Effects of structural characterizations on fragility functions of bridges subject to seismic shaking and lateral spreading

This paper evaluates the seismic vulnerability of different classes of typical bridges in California when subjected to seismic shaking or liquefaction-induced lateral spreading. The detailed structural configurations in terms of superstructure type, connection, continuity at support and foundation type, etc. render different damage resistant capability. Six classes of bridges are established based on their anticipated failure mechanisms under earthquake shaking. The numerical models that are capable of simulating the complex soil-structure interaction effects, nonlinear behavior of columns and connections are developed for each bridge class. The dynamic responses are obtained using nonlinear time history analyses for a suite of 250 earthquake motions with increasing intensity. An equivalent static analysis procedure is also implemented to evaluate the vulnerability of the bridges when subjected to liquefaction-induced lateral spreading. Fragility functions for each bridge class are derived and compared for both seismic shaking （based on nonlinear dynamic analyses） and lateral spreading （based on equivalent static analyses） for different performance states. The study finds that the fragility functions due to either ground shaking or lateral spreading show significant correlation with the structural characterizations, but differences emerge for ground shaking and lateral spreading conditions. Structural properties that will mostly affect the bridges＇ damage resistant capacity are also identified.     

基于Copula函数的东江流域3大水库丰枯遭遇分析

东江流域在广东省政治、经济和社会中占有重要地位,域内新丰江、枫树坝和白盆珠3大水库的来水量直接影响区域生产生活供水.面对水库群联合调度新要求,本文利用Copula函数构建了3大水库入库流量的二维和三维联合分布,分析其丰枯遭遇概率,主要结论如下:(1)3大水库两两间丰枯同步的概率大于丰枯异步的概率,非汛期丰枯同步的概率大于汛期.其中,白盆珠与新丰江、枫树坝丰枯异步的概率相对较大,这为其与另两个水库丰枯互补提供了可能;(2)三维联合分布显示,3大水库丰枯同步的概率在全年、汛期和非汛期均较大,依次为42.29%、41.74%和51.99%,其中同丰和同枯的概率远大于同平的概率.枫树坝与新丰江对下游具有补偿能力的概率分别为29.81%和23.03%,不具有补偿能力的概率分别为32.75%和22.32%;(3)利用3大水库的联合分布,可获得各水库不同入库流量遭遇的概率以及特定概率下各水库入库流量的可能组合,对3大水库联合优化调度具有重要的理论与实践价值.     

Minimization of drift force on a floating cylinder by optimizing the flexural rigidity of a concentric annular plate

The deployment of suitable configurations of mutually interacting floating bodies for efficiently controlling their hydrodynamic interactions towards the reduction of the wave drift forces and, thus, of the mooring lines’ loads, has, nowadays, gained a great scientific interest. In this paper, the hydrodynamic behaviour of a floating cylinder and a concentric annular flexible plate is analysed in the frequency domain aiming at the minimization of the drift forces acting on the cylinder by optimizing the flexural rigidity of the plate. The diffraction/radiation problem is solved using a higher-order boundary element method. The analysis is implemented assuming that both floating bodies oscillate freely in heave, while for the plate, flexible modes are, additionally, considered for describing its structural deformations. The required modes shapes are determined in vacuum (“dry” mode superposition approach) through analytical expressions. The flexural rigidity of the plate, D, is optimized at a specific wave number using a real-coded genetic algorithm. Initially, results are compared with numerical results of other investigators for the case of two rigid concentric floating cylinders. Next, extended results are presented, focusing on the effect of D, including its optimum value, on various physical quantities describing the behaviour of both the cylinder and the plate. Contrary to the isolated cylinder, the presence of the plate introduces sharp peaks in the variation pattern of the drift force of the cylinder, bounded at specific wave numbers, where resonance of the seiche mode of water motion in the annular cavity or of specific flexible modes of the plate occurs. However, by reducing D to its optimum value, the cylinder’s drift force obtains practically zero values at the target wave number, due to an efficient improvement of the wave field in the annular cavity around the cylinder. Moreover, a great reduction of the drift force compared to the isolated cylinder is achieved in the subsequent high frequency range.     

L-Q-T坐标下的P波与S波接收函数联合反演

接收函数分析是一种研究壳幔结构的主要技术手段。然而,沉积层引起的多次波会影响壳幔结构特征的可靠研究。与常规Z-R-T坐标下提取接收函数不同,本文尝试在L-Q-T坐标下提取P波与S波接收函数,并将二者进行联合反演。通过正演模拟讨论了沉积层厚度对接收函数的影响和实例分析位于具有巨厚沉积的渭河盆地和河套盆地的两个台站,验证了L-Q-T坐标下提取的P波接收函数能有效显示浅部地壳信息(如沉积层转换波信号),而P波与S波接收函数联合反演能够有效压制沉积层引起的多次波信号。显示了联合反演方法更具优势,除能获得界面深度信息,还能获取速度信息。     

三江源地区各类生态系统土壤的 性状及其形成能力

土壤形成是MA框架下生态系统支持功能的基本内容。运用GIS空间分析功能,测算了青海三江源区生态系统支持功能,结果表明:①源区土壤形成和生态系统支持功能呈从东南向西北降低的趋势;②源区各生态系统土壤形成的支持功能具有湿地生态系统>森林和草地生态系统>农田生态系统>荒漠和裸土地及裸岩石砾地的特点;③源区各生态系统支持功能具有从湿地生态系统、森林生态系统、草地生态系统、农田生态系统到荒漠和裸土地及裸岩石砾地依次降低的趋势;④草地生态系统退化诱导草地土壤形成功能的退化,进而驱使草地生态系统支持功能的降低;⑤强度人为干扰造成生态系统土壤各种性状向退化方向发展,土壤形成及生态系统支持功能下降。结果有助于丰富人们从土壤形成视角,对生态系统支持功能的理解和认识。     

MgSO4水合物溶解平衡时物相的热力学判别

硫酸镁易于形成水合物,例如前次报道我们获得并讨论的用于六元体系溶解度计算合理的单独电解质Pitzer参数,及四元交互体系Na+,K+//Cl-,NO3--H2O、K+,Mg2+//NO3-,SO24--H2O、K+,Mg2+//NO3-,Cl--H2O混合参数和它们的应用。此次报道对同离子四元体系K+//Cl-,NO3-,SO24--H2O、Mg2+//Cl-,NO3-,SO24--H2O的混合参数的研究及其在体系溶解度预测中的应用。     

热-流-固耦合建模过程

热-流-固耦合作用是存在高度非线性的复杂耦合作用。有关这三场的耦合作用研究在地石油工程、热资源开发、地下核废料存储安全、采矿工程等很多领域有着非常重要的应用价值。由于研究对象的不同,热流固耦合模型的形式存在差异,建立符合实际问题的三场耦合模型十分困难,文中在国内外学者对三场耦合模型理论研究的进展状况的基础上,通过一个例子,介绍了用adina建立模型的过程。     

基于核函数理论的系统聚类分析

为了完善系统聚类分析算法理论,使之具有区分数据集非线性集群特征的能力,将核函数理论和系统聚类分析算法有机结合,推导出基于核函数理论的系统聚类分析方法。其基本思路是:把样本从低维观测空间非线性变换至高维像空间,使样本变得线性可分;然后,应用核函数理论“隐式”地实现高维像空间的系统聚类分析。用Pb、Bi、Mo质量浓度作为化探异常的分类依据,对8处化探异常进行分类实验研究,在Pb、Bi、Mo两两组合的二维平面图中,8处化探异常明显地分为（1, 3, 8）,（2, 4）和（5, 6, 7）3个点群,用核系统聚类方法能够很好地区分出这3个点群;而传统系统聚类方法却把8处化探异常错分成（1, 3, 8, 6）和（2, 4, 5, 7）两个类。由此可见,核系统聚类方法的类群区分能力高于传统系统聚类方法。     

双功能地震记录仪报警器

本文阐述了地震仪双功能报警器的基本原理和结构特点。     

自然空间查询语言解译机制研究

基于自然语言的空间查询语言是空间数据库和智能GIS的重要研究领域。针对空间查询语言的特殊性就基于自然语言的空间查询语言的解译机制进行了细致的研究。在空间目标名称库、空间词汇库、空间查询句型模板库、空间语料库、查询结果模板库等空间知识库的支持下,介绍了如何用最大匹配分词技术对空间查询语句进行分词;说明了利用空间查询句型模板库中的句型对查询语句进行句法分析,最终解译出空间查询目标和相应空间操作的过程;详细阐述了如何进一步将这些空间目标和空间操作转换成中间空间查询语句(即扩展空间数据类型和空间函数的SQL),并由关系数据库执行查询;最后就如何选择文字或图形两种语言形式进行查询结果表示做了说明。