1,720,962 research outputs found
Quantum Onsager-type equations from Bohm's potential
No full textTaking the Bohm potential approach, equations can be derived possessing QM information but classical form. Following this approach, an infinite set of equations for the infinite moments of the distribution function was derived, from which a PL approximation can be drawn at any order L. From the P1 approximation, Onsager-type equations are derived. They are QM equations insofar as: (1) they contain the Bohm potential; (2) collisional processes are described by the BUU kernel; (3) the equilibrium distribution functions are either FD or BE
QUANTUM MACROSCOPIC EQUATIONS FROM BOHM POTENTIAL AND PROPAGATION OF WAVES
No full textBohm’s interpretation of Quantum Mechanics leads to the derivation of a Quantum Kinetic Equation. In the present work, moments of this kinetic equation are taken, thus deriving conservation equations. These macroscopic equations are then applied to study the propagation of longitudinal density perturbations in neutral gases and plasmas, of either fermions or bosons. The dispersion relation is derived and the effect of Bohm’s potential shown; the speed of propagation calculated and the difference between fermions and bosons investigated
Distribution Function of Fusion Reaction Products and Entropy Evolution
No full textOne of the outcomes of nuclear reactions is that reaction products have at birth distribution functions far from Maxwellian. What role do those distribution functions play in the evolution of the entropy of the system? The purpose of this work is to show the effect of the distribution functions of reactant and reaction products on the entropy of a system undergoing DD nuclear fusion reactions. This analysis is conducted with the help of the H theorem, in the framework of kinetic theory. It will be found that at the onset of this reaction, generalized system entropy decreases markedly
Quantum relativistic distribution function for bosons and fermions
No full textIn the present work, quantum-relativistic equilibrium distribution functions are derived for bosons above the critical temperature and for weakly degenerate fermions, extending to the relativistic case the Bose-Einstein and Fermi-Dirac distributions
A DERIVATION OF QUANTUM KINETIC EQUATION FROM BOHM POTENTIAL
No full textIn Bohm’s interpretation of Quantum Mechanics, quantum effects are governed by a “quantum potential” (known as Bohm potential), and particles follow definite trajectories. In the present work, Liouville theorem is invoked, an appropriate Liouville equation is derived, and following the BBGKY method a quantum kinetic equation (QKE) is derived. To demonstrate the working of the QKE, two examples of application are presented: the thermal equilibrium of a quantum gas and the propagation of disturbances in a force free gas of non interacting bosons. In contrast to the classical collisionless Boltzmann equation, waves are found to be possible in the absence of interaction or external forces, due only to Bohm potential (zero sound propagation)
Extension of the Clausius inequality to quantum gases from a kinetic equation approach
Full text linkStarting from the appropriate quantum kinetic equation, with the
Boltzmann, Uehling and Uhlenbeck collision term, an expression is derived for the time evolution of entropy and, upon time integration, a corresponding entropy inequality is obtained valid for quantum systems of particles following either the Bose-Einstein, or the Fermi-Dirac statistics
Wave propagation and "Landau-type" damping from Bohm potential
No full textFrom Bohm’s interpretation of Quantum Mechanics, a quantum kinetic equation (QKE) can be derived. It is found that waves propagate in force-free gases of non interacting particles, only due to Bohm potential. In the present article the existence of Landau damping in such propagations is investigated. It is found that Bohm potential alone gives indeed rise to damping entirely analogous to classical Landau damping, both for bosons and for weakly degenerate fermions
Effect of Bohm potential on a charged gas
No full textBohm’s interpretation of Quantum Mechanics leads to the derivation of a Quantum Kinetic Equation (QKE): in the present work, propagation of waves in charged quantum gases is investigated starting from this QKE. Dispersion relations are derived for fully and weakly degenerate fermions and bosons (for the latter above critical temperature) and the differences discussed. Use of a kinetic equation permits investigation of “Landau-type” damping: it is found that the presence of damping in fermion gases is dependent upon the degree of degeneracy, whereas it is always present in boson gases. In fully degenerate fermions a phenomenon appears that is akin to the “zero sound” propagation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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