A Heuristic Strategy to Compute Ensemble of Trajectories for 3D Low Cost Earth-Moon Transfers

The problem of finding optimal trajectories is essential for modern space mission design. When considering multibody gravitational dynamics and exploiting both low-thrust and high-thrust and alternative forms of propulsion such as solar sailing, sets of good initial guesses are fundamental for the convergence to local or global optimal solutions, using both direct or indirect methods available to solve the optimal control problem. This paper deals with obtaining preliminary trajectories that are designed to be good initial guesses as input to search optimal low-energy short-time Earth-Moon transfers with ballistic capture. A more realistic modelling is introduced, in which the restricted four-body system Sun-Earth-Moon-Spacecraft is decoupled in two patched planar Circular Restricted Three-Body Problems, taking into account the inclination of the orbital plane of the Moon with respect to the ecliptic. We present a heuristic strategy based on the hyperbolic invariant manifolds of the Lyapunov orbits around the Lagrangian points of the Earth- Moon system to obtain ballistic capture orbits around the Moon that fulfill specific mission requirements. Moreover, quasi-periodic orbits of the Sun-Earth system are exploited using a genetic algorithm to find optimal solutions with respect to total Dv, time of flight and altitude at departure. Finally, the procedure is illustrated and the full transfer trajectories assessed in view of relevant properties. The proposed methodology provides sets of low-cost and shorttime initial guesses to serve as inputs to compute fully optimized three-dimensional solutions considering different propulsion technologies, such as low, high, and hybrid thrust, and/or using more realistic models

Ovinos Santa Inês: estado de arte e perspectivas.

[Santa Inês hair sheep: state of art and perspectives]. Abstract: The Santa Inês hair sheep breed is found in whole to areas of Brazil. Its origin has been object of vary speculations. However, the most probable could be traced starting from combinations of four genetic sources: a) Criuola is wool type of sheep, brought by Portuguese and Spanish settlers, but that eliminated the wool under tropical conditions was; b) Hair sheep breeds originating from of the African continent, which originated most of the hair sheep breeds from Brazil, Central America and Caribbean; c) Bergamácia sheep breed from Italian, which was crossed with the remaining sheep of those originating from of the African continent, and Morada Nova, followed by adaptation, selection and evolution for absence of wool; d) finally, in the end of the decade of 80, a small group of the breeders added to Santa Inês the Somalis and Suffolk breeds. The breed presents good reproductive, adaptability and growth potential. The pattern of the coat calor includes the white, the red, the black and the mailed. In field conditions the ewes reach weights of 40-60 kg and the males can reach up to 120 kg. The selection practiced in the breed has been done in direction for size and body weight, absence of wool and horns and, presence of an intense pigmentation. The females present good maternal ability and they get easily to give birth vigorous lambs. The age to the puberty and first lambing, lambing interval, fertility, the prolificacy and the survival rate from weaning found in the literature, vary from: 274 to 376 days, 442 to 551 days, 227 to 307 days, 83,6 to 93%, 1,1 to 1,4 and, from 69 to 87%, respectively. The Santa Inês lamb can reach 23-32 kg at weaning and gain 166 -336 kg. At slaughter, Santa Inês Lamb, had dressing percentage of approximately 48,0 %. The animals generally demonstrate capacity to develop a strong answer immunology against the nematodes gastrontestinais, even before of the weaning. That skin presents great market value, due to the high quality pattern, resultant of its largest elasticity and excellent flexibility, and great resistance, associated to a fine texture, being rendered for use in several manufactured products. In spite of the few studies involving the face Santa Inês the breed has been demonstrating to be an excellent alternative to increase the production of meat in the main areas of the country, considering its reproductive capacity, resistance sponges it gastrontestinais, skin quality and adaptability , besides good growth rate

Chaos and Synchronized Chaos in an Earthquake Model

We show that chaos is present in the symmetric two-block Burridge-Knopoff model for earthquakes. This is in contrast with previous numerical studies, but in agreement with experimental results. In this system, we have found a rich dynamical behavior with an unusual route to chaos. In the three-block system, we see the appearance of synchronized chaos, showing that this concept can have potential applications in the field of seismology.Comment: To appear in Physical Review Letters (13 pages, 6 figures

Efeito materno sobre a curva de crescimento de ovinos Santa Inês por meio de modelos de regressão aleatória.

Utilizaram-se 17.767 registros de pesos de 4.210 cordeiros da raça Santa Inês com o objetivo de avaliar a importância da inclusão do efeito materno nos modelos de estimação de componentes de (Co) variância e parâmetros genéticos resultantes para a curva de crescimento, por meio de modelos de regressão aleatória. As regressões fixas e aleatórias foram ajustadas por meio de polinômios de Legendre de ordem três, testando-se quatro modelos que diferiram quanto à inclusão dos efeitos genético aditivo materno e ambiente permanente materno. Observou-se considerável aumento no Log L e diminuição nos critérios AIC e BIC quando se adicionou o efeito materno (genético ou ambiente permanente), evidenciando sua importância. O efeito genético materno explicou maior proporção da variância fenotípica que o ambiente permanente materno ao longo da curva de crescimento. A variância genética aditiva direta estimada foi inflacionada pelo efeito materno, quando este não foi incluído no modelo de análise, refletindo o mesmo comportamento nas herdabilidades. O efeito de ambiente permanente materno contribuiu para a variância materna, como também, inflacionou variância genética materna, quando não foi considerado no modelo. Comportamento semelhantemente foi verificado com a herdabilidade materna. As correlações entre pesos nas diferentes idades estimadas pelos quatro modelos praticamente não diferiram em função da modelagem do efeito materno. O efeito materno deve ser considerado nos estudos genéticos da curva de crescimento da população em estudo. Maternal effect or growth curve of Santa Inês sheep by random regression models. Abstract - Data set of 17.767 weight records of 4.210 Santa Inês lambs were used aiming to evaluate the importance of the inclusion of the maternal effect in the model to estimate components of (Co) variance and resulting genetic parameters for the growth curve through random regression models. The fixed and random regressions were fitted using Legendre Polynomials of order three, being fit four models that differed in relation to the inclusion of the additive genetic and permanent environmental maternal effects. Considerable increase was observed in Log L and decrease in the criteria AIC and BIC when the maternal effect was included (genetic or permanent environmental), evidencing its importance. The maternal genetic effect explained larger proportion of the phenotypic variance than the maternal permanent environmental along the growth curve. The direct additive genetic variance was inflated by maternal effect, when this last one was not considered in the analysis model, reflecting the same behavior in the heritabilities. The maternal permanent environmental effect contributed to maternal variance, as well as, it inflated maternal genetic variance, when it was not considered in the model. Similar behavior was verified with maternal heritability. The correlation estimated for the four models hardly differed in function of maternal effect. The maternal effect should be considered in the genetic studies of the growth curve of Santa Inês sheep

Consumo de nutrientes de ovinos suplementados com diferentes niveis de dejeto de suinos e feno de leucena (Leucaena leucophala (Lam.) de Wit).

Esta pesquisa foi realizada com o objetivo de avaliar racoes, utilizando capim elefante (Pennisetum purpureum Schum) como volumoso, farelo do feno de leucena e dejetos desidratados de suinos em diferentes proporcoes na terminacao de ovinos, verificando os efeitos sobre o consumo