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1.
借助城市首位度指数、城市规模基尼系数、城市等级规模分布不平衡指数、位序-规模法则模型及相关分析法,对东北地区城市体系等级规模结构演变及机制进行了定量和定性研究.结果表明:东北地区城市体系中首位城市沈阳在发展的同时其他等级城市发展势头也很强劲;各规模等级城市人口总体处于均匀分布状态;城市规模分布日益均衡;城市规模分布具有明显的空间指向性;影响城市等级规模结构演变的因子主要有经济因素、交通因素、政策因素、自然因素,四大因素通过作用城市数量、城市规模、城市结构等方面,最终影响城市等级规模结构的演变.  相似文献   

2.
山东省城市体系规模分布的分形特征   总被引:1,自引:0,他引:1  
运用分形理论,借助Zipf公式分析了山东省城市体系规模分布的分形特征.研究认为,山东省城市体系规模分布具有分形特征,且区域差异性减小,城市体系规模分布趋于均衡;但首位城市规模相对较小,城市体系规模分布不尽合理.针对山东省城市体系规模分布的问题提出大、中、小城市协调发展,构建城市网络体系的对策.  相似文献   

3.
运用分形理论和方法,对海南省城镇体系的等级规模、分布特征和空间结构相关性进行实证研究.结果表明:海南省城镇体系中高等级城市数量少,城市规模小,等级低,城镇体系结构不健全,处于较低发展阶段;城镇体系等级规模结构松散,人口分布均衡性差,人口集中向大城市发展,区域发展依靠首位城市的带动为主;城镇间的空间关系不够紧密,空间相互作用不强,但海南省关联维数D接近1,空间分散程度并不高;城镇间的交通关联度较高,交通优势明显;海南省国际旅游岛建设促进了城镇体系的成长和优化.  相似文献   

4.
山东省城市规模结构及其分形特征   总被引:1,自引:0,他引:1  
王秀芬  王发曾 《河南科学》2009,27(10):1319-1324
选取1986,1991,1996,2001和2006年山东省17个地级市城市人口规模的资料,运用城市首位律、城市金字塔理论及位序-规模法则分析了山东省城市人口规模的变化,继而运用分形理论阐释了位序-规模曲线.结果显示,首位城市济南人口规模尚有可观的发展潜力,山东省城市体系属于典型的"双核心"结构;城市规模结构已从传统"金字塔形"向"纺锤形"转变;城市规模由分散趋于集中,人口分布趋向均衡,城市体系发育日益成熟;分形特征明显.  相似文献   

5.
以每个城市所开行的始发列车数量为衡量指标对中部六省的城市规模进行分析,将中部六省的80个城市划分为4个等级,形成以武汉为首位城市,南昌、长沙、太原和郑州为区域副中心城市的金字塔型城市体系,并运用ArcGIS地图软件绘制中部六省城市分布图,初步揭示中部城市的分布格局特点.  相似文献   

6.
通过测算20年来陕西城市体系等级规模分布的分维值,得出结论:陕西省城市体系规模分布符合分形特征;城市体系规模分布比较分散,人口分布呈不均衡态分布;整个城市体系的分形表现出中间层次的弱缺,存在城市规模等级结构的断层;城市体系等级差异虽有缓慢减小的趋势,但距离最优状态还很漫长。在对这些特征做出解释的基础上,认为应采取促进省内二级中心城市的发展、加快交通等基础设施体系的建设、加强城市体系的产业规划等措施促进城市体系等级规模结构的优化。  相似文献   

7.
以1998-2007年河南省城镇的非农业人口为特征量,运用级别分类、位序-规模法则、城市首位度指数和分形理论对河南省城市体系的规模序列进行了分析.研究表明:河南省城市体系首位城市的影响力不够,中间位序城镇数目较多,小城市人口规模低水平发育;规模序列结构的变化正处于波动起伏状态,属于发展的中级阶段;城市体系的规模分布属于位序-规模分布型,变化态势明显,但最大城市影响力仍需提高,没有形成稳定的过渡趋势.最后根据河南省规模序列的特征提出了河南省城市体系发展的建议.  相似文献   

8.
为了刻画山东省城市规模分布特点,以市区非农业人口作为城市规模的特征量,选取山东省建制城市1990—2008年的相关数据,采用首位度指数、帕雷托模型、基尼指数,借助ArcGIS 9.3对1990年以来山东省城市规模分布时空演变特征进行探讨.分析结果表明:1)不同规模城市数量的分布大致呈金字塔型,城市规模分布集中性呈现先减弱后增强的趋势;2)首位城市垄断功能较弱但趋于增强,中间位序城市比较发育,且分布均衡,规模结构差别趋于增强;3)城市体系的结构容量在不断增大;4)山东半岛城市群、济南都市圈、黄河三角洲城镇发展区、鲁南城镇带4个城镇化地域单元互动发展的格局逐渐清晰.在此基础上,提出了未来城市体系发展的相应建议.  相似文献   

9.
基于分形的福建省城市规模分布动态演变分析   总被引:3,自引:0,他引:3  
运用分形理论研究福建省城市体系规模分布的自相似性质和特征,借助分维及城市规模分布的均衡度指数分析福建省城市体系等级结构演化的动态特征,运用R/S分析方法对城市体系演化趋势作出预测,结果显示福建省城市规模分布的分维值有持续上升的趋势.论述了分维值上升的利弊,并根据分形优化原理提出改善福建省城市等级结构的措施.  相似文献   

10.
王慧颖 《科技信息》2010,(6):111-112
分形理论在城市规模分布的测算和预算上与传统方法相比有着明显的优势,本文简要介绍了分形理论,运用分形理论,借助zipf公式分析了内蒙古城市体系规模分布的分形特征,研究显示内蒙古城市体系规模分布不均衡,首位城市作用不明显,对于内蒙古城市体系发展提供了发展对策。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

13.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

18.
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.  相似文献   

19.
20.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

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