Final state predictions for J2 gravity perturbed motion of the Earth’s artificial satellites using Bispherical coordinates

AbstractIn this paper, initial value problem for dynamical astronomy will be established using Bispherical coordinates. A computational algorithm is developed for the final state predictions for J2 gravity perturbed motion of the Earth’s artificial satellites. This algorithm is important in targeting, rendezvous maneuvers as well for scientific researches. The applications of the algorithm are illustrated by numerical examples of some test orbits of different eccentricities. The numerical results are extremely accurate and efficient

Analytical formulations to the method of variation of parameters in terms of universal Y's functions

The method of variation of parameters still has a great interest and wide applications in mathematics, physics and astrodynamics. In this paper, universal functions (the Y's functions) based on Goodyear's time transformation formula were used to establish a variation of parameters method which is useful in slightly perturbed two-body initial value problem. Moreover due to its universality, the method avoids the switching among different conic orbits which are commonly occurring in space missions. The position and velocity vectors are written in terms of f and g series. The method is developed analytically and computationally. For the analytical developments, exact literal formulations for the differential system of variation of the epoch state vector are established. Symbolical series solution of the universal Kepler's equation was also established, and the literal analytical expressions of the coefficients of the series are listed in Horner form for efficient and stable evaluation. For computational developments of the method, an efficient algorithm was given using continued fraction theory. Finally, a short note on the method of solution was given just for the reader guidance

Eclipse intervals for satellites in circular orbit under the effects of Earth’s oblateness and solar radiation pressure

In this work, the circumstances of eclipse for a circular satellites’ orbit are studied. The time of passage of the ingress and egress points is calculated. Finally, the eclipse intervals of satellites’ orbit are calculated. An application was done taken into account the effects of solar radiation pressure and Earth’s oblateness on the orbital elements of circular orbit satellite

l-Methioninase from some Streptomyces isolates I: Isolation, identification of best producers and some properties of the crude enzyme produced

Among 60 isolates of Streptomyces tested; only 40 isolates were capable to utilize l-methionine as the only source of nitrogen in medium. In addition, 24 of these isolates could grow in medium amended with l-methionine as a source of nitrogen and carbon. Qualitative rapid plate assay test shows the ability of 18 of these isolates to grow with a pink color surrounding their colonial growth, while 6 of these isolates could grow and utilize l-methionine without any pink color around their colonial growth. Quantitative assay test shows the rate of l-methioninase production by all isolates tested. Permeabilization treatment including chemical and physical methods proved that l-methioninase was found to be extracellularly produced. The results also indicate that l-methioninase production was not correlated with growth rate or l-methionine consumption in medium. On the other hand, quantitative assay test shows that these six isolates were l-methioninase negative and failed to produce any amount of l-methioninase. In addition, results also show that isolates No. 4 and No. 60 were the most suitable for l-methioninase production, these two isolates were characterized and identified as Streptomyces sp. DMMMH 4 and Streptomyces sp. MDMMH 60 using 16S rRNA with accession No. in gene bank. Furthermore, optimal conditions for enzyme activity produced by the two isolates were established in relation to temperature, pH, reaction time and type of buffer used and its molarities

A Hybrid Clustering Algorithm based on Honey Bees Mating Optimization and Greedy Randomized Adaptive Search Procedure

Abstract. This paper introduces a new hybrid algorithmic nature inspired approach based on the concepts of the Honey Bees Mating Optimization Algorithm (HBMO) and of the Greedy Randomized Adaptive Search Procedure (GRASP), for optimally clustering N objects into K clusters. The proposed algorithm for the Clustering Analysis, the Hybrid HBMO-GRASP, is a two phase algorithm which combines a HBMO algorithm for the solution of the feature selection problem and a GRASP for the solution of the clustering problem. This paper shows that the Honey Bees Mating Optimization can be used in hybrid synthesis with other metaheuristics for the solution of the clustering problem with remarkable results both to quality and computational efficiency. Its performance is compared with other popular stochastic/metaheuristic methods like particle swarm optimization, ant colony optimization, genetic algorithms and tabu search based on the results taken from the application of the methodology to data taken from the UCI Machine Learning Repository

Selected research opportunities in soil physics Oportunidades selecionadas de pesquisa em física do solo

Selected research opportunities are discussed in order to guide soil science research, with emphasis on soil physics, with the aim of improving agricultural productivity and environmental quality.<br>Oportunidades selecionadas de pesquisa são discutidas para orientar a pesquisa em ciência do solo,com ênfase na física do solo, com o objetivo de melhorar a produtividade agrícola e a qualidade do ambiente