265 research outputs found
Uncertainty of flow in porous media
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
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
The Common Assessment Framework (CAF) and the evaluation of Quality in a Public Service: Case Study of Academic Services of the University of Ăvora, Portugal
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. Itâs 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,âŠWhat?
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, shouldnât the structures that
support all the life of a Higher Education
Institution also be evaluated? What happens
if, for instance, the Academic Services
donât 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
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
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
Comment on âTransâHudson Orogen of North America and HimalayaâKarakoramâTibetan Orogen of Asia: Structural and thermal characteristics of the lower and upper platesâ by MR StâOnge et al.
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LED excitation of an on-chip imaging flow cytometer for bead-based immunoassay
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 DrasâKohistanâLadakh arc revealed by volcaniclastic records
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 deepâwater volcaniclastic rocks of the Indus Suture Zone in Ladakh provide new constraints on the Mesozoic tectonic evolution of the Dras and KohistanâLadakh arcs. Detrital zircon (DZ) UâPb ages and wholeârock geochemistry of the faultâbounded Upper Cretaceous Nindam and Paleocene Jurutze formations present age patterns and compositions that are consistent with those of the Dras and KohistanâLadakh arcs, respectively. The combination of DZs of the Nindam and Jurutze formations with the igneous zircons of the Dras and KohistanâLadakh 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 DrasâKohistanâLadakh arc sets the stage for reevaluating competing scenarios of the Mesozoic evolution of the IndiaâEurasia convergent system. We find that the most likely scenario is that of a Jurassic arc formed above a southâdipping intraoceanic subduction zone and accreted to Eurasia during the Early Cretaceous, after which it evolved above a northâdipping subduction zone
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