Recent Progress and Future Prospects in Solar Physics, and Their Relevance for Planet Earth     

Roger M. Bonnet  Anuschka pauluhn 《Surveys in Geophysics》2004,25(5-6):371-440

Understanding our star, the Sun, is of fundamental interest for life on Earth. In this paper, the status of knowledge in solar physics of roughly two decades ago is summarised, and the most recent developments in this very active field are shown, many of them achieved by means of space based missions. The Sun–Earth connection is described and, finally, an outlook on future solar research is given.  相似文献   

Electron microscopy study of the sakhaite from endogenous borate deposit in Hunan, China     

LIU Xiangwen    YANG Guangming  ZOU Huamin  QU Jing & ZHAO Wenxia . Graduate School  China University of Geosciences  Wuhan  China  . Test Center  China University of Geosciences  Wuhan  China  . Physics  Technology College  Wuhan University  Wuhan  China  . Test Center  Zhongshan University  Guangzhou  China 《中国科学D辑(英文版)》2004,47(3)

Sakhaite was first discovered by Ostrovskaya, Pertsev and Nikitina at Siberia in the former Soviet Union. By using the X-ray diffraction technique, they proved that the crystal system of sakhaite was cubic (a = 1.464 nm), its possible space groups were Fm3m, F432, F43m, Fm3, F23, and its crystal chemical for-mula was Ca48Mg16(CO3)16(BO3)28Cl4(OH)8 4H2O[1]. Chichagov, Simonov and Belov studied the crystal structure of synthetic sakhaite and determined that its space group was F4132, …  相似文献   

Frequency domain modal analysis of earthquake input energy to highly damped passive control structures     

Izuru Takewaki 《地震工程与结构动力学》2004,33(5):575-590

A new complex modal analysis‐based method is developed in the frequency domain for efficient computation of the earthquake input energy to a highly damped linear elastic passive control structure. The input energy to the structure during an earthquake is an important measure of seismic demand. Because of generality and applicability to non‐linear structures, the earthquake input energy has usually been computed in the time domain. It is shown here that the formulation of the earthquake input energy in the frequency domain is essential for deriving a bound on the earthquake input energy for a class of ground motions and for understanding the robustness of passively controlled structures to disturbances with various frequency contents. From the viewpoint of computational efficiency, a modal analysis‐based method is developed. The importance of overdamped modes in the energy computation of specific non‐proportionally damped models is demonstrated by comparing the energy transfer functions and the displacement transfer functions. Through numerical examinations for four recorded ground motions, it is shown that the modal analysis‐based method in the frequency domain is very efficient in the computation of the earthquake input energy. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

相空间中划分大尺度异常雨型的初步研究   总被引：5，自引：2，他引：5  

任宏利  高丽  张培群  李维京 《气象学报》2004,62(4):459-467

文中针对以往雨型研究中的不足 ,从动力学角度将相空间引入到大尺度异常雨型的划分 ,通过估计EOF相平面上的概率密度函数、并确定局部极大值区域来划分主要雨型。分析表明 ,新雨型不仅再现了传统的 3类雨型特征 ,还得到了其他分型 ,并且能够反映出异常降水分布的季节内低频变化 ;分别采用 10和 2 0d低通滤波数据划分的雨型形态比较接近 ,但其种类、持续性和季节内分布等特征存在一定差异 ;雨型的气候分布与季风雨带有一定对应关系 ,其形成与夏季风异常关系密切。通过对简单直观的二维相平面问题的探讨 ,不仅证实了在相空间中划分大尺度雨型的可行性 ,也为进一步在高维空间中讨论雨型问题提供了依据。  相似文献   

连续Domain的一个刻划     

周立涛 《南京气象学院学报》2004,27(1):128-130

弱逼近元在完备格中有许多重要的性质，对于刻划连续格、完全分配格起着重要的作用。在Domain中引入弱逼近元的概念，研究了弱逼近元的一个重要性质，从而得到连续Domain的一个充要条件。最后，以Scott开滤子为基础，得到了连续Domain的一个刻划定理。  相似文献   

近间距并行管线探测方法的效果对比   总被引：4，自引：0，他引：4  

赵献军  伍卓鹤 《物探与化探》2004,28(2):133-135

介绍了管线探测的几种方法,结合实例,对近间距并行管线的几种探测方法的效果进行了比较。  相似文献   

柯坪河流域地下水资源的有效利用方式探讨     

吕明松  和润萍 《新疆地质》2004,22(3):253-255

柯坪河流域分布于新疆境内，包括苏巴什盆地、柯坪盆地和阿恰山前地区．柯坪河是柯坪县最大的河流，上游名为苏巴什河，下游与红沙河汇合后称阿恰河．盆地与山前平原由柯坪河串起，水资源沿途不断汇入，并在不同河段有反复出露入渗．流域内无高山冰川，中山区降水是水资源的唯一来源．流域内水质普遍较差，溶解性总固体含量由北西向南东逐渐增高，当地居民生活饮用水供水水质不能满足生活饮用水标准．根据当地的地下水水资源特点，采取合适的管理利用方式，可使得较低溶解性总固体含量地下水资源能够更有效的被利用．  相似文献   

均匀色空间中绿色翡翠的色差   总被引：7，自引：0，他引：7  

郭颖  范静媛 《岩石矿物学杂志》2004,23(1):65-68

采用MPV-Ⅲ型显微光度计测定了32个翡翠样品的可见光吸收光谱，计算了部分样品的三刺激值。在此基础上引入色度学中均匀色空间及色差的概念，通过计算样品NBS值定量分析了不同翡翠样品间的绿色差异。结果表明，色差的定量计算可以反映样品间的真实颜色差别，并且不同于同色异谱指数，可作为绿色翡翠颜色鉴别中一种较为有效的定量方法。  相似文献   

Dislocating modernity: Identity, space and representations of street trade in Durban, South Africa     

E. Jeffrey Popke  Richard Ballard 《Geoforum》2004,35(1):99-110

South Africa’s cities have experienced dramatic changes over the past decade. Cities are now home to a multiracial population, and have been transformed by new forms of economic and social interaction. For some, these changes have become a significant source of fear and anxiety. In this paper, we examine reactions to urban spatial change in the city of Durban, as expressed in local newspapers and interviews with suburban residents. We describe how the discourses of urban change in Durban have centred on the increased presence of street traders within the city’s public spaces, and the various ways in which the activity of street trade has disrupted long-established modernist norms governing the occupation and use of the urban space. Specifically, we offer a detailed reading of three prominent narratives within the discussion of street traders in Durban--chaos, congestion and pollution. We argue that street traders have come to embody a wide range of more deeply seated cultural anxieties, which have been brought to the fore in the context of South Africa’s transition. These anxieties arise from the ways in which modern understandings of order, agency and subjectivity have been called into question by material changes in the city, and have implications for the nature of citizenship and civic engagement in post-apartheid South Africa.  相似文献   

Differential spaces of critical geography     

Kirsten Simonsen 《Geoforum》2004,35(5):525-528

This intervention address some of the social and epistemological mechanisms that construct an `international' writing space imbued with an Anglo-American hegemony. This is done by way of three examples, each making it possible to infer one of the general mechanisms at work. Taking off from the, comment, by the way of examples from Denmark, tries to illustrate how a truthful acknowledgement of the contextuality of geographical knowledges can multiply the spaces of critical geography--in the end enriching Anglo-American and non-Anglo-American debates alike.  相似文献