the theoretical predictions and other numerical simulations. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  1. Flux qubit to a transmission line

    Energy Technology Data Exchange (ETDEWEB)

    Haeberlein, Max; Baust, Alexander; Zhong, Ling; Gross, Rudolf [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Physik-Department, TU Muenchen, Garching (Germany); Nanosystems Initiative Munich (NIM), Muenchen (Germany); Anderson, Gustav; Wang, Lujun; Eder, Peter; Fischer, Michael; Goetz, Jan; Xie, Edwar; Schwarz, Manuel; Wulschner, Karl Friedrich; Deppe, Frank; Fedorov, Kirill; Huebl, Hans; Menzel, Edwin [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Physik-Department, TU Muenchen, Garching (Germany); Marx, Achim [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany)

    2015-07-01

    Within the last decade, superconducting qubits coupled to microwave resonators have been extensively studied within the framework of quantum electrodynamics. Ultimately, quantum computing seems within reach in such architectures. However, error correction schemes are necessary to achieve the required fidelity in multi-qubit operations, drastically increasing the number of qubits involved. In this work, we couple a flux qubit to a transmission line where it interacts with itinerant microwave photons granting access to all-optical quantum computing. In this approach, travelling photons generate entanglement between two waveguides, containing the qubit information. In this presentation, we show experimental data on flux qubits coupled to transmission lines. Furthermore, we will discuss entanglement generation between two separate paths.

  2. Chiral charge flux and electroweak baryogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Funakubo, Koichi [Saga Univ. (Japan). Dept. of Physics; Kakuto, Akira; Otsuki, Shoichiro; Takenaga, Kazunori; Toyoda, Fumihiko

    1995-06-01

    By treating CP-violating interaction of the electroweak bubble wall as a perturbative term, chiral charge flux through the bubble wall is estimated. It is found that the absolute value of the flux F{sub Q} has a sharp peak at m{sub 0} - a - T with F{sub Q}/(uT{sup 3}) - 10{sup -3}(Q{sub L}-Q{sub R}){Delta}{theta}. Here m{sub 0} is the fermion mass, 1/a is the wall thickness, T is the temperature at which the bubbles are growing, u is the wall velocity, Q{sub L(R)} is the chiral charge of the relevant left (right)-handed fermion and {Delta}{theta} is the measure of CP violation. (author).

  3. The sciences of science communication.

    Science.gov (United States)

    Fischhoff, Baruch

    2013-08-20

    The May 2012 Sackler Colloquium on "The Science of Science Communication" brought together scientists with research to communicate and scientists whose research could facilitate that communication. The latter include decision scientists who can identify the scientific results that an audience needs to know, from among all of the scientific results that it would be nice to know; behavioral scientists who can design ways to convey those results and then evaluate the success of those attempts; and social scientists who can create the channels needed for trustworthy communications. This overview offers an introduction to these communication sciences and their roles in science-based communication programs.

  4. Data system for automatic flux mapping applications

    International Nuclear Information System (INIS)

    Oates, R.M.; Neuner, J.A.; Couch, R.D. Jr.; Kasinoff, A.M.

    1982-01-01

    This patent discloses interface circuitry for coupling the data from neutron flux detectors in a reactor core to microprocessors. This circuitry minimizes the microprocessor time required to accept data and provides a technique for measuring variable frequency data from the in-core detectors within a minimum amount of hardware and with crystal-controlled accuracy. A frequency link is employed to transmit data with good isolation, and the information is measured using a programmable timer

  5. 2 π gaseous flux proportional detector

    International Nuclear Information System (INIS)

    Guevara, E.A.; Costello, E.D.; Di Carlo, R.O.

    1986-01-01

    A counting system has been developed in order to measure carbon-14 samples obtained in the course of a study of a plasmapheresis treatment for diabetic children. The system is based on the use of a 2π gaseous flux proportional detector especially designed for the stated purpose. The detector is described and experiment results are given, determining the characteristic parameters which set up the working conditions. (Author) [es

  6. Periods of High Intensity Solar Proton Flux

    Science.gov (United States)

    Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Thomas M.; Adams, James H.; Dietrich, William F.

    2012-01-01

    Analysis is presented for times during a space mission that specified solar proton flux levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar cycle are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models.

  7. The cosmic ray muon flux at WIPP

    Energy Technology Data Exchange (ETDEWEB)

    Esch, E.-I. [Los Alamos National Laboratory, LANSCE-3, MS H855, Los Alamos, NM 87545 (United States) and II. Physikalisches Institut, Justus Liebig Univeritaet Giessen, Giessen (Germany)]. E-mail: ernst@lanl.gov; Bowles, T.J [Los Alamos National Laboratory, LANSCE-3, MS H855, Los Alamos, NM 87545 (United States); Hime, A. [Los Alamos National Laboratory, LANSCE-3, MS H855, Los Alamos, NM 87545 (United States); Pichlmaier, A. [Los Alamos National Laboratory, LANSCE-3, MS H855, Los Alamos, NM 87545 (United States); Reifarth, R. [Los Alamos National Laboratory, LANSCE-3, MS H855, Los Alamos, NM 87545 (United States); Wollnik, H. [II. Physikalisches Institut, Justus Liebig Univeritaet Giessen, Giessen (Germany)

    2005-02-11

    In this work, a measurement of the muon intensity at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM, USA is presented. WIPP is a salt mine with a depth of 655m. The vertical muon flux was measured with a two panel scintillator coincidence setup to {phi}{sub vert}=(3.10{sub -0.07}{sup +0.05})10{sup -7}s{sup -1}cm{sup -}2sr{sup -1}.

  8. Axial flux permanent magnet brushless machines

    CERN Document Server

    Gieras, Jacek F; Kamper, Maarten J

    2008-01-01

    Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators

  9. FAST FLUX TEST FACILITY DRIVER FUEL MEETING

    Energy Technology Data Exchange (ETDEWEB)

    None,

    1966-06-01

    The Pacific Northwest Laboratory has convened this meeting to enlist the best talents of our laboratories and industry in soliciting factual, technical information pertinent to the Pacific Northwest's Laboratory's evaluation of the potential fuel systems for the Fast Flux Test Facility. The particular factors emphasized for these fuel systems are those associated with safety, ability to meet testing objectives, and economics. The proceedings includes twenty-three presentations, along with a transcript of the discussion following each, as well as a summary discussion.

  10. Integrated Science.

    Science.gov (United States)

    Rainey, Larry; Miller, Roxanne Greitz

    1997-01-01

    Describes the Integrated Science program that integrates biology, earth/space science, chemistry, and physics over a three-year, spiraling sequence arranged around broad themes such as cycles, changes, patterns, and waves. Includes weekly telecasts via public television and satellite, teacher manuals, student handbooks, e-mail connections, staff…

  11. Using Science

    Science.gov (United States)

    Kelly, Deryk

    1971-01-01

    Article discusses educational benefits of science hobbies, citing specific accomplishments of British students. New courses in Engineering Science and recent development of scientific investigation and technological classroom projects are noted. Author relates how students have solved specific practical problems, such as devising games to develop…

  12. Life sciences

    International Nuclear Information System (INIS)

    Day, L.

    1991-04-01

    This document is the 1989--1990 Annual Report for the Life Sciences Divisions of the University of California/Lawrence Berkeley Laboratory. Specific progress reports are included for the Cell and Molecular Biology Division, the Research Medicine and Radiation Biophysics Division (including the Advanced Light Source Life Sciences Center), and the Chemical Biodynamics Division. 450 refs., 46 figs

  13. Life sciences

    Energy Technology Data Exchange (ETDEWEB)

    Day, L. (ed.)

    1991-04-01

    This document is the 1989--1990 Annual Report for the Life Sciences Divisions of the University of California/Lawrence Berkeley Laboratory. Specific progress reports are included for the Cell and Molecular Biology Division, the Research Medicine and Radiation Biophysics Division (including the Advanced Light Source Life Sciences Center), and the Chemical Biodynamics Division. 450 refs., 46 figs. (MHB)

  14. Science Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 2. Science Matters A Book for Curious Minds. Rohini Godbole. Book Review Volume 2 Issue 2 February 1997 pp 94-95. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/002/02/0094-0095 ...

  15. Greenhouse gas flux dynamics in wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Silvola, J.; Alm, J.; Saarnio, S. [Joensuu Univ. (Finland). Dept. of Biology; Martikainen, P.J. [National Public Health Inst., Kuopio (Finland). Dept. of Environmental Microbiology

    1996-12-31

    Two important greenhouse gases, CO{sub 2} and CH{sub 4}, are closely connected to the carbon cycling of wetlands. Although virgin wetlands are mostly carbon accumulating ecosystems, major proportion of the CO{sub 2} bound annually in photosynthesis is released back to the atmosphere. Main portion of the carbon cycling in wetlands is quite fast while a small proportion of carbon diffusing from soil is released from organic matter, which may be ten thousand years old. Methane is formed in the anaerobic layers of wetlands, from where it is released gradually to the atmosphere. The decomposition in anaerobic conditions is very slow, which means that usually only a few percent of the annual carbon cycling takes place as methane. Research on CO{sub 2} fluxes of different virgin and managed peatlands was the main topic of this project during the first phase of SILMU. The measurements were made during two seasons in varying conditions in c. 30 study sites. In the second phase of SILMU the research topics were the spatial and temporal variation of CO{sub 2} and CH{sub 4} fluxes, the relationships between vegetation and gas fluxes as well as carbon balance studies in wetlands at some intensive sites

  16. Small scale magnetic flux-averaged magnetohydrodynamics

    International Nuclear Information System (INIS)

    Pfirsch, D.; Sudan, R.N.

    1994-01-01

    By relaxing exact magnetic flux conservation below a scale λ a system of flux-averaged magnetohydrodynamic equations are derived from Hamilton's principle with modified constraints. An energy principle can be derived from the linearized averaged system because the total system energy is conserved. This energy principle is employed to treat the resistive tearing instability and the exact growth rate is recovered when λ is identified with the resistive skin depth. A necessary and sufficient stability criteria of the tearing instability with line tying at the ends for solar coronal loops is also obtained. The method is extended to both spatial and temporal averaging in Hamilton's principle. The resulting system of equations not only allows flux reconnection but introduces irreversibility for appropriate choice of the averaging function. Except for boundary contributions which are modified by the time averaging process total energy and momentum are conserved over times much longer than the averaging time τ but not for less than τ. These modified boundary contributions correspond to the existence, also, of damped waves and shock waves in this theory. Time and space averaging is applied to electron magnetohydrodynamics and in one-dimensional geometry predicts solitons and shocks in different limits

  17. High heat flux device of thermonuclear device

    International Nuclear Information System (INIS)

    Tachikawa, Nobuo.

    1994-01-01

    The present invention provides an equipments for high heat flux device (divertor) of a thermonuclear device, which absorbs thermal deformation during operation, has a high installation accuracy, and sufficiently withstands for thermal stresses. Namely, a heat sink member is joined to a structural base. Armour tiles are joined on the heat sink member. Cooling pipes are disposed between the heat sink member and the armour tiles. With such a constitution, the heat sink member using a highly heat conductive material having ductility, such as oxygen free copper, the cooling pipes using a material having excellent high temperature resistance and excellent elongation, such as aluminum-dispersed reinforced copper, and the armour tiles are completely joined on the structural base. Therefore, when thermal deformation tends to cause in the high heat flux device such as a divertor, cooling pipes cause no plastic deformation because of their high temperature resistance, but the heat sink member such as a oxygen free copper causes plastic deformation to absorb thermal deformation. As a result, the high heat flux device such as a divertor causes no deformation. (I.S.)

  18. Are Quasar Jets Dominated by Poynting Flux?

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, M

    2005-02-02

    The formation of relativistic astrophysical jets is presumably mediated by magnetic fields threading accretion disks and central, rapidly rotating objects. As it is accelerated by magnetic stresses, the jet's kinetic energy flux grows at the expense of its Poynting flux. However, it is unclear how efficient is the conversion from magnetic to kinetic energy and whether there are any observational signatures of this process. We address this issue in the context of jets in quasars. Using data from all spatial scales, we demonstrate that in these objects the conversion from Poynting-flux-dominated to matter-dominated jets is very likely to take place closer to the black hole than the region where most of the Doppler boosted radiation observed in blazars is produced. We briefly discuss the possibility that blazar activity can be induced by global MHD instabilities, e.g., via the production of localized velocity gradients that lead to dissipative events such as shocks or magnetic reconnection, where acceleration of relativistic particles and production of non-thermal flares is taking place.

  19. Burnout heat flux in natural flow boiling

    International Nuclear Information System (INIS)

    Helal, M.M.; Darwish, M.A.; Mahmoud, S.I.

    1978-01-01

    Twenty runs of experiments were conducted to determine the critical heat flux for natural flow boiling with water flowing upwards through annuli of centrally heated stainless steel tube. The test section has concentric heated tube of 14mm diameter and heated lengthes of 15 and 25 cm. The outside surface of the annulus was formed by various glass tubes of 17.25, 20 and 25.9mm diameter. System pressure is atmospheric. Inlet subcooling varied from 18 to 5 0 C. Obtained critical heat flux varied from 24.46 to 62.9 watts/cm 2 . A number of parameters having dominant influence on the critical heat flux and hydrodynamic instability (flow and pressure oscillations) preceeding the burnout have been studied. These parameters are mass flow rate, mass velocity, throttling, channel geometry (diameters ratio, length to diameter ratio, and test section length), and inlet subcooling. Flow regimes before and at the moments of burnout were observed, discussed, and compared with the existing physical model of burnout

  20. GALILEO PROBE NET FLUX RADIOMETER DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Galileo Probe Net Flux Radiometer (NFR) measured net and upward radiation fluxes in Jupiter's atmosphere between about 0.44 bars and 14 bars, using five spectral...

  1. NAMMA SENEGAL RADIOSONDE AND TOWER FLUX DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA Senegal Radiosonde and Tower Flux data includes measurements of humidity, wind speed/direction and velocity. Additionally, the flux data includes...

  2. Advanced Tethersonde for High-Speed Flux Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Flux measurements of trace gases and other quantities, such as latent heat, are of great importance in scientific field research. One typical flux measurement setup...

  3. Advanced Tethersonde for High-Speed Flux Measurements, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Flux measurements of trace gases and other quantities, such as latent heat, are of great importance in scientific field research. One typical flux measurement setup...

  4. Physics of magnetic flux ropes. Geophysical Monograph, No. 58

    International Nuclear Information System (INIS)

    Russell, C.T.; Priest, E.R.; Lee, L.C.

    1990-01-01

    The present work encompasses papers on the structure, waves, and instabilities of magnetic flux ropes (MFRs), photospheric flux tubes (PFTs), the structure and heating of coronal loops, solar prominences, coronal mass ejections and magnetic clouds, flux ropes in planetary ionospheres, the magnetopause, magnetospheric field-aligned currents and flux tubes, and the magnetotail. Attention is given to the equilibrium of MFRs, resistive instability, magnetic reconnection and turbulence in current sheets, dynamical effects and energy transport in intense flux tubes, waves in solar PFTs, twisted flux ropes in the solar corona, an electrodynamical model of solar flares, filament cooling and condensation in a sheared magnetic field, the magnetopause, the generation of twisted MFRs during magnetic reconnection, ionospheric flux ropes above the South Pole, substorms and MFR structures, evidence for flux ropes in the earth magnetotail, and MFRs in 3D MHD simulations

  5. Electronic Reliability and the Environmental Thermal Neutron Flux

    National Research Council Canada - National Science Library

    Clark, John

    2002-01-01

    .... The goal of this project is to characterize the environmental thermal neutron flux with respect to electronic reliability by performing measurements of the thermal neutron flux in various locations...

  6. NAMMA SENEGAL RADIOSONDE AND TOWER FLUX DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA Senegal Radiosonde and Tower Flux data includes measurements of humidity, wind speed/direction and velocity. Additionally the Flux data includes...

  7. Direct Torque Control Induction Motor Drive with Improved Flux Response

    Directory of Open Access Journals (Sweden)

    Bhoopendra Singh

    2012-01-01

    Full Text Available Accurate flux estimation and control of stator flux by the flux control loop is the determining factor in effective implementation of DTC algorithm. In this paper a comparison of voltage-model-based flux estimation techniques for flux response improvement is carried out. The effectiveness of these methods is judged on the basis of Root Mean Square Flux Error (RMSFE, Total Harmonic Distortion (THD of stator current, and dynamic flux response. The theoretical aspects of these methods are discussed and a comparative analysis is provided with emphasis on digital signal processor (DSP based controller implementation. The effectiveness of the proposed flux estimation algorithm is investigated through simulation and experimentally validated on a test drive.

  8. Metabolite Depletion Affects Flux Profiling of Cell Lines

    DEFF Research Database (Denmark)

    Nilsson, A.; Haanstra, J. R.; Teusink, B.

    2018-01-01

    Quantifying the rate of consumption and release of metabolites (i.e., flux profiling) has become integral to the study of cancer. The fluxes as well as the growth of the cells may be affected by metabolite depletion during cultivation.......Quantifying the rate of consumption and release of metabolites (i.e., flux profiling) has become integral to the study of cancer. The fluxes as well as the growth of the cells may be affected by metabolite depletion during cultivation....

  9. Measurements of neutron flux in the RA reactor

    International Nuclear Information System (INIS)

    Raisic, N.

    1961-12-01

    This report includes the following separate parts: Thermal neutron flux in the experimental channels od RA reactor; Epithermal neutron flux in the experimental channels od RA reactor; Fast neutron flux in the experimental channels od RA reactor; Thermal neutron flux in the thermal column and biological experimental channel; Neutronic measurements in the RA reactor cell; Temperature reactivity coefficient of the RA reactor; design of the device for measuring the activity of wire [sr

  10. Aspects of six-dimensional flux compactifications

    International Nuclear Information System (INIS)

    Dierigl, Markus

    2017-08-01

    In this thesis we investigate various aspects of flux compactifications in six-dimensional quantum field theories. After introducing the internal geometries, i.e. the two-dimensional torus T 2 and one of its orbifolds T 2 /Z 2 , we classify possible gauge backgrounds including continuous and discrete Wilson lines with emphasis on a non-vanishing flux density. An operator analogy with the quantum harmonic oscillator allows for an explicit derivation of the mode functions of charged fields and demonstrates the advantage of our interpretation of discrete Wilson lines in terms of localized fractional gauge fluxes. We then derive a globally supersymmetric action which captures the D-term supersymmetry breaking induced by the internal magnetic field and reproduces the Landau level mass spectrum of the charged four-dimensional degrees of freedom. In this context we show that, even though supersymmetry is broken at the compactification scale, the inclusion of the whole tower of charged states leads to vanishing quantum corrections for the Wilson line effective potential on T 2 . This result is supported by a symmetry breaking argument in which the Wilson line appears as a Goldstone boson. After that, we additionally include gravitational effects within a supergravity effective action of the lightest modes in four dimensions. The dynamics of the moduli fields arising after compactification can be encoded in the setup of N=1 supergravity augmented with anomaly cancellation by the Green-Schwarz mechanism. This leads to a non-trivial transformation behavior for two axion fields under gauge variations in the low-energy effective action. As an application, we discuss an SO(10) x U(1) grand unified theory which uses the multiplicity of fermionic zero modes in the flux background to induce the number of matter generations. Finally, we investigate a novel mechanism for generating de Sitter vacua in N=1 supergravity based on a flux-induced positive definite D-term potential. The

  11. Boosted Fast Flux Loop Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Boosted Fast Flux Loop Project Staff

    2009-09-01

    The Boosted Fast Flux Loop (BFFL) project was initiated to determine basic feasibility of designing, constructing, and installing in a host irradiation facility, an experimental vehicle that can replicate with reasonable fidelity the fast-flux test environment needed for fuels and materials irradiation testing for advanced reactor concepts. Originally called the Gas Test Loop (GTL) project, the activity included (1) determination of requirements that must be met for the GTL to be responsive to potential users, (2) a survey of nuclear facilities that may successfully host the GTL, (3) conceptualizing designs for hardware that can support the needed environments for neutron flux intensity and energy spectrum, atmosphere, flow, etc. needed by the experimenters, and (4) examining other aspects of such a system, such as waste generation and disposal, environmental concerns, needs for additional infrastructure, and requirements for interfacing with the host facility. A revised project plan included requesting an interim decision, termed CD-1A, that had objectives of' establishing the site for the project at the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL), deferring the CD 1 application, and authorizing a research program that would resolve the most pressing technical questions regarding GTL feasibility, including issues relating to the use of booster fuel in the ATR. Major research tasks were (1) hydraulic testing to establish flow conditions through the booster fuel, (2) mini-plate irradiation tests and post-irradiation examination to alleviate concerns over corrosion at the high heat fluxes planned, (3) development and demonstration of booster fuel fabrication techniques, and (4) a review of the impact of the GTL on the ATR safety basis. A revised cooling concept for the apparatus was conceptualized, which resulted in renaming the project to the BFFL. Before the subsequent CD-1 approval request could be made, a decision was made in April

  12. Application of sensitive and supersensitive radon detectors for radon flux density and radon concentration in environmental monitoring

    International Nuclear Information System (INIS)

    Zahorowski, W.; Whittlestone, S.

    1997-01-01

    The paper presents a review of principles and operational parameters of the latest instrumental development in sensitive and high sensitive radon detectors at Australian Nuclear Science and Technology Organisation (ANSTO). The focus is on advances in measurement technology of radon concentration in air and radon flux density. Two areas in which ANSTO is actively involved are discussed. The first area concerns radon in air monitoring at Cape Grim Baseline Air Pollution Station. Results recorded at the Station with a supersensitive radon detector characterised by lower limit of detection down to few mBq m -3 with time resolution better than 90 minutes are presented to illustrate importance of the technique in global monitoring of airborne pollution. The second area concerns estimates of radon and thoron fluxes from large geographical areas. This is illustrated by results obtained during an Australia-wide survey of radon fluxes and from thoron flux measurements around the Mauna Loa Observatory in Hawaii. The radon flux estimates from Australia come from a coarse net of spot measurements combined with data from aerial gamma surveys. It is argued that as radon global flux and air concentration estimates improve, the data will provide progressively more stringent tests of global air transport models. (author)

  13. Propagation of monopole defects and flux channels in an artificial square spin-ice lattice

    Science.gov (United States)

    Zhu, Yimei; Volkov, V. V.; Pollard, Shawn

    2012-02-01

    The recent development of artificial lattices of magnetic islands in which competing interactions give rise to macroscopic analogs of atomically frustrated spin ices has opened up a new field of research, in which the interaction, frustration and evolution of individual magnetic elements can be directly observed in real space. We investigate the magnetic reversal along the (11) symmetry axis of permalloy islands in an artificial ``square'' spin-ice geometry with in-situ Lorentz transmission electron microscopy. Novel differential transport-of-intensity allows for the identification of ``monopole''-like defects and flux channels, similar to Dirac strings, that link them. We track the growth and propagation of these defects and flux channels throughout the reversal process. Simulations are used to compare with experiment to show how nucleation and propagation of defects affect the reversal of the lattice as a whole. We find that interactions between defects and flux channels can explain the saturation of defect populations at low net magnetizations. This work was supported by U.S. Department of Energy, Office of Basic Energy Science, Material Sciences and Engineering Division, under Contract No. DE-AC02-98CH10886.

  14. The measurements of thermal neutron flux distribution in a paraffin

    Indian Academy of Sciences (India)

    The term `thermal flux' implies a Maxwellian distribution of velocity and energy corresponding to the most probable velocity of 2200 ms-1 at 293.4 K. In order to measure the thermal neutron flux density, the foil activation method was used. Thermal neutron flux determination in paraffin phantom by counting the emitted rays of ...

  15. An alternative method for the measurement of neutron flux

    Indian Academy of Sciences (India)

    Here, the neutron flux inferred from the neutron count rate obtained with R-12 SDD shows an excellent agreement with the flux inferred from the neutron dose rate in a non-dissipative medium. Keywords. Neutron dose; neutron flux; superheated droplet detector; bubble nucleation. PACS Nos 29.40.Rg; 29.40.–n; 29.25.Dz. 1.

  16. Interrelationship between cloud cover and sensible heat flux over ...

    Indian Academy of Sciences (India)

    higher (lower) magnitudes of these fluxes in dry. (moist) convective sector. However, these fluxes when day-time averaged, were found to bear no sig- nificant relationship with evening cloud cover. Such negative relationship between sensible heat fluxes (SHF) and total cloud cover (TCC) appears to be contradictory to the ...

  17. Soil heat flux and day time surface energy balance closure

    Indian Academy of Sciences (India)

    Soil heat flux is an important input component of surface energy balance. Estimates of soil heat flux were made in the year 2008 using soil temperature data at Astronomical Observatory, Thiruvananthapuram, south Kerala. Hourly values of soil heat flux from 00 to 24 LST are presented for selected days typical of the winter, ...

  18. Measurements of carbon dioxide and heat fluxes during monsoon ...

    Indian Academy of Sciences (India)

    Using these observations, we explored the diurnal variability of CO2 flux along with sensible and latent heat. The CO2 flux was positive during night-time and negative during daytime and in phase with convective instability. The CO2 flux relationships with the meteorological parameters such as wind speed, temperature and ...

  19. Dis-aggregation of airborne flux measurements using footprint analysis

    NARCIS (Netherlands)

    Hutjes, R.W.A.; Vellinga, O.S.; Gioli, B.; Miglietta, F.

    2010-01-01

    Aircraft measurements of turbulent fluxes are generally being made with the objective to obtain an estimate of regional exchanges between land surface and atmosphere, to investigate the spatial variability of these fluxes, but also to learn something about the fluxes from some or all of the land

  20. An alternative method for the measurement of neutron flux

    Indian Academy of Sciences (India)

    Abstract. A simple and easy method for measuring the neutron flux is presented. This paper deals with the experimental verification of neutron dose rate–flux relationship for a non-dissipative medium. Though the neutron flux cannot be obtained from the dose rate in a dissipative medium, experimental result shows that for ...

  1. The microscopic investigation of structures of moving flux lines by ...

    Indian Academy of Sciences (India)

    Abstract. We have used a variety of microscopic techniques to reveal the structure and motion of flux line arrangements, when the flux lines in low Tc type II superconductors are caused to move by a transport current. Using small-angle neutron scattering by the flux line lattice (FLL), we are able to demonstrate directly the ...

  2. An alternative method for the measurement of neutron flux

    Indian Academy of Sciences (India)

    A simple and easy method for measuring the neutron flux is presented. This paper deals with the experimental verification of neutron dose rate–flux relationship for a non-dissipative medium. Though the neutron flux cannot be obtained from the dose rate in a dissipative medium, experimental result shows that for ...

  3. Surface renewal method for estimating sensible heat flux | Mengistu ...

    African Journals Online (AJOL)

    For short canopies, latent energy flux may be estimated using a shortened surface energy balance from measurements of sensible and soil heat flux and the net irradiance at the surface. The surface renewal (SR) method for estimating sensible heat, latent energy, and other scalar fluxes has the advantage over other ...

  4. The measurements of thermal neutron flux distribution in a paraffin ...

    Indian Academy of Sciences (India)

    The term `thermal flux' implies a Maxwellian distribution of velocity and energy corresponding to the most probable velocity of 2200 ms-1 at 293.4 K. In order to measure the thermal neutron flux density, the foil activation method was used. Thermal neutron flux determination in paraffin phantom by counting the emitted rays of ...

  5. Properties of Flux Tubes and the Relation with Solar Irradiance ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... At the solar surface the magnetic field is bundled into discrete elements of concentrated flux, often referred to as magnetic flux tubes, which cover only a small fraction of the solar surface. Flux tubes span a whole spectrum of sizes, ranging from sunspots to features well below the best currently obtainable ...

  6. Boosted Fast Flux Loop Alternative Cooling Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Glen R. Longhurst; Donna Post Guillen; James R. Parry; Douglas L. Porter; Bruce W. Wallace

    2007-08-01

    The Gas Test Loop (GTL) Project was instituted to develop the means for conducting fast neutron irradiation tests in a domestic radiation facility. It made use of booster fuel to achieve the high neutron flux, a hafnium thermal neutron absorber to attain the high fast-to-thermal flux ratio, a mixed gas temperature control system for maintaining experiment temperatures, and a compressed gas cooling system to remove heat from the experiment capsules and the hafnium thermal neutron absorber. This GTL system was determined to provide a fast (E > 0.1 MeV) flux greater than 1.0E+15 n/cm2-s with a fast-to-thermal flux ratio in the vicinity of 40. However, the estimated system acquisition cost from earlier studies was deemed to be high. That cost was strongly influenced by the compressed gas cooling system for experiment heat removal. Designers were challenged to find a less expensive way to achieve the required cooling. This report documents the results of the investigation leading to an alternatively cooled configuration, referred to now as the Boosted Fast Flux Loop (BFFL). This configuration relies on a composite material comprised of hafnium aluminide (Al3Hf) in an aluminum matrix to transfer heat from the experiment to pressurized water cooling channels while at the same time providing absorption of thermal neutrons. Investigations into the performance this configuration might achieve showed that it should perform at least as well as its gas-cooled predecessor. Physics calculations indicated that the fast neutron flux averaged over the central 40 cm (16 inches) relative to ATR core mid-plane in irradiation spaces would be about 1.04E+15 n/cm2-s. The fast-to-thermal flux ratio would be in excess of 40. Further, the particular configuration of cooling channels was relatively unimportant compared with the total amount of water in the apparatus in determining performance. Thermal analyses conducted on a candidate configuration showed the design of the water coolant and

  7. NEON's eddy-covariance: interoperable flux data products, software and services for you, now

    Science.gov (United States)

    Metzger, S.; Desai, A. R.; Durden, D.; Hartmann, J.; Li, J.; Luo, H.; Durden, N. P.; Sachs, T.; Serafimovich, A.; Sturtevant, C.; Xu, K.

    2017-12-01

    Networks of eddy-covariance (EC) towers such as AmeriFlux, ICOS and NEON are vital for providing the necessary distributed observations to address interactions at the soil-vegetation-atmosphere interface. NEON, close to full operation with 47 tower sites, will represent the largest single-provider EC network globally. Its standardized observation and data processing suite is designed specifically for inter-site comparability and analysis of feedbacks across multiple spatial and temporal scales. Furthermore, NEON coordinates EC with rich contextual observations such as airborne remote sensing and in-situ sampling bouts. In January 2018 NEON enters its operational phase, and EC data products, software and services become fully available to the science community at large. These resources strive to incorporate lessons-learned through collaborations with AmeriFlux, ICOS, LTER and others, to suggest novel systemic solutions, and to synergize ongoing research efforts across science communities. Here, we present an overview of the ongoing product release, alongside efforts to integrate and collaborate with existing infrastructures, networks and communities. Near-real-time heat, water and carbon cycle observations in "basic" and "expanded", self-describing HDF5 formats become accessible from the NEON Data Portal, including an Application Program Interface. Subsequently, they are ingested into the AmeriFlux processing pipeline, together with inclusion in FLUXNET globally harmonized data releases. Software for reproducible, extensible and portable data analysis and science operations management also becomes available. This includes the eddy4R family of R-packages underlying the data product generation, together with the ability to directly participate in open development via GitHub version control and DockerHub image hosting. In addition, templates for science operations management include a web-based field maintenance application and a graphical user interface to simplify

  8. Promoting the potential of flux-measuring stations in urban parks: An innovative case study in Naples, Italy

    Czech Academy of Sciences Publication Activity Database

    Guidolotti, G.; Calfapietra, Carlo; Pallozzi, E.; De Simoni, G.; Esposito, R.; Mattioni, M.; Nicolini, G.; Matteucci, G.; Brugnoli, E.

    2017-01-01

    Roč. 233, feb (2017), s. 153-162 ISSN 0168-1923 R&D Projects: GA MŠk(CZ) LO1415; GA MŠk(CZ) LD13031 Institutional support: RVO:86652079 Keywords : eddy covariance measurements * net ecosystem exchange * carbon-dioxide fluxes * ozone deposition * air-quality * mediterranean forest * surface fluxes * climate-change * quercus-ilex * water-vapor * Urban forest * Eddy covariance * Greenhouse gases * bvoc * Air pollutants Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 3.887, year: 2016

  9. A novel approach to evaluate soil heat flux calculation: An analytical review of nine methods: Soil Heat Flux Calculation

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhongming [Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman Washington USA; Russell, Eric S. [Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman Washington USA; Missik, Justine E. C. [Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman Washington USA; Huang, Maoyi [Pacific Northwest National Laboratory, Richland Washington USA; Chen, Xingyuan [Pacific Northwest National Laboratory, Richland Washington USA; Strickland, Chris E. [Pacific Northwest National Laboratory, Richland Washington USA; Clayton, Ray [Pacific Northwest National Laboratory, Richland Washington USA; Arntzen, Evan [Pacific Northwest National Laboratory, Richland Washington USA; Ma, Yulong [Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman Washington USA; Liu, Heping [Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman Washington USA

    2017-07-12

    We evaluated nine methods of soil heat flux calculation using field observations. All nine methods underestimated the soil heat flux by at least 19%. This large underestimation is mainly caused by uncertainties in soil thermal properties.

  10. The AmeriFlux data activity and data system: an evolving collection of data management techniques, tools, products and services

    Directory of Open Access Journals (Sweden)

    T. A. Boden

    2013-06-01

    Full Text Available The Carbon Dioxide Information Analysis Center (CDIAC at Oak Ridge National Laboratory (ORNL, USA has provided scientific data management support for the US Department of Energy and international climate change science since 1982. Among the many data archived and available from CDIAC are collections from long-term measurement projects. One current example is the AmeriFlux measurement network. AmeriFlux provides continuous measurements from forests, grasslands, wetlands, and croplands in North, Central, and South America and offers important insight about carbon cycling in terrestrial ecosystems. To successfully manage AmeriFlux data and support climate change research, CDIAC has designed flexible data systems using proven technologies and standards blended with new, evolving technologies and standards. The AmeriFlux data system, comprised primarily of a relational database, a PHP-based data interface and a FTP server, offers a broad suite of AmeriFlux data. The data interface allows users to query the AmeriFlux collection in a variety of ways and then subset, visualize and download the data. From the perspective of data stewardship, on the other hand, this system is designed for CDIAC to easily control database content, automate data movement, track data provenance, manage metadata content, and handle frequent additions and corrections. CDIAC and researchers in the flux community developed data submission guidelines to enhance the AmeriFlux data collection, enable automated data processing, and promote standardization across regional networks. Both continuous flux and meteorological data and irregular biological data collected at AmeriFlux sites are carefully scrutinized by CDIAC using established quality-control algorithms before the data are ingested into the AmeriFlux data system. Other tasks at CDIAC include reformatting and standardizing the diverse and heterogeneous datasets received from individual sites into a uniform and consistent

  11. The AmeriFlux data activity and data system: an evolving collection of data management techniques, tools, products and services

    Science.gov (United States)

    Boden, T. A.; Krassovski, M.; Yang, B.

    2013-06-01

    The Carbon Dioxide Information Analysis Center (CDIAC) at Oak Ridge National Laboratory (ORNL), USA has provided scientific data management support for the US Department of Energy and international climate change science since 1982. Among the many data archived and available from CDIAC are collections from long-term measurement projects. One current example is the AmeriFlux measurement network. AmeriFlux provides continuous measurements from forests, grasslands, wetlands, and croplands in North, Central, and South America and offers important insight about carbon cycling in terrestrial ecosystems. To successfully manage AmeriFlux data and support climate change research, CDIAC has designed flexible data systems using proven technologies and standards blended with new, evolving technologies and standards. The AmeriFlux data system, comprised primarily of a relational database, a PHP-based data interface and a FTP server, offers a broad suite of AmeriFlux data. The data interface allows users to query the AmeriFlux collection in a variety of ways and then subset, visualize and download the data. From the perspective of data stewardship, on the other hand, this system is designed for CDIAC to easily control database content, automate data movement, track data provenance, manage metadata content, and handle frequent additions and corrections. CDIAC and researchers in the flux community developed data submission guidelines to enhance the AmeriFlux data collection, enable automated data processing, and promote standardization across regional networks. Both continuous flux and meteorological data and irregular biological data collected at AmeriFlux sites are carefully scrutinized by CDIAC using established quality-control algorithms before the data are ingested into the AmeriFlux data system. Other tasks at CDIAC include reformatting and standardizing the diverse and heterogeneous datasets received from individual sites into a uniform and consistent network database

  12. Revolutionary Science

    Directory of Open Access Journals (Sweden)

    Arturo Casadevall

    2016-05-01

    Full Text Available On rare occasions in the history of science, remarkable discoveries transform human society and forever alter mankind’s view of the world. Examples of such discoveries include the heliocentric theory, Newtonian physics, the germ theory of disease, quantum theory, plate tectonics and the discovery that DNA carries genetic information. The science philosopher Thomas Kuhn famously described science as long periods of normality punctuated by times of crisis, when anomalous observations culminate in revolutionary changes that replace one paradigm with another. This essay examines several transformative discoveries in the light of Kuhn’s formulation. We find that each scientific revolution is unique, with disparate origins that may include puzzle solving, serendipity, inspiration, or a convergence of disparate observations. The causes of revolutionary science are varied and lack an obvious common structure. Moreover, it can be difficult to draw a clear distinction between so-called normal and revolutionary science. Revolutionary discoveries often emerge from basic science and are critically dependent on nonrevolutionary research. Revolutionary discoveries may be conceptual or technological in nature, lead to the creation of new fields, and have a lasting impact on many fields in addition to the field from which they emerge. In contrast to political revolutions, scientific revolutions do not necessarily require the destruction of the previous order. For humanity to continue to benefit from revolutionary discoveries, a broad palette of scientific inquiry with a particular emphasis on basic science should be supported.

  13. Revolutionary Science.

    Science.gov (United States)

    Casadevall, Arturo; Fang, Ferric C

    2016-03-01

    On rare occasions in the history of science, remarkable discoveries transform human society and forever alter mankind's view of the world. Examples of such discoveries include the heliocentric theory, Newtonian physics, the germ theory of disease, quantum theory, plate tectonics and the discovery that DNA carries genetic information. The science philosopher Thomas Kuhn famously described science as long periods of normality punctuated by times of crisis, when anomalous observations culminate in revolutionary changes that replace one paradigm with another. This essay examines several transformative discoveries in the light of Kuhn's formulation. We find that each scientific revolution is unique, with disparate origins that may include puzzle solving, serendipity, inspiration, or a convergence of disparate observations. The causes of revolutionary science are varied and lack an obvious common structure. Moreover, it can be difficult to draw a clear distinction between so-called normal and revolutionary science. Revolutionary discoveries often emerge from basic science and are critically dependent on nonrevolutionary research. Revolutionary discoveries may be conceptual or technological in nature, lead to the creation of new fields, and have a lasting impact on many fields in addition to the field from which they emerge. In contrast to political revolutions, scientific revolutions do not necessarily require the destruction of the previous order. For humanity to continue to benefit from revolutionary discoveries, a broad palette of scientific inquiry with a particular emphasis on basic science should be supported. Copyright © 2016 Casadevall and Fang.

  14. Science Instructors' Views of Science and Nature of Science

    Science.gov (United States)

    Karakas, Mehmet

    2011-01-01

    This qualitative study examined how college science faculty who teach introductory level undergraduate science courses including the fields of chemistry, biology, physics, and earth science, understand and define science and nature of science (NOS). Participants were seventeen science instructors from five different institutions in the…

  15. Design of a Modular E-Core Flux Concentrating Axial Flux Machine: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Husain, Tausif; Sozer, Yilmaz; Husain, Iqbal; Muljadi, Eduard

    2015-08-24

    In this paper a novel E-Core axial flux machine is proposed. The machine has a double-stator, single-rotor configuration with flux-concentrating ferrite magnets and pole windings across each leg of an E-Core stator. E-Core stators with the proposed flux-concentrating rotor arrangement result in better magnet utilization and higher torque density. The machine also has a modular structure facilitating simpler construction. This paper presents a single-phase and a three-phase version of the E-Core machine. Case studies for a 1.1-kW, 400-rpm machine for both the single-phase and three-phase axial flux machines are presented. The results are verified through 3D finite element analysis. facilitating simpler construction. This paper presents a single-phase and a three-phase version of the E-Core machine. Case studies for a 1.1-kW, 400-rpm machine for both the single-phase and three-phase axial flux machines are presented. The results are verified through 3D finite element analysis.

  16. Flux pinning and flux flow studies in superconductors using flux flow noise techniques. Progress report, April 1, 1976--December 17, 1976

    International Nuclear Information System (INIS)

    Joiner, W.C.H.

    1976-12-01

    Measurements of flux flow noise power spectra have been combined with critical current measurements and measurements of current-voltage characteristics to study flux flow and local pinning interactions effective during flux flow. A model of flux flow noise generation in the presence of local pinning interactions is developed and applied to situations where pinning is dominated by: (1) grain boundaries, (2) normal metal precipitates in a superconducting matrix, (3) gross deformation producing a critical current peak effect, and (4) surface grooves imposed on a sample surface. In the case of pinning caused by normal metal precipitates in a superconducting matrix, unusual training and hysterisis effects are observed in the flux flow characteristics. The greater sensitivity of noise spectra, as compared with bulk critical current measurements, in obtaining a detailed picture of flux flow is emphasized

  17. Effect of skim milk treated with high hydrostatic pressure on permeate flux and fouling during ultrafiltration.

    Science.gov (United States)

    Leu, Mathilde; Marciniak, Alice; Chamberland, Julien; Pouliot, Yves; Bazinet, Laurent; Doyen, Alain

    2017-09-01

    Ultrafiltration (UF) is largely used in the dairy industry to generate milk and whey protein concentrate for standardization of milk or production of dairy ingredients. Recently, it was demonstrated that high hydrostatic pressure (HHP) extended the shelf life of milk and improved rennet coagulation and cheese yield. Pressurization also modified casein micelle size distribution and promoted aggregation of whey proteins. These changes are likely to affect UF performance. Consequently, this study determined the effect of skim milk pressurization (300 and 600 MPa, 5 min) on UF performance in terms of permeate flux decline and fouling. The effect of HHP on milk proteins was first studied and UF was performed in total recycle mode at different transmembrane pressures to determine optimal UF operational parameters and to evaluate the effect of pressurization on critical and limiting fluxes. Ultrafiltration was also performed in concentration mode at a transmembrane pressure of 345 kPa for 130 or 140 min to evaluate the decline of permeate flux and to determine fouling resistances. It was observed that average casein micelle size decreased by 32 and 38%, whereas β-lactoglobulin denaturation reached 30 and 70% at 300 and 600 MPa, respectively. These results were directly related to UF performance because initial permeate fluxes in total recycle mode decreased by 25% at 300 and 600 MPa compared with nonpressurized milk, critical flux, and limiting flux, which were lower during UF of milk treated with HHP. During UF in concentration mode, initial permeate fluxes were 30% lower at 300 and 600 MPa compared with the control, but the total flux decline was higher for nonpressurized milk (62%) compared with pressure-treated milk (30%). Fouling resistances were similar, whatever the treatment, except at 600 MPa where irreversible fouling was higher. Characterization of the fouling layer showed that caseins and β-lactoglobulin were mainly involved in membrane fouling after UF of

  18. The development, evaluation, and application of O3 flux and flux-response models for additional agricultural crops

    Science.gov (United States)

    L. D. Emberson; W. J. Massman; P. Buker; G. Soja; I. Van De Sand; G. Mills; C. Jacobs

    2006-01-01

    Currently, stomatal O3 flux and flux-response models only exist for wheat and potato (LRTAP Convention, 2004), as such there is a need to extend these models to include additional crop types. The possibility of establishing robust stomatal flux models for five agricultural crops (tomato, grapevine, sugar beet, maize and sunflower) was investigated. These crops were...

  19. The influence of humidity fluxes on offshore wind speed profiles

    DEFF Research Database (Denmark)

    Barthelmie, Rebecca Jane; Sempreviva, Anna Maria; Pryor, Sara

    2010-01-01

    extrapolation from lower measurements. With humid conditions and low mechanical turbulence offshore, deviations from the traditional logarithmic wind speed profile become significant and stability corrections are required. This research focuses on quantifying the effect of humidity fluxes on stability corrected...... wind speed profiles. The effect on wind speed profiles is found to be important in stable conditions where including humidity fluxes forces conditions towards neutral. Our results show that excluding humidity fluxes leads to average predicted wind speeds at 150 m from 10 m which are up to 4% higher...... than if humidity fluxes are included, and the results are not very sensitive to the method selected to estimate humidity fluxes....

  20. Asymmetric flux generation and its relaxation in reversed field pinch

    International Nuclear Information System (INIS)

    Arimoto, H.; Masamune, S.; Nagata, A.

    1985-02-01

    The toroidally asymmetric flux enhancement [''dynamo effect''] and the axisymmetrization of the enhanced fluxes that follows in the setting up phase of Reversed Field Pinch are investigated on the STP-3[M] device. A rapid increase in the toroidal flux generated by the dynamo effect is first observed near the poloidal and toroidal current feeders. Then, this inhomogeneity of the flux propagates toroidally towards the plasma current. The axisymmetrization of the flux is attained just after the maximum of plasma current. The MHD activities decrease significantly after this axisymmetrization and the quiescent period is obtained. (author)

  1. An Algorithm for Induction Motor Stator Flux Estimation

    Directory of Open Access Journals (Sweden)

    STOJIC, D. M.

    2012-08-01

    Full Text Available A new method for the induction motor stator flux estimation used in the sensorless IM drive applications is presented in this paper. Proposed algorithm advantageously solves problems associated with the pure integration, commonly used for the stator flux estimation. An observer-based structure is proposed based on the stator flux vector stationary state, in order to eliminate the undesired DC offset component present in the integrator based stator flux estimates. By using a set of simulation runs it is shown that the proposed algorithm enables the DC-offset free stator flux estimated for both low and high stator frequency induction motor operation.

  2. Spectroscopy and coherent manipulation of single and coupled flux qubits

    International Nuclear Information System (INIS)

    Wu Yu-Lin; Deng Hui; Huang Ke-Qiang; Tian Ye; Yu Hai-Feng; Xue Guang-Ming; Jin Yi-Rong; Li Jie; Zhao Shi-Ping; Zheng Dong-Ning

    2013-01-01

    Measurements of three-junction flux qubits, both single flux qubits and coupled flux qubits, using a coupled direct current superconducting quantum interference device (dc-SQUID) for readout are reported. The measurement procedure is described in detail. We performed spectroscopy measurements and coherent manipulations of the qubit states on a single flux qubit, demonstrating quantum energy levels and Rabi oscillations, with Rabi oscillation decay time T Rabi = 78 ns and energy relaxation time T 1 = 315 ns. We found that the value of T Rabi depends strongly on the mutual inductance between the qubit and the magnetic coil. We also performed spectroscopy measurements on inductively coupled flux qubits. (general)

  3. Interplanetary dust fluxes, solar and galactic cosmic rays

    International Nuclear Information System (INIS)

    Bel'skij, S.A.

    1978-01-01

    The role of dust fluxes in cosmic ray (CR) propagation in the interplanetary space is investigated. Global effects arising in the interaction of CR with magnetic and electric fields of a sporadic meteor cloud or of all meteor fluxes as a whole are discussed. The local effects arising in the interaction of CR with magnetic and electric fields of separate meteor fluxes are also considered. It is shown that an increase in the CR intensity during the maximum activity of meteor fluxes confirms the supposition on the CR acceleration in electric fields of meteor fluxes

  4. Static flux bias of a flux qubit using persistent current trapping

    International Nuclear Information System (INIS)

    Castellano, Maria Gabriella; Chiarello, Fabio; Torrioli, Guido; Carelli, Pasquale

    2006-01-01

    Qubits based on the magnetic flux degree of freedom require a flux bias, the stability and precision of which strongly affect the qubit performance, up to a point of forbidding the qubit operation. Moreover, in multiqubit systems it must be possible to flux bias each qubit independently, hence avoiding the traditional use of externally generated magnetic fields in favour of on-chip techniques that minimize cross-couplings. The solution discussed in this paper exploits a persistent current trapped in a superconducting circuit integrated on chip that can be inductively coupled with an individual qubit. The circuit does not make use of resistive elements which can be detrimental for qubit coherence. The trapping procedure allows us to control and change stepwise the amount of stored current; after that the circuit can be completely disconnected from the external sources. We show in a practical case how this works and how to drive the bias circuit at the required value

  5. Environmental sciences

    NARCIS (Netherlands)

    Kwa, C.; Wright, J.D.

    2015-01-01

    The environmental sciences are engaged in a remarkable effort of interdisciplinary cooperation and integration. Some long-running international scientific programs, notably the World Climate Research Programme and the International Geosphere-Biosphere Programme, play an important role therein. The

  6. Big science

    CERN Multimedia

    Nadis, S

    2003-01-01

    " "Big science" is moving into astronomy, bringing large experimental teams, multi-year research projects, and big budgets. If this is the wave of the future, why are some astronomers bucking the trend?" (2 pages).

  7. Forensic Science.

    Science.gov (United States)

    Brettell, T. A.; Saferstein, R.

    1989-01-01

    Presents a review of articles appealing to forensic practitioners. Topics include: drugs and poisons, forensic biochemistry, and trace evidence. Lists noteworthy books published on forensic science topics since 1986. (MVL)

  8. Science Smiles

    Indian Academy of Sciences (India)

    IAS Admin

    Page 1. 582. RESONANCE | July 2016. Science Smiles. Ayan Guha. “Ribbed breathing flesh, thrice often crucified,. Veined vase of life, the wheeling universe.” – Sir Charles Sherrington. Email for Correspondence: ionguha@gmail.com.

  9. Science Smiles

    Indian Academy of Sciences (India)

    Page 1. 408. RESONANCE │ May 2011. GENERAL │ ARTICLE. Email for Correspondence: ionguha@gmail.com. Science Smiles. Ayan Guha. It feels like I am posing with the Bourbaki group, where every member is a Zeldovich.

  10. Science Smiles

    Indian Academy of Sciences (India)

    IAS Admin

    Page 1. 1084. RESONANCE | December 2015. Science Smiles. Ayan Guha. Charles H Townes, James P Gordon and H J. Zeiger had the first Maser working about three months later.. Email for Correspondence: ionguha@gmail.com.

  11. Citizen Science

    Science.gov (United States)

    Citizen Science is a fast-growing field in which scientific investigations are conducted by volunteers, which have been successful in expanding scientific knowledge, raising environmental awareness, and leveraging change.

  12. Dismal science.

    Science.gov (United States)

    Evans, Robert G

    2009-05-01

    "No prediction, no science." By this standard, the past year has not been kind to the pretensions of "economic science," Nobel prizes notwithstanding. The issue is more than semantic. As Neil Postman (1992) pointed out, sciences study natural processes that repeat themselves under constant conditions. The social disciplines study practices of human communities that are embedded in history. There are no constant conditions; it is impossible to step into the same river twice (Heraclitus). "Physics envy" has led mainstream economic theorists to attempt to understand their discipline through methods and models borrowed from the natural sciences. (By unfortunate coincidence, these have reinforced a certain class of ideological preconceptions and associated economic interests.) Today the results of this methodological mismatch speak for themselves.

  13. Science Bubbles

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Pedersen, David Budtz

    2013-01-01

    Much like the trade and trait sof bubbles in financial markets,similar bubbles appear on the science market. When economic bubbles burst, the drop in prices causes the crash of unsustainable investments leading to an investor confidence crisis possibly followed by a financial panic. But when bubb...... bubbles appear in science, truth and reliability are the first victims. This paper explores how fashions in research funding and research management may turn science into something like a bubble economy.......Much like the trade and trait sof bubbles in financial markets,similar bubbles appear on the science market. When economic bubbles burst, the drop in prices causes the crash of unsustainable investments leading to an investor confidence crisis possibly followed by a financial panic. But when...

  14. Science Topics

    Science.gov (United States)

    EPA is one of the world’s leading environmental and human health research organizations. Science provides the foundation for Agency policies, actions, and decisions made on behalf of the American people.

  15. Molecular sciences

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    The research in molecular sciences summarized includes photochemistry, radiation chemistry, geophysics, electromechanics, heavy-element oxidizers , heavy element chemistry collisions, atoms, organic solids. A list of publications is included

  16. Earth Sciences

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    The following papers were presented at the earth science session: earth science developments in support of water isolation; development of models and parameters for ground-water flow in fractured rock masses; isotope geochemistry as a tool for determining regional ground-water flow; natural analogs of radionuclide migration; nuclide retardation data: its use in the NWTS program; and ground-water geochemistry and interaction with basalt at Hanford

  17. World science

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    The aim of the Third World Network of Scientific Organizations (TWNSO), established last year with its headquarters in Trieste, Italy, is to promote the role of science and technology in developing countries. TWNSO, under the presidency of Abdus Salam, is an offshoot of the Third World Academy of Sciences, which has pushed the cause of international scientific collaboration since its establishment in 1983. (orig./HSI).

  18. WATER RESOURCES. Hydrologic connectivity constrains partitioning of global terrestrial water fluxes.

    Science.gov (United States)

    Good, Stephen P; Noone, David; Bowen, Gabriel

    2015-07-10

    Continental precipitation not routed to the oceans as runoff returns to the atmosphere as evapotranspiration. Partitioning this evapotranspiration flux into interception, transpiration, soil evaporation, and surface water evaporation is difficult using traditional hydrological methods, yet critical for understanding the water cycle and linked ecological processes. We combined two large-scale flux-partitioning approaches to quantify evapotranspiration subcomponents and the hydrologic connectivity of bound, plant-available soil waters with more mobile surface waters. Globally, transpiration is 64 ± 13% (mean ± 1 standard deviation) of evapotranspiration, and 65 ± 26% of evaporation originates from soils and not surface waters. We estimate that 38 ± 28% of surface water is derived from the plant-accessed soil water pool. This limited connectivity between soil and surface waters fundamentally structures the physical and biogeochemical interactions of water transiting through catchments. Copyright © 2015, American Association for the Advancement of Science.

  19. External trabeculectomy with T-Flux implant.

    LENUS (Irish Health Repository)

    Jungkim, S

    2012-02-03

    PURPOSE: To evaluate the efficacy and safety of T-Flux implant in nonpenetrating glaucoma surgery. METHODS: This clinical interventional case series study included 35 eyes of 35 patients with medically uncontrolled primary open angle glaucoma. External trabeculectomy with T-Flux (ETTF) is a technique of nonpenetrating glaucoma surgery, in which after removing deep scleral tissue and un-roofing the canal of Schlemn (CS) the external trabecular tissue is peeled off to enhance the aqueous drainage without opening the anterior chamber. A non-absorbable T-Flux implant (IOL TECH Laboratories, France) was sutured in deep intrascleral space to keep it patent. Snellen\\'s best-corrected visual acuity, slit lamp biomicroscopy, intraocular pressure (IOP), gonioscopy, funduscopy, and optic disc assessment were performed preoperatively and postoperatively at 1 day, 1 week, and 1, 3 , 6, and 12 months. Visual field testing was performed preoperatively and at 6 and 12 months postoperatively. RESULTS: For three eyes, surgery was converted to standard trabeculectomy owing to the perforation of trabeculo-Descemet\\'s membrane and iris prolapse and excluded from the study. The results of the remaining 32 eyes were included in the study. Preoperative IOP (mean +\\/- SD) of 32.88 +\\/- 5.7 mmHg decreased to 15.44 +\\/- 1.6 mmHg after 12 months. Ten eyes (28.6%) had microhyphema that resolved spontaneously; 3 eyes (8.6%) had microperforation without iris prolapse so ETTF was proceeded routinely. The preoperative number of antiglaucoma medications per patient reduced from (mean +\\/- SD) 2.74 +\\/- 0.61 to 0.11 +\\/- 0.32 postoperatively at 12 months. Visual acuity and visual fields remained stable. CONCLUSIONS: ETTF appears to provide significant control of IOP and have low incidence of complications.

  20. Metabolic fuels: regulating fluxes to select mix.

    Science.gov (United States)

    Weber, Jean-Michel

    2011-01-15

    Animals must regulate the fluxes of multiple fuels to support changing metabolic rates that result from variation in physiological circumstances. The aim of fuel selection strategies is to exploit the advantages of individual substrates while minimizing the impact of disadvantages. All exercising mammals share a general pattern of fuel selection: at the same %V(O(2,max)) they oxidize the same ratio of lipids to carbohydrates. However, highly aerobic species rely more on intramuscular fuels because energy supply from the circulation is constrained by trans-sarcolemmal transfer. Fuel selection is performed by recruiting different muscles, different fibers within the same muscles or different pathways within the same fibers. Electromyographic analyses show that shivering humans can modulate carbohydrate oxidation either through the selective recruitment of type II fibers within the same muscles or by regulating pathway recruitment within type I fibers. The selection patterns of shivering and exercise are different: at the same %V(O(2,max)), a muscle producing only heat (shivering) or significant movement (exercise) strikes a different balance between lipid and carbohydrate oxidation. Long-distance migrants provide an excellent model to characterize how to increase maximal substrate fluxes. High lipid fluxes are achieved through the coordinated upregulation of mobilization, transport and oxidation by activating enzymes, lipid-solubilizing proteins and membrane transporters. These endurance athletes support record lipolytic rates in adipocytes, use lipoprotein shuttles to accelerate transport and show increased capacity for lipid oxidation in muscle mitochondria. Some migrant birds use dietary omega-3 fatty acids as performance-enhancing agents to boost their ability to process lipids. These dietary fatty acids become incorporated in membrane phospholipids and bind to peroxisome proliferator-activated receptors to activate membrane proteins and modify gene expression.

  1. Probabilistic Forecasting of the Wave Energy Flux

    DEFF Research Database (Denmark)

    Pinson, Pierre; Reikard, G.; Bidlot, J.-R.

    2012-01-01

    Wave energy will certainly have a significant role to play in the deployment of renewable energy generation capacities. As with wind and solar, probabilistic forecasts of wave power over horizons of a few hours to a few days are required for power system operation as well as trading in electricity...... markets. A methodology for the probabilistic forecasting of the wave energy flux is introduced, based on a log-Normal assumption for the shape of predictive densities. It uses meteorological forecasts (from the European Centre for Medium-range Weather Forecasts – ECMWF) and local wave measurements...

  2. Contactless heat flux control with photonic devices

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Abdallah, Philippe, E-mail: pba@institutoptique.fr [Laboratoire Charles Fabry, UMR 8501, Institut d’Optique, CNRS, Université Paris-Sud 11, 2, Avenue Augustin Fresnel, 91127 Palaiseau Cedex (France); Biehs, Svend-Age, E-mail: s.age.biehs@uni-oldenburg.de [Institut für Physik, Carl von Ossietzky Universität, D-26111 Oldenburg (Germany)

    2015-05-15

    The ability to control electric currents in solids using diodes and transistors is undoubtedly at the origin of the main developments in modern electronics which have revolutionized the daily life in the second half of 20th century. Surprisingly, until the year 2000 no thermal counterpart for such a control had been proposed. Since then, based on pioneering works on the control of phononic heat currents new devices were proposed which allow for the control of heat fluxes carried by photons rather than phonons or electrons. The goal of the present paper is to summarize the main advances achieved recently in the field of thermal energy control with photons.

  3. Geometric Algebra Techniques in Flux Compactifications

    International Nuclear Information System (INIS)

    Coman, Ioana Alexandra; Lazaroiu, Calin Iuliu; Babalic, Elena Mirela

    2016-01-01

    We study “constrained generalized Killing (s)pinors,” which characterize supersymmetric flux compactifications of supergravity theories. Using geometric algebra techniques, we give conceptually clear and computationally effective methods for translating supersymmetry conditions into differential and algebraic constraints on collections of differential forms. In particular, we give a synthetic description of Fierz identities, which are an important ingredient of such problems. As an application, we show how our approach can be used to efficiently treat N=1 compactification of M-theory on eight manifolds and prove that we recover results previously obtained in the literature.

  4. Fast flux test facility noise data management

    International Nuclear Information System (INIS)

    Thie, J.A.

    1988-01-01

    An extensive collection of spectra from an automated data collection system at the Fast Flux Facility has features from neutron data extracted and managed by database software. Inquiry techniques, including screening, applied to database results show the influences of control rods on wideband noise and, more generally, abilities to detect diverse types of off-normal noise. Uncovering a temporary 0.1-Hz resonance shift gave additional diagnostic information on a 13-Hz mechanical motion characterized by the interference of two resonances. The latter phenomenon is discussed generically for possible application to other reactor types. (author)

  5. Radiation linewidth of flux-flow oscillators

    DEFF Research Database (Denmark)

    Koshelets, V.P.; Dmitriev, P.N.; Ermakov, A.B.

    2001-01-01

    The results of linewidth measurements on flux-flow oscillators (FFOs) of a new design with improved parameters are presented. Extensive measurements of the dependence of the free-running FFO linewidth on the differential resistances associated both with the bias current and the control-line current....... A phenomenological model of the FFO linewidth taking into account all known noise sources (both internal and external) is used to explain the FFO linewidth dependence on the experimental parameters. Finally, we discuss the feasibility of using an electronic phase-locking loop (PLL) over the entire FFO operational...

  6. Coherence properties in superconducting flux qubits

    Energy Technology Data Exchange (ETDEWEB)

    Spilla, Samuele

    2015-02-16

    The research work discussed in this thesis deals with the study of superconducting Josephson qubits. Superconducting qubits are solid-state artificial atoms which are based on lithographically defined Josephson tunnel junctions properties. When sufficiently cooled, these superconducting devices exhibit quantized states of charge, flux or junction phase depending on their design parameters. This allows to observe coherent evolutions of their states. The results presented can be divided into two parts. In a first part we investigate operations of superconducting qubits based on the quantum coherence in superconducting quantum interference devices (SQUID). We explain experimental data which has been observed in a SQUID subjected to fast, large-amplitude modifications of its effective potential shape. The motivations for this work come from the fact that in the past few years there have been attempts to interpret the supposed quantum behavior of physical systems, such as Josephson devices, within a classical framework. Moreover, we analyze the possibility of generating GHZ states, namely maximally entangled states, in a quantum system made out of three Josephson qubits. In particular, we investigate the possible limitations of the GHZ state generation due to coupling to bosonic baths. In the second part of the thesis we address a particular cause of decoherence of flux qubits which has been disregarded until now: thermal gradients, which can arise due to accidental non equilibrium quasiparticle distributions. The reason for these detrimental effects is that heat currents flowing through Josephson tunnel junctions in response to a temperature gradient are periodic functions of the phase difference between the electrodes. The phase dependence of the heat current comes from Andreev reflection, namely an interplay between the quasiparticles which carry heat and the superconducting condensate which is sensitive to the superconducting phase difference. Generally speaking

  7. Heterotic Hyper-Kähler flux backgrounds

    Science.gov (United States)

    Halmagyi, Nick; Israël, Dan; Sarkis, Matthieu; Svanes, Eirik Eik

    2017-08-01

    We study Heterotic supergravity on Hyper-Kähler manifolds in the presence of non-trivial warping and three form flux with Abelian bundles in the large charge limit. We find exact, regular solutions for multi-centered Gibbons-Hawking spaces and Atiyah-Hitchin manifolds. In the case of Atiyah-Hitchin, regularity requires that the circle at infinity is of the same order as the instanton number, which is taken to be large. Alternatively there may be a non-trivial density of smeared five branes at the bolt.

  8. Experimental study of the atmospheric neutrino flux

    International Nuclear Information System (INIS)

    Hirata, K.S.; Kajita, T.; Koshiba, M.

    1988-01-01

    We have observed 277 fully contained events in the KAMIOKANDE detector. The number of electron-like single prong events is in good agreement with the predictions of a Monte Carlo calculation based on atmospheric neutrino interactions in the detector. On the other hand, the number of muon-like single prong events is 59 ± 7 %(statistical error) of the predicted number of the Monte Carlo calculation. We are unable to explain the data as the result of systematic detector effects or uncertainties in the atmospheric neutrino fluxes. (author)

  9. Ultraviolet Flux Variation of Epsilon Aurigae

    Directory of Open Access Journals (Sweden)

    Young Woon Kang

    1990-06-01

    Full Text Available The eighteen ultraviolet light curves of Epsilon Aurigae have been plotted using the integrated fluxes reduced from the 233 IUE low dispersion spectra taken between 1978 and 1986. The times of contacts and depth of eclipse have been determined from the light curves at the wavelength from 2550 Å to 3050 Å. The UV light curves show two brightenings during the totality, the downward slope of the variation from the second to the third contacts, and asymmetry of the eclipse light curve. The two selected spectra note that the energy density distribution is not changed between the totality of the eclipse and out-of-eclipse.

  10. Effect of Flux Adjustments on Temperature Variability in Climate Models

    International Nuclear Information System (INIS)

    Duffy, P.; Bell, J.; Covey, C.; Sloan, L.

    1999-01-01

    It has been suggested that ''flux adjustments'' in climate models suppress simulated temperature variability. If true, this might invalidate the conclusion that at least some of observed temperature increases since 1860 are anthropogenic, since this conclusion is based in part on estimates of natural temperature variability derived from flux-adjusted models. We assess variability of surface air temperatures in 17 simulations of internal temperature variability submitted to the Coupled Model Intercomparison Project. By comparing variability in flux-adjusted vs. non-flux adjusted simulations, we find no evidence that flux adjustments suppress temperature variability in climate models; other, largely unknown, factors are much more important in determining simulated temperature variability. Therefore the conclusion that at least some of observed temperature increases are anthropogenic cannot be questioned on the grounds that it is based in part on results of flux-adjusted models. Also, reducing or eliminating flux adjustments would probably do little to improve simulations of temperature variability

  11. JPRS Report Science & Technology USSR: Life Sciences

    National Research Council Canada - National Science Library

    1988-01-01

    ...: Life sciences, aerospace medicine, agriculture science, biochemistry, biophysics, genetics, immunology, industrial medicine, laser bioeffects, medicine, molecular biology, nonionizing radiation...

  12. Neutron scattering at the high-flux isotope reactor

    International Nuclear Information System (INIS)

    Cable, J.W. Chakoumakos, B.C.; Dai, P.

    1995-01-01

    The title facilities offer the brightest source of neutrons in the national user program. Neutron scattering experiments probe the structure and dynamics of materials in unique and complementary ways as compared to x-ray scattering methods and provide fundamental data on materials of interest to solid state physicists, chemists, biologists, polymer scientists, colloid scientists, mineralogists, and metallurgists. Instrumentation at the High- Flux Isotope Reactor includes triple-axis spectrometers for inelastic scattering experiments, a single-crystal four diffractometer for crystal structural studies, a high-resolution powder diffractometer for nuclear and magnetic structure studies, a wide-angle diffractometer for dynamic powder studies and measurements of diffuse scattering in crystals, a small-angle neutron scattering (SANS) instrument used primarily to study structure-function relationships in polymers and biological macromolecules, a neutron reflectometer for studies of surface and thin-film structures, and residual stress instrumentation for determining macro- and micro-stresses in structural metals and ceramics. Research highlights of these areas will illustrate the current state of neutron science to study the physical properties of materials

  13. Colour in flux: describing and printing colour in art

    Science.gov (United States)

    Parraman, Carinna

    2008-01-01

    This presentation will describe artists, practitioners and scientists, who were interested in developing a deeper psychological, emotional and practical understanding of the human visual system who were working with wavelength, paint and other materials. From a selection of prints at The Prints and Drawings Department at Tate London, the presentation will refer to artists who were motivated by issues relating to how colour pigment was mixed and printed, to interrogate and explain colour perception and colour science, and in art, how artists have used colour to challenge the viewer and how a viewer might describe their experience of colour. The title Colour in Flux refers, not only to the perceptual effect of the juxtaposition of one colour pigment with another, but also to the changes and challenges for the print industry. In the light of screenprinted examples from the 60s and 70s, the presentation will discuss 21 st century ideas on colour and how these notions have informed the Centre for Fine Print Research's (CFPR) practical research in colour printing. The latter part of this presentation will discuss the implications for the need to change methods in mixing inks that moves away from existing colour spaces, from non intuitive colour mixing to bespoke ink sets, colour mixing approaches and colour mixing methods that are not reliant on RGB or CMYK.

  14. Carbonyl Sulfide for Tracing Carbon Fluxes Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J. Elliott [Univ. of California, Merced, CA (United States); Berry, Joseph A. [Carnegie Inst. of Science, Stanford, CA (United States); Billesbach, Dave [Univ. of Nebraska, Lincoln, NE (United States); Torn, Margaret S [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zahniser, Mark [Aerodyne Research, Inc., Billerica, MA (United States); Seibt, Ulrike [Univ. of California, Los Angeles, CA (United States); Maseyk, Kadmiel [Pierre and Marie Curie Univ., Paris (France)

    2016-04-01

    The April-June 2012 campaign was located at the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Southern Great Plains (SGP) site Central Facility and had three purposes. One goal was to demonstrate the ability of current instrumentation to correctly measure fluxes of atmospheric carbonyl sulfide (COS). The approach has been describe previously as a critical approach to advancing carbon cycle science1,2, but requires further investigation at the canopy scale to resolve ecosystem processes. Previous canopy-scale efforts were limited to data rates of 1Hz. While 1 Hz measurements may work in a few ecosystems, it is widely accepted that data rates of 10 to 20 Hz are needed to fully capture the exchange of traces gases between the atmosphere and vegetative canopy. A second goal of this campaign was to determine if canopy observations could provide information to help interpret the seasonal double peak in airborne observations at SGP of CO2 and COS mixing ratios. A third goal was to detect potential sources and sinks of COS that must be resolved before using COS as a tracer of gross primary productivity (GPP).

  15. Partitioning of water flux in a Sierra Nevada ponderosa pine plantation

    Science.gov (United States)

    Kurpius, M.R.; Panek, J.A.; Nikolov, N.T.; McKay, M.; Goldstein, Allen H.

    2003-01-01

    The weather patterns of the west side of the Sierra Nevada Mountains (cold, wet winters and hot, dry summers) strongly influence how water is partitioned between transpiration and evaporation and result in a specific strategy of water use by ponderosa pine trees (Pinus ponderosa) in this region. To investigate how year-round water fluxes were partitioned in a young ponderosa pine ecosystem in the Sierra Nevada Mountains, water fluxes were continually measured from June 2000 to May 2001 using a combination of sap flow and eddy covariance techniques (above- and below-canopy). Water fluxes were modeled at our study site using a biophysical model, FORFLUX. During summer and fall water fluxes were equally partitioned between transpiration and soil evaporation while transpiration dominated the water fluxes in winter and spring. The trees had high rates of canopy conductance and transpiration in the early morning and mid-late afternoon and a mid-day depression during the dry season. We used a diurnal centroid analysis to show that the timing of high canopy conductance and transpiration relative to high vapor pressure deficit (D) shifted with soil moisture: during periods of low soil moisture canopy conductance and transpiration peaked early in the day when D was low. Conversely, during periods of high soil moisture canopy conductance and transpiration peaked at the same time or later in the day than D. Our observations suggest a general strategy by the pine trees in which they maximize stomatal conductance, and therefore carbon fixation, throughout the day on warm sunny days with high soil moisture (i.e. warm periods in winter and late spring) and maximize stomatal conductance and carbon fixation in the morning through the dry periods. FORFLUX model estimates of evaporation and transpiration were close to measured/calculated values during the dry period, including the drought, but underestimated transpiration and overestimated evaporation during the wet period. ?? 2003

  16. Science Fairs for Science Literacy

    Science.gov (United States)

    Mackey, Katherine; Culbertson, Timothy

    2014-03-01

    Scientific discovery, technological revolutions, and complex global challenges are commonplace in the modern era. People are bombarded with news about climate change, pandemics, and genetically modified organisms, and scientific literacy has never been more important than in the present day. Yet only 29% of American adults have sufficient understanding to be able to read science stories reported in the popular press [Miller, 2010], and American students consistently rank below other nations in math and science [National Center for Education Statistics, 2012].

  17. Estimates of land surface heat fluxes of the Mt. Everest region over the Tibetan Plateau utilizing ASTER data

    Science.gov (United States)

    Han, Cunbo; Ma, Yaoming; Chen, Xuelong; Su, Zhongbo

    2016-02-01

    Regional land surface albedo, land surface temperature, net radiation flux, ground heat flux, sensible heat flux, and latent heat flux were derived in the Mt. Everest area utilizing topographical enhanced surface energy balance system (TESEBS) model and nine scenes of ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) data under clear-sky and in-situ measurements at the QOMS station (the Qomolangma Station for Atmospheric Environmental Observation and Research, Chinese Academy of Sciences). The parameterization schemes for diffused and reflected downward shortwave radiation flux of the TESEBS model were improved by introducing the parameters sky-view factor (SVF) and terrain configuration factor (Ct). Then, a so-called C-correction method for land surface albedo was coupled into the TESEBS model to reduce the influences of topography. After topographical correction, the albedo of the dark tilted surface facing away from the Sun was compensated and albedo of the brightness surface facing the Sun was restrained. The downward shortwave radiation flux was broken down into three components including solar direct radiation flux, solar diffused radiation flux, and reflected solar radiation flux by surrounding terrain. The solar diffused radiation flux ranges from about 30 to 60 W/m2 at the satellite passing time on 6 January 2008. The reflected solar radiation flux changes from 0 to more than 100 W/m2 in the area covered by glaciers and snows. Thus, it is important to take the topographical effects into account in estimation of surface radiation balance in the mountainous area, especially in the glacier area. The retrieved land surface parameters, land surface radiation balance components, and the land surface energy balance components were evaluated by the field measurements in the QOMS station. The estimated results were very close to the in-situ observations with low mean bias errors, low root mean square errors and high correlation coefficients

  18. EU Development of High Heat Flux Components

    International Nuclear Information System (INIS)

    Linke, J.; Lorenzetto, P.; Majerus, P.; Merola, M.; Pitzer, D.; Roedig, M.

    2005-01-01

    The development of plasma facing components for next step fusion devices in Europe is strongly focused to ITER. Here a wide spectrum of different design options for the divertor target and the first wall have been investigated with tungsten, CFC, and beryllium armor. Electron beam simulation experiments have been used to determine the performance of high heat flux components under ITER specific thermal loads. Beside thermal fatigue loads with power density levels up to 20 MWm -2 , off-normal events are a serious concern for the lifetime of plasma facing components. These phenomena are expected to occur on a time scale of a few milliseconds (plasma disruptions) or several hundred milliseconds (vertical displacement events) and have been identified as a major source for the production of neutron activated metallic or tritium enriched carbon dust which is of serious importance from a safety point of view.The irradiation induced material degradation is another critical concern for future D-T-burning fusion devices. In ITER the integrated neutron fluence to the first wall and the divertor armour will remain in the order of 1 dpa and 0.7 dpa, respectively. This value is low compared to future commercial fusion reactors; nevertheless, a nonnegligible degradation of the materials has been detected, both for mechanical and thermal properties, in particular for the thermal conductivity of carbon based materials. Beside the degradation of individual material properties, the high heat flux performance of actively cooled plasma facing components has been investigated under ITER specific thermal and neutron loads

  19. Coordinates for Representing Radiation Belt Particle Flux

    Science.gov (United States)

    Roederer, Juan G.; Lejosne, Solène

    2018-02-01

    Fifty years have passed since the parameter "L-star" was introduced in geomagnetically trapped particle dynamics. It is thus timely to review the use of adiabatic theory in present-day studies of the radiation belts, with the intention of helping to prevent common misinterpretations and the frequent confusion between concepts like "distance to the equatorial point of a field line," McIlwain's L-value, and the trapped particle's adiabatic L* parameter. And too often do we miss in the recent literature a proper discussion of the extent to which some observed time and space signatures of particle flux could simply be due to changes in magnetospheric field, especially insofar as off-equatorial particles are concerned. We present a brief review on the history of radiation belt parameterization, some "recipes" on how to compute adiabatic parameters, and we illustrate our points with a real event in which magnetospheric disturbance is shown to adiabatically affect the particle fluxes measured onboard the Van Allen Probes.

  20. Regulation of flux through metabolic cycles

    International Nuclear Information System (INIS)

    Walsh, K.

    1984-01-01

    The branchpoint of the tricarboxylic acid and glyoxylate shunt was characterized in the intact organism by a multidimensional approach. Theory and methodology were developed to determine velocities for the net flow of carbon through the major steps of acetate metabolism in E. coli. Rates were assigned based on the 13 C-NMR spectrum of intracellular glutamate, measured rates of substrate incorporation into end products, the constituent composition of E. coli and a series of conservation equations which described the system at steady state. The in vivo fluxes through the branchpoint of the tricarboxylic acid and glyoxylate cycles were compared to rates calculated from the kinetic constants of the branchpoint enzymes and the intracellular concentrations of their substrates. These studies elucidated the role of isocitrate dehydrogenase phosphorylation in the Krebs cycle and led to the development of a generalized mathematical description of the sensitivity of branchpoints to regulatory control. This theoretical analysis was termed the branchpoint effect and it describes conditions which result in large changes in the flux through an enzyme even though that enzyme is not subject to direct regulatory control. The theoretical and experimental characterization of this system provided a framework to study the effects of enzyme overproduction and underproduction on metabolic processes in the cell. An in vivo method was developed to determine the extent to which an enzyme catalyzes a rate-controlling reaction. The enzyme chosen for this study was citrate synthase

  1. Neutron activation analysis: Modelling studies to improve the neutron flux of Americium–Beryllium source

    Directory of Open Access Journals (Sweden)

    Abdessamad Didi

    2017-06-01

    Full Text Available Americium–beryllium (Am-Be; n, γ is a neutron emitting source used in various research fields such as chemistry, physics, geology, archaeology, medicine, and environmental monitoring, as well as in the forensic sciences. It is a mobile source of neutron activity (20 Ci, yielding a small thermal neutron flux that is water moderated. The aim of this study is to develop a model to increase the neutron thermal flux of a source such as Am-Be. This study achieved multiple advantageous results: primarily, it will help us perform neutron activation analysis. Next, it will give us the opportunity to produce radio-elements with short half-lives. Am-Be single and multisource (5 sources experiments were performed within an irradiation facility with a paraffin moderator. The resulting models mainly increase the thermal neutron flux compared to the traditional method with water moderator.

  2. Exploring science through science fiction

    CERN Document Server

    Luokkala, Barry B

    2014-01-01

    How does Einstein’s description of space and time compare with Dr. Who? Can James Bond really escape from an armor-plated railroad car by cutting through the floor with a laser concealed in a wristwatch? What would it take to create a fully-intelligent android, such as Star Trek’s Commander Data? How might we discover intelligent civilizations on other planets in the galaxy? Is human teleportation possible? Will our technological society ever reach the point at which it becomes lawful to discriminate on the basis of genetic information, as in the movie GATTACA? Exploring Science Through Science Fiction addresses these and other interesting questions, using science fiction as a springboard for discussing fundamental science concepts and cutting-edge science research. The book is designed as a primary text for a college-level course which should appeal to students in the fine arts and humanities as well as to science and engineering students. It includes references to original research papers, landmark scie...

  3. A new disjunct eddy-covariance system for BVOC flux measurements - validation on CO2 and H2O fluxes

    Science.gov (United States)

    Baghi, R.; Durand, P.; Jambert, C.; Jarnot, C.; Delon, C.; Serça, D.; Striebig, N.; Ferlicoq, M.; Keravec, P.

    2012-12-01

    The disjunct eddy covariance (DEC) method is an interesting alternative to the conventional eddy covariance (EC) method because it allows the estimation of turbulent fluxes of species for which fast sensors are not available. We have developed and validated a new disjunct sampling system (called MEDEE). This system is built with chemically inert materials. Air samples are taken quickly and alternately in two cylindrical reservoirs, the internal pressures of which are regulated by a moving piston. The MEDEE system was designed to be operated either on the ground or aboard an aircraft. It is also compatible with most analysers since it transfers the air samples at a regulated pressure. To validate the system, DEC and EC measurements of CO2 and latent heat fluxes were performed concurrently during a field campaign. EC fluxes were first compared to simulated DEC (SDEC) fluxes and then to actual DEC fluxes. Both the simulated and actual DEC fluxes showed a good agreement with EC fluxes in terms of correlation. The determination coefficients (R2) were 0.93 and 0.91 for DEC and SDEC latent heat fluxes, respectively. For DEC and SDEC CO2 fluxes R2 was 0.69 in both cases. The conditions of low fluxes experienced during the campaign impaired the comparison of the different techniques especially for CO2 flux measurements. Linear regression analysis showed an 14% underestimation of DEC fluxes for both CO2 and latent heat compared to EC fluxes. A first field campaign, focusing on biogenic volatile organic compound (BVOC) emissions, was carried out to measure isoprene fluxes above a downy oak (Quercus Pubescens) forest in the south-east of France. The measured standard emission rate was in the lower range of reported values in earlier studies. Further analysis will be conducted through ground-based and airborne campaigns in the coming years.

  4. Science Fiction on Film.

    Science.gov (United States)

    Burmester, David

    1985-01-01

    Reviews science fiction films used in a science fiction class. Discusses feature films, short science fiction films, short story adaptations, original science fiction pieces and factual science films that enrich literature. (EL)

  5. Progress in surface and membrane science

    CERN Document Server

    Cadenhead, D A

    1981-01-01

    Progress in Surface and Membrane Science, Volume 14 covers the advances in the study of surface and membrane science. The book discusses statistical thermodynamics of monolayer adsorption from gas and liquid mixtures on homogeneous and heterogeneous solid surfaces; and the structure of the boundary layers of liquids and its influence on the mass transfer in fine pores. The text then describes the coupling of ionic and non-electrolyte fluxes in ion selective membranes; the electrocatalytic properties of matalloporphins at the interface; and the adsorption from binary gas and liquid phases. Phas

  6. Bay in Flux: Marine Climate Impacts, Art and Tablet App Design

    Science.gov (United States)

    Kintisch, E. S.

    2012-12-01

    Bay in Flux is a year-long experimental effort to design and develop interactive tablet computer apps exploring the marine impacts of climate change. The goal is to convey, visualize and enliven scientific ideas around this topic, while engaging a broad audience through the design of interactive content. Pioneering new models of scientist-artist collaborations are a central part of the effort as well. The project begins with an innovative studio class at the Rhode Island School of Design (RISD) called Bay in Flux, taught in the Fall 2012 semester. Its three instructor team includes two artist-designers and one science reporter, with active collaborations from affiliated marine scientists. The subject matter focus is the Narragansett Bay, which has shown physical, chemical and ecological impacts of climate change, along with the ongoing efforts of researchers to explain and characterize it. In exploring this rich story, we intend to innovate pioneering means of handling narrative material on interactive e-books, enable data collection by citizen scientists or devise game-like simulations to enable audiences to explore and understand complex natural systems. The lessons we seek to learn in this project include: how to effectively encourage collaborations between scientists and designers around digital design; how to pioneer new and compelling ways to tell science-based nonfiction stories on tablets; and how art and design students with no scientific training can engage with complex scientific content effectively. The project will also challenge us to think about the tablet computer not only as a data output device -- in which the user reads, watches, or interacts with provided content -- but also as a dynamic and ideal tool for mobile data input, enabling citizen science projects and novel connections between working researchers and the public. The intended audience could include high school students or older audiences who currently eschew science journalism. HTML5

  7. Network science

    CERN Document Server

    Barabasi, Albert-Laszlo

    2016-01-01

    Networks are everywhere, from the Internet, to social networks, and the genetic networks that determine our biological existence. Illustrated throughout in full colour, this pioneering textbook, spanning a wide range of topics from physics to computer science, engineering, economics and the social sciences, introduces network science to an interdisciplinary audience. From the origins of the six degrees of separation to explaining why networks are robust to random failures, the author explores how viruses like Ebola and H1N1 spread, and why it is that our friends have more friends than we do. Using numerous real-world examples, this innovatively designed text includes clear delineation between undergraduate and graduate level material. The mathematical formulas and derivations are included within Advanced Topics sections, enabling use at a range of levels. Extensive online resources, including films and software for network analysis, make this a multifaceted companion for anyone with an interest in network sci...

  8. CO2 Flux Inversion Error Analyses for Future Active Space CO2 Missions like ASCENDS

    Science.gov (United States)

    Baker, D. F.; Kawa, S. R.; Rayner, P. J.; Browell, E. V.; Menzies, R. T.; Abshire, J. B.

    2011-12-01

    We assess the ability of different proposed CO2 lidar measurement approaches to constrain surface CO2 fluxes, as part of the development of science requirements for NASA's ASCENDS mission. Observing system simulation experiments (OSSEs) are performed for different overall measurement uncertainty levels and vertical weightings to determine what designs will yield useful new information on the global carbon cycle. The OSSEs are based on a variational data assimilation method that models the measurements at the time and location they occur with minimal averaging and solves for the surface fluxes at regional spatial scales. Measurements are simulated using the PCTM off-line atmospheric transport model driven by GEOS5 analysis data (winds and vertical mixing parameters) and forced by realistic modeled CO2 fluxes. Both day- and night-side fluxes are estimated in weekly blocks at 4.5°x6° resolution (lat/lon) using a full year of simulated data. Error estimates are computed by direct comparison to the known truth; only random errors in the measurements and assumed flux prior are considered here. Relative measurement uncertainties and vertical averaging kernels have been derived for lidar measurements made using CO2 absorption lines in the 1.57 and 2.06 micron bands using realistic assumptions about clouds, aerosols, and surface reflectivity taken from CALIPSO and MODIS. Two measurement cases are considered for the 1.57 μm band, one using a vertical weighting function weighted to the mid- to lower troposphere, and one combining this with a function peaking near the tropopause. A third case is considered for measurements in the 2.06 μm band, with a vertical weighting peaking strongly near the surface. For each of these cases, three overall measurement uncertainty levels are examined (tied to reference uncertainties of 1.0, 0.5, and 0.2 ppm (1σ) at Railroad Valley, Nevada). OSSEs with simple measurement biases are run to test how the random-error-only findings hold in

  9. Flux Pinning and AC Loss in Second Generation High Temperature Superconductor Wires

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, Mariappan Parans [ORNL; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York

    2007-01-01

    Major advances have been made in the last 18 years in high-temperature superconductor (HTS) reserach and development, resulting in increased use of HTS materials in commerical and pre-commercial electric-power applications. This new and important book addresses the issues related to flux pinning, AC losses and thick YBCO film growth. Written by top most scientists in the world, it presents the current status and issues related to YBCO coated conductors and the need for further fundamental materials science work in YBCO coated conductor. It will be a useful handbook for years to come.

  10. Fluxes of biogenic volatile organic compounds above temperate Norway spruce forest of the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Juráň, Stanislav; Pallozi, E.; Guidolotti, G.; Fares, S.; Šigut, Ladislav; Calfapietra, Carlo; Alivernini, A.; Savi, F.; Večeřová, Kristýna; Křůmal, Kamil; Večeřa, Zbyněk; Urban, Otmar

    2017-01-01

    Roč. 232, JAN (2017), s. 500-513 ISSN 0168-1923 R&D Projects: GA MŠk(CZ) LO1415; GA MŠk(CZ) LD13031; GA MŠk(CZ) LM2015061; GA ČR(CZ) GA13-28093S Institutional support: RVO:67179843 ; RVO:68081715 Keywords : Monoterpenes * Isoprene * Proton-transfer-reaction-time-of-flight mass spectrometry (PTR-TOF-MS) * Fluxes * Lagrangian model * MEGAN Subject RIV: EH - Ecology, Behaviour; CB - Analytical Chemistry, Separation (UIACH-O) OBOR OECD: Environmental sciences (social aspects to be 5.7); Analytical chemistry (UIACH-O) Impact factor: 3.887, year: 2016

  11. Feasibility study of fast swept divertor strike point suppressing transient heat fluxes in big tokamaks.

    Czech Academy of Sciences Publication Activity Database

    Horáček, Jan; Cunningham, G.; Entler, Slavomír; Dobias, P.; Duban, R.; Imríšek, Martin; Markovič, Tomáš; Havlíček, Josef; Enikeev, R.

    2017-01-01

    Roč. 123, November (2017), s. 646-649 ISSN 0920-3796. [SOFT 2016: Symposium on Fusion Technology /29./. Prague, 05.09.2016-09.09.2016] R&D Projects: GA ČR(CZ) GA16-14228S; GA MŠk(CZ) LM2015045; GA MŠk(CZ) 8D15001; GA MŠk LG14002 Institutional support: RVO:61389021 Keywords : DEMO * ELM * Divertor * Heat flux * Tokamak Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 1.319, year: 2016 http://www.sciencedirect.com/science/article/pii/S0920379617300376

  12. Variability in concentrations and fluxes of methane in the Indian estuaries

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, G.D.; Sarma, V.V.S.S.

    and properties: Northern Gulf of Mexico. Geo-Marine Letters 10: 209-220. Alongi D.M. 2009. Energetics of Mangroves. Springer Science, Business Media B.V., New York, United States of America (ISBN- 13: 978-1402042706). 13    Bange, H. W., U.H. Bartell, S...-84.                  18    Estuary Size Latitude (0N) Longitude (0E) Surface Area (km2) Annual discharge (m3 s-1)& Salinity DO-Sat (%) POC (µM) CH4 (nM) CH4 Saturation (x103%) Flux- W92 (µmol m-2d-1) Rivers Flowing towards Bay...

  13. Coupling multipoint flux mixed finite element methodswith continuous Galerkin methods for poroelasticity

    KAUST Repository

    Wheeler, Mary

    2013-11-16

    We study the numerical approximation on irregular domains with general grids of the system of poroelasticity, which describes fluid flow in deformable porous media. The flow equation is discretized by a multipoint flux mixed finite element method and the displacements are approximated by a continuous Galerkin finite element method. First-order convergence in space and time is established in appropriate norms for the pressure, velocity, and displacement. Numerical results are presented that illustrate the behavior of the method. © Springer Science+Business Media Dordrecht 2013.

  14. Nonlinear Science

    CERN Document Server

    Yoshida, Zensho

    2010-01-01

    This book gives a general, basic understanding of the mathematical structure "nonlinearity" that lies in the depths of complex systems. Analyzing the heterogeneity that the prefix "non" represents with respect to notions such as the linear space, integrability and scale hierarchy, "nonlinear science" is explained as a challenge of deconstruction of the modern sciences. This book is not a technical guide to teach mathematical tools of nonlinear analysis, nor a zoology of so-called nonlinear phenomena. By critically analyzing the structure of linear theories, and cl

  15. Surface renewal: an advanced micrometeorological method for measuring and processing field-scale energy flux density data.

    Science.gov (United States)

    McElrone, Andrew J; Shapland, Thomas M; Calderon, Arturo; Fitzmaurice, Li; Paw U, Kyaw Tha; Snyder, Richard L

    2013-12-12

    Advanced micrometeorological methods have become increasingly important in soil, crop, and environmental sciences. For many scientists without formal training in atmospheric science, these techniques are relatively inaccessible. Surface renewal and other flux measurement methods require an understanding of boundary layer meteorology and extensive training in instrumentation and multiple data management programs. To improve accessibility of these techniques, we describe the underlying theory of surface renewal measurements, demonstrate how to set up a field station for surface renewal with eddy covariance calibration, and utilize our open-source turnkey data logger program to perform flux data acquisition and processing. The new turnkey program returns to the user a simple data table with the corrected fluxes and quality control parameters, and eliminates the need for researchers to shuttle between multiple processing programs to obtain the final flux data. An example of data generated from these measurements demonstrates how crop water use is measured with this technique. The output information is useful to growers for making irrigation decisions in a variety of agricultural ecosystems. These stations are currently deployed in numerous field experiments by researchers in our group and the California Department of Water Resources in the following crops: rice, wine and raisin grape vineyards, alfalfa, almond, walnut, peach, lemon, avocado, and corn.

  16. Initiation of CMEs by Magnetic Flux Emergence

    Indian Academy of Sciences (India)

    Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately.

  17. Models of Flux Tubes from Constrained Relaxation

    Indian Academy of Sciences (India)

    Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately.

  18. A scintillating fission detector for neutron flux measurements

    Energy Technology Data Exchange (ETDEWEB)

    Stange, Sy [Los Alamos National Laboratory; Esch, Ernst I [Los Alamos National Laboratory; Burgett, Eric A [Los Alamos National Laboratory; May, Iain [Los Alamos National Laboratory; Muenchausen, Ross E [Los Alamos National Laboratory; Taw, Felicia [Los Alamos National Laboratory; Tovesson, Fredrik K [Los Alamos National Laboratory

    2010-01-01

    Neutron flux monitors are commonly used for a variety of nuclear physics applications. A scintillating neutron detector, consisting of a liquid scintillator loaded with fissionable material, has been developed, characterized, and tested in the beam line at the Los Alamos Neutron Science Center, and shows a significant improvement in neutron sensitivity compared with a conventional fission chamber. Recent research on nanocomposite-based scintillators for gamma-ray detection indicates that this approach can be extended to load nanoparticles of fissionable material into a scintillating matrix, with up to three orders of magnitude higher loading than typical fission chambers. This will result in a rugged, cost-efficient detector with high efficiency, a short signal rise time, and the ability to be used in low neutron-flux environments. Initial efforts to utilize the luminescence of uranyl oxide to eliminate the need for wavelength-shifting dyes were unsuccessful. Excitation of uranyl compounds has been reported at wavelengths ranging from 266 nm to 532 nm. However, neither the 300 nm emission of toluene, nor the 350 nm emission of PPO, nor the 410 nm emission of POPOP resulted in significant excitation of and emission by uranyl oxide. As indicated by UV/visible spectroscopy, light emitted at these wavelengths was absorbed by the colored solution. {sup 235}U remains the most attractive candidate for a fissionable scintillator, due to its high fission cross-section and lack of a threshold fission energy, but all solutions containing molecular uranium compounds will be colored, most more highly than the U{sup 6+} compounds used here. Research is therefore continuing toward the fabrication of uranium nanoparticles, in which, due to Rayleigh scattering, the coloration should be less pronounced. The characterization of the thorium-loaded liquid scintillator and the fabrication of the 100 mL detectors for use at LANSCE demonstrated the feasibility of loading fissionable

  19. Tracking heat flux sensors for concentrating solar applications

    Science.gov (United States)

    Andraka, Charles E; Diver, Jr., Richard B

    2013-06-11

    Innovative tracking heat flux sensors located at or near the solar collector's focus for centering the concentrated image on a receiver assembly. With flux sensors mounted near a receiver's aperture, the flux gradient near the focus of a dish or trough collector can be used to precisely position the focused solar flux on the receiver. The heat flux sensors comprise two closely-coupled thermocouple junctions with opposing electrical polarity that are separated by a thermal resistor. This arrangement creates an electrical signal proportional to heat flux intensity, and largely independent of temperature. The sensors are thermally grounded to allow a temperature difference to develop across the thermal resistor, and are cooled by a heat sink to maintain an acceptable operating temperature.

  20. Updates from the AmeriFlux Management Project Tech Team

    Science.gov (United States)

    Biraud, S.; Chan, S.; Dengel, S.; Polonik, P.; Hanson, C. V.; Billesbach, D. P.; Torn, M. S.

    2017-12-01

    The goal of AmeriFlux is to develop a network of long-term flux sites for quantifying and understanding the role of the terrestrial biosphere in global climate and environmental change. The AmeriFlux Management Program (AMP) Tech Team at LBNL strengthens the AmeriFlux Network by (1) standardizing operational practices, (2) developing calibration and maintenance routines, and (3) setting clear data quality goals. In this poster we will present results and recent progress in three areas: IRGA intercomparison experiment in cooperation with UC Davis, and main manufacturers of sensors used in the AmeriFlux network (LI-COR, Picarro, and Campbell Scientific). Gill sonic anemometers characterization in collaboration with John Frank and Bill Massman (US Forest Service) following the discovery of a significant firmware problem in commonly used Gill Sonic anemometer, Unmanned aerial systems (UAS), and sensors systematically used at AmeriFlux sites to improve site characterization.

  1. Gap filling strategies for long term energy flux data sets

    DEFF Research Database (Denmark)

    Falge, E.; Baldocchi, D.; Olson, R.

    2001-01-01

    At present a network of over 100 field sites are measuring carbon dioxide, water vapor and sensible heat fluxes between the biosphere and atmosphere, on a nearly continuous basis. Gaps in the long term measurements of evaporation and sensible heat flux must be filled before these data can be used...... for hydrological and meteorological applications. We adapted methods of gap filling for NEE (net ecosystem exchange of carbon) to energy fluxes and applied them to data sets available from the EUROFLUX and AmeriFlux eddy covariance databases. The average data coverage for the sites selected was 69% and 75......% for latent heat (lambdaE) and sensible heat (H). The methods were based on mean diurnal variations (half-hourly binned means of fluxes based on previous and subsequent days, MDV) and look-up tables for fluxes during assorted meteorological conditions (LookUp), and the impact of different gap filling methods...

  2. The homogeneous property and flux splitting in gas dynamics

    Science.gov (United States)

    Lerat, A.

    The homogeneous property of fluxes in gas dynamics is investigated, and its consequences concerning the flux splitting introduced by Steger and Warming (1981) are examined. It is shown that, for any hyperbolic system w sub t + f(w) sub x = 0 which satisfies the homogeneous property, the flux f(w) can be expressed in terms of the eigenvalues and eigenvectors of the matrix A(w) = df(w)/dw. This same result is also found to hold for the split fluxes f(+)(w) and f(-)(w). The problem of the validity of flux splitting is studied using these results. Three applications of flux splitting are then considered. The first application concerns uncentered schemes and particularly a precise analysis of their stability, the second is connected with a method for correcting the dispersive error of second-order accurate schemes, and the third deals with a nonreflective boundary condition.

  3. Generalized flux states of the t-J model

    International Nuclear Information System (INIS)

    Nori, F.; Abrahams, E.; Zimanyi, G.T.

    1990-01-01

    We investigate certain generalized flux phases arising in a mean-field approach to the t-J model. First, we establish that the energy of noninteracting electrons moving in a uniform magnetic field has an absolute minimum as a function of the flux at exactly one flux quantum per particle. Using this result, we show that if the hard-core nature of the hole bosons is taken into account, then the slave-boson mean-field approximation for the t-J Hamiltonian allows for a solution where both the spinons and the holons experience an average flux of one flux quantum per particle. This enables them to achieve the lowest possible energy within the manifold of spatially uniform flux states. In the case of the continuum model, this is possible only for certain fractional fillings and we speculate that the system may react to this frustration effect by phase separation

  4. Cadmium filtered neutron flux determination. Comparison of activation methods

    International Nuclear Information System (INIS)

    Ollui-Mboulou, Magloire.

    1979-01-01

    Neutron fluxes under cadmium filters are determined by the cadmium ratio and sandwich activation methods. The thermal neutron flux levels obtained with 7 detectors of different kinds: In, Au, Ag, W, Co, Mn, Zn are compared. The cadmium ratio method was used in locations for which the epithermal and thermal neutron flux ratio are quite different. By irradiating materials under different thicknesses of cadmium it was possible to establish experimental curves from which the flux depression factors for intermediate neutrons may be determined whatever the thickness of the filter used. Whereas the cadmium ratio method can only measure the mean flux above the cadmium cut-off energy the sandwich method enables the flux value to be determined in a narrow band around the resonance energy of each detector used [fr

  5. Flux of granular particles through a shaken sieve plate

    Science.gov (United States)

    Wen, Pingping; Zheng, Ning; Nian, Junwei; Li, Liangsheng; Shi, Qingfan

    2015-01-01

    We experimentally investigate a discharging flux of granular particles through a sieve plate subject to vertical vibrations. The mean mass flux shows a non-monotonic relation with the vibration strength. High-speed photography reveals that two stages, the free flight of the particles’ bulk over the plate and the adhesion of the particles’ bulk with the plate, alternately appear, where only the adhesion stage contributes to the flow. With two independent methods, we then measure the adhesion time under different vibration conditions, and define an adhesion flux. The adhesion flux monotonically increases with increasing vibration strength. By rescaling the adhesion flux, we find that the adhesion flux is approximately determined by the peak vibration velocity of the shaker. The conclusion is examined with other sieve geometries. PMID:26056080

  6. A Novel Flux Linkage Indirect Measurement for Switched Reluctance Motor

    Science.gov (United States)

    Li, Pang; Zhang, Lei; Yu, Yue

    2017-05-01

    This paper presents a indirect detection system of flux linkage characteristic of switched reluctance motor based on dsPACE, fixed rotor position by mechanical indexing for Static flux linkage detection, the phase windings is excited by the step voltage signal, the voltage and phase current are collected real -time, and calculate flux linkage. The advantages of the method is that the parameters are optimized by ControlDesk, the flux linkage detection model is built by Simulink, no writing program, simple, easy implementation. An 1.5kw three-phase 12/8 SRM experimental prototype was constructed, the detection results of the Static flux linkage and dynamic flux linkage verified its validity and feasibility.

  7. Dynamic Flux Balance Analysis Using DFBAlab.

    Science.gov (United States)

    Gomez, Jose Alberto; Barton, Paul I

    2018-01-01

    Bioprocesses are of critical importance in several industries such as the food and pharmaceutical industries. Despite their importance and widespread application, bioprocess models remain rather simplistic and based on unstructured models. These simple models have limitations, making it very difficult to model complex bioprocesses. With dynamic flux balance analysis (DFBA) more comprehensive bioprocess models can be obtained. DFBA simulations are difficult to carry out because they result in dynamic systems with linear programs embedded. Therefore, the use of DFBA as a modeling tool has been limited. With DFBAlab, a MATLAB code that performs efficient and reliable DFBA simulations, the use of DFBA as a modeling tool has become more accessible. Here, we illustrate with an example how to implement bioprocess models in DFBAlab.

  8. SEED BANKS FOR MAGNETIC FLUX COMPRESSION GENERATORS

    Energy Technology Data Exchange (ETDEWEB)

    Fulkerson, E S

    2008-05-14

    In recent years the Lawrence Livermore National Laboratory (LLNL) has been conducting experiments that require pulsed high currents to be delivered into inductive loads. The loads fall into two categories (1) pulsed high field magnets and (2) the input stage of Magnetic Flux Compression Generators (MFCG). Three capacitor banks of increasing energy storage and controls sophistication have been designed and constructed to drive these loads. One bank was developed for the magnet driving application (20kV {approx} 30kJ maximum stored energy.) Two banks where constructed as MFCG seed banks (12kV {approx} 43kJ and 26kV {approx} 450kJ). This paper will describe the design of each bank including switching, controls, circuit protection and safety.

  9. Is inflation from unwinding fluxes IIB?

    Energy Technology Data Exchange (ETDEWEB)

    Gautason, Fridrik Freyr [Instituut voor Theoretische Fysica, K.University Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium); Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS,Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Schillo, Marjorie; Riet, Thomas Van [Instituut voor Theoretische Fysica, K.University Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium)

    2017-03-07

    In this paper we argue that the mechanism of unwinding inflation is naturally present in warped compactifications of type IIB string theory with local throats. The unwinding of flux is caused by its annihilation against branes. The resulting inflaton potential is linear with periodic modulations. We initiate an analysis of the inflationary dynamics and cosmological observables, which are highly constrained by moduli stabilization. For the simplified model of single-Kähler Calabi-Yau spaces we find that many, though not all of the consistency constraints can be satisfied. Particularly, in this simple model geometric constraints are in tension with obtaining the observed amplitude of the scalar power spectrum. However, we do find 60 efolds of inflation with a trans-Planckian field excursion which offers the hope that slightly more complicated models can lead to a fully consistent explicit construction of large field inflation of this kind.

  10. Analyzer of neutron flux in real time

    International Nuclear Information System (INIS)

    Rojas S, A.S.; Carrillo M, R.A.; Balderas, E.G.

    1999-01-01

    With base in the study of the real signals of neutron flux of instability events occurred in the Laguna Verde nuclear power plant where the nucleus oscillation phenomena of the reactor are in the 0 to 2.5 Hz range, it has been seen the possibility about the development a surveillance and diagnostic equipment capable to analyze in real time the behavior of nucleus in this frequencies range. An important method for surveillance the stability of the reactor nucleus is the use of the Power spectral density which allows to determine the frequencies and amplitudes contained in the signals. It is used an instrument carried out by LabVIEW graphic programming with a data acquisition card of 16 channels which works at Windows 95/98 environment. (Author)

  11. Parametric amplification by coupled flux qubits

    Energy Technology Data Exchange (ETDEWEB)

    Rehák, M.; Neilinger, P.; Grajcar, M. [Department of Experimental Physics, Comenius University, SK-84248 Bratislava (Slovakia); Institute of Physics, Slovak Academy of Science, 845 11 Bratislava (Slovakia); Oelsner, G.; Hübner, U.; Meyer, H.-G. [Leibniz Institute of Photonic Technology, P.O. Box 100239, D-07702 Jena (Germany); Il' ichev, E. [Leibniz Institute of Photonic Technology, P.O. Box 100239, D-07702 Jena (Germany); Novosibirsk State Technical University, 20 K. Marx Ave., 630092 Novosibirsk (Russian Federation)

    2014-04-21

    We report parametric amplification of a microwave signal in a Kerr medium formed from superconducting qubits. Two mutually coupled flux qubits, embedded in the current antinode of a superconducting coplanar waveguide resonator, are used as a nonlinear element. Shared Josephson junctions provide the qubit-resonator coupling, resulting in a device with a tunable Kerr constant (up to 3 × 10{sup −3}) and a measured gain of about 20 dB. This arrangement represents a unit cell which can be straightforwardly extended to a quasi one-dimensional quantum metamaterial with large tunable Kerr nonlinearity, providing a basis for implementation of wide-band travelling wave parametric amplifiers.

  12. Understanding Magnetic Flux Leakage signals from gouges

    Energy Technology Data Exchange (ETDEWEB)

    Clapham, Lynann; Babbar, Vijay; Dien Chen, Jian [Applied Magnetics Group, Department of Physics, Queen' s University, Kingston, Ontario (Canada)], email: lynann@physics.queensu.ca; Alexander, Chris [Stress Engineering Services Inc., Houston, Texas (United States)

    2010-07-01

    Mechanical damage in pipelines is an important issue as it can lead to immediate or delayed failures. The magnetic flux leakage (MFL) method can be used to locate and characterize mechanical damage in pipelines. The purpose of this study is to get a better understanding of how MFL signals arise from pipeline gouges. Experimental MFL measurements were carried out on X60 grade pipe sections where a defect set of 10 gouges had been introduced; measurements were conducted on both internal and external pipe wall surface. Results showed that deformation and residual stress due to a gouge are mostly situated at the outer wall surface and that MFL measurements detected it from the inside and a model was developed to account for MFL axial dipole signal. This study brought new information on MFL signals and further work will be undertaken to completely understand how MFL signals arise from pipe gouge.

  13. Fluxes of carbon dioxide at Thetford Forest

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available The Thetford Project (1968–1976 was a keystone project for the newly established Institute of Hydrology. Its primary objective was to elucidate the processes underlying evaporation of transpired water and intercepted rainfall from plantation forest, so as to explain hydrological observations that more water was apparently returned to the atmosphere from plantations than from grassland and heathland. The primary approach was to determine the fluxes of water vapour from a stand of Scots pine, situated within a larger area of plantations of Scots and Corsican pine, in Thetford Forest, East Anglia, UK, using the Bowen ratio approach. In 1976, advantage was taken of the methodology developed to add measurement of profiles of carbon dioxide concentration so as to enable the fluxes of CO2 also to be calculated. A team from Aberdeen and Edinburgh Universities collected 914 hours of 8-point CO2 concentration profiles, largely between dawn and dusk, on days from March to October, and the data from an "elite" data set of 710 hours have been analysed. In conditions of moderate temperature (−1 with high solar irradiance (>500 W m−2, CO2 uptake reached relatively high rates for pine of up to 20 µmol m−2 s−1 in the middle of the day. This rate of CO2 uptake is higher than has been recently found for four Scots pine forests in continental Europe during July 1997. However, the year of 1976 was exceptionally hot and dry, with air temperatures reaching 30°C and the water deficit in the top 3 m of soil at the site of 152 mm by August. Air temperatures of over 25°C led to large specific humidity deficits, approaching 20 g kg−1, and associated severe reductions in CO2 uptake, as well as in evaporation. However, when specific humidity deficits dropped below c. 15 g kg−1 on succeeding days, generally as a result of lower air temperatures rather than lower solar irradiance, there was rapid recovery in both uptake and evaporation, thus indicating that

  14. Trace gas fluxes from northern peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Moore, T. [McGill Univ., Montreal (Canada). Geography Dept.

    1996-12-31

    Peatlands cover large areas in northern environments: 1.1, 0.1 and 1.7 x 10{sup 4} km{sup 2} in Canada, Finland and the former Soviet Union, respectively. Interest has been generated into the role these extensive areas of peatlands play in controlling the chemistry of the atmosphere. In particular, it has become established that peatlands can be a source of methane (CH{sub 4}) and nitrous oxide (N{sub 2}O), and a sink of carbon dioxide (CO{sub 2}), the latter through the rates of plant production exceeding the rate of decomposition of plant material and peat. In this presentation the recent advances in trace gas flux measurements in northern peatlands are presented. (16 refs.)

  15. Magnetic flux trapping in superconducting niobium

    CERN Document Server

    Benvenuti, Cristoforo; Campisi, I E; Darriulat, Pierre; Durand, C; Peck, M A; Russo, R; Valente, A M

    1997-01-01

    In a systematic study of the RF response of superconducting niobium cavities operated in their fundamental TM010 mode at 1.5 GHz, magnetic flux trapping has been used as a tool to diagnose the presenc e of pinning centres. In addition to bulk niobium cavities the study covers copper cavities, the inner walls of which are coated with 1.5 µm thick niobium films grown by magnetron sputtering in a nobl e gas atmosphere. The use of different gases (Xe, Kr, Ar and Ne) or gas mixtures has made it possible to vary the concentration of noble gas atoms in the films. Film contamination is characterised by an electron mean free path l calculated from the results of systematic measurements of the penetration depth at T = 0 K, l0, and from RRR measurements made on samples prepared under similar conditions as the cavity films.

  16. Mass fluxes in the Canary Basin

    Science.gov (United States)

    Machín, F.; Hernández-Guerra, A.; Pelegrí, J. L.

    2006-08-01

    Ocean studies in the 1970s provided an improved knowledge of the coastal upwelling region off NW Africa while in the 1980s and 1990s they led to a good description of the open ocean flow patterns in the Canary Basin. It was not until the late 1990s that major research addressed the open-coastal ocean coupled response. Here we examine the mean and seasonal circulation patterns in the Canary Basin with data from four hydrographic cruises carried out in the region between Cape Ghir, Madeira Island, and the Canary Islands. We apply an inverse box model to an ocean divided into 14 layers, with several layers representing each water mass or stratum, to obtain mass fluxes consistent with the thermal wind equation. An optimum flow description is obtained using conservation of mass, salt and heat anomaly, biologically corrected oxygen, and silicate, and allowing for Ekman transport in the surface layer and dianeutral mixing between adjacent layers. The deep waters show no predominant flow direction while the intermediate waters display localized southward flowing Mediterranean Water far from shore, and northward flowing Antarctic Intermediate Water near the continental slope, specially in the passage between the eastern Canary Islands and the African slope. The mean upper-thermocline Canary Current, composed of North Atlantic Central Water, flows south with an open-ocean branch transporting about 3 ± 1 Sv (1 Sv = 10 6 m 3 s -1 ≅ 10 9 kg s -1), and an upwelling-related branch near the continental slope carrying 1 ± 0.3 Sv. The seasonal transport by the open-ocean branch intensifies and moves offshore from spring to fall (2.8 ± 1.2 Sv in spring, 2.9 ± 1.1 Sv in summer, and 4.5 ± 1.2 Sv in fall), while it carries its lowest southward mass flux in winter (1.7 ± 1.0 Sv), possibly as a result of a migration offshore the sampled region. Upwelling-related southward flow is present in spring and summer (1.9 ± 0.1 Sv and 2.4 ± 0.1 Sv, respectively) while in fall and winter

  17. Axial flux data for fuel measurement

    Energy Technology Data Exchange (ETDEWEB)

    Popovich, R.P.

    1964-02-11

    A survey of the PITA-18 nonpoisonous spline program was conducted in conjunction with a study to determine the best method of eliminating the variability of axial flux on the fuel performance parameter, q. The results of this survey and the conclusions reached in the rupture coefficient study were found to be inter-dependent such that both are presented in this report. The data from the PITA-18 nonpoisonous spline program, as received, is the output of the NOLA-2 computer program. One quantity of interest is the rupture potential relative to a cosine, commonly referred to as the relative rupture potential. As programmed, the relative rupture potential, which was derived by applying the rupture model to individual fuel elements, might be expected to vary linearly with the rupture rate. The use of the relative rupture potential was studied over the period of July 1962 through December 1963. The results of this study are presented.

  18. Permanent-magnet switched-flux machine

    Science.gov (United States)

    Trzynadlowski, Andrzej M.; Qin, Ling

    2012-02-21

    A permanent-magnet switched-flux (PMSF) device has an outer rotor mounted to a shaft about a central axis extending axially through the PMSF device. First and second pluralities of permanent-magnets (PMs) are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the outer rotor. An inner stator is coupled to the shaft and has i) a stator core having a core axis co-axial with the central axis; and ii) first and second pluralities of stator poles mounted in first and second circles, radially outwardly from the stator core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.

  19. FFTF [Fast Flux Test Facility] management

    International Nuclear Information System (INIS)

    Bennett, C.L.

    1986-11-01

    Fuel Management at the Fast Flux Test Facility (FFTF) involves more than just the usual ex-core and in-core management of standard fuel and non-fuel components between storage locations and within the core since it is primarily an irradiation test facility. This mission involves testing an ever increasing variety of fueled and non-fueled experiments, each having unique requirements on the reactor core as well as having its own individual impact on the reload design. This paper describes the fuel management process used by the Westinghouse Hanford Company Core Engineering group that has led to the successful reload design of nine operating cycles and the irradiation of over 120 tests

  20. HFBR handbook, 1992: High flux beam reactor

    International Nuclear Information System (INIS)

    Axe, J.D.; Greenberg, R.

    1992-10-01

    Welcome to the High Flux Beam Reactor (HFBR), one of the world premier neutron research facilities. This manual is intended primarily to acquaint outside users (and new Brookhaven staff members) with (almost) everything they need to know to work at the HFBR and to help make the stay at Brookhaven pleasant as well as profitable. Safety Training Programs to comply with US Department of Energy (DOE) mandates are in progress at BNL. There are several safety training requirements which must be met before users can obtain unescorted access to the HFBR. The Reactor Division has prepared specific safety training manuals which are to be sent to experimenters well in advance of their expected arrival at BNL to conduct experiments. Please familiarize yourself with this material and carefully pay strict attention to all the safety and security procedures that are in force at the HFBR. Not only your safety, but the continued operation of the facility, depends upon compliance

  1. Permanent-magnet switched-flux machine

    Science.gov (United States)

    Trzynadlowski, Andrzej M.; Qin, Ling

    2010-01-12

    A permanent-magnet switched-flux (PMSF) device has a ferromagnetic outer stator mounted to a shaft about a central axis extending axially through the PMSF device. Pluralities of top and bottom stator poles are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the ferromagnetic outer stator. A ferromagnetic inner rotor is coupled to the shaft and has i) a rotor core having a core axis co-axial with the central axis; and ii) first and second discs having respective outer edges with first and second pluralities of permanent magnets (PMs) mounted in first and second circles, radially outwardly from the rotor core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.

  2. Line width of Josephson flux flow oscillators

    DEFF Research Database (Denmark)

    Koshelets, V.P.; Dmitriev, P.N.; Sobolev, A.S.

    2002-01-01

    A combination of wide-band electronic tunability and moderate free-running line width makes the Josephson flux flow oscillator (FFO) a perfect on-chip local oscillator for integrated submillimeter-wave SIS receivers. The possibility of FFO phase locking at all frequencies of interest has...... to be proven before one initiates real FFO applications. To achieve this goal a comprehensive set of line width measurements of the FFO operating in different regimes has been performed. FFOs with tapered shape have been successfully implemented in order to avoid the superfine resonant structure with voltage...... spacing of about 20 nV and extremely low differential resistance, recently observed in the IVC of the standard rectangular geometry. The obtained results have been compared with existing theories and FFO models in order to understand and possibly eliminate excess noise in the FFO. The intrinsic line width...

  3. Compressed magnetic flux amplifier with capacitive load

    International Nuclear Information System (INIS)

    Stuetzer, O.M.

    1980-03-01

    A first-order analysis is presented for a compressed magnetic flux (CMF) current amplifier working into a load with a capacitive component. Since the purpose of the investigation was to gain a general understanding of the arrangement, a number of approximations and limitations were accepted. The inductance of the transducer varies with time; the inductance/resistance/capacitance (LRC) circuit therefore is parametric and solutions are different for the stable regime (high C), the oscillation regime (low C), and the transition case. Solutions and performance depend strongly on circuit boundary conditions, i.e., energization of the circuit by either an injected current or by an applied capacitor charge. The behavior of current and energy amplification for the various cases are discussed in detail. A number of experiments with small CMF devices showed that the first-order theory presented predicts transducer performance well in the linear regime

  4. Freshwater flux to Sermilik Fjord, SE Greenland

    Directory of Open Access Journals (Sweden)

    S. H. Mernild

    2010-10-01

    Full Text Available Terrestrial inputs of freshwater flux to Sermilik Fjord, SE Greenland, were estimated, indicating ice discharge to be the dominant source of freshwater. A freshwater flux of 40.4 ± 4.9×109 m3 y−1 was found (1999–2008, with an 85% contribution originated from ice discharge (65% alone from Helheim Glacier, 11% from terrestrial surface runoff (from melt water and rain, 3% from precipitation at the fjord surface area, and 1% from subglacial geothermal and frictional melting due to basal ice motion. The results demonstrate the dominance of ice discharge as a primary mechanism for delivering freshwater to Sermilik Fjord. Time series of ice discharge for Helheim Glacier, Midgård Glacier, and Fenris Glacier were calculated from satellite-derived average surface velocity, glacier width, and estimated ice thickness, and fluctuations in terrestrial surface freshwater runoff were simulated based on observed meteorological data. These simulations were compared and bias corrected against independent glacier catchment runoff observations. Modeled runoff to Sermilik Fjord was variable, ranging from 2.9 ± 0.4×109 m3 y−1 in 1999 to 5.9 ± 0.9×109 m3 y−1 in 2005. The sub-catchment runoff of the Helheim Glacier region accounted for 25% of the total runoff to Sermilik Fjord. The runoff distribution from the different sub-catchments suggested a strong influence from the spatial variation in glacier coverage, indicating high runoff volumes, where glacier cover was present at low elevations.

  5. DOWNWARD CATASTROPHE OF SOLAR MAGNETIC FLUX ROPES

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Quanhao; Wang, Yuming; Hu, Youqiu; Liu, Rui, E-mail: zhangqh@mail.ustc.edu.cn [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026 (China)

    2016-07-10

    2.5-dimensional time-dependent ideal magnetohydrodynamic (MHD) models in Cartesian coordinates were used in previous studies to seek MHD equilibria involving a magnetic flux rope embedded in a bipolar, partially open background field. As demonstrated by these studies, the equilibrium solutions of the system are separated into two branches: the flux rope sticks to the photosphere for solutions at the lower branch but is suspended in the corona for those at the upper branch. Moreover, a solution originally at the lower branch jumps to the upper, as the related control parameter increases and reaches a critical value, and the associated jump is here referred to as an upward catastrophe. The present paper advances these studies in three aspects. First, the magnetic field is changed to be force-free; the system still experiences an upward catastrophe with an increase in each control parameter. Second, under the force-free approximation, there also exists a downward catastrophe, characterized by the jump of a solution from the upper branch to the lower. Both catastrophes are irreversible processes connecting the two branches of equilibrium solutions so as to form a cycle. Finally, the magnetic energy in the numerical domain is calculated. It is found that there exists a magnetic energy release for both catastrophes. The Ampère's force, which vanishes everywhere for force-free fields, appears only during the catastrophes and does positive work, which serves as a major mechanism for the energy release. The implications of the downward catastrophe and its relevance to solar activities are briefly discussed.

  6. DOWNWARD CATASTROPHE OF SOLAR MAGNETIC FLUX ROPES

    International Nuclear Information System (INIS)

    Zhang, Quanhao; Wang, Yuming; Hu, Youqiu; Liu, Rui

    2016-01-01

    2.5-dimensional time-dependent ideal magnetohydrodynamic (MHD) models in Cartesian coordinates were used in previous studies to seek MHD equilibria involving a magnetic flux rope embedded in a bipolar, partially open background field. As demonstrated by these studies, the equilibrium solutions of the system are separated into two branches: the flux rope sticks to the photosphere for solutions at the lower branch but is suspended in the corona for those at the upper branch. Moreover, a solution originally at the lower branch jumps to the upper, as the related control parameter increases and reaches a critical value, and the associated jump is here referred to as an upward catastrophe. The present paper advances these studies in three aspects. First, the magnetic field is changed to be force-free; the system still experiences an upward catastrophe with an increase in each control parameter. Second, under the force-free approximation, there also exists a downward catastrophe, characterized by the jump of a solution from the upper branch to the lower. Both catastrophes are irreversible processes connecting the two branches of equilibrium solutions so as to form a cycle. Finally, the magnetic energy in the numerical domain is calculated. It is found that there exists a magnetic energy release for both catastrophes. The Ampère's force, which vanishes everywhere for force-free fields, appears only during the catastrophes and does positive work, which serves as a major mechanism for the energy release. The implications of the downward catastrophe and its relevance to solar activities are briefly discussed.

  7. The fate of unstable gauge flux compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, C.P. [McMaster Univ., Hamilton, ON (Canada). Dept. of Physics and Astronomy]|[Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada); Parameswaran, S.L. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Zavala, I. [Bonn Univ. (Germany). Bethe Center for Theoretical Physics and Physikalisches Inst.

    2008-12-15

    Fluxes are widely used to stabilise extra dimensions, but the supporting monopolelike configurations are often unstable, particularly if they arise as gauge flux within a non-abelian gauge sector. We here seek the endpoint geometries to which this instability leads, focussing on the simplest concrete examples: sphere-monopole compactifications in six dimensions. Without gravity most monopoles in non-abelian gauge groups are unstable, decaying into the unique stable monopole in the same topological class. We show that the same is true in Einstein-YM systems, with the new twist that the decay leads to a shrinkage in the size of the extra dimensions and curves the non-compact directions: in D dimensions a Mink{sub D-2} x S{sub 2} geometry supported by an unstable monopole relaxes to AdS{sub D-2} x S{sub 2}, with the endpoint sphere smaller than the initial one. For supergravity the situation is more complicated because the dilaton obstructs such a simple evolution. The endpoint instead acquires a dilaton gradient, thereby breaking some of the spacetime symmetries. For 6D supergravity we argue that it is the 4D symmetries that break, and examine several candidates for the endpoint geometry. By using the trick of dimensional oxidation it is possible to recast the supergravity system as a higher-dimensional Einstein-YM monopole, allowing understanding of this system to guide us to the corresponding endpoint. The result is a Kasner-like geometry conformal to Mink{sub 4} times S{sub 2}, with nontrivial conformal factor and dilaton breaking the maximal 4D symmetry and generating a singularity. Yet the resulting configuration has a lower potential energy than did the initial one, and is perturbatively stable, making it a sensible candidate endpoint for the evolution. (orig.)

  8. Magnetic flux noise in copper oxide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, M.J.

    1991-11-01

    Magnetic flux noise and flux creep in thin films and single crystals of YBa{sub 2}Cu{sub 3}O{sub 7-x}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x}, Tl{sub 2}Ca{sub 2}Ba{sub 2}Cu{sub 3}O{sub x}, and TlCa{sub 2}Ba{sub 2}Cu{sub 3}O{sub x} are measured with a superconducting quantum interference device (SQUID). The noise power spectrum generally scales as 1/f (f is frequency) from 1 Hz to 1 kHz, increases with temperature, and decreases in higher-quality films. It is proportional to the magnetic field B in which the sample is cooled, at least in the range 0.1 mT < B < 3 mT. A model of thermally activated vortex motion is developed which explains the dependence of the noise on frequency, temperature, current, and applied magnetic field. The pinning potential is idealized as an ensemble of double wells, each with a different activation energy separating the two states. From the noise measurements, this model yields the distribution of pinning energies in the samples, the vortex hopping distance, the number density of mobile vortices, and the restoring force on a vortex at a typical pinning site. The distribution of pinning energies in YBa{sub 2}Cu{sub 3}O{sub 7-x} shows a broad peak below 0.1 eV. The small ambient magnetic field, and the detection of noise even in the absence of a driving force, insure that the measured pinning energies are characteristic of isolated vortices near thermal equilibrium. The observed vortex density in fields much less than 0.1 mT is too large to be explained by the ambient field, suggesting a mechanism intrinsic to the sample which produces trapped vortices.

  9. Parameter optimization for surface flux transport models

    Science.gov (United States)

    Whitbread, T.; Yeates, A. R.; Muñoz-Jaramillo, A.; Petrie, G. J. D.

    2017-11-01

    Accurate prediction of solar activity calls for precise calibration of solar cycle models. Consequently we aim to find optimal parameters for models which describe the physical processes on the solar surface, which in turn act as proxies for what occurs in the interior and provide source terms for coronal models. We use a genetic algorithm to optimize surface flux transport models using National Solar Observatory (NSO) magnetogram data for Solar Cycle 23. This is applied to both a 1D model that inserts new magnetic flux in the form of idealized bipolar magnetic regions, and also to a 2D model that assimilates specific shapes of real active regions. The genetic algorithm searches for parameter sets (meridional flow speed and profile, supergranular diffusivity, initial magnetic field, and radial decay time) that produce the best fit between observed and simulated butterfly diagrams, weighted by a latitude-dependent error structure which reflects uncertainty in observations. Due to the easily adaptable nature of the 2D model, the optimization process is repeated for Cycles 21, 22, and 24 in order to analyse cycle-to-cycle variation of the optimal solution. We find that the ranges and optimal solutions for the various regimes are in reasonable agreement with results from the literature, both theoretical and observational. The optimal meridional flow profiles for each regime are almost entirely within observational bounds determined by magnetic feature tracking, with the 2D model being able to accommodate the mean observed profile more successfully. Differences between models appear to be important in deciding values for the diffusive and decay terms. In like fashion, differences in the behaviours of different solar cycles lead to contrasts in parameters defining the meridional flow and initial field strength.

  10. On geodynamo integrations conserving momentum flux

    Science.gov (United States)

    Wu, C.; Roberts, P. H.

    2012-12-01

    The equations governing the geodynamo are most often integrated by representing the magnetic field and fluid velocity by toroidal and poloidal scalars (for example, MAG code [1]). This procedure does not automatically conserve the momentum flux. The results can, particularly for flows with large shear, introduce significant errors, unless the viscosity is artificially increased. We describe a method that evades this difficulty, by solving the momentum equation directly while properly conserving momentum. It finds pressure by FFT and cyclic reduction, and integrates the governing equations on overlapping grids so avoiding the pole problem. The number of operations per time step is proportional to N3 where N is proportional to the number of grid points in each direction. This contrasts with the order N4 operations of standard spectral transform methods. The method is easily parallelized. It can also be easily adapted to schemes such as the Weighted Essentially Non-Oscillatory (WENO) method [2], a flux based procedure based on upwinding that is numerically stable even for zero explicit viscosity. The method has been successfully used to investigate the generation of magnetic fields by flows confined to spheroidal containers and driven by precessional and librational forcing [3, 4]. For spherical systems it satisfies dynamo benchmarks [5]. [1] MAG, http://www.geodynamics.org/cig/software/mag [2] Liu, XD, Osher, S and Chan, T, Weighted Essentially Nonoscillatory Schemes, J. Computational Physics, 115, 200-212, 1994. [3] Wu, CC and Roberts, PH, On a dynamo driven by topographic precession, Geophysical & Astrophysical Fluid Dynamics, 103, 467-501, (DOI: 10.1080/03091920903311788), 2009. [4] Wu, CC and Roberts, PH, On a dynamo driven topographically by longitudinal libration, Geophysical & Astrophysical Fluid Dynamics, DOI:10.1080/03091929.2012.682990, 2012. [5] Christensen, U, et al., A numerical dynamo benchmark, Phys. Earth Planet Int., 128, 25-34, 2001.

  11. CO2 and heat fluxes in a recently clear-cut spruce forest in European Russia: experimental and modeling studies

    Science.gov (United States)

    Mamkin, Vadim; Kurbatova, Julia; Avilov, Vitaly; Mukhartova, Yulia; Krupenko, Alexander; Ivanov, Dmitry; Levashova, Natalia; Olchev, Alexander

    2017-04-01

    Ecosystem carbon dioxide, energy, and water fluxes were measured using eddy covariance and portable chambers in a fresh clear-cut surrounded by a mixed spruce-birch-aspen forest in the boreal zone of European Russia. Measurements were initiated in spring 2016 following timber harvest and continued for seven months until the end of October. The influence of surrounding forest on air flow and turbulent fluxes within the clear-cut were examined using a process-based two-dimensional (2D) hydrodynamic turbulent exchange model. Clear-cut was a permanent source of CO2 to the atmosphere. During the period the mean daily latent (LE) and sensible (H) heat fluxes were very similar and the Bowen ratio (β=H/LE) averaged about 1.0. During the late spring and summer months the net ecosystem exchange of CO2 (NEE) remained slightly positive following onset of vegetation growth, while β was changing in the range from 0.6 to 4.0. There was strong diurnal variability in NEE, LE and H over the measurement period that was governed by solar radiation and temperature as well as the leaf area index (LAI) of regrown vegetation. Modeled vertical CO2 and H2O fluxes along a transect that crossed the clear-cut and coincided with the dominate wind direction showed that the clear-cut strongly influenced turbulent fluxes within the atmospheric surface layer. Furthermore, modeled atmospheric dynamics suggested that the clear-cut had a large influence on turbulent fluxes in the downwind forest, but little impact on the upwind side. An aggregated approach including field measurements and process-based models can be used to estimate energy, water and carbon dioxide fluxes in non-uniform forest landscapes. This study was supported by a grant from the Russian Science Foundation (14-14-00956).

  12. Flux transformers made of commercial high critical temperature superconducting wires.

    Science.gov (United States)

    Dyvorne, H; Scola, J; Fermon, C; Jacquinot, J F; Pannetier-Lecoeur, M

    2008-02-01

    We have designed flux transformers made of commercial BiSCCO tapes closed by soldering with normal metal. The magnetic field transfer function of the flux transformer was calculated as a function of the resistance of the soldered contacts. The performances of different kinds of wires were investigated for signal delocalization and gradiometry. We also estimated the noise introduced by the resistance and showed that the flux transformer can be used efficiently for weak magnetic field detection down to 1 Hz.

  13. Exotic orientifolds in non-geometric flux cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Damian, Cesar; Loaiza-Brito, Oscar [Departamento de Física, Universidad de Guanajuato, C.P. 37150, León, Guanajuato (Mexico)

    2013-07-23

    We report on the existence of a stable de Sitter vacum in Type IIB non-geometric string compactification on an isotropic tours with orientifold 3-planes in the presence of odd integer 3-form fluxes. These fluxes yields the presence of exotic orientifold 3-planes increasing the size of the flux configuration space. We also find that there exist suitable conditions for multi-field inflation driven by the Kähler and axio-dilaton moduli.

  14. The higher order flux mapping method in large size PHWRs

    International Nuclear Information System (INIS)

    Kulkarni, A.K.; Balaraman, V.; Purandare, H.D.

    1997-01-01

    A new higher order method is proposed for obtaining flux map using single set of expansion mode. In this procedure, one can make use of the difference between predicted value of detector reading and their actual values for determining the strength of local fluxes around detector site. The local fluxes are arising due to constant perturbation changes (both extrinsic and intrinsic) taking place in the reactor. (author)

  15. Hadron fluxes in inner parts of LHC detectors

    International Nuclear Information System (INIS)

    Aarnio, P.A.; Huhtinen, M.

    1993-01-01

    We have simulated neutron and charged hadron fluxes inside the tracking cavity and around the electromagnetic calorimeter in a typical LHC detector geometry using the Fluka92 code. We find a strong dependence of the fluxes on electromagnetic calorimeter materials. We observe high neutron fluxes in calorimeter endcaps, while charged hadrons are found to be the major cause of displacement damage at an inner silicon tracker. (orig.)

  16. Strong flux of low-energy neutrons produced by thunderstorms.

    Science.gov (United States)

    Gurevich, A V; Antonova, V P; Chubenko, A P; Karashtin, A N; Mitko, G G; Ptitsyn, M O; Ryabov, V A; Shepetov, A L; Shlyugaev, Yu V; Vildanova, L I; Zybin, K P

    2012-03-23

    We report here for the first time about the registration of an extraordinary high flux of low-energy neutrons generated during thunderstorms. The measured neutron count rate enhancements are directly connected with thunderstorm discharges. The low-energy neutron flux value obtained in our work is a challenge for the photonuclear channel of neutron generation in thunderstorm: the estimated value of the needed high-energy γ-ray flux is about 3 orders of magnitude higher than that one observed.

  17. Experimental tests of FTE theories. [Flux Transfer Event

    Science.gov (United States)

    Sonnerup, B. U. O.

    1988-01-01

    A brief overview is presented of a number of qualitative geometrical models as well as simulation models of flux transfer events (FTEs) and an attempt is made to identify critical observational tests that would help discriminate between these models. These tests are concerned with flux tube orientation, speed and structure. Available single and multiple spacecraft observations are discussed in the context of these tests. Particular attention is given to the problem of determining flux-tube orientation and speed from a single spacecraft.

  18. Cognitive Science.

    Science.gov (United States)

    Cocking, Rodney R.; Mestre, Jose P.

    The focus of this paper is on cognitive science as a model for understanding the application of human skills toward effective problem-solving. Sections include: (1) "Introduction" (discussing information processing framework, expert-novice distinctions, schema theory, and learning process); (2) "Application: The Expert-Novice…

  19. Talking Science

    Science.gov (United States)

    Eley, Alison

    2011-01-01

    The Talking Science project initially involved three secondary schools and eight of their feeder primary schools in the London Borough of Richmond Upon Thames. The project created, trialled and evaluated a set of key stage 2/3 transition materials for children moving from primary to secondary school, using argument as a teaching and learning…

  20. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- .... Kaullysing et al. also present a field note on coral-eating gastropods observed around Mauritius. ... and decision making in the field of coral reef studies and management in Mauritius, while contributing.

  1. Marine Science

    African Journals Online (AJOL)

    Micro-phytoplankton density, C-biomass and diversity. Tides and zones had significant effects on the over- all total C-biomass of total micro-phytoplankton and bacillariophytes, and concentrations of ...... to environmental parameters in cage culture area of Sepanggar Bay, Malaysia. Estuarine Coastal and. Shelf Science 80: ...

  2. Marine Science

    African Journals Online (AJOL)

    The journal publishes original research articles dealing with all aspects of marine science and coastal manage- ment. Topics include, but are not limited to: theoretical studies, oceanography, marine biology and ecology, fisheries, recovery and restoration processes, legal and institutional frameworks, and interactions/ ...

  3. Science Notes.

    Science.gov (United States)

    School Science Review, 1990

    1990-01-01

    Presented are 25 science activities on colorations of prey, evolution, blood, physiology, nutrition, enzyme kinetics, leaf pigments, analytical chemistry, milk, proteins, fermentation, surface effects of liquids, magnetism, drug synthesis, solvents, wintergreen synthesis, chemical reactions, multicore cables, diffraction, air resistance,…

  4. Systems Science

    Science.gov (United States)

    Christakis, Alexander; Hammond, Debora; Jackson, Michael; Laszlo, Alexander; Mitroff, Ian; Snowden, Dave; Troncale, Len; Carr-Chellman, Alison; Spector, J. Michael; Wilson, Brent

    2013-01-01

    Scholars representing the field of systems science were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Alexander Christakis, Debora Hammond, Michael Jackson, Alexander Laszlo, Ian Mitroff, Dave…

  5. Marine Science

    African Journals Online (AJOL)

    fisheries, recovery and restoration processes, legal and institutional frameworks, and interactions/relationships between ... ISSN 0856-860X. Western Indian Ocean. J O U R N A L O F. Marine Science. Editorial Board. Serge ANDREFOUËT. France. Ranjeet BHAGOOLI. Mauritius ...... ence Technology, Rhodes, Greece.

  6. Science Smiles

    Indian Academy of Sciences (India)

    IAS Admin

    Page 1. 666. RESONANCE | August 2015. Science Smiles. Ayan Guha. Email for Correspondence: ionguha@gmail.com. Oduvai Gorge gives us one of the most remarkable stories of the past – the last chapter of the Earth's history, starting at the present day, right away back 2 million years.

  7. Science Smiles

    Indian Academy of Sciences (India)

    Page 1. 75. RESONANCE │ January 2011. BOOK │ REVIEW. Science Smiles. Ayan Guha. Email for Correspondence: ionguha@gmail.com. What if I say that all the people living in our United Netherlands are not as many as the animalcules living in this single drop of water.

  8. Science Smiles

    Indian Academy of Sciences (India)

    Page 1. Science Smiles. RKLaxman. I bought the plot to build my office. But the activists would not let me touch anything lest it should upset the ecological balance here. R -E-SO-N-A-N-C-E -, -Fe-b-ru-ary-19-9-S -----~-------------

  9. Skeptical Science.

    Science.gov (United States)

    Scott, Alan J.; Barnhart, Carolyn M.; Parejko, Ken S.; Schultz, Forrest S.; Schultz, Steven E.

    2001-01-01

    Discusses the legitimacy of teaching about astrology, extrasensory perception, UFOs, touch therapy, cloning dinosaurs, or any other unusual claims in the classroom. Suggests that bringing unusual claims to the science classroom is an opportunity to motivate students in the principles of scientific thought. (SAH)

  10. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high quality research ... PAHs are among the persistent organic pollutants that are a worldwide environmental ... combusted and petroleum products are used during boat/dhow making and servicing ...

  11. Actuarial Science.

    Science.gov (United States)

    Warren, Bette

    1982-01-01

    Details are provided of a program on actuarial training developed at the State University of New York (SUNY) at Binghamton through the Department of Mathematical Sciences. An outline of its operation, including a few statistics on students in the program, is included. (MP)

  12. Marine Science

    African Journals Online (AJOL)

    org/wio-journal-of-marine- science/ and AJOL ... The mangroves around Maputo city in Maputo Bay were studied to assess changes in forest cover area and the effect of cutting ..... factors on forest health condition has not yet been assessed.

  13. Organizational Science

    Science.gov (United States)

    Beriwal, Madhu; Clegg, Stewart; Collopy, Fred; McDaniel, Reuben, Jr.; Morgan, Gareth; Sutcliffe, Kathleen; Kaufman, Roger; Marker, Anthony; Selwyn, Neil

    2013-01-01

    Scholars representing the field of organizational science, broadly defined as including many fields--organizational behavior and development, management, workplace performance, and so on--were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might…

  14. Redirecting science

    International Nuclear Information System (INIS)

    Aaserud, F.

    1990-01-01

    This book contains the following chapters. Science policy and fund-raising up to 1934; The Copenhagen spirit at work, late 1920's to mid-1930s; The refugee problem, 1933 to 1935; Experimental biology, late 1920s to 1935; and Consolidation of the transition, 1935 to 1940

  15. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high quality research generated in the Western Indian Ocean (WIO) region, in particular on the sustainable use of coastal and marine resources. This is central to the goal of supporting and promoting.

  16. Science Notes.

    Science.gov (United States)

    Talbot, Chris; And Others

    1991-01-01

    Twenty science experiments are presented. Topics include recombinant DNA, physiology, nucleophiles, reactivity series, molar volume of gases, spreadsheets in chemistry, hydrogen bonding, composite materials, radioactive decay, magnetism, speed, charged particles, compression waves, heat transfer, Ursa Major, balloons, current, and expansion of…

  17. Boundless Science

    Science.gov (United States)

    Spilhaus, F.

    2009-04-01

    Our science is critical to understanding the future prospects for life. The laboratory for natural sciences encompasses our planet and reaches into the solar system. The forces of nature respect no boundaries. But, we who try to understand these forces are handicapped by national, political, language, religious, and other concocted barriers. These barriers limit both our effectiveness as scientists and our ability to reach those outside our community who need to know what we have uncovered about our environment. An unencumbered worldwide scientific community has been an objective with limited successes for too long. Action began in earnest after the first world war with the formation of the various scientific Unions and ICSU. Fifty years later Keith Runcorn initiated another approach, when he proposed what quickly became EGS and which has grown and evolved with the merger with EUG. To be truly effective we need to communicate and share comfortably with colleagues worldwide. Personal relationships and trust are required. We count on a high level of ethical behavior within our community. We individually must also be constantly vigilant for the encroachment of the manmade barriers that have held back science through time immemorial. Our scientific organizations cannot achieve this alone. They will facilitate, however, the onus is on each of us to reach out and form interlocking informal communities, which will bring our whole planet-wide community together at many overlapping levels. When we achieve this community, our science will more bountiful and better address the needs of human society.

  18. Science and anti-science

    CERN Document Server

    Holton, Gerald

    1997-01-01

    What is good science? What goal--if any--is the proper end of scientific activity? Is there a legitimating authority that scientists mayclaim? Howserious athreat are the anti-science movements? These questions have long been debated but, as Gerald Holton points out, every era must offer its own responses. This book examines these questions not in the abstract but shows their historic roots and the answers emerging from the scientific and political controversies of this century. Employing the case-study method and the concept of scientific thematathat he has pioneered, Holton displays the broad scope of his insight into the workings of science: from the influence of Ernst Mach on twentiethcentury physicists, biologists, psychologists, and other thinkers to the rhetorical strategies used in the work of Albert Einstein, Niels Bohr, and others; from the bickering between Thomas Jefferson and the U.S. Congress over the proper form of federal sponsorship of scientific research to philosophical debates since Oswald...

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

    Science.gov (United States)

    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

  20. Design Considerations of Permanent Magnet Transverse Flux Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Rasmussen, Peter Omand; Ritchie, Ewen

    2011-01-01

    Permanent magnet transverse flux machine (PMTFM) is well known for its high torque density and is interested in various direct-drive applications. Due to its complicated 3-D flux components, design and design optimization of a PMTFM is more difficult and time consuming than for radial flux...... electrical machines. This paper addresses two important design considerations for PMTFM—the influence of permanent magnet leakage flux, which plays an important role in the determination of machine output torque, and the leakage inductance. A new simple method to provide a quick estimation of the armature...

  1. Thin Film Heat Flux Sensors: Design and Methodology

    Science.gov (United States)

    Fralick, Gustave C.; Wrbanek, John D.

    2013-01-01

    Thin Film Heat Flux Sensors: Design and Methodology: (1) Heat flux is one of a number of parameters, together with pressure, temperature, flow, etc. of interest to engine designers and fluid dynamists, (2) The measurement of heat flux is of interest in directly determining the cooling requirements of hot section blades and vanes, and (3)In addition, if the surface and gas temperatures are known, the measurement of heat flux provides a value for the convective heat transfer coefficient that can be compared with the value provided by CFD codes.

  2. Validating modeled turbulent heat fluxes across large freshwater surfaces

    Science.gov (United States)

    Lofgren, B. M.; Fujisaki-Manome, A.; Gronewold, A.; Anderson, E. J.; Fitzpatrick, L.; Blanken, P.; Spence, C.; Lenters, J. D.; Xiao, C.; Charusambot, U.

    2017-12-01

    Turbulent fluxes of latent and sensible heat are important physical processes that influence the energy and water budgets of the Great Lakes. Validation and improvement of bulk flux algorithms to simulate these turbulent heat fluxes are critical for accurate prediction of hydrodynamics, water levels, weather, and climate over the region. Here we consider five heat flux algorithms from several model systems; the Finite-Volume Community Ocean Model, the Weather Research and Forecasting model, and the Large Lake Thermodynamics Model, which are used in research and operational environments and concentrate on different aspects of the Great Lakes' physical system, but interface at the lake surface. The heat flux algorithms were isolated from each model and driven by meteorological data from over-lake stations in the Great Lakes Evaporation Network. The simulation results were compared with eddy covariance flux measurements at the same stations. All models show the capacity to the seasonal cycle of the turbulent heat fluxes. Overall, the Coupled Ocean Atmosphere Response Experiment algorithm in FVCOM has the best agreement with eddy covariance measurements. Simulations with the other four algorithms are overall improved by updating the parameterization of roughness length scales of temperature and humidity. Agreement between modelled and observed fluxes notably varied with geographical locations of the stations. For example, at the Long Point station in Lake Erie, observed fluxes are likely influenced by the upwind land surface while the simulations do not take account of the land surface influence, and therefore the agreement is worse in general.

  3. Flux-limited diffusion models in radiation hydrodynamics

    International Nuclear Information System (INIS)

    Pomraning, G.C.; Szilard, R.H.

    1993-01-01

    The authors discuss certain flux-limited diffusion theories which approximately describe radiative transfer in the presence of steep spatial gradients. A new formulation is presented which generalizes a flux-limited description currently in widespread use for large radiation hydrodynamic calculations. This new formation allows more than one Case discrete mode to be described by a flux-limited diffusion equation. Such behavior is not extant in existing formulations. Numerical results predicted by these flux-limited diffusion models are presented for radiation penetration into an initially cold halfspace. 37 refs., 5 figs

  4. Critical heat flux, post dry-out and their augmentation

    International Nuclear Information System (INIS)

    Celata, G.P.; Mariani, A.

    1999-01-01

    The report shows the state of art review on the critical heat flux and the post-dryout heat transfer. The work, which is a merge of original researches carried out at the Institute of Thermal Fluid Dynamic of ENEA (National Agency for New Technology, Energy and the Environment) and a thorough review of the recent literature, is divided in four chapters: critical heat flux in subcooled flow boiling; critical heat flux in saturated flow boiling; post-dryout heat transfer; enhancement of critical heat flux and post-dryout heat transfer [it

  5. Actinide and Xenon reactivity effects in ATW high flux systems

    Energy Technology Data Exchange (ETDEWEB)

    Woosley, M. [Univ. of Virginia, Charlottesville, VA (United States); Olson, K.; Henderson, D.L. [Univ. of Wisconsin, Madison, WI (United States)] [and others

    1995-10-01

    In this paper, initial system reactivity response to flux changes caused by the actinides and xenon are investigated separately for a high flux ATW system. The maximum change in reactivity after a flux change due to the effect of the changing quantities of actinides is generally at least two orders of magnitude smaller than either the positive or negative reactivity effect associated with xenon after a shutdown or start-up. In any transient flux event, the reactivity response of the system to xenon will generally occlude the response due to the actinides.

  6. A Hybrid Excited Machine with Flux Barriers and Magnetic Bridges

    Directory of Open Access Journals (Sweden)

    Marcin Wardach

    2018-03-01

    Full Text Available In this paper, an U-shape flux barrier rotor concept for a hybrid excited synchronous machine with flux magnetic bridges fixed on the rotor is presented. Using 3D finite element analysis, the influence of axial flux bridges on the field-weakening and -strengthening characteristics, electromagnetic torque, no-load magnetic flux linkage, rotor iron losses and back electromotive force is shown. Three different rotor designs are analyzed. Furthermore, the field control characteristics depending on additional DC control coil currents are shown.

  7. Actinide and xenon reactivity effects in ATW high flux systems

    International Nuclear Information System (INIS)

    Woosley, M.; Olson, K.; Henderson, D. L.; Sailor, W. C.

    1995-01-01

    In this paper, initial system reactivity response to flux changes caused by the actinides and xenon are investigated separately for a high flux ATW system. The maximum change in reactivity after a flux change due to the effect of the changing quantities of actinides is generally at least two orders of magnitude smaller than either the positive or negative reactivity effect associated with xenon after a shutdown or start-up. In any transient flux event, the reactivity response of the system to xenon will generally occlude the response due to the actinides

  8. Actinide and Xenon reactivity effects in ATW high flux systems

    International Nuclear Information System (INIS)

    Woosley, M.; Olson, K.; Henderson, D.L.

    1995-01-01

    In this paper, initial system reactivity response to flux changes caused by the actinides and xenon are investigated separately for a high flux ATW system. The maximum change in reactivity after a flux change due to the effect of the changing quantities of actinides is generally at least two orders of magnitude smaller than either the positive or negative reactivity effect associated with xenon after a shutdown or start-up. In any transient flux event, the reactivity response of the system to xenon will generally occlude the response due to the actinides

  9. Vertical divergence of fogwater fluxes above a spruce forest

    Science.gov (United States)

    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.

  10. Caring Science or Science of Caring.

    Science.gov (United States)

    Turkel, Marian C; Watson, Jean; Giovannoni, Joseph

    2018-01-01

    The concepts caring science and science of caring have different meanings; however, they are often used interchangeably. The purpose of this paper is to present an overview of the synthesis of the scholarly literature on the definitions of the science of caring and caring science and to affirm the authors' perspective relating to the language of caring science. Caring science advances the epistemology and ontology of caring. Ideas related to caring science inquiry are presented, and the authors acknowledge the future of caring science as unitary caring science.

  11. Portraying Real Science in Science Communication

    Science.gov (United States)

    van Dijk, Esther M.

    2011-01-01

    In both formal and informal settings, not only science but also views on the nature of science are communicated. Although there probably is no singular nature shared by all fields of science, in the field of science education it is commonly assumed that on a certain level of generality there is a consensus on many features of science. In this…

  12. Consideration of critical heat flux margin prediction by subcooled or low quality critical heat flux correlations

    International Nuclear Information System (INIS)

    Hejzlar, P.; Todreas, N.E.

    1996-01-01

    The accurate prediction of the critical heat flux (CHF) margin which is a key design parameter in a variety of cooling and heating systems is of high importance. These margins are, for the low quality region, typically expressed in terms of critical heat flux ratios using the direct substitution method. Using a simple example of a heated tube, it is shown that CHF correlations of a certain type often used to predict CHF margins, expressed in this manner, may yield different results, strongly dependent on the correlation in use. It is argued that the application of the heat balance method to such correlations, which leads to expressing the CHF margins in terms of the critical power ratio, may be more appropriate. (orig.)

  13. Biotic, abiotic and management controls on methanol fluxes above a temperate mountain grassland

    Science.gov (United States)

    Hörtnagl, Lukas; Bamberger, Ines; Graus, Martin; Ruuskanen, Taina; Schnitzhofer, Ralf; Müller, Markus; Hansel, Armin; Wohlfahrt, Georg

    2010-05-01

    -hourly averages. As methanol is produced in expanding cell walls, the change in the measured green area index (?GAI) was used as a proxy for plant growth. However ?GAI was poorly correlated with methanol fluxes, possible explanations will be discussed. References: Davison, B., Brunner, A., Amman, C., Spirig, C., Jocher, M., Neftel, A. Cut-induced VOC emissions from agricultural grasslands. Plant Biol. 10, 76-85, 2008. Harley, P., Greenberg, J., Niinemets, Ü., and Guenther, A..: Environmental controls over methanol emission from leaves. Biogeosciences, 4, 1083-1099, 2007. Hüve, K., Christ, M., Kleist, E., Uerlings, R., Niinemets, Ü., Walter, A. and Wildt, J.: Simultaneous growth and emission measurements demonstrate an interactive control of methanol release by leaf expansion and stomata. doi:10.1093/jxb/erm038, Journal of Experimental Botany, 2007. Niinemets, Ü. and Reichstein, M.: Controls on the emission of plant volatiles through stomata: A sensitivity analysis. J. Geophys. Res., 108, 4211, doi:10.1029/2002JD002626, 2003. Niinemets, Ü., Loreto, F. and Reichstein, M.: Physiological and physicochemical controls on foliar volatile organic compound emissions. Trends in Plant Science,9, 2004. Wohlfahrt G., Haslwanter A., Hörtnagl L., Jasoni R.L., Fenstermaker L.F., Arnone J.A. III, Hammerle A. (2009) On the consequences of the energy imbalance for calculating surface conductance to water vapour. Agricultural and Forest Meteorology 149, 15561559.

  14. Combining soil and tree-stem flux measurements and soil gas profiles to understand CH4 pathways in Fagus sylvatica forests

    Czech Academy of Sciences Publication Activity Database

    Maier, M.; Macháčová, Kateřina; Lang, F.; Svobodová, Kateřina; Urban, Otmar

    2018-01-01

    Roč. 181, č. 1 (2018), s. 31-35 ISSN 1436-8730 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : ch4 * soil gas profile * gas flux * co2 * methanogenesis Subject RIV: ED - Physiology OBOR OECD: Plant science s, botany Impact factor: 2.102, year: 2016

  15. The Oceanic Flux Program: A three decade time-series of particle flux in the deep Sargasso Sea

    Science.gov (United States)

    Weber, J. C.; Conte, M. H.

    2010-12-01

    The Oceanic Flux Program (OFP), 75 km SE of Bermuda, is the longest running time-series of its kind. Initiated in 1978, the OFP has produced an unsurpassed, nearly continuous record of temporal variability in deep ocean fluxes, with a >90% temporal coverage at 3200m depth. The OFP, in conjunction with the co-located Bermuda-Atlantic Time Series (BATS) and the Bermuda Testbed Mooring (BTM) time-series, has provided key observations enabling detailed assessment of how seasonal and non-seasonal variability in the deep ocean is linked with the overlying physical and biogeochemical environment. This talk will focus on the short-term flux variability that overlies the seasonal flux pattern in the Sargasso Sea, emphasizing episodic extreme flux events. Extreme flux events are responsible for much of the year-to-year variability in mean annual flux and are most often observed during early winter and late spring when surface stratification is weak or transient. In addition to biological phenomena (e.g. salp blooms), passage of productive meso-scale features such as eddies, which alter surface water mixing characteristics and surface export fluxes, may initiate some extreme flux events. Yet other productive eddies show a minimal influence on the deep flux, underscoring the importance of upper ocean ecosystem structure and midwater processes on the coupling between the surface ocean environment and deep fluxes. Using key organic and inorganic tracers, causative processes that influence deep flux generation and the strength of the coupling with the surface ocean environment can be identified.

  16. Flux depression and the absolute measurement of the thermal neutron flux density

    International Nuclear Information System (INIS)

    Bensch, Friedrich.

    1977-01-01

    The thermal neutron flux depression in a diffusing medium by an absorbing foil has been treated in numerous papers. The results are re-examined in an attempt to find a uniform and physically meaningful representation of the 'activation correction'. This quantity can be split up into a combination of probabilities. Thus, it is possible to determine the activation correction for any moderator and foil material. Measurements confirm the utility of the concepts introduced

  17. Prediction of Metabolic Flux Distribution from Gene Expression Data Based on the Flux Minimization Principle

    Science.gov (United States)

    2014-11-14

    Saccharomyces cerevisiae , and wild-type and mutant Escherichia coli strains, our method achieved high prediction accuracy, as gauged by correlation...the aerobic growth of S. cerevisiae . We used experimental data collected by Lee et al., which included RNA-seq transcriptomic data and exchange flux...measurements of S. cerevisiae aerobically growing in chemostat cultures. This study provides data under two different growth conditions, i.e., glucose

  18. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.

    Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  19. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    2003-07-01

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  20. The Science in Science Fiction.

    Science.gov (United States)

    Nicholls, Peter, Ed.

    This 12-chapter book discusses the scientific facts behind the ideas included in the novels of Robert Heinlein, Isaac Asimov, Frederik Pohl, Arthur C. Clark and other science fiction writers. Areas explored in the first 11 chapters include: exploration of deep space; energy and exotic power sources; likelihood of extra-terrestrial life and the…