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1.
湖北省城市体系分形特征及其规模结构研究   总被引:10,自引:0,他引:10  
在简要介绍分形理论的基础上,利用哲夫法规计算了湖北省城市体系三项规模指标——非农业人口数、全部工业总产值和社会商品零售总额的分维值,分析了分维值的变化和规模结构自反现状特征,提出了湖北省城市体系培育的方向.  相似文献   

2.
长江三角洲地区城镇体系的分形研究   总被引:9,自引:0,他引:9  
从城镇体系规模结构方面,计算了长江三角洲地区城镇体系的首位指数、城市规模分形分布的分维数,并讨论了长江三角洲地区城镇体系的等级规模结构及其特点;从城镇体系空间结构角度,计算长江三角洲地区城镇体系中心城市吸引力的分维值和空间结构的关联维数,分析其分形结构特征.最后,提出长江三角洲地区发展的方向:在发挥江浙沪比较优势的基础上,进行合理分工,优势互补,最终实现区域经济一体化,形成区域整合优势,带动整个长江三角洲地区的全面发展.  相似文献   

3.
根据分形理论和维数合成法,可算出陕北地区城镇体系位序——规模分维数和城镇体系空间结构分维数。计算结果表明,陕北地区总人口分布相对合理,非农业人口分布不太合理,城镇人口分布和理想分布差距较大,而且这个差距具有变大的趋势。对此,可根据城镇体系空间结构分维数,构建对应的城镇体系空间结构分形模型;以城镇体系空间结构分形模型为基础,建立城镇体系发展的数字化规划模式,使陕北地区城镇发展模式与地貌形态、人口分布和经济结构相适应,促进社会和谐发展。  相似文献   

4.
以渝东北三峡库区11个区县为例,基于分形理论从城镇体系规模结构方面,计算了渝东北三峡库区城镇体系的首位指数,城市规模分形分布的分维数;从城镇体系空间结构角度,计算了其空间结构的关联维数.结果表明:渝东北三峡库区城镇体系存在空间分形结构和分形特征;城镇体系首位城市万州的垄断特征不明显,中间位序城市数目较多,人口分布比较均衡;城镇空间布局较为分散,空间关联程度一般.最后基于分形理论的测算与分析结果,从优化区域内城镇体系结构和功能角度,提出了培育万州增长极、开发沿江城镇带、建设特色小城镇和完善交通与信息网络等建议.  相似文献   

5.
从分形理论在城市规模结构研究中的应用入手,以Hausdorff维数为依据,通过Zipf公式对东北地区三大城市群规模结构进行了分维测算.结果表明东北城市群具有分形特征,三个城市群人口分布比较均衡,首位城市规模不是很突出,中小城市发育比较成熟.最后基于分形理论的测算与分析结果,提出了城市群城市发展对策.  相似文献   

6.
城市等级体系的多重Zipf维数及其地理空间意义   总被引:9,自引:1,他引:9  
基于城市等级体系的分形递归模型Pm=P1r1-mp,m=f1rm-1f及其等价形式三参数Zipf定律P(r)=C(r-α)-dz提出关于城市位序-规模分布的多分形模型,得到多分维谱的二标度表达形式Dq=ln[pq+(1-p)q]/[(1-q)lnrf],这里p=P(2)/[P(2)+P(3)]为概率尺度(括号中的数字表示城市的位序,为对应城市的人口);然后借助Legendre变换给出相应的参量表达,包括质量指数τ(q)、关于质量的Lipschitz-Hlder指数α(q)以及指数支集的分维函数f(α).导出关于城市体系人口分布的空间维数谱模型Dp(q)=DqDf以及有关的参量表达式,实现了区域城市人口多分维的可计算性.多重Zipf维数模型不仅可以有效地统一中心地的等级阶梯与位序-规模法则反映的连续分布,而且可以揭示城市体系演化的更多信息和隐含法则.以美国城市体系(1998年的数据)为实证对象,给出了城市规模分布的多分维Dq以及f(α)曲线等部分数值和图谱.  相似文献   

7.
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   

8.
都市圈城市体系空间结构的分形研究   总被引:1,自引:0,他引:1  
利用分形理论中的聚集分维和网络分维计算长江三角洲、珠江三角洲和环渤海经济圈城市体系空间结构维数,并分析其分形结构特征。长江三角洲由于生态系统边缘效应和交通通讯网络的发达而表现出内部空间结构的紧致性。随着珠江三角洲社会经济发展和市场发育,其城市空间亦趋于集聚和整合。环渤海经济圈则由于社会经济活动集中于渤海湾地区而形成了差异较大的内外圈层,使城市体系空间结构最为松散。为此提出了要发展卫星城,构建广域交通体系,扩大城市容量,增强各二级中心集聚、辐射能力等改善措施。  相似文献   

9.
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   

10.
从分形理论在城镇体系研究中的应用入手,以Hausdorff维数为依据,借助Zipf公式对吉林省城镇体系规模结构进行了分维测算.结果表明,吉林省城镇体系具有分形特征,说明分形理论适合于吉林省城镇体系规模结构的测算分析.在此基础上分析了吉林省城镇规模结构的分布特点及其存在的问题.最后基于分形理论的测算与分析结果,提出了吉林省城镇体系的发展对策.  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.
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   

13.
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   

14.
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   

15.
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   

16.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

17.
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   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

20.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

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