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91.
We present a numerical study of the set of orbits of the planar circular restricted three body problem which undergo consecutive
close encounters with the small primary, or orbits of second species. The value of the Jacobi constant is fixed, and we restrict
the study to consecutive close encounters which occur within a maximal time interval. With these restrictions, the full set
of orbits of second species is found numerically from the intersections of the stable and unstable manifolds of the collision
singularity on the surface of section that corresponds to passage through the pericentre. A ‘skeleton’ of this set of curves
can be computed from the solutions of the two-body problem. The set of intersection points found in this limit corresponds
to the S-arcs and T-arcs of Hénon’s classification which verify the energy and time constraints, and can be used to construct
an alphabet to describe the orbits of second species. We give numerical evidence for the existence of a shift on this alphabet
that describes all the orbits with infinitely many close encounters with the small primary, and sketch a proof of the symbolic
dynamics. In particular, we find periodic orbits that combine S-type and T-type quasi-homoclinic arcs. 相似文献
92.
A.-C. da Silva C. Loisy A. Cerepi R. Toullec E. Kiefer L. Humbert P. Razin 《Sedimentary Geology》2009,219(1-4):237-251
The Paleocene of the Campo section, Spain has different sedimentological characteristics above and below the Mid-Paleocene Unconformity. Beneath the unconformity sediments are dominated by evaporitic carbonates and collapse breccias. Above it they are characterized by continental detrital beds alternating with paleosols. Different subaerial features are observed and correspond to different porosity values, pore–throat sizes and micrite morphologies. Unexposed or intertidal facies have low porosity, low throat–pore size (mesoporosity) and well preserved rhombic crystals. Intermediate exposed facies (paleosols) possess medium porosity, medium pore–throat size (microporosity) and mainly micro-rhombic crystals. Finally, the facies corresponding to high exposure intensity and to evaporitic original facies presents high porosity, permeability, large pore–throat size and rounded micritic crystals. These observations show that the emersion phase caused important dissolution, especially when associated with an easily dissolved original lithofacies. 相似文献
93.
Suzan Pantaroto de Vasconcellos Elaine Crespim Georgiana Feitosa da Cruz Diego Barbosa Senatore Karen Christina Marques Simioni Eugênio Vaz dos Santos Neto Anita Jocelyne Marsaioli Valéria Maia de Oliveira 《Organic Geochemistry》2009,40(5):574-588
The detection of microorganisms with potential for biodeterioration and biodegradation in petroleum fields is of great relevance, since these organisms may be related to a decrease in petroleum quality in the reservoirs or damage in the production facilities. In this sense, petroleum formation water and oil samples were collected from the Campos Basin, Brazil, with the aim of isolating microorganisms and evaluating their ability to degrade distinct classes of hydrocarbon biomarkers (9,10-dihydrophenanthrene, phytane, nonadecanoic acid and 5α-cholestane). Twenty eight bacterial isolates were recovered and identified by sequencing their 16S rRNA genes. Biodegradation assays revealed that bacterial metabolism of hydrocarbons occurred through reactions based on oxidation, carbon–carbon bond cleavage and generation of new bonds or by the physical incorporation of hydrocarbons into microbial cell walls. Based on the biodegradation results, selective PCR-based systems were developed for direct detection in petroleum samples of bacterial groups of interest, namely Bacillus spp., Micrococcus spp., Achromobacter xylosoxidans, Dietzia spp. and Bacillus pumilus. Primer sets targeting 16S rRNA genes were designed and their specificity was confirmed in silico (i.e. computational analysis) and in PCR reactions using DNA from reference strains as positive and negative controls. Total DNA from oil was purified and the amplification tests revealed the presence of the target bacteria in the samples, unraveling a significant potential for petroleum deterioration in the reservoirs sampled, once proper conditions are present for hydrocarbon degradation. The application of molecular methods for rapid detection of specific microorganisms in environmental samples would be valuable as a supporting tool for the evaluation of oil quality in production reservoirs. 相似文献
94.
Redivo Polyana Comino Sanches Luciana de Carvalho Alves Marcelo Barbosa da Silva Jhonatan 《Water Resources》2021,48(6):905-913
Water Resources - The Queima Pé Stream Basin (QPSB) and Ararão River Basin (ARB) in central Brazil have had recurrent problems with water scarcity. This may get worse under anthropogenic... 相似文献
95.
Guilherme Vieira da Silva João Luiz Baptista de Carvalho Antonio Henrique da Fontoura Klein 《Ocean & Coastal Management》2011,54(8):569-576
Inlet stabilization is a common practice in Brazil, as it is worldwide. In this paper we present results of the analysis of the stabilization practices of the Camacho Inlet, located in Santa Catarina State, southern Brazil. This inlet is maintained intermittently, in accordance with a regime designed to benefit both local fishermen and rice farmers. Fishermen require this inlet to be open as a navigation channel during the fishing season; rice farmers needs it closed during the irrigation period to allow the pumping of fresh water from the Congonhas River which drains into the Camacho’s backbarrier lagoon. An additional complication arises from the tendency of this inlet to close naturally due to infilling by dune migration. Aerial images spanning a 65 year time period (1938-2003) were analyzed, demonstrating the variability in the inlet’s width between 0 (closed) and 360 m. The analysis of inlet stability and user needs indicate that an appropriate solution is the implementation of an annual inlet dredging program in the austral autumn. This would allow for the inlet to remain open from May to September and then close naturally for the rest of the year, providing for a backbarrier fresh water reservoir during the irrigation period. 相似文献
96.
97.
Amaro J. Rica da Silva José P. S. Lemos 《Celestial Mechanics and Dynamical Astronomy》2008,100(3):191-208
We derive the equations for the gravity assist manoeuvre in the general 2D case without the constraints of circular planetary
orbits or widely different masses as assumed by Broucke (AIAA/AAS 1988) and obtain the slingshot conditions and maximum energy
gain for arbitrary mass ratios of two colliding rigid bodies. Using the geometric view developed in an earlier paper by the
authors (Rica da Silva, A., Lemos, J.P.S.: Am. J. Phys. 74, 584–590, 2006) the possible trajectories are computed for both attractive or repulsive interactions yielding a further insight
on the slingshot mechanics and its parametrization. . The general slingshot manoeuvre for arbitrary masses is explained as a particular case of the possible outcomes of attractive
or repulsive binary collisions, and the correlation between asymptotic information and orbital parameters is obtained in general. 相似文献
98.
Vajapeyam S. Srinivasan Hugo M. de Alcântara Carlos de O. Galvão Ulisses A. Bezerra John E. de Brito Leite Cunha 《水文研究》2021,35(5):e14194
Catchments have highly variable yields of runoff and soil erosion. The size, land use and the surface cover play a significant role and influence the catchment response and parameter values of simulation models. Two experimental basins—the Cariri basins—were equipped in a semi-arid region of Brazil, for obtaining runoff and sediment yield at different catchment scales, as well as, to evaluate the influence of the land use and surface cover. In the first basin, located in the municipality of Sumé, the field studies were carried out at two different scales: four micro-catchments with an area of around 0.5 ha and nine standard Wischmeier-type erosion plots of 100 m2. The experimental units had varied vegetation and management. They were subjected only to natural rainfall events, and were monitored from 1982 to 1991. The total runoff and total sediment yield were determined for each of the events. The installations in the second basin, in the municipality of São João do Cariri, from 1999, include two erosion plots, three micro-catchments, and two sub-catchments of a small basin. These basins are still being monitored for runoff and sediment production. Among the micro-catchments two are nested to detect any scale effect at the micro-catchment level. Nearly 600 events of precipitation, that produced runoff in at least one of the experimental units, have been registered. These data have been used to evaluate the influence of various factors, including cultivation practices and to calibrate hydrological models for plots and micro-catchments. Parameters have been tested by means of cross validations among micro-catchments and sub-catchments. The data sets are made available to all the catchment hydrology researchers and others at https://doi.org/10.5281/zenodo.4690886 . 相似文献
99.
da Silva Richarde Marques Santos Celso Augusto Guimarães Silva Jorge Flávio Casé Braga da Costa Silva Alexandro Medeiros Brasil Neto Reginaldo Moura 《Natural Hazards》2020,104(2):1953-1954
Natural Hazards - The article “Spatial distribution and estimation of rainfall trends and erosivity in the Epitácio Pessoa reservoir catchment, Paraíba, Brazil”, written by da... 相似文献
100.
Abner Carvalho‐Batista Joo Alberto Farinelli Pantaleo Antonio Leo Castilho Rogrio Caetano da Costa 《Marine Ecology》2019,40(2)
Upwelling areas are among the most productive ecosystems on the planet, influencing the biology of marine organisms. This study investigated the population dynamics of the shrimp Artemesia longinaris in two regions in southeastern Brazil, one inside (Macaé—Rio de Janeiro State) and one outside (Ubatuba—State of São Paulo) the Cabo Frio upwelling area. The aim was to verify the influence of the upwelling phenomenon on the abundance, growth, longevity, size of sexual maturity, and reproductive period of the species. In total, 188,902 individuals were captured at Macaé and 3,461 at Ubatuba. Individuals captured at Macaé showed larger maximum size, higher longevity, and slower growth rate, besides reaching sexual maturity at larger sizes than at Ubatuba. Continuous reproduction was observed in both regions, with juvenile recruitment peaks in spring and summer. Local conditions observed at Macaé were influenced by the Cabo Frio upwelling zone, characterized by productive and cooler waters that are around 20°C during most of the year. The upwelling phenomenon is probably the main factor influencing the population parameters studied here, changing the geographic patterns previously observed for the variation of these parameters in A. longinaris. 相似文献