高层钢框架-支撑结构二阶非线性随机地震响应分析   总被引：1，自引：0，他引：1  

陈兰  汤海波  梁启智 《地震工程与工程振动》2002,22(3):170-174

针对常用的高层钢框架－支撑结构，考虑材料非线性和几何非线性，建立了框架部分、支撑部分的二阶动力分析模型。用等效线性方法对结构进行非线性随机地震响应分析，结合工程算例，论述不同场地土、不同层数、不同支撑情况下，二阶效应对结构地震响应统计量的影响。  相似文献   

西苕溪流域不同土地类型下氮元素输移过程   总被引：60，自引：3，他引：60  

梁涛  张秀梅  章申  于兴修  王浩 《地理学报》2002,57(4):389-396

以西苕溪流域为研究对象,选择最有代表性的5种土地类型,模拟天然大暴雨,通过3次重复实验研究不同形态氮素随暴雨径流及径流沉积物的迁移过程,估算氮素在流域内不同土地利用/土地覆被条件下的损失率。研究结果表明,在相同的降雨条件下,氮素的流失速率和流失量随土地利用/土地覆被类型的不同表现出明显差异,地表径流水相总氮的流失量桑林最大,水田最小。水相不同形态的氮素流失量亦有所不同,悬浮颗粒态氮占地表径流水相总氮的70 %~90 %,水相溶解态氮的流失量以松林为最高,竹林、桑林和水田接近而且较低,不同类型的水相溶解态氮也随土地利用类型的不同表现出各自的特征。各土地类型单位面积、表层10 cm土壤氮素流失高达4.66~9.40 g·m-2,其中随径流沉积物相迁移的氮素占绝大部分(90 % 以上)。估算出的各土地利用类型总氮流失速率,地表径流水相为2.68~14.48 mg·m-2·min-1,径流沉积物相高达100.01~172.67 mg·m-2·min-1。  相似文献   

位移监测在滑坡时空运动研究中的应用   总被引：5，自引：0，他引：5  

靳晓光  王兰生  李晓红 《山地学报》2002,20(5):632-635

滑坡时空运动特征是滑坡地质体在内因和外因共同作用下，自一种状态向另一种状态转化的地质过程。滑坡位移监测是研究滑坡变形影响因素、动态规律及预测预报的主要途径，特别是滑坡深部位移监测，又为研究滑坡体的时空运动过程提供了重要信息。本文结合几个滑坡的深部位移监测实践，综合分析位移监测信息，研究滑坡体的时空运动特征及发展趋势，为滑坡时空运动系统研究及稳定性预测提供依据。  相似文献   

Modeling the relationship of land use change and some geophysical indicators for the interlock area of farming and pasturing in China     

DENG Xiangzheng  LIU Jiyuan  ZHUANG Dafang  ZHAN Jinyan  ZHAO Tao 《地理学报》2002,12(4):397-404

This paper discusses land-use changes in the interlock area of farming and pasturing (IAFP)in northern China. It presents detailed analyses of land-use features in the IAFP, which are controlled by the macro geomorphic units and geophysical conditions-constraints or advantages. Additionally, it selects some indicators, according to the availability in acquiring and processing their quantitative data, to analyze the canonical correlations between the typical conversion of grassland and geophysical conditions. The preliminary study indicates that the physical conditions are of great advantages to the development of grassland. There exists significant correlation between land use change and some geophysical conditions.  相似文献   

塔里木河中游天然植被的数量分类与排序研究   总被引：13，自引：4，他引：13  

李涛  尹林克  严成 《干旱区地理》2003,26(2):173-179

通过塔里木河中下游天然植被带的调查研究，应用数量分类(TWINSPAN)和排序(CCA)方法，对塔里木河中下游地区天然植被类型进行了划分，并探讨了决定该地区天然植物群落类型的主要环境因子。该地区天然植被可分为4个植被型组，4个植被型，6种植被亚型，9个群系，15个群丛。通过对8个环境因子的CCA排序分析，结果表明制约塔里木河中下游天然植被组成和结构的主导环境因子为地下水位、地下水矿化度、地下水酸碱度。通过CCA二维排序图将16种植物对干旱、盐碱的适应性划分5类型。21个样地在CCA二维排序图上可聚集成9个植物群落类群，即胡杨(Populus euphratica)群落、铃铛刺(Halimodendron halodendron)群落、库尔勒沙拐枣(Calligonum Kuerlese)群落、多枝柽柳(Tamarix ramosissima)群落、黑果枸杞(Lycium ruthenicum)群落、盐穗木(Halostashys caspica)群落、花花柴(Karelinia caspica)群落、疏叶骆驼剂(Alhagi sparsifolia)群落、罗布麻(Apocynum venetum)群落，与TWINSPAN结果中的群系分类单位一致。CCA连续排序与TWINSPAN分类结果吻合较好。9种植物群落类型中，能耐受最大盐胁迫的为盐穗木群落，能耐受最大干旱胁迫的为铃铛刺群落，能耐受最大地下水碱胁迫的为黑果枸杞群落。  相似文献   

美国外商制造业直接投资区域分异模式研究     

张弢 《世界地理研究》2003,12(1):30-35

本文以美国经济区为基本地域单元，以区位商和相关系数为主要研究指标，从一般投资区位和新建投资区位两方面研究了美国外商制造业直接投资区域分异模式。主要研究结论如下：外商制造业企业就业与美国制造业企业就业的区域分布很相似，但更倾向于集中在美国东南部；外商新建投资企业相对集中在新英格兰部分地区和东南部，得克萨斯和路易丝安那海岸地区，密苏里州和伊利诺伊州西部；外商新建企业倾向于分布在高人口密度区，但相关性没有美国本国新建企业强；外商新建投资企业与外商并购企业的分布略有不同。  相似文献   

A2O·3MoO3·3H2O(A＝Na、K)晶须的合成与表征          下载免费PDF全文

岳涛  朱黎霞  高世扬  夏树屏 《盐湖研究》2003,11(1):41-44

在常温条件下合成了两种钾、钠的钼酸盐晶须 ,用FT -IR和XRD对其结构进行了分析 ,SEM照片清晰表明这两种化合物为针状晶须。  相似文献   

Sand harm in Taklimakan Desert highway and sand control     

HAN Zhiwen  WANG Tao  SUN Qingwei  DONG Zhibao  WANG Xunming 《地理学报》2003,13(1):45-53

Reputed as a wonderful achievement of the world's highway construction history, the Taklimakan Desert highway is now facing serious sand drift encroachment problems due to its 447- km-long passage of sand sea consisting of crescent dunes, barchan chains, compound transverse dune ridges and complex megadunes. To solve some technical problems in the protection of the highway from sand drift encroachment, desert experts have been conducting the theoretical and applied studies on sand movement laws; causes, severities and time-space differentiation of sand drift damages; and control ways including mechanical, chemical and biological measures. In this paper the authors give an overall summary on the research contents and recent progress in the control of sand drift damages in China and hold that the theoretical research results and practices in the prevention of sand drift encroachment on the cross-desert highway represent a breakthrough and has an epoch-making significance. Since the construction of protective forest along the cross-desert highway requires large amount of ground water, what will be its environmental consequence and whether it can effectively halt sand drift encroachment on the highway forever are the questions to be studied urgently.  相似文献   

Microbial production of CO2 in red soil in Stone Forest National Park     

LIANG Fuyuan  SONG Linhua  TANG Tao 《地理学报》2003,13(2):250-256

Lunan stone forest is a kind of typical karst in China, which is mainly developed under red soil. In the winter of 1999, three study sites were chosen in stone forest national park according to vegetation cover, geomorphologic location and soil types. CO2 concentration was measured with Gastec pump at different depths of soil (20, 40, 60 cm) and at the same time soil samples were gathered and soil properties such as soil moisture, pH, soil organic content were analyzed and the total number of viable microbes were counted in laboratory. In the study, dependent variable was chosen as the mean soil log (PCO2), and soil properties were chosen as the independent variables. Multiple stepwise regression analysis showed that the total amount of microbes and soil moisture are the best indicators of the CO2 production, with the equation LOG(PCO2) = - 0.039(TNM) - 0.056(Mo) + 1.215 accounting for 86% of the variation of the soil CO2 concentration, where TNM is the total number of microbes in the soil and Mo is the moisture of soil sample.  相似文献   

SHRIMP Age and Geochemistry of the Bikou Volcanic Terrane: Implications for Neoproterozoic Tectonics on the Northern Margin of the Yangtze Craton   总被引：3，自引：0，他引：3  

A.D.HANSON  P.A.DRUSCHKE 《《地质学报》英文版》2003,77(4):479-490

The Bikou volcanic terrane is predominated by subalkaline tholeiitic lavas. Rock samples display lower initial ratios of Sr and Nd, 0.701248-0.704413 and 0.511080-0.512341 respectively. 207Pb and 208Pb are significantly enriched in the lavas. Most samples have positive εNd, which indicates that the magma was derived from EM-type mantle source, while a few samples with negative εNd indicate that there was contamination in the magma evolution. Magma differentiation is demonstrated by variations of LREE and LILE from depletion to enrichment. Additionally, normalized REE patterns and trace elements showed that lavas from the Bikou volcanic terrane have similar characteristics to those of basalts in arc settings caused by subduction and collision. Analyses showed that the Bikou volcanic terrane is a volcanic arc. New evidence proved that the Hengdan Group, north of the Bikou arc, is a turbidite terrane filling a forearc basin. Consequently, the Bikou volcanic terrane and the Hengdan turbidite terrane const  相似文献