bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of a Thermoacoustic Engine with a Complex Heat Transfer Exponent
Authors: Wu Feng , Wu Chih , Guo Fangzhong , Li Qing , Chen Lingen
Published: October 2008

Heat transfer between a thermoacoustic engine and its surrounding heat reservoirs can be out of phase with oscillating working gas temperature. The paper presents a generalized heat transfer model using a complex heat transfer exponent. Both the real part and the imaginary part of the heat transfer exponent change the power versus efficiency relationship quantitatively. When the real part of the heat transfer exponent is fixed, the power output P decreases and the efficiency η increases along with increasing of the imaginary part. The Optimization zone on the performance of the thermoacoustic heat engine is obtained. The results obtained will be helpful for the further understanding and the selection of the optimal operating mode of the thermoacoustic heat engine.
Statistical and Physical Analysis of the External Factors Perturbation on Solar Radiation Exergy
Authors: Moreno Juan Carlos , Cañada Javier , Boscà José Vincente
Published: October 2008

The purpose of this paper is to analyze the external factor perturbations on solar radiation. Firstly, the influence on the photon distribution function in the space of frequencies is analyzed and, later, the modification generated in equations of internal energy, entropy, and radiation is viewed in order to deduce an expression to calculate the spectral exergy of perturbed radiation.
Convective Heating of Solid Surface: Entropy Generation Due to Temperature Field and Thermal Displacement
Authors: Al-Nassar Yagoub Nassar
Published: October 2008

Convective heating and cooling of the surfaces find application in process industry. During the heating or cooling cycle of the process, thermodynamic irreversibility which can be associated with the process parameters occurs. Moreover, thermodynamic irreversibility associated with the heating cycle can be quantified through entropy analysis. In the present study, convective heating of the solid surface is considered. A mathematical formulation of the temperature rise and thermal stress development during the transient heating process is presented. Entropy generation due to temperature field and thermal displacement is also formulated. The simulation for temperature rise, thermal displacement, and entropy generation are carried out for steel substrate. It is found that thermal displacement does not exactly follow the temperature distribution inside the substrate material. The magnitude of entropy generation due to temperature field is considerably higher than that corresponding to the thermal displacement.
Analytical Entropy Analysis of Recuperative Heat Exchangers
Authors: Galovic Antun , Virag Zdravko , Zivic Marija
Published: October 2008

The analytical solutions for the temperature variation of two streams in parallel flow, counter flow and cross-flow heat exchangers and related entropy generation due to heat exchange between the streams are presented. The analysis of limiting cases for the relative entropy generation is performed, and corresponding analytical expressions are given. The obtained results may be included in a more general procedure concerning optimal heat exchanger design.
An Analysis of The Entropy Generation in a Square Enclosure
Authors: Erbay Latife , Altaç Zekeriya , Sülüs Birsen
Published: October 2008

The entropy generation during transient laminar natural convection in a square enclosure is numerically investigated. Two different cases are considered. The enclosure is heated either completely or partially from the left side wall and cooled from the opposite side wall. The bottom and the top of the enclosure are assumed as insulated. The Boussinesq approximation is used in the natural convection modelling. The solutions are obtained from quiescent conditions proceeded through the transient up to the steady-state. The calculations are made for the Prandtl numbers 0.01 and 1.0 and Rayleigh numbers between 102-108. The entropy generation and the active places triggering the entropy generation are obtained for each case after the flow and thermal characteristics are determined. It is found that the active sites in the completely heated case are at the left bottom corner of the heated wall and the right top corner of the cooled wall at the same magnitudes. In the case of partial heating, however, the active site is observed at the top corner of the heated section especially at lower Pr and Ra values.
Entropy Generation During Fluid Flow Between Two Parallel Plates With Moving Bottom Plate
Authors: Erbay Latife , Ercan Mehmet , Sülüs Birsen , Yalçÿn M.
Published: October 2008

Two dimensional numerical analysis of entropy generation during transient convective heat transfer for laminar flow between two parallel plates has been investigated. The fluid is incompressible and Newtonian and the flow is the hydrodynamically and thermally developing. The plates are held at constant equal temperatures higher than that of the fluid. The bottom plate moves in either parallel or in inverse direction to the flow. The governing equations of the transient convective heat transfer are written in two-dimensional Cartesian coordinates and solved by the finite volume method with SIMPLE algorithm. The solutions are carried for Reynolds numbers of 102, 5x102 and 103 and Prandtl number of 1. After the flow field and the temperature distributions are obtained, the entropy values and the sites initiating the entropy generation are investigated. The results have indicated that the number of the entropy generation has its highest value at the highest Reynolds and Br/Ω values, which is obtained at counter motion of the lower plate. The lowest average number of the entropy generation on the bottom plate is obtained in parallel motion. The corners of the channel plates at the entrance play the role of active sites where the generation of entropy is triggered.
Effect of Heat Leak and Finite Thermal Capacity on the Optimal Configuration of a Two-Heat-Reservoir Heat Engine for Another Linear Heat Transfer Law
Authors: Zheng Tong , Chen Lingen , Sun Fengrui , Wu Chih
Published: October 2008

Based on a model of a two-heat-reservoir heat engine with a finite high-temperature source and bypass heat leak, the optimal configuration of the cycle is found for the fixed cycle period with another linear heat transfer law . The finite thermal capacity source without heat leak makes the configuration of the cycle to a class of generalized Carnot cycle. The configuration of the cycle with heat leak and finite thermal capacity source is different from others.
Special Issue on Quantum Limits to the Second Law of Thermodynamics
Authors: Nikulov Alexey , Sheehan Daniel
Published: October 2008

Over fifty years ago Arthur Eddington wrote [1]: “The second law of thermodynamics holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations – then so much the worse for Maxwell's equations. If it is found to be contradicted by observation, well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation”.[...]
A Collision Between Dynamics and Thermodynamics
Authors: Callender Craig
Published: October 2008

Philosophers of science have found the literature surrounding Maxwell's demon deeply problematic. This paper explains why, summarizing various philosophical complaints and adding to them. The first part of the paper critically evaluates attempts to exorcise Maxwell's demon; the second part raises foundational questions about some of the putative demons that are being summoned.
The Deep Physics Behind the Second Law: Information and Energy As Independent Forms of Bookkeeping
Authors: Duncan Todd L. , Semura Jack S.
Published: October 2008

Even after over 150 years of discussion, the interpretation of the second law of thermodynamics continues to be a source of confusion and controversy in physics. This confusion has been accentuated by recent challenges to the second law and by the difficulty in many cases of clarifying which formulation is threatened and how serious the implications of a successful challenge would be. To help bring clarity and consistency to the analysis of these challenges, the aim of this paper is to suggest a simple formulation of the deep physics of the second law, and to point out how such a statement might help us organize the challenges by level of seriousness. We pursue the notion that the second law is ultimately a restriction operating directly on the dynamics of information, so the existence of this law can be traced to the need for a system of "information bookkeeping" that is independent of the bookkeeping for energy. Energy and information are related but independent, so the dynamical restrictions for one cannot be derived from those for the other. From this perspective, we also suggest the possibility that the foundation of the second law may be linked to the finite capacity of nature to store bookkeeping information about its own state.
Thomson's formulation of the second law for macroscopic and finite work sources
Authors: Allahverdyan Armen E. , Balian Roger , Nieuwenhuizen Theo M.
Published: October 2008

Thomson's formulation of the second law states: no work can be extracted from an equilibrium system through a cyclic process. A simple, general proof is presented for the case of macroscopic sources of work. Next the setup is generalized towards situations, where the corresponding work-source is not macroscopic. It is shown that using such a source one can extract energy from an equilibrium system by means of a cyclic process. However, this extraction is accompanied by an entropy increase of the source, in a manner resembling the Clausius inequality.
The Decrease in Entropy via Fluctuations
Authors: Gordon Lyndsay G.M.
Published: October 2008

Classical and quantum aspects of fluctuations are reviewed in a discussion on the universality of the second law. Consideration is given to the need of information and the requirement of a ratchet and pawl-type mechanism for the utilization of energy from fluctuations. Some aspects of the quantum theory of the Copenhagen school are compared to those of Bohm within the discussion.
The adiabatic piston: a perpetuum mobile in the mesoscopic realm
Authors: Crosignani Bruno , Porto Paolo , Conti Claudio
Published: October 2008

A detailed analysis of the adiabatic-piston problem reveals, for a finely-tuned choice of the spatial dimensions of the system, peculiar dynamical features that challenge the statement that an isolated system necessarily reaches a time-independent equilibrium state. In particular, the piston behaves like a perpetuum mobile, i.e., it never comes to a stop but keeps wandering, undergoing sizeable oscillations around the position corresponding to maximum entropy; this has remarkable implications on the entropy changes of a mesoscopic isolated system and on the limits of validity of the second law of thermodynamics in the mesoscopic realm.
Langevin approach to the Porto system
Authors: Bok Jirí , Cápek Vladislav
Published: October 2008

M. Porto (Phys. Rev. E 63 (2001) 030102) suggested a system consisting of Coulomb interacting particles, forming a linear track and a rotor, and working as a molecular motor. Newton equations with damping for the rotor coordinate on the track x, with a prescribed time-dependence of the rotor angle Θ, indicated unidirectional motion of the rotor. Here, for the same system, the treatment was generalized to nonzero temperatures by including stochastic forces and treating both x and Θ via two coupled Langevin equations. Numerical results are reported for stochastic homogeneous distributions of impact events and Gaussian distributions of stochastic forces acting on both the variables. For specific values of parameters involved, the unidirectional motion of the rotor along the track is confirmed, but with a mechanism that is not necessarily the same as that one by Porto. In an additional weak homogeneous potential field U(x)=const.x acting against the motion, the unidirectional motion persists. Then the rotor accumulates potential energy at the cost of thermal stochastic forces from the bath.
From Randomness to Order
Authors: Berger Jorge
Published: October 2008

I review some selected situations in which order builds up from randomness, or a losing trend turns into winning. Except for Section 4 (which is mine), all cases are well documented and the price paid to achieve order is apparent.
Modified Feynman ratchet with velocity-dependent fluctuations
Authors: Denur Jack
Published: October 2008

The randomness of Brownian motion at thermodynamic equilibrium can be spontaneously broken by velocity-dependence of fluctuations, i.e., by dependence of values or probability distributions of fluctuating properties on Brownian-motional velocity. Such randomness-breaking can spontaneously obtain via interaction between Brownian-motional Doppler effects --- which manifest the required velocity-dependence --- and system geometrical asymmetry. A non random walk is thereby spontaneously superposed on Brownian motion, resulting in a systematic net drift velocity despite thermodynamic equilibrium. The time evolution of this systematic net drift velocity --- and of velocity probability density, force, and power output --- is derived for a velocity-dependent modification of Feynman's ratchet. We show that said spontaneous randomness-breaking, and consequent systematic net drift velocity, imply: bias from the Maxwellian of the system's velocity probability density, the force that tends to accelerate it, and its power output. Maximization, especially of power output, is discussed. Uncompensated decreases in total entropy, challenging the second law of thermodynamics, are thereby implied.
A Maxwellian Valve based on centrifugal forces
Authors: Gordon Lyndsay G.M.
Published: October 2008

A mechanism is described which can create a chemical potential gradient from a single heat reservoir. The mechanism is equivalent to a Maxwellian valve. Heat supplies the energy through thermal fluctuations to form the gradient contrary to the second law. A quantitative analysis of the system is given.
Smoluchowski's Trapdoor
Authors: Gordon Lyndsay G.M.
Published: October 2008

A mechanism of a gated pore in a membrane is described. Fluxes of gas molecules pass through the pore and produce a pressure gradient in a process that challenges the second law.
A Modified Szilard's Engine: Measurement, Information, and Maxwell's Demon
Authors: Devereux Michael
Published: October 2008

Using an isolated measurement process, I've calculated the effect measurement has on entropy for the multi-cylinder Szilard engine. This calculation shows that the system of cylinders possesses an entropy associated with cylinder total energy states, and that it records information transferred at measurement. Contrary to other's results, I've found that the apparatus loses entropy due to measurement. The Second Law of Thermodynamics may be preserved if Maxwell's demon gains entropy moving the engine partition.
Second Law Violation By Magneto-Caloric Effect Adiabatic Phase Transition of Type I Superconductive Particles
Authors: Keefe Peter
Published: October 2008

The nature of the thermodynamic behavior of Type I superconductor particles, having a cross section less than the Ginzburg-Landau temperature dependent coherence length is discussed for magnetic field induced adiabatic phase transitions from the superconductive state to the normal state. Argument is advanced supporting the view that when the adiabatic magneto-caloric process is applied to particles, the phase transition is characterized by a decrease in entropy in violation of traditional formulations of the Second Law, evidenced by attainment of a final process temperature below that which would result from an adiabatic magneto-caloric process applied to bulk dimensioned specimens.
A Concise Equation of State for Aqueous Solutions of Electrolytes Incorporating Thermodynamic Laws and Entropy
Authors: Heyrovská Raji
Published: October 2008

Recently, the author suggested a simple and composite equation of state by incorporating fundamental thermodynamic properties like heat capacities into her earlier concise equation of state for gases based on free volume and molecular association / dissociation. This work brings new results for aqueous solutions, based on the analogy of the equation of state for gases and solutions over wide ranges of pressures (for gases) and concentrations (for solutions). The definitions of entropy and heat energy through the equation of state for gases, also holds for solutions.
Delocalization and Sensitivity of Quantum Wavepacket in Coherently Perturbed Kicked Anderson Model
Authors: Yamada Hiroaki
Published: October 2008

We consider quantum diffusion of the initially localized wavepacket in one-dimensional kicked disordered system with classical coherent perturbation. The wavepacket localizes in the unperturbed kicked Anderson model. However, the wavepacket get delocalized even by coupling with monochromatic perturbation. We call the state "dynamically delocalized state". It is numerically shown that the delocalized wavepacket spread obeying diffusion law, and the perturbation strength dependence of the diffusion rate is given. The sensitivity of the delocalized state is also shown by the time-reversal experiment after random change in phase of the wavepacket. Moreover, it is found that the diffusion strongly depend on the initial phase of the perturbation. We discuss a relation between the "classicalization" of the quantum wave packet and the time-dependence of the initial phase dependence. The complex structure of the initial phase dependence is related to the entropy production in the quantum system.
Entropic localization in non-unitary Newtonian gravity
Authors: Filippo Sergio , Maimone Filippo
Published: October 2008

The localizing properties and the entropy production of the Newtonian limit of a nonunitary version of fourth order gravity are analyzed. It is argued that pure highly unlocalized states of the center of mass motion of macroscopic bodies rapidly evolve into unlocalized ensembles of highly localized states. The localization time and the final entropy are estimated.
A New Thermodynamics from Nuclei to Stars
Authors: Gross Dieter H.E.
Published: October 2008

Equilibrium statistics of Hamiltonian systems is correctly described by the microcanonical ensemble. Classically this is the manifold of all points in the N-body phase space with the given total energy. Due to Boltzmann's principle, eS=tr(δ(E-H)), its geometrical size is related to the entropy S(E,N,...). This definition does not invoke any information theory, no thermodynamic limit, no extensivity, and no homogeneity assumption, as are needed in conventional (canonical) thermo-statistics. Therefore, it describes the equilibrium statistics of extensive as well of non-extensive systems. Due to this fact it is the fundamental definition of any classical equilibrium statistics. It can address nuclei and astrophysical objects as well. All kind of phase transitions can be distinguished sharply and uniquely for even small systems. It is further shown that the second law is a natural consequence of the statistical nature of thermodynamics which describes all systems with the same -- redundant -- set of few control parameters simultaneously. It has nothing to do with the thermodynamic limit. It even works in systems which are by far than any thermodynamic "limit".
Markov Property and Operads
Authors: Léandre Rémi
Published: October 2008

We define heat kernel measure on punctured spheres. The random field which is got by this procedure is not Gaussian. We define a stochastic line bundle on the loop space, such that the punctured sphere corresponds to a generalized parallel transport on this line bundle. Markov property along the sewing loops corresponds to an operadic structure of the stochastic W.Z.N.W. model.
On Expansion of a Spherical Enclosure Bathed in Zero-Point Radiation
Authors: Mares Jirí , Spicka Václav , Kristofik Jozef , Hubik Pavel
Published: October 2008

In the present contribution a simple thought experiment made with an idealized spherical enclosure bathed in zero-point (ZP) electromagnetic radiation and having walls made of a material with an upper frequency cut-off has been qualitatively analysed. As a result, a possible mechanism of filling real cavities with ZP radiation based on Doppler's effect has been suggested and corresponding entropy changes have been discussed.
Internal Structure of Elementary Particle and Possible Deterministic Mechanism of Biological Evolution
Authors: Melkikh Alexei V.
Published: October 2008

The possibility of a complicated internal structure of an elementary particle was analyzed. In this case a particle may represent a quantum computer with many degrees of freedom. It was shown that the probability of new species formation by means of random mutations is negligibly small. Deterministic model of evolution is considered. According to this model DNA nucleotides can change their state under the control of elementary particle internal degrees of freedom.
The Stability Limits of the Surface Phases at the Polarized Interface of a Liquid Electrode with an Electrolyte Solution
Authors: Kuklin Rudolf  N.
Published: October 2008

The thermodynamic stability limits of specific adsorption at the polarized liquid metal/ electrolyte solution interface are studied. Here the reversible starting and disappearance of the electroadsorption effects at a threshold potential are revealed, which are the result of Gibbs stability violation. The stability limits are determined by the bifurcation manifold of the critical states for which determinant of matrix of a second differential of the surface pressure equals zero. The equations of the critical states are equivalent to the spinodal equations used in the theory of phase transitions. The conception developed beneath will help provide to interpretate the anomalies of electrocapillary effects through the catastrophe theory.
Optimum Criteria on the Performance of an Irreversible Braysson Heat Engine Based on the new Thermoeconomic Approach
Authors: Tyagi Sudhir Kumar , Zhou Yinghui , Chen Jincan
Published: October 2008

An irreversible cycle model of a Braysson heat engine operating between two heat reservoirs is used to investigate the thermoeconomic performance of the cycle affected by the finite-rate heat transfer between the working fluid and the heat reservoirs, heat leak loss from the heat source to the ambient and the irreversibility within the cycle. The thermoeconomic objective function, defined as the total cost per unit power output, is minimized with respect to the cycle temperatures along with the isobaric temperature ratio for a given set of operating parameters. The objective function is found to be an increasing function of the internal irreversibility parameter, economic parameters and the isobaric temperature ratio. On the other hand, there exist the optimal values of the state point temperatures, power output and thermal efficiency at which the objective function attains its minimum for a typical set of operating parameters. Moreover, the objective function and the corresponding power output are also plotted against the state point temperature and thermal efficiency for a different set of operating parameters. The optimally operating regions of these important parameters in the cycle are also determined. The results obtained here may provide some useful criteria for the optimal design and performance improvements, from the point of view of economics as well as from the point of view of thermodynamics of an irreversible Braysson heat engine cycle and other similar cycles as well.
Statistical Convergent Topological Sequence Entropy Maps of the Circle
Authors: Aydin Bünyamin
Published: October 2008

A continuous map f of the interval is chaotic iff there is an increasing of nonnegative integers T such that the topological sequence entropy of f relative to T, hT(f), is positive [4]. On the other hand, for any increasing sequence of nonnegative integers T there is a chaotic map f of the interval such that hT(f)=0 [7]. We prove that the same results hold for maps of the circle. We also prove some preliminary results concerning statistical convergent topological sequence entropy for maps of general compact metric spaces.
Entropy Production and Irreversible Processes -from the perspective of continuous topological evolution.
Authors: Kiehn Robert  M.
Published: October 2008

A concept of entropy production associated with continuous topological evolution is deduced (without statistics) from the fact that Cartan-Hilbert 1-form of Action defines a non-equilibrium symplectic system of Pfaff Topological dimension 2n+2. The differential entropy, dS, is composed of the interior product of the non-canonical components of momentum with the components of the differential velocities. An irreversible process can describe entropy production in terms of continuous topological evolution to non-equilibrium but stationary states. An equilibrium system can be defined topologically as a Lagrange submanifold of the 2n+2 topological space, upon which the change in entropy by continuous topological evolution is zero, dSequil=0.
Effect of Magnetic Field on Entropy Generation Due to Laminar Forced Convection Past a Horizontal Flat Plate
Authors: Al-Odat Mohammed  Q. , Damseh Renhe  A. , Al-Nimr Moh'd  A.
Published: October 2008

Magnetic field effect on local entropy generation due to steady two-dimensional laminar forced convection flow past a horizontal plate was numerically investigated. This study was focused on the entropy generation characteristics and its dependency on various dimensionless parameters. The effect of various dimensionless parameters, such as Hartmann number (Ha), Eckert number (Ec), Prandtl number (Pr), Joule heating parameter (R) and the free stream temperature parameter (θ∞) on the entropy generation characteristics is analyzed. The dimensionless governing equations in Cartesian coordinate were solved by an implicit finite difference technique. The solutions were carried out for Ha2=0.5-3, Ec=0.01-0.05, Pr=1-5 and θ∞=1.1-2.5. It was found that, the entropy generation increased with increasing Ha, Ec and R. While, increasing the free stream temperature parameter, and Prandtl number tend to decrease the local entropy generation.
Entropy Analysis for Non-Newtonian Fluid Flow in Annular Pipe: Constant Viscosity Case
Authors: Yilbas Bekir  Sami , Yürüsoy Muhammet , Pakdemirli Mehmet
Published: October 2008

In the present study, non-Newtonian flow in annular pipe is considered. The analytical solution for velocity and temperature fields is presented while entropy generation due to fluid friction and heat transfer is formulated. The third grade fluid with constant properties is accommodated in the analysis. It is found that reducing non-Newtonian parameter increases maximum velocity magnitude and maximum temperature in the annular pipe. Total entropy generation number attains high values in the region close to the inner wall of the annular pipe, which becomes significant for low non-Newtonian parameters. Increasing Brinkman number enhances entropy generation number, particularly in the region close to the annular pipe inner wall.
Optimal Cooling Load and COP Relationship of a Four-Heat-Reservoir Endoreversible Absorption Refrigeration Cycle
Authors: Chen Lingen , Zheng Tong , Sun Fengrui , Wu Chih
Published: October 2008

On the basis of a four-heat-reservoir endoreversible absorption refrigeration cycle model, another linear heat transfer law [i.e., the heat-flux] is adopted, the fundamental optimal relation between the coefficient of performance (COP) and the cooling load, as well as the maximum cooling load and the corresponding COP of the cycle coupled to constant-temperature heat reservoirs are derived by using finite-time thermodynamics or thermodynamic optimization. The optimal distribution of the heat-transfer surface areas is also obtained. Moreover, the effects of the cycle parameters on the COP and the cooling load of the cycle are studied by detailed numerical examples. The results obtained herein are of importance to the optimal design and performance improvement of an absorption refrigeration cycle.
The Spontaneous Origin of New Levels in a Scalar Hierarchy
Authors: Salthe Stanley  N.
Published: October 2008

Given a background of universal thermodynamic disequilibrium, I suggest that the interpolation of new levels in a material scale hierarchy is favored when the entropy production of a local region would be increased by such structural complexification. This would involve the separation by order of magnitude of the average dynamical rate of the new level compared to those of the resulting contiguous levels from which it became disentangled, thereby facilitating laminar flows. Here the Second Law of thermodynamics is understood as a final cause, which can be expressed in this creative way when the surrounding superstructure has a form allowing it to mediate this change (by, e.g., focusing kinetics, etc.), and given, as well, sufficiently differentiated local energy gradients to materially support the increased local dissipation.
Thermal Analysis in Pipe Flow: Influence of Variable Viscosity on Entropy Generation
Authors: Al-Zaharnah Iyad  Talal , Yilbas Bekir  Sami
Published: October 2008

Flow through pipes and heating situations find wide applications in industry. Depending on the fluid properties, temperature field in the pipe changes. This in turn results in thermodynamic irreversibility in the flow system. Thermodynamic irreversibility can be quantified through amount of entropy generation in the thermal system. Consequently, in the present study, the influence of fluid viscosity on the entropy generation due to pipe flow heated from the pipe wall at constant temperature is examined. The turbulent flow with conjugate heating situation is accommodated in the analysis. The governing equations of flow and heat transfer are solved numerically using a control volume approach. Entropy generation rate due to different pipe wall temperatures is computed. It is found that the volumetric entropy generation rate in the pipe is higher for variable properties case; however, total entropy generation rate in the pipe wall attains considerably lower values for variable viscosity case as compared to that corresponding to the constant viscosity case.
On a simple derivation of a family of nonextensive entropies from information content
Authors: Yamano Takuya
Published: October 2008

The nonextensive entropy of Tsallis can be seen as a consequence of postulates on a self-information, i.e., the constant ratio of the first derivative of a self-information per unit probability to the curvature (second variation) of it. This constancy holds if we regard the probability distribution as the gradient of a self-information. Considering the form of the nth derivative of a self-information with keeping this constant ratio, we arrive at the general class of nonextensive entropies. Some properties on the series of entropies constructed by this picture are investigated.
On The Use of Entropy to Predict Boundary Layer Stability
Authors: Walsh Ed  J. , Davies Mark  R.D. , McEligot Donald   M.
Published: October 2008

Boundary layer transition is a critical parameter in the design of fluid flow systems. This situation is due to the dramatic change in both entropy production and heat transfer that accompanies it. It is well recognized that many parameters affect the location of transition onset, however, no models exist which unify all these parameters. This paper presents a new hypothesis that the driving force of boundary layer transition onset is the entropy generation rate alone, with all other parameters being functions of this higher order quantity. At present this hypothesis is speculative, but encouraging since good compatibility is found with more established transition models.
An Alternative to Entropy in the Measurement of Information
Authors: Schroeder Marcin  J.
Published: October 2008

Entropy has been the main tool in the analysis of the concept of information since information theory was conceived in the work of Shannon more than fifty years ago. There were some attempts to find more general measure of information, but their outcomes were more of formal, theoretical interest, and neither has provided better insight into the nature of information. The strengths of entropy seemed so obvious that no much effort has been made to find an alternative to entropy which gives different values, but which is consistent with entropy in the sense that the results obtained in information theory thus far can be reproduced with the new measure. In this article the need for such an alternative measure is demonstrated based on historical review of the problems with conceptualization of information. Then, an alternative measure is presented in the context of modified definition of information applicable outside of the conduit metaphor of Shannon's approach, and formulated without reference to uncertainty. It has several features superior to those of entropy. For instance, unlike entropy it can be easily and consistently extended to the continuous probability distributions, and unlike differential entropy this extension is always positive and invariant with respect to linear transformations of coordinates.
Entropy Generation Due to Laminar Incompressible Forced Convection Flow Through Parallel-Plates Microchannel
Authors: Haddad Osamah , Abuzaid Mohammad , Al-Nimr Mohammad
Published: October 2008

The entropy generation due to steady laminar forced convection fluid flow through parallel plates microchannel is investigated numerically. The effect of Knudsen, Reynolds, Prandtl, Eckert numbers and the nondimensional temperature difference on entropy generation within the microchannel is discussed. The fraction of the entropy generation due to heat transfer to the total entropy generation within the microchannel is studied in terms of Bejan number. The entropy generation within the microchannel is found to decrease as Knudsen number increases, and it is found to increase as Reynolds, Prandtl, Eckert numbers and the nondimensional temperature difference increase. The contribution of the viscous dissipation in the total entropy generation increases as Knudsen number increases over wide ranges of the flow controlling parameters.
Lagrangian submanifolds generated by the Maximum Entropy principle
Authors: Favretti Marco
Published: October 2008

We show that the Maximum Entropy principle (E.T. Jaynes, [8]) has a natural description in terms of Morse Families of a Lagrangian submanifold. This geometric approach becomes useful when dealing with the M.E.P. with nonlinear constraints. Examples are presented using the Ising and Potts models of a ferromagnetic material.
The entropy of a mixture of probability distributions
Authors: Vos Alexis
Published: October 2008

If a message can have n different values and all values are equally probable, then the entropy of the message is log(n). In the present paper, we investigate the expectation value of the entropy, for arbitrary probability distribution. For that purpose, we apply mixed probability distributions. The mixing distribution is represented by a point on an infinite dimensional hypersphere in Hilbert space. During an `arbitrary' calculation, this mixing distribution has the tendency to become uniform over a flat probability space of ever decreasing dimensionality. Once such smeared-out mixing distribution is established, subsequent computing steps introduce an entropy loss expected to equal $\\frac{1}{m+1} + \\frac{1}{m+2} + ... + \\frac{1}{n}$, where n is the number of possible inputs and m the number of possible outcomes of the computation.
Numerical Study On Local Entropy Generation In Compressible Flow Through A Suddenly Expanding Pipe
Authors: Yapici Hüseyin , Kayatas Nesrin , Kahraman Nafiz , Bastürk Gamze
Published: October 2008

This study presents the investigation of the local entropy generation in compressible flow through a suddenly expanding pipe. Air is used as fluid. The air enters into the pipe with a turbulent profile using 1/7 th power law. The simulations are extended to include different expansion ratios reduced gradually from 5 to 1. To determine the effects of the mass flux, φ" the ambient heat transfer coefficient, hamb, and the inlet temperature, Tin, on the entropy generation rate, the compressible flow is examined for various cases of these parameters. The flow and temperature fields are computed numerically with the help of the Fluent computational fluid dynamics (CFD) code. In addition to this CFD code, a computer program has been developed to calculate numerically the entropy generation and other thermodynamic parameters by using the results of the calculations performed for the flow and temperature fields. The values of thermodynamic parameters in the sudden expansion. (SE) case are normalized by dividing by their base quantities obtained from the calculations in the uniform cross-section (UC) case. The contraction of the radius of the throat (from 0.05 to 0.01 m) increases significantly the maximum value of the volumetric entropy generation rate, (about 60%) and raises exponentially 11 times the total entropy generation rate with respect to the its base value. The normalized merit number decreases 73% and 40% with the contraction of the cross-section and with the increase of the ambient heat transfer coefficient (from 20 to 100 W/m2-K), respectively, whereas it rises 226% and 43% with the decrease of the maximum mass flux (from 5 to 1 kg/m2-s) and with the increase of the inlet temperature (from 400 to 1000 K), respectively. Consequently, the useful energy transfer rate to irreversibility rate improves as the mass flux decreases and as the inlet temperature increases.
The meanings of entropy
Authors: Brissaud Jean-Bernard
Published: October 2008

Entropy is a basic physical quantity that led to various, and sometimes apparently conflicting interpretations. It has been successively assimilated to different concepts such as disorder and information. In this paper we're going to revisit these conceptions, and establish the three following results: Entropy measures lack of information; it also measures information. These two conceptions are complementary. Entropy measures freedom, and this allows a coherent interpretation of entropy formulas and of experimental facts. To associate entropy and disorder implies defining order as absence of freedom. Disorder or agitation is shown to be more appropriately linked with temperature.
Physical Premium Principle: A New Way for Insurance Pricing
Authors: Darooneh Amir   H.
Published: October 2008

In our previous work we suggested a way for computing the non-life insurance premium. The probable surplus of the insurer company assumed to be distributed according to the canonical ensemble theory. The Esscher premium principle appeared as its special case. The difference between our method and traditional principles for premium calculation was shown by simulation. Here we construct a theoretical foundation for the main assumption in our method, in this respect we present a new (physical) definition for the economic equilibrium. This approach let us to apply the maximum entropy principle in the economic systems. We also extend our method to deal with the problem of premium calculation for correlated risk categories. Like the Buhlman economic premium principle our method considers the effect of the market on the premium but in a different way.
Van der Waals gas as working substance in a Curzon and Ahlborn-Novikov engine
Authors: Ladino-Luna Delfino
Published: October 2008

Using a van der Waals gas as the working substance the so called Curzon and Ahlborn-Novikov engine is studied. It is shown that some previous results found in the literature of finite time thermodynamics can be written in a more general form, means of this gas and by taking a non linear heat transfer law.
Basis of Local Approach in Classical Statistical Mechanics
Authors: Sharov Sergey   R.
Published: October 2008

An ensemble of classical subsystems interacting with surrounding particles has been considered. In general case, a phase volume of the subsystems ensemble was shown to be a function of time. The evolutional equations of the ensemble are obtained as well as the simplest solution of these equations representing the quasi-local distribution with the temperature pattern being assigned. Unlike the Gibbs's distribution, the energy of interaction with surrounding particles appears in the distribution function, which make possible both evolution in the equilibrium case and fluctuations in the non-equilibrium one. The expression for local entropy is obtained. The derivation of hydrodynamic equations from Boltzmann equation has been analyzed. The hydrodynamic equations obtained from Boltzmann equation were shown to be equations for ideal liquid. Reasons for stochastic description in deterministic Hamilton's systems, conditions of applicability of Poincare's recurrence theorem as well as the problem of irreversibility have been considered.
On the Entropy Production Due to Explosion in Seawater
Authors: Yadav R. P. , Agarwal P. K. , Sharma Atul
Published: October 2008

The change in entropy is calculated due to propagation of blast waves, produced by the explosion of spherical charge in sea water, using the energy hypothesis of Thomas. The release of energy is considered as instantaneous and the gravitation of earth is taken into account, assuming the earth to be a sphere of uniform density. For the sake of simplicity, effect of rotation of the earth is not considered. The explosion is considered at different depths. It has been found that the change in entropy of water decreases at different radial points, as the shock moves away from the point of explosion. Explosion occurred at larger depths, produces a smaller change in entropy of water, then the explosion of same energy, at smaller depths. Directional dependence of entropy production and the motion of the shock are also studied. It has been found that, entropy production is larger in upward motion of the underwater shock. However the shock velocity increases in downward direction.
Second Law Analysis of Laminar Flow In A Channel Filled With Saturated Porous Media
Authors: Makinde O. D. , Osalusi E.
Published: October 2008

The entropy generation rate in a laminar flow through a channel filled with saturated porous media is investigated. The upper surface of the channel is adiabatic and the lower wall is assumed to have a constant heat flux. The Brinkman model is employed. Velocity and temperature profiles are obtained for large Darcy number (Da) and used to obtain the entropy generation number and the irreversibility ratio. Generally, our result shows that heat transfer irreversibility dominates over fluid friction irreversibility (i.e. 0 < ø < 1), and viscous dissipation has no effect on the entropy generation rate at the centerline of the channel.
On the Linear Combination of Exponential and Gamma Random Variables
Authors: Nadarajah Saralees , Kotz Samuel
Published: October 2008

The exact distribution of the linear combination α X + β Y is derived when X and Y are exponential and gamma random variables distributed independently of each other. A measure of entropy of the linear combination is investigated. We also provide computer programs for generating tabulations of the percentage points associated with the linear combination. The work is motivated by examples in automation, control, fuzzy sets, neurocomputing and other areas of computer science.
Exergy Analysis and Second Law Efficiency of a Regenerative Brayton Cycle with Isothermal Heat Addition
Authors: Jubeh Naser   M.
Published: October 2008

The effect of two heat additions, rather than one, in a gas turbine engine is analyzed from the second law of thermodynamics point of view. A regenerative Brayton cycle model is used for this study, and compared with other models of Brayton cycle. All fluid friction losses in the compressor and turbine are quantified by an isentropic efficiency term. The effect of pressure ratio, turbine inlet temperature, ambient temperature, altitude, and altitude with variable ambient temperature on irreversibility "exergy destroyed" and second law efficiency was investigated and compared for all models. The results are given graphically with the appropriate discussion and conclusion.
The FIS2005 Conference in Paris
Authors: Petitjean Michel
Published: October 2008

The FIS2005 - Third Conference on the Foundations of Information Science - has been held in Paris, 4-7 July 2005.[...]
Entropy, Fluctuation Magnified and Internal Interactions
Authors: Chang Yi-Fang
Published: October 2008

Since fluctuations can be magnified due to internal interactions under a certain condition, the equal-probability does not hold. The entropy would be defined as S(t)=-k Σr Pr(t) ln Pr(t). From this or S=k ln Ω in an internal condensed process, possible decrease of entropy is calculated. Internal interactions, which bring about inapplicability of the statistical independence, cause possibly decreases of entropy in an isolated system. This possibility is researched for attractive process, internal energy, system entropy and nonlinear interactions, etc. An isolated system may form a self-organized structure probably.
Remarks on the Compatibility of Opposite Arrows of Time
Authors: Zeh H. D.
Published: October 2008

I argue that opposite arrows of time, while being logically possible, cannot realistically be assumed to exist during one and the same epoch of our universe.
Two-way thermodynamics: Could it really happen?
Authors: Schulman L. S.
Published: October 2008

In previous publications I have suggested that opposite thermodynamic arrows of time could coexist in our universe. This letter responds to the comments of H. D. Zeh (previous letter in this journal).
A Computer's Arrow of Time
Authors: Schulman L. S.
Published: October 2008

Some researchers believe that the psychological or consciousness arrow of time is a consequence of the thermodynamic arrow. Some don't. As for many issues in this area, the disagreement revolves about fundamental and undebatable assumptions. As a contribution to this standoff I consider the extent to which a computer---presumably governed by nothing more than the thermodynamic arrow---can be said to possess a psychological arrow. My contention is that the parallels are sufficiently strong as to leave little room for an independent psychological arrow. Reservations are nevertheless expressed on the complete objectivity of the thermodynamic arrow.
Numerical Prediction of Entropy Generation in Separated Flows
Authors: Abu-Nada Eiyad
Published: October 2008

The present research investigates second law analysis of laminar flow over a backward facing step (BFS). Entropy generation due to separation, reattachment, recirculation and heat transfer is studied numerically. Local entropy generation distributions were obtained by solving momentum, energy, and entropy generation equations. The effect of dimensionless temperature difference number (τ) and Brinkman number (Br) on the total entropy generation number (Ns) was investigated. Moreover, the effect of Reynolds number (Re) on the value of Ns was reported. It was found that as Re increased the value of Ns increased. Also, as Br increased the value of Ns increased. However, it was found that as τ increased the value of Ns decreased. For the bottom wall of the channel, the maximum value of Ns occurs inside the recirculation zone and reduces to a minimum value at the point of reattachment point. Also, for Re ≥ 500, a second peak of entropy generation appears after the reattachment point. For the top wall of the channel, the value of Ns has a maximum value directly above the step and its value reduced downstream the step. The contribution of the top wall to Ns downstream the point of reattachment was relatively small.