Next Issue
Previous Issue

E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Table of Contents

Entropy, Volume 9, Issue 3 (September 2007), Pages 100-151

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-6
Export citation of selected articles as:

Research

Jump to: Other

Open AccessArticle Thermodynamics of Horizons from a Dual Quantum System
Entropy 2007, 9(3), 100-107; doi:10.3390/e9030100
Received: 10 July 2007 / Accepted: 13 August 2007 / Published: 20 August 2007
Cited by 3 | PDF Full-text (162 KB)
Abstract
It was shown recently that, in the case of Schwarschild black hole, one can obtainthe correct thermodynamic relations by studying a model quantum system and using a partic-ular duality transformation. We study this approach further for the case a general sphericallysymmetric horizon. [...] Read more.
It was shown recently that, in the case of Schwarschild black hole, one can obtainthe correct thermodynamic relations by studying a model quantum system and using a partic-ular duality transformation. We study this approach further for the case a general sphericallysymmetric horizon. We show that the idea works for a general case only if we define the en-tropy S as a congruence (“observer”) dependent quantity and the energy E as the integral overthe source of the gravitational acceleration for the congruence. In fact, in this case, one recov-ers the relation S = E/2T between entropy, energy and temperature previously proposed byone of us in gr-qc/0308070. This approach also enables us to calculate the quantum correc-tions of the Bekenstein-Hawking entropy formula for all spherically symmetric horizons. Full article
Open AccessArticle A Model of Time
Entropy 2007, 9(3), 108-112; doi:10.3390/e9030108
Received: 19 July 2007 / Accepted: 5 September 2007 / Published: 7 September 2007
Cited by 1 | PDF Full-text (151 KB) | HTML Full-text | XML Full-text
Abstract Based on a mathematical model of quantum measurement we derive some properties of intuitive time. Full article
Open AccessArticle On Darcy-Brinkman Equation: Viscous Flow Between Two Parallel Plates Packed with Regular Square Arrays of Cylinders
Entropy 2007, 9(3), 118-131; doi:10.3390/e9030118
Received: 12 December 2006 / Accepted: 5 September 2007 / Published: 11 September 2007
Cited by 14 | PDF Full-text (1339 KB) | HTML Full-text | XML Full-text
Abstract
Effects of the bounding solid walls are examined numerically for slow flow overregular, square arrays of circular cylinders between two parallel plates. A local magnitudeof the rate of entropy generation is used effectively to determine the flow region affected bythe presence of [...] Read more.
Effects of the bounding solid walls are examined numerically for slow flow overregular, square arrays of circular cylinders between two parallel plates. A local magnitudeof the rate of entropy generation is used effectively to determine the flow region affected bythe presence of the solid boundary. Computed axial pressure gradients are compared to thecorresponding solution based on the Darcy-Brinkman equation for porous media in whichthe effective viscosity appears as an additional property to be determined from the flowcharacteristics. Results indicate that, between two limits of the Darcian porous medium andthe viscous flow, the magnitude of μ (the ratio of the effective viscosity to the fluid ˆviscosity) needs to be close to unity in order to satisfy the non-slip boundary conditions atthe bounding walls. Although the study deals with a specific geometric pattern of the porousstructure, it suggests a restriction on the validity of the Darcy-Brinkman equation to modelhigh porosity porous media. The non-slip condition at the bounding solid walls may beaccounted for by introducing a thin porous layer with μ = 1 near the solid walls. ˆ Full article
Open AccessArticle Distillation of a Complex Mixture. Part II: Performance Analysis of a Distillation Column Using Exergy
Entropy 2007, 9(3), 137-151; doi:10.3390/e9030137
Received: 7 December 2006 / Accepted: 13 September 2007 / Published: 25 September 2007
Cited by 5 | PDF Full-text (258 KB) | HTML Full-text | XML Full-text
Abstract
To analyze the performance of the separation process, we have introduced thethermodynamic concept of exergy through the exergetic efficiency of the column. Thesimulation results show that the exergetic output is relatively low and that the producedirreversibility fluxes are distributed throughout the whole [...] Read more.
To analyze the performance of the separation process, we have introduced thethermodynamic concept of exergy through the exergetic efficiency of the column. Thesimulation results show that the exergetic output is relatively low and that the producedirreversibility fluxes are distributed throughout the whole column in a non-uniform manner.They are particularly significant in the condenser, boiler and tray feed. The influence of thevarious operating parameters (temperature, concentration and irreversibility in both sectionsof the column) is also established. To emphasize the results, the relation in equation 17, ispresented graphically to evaluate the cumulative irreversibilities from the overhead to thebottom. This presentation is equivalent to the Grassmann diagram. Full article

Other

Jump to: Research

Open AccessLetter Entropy of Relativistic Mono-Atomic Gas and Temperature Relativistic Transformation in Thermodynamics
Entropy 2007, 9(3), 113-117; doi:10.3390/e9030113
Received: 19 April 2007 / Accepted: 4 September 2007 / Published: 11 September 2007
Cited by 6 | PDF Full-text (170 KB) | HTML Full-text | XML Full-text
Abstract
It is demonstrated that the entropy of the ideal mono-atomic gas comprisingidentical spherical atoms is not conserved under the Planck-Einstein like relativistictemperature transformation, as a result of the change in the number of atomic degrees offreedom. This fact supports the idea that [...] Read more.
It is demonstrated that the entropy of the ideal mono-atomic gas comprisingidentical spherical atoms is not conserved under the Planck-Einstein like relativistictemperature transformation, as a result of the change in the number of atomic degrees offreedom. This fact supports the idea that there is no universal relativistic temperaturetransformation. Full article
Open AccessDiscussion On the So-Called Gibbs Paradox, and on the Real Paradox
Entropy 2007, 9(3), 132-136; doi:10.3390/e9030133
Received: 12 July 2007 / Accepted: 17 September 2007 / Published: 21 September 2007
Cited by 10 | PDF Full-text (210 KB)
Abstract Two versions of the so-called Gibbs paradox are discussed. Both of these areshown to be non-paradoxes. It is also shown that there is a different real paradox that emergesfrom Gibbs writings. Full article
(This article belongs to the Special Issue Gibbs Paradox and Its Resolutions)

Journal Contact

MDPI AG
Entropy Editorial Office
St. Alban-Anlage 66, 4052 Basel, Switzerland
entropy@mdpi.com
Tel. +41 61 683 77 34
Fax: +41 61 302 89 18
Editorial Board
Contact Details Submit to Entropy
Back to Top