3,842 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
Yukawa bosons in two-dimensional Harmonic confinement
The ground state property of Yukawa Bose fluid confined in a radial harmonic
trap is studied. The calculation was carried out using the density functional
theory formalism within the Kohn-Sham scheme. The excess-correlation energy for
this inhomogeneous fluid is approximated via the local density approximation. A
comparison is also made with the Gross-Piteavskii model. We found that the
system of bosons interacting in terms of Yukawa potential in a harmonic trap is
energetically favorable compared to the ones interacting via contact delta
potential.Comment: 12pages, 3 figure
Theory of ferromagnetism in (A,Mn)B semiconductors
A brief review of theory of ferromagnetism of dilute magnetic semiconductors
of the form (A,Mn)B based on the double exchange model is first given. A
systematic investigation of the phenomena extending the current theory is
outlined. We begin with an investigation of the regions of instability of the
nonmagnetic towards the ferromagnetic state of a system of Mn-atoms doped in
AB-type semiconductor. A self-consistent many-body theory of the ferromagnetic
state is then developed, going beyond the mean field approaches by including
fluctuations of the Mn-spins and the itinerant hole-gas. A functional theory
suitable for computation of system properties such as Curie temperature as a
function of hole and the Mn-concentration, spin-current, etc. is formulated.Comment: 16 page
Heat and Entropy in nonextensive thermodynamics
The concepts of quantity of heat and work are deduced in the non-extensive
statistical mechanics context, following steps in parallel to those employed in
the extensive statistical mechanics.Comment: 10 page
Probabilistic structural analysis verification studies
The basic objective of this verification effort is to apply probabilistic structural analysis methods developed and implemented in the Numerical Evaluation of Stochastic Structures Under Stress (NESSUS) code to typical space propulsion components. The chosen typical components are turbine blade, high pressure duct, Lox post, and transfer tube liners. Since analysis options of increasing levels of sophistication are implemented in NESSUS incrementally, the verification efforts are also tailored to have increasing levels of sophistication during the progression of the contract. The current released version of the code is limited to linear structural analysis
A numerical study of fluids with pressure dependent viscosity flowing through a rigid porous medium
In this paper we consider modifications to Darcy's equation wherein the drag
coefficient is a function of pressure, which is a realistic model for
technological applications like enhanced oil recovery and geological carbon
sequestration. We first outline the approximations behind Darcy's equation and
the modifications that we propose to Darcy's equation, and derive the governing
equations through a systematic approach using mixture theory. We then propose a
stabilized mixed finite element formulation for the modified Darcy's equation.
To solve the resulting nonlinear equations we present a solution procedure
based on the consistent Newton-Raphson method. We solve representative test
problems to illustrate the performance of the proposed stabilized formulation.
One of the objectives of this paper is also to show that the dependence of
viscosity on the pressure can have a significant effect both on the qualitative
and quantitative nature of the solution
Justification of Power-Law Canonical Distributions Based on Generalized Central Limit Theorem
A self-consistent thermodynamic framework is presented for power-law
canonical distributions based on the generalized central limit theorem by
extending the discussion given by Khinchin for deriving Gibbsian canonical
ensemble theory. The thermodynamic Legendre transform structure is invoked in
establishing its connection to nonextensive statistical mechanics.Comment: 8 pages. Some minor corrections are made, with no changes in the
conclusion
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