14,118 research outputs found
Density functional theory for hard-sphere mixtures: the White-Bear version Mark II
In the spirit of the White-Bear version of fundamental measure theory we
derive a new density functional for hard-sphere mixtures which is based on a
recent mixture extension of the Carnahan-Starling equation of state. In
addition to the capability to predict inhomogeneous density distributions very
accurately, like the original White-Bear version, the new functional improves
upon consistency with an exact scaled-particle theory relation in the case of
the pure fluid. We examine consistency in detail within the context of
morphological thermodynamics. Interestingly, for the pure fluid the degree of
consistency of the new version is not only higher than for the original
White-Bear version but also higher than for Rosenfeld's original fundamental
measure theory.Comment: 16 pages, 3 figures; minor changes; J. Phys.: Condens. Matter,
accepte
Time Data Sequential Processor /TDSP/
Time Data Sequential Processor /TDSP/ computer program provides preflight predictions for lunar trajectories from injection to impact, and for planetary escape trajectories for up to 100 hours from launch. One of the major options TDSP performs is the determination of tracking station view periods
Lateral vibration effects in atomic-scale friction
The influence of lateral vibrations on the stick-slip motion of a nanotip
elastically pulled on a flat crystal surface is studied by atomic force
microscopy (AFM) measurements on a NaCl(001) surface in ultra-high vacuum. The
slippage of the nanotip across the crystal lattice is anticipated at increasing
driving amplitude, similarly to what is observed in presence of normal
vibrations. This lowers the average friction force, as explained by the
Prandtl-Tomlinson model with lateral vibrations superimposed at finite
temperature. Nevertheless, the peak values of the lateral force, and the total
energy losses, are expected to increase with the excitation amplitude, which
may limit the practical relevance of this effect.Comment: To appear in Applied Physics Letter
Earth-Moon trajectories, 1965-70
Analytical model for generation of earth-moon trajectory analysis dat
Ion confinement and transport in a toroidal plasma with externally imposed radial electric fields
Strong electric fields were imposed along the minor radius of the toroidal plasma by biasing it with electrodes maintained at kilovolt potentials. Coherent, low-frequency disturbances characteristic of various magnetohydrodynamic instabilities were absent in the high-density, well-confined regime. High, direct-current radial electric fields with magnitudes up to 135 volts per centimeter penetrated inward to at least one-half the plasma radius. When the electric field pointed radially toward, the ion transport was inward against a strong local density gradient; and the plasma density and confinement time were significantly enhanced. The radial transport along the electric field appeared to be consistent with fluctuation-induced transport. With negative electrode polarity the particle confinement was consistent with a balance of two processes: a radial infusion of ions, in those sectors of the plasma not containing electrodes, that resulted from the radially inward fields; and ion losses to the electrodes, each of the which acted as a sink and drew ions out of the plasma. A simple model of particle confinement was proposed in which the particle confinement time is proportional to the plasma volume. The scaling predicted by this model was consistent with experimental measurements
A fluctuation-induced plasma transport diagnostic based upon fast-Fourier transform spectral analysis
A diagnostic, based on fast Fourier-transform spectral analysis techniques, that provides experimental insight into the relationship between the experimentally observable spectral characteristics of the fluctuations and the fluctuation-induced plasma transport is described. The model upon which the diagnostic technique is based and its experimental implementation is discussed. Some characteristic results obtained during the course of an experimental study of fluctuation-induced transport in the electric field dominated NASA Lewis bumpy torus plasma are presented
Hard-Sphere Fluids in Contact with Curved Substrates
The properties of a hard-sphere fluid in contact with hard spherical and
cylindrical walls are studied. Rosenfeld's density functional theory (DFT) is
applied to determine the density profile and surface tension for wide
ranges of radii of the curved walls and densities of the hard-sphere fluid.
Particular attention is paid to investigate the curvature dependence and the
possible existence of a contribution to that is proportional to the
logarithm of the radius of curvature. Moreover, by treating the curved wall as
a second component at infinite dilution we provide an analytical expression for
the surface tension of a hard-sphere fluid close to arbitrary hard convex
walls. The agreement between the analytical expression and DFT is good. Our
results show no signs for the existence of a logarithmic term in the curvature
dependence of .Comment: 15 pages, 6 figure
Earth-mars trajectories, 1973, volume 5, part b
Machine computations of three-dimensional ballistic interplanetary trajectories - July and August 197
Earth-mars trajectories, 1973, volume 5, part c
Machine computations of three-dimensional ballistic interplanetary trajectories - August and September 197
Earth-mars trajectories, 1971, volume 4, part b
Machine computations of three-dimensional ballistic interplanetary trajectories - April and May 197
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