Shape-changing solar sails for novel mission applications

In order to increase the range of potential mission applications of solar sail technology, this paper introduces the concepts of shape change and continuously variable optical properties to large gossamer spacecraft. Merging the two concepts leads to the idea of solar sails as multi-functional platforms that can have potential benefits over conventional solar sails by delivering additional key mission functions such as power collection, sensing and communications. To this aim, the paper investigates the static deflection of a thin inelastic circular sail film with a variable surface reflectivity distribution. The sail film is modelled as a single surface framed by a rigid supporting hoop structure. When changing the reflectivity coefficient across the sail surface, the forces acting on the sail can be controlled without changing the incidence angle relative to the Sun. In addition, by assigning an appropriate reflectivity function across the sail, the load distribution due to solar radiation pressure can also be manipulated to control the billowing of the film. By an appropriate choice of reflectivity across the sail, specific geometries can be generated, such as a parabolic reflector, thus enabling a multi-functional sail. This novel concept of optical reconfiguration can potentially extend solar sail mission applications

Sedimentation of the Lower Cretaceous Xiagou formation and Its Response to Regional Tectonics in the Qingxi Sag, Jiuquan Basin, NW China

Under the constraint of an isochronous sequence stratigraphic framework, sediment infill of the Xiagou Formation reflects the overall control of dynamic tectonic movements and episodic sedimentations in the Qingxi Sag. Structure reactivity during post-depositional processes could cause stratigraphic variations in longitudinal time and lateral space. This study documents sediment infill features and their response to the tectonic evolutions of the Qingxi Sag. The data sets include comparison of cores, well drilling, 3D seismic, inter-well correlation, wave impedance inversion profiles, original strata recovery data, sedimentary fades spatial evolution and their superimposition with paleogeomorphology. The Jiuquan Basin is a Mesozoic-Cenozoic superposition basin comprising an early rifting graben phase and a later compression phase. Since the Early Cretaceous, the basin has undergone four major tectonic episodes: 1) extension during the Early Cretaceous, 2) tectonic inversion caused by northwest-southeast contraction from the Late Cretaceous to the Paleocene, 3) weak extension from the Eocene to the Miocene and 4) contraction from the Miocene to the present. Therefore, the Jiuquan Basin is the product of taphrogenic, collisional and shearing movements. Seismic interpretations of sequence and maximum flooding surface divide the Xiagou Formation into three third order sequences: SQK1g(0), SQK1g(1) and SQK1g(2+3). Five sedimentary facies associations are identified: the shoreland plain, fan delta dominated sedimentary systems, turbidite deposits, shallow lakes and half-deep lake systems. From K1g(0) to K1g(2+3), decreased sandstone percentages in three fan delta areas indicate a continuously transgressive process, which shows the transition from proximal to distal sites in most statistic wells and an obvious decrease of fan delta scales. The northeast-southwest faults control the lakeward distributions of delta fronts and turbidite fans. The correspondence of sedimentary infill and its response to tectonic movements have been demonstrated in the Qingxi Sag. The more active eastern part of the northeastern boundary fault has an important influence on the northeastward migration of depocenters in the Xiagou Formation. The topography developed continuously from K1g(0) to K1g(2+3), but the diminished subsidence indicates the dominant geological process varying from intense fault rifting in an early period to relatively gentle and overall subsidence in a later period during the Early Cretaceous. (C) 2013 Elsevier Ltd. All rights reserved.Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education TPR-2011-09Project of "Double strong effect, driving mechanism and hydrocarbon significance of tectonic activity during depositional period of Dongying Formation in Qikou and Nanpu Sag, Eastern China" 41272122Geological Science

The first hirnantian (Uppermost Ordovician) Odontopleurid trilobite from western Gondwana (Argentina)

An odontopleurid trilobite remain is described for the fi rst time from Hirnantian (uppermost Ordovician) rocks of Western Gondwana. Very rare material, represented by a single left librigena, comes from a new fossil locality of the Don Braulio Formation in the Eastern Argentine Precordillera. Based on an updated systematic discussion, the fossil is tentatively referred to Eoleonaspis Sheng. Environmental and paleogeographical settings of this fi nding suggest that the genus would be eurytopic, having a cosmopolitan geographical distribution during the Ordovician-Silurian interval. In addition, the new evidence reinforces that scarce odontopleurids, often represented by Eoleonaspis, characterize a trilobite association together with Mucronaspis Destombes, strengthening it as a worldwide Hirnantian biostratigraphic indicator.É descrito pela primeira vez resto de trilobita odontopleurídeo de rochas do Gondwana Ocidental (Hirnantiano, porção mais superior do Ordoviciano). O material é muito raro, representado por uma única librigena esquerda proveniente de uma nova localidade da Formação Don Braulio na Precordilheira Oriental Argentina. Com base em uma discussão sistemática atualizada, o fóssil é tentativamente referido como Eoleonaspis Sheng. Confi gurações ambientais e paleogeográfi cas deste achado sugerem que o gênero seria euritópico, tendo uma distribuição geográfi ca cosmopolita durante o intervalo Ordoviciano-Siluriano. Além disso, a nova evidência reforça que odontopleurídeos escassos, muitas vezes representados por Eoleonaspis, caracterizam uma associação trilobita juntamente com Mucronaspis Destombes, fortalecendo-o como um indicador bioestratigráfi co mundial do Hirnantiano.Fil: Halpern, Karen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Rustán, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Meroi Arcerito, Facundo René. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentin

BESII Detector Simulation

A Monte Carlo program based on Geant3 has been developed for BESII detector simulation. The organization of the program is outlined, and the digitization procedure for simulating the response of various sub-detectors is described. Comparisons with data show that the performance of the program is generally satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM

Phasor Estimation for Grid Power Monitoring: Least Square vs. Linear Kalman Filter

International audienc

The only known cyclopygid–‘atheloptic’ trilobite fauna from North America: the upper Ordovician fauna of the Pyle Mountain Argillite and its palaeoenvironmental significance

The trilobite fauna of the upper Ordovician (middle Katian) Pyle Mountain Argillite comprises a mixture of abundant mesopelagic cyclopygids and other pelagic taxa and a benthic fauna dominated by trilobites lacking eyes. Such faunas were widespread in deep water environments around Gondwana and terranes derived from that continent throughout Ordovician time but this is the only known record of such a fauna from North America and thus from Laurentia. It probably reflects a major sea level rise (the ‘Linearis drowning events’) as does the development of coeval cyclopygid-dominated deep water trilobite faunas in terranes that were marginal to Laurentia and are now preserved in Ireland and Scotland. The Pyle Mountain Argillite trilobite fauna occurs with a deep water Foliomena brachiopod fauna and comprises 22 species. Pelagic trilobites (mostly cyclopygids) constitute 36% of the preserved sclerites, and 45% of the fauna is the remains of trilobites lacking eyes, including one new species, Dindymene whittingtoni sp. nov. Three species of cyclopygid are present, belonging in Cyclopyge, Symphysops and Microparia (Heterocyclopyge). Cyclopygids are widely thought to have been stratified in the water column in life and thus their taxonomic diversity reflects the relative depths of the sea-beds on which their remains accumulated. A tabulation of middle and upper Katian cyclopygid-bearing faunas from several palaeoplates and terranes arranged on the basis of increasing numbers of cyclopygid genera allows an assessment of the relative depth ranges of the associated benthic taxa. The Pyle Mountain Argillite fauna lies towards the deeper end of this depth spectrum