钢筋混凝土框架结构抗震超强系数分析

基于我国建筑抗震规范要求设计的14栋代表不同抗震特征要求的多高层规则钢筋混凝土框架，通过静力弹塑性分析详细地评估了框架结构的体系超强能力。分析中采用与抗震规范等效静力地震作用效应分布模式相同的单调递增侧向荷载，以二维平面框架为分析对象。分析结果表明地震分区对超强系数的影响较大；有填充墙框架比无填充墙框架的超强能力明显要大；内框架的超强能力比外框架的超强能力大；超强系数随框架楼层数的增加而减小。     

Study on snowmelt runoff simulation in the Kaidu River basin

Alpine snowmelt is an important generation mode for runoff in the source region of the Tarim River basin, which covers four subbasins characterized by large area, sparse gauge stations, mixed runoff supplied by snowmelt and rainfall, and remarkably spatially heterogeneous precipitation. Taking the Kaidu River basin as a research area, this study analyzes the influence of these characteristics on the variables and parameters of the Snow Runoff Model and discusses the corresponding determination strategy to improve the accuracy of snowmelt simulation and forecast. The results show that: (i) The temperature controls the overall tendency of simulated runoff and is dominant to simulation accuracy, as the measured daily mean temperature cannot represent the average level of the same elevation in the basin and that directly inputting it to model leads to inaccurate simulations. Based on the analysis of remote sensing snow maps and simulation results, it is reasonable to approximate the mean temperature with 0.5 time daily maximum temperature. (ii) For the conflict between the limited gauge sta-tion and remarkably spatial heterogeneity of rainfall, it is not realistic to compute rainfall for each elevation zone. After the measured rainfall is multiplied by a proper coefficient and adjusted with runoff coefficient for rainfall, the measured rainfall data can satisfy the model demands. (iii) Adjusting time lag according to the variation of snowmelt and rainfall position can improve the simulation precision of the flood peak process. (iv) Along with temperature, the rainfall increases but cannot be completely monitored by limited gauge stations, which results in precision deterioration.     

An equal area conversion model for rasterization of vector polygons

Vector-raster conversion is one of the classic research topics in the field of Geographical Information Systems (GIS). The algorithms commonly used in GIS are devoted to maintaining the vector polygons' shape characteristics, but neglect the gain and loss of a polygon's area, which is another important attribute. This paper proposes an equal-area conversion model based on an area compensation optimization principle. According to the topological relationship among polygons and boundary grids, a neighborhood compensation principle was adopted to assign the attributes of boundary grids and a global optimization algorithm was developed to minimize area distortion in the whole data set. Two experiments were designed and the results indicated that this algorithm not only guaranteed the area error is as small as possible, but also has the advantage as being adaptive to polygon shape and spatial structure.     

Suspended sediment load transport in the Mississippi River basin at St. Louis: temporal scaling and nonlinear determinism

This study investigates the dynamic behavior of suspended sediment load transport at different temporal scales in the Mississippi River basin. Data corresponding to five successively doubled temporal scales (i.e. daily, two‐day, four‐day, eight‐day and 16‐day) from the St. Louis gaging station in Missouri are analyzed. The investigation is focused on identifying possible low‐dimensional deterministic behavior in the suspended sediment load transport dynamics, with an aim towards reduction in model complexity. The correlation dimension method is used to identify low‐dimensional determinism. The suspended sediment load dynamics are represented through phase‐space reconstruction, and the variability is estimated using the (proximity of) reconstructed vectors in the phase space. The results indicate the presence of low‐dimensional determinism in the suspended sediment load series at each of the five temporal scales, with the variables dominantly governing the dynamics in the order of three or four. These results not only suggest the appropriateness of relatively simpler models but also hint at possible scale invariance in the suspended sediment load transport dynamics. Copyright © 2006 John Wiley & Sons, Ltd.     

Magmatic structures in the Krkonoše–Jizera Plutonic Complex,Bohemian Massif: evidence for localized multiphase flow and small-scale thermal–mechanical instabilities in a granitic magma chamber

The present paper examines magmatic structures in the Jizera and Liberec granites of the Krkonoše–Jizera Plutonic Complex, Bohemian Massif. The magmatic structures are here interpreted to preserve direct field evidence for highly localized magma flow and other processes in crystal-rich mushes, and to capture the evolution of physical processes in an ancient granitic magma chamber. We propose that after chamber-wide mixing and hybridization, as suggested by recent petrological studies, laminar magma flow became highly localized to weaker channel-like domains within the higher-strength crystal framework. Mafic schlieren formed at flow rims, and their formation presumably involved gravitational settling and velocity gradient flow sorting coupled with interstitial melt escape. Local thermal or compositional convection may have resulted in the formation of vertical schlieren tubes and ladder dikes whereas subhorizontal tubes or channels formed during flow driven by lateral gradients in magma pressure. After the cessation or deceleration of channel flow, gravity-driven processes (settling of crystals and enclaves, gravitational differentiation, development of downward dripping instabilities), accompanied by compaction, filter pressing and melt segregation, dominated in the crystal mush within the flow channels. Subsequently, magmatic folds developed in schlieren layers and the magma chamber recorded complex, late magmatic strains at high magma crystallinities. Late-stage magma pulsing into localized submagmatic cracks represents the latest events of magmatic history of the chamber prior to its final crystallization. We emphasize that the most favorable environments for the formation and preservation of magmatic structures, such as those hosted in the Jizera and Liberec granites, are slowly cooling crystal-rich mushes. Therefore, where preserved in plutons, these structures may lend strong support for a “mush model” of magmatic systems.     

河南范县M_L4.7级地震的启示

2006年4月9日,在河南省范县(35o40’N,115o24’E)发生ML4.7级地震,地震的宏观震中位于河南省范县的王楼乡、辛庄乡以及濮阳县的濮城镇,震中烈度Ⅴ度。地震的有感范围较大,南起山东省的曹县,北至河北省的大名,西起河南省的濮阳县,东到山东省的郓城县,总面积大约10000余km2。地震虽然没有造成人员伤亡,但是却使许多没有抗震性能的农村房屋和校舍遭到严重破坏,     

基于特征的城市交通网络非平面数据库的实现

针对基于特征的GIS及交换网络分析对数据结构的要求，着重讨论了如何建立基于交通网络特征的非平面拓扑，以改进地理分层－关系表设计方法及平面图弧段－节点数据结构在交通网络描述中的不足之处，并通过面向对象的方法、动态分段技术和关系表指针操作，结合实例描述了基于完整交通特征的非平面数据库的实现方法。     

拟合推估新解之一——两步解法

拟合推估的一般模式AmnmZ BrnrY=L Δ（1）通常用双拟合法则（2）求解，它有一定的缺陷^[1] 。本文提出一种解法，分为2步：1、将Y项并入Δ，在单拟合下求X的优估值X。2、把X项纳入L，Y作确定未知量，也在单拟合下求其估值Y。