The Experts below are selected from a list of 252231 Experts worldwide ranked by ideXlab platform
M Csanad - One of the best experts on this subject based on the ideXlab platform.
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new family of Simple Solutions of relativistic perfect fluid hydrodynamics
Physics Letters B, 2008Co-Authors: T Csorgő, M I Nagy, M CsanadAbstract:Abstract A new class of accelerating, exact and explicit Solutions of relativistic hydrodynamics is found—more than 50 years after the previous similar result, the Landau–Khalatnikov solution. Surprisingly, the new Solutions have a Simple form, that generalizes the renowned, but accelerationless, Hwa–Bjorken solution. These new Solutions take into account the work done by the fluid elements on each other, and work not only in one temporal and one spatial dimensions, but also in arbitrary number of spatial dimensions. They are applied here for an advanced estimation of initial energy density and life-time of the reaction in ultra-relativistic heavy ion collisions. New formulas are also conjectured, that yield further important increase of the initial energy density estimate and the measured life-time of the reaction if the value of the speed of sound is in the realistic range.
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detailed description of accelerating Simple Solutions of relativistic perfect fluid hydrodynamics
Physical Review C, 2008Co-Authors: M I Nagy, T Csorgő, M CsanadAbstract:In this paper we describe in full details a new family of recently found exact Solutions of relativistic, perfect fluid dynamics. With an ansatz that generalizes the well-known Hwa-Bjorken solution we obtain a wide class of new exact, explicit, and Simple Solutions, which have a remarkable advantage as compared to presently known exact and explicit Solutions: they do not lack acceleration. They can be utilized for the description of the evolution of the matter created in high energy heavy ion collisions. Because these Solutions are accelerating, they provide a more realistic picture than the well-known Hwa-Bjorken solution, and give more insight into the dynamics of the matter. We exploit this by giving an advanced Simple estimation of the initial energy density of the produced matter in high energy collisions, which takes acceleration effects, i.e., the work done by the pressure, and the modified change of the volume elements, into account. We also give an advanced estimation of the life-time of the reaction. Our new Solutions can also be used to test numerical hydrodynamical codes reliably. In the end, we also give an exact, 1+1 dimensional, relativistic hydrodynamical solution, where the initial pressure and velocity profile is arbitrary, and we showmore » that this general solution is stable for perturbations.« less
T Csorgő - One of the best experts on this subject based on the ideXlab platform.
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new family of Simple Solutions of relativistic perfect fluid hydrodynamics
Physics Letters B, 2008Co-Authors: T Csorgő, M I Nagy, M CsanadAbstract:Abstract A new class of accelerating, exact and explicit Solutions of relativistic hydrodynamics is found—more than 50 years after the previous similar result, the Landau–Khalatnikov solution. Surprisingly, the new Solutions have a Simple form, that generalizes the renowned, but accelerationless, Hwa–Bjorken solution. These new Solutions take into account the work done by the fluid elements on each other, and work not only in one temporal and one spatial dimensions, but also in arbitrary number of spatial dimensions. They are applied here for an advanced estimation of initial energy density and life-time of the reaction in ultra-relativistic heavy ion collisions. New formulas are also conjectured, that yield further important increase of the initial energy density estimate and the measured life-time of the reaction if the value of the speed of sound is in the realistic range.
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detailed description of accelerating Simple Solutions of relativistic perfect fluid hydrodynamics
Physical Review C, 2008Co-Authors: M I Nagy, T Csorgő, M CsanadAbstract:In this paper we describe in full details a new family of recently found exact Solutions of relativistic, perfect fluid dynamics. With an ansatz that generalizes the well-known Hwa-Bjorken solution we obtain a wide class of new exact, explicit, and Simple Solutions, which have a remarkable advantage as compared to presently known exact and explicit Solutions: they do not lack acceleration. They can be utilized for the description of the evolution of the matter created in high energy heavy ion collisions. Because these Solutions are accelerating, they provide a more realistic picture than the well-known Hwa-Bjorken solution, and give more insight into the dynamics of the matter. We exploit this by giving an advanced Simple estimation of the initial energy density of the produced matter in high energy collisions, which takes acceleration effects, i.e., the work done by the pressure, and the modified change of the volume elements, into account. We also give an advanced estimation of the life-time of the reaction. Our new Solutions can also be used to test numerical hydrodynamical codes reliably. In the end, we also give an exact, 1+1 dimensional, relativistic hydrodynamical solution, where the initial pressure and velocity profile is arbitrary, and we showmore » that this general solution is stable for perturbations.« less
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Simple Solutions of relativistic hydrodynamics for systems with ellipsoidal symmetry
Acta Physica Hungarica A) Heavy Ion Physics, 2004Co-Authors: T Csorgő, L P Csernai, Yogiro Hama, T KodamaAbstract:Simple, self-similar, analytic Solutions of (1+3)-dimensional relativistic hydrodynamics are presented for ellipsoidally symmetric finite fireballs corresponding to non-central collisions of heavy ions at relativistic bombarding energies. The hydrodynamical Solutions are obtained for a new, general family of equations of state with the possibility of describing phase transitions.
Piotr T Chruściel - One of the best experts on this subject based on the ideXlab platform.
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asymptotically Simple Solutions of the vacuum einstein equations in even dimensions
Communications in Mathematical Physics, 2005Co-Authors: Michael T Anderson, Piotr T ChruścielAbstract:We show that a set of conformally invariant equations derived from the Fefferman-Graham tensor can be used to construct global Solutions of vacuum Einstein equations, in all even dimensions. This gives, in particular, a new, Simple proof of Friedrich's result on the future hyperboloidal stability of Minkowski space-time, and extends its validity to even dimensions.
M I Nagy - One of the best experts on this subject based on the ideXlab platform.
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new family of Simple Solutions of relativistic perfect fluid hydrodynamics
Physics Letters B, 2008Co-Authors: T Csorgő, M I Nagy, M CsanadAbstract:Abstract A new class of accelerating, exact and explicit Solutions of relativistic hydrodynamics is found—more than 50 years after the previous similar result, the Landau–Khalatnikov solution. Surprisingly, the new Solutions have a Simple form, that generalizes the renowned, but accelerationless, Hwa–Bjorken solution. These new Solutions take into account the work done by the fluid elements on each other, and work not only in one temporal and one spatial dimensions, but also in arbitrary number of spatial dimensions. They are applied here for an advanced estimation of initial energy density and life-time of the reaction in ultra-relativistic heavy ion collisions. New formulas are also conjectured, that yield further important increase of the initial energy density estimate and the measured life-time of the reaction if the value of the speed of sound is in the realistic range.
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detailed description of accelerating Simple Solutions of relativistic perfect fluid hydrodynamics
Physical Review C, 2008Co-Authors: M I Nagy, T Csorgő, M CsanadAbstract:In this paper we describe in full details a new family of recently found exact Solutions of relativistic, perfect fluid dynamics. With an ansatz that generalizes the well-known Hwa-Bjorken solution we obtain a wide class of new exact, explicit, and Simple Solutions, which have a remarkable advantage as compared to presently known exact and explicit Solutions: they do not lack acceleration. They can be utilized for the description of the evolution of the matter created in high energy heavy ion collisions. Because these Solutions are accelerating, they provide a more realistic picture than the well-known Hwa-Bjorken solution, and give more insight into the dynamics of the matter. We exploit this by giving an advanced Simple estimation of the initial energy density of the produced matter in high energy collisions, which takes acceleration effects, i.e., the work done by the pressure, and the modified change of the volume elements, into account. We also give an advanced estimation of the life-time of the reaction. Our new Solutions can also be used to test numerical hydrodynamical codes reliably. In the end, we also give an exact, 1+1 dimensional, relativistic hydrodynamical solution, where the initial pressure and velocity profile is arbitrary, and we showmore » that this general solution is stable for perturbations.« less
Jeffrey M Wooldridge - One of the best experts on this subject based on the ideXlab platform.
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Simple Solutions to the initial conditions problem in dynamic nonlinear panel data models with unobserved heterogeneity
2002Co-Authors: Jeffrey M WooldridgeAbstract:I study a Simple, widely applicable approach to handling the initial conditions problem in dynamic, nonlinear unobserved effects models. Rather than attempting to obtain the joint distribution of all outcomes of the endogenous variables, I propose finding the distribution conditional on the initial value (and the observed history of strictly exogenous explanatory variables). The approach is flexible, and results in Simple estimation strategies for at least three leading dynamic, nonlinear models: probit, Tobit, and Poisson regression. I treat the general problem of estimating average partial effects, and show that Simple estimators exist for important special cases.
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Simple Solutions to the initial conditions problem in dynamic nonlinear panel data models with unobserved heterogeneity
Journal of Applied Econometrics, 2002Co-Authors: Jeffrey M WooldridgeAbstract:I study a Simple, widely applicable approach to handling the initial conditions problem in dynamic, nonlinear unobserved effects models. Rather than attempting to obtain the joint distribution of all outcomes of the endogenous variables, I propose finding the distribution conditional on the initial value (and the observed history of strictly exogenous explanatory variables). The approach is flexible, and results in Simple estimation strategies for at least three leading dynamic, nonlinear models: probit, Tobit and Poisson regression. I treat the general problem of estimating average partial effects, and show that Simple estimators exist for important special cases. Copyright © 2005 John Wiley & Sons, Ltd.
