59,634 research outputs found
Computer program for solving laminar, transitional, or turbulent compressible boundary-layer equations for two-dimensional and axisymmetric flow
A numerical algorithm and computer program are presented for solving the laminar, transitional, or turbulent two dimensional or axisymmetric compressible boundary-layer equations for perfect-gas flows. The governing equations are solved by an iterative three-point implicit finite-difference procedure. The software, program VGBLP, is a modification of the approach presented in NASA TR R-368 and NASA TM X-2458, respectively. The major modifications are: (1) replacement of the fourth-order Runge-Kutta integration technique with a finite-difference procedure for numerically solving the equations required to initiate the parabolic marching procedure; (2) introduction of the Blottner variable-grid scheme; (3) implementation of an iteration scheme allowing the coupled system of equations to be converged to a specified accuracy level; and (4) inclusion of an iteration scheme for variable-entropy calculations. These modifications to the approach presented in NASA TR R-368 and NASA TM X-2458 yield a software package with high computational efficiency and flexibility. Turbulence-closure options include either two-layer eddy-viscosity or mixing-length models. Eddy conductivity is modeled as a function of eddy viscosity through a static turbulent Prandtl number formulation. Several options are provided for specifying the static turbulent Prandtl number. The transitional boundary layer is treated through a streamwise intermittency function which modifies the turbulence-closure model. This model is based on the probability distribution of turbulent spots and ranges from zero to unity for laminar and turbulent flow, respectively. Several test cases are presented as guides for potential users of the software
Mesoscale assessments of cloud and rainfall over the British Isles
There are no author-identified significant results in this report
X-ray Emission from the 3C 273 Jet
We present results from four recent Chandra monitoring observations of the
jet in 3C 273 using the ACIS detector, obtained between November 2003 and July
2004. We find that the X-ray emission comes in two components: unresolved knots
that are smaller than the corresponding optically emitting knots and a broad
channel that is about the same width as the optical interknot region. We
compute the jet speed under the assumption that the X-ray emission is due to
inverse Compton scattering of the cosmic microwave background, finding that the
dimming of the jet X-ray emission to the jet termination relative to the radio
emission may be due to bulk deceleration.Comment: 2 pages, 2 figures, to appear in the proceedings of "The X-ray
Universe 2005", San Lorenzo de El Escorial (Spain), 26-30 September 200
Branching process approach for Boolean bipartite networks of metabolic reactions
The branching process (BP) approach has been successful in explaining the
avalanche dynamics in complex networks. However, its applications are mainly
focused on unipartite networks, in which all nodes are of the same type. Here,
motivated by a need to understand avalanche dynamics in metabolic networks, we
extend the BP approach to a particular bipartite network composed of Boolean
AND and OR logic gates. We reduce the bipartite network into a unipartite
network by integrating out OR gates, and obtain the effective branching ratio
for the remaining AND gates. Then the standard BP approach is applied to the
reduced network, and the avalanche size distribution is obtained. We test the
BP results with simulations on the model networks and two microbial metabolic
networks, demonstrating the usefulness of the BP approach
Tools made of ice facilitate forming of soft, sticky materials
Tools made of ice facilitate the forming or shaping of materials that are soft and sticky in the uncured state. The low-temperature of the ice slows the curing of the material, extending the working time available before setup. Handling problems are eliminated because the material does not adhere to the tool, and the melting ice serves as a lubricant
Statistical derivation of design criteria for liquid rocket combustion instability Final report
Statistical correlation between engine design and combustion stability in liquid propellant rocket engine
Application of Computable General Equilibrium Model to Derive Impacts of Surface Water Reallocation Policy
Resource /Energy Economics and Policy,
A structure in the early Universe at z 1.3 that exceeds the homogeneity scale of the R-W concordance cosmology
A Large Quasar Group (LQG) of particularly large size and high membership has been identified in the DR7QSO catalogue of the Sloan Digital Sky Survey. It has characteristic size (volume^1/3) ~ 500 Mpc (proper size, present epoch), longest dimension ~ 1240 Mpc, membership of 73 quasars, and mean redshift = 1.27. In terms of both size and membership it is the most extreme LQG found in the DR7QSO catalogue for the redshift range 1.0 = 1.28, which is itself one of the more extreme examples. Their boundaries approach to within ~ 2 deg (~ 140 Mpc projected). This new, huge LQG appears to be the largest structure currently known in the early universe. Its size suggests incompatibility with the Yadav et al. scale of homogeneity for the concordance cosmology, and thus challenges the assumption of the cosmological principle
- …