610,259 research outputs found

    The Zeroth Law of Thermodynamics and Volume-Preserving Conservative Dynamics with Equilibrium Stochastic Damping

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    We propose a mathematical formulation of the zeroth law of thermodynamics and develop a stochastic dynamical theory, with a consistent irreversible thermodynamics, for systems possessing sustained conservative stationary current in phase space while in equilibrium with a heat bath. The theory generalizes underdamped mechanical equilibrium: dx=gdt+{Dϕdt+2DdB(t)}dx=gdt+\{-D\nabla\phi dt+\sqrt{2D}dB(t)\}, with g=0\nabla\cdot g=0 and {}\{\cdots\} respectively representing phase-volume preserving dynamics and stochastic damping. The zeroth law implies stationary distribution uss(x)=eϕ(x)u^{ss}(x)=e^{-\phi(x)}. We find an orthogonality ϕg=0\nabla\phi\cdot g=0 as a hallmark of the system. Stochastic thermodynamics based on time reversal (t,ϕ,g)(t,ϕ,g)\big(t,\phi,g\big)\rightarrow\big(-t,\phi,-g\big) is formulated: entropy production ep#(t)=dF(t)/dte_p^{\#}(t)=-dF(t)/dt; generalized "heat" hd#(t)=dU(t)/dth_d^{\#}(t)=-dU(t)/dt, U(t)=Rnϕ(x)u(x,t)dxU(t)=\int_{\mathbb{R}^n} \phi(x)u(x,t)dx being "internal energy", and "free energy" F(t)=U(t)+Rnu(x,t)lnu(x,t)dxF(t)=U(t)+\int_{\mathbb{R}^n} u(x,t)\ln u(x,t)dx never increases. Entropy follows dSdt=ep#hd#\frac{dS}{dt}=e_p^{\#}-h_d^{\#}. Our formulation is shown to be consistent with an earlier theory of P. Ao. Its contradistinctions to other theories, potential-flux decomposition, stochastic Hamiltonian system with even and odd variables, Klein-Kramers equation, Freidlin-Wentzell's theory, and GENERIC, are discussed.Comment: 25 page

    Thermodynamic Limit in Statistical Physics

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    The thermodynamic limit in statistical thermodynamics of many-particle systems is an important but often overlooked issue in the various applied studies of condensed matter physics. To settle this issue, we review tersely the past and present disposition of thermodynamic limiting procedure in the structure of the contemporary statistical mechanics and our current understanding of this problem. We pick out the ingenious approach by N. N. Bogoliubov, who developed a general formalism for establishing of the limiting distribution functions in the form of formal series in powers of the density. In that study he outlined the method of justification of the thermodynamic limit when he derived the generalized Boltzmann equations. To enrich and to weave our discussion, we take this opportunity to give a brief survey of the closely related problems, such as the equipartition of energy and the equivalence and nonequivalence of statistical ensembles. The validity of the equipartition of energy permits one to decide what are the boundaries of applicability of statistical mechanics. The major aim of this work is to provide a better qualitative understanding of the physical significance of the thermodynamic limit in modern statistical physics of the infinite and "small" many-particle systems.Comment: 28 pages, Refs.180. arXiv admin note: text overlap with arXiv:1011.2981, arXiv:0812.0943 by other author

    Design of engineering systems in Polish mines in the third quarter of the 20th century

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    Participation of mathematicians in the implementation of economic projects in Poland, in which mathematics-based methods played an important role, happened sporadically in the past. Usually methods known from publications and verified were adapted to solving related problems. The subject of this paper is the cooperation between mathematicians and engineers in Wroc{\l}aw in the second half of the twentieth century established in the form of an analysis of the effectiveness of engineering systems used in mining. The results of this cooperation showed that at the design stage of technical systems it is necessary to take into account factors that could not have been rationally controlled before. The need to explain various aspects of future exploitation was a strong motivation for the development of mathematical modeling methods. These methods also opened research topics in the theory of stochastic processes and graph theory. The social aspects of this cooperation are also interesting.Comment: 45 pages, 11 figures, 116 reference

    Towards MKM in the Large: Modular Representation and Scalable Software Architecture

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    MKM has been defined as the quest for technologies to manage mathematical knowledge. MKM "in the small" is well-studied, so the real problem is to scale up to large, highly interconnected corpora: "MKM in the large". We contend that advances in two areas are needed to reach this goal. We need representation languages that support incremental processing of all primitive MKM operations, and we need software architectures and implementations that implement these operations scalably on large knowledge bases. We present instances of both in this paper: the MMT framework for modular theory-graphs that integrates meta-logical foundations, which forms the base of the next OMDoc version; and TNTBase, a versioned storage system for XML-based document formats. TNTBase becomes an MMT database by instantiating it with special MKM operations for MMT.Comment: To appear in The 9th International Conference on Mathematical Knowledge Management: MKM 201

    Abstract State Machines 1988-1998: Commented ASM Bibliography

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    An annotated bibliography of papers which deal with or use Abstract State Machines (ASMs), as of January 1998.Comment: Also maintained as a BibTeX file at http://www.eecs.umich.edu/gasm

    Variational Principle of Bogoliubov and Generalized Mean Fields in Many-Particle Interacting Systems

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    The approach to the theory of many-particle interacting systems from a unified standpoint, based on the variational principle for free energy is reviewed. A systematic discussion is given of the approximate free energies of complex statistical systems. The analysis is centered around the variational principle of N. N. Bogoliubov for free energy in the context of its applications to various problems of statistical mechanics and condensed matter physics. The review presents a terse discussion of selected works carried out over the past few decades on the theory of many-particle interacting systems in terms of the variational inequalities. It is the purpose of this paper to discuss some of the general principles which form the mathematical background to this approach, and to establish a connection of the variational technique with other methods, such as the method of the mean (or self-consistent) field in the many-body problem, in which the effect of all the other particles on any given particle is approximated by a single averaged effect, thus reducing a many-body problem to a single-body problem. The method is illustrated by applying it to various systems of many-particle interacting systems, such as Ising and Heisenberg models, superconducting and superfluid systems, strongly correlated systems, etc. It seems likely that these technical advances in the many-body problem will be useful in suggesting new methods for treating and understanding many-particle interacting systems. This work proposes a new, general and pedagogical presentation, intended both for those who are interested in basic aspects, and for those who are interested in concrete applications.Comment: 60 pages, Refs.25
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