11,123 research outputs found
GRIDSITE, FUNCTIONAL DESCRIPTION
GridSite provides grid credential, proxy certificate and delegation support for web-based application
PROXYRENEWAL, ADMINISTRATOR GUIDE
The proxy renewal daemon is responsible for keeping proxy certificates valid throughout all the lifetime of corresponding job
Logging and bookkeeping, developer's guide
Logging and Bookkeeping (LB for short) is a Grid service that keeps a short-term trace of Grid jobs as they are processed by individual Grid component
Logging and bookkeeping, Administrator's guide
Logging and Bookkeeping (LB for short) is a Grid service that keeps a short-term trace of Grid jobs as they are processed by individual Grid component
Sublimation rates of carbon monoxide and carbon dioxide from comet nuclei at large distances from the Sun
One of the more attractive among the plausible scenarios for the major emission event recently observed on Comet Halley at a heliocentric distance of 14.3 AU is activation of a source of ejecta driven by an icy substance much more volatile than water. As prerequisite for the forthcoming detailed analysis of the imaging observations of this event, a simple model is proposed that yields the sublimation rate versus time at any location on the surface of a rotating cometary nucleus for two candidate ices: carbon monoxide and carbon dioxide. The model's variable parameters are the comet's heliocentric distance r and the Sun's instantaneous zenith angle z
Randomization of particle motions and the observed morphology of cometary heads
A great diversity is known to exist in the coma morphology of comets. In particular, some comets show much structural detail in their heads (such as jets, halos, fans, plumes, streamers), while others have completely structureless comas. Obvious questions arise as to why is this so and what does the presence or absence of features tell us about the emission processes on cometary nuclei. In an effort to investigate these problems, a computer code that generates synthetic images of dust comets was modified by introducing random perturbations into motions of ejected particles. It is noted that the introduction of perturbations has made the computer generated images simulate the appearance of comets quite faithfully and that by increasing the perturbations beyond a certain limit it has been possible to erase the coma morphology diagnostic of the details of the ejection process. It is proposed that the degree of collimation of an ejecta flow from discrete active sources on the nucleus surface and possible emissions of dust coma. Molecules of comet gases that radiate in the spectral region employed (and whose velocity distribution is much more chaotic than that of dust particles) and limited atmospheric seeing likewise contribute to blurring structural detail in ground-based imaging observation of comets. The absence of discrete features in the coma does no means imply the absence of localized sources of activity on the nucleus
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