908,000 research outputs found
On the entropy bound of three dimensional simplicial gravity
It is proven that the partition function of 3-dimensional simplicial gravity
has an exponential upper bound with the following assumption: any three
dimensional sphere is constructed by repeated identification of
neighboring links and neighboring triangles in the boundary of a simplicial
3-ball. This assumption is weaker than the one proposed by other authors.Comment: 6 pages, two figures (in uudecode compressed tar
Microstates of Four-Dimensional Rotating Black Holes from Near-Horizon Geometry
We show that a class of four-dimensional rotating black holes allow
five-dimensional embeddings as black rotating strings. Their near-horizon
geometry factorizes locally as a product of the three-dimensional anti-deSitter
space-time and a two-dimensional sphere (AdS_3 x S^2), with angular momentum
encoded in the global space-time structure. Following the observation that the
isometries on the AdS_3 space induce a two-dimensional (super)conformal field
theory on the boundary, we reproduce the microscopic entropy with the correct
dependence on the black hole angular momentum.Comment: 11 pages, revte
Evaluation of three turbulence models for the prediction of steady and unsteady airloads
Two dimensional quasi-three dimensional Navier-Stokes solvers were used to predict the static and dynamic airload characteristics of airfoils. The following three turbulence models were used: the Baldwin-Lomax algebraic model, the Johnson-King ODE model for maximum turbulent shear stress, and a two equation k-e model with law-of-the-wall boundary conditions. It was found that in attached flow the three models have good agreement with experimental data. In unsteady separated flows, these models give only a fair correlation with experimental data
Categorification and correlation functions in conformal field theory
A modular tensor category provides the appropriate data for the construction
of a three-dimensional topological field theory. We describe the following
analogue for two-dimensional conformal field theories: a 2-category whose
objects are symmetric special Frobenius algebras in a modular tensor category
and whose morphisms are categories of bimodules. This 2-category provides
sufficient ingredients for constructing all correlation functions of a
two-dimensional rational conformal field theory. The bimodules have the
physical interpretation of chiral data, boundary conditions, and topological
defect lines of this theory.Comment: 16 pages, Invited contribution to the ICM 200
Three-dimensional boundary layer analysis program Blay and its application
The boundary layer calculation program (BLAY) is a program code which accurately analyzes the three-dimensional boundary layer of a wing with an undefined plane. In comparison with other preexisting programs, the BLAY is characterized by the following: (1) the time required for computation is shorter than any other; (2) the program is adaptable to a parallel processing computer; and (3) the program is associated with a secondary accuracy in the z-direction. As a boundary layer modification to transonic nonviscous flow analysis programs, it is used to adjust viscous and nonviscous interference problems repeatedly. Its efficiency is an important factor in cost reduction in aircraft designing
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