排序方式： 共有15条查询结果，搜索用时 45 毫秒
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Miguel Kalwa Sueli P. Quináia Adelmo L. Pletsch Yohandra R. Torres Daiane Finger 《Environmental Earth Sciences》2014,72(11):4473-4481
Itaipu Lake, which includes the Itaipu hydroelectric power plant, is one of the largest dams in the world and has a strong relationship with its surroundings. The flooded area has multiple uses such as navigation, recreation, water abstraction for industrial, urban and agricultural irrigation. The lake is located at the frontier between Brazil, Argentina and Paraguay. In this study, superficial sediments collected from nine sampling sites were analysed for grain size, organic matter and 16 priority polycyclic aromatic hydrocarbons (PAHs) using high-performance liquid chromatography (HPLC) with fluorescence detector. The total concentration of PAHs in the dry sediment ranged from 35.21 to 685.37 µg kg?1. Diagnostic ratios showed that the possible source of PAHs in the Itaipu Lake could be pyrolitic and petrogenic. The potential toxicity of sediment of PAHs varied from not detected to 127.70 µg g?1, suggesting that some adverse ecological effects would arise due to PAHs in these sediments. 相似文献
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Markus Steen Fabian Faller Eli Fyhn Ullern 《Norsk geografisk tidsskrift. Norwegian journal of geography》2019,73(1):39-52
ABSTRACTThe transition to a low-carbon economy is a major challenge confronting policymakers at all government levels. In the European Union (EU), ambitious targets for reductions in greenhouse gas emission are linked to aspirations of fostering green growth at national and regional levels. These aspirations have been manifested in a recent radical policy change through the introduction of the smart specialisation research and innovation strategy (RIS3) for national and regional development. The novelty of the RIS3 compared with previous EU innovation policy is that it aims to develop regional competitiveness based on the harnessing of regional assets rather than focusing on the provision of innovation infrastructure. In this article, the authors employ a mixed-methods research approach both to explore the nature and content of energy-related priority settings in RIS3 strategies in the EU and to address the question of regions’ abilities to foster renewable energy through their place-based strategies. The article contributes to the literature on policy strategies for realising EU energy and emissions targets and the RIS3 aim of developing competitive advantages. The main conclusions are that energy-related priority settings vary substantially within RIS3, and that regional innovation policy ambitions may be hindered by unconducive policy frameworks at national levels. 相似文献
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Mauricio da Rocha Fragoso Gabriel Vieira de Carvalho Felipe Lobo Mendes Soares Daiane Gracieli Faller Luiz Paulo de Freitas Assad Raquel Toste Lívia Maria Barbosa Sancho Elisa Nóbrega Passos Carina Stefoni Böck Bruna Reis Luiz Landau Hernan G. Arango Andrew M. Moore 《Ocean Dynamics》2016,66(3):419-434
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P.L. Bender J.E. Faller J. Levine S. Moody M.R. Pearlman B.C. Silverberg 《Tectonophysics》1979,52(1-4)
A relatively low-cost system for determining both the vertical and horizontal coordinates of several dozen points per year with an accuracy of about 2 cm appears feasible. One approach considered is to use a subnanosecond pulse length laser with a few millijoules per pulse output energy and to employ single photoelectron detection of the returned signal. The single photoelectron approach has been thoroughly tested in the Lunar Laser Ranging Experiment. With a laser average power of about 50 mW, a 30-cm diameter transmit-receive aperture, 10 arc sec pointing accuracy and a beam divergence of 20 arc sec, the expected returned signal level is about 70 pulses in a 3-min interval. If the differences between the observed ranges and those calculated from a reasonably good LAGEOS ephemeris over a 3-min interval are considered, the expected standard deviation of the mean is < 0.7 cm.The calibration procedure used in lunar ranging appears capable of reducing any bias due to the photomultiplier or timing system to 0.5 cm. The other main error source we have considered for the measured optical transit time is a possible difference in arrival time in different parts of the far field pattern because of laser mode structure. This effect needs to be checked experimentally, but we expect it to be 0.5 cm or less for a laser pulse length of about 200 psec. Based on these error estimates, simulations for one week of observations from the high-mobility station have been carried out for us at the National Geodetic Survey. When a refraction model error of 0.15% was used, the uncertainty of the high-mobility station position with respect to a reference station 500 km away was found to be 2.4 cm or less in each coordinate. After the gravity-field uncertainties have been reduced, the station location accuracy will be improved further and the limitation of measuring with respect to a regional reference station can be relaxed. 相似文献
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We are in the process of developing a small portable absolute gravimeter that employs a cam-based dropping mechanism. The resulting high data rate (100 drops in 30 s) serves to compensate for the short (2 cm) dropping distance. We hope to achieve a measurement accuracy with this instrument of ±5 μgal. 相似文献
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Giuseppe Raspa Massimiliano Moscatelli Francesco Stigliano Antonio Patera Fabrizio Marconi Daiane Folle Roberto Vallone Marco Mancini Gian Paolo Cavinato Salvatore Milli Joo Felipe Coimbra Leite Costa 《Engineering Geology》2008,101(3-4):251-268
We are presenting an attempt to evaluate the spatial variability of geotechnical parameters in the upper Pleistocene–Holocene alluvial deposits of Roma (Italy) by means of multivariate geostatistics.The upper Pleistocene–Holocene alluvial deposits of Roma are sensitive to high levels of geohazard. They occupy a sizable and significant part of the city, being the foundation for many monuments, historical neighborhoods, and archaeological areas, and the main host of the present and future subway lines. We have stored information from more than 2000 geotechnical boreholes crossing the alluvial deposits into a relational database. For the present study, only the boreholes with lithologic/textural interpretation and geotechnical information were selected. The set includes 283 boreholes and 719 samples, which have a set of geotechnical information comprising physical properties and mechanical parameters.Techniques of multivariate statistics and geostatistics were combined and compared to evaluate the estimation methods of the mechanical parameters, with special reference to the drained friction angle from direct shear test (φ′). Principal Component Analysis was applied to the dataset to highlight the relationships between the geotechnical parameters. Through cross-validation analysis, multiple linear regression, kriging, and cokriging were tested as estimators of φ′. Cross-validation demonstrates that the cokriging with granulometries as auxiliary variables is the most suitable method to estimate φ′. In addition to proving that cokriging is a good estimator of φ′, cross-validation demonstrates that input data are coherent and this allows us to use them for estimation of geotechnical parameters, although they come from different laboratories and different vintages.Nevertheless, to get the same good results of cross-validation in estimation, it is necessary for granulometries to be available at grid points. Since this information being not available at all grid points, it is expected that, in the future, textural information can be derived in an indirect way, i.e., from lithologic/textural spatial reconstructions. 相似文献
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Successful development of a few parts in 109 portable g apparatus (which corresponds to a height sensitivity of about 1 cm) would have an impact on large areas of geodynamics as well as having possible application to earthquake prediction. Furthermore, the use of such an instrument in combination with classical leveling or extraterrestrially determined height data would yield information on internal mass motions. The plans for the development of such an instrument at JILA using the method of free fall will be given. The proposed interferometric method uses one element of an optical interferometer as the dropped object. Recent work has resulted in substantial progress towards the development of a new type of long-period (T > 60 sec) suspension for isolating the reference mirror (corner cube) in the interferometer. Improvements here over the isolation methods previously available, together with state-of-the-art timing and interferometric techniques, are expected to make it possible to achieve a few parts in 109 accuracy with a field-type instrument. 相似文献