基于GIS的云南省海子沟流域泥石流危险性评价

在分析研究泥石流灾害特征的基础上,指出海子沟泥石流的爆发主要受到松散堆积物、坡度、降水、地质、植被等因素影响.据此,建立起泥石流爆发危险性评价数据库、知识库和危险性评价数字环境模型.在ArcGIS的支持下对所选取因子进行详细分析,得到海子沟流域泥石流危险性评价图,为海子沟流域泥石流防治工程提供了重要的依据.     

基于熵权和模糊评判的单沟泥石流危险性评价

基于对泥石流形成的多种因素分析,根据大、小型泥石流沟的实际特征,对大型泥石流沟选取了主沟长度、流域面积等9个评价指标,对小型泥石流沟选取了沟床平均宽度、主沟纵坡降等8个评价指标,利用熵权分析法和模糊综合评判法对单沟泥石流进行危险性评价.结果显示:小型泥石流沟对应于轻度、中度、高度、极高度危险等级,模糊评判结果所占比例分别为40.0%,26.7%,26.7%,6.7%,熵权评判结果所占比例分别为33.3%,46.7%,20%,0,两种评价结果一致率达到80%;大型泥石流沟两种评价结果一致率达到78%,因此两种评价结果的吻合程度较高.对于存在差异的泥石流沟进行野外实地查勘和历年灾情分析,表明基于模糊评判法对于单沟泥石流危险性评价的结果更为真实可靠,能够为泥石流灾害防治提供科学依据.     

基于模糊综合评判法的震区泥石流危险度评价

"5.12"汶川地震导致震区泥石流沟的活动性增强,使得泥石流的危险性发生了变化.泥石流是由多种因素综合作用的结果,是一个复杂的"模糊"系统,选取7个因子作为泥石流危险性评判因子,运用模糊综合评判法,对龙池的8条泥石流沟进行危险度评价.评价结果与实际情况基本相符,表明将模糊综合评判法应用于泥石流危险度评价是科学的和可靠的...     

基于关键驱动力的怒江州兰坪县泥石流危险性评价

近年来,云南怒江地区多次暴发大规模灾害性泥石流,造成了重大人员伤亡和财产损失.文章选取矿产和水电资源丰富的兰坪县泥石流为研究对象,通过现场勘察,结合已有调查成果,明晰兰坪县泥石流空间分布格局;在此基础上,从地质驱动力、水动力和重力驱动力3方面构建基于关键驱动力的单沟泥石流危险性评价指标体系,运用层次分析法与GIS技术开展危险性评价.结果显示:兰坪县境内79条泥石流沟中,处于高危险性的有20条,中危险性30条,澜沧江右岸和左岸分别为高危险性和中危险性泥石流沟的集中区.进一步分析表明,兰坪县泥石流危险性高低受降水影响较大,从澜沧江右岸到左岸再到通甸河,降水逐渐减少,泥石流的危险性也逐渐降低;本研究结果可对兰坪县大型工程建设及保障运营安全等具有一定的指导意义.     

泸定县寨子沟泥石流基本特征及危险性评价

泸定县寨子沟泥石流是一条老泥石流沟,为科学评价其发展趋势及危险性,在现场调查的基础上,对该泥石流沟的形成条件、动力学特征及危险性进行了分析评价。结果表明,寨子沟泥石流的形成条件充分,属中度危险泥石流沟,并提出了相应的防治建议。     

基于模糊概率方法的泥石流危险性评价

为客观合理评价泥石流危险性,选取泥石流(可能)规模、泥石流发生频率、流域面积、主沟长度、流域最大相对高差、流域切割密度、主沟床弯曲系数、泥砂补给段长度比、24 h最大降雨量、人口密度等10个因子作为泥石流危险性评价指标,运用模糊概率方法建立了泥石流危险性评价模型,并对8条典型泥石流沟的危险性进行了评价.研究表明,模糊概率方法在继承模糊综合评判法的思想和优点的同时,克服了在实际应用中其评价因子权重取值的不确定性,从而为进行有效的泥石流灾害防治提供了可靠的科学依据.     

北川县五星沟泥石流危险性评价

利用灰色关联分析方法对北川县五星沟泥石流作了危险性评价。在综合考虑地形地貌、气象水文条件、人类工程活动等的基础上,选取了流域面积、主沟长度、植被覆盖率等7个指标作为北川县五星沟泥石流危险性的评价因子,通过对已知泥石流沟的危险性等级的关联度进行计算,进而得出比较序列与参考序列的关联性排序。最后将北川县五星沟信息序列作为比较序列加入其中,通过计算比较得出其危险等级,评价结果为中度危险。     

基于流域单元和信息量法的白龙江流域泥石流危险性评价

基于流域单元和信息量法对甘肃省白龙江流域泥石流危险性展开评价,采用区域内已知的309条泥石流沟对评价结果进行验证.结果表明:评价为中度和重度泥石流危险性的沟谷中有79%实际发生过泥石流活动,表明将流域单元和信息量法相结合的方法对泥石流危险性评价的结果基本上符合研究区泥石流的现状,而且评价精度和准度较高;地震动峰值加速度、流域面积和归一化植被指数是影响白龙江流域泥石流危险性评价结果的主要因素;中度及重度危险性的沟谷主要集中分布于宕昌县、舟曲县、武都区和文县,其中以宕昌县、武都区和舟曲县3个地区最为严重,文县次之,迭部县主要为轻度及以下.     

兴宁乌石坑沟特大矿渣型泥石流灾害特征及危险性评价

广东省兴宁乌石坑沟是一条典型的矿渣型泥石流沟,物源规模巨大,泥石流频繁且危害性大,因此对其科学预测和危险性评价具有重要意义。在现场详细调查和大量测量的基础上,对该沟泥石流的成因机制及动力学参数进行了分析、计算。再通过对矿渣型泥石流各影响因子进行定量分析,选取堆渣规模、流域面积、渣堆稳定性等9个评价因子,建立基于层次分析法对泥石流危险度评价的数学评价模型,对研究区泥石流进行了危险性评价。研究表明,该沟泥石流危险度为0.626,属高度危险,评价结果与实际情况相吻合,可为乌石坑沟泥石流防治工程提供可靠的依据。     

基于动力过程的单沟泥石流危险性评价方法

摘 要：单沟泥石流危险性分区对泥石流滩地合理开发利用和灾害精细化管理具有重要意义。目前的泥石流危险性评价大多从孕灾环境入手，更像是易发性评价，且无法对泥石流危害范围进行危险性分区。本文在泥石流危害方式分析的基础上，提出了基于动力过程的单沟泥石流危险性评价方法。研究表明，泥石流的危害能力主要与泥深（H）和流速（V）密切相关，进而提出了以泥深（H）和动量（HV）为分区指标的单沟泥石流危险性评价方法。根据分区指标，将单沟泥石流的危险区划分为高、中、低三个等级；高危险区泥深H ≥ 1.5 m或动量HV ≥ 6 m2/s，低危险区泥深H < 0.5 m且动量HV < 1 m2/s，其它危险区均为中等危险区。最后，基于本文提出的评价方法对甘肃舟曲“8·7”特大泥石流进行了危险性分析，验证了方法的可行性和实用性。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to