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Journal of Geographical Sciences - The spatial relationships between traffic accessibility and supply and demand (S&D) of ecosystem services (ESs) are essential for the formulation of... 相似文献
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We study a model of particle acceleration coupled with an MHD model of magnetic reconnection in unstable twisted coronal loops. The kink instability leads to the formation of helical currents with strong parallel electric fields resulting in electron acceleration. The motion of electrons in the electric and magnetic fields of the reconnecting loop is investigated using a test-particle approach taking into account collisional scattering. We discuss the effects of Coulomb collisions and magnetic convergence near loop footpoints on the spatial distribution and energy spectra of high-energy electron populations and possible implications on the hard X-ray emission in solar flares. 相似文献
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BIAN Jin-hu LI Ai-nong JIN Hua-an LEI Guang-bin HUANG Cheng-quan LI Meng-xue 《山地科学学报》2013,10(5):754-767
How to deal with geometric distortion is an open problem when using the massive amount of satellite images at a national or global scale,especially for multi-temporal image analysis.In this paper,an algorithm is proposed to automatically rectify the geometric distortion of time-series CCD multispectral data of small constellation for environmental and disaster mitigation(HJ-1A/B) which was launched by China in 2008.In this algorithm,the area-based matching method was used to automatically search tie points firstly,and then the polynomial function was introduced to correct the systematic errors caused by the satellite motion along the roll,pitch and yaw direction.The improved orthorectification method was finally used to correct pixel displacement caused by off-nadir viewing of topography,which are random errors in the images and cannot be corrected by the polynomial equation.Nine scenes of level 2 HJ CCD images from one path/row were taken as the warp images to test the algorithm.The test result showed that the overall accuracy of the proposed algorithm was within 2 pixels(the average residuals were 37.8 m,and standard deviations were 19.8 m).The accuracies of 45.96% validation points(VPs) were within 1 pixel and 90.33% VPs were within 2 pixels.The discussion showed that three main factors including the distortion patterns of HJ CCD images,percent of cloud cover and the varying altitude of the satellite orbit may affect the search of tie points and the accuracy of results.Although the influence of varying altitude of the satellite orbits is less than the other factors,it is noted that detailed satellite altitude information should be given in the future to get a more precise result.The proposed algorithm should be an efficient tool for the geo-correction of HJ CCD multi-spectral images. 相似文献
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全国异常高温酷热 淮河出现暴雨洪涝—2000年7月— 总被引:1,自引:0,他引:1
7月份 ,东北地区东部、华北中南部、淮河、汉水流域及西南地区大部、华南东部的降水量接近常年或偏多 ,黄淮的一些地区发生不同程度的暴雨洪涝灾害 ;全国其余大部地区降水显著偏少 ,气温偏高 ,京、津、晋、内蒙古、辽、甘、青及新疆大部出现持续高温酷热天气。本月共有 4个热带风暴生成 ,其中一强热带风暴在我国登陆。1 天气概况 7月 ,主要雨带位于东北东部、河北南部、黄淮中西部、汉水流域、西南大部以及华南东部等地 ,东北地区东部、华北平原中南部、汉水流域、西南地区大部、华南大部月降水量一般有 1 0 0~ 30 0 mm,部分地区达 30… 相似文献
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The Bogda Shan orogenic belt is interpreted to be an Upper Palaeozoic continental rift, which was closed towards the end of the Carboniferous period. Intrusive activities in that belt are represented mainly by a large number of diabasic sills, dykes and stocks with sparse dioritic and granitic bodies. Determinations on a group of samples from the Shangdaheyan intrusion yielded a mineral-rock Rb-Sr isochron with an age of 298.4±0.76 Ma and an initial87Sr/86Sr ratio of 0.7041. In combination with field evidence, these results indicate that most of the intusions of the Bogda Shan orogenic belt were emplaced during the Hercynian cycle as a result of initial extension following rift closure, and that post-Hercynian intrusive activities are not important in that belt. 相似文献
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Brine shrimp (Artemia parthenogenetica) which had ingested three water-insoluble antibacterial drugs i.e. sulfadiazine(SD), oxytetracycline (OTC) and erythromycin
estolate (ERY-Es) were fed toTilapia and Mysis IIIof Penaeus orientalis K. The drug contents in the predators were then determined. After administration of drugs toTilapia and Mysis III, through the bio-encapsulation of the brine shrimp, efficacious therapeutical concentration of OTC and ERY-Es
(but not SD) in the predators could be reached and maintained for more than 8 hours. 相似文献