“96·8”华北暴雨数值模拟与稳定性分析

分析1996年8月发生在华北地区的台风暴雨过程的环流形势，发现：副热带高压与台风低压之间的气压梯度很大，宽广的偏南急流源源不断地向北输送水汽和能量，而太行山一带正处于汇合区，构成十分有利的暴雨天气形势。应用MM5数值预报方法对1996年8月4—5日的降雨天气过程进行数值模拟，并依据天气学原理和位涡理论对此过程的稳定性进行分析认为：（1）MM5数值预报模式较好地模拟出了台风暴雨的物理过程。（2）此次降雨的不稳定层结有南高北低现象，同时有对称不稳定和对流不稳定存在；条件性对称不稳定可使环流加速，对降水有一定的增幅作用。     

宁夏鸳鸯湖电厂空冷气象条件分析

通过在宁夏鸳鸯湖电厂建立气温、风向、风速60 m梯度及地面观测站,与邻近的灵武市气象站展开为期一年的同步观测,获得实地观测资料。利用两地同步气象观测资料进行对比分析,揭示出电厂所在地气候特点。同时结合灵武市气象站1971~2000年观测资料,采用相关性分析方法,订正得到电厂地面历年气象要素特征值。结果表明,电厂风向和风速特征明显有别于邻近的灵武市气象站。分析结果主要用于该地火电厂空冷系统的安装与安全运行。     

2005年11月26日九江--瑞昌5.7级地震浅析

2005年11月26日,在江西省九江县与瑞昌市交界处发生5.7级地震,震源深度10km。宏观震中在九江县港口乡。震中烈度Ⅶ度,极震区为北东向的椭圆,烈度分布受瑞昌盆地内地形地貌条件的控制;5.7级地震的最大余震为ML5.3级,序列类型为主震—余震型,余震较丰富,余震区长轴为北西向。此次地震经历了较长期的应力应变积累过程,发生在江西分宜—黄海北部北东向ML≥4.0级地震活动带和湖北西部—江西南昌ML≥3.0级地震活动带的交汇部位,与大区域地震活动性中长期异常相关。     

建筑物立面激光点云的定位

车载式近景目标3维测量系统,采用激光扫描仪获取建筑物立面点云。激光点云仅具有扫描仪坐标系下的坐标,不便于其他数据融合进行3维建模。文中根据系统的特点和要求,通过建立相应的坐标系,利用已有或优化的坐标转换模型确定坐标系之间的坐标转换关系。依据基准点与载体平台GPS接收机之间同步观测数据将激光点云在扫描仪坐标系下的坐标经过多次坐标转换,得到基准点所在当地坐标系下的坐标。使系统实现了满足精度要求的建筑物立面激光点云的定位工作。     

Sulfate Attack on Concrete in an Inland Salt Lake Environment

INTRODUCTIONSulfate attack is one of the reasons for concretestructures deteriorating earlier than usual,thusshowing poor durability.The SO42-from the sur-rounding environment such as ocean,saline,groundwater,and even the concrete itself,reacts with thehydration products of cement,whichleads to the de-terioration of the concrete(Li et al.,2000;Kang,1995;Neville,1983;Samarai,1976).The deteriora-tionincludes three processes:the external swelling,cracking,peeling,and disjointing caused by …     

First Record of Fossil Mesocupes from China （Coleoptera： Archostemata： Cupedidae）

Three new fossil species of the genus Mesocupes of fossil cupedids,M.angustilabialis sp. nov.,M.latilabialis sp.nov.and M.collaris sp.nov.,are described from the Jiulongshan Formation of Inner Mongolia,China.These new species are the first three records of fossil Mesocupes in China as well as the oldest ones in the world now.This finding also extends the geographical distribution of this genus from Central to East Asia.In addition,based on the ratio of the length of the last to the penultimate abdominal ventrites of new beetles distinctly lower than that of the species from the Karabastau Formation,the age of Daohugou fossil-bearing beds might be older than that of Karatau assemblage and consequently of Middle Jurassic.     

Geological analysis and FT dating of the large-scale right-lateral strike-slip movement of the Red River fault zone

Tectonically, the large-scale right-lateral strike-slip movement along the Red River fault zone is char-acterized at its late phase with the southeastward extension and deformation of the Northwestern Yunnan normal fault depression on its northern segment, and the dextral shear displacement on its central-southern segment. Research of the relations between stratum deformation and fault movement on the typical fault segments, such as Jianchuan, southeast Midu, Yuanjiang River, Yuanyang, etc. since the Miocene Epoch shows that there are two times dextral faulting dominated by normal shearing occurring along the Red River fault zone since the Miocene Epoch. The fission track dating (abbrevi-ated to FT dating, the same below) is conducted on apatite samples collected from the above fault segments and relating to these movements. Based on the measured single grain’s age and the con-fined track length, we choose the Laslet annealing model to retrieve the thermal history of the samples, and the results show that the fault zone experienced two times obvious shear displacement, one in 5.5 ± 1.5 MaBP and the other in 2.1± 0.8 MaBP. The central-southern segment sees two intensive uplifts of mountain mass in the Yuanjiang River-Yuanyang region at 3.6―3.8 MaBP and 1.6―2.3 MaBP, which correspond to the above-mentioned two dextral normal displacement events since the late Miocene Epoch.     

1954年山丹7.3级地震灾害

1954年2月11日,中国西部河西走廊发生山丹7.3级强烈地震,这是建国以来发生在西北地区的第一个大地震。地震造成47人死亡,332人受伤,数万人无家可归;房屋损坏7277间,估计财产损失远高于2003年山丹6.1级地震灾害的直接经济损失。极震区烈度达Ⅺ度,红寺湖盆地、山丹县城破坏最重,山丹地区受灾面积4800km2。本文简要介绍了山丹地震参数、地震烈度及震区环境;重点描述了房屋建筑物破坏,分析了地震灾害特点及其经济损失估计。最后探讨了这次地震震害的成因、防震减灾的经验及其借鉴意义。     

Collision leading to multiple-stage large-scale extrusion in the Qinling orogen: Insights from the Mianlue suture

The geologic framework of the Phanerozoic Qinling–Dabie orogen was built up through two major suturing events of three blocks. From north to south these include the North China craton (including the north Qinling block), the Qinling–Dabie microblock, and the South China craton (including the Bikou block), separated by the Shangdan and Mianlue sutures. The Mianlue suture zone contains evidence for Mesozoic extrusion tectonics in the form of major strike–slip border faults surrounding basement blocks, a Late Paleozoic ophiolite and a ca. 240–200 Ma thrust belt that reformed by 200–150 Ma thrusts during A-type (intracontinental) subduction. The regional map pattern shows that the blocks are surrounded by complexly deformed Devonian to Early Triassic metasandstones and metapelites, forming a regional-scale block-in-matrix mélange fabric. Five distinct tectonic units have been recognized in the belt: (1) basement blocks including two types of Precambrian basement, crystalline and transitional; (2) continental margin slices including Early Paleozoic strata, and Late Paleozoic fluviodeltaic sedimentary rocks, proximal and distal fan clastics, reflecting the development of a north-facing rift margin on the edge of the South China plate; (3) out of sequence oceanic crustal slices including strongly deformed postrift, deep-water sedimentary rocks, sheeted dikes, basalts, and mafic–ultramafic cumulates of a Late Paleozoic ophiolite suite, developing independent of the rift margin in a separate basin; (4) out-of-sequence island-arc slices; (5) accretionary wedge slices. All the tectonic units were deformed during three geometrically distinct deformation episodes (D₁, D₂ and D₃ during 240–200 Ma). Units 2–4 involved southward thrusting and vertical then southward extrusion of about 20 km of horizontal displacement above the autochthonous basement during the D₁ episode. Thrust slices 20 km south of the Mianlue suture are related to this vertical extrusion due to the same rock assemblages, ages and kinematics. The D₂ and D₃ episodes folded all the units in a thick-skinned style about east–west (D₂) and west–northwest (D₃) axes in the Mianlue suture zone. An early foreland propagating sequence of accretion of Late Paleozoic rocks deposited above the Yangtze craton is not involved in D₁ deformation but is temporally equivalent to the D₂ and D₃ deformation in the Mianlue suture. Two stages of strike–slip faulting mainly occurred at the end of D₂ and D₃, respectively. During D₂ deformation, the Bikou block was obliquely indented to the ESE into the Mianlue suture, rather than being thrust over the Mianlue suture from the north as a part of the Qinling–Dabie microblock. During D₃ deformation, however, the Bikou block was bounded by the south boundary fault of the Mianlue suture, and the Yangpingguan fault on the south. These faults are coeval strike–slip faults, but of opposite senses, and accommodated minor southwestward extrusion of the Bikou block into Songpan–Ganze orogen. The other basement blocks north of the Mianlue suture were extruded eastward by about 20 km of lateral displacement, based on the offset of the Wudang dome, during the D₃ episode due to the northeastward indentation of the Hannan complex of the South China craton. Post-D₃ emplacement of granite, cutting across the strike–slip faults such as the Mianlue suture, provides a minimum age of 200 Ma for D₃ deformation. Therefore, based on insights from the evolution of the Mianlue suture, the D₂ and D₃ episodes in the Mianlue suture and its neighbors are not responsible for and associated with the two-stage extrusion of the Dabie UHP-HP terranes from the Foping dome to the present erosional surface (more than 350 km).     

Dynamic analysis of eco-environmental changes based on remote sensing and geographic information system: an example in Longdong region of the Chinese Loess Plateau

The Chinese Loess Plateau is suffering from severe soil erosion. The eco-environmental changes of the plateau are believed to have an important influence on global eco-environmental sustainability; hence, this problem has attracted considerable attention from scientists around the world. This study has two purposes; application of remote sensing (RS) and geographic information system (GIS) techniques in the dynamic analysis of eco-environmental changes in the semiarid zone; and using the Longdong region of the Chinese Loess Plateau as an example, to make dynamic analysis of the eco-environmental changes of the region during the 1986–2004 period and identify controlling factors. Landsat Thematic Mapper (TM) data at a spatial resolution of 30 m were used for analysis. Two training areas were selected in Jingning and Qingcheng counties for analysis using 10-m resolution SPOT and Landsat TM data. The satellite RS images were obtained from the Institute of Remote Sensing Application (IRSA), Chinese Academy of Sciences (CAS). Each images was rectified by Albers Equal Area Conic projection based on 1:50,000 scale topographic maps after spectrum preparation of the images. To make the precision within 1 or 2 pixels, the accurate coordinative control points of the two systems were identified. Then the interpretation key was established based on the land use/cover survey in the study area. The images were classified into six primary environmental types (farmland, forest, grassland, water, construction area, and desert) and 25 sub-types using a visual image interactive interpretation method to obtain vector and attribute data. The resultant accuracy of the land use/cover classification reached 95%. Finally, the transformation areas and ratios of various eco-environmental types in the region were calculated to obtain the transition matrixes of eco-environmental types in the two training areas, Jingning and Qingcheng. This study demonstrates that satellite RS and GIS techniques are effective tools to monitor and analyze the eco-environmental changes in the semiarid region. Visual image interactive interpretation based on GIS technique provides comprehensive information on the direction, rate, and location of eco-environmental changes. The transition matrix model can be used to precisely analyze the variation and rates of the eco-environmental types and their spatial distribution. Great land use changes have taken place Longdong during the 1986–2004 period. These eco-environmental changes were driven by natural and human factors. Natural factors influencing the Longdong region of the Chinese Loess Plateau mainly include temperature, water condition, terrain, soil, and erosion; while human activities include over-cultivation, overgrazing, and fuelwood cutting. As viewed from the extent and severity of the influences, human activities play a very important role in altering the eco-environment of the semiarid region. The study results indicate a need for future research and observation in the semiarid region.