Three-dimensional zonal grids about arbitrary shapes by Poisson's equation

A method for generating 3-D finite difference grids about or within arbitrary shapes is presented. The 3-D Poisson equations are solved numerically, with values for the inhomogeneous terms found automatically by the algorithm. Those inhomogeneous terms have the effect near boundaries of reducing cell skewness and imposing arbitrary cell height. The method allows the region of interest to be divided into zones (blocks), allowing the method to be applicable to almost any physical domain. A FORTRAN program called 3DGRAPE has been written to implement the algorithm. Lastly, a method for redistributing grid points along lines normal to boundaries will be described

Static load versus settlement for geometric shapes on cohesionless soil

Static loading versus settlement for circular plate, cone, and sphere on cohesionless soil - spacecraft landing gear stud

GRAPEVINE: Grids about anything by Poisson's equation in a visually interactive networking environment

A proven 3-D multiple-block elliptic grid generator, designed to run in 'batch mode' on a supercomputer, is improved by the creation of a modern graphical user interface (GUI) running on a workstation. The two parts are connected in real time by a network. The resultant system offers a significant speedup in the process of preparing and formatting input data and the ability to watch the grid solution converge by replotting the grid at each iteration step. The result is a reduction in user time and CPU time required to generate the grid and an enhanced understanding of the elliptic solution process. This software system, called GRAPEVINE, is described, and certain observations are made concerning the creation of such software

A lattice analogy for the solution of some nonlinear stress problems

Nonlinear stress problem solution by lattice analogy techniqu

Inherently Governmental Functions and Other Work Reserved for Performance by Federal Government Employees: The Obama Administration’s Proposed Policy Letter

[Excerpt] On March 31, 2010, the Office of Federal Procurement Policy (OFPP) in the Office of Management and Budget (OMB) issued a proposed policy letter on inherently governmental functions and other “work reserved for performance by federal government employees.” While not final, the policy letter represents the Obama Administration’s proposed guidance for agencies determining (1) whether particular functions are inherently governmental and (2) when functions closely associated with the performance of inherently governmental functions and critical functions should be performed by government personnel. The proposed policy letter was, in part, issued under the authority of the Duncan Hunter National Defense Authorization Act for FY2009 (NDAA\u2709) and President Obama’s memorandum of March 4, 2009, on government contracting. Section 321 of NDAA\u2709 tasked OMB with (1) reviewing existing definitions of “inherently governmental function” to determine whether such definitions are “sufficiently focused” to ensure that only government personnel perform inherently governmental functions or “other critical functions necessary for the mission of a Federal department or agency;” (2) developing a “single consistent definition” of “inherently governmental function” that would address any deficiencies in the existing definitions, reasonably apply to all agencies, and ensure that agency personnel can identify positions that perform inherently governmental functions; (3) developing criteria for identifying critical functions” that should be performed by government personnel; and (4) developing criteria for identifying positions that government personnel should perform in order to ensure that agencies develop and maintain “sufficient organic expertise and technical capacity” to perform their missions and oversee contractors’ work. President Obama’s March 4, 2009, memorandum similarly charged OMB with clarifying when outsourcing is “appropriate.

Self-trapping at the liquid vapor critical point

Experiments suggest that localization via self-trapping plays a central role in the behavior of equilibrated low mass particles in both liquids and in supercritical fluids. In the latter case, the behavior is dominated by the liquid-vapor critical point which is difficult to probe, both experimentally and theoretically. Here, for the first time, we present the results of path-integral computations of the characteristics of a self-trapped particle at the critical point of a Lennard-Jones fluid for a positive particle-atom scattering length. We investigate the influence of the range of the particle-atom interaction on trapping properties, and the pick-off decay rate for the case where the particle is ortho-positronium.Comment: 12 pages, 3 figures, revtex4 preprin

Behavior of a sandy clay under vertical impact of geometric shapes

Sandy clay response under vertical impact of cone, plate, and plane geometric shape

Tethers in space handbook

The handbook provides a list and description of ongoing tether programs. This includes the joint U.S.-Italy demonstration project, and individual U.S. and Italian studies and demonstration programs. An overview of the current activity level and areas of emphasis in this emerging field is provided. The fundamental physical principles behind the proposed tether applications are addressed. Four basic concepts of gravity gradient, rotation, momentum exchange, and electrodynamics are discussed. Information extracted from literature, which supplements and enhances the tether applications is also presented. A bibliography is appended