Seismic response predictions of multi‐span steel bridges through pushover analysis

In the new trend of seismic design methodology, the static pushover analysis is recommended for simple or regular structures whilst the time‐history analysis is recommended for complex structures. To this end, the applicable range of the pushover analysis has to be clarified. This study aims at investigating the applicability of pushover analysis to multi‐span continuous bridge systems with thin‐walled steel piers. The focus is concentrated on the response demand predictions in longitudinal or transverse directions. The pushover analysis procedure for such structures is firstly summarized and then parametric studies are carried out on bridges with different types of superstructure‐pier bearing connections. The considered parameters, such as piers' stiffness distribution and pier–0.5ptdeck stiffness ratio, are varied to cover both regular and irregular structures. Finally, the relation of the applicability of pushover analysis to different structural formats is demonstrated and a criterion based on the higher modal contribution is proposed to quantitatively specify the applicable range. Copyright © 2003 John Wiley & Sons, Ltd.     

鄱阳湖组(第四系)的修订及特征

根据对鄱阳湖地区 Zk0 1钻孔柱状剖面的研究 ,对鄱阳湖组的定义进行修订、补充 ,认为鄱阳湖组为一套以青灰色淤泥质粘土、黄褐色粘土、粉质粉土为主夹少量粉砂或细砂的湖泊—河口三角洲相沉积。年代地层为第四系全新统 ,底界年龄约 6 2 10± 12 5 a B.P.,开阔湖泊沉积始于 32 4 0± 180 a B.P.,且由北向南时代渐新 ,具有明显的穿时性     

Absence of Archean basement in the South Kunlun Block: Nd-Sr-O isotopic evidence from granitoids

Abstract   The West Kunlun mountain range along the northwestern margin of the Tibetan Plateau is crucial in understanding the early tectonic history of the region. It can be divided into the North and South Kunlun Blocks, of which the former is considered to be part of the Tarim Craton, whereas consensus was not reached on the nature and origin of the South Kunlun Block. Samples were collected from the 471 Ma Yirba Pluton, the 405 Ma North Kudi Pluton and the 214 Ma Arkarz Shan Intrusive Complex. These granitoids cover approximately 60% of the Kudi area in the South Kunlun Block. Sr, Nd, and O isotope compositions preclude significant involvement of mantle-derived magma in the genesis of these granitoids; therefore, they can be used to decipher the nature of lower–mid crust in the area. All samples give Mesoproterozoic Nd model ages (1.1–1.5 Ga) similar to those of the exposed metamorphic complex of this block but significantly different from those of the basement of the North Kunlun Block (2.8 Ga). This indicates that the South Kunlun Block does not have an Archean basement, and, thus, does not support the microcontinent model that suggests the South Kunlun Block was a microcontinent once separated from and later collided back with the North Kunlun Block.     

分形学:现代地图学的非线性数学分析方法

分析了地图学的传统数学分析方法，讨论了对象复杂性与方法简单化的矛盾，阐述了分形几何学，为现代地图学研究的定量化、系统化提供了新的数学分析方法。     

GPS精密定位中的海潮位移改正

根据海洋负荷潮理论，利用NAO99b全球海潮模型，计算了中国部分IGS站的海潮位移改正，并将海潮位移改正应用到GPS数据处理当中。在GAMIT软件的解算过程中，分别按加入和不加入海潮位移改正，对GPS基线分量和测站坐标分别进行了计算和比较分析。结果表明，海潮位移改正无论是对GPS基线分量还是对测站坐标，都有一定的影响。     

GIS支持下的全国广播电视信息管理系统的建设

介绍了GIS支持下的与专业信息充分结合的 ,为领导和专业技术人员提供决策支持等方面的实例。从技术和应用角度论述了服务于全国广播、电视信息管理和决策的“GIS支持下的全国广播电视覆盖信息管理系统”。对构成系统的数据组成、数据库结构、主要功能模块、应用效果等情况进行了系统论述     

苏州市轻轨精密工程控制网的建立

根据精密工程控制网的高精度要求，结合沉降地区的特点，进行GPS、精密水准作业中误差分析及精度控制分析，提出满足轻轨工程施工的控制方案。     

Lipid distribution in a subtropical southern China stalagmite as a record of soil ecosystem response to paleoclimate change

Lipid extracts from a 61.7-cm-long subtropical stalagmite in southern China, spanning the period of ca. 10,000–21,000 yr ago as constrained by U–Th dating, were analyzed using gas chromatography–mass spectrometry. The higher plants and microorganisms in the overlying soils contribute a proportion of n-alkanes identified in the stalagmite. The occurrence of LMW (lower molecular weight) n-alkanols and n-alkan-2-ones in the stalagmite was mainly related to the soil microorganisms. We suggest that HMW (higher molecular weight) n-alkanols and n-alkan-2-ones identified in the stalagmite originate from soil organics and reflect input from contemporary vegetation. Shifts in the ratio of LMW to HMW n-alkanols or n-alkan-2-ones indicative of the variation of soil ecosystems (e.g., microbial degradation of organic matter and/or the relative abundance of soil microorganisms to higher plants) are comparable with the subtropical alkenone-SST (sea surface temperature) record of the same period. The similar trends seen in the δ¹³C data and the lipid parameters in this stalagmite imply that the overlying soil ecosystem response to climate might be responsible for the variation of δ¹³C values.     

多元判据综合评估中期天气客观相似预报模式

提出一个对多元判据综合评估的中期天气客观相似预报模式。模式应用同中期天气过程的时间—空间尺度相适应的经过时间滤波的大气环流背景为客观判据，比较全面地评估了预报时刻前后多层次、多要素的大气环流动态变化的相似，通过定义相似指数综合评估在多元判据下样本的相似程度，从相似时域的历史样本中找到较佳相似的中期过程，预测未来l～10天的中期天气过程。模式检验和预报试验表明该模式具有预报技巧。     

我国能源消费结构变化与气候特征

文章利用多项式法将气候耗能量从能源消费总量中分离出来，用统计分析的方法探讨了气候耗能量与气候因子之间的关系及其变化。研究表明：从20世纪50年代到80年代初期，旱涝灾害是影响我国气候耗能量的主要气候因子，它们之间存在显著的线性相关关系，随着经济的发展和人民生活水平的提高，旱涝灾害对气候耗能量的影响逐渐减弱，气温对气候耗能量的影响日趋显著，目前正处于过渡时期。