Results 1 - 10 of 15185
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[en] The dynamics of two atoms coupled to the vacuum radiation field is investigated within the framework of a one-dimensional model in the resonance dipole approximation. The exact solution of the resonance energy transfer problem is obtained. A many-atom generalization of the model is also discussed. (author)
[en] The edge viscosity of Caramana, Shashkov and Whalen is known to fail on the Noh problem in an initially rectangular grid. In this paper, we present a simple change that significantly improves the behavior in that case. We also show that added energy exchange between cells improves the symmetry of both edge viscosity and the tensor viscosity of Campbell and Shashkov. Finally, as suggested by Noh, this addition also reduces the wall heating effect.
[en] Graphical abstract: The picture shows directed excitation transfer along an engineered chain of monomers. Initially the excitation is coherently shared by two monomers. Research highlights: → Strong directionality of the energy transfer along a quantum aggregate is possible, depending on the initial state. → This can be achieved even for an initial excitation of only two monomers. → Coupling to a continuum of vibrations reduces the directionality. - Abstract: We investigate theoretically the transfer of excitation along a one dimensional chain of monomers for a situation in which initially the excitation is shared coherently by two monomers. We show that depending on the relative phase between the two monomers strong directionality of the energy transfer is possible. It is investigated how dephasing, induced by an environment, influences this directed transport.
[en] Dynamically Ordered self-organized dissipative structure exists in various forms and at different scales. This investigation first introduces the concept of an isolated embedding system, which embeds an open system, e.g., dissipative structure and its mass and/or energy exchange with its surroundings. Thereafter, scale-invariant theoretical analysis is presented using thermodynamic principles for Order creation, existence, and destruction. The sustainability criterion for Order existence based on its structured mass and/or energy interactions with the surroundings is mathematically defined. This criterion forms the basis for the interrelationship of physical parameters during sustained existence of dynamic Order. It is shown that the sufficient condition for dynamic Order existence is approached if its sustainability criterion is met, i.e., its destruction path is blocked. This scale-invariant approach has the potential to unify the physical understanding of universal dynamic ordering based on entropy considerations
[en] The extended Gaussian ensemble introduced recently as a generalization of the canonical ensemble, which allows to treat energy fluctuations present in the system, is used to analyze the inelasticity distributions in high energy multiparticle production processes. (authors)
[en] This paper introduces a postulate explicitly forbidding the extraction of an infinite amount of energy from a thermodynamic system. It also introduces the assumption that no measuring equipment is capable of detecting arbitrarily small energy exchanges. The Kelvin formulation of the second law is reinterpreted accordingly. Then statements related to both the unattainability version and the entropic version of the third law are derived. The value of any common thermodynamic potential of a one-component system at absolute zero of temperature is ascertained if some assumptions with regard to the state space can be made. The point of view is the phenomenological, macroscopic and non-statistical one of classical thermodynamics.
[en] The effect of vertical oscillations with periods between 90 s and 300 s on a solar atmosphere governed by heat conduction and radiation loss is examined. The effect is found to be primarily a redistribution, rather than a net addition or subtraction, of energy within the low corona, mainly by long period (180 to 300 s) oscillations. The redistribution of energy is found to affect the time-averaged temperature and density profiles of such an atmosphere, particularly in the low corona. The amount of energy redistributed is found to increase with increasing period. (orig.)