Economic viability of Asia-Europe container transport through Arctic routes based on Arctic sea ice          下载免费PDF全文

Luo Qiaoyun  Liu Wei  Shou Jianmin 《极地研究》1988,31(4):447

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An organizational model and border port hinterlands for the China-Europe Railway Express   总被引：3，自引：0，他引：3  

Jiaoe Wang  Jingjuan Jiao  Li Ma 《地理学报(英文版)》2018,28(9):1275-1287

Facilities connectivity is a priority area for implementing the Belt and Road Initiative (BRI). The “China-Europe Railway Express” (CER Express) mode of transport organization links China with Europe by fast-track cargo rail. A major instance of facilities connectivity related to this project is an important practical and symbolic instance of BRI transport cooperation. The strategic significance of the CER Express and a number of operational issues are outlined, as are the implications of limited market potential for costs and competitiveness. A “hub-and-spoke” organizational model that can generate scale economies and reduce costs is proposed. To examine the establishment of an organizational model of this kind, the economic hinterlands of Alashankou, Erenhot, and Manzhouli are identified under high-, mediumand low-cost scenarios using an analytical methodology that determines distance and economic costs, and a number of transport hubs (that include Harbin, Zhengzhou, and Lanzhou) are identified. The results found that the cost of the routes from 314 Chinese cities to Moscow is the lowest via Manzhouli in the high- and medium-cost scenarios, but the routes change via Erenhot in the low-cost scenario. A number of policy recommendations should follow up.  相似文献   

南极航线和航区环境概述     

王殿昌  施国强 《海洋预报》1994,11(4):39-46

本文汇集了我国南极科学考察前十年（１９８４－１９９３年）的南极考察航线，根据航区和任务，对南极航线进行了分类：对各航区中影响航行的海洋环境状况－诸如低纬地区的热带气旋，中纬地区的温带气旋和高纬地区的绕极气旋等主要灾害性天气系统的生成源地，移动路么荼了介绍；文中还着得活冰的增，减期和浮冰边缘线进行了描述。以求达到对过去十年南极考察航线作出比较客观的评价。  相似文献   

Differences in trophodynamics of commercially important fish between artificial waterways and natural coastal wetlands     

Rod M. Connolly 《Estuarine, Coastal and Shelf Science》2003,58(4):929-936

Extensive artificial waterways have replaced natural wetlands and created new estuarine habitats on the southern Queensland coast, Australia. Economically important fish species found in adjacent natural wetlands of mangrove, saltmarsh and seagrass also occur in the artificial waterways. Stable isotope analyses (δ¹³C, δ¹⁵N) were used to test whether the relative importance of basal sources of energy varied for foodwebs found in artificial (canals and tidal lakes) and natural waterways. None of the fish species differed in their isotope values between artificial waterways. In contrast, isotopic signatures of snub-nosed garfish (Arrhamphus sclerolepis; Hemiramphidae) varied greatly between natural and artificial waterways, having highly enriched δ¹³C values (−10.5‰) in natural wetlands, demonstrating reliance on seagrass (−11.4‰), and significantly less enriched values (−19.0‰) in artificial waterways, consistent with either local algal sources (−19.8 to −20.4‰) or a mixture of seagrass and other less enriched autotrophs from adjacent natural wetlands. Isotopic signatures of sand whiting (Sillago ciliata; Sillaginidae) were also significantly more enriched in natural (−18.2‰) than artificial (−21.0‰) habitats, but means were not far enough apart to distinguish between different sources of nutrition. δ¹³C values of yellowfin bream (Acanthopagrus australis; Sparidae) did not differ between artificial and natural habitats (about −20‰ in both). δ¹⁵N values of fish varied among habitats only for A. sclerolepis, which in artificial waterways had values enriched by 2‰ over those in natural waterways. This was consistent with a shift from seagrass (relatively depleted δ¹⁵N) as a source in natural habitat to algal sources (relatively enriched δ¹⁵N) in artificial habitats. This study provides some of the first evidence that at least some fish species rely on different autotrophs in artificial waterways than in adjacent natural wetlands.  相似文献   

山地小城市避震疏散通道通行能力评估及选择研究——以昆明东川城区为例          下载免费PDF全文

马程伟  王培茗  张堃 《地震工程学报》2021,43(5):1112-1122

安全快速的避震疏散通道是新时代背景下提高城市抗灾韧性水平的基础保障,灾时充分发挥避震疏散通道的可靠性和时效性将减轻城市人员伤亡。选取山地小城市昆明东川城区为研究区域,通过系统分析避震疏散通道影响因素,对灾后避震疏散通道的通行能力进行评估,基于ArcGIS建立人口集聚点与避震疏散场所（OD）的归属关系,并在此基础上通过遗传算法进行多条避震疏散通道选择研究,为城市抗震防灾规划提供参考。结果表明：东川城区震后不满足疏散要求的通道主要为城市周边的乡村内部道路及部分老城区道路;避震疏散场所存在服务盲区,新城部分小区缺乏疏散通道与避震疏散场所相连接;部分选择的路径虽满足灾时避震疏散要求,但耗时较长,灾时应优先考虑OD之间的最短路径。  相似文献   

泥石流排导槽研究进展及发展方向     

高全  陈晓清  赵万玉 《中国地质灾害与防治学报》2010,21(2):1-7

泥石流是我国最常见的地质灾害之一,在5.12汶川地震后表现得尤为突出。排导槽作为一种结构简单、经济适用的防护措施在泥石流的防治工程中发挥了重要作用。本文简要阐述了泥石流排导槽的发展历程,重点分析比较全衬砌槽和软基消能型槽的结构特点、排导原理、优缺点及适用范围,其中全衬砌槽束水冲砂的特点增加泥石流的排泄,减少淤积,适于下游有广阔停淤区域或主河有足够输移能力的泥石流;而软基消能槽设置贯穿型横向潜槛,增大摩擦,降低流速,适于下游有城镇、铁路、工厂等重要基础设施的泥石流;分别从横纵断面优化、材料选择等角度总结了排导槽的研究进展:初步界定排导槽合理纵比降为3°～10°;横断面上对矩/梯形、圆形、V形等几种主要槽型水力条件进行分析比较,得出圆形断面最优;尝试运用高强混凝土等新型材料或结构增加排导槽的抗磨强度,延长其使用年限;综合考虑泥石流地质地貌背景、水文条件、施工难易程度、经济与否等多方面因素,选择最合适的排导工程;指出随着各项土木工程中生态需求的日益增长,今后研究工作中应加强模型试验,尤其是交错齿槛等生态型泥石流排导槽的研究,进一步完善泥石流排导槽的优化设计体系。  相似文献   

稀性泥石流对排导槽的冲磨破坏机理   总被引：5，自引：1，他引：5  

周富春  黄本生  杨钢  陈洪凯 《山地学报》2001,19(5):470-473

针对稀性泥石流特点，从垂直于排导槽边壁方向和平行于排导槽边壁方向对排导槽的受力情况进行比较深入的分析，导出了多个公式，为设计排导槽提供了理论依据。  相似文献   

Effect of spatial pattern on nutrient reduction in the Liaohe Delta     

LI Xiu-zhen  XIAO Du-ning  HU Yuan-man  WANG Xian-li 《地理学报》2001,11(3):336-349

The effect of spatial pattern on the nutrient reduction is investigated based on the spatial simulation model developed for the study area of the Liaohe Delta, China. Four scenarios are designed to test the effect of different landscape components on the nutrient reduction in the reed marsh: Canal density, reed area size, reed area shrinking pattern, and pumping station position. Based on a spatial model designed for the study area, the nutrient reduction in each case of these scenarios is simulated. The results indicate that each factor brings less than 10% change in the total nutrient reduction rate. More canals will not help much to improve nutrient reduction. Smaller areas are more efficient than larger ones. The shrinkage pattern is better than others in keeping a higher nutrient reduction rate. It is also more efficient to keep the pumping station near the border of the area to be irrigated. These conclusions provide theoretical supports to strategy makers for local land use planning, and contribute to the understanding of the relationship between landscape patterns and functions.  相似文献   

泥石流多发区引水工程渠首泥砂灾害试验研究——以云南东川团结渠首为例     

游勇  程尊兰 《山地学报》2001,(6)

本文以云南东川团结渠首为研究对象 ,对泥石流多发区引水工程泥沙灾害形成条件进行分析 ,通过渠首型试验研究 ,并结合野外实地踏勘资料综合分析 ,提出了渠首泥沙灾害防治的工程方案和技术措施 ,为工程设计提供可靠的基本参数和依据  相似文献   

Effect of spatial pattern on nutrient reduction in the Liaohe Delta     

LI Xiu-zhen  XIAO Du-ning  HU Yuan-man  WANG Xian-li 《地理学报(英文版)》2001,11(3):336-349

Landscape pattern analysis has been a major topic in landscape ecology[1-4]. Many quantitative methods have also been designed to describe the pattern, in order to get an overall idea of how the landscape is structured, and what is the effect of different patterns on large scale ecological processes[5-11]. So far this kind of research has mainly focused on habitat analysis, or site selection of wild animals, in the scope of nature conservation[12-13]. But few pattern analyses have been made on…  相似文献