Publications

Grey logic is not another name for fuzzy logic. Grey logic--also called grey analysis or grey system theory--is a new technology, a group of techniques for system analysis and modeling. Like fuzzy logic, grey logic is useful in situations with incomplete and uncertain information. Grey analysis is particularly applicable in instances with very limited data and in cases with little system knowledge or understanding. In this paper, a summary of the basic concepts of grey analysis is provided, with descriptions of its application to several classes of problems. Calculations methods are provided for grey relation analysis, and for modeling and prediction using grey methods.

A computer code is described which is designed to determine the fraction of time during which a given ground location is observable from one or more members of a satellite constellation in earth orbit. Ground visibility parameters are determined from the orientation and strength of an appropriate ionized cylinder (used to simulate a beam experiment) at the selected location. Satellite orbits are computed in a simplified two-body approximation computation. A variety of printed and graphical outputs is provided. 9 refs., 50 figs., 2 tabs.

An algorithm and a computer program are described for use in determining the geographic locations common between the orbit paths of two satellites or between different portions of a single satellite's orbital path. The method selected uses semi-inertial geometric constructions to determine the crossing locations. 6 refs.