Laser ranging ground station development

The employment of ground to conduct radar range measurements of the lunar distance is discussed. The advantages of additional ground stations for this purpose are analyzed. The goals which are desirable for any new type of ranging station are: (1) full time availability of the station for laser ranging, (2) optimization for signal strength, (3) automation to the greatest extent possible, (4) the capability for blind pointing, (5) reasonable initial and modest operational costs, and (6) transportability to enhance the value of the station for geophysical purposes

Density of states of a binary Lennard-Jones Glass

We calculate the density of states of a binary Lennard-Jones glass using a recently proposed Monte Carlo algorithm. Unlike traditional molecular simulation approaches, the algorithm samples distinct configurations according to self-consistent estimates of the density of states, thereby giving rise to uniform internal-energy histograms. The method is applied to simulate the equilibrium, low-temperature thermodynamic properties of a widely studied glass former consisting of a binary mixture of Lennard-Jones particles. We show how a density-of-states algorithm can be combined with particle identity swaps and configurational bias techniques to study that system. Results are presented for the energy and entropy below the mode coupling temperature.Comment: 6 pages, 3 figures, accepted by J Chem Phy

Constant Pressure Hybrid Molecular Dynamics-Monte Carlo Simulations

New hybrid Molecular Dynamics-Monte Carlo methods are proposed to increase the efficiency of constant-pressure simulations. Two variations of the isobaric Molecular Dynamics component of the algorithms are considered. In the first, we use the extended-ensemble method of Andersen [H. C. Andersen J. Chem. Phys. {\bf 72},2384 (1980)]. In the second, we arrive at a new constant-pressure Monte Carlo technique based on the reversible generalization of the weak-coupling barostat [H. J. C. Berendsen et. al J. Chem. Phys. {\bf 81}, 3684(1984)]. This latter technique turns out to be highly effective in equilibrating and maintaining a target pressure. It is superior to the extended-ensemble method, which in turn is superior to simple volume-rescaling algorithms. The efficiency of the proposed methods is demonstrated by studying two systems. The first is a simple Lennard-Jones fluid. The second is a mixture of polyethylene chains of 200 monomers.Comment: 10 pages, 4 figure

Instability of the Ekman Spiral with Applications to the Planetary Boundary Layers

Spiral boundary layer instability applied to planetary boundary layer

Density of States Monte Carlo Method for Simulation of Fluids

A Monte Carlo method based on a density-of-states sampling is proposed for study of arbitrary statistical mechanical ensembles in a continuum. A random walk in the two-dimensional space of particle number and energy is used to estimate the density of states of the system; this density of states is continuously updated as the random walk visits individual states. The validity and usefulness of the method are demonstrated by applying it to the simulation of a Lennard-Jones fluid. Results for its thermodynamic properties, including the vapor-liquid phase coexistence curve, are shown to be in good agreement with high-accuracy literature data.Comment: 5 pages, 3 figures, accepted by J Chem Phy

LANDSAT menhaden and thread herring resources investigation

The author has identified the following significant results. The most significant achievement is the successful charting of high probability fishing areas from LANDSAT MSS data

LANDSAT follow-on experiment: Gulf of Mexico menhaden and thread herring resources investigation

The author has identified the following significant results. The most significant achievement realized is the successful mapping of high probability fishing areas from LANDSAT MSS data for two Mississippi Sound missions

Laser ranging retro-reflector experiment

This report focuses on the Apollo 14 and 15 arrays, and discusses the experiments status.NAS9-11025prepared by J.E. Faller

Multicanonical Parallel Tempering

We present a novel implementation of the parallel tempering Monte Carlo method in a multicanonical ensemble. Multicanonical weights are derived by a self-consistent iterative process using a Boltzmann inversion of global energy histograms. This procedure gives rise to a much broader overlap of thermodynamic-property histograms; fewer replicas are necessary in parallel tempering simulations, and the acceptance of trial swap moves can be made arbitrarily high. We demonstrate the usefulness of the method in the context of a grand-multicanonical ensemble, where we use multicanonical simulations in energy space with the addition of an unmodified chemical potential term in particle-number space. Several possible implementations are discussed, and the best choice is presented in the context of the liquid-gas phase transition of the Lennard-Jones fluid. A substantial decrease in the necessary number of replicas can be achieved through the proposed method, thereby providing a higher efficiency and the possibility of parallelization.Comment: 8 pages, 3 figure, accepted by J Chem Phy