265 research outputs found

    Uncertainty of flow in porous media

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    The problem posed to the Study Group was, in essence, how to estimate the probability distribution of f(x) from the probability distribution of x. Here x is a large vector and f is a complicated function which can be expensive to evaluate. For Schlumberger's applications f is a computer simulator of a hydrocarbon reservoir, and x is a description of the geology of the reservoir, which is uncertain

    Applying Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) spectral indices for geological mapping and mineral identification on the Tibetan Plateau

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    The Tibetan Plateau holds clues to understanding the dynamics and mechanisms associated with continental growth. Part of the region is characterized by zones of ophiolitic melange believed to represent the remnants of ancient oceanic crust and underlying upper mantle emplaced during oceanic closures. However, due to the remoteness of the region and the inhospitable terrain many areas have not received detailed investigation. Increased spatial and spectral resolution of satellite sensors have made it possible to map in greater detail the mineralogy and lithology than in the past. Recent work by Yoshiki Ninomiya of the Geological Survey of Japan has pioneered the use of several spectral indices for the mapping of quartzose, carbonate, and silicate rocks using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) thermal infrared (TIR) data. In this study, ASTER TIR indices have been applied to a region in western-central Tibet for the purposes of assessing their effectiveness for differentiating ophiolites and other lithologies. The results agree well with existing geological maps and other published data. The study area was chosen due to its diverse range of rock types, including an ophiolitic melange, associated with the Bangong-Nujiang suture (BNS) that crops out on the northern shores of Lagkor Tso and Dong Tso ("Tso" is Tibetan for lake). The techniques highlighted in this paper could be applied to other geographical regions where similar geological questions need to be resolved. The results of this study aim to show the utility of ASTER TIR imagery for geological mapping in semi-arid and sparsely vegetated areas on the Tibetan Plateau.Comment: 6 pages, 4 figures, 2 tables, Published in the International Archives of the Photogrammetry, Remote Sensing, and Spatial Information Science, Volume XXXVIII, pp. 464-469. For associated web page, see http://www.isprs.org/proceedings/XXXVIII/part8/headline/PS-1%20Interactive%20PresentationWG%20VIII5.htm

    Devonian (Frasnian) radiolarians from the Gogo Formation, Canning Basin, Western Australia

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    The Common Assessment Framework (CAF) and the evaluation of Quality in a Public Service: Case Study of Academic Services of the University of Évora, Portugal

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    Society is more and more demanding on professional terms. Therefore, in order to achieve Excellence we need to go though processes of continuous improvement and we need to measure and to evaluate Quality which is increasingly seen as a competitive and distinguishing factor between institutions. And institutions from Public Sector like Universities are no exception. It’s urgent to evaluate their quality. But a question remains: how do we evaluate them? Why is it important? Should we evaluate the graduate and post-graduate degrees, the services that support all the University,
What? In Portugal it is compulsory to evaluate the quality of the degrees taught on a Higher Education Institution. For that purpose a set of legislation has been approved: Law n.Âș38/94 of 21st November, Decree-law n.Âș205/98 of 11th July and Law n.Âș1/2003 of 6th January. But if this is a compulsory procedure, shouldn’t the structures that support all the life of a Higher Education Institution also be evaluated? What happens if, for instance, the Academic Services don’t work properly or collapse? This service is considered as essential and fundamental on Higher Education Institutions

    Palaeomagnetic re-investigation of early permian rift basalts from the Baoshan block, SW China: Constraints on the site-of-origin of the gondwana-derived eastern cimmerian terranes

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    A palaeomagnetic investigation was carried out on a series of rift basalts (Woniusi Formation) that accumulated on the Baoshan block (SW China) in the Early Permian, the aim being to provide quantitative palaeogeographical information on the eastern Cimmerian terrane as it detached from eastern Gondwana. Reliable data were obtained from four locations/28 individual cooling units, and when combined with the findings of an earlier study (three locations/19 sites) indicate that breakup occurred at 41.9°S (with errors, 34.2-51.2°S). Using this information, we fit Baoshan against Gondwana within a narrow longitudinal belt close to where northeast Greater India and northwest Australia were once in close proximity. Furthermore, we suggest that Sibumasu (Simao-Burma-Malyasia-Sumatra; the largest of the eastern Cimmerian blocks) lay directly to the east, offshore of Australia; Qiangtang and Lhasa almost certainly sat to the west (off northern Greater India-SE Arabia), but we are uncertain as to their exact configuration. Our findings are compared with several rather different models that have been published in recent years. The new palaeomagnetic constraint highlights the flexibility authors currently have in reconstructing the region, principally because of the overall lack of similar high-quality data from the various blocks. We explain how new data could resolve these ambiguities, thereby offering more robust explanations for eastern Gondwana's late Palaeozoic development

    Detrital heavy minerals constraints on the Triassic tectonic evolution of the West Qinling terrane, NW China: implications for understanding subduction of the Paleotethyan Ocean

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    We have examined the Triassic sediments in the west Qinling terrane, northeastern Tibet. These sediments consist mainly of flysch and shallow-sea and fluvial deposits with abundant lithic and heavy mineral detritus, sandwiched between and overlying Late Paleozoic and Early-Middle Triassic ophiolitic mélanges. Volcanic and metamorphic detritus dominates the lithic component of Lower Triassic sandstones accompanied by high Cr-spinel, pyroxene, and magnetite contents, indicating a mixed ophiolite and metamorphic source. Detrital mineral geochemistry further suggests that ophiolitic, high-grade metamorphic, basic, and intermediate-acidic igneous rocks must have been exposed and deeply eroded in their source area. Abundances of zircon, rutile, garnet, tourmaline, and epidote are greater in the Middle Triassic samples, and granitic and volcanic sources are the major contributors of detrital clasts. Considering these new observations on sedimentary petrography and detrital heavy mineral geochemistry, along with published data on paleocurrents, detrital zircon U-Pb ages, sedimentary facies, and regional magmatism, we suggest that these Triassic sediments represent the sedimentary fill of a forearc basin that overlies a late Paleozoic ophiolitic complex. A south-facing Andean-type convergent continental margin system developed along the southern margin of the North China block during the Triassic, in response to northward subduction of the Paleotethyan Ocean

    Tectonic History and Coalbed Gas Genesis

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    LED excitation of an on-chip imaging flow cytometer for bead-based immunoassay

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    A green LED is demonstrated to generate a uniform square illumination pattern for an on-chip imaging flow cytometer system. The proposed system is used to perform the detection of a bead-based immunoassay for a sepsis biomarker, procalcitonin

    A single Dras‐Kohistan‐Ladakh arc revealed by volcaniclastic records

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    Tectonic interpretations of arc remnants in the Himalayan orogen remain uncertain, despite their important implications for the overall convergence history between India and Eurasia. Provenance results from deep‐water volcaniclastic rocks of the Indus Suture Zone in Ladakh provide new constraints on the Mesozoic tectonic evolution of the Dras and Kohistan‐Ladakh arcs. Detrital zircon (DZ) U‐Pb ages and whole‐rock geochemistry of the fault‐bounded Upper Cretaceous Nindam and Paleocene Jurutze formations present age patterns and compositions that are consistent with those of the Dras and Kohistan‐Ladakh arcs, respectively. The combination of DZs of the Nindam and Jurutze formations with the igneous zircons of the Dras and Kohistan‐Ladakh arcs shows similar age distributions that support a Late Jurassic to Paleocene tectonic connection between all these units. We argue that the secular trends in geochemical composition of DZs and volcaniclastic material are consistent with the magmatic evolution of one convergent margin, which shifted from a primitive to a mature stage during the Late Cretaceous. The recognition of a single Dras‐Kohistan‐Ladakh arc sets the stage for reevaluating competing scenarios of the Mesozoic evolution of the India–Eurasia convergent system. We find that the most likely scenario is that of a Jurassic arc formed above a south‐dipping intraoceanic subduction zone and accreted to Eurasia during the Early Cretaceous, after which it evolved above a north‐dipping subduction zone
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