钢筋混凝土框架结构抗震能力评估研究

根据我国建筑抗震设计规范，借鉴建筑结构强度和延性的抗震能力评估理念，提出了评估钢筋混凝土框架结构抗震能力的定量方法。在利用ETABS集成软件完成建筑结构内力分析后，应用本研究编写的结构抗震能力评估计算程序，实现了对钢筋混凝土框架结构抗震能力的定量评估。实例评估表明，该方法除可定量评估建筑结构抗震能力外，还可从评估结果了解造成抗震能力不足的原因。     

崇明地震台FGE磁通门磁力仪D分量基线值的确定

基线值是考察记录仪运行是否稳定可靠的一个重要指标。本文以记录仪的D分量为例,通过认真仔细地分析与探索,使用数据处理的方法,解决了崇明台FGE磁通门磁力仪基线值不稳定的问题。这对基线值的确定和日常的数据处理都具有一定的指导意义。     

溃变原理在雷暴天气预报中的应用

本文以欧阳首承教授“不损伤信息”的落区和落点结构分析方法，对四川省广汉地区的间断、持续性雷暴天气进行了具体地分析和预测。结果表明，该方法不仅可揭示天气的转折性变化，并使用10分钟一次数据的自记非规则信息，也已经能预测仅有半小时的局地雷暴天气。这不仅对民用、军用飞行有实际意义，也显示了充分利用自动气象站信息资源的必要性，并应改进目前自动气象站的记录读取方式。     

Geostatistics Analyst中空间内插方法的介绍

主流GIS软件ArcGIS 9的Geostatistics Analyst模块中所涉及的两大类空间内插方法:确 定性内插方法和地统计内插方法。结合该软件对各种插值方法的应用和处理进行了介绍,应用示例 比较各种内插方法的适用范围。     

沉桩挤土对孔隙水压力影响的试验研究

软粘土层深厚的地区进行预制桩沉桩将产生超静孔隙水压力的累积,过高的超静孔隙水压力使周围土体及建筑、地下管线等产生较大的变位,甚至产生破坏。以一次沉桩引起的超静孔隙水压力的原型试验,表明,单桩沉桩显著影响范围可达15m,沉桩引起的超静孔隙水压力水平可以达到甚至超过上覆有效土压力,并出现两个不同的相对稳定水平阶段。     

用最小绝对偏差方法(LAD)估计极值分布参数的探讨

数理统计问题中的最小绝对偏差方法(Least Absolute Deviation)由于具有良好的稳健性,近年来备受重视。本文所研究的是如何将最小绝对偏差法及非线性回归模型相结合,应用于极值分布的参数估计,并与经典的参数估计法相比较。通过对徐州市降雨量数据的研究表明,改进后的参数估计法不仅提高了模型拟和的精确度,而且有良好的稳定性,可以推广到相关气象要素的预测、预报研究中。其中,将LAD法运用于极值分布模型是一个新的尝试。     

Spatial distribution of metals in urban topsoils of Xuzhou (China): controlling factors and environmental implications

The contamination of soils by metals from various sources is a subject of increasing concern in recent times. Twenty-eight elements (Fe, Ti, Cr, Al, Ga, Pb, Sc, Ba, Li, Cd, Be, Co, Cu, Mn, Ni, V, Zn, Mo, Pt, Pd, Au, As, Sb, Se, Hg, Bi, Ag and Sn) have been analyzed from urban topsoil from the city of Xuzhou. The concentrations of these analyzed elements have been correlated to some soil parameters such as organic matter, pH, cation exchange capacity, carbonate content, and granulometric fractions (clay, silt and sand). Results of the statistical analysis show a large variety and complexity in these relationships. The spatial distributions of these metal concentrations were also constructed using geographical information system. The spatial distribution patterns of the elements analyzed show that traffic and industrial activities are the principal anthropogenic pollutant sources.     

Nutrient fluxes induced by disturbance in Meiliang Bay of Lake Taihu

A wave flume experiment was conducted to study nutrient fluxes at water-sediment interface of Meiliang Bay under different hydrodynamic conditions. The results reveal that hydrodynamics has remarkable effects on nutrient fluxes in this area. With a bottom wave stress of 0.019 N m^?2 (equivalent to disturbance caused by wind SE 5–7 m s^?1 at the sediment sample site of Meiliang Bay), the fluxes of TN, TDN and NH₄ ⁺-N were separately 1.92 × 10^?3, ?1.81 × 10^?4 and 5.28 × 10^?4 mg m^?2 s^?1 (positive for upward and negative for downward), but for TP, TDP and SRP, the fluxes were 5.69 × 10^?4, 1.68 × 10^?4 and ?1.29 × 10^?4 mg m^?2 s^?1. In order to calculate the released amount of nutrients based on these results, statistic analysis on the long-term meteorological data was conducted. The result shows that the maximum lasting time for wind SE 5–7 m s^?1 in this area is about 15 h in summer. Further calculation shows that 111 t TN, 32 t NH₄ ⁺-N, 34 t TP and 10 t TDP can be released into water (the sediment area was 47.45% of the whole surface area), resulting in concentration increase of 0.025, 0.007, 0.007 and 0.002 mg L^?1 separately. With stronger disturbance (bottom wave stress is 0.217 N m^?2 which is equivalent to disturbance caused by wind SE 10–11 m s^?1 at the same site), there has been significant increase of nutrient fluxes (1.16 × 10^?2, 6.76 × 10^?3, 1.14 × 10^?2 and 2.14 × 10^?3 mg m^?2 s^?1 for TN, DTN and NH₄ ⁺-N and TP). The exceptions were TDP with flux having a decrease (measured to be 9.54 × 10^?5 mg m^?2 s^?1) and SRP with flux having a small increase (measured to be 5.42 × 10^?5 mg m^?2 s^?1). The same statistic analysis on meteorological data reveal that the maximum lasting time for wind SE 10–11 m s^?1 is no more than 5 h. Based on the nutrient fluxes and the wind lasting-time, similar calculations were also made suggesting that 232 t TN, 134.9 t TDN, 228 t NH₄ ⁺-N, 42.7 t TP, 2.0 t TDP and 1.1 t SRP will be released from sediment at this hydrodynamic condition resulting in the concentration increases of 0.050, 0.029, 0.049, 0.009, 0.0004 and 0.0002 mg L^?1. Therefore in shallow lakes, surface disturbance can lead to significant increase of nutrient concentrations although some components in water column had negative flux with weak disturbance (e.g. TDN and SRP in this experiment). In this case, sediment looks to be a source of nutrients. These nutrients deposited in sediment can be carried or released into water with sediment resuspension or changes of environmental conditions at water-sediment interface, which can have great effects on aquatic ecosystem and is also the characteristics of shallow lakes.     

The 1920S Drought Recorded by Tree Rings and Historical Documents in the Semi-Arid and Arid Areas of Northern China

Using a network of tree-ring data, we show that there had been significant growth decline in the 1920s and early 1930s throughout a wide area of northern China. This growth depression is indicative of a severe and sustained drought in the 1920s and early 1930s, which was then confirmed with a variety of historical and instrumental records including hydrological, meteorological, and documentary evidence. The 1920s drought had a devastating effect not only on agricultural productivity, hydrological resources and society in the affected areas, but also on natural vegetation, as inferred from the tree-ring network and historical records. This research offers a picture of the drought calamity during the 1920s and early 1930s in northern China, and demonstrates the potential to identify spatial anomalies of large-scale drought using tree-ring networks in the semi-arid and arid areas of northern China.     

2005年川西"7.3"暴雨多普勒雷达回波个例分析

利用多普勒雷达的基本反射率图、径向速度图及相关资料,分析了7.3四川西部区域性暴雨天气过程,发现:就基本反射率而言,多普勒雷达与713数字化雷达所监测到的川西暴雨回波演变规律一致;径向速度图上,强降水区域存在明显的风向、风速的切变.