WorldWideScience

Sample records for water-bound material fluxes

  1. Water, bound and mobile

    Science.gov (United States)

    Resolving the global transpiration flux is critical to constraining global carbon cycle models because carbon uptake by photosynthesis in terrestrial plants (Gross Primary Productivity, GPP) is directly related to water lost through transpiration. Quantifying GPP globally is cha...

  2. Dynamics of water bound to crystalline cellulose

    Energy Technology Data Exchange (ETDEWEB)

    O’Neill, Hugh; Pingali, Sai Venkatesh; Petridis, Loukas; He, Junhong; Mamontov, Eugene; Hong, Liang; Urban, Volker; Evans, Barbara; Langan, Paul; Smith, Jeremy C.; Davison, Brian H.

    2017-09-19

    Interactions of water with cellulose are of both fundamental and technological importance. Here, we characterize the properties of water associated with cellulose using deuterium labeling, neutron scattering and molecular dynamics simulation. Quasi-elastic neutron scattering provided quantitative details about the dynamical relaxation processes that occur and was supported by structural characterization using small-angle neutron scattering and X-ray diffraction. We can unambiguously detect two populations of water associated with cellulose. The first is “non-freezing bound” water that gradually becomes mobile with increasing temperature and can be related to surface water. The second population is consistent with confined water that abruptly becomes mobile at ~260 K, and can be attributed to water that accumulates in the narrow spaces between the microfibrils. Quantitative analysis of the QENS data showed that, at 250 K, the water diffusion coefficient was 0.85 ± 0.04 × 10-10 m2sec-1 and increased to 1.77 ± 0.09 × 10-10 m2sec-1 at 265 K. MD simulations are in excellent agreement with the experiments and support the interpretation that water associated with cellulose exists in two dynamical populations. Our results provide clarity to previous work investigating the states of bound water and provide a new approach for probing water interactions with lignocellulose materials.

  3. Baseline high heat flux and plasma facing materials for fusion

    Science.gov (United States)

    Ueda, Y.; Schmid, K.; Balden, M.; Coenen, J. W.; Loewenhoff, Th.; Ito, A.; Hasegawa, A.; Hardie, C.; Porton, M.; Gilbert, M.

    2017-09-01

    In fusion reactors, surfaces of plasma facing components (PFCs) are exposed to high heat and particle flux. Tungsten and Copper alloys are primary candidates for plasma facing materials (PFMs) and coolant tube materials, respectively, mainly due to high thermal conductivity and, in the case of tungsten, its high melting point. In this paper, recent understandings and future issues on responses of tungsten and Cu alloys to fusion environments (high particle flux (including T and He), high heat flux, and high neutron doses) are reviewed. This review paper includes; Tritium retention in tungsten (K. Schmid and M. Balden), Impact of stationary and transient heat loads on tungsten (J.W. Coenen and Th. Loewenhoff), Helium effects on surface morphology of tungsten (Y. Ueda and A. Ito), Neutron radiation effects in tungsten (A. Hasegawa), and Copper and copper alloys development for high heat flux components (C. Hardie, M. Porton, and M. Gilbert).

  4. Materials compatibility and aging for flux and cleaner combinations

    Energy Technology Data Exchange (ETDEWEB)

    Archuleta, Kim M. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Piatt, Rochelle [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-01-01

    A materials study of high reliability electronics cleaning is presented here. In Phase 1, mixed type substrates underwent a condensed contaminants application to view a worst- case scenario for unremoved flux with cleaning agent residue for parts in a silicone oil filled environment. In Phase 2, fluxes applied to copper coupons and to printed wiring boards underwent gentle cleaning then accelerated aging in air at 65% humidity and 30 O C. Both sets were aged for 4 weeks. Contaminants were no-clean (ORL0), water soluble (ORH1 liquid and ORH0 paste), and rosin (RMA; ROL0) fluxes. Defluxing agents were water, solvents, and engineered aqueous defluxers. In the first phase, coupons had flux applied and heated, then were placed in vials of oil with a small amount of cleaning agent and additional coupons. In the second phase, pairs of copper coupons and PWB were hand soldered by application of each flux, using tin-lead solder in a strip across the coupon or a set of test components on the PWB. One of each pair was cleaned in each cleaning agent, the first with a typical clean, and the second with a brief clean. Ionic contamination residue was measured before accelerated aging. After aging, substrates were removed and a visual record of coupon damage made, from which a subjective rank was applied for comparison between the various flux and defluxer combinations; more corrosion equated to higher rank. The ORH1 water soluble flux resulted in the highest ranking in both phases, the RMA flux the least. For the first phase, in which flux and defluxer remained on coupons, the aqueous defluxers led to worse corrosion. The vapor phase cleaning agents resulted in the highest ranking in the second phase, in which there was no physical cleaning. Further study of cleaning and rinsing parameters will be required.

  5. 19 CFR 10.98 - Copper-bearing fluxing material.

    Science.gov (United States)

    2010-04-01

    ... consumption or warehouse, a declaration of the importer that the material is to be used for fluxing purposes... plant if to be used in a bonded smelting warehouse, or in accordance with §§ 151.52 through 151.55 of... Government chemist in accordance with the assay. (e) The management of the smelting or converting plant shall...

  6. Material gap membrane distillation: A new design for water vapor flux enhancement

    KAUST Repository

    Francis, Lijo

    2013-08-19

    A new module design for membrane distillation, namely material gap membrane distillation (MGMD), for seawater desalination has been proposed and successfully tested. It has been observed that employing appropriate materials between the membrane and the condensation plate in an air gap membrane distillation (AGMD) module enhanced the water vapor flux significantly. An increase in the water vapor flux of about 200-800% was observed by filling the gap with sand and DI water at various feed water temperatures. However, insulating materials such as polypropylene and polyurethane have no effect on the water vapor flux. The influence of material thickness and characteristics has also been investigated in this study. An increase in the water gap width from 9. mm to 13. mm increases the water vapor flux. An investigation on an AGMD and MGMD performance comparison, carried out using two different commercial membranes provided by different manufacturers, is also reported in this paper. © 2013 Elsevier B.V.

  7. Flux

    DEFF Research Database (Denmark)

    Ravn, Ib

    Med udgangspunkt i kompleksistetsforskning og studiet af selvorganiserende systemer beskriver lb Ravn den fysiske og biologiske evolution og menneskets udvikling. Han fortolker begreber som kultur, sprog, frihed, værdier, mening, smerte og det ondes problem i lyset af en procesbaseret ontologi...... 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...

  8. Non-Destructive Testing for the In Situ Assessment of the Ionic Flux in Cementitious Materials

    Science.gov (United States)

    Tittarelli, Francesca; Pierpaoli, Mattia; Giosuè, Chiara; Ruello, M. Letizia

    2017-08-01

    The study deals with the design, calibration and testing of a diffusive sampling probe for in situ assessment of ion mobility in binder-based matrix. In parallel, leaching texts were conducted to compare the ions release obtained under equilibrium condition with the dynamic flux induced by the diffusive sampling probe. The probe contains an ionic exchange resin that acts as sink, causing a re-supply of ions from the solid to the solution phase, and inducing diffusion fluxes from the mortar through a thin diffusion chamber. The flux depends on the quantity of mobile ions in the solid phase and on the exchanging rate from solid phase to solution. By means of the in situ sampling with this diffusive probe, information about the interaction of materials with the environment can be obtained. This information is very useful for the environmental impact assessment of the material and its durability.

  9. Development of advanced high heat flux and plasma-facing materials

    Science.gov (United States)

    Linsmeier, Ch.; Rieth, M.; Aktaa, J.; Chikada, T.; Hoffmann, A.; Hoffmann, J.; Houben, A.; Kurishita, H.; Jin, X.; Li, M.; Litnovsky, A.; Matsuo, S.; von Müller, A.; Nikolic, V.; Palacios, T.; Pippan, R.; Qu, D.; Reiser, J.; Riesch, J.; Shikama, T.; Stieglitz, R.; Weber, T.; Wurster, S.; You, J.-H.; Zhou, Z.

    2017-09-01

    Plasma-facing materials and components in a fusion reactor are the interface between the plasma and the material part. The operational conditions in this environment are probably the most challenging parameters for any material: high power loads and large particle and neutron fluxes are simultaneously impinging at their surfaces. To realize fusion in a tokamak or stellarator reactor, given the proven geometries and technological solutions, requires an improvement of the thermo-mechanical capabilities of currently available materials. In its first part this article describes the requirements and needs for new, advanced materials for the plasma-facing components. Starting points are capabilities and limitations of tungsten-based alloys and structurally stabilized materials. Furthermore, material requirements from the fusion-specific loading scenarios of a divertor in a water-cooled configuration are described, defining directions for the material development. Finally, safety requirements for a fusion reactor with its specific accident scenarios and their potential environmental impact lead to the definition of inherently passive materials, avoiding release of radioactive material through intrinsic material properties. The second part of this article demonstrates current material development lines answering the fusion-specific requirements for high heat flux materials. New composite materials, in particular fiber-reinforced and laminated structures, as well as mechanically alloyed tungsten materials, allow the extension of the thermo-mechanical operation space towards regions of extreme steady-state and transient loads. Self-passivating tungsten alloys, demonstrating favorable tungsten-like plasma-wall interaction behavior under normal operation conditions, are an intrinsic solution to otherwise catastrophic consequences of loss-of-coolant and air ingress events in a fusion reactor. Permeation barrier layers avoid the escape of tritium into structural and cooling

  10. Tidal day organic and inorganic material flux of ponds in the Liberty Island freshwater tidal wetland.

    Science.gov (United States)

    Lehman, Peggy W; Mayr, Shawn; Liu, Leji; Tang, Alison

    2015-01-01

    The loss of inorganic and organic material export and habitat produced by freshwater tidal wetlands is hypothesized to be an important contributing factor to the long-term decline in fishery production in San Francisco Estuary. However, due to the absence of freshwater tidal wetlands in the estuary, there is little information on the export of inorganic and organic carbon, nutrient or phytoplankton community biomass and the associated mechanisms. A single-day study was conducted to assess the potential contribution of two small vegetated ponds and one large open-water pond to the inorganic and organic material flux within the freshwater tidal wetland Liberty Island in San Francisco Estuary. The study consisted of an intensive tidal day (25.5 h) sampling program that measured the flux of inorganic and organic material at three ponds using continuous monitoring of flow, chlorophyll a, turbidity and salt combined with discrete measurements of phytoplankton community carbon, total and dissolved organic carbon and nutrient concentration at 1.5 h intervals. Vegetated ponds had greater material concentrations than the open water pond and, despite their small area, contributed up to 81% of the organic and 61% of the inorganic material flux of the wetland. Exchange between ponds was important to wetland flux. The small vegetated pond in the interior of the wetland contributed as much as 72-87% of the total organic carbon and chlorophyll a and 10% of the diatom flux of the wetland. Export of inorganic and organic material from the small vegetated ponds was facilitated by small-scale topography and tidal asymmetry that produced a 40% greater material export on ebb tide. The small vegetated ponds contrasted with the large open water pond, which imported 29-96% of the inorganic and 4-81% of the organic material into the wetland from the adjacent river. This study identified small vegetated ponds as an important source of inorganic and organic material to the wetland and the

  11. Carbon Flux of Down Woody Materials in Forests of the North Central United States

    Directory of Open Access Journals (Sweden)

    C. W. Woodall

    2010-01-01

    Full Text Available Across large scales, the carbon (C flux of down woody material (DWM detrital pools has largely been simulated based on forest stand attributes (e.g., stand age and forest type. The annual change in forest DWM C stocks and other attributes (e.g., size and decay class changes was assessed using a forest inventory in the north central United States to provide an empirical assessment of strategic-scale DWM C flux. Using DWM inventory data from the USDA Forest Service's Forest Inventory and Analysis program, DWM C stocks were found to be relatively static across the study region with an annual flux rate not statistically different from zero. Mean C flux rates across the study area were −0.25, −0.12, −0.01, and −0.04 (Mg/ha/yr for standing live trees, standing dead trees, coarse woody debris, and fine woody debris, respectively. Flux rates varied in their both magnitude and status (emission/sequestration by forest types, latitude, and DWM component size. Given the complex dynamics of DWM C flux, early implementation of inventory remeasurement, and relatively low sample size, numerous future research directions are suggested.

  12. Estimation of surface heat flux for ablation and charring of thermal protection material

    Science.gov (United States)

    Qian, Wei-qi; He, Kai-feng; Zhou, Yu

    2016-07-01

    Ablation of the thermal protection material of the reentry hypersonic flight vehicle is a complex physical and chemical process. To estimate the surface heat flux from internal temperature measurement is much more complex than the conventional inverse heat conduction problem case. In the paper, by utilizing a two-layer pyrogeneration-plane ablation model to model the ablation and charring of the material, modifying the finite control volume method to suit for the numerical simulation of the heat conduction equation with variable-geometry, the CGM along with the associated adjoint problem is developed to estimate the surface heat flux. This estimation method is verified with a numerical example at first, the results show that the estimation method is feasible and robust. The larger is the measurement noise, the greater is the deviation of the estimated result from the exact value, and the measurement noise of ablated surface position has a significant and more direct influence on the estimated result of surface heat flux. Furthermore, the estimation method is used to analyze the experimental data of ablation of blunt Carbon-phenolic material Narmco4028 in an arc-heater. It is shown that the estimated surface heat flux agrees with the heating power value of the arc-heater, and the estimation method is basically effective and potential to treat the engineering heat conduction problem with ablation.

  13. Studies of low temperature, low flux radiation embrittlement of nuclear reactor structural materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Odette, G.R.; Lucas, G.E.

    1993-06-01

    There are several existing research programs which have components pertinent to the issue of low flux/low temperature embrittlement; in particular, examination of the Shippingport shield tank which has been exposed to low flux and relatively low temperature is being performed by ANL, and evaluation of low temperature embrittlement in A508 and A533B steels in support of the HTGR is currently being performed by ORNL. However, these programs are not specifically directed at the broader issue of low flux/low temperature embrittlement in a range of structural steels. Hence, the authors coordinated their effort with these programs so that their investigations were complementary to existing programs, and they focused on a set of materials which expand the data base developed in these programs. In particular, the authors have investigated embrittlement phenomena in steels that are similar to those used in support structure.

  14. Self-castellation of tungsten monoblock under high heat flux loading and impact of material properties

    Directory of Open Access Journals (Sweden)

    S. Panayotis

    2017-08-01

    Full Text Available In the full-tungsten divertor qualification program at ITER Organization, macro-cracks, so called self-castellation were found in a fraction of tungsten monoblocks during cyclic high heat flux loading at 20MW/m2. The number of monoblocks with macro-cracks varied with the tungsten products used as armour material. In order to understand correlation between the macro-crack appearance and W properties, an activity to characterize W monoblock materials was launched at the IO. The outcome highlighted that the higher the recrystallization resistance, the lower the number of cracks detected during high heat flux tests. Thermo-mechanical finite element modelling demonstrated that the maximum surface temperature ranges from 1800 °C to 2200 °C and in this range recrystallization of tungsten occurred. Furthermore, it indicated that loss of strength due to recrystallization is responsible for the development of macro-cracks in the tungsten monoblock.

  15. Measured and Predicted Neutron Flux Distributions in a Material Surrounding a Cylindrical Duct

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, J.; Sandlin, R.

    1966-03-15

    The radial fast neutron flux attenuations in the material (iron) surrounding ducts of diameters 7, 9, and 15 cm and total duct length of about 1.5 m have been investigated with and without neutron scattering cans filled with D{sub 2}O in the duct. Experimentally the problem was solved by the use of foil activation techniques. Theoretically it was attacked by, in the first place, a Monte Carlo program specially written for this purpose and utilizing an importance sampling technique. In the second place non- and single-scattering removal flux codes were tried, and also simple hand calculations. The Monte Carlo results accounted well for the fast flux attenuation, while the non- and single-scattering methods overestimated the attenuation generally by a factor of 10 or less. Simple hand calculations using three empirical parameters could be fitted to the measured data within a factor of 1.2 - 1.3 at penetration depths greater than 3 - 4 cm. The distribution of the D{sub 2}O-scattered flux could well be described in terms of single scattering.

  16. Flux of particulate organic material from the euphotic zone of oceans: Estimation from phytoplankton biomass

    Science.gov (United States)

    Legendre, Louis

    1998-02-01

    A major objective of modem biological oceanography is to quantify, model, and predict the downward flux of biogenic carbon. Previous papers have documented an empirical relationship between the sinking flux of particulate organic material from the euphotic zone (S) and phytoplankton biomass (B), in oceans, and suggested that S could be estimated directly from B. The present paper investigates, using a mathematical model and data from the literature, the relationship between S and B. Calculations show that S is determined mostly by B and also by p (instantaneous coefficient of net phytoplankton production minus euphotic zone heterotrophic community respiration and incorporation in the pelagic food web). The regression S = f(B) accounts for 90% of the variation in S. In remote sensing, B is derived from ocean color, phytoplankton production (P) is derived from B, and S is derived from P. Within that context, the biomass approach could be used as an additional means to constrain the estimates of S.

  17. Flux-Grown Piezoelectric Materials: Application to α-Quartz Analogues

    Directory of Open Access Journals (Sweden)

    Pascale Armand

    2014-06-01

    Full Text Available Using the slow-cooling method in selected MoO3-based fluxes, single-crystals of GeO2 and GaPO4 materials with an α-quartz-like structure were grown at high temperatures (T ≥ 950 °C. These piezoelectric materials were obtained in millimeter-size as well-faceted, visually colorless and transparent crystals. Compared to crystals grown by hydrothermal methods, infrared and Raman measurements revealed flux-grown samples without significant hydroxyl group contamination and thermal analyses demonstrated a total reversibility of the α-quartz ↔ β-cristobalite phase transition for GaPO4 and an absence of phase transition before melting for α-GeO2. The elastic constants CIJ (with I, J indices from 1 to 6 of these flux-grown piezoelectric crystals were experimentally determined at room and high temperatures. The ambient results for as-grown α-GaPO4 were in good agreement with those obtained from hydrothermally-grown samples and the two longitudinal elastic constants measured versus temperature up to 850 °C showed a monotonous evolution. The extraction of the ambient piezoelectric stress contribution e11 from the CD11 to CE11 difference gave for the piezoelectric strain coefficient d11 of flux-grown α-GeO2 crystal a value of 5.7(2 pC/N, which is more than twice that of α-quartz. As the α-quartz structure of GeO2 remained stable up to melting, a piezoelectric activity was observed up to 1000 °C.

  18. Estimates of heat flux to material surfaces in Proto-MPEX with IR imaging

    Science.gov (United States)

    Showers, M.; Biewer, T. M.; Bigelow, T. S.; Caughman, J. B. O.; Donovan, D.; Goulding, R. H.; Gray, T. K.; Rapp, J.; Youchison, D. L.; Nygren, R. E.

    2015-11-01

    The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) at Oak Ridge National Laboratory (ORNL) is a linear plasma device with the primary purpose of developing the plasma source concept for the Material Plasma Exposure eXperiment (MPEX), which will address the plasma material interactions (PMI) science for future fusion reactors. New diagnostics for Proto-MPEX include an infrared (IR) camera, in-vessel thermocouples and ex-vessel fluoroptic probes. The IR camera and other diagnostics provide surface temperature measurements of Proto-MPEX's dump and target plates, located on either end of the machine, which are being exposed to plasma. The change in surface temperature is measured over the duration of the plasma shot to determine the heat flux hitting the plates. The IR camera additionally provides 2-D thermal load distribution images of these plates, highlighting Proto-MPEX plasma behaviors, such as hot spots. The plasma diameter on the dump plate is on the order of 15 cm. The combination of measured heat flux and the thermal load distribution gives information on the efficiency of Proto-MPEX as a plasma generating device. Machine operating parameters that will improve Proto-MPEX's performance may be identified, increasing its PMI research capabilities.

  19. Characteristics of a calcite "limestone"-marble from Macedonia, used as flux material

    Directory of Open Access Journals (Sweden)

    Hristova E.

    2003-01-01

    Full Text Available The phase characteristics of calcite "limestone"-marble from Banjany area village (near Skopje, Macedonia were examined by means of XRD, SEM microscope in polarizing and reflected lights, chemical, DT/TG-analyses. It was concluded as follows: - calcite (CaCO3 is a major mineral component (cca 80-90 % prevailing in the marble over the other minerals - dolomite is generally of minor importance (cca 10-20 % in the rock - quartz, micas graphite, pyrite represent typical accessories. As result of the mentioned phase characteristics, this raw materials was for a long time (more than 30 years used as flux in the iron and steel metallurgy in Macedonia.

  20. Plasma under control: Advanced solutions and perspectives for plasma flux management in material treatment and nanosynthesis

    Science.gov (United States)

    Baranov, O.; Bazaka, K.; Kersten, H.; Keidar, M.; Cvelbar, U.; Xu, S.; Levchenko, I.

    2017-12-01

    Given the vast number of strategies used to control the behavior of laboratory and industrially relevant plasmas for material processing and other state-of-the-art applications, a potential user may find themselves overwhelmed with the diversity of physical configurations used to generate and control plasmas. Apparently, a need for clearly defined, physics-based classification of the presently available spectrum of plasma technologies is pressing, and the critically summary of the individual advantages, unique benefits, and challenges against key application criteria is a vital prerequisite for the further progress. To facilitate selection of the technological solutions that provide the best match to the needs of the end user, this work systematically explores plasma setups, focusing on the most significant family of the processes—control of plasma fluxes—which determine the distribution and delivery of mass and energy to the surfaces of materials being processed and synthesized. A novel classification based on the incorporation of substrates into plasma-generating circuitry is also proposed and illustrated by its application to a wide variety of plasma reactors, where the effect of substrate incorporation on the plasma fluxes is emphasized. With the key process and material parameters, such as growth and modification rates, phase transitions, crystallinity, density of lattice defects, and others being linked to plasma and energy fluxes, this review offers direction to physicists, engineers, and materials scientists engaged in the design and development of instrumentation for plasma processing and diagnostics, where the selection of the correct tools is critical for the advancement of emerging and high-performance applications.

  1. Transmutation of plasma facing materials by the neutron flux in a DT fusion reactor

    Energy Technology Data Exchange (ETDEWEB)

    Behrisch, R. [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Khripunov, V.; Santoro, R.T. [The ITER JCT, Max Planck Inst. fuer Plasmaphysik, Garching (Germany); Yesil, J.M

    1998-10-01

    The neutron induced transmutations, gas production, activation, atomic displacements and afterheat have been calculated for several potential low- and high-Z first wall materials in a DT fusion reactor. The neutron spectra taken are those calculated for the first wall of the shielding blanket proposed for the international thermonuclear experimental reactor (ITER). For low Z materials the production of hydrogen and helium isotopes dominate, while for high Z materials activation and afterheat dominate. For a total flux of 14.1 MeV neutrons corresponding to a wall load of 1 MW a m{sup -2}, the tritium production in a 1 cm thick low Z material layer of the first wall is of the order of 10{sup 16} - 10{sup 19} cm{sup -2}, while the calculated He concentrations are of the order of {proportional_to}10{sup -3} per wall atom or 10{sup 20} cm{sup -2}. These gases may modify the thermophysical properties of the wall material. (orig.) 34 refs.

  2. Confirmatory investigations on the flux effect and associated unstable matrix damage in RPV materials exposed to high neutron fluence

    Energy Technology Data Exchange (ETDEWEB)

    Chaouadi, R., E-mail: rachid.chaouadi@sckcen.be [SCK-CEN, Boeretang 200, 2400 Mol (Belgium); Gérard, R. [Tractebel Engineering, Avenue Ariane 7, 1200 Brussels (Belgium)

    2013-06-15

    This paper provides additional experimental data on the neutron flux effect on RPV hardening and embrittlement and on the so-called unstable matrix damage that was suggested to occur at high flux. Six materials taken from the first irradiation surveillance capsules of Belgian PWRs with a fluence not exceeding about 1.5 × 10{sup 19} n/cm{sup 2} were further irradiated in the BR2 high flux reactor to additional fluences ranging between about 1 and 1.5 × 10{sup 20} n/cm{sup 2} at 290 °C. Eight additional RPV materials were selected to investigate the flux effect on irradiation hardening. No statistically-significant difference in irradiation hardening for low and high flux could be evidenced from the null hypothesis test applied with the general linear model. This is confirmed by additional experiments where fourteen irradiated specimens of various RPV materials consisting of low to high Cu and Ni contents were annealed at 350 °C for 5 h to eventually reveal some recovery of the unstable matrix damage. The results did not show any recovery upon heat treatment, which indicates that unstable matrix defects did not appear in these materials during irradiation at high flux.

  3. A study of influence of material properties on magnetic flux density induced in magneto rheological damper through finite element analysis

    Directory of Open Access Journals (Sweden)

    Gurubasavaraju T. M.

    2018-01-01

    Full Text Available Magnetorheological fluids are smart materials, which are responsive to the external stimulus and changes their rheological properties. The damper performance (damping force is dependent on the magnetic flux density induced at the annular gap. Magnetic flux density developed at fluid flow gap of MR damper due to external applied current is also dependent on materials properties of components of MR damper (such as piston head, outer cylinder and piston rod. The present paper discus about the influence of different materials selected for components of the MR damper on magnetic effect using magnetostatic analysis. Different materials such as magnetic and low carbon steels are considered for piston head of the MR damper and magnetic flux density induced at fluid flow gap (filled with MR fluid is computed for different DC current applied to the electromagnetic coil. Developed magnetic flux is used for calculating the damper force using analytical method for each case. The low carbon steel has higher magnetic permeability hence maximum magnetic flux could pass through the piston head, which leads to higher value of magnetic effect induction at the annular gap. From the analysis results it is observed that the magnetic steel and low carbon steel piston head provided maximum magnetic flux density. Eventually the higher damping force can be observed for same case.

  4. Calculation and comparisons with measurement of fast neutron fluxes in the material testing facilities of the NRU research reactor

    Energy Technology Data Exchange (ETDEWEB)

    Leung, T.C. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2012-07-01

    The NRU reactor at Chalk River provides three irradiation facilities to study the effects of fast neutrons (E> 1 MeV) on reactor materials for assessing material damage and deformation. The facilities comprise two types of fast neutron rods (Mark 4 and Mark 7), and a Material Test Bundle (MTB) irradiated in a loop site. This paper describes the neutronic simulation of these testing facilities using the WIMS-AECL and TRIAD codes, and comparisons with the fast neutron flux measurements using iron-wire activation techniques. It also provides comparisons of flux levels, neutron spectra, and size limitations of the experimental cavities between these test facilities. (author)

  5. Phase Change Materials-Assisted Heat Flux Reduction: Experiment and Numerical Analysis

    Directory of Open Access Journals (Sweden)

    Hussein J. Akeiber

    2016-01-01

    Full Text Available Phase change materials (PCM in the construction industry became attractive because of several interesting attributes, such as thermo-physical parameters, open air atmospheric condition usage, cost and the duty structure requirement. Thermal performance optimization of PCMs in terms of proficient storage of a large amount of heat or cold in a finite volume remains a challenging task. Implementation of PCMs in buildings to achieve thermal comfort for a specific climatic condition in Iraq is our main focus. From this standpoint, the present paper reports the experimental and numerical results on the lowering of heat flux inside a residential building using PCM, which is composed of oil (40% and wax (60%. This PCM (paraffin, being plentiful and cost-effective, is extracted locally from waste petroleum products in Iraq. Experiments are performed with two rooms of identical internal dimensions in the presence and absence of PCM. A two-dimensional numerical transient heat transfer model is developed and solved using the finite difference method. A relatively simple geometry is chosen to initially verify the numerical solution procedure by incorporating in the computer program two-dimensional elliptic flows. It is demonstrated that the heat flux inside the room containing PCM is remarkably lower than the one devoid of PCM.

  6. Investigating the suitability of GaAs:Cr material for high flux X-ray imaging

    Science.gov (United States)

    Veale, M. C.; Bell, S. J.; Duarte, D. D.; French, M. J.; Hart, M.; Schneider, A.; Seller, P.; Wilson, M. D.; Kachkanov, V.; Lozinskaya, A. D.; Novikov, V. A.; Tolbanov, O. P.; Tyazhev, A.; Zarubin, A. N.

    2014-12-01

    Semi-insulating wafers of GaAs material with a thickness of 500μm have been compensated with chromium by Tomsk State University. Initial measurements have shown the material to have high resistivity (3 × 109Ωcm) and tests with pixel detectors on a 250 μm pitch produced uniform spectroscopic performance across an 80 × 80 pixel array. At present, there is a lack of detectors that are capable of operating at high X-ray fluxes (> 108 photons s-1 mm-2) in the energy range 5-50 keV. Under these conditions, the poor stopping power of silicon, as well as issues with radiation hardness, severely degrade the performance of traditional detectors. While high-Z materials such as CdTe and CdZnTe may have much greater stopping power, the formation of space charge within these detectors degrades detector performance. Initial measurements made with GaAs:Cr detectors suggest that many of its material properties make it suitable for these challenging conditions. In this paper the radiation hardness of the GaAs:Cr material has been measured on the B16 beam line at the Diamond Light Source synchrotron. Small pixel detectors were bonded to the STFC Hexitec ASIC and were irradiated with 3 × 108 photons s-1 mm-2 monochromatic 12 keV X-rays up to a maximum dose of 0.6 MGy. Measurements of the spectroscopic performance before and after irradiation have been used to assess the extent of the radiation damage.

  7. Fluxes of material in the Arabian Sea and Bay of Bengal - Sediment trap studies

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.; Nair, R.R.

    In order to investigate how monsoons influence biogeochemical fluxes in the ocean, twelve time-series sediment traps were deployed at six locations in the northern Indian Ocean. In this paper we present particle flux data collected during May 1986...

  8. Irradiation of structural materials in contact with lead bismuth eutectic in the high flux reactor

    Energy Technology Data Exchange (ETDEWEB)

    Magielsen, A.J., E-mail: magielsen@nrg.eu [Nuclear Research and Consultancy Group, Westerduinweg 3, Postbus 25, 1755 ZG Petten (Netherlands); Jong, M.; Bakker, T.; Luzginova, N.V.; Mutnuru, R.K.; Ketema, D.J.; Fedorov, A.V. [Nuclear Research and Consultancy Group, Westerduinweg 3, Postbus 25, 1755 ZG Petten (Netherlands)

    2011-08-31

    In the framework of the materials domain DEMETRA in the European Transmutation research and development project EUROTRANS, irradiation experiment IBIS has been performed in the High Flux Reactor in Petten. The objective was to investigate the synergystic effects of irradiation and lead bismuth eutectic exposure on the mechanical properties of structural materials and welds. In this experiment ferritic martensitic 9 Cr steel, austenitic 316L stainless steel and their welds have been irradiated for 250 Full Power Days up to a dose level of 2 dpa. Irradiation temperatures have been kept constant at 300 deg. C and 500 deg. C. During the post-irradiation test phase, tensile tests performed on the specimens irradiated at 300 deg. C have shown that the irradiation hardening of ferritic martensitic 9 Cr steel at 1.3 dpa is 254 MPa, which is in line with the irradiation hardening obtained for ferritic martensitic Eurofer97 steel investigated in the fusion program. This result indicates that no LBE interaction at this irradiation temperature is present. A visual inspection is performed on the specimens irradiated in contact with LBE at 500 deg. C and have shown blackening on the surface of the specimens and remains of LBE that makes a special cleaning procedure necessary before post-irradiation mechanical testing.

  9. The downward flux of biogenic material in the NE subarctic Pacific: importance of algal sinking and mesozooplankton herbivory

    Science.gov (United States)

    Thibault, D.; Roy, S.; Wong, C. S.; Bishop, J. K.

    1999-11-01

    In the present study we examine factors that affect the downward flux of biogenic carbon in the NE subarctic Pacific, one of the important high-nutrient-low-chlorophyll (HNLC) regions in the open ocean. We focus on the role of mesozooplankton, since their seasonal peaks in biomass and growth are in phase with the seasonal variations in the downward POC fluxes, whereas phytoplankton biomass is more-or-less uniform year-round. The relative importance of mesozooplankton and algal sinking was examined using the pigment composition of material accumulated in short-term free-drifting sediment traps positioned just below the upper stratified surface layer (ca. 100-200 m). This was compared with the phytoplankton composition in the surface waters, and with the grazing activity (gut pigments and fecal pellet production rates) of the most abundant large copepods. We also examined whether the relationships between the downward flux of carbon and pelagic processes were similar in the coastal, continental margin and offshore HNLC regions of the NE subarctic Pacific, the latter represented by Ocean Station Papa (OSP). Our results show that grazing had a variable impact on the downward flux of biogenic carbon. Carbon-transformed pheopigments (particularly pyropheophorbide a, frequently associated with copepod grazing) represented up to 13% of the total downward POC flux inshore (in May 1996) and 8-9% at OSP in May and February 1996, respectively. This flux of pheopigments was accompanied by a large potential input of fecal pellets from large copepods (as estimated from defecation rates of freshly collected animals) only in May 1996 at OSP, suggesting that pheopigments came from other sources (other herbivores, senescing algae) in February. The larger flux of pheopigments in May was probably related to the abundance of mesozooplankton at that time of the year. During summer (August 1996), both the flux of pheopigments and the potential input of fecal pellets from large copepods

  10. Social interactions among grazing reef fish drive material flux in a coral reef ecosystem.

    Science.gov (United States)

    Gil, Michael A; Hein, Andrew M

    2017-05-02

    In human financial and social systems, exchanges of information among individuals cause speculative bubbles, behavioral cascades, and other correlated actions that profoundly influence system-level function. Exchanges of information are also widespread in ecological systems, but their effects on ecosystem-level processes are largely unknown. Herbivory is a critical ecological process in coral reefs, where diverse assemblages of fish maintain reef health by controlling the abundance of algae. Here, we show that social interactions have a major effect on fish grazing rates in a reef ecosystem. We combined a system for observing and manipulating large foraging areas in a coral reef with a class of dynamical decision-making models to reveal that reef fish use information about the density and actions of nearby fish to decide when to feed on algae and when to flee foraging areas. This "behavioral coupling" causes bursts of feeding activity that account for up to 68% of the fish community's consumption of algae. Moreover, correlations in fish behavior induce a feedback, whereby each fish spends less time feeding when fewer fish are present, suggesting that reducing fish stocks may not only reduce total algal consumption but could decrease the amount of algae each remaining fish consumes. Our results demonstrate that social interactions among consumers can have a dominant effect on the flux of energy and materials through ecosystems, and our methodology paves the way for rigorous in situ measurements of the behavioral rules that underlie ecological rates in other natural systems.

  11. Vertical fluxes of particulate biogenic material through the euphotic and twilight zones in the Cariaco Basin, Venezuela

    Science.gov (United States)

    Montes, Enrique; Muller-Karger, Frank; Thunell, Robert; Hollander, David; Astor, Yrene; Varela, Ramón; Soto, Inia; Lorenzoni, Laura

    2012-09-01

    Surface-tethered particle interceptor traps (PITs) were deployed at 50 and 100 m (1-3 days) on ten occasions in the Cariaco Basin between March 2007 and November 2009 to measure the settling fluxes of biogenic particles at 50 m (the base of the euphotic zone—Ez) and 100 m. Fluxes at these two depths were compared to concurrent fluxes estimated with moored sediment traps at 150, 225 and 410 m from the CARIACO Ocean Time-Series program. We measured particulate organic carbon (POC), particulate organic nitrogen (PON), calcium carbonate, biogenic silica and terrigenous material concentrations in samples collected with both the drifting and moored traps. We also estimated the fluxes of foraminifera shells and coccolithophore cells at 50 and 100 m using drifting traps samples. Surface chlorophyll a and primary production observations during each sampling period were examined to quantify the relationship between the magnitude and geochemical composition of the vertical flux and overlying production. Surface chlorophyll a concentrations and primary production rates were highest during months of upwelling (2.58-1.35 mg m-3 and 3.6-1.4 g C m-2 d-1, respectively). The fluxes of POC, PON, calcite and silica measured during the upwelling season (December-May) were typically higher than during the period of non-upwelling (August-November), when surface waters are more strongly stratified. POC fluxes measured with the drifting traps (50 and 100 m) varied between 0.95 (upwelling) and 0.14 g m-2 d-1 (non-upwelling), compared with those from the moored traps (150, 225 and 410 m) which ranged from 0.21 to 0.01 g m-2 d-1. Similarly, the fluxes of biogenic opal in the upper 100 m ranged from 1.12 and 0.18 g m-2 d-1, and those at greater depths varied from 0.27 g m-2 d-1 during upwelling to values near zero during stratification periods. The fluxes of POC, PON, calcite and silica in the upper 100 m decreased by an order of magnitude at the depth of the oxic-anoxic interface (>200 m

  12. On the reliable determination of the magnetic field for first flux-line penetration in technical niobium material

    Energy Technology Data Exchange (ETDEWEB)

    Ganapati Rao Myneni

    2007-09-05

    We present a way to reliably determine the field for first penetration H$_P$ in various kinds of bulk samples of niobium material used in the technical applications like fabrication of superconducting RF-cavities. Special attention is given to the role of flux line pinning in the determination of H$_P$. It is observed that the pinning properties and H$_P$ can change (or can be altered) significantly with the chemical treatment of bulk niobium. A correlation is proposed between H$_P$ of the niobium materials and the anomalous high-field Q-drop observed in the superconducting RF-cavities fabricated using such niobium material.

  13. Investigations of water bounded in clam mussels (Mytilius edulis) by nuclear magnetic relaxation for protons; Badanie wody zwiazanej w muszlach omulka (Mytillus edulls) metoda magnetycznej relaksacji dla protonow

    Energy Technology Data Exchange (ETDEWEB)

    Haranczyk, H.; Niziol, J. [Inst. Fizyki, Uniwersytet Jagiellonski, Cracow (Poland); Falniowski, A. [Inst. Zoologii, Uniwersytet Jagiellonski, Cracow (Poland)

    1994-12-31

    The process of water bounding in clam shells has been investigated by nuclear magnetic relaxation of protons measurements. Decomposition of measured relaxation functions have been done using the specially constructed computer program. 4 refs, 4 figs, 3 tabs.

  14. Remote Heat Flux Using a Self Calibration Multiwavelength Pyrometer and a Transparent Material

    Science.gov (United States)

    Ng, Daniel

    1998-01-01

    A self calibrating multiwavelength pyrometer was used to conduct remote heat flux measurements using a transparent sapphire disk by determining the sapphire disk's front and back surface temperatures. Front surface temperature (Tfs) was obtained from detection of surface emitted radiation at long wavelengths (k = 6 gm). Back surface temperature (Tbs) was obtained from short wavelength (1 to 5 gm) radiation transmitted through the sapphire disk. The thermal conductivity of the sapphire disk and the heat transfer coefficients h, and h2 of its surfaces are determined experimentally. An analysis of the heat flux measurement is presented.

  15. Remote Heat Flux Measurement Using a Self Calibration Multiwavelength Pyrometer and a Transparent Material

    Science.gov (United States)

    Ng, Daniel

    1998-01-01

    A self calibrating multiwavelength pyrometer was used to conduct remote heat flux measurements using a transparent sapphire disk by determining the sapphire disk's front and back surface temperatures. Front surface temperature (Tfs) was obtained from detection of surface emitted radiation at long wavelengths (lambda > 6 micrometers). Back surface temperature (Tbs) was obtained from short wavelength (1 to 5 micrometers) radiation transmitted through the sapphire disk. The thermal conductivity k of the sapphire disk and the heat transfer coefficients h(sub 1) and h(sub 2) of its surfaces are determined experimentally. An analysis of the heat flux measurement is presented.

  16. Smoke Emissions from Aircraft Interior Materials at Elevated Heat Flux Levels Using Modified NBS Smoke Chamber.

    Science.gov (United States)

    1979-07-01

    sample actually grew out of the holder and extended toward the furnace, pro- ducing a dense, black , sooty smoke at the higher heat fluxes. It then...also pro- ducing vast amounts of black , sooty smoke at the higher heat fluxes. For these two plastics, smoke increased monotonically with increasing...PVF/f iberglaes-phenolic/ 0.505 89.9 Pmel Overhead Nomex Peper -phenolic Stowage honeycomb/fiberglass phenolic .26 Wool Car,e 0.250 74.0 Floering

  17. Modeling Water Flux at the Base of the Rooting Zone for Soils with Varying Glacial Parent Materials

    Science.gov (United States)

    Naylor, S.; Ellett, K. M.; Ficklin, D. L.; Olyphant, G. A.

    2013-12-01

    Soils of varying glacial parent materials in the Great Lakes Region (USA) are characterized by thin unsaturated zones and widespread use of agricultural pesticides and nutrients that affect shallow groundwater. To better our understanding of the fate and transport of contaminants, improved models of water fluxes through the vadose zones of various hydrogeologic settings are warranted. Furthermore, calibrated unsaturated zone models can be coupled with watershed models, providing a means for predicting the impact of varying climate scenarios on agriculture in the region. To address these issues, a network of monitoring sites was developed in Indiana that provides continuous measurements of precipitation, potential evapotranspiration (PET), soil volumetric water content (VWC), and soil matric potential to parameterize and calibrate models. Flux at the base of the root zone is simulated using two models of varying complexity: 1) the HYDRUS model, which numerically solves the Richards equation, and 2) the soil-water-balance (SWB) model, which assumes vertical flow under a unit gradient with infiltration and evapotranspiration treated as separate, sequential processes. Soil hydraulic parameters are determined based on laboratory data, a pedo-transfer function (ROSETTA), field measurements (Guelph permeameter), and parameter optimization. Groundwater elevation data are available at three of six sites to establish the base of the unsaturated zone model domain. Initial modeling focused on the groundwater recharge season (Nov-Feb) when PET is limited and much of the annual vertical flux occurs. HYDRUS results indicate that base of root zone fluxes at a site underlain by glacial ice-contact parent materials are 48% of recharge season precipitation (VWC RMSE=8.2%), while SWB results indicate that fluxes are 43% (VWC RMSE=3.7%). Due in part to variations in surface boundary conditions, more variable fluxes were obtained for a site underlain by alluvium with the SWB model (68

  18. Studies of low temperature, low flux radiation embrittlement of nuclear reactor structural materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Odette, G.R.; Lucas, G.E.

    1998-09-02

    A large matrix of simple alloys and complex commercial type steels was irradiated over a range of fluxes at 60 C up to a fast fluence of about 3 {times} 10{sup 22} n/m{sup 2}. Combined with data in the literature, these results show a negligible effect of flux on irradiation hardening in the range of 2 {times} 10{sup 13} to 5 {times} 10{sup 18} n/m{sup 2}-s. This observation lends indirect support to the proposal that the accelerated embrittlement in the High Flux Isotope Reactor surveillance steels was due to an anomalously high level of damage from gamma rays. A weak dependence of hardening on a number of elements, including copper, nickel, phosphorus, molybdenum and manganese, can be described by a simple empirical chemistry factor. Particular combinations of elements resulted in hardening differences of up to about 60% in the complex commercial type steels and up to about 100% in simple model alloys. Direct effects of microstructure appear to be minimal. Hardening varies with the square root of fluence above a threshold around 4 {times} 10{sup 20} n/m{sup 2}. The results suggest that low temperature hardening is dominated by local intracascade processes leading to the formation of small defect-solute clusters/complexes. The observed hardening corresponds to nominal maximum end-of-life transition temperature shifts in support structure steels of about 120 C.

  19. Heat conduction in nanoscale materials: a statistical-mechanics derivation of the local heat flux.

    Science.gov (United States)

    Li, Xiantao

    2014-09-01

    We derive a coarse-grained model for heat conduction in nanoscale mechanical systems. Starting with an all-atom description, this approach yields a reduced model, in the form of conservation laws of momentum and energy. The model closure is accomplished by introducing a quasilocal thermodynamic equilibrium, followed by a linear response approximation. Of particular interest is the constitutive relation for the heat flux, which is expressed nonlocally in terms of the spatial and temporal variation of the temperature. Nanowires made of copper and silicon are presented as examples.

  20. A Petawatt-Laser-Driven, High-Flux Neutron Source for Fusion Micro-Materials Irradiation

    Science.gov (United States)

    Logan, B. G.; Perkins, L. J.; Ditmire, T.; Rosen, M. D.; Perry, M. D.; Key, M. H.; Diaz de La Rubia, T.; Wolfer, W. G.

    1998-11-01

    We are examining the application of petawatt lasers to create beam-target fusion neutrons via ponderomotive-driven, electrostatic coupling. This offers a low cost, high-flux, “micro” 14MeV neutron source for testing tensile strengths of small ( ~100μm) fibers of C, Al_2O_3, SiC, etc., to ~100dpa. Such fibers can form porous fabric tubes for flowing coolant/breeders ( Flibe, LiPb, LiO_2-sand) in a various applications (direct-drive ICF, spheromaks, etc.). Under very short, intense laser heating of a thin tritium-frost layer, ejection of hot (multi-MeV) tail electrons driven by the ponderomotive pressure of the laser field competes with thermal electron heat conduction. Hot ions are ejected from the tritium layer by the resulting potential and move into a deuterium-ice substrate, pre-heated by the hot electrons. Beam-target fusion neutrons are produced at high efficiency (i.e., Q ~0.01-0.1 relative to Q ~0.001 for conventional solid, cold targets), while small target dimensions yield high neutron fluxes. Formal treatment of laser-induced electrostatic potentials is required to accurately model electron/ion transport.

  1. Development of a low-cost double rotor axial flux motor with soft magnetic composite and ferrite permanent magnet materials

    Science.gov (United States)

    Liu, Chengcheng; Zhu, Jianguo; Wang, Youhua; Guo, Youguang; Lei, Gang; Liu, Xiaojing

    2015-05-01

    This paper proposes a low-cost double rotor axial flux motor (DRAFM) with low cost soft magnetic composite (SMC) core and ferrite permanent magnets (PMs). The topology and operating principle of DRAFM and design considerations for best use of magnetic materials are presented. A 905 W 4800 rpm DRAFM is designed for replacing the high cost NdFeB permanent magnet synchronous motor (PMSM) in a refrigerator compressor. By using the finite element method, the electromagnetic parameters and performance of the DRAFM operated under the field oriented control scheme are calculated. Through the analysis, it is shown that that the SMC and ferrite PM materials can be good candidates for low-cost electric motor applications.

  2. The Thermoelectric Analysis of Different Heat Flux Conduction Materials for Power Generation Board

    Directory of Open Access Journals (Sweden)

    Siyang Li

    2017-11-01

    Full Text Available The development of the thermoelectric (TE power generation is rapid, and the applications have extensively been studied. The principle is based on the Seebeck effect, in which the temperature difference between hot and cold sides of the TE material converts to electrical energy. In this paper, a design is proposed to convert the thermal energy between indoor and outdoor of a board to electrical energy by the thermoelectric generator (TEG. Furthermore, the electrical energy generated is charged to supercapacitors as a battery or a power supply to the loads (e.g., lights of the house. Besides the experimental work, a thermal model and an electrical model of the TEG have been proposed. To study the power generation performance in terms of materials, the simulation of the conversion efficiency of the TE board using materials with different thermal conductance have also been conducted. It was found that, using graphene as the thermally conductive material, the conversion efficiency was enhanced by 1.6% and 1.7%, when the temperature difference was 15 °C and 40 °C, respectively.

  3. Use of sugarcane bagasse ashes as raw material in the replacement of fluxes for applications on porcelain tile

    Energy Technology Data Exchange (ETDEWEB)

    Paranhos, R.J.S.; Silva, V.M. da; Acchar, W. [Instituto Federal de Educacao, Ciencia e Tecnologia da Bahia (IFBA), BA (Brazil)

    2016-07-01

    Full text: This study evaluated the potential use of Sugarcane Bagasse Ashes (SBA) as a flux, replacing phyllite for the production of enamelled porcelain tile. The raw materials of the standard mass components and the SBA residue were characterized by testing by XRF, XRD, AG, DTA and TGA. Test samples were fabricated, assembled in lots of 3 units and sintered at temperatures of 1150 ° C to 1210 ° C. The results of the physical properties, mechanical properties and SEM of the sintered samples, showed that the formulation, G4 - in which applied 10% of SBA replacing phyllite, sintering temperature 1210 ° C showed better performance as the previously mentioned properties due to the formation of mullite crystals, meeting the prerequisites of standards for enamelled porcelain tile, while reducing the environmental impact and the cost of production. (author)

  4. Simulation of Field Dependence of Critical Current Densities of Bulk High Tc Superconducting Materials regarding Thermally Activated Flux Motion

    Science.gov (United States)

    Santosh, M.; Naik, S. Pavan Kumar; Koblischka, M. R.

    2017-07-01

    In the upcoming generation, bulk high temperature superconductors (HTS) will play a crucial and a promising role in numerous industrial applications ranging from Maglev trains to magnetic resonance imaging, etc. Especially, the bulk HTS as permanent magnets are suitable due to the fact that they can trap magnetic fields being several orders of magnitude higher than those of the best hard ferromagnets. The bulk HTS LREBa2Cu3O7-δ (LREBCO or LRE-123, LRE: Y, Gd, etc.,) materials could obtain very powerful compact superconducting super-magnets, which can be operated at the cheaper liquid nitrogen temperature or below due to higher critical temperatures (i.e., ∼90 K). As a result, the new advanced technology can be utilized in a more attractive manner for a variety of technological and medical applications which have the capacity to revolutionize the field. An understanding of the magnetic field dependence of the critical current density (J c(H)) is important to develop better adapted materials. To achieve this goal, a variety of Jc (H) behaviours of bulk LREBCO samples were modelled regarding thermally activated flux motion. In essence, the Jc (H) curves follows a certain criterion where an exponential model is applied. However, to fit the complete Jc (H) curve of the LRE-123 samples an unique model is necessary to explain the behavior at low and high fields. The modelling of the various superconducting materials could be understood in terms of the pinning mechanisms.

  5. Effect of high-flux, low-energy He+ ion irradiation on Ta as a plasma-facing material

    Science.gov (United States)

    Novakowski, T. J.; Tripathi, J. K.; Hassanein, A.

    2016-12-01

    The goal of this work is to assess Ta as a potential plasma-facing material for future fusion reactors in terms of its response to high-flux, low-energy He+ ion irradiation. Ta samples were irradiated with 100 eV He+ ions at various fluences up to 3.5 × 1025 ions m-2 while simultaneously heated at constant temperatures in the range 823-1223 K. SEM studies show that irradiated Ta surfaces undergo significant morphology changes that have a strong dependence on both ion fluence and sample temperature. Optical reflectivity complements SEM and demonstrates a vertical growth of surface structures with increasing fluence. Ex situ XPS and XRD both show significant oxidation of the irradiated Ta surfaces, giving further qualitative information on the extent of surface modification. Overall, these irradiation-induced structures on Ta are similar to early-stage “fuzz” structures observed in W. However, Ta exhibits a higher fluence threshold for structure formation. While Ta may have less desirable bulk properties (e.g., thermal conductivity) when compared to W, its higher resilience to He+ ion-induced surface modification suggests that surface thermal and mechanical properties may not degrade as quickly in extreme fusion environments; this quality may be a redeeming factor for Ta as a plasma-facing material.

  6. Herbivore-mediated material fluxes in a northern deciduous forest under elevated carbon dioxide and ozone concentrations.

    Science.gov (United States)

    Meehan, Timothy D; Couture, John J; Bennett, Alison E; Lindroth, Richard L

    2014-10-01

    Anthropogenic changes in atmospheric carbon dioxide (CO2 ) and ozone (O3 ) are known to alter tree physiology and growth, but the cascading effects on herbivore communities and herbivore-mediated nutrient cycling are poorly understood. We sampled herbivore frass, herbivore-mediated greenfall, and leaf-litter deposition in temperate forest stands under elevated CO2 (c. 560 ppm) and O3 (c. 1.5× ambient), analyzed substrate chemical composition, and compared the quality and quantity of fluxes under multiple atmospheric treatments. Leaf-chewing herbivores fluxed 6.2 g m(-2)  yr(-1) of frass and greenfall from the canopy to the forest floor, with a carbon : nitrogen (C : N) ratio 32% lower than that of leaf litter. Herbivore fluxes of dry matter, C, condensed tannins, and N increased under elevated CO2 (35, 32, 63 and 39%, respectively), while fluxes of N decreased (18%) under elevated O3 . Herbivore-mediated dry matter inputs scaled across atmospheric treatments as a constant proportion of leaf-litter inputs. Increased fluxes under elevated CO2 were consistent with increased herbivore consumption and abundance, and with increased plant growth and soil respiration, previously reported for this experimental site. Results suggest that insect herbivory will reinforce other factors, such as photosynthetic rate and fine-root production, impacting C sequestration by forests in future environments. © 2014 The Authors New Phytologist © 2014 New Phytologist Trust.

  7. Magnetic flux distribution in a ferromagnetic material magnetized by U-shaped electromagnets of different geometric dimensions types

    Directory of Open Access Journals (Sweden)

    Povolotskaya Anna

    2018-01-01

    Full Text Available A model experiment has been carried out on studying the type of changes in the magnetic induction in a homogeneous isotropic sample that is locally magnetized with attached U-type electromagnets of different geometrical dimensions. The study was aimed at finding out magnetic flux distribution at different locations within the sample and determining the effect that the geometry of attached electromagnets has on this distribution.

  8. Behavior of divertor and first wall armour materials at plasma heat fluxes relevant to ITER ELMs and disruptions

    Directory of Open Access Journals (Sweden)

    D.V. Kovalenko

    2017-08-01

    Full Text Available The paper presents the main results of numerous experiments carried out over the past 10 years at QSPA-T and QSPA-Be plasma guns in support of ITER. Special targets made of pure W, W-1%La2O3 and two types of Be (TGP-56FW and S65-C were tested under the series of repeated plasma stream and photonic flux impact. Maximum heat load on the target surface was up to 2.5MJ/m2 in the case of plasma testing and was equal to 0.5MJ/m2 in the case of photonic flux testing. Pulse waveform was rectangular with tpulse= 0.5ms. It was found that the main erosion mechanisms of W and Be under plasma stream impact are the melt layer movement, the ejection of droplets and the cracks formation. As a result of repeated photonic fluxes a regular, “corrugated” structure are eventually formed on the Be target surface. Study of erosion products of W formed under plasma stream impact on the W target has shown that the D/W atomic ratio in the deposited W films during pulsed events may be the same or even higher than that for stationary processes.

  9. Selection of support structure materials for irradiation experiments in the HFIR (High Flux Isotope Reactor) at temperatures up to 500 degrees C

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, K.; Longest, A.W.

    1990-01-01

    The key factor in the design of capsules for irradiation of test specimens in the High Flux Isotope Reactor at preselected temperatures up to 500{degree}C utilizing nuclear heating is a narrow gas-filled gap which surrounds the specimens and controls the transfer of heat from the specimens through the wall of a containment tube to the reactor cooling water. Maintenance of this gap to close tolerances is dependent on the characteristics of the materials used to support the specimens and isolate them from the water. These support structure materials must have low nuclear heating rates, high thermal conductivities, and good dimensional stabilities under irradiation. These conditions are satisfied by certain aluminum alloys. One of these alloys, a powder metallurgy product containing a fine dispersion of aluminum oxide, is no longer manufactured. A new alloys of this type, with the trade name DISPAL, is determined to be a suitable substitute. 23 refs., 13 figs., 3 tabs.

  10. Force sensor using changes in magnetic flux

    Science.gov (United States)

    Pickens, Herman L. (Inventor); Richard, James A. (Inventor)

    2012-01-01

    A force sensor includes a magnetostrictive material and a magnetic field generator positioned in proximity thereto. A magnetic field is induced in and surrounding the magnetostrictive material such that lines of magnetic flux pass through the magnetostrictive material. A sensor positioned in the vicinity of the magnetostrictive material measures changes in one of flux angle and flux density when the magnetostrictive material experiences an applied force that is aligned with the lines of magnetic flux.

  11. Impact analysis of the decline of agricultural land-use on flood risk and material flux in hilly and mountainous watersheds

    Directory of Open Access Journals (Sweden)

    Y. Shimizu

    2015-06-01

    Full Text Available Agricultural land-use has been reduced by mainly urbanization and devastation in Japan. The objective of this study is to evaluate the impact of the decline of agricultural land-use on flood risk and material flux in hilly and mountainous watersheds using Soil Water Assessment Tool. The results indicated that increase of flood risk due to abandonment of agricultural land-use. Furthermore, the abandonment of rice paddy field on steep slope areas may have larger impacts on sediment discharges than cultivated field. Therefore, it is suggested that prevention of expansion of abandonment of rice paddy field is an important factor in the decrease of yields of sediment and nutrients.

  12. Influence of Different Moderator Materials on Characteristics of Neutron Fluxes Generated under Irradiation of Lead Target with Proton Beams

    CERN Document Server

    Sosnin, A N; Polanski, A; Petrochenkov, S A; Golovatyuk, V M; Krivopustov, M I; Bamblevski, V P; Westmeier, W; Odoj, R; Brandt, R; Robotham, H; Hashemi-Nezhad, S R; Zamani-Valassiadou, M

    2002-01-01

    Neutron fields generated in extended heavy (Z\\geq 82) targets under irradiation with proton beams at energies in the range of 1 GeV are investigated. Influence of different moderators on the spectra and multiplicities of neutrons escaping the surface of the assembly consisting of a lead target (\\varnothing 8 cm\\times 20 cm or \\varnothing 8cm\\times 50 cm) screened by variable thickness of polyethylene or graphite, respectively, was compared in the present work. It is shown that the effectiveness of graphite as a material used in such assemblies to moderate spallation neutrons down to thermal energies is significantly lower than that of paraffin.

  13. ) Mold Fluxes

    Science.gov (United States)

    Seo, Myung-Duk; Shi, Cheng-Bin; Cho, Jung-Wook; Kim, Seon-Hyo

    2014-10-01

    The effects of basicity (CaO/SiO2), B2O3, and Li2O addition on the crystallization behaviors of lime-silica-based mold fluxes have been investigated by non-isothermal differential scanning calorimetry (DSC), field emission scanning electron microscopy, X-ray diffraction (XRD), and single hot thermocouple technique. It was found that the crystallization temperature of cuspidine increased with increasing the basicity of mold fluxes. The crystallization of wollastonite was suppressed with increasing the mold flux basicity due to the enhancement of cuspidine crystallization. The addition of B2O3 suppresses the crystallization of mold flux. The crystallization temperature of mold flux decreases with Li2O addition. The size of cuspidine increases, while the number of cuspidine decreases with increasing mold flux basicity. The morphology of cuspidine in mold fluxes with lower basicity is largely dendritic. The dendritic cuspidine in mold fluxes is composed of many fine cuspidine crystals. On the contrary, in mold fluxes with higher basicity, the cuspidine crystals are larger in size with mainly faceted morphology. The crystalline phase evolution was also calculated using a thermodynamic database, and compared with the experimental results determined by DSC and XRD. The results of thermodynamic calculation of crystalline phase formation are in accordance with the results determined by DSC and XRD.

  14. Damage behavior of REE-doped W-based material exposed to high-flux transient heat loads

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Jing [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Luo, Lai–Ma, E-mail: luolaima@126.com [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province, Hefei 230009 (China); Lin, Jin–shan [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zan, Xiang; Zhu, Xiao–yong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province, Hefei 230009 (China); Xu, Qiu [Research Reactor Institute, Kyoto University, Osaka-Fu 590-0494 (Japan); Wu, Yu–Cheng, E-mail: ycwu@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province, Hefei 230009 (China)

    2016-12-15

    Pure W and W-Lu alloys were prepared by mechanical alloying (MA) and spark plasma sintering (SPS) technology. The performance and relevant damage mechanism of W-(0%, 2%, 5%, 10%) Lu alloys under transient heat loads were investigated using a laser beam heat load test to simulate the transient events in future nuclear fusion reactors. Scanning electron microscopy was used to observe the morphologies of the damaged surfaces and energy dispersive X-ray spectroscopy was used to conduct composition analysis. Damages to the surface such as cracks, pits, melting layers, Lu-rich droplets, and thermal ablation were observed. A mass of dense fuzz-like nanoparticles formed on the outer region of the laser-exposed area. Recrystallization, grain growth, increased surface roughness, and material erosion were also observed. W-Lu samples with low Lu content demonstrated better thermal performance than pure W, and the degree of damage significantly deteriorated under repetitive transient heat loads.

  15. Methane Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Methane (CH4) flux is the net rate of methane exchange between an ecosystem and the atmosphere. Data of this variable were generated by the USGS LandCarbon project...

  16. Developing structural, high-heat flux and plasma facing materials for a near-term DEMO fusion power plant: The EU assessment

    Science.gov (United States)

    Stork, D.; Agostini, P.; Boutard, J. L.; Buckthorpe, D.; Diegele, E.; Dudarev, S. L.; English, C.; Federici, G.; Gilbert, M. R.; Gonzalez, S.; Ibarra, A.; Linsmeier, Ch.; Li Puma, A.; Marbach, G.; Morris, P. F.; Packer, L. W.; Raj, B.; Rieth, M.; Tran, M. Q.; Ward, D. J.; Zinkle, S. J.

    2014-12-01

    The findings of the EU 'Materials Assessment Group' (MAG), within the 2012 EU Fusion Roadmap exercise, are discussed. MAG analysed the technological readiness of structural, plasma facing and high heat flux materials for a DEMO concept to be constructed in the early 2030s, proposing a coherent strategy for R&D up to a DEMO construction decision. A DEMO phase I with a 'Starter Blanket' and 'Starter Divertor' is foreseen: the blanket being capable of withstanding ⩾2 MW yr m-2 fusion neutron fluence (∼20 dpa in the front-wall steel). A second phase ensues for DEMO with ⩾5 MW yr m-2 first wall neutron fluence. Technical consequences for the materials required and the development, testing and modelling programmes, are analysed using: a systems engineering approach, considering reactor operational cycles, efficient maintenance and inspection requirements, and interaction with functional materials/coolants; and a project-based risk analysis, with R&D to mitigate risks from material shortcomings including development of specific risk mitigation materials. The DEMO balance of plant constrains the blanket and divertor coolants to remain unchanged between the two phases. The blanket coolant choices (He gas or pressurised water) put technical constraints on the blanket steels, either to have high strength at higher temperatures than current baseline variants (above 650 °C for high thermodynamic efficiency from He-gas coolant), or superior radiation-embrittlement properties at lower temperatures (∼290-320 °C), for construction of water-cooled blankets. Risk mitigation proposed would develop these options in parallel, and computational and modelling techniques to shorten the cycle-time of new steel development will be important to achieve tight R&D timescales. The superior power handling of a water-cooled divertor target suggests a substructure temperature operating window (∼200-350 °C) that could be realised, as a baseline-concept, using tungsten on a copper

  17. From the subtropics to the equator in the Southwest Pacific: Continental material fluxes quantified using neodymium data along modeled thermocline water pathways

    Science.gov (United States)

    Grenier, Mélanie; Jeandel, Catherine; Cravatte, Sophie

    2014-06-01

    The southwestern tropical Pacific, part of a major pathway for waters feeding the Equatorial Undercurrent, is a region of important geochemical enrichment through land-ocean boundary exchange. Here we develop an original method based on the coupling between dynamical modeling and geochemical tracer data to identify regions of enrichment along the water pathways from the subtropics to the equator, and to allow a refined quantification of continental material fluxes. Neodymium data are interpreted with the help of modeled Lagrangian trajectories of an Ocean General Circulation Model. We reveal that upper and lower thermocline waters have different pathways together with different geochemical evolutions. The upper thermocline waters entering the Solomon Sea mainly originate from the central subtropical gyre, enter the Coral Sea in the North Vanuatu Jet and likely receive radiogenic neodymium from the basaltic island margins encountered along their route. The lower thermocline waters entering the Solomon Sea mainly originate from northeast of New Zealand and enter the Coral Sea in the North Caledonian Jet. Depletion of their neodymium content likely occurs when flowing along the Australian and Papua coasts. Downstream from the Solomon Sea, waters flowing along the Papua New Guinea margins near the Sepik river mouth become surprisingly depleted in their neodymium content in the upper thermocline while enriched in the lower thermocline. This coupled approach is proposed as strong support to interpret the origin of the equatorial Pacific natural fertilization through a better understanding of the circulation, important objectives of the international GEOTRACES and SPICE programs, respectively.

  18. Suspended particulate matter and vertical fluxes of sedimentary material in bays of the Murmansk (Barents Sea) and Karelian (White Sea) coasts

    Science.gov (United States)

    Mityaev, M. V.; Gerasimova, M. V.; Berger, V. Ja.

    2017-03-01

    Synchronous measurement of the total suspended organic and mineral particulate matter, together with vertical sedimentary matter flux, carried out in various areas of Yarnyschnaya Inlet (Murmansk coast of the Barents Sea) and Chupa Inlet (Karelian coast of the White Sea) revealed that the seston organic component plays no part in sedimentation, being almost completely utilized in the water column, while the majority of mineral matter is transported out of the bay. The total amount of suspended matter and its components in the water column is estimated, as well as the total flux of sedimentary matter to the bottom of Chupa and Yarnyschnaya inlets.

  19. First assessment of flux rates of jellyfish carcasses (jelly-falls to the benthos reveals the importance of gelatinous material for biological C-cycling in jellyfish-dominated ecosystems

    Directory of Open Access Journals (Sweden)

    Andrew Kvassnes Sweetman

    2015-07-01

    Full Text Available There is accumulating evidence that jellyfish contribute significantly to biological carbon cycling and that their carcasses can have controversial effects on seafloor ecosystems. Moreover, changes in the thermal properties of the ocean, ocean chemistry and direct anthropogenic effects can seriously modify jellyfish populations in surface waters and potentially alter the importance of jellyfish in the biological pump relative to other forms of detritus. However, no studies have ever quantified the flux rate of jellyfish carcasses (jelly-falls to the seafloor, or quantified how jelly-fall C and N fluxes compare to phytodetrital fluxes. In this study, we documented the seafloor abundance of jelly-falls over a 1-year period in the jellyfish-dominated Lurefjord, western Norway. A total of 9 jelly-falls were documented from 768 seafloor images over the course of the study, equivalent to 0-13.4 mg C m-2 and 0-2.1 mg N m-2 of jellyfish material being deposited in the deep fjord basin. Assuming that jellyfish removal rates and phytodetrital flux rates from nearby fjord environments are similar to Lurefjorden, we estimate that the jellyfish C and N fluxes to the seafloor were 0-72.8 mg C m-2 d-1 and 0-11.2 mg N m-2 d-1 at the time of sampling. In addition, we estimate that the maximum jellyfish carcass flux rates were equivalent to 96 and 160% of the phytodetrital C and N flux that would arrive at the seafloor where the jelly-falls were recorded. These results imply that jelly-falls most likely contribute significantly to detrital C and N fluxes in at least one jellyfish-dominated environment, despite often being recorded in low abundances. If more fjord environments become jellyfish hotspots as a result of water column darkening, the contribution of jellyfish C and N in the biological pump will potentially increase, necessitating the conceptual inclusion of a jelly-pump in future fjord biogeochemical cycling studies.

  20. Materialism.

    Science.gov (United States)

    Melnyk, Andrew

    2012-05-01

    Materialism is nearly universally assumed by cognitive scientists. Intuitively, materialism says that a person's mental states are nothing over and above his or her material states, while dualism denies this. Philosophers have introduced concepts (e.g., realization and supervenience) to assist in formulating the theses of materialism and dualism with more precision, and distinguished among importantly different versions of each view (e.g., eliminative materialism, substance dualism, and emergentism). They have also clarified the logic of arguments that use empirical findings to support materialism. Finally, they have devised various objections to materialism, objections that therefore serve also as arguments for dualism. These objections typically center around two features of mental states that materialism has had trouble in accommodating. The first feature is intentionality, the property of representing, or being about, objects, properties, and states of affairs external to the mental states. The second feature is phenomenal consciousness, the property possessed by many mental states of there being something it is like for the subject of the mental state to be in that mental state. WIREs Cogn Sci 2012, 3:281-292. doi: 10.1002/wcs.1174 For further resources related to this article, please visit the WIREs website. Copyright © 2012 John Wiley & Sons, Ltd.

  1. 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.

  2. Physics of Magnetic Flux Ropes

    CERN Document Server

    Priest, E R; Lee, L C

    1990-01-01

    The American Geophysical Union Chapman Conference on the Physics of Magnetic Flux Ropes was held at the Hamilton Princess Hotel, Hamilton, Bermuda on March 27–31, 1989. Topics discussed ranged from solar flux ropes, such as photospheric flux tubes, coronal loops and prominences, to flux ropes in the solar wind, in planetary ionospheres, at the Earth's magnetopause, in the geomagnetic tail and deep in the Earth's magnetosphere. Papers presented at that conference form the nucleus of this book, but the book is more than just a proceedings of the conference. We have solicited articles from all interested in this topic. Thus, there is some material in the book not discussed at the conference. Even in the case of papers presented at the conference, there is generally a much more detailed and rigorous presentation than was possible in the time allowed by the oral and poster presentations.

  3. 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...... length, step height, and.flux start level. Filtrating 8 kg/m(3) yeast cell suspensions by a vibrating 0.45 x 10(-6) m pore size microfiltration hollow fiber module, critical fluxes from 5.6 x 10(-6) to 1.2 x 10(-5) m/s have been measured using various step lengths from 300 to 1200 seconds. Thus...

  4. Flux-P: Automating Metabolic Flux Analysis

    Directory of Open Access Journals (Sweden)

    Birgitta E. Ebert

    2012-11-01

    Full Text Available Quantitative knowledge of intracellular fluxes in metabolic networks is invaluable for inferring metabolic system behavior and the design principles of biological systems. However, intracellular reaction rates can not often be calculated directly but have to be estimated; for instance, via 13C-based metabolic flux analysis, a model-based interpretation of stable carbon isotope patterns in intermediates of metabolism. Existing software such as FiatFlux, OpenFLUX or 13CFLUX supports experts in this complex analysis, but requires several steps that have to be carried out manually, hence restricting the use of this software for data interpretation to a rather small number of experiments. In this paper, we present Flux-P as an approach to automate and standardize 13C-based metabolic flux analysis, using the Bio-jETI workflow framework. Exemplarily based on the FiatFlux software, it demonstrates how services can be created that carry out the different analysis steps autonomously and how these can subsequently be assembled into software workflows that perform automated, high-throughput intracellular flux analysis of high quality and reproducibility. Besides significant acceleration and standardization of the data analysis, the agile workflow-based realization supports flexible changes of the analysis workflows on the user level, making it easy to perform custom analyses.

  5. Properties of Water Bound in Hydrogels

    Directory of Open Access Journals (Sweden)

    Vladimir M. Gun’ko

    2017-10-01

    Full Text Available In this review, the importance of water in hydrogel (HG properties and structure is analyzed. A variety of methods such as 1H NMR (nuclear magnetic resonance, DSC (differential scanning calorimetry, XRD (X-ray powder diffraction, dielectric relaxation spectroscopy, thermally stimulated depolarization current, quasi-elastic neutron scattering, rheometry, diffusion, adsorption, infrared spectroscopy are used to study water in HG. The state of HG water is rather non-uniform. According to thermodynamic features of water in HG, some of it is non-freezing and strongly bound, another fraction is freezing and weakly bound, and the third fraction is non-bound, free water freezing at 0 °C. According to structural features of water in HG, it can be divided into two fractions with strongly associated and weakly associated waters. The properties of the water in HG depend also on the amounts and types of solutes, pH, salinity, structural features of HG functionalities.

  6. Effects of silvicultural management intensity on fluxes of dissolved and particulate organic matter in 27 forest sites of the Biodiversity Exploratories

    Science.gov (United States)

    Michalzik, Beate; Bischoff, Sebastian; Levia, Delphis; Schwarz, Martin; Escher, Peter; Wilcke, Wolfgang; Thieme, Lisa; Kerber, Katja; Kaupenjohann, Martin; Siemens, Jan

    2017-04-01

    In forested ecosystems, throughfall and stemflow function as key components in the cycling of water and associated biogeochemistry. Analysing annual flux data collected from 27 intensively monitored forest sites of the Biodiversity Exploratories, we found throughfall fluxes of DOC (dissolved organic carbon) linearly related (R2 = 0.40, p losses of DOC and POC from the litter layer of forests increased significantly with increasing forest management intensity. The observed relationships revealed by intensive flux monitoring are important because they allow us to link organic matter fluxes to forest metrics of larger forested areas (e.g. derived from LiDAR imagery), and hence to model and up-scale water-bound OC dynamics to the landscape level.

  7. 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.

  8. A time-varying magnetic flux concentrator

    Science.gov (United States)

    Kibret, B.; Premaratne, M.; Lewis, P. M.; Thomson, R.; Fitzgerald, P. B.

    2016-08-01

    It is known that diverse technological applications require the use of focused magnetic fields. This has driven the quest for controlling the magnetic field. Recently, the principles in transformation optics and metamaterials have allowed the realization of practical static magnetic flux concentrators. Extending such progress, here, we propose a time-varying magnetic flux concentrator cylindrical shell that uses electric conductors and ferromagnetic materials to guide magnetic flux to its center. Its performance is discussed based on finite-element simulation results. Our proposed design has potential applications in magnetic sensors, medical devices, wireless power transfer, and near-field wireless communications.

  9. Electron heat flux instability

    Science.gov (United States)

    Saeed, Sundas; Sarfraz, M.; Yoon, P. H.; Lazar, M.; Qureshi, M. N. S.

    2017-02-01

    The heat flux instability is an electromagnetic mode excited by a relative drift between the protons and two-component core-halo electrons. The most prominent application may be in association with the solar wind where drifting electron velocity distributions are observed. The heat flux instability is somewhat analogous to the electrostatic Buneman or ion-acoustic instability driven by the net drift between the protons and bulk electrons, except that the heat flux instability operates in magnetized plasmas and possesses transverse electromagnetic polarization. The heat flux instability is also distinct from the electrostatic counterpart in that it requires two electron species with relative drifts with each other. In the literature, the heat flux instability is often called the 'whistler' heat flux instability, but it is actually polarized in the opposite sense to the whistler wave. This paper elucidates all of these fundamental plasma physical properties associated with the heat flux instability starting from a simple model, and gradually building up more complexity towards a solar wind-like distribution functions. It is found that the essential properties of the instability are already present in the cold counter-streaming electron model, and that the instability is absent if the protons are ignored. These instability characteristics are highly reminiscent of the electron firehose instability driven by excessive parallel temperature anisotropy, propagating in parallel direction with respect to the ambient magnetic field, except that the free energy source for the heat flux instability resides in the effective parallel pressure provided by the counter-streaming electrons.

  10. 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...

  11. Net Ecosystem Carbon Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Net Ecosystem Carbon Flux is defined as the year-over-year change in Total Ecosystem Carbon Stock, or the net rate of carbon exchange between an ecosystem and the...

  12. Nitrous Oxide Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Nitrous Oxide (N20) flux is the net rate of nitrous oxide exchange between an ecosystem and the atmosphere. Data of this variable were generated by the USGS...

  13. 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

  14. Flux Emergence (Theory

    Directory of Open Access Journals (Sweden)

    Mark C. M. Cheung

    2014-07-01

    Full Text Available 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.

  15. Generic flux coupling analysis

    OpenAIRE

    Reimers, Arne; Goldstein, Y.; Bockmayr, A.

    2015-01-01

    htmlabstractFlux coupling analysis (FCA) has become a useful tool for aiding metabolic reconstructions and guiding genetic manipulations. Originally, it was introduced for constraint-based models of metabolic networks that are based on the steady-state assumption. Recently, we have shown that the steady-state assumption can be replaced by a weaker lattice-theoretic property related to the supports of metabolic fluxes. In this paper, we further extend our approach and develop an efficient algo...

  16. The flux-flux correlation function for anharmonic barriers

    NARCIS (Netherlands)

    Goussev, Arseni; Schubert, Roman; Waalkens, Holger; Wiggins, Stephen

    2010-01-01

    The flux-flux correlation function formalism is a standard and widely used approach for the computation of reaction rates. In this paper we introduce a method to compute the classical and quantum flux-flux correlation functions for anharmonic barriers essentially analytically through the use of the

  17. Flux Pinning in Superconductors

    CERN Document Server

    Matsushita, Teruo

    2007-01-01

    The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, high-Tc and MgB2 superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial Nb pins in Nb-Ti, etc., are introduced for the pinning mechanism. Summation theories to derive the critical current density are discussed in detail. Irreversible magnetization and AC loss caused by the flux pinning are also discussed. The loss originally stems from the ohmic dissipation of normal electrons in the normal core driven by the electric field induced by the flux motion. The readers will learn why the resultant loss is of hysteresis type in spite of such mechanism. The influence of the flux pinning on the vortex phase diagram in high Tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of supercondu...

  18. INNOVATIVE HEAT FLUX SENSOR

    Directory of Open Access Journals (Sweden)

    G. N. Lukyanov

    2017-02-01

    Full Text Available Subject of Study.We present a method for heat flux measuring with the use of polarization properties of ferroelectric ceramics. Heat flux innovative sensor is developed on the basis of the proposed method. Its experimental verification is carried out. Method. The measurements are based on maintaining a balance between the processes caused by thermal energy and the energy of the electric field in the ferroelectric ceramics. Main Results. The testing of the proposed heat flux sensor has been organized in two stages. At the first stage the primary calibration has been performed by calibrated sensors ITP MG4.03/x(y “Potok”. At the second stage the testing of heat flux sensor has been carried out for calculating the quantity of heat. The comparison of the results to the readings of serial heat meters VKT-7 and STK-15 has been performed. Experiments have shown that the polarization properties of the ferroelectric ceramics can be used to measure the heat flow. Practical Relevance. The proposed sensor can be recommended as an apartment-level heat meter. The calibration of the proposed heat flux sensor with more accurate measurement tools gives the possibility to include it on the State Register of Measuring Instruments.

  19. Flux pinning in superconductors

    CERN Document Server

    Matsushita, Teruo

    2014-01-01

    The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, high-Tc and MgB2 superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial Nb pins in Nb-Ti, etc., are introduced for the pinning mechanism. Summation theories to derive the critical current density are discussed in detail. Irreversible magnetization and AC loss caused by the flux pinning are also discussed. The loss originally stems from the ohmic dissipation of normal electrons in the normal core driven by the electric field induced by the flux motion. The readers will learn why the resultant loss is of hysteresis type in spite of such mechanism. The influence of the flux pinning on the vortex phase diagram in high Tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of supercondu...

  20. Generic flux coupling analysis

    NARCIS (Netherlands)

    A.C. Reimers (Arne); Y. Goldstein; A. Bockmayr

    2015-01-01

    htmlabstractFlux coupling analysis (FCA) has become a useful tool for aiding metabolic reconstructions and guiding genetic manipulations. Originally, it was introduced for constraint-based models of metabolic networks that are based on the steady-state assumption. Recently, we have shown that the

  1. Flux Vacua and Supermanifolds

    CERN Document Server

    Grassi, P A

    2007-01-01

    As been recently pointed out, physically relevant models derived from string theory require the presence of non-vanishing form fluxes besides the usual geometrical constraints. In the case of NS-NS fluxes, the Generalized Complex Geometry encodes these informations in a beautiful geometrical structure. On the other hand, the R-R fluxes call for supergeometry as the underlying mathematical framework. In this context, we analyze the possibility of constructing interesting supermanifolds recasting the geometrical data and RR fluxes. To characterize these supermanifolds we have been guided by the fact topological strings on supermanifolds require the super-Ricci flatness of the target space. This can be achieved by adding to a given bosonic manifold enough anticommuting coordinates and new constraints on the bosonic sub-manifold. We study these constraints at the linear and non-linear level for a pure geometrical setting and in the presence of p-form field strengths. We find that certain spaces admit several supe...

  2. 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,...

  3. Generic flux coupling analysis.

    Science.gov (United States)

    Reimers, Arne C; Goldstein, Yaron; Bockmayr, Alexander

    2015-04-01

    Flux coupling analysis (FCA) has become a useful tool for aiding metabolic reconstructions and guiding genetic manipulations. Originally, it was introduced for constraint-based models of metabolic networks that are based on the steady-state assumption. Recently, we have shown that the steady-state assumption can be replaced by a weaker lattice-theoretic property related to the supports of metabolic fluxes. In this paper, we further extend our approach and develop an efficient algorithm for generic flux coupling analysis that works with any kind of qualitative pathway model. We illustrate our method by thermodynamic flux coupling analysis (tFCA), which allows studying steady-state metabolic models with loop-law thermodynamic constraints. These models do not satisfy the lattice-theoretic properties required in our previous work. For a selection of genome-scale metabolic network reconstructions, we discuss both theoretically and practically, how thermodynamic constraints strengthen the coupling results that can be obtained with classical FCA. A prototype implementation of tFCA is available at http://hoverboard.io/L4FC. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Triode for magnetic flux quanta.

    Science.gov (United States)

    Vlasko-Vlasov, Vitalii; Colauto, Fabiano; Benseman, Timothy; Rosenmann, Daniel; Kwok, Wai-Kwong

    We designed a magnetic vortex triode using an array of closely spaced soft magnetic Py strips on top of a Nb superconducting film. The strips act similar to the grid electrode in an electronic triode, where the electron flow is regulated by the grid potential. In our case, we tune the vortex motion by the magnetic charge potential of the strip edges, using a small magnetic field rotating in the film plane. The magnetic charges emerging at the stripe edges and proportional to the magnetization component perpendicular to the edge direction, form linear potential barriers or valleys for vortex motion in the superconducting layer. We directly imaged the normal flux penetration into the Py/Nb films and observed retarded or accelerated entry of the normal vortices depending on the in-plane magnetization direction in the stripes. The observed flux behavior is explained by interactions between magnetically charged lines and magnetic monopoles of vortices similar to those between electrically charged strings and point charges. We discuss the possibility of using our design for manipulation of individual vortices in high-speed, low-power superconducting electronic circuits. This work was supported by the U.S. DOE, Office of Science, Materials Sciences and Engineering Division, and Office of BES (contract DE-AC02-06CH11357). F. Colauto thanks the Sao Paulo Research Foundation FAPESP (Grant No. 2015/06.085-3).

  5. Dynamic ignition regime of condensed system by radiate heat flux

    Science.gov (United States)

    Arkhipov, V. A.; Zolotorev, N. N.; Korotkikh, A. G.; Kuznetsov, V. T.

    2017-05-01

    The main ignition characteristics of high-energy materials are the ignition time and critical heat flux allowing evaluation of the critical conditions for ignition, fire and explosive safety for the test solid propellants. The ignition process is typically studied in stationary conditions of heat input at constant temperature of the heating surface, environment or the radiate heat flux on the sample surface. In real conditions, ignition is usually effected at variable time-dependent values of the heat flux. In this case, the heated layer is formed on the sample surface in dynamic conditions and significantly depends on the heat flux change, i.e. increasing or decreasing falling heat flux in the reaction period of the propellant sample. This paper presents a method for measuring the ignition characteristics of a high-energy material sample in initiation of the dynamic radiant heat flux, which includes the measurement of the ignition time when exposed to a sample time varying radiant heat flux given intensity. In case of pyroxyline containing 1 wt. % of soot, it is shown that the ignition times are reduced by 20-50 % depending on the initial value of the radiant flux density in initiation by increasing or decreasing radiant heat flux compared with the stationary conditions of heat supply in the same ambient conditions.

  6. Quasi-One-Dimensional Intermittent Flux Behavior in Superconducting Films

    Directory of Open Access Journals (Sweden)

    A. J. Qviller

    2012-01-01

    Full Text Available Intermittent filamentary dynamics of the vortex matter in superconductors is found in films of YBa_{2}Cu_{3}O_{7-δ} deposited on tilted substrates. Deposition of this material on such substrates creates parallel channels of easy flux penetration when a magnetic field is applied perpendicular to the film. As the applied field is gradually increased, magneto-optical imaging reveals that flux penetrates via numerous quasi-one-dimensional jumps. The distribution of flux avalanche sizes follows a power law, and data collapse is obtained by finite-size scaling, with the depth of the flux front used as crossover length. The intermittent behavior shows no threshold value in the applied field, in contrast to conventional flux jumping. The results strongly suggest that the quasi-one-dimensional flux jumps are of a different nature than the thermomagnetic dendritic (branching avalanches that are commonly found in superconducting films.

  7. Quasi-one-dimensional intermittent flux behavior in superconducting films

    DEFF Research Database (Denmark)

    Qviller, A. J.; Yurchenko, V. V.; Galperin, Y. M.

    2012-01-01

    Intermittent filamentary dynamics of the vortex matter in superconductors is found in films of YBa2Cu3O7-δ deposited on tilted substrates. Deposition of this material on such substrates creates parallel channels of easy flux penetration when a magnetic field is applied perpendicular to the film....... As the applied field is gradually increased, magneto-optical imaging reveals that flux penetrates via numerous quasi-one-dimensional jumps. The distribution of flux avalanche sizes follows a power law, and data collapse is obtained by finite-size scaling, with the depth of the flux front used as crossover length....... The intermittent behavior shows no threshold value in the applied field, in contrast to conventional flux jumping. The results strongly suggest that the quasi-one-dimensional flux jumps are of a different nature than the thermomagnetic dendritic (branching) avalanches that are commonly found in superconducting...

  8. 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.

  9. 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.

  10. Upland Forest Linkages to Seasonal Wetlands: Litter Flux, Processing, and Food Quality

    Science.gov (United States)

    Brian J. Palik; Darold P. Batzer; Christel Kern

    2005-01-01

    The flux of materials across ecosystem boundaries has significant effects on recipient systems. Because of edge effects, seasonal wetlands in upland forest are good systems to explore these linkages. The purpose of this study was to examine flux of coarse particulate organic matter as litter fall into seasonal wetlands in Minnesota, and the relationship of this flux to...

  11. HTS flux flow devices and applications

    Energy Technology Data Exchange (ETDEWEB)

    Martens, J.; Pance, A.; Johansson, M.; Char, K.; Whiteley, S. [Conductus, Sunnyvale, CA (United States); Hou, S.; Phillips, J. [AT and T Bell Labs., Murray Hill, NJ (United States)

    1994-12-31

    Flux flow devices are three terminal active superconducting elements. Among the circuits demonstrated are mm-wave amplifiers, a fairly complete logic family and multiplexers/demultiplexers. Before it can be decided if this technology is viable for circuits of sufficient complexity to be commercially interesting, many manufacturability and materials questions must be answered. Work pertaining to these questions as well as demonstrations to date will be discussed.

  12. 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.

  13. On deriving flux freezing in magnetohydrodynamics by direct differentiation

    Science.gov (United States)

    Blackman, Eric G.

    2013-03-01

    The magnetic flux freezing theorem is a basic principle of ideal magnetohydrodynamics (MHD), a commonly used approximation to describe the aspects of astrophysical and laboratory plasmas. The theorem states that the magnetic flux—the integral of magnetic field penetrating a surface—is conserved in time as that surface is distorted in time by fluid motions. Pedagogues of MHD commonly derive flux freezing without showing how to take the material derivative of a general flux integral and/or assuming a vanishing field divergence from the outset. Here I avoid these shortcomings and derive flux freezing by direct differentiation, explicitly using a Jacobian to transform between the evolving field-penetrating surface at different times. The approach is instructive for its generality and helps elucidate the role of magnetic monopoles in breaking flux freezing. The paucity of appearances of this derivation in standard MHD texts suggests that its pedagogic value is underappreciated.

  14. Optimal fluxes and Reynolds stresses

    CERN Document Server

    Jimenez, Javier

    2016-01-01

    It is remarked that fluxes in conservation laws, such as the Reynolds stresses in the momentum equation of turbulent shear flows, or the spectral energy flux in isotropic turbulence, are only defined up to an arbitrary solenoidal field. While this is not usually significant for long-time averages, it becomes important when fluxes are modelled locally in large-eddy simulations, or in the analysis of intermittency and cascades. As an example, a numerical procedure is introduced to compute fluxes in scalar conservation equations in such a way that their total integrated magnitude is minimised. The result is an irrotational vector field that derives from a potential, thus minimising sterile flux `circuits'. The algorithm is generalised to tensor fluxes and applied to the transfer of momentum in a turbulent channel. The resulting instantaneous Reynolds stresses are compared with their traditional expressions, and found to be substantially different.

  15. Graphene thermal flux transistor.

    Science.gov (United States)

    Shafranjuk, S E

    2016-11-24

    Insufficient flexibility of existing approaches to controlling the thermal transport in atomic monolayers limits their capability for use in many applications. Here, we examine the means of electrode doping to control the thermal flux Q due to phonons propagating along the atomic monolayer. We found that the frequency of the electron-restricted phonon scattering strongly depends on the concentration nC. of the electric charge carriers, established by the electric potentials applied to local gates. As a result of the electrode doping, nC is increased, causing a sharp rise in both the electrical conductivity and Seebeck coefficient, while the thermal conductivity tumbles. Therefore, the effect of the thermal transistor improves the figure of merit of nanoelectronic circuits.

  16. 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.

  17. 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....

  18. Methane flux from wetlands areas

    OpenAIRE

    BAKER-BLOCKER, ANITA; DONAHUE, THOMAS M.; MANCY, KHALIL H.

    2011-01-01

    Ebullient gases from Michigan wetlands have been collected and analyzed to deduce in situ methane fluxes. Methane flux has been found to be a function of mean air temperature. This relationship has been utilized to extrapolate observed methane fluxes to estimates of fluxes from the Pripet marshes, Sudd, Everglades, and Ugandan swamps. These four wetlands together provide a yearly source of 6.8 × 1013 g of methane to the atmosphere.DOI: 10.1111/j.2153-3490.1977.tb00731.x

  19. 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

  20. 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...

  1. Earth's surface heat flux

    Directory of Open Access Journals (Sweden)

    J. H. Davies

    2010-02-01

    Full Text Available We present a revised estimate of Earth's surface heat flux that is based upon a heat flow data-set with 38 347 measurements, which is 55% more than used in previous estimates. Our methodology, like others, accounts for hydrothermal circulation in young oceanic crust by utilising a half-space cooling approximation. For the rest of Earth's surface, we estimate the average heat flow for different geologic domains as defined by global digital geology maps; and then produce the global estimate by multiplying it by the total global area of that geologic domain. The averaging is done on a polygon set which results from an intersection of a 1 degree equal area grid with the original geology polygons; this minimises the adverse influence of clustering. These operations and estimates are derived accurately using methodologies from Geographical Information Science. We consider the virtually un-sampled Antarctica separately and also make a small correction for hot-spots in young oceanic lithosphere. A range of analyses is presented. These, combined with statistical estimates of the error, provide a measure of robustness. Our final preferred estimate is 47±2 TW, which is greater than previous estimates.

  2. Flow instabilities of magnetic flux tubes. IV. Flux storage in the solar overshoot region

    Science.gov (United States)

    Işık, E.; Holzwarth, V.

    2009-12-01

    Context: Flow-induced instabilities of magnetic flux tubes are relevant to the storage of magnetic flux in the interiors of stars with outer convection zones. The stability of magnetic fields in stellar interiors is of importance to the generation and transport of solar and stellar magnetic fields. Aims: We consider the effects of material flows on the dynamics of toroidal magnetic flux tubes located close to the base of the solar convection zone, initially within the overshoot region. The problem is to find the physical conditions in which magnetic flux can be stored for periods comparable to the dynamo amplification time, which is of the order of a few years. Methods: We carry out nonlinear numerical simulations to investigate the stability and dynamics of thin flux tubes subject to perpendicular and longitudinal flows. We compare the simulations with the results of simplified analytical approximations. Results: The longitudinal flow instability induced by the aerodynamic drag force is nonlinear in the sense that the growth rate depends on the perturbation amplitude. This result is consistent with the predictions of linear theory. Numerical simulations without friction show that nonlinear Parker instability can be triggered below the linear threshold of the field strength, when the difference in superadiabaticity along the tube is sufficiently large. A localised downflow acting on a toroidal tube in the overshoot region leads to instability depending on the parameters describing the flow, as well as the magnetic field strength. We determined ranges of the flow parameters for which a linearly Parker-stable magnetic flux tube is stored in the middle of the overshoot region for a period comparable to the dynamo amplification time. Conclusions: The longitudinal flow instability driven by frictional interaction of a flux tube with its surroundings is relevant to determining the storage time of magnetic flux in the solar overshoot region. The residence time for

  3. 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.

  4. High flux expansion divertor studies in NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Soukhanovskii, V A; Maingi, R; Bell, R E; Gates, D A; Kaita, R; Kugel, H W; LeBlanc, B P; Maqueda, R; Menard, J E; Mueller, D; Paul, S F; Raman, R; Roquemore, A L

    2009-06-29

    Projections for high-performance H-mode scenarios in spherical torus (ST)-based devices assume low electron collisionality for increased efficiency of the neutral beam current drive. At lower collisionality (lower density), the mitigation techniques based on induced divertor volumetric power and momentum losses may not be capable of reducing heat and material erosion to acceptable levels in a compact ST divertor. Divertor geometry can also be used to reduce high peak heat and particle fluxes by flaring a scrape-off layer (SOL) flux tube at the divertor plate, and by optimizing the angle at which the flux tube intersects the divertor plate, or reduce heat flow to the divertor by increasing the length of the flux tube. The recently proposed advanced divertor concepts [1, 2] take advantage of these geometry effects. In a high triangularity ST plasma configuration, the magnetic flux expansion at the divertor strike point (SP) is inherently high, leading to a reduction of heat and particle fluxes and a facilitated access to the outer SP detachment, as has been demonstrated recently in NSTX [3]. The natural synergy of the highly-shaped high-performance ST plasmas with beneficial divertor properties motivated a further systematic study of the high flux expansion divertor. The National Spherical Torus Experiment (NSTX) is a mid-sized device with the aspect ratio A = 1.3-1.5 [4]. In NSTX, the graphite tile divertor has an open horizontal plate geometry. The divertor magnetic configuration geometry was systematically changed in an experiment by either (1) changing the distance between the lower divertor X-point and the divertor plate (X-point height h{sub X}), or by (2) keeping the X-point height constant and increasing the outer SP radius. An initial analysis of the former experiment is presented below. Since in the divertor the poloidal field B{sub {theta}} strength is proportional to h{sub X}, the X-point height variation changed the divertor plasma wetted area due to

  5. Area monitoring in a deposit of radioactive material: high flux air sampling for determination of long half-life alpha emitters; Monitoracao de area em um deposito de material radioativo: amostragem de ar de alto fluxo para determinacao de alfa emissores de meia vida longa

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Wagner de S.; Py Junior, Delcy de A.; Dores, Luis A. de C.B.; Antunes, Ana Claudia da Silva; Garcia Filho, Oswaldo; Oliveira, Sergio Quinet de; Dantas, Marcelino V.A. [Industrias Nucleares do Brasil (UTM/INB), Pocos de Caldas, MG (Brazil). Unidade de Tratamento de Minerio; Kelecom, Alphonse, E-mail: wspereira@inb.gov.b, E-mail: delcy@inb.gov.b, E-mail: luisdores@inb.gov.b, E-mail: anasilva@inb.gov.b, E-mail: sergioquinet@inb.gov.b, E-mail: Marcelino@inb.gov.b [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Biologia. Lab. de Radiobiologia e Radiometria Pedro Lopes dos Santos

    2011-10-26

    The present paper presents the program of high-flux monitoring and the results obtained in the year 2009. The derivative limit (LD) of air concentration was of 0.25 Bq/m{sup 3}. The permanence control is a important factor in the occupational control of workers, and also the use of EPs the behavioural cares, and the radioprotection training for allowing the access to those areas. Neither workers, inspector nor visitors reached the limit of investigation

  6. Production of fullerenes with concentrated solar flux

    Energy Technology Data Exchange (ETDEWEB)

    Hale, M. J.; Fields, C.; Lewandowski, A.; Bingham, C.; Pitts, R.

    1994-01-01

    Research at the National Renewable Energy Laboratory (NREL) has demonstrated that fullerenes can be produced using highly concentrated sunlight from a solar furnace. Since they were first synthesized in 1989, fullerenes have been the subject of intense research. They show considerable commercial potential in advanced materials and have potential applications that include semiconductors, superconductors, high-performance metals, and medical technologies. The most common fullerene is C{sub 60}, which is a molecule with a geometry resembling a soccer ball. Graphite vaporization methods such as pulsed-laser vaporization, resistive heating, and carbon arc have been used to produce fullerenes. None of these, however, seems capable of producing fullerenes economically on a large scale. The use of concentrated sunlight may help avoid the scale-up limitations inherent in more established production processes. Recently, researchers at NREL made fullerenes in NREL`s 10 kW High Flux Solar Furnace (HFSF) with a vacuum reaction chamber designed to deliver a solar flux of 1200 W/cm{sup 2} to a graphite pellet. Analysis of the resulting carbon soot by mass spectrometry and high-pressure liquid chromatography confirmed the existence of fullerenes. These results are very encouraging and we are optimistic that concentrated solar flux can provide a means for large-scale, economical production of fullerenes. This paper presents our method, experimental apparatus, and results of fullerene production research performed with the HFSF.

  7. 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.

  8. 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...

  9. 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.

  10. P fluxes and exotic branes

    Energy Technology Data Exchange (ETDEWEB)

    Lombardo, Davide M. [Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy); Riccioni, Fabio [INFN - Sezione di Roma, Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy); Risoli, Stefano [Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy); INFN - Sezione di Roma, Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy)

    2016-12-21

    We consider the N=1 superpotential generated in type-II orientifold models by non-geometric fluxes. In particular, we focus on the family of P fluxes, that are related by T-duality transformations to the S-dual of the Q flux. We determine the general rule that transforms a given flux in this family under a single T-duality transformation. This rule allows to derive a complete expression for the superpotential for both the IIA and the IIB theory for the particular case of a T{sup 6}/[ℤ{sub 2}×ℤ{sub 2}] orientifold. We then consider how these fluxes modify the generalised Bianchi identities. In particular, we derive a fully consistent set of quadratic constraints coming from the NS-NS Bianchi identities. On the other hand, the P flux Bianchi identities induce tadpoles, and we determine a set of exotic branes that can be consistently included in order to cancel them. This is achieved by determining a universal transformation rule under T-duality satisfied by all the branes in string theory.

  11. 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.

  12. Marginal Ice Zone Flux and Variability

    Science.gov (United States)

    Pfirman, S. L.; Tremblay, B.; Newton, R.; Fowler, C.

    2009-12-01

    Arctic sea ice acts as a conveyor, collecting and transporting material across the central basin, and releasing it in the marginal ice zone (MIZ). Where and when ice with different transport histories melts, has a large impact on the MIZ and is critical for understanding the vulnerability of the Arctic system to climate change. This study focuses on the effects of changing the location and timing of fluxes to the MIZ, as well as the age and origin of ice delivered there. Combining observations and models, we analyze sea ice motion for origin, age, drift path, and flux (both along the drift path and to the MIZ) for past, recent, and future scenarios. We examine temporal and spatial variations in the transport of sea ice and ice-rafted material between different source and melt regions for interannual and seasonal variability, including: a) How the distribution, origin, and age of ice delivered to various MIZs has changed over time, especially during the spring bloom. b) How changes in ice drift related to changes in atmospheric, oceanic, sedimentologic, and ecologic conditions have influenced the delivery of freshwater, sediments, and biological material. c) How changes have varied regionally and with respect to water depth. For example, whether maximum ice melt - and therefore material release - occurs over deep waters or shallow shelves is an important ecological parameter. As the Arctic transitions toward ice free summer conditions, the seasonal ice zone will expand, shifting the location of the marginal ice zone. It is critical to understand processes governing these changes because the MIZ is the most dynamic, most productive, and most vulnerable region in the Arctic.

  13. Lithogenic fluxes to the northern Indian Ocean - An overview

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.

    Lithogenic fluxes to the northern Indian Ocean, measurEd. by time-series sediment traps, exhibit a strong seasonality with the bulk of the material (40 to 80 %) being deposited during the southwest monsoon period. This seasonality is more pronounced...

  14. Circumstellar disc geometry constrained by infrared line fluxes

    NARCIS (Netherlands)

    Jones, C.E.; Molak, A.; Sigut, T.A.A.; de Koter, A.; Lenorzer, A.; Popa, S.C.

    2009-01-01

    Lenorzer et al. introduce ratios of hydrogen infrared recombination lines as a diagnostic tool to constrain the spatial distribution and physical condition of circumstellar material around hot massive stars. They demonstrate that the observed line flux ratios Hu14/Brα and Hu14/Pfγ from different

  15. Effect of fluxing additive on sintering temperature, microstructure and ...

    Indian Academy of Sciences (India)

    The persistence of various phase(s) at higher temperatures in the flux-added materials indicated that the phase transitions occurred relatively slowly. A decrease in dielectric constant of Li2O-added BaTiO3 in comparison to pure BaTiO3 may be due to the diminished dielectric polarizability of Li+ in comparison to Ba2+.

  16. Numerical study on AC loss reduction of stacked HTS tapes by optimal design of flux diverter

    Science.gov (United States)

    Liu, Guole; Zhang, Guomin; Jing, Liwei; Yu, Hui

    2017-12-01

    High temperature superconducting (HTS) coils are key parts of many AC applications, such as generators, superconducting magnetic energy storage and transformers. AC loss reduction in HTS coils is essential for the commercialization of these HTS devices. Magnetic material is generally used as the flux diverter in an effort to reduce the AC loss in HTS coils. To achieve the greatest reduction in the AC loss of the coils, the flux diverter should be made of a material with low loss and high saturated magnetic density, and the optimization of the geometric size and location of the flux diverter is required. In this paper, we chose Ni-alloy as the flux diverter, which can be processed into a specific shape and size. The influence of the shape and location of the flux diverter on the AC loss characteristics of stacked (RE)BCO tapes is investigated by use of a finite element method. Taking both the AC loss of the (RE)BCO coils and the ferromagnetic loss of the flux diverter into account, the optimal geometry of the flux diverter is obtained. It is found that when the applied current is at half the value of the critical current, the total loss of the HTS stack with the optimal flux diverter is only 18% of the original loss of the HTS stack without the flux diverter. Besides, the effect of the flux diverter on the critical current of the (RE)BCO stack is investigated.

  17. Two fluxes multistage induction coilgun

    Science.gov (United States)

    Gherman, L.; Pearsica, M.; Circiu, I.; Rotaru, C.

    2017-05-01

    This paper presents a brand new induction electromagnetic launcher, which uses two magnetic fluxes in order to accelerate a projectile. One magnetic flux induce a current in the armature and the second magnetic flux is creating a radial magnetic field. This aproach offer multiple advantages over single flux designs. First we are able to control the induced current in armature because we use the coil just to induce current inside the ring with a great efficiency. Second advantage is the angle of 900 between magnetic field density B and the ring. We used the induction to avoid contact between armature and accelerator. In order to create the magnetic field radial we used four coils perpendicular on armature. This approach alove us to control the phase difference between induced current in armature and current in magnetic field coils for a maximum force. The phase difference is obtained by changing the frequency of magnetic field coils power source. We used simulation software to analyze, and simulate a multistage induction coilgun design with two fluxes. The simulation results demonstrated the theoretical results.

  18. 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...

  19. Neutrino Flux Prediction for the NuMI Beamline

    Energy Technology Data Exchange (ETDEWEB)

    Soplin, Leonidas Aliaga [Coll. William and Mary

    2016-01-01

    The determination of the neutrino flux in any conventional neutrino beam presents a challenge for the current and future short and long baseline neutrino experiments. The uncertainties associated with the production and attenuation of the hadrons in the beamline materials along with those associated with the beam optics have a big effect in the flux spectrum knowledge. For experiments like MINERvA, understanding the flux is crucial since it enters directly into every neutrino-nucleus cross-sections measurements. The foundation of this work is predicting the neutrino flux at MINERvA using dedicated measurements of hadron production in hadron-nucleus collisions and incorporating in-situ MINERvA data that can provide additional constraints. This work also includes the prospect for predicting the flux at other detectors like the NOvA Near detector. The procedure and conclusions of this thesis will have a big impact on future hadron production experiments and on determining the flux for the upcoming DUNE experiment.

  20. PROTOSTELLAR ACCRETION FLOWS DESTABILIZED BY MAGNETIC FLUX REDISTRIBUTION

    Energy Technology Data Exchange (ETDEWEB)

    Krasnopolsky, Ruben; Shang, Hsien [Academia Sinica, Institute of Astronomy and Astrophysics, Taipei, Taiwan (China); Li Zhiyun; Zhao Bo [University of Virginia, Astronomy Department, Charlottesville (United States)

    2012-09-20

    Magnetic flux redistribution lies at the heart of the problem of star formation in dense cores of molecular clouds that are magnetized to a realistic level. If all of the magnetic flux of a typical core were to be dragged into the central star, the stellar field strength would be orders of magnitude higher than the observed values. This well-known magnetic flux problem can in principle be resolved through non-ideal MHD effects. Two-dimensional (axisymmetric) calculations have shown that ambipolar diffusion, in particular, can transport magnetic flux outward relative to matter, allowing material to enter the central object without dragging the field lines along. We show through simulations that such axisymmetric protostellar accretion flows are unstable in three dimensions to magnetic interchange instability in the azimuthal direction. The instability is driven by the magnetic flux redistributed from the matter that enters the central object. It typically starts to develop during the transition from the prestellar phase of star formation to the protostellar mass accretion phase. In the latter phase, the magnetic flux is transported outward mainly through advection by strongly magnetized low-density regions that expand against the collapsing inflow. The tussle between the gravity-driven infall and magnetically driven expansion leads to a highly filamentary inner accretion flow that is more disordered than previously envisioned. The efficient outward transport of magnetic flux by advection lowers the field strength at small radii, making the magnetic braking less efficient and the formation of rotationally supported disks easier in principle. However, we find no evidence for such disks in any of our rotating collapse simulations. We conclude that the inner protostellar accretion flow is shaped to a large extent by the flux redistribution-driven magnetic interchange instability. How disks form in such an environment is unclear.

  1. Gaseous Oxidized Mercury Flux from Substrates Associated with Industrial Scale Gold Mining in Nevada, USA

    Science.gov (United States)

    Miller, M. B.

    2015-12-01

    Gaseous elemental and oxidized mercury (Hg) fluxes were measured in a laboratory setting from substrate materials derived from industrial-scale open pit gold mining operations in Nevada, USA. Mercury is present in these substrates at a range of concentrations (10 - 40000 ng g-1), predominantly of local geogenic origin in association with the mineralized gold ores, but altered and redistributed to a varying degree by subsequent ore extraction and processing operations, including deposition of Hg recently emitted to the atmosphere from large point sources on the mines. Waste rock, heap leach, and tailings material usually comprise the most extensive and Hg emission relevant substrate surfaces. All three of these material types were collected from active Nevada mine sites in 2010 for previous research, and have since been stored undisturbed at the University of Nevada, Reno. Gaseous elemental Hg (GEM) flux was previously measured from these materials under a variety of conditions, and was re-measured in this study, using Teflon® flux chambers and Tekran® 2537A automated ambient air analyzers. GEM flux from dry undisturbed materials was comparable between the two measurement periods. Gaseous oxidized Hg (GOM) flux from these materials was quantified using an active filter sampling method that consisted of polysulfone cation-exchange membranes deployed in conjunction with the GEM flux apparatus. Initial measurements conducted within greenhouse laboratory space indicate that in dry conditions GOM is deposited to relatively low Hg cap and leach materials, but may be emitted from the much higher Hg concentration tailings material.

  2. Reconnecting flux-rope dynamo.

    Science.gov (United States)

    Baggaley, Andrew W; Barenghi, Carlo F; Shukurov, Anvar; Subramanian, Kandaswamy

    2009-11-01

    We develop a model of the fluctuation dynamo in which the magnetic field is confined to thin flux ropes advected by a multiscale model of turbulence. Magnetic dissipation occurs only via reconnection of the flux ropes. This model can be viewed as an implementation of the asymptotic limit R_{m}-->infinity for a continuous magnetic field, where magnetic dissipation is strongly localized to small regions of strong-field gradients. We investigate the kinetic-energy release into heat mediated by the dynamo action, both in our model and by solving the induction equation with the same flow. We find that a flux-rope dynamo is an order of magnitude more efficient at converting mechanical energy into heat. The probability density of the magnetic energy release in reconnections has a power-law form with the slope -3 , consistent with the solar corona heating by nanoflares.

  3. HOMOLOGOUS FLUX ROPES OBSERVED BY THE SOLAR DYNAMICS OBSERVATORY ATMOSPHERIC IMAGING ASSEMBLY

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ting; Zhang, Jun, E-mail: liting@nao.cas.cn, E-mail: zjun@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2013-12-01

    We present the first Solar Dynamics Observatory observations of four homologous flux ropes in the active region (AR) 11745 on 2013 May 20-22. The four flux ropes are all above the neutral line of the AR, with endpoints anchoring at the same region, and have a generally similar morphology. The first three flux ropes rose with a velocity of less than 30 km s{sup –1} after their appearance, and subsequently their intensities at 131 Å decreased and the flux ropes became obscure. The fourth flux rope erupted last, with a speed of about 130 km s{sup –1} and formed a coronal mass ejection (CME). The associated filament showed an obvious anti-clockwise twist motion at the initial stage, and the twist was estimated at 4π. This indicates that kink instability possibly triggers the early rise of the fourth flux rope. The activated filament material was spatially within the flux rope and showed consistent evolution in the early stages. Our findings provide new clues for understanding the characteristics of flux ropes. Firstly, multiple flux ropes are successively formed at the same location during an AR evolution process. Secondly, a slow-rise flux rope does not necessarily result in a CME, and a fast-eruption flux rope does result in a CME.

  4. Where is the Open Flux?

    Science.gov (United States)

    Linker, Jon A.; Downs, Cooper; Caplan, Ronald M.; Lionello, Roberto; Mikic, Zoran; Riley, Pete; Henney, Carl John; Arge, Charles; Owens, Matthew

    2017-08-01

    The Sun’s magnetic field has been observed in the photosphere from ground- and space-based observatories for many years. Global maps of the solar magnetic field based on full disk magnetograms (either built up over a solar rotation, or evolved using flux transport models) are commonly used as boundary conditions for coronal and solar wind models. Maps from different observatories typically agree qualitatively but often disagree quantitatively. Estimation of the coronal/solar wind physics can range from potential field source surface (PFSS) models with empirical prescriptions to magnetohydrodynamic (MHD) models with realistic energy transport and sub-grid scale descriptions of heating and acceleration. Two primary observational constraints on the models are (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. We have investigated the July 2010 time period, using PFSS and MHD models computed using several available magnetic maps, coronal hole boundaries detected from STEREO and SDO EUV observations, and estimates of the interplanetary magnetic flux from in situ ACE measurements. We show that for all the model/map combinations, models that agree for (1) underestimate the interplanetary magnetic flux, or, conversely, for models to match (2), the modeled open field regions are larger than observed coronal holes. Alternatively, we estimate the open magnetic flux entirely from solar observations by combining detected coronal hole boundaries with observatory synoptic magnetic maps, and show that this method also underestimates the interplanetary magnetic flux. We discuss possible resolutions.Research supported by NASA, AFOSR, and NSF.

  5. Respiratory carbon fluxes in leaves.

    Science.gov (United States)

    Tcherkez, Guillaume; Boex-Fontvieille, Edouard; Mahé, Aline; Hodges, Michael

    2012-06-01

    Leaf respiration is a major metabolic process that drives energy production and growth. Earlier works in this field were focused on the measurement of respiration rates in relation to carbohydrate content, photosynthesis, enzymatic activities or nitrogen content. Recently, several studies have shed light on the mechanisms describing the regulation of respiration in the light and in the dark and on associated metabolic flux patterns. This review will highlight advances made into characterizing respiratory fluxes and provide a discussion of metabolic respiration dynamics in relation to important biological functions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Flux decline in ultrafiltration processes

    NARCIS (Netherlands)

    van den Berg, G.B.; Smolders, C.A.

    1990-01-01

    When a membrane filtration process such as ultrafiltration is used a flux- and yield-decline can be observed. The causes are i) concentration polarization (i.e. accumulation of retained solutes, reversibly and immediately occurring) and ii) fouling phenomena such as adsorption, pore-blocking and

  7. 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.

  8. Simple models with ALICE fluxes

    CERN Document Server

    Striet, J

    2000-01-01

    We introduce two simple models which feature an Alice electrodynamics phase. In a well defined sense the Alice flux solutions we obtain in these models obey first order equations similar to those of the Nielsen-Olesen fluxtube in the abelian higgs model in the Bogomol'nyi limit. Some numerical solutions are presented as well.

  9. High Flux Metallic Membranes for Hydrogen Recovery and Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Buxbaum, Robert

    2010-06-30

    We made and tested over 250 new alloys for use as lower cost, higher flux hydrogen extraction membrane materials. Most of these were intermetallic, or contained significant intermetallic content, particularly based on B2 alloy compositions with at least one refractory component; B2 intermetallics resemble BCC alloys, in structure, but the atoms have relatively fixed positions, with one atom at the corners of the cube, the other at the centers. The target materals we were looking for would contain little or no expensive elements, no strongly toxic or radioactive elements, would have high flux to hydrogen, while being fabricable, brazable, and relatively immune to hydrogen embrittlement and corrosion in operation. The best combination of properties of the membrane materials we developed was, in my opinion, a Pd-coated membrane consisting of V -9 atomic % Pd. This material was relatively cheap, had 5 times the flux of Pd under the same pressure differential, was reasonably easy to fabricate and braze, and not bad in terms of embrittlement. Based on all these factors we project, about 1/3 the cost of Pd, on an area basis for a membrane designed to last 20 years, or 1/15 the cost on a flux basis. Alternatives to this membrane replaced significant fractions of the Pd with Ni and or Co. The cost for these membranes was lower, but so was the flux. We produced successful brazed products from the membrane materials, and made them into flat sheets. We tested, unsuccessfully, several means of fabricating thematerials into tubes, and eventually built a membrane reactor using a new, flat-plate design: a disc and doughnut arrangement, a design that seems well- suited to clean hydrogen production from coal. The membranes and reactor were tested successfully at Western Research. A larger equipment company (Chart Industries) produced similar results using a different flat-plate reactor design. Cost projections of the membrane are shown to be attractive.

  10. 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.)

  11. 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

  12. Neutrino Flux Prediction for the NuMI Beamline

    Energy Technology Data Exchange (ETDEWEB)

    Aliaga Soplin, Leonidas [William-Mary Coll.

    2016-01-01

    The determination of the neutrino flux in any conventional neutrino beam presents a challenge for the current and future short and long baseline neutrino experiments. The uncertainties associated with the production and attenuation of the hadrons in the beamline materials along with those associated with the beam optics have a big effect in the flux spectrum knowledge. For experiments like MINERvA, understanding the flux is crucial since it enters directly into every neutrino-nucleus cross-sections measurements. The foundation of this work is predicting the neutrino flux at MINERvA using dedicated measurements of hadron production in hadron-nucleus collisions and incorporating in-situ MINERvA data that can provide additional constraints. This work also includes the prospect for predicting the flux at other detectors like the NOvA Near detector. The procedure and conclusions of this thesis will have a big impact on future hadron production experiments and on determining the fl ux for the upcoming DUNE experiment.

  13. Dimensional analysis of membrane distillation flux through fibrous membranes

    Science.gov (United States)

    Mauter, Meagan

    We developed a dimensional-analysis-based empirical modeling method for membrane distillation (MD) flux that is adaptable for novel membrane structures. The method makes fewer simplifying assumptions about membrane pore geometry than existing theoretical (i.e. mechanistic) models, and allows selection of simple, easily-measureable membrane characteristics as structural parameters. Furthermore, the model does not require estimation of membrane surface temperatures; it accounts for convective heat transfer to the membrane surface without iterative fitting of mass and heat transfer equations. The Buckingham-Pi dimensional analysis method is tested for direct contact membrane distillation (DCMD) using non-woven/fibrous structures as the model membrane material. Twelve easily-measured variables to describe DCMD operating conditions, fluid properties, membrane structures, and flux were identified and combined into eight dimensionless parameters. These parameters were regressed using experimentally-collected data for multiple electrospun membrane types and DCMD system conditions, achieving R2 values >95%. We found that vapor flux through isotropic fibrous membranes can be estimated using only membrane thickness, solid fraction, and fiber diameter as structural parameters. Buckingham-Pi model DCMD flux predictions compare favorably with previously-developed empirical and theoretical models, and suggest this simple yet theoretically-grounded empirical modeling method can be used practically for predicting MD vapor flux from membrane structural parameters.

  14. Stringent neutrino flux constraints on antiquark nugget dark matter

    Science.gov (United States)

    Gorham, P. W.; Rotter, B. J.

    2017-05-01

    Strongly interacting matter in the form of nuggets of nuclear-density material is not currently excluded as a dark matter candidate in the ten gram to hundreds of kilogram mass range. A recent variation on quark nugget dark matter models postulates that a first-order imbalance between matter and antimatter at the quark-gluon phase transition in the early Universe could lead to most of the dark matter bound into heavy (baryon number B ˜1 025) antiquark nuggets in the current epoch, explaining both the dark matter preponderance and the matter-antimatter asymmetry. Interactions of these massive objects with normal matter in the Earth and Sun lead to annihilation and an associated neutrino flux in the ˜30 MeV range. We calculate these fluxes for antiquark nuggets of sufficient flux to account for the dark matter and find that current neutrino flux limits from Super-Kamiokande (SuperK) exclude these objects as major dark matter candidates at a high confidence level. Antiquark nuggets in the previously allowed mass range cannot account for more than ˜15 % of the dark matter flux.

  15. Flavour mixings in flux compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Buchmuller, Wilfried; Schweizer, Julian

    2017-01-15

    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{sup 2}=Z{sub 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.

  16. Constrained Allocation Flux Balance Analysis

    CERN Document Server

    Mori, Matteo; Martin, Olivier C; De Martino, Andrea; Marinari, Enzo

    2016-01-01

    New experimental results on bacterial growth inspire a novel top-down approach to study cell metabolism, combining mass balance and proteomic constraints to extend and complement Flux Balance Analysis. We introduce here Constrained Allocation Flux Balance Analysis, CAFBA, in which the biosynthetic costs associated to growth are accounted for in an effective way through a single additional genome-wide constraint. Its roots lie in the experimentally observed pattern of proteome allocation for metabolic functions, allowing to bridge regulation and metabolism in a transparent way under the principle of growth-rate maximization. We provide a simple method to solve CAFBA efficiently and propose an "ensemble averaging" procedure to account for unknown protein costs. Applying this approach to modeling E. coli metabolism, we find that, as the growth rate increases, CAFBA solutions cross over from respiratory, growth-yield maximizing states (preferred at slow growth) to fermentative states with carbon overflow (preferr...

  17. Structural Control of Metabolic Flux

    Science.gov (United States)

    Sajitz-Hermstein, Max; Nikoloski, Zoran

    2013-01-01

    Organisms have to continuously adapt to changing environmental conditions or undergo developmental transitions. To meet the accompanying change in metabolic demands, the molecular mechanisms of adaptation involve concerted interactions which ultimately induce a modification of the metabolic state, which is characterized by reaction fluxes and metabolite concentrations. These state transitions are the effect of simultaneously manipulating fluxes through several reactions. While metabolic control analysis has provided a powerful framework for elucidating the principles governing this orchestrated action to understand metabolic control, its applications are restricted by the limited availability of kinetic information. Here, we introduce structural metabolic control as a framework to examine individual reactions' potential to control metabolic functions, such as biomass production, based on structural modeling. The capability to carry out a metabolic function is determined using flux balance analysis (FBA). We examine structural metabolic control on the example of the central carbon metabolism of Escherichia coli by the recently introduced framework of functional centrality (FC). This framework is based on the Shapley value from cooperative game theory and FBA, and we demonstrate its superior ability to assign “share of control” to individual reactions with respect to metabolic functions and environmental conditions. A comparative analysis of various scenarios illustrates the usefulness of FC and its relations to other structural approaches pertaining to metabolic control. We propose a Monte Carlo algorithm to estimate FCs for large networks, based on the enumeration of elementary flux modes. We further give detailed biological interpretation of FCs for production of lactate and ATP under various respiratory conditions. PMID:24367246

  18. Characterisation of Redlen high-flux CdZnTe

    Science.gov (United States)

    Thomas, B.; Veale, M. C.; Wilson, M. D.; Seller, P.; Schneider, A.; Iniewski, K.

    2017-12-01

    CdZnTe is a promising material for the current generation of free electron laser light sources and future laser-driven γ-ray sources which require detectors capable of high flux imaging at X-ray and γ-ray energies (> 10 keV) . However, at high fluxes CdZnTe has been shown to polarise due to hole trapping, leading to poor performance. Novel Redlen CdZnTe material with improved hole transport properties has been designed for high flux applications. Small pixel CdZnTe detectors were fabricated by Redlen Technologies and flip-chip bonded to PIXIE ASICs. An XIA Digital Gamma Finder PIXIE-16 system was used to digitise each of the nine analogue signals with a timing resolution of 10 ns. Pulse shape analysis was used to extract the rise times and amplitude of signals. These were measured as a function of applied bias voltage and used to calculate the mobility (μ) and mobility-lifetime (μτ) of electrons and holes in the material for three identical detectors. The measured values of the transport properties of electrons in the high-flux-capable material was lower than previously reported for Redlen CdZnTe material (μeτe ~ 1 × 10‑3 cm2V‑1 and μe ~ 1000 cm2V‑1s‑1) while the hole transport properties were found to have improved (μhτh ~ 3 × 10‑4 cm2V‑1 and μh ~ 100 cm2V‑1s‑1).

  19. Sediment flux and the Anthropocene.

    Science.gov (United States)

    Syvitski, James P M; Kettner, Albert

    2011-03-13

    Data and computer simulations are reviewed to help better define the timing and magnitude of human influence on sediment flux--the Anthropocene epoch. Impacts on the Earth surface processes are not spatially or temporally homogeneous. Human influences on this sediment flux have a secondary effect on floodplain and delta-plain functions and sediment dispersal into the coastal ocean. Human impact on sediment production began 3000 years ago but accelerated more widely 1000 years ago. By the sixteenth century, societies were already engineering their environment. Early twentieth century mechanization has led to global signals of increased sediment flux in most large rivers. By the 1950s, this sediment disturbance signal reversed for many rivers owing to the proliferation of dams, and sediment load reduction below pristine conditions is the dominant signal today. A delta subsidence signal began in the 1930s and is now a dominant signal in terms of sea level for many coastal environments, overwhelming even the global warming imprint on sea level. Humans have engineered how most water and sediment are discharged into the coastal ocean. Hyperpycnal flow events have become more common for some rivers, and less common for other rivers. Bottom trawling is now widespread, suggesting that even continental shelves have received a significant but as yet quantified Anthropocene impact. The Anthropocene attains the level of a geological climate event, such as that seen in the transition between the Pleistocene and the Holocene.

  20. 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.

  1. production of manual arc welding electrodes with local raw materials

    African Journals Online (AJOL)

    CHUKSSUCCESS 4 LOVE

    ABSTRACT. Manual arc welding using flux coated electrodes is carried out by producing an electric arc between the base metal and a flux covered metal electrode with electric current that depends on the type of electrode, material, welding position and the desired strength. The composition of flux coated electrodes is ...

  2. 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.

  3. Analytical Modeling of a Double-Sided Flux Concentrating E-Core Transverse Flux Machine with Pole Windings

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hasan, Iftekhar [University of Akron; Husain, Tausif [University of Akron; Sozer, Yilmaz [University of Akron; Husain, Iqbal [North Carolina State University

    2017-08-08

    In this paper, a nonlinear analytical model based on the Magnetic Equivalent Circuit (MEC) method is developed for a double-sided E-Core Transverse Flux Machine (TFM). The proposed TFM has a cylindrical rotor, sandwiched between E-core stators on both sides. Ferrite magnets are used in the rotor with flux concentrating design to attain high airgap flux density, better magnet utilization, and higher torque density. The MEC model was developed using a series-parallel combination of flux tubes to estimate the reluctance network for different parts of the machine including air gaps, permanent magnets, and the stator and rotor ferromagnetic materials, in a two-dimensional (2-D) frame. An iterative Gauss-Siedel method is integrated with the MEC model to capture the effects of magnetic saturation. A single phase, 1 kW, 400 rpm E-Core TFM is analytically modeled and its results for flux linkage, no-load EMF, and generated torque, are verified with Finite Element Analysis (FEA). The analytical model significantly reduces the computation time while estimating results with less than 10 percent error.

  4. High-flux solar photon processes

    Energy Technology Data Exchange (ETDEWEB)

    Lorents, D C; Narang, S; Huestis, D C; Mooney, J L; Mill, T; Song, H K; Ventura, S [SRI International, Menlo Park, CA (United States)

    1992-06-01

    This study was commissioned by the National Renewable Energy Laboratory (NREL) for the purpose of identifying high-flux photoprocesses that would lead to beneficial national and commercial applications. The specific focus on high-flux photoprocesses is based on the recent development by NREL of solar concentrator technology capable of delivering record flux levels. We examined photolytic and photocatalytic chemical processes as well as photothermal processes in the search for processes where concentrated solar flux would offer a unique advantage. 37 refs.

  5. Calibration of soil heat flux sensors.

    NARCIS (Netherlands)

    Loon, van W.K.P.; Bastings, H.M.H.; Moors, E.J.

    1998-01-01

    Soil heat flux is difficult to measure accurately and soil heat flux plates are difficult to calibrate. In this research the reference heat flux was calculated from the temperature gradient and independent thermal conductivity measurements. Reference conductivities, as measured by the non-steady

  6. 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

  7. Metabolic Flux Analysis of Mammalian Cells

    NARCIS (Netherlands)

    Martens, D.E.

    2006-01-01

    Metabolic flux analysis has become a standard tool for analyzing metabolism and optimizing bioprocesses. Metabolic flux analysis makes use of a metabolic reaction network in combination with extra-cellular measurements and mass balancing to calculate flux distributions in metabolism. It is a useful

  8. Apparatus for measuring a flux of neutrons

    Science.gov (United States)

    Stringer, James L.

    1977-01-01

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

  9. Surface Catalysis and Oxidation on Stagnation Point Heat Flux Measurements in High Enthalpy Arc Jets

    Science.gov (United States)

    Nawaz, Anuscheh; Driver, David M.; Terrazas-Salinas

    2013-01-01

    Heat flux sensors are routinely used in arc jet facilities to determine heat transfer rates from plasma plume. The goal of this study is to assess the impact of surface composition changes on these heat flux sensors. Surface compositions can change due to oxidation and material deposition from the arc jet. Systematic surface analyses of the sensors were conducted before and after exposure to plasma. Currently copper is commonly used as surface material. Other surface materials were studied including nickel, constantan gold, platinum and silicon dioxide. The surfaces were exposed to plasma between 0.3 seconds and 3 seconds. Surface changes due to oxidation as well as copper deposition from the arc jets were observed. Results from changes in measured heat flux as a function of surface catalycity is given, along with a first assessment of enthalpy for these measurements. The use of cupric oxide is recommended for future heat flux measurements, due to its consistent surface composition arc jets.

  10. Heat transfer and critical heat flux in a spiral flow in an asymmetrical heated tube; Transfert thermique et flux critique dans un ecoulement helicoidal en tube chauffe asymetriquement

    Energy Technology Data Exchange (ETDEWEB)

    Boscary, J. [CEA Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Direction des Sciences de la Matiere]|[Association Euratom-CEA, Centre d`Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    1997-03-01

    The design of plasma facing components is crucial for plasma performance in next fusion reactors. These elements will be submitted to very high heat flux. They will be actively water-cooled by swirl tubes in the subcooled boiling regime. High heat flux experiments were conducted in order to analyse the heat transfer and to evaluate the critical heat flux. Water-cooled mock-ups were one-side heated by an electron beam gun for different thermal-hydraulic conditions. The critical heat flux was detected by an original method based on the isotherm modification on the heated surface. The wall heat transfer law including forced convection and subcooled boiling regimes was established. Numerical calculations of the material heat transfer conduction allowed the non-homogeneous distribution of the wall temperature and of the wall heat flux to be evaluated. The critical heat flux value was defined as the wall maximum heat flux. A critical heat flux model based on the liquid sublayer dryout under a vapor blanket was established. A good agreement with test results was found. (author) 197 refs.

  11. Heat transfer and critical heat flux in a asymmetrically heated tube helicoidal flow; Transfert thermique et flux critique dans un ecoulement helicoidal en tube chauffe asymetriquement

    Energy Technology Data Exchange (ETDEWEB)

    Boscary, J.

    1995-10-01

    The design of plasma facing components is crucial for plasma performance in next fusion reactors. These elements will be submitted to very high heat flux. They will be actively water-cooled by swirl tubes in the subcooled boiling regime. High heat flux experiments were conducted in order to analyse the heat transfer and to evaluate the critical heat flux. Water-cooled mock-ups were one-side heated by an electron beam gun for different thermal-hydraulic conditions. The critical heat flux was detected by an original method based on the isotherm modification on the heated surface. The wall heat transfer law including forced convection and subcooled boiling regimes was established. Numerical calculations of the material heat transfer conduction allowed the non-homogeneous distribution of the wall temperature and of the wall heat flux to be evaluated. The critical heat flux value was defined as the wall maximum heat flux. A critical heat flux model based on the liquid sublayer dryout under a vapor blanket was established. A good agreement with test results was found. (author). 198 refs., 126 figs., 21 tabs.

  12. A closed-chamber method to measure greenhouse gas fluxes from dry aquatic sediments

    Science.gov (United States)

    Lesmeister, Lukas; Koschorreck, Matthias

    2017-06-01

    Recent research indicates that greenhouse gas (GHG) emissions from dry aquatic sediments are a relevant process in the freshwater carbon cycle. However, fluxes are difficult to measure because of the often rocky substrate and the dynamic nature of the habitat. Here we tested the performance of different materials to seal a closed chamber to stony ground both in laboratory and field experiments. Using on-site material consistently resulted in elevated fluxes. The artefact was caused both by outgassing of the material and production of gas. The magnitude of the artefact was site dependent - the measured CO2 flux increased between 10 and 208 %. Errors due to incomplete sealing proved to be more severe than errors due to non-inert sealing material.Pottery clay as sealing material provided a tight seal between the chamber and the ground and no production of gases was detected. With this approach it is possible to get reliable gas fluxes from hard-substrate sites without using a permanent collar. Our test experiments confirmed that CO2 fluxes from dry aquatic sediments are similar to CO2 fluxes from terrestrial soils.

  13. A closed-chamber method to measure greenhouse gas fluxes from dry aquatic sediments

    Directory of Open Access Journals (Sweden)

    L. Lesmeister

    2017-06-01

    Full Text Available Recent research indicates that greenhouse gas (GHG emissions from dry aquatic sediments are a relevant process in the freshwater carbon cycle. However, fluxes are difficult to measure because of the often rocky substrate and the dynamic nature of the habitat. Here we tested the performance of different materials to seal a closed chamber to stony ground both in laboratory and field experiments. Using on-site material consistently resulted in elevated fluxes. The artefact was caused both by outgassing of the material and production of gas. The magnitude of the artefact was site dependent – the measured CO2 flux increased between 10 and 208 %. Errors due to incomplete sealing proved to be more severe than errors due to non-inert sealing material.Pottery clay as sealing material provided a tight seal between the chamber and the ground and no production of gases was detected. With this approach it is possible to get reliable gas fluxes from hard-substrate sites without using a permanent collar. Our test experiments confirmed that CO2 fluxes from dry aquatic sediments are similar to CO2 fluxes from terrestrial soils.

  14. Geometrical correction factors for heat flux meters

    Science.gov (United States)

    Baumeister, K. J.; Papell, S. S.

    1974-01-01

    General formulas are derived for determining gage averaging errors of strip-type heat flux meters used in the measurement of one-dimensional heat flux distributions. The local averaging error e(x) is defined as the difference between the measured value of the heat flux and the local value which occurs at the center of the gage. In terms of e(x), a correction procedure is presented which allows a better estimate for the true value of the local heat flux. For many practical problems, it is possible to use relatively large gages to obtain acceptable heat flux measurements.

  15. Flux limiters and Eddington factors

    Energy Technology Data Exchange (ETDEWEB)

    Pomraning, G.C.

    1982-01-01

    In this paper a closure scheme for the first two angular moments of the time-dependent equation of transfer is presented, either via an Eddington factor which leads to a telegrapher's description, or via a Fick's law which leads to a diffusion description. Points discussed include boundary conditions (both an extension of the classic Marshak-Milne condition and those arising from a boundary layer analysis), the flux limiting feature of the diffusion approximation, and the reduction of the theory to asymptotic diffusion theory in the steady state limit.

  16. Methane Fluxes from Subtropical Wetlands

    Science.gov (United States)

    DeLucia, N.; Gomez-Casanovas, N.; Bernacchi, C.

    2013-12-01

    It is well documented that green house gas concentrations have risen at unequivocal rates since the industrial revolution but the disparity between anthropogenic sources and natural sources is uncertain. Wetlands are one example of a natural ecosystem that can be a substantial source or sink for methane (CH4) depending on climate conditions. Due to strict anaerobic conditions required for CH4-generating microorganisms, natural wetlands are one of the main sources for biogenic CH4. Although wetlands occupy less than 5% of total land surface area, they contribute approximately 20% of total CH4 emissions to the atmosphere. The processes regulating CH4 emissions are sensitive to land use and management practices of areas surrounding wetlands. Variation in adjacent vegetation or grazing intensity by livestock can, for example, alter CH4 fluxes from wetland soils by altering nutrient balance, carbon inputs and hydrology. Therefore, understanding how these changes will affect wetland source strength is essential to understand the impact of wetland management practices on the global climate system. In this study we quantify wetland methane fluxes from subtropical wetlands on a working cattle ranch in central Florida near Okeechobee Lake (27o10'52.04'N, 81o21'8.56'W). To determine differences in CH4 fluxes associated with land use and management, a replicated (n = 4) full factorial experiment was designed for wetlands where the surrounding vegetation was (1) grazed or un-grazed and (2) composed of native vegetation or improved pasture. Net exchange of CH4 and CO2 between the land surface and the atmosphere were sampled with a LICOR Li-7700 open path CH4 analyzer and Li-7500A open path CO2/H20 analyzer mounted in a 1-m3 static gas-exchange chamber. Our results showed and verified that CH4 emissions from subtropical wetlands were larger when high soil moisture was coupled with high temperatures. The presence of cattle only amplified these results. These results help quantify

  17. Chemistry and Properties of Complex Intermetallics from Metallic Fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Kanatzidis, Mercouri G. [Northwestern Univ., Evanston, IL (United States)

    2015-03-28

    This project investigated the reaction chemistry and synthesis of new intermetallic materials with complex compositions and structures using metallic fluxes as solvents. It was found that the metallic fluxes offer several key advantages in facilitating the formation and crystal growth of new materials. The fluxes mostly explored were liquid aluminum, gallium and indium. The main purpose of this project was to exploit the potential of metallic fluxes as high temperature solvent for materials discovery in the broad class of intermetallics. This work opened new paths to compound formation. We discovered many new Si (or Ge)-based compounds with novel structures, bonding and physicochemical properties. We created new insights about the reaction chemistry that is responsible for stabilizing the new materials. We also studied the structural and compositional relationships to understand their properties. We investigated the use of Group-13 metals Al, Ga and In as solvents and have generated a wide variety of new results including several new ternary and quaternary materials with fascinating structures and properties as well as new insights as to how these systems are stabilized in the fluxes. The project focused on reactions of metals from the rare earth element family in combination with transition metals with Si and Ge. For example molten gallium has serves both as a reactive and non-reactive solvent in the preparation and crystallization of intermetallics in the system RE/M/Ga/Ge(Si). Molten indium behaves similarly in that it too is an excellent reaction medium, but it gives compounds that are different from those obtained from gallium. Some of the new phase identified in the aluminide class are complex phases and may be present in many advanced Al-matrix alloys. Such phases play a key role in determining (either beneficially or detrimentally) the mechanical properties of advanced Al-matrix alloys. This project enhanced our basic knowledge of the solid state chemistry

  18. Flux of Millimetric Space Debris

    Science.gov (United States)

    Goldstein, R. M.; Goldstein, S. J., Jr.

    1995-01-01

    In 21.4 hr of zenith radar observations on 4 days at 8510 MHz, we found 831 particles with altitudes between 177 and 1662 km. From the duration of the echoes and the angular size (0.030 deg) of the antenna beam 157 particles were identified as passing through the side lobes and not through the main beam. Our analysis is based on the 674 particles that did not broaden the beam. On the assumptions that these particles went through the main beam, their radar cross sections vary between 0.02 and 260 sq mm , and their radial velocities vary between +/- 700 m/s. If they are conducting spheres, their diameters lie between 2 and 18 mm. If not, they must be larger. The flux of these particles, that is the number per sq km day, was determined in 100 km intervals. The maximum flux, 3.3 particles per sq km day, occurs at 950 km altitude. The small and large particles are not well mixed. The largest particles occur beyond 1000 km and middle-sized particles are missing below 300 km. If the earth's atmosphere caused the smallest particles to lose energy from initial orbits identical to those of the large particles, the orbits would have lower eccentricity at low altitudes. We find a larger eccentricity for the inner particles, and conclude that two or more populations are present.

  19. DWSB in heterotic flux compactifications

    CERN Document Server

    Held, Johannes; Marchesano, Fernando; Martucci, Luca

    2010-01-01

    We address the construction of non-supersymmetric vacua in heterotic compactifications with intrinsic torsion and background fluxes. In particular, we implement the approach of domain-wall supersymmetry breaking (DWSB) previously developed in the context of type II flux compactifications. This approach is based on considering backgrounds where probe NS5-branes wrapping internal three-cycles and showing up as four-dimensional domain-walls do not develop a BPS bound, while all the other BPS bounds characterizing the N=1 supersymmetric compactifications are preserved at tree-level. Via a scalar potential analysis we provide the conditions for these backgrounds to solve the ten-dimensional equations of motion including order \\alpha' corrections. We also consider backgrounds where some of the NS5-domain-walls develop a BPS bound, show their relation to no-scale SUSY-breaking vacua and construct explicit examples via elliptic fibrations. Finally, we consider backgrounds with a non-trivial gaugino condensate and dis...

  20. High-flux solar photon processes: Opportunities for applications

    Energy Technology Data Exchange (ETDEWEB)

    Steinfeld, J.I.; Coy, S.L.; Herzog, H.; Shorter, J.A.; Schlamp, M.; Tester, J.W.; Peters, W.A. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1992-06-01

    The overall goal of this study was to identify new high-flux solar photon (HFSP) processes that show promise of being feasible and in the national interest. Electric power generation and hazardous waste destruction were excluded from this study at sponsor request. Our overall conclusion is that there is promise for new applications of concentrated solar photons, especially in certain aspects of materials processing and premium materials synthesis. Evaluation of the full potential of these and other possible applications, including opportunities for commercialization, requires further research and testing. 100 refs.

  1. How the Saturnian Magnetosphere Conserves Magnetic Flux

    Science.gov (United States)

    Powell, R. L.; Wei, H.; Russell, C. T.; Arridge, C. S.; Dougherty, M. K.

    2012-12-01

    The magnetospheric dynamics at Saturn are driven by the centrifugal force of near co-rotating water group ions released at a rate of hundreds of kilograms per second by Saturn's moon Enceladus. The plasma is accelerated up to co-rotation speed by the magnetospheric magnetic field coupled to the Saturnian ionosphere. The plasma is lost ultimately through the process of magnetic reconnection in the tail. Conservation of magnetic flux requires that plasma-depleted, "empty" flux tubes return magnetic flux to the inner magnetosphere. After completion of the initial inrush of the reconnected and largely emptied flux tubes inward of the reconnection point, the flux tubes face the outflowing plasma and must move inward against the flow. Observations of such flux tubes have been identified in the eight years of Cassini magnetometer data. The occurrence of these tubes is observed at all local times indicating slow inward transport of the tubes relative to the co-rotation speed. Depleted flux tubes observed in the equatorial region appear as an enhancement in the magnitude of the magnetic field, whereas the same flux tubes observed at higher latitudes appear as decreased field strength. The difference in appearance of the low latitude and the high latitude tubes is due to the plasma environment just outside the tube. Warm low-density plasma fills the inside of the flux tube at all latitudes. This flux tube thus will expand in the less dense regions away from the magnetic equator and will be observed as a decrease in the magnitude of the magnetic field from the background. These flux tubes near the equator, where the plasma density outside of the flux tube is much greater, will be observed as an enhancement in the magnitude of the magnetic field. Cassini magnetometer and CAPS data are examined to understand the properties of these flux tubes and their radial and latitudinal evolution throughout the Saturnian magnetospheric environment.

  2. Partitioning evapotranspiration fluxes using atmometer

    Science.gov (United States)

    Orsag, Matej; Fischer, Milan; Trnka, Miroslav; Kucera, Jiri; Zalud, Zdenek

    2013-04-01

    This effort is aimed to derive a simple tool for separating soil evaporation and transpiration from evapotranspiration, measured by Bowen ration energy balance method (BREB) in short rotation coppice (SRC). The main idea is to utilize daily data of actual evapotranspiration (ETa) measured above bare soil (spring 2010 - first year following harvest), reference evapotranspiration (ETo) measured by atmometer ETgage and precipitation data, in order to create an algorithm for estimation evaporation from bare soil. This approach is based on the following assumption: evaporation of wetted bare soil same as the ETo from atmometer is assumed to be identical in days with rain. In first and further days with no rain (and e.g. high evaporative demand) the easily evaporable soil water depletes and ETa so as crop coefficient of bare soil (Kcb) decreases in a way similar to decreasing power function. The algorithm represents a parameterized function of daily cumulated ETo (ETc) measured by atmometer in days elapsed from last rain event (Kcb = a*ETc^b). After each rain event the accumulation of ETo starts again till next rain event (e. g. only days with no rain are cumulated). The function provides decreasing Kcb for each day without rain. The bare soil evaporation can be estimated when the atmometer-recorded value is multiplied by Kcb for particular day without rain. In days with rain Kcb is assumed to be back at 1. This method was successfully tested for estimating evaporation from bare soil under closed canopy of poplar-based SRC. When subtracting the estimated soil evaporation from total ETa flux, measured above the canopy using BREB method, it is possible to obtain transpiration flux of the canopy. There is also possibility to test this approach on the contrary - subtracting transpiration derived from sap-flow measurement from total ETa flux is possible to get soil evaporation as well. Acknowledgements: The present experiment is made within the frame of project Inter

  3. Localized fast neutron flux enhancement for damage experiments in a research reactor; Accroissement local du flux rapide pour des experiences de dommages dans un reacteur de recherche

    Energy Technology Data Exchange (ETDEWEB)

    Malouch, F

    2003-06-01

    In irradiation experiments on materials in the core of the Osiris reactor (CEA-Saclay) we seek to increase damage in irradiated samples and to reduce the duration of their stay in the core. Damage is essentially caused by fast neutrons (E {>=} 1 MeV); we have therefore pursued the possibility of a localized increase of their level in an irradiation experiment by using a flux converter device made up of fissile material arranged according to a suitable geometry that allows the converter to receive experiments. We have studied several parameters that are influential in the increase of fast neutron flux within the converter. We have also considered the problem of the converter's cooling in the core and its effect on the operation of the reactor. We have carried out a specific neutron calculation scheme based on the modular 2D-transport code APOLLO2 using a two-level transport method. Experimental validation of the flux calculation scheme was carried out in the ISIS reactor, the mock-up of OSIRIS, by optimizing the loading of fuel elements in the core. The experimental results show that the neutron calculation scheme computes the fluxes in close agreement with the measurements especially the fast flux. This study allows us to master the essential physical parameters needed for the design of a flux converter in an MTR reactor. (author)

  4. Design and analysis of a 3D-flux flux-switching permanent magnet machine with SMC cores and ferrite magnets

    Science.gov (United States)

    Liu, Chengcheng; Wang, Youhua; Lei, Gang; Guo, Youguang; Zhu, Jianguo

    2017-05-01

    Since permanent magnets (PM) are stacked between the adjacent stator teeth and there are no windings or PMs on the rotor, flux-switching permanent magnet machine (FSPMM) owns the merits of good flux concentrating and robust rotor structure. Compared with the traditional PM machines, FSPMM can provide higher torque density and better thermal dissipation ability. Combined with the soft magnetic composite (SMC) material and ferrite magnets, this paper proposes a new 3D-flux FSPMM (3DFFSPMM). The topology and operation principle are introduced. It can be found that the designed new 3DFFSPMM has many merits over than the traditional FSPMM for it can utilize the advantages of SMC material. Moreover, the PM flux of this new motor can be regulated by using the mechanical method. 3D finite element method (FEM) is used to calculate the magnetic field and parameters of the motor, such as flux density, inductance, PM flux linkage and efficiency map. The demagnetization analysis of the ferrite magnet is also addressed to ensure the safety operation of the proposed motor.

  5. Flux Recovery of a Forward Osmosis Membrane After a Fouling Process

    Science.gov (United States)

    Romero-Mangado, Jaione; Parodi, Jurek; Gamboa-Vazquez, Sonia; Stefanson, Ofir; Diaz-Cartagena, Diana C.; Flynn, Michael

    2016-01-01

    Wastewater treatment through forward osmosis (FO) membranes is a process that has been evaluated in the past years as an innovative technology for the Next Generation Life Support Systems. FO technologies are cost effective, and require very low energy consumption, but are subject to membrane fouling. Membrane fouling occurs when unwanted materials accumulate on the active side of the membrane during the wastewater treatment process, which leads to a decrease in membrane flux rate. The aim of this study is to identify the materials that cause flux rate reduction due to membrane fouling, as well as to evaluate the flux rate recovery after membrane treatment using commercially available antifoulants. Fourier Transform Infrared (FTIR) spectrometry results identified possible compounds that cause membrane fouling and FO testing results demonstrated flux rate recovery after membrane treatment using antifoulants.

  6. Evaluation of fluxing agents effect on desulphurization in secondary metallurgy under plant conditions

    Directory of Open Access Journals (Sweden)

    L. Socha

    2013-10-01

    Full Text Available In the steel industry, a number of fluxing agents based on Al2O3 is commonly used. They are produced in different forms. This paper deals with plant results and experiences with the usage of briquetted and sintered fluxing agents for slags based on Al2O3. Proper plant heats were processed under conditions of steel plant Vítkovice heavy machinery a.s. during production of steel S34MnV by specific technology: EAF→LF→VCD. During experiments, the basic parameters influencing the steel desulphurization were monitored. Obtained results allow us to make a basic comparison of briquetted fluxing agents produced from secondary raw materials and of sintered fluxing agents, which are produced from pure raw materials.

  7. Chaos in Magnetic Flux Ropes

    Science.gov (United States)

    Gekelman, Walter; DeHaas, T.; Van Compernolle, B.; Vincena, S.

    2013-07-01

    Magnetic Flux Ropes Immersed in a uniform magnetoplasma are observed to twist about themselves, writhe about each other and rotate about a central axis. They are kink unstable and smash into one another as they move. Each collision results in magnetic field line generation and the generation of a quasi-seperatrix layer. Three dimensional magnetic field lines are computed by conditionally averaging the data using correlation techniques. When the currents associated with the ropes are large,this is possible for only a number of rotation cycles as the field line motion becomes chaotic. The permutation entropy1 can be calculated from the the time series of the magnetic field data (this is also done with flows) and used to calculate the positions of the data on a Jensen Shannon complexity map2. The power spectra of much of the magnetic and flow data is exponential and Lorentzian structures in the time domain are embedded in them. The location of data on this map indicates if the magnetic fields are stochastic, or fall into regions of minimal or maximal complexity. The complexity is a function of space and time. The complexity map, and analysis will be explained in the course of the talk. Other types of chaotic dynamical models such as the Lorentz or Gissinger process also fall on the map and can give a clue to the nature of the flux rope turbulence. The ropes fall in the region of the C-H plane where chaotic systems lie. 1 C. Bandt, B. Pompe, Phys. Rev. Lett., 88,174102 (2007) 2 O. Russo et al., Phys. Rev. Lett., 99, 154102 (2007), J. Maggs, G.Morales, “Permutation Entropy analysis of temperature fluctuations from a basic electron heat transport experiment”,submitted PPCF (2013)

  8. Deep-sea fluxes of barium and lithogenic trace elements in the subtropical northeast Atlantic

    Science.gov (United States)

    Stern, Judith; Dellwig, Olaf; Waniek, Joanna J.

    2017-04-01

    Total particle flux, Barium and lithogenic trace element fluxes were measured at the mooring Kiel 276 (33°N, 22°W) in the deep-sea of the subtropical Northeast Atlantic. The particulate material was collected between 2002 and 2008 with a sediment trap in 2000 m depth and analyzed with ICP-OES/-MS to determine its geochemical composition. The particle flux is controlled by primary production, lithogenic particle inputs via atmospheric transport and the migration of the Azores Front. We used refractory trace elements (eg. Ti, Zr, and the rare earth elements) to demonstrate the changes in flux and composition of the material due to lithogenic inputs. Shortly after periods of high dust load and enhanced primary production an increase in lithogenic trace element fluxes occurred. Especially the formation of aggregates with biogenic matter seems to have a major impact on the downwards transport of lithogenic particles. The observation of particulate Ba is of great interest since it is known as a proxy for past and present primary production. Ba fluxes ranging between 0.02 mg m-2 d-1 and 1.21 mg m-2 d-1 with biogenic proportions up to 97%. The fluxes of particulate Barium in the water column are mainly attributed to the strength of primary production.

  9. Optimizing laboratory-based radon flux measurements for sediments.

    Science.gov (United States)

    Chanyotha, Supitcha; Kranrod, Chutima; Kritsananuwat, Rawiwan; Lane-Smith, Derek; Burnett, William C

    2016-07-01

    Radon flux via diffusion from sediments and other materials may be determined in the laboratory by circulating air through the sample and a radon detector in a closed loop. However, this approach is complicated by the necessity of having to determine the total air volume in the system and accounting for any small air leaks that can arise if using extended measurement periods. We designed a simple open-loop configuration that includes a measured mass of wet sediment and water inside a gas-tight reaction flask connected to a drying system and a radon-in-air analyzer. Ambient air flows through two charcoal columns before entering the reaction vessel to eliminate incoming radon. After traveling through the reaction flask, the air passes the drier and the radon analyzer and is then vented. After some time, the radon activity will reach a steady state depending upon the airflow rate. With this approach, the radon flux via diffusion is simply the product of the steady-state radon activity (Bq/m(3)) multiplied by the airflow rate (mL/min). We demonstrated that this setup could produce good results for materials that produce relatively high radon fluxes. We also show that a modified closed system approach, including radon removal of the incoming air by charcoal filtration in a bypass, can produce very good results including samples with very low emission rates. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. A Novel Approach to the Design of Axial-Flux Switched-Reluctance Motors

    OpenAIRE

    Lambert, Tim; Biglarbegian, Mohammad; Mahmud, Shohel

    2015-01-01

    This paper presents the design of a new axial-flux switched-reluctance motor (AFSRM) topology for in-wheel drive vehicle applications. The features of the topology include a short flux path and an outer-rotor configuration. The proposed topology also uses a sintered-lamellar soft magnetic composite core material, and permits displacement of the rotor along the suspension axis, which reduces damage to the stator caused by impacts and vibrations. The combination of these features makes this new...

  11. Distribution of thermal neutron flux around a PET cyclotron.

    Science.gov (United States)

    Ogata, Yoshimune; Ishigure, Nobuhito; Mochizuki, Shingo; Ito, Kengo; Hatano, Kentaro; Abe, Junichiro; Miyahara, Hiroshi; Masumoto, Kazuyoshi; Nakamura, Hajime

    2011-05-01

    The number of positron emission tomography (PET) examinations has greatly increased world-wide. Since positron emission nuclides for the PET examinations have short half-lives, they are mainly produced using on-site cyclotrons. During the production of the nuclides, significant quantities of neutrons are generated from the cyclotrons. Neutrons have potential to activate the materials around the cyclotrons and cause exposure to the staff. To investigate quantities and distribution of the thermal neutrons, thermal neutron fluxes were measured around a PET cyclotron in a laboratory associating with a hospital. The cyclotron accelerates protons up to 18 MeV, and the mean particle current is 20 μA. The neutron fluxes were measured during both 18F production and C production. Gold foils and thermoluminescent dosimeter (TLD) badges were used to measure the neutron fluxes. The neutron fluxes in the target box averaged 9.3 × 10(6) cm(-2) s(-1) and 1.7 × 10(6) cm(-2) s(-1) during 18F and 11C production, respectively. Those in the cyclotron room averaged 4.1 × 10(5) cm(-2) s(-1) and 1.2 × 10(5) cm(-2) s(-1), respectively. Those outside the concrete wall shielding were estimated as being equal to or less than ∼3 cm s, which corresponded to 0.1 μSv h(-1) in effective dose. The neutron fluxes outside the concrete shielding were confirmed to be quite low compared to the legal limit.

  12. Proceedings of US/Japan workshop, Q219 on high heat flux components and plasma surface interactions for next fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Ulrickson, M.A.; Stevens, P.L.; Hino, T.; Hirohata, Y. [eds.

    1996-12-01

    This report contains the viewgraphs from the proceedings of US/Japan Workshop on High Heat Flux Components and Plasma Surface Interactions for Next Fusion Devices. Some of the general topics covered by this report are: PFC/PSI in tokamak and helical devices; development of high heat flux components; PSIS and plasma facing materials;tritium; and material damage.

  13. Beginner’s guide to flux crystal growth

    CERN Document Server

    Tachibana, Makoto

    2017-01-01

    This book introduces the principles and techniques of crystal growth by the flux method, which is arguably the most useful way to obtain millimeter- to centimeter-sized single crystals for physical research. As it is possible to find an appropriate solvent (“flux”) for nearly all inorganic materials, the flux method can be applied to the growth of many crystals ranging from transition metal oxides to intermetallic compounds. Both important principles and experimental procedures are described in a clear and accessible manner. Practical advice on various aspects of the experiment, which is not readily available in the literature, will assist the beginning graduate students in setting up the lab and conducting successful crystal growth. The mechanisms of crystal growth at an elementary level are also provided to better understand the techniques and to help in assessing the quality of the crystals. The book also contains many photographs of beautiful crystals with important physical properties of current inte...

  14. Comparison of the high temperature heat flux sensor to traditional heat flux gages under high heat flux conditions.

    Energy Technology Data Exchange (ETDEWEB)

    Blanchat, Thomas K.; Hanks, Charles R.

    2013-04-01

    Four types of heat flux gages (Gardon, Schmidt-Boelter, Directional Flame Temperature, and High Temperature Heat Flux Sensor) were assessed and compared under flux conditions ranging between 100-1000 kW/m2, such as those seen in hydrocarbon fire or propellant fire conditions. Short duration step and pulse boundary conditions were imposed using a six-panel cylindrical array of high-temperature tungsten lamps. Overall, agreement between all gages was acceptable for the pulse tests and also for the step tests. However, repeated tests with the HTHFS with relatively long durations at temperatures approaching 1000ÀC showed a substantial decrease (10-25%) in heat flux subsequent to the initial test, likely due to the mounting technique. New HTHFS gages have been ordered to allow additional tests to determine the cause of the flux reduction.

  15. 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.

  16. CycleFreeFlux: efficient removal of thermodynamically infeasible loops from flux distributions.

    Science.gov (United States)

    Desouki, Abdelmoneim Amer; Jarre, Florian; Gelius-Dietrich, Gabriel; Lercher, Martin J

    2015-07-01

    Constraint-based metabolic modeling methods such as Flux Balance Analysis (FBA) are routinely used to predict metabolic phenotypes, e.g. growth rates, ATP yield or the fitness of gene knockouts. One frequent difficulty of constraint-based solutions is the inclusion of thermodynamically infeasible loops (or internal cycles), which add nonbiological fluxes to the predictions. We propose a simple postprocessing of constraint-based solutions, which removes internal cycles from any given flux distribution [Formula: see text] without disturbing other fluxes not involved in the loops. This new algorithm, termed CycleFreeFlux, works by minimizing the sum of absolute fluxes [Formula: see text] while (i) conserving the exchange fluxes and (ii) using the fluxes of the original solution to bound the new flux distribution. This strategy reduces internal fluxes until at least one reaction of every possible internal cycle is inactive, a necessary and sufficient condition for the thermodynamic feasibility of a flux distribution. If alternative representations of the input flux distribution in terms of elementary flux modes exist that differ in their inclusion of internal cycles, then CycleFreeFlux is biased towards solutions that maintain the direction given by [Formula: see text] and towards solutions with lower total flux [Formula: see text]. Our method requires only one additional linear optimization, making it computationally very efficient compared to alternative strategies. We provide freely available R implementations for the enumeration of thermodynamically infeasible cycles as well as for cycle-free FBA solutions, flux variability calculations and random sampling of solution spaces. lercher@cs.uni-duesseldorf.de. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  17. 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...

  18. Asteroidal and cometary dust flux in the inner solar system

    Science.gov (United States)

    Borin, P.; Cremonese, G.; Marzari, F.; Lucchetti, A.

    2017-09-01

    Context. Meteoroids impacting terrestrial planets at high speed may have different effects. On bodies without atmospheres, such as the Moon and Mercury, they form impact craters and contribute to the gardening process through which the surface material is constantly mixed. The interaction of high-speed meteoroids with the atmosphere of Venus, the Earth, and Mars, may lead to the deposition in the ionosphere of species such as neutral Mg or Fe and their ionized atoms, caused by ablation processes during the entry. Aims: In this work we estimate and compare the flux and impact speeds onto the planets of the inner solar system by numerically integrating the orbital evolution of putative dust particles of asteroidal and cometary origin. Methods: The trajectories of dust particles of different sizes are computed with a numerical code that accounts for the gravitational forces due to all planets, the Poynting-Robertson drag and the solar wind drag. The flux of dust grains on each planet is estimated by calibrating the outcome of our model with the flux on the Earth reported previously. Results: We obtain new estimates of the flux and impact velocities for both asteroidal and cometary dust particles on Venus and Mars. For Venus we find that cometary grains enter the planet atmosphere at higher speeds, possibly contributing to the upper layers, while asteroidal grains would be relevant for the lower layers, possibly leading to a compositional gradient. This effect is also present for Mars, but it is less marked. We also find that analytical predictions, not taking radiative forces into account, of both flux and average impact speed are reliable for Mars but fail for Venus because of the complex dynamical evolution of grains in the inner solar system. Conclusions: Our results on the velocity distributions and fluxes of micrometeoroids on the terrestrial planets can be used to put stringent contraints on models that estimate either the superficial material mixing that is due

  19. Prediction of metabolic fluxes by incorporating genomic context and flux-converging pattern analyses.

    Science.gov (United States)

    Park, Jong Myoung; Kim, Tae Yong; Lee, Sang Yup

    2010-08-17

    Flux balance analysis (FBA) of a genome-scale metabolic model allows calculation of intracellular fluxes by optimizing an objective function, such as maximization of cell growth, under given constraints, and has found numerous applications in the field of systems biology and biotechnology. Due to the underdetermined nature of the system, however, it has limitations such as inaccurate prediction of fluxes and existence of multiple solutions for an optimal objective value. Here, we report a strategy for accurate prediction of metabolic fluxes by FBA combined with systematic and condition-independent constraints that restrict the achievable flux ranges of grouped reactions by genomic context and flux-converging pattern analyses. Analyses of three types of genomic contexts, conserved genomic neighborhood, gene fusion events, and co-occurrence of genes across multiple organisms, were performed to suggest a group of fluxes that are likely on or off simultaneously. The flux ranges of these grouped reactions were constrained by flux-converging pattern analysis. FBA of the Escherichia coli genome-scale metabolic model was carried out under several different genotypic (pykF, zwf, ppc, and sucA mutants) and environmental (altered carbon source) conditions by applying these constraints, which resulted in flux values that were in good agreement with the experimentally measured (13)C-based fluxes. Thus, this strategy will be useful for accurately predicting the intracellular fluxes of large metabolic networks when their experimental determination is difficult.

  20. Theoretical models of flux pinning and flux motion in high-{Tc} superconducting oxides

    Energy Technology Data Exchange (ETDEWEB)

    Welch, D.O.

    1991-12-31

    Various issues involved in the development of phenomenological models of flux pinning and motion in high-{Tc} oxides are discussed. A simplified model is presented for the critical current density and is used to examine the question of whether flux flow results from an instability due to plasticity of the flux-line array or from pin breaking.

  1. 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. Measu...

  2. On flux terms in volume averaging

    NARCIS (Netherlands)

    Chu, S.G.; Prosperetti, Andrea

    2016-01-01

    This note examines the modeling of non-convective fluxes (e.g., stress, heat flux and others) as they appear in the general, unclosed form of the volume-averaged equations of multiphase flows. By appealing to the difference between slowly and rapidly varying quantities, it is shown that the natural

  3. Surface Flux Modeling for Air Quality Applications

    Science.gov (United States)

    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 c...

  4. 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.

  5. Initiation of CMEs by Magnetic Flux Emergence

    Indian Academy of Sciences (India)

    Keywords. Sun: corona, coronal mass ejections; magnetic fields; magnetohydrodynamics; flux emergence. Abstract. 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 ...

  6. Metamaterial anisotropic flux concentrators and magnetic arrays

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Smith, Anders; Bahl, Christian R.H.

    2013-01-01

    A metamaterial magnetic flux concentrator is investigated in detail in combination with a Halbach cylinder of infinite length. A general analytical solution to the field is determined and the magnetic figure of merit is determined for a Halbach cylinder with a flux concentrator. It is shown...

  7. Flux Noise in a Superconducting Transmission Line

    Science.gov (United States)

    Vasko, F. T.

    2017-08-01

    We study a superconducting transmission line (TL) formed by distributed L C oscillators and excited by external magnetic fluxes which are aroused from random magnetization (A ) placed in substrate or (B ) distributed at interfaces of a two-wire TL. The low-frequency dynamics of a random magnetic field is described based on the diffusion Langevin equation with a short-range source caused by (a ) a random amplitude or (b ) the gradient of magnetization. For a TL modeled as a two-port network with open and shorted ends, the effective magnetic flux at the open end has nonlocal dependency on noise distribution along the TL. The flux-flux correlation function is evaluated and analyzed for the regimes (A a ), (A b ), (B a ), and (B b ). Essential frequency dispersion takes place around the inverse diffusion time of random flux along the TL. Typically, noise effect increases with size faster than the area of the TL. The flux-flux correlator can be verified both via the population relaxation rate of the qubit, which is formed by the Josephson junction shunted by the TL with flux noises, and via random voltage at the open end of the TL.

  8. 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.

  9. 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.

  10. Measurement of a surface heat flux and temperature

    Science.gov (United States)

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

    1994-01-01

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

  11. Dynamics of particulate organic carbon flux in a global ocean model

    Directory of Open Access Journals (Sweden)

    I. D. Lima

    2014-02-01

    Biogeochemical Elemental Cycle to investigate the processes controlling the export of particulate organic matter from the euphotic zone and its flux to depth. We also compare model results with sediment trap data and other parameterizations of POC flux to depth to evaluate model skill and gain further insight into the causes of error and uncertainty in POC flux estimates. In the model, export ratios are mainly a function of diatom relative abundance and temperature while absolute fluxes and transfer efficiency are driven by mineral ballast composition of sinking material. The temperature dependence of the POC remineralization length scale is modulated by denitrification under low O2 concentrations and lithogenic (dust fluxes. Lithogenic material is an important control of transfer efficiency in the model, but its effect is restricted to regions of strong atmospheric dust deposition. In the remaining regions, CaCO3 content of exported material is the main factor affecting transfer efficiency. The fact that mineral ballast composition is inextricably linked to plankton community structure results in correlations between export ratios and ballast minerals fluxes (opal and CaCO3, and transfer efficiency and diatom relative abundance that do not necessarily reflect ballast or direct ecosystem effects, respectively. This suggests that it might be difficult to differentiate between ecosystem and ballast effects in observations. The model's skill in reproducing sediment trap observations is equal to or better than that of other parameterizations. However, the sparseness and relatively large uncertainties of sediment trap data makes it difficult to accurately evaluate the skill of the model and other parameterizations. More POC flux observations, over a wider range of ecological regimes, are necessary to thoroughly evaluate and test model results and better understand the processes controlling POC flux to depth in the ocean.

  12. 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

  13. Design comparison of single phase outer and inner-rotor hybrid excitation flux switching motor for hybrid electric vehicles

    Science.gov (United States)

    Mazlan, Mohamed Mubin Aizat; Sulaiman, Erwan; Husin, Zhafir Aizat; Othman, Syed Muhammad Naufal Syed; Khan, Faisal

    2015-05-01

    In hybrid excitation machines (HEMs), there are two main flux sources which are permanent magnet (PM) and field excitation coil (FEC). These HEMs have better features when compared with the interior permanent magnet synchronous machines (IPMSM) used in conventional hybrid electric vehicles (HEVs). Since all flux sources including PM, FEC and armature coils are located on the stator core, the rotor becomes a single piece structure similar with switch reluctance machine (SRM). The combined flux generated by PM and FEC established more excitation fluxes that are required to produce much higher torque of the motor. In addition, variable DC FEC can control the flux capabilities of the motor, thus the machine can be applied for high-speed motor drive system. In this paper, the comparisons of single-phase 8S-4P outer and inner rotor hybrid excitation flux switching machine (HEFSM) are presented. Initially, design procedures of the HEFSM including parts drawing, materials and conditions setting, and properties setting are explained. Flux comparisons analysis is performed to investigate the flux capabilities at various current densities. Then the flux linkages of PM with DC FEC of various DC FEC current densities are examined. Finally torque performances are analyzed at various armature and FEC current densities for both designs. As a result, the outer-rotor HEFSM has higher flux linkage of PM with DC FEC and higher average torque of approximately 10% when compared with inner-rotor HEFSM.

  14. Vertical fluxes of aromatic and aliphatic hydrocarbons in the Northwestern Mediterranean Sea

    Energy Technology Data Exchange (ETDEWEB)

    Deyme, Remi; Bouloubassi, Ioanna; Taphanel-Valt, Marie-Helene [Laboratoire d' Oceanographie et du Climat, Experimentation et Approches Numeriques (LOCEAN/IPSL), Universite Pierre et Marie Curie-CNRS-IRD-MNHN, UMR 7159, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Miquel, Juan-Carlos [Environment Laboratories, International Atomic Energy Agency, 4 Quai Antoine 1er, MC98000 Monaco, Principality of Monaco (Monaco); Lorre, Anne [Laboratoire d' Oceanographie et du Climat, Experimentation et Approches Numeriques (LOCEAN/IPSL), Universite Pierre et Marie Curie-CNRS-IRD-MNHN, UMR 7159, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Marty, Jean-Claude [CNRS- Universite Pierre et Marie Curie, UMR 7093, LOV, Observatoire oceanographique, 06234 Villefranche/mer (France); Mejanelle, Laurence, E-mail: laurence.mejanelle@upmc.fr [Laboratoire d' ECObiogeochimie Benthique, FRE3350, CNRS-Universite Pierre et Marie Curie, Avenue du Fontaule, 66650 Banyuls Sur Mer (France)

    2011-12-15

    Aliphatic and aromatic hydrocarbon fluxes were measured in time series sediment trap samples at 200 m and at 1000 m depths in the open Northwestern Mediterranean Sea, from December 2000 to July 2002. Averaged fluxes of n-alkanes, UCM and T-PAH{sub 35} were 2.96 {+-} 2.60 {mu}g m{sup -2} d{sup -1}, 64 {+-} 60 {mu}g m{sup -2} d{sup -1} and 0.68 {+-} 0.59 {mu}g m{sup -2} d{sup -1}, respectively. Molecular compositions of both hydrocarbon classes showed a contamination in petrogenic hydrocarbons well above the background levels of such an open site, whereas pyrolytic hydrocarbons stand in the range of other open Mediterranean locations. Fluxes displayed ample interannual and seasonal variabilities, mainly related to mass flux variation while concentration evolutions trigger secondary changes in pollutant fluxes. High lithogenic flux events exported particles with a larger pollutant load than biogenic particles formed during the spring bloom and during the summer. Sinking hydrocarbons were efficiently transported from 200 m to 1000 m. - Highlights: > PAH composition, plots of diagnostic PAH ratios and the UCM abundance indicate that non aromatic and aromatic hydrocarbons in sinking particles in the Ligurian Sea were mainly of petrogenic origin. > Fluxes of T-PAH35, n-alkanes and UCM transported downward at 200 m during the year 2001 were 269, 1218 and 26 910 mg m{sup -2} yr{sup -1}, respectively. > Vertical fluxes of aliphatic and aromatic hydrocarbons displayed ample seasonal and inter-annual variabilities, mainly related to mass flux variation. Concentration variation triggered smaller changes in pollutant fluxes. > High fluxes of lithogenic particles occurring from early January to early March 2001 transported about 45% of the annual vertical export of contaminants. In April-May, high fluxes of biogenic particles also transported a significant fraction of pollutants, despite the dilution of petrogenic and pyrolytic PAHs by biogenic material. - Vertical fluxes of

  15. Topology of magnetic flux ropes and formation of fossil flux transfer events and boundary layer plasmas

    Science.gov (United States)

    Lee, L. C.; Ma, Z. W.; Fu, Z. F.; Otto, A.

    1993-01-01

    A mechanism for the formation of fossil flux transfer events and the low-level boundary layer within the framework of multiple X-line reconnection is proposed. Attention is given to conditions for which the bulk of magnetic flux in a flux rope of finite extent has a simple magnetic topology, where the four possible connections of magnetic field lines are: IMF to MSP, MSP to IMF, IMF to IMF, and MSP to MSP. For a sufficient relative shift of the X lines, magnetic flux may enter a flux rope from the magnetosphere and exit into the magnetosphere. This process leads to the formation of magnetic flux ropes which contain a considerable amount of magnetosheath plasma on closed magnetospheric field lines. This process is discussed as a possible explanation for the formation of fossil flux transfer events in the magnetosphere and the formation of the low-latitude boundary layer.

  16. Benthic fluxes in San Francisco Bay

    Science.gov (United States)

    Hammond, Douglas E.; Fuller, C.; Harmon, D.; Hartman, Blayne; Korosec, M.; Miller, L.G.; Rea, R.; Warren, S.; Berelson, W.; Hager, S.W.

    1985-01-01

    Measurements of benthic fluxes have been made on four occasions between February 1980 and February 1981 at a channel station and a shoal station in South San Francisco Bay, using in situ flux chambers. On each occasion replicate measurements of easily measured substances such as radon, oxygen, ammonia, and silica showed a variability (??1??) of 30% or more over distances of a few meters to tens of meters, presumably due to spatial heterogeneity in the benthic community. Fluxes of radon were greater at the shoal station than at the channel station because of greater macrofaunal irrigation at the former, but showed little seasonal variability at either station. At both stations fluxes of oxygen, carbon dioxide, ammonia, and silica were largest following the spring bloom. Fluxes measured during different seasons ranged over factors of 2-3, 3, 4-5, and 3-10 (respectively), due to variations in phytoplankton productivity and temperature. Fluxes of oxygen and carbon dioxide were greater at the shoal station than at the channel station because the net phytoplankton productivity is greater there and the organic matter produced must be rapidly incorporated in the sediment column. Fluxes of silica were greater at the shoal station, probably because of the greater irrigation rates there. N + N (nitrate + nitrite) fluxes were variable in magnitude and in sign. Phosphate fluxes were too small to measure accurately. Alkalinity fluxes were similar at the two stations and are attributed primarily to carbonate dissolution at the shoal station and to sulfate reduction at the channel station. The estimated average fluxes into South Bay, based on results from these two stations over the course of a year, are (in mmol m-2 d-1): O2 = -27 ?? 6; TCO2 = 23 ?? 6; Alkalinity = 9 ?? 2; N + N = -0.3 ?? 0.5; NH3 = 1.4 ?? 0.2; PO4 = 0.1 ?? 0.4; Si = 5.6 ?? 1.1. These fluxes are comparable in magnitude to those in other temperate estuaries with similar productivity, although the seasonal

  17. 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.

  18. The Modified Fouling Index Ultrafiltration constant flux for assessing particulate/colloidal fouling of RO systems

    KAUST Repository

    Salinas-Rodriguez, Sergio G.

    2015-02-18

    Reliable methods for measuring and predicting the fouling potential of reverse osmosis (RO) feed water are important in preventing and diagnosing fouling at the design stage, and for monitoring pre-treatment performance during plant operation. The Modified Fouling Index Ultrafiltration (MFI-UF) constant flux is a significant development with respect to assessing the fouling potential of RO feed water. This research investigates (1) the variables influencing the MFI-UF test at constant flux filtration (membrane pore size, membrane material, flux rate); and (2) the application of MFI-UF into pre-treatment assessment and RO fouling estimation. The dependency of MFI on flux, means that to assess accurately particulate fouling in RO systems, the MFI should be measured at a flux similar to a RO system (close to 20 L/m2/h) or extrapolated from higher fluxes. The two studied membrane materials showed reproducible results; 10% for PES membranes and 6.3% for RC membranes. Deposition factors (amount of particles that remain on the surface of membrane) were measured in a full-scale plant ranging between 0.2 and 0.5. The concept of “safe MFI” is presented as a guideline for assessing pre-treatment for RO systems.

  19. Low Temperature Flux Growth of 2H-SiC and Beta-Gallium Oxide

    Science.gov (United States)

    Singh, N. B.; Choa, Fow-Sen; Su, Ching-Hua; Arnold, Bradley; Kelly, Lisa

    2016-01-01

    We present brief overview of our study on the low temperature flux growth of two very important novel wide bandgap materials 2H-SiC and Beta-gallium oxide (Beta-Ga2O3). We have synthesized and grown 5 millimeter to 1 centimeter size single crystals of Beta-gallium oxide (Beta-Ga2O3). We used a flux and semi wet method to grow transparent good quality crystals. In the semi-wet method Ga2O3 was synthesized with starting gallium nitrate solution and urea as a nucleation agent. In the flux method we used tin and other metallic flux. This crystal was placed in an alumina crucible and temperature was raised above 1050 degrees Centigrade. After a time period of thirty hours, we observed prismatic and needle shaped crystals of gallium oxide. Scanning electron microscopic studies showed step growth morphology. Crystal was polished to measure the properties. Bandgap was measured 4.7electronvolts using the optical absorption curve. Another wide bandgap hexagonal 2H-SiC was grown by using Si-Al eutectic flux in the graphite crucible. We used slight AlN also as the impurity in the flux. The temperature was raised up to 1050 degrees Centigrade and slowly cooled to 850 degrees Centigrade. Preliminary characterization results of this material are also reported.

  20. Neutrino flux prediction at MiniBooNE

    Science.gov (United States)

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

    2009-04-01

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

  1. Biosignatures in the Context of Low Energy Flux

    Science.gov (United States)

    Hoehler, T. M.

    2017-01-01

    Many of the features that are thought of as biosignatures - including the mediation of chemical and physical processes with speed, specificity, and selectivity - result directly or indirectly from life's unique capability to mediate and direct energy flux. As such, it is important to consider the impact that differences in energy flux may have on the quantity and quality of evidence for life. Earth differs from every other body in our solar system in the magnitude of biologically-usable energy flux into a liquid water environment. On a global basis, the capture of light energy into photosynthesis and the flux of chemical energy represented in the products of that photosynthesis (organic material + O2) are about six and four orders of magnitude larger, respectively, than the flux of energy represented in geochemical sources. Our conception of what an inhabited world "looks like" and our intuition about how to search for life are based in this high-energy context. Energy fluxes on worlds beyond Earth may be better approximated by the million-fold smaller flux provided to Earth's biosphere by geochemical sources. As a result, the nature, abundance, and quality of evidence for life that could be expected on an inhabited extraterrestrial world within our solar system may differ profoundly from that found on Earth. Understanding this potential difference in quantitative terms provides important context for the formulation of life detection strategies. The influence of energy flux on biosignatures can be evaluated through reference to the two basic purposes into which life partitions energy flux: (1) Life expends energy to sustain existing biomass in a metabolic steady state (metabolically functional but non-growing). The formal representation of this relationship in the traditional microbiology literature equates biomass directly with energy flux. The direct implication is that worlds having lower energy flux will have correspondingly lower potential to support biomass

  2. 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.

  3. Thermal problems on high flux beam lines

    Science.gov (United States)

    Avery, Robert T.

    1984-05-01

    Wiggler and undulator magnets can provide very intense photon flux densities to beam line components. This paper addresses some thermal/materials consequences due to such impingement. The LBL/Exxon/SSRL hybrid-wiggler beam line VI [1] now nearing operation will be able to provide up to ˜ 7 kW of total photon power at planned SPEAR operating conditions. The first masks are located at 6.5 m from the source and may receive a peak power density (transverse to the beam) exceeding 20 kW/cm 2. Significantly, this heat transfer rate exceeds that radiated from the sun's surface (7 kW/cm 2) and is comparable to that if welding torches. Clearly, cooling and configuration are of critical importance. Configurations for the first mask, the movable mask and the pivot mask on this beam line are presented together with considerations of thermal stress fatigue and of heat transfer by conduction to water-cooling circuits. Some preliminary information on the heating of crystals and mirrors is also presented. For the future, many additional intense wiggler/undulator beam lines are contemplated at several storage rings. The design of these beamlines would be enhanced by faster and more accurate computational techniques. LBL is developing a computer code which will be capable of giving photon power densities onto impinged surfaces for a wide range of source and beam line parameters. These include electron beam energy, current, emittance and orbit deviations; wiggler/undulator length, period and magnetic field; photon energy and angular distribution; reflection/absorption at intermediate impinged surfaces; defining apertures and focusing by mirrors. Three-dimensional computer programs for temperature, stress and strain have been available for some years, but "user friendly" versions are being sought. Other items to pursue are also suggested.

  4. Physical controls of oxygen fluxes at pelagic and benthic oxyclines in a lake

    DEFF Research Database (Denmark)

    Kreling, Julika; Bravidor, Jenny; McGinnis, Daniel F.

    2014-01-01

    d21, respectively). A one-dimensional transport model was used to estimate sources and sinks of oxygen potentially causing this imbalance. The model results indicate that 92% of dissolved oxygen transported into the oxycline is used by the respiration of organic material imported into the oxycline...... from the epilimnion; chemical oxygen consumption associated with the upward flux of reduced substances is negligible. Our findings indicate that under such conditions, dissolved oxygen consumption and therewith mineralization within the oxycline can be comparable with the corresponding rates occurring......We compared oxygen fluxes measured simultaneously at the pelagic and benthic oxycline in a lake and analyze their relation to hydrodynamic forcing conditions. While the mean oxygen fluxes did not differ significantly among both sites, the fluxes were highly variable in time. Short energetic periods...

  5. An improved flux-step method to determine the critical flux and the critical flux for irreversibility in a membrane bioreactor

    NARCIS (Netherlands)

    Marel, van der P.; Zwijnenburg, A.; Kemperman, A.; Wessling, M.; Temmink, B.G.; Meer, van der W.

    2009-01-01

    An improved flux-step method is presented incorporating cleaning steps by relaxation to determine the critical flux and the critical flux for irreversibility. Experiments are performed with activated sludge fed with real municipal wastewater. The improved flux-step method is compared with a common

  6. Reconciling heat-flux and salt-flux estimates at a melting ice-ocean interface

    CERN Document Server

    Keitzl, Thomas; Notz, Dirk

    2016-01-01

    The ratio of heat and salt flux is employed in ice-ocean models to represent ice-ocean interactions. In this study, this flux ratio is determined from direct numerical simulations of free convection beneath a melting, horizontal, smooth ice-ocean interface. We find that the flux ratio at the interface is three times as large as previously assessed based on turbulent-flux measurements in the field. As a consequence, interface salinities and melt rates are overestimated by up to 40\\% if they are based on the three-equation formulation. We also find that the interface flux ratio depends only very weakly on the far-field conditions of the flow. Lastly, our simulations indicate that estimates of the interface flux ratio based on direct measurements of the turbulent fluxes will be difficult because at the interface the diffusivities alone determine the mixing and the flux ratio varies with depth. As an alternative, we present a consistent evaluation of the flux ratio based on the total heat and salt fluxes across t...

  7. The “particle” flux: Origins and biological components

    Science.gov (United States)

    Silver, Mary W.; Gowing, Marcia M.

    study focuses on smaller or unicellular organisms; another study considers also the role of larger, but also cryptic, “swimmers”: MICHAELS, SILVER, GOWING and KNAUER, in press). The flux of non-living materials, including fecal pellets and amorphous aggregates, was not related to primary production, nor was there a correlation between obvious parameters of fecal pellets (i.e. average size or numbers) and production. These results raise questions about the meaning of the term “particle flux”. An average of at least 35%, with a range of 11-80% (minimal values, because larger organisms were not included), of the carbon flux leaving the euphotic zone consisted of algae, protozoans, and small metazoans that may have been executing vertical movements as part of a life history strategy. Furthermore, these organisms continued to be important in the mesopelagic zone, where the sarcodines were sometimes substantive contributors (average of 12%, range up to 49%) to the carbon flux. The declining contribution of these living organisms within traps at depth can account for some of the decreases in carbon flux that have been interpreted as “regeneration”. Clearly, reasonable inferences from traps require a better understanding of the nature of the “particles”, and particularly, the contribution of living organisms to trap collections.

  8. Materials screening chamber for testing materials resistance to atomic oxygen

    Science.gov (United States)

    Pippin, H. G.; Carruth, Ralph

    1989-01-01

    A unique test chamber for exposing material to a known flux of oxygen atoms is described. The capabilities and operating parameters of the apparatus include production of an oxygen atom flux in excess of 5 x 10 to the 16th atoms/sq cm-sec, controlled heating of the sample specimen, RF circuitry to contain the plasma within a small volume, and long exposure times. Flux measurement capabilities include a calorimetric probe and a light titration system. Accuracy and limitations of these techniques are discussed. An extension to the main chamber to allow simultaneous ultraviolet and atomic oxygen exposure is discussed. The oxygen atoms produced are at thermal energies. Sample specimens are maintained at any selected temperature between ambient and 200 C, to within + or - 2 C. A representative example of measurements made using the chamber is presented.

  9. A 2-D imaging heat-flux gauge

    Energy Technology Data Exchange (ETDEWEB)

    Noel, B.W.; Borella, H.M. (Los Alamos National Lab., NM (United States)); Beshears, D.L.; Sartory, W.K.; Tobin, K.W.; Williams, R.K. (Oak Ridge National Lab., TN (United States)); Turley, W.D. (EG and G Energy Measurements, Inc., Goleta, CA (United States). Santa Barbara Operations)

    1991-07-01

    This report describes a new leadless two-dimensional imaging optical heat-flux gauge. The gauge is made by depositing arrays of thermorgraphic-phosphor (TP) spots onto the faces of a polymethylpentene is insulator. In the first section of the report, we describe several gauge configurations and their prototype realizations. A satisfactory configuration is an array of right triangles on each face that overlay to form squares when the gauge is viewed normal to the surface. The next section of the report treats the thermal conductivity of TPs. We set up an experiment using a comparative longitudinal heat-flow apparatus to measure the previously unknown thermal conductivity of these materials. The thermal conductivity of one TP, Y{sub 2}O{sub 3}:Eu, is 0.0137 W/cm{center dot}K over the temperature range from about 300 to 360 K. The theories underlying the time response of TP gauges and the imaging characteristics are discussed in the next section. Then we discuss several laboratory experiments to (1) demonstrate that the TP heat-flux gauge can be used in imaging applications; (2) obtain a quantum yield that enumerates what typical optical output signal amplitudes can be obtained from TP heat-flux gauges; and (3) determine whether LANL-designed intensified video cameras have sufficient sensitivity to acquire images from the heat-flux gauges. We obtained positive results from all the measurements. Throughout the text, we note limitations, areas where improvements are needed, and where further research is necessary. 12 refs., 25 figs., 4 tabs.

  10. Factors controlling vertical fluxes of prrticles in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, T.M.B.; Ramaswamy, V.; Parthiban, G.; Shankar, R.

    whereas organic carbon percentages decreased. Particle flux patterns show a strong seasonality with peak fluxes during the southwest (SW) monsoon (June to September). Relatively high fluxes were also observed during the northeast (NE) monsoon (December...

  11. 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...

  12. High Thermal Conductivity Materials

    CERN Document Server

    Shinde, Subhash L

    2006-01-01

    Thermal management has become a ‘hot’ field in recent years due to a need to obtain high performance levels in many devices used in such diverse areas as space science, mainframe and desktop computers, optoelectronics and even Formula One racing cars! Thermal solutions require not just taking care of very high thermal flux, but also ‘hot spots’, where the flux densities can exceed 200 W/cm2. High thermal conductivity materials play an important role in addressing thermal management issues. This volume provides readers a basic understanding of the thermal conduction mechanisms in these materials and discusses how the thermal conductivity may be related to their crystal structures as well as microstructures developed as a result of their processing history. The techniques for accurate measurement of these properties on large as well as small scales have been reviewed. Detailed information on the thermal conductivity of diverse materials including aluminum nitride (AlN), silicon carbide (SiC), diamond, a...

  13. Final report of the HFIR (High Flux Isotope Reactor) irradiation facilities improvement project

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, B.H.; Thoms, K.R.; West, C.D.

    1987-09-01

    The High-Flux Isotope Reactor (HFIR) has outstanding neutronics characteristics for materials irradiation, but some relatively minor aspects of its mechanical design severely limited its usefulness for that purpose. In particular, though the flux trap region in the center of the annular fuel elements has a very high neutron flux, it had no provision for instrumentation access to irradiation capsules. The irradiation positions in the beryllium reflector outside the fuel elements also have a high flux; however, although instrumented, they were too small and too few to replace the facilities of a materials testing reactor. To address these drawbacks, the HFIR Irradiation Facilities Improvement Project consisted of modifications to the reactor vessel cover, internal structures, and reflector. Two instrumented facilities were provided in the flux trap region, and the number of materials irradiation positions in the removable beryllium (RB) was increased from four to eight, each with almost twice the available experimental space of the previous ones. The instrumented target facilities were completed in August 1986, and the RB facilities were completed in June 1987.

  14. On the Taxonomy of Flux Vacua

    Energy Technology Data Exchange (ETDEWEB)

    Giryavets, Alexander

    2004-04-25

    We investigate several predictions about the properties of IIB flux vacua on Calabi-Yau orientifolds, by constructing and characterizing a very large set of vacua in a specific example, an orientifold of the Calabi-Yau hypersurface in WP{sub 1,1,1,1,4}{sup 4}. We find support for the prediction of Ashok and Douglas that the density of vacua on moduli space is governed by det(-R-{omega}) where R and {omega} are curvature and Kaehler forms on the moduli space. The conifold point {psi} = 1 on moduli space therefore serves as an attractor, with a significant fraction of the flux vacua contained in a small neighborhood surrounding {psi} = 1. We also study the functional dependence of the number of flux vacua on the D3 charge in the fluxes, finding simple power law growth.

  15. 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.

  16. 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...

  17. 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.

  18. Recurrence Analysis of Eddy Covariance Fluxes

    Science.gov (United States)

    Lange, Holger; Flach, Milan; Foken, Thomas; Hauhs, Michael

    2015-04-01

    The eddy covariance (EC) method is one key method to quantify fluxes in biogeochemical cycles in general, and carbon and energy transport across the vegetation-atmosphere boundary layer in particular. EC data from the worldwide net of flux towers (Fluxnet) have also been used to validate biogeochemical models. The high resolution data are usually obtained at 20 Hz sampling rate but are affected by missing values and other restrictions. In this contribution, we investigate the nonlinear dynamics of EC fluxes using Recurrence Analysis (RA). High resolution data from the site DE-Bay (Waldstein-Weidenbrunnen) and fluxes calculated at half-hourly resolution from eight locations (part of the La Thuile dataset) provide a set of very long time series to analyze. After careful quality assessment and Fluxnet standard gapfilling pretreatment, we calculate properties and indicators of the recurrent structure based both on Recurrence Plots as well as Recurrence Networks. Time series of RA measures obtained from windows moving along the time axis are presented. Their interpretation is guided by three different questions: (1) Is RA able to discern periods where the (atmospheric) conditions are particularly suitable to obtain reliable EC fluxes? (2) Is RA capable to detect dynamical transitions (different behavior) beyond those obvious from visual inspection? (3) Does RA contribute to an understanding of the nonlinear synchronization between EC fluxes and atmospheric parameters, which is crucial for both improving carbon flux models as well for reliable interpolation of gaps? (4) Is RA able to recommend an optimal time resolution for measuring EC data and for analyzing EC fluxes? (5) Is it possible to detect non-trivial periodicities with a global RA? We will demonstrate that the answers to all five questions is affirmative, and that RA provides insights into EC dynamics not easily obtained otherwise.

  19. THERMAL CONDUCTIVITY OF HIGHLY POROUS MATERIALS

    Directory of Open Access Journals (Sweden)

    Rumyantsev Boris Mikhaylovich

    2012-10-01

    Heat fluxes inside aerated concrete are determined by the heat transfer driven by the filtration of the mixture of vapour and air and its convection inside cells. Products made of mineral cotton demonstrate accessible porosity; therefore, heat fluxes are determined by the properties of gas, or the air-vapour mixture under constant pressure. A convective heat flux is primarily dependent on the air permeability of the media and the characteristics (pressures and concentrations of internal and external surfaces of the material under research.

  20. One-dimensional Simulation of Heat Structure Melting and Evaporation Under High Heat Flux Condition Using MARS

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Geon-Woo; Lee, Jeong-Hun; Cho, Hyoung-Kyu; Park, Goon-Cherl [Seoul National University, Seoul (Korea, Republic of); Im, Kihak [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    In order to establish the successful application for high heat flux condition, it is necessary to analyze material damage including possible phase change such as melting and evaporation due to high heat flux. In addition, in terms of coolant, water which is widely used for coolant has serious concern in that critical heat flux (CHF) occurrence can degrade the cooling capability and aggravate the integrity of cooling components. However, MARS code cannot simulate the melting and evaporation of materials under high heat flux or heat generation condition by itself due to the absence of those models. In the present study, therefore, one dimensional heat conduction calculation module for heat structure melting and evaporation was developed and coupled with MARS to overcome the limitation of material phase change simulation capability in MARS code. As clarifying the high heat flux problem, plasma facing component of Korean demonstration fusion reactor, K-DEMO, was selected. The one-dimensional simulation of melting and evaporation of high heat flux component was performed using MARS and newly developed phase change simulation module. The target component and high heat flux condition were referred to geometry of plasma facing component in Korean fusion demonstration plant and fusion reactor's plasma disruption event. In order to simulate melting and evaporation, effective heat capacity method and evaporation model were applied to phase change simulation module. The simulation results showed several phenomena such as melting, evaporation and CHF occurrence in coolant channel.

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

    Science.gov (United States)

    Quek, Lake-Ee; Wittmann, Christoph; Nielsen, Lars K; Krömer, Jens O

    2009-05-01

    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. 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 (studies. By providing the software open source, we hope it will evolve with the rapidly growing field of fluxomics.

  2. Thermal decomposition of solder flux activators under simulated wave soldering conditions

    DEFF Research Database (Denmark)

    Piotrowska, Kamila; Jellesen, Morten Stendahl; Ambat, Rajan

    2017-01-01

    Purpose:The aim of this work is to investigate the decomposition behaviour of the activator species commonly used in the wave solder no-clean flux systems and to estimate the residue amount left after subjecting the samples to simulated wave soldering conditions. Design/methodology/approach: Chan......Purpose:The aim of this work is to investigate the decomposition behaviour of the activator species commonly used in the wave solder no-clean flux systems and to estimate the residue amount left after subjecting the samples to simulated wave soldering conditions. Design......-malic). The decomposition patterns of solder flux activators depend on their chemical nature, time of heat exposure and substrate materials. Evaporation of the residue from the surface of different materials (laminate with solder mask, copper surface or glass surface) was found to be more pronounced for succinic...

  3. The SeaFlux Turbulent Flux Dataset Version 1.0 Documentation

    Science.gov (United States)

    Clayson, Carol Anne; Roberts, J. Brent; Bogdanoff, Alec S.

    2012-01-01

    Under the auspices of the World Climate Research Programme (WCRP) Global Energy and Water cycle EXperiment (GEWEX) Data and Assessment Panel (GDAP), the SeaFlux Project was created to investigate producing a high-resolution satellite-based dataset of surface turbulent fluxes over the global oceans. The most current release of the SeaFlux product is Version 1.0; this represents the initial release of turbulent surface heat fluxes, associated near-surface variables including a diurnally varying sea surface temperature.

  4. Wedge Heat-Flux Indicators for Flash Thermography

    Science.gov (United States)

    Koshti, Ajay M.

    2003-01-01

    Wedge indicators have been proposed for measuring thermal radiation that impinges on specimens illuminated by flash lamps for thermographic inspection. Heat fluxes measured by use of these indicators would be used, along with known thermal, radiative, and geometric properties of the specimens, to estimate peak flash temperatures on the specimen surfaces. These indicators would be inexpensive alternatives to high-speed infrared pyrometers, which would otherwise be needed for measuring peak flash surface temperatures. The wedge is made from any suitable homogenous material such as plastic. The choice of material is governed by the equation given. One side of the wedge is covered by a temperature sensitive compound that decomposes irreversibly when its temperature exceeds a rated temperature (T-rated). The uncoated side would be positioned alongside or in place of the specimen and exposed to the flash, then the wedge thickness at the boundary between the white and blackened portions measured.

  5. Primary production, sinking fluxes and the microbial food web

    Science.gov (United States)

    Michaels, Anthony F.; Silver, Mary W.

    1988-04-01

    The size distribution of pelagic producers and the size and trophic position of consumers determine the composition and magnitude of sinking fluxes from the surface communities in a simple model of oceanic food webs. Picoplankton, the dominant producers in the model, contribute little to the sinking material, due primarily to the large number of trophic steps between picoplankton and the consumers that produce the sinking particles. Net phytoplankton are important contributors to the sinking materials, despite accounting for a small fraction of the total primary production. These net phytoplankton, especially those capable of nitrogen fixation, also dominate the fraction of the new production that is exported on its first pass through the food chain. The sinking flux is strongly determined by the community structure of the consumers and varies by an order of magnitude for different food webs. The model indicates that generalist grazers, zooplankton that consume a broad size spectrum of prey (including pico-and nanoplankton), play a critical role in exporting particles. The role of generalists that occasionally form swarms, such as thaliaceans (salps and doliolids), can be particularly difficult to assess. Short-term studies probably miss the relatively infrequent population blooms of these grazers, events that could control the average, long-term exports from surface oceanic communities.

  6. 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

  7. The impact of damming on riverine fluxes to the ocean: A case study from Eastern Iceland.

    Science.gov (United States)

    Eiriksdottir, Eydis Salome; Oelkers, Eric H; Hardardottir, Jorunn; Gislason, Sigurdur Reynir

    2017-04-15

    Anthropogenic water management has extensively altered the world's river systems through impoundments and channel diversions to meet the human's need for water, energy and transportation. To illuminate the effect of such activities on the environment, this study describes the impact of the installation of the Kárahnjúkar Dam in Eastern Iceland on the transport of riverine dissolved- and particulate material to the ocean by the Jökulsá á Dal and the Lagarfljót rivers. This dam, completed in 2007, collects water into the 2.2 km 3 Hálslón reservoir and diverts water from the glacial Jökulsá á Dal river into the partially glaciated Lagarfljót lagoon via a headrace tunnel. The impact of the damming was evaluated by sampling water from both the Jökulsá á Dal and the Lagarfljót rivers over a 15 year period spanning from 1998 to 2013. The annual flux of most dissolved elements increased substantially due to the damming. The fluxes of dissolved Zn, Al, Co, Ti and Fe increased most by damming; these fluxes increased by 46-391%. These differences can be attributed to changed saturation states of common secondary minerals in the Jökulsá á Dal due to reduced discharge, increased residence time and dissolution of suspended material, and, to a lesser degree, reduced photosynthesis due to less transparency in the Lagarfljót lagoon. The removal of particulate material and thus decreasing adsorption potential in the Jökulsá á Dal is the likely reason for the Fe flux increase. In contrast, approximately 85% of the original riverine transported mass of particulate material is trapped by the dam; that which passes tends to be relatively fine grained, increasing the average specific surface area of that which continues to flow towards the ocean. Consequently, the particulate geometric surface area flux is decreased by only 50% due to the damming. The blooming of silica diatoms during the spring consumes dissolved silica from the coastal waters until it becomes

  8. Particle fluxes in the Almeria-Oran Front: control by coastal upwelling and sea surface circulation

    Science.gov (United States)

    Sanchez-Vidal, A.; Calafat, A.; Canals, M.; Fabres, J.

    2004-12-01

    Particle flux data were obtained from one instrumented array moored under the direct influence of the Almeria-Oran Front (AOF) in the Eastern Alboran Sea, Western Mediterranean Sea, within the frame of the "Mediterranean Targeted Project II-MAss Transfer and Ecosystem Response" (MTPII-MATER) EU-funded research project. The mooring line was deployed from July 1997 to May 1998, and was equipped with three sequential sampling sediment trap-current meter pairs at 645, 1170 and 2210 m (30 m above the seafloor). The settling material was analysed to obtain total mass, organic carbon, opal, calcium carbonate and lithogenic fluxes. Qualitative analyses of SST and SeaWiFS images allowed monitoring the location and development of the Western and Eastern Alboran Sea gyres and associated frontal systems to determine their influence on particle fluxes. Particle flux time series obtained at the three depths showed a downward decrease of the time-weighed total mass flux annual means, thus illustrating the role of pelagic particle settling. The total mass flux was dominated by the lithogenic fraction followed by calcium carbonate, opal and organic carbon. The time series at the various depths were rather similar, with two strong synchronous biogenic peaks (up to 98 mg m -2 day -1 of organic carbon and 156 mg m -2 day -1 of opal) recorded in July 1997 and May 1998. Through comparing the fluctuations of the lithogenic and calcium carbonate-rich fluxes with the biogenic flux, we observed that the non-biogenic fluxes remained roughly constant, while the biogenic flux responded strongly to seasonal variations throughout the water column. Overall, the temporal variability of particle fluxes appeared to be linked to the evolution of several tens of kilometres in length sea surface hydrological structures and circulation of the Alboran Sea. Periodic southeastward advective displacements of waters from upwelling events off the southern Spanish coast were observed on SST and SeaWiFS images

  9. Accuracy of soil heat flux plate measurements in coarse substrates - Field measurements versus a laboratory test

    NARCIS (Netherlands)

    Weber, S.; Graf, A.; Heusinkveld, B.G.

    2007-01-01

    The in-situ performance of heat flux plates within coarse porous substrates might be limited due to poor contact between plate and substrate. We tested this behaviour with a simple laboratory set-up. Two test substrates were placed above a reference material of known thermal conductivity between a

  10. Export fluxes of dimethylsulfoniopropionate and its break down gases at the air-sea interface

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.; Shenoy, D.M.; Sarma, V.V.S.S.; George, M.D.; Dandekar, M.

    ]. However, material across the sea surface can also be transported along with aerosols, formed from bursting of bubbles, or by direct loss of NSS gases (formed from DMSP decomposi- tion) from the microlayer. These pathways can be significant for NSS flux...

  11. Effect of melter feed foaming on heat flux to the cold cap

    Czech Academy of Sciences Publication Activity Database

    Lee, S.; Hrma, P.; Pokorný, R.; Kloužek, Jaroslav; VanderVeer, B.J.; Dixon, D.R.; Luksic, S.A.; Rodriguez, C.P.; Chun, J.; Schweiger, M. J.; Kruger, A.A.

    2017-01-01

    Roč. 496, DEC 1 (2017), s. 54-65 ISSN 0022-3115 Institutional support: RVO:67985891 Keywords : cold cap * foam layer * heat flux * heat conductivity * evolved gas Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.048, year: 2016

  12. 16 CFR 1209.6 - Test procedures for critical radiant flux.

    Science.gov (United States)

    2010-01-01

    ... energy source. The radiant heat energy source shall be a panel of porous refractory material mounted in a... for monitoring and controlling the flow of fuel to the panel. (3) The radiant heat energy panel shall... radiant flux of exposed attic floor insulation using a radiant heat energy source. (a) Apparatus and...

  13. Biophysical regulations of carbon fluxes of a steppe and a cultivated cropland in semiarid Inner Mongolia

    Science.gov (United States)

    W.L. Zhang; S.P. Chen; J. Chen; L. Wei; X.G. Han; G.H. Lin

    2007-01-01

    An increasing amount of grasslands in Inner Mongolia of Northern China has been converted to cropland. The conversions in this extensive semiarid region have produced adverse ecological consequences at local and regional scales (e.g., dust storms). An important research need is to understand the fundamental ecosystem processes, such as energy and material fluxes,...

  14. Effect of flux powder SiO2 for the welding of 304-austenitic stainless ...

    African Journals Online (AJOL)

    . 1, 2017, pp. 34-45. 35. From the above literature, it can be conclude that most of the research was done for materials such as Steel, Nimonic 263 alloy,. Stainless Steel 308, Ferritic Stainless Steel and 202Stainless Steel with fluxes such as ...

  15. 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.

  16. 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.

  17. T2K neutrino flux prediction

    Science.gov (United States)

    Abe, K.; Abgrall, N.; Aihara, H.; Akiri, T.; Albert, J. B.; Andreopoulos, C.; Aoki, S.; Ariga, A.; Ariga, T.; Assylbekov, S.; Autiero, D.; Barbi, M.; Barker, G. J.; Barr, G.; Bass, M.; Batkiewicz, M.; Bay, F.; Bentham, S. W.; Berardi, V.; Berger, B. E.; Berkman, S.; Bertram, I.; Beznosko, D.; Bhadra, S.; Blaszczyk, F. d. M.; Blondel, A.; Bojechko, C.; Boyd, S.; Bravar, A.; Bronner, C.; Brook-Roberge, D. G.; Buchanan, N.; Calland, R. G.; Caravaca Rodríguez, J.; Cartwright, S. L.; Castillo, R.; Catanesi, M.-G.; Cervera, A.; Cherdack, D.; Christodoulou, G.; Clifton, A.; Coleman, J.; Coleman, S. J.; Collazuol, G.; Connolly, K.; Curioni, A.; Dabrowska, A.; Danko, I.; Das, R.; Davis, S.; Day, M.; de André, J. P. A. M.; de Perio, P.; De Rosa, G.; Dealtry, T.; Densham, C.; Di Lodovico, F.; Di Luise, S.; Dobson, J.; Duboyski, T.; Dufour, F.; Dumarchez, J.; Dytman, S.; Dziewiecki, M.; Dziomba, M.; Emery, S.; Ereditato, A.; Escudero, L.; Esposito, L. S.; Finch, A. J.; Frank, E.; Friend, M.; Fujii, Y.; Fukuda, Y.; Galymov, V.; Gaudin, A.; Giffin, S.; Giganti, C.; Gilje, K.; Golan, T.; Gomez-Cadenas, J. J.; Gonin, M.; Grant, N.; Gudin, D.; Guzowski, P.; Hadley, D. R.; Haesler, A.; Haigh, M. D.; Hansen, D.; Hara, T.; Hartz, M.; Hasegawa, T.; Hastings, N. C.; Hayato, Y.; Hearty, C.; Helmer, R. L.; Hignight, J.; Hillairet, A.; Himmel, A.; Hiraki, T.; Holeczek, J.; Horikawa, S.; Huang, K.; Hyndman, A.; Ichikawa, A. K.; Ieki, K.; Ieva, M.; Ikeda, M.; Imber, J.; Insler, J.; Ishida, T.; Ishii, T.; Ives, S. J.; Iyogi, K.; Izmaylov, A.; Jamieson, B.; Johnson, R. A.; Jo, J. H.; Jonsson, P.; Joo, K. K.; Jover-Manas, G. V.; Jung, C. K.; Kaji, H.; Kajita, T.; Kakuno, H.; Kameda, J.; Kanazawa, Y.; Karlen, D.; Karpikov, I.; Kearns, E.; Khabibullin, M.; Khanam, F.; Khotjantsev, A.; Kielczewska, D.; Kikawa, T.; Kilinski, A.; Kim, J. Y.; Kim, J.; Kim, S. B.; Kirby, B.; Kisiel, J.; Kitching, P.; Kobayashi, T.; Kogan, G.; Konaka, A.; Kormos, L. L.; Korzenev, A.; Koseki, K.; Koshio, Y.; Kowalik, K.; Kreslo, I.; Kropp, W.; Kubo, H.; Kudenko, Y.; Kumaratunga, S.; Kurjata, R.; Kutter, T.; Lagoda, J.; Laihem, K.; Laing, A.; Laveder, M.; Lawe, M.; Lee, K. P.; Licciardi, C.; Lim, I. T.; Lindner, T.; Lister, C.; Litchfield, R. P.; Longhin, A.; Lopez, G. D.; Ludovici, L.; Macaire, M.; Magaletti, L.; Mahn, K.; Malek, M.; Manly, S.; Marchionni, A.; Marino, A. D.; Marteau, J.; Martin, J. F.; Maruyama, T.; Marzec, J.; Masliah, P.; Mathie, E. L.; Matsumura, C.; Matsuoka, K.; Matveev, V.; Mavrokoridis, K.; Mazzucato, E.; McCauley, N.; McFarland, K. S.; McGrew, C.; McLachlan, T.; Messina, M.; Metelko, C.; Mezzetto, M.; Mijakowski, P.; Miller, C. A.; Minamino, A.; Mineev, O.; Mine, S.; Missert, A.; Miura, M.; Monfregola, L.; Moriyama, S.; Mueller, Th. A.; Murakami, A.; Murdoch, M.; Murphy, S.; Myslik, J.; Nagasaki, T.; Nakadaira, T.; Nakahata, M.; Nakai, T.; Nakajima, K.; Nakamura, K.; Nakayama, S.; Nakaya, T.; Nakayoshi, K.; Naples, D.; Nicholls, T. C.; Nielsen, C.; Nishikawa, K.; Nishimura, Y.; O'Keeffe, H. M.; Obayashi, Y.; Ohta, R.; Okumura, K.; Oryszczak, W.; Oser, S. M.; Otani, M.; Owen, R. A.; Oyama, Y.; Pac, M. Y.; Palladino, V.; Paolone, V.; Payne, D.; Pearce, G. F.; Perevozchikov, O.; Perkin, J. D.; Pinzon Guerra, E. S.; Plonski, P.; Poplawska, E.; Popov, B.; Posiadala, M.; Poutissou, J.-M.; Poutissou, R.; Przewlocki, P.; Quilain, B.; Radicioni, E.; Ratoff, P. N.; Ravonel, M.; Rayner, M. A.; Reeves, M.; Reinherz-Aronis, E.; Retiere, F.; Rodrigues, P. A.; Rondio, E.; Rossi, B.; Roth, S.; Rubbia, A.; Ruterbories, D.; Sacco, R.; Sakashita, K.; Sánchez, F.; Scantamburlo, E.; Scholberg, K.; Schwehr, J.; Scott, M.; Scully, D. I.; Seiya, Y.; Sekiguchi, T.; Sekiya, H.; Shibata, M.; Shiozawa, M.; Short, S.; Shustrov, Y.; Sinclair, P.; Smith, B.; Smith, R. J.; Smy, M.; Sobczyk, J. T.; Sobel, H.; Sorel, M.; Southwell, L.; Stamoulis, P.; Steinmann, J.; Still, B.; Sulej, R.; Suzuki, A.; Suzuki, K.; Suzuki, S. Y.; Suzuki, Y.; Szeglowski, T.; Szeptycka, M.; Tacik, R.; Tada, M.; Takahashi, S.; Takeda, A.; Takeuchi, Y.; Tanaka, H. A.; Tanaka, M.; Tanaka, M. M.; Taylor, I. J.; Terhorst, D.; Terri, R.; Thompson, L. F.; Thorley, A.; Tobayama, S.; Toki, W.; Tomura, T.; Totsuka, Y.; Touramanis, C.; Tsukamoto, T.; Tzanov, M.; Uchida, Y.; Ueno, K.; Vacheret, A.; Vagins, M.; Vasseur, G.; Wachala, T.; Waldron, A. V.; Walter, C. W.; Wang, J.; Wark, D.; Wascko, M. O.; Weber, A.; Wendell, R.; Wikström, G.; Wilkes, R. J.; Wilking, M. J.; Wilkinson, C.; Williamson, Z.; Wilson, J. R.; Wilson, R. J.; Wongjirad, T.; Yamada, Y.; Yamamoto, K.; Yanagisawa, C.; Yano, T.; Yen, S.; Yershov, N.; Yokoyama, M.; Yuan, T.; Zalewska, A.; Zambelli, L.; Zaremba, K.; Ziembicki, M.; Zimmerman, E. D.; Zito, M.; Żmuda, J.

    2013-01-01

    The Tokai-to-Kamioka (T2K) experiment studies neutrino oscillations using an off-axis muon neutrino beam with a peak energy of about 0.6 GeV that originates at the Japan Proton Accelerator Research Complex accelerator facility. Interactions of the neutrinos are observed at near detectors placed at 280 m from the production target and at the far detector—Super-Kamiokande—located 295 km away. The flux prediction is an essential part of the successful prediction of neutrino interaction rates at the T2K detectors and is an important input to T2K neutrino oscillation and cross section measurements. A FLUKA and GEANT3-based simulation models the physical processes involved in the neutrino production, from the interaction of primary beam protons in the T2K target, to the decay of hadrons and muons that produce neutrinos. The simulation uses proton beam monitor measurements as inputs. The modeling of hadronic interactions is reweighted using thin target hadron production data, including recent charged pion and kaon measurements from the NA61/SHINE experiment. For the first T2K analyses the uncertainties on the flux prediction are evaluated to be below 15% near the flux peak. The uncertainty on the ratio of the flux predictions at the far and near detectors is less than 2% near the flux peak.

  18. Untwisting Jets Related to Magnetic Flux Cancellation

    Science.gov (United States)

    Liu, Jiajia; Erdélyi, Robert; Wang, Yuming; Liu, Rui

    2018-01-01

    The rotational motion of solar jets is believed to be a signature of the untwisting process resulting from magnetic reconnection, which takes place between twisted closed magnetic loops (i.e., magnetic flux ropes) and open magnetic field lines. The identification of the pre-existing flux rope, and the relationship between the twist contained in the rope and the number of turns the jet experiences, are then vital in understanding the jet-triggering mechanism. In this paper, we will perform a detailed analysis of imaging, spectral, and magnetic field observations of four homologous jets, among which the fourth one releases a twist angle of 2.6π. Nonlinear force-free field extrapolation of the photospheric vector magnetic field before the jet eruption presents a magnetic configuration with a null point between twisted and open fields—a configuration highly in favor of the eruption of solar jets. The fact that the jet rotates in the opposite sense of handness to the twist contained in the pre-eruption photospheric magnetic field confirms the unwinding of the twist by the jet’s rotational motion. The temporal relationship between jets’ occurrence and the total negative flux at their source region, together with the enhanced magnetic submergence term of the photospheric Poynting flux, shows that these jets are highly associated with local magnetic flux cancellation.

  19. Detection of Metabolic Fluxes of O and H Atoms into Intracellular Water in Mammalian Cells

    Science.gov (United States)

    Kreuzer, Helen W.; Quaroni, Luca; Podlesak, David W.; Zlateva, Theodora; Bollinger, Nikki; McAllister, Aaron; Lott, Michael J.; Hegg, Eric L.

    2012-01-01

    Metabolic processes result in the release and exchange of H and O atoms from organic material as well as some inorganic salts and gases. These fluxes of H and O atoms into intracellular water result in an isotopic gradient that can be measured experimentally. Using isotope ratio mass spectroscopy, we revealed that slightly over 50% of the H and O atoms in the intracellular water of exponentially-growing cultured Rat-1 fibroblasts were isotopically distinct from growth medium water. We then employed infrared spectromicroscopy to detect in real time the flux of H atoms in these same cells. Importantly, both of these techniques indicate that the H and O fluxes are dependent on metabolic processes; cells that are in lag phase or are quiescent exhibit a much smaller flux. In addition, water extracted from the muscle tissue of rats contained a population of H and O atoms that were isotopically distinct from body water, consistent with the results obtained using the cultured Rat-1 fibroblasts. Together these data demonstrate that metabolic processes produce fluxes of H and O atoms into intracellular water, and that these fluxes can be detected and measured in both cultured mammalian cells and in mammalian tissue. PMID:22848359

  20. Flux-assisted synthesis of SnNb2O6 for tuning photocatalytic properties

    KAUST Repository

    Noureldine, Dalal

    2014-01-01

    A flux-assisted method was used to synthesize SnNb2O6 as a visible-light-responsive metal oxide photocatalyst. The role of flux was investigated in detail using different flux to reactant molar ratios (1 : 1, 3 : 1, 6 : 1, 10 : 1, and 14 : 1) and different reaction temperatures (300, 500, and 600 °C). The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), the Brunauer-Emmett-Teller method (BET), and high resolution scanning transmission electron microscopy (HRTEM). Flux-assisted synthesis led to tin niobate particles of platelet morphology with smooth surfaces. The synthesized crystal showed a 2D anisotropic growth along the (600) plane as the flux ratio increased. The particles synthesized with a high reactant to flux ratio (1 : 10 or higher) exhibited slightly improved photocatalytic activity for hydrogen evolution from an aqueous methanol solution under visible radiation (λ > 420 nm). The photo-deposition of platinum and PbO2 was examined to gain a better understanding of electrons and hole migration pathways in these layered materials. The HR-STEM observation revealed that no preferential deposition of these nanoparticles was observed depending on the surface facets of SnNb 2O6. This journal is © the Partner Organisations 2014.

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

    Science.gov (United States)

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

    2017-10-01

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

  2. Flux-assisted synthesis of SnNb2O6 for tuning photocatalytic properties.

    Science.gov (United States)

    Noureldine, Dalal; Anjum, Dalaver H; Takanabe, Kazuhiro

    2014-06-14

    A flux-assisted method was used to synthesize SnNb2O6 as a visible-light-responsive metal oxide photocatalyst. The role of flux was investigated in detail using different flux to reactant molar ratios (1 : 1, 3 : 1, 6 : 1, 10 : 1, and 14 : 1) and different reaction temperatures (300, 500, and 600 °C). The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), the Brunauer-Emmett-Teller method (BET), and high resolution scanning transmission electron microscopy (HRTEM). Flux-assisted synthesis led to tin niobate particles of platelet morphology with smooth surfaces. The synthesized crystal showed a 2D anisotropic growth along the (600) plane as the flux ratio increased. The particles synthesized with a high reactant to flux ratio (1 : 10 or higher) exhibited slightly improved photocatalytic activity for hydrogen evolution from an aqueous methanol solution under visible radiation (λ > 420 nm). The photo-deposition of platinum and PbO2 was examined to gain a better understanding of electrons and hole migration pathways in these layered materials. The HR-STEM observation revealed that no preferential deposition of these nanoparticles was observed depending on the surface facets of SnNb2O6.

  3. A magnetoelectric flux gate: new approach for weak DC magnetic field detection.

    Science.gov (United States)

    Chu, Zhaoqiang; Shi, Huaduo; PourhosseiniAsl, Mohammad Javad; Wu, Jingen; Shi, Weiliang; Gao, Xiangyu; Yuan, Xiaoting; Dong, Shuxiang

    2017-08-17

    The magnetic flux gate sensors based on Faraday's Law of Induction are widely used for DC or extremely low frequency magnetic field detection. Recently, as the fast development of multiferroics and magnetoelectric (ME) composite materials, a new technology based on ME coupling effect is emerging for potential devices application. Here, we report a magnetoelectric flux gate sensor (MEFGS) for weak DC magnetic field detection for the first time, which works on a similar magnetic flux gate principle, but based on ME coupling effect. The proposed MEFGS has a shuttle-shaped configuration made of amorphous FeBSi alloy (Metglas) serving as both magnetic and magnetostrictive cores for producing a closed-loop high-frequency magnetic flux and also a longitudinal vibration, and one pair of embedded piezoelectric PMN-PT fibers ([011]-oriented Pb(Mg,Nb)O3-PbTiO3 single crystal) serving as ME flux gate in a differential mode for detecting magnetic anomaly. In this way, the relative change in output signal of the MEFGS under an applied DC magnetic anomaly of 1 nT was greatly enhanced by a factor of 4 to 5 in comparison with the previous reports. The proposed ME flux gate shows a great potential for magnetic anomaly detections, such as magnetic navigation, magnetic based medical diagnosis, etc.

  4. TropFlux: air-sea fluxes for the global tropical oceans-description and evaluation

    Digital Repository Service at National Institute of Oceanography (India)

    PraveenKumar, B.; Vialard, J.; Lengaigne, M.; Murty, V.S.N.; McPhaden, M.J.

    This paper evaluates several timely, daily air-sea heat flux products (NCEP, NCEP2, ERA-Interim and OAFlux/ISCCP) against observations and present the newly developed TropFlux product. This new product uses bias-corrected ERA-interim and ISCCP data...

  5. 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.

  6. Estimating biological elementary flux modes that decompose a flux distribution by the minimal branching property

    DEFF Research Database (Denmark)

    Chan, Siu Hung Joshua; Solem, Christian; Jensen, Peter Ruhdal

    2014-01-01

    MOTIVATION: Elementary flux mode (EFM) is a useful tool in constraint-based modeling of metabolic networks. The property that every flux distribution can be decomposed as a weighted sum of EFMs allows certain applications of EFMs to studying flux distributions. The existence of biologically infea...... knowledge, which facilitates interpretation. Comparison of the methods applied to a complex flux distribution in Lactococcus lactis similarly showed the advantages of MBD. The minimal branching EFM concept underlying MBD should be useful in other applications.......MOTIVATION: Elementary flux mode (EFM) is a useful tool in constraint-based modeling of metabolic networks. The property that every flux distribution can be decomposed as a weighted sum of EFMs allows certain applications of EFMs to studying flux distributions. The existence of biologically......, i.e. minimal branching. RESULTS: We developed the concept of minimal branching EFM and derived the minimal branching decomposition (MBD) to decompose flux distributions. Testing in the core Escherichia coli metabolic network indicated that MBD can distinguish branches at branch points and greatly...

  7. About merging threshold and critical flux concepts into a single one: the boundary flux.

    Science.gov (United States)

    Stoller, Marco; Ochando-Pulido, Javier M

    2014-01-01

    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.

  8. Determination of surface fluxes using a Bowen ratio system | Kakane ...

    African Journals Online (AJOL)

    Components of the surface fluxes of the energy balance equation were determined using a Campbell Bowen ratio system. ... Soil heat flux (Qg) was measured with ground heat flux plates and the change in energy storage of the layer of soil above the heat flux plates was computed using direct measurements of soil ...

  9. 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 ...

  10. 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 ...

  11. 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

  12. Optimization-based design of heat flux manipulation devices with emphasis on fabricability.

    Science.gov (United States)

    Peralta, Ignacio; Fachinotti, Víctor D

    2017-07-24

    In this work, we present a new method for the design of heat flux manipulating devices, with emphasis on their fabricability. The design is obtained as solution of a nonlinear optimization problem where the objective function represents the given heat flux manipulation task, and the design variables define the material distribution in the device. In order to facilitate the fabrication of the device, the material at a given point is chosen from a set of predefined metamaterials. Each candidate material is assumed to be a laminate of materials with high conductivity contrast, so it is a metamaterial with a highly anisotropic effective conductivity. Following the discrete material optimization (DMO) approach, the fraction of each material at a given finite element of the mesh is defined as a function of continuous variables, which are ultimately the design variables. This DMO definition forces the fraction of each candidate to tend to either zero or one at the optimal solution. As an application example, we designed an easy-to-make device for heat flux concentration and cloaking.

  13. Stoichiometry and Life-History Interact to Determine the Magnitude of Cross-Ecosystem Element and Biomass Fluxes.

    Science.gov (United States)

    Luhring, Thomas M; DeLong, John P; Semlitsch, Raymond D

    2017-01-01

    Ecosystems are linked through the transfer of materials and energy. Studies examining material fluxes across habitat boundaries frequently quantify unidirectional flows of nutrients and energy. However, material fluxes can be multidirectional, and we lack a conceptual framework to describe how their quantity and stoichiometry influence the net transfer of individual elements between ecosystems. Here we develop a zero net transfer isocline (ZNTI) framework that integrates the relative mass and stoichiometry of fluxes into and out of an ecosystem. We then use case studies with amphibians and salmon to elucidate how life history, ontogenetic shifts in stoichiometry, and trophic interactions shape relative fluxes of nutrients between aquatic and terrestrial ecosystems. Because they increase in both size and Ca content from ova to metamorphs, amphibian life histories strongly bias them toward net Ca export into the terrestrial environment. Because amphibian biomass, C, P, and Ca ZNTIs do not overlap, there is no value of survivorship where the net flux of biomass, C, P, and Ca are simultaneously balanced between terrestrial and aquatic habitats. The degree of iteroparity and semelparity in salmon strongly affects both the magnitude of net biomass and P flux between riverine and marine environments. While the net direction of biomass flux generally remains strongly biased toward import into the riverine system, net P flux can reach net export into the marine environment because of increasing adult breeding survival leading to reduced mass and %P of what they deposit in rivers (e.g., ova vs. whole carcasses). These examples highlight how ontogenetic shifts in body size and stoichiometry result in asymmetric fluxes of elements and biomass that can lead to simultaneous net imports and exports of different elements within the same system. Furthermore, they demonstrate how changes in life-history characteristics and stage-specific survivorship can lead to changes in net

  14. Freezing E3-brane instantons with fluxes

    CERN Document Server

    Bianchi, Massimo; Martucci, Luca

    2012-01-01

    E3-instantons that generate non-perturbative superpotentials in IIB N=1 compactifications are more frequent 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-mode 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 worldvolume fluxes can be explicitly constructed in a one-modulus compactification, such that an E3-instanton has exactly two fermonic zero-modes. This construction is readily applicable to numerous scenarios.

  15. CO2 fluxes near a forest edge

    DEFF Research Database (Denmark)

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

    2008-01-01

    In contrast with recent advances on the dynamics of the flow at a forest edge, few studies have considered its role on scalar transport and, in particular, on CO2 transfer. The present study addresses the influence of the abrupt roughness change on forest atmosphere CO2 exchange and contrasts...... 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...

  16. 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.

  17. Warped Kähler potentials and fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Martucci, Luca [Dipartimento di Fisica ed Astronomia “Galileo Galilei' ,Università di Padova & I.N.F.N. Sezione di Padova,Via Marzolo 8, 35131 Padova (Italy)

    2017-01-13

    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.

  18. Internal analysis of a transverse flux sensor

    Science.gov (United States)

    Voyant, J.-Yves; Yonnet, J.-Paul; Jay, Guillaume; Foucher, Christian

    2005-04-01

    Rotary variable differential transformer (RVDT) sensors are used for industrial applications and are appreciated for their frictionless operation, reliability, linearity and sensitivity. The sensor shown here derives from a classic RVDT and is based on a differential rotating transformer. The functioning principle is explained and experimental measurements are shown. The originality of the studied sensor lies in the transverse flux design which gives a linearity error less than 0.1% of the stroke. However, this transverse flux circulation has uncommon features for an electrotechnical system due to flux paths which are not enclosed in radial planes. Finite element and experimental analysis are used for the magnetic study. This study aims to enhance sensor performances and manufacturing easiness.

  19. 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 brightness of Jupiter and Saturn at the three frequencies of the Planck Low Frequency Instrument (30, 44, and 70 GHz). The results provide constraints on the intrinsic brightness and the brightness time-variability of these planets. The majority of the planet flux density estimates are limited by systematic...... errors, but still yield better than 1% measurements in many cases. Applying data from Planck HFI, the Wilkinson Microwave Anisotropy Probe (WMAP), and the Atacama Cosmology Telescope (ACT) to a model that incorporates contributions from Saturn’s rings to the planet’s total flux density suggests a best...

  20. 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.

  1. Regulation of Na+ fluxes in plants

    Directory of Open Access Journals (Sweden)

    Frans eMaathuis

    2014-09-01

    Full Text Available When exposed to salt, every plant takes up Na+ from the environment. Once in the symplast, Na+ is distributed within cells and between different tissues and organs. There it can help to lower the cellular water potential but also exert potentially toxic effects. Control of Na+ fluxes is therefore crucial and indeed, research shows that the divergence between salt tolerant and salt sensitive plants is not due to a variation in transporter types but rather originates in the control of uptake and internal Na+ fluxes. A number of regulatory mechanisms has been identified based on signalling of Ca2+, cyclic nucleotides, reactive oxygen species, hormones, or on transcriptional and post translational changes of gene and protein expression. This review will give an overview of intra- and intercellular movement of Na+ in plants and will summarise our current ideas of how these fluxes are controlled and regulated in the early stages of salt stress.

  2. 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.

  3. Flux Analysis in Process Models via Causality

    Directory of Open Access Journals (Sweden)

    Ozan Kahramanoğulları

    2010-02-01

    Full Text Available We present an approach for flux analysis in process algebra models of biological systems. We perceive flux as the flow of resources in stochastic simulations. We resort to an established correspondence between event structures, a broadly recognised model of concurrency, and state transitions of process models, seen as Petri nets. We show that we can this way extract the causal resource dependencies in simulations between individual state transitions as partial orders of events. We propose transformations on the partial orders that provide means for further analysis, and introduce a software tool, which implements these ideas. By means of an example of a published model of the Rho GTP-binding proteins, we argue that this approach can provide the substitute for flux analysis techniques on ordinary differential equation models within the stochastic setting of process algebras.

  4. 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

  5. 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.

  6. 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.

  7. Cotunneling in pairs of coupled flux qubits

    Science.gov (United States)

    Lanting, T.; Harris, R.; Johansson, J.; Amin, M. H. S.; Berkley, A. J.; Gildert, S.; Johnson, M. W.; Bunyk, P.; Tolkacheva, E.; Ladizinsky, E.; Ladizinsky, N.; Oh, T.; Perminov, I.; Chapple, E. M.; Enderud, C.; Rich, C.; Wilson, B.; Thom, M. C.; Uchaikin, S.; Rose, G.

    2010-08-01

    We report measurements of macroscopic resonant tunneling between the two lowest energy states of a pair of magnetically coupled rf-superconducting quantum interference device flux qubits. This technique provides both a direct means of measuring the energy gap of the two-qubit system and a method for probing of the environment coupled to the pair of qubits. Measurements of the tunneling rate as a function of qubit flux bias show a Gaussian line shape that is well matched to theoretical predictions. Moreover, the peak widths indicate that each qubit is coupled to a local environment whose fluctuations are uncorrelated with that of the other qubit.

  8. High-flux cellulose acetate membranes

    Energy Technology Data Exchange (ETDEWEB)

    Boeddeker, K.W.; Finken, H.; Wenzlaff, A.

    1981-01-01

    Three routes to increase the permeate flux of asymmetric cellulose diacetate membranes of the Loeb-Sourirajan type are investigated: increasing the hydrophilicity of the membranes; increasing their compaction stability; employing a swelling agent which allows for higher solvent-to-polymer ratio in the casting solution. The effect of casting solution composition on flux and rejection of formamide-modified cellulose acetate membranes is shown in Figure 1, illustrating the general capability of this membrane type as function of solvent concentration. Membranes of casting solution composition cellulose diacetate/acetone/formamide 23/52/25 (solvent-to-polymer ratio 2.26) were used as reference membranes in this work.

  9. High-flux cellulose acetate membranes

    Energy Technology Data Exchange (ETDEWEB)

    Boeddeker, K.W.; Finken, H.; Wenzlaff, A.

    1981-01-01

    Three routes to increase the permeate flux of asymmetric cellulose diacetate membranes of the Loeb-Sourirajan type were investigated: increasing the hydrophilicity of the membranes; increasing their compaction stability, and employing a swelling agent which allows for higher solvent-to-polymer ratio in the casting solution. The effect of casting solution composition on flux and rejection of formamide-modified cellulose acetate membrane is included, illustrating the general capability of this membrane type as function of solvent concentration. Membranes of casting solution composition cellulose diacetate/acetone/formamide 23/52/25 were used as reference membranes in the work. 6 figures. (DP)

  10. Measuring the Magnetic Flux Density with Flux Loops and Hall Probes in the CMS Magnet Flux Return Yoke

    CERN Document Server

    Curé, B; Ball, A; Gaddi, A; Gerwig, H; Hervé, A; Klyukhin, V I; Loveless, R; Mulders, M

    2016-01-01

    The Compact Muon Solenoid (CMS) is a general purpose detector, designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with 6-m-diameter by 12.5-m-length free bore, enclosed inside a 10,000-ton return yoke made of construction steel. The flux return yoke consists of five dodecagonal three-layered barrel wheels and four end-cap disks at each end comprised of steel blocks up to 620 mm thick, which serve as the absorber plates of the muon detection system. To measure the field in and around the steel, a system of 22 flux loops and 82 3-D Hall sensors is installed on the return yoke blocks. A TOSCA 3-D model of the CMS magnet is developed to describe the magnetic field everywhere outside the tracking volume that was measured with the field-mapping machine. The voltages induced in the flux loops by the magnetic flux changing during the CMS magnet standard ramps down are measured with six 16-bit DAQ modules. The off-line inte...

  11. Carbon export fluxes in the Southern Ocean: results from inverse modeling and comparison with satellite based estimates

    OpenAIRE

    Schlitzer, Reiner

    2002-01-01

    The usage of dissolved nutrients and carbon for photosynthesis in the euphotic zone and the subsequent downward transport of particulate and dissolved organic material strongly affect the carbon concentrations in surface water and thus the air-sea exchange of CO2. Efforts to quantify the downward carbon flux for the whole ocean or on basin-scales are hampered by the sparseness of direct productivity or flux measurements. Here, a global ocean circulation, biogeochemical model is used to determ...

  12. Assessment of Spatial Representativeness of Eddy Covariance Flux Data from Flux Tower to Regional Grid

    Directory of Open Access Journals (Sweden)

    Hesong Wang

    2016-09-01

    Full Text Available Combining flux tower measurements with remote sensing or land surface models is generally regarded as an efficient method to scale up flux data from site to region. However, due to the heterogeneous nature of the vegetated land surface, the changing flux source areas and the mismatching between ground source areas and remote sensing grids, direct use of in-situ flux measurements can lead to major scaling bias if their spatial representativeness is unknown. Here, we calculate and assess the spatial representativeness of 15 flux sites across northern China in two aspects: first, examine how well a tower represents fluxes from the specific targeted vegetation type, which is called vegetation-type level; and, second, examine how representative is the flux tower footprint of the broader landscape or regional extents, which is called spatial-scale level. We select fraction of target vegetation type (FTVT and Normalized Difference Vegetation Index (NDVI as key indicators to calculate the spatial representativeness of 15 EC sites. Then, these sites were ranked into four grades based on FTVT or cluster analysis from high to low in order: (1 homogeneous; (2 representative; (3 acceptable; and (4 disturbed measurements. The results indicate that: (1 Footprint climatology for each site was mainly distributed in an irregular shape, had similar spatial pattern as spatial distribution of prevailing wind direction; (2 At vegetation-type level, the number of homogeneous, representative, acceptable and disturbed measurements is 8, 4, 1 and 2, respectively. The average FTVT was 0.83, grass and crop sites had greater representativeness than forest sites; (3 At spatial-scale level, flux sites with zonal vegetation had greater representativeness than non-zonal vegetation sites, and the scales were further divided into three sub-scales: (a in flux site scale, the average of absolute NDVI bias was 4.34%, the number of the above four grades is 9, 4, 1 and 1, respectively

  13. 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

  14. Phosphorus Phase Associations in the Deep Ocean Particle Flux in the Sargasso Sea

    Science.gov (United States)

    Carter, A. M.; Conte, M. H.; Weber, J. C.; Shaw, L.

    2016-02-01

    The carrier phases of phosphorus influence its flux and remineralization in the water column and burial in ocean sediments. Sequential extraction methods (SEDEX, Ruttenberg et al. 1992) have been developed to measure sedimentary phosphorus associated with specific mineral analogs, however these may not be representative of key carrier phases in the water column. To better understand P carrier phases in the deep particle flux, we applied a modified SEDEX method to partition P in sinking particles collected by the Oceanic Flux Program sediment traps (500m, 1500m and 3200m depths) into seven fractions, which were then analyzed by ICPMS for elemental composition. The samples spanned a time period from Nov 2008 (seasonal flux minimum) to Mar 2009 (spring bloom). At 500m depth, approximately 75% of the total P flux ( 200 ugP m-2 d-1) was loosely sorbed and released into the supernatant during sample collection. This flux of loosely-sorbed P decreased by an order of magnitude between 500 and 1500m depths, and by 3200m depth constituted only 25% of the total P flux ( 40 ugP m-2 d-1). In contrast, the P flux in non-soluble phases decreased by only 50% between 500m ( 55 ugP m-2 d-1) and 3200m ( 34 ugP m-2 d-1) depths. SEDEX/ICPMS results indicate that the distribution of P among non-soluble carrier phases varies little with depth: approximately 30-35% is associated with Mn-Fe hydroxides, 20-30% with opal, and 15-30% with carbonate/authigenic P/biogenic apatite phases. Smaller fractions are associated with ion exchangeable phases (12-15%), detrital apatite (4-8%), and refractory organics and inorganic minerals released by a final ashing/acid extraction step (1-4%). There is a small trend toward more recalcitrant Mn-Fe hydroxides and opal carrier phases with depth. The P flux associated with Mn/Fe hydroxides and opal (and at 500m, ion exchangeable material) showed strong seasonality and covaried over the time-series with peak fluxes during the spring bloom, while P fluxes

  15. River inputs and organic matter fluxes in the northern Bay of Bengal: Fatty acids

    Digital Repository Service at National Institute of Oceanography (India)

    Reemtsma, T.; Ittekkot, V.; Bartsch, M.; Nair, R.R.

    period. It was ascribed to the flooding of ox-bow lakes in the delta and the drainage of degraded organic material deposited there. 3.2. Temporal development of terri genous and marine fatty acid fluxes 90. 60' 'E v 30' B00' soo. 400" 200' a... with falling water. A comparable mechanism, the inter- mediate storage within ox-bow lakes in the flood plains, was suggested for the Ganges (It- tekkot et al., 1986). The marine fatty acid flux has an additional third maximum in July (Fig. 5b, No. 8...

  16. Activity of the European high heat flux test facility: FE200

    Energy Technology Data Exchange (ETDEWEB)

    Bobin-Vastra, I. [AREVA Centre Technique de Framatome, FE200, Porte Magenta BP181, 71200 Le Creusot Cedex (France) and EFDA Close Support Unit, Boltzmannstr. 2, D-85748 Garching (Germany)]. E-mail: isabelle.bobinvastra@framatome-anp.com; Escourbiac, F. [Association Euratom-CEA, CEA/DSM/DRFC, CEA/Cadarache, F-13108 Saint Paul lez Durance (France)]. E-mail: escourbi@drfc.cad.cea.fr; Merola, M. [EFDA Close Support Unit, Boltzmannstr. 2, D-85748 Garching (Germany)]. E-mail: mario.merola@tech.efda.org; Lorenzetto, P. [EFDA Close Support Unit, Boltzmannstr. 2, D-85748 Garching (Germany)]. E-mail: lorenzp@tech.efda.org

    2005-11-15

    FE200 is an electron beam (EB) 200 kW test facility resulting since 1991 from partnership between Framatome Technical Centre in Le Creusot (France) and Tore Supra team in CEA Cadarache (France). It is dedicated to high heat flux testing of small and medium-sized plasma facing components. The performed tests are thermal fatigue tests (100,000 since 1992), critical heat fluxes, disruptions, glancing incidence tests on materials such as Cu-Al25 and CuCrZr alloys, carbon fibre composite (CFC) or tungsten (W). The thermal fatigue behaviour of some primary first wall (PFW), hypervapotron and divertor components is described.

  17. Crystal growth of Ba 3BP 3O 12 with BPO 4-NaF flux

    Science.gov (United States)

    Zhang, Zhi-Jun; Wang, Hong; Hu, Guan-Qin; Chen, Hao-Hong; Yang, Xin-Xin; Zhao, Jing-Tai

    2010-04-01

    Single crystals of Ba 3BP 3O 12 with size of 10×8×2 mm 3 have been grown by the top-seeded solution growth (TSSG) method using BPO 4-NaF mixture as the flux. The crystals were characterized by X-ray powder diffraction, field emission scanning electron microscopy (FE-SEM) and transmittance spectrum. Ba 3BP 3O 12 single crystal exhibits wide transparency in the range 250-800 nm. The preparation process of starting materials and the effect of flux on the crystal growth were discussed.

  18. Modelisation and distribution of neutron flux in radium-beryllium source (226Ra-Be)

    Science.gov (United States)

    Didi, Abdessamad; Dadouch, Ahmed; Jai, Otman

    2017-09-01

    Using the Monte Carlo N-Particle code (MCNP-6), to analyze the thermal, epithermal and fast neutron fluxes, of 3 millicuries of radium-beryllium, for determine the qualitative and quantitative of many materials, using method of neutron activation analysis. Radium-beryllium source of neutron is established to practical work and research in nuclear field. The main objective of this work was to enable us harness the profile flux of radium-beryllium irradiation, this theoretical study permits to discuss the design of the optimal irradiation and performance for increased the facility research and education of nuclear physics.

  19. Materials Chemistry

    CERN Document Server

    Fahlman, Bradley D

    2011-01-01

    The 2nd edition of Materials Chemistry builds on the strengths that were recognized by a 2008 Textbook Excellence Award from the Text and Academic Authors Association (TAA). Materials Chemistry addresses inorganic-, organic-, and nano-based materials from a structure vs. property treatment, providing a suitable breadth and depth coverage of the rapidly evolving materials field. The 2nd edition continues to offer innovative coverage and practical perspective throughout. After briefly defining materials chemistry and its history, seven chapters discuss solid-state chemistry, metals, semiconducting materials, organic "soft" materials, nanomaterials, and materials characterization. All chapters have been thoroughly updated and expanded with, for example, new sections on ‘soft lithographic’ patterning, ‘click chemistry’ polymerization, nanotoxicity, graphene, as well as many biomaterials applications. The polymer and ‘soft’ materials chapter represents the largest expansion for the 2nd edition. Each ch...

  20. Particle and heat flux estimates in Proto-MPEX in Helicon Mode with IR imaging

    Science.gov (United States)

    Showers, M. A.; Biewer, T. M.; Caughman, J. B. O.; Donovan, D. C.; Goulding, R. H.; Rapp, J.

    2016-10-01

    The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) at Oak Ridge National Laboratory (ORNL) is a linear plasma device developing the plasma source concept for the Material Plasma Exposure eXperiment (MPEX), which will address plasma material interaction (PMI) science for future fusion reactors. To better understand how and where energy is being lost from the Proto-MPEX plasma during ``helicon mode'' operations, particle and heat fluxes are quantified at multiple locations along the machine length. Relevant diagnostics include infrared (IR) cameras, four double Langmuir probes (LPs), and in-vessel thermocouples (TCs). The IR cameras provide temperature measurements of Proto-MPEX's plasma-facing dump and target plates, located on either end of the machine. The change in surface temperature is measured over the duration of the plasma shot to determine the heat flux hitting the plates. The IR cameras additionally provide 2-D thermal load distribution images of these plates, highlighting Proto-MPEX plasma behaviors, such as hot spots. The LPs and TCs provide additional plasma measurements required to determine particle and heat fluxes. Quantifying axial variations in fluxes will help identify machine operating parameters that will improve Proto-MPEX's performance, increasing its PMI research capabilities. This work was supported by the U.S. D.O.E. contract DE-AC05-00OR22725.

  1. High heat flux single phase heat exchanger

    Science.gov (United States)

    Valenzuela, Javier A.; Izenson, Michael G.

    1990-01-01

    This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

  2. 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…

  3. Exponentially tapered Josephson flux-flow oscillator

    DEFF Research Database (Denmark)

    Benabdallah, A.; Caputo, J. G.; Scott, Alwyn C.

    1996-01-01

    We introduce an exponentially tapered Josephson flux-flow oscillator that is tuned by applying a bias current to the larger end of the junction. Numerical and analytical studies show that above a threshold level of bias current the static solution becomes unstable and gives rise to a train of flu...

  4. Fast flux test facility hazards assessment

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, L.N.

    1994-10-24

    This document establishes the technical basis in support of Emergency Planning Activities for the Fast Flux Test Facility on the Hanford Site. The document represents an acceptable interpretation of the implementing guidance document for DOE Order 5500.3A. Through this document, the technical basis for the development of facility specific Emergency Action Levels and the Emergency Planning Zone is demonstrated.

  5. 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.

  6. On The Vibrational Flux in Bounded Atoms

    CERN Document Server

    Caturello, Naidel A M dos S

    2011-01-01

    In this paper we derived a model based on general assumptions and allowed us to derive some important thermodynamic functions that are time-dependent, also we could see the behavior of these functions by surfaces. The model is based on independent movements that couple and construct a flux, which makes the system as a whole not to be independent at all.

  7. 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

  8. Diameter effect on critical heat flux

    Energy Technology Data Exchange (ETDEWEB)

    Tanase, A. [University of Ottawa, Department of Mechanical Engineering, Ottawa, ON (Canada)], E-mail: atana052@uottawa.ca; Cheng, S.C. [University of Ottawa, Department of Mechanical Engineering, Ottawa, ON (Canada); Groeneveld, D.C. [University of Ottawa, Department of Mechanical Engineering, Ottawa, ON (Canada); Chalk River Laboratories, Atomic Energy of Canada Ltd., Chalk River, ON (Canada); Shan, J.Q. [Department of Nuclear Engineering, Xi' an Jiaotong University (China)

    2009-02-15

    The critical heat flux look-up table (CHF LUT) is widely used to predict CHF for various applications, including design and safety analysis of nuclear reactors. Using the CHF LUT for round tubes having inside diameters different from the reference 8 mm involves conversion of CHF to 8 mm. Different authors [Becker, K.M., 1965. An Analytical and Experimental Study of Burnout Conditions in Vertical Round Ducts, Aktiebolaget Atomenergie Report AE 177, Sweden; Boltenko, E.A., et al., 1989. Effect of tube diameter on CHF at various two phase flow regimes, Report IPE-1989; Biasi, L., Clerici, G.C., Garriba, S., Sala, R., Tozzi, A., 1967. Studies on Burnout, Part 3, Energia Nucleare, vol. 14, pp. 530-536; Groeneveld, D.C., Cheng, S.C., Doan, T., 1986. AECL-UO critical heat flux look-up table. Heat Transfer Eng., 7, 46-62; Groeneveld et al., 1996; Hall, D.D., Mudawar, I., 2000. Critical heat flux for water flow in tubes - II subcooled CHF correlations. Int. J. Heat Mass Transfer, 43, 2605-2640; Wong, W.C., 1996. Effect of tube diameter on critical heat flux, MaSC dissertation, Ottawa Carleton Institute for Mechanical and Aeronautical Engineering, University of Ottawa] have proposed several types of correlations or factors to describe the diameter effect on CHF. The present work describes the derivation of new diameter correction factor and compares it with several existing prediction methods.

  9. Flux-corrected transport principles, algorithms, and applications

    CERN Document Server

    Löhner, Rainald; Turek, Stefan

    2012-01-01

    Many modern high-resolution schemes for Computational Fluid Dynamics trace their origins to the Flux-Corrected Transport (FCT) paradigm. FCT maintains monotonicity using a nonoscillatory low-order scheme to determine the bounds for a constrained high-order approximation. This book begins with historical notes by J.P. Boris and D.L. Book who invented FCT in the early 1970s. The chapters that follow describe the design of fully multidimensional FCT algorithms for structured and unstructured grids, limiting for systems of conservation laws, and the use of FCT as an implicit subgrid scale model. The second edition presents 200 pages of additional material. The main highlights of the three new chapters include: FCT-constrained interpolation for Arbitrary Lagrangian-Eulerian methods, an optimization-based approach to flux correction, and FCT simulations of high-speed flows on overset grids. Addressing students and researchers, as well as CFD practitioners, the book is focused on computational aspects and contains m...

  10. Coupling of Sinking Biogenic Particulate Fluxes and Primary Production in the Euphotic Zone of the Cariaco Basin, Venezuela

    Science.gov (United States)

    Montes-Herrera, E.; Muller-Karger, F. E.; Thunell, R.; Hollander, D.; Astor, Y.; Varela, R.; Soto, I.; Lorenzoni, L.

    2007-12-01

    Only 1% of the organic matter produced in the upper ocean by photosynthesis reaches depths below 1500 m due to dissolution and microbial degradation. Recent work shows that the vertical flux of particulate organic carbon (POC) is strongly correlated with the settling flux of minerals like calcium carbonate, opal and lithogenic material. These act as ballast and also provide physical protection against degradation of POC. Results from the CARIACO (Carbon Retention in a Colored Ocean) time series program support this hypothesis. For over ten years, CARIACO has been studying the connections between primary production (PP) and the biogeochemical features of sinking particles in the Cariaco Basin, Venezuela, with moored sediment traps that collect settling matter at five depths between 125 and 1300 m on a bi-weekly basis. The geomorphology of the basin restricts deep water ventilation, leading to anoxia below 250 m. Although the Cariaco Basin exhibits strong seasonal production cycles related to wind-driven upwelling, the flux of biogenic matter at all depths below the oxic-anoxic interface is not significantly correlated to primary production. In order to understand the flux of particles in the upper 100 m of the water column, deployments of drifting sediment traps in the Cariaco Basin were carried out from March to July 2007, collecting settling material at 50 and 100 m. The hypothesis is that the flux of sinking material through the euphotic zone may be less affected by decomposition and dissolution than material reaching the deep moored traps. Initial results show significant differences in POC, PON and carbonate flux rates between 50 and 100 m. They also exhibit significant differences in the flux rates of these components between upwelling vs. relaxation periods, suggesting potential connections among seasonal changes in surface chlorophyll a concentrations, plankton community structure, and the vertical export of biogenic materials. We describe results from this

  11. Mesoscopic fluctuations in biharmonically driven flux qubits

    Science.gov (United States)

    Ferrón, Alejandro; Domínguez, Daniel; Sánchez, María José

    2017-01-01

    We investigate flux qubits driven by a biharmonic magnetic signal, with a phase lag that acts as an effective time reversal broken parameter. The driving induced transition rate between the ground and the excited state of the flux qubit can be thought of as an effective transmittance, profiting from a direct analogy between interference effects at avoided level crossings and scattering events in disordered electronic systems. For time scales prior to full relaxation, but large compared to the decoherence time, this characteristic rate has been accessed experimentally by Gustavsson et al. [Phys. Rev. Lett. 110, 016603 (2013)], 10.1103/PhysRevLett.110.016603 and its sensitivity with both the phase lag and the dc flux detuning explored. In this way, signatures of universal conductance fluctuationslike effects have been analyzed and compared with predictions from a phenomenological model that only accounts for decoherence, as a classical noise. Here we go beyond the classical noise model and solve the full dynamics of the driven flux qubit in contact with a quantum bath employing the Floquet-Born-Markov master equation. Within this formalism, the computed relaxation and decoherence rates turn out to be strongly dependent on both the phase lag and the dc flux detuning. Consequently, the associated pattern of fluctuations in the characteristic rates display important differences with those obtained within the mentioned phenomenological model. In particular, we demonstrate the weak localizationlike effect in the average values of the relaxation rate. Our predictions can be tested for accessible but longer time scales than the current experimental times.

  12. Periodontal materials

    National Research Council Canada - National Science Library

    Darby, I

    2011-01-01

    .... However, the last 30 years have seen the development of materials used in regeneration of the periodontal tissues following periodontal disease, guided tissue regeneration, and the use of these materials in bone...

  13. Analytic materials.

    Science.gov (United States)

    Milton, Graeme W

    2016-11-01

    The theory of inhomogeneous analytic materials is developed. These are materials where the coefficients entering the equations involve analytic functions. Three types of analytic materials are identified. The first two types involve an integer p. If p takes its maximum value, then we have a complete analytic material. Otherwise, it is incomplete analytic material of rank p. For two-dimensional materials, further progress can be made in the identification of analytic materials by using the well-known fact that a 90(°) rotation applied to a divergence-free field in a simply connected domain yields a curl-free field, and this can then be expressed as the gradient of a potential. Other exact results for the fields in inhomogeneous media are reviewed. Also reviewed is the subject of metamaterials, as these materials provide a way of realizing desirable coefficients in the equations.

  14. Hazardous materials

    Science.gov (United States)

    ... words like: Acid Alkali Carcinogenic Caution Corrosive Danger Explosive Flammable Irritant Radioactive Unstable Warning A label called the Material Safety Data Sheet (MSDS) will tell you if a material is ...

  15. Contrast Materials

    Science.gov (United States)

    ... safe are contrast materials? Contrast materials are safe drugs; adverse reactions ranging from mild to severe do occur but ... the use of medications such as Beta blockers , NSAIDs , interleukin 2 having received a large amount of ...

  16. Composite Materials

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    materials. Numerical procedures are outlined which facilitate the practical analysis of any feature considered in this book. Examples are presented which illustrate the analysis of well-known materials such as concrete, hardening cement paste, ceramics, tile, wood, impregnated and reinforced materials...

  17. Improving SWAT for simulating water and carbon fluxes of forest ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Qichun; Zhang, Xuesong

    2016-11-01

    As a widely used watershed model for assessing impacts of anthropogenic and natural disturbances on water quantity and quality, the Soil and Water Assessment Tool (SWAT) has not been extensively tested in simulating water and carbon fluxes of forest ecosystems. Here, we examine SWAT simulations of evapotranspiration (ET), net primary productivity (NPP), net ecosystem exchange (NEE), and plant biomass at ten AmeriFlux forest sites across the U.S. We identify unrealistic radiation use efficiency (Bio_E), large leaf to biomass fraction (Bio_LEAF), and missing phosphorus supply from parent material weathering as the primary causes for the inadequate performance of the default SWAT model in simulating forest dynamics. By further revising the relevant parameters and processes, SWAT’s performance is substantially improved. Based on the comparison between the improved SWAT simulations and flux tower observations, we discuss future research directions for further enhancing model parameterization and representation of water and carbon cycling for forests.

  18. On the Heat Flux Vector and Thermal Conductivity of Slags: A Brief Review

    Directory of Open Access Journals (Sweden)

    Mehrdad Massoudi

    2016-01-01

    Full Text Available The viscosity and the thermal conductivity of slag are among two of the most important material properties that need to be studied. In this paper we review the existing theoretical and experimental correlations for the thermal conductivity of slag. However, since, in general, slag behaves as a non-linear fluid, it is the heat flux vector which must be studied. Both explicit and implicit approaches are discussed and suggestions about the form of the heat flux vector and the thermal conductivity and their dependence on shear rate, porosity, deformation, etc. are provided. The discussion of the constitutive modeling of the heat flux vector for slag is from a theoretical perspective.

  19. Communication: On the calculation of time-dependent electron flux within the Born-Oppenheimer approximation: A flux-flux reflection principle.

    Science.gov (United States)

    Albert, Julian; Hader, Kilian; Engel, Volker

    2017-12-28

    It is commonly assumed that the time-dependent electron flux calculated within the Born-Oppenheimer (BO) approximation vanishes. This is not necessarily true if the flux is directly determined from the continuity equation obeyed by the electron density. This finding is illustrated for a one-dimensional model of coupled electronic-nuclear dynamics. There, the BO flux is in perfect agreement with the one calculated from a solution of the time-dependent Schrödinger equation for the coupled motion. A reflection principle is derived where the nuclear BO flux is mapped onto the electronic flux.

  20. Modern perspectives on measuring and interpreting seafloor heat flux

    Science.gov (United States)

    Harris, Reid N.; Fisher, A.; Ruppel, C.; Martinez, F.

    2008-01-01

    There has been a resurgence of interest in marine heat flow in the past 10–15 years, coinciding with fundamental achievements in understanding the Earth's thermal state and quantifying the dynamics and impacts of material and energy fluxes within and between the lithosphere and hydrosphere. At the same time, technical capabilities have dwindled to the point that no U.S. academic institution currently operates a seagoing heat flow capacity.In September 2007, a workshop was convened in Salt Lake City with sponsorship from the U.S. National Science Foundation (NSF) and participation by scientists and engineers from North America, Europe, and Asia. The primary goals of the workshop were to (1) assess high-priority scientific and technical needs and (2) to evaluate options for developing and maintaining essential capabilities in marine heat flow for the U.S. scientific community.

  1. Formula Expression of Airgap Leakage flux Coefficient of Axial-Flux Permanent Magnet Motor

    Directory of Open Access Journals (Sweden)

    Yanliang Xu

    2013-07-01

    Full Text Available Airgap leakage flux coefficient is one of the main parameters which must be given ahead of time when performing initial designs or getting performance results by magnetic circuit analysis for any kinds of electrical machines. Three -dimensional finite element method (3D-FEM is the most reliable one to obtain the accurate leakage flux coefficient for axial flux permanent magnet (AFPM motor which definitely takes a much long time and is not advantageous to the motor’s initial and optimal design. By constituting the accurate lumped-parameter magnetic circuit (LPMC model and computing the resultant magnetic reluctances, the analytical formula of the leakage flux coefficient of AFPM is given which is verified by 3D-FEM and the prototyped AFPM experiment.

  2. MetaFluxNet: the management of metabolic reaction information and quantitative metabolic flux analysis.

    Science.gov (United States)

    Lee, Dong-Yup; Yun, Hongsoek; Park, Sunwon; Lee, Sang Yup

    2003-11-01

    MetaFluxNet is a program package for managing information on the metabolic reaction network and for quantitatively analyzing metabolic fluxes in an interactive and customized way. It allows users to interpret and examine metabolic behavior in response to genetic and/or environmental modifications. As a result, quantitative in silico simulations of metabolic pathways can be carried out to understand the metabolic status and to design the metabolic engineering strategies. The main features of the program include a well-developed model construction environment, user-friendly interface for metabolic flux analysis (MFA), comparative MFA of strains having different genotypes under various environmental conditions, and automated pathway layout creation. http://mbel.kaist.ac.kr/ A manual for MetaFluxNet is available as PDF file.

  3. 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.

  4. Flux variability scanning based on enforced objective flux for identifying gene amplification targets

    Science.gov (United States)

    2012-01-01

    Background In order to reduce time and efforts to develop microbial strains with better capability of producing desired bioproducts, genome-scale metabolic simulations have proven useful in identifying gene knockout and amplification targets. Constraints-based flux analysis has successfully been employed for such simulation, but is limited in its ability to properly describe the complex nature of biological systems. Gene knockout simulations are relatively straightforward to implement, simply by constraining the flux values of the target reaction to zero, but the identification of reliable gene amplification targets is rather difficult. Here, we report a new algorithm which incorporates physiological data into a model to improve the model’s prediction capabilities and to capitalize on the relationships between genes and metabolic fluxes. Results We developed an algorithm, flux variability scanning based on enforced objective flux (FVSEOF) with grouping reaction (GR) constraints, in an effort to identify gene amplification targets by considering reactions that co-carry flux values based on physiological omics data via “GR constraints”. This method scans changes in the variabilities of metabolic fluxes in response to an artificially enforced objective flux of product formation. The gene amplification targets predicted using this method were validated by comparing the predicted effects with the previous experimental results obtained for the production of shikimic acid and putrescine in Escherichia coli. Moreover, new gene amplification targets for further enhancing putrescine production were validated through experiments involving the overexpression of each identified targeted gene under condition-controlled batch cultivation. Conclusions FVSEOF with GR constraints allows identification of gene amplification targets for metabolic engineering of microbial strains in order to enhance the production of desired bioproducts. The algorithm was validated through the

  5. ENERGY AND MASS FLUX SIMULATIONS IN URBAN AREA USING THE ACASA MODEL

    Science.gov (United States)

    Marras, S.; Spano, D.; Pyles, R. D.; Falk, M.; Sirca, C.; Miglietta, F.; Snyder, R. L.; Paw U, K.

    2009-12-01

    Urban metabolism considers a city as a system and usually distinguishes between energy and material flows as its components. Population who lives in urban areas is increasing and the exchanges of water, energy and carbon into and out of cities are key to the sustainable design of cities. In this context, it is important to provide quantitative estimate of the urban metabolism components using both observations and modeling of physical flows. Today, Eddy Covariance technique and accurate models are available to simulate the energy and mass flux exchanges in urban environment with a good spatial resolution. The Advanced Canopy-Atmosphere-Soil Algorithm (ACASA) model, developed by University of California, Davis (UCD), is one of the most sophisticated models for estimating energy and mass fluxes between surface and the atmosphere. ACASA was recently modified to simulate energy and mass fluxes in urban environment. ACASA treats the surface and associated fluxes as an interconnected system The atmosphere, the urban surface and the soil are represented as a multilayer system. ACASA incorporates higher-order closure principles for turbulent statistics to predict the effects that higher-order turbulent kinetic and thermodynamic processes have on the surface microenvironment and associated fluxes of heat, moisture, momentum, and carbon. It allows counter-gradient transport that simpler models are unable to describe. Using a set of governing equations, ACASA creates vertical profiles of temperature, humidity, mean wind, and CO2 concentration. ACASA was run for the city of Florence (Italy), which is a case study of the European project “Bridge”. The simulations were compared with in situ measurements taken continuously from 2006 using an eddy covariance system located in the city centre. Different measurement periods were used to parameterize and validate the model. From the preliminary results, good agreement was obtained between simulated and observed fluxes with small

  6. Above- and belowground fluxes of CH4 from boreal shrubs and Scots pine

    Science.gov (United States)

    Halmeenmäki, Elisa; Heinonsalo, Jussi; Santalahti, Minna; Putkinen, Anuliina; Fritze, Hannu; Pihlatie, Mari

    2016-04-01

    Boreal upland forests are considered as an important sink for the greenhouse gas methane (CH4) due to CH4 oxidizing microbes in the soil. However, recent evidence suggests that vegetation can act as a significant source of CH4. Also, preliminary measurements indicate occasional emissions of CH4 above the tree canopies of a boreal forest. Nevertheless, the sources and the mechanisms of the observed CH4 emissions are still mostly unknown. Furthermore, the majority of CH4 flux studies have been conducted with the soil chamber method, thus not considering the role of the vegetation itself. We conducted a laboratory experiment to study separately the above- and belowground CH4 fluxes of bilberry (Vaccinium myrtillus), lingonberry (Vaccinium vitis-idaea), heather (Calluna vulgaris), and Scots pine (Pinus sylvestris), which were grown in microcosms. The above- and belowground fluxes of the plants were measured separately, and these fluxes were compared to fluxes of microcosms containing only humus soil. In addition to the flux measurements, we analysed the CH4 producing archaea (methanogens) and the CH4 consuming bacteria (methanotrophs) with the qPCR method to discover whether these microbes contribute to the CH4 exchange from the plant material and the soil. The results of the flux measurements indicate that the humus soil with roots of lingonberry, heather, and Scots pine consume CH4 compared to bare humus soil. Simultaneously, the shoots of heather and Scots pine emit small amounts of CH4. We did not find detectable amounts of methanogens from any of the samples, suggesting the produced CH4 could be of non-microbial origin, or produced by very small population of methanogens. Based on the first preliminary results, methanotrophs were present in all the studied plant species, and especially in high amounts in the rooted soils, thus implying that the methanotrophs could be responsible of the CH4 uptake in the root-soil systems.

  7. Surface-air mercury fluxes across Western North America: A synthesis of spatial trends and controlling variables

    Science.gov (United States)

    Eckley, Chris S.; Tate, Michael T.; Lin, Che-Jen; Gustin, Mae S.; Dent, Stephen; Eagles-Smith, Collin A.; Lutz, Michelle A; Wickland, Kimberly; Wang, Bronwen; Gray, John E.; Edwards, Grant; Krabbenhoft, David P.; Smith, David

    2016-01-01

    Mercury (Hg) emission and deposition can occur to and from soils, and are an important component of the global atmospheric Hg budget. This paper focuses on synthesizing existing surface-air Hg flux data collected throughout the Western North American region and is part of a series of geographically focused Hg synthesis projects. A database of existing Hg flux data collected using the dynamic flux chamber (DFC) approach from almost a thousand locations was created for the Western North America region. Statistical analysis was performed on the data to identify the important variables controlling Hg fluxes and to allow spatiotemporal scaling. The results indicated that most of the variability in soil-air Hg fluxes could be explained by variations in soil-Hg concentrations, solar radiation, and soil moisture. This analysis also identified that variations in DFC methodological approaches were detectable among the field studies, with the chamber material and sampling flushing flow rate influencing the magnitude of calculated emissions. The spatiotemporal scaling of soil-air Hg fluxes identified that the largest emissions occurred from irrigated agricultural landscapes in California. Vegetation was shown to have a large impact on surface-air Hg fluxes due to both a reduction in solar radiation reaching the soil as well as from direct uptake of Hg in foliage. Despite high soil Hg emissions from some forested and other heavily vegetated regions, the net ecosystem flux (soil flux + vegetation uptake) was low. Conversely, sparsely vegetated regions showed larger net ecosystem emissions, which were similar in magnitude to atmospheric Hg deposition (except for the Mediterranean California region where soil emissions were higher). The net ecosystem flux results highlight the important role of landscape characteristics in effecting the balance between Hg sequestration and (re-)emission to the atmosphere.

  8. Glacial to Holocene detrital flux and sediment provenance variations in the South Atlantic Southern Ocean

    Science.gov (United States)

    Noble, T. L.; Piotrowski, A. M.; Robinson, L. F.; McManus, J. F.

    2009-12-01

    Reconstructing input fluxes of detrital silicate material to the ocean through time provides insight into past atmospheric and ocean circulation pathways as well as the interaction between terrestrial and marine biogeochemical systems. The pathway of detrital input to the ocean can occur by a variety of mechanisms including riverine, aeolian, and ice rafting. Its provenance and flux may vary temporally. Constraining these inputs to the Southern Ocean is particularly important because productivity is limited by the lack of essential micronutrients such as Fe that are supplied by detritus. In this study we have combined 230Th-normalised detrital and mass fluxes with Pb, Nd and Sr isotope data measured on the silicate detrital phase as a tracer of sediment provenance to the Atlantic Sector of the Southern Ocean. The data presented compares the Last Glacial Maximum to the Holocene, from a transect of core sites that span the Subtropical Front in the north to the Southern Antarctic Polar Front. The latitudinal transect for the Holocene shows clearly defined sediment provinces that grade from predominately cratonic-derived-sediment at the northern sites, to a greater proportion of sediment with a mantle-derived chemical signature in the south. The northern signal is identified as silicate detritus sourced from southern Africa and a sediment component that may be derived from the North Atlantic. The sediment at the southern sites is derived primarily from the Scotia arc. The detrital flux decreases with distance away from the African continent towards Antarctica. Thus the Holocene pattern of sediment flux and provenance matches the known sediment source pathways and oceanic circulation in this region. The glacial flux and provenance is significantly different to the modern. There is no systematic pattern in the glacial detrital flux, unlike during the Holocene. In the northern sites, the detrital flux is similar to the Holocene at the shallower site (2000 mbsl), but

  9. 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.

  10. Composite Materials

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    This book deals with the mechanical and physical behavior of composites as influenced by composite geometry. "Composite Materials" provides a comprehensive introduction for researchers and students to modern composite materials research with a special emphasis on the significance of phase geometry....... The book enables the reader to a better understanding of the behavior of natural composites, improvement of such materials, and design of new materials with prescribed properties. A number of examples are presented: Special composite properties considered are stiffness, shrinkage, hygro-thermal behavior...... materials. Numerical procedures are outlined which facilitate the practical analysis of any feature considered in this book. Examples are presented which illustrate the analysis of well-known materials such as concrete, hardening cement paste, ceramics, tile, wood, impregnated and reinforced materials...

  11. Aerospace materials and material technologies

    CERN Document Server

    Wanhill, R

    2017-01-01

    This book is a comprehensive compilation of chapters on materials (both established and evolving) and material technologies that are important for aerospace systems. It considers aerospace materials in three Parts. Part I covers Metallic Materials (Mg, Al, Al-Li, Ti, aero steels, Ni, intermetallics, bronzes and Nb alloys); Part II deals with Composites (GLARE, PMCs, CMCs and Carbon based CMCs); and Part III considers Special Materials. This compilation has ensured that no important aerospace material system is ignored. Emphasis is laid in each chapter on the underlying scientific principles as well as basic and fundamental mechanisms leading to processing, characterization, property evaluation and applications. A considerable amount of materials data is compiled and presented in appendices at the end of the book. This book will be useful to students, researchers and professionals working in the domain of aerospace materials.

  12. Nano-cellulosic materials: the impact of water on their dissolution in DMAc/LiCl.

    Science.gov (United States)

    Hasani, Merima; Henniges, Ute; Idström, Alexander; Nordstierna, Lars; Westman, Gunnar; Rosenau, Thomas; Potthast, Antje

    2013-11-06

    The dissolution behaviour of disassociated cellulosic materials in N,N-dimethylacetamide/lithium chloride (DMAc/LiCl) was investigated. The parameters monitored were chromatographic elution profiles and recovered mass by means of gel permeation chromatography (GPC) with RI detection. In order to elucidate the impact of the disassembly on cellulosic fibres, comparative studies were performed with the non-disassociated cellulose counterparts. The importance of the presence of water was addressed by Karl Fischer titration and solvent exchange experiments. Morphological changes during the dissolution process were studied by scanning electron microscopy (SEM). Dissolution of fibrillated cellulosic materials is impeded compared to the non-fibrillated material. This is a consequence of the high-surface-area fibrils prone to retain high amounts of water. Dissolution behaviour of nano-crystalline cellulosic materials appeared to be source-dependent. Due to the absence of entangled networks, these materials retain only water bound at the surface of the nano-crystallites, indicative of both the exposed surface area and solubility. The small cellulose nano-particles extracted from dissolving pulp show lower solubility compared to the large NCC particles from cotton. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. FluxPro: Real time monitoring and simulation system for eddy covariance flux measurement

    Science.gov (United States)

    Kim, W.; Seo, H.; Mano, M.; Ono, K.; Miyata, A.; Yokozawa, M.

    2010-12-01

    To cope with unusual weather changes on crop cultivation in a field level, prompt and precise monitoring of photosynthesis and evapotranspiration, and those fast and reliable forecasting are indispensable. So we have developed FluxPro which is simultaneous operating system of the monitoring and the forecasting. The monitoring subsystem provides vapor and CO2 fluxes with uncertainty to understand the live condition of photosynthesis and evapotranspiration by open-path eddy covariance flux measurement (EC) system and self-developed EC tolerance analysis scheme. The forecasting subsystem serves the predicted fluxes with anomaly based on model parameter assimilation to estimate the hourly or daily water consumption and carbon assimilation during a week by multi-simulation package consisting of various models from simple to complicate. FluxPro is helpful not only to detect a critical condition of growing crop in terms of photosynthesis and evapotranspiration but also to decide time and amount of launching control for keeping those optimization condition when an unusual weather event is arisen. In our presentation, we will demonstrate the FluxPro operated at tangerine orchard in Jeju, Korea.

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

    Directory of Open Access Journals (Sweden)

    Dieuaide-Noubhani Martine

    2011-06-01

    Full Text Available Abstract Background 13C 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. Results 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. Conclusion 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

  15. Calculation of neutron flux and spectrum in the irradiation test capsule at HANARO

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Seong Woo; Cho, Man Soon; Choo, Kee Nam; Park, Sang Jun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    The irradiation test capsules were mostly used for the irradiation test in CT and OR5 irradiation hole. Since the neutron fluence is an important factor, fluence monitor(F/M)s were inserted in the irradiation test capsule in order to measure the neutron fluence of test specimen. Not only the good measurement technique but also the calculation data is necessary to accurately evaluate the neutron fluence of irradiated material. Therefore, following factors should be calculated for detailed evaluation of the neutron fluence; Neutron flux and spectrum with the position of control absorber rod(CAR), Neutron flux and spectrum at the candidate F/M irradiated position, Neutron fluence difference between F/M and specimen From this calculation data, the neutron fluence of irradiated specimen and F/M can be predicted. In this paper, the neutron flux and spectrum were calculated for the irradiation capsule. This data can be a basic data of neutron dosimetry for the irradiation test and applied to select the optimum F/M installation position and verify the neutron fluence of the specimen. The neutron flux and spectrum was calculated for irradiation test capsule. The difference of neutron flux and spectrum of the irradiation test capsule in CT and OR5 irradiation hole was observed. Also the spectral averaged cross section was calculated and applied to the fast neutron fluence evaluation. As a result of this evaluation, the good agreement between calculated and measured data was shown.

  16. NuMI Flux Predictions for NOvA and MINERvA

    Science.gov (United States)

    Aliaga Soplin, Leonidas; Nova Collaboration; Minerva Collaboration

    2017-01-01

    The determination of the neutrino flux in any conventional neutrino beam presents a challenge for the current and future short and long baseline neutrino experiments. The uncertainties associated with the production and attenuation of the hadrons in the beamline materials along with those associated with the beam optics have a big effect in the knowledge of the flux. For experiments like MINERvA and NOvA, understanding the flux is crucial since it enters directly into every neutrino-nucleus cross-section measurement. The majority of this work involves predicting the neutrino flux using dedicated hadron production measurements from hadron-nucleus collisions. The predictions at the MINERvA and NOvA near detectors are presented as well as the results of incorporating in-situ MINERvA data that can provide additional constraints. These results have been fully implemented in MINERvA and they are currently use for its cross-section analysis. The implementation for NoVA is underway. The procedure and conclusions of this work will have a big impact on future hadron production experiments and on determining the flux for the upcoming DUNE experiment.

  17. Effects of Soil Water on Soil Surface CO2 Fluxes and the Carbon Budget of a Deciduous Forest

    Science.gov (United States)

    Wilson, T. B.; Meyers, T. P.; Heuer, M.

    2007-12-01

    The CO2 flux from the soil surface is an important component of the carbon budget in a forest stand. The soil surface CO2 may contribute about 20 percent of the photosynthesis uptake by the forest with the remainder coming from the atmosphere. Since such a large fraction of the total CO2 flux above the forest canopy may originate in the soil, the contribution of soil surface CO2 flux must therefore be considered in using field measurements of CO2 fluxes to evaluate models for predicting the components of photosynthesis. The CO2 flux at the floor of a deciduous forest seems to depend on soil temperature, soil water content, amount of litter, and the photosynthesis capacity of the forest. An important way to understand these factors is to use fast response and accurate instrument to measure soil CO2 fluxes. We used a prototype soil chamber to measure soil CO2 fluxes at two locations in an oak forest in the NOAA-ATDD GEWEX flux tower network in TN, and the results from the measurement were used to evaluate the performance of a soil-plant-atmosphere model important as a gap- filling tool. Soil surface CO2 flux is the result of largely respiration by the soil biomass consisting of plant roots and dead plant materials. The respiration in vegetation environments depends on the capacity and types of vegetation, as well as on the mineralization of the organic matter by soil microbial activity, which provides nutrients for plant growth and development. In our case of the deciduous forest with large litter cover at floor below the canopy, CO2 flux may be produced by chemical reaction between rainwater and the top organic soil layer. During and immediately after rainfall, the CO2 dissolved in rainwater seems to be released from the warm soil relative to the rainwater. Similarly, CO2 may be released from the soil when rainwater displaces gas in the soil pore space. This physical interaction was observed at two flux tower sites in the oak forest reservation in Oak Ridge, TN. The

  18. Magnetic Flux Compression Concept for Nuclear Pulse Propulsion and Power

    Science.gov (United States)

    Litchford, Ronald J.

    2000-01-01

    fusion micro-bursts with reasonable levels of input energy is an equally challenging scientific problem. It remains to be seen, however, whether an effective ignition driver can be developed which meets the requirements for practical spaceflight application (namely high power density, compactness, low weight, and low cost). In this paper, system level performance and design issues are examined including generator performance, magnetic flux compression processes, magnetic diffusion processes, high temperature superconductor (HTSC) material properties, plasmadynamic processes, detonation plasma expansion processes, magnetohydrodynamic instabilities, magnetic nozzle performance, and thrust production performance. Representative generator performance calculations based on a simplified skin layer formulation are presented as well as the results of exploratory small-scale laboratory experiments on magnetic flux diffusion in HTSC materials. In addition, planned follow-on scientific feasibility experiments are described which utilize high explosive detonations and high energy gas discharges to simulate the plasma conditions associated with thermonuclear micro-detonations.

  19. Flux Accretion and Coronal Mass Ejection Dynamics

    Science.gov (United States)

    Welsch, Brian

    2017-08-01

    Coronal mass ejections (CMEs) are the primary drivers of severe space weather disturbances in the heliosphere. The equations of ideal magnetohydrodynamics (MHD) have been used to model the onset and, in some cases, the subsequent acceleration of ejections. Both observations and numerical modeling, however, suggest that magnetic reconnection likely plays a major role in most, if not all, fast CMEs. Here, we theoretically investigate the dynamical effects of accretion of magnetic flux onto a rising ejection by reconnection involving the ejection's background field. This reconnection alters the magnetic structure of the ejection and its environment, thereby modifying forces acting during the eruption, generically leading to faster acceleration of the CME. Our ultimate aim is to characterize changes in CME acceleration in terms of observable properties of magnetic reconnection, such as the amount of reconnected flux, deduced from observations of flare ribbons and photospheric magnetic fields.

  20. 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.

  1. 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.

  2. High flux diffractometers on reactor neutron sources

    Science.gov (United States)

    Hewat, Alan W.

    2006-11-01

    Continuous neutron sources such as reactors can deliver a very high time-averaged flux to the sample using a relatively wide band of wavelengths, while still retaining good resolution. For example, the D20 diffractometer at ILL Grenoble, the world's highest flux neutron powder machine, can collect complete patterns at 100 ms intervals, and this has been important for the real time study of explosive SHS reactions. New very large 2D detectors, such as those recently installed on D2B and D19 at ILL, are up to an order of magnitude larger than previous designs, and will provide unmatched speed of data collection from very small samples, opening up new scientific perspectives for powder and single crystal diffraction. We will discuss future reactor based diffractometers designed for rapid data collection from small samples in special environments.

  3. Soft Supersymmetry Breaking in KKLT Flux Compactification

    CERN Document Server

    Choi, Kiwoon; Nilles, Hans Peter; Olechowski, Marek; Choi, Kiwoon; Falkowski, Adam; Nilles, Hans Peter; Olechowski, Marek

    2005-01-01

    We examine the structure of soft supersymmetry breaking terms in KKLT models of flux compactification with low energy supersymmetry. Moduli are stabilized by fluxes and nonperturbative dynamics while a de Sitter vacuum is obtained by adding supersymmetry breaking anti-branes. We discuss the characteristic pattern of mass scales in such a set-up as well as some features of 4D N=1 supergravity breakdown by anti-branes. Anomaly mediation is found to always give an important contribution and one can easily arrange for flavor-independent soft terms. In its most attractive realization, the modulus mediation is comparable to the anomaly mediation, yielding a quite distinctive sparticle spectrum. In addition, the axion component of the modulus/dilaton superfield dynamically cancels the relative CP phase between the contributions of anomaly and modulus mediation, thereby avoiding dangerous SUSY CP violation.

  4. Magnetic flux reconstruction methods for shaped tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Tsui, Chi-Wa [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    1993-12-01

    The use of a variational method permits the Grad-Shafranov (GS) equation to be solved by reducing the problem of solving the 2D non-linear partial differential equation to the problem of minimizing a function of several variables. This high speed algorithm approximately solves the GS equation given a parameterization of the plasma boundary and the current profile (p` and FF` functions). The author treats the current profile parameters as unknowns. The goal is to reconstruct the internal magnetic flux surfaces of a tokamak plasma and the toroidal current density profile from the external magnetic measurements. This is a classic problem of inverse equilibrium determination. The current profile parameters can be evaluated by several different matching procedures. Matching of magnetic flux and field at the probe locations using the Biot-Savart law and magnetic Green`s function provides a robust method of magnetic reconstruction. The matching of poloidal magnetic field on the plasma surface provides a unique method of identifying the plasma current profile. However, the power of this method is greatly compromised by the experimental errors of the magnetic signals. The Casing Principle provides a very fast way to evaluate the plasma contribution to the magnetic signals. It has the potential of being a fast matching method. The performance of this method is hindered by the accuracy of the poloidal magnetic field computed from the equilibrium solver. A flux reconstruction package has been implemented which integrates a vacuum field solver using a filament model for the plasma, a multi-layer perception neural network as an interface, and the volume integration of plasma current density using Green`s functions as a matching method for the current profile parameters. The flux reconstruction package is applied to compare with the ASEQ and EFIT data. The results are promising.

  5. 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.

  6. 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

  7. Parametric amplification by coupled flux qubits

    OpenAIRE

    Rehak, M.; Neilinger, P.; Grajcar, M.; Oelsner, G.; Huebner, U.; Il'ichev, E.; Meyer, H. -G.

    2014-01-01

    We report the 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 measured gain of about 20 dB. We argue, that this arrangement represents a unit cell which can be straightforwardly extended to a quasi on...

  8. 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.

  9. Understanding fluxes as media for directed synthesis: in situ local structure of molten potassium polysulfides.

    Science.gov (United States)

    Shoemaker, Daniel P; Chung, Duck Young; Mitchell, J F; Bray, Travis H; Soderholm, L; Chupas, Peter J; Kanatzidis, Mercouri G

    2012-06-06

    Rational exploratory synthesis of new materials requires routes to discover novel phases and systematic methods to tailor their structures and properties. Synthetic reactions in molten fluxes have proven to be an excellent route to new inorganic materials because they promote diffusion and can serve as an additional reactant, but little is known about the mechanisms of compound formation, crystal precipitation, or behavior of fluxes themselves at conditions relevant to synthesis. In this study we examine the properties of a salt flux system that has proven extremely fertile for growth of new materials: the potassium polysulfides spanning K(2)S(3) and K(2)S(5), which melt between 302 and 206 °C. We present in situ Raman spectroscopy of melts between K(2)S(3) and K(2)S(5) and find strong coupling between n in K(2)S(n) and the molten local structure, implying that the S(n)(2-) chains in the crystalline state are mirrored in the melt. In any reactive flux system, K(2)S(n) included, a signature of changing species in the melt implies that their evolution during a reaction can be characterized and eventually controlled for selective formation of compounds. We use in situ X-ray total scattering to obtain the pair distribution function of molten K(2)S(5) and model the length of S(n)(2-) chains in the melt using reverse Monte Carlo simulations. Combining in situ Raman and total scattering provides a path to understanding the behavior of reactive media and should be broadly applied for more informed, targeted synthesis of compounds in a wide variety of inorganic fluxes.

  10. Stochastic flux freezing and magnetic dynamo.

    Science.gov (United States)

    Eyink, Gregory L

    2011-05-01

    Magnetic flux conservation in turbulent plasmas at high magnetic Reynolds numbers is argued neither to hold in the conventional sense nor to be entirely broken, but instead to be valid in a statistical sense associated to the "spontaneous stochasticity" of Lagrangian particle trajectories. The latter phenomenon is due to the explosive separation of particles undergoing turbulent Richardson diffusion, which leads to a breakdown of Laplacian determinism for classical dynamics. Empirical evidence is presented for spontaneous stochasticity, including numerical results. A Lagrangian path-integral approach is then exploited to establish stochastic flux freezing for resistive hydromagnetic equations and to argue, based on the properties of Richardson diffusion, that flux conservation must remain stochastic at infinite magnetic Reynolds number. An important application of these results is the kinematic, fluctuation dynamo in nonhelical, incompressible turbulence at magnetic Prandtl number (Pr(m)) equal to unity. Numerical results on the Lagrangian dynamo mechanisms by a stochastic particle method demonstrate a strong similarity between the Pr(m)=1 and 0 dynamos. Stochasticity of field-line motion is an essential ingredient of both. Finally, some consequences for nonlinear magnetohydrodynamic turbulence, dynamo, and reconnection are briefly considered. © 2011 American Physical Society

  11. 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

  12. Robustness of metabolic networks: Flux balance analysis

    Science.gov (United States)

    Jeong, Hawoong

    2005-03-01

    Biological systems are unimaginably complex, yet also highly robust to genetic perturbations on all levels of organization. For example, the cellular metabolism of the bacterium E. coli maintains its homeostasis, often with little or no effect on the biomass yield under a considerable portion of single gene knockouts. To address the interplay between the robustness of the final biomass yield and the underlying mechanisms in the intracellular metabolism, we identify the set of intracellular metabolites of which presences are essential for the cellular- level viability via flux balance analysis. These essential metabolites exhibit the quite different characteristics both in the topological and physiological aspects of the participating reactions, compared with the case for the non-essential ones. Most importantly, it is revealed that in viable case, production and consumption rates of each essential metabolite acquire their robustness responding to the genetic perturbations, by actively reorganizing the reaction fluxes for the ultimate robustness of the biomass yield. We also find that there is strong correlation between essentiality and flux fluctuation of metabolite under the gene deletion purturbations.

  13. Metal fluxes in the Mersey Narrows

    Directory of Open Access Journals (Sweden)

    J. A. Cole

    2001-01-01

    Full Text Available Surveys of the Mersey estuary in north-west England were undertaken near the mouth of the estuary in the region known as the Mersey Narrows. Tidal fluxes of suspended and dissolved matter, particularly heavy metals, through the Mersey Narrows were investigated. This paper gives results of conducting four intensive cross-sectional surveys of the Narrows, during which currents, salinities, turbidity and water samples were obtained systematically at numerous positions, throughout selected tidal cycles. Over 300 water samples per survey were analysed to yield suspended and dissolved concentrations of the elements As, Cd, Cr, Cu, Hg, Ni, Pb and Zn, at all states of the tide. Suspended solids, concentrations and salinities were also measured. Suspended particulates account for the majority of each element present, except for cadmium, which was present in roughly equal dissolved and suspended fractions. From the tidal current and water quality data, calculations were made of hour-by-hour fluxes of each component, to show the detailed ebb and flow of heavy metals and the net tidal transport of each component. Although some differences between landward transport on the flood tide and seaward transport on the ebb were not significant, the more definite results consistently showed a seawards net transport. For spring tides of high tidal range, there was an indication of an opposite tendency, reducing the seawards transport or even reversing it, for certain suspended components. Keywords: Mersey estuary, surveys, tidal flux, dissolved metals, particulate metals, salinity, suspended particulate matter, suspended solids

  14. 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.

  15. Gaseous Shielding Gas Additives as Flux Substitute for TIG Arc Brazing

    Directory of Open Access Journals (Sweden)

    Uwe Reisgen

    2015-09-01

    Full Text Available Abstract Brazing is one of the key technologies in the field of joining of metal components. To improve the wetting of brazing material and work-piece surface, it is often required to fall back on the use of flux. The application of these substances requires accuracy and is often connected with considerable expenditure and it is, just as the removal of flux residues, often an additional working step which has to be carried out manually. Within the framework of a DFG research project it has been investigated to which degree gaseous substances as addition to the shielding gas may replace conventional flux in TIG arc brazing. To this end, investigations have been carried out using different combinations of base and filler materials. Mainly monosilane as a gaseous flux substitute has been added in low concentrations to the shielding gas volume flow. The resulting brazed joints have been quantified with regard to their geometry, their fusion conditions and their chemical compositions. These qualities were then correlated and evaluated with the provided quantity of monosilane in order to identify dependencies.

  16. 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...

  17. 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...

  18. 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...

  19. 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.

  20. 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...

  1. 3D-Printed Detector Band for Magnetic Off-Plane Flux Measurements in Laminated Machine Cores.

    Science.gov (United States)

    Shilyashki, Georgi; Pfützner, Helmut; Palkovits, Martin; Windischhofer, Andreas; Giefing, Markus

    2017-12-19

    Laminated soft magnetic cores of transformers, rotating machines etc. may exhibit complex 3D flux distributions with pronounced normal fluxes (off-plane fluxes), perpendicular to the plane of magnetization. As recent research activities have shown, detections of off-plane fluxes tend to be essential for the optimization of core performances aiming at a reduction of core losses and of audible noise. Conventional sensors for off-plane flux measurements tend to be either of high thickness, influencing the measured fluxes significantly, or require laborious preparations. In the current work, thin novel detector bands for effective and simple off-plane flux detections in laminated machine cores were manufactured. They are printed in an automatic way by an in-house developed 3D/2D assembler. The latter enables a unique combination of conductive and non-conductive materials. The detector bands were effectively tested in the interior of a two-package, three-phase model transformer core. They proved to be mechanically resilient, even for strong clamping of the core.

  2. 3D-Printed Detector Band for Magnetic Off-Plane Flux Measurements in Laminated Machine Cores

    Science.gov (United States)

    Pfützner, Helmut; Palkovits, Martin; Windischhofer, Andreas; Giefing, Markus

    2017-01-01

    Laminated soft magnetic cores of transformers, rotating machines etc. may exhibit complex 3D flux distributions with pronounced normal fluxes (off-plane fluxes), perpendicular to the plane of magnetization. As recent research activities have shown, detections of off-plane fluxes tend to be essential for the optimization of core performances aiming at a reduction of core losses and of audible noise. Conventional sensors for off-plane flux measurements tend to be either of high thickness, influencing the measured fluxes significantly, or require laborious preparations. In the current work, thin novel detector bands for effective and simple off-plane flux detections in laminated machine cores were manufactured. They are printed in an automatic way by an in-house developed 3D/2D assembler. The latter enables a unique combination of conductive and non-conductive materials. The detector bands were effectively tested in the interior of a two-package, three-phase model transformer core. They proved to be mechanically resilient, even for strong clamping of the core. PMID:29257063

  3. Nano Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jin, In Ju; Lee, Ik Mo; Kwon, Yeung Gu; and others

    2006-02-15

    This book introduces background of nano science such as summary, plenty room at the bottom, access way to nano technique, nanoparticles using bottom-up method which are a marvel of nature, and modern alchemy : chemical synthesis of artificial nano structure, understanding of quantum mechanics, STM/AFM, nano metal powder, ceramic nanoparticles, nano structure film, manufacture of nanoparticles using reverse micelle method, carbon nano tube, sol-gel material, nano energy material, nano catalyst nano bio material technology and spintronics.

  4. Composite Materials

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    This book deals with the mechanical and physical behavior of composites as influenced by composite geometry. "Composite Materials" provides a comprehensive introduction for researchers and students to modern composite materials research with a special emphasis on the significance of phase geometry....... The book enables the reader to a better understanding of the behavior of natural composites, improvement of such materials, and design of new materials with prescribed properties. A number of examples are presented: Special composite properties considered are stiffness, shrinkage, hygro-thermal behavior...

  5. Dopant type and/or concentration selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Dishman, J.L.

    1987-03-10

    A method is described of selectively photochemically dry etching a first semiconductor material of a given composition in the presence of a second semiconductor material which is of a composition different from the first material. The second material is not substantially etched during the method which comprises: subjecting both materials to the same photon flux of an energy greater than their respective direct bandgaps and to the same gaseous chemical etchant under conditions where the etchant would be ineffective for chemical etching of either material where the photons not present, the conditions also being such that the resultant electronic structure of the first semiconductor material under the photon flux is sufficient for the first material to undergo substantial photochemical etching under the conditions. The conditions also are such that the resultant electronic structure of the second semiconductor material under the photon flux is not sufficient for the second material to undergo substantial photochemical etching under the conditions.

  6. Micrometeorological flux measurements at a coastal site

    Science.gov (United States)

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

    2014-05-01

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

  7. Aspects of six-dimensional flux compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Dierigl, Markus

    2017-08-15

    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{sup 2} and one of its orbifolds T{sup 2}/Z{sub 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{sup 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

  8. Linking Precipitation Patterns to Stream Nitrogen Fluxes

    Science.gov (United States)

    Reid, J. P.; Finlay, J. C.

    2011-12-01

    Precipitation is becoming less-frequent but more-intense across most of the world. These changes to the timing and intensity of precipitation should affect ecological processes - such as primary productivity, soil decomposition, nitrification, and watershed nitrogen (N) retention - that are functions of soil moisture. Drying and rewetting cycles are known to reduce plant uptake and microbial immobilization of N, while temporarily increasing nitrification rates, thus reducing the effectiveness of N retention mechanisms. Because the timing of intense rainfall events is more likely to align with reduced nitrogen retention capacity, watershed N losses should increase. We hypothesized that the lag between precipitation and nitrate flux is shortest for low-frequency, high-intensity rainfall, and shortest in watersheds with high hydraulic conductivity. We used long-term records of precipitation, stream discharge and nitrate concentrations to analyze the relationship between precipitation and stream nitrate flux using wavelet decomposition, cross-wavelet transforms and wavelet coherence. The analyzed streams are located across an urban to rural gradient in the Baltimore area. We found little or no synchronization between precipitation and stream nitrate flux in the forested reference watershed at annual time scales. However, annual precipitation and nitrate flux in urban and suburban watersheds were significantly synchronized. Furthermore, nitrate flux consistently lagged behind precipitation in these urbanized watersheds. The differences between forested and suburban/urban watersheds could be a consequence of differences in impervious surface area and drainage mechanisms including storm drains. These results suggest that urbanization changes the scales of precipitation patterns that nitrate export is sensitive to. For example, annual nitrate export consistently lags behind precipitation at Baisman's Run, with just 20% suburban land cover in an otherwise forested watershed

  9. 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 ...

  10. 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

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

    Indian Academy of Sciences (India)

    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 spatial resolution.

  12. Latent heat sink in soil heat flux measurements

    Science.gov (United States)

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

  13. Tuning the Gap of a Superconducting Flux Qubit

    NARCIS (Netherlands)

    Paauw, F.G.; Fedorov, A.; Harmans, C.J.P.M.; Mooij, J.E.

    2009-01-01

    We experimentally demonstrate the in situ tunability of the minimum energy splitting (gap) of a superconducting flux qubit by means of an additional flux loop. Pulses applied via a local control line allow us to tune the gap over a range of several GHz on a nanosecond time scale. The strong flux

  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. 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 ...

  16. 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.

  17. Synthesis and stabilization of oxide-based colloidal suspensions in organic media: application in the preparation of hybrids organic-inorganic materials for very high laser damage threshold coatings; Synthese et stabilisation de suspensions colloidales d'oxydes en milieu organique: application a la preparation de materiaux hybrides organiques-inorganiques pour des revetements a tres haute tenue au flux laser

    Energy Technology Data Exchange (ETDEWEB)

    Marchet, N.

    2008-02-15

    Multilayer coatings are widely used in optic and particular in the field of high power laser on the components of laser chains. The development of a highly reflective coating with a laser damage resistance requires the fine-tuning of a multilayer stack constituted by a succession alternated by materials with low and high refractive index. In order to limit the number of layers in the stack, refractive indexes must be optimized. To do it, an original approach consists in synthesizing new organic-inorganic hybrid materials satisfying the criteria of laser damage resistance and optimized refractive index. These hybrid materials are constituted by nano-particles of metal oxides synthesized by sol-gel process and dispersed in an organic polymer with high laser damage threshold. Nevertheless, this composite system requires returning both compatible phases between them by chemical grafting of alc-oxy-silanes or carboxylic acids. We showed that it was so possible to disperse in a homogeneous way these functionalized nano-particles in non-polar, aprotic solvent containing solubilized organic polymers, to obtain time-stable nano-composite solutions. From these organic-inorganic hybrid solutions, thin films with optical quality and high laser damage threshold were obtained. These promising results have permitted to realize highly reflective stacks, constituted by 7 pairs with optical properties in agreement with the theoretical models and high laser damage threshold. (author)

  18. 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.

  19. From COS ecosystem fluxes to GPP: integrating soil, branch and ecosystem fluxes.

    Science.gov (United States)

    Kooijmans, L.; Maseyk, K. S.; Vesala, T.; Mammarella, I.; Baker, I. T.; Seibt, U.; Sun, W.; Aalto, J.; Franchin, A.; Kolari, P.; Keskinen, H.; Levula, J.; Chen, H.

    2016-12-01

    The close coupling of Carbonyl Sulfide (COS) and CO2 due to a similar uptake pathway into plant stomata makes COS a promising new tracer that can potentially be used to partition the Net Ecosystem Exchange into gross primary production (GPP) and respiration. Although ecosystem-scale measurements have been made at several sites, the contribution of different ecosystem components to the total COS budget is often unknown. Besides that, the average Leaf Relative Uptake (LRU) ratio needs to be better determined to accurately translate COS ecosystem fluxes into GPP estimates when the simple linear correlation between GPP estimates and COS plant uptake is used. We performed two campaigns in the summer of 2015 and 2016 at the SMEAR II site in Hyytiälä, Finland to provide better constrained COS flux data for boreal forests. A combination of COS measurements were made during both years, i.e. atmospheric profile concentrations up to 125 m, eddy-covariance fluxes and soil chamber fluxes. In addition to these, branch chamber measurements were done in 2016 in an attempt to observe the LRU throughout the whole season. The LRU ratio shows an exponential correlation with photosynthetic active radiation (PAR) but is constant for PAR levels above 500 µmol m-2 s-1. Mid-day LRU values are 1.0 (aspen) and 1.5 (pine). The correlation between LRU and PAR can be explained by the fact that COS is hydrolyzed with the presence of the enzyme carbonic anhydrase, and is not light dependent, whereas the photosynthetic uptake of CO2 is. We observed nighttime fluxes on the order of 25-30 % of the daily maximum COS uptake. Soils are a small sink of COS and contribute to 3 % of the total ecosystem COS flux during daytime. In a comparison between observed and simulated fluxes from the Simple Biosphere (SiB) model, the modelled COS and CO2 ecosystem fluxes are on average 40 % smaller than the observed fluxes, however, the Ecosystem Relative Uptake (ERU) ratios are identical at a value of 1.9 ± 0

  20. 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.

  1. Material Systems

    DEFF Research Database (Denmark)

    Jensen, Mads Brath; Mortensen, Henrik Rubæk; Mullins, Michael

    2009-01-01

    This paper describes and reflects upon the results of an investigative project which explores the setting up of a material system - a parametric and generative assembly consisting of and taking into consideration material properties, manufacturing constraints and geometric behavior. The project...

  2. Ferroic Materials

    Indian Academy of Sciences (India)

    reasonably nontechnical language. The vast application potential of ferroic materials is highlighted. Introduction. Materials possess symmetry, and sometimes .... tive sign, and even of variable magnitude. Thus the magnetisation is no more a single-valued function of the applied field. This behaviour, brought about by the ...

  3. Biogeochemical flux and phytoplankton succession: A year-long sediment trap record in the Australian sector of the Subantarctic Zone

    Science.gov (United States)

    Wilks, Jessica V.; Rigual-Hernández, Andrés S.; Trull, Thomas W.; Bray, Stephen G.; Flores, José-Abel; Armand, Leanne K.

    2017-03-01

    The Subantarctic Zone (SAZ) plays a crucial role in global carbon cycling as a significant sink for atmospheric CO2. In the Australian sector, the SAZ exports large quantities of organic carbon from the surface ocean, despite lower algal biomass accumulation in surface waters than other Southern Ocean sectors. We present the first analysis of diatom and coccolithophore assemblages and seasonality, as well as the first annual quantification of bulk organic components of captured material at the base of the mixed layer (500 m depth) in the SAZ. Sediment traps were moored in the SAZ southwest of Tasmania as part of the long-term SAZ Project for one year (September 2003 to September 2004). Annual mass flux at 500 m and 2000 m was composed mainly of calcium carbonate, while biogenic silica made up on average <10% of material captured in the traps. Organic carbon flux was estimated at 1.1 g m-2 y-1 at 500 m, close to the estimated global mean carbon flux. Low diatom fluxes and high fluxes of coccoliths were consistent with low biogenic silica and high calcium carbonate fluxes, respectively. Diatoms and coccoliths were identified to species level. Diatom and coccolithophore sinking assemblages reflected some seasonal ecological succession. A theoretical scheme of diatom succession in live assemblages is compared to successional patterns presented in sediment traps. This study provides a unique, direct measurement of the biogeochemical fluxes and their main biological carbon vectors just below the winter mixed layer depth at which effective sequestration of carbon occurs. Comparison of these results with previous sediment trap deployments at the same site at deeper depths (i.e. 1000, 2000 and 3800 m) documents the changes particle fluxes experience in the lower ;twilight zone; where biological processes and remineralisation of carbon reduce the efficiency of carbon sequestration.

  4. Aluminium surface morphology behaviour under high-flux helium ion bombardment

    Science.gov (United States)

    Girka, O.; Bizyukov, O.; Bogatyrenko, S.; Bizyukov, I.

    2017-08-01

    Samples of aluminium with purity 99.99% wt are irradiated with helium ion beam under ITER-like conditions using FALCON ion source. Aluminium is used as the surrogate material for plasma-material interaction studies. Typical parameters during steady-state exposure are the following: helium ion flux is 2-4 × 1022 m-2 s-1, heat flux is above 1 MW m-2, average ion energy is of 2 keV, and the ion fluence is well above 1027 m-2. Investigation of the surface morphology with SEM shows the formation of the cone-like structures, which develop with fluence increasing. Surface features suddenly disappear at the fluence of 1.06 × 1027 m-2 and then start to grow again. Further fluence increase with step-by-step surface diagnostics shows periodical character of the surface structures growth and degradation.

  5. Glazed porcelain tiles produced by the dry route: fluxing raw; Gres porcelanico esmaltado producido por via seca: materias primas fundentes

    Energy Technology Data Exchange (ETDEWEB)

    Melchiades, B. G.; Dos Santos, L. R.; Nastri, S.; Boschi, A. O.

    2012-07-01

    Fluxing agents are particularly important in porcelain tile compositions because this type of ceramic tile requires high volumes of vitreous phases during firing to eliminate open porosity. The volume and viscosity of the vitreous phases formed during firing control the densification process and thus determine the firing temperature and pyro plastic deformation. The fluxing agents commonly employed in porcelain tile compositions are feldspars, pettishly (used in Brazil) and nepheline. These raw materials are water-insoluble, which makes them particularly suitable for compositions of traditional porcelain tile produced by the wet route. However, a large group of water-soluble raw materials also have a good potential to act as fluxing agents and could be used in dry route processes. In this context, the purpose of this work was to determine the fluxing potential of water-soluble or partially water-soluble raw materials in a porcelain tile composition. The effectiveness of several borates, i.e., colemanite, ulexine, hydroboracite, as well as sodium carbonate, was tested in a comparative study. The results of this study indicate that small additions of these fluxing agents suffice to greatly reduce the firing temperature without causing high pyro plastic deformation of the bodies. The best results were obtained in compositions containing hydroboracite. This finding is especially relevant for the creation of alternative compositions of porcelain tiles produced by the dry route. Dry route processing is currently the focus of a great deal of interest due to environmental and economic issues. (Author)

  6. Composite Materials

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    . The book enables the reader to a better understanding of the behavior of natural composites, improvement of such materials, and design of new materials with prescribed properties. A number of examples are presented: Special composite properties considered are stiffness, shrinkage, hygro-thermal behavior......, viscoelastic behavior, and internal stress states. Other physical properties considered are thermal and electrical conductivities, diffusion coefficients, dielectric constants and magnetic permeability. Special attention is given to the effect of pore shape on the mechanical and physical behavior of porous...... materials. Numerical procedures are outlined which facilitate the practical analysis of any feature considered in this book. Examples are presented which illustrate the analysis of well-known materials such as concrete, hardening cement paste, ceramics, tile, wood, impregnated and reinforced materials...

  7. Material Programming

    DEFF Research Database (Denmark)

    Vallgårda, Anna; Boer, Laurens; Tsaknaki, Vasiliki

    2017-01-01

    , and color, but additionally being capable of sensing, actuating, and computing. Indeed, computers will not be things in and by themselves, but embedded into the materials that make up our surroundings. This also means that the way we interact with computers and the way we program them, will change....... Consequently we ask what the practice of programming and giving form to such materials would be like? How would we be able to familiarize ourselves with the dynamics of these materials and their different combinations of cause and effect? Which tools would we need and what would they look like? Will we program...... these computational composites through external computers and then transfer the code them, or will the programming happen closer to the materials? In this feature we outline a new research program that floats between imagined futures and the development of a material programming practice....

  8. Periodontal materials.

    Science.gov (United States)

    Darby, I

    2011-06-01

    Periodontics is more associated with debridement of periodontal pockets and not generally thought of as using dental materials in the treatment of patients. However, the last 30 years have seen the development of materials used in regeneration of the periodontal tissues following periodontal disease, guided tissue regeneration, and the use of these materials in bone regeneration more recently, guided bone regeneration. The materials used include bone grafts and membranes, but also growth factors and cells-based therapies. This review provides an overview of the materials currently used and looks at contemporary research with a view to what may be used in the future. It also looks at the clinical effectiveness of these regenerative therapies with an emphasis on what is available in Australia. © 2011 Australian Dental Association.

  9. Composite material

    Science.gov (United States)

    Hutchens, Stacy A [Knoxville, TN; Woodward, Jonathan [Solihull, GB; Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN

    2012-02-07

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  10. Bioresponsive materials

    Science.gov (United States)

    Lu, Yue; Aimetti, Alex A.; Langer, Robert; Gu, Zhen

    2017-01-01

    'Smart' bioresponsive materials that are sensitive to biological signals or to pathological abnormalities, and interact with or are actuated by them, are appealing therapeutic platforms for the development of next-generation precision medications. Armed with a better understanding of various biologically responsive mechanisms, researchers have made innovations in the areas of materials chemistry, biomolecular engineering, pharmaceutical science, and micro- and nanofabrication to develop bioresponsive materials for a range of applications, including controlled drug delivery, diagnostics, tissue engineering and biomedical devices. This Review highlights recent advances in the design of smart materials capable of responding to the physiological environment, to biomarkers and to biological particulates. Key design principles, challenges and future directions, including clinical translation, of bioresponsive materials are also discussed.

  11. Touching Materiality

    DEFF Research Database (Denmark)

    Rasmussen, Lisa Rosén

    2012-01-01

    . Drawing on anthropological writings, the article argues that the objects of materiality are part of important but non-verbalised memories of schooling. The Dutch philosopher Eelco Runia’s notions of presence and metonymy are incorporated as tools for approaching objects of materiality in memory studies.......Dripping ink pens, colourful paint on skin, vegetables pots on a school roof. In interviews with three generations of former school pupils, memories of material objects bore a relation to everyday school life in the past. Interwoven, these objects entered the memorising processes, taking...... the interviewer and interviewee beyond an exclusively linguistic understanding of memory. This article analyses how the shifting objects of materiality in personal and generational school memories connects to material as well as sensuous experiences of everyday school life and its complex processes of learning...

  12. 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

  13. Rigid levitation, flux pinning, thermal depinning and fluctuation in high-Tc superconductors

    Science.gov (United States)

    Brandt, E. H.

    1991-01-01

    Here, the author shows that the strong velocity-independent frictional force on a levitating superconductor and on any type-II superconductor moving in a homogeneous magnetic field is caused by pinning and depinning of the magnetic flux lines in its interior. Levitation may thus be used to investigate the pinning properties of a superconductor, and friction in a superconductor bearing may be minimized by choosing appropriate materials and geometries.

  14. Finite Element Analysis of Nondestructive Testing by Leakage Flux Method Using Remanent Magnetism

    OpenAIRE

    坪井, 始; 瀬島, 紀夫; 田中, 始男; ツボイ, ハジメ; セシマ, ノリオ; タナカ, モトオ; Hajime, TSUBOI; Norio, SESHIMA; Motoo, TANAKA

    2003-01-01

    Magnetic field analysis of nondestructive testing using remanent magnetism was performed by using two-dimensional finite element method. A leakage flux method using remanent magnetism is applied to magnetic material as nondestructive testing method. The remanent magnetism is approximated by equivalent magnetizing electric current. And we assumed that the remanent magnetization is in proportion to the magnetization in the magnetizing process. Formulation of the finite element method using magn...

  15. Contaminant Flux Reduction Barriers for Managing Difficult-to-Treat Source Zones in Unconsolidated Media

    Science.gov (United States)

    2017-06-20

    with Other Remedial Options ........ 56  v ACRONYMS AND ABBREVIATIONS bgs Below ground surface CaCl2 Calcium chloride cis-1,2-DCE cis-1,2...for a one acre site). Project Tasks  Task 1: Research Flux Reduction Materials: Several novel silica gel/vegetable oil- formulations were...enhanced reductive dechlorination zone when the competing electron acceptors are diverted. One research paper (Newell and Aziz, 2004) estimate a

  16. 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....

  17. Spatially averaged heat flux and convergence measurements at the ARM regional flux experiment

    Energy Technology Data Exchange (ETDEWEB)

    Porch, W.; Barnes, F.; Buchwald, M.; Clements, W.; Cooper, D.; Hoard, D. (Los Alamos National Lab., NM (United States)); Doran, C.; Hubbe, J.; Shaw, W. (Pacific Northwest Lab., Richland, WA (United States)); Coulter, R.; Martin, T. (Argonne National Lab., IL (United States)); Kunkel, K. (Illinois State Water Survey, Champaign, IL (United States))

    1991-01-01

    Cloud formation and its relation to climate change is the greatest weakness in current numerical climate models. Surface heat flux in some cases causes clouds to form and in other to dissipate and the differences between these cases are subtle enough to make parameterization difficult in a numerical model. One of the goals of the DOE Atmospheric Radiation Measurement program is to make long term measurements at representative sites to improve radiation and cloud formation parameterization. This paper compares spatially averaged optical measurements of heat flux and convergence with a goal of determining how point measurements of heat fluxes scale up to the larger scale used for climate modeling. It was found that the various optical techniques used in this paper compared well with each other and with independent measurements. These results add confidence that spatially averaging optical techniques can be applied to transform point measurements to the larger scales needed for mesoscale and climate modeling. 10 refs., 6 figs. (MHB)

  18. Effects of flux concentrations and sintering temperature on dental porcelain

    Science.gov (United States)

    Ghose, Polash; Gafur, Md. Abdul; Das, Sujan Kumar; Ranjan Chakraborty, Shyamal; Mohsin, Md.; Deb, Arun Kumar; Rakibul Qadir, Md.

    2014-02-01

    In this study, samples of dental porcelain bodies have been made by using the materials collected from selected deposits employing different mixing proportions of clay, quartz and feldspar. Dental porcelain ceramics have been successfully fabricated by using the sintering technique together with some Na2CO3 additive. The dental porcelain powder has been pressed into pellets at first and subsequently sintered at 700, 800, 900, 1000 and 1100 °C for 2 h. The physical and mechanical properties of the prepared samples have been investigated. The sintering behavior of the fired samples has been evaluated by bulk density, linear shrinkage, water absorption and apparent porosity measurements. This study includes the evaluation of the Vickers's microhardness by microhardness tester. Phase analysis and microstructural study have been performed by XRD and optical microscope respectively. Optical properties have been investigated using UV-visible spectroscopy. Influence of firing conditions on leucite formation, densification and microstructural development of the sintered samples has been investigated. It has been found that the choice of sintering temperature is one of the key factors in controlling leucite crystallization in dental porcelain ceramics. It has also been found that the flux concentration of material and the effect of temperature on preparation of dental porcelain contribute to the firing shrinkage and hardness, which has been found to increase with the increase of treatment temperature.

  19. Seasonal and interannual variability in the flux of planktic foraminifera in the Humboldt Current System off central Chile (30°S)

    Science.gov (United States)

    Marchant, Margarita; Hebbeln, Dierk; Giglio, Susana; Coloma, Cecilia; González, Humberto E.

    2004-10-01

    Seasonal and interannual changes in the flux of planktic foraminifers were studied in the Humboldt Current System off Coquimbo, Chile (30°S; 73°15'W), using material collected by time series sediment traps located at 2300 m water depth and 100 nautical miles from the coast. The almost continuous record spans 6 years (1993-1998) with a temporal resolution of 6-13 days. The seasonal flux pattern of planktic foraminifers was marked by high fluxes during austral late winter-early summer (August-January) and low fluxes during the fall-early winter period (March-July). Five species contributed ˜90% of the total flux of planktic foraminifers: Globigerina bulloides, Neogloboquadrina incompta, N. pachyderma, N. dutertrei, and Globigerinella calida. Stable oxygen isotope variability in foraminifer shells appears to be driven by seasonal changes in surface seawater temperature; isotope data of G. bulloides and N. incompta (>212 and 150-212 μm size classes) suggest that water-column stratification dominates during the low-flux period and mixing during the high-flux period. The strong 1997-1998 El Niño event had only a limited impact on the planktic foraminifer flux. The most significant El Niño-related signal was a remarkable increase in the flux and abundance of species that, under normal conditions, only accounted for total planktic foraminiferal assemblage.

  20. What the flux? Deriving empirical estimates of riverine Mo fluxes over Earth history

    Science.gov (United States)

    Romaniello, S. J.; Ostrander, C. M.; Johnson, A.; Planavsky, N.; Anbar, A. D.

    2016-12-01

    Molybdenum (Mo) is a key micronutrient in the marine nitrogen cycle and thus plays an important role in regulating global marine primary productivity and biogeochemistry. At present, Mo is the most abundant transition metal in seawater, despite being one of the least abundant transition metals in crustal rocks. This counterintuitive behavior is the result of the high solubility and mobile nature of the molybdate anion under oxidizing conditions. However, previous studies have pointed out that the oxidative weathering flux of Mo to the ocean was likely much lower under Archean conditions, and that when coupled with reduced solubility of Mo in anoxic seawater, portions of the ocean may have been Mo starved. With few exceptions, riverine fluxes of elements have been only poorly constrained over geologic time. In the absence of strong empirical constraints, fluxes are either imagined to have been similar to today, or radically different, depending primarily on the chemistry of the element and model implored by the authors. Based on large variations of Mo concentrations in shales, several authors have invoked models where riverine Mo fluxes vary in response to atmospheric O2 availability but it has been difficult to provide independent constraints to support or refute these models. Here we demonstrate a novel approach for constraining riverine Mo fluxes from the Archean to present by independently estimating the seawater Mo inventory from Mo/TOC ratios and the Mo residence time from Mo isotope ratios. At steady state, the riverine flux is then the ratio of these parameters. Surprisingly, despite strong secular evolution of seawater Mo concentrations and residence time, this approach suggests the overall rate of Mo supply to the ocean was probably relatively constant within one order of magnitude over most of Earth history. This result provides new insights into both the processes controlling Mo availability to the oceans and, more broadly, the controls on oxidative

  1. Observational biases in flux magnification measurements

    Science.gov (United States)

    Hildebrandt, H.

    2016-02-01

    Flux magnification is an interesting complement to shear-based lensing measurements, especially at high redshift where sources are harder to resolve. One measures either changes in the source density (magnification bias) or in the shape of the flux distribution (e.g. magnitude shift). The interpretation of these measurements relies on theoretical estimates of how the observables change under magnification. Here, we present simulations to create multiband photometric mock catalogues of Lyman-break galaxies in a CFHTLenS (Canada France Hawaii Telescope Lensing Survey)-like survey that include several observational effects that can change these relations, making simple theoretical estimates unusable. In particular, we show how the magnification bias can be affected by photometric noise, colour selection, and dust extinction. We find that a simple measurement of the slope of the number-counts is not sufficient for the precise interpretation of virtually all observations of magnification bias. We also explore how sensitive the shift in the mean magnitude of a source sample in different photometric bands is to magnification including the same observational effects. Again we find significant deviations from simple analytical estimates. We also discover a wavelength-dependence of the magnitude-shift effect when applied to a colour-selected noisy source sample. Such an effect can mimic the reddening by dust in the lens. It has to be disentangled from the dust extinction before the magnitude shift/colour-excess can be used to measure the distribution of either dark matter or extragalactic dust. Using simulations like the ones presented here these observational effects can be studied and eventually removed from observations making precise measurements of flux magnification possible.

  2. 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.

  3. 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.

  4. Greenhouse gas fluxes over Central European grasslands

    Science.gov (United States)

    Hörtnagl, L. J.; Bahn, M.; Barthel, M.; Eugster, W.; Klumpp, K.; Ladreiter-Knauss, T.; Merbold, L.; Wohlfahrt, G.; Buchmann, N. C.

    2014-12-01

    The uptake of carbon dioxide (CO2) by grassland ecosystems can be offset by the concurrent emission of the greenhouse gases methane (CH4) and nitrous oxide (N2O) in terms of CO2-equivalents. As a consequence, CH4 and N2O emissions can contribute to an increase of the global warming potential (GWP) of the respective study site. For a full assessment of the climatic impact of grassland ecosystems it is therefore necessary to quantify fluxes of these two compounds in combination with CO2 exchange. Since agricultural management practices and land use change at a given site can have a strong impact on annual CH4 and N2O budgets, both compounds are a frequent topic of discussion when planning GHG mitigation strategies.Here we present an overview of the GHG exchange of eight managed Central European grassland sites along a gradient of elevation and land use intensity. Fluxes of the three major GHGs CO2, CH4 and N2O were quantified using the eddy covariance or chamber technique. The grasslands differed with regard to the amount of fertilizer input, frequency of cuts and grazing duration and intensity, ranging from more intensively managed to very lightly managed and abandoned grassland. In this presentation we focus on time periods when measurements of all three compounds were available for all sites. We investigate common features among observed CH4 and N2O exchange patterns at the different grassland sites in relation to management activities and concurrently measured biotic / abiotic parameters. In addition, we evaluate the impact of CH4 and N2O fluxes on the annual GWP of field sites for which long-term measurements are available.

  5. 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.

  6. Flux Cancelation: The Key to Solar Eruptions

    Science.gov (United States)

    Panesar, Navdeep K.; Sterling, Alphonse; Moore, Ronald; Chakrapani, Prithi; Innes, Davina; Schmit, Don; Tiwari, Sanjiv

    2017-01-01

    Solar coronal jets are magnetically channeled eruptions that occur in all types of solar environments (e.g. active regions, quiet-Sun regions and coronal holes). Recent studies show that coronal jets are driven by the eruption of small-scare filaments (minifilaments). Once the eruption is underway magnetic reconnection evidently makes the jet spire and the bright emission in the jet base. However, the triggering mechanism of these eruptions and the formation mechanism of the pre-jet minifilaments are still open questions. In this talk, mainly using SDOAIA and SDOHIM data, first I will address the question: what triggers the jet-driving minifilament eruptions in different solar environments (coronal holes, quiet regions, active regions)? Then I will talk about the magnetic field evolution that produces the pre-jet minifilaments. By examining pre-jet evolutionary changes in line-of-sight HMI magnetograms while examining concurrent EUV images of coronal and transition-region emission, we find clear evidence that flux cancelation is the main process that builds pre-jet minifilaments, and is also the main process that triggers the eruptions. I will also present results from our ongoing work indicating that jet-driving minifilament eruptions are analogous to larger-scare filament eruptions that make flares and CMEs. We find that persistent flux cancellation at the neutral line of large-scale filaments often triggers their eruptions. From our observations we infer that flux cancelation is the fundamental process from the buildup and triggering of solar eruptions of all sizes.

  7. Experimental assessment of the performance of ablative heat shield materials from plasma wind tunnel testing

    Science.gov (United States)

    Löhle, S.; Hermann, T.; Zander, F.

    2017-12-01

    A method for assessing the performance of typical heat shield materials is presented in this paper. Three different material samples, the DLR material uc(Zuram), the Airbus material uc(Asterm) and the carbon preform uc(Calcarb) were tested in the IRS plasma wind tunnel PWK1 at the same nominal condition. State of the art diagnostic tools, i.e., surface temperature with pyrometry and thermography and boundary layer optical emission spectroscopy were completed by photogrammetric surface recession measurements. These data allow the assessment of the net heat flux for each material. The analysis shows that the three materials each have a different effect on heat flux mitigation with ASTERM showing the largest reduction in surface heat flux. The effect of pyrolysis and blowing is clearly observed and the heat flux reduction can be determined from an energy balance.

  8. Nitrous oxide fluxes from tree stems of temperate forests

    Science.gov (United States)

    Wen, Yuan; Corre, Marife D.; Rachow, Christine; Veldkamp, Edzo

    2017-04-01

    Although trees are recognized as conduits of soil-generated N2O, little is known about N2O fluxes from mature trees under field conditions and thier contributions to total forest N2O fluxes. Here, we quantified in situ stem N2O fluxes from mature alder trees on poorly-drained soil and mature beech and spruce trees on well-drained soils in Solling, Germany from March to October 2015. Soil N2O fluxes, soil N2O concentrations at 40-cm depth, and soil and climatic variables known to influence N2O fluxes were also measured concurrently with the stem N2O fluxes. Alder, beech and spruce consistently emitted N2O via stems and all displayed higher emission rates in summer than in spring and in autumn. Stem N2O fluxes from alder stand were higher than those from beech and spruce stands (P emissions in upland trees. Stem N2O fluxes represented 8-11% of the total (soil + stem) N2O fluxes in the spruce and beech stands whereas in the alder stand, with its large soil N2O emission, stem emission contributed only 1% of the total flux. Our results suggest that the relative contribution of tree-mediated N2O fluxes is more important in upland trees than in wetland trees.

  9. Variable Quaternary chemical weathering fluxes and imbalances in marine geochemical budgets.

    Science.gov (United States)

    Vance, Derek; Teagle, Damon A H; Foster, Gavin L

    2009-03-26

    Rivers are the dominant source of many elements and isotopes to the ocean. But this input from the continents is not balanced by the loss of the elements and isotopes through hydrothermal and sedimentary exchange with the oceanic crust, or by temporal changes in the marine inventory for elements that are demonstrably not in steady state. To resolve the problem of the observed imbalance in marine geochemical budgets, attention has been focused on uncertainties in the hydrothermal and sedimentary fluxes. In recent Earth history, temporally dynamic chemical weathering fluxes from the continents are an inevitable consequence of periodic glaciations. Chemical weathering rates on modern Earth are likely to remain far from equilibrium owing to the physical production of finely ground material at glacial terminations that acts as a fertile substrate for chemical weathering. Here we explore the implications of temporal changes in the riverine chemical weathering flux for oceanic geochemical budgets. We contend that the riverine flux obtained from observations of modern rivers is broadly accurate, but not representative of timescales appropriate for elements with oceanic residence longer than Quaternary glacial-interglacial cycles. We suggest that the pulse of rapid chemical weathering initiated at the last deglaciation has not yet decayed away and that weathering rates remain about two to three times the average for an entire late Quaternary glacial cycle. Taking into account the effect of the suggested non-steady-state process on the silicate weathering flux helps to reconcile the modelled marine strontium isotope budget with available data. Overall, we conclude that consideration of the temporal variability in riverine fluxes largely ameliorates long-standing problems with chemical and isotopic mass balances in the ocean.

  10. Parasitic Momentum Flux in the Tokamak Core

    CERN Document Server

    Stoltzfus-Dueck, T

    2016-01-01

    A geometrical correction to the E x B drift causes an outward flux of cocurrent momentum whenever electrostatic potential energy is transferred to ion parallel flows. The robust symmetry breaking follows from the free energy flow in phase space and does not depend on any assumed linear eigenmode structure, acting both for axisymmetric fluctuations (such as geodesic acoustic modes) as well as more general nonaxisymmetric fluctuations. The resulting rotation peaking is countercurrent and scales as electron temperature over plasma current. This peaking mechanism can only act when fluctuations are low-frequency enough to excite ion parallel flows, which may explain some recent experimental observations related to rotation reversals.

  11. 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

  12. Geometric Algebra Techniques in Flux Compactifications

    Directory of Open Access Journals (Sweden)

    Calin Iuliu Lazaroiu

    2016-01-01

    Full Text Available We study “constrained generalized Killing (spinors,” 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.

  13. 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...... 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...

  14. 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...

  15. Planck intermediate results. LII. Planet flux densities

    Science.gov (United States)

    Planck Collaboration; Akrami, Y.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S.; Benabed, K.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Carron, J.; Chiang, H. C.; Colombo, L. P. L.; Comis, B.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Di Valentino, E.; Dickinson, C.; Diego, J. M.; Doré, O.; Ducout, A.; Dupac, X.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Fantaye, Y.; Finelli, F.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frolov, A.; Galeotta, S.; Galli, S.; Ganga, K.; Génova-Santos, R. T.; Gerbino, M.; González-Nuevo, J.; Górski, K. M.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Helou, G.; Henrot-Versillé, S.; Herranz, D.; Hivon, E.; Jaffe, A. H.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kiiveri, K.; Kim, J.; Kisner, T. S.; Krachmalnicoff, N.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Le Jeune, M.; Lellouch, E.; Levrier, F.; Liguori, M.; Lilje, P. B.; Lindholm, V.; López-Caniego, M.; Ma, Y.-Z.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Maris, M.; Martin, P. G.; Martínez-González, E.; Matarrese, S.; Mauri, N.; McEwen, J. D.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Molinari, D.; Moneti, A.; Montier, L.; Moreno, R.; Morgante, G.; Natoli, P.; Oxborrow, C. A.; Paoletti, D.; Partridge, B.; Patanchon, G.; Patrizii, L.; Perdereau, O.; Piacentini, F.; Plaszczynski, S.; Polenta, G.; Rachen, J. P.; Racine, B.; Reinecke, M.; Remazeilles, M.; Renzi, A.; Rocha, G.; Romelli, E.; Rosset, C.; Roudier, G.; Rubiño-Martín, J. A.; Ruiz-Granados, B.; Salvati, L.; Sandri, M.; Savelainen, M.; Scott, D.; Sirri, G.; Spencer, L. D.; Suur-Uski, A.-S.; Tauber, J. A.; Tavagnacco, D.; Tenti, M.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Trombetti, T.; Valiviita, J.; Van Tent, F.; Vielva, P.; Villa, F.; Wehus, I. K.; Zacchei, A.

    2017-11-01

    Measurements of flux density are described for five planets, Mars, Jupiter, Saturn, Uranus, and Neptune, across the six Planck High Frequency Instrument frequency bands (100-857 GHz) and these are then compared with models and existing data. In our analysis, we have also included estimates of the brightness of Jupiter and Saturn at the three frequencies of the Planck Low Frequency Instrument (30, 44, and 70 GHz). The results provide constraints on the intrinsic brightness and the brightness time-variability of these planets. The majority of the planet flux density estimates are limited by systematic errors, but still yield better than 1% measurements in many cases. Applying data from Planck HFI, the Wilkinson Microwave Anisotropy Probe (WMAP), and the Atacama Cosmology Telescope (ACT) to a model that incorporates contributions from Saturn's rings to the planet's total flux density suggests a best fit value for the spectral index of Saturn's ring system of βring = 2.30 ± 0.03 over the 30-1000 GHz frequency range. Estimates of the polarization amplitude of the planets have also been made in the four bands that have polarization-sensitive detectors (100-353 GHz); this analysis provides a 95% confidence level upper limit on Mars's polarization of 1.8, 1.7, 1.2, and 1.7% at 100, 143, 217, and 353 GHz, respectively. The average ratio between the Planck-HFI measurements and the adopted model predictions for all five planets (excluding Jupiter observations for 353 GHz) is 1.004, 1.002, 1.021, and 1.033 for 100, 143, 217, and 353 GHz, respectively. Model predictions for planet thermodynamic temperatures are therefore consistent with the absolute calibration of Planck-HFI detectors at about the three-percent level. We compare our measurements with published results from recent cosmic microwave background experiments. In particular, we observe that the flux densities measured by Planck HFI and WMAP agree to within 2%. These results allow experiments operating in the mm

  16. Fluctuation theorems for continuously monitored quantum fluxes.

    Science.gov (United States)

    Campisi, Michele; Talkner, Peter; Hänggi, Peter

    2010-10-01

    It is shown that quantum fluctuation theorems remain unaffected if measurements of any kind and number of observables are performed during the action of a force protocol. That is, although the backward and forward probabilities entering the fluctuation theorems are both altered by these measurements, their ratio remains unchanged. This observation allows us to describe the measurement of fluxes through interfaces and, in this way, to bridge the gap between the current theory, based on only two measurements performed at the beginning and end of the protocol, and experiments that are based on continuous monitoring.

  17. Parametric amplification by coupled flux qubits

    Science.gov (United States)

    Rehák, M.; Neilinger, P.; Grajcar, M.; Oelsner, G.; Hübner, U.; Il'ichev, E.; Meyer, H.-G.

    2014-04-01

    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 × 10-3) 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.

  18. CO2 flux from Javanese mud volcanism

    OpenAIRE

    Quei?er, M.; Burton, M.; 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 r...

  19. Diffusion piecewise homogenization via flux discontinuity factors

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Richard; Zmijarevic, Igor, E-mail: richard.sanchez@cea.fr, E-mail: igor.zmijarevic@cea.fr [Commissariat a l' Energie Atomique et aux Energies Alternatives, Service d' Etudes de Reacteurs et de Mathematiques Appliquees, Gif-sur-Yvette cedex (France)

    2011-07-01

    We analyze the calculation of flux discontinuity factors (FDFs) for use with piecewise subdomain assembly homogenization. These coefficients depend on the numerical mesh used to compute the diffusion problem. When the mesh has a single degree of freedom on subdomain interfaces the solution is unique and can be computed independently per subdomain. For all other cases we have implemented an iterative calculation for the FDFs. Our numerical results show that there is no solution to this nonlinear problem but that the iterative algorithm converges towards FDFs values that reproduce subdomains reaction rates with a relatively high precision. In our test we have included both the GET and black-box FDFs. (author)

  20. Greenhouse Gas Fluxes from Peatland Pools

    Science.gov (United States)

    Turner, E.; Baird, A. J.; Billett, M. F.; Chapman, P. J.; Dinsmore, K. J.; Holden, J.

    2015-12-01

    Peatlands contain around one third of the global soil carbon (C) stock. Understanding the processes in peatland C cycling, and in particular those involved in the release of the greenhouse gases (GHGs) CO2 and CH4 to the atmosphere, is a current research priority. Natural open-water pools are a common feature of many peatlands, and previous research suggests pools can be strong sources of atmospheric GHGs, particularly CH4, and thus have the potential to play an important role in global radiative forcing. The area of open-water in peatlands is rapidly expanding in a warming Arctic (e.g. Walter et al., 2007) while artificially created pools are becoming more commonplace in the recent drive to restore the hydrological functioning of drained peatlands by blocking ditches. We present the results of >2 years of comprehensive field monitoring from pool complexes in the Flow Country of northern Scotland, the largest expanse (c.4000 km2) of blanket bog in Europe. Concentrations and fluxes of CO2 and CH4 are presented from 12 intensively monitored pools and the adjacent terrestrial surface. We examined both natural (n = 6) and artificial (n = 6) pools, which allowed us to quantify how pools created during restoration compare to undisturbed sites. C and hydrology budgets were determined for the study pools and the adjacent terrestrial surface. Dissolved concentrations of GHGs ranged from 0.08-4.68 mg CO2-C L-1 and 0.01-731 µg CH4-C L-1 in natural pools, and 0.29-10.38 mg CO2-C L-1 and 0.04-239 µg CH4-C L-1 in artificial pools. GHG fluxes from natural pool surfaces ranged between -2.47-653 mg CH4 m-2 d-1 and -31.7-14.8 g CO2 m-2 d-1. Artificial pool GHG fluxes were -8.19-581 mg CH4 m-2 d-1 and -7.66-34.9 g CO2 m-2 d-1. We provide more accurate GHG budgets for peatlands with natural pool complexes by considering their relative importance at the landscape-scale, and outline the potential effect on GHG fluxes when creating artificial pools during peatland restoration

  1. Flux growth of BPO 4 crystals

    Science.gov (United States)

    Li, Zhihua; Wu, Yicheng; Fu, Peizhen; Pan, Shilie; Chen, Chuangtian

    2004-10-01

    Single crystals of BPO4 with sizes up to 15×10×12 mm3 were grown by top-seeded solution growth method using Li2O-Li4P2O7 as fluxes. The components volatilized from the melt were characterized by the method of X-ray powder diffraction. The defects of grown crystals have also been investigated. The measured ultraviolet cutoff edge of BPO4 was about 130 nm. Its density was 2.82 g/cm3 determined using drainage method.

  2. Generation of the Ultracold Muonic Hydrogen Flux

    Energy Technology Data Exchange (ETDEWEB)

    Bystritsky, V. M. [Joint Institute for Nuclear Research (Russian Federation); Adamczak, A. [Institute of Nuclear Physics (Poland); Beer, G. A. [University of Victoria (Canada); Filipowicz, M. [Institute of Physics and Nuclear Techniques (Poland); Fujiwara, M. C. [University of Tokyo (Japan); Huber, T. M. [Gustavus Adolphus College (United States); Jacot-Guillarmod, R. [Universite de Fribourg (Switzerland); Kammel, P. [University of Illinois at Urbana-Champaign (United States); Kim, S. K. [Jeonbuk National University (Korea, Republic of); Knowles, P. [Universite de Fribourg (Switzerland); Kunselman, A. R. [University of Wyoming (United States); Maier, M. [University of Victoria (Canada); Markushin, V. E. [Paul Scherrer Institute (Switzerland); Marshall, G. M. [TRIUMF (Canada); Mulhauser, F. [Universite de Fribourg (Switzerland); Olin, A. [University of Victoria (Canada); Petitjean, C. [Paul Scherrer Institute (Switzerland); Porcelli, T. A. [University of Northen British Columbia (Canada); Stolupin, V. A. [Joint Institute for Nuclear Research (Russian Federation); Wozniak, J. [Institute of Physics and Nuclear Techniques (Poland)

    2001-12-15

    We present the study of {mu}p atom scattering in solid hydrogen. Anomalously large emission of E{sub p{mu}{<=}1}.9 meV {mu}p's from a solid H{sub 2} layer was observed for the first time. This three times greater {mu}p atom yield is due to non-elastic phonon scattering. As a result, it becomes possible to generate an ultracold flux of {mu}p atoms. The recent calculations of the total and differential cross sections agree with all experimental results of {mu}p atom scattering in solid H{sub 2}.

  3. Utopian Materialities

    DEFF Research Database (Denmark)

    Elgaard-Jensen, Torben

    2004-01-01

    In various ways, this paper makes the counter-intuitive claim that the utopian and the material are thoroughlyinterdependent, rather than worlds apart. First, through a reading of Thomas More's Utopia, it is argued thatUtopia is the product of particular kinds of relations, rather than merely...... to its persuasive image of being the office of the future.The notion that utopia is achieved through material arrangements is finally related to the analysis of facts andfictions in ANT. It is argued, that even though Utopias are neither fact nor fiction, they are both material andeffective...

  4. Simulation of Underground Muon Flux with Application to Muon Tomography

    Science.gov (United States)

    Yamaoka, J. A. K.; Bonneville, A.; Flygare, J.; Lintereur, A.; Kouzes, R.

    2015-12-01

    Muon tomography uses highly energetic muons, produced by cosmic rays interacting within the upper atmosphere, to image dense materials. Like x-rays, an image can be constructed from the negative of the absorbed (or scattered) muons. Unlike x-rays, these muons can penetrate thousands of meters of earth. Muon tomography has been shown to be useful across a wide range of applications (such as imaging of the interior of volcanoes and cargo containers). This work estimates the sensitivity of muon tomography for various underground applications. We use simulations to estimate the change in flux as well as the spatial resolution when imaging static objects, such as mine shafts, and dynamic objects, such as a CO2 reservoir filling over time. We present a framework where we import ground density data from other sources, such as wells, gravity and seismic data, to generate an expected muon flux distribution at specified underground locations. This information can further be fed into a detector simulation to estimate a final experimental sensitivity. There are many applications of this method. We explore its use to image underground nuclear test sites, both the deformation from the explosion as well as the supporting infrastructure (access tunnels and shafts). We also made estimates for imaging a CO2 sequestration site similar to Futuregen 2.0 in Illinois and for imaging magma chambers beneath the Cascade Range volcanoes. This work may also be useful to basic science, such as underground dark matter experiments, where increasing experimental sensitivity requires, amongst other factors, a precise knowledge of the muon background.

  5. Quantifying organic matter fluxes in an era of wetland instability

    Science.gov (United States)

    Ganju, N. K.; Kroeger, K. D.

    2016-02-01

    In an era of sea-level rise and altered sediment supply, unstable tidal wetlands may disintegrate and become a significant source of particulate organic matter and carbon to the coastal ocean. Quantifying the fluxes of particulate matter over tidal, seasonal, and annual timescales is critical for evaluating the ecosystem services provided by tidal wetlands. Using high-temporal resolution measurements over a 2.5 mo period we calculated suspended-sediment, organic matter, and particulate organic carbon (POC) fluxes in two tidal wetland systems adjacent to Chesapeake Bay. One system is characterized by several decades of instability and marsh collapse, while the other has remained stable over the same period. We collected >100 water samples over several tidal cycles and obtained a linear relationship between organic and mineral content. A subset of those samples was processed for carbon concentration and isotopic characterization; both systems displayed a consistent carbon fraction of 40% of organic material. Isotopic analysis revealed a consistent d13C of -25 at both sites, consistent with a C3 plant source (likely Schoenoplectus). Ultimately the unstable wetland exported POC at a rate of 48 g/m2/y while the stable wetland imported 21 g/m2/y. While these rates are comparable to carbon burial estimates (48-105 g/m2/y), systemic erosion will continue to reduce the carbon sequestration potential of wetland systems while releasing POC to the coastal zone. Future assessments of wetland carbon sequestration potential must consider both wetland stability and export of POC from eroding systems.

  6. Comparison of regional and ecosystem CO2 fluxes

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Søgaard, Henrik; Batchvarova, Ekaterina

    2009-01-01

    A budget method to derive the regional surface flux of CO2 from the evolution of the boundary layer is presented and applied. The necessary input for the method can be deduced from a combination of vertical profile measurements of CO2 concentrations by i.e. an airplane, successive radio......-soundings and standard measurements of the CO2 concentration near the ground. The method was used to derive the regional flux of CO2 over an agricultural site at Zealand in Denmark during an experiment on 12–13 June 2006. The regional fluxes of CO2 represent a combination of agricultural and forest surface conditions....... It was found that the regional flux of CO2 in broad terms follows the behavior of the flux of CO2 at the agricultural (grassland) and the deciduous forest station. The regional flux is comparable not only in size but also in the diurnal (daytime) cycle of CO2 fluxes at the two stations....

  7. Experimental Realization of Extreme Heat Flux Concentration with Easy-to-Make Thermal Metamaterials

    Science.gov (United States)

    Chen, Fei; Yuan Lei, Dang

    2015-06-01

    The ability to harvest thermal energy and manipulate heat fluxes has recently attracted a great deal of research interest because this is critical to achieve efficient solar-to-thermal energy conversion in the technology of concentrated solar thermal collectors. Thermal metamaterials with engineered thermal conduction are often utilized to control the diffusive heat flow in ways otherwise not possible with naturally occurring materials. In this work, we adopt the transformation thermodynamics approach to design an annular fan-shaped thermal metamaterial which is capable of guiding heat fluxes and concentrating thermal energy to the central region of the metamaterial device without disturbing the temperature profile outside the structure - a fascinating and unique feature impossibly achieved with homogeneous materials. In experiment, this rationally-designed metamaterial structure demonstrates extreme heat flux compression from both line-shaped and point thermal sources with measured concentration efficiency up to 83.1%, providing the first experimental realization of our recent theoretical prediction (T. Han et al., Energy Environ. Sci., 2013, 6, 3537-3541). These unprecedented results may open up new possibilities for engineering thermal materials with desired properties that can be used for dramatically enhancing the efficiency of the existing solar thermal collectors.

  8. New materials for welding and surfacing

    Science.gov (United States)

    Kozyrev, N. A.; Galevsky, G. V.; Kryukov, R. E.; Titova, D. A.; Shurupov, V. M.

    2016-09-01

    The paper provides description of research into the influence of new materials and technologies on quality parameters of welds and deposited metal carried out in the research and production centre “Welding processes and technologies”. New welding technologies of tanks for northern conditions are considered, as well as technologies of submerged arc welding involving fluxing agents AN - 348, AN - 60, AN - 67, OK.10.71 and carbon-fluorine containing additives; new flux cored wires and surfacing technologies, teaching programs and a trainer for welders are designed.

  9. Laboratory Study of Methane Flux from Acid Sulphate Soil in South Kalimantan

    Science.gov (United States)

    Annisa, W.; Cahyana, D.; Syahbuddin, H.; Rachman, A.

    2017-06-01

    Addition of organic matter in waterlogged conditions will enhance methanogenesis process that produces greenhouse gases. Fresh organic material is considered reactive because it contains carbons that is subject to decompose, therefore, when it exposed to acid sulphate soil, both in natural condition (aeration required) and intensive (aeration not required) will lower the value of redox potential. This experiment aimed to determine the flux of methane (CH4) from various locally available organic materials applied to acid sulphate soil. The experiment was arranged in factorial design with two factors. The first factor was the source of organic matter, i.e. fresh rice straw, fresh purun, fresh cattle manure, composted rice straw, composted purun and composted cattle manure, and control. The second factor was the management of organic matter i.e. placed on the soil surface with no tillage and mixed with soil during tillage. The results showed that application of fresh organic matter into inundated acid sulphate soil increased CH4 fluxes up to 23.78 µg CH4 g1 d1 which was higher than from composted organic matter (4.327 µg CH4.g1.d1). Methane flux due to organic matter management was significantly negatively (p=0.001) correlated with soil redox potential (Eh) with R2 of - 0.76. Organic matter placed on the soil surface with no tillage produced methane flux ranged from 0.33 to 20.78 g CH4 g1 d1, which was lower than methane flux produced from organic matter mixed with soil during tillage (0.38 to 27.27 g CH4 g1 d1). Composting organic matter before application and mixing them with the soil through tillage are highly recommended to reduce greenhouse gas emissions from cultivated acid sulphate soils.

  10. Study on roles of anaplerotic pathways in glutamate overproduction of Corynebacterium glutamicum by metabolic flux analysis

    Directory of Open Access Journals (Sweden)

    Shioya Suteaki

    2007-06-01

    Full Text Available Abstract Background Corynebacterium glutamicum has several anaplerotic pathways (anaplerosis, which are essential for the productions of amino acids, such as lysine and glutamate. It is still not clear how flux changes in anaplerotic pathways happen when glutamate production is induced by triggers, such as biotin depletion and the addition of the detergent material, Tween 40. In this study, we quantitatively analyzed which anaplerotic pathway flux most markedly changes the glutamate overproduction induced by Tween 40 addition. Results We performed a metabolic flux analysis (MFA with [1-13C]- and [U-13C]-labeled glucose in the glutamate production phase of C. glutamicum, based on the analysis of the time courses of 13C incorporation into proteinogenic amino acids by gas chromatography-mass spectrometry (GC-MS. The flux from phosphoenolpyruvate (PEP to oxaloacetate (Oxa catalyzed by phosphoenolpyruvate carboxylase (PEPc was active in the growth phase not producing glutamate, whereas that from pyruvate to Oxa catalyzed by pyruvate carboxylase (Pc was inactive. In the glutamate overproduction phase induced by the addition of the detergent material Tween 40, the reaction catalyzed by Pc also became active in addition to the reaction catalyzed by PEPc. Conclusion It was clarified by a quantitative 13C MFA that the reaction catalyzed by Pc is most markedly increased, whereas other fluxes of PEPc and PEPck remain constant in the glutamate overproduction induced by Tween 40. This result is consistent with the previous results obtained in a comparative study on the glutamate productions of genetically recombinant Pc- and PEPc-overexpressing strains. The importance of a specific reaction in an anaplerotic pathway was elucidated at a metabolic level by MFA.

  11. The use of submerged-arc welding flux slag as raw material for the fabrication of multiple-use mortars and bricks Uso de escória de fluxo de soldagem a arco submerso como matéria-prima para a fabricação de argamassas de múltiplo uso e tijolos

    Directory of Open Access Journals (Sweden)

    Caroline Espinosa Viana

    2009-09-01

    Full Text Available This work has as objective to analyze the recycling possible uses of the slag of welding flux (SWF in the civil construction. It was searched the liability of SWF as substitute of sand in the production of multiple-use mortars and clay for the production of ceramic bricks. SWF has origin in the submerged-arc welding (SAW, and have been used slags of the acid, neutral and basic types, according to its neutrality. Mortars have been made containing the three types of SWF and in addition a reference mortar made with sand. Physical and mineralogical characteristics of each SWF were studied, and the physical properties (consistency and density and mechanical properties (compressive and tensile strengths of the mortars were analyzed. Ceramic pieces have been made containing kaolinitic sedimentary clay up to 10 wt. % of SWF. The pieces were prepared by uniaxial pressing and fired at 950ºC. The following properties after firing were determined: linear shrinkage, water absorption, apparent porosity, apparent density, and flexural strength. The results show that for multiple-use mortars, SWF reached excellent results, being an overall substitute for sand as fine aggregate. For ceramic bricks, SWF can also be used as partial substitute for red clay. Both applications of SWF significantly contributes for the reduction of the ambient impact: on one hand, reducing the extraction of natural sand and clay, on other hand, contributing for the reduction of the risk of ground water contamination due to the inadequate disposal of the SWF.Este trabalho tem como objetivo avaliar possíveis usos para a reciclagem da escória de fluxo de soldagem (EFS na construção civil. Foi pesquisada a possibilidade do uso da EFS como substituto da areia na produção de argamassas de múltiplo-uso e substituição da argila na produção de tijolos. A EFS tem origem na soldagem a arco submerso (SAS, e foram usadas escórias dos tipos ácida, neutra e básica, conforme sua

  12. Reference Materials

    Science.gov (United States)

    Merkus, Henk G.

    Reference materials for measurement of particle size and porosity may be used for calibration or qualification of instruments or for validation of operating procedures or operators. They cover a broad range of materials. On the one hand there are the certified reference materials, for which governmental institutes have certified one or more typical size or porosity values. Then, there is a large group of reference materials from commercial companies. And on the other hand there are typical products in a given line of industry, where size or porosity values come from the analysis laboratory itself or from some round-robin test in a group of industrial laboratories. Their regular application is essential for adequate quality control of particle size and porosity measurement, as required in e.g., ISO 17025 on quality management. In relation to this, some quality requirements for certification are presented.

  13. Spatial-temporal variability in GHG fluxes and their functional interpretation in RusFluxNet

    Science.gov (United States)

    Vasenev, Ivan; Meshalkina, Julia; Sarzhanov, Dmitriy; Mazirov, Ilia; Yaroslavtsev, Alex; Komarova, Tatiana; Tikhonova, Maria

    2016-04-01

    High spatial and temporal variability is mutual feature for most modern boreal landscapes in the European Territory of Russia. This variability is result of their relatively young natural and land-use age with very complicated development stories. RusFluxNet includes a functionally-zonal set of representative natural, agricultural and urban ecosystems from the Central Forest Reserve in the north till the Central Chernozemic Reserve in the south (more than 1000 km distance). Especial attention has been traditionally given to their soil cover and land-use detailed variability, morphogenetic and functional dynamics. Central Forest Biosphere Reserve (360 km to North-West from Moscow) is the principal southern-taiga one in the European territory of Russia with long history of mature spruce ecosystem structure and dynamics investigation. Our studies (in frame of RF Governmental projects #11.G34.31.0079 and #14.120.14.4266) have been concentrated on the soil carbon stocks and GHG fluxes spatial variability and dynamics due to dominated there windthrow and fallow-forest successions. In Moscow RTSAU campus gives a good possibility to develop the ecosystem and soil monitoring of GHG fluxes in the comparable sites of urban forest, field crops and lawn ecosystems taking especial attention on their meso- and micro-relief, soil cover patterns and subsoil, vegetation and land-use technologies, temperature and moisture spatial and temporal variability. In the Central Chernozemic Biosphere Reserve and adjacent areas we do the comparative analysis of GHG fluxes and balances in the virgin and mowed meadow-steppe, forest, pasture, cropland and three types of urban ecosystems with similar subsoil and relief conditions. The carried out researches have shown not only sharp (in 2-5 times) changes in GHG ecosystem and soil fluxes and balances due to seasonal and daily microclimate variation, vegetation and crop development but their essential (in 2-4 times) spatial variability due to

  14. Propulsion materials

    Energy Technology Data Exchange (ETDEWEB)

    Wall, Edward J. [U.S. Dept. of Energy, Washington, D.C. (United States); Sullivan, Rogelio A. [U.S. Dept. of Energy, Washington, D.C. (United States); Gibbs, Jerry L. [U.S. Dept. of Energy, Washington, D.C. (United States)

    2008-01-01

    The Department of Energy’s (DOE’s) Office of Vehicle Technologies (OVT) is pleased to introduce the FY 2007 Annual Progress Report for the Propulsion Materials Research and Development Program. Together with DOE national laboratories and in partnership with private industry and universities across the United States, the program continues to engage in research and development (R&D) that provides enabling materials technology for fuel-efficient and environmentally friendly commercial and passenger vehicles.

  15. Background Material

    DEFF Research Database (Denmark)

    Zandersen, Marianne; Hyytiäinen, Kari; Saraiva, Sofia

    This document serves as a background material to the BONUS Pilot Scenario Workshop, which aims to develop harmonised regional storylines of socio-ecological futures in the Baltic Sea region in a collaborative effort together with other BONUS projects and stakeholders.......This document serves as a background material to the BONUS Pilot Scenario Workshop, which aims to develop harmonised regional storylines of socio-ecological futures in the Baltic Sea region in a collaborative effort together with other BONUS projects and stakeholders....

  16. Encountering Materiality

    DEFF Research Database (Denmark)

    Svabo, Connie

    2016-01-01

    DHT researcher Connie Svabo and artist Charlotte Grum did a joint performance presentation titled Becoming Sheep, Becoming Animal at the international conference Encountering Materiality – Transdisciplinary Conversations, held in Geneve, Schwitzerland, June 23-25 2016.......DHT researcher Connie Svabo and artist Charlotte Grum did a joint performance presentation titled Becoming Sheep, Becoming Animal at the international conference Encountering Materiality – Transdisciplinary Conversations, held in Geneve, Schwitzerland, June 23-25 2016....

  17. Polymeric Materials

    Science.gov (United States)

    2009-06-01

    Sandia)-funded programs and two approved proposals for neutron scattering time at NIST. To enable future growth, optically adaptive materials for...Nanophase Particle ( SNAP ) Coatings.” Progress in Organic Coatings, 47(3-4), 337, 2003. Jong-Beom Baek and Loon-Seng Tan, “Linear-Hyperbranched...Silicates”, Materials Research Society Symposium Proceedings, Volume Date 2004, 840( Neutron and X-Ray Scattering as Probes of Multiscale Phenomena), 57

  18. Materials informatics

    OpenAIRE

    Krishna Rajan

    2005-01-01

    Seeking structure-property relationships is an accepted paradigm in materials science, yet these relationships are often not linear, and the challenge is to seek patterns among multiple lengthscales and timescales. There is rarely a single multiscale theory or experiment that can meaningfully and accurately capture such information. In this article, we outline a process termed ‘materials informatics’ that allows one to survey complex, multiscale information in a high-throughput, statistically...

  19. Composite Materials

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    , viscoelastic behavior, and internal stress states. Other physical properties considered are thermal and electrical conductivities, diffusion coefficients, dielectric constants and magnetic permeability. Special attention is given to the effect of pore shape on the mechanical and physical behavior of porous......This book deals with the mechanical and physical behavior of composites as influenced by composite geometry. "Composite Materials" provides a comprehensive introduction for researchers and students to modern composite materials research with a special emphasis on the significance of phase geometry...

  20. Supersymmetric branes on curved spaces and fluxes

    CERN Document Server

    Triendl, Hagen

    2015-01-01

    We discuss general supersymmetric brane configurations in flux backgrounds of string and M-theory and derive a necessary condition for the worldvolume theory to be supersymmetric on a given curved manifold. This condition resembles very much the conditions found from coupling a supersymmetric field theory to off-shell supergravity but can be derived in any dimension and for up to sixteen supercharges. Apart from the topological twist, all couplings appearing in the supersymmetry condition are linked to fluxes in the bulk. We explicitly derive the condition for D3-, M2- and M5-branes, in which case the results are also useful for constructing holographic duals to the corresponding field theories. In $N=1$ setups we compare the supersymmetry conditions to those that arise by coupling the field theory to off-shell supergravity. We find that the couplings of both old and new minimal supergravity are simultaneously realized, indicating that off-shell supergravity should be coupled via the S-multiplet of 16/16 supe...

  1. Generalized non-supersymmetric flux vacua

    CERN Document Server

    Lüst, Dieter; Martucci, Luca; Tsimpis, Dimitrios

    2008-01-01

    We discuss a novel strategy to construct 4D N=0 stable flux vacua of type II string theory, based on the existence of BPS bounds for probe D-branes in some of these backgrounds. In particular, we consider compactifications where D-branes filling the 4D space-time obey the same BPS bound as they would in an N=1 compactification, while other D-branes, like those appearing as domain walls from the 4D perspective, can no longer be BPS. We construct a subfamily of such backgrounds giving rise to 4D N=0 Minkowski no-scale vacua, generalizing the well-known case of type IIB on a warped Calabi-Yau. We provide several explicit examples of these constructions, and compute quantities of phenomenological interest like flux-induced soft terms on D-branes. Our results have a natural, simple description in the language of Generalized Complex Geometry, and in particular in terms of D-brane generalized calibrations. Finally, we extend the integrability theorems for 10D supersymmetric type II backgrounds to the N=0 case and us...

  2. Extremal Black Hole and Flux Vacua Attractors

    CERN Document Server

    Bellucci, S; Kallosh, R; Marrani, A

    2007-01-01

    These lectures provide a pedagogical, introductory review of the so-called Attractor Mechanism (AM) at work in two different 4-dimensional frameworks: extremal black holes in N=2 supergravity and N=1 flux compactifications. In the first case, AM determines the stabilization of scalars at the black hole event horizon purely in terms of the electric and magnetic charges, whereas in the second context the AM is responsible for the stabilization of the universal axion-dilaton and of the (complex structure) moduli purely in terms of the RR and NSNS fluxes. Two equivalent approaches to AM, namely the so-called ``criticality conditions'' and ``New Attractor'' ones, are analyzed in detail in both frameworks, whose analogies and differences are discussed. Also a stringy analysis of both frameworks (relying on Hodge-decomposition techniques) is performed, respectively considering Type IIB compactified on $CY_{3}$ and its orientifolded version, associated with $\\frac{CY_{3}\\times T^{2}}{\\mathbb{Z}_{2}}$. Finally, recent...

  3. Auxin-driven patterning with unidirectional fluxes

    Science.gov (United States)

    Cieslak, Mikolaj; Runions, Adam; Prusinkiewicz, Przemyslaw

    2015-01-01

    The plant hormone auxin plays an essential role in the patterning of plant structures. Biological hypotheses supported by computational models suggest that auxin may fulfil this role by regulating its own transport, but the plausibility of previously proposed models has been questioned. We applied the notion of unidirectional fluxes and the formalism of Petri nets to show that the key modes of auxin-driven patterning—the formation of convergence points and the formation of canals—can be implemented by biochemically plausible networks, with the fluxes measured by dedicated tally molecules or by efflux and influx carriers themselves. Common elements of these networks include a positive feedback of auxin efflux on the allocation of membrane-bound auxin efflux carriers (PIN proteins), and a modulation of this allocation by auxin in the extracellular space. Auxin concentration in the extracellular space is the only information exchanged by the cells. Canalization patterns are produced when auxin efflux and influx act antagonistically: an increase in auxin influx or concentration in the extracellular space decreases the abundance of efflux carriers in the adjacent segment of the membrane. In contrast, convergence points emerge in networks in which auxin efflux and influx act synergistically. A change in a single reaction rate may result in a dynamic switch between these modes, suggesting plausible molecular implementations of coordinated patterning of organ initials and vascular strands predicted by the dual polarization theory. PMID:26116915

  4. Flux flattening in axion monodromy inflation

    Science.gov (United States)

    Landete, Aitor; Marchesano, Fernando; Shiu, Gary; Zoccarato, Gianluca

    2017-06-01

    String theory models of axion monodromy inflation exhibit scalar potentials which are quadratic for small values of the inflaton field and evolve to a more complicated function for large field values. Oftentimes the large field behaviour is gentler than quadratic, lowering the tensor-to-scalar ratio. This effect, known as flattening, has been observed in the string theory context through the properties of the DBI+CS D-brane action. We revisit such flattening effects in type IIB flux compactifications with mobile D7-branes, with the inflaton identified with the D7-brane position. We observe that, with a generic choice of background fluxes, flattening effects are larger than previously observed, allowing to fit these models within current experimental bounds. In particular, we compute the cosmological observables in scenarios compatible with closed-string moduli stabilisation, finding tensor-to-scalar ratios as low as r ˜ 0 .04. These are models of single field inflation in which the inflaton is much lighter than the other scalars through a mild tuning of the compactification data.

  5. Flux growth and crystal structure of pyromorphite.

    Science.gov (United States)

    Akao, A; Aoki, H; Innami, Y; Minamikata, S; Yamada, T

    1989-01-01

    Single crystals of pyromorphite, Pb5(PO4)3Cl, were grown by standard flux growth technique with excess lead chloride used as the flux. Pyromorphite was first prepared by heating an intimate mixture of lead hydrogen phosphate and lead chloride in the molar ratio 6:4 at 100 degrees C for 1 h. A mixture of 60 wt% of pyromorphite and 40 wt% of lead chloride was heated at 850 degrees C for 15 h and then cooled at the rate of 3.4 degrees C/h. Hexagonal prismatic crystals of length 1 mm were obtained. The chemical composition has close to the theoretical value. The crystal is hexagonal, space group P6(3)/m with a = 9.9981(8), c = 7.344(1) A and Z = 2. The structure was refined to R = 0.058 and Rw = 0.053 with 502 independent reflections. The structure is in principal the same as that of barium chlorapatite; the chlorine ions occupy the (0, 0, 0) position.

  6. Development of a silicone ablator for high-heat-flux and high-shear-rate condition

    Science.gov (United States)

    Campbell, R. A.; Ramseyer, J. A.; Huntress, A.

    1972-01-01

    A silicone material was developed which gives suitable ablative protection in the high heat flux, high shear environments encountered in severe reentry applications, such as nose cones for ballistic vehicles and protection of leading edges or other critical areas of a vehicle. In addition, the ease of handling, low application cost, and room temperature cure make such a silicon material suitable nozzles for the large rockets necessary for vehicle launching. The development of this product is traced from the selection of suitable polymers through the choice of fillers and the finalization of filler loadings.

  7. Fracture mode for porous materials under laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Uglov, A.A.; Grebennikov, V.A.

    Specific features of the fracture processes of porous materials prepared by the methods of powder metallurgy, laser radiation (LR) are considered. Qualitatively analysed is the role of separate factors (flux density, porosity and others), exerting influence on zone parameters of LR interaction on porous materials. The comparison of the results of the process analysis with experimental data for nickel and molybdenum is given.

  8. Plasma-material interaction under simulated disruption conditions

    Energy Technology Data Exchange (ETDEWEB)

    Arkhipov, N.I. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Bakhtin, V.P. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Safronov, V.M. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Toporkov, D.A. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Vasenin, S.G. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Wurz, H. [Kernforschungszentrum Karlsruhe, INR (Germany); Zhitlukhin, A.M. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation)

    1995-12-31

    Sudden evaporation of divertor plate surface under high heat load during tokamak plasma disruption instantaneously produces a vapor shield. The cloud of vaporized material prevents the divertor plates from the bulk of incoming energy flux and thus reduces the further material erosion. Dynamics and effectiveness of the vapor shield are studied experimentally at the 2MK-200 facility under simulated disruption conditions. (orig.).

  9. Target Housing Material Options

    Energy Technology Data Exchange (ETDEWEB)

    Woloshun, Keith Albert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-02-11

    With gas cooling, heat transfer coefficients are low compared to water. The benefit of gas from a heat transfer point of view is that there is really no upper temperature limit for the coolant, as compared to water, which is limited ultimately by the critical point, and in practice the critical heat flux. In our case with parallel flow channels, water is limited to even lower operating limits by nucleate boiling. So gas can get as hot as the containment material will allow, but to get the density and heat transfer up to something reasonable, we must also increase pressure, thus increasing stress on the containment, namely the front and back faces. We are designing to ASME BPVC, which, for most materials allows a maximum stress of UTS/3. So we want the highest possible UTS. For reference, the front face stress in the 12 mm target at 300 psi was about 90 MPa. The inconel 718 allowable stress at 900°C is 1/3 of 517 or 172 MPa. So we are in a very safe place, but the uTS is dropping rapidly with temperature above 900°C. As we increase target diameter, the challenge will be to keep the stress down. We are probably looking at keeping the allowable at or above the present value, and at as high a temperature as possible.

  10. US-Japan workshop Q-181 on high heat flux components and plasma-surface interactions for next devices: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, R.T. [ed.] [Sandia National Labs., Albuquerque, NM (United States); Yamashina, T. [ed.] [Hokkadio Univ. (Japan)

    1994-04-01

    This report contain viewgraphs of papers from the following sessions: plasma facing components issues for future machines; recent PMI results from several tokamaks; high heat flux technology; plasma facing components design and applications; plasma facing component materials and irradiation damage; boundary layer plasma; plasma disruptions; conditioning and tritium; and erosion/redeposition.

  11. Dissolved organic carbon in water fluxes of Eucalyptus grandis plantations in northeastern Entre Ríos Province, Argentina

    Science.gov (United States)

    Natalia Tesón; Víctor H Conzonno; Marcelo F Arturi; Jorge L Frangi

    2014-01-01

    Water fluxes in tree plantations and other ecosystems carry dissolved organic carbon (DOC) provided by atmospheric inputs, autotrophic and heterotrophic metabolisms and from the lysis of dead material. These compounds may be colorless or provide a yellow-to-brown color to water and may also absorb visible light due to the presence of chromophores in the chemical...

  12. Fluxing as a new tool for bitumen rheological characterization and the use of time-concentration shift factor (ac)

    CSIR Research Space (South Africa)

    Zoorob, SE

    2018-01-01

    Full Text Available and Building Materials, vol. 158: 691-699 Fluxing as a new tool for bitumen rheological characterization and the use of time-concentration shift factor (ac) Zoorob SE Mturi GA Sangiorgi C Dinis-Almeida M Habib NZ ABSTRACT: The concept...

  13. A Study of the Distribution of Flux Control Coefficients in an In Vitro Metabolic System: A Practical Exercise.

    Science.gov (United States)

    Torres, N. V.; And Others

    1988-01-01

    Presents a practical exercise that enables students to measure flux control coefficients in a metabolic pathway in vitro, to verify the summation property, and to compare the differences in the distribution of these coefficients in different steady states. Discusses background, materials, methods, and results of the activity. (CW)

  14. Depth profiling of the modification induced by high-flux deuterium plasma in tungsten and tungsten–tantalum alloys

    NARCIS (Netherlands)

    Zayachuk, Y.; Manhard, A.; Hoen, M. H. J. 't; Jacob, W.; van Emmichoven, P. A. Zeijlma; Van Oost, G.

    2014-01-01

    The present work reports the results of an experimental study of the depth distribution and fluence dependence of deuterium plasma-induced material modification of tungsten and tungsten–tantalum alloys. Plasma-induced damage was created by exposure to high-flux deuterium plasma in the plasma

  15. 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.

  16. Suprathermal Charged Particle Acceleration by Small-scale Flux Ropes.

    Science.gov (United States)

    Zank, G. P.; le Roux, J. A.; Webb, G. M.

    2015-12-01

    We consider different limits of our recently developed kinetic transport theory to investigate the potential of super-Alvenic solar wind regions containing several small-scale flux ropes to explain the acceleration of suprathermal ions to power-law spectra as observations show. Particle acceleration is modeled in response to flux-rope activity involving contraction, merging (reconnection), and collisions in the limit where the particle gyoradius is smaller than the characteristic flux-rope scale length. The emphasis is mainly on the statistical variance in the electric fields induced by flux-rope dynamics rather than on the mean electric field induced by multiple flux ropes whose acceleration effects are discussed elsewhere. Our steady-state analytical solutions suggest that particle drift acceleration by flux ropes, irrespective of whether displaying incompressible or compressible behavior, can yield power laws asymptotically at higher energies whereas an exponential spectral rollover results asymptotically when field-aligned guiding center motion acceleration occur by reconnection electric fields from merging flux ropes. This implies that at sufficiently high particle energies, drift acceleration might dominate. We also expect compressive flux ropes to yield harder power-law spectra than incompressible flux ropes. Preliminary results will be discussed to illustrate how particle acceleration might be affected when both diffusive shock and small-scale flux acceleration occur simultaneously at interplanetary shocks.

  17. Fluxes of Ultrafine Particles Over and In a Deciduous Forest

    Science.gov (United States)

    Pryor, S. C.; Hornsby, K. E.

    2013-12-01

    Given the importance of forests to land surface cover and particle removal (due to the very high deposition velocities and well-developed turbulence) there is a specific need to understand removal to, and in, forests. Fluxes of size-resolved and total particle number fluxes over (at 46 m) and in (at 7 m) a deciduous forest over a 14 month period are presented based on data from two Gill 3-D WindMaster Pro sonic anemometers, an Ultrafine Condensation Particle Counter (UCPC) operated at 10 Hz and a Fast Mobility Particle Sizer (FMPS) operated at 1 Hz. Size-resolved particle profiles during the same period are measured using a separate FMPS scanning at three measurement heights across the canopy (top, middle and bottom). Three methods are being applied to derive the total number and size-resolved fluxes from the UCPC and FMPS respectively; eddy covariance, inertial dissipation and the co-spectral approach. The results are integrated with fluxes of sensible heat, momentum and carbon dioxide derived using a Licor LI-7200. Results for the total number flux concentrations and the size-resolved concentrations derived using the three different approaches applied to the above canopy sampling level show a high degree of accord, but that the eddy-covariance fluxes are generally of smaller magnitude than those derived using the spectral methods. In keeping with prior research our results show a considerable number of fluxes are characterized by upward fluxes. Further our results show distinctly different flux diurnal profiles for the nucleation versus Aitken mode particles indicating some differential control on fluxes of particles of different sizes (including a role for aerosol dynamics). This presentation will provide details regarding the experimental approach, flux and gradient estimation methodologies, diagnose the size dependence of the fluxes, and compare and contrast the canopy and ground partitioning of the particle fluxes during leaf-on and leaf-off periods.

  18. Sand Flux Results for Aeolian Dunes at Current and Candidate Landing Sites on Mars

    Science.gov (United States)

    Chojnacki, M.; Urso, A.; Yingling, W.

    2015-12-01

    It is now known unambiguously that wind-driven bedform activity is occurring on Mars today. It has also been demonstrated the rapid aeolian abrasion of sedimentary deposits that potentially host ancient habitable environments may provide the best mechanism for exposing samples containing relatively undegraded organics (Farley et al. 2014). Thus, current processes operating on the surface of Mars are highly relevant to our understanding of the past. Here, we discuss new sand flux results of active dune across Mars, including several current and candidate landing sites with Meridiani Planum, Gale crater, Valles Marineris, and Mawrth Vallis. For this task, we have utilized multi-temporal images acquired annually by the HiRISE camera (25 cm/pixel) along with co-located HiRISE Digital Terrain Models. Falling dunes in Coprates Chasma (Mars 2020 candidate landing site) measuring 6-10 meters in height were detected migrating on average 0.5 m per Earth year, yielding crest fluxes of 3.1 m3 m-1 yr-1 (units hereafter assumed). Barchans near the MSL rover at Gale crater have slightly lower fluxes of 1.2, while earlier work in Endeavour crater, the current site of the Opportunity Rover, showed dome dunes with fluxes as high as 13 (average of 6.8; Chojnacki et al. 2015). New results of Mawrth Vallis (Mars 2020 candidate) dunes suggest these high rates are not uncommon, as barchans there possess average fluxes of 11.5. Assuming ripple reptation rates are 1/10th that of crest fluxes, total flux (saltation plus reptation) would range 3.2 to 12.7 m3 m-1 yr-1 for all sites studied herein. Active dunes and the abrasion susceptibility (Sa) of local rocks are relevant to assess how sand fluxes modify the landscape. Using the methodology and assumptions (Sa for basalt, mean trajectory height etc.) described in Bridges et al. (2012), we estimated abrasion rates of local basaltic bedrock. For example, sand blasting at Mawrth Vallis is estimated to produce 2-8 μm/yr for flat ground and 15

  19. Spatial and stress-related variation in benthic microbial gas flux in northeastern Alberta wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Ciborowski, J.; Gardner Costa, J. [Windsor Univ., ON (Canada)

    2010-07-01

    This study investigated the effects of oil sands process material (OSPM) on the sediment microbial respiration in newly constructed wetlands located in northeastern Alberta. The sediment gas flux in 10 wetlands with various sediment characteristics and ages was studied. Analyses of variance (ANOVA) were used to contrast the mean wetland production of methane (CH{sub 4}) and carbon dioxide (CO{sub 2}) with season, wetland status, wetland age, and wetland zones. The study showed that CH{sub 4} was significantly higher in reference wetlands than in OSPM-impacted wetlands. A significant relationship between the status and zone of the wetland was observed for CH{sub 4} fluxes in reference wetlands. CH{sub 4} fluxes were higher in the non-vegetated zones of reference wetlands than in the vegetated zones of reference wetlands. CO{sub 2} fluxes were low and not significantly different in any of the studied sites. Results indicated that the wetlands contributed little atmospheric carbon.

  20. High Heat Flux Testing of Tungsten PFCs for the Fusion Reactor Development

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Suk-Kwon; Park, Seong Dae; Jin, Hyung Gon; Lee, Eo Hwak; Yoon, Jae-Sung; Lee, Dong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Tungsten divertor plasma facing components (PFCs) were fabricated by using hot isostatic-pressing (HIP) bonding and vacuum plasma spray method (VPS) for the fusion reactor development. Tungsten mockups were designed for the high heat flux test with the Korean high heat flux test facility - electron beam (KoHLT-EB), which was constructed for the performance qualification of various PFCs. KoHLT-EB was used to qualify the PFCs performances of each fusion research. The high heat load conditions were simulated by using a thermo-hydraulic analysis tool with the ANSYS-CFX code. A high heat flux testing was performed up to the thermal life-time of each mockup with the evaluated conditions in 1 ⁓ 5 MW/m{sup 2}. HIP-bonded testing mockups consisted of 2 mm pure tungsten PFCs and ferritic-martensitic steel (FMS) as structural materials, and VPS mockups are comprised with 1 ⁓ 2 mm coated tungsten layer and FMS. These tungsten mockups are the candidate for the blanket and divertor in DEMO or a fusion power reactor. For the thermal fatigue test, two types of tungsten mock-ups were fabricated by using HIP bonding and VPS method for the fusion reactor development. The verification of the cooling performance was tested under the operation condition of ITER and fusion reactor. After the completion of the preliminary mockup test and facility qualification, the high heat flux test facility assess the performance test for two type of plasma facing components.

  1. A model for the prediction of safe heat flux from a downward-facing hot patch

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, C. Nowneswara; Jayanti, S., E-mail: sjayanti@iitm.ac.in

    2013-12-15

    Highlights: • Elucidation of the effect inclination on bubble size and shape. • Computational model for heat transfer under film boiling conditions. • Elucidation of heat leakage from a hot patch. • Development of a dimensionless correlation for safe heat flux. - Abstract: Pool boiling from the underside of flat, downward-facing patch is important in analyzing possible accident scenarios related to nuclear power generation. Significant deterioration in heat transfer may occur in stationary film boiling leading to high wall temperatures. In the present work, we have studied, experimentally and through computational fluid dynamics simulations, the nature of the bubbles that are formed at a hot patch. Noting that large, flattened bubbles can be formed at a heated surface, we develop a heat transfer-only model which takes into account the conduction within the plate and the convective and boiling heat transfer to the surrounding liquid medium. It is shown that the safe heat flux, beyond which significant wall temperature rise may occur, is very small compared the critical heat flux for thick plates made of poorly conducting materials. A dimensionless correlation is proposed to calculate the safe heat flux.

  2. Harvesting microalgal biomass using crossflow membrane filtration: critical flux, filtration performance, and fouling characterization.

    Science.gov (United States)

    Elcik, Harun; Cakmakci, Mehmet

    2017-06-01

    The purpose of this study was to investigate the efficient harvesting of microalgal biomass through crossflow membrane filtration. The microalgal biomass harvesting experiments were performed using one microfiltration membrane (pore size: 0.2 µm, made from polyvinylidene fluoride) and three ultrafiltration membranes (molecular weight cut-off: 150, 50, and 30 kDa, made from polyethersulfone, hydrophilic polyethersulfone, and regenerated cellulose, respectively). Initially, to minimize membrane fouling caused by microalgal cells, experiments with the objective of determining the critical flux were performed. Based on the critical flux calculations, the best performing membrane was confirmed to be the UH050 membrane, produced from hydrophilic polyethersulfone material. Furthermore, we also evaluated the effect of transmembrane pressure (TMP) and crossflow velocity (CFV) on filtration flux. It was observed that membrane fouling was affected not only by the membrane characteristics, but also by the TMP and CFV. In all the membranes, it was observed that increasing CFV was associated with increasing filtration flux, independent of the TMP.

  3. Study of materials used for the thermal protection of the intake system for internal combustion engines

    Science.gov (United States)

    Birtok-Băneasă, C.; Raţiu, S.; Puţan, V.; Josan, A.

    2018-01-01

    The present paper focuses on calculation of thermal conductivity for a new materials developed by the authors, using the heat flux plate method. This experimental method consists in placing the sample of the new material in a calorimetric chamber and heating from underside. As the heat flux which passes through the sample material is constant and knowing the values of the temperatures for the both sides of sample, the sample material thermal conductivity is determined. Six types of different materials were tested. Based on the experimental data, the values of the thermal conductivity according to the material and the average temperature were calculated and plotted.

  4. Magnetic properties of high-T(sub c) superconductors: Rigid levitation, flux pinning, thermal depinning, and fluctuation

    Science.gov (United States)

    Brandt, E. H.

    1990-01-01

    The levitation of high-T(sub c) superconductors is quite conspicuous: Above magnets of low symmetry a disk of these ceramics floats motionless, without vibration or rotation; it has a continuous range of stable positions and orientations as if it were stuck in sand. Some specimens may even be suspended above or below the same magnet. This fascinating stability, inherent to no other type of levitation, is caused by the pinning of magnetic flux lines by inhomogeneities inside these extreme type-2 superconductors. The talk deals with pinning of magnetic flux in these materials, with flux flow, flux creep, thermally activated depinning, and the thermal fluctuation of the vortex positions in the flux line lattice (often called flux lattice melting). Also discussed are the fluctuations of the (nearly periodic) magnetic field inside these superconductors which are caused by random pinning sites and by the finite temperature. These fluctuations broaden the van-Hove singularities observed in the density of the magnetic field by nuclear magnetic resonance and by muon spin rotation.

  5. Materials And Processes Technical Information System (MAPTIS) LDEF materials data base

    Science.gov (United States)

    Funk, Joan G.; Strickland, John W.; Davis, John M.

    1993-01-01

    A preliminary Long Duration Exposure Facility (LDEF) Materials Data Base was developed by the LDEF Materials Special Investigation Group (MSIG). The LDEF Materials Data Base is envisioned to eventually contain the wide variety and vast quantity of materials data generated from LDEF. The data is searchable by optical, thermal, and mechanical properties, exposure parameters (such as atomic oxygen flux) and author(s) or principal investigator(s). Tne LDEF Materials Data Base was incorporated into the Materials and Processes Technical Information System (MAPTIS). MAPTIS is a collection of materials data which has been computerized and is available to engineers, designers, and researchers in the aerospace community involved in the design and development of spacecraft and related hardware. The LDEF Materials Data Base is described and step-by-step example searches using the data base are included. Information on how to become an authorized user of the system is included.

  6. Virtual materiality

    DEFF Research Database (Denmark)

    Søndergaard, Dorte Marie

    . Butler, J. (1993) Bodies that Matter. On the Discursive Limits of “Sex”. London: Routledge. Durkin, K. et al. (1998) Children, Media and Agression. Current Research in Australia and New Zealand. In: Carlson, U. & von Feilitzen, C. (red): Children and Media Violence. Yearbook from the UNESCO International...... be discarded as analytical input to discussions about materiality? How far can we develop and stretch our conceptual understanding of the material? (Søndergaard 2009b) Theorizing creates new patterns of visibility and invisibility - with all the potentialities in between. Bullying research is a field that begs...... for new theorizing and new analytical tools. (Søndergaard 2008, 2009a) It is a field that deals with children’s individual and collective processes of becoming, of materializing and of entering in and as agentic part(ner)s of the human and non-human world. But current theoretical premises in that field...

  7. Atmospheric materiality

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2016-01-01

    A disjunction between the material and the immaterial has been at the heart of the architectural debate for decades. In this dialectic tension, the notion of atmosphere which increasingly claims attention in architectural discourse seems to be parallactic, leading to the re-evaluation of perceptual...... experience and, consequently, to the conceptual and methodological shifts in the production of space, and hence in the way we think about materiality. In this context, architectural space is understood as a contingent construction – a space of engagement that appears to us as a result of continuous...... and complex interferences revealed through our perception; ‘the atmospheric’ is explored as a spatial and affective quality as well as a sensory background, and materiality as a powerful and almost magical agency in shaping of atmosphere. Challenging existing dichotomies and unraveling intrinsic...

  8. Layered materials

    Science.gov (United States)

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and

  9. Magnetic Materials

    Science.gov (United States)

    1985-03-01

    L -:• •.1 S..+.: s• S,’S .+m • , ++ d ’N .,.++.+ ii L+ i+- -..’ *4’.. ’-t. COMM4ITTEE ON MAGNETIC MATERIALS Chairman ROBERT M. WRITE, Principal...Motors; Sung Ho Jin, AT&T Bell Labs; G. Rodrigue, ... -- =.• Georgia Tech; J. Houze , Allegheny-Ludlum; R. Sundahl, AT&T Bell Labs; (. I... R. O’Handley...this report. Robert M. White Chairman *’-’ . ,i-.. .- ABSTRACT Magnetic materials play a fundamental role in many of the electrical and electronic

  10. Electronic materials

    CERN Document Server

    Kwok, H L

    2010-01-01

    The electronic properties of solids have become of increasing importance in the age of information technology. The study of solids and materials, while having originated from the disciplines of physics and chemistry, has evolved independently over the past few decades. The classical treatment of solid-state physics, which emphasized classifications, theories and fundamental physical principles, is no longer able to bridge the gap between materials advances and applications. In particular, the more recent developments in device physics and technology have not necessarily been driven by new conc

  11. 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...

  12. Disjunct eddy covariance technique for trace gas flux measurements

    Science.gov (United States)

    Rinne, H. J. I.; Guenther, A. B.; Warneke, C.; de Gouw, J. A.; Luxembourg, S. L.

    A new approach for eddy covariance flux measurements is developed and applied for trace gas fluxes in the atmospheric surface layer. In disjunct eddy covariance technique, quick samples with a relatively long time interval between them are taken instead of continuously sampling air. This subset of the time series together with vertical wind velocity data at corresponding sampling times can be correlated to give a flux. The disjunct eddy sampling gives more time to analyze the trace gas concentrations and thus makes eddy covariance measurements possible using slower sensors. In this study a proton-transfer-reaction mass spectrometer with response time of about 1 second was used with a disjunct eddy sampler to measure fluxes of volatile organic compounds from an alfalfa field. The measured day-time maximum methanol fluxes ranged from 1 mg m-2 h-1 from uncut alfalfa to 8 mg m-2 h-1 from freshly cut alfalfa. Night-time fluxes were around zero.

  13. Heat flux measurement in SSME turbine blade tester

    Science.gov (United States)

    Liebert, Curt H.

    1990-01-01

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

  14. "Active Flux" DTFC-SVM Sensorless Control of IPMSM

    DEFF Research Database (Denmark)

    Boldea, Ion; Codruta Paicu, Mihaela; Gheorghe-Daniel, Andreescu,

    2009-01-01

    This paper proposes an implementation of a motionsensorless control system in wide speed range based on "active flux" observer, and direct torque and flux control with space vector modulation (DTFC-SVM) for the interior permanent magnet synchronous motor (IPMSM), without signal injection...... is obtained, because the active flux position is identical with the rotor position. Extensive experimental results are presented to verify the principles and to demonstrate the effectiveness of the proposed sensorless control system. With the active flux observer, the IPMSM drive system operates from very low....... The concept of "active flux" (or "torque producing flux") turns all the rotor salient-pole ac machines into fully nonsalient-pole ones. A new function for Lq inductance depending on torque is introduced to model the magnetic saturation. Notable simplification in the rotor position and speed estimation...

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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...... production of investigated substrate combinations was significantly reduced in mitochondria isolated from type 2 diabetic subjects compared to lean. However, when ATP synthesis rates at different substrate combinations were normalized to the corresponding individual pyruvate-malate rate...

  1. Plastic scintillator detector for pulsed flux measurements

    Science.gov (United States)

    Kadilin, V. V.; Kaplun, A. A.; Taraskin, A. A.

    2017-01-01

    A neutron detector, providing charged particle detection capability, has been designed. The main purpose of the detector is to measure pulsed fluxes of both charged particles and neutrons during scientific experiments. The detector consists of commonly used neutron-sensitive ZnS(Ag) / 6LiF scintillator screens wrapping a layer of polystyrene based scintillator (BC-454, EJ-254 or equivalent boron loaded plastic). This type of detector design is able to log a spatial distribution of events and may be scaled to any size. Different variations of the design were considered and modelled in specialized toolkits. The article presents a review of the detector design features as well as simulation results.

  2. Probabilistic Forecasting of the Wave Energy Flux

    DEFF Research Database (Denmark)

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

    2012-01-01

    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......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......% and 70% in terms of Continuous Rank Probability Score (CRPS), depending upon the test case and the lead time. It is finally shown that the log-Normal assumption can be seen as acceptable, even though it may be refined in the future....

  3. 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

  4. Compressed magnetic flux amplifier with capacitive load

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Time dependences of atmospheric Carbon dioxide fluxes

    CERN Document Server

    DeSalvo, Riccardo

    2014-01-01

    Understanding the lifetime of CO2 in the atmosphere is critical for predictions regarding future climate changes. A simple mass conservation analysis presented here generates tight estimations for the atmosphere's retention time constant. The analysis uses a leaky integrator model that combines the observed deficit (only less than 40% of CO2 produced from combustion of fossil fuels is actually retained in the atmosphere, while more than 60% is continuously shed) with the exponential growth of fossil fuel burning. It reveals a maximum characteristic time of less than 23 year for the transfer of atmospheric CO2 to a segregation sink. This time constant is further constrained by the rapid disappearance of 14C after the ban of atmospheric atomic bomb tests, which provides a lower limit of 18 years for this transfer. The study also generates evaluations of other CO2 fluxes, exchange time constants and volumes exchanged. Analysis of large harmonic oscillations of atmospheric CO2 concentration, often neglected in th...

  6. Coulomb flux tube on the lattice

    Science.gov (United States)

    Chung, Kristian; Greensite, Jeff

    2017-08-01

    In Coulomb gauge a longitudinal electric field is generated instantaneously with the creation of a static quark-antiquark pair. The field due to the quarks is a sum of two contributions, one from the quark and one from the antiquark, and there is no obvious reason that this sum should fall off exponentially with distance from the sources. We show here, however, from numerical simulations in pure SU(2) lattice gauge theory, that the color Coulomb electric field does in fact fall off exponentially with transverse distance away from a line joining static quark-antiquark sources, indicating the existence of a color Coulomb flux tube, and the absence of long-range Coulomb dipole fields.

  7. Renewed experimentation with Ranchero flux compression genereators

    Energy Technology Data Exchange (ETDEWEB)

    Goforth, James H [Los Alamos National Laboratory; Herrera, Dennis H [Los Alamos National Laboratory; Tasker, Douglas G [Los Alamos National Laboratory; Torres, David T [Los Alamos National Laboratory; Atchison, W. L. [Los Alamos National Laboratory; Colgate, S. A. [Los Alamos National Laboratory; Griego, J. R. [Los Alamos National Laboratory; Guzik, J. [Los Alamos National Laboratory; Holtkamp, D. B. [Los Alamos National Laboratory; Idzorek, G. [Los Alamos National Laboratory; Kaul, A [Los Alamos National Laboratory; Kirkpatrick, R. C. [Los Alamos National Laboratory; Menikoff, R. [Los Alamos National Laboratory; Meyer, R. K. [Los Alamos National Laboratory; Oona, H. [Los Alamos National Laboratory; Reardon, P. T. [Los Alamos National Laboratory; Reinovsky, R. E. [Los Alamos National Laboratory; Rousculp, C. L. [Los Alamos National Laboratory; Sgro, A. G. [Los Alamos National Laboratory; Tabaka, L. J. [Los Alamos National Laboratory; Watt, R. G. [Los Alamos National Laboratory; Riesman, D. B. [LLNL

    2010-11-08

    In the late 1990s, Los Alamos pursued a coaxial flux compression generator (FCG) concept that was described in several publications under the name 'Ranchero.' These FCGs were designed to be cost effective high current generators, and a variety of configurations were tested. The Ranchero armature is a 152 mm diameter aluminum cylinder with a 6 mm thick wall. The high explosive (HE) is detonated simultaneously on axis, and as the armature expands a factor of two, the wall thins to {approx}3 mm. At the final 300 mm diameter, the circumference is over 900 mm, and this should allow currents to be generated in the 90 MA range. No tests significantly over 50 MA have been performed but an experiment is planned. We have recently begun using Ranchero devices for a new application and we continue to improve the design. In this paper we describe recent tests of Ranchero and its subsystems. The load for our new application is an imploding aluminum liner that would deform due to the magnetic pressure applied during the initial flux loading. It will, however, implode properly when powered only during the {approx}29 {micro}s Ranchero flux compression time. This gives rise to a new system with explOSively formed fuse (EFF) opening switches and an integral closing switch that isolates the load. A capacitor bank delivers 2.8 MA to the Ranchero circuit in {approx}85 {micro}s. During this time, four parallel 63.5 mm wide EFFs, external to the coaxial system, complete the circuit. After armature motion begins, insulation which initially isolates the load is severed, connecting the load to the FCG in parallel with the EFFs. External HE charges are initiated on each of the EFFs to produce a resistance rise timed to not precede closure of the load isolation switch. The EFFs achieve significant resistance, and the flux remaining in the 191 nH generator and 3 nH transmission line is compressed to generate 30.85 MA in a {approx}12.5 nH static load. On three tests, the EFF system has

  8. 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.

  9. 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.)

  10. HONO fluxes from soil surfaces: an overview

    Science.gov (United States)

    Wu, Dianming; Sörgel, Matthias; Tamm, Alexandra; Ruckteschler, Nina; Rodriguez-Caballero, Emilio; Cheng, Yafang; Pöschl, Ulrich; Weber, Bettina

    2016-04-01

    Gaseous nitrous acid (HONO) contributes up to 80% of atmospheric hydroxyl (OH) radicals and is also linked to health risks through reactions with tobacco smoke forming carcinogens. Field and modeling results suggested a large unknown HONO source in the troposphere during daytime. By measuring near ground HONO mixing ratio, up to 30% of HONO can be released from forest, rural and urban ground as well as snow surfaces. This source has been proposed to heterogeneous reactions of nitrogen dioxide (NO2) on humic acid surfaces or nitric acid photolysis. Laboratory studies showed that HONO emissions from bulk soil samples can reach 258 ng m-2 s-1 (in term of nitrogen), which corresponding to 1.1 × 1012 molecules cm-2 s-1and ˜ 100 times higher than most of the field studies, as measured by a dynamic chamber system. The potential mechanisms for soil HONO emissions include chemical equilibrium of acid-base reaction and gas-liquid partitioning between soil nitrite and HONO, but the positive correlation of HONO fluxes with pH (largest at neutral and slightly alkaline) points to the dominance of the formation process by ammonia-oxidizing bacteria (AOB). In general soil surface acidity, nitrite concentration and abundance of ammonia-oxidizing bacteria mainly regulate the HONO release from soil. A recent study showed that biological soil crusts in drylands can also emit large quantities of HONO and NO, corresponding to ˜20% of global nitrogen oxide emissions from soils under natural vegetation. Due to large concentrations of microorganisms in biological soil crusts, particularly high HONO and NO emissions were measured after wetting events. Considering large areas of arid and arable lands as well as peatlands, up to 70% of global soils are able to emitting HONO. However, the discrepancy between large soil HONO emissions measured in lab and low contributions of HONO flux from ground surfaces in field as well as the role of microorganisms should be further investigated.

  11. 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.

  12. 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.

  13. VERTIGO (VERtical Transport In the Global Ocean): A study of particle sources and flux attenuation in the North Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Buesseler, K.O.; Trull, T.W.; Steinberg, D.K.; Silver, M.W.; Siegel, D.A.; Saitoh, S.-I.; Lamborg, C.H.; Lam, P.J.; Karl, D.M.; Jiao, N.Z.; Honda, M.C.; Elskens, M.; Dehairs, F.; Brown, S.L.; Boyd, P.W.; Bishop, J.K.B.; Bidigare, R.R.

    2008-06-10

    The VERtical Transport In the Global Ocean (VERTIGO) study examined particle sources and fluxes through the ocean's 'twilight zone' (defined here as depths below the euphotic zone to 1000 m). Interdisciplinary process studies were conducted at contrasting sites off Hawaii (ALOHA) and in the NW Pacific (K2) during 3 week occupations in 2004 and 2005, respectively. We examine in this overview paper the contrasting physical, chemical and biological settings and how these conditions impact the source characteristics of the sinking material and the transport efficiency through the twilight zone. A major finding in VERTIGO is the considerably lower transfer efficiency (T{sub eff}) of particulate organic carbon (POC), POC flux 500/150 m, at ALOHA (20%) vs. K2 (50%). This efficiency is higher in the diatom-dominated setting at K2 where silica-rich particles dominate the flux at the end of a diatom bloom, and where zooplankton and their pellets are larger. At K2, the drawdown of macronutrients is used to assess export and suggests that shallow remineralization above our 150 m trap is significant, especially for N relative to Si. We explore here also surface export ratios (POC flux/primary production) and possible reasons why this ratio is higher at K2, especially during the first trap deployment. When we compare the 500 m fluxes to deep moored traps, both sites lose about half of the sinking POC by >4000 m, but this comparison is limited in that fluxes at depth may have both a local and distant component. Certainly, the greatest difference in particle flux attenuation is in the mesopelagic, and we highlight other VERTIGO papers that provide a more detailed examination of the particle sources, flux and processes that attenuate the flux of sinking particles. Ultimately, we contend that at least three types of processes need to be considered: heterotrophic degradation of sinking particles, zooplankton migration and surface feeding, and lateral sources of

  14. Materials irradiation research in neutron science

    Energy Technology Data Exchange (ETDEWEB)

    Noda, Kenji; Oyama, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-11-01

    Materials irradiation researches are planned in Neutron Science Research Program. A materials irradiation facility has been conceived as one of facilities in the concept of Neutron Science Research Center at JAERI. The neutron irradiation field of the facility is characterized by high flux of spallation neutrons with very wide energy range up to several hundred MeV, good accessibility to the irradiation field, good controllability of irradiation conditions, etc. Extensive use of such a materials irradiation facility is expected for fundamental materials irradiation researches and R and D of nuclear energy systems such as accelerator-driven incineration plant for long-lifetime nuclear waste. In this paper, outline concept of the materials irradiation facility, characteristics of the irradiation field, preliminary technical evaluation of target to generate spallation neutrons, and materials researches expected for Neutron Science Research program are described. (author)

  15. Quantifying the "chamber effect" in CO2 flux measurements

    Science.gov (United States)

    Vihermaa, Leena; Childs, Amy; Long, Hazel; Waldron, Susan

    2014-05-01

    The significance of aquatic CO2 emissions has received attention in recent years. For example annual aquatic emissions in the Amazon basin have been estimated as 500 Mt of carbon1. Methods for determining the flux rates include eddy covariance flux tower measurements, flux estimates calculated from partial pressure of CO2 (pCO2) in water and the use floating flux chambers connected to an infra-red gas analyser. The flux chamber method is often used because it is portable, cheaper and allows smaller scale measurements. It is also a direct method and hence avoids problems related to the estimation of the gas transfer coefficient that is required when fluxes are calculated from pCO2. However, the use of a floating chamber may influence the flux measurements obtained. The chamber shields the water underneath from effects of wind which could lead to lower flux estimates. Wind increases the flux rate by i) causing waves which increase the surface area for efflux, and ii) removing CO2 build up above the water surface, hence maintaining a higher concentration gradient. Many floating chambers have an underwater extension of the chamber below the float to ensure better seal to water surface and to prevent any ingress of atmospheric air when waves rock the chamber. This extension may cause additional turbulence in flowing water and hence lead to overestimation of flux rates. Some groups have also used a small fan in the chamber headspace to ensure thorough mixing of air in the chamber. This may create turbulence inside the chamber which could increase the flux rate. Here we present results on the effects of different chamber designs on the detected flux rates. 1Richey et al. 2002. Outgassing from Amazonian rivers and wetlands as a large tropical source of atmospheric CO2. Nature 416: 617-620.

  16. The Topology of Canonical Flux Tubes in Flared Jet Geometry

    OpenAIRE

    Lavine, Eric Sander; You, Setthivoine

    2017-01-01

    Magnetized plasma jets are generally modeled as magnetic flux tubes filled with flowing plasma governed by magnetohydrodynamics (MHD). We outline here a more fundamental approach based on flux tubes of canonical vorticity, where canonical vorticity is defined as the circulation of the species canonical momentum. This approach extends the concept of magnetic flux tube evolution to include the effects of finite particle momentum and enables visualization of the topology of plasma jets in regime...

  17. 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

  18. Emerging Materiality

    DEFF Research Database (Denmark)

    Bertelsen, Olav Wedege; Breinbjerg, Morten; Pold, Søren

    2009-01-01

    The authors examine how materiality emerges from complex chains of mediation in creative software use. The primarily theoretical argument is inspired and illustrated by interviews with two composers of electronic music. The authors argue that computer mediated activity should not primarily...

  19. Creating Materials.

    Science.gov (United States)

    Yin, Mary

    1990-01-01

    Describes practical materials that relate to places within the English-as-a-Second-Language learner's own community, such as the supermarket, local fast food restaurants, pharmacy, and library. Each literacy booklet contains approximately 35 pages of activities that can be used as classroom handouts. (LB)

  20. Supplementary Material

    Indian Academy of Sciences (India)

    mraga

    1. Supplementary Material. A soluble-lead Redox Flow Battery with corrugated graphite sheet and reticulated vitreous carbon as positive and negative current collectors by A Banerjee et al (pp 163-. 170). Figure S1. SEM images for bare substrates: (a) graphite sheet, (b) 20 ppi RVC, (c) 30 ppi. RVC and (d) 45 ppi RVC.

  1. Temporal variability of vertical export flux at the DYFAMED time-series station (Northwestern Mediterranean Sea)

    Science.gov (United States)

    Heimbürger, Lars-Eric; Lavigne, Héloïse; Migon, Christophe; D'Ortenzio, Fabrizio; Estournel, Claude; Coppola, Laurent; Miquel, Juan-Carlos

    2013-12-01

    The temporal evolution of the vertical export flux at the DYFAMED time-series station (Ligurian Sea) over the last 20 years reveals a strong interannual variability. Winter convection allows particulate (and dissolved) matter to be vertically exported (“flush-down” effect). The efficiency of this process determines also the concentration of nutrients brought to surface waters and, therefore, the intensity of the subsequent phytoplankton bloom. The sequence “convection-bloom” is the main driving force of vertical export flux in this region. The present work attempts to better identify the parameters that control vertical export flux dynamics by observing a 20 year time-series in relation with the temporal variability of mixed layer depth and surface primary production. The consequences of a more stratified water column in the future on biological productivity and vertical export flux are pointed out. In winter, the cooling of surface water, combined with evaporation, increases its density and determines the vertical convection. This allows for a rapid downward transfer of dissolved and particulate matter, yielding high vertical export flux. This “flush-down effect” results from a combination of convection and gravitational flux, since the diving of dense surface waters breaks the stratification of the water column and carries all material (particulate + dissolved) accumulated in the surface layer to depth. The rapid downward transfer of dissolved and particulate matter by this “flush-down effect” yields high vertical export fluxes. The magnitude of these fluxes may vary according to the amount of atmospheric material accumulated in surface waters during the preceding stratified period. In the present data set, highest vertical export fluxes were observed in 1999, 2003 and 2004. In those years, the MLD was greater (Fig. 2), suggesting a causal relationship between the efficiency of vertical mixing and the subsequent vertical export flux. In spring

  2. Validation of PICA Ablation and Thermal-Response Model at Low Heat Flux

    Science.gov (United States)

    Milos, Frank S.; Chen, Yih-Kanq

    2009-01-01

    Phenolic Impregnated Carbon Ablator (PICA) was the forebody heatshield material on the Stardust sample-return capsule and is also a primary candidate material for the Mars Science Lander (MSL), the Orion Crew Module, and the SpaceX Dragon vehicle. As part of the heatshield qualification for Orion, physical and thermal properties of virgin and charred PICA were measured, and an ablation and thermal response model was developed. We validated the model by comparing it with recession and temperature data from stagnation arcjet tests conducted over a wide range of stagnation heat flux of 107 to 1102 W/sq cm. The effect of orthotropic thermal conductivity was evident in the thermal response of the arcjet models. In general, model predictions compared well with the data; however, the uncertainty of the recession prediction was greatest for heat fluxes below 200 W/sq cm. More recent MSL testing focused on the low heat flux regime of 45 to 250 W/sq cm. The new results confirm the recession uncertainty, especially for pressures below 6 kPa. In this work we focus on improving the model predictions for MSL and Orion tests below 250 W/sq cm.

  3. Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux

    Science.gov (United States)

    Bowman, C.D.

    1992-11-03

    Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

  4. Extraterrestrial flux of potentially prebiotic C, N, and P to the early Earth.

    Science.gov (United States)

    Pasek, Matthew; Lauretta, Dante

    2008-02-01

    With growing evidence for a heavy bombardment period ending 4-3.8 billion years ago, meteorites and comets may have been an important source of prebiotic carbon, nitrogen, and phosphorus on the early Earth. Life may have originated shortly after the late-heavy bombardment, when concentrations of organic compounds and reactive phosphorus were enough to "kick life into gear". This work quantifies the sources of potentially prebiotic, extraterrestrial C, N, and P and correlates these fluxes with a comparison to total Ir fluxes, and estimates the effect of atmosphere on the survival of material. We find (1) that carbonaceous chondrites were not a good source of organic compounds, but interplanetary dust particles provided a constant, steady flux of organic compounds to the surface of the Earth, (2) extraterrestrial metallic material was much more abundant on the early Earth, and delivered reactive P in the form of phosphide minerals to the Earth's surface, and (3) large impacts provided substantial local enrichments of potentially prebiotic reagents. These results help elucidate the potential role of extraterrestrial matter in the origin of life.

  5. 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.

  6. 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...

  7. Nitrous oxide fluxes from tree stems in temperate forest ecosystems

    Science.gov (United States)

    Wen, Y.; Corre, M. D.; Veldkamp, E.

    2016-12-01

    Investigations on tree-mediated N2O fluxes are rare and restricted mostly to seedlings and saplings. Presently, little is known about N2O fluxes from mature trees in field conditions as well as their contributions to total forest N2O fluxes. Here we quantified in situ stem N2O fluxes from mature alder trees on poorly-drained soil and mature beech and spruce trees on well-drained soil in Solling, Germany from March to October 2015. Soil N2O fluxes, soil N2O concentrations in 40-cm depth and other environmental factors were also measured simultaneously. In the present study, alder, beech and spruce consistently emitted N2O via stems and all displayed higher emission rates in summer than in spring and autumn. Stem N2O fluxes increased with increasing air and soil temperature, suggesting the influence of temperature on soil N2O production and soil-plant N2O transport (via transpiration stream). Increased in vapor pressure deficit speeded up stem N2O fluxes in alder and spruce, possibly because of enhanced sap flow rates and the subsequent dissolved N2O transport rates. In the alder stand, the significant correlations between stem N2O fluxes, soil N2O fluxes and soil N2O concentrations suggest that N2O transport may have been facilitated by a combination of passive diffusion and convective mechanisms. In the beech and spruce stands, the significant correlations between stem N2O fluxes, temperature and vapor pressure deficit suggest convective transport of soil N2O to the stem. Overall, stem N2O fluxes from alder were higher than beech and spruce due to the presence of aerenchyma and lenticels as well as higher soil water content and soil N availability in the alder stand. Stem N2O fluxes represented 8-11% of the total N2O fluxes in the spruce and beech stands, whereas in the alder stand with large soil N2O fluxes its stem emissions contributed only 1% to total N2O fluxes. Our study provided information of hitherto unknown tree-mediated N2O contribution to forest N2O

  8. Applicability/evaluation of flux based representations for linear/higher order elements for heat transfer in structures - Generalized gamma(T)-family

    Science.gov (United States)

    Namburu, R. R.; Tamma, K. K.

    1991-01-01

    The applicability and evaluation of a generalized gamma(T) family of flux-based representations are examined for two different thermal analysis formulations for structures and materials which exhibit no phase change effects. The so-called H-theta and theta forms are demonstrated for numerous test models and linear and higher-order elements. The results show that the theta form with flux-based representations is generally superior to traditional approaches.

  9. Friction Material Composites Materials Perspective

    CERN Document Server

    Sundarkrishnaa, K L

    2012-01-01

    Friction Material Composites is the first of the five volumes which strongly educates and updates engineers and other professionals in braking industries, research and test labs. It explains besides the formulation of design processes and its complete manufacturing input. This book gives an idea of mechanisms of friction and how to control them by designing .The book is  useful for designers  of automotive, rail and aero industries for designing the brake systems effectively with the integration of friction material composite design which is critical. It clearly  emphasizes the driving  safety and how serious designers should  select the design input. The significance of friction material component like brake pad or a liner as an integral part of the brake system of vehicles is explained. AFM pictures at nanolevel illustrate broadly the explanations given.

  10. 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.

  11. High-Flux Carbon Molecular Sieve Membranes for Gas Separation.

    Science.gov (United States)

    Richter, Hannes; Voss, Hartwig; Kaltenborn, Nadine; Kämnitz, Susanne; Wollbrink, Alexander; Feldhoff, Armin; Caro, Jürgen; Roitsch, Stefan; Voigt, Ingolf

    2017-06-26

    Carbon membranes have great potential for highly selective and cost-efficient gas separation. Carbon is chemically stable and it is relative cheap. The controlled carbonization of a polymer coating on a porous ceramic support provides a 3D carbon material with molecular sieving permeation performance. The carbonization of the polymer blend gives turbostratic carbon domains of randomly stacked together sp2 hybridized carbon sheets as well as sp3 hybridized amorphous carbon. In the evaluation of the carbon molecular sieve membrane, hydrogen could be separated from propane with a selectivity of 10 000 with a hydrogen permeance of 5 m3 (STP)/(m2 hbar). Furthermore, by a post-synthesis oxidative treatment, the permeation fluxes are increased by widening the pores, and the molecular sieve carbon membrane is transformed from a molecular sieve carbon into a selective surface flow carbon membrane with adsorption controlled performance and becomes selective for carbon dioxide. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Fast Flux Test Facility Asbestos Location Tracking Program

    Energy Technology Data Exchange (ETDEWEB)

    REYNOLDS, J.A.

    1999-04-13

    Procedure Number HNF-PRO-408, revision 0, paragraph 1.0, ''Purpose,'' and paragraph 2.0, ''Requirements for Facility Management of Asbestos,'' relate building inspection and requirements for documentation of existing asbestos-containing building material (ACBM) per each building assessment. This documentation shall be available to all personnel (including contractor personnel) entering the facility at their request. Corrective action was required by 400 Area Integrated Annual Appraisal/Audit for Fiscal Year 1992 (IAA-92-0007) to provide this notification documentation. No formal method had been developed to communicate the location and nature of ACBM to maintenance personnel in the Fast Flux Test Facility (FFTF) 400 Area. The scope of this Data Package Document is to locate and evaluate any ACBM found at FFTF which constitutes a baseline. This includes all buildings within the protected area. These findings are compiled from earlier reports, numerous work packages and engineering evaluations of employee findings.

  13. Export stoichiometry and migrant-mediated flux of phosphorus in the North Pacific Subtropical Gyre

    Science.gov (United States)

    Hannides, Cecelia C. S.; Landry, Michael R.; Benitez-Nelson, Claudia R.; Styles, Renée M.; Montoya, Joseph P.; Karl, David M.

    2009-01-01

    Export processes play a major role in regulating global marine primary production by reducing the efficiency of nutrient cycling and turnover in surface waters. Most studies of euphotic zone export focus on passive fluxes, that is, sinking particles. However, active transport, the vertical transfer of material by migrating zooplankton, can also be an important component of carbon (C) and nitrogen (N) removal from the surface ocean. Here we demonstrate that active transport is an especially important mechanism for phosphorus (P) removal from the euphotic zone at Station ALOHA (Hawaii Ocean Time-series program; 22°45'N, 158°W), a P-stressed site in the North Pacific Subtropical Gyre. Migrant excretions in this region are P-rich (C 51:N 12:P 1) relative to sinking particles (C 250:N 31:P 1), and migrant-mediated P fluxes are almost equal in magnitude (82%) to P fluxes from sediment traps. Migrant zooplankton biomass and therefore the importance of this P removal pathway relative to sinking fluxes has increased significantly over the past 12 years, suggesting that active transport may be a major driving force for enhanced P-limitation of biological production in the NPSG. We further assess the C:N:P composition of zooplankton size fractions at Station ALOHA (C 88:N 18:P 1, on average) and discuss migrant-mediated P export in light of the balance between zooplankton and suspended particle stoichiometries. We conclude that, because active transport is such a large component of the total P flux and significantly impacts ecosystem stoichiometry, export processes involving migrant zooplankton must be included in large-scale efforts to understand biogeochemical cycles.

  14. Sediment carbon and nutrient fluxes from cleared and intact temperate mangrove ecosystems and adjacent sandflats.

    Science.gov (United States)

    Bulmer, Richard H; Schwendenmann, Luitgard; Lohrer, Andrew M; Lundquist, Carolyn J

    2017-12-01

    The loss of mangrove ecosystems is associated with numerous impacts on coastal and estuarine function, including sediment carbon and nutrient cycling. In this study we compared in situ fluxes of carbon dioxide (CO2) from the sediment to the atmosphere, and fluxes of dissolved inorganic nutrients and oxygen across the sediment-water interface, in intact and cleared mangrove and sandflat ecosystems in a temperate estuary. Measurements were made 20 and 25months after mangrove clearance, in summer and winter, respectively. Sediment CO2 efflux was over two-fold higher from cleared than intact mangrove ecosystems at 20 and 25months after mangrove clearance. The higher CO2 efflux from the cleared site was explained by an increase in respiration of dead root material along with sediment disturbance following mangrove clearance. In contrast, sediment CO2 efflux from the sandflat site was negligible (≤9.13±1.18mmolm(-2)d(-1)), associated with lower sediment organic matter content. The fluxes of inorganic nutrients (NH4(+), NOx and PO4(3-)) from intact and cleared mangrove sediments were low (≤20.37±18.66μmolm(-2)h(-)(1)). The highest NH4(+) fluxes were measured at the sandflat site (69.21±13.49μmolm(-2)h(-)(1)). Lower inorganic nutrient fluxes within the cleared and intact mangrove sites compared to the sandflat site were associated with lower abundance of larger burrowing macrofauna. Further, a higher fraction of organic matter, silt and clay content in mangrove sediments may have limited nutrient exchange. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Bedload transport flux fluctuations over a wide range of time scales

    Science.gov (United States)

    Ma, H.; Fu, X.; Ancey, C.

    2014-12-01

    Bedload transport is a highly fluctuating process. Our previous study (Ma et al., 2014) demonstrated a three-regime relation of the variance of bedload transport flux across a wide range of sampling time scales. This study further explored the fluctuation spectrum of at-a-point bedload transport flux with different sampling times. We derived out analytical solutions of the third- and fourth-order moments of bedload transport flux, based on a physically-based formulation (Ancey et al., 2008; Ma et al., 2014). A formulation of the probability density function of bedload transport flux was constructed based on the 1st through 4th order moments. Experimental data were used to test against the solutions of both the moments and PDF. Interestingly, the higher order statistical moments were found to exhibit the three-regime pattern as well. This study contributes to a comprehensive understanding of bedload transport flux fluctuation and emphasizes its timescale-dependent features resulting from the discrete nature and correlated motion of bedload material. The correlated structures of bedload transport, such as bed forms and particle clusters, deserve to be further exploration in future studies. Keywords: bedload transport; stochastic theory; high order moment; fluctuation; time scale; PDF. Ancey, C., Davison, A. C., Bohm, T., Jodeau, M., and Frey, P. Entrainment and motion of coarse particles in a shallow water stream down a steep slope, Journal of Fluid Mechanics, 2008, 595, 83-114, doi: 10.1017/S0022112007008774. Ma, H. B., Heyman, J., Fu, X. D., Mettra, F., Ancey, C. and Parker, G. Bedload transport over a broad range of time scales: determination of three regimes of fluctuations. Journal of Geophysical Research-Earth Surface, 2014. (under review)

  16. 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

  17. Fluxes of nitrous oxide and carbon dioxide over four potential biofuel crops in Central Illinois

    Science.gov (United States)

    Zeri, M.; Hickman, G. C.; Bernacchi, C.

    2009-12-01

    Nitrous oxide (N2O) and carbon dioxide (CO2) are important greenhouse gases that contribute to global climate change. Agriculture is a significant source of N2O to the atmosphere due to the use of nitrogen-based fertilizers. Fluxes of N2O and CO2 are measured using the flux-gradient technique over four different crops at the Energy Farm, a University of Illinois research facility in Urbana, Illinois. Measurements started in June of 2009 and are part of a project that aims to assess the impacts of potential biofuel crops on the carbon, water and nitrogen cycles. The species chosen are Maize (Zea mays), Miscanthus (Miscanthus x giganteus), Switchgrass (Panicum virgatum) and Prairie (a mix of several native species). The choice of species was based on their potential for the production of second-generation biofuels, i.e., fuels derived from the decomposition of the cellulosic material in the plant biomass. The use of corn residue for cellulosic biofuels might impact the carbon cycle through the reduction of soil organic content. Miscanthus is a perennial grass with great potential for biomass production. However, the total water used during the growing season and its water use efficiency might impose limits on the regions where this biofuel crop can be sustainably planted on a large scale. Switchgrass and the prairie species are less productive but might be suited for being well adapted and easy to establish. This study is the first side-by-side comparison of fluxes of N2O for these agro-ecosystems. The measurements are performed at micrometeorological towers placed at the center of 4 ha plots. The air is sampled at two heights over the vegetation and is analyzed in a tunable diode laser (TDL) installed nearby. A valve system cycles the TDL measurements trough all the intakes in the plots. The fluxes are calculated using the flux-gradient method, which requires the knowledge of the scalar vertical gradient as well as of the friction velocity (u*) and the Monin

  18. Survival of Flux Transfer Event (FTE) Flux Ropes Far Along the Tail Magnetopause

    Science.gov (United States)

    Eastwood, J. P.; Phan, T. D.; Fear, R. C.; Sibeck, D. G.; Angelopoulos, V.; Oieroset, M.; Shay, M. A.

    2012-01-01

    During intervals of southward IMF, magnetic reconnection can result in the formation of flux transfer events (FTEs) on the dayside magnetopause which travel along the magnetopause in the anti-sunward direction. Of particular interest is their fate and the role they play transporting solar wind plasma into the magnetosphere. We present the discovery of FTEs far along the distant tail magnetopause (x = 67 Earth radii) using data from ARTEMIS on the dusk flank magnetopause under southward/duskward IMF conditions. The identification of several events is further supported by excellent fits to a force-free flux rope model. The axis of each structure is principally north-south, i.e., perpendicular to the Sun-Earth line. Simultaneous observations by THEMIS on the dayside magnetopause indicate that FTEs are being produced there, although perhaps 2-4 times smaller in size. The convection time from the dayside magnetopause to ARTEMIS is 30 min, and the FTEs have a flux content comparable to those typically observed on the dayside magnetopause, indicating that these features are in quasi-equilibrium as they are convected downtail. By considering the relative orientations of the FTEs observed by THEMIS and ARTEMIS, the magnetic field geometry is consistent with the FTEs being produced on the dayside magnetopause along an extended X-line in the presence of IMF By and bending as they are convected to the flanks.

  19. FLUXNET. Database of fluxes, site characteristics, and flux-community information

    Energy Technology Data Exchange (ETDEWEB)

    Olson, R. J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holladay, S. K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cook, R. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Falge, E. [Univ. Bayreuth, Bayreuth (Germany); Baldocchi, D. [Univ. of California, Berkeley, CA (United States); Gu, L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2004-02-28

    FLUXNET is a “network of regional networks” created by international scientists to coordinate regional and global analysis of observations from micrometeorological tower sites. The flux tower sites use eddy covariance methods to measure the exchanges of carbon dioxide (CO2), water vapor, and energy between terrestrial ecosystems and the atmosphere. FLUXNET’S goals are to aid in understanding the mechanisms controlling the exchanges of CO2, water vapor, and energy across a range of time (0.5 hours to annual periods) and space scales. FLUXNET provides an infrastructure for the synthesis and analysis of world-wide, long-term flux data compiled from various regional flux networks. Information compiled by the FLUXNET project is being used to validate remote sensing products associated with the National Aeronautics and Space Administration (NASA) Terra and Aqua satellites. FLUXNET provides access to ground information for validating estimates of net primary productivity, and energy absorption that are being generated by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors. In addition, this information is also used to develop and validate ecosystem models.

  20. Emission Flux Measurement Error with a Mobile DOAS System and Application to NOx Flux Observations.

    Science.gov (United States)

    Wu, Fengcheng; Li, Ang; Xie, Pinhua; Chen, Hao; Hu, Zhaokun; Zhang, Qiong; Liu, Jianguo; Liu, Wenqing

    2017-01-25

    Mobile differential optical absorption spectroscopy (mobile DOAS) is an optical remote sensing method that can rapidly measure trace gas emission flux from air pollution sources (such as power plants, industrial areas, and cities) in real time. Generally, mobile DOAS is influenced by wind, drive velocity, and other factors, especially in the usage of wind field when the emission flux in a mobile DOAS system is observed. This paper presents a detailed error analysis and NOx emission with mobile DOAS system from a power plant in Shijiazhuang city, China. Comparison of the SO₂ emission flux from mobile DOAS observations with continuous emission monitoring system (CEMS) under different drive speeds and wind fields revealed that the optimal drive velocity is 30-40 km/h, and the wind field at plume height is selected when mobile DOAS observations are performed. In addition, the total errors of SO₂ and NO₂ emissions with mobile DOAS measurements are 32% and 30%, respectively, combined with the analysis of the uncertainties of column density, wind field, and drive velocity. Furthermore, the NOx emission of 0.15 ± 0.06 kg/s from the power plant is estimated, which is in good agreement with that from CEMS observations of 0.17 ± 0.07 kg/s. This study has significantly contributed to the measurement of the mobile DOAS system on emission from air pollution sources, thus improving estimation accuracy.