2,972 research outputs found
Effects of Thermal Fluctuations on Non-minimal Regular Magnetic Black Hole
We analyze the effects of thermal fluctuations on a regular black hole (RBH)
of non-minimal Einstein-Yang-Mill theory with gauge field of magnetic Wu-Yang
type and a cosmological constant. We consider the logarithmic corrected entropy
in order to analyze the thermal fluctuations corresponding to non-minimal RBH
thermodynamics. In this scenario, we develop various important thermodynamical
quantities such as entropy, pressure, specific heats, Gibb's free energy and
Helmothz free energy. We investigate first law of thermodynamics in the
presence of logarithmic corrected entropy and non-minimal RBH. We also discuss
the stability of this RBH using various frameworks such as factor
(comprises of ratio of heat capacities), phase transition, grand canonical
ensemble and canonical ensemble. It is observed that the non-minimal RBH
becomes more globally and locally stable if we increase the value of
cosmological constant.Comment: 20 pages, 5 figure
The Michaelis-Menten-Stueckelberg Theorem
We study chemical reactions with complex mechanisms under two assumptions:
(i) intermediates are present in small amounts (this is the quasi-steady-state
hypothesis or QSS) and (ii) they are in equilibrium relations with substrates
(this is the quasiequilibrium hypothesis or QE). Under these assumptions, we
prove the generalized mass action law together with the basic relations between
kinetic factors, which are sufficient for the positivity of the entropy
production but hold even without microreversibility, when the detailed balance
is not applicable. Even though QE and QSS produce useful approximations by
themselves, only the combination of these assumptions can render the
possibility beyond the "rarefied gas" limit or the "molecular chaos"
hypotheses. We do not use any a priori form of the kinetic law for the chemical
reactions and describe their equilibria by thermodynamic relations. The
transformations of the intermediate compounds can be described by the Markov
kinetics because of their low density ({\em low density of elementary events}).
This combination of assumptions was introduced by Michaelis and Menten in 1913.
In 1952, Stueckelberg used the same assumptions for the gas kinetics and
produced the remarkable semi-detailed balance relations between collision rates
in the Boltzmann equation that are weaker than the detailed balance conditions
but are still sufficient for the Boltzmann -theorem to be valid. Our results
are obtained within the Michaelis-Menten-Stueckelbeg conceptual framework.Comment: 54 pages, the final version; correction of a misprint in Attachment
Tidal Forces in Kiselev Black Hole
The aim of this paper is to examine the tidal forces occurred in Kiselev
black hole surrounded by radiation and dust fluids. It is noted that radial and
angular component of tidal force change the sign between event and Cauchy
horizons. We solve the geodesic deviation equation for radially free falling
bodies toward Kiselev black holes. We explain the geodesic deviation vector
graphically and point out the location of event and Cauchy horizons in it for
specific values of radiation and dust parameter.Comment: 20 pages, 10 figure
Accretion onto Some Well-Known Regular Black Holes
In this work, we discuss the accretion onto static spherical symmetric
regular black holes for specific choices of equation of state parameter. The
underlying regular black holes are charged regular black hole using Fermi-Dirac
Distribution, logistic distribution, nonlinear electrodynamics, respectively
and Kehagias-Sftesos asymptotically flat regular black hole. We obtain the
critical radius, critical speed and squared sound speed during the accretion
process near the regular black holes. We also study the behavior of radial
velocity, energy density and rate of change of mass for each regular black
holes.Comment: 25 pages, 7 figures, Accepted for publication in Eur. Phys. J.
Accreting Fluids onto Regular Black Holes Via Hamiltonian Approach
We investigate the accretion of test fluids onto regular black holes such as
Kehagias-Sfetsos black hole and a regular black hole with Dagum Distribution
Function. We analyze the accretion process when different test fluids are
falling onto these regular black holes. The accreting fluid is being classified
through equation of state according to features of regular black holes. The
behavior of fluid flow and the existence of sonic points is being checked for
these regular black holes. It is noted that three velocity depends on critical
points and equation of state parameter on phase space.Comment: 25 pages; 10 Figure
A New Model of Quintessence Compact Stars in Rastall Theory of Gravity
In the present work, we study a new model of anisotropic compact stars in the
regime of Rastall theory. To solve the Rastall field equations we have used the
Karori and Barua (KB) ansatz along with the quintessence dark energy
characterized by a parameter with . We
present a comparative study to demonstrate the physical acceptance of our
proposed model. We compare the numerical values of physical parameters obtained
from our model with those of general relativity () model given by Bhar
\cite{1} and observe that our model is more compatible (for some chosen values
of Rastall dimensionless parameter ) with observational
data than model. For this analysis we have consider four different compact
stars, , , and
with radii , , and , respectively. In this
investigation we also present some physical aspects of the proposed model
necessary to check the validity of the model and inferred that our model is
acceptable physically and geometrically.Comment: 20 pages, 16 figures, 8 tables, Accepted for Publication in Eur.
Physical Journal
Thermodynamics of Black holes With Higher Order Corrected Entropy
For analyzing the thermodynamical behavior of two well-known black holes such
as RN-AdS black hole with global monopole and black hole, we consider
the higher order logarithmic corrected entropy. We develop various
thermodynamical properties such as, entropy, specific heats, pressure, Gibb's
and Helmhotz free energies for both black holes in the presence of corrected
entropy. The versatile study on the stability of black holes is being made by
using various frameworks such as the ratio of heat capacities (), grand
canonical and canonical ensembles, and phase transition in view of higher order
logarithmic corrected entropy. It is observed that both black holes exhibit
more stability (locally as well as globally) for growing values of cosmological
constant and higher order correction terms.Comment: 23 pages, 10 figures, accepted for publication by Canadian Journal of
Physics. arXiv admin note: text overlap with arXiv:1701.08650 by other
author
Influence of temperature on the performance of a full-scale activated sludge process operated at varying solids retention times whilst treating municipal sewage
In this study, the solid retention time (SRT) was varied with the ambient temperature for a full-scale municipal activated sludge plant with capacity of 200,000 PE (Population Equivalent) located in a humid sub-tropical environment. The effects of ambient temperature on treatment performance were investigated. Off-line samples were collected and analyzed from the treatment plant. The actual temperature variation during the study period was divided into three overlapping ranges and the SRT was adjusted accordingly with temperature in order to achieve the desired effluent quality. The plant’s observed effluent quality and thereby its overall removal efficiency was evaluated in terms of measuring standard biochemical parameters. The results indicate that significant improvement in effluent quality can be obtained by applying the variable SRT (5–7 days) dependent on temperature variation
Monetary policy restriction and dividend behavior of Pakistani firms: an empirical analysis
Studies upon impact of macro variables on firm’s dividend policy are very limited and specifically rare in Pakistan perspective. Main purpose of this research paper is to observe impact of restricted monetary policy on dividend behavior of Pakistani firms. During restricted monetary policy, cost of external funds increases and firms prefer to utilize internal funds leading to reduction in dividend payout. Behaviour of 100 listed firms, selected purposefully, has been observed for the period from 2001 to 2009 by using Lintner’ modified model.. During the research period of nine years, monetary policy has been gone through both loose and tight phases. Proposed model is dynamic one as lagged dependent variable has been used as explanatory variable. Due to certain limitations with selection of monetary policy instrument, overall stance of State Bank of Pakistan (SBP) in its annual reports has been used as a dummy variable in the model. Results of all the three estimations reveal almost same results. First lagged dividend has been proved to be most deterministic factor of dividend policy followed by current earnings. Monetary policy and lagged dividends interactive variables provide mixed results. First interactive variable has negative coefficients in all three, fixed effect, random effects and GMM, models but with insignificant p values. Second monetary policy interactive variable has positive coefficients with significant values in random effects and GMM model. Firms seem to follow relatively stable dividend policies with lower adjustment factor. As model is dynamic, GMM estimation is preferred. Monetary policy has not been observed as significant determinant of dividend policy of Pakistani firms.Dividend payment, Monetary Policy
- …