The generalized Chaplygin-Jacobi gas
Villanueva, J R
2015-01-01
The present paper is devoted to find a new generalization of the generalized Chaplygin gas. Therefore, starting from the Hubble parameter associated to the Chaplygin scalar field and using some elliptic identities, the elliptic generalization is straightforward. Thus, all relevant quantities that drive inflation are calculated exactly. Finally, using the measurement on inflation from the Planck 2015 results, observational constraints on the parameters are given.
Interacting holographic generalized cosmic Chaplygin gas model
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.
Evolution of Variable Generalized Chaplygin Gas
Institute of Scientific and Technical Information of China (English)
YANG Xiu-Yi; WU Ya-Bo; L(U) Jian-Bo; LI Song
2007-01-01
@@ We consider the variable Generalized Chaplygin gas (VGCG) proposal for unification of dark matter and dark energy with p= pde and ρ = ρdm + ρde. The equation of state of the VGCG is given by p = -A0a-n/ρα, where a is the scale factor.
Extended Analysis on New Generalized Chaplygin Gas
Institute of Scientific and Technical Information of China (English)
WANG Jun; WU Ya-Bo; WANG Di; YANG Wei-Qiang
2009-01-01
We extend the study of the new generalizeal Chaplygin gas (NGCG) based on [J.Cosmol.Astropart.Phys.0601 (2006) 003].Specifically,we not only discuss the change rates of the energy densities and the energy transfer of this model,but also perform the Om diagnostic to differentiate the ACDM model from the NGCG and the GCG models.Furthermore,in order to consider the influence of dark energy on structure formation,we also present the evolution of the growth index in this scenario with interaction.
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.)
Extending the generalized Chaplygin gas model by using geometrothermodynamics
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.
Recent observational constraints on generalized Chaplygin gas in UDME scenario
Thakur, P.
2017-03-01
Recent observational predictions suggest that our Universe is passing through an accelerating phase in the recent past. This acceleration may be realized with the negatively pressured dark energy. Generalized Chaplygin gas may be suitable to describe the evolution of the Universe as a candidate of unified dark matter energy (UDME) model. Its EoS parameters are constrained using (i) dimensionless age parameter ( H 0 t 0) and (ii) the observed Hubble ( H( z)- z) data (OHD) + baryon acoustic oscillation (BAO) data + cosmic microwave background (CMB) shift data + supernovae (Union2.1) data. Dimensionless age parameter puts loose bounds on the EoS parameters. Best-fit values of the EoS parameters H 0, A s and α ( A s and α are defined in the energy density for generalized Chaplygin gas (GCG) and in EoS) are then determined from OHD + BAO + CMB + Union2.1 data and contours are drawn to obtain their allowed range of values. The present age of the Universe ( t 0) and the present Hubble parameter ( H 0) have been estimated with 1 σ confidence level. Best-fit values of deceleration parameter ( q), squared sound speed (cs2) and EoS parameter ( ω) of this model are then determined. It is seen that GCG satisfactorily accommodates an accelerating phase and structure formation phase.
Recent observational constraints on generalized Chaplygin gas in UDME scenario
Indian Academy of Sciences (India)
P THAKUR
2017-03-01
Recent observational predictions suggest that our Universe is passing through an accelerating phase in the recent past. This acceleration may be realized with the negatively pressured dark energy. Generalized Chaplygin gas may be suitable to describe the evolution of the Universe as a candidate of unified dark matterenergy (UDME) model. Its EoS parameters are constrained using (i) dimensionless age parameter ($H_{0}t_{0}$) and (ii) the observed Hubble (H(z) − z) data (OHD) + baryon acoustic oscillation (BAO) data + cosmic microwavebackground (CMB) shift data + supernovae (Union2.1) data. Dimensionless age parameter puts loose bounds on the EoS parameters. Best-fit values of the EoS parameters $H_{0}, A_{s}$ and $\\alpha$ ($A_{s}$ and $\\alpha$ are defined in the energy density for generalized Chaplygin gas (GCG) and in EoS) are then determined from OHD+BAO+CMB+Union2.1 data and contours are drawn to obtain their allowed range of values. The present age of the Universe ($t_0$) and the present Hubble parameter ($H_0$) have been estimated with 1σ confidence level. Best-fit values of deceleration parameter (q), squared sound speed ($c^{2}_{s}$ ) and EoS parameter ($\\omega$) of this model are then determined. It is seen that GCG satisfactorily accommodates an accelerating phase and structure formation phase.
Dissipative generalized Chaplygin gas as phantom dark energy
Energy Technology Data Exchange (ETDEWEB)
Cruz, Norman [Departamento de Fisica, Facultad de Ciencia, Universidad de Santiago, Casilla 307, Santiago (Chile)]. E-mail: ncruz@lauca.usach.cl; Lepe, Samuel [Instituto de Fisica, Facultad de Ciencias Basicas y Matematicas, Pontificia Universidad Catolica de Valparaiso, Avenida Brasil 2950, Valparaiso (Chile)]. E-mail: slepe@ucv.cl; Pena, Francisco [Departamento de Ciencias Fisicas, Facultad de Ingenieria, Ciencias y Administracion, Universidad de la Frontera, Avda. Francisco Salazar 01145, Casilla 54-D, Temuco (Chile)]. E-mail: fcampos@ufro.cl
2007-03-15
The generalized Chaplygin gas, characterized by the equation of state p=-A/{rho}{sup {alpha}}, has been considered as a model for dark energy due to its dark-energy-like evolution at late times. When dissipative processes are taken into account, within the framework of the standard Eckart theory of relativistic irreversible thermodynamics, cosmological analytical solutions are found. Using the truncated causal version of the Israel-Stewart formalism, a suitable model was constructed which crosses the w=-1 barrier. The future-singularities encountered in both approaches are of a new type, and not included in the classification presented by Nojiri and Odintsov [S. Nojiri, S.D. Odintsov, Phys. Rev. D 72 (2005) 023003].
Observational constraints on new generalized Chaplygin gas model
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 ...
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.
Born-Infeld Thin-shell Wormholes Supported by Generalized Cosmic Chaplygin Gas
Azam, M
2016-01-01
This paper investigates thin-shell wormholes in Born-Infeld theory supported by generalized Cosmic Chaplygin gas (GCCG). We study their stability via radial perturbations for distinct values of charge and Born-Infeld parameter. The comparison of wormhole solutions corresponding to generalized Chaplygin gas, modified Chaplygin gas with GCCG quation of state is established. It is found that similar type of wormhole solutions exists for small value of charge and Born-Infeld parameter for all type of equation of state, while some extra stable as well as unstable solution are found corresponding to large value of charge and Born-Infeld parameter. Thus, it is concluded that GCCG and large value of charge may responsible for such extra solutions.
Naji, J.; Karimiyan, K.; Heydari, S.; Amjadi, A.
2014-08-01
Variable viscous generalized cosmic Chaplygin gas (GCCG) was constructed in the presence of cosmological constant and space curvature. Using the numerical analysis we find behavior of some cosmological quantities such as Hubble and deceleration parameters. Observational data is used to fix solution and stability of model is discussed.
Chaplygin gas and effective description of inhomogeneous universe models in general relativity
Energy Technology Data Exchange (ETDEWEB)
Roy, Xavier; Buchert, Thomas, E-mail: roy@obs.univ-lyon1.f, E-mail: buchert@obs.univ-lyon1.f [Universite Lyon 1, Centre de Recherche Astrophysique de Lyon, CNRS UMR 5574, 9 avenue Charles Andre, F-69230 Saint-Genis-Laval (France)
2010-09-07
In the framework of spatially averaged inhomogeneous cosmologies in classical general relativity, effective Einstein equations govern the dynamics of averaged scalar variables in a scale-dependent way. A particular cosmology may be characterized by a cosmic equation of state, closing the hierarchy of effective equations. In this context a natural candidate is provided by the Chaplygin gas, standing for a unified description of dark energy and dark matter. In this paper, we suppose that the inhomogeneous properties of matter and geometry obey the Chaplygin equation of state. The most extreme interpretation assumes that both dark energy and dark matter are not included as additional sources, but are both manifestations of spatial geometrical properties. This feature is an important conceptual difference in comparison with the standard approach of a Friedmann-LemaItre-Robertson-Walker universe filled with dust and another fundamental field characterized by the Chaplygin equation of state. We finally discuss the consequences of the resulting scenario for effective cosmological parameters in order to establish the framework of a future confrontation with observations, and we note that the standard Chaplygin gas may not be ruled out by them.
Cosmological constraints on generalized Chaplygin gas model: Markov Chain Monte Carlo approach
Xu, Lixin; Lu, Jianbo
2010-01-01
We use the Markov Chain Monte Carlo method to investigate a global constraints on the generalized Chaplygin gas (GCG) model as the unification of dark matter and dark energy from the latest observational data: the Constitution dataset of type supernovae Ia (SNIa), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the cosmic microwave background (CMB) data. In a non-flat universe, the constraint results for GCG model are, $\\Ome...
Viscous Generalized Chaplygin Gas Interacting with f(R,T) gravity
Baffou, E H; Houndjo, M J S
2016-01-01
In this paper, we study in Friedmann-Robertson-Walker universe the interaction between the viscous generalized Chaplygin gas with $f(R,T)$ gravity, which is an arbitrary function of the Ricci scalar $R$ and the trace $T$ of the energy-momentum tensor. Assuming that the contents of universe is dominated by a generalized Chaplygin gas and dark energy, we obtained the modified Friedmann equations and also the time dependent energy density and pressure of dark energy due to the shear and bulk viscosities for three interacting models depending on an input parameter $Q$. Within the simple form of scale factor (power-law), we discuss the graphical representation of dark energy density parameter and investigate the shear and bulk viscosities effects on the accelerating expansion of the universe for each interacting model.
Directory of Open Access Journals (Sweden)
Hongjun Cheng
2013-01-01
Full Text Available This paper is devoted to the study of a nonsymmetric Keyfitz-Kranzer system of conservation laws with the generalized and modified Chaplygin gas pressure law, which may admit delta shock waves, a topic of interest. Firstly, we solve the Riemann problems with piecewise constant data having a single discontinuity. For the generalized Chaplygin gas pressure law, the solution consists of three different structures: R+J, S+J, and δ. Existence and uniqueness of delta shock solution are established under the generalized Rankine-Hugoniot relation and entropy condition. For the modified Chaplygin gas pressure law, the structures of solution are R+J and S+J. Secondly, we discuss the limits of Riemann solutions for the modified Chaplygin gas pressure law as the pressure law tends to the generalized Chaplygin gas one. In particular, for some cases, the solution S+J tends to a delta shock wave, and it is different from the delta shock wave for the generalized Chaplygin gas pressure law with the same initial data. Thirdly, we simulate the Riemann solutions and examine the formation process of delta shock wave by employing the Nessyahu-Tadmor scheme. The numerical results are coincident with the theoretical analysis.
Constraints on the generalized Chaplygin gas model from Gamma-ray bursts
Energy Technology Data Exchange (ETDEWEB)
Freitas, R.C., E-mail: rc_freitas@terra.com.br [Grupo de Gravitacao e Cosmologia, Departamento de Fisica, Universidade Federal do Espirito Santo, 29075-910, Vitoria, Espirito Santo (Brazil); Goncalves, S.V.B., E-mail: sergio.vitorino@pq.cnpq.br [Grupo de Gravitacao e Cosmologia, Departamento de Fisica, Universidade Federal do Espirito Santo, 29075-910, Vitoria, Espirito Santo (Brazil); Velten, H.E.S., E-mail: velten@cce.ufes.br [Grupo de Gravitacao e Cosmologia, Departamento de Fisica, Universidade Federal do Espirito Santo, 29075-910, Vitoria, Espirito Santo (Brazil); Fakultaet fuer Physik, Universitaet Bielefeld, Bielefeld 33615 (Germany)
2011-09-14
We study the generalized Chaplygin gas model (GCGM) using Gamma-ray bursts as cosmological probes. In order to avoid the so-called circularity problem we use cosmology-independent data set and Bayesian statistics to impose constraints on the model parameters. We observe that a negative value for the parameter {alpha} is favoured in a flat Universe and the estimated value of the parameter H{sub 0} is lower than that found in literature.
Wormholes admitting conformal Killing vectors and supported by generalized Chaplygin gas
Energy Technology Data Exchange (ETDEWEB)
Kuhfittig, Peter K.F. [Milwaukee School of Engineering, Department of Mathematics, Milwaukee, WI (United States)
2015-08-15
When Morris and Thorne first proposed that traversable wormholes may be actual physical objects, they concentrated on the geometry by specifying the shape and redshift functions. This mathematical approach necessarily raises questions regarding the determination of the required stress-energy tensor. This paper discusses a natural way to obtain a complete wormhole solution by assuming that the wormhole (1) is supported by generalized Chaplygin gas and (2) admits conformal Killing vectors. (orig.)
Reissner-Nordstroem thin-shell wormholes with generalized cosmic Chaplygin gas
Energy Technology Data Exchange (ETDEWEB)
Sharif, M. [University of the Punjab, Department of Mathematics, Lahore (Pakistan); Azam, M. [University of the Punjab, Department of Mathematics, Lahore (Pakistan); University of Education, Division of Science and Technology, Lahore (Pakistan)
2013-09-15
Following Visser's approach (Visser in Phys. Rev. D 39:3182, 1989; Nucl. Phys. B 328:203, 1989; Lorentzian wormholes. AIP Press, New York, 1996) of cut and paste, we construct Reissner-Nordstroem thin-shell wormholes by taking the generalized cosmic Chaplygin gas for the exotic matter located at the wormhole throat. The Darmois-Israel conditions are used to determine the dynamical quantities of the system. The viability of the thin-shell wormholes is explored with respect to radial perturbations preserving the spherical symmetry. We find stable as well as unstable Reissner-Nordstroem thin-shell wormhole solutions depending upon the model parameters. Finally, we compare our results with both generalized and modified Chaplygin gases. (orig.)
Does Chaplygin gas have salvation?
Energy Technology Data Exchange (ETDEWEB)
Campos, Juliano P. [UFRB, Centro de Ciencias Exatas e Tecnologicas, Cruz das Almas, BA (Brazil); Fabris, Julio C.; Perez, Rafael; Piattella, Oliver F. [CCE, UFES, Departamento de Fisica, Vitoria, ES (Brazil); Velten, Hermano [Universitaet Bielefeld, Fakultaet fuer Physik, Postfach 100131, Bielefeld (Germany)
2013-04-15
We investigate the unification scenario provided by the generalized Chaplygin gas model (a perfect fluid characterized by an equation of state p=-A/{rho} {sup {alpha}}). Our concerns lie with a possible tension existing between background kinematic tests and those related to the evolution of small perturbations. We analyze data from the observation of the differential age of the universe, type Ia supernovae, baryon acoustic oscillations, and the position of the first peak of the angular spectrum of the cosmic background radiation. We show that these tests favor negative values of the parameter {alpha}: we find {alpha}= - 0.089{sup +0.161}{sub -0.128} at the 2{sigma} level and that {alpha}<0 with 85 % confidence. These would correspond to negative values of the square speed of sound which are unacceptable from the point of view of structure formation. We discuss a possible solution to this problem, when the generalized Chaplygin gas is framed in the modified theory of gravity proposed by Rastall. We show that a fluid description within this theory does not serve the purpose, but it is necessary to frame the generalized Chaplygin gas in a scalar field theory. Finally, we address the standard general relativistic unification picture provided by the generalized Chaplygin gas in the case {alpha}=0: this is usually considered to be undistinguishable from the standard {Lambda}CDM model, but we show that the evolution of small perturbations, governed by the Meszaros equation, is indeed different and the formation of sub-horizon GCG matter halos may be importantly affected in comparison with the {Lambda}CDM scenario. (orig.)
Warm intermediate inflationary Universe model in the presence of a generalized Chaplygin gas
Energy Technology Data Exchange (ETDEWEB)
Herrera, Ramon [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Valparaiso (Chile); Videla, Nelson [Universidad de Chile, Departamento de Fisica, FCFM, Santiago (Chile); Olivares, Marco [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile)
2016-01-15
A warm intermediate inflationary model in the context of generalized Chaplygin gas is investigated. We study this model in the weak and strong dissipative regimes, considering a generalized form of the dissipative coefficient Γ = Γ(T,φ), and we describe the inflationary dynamics in the slow-roll approximation. We find constraints on the parameters in our model considering the Planck 2015 data, together with the condition for warm inflation T > H, and the conditions for the weak and strong dissipative regimes. (orig.)
Observational constraints on extended Chaplygin gas cosmologies
Indian Academy of Sciences (India)
B C PAUL; P THAKUR; A SAHA
2017-08-01
We investigate cosmological models with extended Chaplygin gas (ECG) as a candidate for dark energy and determine the equation of state parameters using observed data namely, observed Hubble data, baryon acousticoscillation data and cosmic microwave background shift data. Cosmological models are investigated considering cosmic fluid which is an extension of Chaplygin gas, however, it reduces to modified Chaplygin gas (MCG) andalso to generalized Chaplygin gas (GCG) in special cases. It is found that in the case of MCG and GCG, the best-fit values of all the parameters are positive. The distance modulus agrees quite well with the experimental Union2data. The speed of sound obtained in the model is small, necessary for structure formation. We also determine the observational constraints on the constants of the ECG equation.
Study of inflationary generalized cosmic Chaplygin gas for standard and tachyon scalar fields
Energy Technology Data Exchange (ETDEWEB)
Sharif, M.; Saleem, Rabia [University of the Punjab, Department of Mathematics, Lahore (Pakistan)
2014-07-15
We consider an inflationary universe model in the context of the generalized cosmic Chaplygin gas by taking the matter field as standard and tachyon scalar fields. We evaluate the corresponding scalar fields and scalar potentials during the intermediate and logamediate inflationary regimes by modifying the first Friedmann equation. In each case, we evaluate the number of e-folds, scalar as well as tensor power spectra, scalar spectral index, and the important observational parameter, the tensor-scalar ratio in terms of inflation. The graphical behavior of this parameter shows that the model remains incompatible with WMAP7 and Planck observational data in each case. (orig.)
Effects of viscous pressure on warm inflationary generalized cosmic Chaplygin gas model
Energy Technology Data Exchange (ETDEWEB)
Sharif, M.; Saleem, Rabia, E-mail: msharif.math@pu.edu.pk, E-mail: rabiasaleem1988@yahoo.com [Department of Mathematics, University of the Punjab, Quaid-e-Azam Campus, Lahore-54590 (Pakistan)
2014-12-01
This paper is devoted to study the effects of bulk viscous pressure on an inflationary generalized cosmic Chaplygin gas model using FRW background. The matter contents of the universe are assumed to be inflaton and imperfect fluid. We evaluate inflaton fields, potentials and entropy density for variable as well as constant dissipation and bulk viscous coefficients in weak as well as high dissipative regimes during intermediate era. In order to discuss inflationary perturbations, we evaluate entropy density, scalar (tensor) power spectra, their corresponding spectral indices, tensor-scalar ratio and running of spectral index in terms of inflaton which are constrained using recent Planck, WMAP7 and Bicep2 probes.
Study of Inflationary Generalized Cosmic Chaplygin Gas for Standard and Tachyon Scalar Fields
Sharif, M
2014-01-01
We consider an inflationary universe model in the context of generalized cosmic Chaplygin gas by taking matter field as standard and tachyon scalar fields. We evaluate the corresponding scalar fields and scalar potentials during intermediate and logamediate inflationary regimes by modifying the first Friedmann equation. In each case, we evaluate the number of e-folds, scalar as well as tensor power spectra, scalar spectral index and important observational parameter, i.e., tensor-scalar ratio in terms of inflatons. The graphical behavior of this parameter shows that the model remains incompatible with WMAP7 and Planck observational data in each case.
Thin-shell wormholes with a generalized Chaplygin gas in Einstein-Born-Infeld theory
Energy Technology Data Exchange (ETDEWEB)
Eiroa, Ernesto F. [Instituto de Astronomia y Fisica del Espacio, Buenos Aires (Argentina); Universidad de Buenos Aires, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Figueroa Aguirre, Griselda [Instituto de Astronomia y Fisica del Espacio, Buenos Aires (Argentina)
2012-11-15
We construct spherically symmetric thin-shell wormholes supported by a generalized Chaplygin gas in Born-Infeld electrodynamics coupled to Einstein gravity, and we analyze their stability under radial perturbations. For different values of the Born-Infeld parameter and the charge, we compare the results with those obtained in a previous work for Maxwell electrodynamics. The stability region in the parameter space reduces and then disappears as the value of the Born-Infeld parameter is modified in the sense of a larger departure from Maxwell theory. (orig.)
Colistete, R C; Goncalves, S V B
2004-01-01
The type Ia supernovae (SNe Ia) observational data are used to estimate the parameters of a cosmological model with cold dark matter and the generalized Chaplygin gas model (GCGM). The GCGM depends essentially on five parameters: the Hubble constant, the parameter $\\bar{A}$ related to the velocity of the sound, the equation of state parameter $\\alpha$, the curvature of the Universe and the fraction density of the generalized Chaplygin gas (or the cold dark matter). The parameter $\\alpha$ is allowed to take negative values and to be greater than 1. The Bayesian parameter estimation yields $\\alpha = - 0.86^{+6.01}_{-0.15}$, $H_0 = 62.0^{+1.32}_{-1.42} km/Mpc.s$, $\\Omega _{k0}=-1.26_{-1.42}^{+1.32}$, $\\Omega_{m0} = 0.00^{+0.86}_{-0.00}$, $\\Omega_{c0} = 1.39^{+1.21}_{-1.25}$, $\\bar A =1.00^{+0.00}_{-0.39}$, $t_0 = 15.3^{+4.2}_{-3.2}$ and $q_0 = -0.80^{+0.86}_{-0.62}$, where $t_0$ is the age of the Universe and $q_0$ is the value of the deceleration parameter today. Our results indicate that a Universe completely ...
Crossing the phantom divide, the generalized Chaplygin gas and RS braneworlds
García-Compéan, H; Obregón, O; Ramírez, C
2007-01-01
We study the unified generalized Chaplygin gas model in the framework of Randall-Sundrum braneworld, assuming a self-interacting dark energy-matter fluid. We find that a particular splitting of the densities of dark energy and matter (dark and baryonic), allows the possibility that the equation of state for dark energy crosses the phantom divide at the recent epoch. Moreover these densities decay during all the evolution of the Universe, avoiding a Big Rip. We find also a scaling solution such that the ratio of these densities tends asymptotically in the future to a value slightly different than the present one. This could provide an insight towards the solution to the coincidence problem.
Constraining Parameters of Generalized Cosmic Chaplygin Gas in Loop Quantum Cosmology
Ranjit, Chayan
2014-01-01
We have assumed the FRW universe in loop quantum cosmology (LQC) model filled with the dark matter and the Generalized Cosmic Chaplygin gas (GCCG) type dark energy where dark matter follows the linear equation of state. We present the Hubble parameter in terms of the observable parameters $\\Omega_{m0}$ and $H_{0}$ with the redshift $z$ and the other parameters like $A$, $B$, $w_{m}$, $ \\omega$ and $\\alpha$ which coming from our model. From Stern data set (12 points)\\& SNe Type Ia 292 data (from \\cite{Riess1,Riess2,Astier}) we have obtained the bounds of the arbitrary parameters by minimizing the $\\chi^{2}$ test. The best-fit values of the parameters are obtained by 66\\%, 90\\% and 99\\% confidence levels. Next due to joint analysis with Stern+BAO and Stern+BAO+CMB observations, we have also obtained the bounds of the parameters ($A,B$) by fixing some other parameters $\\alpha$, $w_{m}$ and $\\omega$. From the best fit values of the parameters, we have obtained the distance modulus $\\mu(z)$ for our theoretical...
Dynamical Stability and Attractor of the Variable Generalized Chaplygin Gas Model
Institute of Scientific and Technical Information of China (English)
FU Huan-Huan; WU Ya-Bo; CHENG Fang-Yuan
2009-01-01
For the variable generalized Chaplygin gas (VGCG) as a dynamical system,its stability is analyzed and the related dynamical attractors are investigated.By analysis it is shown that there are two critical points corresponding to the matter-dominated phase and the VGCG dark energy-dominated phase,respectively.Moreover,when the parameters n,α and γ take some fixed values,the phase with ωVGCG=-0.92 is a dynamical attractor and the equation of state of VGCG reaches it from either ωVGCG＞-1 or ωVGCG＜-1,independent of the initial values of the dynamical system.This shows a satisfactory cosmological model:the early matter-dominated era,followed by the dark energy-dominated era.Meanwhile,the evolutions of density parameters Ωγ and ΩVGCG are quite different from each other.For different initial values of x and y,Ωγ decreases and flVGCG increases as the time grows,they will eventually approach Ωγ= 0 and ΩVGCG = 1.Furthermore,since different values of n or α may lead to different equation-of-state parameters ωVGC,we also discuss the constraints on the parameters n and α by the observation data.
Does a generalized Chaplygin gas correctly describe the cosmological dark sector?
vom Marttens, R. F.; Casarini, L.; Zimdahl, W.; Hipólito-Ricaldi, W. S.; Mota, D. F.
2017-03-01
Yes, but only for a parameter value that makes it almost coincide with the standard model. We reconsider the cosmological dynamics of a generalized Chaplygin gas (gCg) which is split into a cold dark matter (CDM) part and a dark energy (DE) component with constant equation of state. This model, which implies a specific interaction between CDM and DE, has a ΛCDM limit and provides the basis for studying deviations from the latter. Including matter and radiation, we use the (modified) CLASS code (Blas et al., 2011) to construct the CMB and matter power spectra in order to search for a gCg-based concordance model that is in agreement with the SNIa data from the JLA sample and with recent Planck data. The results reveal that the gCg parameter α is restricted to | α | ≲ 0 . 05, i.e., to values very close to the ΛCDM limit α = 0. This excludes, in particular, models in which DE decays linearly with the Hubble rate.
Naturalness and stability of the generalized Chaplygin gas in the {\\em seesaw cosmon} scenario
Bernardini, Alex E
2010-01-01
The {\\em seesaw} mechanism is conceived on the basis that a mass scale, $\\xi$, and a dimensionless scale, $s$, can be fine-tuned in order to control the dynamics of active and sterile neutrinos through {\\em cosmon}-type equations of motion: the {\\em seesaw cosmon} equations. This allows for sterile neutrinos to be a dark matter candidate. In this scenario, the dynamical masses and energy densities of active and sterile neutrinos can be consistently embedded into the generalized Chaplygin gas (GCG), the unified dark sector model. In addition, dark matter adiabatically coupled to dark energy allows for a natural decoupling of the (active) mass varying neutrino (MaVaN) component from the dark sector. Thus MaVaN's turn into a secondary effect. Through the scale parameters, $\\xi$ and $s$, the proposed scenario allows for a convergence among three distinct frameworks: the {\\em cosmon} scenario, the {\\em seesaw} mechanism for mass generation and the GCG model. It is found that the equation of state of the perturbati...
Constraints on the generalized Chaplygin gas model from gamma-ray bursts
Energy Technology Data Exchange (ETDEWEB)
Freitas, Rodolfo Camargo; Goncalves, Sergio Vitorino de Borba; Velten, H.E.S. [Universidade Federal do Espirito Santo (UFES), ES (Brazil). Dept. de Fisica. Grupo de Gravitacao e Cosmologia
2011-07-01
Full text: One of the most important problems of Modern Cosmology is the determination of the matter content of the Universe. Combining data of the rotation curve of spiral galaxies, the dynamics of galaxy clusters and structure formation indicate that there is about ten times more pressureless matter in the Universe than can be afforded by the baryonic matter. Moreover, the Type Ia supernovae (SNe Ia) data indicates that the Universe is accelerating. Models considering matter content dominated by an exotic fluid whose pressure is negative is one of the proposals to explain this current accelerated phase of the Universe. At the same time, the position of the first acoustic peak in the spectrum of CMB anisotropies, as obtained by WMAP, favours a spatially flat Universe. If we consider the matter content of the Universe dominated by a fluid with negative pressure we have a scenario with a proportion of {Omega}{sub m} {approx} 0.27 and the {Omega}{sub de} {approx} 0.73, with respect to the critical density, for the fractions of the pressureless matter and dark energy, respectively. Much observational data that has been used for comparison with the theoretical cosmological models like the generalized Chaplygin gas model. The spectra of anisotropy of cosmic microwave background radiation, baryonic acoustic oscillations, the integrated Sachs-Wolfe effect, the matter power spectrum, gravitational lenses, X-ray data and ages estimates of high-z objects have been used in this sense. Gamma-ray bursts are jets that release {approx} 10{sup 51} - 10{sup 53} ergs or more for a few seconds and becomes, in this brief period of time, the most bright object in the Universe. The search for a self-consistent method to use the GRBs in cosmological problems is intense and promising. In a recent article Liang et al. employed a method to obtain the distance moduli {approx} of GRBs in the redshift range of SNe Ia and extend this result to very high redshift GRBs (z > 1.4) in a completely
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.)
Chaplygin-gas Solutions of f(R) Gravity
Elmardi, Maye; Solomons, Deon; Tekola, Abiy
2016-01-01
We explore exact f(R) gravity solutions that mimic Chaplygin-gas inspired LCDM cosmology. Starting with the original and modified Chaplygin gas equations of state, we reconstruct the forms of f(R) Lagrangians. The resulting solutions are generally quadratic in the Ricci scalar, but have appropriate LCDM solutions in limiting cases. These solutions, given appropriate initial conditions, can be potential candidates for scalar field-driven early universe expansion (inflation) and dark energy-driven late-time cosmic acceleration.
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.)
Cosmological Imprints of a Generalized Chaplygin Gas Model for the Early Universe
Energy Technology Data Exchange (ETDEWEB)
Bouhmadi-Lopez, Mariam; /Lisbon, CENTRA; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC; Liu, Yen-Wei; /Taiwan, Natl. Taiwan U.
2012-06-06
We propose a phenomenological model for the early universe where there is a smooth transition between an early quintessence phase and a radiation-dominated era. The matter content is modeled by an appropriately modified Chaplygin gas for the early universe. We constrain the model observationally by mapping the primordial power spectrum of the scalar perturbations to the latest data of WMAP7. We compute as well the spectrum of the primordial gravitational waves as would be measured today. We show that the high frequencies region of the spectrum depends on the free parameter of the model and most importantly this region of the spectrum can be within the reach of future gravitational waves detectors.
Shabani, Hamid
2016-01-01
In this paper, we investigate the cosmological consequences of a scenario for the recently reported accelerated expansion of the Universe, in which the generalized Chaplygin gas (GCG) and the baryonic matter are responsible for this observed phenomenon. Here, we have worked in an isotropic and homogeneous FLRW space time in $f(R,T)$ theory of gravity. We consider three classes of models which include three different forms of $f(R,T)$ function; Class $I$, are those models which employ the standard Chaplygin gas (SCG), in class $II$, we use GCG in the high pressure regime and finally, models $III$ make use of GCG in the high density regimes. The effective equation of state (EoS), the deceleration parameter for these models are calculated and showed that the related present values are more observationally acceptable in $f(R,T)$ gravity, compared to the corresponding ones in the General Relativity (GR). And, among them class $III$ have a better situation; the predictions of these models are more consistent with t...
Does Chaplygin gas have salvation?
Campos, Juliano Pereira; Perez, Rafael; Piattella, Oliver F; Velten, Hermano
2012-01-01
We investigate the unification scenario provided by the generalised Chaplygin gas model (a perfect fluid characterized by an equation of state p = -A/\\rho^{\\alpha}). Our concerns lie with a possible tension existing between background kinematic tests and those related to the evolution of small perturbations. We analyse data from the observation of the differential age of the universe, type Ia supernovae, baryon acoustic oscillations and the position of the first peak of the angular spectrum of the cosmic background radiation. We show that these tests favour negative values of the parameter \\alpha: we find \\alpha = -0.089^{+0.161}_{-0.128} at the 2\\sigma level. These would correspond to negative values of the square speed of sound which are unacceptable from the point of view of structure formation. We discuss a possible solution to this problem, when the generalised Chaplygin gas is framed in the modified theory of gravity proposed by Rastall. We show that a fluid description within this theory does not serve...
Viscous dissipative Chaplygin gas dominated homogenous and isotropic cosmological models
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...
Spherical thin-shell wormholes and modified Chaplygin gas
Energy Technology Data Exchange (ETDEWEB)
Sharif, M.; Azam, M., E-mail: msharif.math@pu.edu.pk, E-mail: azammath@gmail.com [Department of Mathematics, University of the Punjab, Quaid-e-Azam Campus, Lahore-54590 (Pakistan)
2013-05-01
The purpose of this paper is to construct spherical thin-shell wormhole solutions through cut and paste technique and investigate the stability of these solutions in the vicinity of modified Chaplygin gas. The Darmois-Israel formalism is used to formulate the stresses of the surface concentrating the exotic matter. We explore the stability of the wormhole solutions by using the standard potential method. We conclude that there exist more stable as well as unstable solutions than the previous study with generalized Chaplygin gas [19].
Crossing the Phantom divide line in the Chaplygin gas model
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.
Fitting the Supernova Type Ia Data with the Chaplygin Gas
Fabris, J C; De Souza, P E
2002-01-01
The supernova type Ia observational data are fitted using a model with cold dark matter and the Chaplygin gas. The Chaplygin gas, which is characterized by a negative pressure varying with the inverse of density, represents in this model the dark energy responsible for the accelaration of the universe. The fitting depends essentially on four parameters: the Hubble constant, the velocity of sound of the Chaplygin gas and the fraction density of the Chaplygin gas and the cold dark matter. The best fitting model is obtained with H_0 = 65 km/Mpc.s, $c_s^2 \\sim 0.92c$ and Omega_{c0} = 1, Omega_{m0} = 0, that is, a universe completely dominated by the Chaplygin gas. This reinforces the possibility that the Chaplygin gas may unify dark matter and dark energy, as it has already been claimed in the literature.
FRW Cosmology with the Extended Chaplygin Gas
Directory of Open Access Journals (Sweden)
B. Pourhassan
2014-01-01
Full Text Available We propose extended Chaplygin gas equation of state for which it recovers barotropic fluid with quadratic equation of state. We use numerical method to investigate the behavior of some cosmological parameters such as scale factor, Hubble expansion parameter, energy density, and deceleration parameter. We also discuss the resulting effective equation of state parameter. Using density perturbations we investigate the stability of the theory.
Viscous Chaplygin Gas Models as a Spherical Top-Hat Collapsing Fluids
Jawad, Abdul
2016-01-01
We study the spherical top-hat collapse in Einstein gravity and loop quantum cosmology by taking the non-linear evolution of viscous modified variable chaplygin gas and viscous generalized cosmic chaplygin gas. We calculate the equation of state parameter, square speed of sound, perturbed equation of state parameter, perturbed square speed of sound, density contrast and divergence of peculiar velocity in perturbed region and discussed their behavior. It is observed that both chaplygin gas models support the spherical collapse in Einstein as well as loop quantum cosmology because density contrast remains positive in both cases and the perturbed equation of state parameter remains positive at the present epoch as well as near future. It is remarked here that these parameters provide the consistence results for both chaplygin gas models in both gravities.
Variable modified Chaplygin gas in the holographic dark energy scenario
Chattopadhyay, Surajit; Debnath, Ujjal
2012-07-01
The holographic principle emerged in the context of black-holes, where it was noted that a local quantum field theory can not fully describe the black holes [1]. Some long standing debates regarding the time evolution of a system, where a black hole forms and then evaporates, played the key role in the development of the holographic principle [2,3,4]. The Chaplygin gas is characterized by an exotic equation of state p=-B/ρ. where B is a positive constant. Role of Chaplygin gas in the accelerated universe has been studied by several authors. The above mentioned equation of state has been modified to p=-B/ρ^{α}, where α lies between 0 and 1. This equation has been further modified to p=-A+B/ρ^{α}. This is called the modified Chaplygin gas. Debnath [5] introduced a variable modified Chaplygin gas by considering B as a function of scale factor a. In this work, we have considered that the universe is filled with normal matter and variable modified Chaplygin gas. Also we have considered the interaction between normal matter and variable modified Chaplygin gas in FRW universe. Then we have considered a correspondence between the holographic dark energy density and interacting variable modified Chaplygin gas energy density. Then we have reconstructed the potential of the scalar field which describes the variable modified Chaplygin cosmology References: [1] K. Enqvist, S. Hannested and M. S. Sloth, JCAP 2, 004 (2005). [2] L. Thorlocius, hep-th/0404098. [3] G. T. Hooft, gr-qc/9310026. [4] L. Susskind, J. Math. Phys. 36, 6377 (1995). [5] U. Debnath, Astrophys. Space Sci. 312, 295 (2007).
Inflationary cosmology with Chaplygin gas in Palatini formalism
Borowiec, Andrzej; Szydlowski, Marek; Wojnar, Aneta
2015-01-01
We present a simple generalisation of the $\\Lambda$CDM model which on the one hand reaches very good agreement with the present day experimental data and provides an internal inflationary mechanism on the other hand. It is based on Palatini modified gravity with quadratic Starobinsky term and generalized Chaplygin gas as a matter source providing, besides a current accelerated expansion, the epoch of endogenous inflation driven by type III freeze singularity. It follows from our statistical analysis that astronomical data favours negative value of the parameter coupling quadratic term into Einstein-Hilbert Lagrangian and as a consequence the bounce instead of initial Big-Bang singularity is preferred.
Constraints on modified Chaplygin gas from large scale structure
Paul, Bikash Chandra; Thakur, Prasenjit; Beesham, Aroon
2016-10-01
We study cosmological models with modified Chaplygin gas (MCG) to determine observational constraints on its EoS parameters using the background and the growth tests data. The background test data consists of H(z)-z data, Baryonic Acoustic Oscillations peak parameter, CMB shift parameter, SN Ia data and the growth test data consists of the linear growth function for the large scale structures of the universe are considered to study MCG in favor of dark energy. For a given range of redshift, the Wiggle-Z measurements and rms mass fluctuations from Ly-α data, employed for analyzing cosmological models numerically to constrain the MCG parameters. The Wang-Steinhardt ansatz for the growth index (γ ) and growth function (f) are also considered for numerical analysis. The best-fit values of EoS parameters determined here are used to study the variation of f, growth index (γ ), EoS parameter, squared sound speed and deceleration parameter with redshift. The constraints on the MCG parameters found here are compared with that of GCG (generalized Chaplygin gas) model for viable cosmology. Cosmologies with MCG satisfactorily describe late acceleration followed by a matter dominated phase. The range of values of EoS parameters, the associated parameters (f, γ , ω , Ω, c2s, q) are also determined from observational data in order to understand the suitability of the MCG model.
Dynamical Evolution of Modified Chaplygin Gas
Institute of Scientific and Technical Information of China (English)
FU Ming-Hui; WU Ya-Bo; HE Jing
2008-01-01
Based our previous work [Mod.Phys.Lett.A 22 (2007) 783,Gen.Relat.Grav.39 (2007) 653],some properties of modified Chaplygin gas (MCG) as a dark energy model continue to be studied mainly in two aspects: one is the change rates of the energy density and energy transfer,and the other is the evolution of the growth index.It is pointed that the density of dark energy undergoes the change from decrease to increase no matter whether the interaction between dark energy and dark matter exists or not,but the corresponding transformation points are different from each other.Furthermore,it is stressed that the MCG model even supports the existence of interaction between dark energy and dark matter,and the energy of transfer flows from dark energy to dark matter.The evolution of the interaction term with an ansatz 3Hc2p is discussed with the MCG model.Moreover,the evolution of the growth index f in the MCG model without interaction is illustrated,from which we find that the evolutionary trajectory of f overlaps with that of the ACDM model when α> 0.7 and its theoretical value f≈0.566 given by us at z=0.15 is consistent with the observations.
Spherical "Top-Hat" Collapse in a Modified Chaplygin Gas Dominated Universe
Karbasi, S
2015-01-01
Considering perturbation growth in spherical Top-Hat model of structure formation in a generalized Chaplygin gas dominated universe, we want to study this scenario with modified Chaplygin gas model. Different parameters of this scenario for positive and negative values of A are computed. The evolution of background and collapsed region parameters are found for different cases. The stability of the model and the collapse time rate are considered in different cases. The turn-around redshifts for different values of alpha are computed; the results are in relatively good agreement with current observational data.
Extended Chaplygin Gas in Horava-Lifshitz Gravity
Pourhassan, B
2014-01-01
In this paper, we investigate cosmological models of the extended Chaplygin gas in a universe governed by Horava-Lifshitz gravity. The equation of state for an extended Chaplygin gas is a (n+2)-variable equation determined by A_{n}, alpha, and B. In this work, we are interested to the case of second order (n=2) equation of state which recovers quadratic barotropic equation of state. In that case there are four free parameters. Under some assumptions we relate free parameters to each other to have only one free independent parameter (A_{2}). It help us to obtain explicit expression for energy density in terms of scale factor. The allowed values of the second order extended Chaplygin gas parameter is determined using the recent astrophysical and cosmological observational data.
Extended Chaplygin gas in Horava-Lifshitz gravity
Pourhassan, B.
2016-09-01
In this paper, we investigate cosmological models of the extended Chaplygin gas in a universe governed by Horava-Lifshitz gravity. The equation of state for an extended Chaplygin gas is a (n + 2) -variable equation determined by An, α, and B. In this work, we are interested to the case of second order (n = 2) equation of state which recovers quadratic barotropic equation of state. In that case there are four free parameters. We solve conservation equation approximately and obtain energy density in terms of scale factor with mentioned free parameters. Under some assumptions we relate free parameters to each other to have only one free independent parameter (A2) . It help us to obtain explicit expression for energy density in terms of scale factor. The allowed values of the second order extended Chaplygin gas parameter is fixed using the recent astrophysical and cosmological observational data. Thermodynamics of the model investigated based on the first and second law of thermodynamics.
Thin-shell wormholes in Born–Infeld electrodynamics with modified Chaplygin gas
Energy Technology Data Exchange (ETDEWEB)
Sharif, M., E-mail: msharif.math@pu.edu.pk [Department of Mathematics, University of the Punjab, Quaid-e-Azam Campus, Lahore-54590 (Pakistan); Azam, M., E-mail: azam.math@ue.edu.pk [Department of Mathematics, University of the Punjab, Quaid-e-Azam Campus, Lahore-54590 (Pakistan); Division of Science and Technology, University of Education, Township Campus, Lahore-54590 (Pakistan)
2014-07-25
In this paper, we construct spherically symmetric thin-shell wormholes in the scenario of Born–Infeld electrodynamics theory. We take the modified Chaplygin gas for the description of exotic matter around the wormhole throat. The stability of static wormhole solutions with different values of charge and Born–Infeld parameter is investigated. We compare our results with those obtained for generalized Chaplygin gas [36] and conclude that stable static wormhole solutions also exist even for large value of Born–Infeld parameter. - Highlights: • Constructed thin-shell wormholes in Born–Infeld electrodynamics for modified Chaplygin. • Studied its stability with different values of charge and Born–Infeld parameter. • New stable solutions are found even for large value of Born–Infeld parameter. • Selection of EoS significantly changes the presence and stability of static solutions.
Theoretical construction of wormholes supported by Chaplygin gas
Kuhfittig, Peter K F
2008-01-01
The purpose of this paper is to examine the possible existence or construction of traversable wormholes supported by generalized Chaplygin gas (GCG) by starting with a general line element and the Einstein tensor, together with the equation of state, thereby continuing an earlier study by the author of wormholes supported by phantom energy. Numerical techniques are used to demonstrate the existence of wormhole spacetimes that (1) meet the flare-out conditions at the throat, (2) are traversable by humanoid travelers, thanks to low tidal forces and short proper distances near the throat, and (3) are asymptotically flat. There appears to be an abundance of solutions that avoid an event horizon, suggesting the possibility of naturally occurring wormholes. A final topic considered briefly is the case of an isotropic pressure.
Constraints on gen4eralized Chaplygin gas model including gamma-ray bursts
Institute of Scientific and Technical Information of China (English)
Fa-Yin Wang; Zi-Gao Dai; Shi Qi
2009-01-01
Generalized Chaplygin gas (whose equation of state is PGCG = -A/PGCGα) was proposed as a candidate for unification of dark energy and dark matter. We inves-tigate constraints on this model with the latest observed data. We test the model with type-Ia supernovae (SNe Ia), cosmic microwave background (CMB) anisotropy, X-ray gas mass fractions in clusters, and gamma-ray bursts (GRBs). We calibrate the GRB lu-minosity relations without assuming any cosmological models using SNe Ia. We show that GRBs can extend the Hubble diagram to higher redshifts (z> 6). The GRB Hubble diagram is well behaved and delineates the shape of the Hubble diagram well. We mea-sure As≡A/PGCG,0α+1=0.68-0.08+0.04 (where PGCG,0 is the energy density today) and α=-0.22-0.13+0.15at the 1σconfidence level using all the datasets. Our results rule out the standard Chaplygin gas model (α = 1) at the 3a confidence level. The ACDM is allowed at the 2or confidence level. We find that acceleration could have started at a redshift of z ～ 0.70. The concordance of the generalized Chaplygin gas model with the age estimate of an old high redshift quasar is found. In addition, we show that GRBs can break the degeneracy between the generalized Chaplygin gas model and the XCDM model.
Interacting $F(R,T)$ gravity with modified Chaplygin gas
Amani, Ali R
2014-01-01
In this paper, we have studied $F(R,T)$ gravity as an arbitrary function of curvature and torsion scalars in Friedmann--Lema\\^{\\i}tre--Robertson--Walker (FLRW) background. Then, we have considered interacting model between $F(R,T)$ gravity and modified Chaplygin gas. The novelty of this model is that the Universe includes both cases curvature and torsion, and one dominated by a Chaplygin gas. In order to calculate cosmological solutions, we obtained Friedmann equations and also equation of state (EoS) parameter of dark energy. By employing interacting model we considered the total energy density and the total pressure of Universe as the combination of components of dark energy and Chaplygin gas. Subsequently, we reconstructed the model by an origin of a scalar field entitled quintessence model with a field potential. The field potential has been calculated in terms of free parameters of $F(R,T)$ gravity and modified Chaplygin gas. In what follows, we used a parametrization, and the cosmological parameters hav...
Concentration in vanishing pressure limit of solutions to the modified Chaplygin gas equations
Yang, Hanchun; Wang, Jinhuan
2016-11-01
Two kinds of occurrence mechanism on the phenomenon of concentration and the formation of delta shock wave in vanishing pressure limit of solutions to the modified Chaplygin gas equations are analyzed and identified. The Riemann problem of the modified Chaplygin gas equations is first solved. Then it is shown that, as the pressure vanishes, any two-shock Riemann solution tends to a delta-shock solution to the transport equations, and the intermediate density between the two shocks tends to a weighted δ-measure which forms a delta shock wave; any two-rarefaction-wave Riemann solution tends to a two-contact-discontinuity solution to the transport equations, and the nonvacuum intermediate state in between tends to a vacuum state. It is also shown that, as the pressure approaches the generalized Chaplygin gas pressure, any two-shock Riemann solution tends to a delta-shock solution to the generalized Chaplygin gas equations. Some numerical results are presented to show the formation process of delta shock waves and vacuum states.
Modified Chaplygin Gas with Variable G and A
Institute of Scientific and Technical Information of China (English)
Ujjal Debnath
2011-01-01
We consider a modified Chaplygin gas with the gravitational constant G and the cosmological constant A.The trivial solution describes decelerating phase to accelerating phase of the universe.The non-static with constant equation of state describes the inflationary solution.For static universe,G and A must be formed arbitrarily,and for static universe with constant equation of state,G and A should be constant.The Einstein field equation has two parameters,i.e.the gravitational constant G and the cosmological constant A.The Newtonian constant of gravitation G plays the role of a coupling constant between geometry and matter in the Einstein field equations.In an evolving Universe,it appears natural to look at this "constant" as a function of time.Numerous suggestions based on different arguments have been proposed in the past few decades in which G varies with time.[1,2] Dirac[3-6] proposed a theory with variable G motivated by the occurrence of large numbers discovered by Weyl,Eddington and Dirac himself.Many other extensions of Einstein's theory with time-dependent G have also been proposed to achieve a possible unification of gravitation and elementary particle physics or to incorporate Mach's principle in general relativity.[7-9]%We consider a modified Chaplygin gas with the gravitational constant G and the cosmological constant A. The trivial solution describes decelerating phase to accelerating phase of the universe. The non-static with constant equation of state describes the inflationary soiution. For static universe, G and A must be formed arbitrarily, and for static universe with constant equation of state, G and A should be constant.
Generalized Chaplygin cosmology with changeable-signs interactions
Directory of Open Access Journals (Sweden)
XI Ping
2013-06-01
Full Text Available Using phase space analysis methods,we discuss two kinds of Generalized Chaplygin cosmology with changeable-signs interactions dynamically.Some new stable attractor solutions and heteroclinic trajectory solutions are found in these two types of models.
Late time attractors of some varying Chaplygin gas cosmological models
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.
Wormholes supported by phantom-like modified Chaplygin gas
Rashid, Muneer Ahmad; Farooq, Umar
2008-01-01
We have examined the possible construction of a stationary, spherically symmetric and spatially inhomogeneous wormhole spacetime supported by the phantom energy. The later is supposed to be represented by the modified Chaplygin gas equation of state. The solutions so obtained satisfy the flare out and the asymptotic flatness conditions. It is also shown that the averaged null energy condition has to be violated for the existence of the wormhole.
FRW Bulk Viscous Cosmology with Modified Chaplygin Gas in Flat Space
Saadat, H
2016-01-01
In this paper we study FRW bulk viscous cosmology in presence of modified Chaplygin gas. We write modified Friedmann equations due to bulk viscosity and Chaplygin gas and obtain time-dependent energy density for the special case of flat space.
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.
Chaplygin gas inspired scalar fields inflation via well-known potentials
Jawad, Abdul; Butt, Sadaf; Rani, Shamaila
2016-08-01
Brane inflationary universe models in the context of modified Chaplygin gas and generalized cosmic Chaplygin gas are being studied. We develop these models in view of standard scalar and tachyon fields. In both models, the implemented inflationary parameters such as scalar and tensor power spectra, scalar spectral index and tensor to scalar ratio are derived under slow roll approximations. We also use chaotic and exponential potential in high energy limits and discuss the characteristics of inflationary parameters for both potentials. These models are compatible with recent astronomical observations provided by WMAP7{+}9 and Planck data, i.e., ηs=1.027±0.051, 1.009±0.049, 0.096±0.025 and r<0.38, 0.36, 0.11.
Chaplygin gas Hořava-Lifshitz quantum cosmology
Ardehali, Hossein; Pedram, Pouria
2016-02-01
In this paper, we study the Chaplygin gas Hořava-Lifshitz quantum cosmology. Using Schutz formalism and Arnowitt-Deser-Misner decomposition, we obtain the corresponding Schrödinger-Wheeler-DeWitt equation. We obtain exact classical and quantum mechanical solutions and construct wave packets to study the time evolution of the expectation value of the scale factor for two cases. We show that unlike classical solutions and upon choosing appropriate initial conditions, the expectation value of the scale factor never tends to the singular point which exhibits the singularity-free behavior of the solutions in the quantum domain.
Cosmic walls and filaments formation in modified Chaplygin gas cosmology
Karbasi, S
2016-01-01
We want to study the perturbation growth of an initial seed of an ellipsoidal shape in Top-Hat collapse model of structure formation in the Modified Chaplygin gas cosmology. Considering reasonable values of the constants and the parameters of the model under study, it is shown that a very small deviation from spherical symmetry (ellipsoidal geometry) in the initial seed leads to a final highly non-spherical structure which can be considered as a candidate for justifying already known cosmological structures as cosmic walls and filaments.
Unified universe history through phantom extended Chaplygin gas
Pourhassan, B
2015-01-01
We investigate the universe evolution from inflation to late-time acceleration in a unified way, using a two-component fluid constituted from extended Chaplygin gas alongside a phantom scalar field. We extract solutions for the various cosmological eras, focusing on the behavior of the scale factor, the various density parameters and the equation-of-state parameter. Furthermore, we extract and discuss bouncing solutions. Finally, we examine the perturbations of the model, ensuring about their stability and extracting the predictions for the tensor-to-scalar ratio.
Chaplygin Gas Ho\\v{r}ava-Lifshitz Quantum Cosmology
Ardehali, Hossein
2016-01-01
In this paper, we study the Chaplygin gas Ho\\v{r}ava-Lifshitz quantum cosmology. Using Schutz formalism and Arnowitt-Deser-Misner decomposition, we obtain the corresponding Schr\\"{o}dinger-Wheeler-DeWitt equation. We obtain exact classical and quantum mechanical solutions and construct wave packets to study the time evolution of the expectation value of the scale factor for two cases. We show that unlike classical solutions and upon choosing appropriate initial conditions, the expectation value of the scale factor never tends to the singular point which exhibits the singularity-free behavior of the solutions in the quantum domain.
Mass Power Spectrum in a Universe Dominated by the Chaplygin Gas
Fabris, J C
2002-01-01
The mass power spectrum for a Universe dominated by the Chaplygin gas is evaluated numerically from scales of the order of the Hubble horizon to 100 Mpc. The results are compared with a pure baryonic Universe and a cosmological constant model. In all three cases, the spectrum increases with k, the wavenumber of the perturbations. The slope of the spectrum is higher for the baryonic model and smaller for the cosmological constant model, the Chaplygin gas interpolating these two models. The results are analyzed in terms of the sound velocity of the Chaplygin gas and the moment the Universe begins to accelerate.
Interacting Viscous Modified Chaplygin Gas Cosmology in Presence of Cosmological Constant
Karimiyan, K.; Naji, J.
2014-07-01
Here, we consider interacting viscous modified Chaplygin gas in presence of cosmological constant. We assumed bulk viscosity as a function of density. We consider interaction between modified Chaplygin gas and baryonic matter. Then, the effects of viscosities on the cosmological parameters such as energy, density, Hubble expansion parameter, scale factor and deceleration parameter investigated. This model may be considered as a toy model of our universe.
Viability of variable generalised Chaplygin gas: a thermodynamical approach
Panigrahi, D.; Chatterjee, S.
2017-03-01
The viability of the variable generalised Chaplygin gas (VGCG) model is analysed from the standpoint of its thermodynamical stability criteria with the help of an equation of state, P = - B/ρ ^{α }, where B = B0V^{-n/3}. Here B0 is assumed to be a positive universal constant, n is a constant parameter and V is the volume of the cosmic fluid. We get the interesting result that if the well-known stability conditions of a fluid is adhered to, the values of n are constrained to be negative definite to make ( partial P/partial V) S caloric equation of state parameter when T → 0. It may also be mentioned that like Santos et al. our model does not admit of any critical points. We also observe that although the earlier model of Lu explains many of the current observational findings of different probes it fails to explain the crucial tests of thermodynamical stability.
First cosmological constraints on the Superfluid Chaplygin gas model
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: $z_t$.
Modified Chaplygin gas inspired inflationary model in braneworld scenario
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.
Oblique derivative problem for general Chaplygin-Rassias equations
Institute of Scientific and Technical Information of China (English)
2008-01-01
The present paper deals with the oblique derivative problem for general second order equations of mixed （elliptic-hyperbolic） type with the nonsmooth parabolic degenerate line K1（y）uxx+|K2（x）|uyy+a（x,y）ux+b（x, y）uy+c（x,y）u=-d（x,y） in any plane domain D with the boundary D=Γ∪L1∪L2∪L3∪L4, whereΓ（■{y>0}）∈Cμ2 （0<μ<1） is a curve with the end points z=-1,1. L1, L2, L3, L4 are four characteristics with the slopes -H2（x）/H1（y）, H2（x）/H1（y）,-H2（x）/H1（y）, H2（x）/H1（y）(H1（y）=|k1（y）|1/2, H2（x）=|K2（x）|1/2 in {y<0}) passing through the points z=x+iy=-1,0,0,1 respectively. And the boundary condition possesses the form 1/2 u/v=1/H（x,y）Re[λuz]=r（z）, z∈Γ∪L1∪L4, Im[λ（z）uz]|z=zl=bl, l=1,2, u（-1）=b0, u（1）=b3, in which z1, z2 are the intersection points of L1, L2, L3, L4 respectively. The above equations can be called the general Chaplygin-Rassias equations, which include the Chaplygin-Rassias equations K1（y）（M2（x）ux）x+M1（x）（K2（y）uy）y+r（x,y）u=f（x,y）, in D as their special case. The above boundary value problem includes the Tricomi problem of the Chaplygin equation: K（y）uxx+uyy=0 with the boundary condition u（z）=φ（z） onΓ∪L1∪L4 as a special case. Firstly some estimates and the existence of solutions of the corresponding boundary value problems for the degenerate elliptic and hyperbolic equations of second order are discussed. Secondly, the solvability of the Tricomi problem, the oblique derivative problem and Frankl problem for the general Chaplygin- Rassias equations are proved. The used method in this paper is different from those in other papers, because the new notations W（z）=W（x+iy）=uz=[H1（y）ux-iH2（x）uy]/2 in the elliptic domain and W（z）=W（x+jy）=uz=[H1（y）ux-jH2（x）uy]/2 in the hyperbolic domain are introduced for the first time, such that the second order equations of
Modified Chaplygin gas as an interacting holographic dark energy model
Institute of Scientific and Technical Information of China (English)
无
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.
Viability of Variable Generalised Chaplygin gas - a thermodynamical approach
Panigrahi, D
2016-01-01
The viability of the variable generalised Chaplygin gas (VGCG) model is analysed from the standpoint of its thermodynamical stability criteria with the help of an equation of state, $P = - \\frac{B}{\\rho^{\\alpha}}$, where $B = B_{0}V^{-\\frac{n}{3}}$. Here $B_{0}$ is assumed to be a positive universal constant, $n$ is a constant parameter and $V$ is the volume of the cosmic fluid. We get the interesting result that if the well-known stability conditions of a fluid is adhered to, the values of $n$ are constrained to be negative definite to make $ \\left(\\frac{\\partial P}{\\partial V}\\right)_{S} <0$ \\& $ \\left(\\frac{\\partial P}{\\partial V}\\right)_{T} <0$ throughout the evolution. Moreover the positivity of thermal capacity at constant volume $c_{V}$ as also the validity of the third law of thermodynamics are ensured in this case. For the particular case $n = 0$ the effective equation of state reduces to $\\Lambda$CDM model in the late stage of the universe while for $n <0$ it mimics a phantom-like cosmo...
Observational constraints on Modified Chaplygin Gas from Large Scale Structure
Paul, Bikash Chandra; Beesham, Aroonkumar
2014-01-01
We study cosmological models with modified Chaplygin gas (in short, MCG) to determine observational constraints on its EoS parameters. The observational data of the background and the growth tests are employed. The background test data namely, H(z)-z data, CMB shift parameter, Baryonic acoustic oscillations (BAO) peak parameter, SN Ia data are considered to study the dynamical aspects of the universe. The growth test data we employ here consists of the linear growth function for the large scale structures of the universe, models are explored assuming MCG as a candidate for dark energy. Considering the observational growth data for a given range of redshift from the Wiggle-Z measurements and rms mass fluctuations from Ly-$\\alpha$ measurements, cosmological models are analyzed numerically to determine constraints on the MCG parameters. In this case, the Wang-Steinhardt ansatz for the growth index $\\gamma$ and growth function $f$ (defined as $f=\\Omega_{m}^{\\gamma} (a)$) are also taken into account for the numeri...
Chaplygin Gas of Tachyon Nature Imposed by Symmetry and Constrained via H(z) Data
Collodel, Lucas Gardai
2015-01-01
An action of general form is proposed for a Universe containing matter, radiation and dark energy. The latter is interpreted as a tachyon field non-minimally coupled to the scalar curvature. The Palatini approach is used when varying the action so the connection is given by a more generic form. Both the self-interaction potential and the non-minimally coupling function are obtained by constraining the system to present invariability under global point transformation of the fields (Noether Symmetry). The only possible solution is shown to be that of minimal coupling and constant potential (Chaplygin gas). The behavior of the dynamical properties of the system is compared to recent observational data, which infers that the tachyon field must indeed be dynamical.
Chaplygin gas of Tachyon Nature Imposed by Noether Symmetry and constrained via H(z) data
Gardai Collodel, Lucas; Medeiros Kremer, Gilberto
2016-04-01
An action of general form is proposed for a Universe containing matter, radiation and dark energy. The latter is interpreted as a tachyon field non-minimally coupled to the scalar curvature. The Palatini approach is used when varying the action so the connection is given by a more generic form. Both the self-interaction potential and the non-minimally coupling function are obtained by constraining the system to present invariability under global point transformation of the fields (Noether Symmetry). The only possible solution is shown to be that of minimal coupling and constant potential (Chaplygin gas). The behavior of the dynamical properties of the system is compared to recent observational data, which infers that the tachyon field must indeed be dynamical.
Irreversible Processes in a Universe modelled as a mixture of a Chaplygin gas and radiation
Kremer, G M
2003-01-01
The evolution of a Universe modelled as a mixture of a Chaplygin gas and radiation is determined by taking into account irreversible processes. This mixture could interpolate periods of a radiation dominated, a matter dominated and a cosmological constant dominated Universe. The results of a Universe modelled by this mixture are compared with the results of a mixture whose constituents are radiation and quintessence. Among other results it is shown that: (a) for both models there exists a period of a past deceleration with a present acceleration; (b) the slope of the acceleration of the Universe modelled as a mixture of a Chaplygin gas with radiation is more pronounced than that modelled as a mixture of quintessence and radiation; (c) the energy density of the Chaplygin gas tends to a constant value at earlier times than the energy density of quintessence does; (d) the energy density of radiation for both mixtures coincide and decay more rapidly than the energy densities of the Chaplygin gas and of quintessen...
Extended Chaplygin gas equation of state with bulk and shear viscosities
Naji, Jalil
2014-03-01
In this note extended Chaplygin gas equation of state includes bulk and shear viscosities suggested. Bulk viscosity assumed as power law form of density and shear viscosity considered as a constant. We study evolution of dark energy density numerically for several forms of scale factor, and analytically under some assumptions corresponding to early universe. We found our model is stable for infinitesimal viscous parameters.
Viscous New Varying Modified Cosmic Chaplygin Gas with Cosmological Constant in Non-flat Universe
Naji, Jalil; Saadat, Hassan
2014-05-01
In this paper we study new varying modified cosmic Chaplygin gas which has viscosity in presence of cosmological constant and space curvature. By using well-known forms of scale factor in Friedmann equation we obtain behavior of dark energy density numerically. We use observational data to fix solution and discuss about stability of our system.
Effect of Shear and Bulk Viscosities on Interacting Modified Chaplygin Gas Cosmology
Naji, J.; Pourhassan, B.; Amani, Ali R.
2014-12-01
In this paper, we study interacting modified Chaplygin gas (MCG) which has shear and bulk viscosities. We consider sign-changeable interaction between MCG and matter, then investigate the effects of shear and bulk viscosities on the cosmological parameters such as energy, density, Hubble expansion parameter, scale factor and deceleration parameter.
Lu, Jianbo; Xu, Lixin; Wu, Yabo; Liu, Molin
2011-01-01
We use the Markov Chain Monte Carlo method to investigate a global constraints on the modified Chaplygin gas (MCG) model as the unification of dark matter and dark energy from the latest observational data: the Union2 dataset of type supernovae Ia (SNIa), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the cosmic microwave background (CMB) data. In a flat universe, the constraint results for MCG model are, $\\Omega_{b}h^{2}=0...
Open static Chaplygin universe
Khalatnikov, I M
2003-01-01
We apply the qualitative theory of dynamical systems to the study of the Chaplygin gas cosmological model. In difference to earlier works devoted to this model we give up sign restrictions on the choice of the sign of the energy density and on the parameters characterising initial conditions for a cosmological evolution. It appears that exists a static stable open universe filled with the Chaplygin gas. Besides exist universes where the acoustic waves have a velocity exceeding that of light in the vacuum.
Cosmic Microwave Background Radiation Constraints on a Modified Chaplygin Gas Model
Institute of Scientific and Technical Information of China (English)
LIU Dao-Jun; LI Xin-Zhou
2005-01-01
@@ A modified Chaplygin gas model of unifying dark energy and dark matter with the exotic equation of state p = Bρ- A/ρα , which can also explain the recent expansion of the universe, is investigated by means of constraining the location of the peak of the cosmic microwave background radiation spectrum. We find that the result of CMBR measurements does not exclude the nonzero value of parameter B, but allows it in the range -0.35 (＜～) B (＜～) 0.025.
Evolution of Holographic Dark Energy in Interacting Modified Chaplygin Gas Model
Institute of Scientific and Technical Information of China (English)
WANG Cong; WU Ya-Bo; LIU Fei
2009-01-01
We investigate the modified Chaplygin gas (MCG) with interaction between holographic dark energy proposed byb Li and dark matter. In this model, evolution of the universe is described in detail, which is from deceleration to acceleration. Specifically, the evolutions of related cosmological quantities such as density parameter, the equation of state of holographic dark energy, deceleration parameter and transition redshift are discussed. Moreover, we also give their present values which are consistent with the lately observations. Furthermore, the results given by us show such a model can accommodate a transition of the dark energy from a normal state wx > -1 to wx < -1 phantom regimes.
Analysis to the entangled states from an extended Chaplygin gas model
Meng, X H; Ren, J; Meng, Xin He; Hu, Ming Guang; Ren, Jie
2006-01-01
With considerations of the recently released WMAP year three and supernova legacy survey (SNLS) data set analysis that favors models similar to the $% \\Lambda CDM$ model by possibly mild fluctuations around the vacuum energy or the cosmological constant, we extend the original Chaplygin Gas model (ECG) via modifying the Chaplygin Gas equation of state by two parameters to describe an entangled mixture state from an available matter and the rest component (which can take the cosmological constant or dark energy as in the current cosmic stage, or `curvature-like' term, or radiation component in the early epoch, as various phases) coexistence. At low redshifts, the connection of the ECG model and the Born-infeld field is set up. As paradigms, we use the data coming from the recently released SNLS for the first year and also the famous 157 type Ia supernova (Ia SNe) gold dataset to constrain the model parameters. The restricted results demonstrate clearly how large the entangled degree or the ratio between the en...
Co-Existence of Modified Chaplygin Gas and Other Dark Energies in the Framework of Fractal Universe
Maity, Sayani; Debnath, Ujjal
2016-05-01
In this work, we consider a non-flat universe in the framework of fractal cosmology. We have investigated the co-existence of different kinds of dark energy models such as tachyonic field, DBI-essence, hessence, k-essence, dilaton, quintessence with the modified Chaplygin gas (MCG) in fractal universe and obtained the statefinder parameters. The natures of the scalar fields and the concerned potentials have been analyzed by the correspondence scenario in the fractal universe.
Observational constraints on modified Chaplygin gas in Horava–Lifshitz gravity with dark radiation
Indian Academy of Sciences (India)
B C Paul; P Thakur; M M Verma
2013-10-01
Cosmological models with modified Chaplygin gas (MCG) in the framework of Horava–Lifshitz (HL) theory of gravity, both with and without detailed balance, are obtained. The equation of state (EOS) for a MCG contains three unknown parameters namely, , , . The allowed values of some of these parameters of the EOS are determined using the recent astrophysical and cosmological observational data. Using observational data from $H(z)-z$, baryon acoustic oscillation (BAO) peak parameter and cosmic microwave background (CMB) shift parameter we study cosmologies in detailed-balance and beyond detailed-balance scenario. In this paper we take up the beyond detailed-balance scenario in totality and contribution of dark radiation in detailedbalance scenario on the parameters of the EOS. We explore the effect of dark radiation on the whole range of the effective neutrino parameter ($ N_{}$) to constrain matter contributing parameter in both the detailed-balance and the beyond detailed-balance scenarios. It has been observed that greater the dark radiation less the matter contribution in the MCG in both the scenario considered here. In order to check the validity of beyond detailed-balance scenario we plot supernovae magnitudes () with red-shift of Union2 data and then the variation of state parameter with redshift is studied. It is noted that beyond detailed-balance scenario is suitable for cosmological model in HL gravity with MCG.
Duality extended Chaplygin cosmologies with a big rip
Chimento, L P; Chimento, Luis P.; Lazkoz, Ruth
2006-01-01
We consider modifications to the Friedmann equation motivated by recent proposals along these lines pursuing an explanation to the observed late time acceleration. Here we show those modifications can be framed within a theory with self-interacting gravity, where the term self-interaction refers here to the presence of functions of $\\rho$ and $p$ in the right hand side of the Einstein equations. We then discuss the construction of the duals of the cosmologies generated within that framework. After that we investigate the modifications required to generate generalized and modified Chaplygin cosmologies and show that their duals belong to a larger family of cosmologies we call extended Chaplygin cosmologies. Finally, by letting the parameters of those models take values not earlier considered in the literature we show some representatives of that family of cosmologies display sudden future singularities, which indicates their behavior is rather different from generalized or modified Chaplygin gas cosmologies. T...
Duality gives rise to Chaplygin cosmologies with a big rip
Chimento, Luis P.; Lazkoz, Ruth
2006-05-01
We consider modifications to the Friedmann equation motivated by recent proposals along these lines pursuing an explanation to the observed late time acceleration. Here we show that these approaches can be framed within a theory with modified gravity, and we discuss the construction of the duals of the cosmologies generated within that framework. We then investigate the modifications required to generate extended, generalized and modified Chaplygin cosmologies, and then show that their duals belong to a larger family of cosmologies we call enlarged Chaplygin cosmologies. Finally, by letting the parameters of these models take values not earlier considered in the literature we show that some representatives of that family of cosmologies display sudden future singularities. This fact indicates that the behaviour of these spacetimes is rather different from that of generalized or modified Chaplygin gas cosmologies. This reinforces the idea that modifications of gravity can be responsible for unexpected evolutionary features in the universe.
Ranjit, Chayan
2015-01-01
FRW universe in Horava-Lifshitz (HL) gravity model filled with a combination of dark matter and dark energy in the form of variable modified Chaplygin gas (VMCG) is considered. The permitted values of the VMCG parameters are determined by the recent astrophysical and cosmological observational data. Here we present the Hubble parameter in terms of the observable parameters $\\Omega_{dm0}$, $\\Omega_{vmcg0}$, $H_{0}$, redshift $z$ and other parameters like $\\alpha$, $A$, $\\gamma$ and $n$. From Stern data set (12 points), we have obtained the bounds of the arbitrary parameters by minimizing the $\\chi^{2}$ test. The best-fit values of the parameters are obtained by 66\\%, 90\\% and 99\\% confidence levels. Next due to joint analysis with BAO and CMB observations, we have also obtained the bounds of the parameters ($A,\\gamma$) by fixing some other parameters $\\alpha$ and $n$. The best fit value of distance modulus $\\mu(z)$ is obtained for the VMCG model in HL gravity, and it is concluded that our model is perfectly co...
Chattopadhyay, Surajit
2017-03-01
This article reports a study on variable-generalised Chaplygin gas (VGCG) interacting with pressureless dark matter (DM) with interaction term Q chosen in the form Q=3HδρΛ, where ρΛ denotes the density of the VGCG. Detailed cosmology of the interacting VGCG has been studied and a quintom behaviour of the equation of state (EoS) parameter has been observed. A statefinder analysis has shown attainment of ΛCDM fixed point by the interacting VGCG. Subsequently, a reconstruction scheme for f(T) gravity has been presented based on the interacting VGCG with power-law form of scale factor. The EoS parameter corresponding to the reconstructed f(T) has shown quintom behaviour. Finally, we have studied the generalised second law (GSL) of thermodynamics in reconstructed f(T) cosmology considering the universe as a closed bounded system with future event horizon as the cosmological boundary. We have associated two different entropies with the cosmological horizons with a logarithmic correction term and a power-law correction term. We have studied the validity of the GSL for both of these corrections.
Rudra, Prabir; Kundu, Sujata
2013-01-01
Motivated by some previous works of Rudra et al we set to explore the background dynamics when dark energy in the form of New Variable Modified Chaplygin gas is coupled to dark matter with a suitable interaction in the universe described by brane cosmology. The main idea is to find out the efficiency of New variable modified Chaplygin gas to play the role of DE. As a result we resort to the technique of comparison with standard dark energy models. Here the RSII brane model have been considered as the gravity theory. An interacting model is considered in order to search for a possible solution of the cosmic coincidence problem. A dynamical system analysis is performed because of the high complexity of the system . The statefinder parameters are also calculated to classify the dark energy model. Graphs and phase diagrams are drawn to study the variations of these parameters and get an insight into the effectiveness of the dark energy model. It is also seen that the background dynamics of New Variable Modified C...
Shear and rotation in Chaplygin cosmology
Del Popolo, A; Maydanyuk, S P; Lima, J A S; Jesus, J F; 10.1103/PhysRevD.87.043527
2013-01-01
We study the effect of shear and rotation on results previously obtained dealing with the application of the spherical collapse model (SCM) to generalized Chaplygin gas (gCg) dominated universes. The system is composed of baryons and gCg and the collapse is studied for different values of the parameter $\\alpha$ of the gCg. We show that the joint effect of shear and rotation is that of slowing down the collapse with respect to the simple SCM. This result is of utmost importance for the so-called unified dark matter models, since the described slow down in the growth of density perturbation can solve one of the main problems of the quoted models, namely the instability described in previous papers [e.g., H. B. Sandvik {\\it et al.}, Phys. Rev. D {\\bf 69}, 123524 (2004)] at the linear perturbation level.
Constraining the Generalized and Superfluid Chaplygin Gas Models with the Sandage-Loeb Test
Zhu, Wen-Tao; Wu, Pu-Xun; Yu, Hong-Wei
2015-05-01
Not Available Supported by the National Natural Science Foundation of China under Grants Nos 11175093, 11222545, 11435006, and 11375092, the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20124306110001, and the K.C. Wong Magna Fund of Ningbo University.
A Discretization of the Nonholonomic Chaplygin Sphere Problem
Directory of Open Access Journals (Sweden)
Yuri N. Fedorov
2007-03-01
Full Text Available The celebrated problem of a non-homogeneous sphere rolling over a horizontal plane was proved to be integrable and was reduced to quadratures by Chaplygin. Applying the formalism of variational integrators (discrete Lagrangian systems with nonholonomic constraints and introducing suitable discrete constraints, we construct a discretization of the n-dimensional generalization of the Chaplygin sphere problem, which preserves the same first integrals as the continuous model, except the energy. We then study the discretization of the classical 3-dimensional problem for a class of special initial conditions, when an analog of the energy integral does exist and the corresponding map is given by an addition law on elliptic curves. The existence of the invariant measure in this case is also discussed.
Indian Academy of Sciences (India)
R CHAUBEY; A K SHUKLA; RAKESH RAUSHAN
2017-04-01
The general class of Bianchi cosmological models with dark energy in the form of modified Chaplygin gas with variable $\\Lambda$ and $G$ and bulk viscosity have been considered. We discuss three types of average scalefactor by using a special law for deceleration parameter which is linear in time with negative slope. The exact solutions to the corresponding field equations are obtained. We obtain the solution of bulk viscosity ($\\xi$ ), cosmologicalconstant ($\\Lambda$), gravitational parameter ($G$) and deceleration parameter ($q$) for different equations of state. The model describes an accelerating Universe for large value of time $t$ , wherein the effective negative pressure induced by Chaplygin gas and bulk viscous pressure are driving the acceleration.
Chaubey, R.; Shukla, A. K.; Raushan, Rakesh
2017-04-01
The general class of Bianchi cosmological models with dark energy in the form of modified Chaplygin gas with variable Λ and G and bulk viscosity have been considered. We discuss three types of average scale factor by using a special law for deceleration parameter which is linear in time with negative slope. The exact solutions to the corresponding field equations are obtained. We obtain the solution of bulk viscosity ( ξ), cosmological constant (Λ), gravitational parameter ( G) and deceleration parameter ( q) for different equations of state. The model describes an accelerating Universe for large value of time t, wherein the effective negative pressure induced by Chaplygin gas and bulk viscous pressure are driving the acceleration.
Generalized Ideal Gas Equations for Structureful Universe
Directory of Open Access Journals (Sweden)
Khalid Khan
2006-09-01
Full Text Available We have derived generalized ideal gas equations for a structureful universe consistingof all forms of matters. We have assumed a universe that contains superclusters. Superclusters arethen made of clusters. Each cluster can be further divided into smaller ones and so on. We havederived an expression for the entropy of such a universe. Our model is rather independent of thegeometry of the intermediate clusters. Our calculations are valid for a non-interacting universewithin non-relativistic limits. We suggest that structure formation can reduce the expansion rateof the universe.
Integrable discretization and deformation of the nonholonomic Chaplygin ball
Tsiganov, Andrey V.
2017-07-01
The rolling of a dynamically balanced ball on a horizontal rough table without slipping was described by Chaplygin using Abel quadratures. We discuss integrable discretizations and deformations of this nonholonomic system using the same Abel quadratures. As a by-product one gets a new geodesic flow on the unit two-dimensional sphere whose additional integrals of motion are polynomials in the momenta of fourth order.
Thermodynamics of an ideal generalized gas: I Thermodynamic laws
B. H. Lavenda
2005-01-01
The equations of state for an ideal generalized gas, like an ideal quantum gas, are expressed in terms of power laws of the temperature. The reduction of an ideal generalized gas to an ideal classical case occurs when the characteristic empirical temperature exponents in the thermal equation of state and in the absolute temperature coincide in contrast to the merger of an ideal quantum gas with an ideal classical gas in the high temperature limit. A corollary to Carnot's theorem is proved ass...
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In this paper we investigate the two-dimensional compressible isentropic Euler equations for Chaplygin gases. Under the assumption that the initial data is close to a constant state and the vorticity of the initial velocity vanishes, we prove the global existence of the smooth solution to the Cauchy problem for twodimensional flow of Chaplygin gases.
The global nonlinear stability of self-gravitating irrotational Chaplygin fluids in a FRW geometry
LeFloch, Philippe G
2015-01-01
We analyze the global nonlinear stability of FRW (Friedmann-Robertson-Walker) spacetimes in presence of an irrotational perfect fluid. We assume that the fluid is governed by the so-called (generalized) Chaplygin equation of state relating the pressure to the mass-energy density. We express the Einstein equations in wave gauge as a systems of coupled nonlinear wave equations and by performing a suitable conformal transformation, we are able to analyze the global behavior of solutions in future timelike directions. We establish that the (3+1)-spacetime metric and the mass density and velocity vector describing the evolution of the fluid remain globally close to a reference FRW solution, under small initial data perturbations. Our analysis provides also the precise asymptotic behavior of the perturbed solutions in the future directions.
Garrick, I E; Kaplan, Carl
1944-01-01
The differential equation of Chaplygin's jet problem is utilized to give a systematic development of particular solutions of the hodograph flow equations, which extends the treatment of Chaplygin into the supersonic range and completes the set of particular solutions. The particular solutions serve to place on a reasonable basis the use of velocity correction formulas for the comparison of incompressible and compressible flows. It is shown that the geometric-mean type of velocity correction formula introduced in part I has significance as an over-all type of approximation in the subsonic range. A brief review of general conditions limiting the potential flow of an adiabatic compressible fluid is given and application is made to the particular solutions, yielding conditions for the existence of singular loci in the supersonic range. The combining of particular solutions in accordance with prescribed boundary flow conditions is not treated in the present paper.
Garrick, I. E.; Kaplan, Carl
1944-01-01
The differential equation of Chaplygin's jet problem is utilized to give a systematic development of particular solutions of the hodograph flow equations, which extends the treatment of Chaplygin into the supersonic range and completes the set of particular solutions. The particular solutions serve to place on a reasonable basis the use of velocity correction formulas for the comparison of incompressible and compressible flows. It is shown that the geometric-mean type of velocity correction formula introduced in part I has significance as an over-all type of approximation in the subsonic range. A brief review of general conditions limiting the potential flow of an adiabatic compressible fluid is given and application is made to the particular solutions, yielding conditions for the existence of singular loci in the supersonic range. The combining of particular solutions in accordance with prescribed boundary flow conditions is not treated in the present paper.
Ideal Gas Laws: Experiments for General Chemistry
Deal, Walter J.
1975-01-01
Describes a series of experiments designed to verify the various relationships implicit in the ideal gas equation and shows that the success of the Graham's law effusion experiments can be explained by elementary hydrodynamics. (GS)
Generalized Gas Dynamic Equations for Microflows
Xu, Kun
2008-01-01
n an early approach, we proposed a kinetic model with multiple translational temperature [K. Xu, H. Liu and J. Jiang, Phys. Fluids {\\bf 19}, 016101 (2007)], to simulate non-equilibrium flows. In this paper, instead of using three temperatures in $x-$, $y-$, and $z$-directions, we are going to further define the translational temperature as a second-order symmetric tensor. Based on a multiple stage BGK-type collision model and the Chapman-Enskog expansion, the corresponding macroscopic gas dynamics equations in three-dimensional space will be derived. The zeroth-order expansion gives the 10 moment closure equations of Levermore [C.D. Levermore, J. Stat. Phys {\\bf 83}, pp.1021 (1996)]. To the 1st-order expansion, the derived gas dynamic equations can be considered as a regularization of Levermore's 10 moments equations. The new gas dynamic equations have the same structure as the Navier-Stokes equations, but the stress strain relationship in the Navier-Stokes equations is replaced by an algebraic equation with ...
Thermodynamics of an ideal generalized gas: I. Thermodynamic laws.
Lavenda, B H
2005-11-01
The equations of state for an ideal relativistic, or generalized, gas, like an ideal quantum gas, are expressed in terms of power laws of the temperature. In contrast to an ideal classical gas, the internal energy is a function of volume at constant temperature, implying that the ideal generalized gas will show either attractive or repulsive interactions. This is a necessary condition in order that the third law be obeyed and for matter to have an electromagnetic origin. The transition from an ideal generalized to a classical gas occurs when the two independent solutions of the subsidiary equation to Lagrange's equation coalesce. The equation of state relating the pressure to the internal energy encompasses the full range of cosmological scenarios, from the radiation to the matter dominated universes and finally to the vacuum energy, enabling the coefficient of proportionality, analogous to the Grüeisen ratio, to be interpreted in terms of the degrees of freedom related to the temperature exponents of the internal energy and the absolute temperature expressed in terms of a power of the empirical temperature. The limit where these exponents merge is shown to be the ideal classical gas limit. A corollary to Carnot's theorem is proved, asserting that the ratio of the work done over a cycle to the heat absorbed to increase the temperature at constant volume is the same for all bodies at the same volume. As power means, the energy and entropy are incomparable, and a new adiabatic potential is introduced by showing that the volume raised to a characteristic exponent is also the integrating factor for the quantity of heat so that the second law can be based on the property that power means are monotonically increasing functions of their order. The vanishing of the chemical potential in extensive systems implies that energy cannot be transported without matter and is equivalent to the condition that Clapeyron's equation be satisfied.
Thermodynamics of an ideal generalized gas: I. Thermodynamic laws
Lavenda, B. H.
2005-11-01
The equations of state for an ideal relativistic, or generalized, gas, like an ideal quantum gas, are expressed in terms of power laws of the temperature. In contrast to an ideal classical gas, the internal energy is a function of volume at constant temperature, implying that the ideal generalized gas will show either attractive or repulsive interactions. This is a necessary condition in order that the third law be obeyed and for matter to have an electromagnetic origin. The transition from an ideal generalized to a classical gas occurs when the two independent solutions of the subsidiary equation to Lagrange's equation coalesce. The equation of state relating the pressure to the internal energy encompasses the full range of cosmological scenarios, from the radiation to the matter dominated universes and finally to the vacuum energy, enabling the coefficient of proportionality, analogous to the Grüeisen ratio, to be interpreted in terms of the degrees of freedom related to the temperature exponents of the internal energy and the absolute temperature expressed in terms of a power of the empirical temperature. The limit where these exponents merge is shown to be the ideal classical gas limit. A corollary to Carnot's theorem is proved, asserting that the ratio of the work done over a cycle to the heat absorbed to increase the temperature at constant volume is the same for all bodies at the same volume. As power means, the energy and entropy are incomparable, and a new adiabatic potential is introduced by showing that the volume raised to a characteristic exponent is also the integrating factor for the quantity of heat so that the second law can be based on the property that power means are monotonically increasing functions of their order. The vanishing of the chemical potential in extensive systems implies that energy cannot be transported without matter and is equivalent to the condition that Clapeyron's equation be satisfied.
Generalizing Microdischarge Breakdown Scaling Laws for Pressure and Gas
Loveless, Amanda; Garner, Allen
2016-10-01
Shrinking device dimensions for micro- and nanoelectromechanical systems necessitates accurate breakdown voltage predictions for reliable operation. Additionally, one must accurately predict breakdown voltage to optimize system geometry for applications in microplasmas and micropropulsion. Traditional approaches use Paschen's law (PL) to predict breakdown, but PL fails at small gap distances ( 15 μm) where field emission dominates. Subsequent work derived scaling laws and analytic expressions for breakdown voltage in argon at atmospheric pressure. Applications at high (e.g. combustion) and low (e.g. vacuum nanoelectronics) pressures for various gases motivate the generalization of these models for pressure and gas. This work addresses these concerns by deriving scaling laws generalized for gap distance, pressure, and gas, while also specifically incorporating and exploring the impact of field enhancement and work function. We compare these analytic scaling laws to experimental data and particle-in-cell simulations. Funded by a U.S. Nuclear Regulatory Commission Nuclear Education Program Faculty Development Grant Program at Purdue University.
Strange star admitting Chaplygin equation of state in Finch-Skea spacetime
Bhar, Piyali
2015-10-01
In the present paper we propose a new model of an anisotropic strange star which admits the Chaplygin equation of state. The exterior spacetime is described by a Schwarzschild line element. The model is developed by assuming the Finch-Skea ansatz (Finch and Skea in Class. Quantum Gravity 6:467, 1989. We obtain the model parameters in closed form. Our model is free from a central singularity. Choosing some particular values for the parameter we show that our model corroborates the observational data of the strange star PSR J1614-2230 (Gangopadhyay et al. in Mon. Not. R. Astron. Soc. 431:3216, 2013.
Regular and chaotic dynamics in the rubber model of a Chaplygin top
Borisov, Alexey V.; Kazakov, Alexey O.; Pivovarova, Elena N.
2016-12-01
This paper is concerned with the rolling motion of a dynamically asymmetric unbalanced ball (Chaplygin top) in a gravitational field on a plane under the assumption that there is no slipping and spinning at the point of contact. We give a description of strange attractors existing in the system and discuss in detail the scenario of how one of them arises via a sequence of period-doubling bifurcations. In addition, we analyze the dynamics of the system in absolute space and show that in the presence of strange attractors in the system the behavior of the point of contact considerably depends on the characteristics of the attractor and can be both chaotic and nearly quasi-periodic.
Institute of Scientific and Technical Information of China (English)
Hakho HONG
2016-01-01
The zero dissipation limit to the contact discontinuities for one-dimensional com-pressible Navier-Stokes equations was recently proved for ideal polytropic gas (see Huang et al. [15, 22] and Ma [31]), but there is few result for general gases including ideal polytropic gas. We prove that if the solution to the corresponding Euler system of general gas satisfying (1.4) is piecewise constant with a contact discontinuity, then there exist smooth solutions to Navier-Stokes equations which converge to the inviscid solutions at a rate of κ14 as the heat-conductivity coeff cient κtends to zero. The key is to construct a viscous contact wave of general gas suitable to our proof (see Section 2). Notice that we have no need to restrict the strength of the contact discontinuity to be small.
Impact Analysis of Generalized Audit Software (GAS Utilization to Auditor Performances
Directory of Open Access Journals (Sweden)
Aries Wicaksono
2016-09-01
Full Text Available This study aimed to understand whether the use of Generalized Audit Software (GAS in the audit process have an impact on the auditors performance and to acquire conclusions in the evaluation form towards GAS audit process to provide a positive impact on the performance of auditors. The models used to evaluate the impact of GAS were Quantity of Work, Quality of Work, Job Knowledge, Creativeness, Cooperation, Dependability, Initiative, and Personal Qualities. The method used in this research was a qualitative method of analytical descriptive and evaluative, by analyzing the impact of the GAS implementation to the components of the user’s performance. The results indicate that the use of GAS has a positive impact on user’s performance components.
1975-01-01
The economic benefits of improved ocean condition, weather and ice forecasts by SEASAT satellites to the exploration, development and production of oil and natural gas in the offshore regions are considered. The results of case studies which investigate the effects of forecast accuracy on offshore operations in the North Sea, the Celtic Sea, and the Gulf of Mexico are reported. A methodology for generalizing the results to other geographic regions of offshore oil and natural gas exploration and development is described.
Friedman-Robertson-Walker Models with Late-Time Acceleration
Institute of Scientific and Technical Information of China (English)
Abdussattar; S. R. Prajapati2
2011-01-01
@@ In order to account for the observed cosmic acceleration, a modiGcation of the ansatz for the variation of density in Friedman-Robertson-Walker (FRW) FRW models given by Islam is proposed.The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that of a modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.%In order to account for the observed cosmic acceleration, a modification of the ansatz for the variation of density in Friedman-Robertson-Walker (FRW) FRW models given by Islam is proposed. The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that ora modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.
Directory of Open Access Journals (Sweden)
R. A. Mlinnik
2012-01-01
Full Text Available Objective: to analyze the impact of different detoxification techniques on pulmonary gas exchange function in patients with generalized peritonitis complicated by multiple organ failure. Subjects and methods. One hundred and thirty patients with generalized peritonitis were examined. According to the used detoxification techniques, the patients were divided into 5 groups. All the patients underwent a comprehensive examination, the key element of which was the evaluation of gas exchange parameters. Results. Membrane plasmapheresis and plasmapheresis with sodium hypochlorite infusion to the plasma filter in patients with peritonitis are shown to improve pulmonary blood oxygenation.
Friedman—Robertson—Walker Models with Late-Time Acceleration
Abdussattar; Prajapati, S. R.
2011-02-01
In order to account for the observed cosmic acceleration, a modification of the ansatz for the variation of density in Friedman—Robertson—Walker (FRW) FRW models given by Islam is proposed. The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that of a modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.
Friedmann-Robertson-Walker Models with Late-Time Acceleration
Abdussattar,
2016-01-01
In order to account for the observed cosmic acceleration, a modification of the ansatz for the variation of density in Friedman-Robertson-Walker (FRW) models given by Islam is proposed. The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that of a modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.
2013-10-28
... balance the protection and development of OCS resources. Specifically, we use the information collected to...) (electronic/digital form submittals). Subtotal 3,514 responses 3,514 $162,750 non-hour cost burden Compliance... Bureau of Ocean Energy Management Information Collection: General and Oil and Gas Production...
JETSET: Physics at LEAR with an Internal Gas Jet Target and an Advanced General Purpose Detector
2002-01-01
This experiment involves an internal gas cluster jet target surrounded by a compact general-purpose detector. The LEAR beam and internal jet target provide several important experimental features: high luminosity $ ( 10 ^{3} ^0 $ cm$^- ^{2} $ sec$^- ^{1} ) $, excellent mass resolution ($\\Delta
How do quantum numbers generally vary in the adiabatic transformation of an ideal gas?
Yarman, T.; L. Kholmetskii, A.
2011-10-01
We continue to analyse the known law of adiabatic transformation for an ideal gas PV5/3 = Constant, where P is the pressure and V is the volume, and following the approach of non-relativistic quantum mechanics which we suggested in a previous work (Yarman et al. 2010 Int. J. Phys. Sci. 5 1524). We explicitly determine the constant for the general parallelepiped geometry of a container. We also disclose how the quantum numbers associated with molecules of an ideal gas vary through an arbitrary adiabatic transformation. Physical implications of the results obtained are discussed.
How do quantum numbers generally vary in the adiabatic transformation of an ideal gas?
Institute of Scientific and Technical Information of China (English)
T. Yarman; A. L. Kholmetskii
2011-01-01
We continue to analyse the known law of adiabatic transformation for an ideal gas PV5/3 =Constant,where P is the pressure and V is the volume,and following the approach of non-relativistic quantum mechanics which we suggested in a previous work (Yarman et al.2010 Int.J.Phys.Sci.5 1524).We explicitly determine the constant for the general parallelepiped geometry of a container.We also disclose how the quantum numbers associated with molecules of an ideal gas vary through an arbitrary adiabatic transformation.Physical implications of the results obtained are discussed.
Generalized second-order slip boundary condition for nonequilibrium gas flows
Guo, Zhaoli; Qin, Jishun; Zheng, Chuguang
2014-01-01
It is a challenging task to model nonequilibrium gas flows within a continuum-fluid framework. Recently some extended hydrodynamic models in the Navier-Stokes formulation have been developed for such flows. A key problem in the application of such models is that suitable boundary conditions must be specified. In the present work, a generalized second-order slip boundary condition is developed in which an effective mean-free path considering the wall effect is used. By combining this slip scheme with certain extended Navier-Stokes constitutive relation models, we obtained a method for nonequilibrium gas flows with solid boundaries. The method is applied to several rarefied gas flows involving planar or curved walls, including the Kramers' problem, the planar Poiseuille flow, the cylindrical Couette flow, and the low speed flow over a sphere. The results show that the proposed method is able to give satisfied predictions, indicating the good potential of the method for nonequilibrium flows.
Generalized Density-Corrected Model for Gas Diffusivity in Variably Saturated Soils
DEFF Research Database (Denmark)
Chamindu, Deepagoda; Møldrup, Per; Schjønning, Per
2011-01-01
Accurate predictions of the soil-gas diffusivity (Dp/Do, where Dp is the soil-gas diffusion coefficient and Do is the diffusion coefficient in free air) from easily measureable parameters like air-filled porosity (ε) and soil total porosity (φ) are valuable when predicting soil aeration...... and the emission of greenhouse gases and gaseous-phase contaminants from soils. Soil type (texture) and soil density (compaction) are two key factors controlling gas diffusivity in soils. We extended a recently presented density-corrected Dp(ε)/Do model by letting both model parameters (α and β) be interdependent...... and also functions of φ. The extension was based on literature measurements on Dutch and Danish soils ranging from sand to peat. The parameter α showed a promising linear relation to total porosity, while β also varied with α following a weak linear relation. The thus generalized density-corrected (GDC...
2012-03-30
... AGENCY Draft NPDES General Permit for Discharges From the Oil and Gas Extraction Point Source Category to... Elimination System (NPDES) general permit regulating discharges from oil and gas wells in the Coastal... adversely affect an Essential Fish Habitat is subject to the consultation provisions of the...
General slip regime permeability model for gas flow through porous media
Zhou, Bo; Jiang, Peixue; Xu, Ruina; Ouyang, Xiaolong
2016-07-01
A theoretical effective gas permeability model was developed for rarefied gas flow in porous media, which holds over the entire slip regime with the permeability derived as a function of the Knudsen number. This general slip regime model (GSR model) is derived from the pore-scale Navier-Stokes equations subject to the first-order wall slip boundary condition using the volume-averaging method. The local closure problem for the volume-averaged equations is studied analytically and numerically using a periodic sphere array geometry. The GSR model includes a rational fraction function of the Knudsen number which leads to a limit effective permeability as the Knudsen number increases. The mechanism for this behavior is the viscous fluid inner friction caused by converging-diverging flow channels in porous media. A linearization of the GSR model leads to the Klinkenberg equation for slightly rarefied gas flows. Finite element simulations show that the Klinkenberg model overestimates the effective permeability by as much as 33% when a flow approaches the transition regime. The GSR model reduces to the unified permeability model [F. Civan, "Effective correlation of apparent gas permeability in tight porous media," Transp. Porous Media 82, 375 (2010)] for the flow in the slip regime and clarifies the physical significance of the empirical parameter b in the unified model.
Energy Technology Data Exchange (ETDEWEB)
Hugi, Ch.; Fuessler, J.; Sommerhalder, M.
2006-11-15
This comprehensive report for the Swiss Federal Office of Energy (SFOE) takes a look at the general conditions for the installation of gas-fired power plants in Europe. Combined cycle power stations are characterised and the associated power production costs are discussed. Also, the prices resulting from the internalisation of external costs are noted. The problems associated with carbon dioxide emissions are discussed and the trading of emission certificates is looked at. Also, nitrogen oxide emissions are examined and discussed. The use of waste heat from the combined cycle power stations is also examined. Further topics include subsidies and special credits for the gas industry in Europe and the granting of permission for the planning, construction, operation and dismantling of the power station facilities. The situation in various European countries is examined and the associated market distortion is commented on
A general model for Io's neutral gas clouds. I - Mathematical description
Smyth, W. H.; Combi, M. R.
1988-01-01
A general mathematical formalism for calculating the physical properties of any of Io's neutral gas clouds (Na, K, O, S, SO2) is presented. The dynamical effects of both the gravitational fields of Io and Jupiter and solar radiation pressure are included, in addition to the many complex space- and time-dependent interactions that occur between the neutral clouds and the plasma torus. The importance of this new model in studying both the plasma conditions prevalent in the inner planetary magnetosphere and the nature of Io's local atmosphere is discussed. A numerical method for evaluating the physical properties of the neutral clouds using the new model is described.
A generalized expression for lag-time in the gas-phase permeation of hollow tubes
Shah, K. K.; Nelson, H. G.; Johnson, D. L.; Hamaker, F. M.
1975-01-01
A generalized expression for the nonsteady-state parameter, lag-time, has been obtained from Fick's second law for gas-phase transport through hollow, cylindrical membranes. This generalized expression is simplified for three limiting cases of practical interest: (1) diffusion controlled transport, (2) phase boundary reaction control at the inlet surface, and (3) phase boundary reaction control at the outlet surface. In all three cases the lag-time expressions were found to be inversely proportional only to the diffusion coefficient and functionally dependent on the membrane radii. Finally, the lag-time expressions were applied to experimentally obtained lag-time data for alpha-phase titanium and alpha-phase iron.
A computable general equilibrium analysis of greenhouse gas reduction paths and scenarios
Energy Technology Data Exchange (ETDEWEB)
Iorwerth, A.A.; Bagnoli, P.; Dissou, Y.; Peluso, T.; Rudin, J. [Department of Finance, Ottawa, ON (Canada)
2000-10-31
Finance Canada conducted an analysis on behalf of the federal-provincial Climate Change Analysis and Modelling Group regarding policy options to reduce greenhouse gas (GHG) emissions. The Canadian sectoral general equilibrium model (CaSGEM) was used to simulate the Canadian economy using representative consumers and producers. The model describes the complete economy comprised of 51 sectors producing 59 goods and services. The model does not describe the transition costs of the path taken in adjusting to the new policy environment. Instead, it focuses on the Canadian economy after the impacts of new policies have been in place long enough to work themselves through the economy. It was suggested that at least some producers, particularly in electricity production, could easily replace GHG-intensive inputs with those which are less polluting. A table was included which showed the reduction in emissions from coal and natural gas predicted by the model for the electricity sector. The reduction in fuel use was also reported. It was concluded that there would be a long-run economic cost to implement the Kyoto agreement, but the cost is neither inconsequential nor enormous if the agreement is implemented in a cost-effective way. It was determined that the use of sector-specific emissions targets would add to the overall cost of implementing the Kyoto agreement without reducing the variation in economic impact across sectors. It was noted that technical assumptions have a significant bearing on the general impact and its distribution across sectors and provinces. tabs.
Evaluation of PM emissions from two in-service gas turbine general aviation aircraft engines
Yu, Zhenhong; Liscinsky, David S.; Fortner, Edward C.; Yacovitch, Tara I.; Croteau, Philip; Herndon, Scott C.; Miake-Lye, Richard C.
2017-07-01
We determined particulate matter (PM) emissions in the exhaust plumes from two gas turbine aircraft engines: a CF34-3A1 turbofan engine and a TPE331-6-252B turboprop engine in a dedicated study on in-service general aviation aircraft. The engine power states were from 16% to 100% engine thrust. Both nucleation and soot mode particles were observed from the emission exhausts of the CF34-3A1 engine but only soot particle mode was detected from the TPE331-6-252B engine. For the CF34-3A1 engine, the contribution of soot mode to total PM emissions was dominant at high power, while at decreased engine power states nucleation mode organic PM became important. PM emissions indices of the TPE331-6-252B engine were found to be generally larger than those of the CF34-3A1 engine. For both engines, medium power conditions (40-60% of thrust) yielded the lowest PM emissions. For the TPE331-6-252B engine, volatile PM components including organic and sulfate were more than 50% in mass at low power, while non-volatile black carbon became dominant at high power conditions such as takeoff.
Thermodynamics of an ideal generalized gas: II. Means of order alpha.
Lavenda, B H
2005-11-01
The property that power means are monotonically increasing functions of their order is shown to be the basis of the second laws not only for processes involving heat conduction, but also for processes involving deformations. This generalizes earlier work involving only pure heat conduction and underlines the incomparability of the internal energy and adiabatic potentials when expressed as powers of the adiabatic variable. In an L-potential equilibration, the final state will be one of maximum entropy, whereas in an entropy equilibration, the final state will be one of minimum L. Unlike classical equilibrium thermodynamic phase space, which lacks an intrinsic metric structure insofar as distances and other geometrical concepts do not have an intrinsic thermodynamic significance in such spaces, a metric space can be constructed for the power means: the distance between means of different order is related to the Carnot efficiency. In the ideal classical gas limit, the average change in the entropy is shown to be proportional to the difference between the Shannon and Rényi entropies for nonextensive systems that are multifractal in nature. The L potential, like the internal energy, is a Schur convex function of the empirical temperature, which satisfies Jensen's inequality, and serves as a measure of the tendency to uniformity in processes involving pure thermal conduction.
The general mechanisms of Cu cluster formation in the processes of condensation from the gas phase
Indian Academy of Sciences (India)
I V Chepkasov; Yu Ya Gafner; S L Gafner; S P Bardakhanov
2015-06-01
Technological applications of metallic clusters impose very strict requirements for particle size, shape, structure and defect density. Such geometrical characteristics of nanoparticles are mainly determined by the process of their growth. This work represents the basic mechanisms of cluster formation from the gas phase that has been studied on the example of copper. The process of Cu nanoclusters synthesis has been studied by the moleculardynamics method based on tight-binding potentials. It has been shown that depending on the size and temperature of the initial nanoclusters the process of nanoparticle formation can pass through different basic scenarios. The general conditions of different types of particles formation have been defined and clear dependence of the cluster shape from collision temperature of initial conglomerates has been shown. The simulation results demonstrate a very good agreement with the available experimental data. Thus, it has been shown that depending on the specific application of the synthesized particles or in electronics, where particles of a small size with a spherical shape are required, or in catalytic reactions, where the main factor of effectiveness is the maximum surface area with the help of temperature of the system it is possible to get the realization of a certain frequency of this or that scenario of the shape formation of nanocrystalline particles.
Csizmar, Clifford M.; Force, Dee Ann; Warner, Don L.
2011-01-01
As part of an NSF-funded Course Curriculum and Laboratory Improvement (CCLI) project that seeks, in part, to increase student exposure to scientific instrumentation, a gas chromatography experiment has been integrated into the second-semester general chemistry laboratory curriculum. The experiment uses affordable, commercially available equipment…
Pfennig, Brian W.; Schaefer, Amy K.
2011-01-01
A general chemistry laboratory experiment is described that introduces students to instrumental analysis using gas chromatography-mass spectrometry (GC-MS), while simultaneously reinforcing the concepts of mass percent and the calculation of atomic mass. Working in small groups, students use the GC to separate and quantify the percent composition…
2011-10-24
... entrainment caused by cooling water intake structures. EPA also proposes to require produced water effluent... the data with respect to further action in order to minimize potential adverse impacts caused by... Gulf of Mexico, or any potential gas spill is not covered by this general permit. Endangered...
Pfennig, Brian W.; Schaefer, Amy K.
2011-01-01
A general chemistry laboratory experiment is described that introduces students to instrumental analysis using gas chromatography-mass spectrometry (GC-MS), while simultaneously reinforcing the concepts of mass percent and the calculation of atomic mass. Working in small groups, students use the GC to separate and quantify the percent composition…
Csizmar, Clifford M.; Force, Dee Ann; Warner, Don L.
2011-01-01
As part of an NSF-funded Course Curriculum and Laboratory Improvement (CCLI) project that seeks, in part, to increase student exposure to scientific instrumentation, a gas chromatography experiment has been integrated into the second-semester general chemistry laboratory curriculum. The experiment uses affordable, commercially available equipment…
Thermodynamics of the Variable Modified Chaplyhin gas
Panigrahi, D
2015-01-01
A cosmological model with a new variant of Chaplygin gas obeying an equation of state(EoS), $P = A\\rho - \\frac{B}{\\rho^{\\alpha}}$ where $B= B_{0}a^{n}$ is investigated in the context of its thermodynamical behaviour. Here $B_{0}$ and $n$ are constants and $a$ is the scale factor. We show that the equation of state of this `Variable Modified Chaplygin gas' (VMCG) can describe the current accelerated expansion of the universe. Following Landau and Lifschitz's criteria we mainly discuss the classical thermodynamical stability of the model and find that the new parameter, $n$ introduced in VMCG plays a crucial role in determining the stability considerations and should be \\emph{negative.} We further observe that although the earlier model of J. Lu explains many of the current observational findings of different probes it fails the desirable tests of thermodynamical stability. We also note that for $n < 0$ our model points to a phantom type of expansion which is found to be compatible with current SNe Ia observ...
Staffieri, F; De Monte, V; De Marzo, C; Scrascia, F; Crovace, A
2010-06-01
The aim of this study was to evaluate the effects of a recruiting maneuver (RM) on lung aeration, gas exchange, and respiratory mechanics during general anesthesia in mechanically ventilated dogs. A thoracic computed tomography (CT) scan, an arterial blood sample, and measurement of respiratory mechanics were performed 10 min before (baseline) and both 5 and 30 min after a vital capacity RM in 10 dogs under general anesthesia. The RM was performed by inflating the lung at 40 cm H(2)O for 20 s. Lung aeration was estimated by analyzing the radiographic attenuation of the CT images. Lung aeration and gas exchange improved significantly 5 min after the RM compared to baseline and returned to values similar to baseline by 30 min. Static lung compliance was not significantly affected by the RM. An RM induces a temporary improvement in lung function in healthy dogs under general anesthesia.
Generalization of Eight Methods for Determining R in the Ideal Gas Law
Macnaughton, Donald B.
2007-01-01
The ideal gas law of physics and chemistry says that PV = nRT. This law is a statement of the relationship between four variables (P, V, n, and T) that reflect properties of a quantity of gas in a container. The law enables us to make accurate predictions of the value of any one of the four variables from the values of the other three. The symbol R (called the "molar gas constant") is the sole parameter or constant of the law. R stands for a fixed number that has been shown through experiment...
Energy Technology Data Exchange (ETDEWEB)
Yang, Ok Ryong
2004-01-15
This book introduces gas turbine cycle explaining general thing of gas turbine, full gas turbine cycle, Ericson cycle and Brayton cycle, practical gas turbine cycle without pressure loss, multiaxial type gas turbine cycle and special gas turbine cycle, application of basic theory on a study on suction-cooling gas turbine cycle with turbo-refrigerating machine using the bleed air, and general performance characteristics of the suction-cooling gas turbine cycle combined with absorption-type refrigerating machine.
A general solution and approximation for the diffusion of gas in a spherical coal sample
Institute of Scientific and Technical Information of China (English)
Wang Yucang; Xue Sheng; Xie Jun
2014-01-01
The square root relationship of gas release in the early stage of desorption is widely used to provide a simple and fast estimation of the lost gas in coal mines. However, questions arise as to how the relation-ship was theoretically derived, what are the assumptions and applicable conditions and how large the error will be. In this paper, the analytical solutions of gas concentration and fractional gas loss for the dif-fusion of gas in a spherical coal sample were given with detailed mathematical derivations based on the diffusion equation. The analytical solutions were approximated in case of small values of time and the error analyses associated with the approximation were also undertaken. The results indicate that the square root relationship of gas release is the first term of the approximation, and care must be taken in using the square root relationship as a significant error might be introduced with increase in the lost time and decrease in effective diameter of a spherical coal sample.
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures
Energy Technology Data Exchange (ETDEWEB)
Liu, Yen, E-mail: yen.liu@nasa.gov; Vinokur, Marcel [NASA Ames Research Center, Moffett Field, California 94035 (United States); Panesi, Marco; Sahai, Amal [University of Illinois, Urbana-Champaign, Illinois 61801 (United States)
2015-04-07
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model’s accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures
Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel
2015-04-01
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
K. S. Adegbie; F. I. Alao
2012-01-01
A mathematical model for thermal explosion in a combustible dusty gas containing fuel droplets with general Arrhenius reaction-rate laws, convective and radiative heat losses, and interphase heat exchange between gas and inert solid particles is investigated. The objective of the study is to examine the effects of interphase heat exchange between the gas and solid particles on (i) ignition of reacting gas, (ii) accumulation of heat by the solid particles during combustion process (iii) evapor...
McCann, Mary Ellen; Withington, D E; Arnup, S J; Davidson, A J; Disma, N; Frawley, G; Morton, N S; Bell, G; Hunt, R W; Bellinger, D C; Polaner, D M; Leo, A; Absalom, A R; von Ungern-Sternberg, B S; Izzo, F; Szmuk, P; Young, V; Soriano, S G; de Graaff, J C
BACKGROUND: The General Anesthesia compared to Spinal anesthesia (GAS) study is a prospective randomized, controlled, multisite, trial designed to assess the influence of general anesthesia (GA) on neurodevelopment at 5 years of age. A secondary aim obtained from the blood pressure data of the GAS
Thin-shell wormholes in Einstein-Born-Infeld theory
Eiroa, Ernesto F
2015-01-01
We construct spherically symmetric thin-shell wormholes with a generalized Chaplygin gas at the throat, in Born-Infeld electrodynamics coupled to Einstein gravity. We analyze their stability under radial perturbations.
Nitrogen-gas-stream cryostat for general X-ray diffraction studies
Energy Technology Data Exchange (ETDEWEB)
Cosier, J.; Glazer, A.M.
1986-04-01
A continuous nitrogen-flow cooling device, generally applicable to X-ray diffraction studies, is described. The device works in the range 77.4 to 323.0 K with a precision of +-0.1 K and a liquid-nitrogen constant consumption rate of 0.5 l h/sup -1/ over the whole temperature range. The supply vessel is unpressurised, so that refilling can be done without any observable influence on the cooling of the sample.
Inhomogeneous imperfect fluid inflation
Elizalde, Emilio
2016-01-01
A generalized equation of state corresponding to a model that includes a Chaplygin gas and a viscous term is investigated, in the context of the reconstruction program in scalar field cosmology. The corresponding inflationary model parameters can be conveniently adjusted in order to reproduce the most recent PLANCK data. The influence of the Chaplygin gas term contribution, in relation with previous models, is discussed. Exit from inflation is also shown to occur in the new model.
Davidson, Andrew J.; Morton, Neil S.; Arnup, Sarah J.; de Graaff, Jurgen C.; Disma, Nicola; Withington, Davinia E.; Frawley, Geoff; Hunt, Rodney W.; Hardy, Pollyanna; Khotcholava, Magda; von Ungern Sternberg, Britta S.; Wilton, Niall; Tuo, Pietro; Salvo, Ida; Ormond, Gillian; Stargatt, Robyn; Locatelli, Bruno Guido; McCann, Mary Ellen
2015-01-01
Background Post-operative apnea is a complication in young infants. Awake-regional anesthesia (RA) may reduce the risk; however the evidence is weak. The General Anesthesia compared to Spinal anesthesia (GAS) study is a randomized, controlled, trial designed to assess the influence of general anesthesia (GA) on neurodevelopment. A secondary aim is to compare rates of apnea after anesthesia. Methods Infants ≤ 60 weeks postmenstrual age scheduled for inguinal herniorraphy were randomized to RA or GA. Exclusion criteria included risk factors for adverse neurodevelopmental outcome and infants born < 26 weeks’ gestation. The primary outcome of this analysis was any observed apnea up to 12 hours post-operatively. Apnea assessment was unblinded. Results 363 patients were assigned to RA and 359 to GA. Overall the incidence of apnea (0 to 12 hours) was similar between arms (3% in RA and 4% in GA arms, Odds Ratio (OR) 0.63, 95% Confidence Intervals (CI): 0.31 to 1.30, P=0.2133), however the incidence of early apnea (0 to 30 minutes) was lower in the RA arm (1% versus 3%, OR 0.20, 95%CI: 0.05 to 0.91, P=0.0367). The incidence of late apnea (30 minutes to 12 hours) was 2% in both RA and GA arms (OR 1.17, 95%CI: 0.41 to 3.33, P=0.7688). The strongest predictor of apnea was prematurity (OR 21.87, 95% CI 4.38 to 109.24) and 96% of infants with apnea were premature. Conclusions RA in infants undergoing inguinal herniorraphy reduces apnea in the early post-operative period. Cardio-respiratory monitoring should be used for all ex-premature infants. PMID:26001033
Accelerating Expansion of the Universe
Chakraborty, Writambhara
2011-01-01
This thesis concentrates on the accelerated expansion of the Universe recently explored by measurements of redshift and luminosity-distance relations of type Ia Supernovae. We have considered a model of the universe filled with modified Chaplygin gas and barotropic fluid. The role of dynamical cosmological constant has been explored with Modified Chaplygin Gas as the background fluid. Various phenomenological models for \\Lambda have been studied in presence of the gravitational constant G to be constant or time dependent. A new form of the well known Chaplygin gas model has been presented by introducing inhomogeneity in the EOS. This model explains w=-1 crossing. An interaction of this model with the scalar field has also been investigated through a phenomenological coupling function. Tachyonic field has been depicted as dark energy model to represent the present acceleration of the Universe. A mixture of the tachyonic fluid has been considered with Generalized Chaplygin Gas to show the role of the later as a...
Holanda, R. F. L.; Pereira, S. H.; Santos da Costa, S.
2017-04-01
Nowadays, thanks to the improved precision of cosmological data, it has become possible to search for deviation from the general relativity theory with tests on large cosmic scales. Particularly, there is a class of modified gravity theories that breaks the Einstein equivalence principle (EEP) in the electromagnetic sector, generating variations of the fine structure constant, violations of the cosmic distance duality relation, and the evolution law of cosmic microwave background (CMB) radiation. In recent papers, this class of theories has been tested with angular diameter distances from galaxy clusters, type Ia supernovae, and CMB temperature. In this work we propose a new test by considering the most recent x-ray surface brightness observations of galaxy clusters jointly with type Ia supernovae and CMB temperature. The crucial point here is that we take into account the dependence of the x-ray gas mass fraction of galaxy clusters on possible variations of the fine structure constant and violations of the cosmic distance duality relation. Our basic result is that this new approach is competitive with the previous one, and it also does not show significant deviations from general relativity.
Directory of Open Access Journals (Sweden)
K. S. Adegbie
2012-01-01
Full Text Available A mathematical model for thermal explosion in a combustible dusty gas containing fuel droplets with general Arrhenius reaction-rate laws, convective and radiative heat losses, and interphase heat exchange between gas and inert solid particles is investigated. The objective of the study is to examine the effects of interphase heat exchange between the gas and solid particles on (i ignition of reacting gas, (ii accumulation of heat by the solid particles during combustion process (iii evaporation of the liquid fuel droplets, and (iv consumption of reacting gas concentration. The equations governing the physical model with realistic assumptions are stated and nondimensionalised leading to an intractable system of first-order coupled nonlinear differential equations, which is not amenable to exact methods of solution. Therefore, we present numerical solutions as well as different qualitative effects of varying interphase heat exchange parameter. Graphs and Table feature prominently to explain the results obtained.
Icardi, Matteo
2014-09-01
The inhomogeneous generalized population balance equation, which is discretized with the direct quadrature method of moment (DQMOM), is solved to predict the bubble size distribution (BSD) in a vertical pipe flow. The proposed model is compared with a more classical approach where bubbles are characterized with a constant mean size. The turbulent two-phase flow field, which is modeled using a Reynolds-Averaged Navier-Stokes equation approach, is assumed to be in local equilibrium, thus the relative gas and liquid (slip) velocities can be calculated with the algebraic slip model, thereby accounting for the drag, lift, and lubrication forces. The complex relationship between the bubble size distribution and the resulting forces is described accurately by the DQMOM. Each quadrature node and weight represents a class of bubbles with characteristic size and number density, which change dynamically in time and space to preserve the first moments of the BSD. The predictions obtained are validated against previously published experimental data, thereby demonstrating the advantages of this approach for large-scale systems as well as suggesting future extensions to long piping systems and more complex geometries. © 2014 Elsevier Inc.
Energy Technology Data Exchange (ETDEWEB)
NONE
1979-02-01
In 1969 General Motors began pilot operations of its Double Alkali SO2 Control System to determine the applicability of stack gas scrubbing to its industrial powerhouses. Using data from its two-year pilot plant development program, General Motors designed and constructed a complete industrial-scale demonstration plant capable of handling the emissions from all four coal fired boilers at the Chevrolet-Parma plant near Cleveland, Ohio. This report describes the results of the test program at Parma.
National Aeronautics and Space Administration — A new technique is proposed for improved trace gas detection and measurement that combines the high absorption depths afforded by mid-infrared Integrated Cavity...
Xingxing, Chen; Zhihui, Wang; Yongliang, Yu
2016-11-01
Hypersonic chemical non-equilibrium gas flows around blunt nosed bodies are studied in the present paper to investigate the Reynolds analogy relation on curved surfaces. With a momentum and energy transfer model being applied through boundary layers, influences of molecular dissociations and recombinations on skin frictions and heat fluxes are separately modeled. Expressions on the ratio of Cf / Ch (skin friction coefficient to heat flux) are presented along the surface of circular cylinders under the ideal dissociation gas model. The analysis indicates that molecular dissociations increase the linear distribution of Cf / Ch, but the nonlinear Reynolds analogy relation could ultimately be obtained in flows with larger Reynolds numbers and Mach numbers, where the decrease of wall heat flux by molecular recombinations signifies. The present modeling and analyses are also verified by the DSMC calculations on nitrogen gas flows.
Microscopic thin shell wormholes in magnetic Melvin universe
Mazharimousavi, S Habib; Amirabi, Z
2014-01-01
We construct thin shell wormholes in the magnetic Melvin universe. It is shown that in order to make a TSW in the Melvin spacetime the radius of the throat can not be larger than $\\frac{2}{B_{0}}$ in which $B_{0}$ is the magnetic field constant. We also analyze the stability of the constructed wormhole in terms of a linear perturbation around the equilibrium point. In our stability analysis we scan a full set of the Equation of States such as Linear Gas, Chaplygin Gas, Generalized Chaplygin Gas, Modified Generalized Chaplygin Gas and Logarithmic Gas. Finally we extend our study to the wormhole solution in the unified Melvin and Bertotti-Robinson spacetime. In this extension we show that for some specific cases, the local energy density is partially positive but the total energy which supports the wormhole is positive.
Microscopic thin-shell wormholes in magnetic Melvin universe
Energy Technology Data Exchange (ETDEWEB)
Mazharimousavi, S.H.; Halilsoy, M.; Amirabi, Z. [Eastern Mediterranean University, Department of Physics, North Cyprus, Mersin 10 (Turkey)
2014-05-15
We construct thin-shell wormholes in the magnetic Melvin universe. It is shown that in order to make a TSW in the Melvin spacetime the radius of the throat cannot be larger than (2)/(B{sub 0}), in which B{sub 0} is the magnetic field constant. We also analyze the stability of the constructed wormhole in terms of a linear perturbation around the equilibrium point. In our stability analysis we scan a full set of the Equation of States such as Linear Gas, Chaplygin Gas, Generalized Chaplygin Gas, Modified Generalized Chaplygin Gas, and Logarithmic Gas. Finally we extend our study to the wormhole solution in the unified Melvin and Bertotti-Robinson spacetime. In this extension we show that for some specific cases, the local energy density is partially positive but the total energy which supports the wormhole is positive. (orig.)
2013-11-22
...; (6) Hearing testimony may be provided orally or in written format. Commenters providing verbal... of the Administrative Procedure Act (APA), or any other law, to publish general notice of proposed... that NPDES general permits are permits, not rulemakings, under the APA and thus not subject to APA...
Stability of Thin-Shell Wormholes from Regular ABG Black Hole
Sharif, M
2016-01-01
In this paper, we construct thin-shell wormholes from regular Ayon-Beato and Garcia black hole by employing cut and paste formalism and examine their stability. We analyze attractive and repulsive characteristics of wormholes corresponding to outward and inward-directed acceleration components, respectively. A general equation of state is assumed as a linear perturbation to explore stability of these constructed wormholes with and without cosmological constant. We consider linear, logarithmic and Chaplygin gas models for exotic matter and evaluate stability regions for different values of charge. For horizon-free case, it is found that the generalized Chaplygin gas model provides maximum stable regions in de Sitter background while the modified generalized Chaplygin gas and logarithmic gas yield maximum stable regions in anti-de Sitter spacetime.
Stability of thin-shell wormholes from a regular ABG black hole
Sharif, M.; Mumtaz, Saadia
2017-01-01
In this paper, we construct thin-shell wormholes from a regular Ayon-Beato-Garcia black hole by employing cut and paste formalism and examine their stability. We analyze attractive and repulsive characteristics of the respective thin-shell wormholes. A general equation of state is assumed as a linear perturbation to explore stability of these constructed wormholes with and without cosmological constant. We consider linear, logarithmic and Chaplygin gas models for exotic matter and evaluate stability regions for different values of charge. It is found that the generalized Chaplygin gas model provides maximum stable regions in the de Sitter background while the modified generalized Chaplygin gas and logarithmic gas yield maximum stable regions in the anti-de Sitter spacetime.
On some generalization of the area theorem with applications to the problem of rolling balls
Chaplygin, Sergey A.
2012-04-01
This publication contributes to the series of RCD translations of Sergey Alexeevich Chaplygin's scientific heritage. Earlier we published three of his papers on non-holonomic dynamics (vol. 7, no. 2; vol. 13, no. 4) and two papers on hydrodynamics (vol. 12, nos. 1, 2). The present paper deals with mechanical systems that consist of several spheres and discusses generalized conditions for the existence of integrals of motion (linear in velocities) in such systems. First published in 1897 and awarded by the Gold Medal of Russian Academy of Sciences, this work has not lost its scientific significance and relevance. (In particular, its principal ideas are further developed and extended in the recent article "Two Non-holonomic Integrable Problems Tracing Back to Chaplygin", published in this issue, see p. 191). Note that non-holonomic models for rolling motion of spherical shells, including the case where the shells contain intricate mechanisms inside, are currently of particular interest in the context of their application in the design of ball-shaped mobile robots. We hope that this classical work will be estimated at its true worth by the English-speaking world.
Un modelo de equilibrio general para la fijación de precios del gas natural en México
Directory of Open Access Journals (Sweden)
Dagobert L. Brito
2005-01-01
Full Text Available La Comisión Reguladora de Energía de México ha implantado una regla deen la ce ha cia atrás para unir el pre cio del gas na tu ral me xi ca no al pre cio delgas na tu ral de Te jas. Este en sa yo de mues tra que en una eco no mía abier ta,en la que los agen tes es co gen en tre el gas y otros com bus ti bles, y en la que lafun ción de den si dad que des cri be la dis tri bu ción de los agen tes a lo lar go delgasoducto puede tener intervalos vacíos y puntos de acumulación, la regla deen la ce ha cia atrás es óp ti ma en el sen ti do de Pa re to.
Directory of Open Access Journals (Sweden)
Favergeon L.
2013-05-01
Full Text Available Understanding the industrial reactors behavior is a difficult task in the case of solid state reactions such as solid-gas reactions. Indeed the solid phase is a granular medium through which circulate gaseous reactants and products. The properties of such a medium are modified in space and time due to reactions occurring at a microscopic scale. The thermodynamic conditions are driven not only by the operating conditions but also by the heat and mass transfers in the reactor. We propose to numerically resolve the thermohydraulic equations combined with kinetic laws which describe the heterogeneous reactions. The major advantage of this approach is due to the large variety of kinetic models of grains transformation (~40 compared to the usual approach, especially in the case of surface nucleation and growth processes which need to quantitatively describe the grain conversion kinetics at a microscopic scale due to nucleation frequency and growth rate laws obtained in separate isothermal and isobaric experiments. The heat and mass transfers terms entering in the balance equations at a macroscopic scale depend on the kinetics evaluated at the microscopic scale. These equations give the temperature and partial pressure in the reactor, which in turn influence the microscopic kinetic behavior.
Directory of Open Access Journals (Sweden)
Edoardo Magnone
2012-11-01
Full Text Available In today’s economy, one of the most important national indicators of economic growth performance is the country’s ability to produce new technology—and use it responsibly and efficiently—for environmental protection or energy conservation, production and consumption in agreement with international standards. The purpose of this study is to identify the Research and Development (R&D capability in the area of environmentally friendly technologies in China, Japan and Korea over the last twenty years. As the field is very wide, Water-Gas Shift (WGS reaction technologies were taken as a case study for the purpose of this article. During 1990–2011 a total of 788 papers in the field of WGS technologies were published by scientists in China, Japan and Korea. China was the top producing country with 394 papers (50% followed by Japan with 250 papers (32%, and Korea with 144 papers (18%. The growth of the literature in the field was found to be exponential in nature for China. The R&D capabilities were found to correlate directly with the Gross Domestic Expenditures on R&D (GERD, Researchers in Full-time equivalents (FTE, and other economic parameters.
Institute of Scientific and Technical Information of China (English)
赵娟; 王银霞
2012-01-01
In this paper we prove that global existence of smooth solutions to Cauchy problem for compressible isentropic Euler equations for Chaplygin gases or Karman-Tsien gases in three space dimensions , provided that the initial data are obtained by adding a small smooth perturbation with compact support to a constant state and the vorticity of the initial velocity vanishes.%研究了三维可压等熵Euler方程Cauchy问题光滑解的整体存在性.如果初值是一个常状态的小扰动并且初速度的旋度等于零,证明了三维可压等熵Euler方程Cauchy问题光滑解的整体存在性.
Paradox of soft singularity crossing and its resolution by distributional cosmological quantities
Keresztes, Zoltán; Gergely, László Á.; Kamenshchik, Alexander Yu.
2012-09-01
A cosmological model of a flat Friedmann universe filled with a mixture of anti-Chaplygin gas and dustlike matter exhibits a future soft singularity, where the pressure of the anti-Chaplygin gas diverges (while its energy density is finite). Despite infinite tidal forces the geodesics pass through the singularity. Because of the dust component, the Hubble parameter has a nonzero value at the encounter with the singularity, therefore the dust implies further expansion. With continued expansion however, the energy density and the pressure of the anti-Chaplygin gas would become ill-defined hence from the point of view of the anti-Chaplygin gas only a contraction is allowed. Paradoxically, the universe in this cosmological model would have to expand and contract simultaneously. This obviously could not happen. We solve the paradox by redefining the anti-Chaplygin gas in a distributional sense. Then a contraction could follow the expansion phase at the singularity at the price of a jump in the Hubble parameter. Although such an abrupt change is not common in any cosmological evolution, we explicitly show that the set of Friedmann, Raychaudhuri and continuity equations are all obeyed both at the singularity and in its vicinity. We also prove that the Israel junction conditions are obeyed through the singular spatial hypersurface. In particular we enounce and prove a more general form of the Lanczos equation.
A New Generalized Thermal Wind Equation and its Application to Zonal Flows on the Gas Giant Planets
Marcus, Philip; Tollefson, Joshua; de Pater, Imke
2015-11-01
For baroclinic, rapidly-rotating flows, the Thermal Wind Equation (TWE) describes how the flow varies along the rotation axis as a function of temperature gradients. The TWE works well for many laboratory and atmospheric flows on Earth. We show that the TWE also works well for the zonal (west-to-east) flows u on Jupiter. However, our recent observations of Neptune's zonal flows not only do not fit the TWE, but also have the incorrect ``sign.'' When an atmosphere's longitudinally-averaged temperature is warmer at the equator than at the mid-latitudes, the TWE indicates that u increases with height in the atmosphere. The change in u as a function of height on Neptune has the opposite sign. Here, we show that the high-velocities of u on Neptune make the cyclostrophic terms (i.e., some of the nonlinear terms proportional to u2) large, and these terms are dropped in the standard derivation of the TWE. When the cyclostrophic terms are retained, a more generalized TWE is obtained that both qualitatively and quantitatively agrees with the observations of the change in u as a function of height in Neptune's atmosphere. We show that both the standard and generalized TWE for zonal flows can be extended to the equator despite the fact that the Coriolis force vanishes there.
Fabris, J C; Rodrigues, D C; Batista, C E M; Daouda, M H
2012-01-01
We review the difficulties of the generalized Chaplygin gas model to fit observational data, due to the tension between background and perturbative tests. We argue that such issues may be circumvented by means of a self-interacting scalar field representation of the model. However, this proposal seems to be successful only if the self-interacting scalar field has a non-canonical form. The latter can be implemented in Rastall's theory of gravity, which is based on a modification of the usual matter conservation law. We show that, besides its application to the generalized Chaplygin gas model, other cosmological models based on Rastall's theory have many interesting and unexpected new features.
Huggett, Daniel J.; Majumdar, Alok
2013-01-01
Cryogenic propellants are readily heated when used. This poses a problem for rocket engine efficiency and effective boot-strapping of the engine, as seen in the "hot" LOX (Liquid Oxygen) problem on the S-1 stage of the Saturn vehicle. In order to remedy this issue, cryogenic fluids were found to be sub-cooled by injection of a warm non-condensing gas. Experimental results show that the mechanism behind the sub-cooling is evaporative cooling. It has been shown that a sub-cooled temperature difference of approximately 13 deg F below saturation temperature [1]. The phenomenon of sub-cooling of cryogenic propellants by a non-condensing gas is not readily available with the General Fluid System Simulation Program (GFSSP) [2]. GFSSP is a thermal-fluid program used to analyze a wide variety of systems that are directly impacted by thermodynamics and fluid mechanics. In order to model this phenomenon, additional capabilities had to be added to GFSSP in the form of a FORTRAN coded sub-routine to calculate the temperature of the sub-cooled fluid. Once this was accomplished, the sub-routine was implemented to a GFSSP model that was created to replicate an experiment that was conducted to validate the GFSSP results.
Brown, D. H.; Corman, J. C.
1976-01-01
Ten energy conversion systems are defined and analyzed in terms of efficiency. These include: open-cycle gas turbine recuperative; open-cycle gas turbine; closed-cycle gas turbine; supercritical CO2 cycle; advanced steam cycle; liquid metal topping cycle; open-cycle MHD; closed-cycle inert gas MHD; closed-cycle liquid metal MHD; and fuel cells. Results are presented.
Energy Technology Data Exchange (ETDEWEB)
Li, Jun; Yang, Rongjia; Chen, Bohai, E-mail: litianshiiiii@163.com, E-mail: yangrj08@gmail.com, E-mail: bchenphy@163.com [College of Physical Science and Technology, Hebei University, No. 180, Wusi East Road, Baoding, 071002 China (China)
2014-12-01
We apply the Statefinder hierarchy and the growth rate of matter perturbations to discriminate modified Chaplygin gas (MCG), generalized Chaplygin gas (GCG), superfluid Chaplygin gas (SCG), purely kinetic k-essence (PKK), and ΛCDM model. We plot the evolutional trajectories of these models in the Statefinder plane and in the composite diagnostic plane. We find that GCG, MCG, SCG, PKK, and ΛCDM can be distinguished well from each other at the present epoch by using the composite diagnostic (ε(z), S{sup (1)}{sub 5}). Using other combinations, such as (S{sup (1)}{sub 3}, S{sup (1)}{sub 4}), (S{sup (1)}{sub 3}, S{sub 5}), (ε(z), S{sup (1)}{sub 3}), and (ε(z), S{sub 4}), some of these five dark energy models cannot be distinguished.
Li, Jun; Yang, Rongjia; Chen, Bohai
2014-12-01
We apply the Statefinder hierarchy and the growth rate of matter perturbations to discriminate modified Chaplygin gas (MCG), generalized Chaplygin gas (GCG), superfluid Chaplygin gas (SCG), purely kinetic k-essence (PKK), and ΛCDM model. We plot the evolutional trajectories of these models in the Statefinder plane and in the composite diagnostic plane. We find that GCG, MCG, SCG, PKK, and ΛCDM can be distinguished well from each other at the present epoch by using the composite diagnostic {epsilon(z), S(1)5}. Using other combinations, such as {S(1)3, S(1)4}, {S(1)3, S5}, {epsilon(z), S(1)3}, and {epsilon(z), S4}, some of these five dark energy models cannot be distinguished.
33 CFR 127.401 - Maintenance: General.
2010-07-01
...) WATERFRONT FACILITIES WATERFRONT FACILITIES HANDLING LIQUEFIED NATURAL GAS AND LIQUEFIED HAZARDOUS GAS Waterfront Facilities Handling Liquefied Natural Gas Maintenance § 127.401 Maintenance: General. The...
33 CFR 127.503 - Training: General.
2010-07-01
...) WATERFRONT FACILITIES WATERFRONT FACILITIES HANDLING LIQUEFIED NATURAL GAS AND LIQUEFIED HAZARDOUS GAS Waterfront Facilities Handling Liquefied Natural Gas Personnel Training § 127.503 Training: General....
Observational Constraints on the Unified Dark-Energy-Dark-Matter Model
Institute of Scientific and Technical Information of China (English)
WU Pu-Xun; YU Hong-Wei
2007-01-01
We investigate the constraints on a generalized Chaplygin gas (GCC) model using the gold sample type-Ia supernovae (She Ia) data, the new Supernova Legacy Survey (SNLS) She Ia data and the size of baryonic acoustic oscillation peak found in Sloan Digital Sky Survey (SDSS). In a spatially flat universe case we obtain, at a 95.4% confidence level, As = 0.76-0.07+0.07 and α = 0.028-0.238+0.322. Our results are consistent with the ACDM model (α = 0), but rule out the standard Chaplygin gas model (α = 1).
Frawley, Geoff; Bell, Graham; Disma, Nicola; Withington, Davinia E.; de Graaff, Jurgen C.; Morton, Neil S.; McCann, Mary Ellen; Arnup, Sarah J.; Bagshaw, Oliver; Wolfler, Andrea; Bellinger, David; Davidson, Andrew J.
2015-01-01
Background Awake regional anesthesia (RA) is a viable alternative to general anesthesia (GA) for infants undergoing lower abdominal surgery. Benefits include lower incidence of postoperative apnea and avoidance of anesthetic agents that may increase neuroapoptosis and worsen neurocognitive outcomes. The General Anesthesia compared to Spinal anesthesia (GAS) study compares neurodevelopmental outcomes following awake RA or GA in otherwise healthy infants. Our aim was to describe success and failure rates of RA in this study and report factors associated with failure. Methods This was a nested cohort study within a prospective randomized, controlled, observer blind, equivalence trial. Seven hundred twenty two infants ≤ 60 weeks postmenstrual age, scheduled for herniorrhaphy under anesthesia were randomly assigned to receive RA (spinal, caudal epidural or combined spinal caudal anesthetic) or GA with sevoflurane. The data of 339 infants, where spinal or combined spinal caudal anesthetic was attempted, was analyzed. Possible predictors of failure were assessed including: patient factors, technique, experience of site and anesthetist and type of local anesthetic. Results RA was sufficient for the completion of surgery in 83.2% of patients. Spinal anesthesia was successful in 86.9% of cases and combined spinal caudal anesthetic in 76.1%. Thirty four patients required conversion to GA and an additional 23 (6.8%) required brief sedation. Bloody tap on the first attempt at lumbar puncture was the only risk factor significantly associated with block failure (OR = 2.46). Conclusions The failure rate of spinal anesthesia was low. Variability in application of combined spinal caudal anesthetic limited attempts to compare the success of this technique to spinal alone. PMID:26001028
Radhakrishnan, Krishnan
1994-01-01
LSENS, the Lewis General Chemical Kinetics and Sensitivity Analysis Code, has been developed for solving complex, homogeneous, gas-phase chemical kinetics problems and contains sensitivity analysis for a variety of problems, including nonisothermal situations. This report is part 1 of a series of three reference publications that describe LENS, provide a detailed guide to its usage, and present many example problems. Part 1 derives the governing equations and describes the numerical solution procedures for the types of problems that can be solved. The accuracy and efficiency of LSENS are examined by means of various test problems, and comparisons with other methods and codes are presented. LSENS is a flexible, convenient, accurate, and efficient solver for chemical reaction problems such as static system; steady, one-dimensional, inviscid flow; reaction behind incident shock wave, including boundary layer correction; and perfectly stirred (highly backmixed) reactor. In addition, the chemical equilibrium state can be computed for the following assigned states: temperature and pressure, enthalpy and pressure, temperature and volume, and internal energy and volume. For static problems the code computes the sensitivity coefficients of the dependent variables and their temporal derivatives with respect to the initial values of the dependent variables and/or the three rate coefficient parameters of the chemical reactions.
Rahman, Khondokar M; Melville, Lynsey; Fulford, David; Huq, Sm Imamul
2017-08-01
Calculations towards determining the greenhouse gas mitigation capacity of a small-scale biogas plant (3.2 m(3) plant) using cow dung in Bangladesh are presented. A general life cycle assessment was used, evaluating key parameters (biogas, methane, construction materials and feedstock demands) to determine the net environmental impact. The global warming potential saving through the use of biogas as a cooking fuel is reduced from 0.40 kg CO2 equivalent to 0.064 kg CO2 equivalent per kilogram of dung. Biomethane used for cooking can contribute towards mitigation of global warming. Prior to utilisation of the global warming potential of methane (from 3.2 m(3) biogas plant), the global warming potential is 13 t of carbon dioxide equivalent. This reduced to 2 t as a result of complete combustion of methane. The global warming potential saving of a bioenergy plant across a 20-year life cycle is 217 t of carbon dioxide equivalent, which is 11 t per year. The global warming potential of the resultant digestate is zero and from construction materials is less than 1% of total global warming potential. When the biogas is used as a fuel for cooking, the global warming potential will reduce by 83% compare with the traditional wood biomass cooking system. The total 80 MJ of energy that can be produced from a 3.2 m(3) anaerobic digestion plant would replace 1.9 t of fuel wood or 632 kg of kerosene currently used annually in Bangladesh. The digestate can also be used as a nutrient rich fertiliser substituting more costly inorganic fertilisers, with no global warming potential impact.
Energy Technology Data Exchange (ETDEWEB)
Lopes, Carlos A.; Moraes, Claudia C.D. [Eletricidade de Sao Paulo S.A. (ELETROPAULO), Sao Paulo, SP (Brazil); Fonseca, Carlos H.F. [Centrais Eletricas de Santa Catarina S.A., Florianopolis, SC (Brazil); Silva, Clecio Fabricio da; Alves, Ricardo P. [Companhia Paranaense de Energia (COPEL), Curitiba, PR (Brazil); Sposito, Edivaldo Soares; Hulle, Lutero [Espirito Santo Centrais Eletricas S.A. (ESCELSA), Vitoria, ES (Brazil); S. Martins, Icaro da [Centrais Eletricas do Norte do Brasil S.A. (ELETRONORTE), Belem, PA (Brazil); Vilhena, Joao Luiz S. de [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil); Fagundes, Zaluar Aquino [Companhia Estadual de Energia Eletrica do Estado do Rio Grande do Sul, Porto Alegre, RS (Brazil)
1996-12-31
An increase in the consumption of natural gas in Brazil is an expected fact in what concerns energetic planning. This work presents the existing situation in what concerns natural gas utilization in the main world economies, as well as an analysis of the participation of this fuel among the energy final consumption per sources. The Brazilian consumption of natural gas is also analysed as well as the international agreement between Brazil and Bolivia for natural gas commercialization. Some legal, institutional and political aspects related to natural gas commercialization are also discussed. Finally, several benefits to be brought by the utilization of natural gas are presented 10 refs., 3 tabs.
33 CFR 127.601 - Fire equipment: General.
2010-07-01
...) WATERFRONT FACILITIES WATERFRONT FACILITIES HANDLING LIQUEFIED NATURAL GAS AND LIQUEFIED HAZARDOUS GAS Waterfront Facilities Handling Liquefied Natural Gas Firefighting § 127.601 Fire equipment: General. (a)...
Statefinder Diagnostic for Dark Energy Models in Bianchi I Universe
Sharif, M
2013-01-01
In this paper, we investigate the statefinder, the deceleration and equation of state parameters when universe is composed of generalized holographic dark energy or generalized Ricci dark energy for Bianchi I universe model. These parameters are found for both interacting as well as non-interacting scenarios of generalized holographic or generalized Ricci dark energy with dark matter and generalized Chaplygin gas. We explore these parameters graphically for different situations. It is concluded that these models represent accelerated expansion of the universe.
Gravitational Collapse With Dark Energy And Dark Matter In Ho\\v{r}ava-Lifshitz Gravity
Rudra, Prabir
2013-01-01
In this work, the collapsing process of a spherically symmetric star, made of dust cloud, is studied in Ho\\v{r}ava Lifshitz gravity in the background of Chaplygin gas dark energy. Two different classes of Chaplygin gas, namely, New variable modified Chaplygin gas and generalized cosmic Chaplygin gas are considered for the collapse study. Graphs are drawn to characterize the nature and to determine the possible outcome of gravitational collapse. A comparative study is done between the collapsing process in the two different dark energy models. It is found that for open and closed universe, collapse proceeds with an increase in black hole mass, the only constraint being that, relatively smaller values of $\\Lambda$ has to be considered in comparison to $\\lambda$. But in case of flat universe, possibility of the star undergoing a collapse in highly unlikely. Moreover it is seen that the most favourable environment for collapse is achieved when a combination of dark energy and dark matter is considered, both in th...
Davidson, Andrew J; Disma, Nicola; De Graaff, Jurgen C; Withington, Davinia E; Dorris, Liam; Bell, Graham; Stargatt, Robyn; Bellinger, David C; Schuster, Tibor; Arnup, Sarah J; Hardy, Pollyanna; Hunt, Rodney W; Takagi, Michael J; Giribaldi, Gaia; Hartmann, Penelope L; Salvo, Ida; Morton, Neil S; Von Ungern Sternberg, Britta S; Locatelli, Bruno Guido; Wilton, Niall; Lynn, Anne; Thomas, Joss J; Polaner, David; Bagshaw, Oliver; Szmuk, Peter; Absalom, Anthony R; Frawley, Geoff; Berde, Charles; Ormond, Gillian D; Marmor, Jacki; Mccann, Mary Ellen
2016-01-01
Background Preclinical data suggest that general anaesthetics affect brain development. There is mixed evidence from cohort studies that young children exposed to anaesthesia can have an increased risk of poor neurodevelopmental outcome. We aimed to establish whether general anaesthesia in infancy h
Davidson, Andrew J; Disma, Nicola; de Graaff, Jurgen C; Withington, Davinia E; Dorris, Liam; Bell, Graham; Stargatt, Robyn; Bellinger, David C; Schuster, Tibor; Arnup, Sarah J; Hardy, Pollyanna; Hunt, Rodney W; Takagi, Michael J; Giribaldi, Gaia; Hartmann, Penelope L; Salvo, Ida; Morton, Neil S; von Ungern Sternberg, Britta S; Locatelli, Bruno Guido; Wilton, Niall; Lynn, Anne; Thomas, Joss J; Polaner, David; Bagshaw, Oliver; Szmuk, Peter; Absalom, Anthony R; Frawley, Geoff; Berde, Charles; Ormond, Gillian D; Marmor, Jacki; McCann, Mary Ellen
2016-01-01
BACKGROUND: Preclinical data suggest that general anaesthetics affect brain development. There is mixed evidence from cohort studies that young children exposed to anaesthesia can have an increased risk of poor neurodevelopmental outcome. We aimed to establish whether general anaesthesia in infancy
Origin of natural gas; Tennen gas no kigen
Energy Technology Data Exchange (ETDEWEB)
Katayama, Y. [The Institute of Applied Energy, Tokyo (Japan)
1996-03-20
Natural gas, which is a general term of flammable hydrocarbon gases such as methane, is classified by origin into the following categories : (1) oil field gas (oil gas), (2) aquifers (bacteria-fermented methane), (3) coal gas (coal field gas), and (4) abiogenetic gas. The natural gas which has (1-4) origins and is now used as resource in a large quantity is (1) oil field gas. This gas is a hydrocarbon gas recovered in the production process of petroleum and contains components such as ethane, propane and butane. To the contrary, (2) aquifers and (3) coal gas have methane as main component. As (4) abiogenetic methane, there are gas formed in inorganic reaction in activities of submarine volcanos and deep gas (earth origin gas). Oil field gas has kerogen origin. Aquifers were formed by fermentation of organic matters. Coal gas was formed by coalification of vitrinite. As abiogenetic methane, there are inorganic reaction formation gas and deep gas, the latter of which exists little as resource. 7 refs., 11 figs., 1 tab.
Natural Gas Acquisition Program
General Services Administration — The "NGAP" system is a web based application which serves NGAP GSA users for tracking information details for various natural gas supply chain elements like Agency,...
(N+1)-dimensional Lorentzian evolving wormholes supported by polytropic matter
Energy Technology Data Exchange (ETDEWEB)
Cataldo, Mauricio [Universidad del Bio-Bio, Departamento de Fisica, Facultad de Ciencias, Concepcion (Chile); Arostica, Fernanda; Bahamonde, Sebastian [Universidad de Concepcion, Departamento de Fisica, Concepcion (Chile)
2013-08-15
In this paper we study (N+1)-dimensional evolving wormholes supported by energy satisfying a polytropic equation of state. The considered evolving wormhole models are described by a constant redshift function and generalizes the standard flat Friedmann-Robertson-Walker spacetime. The polytropic equation of state allows us to consider in (3+1)-dimensions generalizations of the phantom energy and the generalized Chaplygin gas sources. (orig.)
de Souza, R. S.
2003-08-01
Observações de Supernovas do tipo Ia mostram que a expansão do Universo está acelerando. Segundo as equações de Einstein uma componente com pressão negativa (energia escura) é necessária para explicar a aceleração cósmica. Além da energia escura é usualmente admitido que no Universo há também uma matéria exótica com pressão zero, que é chamada de matéria escura. Essa componente possui um papel fundamental na formação de estruturas no Universo. Recentemente tem se explorado a possibilidade de que matéria e energia escura poderiam ser unificadas através de uma única componente, que tem sido denominada de quartessência. Um exemplo de fluido com essas características é o Gás de Chaplygin Generalizado, que possui uma equação de estado da forma p = -A/ra. Inicialmente consideramos o caso especial a = 1 (gás de Chaplygin) e vinculamos parâmetros do modelo utilizando observações em raios-X do satélite Chandra da fração de massa de gás em aglomerados de galáxias. Uma comparação dos vínculos obtidos com esse teste com outros testes, tais como supernovas e idade do Universo, mostra que esse teste é bastante restritivo. Exibiremos ainda resultados para o caso em que a curvatura é nula e o parâmetro a está compreendido no intervalo -1 < a 1.
Chang, Seungwoo; Graham, Wendy D.; Hwang, Syewoon; Muñoz-Carpena, Rafael
2016-08-01
Projecting water deficit under various possible future climate scenarios depends on the choice of general circulation model (GCM), reference evapotranspiration (ET0) estimation method, and Representative Concentration Pathway (RCP) trajectory. The relative contribution of each of these factors must be evaluated in order to choose an appropriate ensemble of future scenarios for water resources planning. In this study variance-based global sensitivity analysis and Monte Carlo filtering were used to evaluate the relative sensitivity of projected changes in precipitation (P), ET0, and water deficit (defined here as P-ET0) to choice of GCM, ET0 estimation method, and RCP trajectory over the continental United States (US) for two distinct future periods: 2030-2060 (future period 1) and 2070-2100 (future period 2). A total of 9 GCMs, 10 ET0 methods, and 3 RCP trajectories were used to quantify the range of future projections and estimate the relative sensitivity of future projections to each of these factors. In general, for all regions of the continental US, changes in future precipitation are most sensitive to the choice of GCM, while changes in future ET0 are most sensitive to the choice of ET0 estimation method. For changes in future water deficit, the choice of GCM is the most influential factor in the cool season (December-March), and the choice of ET0 estimation method is most important in the warm season (May-October) for all regions except the Southeast US, where GCMs and ET0 have approximately equal influence throughout most of the year. Although the choice of RCP trajectory is generally less important than the choice of GCM or ET0 method, the impact of RCP trajectory increases in future period 2 over future period 1 for all factors. Monte Carlo filtering results indicate that particular GCMs and ET0 methods drive the projection of wetter or drier future conditions much more than RCP trajectory; however, the set of GCMs and ET0 methods that produce wetter or
Energy Technology Data Exchange (ETDEWEB)
Talukder, Srijeeta; Sen, Shrabani [Department of Chemistry, University of Calcutta, 92 A P C Road, Kolkata 700 009 (India); Sharma, Rahul [Department of Chemistry, St. Xavier’s College, 30 Mother Teresa Sarani, Kolkata 700 016 (India); Banik, Suman K., E-mail: skbanik@bic.boseinst.ernet.in [Department of Chemistry, Bose Institute, 93/1 A P C Road, Kolkata 700 009 (India); Chaudhury, Pinaki, E-mail: pinakc@rediffmail.com [Department of Chemistry, University of Calcutta, 92 A P C Road, Kolkata 700 009 (India)
2014-03-18
Highlights: • We demonstrate a general strategy to map out reaction paths irrespective of the number of kinetic steps involved. • The objective function proposed does not need the information of gradient norm and eigenvalue of Hessian matrix explicitly. • A stochastic optimizer Simulated Annealing is used in searching reaction path. • The strategy is applied in mapping out the path for conformational changes in pure Ar clusters and Ar{sub N}Xe mixed clusters. - abstract: In this paper we demonstrate a general strategy to map out reaction paths irrespective of the number of kinetic steps required to bring about the change. i.e., whether the transformation takes place in a single step or in multiple steps with the appearance of intermediates. The objective function proposed is unique and works equally well for a concerted or a multiple step pathway. As the objective function proposed does not explicitly involves the calculation of the gradient of the potential energy function or the eigenvalues of the Hessian Matrix during the iterative process, the calculation is computationally economical. To map out the reaction path, we cast the entire problem as one of optimization and the solution is done with the use of the stochastic optimizer Simulated Annealing. The formalism is tested on Argon clusters (Ar{sub N}) and Argon clusters singly doped with Xenon (Ar{sub N-1}Xe). The size of the systems for which the method is applied ranges from N=7-25, where N is the total number of atoms in the cluster. We also test the results obtained by us by comparing with an established gradient only method. Moreover to demonstrate that our strategy can overcome the standard problems of drag method, we apply our strategy to a two dimensional LEPS + harmonic oscillator Potential to locate the TS, in which standard drag method has been seen to encounter problems.
Theory of gas discharge plasma
Smirnov, Boris M
2015-01-01
This book presents the theory of gas discharge plasmas in a didactical way. It explains the processes in gas discharge plasmas. A gas discharge plasma is an ionized gas which is supported by an external electric field. Therefore its parameters are determined by processes in it. The properties of a gas discharge plasma depend on its gas component, types of external fields, their geometry and regimes of gas discharge. Fundamentals of a gas discharge plasma include elementary, radiative and transport processes which are included in its kinetics influence. They are represented in this book together with the analysis of simple gas discharges. These general principles are applied to stationary gas discharge plasmas of helium and argon. The analysis of such plasmas under certain conditions is theoretically determined by numerical plasma parameters for given regimes and conditions.
... problems with gas if you: Are lactose or gluten intolerant Eat a diet rich in fruits, vegetables, whole grains and legumes Drink carbonated beverages Have a chronic intestinal condition, such as irritable bowel syndrome or inflammatory bowel disease Neither age nor sex ...
Institute of Scientific and Technical Information of China (English)
余丽华; 王立勋; 罗红; 叶燕红
2011-01-01
目的:探讨小儿麻醉诱导期家长陪同在笑气-七氟醚序贯吸入模式的应用及护理对策.方法:选择择期手术患儿,随机分为观察组和对照组,观察组为家长陪同下笑气-七氟醚序贯吸入麻醉诱导,对照组则无家长陪同常规麻醉诱导程序,观察两组患儿麻醉诱导前的血压、心率、呼吸、血氧饱和度及情绪变化,通过问卷方式调查两组患儿术后心理行为、家长满意度.结果:对照组患儿麻醉诱导期血压及心率、呼吸显著高于观察组,血氧饱和度低于观察组(P<0.01),观察组术后心理行为明显优于对照组,观察组家长满意度提高.结论:PPIP辅助笑气-七氟醚序贯吸入麻醉诱导患儿安静合作、生命体征稳定,术后心理行为正常,家长满意.%Objective:To explore the application of using sevoflurane and nitrous oxide for gas induction of general anaesthesia and develop nursing care plan.Methods:Paediatric patients undergo elective operation will be selected and divided in two groups:research group, using sevoflurane and nitrous oxide for gas induction of general anaesthesi with parent presence and compare group, using sevoflurane and nitrous oxide for gas induction of general anaesthesia with no parent presence.During the induction period,patient's blood pressure,heart rate, respiration rate, pulse oximetry oxygen saturation and change on behaviour and mood will be monitored for both groups of patients.Questionnaire will be used to investigate the patient's psychological behaviour and satisfaction of the parents in the post - operation visit.Results:The blood pressure, heart rate and respiration rate for the compare group was markedly higher than the research group during the induction period.The blood oxygen saturation for the control group was lower than the research group ( P ＜0.01 ).The patient' s post - operative psychological behaviour and satisfaction of the parent in the research group was better than the
Institute of Scientific and Technical Information of China (English)
徐燕
2014-01-01
目的：探讨全麻下腹腔镜胆囊切除术中胃积气的护理干预措施。方法选取自2012年2月至2014年4月行腹腔镜胆囊切除术患者150例，按照手术先后顺序分为干预组和对照组，对照组采用常规护理方法，干预组在常规护理基础上进行心理护理、麻醉诱导时预给氧及按压腹部等护理干预，以减少术中胃积气的发生。观察两组患者术中胃积气的情况。结果干预组胃积气程度显著小于对照组，两组比较有显著差异（P＜0．05）。结论适当的护理干预措施可以减少腹腔镜胆囊切除术中胃积气的发生，使手术视野能充分暴露，保证手术的顺利完成。%Objective To explore the care interventions of accumulated stomach gas produced in laparoscopiccholecystectomy with general anesthesia .Methods 150 laparoscopiccholecystectomy cases from February 2012 to April 2014 were selected .According to the order of surgeries , those cases were divided into two groups, the intervention and control groups . The control group adopted conventional methods , while the intervention group applied self-psychological care , pre-oxygenation during induction of anesthesia and nursing interventions , such as pressing the abdomen besides the conventional methods , in order to reduce the incidence of accumulated stomach gas produced during the surgeries .The volumes of accumulated stomach gas were recorded in both groups .Results It was found that accumulated stomach gas in the intervention group was significantly less than the control group (P<0.05).Conclusions Appropriate care interventions can reduce the incidence of accumulated stomachgas produced during laparoscopic cholecystectomy , which will lead to fullyoperative field exposure and then ensure the completion of the surgeries .
Luebke, Ryan
2015-01-22
A gas sensor using a metal organic framework material can be fully integrated with related circuitry on a single substrate. In an on-chip application, the gas sensor can result in an area-efficient fully integrated gas sensor solution. In one aspect, a gas sensor can include a first gas sensing region including a first pair of electrodes, and a first gas sensitive material proximate to the first pair of electrodes, wherein the first gas sensitive material includes a first metal organic framework material.
18 CFR 270.101 - General definitions.
2010-04-01
... gas produced from coal seams means naturally occurring natural gas released from entrapment from the fractures, pores and bedding planes of coal seams. (7) Natural gas produced from Devonian shale means... General Definitions § 270.101 General definitions. (a) NGPA definitions. Terms defined in the Natural...
Institute of Scientific and Technical Information of China (English)
张庆兵; 韩苗华; 周懿; 封丽丽; 刘佳; 刘毅
2014-01-01
Objective:To verify the factors associated with gas leakage in applying of streamlined liner of the pharyngeal airway ( SLIPA) with classic la-ryngeal mask airway (LMA) to mechanically ventilated patients in general anesthesia.Methods:260 patients undergone minor surgery with general anes-thesia were included and recorded regarding the gender, ages, body mass index, Mallampati classification, neck circumference, thyromental distance (TMD),mandibular length,width of mouth opening and status of teeth before anesthesia.Selection of the LMA size was complied to the width of thyroid cartilage of patients,and determination of LMA leakage was based on the operator′s experience and tidal volume monitoring.χ2 test was used to analyze the difference concerning the parameters described previously between the leakage group and the non-leakage group.Results:SLIPA LMAs were successfully applied in 254 patients,whereas LMA leakage was found in 17 cases.Higher incidence of the gas leakage was seen patients with shorter TMD (35% vs. 5%) and without teeth (29% vs.3% )when the two groups were compared (P<0.05).Conclusion:SLIPA LMA can be safely used in mechanically ventilated patients under general anesthesia,yet higher incidences of gas leakage may be involved in those with short TMD or without teeth.%目的：筛选全麻机械通气使用SLIPA喉罩时发生漏气的相关因素。方法：选取短小全麻手术260例，记录患者性别、年龄、体质量指数、Mallampati分级、颈围、甲颏距、下颌骨水平长度、张口度以及牙齿情况。根据甲状软骨宽度选取合适型号的喉罩。操作者根据临床经验和潮气量监测判断喉罩是否漏气。采用卡方检验比较喉罩漏气和未漏气两组患者间各项指标的差异。结果：260例患者成功置入SLIPA喉罩，其中17例出现喉罩漏气。与喉罩未漏气患者相比，喉罩漏气患者短颏甲距（35％vs．5％）和无牙（29％vs．3
Direct fired absorption machine flue gas recuperator
Reimann, Robert C.; Root, Richard A.
1985-01-01
A recuperator which recovers heat from a gas, generally the combustion gas of a direct-fired generator of an absorption machine. The recuperator includes a housing with liquid flowing therethrough, the liquid being in direct contact with the combustion gas for increasing the effectiveness of the heat transfer between the gas and the liquid.
A Study of Universal Thermodynamics in Lanczos-Lovelock gravity
Mitra, Saugata; Chakraborty, Subenoy
2016-01-01
A study of Universal thermodynamics is done in Lanczos-Lovelock gravity. The Universe is chosen as FRW model bounded by apparent or event horizon. The unified first law is examined, assuming extended Hawking temperature on the horizon. As a result there is a modification of Bekenstein entropy on the horizons. Further the validity of generalized second law of thermodynamics and thermodynamical equilibrium are also investigated for perfect fluid (with constant equation of state), modified chaplygin gas model and holographic dark energy model.
Bulk viscosity driving the acceleration of the Universe
Fabris, J C; De Ribeiro, R S
2006-01-01
The possibility that the present acceleration of the universe is driven by a kind of viscous fluid is exploited. At background level this model is similar to the generalized Chaplygin gas model (GCGM). But, at perturbative level, the viscous fluid exhibits interesting properties. In particular the oscillations in the power spectrum that plagues the GCGM are not present. Possible fundamental descriptions for this viscous dark energy are discussed.
Gas transport in solid oxide fuel cells
He, Weidong; Dickerson, James
2014-01-01
This book provides a comprehensive overview of contemporary research and emerging measurement technologies associated with gas transport in solid oxide fuel cells. Within these pages, an introduction to the concept of gas diffusion in solid oxide fuel cells is presented. This book also discusses the history and underlying fundamental mechanisms of gas diffusion in solid oxide fuel cells, general theoretical mathematical models for gas diffusion, and traditional and advanced techniques for gas diffusivity measurement.
Requirements for gas quality and gas appliances
Levinsky, Howard; Gersen, Sander; Kiewiet, Bert
2015-01-01
Introduction The gas transmission network in the Netherlands transports two different qualities of gas, low-calorific gas known as G-gas or L-gas and, high calorific gas (H-gas). These two gas qualities are transported in separate networks, and are connected by means of five blending and conversion
Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert
2016-05-03
Measurement of a precessional rate of a gas, such as an alkali gas, in a magnetic field is made by promoting a non-uniform precession of the gas in which substantially no net magnetic field affects the gas during a majority of the precession cycle. This allows sensitive gases that would be subject to spin-exchange collision de-phasing to be effectively used for extremely sensitive measurements in the presence of an environmental magnetic field such as the Earth's magnetic field.
Energy Technology Data Exchange (ETDEWEB)
Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert
2016-05-03
Measurement of a precessional rate of a gas, such as an alkali gas, in a magnetic field is made by promoting a non-uniform precession of the gas in which substantially no net magnetic field affects the gas during a majority of the precession cycle. This allows sensitive gases that would be subject to spin-exchange collision de-phasing to be effectively used for extremely sensitive measurements in the presence of an environmental magnetic field such as the Earth's magnetic field.
Guiochon, Georges; Guillemin, Claude L.
1990-11-01
Gas chromatography is a powerful separation technique for gas and vapor mixtures. Combining separation and on-line detection permits accurate quantitative analysis of complex mixtures, including traces of compounds down to parts per trillions in some particular cases. The importance of gas chromatography in quality control and process control in the chemical and drug industry, in environmental pollution investigations and in clinical analysis is critical. The principles of the technique are discussed, the main components of a gas chromatograph are described and some idea of the importance of the applications is given.
Elizarova, Tatiana G
2009-01-01
This book presents two interconnected mathematical models generalizing the Navier-Stokes system. The models, called the quasi-gas-dynamic and quasi-hydrodynamic equations, are then used as the basis of numerical methods solving gas- and fluid-dynamic problems.
... Some general dentists work in government health services, research programs, higher education, corporations and even the military. ?xml:namespace> What kind of procedures do general dentists provide? ?xml:namespace> Many general dentists are ...
Spherical collapse for unified dark matter models
Caramês, Thiago R P; Velten, Hermano E S
2014-01-01
We study the non-linear spherical "top hat" collapse for Chaplygin and viscous unified cosmologies. The term unified refers to models where dark energy and dark matter are replaced by one single component. For the generalized Chaplygin gas (GCG) we extend previous results of [R. A. A. Fernandes {\\it et al}. Physical Review D 85, 083501 (2012)]. We discuss the differences at non-linear level between the GCG with $\\alpha=0$ and the $\\Lambda$CDM model. We show that both are indeed different. The bulk viscous model which differs from the GCG due to the existence of non-adiabatic perturbations is also studied. In this case, the clustering process is in general suppressed and the viable parameter space of the viscous model that accelerates the background expansion does not lead to collapsed structures. This result challenges the viability of unified viscous models.
基于广义概念的城市燃气管道泄漏精确定位%The Precise Location of City Gas Pipeline Leak Based on the Generalized Concept
Institute of Scientific and Technical Information of China (English)
郝永梅; 徐明; 李秀中; 毛小虎; 严欣明; 岳云飞
2016-01-01
为了准确地检测城市燃气管道泄漏 ,提出了一种基于广义概念的管道泄漏检测定位方法.声发射技术对于管道泄漏的检测、定位是一个极好的工具 ,但由于泄漏源的传播容易受到周围背景噪声以及复杂工况的影响 ,其定位误差较大.基于时延估计的互相关信号处理方法被广泛用于管道泄漏检测定位 ,但由于泄漏应力波传播通道的动态特性 ,使得源信号在传播过程中会产生波形变化 ,给互相关函数峰值位置的确定带来困难.由此引入广义相关分析方法 ,通过对信号进行前置滤波 ,在一定程度上减少了传播通道动态特性因素对泄漏点定位的不利影响 ,得到了更为准确的时延估值.在此基础上 ,通过模拟实验 ,编写Matlab神经网络代码 ,构造GRNN模型 ,进一步预测定位.结果表明 ,GRNN预测的声发射检测值、互相关定位值以及广义相关定位值 ,相比之前定位精度分别得到提高 ,其中基于广义相关的延时估计方法定位最为精确 ,将该方法用于工程实际中 ,可以更加精确地定位出泄漏点.%In order to accurately detect leakage of city gas pipeline ,a method is proposed based on broad concept of leak detection and location of pipeline .Acoustic emission technique is an excellent tool for the pipeline leak detection and loca-tion ,but because the spread of the leak source is susceptible to the surrounding background noise and the impact of complex conditions ,its positioning error is greater .The methods based on delay estimation cross-correlation signal processing are widely used in pipeline leak detection and location ,but due to the dynamic characteristics of leakage stress wave propagation path ,the source signal in the communication process will produce changes in waveform and the peak position to cross-cor-relation function determination difficult .Thus the generalized correlation analysis is introduced .To a certain extent ,the
Liepmann, H W
2001-01-01
The increasing importance of concepts from compressible fluid flow theory for aeronautical applications makes the republication of this first-rate text particularly timely. Intended mainly for aeronautics students, the text will also be helpful to practicing engineers and scientists who work on problems involving the aerodynamics of compressible fluids. Covering the general principles of gas dynamics to provide a working understanding of the essentials of gas flow, the contents of this book form the foundation for a study of the specialized literature and should give the necessary background
Energy Technology Data Exchange (ETDEWEB)
Willumsen, H. (Crone and Koch, Viborg (Denmark))
1990-08-01
In most landfills, the refuse deposit usually has a high content of organic matter consisting of a mixture of household, industrial and garden waste. Immediately after the refuse has been placed in the landfill, aerobic decomposition of the organic waste begins. Once the oxygen has been exhausted, anaerobic decomposition begins. 'Biogas' is produced which has a methane content of approximately 50% and can be used as a fuel. The exploitation of landfill gas for energy purposes was initiated in the USA around 1975 and later in Europe. A landfill gas plant consists of a recovery system and a production system. A recovery system can consist of vertical perforated pipe wells, horizontal perforated pipes or ditches, or membrane covers to collect the generated gas. Under normal conditions it will not be necessary to process the gas except for the removal of water and other impurities (e.g. solid particles) if the gas is to be used in a boiler or engine. In the USA most often only power is produced, whereas in Europe the waste heat is normally exploited, making the plant function as a combined power and heating plant. It is also possible to upgrade the landfill gas to a methane content of nearly 100, after which it can be distributed with natural gas. There are several such plants in the USA. 8 refs., 6 figs., 6 tabs.
Energy Technology Data Exchange (ETDEWEB)
Farahan, E.; Eudaly, J.P.
1978-10-01
This evaluation provides performance and cost data for commercially available simple- and regenerative-cycle gas turbines. Intercooled, reheat, and compound cycles are discussed from theoretical basis only, because actual units are not currently available, except on a special-order basis. Performance characteristics investigated include unit efficiency at full-load and off-design conditions, and at rated capacity. Costs are tabulated for both simple- and regenerative-cycle gas turbines. The output capacity of the gas turbines investigated ranges from 80 to 134,000 hp for simple units and from 12,000 to 50,000 hp for regenerative units.
Digital Repository Service at National Institute of Oceanography (India)
Ramprasad, T.
and the role it plays in the global climate and the future of fuels. Russia, Japan, Nigeria, Peru, Chile, Pakistan, Indonesia, Korea, etc are various countries who are perusing the gas hydrates studies as a future resource for fuel. Indian Initiative..., 1993, Free gas at the base of the gas hydrate zone in the vicinity of the Chile Triple junction: Geology, v. 21, pp. 905-908. Borowski, W.S., C.K. Paull, and U. William, III, 1999, Global and local variations of interstitial sulfate gradients...
... also can be caused by group A streptococcus, Staphylococcus aureus, and Vibrio vulnificus . Clostridium is found nearly everywhere. As the bacteria grow inside the body, it makes gas and harmful substances (toxins) that can damage body tissues, cells, and blood ...
Generalization of Hopf Functional Equation
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
This paper generalizes the Hopf functional equation in order to apply it to a wider class of not necessarily incompressible fluid flows. We start by defining characteristic functionals of the velocity field, the density field and the temperature field of a compressible field. Using the continuity equation, the Navier-Stokes equations and the equation of energy we derive a functional equation governing the motion of an ideal gas flow and a van der Waals gas flow, and then give some general methods of deriving a functional equation governing the motion of any compressible fluid flow. These functional equations can be considered as the generalization of the Hopf functional equation.
Energy Technology Data Exchange (ETDEWEB)
Yoo, Byoung Jae; Jung, Tae Jin; Sunwoo, Don [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)
1996-12-01
Sufficient documents were reviewed to understand solid components of water and gaseous hydrocarbon known as gas hydrates, which represent an important potential energy resource of the future. The review provides us with valuable information on crystal structures, kinetics, origin and distribution of gas hydrates. In addition, the review increased our knowledge of exploration and development methods of gas hydrates. Large amounts of methane, the principal component of natural gas, in the form of solid gas hydrate are found mainly offshore in outer continental margin sediment and, to a lesser extent, in polar regions commonly associated with permafrost. Natural gas hydrates are stable in some environments where the hydrostatic pressure exerted by overlying water column is sufficient for hydrate formation and stability. The required high pressures generally restrict gas hydrate to sediments beneath water of approximately 400 m. Higher sediment temperatures at greater subbottom depths destabilize gas hydrates. Based on the pressure- temperature condition, the outer continental margin of East Sea where water depth is deep enough to form gas hydrate is considered to have high potential of gas hydrate accumulations. (author). 56 refs., tabs., figs.
The lifespan of 3D radial solutions to the non-isentropic relativistic Euler equations
Wei, Changhua
2017-10-01
This paper investigates the lower bound of the lifespan of three-dimensional spherically symmetric solutions to the non-isentropic relativistic Euler equations, when the initial data are prescribed as a small perturbation with compact support to a constant state. Based on the structure of the hyperbolic system, we show the almost global existence of the smooth solutions to Eulerian flows (polytropic gases and generalized Chaplygin gases) with genuinely nonlinear characteristics. While for the Eulerian flows (Chaplygin gas and stiff matter) with mild linearly degenerate characteristics, we show the global existence of the radial solutions, moreover, for the non-strictly hyperbolic system (pressureless perfect fluid) satisfying the mild linearly degenerate condition, we prove the blowup phenomenon of the radial solutions and show that the lifespan of the solutions is of order O(ɛ ^{-1}), where ɛ denotes the width of the perturbation. This work can be seen as a complement of our work (Lei and Wei in Math Ann 367:1363-1401, 2017) for relativistic Chaplygin gas and can also be seen as a generalization of the classical Eulerian fluids (Godin in Arch Ration Mech Anal 177:497-511, 2005, J Math Pures Appl 87:91-117, 2007) to the relativistic Eulerian fluids.
Gas treating absorption theory and practice
Eimer, Dag
2014-01-01
Gas Treating: Absorption Theory and Practice provides an introduction to the treatment of natural gas, synthesis gas and flue gas, addressing why it is necessary and the challenges involved. The book concentrates in particular on the absorption-desorption process and mass transfer coupled with chemical reaction. Following a general introduction to gas treatment, the chemistry of CO2, H2S and amine systems is described, and selected topics from physical chemistry with relevance to gas treating are presented. Thereafter the absorption process is discussed in detail, column hardware is explain
Greco,Salvatore; Mesiar, Radko; Rindone, Fabio
2014-01-01
Aggregation functions on [0,1] with annihilator 0 can be seen as a generalized product on [0,1]. We study the generalized product on the bipolar scale [–1,1], stressing the axiomatic point of view. Based on newly introduced bipolar properties, such as the bipolar increasingness, bipolar unit element, bipolar idempotent element, several kinds of generalized bipolar product are introduced and studied. A special stress is put on bipolar semicopulas, bipolar quasi-copulas and bipolar copulas.
Greco, Salvatore; Mesiar, Radko; Rindone, Fabio
2014-01-01
Aggregation functions on [0,1] with annihilator 0 can be seen as a generalized product on [0,1]. We study the generalized product on the bipolar scale [–1,1], stressing the axiomatic point of view. Based on newly introduced bipolar properties, such as the bipolar increasingness, bipolar unit element, bipolar idempotent element, several kinds of generalized bipolar product are introduced and studied. A special stress is put on bipolar semicopulas, bipolar quasi-copulas and bipolar copulas.
Energy Technology Data Exchange (ETDEWEB)
Carayon, B.
2004-06-01
The aim of this report is to present to the French deputies the advice of the commission of finances and economy about the law project relative to the change of status of the power and gas public utilities in the framework of the deregulation of European energy markets. This law changes the juridical status of the two state monopolies Electricite de France (EdF) and Gaz de France (GdF) into two anonymous companies and creates two additional companies for the management of the power and gas networks. It ensures also the transposition of the European directives from June 26, 2003 (2003/54/CE and 2003/55/CE). It contains some proper dispositions and modifies various existing French laws, in particular the law no. 46-628 from April 8, 1946 about the electricity and gas nationalization and the law no. 2000-108 from February 10, 2000 relative to the modernization and development of the electric public utility. The first part of the document reports on the general discussions and comments made by the commission about the law project while the second part concerns the detailed analysis of the articles 16 and 22 about the pension funds of EdF and GdF agents and the change of the status of both utilities. The amendments adopted by the commission for these articles conclude the report. (J.S.)
Nyasulu, Frazier; Barlag, Rebecca
2010-01-01
The reaction kinetics of the iodide-catalyzed decomposition of [subscript 2]O[subscript 2] using the integrated-rate method is described. The method is based on the measurement of the total gas pressure using a datalogger and pressure sensor. This is a modification of a previously reported experiment based on the initial-rate approach. (Contains 2…
Isentropic Spheres in General Relativity
Humi, Mayer
2016-01-01
Astrophysical gas clouds undergo thermodynamically irreversible processes and emit heat to their surroundings. Due the emission of this heat one can envision an idealized situation in which gas entropy remains (almost) constant. With this motivation in mind we derive in this paper interior solutions to the Einstein equations of General Relativity for spheres which consist of isentropic gas. In particular we investigate solutions in which the mass distribution inside the sphere has several shells. Such spheres might be considered an early stage for the formation of a "solar system".
Schmid, Andreas K.; Mascaraque, Arantzazu; Santos, Benito; de la Figuera, Juan
2014-09-09
A gas sensor is described which incorporates a sensor stack comprising a first film layer of a ferromagnetic material, a spacer layer, and a second film layer of the ferromagnetic material. The first film layer is fabricated so that it exhibits a dependence of its magnetic anisotropy direction on the presence of a gas, That is, the orientation of the easy axis of magnetization will flip from out-of-plane to in-plane when the gas to be detected is present in sufficient concentration. By monitoring the change in resistance of the sensor stack when the orientation of the first layer's magnetization changes, and correlating that change with temperature one can determine both the identity and relative concentration of the detected gas. In one embodiment the stack sensor comprises a top ferromagnetic layer two mono layers thick of cobalt deposited upon a spacer layer of ruthenium, which in turn has a second layer of cobalt disposed on its other side, this second cobalt layer in contact with a programmable heater chip.
Chemical kinetics of gas reactions
Kondrat'Ev, V N
2013-01-01
Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema
Natural gas pipeline technology overview.
Energy Technology Data Exchange (ETDEWEB)
Folga, S. M.; Decision and Information Sciences
2007-11-01
transmission companies. Compressor stations at required distances boost the pressure that is lost through friction as the gas moves through the steel pipes (EPA 2000). The natural gas system is generally described in terms of production, processing and purification, transmission and storage, and distribution (NaturalGas.org 2004b). Figure 1.1-2 shows a schematic of the system through transmission. This report focuses on the transmission pipeline, compressor stations, and city gates.
49 CFR 192.11 - Petroleum gas systems.
2010-10-01
... 49 Transportation 3 2010-10-01 2010-10-01 false Petroleum gas systems. 192.11 Section 192.11... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS General § 192.11 Petroleum gas systems. (a) Each plant that supplies petroleum gas by pipeline to a natural gas distribution system must meet the requirements...
46 CFR 181.410 - Fixed gas fire extinguishing systems.
2010-10-01
... 46 Shipping 7 2010-10-01 2010-10-01 false Fixed gas fire extinguishing systems. 181.410 Section... Fixed gas fire extinguishing systems. (a) General. (1) A fixed gas fire extinguishing system aboard a... approved for the system by the Commandant. (4) A fixed gas fire extinguishing system may protect more...
Energy Technology Data Exchange (ETDEWEB)
Michaels, Sascha; Kohler, Desiree M. [Kanzlei Becker Buettner Held, Berlin und Koeln (Germany). Energie- und Infrastrukturrecht
2012-02-15
On 21th December 2011, the European Commission published its proposal for a directive on issuing concessions. With this, a regulatory gap is to be closed which implicated serious distortions of the internal market according to the view of the European Commission. The authors of the contribution under consideration deal with the possible impacts of the planned new regulatory framework on the allocation of concessions of electricity and natural gas.
Tomás Correa; Nelson Osorio
2009-01-01
This paper reviews the present and future on natural gas transportation options, from oil and gas fields to markets, including liquefied natural gas, gas pipeline, compressed natural gas, natural gas hydrates, and gas to liquids and the perspectives of using them in Colombia, since this is the main fuel alternative to supply the world in at least the next 50 years.
Directory of Open Access Journals (Sweden)
Tomás Correa
2009-06-01
Full Text Available This paper reviews the present and future on natural gas transportation options, from oil and gas fields to markets, including liquefied natural gas, gas pipeline, compressed natural gas, natural gas hydrates, and gas to liquids and the perspectives of using them in Colombia, since this is the main fuel alternative to supply the world in at least the next 50 years.
Energy Technology Data Exchange (ETDEWEB)
Hilgers, Claudia
2011-06-17
Sixty years ago, wood gas was even used as a car fuel. Today, this ancient technology is experiencing a renaissance. Small cogeneration plants with wood gasifiers are ideal for renewable and decentral power supply concepts for tomorrow. Until then, there is much pioneering work to do until plants will be ready for serial production.
The General Conformity requirements ensure that the actions taken by federal agencies in nonattainment and maintenance areas do not interfere with a state’s plans to meet national standards for air quality.
... unconscious and unable to feel pain during medical procedures. General anesthesia usually uses a combination of intravenous drugs ... 1998-2017 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved.
Natural gas 1995: Issues and trends
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-11-01
Natural Gas 1995: Issues and Trends addresses current issues affecting the natural gas industry and markets. Highlights of recent trends include: Natural gas wellhead prices generally declined throughout 1994 and for 1995 averages 22% below the year-earlier level; Seasonal patterns of natural gas production and wellhead prices have been significantly reduced during the past three year; Natural gas production rose 15% from 1985 through 1994, reaching 18.8 trillion cubic feet; Increasing amounts of natural gas have been imported; Since 1985, lower costs of producing and transporting natural gas have benefitted consumers; Consumers may see additional benefits as States examine regulatory changes aimed at increasing efficiency; and, The electric industry is being restructured in a fashion similar to the recent restructuring of the natural gas industry.
McGee, Kenneth A.; Gerlach, Terrance M.
1995-01-01
In Roman mythology, Vulcan, the god of fire, was said to have made tools and weapons for the other gods in his workshop at Olympus. Throughout history, volcanoes have frequently been identified with Vulcan and other mythological figures. Scientists now know that the “smoke" from volcanoes, once attributed by poets to be from Vulcan’s forge, is actually volcanic gas naturally released from both active and many inactive volcanoes. The molten rock, or magma, that lies beneath volcanoes and fuels eruptions, contains abundant gases that are released to the surface before, during, and after eruptions. These gases range from relatively benign low-temperature steam to thick hot clouds of choking sulfurous fume jetting from the earth. Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. Other volcanic gases are hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The concentrations of these gas species can vary considerably from one volcano to the next.
Van Maldeghem, Hendrik
1998-01-01
Generalized Polygons is the first book to cover, in a coherent manner, the theory of polygons from scratch. In particular, it fills elementary gaps in the literature and gives an up-to-date account of current research in this area, including most proofs, which are often unified and streamlined in comparison to the versions generally known. Generalized Polygons will be welcomed both by the student seeking an introduction to the subject as well as the researcher who will value the work as a reference. In particular, it will be of great value for specialists working in the field of generalized polygons (which are, incidentally, the rank 2 Tits-buildings) or in fields directly related to Tits-buildings, incidence geometry and finite geometry. The approach taken in the book is of geometric nature, but algebraic results are included and proven (in a geometric way!). A noteworthy feature is that the book unifies and generalizes notions, definitions and results that exist for quadrangles, hexagons, octagons - in the ...
Institute of Scientific and Technical Information of China (English)
Wang Keyu
2001-01-01
@@ PetroChina has recently opened 18 new oil and gas blocks to foreign companies for exploration and development and will soon hold a series of bilateral negotiations on the cooperation projects. Those blocks are located in the northern part of Ordos basin, the northeastern part of Songliao basin, the northwestern part of Caidamu basin and Junggar basin. No blocks in Tarim basin are included in the 18ones. This is the first time for China to offer so many blocks for foreign cooperation on the Chinese soil at one time.
Generalized derivations and general relativity
Heller, M; Pysiak, L; Sasin, W
2013-01-01
We construct differential geometry (connection, curvature, etc.) based on generalized derivations of an algebra A. Such a derivation, introduced by Bresar in 1991, is given by a linear mapping u: A -> A such that there exists a usual derivation d of A satisfying the generalized Leibniz rule u(a b) = u(a) b + a d(b) for all a,b in A. The generalized geometry "is tested" in the case of the algebra of smooth functions on a manifold. We then apply this machinery to study the generalized general relativity. We define the Einstein-Hilbert action and deduce from it Einstein's field equations. We show that for a special class of metrics containing, besides the usual metric components, only one non-zero term, the action reduces to O'Hanlon action that is a Brans-Dicke action with potential and with the parameter \\omega equal to zero. We also show that the generalized Einstein equations (with zero energy-stress tensor) are equivalent to those of the Kaluza-Klein theory satisfying a "modified cylinder condition" and hav...
Directory of Open Access Journals (Sweden)
Monique Florenzano
2008-09-01
Full Text Available General equilibrium is a central concept of economic theory. Unlike partial equilibrium analysis which study the equilibrium of a particular market under the clause “ceteris paribus” that revenues and prices on the other markets stay approximately unaffected, the ambition of a general equilibrium model is to analyze the simultaneous equilibrium in all markets of a competitive economy. Definition of the abstract model, some of its basic results and insights are presented. The important issues of uniqueness and local uniqueness of equilibrium are sketched; they are the condition for a predictive power of the theory and its ability to allow for statics comparisons. Finally, we review the main extensions of the general equilibrium model. Besides the natural extensions to infinitely many commodities and to a continuum of agents, some examples show how economic theory can accommodate the main ideas in order to study some contexts which were not thought of by the initial model
Canuto, V
2015-01-01
This is an English translation of the Italian version of an encyclopedia chapter that appeared in the Italian Encyclopedia of the Physical Sciences, edited by Bruno Bertotti (1994). Following requests from colleagues we have decided to make it available to a more general readership. We present the motivation for constructing General Relativity, provide a short discussion of tensor algebra, and follow the set up of Einstein equations. We discuss briefly the initial value problem, the linear approximation and how should non gravitational physics be described in curved spacetime.
Nonconventional natural gas resources
Energy Technology Data Exchange (ETDEWEB)
None
1979-03-01
It is concluded that it is impossible at this time to forecast the volume of natural gas dissolved in water that can be economically recovered. The investigation to southern Louisiana, both onshore and offshore was confined. Estimates of the dissolved methane content are based upon information on temperatures, pressures, sandstone thicknesses, sandstone porosities, salinity, and the solubility of methane. The salinity of waters encountered in wells was estimated from wireline logs, and in turn used to reduce the estimated content of dissolved gas. The reductions range from 51 to 61 percent of the solubility of methane in fresh water. The assessment does not include gas dissolved in water contained in shale beds. A series of maps display the information used in the computation. Methane solubility values were multiplied by porosity--feet values for each 1000-foot interval. The total dissolved methane in the resource base is estimated to be 6,143 trillion cubic feet (Tcf); assumptions on the effect of salinity reduce this to 3,264 Tcf. This figure does not include methane beneath the Texas coast. Very preliminary estimates of the recoverable proportion of dissolved gas in the highly ''geopressured'' zones range from 1 to over 20 percent. Not all of the resource base estimates of 3,264 Tcf occurs in the highly geopressured zone, and the proportions individually allocatable within the resource base to the highly ''geopressured'' zone, to the intermediate-pressure zone, and to the normal or ''hydropressure'' zone cannotbe estimated readily. The environmental aspects of recovery of dissolved gas are also presented. The review is necessarily generalized, since it could not be based on actual experience. The problems include subsidence of land surface and possibly increased seismic activity. Fluid withdrawal might result in subsidence of the land surface, as well as activation of growth faults, with adjustments
Institute of Scientific and Technical Information of China (English)
2011-01-01
<正>20110727 Dai Deqiu (Institute of Geology, Hunan University of Science and Technology, Xiangtan 411201, China); Wang Daode The Evolvement Models and Progress of Research on Formation of Ca-,Al-Rich inclusions in Chondrites (Geological Review, ISSN0371-5736, CN11-1952/P, 56(3), 2010, p.374-383, 2 illus., 1 table, 72 refs.)Key words: chondrites Ca-, Al-rich inclusions (CAIs) are the earliest assemblages formed in the solar nebula. The formation models of CAIs include gas-soild condensation, crystallization from melting or partial melting and high-temperature evaporating residues. The latest study shows similar distribution patterns of the petrographic types and sizes of CAIs in various chondrites. The petrographic characters argue that CAIs in various chemical groups of chondrites formed under similar processes and conditions probably in a same region in the solar nebula.
Yershov, Edward D.; Williams, Peter J.
2004-08-01
In the cold regions, freezing of the ground presents major geotechnical and environmental challenges. In Russia, oil and gas gives these regions special economic and geopolitical significance. After glasnost, it became evident that research there was more comprehensive but the problems far greater than elsewhere. This translation of a wide-ranging account of the effects of freezing and their importance for geotechnical undertakings, has been prepared by an international team of specialists. It makes available a uniquely readable and technically accurate review, especially valuable to international organisations and those involved in joint ventures. The English edition of the 16-sheet geocryological map of Russian has been prepared by the same international team. For more details please see: www.freezingground.org/map or contact Scott Polar Research Institute, (Attn. Prof. P. J. Williams), Lensfield Rd., Cambridge, CB2 1ER, UK. - or e-mail: pjw1005@cus.cam.ac.uk.
U.S. Geological Survey, Department of the Interior — Regions of high or low potential for oil and gas resources in the Powder River Basin generally indicate where continuous oil and gas resources are more or less...
Staff Association
2016-01-01
5th April, 2016 – Ordinary General Assembly of the Staff Association! In the first semester of each year, the Staff Association (SA) invites its members to attend and participate in the Ordinary General Assembly (OGA). This year the OGA will be held on Tuesday, April 5th 2016 from 11:00 to 12:00 in BE Auditorium, Meyrin (6-2-024). During the Ordinary General Assembly, the activity and financial reports of the SA are presented and submitted for approval to the members. This is the occasion to get a global view on the activities of the SA, its financial management, and an opportunity to express one’s opinion, including taking part in the votes. Other points are listed on the agenda, as proposed by the Staff Council. Who can vote? Only “ordinary” members (MPE) of the SA can vote. Associated members (MPA) of the SA and/or affiliated pensioners have a right to vote on those topics that are of direct interest to them. Who can give his/her opinion? The Ordinary General Asse...
Joseph, Dan; Hartman, Gregory; Gibson, Caleb
2011-01-01
In this article we explore the consequences of modifying the common definition of a parabola by considering the locus of all points equidistant from a focus and (not necessarily linear) directrix. The resulting derived curves, which we call "generalized parabolas," are often quite beautiful and possess many interesting properties. We show that…
Jagers op Akkerhuis, Gerard A.J.M.
2016-01-01
The general discussion focuses on some aspects that are of overarching relevance for all the preceding chapters. The fi rst subject that is discussed is the relationship between systems theory and the philosophy of science. After a short summary of the principles of system science and the
1949-01-01
In part I of this study a survey has veen given of what Dutch authors have written since 1870, when capital punishment was abolished, on subjects concerning the general preventive effect of punishment. This historical survey ends where, during the years 1940-1945, under the stress of the occupation
Showstack, Randy
When poisonous hydrogen sulfide contaminates a natural gas deposit, the drilling company usually caps the well and moves on to other areas that may contain larger reserves and offer stronger economic incentives. Chemical and biological methods exist to purify these wells, but most are complex and costly. However, a group of scientists now is developing what could be a cheaper, easier method to clean up and utilize this polluted natural gas.The technique—which involves growing “enrichment” cultures of bacteria that metabolize the hydrogen sulfide into harmless compounds—could be particularly useful to poor and energy-starved developing nations, says Norman Wainwright, a senior scientist at the Woods Hole Marine Biological Laboratory. “We're hoping the technique can be robust enough and inexpensive enough to be used in a developing country,” Wainwright says. Other scientists involved with the project are Porter Anderson, a University of Rochester professor emeritus associated with the lab and Ben Ebenhack, also of Rochester.
2010-01-01
... AGRICULTURE ESSENTIAL AGRICULTURAL USES AND VOLUMETRIC REQUIREMENTS-NATURAL GAS POLICY ACT § 2900.1 General... percentages of use, of persons, or classes thereof, for essential agricultural uses in order to meet... essential agricultural uses whose natural gas supplies are distributed through the interstate...
2010-10-01
... sounds on low oil pressure and high cooling water temperature. (i) If the prime mover is a gas turbine... Emergency Diesel and Gas Turbine Engine Driven Generator Sets § 112.50-1 General. (a) The prime mover of a... thermostatically-controlled electric water-jacket heater connected to the final emergency bus is permitted. (e)...
Vymetal, J
2003-01-01
Nowadays a theoretical psychotherapeutical thinking develops from the eclectic practice and uses particularly the research of the effective factors of the therapy. Best they can be characterized as differentiate, synthetic, integrative and exceeding other approaches. The development in question goes on with attempts of creating a general model of the psychotherapy that could be a basis for models of special psychotherapies. The aim of such a model is to describe all that is present as important factor for inducing a desirable change of a human in all psychotherapeutical approaches. Among general models we can mention the generic model of D. E. Orlinski and K. I. Howard, Grawe's cube (the author is K. Grawe) and the equation of the psychotherapy.
Maldeghem, Hendrik
1998-01-01
This book is intended to be an introduction to the fascinating theory ofgeneralized polygons for both the graduate student and the specialized researcher in the field. It gathers together a lot of basic properties (some of which are usually referred to in research papers as belonging to folklore) and very recent and sometimes deep results. I have chosen a fairly strict geometrical approach, which requires some knowledge of basic projective geometry. Yet, it enables one to prove some typically group-theoretical results such as the determination of the automorphism groups of certain Moufang polygons. As such, some basic group-theoretical knowledge is required of the reader. The notion of a generalized polygon is a relatively recent one. But it is one of the most important concepts in incidence geometry. Generalized polygons are the building bricks of Tits buildings. They are the prototypes and precursors of more general geometries such as partial geometries, partial quadrangles, semi-partial ge ometries, near...
Sensor platform for gas composition measurement
De Graaf, G.; Bakker, F.; Wolffenbuttel, R.F.
2011-01-01
The gas sensor research presented here has a focus on the measurement of the composition of natural gas and gases from sustainable resources, such as biogas. For efficient and safe combustion, new sensor systems need to be developed to measure the composition of these new gases. In general about 6 g
Institute of Scientific and Technical Information of China (English)
赵念峰; 杨建香; 刘功俭
2008-01-01
Objective To evaluate the effects of general anesthesia combined with throacic epidural block on pulmonary gas ex-change during one-lung ventilation in patients undergoing thoracic surgery. Methods Eighty patients of ASA Ⅰ-Ⅱ undergoing electivethroacic surgery were randomly divided into two Groups (n = 40 ) receiving combined genera] anesthesia with throacic epidural block(group A ) or general anesthesia (group B ). MAP, HR, SpO2, PETCO2, VT, Paw were monitored at both bronps. Arterial andmixed vein blood gas were analyzed and Qs/Qt ,A-aDO2,Vd/Vt were calculated in both groups at 20 rain ( T1 ) before one-lung ventila-tion and 30 min( T2 ), 60 min( T3 ), as well as 120 min ( T4 ) after one-lung ventilation. Results In both groups, Paw and Qs/Qt in-creased while PaO2 decreased significantly at T2-4, ( P0.05);与B组相比,A组T2-4时的Qs/Qt增加(P0.05).结论 单肺通气期间硬膜外阻滞复合全麻对肺换气功能有影响,使Qs/Qt增加,PaO2下降,A-aDO2增大;对肺泡通气功能指标Vd/Vt影响甚微.
Indian National Gas Hydrate Program Expedition 01 report
Collett, Timothy S.; Riedel, M.; Boswell, R.; Presley, J.; Kumar, P.; Sathe, A.; Sethi, A.; Lall, M.; ,
2015-01-01
Gas hydrate is a naturally occurring “ice-like” combination of natural gas and water that has the potential to serve as an immense resource of natural gas from the world’s oceans and polar regions. However, gas-hydrate recovery is both a scientific and a technical challenge and much remains to be learned about the geologic, engineering, and economic factors controlling the ultimate energy resource potential of gas hydrate. The amount of natural gas contained in the world’s gas-hydrate accumulations is enormous, but these estimates are speculative and range over three orders of magnitude from about 2,800 to 8,000,000 trillion cubic meters of gas. By comparison, conventional natural gas accumulations (reserves and undiscovered, technically recoverable resources) for the world are estimated at approximately 440 trillion cubic meters. Gas recovery from gas hydrate is hindered because the gas is in a solid form and because gas hydrate commonly occurs in remote Arctic and deep marine environments. Proposed methods of gas recovery from gas hydrate generally deal with disassociating or “melting” in situ gas hydrate by heating the reservoir beyond the temperature of gas-hydrate formation, or decreasing the reservoir pressure below hydrate equilibrium. The pace of energy-related gas hydrate assessment projects has accelerated over the past several years.
Institute of Scientific and Technical Information of China (English)
王键; 朱彤; 王俩; 杨剑; 宋宝华; 王中原; 周欣; 王瑾
2012-01-01
以600 MW火电机组现有SCR脱硝装置为研究对象,应用CFD软件完成建立模型、划分网格、选择数学模型、设置边界条件、模拟计算等工作,最终得出SCR脱硝系统流速分布及Cv值、压力损失、NH3分布及逃逸浓度等结果。结果表明：SCR脱硝系统流速分布均匀、偏差符合设计要求,NH3与烟气混合均匀,氨逃逸浓度低。%Taking SCR deNOx installations for 600MW thermoelectric generating set as study object,CFD software was used to complete the building models,division of grid,choosing the mathematical model,setting boundary conditions,and simulation work;at last it was obtained the results of SCR deNOx system velocity distribution and Cv value,pressure loss,distribution and escaping concentration of NH3.Results indicated that SCR deNOx system velocity was distributed evenly and the deviations in line could meet design requirements,NH3 was mixed with flue gas evenly,ammonia escaping concentration was low.
Discussion of gas enrichment mechanism and natural gas origin in marine sedimentary basin, China
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
There are abundant natural gas resources in Chinese marine sedimentary basin. The exploration hot shots of natural gas are the Palaeozoic marine strata here in recent years, and several large scale gas fields have been discovered. Chinese Palaeozoic high-post matured and coal measure hydrocarbon source rocks are mainly prone to gas generation in the present. This research considered that gas source rocks and TSR are the key cause of gas enrichment of marine strata. High-quality argillaceous and coal measure hydrocarbon rocks are distributed widely in the Palaeozoic marine strata, which have been in highly matured phase in the present. The argillaceous source rock generally contains various sulfates that could accelerate crude oil cracking to gas for TSR occurrence, and coal measure source rock mainly generates gas, so Chinese marine basin gives priority to accumulating gas. Marine strata have not founded oil reservoirs in the Sichuan Basin and Ordos Basin, and they consist mainly of dry gas. Marine natural gases are the mixed gases of oil cracking gas and coal-formed gas in a general way,oil cracking gases contain usually some H2S and CO2. Hydrocarbon carbon isotopes are very complicated, and methane and ethane isotopic values bear apparent reversal caused by thermal evolution and mixing among different genetic types of natural gas. Coal-formed gases are the main component of Chinese marine natural gas. The Upper Permian of the Sichuan Basin and the Carboniferous-Permian of the Ordos Basin coal measure hydrocarbon source rock present large hydrocarbon generation potential, which are the prospecting highlight of marine natural gas hereafter. Oil cracking gas exploration will be paid much attention to in the Tarim Basin because of the lack of coal measure hydrocarbon source rock.
Khriplovich, I. B
2005-01-01
This book offers an alternative to other textbooks on the subject, providing a more specific discussion of numerous general relativistic effects for readers who have knowledge of classical mechanics and electrodynamics, including special relativity. Coverage includes gravitational lensing, signal retardation in the gravitational field of the Sun, the Reissner-Nordström solution, selected spin effects, the resonance transformation of an electromagnetic wave into a gravitational one, and the entropy and temperature of black holes. The book includes numerous problems at various levels of difficulty, making it ideal also for independent study by a broad readership of advanced students and researchers. I.B. Khriplovich is Chief Researcher, Budker Institute of Nuclear Physics, Novosibirsk, and Chair of Theoretical Physics at Novosibirsk University. Dr. Khriplovich is a Corresponding Member of the Russian Academy of Sciences. He has been awarded the Dirac Medal ``For the advancement of theoretical physics'' by Univ...
Feiss, P
2001-04-30
General anaesthesia is a reversible loss of consciousness induced and maintained with a hypnotic drug given either by venous injection and infusion, or by inhalation. A potent opioid is usually associated to inhibit the transmission of pain and thus to lessen sympathetic and endocrine reactions to nociceptive stimuli. Myorelaxation is used to facilitate tracheal intubation and surgery. Whatever the anaesthetic protocol use, the patient and anaesthesia machine require close monitoring. In addition to vital signs, the depth of anaesthesia may be monitored using automated electroencephalographic analysis and myorelaxation should always be monitored using a nerve stimulator, but pain or analgesia evaluation is only based on clinical signs of sympathetic stimulation. Because anaesthesia-related death and morbidity have decreased considerably, future improvements in outcome should concern perioperative comfort, i.e. prevention of cognitive disturbances, nausea, vomiting and pain.
Qian, Michael C.
Gas chromatography (GC) has many applications in the analysis of food products. GC has been used for the determination of fatty acids, triglycerides, cholesterol, gases, water, alcohols, pesticides, flavor compounds, and many more. While GC has been used for other food components such as sugars, oligosaccharides, amino acids, peptides, and vitamins, these substances are more suited to analysis by high performance liquid chromatography. GC is ideally suited to the analysis of volatile substances that are thermally stable. Substances such as pesticides and flavor compounds that meet these criteria can be isolated from a food and directly injected into the GC. For compounds that are thermally unstable, too low in volatility, or yield poor chromatographic separation due to polarity, a derivatization step must be done before GC analysis. The two parts of the experiment described here include the analysis of alcohols that requires no derivatization step, and the analysis of fatty acids which requires derivatization. The experiments specify the use of capillary columns, but the first experiment includes conditions for a packed column.
Low-temperature gas from marine shales
Directory of Open Access Journals (Sweden)
Jarvie Daniel M
2009-02-01
Full Text Available Abstract Thermal cracking of kerogens and bitumens is widely accepted as the major source of natural gas (thermal gas. Decomposition is believed to occur at high temperatures, between 100 and 200°C in the subsurface and generally above 300°C in the laboratory. Although there are examples of gas deposits possibly generated at lower temperatures, and reports of gas generation over long periods of time at 100°C, robust gas generation below 100°C under ordinary laboratory conditions is unprecedented. Here we report gas generation under anoxic helium flow at temperatures 300° below thermal cracking temperatures. Gas is generated discontinuously, in distinct aperiodic episodes of near equal intensity. In one three-hour episode at 50°C, six percent of the hydrocarbons (kerogen & bitumen in a Mississippian marine shale decomposed to gas (C1–C5. The same shale generated 72% less gas with helium flow containing 10 ppm O2 and the two gases were compositionally distinct. In sequential isothermal heating cycles (~1 hour, nearly five times more gas was generated at 50°C (57.4 μg C1–C5/g rock than at 350°C by thermal cracking (12 μg C1–C5/g rock. The position that natural gas forms only at high temperatures over geologic time is based largely on pyrolysis experiments under oxic conditions and temperatures where low-temperature gas generation could be suppressed. Our results indicate two paths to gas, a high-temperature thermal path, and a low-temperature catalytic path proceeding 300° below the thermal path. It redefines the time-temperature dimensions of gas habitats and opens the possibility of gas generation at subsurface temperatures previously thought impossible.
Gas sensor protection device and method
Boyd, David; Magera, Craig
2016-11-08
A gas sensor includes a sensor housing and a sensing element located within the sensor housing. The sensing element has a distal end and defines an axis. The gas sensor also includes a sensor protection device coupled to the sensor housing and at least partially surrounding the distal end of the sensing element. The sensor protection device includes a first member coupled to the housing, the first member having a generally rectangular cross-sectional shape in a plane perpendicular to the axis. The first member includes a gas inlet and a gas outlet. The sensor protection device also includes a second member coupled to the housing.
Gas-Water Flow Behavior in Water-Bearing Tight Gas Reservoirs
Directory of Open Access Journals (Sweden)
Renyi Cao
2017-01-01
Full Text Available Some tight sandstone gas reservoirs contain mobile water, and the mobile water generally has a significant impact on the gas flowing in tight pores. The flow behavior of gas and water in tight pores is different than in conventional formations, yet there is a lack of adequate models to predict the gas production and describe the gas-water flow behaviors in water-bearing tight gas reservoirs. Based on the experimental results, this paper presents mathematical models to describe flow behaviors of gas and water in tight gas formations; the threshold pressure gradient, stress sensitivity, and relative permeability are all considered in our models. A numerical simulator using these models has been developed to improve the flow simulation accuracy for water-bearing tight gas reservoirs. The results show that the effect of stress sensitivity becomes larger as water saturation increases, leading to a fast decline of gas production; in addition, the nonlinear flow of gas phase is aggravated with the increase of water saturation and the decrease of permeability. The gas recovery decreases when the threshold pressure gradient (TPG and stress sensitivity are taken into account. Therefore, a reasonable drawdown pressure should be set to minimize the damage of nonlinear factors to gas recovery.
Energy Technology Data Exchange (ETDEWEB)
NONE
2008-04-15
The generic environmental impact assessment (EIA or MER in Dutch) in 1999 is intended to serve as a template for specific environmental impact assessments for oil and gas exploitation projects at sea. Since 1999, a number of innovations and changes were implemented. Particularly in offshore technologies and regulations new insights and ideas came up in recent years. Therefore the existing generic document has to be updated with new information, relevant in the preparation of specific environmental impact assessments in the offshore oil and gas exploitation industry in the Dutch part of the Continental Shelf [Dutch] De generieke milieu effect rapportage (MER) uit 1999 is bedoeld om te dienen als een sjabloon voor specifieke Milieueffectrapportages bij olie- en gaswinningprojecten op zee. Sinds 1999 is een aantal vernieuwingen en veranderingen doorgevoerd. Met name in offshore technologieen en wet- en regelgeving zijn de afgelopen jaren nieuwe inzichten en ideeen ontstaan. Hierdoor is de wens ontstaan om het bestaande generieke document aan te vullen met nieuwe informatie die relevant is voor het opstellen van specifieke Milieueffectrapportages in de offshore olie- en gaswinningsindustrie op het Nederlands deel van het Continentaal Plat.
Energy Technology Data Exchange (ETDEWEB)
NONE
2008-04-15
The generic environmental impact assessment (EIA or MER in Dutch) in 1999 is intended to serve as a template for specific environmental impact assessments for oil and gas exploitation projects at sea. Since 1999, a number of innovations and changes were implemented. Particularly in offshore technologies and regulations new insights and ideas came up in recent years. Therefore the existing generic document has to be updated with new information, relevant in the preparation of specific environmental impact assessments in the offshore oil and gas exploitation industry in the Dutch part of the Continental Shelf [Dutch] De generieke milieu effect rapportage (MER) uit 1999 is bedoeld om te dienen als een sjabloon voor specifieke Milieueffectrapportages bij olie- en gaswinningprojecten op zee. Sinds 1999 is een aantal vernieuwingen en veranderingen doorgevoerd. Met name in offshore technologieen en wet- en regelgeving zijn de afgelopen jaren nieuwe inzichten en ideeen ontstaan. Hierdoor is de wens ontstaan om het bestaande generieke document aan te vullen met nieuwe informatie die relevant is voor het opstellen van specifieke Milieueffectrapportages in de offshore olie- en gaswinningsindustrie op het Nederlands deel van het Continentaal Plat.
Accelerated Gas Carburizing (URX Gas Carburizing)
Institute of Scientific and Technical Information of China (English)
Yoshikazu Shimosato; Mamoru Kamitani; Hiroyuki Nakatsu
2004-01-01
URX gas carburizing is an accelerated gas carburizing method with 50% CO + 50% H2 gas which comes from CH4 gas + CO2 gas. By using this gas composition, the carburizing reaction rate increases to the maximum and the controllability of carbon potential improves. A carbon mass flow rate is the product of the carburizing reaction rate multiplied by the difference of carbon percent between carbon potential of the gas and the carbon content of the surface of treated steel parts. We have obtained excellent results from the experimental tests at our laboratory as mentioned bellow. 1)Carburizing time can be shortened by 40% for 0.5 - 0.9 mm effective case depth. 2) Uniform carburizing case depth 3) Less internal oxidation with the same case depth. We have already developed the new roller hearth type continuous carburizing furnace and the new URX gas generator.
46 CFR 197.328 - PVHO-General.
2010-10-01
... GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.328 PVHO—General. (a) Each PVHO... controls; (17) Have a speech unscrambler when used with mixed-gas; (18) Have interior electrical...
Noble gas fractionation during subsurface gas migration
Sathaye, Kiran J.; Larson, Toti E.; Hesse, Marc A.
2016-09-01
Environmental monitoring of shale gas production and geological carbon dioxide (CO2) storage requires identification of subsurface gas sources. Noble gases provide a powerful tool to distinguish different sources if the modifications of the gas composition during transport can be accounted for. Despite the recognition of compositional changes due to gas migration in the subsurface, the interpretation of geochemical data relies largely on zero-dimensional mixing and fractionation models. Here we present two-phase flow column experiments that demonstrate these changes. Water containing a dissolved noble gas is displaced by gas comprised of CO2 and argon. We observe a characteristic pattern of initial co-enrichment of noble gases from both phases in banks at the gas front, followed by a depletion of the dissolved noble gas. The enrichment of the co-injected noble gas is due to the dissolution of the more soluble major gas component, while the enrichment of the dissolved noble gas is due to stripping from the groundwater. These processes amount to chromatographic separations that occur during two-phase flow and can be predicted by the theory of gas injection. This theory provides a mechanistic basis for noble gas fractionation during gas migration and improves our ability to identify subsurface gas sources after post-genetic modification. Finally, we show that compositional changes due to two-phase flow can qualitatively explain the spatial compositional trends observed within the Bravo Dome natural CO2 reservoir and some regional compositional trends observed in drinking water wells overlying the Marcellus and Barnett shale regions. In both cases, only the migration of a gas with constant source composition is required, rather than multi-stage mixing and fractionation models previously proposed.
Directory of Open Access Journals (Sweden)
Antoce Arina Oana
2017-01-01
Full Text Available The present work aimed to determine some of the influences of the treatments with glutathione (GSH, ascorbic acid (AA, catechinic tannin (T and carbon dioxide (CO2 during winemaking or bottling on the volatile profiles of white wines of Feteasca Regala. The study is based on the use of a flash gas chromatography electronic nose, which is able to discriminate various clusters of wine samples prepared with various combinations of antioxidants. The treatments that induce enough differences in the volatile profiles of the wine that the electronic nose is able to discriminate are likely to be discriminated also by the consumers. When the electronic nose does not discriminate the clusters of samples with certain treatments it is very likely that those treatments are not sufficient to induce a practically important difference in the aromatic profile of wines. The main detectable influences of the antioxidant treatments are presented and discussed. The treatment of musts with AA (50 mg/l clearly influences the volatile profile of the wines, reducing their aromatic complexity. The treatment during bottling with catechinic tannin (20 mg/l does not seem to have an important influence of the profile of the wines produced with the addition of AA and or GSH. The addition of carbon dioxide during bottling does not show much influence one year after bottling, but it shows that in the samples most prone to oxidation, a difference is present. The CO2 treated wines belonging to the cluster of wines treated with 40 mg/l GSH and 50 mg/l AA have distinct profiles, different from those not protected and closer to the clusters of the less oxidised wines. The treatment of musts with GSH shows clear influences at the dose of 40 mg/l, but for the lower dose of 20 mg/l GSH in Feteasca regala wines it is difficult to identify differences compared to the wines included in the cluster of samples not treated with GSH. This finding is particularly relevant as the
Flue gas treatment with membrane gas absorption
Klaassen, R.; Feron, P.H.M.; Jansen, A.E.
1998-01-01
Membrane gas absorption is a new, efficient and flexible way to carry out gas-liquid contacting operations with hollow fibre membranes. Advantages of gas absorption membranes over conventional G-L contactors are: -High specific surface area and rapid mass transfer resulting in very compact and low w
Energy Technology Data Exchange (ETDEWEB)
Syudzo, Y.; Nooya, Kh.
1984-05-28
A gas laser design that excludes direct contact between the gas medium and the atmosphere is proposed. The laser operates at a reduced gas pressure. After shutdown, a special system is used to increase the gas pressure inside the discharge chamber, which approaches atmospheric pressure. The laser employs an internal optical resonator. The electrical discharge which excites the gas medium originates from three electrodes located within the gas discharge tube.
Saadat, H
2015-01-01
In this paper, we study interacting extended Chaplygin gas as dark matter and quintessence scalar field as dark energy with an effective $\\Lambda$-term in Lyra manifold. As we know Chaplygin gas behaves as dark matter at the early universe while cosmological constant at the late time. Modified field equations are given and motivation of the phenomenological models discussed in details. Four different models based on the interaction term are investigated in this work. Then, we consider other models where Extended Chaplygin gas and quintessence field play role of dark matter and dark energy respectively with two different forms of interaction between the extended Chaplygin gas and quintessence scalar field for both constant and varying $\\Lambda$. Concerning to the mathematical hardness of the problems we discuss results numerically and graphically. Obtained results give us hope that proposed models can work as good models for the early universe with later stage of evolution containing accelerated expansion.
A Cosmological Model of the Early Universe Based on ECG with Variable Λ-Term in Lyra Geometry
Saadat, H.
2016-05-01
In this paper, we study interacting extended Chaplygin gas as dark matter and quintessence scalar field as dark energy with an effective Λ-term in Lyra manifold. As we know Chaplygin gas behaves as dark matter at the early universe while cosmological constant at the late time. Modified field equations are given and motivation of the phenomenological models discussed in details. Four different models based on the interaction term are investigated in this work. Then, we consider other models where Extended Chaplygin gas and quintessence field play role of dark matter and dark energy respectively with two different forms of interaction between the extended Chaplygin gas and quintessence scalar field for both constant and varying Λ. Concerning to the mathematical hardness of the problems we discuss results numerically and graphically. Obtained results give us hope that proposed models can work as good models for the early universe with later stage of evolution containing accelerated expansion.
46 CFR 197.340 - Breathing gas supply.
2010-10-01
... 46 Shipping 7 2010-10-01 2010-10-01 false Breathing gas supply. 197.340 Section 197.340 Shipping... GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.340 Breathing gas supply. (a) A primary breathing gas supply for surface-supplied diving must be sufficient to support the following for...
29 CFR 1910.426 - Mixed-gas diving.
2010-07-01
... 29 Labor 5 2010-07-01 2010-07-01 false Mixed-gas diving. 1910.426 Section 1910.426 Labor... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Commercial Diving Operations Specific Operations Procedures § 1910.426 Mixed-gas diving. (a) General. Employers engaged in mixed-gas diving shall comply with the...
46 CFR 118.410 - Fixed gas fire extinguishing systems.
2010-10-01
... 46 Shipping 4 2010-10-01 2010-10-01 false Fixed gas fire extinguishing systems. 118.410 Section... PROTECTION EQUIPMENT Fixed Fire Extinguishing and Detecting Systems § 118.410 Fixed gas fire extinguishing systems. (a) General. (1) A fixed gas fire extinguishing system aboard a vessel must be approved by...
2010-01-01
... CLIMATE CHANGE VOLUNTARY GREENHOUSE GAS REPORTING PROGRAM: GENERAL GUIDELINES § 300.1 General. (a) Purpose... protocols. Possible changes may include, but are not limited to: (1) The addition of greenhouse gases that... govern the Voluntary Reporting of Greenhouse Gases Program authorized by section 1605(b) of the...
Effects of gas types and models on optimized gas fuelling station reservoir's pressure
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...
Institute of Scientific and Technical Information of China (English)
冯静阁; 黄晓津
2015-01-01
This thesis analyzed digital procedures of the domestic and international nuclear power plant, combined with the own characteristics of the high temperature reactor demonstra-tion project (HTR-PM). The general design of digital procedure system (DPS) of the demonstra-tion project was studied by comprehensively utilizing the multi-disciplinary knowledge including the digital control system (DCS) technology, human factors engineering theory, and computer technology. It provides basis for further study of the system.%文章分析了国内外核电站数字化规程研究现状,结合高温气冷堆示范工程(H T R-P M)的自身特点,综合运用数字化仪控系统(D C S)技术、人因工程理论、计算机技术等多学科知识,对示范工程数字化规程系统的总体设计进行了研究,为该系统的进一步研发提供了基础.
Ho, Clifford K
2006-01-01
This book presents a compilation of state-of-the art studies on gas and vapor transport processes in porous and fractured media. A broad set of models and processes are presented, including advection/diffusion, the Dusty Gas Model, enhanced vapor diffusion, phase change, coupled processes, solid/vapor sorption, and vapor-pressure lowering. Numerous applications are also presented that illustrate these processes and models in current problems facing the scientific community. This book fills a gap in the general area of transport in porous and fractured media; an area that has historically been dominated by studies of liquid-phase flow and transport. This book identifies gas and vapor transport processes that may be important or dominant in various applications, and it exploits recent advances in computational modeling and experimental methods to present studies that distinguish the relative importance of various mechanisms of transport in complex media.
On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection
Nardon, E.; Fil, A.; Chauveau, P.; Tamain, P.; Guirlet, R.; Koslowski, H. R.; Lehnen, M.; Reux, C.; Saint-Laurent, F.; Contributors, JET
2017-01-01
A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013).
A Generalization of Generalized Fibonacci and Generalized Pell Numbers
Abd-Elhameed, W. M.; Zeyada, N. A.
2017-01-01
This paper is concerned with developing a new class of generalized numbers. The main advantage of this class is that it generalizes the two classes of generalized Fibonacci numbers and generalized Pell numbers. Some new identities involving these generalized numbers are obtained. In addition, the two well-known identities of Sury and Marques which…
Combustion heating value gas in a gas turbine
Energy Technology Data Exchange (ETDEWEB)
Kelsall, G. [CTDD, British Coal Corporation, Cheltenham (United Kingdom); Cannon, M. [European Gas Turbines Ltd., Lincoln (United Kingdom)
1996-12-31
Advanced coal and/or biomass based power generation systems offer the potential for high efficiency electricity generation with minimum environmental impact. An important component for many of these advanced power generation cycles is the gas turbine, for which development of a combustion system to burn low calorific value coal derived fuel gas, at turbine inlet temperatures of typically 1 100 - 1 260 deg C and with minimum pollutant emissions, is a key issue. A phased combustor development programme is under-way burning low calorific value fuel gas (3.6 - 4.1 MJ/m{sup 3}) with low emissions, particularly NO{sub x} derived from fuel-bound nitrogen. The first and second phases of the combustor development programme have been completed. The first phase used a generic tubo-annular, prototype combustor based on conventional design principles. Combustor performance for this first prototype combustor was encouraging. The second phase assessed five design variants of the prototype combustor, each variant achieving a progressive improvement in combustor performance. The operating conditions for this assessment were selected to represent a particular medium sized industrial gas turbine operating as part of an Air Blown Gasification Cycle (ABGC). The test conditions assessed therefore included the capability to operate the combustor using natural gas as a supplementary fuel, to suit one possible start-up procedure for the cycle. The paper presents a brief overview of the ABGC development initiative and discusses the general requirements for a gas turbine operating within such a cycle. In addition, it presents full combustor performance results for the second phase of turbine combustor development and discusses the rationale for the progressive design modifications made within that programme. The strategy for the further development of the combustor to burn low calorific value fuel gas with very low conversion of fuel-bound nitrogen to NO{sub x} is presented. (orig.) 6 refs.
Natural gas conversion process
Energy Technology Data Exchange (ETDEWEB)
1992-01-01
The experimental apparatus was dismantled and transferred to a laboratory space provided by Lawrence Berkeley Laboratory (LBL) which is already equipped with a high-ventilation fume hood. This will enable us to make tests at higher gas flow rates in a safe environment. Three papers presented at the ACS meeting in San Francisco (Symposium on Natural Gas Upgrading II) April 5--10, 1992 show that the goal of direct catalytic conversion of Methane into heavier Hydrocarbons in a reducing atmosphere is actively pursued in three other different laboratories. There are similarities in their general concept with our own approach, but the temperature range of the experiments reported in these recent papers is much lower and this leads to uneconomic conversion rates. This illustrates the advantages of Methane activation by a Hydrogen plasma to reach commercial conversion rates. A preliminary process flow diagram was established for the Integrated Process, which was outlined in the previous Quarterly Report. The flow diagram also includes all the required auxiliary facilities for product separation and recycle of the unconverted feed as well as for the preparation and compression of the Syngas by-product.
Hildebrand, Richard J.; Wozniak, John J.
2001-01-01
A compressed gas storage cell interconnecting manifold including a thermally activated pressure relief device, a manual safety shut-off valve, and a port for connecting the compressed gas storage cells to a motor vehicle power source and to a refueling adapter. The manifold is mechanically and pneumatically connected to a compressed gas storage cell by a bolt including a gas passage therein.
Energy Technology Data Exchange (ETDEWEB)
Jakob, K. [MOL Hungarian Oil and Gas Company, Budapest (Hungary)
1995-12-01
The goal of this presentation is to provide information on issues of crude oil and natural gas supply at a conference addressing the problems of energy in Eastern and Central Europe. Although this can inevitably be performed through the {open_quotes}binoculars{close_quotes} of the petroleum sector of my country, I will try to present the issues and challenges that are thought to be characteristic in general for the region.
Energy Technology Data Exchange (ETDEWEB)
Loehmannsroeben, H.G.; Schael, F.; Reich, O.
2000-12-01
The project covered the conception, development and characterisation for practical application in spectroscopy of a diode laser supported, fibre-optica measuring system for absorption and remission measurements in the spectral region of 660 - 1800 nm in in-situ investigations (diode laser in situ analsis, DISA). [German] Ziel des vorliegenden Projektes ist die Konzeption, der Aufbau und die Charakterisierung fuer den spaeteren spektroskopischen Einsatzes eines diodenlaser-gestuetzten, faseroptischen Messsystems fuer Absorptions- und Remissionsmessungen im Spektralbereich 660 bis 1800 nm bei in-situ Untersuchungen (Diodenlaser-In-Situ-Analysesystem, DISA). Hauptaufgaben des DISA ist die quantitative Bestimmung von Gasen und anderen wichtigen Inhaltsstoffen in heterogenen Systemen mit Gas-, Fluessig- und Festphasen. Dabei sind analytische und chemometrische Verfahren fuer absorptions- und remissionsspektroskopische Messungen in absorbierenden und stark streuenden Medien und Oberflaechen zu optimieren. Herausragende Anwendungen sind hier der direkte Nachweis von molekularem Sauerstoff, Glucose und aromatischen Molekuelen (BTXE) in Medien und unter Bedingungen, die eine Uebertragung der Ergebnisse fuer den Einsatz in poroesen Materialien, Geweben, Koerperfluessigkeiten und Umweltkompartimenten (Luft, Wasser, Boden) zulassen. Anwendungsbereiche des DISA ergeben sich u.a. in den Bereichen Medizintechnik, Umweltanalytik, Prozessmonitoring. (orig.)
Geological characteristics of large gas provinces and large gas fields in China
Institute of Scientific and Technical Information of China (English)
2008-01-01
Based on the examination of the global researches on oil and gas provinces and large gas fields and the analysis of the features,attributes and distribution of large gas provinces and gas fields,this paper puts forward three indicators of determining large oil and gas provinces:spatial indicator,reservoir-forming indicator and resource indicator.It classifies the gas accumulated areas and large gas provinces in China and analyzes the controlling factors on the distribution of large gas provinces and large gas fields:the lateral distribution is mainly controlled by high-energy sedimentary facies and constructive diagenetic facies,palaeo-highs and their periclinal zones,deep faults,etc,and the vertical distribution is mainly controlled by unconformities,series of evaporates and deep low-velocity highly-conductive beds,etc.It also reveals the main geological characteristics of large gas provinces and large gas fields in China.Large gas fields in four-type basins have their own characteristics and onland large gas fields are dominantly developed in foreland basins and craton basins;there are three types of gas sources,of which,coal is the main source with high gas generating intensity and varying origins;reservoir rocks of the large gas fields(provinces)are of various types and dominated generally by low-middle permeability and porosity pore-type reservoirs;structural traps and litho-stratigraphic traps coexist in Chinese large gas fields and form dense high abundance and large-area low and middle-abundance large gas fields;most of the large gas fields have late hydrocarbon-generation peaks and reservoir formation,and experienced the process of multiple-stage charging and late finalization; large gas provinces(fields)have good sealing and preservation conditions,and evaporates seals are largely developed in large and extra-large gas fields.This paper intends to shed light on the exploration and development of large gas fields(provinces)through analyzing their
Generalized periodic and generalized Boolean rings
Directory of Open Access Journals (Sweden)
Howard E. Bell
2001-01-01
Full Text Available We prove that a generalized periodic, as well as a generalized Boolean, ring is either commutative or periodic. We also prove that a generalized Boolean ring with central idempotents must be nil or commutative. We further consider conditions which imply the commutativity of a generalized periodic, or a generalized Boolean, ring.
Limit of Riemann Solutions to the Nonsymmetric System of Keyfitz-Kranzer Type
Directory of Open Access Journals (Sweden)
Lihui Guo
2014-01-01
Full Text Available The limit of Riemann solutions to the nonsymmetric system of Keyfitz-Kranzer type with a scaled pressure is considered for both polytropic gas and generalized Chaplygin gas. In the former case, the delta shock wave can be obtained as the limit of shock wave and contact discontinuity when u->u+ and the parameter ϵ tends to zero. The point is, the delta shock wave is not the one of transport equations, which is obviously different from cases of some other systems such as Euler equations or relativistic Euler equations. For the generalized Chaplygin gas, unlike the polytropic or isothermal gas, there exists a certain critical value ϵ2 depending only on the Riemann initial data, such that when ϵ drops to ϵ2, the delta shock wave appears as u->u+, which is actually a delta solution of the same system in one critical case. Then as ϵ becomes smaller and goes to zero at last, the delta shock wave solution is the exact one of transport equations. Furthermore, the vacuum states and contact discontinuities can be obtained as the limit of Riemann solutions when u-
General(es) remisión de V. escuelas general(es).
2011-01-01
[ES] Definición del término General(es) remisión de V. escuelas general(es). en el diccionario Dicter. [EN] Definition of the word General(es) remisión de V. escuelas general(es). in the dictionary Dicter.
Selective gas capture via kinetic trapping
Kundu, Joyjit; Prendergast, David; Whitelam, Stephen
2016-01-01
Conventional approaches to the capture of CO_2 by metal-organic frameworks focus on equilibrium conditions, and frameworks that contain little CO_2 in equilibrium are often rejected as carbon-capture materials. Here we use a statistical mechanical model, parameterized by quantum mechanical data, to suggest that metal-organic frameworks can be used to separate CO_2 from a typical flue gas mixture when used under {\\em nonequilibrium} conditions. The origin of this selectivity is an emergent gas-separation mechanism that results from the acquisition by different gas types of different mobilities within a crowded framework. The resulting distribution of gas types within the framework is in general spatially and dynamically heterogeneous. Our results suggest that relaxing the requirement of equilibrium can substantially increase the parameter space of conditions and materials for which selective gas capture can be effected.
A Survey on Gas Sensing Technology
Directory of Open Access Journals (Sweden)
Huansheng Ning
2012-07-01
Full Text Available Sensing technology has been widely investigated and utilized for gas detection. Due to the different applicability and inherent limitations of different gas sensing technologies, researchers have been working on different scenarios with enhanced gas sensor calibration. This paper reviews the descriptions, evaluation, comparison and recent developments in existing gas sensing technologies. A classification of sensing technologies is given, based on the variation of electrical and other properties. Detailed introduction to sensing methods based on electrical variation is discussed through further classification according to sensing materials, including metal oxide semiconductors, polymers, carbon nanotubes, and moisture absorbing materials. Methods based on other kinds of variations such as optical, calorimetric, acoustic and gas-chromatographic, are presented in a general way. Several suggestions related to future development are also discussed. Furthermore, this paper focuses on sensitivity and selectivity for performance indicators to compare different sensing technologies, analyzes the factors that influence these two indicators, and lists several corresponding improved approaches.
A Survey on Gas Sensing Technology
Liu, Xiao; Liu, Hong; Hu, Sha; Zhang, Daqiang; Ning, Huansheng
2013-01-01
Sensing technology has been widely investigated and utilized for gas detection. Due to the different applicability and inherent limitations of different gas sensing technologies, researchers have been working on different scenarios with enhanced gas sensor calibration. This paper reviews the descriptions, evaluation, comparison and recent developments in existing gas sensing technologies. A classification of sensing technologies is given, based on the variation of electrical and other properties. Detailed introduction to sensing methods based on electrical variation is discussed through further classification according to sensing materials, including metal oxide semiconductors, polymers, carbon nanotubes, and moisture absorbing materials. Methods based on other kinds of variations such as optical, calorimetric, acoustic and gas-chromatographic, are presented in a general way. Several suggestions related to future development are also discussed. Furthermore, this paper focuses on sensitivity and selectivity fo...
Henderson, Timothy M.; Wuttke, Gilbert H.
1977-01-01
A variable leak gas source and a method for obtaining the same which includes filling a quantity of hollow glass micro-spheres with a gas, storing said quantity in a confined chamber having a controllable outlet, heating said chamber above room temperature, and controlling the temperature of said chamber to control the quantity of gas passing out of said controllable outlet. Individual gas filled spheres may be utilized for calibration purposes by breaking a sphere having a known quantity of a known gas to calibrate a gas detection apparatus.
Flue gas treatment with membrane gas absorption
Klaassen, R.; Feron, P.H.M.; Jansen, A.E.
1998-01-01
Dutch researchers from the TN0 Institute have developed a technique to carry out gas-liquid contacting operations using hollow fibre membranes in combination with an absorption liquid. The method known as membrane gas absorption, aims to combine the advantages of membrane technology (compactness, fl
Gas purification using membrane gas absorption processes
Dindore, V.Y.
2003-01-01
Owing to the increasing energy demand and the abundance of low quality natural gas reservoirs containing high percentages of CO2, considerable attention is given to the bulk removal of CO2 and upgrading of low quality natural gas. The main goal in doing so is to increase the heating value of natural
HD 95881: A gas rich to gas poor transition disk?
Verhoeff, A P; Acke, B; van Boekel, R; Pantin, E; Waters, L B F M; Tielens, A G G M; Ancker, M E van den; Mulders, G D; de Koter, A; Bouwman, J
2010-01-01
Context. Based on the far infrared excess the Herbig class of stars is divided into a group with flaring circumstellar disks (group I) and a group with flat circumstellar disks (group II). Dust sedimentation is generally proposed as an evolution mechanism to transform flaring disks into flat disks. Theory predicts that during this process the disks preserve their gas content, however observations of group II Herbig Ae stars demonstrate a lack of gas. Aims. We map the spatial distribution of the gas and dust around the group II Herbig Ae star HD 95881. Methods. We analyze optical photometry, Q-band imaging, infrared spectroscopy, and K and N-band interferometric spectroscopy. We use a Monte Carlo radiative transfer code to create a model for the density and temperature structure which quite accurately reproduces all the observables. Results. We derive a consistent picture in which the disk consists of a thick puffed up inner rim and an outer region which has a flaring gas surface and is relatively void of 'vis...
A general approach to bosonization
Indian Academy of Sciences (India)
Girish S Setulur; V Meera
2007-10-01
We summarize recent developments in the ﬁeld of higher dimensional bosonization made by Setlur and collaborators and propose a general formula for the ﬁeld operator in terms of currents and densities in one dimension using a new ingredient known as a `singular complex number'. Using this formalism, we compute the Green function of the homogeneous electron gas in one spatial dimension with short-range interaction leading to the Luttinger liquid and also with long-range interactions that lead to a Wigner crystal whose momentum distribution computed recently exhibits essential singularities. We generalize the formalism to ﬁnite temperature by combining with the author's hydrodynamic approach. The one-particle Green function of this system with essential singularities cannot be easily computed using the traditional approach to bosonization which involves the introduction of momentum cutoffs, hence the more general approach of the present formalism is proposed as a suitable alternative.
Energy Technology Data Exchange (ETDEWEB)
Cho, Yong Sung [Korea Energy Economics Institute, Euiwang (Korea)
1999-04-01
With the increase of convenient and clean gas fuel consumption, the danger of gas safety accident is also increasing. Therefore, now is the time for requiring many thoughtful concerns and cares for the prevention of gas accident. In this study, the perception of city gas end users on use of city gas was studied and the economic value of improving gas safety was estimated by examining the intended amount paid for improving safety of city gas use. Although most of city gas end-users perceive that gas use is generally safe, they are concerned about a possibility of dander of accidents happened without any notice. On the other hand, about 97% of households using city gas know checking gas safety at a minimum, but only 60% among them are implementing self-checkup. The economic benefit of improving gas safety of city gas end-users in Korea is estimated from the lowest of 121.47 billion to the highest of 317.97 billion annually. (author). 38 refs., 5 figs., 45 tabs.
Compressed Gas Safety for Experimental Fusion Facilities
Energy Technology Data Exchange (ETDEWEB)
Lee C. Cadwallader
2004-09-01
Experimental fusion facilities present a variety of hazards to the operators and staff. There are unique or specialized hazards, including magnetic fields, cryogens, radio frequency emissions, and vacuum reservoirs. There are also more general industrial hazards, such as a wide variety of electrical power, pressurized air, and cooling water systems in use, there are crane and hoist loads, working at height, and handling compressed gas cylinders. This paper outlines the projectile hazard assoicated with compressed gas cylinders and mthods of treatment to provide for compressed gas safety. This information should be of interest to personnel at both magnetic and inertial fusion experiments.
Compressed Gas Safety for Experimental Fusion Facilities
Energy Technology Data Exchange (ETDEWEB)
Lee C. Cadwallader
2004-09-01
Experimental fusion facilities present a variety of hazards to the operators and staff. There are unique or specialized hazards, including magnetic fields, cryogens, radio frequency emissions, and vacuum reservoirs. There are also more general industrial hazards, such as a wide variety of electrical power, pressurized air, and cooling water systems in use, there are crane and hoist loads, working at height, and handling compressed gas cylinders. This paper outlines the projectile hazard assoicated with compressed gas cylinders and mthods of treatment to provide for compressed gas safety. This information should be of interest to personnel at both magnetic and inertial fusion experiments.
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.
Institute of Scientific and Technical Information of China (English)
李晓征; 李界平; 王强; 于海芳; 张芸
2012-01-01
目的:探讨参附注射液对全麻复合胸段硬膜外阻滞下行肺叶切除术患者血流动力学及血气分析指标的影响.方法:将60例拟在胸段硬膜外阻滞复合全麻下肺叶切除术病人,随机双盲法分为参附组(n=30)及对照组(n=30),参附组在麻醉诱导前静脉输注参附注射液1.5 mL/kg;对照组以同样速度输注等量的生理盐水.结果:与对照组相比,参附组的MAP、HR在诱导后5 min(T1)、手术探查时(T2)、单肺通气30 min(T3)、单肺通气60 min(T4)及关胸前冲洗胸腔时(T5)升高(P＜ 0.05),术中麻黄碱、阿托品的使用量及输液总量减少(P＜ 0.05),PaO2在T3、T4 时较对照组升高(P＜ 0.05),麻醉药物用量等两组比较无差异(P＞ 0.05).结论:参附注射液对胸段硬膜外阻滞复合全麻下肺叶切除术患者血流动力学变化具有稳定作用,可改善单肺通气期间血气分析指标.%Objective To investigate the effect of Shenfu Injection on hemodynamics and blood gas analysis in patients undergoing lobectoiny oi lung combined thoracic epidural block and general anesthesia.Methods A double blind trail was conducted on 60 patients undergoing lobectomy of lung combined thoracic epidural block and general anesthesia.The patients were randomly divided into Shenfu Injection group (n=30) and control group (n=30). In the Shenfu Injection group, 1.5 mL/kg Shenfu Injection diluted with 250 mL saline were given before anesthesia introduction. In the control group, equal saline were given at the same time. The following indexes were observed: (1) MAP,HR and CVP at the time before anesthesia introduction (TO), after anesthesia introduction for 5 minutes(T1), surgical exploration(T2),after one-lung ventilation for 30 minutes(T3), after one-lung ventilation for 60 minutes(T4), rinse chest(T5) and the end of operation(T6).(2)the dose of atropine and ephedrine, the amount of intraoperative transfusion,blood loss, urine volume and duration of surgery.(3) the
NATURAL GAS RESOURCES IN DEEP SEDIMENTARY BASINS
Energy Technology Data Exchange (ETDEWEB)
Thaddeus S. Dyman; Troy Cook; Robert A. Crovelli; Allison A. Henry; Timothy C. Hester; Ronald C. Johnson; Michael D. Lewan; Vito F. Nuccio; James W. Schmoker; Dennis B. Riggin; Christopher J. Schenk
2002-02-05
From a geological perspective, deep natural gas resources are generally defined as resources occurring in reservoirs at or below 15,000 feet, whereas ultra-deep gas occurs below 25,000 feet. From an operational point of view, ''deep'' is often thought of in a relative sense based on the geologic and engineering knowledge of gas (and oil) resources in a particular area. Deep gas can be found in either conventionally-trapped or unconventional basin-center accumulations that are essentially large single fields having spatial dimensions often exceeding those of conventional fields. Exploration for deep conventional and unconventional basin-center natural gas resources deserves special attention because these resources are widespread and occur in diverse geologic environments. In 1995, the U.S. Geological Survey estimated that 939 TCF of technically recoverable natural gas remained to be discovered or was part of reserve appreciation from known fields in the onshore areas and State waters of the United. Of this USGS resource, nearly 114 trillion cubic feet (Tcf) of technically-recoverable gas remains to be discovered from deep sedimentary basins. Worldwide estimates of deep gas are also high. The U.S. Geological Survey World Petroleum Assessment 2000 Project recently estimated a world mean undiscovered conventional gas resource outside the U.S. of 844 Tcf below 4.5 km (about 15,000 feet). Less is known about the origins of deep gas than about the origins of gas at shallower depths because fewer wells have been drilled into the deeper portions of many basins. Some of the many factors contributing to the origin of deep gas include the thermal stability of methane, the role of water and non-hydrocarbon gases in natural gas generation, porosity loss with increasing thermal maturity, the kinetics of deep gas generation, thermal cracking of oil to gas, and source rock potential based on thermal maturity and kerogen type. Recent experimental simulations
Cylindrical wormholes with positive cosmological constant
Richarte, Mart'\\in G
2013-01-01
We construct cylindrical, traversable wormholes with finite radii by taking into account the cut-and-paste procedure for the case of cosmic string manifolds with a positive cosmological constant. Under reasonable assumptions about the equation of state of the matter located at the shell, we find that the wormhole throat undergoes a monotonous evolution provided it moves at a constant velocity. In order to explore the dynamical nonlinear behaviour of the wormhole throat, we consider that the matter at the shell is supported by anisotropic Chaplygin gas, anti-Chaplygin gas, or a mixed of Chaplygin and anti-Chaplygin gases implying that wormholes could suffer an accelerated expansion or contraction but the oscillatory behavior seems to be forbidden.
Cylindrical wormholes with positive cosmological constant
Richarte, Martín G.
2013-07-01
We construct cylindrical, traversable wormholes with finite radii by taking into account the cut-and-paste procedure for the case of cosmic string manifolds with a positive cosmological constant. Under reasonable assumptions about the equation of state of the matter located at the shell, we find that the wormhole throat undergoes a monotonous evolution provided it moves at a constant velocity. In order to explore the dynamical nonlinear behavior of the wormhole throat, we consider that the matter of the shell is supported by anisotropic Chaplygin gas, anti-Chaplygin gas, or a mixture of Chaplygin and anti-Chaplygin gases, implying that wormholes could suffer an accelerated expansion or contraction, but that oscillatory behavior seems to be forbidden.
Energy Technology Data Exchange (ETDEWEB)
NONE
1997-09-01
This document provides information on the supply and disposition of natural gas to a wide audience. The 1996 data are presented in a sequence that follows natural gas from it`s production to it`s end use.
Sulphur hexafluoride gas detection
CSIR Research Space (South Africa)
Stolper, R
2006-02-01
Full Text Available This poster describes the development process of an electro-optical based solution for detecting and locating SF6 gas leaks at gas insulated switch gear. The principal technologies that were researched are explained with their advantages...
Energy Technology Data Exchange (ETDEWEB)
None
2016-06-08
Natural gas powers about 150,000 vehicles in the United States and roughly 22 million vehicles worldwide. Natural gas vehicles (NGVs) are a good choice for high-mileage fleets -- such as buses, taxis, and refuse vehicles -- that are centrally fueled or operate within a limited area or along a route with natural gas fueling stations. This brochure highlights the advantages of natural gas as an alternative fuel, including its domestic availability, established distribution network, relatively low cost, and emissions benefits.
Energy Technology Data Exchange (ETDEWEB)
2016-06-01
Natural gas powers about 150,000 vehicles in the United States and roughly 22 million vehicles worldwide. Natural gas vehicles (NGVs) are a good choice for high-mileage fleets -- such as buses, taxis, and refuse vehicles -- that are centrally fueled or operate within a limited area or along a route with natural gas fueling stations. This brochure highlights the advantages of natural gas as an alternative fuel, including its domestic availability, established distribution network, relatively low cost, and emissions benefits.
Institute of Scientific and Technical Information of China (English)
Chu Haihong
2005-01-01
@@ According to JPMorgan's review 2003 of China's gas market,China's household gas price was one of the lowest in the world, 20% below the global average. Despite the increase in recent years, China's domestic gas price is still relatively low in the global context. It is safe to say that the low gas price is one of the keys attracting keen investments currently from overseas and domestic private capitals.
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-11-17
The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. The 1994 data are presented in a sequence that follows natural gas (including supplemental supplies) from its production to its end use. This is followed by tables summarizing natural gas supply and disposition from 1990 to 1994 for each Census Division and each State. Annual historical data are shown at the national level.
Bowers, Michael T
1979-01-01
Gas Phase Ion Chemistry, Volume 2 covers the advances in gas phase ion chemistry. The book discusses the stabilities of positive ions from equilibrium gas-phase basicity measurements; the experimental methods used to determine molecular electron affinities, specifically photoelectron spectroscopy, photodetachment spectroscopy, charge transfer, and collisional ionization; and the gas-phase acidity scale. The text also describes the basis of the technique of chemical ionization mass spectrometry; the energetics and mechanisms of unimolecular reactions of positive ions; and the photodissociation
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-11-01
The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. The 1995 data are presented in a sequence that follows natural gas (including supplemental supplies) from its production to its end use. This is followed by tables summarizing natural gas supply and disposition from 1991 to 1995 for each Census Division and each State. Annual historical data are shown at the national level.
Liquid propellant gas generators
1972-01-01
The design of gas generators intended to provide hot gases for turbine drive is discussed. Emphasis is placed on the design and operation of bipropellant gas generators because of their wider use. Problems and limitations involved in turbine operation due to temperature effects are analyzed. Methods of temperature control of gas turbines and combustion products are examined. Drawings of critical sections of gas turbines to show their operation and areas of stress are included.
Natural gas as public service; Gas natural como servico publico
Energy Technology Data Exchange (ETDEWEB)
Gois, Breno Vincius de; Franca, Vladimir da Rocha [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)
2008-07-01
The Natural Gas passes through an outbreak of enormous growth in Brazil. Important in several economies in the world and is one of the main components of the energy matrix of various countries, including neighbouring Southern Cone, such as Argentina and Bolivia, he begins to own as a major viable alternatives to replace oil, along with alcohol and biodiesel. When the distribution of the gas flowing, this should be governed by a system of public law, according to the principles governing the administration, is emphasizing the principle of continuity, efficiency, and generally modest, because this is public service, and how to see this be seen on a strong regulation of the Member States of the Federation, which has the power to provide them directly or by concession. (author)
Mattson, Bruce; Anderson, Michael P.
2011-01-01
The development of syringes having free movement while remaining gas-tight enabled methods in chemistry to be changed. Successfully containing and measuring volumes of gas without the need to trap them using liquids made it possible to work with smaller quantities. The invention of the LuerLok syringe cap also allowed the gas to be stored for a…
Holko, David A.
1982-01-01
Presents a complete computer program demonstrating the relationship between volume/pressure for Boyle's Law, volume/temperature for Charles' Law, and volume/moles of gas for Avagadro's Law. The programing reinforces students' application of gas laws and equates a simulated moving piston to theoretical values derived using the ideal gas law.…
Prospecting for marine gas hydrate resources
Boswell, Ray; Shipp, Craig; Reichel, Thomas; Shelander, Dianna; Saeki, Tetsuo; Frye, Matthew; Shedd, William; Collett, Timothy S.; McConnell, Daniel R.
2016-01-01
As gas hydrate energy assessment matures worldwide, emphasis has evolved away from confirmation of the mere presence of gas hydrate to the more complex issue of prospecting for those specific accumulations that are viable resource targets. Gas hydrate exploration now integrates the unique pressure and temperature preconditions for gas hydrate occurrence with those concepts and practices that are the basis for conventional oil and gas exploration. We have aimed to assimilate the lessons learned to date in global gas hydrate exploration to outline a generalized prospecting approach as follows: (1) use existing well and geophysical data to delineate the gas hydrate stability zone (GHSZ), (2) identify and evaluate potential direct indications of hydrate occurrence through evaluation of interval of elevated acoustic velocity and/or seismic events of prospective amplitude and polarity, (3) mitigate geologic risk via regional seismic and stratigraphic facies analysis as well as seismic mapping of amplitude distribution along prospective horizons, and (4) mitigate further prospect risk through assessment of the evidence of gas presence and migration into the GHSZ. Although a wide range of occurrence types might ultimately become viable energy supply options, this approach, which has been tested in only a small number of locations worldwide, has directed prospect evaluation toward those sand-hosted, high-saturation occurrences that were presently considered to have the greatest future commercial potential.
Gas-influx detection with MWD technology
Energy Technology Data Exchange (ETDEWEB)
Bryant, T.M.; Grosso, D.S.; Wallace, S.N. (Teleco Oilfield Services (US))
1991-12-01
This paper describes a new gas-influx detection technique that monitors the acoustic responses of annular measurement-while-drilling (MWD) pulses to provide a rapid, early warning of the development of potential gas-kick situations. The technique has been evaluated in both water- and oil-based muds during about 40 gas-kick simulations at two full-scale testing facilities. Free gas is identified by amplitude attenuation and phase delay of MWD fundamentals and their harmonic frequencies. Detection is independent of influx location because the entire length of the annulus between the bit nozzles and a surface-pressure transducer is sampled. Detection of potential gas-kick situations generally occurred within minutes of influx initiation, before any significant gas expansion. Some tests also evaluated a downhole MWD mud-resistivity sensor. Results indicated that both these techniques, and particularly the pulse acoustics, can provide unequivocal confirmation of gas and an earlier warning of gas-kick situations than conventional kick- detection techniques.
Challenges and Opportunities of China Oil & Gas Industry
Institute of Scientific and Technical Information of China (English)
Qian Xingkun
2015-01-01
Chinese economy has turned from rapid development into new normal. With economic transition, demand for oil and gas decreases as well. Consumed diesel-gasoline ratio keeps declining, and diesel export increases considerably. Gas demand grows at medium speed, and supply meets demand in general. Alternative energy dominated by gas and electricity will develop faster. As crude oil import right is gradually liberalized, domestic oil market structure will be changed. Oil price drop brings the best opportunity for oil and gas market reform, and environmental protection becomes main force boosting natural gas development.
Natural Gas Gathering and Purification in Sichuan Gas Fields
Institute of Scientific and Technical Information of China (English)
Zhang Zhilin
1996-01-01
@@ Natural Gas Gathering and Transmission Technology The construction of gas gathering & transmission lines and stations is an important part of the surface construction of gas fields, whose investment accounts for about half of the total in gas field's development.
Energy Technology Data Exchange (ETDEWEB)
NONE
1997-06-01
The Albany Interim Landfill Gas Extraction and Mobile Power System project served three research objectives: (1) determination of the general efficiency and radius of influence of horizontally placed landfill gas extraction conduits; (2) determination of cost and effectiveness of a hydrogen sulfide gas scrubber utilizing Enviro-Scrub{trademark} liquid reagent; and (3) construction and evaluation of a dual-fuel (landfill gas/diesel) 100 kW mobile power station. The horizontal gas extraction system was very successful; overall, gas recovery was high and the practical radius of influence of individual extractors was about 50 feet. The hydrogen sulfide scrubber was effective and its use appears feasible at typical hydrogen sulfide concentrations and gas flows. The dual-fuel mobile power station performed dependably and was able to deliver smooth power output under varying load and landfill gas fuel conditions.
Directory of Open Access Journals (Sweden)
Pietraru V.
2006-11-01
reservoirs [1]. This article gives a generalized description of this method for confined reservoirs. The case corresponding to a horizontal top is considered (bottom water drive and gas-cap drive. The generalization proposed is based on the solving of differential equations for diffusivity, while taking gravity drainage effects and boundary conditions into consideration for a confined reservoir. The method can be applied to isotropic or anisotropic reservoirs. The principal contributions of this article are :- Introduction of the concept of coning radius, differing from the well radius. The coning height and critical flow rate depend on the coning radius, whereas they are independent of the well radius. - A new correlation for calculating the critical flow rate in an adimensional from as a function of three parameters :. time,. length of the horizontal drain hole (zero for a vertical well, . and drainage radius. - Correlations for calculating the gas/oil ratios (GOR or the water fraction (fw during critical and postcritical periods, which take capillary pressure and relative permeabilities into consideration. - Correlations for calculating the gas/oil and water/oil ratios during the pre, post and supercritical periods of dual coning. - Criteria for calculating the breakthrough time at the well for simple gas or water coning, or for dual gas or water coning. The critical flow rate varies with time. It depends on the geometric and physical parameters of the reservoir, such as the thickness of the layer or the drainage area of the well, and on an important parameter, the coning radius, which will be defined hereunder. On the contrary, the critical flow rate does not depend on the parameters characterizing the well or the near-well vicinity, i. e. the radius and damage (skin.N.B. No confusion must be made between the critical flow rate due to coning and other flow rates associated with the way the well operates, such as the potential flow rate of the well defined by the
A Generalized Fluid Formulation for Turbomachinery Computations
Merkle, Charles L.; Sankaran, Venkateswaran; Dorney, Daniel J.; Sondak, Douglas L.
2003-01-01
A generalized formulation of the equations of motion of an arbitrary fluid are developed for the purpose of defining a common iterative algorithm for computational procedures. The method makes use of the equations of motion in conservation form with separate pseudo-time derivatives used for defining the numerical flux for a Riemann solver and the convergence algorithm. The partial differential equations are complemented by an thermodynamic and caloric equations of state of a complexity necessary for describing the fluid. Representative solutions with a new code based on this general equation formulation are provided for three turbomachinery problems. The first uses air as a working fluid while the second uses gaseous oxygen in a regime in which real gas effects are of little importance. These nearly perfect gas computations provide a basis for comparing with existing perfect gas code computations. The third case is for the flow of liquid oxygen through a turbine where real gas effects are significant. Vortex shedding predictions with the LOX formulations reduce the discrepancy between perfect gas computations and experiment by approximately an order of magnitude, thereby verifying the real gas formulation as well as providing an effective case where its capabilities are necessary.
Marketing mix - commercial gas
Energy Technology Data Exchange (ETDEWEB)
Ford, M.F.
1975-07-01
British Gas Corp. points out that a substantial increase in the use of gas in Great Britain's commercial energy market has occurred in the past 6 yr. Some of the newest applications of gas are in the areas of the cook/freeze system of preparing frozen foods in commercial catering, commissariats preparing in-flight food, and heating/cooling systems of large buildings. The variety of buildings and institutions using gas-fired systems indicates that, with the sensible pricing policies and the security of an indigenous fuel, the commercial market for gas will continue to develop for several years in Britain.
Gas Hydrate Storage of Natural Gas
Energy Technology Data Exchange (ETDEWEB)
Rudy Rogers; John Etheridge
2006-03-31
Environmental and economic benefits could accrue from a safe, above-ground, natural-gas storage process allowing electric power plants to utilize natural gas for peak load demands; numerous other applications of a gas storage process exist. A laboratory study conducted in 1999 to determine the feasibility of a gas-hydrates storage process looked promising. The subsequent scale-up of the process was designed to preserve important features of the laboratory apparatus: (1) symmetry of hydrate accumulation, (2) favorable surface area to volume ratio, (3) heat exchanger surfaces serving as hydrate adsorption surfaces, (4) refrigeration system to remove heat liberated from bulk hydrate formation, (5) rapid hydrate formation in a non-stirred system, (6) hydrate self-packing, and (7) heat-exchanger/adsorption plates serving dual purposes to add or extract energy for hydrate formation or decomposition. The hydrate formation/storage/decomposition Proof-of-Concept (POC) pressure vessel and supporting equipment were designed, constructed, and tested. This final report details the design of the scaled POC gas-hydrate storage process, some comments on its fabrication and installation, checkout of the equipment, procedures for conducting the experimental tests, and the test results. The design, construction, and installation of the equipment were on budget target, as was the tests that were subsequently conducted. The budget proposed was met. The primary goal of storing 5000-scf of natural gas in the gas hydrates was exceeded in the final test, as 5289-scf of gas storage was achieved in 54.33 hours. After this 54.33-hour period, as pressure in the formation vessel declined, additional gas went into the hydrates until equilibrium pressure/temperature was reached, so that ultimately more than the 5289-scf storage was achieved. The time required to store the 5000-scf (48.1 hours of operating time) was longer than designed. The lower gas hydrate formation rate is attributed to a
Buffer Gas Acquisition and Storage
Parrish, Clyde F.; Lueck, Dale E.; Jennings, Paul A.; Callahan, Richard A.; Delgado, H. (Technical Monitor)
2001-01-01
The acquisition and storage of buffer gases (primarily argon and nitrogen) from the Mars atmosphere provides a valuable resource for blanketing and pressurizing fuel tanks and as a buffer gas for breathing air for manned missions. During the acquisition of carbon dioxide (CO2), whether by sorption bed or cryo-freezer, the accompanying buffer gases build up in the carbon dioxide acquisition system, reduce the flow of CO2 to the bed, and lower system efficiency. It is this build up of buffer gases that provide a convenient source, which must be removed, for efficient capture Of CO2 Removal of this buffer gas barrier greatly improves the charging rate of the CO2 acquisition bed and, thereby, maintains the fuel production rates required for a successful mission. Consequently, the acquisition, purification, and storage of these buffer gases are important goals of ISRU plans. Purity of the buffer gases is a concern e.g., if the CO, freezer operates at 140 K, the composition of the inert gas would be approximately 21 percent CO2, 50 percent nitrogen, and 29 percent argon. Although there are several approaches that could be used, this effort focused on a hollow-fiber membrane (HFM) separation method. This study measured the permeation rates of CO2, nitrogen (ND, and argon (Ar) through a multiple-membrane system and the individual membranes from room temperature to 193K and 10 kpa to 300 kPa. Concentrations were measured with a gas chromatograph that used a thermoconductivity (TCD) detector with helium (He) as the carrier gas. The general trend as the temperature was lowered was for the membranes to become more selective, In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar.
TIS General Safety Group Annual Report 2000
Weingarten, W
2001-01-01
This report summarises the main activities of the General Safety (GS) Group of the Technical Inspection and Safety Division (TIS) during the year 2000, and the results obtained. The different topics in which the Group is active are covered: general safety inspections and ergonomy, electrical, chemistry and gas safety, chemical pollution containment and control, industrial hygiene, the safety of civil engineering works and outside contractors, fire prevention and the safety aspects of the LHC experiments.
Energy Technology Data Exchange (ETDEWEB)
Kelsall, G.J.; Fantom, I.R.; Laughlin, K.M.; King, R.J.; Watkins, C.J.; Williams, J.D.H.; Blenkin, P. [British Coal Corporation (United Kingdom). Coal Technology Development Division
1995-08-01
Advanced coal based power generation systems such as the Air Blown Gasification Cycle (ABGC), formerly known as the CTDD Topping Cycle, offer the potential for high efficiency electricity generation with low environmental impact. An important component of the ABGC development programme has been the determination of alkali metal compounds, dust and other trace contaminant species concentrations that would be contained in the combusted fuel gas presented to the gas turbine. These species are an important factor in the prediction of gas turbine component lifetimes when firing coal derived fuel gas. A project supported under the UK Department of Trade and Industry`s Coal Research and Development programme and the European Communities Commission THERMIE programme, was therefore devised to measure these contaminant species in a purpose built gas cleaning and combustion facility (Gas Utilisation Facility). This facility contained gas cleaning and combustion sytems representative of those that would be used in an ABGC utility application. The objective of this project was therefore to provide data on the level of certain contaminants present in the turbine expansion gas after passing through a low calorific value fuel gas, gas turbine combustor. This fuel gas was produced by the CTDD spouted fluidised bed gasifier and cleaned by filtration at up to 600{degree}C in the purpose built Gas Utilisation Facility. The data has been related to an existing materials test programme associated with the Grimethorpe Topping Cycle Project, which had the objective of predicting gas turbine component lifetimes in utility gas turbine machines. 22 refs., 12 figs., 8 tabs.
Gas hydrate, fluid flow and free gas: Formation of the bottom-simulating reflector
Haacke, R. Ross; Westbrook, Graham K.; Hyndman, Roy D.
2007-09-01
to resolve a number of problems. These include why sub-BSR free-gas zones are generally thin in convergent margins and thick in passive margins, and why areas such as the Gulf of Mexico and Mackenzie Delta do not have regional BSRs. Finally, we use our understanding of how BSRs are formed to show that regional gas hydrate is unlikely to exist in substantial quantities in passive continental margins outside areas with an observable BSR.
Emergency gas pipeline transportation with computer documentation
Energy Technology Data Exchange (ETDEWEB)
None
1978-08-01
Methods developed by the staff of the Federal Energy Regulatory Commission in cooperation with the natural gas industry to expedite the emergency transfer of natural gas are described. The majority of the United States' natural gas fields are concentrated in the south central region, comprised of Louisiana, Oklahoma, and Texas together with adjacent areas offshore in the Gulf of Mexico. This is the major source area for gas consumed in the northern, northeastern, southeastern, and far western population/industrial centers. The geographic pattern of gas flow through interstate pipelines emanates in gas producing areas and terminates in gas consuming areas. There are many other areas in the United States which produce gas but the amounts are comparatively small compared with Texas, Louisiana, and offshore Louisiana production. The various interconnections associated with a given pipeline for both receipts and deliveries are defined. The maximum volume capability in MMCFD and the volume being delivered in MMCFD are to be considered as estimated volumes. These volumes do not represent absolute volumes that are available but rather volumes for general planning purposes to define the magnitude of each interconnection. If an actual transportation route is desired, a routing may be derived from this report which then must be checked for actual volumes at a particular point in time. It is always possible that at the time of interest, there is no available capacity or deliveries.The data and information are arranged by pipeline company name followed by which companies supply gas to the named pipeline and to which companies the named pipeline delivers gas. Each receipt or delivery location is defined by the county and state.
Inventory non-conventional gas
Energy Technology Data Exchange (ETDEWEB)
Muntendam-Bos, A.G.; Wassing, B.B.T.; Ter Heege, J.H.; Van Bergen, F.; Schavemaker, Y.A.; Van Gessel, S.F.; De Jong, M.L.; Nelskamp, S.; Van Thienen-Visser, K.; Guasti, E.; Van den Belt; Marges, V.C. [TNO Built Environment and Geosciences, Utrecht (Netherlands)
2009-10-15
This report describes the results of the inventory for each non-conventional gas resource expected to be present in the Netherlands, which are: Tight Gas, Shallow gas, Coal bed Methane (CBM), Shale gas, Basin Centered Gas, Aquifer Gas and Stratigraphic traps.
Energy Technology Data Exchange (ETDEWEB)
Wajnberg, Sergio [Mat-Incendio S.A., Cajamar, SP (Brazil)
1999-07-01
This work generally describes important aspects related to the quality of Seamless Steel Cylinders used with Compressed Natural Gas in vehicles which are converted in Brazil to use this kind of fuel. In addition to the manufacturing process, the necessity of a correct usage, maintenance and control of these cylinders are emphasized. (author)
Institute of Scientific and Technical Information of China (English)
王泽璞; 刘石; 陈江涛; 周磊
2013-01-01
Through monitoring the flow speed and rate of a gas-solid two phase flow, the flow characteristics of the fluid transmitted was clarified and the pneumatic transmission process was successfully performed. The capacitance topography technology is regarded as one of technologies for detecting a gas-solid two phase flow and the key lies in its image rebuilding link. Through choosing a proper image rebuilding algorithm, one can reversely deduct the distribution characteristics of the fluid transmitted in a section. To improve the rebuilding image quality of the ECT system and enhance the accuracy of the detection technology, presented was a generalized dynamic image rebuilding algorithm integrating the space restriction, time restriction and reverse deduction information of the fluid flow. By analyzing and comparing the numerical test and the conventional image rebuilding algorithm, the authors believe that the image structure rebuilt by using the algorithm in question should be clearest. The test showed the pulverized coal and ash pneumatic transmission process as reversely deducted by using the algorithm in question. Both coal and ash obviously embodied the advantage of the dynamic rebuilding algorithm.%通过监测气固两相流的流速和流量值,明晰输送流体的流动特性,确保气力输送过程顺利进行.电容层析成像技术作为气固多相流的检测技术之一,关键是图像重建环节.通过选取恰当的图像重建算法,反演被输送流体的截面分布特性.为了改善ECT系统的重建图像质量,提高检测技术的精确性,提出一种集合被测流体的空间约束、时间约束和流体的流动反演信息的广义动态图像重建算法.将数值试验与常规的图像重建算法分析比较发现,该算法的重建图像结构最清晰.实验呈现用该算法反演的气力输送粉煤灰过程.两者明显体现了该动态重建算法的优势.
Introduction to Reactive Gas Dynamics
Brun, Raymond
2009-01-01
In high energy gas flows, at high velocities and high temperatures, physical and chemical processes such as molecular vibrational excitation, dissociation, ionisation or various reactions take place and deeply influence the structure of the flows. The characteristic times of these processes have the same order of magnitude as aerodynamic characteristic times, so that these reactive media are generally in thermodynamic and chemical non-equilibrium. This book presents a generalintroductory study of these media. In the first part their fundamental statistical aspects are described, starting from
Elementary processes in gas discharges
Bronold, Franz X
2008-01-01
This chapter presents, from a quantum-mechanical point of view, a tutorial discussion of elementary collision processes in the bulk of a gas discharge. Instead of merely listing kitchen-made cross section formulae and unrelated cross section data, emphasis has been given on an unified description of elementary processes based on general principles of quantum-mechanical multi-channel scattering theory. By necessity, the presentation is rather dense. Technical details left out, as well as cross section data, can be found, respectively, in the quoted original papers and the review articles, monographs, and web-sites mentioned in the introductory remarks to this chapter.
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.
Thermodynamic behavior and stability of Polytropic gas
Moradpour, H; Ebadi, H
2016-01-01
We focus on the thermodynamic behavior of Polytropic gas as a candidate for dark energy. We use the general arguments of thermodynamics to investigate its properties and behavior. We find that a Polytropic gas may exhibit the dark energy like behavior in the large volume and low temperature limits. It also may be used to simulate a fluid with zero pressure at the small volume and high temperature limits. Briefly, our study shows that this gas may be used to describe the universe expansion history from the matter dominated era to the current accelerating era. By applying some initial condition to the system, we can establish a relation between the Polytropic gas parameters and initial conditions. Relationships with related works has also been addressed.
40 CFR 600.201-93 - General applicability.
2010-07-01
..., diesel-fueled, alcohol-fueled, natural gas-fueled, alcohol dual fuel, and natural gas dual fuel... FUEL ECONOMY AND CARBON-RELATED EXHAUST EMISSIONS OF MOTOR VEHICLES Fuel Economy Regulations for 1977 and Later Model Year Automobiles-Procedures for Calculating Fuel Economy Values § 600.201-93 General...
A general model for membrane-based separation processes
DEFF Research Database (Denmark)
Soni, Vipasha; Abildskov, Jens; Jonsson, Gunnar Eigil;
2009-01-01
behaviour will play an important role. In this paper, modelling of membrane-based processes for separation of gas and liquid mixtures are considered. Two general models, one for membrane-based liquid separation processes (with phase change) and another for membrane-based gas separation are presented...
Energy Technology Data Exchange (ETDEWEB)
Sydzo, Y.; Norio, T.
1984-04-02
It is reported that an improved gas laser system with active medium circulation has been developed. The design of the gas laser is given in block diagram form, and its principle of operation is described in detail. The gaseous active medium flows through the inlet hole to the laser system, and is uniformly dispersed as it flows through the cylindrical diffuser. Thus, a near uniform distribution in the flow velocity of the gas flow in the laser discharge tube is achieved. The gas flow velocity along the edges of the discharge tube exceeds somewhat the flow velocity in the central section, which aids in generating and maintaining a stable and uniform pumping discharge. It is established experimentally that when using the proposed design, the parameters of the output emission from the gas laser are improved significantly. A relationship is given which demonstrates the near linear relationship between the pumping voltage and the output emission power from a gas laser.
2013-02-19
... Energy Regulatory Commission Michigan Consolidated Gas Company, DTE Gas Company, DTE Gas Company; Notice... Docket Nos. PR13-29-000, and PR13-30-000 (not consolidated), Michigan Consolidated Gas Company (MichCon) and DTE Gas Company (DTE Gas) filed to institute a name change to both itself from MichCon to DTE...
2010-03-22
... Energy Regulatory Commission Northern Natural Gas Company, Southern Natural Gas Company, Florida Gas... of Application March 16, 2010. Take notice that on March 5, 2010, Northern Natural Gas Company... other owners, Southern Natural Gas Company, Florida Gas Transmission Company, LLC, Transcontinental...
Gas assisted Mechanical Expression of oilseeds
Willems, P.
2007-01-01
It is the objective of this thesis to show the general applicability of the Gas Assisted Mechanical Expression (GAME) process for recovery of oil from oilseeds with high yields. In this process, the oilseeds are saturated with supercritical CO2 before mechanical pressing. The CO2 displaces part of
Bland-Hawthorn, J.; Reynolds, R. J.
2000-01-01
The interstellar medium (ISM) can be thought of as the galactic atmosphere which fills the space between stars. When clouds within the ISM collapse, stars are born. When the stars die, they return their matter to the surrounding gas. Therefore the ISM plays a vital role in galactic evolution. The medium includes starlight, gas, dust, planets, comets, asteroids, fast moving charged particles (cosmic rays) and magnetic fields. The gas can be further divided into hot, warm and cold components, e...
Energy Technology Data Exchange (ETDEWEB)
Roche, Pat
2011-04-15
Sasol, a South African company, along with the Canadian company Talisman, are looking at gas to liquid process opportunities in North America. Sasol decided to launch a study into the feasibility of gas to liquid (GTL) operation in western Canada, and according to previous studies GTL would need a crude barrel price of $85 or higher combined with a gas price of $4 or less to be economical. Sasol is already operating a GTL plant in Qatar.
Directory of Open Access Journals (Sweden)
Shengfei Qin
2016-10-01
Full Text Available In this paper, the origin of natural gas in the formations of the Changxing–Feixianguan within the Longgang gas field was studied in detail using geochemical methods. The gas discovered has a very high dryness coefficient, yet low ethane and other less heavy hydrocarbons content. Apart from a small amount of N2 and CO2 gasses it generally contains H2S. In the field location, the Changxing–Feixianguan formations itself does not have a hydrocarbon generation potential. Nearing the edge of the Kaijiang-Liangping Trough, there developed the Dalong Formation. However, it also has a very low TOC content in the area of the Longgang gas field, and it cannot act as an effective source rock. The geochemistry of natural gas is much different from the gasses generated by the Silurian and Cambrian source rocks. Therefore, it is impossible that the gas in the Longgang gas field is from the Silurian and Cambrian source rocks. Gas reservoirs generally contain bitumen which is considered a product of crude oil cracking. The carbon isotope fractionation between the bitumen and methane is not distinct, and it indicates that the gas is not directly from oil cracking. The carbon of methane and ethane has isotopically less negative value, which is considered to be in a high-overmature coal-formed gas, mainly from the Longtan Formation coal measures. In comparison to the gas from high overmature stage obtained from the Xujiahe coal measure source rock in the Western Sichuan Depression. The methane in the Longgang gas field has abnormal less negative carbon isotopic value. It is due to the superposition of these two factors together: higher evolution of source rocks and mixing of gas degassing from the water. It is not caused by TSR that most researchers believed at present because the methane carbon isotopic values have no relationship with H2S content.
Gas turbine gas path diagnostics: A review
Directory of Open Access Journals (Sweden)
Fentaye Amare Desalegn
2016-01-01
Full Text Available In this competitive business world one way to increase profitability of a power production unit is to reduce the operation and maintenance expenses. This is possible if the gas turbine availability and reliability is improved using the appropriate maintenance action at the right time. In that case, fault diagnostics is very critical and effective and advanced methods are essential. Gas turbine diagnostics has been studied for the past six decades and several methods are introduced. This paper aims to review and summarise the published literature on gas path diagnostics, giving more emphasis to the recent developments, and identify advantages and limitations of the methods so that beginners in diagnostics can easily be introduced. Towards this end, this paper, identifies various diagnostic methods and point out their pros and cons. Finally, the paper concludes the review along with some recommended future works.
Directory of Open Access Journals (Sweden)
Tomás Correa
2008-12-01
Full Text Available The largest reserves of natural gas worldwide are found in regions far of main cities, being necessary different alternatives to transport the fluid to the consumption cities, such as pipelines, CNG or ships, LNG, depending on distances between producing regions and demanding regions and the producing volumes. Consumption regions have three different markets to naturalgas; residential and commercial, industrial and power generation sector. The residential and commercial is highly seasonal and power generation sector is quite variable depending on increases of temperature during summer time. There are also external issuesthat affect the normal gas flow such as fails on the national system or unexpected interruptions on it, what imply that companies which distribute natural gas should design plans that allow supplying the requirements above mentioned. One plan is using underground natural gas storage with capacities and deliverability rates enough to supply demands. In Colombia there are no laws in this sense but it could be an exploration to discuss different ways to store gas either way as underground natural gas storage or above superficies. Existing basically three different types of underground natural gas storage; depleted reservoirs, salt caverns and aquifers. All ofthem are adequate according to geological characteristics and the needs of the distributors companies of natural gas. This paper is anexploration of technical and economical characteristics of different kind of storages used to store natural gas worldwide.
Directory of Open Access Journals (Sweden)
Godovaniouk V. N.
2011-08-01
Full Text Available The design of a gas speed flow transducer using the coupling of gas speed and heat streams within the transducer itself is proposed. To maintain the heat balance between two thermoresistors under gas stream at different temperatures, it provides energy consumption monitoring. The detailed combined planar technology for the transducer production is presented. The worked-out measurement procedure allows to make measurements in the temperature range. Information enough to organize production of cheap, reliable and precise gas speed flow transducers is given.
Energy Technology Data Exchange (ETDEWEB)
Coltharp, E.D.; Khokhar, M.
1984-09-01
Dubai Petroleum Company has recently installed a computer gas lift surveillance and gas lift gas injection control system in the Fateh and S.W. Fateh Fields located in the southern part of the Arabian Gulf. This system is the fourth generation of the computer control system installed in California in 1971 by Conoco, Inc. This paper describes the advantages and problems in this system to monitor and control the gas lift operation of 116 wells through 30 intelligent remote terminal units (RTU). In addition, this system monitors the condition of critical operational
Energy Technology Data Exchange (ETDEWEB)
NONE
2010-08-15
The ongoing improvement of production technologies has enabled access to unconventional gas resources present in source rocks. Whether Poland is going to see a gas revolution depends chiefly on the geological conditions. At this point it is difficult to estimate the actual size of Poland's shale gas resources and commercialization of shale gas production. First results will be known in the next four or five years, when operators complete the work under exploration and appraisal licences granted to them by the Ministry of the Environment. Polish government is offering licences on exceptionally favourable terms as an incentive for research on unconventional gas resources. Such an approach is driven by the strategic objective of ending Poland's reliance on foreign sources of natural gas in the future. Shale gas will not change Poland's and the region's energy landscape instantaneously. As in the case of all commodity and energy revolutions, changes occur slowly, but shale gas development offers huge opportunities for a permanent shift in the Polish and European energy sectors. Poland stands a chance of becoming fully independent on natural gas imports, and Polish companies - a chance of improving their international standing.
Energy Technology Data Exchange (ETDEWEB)
NONE
1998-10-01
The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. The 1997 data are presented in a sequence that follows natural gas (including supplemental supplies) from its production to its end use. This is followed by tables summarizing natural gas supply and disposition from 1993 to 1997 for each Census Division and each State. Annual historical data are shown at the national level. 27 figs., 109 tabs.
Energy Technology Data Exchange (ETDEWEB)
Biljetina, R.
1994-09-01
One of the constant challenges facing the research community is the identification of technology needs 5 to 15 years from now. A look back into history indicates that the forces driving natural gas research have changed from decade to decade. In the 1970s research was driven by concerns for adequate supply; in the 1980s research was aimed at creating new markets for natural gas. What then are the driving forces for the 1990s? Recent reports from the natural gas industry have helped define a new direction driven primarily by market demand for natural gas. A study prepared by the Interstate Natural Gas Association of America Foundation entitled ``Survey of Natural Research, Development, and Demonstration RD&D Priorities`` indicated that in the 1990s the highest research priority should be for natural gas utilization and that technology development efforts should not only address efficiency and cost, but environmental and regulatory issues as well. This study and others, such as the report by the American Gas Association (A.G.A.) entitled ``Strategic Vision for Natural Gas Through the Year 2000,`` clearly identify the market sectors driving today`s technology development needs. The biggest driver is the power generation market followed by the industrial, transportation, appliance, and gas cooling markets. This is best illustrated by the GRI 1994 Baseline Projection on market growth in various sectors between the year 1992 and 2010. This paper highlights some of the recent technology developments in each one of these sectors.
Stability of the laminar boundary layer for an imperfect gas
Gasperas, G.
The linear perturbation equations are derived for the general case of a compressible imperfect gas characterized by an equation of state utilizing a compressibility factor. The specific case of the Beattie-Bridgeman gas is chosen for calculation. Amplification curves calculated using the Beattie-Bridgeman equation of state for two representative flat plate boundary layers are presented.
East Sichuan to Double Gas Production in 10 Years
Institute of Scientific and Technical Information of China (English)
He Huachun
2001-01-01
@@ The general plan for annual 10-billion-cubic-meter productivity of natural gas in East Sichuan basin has recently passed appraisal by the expert group, indicating that China's current largest onshore natural gas field under production will double its output in a period of more than nine years from now to 2010.
Multiple complementary gas distribution assemblies
Ng, Tuoh-Bin; Melnik, Yuriy; Pang, Lily L; Tuncel, Eda; Nguyen, Son T; Chen, Lu
2016-04-05
In one embodiment, an apparatus includes a first gas distribution assembly that includes a first gas passage for introducing a first process gas into a second gas passage that introduces the first process gas into a processing chamber and a second gas distribution assembly that includes a third gas passage for introducing a second process gas into a fourth gas passage that introduces the second process gas into the processing chamber. The first and second gas distribution assemblies are each adapted to be coupled to at least one chamber wall of the processing chamber. The first gas passage is shaped as a first ring positioned within the processing chamber above the second gas passage that is shaped as a second ring positioned within the processing chamber. The gas distribution assemblies may be designed to have complementary characteristic radial film growth rate profiles.
Detection of Greenhouse-Gas-Induced Climatic Change
Energy Technology Data Exchange (ETDEWEB)
Jones, P.D.; Wigley, T.M.L.
1998-05-26
The objective of this report is to assemble and analyze instrumental climate data and to develop and apply climate models as a basis for (1) detecting greenhouse-gas-induced climatic change, and (2) validation of General Circulation Models.
Lightning protection of oil and gas industrial plants
Energy Technology Data Exchange (ETDEWEB)
Bouquegneau, Christian [Polytechnical University of Mons (Belgium)
2007-07-01
The paper brings some cases and presents the general principles, what the IEC 62305 international standard says, the warning and avoidance and the conclusion about lightning protection of oil and gas industrial plants.
Analysis of Flue Gas Desulfurization (FGD) Processes for Potential Use on Army Coal-Fired Boilers
1980-09-01
Rubber Co. FMC ( Soda Ash Plant ) General Motors General Motors General Motors General Motors General Motors Georgia-Pacific Paper Co. Great...use of alkali, especially caustic (NaOH), also requires increased concern with safety procedures for operating personnel. Limestone flue gas...proven technology was available at the time for SOx removal from stack gas at coal burning heating plants . This meant that coal burning units either
Energy Technology Data Exchange (ETDEWEB)
Turner, R. [TransCanada Transmission, Calgary, AB (Canada)
2004-07-01
This presentation reviewed natural gas supply and demand issues facing Ontario and outlined TransCanada's role as a key player in Ontario's energy industry. TransCanada's gas transmission assets include 39,000 km of wholly owned pipelines from British Columbia to Atlantic Canada that carry 11 Bcf of gas per day. In addition, TransCanada operates 29 power generating plants, of which 6 are in Ontario. The company is also involved the proposed Mackenzie Valley and Alaska pipeline. A map illustrating Ontario and Quebec operations was included along with graphs depicting the 2004 base case for North American gas demand by region. Historical and forecasted gas demand by end use sector in Ontario and Quebec was also illustrated. A chart of North American gas supply indicates that new supply is needed to meet energy demands. Production forecasts for Western Canada for conventional and unconventional reserves indicates that by 2015, unconventional reserves such as coalbed methane (CBM) will make up a larger portion of the production mix. A map indicating existing and proposed import terminals along the Atlantic and Pacific coasts for liquefied natural gas (LNG) was included. The challenges facing the North American gas market include price volatility, the need to update energy policies, the need to improve regulatory efficiency, and aligning the interests of market participants. It was concluded that although natural gas from Western Canada will continue to be a stable supply source for many years, the natural gas market in North America is seeking new supply in frontier gas, LNG and CBM to meeting growing demand. 1 tab., 11 figs.
Gas drainage technology of high gas and thick coal seam
Institute of Scientific and Technical Information of China (English)
HE Tian-cai; LI Hai-gui; ZHANG Hai-jun
2009-01-01
Gas drainage in Jincheng Mining Group Co., Ltd. was introduced briefly and the importance of gas drainage in gas control was analyzed. Combined with coal-bed gas oc-currence and gas emission, the double system of gas drainage was optimized and a pro-gressive gas drainage model was experimented on. For guaranteed drainage, excavation and mining and realization of safety production and reasonable exploitation of gas in coal seams, many drainage methods were adopted to solve the gas problem of the working face.
Energy Technology Data Exchange (ETDEWEB)
Koch, G.
1995-09-18
The state of Alberta`s natural gas resources were reviewed and according to certain groups of experts reserves and resources were found to be less plentiful than generally believed. The Canadian Association of Petroleum Producers (CAPP) also reported that gas reserves in non-frontier areas declined by 1.8% lat year, to 67.4 trillion cubic feet. It was estimated that this supply would last for 13 years. The National Energy Board (NEB) indicated that thousands of Alberta`s unconnected pools may not be economical to develop. The CAPP annual reserves report also indicated that average gas pools found in recent times were only one quarter of the size of gas pools found before 1980. It was argued by this same group of experts that low gas prices, particularly for Alberta exports, have made drilling uneconomical, while others maintained that price fluctuations must be accepted as part of selling a commodity that is marketed world-wide. Ed Wolf, an independent geologist, estimated that gas prices,factoring in environmental costs, should be increased to $4 per mcf to justify exporting Canadian natural gas. However, others have argued that reserve figures have been underestimated. As proof of that they point to the fact that there is no shortage of investment capital; exploration and production activities, funded by investment, would not continue if natural gas production were not cost-effective. The Ziff Energy Group estimated that discovered and frontier reserves total 426 tcf, or 65 years` supply, excluding tight gas from low porosity formations which have been estimated to provide up to 300 years of supply at current levels of demand. As well, new technologies have improved the industry`s ability to find new reserves. The debate between economic nationalists and free marketeers continues.
... Physician Resources Professions Site Index A-Z General Nuclear Medicine Nuclear medicine imaging uses small amounts of ... limitations of General Nuclear Medicine? What is General Nuclear Medicine? Nuclear medicine is a branch of medical ...
... Physician Resources Professions Site Index A-Z General Ultrasound Ultrasound imaging uses sound waves to produce pictures ... limitations of General Ultrasound Imaging? What is General Ultrasound Imaging? Ultrasound is safe and painless, and produces ...
California Department of Resources — We undertook creating the first ever seamless statewide General Plan map for California. All county general plans and many city general plans were integrated into 1...
California Department of Resources — We undertook creating the first ever seamless statewide General Plan map for California. All county general plans and many city general plans were integrated into 1...
California Department of Resources — We undertook creating the first ever seamless statewide General Plan map for California. All county general plans and many city general plans were integrated into 1...
Directory of Open Access Journals (Sweden)
Nazmi Oruç
2012-12-01
şehir temiz hava planı (2011-2014 hazırlanmıştır. Partikül Madde ve SO2 yanında NO2,O3 ve PAH gibi kirleticilerin ve ulaşım araçlarının neden olduğu kirliliğin de irdelendiği bu raporda, Eskişehir için ulusal yasal sınır değerleri zorlayan bir durum söz konusu olmasa da geniş ölçekte Avrupa Birliği ve Dünya Sağlık Örgütü (DSÖ gibi kuruluşların oluşturmuş olduğu standartların üzerinde değerlere rastlandığı kaydedilmektedir. Hava kirliliğinin önlenmesi amacıyla doğal gaz kullanımına ilk kez Eskişehir Organize Sanayi Bölgesinde (EOSB Botaş bünyesinde 1990 yılında başlanılmış daha sonra bu hizmet özelleştirme kapsamı içerisinde 2004 yılında Eskişehir Doğal Gaz Dağıtım A.Ş. (ESGAZ firmasına devredilmiştir. ESGAZ, Büyükşehir Belediyesi mücavir alanlarda yer alan imara açık tüm cadde ve sokaklara doğal gaz hizmeti vermekte olup 2004 yılında devir alınan 107.000 bağımsız birim sayısını 2011 yılı sonu itibariyle 300.000’e çıkartmıştır. EOSB bölgesi hariç evsel ve şehir içi sanayi tüketimi de 2005 yılında 211.756.888 m3 iken, 2011 yılında 348.974.147 m3’e çıkmıştır. Tüm bu olumlu gelişmelere karşın doğal gaz alt yapısı bulunan bazı semt ve apartmanlarda günümüzde de ithal ve yerli kömür kullanılması zaman zaman hava kirliliğine neden olmaktadır. İlk aşamada kent merkezinde özellikle kış aylarında kömür yerine tamamen doğal gaza geçilmesi ve ulaşım kaynaklı hava kirliğinin azaltılması için gereken önlemlerin alınması önerilmiştir. History of Air Pollution and Natural Gas Usage in Eskişehir: A General Review The aim of this study is to investigate the use of natural gas and air pollution levels in Eskişehir City Center in the last 30 years. Air pollution has been phenomena in Eskişehir since the beginning of 1980s, due to the use of low quality coal, unplanned and irregular urbanization and negative climate factors. First air
[Gas gangrene: a military disease?].
Pailler, J L; Labeeu, F
1986-01-01
Gas gangrene is a general toxi-infection, which is mostly the result of a contamination of the muscles from traumatic or post-operative origin. Muscular necrosis expands very quickly, causes mutilations, hits several organs and leads to shock. The spontaneous evolution is mostly mortal within a couple of hours. For a long time it was considered to be a typical military disease: during World War I some 100,000 German soldiers lost their lives as a direct result. It represented then 10 to 12% of all deads of wounds. This mortality rate decreased between 0.3 and 1.5% during World War II and to 0.016% during the Vietnam WAr. Although gas gangrene is no longer a typical military disease, the holy principles of war surgery must be respected. All war wounds, and in particular those caused by high velocity missiles are contaminated, a.o. by clostridium spores. An immediate suture of those wounds, through which necrotized tissue is covered (an ideal anaerobic environment), furthers the development of gas gangrene. The only prevention consists of debriding those wounds, leaving them opened, followed by a delayed primary suture between the 4th and 7th day after the debridement. Not properly treated will gas gangrene always be mortal. In some instances, an emergency amputation will be the only way to save the patient's life. Antibiotherapy, hyperbaric oxygenotherapy and most of all surgery from the medical triade which is imperative to treat this disease. Thanks to these measures, the mortality rate decreased from 70% before 1960 to 41%. Nonetheless the most important act remains the early, complete, rational and rigorous debridement of the wounds. Far from being an obsolete attitude, this is one of humility, wisdom ... and with future prospects.
Comparison of dark energy models after Planck 2015
Energy Technology Data Exchange (ETDEWEB)
Xu, Yue-Yao [Northeastern University, Department of Physics, College of Sciences, Shenyang (China); Zhang, Xin [Northeastern University, Department of Physics, College of Sciences, Shenyang (China); Peking University, Center for High Energy Physics, Beijing (China)
2016-11-15
We make a comparison for ten typical, popular dark energy models according to their capabilities of fitting the current observational data. The observational data we use in this work include the JLA sample of type Ia supernovae observation, the Planck 2015 distance priors of cosmic microwave background observation, the baryon acoustic oscillations measurements, and the direct measurement of the Hubble constant. Since the models have different numbers of parameters, in order to make a fair comparison, we employ the Akaike and Bayesian information criteria to assess the worth of the models. The analysis results show that, according to the capability of explaining observations, the cosmological constant model is still the best one among all the dark energy models. The generalized Chaplygin gas model, the constant w model, and the α dark energy model are worse than the cosmological constant model, but still are good models compared to others. The holographic dark energy model, the new generalized Chaplygin gas model, and the Chevalliear-Polarski-Linder model can still fit the current observations well, but from an economically feasible perspective, they are not so good. The new agegraphic dark energy model, the Dvali-Gabadadze-Porrati model, and the Ricci dark energy model are excluded by the current observations. (orig.)
Comparison of dark energy models after Planck 2015
Xu, Yue-Yao; Zhang, Xin
2016-11-01
We make a comparison for ten typical, popular dark energy models according to their capabilities of fitting the current observational data. The observational data we use in this work include the JLA sample of type Ia supernovae observation, the Planck 2015 distance priors of cosmic microwave background observation, the baryon acoustic oscillations measurements, and the direct measurement of the Hubble constant. Since the models have different numbers of parameters, in order to make a fair comparison, we employ the Akaike and Bayesian information criteria to assess the worth of the models. The analysis results show that, according to the capability of explaining observations, the cosmological constant model is still the best one among all the dark energy models. The generalized Chaplygin gas model, the constant w model, and the α dark energy model are worse than the cosmological constant model, but still are good models compared to others. The holographic dark energy model, the new generalized Chaplygin gas model, and the Chevalliear-Polarski-Linder model can still fit the current observations well, but from an economically feasible perspective, they are not so good. The new agegraphic dark energy model, the Dvali-Gabadadze-Porrati model, and the Ricci dark energy model are excluded by the current observations.
Energy Technology Data Exchange (ETDEWEB)
Krikke, R. [ed.
2000-03-01
In this first part of a new series experts in the field of the natural gas market in the Netherlands are interviewed about their opinion on the consequences of and developments after the new Dutch Natural Gas Law ('Gaswet') has come into effect. In this article the general manager of the natural gas trading company Gasunie answers questions on the natural gas market and the position of Gasunie in that market. He also expresses his personal interest in domotics.
Institute of Scientific and Technical Information of China (English)
无
2013-01-01
outlook weekly may 20 with the increase of green gas emissions， combating climate change has become a common concern across the world. upping the levels of natural gas in terms of global energy consumption is essential to realize a low-carbon future. for china，
Generalized Probability Functions
Directory of Open Access Journals (Sweden)
Alexandre Souto Martinez
2009-01-01
Full Text Available From the integration of nonsymmetrical hyperboles, a one-parameter generalization of the logarithmic function is obtained. Inverting this function, one obtains the generalized exponential function. Motivated by the mathematical curiosity, we show that these generalized functions are suitable to generalize some probability density functions (pdfs. A very reliable rank distribution can be conveniently described by the generalized exponential function. Finally, we turn the attention to the generalization of one- and two-tail stretched exponential functions. We obtain, as particular cases, the generalized error function, the Zipf-Mandelbrot pdf, the generalized Gaussian and Laplace pdf. Their cumulative functions and moments were also obtained analytically.
Bravo, Jose Luis [Houston, TX; Harvey, III, Albert Destrehan; Vinegar, Harold J [Bellaire, TX
2012-04-03
Systems and methods of treating a gas stream are described. A method of treating a gas stream includes cryogenically separating a first gas stream to form a second gas stream and a third stream. The third stream is cryogenically contacted with a carbon dioxide stream to form a fourth and fifth stream. A majority of the second gas stream includes methane and/or molecular hydrogen. A majority of the third stream includes one or more carbon oxides, hydrocarbons having a carbon number of at least 2, one or more sulfur compounds, or mixtures thereof. A majority of the fourth stream includes one or more of the carbon oxides and hydrocarbons having a carbon number of at least 2. A majority of the fifth stream includes hydrocarbons having a carbon number of at least 3 and one or more of the sulfur compounds.
Thermoacoustic natural gas liquefier
Energy Technology Data Exchange (ETDEWEB)
Swift, G.; Gardner, D.; Hayden, M.; Radebaugh, R. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Wollan, J. [Cryenco, Inc. (United States)
1996-07-01
This is the final report of a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project sought to develop a natural-gas-powered natural-gas liquefier that has absolutely no moving parts and requires no electrical power. It should have high efficiency, remarkable reliability, and low cost. The thermoacoustic natural-gas liquefier (TANGL) is based on our recent invention of the first no-moving-parts cryogenic refrigerator. In short, our invention uses acoustic phenomena to produce refrigeration from heat, with no moving parts. The required apparatus comprises nothing more than heat exchangers and pipes, made of common materials, without exacting tolerances. Its initial experimental success in a small size lead us to propose a more ambitious application: large-energy liquefaction of natural gas, using combustion of natural gas as the energy source. TANGL was designed to be maintenance-free, inexpensive, portable, and environmentally benign.
Energy Technology Data Exchange (ETDEWEB)
Bravo, Jose Luis [Houston, TX; Harvey, III, Albert Destrehan (Kingwood, TX); Vinegar, Harold J [Bellaire, TX
2012-04-03
Systems and methods of treating a gas stream are described. A method of treating a gas stream includes cryogenically separating a first gas stream to form a second gas stream and a third stream. The third stream is cryogenically contacted with a carbon dioxide stream to form a fourth and fifth stream. A majority of the second gas stream includes methane and/or molecular hydrogen. A majority of the third stream includes one or more carbon oxides, hydrocarbons having a carbon number of at least 2, one or more sulfur compounds, or mixtures thereof. A majority of the fourth stream includes one or more of the carbon oxides and hydrocarbons having a carbon number of at least 2. A majority of the fifth stream includes hydrocarbons having a carbon number of at least 3 and one or more of the sulfur compounds.
Energy Technology Data Exchange (ETDEWEB)
Boorstin, D.
1975-11-07
Curtailments of gas supplies in the winter of 1975-76 were estimated to be 2.9 trillion cubic feet or 15 percent of demand, which represented a 45 percent increase over curtailments in 1974-75. The scarcities are discussed under the following topics: probable dimensions of natural gas curtailment; effects of winter shortages, possibility of relief; debate over attempt to remove price ceilings; and charges of gas withholding and underreporting. The history of gas use and regulation is reviewed under the following: from unwanted oil by-product to useful fuel; development of regulation and extent of control; and policy change at the Federal Power Commission. The outlook for overcoming the shortage is discussed under the following: revised estimates of undiscovered resources; rival proposals to make Alaskan gas available; and continuing search for substitute energy sources. 37 references. (MCW)
Understanding vented gas explosions
Energy Technology Data Exchange (ETDEWEB)
Lautkaski, R. [VTT Energy, Espoo (Finland). Energy Systems
1997-12-31
The report is an introduction to vented gas explosions for nonspecialists, particularly designers of plants for flammable gases and liquids. The phenomena leading to pressure generation in vented gas explosions in empty and congested rooms are reviewed. The four peak model of vented gas explosions is presented with simple methods to predict the values of the individual peaks. Experimental data on the external explosion of dust and gas explosions is discussed. The empirical equation relating the internal and external peak pressures in vented dust explosions is shown to be valid for gas explosion tests in 30 m{sup 3} and 550 m{sup 3} chambers. However, the difficulty of predicting the internal peak pressure in large chambers remains. Methods of explosion relief panel design and principles of vent and equipment layout to reduce explosion overpressures are reviewed. (orig.) 65 refs.
Gas Storage Technology Consortium
Energy Technology Data Exchange (ETDEWEB)
Joel Morrison
2005-09-14
Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services, and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is critical in meeting the needs of these new markets. In order to address the gas storage needs of the natural gas industry, an industry driven consortium was created--the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance operational flexibility and deliverability of the Nation's gas storage system, and provide a cost effective, safe, and reliable supply of natural gas to meet domestic demand. This report addresses the activities for the quarterly period of April 1, 2005 through June 30, 2005. During this time period efforts were directed toward (1) GSTC administration changes, (2) participating in the American Gas Association Operations Conference and Biennial Exhibition, (3) issuing a Request for Proposals (RFP) for proposal solicitation for funding, and (4) organizing the proposal selection meeting.
Energy Technology Data Exchange (ETDEWEB)
Mandil, C. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France); Chabrelie, M.F. [Cedigaz, 92 - Rueil Malmaison (France); Streicher, C. [Prosernat, 92 - Paris la Defense (France)] [and others
2003-07-01
New developments in the area of gas treatment will be to a large extent driven by the need to find appropriate solutions to the fundamental need of sustainable development. New gas treatment processes are developed with the aim to minimise contaminant emissions and meet most stringent environmental specifications. A new major challenge for the industry will be to implement new cost effective technologies for reducing CO{sub 2} emissions. Industry has also to minimise its costs, and therefore, in order to ensure at the same time a better protection of the environment and a better safety, it is necessary to innovate. The purpose of this seminar is precisely to identify better the innovations which are required in the area of gas treatment. These proceedings comprise 8 papers and a summary of the contributions to a round-table discussion dealing with the options for CO{sub 2} capture and sequestration. The presentations treat of: the future prospects for the gas industry (M.F. Chabrelie, Cedigaz); the solutions for offshore gas treatment (C. Streicher, Prosernat); gas treatment with membranes (H. Meyer, GTI); the Axens Multibed{sub TM} technology for natural gas treatment (G. Jochem, Axens); the potentials and applications for the Propure co-current contactors (F.P. Nilsen, ProPure); the production of very-sour and super-sour large gas reserves: the new challenges (F. Lallemand, TotalFinaElf); Hybrisol, a new gas treatment process for sour natural gases (F. Lecomte, IFP); and the conception and building of large acid-gas removal units (J. Castel, Technip-Coflexip). (J.S.)
Regulation of gas infrastructure expansion
De Joode, J.
2012-01-01
The topic of this dissertation is the regulation of gas infrastructure expansion in the European Union (EU). While the gas market has been liberalised, the gas infrastructure has largely remained in the regulated domain. However, not necessarily all gas infrastructure facilities – such as gas storag
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.
Catalytic hot gas cleaning of gasification gas
Energy Technology Data Exchange (ETDEWEB)
Simell, P. [VTT Energy, Espoo (Finland). Energy Production Technologies
1997-12-31
The aim of this work was to study the catalytic cleaning of gasification gas from tars and ammonia. In addition, factors influencing catalytic activity in industrial applications were studied, as well as the effects of different operation conditions and limits. Also the catalytic reactions of tar and ammonia with gasification gas components were studied. The activities of different catalyst materials were measured with laboratory-scale reactors fed by slip streams taken from updraft and fluid bed gasifiers. Carbonate rocks and nickel catalysts proved to be active tar decomposing catalysts. Ammonia decomposition was in turn facilitated by nickel catalysts and iron materials like iron sinter and iron dolomite. Temperatures over 850 deg C were required at 2000{sup -1} space velocity at ambient pressure to achieve almost complete conversions. During catalytic reactions H{sub 2} and CO were formed and H{sub 2}O was consumed in addition to decomposing hydrocarbons and ammonia. Equilibrium gas composition was almost achieved with nickel catalysts at 900 deg C. No deactivation by H{sub 2}S or carbon took place in these conditions. Catalyst blocking by particulates was avoided by using a monolith type of catalyst. The apparent first order kinetic parameters were determined for the most active materials. The activities of dolomite, nickel catalyst and reference materials were measured in different gas atmospheres using laboratory apparatus. This consisted of nitrogen carrier, toluene as tar model compound, ammonia and one of the components H{sub 2}, H{sub 2}O, CO, CO{sub 2}, CO{sub 2}+H{sub 2}O or CO+CO{sub 2}. Also synthetic gasification gas was used. With the dolomite and nickel catalyst the highest toluene decomposition rates were measured with CO{sub 2} and H{sub 2}O. In gasification gas, however, the rate was retarded due to inhibition by reaction products (CO, H{sub 2}, CO{sub 2}). Tar decomposition over dolomite was modelled by benzene reactions with CO{sub 2}, H
Gas expulsion in massive star clusters?. Constraints from observations of young and gas-free objects
Krause, Martin G. H.; Charbonnel, Corinne; Bastian, Nate; Diehl, Roland
2016-03-01
Context. Gas expulsion is a central concept in some of the models for multiple populations and the light-element anti-correlations in globular clusters. If the star formation efficiency was around 30 per cent and the gas expulsion happened on the crossing timescale, this process could preferentially expel stars born with the chemical composition of the proto-cluster gas, while stars with special composition born in the centre would remain bound. Recently, a sample of extragalactic, gas-free, young massive clusters has been identified that has the potential to test the conditions for gas expulsion. Aims: We investigate the conditions required for residual gas expulsion on the crossing timescale. We consider a standard initial mass function and different models for the energy production in the cluster: metallicity-dependent stellar winds, radiation, supernovae and more energetic events, such as hypernovae, which are related to gamma ray bursts. The latter may be more energetic than supernovae by up to two orders of magnitude. Methods: We computed a large number of thin-shell models for the gas dynamics, and calculated whether the Rayleigh-Taylor instability is able to disrupt the shell before it reaches the escape speed. Results: We show that the success of gas expulsion depends on the compactness index of a star cluster C5 ≡ (M∗/ 105 M⊙)/(rh/ pc), with initial stellar mass M∗ and half-mass radius rh. For given C5, a certain critical, local star formation efficiency is required to remove the rest of the gas. Common stellar feedback processes may not lead to gas expulsion with significant loss of stars above C5 ≈ 1. Considering pulsar winds and hypernovae, the limit increases to C5 ≈ 30. If successful, gas expulsion generally takes place on the crossing timescale. Some observed young massive clusters have 1 age. Conclusions: Globular clusters should initially have C5 ≲ 100, if the gas expulsion paradigm was correct. Early gas expulsion, which is
Energy Technology Data Exchange (ETDEWEB)
Stonehouse, D.
2001-04-01
Despite completing 8,900 gas wells in year 2000, the deliverability of natural gas out of the Western Canadian Sedimentary Basin (WCSB) was stagnant which has left many analysts wondering whether the basin has reached its limit. It also leaves many wondering if gas producers will be able to meet the strong demand for natural gas in the future. Nearly all new electrical generation being built in the U.S. is gas-based due to strict new environmental standards limiting the growth in hydro and coal-powered generation. Any future coal plants will use gasification technology and combined cycle turbines. Combined cycle turbines developed by Boeing and Lockheed are more efficient than combustion turbines, making gas more competitive with fuel alternatives. The lack of growth in natural gas supply has left storage levels near record lows. Demand is expected to increase in 2001 by 3.2 per cent to 23 trillion cubic feet in the U.S. Longer term, major new reserves must be brought on stream to meet this demand. It was noted that the easy discoveries within the WCSB have been made. The new plays are smaller, more technically complex and expensive which suggests that more investment is needed in training geologists, geophysicists and petroleum engineers to find new reserves. The Canadian Energy Research Institute agrees that there is enough gas in Alberta and British Columbia to meet current demands but efforts must shift towards drilling in the foothills front and northwest regions of Alberta to increase deliverability. Brief notes on several gas finds by various oil and gas companies in the area were presented. The article also discussed the huge untapped potential of northern reserves. Analysts have noted 44 Tcf of proven reserve, with a potential of 165 Tcf. In addition, new pipelines from the Alaskan North Slope and the Mackenzie Delta could transport nearly 2 Tcf annually to market. Wells drilled by Chevron and Paramount at Fort Liard in 1999 initially flowed at rates up to
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.
Statistical estimation of loads from gas explosions
Energy Technology Data Exchange (ETDEWEB)
Hoeiset, Stian
1998-12-31
In the design of structures in the offshore and process industries, the possibility of a gas explosion must always be considered. The main uncertainties in computerized simulation of gas explosions are the assumptions of the gas cloud, the location of the ignition point and the properties of the simulator itself. This thesis quantifies the levels of these uncertainties by performing a large number of simulations on three offshore modules and one onshore plant. It is found that (1) there is an approximate linear relation between pressure and gas volume, (2) it may be possible to find a linear relation between pressure and impulse, (3) there is an inverse relation between pressure and duration, (4) the response of offshore structures exposed to gas explosions are rarely in the impulsive regime, (5) loading rates vary widely in magnitude, (6) an assumption of a triangular explosion pulse is often correct, (7) louvres increase pressure, impulse and duration of an explosion. The effect of ignition point location is studied in detail. It is possible to derive an ignition point uncertainty load factor that shows predictable behaviour by generalizing the non-parametric properties of the explosion pressure. A model for taking into account the uncertainties regarding gas volume, ignition point location and simulator imperfectness is proposed. The model is intended to produce a characteristic load for structural design. 68 refs., 51 figs., 36 tabs.
Full Text Available ... attached to a probe and inserted into a natural opening in the body. These exams include: Transesophageal ... Imaging? Ultrasound waves are disrupted by air or gas; therefore ultrasound is not an ideal imaging technique ...
Institute of Scientific and Technical Information of China (English)
丁夏畦; 罗佩珠
2004-01-01
In this paper the authors introduce some new ideas on generalized numbers and generalized weak functions. They prove that the product of any two weak functions is a generalized weak function. So in particular they solve the problem of the multiplication of two generalized functions.
Generalized holomorphic structures
Wang, Yicao
2014-12-01
We define the notion of generalized holomorphic principal bundles and establish that their associated vector bundles of holomorphic representations are generalized holomorphic vector bundles defined by M. Gualtieri. Motivated by our definition, several examples of generalized holomorphic structures are constructed. A reduction theorem of generalized holomorphic structures is also included.
How general is general information construct?
Directory of Open Access Journals (Sweden)
Predrag Zarevski
2005-04-01
Full Text Available There is a small number of constructs in the field of differential psychology that have raised so much debate between psychologists and professionals in related disciplines as is the case of general (verbal information construct. It seemed reasonable to test the validity of this construct measured with general information test in comparison with other measures of knowledge (cultural knowledge, vocabulary, knowledge of the most recent events, foreign language knowledge, and a standard verbal type g test. A sample of 376 candidates for state services was tested in a selection situation. Three analyses were conducted to determine the position of general information test in the space of other verbal competency measures. The first analysis questioned latent structure of the space of four tests having the same format and asking about the knowledge of international terms, general culture, knowledge of most recent events, and general information. The second analysis included the g-factor intelligence test so to see how the above described structure changes when this new test is introduced. The third analysis introduced an English language test. In all of the three component analyses only one eigenvalue was larger than 1 and it explained between 52 and 64% of variance. In all analyses general information test had the highest projection on the only significant latent dimension of these cognitive spaces. In other words, it can be concluded that the construct of general information is in the center of this hyperconus. That is why we consider measurement of general information knowledge, as well as the construct itself, to be an important question in psychological diagnostics. Thus, it is important to go further with the investigation of this construct because it does not seem that it is named general information by accident.
Interstellar gas in the Gum Nebula
Wallerstein, G.; Jenkins, E. B.; Silk, J.
1980-01-01
A survey of the interstellar gas near the Gum Nebula by optical observation of 67 stars at Ca II, 42 stars at Na I, and 14 stars in the UV with the Copernicus satellite provided radial velocities and column densities for all resolved absorption components. Velocity dispersions for gas in the Gum Nebula are not significantly larger than in the general interstellar medium; the ionization structure is predominantly that of an H II region with moderately high ionization. Denser, more highly ionized clouds are concentrated toward the Gum Nebula; these clouds do not show the anomalously high ionization observed in the Vela remnant clouds.
AGT 100 automotive gas turbine system development
Helms, H. E. G.
1982-01-01
General Motors is developing an automotive gas turbine system that can be an alternate powerplant for future automobiles. Work sponsored by DOE and administered by NASA Lewis Research Center is emphasizing small component aerodynamics and high-temperature structural ceramics. Reliability requirements of the AGT 100 turbine system include chemical and structural ceramic component stability in the gas turbine environment. The power train system, its configuration and schedule are presented, and its performance tested. The aerodynamic component development is reviewed with discussions on the compressor, turbine, regenerator, interturbine duct and scroll, and combustor. Ceramic component development is also reviewed, and production cost and required capital investment are taken into consideration.
Introduction to general and generalized linear models
Madsen, Henrik
2010-01-01
IntroductionExamples of types of data Motivating examples A first view on the modelsThe Likelihood PrincipleIntroduction Point estimation theory The likelihood function The score function The information matrix Alternative parameterizations of the likelihood The maximum likelihood estimate (MLE) Distribution of the ML estimator Generalized loss-function and deviance Quadratic approximation of the log-likelihood Likelihood ratio tests Successive testing in hypothesis chains Dealing with nuisance parameters General Linear ModelsIntroduction The multivariate normal distribution General linear mod
Energy Technology Data Exchange (ETDEWEB)
Graf, Frank [DVGW-Forschungsstelle am KIT, Karlsruhe (Germany); Groeschl, Frank; Wetzel, Uwe [DVGW, Bonn (Germany); Heikrodt, Klaus [Hochschule Ostwestfalen-Lippe, Lemgo (Germany); Krause, Hartmut [DBI Gastechnologisches Institut, An-Institut der TU Bergakademie, Freiberg (Germany); Beestermoeller, Christina; Witschen, Bernhard [Team Consult G.P.E. GmbH, Berlin (Germany); Albus, Rolf; Burmeister, Frank [Gas- und Waerme-Institut Essen e.V., Essen (Germany)
2015-07-01
The reform of the EEG in Germany, a positive global development in natural gas, the decline in oil prices, questions about the security of supply in Europe, and not least the effect of the decision by E.on at the end of 2014 have moved the gas industry. Gas has the lowest CO{sub 2} emissions of fossil fuels. Flexibility, storability, useful for networks and the diversity in the application make it an ideal partner for renewable energy. However, these complementary properties are valued at wind and photovoltaics internationally and nationally different. The situation in the gas power plants remains tense. LNG - liquefied natural gas - is on the rise. [German] Die Reform des EEG in Deutschland, eine positive Entwicklung beim Gas weltweit, der Verfall der Oelpreises, Fragen zur Versorgungssicherheit in Europa und nicht zuletzt die Auswirkung der Entscheidung von E.on Ende 2014 haben die Gaswirtschaft bewegt. Gas weist die geringsten CO{sub 2}-Emissioen der fossilen Energietraeger auf. Flexibilitaet, Speicherbarkeit, Netzdienlichkeit sowie die Vielfalt in der Anwendung machen es zum idealen Partner der erneuerbaren Energien. Allerdings werden diese komplementaeren Eigenschaften zu Wind und Photovoltaik international und national unterschiedlich bewertet. Die Lage bei den Gaskraftwerken bleibt weiter angespannt. LNG - verfluessigtes Erdgas - ist auf dem Vormarsch.
Gas Storage Technology Consortium
Energy Technology Data Exchange (ETDEWEB)
Joel L. Morrison; Sharon L. Elder
2007-06-30
Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is crucial in meeting the needs of these new markets. To address the gas storage needs of the natural gas industry, an industry-driven consortium was created--the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance the operational flexibility and deliverability of the nation's gas storage system, and provide a cost-effective, safe, and reliable supply of natural gas to meet domestic demand. This report addresses the activities for the quarterly period of April 1, 2007 through June 30, 2007. Key activities during this time period included: (1) Organizing and hosting the 2007 GSTC Spring Meeting; (2) Identifying the 2007 GSTC projects, issuing award or declination letters, and begin drafting subcontracts; (3) 2007 project mentoring teams identified; (4) New NETL Project Manager; (5) Preliminary planning for the 2007 GSTC Fall Meeting; (6) Collecting and compiling the 2005 GSTC project final reports; and (7) Outreach and communications.
Gas Storage Technology Consortium
Energy Technology Data Exchange (ETDEWEB)
Joel L. Morrison; Sharon L. Elder
2007-03-31
Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is crucial in meeting the needs of these new markets. To address the gas storage needs of the natural gas industry, an industry-driven consortium was created - the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance the operational flexibility and deliverability of the nation's gas storage system, and provide a cost-effective, safe, and reliable supply of natural gas to meet domestic demand. This report addresses the activities for the quarterly period of January1, 2007 through March 31, 2007. Key activities during this time period included: {lg_bullet} Drafting and distributing the 2007 RFP; {lg_bullet} Identifying and securing a meeting site for the GSTC 2007 Spring Proposal Meeting; {lg_bullet} Scheduling and participating in two (2) project mentoring conference calls; {lg_bullet} Conducting elections for four Executive Council seats; {lg_bullet} Collecting and compiling the 2005 GSTC Final Project Reports; and {lg_bullet} Outreach and communications.
Gas Storage Technology Consortium
Energy Technology Data Exchange (ETDEWEB)
Joel L. Morrison; Sharon L. Elder
2006-05-10
Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services, and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is critical in meeting the needs of these new markets. In order to address the gas storage needs of the natural gas industry, an industry-driven consortium was created--the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance operational flexibility and deliverability of the Nation's gas storage system, and provide a cost effective, safe, and reliable supply of natural gas to meet domestic demand. This report addresses the activities for the quarterly period of January 1, 2006 through March 31, 2006. Activities during this time period were: (1) Organize and host the 2006 Spring Meeting in San Diego, CA on February 21-22, 2006; (2) Award 8 projects for co-funding by GSTC for 2006; (3) New members recruitment; and (4) Improving communications.
Energy Technology Data Exchange (ETDEWEB)
1985-02-01
Three separate emplacement concepts could explain the occurrence of gas at extreme depths: abiogenesis (a primordial, nonbiologic origin source); subducted, organic-origin gas (involving the deep, tectonic subduction emplacement of hydrocarbon-generating ocean sediments); and deep sedimentary basin gas (the more conventional emplacement of sedimentary rocks by deep downwarping of the Earth's crust). Of these concepts, Deep Source Gas research focuses on the subducted, organic-origin concept. The purpose of Deep Source Gas research is to verify natural gas arising from depths in excess of 30,000 feet, to relate these occurrences to conceptual models, to define the limits of target areas, to quantify the resource, and to determine the significance of the gas to the nation's reserves. The research emphasizes an Earth science study (geology, geochemistry, and geophysics) of the Cordilleran Geologic Province of western North America. This area is considered a prospective source largely because of known and suspected plate tectonic structures and their youthful emplacement, which increase the likelihood of a timely entrapment of deep-source generated hydrocarbons. Detailed geochemical studies indicate that the deep-source-gas generating capacity of the Aleutian Trench area of southern Alaska is high. Furthermore, geophysical studies show that an apparent fossil subduction zone exists in western Washington. This zone appears to have very thick sedimentary rock units, the existence of which will be evaluated through a more detailed seismic study and possibly through drilling activities. Structural observations made in the northern Brooks Range and central Alaskan Range indicate that overthrusting and compressional features may serve as large-scale target areas for deep source gas generation and occurrence. 12 figures, 2 tables.
Gas: A Neglected Phase in Remediation of Metals and Radionuclides
Energy Technology Data Exchange (ETDEWEB)
Denham, Miles E.; Looney, Brian B
2005-09-28
The gas phase is generally ignored in remediation of metals and radionuclides because it is assumed that there is no efficient way to exploit it. In the literal sense, all remediations involve the gas phase because this phase is linked to the liquid and solid phases by vapor pressure and thermodynamic relationships. Remediation methods that specifically use the gas phase as a central feature have primarily targeted volatile organic contaminants, not metals and radionuclides. Unlike many organic contaminants, the vapor pressure and Henry's Law constants of metals and radionuclides are not generally conducive to direct air stripping of dissolved contaminants. Nevertheless, the gas phase can play an important role in remediation of inorganic contaminants and provide opportunities for efficient, cost effective remediation. The objective here is to explore ways in which manipulation of the gas phase can be used to facilitate remediation of metals and radionuclides.
Proceedings of the natural gas research and development contractors review meeting
Energy Technology Data Exchange (ETDEWEB)
Malone, R.D.; Shoemaker, H.D.; Byrer, C.W. (eds.)
1990-11-01
The purpose of this meeting was to present results of the research in the DOE-sponsored Natural Gas Program, and simultaneously to provide a forum for real-time technology transfer, to the active research community, to the interested public, and to the natural gas industry, who are the primary users of this technology. The current research focus is to expand the base of near-term and mid-term economic gas resources through research activities in Eastern Tight Gas, Western Tight Gas, Secondary Gas Recovery (increased recovery of gas from mature fields); to enhance utilization, particularly of remote gas resources through research in Natural Gas to Liquids Conversion; and to develop additional, long term, potential gas resources through research in Gas Hydrates and Deep Gas. With the increased national emphasis on the use of natural gas, this forum has been expanded to include summaries of DOE-sponsored research in energy-related programs and perspectives on the importance of gas to future world energy. Thirty-two papers and fourteen poster presentations were given in seven formal, and one informal, sessions: Three general sessions (4 papers); Western Tight Gas (6 papers); Eastern Tight Gas (8 papers); Conventional/Speculative Resources (8 papers); and Gas to Liquids (6 papers). Individual reports are processed separately on the data bases.
Raman Gas Analyzer (RGA): Natural Gas Measurements.
Petrov, Dmitry V; Matrosov, Ivan I
2016-06-08
In the present work, an improved model of the Raman gas analyzer (RGA) of natural gas (NG) developed by us is described together with its operating principle. The sensitivity has been improved and the number of measurable gases has been expanded. Results of its approbation on a real NG sample are presented for different measurement times. A comparison of the data obtained with the results of chromatographic analysis demonstrates their good agreement. The time stability of the results obtained using this model is analyzed. It is experimentally established that the given RGA can reliably determine the content of all molecular NG components whose content exceeds 0.005% for 100 s; moreover, in this case the limiting sensitivity for some NG components is equal to 0.002%.
1998-01-01
About 16 000 Micro Strip Gas Chambers like this one will be used in the CMS tracking detector. They will measure the tracks of charged particles to a hundredth of a millimetre precision in the region near the collision point where the density of particles is very high. Each chamber is filled with a gas mixture of argon and dimethyl ether. Charged particles passing through ionise the gas, knocking out electrons which are collected on the aluminium strips visible under the microscope. Such detectors are being used in radiography. They give higher resolution imaging and reduce the required dose of radiation.
Babu, V
2014-01-01
Fundamentals of Gas Dynamics, Second Edition isa comprehensively updated new edition and now includes a chapter on the gas dynamics of steam. It covers the fundamental concepts and governing equations of different flows, and includes end of chapter exercises based on the practical applications. A number of useful tables on the thermodynamic properties of steam are also included.Fundamentals of Gas Dynamics, Second Edition begins with an introduction to compressible and incompressible flows before covering the fundamentals of one dimensional flows and normal shock wav
Gas Dynamics Equations: Computation
Chen, Gui-Qiang G
2012-01-01
Shock waves, vorticity waves, and entropy waves are fundamental discontinuity waves in nature and arise in supersonic or transonic gas flow, or from a very sudden release (explosion) of chemical, nuclear, electrical, radiation, or mechanical energy in a limited space. Tracking these discontinuities and their interactions, especially when and where new waves arise and interact in the motion of gases, is one of the main motivations for numerical computation for the gas dynamics equations. In this paper, we discuss some historic and recent developments, as well as mathematical challenges, in designing and formulating efficient numerical methods and algorithms to compute weak entropy solutions for the Euler equations for gas dynamics.
Gas solubilities widespread applications
Gerrard, William
1980-01-01
Gas Solubilities: Widespread Applications discusses several topics concerning the various applications of gas solubilities. The first chapter of the book reviews Henr's law, while the second chapter covers the effect of temperature on gas solubility. The third chapter discusses the various gases used by Horiuti, and the following chapters evaluate the data on sulfur dioxide, chlorine data, and solubility data for hydrogen sulfide. Chapter 7 concerns itself with solubility of radon, thoron, and actinon. Chapter 8 tackles the solubilities of diborane and the gaseous hydrides of groups IV, V, and
Rathakrishnan, Ethirajan
2014-01-01
This is an introductory level textbook which explains the elements of high temperature and high-speed gas dynamics. written in a clear and easy to follow style, the author covers all the latest developments in the field including basic thermodynamic principles, compressible flow regimes and waves propagation in one volume covers theoretical modeling of High Enthalpy Flows, with particular focus on problems in internal and external gas-dynamic flows, of interest in the fields of rockets propulsion and hypersonic aerodynamics High enthalpy gas dynamics is a compulsory course for aerospace engine
Tsai, Chi-Hung; Lai, Mei-Yi; Liu, Che-Wei; Huang, Shiang-Yin; Lin, Che-Yu; Yeh, Jeng-Sheng
In our digital art, we design a folding fan as an interactive magic device. You can use it to play with gas around the world of illusions. Although gas could not be seen in our real world, we still want to interact with it in our illusions by the element of bubble shadows. Opening and swinging the folding fan can blow the bubble shadows away; closing and swinging it can break bubbles. If the magic fan touches the shadow of gas, the bubble shadows will explode and release colorful particles to surround you. Those actions are controlled and located by our circuits with Arduino board.
Bechtel, William Theodore; Fitts, David Orus; DeLeonardo, Guy Wayne
2002-01-01
A diffusion flame nozzle gas tip is provided to convert a dual fuel nozzle to a gas only nozzle. The nozzle tip diverts compressor discharge air from the passage feeding the diffusion nozzle air swirl vanes to a region vacated by removal of the dual fuel components, so that the diverted compressor discharge air can flow to and through effusion holes in the end cap plate of the nozzle tip. In a preferred embodiment, the nozzle gas tip defines a cavity for receiving the compressor discharge air from a peripheral passage of the nozzle for flow through the effusion openings defined in the end cap plate.
US crude oil, natural gas, and natural gas liquids reserves
Energy Technology Data Exchange (ETDEWEB)
1990-10-05
This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1989, and production volumes for the year 1989 for the total United States and for selected states and state sub-divisions. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), its two major components (nonassociated and associated-dissolved gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, two components of natural gas liquids, lease condensate and natural gas plant liquids, have their reserves and production reported separately. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. 28 refs., 9 figs., 15 tabs.
46 CFR 30.10-29 - Gas free-TB/ALL.
2010-10-01
... 46 Shipping 1 2010-10-01 2010-10-01 false Gas free-TB/ALL. 30.10-29 Section 30.10-29 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-29 Gas free—TB/ALL. The term gas free means free from dangerous concentrations of flammable or toxic gases. ...
46 CFR 30.10-39 - Liquefied flammable gas-TB/ALL.
2010-10-01
... 46 Shipping 1 2010-10-01 2010-10-01 false Liquefied flammable gas-TB/ALL. 30.10-39 Section 30.10-39 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-39 Liquefied flammable gas—TB/ALL. The term liquefied flammable gas means any flammable gas...
Serakos, Demetrios
2015-01-01
This book defines and develops the generalized adjoint of an input-output system. It is the result of a theoretical development and examination of the generalized adjoint concept and the conditions under which systems analysis using adjoints is valid. Results developed in this book are useful aids for the analysis and modeling of physical systems, including the development of guidance and control algorithms and in developing simulations. The generalized adjoint system is defined and is patterned similarly to adjoints of bounded linear transformations. Next the elementary properties of the generalized adjoint system are derived. For a space of input-output systems, a generalized adjoint map from this space of systems to the space of generalized adjoints is defined. Then properties of the generalized adjoint map are derived. Afterward the author demonstrates that the inverse of an input-output system may be represented in terms of the generalized adjoint. The use of generalized adjoints to determine bounds for ...
Development of an LCV fuel gas combustor for an industrial gas turbine
Energy Technology Data Exchange (ETDEWEB)
Constant, D.R.; Bevan, D.M.; Cannon, M.F.; Kelsall, G.J. [British Coal Corporation, Stoke Orchard (United Kingdom). Coal Technology Development Division
1997-12-31
An important component of the Air Blown Gasification Cycle (ABGC) development is the gas turbine combustion system. It must burn low calorific value (LCV) coal derived fuel gas, at high turbine inlet temperatures with minimum pollutant emissions. A phase development programme has been completed burning LCV fuel gas (3.6-4.1 MJ/m{sup 3}) with low emissions, particularly NO{sub x} derived from fuel bound nitrogen. Performance tests were carried out on a generic tubo-annular, prototype combustor, at Mach numbers generally lower than those typical to engine applications, with encouraging results. Five design variants, operating at conditions selected to represent a particular medium sized industrial gas turbine each returned an improvement in combustor performance. A further five variants were investigated to establish which design characteristics and operating parameters most affected NO{sub x} emissions. 5 refs., 5 figs., 2 tabs.
Composite-fermionization of the mixture composed of Tonks gas and Fermi gas
Institute of Scientific and Technical Information of China (English)
Hao Ya-Jiang
2011-01-01
This paper investigates the ground-state properties of the mixture composed of the strongly interacting TonksGirardeau gas and spin polarized Fermi gas confined in one-dimensional harmonic traps, where the interaction between the Bose atoms and Fermi atoms is tunable. With a generalized Bose-Fermi transformation the mixture is mapped into a two-component Fermi gas. The homogeneous Fermi gas is exactly solvable by the Bethe-ansatz method and the ground state energy density can be obtained. Combining the ground-state energy function of the homogeneous system with local density approximation it obtains the ground-state density distributions of inhomogeneous mixture. It is shown that with the increase in boson-fermion interaction, the system exhibits composite-fermionization crossover.
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.
Department of Homeland Security — A hub is a physical transfer point for natural gas where several pipelines are connected. A market center is a hub where the operator offers services that facilitate...
Department of Homeland Security — Natural gas interstate and intrastate pipelines in the United States. Based on a variety of sources with varying scales and levels of accuracy and therefore accuracy...
... Chlorophyllin for Odor Control Digestive enzymes, such as lactase supplements, actually help digest carbohydrates and may allow ... have no effect on intestinal gas. The enzyme lactase, which aids with lactose digestion, is available in ...
2014-01-01
This book provides an overview on the particular development steps of gas insulated high-voltage switchgear, and is based on the information given with the editor's tutorial. The theory is kept low only as much as it is needed to understand gas insulated technology, with the main focus of the book being on delivering practical application knowledge. It discusses some introductory and advanced aspects in the meaning of applications. The start of the book presents the theory of Gas Insulated Technology, and outlines reliability, design, safety, grounding and bonding, and factors for choosing GIS. The third chapter presents the technology, covering the following in detail: manufacturing, specification, instrument transformers, Gas Insulated Bus, and the assembly process. Next, the book goes into control and monitoring, which covers local control cabinet, bay controller, control schemes, and digital communication. Testing is explained in the middle of the book before installation and energization. Importantly, ...
Davé, Romeel
2017-01-01
This edited volume presents the current state of gas accretion studies from both observational and theoretical perspectives, and charts our progress towards answering the fundamental yet elusive question of how galaxies get their gas. Understanding how galaxies form and evolve has been a central focus in astronomy for over a century. These studies have accelerated in the new millennium, driven by two key advances: the establishment of a firm concordance cosmological model that provides the backbone on which galaxies form and grow, and the recognition that galaxies grow not in isolation but within a “cosmic ecosystem” that includes the vast reservoir of gas filling intergalactic space. This latter aspect in which galaxies continually exchange matter with the intergalactic medium via inflows and outflows has been dubbed the “baryon cycle”. The topic of this book is directly related to the baryon cycle, in particular its least well constrained aspect, namely gas accretion. Accretion is a rare area of ast...
Energy Technology Data Exchange (ETDEWEB)
Lawlor, Shawn P.; Roberts, II, William Byron
2016-03-08
A gas turbine engine with a compressor rotor having compressor impulse blades that delivers gas at supersonic conditions to a stator. The stator includes a one or more aerodynamic ducts that each have a converging portion and a diverging portion for deceleration of the selected gas to subsonic conditions and to deliver a high pressure oxidant containing gas to flameholders. The flameholders may be provided as trapped vortex combustors, for combustion of a fuel to produce hot pressurized combustion gases. The hot pressurized combustion gases are choked before passing out of an aerodynamic duct to a turbine. Work is recovered in a turbine by expanding the combustion gases through impulse blades. By balancing the axial loading on compressor impulse blades and turbine impulse blades, asymmetrical thrust is minimized or avoided.
Logistics Group
2001-01-01
The contractor for the supply and distribution of pressurised gases has drawn our attention to the large number of gas bottles and banks being stored on the site for increasingly long periods. Users are reminded that the rental charges for gas bottles and banks are based on a progressive rate depending on their period of use. To assist CERN in its efforts to optimise its operations in this field, you are kindly requested : to return empty or unused containers to the official gas distribution points as soon as possible, to try to limit reserve stocks, bearing in mind that standardised gases can be delivered within 36 hours. This will result in a higher turnover rate and in increased safety and will improve the availability of the gases. For all further enquiries, please contact Gas.Store@cern.ch by e-mail or call 72265. Thank you for your co-operation.
2003-01-01
The contractor for the supply and distribution of pressurised gases has drawn our attention to the large number of gas bottles and banks being stored on the site for increasingly long periods. Users are reminded that the rental charges for gas bottles and banks are based on a progressive rate depending on their period of use. To assist CERN in its efforts to optimise its operations in this field, you are kindly requested: - to return empty or unused containers to the official gas distribution points as soon as possible - to try to limit reserve stocks, bearing in mind that standardised gases can be delivered within 36 hours. This will result in a higher turnover rate and in increased safety and will improve the availability of the gases. For all further enquiries, please contact "Gas store" by e-mail. Thank you for your co-operation. Logistics Group SPL Division
Logistics Group
2001-01-01
The contractor for the supply and distribution of pressurised gases has drawn our attention to the large number of gas bottles and banks being stored on the site for increasingly long periods. Users are reminded that the rental charges for gas bottles and banks are based on a progressive rate depending on their period of use. To assist CERN in its efforts to optimise its operations in this field, you are kindly requested : to return empty or unused containers to the official gas distribution points as soon as possible, to try to limit reserve stocks, bearing in mind that standardised gases can be delivered within 36 hours. This will result in a higher turnover rate and in increased safety and will improve the availability of the gases. For all further enquiries, please contact Gas.Store@cern.ch by e-mail or call 72265. Thank you for your co-operation.
Energy Technology Data Exchange (ETDEWEB)
Villar, M. V.; Gutierre-Rodrigo, V.; Martin, P. I.; Romero, F. J.; Barcala, J. M.
2013-07-01
The gas permeability of the Spanish FEBEX bentonite compacted at dry densities of between 1.4 and 1.8 g/cm{sup 3} with high water contents was measured for different confining, injection and back pressures. The results were compared with results obtained in previous investigations for lower degrees of saturation. It was checked that gas permeability was greatly affected by dry density, decreasing about three orders of magnitude when it increased from 1.5 to 1.8 g/cm{sup 3} for similar water content. The increase of water content caused also a decrease in gas permeability. It was found that both gas permeability and the relative gas permeability were mainly related to the accessible porosity. These relationships could be fitted to potential expressions with exponents between 3 and 4, as well as the relationship between intrinsic permeability and void ratio. For gas pressures below 1.2 MPa no effect of the injection or confining pressures on the value of permeability was detected. For a given confining pressure the permeability value decreased as the effective pressure increased, especially if the increase in effective pressure was due to a decrease in gas back pressure. It was checked that the Klinkenberg effect was not significant for this material in the range of pressures applied in the tests. The gas breakthrough pressure values in FEBEX saturated bentonite were determined for different dry densities. They increased clearly with dry density and were always higher than the swelling pressure of the bentonite. In high density samples gas flow tended to stop abruptly after breakthrough, whereas in lower density samples gas flow decreased gradually until a given pressure gradient was reached. The permeabilities computed after breakthrough (which usually did not stabilise) were inversely related to dry density. This would indicate that, even if the flow took place predominantly through preferential pathways that sometimes closed quickly after breakthrough and others
Explicit Integration of Friedmann's Equation with Nonlinear Equations of State
Chen, Shouxin; Yang, Yisong
2015-01-01
This paper is a continuation of our earlier study on the integrability of the Friedmann equations in the light of the Chebyshev theorem. Our main focus will be on a series of important, yet not previously touched, problems when the equation of state for the perfect-fluid universe is nonlinear. These include the generalized Chaplygin gas, two-term energy density, trinomial Friedmann, Born--Infeld, and two-fluid models. We show that some of these may be integrated using Chebyshev's result while other are out of reach by the theorem but may be integrated explicitly by other methods. With the explicit integration, we are able to understand exactly the roles of the physical parameters in various models play in the cosmological evolution. For example, in the Chaplygin gas universe, it is seen that, as far as there is a tiny presence of nonlinear matter, linear matter makes contribution to the dark matter, which becomes significant near the phantom divide line. The Friedmann equations also arise in areas of physics ...
Energy Technology Data Exchange (ETDEWEB)
NONE
2001-07-01
This preliminary report analyses the desirable evolutions of gas transport tariffing and examines some questions relative to the opening of competition on the French gas market. The report is made of two documents: a synthesis of the previous report with some recommendations about the tariffing of gas transport, about the modalities of network access to third parties, and about the dissociation between transport and trade book-keeping activities. The second document is the progress report about the opening of the French gas market. The first part presents the European problem of competition in the gas supply and its consequences on the opening and operation of the French gas market. The second part presents some partial syntheses about each topic of the mission letter of the Ministry of Economics, Finances and Industry: future evolution of network access tariffs, critical analysis of contractual documents for gas transport and delivery, examination of auxiliary services linked with the access to the network (modulation, balancing, conversion), consideration about the processing of network congestions and denied accesses, analysis of the metering dissociation between the integrated activities of gas operators. Some documents are attached in appendixes: the mission letter from July 9, 2001, the detailed analysis of the new temporary tariffs of GdF and CFM, the offer of methane terminals access to third parties, the compatibility of a nodal tariffing with the presence of three transport operators (GdF, CFM and GSO), the contract-type for GdF supply, and the contract-type for GdF connection. (J.S.)
On generalized extending modules
Institute of Scientific and Technical Information of China (English)
ZENG Qing-yi
2007-01-01
A module M is called generalized extending if for any submodule N of M, there is a direct summand K of M such that N≤K and K/N is singular. Any extending module and any singular module are generalized extending. Any homomorphic image of a generalized extending module is generalized extending. Any direct sum of a singular (uniform) module and a semi-simple module is generalized extending. A ring R is a right Co-H-ring ifand only ifall right R modules are generalized extending modules.
49 CFR 192.475 - Internal corrosion control: General.
2010-10-01
... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control: General. 192.475... Control § 192.475 Internal corrosion control: General. (a) Corrosive gas may not be transported by... taken to minimize internal corrosion. (b) Whenever any pipe is removed from a pipeline for any...
30 CFR 256.65 - Attorney General review.
2010-07-01
... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Attorney General review. 256.65 Section 256.65 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE LEASING OF SULPHUR OR OIL AND GAS IN THE OUTER CONTINENTAL SHELF Assignments, Transfers, and Extensions § 256.65 Attorney General review. Prior to the approval of an...
Research progress in studies on the coalbed gas geochemistry
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The current situation of geochemical studies on coalbed gas is reviewed in this paper. Generally, coalbed gas is compositionally dominated by methane with δ13C1 values ranging approximately from - 80‰ to - 10‰. However, few isotopic studies have been carried out on other components of coalbed gas except for hydrogen and carbon dioxide, whose δDCH4 values available for utilization vary from - 333‰ to - 117‰, and δ13CCO2 values from -29.4‰ to + 18.6‰. Two major types of coalbed gas, thermogenic gas and secondary biogenic gas, have been identified, and there are also some other classification criteria. Compared with conventional natural gases,coalbed gas has a wide distribution range of δ13C1 andδ13CCO2 values, especially possessing some extremely heavy values. Current problems that remain unsolved in the coalbed gas geochemistry include the variation mechanism, controlling factors and application of carbon and hydrogen isotopes of methane, the relation between the values of δ13C1 and Ro, the systematic classification scheme and criterion of genetic types, and the application of the coalbed gas geochemistry in evaluating target districts of the coalbed gas exploration.
Documentation of the Oil and Gas Supply Module (OGSM)
Energy Technology Data Exchange (ETDEWEB)
NONE
1998-01-01
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/Antrim shale and coalbeds. Crude oil and natural gas projections 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 profitability 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. Foreign gas trade may occur via either pipeline (Canada or Mexico), or via transport ships as liquefied natural gas (LNG). These import supply functions are critical elements of any market modeling effort.
Fracture development in shale and its relationship to gas accumulation
Directory of Open Access Journals (Sweden)
Wenlong Ding
2012-01-01
Full Text Available Shale with high quartz, feldspar and carbonate, will have low Poisson’s ratio, high Young’s modulus and high brittleness. As a result, the shale is conducive to produce natural and induced fractures under external forces. In general, there is a good correlation between fracture development in shale and the volume of brittle minerals present. Shale with high TOC or abnormally high pressure has well-developed fractures. Shale fracture development also shows a positive correlation with total gas accumulation and free gas volume, i.e., the better shale fractures are developed, the greater the gas accumulation and therefore the higher the gas production. Fractures provide migration conduits and accumulation spaces for natural gas and formation water, which are favorable for the volumetric increase of free natural gas. Wider fractures in shale result in gas loss. In North America, there is a high success ratio of shale gas exploration and high gas production from high-angle fracture zones in shale. Good natural gas shows or low yield producers in the Lower Paleozoic marine organic matter-rich rocks in the Sichuan Basin are closely related to the degree of fracture development in brittle shales.
Full Text Available ... are the limitations of General Ultrasound Imaging? What is General Ultrasound Imaging? Ultrasound is safe and painless, ... through the blood vessels. top of page How is the procedure performed? For most ultrasound exams, you ...
... IC Symptoms of IC General IC Symptoms General IC Symptoms Symptoms of interstitial cystitis (IC) differ from ... news and events. Please leave this field empty Interstitial Cystitis Association 7918 Jones Branch Drive, Suite 300 McLean, ...
Department of Transportation — Delphi general ledger contains the following data elements, but is not limited to the United States Standard General Ledger (USSGL) chart of accounts, stores actual,...
Gasotransmitters, poisons, and antimicrobials: it's a gas, gas, gas!
Tinajero-Trejo, Mariana; Jesse, Helen E; Poole, Robert K
2013-01-01
We review recent examples of the burgeoning literature on three gases that have major impacts in biology and microbiology. NO, CO and H2S are now co-classified as endogenous gasotransmitters with profound effects on mammalian physiology and, potentially, major implications in therapeutic applications. All are well known to be toxic yet, at tiny concentrations in human and cell biology, play key signalling and regulatory functions. All may also be endogenously generated in microbes. NO and H2S share the property of being biochemically detoxified, yet are beneficial in resisting the bactericidal properties of antibiotics. The mechanism underlying this protection is currently under debate. CO, in contrast, is not readily removed; mounting evidence shows that CO, and especially organic donor compounds that release the gas in biological environments, are themselves effective, novel antimicrobial agents.
Generalized convexity, generalized monotonicity recent results
Martinez-Legaz, Juan-Enrique; Volle, Michel
1998-01-01
A function is convex if its epigraph is convex. This geometrical structure has very strong implications in terms of continuity and differentiability. Separation theorems lead to optimality conditions and duality for convex problems. A function is quasiconvex if its lower level sets are convex. Here again, the geo metrical structure of the level sets implies some continuity and differentiability properties for quasiconvex functions. Optimality conditions and duality can be derived for optimization problems involving such functions as well. Over a period of about fifty years, quasiconvex and other generalized convex functions have been considered in a variety of fields including economies, man agement science, engineering, probability and applied sciences in accordance with the need of particular applications. During the last twenty-five years, an increase of research activities in this field has been witnessed. More recently generalized monotonicity of maps has been studied. It relates to generalized conve...
75 FR 54025 - Revision of LNG and LHG Waterfront Facility General Requirements
2010-09-03
...-27022] RIN 1625-AB13 Revision of LNG and LHG Waterfront Facility General Requirements AGENCY: Coast...) requirements for liquefied natural gas (LNG) and liquefied hazardous gas (LHG) facilities. The amendment... entitled ``Revision of LNG and LHG Waterfront Facility General Requirements'' (75 FR 29420) amending...
Keresztes, Zoltán; Kamenshchik, Alexander Yu
2012-01-01
A cosmological model of a flat Friedmann universe filled with a mixture of anti-Chaplygin gas and dust-like matter exhibits a future soft singularity, where the pressure of the anti-Chaplygin gas diverges (while its energy density vanishes). Despite infinite tidal forces the geodesics pass through the singularity. Due to the dust component, the Hubble parameter has a non-zero value at the encounter with the singularity, therefore the dust implies further expansion. With continued expansion however, the energy density and the pressure of the anti-Chaplygin gas would become ill-defined, hence from the point of view of the anti-Chaplygin gas only a contraction is allowed. Paradoxically, the universe in this cosmological model would have to expand and contract simultaneously. This obviosly could not happen. We solve the paradox by redefining the anti-Chaplygin gas in a distributional sense. Then a contraction could follow the expansion phase at the singularity at the price of a jump in the Hubble parameter. Altho...
Dewatering Techniques for Gas Recovery in Sichuan Gas Fields
Institute of Scientific and Technical Information of China (English)
Xu Kefang
1996-01-01
@@ Through several years' study for geology and development behavior of the gas fields, we realized that the water-bearing gas pools in Sichuan gas fields almost belong to enclosed weak elastic water drive gas pools, whether edge water gas pools or bottom water gas pools. According to the verification of drilling and production behavior data, in the periphery of Sichuan water-bearing gas pools, a screen is formed by gypsum salt, mudstone, or tight bed rock, with very low permeability, which blocks water percolation.
HD gas analysis with Gas Chromatography and Quadrupole Mass Spectrometer
Ohta, T; Didelez, J -P; Fujiwara, M; Fukuda, K; Kohri, H; Kunimatsu, T; Morisaki, C; Ono, S; Rouille, G; Tanaka, M; Ueda, K; Uraki, M; Utsuro, M; Wang, S Y; Yosoi, M
2011-01-01
A gas analyzer system has been developed to analyze Hydrogen-Deuteride (HD) gas for producing frozen-spin polarized HD targets, which are used for hadron photoproduction experiments at SPring-8. Small amounts of ortho-H$_{2}$ and para-D$_{2}$ gas mixtures ($\\sim$0.01%) in the purified HD gas are a key to realize a frozen-spin polarized target. In order to obtain reliable concentrations of these gas mixtures in the HD gas, we produced a new gas analyzer system combining two independent measurements with the gas chromatography and the QMS. The para-H$_{2}$, ortho-H$_{2}$, HD, and D$_{2}$ are separated using the retention time of the gas chromatography and the mass/charge. It is found that the new gas analyzer system can measure small concentrations of $\\sim$0.01% for the otho-H$_2$ and D$_2$ with good S/N ratios.
Ridgely, Charles T.
2010-01-01
Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…
Ridgely, Charles T.
2010-01-01
Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…
Generalized Poisson sigma models
Batalin, I; Batalin, Igor; Marnelius, Robert
2001-01-01
A general master action in terms of superfields is given which generates generalized Poisson sigma models by means of a natural ghost number prescription. The simplest representation is the sigma model considered by Cattaneo and Felder. For Dirac brackets considerably more general models are generated.
Generalized Fourier transforms classes
DEFF Research Database (Denmark)
Berntsen, Svend; Møller, Steen
2002-01-01
The Fourier class of integral transforms with kernels $B(\\omega r)$ has by definition inverse transforms with kernel $B(-\\omega r)$. The space of such transforms is explicitly constructed. A slightly more general class of generalized Fourier transforms are introduced. From the general theory...
Directory of Open Access Journals (Sweden)
Papiernik Bartosz
2015-04-01
Full Text Available Załęcze and Żuchlów are strongly depleted natural gas fields in aeolian sandstones of the Rotliegend, located in the central part of the Fore-Sudetic Monocline. A set of three static 3D models was generated to check the possibility of CO2 injection for Enhanced Gas Recovery (EGR and to check the safety of storage by means of geomechanical modeling: one regional model (ZZA and two local models – the first for Załęcze (ZA gas field and the second for Żuchlów (ZU gas field. The regional model is composed of 12 stratigraphic complexes (zones from the base of the Rotliegend to the ground surface. The local models comprise only the three lowermost complexes: fluvial deposits of the Rotliegend, aeolian sandstones of the Rotliegend (Reservoir I and basal Zechstein limestone, Ca1. The key elements of the modeling procedure include: Quality Control (QC of the data, interpretation of missing parameters necessary for static modeling and their integration within a geomodel. The processing workflow was elaborated to produce convergent regional and local models. The regional static model is a framework for a regional geomechanical model. The local models are the basis for dynamic simulations and local geomechanical modeling. The presented workflow could be used with some changes for geomodeling of many mature gas and oil fields.
Energy Technology Data Exchange (ETDEWEB)
NONE
2004-12-01
This document is a compilation of standard forms of concession agreements and of specifications for public gas distribution (general dispositions, granted network and works, connection to the granted network, gas quality, contracts and conditions of supply, gas prices, concession end and control, various dispositions, agreement between the town and the grantee, calculation of profit rate, gas retail prices, general conditions of supply). (J.S.)
Capability of the Gas Analysis and Testing Laboratory at the NASA Johnson Space Center
Broerman, Craig; Jimenez, Javier; Sweterlitsch, Jeff
2012-01-01
The Gas Analysis and Testing Laboratory is an integral part of the testing performed at the NASA Johnson Space Center. The Gas Analysis and Testing Laboratory is a high performance laboratory providing real time analytical instruments to support manned and unmanned testing. The lab utilizes precision gas chromatographs, gas analyzers and spectrophotometers to support the technology development programs within the NASA community. The Gas Analysis and Testing Laboratory works with a wide variety of customers and provides engineering support for user-specified applications in compressed gas, chemical analysis, general and research laboratory.
Energy Technology Data Exchange (ETDEWEB)
Kittel, J.; Fleury, E.; Gonzalez, S.; Ropital, F. [IFP Energies nouvelles, Rond point de l' echangeur de Solaize, 69360 Solaize (France); Vuillemin, B.; Oltra, R. [Institut Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 21078 Dijon Cedex (France)
2012-03-15
The aim of this paper is to review some of the parameters influencing the corrosivity of alkanolamine solvents used for natural gas purification or for CO{sub 2} capture. In the light of literature data and of new experimental results, the influences of temperature and of acid gas loading are discussed. These two parameters appear to have a strong impact on corrosion rates of carbon steel, with extrapolated corrosion rates of several tens of mm/year for the highest temperature and acid gas loading condition. It is then proposed to discuss about similarities and differences between natural gas processing and CO{sub 2} capture from flue gas. For both applications, alkanolamine processes are used. Still, differences can be found in operating parameters. The most significant gap concerns the lean amine sections. In acid gas treatment, the regeneration of the solvent is often performed down to zero loading. Under these conditions, an extremely low corrosivity of the lean solvent is expected. On the contrary, CO{sub 2} capture from flue gas requires only a partial stripping of the CO{sub 2} in the regeneration section, due to energy efficiency reasons. Then, the lean solvent still contains some acid gas, and subsequently a higher corrosivity. Finally, the general principles for material selection for the different parts of acid gas removal units are discussed, considering both cases of natural gas processing or CO{sub 2} capture. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Energy Technology Data Exchange (ETDEWEB)
Haglind, F. [Technical University of Denmark, Department of Mechanical Engineering, DK-2800 Kgs. Lyngby (Denmark)
2010-02-15
The part-load performance of gas and steam turbine combined cycles intended for naval use is of great importance, and it is influenced by the gas turbine configuration and load control strategy. This paper is aimed at quantifying the effects of variable geometry on the gas turbine part-load performance. Subsequently, in another paper, the effects of variable geometry on the part-load performance for combined cycles used for ship propulsion will be presented. Moreover, this paper is aimed at developing methodologies and deriving models for part-load simulations suitable for energy system analysis of various components within gas turbines. Two different gas turbine configurations are studied, a two-shaft aero-derivative configuration and a single-shaft industrial configuration. When both gas turbine configurations are running in part-load using fuel flow control, the results indicate better part-load performance for the two-shaft gas turbine. Reducing the load this way is accompanied by a much larger decrease in exhaust gas temperature for the single-shaft gas turbine than for the two-shaft configuration. As used here, the results suggest that variable geometry generally deteriorates the gas turbine part-load performance. (author)
Generalization Rough Set Theory
Institute of Scientific and Technical Information of China (English)
XIAO Di; ZHANG Jun-feng; HU Shou-song
2008-01-01
In order to avoid the discretization in the classical rough set theory, a generlization rough set theory is proposed.At first, the degree of general importance of an attribute and attribute subsets are presented.Then, depending on the degree of general importance of attribute, the space distance can be measured with weighted method.At last, a generalization rough set theory based on the general near neighborhood relation is proposed.The proposed theory partitions the universe into the tolerant modules, and forms lower approximation and upper approximation of the set under general near neighborhood relationship, which avoids the discretization in Pawlak's rough set theory.
Gratier, P; Schuster, K; Rosolowsky, E; Boquien, M; Calzetti, D; Combes, F; Kramer, C; Henkel, C; Herpin, F; Israel., F; Koribalski, B S; Mookerjea, B; Tabatabaei, F S; Röllig, M; van der Tak, F F S; van der Werf, P; Wiedner, M
2016-01-01
[Abridged] Do some environments favor efficient conversion of molecular gas into stars? To answer this, we need to be able to estimate the H2 mass. Traditionally, this is done using CO and a few assumptions but the Herschel observations in the FIR make it possible to estimate the molecular gas mass independently of CO. Previous attempts to derive gas masses from dust emission suffered from biases. Generally, dust surface densities, HI column densities, and CO intensities are used to derive a gas-to-dust ratio (GDR) and the local CO intensity to H2 column density ratio (XCO), sometimes allowing for an additional CO-dark gas component (Kdark). We tested earlier methods, revealing degeneracies among the parameters, and then used a Bayesian formalism to derive the most likely values for each of the parameters mentioned above as a function of position in the nearby low metallicity spiral galaxy M33. The data are from the IRAM 30m CO(2-1) line, high-resolution HI and Herschel dust continuum observations. Solving fo...
Gas turbine cleaning upgrade (compressor wash)
Energy Technology Data Exchange (ETDEWEB)
Asplund, P. [Gas Turbine Efficiency, Jarfalla (Sweden)
1998-12-31
The influence of gas turbine degradation on operating costs is high. Gas turbine cleaning is one of many actions taken for power recovery and is to consider as preventive maintenance. It is generally performed within the industrial field and occasionally within the aero sector. In order to meet the gas turbine development win high blade loads and ever-increasing temperatures, together with emission Aces and environmental regulations, more efficient and careful cleaning methods are needed. Following a survey about potentials for cost reduction in gas turbine operation a new man-hour and water saving cleaning method has been evaluated for a standard process. Compared with traditional cleaning methods, the new method is water,- cost,- weight and space saving due to a new washing technique. Traditional methods are based on using different nozzles for ON and OFF-line cleaning, which rise the demand for complicated systems. In the new method the same nozzle installation, same liquid flow and pressure is used for both ON and OFF-line cleaning. This gives a cost reduction of appr. 20.000 - 30.000 USD per gas turbine depending on installation and size. Evaluation of the new method shows significantly improved ON -line cleaning performance and thus OFF -line cleaning is required only during scheduled stops. (orig.) 10 refs.
Development of gas and gas condensate reservoirs
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-12-01
In the study of gas reservoir development, the first year topics are restricted on reservoir characterization. There are two types of reservoir characterization. One is the reservoir formation characterization and the other is the reservoir fluid characterization. For the reservoir formation characterization, calculation of conditional simulation was compared with that of unconditional simulation. The results of conditional simulation has higher confidence level than the unconditional simulation because conditional simulation considers the sample location as well as distance correlation. In the reservoir fluid characterization, phase behavior calculations revealed that the component grouping is more important than the increase of number of components. From the liquid volume fraction with pressure drop, the phase behavior of reservoir fluid can be estimated. The calculation results of fluid recombination, constant composition expansion, and constant volume depletion are matched very well with the experimental data. In swelling test of the reservoir fluid with lean gas, the accuracy of dew point pressure forecast depends on the component characterization. (author). 28 figs., 10 tabs.
Energy Technology Data Exchange (ETDEWEB)
Tetsuo, F.; Tokhikhide, N.
1984-04-19
A gas laser tube is described in which contamination of the laser gas mixture by the coolant is avoided, resulting in a longer service life of the mirrors. The holder contains two tubes, one inside the other. The laser gas mixture flows through the internal tube. An electrode is fastened to the holder. The coolant is pumped through the slot between the two tubes, for which a hole is cut into the holder. The external tube has a ring which serves to seal the cavity containing the coolant from the atmosphere. The internal tube has two rings, one to seal the laser gas mixture and the other to seal the coolant. A slot is located between these two rings, which leads to the atmosphere (the atmosphere layer). With this configuration, the degradation of the sealing properties of the internal ring caused by interaction with the atmospheric layer is not reflected in the purity of the laser gas mixture. Moreover, pollution of the mirrors caused by the penetration of the coolant into the cavity is eliminated.
The molecular gas mass of M 33
Gratier, P.; Braine, J.; Schuster, K.; Rosolowsky, E.; Boquien, M.; Calzetti, D.; Combes, F.; Kramer, C.; Henkel, C.; Herpin, F.; Israel, F.; Koribalski, B. S.; Mookerjea, B.; Tabatabaei, F. S.; Röllig, M.; van der Tak, F. F. S.; van der Werf, P.; Wiedner, M.
2017-03-01
Do some environments favor efficient conversion of molecular gas into stars? To answer this, we need to be able to estimate the H2 mass. Traditionally, this is done using CO observations and a few assumptions but the Herschel observations which cover the far-IR dust spectrum make it possible to estimate the molecular gas mass independently of CO and thus to investigate whether and how the CO traces H2. Previous attempts to derive gas masses from dust emission suffered from biases. Generally, dust surface densities, H i column densities, and CO intensities are used to derive a gas-to-dust ratio (GDR) and the local CO intensity to H2 column density ratio (XCO), sometimes allowing for an additional CO-dark gas component (Kdark). We tested earlier methods, revealing degeneracies among the parameters, and then used a sophisticated Bayesian formalism to derive the most likely values for each of the parameters mentioned above as a function of position in the nearby prototypical low metallicity (12 + log (O/H) 8.4) spiral galaxy M 33. The data are from the IRAM Large Program mapping in the CO(2-1) line along with high-resolution H i and Herschel dust continuum observations. Solving for GDR, XCO, and Kdark in macropixels 500 pc in size, each containing many individual measurements of the CO, H i, and dust emission, we find that (i) allowing for CO dark gas (Kdark) significantly improves fits; (ii) Kdark decreases with galactocentric distance; (iii) GDR is slightly higher than initially expected and increases with galactocentric distance; (iv) the total amount of dark gas closely follows the radially decreasing CO emission, as might be expected if the dark gas is H2 where CO is photodissociated. The total amount of H2, including dark gas, yields an average XCO of twice the galactic value of 2 × 1020 cm-2/ K km s-1, with about 55% of this traced directly through CO. The rather constant fraction of dark gas suggests that there is no large population of diffuse H2 clouds
THE VACUUM IN NONISENTROPIC GAS DYNAMICS
Institute of Scientific and Technical Information of China (English)
Geng Chen; Robin Young
2012-01-01
We investigate the vacuum in noniscntropic gas dynamics in one space variable,with the most general equation of states allowed by thermodynamics. Wc recall physical constraints on the equations of state and give explicit and easily checkable conditions under which vacuums occur in the solution of the Riemanu problem.We then present a class of models for which the Riemann problen admits unique global solutions without vacuums.
California Natural Gas Pipelines: A Brief Guide
Energy Technology Data Exchange (ETDEWEB)
Neuscamman, Stephanie [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Price, Don [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pezzola, Genny [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glascoe, Lee [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2013-01-22
The purpose of this document is to familiarize the reader with the general configuration and operation of the natural gas pipelines in California and to discuss potential LLNL contributions that would support the Partnership for the 21st Century collaboration. First, pipeline infrastructure will be reviewed. Then, recent pipeline events will be examined. Selected current pipeline industry research will be summarized. Finally, industry acronyms are listed for reference.
Prospects of and challenges to natural gas industry development in China
Directory of Open Access Journals (Sweden)
Jia Chengzao
2014-10-01
Full Text Available An unprecedented breakthrough has been made over the past decades in natural gas industry, which helps improve energy mix and promote the low-carbon economy in China. With such abundant hydrocarbon resources, China owns two intensive oil and gas producing blocks in the Ordos Basin and Xinjiang province and two other concentrated gas producing blocks in Sichuan and Western South Sea. In addition, arterial gas lines have been connected as a gas grid all over China and natural gas market has become more and more mature and expanded. Thus, a natural gas industry system has come into being. However, with natural gas unevenly scattering all across China, the remnant resources mainly are distributed in the stratigraphic strata, deep strata in superimposed basins or in mature exploration zones, foreland basin thrust belts, marine gas fields, and so on. In reality, the future gas exploration should focus on such domains as the weathered crust karst reservoirs or carbonate and stratigraphic traps, deep clastic gas layers, and unconventional oil and gas plays. Achievements have been made in marine shale gas exploration, CBM gas steady development, and other unconventional natural gas resources. From the perspective of exploration potential, more giant oil and gas fields will be possibly discovered in deep strata or deep sea water, and stratigraphic hydrocarbon reservoirs and tight oil and gas reservoirs will also be the exploration focus. With the increase of exploration depth and degree, the overall oil and gas exploration cost will be significantly rising in general. New discoveries or reserves increase in natural gas exploration will highly depend upon research theory and technology progress, and such development technologies as 3D seismic survey, horizontal drilling and fracturing treatment will be more highlighted. Through enhancing the cost in natural gas exploration and development and strengthening the research of core technologies, natural gas
... and beavers) has been infected with Giardia , the parasite lives in the intestines and is passed in feces (poop). Once outside ... parasite. People become infected when they swallow the parasite. It is not possible to become ... of intestinal symptoms, which include: Diarrhea Gas or flatulence Greasy ...
Baluarte. Instalaciones Generales.
Martín-Gómez, C. (César); Iriarte, J.M. (J.M.); Olaverri, J.A. (J.A.)
2004-01-01
En el presente texto se indican las características principales de las instalaciones del Palacio de Congresos y Auditorio de Navarra: protección contra incendios, aguas pluviales, saneamiento, energía eléctrica, climatización, suministro de gas natural e instalaciones de seguridad.
The characteristics of gas hydrates occurring in natural environment
Lu, H.; Moudrakovski, I.; Udachin, K.; Enright, G.; Ratcliffe, C.; Ripmeester, J.
2009-12-01
In the past few years, extensive analyses have been carried out for characterizing the natural gas hydrate samples from Cascadia, offshore Vancouver Island; Mallik, Mackenzie Delta; Mount Elbert, Alaska North Slope; Nankai Trough, offshore Japan; Japan Sea and offshore India. With the results obtained, it is possible to give a general picture of the characteristics of gas hydrates occurring in natural environment. Gas hydrate can occur in sediments of various types, from sands to clay, although it is preferentially enriched in sediments of certain types, for example coarse sands and fine volcanic ash. Most of the gas hydrates in sediments are invisible, occurring in the pores of the sediments, while some hydrates are visible, appearing as massive, nodular, planar, vein-like forms and occurring around the seafloor, in the fractures related to fault systems, or any other large spaces available in sediments. Although methane is the main component of most of the natural gas hydrates, C2 to C7 hydrocarbons have been recognized in hydrates, sometimes even in significant amounts. Shallow marine gas hydrates have been found generally to contain minor amounts of hydrogen sulfide. Gas hydrate samples with complex gas compositions have been found to have heterogeneous distributions in composition, which might reflect changes in the composition of the available gas in the surrounding environment. Depending on the gas compositions, the structure type of a natural gas hydrate can be structure I, II or H. For structure I methane hydrate, the large cages are almost fully occupied by methane molecules, while the small cages are only partly occupied. Methane hydrates occurring in different environments have been identified with almost the same crystallographic parameters.
Dolleman, Robin J.; Cartamil-Bueno, Santiago J.; van der Zant, Herre S. J.; Steeneken, Peter G.
2017-03-01
We show that graphene membranes that separate two gases at identical pressure are deflected by osmotic pressure. The osmotic pressure is a consequence of differences in gas permeation rates into a few-layer graphene enclosed cavity. The deflection of the membrane is detected by measuring the tension-induced resonance frequency with an interferometric technique. Using a calibration measurement of the relation between resonance frequency and pressure, the time dependent osmotic pressure on the graphene is extracted. The time dependent osmotic pressure for different combinations of gases shows large differences that can be accounted for by a model based on the different gas permeation rates. In this way, a graphene-membrane based gas osmometer with a responsivity of ˜60 kHz mbar-1 and nanoscale dimensions is demonstrated.
Energy Technology Data Exchange (ETDEWEB)
Sydzo, Y.
1984-03-27
It is reported that an improved design of a discharge tube for a gas laser is developed. A schematic of the discharge tube is given and its principle of operation is described in detail. In order to improve the flow of the gaseous active substance, it is proposed that tow additional incoming channels be used which are located between the primary incoming channels and the gas laser mirrors. The use of the additional incoming channels provides better circulation of the active medium in the regions near the laser mirrors. Thus, a more uniform heating of the region near the discharge tube is achieved due to the heat liberated from pumping discharge. It is noted that the proposed design serves to reduce the thermal deformation to the mirrors in the gas laser, and improves the laser efficiency.
Superdiffusive gas recovery from nanopores
Wu, Haiyi; He, Yadong; Qiao, Rui
2016-11-01
Understanding the recovery of gas from reservoirs featuring pervasive nanopores is essential for effective shale gas extraction. Classical theories cannot accurately predict such gas recovery and many experimental observations are not well understood. Here we report molecular simulations of the recovery of gas from single nanopores, explicitly taking into account molecular gas-wall interactions. We show that, in very narrow pores, the strong gas-wall interactions are essential in determining the gas recovery behavior both quantitatively and qualitatively. These interactions cause the total diffusion coefficients of the gas molecules in nanopores to be smaller than those predicted by kinetic theories, hence slowing down the rate of gas recovery. These interactions also lead to significant adsorption of gas molecules on the pore walls. Because of the desorption of these gas molecules during gas recovery, the gas recovery from the nanopore does not exhibit the usual diffusive scaling law (i.e., the accumulative recovery scales as R ˜t1 /2 ) but follows a superdiffusive scaling law R ˜tn (n >0.5 ), which is similar to that observed in some field experiments. For the system studied here, the superdiffusive gas recovery scaling law can be captured well by continuum models in which the gas adsorption and desorption from pore walls are taken into account using the Langmuir model.
Life-cycle analysis of shale gas and natural gas.
Energy Technology Data Exchange (ETDEWEB)
Clark, C.E.; Han, J.; Burnham, A.; Dunn, J.B.; Wang, M. (Energy Systems); ( EVS)
2012-01-27
The technologies and practices that have enabled the recent boom in shale gas production have also brought attention to the environmental impacts of its use. Using the current state of knowledge of the recovery, processing, and distribution of shale gas and conventional natural gas, we have estimated up-to-date, life-cycle greenhouse gas emissions. In addition, we have developed distribution functions for key parameters in each pathway to examine uncertainty and identify data gaps - such as methane emissions from shale gas well completions and conventional natural gas liquid unloadings - that need to be addressed further. Our base case results show that shale gas life-cycle emissions are 6% lower than those of conventional natural gas. However, the range in values for shale and conventional gas overlap, so there is a statistical uncertainty regarding whether shale gas emissions are indeed lower than conventional gas emissions. This life-cycle analysis provides insight into the critical stages in the natural gas industry where emissions occur and where opportunities exist to reduce the greenhouse gas footprint of natural gas.
Environmental risks associated with unconventional gas extraction: an Australian perspective
Mallants, Dirk; Bekele, Elise; Schmidt, Wolfgang; Miotlinski, Konrad; Gerke Gerke, Kirill
2015-04-01
Coal seam gas is naturally occurring methane gas (CH4) formed by the degradation of organic material in coal seam layers over geological times, typically over several millions of years. Unlike conventional gas resources, which occur as discrete accumulations in traps formed by folds and other structures in sedimentary layers, coal seam gas is generally trapped in low permeable rock by adsorption of the gas molecules within the rock formation and cannot migrate to a trap and form a conventional gas deposit. Extraction of coal seam gas requires producers to de pressurise the coal measures by abstracting large amounts of groundwater through pumping. For coal measures that have too low permeabilities for gas extraction to be economical, mechanical and chemical techniques are required to increase permeability and thus gas yield. One such technique is hydraulic fracturing (HF). Hydraulic fracturing increases the rate and total amount of gas extracted from coal seam gas reservoirs. The process of hydraulic fracturing involves injecting large volumes of hydraulic fracturing fluids under high pressure into the coal seam layers to open up (i.e. fracture) the gas-containing coal layers, thus facilitating extraction of methane gas through pumping. After a hydraulic fracturing operation has been completed in a coal seam gas well, the fracturing fluid pressure is lowered and a significant proportion of the injected fluid returns to the surface as "flowback" water via coal seam gas wells. Flowback water is fluid that returns to the surface after hydraulic fracturing has occurred but before the well is put into production; whereas produced water is fluid from the coal measure that is pumped to the surface after the well is in production. This paper summarises available literature data from Australian coal seam gas practices on i) spills from hydraulic fracturing-related fluids used during coal seam gas drilling and hydraulic fracturing operations, ii) leaks to soil and shallow
Schell, William J.
1979-01-01
A dry, fabric supported, polymeric gas separation membrane, such as cellulose acetate, is prepared by casting a solution of the polymer onto a shrinkable fabric preferably formed of synthetic polymers such as polyester or polyamide filaments before washing, stretching or calendering (so called griege goods). The supported membrane is then subjected to gelling, annealing, and drying by solvent exchange. During the processing steps, both the fabric support and the membrane shrink a preselected, controlled amount which prevents curling, wrinkling or cracking of the membrane in flat form or when spirally wound into a gas separation element.
Bowers, Michael T
1979-01-01
Gas Phase Ion Chemistry, Volume 1 covers papers on the advances of gas phase ion chemistry. The book discusses the advances in flow tubes and the measurement of ion-molecule rate coefficients and product distributions; the ion chemistry of the earth's atmosphere; and the classical ion-molecule collision theory. The text also describes statistical methods in reaction dynamics; the state selection by photoion-photoelectron coincidence; and the effects of temperature and pressure in the kinetics of ion-molecule reactions. The energy distribution in the unimolecular decomposition of ions, as well
Energy Technology Data Exchange (ETDEWEB)
Hoelter, H.; Gresch, H.; Igelbuescher, H.; Dewert, H.
1987-08-13
To avoid the problems of reheating in a wet process as well as the problems of higher gas supply in a dry process, the invention proposes to separate the raw gas in two component currents, one of which undergoes wet purification while the other is led through a dry purification process. The two component currents are mixed before entering the stack. The dry chemisorption masses added in substoichiometric doses are treated in a milk-of-lime processing stage, after which the reacted and non-reacted chemisorption masses are treated by wet purification and then by oxidation.
Energy Technology Data Exchange (ETDEWEB)
NONE
1972-06-01
Although most of the development work on fast breeder reactors has been devoted to the use of liquid metal cooling, interest has been expressed for a number of years in alternative breeder concepts using other coolants. One of a number of concepts in which interest has been retained is the Gas-Cooled Fast Reactor (GCFR). As presently envisioned, it would operate on the uranium-plutonium mixed oxide fuel cycle, similar to that used in the Liquid Metal Fast Breeder Reactor (LMFBR), and would use helium gas as the coolant.
Role of stranded gas in increasing global gas supplies
Attanasi, E.D.; Freeman, P.A.
2013-01-01
This report synthesizes the findings of three regional studies in order to evaluate, at the global scale, the contribution that stranded gas resources can make to global natural gas supplies. Stranded gas, as defined for this study, is natural gas in discovered conventional gas and oil fields that is currently not commercially producible for either physical or economic reasons. The regional studies evaluated the cost of bringing the large volumes of undeveloped gas in stranded gas fields to selected markets. In particular, stranded gas fields of selected Atlantic Basin countries, north Africa, Russia, and central Asia are screened to determine whether the volumes are sufficient to meet Europe’s increasing demand for gas imports. Stranded gas fields in Russia, central Asia, Southeast Asia, and Australia are also screened to estimate development, production, and transport costs and corresponding gas volumes that could be supplied to Asian markets in China, India, Japan, and South Korea. The data and cost analysis presented here suggest that for the European market and the markets examined in Asia, the development of stranded gas provides a way to meet projected gas import demands for the 2020-to-2040 period. Although this is a reconnaissance-type appraisal, it is based on volumes of gas that are associated with individual identified fields. Individual field data were carefully examined. Some fields were not evaluated because current technology was insufficient or it appeared the gas was likely to be held off the export market. Most of the evaluated stranded gas can be produced and delivered to markets at costs comparable to historical prices. Moreover, the associated volumes of gas are sufficient to provide an interim supply while additional technologies are developed to unlock gas diffused in shale and hydrates or while countries transition to making a greater use of renewable energy sources.
Energy Technology Data Exchange (ETDEWEB)
Chenoweth, D R
1983-06-01
An ideal-gas, quasi-steady, duct-flow model previously formulated for small scale gas-transfer problems is extended to real gases via the van der Waals equation of state as well as general virial expansions. The model is applicable for an arbitrary series of ducting components where each is described empirically by total pressure and total temperature change correlations. The adequacy of the van der Waals model for gas-transfer calculations is verified by comparisons with: (1) real gas PVT data; (2) the magnitudes of the controlling effects; and (3) approximate limiting case solutions with numerical results using more accurate real-gas modeling. 25 figures.
Gas phase dispersion in compost as a function of different water contents and air flow rates
Sharma, Prabhakar; Poulsen, Tjalfe G.
2009-07-01
Gas phase dispersion in a natural porous medium (yard waste compost) was investigated as a function of gas flow velocity and compost volumetric water content using oxygen and nitrogen as tracer gases. The compost was chosen because it has a very wide water content range and because it represents a wide range of porous media, including soils and biofilter media. Column breakthrough curves for oxygen and nitrogen were measured at relatively low pore gas velocities, corresponding to those observed in for instance soil vapor extraction systems or biofilters for air cleaning at biogas plants or composting facilities. Total gas mechanical dispersion-molecular diffusion coefficients were fitted from the breakthrough curves using a one-dimensional numerical solution to the advection-dispersion equation and used to determine gas dispersivities at different volumetric gas contents. The results showed that gas mechanical dispersion dominated over molecular diffusion with mechanical dispersion for all water contents and pore gas velocities investigated. Importance of mechanical dispersion increased with increasing pore gas velocity and compost water content. The results further showed that gas dispersivity was relatively constant at high values of compost gas-filled porosity but increased with decreasing gas-filled porosity at lower values of gas-filled porosity. Results finally showed that measurement uncertainty in gas dispersivity is generally highest at low values of pore gas velocity.
Energy Technology Data Exchange (ETDEWEB)
Bureau, D
2000-05-15
Among the various existing incentive mechanisms for the abatement of greenhouse gas emissions, like the pollution regulations and the financial help for energy mastery, this document analyzes the conditions of efficiency of the negotiated voluntary agreements and of the tradable emission quotas and their articulation with the fiscality. (J.S.)
Gas flow path for a gas turbine engine
Energy Technology Data Exchange (ETDEWEB)
Montgomery, Matthew D.; Charron, Richard C.; Snyder, Gary D.; Pankey, William W.; Mayer, Clinton A.; Hettinger, Benjamin G.
2017-03-14
A duct arrangement in a can annular gas turbine engine. The gas turbine engine has a gas delivery structure for delivering gases from a plurality of combustors to an annular chamber that extends circumferentially and is oriented concentric to a gas turbine engine longitudinal axis for delivering the gas flow to a first row of blades A gas flow path is formed by the duct arrangement between a respective combustor and the annular chamber for conveying gases from each combustor to the first row of turbine blades The duct arrangement includes at least one straight section having a centerline that is misaligned with a centerline of the combustor.
Unsupervised Learning and Generalization
DEFF Research Database (Denmark)
Hansen, Lars Kai; Larsen, Jan
1996-01-01
The concept of generalization is defined for a general class of unsupervised learning machines. The generalization error is a straightforward extension of the corresponding concept for supervised learning, and may be estimated empirically using a test set or by statistical means-in close analogy ...... with supervised learning. The empirical and analytical estimates are compared for principal component analysis and for K-means clustering based density estimation...
General surgery career resource.
Parsee, Ana M; Ross, Sharona B; Gantt, Nancy L; Kichler, Kandace; Hollands, Celeste
2013-11-01
General surgery residency training can lead to a rewarding career in general surgery and serve as the foundation for careers in several surgical subspecialties. It offers broad-based training with exposure to the cognitive and technical aspects of several surgical specialties and prepares graduating residents for a wide range of career paths. This career development resource discusses the training aspects of general surgery. Copyright © 2013 Elsevier Inc. All rights reserved.
Generalized Group Signature Scheme
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The concept of generalized group signature scheme will bepresent. Based on the generalized secret sharing scheme proposed by Lin and Ha rn, a non-interactive approach is designed for realizing such generalized group signature scheme. Using the new scheme, the authorized subsets of the group in w hich the group member can cooperate to produce the valid signature for any messa ge can be randomly specified
Generalized quasi variational inequalities
Energy Technology Data Exchange (ETDEWEB)
Noor, M.A. [King Saud Univ., Riyadh (Saudi Arabia)
1996-12-31
In this paper, we establish the equivalence between the generalized quasi variational inequalities and the generalized implicit Wiener-Hopf equations using essentially the projection technique. This equivalence is used to suggest and analyze a number of new iterative algorithms for solving generalized quasi variational inequalities and the related complementarity problems. The convergence criteria is also considered. The results proved in this paper represent a significant improvement and refinement of the previously known results.
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Geoinformation Generalization by Aggregation
Directory of Open Access Journals (Sweden)
Tomislav Jogun
2016-12-01
Full Text Available Geoinformation generalization can be divided into model generalization and cartographic generalization. Model generalization is the supervised reduction of data in a model, while cartographic generalization is the reduction of the complexity of map content adapted to the map scale, and/or use by various generalization operators (procedures. The topic of this paper is the aggregation of geoinformation. Generally, aggregation is the joining of nearby, congenial objects, when the distance between them is smaller than the minimum sizes. Most researchers in geoinformation generalization have focused on line features. However, the appearance of web-maps with point features and choropleth maps has led to the development of concepts and algorithms for the generalization of point and polygonal features. This paper considers some previous theoretical premises and actual examples of aggregation for point, line and polygonal features. The algorithms for aggregation implemented in commercial and free GIS software were tested. In the conclusion, unresolved challenges that occur in dynamic cartographic visualizations and cases of unusual geometrical features are highlighted.
Generalized Fibonacci zone plates
Ke, Jie; Zhu, Jianqiang
2015-01-01
We propose a family of zone plates which are produced by the generalized Fibonacci sequences and their axial focusing properties are analyzed in detail. Compared with traditional Fresnel zone plates, the generalized Fibonacci zone plates present two axial foci with equal intensity. Besides, we propose an approach to adjust the axial locations of the two foci by means of different optical path difference, and further give the deterministic ratio of the two focal distances which attributes to their own generalized Fibonacci sequences. The generalized Fibonacci zone plates may allow for new applications in micro and nanophotonics.
Life-cycle greenhouse gas emissions of shale gas, natural gas, coal, and petroleum.
Burnham, Andrew; Han, Jeongwoo; Clark, Corrie E; Wang, Michael; Dunn, Jennifer B; Palou-Rivera, Ignasi
2012-01-17
The technologies and practices that have enabled the recent boom in shale gas production have also brought attention to the environmental impacts of its use. It has been debated whether the fugitive methane emissions during natural gas production and transmission outweigh the lower carbon dioxide emissions during combustion when compared to coal and petroleum. Using the current state of knowledge of methane emissions from shale gas, conventional natural gas, coal, and petroleum, we estimated up-to-date life-cycle greenhouse gas emissions. In addition, we developed distribution functions for key parameters in each pathway to examine uncertainty and identify data gaps such as methane emissions from shale gas well completions and conventional natural gas liquid unloadings that need to be further addressed. Our base case results show that shale gas life-cycle emissions are 6% lower than conventional natural gas, 23% lower than gasoline, and 33% lower than coal. However, the range in values for shale and conventional gas overlap, so there is a statistical uncertainty whether shale gas emissions are indeed lower than conventional gas. Moreover, this life-cycle analysis, among other work in this area, provides insight on critical stages that the natural gas industry and government agencies can work together on to reduce the greenhouse gas footprint of natural gas.
DEFF Research Database (Denmark)
Carlsen, Lars; Egsgaard, Helge
1982-01-01
The unimolecular gas-phase thermolyses of 1,2,3-oxadithiolan 2-oxide and thiiran 1-oxide have been studied by the flash vacuum thermolysis–field ionization mass spectrometry (f.v.t.–f.i.m.s.) technique in the temperature range from 1 043 to 1 404 K. The reactions are rationalized in terms...