Laser manipulation and cooling of (anti)hydrogen

This paper is a summary of a talk presented at the Antihydrogen Workshop in Munich, July 1992. We discuss the possibilities of laser cooling antihydrogen and the compatibility of laser cooling with the experimental environment needed for the production and trapping of antihydrogen. Most envisioned experiments will require or be enhanced by the production of very cold antihydrogen.     

A parallel stochastic method for solving linearly constrained concave global minimization problems

A parallel stochastic algorithm is presented for solving the linearly constrained concave global minimization problem. The algorithm is a multistart method and makes use of a Bayesian stopping rule to identify the global minimum with high probability. Computational results are presented for more than 200 problems on a Cray X-MP EA/464 supercomputer.     

Problems of interpreting energy loss data for non-zero emergent angles

The energy-angle distribution has been measured for heavy projectiles (9 ? Z₁ ? 92) incident on thin carbon foils in the velocity region $\text{0.4 ? ν/ν}{}_0\text{? 1 (ν}{}_0\text{= e}{}^2\text{/}\text{h}\text{?}\text{)}$. Using ²⁰Ne data as an example, we report results that demonstrate that the thickness dependence of the specific energy loss depends strongly on the emergent angle of the ions. This observation resolves apparent discrepancies in the literature.     

An equivalent subproblem relaxation for improving the solution of a class of transportation scheduling problems

In this paper an algorithm is presented for determining the K best paths that may contain cycles in a directed network.The basic idea behind the algorithm is quite simple. Once the best path has been determined it is excluded from the network in such a way that no new path is formed and no more paths are excluded. This step leads to an enlarged network where all the paths, but the best one, can be determined. The method is repeated until the desired paths have been computed.The proposed algorithm can be used not only for the classical K shortest paths problem but also for ranking paths under a nonlinear objective function, provided that an algorithm to determine the best path exists.Computational results are presented and comparisons with other approaches for the classical problem are made.     

Conservation Properties of Smoothed Particle Hydrodynamics Applied to the Shallow Water Equation

Kelvin's circulation theorem and its implications for potential vorticity (PV) conservation are among the most fundamental concepts in ideal fluid dynamics. In this note, we discuss the numerical treatment of these concepts with the Smoothed Particle Hydrodynamics (SPH) and related methods. We show that SPH satisfies an exact circulation theorem in an interpolated velocity field, and that, when appropriately interpreted, this leads to statements of conservation of PV and generalized enstrophies. We also indicate some limitations where the analogy with ideal fluid dynamics breaks down.