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2010年5—6月南方持续性暴雨的成因分析 总被引：11，自引：8，他引：3
2010年5月5日至6月27日我国江南至华南地区出现11次持续性暴雨过程,引起华南和江南洪涝灾害。利用NCEP日再分析资料,初步分析了持续性暴雨的成因。结果表明,2010年5—6月11次持续降水期间乌拉尔山阻塞高压和贝加尔湖大槽较常年偏强且稳定维持,副热带高压异常偏强,位置稳定偏南,为华南持续暴雨天气建立了有利的稳定大尺度环流背景;强盛的季风气流不断地将暖湿水汽输送至江南至华南地区并在那里和来自中高纬度的干冷空气汇合;高原上多低值系统东传是暴雨发生发展过程中重要的中尺度对流系统。中纬度相当位温锋面南侧不稳定大气层结属性气流造成强烈的上升运动,并与强烈的水汽通量辐合为持续性致洪暴雨提供了非常有利的动力热力条件。 相似文献
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The Optimal Cross-section Design of the “Trapezoid-V” Shaped Drainage Canal of Viscous Debris Flow 总被引：1，自引：0，他引：1
Debris flow drainage canal is one of the most widely used engineering measures to prevent and manage debris flow hazards.The shape and the sizes of the cross-section are important parameters when design debris flow drainage canal.Therefore,how to design the appropriate shape and sizes of the cross-section so that the drainage canal can have the optimal drainage capacity is very important and few researched at home and abroad.This study was conducted to analyze the hydraulic condition of a Trapezoid-V shaped drainage canal and optimize its cross-section.By assuming characteristic sizes of the cross-section,the paper deduced the configuration parameter of the cross-section of a Trapezoid-V shaped debris flow drainage canal.By theory analysis,it indicates that the optimal configuration parameter is only related to the side slope coefficient and the bottom transverse slope coefficient.For this study,the Heishui Gully,a first-order tributary of the lower Jinsha River,was used as an example to design the optimal cross-section of the drainage canal of debris flow. 相似文献
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本文通过对鄂尔多斯盆地镇原地区下白垩统砂岩进行主量元素、微量元素及稀土元素REE等地球化学分析, 就下白垩统砂岩的沉积再循坏特征、化学风化及其构造背景和物质来源等展开讨论。研究表明: ① 下白垩统洛河组、环河组和罗汉洞组的物源主体上具有相似性, 且在构造背景、物源区及物源特征上有良好的继承性。物源区总体具有富石英、富方解石胶结物、钾长石或富钾矿物较斜长石多的特点, 罗汉洞组较环河组和洛河组硅质更高、方解石胶结物更少、质更纯。稀土元素REE配分模式曲线一致, 轻重稀土分馏明显, 富集大离子亲石元素Ba、Pb、Sr和轻稀土元素, 亏损高场强元素Nb、Ta、Th、Y等,自下而上随着地层变新, 沉积岩中总的稀土含量有变小的趋势, 重稀土元素分馏程度减小; ② 研究区下白垩统砂岩原始物质主要为长英质与基性岩混合岩 (如中酸性侵入岩、长英质变质岩)及部分沉积岩。研究区大部分沉积物是鄂尔多斯盆地西南缘逆冲推覆带母岩风化剥蚀的产物搬运至此沉积形成, 系首次沉积的物质, 少数沉积物 (即风成砂)为就地再次搬运堆积形成, 系再循环沉积物质; ③ 在构造背景上具有以被动大陆边缘构造环境占主要优势的特点。碎屑物主要来源于陆块源区, 其次来源于再旋回造山带和混合源区。 相似文献
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Current Knowledge of Mesozoic Coleoptera from Daohugou and Liaoning (Northeast China) 总被引：4，自引：1，他引：3
Alexander G. KIREJTSHUK Alexander G. PONOMARENKO Alexander A. PROKIN CHANG Huali Georgy V. NIKOLAJEV and REN Dong 《《地质学报》英文版》2010,84(4):783-792
<正>The present paper is devoted to an overview on fossil Coleoptera studied from Inner Mongolia, Daohugou(Middle Jurassic,Jiulongshan Formation)and Liaoning(Upper Jurassic-Lower Cretaceous,Yixian Formation)deposited in Chinese collections.As a result,species of the tribe Sperchopsini and Hydrophilini from Hydrophilidae,families and subfamilies Silphidae,Syndesinae from Lucanidae,Pleocomidae,Trogidae, Trogissitidae,Pyrochroidae,Diaperinae from Tenebrionidae,and Cerambycidae were first registered in the Mesozoic and some families were defined as new.It was shown that many superfamilies represented in the Recent Fauna were formed within the Middle Jurassic and Lower Cretaceous.The materials examined confirm the hypothesis that Cucujiformian beetles are a younger group than other infraordera of Polyphaga(Staphyliniformia and Elateriformia)and,therefore,they appeared in the fossil record only in the late Mesozoic.It was shown and confirmed that most superfamilies appeared in the fossil records before Cucujoidea.The synonymy of Notocupes Ponomarenko,1964;Sinocupes Lin,1976,syn.nov.;Amblomma Tan,Ren et Liu 2005,syn.nov.;Euryomma Tan, Ren et Shih,2006,syn.nov.,non Stein,1899 and Ovatocupes Tan et Ren,2006,syn.nov.;synonymy of Tetraphalerus Waterhouse,1901 and Odontomma Tan,Ren et Ge 2006,syn.nov.;and synonymy of Priacmopsis Ponomarenko,1966 and Latocupes Tan et Ren,2006,syn.nov.are proposed.Sinorhombocoleus papposus Tan et Ren,2009 is transferred from the family Rhombocoleidae to Schizophoridae.Cervicatinius complanus Tan,Ren et Shih,2007 and Forticatinius elegans Tan,Ren et Shih,2007 are transferred from the family Catiniidae(suborder Archostemata)to superfamily Cleroidea(suborder Polyphaga:first among the family Peltidae and second as a closely related group to the latter family).The family Parandrexidae is transferred from the superfamily Cucujoidea to Cleroidea.The ecological circumstances of the past ecosystems and hypotheses of historical development of the order Coleoptera are discussed.The age of faunas examined is considered.The list of the taxa described from Daohugou and Liaoning is compiled. 相似文献
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Two new species of elaterids assigned to two new genera with intriguing fossa on prosternum are described and illustrated： Bilineariselaterfoveatus gen. et sp. nov. and Curtelater wui gen. et sp. nov. from the Upper Jurassic-Lower Cretaceous Yixian Formation of western Liaoning, China. The origin of the clicking mechanism in these beetles and the systematic position of the two genera are briefly discussed. 相似文献
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广汉机场秋季降水低云预报 总被引：1，自引：0，他引：1
用编码法作降水低云预报。降水低云对飞机着陆影响很大,严重危及飞行安全。本文利用８０年至８９年９月、１０月８５０ｈＰａ、７００ｈＰａ、５００ｈＰａ空中资料和本站的气象资料,根据多年预报经验,筛选出六个相关关系较好的因子,进行有序排列,利用六因子二八进位制关系进行编码预报降水低云。 相似文献
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基于滑面正应力修正的边坡安全系数显示解法,研究滑面初始正应力分布对边坡稳定性的影响。假设滑面的初始正应力分布,用含有待定参数的修正函数对其进行修正,使滑体满足所有方向的力和力矩平衡条件,推导出满足所有平衡条件的安全系数方程,得到边坡安全系数值,对边坡稳定性进行评判分析。结果表明,对于三维对称边坡,不同初始滑面正应力分布对边坡稳定性影响较小,安全系数最大差别控制在5%以内;对于一般三维形状边坡,不同初始正应力分布对边坡稳定性影响较大,三维安全系数的差别在6.2%,与其他方法的差别最大达到28.7%,需要进一步验证滑面正应力分布的合理性才能应用于工程实践。 相似文献