3,203 research outputs found
Development of three dimensional constitutive theories based on lower dimensional experimental data
Most three dimensional constitutive relations that have been developed to
describe the behavior of bodies are correlated against one dimensional and two
dimensional experiments. What is usually lost sight of is the fact that
infinity of such three dimensional models may be able to explain these
experiments that are lower dimensional. Recently, the notion of maximization of
the rate of entropy production has been used to obtain constitutive relations
based on the choice of the stored energy and rate of entropy production, etc.
In this paper we show different choices for the manner in which the body stores
energy and dissipates energy and satisfies the requirement of maximization of
the rate of entropy production that leads to many three dimensional models. All
of these models, in one dimension, reduce to the model proposed by Burgers to
describe the viscoelastic behavior of bodies.Comment: 23 pages, 6 figure
A thermodynamic framework to develop rate-type models for fluids without instantaneous elasticity
In this paper, we apply the thermodynamic framework recently put into place
by Rajagopal and co-workers, to develop rate-type models for viscoelastic
fluids which do not possess instantaneous elasticity. To illustrate the
capabilities of such models we make a specific choice for the specific
Helmholtz potential and the rate of dissipation and consider the creep and
stress relaxation response associated with the model. Given specific forms for
the Helmholtz potential and the rate of dissipation, the rate of dissipation is
maximized with the constraint that the difference between the stress power and
the rate of change of Helmholtz potential is equal to the rate of dissipation
and any other constraint that may be applicable such as incompressibility. We
show that the model that is developed exhibits fluid-like characteristics and
is incapable of instantaneous elastic response. It also includes Maxwell-like
and Kelvin-Voigt-like viscoelastic materials (when certain material moduli take
special values).Comment: 18 pages, 5 figure
Classical Statistics Inherent in a Quantum Density Matrix
A density matrix formulation of classical bipartite correlations is
constructed. This leads to an understanding of the appearance of classical
statistical correlations intertwined with the quantum correlations as well as a
physical underpinning of these correlations. As a byproduct of this analysis, a
physical basis of the classical statistical correlations leading to additive
entropy in a bipartite system discussed recently by Tsallis et al emerges as
inherent classical spin fluctuations. It is found that in this example, the
quantum correlations shrink the region of additivity in phase space.Comment: 10 pages, 3 figure
Simplified proofs of "Some Tauberian theorems" of Jakimovski
This article does not have an abstract
Broken-symmetry-adapted Green function theory of condensed matter systems:towards a vector spin-density-functional theory
The group theory framework developed by Fukutome for a systematic analysis of
the various broken symmetry types of Hartree-Fock solutions exhibiting spin
structures is here extended to the general many body context using spinor-Green
function formalism for describing magnetic systems. Consequences of this theory
are discussed for examining the magnetism of itinerant electrons in nanometric
systems of current interest as well as bulk systems where a vector spin-density
form is required, by specializing our work to spin-density-functional
formalism. We also formulate the linear response theory for such a system and
compare and contrast them with the recent results obtained for localized
electron systems. The various phenomenological treatments of itinerant magnetic
systems are here unified in this group-theoretical description.Comment: 17 page
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