大跨度拱桥施工稳定性的时变力学分析

大跨度拱桥在施工过程中的稳定性计算 ,是以施工期间变化着的不完整结构在不断改变的工作荷载下的分析为依据的。本文按时变力学分析方法 ,研究了大跨度拱桥的施工稳定性问题 ,较好地模拟了施工过程的结构行为。

温度影响线膨胀系数的识别方法

在大跨度斜拉桥的施工控制中 ,温度对结构内力和变形影响较大 ,混凝土和斜拉索的线膨胀系数是计算温度影响量的两个至关重要的参数。该文介绍了利用实测数据识别线膨胀系数的实用方法。

大跨度钢桥

简要介绍我国大跨度钢桥的发展情况，钢桥的特点和采用的材料及设计理论，并将我国焊接钢桥在发展过程中的主要疲劳研究成果作了概述。

大跨度开洞墙梁的简化设计应用

在设计下部为大空间、上部为小开间的建筑形式时,从整体结构上讲是不太合理的。考虑到甲方的要求,既满足建筑平面的布置又在结构上安全,笔者采用了设置转换层方案。运用普通框架程序计算,与有限元分析进行比较,寻找出在工程中较为实用、简单的计算方式,从目前使用情况来看。

特大跨度桥梁的发展

该文介绍了世界超大跨度桥梁──悬索桥和斜拉桥的发展过程，探讨了不断刷新跨度记录的原因，简述了酝酿中的更大跨度的桥梁．

大跨度主双曲钢管桁架天面结构安装实践

简要介绍了香港顺利村公园的主楼天面支撑跨度为 42m的大跨度主双曲钢管桁架的施工安装的方法 ,通过预先的方案对比分析 ,找出了最佳的施工方法组合 ,使工程节了大量资金及时间 。

ECHAM5-Simulated Impacts of Two Types of El Nio on the Winter Precipitation Anomalies in South China

The authors used an atmospheric general circulation model （AGCM） of European Centre Hamburg Model （ECHAM5.4） and investigated the possible impacts of eastern Pacific （EP） and central Pacific （CP） El Ni（n）o on the winter precipitation anomalies in South China.A composite analysis suggested much more rainfall during the mature phase of EP El Ni（n）o than in the case of CP El Ni（n）o,and their corresponding observed wet centers to be located in the southeast coast and the region to the south of the Yangtze River,respectively.Results obtained on the basis of model-sensitive run imply that the modelsimulated rainfall anomalies agree well with the observation,and the magnitude of simulated rainfall anomalies were found to be reduced when the amplitude of sea surface temperature anomaly （SSTA） forcing of EP and CP El Ni（n）o was cut down.These results imply that the rainfall anomaly in South China is very sensitive not only to the type of El Ni（n）o but also to its intensity.

Characteristics of Tropical Sea Surface Temperature Anomalies and Their Influences on the Onset of South China Sea Summer Monsoon

The characteristics of sea surface temperature anomalies （SSTAs） in the tropical oceans and their influences on the onset of South China Sea summer monsoon （SCSSM） have been studied.The anomaly of SST in tropical Pacific Ocean exerts persistence impact for one to three months on atmospheric circulations.If the warm pool becomes anomalously warmer during an earlier period from February to April,the SCSSM breaks out earlier,and vice versa.Singular value decomposition （SVD） and composite analysis have shown that,in La Ni（n）a pattern,the convection over Western Pacific will occur earlier and be stronger than normal,which favors the convergence at a lower layer over Western Pacific,as well as the strengthening of upwelling branch of Walker circulation,leading to an earlier burst of westerly in the southern South China Sea.Moreover,the convection in Sumatra appears earlier than normal and favors the westerly evolution in eastern Indian Ocean,resulting in the splitting of the subtropical high belt and an early onset of SCSSM.However,the atmospheric circulation anomaly is reversed in El Ni（n）o pattern.

Dropwise Condensation on a Rotating Condenser in Relation to Heat Transfer Intensification

A design of a rotating condenser is suggested. The maximum radius under the effect of rotation is estimated analytically .It is found that it decreases with the angular velocity. This in turn increases the rate of sweeping the surface by departing droplets. The appearance of droplets with smaller radii will be predominant. These small droplets offer small thermal resistances, thus enhancing heat transfer through the condenser surface. It is found also that the maximum radius is a function of the distance from the axis of the rotating condenser. Thus the value of the maximum radius under rotation is not unique. This in turn makes the heat flux through the condenser surface not to be uniform.

The Anomalous European Climates Linked to Different Euro-Atlantic Blocking

The impact on temperature and precipitation anomalies over the European continent of the different action centers of blocking events in the Euro-Atlantic sector was investigated. It was found that the position of the blocking action center in the Euro-Atlantic region seems to dominate European climates. When the center of the blocking action is in the Greenland region, there is a strong negative temperature anomaly over Central and Northern Europe, as well as a strong positive precipitation anomaly over southern Europe. However, there tends to be a strong negative temperature anomaly in the west(east) part of Europe when the center of the blocking action is shifted to the Eastern Atlantic and west Europe(east Europe). In particular, when the blocking action center is closer to the European continent, the fall in temperature becomes more evident over Central and south Europe than over other regions. Moreover, it was found that when the region where the blocking action center exists changes from the Eastern Atlantic and west Europe region to the east Europe region, the existing region of dominant positive precipitation anomalies varies from southwest Europe to southeast Europe and the Middle East.

Background concentrations of reactive gases and the impacts of long-range transport at the Jinsha regional atmospheric background station

Lorentz curve fittings are applied to frequency distributions of the concentrations of O3, CO, NOx and SO2 recorded at the Jinsha regional atmospheric background station （JSH） from June 2006 to July 2007, and the peak concentrations of these species for the different seasons are obtained. The peak concentrations are considered to be representative of different background levels for certain processes. The peak concentrations are compared with the corresponding mean （median） concentrations, and the suitability and limitations of the mean （median） values as the background levels are discussed. The mean （median） values might represent the background concentrations in the region under some circumstances, but in other cases these values often underestimate or overestimate the true background concentrations owing to the transport of pollutants and other factors. The effects of air masses transported from different regions on the pollutant background concentrations are obtained by analyzing the 72-hour backward trajectories of air masses 100m above the ground at JSH, These trajectories are estimated using the HYSPLIT model and then clustered for the measurement period. The spatial distribution and seasonal variations of trajectories and the corresponding mean concentrations of O3, SO〉 NOx and CO for different clusters are analyzed. After filtering the seasonal changes in pollutant concentrations, the relative influences of air masses from different regions are obtained. The results show that JSH can be used to obtain the atmospheric background information of different air masses originating from or passing over the Yangtze River Delta, Central South China and the Jianghan Plain. Air masses from Central China, South China, and the western Yangtze River Delta contribute significantly to O3 at JSH. Air masses from the north and northeast of JSH （i.e., the Jianghan Plain, Huang-Huai Plain and North China Plain） and the south （Central South China） contribute significantly to SO2, CO and NOx concentrations. Air masses originating from the ocean often bring clean air. Air masses originating from high altitudes over northwestern regions often have lower CO and NO3 concentrations, lower relative humidity, and higher concentrations of O3 and SO2.