The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Chun-gon Kim - One of the best experts on this subject based on the ideXlab platform.
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low earth Orbit Space environment simulation and its effects on graphite epoxy composites
Composite Structures, 2006Co-Authors: Joo-hyun Han, Chun-gon KimAbstract:In this study, a low Earth Orbit (LEO) Space environment simulation facility, capable of simulating major LEO Space environment constituents such as high vacuum, ultraviolet (UV) radiation, thermal cycling and atomic oxygen (AO) atmosphere, is introduced. Under the simulated LEO Space environment, graphite/epoxy composites, which are widely applied to Space structures, were tested to study the LEO Space environment effects on the composites. Tensile properties, as well as mass loss of the graphite/epoxy composites, after being exposed to AO atmosphere and the synergistic LEO Space environment, were investigated. The surface morphology of the composites under LEO Space environment effects was also observed by scanning electron microscope (SEM). Experimental results showed that LEO environment and its synergistic effects cause considerable damage to the surface of composites.
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Low earth Orbit Space environment simulation and its effects on graphite/epoxy composites
Composite Structures, 2006Co-Authors: Joo-hyun Han, Chun-gon KimAbstract:In this study, a low Earth Orbit (LEO) Space environment simulation facility, capable of simulating major LEO Space environment constituents such as high vacuum, ultraviolet (UV) radiation, thermal cycling and atomic oxygen (AO) atmosphere, is introduced. Under the simulated LEO Space environment, graphite/epoxy composites, which are widely applied to Space structures, were tested to study the LEO Space environment effects on the composites. Tensile properties, as well as mass loss of the graphite/epoxy composites, after being exposed to AO atmosphere and the synergistic LEO Space environment, were investigated. The surface morphology of the composites under LEO Space environment effects was also observed by scanning electron microscope (SEM). Experimental results showed that LEO environment and its synergistic effects cause considerable damage to the surface of composites.
Juergen Hausen - One of the best experts on this subject based on the ideXlab platform.
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Orbit Spaces of Small Tori
Results in Mathematics, 2003Co-Authors: Annette A’campo-neuen, Juergen HausenAbstract:Consider an algebraic torus of small dimension acting on an open subset of ℂn, or more generally on a quasiaffine variety such that a separated Orbit Space exists. We discuss under which conditions this Orbit Space is quasiprojective. One of our counterexamples provides a toric variety with enough effective invariant Cartier divisors that is not embeddable into a smooth toric variety.
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Orbit Spaces of small tori
arXiv: Algebraic Geometry, 2001Co-Authors: Annette A’campo-neuen, Juergen HausenAbstract:Consider an algebraic torus of small dimension acting on an open subset of a complex vector Space, or more generally on a quasiaffine variety such that a separated Orbit Space exists. We discuss under which conditions this Orbit Space is quasiprojective. One of our counterexamples provides a toric variety with enough effective invariant Cartier divisors that is not embeddable into a smooth toric variety.
James Lucietti - One of the best experts on this subject based on the ideXlab platform.
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On the uniqueness of extremal vacuum black holes
Classical and Quantum Gravity, 2010Co-Authors: Pau Figueras, James LuciettiAbstract:We prove uniqueness theorems for asymptotically flat, stationary, extremal, vacuum black hole solutions, in four and five dimensions with one and two commuting rotational Killing fields respectively. As in the non-extremal case, these problems may be cast as boundary value problems on the two dimensional Orbit Space. We show that the Orbit Space for solutions with one extremal horizon is homeomorphic to an infinite strip, where the two boundaries correspond to the rotational axes, and the two asymptotic regions correspond to spatial infinity and the near-horizon geometry. In four dimensions this allows us to establish the uniqueness of extremal Kerr amongst asymptotically flat, stationary, rotating, vacuum black holes with a single extremal horizon. In five dimensions we show that there is at most one asymptotically flat, stationary, extremal vacuum black hole with a connected horizon, two commuting rotational symmetries and given interval structure and angular momenta. We also provide necessary and sufficient conditions for four and five dimensional asymptotically flat vacuum black holes with the above symmetries to be static (valid for extremal, non-extremal and even non-connected horizons).
Joo-hyun Han - One of the best experts on this subject based on the ideXlab platform.
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low earth Orbit Space environment simulation and its effects on graphite epoxy composites
Composite Structures, 2006Co-Authors: Joo-hyun Han, Chun-gon KimAbstract:In this study, a low Earth Orbit (LEO) Space environment simulation facility, capable of simulating major LEO Space environment constituents such as high vacuum, ultraviolet (UV) radiation, thermal cycling and atomic oxygen (AO) atmosphere, is introduced. Under the simulated LEO Space environment, graphite/epoxy composites, which are widely applied to Space structures, were tested to study the LEO Space environment effects on the composites. Tensile properties, as well as mass loss of the graphite/epoxy composites, after being exposed to AO atmosphere and the synergistic LEO Space environment, were investigated. The surface morphology of the composites under LEO Space environment effects was also observed by scanning electron microscope (SEM). Experimental results showed that LEO environment and its synergistic effects cause considerable damage to the surface of composites.
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Low earth Orbit Space environment simulation and its effects on graphite/epoxy composites
Composite Structures, 2006Co-Authors: Joo-hyun Han, Chun-gon KimAbstract:In this study, a low Earth Orbit (LEO) Space environment simulation facility, capable of simulating major LEO Space environment constituents such as high vacuum, ultraviolet (UV) radiation, thermal cycling and atomic oxygen (AO) atmosphere, is introduced. Under the simulated LEO Space environment, graphite/epoxy composites, which are widely applied to Space structures, were tested to study the LEO Space environment effects on the composites. Tensile properties, as well as mass loss of the graphite/epoxy composites, after being exposed to AO atmosphere and the synergistic LEO Space environment, were investigated. The surface morphology of the composites under LEO Space environment effects was also observed by scanning electron microscope (SEM). Experimental results showed that LEO environment and its synergistic effects cause considerable damage to the surface of composites.
Hideki Ishihara - One of the best experts on this subject based on the ideXlab platform.
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Exactly solvable strings in Minkowski Spacetime
Classical and Quantum Gravity, 2010Co-Authors: Hiroshi Kozaki, Tatsuhiko Koike, Hideki IshiharaAbstract:We study the integrability of the equations of motion for the Nambu–Goto strings with a cohomogeneity-one symmetry in Minkowski Spacetime. A cohomogeneity-one string has a world surface which is tangent to a Killing vector field. By virtue of the Killing vector, the equations of motion reduce to the geodesic equation in the Orbit Space. Cohomogeneity-one strings are classified into seven classes (types I to VII). We investigate the integrability of the geodesic equations for all the classes and find that the geodesic equations are integrable. For types I to VI, the integrability comes from the existence of Killing vectors on the Orbit Space which are the projections of Killing vectors on Minkowski Spacetime. For type VII, the integrability is related to a projected Killing vector and a nontrivial Killing tensor on the Orbit Space. We also find that the geodesic equations of all types are exactly solvable, and show the solutions.
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exactly solvable strings in minkowski Spacetime
arXiv: General Relativity and Quantum Cosmology, 2009Co-Authors: Hiroshi Kozaki, Tatsuhiko Koike, Hideki IshiharaAbstract:We study the integrability of the equations of motion for the Nambu-Goto strings with a cohomogeneity-one symmetry in Minkowski Spacetime. A cohomogeneity-one string has a world surface which is tangent to a Killing vector field. By virtue of the Killing vector, the equations of motion can be reduced to the geodesic equation in the Orbit Space. Cohomogeneity-one strings are classified into seven classes (Types I to VII). We investigate the integrability of the geodesic equations for all the classes and find that the geodesic equations are integrable. For Types I to VI, the integrability comes from the existence of Killing vectors on the Orbit Space which are the projections of Killing vectors on Minkowski Spacetime. For Type VII, the integrability is related to a projected Killing vector and a nontrivial Killing tensor on the Orbit Space. We also find that the geodesic equations of all types are exactly solvable, and show the solutions.
