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1.
城市用地结构演变一直是学术界关注的焦点,但是已往学者主要关注于单体城市的研究,而对全球化背景下大都市区或城镇密集地区的研究尚显不足。为此,通过构造城市用地结构演变动力分析框架,并基于2000、2005和2010年《中国城市建设统计年鉴》的城市用地结构数据,对中国经济转型最快、市场化程度最高的长三角51个样本城市用地结构演变特征进行系统分析。结果表明:随着工业化与城市化进程演进,长三角城市正经历着以居住与工业用地增长为主导的空间重构;发达地区(或高级城市)凭借先发优势,其城市用地变化动态度逐渐减小,结构趋于成熟稳定;而相对落后地区(或低级城市)由于工业化进程相对较慢,其用地结构调整规律也较发达地区滞后。总体上,长三角地区城市用地结构总体变动趋于均等化,城市用地结构演变的"热点区"逐渐由发达地区大城市转向相对欠发达地区中小城市。通过对城市用地结构演变规律分析发现,在城市土地利用的复杂巨系统中,全球化与城市化共同驱动下的市场、政府和居民的行为共同促进了城市用地结构演变。  相似文献   

2.
西藏昌都地区土地利用结构熵值时序分析   总被引:17,自引:0,他引:17  
研究土地利用结构的变化反映了区域发展和人类活动的强度,是研究区域发展结构的核心内容之一。区域土地利用结构的变化是区域土地利用演变的直接体现,信息熵可以作为土地利用结构有序性的一种度量。借助信息熵理论对藏东地区1992~2004年土地利用结构熵进行了计算与分析,分析结果表明:研究区土地利用结构熵2004年较1992年有所增加,但是增长幅度较小,与全国和西部地区土地利用信息熵水平相比,藏东地区土地利用系统结构熵值较低,有序度较高。土地利用结构变化和地方政策因素是导致昌都地区土地利用结构熵值变化的直接动因,经济发展、人口增长等对土地系统熵值的时序变化也存在影响。信息熵理论反映某区域系统宏观尺度上的土地利用结构特征,对区域土地利用结构的调整有一定的指导和借鉴意义。该理论在区域土地利用结构分析中的应用研究有待进一步深入。  相似文献   

3.
通过对2007~2014年城市建设用地的数据处理与比较,得出泰安市城市建设用地发展变化特点,为旧城改造以及城市规划工作提供参考,为区域城市建设结构提供依据。研究从两部分着手:一、运用土地利用动态度分析和Z-score标准化处理方法,研究泰安市城市建设用地数量变化特点。二、研究泰安市城市建设用地的信息熵值变化,分析该系统有序程度。研究结果表明:泰安市城市建设用地数量呈较稳定增长,与山东省年增长率保持较高程度的一致性;泰安市城市建设用地信息熵在时间上,具有动态演变特征。居住用地与工业用地面积变化是有序度变化的重要原因。  相似文献   

4.
区域用水结构演变规律与调控对策研究   总被引:1,自引:0,他引:1  
我国水资源严重短缺,在新的形势下,必须根据经济发展调整用水结构.本文以地处西北干旱区的榆林市为例,通过收集榆林市1990-2005年国民经济各行业用水量,结合信息熵原理,计算出不同年份用水量熵值及优势度动态演化情况.结果表明,榆林市用水系统熵值由1990年的0.569增加到2005年的0.667,总体呈上升趋势,表明榆林市用水结构趋向无序.同时,系统的均衡度也呈增加趋势,这表明当地用水系统在趋于无序发展的同时,用水系统的均衡程度有所提高,系统均衡性增强.从地区来看,南六县的用水系统熵值要高于北六县,且南六县用水系统熵值一直处于下降趋势,北六县则在波动中表现出一定的上升趋势,这与南六县长期从事特色农业,产业结构相对比较稳定,而北六县主要发展工业,导致用水结构中农业、工业、生活用水结构变化较大有关.最后,结合榆林市实际,提出"南护水源,北抑需求"的总体调控思路,通过建立权威、高效、协调的管理机制,推进水管理体制改革、加强立法和执法监督,规范水资源管理行为、因地制宜,调整和优化产业结构, 大力发展生态型低耗水产业、明确水权、建立水市场,制定合理水价、广泛宣传,积极引导,改变用水观念等措施,不断调整用水结构,最终实现经济社会可持续发展.  相似文献   

5.
重庆市城市用地与城市发展的互动关系   总被引:9,自引:1,他引:9  
对城市用地与城市发展之间的互动关系作了实证分析和理论探讨。抓住用地规模和用地结构两条主线,分析重庆市城市发展与城市用地之间的互动关系:城市经济发展和投资规模膨胀拉动了城市用地规模的增大,城市产业结构的调整则促进了城市用地结构和空间布局结构的逐步优化;城市用地总量的适当增加和用地结构的优化支持了城市的发展和人居环境的改善。在上基础上,认为城市用地与城市发展之间应保持良性互动关系,其判断标准是城市用地综合效益的逐步提高。  相似文献   

6.
重庆市城市用地与城市发展的互动关系   总被引:1,自引:0,他引:1  
对城市用地与城市发展之间的互动关系作了实证分析和理论探讨。抓住用地规模和用地结构两条主线 ,分析重庆市城市发展与城市用地之间的互动关系 :城市经济发展和投资规模膨胀拉动了城市用地规模的增大 ,城市产业结构的调整则促进了城市用地结构和空间布局结构的逐步优化 ;城市用地总量的适当增加和用地结构的优化支持了城市的发展和人居环境的改善。在此基础上 ,认为城市用地与城市发展之间应保持良性互动关系 ,其判断标准是城市用地综合效益的逐步提高  相似文献   

7.
根据1999~2007年土地利用统计、社会经济资料,借助信息熵原理及马尔科夫转移矩阵模型对梁平县土地利用结构动态演变进行了实例分析。结果表明,梁平县土地利用结构信息熵H经历了3个阶段:1999~2002年持续上升阶段、2002~2003年急速回落阶段及 2003~2007年波动阶段,土地利用结构无序程度发展态势不明显,均衡度变化与信息熵相似。用地类型主要由耕地转向林地、交通用地、居民点及工矿用地。定性分析了影响该县用地结构动态演变的政治经济政策,并利用主成分分析法对经济社会主要驱动因子进行了分析与探讨,得出影响该县用地结构动态演变的主要驱动力为:政治经济政策、经济发展。最后依据分析结果对梁平县未来发展做出定位:特色农业县--重点发展农林产品加工及文化生态旅游。  相似文献   

8.
基于信息熵的武汉市城市生态系统演化分析研究   总被引:1,自引:0,他引:1  
基于信息熵的分析方法,在前人的研究基础上,以武汉市2000~2010年城市生态系统发展为例,通过计算城市生态系统输入-输出熵流、代谢熵产生和系统总熵变,分析系统演化发展规律及原因;分别采用综合发展度和协调发展度评估城市的可持续发展水平,并将其进行指数化表征。分析结果表明:近11 a内系统熵流和总熵总体是呈现振荡式下降趋势,而熵产生先升后降,武汉市总体不断向着健康、有序方向发展,但有序度不稳定;近年来协调发展度和综合发展度二者保持同时增长,说明武汉市城市生态系统不断向着可持续方向发展,但武汉市目前仍处于初级协调发展水平  相似文献   

9.
基于城乡统筹视角,运用GIS空间技术、土地利用动态模型和多元回归分析,研究武汉市1996~2009年城乡建设用地数量结构变化、空间格局演变及驱动机制,是土地利用变化(LUCC)研究的重要内容之一,对区域城乡建设统筹规划及城乡社会经济统筹发展具有现实指导意义。结果显示:(1)研究期内武汉市城乡建设用地整体规模扩大,城镇建设用地比重上升,农村居民点用地比重下降;城市与建制镇扩张较快,主要源自对农用地的占用及独立工矿用地、农村居民点整理。(2)外城区城-乡建设用地数量、结构变化及类型转换特征对武汉市城乡建设用地变化起主导作用。(3)人口变化、经济增长、居民生活水平提高及政策等因素对武汉市内、外城区城-乡建设用地格局的驱动作用具有明显的区域差异和城乡差异  相似文献   

10.
基于耗散结构系统熵模型的产业有序发展研究   总被引:2,自引:0,他引:2  
"熵"和系统有序性之间存在着密切的关联关系,系统熵值的变化代表着系统有序发展程度的变化。对于封闭状态下的耗散结构系统来说,其内部要素之间的相互作用,会使系统的熵值增加,系统运行开始变得不稳定。具体表现为围绕目标而有效运行的秩序受到破坏,出现控制失灵、功能紊乱的无序现象。由此,构造耗散结构系统熵模型并测量系统熵值的变化,就可以有效反映系统运行的有序程度。本文研究发现,产业系统是一个典型的耗散结构系统,其发展的有序度可以用静态意义上的"结构熵"和动态意义上的"运行熵"来反映。因此,建立产业系统熵分析模型,进而解析产业系统的"结构熵"和"运行熵",可以有效解决产业系统有序发展程度的测定问题。利用我国风电产业发展的相关数据进行实证分析发现:在我国风电产业超高速发展的背后隐藏着一定程度的无序性,但随着产业整合的不断推进,其结构有序度将得到提高,运行有序度开始有所改进。  相似文献   

11.
Integration of indigenous knowledge and ethnoscientific approaches into contemporary frameworks for conservation and sustainable management of natural resources will become increasingly important in policies on an international and national level, both in countries that are industrialised and those that have a developing status. We set the scene on how this can be done by exploring the key conditions and dimensions of a dialogue between ȁ8ontologiesȁ9 and the roles, which ethnosciences could play in this process. First, the roles of ethnosciences in the context of sustainable development were analysed, placing emphasis on the implications arising when western sciences aspire to relate to indigenous forms of␣knowledge. Secondly, the contributions of ethnosciences to such an ȁ8inter- ontological dialogueȁ9 were explored, based on an ethnoecological study of the encounter of sciences and indigenous knowledge in the Andes of Bolivia, and reviewed experiences from mangrove systems in Kenya, India and Sri Lanka, and from case-studies in other ecosystems world-wide, incl. Australia, Burkina Faso, Ecuador, Ethiopia, Guatemala, Indonesia, Nepal, Niger, Philippines, Senegal, South-Africa and Tanzania.  相似文献   

12.
We review studies of the effects of low ambient ozone concentrations on morbidity that found a negative coefficient for ozone concentration. We call this a Paradoxical Ozone Association (POA). All studies were in regions with methyl ether in gasoline. All but one study carefully controlled for the effects of other criterion pollutants, so the phenomenon cannot be attributed to them. One was in southern California in mid-summer when ozone levels are highest. Because ozone is created by sunlight, the most plausible explanation for a POA would be an ambient pollutant that is rapidly destroyed by sunlight, such as methyl nitrite (MN). A previously published model of engine exhaust chemistry suggested methyl ether in the fuel will create MN in the exhaust. MN is known to be highly toxic, and closely related alkyl nitrites are known to induce respiratory sensitivity in humans. Support for the interpretation comes from many studies, including three linking asthma symptoms to methyl tertiary butyl ether (MTBE) and the observation that a POA has not been seen in regions without ether in gasoline. We also note that studies in southern California show a historical trend from more significant to less significant ozone-health associations. The timing of those changes is consistent with the known timing of the introduction of gasoline oxygenated with MTBE in that region.  相似文献   

13.
湘鄂赣地理位置优越,农业资源丰富,稻谷、茶叶、麻类、棉花、油料、柑桔和淡水产品、禽蛋、肉类等在我国居有重要的地位,因此,大力发展三省农业生产,对我国人民实现小康生活具有战略意义。今后,要加速专业化区域化进程。我们找出生产潜力所在:改造低产田、低产园、低产水面;开发“三高”技术;开垦荒地、荒山、荒水;适当提高复种指数。通过建设,三省主要农产品将自给有余,还可满足国内外市场的需要。努力方向:高效农业开发——综合农业开发,吨粮田开发,玉米带开发,饲料稻开发,山区开发;合理布局农业生产;深化农业商品基地建设,发展综合利用,搞活商品流通;全面提高农业现代化水平,加强农业社会服务体系。  相似文献   

14.
The use of quantitative data for constructing prognostic maps of the dynamics of ecosystem degradation and restoration by nonlinear simulation methods is a topical field of landscape ecology. This method of dynamic cartography is based on fiberwise comparison of data on the state of Chernye Zemli (the Kalmyk Republic, Russia) in different years and the detailed analysis of the period on which the prognosis was based. For this purpose, materials of repeated aerial and satellite photography obtained during a long period (1954–1993) were used. Comparison of maps characterizing the dynamics of Chernye Zemli between 1958 and 1993 allows prognostic electronic maps for the next 10–15 years (with a five-year interval) to be drawn and land prognosis for the next 20–30 years (1998–2023) to be obtained. Deceased  相似文献   

15.
Information regarding the distribution of volatile organic compound (VOC) concentrations and exposures is scarce, and there have been few, if any, studies using population-based samples from which representative estimates can be derived. This study characterizes distributions of personal exposures to ten different VOCs in the U.S. measured in the 1999-2000 National Health and Nutrition Examination Survey (NHANES). Personal VOC exposures were collected for 669 individuals over 2-3 days, and measurements were weighted to derive national-level statistics. Four common exposure sources were identified using factor analyses: gasoline vapor and vehicle exhaust, methyl tert-butyl ether (MBTE) as a gasoline additive, tap water disinfection products, and household cleaning products. Benzene, toluene, ethyl benzene, xylenes chloroform, and tetrachloroethene were fit to log-normal distributions with reasonably good agreement to observations. 1,4-Dichlorobenzene and trichloroethene were fit to Pareto distributions, and MTBE to Weibull distribution, but agreement was poor. However, distributions that attempt to match all of the VOC exposure data can lead to incorrect conclusions regarding the level and frequency of the higher exposures. Maximum Gumbel distributions gave generally good fits to extrema, however, they could not fully represent the highest exposures of the NHANES measurements. The analysis suggests that complete models for the distribution of VOC exposures require an approach that combines standard and extreme value distributions, and that carefully identifies outliers. This is the first study to provide national-level and representative statistics regarding the VOC exposures, and its results have important implications for risk assessment and probabilistic analyses.  相似文献   

16.
The Eastern Mediterranean region is among the regions which were predicted to become drier under IPCC climate scenarios. Here, we document a gradual reduction of rainfall and tree growth and the loss of rural springs during the last decades of the twentieth century. Years with severe drought are associated with very low tree growth (dendrochronology) and dry falling of springs as evidenced by interviews with local stakeholders. The paper discusses the consequences of accelerating drought on natural vegetation and agriculture and points at the interaction with fire dynamics and economy, both likely to enhance the drought effect.  相似文献   

17.
Variation in the reproduction of Varroa jacobsoni mite was studied in relation to the expansion of the range of its parasitism on the honeybee. Geographic differences in the seasonal dynamics of mite reproduction in the nests of bee families were revealed. Variation in the sex ratio of mites and the factors inhibiting their reproduction at the northern boundary of the honeybee range are considered. The forms of parthenogenetic reproduction in V. jacobsoni are discussed.  相似文献   

18.
The effect of long-term exposure to natural excretions of the European polecat on the morphological parameters and hormonal status of adult male Campbell hamsters (Phodopus campbelli) and dwarf hamsters (Ph. sungorus) was studied. Exposure to volatile components of natural excreta of a potential predator did not have any significant effect on hamsters. The combined influence of volatile and nonvolatile components of the polecat’s excretions caused physiological stress in Ph. campbelli, while in Ph. sungorus, on the contrary, an increase in thymus weight and the plasma testosterone level was recorded.  相似文献   

19.
The use of experimental settings to observe human behaviour in a controlled environment of incentives, rules and institutions, has been widely used by the behavioural sciences for sometime now, particularly by psychology and economics. In most cases the subjects are college students recruited for one to two hour decision making exercises in which, depending on their choices, they earn cash averaging US$ 20. In such exercises players face a set of feasible actions, rules and incentives (payoffs) involving different forms of social exchange with other people, and that in most cases involve some kind of externalities with incomplete contracts, such as in the case of common-pool resources situations. Depending on the ecological and institutional settings, the resource users face a set of feasible levels of extraction, a set of rules regarding the control or monitoring of individual use, and sometimes ways of imposing material or non-material costs or rewards to those breaking or following the rules. We brought the experimental lab to the field and invited about two hundred users of natural resources in three Colombian rural villages to participate in such decision making exercises and through these and other research instruments we learned about the ways they solve - or fail to - tragedies of the commons with different social institutions. Further, bringing the lab to the field allowed us to explore some of the limitations of existing models about human behaviour and its consequences for designing policies for conserving ecosystems and improving social welfare.  相似文献   

20.
The size of shells in some freshwater pulmonate mollusk species abundant in Western Siberia (Lymnaea fragilis, L. terebra, Planorbis planorbis, and Anisus leucostoma) is relatively large in the south and decreases in the north. It is supposed that this phenomenon is explained by the fact that the season with conditions allowing the growth of mollusks is shorter in the north than in the south of Western Siberia.  相似文献   

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