南水北调中线工程对湖北省的影响分析

南水北调中线工程是指从汉江的丹江口水库引水供给华北地区,同时考虑鄂、豫两省汉江唐白河流域和淮河流域的需水要求的战略性工程。汉江中下游地区是湖北省的粮仓和重要的产业基地,是汉江流域经济发展 的中心,但由于调水的影响,汉江丹口以下的流量及季节性分配将发生变化,航运、水质、农业灌溉、工业生产以及城市发展等将受到不同程度的影响,直接关系到湖北省在21世纪的持续发展。     

南水北调中线工程与长江中游地区水资源优化利用

我国是世界上水资源缺乏的国家之一 ,而且南北方河流水量差别很大 ,广大北方地区严重缺水 ,区域水资源的需求与供给极不匹配 [1,2 ] .因此 ,继续深入研究水资源的时空变化规律与流域规划 ,优化利用宝贵的水资源与探讨跨流域水量调配 ,是关系到我国社会经济可持续发展的重要课题     

只有南水北调能解决北方水资源短缺问题

水是生命之源、生产之要、生态之基。随着北方地区经济社会发展和城市化步伐加快,水资源短缺形势日益严峻,南水北调工程是当前解决北方水资源短缺问题的可行之路、必由之路。我国水资源短缺,人均水资源量为2100立方米,只有世界人均水平的约1/4,且时空分布不均,南方水多,北方水少。黄淮海流域是我国水资源承载能力与经济社会发展矛盾最为突出的地区,人均水资源量462立方米,仅为全国平均水平的21%,其中京津两     

跨流域调水及其对陆地水循环及水资源安全影响

跨流域调水是解决我国区域水资源配置的重要手段与途径,也是21世纪全球水系统计划科学前沿和我国北方水资源安全保障关注的重点问题.本文研讨了与气候变化与跨流域调水联系的陆地水系统概念,分析了与环境变化问题联系的国际发展态势.以跨长江、黄河、海河流域的南水北调中线调水区和北京受水区为典型区域,论述我国南水北调重大调水工程实施对陆地水循环影响及水资源安全保障研究关键科学问题,提出该复杂性问题研究的若干重点、研究途径与方法.     

南水北调西线工程对阿坝州所涉地区的影响及对策初探

南水北调工程是党中央、国务院在统筹考虑新世纪我国经济社会快速发展的迫切需要,统筹考虑人与自然全面协调、可持续发展的客观要求作出的一项重大战略策;而南水北调西线工程又是国家水资源配置"四横三纵"总体布局的重要组成部分,是我国实现经济社会可持续发展的战略工程,是中央统筹区域经济协调发展的重要战略举措,换句话说:西线调水既是维持黄河健康生命的迫切需要,又是支撑西北乃至华北地区社会经济可持续发展的重要保障措施。南水北调西线工程的实施,不仅能从根本上缓解我国北方地区长期缺水的矛盾,而且对改善生态环境和统筹区域发展,推动国民经济结构的战略性调整,促进经济、社会和生态协调发展,具有重大的现实意义和深远的历史意义。     

海河流域与水相关的生态环境承载力研究

为实现海河流域的可持续发展,需进行生态环境承载力研究.本文从水资源、生态环境、人口与经济的关系出发,针对海河流域生态环境恶化问题,探讨了与水相关的生态环境承载力的内涵、指标体系;提出时间序列与最优化理论相结合计算生态环境承载力的量化模型;得出海河流域现状处于生态环境严重超载状态;在南水北调、经济常规发展下,到2035年左右达到可承载的良好状态.     

南水北调对长江口生态环境影响的综合分析

 随着我国广大北方地区水资源短缺的矛盾日趋突出,以及我国综合国力的增强、大规模输水技术的突破,早在20世纪50年代提出的南水北调的宏伟设想,有望在21世纪中叶得到全面实现（包括东、中、西三线）.三峡水利枢纽是开发、治理长江的关键性工程,将于2009年建成运行。南水北调工程将对长江水资源进行调配,三峡水利枢纽在一定范围内将对其进行再调配。以三峡水利枢纽运行调度为基点,通过全面分析南水北调东、中、西三线工程对大通水文站及河口水文情势的影响,再对由此产生的生态与环境影响进行综合分析,明确减缓此种影响的规划方向,对于保障及促进长江河口地区的可持续发展、维护生态平衡具有重要意义。     

西北地区水资源可持续发展对策研究

西北地区包括新疆、青海、宁夏、甘肃、陕西省(自治区)的全部和内蒙古的西部地区。通过对该地区水资源利用的分析和评价,提出了水资源利用可持续发展的对策。把保护和改善生态环境工作放在首位,全方位加大节水力度。从长远发展看还需"开源",必须调水。即实现南水北调西线工程。     

IPCC_A1B情景下京杭运河21世纪中叶水资源条件时空演化

随着京杭大运河的申遗成功,关于京杭运河的全线"活化"及复航成为关注的重点,其关键是京杭运河沿线的水资源的调配和利用.本文采用IPCC的A1B情景,模拟了中国当代(20世纪后期,1981-2000年20年均值表示)和未来时期(21世纪中叶,2041-2060年20年均值表示)的降水量时空分布及演化特征,分析了京杭运河所经流域的水资源时空演化特征.发现京杭运河自南向北所经流域,长江流域水资源量会有所下降,淮河流域、黄河流域及海河流域的水资源量将略有上升.由此可以看出,京杭运河的全线复航关键是在尽早利用淮河流域及以南的水资源北上"济运",实现黄河以北运河的复航,同时在现有南水北调工程背景下尽可能恢复"南旺分水枢纽工程"及"北五湖"的水柜功能,实现京杭运河世界文化遗产的"活态"保存.     

基于可持续发展的黄河水资源利用研究

黄河是我国第二大河,是中华民族的母亲河,她创造了灿烂的华夏文明.作为我国北方重要的水资源,在我国国民经济和社会发展中占有重要的战略地位.目前,黄河水资源开发利用存在着许多突出问题,流域水资源严重短缺,供需矛盾十分尖锐.缓解水资源供需矛盾、实现水资源的可持续利用是黄河水资源管理的核心问题.黄河水资源可持续利用关系流域经济社会的可持续发展,关系改革与发展的大局,关系战略目标的实现和西部大开发战略的成败.因此,研究黄河水资源可持续利用具有重要的意义.本文是在对黄河水资源开发利用现状和水资源变化特点以及对水资源开发利用存在的主要问题分析的基础上.提出水资源可持续利用战略目标,并围绕此目标,全面分析探讨了实现水资源可持续利用对策.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme     

WIMAX与WI-FI技术分析及联合组网

介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。