The Experts below are selected from a list of 44232 Experts worldwide ranked by ideXlab platform
Ryan White - One of the best experts on this subject based on the ideXlab platform.
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normal mode based analysis of electron plasma waves with second order hermitian formalism
Physics of Plasmas, 2018Co-Authors: J J Ramos, Ryan WhiteAbstract:The classic problem of the dynamic evolution and Landau damping of linear Langmuir electron waves in a collisionless plasma with Maxwellian background is cast as a second-order, self-adjoint problem with a continuum spectrum of real and positive squared frequencies. The corresponding complete basis of singular normal modes is obtained, along with their orthogonality relation. This yields easily the general expression of the time-reversal-Invariant Solution for any initial-value problem. Examples are given for specific initial conditions that illustrate different behaviors of the Landau-damped macroscopic moments of the perturbations.
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normal mode based analysis of electron plasma waves with second order hermitian formalism
arXiv: Plasma Physics, 2017Co-Authors: J J Ramos, Ryan WhiteAbstract:The classic problem of the dynamic evolution of Langmuir electron waves in a collisionless plasma and their Landau damping is cast as a second-order, self-adjoint problem with a continuum spectrum of real and positive squared frequencies. The corresponding complete basis of singular normal modes is obtained, along with their orthogonality relation. This yields easily the general expression of the time-reversal-Invariant Solution for any initial-value problem. An example is given for a specific initial condition that illustrates the Landau damping of the macroscopic moments of the perturbation.
Richard Kerner - One of the best experts on this subject based on the ideXlab platform.
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time reparametrization invariance and hamilton jacobi approach to the cosmological σ model
Protein Science, 2014Co-Authors: J W Van Holten, Richard KernerAbstract:The construction of physical models with local time-reparametrization invariance is reviewed. Negative-energy contributions to the hamiltonian are shown to be crucial for the realization of this reparametrization symmetry. The covariant formulation of the dynamics is used to develop a time and gauge Invariant Hamilton-Jacobi theory. This formalism is applied to solve for the cosmology of a homogeneous universe of the Friedmann-Lemaitre-Robertson-Walker type. After a discussion of empty universes, the FLRW theory is extended with homogeneous scalar elds generically described by a -model on some scalar manifold. An explicit gauge-Invariant Solution is constructed for the non-linear O(N)-models.
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time reparametrization invariance and hamilton jacobi approach to the cosmological sigma model
arXiv: High Energy Physics - Theory, 2013Co-Authors: J W Van Holten, Richard KernerAbstract:The construction of physical models with local time-reparametrization invariance is reviewed. Negative-energy contributions to the hamiltonian are shown to be crucial for the realization of this reparametrization symmetry. The covariant formulation of the dynamics is used to develop a time and gauge Invariant Hamilton-Jacobi theory. This formalism is applied to solve for the cosmology of a homogeneous universe of the Friedmann-Lemaitre-Robertson-Walker type. After a discussion of empty universes, the FLRW theory is extended with homogeneous scalar fields generically described by a $\sg$-model on some scalar manifold. An explicit gauge-Invariant Solution is constructed for the non-linear O(N)-models.
Igor I Klebanov - One of the best experts on this subject based on the ideXlab platform.
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model of the newtonian cosmology symmetries Invariant and partially Invariant Solutions
Communications in Nonlinear Science and Numerical Simulation, 2016Co-Authors: Igor I Klebanov, O Startsun, Sergey IvanovAbstract:Abstract Symmetry group of the equation system of ideal nonrelativistic self-gravitating fluid with zero pressure is calculated. Submodel Invariant under the subgroup of rotations SO(3) is built and symmetry group of the factorsystem is calculated. A particular analytical Invariant Solution of the factorsystem is obtained.
J J Ramos - One of the best experts on this subject based on the ideXlab platform.
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normal mode based analysis of electron plasma waves with second order hermitian formalism
Physics of Plasmas, 2018Co-Authors: J J Ramos, Ryan WhiteAbstract:The classic problem of the dynamic evolution and Landau damping of linear Langmuir electron waves in a collisionless plasma with Maxwellian background is cast as a second-order, self-adjoint problem with a continuum spectrum of real and positive squared frequencies. The corresponding complete basis of singular normal modes is obtained, along with their orthogonality relation. This yields easily the general expression of the time-reversal-Invariant Solution for any initial-value problem. Examples are given for specific initial conditions that illustrate different behaviors of the Landau-damped macroscopic moments of the perturbations.
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normal mode based analysis of electron plasma waves with second order hermitian formalism
arXiv: Plasma Physics, 2017Co-Authors: J J Ramos, Ryan WhiteAbstract:The classic problem of the dynamic evolution of Langmuir electron waves in a collisionless plasma and their Landau damping is cast as a second-order, self-adjoint problem with a continuum spectrum of real and positive squared frequencies. The corresponding complete basis of singular normal modes is obtained, along with their orthogonality relation. This yields easily the general expression of the time-reversal-Invariant Solution for any initial-value problem. An example is given for a specific initial condition that illustrates the Landau damping of the macroscopic moments of the perturbation.
F M Mahomed - One of the best experts on this subject based on the ideXlab platform.
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non linear diffusion of an axisymmetric thin liquid drop group Invariant Solution and conservation law
International Journal of Non-linear Mechanics, 2001Co-Authors: E Momoniat, D P Mason, F M MahomedAbstract:The non-linear diffusion equation describing the axisymmetric spreading of a thin incompressible liquid drop under gravity on a horizontal plane is considered. A group-Invariant Solution is derived by finding a linear combination of the three Lie point symmetries admitted by the non-linear diffusion equation which conserves the total volume of the liquid drop and which satisfies the boundary condition of vanishing thickness at the rim. It is shown that conservation of the total volume of the liquid drop and the existence of a certain conservation law for the differential equation impose the same condition on the constants in the linear combination of the three Lie point symmetries.
