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Moore, J. E.

Publications and source records attributed to Moore, J. E..

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Placement of retroreflectors on the Lageos satellite

A model is presented for placing a large number of equal size holes in the surface of a spherical satellite. This problem differs from the classical mathematical problem of packing the maximum number of equal nonoverlapping circles on a sphere in that no hole can intersect the assembly joint at the satellite equator. The model was used during the design of Lageos to analyze the influence of the satellite diameter and hole size on the number of holes that could be placed on the satellite. The retroreflector placement pattern used in constructing Lageos was produced by the model.

Moore, J. E.↗
NASA NTRS1975

A timeline algorithm for astronomy missions

An algorithm is presented for generating viewing timelines for orbital astronomy missions of the pointing (nonsurvey/scan) type. The algorithm establishes a target sequence from a list of candidate targets in a way which maximizes total viewing time. Two special cases are treated. One concerns dim targets which, due to lighting constraints, are scheduled only during the antipolar portion of each orbit. They normally require long observation times extending over several revolutions. A minimum slew heuristic is employed to select the sequence of dim targets. The other case deals with bright, or short duration, targets, which have less restrictive lighting constraints and are scheduled during the portion of each orbit when dim targets cannot be viewed. Since this process moves much more rapidly than the dim path, an enumeration algorithm is used to select the sequence that maximizes total viewing time.

Moore, J. E.↗
NASA NTRS1975

An algorithm for a single machine scheduling problem with sequence dependent setup times and scheduling windows

An enumeration algorithm is presented for solving a scheduling problem similar to the single machine job shop problem with sequence dependent setup times. The scheduling problem differs from the job shop problem in two ways. First, its objective is to select an optimum subset of the available tasks to be performed during a fixed period of time. Secondly, each task scheduled is constrained to occur within its particular scheduling window. The algorithm is currently being used to develop typical observational timelines for a telescope that will be operated in earth orbit. Computational times associated with timeline development are presented.

Moore, J. E.↗
NASA NTRS1973

Round-off errors in cutting plane algorithms based on the revised simplex procedure

This report statistically analyzes computational round-off errors associated with the cutting plane approach to solving linear integer programming problems. Cutting plane methods require that the inverse of a sequence of matrices be computed. The problem basically reduces to one of minimizing round-off errors in the sequence of inverses. Two procedures for minimizing this problem are presented, and their influence on error accumulation is statistically analyzed. One procedure employs a very small tolerance factor to round computed values to zero. The other procedure is a numerical analysis technique for reinverting or improving the approximate inverse of a matrix. The results indicated that round-off accumulation can be effectively minimized by employing a tolerance factor which reflects the number of significant digits carried for each calculation and by applying the reinversion procedure once to each computed inverse. If 18 significant digits plus an exponent are carried for each variable during computations, then a tolerance value of 0.1 x 10 to the minus 12th power is reasonable.

Moore, J. E.↗
NASA NTRS1970

Explanation of random experiment sheduling and its application to space station analysis

The capability of the McDonnell-Douglas Phase B space station concept to complete the Blue Book Experiment program is analyzed and the Random experiment program with Resource Impact (REPRI) which was used to generate the data is described. The results indicate that station manpower and electrical power are the two resources which will constrain the amount of the Blue Book program that the station can complete. The station experiment program and its resource requirements are sensitive to levels of manpower and electrical power 13.5 men and 11 kilowatts. Continuous artificial gravity experiments have much less impact on the experiment program than experiments using separate artificial gravity periods. Station storage volume presently allocated for the FPE's and their supplies (1600 cu ft) is more than adequate. The REPRI program uses the Monte Carlo technique to generate a set of feasible experiment schedules for a space station. The schedules are statistically analyzed to determine the impact of the station experiment program resource requirements on the station concept. Also, the sensitivity of the station concept to one or more resources is assessed.

Moore, J. E.↗