CLUSTERING ANALYSIS OF DEBRIS-FLOW STREAMS

The Chi-Chi earthquake in 1999 caused disastrous landslides, which triggered numerous debris flows and killed hundreds of people, A critical rainfall intensity line for each debris-flow stream is studied to prevent such a disaster. However, setting rainfall lines from incomplete data is difficult, so this study considered eight critical factors to group streams, such that streams within a cluster have similar rainfall lines. A genetic algorithm is applied to group 377 debris-flow streams selected from the center of an area affected by the Chi-Chi earthquake, These streams are grouped into seven clusters with different characteristics, The results reveal that the proposed method effectively groups debris-flow streams.     

内外支座为固支的钢筋砼环板的极限分析与设计

利用极限平衡条件，对内外支座为固支的环板进行了塑性极限分析，假定环板破坏时的塑性铰线为径环向．塑性铰线分割的各个板块为绝对刚体，每个板块满足各自的平衡条件，由板块的极限平衡方程，得出了环板极限状态时的内力计算公式，并通过试算得出了环板在不同的内外半径之比时，公式中的塑性铰线位置系数a1，a2的取值，使内外支座为固支的环板的计算问题大为简化。设计方法简单可行，便于在工程中应用。     

Chemical Composition of Urban Street Sediments and Its Sources

INTRODUCTIONBeijingfacesseveredustpollutionduetosuchsourcesasdustimportedfromwesterndeserts,industryandpowerplants,domesticcombustionprocessesandtraffic .Inthelastdecades ,theurbanpopulationhasgrowntomorethan10million .TheeconomicgrowthofChinahasalsoleftitsfootprintsinBeijing .Newindustrialzonesanddomesticar easweredeveloped ,inducinganincreasingtrafficcirculation(Shi,2 0 0 1) .Thedroughtclimateinalmostthewholeyear ,thestrongmonsoonsinwinterbringingdustsfromtheGobidesert,theheavytraffic…     

Preliminary Statistics of Temperatures and Pressures for Formation of Eclogites, Granulites and Peridotites in China

The rock-forming temperatures and pressures represent the p-T points of the local regions in the lithosphere at a certain age, providing some important information on rock formation. Based on the preliminary statistics on the temperatures and pressures for the formation of eclogites, granulites and peridotites in China, the variant ranges are given, in this paper, of temperatures, pressures and linear geothermal gradients of eclogites, granulites and peridotites. In addition, since the eclogite is different from granulite and peridotite in the p-T diagram, these three rocks can be classified into two groups: the first group includes eclogites and the second group granulites and peridotites. Then, the p-T correlation functions of these two groups of rocks are provided. Finally, the two groups of rocks have different geothermal gradients at the same pressure gradient or have different pressure gradients at the same geothermul gradient. The temperatures and pressures for the formation of the rocks can be calculated from the mineral chemical compositions, but the depths (H) for the rock formation can be calculated only under the hypotheses of given p-H (or T-H) correlation functions. The explanations for the ultrahigh pressure metamorphism vary obviously with different hypotheses.     

集合预报统计学后处理技术研究进展

近年来,随着集合预报的广泛应用,大量新颖的集合预报统计学后处理方法层出不穷,因此有必要对其进行系统地回顾。首先,对单变量集合预报统计后处理方法进行分类介绍,包括基于特定数学分布的参数化方法:逻辑回归、非均匀回归、贝叶斯模型平均、集合敷料法,以及灵活的非参数化方法:排序直方图订正、可靠性曲线订正、衰减平均偏差订正、分位数映射、分位数回归、概率匹配、频率匹配、最优百分位、最优评分法、逐成员订正、相似法、邻域法、基于对象的概率预报方法和虚拟降水法。其次,拓展到须考虑变量依赖性结构的多变量集合预报统计后处理方法,包括参数化的连接方法,以及非参数化的集合连接耦合和Schaake洗牌法。再次,介绍多模式集合和机器学习方法。最后,总结并讨论了常用的集合预报统计后处理方法使用中需要注意的问题。     

修正等应变假定下刚性桩复合地基固结特性分析

刚性桩复合地基固结特性是影响工程进度的重要因素。为研究外荷载作用下刚性桩复合地基固结特性，结合刚性桩和桩间土应力?应变特点对等应变假定进行修正。在此基础之上，考虑涂抹效应、桩间土和下卧层土体固结特性的影响，推导得到桩间土和下卧层土体固结微分方程。基于双层地基固结理论，考虑单级匀速施加荷载和附加应力沿深度变化等边界条件，推导得到其固结度解析解。最后，利用数值模拟方法对解析解进行验证，并对影响刚性桩复合地基固结特性的因素进行分析。结果表明：理论计算与数值模拟结果较为吻合；刚性桩复合地基固结速率受到贯入比影响较大，当贯入比较小时，与天然地基相比，其固结速率较小，贯入比较大且桩端阻力系数较小时，复合地基固结速率大于天然地基；随着贯入比、桩?土相对刚度和垫层?土体相对刚度的增大，复合地基整体固结速率加快；随着置换率的增大，复合地基整体固结速率降低。     

渭南市2015—2017年典型霾天气过程气象特征分析

综合利用地面空气污染监测资料、MICAPS资料、常规气象资料、探空资料、NCEP再分析资料,通过对2015—2017年渭南市11个典型霾天气过程进行分析,总结渭南市典型霾天气过程的大气环流背景特征,并运用统计学方法分析典型霾天气过程的气象要素特征。结果表明:典型持续性污染天气过程中细颗粒物(PM_(2.5))是PM_(10)的主要组成成分,PM_(2.5)的质量浓度明显高于粗颗粒物,严重污染期间PM_(2.5)和PM_(10)二者日变化明显且基本同步。严重污染期间,500 hPa欧亚中高纬度环流呈两槽一脊型,陕西处于暖脊前部、长波脊前底部,相应的700 hPa青藏高原上有短波槽,短波槽前有弱偏南气流发展;而空气质量转好时,中高纬度环流形势明显变化,陕西上空锋区加强,伴随地面东移南下冷空气的入侵,关中对流层低层偏北气流加强。PM_(2.5)质量浓度与过去1小时降水量、气温、海平面气压、10分钟平均风速负相关,与露点温度、相对湿度、总云量正相关。     

青海果洛龙洼金矿床矿化元素组合特征及找矿意义

青海果洛龙洼金矿床位于东昆仑造山带东段沟里地区,具有多元素共生特征,这些共生元素不仅具有综合利用价值,也是重要的找矿指示元素。文章依据工作中系统采集的81件样品的11种元素(Au、Hg、V、Mo、Ni、Cu、As、Co、Ag、W、Pb)测试数据,进行了元素的相关分析、聚类分析和因子分析,并分块段将各因子得分与矿体Au品位进行了对比研究,结合矿区地质情况进行了解译。结果表明,主成矿元素Au与Ag、Pb、Cu、Mo显著正相关,与Hg、W、As弱正相关。伴生元素中As与Hg、Pb与Ag为强正相关,Pb与Cu、Cu与Ag、W与Mo为正相关,Ni、Co与V元素呈弱正相关。因子分析结果显示,11种元素可分为四个因子组Au-Cu-Ag-Pb(F1)、W-Mo(F2)、Hg-As(F3)和Ni-Co-V(F4)。F1因子为中温多金属硫化物元素组合,在矿床主成矿阶段形成,该因子得分情况在矿区西部区域与矿体Au品位变化规律完全一致,因此,Au-Cu-Ag-Pb组合异常对矿区西部区域找矿具有指示意义。F2因子属高温岩浆热液元素组合,该因子上Au有一定载荷,推测矿区华力西-印支期花岗闪长岩对Au成矿具有重要意义。F3为低温热液元素组合,矿区自西往东分段统计结果显示,该因子得分变化情况与矿体Au品位变化规律具一致性,可运用As-Hg组合异常进行成矿预测。F4因子与地层中的基性火山组分有关,与其它元素具有不同的地球化学演化过程。因子得分统计结果显示,矿区中部是与Au相关多元素富集中心,该区段为多种成矿因素复合叠加的中心,应加强该处的勘查工作。     

基于地质统计学的地震反演冲积扇相研究——以新疆C油藏为例

新疆C油藏属于开发早期区块,井资料少、井距较大,采用地震反演等数据进行沉积相研究,可提高研究精度。采用约束稀疏脉冲反演和地质统计学反演两种方法进行地震反演研究,前者受到地震分辨率的限制,纵向上分辨率不能够满足研究需求;而后者可提高反演纵向上的分辨率。本文采用地质统计学反演的储层厚度分布图进行沉积相分析,得到沉积相平面展布图,并总结了沉积相模式,解决了勘探阶段沉积相难以描述等问题,并取得了较好的效果。     

Statistical Study of Trace Elemental Concentrations in Major Types of Organisms from Typical Chinese Coastal Waters

Frequency distribution characteristics of trace elements Fe. Mn, Zn, Cu. Sr and Ba are studied for the marine organisms collected from typical Chinese coastal waters and compared with those of major elements Ca and Mg. Nearly all the distributions for trace elements in macroalgae, benthic molluscs, crustaceans, cephalopods and different tissues of fish (muscle, liver and bone ) are found to show some degree of positive skewness, indicating a relatively large number of marine organisms with low concentrations for a particular element and only a few organisms with disproportionately high concentrations. Their distribution types are generally logarithmic normal distribution or nearly logarithmic normal distribution. Distribution of Ca is similar to that of trace elements, while Mg shows normal distribution. Average elemental concentrations of major types of organisms are calculated based on their frequency distributions.