摘要:

The transport-theoretical analysis of pulsed-neutron experiments in polycrystalline moderators is performed in the space of functions square summable over infinite ranges in velocity and space variables. The possibility of the existence of discrete eigenvalues of the transport operator below the minimum collision rate is demonstrated.

ISSN:0041-1450    

DOI:10.1080/00411457208232530

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

One of us (C.G) has developed a transformation theory in nonequilibrium statistical mechanics that generalizes the usual transformation theory of quantum mechanics in the framework of the resolvent formalism of the Liouville-von Neumann operator extensively used by the Brussels school. Prigogine, George, and Henin have shown that the evolution of a dissipative system can be decomposed into separate subdynamics in orthogonal subspaces. The π subspace, containing all thermodynamics, can be seen as an extension of the subspace of the invariants in the absence of dissipation. In this subspace a suitable contracted description of the system can be given through a dressing operator χ, which has the property that HR= χ−1H0can be considered as the renormalized energy. A differential equation that determines χ has been proposed by Mandel. It is useful to see, even for a nondissipative system, what relation the transformation theory in the Liouville-von Neumann formalism has to the standard transformations used in quantum mechanics. In this paper we consider a system that can be completely diagonalized by the Bogoliubov transformation. It is shown that in this case the Mandel equation can be solved and that χ−1H0= HD, where HDis the diagonalized Hamiltonian, obtained by the Bogoliubov transformation.

ISSN:0041-1450    

DOI:10.1080/00411457208232531

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A discussion based on the Boltzmann equation is given of the way in which the heat-conduction equation C(∂T/∂t) = KV2T must be modified when the temperature T changes appreciably within a mean free path. Assuming a temperature-independent relaxation time τ, a hierarchy of linear equations of increasing accuracy is obtained, of which the first member is the modification C[(∂T/∂t) + τ (∂2T/∂t2)] = = KV2T suggested earlier by many authors. Damped-wave solutions for T are shown to exist over a certain frequency range, and the corresponding dispersion relations are obtained. It is shown that if τ is temperature dependent, the above conduction equation takes the nonlinear form

ISSN:0041-1450    

DOI:10.1080/00411457208232532

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A number of fluctuation-dissipation theorems are reviewed. Their relationship, relative information content, and applicability are discussed. Detailed consideration is given to some subtle points frequently glossed over. To illustrate, some general theorems and a few pedagogical examples are treated.

ISSN:0041-1450    

DOI:10.1080/00411457208232533

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

ISSN:0041-1450    

DOI:10.1080/00411457208232534

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

ISSN:0041-1450    

DOI:10.1080/00411457208232529

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor