Showing papers in "Entropy in 2006"

Second Law Analysis in Convective Heat and Mass Transfer

Abstract: This paper reports the numerical determination of the entropy generation due to heat transfer, mass transfer and fluid friction in steady state for laminar double diffusive convection, in an inclined enclosure with heat and mass diffusive walls, by solving numerically the mass, momentum, species conservation and energy balance equations, using a Control Volume Finite-Element Method. The influences of the inclination angle, the thermal Grashof number and the buoyancy ratio on total entropy generation were investigated. The irreversibilities localization due to heat transfer, mass transfer and fluid friction is discussed for three inclination angles at a fixed thermal Grashof number.

Entropy generation in pressure gradient assisted couette flow with different thermal boundary conditions

Abstract: The present paper is concerned with an analytical study of entropy generation in viscous, incompressible Couette flow between a stationary plate and a moving plate. The flow induced by the moving plate is assisted by a constant pressure gradient along the flow direction. Four different combinations of thermal boundary conditions are investigated: (a) plates at different temperatures, (b) stationary plate at a fixed temperature and moving plate subjected to a constant heat flux, (c) stationary plate at a fixed temperature and convection at the moving plate, and (d) convection at both plates. Besides the velocity and temperature profiles, dimensionless results are presented for the entropy generated due to heat transfer, the entropy generated due to viscous dissipation, and the total entropy generation. These results illustrate the effect of pressure gradient, temperature asymmetry, heat flux, convection Biot numbers, and ambient temperatures. For certain combinations of thermal variables, the total entropy generated is minimized.

Thermodynamic Analysis of Gravity-driven Liquid Film along an Inclined Heated Plate with Hydromagnetic and Viscous Dissipation Effects

Abstract: The purpose of this work is to investigate the entropy generation in a laminar,gravity-driven conducting liquid film with fully developed velocity flowing along an inclineheated plate in the presence of a transverse magnetic field. The upper surface of the liquidfilm is considered free and adiabatic. The effect of heat generation by viscous dissipation isincluded in the analysis. The influence of the applied magnetic field and the viscousdissipation on velocity, temperature and entropy generation is examined.

Deformed Density Matrix and Quantum Entropy of the Black Hole

Abstract: In the present work the approach - density matrix deformation - earlier developed by the author to study a quantum theory of the Early Universe (Planck's scales) is applied to study a quantum theory of black holes. On this basis the author investigates the information paradox problem, entropy of the black hole remainders after evaporation, and consistency with the holographic principle. The possibility for application of the proposed approach to the calculation of quantum entropy of a black hole is considered.

Entropy and Effective Support Size

Abstract: Notion of Effective size of support (Ess) of a random variable is introduced. A smallset of natural requirements that a measure of Ess should satisfy is presented. The measure withprescribed properties is in a direct (exp-) relationship to the family of R nyi’s α-entropies which eincludes also Shannon’s entropy H. Considerations of choice of the value of α imply that exp(H)appears to be the most appropriate measure of Ess.Entropy and Ess can be viewed thanks to their log / exp relationship as two aspects of the samething. In Probability and Statistics the Ess aspect could appear more basic than the entropic one.

Utility Function from Maximum Entropy Principle

Abstract: Amir H. DaroonehSufi Institute, P.O.Box 45195-1547, Zanjan, IranandDepartment of Physics, Zanjan University, P.O.Box 45196-313, Zanjan, Iran.E-mail: darooneh@mail.znu.ac.irReceived: 4 December 2005 / Accepted: 30 January 2006 / Published: 31 January 2006Abstract: Recently we used the maximum entropy principle for finding the price density in amulti agent insurance market. The result is similar to what the Buhlmann had obtained by max-imizing the utility function. Here we begin with the price density that is derived by applying themaximum entropy principle to a conservative economic system (exchange market), then reversethe Buhlmann calculation to find the utility function and the risk aversion of agents with respectto this density.Keywords: Utility Function, Price Density, Maximum Entropy Principle, Risk Aversion.PACS codes:89.65.Gh, 05.20.-y.

Calculations of System Aging through the Stochastic Entropy

Abstract: The present research discusses four ‘physical’ models of system and calculates the reliability function during system’s aging and maturity on the basis of the system structure. Keywords: System aging, Boltzmann-like entropy, reliability function, Weibull distribution, Gompertz distribution. 1. Introduction Attempts to develop a fundamental quantitative theory of aging, mortality, and lifespan have deep historical roots. Studies upon aging started with the earliest statistical studies on human mortality and later embraced both biological and artificial systems. Endeavors to classify theories of aging have led to the two major classifications. We find ‘wear and tear theories’ that sustain aging is the effect of the sum effect of many kinds of environmental assaults (e.g. radiation, metal ions) and of internal deterioration (e.g. mechanical attrition, spin-off accumulation) [1]. At the other side ‘programmed aging theories’ hold aging is due to something inside an organism's control mechanisms that forces elderliness and deterioration [2], [3]. The latter school is particular popular in the biological realm, while the former is formally sustained by the

Symmetry Studies and Decompositions of Entropy

Abstract: This paper describes a group-theoretic method for decomposing the entropy of a finite ensemble when symmetry considerations are of interest. The cases in which the elements in the ensemble are indexed by {1,2,...,n} and by the permutations of a finite set are considered in detail and interpreted as particular cases of ensembles with elements indexed by a set subject to the actions of a finite group. Decompositions for the entropy in binary ensembles and in ensembles indexed by short DNA words are discussed. Graphical descriptions of the decompositions of the entropy in geological samples are illustrated. The decompositions derived in the present cases follow from a systematic data analytic tool to study entropy data in the presence of symmetry considerations.

Unsteady Volumetric Entropy Generation Rate in Laminar Boundary Layers

Abstract: The prediction of the entropy generation rate in laminar shear layers is treated as steady, even in the presence of high levels of free stream turbulence. Here we highlight the deficiencies of this approach by quantifying the magnitude of entropy generation rate fluctuations in the laminar boundary layer subjected to free stream turbulence. We find fluctuation levels in excess of 100% in the near wall region, thereby indicating the need to account for the unsteadiness in laminar boundary layers subjected to free stream turbulence.

Structuring Information and Entropy: Catalyst as Information Carrier

Abstract: Many authors tried to exploit the similarities between expressions of the statistical thermodynamics for the entropy and those of Shannon's information theory. In a new approach, we highlight the role of information involved in chemical systems, in particular in the interaction between catalysts and reactants, what we call structuring information. By means of examples, we present some applications of this concept to the biosphere, by visiting a very vast domain going from the appearance of life on earth to its present evolution.

On the Propagation of Blast Wave in Earth′s Atmosphere: Adiabatic and Isothermal Flow

Abstract: Adiabatic and isothermal propagations of spherical blast wave produced due to a nuclear explosion have been studied using the Energy hypothesis of Thomas, in the nonuniform atmosphere of the earth The explosion is considered at different heights Entropy production is also calculated along with the strength and velocity of the shock In both the cases; for adiabatic and isothermal flows, it has been found that shock strength and shock velocity are larger at larger heights of explosion, in comparison to smaller heights of explosion Isothermal propagation leads to a smaller value of shock strength and shock velocity in comparison to the adiabatic propagation For the adiabatic case, the production of entropy is higher at higher heights of explosion, which goes on decreasing as the shock moves away from the point of explosion However for the isothermal shock, the calculation of entropy production shows negative values With negative values for the isothermal case, the production of entropy is smaller at higher heights of explosion, which goes on increasing as the shock moves away from the point of explosion Directional study of the shock motion and entropy production show that in both the cases of adiabatic and isothermal flow, shock strength and shock velocity are larger in upward motion of the shock, in comparison to the downward motion of the shock For adiabatic flow, entropy production is larger in upward motion of the shock; whereas, with negative values, entropy production is smaller in upward motion of the isothermal shock For the adiabatic case, the profiles of shock strength, shock velocity and entropy production are smooth and have the largest value in vertically upward direction and have the lowest value in vertically downward direction, forming the oval shape For the isothermal case, the profiles of shock strength and shock velocity show similar trend as that for adiabatic case but the profile of entropy production shows opposite trend The profiles maintain their shape as the shock moves away Comparison with observed values of shock velocity shows that isothermal case produces better results in comparison to the adiabatic case

Entropy and Energy in Quantum Measurement

Abstract: On the basis of the classical axioms of non relativistic quantum mechanics, we develop a model for the interplay between energy and entropy in the process of quantum measurement and shed light on the scope of some of the axioms with regard to the measurement problem.

Inference with the Median of a Prior

Abstract: We consider the problem of inference on one of the two parameters of a probability distribution when we have some prior information on a nuisance parameter. When a prior probability distribution on this nuisance parameter is given, the marginal distribution is the classical tool to account for it. If the prior distribution is not given, but we have partial knowledge such as a fixed number of moments, we can use the maximum entropy principle to assign a prior law and thus go back to the previous case. In this work, we consider the case where we only know the median of the prior and propose a new tool for this case. This new inference tool looks like a marginal distribution. It is obtained by first remarking that the marginal distribution can be considered as the mean value of the original distribution with respect to the prior probability law of the nuisance parameter, and then, by using the median in place of the mean.

Open Access Publishing Policy and Efficient Editorial Procedure

Abstract: With the development of Internet, human societies have evolved rapidly with the emerging information society. The way of scientific communication has been changing dramatically. After a few years, the Online Journal publishing has been completely accepted by all scientific communities. The traditional business model of subscription based journal publishing is being challenged by the alternative Open Access publishing model [1-3]. However, financia lly sustainable Open Access publishing is still a goal difficult to reach. Dr. Shu-Kun Lin has been identified among the pioneers of Open Access in Natural Sciences, and has been managing online open access journals for about 10 years [4]. Dr. Derek McPhee and Dr. Francis Muguet have tried to help Dr. Shu-Kun Lin in order to make Open Access publishing a sustainable alternative which can be tentatively assessed,

Time in Quantum Measurement

Abstract: Based on a model of quantum measurement we derive an estimate for the external measurement-time. Some interesting consequences will be analyzed.

Generalized Ideal Gas Equations for Structureful Universe

Abstract: 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.