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961.
天水城市扩张的时空特征及动因分析 总被引:4,自引:2,他引:2
以不同时期的天水市地形图和TM遥感影像为基础,提取城市建设用地信息。并利用年均扩展指数(AGI)分析各时期城市空间扩展的分异特征。结果表明:天水城市用地由小范围到大范围、AGI 强度由低到高再趋缓。1996 年前,城区人口密度一直下降,此后又开始上升,与AGI 的变化相对应。受“两山夹一川”的地形限制,天水经历了由二点向多点分散扩展、内部填充与沿河谷延伸的空间演变过程。形成了南北窄、东西长的带状格局,不同于平原型城市以同心圆外扩模式。不同时期城市扩张的动因不同,初期是人口和工商业迁入,中期是行政力量和市场机制,近期是人口、经济的增长带来的社会需求。为了适应重点开发的需要,天水需要走出河谷、开发新区,提升综合功能。 相似文献
962.
运用港口首位度和修正的赫希曼-赫芬达尔指数, 从箱流的角度对1998-2010 年中国集装箱港口体系的空间结构转型进行了定量测度。结果表明:① 集装箱港口体系的重心由珠三角地区向长三角地区缓慢转移;② 集装箱港口体系总体进入“边缘挑战阶段”, 箱流的分散化成为中国集装箱港口体系空间变化的主流倾向, 但7 大港区首位港的极辐作用存在显著差异;③ 中国集装箱港口体系空间结构呈现低级均衡、单门户、多门户并存的多样化特征, 其中, 长三角、珠三角地区形成集装箱多门户港口区域的空间结构已成事实。政府宏观调控与政策引导, 枢纽港资源瓶颈约束, 边缘港口的设施、服务趋同, 港航企业网络扩展和腹地交通网络拓展与完善等因素是多门户空间结构形成的主要动力。 相似文献
963.
Loss assessment and decision-making are essential for earthquake emergency rescues,and for scientific prediction of seismic damage and determination of rescue objectives.In practice,however,there exist some problems,such as basic data not being precise and rich enough and decision making not having systematic and complete criteria.This paper tries to solve these problems using the method of data indexation by constructing an index system for earthquake emergency loss assessment and decision-making. 相似文献
964.
一次强沙尘暴活动对中国城市空气质量的影响 总被引:5,自引:1,他引:4
对2006年4月8—12日发生在中国北方地区的一次强沙尘暴天气过程及其对中国大陆城市空气质量的影响进行了分析研究。结果表明:①造成此次沙尘天气过程的直接原因是伴随着西伯利亚强冷空气南下的冷锋自西北向东南方向的移动。沙尘暴鼎盛时期卫星观测的中国境内大气沙尘气溶胶指数(AI)的分布存在一个高值区和两个次高值区。高值区位于内蒙古西部地区、河西走廊和河套地区;两个次高值区分别位于塔克拉玛干沙漠及华北至东北地区。与此同时,地面观测的最小能见度小于10 km的气象站点分布最密集的地区也主要分布在上述3个区域。AI的分布与最小能见度的分布之间有着很好的一致性。②这次沙尘天气过程的影响范围主要在33°N以北。从西到东沙尘天气影响的程度逐渐减轻,受污染最严重的城市集中在西北地区东部。根据锋面过境时间与发生大气污染事件时间的对比可将受沙尘天气影响的城市大致分为两类:第一类城市大气污染事件发生在冷锋过境期间(Ⅰ类城市),第二类城市大气污染事件发生在冷锋过境前(Ⅱ类城市)。Ⅰ类城市受沙尘过程影响发生空气污染事件的持续时间相对较短,空气污染事件主要出现在锋面过境前后。Ⅱ类城市受沙尘过程影响发生空气污染事件的持续时间相对较长,空气污染事件的出现时间要明显超前于锋面过境时间。两类城市的共同特征是能见度与空气污染指数(API)之间存在着良好的反位相关系。 相似文献
965.
In this paper the Marine Fish Community Index (MFCI) for the assessment of ecological status of marine environment is proposed. The MFCI was divided into 4 typologies: Rocky subtidal; shallow, intermediate and deep soft-bottoms. Based on the typical community associated to each typology and the DPSIR analysis performed, a set of metrics were selected and tested through a multiple correlation matrix (Pearson’s coefficient) and the core ones included in the index. The MFCI was applied in all typologies and the scores obtained with each metric were analyzed. In order to test the robustness of the MFCI the final ecological value of each zone was recalculated by removing successively one metric at a time. The MFCI showed a sensitive and robust response in the ecological status assessment. Since it incorporates both functional and structural community information, the MFCI can be useful in the context of the Marine Strategy Framework Directive as well as in other contexts of conservation and sustainable management of the marine environment. 相似文献
966.
城市化是当今时代社会经济发展的主旋律与经济发展实现现代化的主要目标之一。在经济发达地区,工业化水平高、城镇密集、交通发达、土地利用空间高度集约化,也是沿海地区城市化的重要特点。然而,每个城市的用地空间在城市化过程中存在着非理性的扩展现象,甚至有些大城市地区用地失控的现象;使之城市边缘地区过度郊区化,无限制的蔓延扩展,开发区泛滥,造成生态环境恶化,非理性化的城市建设成本不断增加,社会与环境治理成本也不断加大。提出在经济发达地区内,大都市用地空间理性扩展的5个原则与5种解决的办法,在中国土地资源十分有限的国情条件下,大都市建设做到用地空间理性扩展以及城市化健康发展将起到重要的指导作用,具有十分重要的实践意义与学术价值。 相似文献
967.
This study extends the application of local spatial nonparametric prediction models to the estimation of recoverable gas volumes
in continuous-type gas plays to regimes where there is a single geologic trend. A transformation is presented, originally
proposed by Tomczak, that offsets the distortions caused by the trend. This article reports on numerical experiments that
compare predictive and classification performance of the local nonparametric prediction models based on the transformation
with models based on Euclidean distance. The transformation offers improvement in average root mean square error when the
trend is not severely misspecified. Because of the local nature of the models, even those based on Euclidean distance in the
presence of trends are reasonably robust. The tests based on other model performance metrics such as prediction error associated
with the high-grade tracts and the ability of the models to identify sites with the largest gas volumes also demonstrate the
robustness of both local modeling approaches.
相似文献
Emil D. AttanasiEmail: |
968.
In June 2014, the Ministry of Civil Affairs, the National Disaster Reduction Committee Office issued the “Statistical System of Large-scale Natural Disasters Damage and Loss” (SSLNDD&L), in which the standard statistical content and index were explored. Examined by several major natural disasters in recent years, such as Ludian earthquake (Ms 6.5) on 3 August 2014, Nepal earthquake (Ms 8.1) on 25 April 2015, SSLNDD&L provided good basis for post disaster recovery and reconstruction planning, but the direct guidance of reconstruction planning was still limited. Post Disaster Needs Assessment (PDNA), the mainstream of the international disaster needs assessment system, was taken as the main research object, and the content and characteristics of PDNA system were analyzed in detail. The comparison analysis was made from the objectives, contents and index system, evaluation methodology, evaluation parameters between the SSLNDD&L and PDNA. In the future, expanding and increasing various industries and local evaluation index focusing on recovery and reconstruction needs, optimizing the disaster assessment parameter database used for the multi-user such as the Central-Province-County scale, supporting the preparation of technical standard optimization evaluation process to form a complete assessment technical specification should be put forward as the future development of the SSLNDD&L. It is of great practical significance to optimize and perfect the content and index of the SSLNDD&L to better serve the decision making of the recovery and reconstruction after large-scale disasters, and to achieve international standards on large-scale disaster damage & loss statistics and assessment in China. 相似文献
969.
《Marine Policy》2017
Resource conflict is a common feature of coastal management. This conflict is often managed by using spatial planning tools to segregate uses, with access decisions made through a comparison of the economic costs and benefits of the competing sectors. These comparisons rarely include an in-depth analysis of the extent or nature of the conflict. One commonly experienced form of resource conflict in coastal communities involves professional fishing, recreational fishing and broader coastal tourism. In New South Wales, Australia the professional fishing industry is often seen as being in conflict with recreational fishing and tourism, and there are frequent calls to close areas to professional fishing, arguing that this will provide improved economic benefits to local communities. This research examined the relationships between the three sectors using economic valuations, qualitative interviews and a large-scale representative questionnaire of the general public. The results revealed highly interconnected and mutually supportive relationships, with professional fishing providing a range of services that benefit both tourism and recreational fishing. These results suggest that spatial management exercises that seek to segregate or remove one sector from an area, may be counterproductive to the interests of all these groups. Relying on economic valuations of each sector as if they stand alone is insufficient to adequately understand their roles in local communities. Resource allocation decisions should be based on evaluations that consider the interconnections between sectors, and consider whether negotiated sharing of resources may provide greater community benefits than excluding certain groups of users. 相似文献
970.
《Marine Policy》2017
Territorial Use Rights in Fisheries (TURFs) are gaining renewed attention as a potential tool for sustainable fisheries management in small-scale fisheries. This growing popularity comes despite the fact that there are still unresolved questions about the most effective TURF designs. One of the key questions is the role of TURF size in their efficacy both from ecological and social standpoints. This study explores the expected effects of existing TURF sizes on yields for TURF systems in Chile, México and Japan. The expected effect of larval dispersal and adult movement on yields was simulated for TURFs in each system. The results show that the analyzed TURF systems fall into three main categories: (a) TURFs that are of adequate size to eliminate the expected negative effects of both adult and larval movement, (b) TURFs that are large enough to eliminate the expected negative effects of adult movement, but not the effects of larval dispersal, and c) TURFs that are too small to eliminate the expected impacts on yield of both adult and larval movement. These analyses suggest that either existing models of TURF performance are incomplete or that there is significant scope for improved performance with altered TURF designs. Considering these alternatives, empirical evidence from the TURFs deemed too small suggests that complementary management tools can enhance TURF performance when natural or social constraints prevent the construction of TURFs of optimal size. 相似文献