1949年以来中国西部大城市制造业企业迁移特征、模式及机制——以兰州市为例   总被引：1，自引：0，他引：1  

郭杰  杨永春  冷炳荣 《地理研究》2012,31(10):1872-1886

企业迁移研究是经济地理学的重要论题之一, 是一种从微观个体出发理解产业空间格局演变及其形成机制的重要视角。利用兰州市制造业企业迁移信息, 从迁移规模、方式、距离及迁移跨度4个方面对城市制造业企业空间位移特征进行分析, 一定程度上揭示了新中国成立以来, 中国西部大城市制造业企业迁移的模式、路径及其形成机制。案例分析表明:中国西部大城市制造业企业迁移模式由计划经济时期单一行政主导的“梯度式”迁移模式向市场经济体制时期企业自主选择的“渐进式”迁移与政府先行主导的“跳跃式”迁移相结合的模式过渡, 大体上经历了向心式集中迁移、中心-外围互迁、外向型跨越式迁移3个阶段。研究还表明, 经济体制转型、地方政府自主经营权下放等宏观环境变化, 地方政策影响下的旧城更新、开发区建设、城市内外交通设施改善, 企业自身由于外部环境变化和内在扩张需求等诸多因素相互组合及综合作用, 在一定程度上共同推动了中国西部大城市制造业企业的空间迁移活动。  相似文献   

湖北省A级旅游景区的空间格局与优化   总被引：1，自引：0，他引：1  

王雯萱  谢双玉 《地域研究与开发》2012,31(2):124-128

为了充分利用、整合湖北旅游资源,运用图表法、空间计量分析法研究了湖北省125家A级旅游景区的空间结构特征及其与资源、行政区、交通、水系等要素之间的关系。结果表明:湖北省旅游景区趋于集聚型分布,以武汉市为中心呈现出一定的集聚规律;绝大多数旅游景区属于自然资源导向型;各地市(州、林区)景区的数量和等级组成、空间结构特征不同;旅游交通网不够完善;旅游景区有较明显的沿长江及其支流分布的趋势。进一步探讨了湖北省旅游景区空间布局中存在的问题,并提出优化方案。  相似文献   

转型期煤炭资源型城市空间重构——以淮南市、淮北市为例     

杨显明  焦华富 《地理学报》2016,71(8):1343-1356

以淮南市、淮北市4次城市规划中土地利用现状图为基础,运用ArcGIS软件对案例城市空间结构演化进程进行可视化表达和计量分析,揭示了煤炭资源型城市空间结构演化的过程、特征。通过对不同时点、不同用地类型的叠置分析,基于城市主要用地类型间的置换规模、频度、广度、强度及空间邻近关系,总结出商—居置换重构、商—工置换重构、居—工置换重构、工—居置换重构4种空间重构模式。当前,煤炭资源型城市以商—居置换重构和居—工置换重构为主,其空间置换面积大、频率高。最后,分析了经济发展、产业演替、体制改革、城市化、环境保护以及城市规划6个因素对煤炭资源型城市空间重构的影响,认为煤炭资源型城市内部空间重构是一种自我修复过程。  相似文献   

The effects of spatial targeting of fishing effort on the distribution of the Norway lobster,Nephrops norvegicus,on the Farn Deeps grounds,northeast England     

Michael C. Bell  Jon M. Elson  Julian T Addison 《新西兰海洋与淡水研究杂志》2013,47(5):1023-1037

Nephrops norvegicus is an essentially sedentary species of lobster that forms the basis of valuable fisheries in the northwest Atlantic and western Mediterranean. Fishers exploiting a sedentary stock are likely to visit the most profitable (highest catch rate) areas first. Such spatial targeting of fishing effort is likely to have important consequences for stock monitoring and assessment. We used underwater television surveys of Nephrops burrow densities on the Farn Deeps grounds, northeast England, to describe changes in abundance and distribution between the beginning and end of a winter fishing season. Above a threshold of c. 0.6 burrows m^–2, overwinter depletion increased with burrow density, consistent with fishing effort being targeted at the highest densities. A simple simulation model showed that this pattern of mortality is an expected consequence of spatially targeted fishing behaviour. The model also predicted that there is decreased spatial variability in density after fishing. An overall decrease in variability was not evident from the survey data, but geostatistical analysis indicated that there was “flattening” of the density profile along a north‐south axis, consistent with the dominant direction of commercial trawling. We concluded that Nephrops fishers are able to find and exploit the highest densities of their target species. A potential consequence is that catch per unit effort (CPUE) data used to monitor trends in this stock potentially could mask declines in stock abundance. CPUE might be more effective if analysed at finer spatial scales, but this is not currently possible. In the absence of these fine scale commercial data, fishery‐independent surveys (e.g., underwater television) are an important source of information on trends in stock abundance.  相似文献   

Within-reach spatial variability of snails and molluscivory by brown trout     

Joseph R Holomuzki 《新西兰海洋与淡水研究杂志》2013,47(3):189-197

Linking habitat distributions of prey to the probability of predation is important to understanding consumptive effects of predators on prey populations. This study reports how within-reach spatial variability of two snails, the hydrobiid Potamopyrgus antipodarum and the physid Physella acuta, was linked to habitat-based predation risk by young brown trout (Salmo trutta) of different age classes. Potamopyrgus is endemic to New Zealand streams and lakes, where it commonly co-exists with the invader P. acuta, but both snails are worldwide invaders to many freshwater systems. Examination of egested snails revealed Potamopyrgus and Physella were consumed in similar numbers within age classes. However, 10-month-old trout consumed, on average, fewer snails than 20-month-old trout, and 8-month-old trout ate essentially no snails, suggesting snails were a more important prey item for larger age-1 fish than smaller age-0 fish. No Physella were egested alive by any trout age class. However, 38% and 16% of the Potamopyrgus consumed were egested alive by 10- and 20-month-old trout, respectively, with some passing live after ~70 h in digestive tracts. Physella and the spiny-shell form of Potamopyrgus were significantly denser on macrophytes than on stony sediments in midchannel, and these habitat distributions affected their odds of consumption. Risk of consumption by trout was ~10 times greater for Physella than Potamopyrgus on stones, but their risk was similar in protective macrophytes. Odds of consumption were similar for spiny and smooth shell forms of Potamopyrgus on stones, suggesting spines do not provide protection from large predators like trout. My results suggest that brown trout can potentially exert stronger population regulatory effects on Physella than on Potamopyrgus and that these effects are partly mediated by macrophyte cover.  相似文献   

Study on far field wave patterns and their characteristics of Havelock form green function     

许勇  董文才  肖汶斌 《中国海洋工程》2013,27(3):283-298

A new mathematical integral representation including five integrals about the far field wave shape function of Havelock form translating-pulsating source is obtained by performing variable substitution. Constant-phase curves and propagation wave patterns are investigated by applying stationary phase analysis method to the new representation. Some findings are summarized as follows: (1) when 0< <0.25 (where is the Strouhal number), three types of stationary phase curves corresponding to three propagation wave patterns such as fan wave pattern, inner V and outer V wave patterns, are found in the integral representation. (2) When >0.25, besides three types of wave patterns such as a ring-faning wave pattern, a fan wave pattern and an inner V wave pattern, a new one called parallel wave pattern is also found which not only exists in the integrals about the ring-fan wave and fan wave, but also in the integrals whose interval is 0, . In addition, Characteristics about these parallel waves such as mathematical expressions, existence conditions, propagation directions and wave lengths are obtained, and cancellation relationships between these parallel waves are stated, which certificates the fact that there are no parallel waves existing in the far field.  相似文献   

RegCM3对全球变暖背景下中国东部季风降水和雨型变化的模拟          下载免费PDF全文

SHI Ying  GAO Xue-Jie  WANG Yong-Guang  Filippo GIORGI 《大气和海洋科学快报》2009,2(5):308-313

The authors investigate possible changes of monsoon rainfall and associated seasonal (June-JulyAugust) anomaly patterns over eastern China in the late 21st century under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES) A2 emission scenario as simulated by a high-resolution regional climate model (RegCM3) nested in a general circulation model (FvGCM/CCM3).Two sets of multi-decadal simulations are performed at 20-km grid spacing for present day and future climate conditions.Results show that the RegCM3 reproduces the mean rainfall distribution;however the evolution of the monsoon rain belt from South China to North China is not well simulated.Concerning the rain pattern classifications,RegCM3 overestimates the occurrence of Pattern 1 (excessive rainfall in northern China) and underestimates that of Pattern 2 (increased rainfall over the Huai River basin).Under future climate conditions,RegCM3 projects less occurrence of Pattern 1,more of Pattern 2,and little change of Pattern 3 (rainfall increase along the Yangtze River).These results indicate that there might be increased rainfall over the Huai-Yellow River area and reduced rainfall over North China in the future,while rainfall over the lower reaches of the Yangtze River basin is not modified significantly.Uncertainties exist in the present study are also discussed.  相似文献   

Greenland Ice Sheet Elevation Change in Winter and Influence of Atmospheric Teleconnections in the Northern Hemisphere          下载免费PDF全文

CHEN Lin-Ling  Ola M. JOHANNESSEN  Kirill KHVOROSTOVSKY  WANG Hui-Jun 《大气和海洋科学快报》2009,2(6):376-380

The relationship between the variability of the surface elevation of the Greenland Ice Sheet （GIS） in winter and sea level pressure is identified through analysis of data from satellite-borne radar altimeters, together with meteorological data fields during 1993-2005. We found that both the North Pacific Oscillation （NPO） and the North Atlantic Oscillation （NAO）, the two major teleconnection patterns of the atmospheric surface pressure fields in the Northern Hemisphere, significantly influence the GIS winter elevation change. Further, it is suggested that the NPO may affect the GIS accumulation by influencing the NAO, particularly by changing the intensity and location of the Icelandic Low.  相似文献   

黔东南大雾气候特征   总被引：7，自引：2，他引：5  

龙先菊  梁平  田菊萍  杨再禹  谢俊英 《气象科技》2010,38(3):321-324

利用1961~2007年黔东南州16个地面气象观测站逐日大雾日数资料,对黔东南州大雾日数的日、年、季分布特点、长期变化趋势、年代际的变化特征等进行分析。结果表明:20世纪60年代平均雾日最多,80年代最少,进入21世纪后具有逐渐增多的趋势;以秋季雾日最多,冬季次之,春季最少;以11月为最多,2月为最少。并且大雾日数有准40年的周期,在大雾多发期存在着准5年的周期性。大雾主要分布在黔东南州的中部,东南部和西北部相对较少。  相似文献   

Analysis of the projected regional sea-ice changes in the Southern Ocean during the twenty-first century   总被引：2，自引：1，他引：1  

W. Lefebvre  H. Goosse 《Climate Dynamics》2008,30(1):59-76

Using the set of simulations performed with atmosphere-ocean general circulation models (AOGCMs) for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4), the projected regional distribution of sea ice for the twenty-first century has been investigated. Averaged over all those model simulations, the current climate is reasonably well reproduced. However, this averaging procedure hides the errors from individual models. Over the twentieth century, the multimodel average simulates a larger sea-ice concentration decrease around the Antarctic Peninsula compared to other regions, which is in qualitative agreement with observations. This is likely related to the positive trend in the Southern Annular Mode (SAM) index over the twentieth century, in both observations and in the multimodel average. Despite the simulated positive future trend in SAM, such a regional feature around the Antarctic Peninsula is absent in the projected sea-ice change for the end of the twenty-first century. The maximum decrease is indeed located over the central Weddell Sea and the Amundsen–Bellingshausen Seas. In most models, changes in the oceanic currents could play a role in the regional distribution of the sea ice, especially in the Ross Sea, where stronger southward currents could be responsible for a smaller sea-ice decrease during the twenty-first century. Finally, changes in the mixed layer depth can be found in some models, inducing locally strong changes in the sea-ice concentration.

W. LefebvreEmail:

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