现代大地测量学中的垂线偏差

从大地测量学的角度论述了垂线偏差概念从传统到现代的发展和演变,比较全面地探讨了现代垂线偏差的含义和测定方法。通过对垂线偏差量级和误差大小的具体分析,得出结论一般长周期的、幅度较小的非潮汐变化要小于潮汐变化,但短周期的、幅度较大的非潮汐变化则可能与潮汐变化相当,个别地区甚至还会超过潮汐变化,这种情况完全可以用重复重力测量的方法检测到,这也说明重复测量的方法是可行的。     

Design of content-based retrieval system in remote sensing image database

IntroductionContent-based i mage retrieval ( CBIR)[1 ,2]technology was proposedin 1990s andit is a i m-age retrieval technology using i mage vision con-tents such as color ,texture ,shape ,spatial rela-tionship ,not usingi mage notationto searchi ma-ges .…     

Intermediately complex models for the hydrological interactions in the atmosphere-vegetation-soil system

This paper investigates the hydrological interactions in the atmosphere-evegetation-soil system by using the bucket model and several new simplified intermediately complex models. The results of mathematical analysis and numerical simulations show that these models, despite their simplicity, can very clearly reveal the essential features of the rather complex hydrological system of atmosphere-ecosystem-soil. For given atmospheric variables, these models clearly demonstrate multiple timescales, the “red shift” of response spectra, multi-equilibria and limit cycles, bifurcation, abrupt change, self-organization, recovery, “desertification”, and chaos. Most of these agree with observations. Especially, the weakening of “shading effect” of living canopy and the wilted biomass might be a major mechanism leading to the desertification in a relatively short period due to overgrazing, and the desertification in a relatively long period or in climate of change might be due to both Charney’s mechanism and the shading effect. These ideas could be validated with further numerical simulations. In the paper, some methods for improving the estimation of timescales in the soil water evolution responding to the forcing are also proposed.     

用双节点有限单元模拟渗流模型中的断裂与裂隙

将岩石结构力学中的三维节理单元的概念引入含裂隙系的渗流模型中,提出双节点渗流单元,用于模拟断层在地下岩体渗流场中的影响与作用,分析其物理意义,给出具体的单元渗流矩阵表达式     

Mechanism of Liquefaction Response in Sand–Silt Dynamic Centrifuge Tests

The process of dynamically induced liquefaction in two centrifuge soil models is analyzed. These models consist of saturated medium-dense sand overlain by a low permeability silt deposit, and represent prototypes of a level site and an embankment. The recorded lateral accelerations are employed to evaluate shear stress and strain histories at different elevations within the tested soil systems. These histories shed light on the involved liquefaction process, and the associated mechanisms of: (1) lateral deformation; (2) stiffness and strength degradation; and (3) possible densification and regain of stiffness, thereafter. The identified response patterns are found comparable to those documented by laboratory cyclic-loading tests.     

重力坝大孔口坝段抗震试验研究

以景洪水电站重力坝大孔口坝段为研究对象,通过输入没特性地震波的振动台模型试验和三维有限元分析,定量、定性地研究了大孔口坝段地震反应的特性。结果表明,对于大孔口坝段使用现行抗震规范反应谱曲线乍得的结果偏小;用振型迭加计算大孔坝段地震响应,参与迭加的振型不应少于五阶;应充分考虑不同地震特性的影响。     

中新世以来滇西高原隆升的沉积学证据

印度与欧亚大陆的碰撞不仅造就了青藏高原,带动周围地区不同程度的隆起,而且通过隆升和剥蚀向高原内部盆地和环绕高原的周缘盆地提供了巨量的硅质碎屑,这些盆地的沉积记录了青藏高原隆升历史和隆升机制［１～４］。青藏高原周缘地区已成为窥视其隆升历史和机制的重要窗...     

768地震记录器部分改造实施方案

７６８地震记录器是中国地震局７６８工程地震遥测台网配套设备之一,投入运行近２０年,为地震观测预报作出了不可磨灭的贡献。模拟地震观测离不了设备,今后数字地震观测若要有可见记录,同样要使用该设备。７６８地震记录器是７０年代产品,连续运行近２０年,设备严重...     

近江牡蛎铜锌超氧化物歧化酶的稳定性

在从近江牡蛎（Crassostrea rivularis)软体部分提纯得到纯度均一的铜锌超氧化物歧化酶（Cu,Zn-SOD)的基础上,对该酶的稳定性进行了研究,结果表明,该酶的水溶液在65℃时活力稳定,而该酶的干品在1℃／min程序升温时在58．4摄氏度有一尖锐的吸热峰,在pH为5．2－10．0的范围内该酶的活力不受影响。该酶对H2O2和KCN均敏感,且能耐受Tsuchihashi氏试剂的作用。一些氧化剂,还原剂,变性剂可改变酶的活力,差示扫描量热分析（Differential Scanning Calorimetry,DSC)发现,该酶在不同的升温速率下以及不同浓度的H2O2处理对酶的稳定性的影响与猪血,牛血SOD均有差异。     

东海污损生物群落研究 Ⅱ.数量组成和分布

东海表层板污损藻类月平均湿重为２１０．８ｇ／ｍ２。底层板污损动物的月平均湿重为４９４．５ｇ／ｍ２。以甲壳动物的数量占绝对优势,其次为腔肠动物,其余各类群占比例较小。不同类型海域污损藻类的月平均湿重为远岸区高于近岸区高于内湾区高于河口区。污损动物的月平均湿重为远岸区高于内湾区高于近岸区高于河口区。污损生物数量有明显的季节变化。藻类的季节变化大;污损动物以夏、秋数量最大,冬、春数量小