基于空间分析的城市交通网络结构特征研究

城市交通网络是城市空间形态的基本骨架 ,交通网络的定量研究是对城市空间形态可控参数研究的重要方面。在GIS平台上利用拓扑分析可确定交通网络的整体层次结构及复杂程度 ,并可进一步分析交通网络的基本形态 ;长度维数主要描述网络密度的变化情况 ;而分枝维数主要描述网络内部结构的复杂程度及其连通情况。利用扩展维数分析城市交通网络结构有利于了解交通网络的动态变化过程。     

城市土地利用形态及其空间结构的分维描述方法

首先总结并论证了描述城市土地利用形态及其空间结构特征的两种分维；边界维数和半径维数。前者可用面积--周长关系和周长--尺度关系定义，测算方法有结构步长法、网格计数法等；后者则用面积--半径关系定义。借助数目-尺度关系测算。文章简述了这两种维数的地理几何意义并以实例说明了其应用方法。最后作者建议采用网络维数包括信息维数对城市土地利用的空间形态作进一步描述。     

基于GIS的城市交通网络分形特征研究

针对目前城市分形研究注重城市体系，对大都市城市个体形态生成演化的分形本质研究相对滞后的特点，尝试通过城市交通网络结构演化这一新的层面，拓展城市演化的分形本质研究，简要介绍了交通网络空间结构的分形测度-半径维度的定义，地理意义与测算方法，以上海基础交通网络信息GIS为支撑，分别对上海城市全域，浦西、浦东两分地域，几个行政城区进行了分形维数测算，结果表明，就城市全域而言，依据原城市“中心”与新开发的浦东陆家嘴“中心”所测算的分维数分别为1.56与1.66，二者相接近，也与国外一些相似的研究结果报道一致，表明交通网络存在分形本质的城市共性，就浦东浦西两分割地域而言，开发历史悠久的浦西中心城区，交通网络密度与复杂度远高于浦东地区，反映在分形维数上浦西1.57远高于浦东的1.37，就行政辖区而言，历史久远的中央商务区所在的卢湾、静安两区。分维数高于新发展的宝山、闵行，突显了老建成区的道路，交通网络的复杂性特征，论证了分形理论在城市内部结构和形态演变研究中的可应用性，初步揭示了上海交通网络空间结构在全市地域和有关行政区内的分形特征，讨论了交通网络的空间结构与经济发展的联系。     

城市土地利用形态的分维刻画方法探讨

首先总结并论证了描述城市土地利用形态及其空间结构特征的两种分维：边界维数和半径维数。前者可用面积－周长关系和周长－尺度关系定义，测算方法有结构步长法等；后者则用面积－半径关系定义，借助数目－尺度关系进行测算。其次简述了两种分维的地理几何意义，并以实例说明其应用方法。最后建议采用网格维数包括信息维数对城市土地利用的空间形态做进一步的定量描述。     

基于GIS和空间句法的城市空间形态多尺度描述

空间拓扑关系是空间句法研究的基础．讨论了空间句法的系列变量，并以武汉市为例，提取武汉市的交通网络轴线地图，在GIS环境下讨论了不同尺度空间范围内的空间句法变量，得出空间可达性是评价城市空间形态的重要因子，而集成度是描述空间可达性的直接变量．利用空间句法变量可以进一步研究城市空间形态与人类活动的相互影响和相互关系。     

城市土地利用结构与形态的分形研究——以上海市中心城区为例

借助系统论中的信息论思想，分析近50年来上海中心城区土地利用结构的信息熵和均衡度；运用分形理论建立城市空间形态的分形结构模型，以边界维数和半径维数为依据对近50年来上海中心城区空间布局及形态的演化进行定量判定，探讨城市空间结构与形态的演变特征与规律；最后对上海中心城区土地利用结构和形态的演变机制进行了分析.     

分形理论在吉林省交通网络研究中的应用

运用分形理论,对吉林省的交通网络进行了定量分析.通过计算盒子维数和空间关联维数,分析了其网络覆盖形态及空间分布特征.结果表明:吉林省交通网络具有明显的分形特征,发育较为成熟,整体通达性较好,应充分利用发达的交通网络带动经济的发展.     

无机微孔膜分形性及分形维数的测定

无机膜的结构在三维空间上相互交错，大小不一，处于一种无序状态，在统计上它们具有一定相似性，遵从分形规律。本文提出了利用CLSM共焦激光扫描显微镜测定膜孔分形维数的实验手段及计算方法；由CLSM测得膜断面形貌等高线，利用小岛法原理，回归分形维数Df。分形维数可作为衡量膜孔形态复杂程度的定量参数。     

基于分形理论的煤层微观裂隙复杂程度评价

为定量描述煤层和上覆岩层微观断裂网络的复杂程度，以鄂尔多斯盆地大宁——吉县地区为例。借助显微镜和显微光度计分析其微观裂隙的发育规律；根据分形几何原理，采用改进的网格覆盖法．计算其微观裂隙分形维数。结果表明：该区煤层上覆岩石裂隙发育不大，连通性不强，有利于煤层气的储存；煤层裂隙较为发育，但闭合及充填的较多，不利于煤层气的运移；8#煤层的微观裂隙发育程度及均匀性总体上比5#煤层略高；岩层微观裂隙主要发育在午城、瑶曲和管头附近；同一位置的煤层与岩层的微观裂隙复杂程度呈负相关。该结果为进一步研究该区煤层气地质条件提供了依据。     

信号灯随机更新的城市交通网络模型

【目的】改进二维元胞自动机模型(BML模型),使其更好模拟实际城市交通网络。【方法】利用元胞自动机方法,建立信号灯随机更新的城市交通网络模型。【结果】数值模拟发现,信号灯的同步对城市交通网络的影响较大,且随机更新的引入使得网络系统的临界密度大幅度降低。【结论】同时调整信号灯的分布和信号变换周期能有效控制交通网络,解决由于信号灯随机更新所造成的系统临界密度变小的问题。     

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.     

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     

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.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

<正>~~     

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.     

Features of Women''s language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

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