WorldWideScience

Sample records for modeling excess gas

  1. Conversion Excess Coal Gas to Dimethyl Ether in Steel Works

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    With the technical progress of metallurgical industry, more excess gas will be produced in steel works. The feasibility of producing dimethyl ether by gas synthesis was discussed, which focused on marketing, energy balance, process design, economic evaluation, and environmental protection etc. DME was considered to be a new way to utilize excess coal gas in steel works.

  2. Molecular simulation of excess isotherm and excess enthalpy change in gas-phase adsorption.

    Science.gov (United States)

    Do, D D; Do, H D; Nicholson, D

    2009-01-29

    We present a new approach to calculating excess isotherm and differential enthalpy of adsorption on surfaces or in confined spaces by the Monte Carlo molecular simulation method. The approach is very general and, most importantly, is unambiguous in its application to any configuration of solid structure (crystalline, graphite layer or disordered porous glass), to any type of fluid (simple or complex molecule), and to any operating conditions (subcritical or supercritical). The behavior of the adsorbed phase is studied using the partial molar energy of the simulation box. However, to characterize adsorption for comparison with experimental data, the isotherm is best described by the excess amount, and the enthalpy of adsorption is defined as the change in the total enthalpy of the simulation box with the change in the excess amount, keeping the total number (gas + adsorbed phases) constant. The excess quantities (capacity and energy) require a choice of a reference gaseous phase, which is defined as the adsorptive gas phase occupying the accessible volume and having a density equal to the bulk gas density. The accessible volume is defined as the mean volume space accessible to the center of mass of the adsorbate under consideration. With this choice, the excess isotherm passes through a maximum but always remains positive. This is in stark contrast to the literature where helium void volume is used (which is always greater than the accessible volume) and the resulting excess can be negative. Our definition of enthalpy change is equivalent to the difference between the partial molar enthalpy of the gas phase and the partial molar enthalpy of the adsorbed phase. There is no need to assume ideal gas or negligible molar volume of the adsorbed phase as is traditionally done in the literature. We illustrate this new approach with adsorption of argon, nitrogen, and carbon dioxide under subcritical and supercritical conditions.

  3. Minimal Dilaton Model and the Diphoton Excess

    CERN Document Server

    Agarwal, Bakul; Mohan, Kirtimaan A

    2016-01-01

    In light of the recent 750 GeV diphoton excesses reported by the ATLAS and CMS collaborations, we investigate the possibility of explaining this excess using the Minimal Dilaton Model. We find that this model is able to explain the observed excess with the presence of additional top partner(s), with same charge as the top quark, but with mass in the TeV region. First, we constrain model parameters using in addition to the 750 GeV diphoton signal strength, precision electroweak tests, single top production measurements, as well as Higgs signal strength data collected in the earlier runs of the LHC. In addition we discuss interesting phenomenolgy that could arise in this model, relevant for future runs of the LHC.

  4. Infrared Excess and Molecular Gas in Galactic Supershells

    CERN Document Server

    Lee, J E; Koo, B C; Lee, Jeong-Eun; Kim, Kee-Tae; Koo, Bon-Chul

    1999-01-01

    We have carried out high-resolution observations along one-dimensional cuts through the three Galactic supershells GS 064-01-97, GS 090-28-17, and GS 174+02-64 in the HI 21 cm and CO J=1-0 lines. By comparing the HI data with IRAS data, we have derived the distributions of the I_100 and tau_100 excesses, which are, respectively, the 100 mum intensity and 100 mum optical depth in excess of what would be expected from HI emission. We have found that both the I_100 and tau_100 excesses have good correlations with the CO integrated intensity W_CO in all three supershells. But the I_100 excess appears to underestimate H_2 column density N(H_2) by factors of 1.5-3.8. This factor is the ratio of atomic to molecular infrared emissivities, and we show that it can be roughly determined from the HI and IRAS data. By comparing the tau_100 excess with W_CO, we derive the conversion factor X = N(H_2)/W_CO = 0.26-0.66 in the three supershells. In GS 090-28-17, which is a very diffuse shell, our result suggests that the regi...

  5. Central gas entropy excess as direct evidence for AGN feedback in galaxy groups and clusters

    Institute of Scientific and Technical Information of China (English)

    Yu Wang; Hai-Guang Xu; Jun-Hua Gu; Li-Yi Gu; Jing-Ying Wang; Zhong-Li Zhang

    2010-01-01

    By analyzing Chandra X-ray data of a sample of 21 galaxy groups and 19galaxy clusters,we find that in 31 sample systems there exists a significant central(R ≤10h-171 kpc)gas entropy excess(△K0),which corresponds to(=)0.1-0.5 keV per gas particle,beyond the power-law model that best fits the radial entropy profile of the outer regions.We also find a distinct correlation between the central entropy excess△K0 and K-band luminosity LK of the central dominating galaxies(CDGs),which is scaled as △K0 ∝ L1.6±0.4K,where LK is tightly associated with the mass of the supermassive black hole hosted in the CDG.In fact,if an effective mass-to-energy conversion-efficiency of 0.02 is assumed for the accretion process,the cumulative AGN feedback EAGNfeedback(=)ηMBHC2 yields an extra heating of(=)0.5-17.0keV per particle,which feedback is sufficient to explain the central entropy excess.In most cases,the AGN contribution can compensate the radiative loss of the X-ray gas within the cooling radius((=)0.002-2.2 keV per particle),and apparently exceeds the energy required to cause the scaling relations to deviate from the self-similar predictions((=)0.2-1.0 keV per particle).In contrast to the AGN feedback,the extra heating provided by supernova explosions accounts for(=)0.01-0.08 keV per particle in groups and is almost negligible in clusters.Therefore,the observed correlation between ΔK0 and LK can be considered as direct evidence for AGN feedback in galaxy groups and clusters.

  6. A model for the LHC diboson excess

    CERN Document Server

    Buen-Abad, Manuel; Schmaltz, Martin

    2016-01-01

    The first run of the LHC showed hints of a new resonance with mass near $1.9$ TeV decaying into electroweak gauge boson pairs as well as into dijets. While Run 2 has neither confirmed nor ruled out such a resonance, it has yielded new constraints on models attempting to explain these decays. Additionally in $W'$ models where this new resonance is a charged vector boson that is a weak isospin singlet there is the potential for conflict with the electroweak precision $T$ parameter. We construct variants of a $W'$ resonance model that provide an excellent fit to both Run 1 and Run 2 data, as well as electroweak precision measurements. The model also predicts a neutral vector boson, a $Z'$, with mass close to $3$ TeV. This $Z'$ is compatible with the intriguing Run 2 observation of a dielectron pair with invariant mass of $2.9$ TeV at CMS.

  7. World Natural Gas Model

    Energy Technology Data Exchange (ETDEWEB)

    1994-12-01

    RAMSGAS, the Research and Development Analysis Modeling System World Natural Gas Model, was developed to support planning of unconventional gaseoues fuels research and development. The model is a scenario analysis tool that can simulate the penetration of unconventional gas into world markets for oil and gas. Given a set of parameter values, the model estimates the natural gas supply and demand for the world for the period from 1980 to 2030. RAMSGAS is based on a supply/demand framwork and also accounts for the non-renewable nature of gas resources. The model has three fundamental components: a demand module, a wellhead production cost module, and a supply/demand interface module. The demand for gas is a product of total demand for oil and gas in each of 9 demand regions and the gas share. Demand for oil and gas is forecast from the base year of 1980 through 2030 for each demand region, based on energy growth rates and price-induced conservation. For each of 11 conventional and 19 unconventional gas supply regions, wellhead production costs are calculated. To these are added transportation and distribution costs estimates associated with moving gas from the supply region to each of the demand regions and any economic rents. Based on a weighted average of these costs and the world price of oil, fuel shares for gas and oil are computed for each demand region. The gas demand is the gas fuel share multiplied by the total demand for oil plus gas. This demand is then met from the available supply regions in inverse proportion to the cost of gas from each region. The user has almost complete control over the cost estimates for each unconventional gas source in each year and thus can compare contributions from unconventional resources under different cost/price/demand scenarios.

  8. Asymmetric Dark Matter Models and the LHC Diphoton Excess

    DEFF Research Database (Denmark)

    Frandsen, Mads T.; Shoemaker, Ian M.

    2016-01-01

    The existence of dark matter (DM) and the origin of the baryon asymmetry are persistent indications that the SM is incomplete. More recently, the ATLAS and CMS experiments have observed an excess of diphoton events with invariant mass of about 750 GeV. One interpretation of this excess is decays...... have for models of asymmetric DM that attempt to account for the similarity of the dark and visible matter abundances....

  9. Asymmetric Dark Matter Models and the LHC Diphoton Excess

    DEFF Research Database (Denmark)

    Frandsen, Mads T.; Shoemaker, Ian M.

    2016-01-01

    The existence of dark matter (DM) and the origin of the baryon asymmetry are persistent indications that the SM is incomplete. More recently, the ATLAS and CMS experiments have observed an excess of diphoton events with invariant mass of about 750 GeV. One interpretation of this excess is decays...... have for models of asymmetric DM that attempt to account for the similarity of the dark and visible matter abundances....

  10. Gamma-Ray Excess and the Minimal Dark Matter Model

    CERN Document Server

    Duerr, Michael; Smirnov, Juri

    2015-01-01

    We point out that the gamma-ray excesses in the galactic center and in the dwarf galaxy Reticulum II can both be well explained within the simplest dark matter model. We find that the corresponding region of parameter space will be tested by direct and indirect dark matter searches in the near future.

  11. ATLAS diboson excesses from the stealth doublet model

    Directory of Open Access Journals (Sweden)

    Wei Chao

    2016-02-01

    Full Text Available The ATLAS Collaboration has reported excesses in diboson invariant mass searches of new resonances around 2 TeV, which might be a prediction of new physics around that mass range. We interpret these results in the context of a modified stealth doublet model where the extra Higgs doublet has a Yukawa interaction with the first generation quarks, and show that the heavy CP-even Higgs boson can naturally explain the excesses in the WW and ZZ channels with a small Yukawa coupling, ξ∼0.15, and a tiny mixing angle with the SM Higgs boson, α∼0.05. Furthermore, the model satisfies constraints from colliders and electroweak precision measurements.

  12. Novel Diagnostic Model for the Deficient and Excess Pulse Qualities

    Directory of Open Access Journals (Sweden)

    Jaeuk U. Kim

    2012-01-01

    Full Text Available The deficient and excess pulse qualities (DEPs are the two representatives of the deficiency and excess syndromes, respectively. Despite its importance in the objectification of pulse diagnosis, a reliable classification model for the DEPs has not been reported to date. In this work, we propose a classification method for the DEPs based on a clinical study. First, through factor analysis and Fisher's discriminant analysis, we show that all the pulse amplitudes obtained at various applied pressures at Chon, Gwan, and Cheok contribute on equal orders of magnitude in the determination of the DEPs. Then, we discuss that the pulse pressure or the average pulse amplitude is appropriate for describing the collective behaviors of the pulse amplitudes and a simple and reliable classification can be constructed from either quantity. Finally, we propose an enhanced classification model that combines the two complementary variables sequentially.

  13. Background model systematics for the Fermi GeV excess

    CERN Document Server

    Calore, Francesca; Weniger, Christoph

    2014-01-01

    The possible gamma-ray excess in the inner Galaxy and the Galactic center (GC) suggested by Fermi-LAT observations has triggered a large number of studies. It has been interpreted as a variety of different phenomena such as a signal from WIMP dark matter annihilation, gamma-ray emission from a population of millisecond pulsars, or emission from cosmic rays injected in a sequence of burst-like events or continuously at the GC. We present the first comprehensive study of model systematics coming from the Galactic diffuse emission in the inner part of our Galaxy and their impact on the inferred properties of the excess emission at Galactic latitudes $2^\\circ<|b|<20^\\circ$ and 300 MeV to 500 GeV. We study both theoretical and empirical model systematics, which we deduce from a large range of Galactic diffuse emission models and a principal component analysis of residuals in numerous test regions along the Galactic plane. We show that the hypothesis of an extended spherical excess emission with a uniform ene...

  14. Dietary treatment of colic caused by excess gas in infants: Biochemical evidence

    Institute of Scientific and Technical Information of China (English)

    Dámaso Infante; Oscar Segarra; Bernard Le Luyer

    2011-01-01

    AIM: To evaluate the impact of feeding colicky infants with an adapted formula on the hydrogen breath test and clinical symptoms. METHODS: Hydrogen expiration was measured by SC MicroLyzer gas chromatography at inclusion and 15 d after treatment with an adapted low-lactose formula in 20 colicky infants. RESULTS: All babies were symptomatic: 85% with excess gas, 75% with abnormal feeding pattern, and 85% with excessive crying. The hydrogen breath test at inclusion was abnormal: 35 ± 3.1 ppm. After 15 d feeding with an adapted low-lactose formula, crying and flatulence decreased in 85% of patients (P < 0.001). For infants in whom no decrease of gas was reported, crying was still reduced (P < 0.01). Moreover, the feeding pattern was improved in 50% of infants when it was initially considered as abnormal. Finally, the hydrogen breath test decreased significantly (10 ± 2.5 ppm, P < 0.01). CONCLUSION: This study showed an association between clinical improvement and evidence of decreased levels of hydrogen when the infants were fed with a specially designed, low-lactose formula.

  15. The di-photon excess in a perturbative SUSY model

    Science.gov (United States)

    Benakli, Karim; Darmé, Luc; Goodsell, Mark D.; Harz, Julia

    2016-10-01

    We show that a 750 GeV di-photon excess as reported by the ATLAS and CMS experiments can be reproduced by the Minimal Dirac Gaugino Supersymmetric Standard Model (MDGSSM) without the need of any ad-hoc addition of new states. The scalar resonance is identified with the spin-0 partner of the Dirac bino. We perform a thorough analysis of constraints coming from the mixing of the scalar with the Higgs boson, the stability of the vacuum and the requirement of perturbativity of the couplings up to very high energy scales. We exhibit examples of regions of the parameter space that respect all the constraints while reproducing the excess. We point out how trilinear couplings that are expected to arise in supersymmetry-breaking mediation scenarios, but were ignored in the previous literature on the subject, play an important role.

  16. The di-photon excess in a perturbative SUSY model

    Energy Technology Data Exchange (ETDEWEB)

    Benakli, Karim, E-mail: kbenakli@lpthe.jussieu.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7589, LPTHE, F-75005, Paris (France); CNRS, UMR 7589, LPTHE, F-75005, Paris (France); Darmé, Luc, E-mail: darme@lpthe.jussieu.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7589, LPTHE, F-75005, Paris (France); CNRS, UMR 7589, LPTHE, F-75005, Paris (France); Sorbonne Universités, Institut Lagrange de Paris (ILP), 98 bis Boulevard Arago, 75014 Paris (France); Goodsell, Mark D., E-mail: goodsell@lpthe.jussieu.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7589, LPTHE, F-75005, Paris (France); CNRS, UMR 7589, LPTHE, F-75005, Paris (France); Harz, Julia, E-mail: jharz@lpthe.jussieu.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7589, LPTHE, F-75005, Paris (France); CNRS, UMR 7589, LPTHE, F-75005, Paris (France); Sorbonne Universités, Institut Lagrange de Paris (ILP), 98 bis Boulevard Arago, 75014 Paris (France)

    2016-10-15

    We show that a 750 GeV di-photon excess as reported by the ATLAS and CMS experiments can be reproduced by the Minimal Dirac Gaugino Supersymmetric Standard Model (MDGSSM) without the need of any ad-hoc addition of new states. The scalar resonance is identified with the spin-0 partner of the Dirac bino. We perform a thorough analysis of constraints coming from the mixing of the scalar with the Higgs boson, the stability of the vacuum and the requirement of perturbativity of the couplings up to very high energy scales. We exhibit examples of regions of the parameter space that respect all the constraints while reproducing the excess. We point out how trilinear couplings that are expected to arise in supersymmetry-breaking mediation scenarios, but were ignored in the previous literature on the subject, play an important role.

  17. The Di-Photon Excess in a Perturbative SUSY Model

    CERN Document Server

    Benakli, Karim; Goodsell, Mark D; Harz, Julia

    2016-01-01

    We show that a 750 GeV di-photon excess as reported by the ATLAS and CMS experiments can be reproduced by the Minimal Dirac Gaugino Supersymmetric Standard Model (MDGSSM) without the need of any ad-hoc addition of new states. The scalar resonance is identified with the spin-0 partner of the Dirac bino. We perform a thorough analysis of constraints coming from the mixing of the scalar with the Higgs boson, the stability of the vacuum and the requirement of perturbativity of the couplings up to very high energy scales. We exhibit examples of regions of the parameter space that respect all the constraints while reproducing the excess. We point out how trilinear couplings that are expected to arise in supersymmetry-breaking mediation scenarios, but were ignored in the previous literature on the subject, play an important role.

  18. Background model systematics for the Fermi GeV excess

    Energy Technology Data Exchange (ETDEWEB)

    Calore, Francesca; Cholis, Ilias; Weniger, Christoph

    2015-03-01

    The possible gamma-ray excess in the inner Galaxy and the Galactic center (GC) suggested by Fermi-LAT observations has triggered a large number of studies. It has been interpreted as a variety of different phenomena such as a signal from WIMP dark matter annihilation, gamma-ray emission from a population of millisecond pulsars, or emission from cosmic rays injected in a sequence of burst-like events or continuously at the GC. We present the first comprehensive study of model systematics coming from the Galactic diffuse emission in the inner part of our Galaxy and their impact on the inferred properties of the excess emission at Galactic latitudes 2° < |b| < 20° and 300 MeV to 500 GeV. We study both theoretical and empirical model systematics, which we deduce from a large range of Galactic diffuse emission models and a principal component analysis of residuals in numerous test regions along the Galactic plane. We show that the hypothesis of an extended spherical excess emission with a uniform energy spectrum is compatible with the Fermi-LAT data in our region of interest at 95% CL. Assuming that this excess is the extended counterpart of the one seen in the inner few degrees of the Galaxy, we derive a lower limit of 10.0° (95% CL) on its extension away from the GC. We show that, in light of the large correlated uncertainties that affect the subtraction of the Galactic diffuse emission in the relevant regions, the energy spectrum of the excess is equally compatible with both a simple broken power-law of break energy E(break) = 2.1 ± 0.2 GeV, and with spectra predicted by the self-annihilation of dark matter, implying in the case of bar bb final states a dark matter mass of m(χ)=49(+6.4)(-)(5.4)  GeV.

  19. The Illusive ISM of Dwarf Galaxies: Excess Submillimetre Emission and CO-Dark Molecular Gas

    CERN Document Server

    Madden, Suzanne C; Cormier, Diane; Lebouteiller, Vianney; Galliano, Frederic; Hony, Sacha; Remy, Aurelie; Sauvage, Marc; Contursi, Alessandra; Sturm, Eckhard; Poglitsch, Albrecht; Pohlen, Michael; Smith, M W L; Bendo, George; O'Halloran, Brian; 2, The SPIRE SAG; consortia., PACS

    2011-01-01

    The Herschel Dwarf Galaxy Survey investigates the interplay of star formation activity and the the metal-poor gas and dust of dwarf galaxies using FIR and submillimetre imaging spectroscopic and photometric observations in the 50 to 550mu window of the Herschel Space Observatory. The dust SEDs are well constrained with the new Herschel and MIR Spitzer data. A submillimetre excess is often found in low metallicity galaxies, which,if tracing very cold dust, would highlight large dust masses not easily reconciled in some cases, given the low metallicities and expected gas-to-dust mass ratios. The galaxies are also mapped in the FIR fine-structure lines (63 and 145mu OI, 158mu CII, 122 and 205mu NII, 88mu OIII) probing the low density ionised gas, the HII regions and photodissociation regions. While still early in the Herschel mission we can already see, along with earlier studies, that line ratios in the metal-poor ISM differ remarkably from those in the metal-rich starburst environments. In dwarf galaxies, L[CI...

  20. WHIM emission and the cluster soft excess: a model comparison

    CERN Document Server

    Mittaz, J; Cen, R; Bonamente, M

    2004-01-01

    The confirmation of the cluster soft excess (CSE) by XMM-Newton has rekindled interest as to its origin. The recent detections of CSE emission at large cluster radii together with reports of OVII line emission associated with the CSE has led many authors to conjecture that the CSE is, in fact, a signature of the warm-hot intergalactic medium (WHIM). In this paper we test the scenario by comparing the observed properties of the CSE with predictions based on models of the WHIM. We find that emission from the WHIM in current models is 3 to 4 orders of magnitude too faint to explain the CSE. We discuss different possibilities for this discrepancy including issues of simulation resolution and scale, and the role of small density enhancements or galaxy groups. Our final conclusion is that the WHIM alone is unlikely to be able to accout for the observed flux of the CSE.

  1. A spartan model for the LHC diphoton excess

    CERN Document Server

    Appelquist, Thomas; Piai, Maurizio; Thompson, Jedidah

    2016-01-01

    We propose a simple model accommodating the reported 750 GeV diphoton excess seen in the first 13-TeV run of the LHC. It leads to testable predictions, in particular for di-lepton production, at higher integrated luminosity. We append to the minimal standard model a new gauge sector with its own SU(2) symmetry group. A new complex doublet scalar field provides mass for the new vectors and describes the 750-GeV resonance. An adequate rate for the diphoton signals, with resonant production via photon fusion, requires the VEV of the new scalar field to be somewhat less than the electroweak scale. This in turn requires the new heavy vectors to have sub-TeV masses and be strongly coupled. A new global U(1) symmetry plays a key role. Current precision-electroweak constraints are respected.

  2. New studies on molecular chirality in the gas phase: enantiomer differentiation and determination of enantiomeric excess.

    Science.gov (United States)

    Patterson, David; Schnell, Melanie

    2014-06-21

    Chirality plays a fundamental role in the activity of biological molecules and broad classes of chemical reactions. The chemistry of life is built almost exclusively on left-handed amino acids and right-handed sugars, a phenomenon known as "homochirality of life". Furthermore, most drugs developed in the last decade are of specified chirality. Thus, fast and reliable methods that can differentiate molecules of different handedness, determine the enantiomeric excess of even molecular mixtures, and allow for an unambiguous determination of molecular handedness are of great interest, in particular with respect to complex mixtures. In this perspective article, we discuss the recent developments, with an emphasis on modern spectroscopic methods using gas-phase samples, such as photoelectron circular dichroism, Coulomb explosion imaging, and microwave three-wave mixing.

  3. Studying the entropy excess and entropy excess ratio in (105,106,107)Pd within BCS model

    CERN Document Server

    Rahmatinejad, Azam; Razavi, Rohallah

    2015-01-01

    Pairing correlations and their influence on nuclear properties has been studied within BCS model. Using this theoretical model with inclusion of pairing interaction between nucleons, nuclear level density and entropy of Pd(105,106,107) have been extracted. The results well coincide with the empirical values of the nuclear level densities obtained by Oslo group. Then the entropy excess of Pd107 and Pd105 compared to Pd106 as a function of the temperature has been studied. Also the role of neutron and proton system in entropy excess have been investigated by the using of the entropy excess ratio proposed by Razavi et al. [R. Razavi, A.N. Behkami, S. Mohammadi, and M. Gholami, Phys. Rev. C 86, 047303 (2012)].

  4. Excess C/O and C/H in outer protoplanetary disk gas

    CERN Document Server

    Oberg, Karin I

    2016-01-01

    The compositions of nascent planets depend on the compositions of their birth disks. In particular, the elemental compositions of Gas Giant gaseous envelopes depend on the elemental composition of the disk gas from which the envelope is accreted. Previous models demonstrated that sequential freeze-out of O and C-bearing volatiles in disks will result in an supersolar C/O ratios and subsolar C/H ratios in the gas between water and CO snowlines. This result does not take into account, however, the expected grain growth and radial drift of pebbles in disks, and the accompanying re-distribution of volatiles from the outer to the inner disk. Using a toy model we demonstrate that when drift is considered, CO is enhanced between the water and CO snowline, resulting in both supersolar C/O and C/H ratios in the disk gas in the Gas Giant formation zone. This result appears robust to the details of the disk model as long as there is substantial pebble drift across the CO snowline, and the efficiency of CO vapor diffusio...

  5. Towards a Multi-Model Subseasonal Excessive Heat Outlook System

    Science.gov (United States)

    Vintzileos, A.

    2015-12-01

    We developed an experimental realtime subseasonal excessive heat outlook and monitoring system (SEHOMS) based on the detection of heat events in dynamical forecasts and reanalyses. Our definition of a heat event takes into account both the challenges of subseasonal forecasting and the effects of heat stress on human physiology e.g., the dependence of heat impacts on duration, geographical location and timing of the heat event. The prototype outlook system focuses on forecast lead time week-2 and uses the Global Ensemble Forecast System (GEFS) reforecast conducted at ESRL and the NCEP-GEFS operational realtime ensemble forecasts. The prototype monitoring system, on which we base forecast verification, provides a dual output. The first product uses the NCAR/NCEP reanalysis; the second monitoring product is based on the day-1 forecast from the GEFS reforecast and from the operational GEFS realtime forecast. In this presentation we first show results from the prototype forecasting and monitoring system. We then compare these results with forecasts from the SEHOMS in which we gradually add reforecasts obtained from the S2S database (NCEP - Climate forecast System and ECMWF models). Finally we discuss the possibility of expanding the SEHOMS to week-3 and week-4 based on results from the CFS, ECMWF model, and the North American Multi-Model Ensemble system (NMME).

  6. Methodology to determine the appropriate amount of excess air for the operation of a gas turbine in a wet environment

    Energy Technology Data Exchange (ETDEWEB)

    Lugo-Leyte, R.; Zamora-Mata, J.M.; Torres-Aldaco, A. [Universidad Autonoma Metropolitana-Iztapalapa, Departamento de Ingenieria de Procesos e Hidraulica, San Rafael Atlixco 186, Col Vicentina 09340, Iztapalapa, Mexico, D.F. (Mexico); Toledo-Velazquez, M. [Instituto Politecnico Nacional, Escuela Superior de Ingenieria Mecanica y Electrica, Seccion de Estudios de Posgrado e Investigacion, Laboratorio de Ingenieria Termica e Hidraulica Aplicada, Unidad Profesional Adolfo Lopez Mateos, Edificio 5, 3er piso SEPI-ESIME, C.P. 07738, Col. Lindavista, Mexico D.F. (Mexico); Salazar-Pereyra, M. [Tecnologico de Estudios Superiores de Ecatepec, Division de Ingenieria Mecatronica e Industrial, Posgrado en Ciencias en Ingenieria Mecatronica, Av. Tecnologico s/n, Col. Valle de Anahuac, C.P. 55210, Ecatepec de Morelos, Estado de Mexico (Mexico)

    2010-02-15

    This paper addresses the impact of excess air on turbine inlet temperature, power, and thermal efficiency at different pressure ratios. An explicit relationship is developed to determine the turbine inlet temperature as a function of excess air, pressure ratio and relative humidity. The effect of humidity on the calculation of excess air to achieve a pre-established power output is analyzed and presented. Likewise it is demonstrated that dry air calculations provide a valid upper bound for the performance of a gas turbine under a wet environment. (author)

  7. Composition and Temperature Dependence of Excess Volume of Heavy Oil-Stocks Mixtures + (Gas oil or Toluene or Reformate

    Directory of Open Access Journals (Sweden)

    Shahad Z. Atta

    2011-01-01

    Full Text Available Binary mixtures of three, heavy oil-stocks was subjected to density measurements at temperatures of 30, 35 and 40 °C. and precise data was acquired on the volumetric behavior of these systems. The results are reported in terms of equations for excess specific volumes of mixtures. The heavy oil-stocks used were of good varity, namely 40 stock, 60 stock, and 150 stock. The lightest one is 40 stock with API gravity 33.69 while 60 stock is a middle type and 150 stock is a heavy one, with API gravity 27.74 and 23.79 respectively. Temperatures in the range of 30-40 °C have a minor effect on excess volume of heavy oil-stock binary mixture thus, insignificant expansion or shrinkage is observed by increasing the temperature this effect becomes more significant although the heavy oil-stocks is spiked with hydrocarbons like (gas oil, toluene and reformate. Blending of Heavy oil-stocks with hydrocarbons spikes (gas oil, toluene and reformate form non-ideal mixtures, for which excess volume can be positive or negative depending on nature species. Spiking of Heavy oil-stocks with either gas oil or reformate resulted in negative excess volume. This shrinkage is greater for the lowest boiling point spike as in the case of reformate, While, the presence of methyl groups in aromatic rings results in a positive excess volume, as shown in toluene when blended with 40 stock but a negative excess volume was found when blended with 60 stock and 150 stock. The API gravity of heavy oil-stocks has an effect on excess volume when the oil-stocks spiked with hydrocarbons like (gas oil, toluene and reformate. This 40 stocks as a typical light types resulted in minimum negative excess volume of -0.47 at 30 °C, when it was spiked with the gas oil; while the spiked heavy oil-stock with kerosene shows a maximum excess volume of -15.56 at 40 °C.

  8. X-ray Cavities in Galaxy Groups and Clusters: Central Gas Entropy Excess as Direct Evidence for AGN Feedback

    Indian Academy of Sciences (India)

    Yu Wang

    2011-03-01

    Observations of X-ray jets and cavities in clusters of galaxies observed by Chandra are briefly reviewed. A recent study on the excess of central gas entropy, which can be considered as direct evidence for AGN feedback in galaxy groups and clusters is presented. An expanded account of this study has been presented in RAA (Wang et al. 2010).

  9. Background model systematics for the Fermi GeV excess

    NARCIS (Netherlands)

    Calore, F.; Cholis, I.; Weniger, C.

    2015-01-01

    The possible gamma-ray excess in the inner Galaxy and the Galactic center (GC) suggested by Fermi-LAT observations has triggered a large number of studies. It has been interpreted as a variety of different phenomena such as a signal from WIMP dark matter annihilation, gamma-ray emission from a popul

  10. Decision model for evaluating reactor disposition of excess plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Edmunds, T.

    1995-02-01

    The US Department of Energy is currently considering a range of technologies for disposition of excess weapon plutonium. Use of plutonium fuel in fission reactors to generate spent fuel is one class of technology options. This report describes the inputs and results of decision analyses conducted to evaluate four evolutionary/advanced and three existing fission reactor designs for plutonium disposition. The evaluation incorporates multiple objectives or decision criteria, and accounts for uncertainty. The purpose of the study is to identify important and discriminating decision criteria, and to identify combinations of value judgments and assumptions that tend to favor one reactor design over another.

  11. DUST AND GAS IN THE MAGELLANIC CLOUDS FROM THE HERITAGE HERSCHEL KEY PROJECT. I. DUST PROPERTIES AND INSIGHTS INTO THE ORIGIN OF THE SUBMILLIMETER EXCESS EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, Karl D.; Roman-Duval, Julia; Meixner, Margaret [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bot, Caroline [Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l Université, F-67000 Strasbourg (France); Babler, Brian [Department of Astronomy, 475 North Charter Street, University of Wisconsin, Madison, WI 53706 (United States); Bernard, Jean-Philippe [CESR, Université de Toulouse, UPS, 9 Avenue du Colonel Roche, F-31028 Toulouse, Cedex 4 (France); Bolatto, Alberto; Jameson, Katherine [Department of Astronomy, Lab for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Boyer, Martha L. [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Clayton, Geoffrey C. [Department of Physics and Astronomy, Louisiana State University, 233-A Nicholson Hall, Tower Drive, Baton Rouge, LA 70803 (United States); Engelbracht, Charles [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Fukui, Yasuo [Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan); Galametz, Maud [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching-bei-Mnchen (Germany); Galliano, Frederic; Hony, Sacha; Lebouteiller, Vianney [CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Hughes, Annie [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Indebetouw, Remy [Department of Astronomy, University of Virginia, and National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Israel, Frank P. [Sterrewacht Leiden, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Kawamura, Akiko [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo, 181-8588 (Japan); and others

    2014-12-20

    The dust properties in the Large and Small Magellanic clouds (LMC/SMC) are studied using the HERITAGE Herschel Key Project photometric data in five bands from 100 to 500 μm. Three simple models of dust emission were fit to the observations: a single temperature blackbody modified by a power-law emissivity (SMBB), a single temperature blackbody modified by a broken power-law emissivity (BEMBB), and two blackbodies with different temperatures, both modified by the same power-law emissivity (TTMBB). Using these models, we investigate the origin of the submillimeter excess, defined as the submillimeter emission above that expected from SMBB models fit to observations <200 μm. We find that the BEMBB model produces the lowest fit residuals with pixel-averaged 500 μm submillimeter excesses of 27% and 43% for the LMC and SMC, respectively. Adopting gas masses from previous works, the gas-to-dust ratios calculated from our fitting results show that the TTMBB fits require significantly more dust than are available even if all the metals present in the interstellar medium (ISM) were condensed into dust. This indicates that the submillimeter excess is more likely to be due to emissivity variations than a second population of colder dust. We derive integrated dust masses of (7.3 ± 1.7) × 10{sup 5} and (8.3 ± 2.1) × 10{sup 4} M {sub ☉} for the LMC and SMC, respectively. We find significant correlations between the submillimeter excess and other dust properties; further work is needed to determine the relative contributions of fitting noise and ISM physics to the correlations.

  12. Overconsumption of Energy and Excessive Discretionary Food Intake Inflates Dietary Greenhouse Gas Emissions in Australia

    Directory of Open Access Journals (Sweden)

    Gilly A. Hendrie

    2016-10-01

    Full Text Available Population dietary guidelines have started to include information about the environmental impacts of food choices, but more quantifiable evidence is needed, particularly about the impacts associated with discretionary foods. This paper utilised the 2011–2012 Australian Health Survey food intake data along with a highly disaggregated input–output model to estimate the greenhouse gas emissions (GHGe of Australians’ dietary intake, and compare current patterns of eating which vary in diet quality and GHGe to the recommended diet. The average dietary GHGe were 18.72 ± 12.06 and 13.73 ± 8.72 kg CO2e/day for male and female adults, respectively. The correlation between total energy and GHGe was r = 0.54 (p < 0.001. Core foods contributed 68.4% and discretionary foods 29.4%. Within core foods, fresh meat and alternatives (33.9% was the greatest contributor. The modelling of current dietary patterns showed the contribution of discretionary foods to GHGe was 121% greater in the average diet and 307% greater in the “lower quality, higher GHGe” diet compared to the recommended diet. Reducing discretionary food intake would allow for small increases in emissions from core foods (in particular vegetables, dairy and grains, thereby providing a nutritional benefit at little environmental expense. Public health messages that promote healthy eating, eating to one’s energy needs and improved diet quality will also contribute to lowering GHGe.

  13. Gas Turbine Engine Behavioral Modeling

    OpenAIRE

    Meyer, Richard T; DeCarlo, Raymond A.; Pekarek, Steve; Doktorcik, Chris

    2014-01-01

    This paper develops and validates a power flow behavioral model of a gas tur- bine engine with a gas generator and free power turbine. “Simple” mathematical expressions to describe the engine’s power flow are derived from an understand- ing of basic thermodynamic and mechanical interactions taking place within the engine. The engine behavioral model presented is suitable for developing a supervisory level controller of an electrical power system that contains the en- gine connected to a gener...

  14. Dust and Gas in the Magellanic Clouds from the HERITAGE Herschel Key Project. I. Dust Properties and Insights into the Origin of the Submm Excess Emission

    CERN Document Server

    Gordon, Karl D; Bot, Caroline; Meixner, Margaret; Babler, Brian; Bernard, Jean-Philippe; Bolatto, Alberto; Boyer, Martha L; Clayton, Geoffrey C; Engelbracht, Charles; Fukui, Yasuo; Galametz, Maud; Galliano, Frederic; Hony, Sacha; Hughes, Annie; Indebetouw, Remy; Israel, Frank P; Jameson, Katie; Kawamura, Akiko; Lebouteiller, Vianney; Li, Aigen; Madden, Suzanne C; Matsuura, Mikako; Misselt, Karl; Montiel, Edward; Okumura, K; Onishi, Toshikazu; Panuzzo, Pasquale; Paradis, Deborah; Rubio, Monica; Sandstrom, Karin; Sauvage, Marc; Seale, Jonathan; Sewilo, Marta; Tchernyshyov, Kirill; Skibba, Ramin

    2014-01-01

    The dust properties in the Large and Small Magellanic Clouds are studied using the HERITAGE Herschel Key Project photometric data in five bands from 100 to 500 micron. Three simple models of dust emission were fit to the observations: a single temperature blackbody modified by a power- law emissivity (SMBB), a single temperature blackbody modified by a broken power-law emissivity (BEMBB), and two blackbodies with different temperatures, both modified by the same power-law emissivity (TTMBB). Using these models we investigate the origin of the submm excess; defined as the submillimeter (submm) emission above that expected from SMBB models fit to observations < 200 micron. We find that the BEMBB model produces the lowest fit residuals with pixel-averaged 500 micron submm excesses of 27% and 43% for the LMC and SMC, respectively. Adopting gas masses from previous works, the gas-to-dust ratios calculated from our the fitting results shows that the TTMBB fits require significantly more dust than are available e...

  15. Aeroelastic modelling without the need for excessive computing power

    Energy Technology Data Exchange (ETDEWEB)

    Infield, D. [Loughborough Univ., Centre for Renewable Energy Systems Technology, Dept. of Electronic and Electrical Engineering, Loughborough (United Kingdom)

    1996-09-01

    The aeroelastic model presented here was developed specifically to represent a wind turbine manufactured by Northern Power Systems which features a passive pitch control mechanism. It was considered that this particular turbine, which also has low solidity flexible blades, and is free yawing, would provide a stringent test of modelling approaches. It was believed that blade element aerodynamic modelling would not be adequate to properly describe the combination of yawed flow, dynamic inflow and unsteady aerodynamics; consequently a wake modelling approach was adopted. In order to keep computation time limited, a highly simplified, semi-free wake approach (developed in previous work) was used. a similarly simple structural model was adopted with up to only six degrees of freedom in total. In order to take account of blade (flapwise) flexibility a simple finite element sub-model is used. Good quality data from the turbine has recently been collected and it is hoped to undertake model validation in the near future. (au)

  16. Modelling gas markets - a survey

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This report reviews research of relevance to the analysis of present and future developments of the European natural gas market. The research activities considered are confined to (1) numerical models for gas markets, (2) analyses of energy demand, and (3) analyses of behaviour and cost structures in the transmission and distribution sector. Most of the market models are strictly micro economic and assume perfect competition or a game-theoretical equilibrium. They use sophisticated solution concepts, but very simplified specifications of supply and demand functions. Most of the research on demand is econometric analyses. These have more detailed model specification than have the aggregated market models. It is found, however, that the econometric literature based on neo-classical economics has not yielded unambiguous results and the specifications disregard important real world aspects of gas demand. The section on demand concludes that the extent of the gas grid is an important determinant for gas demand, but there has been virtually no research on what determines this variable. Data about transmission and distribution of gas in Europe is scarce and only a few non-econometric and virtually no econometric analyses are available. However, some conclusions can be made from relevant North American literature: (1) there has been significant autonomous technical progress in the transmission industry, (2) distribution costs strongly depend on geographical and other conditions, and (3) ownership, whether private or public, may be important for distribution costs and pricing policies. 56 refs., 3 figs., 1 tab.

  17. Gas-Filled Capillary Model

    Science.gov (United States)

    Steinhauer, L. C.; Kimura, W. D.

    2006-11-01

    We have developed a 1-D, quasi-steady-state numerical model for a gas-filled capillary discharge that is designed to aid in selecting the optimum capillary radius in order to guide a laser beam with the required intensity through the capillary. The model also includes the option for an external solenoid B-field around the capillary, which increases the depth of the parabolic density channel in the capillary, thereby allowing for propagation of smaller laser beam waists. The model has been used to select the parameters for gas-filled capillaries to be utilized during the Staged Electron Laser Acceleration — Laser Wakefield (STELLA-LW) experiment.

  18. Can we determine what controls the spatio-temporal distribution of d-excess and 17O-excess in precipitation using the LMDZ general circulation model?

    Directory of Open Access Journals (Sweden)

    C. Risi

    2013-09-01

    Full Text Available Combined measurements of the H218O and HDO isotopic ratios in precipitation, leading to second-order parameter D-excess, have provided additional constraints on past climates compared to the H218O isotopic ratio alone. More recently, measurements of H217O have led to another second-order parameter: 17O-excess. Recent studies suggest that 17O-excess in polar ice may provide information on evaporative conditions at the moisture source. However, the processes controlling the spatio-temporal distribution of 17O-excess are still far from being fully understood. We use the isotopic general circulation model (GCM LMDZ to better understand what controls d-excess and 17O-excess in precipitation at present-day (PD and during the last glacial maximum (LGM. The simulation of D-excess and 17O-excess is evaluated against measurements in meteoric water, water vapor and polar ice cores. A set of sensitivity tests and diagnostics are used to quantify the relative effects of evaporative conditions (sea surface temperature and relative humidity, Rayleigh distillation, mixing between vapors from different origins, precipitation re-evaporation and supersaturation during condensation at low temperature. In LMDZ, simulations suggest that in the tropics convective processes and rain re-evaporation are important controls on precipitation D-excess and 17O-excess. In higher latitudes, the effect of distillation, mixing between vapors from different origins and supersaturation are the most important controls. For example, the lower d-excess and 17O-excess at LGM simulated at LGM are mainly due to the supersaturation effect. The effect of supersaturation is however very sensitive to a parameter whose tuning would require more measurements and laboratory experiments. Evaporative conditions had previously been suggested to be key controlling factors of d-excess and 17O-excess, but LMDZ underestimates their role. More generally, some shortcomings in the simulation of 17O-excess

  19. K-Ar age of young volcanic rocks and excess argon--Binary mixing model and quantitative study of excess argon effect

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A binary mixing model for excess argon is suggested in the note. According to this model and the data of excess argon component obtained in our experiment , a quantitative study of the effect of excess argon on real K-Ar age of young volcanic rocks is done. The result indicates that the effect of 5% excess argon component in samples on K-Ar age of the samples more than 2 Ma is less than 7.36% and can lead K-Ar age of 0.5 Ma samples to increase by 32.4%, while 1% excess argon component leads K-Ar age of 0.5 Ma samples to increase by 6.26%. Therefore, when pre-processed excess argon component is ≤1%, K-Ar age of the samples more than 0.5 Ma should be credible. On this basis we suggest a principal opinion for evaluation of previous K-Ar dating results and propose that the matrix is used to determine K-Ar age of young volcanic rocks. For the samples less than 0.2 Ma, in the case of high excess argon content, even if only 1% excess argon component exists in their matrix, it can also greatly affect their K-A age. Thus it must be careful to treat the dating result.

  20. Denitrification rates and excess nitrogen gas concentrations in the Arabian Sea oxygen deficient zone

    Digital Repository Service at National Institute of Oceanography (India)

    Devol, A.H.; Uhlenhopp, A.G.; Naqvi, S.W.A.; Brandes, J.A.; Jayakumar, D.A.; Naik, H.; Gaurin, S.; Codispoti, L.A.; Yoshinari, T.

    Rates of canonical, i.e. heterotrophic, water-column denitrification were measured by sup(15)N incubation techniques at a number of coastal and open ocean stations in the Arabian Sea. Measurements of N2 :Ar gas ratios were also made to obtain...

  1. Enantiomeric Excess Determination for Monosaccharides Using Chiral Transmission to Cold Gas-Phase Tryptophan in Ultraviolet Photodissociation

    Science.gov (United States)

    Fujihara, Akimasa; Maeda, Naoto; Doan, Thuc N.; Hayakawa, Shigeo

    2017-02-01

    Chiral transmission between monosaccharides and amino acids via photodissociation in the gas phase was examined using a tandem mass spectrometer fitted with an electrospray ionization source and a cold ion trap in order to investigate the origin of the homochirality of biomolecules in molecular clouds. Ultraviolet photodissociation mass spectra of cold gas-phase noncovalent complexes of the monosaccharide enantiomers glucose (Glc) and galactose (Gal) with protonated l-tryptophan H+( l-Trp) were obtained by photoexcitation of the indole ring of l-Trp. l-Trp dissociated via Cα-Cβ bond cleavage when noncovalently complexed with d-Glc; however, no dissociation of l-Trp occurred in the homochiral H+( l-Trp)( l-Glc) noncovalent complex, where the energy absorbed by l-Trp was released through the evaporation of l-Glc. This enantioselective photodissociation of Trp was due to the transmission of chirality from Glc to Trp via photodissociation in the gas-phase noncovalent complexes, and was applied to the quantitative chiral analysis of monosaccharides. The enantiomeric excess of monosaccharides in solution could be determined by measuring the relative abundance of the two product ions in a single photodissociation mass spectrum of the cold gas-phase noncovalent complex with H+( l-Trp), and by referring to the linear relationships derived in this work.

  2. Perumusan Model Moneter Berdasarkan Perilaku Gas Ideal

    Directory of Open Access Journals (Sweden)

    Rachmad Resmiyanto

    2014-04-01

    Full Text Available Telah disusun sebuah model moneter yang berdasarkan perilaku gas ideal. Model disusun dengan menggunakan metode kias/analogi. Model moneter gas ideal mengiaskan jumlah uang beredar dengan volume gas, daya beli dengan tekanan gas dan produksi barang dengan suhu gas. Model ini memiliki formulasi yang berbeda dengan Teori Kuantitas Uang (Quantity Theory of Money yang dicetuskan oleh Irving Fisher, model moneter Marshal-Pigou dari Cambridge serta model moneter ala Keynes. Selama ini 3 model tersebut dianggap sebagai model yang mapan dalam teori moneter pada buku-buku teks ekonomi. Model moneter gas ideal dapat menjadi cara pandang baru terhadap sistem moneter.

  3. Star formation in galaxy mergers: ISM turbulence, dense gas excess, and scaling relations for disks and starbusts

    CERN Document Server

    Bournaud, Frederic; Chapon, Damien; Teyssier, Romain

    2010-01-01

    Galaxy interactions and mergers play a significant, but still debated and poorly understood role in the star formation history of galaxies. Numerical and theoretical models cannot yet explain the main properties of merger-induced starbursts, including their intensity and their spatial extent. Usually, the mechanism invoked in merger-induced starbursts is a global inflow of gas towards the central kpc, resulting in a nuclear starburst. We show here, using high-resolution AMR simulations and comparing to observations of the gas component in mergers, that the triggering of starbursts also results from increased ISM turbulence and velocity dispersions in interacting systems. This forms cold gas that are denser and more massive than in quiescent disk galaxies. The fraction of dense cold gas largely increases, modifying the global density distribution of these systems, and efficient star formation results. Because the starbursting activity is not just from a global compacting of the gas to higher average surface de...

  4. Observation of an Excess in the Search for the Standard Model Higgs Boson at ALEPH

    CERN Document Server

    Barate, R; Ghez, P; Goy, C; Jézéquel, S; Lees, J P; Martin, F; Merle, E; Minard, M N; Pietrzyk, B; Bravo, S; Casado, M P; Chmeissani, M; Crespo, J M; Fernández, E; Fernández-Bosman, M; Garrido, L; Graugès-Pous, E; López, J; Martínez, M; Merino, G; Miquel, R; Mir, L M; Pacheco, A; Paneque, D; Ruiz, H; Colaleo, A; Creanza, D; De Filippis, N; De Palma, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Azzurri, P; Barklow, Timothy L; Boix, G; Buchmüller, O L; Cattaneo, M; Cerutti, F; Clerbaux, B; Dissertori, G; Drevermann, H; Forty, Roger W; Frank, M; Gianotti, F; Greening, T C; Hansen, J B; Harvey, J; Hutchcroft, D E; Janot, P; Jost, B; Kado, M; Lemaître, V; Maley, P; Mato, P; Minten, Adolf G; Moutoussi, A; Ranjard, F; Rolandi, Luigi; Schlatter, W D; Schmitt, M; Schneider, O; Spagnolo, P; Tejessy, W; Teubert, F; Tournefier, E; Valassi, Andrea; Ward, J J; Wright, A E; Ajaltouni, Ziad J; Badaud, F; Dessagne, S; Falvard, A; Fayolle, D; Gay, P; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Pascolo, J M; Perret, P; Podlyski, F; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Vayaki, Anna; Blondel, A; Brient, J C; Machefert, F P; Rougé, A; Swynghedauw, M; Tanaka, R; Videau, H L; Focardi, E; Parrini, G; Zachariadou, K; Antonelli, A; Antonelli, M; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Chalmers, M; Halley, A W; Kennedy, J; Lynch, J G; Negus, P; O'Shea, V; Räven, B; Smith, D; Teixeira-Dias, P; Thompson, A S; Cavanaugh, R J; Dhamotharan, S; Geweniger, C; Hanke, P; Hepp, V; Kluge, E E; Leibenguth, G; Putzer, A; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Davies, G; Dornan, Peter J; Girone, M; Marinelli, N; Nowell, J; Przysiezniak, H; Sedgbeer, J K; Thompson, J C; Thomson, E; White, R; Ghete, V M; Girtler, P; Kneringer, E; Kuhn, D; Rudolph, G; Bouhova-Thacker, E; Bowdery, C K; Clarke, D P; Ellis, G; Finch, A J; Foster, F; Hughes, G; Jones, R W L; Pearson, M R; Robertson, N A; Smizanska, M; Giehl, I; Hölldorfer, F; Jakobs, K; Kleinknecht, K; Kröcker, M; Müller, A S; Nürnberger, H A; Quast, G; Renk, B; Rohne, E; Sander, H G; Schmeling, S; Wachsmuth, H W; Zeitnitz, C; Ziegler, T; Bonissent, A; Carr, J; Coyle, P; Curtil, C; Ealet, A; Fouchez, D; Leroy, O; Kachelhoffer, T; Payre, P; Rousseau, D; Tilquin, A; Aleppo, M; Gilardoni, S S; Ragusa, F; David, A; Dietl, H; Ganis, G; Heister, A; Hüttmann, K; Lütjens, G; Mannert, C; Männer, W; Moser, H G; Schael, S; Settles, Ronald; Stenzel, H; Wolf, G; Boucrot, J; Callot, O; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacholkowska, A; Serin, L; Veillet, J J; Videau, I; De Vivie de Régie, J B; Yuan, C; Zerwas, D; Bagliesi, G; Boccali, T; Calderini, G; Ciulli, V; Foà, L; Giammanco, A; Giassi, A; Ligabue, F; Messineo, A; Palla, Fabrizio; Rizzo, G; Sanguinetti, G; Sciabà, A; Sguazzoni, G; Tenchini, Roberto; Venturi, A; Verdini, P G; Blair, G A; Coles, J; Cowan, G D; Green, M G; Jones, L T; Medcalf, T; Strong, J A; Clifft, R W; Edgecock, T R; Norton, P R; Tomalin, I R; Bloch-Devaux, B; Boumediene, D E; Colas, P; Fabbro, B; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Rosowsky, A; Seager, P; Trabelsi, A; Tuchming, B; Vallage, B; Konstantinidis, N P; Loomis, C; Litke, A M; Taylor, G; Booth, C N; Cartwright, S L; Combley, F; Hodgson, P N; Lehto, M H; Thompson, L F; Affholderbach, K; Böhrer, A; Brandt, S; Grupen, Claus; Hess, J; Misiejuk, A; Prange, G; Sieler, U; Borean, C; Giannini, G; Gobbo, B; He, H; Pütz, J; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Cranmer, K; Elmer, P; Ferguson, D P S; Gao, Y; González, S; Hayes, O J; Hu, H; Jin, S; Kile, J; McNamara, P A; Nielsen, J; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Shao, N; Von Wimmersperg-Töller, J H; Steinberger, J; Walsh, J; Wiedenmann, W; Wu, J; Wu Sau Lan; Wu, X; Zobernig, G

    2000-01-01

    A search has been performed for the Standard Model Higgs boson in the data sample collected with the ALEPH detector at LEP, at centre-of-mass energies up to 209 GeV. An excess of 3 $\\sigma$ beyond the background expectation is found, consistent with the production of the Higgs boson with a mass near 114 GeV=c^2 . Much of this excess is seen in the four-jet analyses, where three high purity events are selected.

  5. Observation of an excess in the search for the Standard Model Higgs boson at ALEPH

    Science.gov (United States)

    ALEPH Collaboration; Barate, R.; De Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Jezequel, S.; Lees, J.-P.; Martin, F.; Merle, E.; Minard, M.-N.; Pietrzyk, B.; Bravo, S.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Graugés, E.; Lopez, J.; Martinez, M.; Merino, G.; Miquel, R.; Mir, Ll. M.; Pacheco, A.; Paneque, D.; Ruiz, H.; Colaleo, A.; Creanza, D.; De Filippis, N.; de Palma, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Azzurri, P.; Barklow, T.; Boix, G.; Buchmüller, O.; Cattaneo, M.; Cerutti, F.; Clerbaux, B.; Dissertori, G.; Drevermann, H.; Forty, R. W.; Frank, M.; Gianotti, F.; Greening, T. C.; Hansen, J. B.; Harvey, J.; Hutchcroft, D. E.; Janot, P.; Jost, B.; Kado, M.; Lemaitre, V.; Maley, P.; Mato, P.; Minten, A.; Moutoussi, A.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Schmitt, M.; Schneider, O.; Spagnolo, P.; Tejessy, W.; Teubert, F.; Tournefier, E.; Valassi, A.; Ward, J. J.; Wright, A. E.; Ajaltouni, Z.; Badaud, F.; Dessagne, S.; Falvard, A.; Fayolle, D.; Gay, P.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Pascolo, J. M.; Perret, P.; Podlyski, F.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Wäänänen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Blondel, A.; Brient, J.-C.; Machefert, F.; Rougé, A.; Swynghedauw, M.; Tanaka, R.; Videau, H.; Focardi, E.; Parrini, G.; Zachariadou, K.; Antonelli, A.; Antonelli, M.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Chiarella, V.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Chalmers, M.; Halley, A. W.; Kennedy, J.; Lynch, J. G.; Negus, P.; O'Shea, V.; Raeven, B.; Smith, D.; Teixeira-Dias, P.; Thompson, A. S.; Cavanaugh, R.; Dhamotharan, S.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Leibenguth, G.; Putzer, A.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Davies, G.; Dornan, P. J.; Girone, M.; Marinelli, N.; Nowell, J.; Przysiezniak, H.; Sedgbeer, J. K.; Thompson, J. C.; Thomson, E.; White, R.; Ghete, V. M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bouhova-Thacker, E.; Bowdery, C. K.; Clarke, D. P.; Ellis, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Pearson, M. R.; Robertson, N. A.; Smizanska, M.; Giehl, I.; Hölldorfer, F.; Jakobs, K.; Kleinknecht, K.; Kröcker, M.; Müller, A.-S.; Nürnberger, H.-A.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; Schmeling, S.; Wachsmuth, H.; Zeitnitz, C.; Ziegler, T.; Bonissent, A.; Carr, J.; Coyle, P.; Curtil, C.; Ealet, A.; Fouchez, D.; Leroy, O.; Kachelhoffer, T.; Payre, P.; Rousseau, D.; Tilquin, A.; Aleppo, M.; Gilardoni, S.; Ragusa, F.; David, A.; Dietl, H.; Ganis, G.; Heister, A.; Hüttmann, K.; Lütjens, G.; Mannert, C.; Männer, W.; Moser, H.-G.; Schael, S.; Settles, R.; Stenzel, H.; Wolf, G.; Boucrot, J.; Callot, O.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacholkowska, A.; Serin, L.; Veillet, J.-J.; Videau, I.; de Vivie de Régie, J.-B.; Yuan, C.; Zerwas, D.; Bagliesi, G.; Boccali, T.; Calderini, G.; Ciulli, V.; Foà, L.; Giammanco, A.; Giassi, A.; Ligabue, F.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Sguazzoni, G.; Steinberger, J.; Tenchini, R.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Coles, J.; Cowan, G.; Green, M. G.; Jones, L. T.; Medcalf, T.; Strong, J. A.; Clifft, R. W.; Edgecock, T. R.; Norton, P. R.; Tomalin, I. R.; Bloch-Devaux, B.; Boumediene, D.; Colas, P.; Fabbro, B.; Lançon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Seager, P.; Trabelsi, A.; Tuchming, B.; Vallage, B.; Konstantinidis, N.; Loomis, C.; Litke, A. M.; Taylor, G.; Booth, C. N.; Cartwright, S.; Combley, F.; Hodgson, P. N.; Lehto, M.; Thompson, L. F.; Affholderbach, K.; Böhrer, A.; Brandt, S.; Grupen, C.; Hess, J.; Misiejuk, A.; Prange, G.; Sieler, U.; Borean, C.; Giannini, G.; Gobbo, B.; He, H.; Putz, J.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Cranmer, K.; Elmer, P.; Ferguson, D. P. S.; Gao, Y.; González, S.; Hayes, O. J.; Hu, H.; Jin, S.; Kile, J.; McNamara, P. A.; Nielsen, J.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Shao, N.; von Wimmersperg-Toeller, J. H.; Walsh, J.; Wiedenmann, W.; Wu, J.; Wu, S. L.; Wu, X.; Zobernig, G.

    2000-12-01

    A search has been performed for the Standard Model Higgs boson in the data sample collected with the ALEPH detector at LEP, at centre-of-mass energies up to 209GeV. An excess of /3σ beyond the background expectation is found, consistent with the production of the Higgs boson with a mass near 114GeV/c2. Much of this excess is seen in the four-jet analyses, where three high purity events are selected.

  6. Solubility of solids in supercritical fluids using equations of state — excess Gibbs free energy models

    OpenAIRE

    Verotti Filho, C.; Costa, Glória Meyberg Nunes

    1996-01-01

    p. 351–355 Solubilities of several organic solids in four supercritical fluids are calculated with Soave and Peng-Robinson equations of state, incorporating excess Gibbs free energy into the mixing rules, with Heidemann-Kokal, Wong-Sandler and MHV2 procedures. Three excess Gibbs free energy models are used in the mixing rules: NRTL, UNiQUAC and UNIFAC. Furthermore, a comparison between these mixing rules and conventional two-binary-parameter form and modification of the excluded volume par...

  7. 750 GeV diphoton excess confronted with a top-pion in the TTM model

    CERN Document Server

    Guo, Yu-Chen; Zhao, Zhen-hua

    2016-01-01

    The latest LHC data suggest an intriguing excess at $m_{\\gamma\\gamma} = 750$ GeV which apparently requires an explanation from the beyond standard model physics. In this note we explore the possibility for this signal to arise from a top-pion in the Top Triangle Moose model which can be viewed as a dimensional-deconstruction version of the top-color assisted technicolor model. We demonstrate that the observed excess can be accommodated by and has important implications for this interesting model.

  8. 750 GeV diphoton excess confronted with a top-pion in the TTM model

    Science.gov (United States)

    Guo, Yu-Chen; Yue, Chong-Xing; Zhao, Zhen-Hua

    2016-05-01

    The latest LHC data suggest an intriguing excess at mγγ = 750GeV which apparently requires an explanation from the beyond standard model physics. In this paper, we explore the possibility for this signal to arise from a top-pion in the Top Triangle Moose model which can be viewed as a dimensional-deconstruction version of the top-color assisted technicolor model. We demonstrate that the observed excess can be accommodated by and has important implications for this interesting model.

  9. Examination of a sociocultural model of excessive exercise among male and female adolescents.

    Science.gov (United States)

    White, James; Halliwell, Emma

    2010-06-01

    There is substantial evidence that sociocultural pressures and body image disturbances can lead to disordered eating, yet few studies have examined their impact on excessive exercise. The study adapted a sociocultural model for disordered eating to predict excessive exercise using data from boys and girls in early adolescence (N=421). Perceived sociocultural pressures to lose weight and build muscle, body image disturbance and appearance investment were associated with a compulsive need to exercise. Adolescents' investment in appearance and body image disturbance fully mediated the relationship between sociocultural pressures and a compulsive need for exercise. There was no support for the meditational model in predicting adolescents' frequency or duration of exercise. Results support the sociocultural model as an explanatory model for excessive exercise, but suggest appearance investment and body image disturbance are important mediators of sociocultural pressures. 2010 Elsevier Ltd. All rights reserved.

  10. Supersoft SUSY models and the 750 GeV diphoton excess, beyond effective operators

    Science.gov (United States)

    Carpenter, Linda M.; Colburn, Russell; Goodman, Jessica

    2016-07-01

    We propose that the sbino, the scalar partner of a Dirac bino, can explain the 750 GeV diphoton excess observed by the ATLAS and CMS Collaborations. We first argue for the existence of couplings between sbino to pairs of Standard Model gauge bosons using effective operator analysis. We then analyze the minimal completion of the effective operator model in which the sbino couples to pairs of gauge bosons through loops of heavy sfermions, with the sfermion-bino coupling originating from scalar potential D-terms. We find that the sbino model may be fit the 750 GeV excess by considering gluon fusion processes with decay to diphotons.

  11. Supersoft SUSY Models and the 750 GeV Diphoton Excess, Beyond Effective Operators

    CERN Document Server

    Carpenter, Linda M; Goodman, Jessica

    2015-01-01

    We propose that the sbino, the scalar partner of a Dirac bino can explain the 750 GeV diphoton excess observed by ATLAS and LHC . We analyze a model in which the sbino couples to pairs of Standard Model (SM) gauge bosons. We analyze an effective operator model, as well as a completion in which the sbino couples to pairs of gauge bosons through loops of heavy sfermions. We find that the sbino may be given an appreciable decay width through tree level coupling in the Higgs sector. We find that we may fit the 750 GeV excess by considering gluon fusion processes with decay to diphotons.

  12. Percolation model of excess electrical noise in transition-edge sensors

    Energy Technology Data Exchange (ETDEWEB)

    Lindeman, M.A. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)]. E-mail: lindeman@wisp.physics.wisc.edu; Anderson, M.B. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Bandler, S.R. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bilgri, N. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Chervenak, J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gwynne Crowder, S. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Fallows, S. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Figueroa-Feliciano, E. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Finkbeiner, F. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Iyomoto, N. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kelley, R. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kilbourne, C.A. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Lai, T. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Man, J. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); McCammon, D. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Nelms, K.L. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Porter, F.S. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Rocks, L.E. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Saab, T. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Sadleir, J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Vidugiris, G. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)

    2006-04-15

    We present a geometrical model to describe excess electrical noise in transition-edge sensors (TESs). In this model, a network of fluctuating resistors represents the complex dynamics inside a TES. The fluctuations can cause several resistors in series to become superconducting. Such events short out part of the TES and generate noise because much of the current percolates through low resistance paths. The model predicts that excess white noise increases with decreasing TES bias resistance (R/R{sub N}) and that perpendicular zebra stripes reduce noise and alpha of the TES by reducing percolation.

  13. Improved Cosmic-Ray Injection Models and the Galactic Center Gamma-Ray Excess

    CERN Document Server

    Carlson, Eric; Profumo, Stefano

    2016-01-01

    Fermi-LAT observations of the Galactic Center (GC) have revealed a spherically- symmetric excess of GeV gamma rays extending to at least 10 deg from the dynamical center of the Galaxy. A critical uncertainty in extracting the intensity, spectrum, and morphology of this excess concerns the accuracy of astrophysical diffuse gamma-ray emission models near the GC. Recently, it has been noted that many diffuse emission models utilize a cosmic-ray injection rate far below that predicted based on the observed star formation rate in the Central Molecular Zone. In this study, we add a cosmic-ray injection component which non-linearly traces the Galactic H2 density determined in three-dimensions, and find that the associated gamma-ray emission is degenerate with many properties of the GC gamma-ray excess. In models that utilize a large sideband (40x40 deg surrounding the GC) to normalize the best-fitting diffuse emission models, the intensity of the GC excess decreases by a factor of 2, and the morphology of the excess...

  14. The 750 GeV LHC diphoton excess from a baryon number conserving string model

    CERN Document Server

    Kokorelis, Christos

    2016-01-01

    We propose an explanation of the LHC data excess resonance of 750 GeV in the diphoton distribution using D-brane models, with gauged baryon number, which accommodate the Standard Model together with vector like exotics. We identify the 750 GeV scalar as either the sneutrino (${\\tilde \

  15. Excess covariance and dynamic instability in a multi-asset model

    NARCIS (Netherlands)

    Anufriev, M.; Bottazzi, G.; Marsili, M.; Pin, P.

    2011-01-01

    The presence of excess covariance in financial price returns is an accepted empirical fact: the price dynamics of financial assets tend to be more correlated than their fundamentals would justify. We propose an intertemporal equilibrium multi-assets model of financial markets with an explicit and

  16. A SUSY inspired simplified model for the 750 GeV diphoton excess

    Energy Technology Data Exchange (ETDEWEB)

    Gabrielli, E. [Dipart. di Fisica Teorica, Università di Trieste, Strada Costiera 11, I-34151 Trieste (Italy); INFN, Sezione di Trieste, Via Valerio 2, I-34127 Trieste (Italy); NICPB, Rävala 10, Tallinn 10143 (Estonia); Kannike, K., E-mail: kannike@cern.ch [NICPB, Rävala 10, Tallinn 10143 (Estonia); Mele, B. [INFN, Sezione di Roma, c/o Dipart. di Fisica, Università di Roma “La Sapienza”, Piazzale Aldo Moro 2, I-00185 Rome (Italy); Raidal, M. [NICPB, Rävala 10, Tallinn 10143 (Estonia); Institute of Physics, University of Tartu (Estonia); Spethmann, C.; Veermäe, H. [NICPB, Rävala 10, Tallinn 10143 (Estonia)

    2016-05-10

    The evidence for a new neutral scalar particle from the 750 GeV diphoton excess, and the absence of any other signal of new physics at the LHC so far, suggests the existence of new coloured scalars. To study this possibility, we propose a supersymmetry inspired simplified model, extending the Standard Model with a singlet scalar and with heavy scalar fields carrying both colour and electric charges – new scalar quarks. To allow the latter to decay, and to generate the dark matter of the Universe, we also add a neutral fermion to the particle content. We show that this model provides a two-parameter fit to the observed diphoton excess consistently with cosmology, while the allowed parameter space is bounded by the consistency of the model. In the context of our simplified model this implies the existence of other supersymmetric particles accessible at the LHC, rendering this scenario falsifiable.

  17. A Comparison of the Nitrogen Gas Excess Versus the Fixed Nitrogen Deficit in Two Major Oxygen Deficient Zones of the World

    Science.gov (United States)

    Devol, A. H.; Chang, B. X.

    2006-12-01

    This study compares the nitrogen gas excesses in the oxygen deficient zones (ODZs) of the Eastern Tropical South Pacific (ETSP) and the Arabian Sea. These are two of the three largest ODZs in the world. In the near absence of oxygen, heterotrophic denitrification is the dominant form of respiration in these regions which, coupled to the sheer vastness of the ODZs, makes them a globally significant sink of marine fixed nitrogen. Thus, understanding how nitrogen is cycled in the ODZs is important to understanding the global nitrogen cycle. We measured profiles of nitrogen gas and argon concentrations through the ODZs of the ETSP and the Arabian Sea in the fall of 2005 and 2004, respectively. Nitrogen gas concentrations were normalized to argon concentrations to eliminate variations due to physical changes in the water mass. Any nitrogen gas in excess of the background nitrogen gas concentration was interpreted to be from denitrification. In the Arabian Sea ODZ, we found the nitrogen gas excess up to 18 uM N. Using stoichiometric relationships of nitrate and phosphate specific to the Arabian Sea, previous workers have estimated the nitrate deficit in the Arabian Sea ODZ to be no more than 12 uM N, which is only two-thirds of the nitrogen gas excess. In the ODZ of the ETSP, we found the nitrogen gas excess to be 15 uM N and the estimated nitrate deficit to be comparable, which suggests that in the ETSP, the nitrogen gas excess may be accounted for by the nitrate deficit. In the Arabian Sea ODZ, however, there is 50% more nitrogen in the excess than can be accounted for by the nitrate deficit. Several explanations are possible for this discrepancy, but probably the most significant is the likely greater contribution of nitrogen fixation to the overall productivity of the Arabian Sea compared to the ETSP. Nitrogen fixing bacteria are known to have an elevated N:P relative to the assumed near-Redfieldian organic matter falling into the ODZ. Nitrogen fixation has been

  18. Color excesses of type Ia supernovae from the single-degenerate channel model

    Institute of Scientific and Technical Information of China (English)

    Xiang-Cun Meng; Xue-Fei Chen; Zhan-Wen Han; Wu-Ming Yang

    2009-01-01

    The single degenerate model is the most widely accepted progenitor model of type Ia supernovae (SNe Ia),in which a carbon-oxygen white dwarf (CO WD) accretes hydrogen-rich material from a main sequence or a slightly evolved star (WD+MS) to increase its mass,and explodes when its mass approaches the Chandrasekhar mass limit.During the mass transfer phase between the two components,an optically thick wind may occur and the material lost as wind may exist as circumstellar material (CSM).Searching for the CSM around a progenitor star is helpful for discriminating different progenitor models of SNe Ia.In addition,the CSM is a source of color excess.The purpose of this paper is to study the color excess produced from the single-degenerate progenitor model with an optically thick wind,and reproduce the distribution of color excesses of SNe Ia.Meng et al.systemically carried out binary evolution calculations of the WD +MS systems for various metallicities and showed the parameters of the systems before Roche lobe overflow and at the moment of supernova explosion in Meng & Yang.With the results of Meng et al.,we calculate the color excesses of SNe Ia at maximum light via a simple analytic method.We reproduce the distribution of color excesses of SNe Ia by our binary population synthesis approach if the velocity of the optically thick wind is taken to be an order of magnitude of 10kin s~(-1).However,if the wind velocity is larger than 100km s~(-1),the reproduction is bad.

  19. Adopting epidemic model to optimize medication and surgical intervention of excess weight

    Science.gov (United States)

    Sun, Ruoyan

    2017-01-01

    We combined an epidemic model with an objective function to minimize the weighted sum of people with excess weight and the cost of a medication and surgical intervention in the population. The epidemic model is consisted of ordinary differential equations to describe three subpopulation groups based on weight. We introduced an intervention using medication and surgery to deal with excess weight. An objective function is constructed taking into consideration the cost of the intervention as well as the weight distribution of the population. Using empirical data, we show that fixed participation rate reduces the size of obese population but increases the size for overweight. An optimal participation rate exists and decreases with respect to time. Both theoretical analysis and empirical example confirm the existence of an optimal participation rate, u*. Under u*, the weighted sum of overweight (S) and obese (O) population as well as the cost of the program is minimized. This article highlights the existence of an optimal participation rate that minimizes the number of people with excess weight and the cost of the intervention. The time-varying optimal participation rate could contribute to designing future public health interventions of excess weight.

  20. Modeling the Excess Cell Surface Stored in a Complex Morphology of Bleb-Like Protrusions

    Science.gov (United States)

    Wessler, Timothy; Yang, Xiaofeng; Chen, Alex; Roach, Nathan; Elston, Timothy C.; Wang, Qi; Jacobson, Ken; Forest, M. Gregory

    2016-01-01

    Cells transition from spread to rounded morphologies in diverse physiological contexts including mitosis and mesenchymal-to-amoeboid transitions. When these drastic shape changes occur rapidly, cell volume and surface area are approximately conserved. Consequently, the rounded cells are suddenly presented with a several-fold excess of cell surface whose area far exceeds that of a smooth sphere enclosing the cell volume. This excess is stored in a population of bleb-like protrusions (BLiPs), whose size distribution is shown by electron micrographs to be skewed. We introduce three complementary models of rounded cell morphologies with a prescribed excess surface area. A 2D Hamiltonian model provides a mechanistic description of how discrete attachment points between the cell surface and cortex together with surface bending energy can generate a morphology that satisfies a prescribed excess area and BLiP number density. A 3D random seed-and-growth model simulates efficient packing of BLiPs over a primary rounded shape, demonstrating a pathway for skewed BLiP size distributions that recapitulate 3D morphologies. Finally, a phase field model (2D and 3D) posits energy-based constitutive laws for the cell membrane, nematic F-actin cortex, interior cytosol, and external aqueous medium. The cell surface is equipped with a spontaneous curvature function, a proxy for the cell surface-cortex couple, that is a priori unknown, which the model “learns” from the thin section transmission electron micrograph image (2D) or the “seed and growth” model image (3D). Converged phase field simulations predict self-consistent amplitudes and spatial localization of pressure and stress throughout the cell for any posited stationary morphology target and cell compartment constitutive properties. The models form a general framework for future studies of cell morphological dynamics in a variety of biological contexts. PMID:27015526

  1. Modeling the Excess Cell Surface Stored in a Complex Morphology of Bleb-Like Protrusions.

    Directory of Open Access Journals (Sweden)

    Maryna Kapustina

    2016-03-01

    Full Text Available Cells transition from spread to rounded morphologies in diverse physiological contexts including mitosis and mesenchymal-to-amoeboid transitions. When these drastic shape changes occur rapidly, cell volume and surface area are approximately conserved. Consequently, the rounded cells are suddenly presented with a several-fold excess of cell surface whose area far exceeds that of a smooth sphere enclosing the cell volume. This excess is stored in a population of bleb-like protrusions (BLiPs, whose size distribution is shown by electron micrographs to be skewed. We introduce three complementary models of rounded cell morphologies with a prescribed excess surface area. A 2D Hamiltonian model provides a mechanistic description of how discrete attachment points between the cell surface and cortex together with surface bending energy can generate a morphology that satisfies a prescribed excess area and BLiP number density. A 3D random seed-and-growth model simulates efficient packing of BLiPs over a primary rounded shape, demonstrating a pathway for skewed BLiP size distributions that recapitulate 3D morphologies. Finally, a phase field model (2D and 3D posits energy-based constitutive laws for the cell membrane, nematic F-actin cortex, interior cytosol, and external aqueous medium. The cell surface is equipped with a spontaneous curvature function, a proxy for the cell surface-cortex couple, that is a priori unknown, which the model "learns" from the thin section transmission electron micrograph image (2D or the "seed and growth" model image (3D. Converged phase field simulations predict self-consistent amplitudes and spatial localization of pressure and stress throughout the cell for any posited stationary morphology target and cell compartment constitutive properties. The models form a general framework for future studies of cell morphological dynamics in a variety of biological contexts.

  2. Colon Hypersensitivity to Distension, Rather Than Excessive Gas Production, Produces Carbohydrate-Related Symptoms in Individuals With Irritable Bowel Syndrome.

    Science.gov (United States)

    Major, Giles; Pritchard, Sue; Murray, Kathryn; Alappadan, Jan Paul; Hoad, Caroline L; Marciani, Luca; Gowland, Penny; Spiller, Robin

    2017-01-01

    reached the symptom threshold after inulin intake, peak symptom intensity correlated with peak colonic gas (r = 0.57; P colonic hypersensitivity to distension, rather than excessive gas production, produces carbohydrate-related symptoms in patients with IBS. Clinicaltrials.gov no: NCT01776853. Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.

  3. Local influence diagnostics for hierarchical count data models with overdispersion and excess zeros.

    Science.gov (United States)

    Rakhmawati, Trias Wahyuni; Molenberghs, Geert; Verbeke, Geert; Faes, Christel

    2016-11-01

    We consider models for hierarchical count data, subject to overdispersion and/or excess zeros. Molenberghs et al. () and Molenberghs et al. () extend the Poisson-normal generalized linear-mixed model by including gamma random effects to accommodate overdispersion. Excess zeros are handled using either a zero-inflation or a hurdle component. These models were studied by Kassahun et al. (). While flexible, they are quite elaborate in parametric specification and therefore model assessment is imperative. We derive local influence measures to detect and examine influential subjects, that is subjects who have undue influence on either the fit of the model as a whole, or on specific important sub-vectors of the parameter vector. The latter include the fixed effects for the Poisson and for the excess-zeros components, the variance components for the normal random effects, and the parameters describing gamma random effects, included to accommodate overdispersion. Interpretable influence components are derived. The method is applied to data from a longitudinal clinical trial involving patients with epileptic seizures. Even though the data were extensively analyzed in earlier work, the insight gained from the proposed diagnostics, statistically and clinically, is considerable. Possibly, a small but important subgroup of patients has been identified. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. A Lattice-Gas Model of Microemulsions

    CERN Document Server

    Boghosian, B M; Emerton, A N; Boghosian, Bruce M.; Coveney, Peter V.; Emerton, Andrew N.

    1995-01-01

    We develop a lattice gas model for the nonequilibrium dynamics of microemulsions. Our model is based on the immiscible lattice gas of Rothman and Keller, which we reformulate using a microscopic, particulate description so as to permit generalisation to more complicated interactions, and on the prescription of Chan and Liang for introducing such interparticle interactions into lattice gas dynamics. We present the results of simulations to demonstrate that our model exhibits the correct phenomenology, and we contrast it with both equilibrium lattice models of microemulsions, and to other lattice gas models.

  5. Models of 750 GeV quarkonium and the LHC excesses

    CERN Document Server

    Hamaguchi, Koichi

    2016-01-01

    We investigate models involving a vector-like quark X, which forms a 750 GeV bound state and reproduces the observed diphoton signals at the LHC, in connection with other excesses in the LHC data. An exotic hypercharge of -4/3 is required to fit the signal cross section, which indicates that there is additional particle(s) that mediates the decay of X in the full theory. We find that, introducing an SU(2) doublet vector-like quark of mass around 600 GeV in our UV-complete framework can accommodate not only the diphoton but also the on-Z excess (and potentially a slight excess in the monojet events). Our models also include a dark matter candidate. The most useful way to probe the models at the LHC is via monojet searches. The relic dark matter density is largely determined by coannihilation effects, and indirect detection of dark matter annihilation signals is the alternative and complementary probe of our models.

  6. Lovastatin Corrects Excess Protein Synthesis and Prevents Epileptogenesis in a Mouse Model of Fragile X Syndrome

    OpenAIRE

    Chuang, Shih-Chieh; Chubykin, Alexander A.; Sidorov, Michael; Bianchi, Riccardo; Wong, Robert K.S.; Osterweil, Emily; Bear, Mark; Chubykin, Alexander A.

    2013-01-01

    Many neuropsychiatric symptoms of fragile X syndrome (FXS) are believed to be a consequence of altered regulation of protein synthesis at synapses. We discovered that lovastatin, a drug that is widely prescribed for the treatment of high cholesterol, can correct excess hippocampal protein synthesis in the mouse model of FXS and can prevent one of the robust functional consequences of increased protein synthesis in FXS, epileptogenesis. These data suggest that lovastatin is potentially disease...

  7. Lovastatin corrects excess protein synthesis and prevents epileptogenesis in a mouse model of fragile X syndrome

    OpenAIRE

    Osterweil, Emily K.; Chuang, Shih-Chieh; Chubykin, Alexander A.; Sidorov, Michael; Bianchi, Riccardo; Wong, Robert K. S.; Bear, Mark F.

    2013-01-01

    Many neuropsychiatric symptoms of fragile X syndrome (FXS) are believed to be a consequence of altered regulation of protein synthesis at synapses. We discovered that lovastatin, a drug that is widely prescribed for treatment of high cholesterol, can correct excess hippocampal protein synthesis in themouse model of FXS and can prevent one of the robust functional consequences of increased protein synthesis in FXS, epileptogenesis. These data suggest that lovastatin is potentially disease modi...

  8. The Galactic Center Region Gamma Ray Excess from A Supersymmetric Leptophilic Higgs Model

    CERN Document Server

    Marshall, Gardner

    2011-01-01

    In a recent paper by Hooper and Goodenough, data from the Fermi Gamma Ray Telescope was analyzed and an excess of gamma rays was found in the emission spectrum from the Galactic Center Region. Hooper and Goodenough show that the excess can be well explained by 7-10 GeV annihilating dark matter with a power law density profile if the dark matter annihilates predominantly to tau pairs. In this paper we present such a dark matter model by extending the MSSM to include four Higgs doublets and one scalar singlet. A Z2 symmetry is imposed that enforces a Yukawa structure so that the up quarks, down quarks, and leptons each receive mass from a distinct doublet. This leads to an enhanced coupling of scalars to leptons and allows the model to naturally achieve the required phenomenology in order to explain the gamma ray excess. Our model yields the correct dark matter thermal relic density and avoids collider bounds from measurements of the Z width as well as direct production at LEP.

  9. Low energy gamma ray excess confronting a singlet scalar extended inert doublet dark matter model

    Directory of Open Access Journals (Sweden)

    Amit Dutta Banik

    2015-04-01

    Full Text Available Recent study of gamma rays originating from the region of galactic centre has confirmed an anomalous γ-ray excess within the energy range 1–3 GeV. This can be explained as the consequence of pair annihilation of a 31–40 GeV dark matter into bb¯ with thermal annihilation cross-section σv∼1.4–2.0×10−26 cm3/s. In this work we revisit the Inert Doublet Model (IDM in order to explain this gamma ray excess. Taking the lightest inert particle (LIP as a stable DM candidate we show that a 31–40 GeV dark matter derived from IDM will fail to satisfy experimental limits on dark matter direct detection cross-section obtained from ongoing direct detection experiments and is also inconsistent with LHC findings. We show that a singlet extended inert doublet model can easily explain the reported γ-ray excess which is as well in agreement with Higgs search results at LHC and other observed results like DM relic density and direct detection constraints.

  10. The 750 GeV Diphoton excess in a $U(1)$ hidden symmetry model

    CERN Document Server

    Das, Kasinath

    2015-01-01

    Recent results from the experimental collaborations at LHC give hints of a resonance in the diphoton channel at an invariant mass of 750 GeV. We show that such a scalar resonance would be possible in an $U(1)$ extension of the SM where the extended symmetry is hidden and yet to be discovered. We explore the possibilities of accommodating this excess by introducing a minimal extension to the matter content and highlight the parameter space that can accommodate the observed diphoton resonance in the model. The model also predicts new interesting signals that may be observed at the current LHC run.

  11. Excess of positrons in cosmic rays: A Lindbladian model of quantum electrodynamics

    CERN Document Server

    Campos, Andre G; Bondar, Denys I; Rabitz, Herschel

    2015-01-01

    The fraction of positrons and electrons in cosmic rays recently observed on the International Space Station unveiled an unexpected excess of the positrons, undermining the current foundations of cosmic rays sources. We provide a quantum electrodynamics phenomenological model explaining the observed data. This model incorporates electroproduction, in which cosmic ray electrons decelerating in the interstellar medium emit photons that turn into electron-positron pairs. These findings not only advance our knowledge of cosmic ray physics, but also pave the way for computationally efficient formulations of quantum electrodynamics, critically needed in physics and chemistry.

  12. Non-Standard Grain Properties, Dark Gas Reservoir, and Extended Submillimeter Excess, Probed by Herschel in the Large Magellanic Cloud

    CERN Document Server

    Galliano, F; Bernard, J -P; Bot, C; Madden, S C; Roman-Duval, J; Galametz, M; Li, A; Meixner, M; Engelbracht, C W; Lebouteiller, V; Misselt, K; Montiel, E; Panuzzo, P; Reach, W T; Skibba, R

    2011-01-01

    Aims: In this paper, we perform detailed modelling of the Spitzer and Herschel observations of the LMC, in order to: (i) systematically study the uncertainties and biases affecting dust mass estimates; and to (ii) explore the peculiar ISM properties of the LMC. Methods: To achieve these goals, we have modelled the spatially resolved SEDs with two alternate grain compositions, to study the impact of different submillimetre opacities on the dust mass. We have rigorously propagated the observational errors (noise and calibration) through the entire fitting process, in order to derive consistent parameter uncertainties. Results: First, we show that using the integrated SED leads to underestimating the dust mass by ~50 % compared to the value obtained with sufficient spatial resolution, for the region we studied. This might be the case, in general, for unresolved galaxies. Second, we show that Milky Way type grains produce higher gas-to-dust mass ratios than what seems possible according to the element abundances ...

  13. Multiscale modeling of gas-fluidized beds

    NARCIS (Netherlands)

    van der Hoef, Martin Anton; van Sint Annaland, M.; Ye, M.; Andrews, A.T.; Sundaresan, S.; Kuipers, J.A.M.

    2006-01-01

    Numerical models of gas-fluidized beds have become an important tool in the design and scale up of gas-solid chemical reactors. However, a single numerical model which includes the solid-solid and solid-fluid interaction in full detail is not feasible for industrial-scale equipment, and for this

  14. Multiscale modeling of gas-fluidized beds

    NARCIS (Netherlands)

    Hoef, van der M.A.; Sint Annaland, van M.; Andrews, A.T.; Sundaresan, S.; Kuipers, J.A.M.

    2006-01-01

    Numerical models of gas-fluidized beds have become an important tool in the design and scale up of gas-solid chemical reactors. However, a single numerical model which includes the solid-solid and solid-fluid interaction in full detail is not feasible for industrial-scale equipment, and for this rea

  15. Partitioning of excess mortality in population-based cancer patient survival studies using flexible parametric survival models

    Directory of Open Access Journals (Sweden)

    Eloranta Sandra

    2012-06-01

    Full Text Available Abstract Background Relative survival is commonly used for studying survival of cancer patients as it captures both the direct and indirect contribution of a cancer diagnosis on mortality by comparing the observed survival of the patients to the expected survival in a comparable cancer-free population. However, existing methods do not allow estimation of the impact of isolated conditions (e.g., excess cardiovascular mortality on the total excess mortality. For this purpose we extend flexible parametric survival models for relative survival, which use restricted cubic splines for the baseline cumulative excess hazard and for any time-dependent effects. Methods In the extended model we partition the excess mortality associated with a diagnosis of cancer through estimating a separate baseline excess hazard function for the outcomes under investigation. This is done by incorporating mutually exclusive background mortality rates, stratified by the underlying causes of death reported in the Swedish population, and by introducing cause of death as a time-dependent effect in the extended model. This approach thereby enables modeling of temporal trends in e.g., excess cardiovascular mortality and remaining cancer excess mortality simultaneously. Furthermore, we illustrate how the results from the proposed model can be used to derive crude probabilities of death due to the component parts, i.e., probabilities estimated in the presence of competing causes of death. Results The method is illustrated with examples where the total excess mortality experienced by patients diagnosed with breast cancer is partitioned into excess cardiovascular mortality and remaining cancer excess mortality. Conclusions The proposed method can be used to simultaneously study disease patterns and temporal trends for various causes of cancer-consequent deaths. Such information should be of interest for patients and clinicians as one way of improving prognosis after cancer is

  16. Interpreting the 750 GeV diphoton excess within topflavor seesaw model

    Science.gov (United States)

    Cao, Junjie; Shang, Liangliang; Su, Wei; Wang, Fei; Zhang, Yang

    2016-10-01

    We propose that the extension of the Standard Model by typical vector-like SU(2)L doublet fermions and non-singlet scalar field can account for the observed 750 GeV diphoton excess in experimentally allowed parameter space. Such an idea can be realized in a typical topflavor seesaw model where the new resonance X is identified as a CP-even or CP-odd scalar emerging from a certain bi-doublet Higgs field, and it can couple rather strongly to photons and gluons through mediators such as vector-like fermions, scalars as well as gauge bosons predicted by the model. Numerical analysis indicates that the model can predict the central value of the diphoton excess without contradicting any constraints from 8 TeV LHC. Among all the constraints, the tightest one comes from the Zγ channel with σ8 TeVZγ ≲ 3.6 fb, which requires σ13 TeVγγ ≲ 6 fb in most of the favored parameter space. Theoretical issues such as vacuum stability and Landau pole are also addressed.

  17. Galactic gamma ray excess and dark matter phenomenology in a U(1) B- L model

    Science.gov (United States)

    Biswas, Anirban; Choubey, Sandhya; Khan, Sarif

    2016-08-01

    In this work, we have considered a gauged U(1)B-L extension of the Standard Model (SM) with three right handed neutrinos for anomaly cancellation and two additional SM singlet complex scalars with nontrivial B-L charges. One of these is used to spontaneously break the U(1)B-L gauge symmetry, leading to Majorana masses for the neutrinos through the standard Type I seesaw mechanism, while the other becomes the dark matter (DM) candidate in the model. We test the viability of the model to simultaneously explain the DM relic density observed in the CMB data as well as the Galactic Centre (GC) γ-ray excess seen by Fermi-LAT. We show that for DM masses in the range 40-55 GeV and for a wide range of U(1)B-L gauge boson masses, one can satisfy both these constraints if the additional neutral Higgs scalar has a mass around the resonance region. In studying the dark matter phenomenology and GC excess, we have taken into account theoretical as well as experimental constraints coming from vacuum stability condition, Planck bound on DM relic density, LHC and LUX and present allowed areas in the model parameter space consistent with all relevant data, calculate the predicted gamma ray flux from the GC and discuss the related phenomenology.

  18. Interpreting the 750 GeV diphoton excess within topflavor seesaw model

    Directory of Open Access Journals (Sweden)

    Junjie Cao

    2016-10-01

    Full Text Available We propose that the extension of the Standard Model by typical vector-like SU(2L doublet fermions and non-singlet scalar field can account for the observed 750 GeV diphoton excess in experimentally allowed parameter space. Such an idea can be realized in a typical topflavor seesaw model where the new resonance X is identified as a CP-even or CP-odd scalar emerging from a certain bi-doublet Higgs field, and it can couple rather strongly to photons and gluons through mediators such as vector-like fermions, scalars as well as gauge bosons predicted by the model. Numerical analysis indicates that the model can predict the central value of the diphoton excess without contradicting any constraints from 8 TeV LHC. Among all the constraints, the tightest one comes from the Zγ channel with σ8 TeVZγ≲3.6 fb, which requires σ13 TeVγγ≲6 fb in most of the favored parameter space. Theoretical issues such as vacuum stability and Landau pole are also addressed.

  19. A Trio of Metal-Rich Dust and Gas Disks Found Orbiting Candidate White Dwarfs with K-Band Excess

    CERN Document Server

    Farihi, J; Steele, P R; Girven, J; Burleigh, M R; Breedt, E; Koester, D

    2011-01-01

    This paper reports follow-up photometric and spectroscopic observations, including warm Spitzer IRAC photometry of seven white dwarfs from the SDSS with apparent excess flux in UKIDSS K-band observations. Six of the science targets were selected from 16,785 DA star candidates identified either spectroscopically or photometrically within SDSS DR7, spatially cross-correlated with HK detections in UKIDSS DR8. Thus the selection criteria are completely independent of stellar mass, effective temperature above 8000 K, and the presence (or absence) of atmospheric metals. The infrared fluxes of one target are compatible with a spatially-unresolved late M or early L-type companion, while three stars exhibit excess emissions consistent with warm circumstellar dust. These latter targets have spectral energy distributions similar to known dusty white dwarfs with high fractional infrared luminosities (thus the K-band excesses). Optical spectroscopy reveals the stars with disk-like excesses are polluted with heavy elements...

  20. Excess VO2 during ramp exercise is positively correlated to intercostal muscles deoxyhemoglobin levels above the gas exchange threshold in young trained cyclists.

    Science.gov (United States)

    Oueslati, Ferid; Girard, Olivier; Tabka, Zouhair; Ahmaidi, Said

    2016-07-01

    We assessed respiratory muscles oxygenation responses during a ramp exercise to exhaustion and further explored their relationship with the non-linear increase of VO2 (VO2 excess) observed above the gas-exchange threshold. Ten male cyclists completed a ramp exercise to exhaustion on an electromagnetically braked cycle-ergometer with a rate of increment of 30Wmin(-1) with continuous monitoring of expired gases (breath-by-breath) and oxygenation status of intercostal muscles. Maximal inspiratory and expiratory pressure measurements were taken at rest and at exhaustion. The VO2 excess represents the difference between VO2max observed and VO2max expected using linear equation between the VO2 and the intensity before gas-exchange threshold. The deoxyhemoglobin remained unchanged until 60% of maximal aerobic power (MAP) and thereafter increased significantly by 37±18% and 40±22% at 80% and 100% of MAP, respectively. Additionally, the amplitude of deoxyhemoglobin increase between 60 and 100% of MAP positively correlated with the VO2 excess (r=0.69, p<0.05). Compared to exercise start, the oxygen tissue saturation index decreased from 80% of MAP (-4.8±3.2%, p<0.05) onwards. At exhaustion, maximal inspiratory and expiratory pressures declined by 7.8±16% and 12.6±10% (both p<0.05), respectively. In summary, our results suggest a significant contribution of respiratory muscles to the VO2 excess phenomenon.

  1. Thermodynamic modelling of acid gas removal from natural gas using the Extended UNIQUAC model

    DEFF Research Database (Denmark)

    Sadegh, Negar; Stenby, Erling Halfdan; Thomsen, Kaj

    2017-01-01

    Thermodynamics of natural gas sweetening process needs to be known for proper design of natural gas treating plants. Absorption with aqueous N-Methyldiethanolamine is currently the most commonly used process for removal of acid gas (CO2 and H2S) impurities from natural gas. Model parameters...... for the Extended UNIQUAC model have already been determined by the same authors to calculate single acid gas solubility in aqueous MDEA. In this study, the model is further extended to estimate solubility of CO2 and H2S and their mixture in aqueous MDEA at high pressures with methane as a makeup gas....

  2. 750 GeV diphoton excesses in a realistic D-brane model

    Science.gov (United States)

    Li, Tianjun; Maxin, James A.; Mayes, Van E.; Nanopoulos, Dimitri V.

    2016-07-01

    We study the diphoton excesses near 750 GeV recently reported by the ATLAS and CMS collaborations within the context of a phenomenologically interesting intersecting/magnetized D-brane model on a toroidal orientifold. It is shown that the model contains a Standard Model singlet scalar as well as vector-like quarks and leptons. In addition, it is shown that the singlet scalar has Yukawa couplings with vector-like quarks and leptons such that it may be produced in proton-proton collisions via gluon fusion as well as decay to diphotons through loops involving the vector-like quarks. Moreover, the required vector-like quarks and leptons may appear in complete S U (5 ) multiplets so that gauge coupling unification may be maintained. Finally, it is shown that the diphoton signal may be accommodated within the model.

  3. Explaining muon magnetic moment and AMS-02 positron excess in a gauged horizontal symmetric model

    CERN Document Server

    Tomar, Gaurav

    2015-01-01

    We extended the standard model with a fourth generation of fermions to explain the discrepancy in the muon magnetic moment and to describe the positron excess observed by AMS-02 experiment. We introduce a gauged $SU(2)_{HV}$ horizontal symmetry between the muon and the 4th generation lepton families and identified the 4th generation right-handed neutrino as the dark matter with mass $\\sim 700$ GeV. The dark matter annihilates through $SU(2)_{HV}$ gauge boson into final states $(\\mu^+ \\mu^-)$ and $(\

  4. Galactic Gamma Ray Excess and Dark Matter Phenomenology in a $U(1)_{B-L}$ Model

    CERN Document Server

    Biswas, Anirban; Khan, Sarif

    2016-01-01

    In this work, we have considered a gauged $U(1)_{\\rm B-L}$ extension of the Standard Model (SM) with three right handed neutrinos for anomaly cancellation and two additional SM singlet complex scalars with non-trivial B-L charges. One of these is used to spontaneously break the $U(1)_{\\rm B-L}$ gauge symmetry, leading to Majorana masses for the neutrinos through the standard Type I seesaw mechanism, while the other becomes the dark matter (DM) candidate in the model. We test the viability of the model to simultaneously explain the DM relic density observed in the CMB data as well as the Galactic Centre (GC) $\\gamma$-ray excess seen by Fermi-LAT. We show that for DM masses in the range 40-55 GeV and for a wide range of $U(1)_{\\rm B-L}$ gauge boson masses, one can satisfy both these constraints if the additional neutral Higgs scalar has a mass around the resonance region. In studying the dark matter phenomenology and GC excess, we have taken into account theoretical as well as experimental constraints coming fr...

  5. Can an Asymptotically-Safe Conformal $U(1)'$ Model Address the LHC Diboson Excess?

    CERN Document Server

    Wang, Zhi-Wei; Steele, T G; Mann, R B

    2015-01-01

    We consider an asymptotically-safe conformal leptophobic $U(1)'$ model to address the diboson excess recently observed at LHC. A broad selection of UV boundary conditions corresponding to different asymptotic safety (AS) scenarios have been studied. We find the AS scenarios to have very strong predictive power, allowing unique determination of most of the parameters in the model. We obtain the interrelationships among the couplings, the unification scale $M_{UV}$ and the generations of quarks coupled to the $Z'$, and especially the correlation between $M_{UV}$ and the top quark Yukawa coupling $Y_t$. We find one of the AS boundary conditions provides a diboson excess of around 4 fb, which is close to the current best fit value. This requires a top quark Yukawa coupling $Y_t=0.954$ and a unification scale $M_{UV}=1.85\\times 10^{11}\\,\\rm{GeV}$, which is much lower than the Planck scale. In addition, this model also admits dark matter with a mass around $1\\,\\rm{TeV}$.

  6. Explaining the CMS excesses, baryogenesis and neutrino masses in $E_{6}$ motivated $U(1)_{N}$ model

    CERN Document Server

    Dhuria, Mansi; Sarkar, Utpal

    2016-01-01

    We study the superstring inspired $E_{6}$ model motivated $U(1)_{N}$ extension of the supersymmetric standard model to explore the possibility of explaining the recent excess CMS events and the baryon asymmetry of the universe in eight possible variants of the model. In light of the hints from short-baseline neutrino experiments at the existence of one or more light sterile neutrinos, we also study the neutrino mass matrices dictated by the field assignments and the discrete symmetries in these variants. We find that all the variants can explain the excess CMS events via the exotic slepton decay, while for a standard choice of the discrete symmetry four of the variants have the feature of allowing high scale baryogenesis (leptogenesis). For one other variant three body decay induced soft baryogenesis mechanism is possible which can induce baryon number violating neutron-antineutron oscillation. We also point out a new discrete symmetry which has the feature of ensuring proton stability and forbidding tree lev...

  7. Low Scale Composite Higgs Model and 1.8 $\\sim$ 2 TeV Diboson Excess

    CERN Document Server

    Bian, Ligong; Shu, Jing

    2015-01-01

    We consider a simple solution to explain the recent diboson excess observed by ATALS and CMS Collaborations in models with custodial symmetry $SU(2)_L \\times SU(2)_R \\rightarrow SU(2)_c$. The $SU(2)_L$ triplet vector boson $\\rho$ with mass range of $1.8 \\sim 2$ TeV would be produced through the Drell-Yan process with sizable diboson decay branching to account for the excess. The other $SU(2)_L \\times SU(2)_R$ bidoublet axial vector boson $a$ would cancel all deviations of electroweak obervables induced by $\\rho$ even if the SM fermions mix with some heavy vector like (composite) fermions which couple to $\\rho$ ("non-universally partially composite"), therefore allows arbitrary couplings between each SM fermion and $\\rho$. We present our model in the "General Composite Higgs" framework with $SO(5) \\times U(1)_X \\rightarrow SO(4) \\times U(1)_X$ breaking at scale $f$ and demand the first Weinberg sum rule and positive gauge boson form factors as the theoretical constraints. We find that our model can fit the dib...

  8. Simplified Dark Matter Models for the Galactic Center Gamma-Ray Excess

    Energy Technology Data Exchange (ETDEWEB)

    Berlin, Asher; Hooper, Dan; McDermott, Samuel D.

    2014-06-01

    Motivated by the gamma-ray excess observed from the region surrounding the Galactic Center, we explore particle dark matter models that could potentially account for the spectrum and normalization of this signal. Taking a model-independent approach, we consider an exhaustive list of tree-level diagrams for dark matter annihilation, and determine which could account for the observed gamma-ray emission while simultaneously predicting a thermal relic abundance equal to the measured cosmological dark matter density. We identify a wide variety of models that can meet these criteria without conflicting with existing constraints from direct detection experiments or the Large Hadron Collider (LHC). The prospects for detection in near future dark matter experiments and/or the upcoming 14 TeV LHC appear quite promising.

  9. The $750$ GeV Diphoton Excesses in a Realistic D-brane Model

    CERN Document Server

    Li, Tianjun; Mayes, Van E; Nanopoulos, Dimitri V

    2016-01-01

    We study the diphoton excesses near $750$ GeV recently reported by the ATLAS and CMS collaborations within the context of a phenomenologically interesting intersecting/magnetized D-brane model on a toroidal orientifold. It is shown that the model contains a SM singlet scalar as well as vector-like quarks and leptons. In addition, it is shown that the singlet scalar has Yukawa couplings with vector-like quarks and leptons such that it may be produced in proton-proton collisions via gluon fusion as well as decay to diphotons through loops involving the vector-like quarks. Moreover, the required vector-like quarks and leptons may appear in complete $SU(5)$ multiplets so that gauge coupling unification may be maintained. Finally, it is shown that the diphoton signal may be explained within the model.

  10. Interpreting the 750 GeV diphoton excess in the minimal dilaton model

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Junjie [Wuhan University, Center for Theoretical Physics, School of Physics and Technology, Wuhan (China); Henan Normal University, Department of Physics, Xinxiang (China); Shang, Liangliang [Henan Normal University, Department of Physics, Xinxiang (China); Su, Wei; Zhang, Yang [Institute of Theoretical Physics, Academia Sinica, State Key Laboratory of Theoretical Physics, Beijing (China); Zhu, Jinya [Wuhan University, Center for Theoretical Physics, School of Physics and Technology, Wuhan (China)

    2016-05-15

    We try to interpret the 750 GeV diphoton excess in the minimal dilaton model, which extends the SM by adding one linearized dilaton field and vector-like fermions. We first show by analytic formulas in this framework that the production rates of the γγ, gg, Zγ, ZZ, WW*, t anti t, and hh signals at the 750 GeV resonance are only sensitive to the dilaton-Higgs mixing angle θ{sub S} and the parameter η ≡ vN{sub X}/f, where f is the dilaton decay constant and N{sub X} denotes the number of the fermions. Then we scan the two parameters by considering various theoretical and experimental constraints to find the solutions to the diphoton excess. We conclude that the model can predict the central value of the diphoton rate without conflicting with any constraints. The signatures of our explanation at the LHC Run II and the vacuum stability at high energy scale are also discussed. (orig.)

  11. Interpreting the 750 GeV diphoton excess in the minimal dilaton model

    Science.gov (United States)

    Cao, Junjie; Shang, Liangliang; Su, Wei; Zhang, Yang; Zhu, Jinya

    2016-05-01

    We try to interpret the 750 GeV diphoton excess in the minimal dilaton model, which extends the SM by adding one linearized dilaton field and vector-like fermions. We first show by analytic formulas in this framework that the production rates of the γ γ , gg, Zγ , ZZ, WW^*, tbar{t}, and hh signals at the 750 GeV resonance are only sensitive to the dilaton-Higgs mixing angle θ _S and the parameter η ≡ v N_X/f, where f is the dilaton decay constant and N_X denotes the number of the fermions. Then we scan the two parameters by considering various theoretical and experimental constraints to find the solutions to the diphoton excess. We conclude that the model can predict the central value of the diphoton rate without conflicting with any constraints. The signatures of our explanation at the LHC Run II and the vacuum stability at high energy scale are also discussed.

  12. Interpreting the 750 GeV diphoton excess in the Minimal Dilaton Model

    CERN Document Server

    Cao, Junjie; Su, Wei; Zhang, Yang; Zhu, Jingya

    2016-01-01

    We try to interpret the 750 GeV diphoton excess in the Minimal Dilaton Model, which extends the SM by adding one linearized dilaton field and vector-like fermions. We first show by analytic formulae in this framework that the production rates of the $\\gamma \\gamma$, $gg$, $Z\\gamma$, $ZZ$, $WW$, $t\\bar{t}$ and $hh$ signals at the $750 {\\rm GeV}$ resonance are only sensitive to the dilaton-Higgs mixing angle $\\theta_S$ and the parameter $\\eta \\equiv v N_X/f$, where $f$ is the dilaton decay constant and $N_X$ denotes the number of the fermions. Then we scan the two parameters by considering various theoretical and experimental constraints to find the solutions to the diphoton excess. We conclude that the model can predict the central value of the diphoton rate without conflicting with any constraints. The signatures of our explanation at the LHC Run II and the stability of the vacuum at high energy scale are also discussed.

  13. Explaining the CMS $eejj$ and $e \\slashed {p}_T jj$ Excess and Leptogenesis in Superstring Inspired $E_6$ Models

    CERN Document Server

    Dhuria, Mansi; Rangarajan, Raghavan; Sarkar, Utpal

    2015-01-01

    We show that superstring inspired $E_6$ models can explain both the recently detected excess $eejj$ and $e \\slashed p_T jj$ signals at CMS, and also allow for leptogenesis. Working in a R-parity conserving low energy supersymmetric effective model, we show that the excess CMS events can be produced via the decay of exotic sleptons in alternative left-right symmetric models of $E_6$, which can also accommodate leptogenesis at a high scale. On the other hand, either the $eejj$ excess or the $e \\slashed p_T jj$ excess can be produced via the decays of right handed gauge bosons, but some of these scenarios may not accommodate letptogenesis as there will be strong $B-L$ violation at low energy, which, along with the anomalous fast electroweak $B+L$ violation, will wash out all baryon asymmetry. Baryogenesis below the electroweak scale may then need to be implemented in these models.

  14. LHC 750 GeV Diphoton excess in a radiative seesaw model

    CERN Document Server

    Kanemura, Shinya; Okada, Hiroshi; Orikasa, Yuta; Park, Seong Chan; Watanabe, Ryoutaro

    2015-01-01

    We investigate a possibility for explaining the recently announced 750 GeV diphoton excess by the ATLAS and the CMS experiments at the CERN LHC in a model with multiple doubly-charged particles, which was originally suggested for explaining tiny neutrino masses through a three-loop effect in a natural way. The enhanced radiatively generated effective coupling of a new singlet scalar $S$ with diphoton, with multiple charged particles in the loop, enlarges the production rate of $S$ in $pp \\to S+X$ via photon fusion process and also the decay width $\\Gamma(S \\to \\gamma\\gamma)$ even without assuming a tree level production mechanism. Very interestingly, we find that the branching ratio $\\mathcal{B}(S \\to \\gamma\\gamma)$ is $\\simeq 60\\%$ fixed by quantum numbers and the model is consistent with all the constraints from $8\\,\\text{TeV}$ LHC data.

  15. LHC 750 GeV diphoton excess in a radiative seesaw model

    Science.gov (United States)

    Kanemura, Shinya; Nishiwaki, Kenji; Okada, Hiroshi; Orikasa, Yuta; Chan Park, Seong; Watanabe, Ryoutaro

    2016-12-01

    We investigate a possibility for explaining the recently announced 750 GeV diphoton excess by the ATLAS and CMS experiments at the CERN LHC in a model with multiple doubly charged particles, that was originally suggested for explaining tiny neutrino masses through a three-loop effect in a natural way. The enhanced radiatively generated effective coupling of a new singlet scalar S with diphoton with multiple charged particles in the loop enlarges the production rate of S in pp→S+X via a photon fusion process and also the decay width Γ(S→γγ) even without assuming a tree-level production mechanism. We provide detailed analysis on the cases with or without allowing mixing between S and the standard model Higgs doublet.

  16. Models of LHC Diphoton Excesses Valid up to the Planck scale

    CERN Document Server

    Hamada, Yuta; Kawana, Kiyoharu; Tsumura, Koji

    2016-01-01

    We discuss a possibility to explain the LHC diphoton excesses at $750$GeV by the new scalar $X$ that couples to the gauge bosons through the loop of new massive particles with Standard Model charges. We assume that the new particles decay into the Standard model particles at the tree level. We systematically examine the models that preserve the vacuum stability and the perturbativity up to the Planck scale. When we take scalars for the new particles, we find that only a few diquark and dilepton models can explain the observed diphoton cross section without conflicting the experimental mass bounds. When we take vector-like fermions for the new particles, we find rather different situations depending on whether their couplings to $X$ are scalar or pseudoscalar type. In the former case, a few models are allowed if we introduce only one species of fermions. The more fermions we introduce, the more models are allowed. In the later case, the most of the models are allowed because of the large coupling between $X$ a...

  17. Explaining the diphoton excess in Alternative Left-Right Symmetric Model

    CERN Document Server

    Hati, Chandan

    2016-01-01

    We propose a possible explanation of the recent diphoton excess reported by ATLAS and CMS collaborations, at around 750 GeV diphoton invariant mass, within the framework of $E_{6}$ motivated Alternative Left-Right Symmetric Model (ALRSM), which is capable of addressing the $B$ decay anomalies in the flavor sector, the $eejj$ and $e$ missing $p_{T}jj$ excesses reported by CMS in run 1 of LHC and has the feature of high scale leptogenesis. We find that gluon-gluon fusion can give the observed production rate of the 750 GeV resonance, $\\tilde{n}$, through a loop of scalar leptoquarks ($\\tilde{h}^{(c)}$) with mass below a few TeV range, while $\\tilde{n}$ can subsequently decay into $\\gamma\\gamma$ final state via loops of $\\tilde{h}^{(c)}$ and $\\tilde{E}^{(c)}$. Interestingly, the $\\tilde{E}^{(c)}$ loop can enhance the diphoton branching ratio significantly to successfully explain the observed cross section of the diphoton signal.

  18. Cosmic-Ray Models of the Ridge-Like Excess of Gamma Rays in the Galactic Center

    CERN Document Server

    Macias, Oscar; Gordon, Chris; Profumo, Stefano

    2014-01-01

    The High-Energy Stereoscopic System (HESS) has detected diffuse TeV emission correlated with the distribution of molecular gas along the Galactic Ridge at the Galactic Center. Diffuse, non-thermal emission is also seen by the Fermi large area telescope (Fermi-LAT) in the GeV range and by radio telescopes in the GHz range. Additionally, there is a distinct, spherically symmetric excess of gamma rays seen by Fermi-LAT in the GeV range. A cosmic ray flare, occurring in the Galactic Center, $10^4$ years ago has been proposed to explain the TeV Galactic Ridge (Aharonian et al. 2006). An alternative, steady-state model explaining all three data sets (TeV, GeV, and radio) invokes purely leptonic processes (Yusef-Zadeh et al. 2013). We show that the flare model from the Galactic Center also provides an acceptable fit to the GeV and radio data, provided the diffusion coefficient is energy independent. However, if Kolmogorov-type turbulence is assumed for the diffusion coefficient, we find that two flares are needed, o...

  19. Hidden Sector Dark Matter Models for the Galactic Center Gamma-Ray Excess

    Energy Technology Data Exchange (ETDEWEB)

    Berlin, Asher [Chicago U.; Gratia, Pierre [Chicago U.; Hooper, Dan [Chicago U., Astron. Astrophys. Ctr.; McDermott, Samuel D. [Michigan U., MCTP

    2014-07-24

    The gamma-ray excess observed from the Galactic Center can be interpreted as dark matter particles annihilating into Standard Model fermions with a cross section near that expected for a thermal relic. Although many particle physics models have been shown to be able to account for this signal, the fact that this particle has not yet been observed in direct detection experiments somewhat restricts the nature of its interactions. One way to suppress the dark matter's elastic scattering cross section with nuclei is to consider models in which the dark matter is part of a hidden sector. In such models, the dark matter can annihilate into other hidden sector particles, which then decay into Standard Model fermions through a small degree of mixing with the photon, Z, or Higgs bosons. After discussing the gamma-ray signal from hidden sector dark matter in general terms, we consider two concrete realizations: a hidden photon model in which the dark matter annihilates into a pair of vector gauge bosons that decay through kinetic mixing with the photon, and a scenario within the generalized NMSSM in which the dark matter is a singlino-like neutralino that annihilates into a pair of singlet Higgs bosons, which decay through their mixing with the Higgs bosons of the MSSM.

  20. Modelling emissions from natural gas flaring

    Directory of Open Access Journals (Sweden)

    G. Ezaina Umukoro

    2017-04-01

    Full Text Available The world today recognizes the significance of environmental sustainability to the development of nations. Hence, the role oil and gas industry plays in environmental degrading activities such as gas flaring is of global concern. This study presents material balance equations and predicts results for non-hydrocarbon emissions such as CO2, CO, NO, NO2, and SO2 etc. from flaring (combustion of 12 natural gas samples representing composition of natural gas of global origin. Gaseous emission estimates and pattern were modelled by coding material balance equations for six reaction types and combustion conditions with a computer program. On the average, anticipated gaseous emissions from flaring natural gas with an average annual global flaring rate 126 bcm per year (between 2000 and 2011 in million metric tonnes (mmt are 560 mmt, 48 mmt, 91 mmt, 93 mmt and 50 mmt for CO2, CO, NO, NO2 and SO2 respectively. This model predicted gaseous emissions based on the possible individual combustion types and conditions anticipated in gas flaring operation. It will assist in the effort by environmental agencies and all concerned to track and measure the extent of environmental pollution caused by gas flaring operations in the oil and gas industry.

  1. Adsorption Model for Off-Gas Separation

    Energy Technology Data Exchange (ETDEWEB)

    Veronica J. Rutledge

    2011-03-01

    The absence of industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other countries. Thus, it is essential to model complex series of unit operations to simulate, understand, and predict inherent transient behavior and feedback loops. A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes will provide substantial cost savings and many technical benefits. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed in gPROMS software. Inputs include gas stream constituents, sorbent, and column properties, equilibrium and kinetic data, and inlet conditions. It models dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions for a multiple component gas stream. The simulation outputs component concentrations along the column length as a function of time from which the breakthrough data is obtained. It also outputs temperature along the column length as a function of time and pressure drop along the column length. Experimental data will be input into the adsorption model to develop a model specific for iodine adsorption on silver mordenite as well as model(s) specific for krypton and xenon adsorption. The model will be validated with experimental breakthrough curves. Another future off-gas modeling goal is to develop a model for the unit operation absorption. The off-gas models will be made available via the server or web for evaluation by customers.

  2. A thermodynamic model for coal gas outbursts

    Energy Technology Data Exchange (ETDEWEB)

    Toth, J.; Lakatos, J. (Hungarian Academy of Sciences (Hungary). Research Lab. for Mining Chemistry)

    1994-06-01

    A thermodynamic model-scheme has been formulated based on the laboratory modelling results of gas/coal outbursts and sorption properties of the gas/coal systems. The sorption properties include the inversion of sorption isotherms, the maximum characters of isobar functions, the activated sorption of gases in coal (methane, carbon-dioxide, nitrogen, ethane) and two equilibria (a metastable and a stable one) in the coal/gas systems. The basic idea of the model is that between the two equilibria exists a potential barrier. When this barrier is crossed by the gas sorbed in the bulk phase of coal a considerable amount of energy is released. This energy may be stored in a definite volume of the rock and if it becomes greater than the compressive strength of the coal the outburst takes place. 4 refs., 5 figs.

  3. Measurements and analysis of excess enthalpies of ester + n-alkane using the UNIFAC model

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, J. (Escuela Superior de Ingenieros Industriales, Las Palmas (Spain). Catedra de Termodinamica y Fisicoquimica); Legido, J.L.; Fernandez, J.; Pias, L.; Paz Andrade, M.I. (Universidad de Santiago de Compostela (Spain). Dept. de Fisica Aplicada)

    1991-02-01

    We present new experimental data of the excess molar enthalpies at 298.15 K for eighteen different binary mixtures of nine methyl alkanoates (ethanoate to decanoate) with n-heptane and n-undecane. The results show that all the systems are endothermic, h{sup E} values increase with the length of the n-alkane and decrease with the length of the methyl ester. The data have been analysed with a version of the UNIFAC model, and the parameters corresponding to the CH{sub 2}/COOC interaction have been recalculated using a larger base of experimental data. New values for the CH{sub 2}/COO interaction parameters have been obtained. (orig.).

  4. The Observed Diphoton Excess in F-theory Inspired Heterotic String-Derived Model

    CERN Document Server

    Ashfaque, Johar M

    2016-01-01

    The production and the subsequent decay of the SM singlet via heavy vector--like colour triplets and electroweak doublets in one--loop diagrams can shed light on the recent observation of diphoton excess at the LHC. In this paper, the $E_6$ GUT is considered in the F-theory setting where the $E_6$ is broken by making use of the spectral cover construction and by turning on the hypercharge gauge flux. This paper is based on the results presented in \\cite{Athanasopoulos:2014bba, Faraggi:2016xnm, Ashfaque:2016jha} which will be reviewed briefly. Here, by following the F-theory approach, akin to \\cite{Karozas:2016hcp, Leontaris:2016wsy, Das:2016xuc}, we present a study of the flipped $SO(10)$ model embedded completely in the $E_{6}$ GUT but with a different accommodation of the SM representations in the ${\\bf{27}}$ of $E_{6}$.

  5. Symmetrization of excess Gibbs free energy: A simple model for binary liquid mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Castellanos-Suarez, Aly J., E-mail: acastell@ivic.gob.v [Centro de Estudios Interdisciplinarios de la Fisica (CEIF), Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 21827, Caracas 1020A (Venezuela, Bolivarian Republic of); Garcia-Sucre, Maximo, E-mail: mgs@ivic.gob.v [Centro de Estudios Interdisciplinarios de la Fisica (CEIF), Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 21827, Caracas 1020A (Venezuela, Bolivarian Republic of)

    2011-03-15

    A symmetric expression for the excess Gibbs free energy of liquid binary mixtures is obtained using an appropriate definition for the effective contact fraction. We have identified a mechanism of local segregation as the main cause of the contact fraction variation with the concentration. Starting from this mechanism we develop a simple model for describing binary liquid mixtures. In this model two parameters appear: one adjustable, and the other parameter depending on the first one. Following this procedure we reproduce the experimental data of (liquid + vapor) equilibrium with a degree of accuracy comparable to well-known more elaborated models. The way in which we take into account the effective contacts between molecules allows identifying the compound which may be considered to induce one of the following processes: segregation, anti-segregation and dispersion of the components in the liquid mixture. Finally, the simplicity of the model allows one to obtain only one resulting interaction energy parameter, which makes easier the physical interpretation of the results.

  6. The 750 GeV diphoton LHC excess and Extra Z's in Heterotic-String Derived Models

    CERN Document Server

    Faraggi, Alon E

    2016-01-01

    The ATLAS and CMS collaborations recently recorded possible di-photon excess at 750 GeV and a less significant di-boson excess around 1.9 TeV. Such excesses may be produced in heterotic-string derived Z' models, where the di-photon excess may be connected with the Standard Model singlet scalar responsible for the Z' symmetry breaking, whereas the di-boson excess arises from production of the extra vector boson. Additional vector-like states in the string Z' model are instrumental to explain the relatively large width of the di-photon events and mandated by anomaly cancellation to be in the vicinity of the Z' breaking scale. Wilson line breaking of the non-Abelian gauge symmetries in the string models naturally gives rise to dark matter candidates. Future collider experiments will discriminate between the high-scale heterotic-string models, which preserve the perturbative unification paradigm indicated by the Standard Model data, versus the low scale string models. We also discuss the possibility for the produ...

  7. Combustion modeling in advanced gas turbine systems

    Energy Technology Data Exchange (ETDEWEB)

    Smoot, L.D.; Hedman, P.O.; Fletcher, T.H. [Brigham Young Univ., Provo, UT (United States)] [and others

    1995-10-01

    The goal of the U.S. Department of Energy`s Advanced Turbine Systems (ATS) program is to help develop and commercialize ultra-high efficiency, environmentally superior, and cost competitive gas turbine systems for base-load applications in the utility, independent power producer, and industrial markets. Combustion modeling, including emission characteristics, has been identified as a needed, high-priority technology by key professionals in the gas turbine industry.

  8. Formation of natural gas hydrates in marine sediments 1. Conceptual model of gas hydrate growth conditioned by host sediment properties

    Science.gov (United States)

    Clennell, M.B.; Hovland, M.; Booth, J.S.; Henry, P.; Winters, W.J.

    1999-01-01

    The stability of submarine gas hydrates is largely dictated by pressure and temperature, gas composition, and pore water salinity. However, the physical properties and surface chemistry of deep marine sediments may also affect the thermodynamic state, growth kinetics, spatial distributions, and growth forms of clathrates. Our conceptual model presumes that gas hydrate behaves in a way analogous to ice in a freezing soil. Hydrate growth is inhibited within fine-grained sediments by a combination of reduced pore water activity in the vicinity of hydrophilic mineral surfaces, and the excess internal energy of small crystals confined in pores. The excess energy can be thought of as a "capillary pressure" in the hydrate crystal, related to the pore size distribution and the state of stress in the sediment framework. The base of gas hydrate stability in a sequence of fine sediments is predicted by our model to occur at a lower temperature (nearer to the seabed) than would be calculated from bulk thermodynamic equilibrium. Capillary effects or a build up of salt in the system can expand the phase boundary between hydrate and free gas into a divariant field extending over a finite depth range dictated by total methane content and pore-size distribution. Hysteresis between the temperatures of crystallization and dissociation of the clathrate is also predicted. Growth forms commonly observed in hydrate samples recovered from marine sediments (nodules, and lenses in muds; cements in sands) can largely be explained by capillary effects, but kinetics of nucleation and growth are also important. The formation of concentrated gas hydrates in a partially closed system with respect to material transport, or where gas can flush through the system, may lead to water depletion in the host sediment. This "freeze-drying" may be detectable through physical changes to the sediment (low water content and overconsolidation) and/or chemical anomalies in the pore waters and metastable

  9. Prairie voles as a novel model of socially facilitated excessive drinking.

    Science.gov (United States)

    Anacker, Allison M J; Loftis, Jennifer M; Kaur, Simranjit; Ryabinin, Andrey E

    2011-01-01

    Social relationships strongly affect alcohol drinking in humans. Traditional laboratory rodents do not exhibit social affiliations with specific peers, and cannot adequately model how such relationships impact drinking. The prairie vole is a socially monogamous rodent used to study social bonds. The present study tested the prairie vole as a potential model for the effects of social affiliations on alcohol drinking. Same-sex adult sibling prairie voles were paired for five days, and then either separated into individual cages, or housed in pairs. Starting at the time of separation, the voles received unlimited access to alcohol in a two-bottle choice test versus water. Pair-housed siblings exhibited higher preference for alcohol, but not saccharin, than singly housed voles. There was a significant correlation between the amount of alcohol consumed by each member of a pair when they were housed together (r = 0.79), but not when housed apart (r = 0.20). Following automated analysis of circadian patterns of fluid consumption indicating peak fluid intake before and after the dark phase, a limited access two-hour two-bottle choice procedure was established. Drinking in this procedure resulted in physiologically relevant blood ethanol concentrations and increased Fos immunoreactivity in perioculomotor urocortin containing neurons (but not in nucleus accumbens or central nucleus of the amygdala). The high ethanol preference and sensitivity to social manipulation indicate that prairie voles can serve to model social influences on excessive drinking.

  10. E6 inspired composite Higgs model and 750 GeV diphoton excess

    CERN Document Server

    Nevzorov, R

    2016-01-01

    In the E6 inspired composite Higgs model (E6CHM) the strongly interacting sector possesses an SU(6)\\times U(1)_B\\times U(1)_L global symmetry. Near scale f\\gtrsim 10 TeV the SU(6) symmetry is broken down to its SU(5) subgroup, that involves the standard model (SM) gauge group. This breakdown of SU(6) leads to a set of pseudo--Nambu--Goldstone bosons (pNGBs) including a SM--like Higgs and a SM singlet pseudoscalar A. Because of the interactions between A and exotic fermions, which ensure the approximate unification of the SM gauge couplings and anomaly cancellation in this model, the couplings of the pseudoscalar A to gauge bosons get induced. As a result, the SM singlet pNGB state A with mass around 750 GeV may give rise to sufficiently large cross section of pp\\to \\gamma\\gamma that can be identified with the recently observed diphoton excess.

  11. Minimal Superstrings and Loop Gas Models

    CERN Document Server

    Gaiotto, D; Takayanagi, T; Gaiotto, Davide; Rastelli, Leonardo; Takayanagi, Tadashi

    2005-01-01

    We reformulate the matrix models of minimal superstrings as loop gas models on random surfaces. In the continuum limit, this leads to the identification of minimal superstrings with certain bosonic string theories, to all orders in the genus expansion. RR vertex operators arise as operators in a Z_2 twisted sector of the matter CFT. We show how the loop gas model implements the sum over spin structures expected from the continuum RNS formulation. Open string boundary conditions are also more transparent in this language.

  12. On modelling the market for natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Mathiesen, Lars

    2001-12-01

    Several features may separately or in combination influence conduct and performance of an industry, e.g. the numbers of sellers or buyers, the degree of economies of scale in production and distribution, the temporal and spatial dimensions, etc. Our main focus is on how to model market power. In particular, we demonstrate the rather different solutions obtained from the price-taking behavior versus the oligopolistic Coumot behavior. We also consider two approaches to model the transportation of natural gas. Finally, there is a brief review of previous modeling efforts of the European natural gas industry. (author)

  13. Gas Modelling in the Disc of HD 163296

    Science.gov (United States)

    Tilling, I.; Woitke, P.; Meeus, G.; Mora, A.; Montesinos, B.; Riviere-Marichalar, P.; Eiroa, C.; Thi, W. -F.; Isella, A.; Roberge, A.; hide

    2011-01-01

    We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of approx. 4Myr, with evidence of a circumstellar disc extending out to approx. 540AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (Gas in Protoplanetary Systems), consisting of a detection of the [Oi] 63 m line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the CO-12 3-2, 2-1 and CO-13 J=1-0 line transitions, as well as the H2 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, depending on the assumptions made. We note that the line fluxes are sensitive in general to the degree of dust settling in the disc, with an increase in line flux for settled models. This is most pronounced in lines which are formed in the warm gas in the inner disc, but the low excitation molecular lines are also affected. This has serious implications for attempts to derive the disc gas mass from line observations. We derive fractional PAH abundances between 0.007 and 0.04 relative to ISM levels. Using a stellar and UV excess input spectrum based on a detailed analysis of observations, we find that the all observations are consistent with the previously assumed disc geometry

  14. Coupled heat/mass-balance model for analyzing correlation between excess AlF3 concentration and aluminum electrolyte temperature

    Institute of Scientific and Technical Information of China (English)

    HUANG Yong-bo; QU Xiang-dong; ZHOU Jie-min

    2009-01-01

    The influence of aluminum electrolyte component on its temperature is an important issue within the field of aluminum reduction with pre-baked cells. The characteristic correlation between excess AlF3 concentration and aluminum electrolyte temperature was explored through the modeling of heat and mass transfer processes in industrial pre-baked aluminum reduction cells. A coupled heat/mass-balance model was derived theoretically from the mass and energy balance of an electrolysis cell, and then was simplified properly into a practical expression. The model demonstrates that if environmental temperature and Al2O3 concentration keep constant, the excess AlF3 concentration decreases with the aluminum electrolyte temperature linearly and its decrease rate is dependent on the heat transfer property of aluminum electrolyte, side wall and cell shell. Secondly, experiments were conducted on site with two industrial cells in an aluminum electrolysis plant. Excess AlF3 concentration and aluminum electrolyte temperature were obtained simultaneously together with other parameters such as Al2O3, CaF2, MgF2 and LiF concentrations. Results show that the maximum absolute error between the tested value and the calculated value of excess AlF3 concentration using the proposed model is less than 2%. This reveals that the coupled heat/mass-balance model can appropriately characterize the correlation between excess AlF3 concentration and aluminum electrolyte temperature with good accuracy and practicability.

  15. The dark connection between the Canis Major dwarf, the Monoceros ring, the gas flaring, the rotation curve and the EGRET excess of diffuse Galactic Gamma Rays

    CERN Document Server

    de Boer, Wim; Weber, M; Sander, C; Zhukov, V; Kazakov, D

    2007-01-01

    The excess of diffuse galactic gamma rays above 1 GeV, as observed by the EGRET telescope on the NASA Compton Gamma Ray Observatory, shows all the key features from Dark Matter (DM) annihilation: (i) the energy spectrum of the excess is the same in all sky directions and is consistent with the gamma rays expected for the annihilation of WIMPs with a mass between 50-100 GeV; (ii) the intensity distribution of the excess in the sky is used to determine the halo profile, which was found to correspond to the usual profile from N-body simulations with additional substructure in the form of two doughnut-shaped structures at radii of 4 and 13 kpc; (iii) recent N-body simulations of the tidal disruption of the Canis Major dwarf galaxy show that it is a perfect progenitor of the ringlike Monoceros tidal stream of stars at 13 kpc with ring parameters in agreement with the EGRET data; (iiii) the mass of the outer ring is so large, that its gravitational effects influence both the gas flaring and the rotation curve of th...

  16. Geochemical modeling of magmatic gas scrubbing

    Directory of Open Access Journals (Sweden)

    B. Gambardella

    2005-06-01

    Full Text Available The EQ3/6 software package, version 7.2 was successfully used to model scrubbing of magmatic gas by pure water at 0.1 MPa, in the liquid and liquid-plus-gas regions. Some post-calculations were necessary to account for gas separation effects. In these post-calculations, redox potential was considered to be fixed by precipitation of crystalline a-sulfur, a ubiquitous and precocious process. As geochemical modeling is constrained by conservation of enthalpy upon water-gas mixing, the enthalpies of the gas species of interest were reviewed, adopting as reference state the liquid phase at the triple point. Our results confirm that significant emissions of highly acidic gas species (SO2(g, HCl(g, and HF(g are prevented by scrubbing, until dry conditions are established, at least locally. Nevertheless important outgassing of HCl(g can take place from acid, HCl-rich brines. Moreover, these findings support the rule of thumb which is generally used to distinguish SO2-, HCl-, and HF-bearing magmatic gases from SO2-, HCl-, and HF-free hydrothermal gases.

  17. Excessive somnolence

    Directory of Open Access Journals (Sweden)

    Stella Tavares

    Full Text Available Excessive somnolence can be quite a incapacitating manifestation, and is frequently neglected by physicians and patients. This article reviews the determinant factors, the evaluation and quantification of diurnal somnolence, and the description and treatment of the main causes of excessive somnolence.

  18. Time-Lagging Interplay Effect and Excess Risk of Meteorological/Mosquito Parameters and Petrochemical Gas Explosion on Dengue Incidence

    OpenAIRE

    Ko Chang; Chaur-Dong Chen; Chien-Ming Shih; Tzu-Chi Lee; Ming-Tsang Wu; Deng-Chyang Wu; Yen-Hsu Chen; Chih-Hsing Hung; Meng-Chieh Wu; Chun-Chi Huang; Chien-Hung Lee; Chi-Kung Ho

    2016-01-01

    In Kaohsiung, a metropolitan city in Taiwan at high risk of dengue epidemic, weather factors combined with an accidental petrochemical gas explosion (PGE) may affect mosquito‒human dynamics in 2014. Generalized estimating equations with lagged-time Poisson regression analyses were used to evaluate the effect of meteorological/mosquito parameters and PGE on dengue incidences (2000–2014) in Kaohsiung. Increased minimum temperatures rendered a 2- and 3-month lagging interactive effect on higher ...

  19. Individual Diet Modeling Shows How to Balance the Diet of French Adults with or without Excessive Free Sugar Intakes

    Directory of Open Access Journals (Sweden)

    Anne Lluch

    2017-02-01

    Full Text Available Dietary changes needed to achieve nutritional adequacy for 33 nutrients were determined for 1719 adults from a representative French national dietary survey. For each individual, an iso-energy nutritionally adequate diet was generated using diet modeling, staying as close as possible to the observed diet. The French food composition table was completed with free sugar (FS content. Results were analyzed separately for individuals with FS intakes in their observed diets ≤10% or >10% of their energy intake (named below FS-ACCEPTABLE and FS-EXCESS, respectively. The FS-EXCESS group represented 41% of the total population (average energy intake of 14.2% from FS. Compared with FS-ACCEPTABLE individuals, FS-EXCESS individuals had diets of lower nutritional quality and consumed more energy (2192 vs. 2123 kcal/day, particularly during snacking occasions (258 vs. 131 kcal/day (all p-values < 0.01. In order to meet nutritional targets, for both FS-ACCEPTABLE and FS-EXCESS individuals, the main dietary changes in optimized diets were significant increases in fresh fruits, starchy foods, water, hot beverages and plain yogurts; and significant decreases in mixed dishes/sandwiches, meat/eggs/fish and cheese. For FS-EXCESS individuals only, the optimization process significantly increased vegetables and significantly decreased sugar-sweetened beverages, sweet products and fruit juices. The diets of French adults with excessive intakes of FS are of lower nutritional quality, but can be optimized via specific dietary changes.

  20. Effects of excessive equatorial cold tongue bias on the projections of tropical Pacific climate change. Part I: the warming pattern in CMIP5 multi-model ensemble

    Science.gov (United States)

    Li, Gen; Xie, Shang-Ping; Du, Yan; Luo, Yiyong

    2016-12-01

    The excessive cold tongue error in the equatorial Pacific has persisted in several generations of climate models. Based on the historical simulations and Representative Concentration Pathway (RCP) 8.5 experiments in the Coupled Model Intercomparison Project phase 5 (CMIP5) multi-model ensemble (MME), this study finds that models with an excessive westward extension of cold tongue and insufficient equatorial western Pacific precipitation tend to project a weaker east-minus-west gradient of sea surface temperature (SST) warming along the equatorial Pacific under increased greenhouse gas (GHG) forcing. This La Niña-like error of tropical Pacific SST warming is consistent with our understanding of negative SST-convective feedback over the western Pacific warm pool. Based on this relationship between the present simulations and future projections, the present study applies an "observational constraint" of equatorial western Pacific precipitation to calibrate the projections of tropical Pacific climate change. After the corrections, CMIP5 models robustly project an El Niño-like warming pattern, with a MME mean increase by a factor of 2.3 in east-minus-west gradient of equatorial Pacific SST warming and reduced inter-model uncertainty. Corrections in projected changes in tropical precipitation and atmospheric circulation are physically consistent. This study suggests that a realistic cold tongue simulation would lead to a more reliable tropical Pacific climate projection.

  1. Effects of excessive equatorial cold tongue bias on the projections of tropical Pacific climate change. Part I: the warming pattern in CMIP5 multi-model ensemble

    Science.gov (United States)

    Li, Gen; Xie, Shang-Ping; Du, Yan; Luo, Yiyong

    2016-02-01

    The excessive cold tongue error in the equatorial Pacific has persisted in several generations of climate models. Based on the historical simulations and Representative Concentration Pathway (RCP) 8.5 experiments in the Coupled Model Intercomparison Project phase 5 (CMIP5) multi-model ensemble (MME), this study finds that models with an excessive westward extension of cold tongue and insufficient equatorial western Pacific precipitation tend to project a weaker east-minus-west gradient of sea surface temperature (SST) warming along the equatorial Pacific under increased greenhouse gas (GHG) forcing. This La Niña-like error of tropical Pacific SST warming is consistent with our understanding of negative SST-convective feedback over the western Pacific warm pool. Based on this relationship between the present simulations and future projections, the present study applies an "observational constraint" of equatorial western Pacific precipitation to calibrate the projections of tropical Pacific climate change. After the corrections, CMIP5 models robustly project an El Niño-like warming pattern, with a MME mean increase by a factor of 2.3 in east-minus-west gradient of equatorial Pacific SST warming and reduced inter-model uncertainty. Corrections in projected changes in tropical precipitation and atmospheric circulation are physically consistent. This study suggests that a realistic cold tongue simulation would lead to a more reliable tropical Pacific climate projection.

  2. Fatigue modelling for gas nitriding

    Directory of Open Access Journals (Sweden)

    H. Weil

    2016-10-01

    Full Text Available The present study aims to develop an algorithm able to predict the fatigue lifetime of nitrided steels. Linear multi-axial fatigue criteria are used to take into account the gradients of mechanical properties provided by the nitriding process. Simulations on rotating bending fatigue specimens are made in order to test the nitrided surfaces. The fatigue model is applied to the cyclic loading of a gear from a simulation using the finite element software Ansys. Results show the positive contributions of nitriding on the fatigue strength

  3. A Disk Wind Model for the Near-Infrared Excess Emission in Protostars

    CERN Document Server

    Bans, Alissa

    2012-01-01

    Protostellar systems, ranging from low-luminosity T Tauri and Herbig Ae stars to high-luminosity Herbig Be stars, exhibit a near-infrared (NIR) excess in their spectra that is dominated by a bump in the monochromatic luminosity with a peak near 3 microns. The bump can be approximated by a thermal emission component of temperature 1500 K that is of the order of the sublimation temperature of interstellar dust grains. In the currently popular "puffed up rim" scenario, the bump represents stellar radiation that propagates through the optically thin inner region of the surrounding accretion disk and is absorbed and reemitted by the dust that resides just beyond the dust sublimation radius, Rsub. However, this model cannot account for the strongest bumps measured in these sources, and it predicts a large secondary bounce in the interferometric visibility curve that is not observed. In this paper we present an alternative interpretation, which attributes the bump to reemission of stellar radiation by dust that is u...

  4. Simulation Model of Membrane Gas Separator Using Aspen Custom Modeler

    Energy Technology Data Exchange (ETDEWEB)

    Song, Dong-keun [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of); Shin, Gahui; Yun, Jinwon; Yu, Sangseok [Chungnam Nat’l Univ., Daejeon (Korea, Republic of)

    2016-12-15

    Membranes are used to separate pure gas from gas mixtures. In this study, three different types of mass transport through a membrane were developed in order to investigate the gas separation capabilities of a membrane. The three different models typically used are a lumped model, a multi-cell model, and a discretization model. Despite the multi-cell model producing similar results to a discretization model, the discretization model was selected for this investigation, due to the cell number dependence of a multi-cell model. The mass transport model was then used to investigate the effects of pressure difference, flow rate, total exposed area, and permeability. The results showed that the pressure difference increased with the stage cut, but the selectivity was a trade-off for the increasing pressure difference. Additionally, even though permeability is an important parameter, the selectivity and stage cut of the membrane converged as permeability increased.

  5. Modeling Greenhouse Gas Emissions from Enteric Fermentation

    NARCIS (Netherlands)

    Kebreab, E.; Tedeschi, L.; Dijkstra, J.; Ellis, J.L.; Bannink, A.; France, J.

    2016-01-01

    Livestock directly contribute to greenhouse gas (GHG) emissions mainly through methane (CH4) and nitrous oxide (N2O) emissions. For cost and practicality reasons, quantification of GHG has been through development of various types of mathematical models. This chapter addresses the utility and limita

  6. Statistical Modeling Efforts for Headspace Gas

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Brian Phillip [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-17

    The purpose of this document is to describe the statistical modeling effort for gas concentrations in WIPP storage containers. The concentration (in ppm) of CO2 in the headspace volume of standard waste box (SWB) 68685 is shown. A Bayesian approach and an adaptive Metropolis-Hastings algorithm were used.

  7. Isotopic excesses of proton-rich nuclei related to space weathering observed in a gas-rich meteorite Kapoeta

    Energy Technology Data Exchange (ETDEWEB)

    Hidaka, Hiroshi [Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Yoneda, Shigekazu, E-mail: hidaka@hiroshima-u.ac.jp, E-mail: s-yoneda@kahaku.go.jp [Department of Science and Engineering, National Museum of Nature and Science, Tsukuba 305-0005 (Japan)

    2014-05-10

    The idea that solar system materials were irradiated by solar cosmic rays from the early Sun has long been suggested, but is still questionable. In this study, Sr, Ba, Ce, Nd, Sm, and Gd isotopic compositions of sequential acid leachates from the Kapoeta meteorite (howardite) were determined to find systematic and correlated variations in their isotopic abundances of proton-rich nuclei, leading to an understanding of the irradiation condition by cosmic rays. Significantly large excesses of proton-rich isotopes (p-isotopes), {sup 84}Sr, {sup 130}Ba, {sup 132}Ba, {sup 136}Ce, {sup 138}Ce, and {sup 144}Sm, were observed, particularly in the first chemical separate, which possibly leached out of the very shallow layer within a few μm from the surface of regolith grains in the sample. The results reveal the production of p-isotopes through the interaction of solar cosmic rays with the superficial region of the regolith grains before the formation of the Kapoeta meteorite parent body, suggesting strong activity in the early Sun.

  8. Evaluation of Turbulence Models in Gas Dispersion

    OpenAIRE

    Moen, Alexander

    2016-01-01

    Several earlier model validation studies for predicting gas dispersion scenarios have been conducted for the three RANS two-equation eddy viscosity turbulence models, the standard k-ε (SKE), Re- Normalisation group k-ε (RNG) and Realizable k-ε (Realizable). However, these studies have mainly validated one or two of the models, and have mostly used one simulation case as a basis for determining which model is the best suited for predicting such scenarios. In addition, the studies have shown co...

  9. The Excess of HERA High$-Q^2$ Events and Leptoquarks in a Left-Right Symmetric Preon Model

    CERN Document Server

    Sekiguchi, M; Ishida, S; Sekiguchi, Motoo; Wada, Hiroaki; Ishida, Shin

    1998-01-01

    An interpretation that the HERA excess events are due to intermediate production and decay of composite leptoquarks in the left-right symmetric preon model is given. Because of the preon-line rule, expected to be valid well, the event-ratio of neutral to charged current interactions is predicted to be one.

  10. The Excess of HERA High-Q2 Events and Leptoquarks in a Left-Right Symmetric Preon Model

    Science.gov (United States)

    Sekiguchi, M.; Wada, H.; Ishida, S.

    1998-04-01

    An interpretation that the HERA excess events are due to intermediate production and decay of composite leptoquarks in the left-right symmetric preon model is given. Because of the preon-line rule, expected to be valid, the event-ratio of neutral to charged current interactions is predicted to be 1.

  11. Individual Diet Modeling Shows How to Balance the Diet of French Adults with or without Excessive Free Sugar Intakes.

    Science.gov (United States)

    Lluch, Anne; Maillot, Matthieu; Gazan, Rozenn; Vieux, Florent; Delaere, Fabien; Vaudaine, Sarah; Darmon, Nicole

    2017-02-20

    Dietary changes needed to achieve nutritional adequacy for 33 nutrients were determined for 1719 adults from a representative French national dietary survey. For each individual, an iso-energy nutritionally adequate diet was generated using diet modeling, staying as close as possible to the observed diet. The French food composition table was completed with free sugar (FS) content. Results were analyzed separately for individuals with FS intakes in their observed diets ≤10% or >10% of their energy intake (named below FS-ACCEPTABLE and FS-EXCESS, respectively). The FS-EXCESS group represented 41% of the total population (average energy intake of 14.2% from FS). Compared with FS-ACCEPTABLE individuals, FS-EXCESS individuals had diets of lower nutritional quality and consumed more energy (2192 vs. 2123 kcal/day), particularly during snacking occasions (258 vs. 131 kcal/day) (all p-values fresh fruits, starchy foods, water, hot beverages and plain yogurts; and significant decreases in mixed dishes/sandwiches, meat/eggs/fish and cheese. For FS-EXCESS individuals only, the optimization process significantly increased vegetables and significantly decreased sugar-sweetened beverages, sweet products and fruit juices. The diets of French adults with excessive intakes of FS are of lower nutritional quality, but can be optimized via specific dietary changes.

  12. Individual Diet Modeling Shows How to Balance the Diet of French Adults with or without Excessive Free Sugar Intakes

    Science.gov (United States)

    Lluch, Anne; Maillot, Matthieu; Gazan, Rozenn; Vieux, Florent; Delaere, Fabien; Vaudaine, Sarah; Darmon, Nicole

    2017-01-01

    Dietary changes needed to achieve nutritional adequacy for 33 nutrients were determined for 1719 adults from a representative French national dietary survey. For each individual, an iso-energy nutritionally adequate diet was generated using diet modeling, staying as close as possible to the observed diet. The French food composition table was completed with free sugar (FS) content. Results were analyzed separately for individuals with FS intakes in their observed diets ≤10% or >10% of their energy intake (named below FS-ACCEPTABLE and FS-EXCESS, respectively). The FS-EXCESS group represented 41% of the total population (average energy intake of 14.2% from FS). Compared with FS-ACCEPTABLE individuals, FS-EXCESS individuals had diets of lower nutritional quality and consumed more energy (2192 vs. 2123 kcal/day), particularly during snacking occasions (258 vs. 131 kcal/day) (all p-values cheese. For FS-EXCESS individuals only, the optimization process significantly increased vegetables and significantly decreased sugar-sweetened beverages, sweet products and fruit juices. The diets of French adults with excessive intakes of FS are of lower nutritional quality, but can be optimized via specific dietary changes. PMID:28230722

  13. Time-Lagging Interplay Effect and Excess Risk of Meteorological/Mosquito Parameters and Petrochemical Gas Explosion on Dengue Incidence

    Science.gov (United States)

    Chang, Ko; Chen, Chaur-Dong; Shih, Chien-Ming; Lee, Tzu-Chi; Wu, Ming-Tsang; Wu, Deng-Chyang; Chen, Yen-Hsu; Hung, Chih-Hsing; Wu, Meng-Chieh; Huang, Chun-Chi; Lee, Chien-Hung; Ho, Chi-Kung

    2016-01-01

    In Kaohsiung, a metropolitan city in Taiwan at high risk of dengue epidemic, weather factors combined with an accidental petrochemical gas explosion (PGE) may affect mosquito‒human dynamics in 2014. Generalized estimating equations with lagged-time Poisson regression analyses were used to evaluate the effect of meteorological/mosquito parameters and PGE on dengue incidences (2000–2014) in Kaohsiung. Increased minimum temperatures rendered a 2- and 3-month lagging interactive effect on higher dengue risks, and higher rainfall exhibited a 1- and 2-month lagging interplay effect on lower risks (interaction, P ≤ 0.001). The dengue risk was significantly higher than that in a large-scale outbreak year (2002) from week 5 after PGE accident in 2014 (2.9‒8.3-fold for weeks 5‒22). The greatest cross-correlation of dengue incidences in the PGE-affected and PGE-neighboring districts was identified at weeks 1 after the PGE (rs = 0.956, P mosquito‒human dynamics, such as PGEs, should not be ignored in dengue prevention and control. PMID:27733774

  14. 75 FR 53371 - Liquefied Natural Gas Facilities: Obtaining Approval of Alternative Vapor-Gas Dispersion Models

    Science.gov (United States)

    2010-08-31

    ... of Alternative Vapor-Gas Dispersion Models AGENCY: Pipeline and Hazardous Materials Safety... provides guidance on the requirements for obtaining approval of alternative vapor-gas dispersion models... vapor-gas dispersion. Certain mathematical models and other parameters must be used to calculate the...

  15. Exclusion of measurements with excessive residuals (blunders) in estimating model parameters

    CERN Document Server

    Nikiforov, I I

    2013-01-01

    An adjustable algorithm of exclusion of conditional equations with excessive residuals is proposed. The criteria applied in the algorithm use variable exclusion limits which decrease as the number of equations goes down. The algorithm is easy to use, it possesses rapid convergence, minimal subjectivity, and high degree of generality.

  16. Multisite Interactions in Lattice-Gas Models

    Science.gov (United States)

    Einstein, T. L.; Sathiyanarayanan, R.

    For detailed applications of lattice-gas models to surface systems, multisite interactions often play at least as significant a role as interactions between pairs of adatoms that are separated by a few lattice spacings. We recall that trio (3-adatom, non-pairwise) interactions do not inevitably create phase boundary asymmetries about half coverage. We discuss a sophisticated application to an experimental system and describe refinements in extracting lattice-gas energies from calculations of total energies of several different ordered overlayers. We describe how lateral relaxations complicate matters when there is direct interaction between the adatoms, an issue that is important when examining the angular dependence of step line tensions. We discuss the connector model as an alternative viewpoint and close with a brief account of recent work on organic molecule overlayers.

  17. Influence of model grid size on the simulation of PM2.5 and the related excess mortality in Japan

    Science.gov (United States)

    Goto, D.; Ueda, K.; Ng, C. F.; Takami, A.; Ariga, T.; Matsuhashi, K.; Nakajima, T.

    2016-12-01

    Aerosols, especially PM2.5, can affect air pollution, climate change, and human health. The estimation of health impacts due to PM2.5 is often performed using global and regional aerosol transport models with various horizontal resolutions. To investigate the dependence of the simulated PM2.5 on model grid sizes, we executed two simulations using a high-resolution model ( 10km; HRM) and a low-resolution model ( 100km; LRM, which is a typical value for general circulation models). In this study, we used a global-to-regional atmospheric transport model to simulate PM2.5 in Japan with a stretched grid system in HRM and a uniform grid system in LRM for the present (the 2000) and the future (the 2030, as proposed by the Representative Concentrations Pathway 4.5, RCP4.5). These calculations were performed by nudging meteorological fields obtained from an atmosphere-ocean coupled model and providing emission inventories used in the coupled model. After correcting for bias, we calculated the excess mortality due to long-term exposure to PM2.5 for the elderly. Results showed the LRM underestimated by approximately 30 % (of PM2.5 concentrations in the 2000 and 2030), approximately 60 % (excess mortality in the 2000) and approximately 90 % (excess mortality in 2030) compared to the HRM results. The estimation of excess mortality therefore performed better with high-resolution grid sizes. In addition, we also found that our nesting method could be a useful tool to obtain better estimation results.

  18. Interacting holographic generalized cosmic Chaplygin gas model

    Science.gov (United States)

    Naji, Jalil

    2014-03-01

    In this paper we consider a correspondence between the holographic dark energy density and interacting generalized cosmic Chaplygin gas energy density in flat FRW universe. Then, we reconstruct the potential of the scalar field which describe the generalized cosmic Chaplygin cosmology. In the special case we obtain time-dependent energy density and study cosmological parameters. We find stability condition of this model which is depend on cosmic parameter.

  19. Enhancing Resilience to Heat Extremes: Multi-model Forecasting of Excessive Heat Events at Subseasonal Lead Times

    Science.gov (United States)

    Vintzileos, A.; Halpert, M.; Gottschalk, J.; Allgood, A.

    2016-12-01

    Heatwaves are among the most dangerous, yet invisible, of natural hazards. According to NOAA, the distribution of 30-year based annual mean fatalities from natural hazards in the U.S. ranks as follows; those from heat (130), floods (81), tornadoes (70), lightning (48) and hurricanes (46). Early warning to excessive heat events can be improved by using multi-scale prognostic systems. We designed and developed such a system for forecasting excessive heat events at lead times beyond Week-1. This Subseasonal Excessive Heat Outlook System (SEHOS) consists of (a) a monitoring/verification component and (b) a forecasting component which in its baseline version uses NOAA's Global Ensemble Forecast System (GEFS) predictions of temperature and humidity from Day-8 to Day-14. In this presentation, we discuss the definition of heat events, sources of predictability and present the forecast skill of SEHOS for the GEFS reforecast period (1985-2014). We then use subseasonal reforecasts from several models from the S2S database and discuss the forecast value added by multi-model approaches in predicting excessive heat events.

  20. Modelling and Simulation of Gas Engines Using Aspen HYSYS

    OpenAIRE

    M. C. Ekwonu; Perry, S.; E. A. Oyedoh

    2013-01-01

    In this paper gas engine model was developed in Aspen HYSYS V7.3 and validated with Waukesha 16V275GL+ gas engine. Fuel flexibility, fuel types and part load performance of the gas engine were investigated. The design variability revealed that the gas engine can operate on poor fuel with low lower heating value (LHV) such as landfill gas, sewage gas and biogas with biogas offering potential integration with bottoming cycles when compared to natural gas. The result of the gas engin...

  1. Modelling and Simulation of Gas Engines Using Aspen HYSYS

    OpenAIRE

    M. C. Ekwonu; Perry, S.; E. A. Oyedoh

    2013-01-01

    In this paper gas engine model was developed in Aspen HYSYS V7.3 and validated with Waukesha 16V275GL+ gas engine. Fuel flexibility, fuel types and part load performance of the gas engine were investigated. The design variability revealed that the gas engine can operate on poor fuel with low lower heating value (LHV) such as landfill gas, sewage gas and biogas with biogas offering potential integration with bottoming cycles when compared to natural gas. The result of the gas engin...

  2. Modelling and Simulation of Gas Engines Using Aspen HYSYS

    Directory of Open Access Journals (Sweden)

    M. C. Ekwonu

    2013-12-01

    Full Text Available In this paper gas engine model was developed in Aspen HYSYS V7.3 and validated with Waukesha 16V275GL+ gas engine. Fuel flexibility, fuel types and part load performance of the gas engine were investigated. The design variability revealed that the gas engine can operate on poor fuel with low lower heating value (LHV such as landfill gas, sewage gas and biogas with biogas offering potential integration with bottoming cycles when compared to natural gas. The result of the gas engine simulation gave an efficiency 40.7% and power output of 3592kW.

  3. Mathematical analysis of intermittent gas injection model in oil production

    Science.gov (United States)

    Tasmi, Silvya, D. R.; Pudjo, S.; Leksono, M.; Edy, S.

    2016-02-01

    Intermittent gas injection is a method to help oil production process. Gas is injected through choke in surface and then gas into tubing. Gas forms three areas in tubing: gas column area, film area and slug area. Gas column is used to propel slug area until surface. A mathematical model of intermittent gas injection is developed in gas column area, film area and slug area. Model is expanding based on mass and momentum conservation. Using assume film thickness constant in tubing, model has been developed by Tasmi et. al. [14]. Model consists of 10 ordinary differential equations. In this paper, assumption of pressure in gas column is uniform. Model consist of 9 ordinary differential equations. Connection of several variables can be obtained from this model. Therefore, dynamics of all variables that affect to intermittent gas lift process can be seen from four equations. To study the behavior of variables can be analyzed numerically and mathematically. In this paper, simple mathematically analysis approach is used to study behavior of the variables. Variables that affect to intermittent gas injection are pressure in upstream valve and in gas column. Pressure in upstream valve will decrease when gas mass in valve greater than gas mass in choke. Dynamic of the pressure in the gas column will decrease and increase depending on pressure in upstream valve.

  4. Excess molar enthalpies and excess molar volumes of formamide + 1-propanol or 2-propanol and thermodynamic modeling by Prigogine–Flory–Patterson theory and Treszczanowicz–Benson association model

    Energy Technology Data Exchange (ETDEWEB)

    Rani, Manju [Department of Chemical Engineering, Deenbandhu Chhotu Ram University of Science and Technology, Murthal 131 039 (India); Maken, Sanjeev, E-mail: sanjeevmakin@gmail.com [Department of Chemistry, Deenbandhu Chhotu Ram University of Science and Technology, Murthal 131 039 (India)

    2013-05-10

    Highlights: ► Measured H{sub m}{sup E} and V{sub m}{sup E} data of formamide + propanol were interpreted in terms of PFP theory. ► Treszczanowicz–Benson association model was also applied to these binary systems. ► The calculated H{sub m}{sup E} and V{sub m}{sup E} values compared well with corresponding experimental data. ► Extent of H-bonding in formamide and propanol in their mixture was reflected in Δh{sub H}{sup 0} and K{sub H}. - Abstract: Excess molar enthalpies (H{sub m}{sup E}) at 298.15 K and 308.15 K and excess molar volumes (V{sub m}{sup E}) at 308.15 K for formamide (1) + 1-propanol or 2-propanol (2) mixtures have been measured over the entire composition range. The excess enthalpies and excess volumes data have been utilized to study the thermodynamics of molecular interactions in terms of Prigogine–Flory–Patterson theory and Treszczanowicz–Benson association model with a Flory contribution term. In this paper, this Treszczanowicz–Benson association model was applied, for the first time, to binary mixtures containing both components associated (propanol and formamide) through hydrogen bonding. In both the cases, when either of formamide or propanol was assumed to be associated, the calculated H{sub m}{sup E} and V{sub m}{sup E} values compared well with corresponding experimental data. Extent of inter-molecular H-bonding in formamide and propanol in their binary mixtures was also reflected in their molar enthalpy of association of H-bonding Δh{sub H}{sup 0} and association constant K{sub H}.

  5. Study of phase separation using liquid-gas model of lattice-gas cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Ebihara, Kenichi; Watanabe, Tadashi; Kaburaki, Hideo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-07-01

    This report describes the study of phase separation by the liquid gas model of lattice gas cellular automata. The lattice gas cellular automaton is one model for simulating fluid phenomena which was proposed by Frisch, Hasslacher and Pomeau in 1986. In 1990, Appert and Zaleski added a new long-range interaction to lattice gas cellular automata to construct a model, the liquid-gas model, which could simulate phase separation using lattice-gas cellular automata. Gerits et al formulated the liquid-gas model mathematically using the theory of statistical dynamics in 1993 and explained the mechanism of phase separation in the liquid-gas model using the equation of state. At first this report explains the FHP model of lattice gas cellular automata and derives fluid dynamics equations such as the equation of continuity and the Navier-Stokes equation. Then the equation of state for the liquid-gas model which was derived by Gerits et al is modified by adding the interactions which were proposed by Appert but not considered by Gerits et al. The modified equation of state is verified by the computer simulation using the liquid gas model. The relation between phase separation and the equation of state is discussed. (author)

  6. Interpreting the 750 GeV diphoton excess by the singlet extension of the Manohar-Wise model

    Science.gov (United States)

    Cao, Junjie; Han, Chengcheng; Shang, Liangliang; Su, Wei; Yang, Jin Min; Zhang, Yang

    2016-04-01

    The evidence of a new scalar particle X from the 750 GeV diphoton excess, and the absence of any other signal of new physics at the LHC so far suggest the existence of new colored scalars, which may be moderately light and thus can induce sizable Xgg and Xγγ couplings without resorting to very strong interactions. Motivated by this speculation, we extend the Manohar-Wise model by adding one gauge singlet scalar field. The resulting theory then predicts one singlet dominated scalar ϕ as well as three kinds of color-octet scalars, which can mediate through loops the ϕgg and ϕγγ interactions. After fitting the model to the diphoton data at the LHC, we find that in reasonable parameter regions the excess can be explained at 1σ level by the process gg → ϕ → γγ, and the best points predict the central value of the excess rate with χmin2 = 2.32, which corresponds to a p-value of 0.68. We also consider the constraints from various LHC Run I signals, and we conclude that, although these constraints are powerful in excluding the parameter space of the model, the best points are still experimentally allowed.

  7. Mathematical model of diffusion-limited evolution of multiple gas bubbles in tissue.

    Science.gov (United States)

    Srinivasan, R Srini; Gerth, Wayne A; Powell, Michael R

    2003-04-01

    Models of gas bubble dynamics employed in probabilistic analyses of decompression sickness incidence in man must be theoretically consistent and simple, if they are to yield useful results without requiring excessive computations. They are generally formulated in terms of ordinary differential equations that describe diffusion-limited gas exchange between a gas bubble and the extravascular tissue surrounding it. In our previous model (Ann. Biomed. Eng. 30: 232-246, 2002), we showed that with appropriate representation of sink pressures to account for gas loss or gain due to heterogeneous blood perfusion in the unstirred diffusion region around the bubble, diffusion-limited bubble growth in a tissue of finite volume can be simulated without postulating a boundary layer across which gas flux is discontinuous. However, interactions between two or more bubbles caused by competition for available gas cannot be considered in this model, because the diffusion region has a fixed volume with zero gas flux at its outer boundary. The present work extends the previous model to accommodate interactions among multiple bubbles by allowing the diffusion region volume of each bubble to vary during bubble evolution. For given decompression and tissue volume, bubble growth is sustained only if the bubble number density is below a certain maximum.

  8. Excessive Cold-tongue and Weak ENSO Asymmetry: Are These Two Common Biases in Climate Models Linked?

    Science.gov (United States)

    Sun, D. Z.

    2014-12-01

    Among the biases in the tropical Pacific that are common in the climate models, two stand out. One is the excessive cold-tongue in the mean state---the pool of the cold water that is normally in the eastern tropical Pacific extends too far to the west. The other is the underestimate of the asymmetry of El Nino-Southern Oscillation—the fact that El Nino and La Nina are more or less a mirror image of each other in the models while they are not so in the observations. Results from an analysis from CMIP5 models, forced ocean GCM experiments, as well as an analytical model are presented to suggest that these two common biases in our state-of-the-art models are linked. Specifically, an excessive cold-tongue in the mean climatological state makes the ENSO system more stable and thus leads to a more symmetric ENSO, while a more symmetric ENSO in turn results in less nonlinear heating from the ENSO events to the cental equatorial Pacific which in turn contributes to the development of an excessive cold-tongue. The finding underscores that errors in the mean state and ENSO tend to reinforce each other and thus explains why it has been difficult to simulate the tropical Pacific climate. Further comparison with observations suggests that these two biases are the symptoms of a single structural inadequacy in the models: a weak dynamical coupling between the atmosphere and ocean which puts the ENSO system in the models to a different dynamic regime than the obsereved. Measures that may help push the models closer to the observations are suggested.

  9. Retention models for programmed gas chromatography.

    Science.gov (United States)

    Castello, G; Moretti, P; Vezzani, S

    2009-03-06

    The models proposed by many authors for the prediction of retention times and temperatures, peak widths, retention indices and separation numbers in programmed temperature and pressure gas chromatography by starting from preliminary measurements of the retention in isothermal and isobaric conditions are reviewed. Several articles showing the correlation between retention data and thermodynamic parameters and the determination of the optimum programming rate are reported. The columns of different polarity used for the experimental measurement and the main equations, mathematical models and calculation procedures are listed. An empirical approach was used in the early models, followed by the application of thermodynamic considerations, iterative calculation procedures and statistical methods, based on increased computing power now available. Multiple column arrangements, simultaneous temperature and pressure programming, applications of two-dimensional and fast chromatography are summarised.

  10. Modelling the Molecular Gas in NGC 6240

    CERN Document Server

    Tunnard, R; Garcia-Burillo, S; Carpio, J Graciá; Fuente, A; Tacconi, L; Neri, R; Usero, A

    2015-01-01

    We present the first observations of H$^{13}$CN$(1-0)$, H$^{13}$CO$^+(1-0)$ and SiO$(2-1)$ in NGC 6240, obtained with the IRAM PdBI. Combining a Markov Chain Monte Carlo (MCMC) code with Large Velocity Gradient (LVG) modelling we derive posterior probability density functions (pdfs) for the dense gas parameters, including mass$-$luminosity conversion factors, finding a large amount of dense molecular gas $(\\sim10^{10}M_\\odot)$ in cold, dense clouds ($T_k\\sim10$ K, $n_{{\\rm H}_2}\\sim10^6$ cm$^{-3}$) with a small volume filling factor $(<0.002)$. Including literature CO data we present simultaneously fitted multi-species, two phase models which spontaneously separate into a hot, diffuse phase ($\\log_{10}\\left(T_k / [{\\rm K}]\\right) = 3.2^{3.3}_{3.1}$, $\\log_{10}\\left(n_{{\\rm H}_2} / [{\\rm cm}^{-3}]\\right)=3.6^{3.8}_{3.5}$) and a cold, dense phase ($\\log_{10}\\left(T_k / [{\\rm K}]\\right) = 0.9^{0.9}_{0.8}$, $\\log_{10}\\left(n_{{\\rm H}_2} / [{\\rm cm}^{-3}]\\right)=6.6^{6.8}_{6.3}$). A restricted three phase model...

  11. A computationally identified compound antagonizes excess FGF-23 signaling in renal tubules and a mouse model of hypophosphatemia.

    Science.gov (United States)

    Xiao, Zhousheng; Riccardi, Demian; Velazquez, Hector A; Chin, Ai L; Yates, Charles R; Carrick, Jesse D; Smith, Jeremy C; Baudry, Jerome; Quarles, L Darryl

    2016-11-22

    Fibroblast growth factor-23 (FGF-23) interacts with a binary receptor complex composed of α-Klotho (α-KL) and FGF receptors (FGFRs) to regulate phosphate and vitamin D metabolism in the kidney. Excess FGF-23 production, which causes hypophosphatemia, is genetically inherited or occurs with chronic kidney disease. Among other symptoms, hypophosphatemia causes vitamin D deficiency and the bone-softening disorder rickets. Current therapeutics that target the receptor complex have limited utility clinically. Using a computationally driven, structure-based, ensemble docking and virtual high-throughput screening approach, we identified four novel compounds predicted to selectively inhibit FGF-23-induced activation of the FGFR/α-KL complex. Additional modeling and functional analysis found that Zinc13407541 bound to FGF-23 and disrupted its interaction with the FGFR1/α-KL complex; experiments in a heterologous cell expression system showed that Zinc13407541 selectivity inhibited α-KL-dependent FGF-23 signaling. Zinc13407541 also inhibited FGF-23 signaling in isolated renal tubules ex vivo and partially reversed the hypophosphatemic effects of excess FGF-23 in a mouse model. These chemical probes provide a platform to develop lead compounds to treat disorders caused by excess FGF-23.

  12. On-Shell Mediators and Top-Charm Dark Matter Models for the Fermi-LAT Galactic Center Excess

    CERN Document Server

    Rajaraman, Arvind; Tanedo, Philip

    2015-01-01

    An excess in gamma-rays from the galactic center observed by the Fermi Large Area Telescope has been proposed as a possible signal of dark matter annihilation. Recently, the Fermi collaboration showed that systematic errors broaden the range of spectral shapes for this excess. We demonstrate fits to this range for (1) flavor-violating annihilations to top-charm pairs and (2) annihilations to on-shell bosonic mediators which decay to Standard Model quarks in a boosted frame. Annihilation of 40 - 100 GeV DM to pairs of spin-1 mediators provide a good fit to the Fermi-LAT spectrum with a normalization consistent with a thermal relic. Top-charm modes and annihilation to three pseudoscalar mediators can fit the spectral shape but typically require non-thermal annihilation cross sections.

  13. Modelling of gas flow through metallic foams

    Energy Technology Data Exchange (ETDEWEB)

    Crosnier, S. [CEA Grenoble, Dept. de Thermohydraulique et de Physique, 38 (France); Riva, R. [CEA Cadarache, 13 - Saint Paul lez Durance (France); Bador, B.; Blet, V.

    2003-09-01

    The transport and distribution of gases (hydrogen at the anode and air at the cathode) and water over the front surfaces of the electrodes in contact with electrolyte membrane are of great importance for the enhancement of efficiency of the Proton Exchange Membrane Fuel Cells (PEMFC). The use of metallic foam as a flow distributor in comparison with grooved plate (formed by parallel channels) commonly used in commercial fuel cells may be advantageous since this porous material has a porosity close to unity and then high specific surface area. In fact, the potentially active surface area is generally considered to be almost equal to the front surface area of the electrodes. In order to ensure a homogeneous flow distribution all over the active surface of such devices, a good understanding of gas flow through these particular porous media is necessary. For that purpose, studying of two-phase flow (oxygen, hydrogen and water) through metallic foams must be undertaken. This is carried out in the present work but, in a first step, only for single-phase flow, since the behaviour of two-phase flow derives from the first one. Novels hydraulic models have then been developed in the literature these last years. However, these models do not take into account the viscous dissipation of the flow along the walls bordering the porous media. Unfortunately, metallic foam used as distributors in fuel cell have thigh thickness (of the order of the millimeter), that shedding a doubt on the validity of the latter assumption. In this paper, we review the different hydraulic models in order to discuss the relevance and the limits of each to describe single-phase flow through foams which could be used as distributor in a fuel cell. For that purpose, numerical solutions obtained using modified MC3D-REPO package originally developed for the modelling of multicomponent two-phase flows in granular porous media have been compared to experimental data measured on a dedicated hydraulic device

  14. Amplification of enantiomeric excess, mirror-image symmetry breaking and kinetic proofreading in Soai reaction models with different oligomeric orders.

    Science.gov (United States)

    Micheau, Jean-Claude; Coudret, Christophe; Cruz, José-Manuel; Buhse, Thomas

    2012-10-14

    A comprehensive kinetic analysis of three prototypical autocatalytic cycle models based on the absolute asymmetric Soai reaction is presented. The three models, which can give rise to amplification of enantiomeric excess and mirror-image symmetry breaking, vary by their monomeric, dimeric or trimeric order of the assumed catalytic species. Our numerical approach considered the entire chiral combinatorics of the diastereomeric interactions in the models as well as the multiplicity of coupled reversible reactions without applying fast equilibration or quasi-steady state approximations. For the simplest monomeric model, an extensive range of parameters was explored employing a random grid parameter scanning method that revealed the influence of the parameter values on the product distribution, the reaction-time, the attenuation or amplification of enantiomeric excess as well as on the presence or absence of mirror-image symmetry breaking. A symmetry breaking test was imposed on the three models showing that an increase in the catalytic oligomer size from one to three leads to a higher tolerance to poorer chiral recognition between the diastereoisomers and identifies the greater impact of the diastereoisomeric energy difference over an imperfect stereoselectivity in the catalytic step. This robustness is understood as a particular case of so-called kinetic proofreading in asymmetric autocatalysis.

  15. Scenario analysis of gas crisis using the European Gas Assessment Model (EUGas)

    OpenAIRE

    RODRIGUEZ GOMEZ NURIA; ZACCARELLI NICOLA; PAMBOUR KWABENA; BOLADO LAVIN Ricardo

    2014-01-01

    The European Gas Assessment model (EUGas) is a country level model of the European gas transmission pipeline network which is being developed by JRC-IET (Joint Research Centre – Institute for Energy and Transport). The model aims at supporting Directive 2008/114/EC on “the identification and designation of European Critical Infrastructure (ECI)” and Regulation 994/2010 on “measures to safeguard security of gas supply”. The hydraulic model of the European gas network is developed using a combi...

  16. Evaluation of the gas production economics of the gas hydrate cyclic thermal injection model

    Energy Technology Data Exchange (ETDEWEB)

    Kuuskraa, V.A.; Hammersheimb, E.; Sawyer, W.

    1985-05-01

    The objective of the work performed under this directive is to assess whether gas hydrates could potentially be technically and economically recoverable. The technical potential and economics of recovering gas from a representative hydrate reservoir will be established using the cyclic thermal injection model, HYDMOD, appropriately modified for this effort, integrated with economics model for gas production on the North Slope of Alaska, and in the deep offshore Atlantic. The results from this effort are presented in this document. In Section 1, the engineering cost and financial analysis model used in performing the economic analysis of gas production from hydrates -- the Hydrates Gas Economics Model (HGEM) -- is described. Section 2 contains a users guide for HGEM. In Section 3, a preliminary economic assessment of the gas production economics of the gas hydrate cyclic thermal injection model is presented. Section 4 contains a summary critique of existing hydrate gas recovery models. Finally, Section 5 summarizes the model modification made to HYDMOD, the cyclic thermal injection model for hydrate gas recovery, in order to perform this analysis.

  17. Lung cancer mortality (1950-1999 among Eldorado uranium workers: a comparison of models of carcinogenesis and empirical excess risk models.

    Directory of Open Access Journals (Sweden)

    Markus Eidemüller

    Full Text Available Lung cancer mortality after exposure to radon decay products (RDP among 16,236 male Eldorado uranium workers was analyzed. Male workers from the Beaverlodge and Port Radium uranium mines and the Port Hope radium and uranium refinery and processing facility who were first employed between 1932 and 1980 were followed up from 1950 to 1999. A total of 618 lung cancer deaths were observed. The analysis compared the results of the biologically-based two-stage clonal expansion (TSCE model to the empirical excess risk model. The spontaneous clonal expansion rate of pre-malignant cells was reduced at older ages under the assumptions of the TSCE model. Exposure to RDP was associated with increase in the clonal expansion rate during exposure but not afterwards. The increase was stronger for lower exposure rates. A radiation-induced bystander effect could be a possible explanation for such an exposure response. Results on excess risks were compared to a linear dose-response parametric excess risk model with attained age, time since exposure and dose rate as effect modifiers. In all models the excess relative risk decreased with increasing attained age, increasing time since exposure and increasing exposure rate. Large model uncertainties were found in particular for small exposure rates.

  18. Diphoton Excess at 750 GeV in leptophobic U(1)$^\\prime$ model inspired by $E_6$ GUT

    CERN Document Server

    Ko, P; Yu, Chaehyun

    2016-01-01

    We discuss the 750 GeV diphoton excess at the LHC@13TeV in the framework of leptophobic U(1)$^\\prime$ model inspired by the $E_6$ grand unified theory (GUT). In this model, the Standard Model (SM) chiral fermions carry charges under extra U(1)$^\\prime$ gauge symmetry which is spontaneously broken by a U(1)$^\\prime$-charged singlet scalar ($\\Phi$). In addition, extra quarks and leptons are introduced to achieve the anomaly-free conditions, which is a natural consequence of the assumed $E_6$ GUT. These new fermions are vectorlike under the SM gauge group but chiral under new U(1)$^\\prime$, and their masses come entirely from the nonzero vacuum expectation value of $\\Phi$ through the Yukawa interactions. Then, the CP-even scalar $h_\\Phi$ from $\\Phi$ can be produced at the LHC by the gluon fusion and decay to the diphoton via the one-loop diagram involving the extra quarks and leptons, and can be identified as the origin of diphoton excess at 750 GeV. In this model, $h_\\Phi$ can decay into a pair of dark matter p...

  19. Renormalizable model for neutrino mass, dark matter, muon g−2 and 750 GeV diphoton excess

    Directory of Open Access Journals (Sweden)

    Hiroshi Okada

    2016-05-01

    Full Text Available We discuss a possibility to explain the 750 GeV diphoton excess observed at the LHC in a three-loop neutrino mass model which has a similar structure to the model by Krauss, Nasri and Trodden. Tiny neutrino masses are naturally generated by the loop effect of new particles with their couplings and masses to be of order 0.1–1 and TeV, respectively. The lightest right-handed neutrino, which runs in the three-loop diagram, can be a dark matter candidate. In addition, the deviation in the measured value of the muon anomalous magnetic moment from its prediction in the standard model can be compensated by one-loop diagrams with exotic multi-charged leptons and scalar bosons. For the diphoton event, an additional isospin singlet real scalar field plays the role to explain the excess by taking its mass of 750 GeV, where it is produced from the gluon fusion production via the mixing with the standard model like Higgs boson. We find that the cross section of the diphoton process can be obtained to be a few fb level by taking the masses of new charged particles to be about 375 GeV and related coupling constants to be order 1.

  20. Explaining the CMS excesses, baryogenesis, and neutrino masses in a E6 motivated U (1 )N model

    Science.gov (United States)

    Dhuria, Mansi; Hati, Chandan; Sarkar, Utpal

    2016-01-01

    We study the superstring inspired E6 model motivated U (1 )N extension of the supersymmetric standard model to explore the possibility of explaining the recent excess CMS events and the baryon asymmetry of the Universe in eight possible variants of the model. In light of the hints from short-baseline neutrino experiments at the existence of one or more light sterile neutrinos, we also study the neutrino mass matrices dictated by the field assignments and the discrete symmetries in these variants. We find that all the variants can explain the excess CMS events via the exotic slepton decay, while for a standard choice of the discrete symmetry four of the variants have the feature of allowing high scale baryogenesis (leptogenesis). For one other variant three body decay induced soft baryogenesis mechanism is possible which can induce baryon number violating neutron-antineutron oscillation. We also point out a new discrete symmetry which has the feature of ensuring proton stability and forbidding tree level flavor changing neutral current processes while allowing for the possibility of high scale leptogenesis for two of the variants. On the other hand, neutrino mass matrix of the U (1 )N model variants naturally accommodates three active and two sterile neutrinos which acquire masses through their mixing with extra neutral fermions giving rise to interesting textures for neutrino masses.

  1. Excessive folate synthesis limits lifespan in the C. elegans: E. coli aging model

    Directory of Open Access Journals (Sweden)

    Virk Bhupinder

    2012-07-01

    Full Text Available Abstract Background Gut microbes influence animal health and thus, are potential targets for interventions that slow aging. Live E. coli provides the nematode worm Caenorhabditis elegans with vital micronutrients, such as folates that cannot be synthesized by animals. However, the microbe also limits C. elegans lifespan. Understanding these interactions may shed light on how intestinal microbes influence mammalian aging. Results Serendipitously, we isolated an E. coli mutant that slows C. elegans aging. We identified the disrupted gene to be aroD, which is required to synthesize aromatic compounds in the microbe. Adding back aromatic compounds to the media revealed that the increased C. elegans lifespan was caused by decreased availability of para-aminobenzoic acid, a precursor to folate. Consistent with this result, inhibition of folate synthesis by sulfamethoxazole, a sulfonamide, led to a dose-dependent increase in C. elegans lifespan. As expected, these treatments caused a decrease in bacterial and worm folate levels, as measured by mass spectrometry of intact folates. The folate cycle is essential for cellular biosynthesis. However, bacterial proliferation and C. elegans growth and reproduction were unaffected under the conditions that increased lifespan. Conclusions In this animal:microbe system, folates are in excess of that required for biosynthesis. This study suggests that microbial folate synthesis is a pharmacologically accessible target to slow animal aging without detrimental effects.

  2. Modelling emissions from natural gas flaring

    OpenAIRE

    G. Ezaina Umukoro; O. Saheed Ismail

    2017-01-01

    The world today recognizes the significance of environmental sustainability to the development of nations. Hence, the role oil and gas industry plays in environmental degrading activities such as gas flaring is of global concern. This study presents material balance equations and predicts results for non-hydrocarbon emissions such as CO2, CO, NO, NO2, and SO2 etc. from flaring (combustion) of 12 natural gas samples representing composition of natural gas of global origin. Gaseous emission est...

  3. Coordinated scheduling of electricity and natural gas infrastructures with a transient model for natural gas flow.

    Science.gov (United States)

    Liu, Cong; Shahidehpour, Mohammad; Wang, Jianhui

    2011-06-01

    This paper focuses on transient characteristics of natural gas flow in the coordinated scheduling of security-constrained electricity and natural gas infrastructures. The paper takes into account the slow transient process in the natural gas transmission systems. Considering their transient characteristics, natural gas transmission systems are modeled as a set of partial differential equations (PDEs) and algebraic equations. An implicit finite difference method is applied to approximate PDEs by difference equations. The coordinated scheduling of electricity and natural gas systems is described as a bi-level programming formulation from the independent system operator's viewpoint. The objective of the upper-level problem is to minimize the operating cost of electric power systems while the natural gas scheduling optimization problem is nested within the lower-level problem. Numerical examples are presented to verify the effectiveness of the proposed solution and to compare the solutions for steady-state and transient models of natural gas transmission systems.

  4. The 750 GeV diphoton excess in unified Pati-Salam models from noncommutative geometry

    CERN Document Server

    Aydemir, Ufuk; Sun, Chen; Takeuchi, Tatsu

    2016-01-01

    We discuss a possible interpretation of the $750$ GeV diphoton resonance, recently reported at the LHC, within a class of Pati-Salam models with gauge coupling unification. The unification is imposed by the underlying non-commutative geometry (NCG), which in these models is extended to a left-right symmetric completion of the Standard Model (SM). Within such unified Pati-Salam models the Higgs content is restrictively determined from the underlying NCG, instead of being arbitrarily selected as in canonical, non-unified, Pati-Salam models. We show that the observed cross sections involving the $750$ GeV diphoton resonance could be realized through a SM singlet scalar field accompanied by colored scalars, present in these unified models. In view of this result we discuss the underlying rigidity of these models in the NCG framework and the wider implications of the NCG approach for physics beyond the SM.

  5. Gas explosion prediction using CFD models

    Energy Technology Data Exchange (ETDEWEB)

    Niemann-Delius, C.; Okafor, E. [RWTH Aachen Univ. (Germany); Buhrow, C. [TU Bergakademie Freiberg Univ. (Germany)

    2006-07-15

    A number of CFD models are currently available to model gaseous explosions in complex geometries. Some of these tools allow the representation of complex environments within hydrocarbon production plants. In certain explosion scenarios, a correction is usually made for the presence of buildings and other complexities by using crude approximations to obtain realistic estimates of explosion behaviour as can be found when predicting the strength of blast waves resulting from initial explosions. With the advance of computational technology, and greater availability of computing power, computational fluid dynamics (CFD) tools are becoming increasingly available for solving such a wide range of explosion problems. A CFD-based explosion code - FLACS can, for instance, be confidently used to understand the impact of blast overpressures in a plant environment consisting of obstacles such as buildings, structures, and pipes. With its porosity concept representing geometry details smaller than the grid, FLACS can represent geometry well, even when using coarse grid resolutions. The performance of FLACS has been evaluated using a wide range of field data. In the present paper, the concept of computational fluid dynamics (CFD) and its application to gas explosion prediction is presented. Furthermore, the predictive capabilities of CFD-based gaseous explosion simulators are demonstrated using FLACS. Details about the FLACS-code, some extensions made to FLACS, model validation exercises, application, and some results from blast load prediction within an industrial facility are presented. (orig.)

  6. Models of the Intergalactic Gas in Stephan's Quintet

    CERN Document Server

    Hwang, Jeong-Sun; Renaud, Florent; Appleton, Philip N

    2009-01-01

    We use smoothed particle hydrodynamics (SPH) models to study the large-scale morphology and dynamical evolution of the intergalactic gas in Stephan's Quintet, and compare to multiwavelength observations. Specifically, we model the formation of the hot X-ray gas, the large-scale shock, and emission line gas as the result of NGC 7318b colliding with the group. We also reproduce the N-body model of Renaud and Appleton for the tidal structures in the group.

  7. Critical-like behavior in a lattice gas model

    CERN Document Server

    Wieloch, A; Lukasik, J; Pawlowski, P; Pietrzak, T; Trautmann, W

    2010-01-01

    ALADIN multifragmentation data show features characteristic of a critical behavior, which are very well reproduced by a bond percolation model. This suggests, in the context of the lattice gas model, that fragments are formed at nearly normal nuclear densities and temperatures corresponding to the Kertesz line. Calculations performed with a lattice gas model have shown that similarly good reproduction of the data can also be achieved at lower densities, particularly in the liquid-gas coexistence region.

  8. Updated collider and direct detection constraints on Dark Matter models for the Galactic Center gamma-ray excess

    Science.gov (United States)

    Escudero, Miguel; Hooper, Dan; Witte, Samuel J.

    2017-02-01

    Utilizing an exhaustive set of simplified models, we revisit dark matter scenarios potentially capable of generating the observed Galactic Center gamma-ray excess, updating constraints from the LUX and PandaX-II experiments, as well as from the LHC and other colliders. We identify a variety of pseudoscalar mediated models that remain consistent with all constraints. In contrast, dark matter candidates which annihilate through a spin-1 mediator are ruled out by direct detection constraints unless the mass of the mediator is near an annihilation resonance, or the mediator has a purely vector coupling to the dark matter and a purely axial coupling to Standard Model fermions. All scenarios in which the dark matter annihilates through t-channel processes are now ruled out by a combination of the constraints from LUX/PandaX-II and the LHC.

  9. Updated Collider and Direct Detection Constraints on Dark Matter Models for the Galactic Center Gamma-Ray Excess

    Energy Technology Data Exchange (ETDEWEB)

    Escudero, Miguel [Valencia U., IFIC; Hooper, Dan [Fermilab; Witte, Samuel J. [UCLA

    2017-02-20

    Utilizing an exhaustive set of simplified models, we revisit dark matter scenarios potentially capable of generating the observed Galactic Center gamma-ray excess, updating constraints from the LUX and PandaX-II experiments, as well as from the LHC and other colliders. We identify a variety of pseudoscalar mediated models that remain consistent with all constraints. In contrast, dark matter candidates which annihilate through a spin-1 mediator are ruled out by direct detection constraints unless the mass of the mediator is near an annihilation resonance, or the mediator has a purely vector coupling to the dark matter and a purely axial coupling to Standard Model fermions. All scenarios in which the dark matter annihilates through $t$-channel processes are now ruled out by a combination of the constraints from LUX/PandaX-II and the LHC.

  10. A stoichiometric producer-grazer model incorporating the effects of excess food-nutrient content on consumer dynamics.

    Science.gov (United States)

    Peace, Angela; Zhao, Yuqin; Loladze, Irakli; Elser, James J; Kuang, Yang

    2013-08-01

    There has been important progress in understanding ecological dynamics through the development of the theory of ecological stoichiometry. For example, modeling under this framework allows food quality to affect consumer dynamics. While the effects of nutrient deficiency on consumer growth are well understood, recent discoveries in ecological stoichiometry suggest that consumer dynamics are not only affected by insufficient food nutrient content (low phosphorus (P): carbon (C) ratio) but also by excess food nutrient content (high P:C). This phenomenon is known as the stoichiometric knife edge, in which animal growth is reduced not only by food with low P content but also by food with high P content, and needs to be incorporated into mathematical models. Here we present a Lotka-Volterra type model to investigate the growth response of Daphnia to algae of varying P:C ratios capturing the mechanism of the stoichiometric knife edge.

  11. Adsorption modeling for off-gas treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ladshaw, A.; Sharma, K.; Yiacoumi, S.; Tsouris, C. [Georgia Institute of Technology, Atlanta, GA 30332-0459 (United States); De Paoli, D.W. [Oak Ridge National Laboratory: Oak Ridge, TN 37831-6181 (United States)

    2013-07-01

    Off-gas generated from the reprocessing of used nuclear fuel contains a mixture of several radioactive gases including {sup 129}I{sub 2}, {sup 85}Kr, HTO, and {sup 14}CO{sub 2}. Over the past few decades, various separation and recovery processes have been studied for capturing these gases. Adsorption data for gaseous mixtures of species can be difficult to determine experimentally. Therefore, procedures capable of predicting the adsorption behavior of mixtures need to be developed from the individual isotherms of each of the pure species. A particular isotherm model of interest for the pure species is the Generalized Statistical Thermodynamic Adsorption isotherm. This model contains an adjustable number of parameters and will therefore describe a wide range of adsorption isotherms for a variety of components. A code has been developed in C++ to perform the non-linear regression analysis necessary for the determination of the isotherm parameters, as well as the least number of parameters needed to describe an entire set of data. (authors)

  12. Modeling UK Natural Gas Prices when Gas Prices Periodically Decouple from the Oil Price

    OpenAIRE

    2015-01-01

    When natural gas prices are subject to periodic decoupling from oil prices, for instance due to peak-load pricing, conventional linear models of price dynamics such as the Vector Error Correction Model (VECM) can lead to erroneous inferences about cointegration relationships, price adjustments and relative values. We propose the use of regime-switching models to address these issues. Our regime switching model uses price data to infer whether pricing is oil-driven (integrated) or gas-specific...

  13. Validation of spectral gas radiation models under oxyfuel conditions. Part A: Gas cell experiments

    DEFF Research Database (Denmark)

    Becher, Valentin; Clausen, Sønnik; Fateev, Alexander;

    2011-01-01

    AbstractCombustion of hydrocarbon fuels with pure oxygen results in a different flue gas composition as combustion with air. Standard CFD spectral gas radiation models for air combustion are out of their validity range. The series of three articles provides a common spectral basis for the validat......AbstractCombustion of hydrocarbon fuels with pure oxygen results in a different flue gas composition as combustion with air. Standard CFD spectral gas radiation models for air combustion are out of their validity range. The series of three articles provides a common spectral basis...

  14. GASCAP: Wellhead Gas Productive Capacity Model documentation, June 1993

    Energy Technology Data Exchange (ETDEWEB)

    1993-07-01

    The Wellhead Gas Productive Capacity Model (GASCAP) has been developed by EIA to provide a historical analysis of the monthly productive capacity of natural gas at the wellhead and a projection of monthly capacity for 2 years into the future. The impact of drilling, oil and gas price assumptions, and demand on gas productive capacity are examined. Both gas-well gas and oil-well gas are included. Oil-well gas productive capacity is estimated separately and then combined with the gas-well gas productive capacity. This documentation report provides a general overview of the GASCAP Model, describes the underlying data base, provides technical descriptions of the component models, diagrams the system and subsystem flow, describes the equations, and provides definitions and sources of all variables used in the system. This documentation report is provided to enable users of EIA projections generated by GASCAP to understand the underlying procedures used and to replicate the models and solutions. This report should be of particular interest to those in the Congress, Federal and State agencies, industry, and the academic community, who are concerned with the future availability of natural gas.

  15. Modelling combustion reactions for gas flaring and its resulting emissions

    Directory of Open Access Journals (Sweden)

    O. Saheed Ismail

    2016-07-01

    Full Text Available Flaring of associated petroleum gas is an age long environmental concern which remains unabated. Flaring of gas maybe a very efficient combustion process especially steam/air assisted flare and more economical than utilization in some oil fields. However, it has serious implications for the environment. This study considered different reaction types and operating conditions for gas flaring. Six combustion equations were generated using the mass balance concept with varying air and combustion efficiency. These equations were coded with a computer program using 12 natural gas samples of different chemical composition and origin to predict the pattern of emission species from gas flaring. The effect of key parameters on the emission output is also shown. CO2, CO, NO, NO2 and SO2 are the anticipated non-hydrocarbon emissions of environmental concern. Results show that the quantity and pattern of these chemical species depended on percentage excess/deficiency of stoichiometric air, natural gas type, reaction type, carbon mass content, impurities, combustion efficiency of the flare system etc. These emissions degrade the environment and human life, so knowing the emission types, pattern and flaring conditions that this study predicts is of paramount importance to governments, environmental agencies and the oil and gas industry.

  16. Adjusting for overdispersion in piecewise exponential regression models to estimate excess mortality rate in population-based research

    Directory of Open Access Journals (Sweden)

    Miguel Angel Luque-Fernandez

    2016-10-01

    Full Text Available Abstract Background In population-based cancer research, piecewise exponential regression models are used to derive adjusted estimates of excess mortality due to cancer using the Poisson generalized linear modelling framework. However, the assumption that the conditional mean and variance of the rate parameter given the set of covariates x i are equal is strong and may fail to account for overdispersion given the variability of the rate parameter (the variance exceeds the mean. Using an empirical example, we aimed to describe simple methods to test and correct for overdispersion. Methods We used a regression-based score test for overdispersion under the relative survival framework and proposed different approaches to correct for overdispersion including a quasi-likelihood, robust standard errors estimation, negative binomial regression and flexible piecewise modelling. Results All piecewise exponential regression models showed the presence of significant inherent overdispersion (p-value <0.001. However, the flexible piecewise exponential model showed the smallest overdispersion parameter (3.2 versus 21.3 for non-flexible piecewise exponential models. Conclusion We showed that there were no major differences between methods. However, using a flexible piecewise regression modelling, with either a quasi-likelihood or robust standard errors, was the best approach as it deals with both, overdispersion due to model misspecification and true or inherent overdispersion.

  17. Forecasting natural gas consumption in China by Bayesian Model Averaging

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2015-11-01

    Full Text Available With rapid growth of natural gas consumption in China, it is in urgent need of more accurate and reliable models to make a reasonable forecast. Considering the limitations of the single model and the model uncertainty, this paper presents a combinative method to forecast natural gas consumption by Bayesian Model Averaging (BMA. It can effectively handle the uncertainty associated with model structure and parameters, and thus improves the forecasting accuracy. This paper chooses six variables for forecasting the natural gas consumption, including GDP, urban population, energy consumption structure, industrial structure, energy efficiency and exports of goods and services. The results show that comparing to Gray prediction model, Linear regression model and Artificial neural networks, the BMA method provides a flexible tool to forecast natural gas consumption that will have a rapid growth in the future. This study can provide insightful information on natural gas consumption in the future.

  18. The sigma-receptor antagonist BD-1063 decreases ethanol intake and reinforcement in animal models of excessive drinking.

    Science.gov (United States)

    Sabino, Valentina; Cottone, Pietro; Zhao, Yu; Iyer, Malliga R; Steardo, Luca; Steardo, Luca; Rice, Kenner C; Conti, Bruno; Koob, George F; Zorrilla, Eric P

    2009-05-01

    Sigma-Receptors (SigRs) have been implicated in behavioral and appetitive effects of psychostimulants and may also modulate the motivating properties of ethanol. This study tested the hypothesis that SigRs modulate ethanol reinforcement and contribute to excessive ethanol intake. The effects of subcutaneous treatment with the potent, selective Sig-1R antagonist BD-1063 on operant ethanol self-administration were studied in two models of excessive drinking-Sardinian alcohol-preferring (sP) rats and acutely withdrawn ethanol-dependent Wistar rats-and compared to ethanol self-administration in nondependent Wistar controls. To assess the specificity of action, the effects of BD-1063 on self-administration of an equally reinforcing saccharin solution were determined in Wistar and sP rats. Gene expression of Sig-1R in reward-related brain areas implicated in ethanol reinforcement was compared between ethanol-naive sP and Wistar rats and withdrawn ethanol-dependent Wistar rats. BD-1063 dose dependently reduced ethanol self-administration in sP rats (3.3-11 mg/kg) and withdrawn, dependent Wistar rats (4-11 mg/kg) at doses that did not modify mean ethanol self-administration in nondependent Wistar controls. BD-1063 did not reduce concurrent water self-administration and did not comparably suppress saccharin self-administration, suggesting selectivity of action. BD-1063 also reduced the breakpoints of sP rats to work for ethanol under a progressive-ratio reinforcement schedule. Ethanol-naive sP rats and 24-h withdrawn, dependent Wistar rats showed reduced Sig-1R mRNA expression in the nucleus accumbens. The results suggest that SigR systems may contribute to innate or ethanol-induced increases in susceptibility to self-administer high ethanol levels, identifying a potential neuroadaptive mechanism contributing to excessive drinking and a therapeutic target for alcohol abuse and dependence.

  19. Interpretation of 750 GeV Diphoton Excess at LHC in Singlet Extension of Color-octet Neutrino Mass Model

    CERN Document Server

    Ding, Ran; Liao, Yi; Ma, Xiao-Dong

    2016-01-01

    We propose that the possible 750 GeV diphoton excess can be explained in the color-octet neutrino mass model extended with a scalar singlet $\\Phi$. The model generally contains $N_s$ species of color-octet, electroweak doublet scalars $S$ and $N_f$ species of color-octet, electroweak triplet $\\chi$ or singlet $\\rho$ fermions. While both scalars and fermions contribute to the production of $\\Phi$ through gluon fusion, only the charged members induce the diphoton decay of $\\Phi$. The diphoton rate can be significantly enhanced due to interference between the scalar and fermion loops. We show that the diphoton cross section can be from 3 to 10 fb for O(TeV) color-octet particles while evading all current LHC limits.

  20. Interpretation of 750 GeV diphoton excess at LHC in singlet extension of color-octet neutrino mass model

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Ran [Peking University, Center for High Energy Physics, Beijing (China); Han, Zhi-Long; Ma, Xiao-Dong [Nankai University, School of Physics, Tianjin (China); Liao, Yi [Peking University, Center for High Energy Physics, Beijing (China); Nankai University, School of Physics, Tianjin (China); Chinese Academy of Sciences, State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China)

    2016-04-15

    We propose that the possible 750 GeV diphoton excess can be explained in the color-octet neutrino mass model extended with a scalar singlet Φ. The model generally contains N{sub s} species of color-octet, electroweak doublet scalars S and N{sub f} species of color-octet, electroweak triplet χ or singlet ρ fermions. While both scalars and fermions contribute to the production of Φ through gluon fusion, only the charged members induce the diphoton decay of Φ. The diphoton rate can be significantly enhanced due to interference between the scalar and fermion loops.We show that the diphoton cross section can be from 3 to 10 fb for O(TeV) color-octet particles while evading all current LHC limits. (orig.)

  1. 3D modeling of gas/water distribution in water-bearing carbonate gas reservoirs: the Longwangmiao gas field, China

    Science.gov (United States)

    Ou, Chenghua; Li, ChaoChun; Ma, Zhonggao

    2016-10-01

    A water-bearing carbonate gas reservoir is an important natural gas resource being developed worldwide. Due to the long-term water/rock/gas interaction during geological evolution, complex gas/water distribution has formed under the superposed effect of sedimentary facies, reservoir space facies and gravity difference of fluid facies. In view of these challenges, on the basis of the conventional three-stage modeling method, this paper presents a modelling method controlled by four-stage facies to develop 3D model of a water-bearing carbonate gas reservoir. Key to this method is the reservoir property modelling controlled by two-stage facies, and the fluid property modelling controlled by another two-stage facies. The prerequisite of this method is a reliable database obtained from solid geological investigation. On the basis of illustrating the principles of the modelling method controlled by four-stage facies, this paper further implements systematically modeling of the heterogeneous gas/water distribution of the Longwangmiao carbonate formation in the Moxi-Gaoshiti area, Sichuan basin, China.

  2. Numerical model of compressible gas flow in soil pollution control

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the theory of fluid dynamics in porous media, a numerical model of gas flow in unsaturated zone is developed with the consideration of gas density change due to variation of air pressure. This model is characterized of its wider range of availability. The accuracy of this numerical model is analyzed through comparison with modeling results by previous model with presumption of little pressure variation and the validity of this numerical model is shown. Thus it provides basis for the designing and management of landfill gas control system or soil vapor ex.action system in soil pollution control.

  3. Open Source Web GIS Solutions in Disaster Management – with Special Emphasis on Inland Excess Water Modeling

    Directory of Open Access Journals (Sweden)

    Juhász Levente

    2016-06-01

    Full Text Available In recent years, the increased frequency of inland excess water in the Carpathian Basin gets more and more attention. The authors developed a web based pilot application for disaster management, with special emphasis on inland excess water hazard management. Free and open source software was used to generate a model, and our work was based on Web GIS standards (OGC, which makes further development possible. The developed Web GIS application provides functions to support the data collection regarding channels and ditches, and on-line hydrological analysis based on OGC Web Processing Services (WPS. Hydrological analysis aims to visualize the areas potentially at risk, depending on different precipitation quantities and various values of influencing factors. In order to run the prototype a sample data set was gathered including reference maps, technical parameters and current condition of canals and ditches. The methodology of crowdsourcing can produce valuable Volunteered Geographic Information (VGI that can fulfill the data requirements of disaster management applications. The prototype supports Crowdsourcing in the following aspects: free user access to the system’s analysis functionality, stakeholders may digitize the position of ditches, modify the status of the existing ditch system according to current conditions and add or modify parameters relevant for the analysis. The application demonstrated the usability of stakeholder generated geographic information and web processing for disaster management. The idea of integrating user-generated data into the various tasks of a disaster management agency is promising. However, maintaining data quality and standards compliance remain important issues.

  4. Excess pregnancy weight gain leads to early indications of metabolic syndrome in a swine model of fetal programming.

    Science.gov (United States)

    Arentson-Lantz, Emily J; Buhman, Kimberly K; Ajuwon, Kolapo; Donkin, Shawn S

    2014-03-01

    Few data exist on the impact of maternal weight gain on offspring despite evidence demonstrating that early-life environment precipitates risks for metabolic syndrome. We hypothesized that excessive weight gain during pregnancy results in programming that predisposes offspring to obesity and metabolic syndrome. We further hypothesized that early postweaning nutrition alters the effects of maternal weight gain on indications of metabolic syndrome in offspring. Pregnant sows and their offspring were used for these experiments due to similarities with human digestive physiology, metabolism, and neonatal development. First parity sows fed a high-energy (maternal nutrition high energy [MatHE]) diet gained 12.4 kg (42%) more weight during pregnancy than sows fed a normal energy (maternal nutrition normal energy) diet. Birth weight and litter characteristics did not differ, but offspring MatHE gilts weighed more (P pregnancy. These data indicate that excessive gestational weight gain during pregnancy in a pig model promotes early indications of metabolic syndrome in offspring that are further promoted by a high-energy postweaning diet.

  5. Modeling of Fission Gas Release in UO2

    Energy Technology Data Exchange (ETDEWEB)

    MH Krohn

    2006-01-23

    A two-stage gas release model was examined to determine if it could provide a physically realistic and accurate model for fission gas release under Prometheus conditions. The single-stage Booth model [1], which is often used to calculate fission gas release, is considered to be oversimplified and not representative of the mechanisms that occur during fission gas release. Two-stage gas release models require saturation at the grain boundaries before gas is release, leading to a time delay in release of gases generated in the fuel. Two versions of a two-stage model developed by Forsberg and Massih [2] were implemented using Mathcad [3]. The original Forsbers and Massih model [2] and a modified version of the Forsberg and Massih model that is used in a commercially available fuel performance code (FRAPCON-3) [4] were examined. After an examination of these models, it is apparent that without further development and validation neither of these models should be used to calculate fission gas release under Prometheus-type conditions. There is too much uncertainty in the input parameters used in the models. In addition. the data used to tune the modified Forsberg and Massih model (FRAPCON-3) was collected under commercial reactor conditions, which will have higher fission rates relative to Prometheus conditions [4].

  6. Analyze and solve the problem of excessive hydrogen sulfide content in CO2 emissions gas%CO2排放气中H2S超标的问题分析及解决

    Institute of Scientific and Technical Information of China (English)

    乔景红

    2013-01-01

    针对低温甲醇洗系统中排放气中H2S超标的问题,采用人、机、料、法、环的方法进行分析,并对分析出的主要原因制定相应的措施,使排放气的H2S含量达到设计值以内,解决了排放气中H2S超标的问题.%For the problem of excessive hydrogen sulfide as the emission gas in low temperature methanol washing system. This paper analyses the causes of this phenomena by human, machine, material, method and environment. Some advice about how to ensure that the concentration of hydrogen sulfide in the setting within were put forward. In this way, The problem of excessive hydrogen sulfide as the emission gas was solved.

  7. A Mathematical Model of Coupled Gas Flow and Coal Deformation with Gas Diffusion and Klinkenberg Effects

    Science.gov (United States)

    Liu, Qingquan; Cheng, Yuanping; Zhou, Hongxing; Guo, Pinkun; An, Fenghua; Chen, Haidong

    2015-05-01

    The influence of gas diffusion behavior on gas flow and permeability evolution in coal seams is evaluated in this paper. Coalbed methane (CBM) reservoirs differ from conventional porous media and fractured gas reservoirs due to certain unique features, which lead to two distinct gas pressures: one in fractures and the other in the coal matrix. The latter pressure, also known as the sorption pressure, will be used in calculating sorption-based volume changes. The effective stress laws for single-porosity media is not suitable for CBM reservoirs, and the effective stress laws for multi-porosity media need to be applied. The realization of the above two points is based on the study of the two-phase state of gas migration (involving Fickian diffusion and Darcy flow) in a coal seam. Then, a general porosity and permeability model based on the P-M model is proposed to fit this phenomenon. Moreover, the Klinkenberg effect has been taken into account and set as a reference object. Finally, a coupled gas flow and coal deformation model is proposed and solved by using a finite element method. The numerical results indicate that the effects of gas diffusion behavior and Klinkenberg behavior can have a critical influence on the gas pressure, residual gas content, and permeability evolution during the entire methane degasification period, and the impacts of the two effects are of the same order of magnitude. Without considering the gas diffusion effect, the gas pressure and residual gas content will be underestimated, and the permeability will be overestimated.

  8. Development of gas turbines simplified mathematical models; Desenvolvimento de modelos matematicos simplificados das turbinas a gas

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Leonardo Vinicius; Mendes, Pedro Paulo C. [Escola Federal de Engenharia de Itajuba, MG (Brazil). Dept. de Eletrotecnica; Ferreira, Claudio [Agencia Nacional de Energia Eletrica (ANEEL), Brasilia, DF (Brazil)

    1999-07-01

    This paper presents the development and analysis of various mathematical models for gas turbine which can be incorporated to dynamic stability or to electric power systems. The work provides answers for questions such as: the dynamic behaviour of gas turbine driven generator unities, the influence of those equipment in the other elements and the best operational conditions for the equipment.

  9. A weakly compressible formulation for modelling liquid-gas sloshing

    CSIR Research Space (South Africa)

    Heyns, Johan A

    2012-09-01

    Full Text Available This study presents the development and extension of free-surface modelling techniques with the purpose of improving the modelling accuracy for liquid-gas sloshing. Considering high density ratio fluids under low Mach number conditions...

  10. A basic mathematical and numerical model for gas injection

    NARCIS (Netherlands)

    Molenaar, J.

    1996-01-01

    In this paper we discuss a mathematical model for gas storage processes. In addition we outline an approach for numerical simulations. The focus is on model assumptions and limitations with respect to the software to be developed.

  11. A basic mathematical and numerical model for gas injection

    NARCIS (Netherlands)

    J. Molenaar (Gijs)

    1996-01-01

    textabstractIn this paper we discuss a mathematical model for gas storage processes. In addition we outline an approach for numerical simulations. The focus is on model assumptions and limitations with respect to the software to be developed.

  12. Modeling biogenic gas bubbles formation and migration in coarse sand

    Science.gov (United States)

    Ye, S.

    2011-12-01

    Shujun Ye Department of Hydrosciences, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, China; sjye@nju.edu.cn Brent E. Sleep Department of Civil Engineering, University of Toronto, Toronto, ON, M5S 1A4 CANADA; sleep@ecf.utoronto.ca Methane gas generation in porous media was investigated in an anaerobic two-dimensional sand-filled cell. Inoculation of the lower portion of the cell with a methanogenic culture and addition of methanol to the bottom of the cell led to biomass growth and formation of a gas phase. The formation, migration, distribution and saturation of gases in the cell were visualized by the charge-coupled device (CCD) camera. Gas generated at the bottom of the cell in the biologically active zone moved upwards in discrete fingers, so that gas phase saturations (gas-filled fraction of void space) in the biologically active zone at the bottom of the cell did not exceed 40-50%, while gas accumulation at the top of the cell produced gas phase saturations as high as 80%. Macroscopic invasion percolation (MIP) at near pore scale[Glass, et al., 2001; Kueper and McWhorter, 1992]was used to model gas bubbles growth in porous media. The nonwetting phase migration pathway can be yielded directly by MIP. MIP was adopted to simulate the expansion, fragmentation, and mobilization of gas clusters in the cell. The production of gas, and gas phash saturations were simulated by a continuum model - compositional simulator (COMPSIM) [Sleep and Sykes, 1993]. So a combination of a continuum model and a MIP model was used to simulate the formation, fragmentation and migration of biogenic gas bubbles. Key words: biogenic gas; two dimensional; porous media; MIP; COMPSIM

  13. Excess wind power

    DEFF Research Database (Denmark)

    Østergaard, Poul Alberg

    2005-01-01

    Expansion of wind power is an important element in Danish climate change abatement policy. Starting from a high penetration of approx 20% however, momentary excess production will become an important issue in the future. Through energy systems analyses using the EnergyPLAN model and economic...... analyses it is analysed how excess productions are better utilised; through conversion into hydrogen of through expansion of export connections thereby enabling sales. The results demonstrate that particularly hydrogen production is unviable under current costs but transmission expansion could...... be profitable particularly if transmission and dispatch companies operate under a feed-in tariff system....

  14. Excessive activity of cathepsin K is associated with cartilage defects in a zebrafish model of mucolipidosis II

    Directory of Open Access Journals (Sweden)

    Aaron C. Petrey

    2012-03-01

    The severe pediatric disorder mucolipidosis II (ML-II; also known as I-cell disease is caused by defects in mannose 6-phosphate (Man-6-P biosynthesis. Patients with ML-II exhibit multiple developmental defects, including skeletal, craniofacial and joint abnormalities. To date, the molecular mechanisms that underlie these clinical manifestations are poorly understood. Taking advantage of a zebrafish model of ML-II, we previously showed that the cartilage morphogenesis defects in this model are associated with altered chondrocyte differentiation and excessive deposition of type II collagen, indicating that aspects of development that rely on proper extracellular matrix homeostasis are sensitive to decreases in Man-6-P biosynthesis. To further investigate the molecular bases for the cartilage phenotypes, we analyzed the transcript abundance of several genes in chondrocyte-enriched cell populations isolated from wild-type and ML-II zebrafish embryos. Increased levels of cathepsin and matrix metalloproteinase (MMP transcripts were noted in ML-II cell populations. This increase in transcript abundance corresponded with elevated and sustained activity of several cathepsins (K, L and S and MMP-13 during early development. Unlike MMP-13, for which higher levels of protein were detected, the sustained activity of cathepsin K at later stages seemed to result from its abnormal processing and activation. Inhibition of cathepsin K activity by pharmacological or genetic means not only reduced the activity of this enzyme but led to a broad reduction in additional protease activity, significant correction of the cartilage morphogenesis phenotype and reduced type II collagen staining in ML-II embryos. Our findings suggest a central role for excessive cathepsin K activity in the developmental aspects of ML-II cartilage pathogenesis and highlight the utility of the zebrafish system to address the biochemical underpinnings of metabolic disease.

  15. Modeling the Phase Composition of Gas Condensate in Pipelines

    Science.gov (United States)

    Dudin, S. M.; Zemenkov, Yu D.; Shabarov, A. B.

    2016-10-01

    Gas condensate fields demonstrate a number of thermodynamic characteristics to be considered when they are developed, as well as when gas condensate is transported and processed. A complicated phase behavior of the gas condensate system, as well as the dependence of the extracted raw materials on the phase state of the deposit other conditions being equal, is a key aspect. Therefore, when designing gas condensate lines the crucial task is to select the most appropriate methods of calculating thermophysical properties and phase equilibrium of the transported gas condensate. The paper describes a physical-mathematical model of a gas-liquid flow in the gas condensate line. It was developed based on balance equations of conservation of mass, impulse and energy of the transported medium within the framework of a quasi-1D approach. Constitutive relationships are given separately, and practical recommendations on how to apply the research results are provided as well.

  16. Development of a gas systems analysis model (GSAM)

    Energy Technology Data Exchange (ETDEWEB)

    Godec, M.L. [IFC Resources Inc., Fairfax, VA (United States)

    1995-04-01

    The objectives of developing a Gas Systems Analysis Model (GSAM) are to create a comprehensive, non-proprietary, PC based model of domestic gas industry activity. The system is capable of assessing the impacts of various changes in the natural gas system within North America. The individual and collective impacts due to changes in technology and economic conditions are explicitly modeled in GSAM. Major gas resources are all modeled, including conventional, tight, Devonian Shale, coalbed methane, and low-quality gas sources. The modeling system asseses all key components of the gas industry, including available resources, exploration, drilling, completion, production, and processing practices, both for now and in the future. The model similarly assesses the distribution, storage, and utilization of natural gas in a dynamic market-based analytical structure. GSAM is designed to provide METC managers with a tool to project the impacts of future research, development, and demonstration (RD&D) benefits in order to determine priorities in a rapidly changing, market-driven gas industry.

  17. Serviceability limit state related to excessive lateral deformations to account for infill walls in the structural model

    Directory of Open Access Journals (Sweden)

    G. M. S. ALVA

    Full Text Available Brazilian Codes NBR 6118 and NBR 15575 provide practical values for interstory drift limits applied to conventional modeling in order to prevent negative effects in masonry infill walls caused by excessive lateral deformability, however these codes do not account for infill walls in the structural model. The inclusion of infill walls in the proposed model allows for a quantitative evaluation of structural stresses in these walls and an assessment of cracking in these elements (sliding shear diagonal tension and diagonal compression cracking. This paper presents the results of simulations of single-story one-bay infilled R/C frames. The main objective is to show how to check the serviceability limit states under lateral loads when the infill walls are included in the modeling. The results of numerical simulations allowed for an evaluation of stresses and the probable cracking pattern in infill walls. The results also allowed an identification of some advantages and limitations of the NBR 6118 practical procedure based on interstory drift limits.

  18. LHC di-photon excess and gauge coupling unification in extra Z{sup '} heterotic-string derived models

    Energy Technology Data Exchange (ETDEWEB)

    Ashfaque, J. [University of Liverpool, Department of Mathematical Sciences, Liverpool (United Kingdom); Delle Rose, L. [University of Southampton, School of Physics and Astronomy, Southampton (United Kingdom); Faraggi, A.E. [Rutherford Appleton Laboratory, Department of Particle Physics, Chilton, Didcot (United Kingdom); Marzo, C. [Universita del Salento, Dipartimento di Matematica e Fisica ' ' Ennio De Giorgi' ' , Lecce (Italy); INFN, Lecce (Italy)

    2016-10-15

    A di-photon excess at the LHC can be explained as a Standard Model singlet that is produced and decays by heavy vector-like colour triplets and electroweak doublets in one-loop diagrams. The characteristics of the required spectrum are well motivated in heterotic-string constructions that allow for a light Z{sup '}. Anomaly cancellation of the U(1){sub Z'} symmetry requires the existence of the Standard Model singlet and vector-like states in the vicinity of the U(1){sub Z'} breaking scale. In this paper we show that the agreement with the gauge coupling data at one-loop is identical to the case of the Minimal Supersymmetric Standard Model, owing to cancellations between the additional states. We further show that effects arising from heavy thresholds may push the supersymmetric spectrum beyond the reach of the LHC, while maintaining the agreement with the gauge coupling data. We show that the string-inspired model can indeed produce an observable signal and discuss the feasibility of obtaining viable scalar mass spectrum. (orig.)

  19. The LHC di-photon excess and Gauge Coupling Unification in Extra $Z^\\prime$ Heterotic-String Derived Models

    CERN Document Server

    Ashfaque, J; Faraggi, A E; Marzo, C

    2016-01-01

    The di-photon excess observed at the LHC can be explained as a Standard Model singlet that is produced and decays by heavy vector-like colour triplets and electroweak doublets in one-loop diagrams. The characteristics of the required spectrum are well motivated in heterotic-string constructions that allow for a light $Z^\\prime$. Anomaly cancellation of the $U(1)_{Z^\\prime}$ symmetry requires the existence of the Standard Model singlet and vector-like states in the vicinity of the $U(1)_{Z^\\prime}$ breaking scale. In this paper we show that the agreement with the gauge coupling data at one-loop is identical to the case of the Minimal Supersymmetric Standard Model, owing to cancellations between the additional states. We further show that effects arising from heavy thresholds may push the supersymmetric spectrum beyond the reach of the LHC, while maintaining the agreement with the gauge coupling data. We show that the string inspired model can indeed account for the observed signal and discuss the feasibility o...

  20. A Game-Dynamic Model of Gas Transportation Routes and Its Application to the Turkish Gas Market [Updated November 2003

    OpenAIRE

    Klaassen, G.; Matrosov, I.; Roehrl, R.A.; A.M. Tarasyev

    2003-01-01

    The purpose of this paper is to study an optimal structure of a system of international gas pipelines competing for a gas market. We develop a game-dynamic model of the operation of several interacting gas pipeline projects with project owners acting as players in the game. The model treats the projects' commercialization times major players' controls. Current quantities of gas supply are modeled as approximations of Nash equilibrium points in instantaneous "gas supply games", in which each p...

  1. Model documentation: Natural gas transmission and distribution model of the National Energy Modeling System. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-02-17

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of integrated Analysis and Forecasting of the Energy information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. The NGTDM is the model within the NEMS that represents the transmission, distribution, and pricing of natural gas. The model also includes representations of the end-use demand for natural gas, the production of domestic natural gas, and the availability of natural gas traded on the international market based on information received from other NEMS models. The NGTDM determines the flow of natural gas in an aggregate, domestic pipeline network, connecting domestic and foreign supply regions with 12 demand regions. The methodology employed allows the analysis of impacts of regional capacity constraints in the interstate natural gas pipeline network and the identification of pipeline capacity expansion requirements. There is an explicit representation of core and noncore markets for natural gas transmission and distribution services, and the key components of pipeline tariffs are represented in a pricing algorithm. Natural gas pricing and flow patterns are derived by obtaining a market equilibrium across the three main elements of the natural gas market: the supply element, the demand element, and the transmission and distribution network that links them. The NGTDM consists of four modules: the Annual Flow Module, the Capacity F-expansion Module, the Pipeline Tariff Module, and the Distributor Tariff Module. A model abstract is provided in Appendix A.

  2. The 750 GeV di-photon LHC excess and extra Z's in heterotic-string derived models

    Energy Technology Data Exchange (ETDEWEB)

    Faraggi, Alon E. [University of Liverpool, Department of Mathematical Sciences, Liverpool (United Kingdom); Rizos, John [University of Ioannina, Department of Physics, Ioannina (Greece)

    2016-03-15

    The ATLAS and CMS collaborations recently recorded possible di-photon excess at 750 GeV and a less significant di-boson excess around 1.9 TeV. Such excesses may be produced in heterotic string derived Z' models, where the di-photon excess may be connected with the Standard Model singlet scalar responsible for the Z' symmetry breaking, whereas the di-boson excess arises from production of the extra vector boson. Additional vector-like states in the string Z' model are instrumental to explain the relatively large width of the di-photon events and mandated by anomaly cancellation to be in the vicinity of the Z' breaking scale. Wilson line breaking of the non-Abelian gauge symmetries in the string models naturally gives rise to dark matter candidates. Future collider experiments will discriminate between the high-scale heterotic-string models, which preserve the perturbative unification paradigm indicated by the Standard Model data, versus the low scale string models.We also discuss the possibility for the production of the diphoton events with high scale U(1){sub Z'} breaking. (orig.)

  3. Forecasting China's natural gas consumption based on a combination model

    Institute of Scientific and Technical Information of China (English)

    Gang Xu; Weiguo Wang

    2010-01-01

    Ensuring a sufficient energy supply is essential to a country.Natural gas constitutes a vital part in energy supply and therefore forecasting natural gas consumption reliably and accurately is an essential part of a country's energy policy.Over the years,studies have shown that a combinative model gives better projected results compared to a single model.In this study,we used Polynomial Curve and Moving Average Combination Projection (PCMACP) model to estimate the future natural gas consumption in China from 2009 to 2015.The new proposed PCMACP model shows more reliable and accurate results:its Mean Absolute Percentage Error (MAPE) is less than those of any previous models within the investigated range.According to the PCMACP model,the average annual growth rate will increase for the next 7 years and the amount of natural gas consumption will reach 171600 million cubic meters in 2015 in China.

  4. A global fit of the $\\gamma$-ray galactic center excess within the scalar singlet Higgs portal model

    CERN Document Server

    Cuoco, Alessandro; Heisig, Jan; Krämer, Michael

    2016-01-01

    We analyse the excess in the $\\gamma$-ray emission from the center of our galaxy observed by Fermi-LAT in terms of dark matter annihilation within the scalar Higgs portal model. In particular, we include the astrophysical uncertainties from the dark matter distribution and allow for unspecified additional dark matter components. We demonstrate through a detailed numerical fit that the strength and shape of the $\\gamma$-ray spectrum can indeed be described by the model in various regions of dark matter masses and couplings. Constraints from invisible Higgs decays, direct dark matter searches, indirect searches in dwarf galaxies and for $\\gamma$-ray lines, and constraints from the dark matter relic density reduce the parameter space to dark matter masses near the Higgs resonance. We find two viable regions: one where the Higgs-dark matter coupling is of ${\\cal O}(10^{-2})$, and an additional dark matter component beyond the scalar WIMP of our model is preferred, and one region where the Higgs-dark matter coupli...

  5. Evaluation of excess carbon 14 and strontium 90 data for suitability to test two-dimensional stratospheric models

    Science.gov (United States)

    Johnston, Harold

    1989-12-01

    From reports by the Atomic Energy Commission concerning the atmospheric distribution of radionucleides following the nuclear bomb tests of 1958-1959 and 1961-1962, excess carbon 14 data from the period 1959-1970 and strontium 90 data from 1963-1967 are reviewed for possible use as inert tracers to test two-dimensional stratospheric-tropospheric models. Contrary to some views expressed in the literature, it is concluded that the carbon 14 data are suitable to test (1) the altitude (at 4 latitudes) of the transition region between troposphere and stratosphere with respect to transport of an inert tracer, (2) some aspects of transport between the northern and southern hemispheres, (3) horizontal and vertical transport as the vertical profile between 4.5 and 33 km and at 31°N evolves from a skewed Gaussian in 1963 to an almost stair-step profile in 1966, and (4) the long-term one-dimensional aspect of a two-dimensional model over the period 1966-1970. More tentatively, it is concluded that the strontium 90 data may be used as a model for the distribution and gross settling rate of the natural stratospheric aerosol layer between 15 and 25 km. Data from difficultly obtained laboratory reports and suggested initial conditions and boundary conditions are included as a microfiche supplement to this paper.

  6. Class of Higgs-portal dark matter models in the light of gamma-ray excess from galactic center

    Directory of Open Access Journals (Sweden)

    Tanmoy Mondal

    2015-05-01

    Full Text Available Recently the study of anomalous gamma-ray emission in the regions surrounding the galactic center has drawn a lot of attention as it points out that the excess of ∼1–3 GeV gamma-ray in the low latitude is consistent with the emission expected from annihilating dark matter. The best-fit to the gamma-ray spectrum corresponds to dark matter (DM candidate having mass in the range ∼31–40 GeV annihilating into bb¯-pair with cross-section 〈σv〉=(1.4–2.0×10−26 cm3s−1. We have shown that the Higgs-portal dark matter models in presence of scalar resonance (in the annihilation channel are well-suited for explaining these phenomena. In addition, the parameter space of these models also satisfies constraints from the LHC Higgs searches, relic abundance and direct detection experiments. We also comment on real singlet scalar Higgs-portal DM model which is found to be incompatible with the recent analysis.

  7. $B\\to K^* \\mu^+ \\mu^-$, muon $g-2$, and 750 GeV diphoton excesses in a leptoquark model

    CERN Document Server

    Chen, Chuan-Hung; Okada, Hiroshi

    2016-01-01

    More than $3\\sigma$ deviation from the standard model are observed in the angular observable $P'_5$ of $B\\to K^* \\mu^+ \\mu^-$ and muon $g-2$; and a new resonance with a mass of 750 GeV is indicated by ATLAS and CMS. To resolve these anomalies, we extend the standard model by adding one Higgs singlet and two leptoqaurks. It is found that the signal strength for diphoton Higgs decay can have a significant deviation from unity and is within the errors of data. Although $\\ell_i \\to \\ell_j \\gamma$ put severe bounds on some couplings, it is found that the excesses of $P'_5$ and muon $g-2$ can still be explained and accommodate to the measurement of $B_s\\to \\mu^+ \\mu^-$ in this model. The large cross section for producing 750 GeV Higgs singlet and decaying to diphoton can be achieved when the trilinear couplings of Higgs singlet to leptoquarks are of ${\\cal O}(1)$ TeV and leptoquark mass $m_{LQ} \\leq 1$ TeV.

  8. Common inconsistencies in modeling gas transport in porous electrodes: The dusty-gas model and the Fick law

    Science.gov (United States)

    Bertei, A.; Nicolella, C.

    2015-04-01

    The paper shows as two assumptions typically made in modeling gas transport in solid oxide fuel cell electrodes, i.e., a) uniform pressure in the dusty-gas model, and b) validity of the Bosanquet formula in the Fick model, may lead to serious inconsistencies (such as molar fractions that do not sum up to one or fluxes that do not obey reaction stoichiometry), thus nullifying the efforts of the mechanistic modeling of transport phenomena. The nature of the inconsistent use of the models is explained with clear examples, then the correct implementation of the gas transport models is discussed. The study aims to promote a coherent physically-based modeling of gas transport phenomena in porous electrodes in order to assist their rational design.

  9. Natural gas distribution network modelling and leak minimization

    NARCIS (Netherlands)

    Westering, W.H.P. van; Hellendoorn, H.; Brasjen, B.J.; Linden, R.J.P. van der

    2014-01-01

    A gas network model has been constructed based on the steady-state Weymouth equation. A fast and robust solution algorithm is proposed and subsequently used to calculate all flows and pressures in a gas network with over 40,000 pipes. The obtained result is mathematically accurate within 0.1% and ha

  10. A simple artificial light-harvesting dyad as a model for excess energy dissipation on oxygenic photosynthesis

    NARCIS (Netherlands)

    Berera, R.; Herrero, C.; Stokkum, van I.H.M.; Vengris, M.; Kodis, G.; Palacios, R.E.; Amerongen, van H.; Grondelle, van R.; Gust, D.; Moore, T.A.; Moore, A.L.; Kennis, J.T.M.

    2006-01-01

    Under excess illumination, plant photosystem II dissipates excess energy through the quenching of chlorophyll fluorescence, a process known as nonphotochemical quenching. Activation of nonphotochemical quenching has been linked to the conversion of a carotenoid with a conjugation length of nine doub

  11. Data Processing Model of Coalmine Gas Early-Warning System

    Institute of Scientific and Technical Information of China (English)

    QIAN Jian-sheng; YIN Hong-sheng; LIU Xiu-rong; HUA Gang; XU Yong-gang

    2007-01-01

    The data processing mode is vital to the performance of an entire coalmine gas early-warning system, especially in real-time performance. Our objective was to present the structural features of coalmine gas data, so that the data could be processed at different priority levels in C language. Two different data processing models, one with priority and the other without priority, were built based on queuing theory. Their theoretical formulas were determined via a M/M/1 model in order to calculate average occupation time of each measuring point in an early-warning program. We validated the model with the gas early-warning system of the Huaibei Coalmine Group Corp. The results indicate that the average occupation time for gas data processing by using the queuing system model with priority is nearly 1/30 of that of the model without priority..

  12. Modelling and simulation of gas explosions in complex geometries

    Energy Technology Data Exchange (ETDEWEB)

    Saeter, Olav

    1998-12-31

    This thesis presents a three-dimensional Computational Fluid Dynamics (CFD) code (EXSIM94) for modelling and simulation of gas explosions in complex geometries. It gives the theory and validates the following sub-models : (1) the flow resistance and turbulence generation model for densely packed regions, (2) the flow resistance and turbulence generation model for single objects, and (3) the quasi-laminar combustion model. It is found that a simple model for flow resistance and turbulence generation in densely packed beds is able to reproduce the medium and large scale MERGE explosion experiments of the Commission of European Communities (CEC) within a band of factor 2. The model for a single representation is found to predict explosion pressure in better agreement with the experiments with a modified k-{epsilon} model. This modification also gives a slightly improved grid independence for realistic gas explosion approaches. One laminar model is found unsuitable for gas explosion modelling because of strong grid dependence. Another laminar model is found to be relatively grid independent and to work well in harmony with the turbulent combustion model. The code is validated against 40 realistic gas explosion experiments. It is relatively grid independent in predicting explosion pressure in different offshore geometries. It can predict the influence of ignition point location, vent arrangements, different geometries, scaling effects and gas reactivity. The validation study concludes with statistical and uncertainty analyses of the code performance. 98 refs., 96 figs, 12 tabs.

  13. Gas Deliverability Model with Different Vertical Wells Properties

    Directory of Open Access Journals (Sweden)

    L. Mucharam

    2003-11-01

    Full Text Available We present here a gas deliverability computational model for single reservoir with multi wells. The questions of how long the gas delivery can be sustained and how to estimate the plateau time are discussed here. In order to answer such a question, in this case, a coupling method which consists of material balance method and gas flow equation method is developed by assuming no water influx in the reservoir. Given the rate and the minimum pressure of gas at the processing plant, the gas pressure at the wellhead and at the bottom hole can be obtained. From here, the estimation of the gas deliverability can be done. In this paper we obtain a computational method which gives direct computation for pressure drop from the processing plant to the wells, taking into account different well behavior. Here AOF technique is used for obtaining gas rate in each well. Further Tian & Adewumi correlation is applied for pressure drop model along vertical and horizontal pipes and Runge-Kutta method is chosen to compute the well head and bottom hole pressures in each well which then being used to estimate the plateau times. We obtain here direct computational scheme of gas deliverability from reservoir to processing plant for single reservoir with multi-wells properties. Computational results give different profiles (i.e. gas rate, plateau and production time, etc for each well. Further by selecting proper flow rate reduction, the flow distribution after plateau time to sustain the delivery is computed for each well.

  14. Optimising Gas Quenching Technology through Modelling of Heat Transfer

    Institute of Scientific and Technical Information of China (English)

    Florent Chaffotte; Linda L(e)fevre; Didier Domergue; Aymeric Goldsteinas; Xavier Doussot; Qingfei Zhang

    2004-01-01

    Gas Quenching represents an environmentally friendly alternative to more commonly-used oil quenching. Yet,the performances of this technology remain limited in terms of cooling rates reached compared to oil quenching. Distortion and process homogeneity also have to be controlled carefully. The efficiency of the gas quenching process fully depends on the heat transfer between the gas and the quenched parts. The goal of this study is the optimisation of the gas quenching process efficiency through a better understanding of the heat transfer phenomena involved. The study has been performed with modelling means and validated by an experimental approach. The configuration of the gas flow has a major influence on the heat transfer phenomena between the gas and the parts. The fluid dynamics modelling approach performed in this study allows to optimise the heat transfer phenomena. New gas quenching processes allowing enhanced gas quenching performance through higher cooling rates can be thereby identified. The new solutions have been validated in experimental and industrial conditions. Results obtained allow to expect significant improvement of high pressure gas quenching technology.

  15. Optimising Gas Quenching Technology through Modelling of Heat Transfer

    Institute of Scientific and Technical Information of China (English)

    FiorentChaffotte; LindaLefevre; DidierDomergue; AymericGoidsteinas; XavierDoussot; QingfeiZhang

    2004-01-01

    Gas Quenching represents an environmentally friendly alternative to more commonly-used oil quenching. Yet,the performances of this technology remain limited in terms of cooling rates reached compared to oil quenching. Distortion and process homogeneity also have to be controlled carefully. The efficiency of the gas quenching process fully depends on the heat transfer between the gas and the quenched parts. The goal of this study is the optimisation of the gas quenching process efficiency through a better understanding of the heat transfer phenomena involved. The study has been performed with modelling means and validated by an experimental approach. ThE configuration of the gas flow has a major influence on the heat transfer phenomena between the gas and the parts. The fluid dynamics modelling approach performed in this study allows to optimise the heat transfer phenomena. New gas quenching processes allowing enhanced gas quenching performance through higher cooling rates can be thereby identified. The new solutions have been validated in experimental and industrial conditions. Results obtained allow to expect significant improvement of high pressure gas quenching technology.

  16. $\\gamma-$ray line signal in the 750 GeV-diphoton-excess-motivated gravity mediator dark matter model

    CERN Document Server

    Zhang, Cun; Feng, Lei; Fan, Yi-Zhong; Ren, Zhong-Zhou

    2016-01-01

    The 750 GeV diphoton excess observed by LHC may indicate the existence of a new mediator particle. If intrinsic it will be a great revolution of the Standard Model and a new spin-0 or 2 particle should be included. In this work we discuss the spin-2 mediator model in which the new particle interacts with dark matter particles. The dark matter particles can annihilate into two photons and give rise to gamma-ray line signal that is widely believed to be the smoking-gun signature in the dark matter indirect detection. Then we scan the parameter space with the constraints of LHC data, dark matter relic density and gamma ray line search and finally obtain the allowed regions. In our scenario the rest mass of the dark matter particles is larger than 330 GeV and the cross section of annihilation into two $\\gamma$-rays is expected to be in the range of $\\sim 10^{-31}-10^{-27}~{\\rm cm^{3}~s^{-1}}$, which can be (partly) probed by the ongoing and upcoming space or ground-based gamma-ray experiments.

  17. Computational modeling of Krypton Gas Puffs on Z

    Science.gov (United States)

    Jennings, Christopher

    2014-10-01

    Large diameter multi-shell gas puffs rapidly imploded by high current (~20 MA, ~100 ns) on the Z generator of Sandia National Laboratories are able to produce high-intensity K-shell radiation. Experiments are currently underway to produce Krypton K-shell emission at ~13 keV, from double annular shell gas puffs imploded from a 12 cm diameter onto a central gas jet. Efficiently radiating at these high photon energies represents a significant challenge which necessitates the careful design and optimization of the gas distribution. To facilitate this we hydro-dynamically model the gas flow out of the nozzle, before imploding that mass distribution using a 3-dimensional resistive, radiative MHD code (GORGON). We present details of how modeled gas profiles are validated against 2-dimensional interferometric measurements of the initial gas distribution, and MHD calculations are validated against power, yield, spectral and imaging diagnostics of the experiments. This approach has enabled us to iterate between modeling the implosion and gas flow from the nozzle to optimize radiative output from this combined system. Guided by our implosion calculations we have designed and implemented gas profiles that help mitigate disruption from Magneto-Rayleigh-Taylor implosion instabilities, while preserving sufficient kinetic energy to thermalize to the high temperatures required for K-shell emission. Predicted increases in yield from introducing a relief feature into the inner gas nozzle to create a radially increasing density distribution were recovered in experiment. K-shell yield is predicted to further increase by the introduction of an on-axis gas jet, although the mass of this jet must be carefully selected with respect to the delivered current to avoid reducing the yield. For Kr gas puffs the predicted K-shell yield increase from addition of a light central jet was realized in the experiments, considerably increasing the yield over previous results. Further confidence in our

  18. Revisions to the hydrogen gas generation computer model

    Energy Technology Data Exchange (ETDEWEB)

    Jerrell, J.W.

    1992-08-31

    Waste Management Technology has requested SRTC to maintain and extend a previously developed computer model, TRUGAS, which calculates hydrogen gas concentrations within the transuranic (TRU) waste drums. TRUGAS was written by Frank G. Smith using the BASIC language and is described in the report A Computer Model of gas Generation and Transport within TRU Waste Drums (DP- 1754). The computer model has been partially validated by yielding results similar to experimental data collected at SRL and LANL over a wide range of conditions. The model was created to provide the capability of predicting conditions that could potentially lead to the formation of flammable gas concentrations within drums, and to assess proposed drum venting methods. The model has served as a tool in determining how gas concentrations are affected by parameters such as filter vent sizes, waste composition, gas generation values, the number and types of enclosures, water instrusion into the drum, and curie loading. The success of the TRUGAS model has prompted an interest in the program`s maintenance and enhancement. Experimental data continues to be collected at various sites on such parameters as permeability values, packaging arrangements, filter designs, and waste contents. Information provided by this data is used to improve the accuracy of the model`s predictions. Also, several modifications to the model have been made to enlarge the scope of problems which can be analyzed. For instance, the model has been used to calculate hydrogen concentrations inside steel cabinets containing retired glove boxes (WSRC-RP-89-762). The revised TRUGAS computer model, H2GAS, is described in this report. This report summarizes all modifications made to the TRUGAS computer model and provides documentation useful for making future updates to H2GAS.

  19. Modeling Hydrates and the Gas Hydrate Markup Language

    Directory of Open Access Journals (Sweden)

    Weihua Wang

    2007-06-01

    Full Text Available Natural gas hydrates, as an important potential fuels, flow assurance hazards, and possible factors initiating the submarine geo-hazard and global climate change, have attracted the interest of scientists all over the world. After two centuries of hydrate research, a great amount of scientific data on gas hydrates has been accumulated. Therefore the means to manage, share, and exchange these data have become an urgent task. At present, metadata (Markup Language is recognized as one of the most efficient ways to facilitate data management, storage, integration, exchange, discovery and retrieval. Therefore the CODATA Gas Hydrate Data Task Group proposed and specified Gas Hydrate Markup Language (GHML as an extensible conceptual metadata model to characterize the features of data on gas hydrate. This article introduces the details of modeling portion of GHML.

  20. Effects of gas types and models on optimized gas fuelling station reservoir's pressure

    Directory of Open Access Journals (Sweden)

    M. Farzaneh-Gord

    2013-06-01

    Full Text Available There are similar algorithms and infrastructure for storing gas fuels at CNG (Compressed Natural Gas and CHG (Compressed Hydrogen Gas fuelling stations. In these stations, the fuels are usually stored in the cascade storage system to utilize the stations more efficiently. The cascade storage system generally divides into three reservoirs, commonly termed low, medium and high-pressure reservoirs. The pressures within these reservoirs have huge effects on performance of the stations. In the current study, based on the laws of thermodynamics, conservation of mass and real/ideal gas assumptions, a theoretical analysis has been constructed to study the effects of gas types and models on performance of the stations. It is intended to determine the optimized reservoir pressures for these stations. The results reveal that the optimized pressure differs between the gas types. For ideal and real gas models in both stations (CNG and CHG, the optimized non-dimensional low pressure-reservoir pressure is found to be 0.22. The optimized non-dimensional medium-pressure reservoir pressure is the same for the stations, and equal to 0.58.

  1. Thermodynamic Modeling of Natural Gas Systems Containing Water

    DEFF Research Database (Denmark)

    Karakatsani, Eirini K.; Kontogeorgis, Georgios M.

    2013-01-01

    with a heavy phase were previously obtained using cubic plus association (CPA) coupled with a solid phase model in the case of hydrates, for the binary systems of water–methane and water–nitrogen and a few natural gas mixtures. In this work, CPA is being validated against new experimental data, both water...... content and phase equilibrium data, and solid model parameters are being estimated for four natural gas main components (methane, ethane, propane, and carbon dioxide). Different tests for the solid model parameters are reported, including vapor-hydrate-equilibria (VHE) and liquid-hydrate-equilibria (LHE......As the need for dew point specifications remains very urgent in the natural gas industry, the development of accurate thermodynamic models, which will match experimental data and will allow reliable extrapolations, is needed. Accurate predictions of the gas phase water content in equilibrium...

  2. Viscous dissipative Chaplygin gas dominated homogenous and isotropic cosmological models

    CERN Document Server

    Pun, C S J; Mak, M K; Kovács, Z; Szabó, G M; Harko, T

    2008-01-01

    The generalized Chaplygin gas, which interpolates between a high density relativistic era and a non-relativistic matter phase, is a popular dark energy candidate. We consider a generalization of the Chaplygin gas model, by assuming the presence of a bulk viscous type dissipative term in the effective thermodynamic pressure of the gas. The dissipative effects are described by using the truncated Israel-Stewart model, with the bulk viscosity coefficient and the relaxation time functions of the energy density only. The corresponding cosmological dynamics of the bulk viscous Chaplygin gas dominated universe is considered in detail for a flat homogeneous isotropic Friedmann-Robertson-Walker geometry. For different values of the model parameters we consider the evolution of the cosmological parameters (scale factor, energy density, Hubble function, deceleration parameter and luminosity distance, respectively), by using both analytical and numerical methods. In the large time limit the model describes an acceleratin...

  3. Revisions to the hydrogen gas generation computer model

    Energy Technology Data Exchange (ETDEWEB)

    Jerrell, J.W.

    1992-08-31

    Waste Management Technology has requested SRTC to maintain and extend a previously developed computer model, TRUGAS, which calculates hydrogen gas concentrations within the transuranic (TRU) waste drums. TRUGAS was written by Frank G. Smith using the BASIC language and is described in the report A Computer Model of gas Generation and Transport within TRU Waste Drums (DP- 1754). The computer model has been partially validated by yielding results similar to experimental data collected at SRL and LANL over a wide range of conditions. The model was created to provide the capability of predicting conditions that could potentially lead to the formation of flammable gas concentrations within drums, and to assess proposed drum venting methods. The model has served as a tool in determining how gas concentrations are affected by parameters such as filter vent sizes, waste composition, gas generation values, the number and types of enclosures, water instrusion into the drum, and curie loading. The success of the TRUGAS model has prompted an interest in the program's maintenance and enhancement. Experimental data continues to be collected at various sites on such parameters as permeability values, packaging arrangements, filter designs, and waste contents. Information provided by this data is used to improve the accuracy of the model's predictions. Also, several modifications to the model have been made to enlarge the scope of problems which can be analyzed. For instance, the model has been used to calculate hydrogen concentrations inside steel cabinets containing retired glove boxes (WSRC-RP-89-762). The revised TRUGAS computer model, H2GAS, is described in this report. This report summarizes all modifications made to the TRUGAS computer model and provides documentation useful for making future updates to H2GAS.

  4. Phase space analysis of some interacting Chaplygin gas models

    Energy Technology Data Exchange (ETDEWEB)

    Khurshudyan, M. [Academy of Sciences of Armenia, Institute for Physical Research, Ashtarak (Armenia); Tomsk State University of Control Systems and Radioelectronics, Laboratory for Theoretical Cosmology, Tomsk (Russian Federation); Tomsk State Pedagogical University, Department of Theoretical Physics, Tomsk (Russian Federation); Myrzakulov, R. [Eurasian National University, Eurasian International Center for Theoretical Physics, Astana (Kazakhstan)

    2017-02-15

    In this paper we discuss a phase space analysis of various interacting Chaplygin gas models in general relativity. Linear and nonlinear sign changeable interactions are considered. For each case appropriate late time attractors of field equations are found. The Chaplygin gas is one of the dark fluids actively considered in modern cosmology due to the fact that it is a joint model of dark energy and dark matter. (orig.)

  5. Reliability modelling - PETROBRAS 2010 integrated gas supply chain

    Energy Technology Data Exchange (ETDEWEB)

    Faertes, Denise; Heil, Luciana; Saker, Leonardo; Vieira, Flavia; Risi, Francisco; Domingues, Joaquim; Alvarenga, Tobias; Carvalho, Eduardo; Mussel, Patricia

    2010-09-15

    The purpose of this paper is to present the innovative reliability modeling of Petrobras 2010 integrated gas supply chain. The model represents a challenge in terms of complexity and software robustness. It was jointly developed by PETROBRAS Gas and Power Department and Det Norske Veritas. It was carried out with the objective of evaluating security of supply of 2010 gas network design that was conceived to connect Brazilian Northeast and Southeast regions. To provide best in class analysis, state of the art software was used to quantify the availability and the efficiency of the overall network and its individual components.

  6. Gas Atomization of Aluminium Melts: Comparison of Analytical Models

    Directory of Open Access Journals (Sweden)

    Georgios Antipas

    2012-06-01

    Full Text Available A number of analytical models predicting the size distribution of particles during atomization of Al-based alloys by N2, He and Ar gases were compared. Simulations of liquid break up in a close coupled atomizer revealed that the finer particles are located near the center of the spray cone. Increasing gas injection pressures led to an overall reduction of particle diameters and caused a migration of the larger powder particles towards the outer boundary of the flow. At sufficiently high gas pressures the spray became monodisperse. The models also indicated that there is a minimum achievable mean diameter for any melt/gas system.

  7. Sensitivity analysis of the fission gas behavior model in BISON.

    Energy Technology Data Exchange (ETDEWEB)

    Swiler, Laura Painton; Pastore, Giovanni; Perez, Danielle; Williamson, Richard

    2013-05-01

    This report summarizes the result of a NEAMS project focused on sensitivity analysis of a new model for the fission gas behavior (release and swelling) in the BISON fuel performance code of Idaho National Laboratory. Using the new model in BISON, the sensitivity of the calculated fission gas release and swelling to the involved parameters and the associated uncertainties is investigated. The study results in a quantitative assessment of the role of intrinsic uncertainties in the analysis of fission gas behavior in nuclear fuel.

  8. Validation of spectral gas radiation models under oxyfuel conditions

    Energy Technology Data Exchange (ETDEWEB)

    Becher, Johann Valentin

    2013-05-15

    Combustion of hydrocarbon fuels with pure oxygen results in a different flue gas composition than combustion with air. Standard computational-fluid-dynamics (CFD) spectral gas radiation models for air combustion are therefore out of their validity range in oxyfuel combustion. This thesis provides a common spectral basis for the validation of new spectral models. A literature review about fundamental gas radiation theory, spectral modeling and experimental methods provides the reader with a basic understanding of the topic. In the first results section, this thesis validates detailed spectral models with high resolution spectral measurements in a gas cell with the aim of recommending one model as the best benchmark model. In the second results section, spectral measurements from a turbulent natural gas flame - as an example for a technical combustion process - are compared to simulated spectra based on measured gas atmospheres. The third results section compares simplified spectral models to the benchmark model recommended in the first results section and gives a ranking of the proposed models based on their accuracy. A concluding section gives recommendations for the selection and further development of simplified spectral radiation models. Gas cell transmissivity spectra in the spectral range of 2.4 - 5.4 {mu}m of water vapor and carbon dioxide in the temperature range from 727 C to 1500 C and at different concentrations were compared in the first results section at a nominal resolution of 32 cm{sup -1} to line-by-line models from different databases, two statistical-narrow-band models and the exponential-wide-band model. The two statistical-narrow-band models EM2C and RADCAL showed good agreement with a maximal band transmissivity deviation of 3 %. The exponential-wide-band model showed a deviation of 6 %. The new line-by-line database HITEMP2010 had the lowest band transmissivity deviation of 2.2% and was therefore recommended as a reference model for the

  9. Modeling Data with Excess Zeros and Measurement Error: Application to Evaluating Relationships between Episodically Consumed Foods and Health Outcomes

    KAUST Repository

    Kipnis, Victor

    2009-03-03

    Dietary assessment of episodically consumed foods gives rise to nonnegative data that have excess zeros and measurement error. Tooze et al. (2006, Journal of the American Dietetic Association 106, 1575-1587) describe a general statistical approach (National Cancer Institute method) for modeling such food intakes reported on two or more 24-hour recalls (24HRs) and demonstrate its use to estimate the distribution of the food\\'s usual intake in the general population. In this article, we propose an extension of this method to predict individual usual intake of such foods and to evaluate the relationships of usual intakes with health outcomes. Following the regression calibration approach for measurement error correction, individual usual intake is generally predicted as the conditional mean intake given 24HR-reported intake and other covariates in the health model. One feature of the proposed method is that additional covariates potentially related to usual intake may be used to increase the precision of estimates of usual intake and of diet-health outcome associations. Applying the method to data from the Eating at America\\'s Table Study, we quantify the increased precision obtained from including reported frequency of intake on a food frequency questionnaire (FFQ) as a covariate in the calibration model. We then demonstrate the method in evaluating the linear relationship between log blood mercury levels and fish intake in women by using data from the National Health and Nutrition Examination Survey, and show increased precision when including the FFQ information. Finally, we present simulation results evaluating the performance of the proposed method in this context.

  10. A modified simulated annealing algorithm and an excessive area model for floorplanning using fixed-outline constraints

    Institute of Scientific and Technical Information of China (English)

    De-xuan ZOU; Gai-ge WANG; Gai PAN; Hong-wei QI

    2016-01-01

    Outline-free floorplanning focuses on area and wirelength reductions, which are usually meaningless, since they can hardly satisfy modern design requirements. We concentrate on a more difficult and useful issue, fixed-outline floorplanning. This issue imposes fixed-outline constraints on the outline-free floorplanning, making the physical design more interesting and chal-lenging. The contributions of this paper are primarily twofold. First, a modified simulated annealing (MSA) algorithm is proposed. In the beginning of the evolutionary process, a new attenuation formula is used to decrease the temperature slowly, to enhance MSA’s global searching capacity. After a period of time, the traditional attenuation formula is employed to decrease the temper-ature rapidly, to maintain MSA’s local searching capacity. Second, an excessive area model is designed to guide MSA to find feasible solutions readily. This can save much time for refining feasible solutions. Additionally, B*-tree representation is known as a very useful method for characterizing floorplanning. Therefore, it is employed to perform a perturbing operation for MSA. Finally, six groups of benchmark instances with different dead spaces and aspect ratios—circuits n10, n30, n50, n100, n200, and n300—are chosen to demonstrate the efficiency of our proposed method on fixed-outline floorplanning. Compared to several existing methods, the proposed method is more efficient in obtaining desirable objective function values associated with the chip area, wirelength, and fixed-outline constraints.

  11. Methane excess production in oxygen-rich polar water and a model of cellular conditions for this paradox

    Science.gov (United States)

    Damm, E.; Thoms, S.; Beszczynska-Möller, A.; Nöthig, E. M.; Kattner, G.

    2015-09-01

    Summer sea ice cover in the Arctic Ocean has undergone a reduction in the last decade exposing the sea surface to unforeseen environmental changes. Melting sea ice increases water stratification and induces nutrient limitation, which is also known to play a crucial role in methane formation in oxygenated surface water. We report on an excess of methane in the marginal ice zone in the western Fram Strait. Our study is based on measurements of oxygen, methane, DMSP, nitrate and phosphate concentrations as well as on phytoplankton composition and light transmission, conducted along the 79°N oceanographic transect, in the western part of the Fram Strait and in Northeast Water Polynya region off Greenland. Between the eastern Fram Strait, where Atlantic water enters from the south and the western Fram Strait, where Polar water enters from the north, different nutrient limitations occurred and consequently different bloom conditions were established. Ongoing sea ice melting enhances the environmental differences between both water masses and initiates regenerated production in the western Fram Strait. We show that in this region methane is in situ produced while DMSP (dimethylsulfoniopropionate) released from sea ice may serve as a precursor for the methane formation. The methane production occured despite high oxygen concentrations in this water masses. As the metabolic activity (respiration) of unicellular organisms explains the presence of anaerobic conditions in the cellular environment we present a theoretical model which explains the maintenance of anaerobic conditions for methane formation inside bacterial cells, despite enhanced oxygen concentrations in the environment.

  12. Static and dynamic modelling of gas turbines in advanced cycles

    Energy Technology Data Exchange (ETDEWEB)

    Gustafsson, Jan-Olof

    1998-12-01

    Gas turbines have been in operation for at least 50 years. The engine is used for propulsion of aircraft and high speed ships. It is used for power production in remote locations and for peak load and emergency situations. Gas turbines have been used in combined cycles for 20 to 30 years. Highly efficient power plants based on gas turbines are a competitive option for the power industry today. The thermal efficiency of the simple cycle gas turbine has increased due to higher turbine inlet temperatures and improved compressor and expander designs. Equally important are the improved cycles in which the gas turbine operates. One example is the combined cycle that uses steam for turbine cooling. Steam is extracted from the bottoming cycle, then used as airfoil coolant in a closed loop and returned to the bottoming cycle. The Evaporative Gas Turbine (EvGT), also known as the Humid Air Turbine (HAT), is another advanced cycle. A mixture of air and water vapour is used as working media. Air from the compressor outlet is humidified and then preheated in a recuperator prior to combustion. The static and dynamic performance is changed when the gas turbine is introduced in an evaporative cycle. The cycle is gaining in popularity, but so far it has not been demonstrated. A Swedish joint program to develop the cycle has been in operation since 1993. As part of the program, a small pilot plant is being erected at the Lund Institute of Technology (LTH). The plant is based on a 600 kW gas turbine, and demonstration of the EvGT cycle started autumn 1998 and will continue, in the present phase, for one year. This thesis presents static and dynamic models for traditional gas turbine components, such as, the compressor, combustor, expander and recuperator. A static model for the humidifier is presented, based on common knowledge for atmospheric humidification. All models were developed for the pilot plant at LTH with the objective to support evaluation of the process and individual

  13. 5-Lump kinetic model for gas oil catalytic cracking

    Energy Technology Data Exchange (ETDEWEB)

    Ancheyta-Juarez, Jorge; Aguilar-Rodriguez, Enrique [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, Mexico 07730 DF (Mexico); Lopez-Isunza, Felipe [Universidad Autonoma Metropolitana-Iztapalapa, Mexico 09340 DF (Mexico)

    1999-02-22

    A new 5-lump kinetic model is proposed to describe the gas oil catalytic cracking (FCC) process. The model contains eight kinetic constants, including one for catalyst deactivation, taking into account LPG (combined C{sub 3}-C{sub 4}), dry gas (C{sub 2} and lighter) and coke yields separately from other lumps (unconverted gas oil and gasoline). Apparent activation energies were determined from experiments obtained in a microactivity reactor (MAT) at temperatures: 480C, 500C and 520C; for a catalyst-to-oil ratio of 5 using vacuum gas oil and equilibrium catalyst, both recovered from an industrial FCC unit. Product yields predicted by this model show good agreement with experimental data

  14. Experimental Grey Box Model Identification of an Active Gas Bearing

    DEFF Research Database (Denmark)

    Theisen, Lukas Roy Svane; Pierart Vásquez, Fabián Gonzalo; Niemann, Hans Henrik;

    2014-01-01

    in a dynamic model of an active gas bearing and subsequent control loop design. A grey box model is determined based on experiments where piezo actuated valves are used to perturb the journal and hence excite the rotor-bearing system. Such modelling from actuator to output is shown to effciently support...

  15. Multispecies Decompression Model Using Asymmetrical Gas Kinetics

    Science.gov (United States)

    2003-01-01

    7, Pi is the partial pressures of the inspired gas T’, Pamb is the ambient pressure, Pthr is the estimated threshold parameter, and asym is the...risk for a given compartment was defined to be the supersaturation above a threshold ( Pthr ): risk = •gain P Pa,,trj, (4) where gain is a scale factor...The parameters for which the deltas were estimated were: 1. -, time constants for N2 and 02, 2. Pthr , the threshold pressure above which risk

  16. Diffusive description of lattice gas models

    DEFF Research Database (Denmark)

    Fiig, T.; Jensen, H.J.

    1993-01-01

    in time. We have numerically investigated the power spectrum of the density fluctuations, the lifetime distribution, and the spatial correlation function. We discuss the appropriate Langevin-like diffusion equation which can reproduce our numerical findings. Our conclusion is that the deterministic...... lattice gases are described by a diffusion equation without any bulk noise. The open lattice gas exhibits a crossover behavior as the probability for introducing particles at the edge of the system becomes small. The power spectrum changes from a 1/f to a 1/f2 spectrum. The diffusive description, proven...

  17. A GIS-based Model for Natural Gas Data Conversion

    Science.gov (United States)

    Bitik, E.; Seker, D. Z.; Denli, H. H.

    2014-12-01

    In Turkey gas utility sector has undergone major changes in terms of increased competition between gas providers, efforts in improving services, and applying new technological solutions. This paper discusses the challenges met by gas companies to switch from long workflows of gas distribution, sales and maintenance into IT driven efficient management of complex information both spatially and non-spatially. The aim of this study is migration of all gas data and information into a GIS environment in order to manage and operate all infrastructure investments with a Utility Management System. All data conversion model for migration was designed and tested during the study. A flowchart is formed to transfer the old data layers to the new structure based on geodatabase.

  18. Empirical Modeling of Plant Gas Fluxes in Controlled Environments

    Science.gov (United States)

    Cornett, Jessie David

    1994-01-01

    As humans extend their reach beyond the earth, bioregenerative life support systems must replace the resupply and physical/chemical systems now used. The Controlled Ecological Life Support System (CELSS) will utilize plants to recycle the carbon dioxide (CO2) and excrement produced by humans and return oxygen (O2), purified water and food. CELSS design requires knowledge of gas flux levels for net photosynthesis (PS(sub n)), dark respiration (R(sub d)) and evapotranspiration (ET). Full season gas flux data regarding these processes for wheat (Triticum aestivum), soybean (Glycine max) and rice (Oryza sativa) from published sources were used to develop empirical models. Univariate models relating crop age (days after planting) and gas flux were fit by simple regression. Models are either high order (5th to 8th) or more complex polynomials whose curves describe crop development characteristics. The models provide good estimates of gas flux maxima, but are of limited utility. To broaden the applicability, data were transformed to dimensionless or correlation formats and, again, fit by regression. Polynomials, similar to those in the initial effort, were selected as the most appropriate models. These models indicate that, within a cultivar, gas flux patterns appear remarkably similar prior to maximum flux, but exhibit considerable variation beyond this point. This suggests that more broadly applicable models of plant gas flux are feasible, but univariate models defining gas flux as a function of crop age are too simplistic. Multivariate models using CO2 and crop age were fit for PS(sub n), and R(sub d) by multiple regression. In each case, the selected model is a subset of a full third order model with all possible interactions. These models are improvements over the univariate models because they incorporate more than the single factor, crop age, as the primary variable governing gas flux. They are still limited, however, by their reliance on the other environmental

  19. Low excess air operations of oil boilers

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, T.A.; Celebi, Y.; Litzke, Wai Lin [Brookhaven National Labs., Upton, NY (United States)

    1997-09-01

    To quantify the benefits which operation at very low excess air operation may have on heat exchanger fouling BNL has recently started a test project. The test allows simultaneous measurement of fouling rate, flue gas filterable soot, flue gas sulfuric acid content, and flue gas sulfur dioxide.

  20. Analysis of a model of fuel cell - gas turbine hybrid power system for enhanced energy efficiency

    Science.gov (United States)

    Calay, Rajnish K.; Mustafa, Mohamad Y.; Virk, Mohammad S.; Mustafa, Mahmoud F.

    2012-11-01

    A simple mathematical model to evaluate the performance of FC-GT hybrid system is presented in this paper. The model is used to analyse the influence of various parameters on the performance of a typical hybrid system, where excess heat rejected from the solid-oxide fuel cell stack is utilised to generate additional power through a gas turbine system and to provide heat energy for space heating. The model is based on thermodynamic analysis of various components of the plant and can be adapted for various configurations of the plant components. Because there are many parameters defining the efficiency and work output of the hybrid system, the technique is based on mathematical and graphical optimisation of various parameters; to obtain the maximum efficiency for a given plant configuration.

  1. Gas discharges modeling by Monte Carlo technique

    Directory of Open Access Journals (Sweden)

    Savić Marija

    2010-01-01

    Full Text Available The basic assumption of the Townsend theory - that ions produce secondary electrons - is valid only in a very narrow range of the reduced electric field E/N. In accordance with the revised Townsend theory that was suggested by Phelps and Petrović, secondary electrons are produced in collisions of ions, fast neutrals, metastable atoms or photons with the cathode, or in gas phase ionizations by fast neutrals. In this paper we tried to build up a Monte Carlo code that can be used to calculate secondary electron yields for different types of particles. The obtained results are in good agreement with the analytical results of Phelps and. Petrović [Plasma Sourc. Sci. Technol. 8 (1999 R1].

  2. The World gas model. A multi-period mixed complementarity model for the global natural gas market

    Energy Technology Data Exchange (ETDEWEB)

    Egging, Ruud [Dept of Civil and Environmental Engineering, University of Maryland, 1143 Glenn L. Martin Hall, College Park, MD 20742 (United States); Holz, Franziska [DIW Berlin, Mohrenstr. 58, 10117 Berlin (Germany); Gabriel, Steven A. [Dept of Civil and Environmental Engineering, University of Maryland, 1143 Glenn L. Martin Hall, College Park, MD 20742 (United States); DIW Berlin, Mohrenstr. 58, 10117 Berlin (Germany)

    2010-10-15

    We provide the description, mathematical formulation and illustrative results of the World Gas Model, a multi-period complementarity model for the global natural gas market with explicit consideration of market power in the upstream market. Market players include producers, traders, pipeline and storage operators, LNG (liquefied natural gas) liquefiers and regasifiers as well as marketers. The model data set contains more than 80 countries and regions and covers 98% of world wide natural gas production and consumption. We also include a detailed representation of cross-border natural gas pipelines and constraints imposed by long-term contracts in the LNG market. The model is calibrated to match production and consumption projections from the PRIMES [EC. European energy and transport: trends to 2030-update 2007. Brussels: European Commission; 2008] and POLES models [EC. World energy technology outlook - 2050 (WETO-H2). Brussels: European Commission; 2006] up to 2030. The results of our numerical simulations illustrate how the supply shares of pipeline and LNG in various regions in the world develop very differently over time. LNG will continue to play a major role in the Asian market, also for new importers like China and India. Europe will expand its pipeline import capacities benefiting from its relative proximity to major gas suppliers. (author)

  3. Model-based dynamic control and optimization of gas networks

    Energy Technology Data Exchange (ETDEWEB)

    Hofsten, Kai

    2001-07-01

    This work contributes to the research on control, optimization and simulation of gas transmission systems to support the dispatch personnel at gas control centres for the decision makings in the daily operation of the natural gas transportation systems. Different control and optimization strategies have been studied. The focus is on the operation of long distance natural gas transportation systems. Stationary optimization in conjunction with linear model predictive control using state space models is proposed for supply security, the control of quality parameters and minimization of transportation costs for networks offering transportation services. The result from the stationary optimization together with a reformulation of a simplified fluid flow model formulates a linear dynamic optimization model. This model is used in a finite time control and state constrained linear model predictive controller. The deviation from the control and the state reference determined from the stationary optimization is penalized quadratically. Because of the time varying status of infrastructure, the control space is also generally time varying. When the average load is expected to change considerably, a new stationary optimization is performed, giving a new state and control reference together with a new dynamic model that is used for both optimization and state estimation. Another proposed control strategy is a control and output constrained nonlinear model predictive controller for the operation of gas transmission systems. Here, the objective is also the security of the supply, quality control and minimization of transportation costs. An output vector is defined, which together with a control vector are both penalized quadratically from their respective references in the objective function. The nonlinear model predictive controller can be combined with a stationary optimization. At each sampling instant, a non convex nonlinear programming problem is solved giving a local minimum

  4. Estimating Predictive Variance for Statistical Gas Distribution Modelling

    Science.gov (United States)

    Lilienthal, Achim J.; Asadi, Sahar; Reggente, Matteo

    2009-05-01

    Recent publications in statistical gas distribution modelling have proposed algorithms that model mean and variance of a distribution. This paper argues that estimating the predictive concentration variance entails not only a gradual improvement but is rather a significant step to advance the field. This is, first, since the models much better fit the particular structure of gas distributions, which exhibit strong fluctuations with considerable spatial variations as a result of the intermittent character of gas dispersal. Second, because estimating the predictive variance allows to evaluate the model quality in terms of the data likelihood. This offers a solution to the problem of ground truth evaluation, which has always been a critical issue for gas distribution modelling. It also enables solid comparisons of different modelling approaches, and provides the means to learn meta parameters of the model, to determine when the model should be updated or re-initialised, or to suggest new measurement locations based on the current model. We also point out directions of related ongoing or potential future research work.

  5. The strong coupling Kondo lattice model as a Fermi gas

    CERN Document Server

    Östlund, S

    2007-01-01

    The strong coupling half-filled Kondo lattice model is an important example of a strongly interacting dense Fermi system for which conventional Fermi gas analysis has thus far failed. We remedy this by deriving an exact transformation that maps the model to a dilute gas of weakly interacting electron and hole quasiparticles that can then be analyzed by conventional dilute Fermi gas methods. The quasiparticle vacuum is a singlet Mott insulator for which the quasiparticle dynamics are simple. Since the transformation is exact, the electron spectral weight sum rules are obeyed exactly. Subtleties in understanding the behavior of electrons in the singlet Mott insulator can be reduced to a fairly complicated but precise relation between quasiparticles and bare electrons. The theory of free quasiparticles can be interpreted as an exactly solvable model for a singlet Mott insulator, providing an exact model in which to explore the strong coupling regime of a singlet Kondo insulator.

  6. Dynamics of warm Chaplygin gas inflationary models with quartic potential

    Energy Technology Data Exchange (ETDEWEB)

    Jawad, Abdul; Rani, Shamaila [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan); Butt, Sadaf [Lahore Leads University, Department of Mathematics, Lahore (Pakistan); Kinnaird College for Women, Department of Mathematics, Lahore (Pakistan)

    2016-05-15

    Warm inflationary universe models in the context of the generalized Chaplygin gas, the modified Chaplygin gas, and the generalized cosmic Chaplygin gas are being studied. The dissipative coefficient of the form Γ ∝ T, and the weak and the strong dissipative regimes are being considered. We use the quartic potential, (λ{sub *}φ{sup 4})/(4), which is ruled out by current data in cold inflation but in our models by analysis it is seen to be in agreement with the WMAP9 and the latest Planck data. In these scenarios, the power spectrum, the spectral index, and the tensor-to-scalar ratio are being examined in the slow-roll approximation. We show the dependence of the tensor-scalar ratio r on the spectral index n{sub s} and observe that the range of the tensor-scalar ratio is r < 0.05 in the generalized Chaplygin gas, r < 0.15 in the modified Chaplygin gas, and r < 0.12 in the generalized cosmic Chaplygin gas models. Our results are in agreement with recent observational data like WMAP9 and the latest Planck data. (orig.)

  7. A continuum model for metabolic gas exchange in pear fruit.

    Directory of Open Access Journals (Sweden)

    Q Tri Ho

    2008-03-01

    Full Text Available Exchange of O(2 and CO(2 of plants with their environment is essential for metabolic processes such as photosynthesis and respiration. In some fruits such as pears, which are typically stored under a controlled atmosphere with reduced O(2 and increased CO(2 levels to extend their commercial storage life, anoxia may occur, eventually leading to physiological disorders. In this manuscript we have developed a mathematical model to predict the internal gas concentrations, including permeation, diffusion, and respiration and fermentation kinetics. Pear fruit has been selected as a case study. The model has been used to perform in silico experiments to evaluate the effect of, for example, fruit size or ambient gas concentration on internal O(2 and CO(2 levels. The model incorporates the actual shape of the fruit and was solved using fluid dynamics software. Environmental conditions such as temperature and gas composition have a large effect on the internal distribution of oxygen and carbon dioxide in fruit. Also, the fruit size has a considerable effect on local metabolic gas concentrations; hence, depending on the size, local anaerobic conditions may result, which eventually may lead to physiological disorders. The model developed in this manuscript is to our knowledge the most comprehensive model to date to simulate gas exchange in plant tissue. It can be used to evaluate the effect of environmental stresses on fruit via in silico experiments and may lead to commercial applications involving long-term storage of fruit under controlled atmospheres.

  8. Crossing the Phantom divide line in the Chaplygin gas model

    CERN Document Server

    Sadjadi, H Mohseni

    2009-01-01

    The role of the interaction in crossing the phantom divide line in the Chaplygin gas model is discussed. We obtain some general properties of the interactions that allow the model to arrive at the phantom divide line. We show that these properties put some conditions on the ratio of dark matter to dark energy density.

  9. The dark connection between the EGRET excess of diffuse Galactic gamma rays, the Canis Major dwarf, the Monoceros ring, the INTEGRAL 511 keV annihilation line, the gas flaring and the Galactic rotation curve

    CERN Document Server

    de Boer, Wim

    2007-01-01

    The EGRET excess of diffuse Galactic gamma rays shows all the key features of dark matter annihilation (DMA) for a WIMP mass in the range 50-100 GeV, especially the distribution of the excess is compatible with a standard halo profile with some additional ringlike substructures at 4 and 13 kpc from the Galactic centre. These substructures coincide with the gravitational potential well expected from the ring of dust at 4 kpc and the tidal stream of dark matter from the Canis Major satellite galaxy at 13 kpc, as deduced from N-body simulations fitting to the Monoceros ring of stars. Strong independent support for this substructure is given by the gas flaring in our Galaxy. The gamma rays from DMA are originating predominantly from the hadronization of mono-energetic quarks, which should produce also a small, but known fraction of protons and antiprotons. Bergstrom et al. an antiproton flux far above the observed antiproton flux and they conclude that the DMA interpretation of the EGRET excess can therefore be e...

  10. Modeling of neutral gas dynamics in high-density plasmas

    Science.gov (United States)

    Canupp, Patrick Wellington

    This thesis describes a physical model of chemically reactive neutral gas flow and discusses numerical solutions of this model for the flow in an inductively coupled plasma etch reactor. To obtain these solutions, this research develops an efficient, implicit numerical method. As a result of the enhanced numerical stability of the scheme, large time steps advance the solution from initial conditions to a final steady state in fewer iterations and with less computational expense than simpler explicit methods. This method would incorporate suitably as a module in currently existing large scale plasma simulation tools. In order to demonstrate the accuracy of the numerical technique, this thesis presents results from two simulations of flows that possess theoretical solutions. The first case is the inviscid flow of a gas through a converging nozzle. A comparison of the numerical solution to isentropic flow theory shows that the numerical technique capably captures the essential flow features of this environment. The second case is the Couette flow of a gas between two parallel plates. The simulation results compare well with the exact solution for this flow. After establishing the accuracy of the numerical technique, this thesis discusses results for the flow of chemically reactive gases in a chlorine plasma etch reactor. This research examines the influence of the plasma on the neutral gas and the dynamics exhibited by the neutral gas in the reactor. This research finds that the neutral gas temperature strongly depends on the rate at which inelastic, electron-impact dissociation reactions occur and on atomic chlorine wall recombination rates. Additionally, the neutral gas Aow in the reactor includes a significant mass flux of etch product from the wafer surface. Resolution of these effects is useful for neutral gas simulation. Finally, this thesis demonstrates that continuum fluid models provide reasonable accuracy for these low pressure reactor flows due to the fact

  11. Modeling Propagation of Gas Path Damage

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper describes how damage propagation can be tracked and modeled for a range of fault modes in some modules of commercial high bypass aircraft engines. To that...

  12. Environmental control implications of generating electric power from coal. 1977 technology status report. Appendix D. Assessment of NO/sub x/ control technology for coal fired utility boilers. [Low-excess-air, staged combustion, flu gas recirculation and burner design

    Energy Technology Data Exchange (ETDEWEB)

    1977-12-01

    An NOx control technology assessment study was conducted to examine the effectiveness of low-excess-air firing, staged combustion, flue gas recirculation, and current burner/boiler designs as applied to coal-fired utility boilers. Significant variations in NOx emissions exist with boiler type, firing method, and coal type, but a relative comparison of emissions control performance, cost, and operational considerations is presented for each method. The study emphasized the numerous operational factors that are of major importance to the user in selecting and implementing a combustion modification technique. Staged combustion and low-excess-air operation were identified as the most cost-effective methods for existing units. Close control of local air/fuel ratios and rigorous combustion equipment maintenance are essential to the success of both methods. Flue gas recirculation is relatively ineffective and has the added concern of tube erosion. More research is needed to resolve potential corrosion concerns with low-NOx operating modes. Low-NOx burners in conjunction with a compartmentalized windbox are capable of meeting a 0.6-lb/million Btu emission level on new units. Advanced burner designs are being developed to meet research emission goals of approximately 0.25 lb/MBtu.

  13. Langasite surface acoustic wave gas sensors: modeling and verification

    Energy Technology Data Exchange (ETDEWEB)

    Peng Zheng,; Greve, D. W.; Oppenheim, I. J.

    2013-03-01

    We report finite element simulations of the effect of conductive sensing layers on the surface wave velocity of langasite substrates. The simulations include both the mechanical and electrical influences of the conducting sensing layer. We show that three-dimensional simulations are necessary because of the out-of-plane displacements of the commonly used (0, 138.5, 26.7) Euler angle. Measurements of the transducer input admittance in reflective delay-line devices yield a value for the electromechanical coupling coefficient that is in good agreement with the three-dimensional simulations on bare langasite substrate. The input admittance measurements also show evidence of excitation of an additional wave mode and excess loss due to the finger resistance. The results of these simulations and measurements will be useful in the design of surface acoustic wave gas sensors.

  14. Langasite Surface Acoustic Wave Gas Sensors: Modeling and Verification

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Peng; Greve, David W; Oppenheim, Irving J

    2013-01-01

    We report finite element simulations of the effect of conductive sensing layers on the surface wave velocity of langasite substrates. The simulations include both the mechanical and electrical influences of the conducting sensing layer. We show that three-dimensional simulations are necessary because of the out-of-plane displacements of the commonly used (0, 138.5, 26.7) Euler angle. Measurements of the transducer input admittance in reflective delay-line devices yield a value for the electromechanical coupling coefficient that is in good agreement with the three-dimensional simulations on bare langasite substrate. The input admittance measurements also show evidence of excitation of an additional wave mode and excess loss due to the finger resistance. The results of these simulations and measurements will be useful in the design of surface acoustic wave gas sensors.

  15. Potential biodefense model applications for portable chlorine dioxide gas production.

    Science.gov (United States)

    Stubblefield, Jeannie M; Newsome, Anthony L

    2015-01-01

    Development of decontamination methods and strategies to address potential infectious disease outbreaks and bioterrorism events are pertinent to this nation's biodefense strategies and general biosecurity. Chlorine dioxide (ClO2) gas has a history of use as a decontamination agent in response to an act of bioterrorism. However, the more widespread use of ClO2 gas to meet current and unforeseen decontamination needs has been hampered because the gas is too unstable for shipment and must be prepared at the application site. Newer technology allows for easy, onsite gas generation without the need for dedicated equipment, electricity, water, or personnel with advanced training. In a laboratory model system, 2 unique applications (personal protective equipment [PPE] and animal skin) were investigated in the context of potential development of decontamination protocols. Such protocols could serve to reduce human exposure to bacteria in a decontamination response effort. Chlorine dioxide gas was capable of reducing (2-7 logs of vegetative and spore-forming bacteria), and in some instances eliminating, culturable bacteria from difficult to clean areas on PPE facepieces. The gas was effective in eliminating naturally occurring bacteria on animal skin and also on skin inoculated with Bacillus spores. The culturable bacteria, including Bacillus spores, were eliminated in a time- and dose-dependent manner. Results of these studies suggested portable, easily used ClO2 gas generation systems have excellent potential for protocol development to contribute to biodefense strategies and decontamination responses to infectious disease outbreaks or other biothreat events.

  16. An Equilibrium-Based Model of Gas Reaction and Detonation

    Energy Technology Data Exchange (ETDEWEB)

    Trowbridge, L.D.

    2000-04-01

    During gaseous diffusion plant operations, conditions leading to the formation of flammable gas mixtures may occasionally arise. Currently, these could consist of the evaporative coolant CFC-114 and fluorinating agents such as F2 and ClF3. Replacement of CFC-114 with a non-ozone-depleting substitute is planned. Consequently, in the future, the substitute coolant must also be considered as a potential fuel in flammable gas mixtures. Two questions of practical interest arise: (1) can a particular mixture sustain and propagate a flame if ignited, and (2) what is the maximum pressure that can be generated by the burning (and possibly exploding) gas mixture, should it ignite? Experimental data on these systems, particularly for the newer coolant candidates, are limited. To assist in answering these questions, a mathematical model was developed to serve as a tool for predicting the potential detonation pressures and for estimating the composition limits of flammability for these systems based on empirical correlations between gas mixture thermodynamics and flammability for known systems. The present model uses the thermodynamic equilibrium to determine the reaction endpoint of a reactive gas mixture and uses detonation theory to estimate an upper bound to the pressure that could be generated upon ignition. The model described and documented in this report is an extended version of related models developed in 1992 and 1999.

  17. Cytochrome c biosensor--a model for gas sensing.

    Science.gov (United States)

    Hulko, Michael; Hospach, Ingeborg; Krasteva, Nadejda; Nelles, Gabriele

    2011-01-01

    This work is about gas biosensing with a cytochrome c biosensor. Emphasis is put on the analysis of the sensing process and a mathematical model to make predictions about the biosensor response. Reliable predictions about biosensor responses can provide valuable information and facilitate biosensor development, particularly at an early development stage. The sensing process comprises several individual steps, such as phase partition equilibrium, intermediate reactions, mass-transport, and reaction kinetics, which take place in and between the gas and liquid phases. A quantitative description of each step was worked out and finally combined into a mathematical model. The applicability of the model was demonstrated for a particular example of methanethiol gas detection by a cytochrome c biosensor. The model allowed us to predict the optical readout response of the biosensor from tabulated data and data obtained in simple liquid phase experiments. The prediction was experimentally verified with a planar three-electrode electro-optical cytochrome c biosensor in contact with methanethiol gas in a gas tight spectroelectrochemical measurement cell.

  18. Mathematical Modelling of Gas Fields Conversion into UGS Facilities

    Directory of Open Access Journals (Sweden)

    Štefanoviè Michal

    2004-09-01

    Full Text Available Nowadays the application of mathematical simulation at assessing the suitability of reservoirs for conversion into UGS facilities is a world-wide standard practice. The higher is the quality of input reservoir data (3-D seismic, well logging, core analyses, welltesting, regular pressure and volume parameters monitoring the better is the reliability of reservoir simulation results. This paper is focused at presenting the assessment results of two depleted gas fields conversions into UGS facilities by using mathematical modelling. The gas reservoirs are very similar with respect to their gas deposit depths, GIP values, lithological trap types and rock properties. Both these reservoirs structures represent lithological types of traps and are formed from complex sandstone layers interbedded with clay bands. Accordingly the reservoir simulation results, in the first case the further gas field conversion was not recommended, the conversion suitability of the second reservoir structure was acknowledged.

  19. Model documentation Natural Gas Transmission and Distribution Model of the National Energy Modeling System. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-26

    The Natural Gas Transmission and Distribution Model (NGTDM) of the National Energy Modeling System is developed and maintained by the Energy Information Administration (EIA), Office of Integrated Analysis and Forecasting. This report documents the archived version of the NGTDM that was used to produce the natural gas forecasts presented in the Annual Energy Outlook 1996, (DOE/EIA-0383(96)). The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic approach, and provides detail on the methodology employed. Previously this report represented Volume I of a two-volume set. Volume II reported on model performance, detailing convergence criteria and properties, results of sensitivity testing, comparison of model outputs with the literature and/or other model results, and major unresolved issues.

  20. ACTIVE MODEL ROCKET STABILIZATION VIA COLD GAS THRUSTERS

    OpenAIRE

    Malyuta, Danylo; Collaud, Xavier; Martins Gaspar, Mikael; Rouaze, Gautier Marie Pierre; Pictet, Raimondo; Ivanov, Anton; Mullin, Nickolay

    2015-01-01

    This paper describes the development and testing of a reaction control system (RCS) for a model rocket named FALCO-4. The rocket uses cold gas jets to keep itself perfectly vertical at low speeds. We first describe the mechanical layout of FALCO-4 and the characteristics of the cold gas propulsion system. We then propose a dynamical model of the rocket and a control scheme based on decoupled PID regulators for roll, pitch and yaw. The control scheme is then evaluated based on MATLAB simulatio...

  1. Intermediate-generalized Chaplygin gas inflationary universe model

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, Ramon; Olivares, Marco; Videla, Nelson [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Casilla, Valparaiso (Chile)

    2013-01-15

    An intermediate inflationary universe model in the context of a generalized Chaplygin gas is considered. For the matter we consider two different energy densities; a standard scalar field and a tachyon field, respectively. In general, we discuss the conditions of an inflationary epoch for these models. We also, use recent astronomical observations from Wilkinson Microwave Anisotropy Probe seven year data for constraining the parameters appearing in our models. (orig.)

  2. Computational technology of multiscale modeling the gas flows in microchannels

    Science.gov (United States)

    Podryga, V. O.

    2016-11-01

    The work is devoted to modeling the gas mixture flows in engineering microchannels under conditions of many scales of computational domain. The computational technology of using the multiscale approach combining macro - and microscopic models is presented. At macrolevel the nature of the flow and the external influence on it are considered. As a model the system of quasigasdynamic equations is selected. At microlevel the correction of gasdynamic parameters and the determination of boundary conditions are made. As a numerical model the Newton's equations and the molecular dynamics method are selected. Different algorithm types used for implementation of multiscale modeling are considered. The results of the model problems for separate stages are given.

  3. Hydrodynamical Models of Gas Cloud - Galaxy Collisions

    Science.gov (United States)

    Franklin, M.; Dinge, D.; Jones, T.; Benjamin, B.

    1999-05-01

    Clouds of neutral hydrogen falling toward the Galactic plane with a speed of about 100 km/s or more are among those considered to be "high velocity clouds" (HVCs). As HVCs are often observed approaching the midplane, the collision of such clouds with the gaseous disk of the Galaxy has been proposed as a precursor event to the phenomena known as "supershells" and as a catalyst to star formation. While many previous analytic calculations have assumed that ram pressure of the resisting medium was negligible, and a ballistic approximation was valid, observations showing a correlation between speed and increased height above the plane, the opposite of what is expected for free fall, suggest otherwise. Benjamin & Danly suggested in 1997 that clouds falling at terminal velocity provide a simple explanation for the observed velocity distribution. In this work, numerical models are used to test the above hypotheses with clouds falling through a more modern model of the interstellar medium than that used in the seminal work by Tenorio-Tagle et al. (TT) in 1987. With the addition of more dense material to the model background, clouds were still able to form supershell-like remnants, though star formation does not appear to be triggered. Further, though agreement was not perfect, the terminal velocity model was found to be a better approximation for these clouds' fall than the ballistic case. Cooling was a physical process included in TT's work which was not included here, but was found to be non-negligible. Simulations which include a cooling algorithm must be done to confirm these results. This work was supported in part by NSF grant AST96-19438.

  4. Off-gas Adsorption Model and Simulation - OSPREY

    Energy Technology Data Exchange (ETDEWEB)

    Veronica J Rutledge

    2013-10-01

    The absence of industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other countries. Thus, it is essential to model complex series of unit operations to simulate, understand, and predict inherent transient behavior. A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes is expected to provide substantial cost savings and many technical benefits. To support this capability, a modeling effort focused on the off-gas treatment system of a used nuclear fuel recycling facility is in progress. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed within Multi-physics Object Oriented Simulation Environment (MOOSE) developed at the Idaho National Laboratory (INL). Off-gas Separation and REcoverY (OSPREY) models the adsorption of offgas constituents for dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions. Inputs to the model include gas composition, sorbent and column properties, equilibrium and kinetic data, and inlet conditions. The simulation outputs component concentrations along the column length as a function of time from which breakthrough data can be obtained. The breakthrough data can be used to determine bed capacity, which in turn can be used to size columns. In addition to concentration data, the model predicts temperature along the column length as a function of time and pressure drop along the column length. A description of the OSPREY model, results from krypton adsorption modeling and plans for modeling the behavior of iodine, xenon, and tritium will be discussed.

  5. Gas phase metal cluster model systems for heterogeneous catalysis.

    Science.gov (United States)

    Lang, Sandra M; Bernhardt, Thorsten M

    2012-07-14

    Since the advent of intense cluster sources, physical and chemical properties of isolated metal clusters are an active field of research. In particular, gas phase metal clusters represent ideal model systems to gain molecular level insight into the energetics and kinetics of metal-mediated catalytic reactions. Here we summarize experimental reactivity studies as well as investigations of thermal catalytic reaction cycles on small gas phase metal clusters, mostly in relation to the surprising catalytic activity of nanoscale gold particles. A particular emphasis is put on the importance of conceptual insights gained through the study of gas phase model systems. Based on these concepts future perspectives are formulated in terms of variation and optimization of catalytic materials e.g. by utilization of bimetals and metal oxides. Furthermore, the future potential of bio-inspired catalytic material systems are highlighted and technical developments are discussed.

  6. Late time attractors of some varying Chaplygin gas cosmological models

    CERN Document Server

    Khurshudyan, M

    2015-01-01

    Varying Chaplygin gas is one of the dark fluids actively studied in modern cosmology. It does belong to the group of the fluids which has an explicitly given EoS. From the other hand phase space does contain all possible states of the system. Therefore, phase space analysis of the cosmological models does allow to understand qualitative behavior and estimate required characteristics of the models. Phase space analysis is a convenient approach to study a cosmological model, because we do not need to solve a system of differential equations for a given initial conditions, instead, we need to deal with appropriate algebraic equations. The goal of this paper is to find late time attractors for the cosmological models, where a varying Chaplygin gas is one of the components of the large sale universe. We will pay our attention to some non linear interacting models.

  7. Modeling CO2 air dispersion from gas driven lake eruptions

    Science.gov (United States)

    Chiodini, Giovanni; Costa, Antonio; Rouwet, Dmitri; Tassi, Franco

    2016-04-01

    The most tragic event of gas driven lake eruption occurred at Lake Nyos (Cameroon) on 21 August 1986, when a dense cloud of CO2 suffocated more than 1700 people and an uncounted number of animals in just one night. The event stimulated a series of researches aimed to understand gas origins, gas release mechanisms and strategies for gas hazard mitigation. Very few studies have been carried out for describing the transport of dense CO2 clouds in the atmosphere. Although from a theoretical point of view, gas dispersion can be fully studied by solving the complete equations system for mass, momentum and energy transport, in actual practice, different simplified models able to describe only specific phases or aspects have to be used. In order to simulate dispersion of a heavy gas and to assess the consequent hazard we used a model based on a shallow layer approach (TWODEE2). This technique which uses depth-averaged variables to describe the flow behavior of dense gas over complex topography represents a good compromise between the complexity of computational fluid dynamic models and the simpler integral models. Recently the model has been applied for simulating CO2 dispersion from natural gas emissions in Central Italy. The results have shown how the dispersion pattern is strongly affected by the intensity of gas release, the topography and the ambient wind speed. Here for the first time we applied TWODEE2 code to simulate the dispersion of the large CO2 clouds released by limnic eruptions. An application concerns the case of the 1986 event at lake Nyos. Some difficulties for the simulations were related to the lack of quantitative information: gas flux estimations are not well constrained, meteorological conditions are only qualitatively known, the digital model of the terrain is of poor quality. Different scenarios were taken into account in order to reproduce the qualitative observations available for such episode. The observations regard mainly the effects of gas on

  8. Modeling acid-gas generation from boiling chloride brines

    Directory of Open Access Journals (Sweden)

    Sonnenthal Eric

    2009-11-01

    Full Text Available Abstract Background This study investigates the generation of HCl and other acid gases from boiling calcium chloride dominated waters at atmospheric pressure, primarily using numerical modeling. The main focus of this investigation relates to the long-term geologic disposal of nuclear waste at Yucca Mountain, Nevada, where pore waters around waste-emplacement tunnels are expected to undergo boiling and evaporative concentration as a result of the heat released by spent nuclear fuel. Processes that are modeled include boiling of highly concentrated solutions, gas transport, and gas condensation accompanied by the dissociation of acid gases, causing low-pH condensate. Results Simple calculations are first carried out to evaluate condensate pH as a function of HCl gas fugacity and condensed water fraction for a vapor equilibrated with saturated calcium chloride brine at 50-150°C and 1 bar. The distillation of a calcium-chloride-dominated brine is then simulated with a reactive transport model using a brine composition representative of partially evaporated calcium-rich pore waters at Yucca Mountain. Results show a significant increase in boiling temperature from evaporative concentration, as well as low pH in condensates, particularly for dynamic systems where partial condensation takes place, which result in enrichment of HCl in condensates. These results are in qualitative agreement with experimental data from other studies. Conclusion The combination of reactive transport with multicomponent brine chemistry to study evaporation, boiling, and the potential for acid gas generation at the proposed Yucca Mountain repository is seen as an improvement relative to previously applied simpler batch evaporation models. This approach allows the evaluation of thermal, hydrological, and chemical (THC processes in a coupled manner, and modeling of settings much more relevant to actual field conditions than the distillation experiment considered. The actual

  9. Modeling acid-gas generation from boiling chloride brines

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guoxiang; Spycher, Nicolas; Sonnenthal, Eric; Steefel, Carl

    2009-11-16

    This study investigates the generation of HCl and other acid gases from boiling calcium chloride dominated waters at atmospheric pressure, primarily using numerical modeling. The main focus of this investigation relates to the long-term geologic disposal of nuclear waste at Yucca Mountain, Nevada, where pore waters around waste-emplacement tunnels are expected to undergo boiling and evaporative concentration as a result of the heat released by spent nuclear fuel. Processes that are modeled include boiling of highly concentrated solutions, gas transport, and gas condensation accompanied by the dissociation of acid gases, causing low-pH condensate. Simple calculations are first carried out to evaluate condensate pH as a function of HCl gas fugacity and condensed water fraction for a vapor equilibrated with saturated calcium chloride brine at 50-150 C and 1 bar. The distillation of a calcium-chloride-dominated brine is then simulated with a reactive transport model using a brine composition representative of partially evaporated calcium-rich pore waters at Yucca Mountain. Results show a significant increase in boiling temperature from evaporative concentration, as well as low pH in condensates, particularly for dynamic systems where partial condensation takes place, which result in enrichment of HCl in condensates. These results are in qualitative agreement with experimental data from other studies. The combination of reactive transport with multicomponent brine chemistry to study evaporation, boiling, and the potential for acid gas generation at the proposed Yucca Mountain repository is seen as an improvement relative to previously applied simpler batch evaporation models. This approach allows the evaluation of thermal, hydrological, and chemical (THC) processes in a coupled manner, and modeling of settings much more relevant to actual field conditions than the distillation experiment considered. The actual and modeled distillation experiments do not represent

  10. Gas entrainment in scaled model of pool type LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, I.; Chandra, L.; Laxman, D.; Kumar, A.; Gopal, C.A.; Shivakumar, N.S.; Padmakumar, G.; Anand Babu, C.; Vaidyanathan, G. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India)

    2007-07-01

    The reactor Thermal hydraulics plays an important role for successful operation of Prototype Fast Breeder Reactor (PFBR), which is under construction at Kalpakkam, India. One of the issues to be resolved in PFBR is argon cover gas entrainment problem from free liquid sodium surface. The entrained cover gas may hinder the normal reactor operation. High free surface velocity along with the presence of various immersed components in the hot pool is the cause of gas entrainment from free surface. To reduce the free surface velocity and hence gas entrainment, ring type baffle plates were considered. Initially the optimum geometry of the baffle plate was arrived through numerical analysis using PHOENICS, a commercial computational fluid dynamics tool. Finally the experiments were conducted in a 1/4 scale water model of PFBR primary circuit with selected baffle plate geometry. It was found that a baffle plate with radial width of 125 mm in the model and located above intermediate heat exchanger is very effective to reduce the gas entrainment problem in PFBR. (authors)

  11. An apparent permeability model of shale gas under formation conditions

    Science.gov (United States)

    Chen, Peng; Jiang, Shan; Chen, Yan; Wang, Shanshan

    2017-08-01

    There are various types of pores in shale, mainly consisting of nanopores and micropores, causing flow regime variations and apparent permeability changes during the development of the reservoir. In this paper, a Knudsen number calculation model is proposed with the actual conditions of gas in a shale reservoir. Then, based on the distribution of pores in shale, an apparent permeability model is established using hydrodynamics, and a calculation method is put forward for the actual permeability of a reservoir. Finally, the Knudsen number model and the permeability correction coefficient model are used to analyze the flow regime and permeability correction coefficients in pores during the development of the shale gas reservoir. Results show that with a decreasing of pressure, the Knudsen number increases, the flow regime changes from continuous flow and slip flow to transition flow or free molecular flow. When the Knudsen number is Kn > 0.1, and with a further increasing of Kn, gas molecule slippage greatly intensifies and the permeability correction coefficient K app/Kd significantly increases. While the Knudsen number increases, the permeability correction coefficient significantly increases in the micropores and the small pores, but this does not appear in the macropores and the mesopores. These results can be used to guide flow regime analysis and production forecasting in shale gas reservoirs.

  12. Design and development of a simple laboratory model to detect (15)N enrichment in cyanobacterial biomass and extra cellular ammonia using (15)N gas.

    Science.gov (United States)

    Selvakumar, G; Gopalaswamy, G; Arulmozhiselvan, K

    2007-03-01

    A laboratory scale working model that could detect the (15)N enrichment in cyanobacterial biomass and extracellular ammonia, using (15)N gas under in vitro conditions was designed and fabricated. Using the model, (15)N enrichment of 0.48% atom excess was detected in the cyanobacterial biomass on the 30 d after inoculation. The (15)N enrichment increased linearly in the extracellular ammoniacal fraction from the 20 d onward. The model would prove to be a useful tool to quantify the extent of (15)N enrichment under in vitro conditions using (15)N gas.

  13. A description of the Galactic Center excess in the Minimal Supersymmetric Standard Model and the Dark Matter signatures for the LHC and direct and indire ct detection experiments

    CERN Document Server

    Caron, Sascha; Hendriks, Luc; de Austri, Roberto Ruiz; Weniger, Christoph

    2015-01-01

    Observations with the Fermi Large Area Telescope (LAT) indicate an excess in gamma rays originating from the center of our Galaxy. A possible explanation for this excess is the annihilation of Dark Matter particles. We have investigated the annihilation of neutralinos as Dark Matter candidates within the phenomenological Minimal Supersymmetric Standard Model (pMSSM). An iterative particle filter approach was used to search for solutions within the pMSSM. We found solutions that are consistent with astroparticle physics and collider experiments, and provide a reasonable fit to the energy spectrum of the excess. The neutralino is a Bino/Higgsino mixture and a mass in the range $84-92$~GeV yielding a Dark Matter relic density $0.06 < \\Omega h^2 <0.13$. These pMSSM solutions make clear forecasts for LHC, direct and indirect DM detection experiments. If the pMSSM explanation of the excess seen by Fermi-LAT is correct, a DM signal might be discovered soon.

  14. A heterogeneous model for gas transport in carbon molecular sieves.

    Science.gov (United States)

    Ding, L P; Yuan, Y X; Farooq, S; Bhatia, S K

    2005-01-18

    A dual resistance model with distribution of either barrier or pore diffusional activation energy is proposed in this work for gas transport in carbon molecular sieve (CMS) micropores. This is a novel approach in which the equilibrium is homogeneous, but the kinetics is heterogeneous. The model seems to provide a possible explanation for the concentration dependence of the thermodynamically corrected barrier and pore diffusion coefficients observed in previous studies from this laboratory on gas diffusion in CMS. The energy distribution is assumed to follow the gamma distribution function. It is shown that the energy distribution model can fully capture the behavior described by the empirical model established in earlier studies to account for the concentration dependence of thermodynamically corrected barrier and pore diffusion coefficients. A methodology is proposed for extracting energy distribution parameters, and it is further shown that the extracted energy distribution parameters can effectively predict integral uptake and column breakthrough profiles over a wide range of operating pressures.

  15. Evaluation of the gas production economics of the gas hydrate cyclic thermal injection model. [Cyclic thermal injection

    Energy Technology Data Exchange (ETDEWEB)

    Kuuskraa, V.A.; Hammersheimb, E.; Sawyer, W.

    1985-05-01

    The objective of the work performed under this directive is to assess whether gas hydrates could potentially be technically and economically recoverable. The technical potential and economics of recovering gas from a representative hydrate reservoir will be established using the cyclic thermal injection model, HYDMOD, appropriately modified for this effort, integrated with economics model for gas production on the North Slope of Alaska, and in the deep offshore Atlantic. The results from this effort are presented in this document. In Section 1, the engineering cost and financial analysis model used in performing the economic analysis of gas production from hydrates -- the Hydrates Gas Economics Model (HGEM) -- is described. Section 2 contains a users guide for HGEM. In Section 3, a preliminary economic assessment of the gas production economics of the gas hydrate cyclic thermal injection model is presented. Section 4 contains a summary critique of existing hydrate gas recovery models. Finally, Section 5 summarizes the model modification made to HYDMOD, the cyclic thermal injection model for hydrate gas recovery, in order to perform this analysis.

  16. Model-based dynamic control and optimization of gas networks

    Energy Technology Data Exchange (ETDEWEB)

    Hofsten, Kai

    2001-07-01

    This work contributes to the research on control, optimization and simulation of gas transmission systems to support the dispatch personnel at gas control centres for the decision makings in the daily operation of the natural gas transportation systems. Different control and optimization strategies have been studied. The focus is on the operation of long distance natural gas transportation systems. Stationary optimization in conjunction with linear model predictive control using state space models is proposed for supply security, the control of quality parameters and minimization of transportation costs for networks offering transportation services. The result from the stationary optimization together with a reformulation of a simplified fluid flow model formulates a linear dynamic optimization model. This model is used in a finite time control and state constrained linear model predictive controller. The deviation from the control and the state reference determined from the stationary optimization is penalized quadratically. Because of the time varying status of infrastructure, the control space is also generally time varying. When the average load is expected to change considerably, a new stationary optimization is performed, giving a new state and control reference together with a new dynamic model that is used for both optimization and state estimation. Another proposed control strategy is a control and output constrained nonlinear model predictive controller for the operation of gas transmission systems. Here, the objective is also the security of the supply, quality control and minimization of transportation costs. An output vector is defined, which together with a control vector are both penalized quadratically from their respective references in the objective function. The nonlinear model predictive controller can be combined with a stationary optimization. At each sampling instant, a non convex nonlinear programming problem is solved giving a local minimum

  17. An integral representation of functions in gas-kinetic models

    Science.gov (United States)

    Perepelitsa, Misha

    2016-08-01

    Motivated by the theory of kinetic models in gas dynamics, we obtain an integral representation of lower semicontinuous functions on {{{R}}^d,} {d≥1}. We use the representation to study the problem of compactness of a family of the solutions of the discrete time BGK model for the compressible Euler equations. We determine sufficient conditions for strong compactness of moments of kinetic densities, in terms of the measures from their integral representations.

  18. An integration scheme for stiff solid-gas reactor models

    Directory of Open Access Journals (Sweden)

    Bjarne A. Foss

    2001-04-01

    Full Text Available Many dynamic models encounter numerical integration problems because of a large span in the dynamic modes. In this paper we develop a numerical integration scheme for systems that include a gas phase, and solid and liquid phases, such as a gas-solid reactor. The method is based on neglecting fast dynamic modes and exploiting the structure of the algebraic equations. The integration method is suitable for a large class of industrially relevant systems. The methodology has proven remarkably efficient. It has in practice performed excellent and been a key factor for the success of the industrial simulator for electrochemical furnaces for ferro-alloy production.

  19. Beyond pressureless gas dynamics : Quadrature-based velocity moment models

    CERN Document Server

    Chalons, Christophe; Massot, Marc

    2010-01-01

    Following the seminal work of F. Bouchut on zero pressure gas dynamics which has been extensively used for gas particle-flows, the present contribution investigates quadrature-based velocity moments models for kinetic equations in the framework of the infinite Knudsen number limit, that is, for dilute clouds of small particles where the collision or coalescence probability asymptotically approaches zero. Such models define a hierarchy based on the number of moments and associated quadrature nodes, the first level of which leads to pressureless gas dynamics. We focus in particular on the four moment model where the flux closure is provided by a two-node quadrature in the velocity phase space and provide the right framework for studying both smooth and singular solutions. The link with both the kinetic underlying equation as well as with zero pressure gas dynamics is provided and we define the notion of measure solutions as well as the mathematical structure of the resulting system of four PDEs. We exhibit a fa...

  20. A Discussion on Mean Excess Plots

    CERN Document Server

    Ghosh, Souvik

    2009-01-01

    A widely used tool in the study of risk, insurance and extreme values is the mean excess plot. One use is for validating a Generalized Pareto model for the excess distribution. This paper investigates some theoretical and practical aspects of the use of the mean excess plot.

  1. Modeling the Conductivity of a Subnanosecond Breakdown Gas Switch

    Science.gov (United States)

    Chen, Jinhui; Scott Tyo, J.; Jerald Buchenauer, C.

    We present two different modeling methods for understanding subnanosecond breakdown processes in gas plasma switches. The first method uses a finite element time domain method in order to understand experimental measurements of the remote electromagnetic (EM) fields. This method only models the EM fields and is good for analysis, but lacks a predictive capability for the full nonlinear plasma system. The second modeling method uses a PIC code, and is fully self consistent. We make comparisons with experimental measurements and conclude that the PIC model may provide a good understanding of the subnanosecond breakdown phenomena.

  2. Microeconomics of the ideal gas like market models

    Science.gov (United States)

    Chakrabarti, Anindya S.; Chakrabarti, Bikas K.

    2009-10-01

    We develop a framework based on microeconomic theory from which the ideal gas like market models can be addressed. A kinetic exchange model based on that framework is proposed and its distributional features have been studied by considering its moments. Next, we derive the moments of the CC model (Eur. Phys. J. B 17 (2000) 167) as well. Some precise solutions are obtained which conform with the solutions obtained earlier. Finally, an output market is introduced with global price determination in the model with some necessary modifications.

  3. Extending the generalized Chaplygin gas model by using geometrothermodynamics

    CERN Document Server

    Aviles, Alejandro; Campuzano, Lorena; Quevedo, Hernando

    2012-01-01

    We use the formalism of geometrothermodynamics (GTD) to derive fundamental thermodynamic equations that are used to construct general relativistic cosmological models. In particular, we show that the simplest possible fundamental equation, which corresponds in GTD to a system with no internal thermodynamic interaction, describes the different fluids of the standard model of cosmology. In addition, a particular fundamental equation with internal thermodynamic interaction is shown to generate a new cosmological model that correctly describes the dark sector of the Universe and contains as a special case the generalized Chaplygin gas model.

  4. Natural Gas Transmission and Distribution Model of the National Energy Modeling System. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. The NGTDM is the model within the NEMS that represents the transmission, distribution, and pricing of natural gas. The model also includes representations of the end-use demand for natural gas, the production of domestic natural gas, and the availability of natural gas traded on the international market based on information received from other NEMS models. The NGTDM determines the flow of natural gas in an aggregate, domestic pipeline network, connecting domestic and foreign supply regions with 12 demand regions. The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic design, provides detail on the methodology employed, and describes the model inputs, outputs, and key assumptions. Subsequent chapters of this report provide: an overview of NGTDM; a description of the interface between the NEMS and NGTDM; an overview of the solution methodology of the NGTDM; the solution methodology for the Annual Flow Module; the solution methodology for the Distributor Tariff Module; the solution methodology for the Capacity Expansion Module; the solution methodology for the Pipeline Tariff Module; and a description of model assumptions, inputs, and outputs.

  5. Applicability of linearized Dusty Gas Model for multicomponent diffusion of gas mixtures in porous solids

    Directory of Open Access Journals (Sweden)

    Marković Jelena

    2007-01-01

    Full Text Available The transport of gaseous components through porous media could be described according to the well-known Fick model and its modifications. It is also known that Fick’s law is not suitable for predicting the fluxes in multicomponent gas mixtures, excluding binary mixtures. This model is still frequently used in chemical engineering because of its simplicity. Unfortunately, besides the Fick’s model there is no generally accepted model for mass transport through porous media (membranes, catalysts etc.. Numerous studies on transport through porous media reveal that Dusty Gas Model (DGM is superior in its ability to predict fluxes in multicomponent mixtures. Its wider application is limited by more complicated calculation procedures comparing to Fick’s model. It should be noted that there were efforts to simplify DGM in order to obtain satisfactory accurate results. In this paper linearized DGM, as the simplest form of DGM, is tested under conditions of zero system pressure drop, small pressure drop, and different temperatures. Published experimental data are used in testing the accuracy of the linearized procedure. It is shown that this simplified procedure is accurate enough compared to the standard more complicated calculations.

  6. Surface temperature excess in heterogeneous catalysis

    NARCIS (Netherlands)

    Zhu, L.

    2005-01-01

    In this dissertation we study the surface temperature excess in heterogeneous catalysis. For heterogeneous reactions, such as gas-solid catalytic reactions, the reactions take place at the interfaces between the two phases: the gas and the solid catalyst. Large amount of reaction heats are released

  7. Surface temperature excess in heterogeneous catalysis

    NARCIS (Netherlands)

    Zhu, L.

    2005-01-01

    In this dissertation we study the surface temperature excess in heterogeneous catalysis. For heterogeneous reactions, such as gas-solid catalytic reactions, the reactions take place at the interfaces between the two phases: the gas and the solid catalyst. Large amount of reaction heats are released

  8. Excess water dynamics in hydrotalcite: QENS study

    Indian Academy of Sciences (India)

    S Mitra; A Pramanik; D Chakrabarty; R Mukhopadhyay

    2004-08-01

    Results of the quasi-elastic neutron scattering (QENS) measurements on the dynamics of excess water in hydrotalcite sample with varied content of excess water are reported. Translational motion of excess water can be best described by random translational jump diffusion model. The observed increase in translational diffusivity with increase in the amount of excess water is attributed to the change in binding of the water molecules to the host layer.

  9. Model documentation: Natural Gas Transmission and Distribution Model of the National Energy Modeling System; Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-02-24

    The Natural Gas Transmission and Distribution Model (NGTDM) is a component of the National Energy Modeling System (NEMS) used to represent the domestic natural gas transmission and distribution system. NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the Energy Information Administration (EIA) and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. This report documents the archived version of NGTDM that was used to produce the natural gas forecasts used in support of the Annual Energy Outlook 1994, DOE/EIA-0383(94). The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic design, provides detail on the methodology employed, and describes the model inputs, outputs, and key assumptions. It is intended to fulfill the legal obligation of the EIA to provide adequate documentation in support of its models (Public Law 94-385, Section 57.b.2). This report represents Volume 1 of a two-volume set. (Volume 2 will report on model performance, detailing convergence criteria and properties, results of sensitivity testing, comparison of model outputs with the literature and/or other model results, and major unresolved issues.) Subsequent chapters of this report provide: (1) an overview of the NGTDM (Chapter 2); (2) a description of the interface between the National Energy Modeling System (NEMS) and the NGTDM (Chapter 3); (3) an overview of the solution methodology of the NGTDM (Chapter 4); (4) the solution methodology for the Annual Flow Module (Chapter 5); (5) the solution methodology for the Distributor Tariff Module (Chapter 6); (6) the solution methodology for the Capacity Expansion Module (Chapter 7); (7) the solution methodology for the Pipeline Tariff Module (Chapter 8); and (8) a description of model assumptions, inputs, and outputs (Chapter 9).

  10. A Paradigm for Modeling and Computation of Gas Dynamics

    CERN Document Server

    Xu, Kun

    2016-01-01

    In the continuum flow regime, the Navier-Stokes equations are usually used for the description of gas dynamics. On the other hand, the Boltzmann equation is applied for the rarefied gas dynamics. Both equations are constructed from modeling flow physics in different scales. Fortunately, due to the distinct separation of scales, i.e., the hydrodynamic and kinetic ones, both Navier-Stokes equations and the Boltzmann equation are valid in their respectable domains. However, in real physical application, there may not have such a distinctive scale separation. For example, around a hypersonic flying vehicle, the flow physics at different regions may correspond to different regimes, where the local Knudsen number can be changed in several order of magnitudes. With a variation of modeling scale, theoretically a continuous governing equation from kinetic Boltzmann equation to the hydrodynamic Navier-Stokes equations should exist. However, due to the difficulties of a direct modeling of flow physics in the scale betwe...

  11. MODELING AND AVAILABILITY ANALYZES OF A COMPLEX GAS PIPELINE NETWORK

    Energy Technology Data Exchange (ETDEWEB)

    Ainouche, A.; Ainouche, H.

    2007-07-01

    The network reliability, in the way of security of supply of international markets, is proved to be an essential criterion for the conservation of the market shares and the conquest of new customers. In relation with the importance and the existing configurations diversity of gas pipelines networks, the obtaining of a global availability model of a network is difficult to implement by the use of a classic approach based on the analysis of the whole of failure risks, the definition of their probability and the estimation of their impact in term of productivity. This because mainly of the huge dimensions of the phase space that would result from such a conception. To get round this problem we implemented a systemic type approach for the modeling of the availability of a complex gas pipelines network. The approach of modeling is of 'bottom-up' type. The model of coordination is a model of flow maximization whose formalization requires the representation of the gas pipeline network by the graphs theory. The developed tool can also be used as a stand of experimentation and to define by simulation the impact of every decision having the tendency to improve the availability of the network. (auth)

  12. Validation of DWPF Melter Off-Gas Combustion Model

    Energy Technology Data Exchange (ETDEWEB)

    Choi, A.S.

    2000-08-23

    The empirical melter off-gas combustion model currently used in the DWPF safety basis calculations is valid at melter vapor space temperatures above 570 degrees C, as measured in the thermowell. This lower temperature bound coincides with that of the off-gas data used as the basis of the model. In this study, the applicability of the empirical model in a wider temperature range was assessed using the off-gas data collected during two small-scale research melter runs. The first data set came from the Small Cylindrical Melter-2 run in 1985 with the sludge feed coupled with the precipitate hydrolysis product. The second data set came from the 774-A melter run in 1996 with the sludge-only feed prepared with the modified acid addition strategy during the feed pretreatment step. The results of the assessment showed that the data from these two melter runs agreed well with the existing model, and further provided the basis for extending the lower temperature bound of the model to the measured melter vapor space temperature of 445 degrees C.

  13. A multilevel excess hazard model to estimate net survival on hierarchical data allowing for non-linear and non-proportional effects of covariates.

    Science.gov (United States)

    Charvat, Hadrien; Remontet, Laurent; Bossard, Nadine; Roche, Laurent; Dejardin, Olivier; Rachet, Bernard; Launoy, Guy; Belot, Aurélien

    2016-08-15

    The excess hazard regression model is an approach developed for the analysis of cancer registry data to estimate net survival, that is, the survival of cancer patients that would be observed if cancer was the only cause of death. Cancer registry data typically possess a hierarchical structure: individuals from the same geographical unit share common characteristics such as proximity to a large hospital that may influence access to and quality of health care, so that their survival times might be correlated. As a consequence, correct statistical inference regarding the estimation of net survival and the effect of covariates should take this hierarchical structure into account. It becomes particularly important as many studies in cancer epidemiology aim at studying the effect on the excess mortality hazard of variables, such as deprivation indexes, often available only at the ecological level rather than at the individual level. We developed here an approach to fit a flexible excess hazard model including a random effect to describe the unobserved heterogeneity existing between different clusters of individuals, and with the possibility to estimate non-linear and time-dependent effects of covariates. We demonstrated the overall good performance of the proposed approach in a simulation study that assessed the impact on parameter estimates of the number of clusters, their size and their level of unbalance. We then used this multilevel model to describe the effect of a deprivation index defined at the geographical level on the excess mortality hazard of patients diagnosed with cancer of the oral cavity. Copyright © 2016 John Wiley & Sons, Ltd.

  14. Estimating methane gas generation from Devil's swamp landfill using greenhouse gas emission models

    Science.gov (United States)

    Adeyemi, Ayodeji Thompson

    Greenhouse gas (GHG) has been a key issue in the study, design, and management of landfills. Landfill gas (LFG) is considered either as a significant source of renewable energy (if extracted and processed accordingly) or significant source of pollution and risk (if not mitigated or processed). A municipal solid waste (MSW) landfill emits a significant amount of methane, a potent GHG. Thus, quantification and mitigation of GHG emissions is an important area of study in engineering and other sciences related to landfill technology and management. The present study will focus on estimating methane generation from Devils swamp landfill (DSLF), a closed landfill in Baton Rouge, LA. The landfill operated for 53 years (1940-1993) and contains both industrial and municipal waste products. Since the Clean Air Act of 1963, landfills are now classified as New Source Performance Standard (NSPS) waste (i.e., waste that will decompose to generate LFG). Currently, the DSLF is being used as source of renewable energy through the "Waste to Energy" program. For this study, to estimate the methane potential in the DSLF, it is important to determine the characteristics and classification of the landfill's wastes. The study uses and compares different GHG modeling tools---LandGEM, a multiphase model, and a simple first-order model---to estimate methane gas emission and compare results with the actual emissions from the DSLF. The sensitivity of the methane generation rate was analyzed by the methane generation models to assess the effects of variables such as initial conditions, specific growth rate, and reaction rate constants. The study concludes that methane (L0) and initial organic concentration in waste (k) are the most important parameters when estimating methane generation using the models.

  15. Mathematical Model of Natural Gas Desulfurization Based on Membrane Absorption

    Institute of Scientific and Technical Information of China (English)

    Wang Shuli; Ma Jun; Wang Ganyu; Zhou Heng

    2014-01-01

    Models of mass transfer kinetics combined with mass transfer differential equation and mass transfer resistance equation were established on the basis of double-iflm theory. Mass transfer process of H2S absorption by means of polypro-pylene hydrophobic microporous hollow ifber membrane contactor was simulated using MDEA (N-methyldiethanolamine) as the absorption liquid and corresponding experiments of natural gas desulfurization were performed. The simulation re-sults indicated that the removal rate of hydrogen sulifde showed positive dependence on the absorption liquid concentration and gas pressure. However, the desulfurization rate showed negative dependence on gas lfow. The simulated values were in good agreement with the experimental results. The in-tube concentration of hydrogen sulifde at the same point increased with increase in the gas velocity. Axial concentration of hydrogen sulifde decreased rapidly at the beginning, and the de-crease saw a slowdown during the latter half period. Hydrogen sulifde concentration dropped quickly in the radial direction, and the reduction in the radial direction was weakened with the increase of axial length due to the gradual reduction of hy-drogen sulifde concentration along the tube. The desulfurization rate under given operating conditions can be predicted by this model, and the theoretical basis for membrane module design can also be provided.

  16. Modeling the Pollution of Pristine Gas in the Early Universe

    CERN Document Server

    Pan, Liubin; Scalo, John

    2013-01-01

    We conduct a comprehensive theoretical and numerical investigation of the pollution of pristine gas in turbulent flows, designed to provide new tools for modeling the evolution of the first generation of stars. The properties of such Population III (Pop III) stars are thought to be very different than later generations, because cooling is dramatically different in gas with a metallicity below a critical value Z_c, which lies between ~10^-6 and 10^-3 solar value. Z_c is much smaller than the typical average metallicity, , and thus the mixing efficiency of the pristine gas in the interstellar medium plays a crucial role in the transition from Pop III to normal star formation. The small critical value, Z_c, corresponds to the far left tail of the probability distribution function (PDF) of the metallicity. Based on closure models for the PDF formulation of turbulent mixing, we derive equations for the fraction of gas, P, lying below Z_c, in compressible turbulence. Our simulation data shows that the evolution of ...

  17. Off-Gas Adsorption Model Capabilities and Recommendations

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, Kevin L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Welty, Amy K. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Law, Jack [Idaho National Lab. (INL), Idaho Falls, ID (United States); Ladshaw, Austin [Georgia Inst. of Technology, Atlanta, GA (United States); Yiacoumi, Sotira [Georgia Inst. of Technology, Atlanta, GA (United States); Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-03-01

    Off-gas treatment is required to reduce emissions from aqueous fuel reprocessing. Evaluating the products of innovative gas adsorption research requires increased computational simulation capability to more effectively transition from fundamental research to operational design. Early modeling efforts produced the Off-Gas SeParation and REcoverY (OSPREY) model that, while efficient in terms of computation time, was of limited value for complex systems. However, the computational and programming lessons learned in development of the initial model were used to develop Discontinuous Galerkin OSPREY (DGOSPREY), a more effective model. Initial comparisons between OSPREY and DGOSPREY show that, while OSPREY does reasonably well to capture the initial breakthrough time, it displays far too much numerical dispersion to accurately capture the real shape of the breakthrough curves. DGOSPREY is a much better tool as it utilizes a more stable set of numerical methods. In addition, DGOSPREY has shown the capability to capture complex, multispecies adsorption behavior, while OSPREY currently only works for a single adsorbing species. This capability makes DGOSPREY ultimately a more practical tool for real world simulations involving many different gas species. While DGOSPREY has initially performed very well, there is still need for improvement. The current state of DGOSPREY does not include any micro-scale adsorption kinetics and therefore assumes instantaneous adsorption. This is a major source of error in predicting water vapor breakthrough because the kinetics of that adsorption mechanism is particularly slow. However, this deficiency can be remedied by building kinetic kernels into DGOSPREY. Another source of error in DGOSPREY stems from data gaps in single species, such as Kr and Xe, isotherms. Since isotherm data for each gas is currently available at a single temperature, the model is unable to predict adsorption at temperatures outside of the set of data currently

  18. Modified lattice-gas model for the gas-liquid-solid phase diagram

    Science.gov (United States)

    Imry, Yoseph; Schwartz, Moshe

    1980-04-01

    Crystalline order parameters related to the localization of the particles within the cells are introduced into the usual lattice-gas model. The coupling of these order parameters to the usual liquid-gas transition is shown to produce, in the simplest approximation, phase diagrams of qualitatively correct shapes. The Goldstone modes of the solid are retained in this picture. The Landau theory of melting is reviewed and shown to always lead to a first-order solid-fluid transition. The question of the possibility of the transition becoming second order due to fluctuations is discussed qualitatively. This possibility is shown to depend on the relative sizes of the first-order transition and the critical region of the fluctuations.

  19. Explaining 750 GeV diphoton excess from top/bottom partner cascade decay in two-Higgs-doublet model extension

    CERN Document Server

    Han, Xiao-Fang; Wu, Lei; Yang, Jin Min; Zhang, Mengchao

    2016-01-01

    In this paper, we interpret the 750 GeV diphoton excess in the Zee-Babu extension of the two-Higgs-doublet model by introducing a top partner ($T$)/bottom partner ($B$). In the alignment limit, the 750 GeV resonance is identified as the heavy CP-even Higgs boson ($H$), which can be sizably produced via the QCD process $pp \\to T\\bar{T}$ or $pp \\to B\\bar{B}$ followed by the decay $T\\to Ht$ or $B \\to Hb$. The diphoton decay rate of $H$ is greatly enhanced by the charged singlet scalars predicted in the Zee-Babu extension and the total width of $H$ can be as large as 7 GeV. Under the current LHC constraints, we scan the parameter space and find that such an extension can account for the observed diphoton excess.

  20. Stochastic Lattice Gas Model for a Predator-Prey System

    CERN Document Server

    Satulovsky, J E; Satulovsky, Javier; Tome, Tania

    1994-01-01

    We propose a stochastic lattice gas model to describe the dynamics of two animal species population, one being a predator and the other a prey. This model comprehends the mechanisms of the Lotka-Volterra model. Our analysis was performed by using a dynamical mean-field approximation and computer simulations. Our results show that the system exhibits an oscillatory behavior of the population densities of prey and predators. For the sets of parameters used in our computer simulations, these oscillations occur at a local level. Mean-field results predict synchronized collective oscillations.

  1. Sorption Modeling and Verification for Off-Gas Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tavlarides, Lawrence [Syracuse Univ., NY (United States); Yiacoumi, Sotira [Georgia Inst. of Technology, Atlanta, GA (United States); Tsouris, Costas [Georgia Inst. of Technology, Atlanta, GA (United States); Gabitto, Jorge [Prairie View Texas A& M; DePaoli, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-12-20

    This project was successfully executed to provide valuable adsorption data and improve a comprehensive model developed in previous work by the authors. Data obtained were used in an integrated computer program to predict the behavior of adsorption columns. The model is supported by experimental data and has been shown to predict capture of off gas similar to that evolving during the reprocessing of nuclear waste. The computer program structure contains (a) equilibrium models of off-gases with the adsorbate; (b) mass-transfer models to describe off-gas mass transfer to a particle, diffusion through the pores of the particle, and adsorption on the active sites of the particle; and (c) incorporation of these models into fixed bed adsorption modeling, which includes advection through the bed. These models are being connected with the MOOSE (Multiphysics Object-Oriented Simulation Environment) software developed at the Idaho National Laboratory through DGOSPREY (Discontinuous Galerkin Off-gas SeParation and REcoverY) computer codes developed in this project. Experiments for iodine and water adsorption have been conducted on reduced silver mordenite (Ag0Z) for single layered particles. Adsorption apparatuses have been constructed to execute these experiments over a useful range of conditions for temperatures ranging from ambient to 250°C and water dew points ranging from -69 to 19°C. Experimental results were analyzed to determine mass transfer and diffusion of these gases into the particles and to determine which models best describe the single and binary component mass transfer and diffusion processes. The experimental results were also used to demonstrate the capabilities of the comprehensive models developed to predict single-particle adsorption and transients of the adsorption-desorption processes in fixed beds. Models for adsorption and mass transfer have been developed to mathematically describe adsorption kinetics and transport via diffusion and advection

  2. The Herschel view of Gas in Protoplanetary Systems (GASPS). First comparisons with a large grid of models

    CERN Document Server

    Pinte, C; Menard, F; Duchene, G; Kamp, I; Meeus, G; Mathews, G S; Howard, C D; Grady, C A; Thi, W -F; Tilling, I; Augereau, J -C; Dent, W R F; Alacid, J M; Andrews, S; Ardila, D R; Aresu, G; Barrado, D; Brittain, S; Ciardi, D R; Danchi, W; Eiroa, C; Fedele, D; de Gregorio-Monsalvo, I; Heras, A; Huelamo, N; Krivov, A; Lebreton, J; Liseau, R; Martin-Zaidi, C; Mendigutia, I; Montesinos, B; Mora, A; Morales-Calderon, M; Nomura, H; Pantin, E; Pascucci, I; Phillips, N; Podio, L; Poelman, D R; Ramsay, S; Riaz, B; Rice, K; Riviere-Marichalar, P; Roberge, A; Sandell, G; Solano, E; Vandenbussche, B; Walker, H; Williams, J P; White, G J; Wright, G

    2010-01-01

    The Herschel GASPS Key Program is a survey of the gas phase of protoplanetary discs, targeting 240 objects which cover a large range of ages, spectral types, and disc properties. To interpret this large quantity of data and initiate self-consistent analyses of the gas and dust properties of protoplanetary discs, we have combined the capabilities of the radiative transfer code MCFOST with the gas thermal balance and chemistry code ProDiMo to compute a grid of 300 000 disc models (DENT). We present a comparison of the first Herschel/GASPS line and continuum data with the predictions from the DENT grid of models. Our objective is to test some of the main trends already identified in the DENT grid, as well as to define better empirical diagnostics to estimate the total gas mass of protoplanetary discs. Photospheric UV radiation appears to be the dominant gas-heating mechanism for Herbig stars, whereas UV excess and/or X-rays emission dominates for T Tauri stars. The DENT grid reveals the complexity in the analysi...

  3. An Updated Gas/grain Sulfur Network for Astrochemical Models

    Science.gov (United States)

    Laas, Jacob; Caselli, Paola

    2017-06-01

    Sulfur is a chemical element that enjoys one of the highest cosmic abundances. However, it has traditionally played a relatively minor role in the field of astrochemistry, being drowned out by other chemistries after it depletes from the gas phase during the transition from a diffuse cloud to a dense one. A wealth of laboratory studies have provided clues to its rich chemistry in the condensed phase, and most recently, a report by a team behind the Rosetta spacecraft has significantly helped to unveil its rich cometary chemistry. We have set forth to use this information to greatly update/extend the sulfur reactions within the OSU gas/grain astrochemical network in a systematic way, to provide more realistic chemical models of sulfur for a variety of interstellar environments. We present here some results and implications of these models.

  4. Streptococcus mutans forms xylitol-resistant biofilm on excess adhesive flash in novel ex-vivo orthodontic bracket model.

    Science.gov (United States)

    Ho, Cindy S F; Ming, Yue; Foong, Kelvin W C; Rosa, Vinicius; Thuyen, Truong; Seneviratne, Chaminda J

    2017-04-01

    During orthodontic bonding procedures, excess adhesive is invariably left on the tooth surface at the interface between the bracket and the enamel junction; it is called excess adhesive flash (EAF). We comparatively evaluated the biofilm formation of Streptococcus mutans on EAF produced by 2 adhesives and examined the therapeutic efficacy of xylitol on S mutans formed on EAF. First, we investigated the biofilm formation of S mutans on 3 orthodontic bracket types: stainless steel preadjusted edgewise, ceramic preadjusted edgewise, and stainless steel self-ligating. Subsequently, tooth-colored Transbond XT (3M Unitek, Monrovia, Calif) and green Grengloo (Ormco, Glendora, Calif) adhesives were used for bonding ceramic brackets to extracted teeth. S mutans biofilms on EAF produced by the adhesives were studied using the crystal violet assay and scanning electron microscopy. Surface roughness and surface energy of the EAF were examined. The therapeutic efficacies of different concentrations of xylitol were tested on S mutans biofilms. Significantly higher biofilms were formed on the ceramic preadjusted edgewise brackets (P = 0.003). Transbond XT had significantly higher S mutans biofilms compared with Grengloo surfaces (P = 0.007). There was no significant difference in surface roughness between Transbond XT and Grengloo surfaces (P >0.05). Surface energy of Transbond XT had a considerably smaller contact angle than did Grengloo, suggesting that Transbond XT is a more hydrophilic material. Xylitol at low concentrations had no significant effect on the reduction of S mutans biofilms on orthodontic adhesives (P = 0.016). Transbond XT orthodontic adhesive resulted in more S mutans biofilm compared with Grengloo adhesive on ceramic brackets. Surface energy seemed to play a more important role than surface roughness for the formation of S mutans biofilm on EAF. Xylitol does not appear to have a therapeutic effect on mature S mutans biofilm. Copyright © 2017 American

  5. Multiscale model reduction for shale gas transport in fractured media

    CERN Document Server

    Akkutlu, I Y; Vasilyeva, Maria

    2015-01-01

    In this paper, we develop a multiscale model reduction technique that describes shale gas transport in fractured media. Due to the pore-scale heterogeneities and processes, we use upscaled models to describe the matrix. We follow our previous work \\cite{aes14}, where we derived an upscaled model in the form of generalized nonlinear diffusion model to describe the effects of kerogen. To model the interaction between the matrix and the fractures, we use Generalized Multiscale Finite Element Method. In this approach, the matrix and the fracture interaction is modeled via local multiscale basis functions. We developed the GMsFEM and applied for linear flows with horizontal or vertical fracture orientations on a Cartesian fine grid. In this paper, we consider arbitrary fracture orientations and use triangular fine grid and developed GMsFEM for nonlinear flows. Moreover, we develop online basis function strategies to adaptively improve the convergence. The number of multiscale basis functions in each coarse region ...

  6. Dense Molecular Gas: A Sensitive Probe of Stellar Feedback Models

    CERN Document Server

    Hopkins, Philip F; Murray, Norman; Quataert, Eliot

    2012-01-01

    We show that the mass fraction of GMC gas (n>100 cm^-3) in dense (n>>10^4 cm^-3) star-forming clumps, observable in dense molecular tracers (L_HCN/L_CO(1-0)), is a sensitive probe of the strength and mechanism(s) of stellar feedback. Using high-resolution galaxy-scale simulations with pc-scale resolution and explicit models for feedback from radiation pressure, photoionization heating, stellar winds, and supernovae (SNe), we make predictions for the dense molecular gas tracers as a function of GMC and galaxy properties and the efficiency of stellar feedback. In models with weak/no feedback, much of the mass in GMCs collapses into dense sub-units, predicting L_HCN/L_CO(1-0) ratios order-of-magnitude larger than observed. By contrast, models with feedback properties taken directly from stellar evolution calculations predict dense gas tracers in good agreement with observations. Changing the strength or timing of SNe tends to move systems along, rather than off, the L_HCN-L_CO relation (because SNe heat lower-de...

  7. Planning the network of gas pipelines through modeling tools

    Energy Technology Data Exchange (ETDEWEB)

    Sucupira, Marcos L.L.; Lutif Filho, Raimundo B. [Companhia de Gas do Ceara (CEGAS), Fortaleza, CE (Brazil)

    2009-07-01

    Natural gas is a source of non-renewable energy used by different sectors of the economy of Ceara. Its use may be industrial, residential, commercial, as a source of automotive fuel, as a co-generation of energy and as a source for generating electricity from heat. For its practicality this energy has a strong market acceptance and provides a broad list of clients to fit their use, which makes it possible to reach diverse parts of the city. Its distribution requires a complex network of pipelines that branches throughout the city to meet all potential clients interested in this source of energy. To facilitate the design, analysis, expansion and location of bottlenecks and breaks in the distribution network, a modeling software is used that allows the network manager of the net to manage the various information about the network. This paper presents the advantages of modeling the gas distribution network of natural gas companies in Ceara, showing the tool used, the steps necessary for the implementation of the models, the advantages of using the software and the findings obtained with its use. (author)

  8. Homogeneous gas phase models of relaxation kinetics in neon afterglow

    Directory of Open Access Journals (Sweden)

    Marković Vidosav Lj.

    2007-01-01

    Full Text Available The homogeneous gas phase models of relaxation kinetics (application of the gas phase effective coefficients to represent surface losses are applied for the study of charged and neutral active particles decay in neon afterglow. The experimental data obtained by the breakdown time delay measurements as a function of the relaxation time td (τ (memory curve is modeled in early, as well as in late afterglow. The number density decay of metastable states can explain neither the early, nor the late afterglow kinetics (memory effect, because their effective lifetimes are of the order of milliseconds and are determined by numerous collision quenching processes. The afterglow kinetics up to hundreds of milliseconds is dominated by the decay of molecular neon Ne2 + and nitrogen ions N2 + (present as impurities and the approximate value of N2 + ambipolar diffusion coefficient is determined. After the charged particle decay, the secondary emitted electrons from the surface catalyzed excitation of nitrogen atoms on the cathode determine the breakdown time delay down to the cosmic rays and natural radioactivity level. Due to the neglecting of number density spatial profiles, the homogeneous gas phase models give only the approximate values of the corresponding coefficients, but reproduce correctly other characteristics of afterglow kinetics from simple fits to the experimental data.

  9. Excessive Daytime Sleepiness

    Directory of Open Access Journals (Sweden)

    Yavuz Selvi

    2016-06-01

    Full Text Available Excessive daytime sleepiness is one of the most common sleep-related patient symptoms, with preva-lence in the community estimated to be as high as 18%. Patients with excessive daytime sleepiness may exhibit life threatening road and work accidents, social maladjustment, decreased academic and occupational performance and have poorer health than comparable adults. Thus, excessive daytime sleepiness is a serious condition that requires investigation, diagnosis and treatment primarily. As with most medical condition, evaluation of excessive daytime sleepiness begins a precise history and various objective and subjective tools have been also developed to assess excessive daytime sleepiness. The most common causes of excessive daytime sleepiness are insufficient sleep hygiene, chronic sleep deprivation, medical and psychiatric conditions and sleep disorders, such as obstructive sleep apnea, medications, and narcolepsy. Treatment option should address underlying contributors and promote sleep quantity by ensuring good sleep hygiene. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2016; 8(2: 114-132

  10. Semiphenomenological model for gas-liquid phase transitions.

    Science.gov (United States)

    Benilov, E S; Benilov, M S

    2016-03-01

    We examine a rarefied gas with inter-molecular attraction. It is argued that the attraction force amplifies random density fluctuations by pulling molecules from lower-density regions into high-density regions and thus may give rise to an instability. To describe this effect, we use a kinetic equation where the attraction force is taken into account in a way similar to how electromagnetic forces in plasma are treated in the Vlasov model. It is demonstrated that the instability occurs when the temperature T is lower than a certain threshold value T(s) depending on the gas density. It is further shown that, even if T is only marginally lower than T(s), the instability generates clusters with density much higher than that of the gas. These results suggest that the instability should be interpreted as a gas-liquid phase transition, with T(s) being the temperature of saturated vapor and the high-density clusters representing liquid droplets.

  11. Excessive Daytime Sleepiness

    OpenAIRE

    Yavuz Selvi; Ali Kandeger; Ayca Asena Sayin

    2016-01-01

    Excessive daytime sleepiness is one of the most common sleep-related patient symptoms, with preva-lence in the community estimated to be as high as 18%. Patients with excessive daytime sleepiness may exhibit life threatening road and work accidents, social maladjustment, decreased academic and occupational performance and have poorer health than comparable adults. Thus, excessive daytime sleepiness is a serious condition that requires investigation, diagnosis and treatment primarily. As with ...

  12. Estimation of excess mortality due to long-term exposure to PM2.5 in Japan using a high-resolution model for present and future scenarios

    Science.gov (United States)

    Goto, Daisuke; Ueda, Kayo; Ng, Chris Fook Sheng; Takami, Akinori; Ariga, Toshinori; Matsuhashi, Keisuke; Nakajima, Teruyuki

    2016-09-01

    Particulate matter with a diameter of less than 2.5 μm, known as PM2.5, can affect human health, especially in elderly people. Because of the imminent aging of society in the near future in most developed countries, the human health impacts of PM2.5 must be evaluated. In this study, we used a global-to-regional atmospheric transport model to simulate PM2.5 in Japan with a high-resolution stretched grid system (∼10 km for the high-resolution model, HRM) for the present (the 2000) and the future (the 2030, as proposed by the Representative Concentrations Pathway 4.5, RCP4.5). We also used the same model with a low-resolution uniform grid system (∼100 km for the low-resolution model, LRM). These calculations were conducted by nudging meteorological fields obtained from an atmosphere-ocean coupled model and providing emission inventories used in the coupled model. After correcting for bias, we calculated the excess mortality due to long-term exposure to PM2.5 among the elderly (over 65 years old) based on different minimum PM2.5 concentration (MINPM) levels to account for uncertainty using the simulated PM2.5 distributions to express the health effect as a concentration-response function. As a result, we estimated the excess mortality for all of Japan to be 31,300 (95% confidence intervals: 20,700 to 42,600) people in 2000 and 28,600 (95% confidence intervals: 19,000 to 38,700) people in 2030 using the HRM with a MINPM of 5.8 μg/m3. In contrast, the LRM resulted in underestimates of approximately 30% (for PM2.5 concentrations in the 2000 and 2030), approximately 60% (excess mortality in the 2000) and approximately 90% (excess mortality in 2030) compared to the HRM results. We also found that the uncertainty in the MINPM value, especially for low PM2.5 concentrations in the future (2030) can cause large variability in the estimates, ranging from 0 (MINPM of 15 μg/m3 in both HRM and LRM) to 95,000 (MINPM of 0 μg/m3 in HRM) people.

  13. Filter-matrix lattice Boltzmann model for microchannel gas flows.

    Science.gov (United States)

    Zhuo, Congshan; Zhong, Chengwen

    2013-11-01

    The lattice Boltzmann method has been shown to be successful for microscale gas flows, and it has attracted significant research interest. In this paper, the recently proposed filter-matrix lattice Boltzmann (FMLB) model is first applied to study the microchannel gas flows, in which a Bosanquet-type effective viscosity is used to capture the flow behaviors in the transition regime. A kinetic boundary condition, the combined bounce-back and specular-reflection scheme with the second-order slip scheme, is also designed for the FMLB model. By analyzing a unidirectional flow, the slip velocity and the discrete effects related to the boundary condition are derived within the FMLB model, and a revised scheme is presented to overcome such effects, which have also been validated through numerical simulations. To gain an accurate simulation in a wide range of Knudsen numbers, covering the slip and the entire transition flow regimes, a set of slip coefficients with an introduced fitting function is adopted in the revised second-order slip boundary condition. The periodic and pressure-driven microchannel flows have been investigated by the present model in this study. The numerical results, including the velocity profile and the mass flow rate, as well as the nonlinear pressure distribution along the channel, agree fairly well with the solutions of the linearized Boltzmann equation, the direct simulation Monte Carlo results, the experimental data, and the previous results of the multiple effective relaxation lattice Boltzmann model. Also, the present results of the velocity profile and the mass flow rate show that the present model with the fitting function can yield improved predictions for the microchannel gas flow with higher Knudsen numbers in the transition flow regime.

  14. A lattice-gas model for amyloid fibril aggregation

    Science.gov (United States)

    Hong, Liu; Qi, Xianghong; Zhang, Yang

    2012-01-01

    A simple lattice-gas model, with two fundamental energy terms —elongation and nucleation effects, is proposed for understanding the mechanisms of amyloid fibril formation. Based on the analytical solution and Monte Carlo simulation of 1D system, we have thoroughly explored the dependence of mass concentration, number concentration of amyloid filaments and the lag-time on the initial protein concentration, the critical nucleus size, the strengths of nucleation and elongation effects, respectively. We also found that thickening process (self-association of filaments into multi-strand fibrils) is not essential for the modeling of amyloid filaments through simulations on 2D lattice. Compared with the kinetic model recently proposed by Knowles et al., highly quantitative consistency of two models in the calculation of mass fraction of filaments is found. Moreover our model can generate a better prediction on the number fraction, which is closer to experimental values when the elongation strength gets stronger. PMID:23275684

  15. Steady state cooling flow models with gas loss for normal elliptical galaxies

    Science.gov (United States)

    Sarazin, Craig L.; Ashe, Gregory A.

    1989-01-01

    A grid of cooling flow models for the hot gas in normal elliptical galaxies is calculated, including the loss of gas due to inhomogeneous cooling. The loss process is modeled as a distributed sink for the gas with the rate of loss being proportional to the local cooling rate. The cooling flow models with gas loss have smaller sonic radii, smaller inflow rates in their central regions, lower densities, and higher temperatures than homogeneous models. The reduction in the amount of hot gas flowing into the center of the models brings the models into much better agreement with the observed X-ray surface brightness profiles of elliptical galaxies. However, there is a large dispersion in the observed X-ray luminosities of ellipticals, and this cannot be explained by variations in the efficiency of gas loss. The gas-loss models have X-ray surface brightness profiles which are much less centrally peaked than the no-gas-loss models.

  16. Study of deformation of droplet in external force field by using liquid-gas model of lattice-gas

    Energy Technology Data Exchange (ETDEWEB)

    Ebihara, Ken-ichi; Watanabe, Tadashi [Japan Atomic Energy Research Inst., Center for Promotion of Computational Science and Engineering, Tokai, Ibaraki (Japan)

    2000-10-01

    The deformation of the droplet by the external force which is assumed to be gravity is studied by using the liquid-gas model of lattice-gas. Two types of liquid-gas models, one is the minimal model and the other is the maximal model, which are distinguished from each other by the added long-range interactions are used for the simulation of the droplet deformation. The difference of the droplet deformation between the maximal model and the minimal model was observed. While the droplet of the minimal model elongates in the direction of the external force, the droplet of the maximal model elongates in the perpendicular direction to the external force. Therefore the droplet deformation in the external force field of the maximal model is more similar to the droplet deformation which is observed in experiments than that of the minimal model. (author)

  17. The modeling of carbon isotope kinetics and its application to the evaluation of natural gas

    Institute of Scientific and Technical Information of China (English)

    Xianqing LI; Xianming XIAO; Yongchun TANG; Hui TIAN; Qiang ZHOU; Yunfeng YANG; Peng DONG; Yan WANG; Zhihong SONG

    2008-01-01

    The modeling of carbon isotope kinetics of natural gas is an issue driving pioneering research in the oil and gas geochemistry in China and internationally.Combined with the sedimentary burial history and basin geothermal history,the modeling of carbon isotope kinetics provides a new and effective means for the determination of the origin and accumulation history of natural gas pools.In this paper,we introduce the modeling of carbon isotope kinetics of natural gas formation and its applications to the assessment of natural gas maturity,the determination of the gas source,the history of gas accumulation,and the oil-gas ratio.It is shown that this approach is of great value for these applications.The carbon isotopic characteristics of natural gas are not only affected by the gas source and maturity of the source rock,but also are related to the accumulation condition and geothermal gradient in a basin.There are obvious differences in the characteristics of carbon isotope ratios between instantaneous gas and cumulative gas.Different basins have different kinetic models of carbon isotope fractionation,which depends on the gas source condition,the accumulation history and the sedimentary-tectonic history.Since the origin of natural gas in the superimposed basin in China is very complicated,and the natural gas pool is characterized by multiphase and variable gas-sources,this paper may provide a new perspective on the study and evaluation of natural gas.

  18. Applications of vortex gas models to tornadogenesis and maintenance

    CERN Document Server

    Bělík, Pavel; Potvin, Corey K; Scholz, Kurt; Shvartsman, Mikhail M

    2016-01-01

    Two-dimensional and three-dimensional vortex gas models are discussed and proposed in this paper as potential models for tornadogenesis and tornado maintenance. The idea of maximization of entropy is utilized which gives rise to negative-temperature systems, in such systems energy is transferred from smaller to larger scales resulting in an inverse energy cascade. In this paper, the smaller scales are represented by intense, supercritical vortices, which transfer energy to the larger-scale tornadic flows. We address the formation of these vortices as a result of the interaction of the flow with the surface and a boundary layer.

  19. Thermodynamic modeling of a gas micro turbine power system; Modelagem termodinamica de uma microturbina a gas

    Energy Technology Data Exchange (ETDEWEB)

    Venson, Giuliano Gardolinski [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Mecanica], e-mail: venson@ufmg.br; Barros, Jose Eduardo Mautone; Pereira, Josemar Figueiredo [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET-MG), Belo Horizonte, MG (Brazil)], e-mail: mautone@des.cefetmg.br, e-mail: josemar_cefet@yahoo.com.br

    2006-07-01

    This work presents the modeling of a gas microturbine power generator. The microturbine consists in a small thermo-electrical power unit, design for combined heat and power generation. The unit has an electric generator, coaxially connected with a turbocharger, which one is driven by a fuel burner. The system also incorporates an air regenerator, used for pre-heat the combustion air, and a heat exchanger, used for water heating. The objective of the modeling is the attainment of the electrical performance and the operational limits for the microturbine in function of the subsystems operational conditions. The modeling is based on the first law of the thermodynamic, using specific models for each component. In the combustion chamber is used a model that takes the fuel injection properties, as absolute pressure and temperature. A semi-empirical model, based in the modified Euler equation, is used in the turbocharger. In the air regenerator and heat exchanger, the method of mean logarithmic temperature difference is used. Through the modeling of a commercial microturbine, reference values obtained were used in some subsystems of a new microturbine. The results for this new microturbine in development, based in automotive turbochargers, indicate a nominal electrical power of 38 kW with electrical efficiency of 33% and global efficiency of 73%. (author)

  20. Natural gas production problems : solutions, methodologies, and modeling.

    Energy Technology Data Exchange (ETDEWEB)

    Rautman, Christopher Arthur; Herrin, James M.; Cooper, Scott Patrick; Basinski, Paul M. (El Paso Production Company, Houston, TX); Olsson, William Arthur; Arnold, Bill Walter; Broadhead, Ronald F. (New Mexico Bureau of Geology and Mineral Resources, Socorro, NM); Knight, Connie D. (Consulting Geologist, Golden, CO); Keefe, Russell G.; McKinney, Curt (Devon Energy Corporation, Oklahoma City, OK); Holm, Gus (Vermejo Park Ranch, Raton, NM); Holland, John F.; Larson, Rich (Vermejo Park Ranch, Raton, NM); Engler, Thomas W. (New Mexico Institute of Mining and Technology, Socorro, NM); Lorenz, John Clay

    2004-10-01

    Natural gas is a clean fuel that will be the most important domestic energy resource for the first half the 21st centtuy. Ensuring a stable supply is essential for our national energy security. The research we have undertaken will maximize the extractable volume of gas while minimizing the environmental impact of surface disturbances associated with drilling and production. This report describes a methodology for comprehensive evaluation and modeling of the total gas system within a basin focusing on problematic horizontal fluid flow variability. This has been accomplished through extensive use of geophysical, core (rock sample) and outcrop data to interpret and predict directional flow and production trends. Side benefits include reduced environmental impact of drilling due to reduced number of required wells for resource extraction. These results have been accomplished through a cooperative and integrated systems approach involving industry, government, academia and a multi-organizational team within Sandia National Laboratories. Industry has provided essential in-kind support to this project in the forms of extensive core data, production data, maps, seismic data, production analyses, engineering studies, plus equipment and staff for obtaining geophysical data. This approach provides innovative ideas and technologies to bring new resources to market and to reduce the overall environmental impact of drilling. More importantly, the products of this research are not be location specific but can be extended to other areas of gas production throughout the Rocky Mountain area. Thus this project is designed to solve problems associated with natural gas production at developing sites, or at old sites under redevelopment.

  1. Optimal control in a micro gas grid of prosumers using Model Predictive Control

    NARCIS (Netherlands)

    Alkano, Desti; Nefkens, W.J.; Scherpen, Jacqueline M.A.; Volkerts, M.

    This paper studies the optimal control of a micro grid of biogas prosumers equipped with local storage devices. Excess biogas can be upgraded and injected into the low- pressure gas grid or, alternatively, shipped per lorry to be used elsewhere in an effort to create revenue. The aim of the control

  2. Optimal control in a micro gas grid of prosumers using Model Predictive Control

    NARCIS (Netherlands)

    Alkano, Desti; Nefkens, W.J.; Scherpen, Jacqueline M.A.; Volkerts, M.

    2014-01-01

    This paper studies the optimal control of a micro grid of biogas prosumers equipped with local storage devices. Excess biogas can be upgraded and injected into the low- pressure gas grid or, alternatively, shipped per lorry to be used elsewhere in an effort to create revenue. The aim of the control

  3. Damage spreading in a driven lattice gas model

    Science.gov (United States)

    Rubio Puzzo, M. Leticia; Saracco, Gustavo P.; Albano, Ezequiel V.

    2013-06-01

    We studied damage spreading in a Driven Lattice Gas (DLG) model as a function of the temperature T, the magnitude of the external driving field E, and the lattice size. The DLG model undergoes an order-disorder second-order phase transition at the critical temperature Tc(E), such that the ordered phase is characterized by high-density strips running along the direction of the applied field; while in the disordered phase one has a lattice-gas-like behavior. It is found that the damage always spreads for all the investigated temperatures and reaches a saturation value D that depends only on T. D increases for TTc(E=∞) and is free of finite-size effects. This behavior can be explained as due to the existence of interfaces between the high-density strips and the lattice-gas-like phase whose roughness depends on T. Also, we investigated damage spreading for a range of finite fields as a function of T, finding a behavior similar to that of the case with E=∞.

  4. Gas modelling in the disc of HD 163296

    CERN Document Server

    Tilling, I; Meeus, G; Mora, A; Montesinos, B; Riviere-Marichalar, P; Eiroa, C; Thi, W -F; Isella, A; Roberge, A; Martin-Zaidi, C; Kamp, I; Pinte, C; Sandell, G; Vacca, W D; Ménard, F; Mendigutía, I; Duchêne, G; Dent, W R F; Aresu, G; Meijerink, R; Spaans, M

    2011-01-01

    We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of ~ 4 Myr, with evidence of a circumstellar disc extending out to ~ 540AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (Gas in Protoplanetary Systems), consisting of a detection of the [OI]63mic line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the 12CO 3-2, 2-1 and 13CO J=1-0 line transitions, as well as the H2 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, ...

  5. Empirical slip and viscosity model performance for microscale gas flows.

    Energy Technology Data Exchange (ETDEWEB)

    Gallis, Michail A.; Boyd, Iain D. (University of Michigan, Ann Arbor, MI); McNenly, Matthew J. (University of Michigan, Ann Arbor, MI)

    2004-07-01

    For the simple geometries of Couette and Poiseuille flows, the velocity profile maintains a similar shape from continuum to free molecular flow. Therefore, modifications to the fluid viscosity and slip boundary conditions can improve the continuum based Navier-Stokes solution in the non-continuum non-equilibrium regime. In this investigation, the optimal modifications are found by a linear least-squares fit of the Navier-Stokes solution to the non-equilibrium solution obtained using the direct simulation Monte Carlo (DSMC) method. Models are then constructed for the Knudsen number dependence of the viscosity correction and the slip model from a database of DSMC solutions for Couette and Poiseuille flows of argon and nitrogen gas, with Knudsen numbers ranging from 0.01 to 10. Finally, the accuracy of the models is measured for non-equilibrium cases both in and outside the DSMC database. Flows outside the database include: combined Couette and Poiseuille flow, partial wall accommodation, helium gas, and non-zero convective acceleration. The models reproduce the velocity profiles in the DSMC database within an L{sub 2} error norm of 3% for Couette flows and 7% for Poiseuille flows. However, the errors in the model predictions outside the database are up to five times larger.

  6. Electro-thermal modeling of a microbridge gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Manginell, R.P.; Smith, J.H.; Ricco, A.J.; Hughes, R.C.; Moreno, D.J. [Sandia National Labs., Albuquerque, NM (United States); Huber, R.J. [Utah Univ., Salt Lake City, UT (United States). Dept. of Electrical Engineering

    1997-08-01

    Fully CMOS-compatible, surface-micromachined polysilicon microbridges have been designed, fabricated, and tested for use in catalytic, calorimetric gas sensing. To improve sensor behavior, extensive electro-thermal modeling efforts were undertaken using SPICE. The validity of the SPICE model was verified comparing its simulated behavior with experiment. Temperature distribution of an electrically heated microbridges was measured using an infrared microscope. Comparisons among the measured distribution, the SPICE simulation, and distributions obtained by analytical methods show that heating at the ends of a microbridges has important implications for device response. Additional comparisons between measured and simulated current-voltage characteristics, as well as transient response, further support the accuracy of the model. A major benefit of electro- thermal modeling with SPICE is the ability to simultaneously simulate the behavior of a device and its control/sensing electronics. Results for the combination of a unique constant-resistance control circuit and microbridges gas sensor are given. Models of in situ techniques for monitoring catalyst deposition are shown to be in agreement with experiment. Finally, simulated chemical response of the detector is compared with the data, and methods of improving response through modifications in bridge geometry are predicted.

  7. Monte Carlo modeling and optimization of buffer gas positron traps

    Science.gov (United States)

    Marjanović, Srđan; Petrović, Zoran Lj

    2017-02-01

    Buffer gas positron traps have been used for over two decades as the prime source of slow positrons enabling a wide range of experiments. While their performance has been well understood through empirical studies, no theoretical attempt has been made to quantitatively describe their operation. In this paper we apply standard models as developed for physics of low temperature collision dominated plasmas, or physics of swarms to model basic performance and principles of operation of gas filled positron traps. The Monte Carlo model is equipped with the best available set of cross sections that were mostly derived experimentally by using the same type of traps that are being studied. Our model represents in realistic geometry and fields the development of the positron ensemble from the initial beam provided by the solid neon moderator through voltage drops between the stages of the trap and through different pressures of the buffer gas. The first two stages employ excitation of N2 with acceleration of the order of 10 eV so that the trap operates under conditions when excitation of the nitrogen reduces the energy of the initial beam to trap the positrons without giving them a chance to become annihilated following positronium formation. The energy distribution function develops from the assumed distribution leaving the moderator, it is accelerated by the voltage drops and forms beams at several distinct energies. In final stages the low energy loss collisions (vibrational excitation of CF4 and rotational excitation of N2) control the approach of the distribution function to a Maxwellian at room temperature but multiple non-Maxwellian groups persist throughout most of the thermalization. Optimization of the efficiency of the trap may be achieved by changing the pressure and voltage drops and also by selecting to operate in a two stage mode. The model allows quantitative comparisons and test of optimization as well as development of other properties.

  8. In vivo tissue specific modulation of rat insulin receptor gene expression in an experimental model of mineralocorticoid excess.

    Science.gov (United States)

    Campión, J; Lahera, V; Cachofeiro, V; Maestro, B; Dávila, N; Carranza, M C; Calle, C

    1998-08-01

    Insulin receptor (IR) gene expression at the mRNA level was investigated in hindlimb skeletal muscle, epididymal adipose tissue and in the liver of rats exposed to prolonged in vivo administration of deoxycorticosterone acetate (DOCA). Following treatment, plasma insulin levels were reduced while glucose levels increased compared to values in control rats. DOCA-treated animals showed an increase in blood pressure and a reduction in body weight. This treatment also induced hypokalemia and decreased plasma protein levels. Sodium levels were unaffected. Moreover, no differences in DNA and protein content or in the indicator of cell size (protein/DNA) were observed in the skeletal muscle or adipose tissue of animals. In contrast, there was a clear increase in the protein and DNA contents of the liver with no change in the indicator of cell size. Northern blot assays revealed 2 major IR mRNA species of approximately 9.5 and 7.5 Kb in the 3 tissues from control animals. DOCA treatment induced no change in the levels of either RNA species in skeletal muscle. However, a decrease of approximately 22% was detected in the levels of both species in adipose tissue whereas the liver showed an increase of 64%. These results provide the first evidence for an in vivo tissue-specific modulation of IR mRNA levels under experimental conditions of mineralocorticoid excess.

  9. Extended models of nonlinear waves in liquid with gas bubbles

    CERN Document Server

    Kudryashov, Nikolay A

    2016-01-01

    In this work we generalize the models for nonlinear waves in a gas--liquid mixture taking into account an interphase heat transfer, a surface tension and a weak liquid compressibility simultaneously at the derivation of the equations for nonlinear waves. We also take into consideration high order terms with respect to the small parameter. Two new nonlinear differential equations are derived for long weakly nonlinear waves in a liquid with gas bubbles by the reductive perturbation method considering both high order terms with respect to the small parameter and the above mentioned physical properties. One of these equations is the perturbation of the Burgers equation and corresponds to main influence of dissipation on nonlinear waves propagation. The other equation is the perturbation of the Burgers--Korteweg--de Vries equation and corresponds to main influence of dispersion on nonlinear waves propagation.

  10. Phase transition with an isospin dependent lattice gas model

    Energy Technology Data Exchange (ETDEWEB)

    Gulminelli, F. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; Chomaz, Ph. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France)

    1998-10-01

    The nuclear liquid-gas phase transition is studied within an isospin dependent Lattice Gas Model in the canonical ensemble. Finite size effects on thermodynamical variables are analyzed by a direct calculation of the partition function, and it is shown that phase coexistence and phase transition are relevant concepts even for systems of a few tens of particles. Critical exponents are extracted from the behaviour of the fragment production yield as a function of temperature by means of a finite size scaling. The result is that in a finite system well defined critical signals can be found at supercritical (Kertesz line) as well as subcritical densities. For isospin asymmetric systems it is shown that, besides the modification of the critical temperature, isotopic distributions can provide an extra observable to identify and characterize the transition. (author) 21 refs.

  11. Sorption Modeling and Verification for Off-Gas Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tavlarides, Lawrence L. [Syracuse Univ., NY (United States); Lin, Ronghong [Syracuse Univ., NY (United States); Nan, Yue [Syracuse Univ., NY (United States); Yiacoumi, Sotira [Georgia Inst. of Technology, Atlanta, GA (United States); Tsouris, Costas [Georgia Inst. of Technology, Atlanta, GA (United States); Ladshaw, Austin [Georgia Inst. of Technology, Atlanta, GA (United States); Sharma, Ketki [Georgia Inst. of Technology, Atlanta, GA (United States); Gabitto, Jorge [Prairie View A & M Univ., Prairie View, TX (United States); DePaoli, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-29

    The project has made progress toward developing a comprehensive modeling capability for the capture of target species in off gas evolved during the reprocessing of nuclear fuel. The effort has integrated experimentation, model development, and computer code development for adsorption and absorption processes. For adsorption, a modeling library has been initiated to include (a) equilibrium models for uptake of off-gas components by adsorbents, (b) mass transfer models to describe mass transfer to a particle, diffusion through the pores of the particle and adsorption on the active sites of the particle, and (c) interconnection of these models to fixed bed adsorption modeling which includes advection through the bed. For single-component equilibria, a Generalized Statistical Thermodynamic Adsorption (GSTA) code was developed to represent experimental data from a broad range of isotherm types; this is equivalent to a Langmuir isotherm in the two-parameter case, and was demonstrated for Kr on INL-engineered sorbent HZ PAN, water sorption on molecular sieve A sorbent material (MS3A), and Kr and Xe capture on metal-organic framework (MOF) materials. The GSTA isotherm was extended to multicomponent systems through application of a modified spreading pressure surface activity model and generalized predictive adsorbed solution theory; the result is the capability to estimate multicomponent adsorption equilibria from single-component isotherms. This advance, which enhances the capability to simulate systems related to off-gas treatment, has been demonstrated for a range of real-gas systems in the literature and is ready for testing with data currently being collected for multicomponent systems of interest, including iodine and water on MS3A. A diffusion kinetic model for sorbent pellets involving pore and surface diffusion as well as external mass transfer has been established, and a methodology was developed for determining unknown diffusivity parameters from transient

  12. The Geopolitical Impact of Shale Gas: The Modelling Approach

    NARCIS (Netherlands)

    Auping, W.L.; De Jong, S.; Pruyt, E.; Kwakkel, J.H.

    2014-01-01

    The US’ shale gas revolution, a spectacular increase in natural gas extraction from previously unconventional sources, has led to considerable lower gas prices in North America. This study focusses on consequences of the shale gas revolution on state stability of traditional oil and gas exporting co

  13. Modeling Circumgalactic Gas During the Peak Epoch of Galaxy Growth

    Science.gov (United States)

    Dave, Romeel

    During the peak of cosmic star formation at z=1-4, galaxy growth is increasingly believed to be modulated by large-scale inflows and outflows of baryons that intimately connect galaxies to their surrounding circumgalactic medium (CGM). Unfortunately, direct observational signatures of these baryon cycling processes are elusive and fragmented, owing to the diffuse and multi- phase nature of the CGM. This proposal aims to use advanced multi-scale cosmological hydrodynamic simulations to investigate how inflows and outflows within circumgalactic gas are manifested in present and future observables, and how those observables in turn constrain the physical processes driving galaxy evolution. The simulation methodology includes ``random" cosmological runs, ``zoom" runs of individual halos, and radiative transfer to better model the ionization conditions. We will focus on absorption and emission signatures in HI and metal lines using common rest-UV and rest-optical tracers. Key questions include: How do metal absorbers trace the enrichment and ionization conditions within circumgalactic gas? How much absorption arises from inflow versus outflow, and what are the characteristic absorption, emission, and/or kinematic signatures of each? What emission lines from CGM gas are predicted to be observable, and how does the combination of emission and absorption constrain CGM properties? What are the roles of metallicity, ionization, and large-scale structure in establishing the correlations of metal absorbers and galaxies on CGM scales? How do all these CGM properties relate to host galaxy properties such as mass, and how do they vary with outflow model? The overall goal is to develop a comprehensive hierarchical-based framework for assembling various observations of circumgalactic gas into a unified scenario for how inflows and outflows govern the growth of galaxies.

  14. Mathematical Modeling of Metal Active Gas (MAG) Arc Welding

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In the present paper, a numerical model for MAG (metal active gas) arc welding of thin plate has been developed. In MAG arc welding, the electrode wire is melted and supplied into the molten pool intermittently. Accordingly, it is assumed on the modeling that the thermal energy enters the base-plates through two following mechanisms, i.e., direct heating from arc plasma and “indirect” heating from the deposited metal. In the second part of the paper, MAG arc welding process is numerically analyzed by using the model, and the calculated weld bead dimension and surface profile have been compared with the experimental MAG welds on steel plate. As the result, it is made clear that the model is capable of predicting the bead profile of thin-plate MAG arc welding , including weld bead with undercutting.

  15. EXPERIMENTAL STUDY AND COMPUTATIONAL MODELLING OF GAS FIRED PULSE COMBUSTION

    Directory of Open Access Journals (Sweden)

    I. Smajevic

    2010-06-01

    Full Text Available The paper presents some results of computational modelling of a gas-fired pulse combustor with aerodynamic valves. The development of the model followed experimental investigations during which the combustor geometry and operating conditions were defined. A simple 'tank and tube' approach was adopted by decomposing the combustor into several elements which were modelled separately, together with the interconnecting processes. The solution was obtained by marching integration in time over several cycles. The model reproduced reasonably well the recorded time history and averaged values of all basic parameters and is expected to complement the experiments aiming to develop a pulse combustor as a device for to cleaning the outer sides of power plants’ boiler heating surfaces during operation.

  16. A complementarity model for the European natural gas market

    Energy Technology Data Exchange (ETDEWEB)

    Egging, Ruud [Department of Civil and Environmental Engineering, University of Maryland College Park, MD 20742 (United States); Gabriel, Steven A. [Department of Civil and Environmental Engineering, Applied Mathematics and Scientific Computation Program, University of Maryland College Park, MD 20742 (United States); Holz, Franziska [DIW Berlin, Mohrenstrasse 58, D-10117 Berlin (Germany); Zhuang, Jifang [Chevron USA, Houston, TX 77401 (United States)

    2008-07-15

    In this paper, we present a detailed and comprehensive complementarity model for computing market equilibrium values in the European natural gas system. Market players include producers and their marketing arms which we call ''traders'', pipeline and storage operators, marketers, LNG liquefiers, regasifiers, tankers, and three end-use consumption sectors. The economic behavior of producers, traders, pipeline and storage operators, liquefiers and regasifiers is modeled via optimization problems whose Karush-Kuhn-Tucker (KKT) optimality conditions in combination with market-clearing conditions form the complementarity system. The LNG tankers, marketers and consumption sectors are modeled implicitly via appropriate cost functions, aggregate demand curves, and ex post calculations, respectively. The model is run on several case studies that highlight its capabilities, including a simulation of a disruption of Russian supplies via Ukraine. (author)

  17. Modeling condensation with a noncondensable gas for mixed convection flow

    Science.gov (United States)

    Liao, Yehong

    2007-05-01

    This research theoretically developed a novel mixed convection model for condensation with a noncondensable gas. The model developed herein is comprised of three components: a convection regime map; a mixed convection correlation; and a generalized diffusion layer model. These components were developed in a way to be consistent with the three-level methodology in MELCOR. The overall mixed convection model was implemented into MELCOR and satisfactorily validated with data covering a wide variety of test conditions. In the development of the convection regime map, two analyses with approximations of the local similarity method were performed to solve the multi-component two-phase boundary layer equations. The first analysis studied effects of the bulk velocity on a basic natural convection condensation process and setup conditions to distinguish natural convection from mixed convection. It was found that the superimposed velocity increases condensation heat transfer by sweeping away the noncondensable gas accumulated at the condensation boundary. The second analysis studied effects of the buoyancy force on a basic forced convection condensation process and setup conditions to distinguish forced convection from mixed convection. It was found that the superimposed buoyancy force increases condensation heat transfer by thinning the liquid film thickness and creating a steeper noncondensable gas concentration profile near the condensation interface. In the development of the mixed convection correlation accounting for suction effects, numerical data were obtained from boundary layer analysis for the three convection regimes and used to fit a curve for the Nusselt number of the mixed convection regime as a function of the Nusselt numbers of the natural and forced convection regimes. In the development of the generalized diffusion layer model, the driving potential for mass transfer was expressed as the temperature difference between the bulk and the liquid-gas interface

  18. Excessive acquisition in hoarding.

    Science.gov (United States)

    Frost, Randy O; Tolin, David F; Steketee, Gail; Fitch, Kristin E; Selbo-Bruns, Alexandra

    2009-06-01

    Compulsive hoarding (the acquisition of and failure to discard large numbers of possessions) is associated with substantial health risk, impairment, and economic burden. However, little research has examined separate components of this definition, particularly excessive acquisition. The present study examined acquisition in hoarding. Participants, 878 self-identified with hoarding and 665 family informants (not matched to hoarding participants), completed an Internet survey. Among hoarding participants who met criteria for clinically significant hoarding, 61% met criteria for a diagnosis of compulsive buying and approximately 85% reported excessive acquisition. Family informants indicated that nearly 95% exhibited excessive acquisition. Those who acquired excessively had more severe hoarding; their hoarding had an earlier onset and resulted in more psychiatric work impairment days; and they experienced more symptoms of obsessive-compulsive disorder, depression, and anxiety. Two forms of excessive acquisition (buying and free things) each contributed independent variance in the prediction of hoarding severity and related symptoms.

  19. Modeling greenhouse gas emissions and nutrient transport in managed arable soils with a fully coupled hydrology-biogeochemical modeling system

    Science.gov (United States)

    Haas, Edwin; Klatt, Steffen; Kiese, Ralf; Butterbach-Bahl, Klaus; Kraft, Philipp; Breuer, Lutz

    2015-04-01

    The use of mineral nitrogen fertilizer sustains the global food production and therefore the livelihood of human kind. The rise in world population will put pressure on the global agricultural system to increase its productivity leading most likely to an intensification of mineral nitrogen fertilizer use. The fate of excess nitrogen and its distribution within landscapes is manifold. Process knowledge on the site scale has rapidly grown in recent years and models have been developed to simulate carbon and nitrogen cycling in managed ecosystems on the site scale. Despite first regional studies, the carbon and nitrogen cycling on the landscape or catchment scale is not fully understood. In this study we present a newly developed modelling approach by coupling the fully distributed hydrology model CMF (catchment modelling framework) to the process based regional ecosystem model LandscapeDNDC for the investigation of hydrological processes and carbon and nitrogen transport and cycling, with a focus on nutrient displacement and resulting greenhouse gas emissions in various virtual landscapes / catchment to demonstrate the capabilities of the modelling system. The modelling system was applied to simulate water and nutrient transport at the at the Yanting Agro-ecological Experimental Station of Purple Soil, Sichuan province, China. The catchment hosts cypress forests on the outer regions, arable fields on the sloping croplands cultivated with wheat-maize rotations and paddy rice fields in the lowland. The catchment consists of 300 polygons vertically stratified into 10 soil layers. Ecosystem states (soil water content and nutrients) and fluxes (evapotranspiration) are exchanged between the models at high temporal scales (hourly to daily) forming a 3-dimensional model application. The water flux and nutrients transport in the soil is modelled using a 3D Richards/Darcy approach for subsurface fluxes with a kinematic wave approach for surface water runoff and the

  20. Gas-Grain Models for Interstellar Anion Chemistry

    Science.gov (United States)

    Cordiner, M. A.; Charnely, S. B.

    2012-01-01

    Long-chain hydrocarbon anions C(sub n) H(-) (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n(sub H2) approx > / cubic cm). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C6H(-) anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C6O, C7O, HC6O, and HC7O, the abundances of which depend on the assumed branching ratios for associative electron detachment

  1. Gas-Grain Models for Interstellar Anion Chemistry

    Science.gov (United States)

    Cordiner, M. A.; Charnely, S. B.

    2012-01-01

    Long-chain hydrocarbon anions C(sub n) H(-) (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n(sub H2) approx > / cubic cm). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C6H(-) anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C6O, C7O, HC6O, and HC7O, the abundances of which depend on the assumed branching ratios for associative electron detachment

  2. Gas turbine cooling modeling - Thermodynamic analysis and cycle simulations

    Energy Technology Data Exchange (ETDEWEB)

    Jordal, Kristin

    1999-02-01

    Considering that blade and vane cooling are a vital point in the studies of modern gas turbines, there are many ways to include cooling in gas turbine models. Thermodynamic methods for doing this are reviewed in this report, and, based on some of these methods, a number of model requirements are set up and a Cooled Gas Turbine Model (CGTM) for design-point calculations of cooled gas turbines is established. Thereafter, it is shown that it is possible to simulate existing gas turbines with the CGTM. Knowledge of at least one temperature in the hot part of the turbine (TET, TRIT or possibly TIT) is found to be vital for a complete heat balance over the turbine. The losses, which are caused by the mixing of coolant and main flow, are in the CGTM considered through a polytropic efficiency reduction factor S. Through the study of S, it can be demonstrated that there is more to gain from coolant reduction in a small and/or old turbine with poor aerodynamics, than there is to gain in a large, modern turbine, where the losses due to interaction between coolant and main flow are, relatively speaking, small. It is demonstrated, at the design point (TET=1360 deg C, {pi}=20) for the simple-cycle gas turbine, that heat exchanging between coolant and fuel proves to have a large positive impact on cycle efficiency, with an increase of 0.9 percentage points if all of the coolant passes through the heat exchanger. The corresponding improvement for humidified coolant is 0.8 percentage points. A design-point study for the HAT cycle shows that if all of the coolant is extracted after the humidification tower, there is a decrease in coolant requirements of 7.16 percentage points, from 19.58% to 12.52% of the compressed air, and an increase in thermal efficiency of 0.46 percentage points, from 53.46% to 53.92%. Furthermore, it is demonstrated with a TET-parameter variation, that the cooling of a simple-cycle gas turbine with humid air can have a positive effect on thermal efficiency

  3. Oil and gas supply and economics model for Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Partowidagdo, W.

    1987-01-01

    The central goal of this study was to estimate the potential of Indonesia's unexplored basins to continue to provide income to the country. Specific objectives were: (1) Build a model that estimates how the level of efforts by the contractors in a basin will vary as physical properties, government's tax rate, and hydrocarbon prices vary. The basic assumption underlying the model is that a contractor adapts his efforts in an attempt to maximize his discounted profit. (2) Use the model to analyze the impact of the Government's tax policy in each Indonesian basin. The model consists of three submodels: discovery, development and economics. The main program uses these three submodels iteratively to determine optimum investment, which give maximum net revenue for the contractors, as a function of tax rate and hydrocarbon price for each basin in Indonesia. Remaining recoverable reserves up to the contractors' economic limit and to government's economic limit were calculated for each of the 40 known basins in Indonesia. As expected, the following conditions cause calculated recoverables to increase: (1) higher hydrocarbon prices; (2) higher fraction of discovered gas developed and sold; (3) lower cost in a basin; (a) less remote area, (b) shallower sea, (c) shallower formation; (4) higher fraction of oil in a basin (oil is more profitable than gas).

  4. CFD model of a spinning pipe gas lens

    CSIR Research Space (South Africa)

    Snedden, Glen C

    2006-07-01

    Full Text Available Slides on: Spinning Pipe Gas Lens; Focal Length; Refractive Index; Gas Dynamics; Guess at the gas dynamics; Density Profile; Flow Profile; Rosby Waves; Rayleigh–Taylor Instabilities...

  5. Externally Fired micro-Gas Turbine: Modelling and experimental performance

    Energy Technology Data Exchange (ETDEWEB)

    Traverso, Alberto; Massardo, Aristide F. [Thermochemical Power Group, Dipartimento di Macchine, Sistemi Energetici e Trasporti, Universita di Genova, Genova (Italy); Scarpellini, Riccardo [Ansaldo Ricerche s.r.l., Genova (Italy)

    2006-11-15

    This work presents the steady-state and transient performance obtained by an Externally Fired micro-Gas Turbine (EFmGT) demonstration plant. The plant was designed by Ansaldo Ricerche (ARI) s.r.l. and the Thermochemical Power Group (TPG) of the Universita di Genova, using the in-house TPG codes TEMP (Thermoeconomic Modular Program) and TRANSEO. The plant was based on a recuperated 80kW micro-gas turbine (Elliott TA-80R), which was integrated with the externally fired cycle at the ARI laboratory. The first goal of the plant construction was the demonstration of the EFmGT control system. The performance obtained in the field can be improved in the near future using high-temperature heat exchangers and apt external combustors, which should allow the system to operate at the actual micro-gas turbine inlet temperature (900-950{sup o}C). This paper presents the plant layout and the control system employed for regulating the microturbine power and rotational speed. The experimental results obtained by the pilot plant in early 2004 are shown: the feasibility of such a plant configuration has been demonstrated, and the control system has successfully regulated the shaft speed in all the tests performed. Finally, the plant model in TRANSEO, which was formerly used to design the control system, is shown to accurately simulate the plant behaviour both at steady-state and transient conditions. (author)

  6. Modeling cast IN-738 superalloy gas tungsten arc welds

    Energy Technology Data Exchange (ETDEWEB)

    Bonifaz, E.A. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, E2-327F EITC, Winnipeg, Man., R3T 5V6 (Canada); Universidad San Francisco de Quito, Casilla Postal: 17-12-841 Circulo de Cumbaya, Quito (Ecuador)], E-mail: bonifaz@cc.umanitoba.ca; Richards, N.L. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, E2-327F EITC, Winnipeg, Man., R3T 5V6 (Canada)], E-mail: nrichar@cc.umanitoba.ca

    2009-04-15

    A three-dimensional finite-element thermal model has been developed to generate weld profiles, and to analyze transient heat flow, thermal gradients and thermal cycles in cast IN-738 superalloy gas tungsten arc welds. Outputs of the model (cooling rates, the thermal gradient G and the growth rate R) were used to describe solidification structures found around the weld pool for three different welding speeds at constant heat input. Calculations around the weld pool indicate that the cooling rate increases from the fusion line to the centerline at all welding speeds. It was also observed that the cooling rate (G x R) and the ratio G/R fall with welding speed. For instance, as the welding speed is increased, the cooling rates at the centerline, fusion line and penetration depth decrease. Moreover, it was observed that as the power and welding speed both increase (but keeping the heat input constant), the weld pool becomes wider and more elongated, shifting from circular to elliptical shaped. The calculations were performed using ABAQUS FE code on the basis of a time-increment Lagrangian formulation. The heat source represented by a moving Gaussian power density distribution is applied over the top surface of the specimen during a period of time that depends on the welding speed. Temperature-dependent material properties and the effect of forced convection due to the flow of the shielding gas are included in the model. Numerically predicted sizes of the melt-pool zone and dendrite secondary arm spacing induced by the gas tungsten arc welding process are also given.

  7. Jet fire consequence modeling for high-pressure gas pipelines

    Science.gov (United States)

    Coccorullo, Ivano; Russo, Paola

    2016-12-01

    A simple and reliable approach for sizing the hazard area potentially affected by a jet fire as consequence of the failure of high-pressure pipeline is proposed. A release rate model, taking pipeline operation properties and source release properties into account, is coupled with SLAB dispersion model and point source radiation model to calculate the hazard distance. The hazard distance is set beyond the distance at which a low chance of fatality can occur to people exposed and a wooden structure is not expected to burn due to radiation heat of jet fire. The comparison between three gases with different physico-chemical properties (i.e. natural gas, hydrogen, ethylene) is shown. The influence of pipeline operating parameters, such as: pressure, pipeline diameter and length, hole size, on the hazard area for the three gases is evaluated. Finally, a simple correlation is proposed for calculating the hazard distance as function of these parameters.

  8. On The Modelling Of Hybrid Aerostatic - Gas Journal Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2011-01-01

    Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...... modeling for hybrid lubrication of a compressible fluid film journal bearing. Additional forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving...

  9. Study on Turbulent Modeling in Gas Entrainment Evaluation Method

    Science.gov (United States)

    Ito, Kei; Ohshima, Hiroyuki; Nakamine, Yoshiaki; Imai, Yasutomo

    Suppression of gas entrainment (GE) phenomena caused by free surface vortices are very important to establish an economically superior design of the sodium-cooled fast reactor in Japan (JSFR). However, due to the non-linearity and/or locality of the GE phenomena, it is not easy to evaluate the occurrences of the GE phenomena accurately. In other words, the onset condition of the GE phenomena in the JSFR is not predicted easily based on scaled-model and/or partial-model experiments. Therefore, the authors are developing a CFD-based evaluation method in which the non-linearity and locality of the GE phenomena can be considered. In the evaluation method, macroscopic vortex parameters, e.g. circulation, are determined by three-dimensional CFD and then, GE-related parameters, e.g. gas core (GC) length, are calculated by using the Burgers vortex model. This procedure is efficient to evaluate the GE phenomena in the JSFR. However, it is well known that the Burgers vortex model tends to overestimate the GC length due to the lack of considerations on some physical mechanisms. Therefore, in this study, the authors develop a turbulent vortex model to evaluate the GE phenomena more accurately. Then, the improved GE evaluation method with the turbulent viscosity model is validated by analyzing the GC lengths observed in a simple experiment. The evaluation results show that the GC lengths analyzed by the improved method are shorter in comparison to the original method, and give better agreement with the experimental data.

  10. Self-similarity of phase-space networks of frustrated spin models and lattice gas models

    Science.gov (United States)

    Peng, Yi; Wang, Feng; Han, Yilong

    2013-03-01

    We studied the self-similar properties of the phase-spaces of two frustrated spin models and two lattice gas models. The frustrated spin models included (1) the anti-ferromagnetic Ising model on a two-dimensional triangular lattice (1a) at the ground states and (1b) above the ground states and (2) the six-vertex model. The two lattice gas models were (3) the one-dimensional lattice gas model and (4) the two-dimensional lattice gas model. The phase spaces were mapped to networks so that the fractal analysis of complex networks could be applied, i.e. the box-covering method and the cluster-growth method. These phase spaces, in turn, establish new classes of networks with unique self-similar properties. Models 1a, 2, and 3 with long-range power-law correlations in real space exhibit fractal phase spaces, while models 1b and 4 with short-range exponential correlations in real space exhibit nonfractal phase spaces. This behavior agrees with one of untested assumptions in Tsallis nonextensive statistics. Hong Kong GRC grants 601208 and 601911

  11. Variable-mass Thermodynamics Calculation Model for Gas-operated Automatic Weapon%Variable-mass Thermodynamics Calculation Model for Gas-operated Automatic Weapon

    Institute of Scientific and Technical Information of China (English)

    陈建彬; 吕小强

    2011-01-01

    Aiming at the fact that the energy and mass exchange phenomena exist between barrel and gas-operated device of the automatic weapon, for describing its interior ballistics and dynamic characteristics of the gas-operated device accurately, a new variable-mass thermodynamics model is built. It is used to calculate the automatic mechanism velocity of a certain automatic weapon, the calculation results coincide with the experimental results better, and thus the model is validated. The influences of structure parameters on gas-operated device' s dynamic characteristics are discussed. It shows that the model is valuable for design and accurate performance prediction of gas-operated automatic weapon.

  12. Transient multiphase flow modeling of gas well liquid loading

    NARCIS (Netherlands)

    Veeken, K.; Hu, B.; Schiferli, W.

    2009-01-01

    Gas well liquid loading occurs when gas production becomes insufficient to lift the associated liquids to surface. When that happens gas production first turns intermittent and eventually stops. Hence in depleting gas reservoirs the technical abandonment pressure and ultimate recovery are typically

  13. Operational modeling of a sustainable gas supply chain

    NARCIS (Netherlands)

    Bekkering, Jan; Broekhuis, Ton A; van Gemert, Wim J. T.

    2010-01-01

    Biogas production from codigestion of cattle manure and biomass can have a significant contribution to a sustainable gas supply when this gas is upgraded to specifications prescribed for injection into the national gas grid and injected into this grid. In this study, we analyzed such a gas supply ch

  14. Operational modeling of a sustainable gas supply chain

    NARCIS (Netherlands)

    Bekkering, Jan; Broekhuis, Ton A; van Gemert, Wim J. T.

    2010-01-01

    Biogas production from codigestion of cattle manure and biomass can have a significant contribution to a sustainable gas supply when this gas is upgraded to specifications prescribed for injection into the national gas grid and injected into this grid. In this study, we analyzed such a gas supply

  15. Natural gas and blends oxidation and ignition: Experiments and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Y.; Dagaut, P.; Cathonnet, M.; Boettner, J.C. [CNRS, Orleans (France); Bachman, J.S.; Carlier, P. [Gaz de France, La Plaine-Saint-Denis (France)

    1994-12-31

    The kinetics of the oxidation of natural gas and blends (CH{sub 4}/C{sub 2}H{sub 6}, CH{sub 4}/C{sub 3}H{sub 8}, CH{sub 4}/C{sub 2}H{sub 6}/C{sub 3}H{sub 8}) has been studied in a jet-stirred reactor (800 {<=} T/K {<=} 1240, 1 {<=} P/atm {<=} 10, 0.1 {<=} equivalence ratio {<=} 1.5). The concentration profiles of reactants, intermediates, and products measured in a jet-stirred reactor (JSR) have been used to validate a detailed kinetic reaction mechanism. Literature ignition delay times measured in shock tube have also been modeled. A generally good agreement between the data and the model is found. The same mechanism has also been used to successfully represent the oxidation of methane, ethyne, ethene, ethane, propene, propane, n-butane, and 1-butene in various conditions including JSR, shock tube, and flame. The present study clearly shows the importance of trace hydrocarbons in the oxidation of methane. The computations indicate that the oxidation of methane is initiated by its reaction with O{sub 2} when no other hydrocarbon is present. In natural gas and blends, higher hydrocarbons react before methane, leading to the formation of OH, H, and O radicals, which in turn initiate methane oxidation. This work demonstrates that methane cannot be used safely to represent the kinetics of natural gas combustion. However, simple blends like methane-propane or methane-ethane-propane could be used.

  16. Advanced modeling of oxy-fuel combustion of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Chungen Yin

    2011-01-15

    The main goal of this small-scale project is to investigate oxy-combustion of natural gas (NG) through advanced modeling, in which radiation, chemistry and mixing will be reasonably resolved. 1) A state-of-the-art review was given regarding the latest R and D achievements and status of oxy-fuel technology. The modeling and simulation status and achievements in the field of oxy-fuel combustion were also summarized; 2) A computer code in standard c++, using the exponential wide band model (EWBM) to evaluate the emissivity and absorptivity of any gas mixture at any condition, was developed and validated in detail against data in literature. A new, complete, and accurate WSGGM, applicable to both air-fuel and oxy-fuel combustion modeling and applicable to both gray and non-gray calculation, was successfully derived, by using the validated EWBM code as the reference mode. The new WSGGM was implemented in CFD modeling of two different oxy-fuel furnaces, through which its great, unique advantages over the currently most widely used WSGGM were demonstrated. 3) Chemical equilibrium calculations were performed for oxy-NG flame and air-NG flame, in which dissociation effects were considered to different degrees. Remarkable differences in oxy-fuel and air-fuel combustion were revealed, and main intermediate species that play key roles in oxy-fuel flames were identified. Different combustion mechanisms are compared, e.g., the most widely used 2-step global mechanism, refined 4-step global mechanism, a global mechanism developed for oxy-fuel using detailed chemical kinetic modeling (CHEMKIN) as reference. 4) Over 15 CFD simulations were done for oxy-NG combustion, in which radiation, chemistry, mixing, turbulence-chemistry interactions, and so on were thoroughly investigated. Among all the simulations, RANS combined with 2-step and refined 4-step mechanism, RANS combined with CHEMKIN-based new global mechanism for oxy-fuel modeling, and LES combined with different combustion

  17. Excessive cytosolic DNA fragments as a potential trigger of Graves’ disease: an encrypted message sent by animal models

    Directory of Open Access Journals (Sweden)

    Yuqian Luo

    2016-11-01

    Full Text Available Graves’ hyperthyroidism is caused by autoantibodies directed against the thyroid stimulating hormone receptor (TSHR that mimic the action of TSH. The establishment of Graves’ hyperthyroidism in experimental animals has proven to be an important approach to dissect the mechanisms of self-tolerance breakdown that lead to the production of thyroid-stimulating TSHR autoantibodies (TSAbs. ‘Shimojo’s model was the first successful Graves’ animal model, wherein immunization with fibroblasts cells expressing TSHR and a major histocompatibility complex (MHC class II molecule, but not either alone, induced TSAb production in AKR/N (H-2k mice. This model highlights the importance of coincident MHC class II expression on TSHR-expressing cells in the development of Graves’ hyperthyroidism. These data are also in agreement with the observation that Graves’ thyrocytes often aberrantly express MHC class II antigens via mechanisms that remain unclear. Our group demonstrated that cytosolic self-genomic DNA fragments derived from sterile injured cells can induce aberrant MHC class II expression and production of multiple inflammatory cytokines and chemokines in thyrocytes in vitro, suggesting that severe cell injury may initiate immune responses in a way that is relevant to thyroid autoimmunity mediated by cytosolic DNA signaling. Furthermore, more recent successful Graves’ animal models were primarily established by immunizing mice with TSHR-expressing plasmids or adenovirus. In these models, double-stranded DNA vaccine contents presumably exert similar immune-activating effect in cells at inoculation sites and thus might pave the way toward successful Graves’ animal models. This review focuses on evidence suggesting that cell injury-derived self-DNA fragments could act as Graves’ disease triggers.

  18. Bidirectional enantioselective effects of the GABAB receptor agonist baclofen in two mouse models of excessive ethanol consumption.

    Science.gov (United States)

    Kasten, Chelsea R; Blasingame, Shelby N; Boehm, Stephen L

    2015-02-01

    The GABAB receptor agonist baclofen has been studied extensively in preclinical models of alcohol-use disorders, yet results on its efficacy have been uncertain. Racemic baclofen, which is used clinically, can be broken down into separate enantiomers of the drug. Baclofen has been shown to produce enantioselective effects in behavioral assays, including those modeling reflexive and sexual behavior. The current studies sought to characterize the enantioselective effects of baclofen in two separate models of ethanol consumption. The first was a Drinking-in-the-Dark procedure that provides "binge-like" ethanol access to mice by restricting access to a 2-h period, 3 h into the dark cycle. The second was a two-bottle choice procedure that utilized selectively bred High Alcohol Preferring 1 (HAP1) mice to model chronic ethanol access. HAP1 mice are selectively bred to consume pharmacologically relevant amounts of ethanol in a 24-h two-bottle choice paradigm. The results showed that baclofen yields enantioselective effects on ethanol intake in both models, and that these effects are bidirectional. Total ethanol intake was decreased by R(+)-baclofen, while total intake was increased by S(-)-baclofen in the binge-like and chronic drinking models. Whereas overall binge-like saccharin intake was significantly reduced by R(+)-baclofen, chronic intake was not significantly altered. S(-)-baclofen did not significantly alter saccharin intake. Neither enantiomer significantly affected locomotion during binge-like reinforcer consumption. Collectively, these results demonstrate that baclofen produces enantioselective effects on ethanol consumption. More importantly, the modulation of consumption is bidirectional. The opposing enantioselective effects may explain some of the variance seen in published baclofen literature.

  19. Nahoon: Time-dependent gas-phase chemical model

    Science.gov (United States)

    Wakelam, V.

    2014-09-01

    Nahoon is a gas-phase chemical model that computes the chemical evolution in a 1D temperature and density structure. It uses chemical networks downloaded from the KInetic Database for Astrochemistry (KIDA) but the model can be adapted to any network. The program is written in Fortran 90 and uses the DLSODES (double precision) solver from the ODEPACK package to solve the coupled stiff differential equations. The solver computes the chemical evolution of gas-phase species at a fixed temperature and density and can be used in one dimension (1D) if a grid of temperature, density, and visual extinction is provided. Grains, both neutral and negatively charged, and electrons are considered as chemical species and their concentrations are computed at the same time as those of the other species. Nahoon contains a test to check the temperature range of the validity of the rate coefficients and avoid extrapolations outside this range. A test is also included to check for duplication of chemical reactions, defined over complementary ranges of temperature.

  20. Analytical model of neutral gas shielding for hydrogen pellet ablation

    Energy Technology Data Exchange (ETDEWEB)

    Kuteev, Boris V.; Tsendin, Lev D. [State Technical Univ., St. Petersburg (Russian Federation)

    2001-11-01

    A kinetic gasdynamic scaling for hydrogen pellet ablation is obtained in terms of a neural gas shielding model using both numerical and analytical approaches. The scaling on plasma and pellet parameters proposed in the monoenergy approximation by Milora and Foster dR{sub pe}/dt{approx}S{sub n}{sup 2/3}R{sub p}{sup -2/3}q{sub eo}{sup 1/3}m{sub i}{sup -1/3} is confirmed. Here R{sub p} is the pellet radius, S{sub n} is the optical thickness of a cloud, q{sub eo} is the electron energy flux density and m{sub i} is the molecular mass. Only the numeral factor is approximately two times less than that for the monoenergy approach. Due to this effect, the pellet ablation rates, which were obtained by Kuteev on the basis of the Milora scaling, should be reduced by a factor of 1.7. Such a modification provides a reasonable agreement (even at high plasma parameters) between the two-dimensional kinetic model and the one-dimensional monoenergy approximation validated in contemporary tokamak experiments. As the could (in the kinetic approximation) is significantly thicker than that for the monoenergy case as well as the velocities of the gas flow are much slower, the relative effect of plasma and magnetic shielding on the ablation rate is strongly reduced. (author)

  1. A Model for Gas Microporosity in Aluminum and Magnesium Alloys

    Science.gov (United States)

    Felicelli, Sergio D.; Wang, Liang; Pita, Claudio M.; Escobar de Obaldia, Enrique

    2009-04-01

    A quantitative prediction of the amount of gas microporosity in aluminum and magnesium-alloy castings is performed with a continuum model of dendritic solidification. The distribution of the pore volume fraction and pore size is calculated from a set of conservation equations that solves the transport phenomena during solidification at the macroscale and the hydrogen diffusion into the pores at the microscale. A technique based on a pseudo-alloy solute that is transported by the melt is used to determine the potential sites of pore growth, subject to considerations of mechanical and thermodynamic equilibrium. The modeling results for aluminum alloy A356 are found to agree well with published studies. In view of the limited availability of experimental data for Mg-alloy gravity-poured castings, the formation of porosity in AZ91 is studied qualitatively, assuming that casting conditions are similar to A356. In particular, the minimum initial hydrogen content that leads to the formation of gas porosity was compared for both alloys. It is found that the initial hydrogen content necessary for forming porosity is much higher in AZ91 than in A356. This is attributed to significant differences in the solubility of the hydrogen in both alloys.

  2. Dynamic-structure-factor measurements on a model Lorentz gas

    Science.gov (United States)

    Egelstaff, P. A.; Eder, O. J.; Glaser, W.; Polo, J.; Renker, B.; Soper, A. K.

    1990-02-01

    A model system for the Lorentz gas can be made [Eder, Chen, and Egelstaff, Proc. Phys. Soc. London 89, 833 (1966); McPherson and Egelstaff, Can. J. Phys. 58, 289 (1980)] by mixing small quantities of hydrogen with an argon host. For neutron-scattering experiments the large H-to-Ar cross section ratio (~200) makes the argon relatively invisible. Dynamic-structure-factor [S(Q,ω) for H2] measurements at room temperature have been made on this system using the IN4 spectrometer at the Institute Laue Langevin, Grenoble, France. Argon densities between 1.9 and 10.5 atoms/nm3 were used for 0.4gas host at densities of 4 and 10.5 atoms/nm3; helium is relatively invisible also compared to hydrogen. These experiments are described, and some examples of the results are presented to show the qualitative effects observed. The principle observation is a pronounced narrowing of S(Q,ω) as a function of ω as the argon density is increased. This effect is large at low Q and decreases with increasing Q, and also decreases substantially when helium is used in place of argon. In addition, the shape of S(Q,ω) is more complex than can be accommodated within a simple model, but slightly less complicated than a computer simulation so showing the significance of multiple-collision processes.

  3. An electricity price model with consideration to load and gas price effects

    Institute of Scientific and Technical Information of China (English)

    黄民翔; 陶小虎; 韩祯祥

    2003-01-01

    Some characteristics of the electricity load and prices are studied, and the relationship between electricity prices and gas (fuel) prices is analyzed in this paper. Because electricity prices are strongly dependent on load and gas prices, the authors constructed a model for electricity prices based on the effects of these two factors; and used the Geometric Mean Reversion Brownian Motion (GMRBM) model to describe the electricity load process, and a Geometric Brownian Motion(GBM) model to describe the gas prices; deduced the price stochastic process model based on the above load model and gas price model. This paper also presents methods for parameters estimation, and proposes some methods to solve the model.

  4. Development and application of an efficient gas extraction model for low-rank high-gas coal beds

    Institute of Scientific and Technical Information of China (English)

    Baiquan Lin; He Li; Desheng Yuan; Ziwen Li

    2015-01-01

    To promote gas extraction in low-rank high-gas coal beds, the pore structure characteristics of the coal and their effect on gas desorption were studied. The results show that micropores are relatively rare in low-rank coal;mesopores are usually semi-open and inkpot-shaped whereas macropores are usually slit-shaped. Gas desorption is relatively easy at high-pressure stages, whereas it is difficult at low-pressure stages because of the‘bottleneck effect’ of the semi-open inkpot-shaped mesopores. A ‘two-three-two’ gas extraction model was established following experimental analysis and engi-neering practice applied in the Binchang mining area. In this model, gas extraction is divided into three periods:a planning period, a transitional period and a production period. In each period, surface extraction and underground extraction are performed simultaneously, and pressure-relief extraction and conventional extraction are coupled to each other. After applying this model, the gas extraction rate rose to 78.8%.

  5. CFD modelling of longwall goaf gas flow to improve gas capture and prevent goaf self-heating

    Institute of Scientific and Technical Information of China (English)

    REN Ting-xiang

    2009-01-01

    CFD models have been developed to investigate the Iongwall goaf gas flow pat-terns under different mining and geological control conditions. The Iongwall goaf was treated as porous regions and gas flow was modelled as a momentum sink added to the momentum equation. Gas desorption from the caved goaf and destressed coal seams within the mining disturbed area was modelled as additional mass sources in the continu-ity equation. These CFD models were developed according to specific Iongwall layouts and calibrated against field monitoring data. Two case studies were presented demon-strating the application of CFD modelling of goaf gas flow characteristics for improved goaf gas capture and the reduction of oxygen ingress into the goaf areas for self-heating pre-vention. Results from the case studies indicate that the optimum goaf drainage strategy would be a combination of shallow (near the face) and deep holes to improve the overall drainage efficiency and gas purity. For gassy longwall faces retreating against the seam dip, it is recommended to conduct cross-measure roof hole drainage targeting the fractured zones overlying the return comer, rather than high capacity surface goaf drainage deep in the goaf.

  6. Breakdown parameter for kinetic modeling of multiscale gas flows.

    Science.gov (United States)

    Meng, Jianping; Dongari, Nishanth; Reese, Jason M; Zhang, Yonghao

    2014-06-01

    Multiscale methods built purely on the kinetic theory of gases provide information about the molecular velocity distribution function. It is therefore both important and feasible to establish new breakdown parameters for assessing the appropriateness of a fluid description at the continuum level by utilizing kinetic information rather than macroscopic flow quantities alone. We propose a new kinetic criterion to indirectly assess the errors introduced by a continuum-level description of the gas flow. The analysis, which includes numerical demonstrations, focuses on the validity of the Navier-Stokes-Fourier equations and corresponding kinetic models and reveals that the new criterion can consistently indicate the validity of continuum-level modeling in both low-speed and high-speed flows at different Knudsen numbers.

  7. First cosmological constraints on the Superfluid Chaplygin gas model

    CERN Document Server

    Lazkoz, Ruth; Salzano, Vincenzo

    2012-01-01

    In this work we set observational constraints of the Superfluid Chaplygin gas model, which gives a unified description of the dark sector of the Universe as a Bose-Einstein condensate (BEC) that behaves as dark energy (DE) while it is in the ground state and as dark matter (DM) when it is in the excited state. We first show and perform the various steps leading to a form of the equations suitable for the observational tests to be carried out. Then, by using a Markov Chain Monte Carlo (MCMC) code, we constrain the model with a sample of cosmology-independent long gamma-ray bursts (LGRBs) calibrated using their Type I Fundamental Plane, as well as the Union2.1 set and observational Hubble parameter data. In this analysis, using our cosmological constraints, we sketch the effective equation of state parameter and deceleration parameter, and we also obtain the redshift of the transition from deceleration to acceleration: $z_t$.

  8. Modified Chaplygin gas inspired inflationary model in braneworld scenario

    Science.gov (United States)

    Jawad, Abdul; Rani, Shamaila; Mohsaneen, Sidra

    2016-05-01

    We investigate the modified Chaplygin gas inspired inflationary regime in the brane-world framework in the presence of standard and tachyon scalar fields. We consider the intermediate inflationary scenario and construct the slow-roll parameters, e-folding numbers, spectral index, scalar and tensor power spectra, tensor to scalar ratio for both scalar field models. We develop the ns - N and r - N planes and concluded that ns˜eq96^{+0.5}_{-0.5} and r≤0.0016 for N˜eq60^{+5}_{-5} in both cases of scalar field models as well as for all values of m. These constraints are consistent with observational data such as WMAP7, WMAP9 and Planck data.

  9. iCRESLIDE: Integration of Coupled Routing and Excess Storage and SLope-Infiltration-Distributed Equilibrium for the Cascading Hydrologic-Geotechnical Modeling

    Science.gov (United States)

    Hong, Y.; Zhang, K.; Gourley, J. J.

    2015-12-01

    Floods and landslides account for the large number of natural hazards and affect more people than many other types of natural disasters around the world. This study proposed a coupled hydrological-geotechnical model iCRESLIDE (Integration of Coupled Routing and Excess Storage and SLope-Infiltration-Distributed Equilibrium). The iCRESLIDE is designed to remedy the discrepancy of the original landslide model (SLIDE) by coupling with a hydrological model (CREST) and building an integrated system for predicting cascading storm-flood-landslides using remote sensing and geospatial datasets. This coupled system is implemented and evaluated in Macon County, North Carolina, where Hurricane Ivan triggered widespread landslides in September 2004 during the hurricane season. Model simulations from iCRESLIDE show its reliability to predict landslides occurrence (location and time). Receiver Operating Characteristic (ROC) analysis demonstrate that the iCRESLIDE has higher global accuracy (0.750) and higher sensitivity (11.36%) compared to the original SLIDE model. Such improved predictive performance demonstrates the advantage of coupling hydrological-geotechnical models, which calls more attentions and deserves further investigations in order to develop a not only geotechnical sound but also hydrological sensitive system for landslides early warning at regional scale. This talk will also present early results of the NFL (National-Flash-Landslide) Monitoring and Prediction system under development at the NOAA/OU National Weather Center.

  10. Parameter tolerance to forcing data, case study of Coupled Routing and Excess STorage (CREST) hydrological model in Head region of Yellow River of China

    Science.gov (United States)

    Li, Li; Wang, Jiahu; Hao, Zhenchun

    2010-05-01

    Most of the hydrological models need be calibrated based on the gauged runoff at the catchment outlet. Calibration is a process that optimizing parameters to get the best reproduction of nature runoff for certain forcing data. This means different forcing data could result in similar simulation after calibration, it is called parameter tolerance to forcing data in this paper. This study chooses head region of Yellow River of China as an example, uses the CREST (Coupled Routing and Excess STorage distributed model) for hydrological simulation and ARS (Adaptive Random Search algorithm) for deriving parameters automatically, evaluates the response of forcing data fluctuation after calibration; compares three different forcing data sets: station gauge, TRMM-based Multi-satellite Precipitation Analysis (TMPA) calibration rainfall data (3B42V6) and Real-Time rainfall data (3B42RT), and their simulations after calibrated separately. Results indicate that most of the forcing data fluctuation can be eliminated by parameter optimization until model collapse for extreme input. Considering parameter tolerance to forcing data, TRMMV6 is better than station gauge for its strong point in spatial description, and difference between TRMMV6 and TRMMRT in driving CREST is tiny. These results could vary in other basins or models, further comparison between basins and models is recommended. Keywords: Hydrological modeling; Parameter; forcing data; CREST; Automated calibration

  11. Anyonic behavior of an intermediate-statistics fermion gas model.

    Science.gov (United States)

    Algin, Abdullah; Irk, Dursun; Topcu, Gozde

    2015-06-01

    We study the high-temperature behavior of an intermediate-statistics fermionic gas model whose quantum statistical properties enable us to effectively deduce the details about both the interaction among deformed (quasi)particles and their anyonic behavior. Starting with a deformed fermionic grand partition function, we calculate, in the thermodynamical limit, several thermostatistical functions of the model such as the internal energy and the entropy by means of a formalism of the fermionic q calculus. For high temperatures, a virial expansion of the equation of state for the system is obtained in two and three dimensions and the first five virial coefficients are derived in terms of the model deformation parameter q. From the results obtained by the effect of fermionic deformation, it is found that the model parameter q interpolates completely between bosonlike and fermionic systems via the behaviors of the third and fifth virial coefficients in both two and three spatial dimensions and in addition it characterizes effectively the interaction among quasifermions. Our results reveal that the present deformed (quasi)fermion model could be very efficient and effective in accounting for the nonlinear behaviors in interacting composite particle systems.

  12. Natural gas transmission and distribution model of the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-02-01

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of Integrated Analysis and Forecasting of the Energy Information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. From 1982 through 1993, the Intermediate Future Forecasting System (IFFS) was used by the EIA for its analyses, and the Gas Analysis Modeling System (GAMS) was used within IFFS to represent natural gas markets. Prior to 1982, the Midterm Energy Forecasting System (MEFS), also referred to as the Project Independence Evaluation System (PIES), was employed. NEMS was developed to enhance and update EIA`s modeling capability by internally incorporating models of energy markets that had previously been analyzed off-line. In addition, greater structural detail in NEMS permits the analysis of a broader range of energy issues. The time horizon of NEMS is the midterm period (i.e., through 2015). In order to represent the regional differences in energy markets, the component models of NEMS function at regional levels appropriate for the markets represented, with subsequent aggregation/disaggregation to the Census Division level for reporting purposes.

  13. A paradigm for modeling and computation of gas dynamics

    Science.gov (United States)

    Xu, Kun; Liu, Chang

    2017-02-01

    In the continuum flow regime, the Navier-Stokes (NS) equations are usually used for the description of gas dynamics. On the other hand, the Boltzmann equation is applied for the rarefied flow. These two equations are based on distinguishable modeling scales for flow physics. Fortunately, due to the scale separation, i.e., the hydrodynamic and kinetic ones, both the Navier-Stokes equations and the Boltzmann equation are applicable in their respective domains. However, in real science and engineering applications, they may not have such a distinctive scale separation. For example, around a hypersonic flying vehicle, the flow physics at different regions may correspond to different regimes, where the local Knudsen number can be changed significantly in several orders of magnitude. With a variation of flow physics, theoretically a continuous governing equation from the kinetic Boltzmann modeling to the hydrodynamic Navier-Stokes dynamics should be used for its efficient description. However, due to the difficulties of a direct modeling of flow physics in the scale between the kinetic and hydrodynamic ones, there is basically no reliable theory or valid governing equations to cover the whole transition regime, except resolving flow physics always down to the mean free path scale, such as the direct Boltzmann solver and the Direct Simulation Monte Carlo (DSMC) method. In fact, it is an unresolved problem about the exact scale for the validity of the NS equations, especially in the small Reynolds number cases. The computational fluid dynamics (CFD) is usually based on the numerical solution of partial differential equations (PDEs), and it targets on the recovering of the exact solution of the PDEs as mesh size and time step converging to zero. This methodology can be hardly applied to solve the multiple scale problem efficiently because there is no such a complete PDE for flow physics through a continuous variation of scales. For the non-equilibrium flow study, the direct

  14. Modeling of Gas Production from Shale Reservoirs Considering Multiple Transport Mechanisms

    Science.gov (United States)

    Guo, Chaohua; Wei, Mingzhen; Liu, Hong

    2015-01-01

    Gas transport in unconventional shale strata is a multi-mechanism-coupling process that is different from the process observed in conventional reservoirs. In micro fractures which are inborn or induced by hydraulic stimulation, viscous flow dominates. And gas surface diffusion and gas desorption should be further considered in organic nano pores. Also, the Klinkenberg effect should be considered when dealing with the gas transport problem. In addition, following two factors can play significant roles under certain circumstances but have not received enough attention in previous models. During pressure depletion, gas viscosity will change with Knudsen number; and pore radius will increase when the adsorption gas desorbs from the pore wall. In this paper, a comprehensive mathematical model that incorporates all known mechanisms for simulating gas flow in shale strata is presented. The objective of this study was to provide a more accurate reservoir model for simulation based on the flow mechanisms in the pore scale and formation geometry. Complex mechanisms, including viscous flow, Knudsen diffusion, slip flow, and desorption, are optionally integrated into different continua in the model. Sensitivity analysis was conducted to evaluate the effect of different mechanisms on the gas production. The results showed that adsorption and gas viscosity change will have a great impact on gas production. Ignoring one of following scenarios, such as adsorption, gas permeability change, gas viscosity change, or pore radius change, will underestimate gas production. PMID:26657698

  15. Modeling of Gas Production from Shale Reservoirs Considering Multiple Transport Mechanisms.

    Directory of Open Access Journals (Sweden)

    Chaohua Guo

    Full Text Available Gas transport in unconventional shale strata is a multi-mechanism-coupling process that is different from the process observed in conventional reservoirs. In micro fractures which are inborn or induced by hydraulic stimulation, viscous flow dominates. And gas surface diffusion and gas desorption should be further considered in organic nano pores. Also, the Klinkenberg effect should be considered when dealing with the gas transport problem. In addition, following two factors can play significant roles under certain circumstances but have not received enough attention in previous models. During pressure depletion, gas viscosity will change with Knudsen number; and pore radius will increase when the adsorption gas desorbs from the pore wall. In this paper, a comprehensive mathematical model that incorporates all known mechanisms for simulating gas flow in shale strata is presented. The objective of this study was to provide a more accurate reservoir model for simulation based on the flow mechanisms in the pore scale and formation geometry. Complex mechanisms, including viscous flow, Knudsen diffusion, slip flow, and desorption, are optionally integrated into different continua in the model. Sensitivity analysis was conducted to evaluate the effect of different mechanisms on the gas production. The results showed that adsorption and gas viscosity change will have a great impact on gas production. Ignoring one of following scenarios, such as adsorption, gas permeability change, gas viscosity change, or pore radius change, will underestimate gas production.

  16. Models for grains and gas ejection dynamics from a silo

    Science.gov (United States)

    Zhou, Yixian; Aussillous, Pascale; Ruyer, Pierre; Iusti/Gep Team; Semia/Limar Team

    2015-11-01

    In the hypothetical conditions of a reactivity initiated accident in a nuclear power plant, some of the fuel rods could break. If fuel fragmentation occurs, hot fuel particles and pressurized gas could interact with the surrounding fluid. The violence of this interaction depends on the discharge rate toward the fluid. In the present work, we study the discharge dynamics and identify the parameters governing this flow. In this paper, we focus on the experimental study of the discharge of a silo composed of spherical glass beads, with an orifice either lateral or at the bottom, with or without air flow. The measured parameters are the mass flow rate and the pressure along the silo, whereas the controlled parameters are the size of particles, the size of orifices, and the flow rate of air. For the case without air flow we found that the flow rate of particles ejected from the bottom orifice is 3 times greater than from the lateral orifice. For the case of a lateral orifice, when the form of the orifice is rectangular with width W and height D, we identify two regimes which depend on the ratio of width to height W / D . For the case with air flow, we found that the flow rate increases with the air flow. A simple physical model is proposed to describe the grains and gas ejection.

  17. Effects of gas types and models on optimized gas fuelling station reservoir's pressure

    OpenAIRE

    M. Farzaneh-Gord; M. Deymi-Dashtebayaz; Rahbari,H. R.

    2013-01-01

    There are similar algorithms and infrastructure for storing gas fuels at CNG (Compressed Natural Gas) and CHG (Compressed Hydrogen Gas) fuelling stations. In these stations, the fuels are usually stored in the cascade storage system to utilize the stations more efficiently. The cascade storage system generally divides into three reservoirs, commonly termed low, medium and high-pressure reservoirs. The pressures within these reservoirs have huge effects on performance of the stations. In the c...

  18. Greenhouse Gas Source Attribution: Measurements Modeling and Uncertainty Quantification

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhen [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Safta, Cosmin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sargsyan, Khachik [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Najm, Habib N. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); van Bloemen Waanders, Bart Gustaaf [Sandia National Lab. (SNL-CA), Livermore, CA (United States); LaFranchi, Brian W. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Ivey, Mark D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Schrader, Paul E. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Michelsen, Hope A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Bambha, Ray P. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2014-09-01

    In this project we have developed atmospheric measurement capabilities and a suite of atmospheric modeling and analysis tools that are well suited for verifying emissions of green- house gases (GHGs) on an urban-through-regional scale. We have for the first time applied the Community Multiscale Air Quality (CMAQ) model to simulate atmospheric CO2 . This will allow for the examination of regional-scale transport and distribution of CO2 along with air pollutants traditionally studied using CMAQ at relatively high spatial and temporal resolution with the goal of leveraging emissions verification efforts for both air quality and climate. We have developed a bias-enhanced Bayesian inference approach that can remedy the well-known problem of transport model errors in atmospheric CO2 inversions. We have tested the approach using data and model outputs from the TransCom3 global CO2 inversion comparison project. We have also performed two prototyping studies on inversion approaches in the generalized convection-diffusion context. One of these studies employed Polynomial Chaos Expansion to accelerate the evaluation of a regional transport model and enable efficient Markov Chain Monte Carlo sampling of the posterior for Bayesian inference. The other approach uses de- terministic inversion of a convection-diffusion-reaction system in the presence of uncertainty. These approaches should, in principle, be applicable to realistic atmospheric problems with moderate adaptation. We outline a regional greenhouse gas source inference system that integrates (1) two ap- proaches of atmospheric dispersion simulation and (2) a class of Bayesian inference and un- certainty quantification algorithms. We use two different and complementary approaches to simulate atmospheric dispersion. Specifically, we use a Eulerian chemical transport model CMAQ and a Lagrangian Particle Dispersion Model - FLEXPART-WRF. These two models share the same WRF

  19. A coupling model for gas diffusion and seepage in SRV section of shale gas reservoirs

    Directory of Open Access Journals (Sweden)

    Shusheng Gao

    2017-03-01

    Full Text Available A prerequisite to effective shale gas development is a complicated fracture network generated by extensive and massive fracturing, which is called SRV (stimulated reservoir volume section. Accurate description of gas flow behaviors in such section is fundamental for productivity evaluation and production performance prediction of shale gas wells. The SRV section is composed of bedrocks with varying sizes and fracture networks, which exhibit different flow behaviors – gas diffusion in bedrocks and gas seepage in fractures. According to the porosity and permeability and the adsorption, diffusion and seepage features of bedrocks and fractures in a shale gas reservoir, the material balance equations were built for bedrocks and fractures respectively and the continuity equations of gas diffusion and seepage in the SRV section were derived. For easy calculation, the post-frac bedrock cube was simplified to be a sphere in line with the principle of volume consistency. Under the assumption of quasi-steady flow behavior at the cross section of the sphere, the gas channeling equation was derived based on the Fick's laws of diffusion and the density function of gas in bedrocks and fractures. The continuity equation was coupled with the channeling equation to effectively characterize the complicated gas flow behavior in the SRV section. The study results show that the gas diffusivity in bedrocks and the volume of bedrocks formed by volume fracturing (or the scale of fracturing jointly determines the productivity and stable production period of a shale gas well. As per the actual calculation for the well field A in the Changning–Weiyuan Block in the Sichuan Basin, the matrix has low gas diffusivity – about 10−5 cm2/s and a large volume with an equivalent sphere radius of 6.2 m, hindering the gas channeling from bedrocks to fractures and thereby reducing the productivity of the shale gas well. It is concluded that larger scale of volume fracturing

  20. Modeling of diffuse molecular gas applied to HD 102065 observations

    CERN Document Server

    Nehme, Cyrine; Boulanger, Francois; Forets, Guillaume Pineau des; Gry, Cecile

    2008-01-01

    Aims. We model a diffuse molecular cloud present along the line of sight to the star HD 102065. We compare our modeling with observations to test our understanding of physical conditions and chemistry in diffuse molecular clouds. Methods. We analyze an extensive set of spectroscopic observations which characterize the diffuse molecular cloud observed toward HD 102065. Absorption observations provide the extinction curve, H2, C I, CO, CH, and CH+ column densities and excitation. These data are complemented by observations of CII, CO and dust emission. Physical conditions are determined using the Meudon PDR model of UV illuminated gas. Results. We find that all observational results, except column densities of CH, CH+ and H2 in its excited (J > 2) levels, are consistent with a cloud model implying a Galactic radiation field (G~0.4 in Draine's unit), a density of 80 cm-3 and a temperature (60-80 K) set by the equilibrium between heating and cooling processes. To account for excited (J >2) H2 levels column densit...

  1. Observational constraints on new generalized Chaplygin gas model

    CERN Document Server

    Liao, Kai; Zhu, Zong-Hong

    2012-01-01

    We use the latest data to investigate observational constraints on the new generalized Chaplygin gas (NGCG) model. Using the Markov Chain Monte Carlo (MCMC) method, we constrain the NGCG model with the type Ia supernovae (SNe Ia) from Union2 set (557 data), the usual baryonic acoustic oscillation (BAO) observation from the spectroscopic Sloan Digital Sky Survey (SDSS) data release 7 (DR7) galaxy sample, the cosmic microwave background (CMB) observation from the 7-year Wilkinson Microwave Anisotropy Probe (WMAP7) results, the newly revised $H(z)$ data, as well as a value of $\\theta_{BAO} (z=0.55) = (3.90 \\pm 0.38)^{\\circ}$ for the angular BAO scale. The constraint results for NGCG model are $\\omega_X = -1.0510_{-0.1685}^{+0.1563}(1\\sigma)_{-0.2398}^{+0.2226}(2\\sigma)$, $\\eta = 1.0117_{-0.0502}^{+0.0469}(1\\sigma)_{-0.0716}^{+0.0693}(2\\sigma)$, and $\\Omega_X = 0.7297_{-0.0276}^{+0.0229}(1\\sigma)_{-0.0402}^{+0.0329}(2\\sigma)$, which give a rather stringent constraint. From the results, we can see a phantom model ...

  2. Modified Chaplygin gas as an interacting holographic dark energy model

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The modified Chaplygin gas (MCG) as an interacting model of holographic dark energy in which dark energy and dark matter are coupled together is investigated in this paper. Concretely, by studying the evolutions of related cosmological quantities such as density parameter Ω, equation of state w, deceleration parameter q and transition redshift zT, we find the evolution of the universe is from deceleration to acceleration, their present values are consistent with the latest observations, and the equation of state of holographic dark energy can cross the phantom divide w = -1. Furthermore, we put emphasis upon the geometrical diagnostics for our model, i.e., the statefinder and Om diagnostics. By illustrating the evolutionary trajectories in r - s, r - q, w -w and Om planes, we find that the holographic constant c and the coupling constant b play very important roles in the holographic dark energy (HDE) model. In addition, we also plot the LCDM horizontal lines in Om diagrams, and show the discrimination between the HDE and LCDM models.

  3. Observational constraints on the new generalized Chaplygin gas model

    Institute of Scientific and Technical Information of China (English)

    Kai Liao; Yu Pan; Zong-Hong Zhu

    2013-01-01

    We use the latest data to investigate observational constraints on the new generalized Chaplygin gas (NGCG) model.Using the Markov Chain Monte Carlo method,we constrain the NGCG model with type Ⅰa supernovae from the Union2 set (557 data),the usual baryonic acoustic oscillation (BAO) observation from the spectroscopic Sloan Digital Sky Survey data release 7 galaxy sample,the cosmic microwave background observation from the 7-year Wilkinson Microwave Anisotropy Probe results,newly revised data on H(z),as well as a value of θBAO (z =0.55) =(3.90° ± 0.38°) for the angular BAO scale.The constraint results for the NGCG model are ωx=-1.0510(-0.1685)(+0.1563)(1σ)(-0.2398)(+0.2226)(2σ),η=1.0117(-0.0502)(+0.0469)(1σ)(-0.0716)(+0.0693)(2σ) and Ωx=0.7297(-0.0276)(+0.0229)(1σ)(-0.0402)(+0.0329)(2σ),which give a rather stringent constraint.From the results,we can see that a phantom model is slightly favored and the proba-bility that energy transfers from dark matter to dark energy is a little larger than the inverse.

  4. Highly covariant quantum lattice gas model of the Dirac equation

    CERN Document Server

    Yepez, Jeffrey

    2011-01-01

    We revisit the quantum lattice gas model of a spinor quantum field theory-the smallest scale particle dynamics is partitioned into unitary collide and stream operations. The construction is covariant (on all scales down to a small length {\\ell} and small time {\\tau} = c {\\ell}) with respect to Lorentz transformations. The mass m and momentum p of the modeled Dirac particle depend on {\\ell} according to newfound relations m = mo cos (2{\\pi}{\\ell}/{\\lambda}) and p = (h/2{\\pi}{\\ell}) sin(2{\\pi}{\\ell}/{\\lambda}), respectively, where {\\lambda} is the Compton wavelength of the modeled particle. These relations represent departures from a relativistically invariant mass and the de Broglie relation-when taken as quantifying numerical errors the model is physically accurate when {\\ell} {\\ll} {\\lambda}. Calculating the vacuum energy in the special case of a massless spinor field, we find that it vanishes (or can have a small positive value) for a sufficiently large wave number cutoff. This is a marked departure from th...

  5. MELCOR Model Development of High Temperature Gas-cooled Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Changyong; Huh, Changwook [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2013-05-15

    The High Temperature Gas-cooled Reactor is one of the major challenging issues on the development of licensing technology for HTGR. The safety evaluation tools of HTGR can be developed in two ways - development of new HTGR-specific codes or revision of existing codes. The KINS is considering using existing analytic tools to the extent feasible, with appropriate modifications for the intended purpose. The system-level MELCOR code is traditionally used for LWR safety analysis, which is capable of performing thermal-fluid and accident analysis, including fission-product transport and release. Recently, this code is being modified for the NGNP HTGR by the NRC. In this study, the MELCOR input model for HTGR with Reactor Cavity Cooling System (RCCS) was developed and the steady state performance was analyzed to evaluate the applicability in HTGR. HTGR model with design characteristics of GT-MHR was developed using MELCOR 2.1 code to validate the applicability of MELCOR code to HTGR. In addition, the steady state of GT-MHR was analyzed with the developed model. It was evaluated to predict well the design parameters of GT-MHR. The developed model can be used as the basis for accident analysis of HTGR with further update of packages such as Radio Nuclide (RN) package.

  6. Estimating the economic value of ice climbing in Hyalite Canyon: An application of travel cost count data models that account for excess zeros.

    Science.gov (United States)

    Anderson, D Mark

    2010-01-01

    Recently, the sport of ice climbing has seen a dramatic increase in popularity. This paper uses the travel cost method to estimate the demand for ice climbing in Hyalite Canyon, Montana, one of the premier ice climbing venues in North America. Access to Hyalite and other ice climbing destinations have been put at risk due to liability issues, public land management agendas, and winter road conditions. To this point, there has been no analysis on the economic benefits of ice climbing. In addition to the novel outdoor recreation application, this study applies econometric methods designed to deal with "excess zeros" in the data. Depending upon model specification, per person per trip values are estimated to be in the range of $76 to $135.

  7. Field scale geomechanical modeling for prediction of fault stability during underground gas storage operations in a depleted gas field in the Netherlands

    NARCIS (Netherlands)

    Orlic, B.; Wassing, B.B.T.; Geel, C.R.

    2013-01-01

    A geomechanical modeling study was conducted to investigate stability of major faults during past gas production and future underground gas storage operations in a depleted gas field in the Netherlands. The field experienced induced seismicity during gas production, which was most likely caused by

  8. Field scale geomechanical modeling for prediction of fault stability during underground gas storage operations in a depleted gas field in the Netherlands

    NARCIS (Netherlands)

    Orlic, B.; Wassing, B.B.T.; Geel, C.R.

    2013-01-01

    A geomechanical modeling study was conducted to investigate stability of major faults during past gas production and future underground gas storage operations in a depleted gas field in the Netherlands. The field experienced induced seismicity during gas production, which was most likely caused by t

  9. Nonaccommodative convergence excess.

    Science.gov (United States)

    von Noorden, G K; Avilla, C W

    1986-01-15

    Nonaccommodative convergence excess is a condition in which a patient has orthotropia or a small-angle esophoria or esotropia at distance and a large-angle esotropia at near, not significantly reduced by the addition of spherical plus lenses. The AC/A ratio, determined with the gradient method, is normal or subnormal. Tonic convergence is suspected of causing the convergence excess in these patients. Nonaccommodative convergence excess must be distinguished from esotropia with a high AC/A ratio and from hypoaccommodative esotropia. In 24 patients treated with recession of both medial recti muscles with and without posterior fixation or by posterior fixation alone, the mean correction of esotropia was 7.4 prism diopters at distance and 17 prism diopters at near.

  10. Excessive crying in infants

    Directory of Open Access Journals (Sweden)

    Ricardo Halpern

    2016-06-01

    Full Text Available ABSTRACT Objective: Review the literature on excessive crying in young infants, also known as infantile colic, and its effects on family dynamics, its pathophysiology, and new treatment interventions. Data source: The literature review was carried out in the Medline, PsycINFO, LILACS, SciELO, and Cochrane Library databases, using the terms “excessive crying,” and “infantile colic,” as well technical books and technical reports on child development, selecting the most relevant articles on the subject, with emphasis on recent literature published in the last five years. Summary of the findings: Excessive crying is a common symptom in the first 3 months of life and leads to approximately 20% of pediatric consultations. Different prevalence rates of excessive crying have been reported, ranging from 14% to approximately 30% in infants up to 3 months of age. There is evidence linking excessive crying early in life with adaptive problems in the preschool period, as well as with early weaning, maternal anxiety and depression, attention deficit hyperactivity disorder, and other behavioral problems. Several pathophysiological mechanisms can explain these symptoms, such as circadian rhythm alterations, central nervous system immaturity, and alterations in the intestinal microbiota. Several treatment alternatives have been described, including behavioral measures, manipulation techniques, use of medication, and acupuncture, with controversial results and effectiveness. Conclusion: Excessive crying in the early months is a prevalent symptom; the pediatrician's attention is necessary to understand and adequately manage the problem and offer support to exhausted parents. The prescription of drugs of questionable action and with potential side effects is not a recommended treatment, except in extreme situations. The effectiveness of dietary treatments and use of probiotics still require confirmation. There is incomplete evidence regarding alternative

  11. Modelling internal air systems in gas turbine engines

    Institute of Scientific and Technical Information of China (English)

    J Michael Owen

    2007-01-01

    Rotating-disc systems can be used to model,experimentally and computationally,the flow and heat transfer that occur inside the internal cooling-air systems of gas turbine engines.These rotating-disc systems have been used successfully to simplify and understand some of the complex flows that occur in internal-air systems,and designers have used this insight to improve the cooling effectiveness,thereby increasing the engine efficiency and reducing the emissions.In this review paper,three important cases are considered:hot-gas ingress;the pre-swirl system;and buoyancy-induced flow.Ingress,or ingestion,occurs when hot gas from the mainstream gas path is ingested into the wheel-space between the turbine disc and its adjacent casing.Rim seals are fitted at the periphery of the system,and sealing flow is used to reduce or prevent ingress.However,too much sealing air reduces the engine efficiency,and too little can cause serious overheating,resulting in damage to the turbine rim and blade roots.Although the flow is three-dimensional and unsteady,there are encouraging signs that simple 'orifice models' could be used to estimate the amount of ingress into the wheel-space.In a pre-swirl system,the cooling air for the gas-turbine blades is swirled by stationary nozzles,and the air is delivered to the blades via receiver holes in the rotating turbine disc.Swirling the air reduces its temperature relative to the rotating blades,and the designer needs to calculate the air temperature and pressure drop in the system.The designer also needs to calculate the effect of this swirling flow on the heat transfer from the turbine disc to the air,as this has a significant effect on the temperature distribution and stresses in the disc.Recent experimental and computational studies have given a better understanding of the flow and heat transfer in these systems.Buoyancy-induced flow occurs in the cavity between two co-rotating compressor discs when the temperature of the discs is higher

  12. New model of work of the gas-turbine engine

    Directory of Open Access Journals (Sweden)

    В.М. Дихановський

    2004-04-01

    Full Text Available  Problem questions of the gas-turbine engines exploitation are analysed. It is shown, that the gas-mechanics regulation of aerodynamic profile attack corner theorem allowed to design the regulation of the axial compressor system. This system is ability to provide reliable functioning of the gas-turbine engine at any service conditions.

  13. Stochastic method for modeling of the rarefied gas transport coefficients

    Science.gov (United States)

    Rudyak, V. Ya; Lezhnev, E. V.

    2016-08-01

    In this paper, we propose an algorithm for computation of the transport coefficients of rarefied gas, which is based on stochastic modeling of phase trajectories considered molecular system. The hard spheres potential is used. The number of operations is proportional to the number of used molecules. Naturally in this algorithm the conservation laws are performed. The efficiency of the algorithm is demonstrated by the calculation of the viscosity and diffusion coefficients of several noble gases (argon, neon, xenon, krypton). It was shown that the algorithm accuracy of the order of 1-2% can be obtained by using a relatively small number of molecules. The accuracy dependence on the number of used molecules, statistics (number of the used phase trajectories) and calculation time was analyzed.

  14. Pseudo-particle modeling for gas flow in microchannels

    Institute of Scientific and Technical Information of China (English)

    WANG LiMin; GE Wei; CHEN FeiGuo

    2007-01-01

    The velocity profiles and temperature distributions of gas flow in microchannels, for Knudsen numbers ranging from 0.01 to 0.20, are investigated with pseudo-particle modeling (PPM). It has been found that the velocity profiles are mainly affected by Knudsen number and the external force fields applied. When Knudsen number was increased, the slip velocities on the walls increased at the beginning, and then decreased. The temperature distributions were also significantly affected by the external force. The Darcy friction factor increased with increasing Knudsen number, and its variation with Mach number under increased Knudsen number was similar to the so-called premature laminar-turbulent transition observed in experiments.

  15. Modeling of air-gas and dynamic processes in driving development workings in the gas-bearing coal seams

    Energy Technology Data Exchange (ETDEWEB)

    Presler, V.T. [Russian Academy of Science, Kemerovo (Russian Federation). Siberian Branch, Inst. of Coal & Coal Fuel Chemistry

    2002-04-01

    The models for air-gas processes of different hierarchical level are considered in designing and driving development workings in the coal seams. The procedure is proposed for model adaptation according to the on-line data, which makes it possible to estimate the state of medium and working capacity of measuring equipment.

  16. Multiscale model reduction for shale gas transport in fractured media

    KAUST Repository

    Akkutlu, I. Y.

    2016-05-18

    In this paper, we develop a multiscale model reduction technique that describes shale gas transport in fractured media. Due to the pore-scale heterogeneities and processes, we use upscaled models to describe the matrix. We follow our previous work (Akkutlu et al. Transp. Porous Media 107(1), 235–260, 2015), where we derived an upscaled model in the form of generalized nonlinear diffusion model to describe the effects of kerogen. To model the interaction between the matrix and the fractures, we use Generalized Multiscale Finite Element Method (Efendiev et al. J. Comput. Phys. 251, 116–135, 2013, 2015). In this approach, the matrix and the fracture interaction is modeled via local multiscale basis functions. In Efendiev et al. (2015), we developed the GMsFEM and applied for linear flows with horizontal or vertical fracture orientations aligned with a Cartesian fine grid. The approach in Efendiev et al. (2015) does not allow handling arbitrary fracture distributions. In this paper, we (1) consider arbitrary fracture distributions on an unstructured grid; (2) develop GMsFEM for nonlinear flows; and (3) develop online basis function strategies to adaptively improve the convergence. The number of multiscale basis functions in each coarse region represents the degrees of freedom needed to achieve a certain error threshold. Our approach is adaptive in a sense that the multiscale basis functions can be added in the regions of interest. Numerical results for two-dimensional problem are presented to demonstrate the efficiency of proposed approach. © 2016 Springer International Publishing Switzerland

  17. Modelling and Identification for Control of Gas Bearings

    DEFF Research Database (Denmark)

    Theisen, Lukas Roy Svane; Niemann, Hans Henrik; Santos, Ilmar

    2015-01-01

    Gas bearings are popular for their high speed capabilities, low friction and clean operation, but suffer from poor damping, which poses challenges for safe operation in presence of disturbances. Enhanced damping can be achieved through active lubrication techniques using feedback control laws...... to industrial rotating machinery with gas bearings and to allow for subsequent control design. The paper shows how piezoelectric actuators in a gas bearing are efficiently used to perturb the gas film for identification over relevant ranges of rotational speed and gas injection pressure. Parameter...

  18. Monte Carlo model for electron degradation in xenon gas

    CERN Document Server

    Mukundan, Vrinda

    2016-01-01

    We have developed a Monte Carlo model for studying the local degradation of electrons in the energy range 9-10000 eV in xenon gas. Analytically fitted form of electron impact cross sections for elastic and various inelastic processes are fed as input data to the model. Two dimensional numerical yield spectrum, which gives information on the number of energy loss events occurring in a particular energy interval, is obtained as output of the model. Numerical yield spectrum is fitted analytically, thus obtaining analytical yield spectrum. The analytical yield spectrum can be used to calculate electron fluxes, which can be further employed for the calculation of volume production rates. Using yield spectrum, mean energy per ion pair and efficiencies of inelastic processes are calculated. The value for mean energy per ion pair for Xe is 22 eV at 10 keV. Ionization dominates for incident energies greater than 50 eV and is found to have an efficiency of 65% at 10 keV. The efficiency for the excitation process is 30%...

  19. Kinetic model on coke oven gas with steam reforming

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jia-yuan; ZHOU Jie-min; YAN Hong-jie

    2008-01-01

    The effects of factors such as the molar ratio of H2O to CH4 (n(H2O)/n(CH4)), methane conversion temperature and time on methane conversion rate were investigated to build kinetic model for reforming of coke-oven gas with steam. The results of experiments show that the optimal conditions for methane conversion are that the molar ratio of H2O to CH4 varies from 1.1 to 1.3and the conversion temperature varies from 1 223 to 1 273 K. The methane conversion rate is more than 95% when the molar ratio ofH2O to CH4 is 1.2, the conversion temperature is above 1 223 K and the conversion time is longer than 0.75 s. Kinetic model of methane conversion was proposed. All results demonstrate that the calculated values by the kinetic model accord with the experimental data well, and the error is less than 1.5%.

  20. Thermodynamic and Process Modelling of Gas Hydrate Systems in CO2 Capture Processes

    DEFF Research Database (Denmark)

    Herslund, Peter Jørgensen

    A novel gas separation technique based on gas hydrate formation (solid precipitation) is investigated by means of thermodynamic modeling and experimental investigations. This process has previously been proposed for application in post-combustion carbon dioxide capture from power station flue gas...

  1. HIV Excess Cancers JNCI

    Science.gov (United States)

    In 2010, an estimated 7,760 new cancers were diagnosed among the nearly 900,000 Americans known to be living with HIV infection. According to the first comprehensive study in the United States, approximately half of these cancers were in excess of what wo

  2. Model of coupled gas flow and deformation process in heterogeneous coal seams and its application

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chun-hui; ZHAO Quan-sheng; YU Yong-jiang

    2011-01-01

    The heterogeneity of coal was studied by mechanical tests. Probability plots of experimental data show that the mechanical parameters of heterogeneous coal follow a Weibull distribution. Based on elasto-plastic mechanics and gas dynamics, the model of coupled gas flow and deformation process of heterogeneous coal was presented and the effects of heterogeneity of coal on gas flow and failure of coal were investigated. Major findings include: The effect of the heterogeneity of coal on gas flow and mechanical failure of coal can be considered by the model in this paper. Failure of coal has a great effect on gas flow.

  3. The Cosmic Ray Electron Excess

    Science.gov (United States)

    Chang, J.; Adams, J. H.; Ahn, H. S.; Bashindzhagyan, G. L.; Christl, M.; Ganel, O.; Guzik, T. G.; Isbert, J.; Kim, K. C.; Kuznetsov, E. N.; Panasyuk, M. I.; Panov, A. D.; Schmidt, W. K. H.; Seo, E. S.; Sokolskaya, N. V.; Watts, J. W.; Wefel, J. P.; Wu, J.; Zatsepin, V. I.

    2008-01-01

    This slide presentation reviews the possible sources for the apparent excess of Cosmic Ray Electrons. The presentation reviews the Advanced Thin Ionization Calorimeter (ATIC) instrument, the various parts, how cosmic ray electrons are measured, and shows graphs that review the results of the ATIC instrument measurement. A review of Cosmic Ray Electrons models is explored, along with the source candidates. Scenarios for the excess are reviewed: Supernova remnants (SNR) Pulsar Wind nebulae, or Microquasars. Each of these has some problem that mitigates the argument. The last possibility discussed is Dark Matter. The Anti-Matter Exploration and Light-nuclei Astrophysics (PAMELA) mission is to search for evidence of annihilations of dark matter particles, to search for anti-nuclei, to test cosmic-ray propagation models, and to measure electron and positron spectra. There are slides explaining the results of Pamela and how to compare these with those of the ATIC experiment. Dark matter annihilation is then reviewed, which represent two types of dark matter: Neutralinos, and kaluza-Kline (KK) particles, which are next explained. The future astrophysical measurements, those from GLAST LAT, the Alpha Magnetic Spectrometer (AMS), and HEPCAT are reviewed, in light of assisting in finding an explanation for the observed excess. Also the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) could help by revealing if there are extra dimensions.

  4. Diphoton Excess through Dark Mediators

    CERN Document Server

    Chen, Chien-Yi; Pospelov, Maxim; Zhong, Yi-Ming

    2016-01-01

    Preliminary ATLAS and CMS results from the first 13 TeV LHC run have encountered an intriguing excess of events in the diphoton channel around the invariant mass of 750 GeV. We investigate a possibility that the current excess is due to a heavy resonance decaying to light metastable states, which in turn give displaced decays to very highly collimated $e^+e^-$ pairs. Such decays may pass the photon selection criteria, and successfully mimic the diphoton events, especially at low counts. We investigate two classes of such models, characterized by the following underlying production and decay chains: $gg \\to S\\to A'A'\\to (e^+e^-)(e^+e^-)$ and $q\\bar q \\to Z' \\to sa\\to (e^+e^-)(e^+e^-)$, where at the first step a heavy scalar, $S$, or vector, $Z'$, resonances are produced that decay to light metastable vectors, $A'$, or (pseudo-)scalars, $s$ and $a$. Setting the parameters of the models to explain the existing excess, and taking the ATLAS detector geometry into account, we marginalize over the properties of heav...

  5. The \\textit{Fermi}-LAT gamma-ray excess at the Galactic Center in the singlet-doublet fermion dark matter model

    CERN Document Server

    Horiuchi, Shunsaku; Restrepo, Diego; Rivera, Andres; Silverwood, Hamish; Zapata, Oscar

    2016-01-01

    The singlet-doublet fermion dark matter model (SDFDM) provides a good DM candidate as well as the possibility of generating neutrino masses radiatively. The search and identification of DM requires the combined effort of both indirect and direct DM detection experiments in addition to the LHC. Remarkably, an excess of GeV gamma rays from the Galactic Center (GCE) has been measured with the \\textit{Fermi} Large Area Telescope (LAT) which appears to be robust with respect to changes in the diffuse galactic background modeling. Although several astrophysical explanations have been proposed, DM remains a simple and well motivated alternative. In this work, we examine the sensitivities of dark matter searches in the SDFDM scenario using \\textit{Fermi}-LAT, CTA, IceCube/DeepCore, LUX, PICO and LHC with an emphasis on exploring the regions of the parameter space that can account for the GCE. We find that DM particles present in this model with masses close to $\\sim 99$ GeV and $\\sim (173-190)$ GeV annihilating predo...

  6. Armodafinil and modafinil in patients with excessive sleepiness associated with shift work disorder: a pharmacokinetic/pharmacodynamic model for predicting and comparing their concentration-effect relationships.

    Science.gov (United States)

    Darwish, Mona; Bond, Mary; Ezzet, Farkad

    2012-09-01

    Armodafinil, the longer lasting R-isomer of racemic modafinil, improves wakefulness in patients with excessive sleepiness associated with shift work disorder (SWD). Pharmacokinetic studies suggest that armodafinil achieves higher plasma concentrations than modafinil late in a dose interval following equal oral doses. Pooled Multiple Sleep Latency Test (MSLT) data from 2 randomized, double-blind, placebo-controlled trials in 463 patients with SWD, 1 with armodafinil 150 mg/d and 1 with modafinil 200 mg/d (both administered around 2200 h before night shifts), were used to build a pharmacokinetic/pharmacodynamic model. Predicted plasma drug concentrations were obtained by developing and applying a population pharmacokinetic model using nonlinear mixed-effects modeling. Armodafinil 200 mg produced a plasma concentration above the EC(50) (4.6 µg/mL) for 9 hours, whereas modafinil 200 mg did not exceed the EC(50). Consequently, armodafinil produced greater increases in predicted placebo-subtracted MSLT times of 0.5-1 minute (up to 10 hours after dosing) compared with modafinil. On a milligram-to-milligram basis, armodafinil 200 mg consistently increased wakefulness more than modafinil 200 mg, including times late in the 8-hour shift.

  7. 超额赔款再保险的双Cox风险模型%A Couple Cox Risk Model about Excess of Loss Reinsurance

    Institute of Scientific and Technical Information of China (English)

    洪圣光; 赵秀青

    2012-01-01

    With the expansion and development of insurance business,insurance companies must purchase reinsurance of certain types of insurance to avoid the risk.To study the ruin probability of the insurance company after purchasing the reinsurance,a couple Cox risk model about excess of loss reinsurance is discussed in the paper.In the model,occurrence of claims and receiving of premiums are described by the Cox process.The paper gets an un-bound of ruin probability about the model and its final ruin probability when intensities of couple Cox processes have the linear relation.%随着保险业务的扩大与发展,保险公司必须购买某些险种的再保险来规避风险.为了研究保险公司购买再保险后的破产概率,文章讨论了一类保费收取与理赔发生都为Cox过程的超额赔款再保险风险模型,得到了一个破产概率明确的表达式及Lundberg不等式.

  8. Minimal model quantification of pulmonary gas exchange in intensive care patients

    DEFF Research Database (Denmark)

    Karbing, Dan Stieper; Kjærgaard, Søren; Andreassen, Hans Steen

    2011-01-01

    Mathematical models are required to describe pulmonary gas exchange. The challenge remains to find models which are complex enough to describe physiology and simple enough for clinical practice. This study aimed at finding the necessary 'minimal' modeling complexity to represent the gas exchange ...

  9. A three-demensional CFD model for gas-liquid bubble columns.

    NARCIS (Netherlands)

    Delnoij, E.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    1999-01-01

    This paper discusses the development of a three-dimensional Euler¿Lagrange CFD model for a gas¿liquid bubble column. The model resolves the time-dependent, three-dimensional motion of small, spherical gas bubbles in a liquid. Our model incorporates all relevant forces acting on a bubble rising in a

  10. Modelling and Numerical Simulation of Gas Migration in a Nuclear Waste Repository

    CERN Document Server

    Bourgeat, Alain; Smai, Farid

    2010-01-01

    We present a compositional compressible two-phase, liquid and gas, flow model for numerical simulations of hydrogen migration in deep geological radioactive waste repository. This model includes capillary effects and the gas diffusivity. The choice of the main variables in this model, Total or Dissolved Hydrogen Mass Concentration and Liquid Pressure, leads to a unique and consistent formulation of the gas phase appearance and disappearance. After introducing this model, we show computational evidences of its adequacy to simulate gas phase appearance and disappearance in different situations typical of underground radioactive waste repository.

  11. Formation mechanism of gas bubble superlattice in UMo metal fuels: Phase-field modeling investigation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Shenyang [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Burkes, Douglas E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Senor, David J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Setyawan, Wahyu [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Xu, Zhijie [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-07-08

    Nano-gas bubble superlattices are often observed in irradiated UMo nuclear fuels. However, the for- mation mechanism of gas bubble superlattices is not well understood. A number of physical processes may affect the gas bubble nucleation and growth; hence, the morphology of gas bubble microstructures including size and spatial distributions. In this work, a phase-field model integrating a first-passage Monte Carlo method to investigate the formation mechanism of gas bubble superlattices was devel- oped. Six physical processes are taken into account in the model: 1) heterogeneous generation of gas atoms, vacancies, and interstitials informed from atomistic simulations; 2) one-dimensional (1-D) migration of interstitials; 3) irradiation-induced dissolution of gas atoms; 4) recombination between vacancies and interstitials; 5) elastic interaction; and 6) heterogeneous nucleation of gas bubbles. We found that the elastic interaction doesn’t cause the gas bubble alignment, and fast 1-D migration of interstitials along $\\langle$110$\\rangle$ directions in the body-centered cubic U matrix causes the gas bubble alignment along $\\langle$110$\\rangle$ directions. It implies that 1-D interstitial migration along [110] direction should be the primary mechanism of a fcc gas bubble superlattice which is observed in bcc UMo alloys. Simulations also show that fission rates, saturated gas concentration, and elastic interaction all affect the morphology of gas bubble microstructures.

  12. Formation mechanism of gas bubble superlattice in UMo metal fuels: Phase-field modeling investigation

    Science.gov (United States)

    Hu, Shenyang; Burkes, Douglas E.; Lavender, Curt A.; Senor, David J.; Setyawan, Wahyu; Xu, Zhijie

    2016-10-01

    Nano-gas bubble superlattices are often observed in irradiated UMo nuclear fuels. However, the formation mechanism of gas bubble superlattices is not well understood. A number of physical processes may affect the gas bubble nucleation and growth; hence, the morphology of gas bubble microstructures including size and spatial distributions. In this work, a phase-field model integrating a first-passage Monte Carlo method to investigate the formation mechanism of gas bubble superlattices was developed. Six physical processes are taken into account in the model: 1) heterogeneous generation of gas atoms, vacancies, and interstitials informed from atomistic simulations; 2) one-dimensional (1-D) migration of interstitials; 3) irradiation-induced dissolution of gas atoms; 4) recombination between vacancies and interstitials; 5) elastic interaction; and 6) heterogeneous nucleation of gas bubbles. We found that the elastic interaction doesn't cause the gas bubble alignment, and fast 1-D migration of interstitials along directions in the body-centered cubic U matrix causes the gas bubble alignment along directions. It implies that 1-D interstitial migration along [110] direction should be the primary mechanism of a fcc gas bubble superlattice which is observed in bcc UMo alloys. Simulations also show that fission rates, saturated gas concentration, and elastic interaction all affect the morphology of gas bubble microstructures.

  13. Thermodynamic Model for Updraft Gasifier with External Recirculation of Pyrolysis Gas

    Directory of Open Access Journals (Sweden)

    Fajri Vidian

    2016-01-01

    Full Text Available Most of the thermodynamic modeling of gasification for updraft gasifier uses one process of decomposition (decomposition of fuel. In the present study, a thermodynamic model which uses two processes of decomposition (decomposition of fuel and char is used. The model is implemented in modification of updraft gasifier with external recirculation of pyrolysis gas to the combustion zone and the gas flowing out from the side stream (reduction zone in the updraft gasifier. The goal of the model obtains the influences of amount of recirculation pyrolysis gas fraction to combustion zone on combustible gas and tar. The significant results of modification updraft are that the increases amount of recirculation of pyrolysis gas will increase the composition of H2 and reduce the composition of tar; then the composition of CO and CH4 is dependent on equivalence ratio. The results of the model for combustible gas composition are compared with previous study.

  14. Development of a natural gas systems analysis model (GSAM)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-10-01

    This report provides an overview of the activities to date and schedule for future testing, validation, and authorized enhancements of Natural Gas Systems Analysis Model (GSAM). The goal of this report is to inform DOE managers of progress in model development and to provide a benchmark for ongoing and future research. Section II of the report provides a detailed discussion on the major GSAM development programs performed and completed during the period of performance, July 1, 1998 to September 30, 1999. Key improvements in the new GSAM version are summarized in Section III. Programmer's guides for GSAM main modules were produced to provide detailed descriptions of all major subroutines and main variables of the computer code. General logical flowcharts of the subroutines are also presented in the guides to provide overall picture of interactions between the subroutines. A standard structure of routine explanation is applied in every programmer's guide. The explanation is started with a brief description or main purpose of the routine, lists of input and output files read and created, and lists of invoked/child and calling/parent routines. In some of the guides, interactions between the routine itself and its parent and child routines are presented in the form of graphical flowchart. The explanation is then proceeded with step by step description of computer code in the subroutine where each step delegates a section of related code. Between steps, if a certain section of code needs further explanation, a Note is inserted with relevant explanation.

  15. Overview: Understanding nucleation phenomena from simulations of lattice gas models

    Science.gov (United States)

    Binder, Kurt; Virnau, Peter

    2016-12-01

    Monte Carlo simulations of homogeneous and heterogeneous nucleation in Ising/lattice gas models are reviewed with an emphasis on the general insight gained on the mechanisms by which metastable states decay. Attention is paid to the proper distinction of particles that belong to a cluster (droplet), that may trigger a nucleation event, from particles in its environment, a problem crucial near the critical point. Well below the critical point, the lattice structure causes an anisotropy of the interface tension, and hence nonspherical droplet shapes result, making the treatment nontrivial even within the conventional classical theory of homogeneous nucleation. For temperatures below the roughening transition temperature facetted crystals rather than spherical droplets result. The possibility to find nucleation barriers from a thermodynamic analysis avoiding a cluster identification on the particle level is discussed, as well as the question of curvature corrections to the interfacial tension. For the interpretation of heterogeneous nucleation at planar walls, knowledge of contact angles and line tensions is desirable, and methods to extract these quantities from simulations will be mentioned. Finally, also the problem of nucleation near the stability limit of metastable states and the significance of the spinodal curve will be discussed, in the light of simulations of Ising models with medium range interactions.

  16. Poissonian reducibility and thermal scaling within the lattice gas model and molecular dynamics model

    OpenAIRE

    Ma, Y.G.

    2000-01-01

    The emission of clusters in the nuclear disassembly is investigated within the framework of isospin dependent lattice gas model and classical molecular dynamics model. As observed in the recent experimental data, it is found that the emission of individual cluster is poissonian and thermal scaling is observed in the linear Arrhenius plots made from the average multiplicity of each cluster. The mass, isotope and charge dependent "emission barriers" are extracted from the slopes of the Arrheniu...

  17. The otherness of sexuality: excess.

    Science.gov (United States)

    Stein, Ruth

    2008-03-01

    The present essay, the second of a series of three, aims at developing an experience-near account of sexuality by rehabilitating the idea of excess and its place in sexual experience. It is suggested that various types of excess, such as excess of excitation (Freud), the excess of the other (Laplanche), excess beyond symbolization and the excess of the forbidden object of desire (Leviticus; Lacan) work synergistically to constitute the compelling power of sexuality. In addition to these notions, further notions of excess touch on its transformative potential. Such notions address excess that shatters psychic structures and that is actively sought so as to enable new ones to evolve (Bersani). Work is quoted that regards excess as a way of dealing with our lonely, discontinuous being by using the "excessive" cosmic energy circulating through us to achieve continuity against death (Bataille). Two contemporary analytic thinkers are engaged who deal with the object-relational and intersubjective vicissitudes of excess.

  18. Numerical modeling of gas mixing and bio-chemical transformations during underground hydrogen storage within the project H2STORE

    Science.gov (United States)

    Hagemann, B.; Feldmann, F.; Panfilov, M.; Ganzer, L.

    2015-12-01

    The change from fossil to renewable energy sources is demanding an increasing amount of storage capacities for electrical energy. A promising technological solution is the storage of hydrogen in the subsurface. Hydrogen can be produced by electrolysis using excessive electrical energy and subsequently converted back into electricity by fuel cells or engine generators. The development of this technology starts with adding small amounts of hydrogen to the high pressure natural gas grid and continues with the creation of pure underground hydrogen storages. The feasibility of hydrogen storage in depleted gas reservoirs is investigated in the lighthouse project H2STORE financed by the German Ministry for Education and Research. The joint research project has project members from the University of Jena, the Clausthal University of Technology, the GFZ Potsdam and the French National Center for Scientic Research in Nancy. The six sub projects are based on laboratory experiments, numerical simulations and analytical work which cover the investigation of mineralogical, geochemical, physio-chemical, sedimentological, microbiological and gas mixing processes in reservoir and cap rocks. The focus in this presentation is on the numerical modeling of underground hydrogen storage. A mathematical model was developed which describes the involved coupled hydrodynamic and microbiological effects. Thereby, the bio-chemical reaction rates depend on the kinetics of microbial growth which is induced by the injection of hydrogen. The model has been numerically implemented on the basis of the open source code DuMuX. A field case study based on a real German gas reservoir was performed to investigate the mixing of hydrogen with residual gases and to discover the consequences of bio-chemical reactions.

  19. Fundamentals of natural gas processing - hydrocarbon dew point meter modelling

    OpenAIRE

    Michalsen, Kathrine; Nævdal, Helene Sire

    2014-01-01

    When natural gas is taken from the reservoir it needs to be refined by removing liquid and other impurities in order to prevent hydrate formation in the pipelines and to keep the gas within sales specifications. Scrubbers, vertical separators, are used to remove the liquid and the efficiency of the scrubber has a great impact on the quality of the gas. To control the gas specifications and the efficiency of the scrubber, a dew point meter can be used. This tool will ideally provide the real d...

  20. Carbon dioxide corrosion: Modelling and experimental work applied to natural gas pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Loldrup Fosboel. P.

    2007-10-15

    CO{sub 2} corrosion is a general problem in the industry and it is expensive. The focus of this study is an oil gas production related problem. CO{sub 2} corrosion is observed in offshore natural gas transportation pipelines. A general overview of the problem is presented in chapter 1. The chemical system consists mainly of CO{sub 2}-Na{sub 2}CO{sub 3}-NaHCO{sub 3}-MEG-H{sub 2}O. Sodium is injected in the pipelines as NaOH in order to pH-stabilize the pipeline to avoid corrosion and MEG is injected in order to prevent gas hydrates. There are a great number of models available in the literature which may predict CO{sub 2} corrosion. These models are not very accurate and assume ideality in the main part of the equation. This thesis deals with aspect of improving the models to account for the non-ideality. A general overview and extension of the theory behind electrochemical corrosion is presented in chapter 2 to 4. The theory deals with the basic thermodynamics of electrolytes in chapter 2, the extension and general description of electrolyte mass transport in chapter 3, and the electrochemical kinetics of corrosion in chapter 4. A literature overview of CO{sub 2} corrosion is shown in chapter 5 and possible extensions of the models are discussed. A list of literature cites is given in chapter 6. The literature review in chapter 5 shows how FeCO{sub 3} plays a main part in the protection of steel. Especially the solubility of FeCO{sub 3} is an important factor. Chapter 7 discusses and validates the thermodynamic properties of FeCO{sub 3}. The study shows that there is a discrepancy in the properties of FeCO{sub 3}. Sets of consistent thermodynamic properties of FeCO{sub 3} are given. A mixed solvent electrolyte model is regressed in chapter 8 for the CO{sub 2}-Na{sub 2}CO{sub 3}-NaHCO{sub 3}-MEG-H{sub 2}O system. Parameters of the extended UNIQUAC model is fitted to literature data of VLE, SLE, heat excess and validated against heat capacity data. The model is also

  1. Spin dynamics of electron with high excess energy in GaAs investigated by the simplified circularly dichromatic pump-probe model

    Science.gov (United States)

    Teng, L. H.; Mu, L. J.; Wang, X.

    2014-03-01

    Time-resolved circularly polarized pump-probe spectroscopy is used to study the spin dynamics of electron with high excess energy in bulk GaAs at room temperature, an abnormal phenomenon that the curve taken from co-helicity circularly polarized pump-probe beam drops below the curve taken from cross-helicity circularly polarized pump-probe beam is observed. With both the spin-dependent band-filling and band-gap renormalization effects being taken into account, a simplified circularly dichromatic pump-probe model is further developed, the model can be used to fit the scanning experimental traces to retrieve the spin relaxation time, carrier recombination time, intensity coefficient of spin-dependent band-filling and band-gap renormalization effects, etc. With the parameters retrieved from the experimental data, the physical origin of the spectrum reversal can be explained in detail, both of the spin-dependent band-filling and band-gap renormalization effects contribute to the reversal spectrum.

  2. The 750 GeV diphoton excess and its explanation in 2-Higgs Doublet Models with a real inert scalar multiplet

    CERN Document Server

    Moretti, Stefano

    2015-01-01

    We discuss a possible explanation of the recently observed diphoton excess at around 750 GeV as seen by the ATLAS and CMS experiments at the Large Hadron Collider. We calculate the cross section of the diphoton signature in 2-Higgs Doublet Models with the addition of a real isospin scalar multiplet without a vacuum expectation value, where a neutral component of such a representation can be a dark matter candidate. We find that the branching fraction of an additional CP-even Higgs boson $H$ from the doublet fields into the diphoton mode can be significantly enhanced, by up to a factor of $10^3$, with respect to the case of the Standard Model. Such a sizable enhancement is realized due to multi-charged inert particle loops entering the $H\\to \\gamma\\gamma$ decay mode. Through this enhancement, we obtain a suitable cross section of the $gg\\to H \\to \\gamma\\gamma$ process to explain the data, i.e., ${\\cal O}(10)$ fb level, with the fixed mass of $H$ being 750 GeV.

  3. Can Zee-Babu model implemented with scalar dark matter explain both Fermi/LAT 130 GeV $\\gamma$-ray excess and neutrino physics ?

    CERN Document Server

    Baek, Seungwon; Senaha, Eibun

    2012-01-01

    We implement the Zee-Babu model for the neutrino masses and mixings by incorporating a scalar dark matter $X$. The singly and doubly charged scalars that are new in the Zee-Babu model can explain the large annihilation cross section of a dark matter pair into two photons as hinted by the recent analysis of the Fermi $\\gamma$-ray space telescope data, if new charged scalars are relatively light and have large couplings to a pair of dark matter particles. These new scalars can also enhance the $B (H \\rightarrow \\gamma\\gamma)$, as the recent LHC results may suggest. The dark matter relic density can be explained. The direct detection rate of the dark matter is predicted to be about one order of magnitude down from the current experimental bound. However, it turns out that neutrino masses are too small within the parameter space fitting the 130 GeV $\\gamma$-ray excess. There should be additional contributions to the neutrino masses and mixings without new extra charged particles, and the Type-I seesaw can do this...

  4. Modeling syngas-fired gas turbine engines with two dilutants

    Science.gov (United States)

    Hawk, Mitchell E.

    2011-12-01

    Prior gas turbine engine modeling work at the University of Wyoming studied cycle performance and turbine design with air and CO2-diluted GTE cycles fired with methane and syngas fuels. Two of the cycles examined were unconventional and innovative. The work presented herein reexamines prior results and expands the modeling by including the impacts of turbine cooling and CO2 sequestration on GTE cycle performance. The simple, conventional regeneration and two alternative regeneration cycle configurations were examined. In contrast to air dilution, CO2 -diluted cycle efficiencies increased by approximately 1.0 percentage point for the three regeneration configurations examined, while the efficiency of the CO2-diluted simple cycle decreased by approximately 5.0 percentage points. For CO2-diluted cycles with a closed-exhaust recycling path, an optimum CO2-recycle pressure was determined for each configuration that was significantly lower than atmospheric pressure. Un-cooled alternative regeneration configurations with CO2 recycling achieved efficiencies near 50%, which was approximately 3.0 percentage points higher than the conventional regeneration cycle and simple cycle configurations that utilized CO2 recycling. Accounting for cooling of the first two turbine stages resulted in a 2--3 percentage point reduction in un-cooled efficiency, with air dilution corresponding to the upper extreme. Additionally, when the work required to sequester CO2 was accounted for, cooled cycle efficiency decreased by 4--6 percentage points, and was more negatively impacted when syngas fuels were used. Finally, turbine design models showed that turbine blades are shorter with CO2 dilution, resulting in fewer design restrictions.

  5. Minimal model quantification of pulmonary gas exchange in intensive care patients

    DEFF Research Database (Denmark)

    Karbing, Dan Stieper; Kjærgaard, Søren; Andreassen, Steen

    2011-01-01

    of both oxygen and carbon dioxide. Three models of varying complexity were compared for their ability to fit measured data from intensive care patients and to provide adequate description of patients' gas exchange abnormalities. Pairwise F-tests showed that a two parameter model provided superior fit......Mathematical models are required to describe pulmonary gas exchange. The challenge remains to find models which are complex enough to describe physiology and simple enough for clinical practice. This study aimed at finding the necessary 'minimal' modeling complexity to represent the gas exchange...... to patient data compared to a shunt only model (p...

  6. MATHEMATICAL MODELING OF THERMOPHYSICAL PARAMETERS OF VORTEX HEAT EXCHANGER OF HEATING SYSTEMS OF GAS DISTRIBUTION POINTS PREMISES

    Directory of Open Access Journals (Sweden)

    V. A. Lapin

    2009-09-01

    Full Text Available The mathematical model of heat transfer in vortex heat exchanger using natural gas energy which is released under decompression in gas-main pipe-lines for consumers of gas supply systems (dwellings, public and industrial buildings.

  7. Experimental and Modeling Studies on the Prediction of Gas Hydrate Formation

    Directory of Open Access Journals (Sweden)

    Jian-Yi Liu

    2015-01-01

    Full Text Available On the base of some kinetics model analysis and kinetic observation of hydrate formation process, a new prediction model of gas hydrate formation is proposed. The analysis of the present model shows that the formation of gas hydrate not only relevant with gas composition and free water content but also relevant with temperature and pressure. Through contrast experiment, the predicted result of the new prediction method of gas hydrate crystallization kinetics is close to measured result, it means that the prediction method can reflect the hydrate crystallization accurately.

  8. Geomechanical modelling of the induced seismicity for a gas field

    NARCIS (Netherlands)

    Orlic, B.; Eijs, R. van; Scheffers, B.

    2001-01-01

    Gas production from a reservoir may lead to reactivation of nearby faults, which is likely to cause local seismic events. This paper is focusing on the calculations of stress evolution during depletion of a gas reservoir in order to investigate the possibilities for the reactivation and slip on norm

  9. Modeling studies of biological gas desulfurization under haloalkaline conditions

    NARCIS (Netherlands)

    Klok, J.B.M.

    2015-01-01

    Abstract Biogas, synthesis and natural gas streams often require treatment because of the presence of gaseous hydrogen sulphide (H2S). About 25 years ago, a biotechnological gas treatment process was developed as an alternative to the conventionally applied technologies. This proces

  10. Modeling studies of biological gas desulfurization under haloalkaline conditions

    NARCIS (Netherlands)

    Klok, J.B.M.

    2015-01-01

    Abstract Biogas, synthesis and natural gas streams often require treatment because of the presence of gaseous hydrogen sulphide (H2S). About 25 years ago, a biotechnological gas treatment process was developed as an alternative to the conventionally applied technologies. This proces

  11. Simulation and Modeling of Flow in a Gas Compressor

    Directory of Open Access Journals (Sweden)

    Anna Avramenko

    2015-01-01

    Full Text Available The presented research demonstrates the results of a series of numerical simulations of gas flow through a single-stage centrifugal compressor with a vaneless diffuser. Numerical results were validated with experiments consisting of eight regimes with different mass flow rates. The steady-state and unsteady simulations were done in ANSYS FLUENT 13.0 and NUMECA FINE/TURBO 8.9.1 for one-period geometry due to periodicity of the problem. First-order discretization is insufficient due to strong dissipation effects. Results obtained with second-order discretization agree with the experiments for the steady-state case in the region of high mass flow rates. In the area of low mass flow rates, nonstationary effects significantly influence the flow leading stationary model to poor prediction. Therefore, the unsteady simulations were performed in the region of low mass flow rates. Results of calculation were compared with experimental data. The numerical simulation method in this paper can be used to predict compressor performance.

  12. Modeling corrosion behavior of gas tungsten arc welded titanium alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The pitting corrosion characteristics of pulse TIG welded Ti-6Al-4V titanium alloy in marine environment were explained.Besides the rapid advance of titanium metallurgy, this is also due to the successful solution of problems associated with the development of titanium alloy welding. The preferred welding process of titanium alloy is frequently gas tungsten arc(GTA) welding due to its comparatively easier applicability and better economy. In the case of single pass GTA welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. The benefit of the process is utilized to obtain better quality titanium weldments. Four factors, five levels, central composite, rotatable design matrix are used to optimize the required number of experiments. The mathematical models have been developed by response surface method(RSM). The results reveal that the titanium alloy can form a protective scale in marine environment and is resistant to pitting corrosion. Experimental results are provided to illustrate the proposed approach.

  13. Calculating soil gas fluxes from gas concentration profiles: can we use standard DS models or should we use site-specific DS models?

    Science.gov (United States)

    Paulus, Sinikka; Jochheim, Hubert; Wirth, Stephan; Maier, Martin

    2015-04-01

    The apparent gas diffusion coefficient in soil (DS) is an important parameter describing soil aeration. It also links the profiles of soil gas concentration and soil gas flux using Fick's law. Soil gas diffusivity depends mainly on the structure of the pore system and the soil moisture status. There are several standard DS-models available that can easily be used for calculating DS. Another, more laborious option is to calibrate site specific DS models on soil core samples from the respective profile. We tested 4 standard DS models and a site-specific model and compared the resulting soil gas fluxes in two forest soils. Differences between the models were substantial. Another very important effect, however, is that standard DS models are usually derived from a single soil moisture measurement (device), that can result in an substantial offset in soil moisture estimation. The mean soil moisture content at a depth can be addressed more accurately by taking several soil cores. As a consequence, using standard DS models in combination with a single soil moisture measurement is less reliable than using site-specific models based on several soil samples.

  14. Escalation scenarios initiated by gas explosions on offshore installations. Probabilistic cause and consequence modelling

    Energy Technology Data Exchange (ETDEWEB)

    Eknes, Monika Loeland

    1996-12-31

    This Dr. ing. thesis deals with escalation scenarios initiated by gas explosions on offshore installations. Gas explosions is one of the major hazards to such installations. The objectives were to estimate the probability of ignition and frequency of gas explosions for gas leaks on top sides of offshore installations, and to estimate the response and resistance of components that could result in escalation if they failed. Main fields considered cover risk analysis methodology, gas explosions, simplified escalation models, evaluation of structural consequences, case studies, and guidelines. 107 refs., 33 figs., 33 tabs.

  15. Aerophagia : Excessive Air Swallowing Demonstrated by Esophageal Impedance Monitoring

    NARCIS (Netherlands)

    Hemmink, Gerrit J. M.; Weusten, Bas L. A. M.; Bredenoord, Albert J.; Timmer, Robin; Smout, Andre J. P. M.

    2009-01-01

    BACKGROUND & AIMS: Patients with aerophagia suffer from the presence of an excessive volume of intestinal gas, which is thought to result from excessive air ingestion. However, this has not been shown thus far. The aim of this study was therefore to assess swallowing and air swallowing frequencies i

  16. Literature search for offsite data to improve the DWPF melter off-gas model

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, W.E.

    2000-05-04

    This report documents the literature search performed and any relevant data that may help relax some of the constraints on the DWPF melter off-gas model. The objective of this task was to look for outside sources of technical data to help reduce some of the conservatism built in the DWPF melter off-gas model.

  17. Limits from Weak Gravity Conjecture on Chaplygin-Gas-Type Models

    Institute of Scientific and Technical Information of China (English)

    WU Xing; ZHU Zong-Hong

    2008-01-01

    @@ The weak gravity conjecture is proposed as a criterion to distinguish the landscape from the swampland in string theory. As an application in cosmology of this conjecture, we use it to impose theoretical constraint on parameters of the Chaplygin-gas-type models. Our analysis indicates that the Chaplygin-gas-type models realized in quintessence field are in the swampland.

  18. Cognitive-motivational model of obesity. Motivational mechanisms and cognitive biases underlying the processing of food-related images by people with excess body weight.

    Science.gov (United States)

    Pawłowska, Monika; Kalka, Dorota

    2015-01-01

    Obesity is a constantly escalating problem in all age groups. In the face of ubiquitous images of food, colourful advertisements of high-calorie meals and beverages, it is necessary to examine the role of the memory and attention mechanism in the processing of these stimuli. Knowledge regarding this subject will surely significantly contribute to the improvement of prevention and management of obesity programs designed to prevent secondary psychological difficulties, including depression. This paper presents cognitive-motivational model of obesity, according to which the description of mechanisms of eating disorders occurrence should include not only motivational factors but also the cognitive ones. The paper shows theoretical perspectives on the problem of obesity irrespective of its origin, as well as the latest empirical reports in this field. The presented survey demonstrates the lack of explicit research findings related to the processing of high and low-calorie food images by persons with excess weight. It seems that the knowledge of the basic mechanisms involved in the processing of these stimuli and the exploration of this phenomenon will allow to improve programs whose objective is to prevent obesity.

  19. Cognitive-motivational model of obesity. Motivational mechanisms and cognitive biases underlying the processing of food-related images by people with excess body weight.

    Directory of Open Access Journals (Sweden)

    Monika Pawłowska

    2015-10-01

    Full Text Available Obesity is a constantly escalating problem in all age groups. In the face of ubiquitous images of food, colourful advertisements of high-calorie meals and beverages, it is necessary to examine the role of the memory and attention mechanism in the processing of these stimuli. Knowledge regarding this subject will surely significantly contribute to the improvement of prevention and management of obesity programs designed to prevent secondary psychological difficulties, including depression. This paper presents cognitive-motivational model of obesity, according to which the description of mechanisms of eating disorders occurrence should include not only motivational factors but also the cognitive ones. The paper shows theoretical perspectives on the problem of obesity irrespective of its origin, as well as the latest empirical reports in this field. The presented survey demonstrates the lack of explicit research findings related to the processing of high and low-calorie food images by persons with excess weight. It seems that the knowledge of the basic mechanisms involved in the processing of these stimuli and the exploration of this phenomenon will allow to improve programs whose objective is to prevent obesity.

  20. Gas-dynamic modeling of gas flow in semi-closed space including channel surface fluctuation

    Science.gov (United States)

    Petrova, E. N.; Salnikov, A. F.

    2016-10-01

    In this article frequency interaction conditions, that affect on acoustic stability of solid-propellant rocket engine (SPRE) action, and its influence on level change of pressure fluctuations with longitudinal gas oscillations in the combustion chamber (CC) are considered. Studies of CC in the assessment of the operating rocket engine stability are reported.

  1. Excess flow shutoff valve

    Energy Technology Data Exchange (ETDEWEB)

    Kiffer, Micah S.; Tentarelli, Stephen Clyde

    2016-02-09

    Excess flow shutoff valve comprising a valve body, a valve plug, a partition, and an activation component where the valve plug, the partition, and activation component are disposed within the valve body. A suitable flow restriction is provided to create a pressure difference between the upstream end of the valve plug and the downstream end of the valve plug when fluid flows through the valve body. The pressure difference exceeds a target pressure difference needed to activate the activation component when fluid flow through the valve body is higher than a desired rate, and thereby closes the valve.

  2. Modeling of Hybrid Permanent Magnetic-Gas Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2009-01-01

    Modern turbomachinery applications require nowadays ever-growing rotational speeds and high degree of reliability. It then becomes natural to focus the attention of the research to contact-free bearings elements. The present alternatives focus on gas lubricated journal bearings or magnetic bearings....... In the present paper both the technologies are combined with the aim of developing a new kind of hybrid permanent magnetic - gas bearing. This new kind of machine is intended to exploit the benefits of the two technologies while minimizing their drawbacks. The poor start-up and low speed operation performance...... of the gas bearing is balanced by the properties of the passive magnetic one. At high speeds the dynamic characteristics of the gas bearing are improved by offsetting the stator ring of the permanent magnetic bearing. Furthermore this design shows a kind of redundancy, which offers soft failure properties...

  3. `Gas cushion' model and hydrodynamic boundary conditions for superhydrophobic textures

    CERN Document Server

    Nizkaya, Tatiana V; Vinogradova, Olga I

    2014-01-01

    Superhydrophobic Cassie textures with trapped gas bubbles reduce drag, by generating large effective slip, which is important for a variety of applications that involve a manipulation of liquids at the small scale. Here we discuss how the dissipation in the gas phase of textures modifies their friction properties and effective slip. We propose an operator method, which allows us the mapping of the flow in the gas subphase to a local slip boundary condition at the liquid/gas interface. The determined uniquely local slip length depends on the viscosity contrast and underlying topography, and can be immediately used to evaluate an effective slip of the texture. Beside Cassie surfaces our approach is valid for Wenzel textures, where a liquid follows the surface relief, as well as for rough surfaces impregnated by a low-viscosity `lubricant'. These results provide a framework for the rational design of textured surfaces for numerous applications.

  4. Multicomponent seismic forward modeling of gas hydrates beneath the seafloor

    Institute of Scientific and Technical Information of China (English)

    Yang Jia-Jia; He Bing-Shou; Zhang Jian-Zhong

    2014-01-01

    We investigated the effect of microscopic distribution modes of hydrates in porous sediments, and the saturation of hydrates and free gas on the elastic properties of saturated sediments. We simulated the propagation of seismic waves in gas hydrate-bearing sediments beneath the seafloor, and obtained the common receiver gathers of compressional waves (P-waves) and shear waves (S-waves). The numerical results suggest that the interface between sediments containing gas hydrates and free gas produces a large-amplitude bottom-simulating reflector. The analysis of multicomponent common receiver data suggests that ocean-bottom seismometers receive the converted waves of upgoing P-and S-waves, which increases the complexity of the wavefield record.

  5. Historical greenhouse gas concentrations for climate modelling (CMIP6)

    Science.gov (United States)

    Meinshausen, Malte; Vogel, Elisabeth; Nauels, Alexander; Lorbacher, Katja; Meinshausen, Nicolai; Etheridge, David M.; Fraser, Paul J.; Montzka, Stephen A.; Rayner, Peter J.; Trudinger, Cathy M.; Krummel, Paul B.; Beyerle, Urs; Canadell, Josep G.; Daniel, John S.; Enting, Ian G.; Law, Rachel M.; Lunder, Chris R.; O'Doherty, Simon; Prinn, Ron G.; Reimann, Stefan; Rubino, Mauro; Velders, Guus J. M.; Vollmer, Martin K.; Wang, Ray H. J.; Weiss, Ray

    2017-05-01

    Atmospheric greenhouse gas (GHG) concentrations are at unprecedented, record-high levels compared to the last 800 000 years. Those elevated GHG concentrations warm the planet and - partially offset by net cooling effects by aerosols - are largely responsible for the observed warming over the past 150 years. An accurate representation of GHG concentrations is hence important to understand and model recent climate change. So far, community efforts to create composite datasets of GHG concentrations with seasonal and latitudinal information have focused on marine boundary layer conditions and recent trends since the 1980s. Here, we provide consolidated datasets of historical atmospheric concentrations (mole fractions) of 43 GHGs to be used in the Climate Model Intercomparison Project - Phase 6 (CMIP6) experiments. The presented datasets are based on AGAGE and NOAA networks, firn and ice core data, and archived air data, and a large set of published studies. In contrast to previous intercomparisons, the new datasets are latitudinally resolved and include seasonality. We focus on the period 1850-2014 for historical CMIP6 runs, but data are also provided for the last 2000 years. We provide consolidated datasets in various spatiotemporal resolutions for carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), as well as 40 other GHGs, namely 17 ozone-depleting substances, 11 hydrofluorocarbons (HFCs), 9 perfluorocarbons (PFCs), sulfur hexafluoride (SF6), nitrogen trifluoride (NF3) and sulfuryl fluoride (SO2F2). In addition, we provide three equivalence species that aggregate concentrations of GHGs other than CO2, CH4 and N2O, weighted by their radiative forcing efficiencies. For the year 1850, which is used for pre-industrial control runs, we estimate annual global-mean surface concentrations of CO2 at 284.3 ppm, CH4 at 808.2 ppb and N2O at 273.0 ppb. The data are available at https://esgf-node.llnl.gov/search/input4mips/ and http

  6. The Application of Bivariate Threshold Excess Model in the Atmospheric Environment%二元超阈值模型在环境中的应用

    Institute of Scientific and Technical Information of China (English)

    任国荣

    2012-01-01

    In recent years, more and more air pollutants have been discharged into the atmosphere. When pollutants in the atmosphere reach a certain amount, some kinds of air pollution events would happen. The bivariate threshold excess model and its application in atmospheric environment are mainly studied. When studying the extremes values of two variables, each variable can be modeled using univariate techniques, however, the extreme value inter-relationships would also be needed to study. A measure to study tail correlation between two variables is given. Then it was applied to the indicators of atmospheric environment in Shanghai. The result is that APIs for re-spirable particulate matter and for sulfur dioxide have a stronger tail dependence. In order to get a better understanding of two indicators, a bivariate threshold excess model is need to build. Firstly, distribution function for every index is established. Secondly, asymmetric Logistic model is selected as the structure functions for APIs of re-spirable particulate matter and sulfur dioxide. Then with this functions distribution of two indexes in case of exceeding the threshold is established, which can be used to analysis and forecast how the two indexes change in future.%近年来,随着现代工业和交通运输业的飞速发展,大气中排放物的数量越来越多,种类也越来越复杂,产生了越来越严重的大气环境污染.本文主要研究二元超阈值方法及其在大气环境中的应用.研究二元极值分布,除了要知道各个变量的边缘分布,还需要知道两个变量之间的尾部相关性.给出了两种度量随机变量尾部相关性的方法,并将其应用于上海市大气环境指标中,发现可吸入颗粒物API与二氧化硫API具有较强的尾部相关性.为了更深入地了解两个指标间的尾部相关性及其两个指标的走势,建立了二元超阈值模型.首先,根据阈值模型建立了每个指标的分布

  7. Model analysis of energy consumption and greenhouse gas emissions of sewage sludge treatment systems with different processes and scales.

    Science.gov (United States)

    Soda, S; Iwai, Y; Sei, K; Shimod, Y; Ike, M

    2010-01-01

    An energy consumption model was developed for evaluating sewage sludge treatment plants (SSTPs) incorporating various treatment processes such as thickening, anaerobic digestion, dewatering, incineration, and melting. Based on data analyses from SSTPs in Osaka, Japan, electricity consumption intensities for thickening, anaerobic digestion, dewatering, incineration, and melting and heat consumption intensities for anaerobic digestion, incineration, and melting were expressed as functions of sludge-loading on each unit process. The model was applied for predicting the energy consumption and greenhouse gas (GHG) emissions of SSTPs using various treatment processes and power and heat generation processes using digestion gas. Results showed that SSTPs lacking incineration and melting processes but having power generation processes showed excess energy production at the high sludge-loading rate. Energy consumption of the SSTPs without incineration and melting processes were low, but their GHG emissions were high because of CH(4) and N(2)O emissions from sludge cake at the landfill site. Incineration and melting processes consume much energy, but have lower CH(4) and N(2)O emissions.

  8. An electricity price model with consideration to load and gas price effects

    Institute of Scientific and Technical Information of China (English)

    黄民翔; 陶小虎; 韩祯祥

    2003-01-01

    Some characteristics of the electricity load and prices are studied, and the relationship between electricity prices and gas (fnel) prices is analyzed in this paper. Because electricity prices are strongly depen-dent on load and gas prices, the authors constructed a model for electricity prices based on the effects of these two factors; and used the Geometric Mean Reversion Brownian Motion (GMRBM) model to describe the electricity load process, and a Geometric Brownian Motion(GBM) model to describe the gas prices ; deduced the price stochastic process model based on the above load model and gas price model. This paper also presents methods for parameters estimation, and proposes some methods to solve the model.

  9. EIA model documentation: Documentation of the Oil and Gas Supply Module (OGSM)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    The purpose of this report is to define the objectives of the Oil and Gas Supply Model (OGSM), to describe the model`s basic approach, and to provide detail on how the model works. This report is intended as a reference document for model analysts, users, and the public. Projected production estimates of US crude oil and natural gas are based on supply functions generated endogenously within National Energy Modeling System (NEMS) by the OGSM. OGSM encompasses domestic crude oil and natural gas supply by both conventional and nonconventional recovery techniques. Nonconventional recovery includes enhanced oil recovery (EOR), and unconventional gas recovery (UGR) from tight gas formations, Devonian shale and coalbeds. Crude oil and natural gas projects are further disaggregated by geographic region. OGSM projects US domestic oil and gas supply for six Lower 48 onshore regions, three offshore regions, and Alaska. The general methodology relies on forecasted drilling expenditures and average drilling costs to determine exploratory and developmental drilling levels for each region and fuel type. These projected drilling levels translate into reserve additions, as well as a modification of the production capacity for each region. OGSM also represents foreign trade in natural gas, imports and exports by entry region.

  10. Fast and accurate calculation of dilute quantum gas using Uehling-Uhlenbeck model equation

    Science.gov (United States)

    Yano, Ryosuke

    2017-02-01

    The Uehling-Uhlenbeck (U-U) model equation is studied for the fast and accurate calculation of a dilute quantum gas. In particular, the direct simulation Monte Carlo (DSMC) method is used to solve the U-U model equation. DSMC analysis based on the U-U model equation is expected to enable the thermalization to be accurately obtained using a small number of sample particles and the dilute quantum gas dynamics to be calculated in a practical time. Finally, the applicability of DSMC analysis based on the U-U model equation to the fast and accurate calculation of a dilute quantum gas is confirmed by calculating the viscosity coefficient of a Bose gas on the basis of the Green-Kubo expression and the shock layer of a dilute Bose gas around a cylinder.

  11. Algebraic model for bubble tracking in horizontal gas-liquid flow

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Felipe G.C. de; Tisserant, Hendy R. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Morales, Rigoberto E.M. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica e de Materiais; Mazza, Ricardo A.; Rosa, Eugenio S. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica

    2008-07-01

    The current work extends the concept of unit-cell applied in gas-liquid slug flow models to predict the evolution of the gas and liquid flow properties along a horizontal pipe. The motivation of this model is its simplicity, easiness of application and low computational cost. It is a useful tool of reference data generation in order to check the consistency of numerical slug tracking models. The potential of the model is accessed by comparing the gas bubbles and liquid slug sizes, the translational bubble velocity and the pressure drop against experimental data. (author)

  12. Development of a Random Field Model for Gas Plume Detection in Multiple LWIR Images.

    Energy Technology Data Exchange (ETDEWEB)

    Heasler, Patrick G.

    2008-09-30

    This report develops a random field model that describes gas plumes in LWIR remote sensing images. The random field model serves as a prior distribution that can be combined with LWIR data to produce a posterior that determines the probability that a gas plume exists in the scene and also maps the most probable location of any plume. The random field model is intended to work with a single pixel regression estimator--a regression model that estimates gas concentration on an individual pixel basis.

  13. Modelling and analysis of offshore energy systems on North Sea oil and gas platforms

    DEFF Research Database (Denmark)

    Nguyen, Tuong-Van; Elmegaard, Brian; Pierobon, Leonardo

    2012-01-01

    export, and power generation. In this paper, a generic model of a North Sea oil and gas platform is described and the most thermodynamically inefficient processes are identified by performing an exergy analysis. Models and simulations are built and run with the tools Aspen Plus R, DNA and Aspen HYSYS R......Offshore processes are associated with significant energy consumption and large CO2 emissions. Conventional North Sea oil and gas facilities include the following operations: crude oil separation, gas compression and purification, wastewater treatment, gas lifting, seawater injection, oil and gas...... and gas processing system, consuming 4-6 MW and 3-7 MW respectively, while the power generation system alone is responsible for 54-63 MW....

  14. The Water-Induced Linear Reduction Gas Diffusivity Model Extended to Three Pore Regions

    DEFF Research Database (Denmark)

    Chamindu, T. K. K. Deepagoda; de Jonge, Lis Wollesen; Kawamoto, Ken

    2015-01-01

    . Characterization of soil functional pore structure is an essential prerequisite to understand key gas transport processes in variably saturated soils in relation to soil ecosystems, climate, and environmental services. In this study, the water-induced linear reduction (WLR) soil gas diffusivity model originally......An existing gas diffusivity model developed originally for sieved, repacked soils was extended to characterize gas diffusion in differently structured soils and functional pore networks. A gas diffusivity-derived pore connectivity index was used as a measure of soil structure development...... developed for sieved, repacked soil was extended to two simple, linear regions to characterize gas diffusion and functional pore-network structure also in intact, structured soil systems. Based on the measurements in soils with markedly different pore regions, we showed that the two linear regions can...

  15. Numerical Modeling of Enhanced Nitrogen Dissolution During Gas Tungsten Arc Welding

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, T A

    2001-08-17

    Nitrogen concentrations far in excess of Sieverts' Law calculations and as high as 0.2 wt.% have been obtained in steel welds during arc welding. Such high concentrations of nitrogen in the weld metal can originate from a variety of sources, depending on the welding operation in question. One such mechanism involves the interaction between the surrounding atmosphere, which is about 80% nitrogen, and the plasma phase above the weld pool. Impingement of the surrounding atmosphere into the arc column, which is primarily composed of an inert shielding gas, can be due, in part, to insufficient shielding of the weld metal. In other cases, nitrogen can be purposefully added to the shielding gas to enhance the microstructural evolution of the weld metal. The mechanisms responsible for enhanced nitrogen concentrations are of significant interest. In both arc melting and welding operations, a plasma phase exists above the liquid metal. This plasma phase, which is composed of a number of different species not normally observed in gas-metal systems, significantly alters the nitrogen absorption reaction in liquid iron and steel. Monatomic nitrogen (N) is considered to be the species responsible for the observed enhancements in the nitrogen concentration. This role for monatomic nitrogen is based on its significantly higher solubility in iron with partial pressures many orders of magnitude less than that for diatomic nitrogen. It has also been proposed that the total amount of nitrogen present in the liquid metal is the balance of two independent processes. Monatomic nitrogen is absorbed through the interface between the arc and the liquid metal. Once a saturation level is reached at any location on the metal surface, nitrogen is then expelled from the surface of the liquid metal. This expulsion of nitrogen from the weld pool surface occurs via a desorption reaction, in which bubbles form at the surface and other heterogeneous nucleation sites in the liquid melt. These

  16. Gas kinetic algorithm for flows in Poiseuille-like microchannels using Boltzmann model equation

    Institute of Scientific and Technical Information of China (English)

    LI; Zhihui; ZHANG; Hanxin; FU; Song

    2005-01-01

    The gas-kinetic unified algorithm using Boltzmann model equation have been extended and developed to solve the micro-scale gas flows in Poiseuille-like micro-channels from Micro-Electro-Mechanical Systems (MEMS). The numerical modeling of the gas kinetic boundary conditions suitable for micro-scale gas flows is presented. To test the present method, the classical Couette flows with various Knudsen numbers, the gas flows from short microchannels like plane Poiseuille and the pressure-driven gas flows in two-dimensional short microchannels have been simulated and compared with the approximate solutions of the Boltzmann equation, the related DSMC results, the modified N-S solutions with slip-flow boundary theory, the gas-kinetic BGK-Burnett solutions and the experimental data. The comparisons show that the present gas-kinetic numerical algorithm using the mesoscopic Boltzmann simplified velocity distribution function equation can effectively simulate and reveal the gas flows in microchannels. The numerical experience indicates that this method may be a powerful tool in the numerical simulation of micro-scale gas flows from MEMS.

  17. Amplitude versus offset modeling of the bottom simulating reflection associated with submarine gas hydrates

    Science.gov (United States)

    Andreassen, K.; Hart, P.E.; MacKay, M.

    1997-01-01

    A bottom simulating seismic reflection (BSR) that parallels the sea floor occurs worldwide on seismic profiles from outer continental margins. The BSR coincides with the base of the gas hydrate stability field and is commonly used as indicator of natural submarine gas hydrates. Despite the widespread assumption that the BSR marks the base of gas hydrate-bearing sediments, the occurrence and importance of low-velocity free gas in the sediments beneath the BSR has long been a subject of debate. This paper investigates the relative abundance of hydrate and free gas associated with the BSR by modeling the reflection coefficient or amplitude variation with offset (AVO) of the BSR at two separate sites, offshore Oregon and the Beaufort Sea. The models are based on multichannel seismic profiles, seismic velocity data from both sites and downhole log data from Oregon ODP Site 892. AVO studies of the BSR can determine whether free gas exists beneath the BSR if the saturation of gas hydrate above the BSR is less than approximately 30% of the pore volume. Gas hydrate saturation above the BSR can be roughly estimated from AVO studies, but the saturation of free gas beneath the BSR cannot be constrained from the seismic data alone. The AVO analyses at the two study locations indicate that the high amplitude BSR results primarily from free gas beneath the BSR. Hydrate concentrations above the BSR are calculated to be less than 10% of the pore volume for both locations studied.

  18. Integrated field modelling[Oil and gas fields

    Energy Technology Data Exchange (ETDEWEB)

    Nazarian, Bamshad

    2002-07-01

    This research project studies the feasibility of developing and applying an integrated field simulator to simulate the production performance of an entire oil or gas field. It integrates the performance of the reservoir, the wells, the chokes, the gathering system, the surface processing facilities and whenever applicable, gas and water injection systems. The approach adopted for developing the integrated simulator is to couple existing commercial reservoir and process simulators using available linking technologies. The simulators are dynamically linked and customised into a single hybrid application that benefits from the concept of open software architecture. The integrated field simulator is linked to an optimisation routine developed based on the genetic algorithm search strategies. This enables optimisation of the system at field level, from the reservoir to the process. Modelling the wells and the gathering network is achieved by customising the process simulator. This study demonstrated that the integrated simulation improves current capabilities to simulate the performance of the entire field and optimise its design. This is achieved by evaluating design options including spread and layout of the wells and gathering system, processing alternatives, reservoir development schemes and production strategies. Effectiveness of the integrated simulator is demonstrated and tested through several field-level case studies that discuss and investigate technical problems relevant to offshore field development. The case studies cover topics such as process optimisation, optimum tie-in of satellite wells into existing process facilities, optimal well location and field layout assessment of a high pressure high temperature deepwater oil field. Case study results confirm the viability of the total field simulator by demonstrating that the field performance simulation and optimal design were obtained in an automated process with treasonable computation time. No significant

  19. Integrated field modelling[Oil and gas fields

    Energy Technology Data Exchange (ETDEWEB)

    Nazarian, Bamshad

    2002-07-01

    This research project studies the feasibility of developing and applying an integrated field simulator to simulate the production performance of an entire oil or gas field. It integrates the performance of the reservoir, the wells, the chokes, the gathering system, the surface processing facilities and whenever applicable, gas and water injection systems. The approach adopted for developing the integrated simulator is to couple existing commercial reservoir and process simulators using available linking technologies. The simulators are dynamically linked and customised into a single hybrid application that benefits from the concept of open software architecture. The integrated field simulator is linked to an optimisation routine developed based on the genetic algorithm search strategies. This enables optimisation of the system at field level, from the reservoir to the process. Modelling the wells and the gathering network is achieved by customising the process simulator. This study demonstrated that the integrated simulation improves current capabilities to simulate the performance of the entire field and optimise its design. This is achieved by evaluating design options including spread and layout of the wells and gathering system, processing alternatives, reservoir development schemes and production strategies. Effectiveness of the integrated simulator is demonstrated and tested through several field-level case studies that discuss and investigate technical problems relevant to offshore field development. The case studies cover topics such as process optimisation, optimum tie-in of satellite wells into existing process facilities, optimal well location and field layout assessment of a high pressure high temperature deepwater oil field. Case study results confirm the viability of the total field simulator by demonstrating that the field performance simulation and optimal design were obtained in an automated process with treasonable computation time. No significant

  20. A numerical study of gas transport in human lung models

    Science.gov (United States)

    Lin, Ching-Long; Hoffman, Eric A.

    2005-04-01

    Stable Xenon (Xe) gas has been used as an imaging agent for decades in its radioactive form, is chemically inert, and has been used as a ventilation tracer in its non radioactive form during computerized tomography (CT) imaging. Magnetic resonance imaging (MRI) using hyperpolarized Helium (He) gas and Xe has also emerged as a powerful tool to study regional lung structure and function. However, the present state of knowledge regarding intra-bronchial Xe and He transport properties is incomplete. As the use of these gases rapidly advances, it has become critically important to understand the nature of their transport properties and to, in the process, better understand the role of gas density in general in determining regional distribution of respiratory gases. In this paper, we applied the custom developed characteristic-Galerkin finite element method, which solves the three-dimensional (3D) incompressible variable-density Navier-Stokes equations, to study the transport of Xe and He in the CT-based human lung geometries, especially emulating the washin and washout processes. The realistic lung geometries are segmented and reconstructed from CT images as part of an effort to build a normative atlas (NIH HL-064368) documenting airway geometry over 4 decades of age in healthy and disease-state adult humans. The simulation results show that the gas transport process depends on the gas density and the body posture. The implications of these results on the difference between washin and washout time constants are discussed.

  1. Compressible gas gills of diving insects: measurements and models.

    Science.gov (United States)

    Matthews, Philip G D; Seymour, Roger S

    2010-05-01

    Many diving insects collect a bubble of air from the surface to supply their oxygen requirements while submerged. It has been theorised that these air bubbles may also act as compressible gas gills, as the low oxygen partial pressure P(O(2))within the bubble caused by the insect's respiration creates a gradient capable of driving the diffusion of oxygen from the water into the bubble. Under these conditions nitrogen diffuses in the opposite direction, resulting in a situation where the volume of the bubble is continually shrinking while oxygen is obtained. This study measures changes in volume and P(O(2)) within the gas gills held by a tethered water bug, Agraptocorixa eurynome. Both gill volume and P(O(2)) drop rapidly at the beginning of a dive, but eventually the P(O(2)) reaches an apparently stable level while volume continually declines at a slower rate. Active ventilation of the gill is crucial to maintaining oxygen uptake. These measurements are used to calculate oxygen flux into the gas gill and the oxygen consumption rate V(O(2)) of the bug. The effectiveness of a gas gill as a respiratory organ is also demonstrated by determining the critical P(O(2)) of the water bug and comparing this with measured gas gill P(O(2)) and calculated V(O(2)) .

  2. Modeling of microbial gas generation: application to the eastern Mediterranean “Biogenic Play”

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, M.; Dubille, M.; Montadert, L.

    2016-07-01

    Biogenic gas is becoming increasingly important as an exploration target in the petroleum industry because it occurs in geologically predictable circumstances and in large quantities at shallow depths as free gas or gas hydrates. As accumulations of biogenic gas result in a subtle synchronization between early generation and early trapping, we integrated a macroscopic model of microbial gas generation within a 3D basin and petroleum system forward simulator. The macroscopic model is based on a microscopic model, which consists in a 1D sedimentary column that accounts for sedimentation, compaction, Darcy flow and Diffusion flow. The organic carbon is the only non-soluble element considered in this version of the model. The dissolved elements are O2, SO4 2-, H2, CH3COOH, and CH4. Methane is dissolved in water or present as a free phase if its concentration exceeds its solubility at given pressure and temperature. In this microscopic model, the transformation of substrate into biomass is described through a set of logistic equations coupled with the transport equations (advection and diffusion). Based on the microscopic considerations we developed the macroscopic model of low maturity/biogenic gas generation in which hydrocarbons are generated through first order kinetic reactions at low maturity. This macroscopic model is adapted to petroleum system modeling at basin scale with TemisFlow®, which aims to understand and predict hydrocarbon generation, migration, and accumulation. It is composed of: i) A source rock criteria which allow defining the biogenic gas source rocks potential and ii) A kinetic model of methane generation. The previous model has been successfully applied on different basins such as the Carupano Basin from the offshore Venezuela, the Magdalena Delta (offshore Colombia) and the offshore Vietnam where direct observations of low-maturity gas were available. Furthermore, it has been applied in the offshore Lebanon in order to check the viability of

  3. Model of Gas Flow Through Porous Refractory Applied to an Upper Tundish Nozzle

    Science.gov (United States)

    Liu, Rui; Thomas, Brian G.

    2015-02-01

    Argon gas commonly is injected into the liquid metal stream through the porous refractory walls in many metallurgical processes. In this work, a new model has been developed to investigate gas diffusion through heated porous refractory, including the effects of refractory geometry, the thermal expansion of the gas, temperature-dependent gas viscosity, and possible leakage into unsealed joints. A novel one-way-flow pressure boundary condition has been formulated and implemented to prevent unrealistic flow into the refractory. The complete model is validated with both analytical solutions of 1D test problems and observations of a water bubbling experiment. Then, to demonstrate practical application of this general model, argon gas flow is simulated through a double-slitted upper tundish nozzle during continuous steel casting with a slide-gate system. Realistic liquid steel pressure distributions with the bubbling threshold condition are applied on the inner surface. Parametric studies are conducted to investigate the effects of joint gas leakage, refractory conductivity, permeability, and injection pressure on the resulting gas distributions, gas mass flow rates, and leakage fraction. This new model of porous flow can serve as the first step of a comprehensive multiphase model system.

  4. Topiramate Induced Excessive Sialorrhea

    Directory of Open Access Journals (Sweden)

    Ersel Dag

    2015-11-01

    Full Text Available It is well-known that drugs such as clozapine and lithium can cause sialorrhea. On the other hand, topiramate has not been reported to induce sialorrhea. We report a case of a patient aged 26 who was given antiepileptic and antipsychotic drugs due to severe mental retardation and intractable epilepsy and developed excessive sialorrhea complaint after the addition of topiramate for the control of seizures. His complaints continued for 1,5 years and ended after giving up topiramate. We presented this case since it was a rare sialorrhea case induced by topiramate. Clinicians should be aware of the possibility of sialorrhea development which causes serious hygiene and social problems when they want to give topiramate to the patients using multiple drugs.

  5. Abundance, Excess, Waste

    Directory of Open Access Journals (Sweden)

    Rox De Luca

    2016-02-01

    Her recent work focuses on the concepts of abundance, excess and waste. These concerns translate directly into vibrant and colourful garlands that she constructs from discarded plastics collected on Bondi Beach where she lives. The process of collecting is fastidious, as is the process of sorting and grading the plastics by colour and size. This initial gathering and sorting process is followed by threading the components onto strings of wire. When completed, these assemblages stand in stark contrast to the ease of disposability associated with the materials that arrive on the shoreline as evidence of our collective human neglect and destruction of the environment around us. The contrast is heightened by the fact that the constructed garlands embody the paradoxical beauty of our plastic waste byproducts, while also evoking the ways by which those byproducts similarly accumulate in randomly assorted patterns across the oceans and beaches of the planet.

  6. Modelling of landfill gas adsorption with bottom ash for utilization of renewable energy

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Chen

    2011-10-06

    Energy crisis, environment pollution and climate change are the serious challenges to people worldwide. In the 21st century, human being is trend to research new technology of renewable energy, so as to slow down global warming and develop society in an environmentally sustainable method. Landfill gas, produced by biodegradable municipal solid waste in landfill, is a renewable energy source. In this work, landfill gas utilization for energy generation is introduced. Landfill gas is able to produce hydrogen by steam reforming reactions. There is a steam reformer equipment in the fuel cells system. A sewage plant of Cologne in Germany has run the Phosphoric Acid Fuel Cells power station with biogas for more than 50,000 hours successfully. Landfill gas thus may be used as fuel for electricity generation via fuel cells system. For the purpose of explaining the possibility of landfill gas utilization via fuel cells, the thermodynamics of landfill gas steam reforming are discussed by simulations. In practice, the methane-riched gas can be obtained by landfill gas purification and upgrading. This work investigate a new method for upgrading-landfill gas adsorption with bottom ash experimentally. Bottom ash is a by-product of municipal solid waste incineration, some of its physical and chemical properties are analysed in this work. The landfill gas adsorption experimental data show bottom ash can be used as a potential adsorbent for landfill gas adsorption to remove CO{sub 2}. In addition, the alkalinity of bottom ash eluate can be reduced in these adsorption processes. Therefore, the interactions between landfill gas and bottom ash can be explained by series reactions accordingly. Furthermore, a conceptual model involving landfill gas adsorption with bottom ash is developed. In this thesis, the parameters of landfill gas adsorption equilibrium equations can be obtained by fitting experimental data. On the other hand, these functions can be deduced with theoretical approach

  7. Simulation of Water Level Fluctuations in a Hydraulic System Using a Coupled Liquid-Gas Model

    Directory of Open Access Journals (Sweden)

    Chao Wang

    2015-08-01

    Full Text Available A model for simulating vertical water level fluctuations with coupled liquid and gas phases is presented. The Preissmann implicit scheme is used to linearize the governing equations for one-dimensional transient flow for both liquid and gas phases, and the linear system is solved using the chasing method. Some classical cases for single liquid and gas phase transients in pipelines and networks are studied to verify that the proposed methods are accurate and reliable. The implicit scheme is extended using a dynamic mesh to simulate the water level fluctuations in a U-tube and an open surge tank without consideration of the gas phase. Methods of coupling liquid and gas phases are presented and used for studying the transient process and interaction between the phases, for gas phase limited in a chamber and gas phase transported in a pipeline. In particular, two other simplified models, one neglecting the effect of the gas phase on the liquid phase and the other one coupling the liquid and gas phases asynchronously, are proposed. The numerical results indicate that the asynchronous model performs better, and are finally applied to a hydropower station with surge tanks and air shafts to simulate the water level fluctuations and air speed.

  8. Suzaku observations of X-ray excess emission in the cluster of galaxies A3112

    CERN Document Server

    Lehto, T; Bonamente, M; Ota, N; Kaastra, J

    2010-01-01

    We analysed the Suzaku XIS1 data of the A3112 cluster of galaxies in order to examine the X-ray excess emission in this cluster reported earlier with the XMM-Newton and Chandra satellites. The best-fit temperature of the intracluster gas depends strongly on the choice of the energy band used for the spectral analysis. This proves the existence of excess emission component in addition to the single-temperature MEKAL in A3112. We showed that this effect is not an artifact due to uncertainties of the background modeling, instrument calibration or the amount of Galactic absorption. Neither does the PSF scatter of the emission from the cool core nor the projection of the cool gas in the cluster outskirts produce the effect. Finally we modeled the excess emission either by using an additional MEKAL or powerlaw component. Due to the small differencies between thermal and non-thermal model we can not rule out the non-thermal origin of the excess emission based on the goodness of the fit. Assuming that it has a therma...

  9. A Mathematical Model of Gas-Turbine Pump Complex

    Science.gov (United States)

    Shpilevoy, V. A.; Chekardovsky, S. M.; Zakirazkov, A. G.

    2016-10-01

    The articles analyzes the state of an extensive network of main oil pipelines of Tyumen region on the basis of statistical data, and also suggest ways of improving the efficiency of energy-saving policy on the main transport oil. Various types of main oil pipelines pump drives were examined. It was determined that now there is no strict analytical dependence between main operating properties of the power turbine of gas turbine engine. At the same time it is necessary to determine the operating parameters using a turbine at GTPU, interconnection between power and speed frequency, as well as the feasibility of using a particular mode. Analysis of foreign experience, the state of domestic enterprises supplying the country with gas turbines, features of the further development of transport of hydrocarbon resources allows us to conclude the feasibility of supplying the oil transportation industry of our country with pumping units based on gas turbine drive.

  10. Excessive astrocyte-derived neurotrophin-3 contributes to the abnormal neuronal dendritic development in a mouse model of fragile X syndrome.

    Directory of Open Access Journals (Sweden)

    Qi Yang

    Full Text Available Fragile X syndrome (FXS is a form of inherited mental retardation in humans that results from expansion of a CGG repeat in the Fmr1 gene. Recent studies suggest a role of astrocytes in neuronal development. However, the mechanisms involved in the regulation process of astrocytes from FXS remain unclear. In this study, we found that astrocytes derived from a Fragile X model, the Fmr1 knockout (KO mouse which lacks FMRP expression, inhibited the proper elaboration of dendritic processes of neurons in vitro. Furthermore, astrocytic conditioned medium (ACM from KO astrocytes inhibited proper dendritic growth of both wild-type (WT and KO neurons. Inducing expression of FMRP by transfection of FMRP vectors in KO astrocytes restored dendritic morphology and levels of synaptic proteins. Further experiments revealed elevated levels of the neurotrophin-3 (NT-3 in KO ACM and the prefrontal cortex of Fmr1 KO mice. However, the levels of nerve growth factor (NGF, brain-derived neurotrophic factor (BDNF, glial cell-derived neurotrophic factor (GDNF, and ciliary neurotrophic factor (CNTF were normal. FMRP has multiple RNA-binding motifs and is involved in translational regulation. RNA-binding protein immunoprecipitation (RIP showed the NT-3 mRNA interacted with FMRP in WT astrocytes. Addition of high concentrations of exogenous NT-3 to culture medium reduced the dendrites of neurons and synaptic protein levels, whereas these measures were ameliorated by neutralizing antibody to NT-3 or knockdown of NT-3 expression in KO astrocytes through short hairpin RNAs (shRNAs. Prefrontal cortex microinjection of WT astrocytes or NT-3 shRNA infected KO astrocytes rescued the deficit of trace fear memory in KO mice, concomitantly decreased the NT-3 levels in the prefrontal cortex. This study indicates that excessive NT-3 from astrocytes contributes to the abnormal neuronal dendritic development and that astrocytes could be a potential therapeutic target for FXS.

  11. Excessive astrocyte-derived neurotrophin-3 contributes to the abnormal neuronal dendritic development in a mouse model of fragile X syndrome.

    Science.gov (United States)

    Yang, Qi; Feng, Bin; Zhang, Kun; Guo, Yan-yan; Liu, Shui-bing; Wu, Yu-mei; Li, Xiao-qiang; Zhao, Ming-gao

    2012-01-01

    Fragile X syndrome (FXS) is a form of inherited mental retardation in humans that results from expansion of a CGG repeat in the Fmr1 gene. Recent studies suggest a role of astrocytes in neuronal development. However, the mechanisms involved in the regulation process of astrocytes from FXS remain unclear. In this study, we found that astrocytes derived from a Fragile X model, the Fmr1 knockout (KO) mouse which lacks FMRP expression, inhibited the proper elaboration of dendritic processes of neurons in vitro. Furthermore, astrocytic conditioned medium (ACM) from KO astrocytes inhibited proper dendritic growth of both wild-type (WT) and KO neurons. Inducing expression of FMRP by transfection of FMRP vectors in KO astrocytes restored dendritic morphology and levels of synaptic proteins. Further experiments revealed elevated levels of the neurotrophin-3 (NT-3) in KO ACM and the prefrontal cortex of Fmr1 KO mice. However, the levels of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), and ciliary neurotrophic factor (CNTF) were normal. FMRP has multiple RNA-binding motifs and is involved in translational regulation. RNA-binding protein immunoprecipitation (RIP) showed the NT-3 mRNA interacted with FMRP in WT astrocytes. Addition of high concentrations of exogenous NT-3 to culture medium reduced the dendrites of neurons and synaptic protein levels, whereas these measures were ameliorated by neutralizing antibody to NT-3 or knockdown of NT-3 expression in KO astrocytes through short hairpin RNAs (shRNAs). Prefrontal cortex microinjection of WT astrocytes or NT-3 shRNA infected KO astrocytes rescued the deficit of trace fear memory in KO mice, concomitantly decreased the NT-3 levels in the prefrontal cortex. This study indicates that excessive NT-3 from astrocytes contributes to the abnormal neuronal dendritic development and that astrocytes could be a potential therapeutic target for FXS.

  12. Histological and immunohistological analysis of degenerative changes in the cranial cruciate ligament in a canine model of excessive tibial plateau angle.

    Science.gov (United States)

    Ichinohe, T; Kanno, N; Harada, Y; Yogo, T; Tagawa, M; Hara, Y

    2015-01-01

    To create a canine model of excessive tibial plateau angle (eTPA) and assess the chondroid metaplasia and extracellular matrix alteration in the cranial cruciate ligament. Seven mature female Beagles were included. Cylindrical osteotomy was performed bilaterally in the proximal tibia. The TPA was increased to approximately 40° in the left tibia (eTPA stifle) and left unchanged in the right tibia (control stifle). Exercise stress was started at three months postoperatively, and at 12 months postoperatively the dogs were euthanatized and the cranial cruciate ligaments were collected. The specimens were subjected to haematoxylin and eosin staining to assess the ligamentocyte morphology and immunostaining to assess the type I (COLI), type II (COLII), and type III (COLIII) collagen, and the sry-type HMG box 9 (SOX9) staining. Macroscopic cranial cruciate ligament injury was absent in six dogs but present in the eTPA stifle of one dog, which was excluded from the analysis. The ligamentocyte density decreased and the percentage of round ligamentocytes increased in the eTPA stifles. The COLII, COLIII, and SOX9 staining increased significantly and COLI deposition decreased in the eTPA stifles compared to the control stifle. The extracellular matrix changed, COLI deposition decreased, and COLIII and SOX9 staining increased in the cranial cruciate ligament of the eTPA stifles. SOX9 may contribute to COLII synthesis in the extracellular matrix of the cranial cruciate ligament in eTPA stifles, and eTPA may promote chondroid metaplasia and extracellular matrix alteration.

  13. Suzaku observations of X-ray excess emission in the cluster of galaxies A 3112

    Science.gov (United States)

    Lehto, T.; Nevalainen, J.; Bonamente, M.; Ota, N.; Kaastra, J.

    2010-12-01

    Aims: We analysed the Suzaku XIS1 data of the A 3112 cluster of galaxies in order to examine the X-ray excess emission in this cluster reported earlier with the XMM-Newton and Chandra satellites. Methods: We performed X-ray spectroscopy on the data of a single large region. We carried out simulations to estimate the systematic uncertainties affecting the X-ray excess signal. Results: The best-fit temperature of the intracluster gas depends strongly on the choice of the energy band used for the spectral analysis. This proves the existence of excess emission component in addition to the single-temperature MEKAL in A 3112. We showed that this effect is not an artifact due to uncertainties of the background modeling, instrument calibration or the amount of Galactic absorption. Neither does the PSF scatter of the emission from the cool core nor the projection of the cool gas in the cluster outskirts produce the effect. Finally we modeled the excess emission either by using an additional MEKAL or powerlaw component. Due to the small differencies between thermal and non-thermal model we can not rule out the non-thermal origin of the excess emission based on the goodness of the fit. Assuming that it has a thermal origin, we further examined the differential emission measure (DEM) models. We utilised two different DEM models, a Gaussian differential emission measure distribution (GDEM) and WDEM model, where the emission measure of a number of thermal components is distributed as a truncated power law. The best-fit XIS1 MEKAL temperature for the 0.4-7.0 keV band is 4.7 ± 0.1 keV, consistent with that obtained using GDEM and WDEM models.

  14. Computational modeling of Krypton gas puffs with tailored mass density profiles on Z

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, C. A.; Ampleford, D. J.; Lamppa, D. C.; Hansen, S. B.; Jones, B.; Harvey-Thompson, A. J.; Jobe, M.; Strizic, T.; Reneker, J.; Rochau, G. A.; Cuneo, M. E. [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185 (United States)

    2015-05-15

    Large diameter multi-shell gas puffs rapidly imploded by high current (∼20 MA, ∼100 ns) on the Z generator of Sandia National Laboratories are able to produce high-intensity Krypton K-shell emission at ∼13 keV. Efficiently radiating at these high photon energies is a significant challenge which requires the careful design and optimization of the gas distribution. To facilitate this, we hydrodynamically model the gas flow out of the nozzle and then model its implosion using a 3-dimensional resistive, radiative MHD code (GORGON). This approach enables us to iterate between modeling the implosion and gas flow from the nozzle to optimize radiative output from this combined system. Guided by our implosion calculations, we have designed gas profiles that help mitigate disruption from Magneto-Rayleigh–Taylor implosion instabilities, while preserving sufficient kinetic energy to thermalize to the high temperatures required for K-shell emission.

  15. An Explosive Range Model Based on the Gas Composition, Temperature, and Pressure during Air Drilling

    Directory of Open Access Journals (Sweden)

    Xiangyu Fan

    2016-01-01

    Full Text Available Air drilling is low cost and effectively improves the penetration rate and causes minimal damage to liquid-sensitive pay zones. However, there is a potential downhole explosion when combustible gas mixed with drilling fluid reaches the combustible condition. In this paper, based on the underground combustion mechanism, an explosive range calculation model is established. This model couples the state equation and the empirical formula method, which considers the inert gas content, pressure, mixed gas component, and temperature. The result shows that increase of the inert gas content narrows the explosive range, while increase of the gas temperature and pressure improves the explosive range. A case in Chongqing, China, is used to validate the explosive range calculation model.

  16. Macroscopic dynamics of incoherent soliton ensembles: soliton-gas kinetics and direct numerical modeling

    CERN Document Server

    Carbone, Francesco; El, Gennady

    2015-01-01

    We undertake a detailed comparison of the results of direct numerical simulations of the integrable soliton gas dynamics with the analytical predictions inferred from the exact solutions of the relevant kinetic equation for solitons. We use the KdV soliton gas as a simplest analytically accessible model yielding major insight into the general properties of soliton gases in integrable systems. Two model problems are considered: (i) the propagation of a `trial' soliton through a one-component `cold' soliton gas consisting of randomly distributed solitons of approximately the same amplitude; and (ii) collision of two cold soliton gases of different amplitudes (soliton gas shock tube problem) leading to the formation of an incoherend dispersive shock wave. In both cases excellent agreement is observed between the analytical predictions of the soliton gas kinetics and the direct numerical simulations. Our results confirm relevance of the kinetic equation for solitons as a quantitatively accurate model for macrosco...

  17. Phytic Acid Protects against 6-Hydroxydopamine-Induced Dopaminergic Neuron Apoptosis in Normal and Iron Excess Conditions in a Cell Culture Model.

    Science.gov (United States)

    Xu, Qi; Kanthasamy, Anumantha G; Reddy, Manju B

    2011-02-07

    Iron may play an important role in Parkinson's disease (PD) since it can induce oxidative stress-dependent neurodegeneration. The objective of this study was to determine whether the iron chelator, phytic acid (IP6) can protect against 6-hydroxydopamine- (6-OHDA-) induced apoptosis in immortalized rat mesencephalic dopaminergic cells under normal and iron-excess conditions. Caspase-3 activity was increased about 6-fold after 6-OHDA treatment (compared to control; P IP6 pretreatment decreased it by 38% (P IP6 pretreatment. Under iron-excess condition, a 6-fold increase in caspase-3 activity (P IP6. Together, our data suggest that IP6 protects against 6-OHDA-induced cell apoptosis in both normal and iron-excess conditions, and IP6 may offer neuroprotection in PD.

  18. Development and test of an evaluation protocol for heavy gas dispersion models

    NARCIS (Netherlands)

    Duijm, N.J.; Carissimo, B.; Mercer, A.; Bartholome, C.; Giesbrecht, H.

    1997-01-01

    In order to improve the quality (i.e. fitness-for-purpose) of models used to describe the atmospheric dispersion of heavy gas, an evaluation methodology has been developed and tested through a small evaluation exercise. This activity was carried out by the Heavy Gas Dispersion Expert Group, which wa

  19. Mathematical model of diffusion-limited gas bubble dynamics in unstirred tissue with finite volume.

    Science.gov (United States)

    Srinivasan, R Srini; Gerth, Wayne A; Powell, Michael R

    2002-02-01

    Models of gas bubble dynamics for studying decompression sickness have been developed by considering the bubble to be immersed in an extravascular tissue with diffusion-limited gas exchange between the bubble and the surrounding unstirred tissue. In previous versions of this two-region model, the tissue volume must be theoretically infinite, which renders the model inapplicable to analysis of bubble growth in a finite-sized tissue. We herein present a new two-region model that is applicable to problems involving finite tissue volumes. By introducing radial deviations to gas tension in the diffusion region surrounding the bubble, the concentration gradient can be zero at a finite distance from the bubble, thus limiting the tissue volume that participates in bubble-tissue gas exchange. It is shown that these deviations account for the effects of heterogeneous perfusion on gas bubble dynamics, and are required for the tissue volume to be finite. The bubble growth results from a difference between the bubble gas pressure and an average gas tension in the surrounding diffusion region that explicitly depends on gas uptake and release by the bubble. For any given decompression, the diffusion region volume must stay above a certain minimum in order to sustain bubble growth.

  20. Molecular interpretation of nonclassical gas dynamics of dense vapors under the van der Waals model

    NARCIS (Netherlands)

    Colonna, P.; Guardone, A.

    2006-01-01

    The van der Waals polytropic gas model is used to investigate the role of attractive and repulsive intermolecular forces and the influence of molecular complexity on the possible nonclassical gas dynamic behavior of vapors near the liquid-vapor saturation curve. The decrease of the sound speed upon

  1. Models for Gas Hydrate-Bearing Sediments Inferred from Hydraulic Permeability and Elastic Velocities

    Science.gov (United States)

    Lee, Myung W.

    2008-01-01

    Elastic velocities and hydraulic permeability of gas hydrate-bearing sediments strongly depend on how gas hydrate accumulates in pore spaces and various gas hydrate accumulation models are proposed to predict physical property changes due to gas hydrate concentrations. Elastic velocities and permeability predicted from a cementation model differ noticeably from those from a pore-filling model. A nuclear magnetic resonance (NMR) log provides in-situ water-filled porosity and hydraulic permeability of gas hydrate-bearing sediments. To test the two competing models, the NMR log along with conventional logs such as velocity and resistivity logs acquired at the Mallik 5L-38 well, Mackenzie Delta, Canada, were analyzed. When the clay content is less than about 12 percent, the NMR porosity is 'accurate' and the gas hydrate concentrations from the NMR log are comparable to those estimated from an electrical resistivity log. The variation of elastic velocities and relative permeability with respect to the gas hydrate concentration indicates that the dominant effect of gas hydrate in the pore space is the pore-filling characteristic.

  2. Geochemical modelling of hydrogen gas migration in an unsaturated bentonite buffer

    NARCIS (Netherlands)

    Sedighi, M.; Thomas, H.R.; Al Masum, S.; Vardon, P.J.; Nicholson, D.; Chen, Q.

    2014-01-01

    This paper presents an investigation of the transport and fate of hydrogen gas through compacted bentonite buffer. Various geochemical reactions that may occur in the multiphase and multicomponent system of the unsaturated bentonite buffer are considered. A reactive gas transport model, developed

  3. Molecular interpretation of nonclassical gas dynamics of dense vapors under the van der Waals model

    NARCIS (Netherlands)

    Colonna, P.; Guardone, A.

    2006-01-01

    The van der Waals polytropic gas model is used to investigate the role of attractive and repulsive intermolecular forces and the influence of molecular complexity on the possible nonclassical gas dynamic behavior of vapors near the liquid-vapor saturation curve. The decrease of the sound speed upon

  4. MATHEMATIC MODELING IN ANALYSIS OF BIO-GAS PURIFICATION FROM CARBON DIOXIDE

    Directory of Open Access Journals (Sweden)

    Y. A. Losiouk

    2009-01-01

    Full Text Available The paper considers a possibility to involve bio-gas generated at testing grounds of hard domestic garbage in power supply system in the Republic of Belarus. An example of optimization using mathematical modeling of plant operation which is used for bio-gas enrichment is given in the paper. 

  5. Geochemical modelling of hydrogen gas migration in an unsaturated bentonite buffer

    NARCIS (Netherlands)

    Sedighi, M.; Thomas, H.R.; Al Masum, S.; Vardon, P.J.; Nicholson, D.; Chen, Q.

    2014-01-01

    This paper presents an investigation of the transport and fate of hydrogen gas through compacted bentonite buffer. Various geochemical reactions that may occur in the multiphase and multicomponent system of the unsaturated bentonite buffer are considered. A reactive gas transport model, developed wi

  6. Relationship between in situ degradation kinetics and in vitro gas production fermentation using different mathematical models

    NARCIS (Netherlands)

    Rodrigues, M.A.M.; Cone, J.W.; Ferreira, L.M.M.; Blok, M.C.; Guedes, C.

    2009-01-01

    In vitro and in situ studies were conducted to evaluate the influence of different mathematical models, used to fit gas production profiles of 15 feedstuffs, on estimates of nylon bag organic matter (OM) degradation kinetics. The gas production data were fitted to Exponential, Logistic, Gompertz and

  7. Geochemical modelling of hydrogen gas migration in an unsaturated bentonite buffer

    NARCIS (Netherlands)

    Sedighi, M.; Thomas, H.R.; Al Masum, S.; Vardon, P.J.; Nicholson, D.; Chen, Q.

    2014-01-01

    This paper presents an investigation of the transport and fate of hydrogen gas through compacted bentonite buffer. Various geochemical reactions that may occur in the multiphase and multicomponent system of the unsaturated bentonite buffer are considered. A reactive gas transport model, developed wi

  8. A simple model of gas flow in a porous powder compact.

    Energy Technology Data Exchange (ETDEWEB)

    Shugard, Andrew D.; Robinson, David B.

    2014-04-01

    This report describes a simple model for ideal gas flow from a vessel through a bed of porous material into another vessel. It assumes constant temperature and uniform porosity. Transport is treated as a combination of viscous and molecular flow, with no inertial contribution (low Reynolds number). This model can be used to fit data to obtain permeability values, determine flow rates, understand the relative contributions of viscous and molecular flow, and verify volume calibrations. It draws upon the Dusty Gas Model and other detailed studies of gas flow through porous media.

  9. A Simple Model of Gas Flow in a Porous Powder Compact

    Energy Technology Data Exchange (ETDEWEB)

    Shugard, Andrew D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Robinson, David [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2012-07-01

    This report describes a simple model for ideal gas flow from a vessel through a bed of porous material into another vessel. It assumes constant temperature and uniform porosity. Transport is treated as a combination of viscous and molecular flow, with no inertial contribution (low Reynolds number). This model can be used to fit data to obtain permeability values, determine flow rates, understand the relative contributions of viscous and molecular flow, and verify volume calibrations. It draws upon the Dusty Gas Model and other detailed studies of gas flow through porous media.

  10. V819 Tau: A Rare Weak-Lined T Tauri Star with a Weak Infrared Excess

    CERN Document Server

    Furlan, E; Sargent, B A; Manoj, P; Kim, K H; Watson, Dan M

    2009-01-01

    We use Spitzer data to infer that the small infrared excess of V819 Tau, a weak-lined T Tauri star in Taurus, is real and not attributable to a "companion" 10 arcsec to the south. We do not confirm the mid-infrared excess in HBC 427 and V410 X-ray 3, which are also non-accreting T Tauri stars in the same region; instead, for the former object, the excess arises from a red companion 9 arcsec to the east. A single-temperature blackbody fit to the continuum excess of V819 Tau implies a dust temperature of 143 K; however, a better fit is achieved when the weak 10 and 20 micron silicate emission features are also included. We infer a disk of sub-micron silicate grains between about 1 AU and several 100 AU with a constant surface density distribution. The mid-infrared excess of V819 Tau can be successfully modeled with dust composed mostly of small amorphous olivine grains at a temperature of 85 K, and most of the excess emission is optically thin. The disk could still be primordial, but gas-poor and therefore shor...

  11. Conductivity modeling of gas sensors based on copper ...

    African Journals Online (AJOL)

    Technol., Synthèse 34 : 18 -27 (2017) .... selectivity, low threshold, good resolution and weak response times), gas analyzers are not ... Its health hazards are well-established: above 80 ppb, respiratory troubles begin to be acute [10]. In ..... [10] International Center for Technology Assessment, In-Car Air Pollution: the Hidden ...

  12. Adhesion of solid particles to gas bubbles. Part 1: Modelling

    NARCIS (Netherlands)

    Omota, Florin; Dimian, Alexandre C.; Bliek, A.

    2006-01-01

    Particle-to-bubble adhesion is important in the areas of anti-foaming, in flotation processes and in multiphase slurry reactors. In the present work we particularly address the latter. The behaviour of fine catalyst particles adhering to gas bubbles in aqueous media is governed by the surface

  13. SIMPLODE: An Imploding Gas Puff Plasma Model. I. Neon.

    Science.gov (United States)

    2014-09-26

    cylindrical annular gas puff plasma of uniform density carrying a uniform current in the Z- direction. Only the radial motion is considered - hence...suggest that the relationship between current and yield is a linear one, because it is not, it is only indicative that in general, for optimum kinematics

  14. 3D numerical modeling of shale gas stimulation and seisimicity

    NARCIS (Netherlands)

    Shahid, A.S.; Wassing, B.B.T.; Verga, F.; Fokker, P.A.

    2013-01-01

    The economic production from shale gas reservoir depends on the success of hydraulic stimulation, which is aimed at the creation of a permeable complex fracture network. This is achieved by the reactivation of a natural fracture network; however, the reactivation may be accompanied by unwanted seism

  15. Computational fluid dynamics model of the spinning pipe gas lens

    CSIR Research Space (South Africa)

    Mafusire, C

    2010-08-01

    Full Text Available When a metal horizontal pipe is heated and spun along its axis, a graded refractive index distribution is generated which is can be used as a lens, thus its name, the spinning pipe gas lens (SPGL). Previous experimental results of its performance...

  16. Design and off-design thermodynamic model of a gas turbine for performance prediction

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, Ulisses A. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Ensaios de Modelos de Engenharia (LEME)]. E-mail: ulisses@peno.coppe.ufrj.br; Belchior, Carlos Rodrigues Pereira [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE). Lab. de Maquinas Termicas (LMT)]. E-mail: belchior@peno.coppe.ufrj.br

    2008-07-01

    There are some types of faults that do not leave 'signatures' in the vibration spectrum of a gas turbine. These faults can only be detected by other analysis techniques. One of these techniques is the gas turbine performance analysis or gas path analysis which relates the efficiency, mass flow, temperature, pressure, fuel consumption and power to the gas turbine faults. In this paper the methodology used in the development of a thermodynamic model that simulates the design and off-design operation of a gas turbine with a free power turbine will be presented. The results obtained are used to predict the gas turbine performance in both design and off-design operation point, and also to simulate some types of faults. (author)

  17. Relating landfill gas emissions to atmospheric pressure using numerical modeling and state-space analysis

    DEFF Research Database (Denmark)

    Poulsen, T.G.; Christophersen, Mette; Moldrup, P.

    2003-01-01

    were applied: (I) State-space analysis was used to identify relations between gas flux and short-term (hourly) variations in atmospheric pressure. (II) A numerical gas transport model was fitted to the data and used to quantify short-term impacts of variations in atmospheric pressure, volumetric soil......-water content, soil gas permeability, soil gas diffusion coefficients, and biological CH4 degradation rate upon landfill gas concentration and fluxes in the soil. Fluxes and concentrations were found to be most sensitive to variations in volumetric soil water content, atmospheric pressure variations and gas...... permeability whereas variations in CH4 oxidation rate and molecular coefficients had less influence. Fluxes appeared to be most sensitive to atmospheric pressure at intermediate distances from the landfill edge. Also overall CH4 fluxes out of the soil over longer periods (years) were largest during periods...

  18. ECONOMETRIC MODELING OF THE DYNAMICS OF VOLUMES HYDROCARBONS OF SMALL OIL AND GAS ENTERPRISES

    Directory of Open Access Journals (Sweden)

    GORLOV A.V.

    2015-01-01

    Full Text Available In this paper investigates the principles of functioning of small oil and gas enterprises of Russia. The basic characteristics and socio-economic tasks performed by the small oil and gas enterprises. Made correlation and regression analysis, a result of which the pair correlation coefficients between the indicator of development of small oil and gas enterprises (volumes hydrocarbons and the factors that characterize the work environment of their operation; built regressions, describing the process of development of small oil and gas enterprises. With a view to forecasting the development of small oil and gas enterprises built production function of Cobb-Douglas and selected econometric model, has good predictive properties. Made predictive calculations dynamics of volumes hydrocarbons of small oil and gas enterprises on formulating scenarios for the planning period (2015-2016 years.

  19. Disequilibrium econometrics. An application to modelling of the natural gas market in the USA

    Energy Technology Data Exchange (ETDEWEB)

    Barret, C.

    1990-08-01

    Econometrics methods applicable to limited dependent variable models are presented. Qualitative models are briefly reported, TOBIT models and disequilibrium models are developed. The different formulations are used for simulating the gas market in the USA. Evolution and regulations of this market are reported and an approach by disequilibrium is developed.

  20. Computing excess functions of ionic solutions: the smaller-ion shell model versus the primitive model. 2. Ion-size parameters.

    Science.gov (United States)

    Fraenkel, Dan

    2015-01-13

    A recent Monte Carlo (MC) simulation study of the primitive model (PM) of ionic solutions ( Abbas, Z. et al. J. Phys. Chem. B 2009 , 113 , 5905 ) has resulted in an extensive "mapping" of real aqueous solutions of 1-1, 2-1, and 3-1 binary electrolytes and a list of "recommended ionic radii" for many ions. For the smaller cations, the model-experiment fitting process gave much larger radii than the respective crystallographic radii, and those cations were therefore claimed to be hydrated. In Part 1 (DOI 10.1021/ct5006938 ) of the present work, the above study for the unrestricted PM - dubbed MC-UPM - has been confronted with the Smaller-ion Shell (SiS) treatment ( Fraenkel, D. Mol. Phys. 2010 , 108 , 1435 ), or "DH-SiS", by comparing the range and quality of model-experiment fits of the mean ionic activity coefficient as a function of ionic concentration. Here I compare the ion-size parameters (ISPs) of "best fit" of the two models and argue that since ISPs derived from DH-SiS are identical with (or close to) crystallographic or thermochemical ionic diameters for both cations and anions, and they do not depend on the counterion - they are more reliable, as physicochemical entities, than the PM-derived "recommended ionic radii".