Results 221 to 230 of about 47,542 (262)

The use of the variational principle in molecular perturbation theory

Journal of Chemical Physics, 1985
We have shown how the Variational Principle can be used to optimize the choice of the expansion functional and the reference state potential in molecular perturbation theory. The method was applied to a Stockmayer and to a Lennard-Jones diatomic fluid.
Saul Goldman, Bijoy Kumar
exaly   +2 more sources

Application of the variational principle to perturbation theory

American Journal of Physics, 1994
In this note I discuss briefly a rather unusual example of the use of the variational principle, which perhaps is interesting for someone who studies or teaches quantum mechanics.
exaly   +2 more sources

Separation principle of delay perturbed singular systems

IMA Journal of Mathematical Control and Information, 2023
Abstract In this paper, we establish a separation principle for a class of time-varying delay perturbed singular systems. Furthermore, we propose a singular observer to estimate the system states. Based on the Lyapunov–Krasovskii functionals, the practical stability of the proposed singular observer is achieved. These results are applied
Khawla Ben Mrad, Ines Ellouze
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P1: Principles of Perturbations

2021
There are several important mathematical preliminaries which are needed in perturbation methods and solution of differential equations. Gauge functions, order symbols, perturbation coefficient and splitting differential equations into linear and nonlinear terms, principle of perturbation solution, and review of weighted residual methods will be covered
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The hierarchical principle in perturbation theory

Il Nuovo Cimento A Series 10, 1966
The hierarchical principle is discussed in perturbation theory in the light of the fact that Cutkosky integrals can have lower-order singularities corresponding to contracting out complete closed loops. It is shown that a strict hierarchical principle can be defined for Feynman integrals in theα-representation but that due to a hitherto overlooked ...
P. V. Landshoff, D. I. Olive, J. C. Polkinghorne   +2 more
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Soliton Perturbations: A Variational Principle for the Soliton Parameters

Physica Scripta, 1979
A variational perturbation method is developed to study the evolution of a single soliton in the presence of small perturbations. Adiabatic evolution equations for the parameters of the soliton are derived to first order in the perturbation without employing methods or results from the inverse scattering theory. The analysis accounts for the effects of
Bondeson, A., Lisak, M., Anderson, D.
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Averaging Principle for Stochastic Perturbations of Multifrequency Systems

Stochastics and Dynamics, 2003
We consider the averaging principle for deterministic and stochastic perturbations of multidimensional dynamical systems for which coordinates can be introduced in such a way that the "fast" coordinates change in a torus (for Hamiltonian systems, "action-angle coordinates"). Stochastic perturbations of the white-noise type are considered.
Freidlin, M. I., Wentzell, A. D.
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Energy principle for resistive perturbations in Tokamaks

Plasma Physics, 1977
An energy principle has been found for all resistive perturbations of a circular plasma cylinder in the Tokamak scaling (kr approximately=Btheta /Bz approximately= epsilon ). It allows stability to be determined independently of the resistive scaling because resistivity is taken to be finite. The inclusion of FLR effects and viscosity would only reduce
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Versions of Ekeland’s variational principle involving set perturbations

Journal of Global Optimization, 2012
zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Phan Quoc Khanh, Dinh Ngoc Quy
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Principles of finite-dimensional perturbation theory

Low Temperature Physics, 1997
The theory of finite-dimensional perturbations of self-adjoint operators, which is aimed at the solution of physical problems, is reviewed. Special attention is paid to the special kind of operators, which permits efficient application of the J-matrix technique. The spectral density of a periodic J-matrix is calculated.
I. V. Krasovskiı̆, V. I. Peresada
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