The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Samuel H Friedman - One of the best experts on this subject based on the ideXlab platform.
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xim a virtual x ray observatory investigating the x ray appearance and line Profile Function of vortex rings in galaxy clusters
Astrophysical Journal Supplement Series, 2011Co-Authors: Sebastian Heinz, M Bruggen, Samuel H FriedmanAbstract:We present virtual observations of a simulated vortex ring in a galaxy cluster (such as the Virgo Cluster, where such a ring has been observed), using the virtual X-ray observatory software XIM. We derive the expected surface brightness distributions and color maps for a vortex seen at different line-of-sight angles. We present the line Profile Function {phi}({delta}{nu}) for the velocity field of a vortex ring as derived from the observations and show that the line core has a frequency dependence of {phi} {proportional_to} ({delta}{nu}/{nu}{sub 0}){sup -2} and derive this form of the line Profile from the analytic description of the asymptotic behavior of the velocity field of a vortex ring. We discuss further examples of the application of XIM to studies of galaxy clusters and present the capabilities and methodology of the publicly available code XIM.
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XIM—a Virtual X-ray Observatory: Investigating the X-ray Appearance and Line Profile Function of Vortex Rings in Galaxy Clusters
The Astrophysical Journal Supplement Series, 2011Co-Authors: Sebastian Heinz, M Bruggen, Samuel H FriedmanAbstract:We present virtual observations of a simulated vortex ring in a galaxy cluster (such as the Virgo Cluster, where such a ring has been observed), using the virtual X-ray observatory software XIM. We derive the expected surface brightness distributions and color maps for a vortex seen at different line-of-sight angles. We present the line Profile Function {phi}({delta}{nu}) for the velocity field of a vortex ring as derived from the observations and show that the line core has a frequency dependence of {phi} {proportional_to} ({delta}{nu}/{nu}{sub 0}){sup -2} and derive this form of the line Profile from the analytic description of the asymptotic behavior of the velocity field of a vortex ring. We discuss further examples of the application of XIM to studies of galaxy clusters and present the capabilities and methodology of the publicly available code XIM.
Sebastian Heinz - One of the best experts on this subject based on the ideXlab platform.
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xim a virtual x ray observatory investigating the x ray appearance and line Profile Function of vortex rings in galaxy clusters
Astrophysical Journal Supplement Series, 2011Co-Authors: Sebastian Heinz, M Bruggen, Samuel H FriedmanAbstract:We present virtual observations of a simulated vortex ring in a galaxy cluster (such as the Virgo Cluster, where such a ring has been observed), using the virtual X-ray observatory software XIM. We derive the expected surface brightness distributions and color maps for a vortex seen at different line-of-sight angles. We present the line Profile Function {phi}({delta}{nu}) for the velocity field of a vortex ring as derived from the observations and show that the line core has a frequency dependence of {phi} {proportional_to} ({delta}{nu}/{nu}{sub 0}){sup -2} and derive this form of the line Profile from the analytic description of the asymptotic behavior of the velocity field of a vortex ring. We discuss further examples of the application of XIM to studies of galaxy clusters and present the capabilities and methodology of the publicly available code XIM.
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XIM—a Virtual X-ray Observatory: Investigating the X-ray Appearance and Line Profile Function of Vortex Rings in Galaxy Clusters
The Astrophysical Journal Supplement Series, 2011Co-Authors: Sebastian Heinz, M Bruggen, Samuel H FriedmanAbstract:We present virtual observations of a simulated vortex ring in a galaxy cluster (such as the Virgo Cluster, where such a ring has been observed), using the virtual X-ray observatory software XIM. We derive the expected surface brightness distributions and color maps for a vortex seen at different line-of-sight angles. We present the line Profile Function {phi}({delta}{nu}) for the velocity field of a vortex ring as derived from the observations and show that the line core has a frequency dependence of {phi} {proportional_to} ({delta}{nu}/{nu}{sub 0}){sup -2} and derive this form of the line Profile from the analytic description of the asymptotic behavior of the velocity field of a vortex ring. We discuss further examples of the application of XIM to studies of galaxy clusters and present the capabilities and methodology of the publicly available code XIM.
M Bruggen - One of the best experts on this subject based on the ideXlab platform.
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xim a virtual x ray observatory investigating the x ray appearance and line Profile Function of vortex rings in galaxy clusters
Astrophysical Journal Supplement Series, 2011Co-Authors: Sebastian Heinz, M Bruggen, Samuel H FriedmanAbstract:We present virtual observations of a simulated vortex ring in a galaxy cluster (such as the Virgo Cluster, where such a ring has been observed), using the virtual X-ray observatory software XIM. We derive the expected surface brightness distributions and color maps for a vortex seen at different line-of-sight angles. We present the line Profile Function {phi}({delta}{nu}) for the velocity field of a vortex ring as derived from the observations and show that the line core has a frequency dependence of {phi} {proportional_to} ({delta}{nu}/{nu}{sub 0}){sup -2} and derive this form of the line Profile from the analytic description of the asymptotic behavior of the velocity field of a vortex ring. We discuss further examples of the application of XIM to studies of galaxy clusters and present the capabilities and methodology of the publicly available code XIM.
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XIM—a Virtual X-ray Observatory: Investigating the X-ray Appearance and Line Profile Function of Vortex Rings in Galaxy Clusters
The Astrophysical Journal Supplement Series, 2011Co-Authors: Sebastian Heinz, M Bruggen, Samuel H FriedmanAbstract:We present virtual observations of a simulated vortex ring in a galaxy cluster (such as the Virgo Cluster, where such a ring has been observed), using the virtual X-ray observatory software XIM. We derive the expected surface brightness distributions and color maps for a vortex seen at different line-of-sight angles. We present the line Profile Function {phi}({delta}{nu}) for the velocity field of a vortex ring as derived from the observations and show that the line core has a frequency dependence of {phi} {proportional_to} ({delta}{nu}/{nu}{sub 0}){sup -2} and derive this form of the line Profile from the analytic description of the asymptotic behavior of the velocity field of a vortex ring. We discuss further examples of the application of XIM to studies of galaxy clusters and present the capabilities and methodology of the publicly available code XIM.
A. B. Mikhailovskii - One of the best experts on this subject based on the ideXlab platform.
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Microislands in tokamaks
Physics of Plasmas, 2004Co-Authors: A. B. Mikhailovskii, Sergey Konovalov, V. S. Tsypin, E. A. Kovalishen, M. S. Shirokov, Takahisa Ozeki, F. F. Kamenets, Tomonori TakizukaAbstract:Analytical treatment of magnetic islands with high poloidal mode numbers and widths smaller than ion Larmor radius (microislands) is presented. The Profile Functions and rotation frequencies of microislands in the scope of the standard two-fluid magnetohydrodynamics are investigated. The effects of anomalous perpendicular resistivity and anomalous perpendicular electron heat conductivity are included. It is shown that, in such a problem statement, the microislands are described in terms of two Profile Functions, one of which characterizes the electric field and perturbed plasma density (the microisland Profile Function) and second—perturbed electron temperature (the electron temperature Profile Function). Analytical expressions for these Profile Functions in the case of stationary microislands are derived. Contribution of the oscillatory parallel electric current (the polarization current) into the generalized Rutherford equation for the stationary island width is calculated. The problem of rotation frequ...
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Effects of parallel viscosity on rotation of magnetic islands in tokamaks
Physics Letters A, 2003Co-Authors: Sergey Konovalov, A. B. Mikhailovskii, V. S. Tsypin, E. A. Kovalishen, M. S. Shirokov, Takahisa Ozeki, Tomonori TakizukaAbstract:Abstract Effects of parallel viscosity on rotation of magnetic islands in tokamaks are studied. The Pfirsch–Schluter regime is considered with following generalization of the results to the plateau and banana regimes. Assuming the parallel viscosity to be prevailing over the perpendicular viscosity, the superdrift magnetic islands are studied. It is found that in this case, first, the electrostatic potential Profile Function is of the Rutherford-type and, second, in contrast to the cylindrical geometry, the island rotation frequency does not depend on the nonstationarity of the Profile Function but is determined by a volume integral from the parallel viscosity.
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Extension of drift magnetic island theory beyond the common Profile Function approximation
Physics of Plasmas, 2000Co-Authors: A. B. Mikhailovskii, Sergey Konovalov, V. S. Tsypin, Ivan Cunha Nascimento, Ricardo Magnus Osorio GalvaoAbstract:The approach of several Profile Functions for studying drift magnetic islands is developed. This approach yields more favorable predictions for the role of the polarization current than the less adequate approach of a common Profile Function adopted in preceding studies. It is shown that the polarization current is stabilizing not only for subdrift islands propagating in the ion drift direction but also for islands propagating in the electron drift direction with a sufficiently low rotation frequency.
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Regularized magnetic islands. I. Hyperviscosity and Profile Functions
Physics of Plasmas, 2000Co-Authors: A. B. Mikhailovskii, V. S. Tsypin, V. D. Pustovitov, Andrei SmolyakovAbstract:The problem of the magnetic island Profile Functions is analyzed. An idea is suggested that discontinuities of the Profile Function derivatives at the island separatrix, which appear in simplified plasma models, can be eliminated by means of more complete description, i.e., the Profile Functions can be regularized. As an example, the regularization of the electrostatic potential Profile Function is considered for the case of a slab geometry when its formation is governed by the perpendicular viscosity. It is shown that for regularization of such a Profile Function one should keep in the viscosity expression the terms with higher derivatives of the velocity, usually referred to as hyperviscosity terms. A model expression for the hyperviscosity is derived by the Grad-type method. Physically, the regularization is related to the appearance of a part of the Profile Function localized in the Larmor transition layer near the island separatrix.
Frans N Van De Vosse - One of the best experts on this subject based on the ideXlab platform.
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a wave propagation model of blood flow in large vessels using an approximate velocity Profile Function
Journal of Fluid Mechanics, 2007Co-Authors: David D Bessems, Mcm Marcel Rutten, Frans N Van De VosseAbstract:Lumped-parameter models (zero-dimensional) and wave-propagation models (one-dimensional) for pressure and flow in large vessels, as well as fully three-dimensional fluid–structure interaction models for pressure and velocity, can contribute valuably to answering physiological and patho-physiological questions that arise in the diagnostics and treatment of cardiovascular diseases. Lumped-parameter models are of importance mainly for the modelling of the complete cardiovascular system but provide little detail on local pressure and flow wave phenomena. Fully three-dimensional fluid–structure interaction models consume a large amount of computer time and must be provided with suitable boundary conditions that are often not known. One-dimensional wave-propagation models in the frequency and time domain are well suited to obtaining clinically relevant information on local pressure and flow waves travelling through the arterial system. They can also be used to provide boundary conditions for fully three-dimensional models, provided that they are defined in, or transferred to, the time domain. Most of the one-dimensional wave propagation models in the time domain described in the literature assume velocity Profiles and therefore frictional forces to be in phase with the flow, whereas from exact solutions in the frequency domain a phase difference between the flow and the wall shear stress is known to exist. In this study an approximate velocity Profile Function more suitable for one-dimensional wave propagation is introduced and evaluated. It will be shown that this Profile Function provides first-order approximations for the wall shear stress and the nonlinear term in the momentum equation, as a Function of local flow and pressure gradient in the time domain. The convective term as well as the approximate friction term are compared to their counterparts obtained from Womersley Profiles and show good agreement in the complete range of the Womersley parameter α. In the limiting cases, for Womersley parameters α → 0 and α → ∞, they completely coincide. It is shown that in one-dimensional wave propagation, the friction term based on the newly introduced approximate Profile Function is important when considering pressure and flow wave propagation in intermediate-sized vessels.
