基于航空联系的中国城市网络格局演变分析   总被引：1，自引：1，他引：0  

张婷婷  陈瑛  王孟林 《世界地理研究》2022,31(1):166-176

运用2000、2005、2010、2017年全国民航机场及航线客流的截面数据（不含港澳台地区）,结合复杂网络、GIS与地理探测器方法,刻画了21世纪以来我国航空联系网络所反映的城市网络格局,并分析其演变过程及影响因素。结果表明：中国目前形成了以上海、北京、广州、成都为一级核心城市,多层次、多中心的网络格局,并由“三中心”逐渐演变为“四中心”结构;中心城市分布具有明显的东西差异,呈现“三足鼎立、西部突出、中部薄弱”态势;全国城市网络具有无标度、小世界特征及较强的集聚性,中心城市在2005年前向东南沿海集聚,而后向中西部地区扩散,集聚性有所降低;中国城市网络格局的演变由政策支持、旅游发展水平、经济基础、产业结构等多因素共同驱动。  相似文献   

Tankering strategies for evading emissions trading in aviation     

MARTIN CAMES 《Climate Policy》2013,13(2):104-120

Which actors in the aviation sector ought to be obliged to participate in emissions trading? The European Commission opted for the aircraft operator in their proposal for a Directive. A major drawback is that non-EU aircraft operators might legally challenge their inclusion in this scheme and, if the challenge was successful, discrimination between EU and non- EU operators would undermine the scheme. An alternative would be to place an obligation on fuel suppliers to prove possession of allowances, thus avoiding discrimination. However, emissions trading can be evaded to some extent by increased refuelling beyond EU boundaries (tankering). Typical city pairs were used to analyse the conditions under which such tankering strategies are economically attractive. The analysis shows that the attractiveness of tankering depends substantially on the relationship between fuel prices and allowance prices. If the price relation as of March 2006 is taken as a basis, tankering would be attractive within a radius of up to 4,000 km especially on southbound and eastward routes. Emissions trading could, under unfavourable conditions, be evaded for up to 20% of the total fuel consumption in aviation with the help of tankering. Although this value is only a theoretical upper limit, more than 10% of fuel consumption could be affected by tankering.  相似文献   

探空气球三维数据采集器的研制     

樊昌元  王保强  文斌 《成都信息工程学院学报》2003,18(4):349-352

主要介绍民航监控系统中的探空气球三维(方位、俯仰、斜距)数据自动采集器的软硬件设计及实现。该采集器的主要功能有：接收探空气球三维编码器数据并处理、换算、显示；接收和显示来自PC机的时间信息；根据PC机不同指令，上传相应时刻的三维数据到计算机。计算机通过MODEM将相应三维数据传到民航空管中心。其中，在显示电路中，提出并使用了一种新的消隐方法，克服了传统静态扫描显示的闪烁现象；在软件上，针对数据的具体特点，提出了化乘除为加减，利用移位、按位补偿处理算法，明显提高效率，保证了信号处理的实时性。  相似文献   

BOOK REVIEWS     

《The Professional geographer》1986,38(3):295-316

Book Reviewed in this article: Marine Resources of Kuwait: Their Role in the Development of Non-oil Resources . Fatimah H. Y. al -Abdul -Razzak Recollections of a Revolution: Geography as Spatial Science . Mark Billinge , Derek Gregory and Ron Martin Entre l'Eden et l'Utopie . Luc Bureau Developments in Political Geography . M. A. Busteed The Elements of Graphing Data . William S. Cleveland Rural Resource Management . Paul J. Cloke and Chris C. Park Third World Atlas . Ben Crow and Alan Thomas Exploitation, Conservation, Preservation: A Geographic Perspective on Natural Resource Use . Susan L. Cutter , Hilary Lambert Renwick, and William H. Renwick . Wine Regions of the Southern Hemisphere . Harm Jan de Blij Regional Development: Problems and Policies in Eastern and Western Europe . George Demko The Geographer at Work . Peter R. Gould Change in the Amazon Basin . John Hemming Geography Since the Second World War . R. J. Johnston and P. Claval Urbanization in China: Town and Countryside in a Developing Economy 1949–2000 A.D. , R. J. R. Kirkby Transport and Communications for Pacific Microstates: Issues in Organisation and Management . Christopher C. Kissling Fluvial Forms and Processes . David Knighton The Urban Millennium . Josef W. Konvitz Technological Transition in Cartography . Mark Stephen Monmonier Field Guide to Soils and the Environment: Applications of Soil Surveys . Gerald W. Olson Northern Australia: The Arenas of Life and Ecosystems on Half a Continent . Don Parkes A Killing Rain: The Global Threat of Acid Rain . Thomas Pawlick From the Family Farm to Agribusiness: The Irrigation Crusade in California and the West, 1850–1931 . Donald J. Pisani Hybrid Maize Diffusion in Kenya . Franz -Michael Rundquist Warning and Response to the Mount St. Helens Eruption . Thomas F. Saarinen and James L. Sell Coastal Geomorphology in Australia . B. G. Thom Tropical Rain Forests of the Far East , 2nd ed . T. C. Whitmore The Dark Side of the Earth . Robert Muir Wood Categorical Data Analysis for Geographers and Environmental Scientists , Neil Wrigley  相似文献   

浅析地理信息系统课程在土木工程专业开设的必要性     

王雪平  周凤玺  张飞 《东北测绘》2012,(8):235-237

介绍了地理信息系统在土木工程专业的广泛应用,论证了土木工程专业开设地理信息系统课程的必要性,并提出了兰州理工大学土木工程专业GIS人才培养途径和地理信息系统课程在土木工程专业开设的初步设想。  相似文献   

全球定位系统的新进展(讲座) 第1讲 导航电文结构的变化和参数的精化——从导航电文的变化看GPS的进展     

李征航  屈小川 《测绘信息与工程》2012,37(1):49-54

介绍了GPS现代化实施后调制在L2C码和L5码上的导航电文CNAV总体结构的变化情况,并对CNAV中部分参数的精化和扩充以及卫星历书的细化部分进行了详细阐述和分析。  相似文献   

基于地缘政治学视角的缅甸内战与毒品经济相互关系解析     

闫晓燕  武友德  曹洪华 《世界地理研究》2021,30(4):721-731

中国西南地区面临着因缅甸内战和毒品经济产生的跨国影响而形成的恶劣的地缘政治环境。通过文本分析法,本文聚焦缅甸内战和毒品经济,在分析缅甸内战历史和现实致因、缅甸毒品经济起源与发展的基础上,从地缘政治学视角,揭示了缅甸内战与毒品经济之间的相互关联。本文试图回答的问题是：缅甸内战状态下的毒品经济为何在缅甸蔓延？毒品经济又如何加深缅甸内战并阻碍内战的终结？缅甸内战与毒品经济相互纠缠,即缅甸内战不是由毒品经济利益所触发,但缅甸内战刺激了鸦片种植和催生了畸形的毒品经济,而毒品经济重塑了缅甸联邦政府与少数民族地方武装等各方利益,从而为缅甸内战解决蒙上了阴影。  相似文献   

乌鲁木齐机场一次寒潮多相态降水过程分析     

王清平  谭艳梅  陈春艳 《气象与环境科学》2018,41(3):109-116

利用常规观测资料及新疆区域自动站、乌鲁木齐风廓线雷达、多普勒雷达资料,针对2015年2月13日发生在乌鲁木齐地区的一次雨雪天气过程,从大气背景环境、风温垂直结构、冷暖平流及雨、雪相态转换成因等方面进行分析。结果表明:此次寒潮降水天气的大尺度环流背景是中亚地区高空脊向极区发展,脊顶北风引导极地冷空气南下,在西西伯利亚地区发展成大槽。大槽东移进入新疆地区后,槽后冷空气与北上的西南暖湿气流在天山山区汇合造成此次寒潮降水天气。乌鲁木齐机场出现雪转雨再转雪等相态转换,是由于先受冷平流控制,随着地面冷锋前部暖平流临近,低空暖层厚度加大,降雪粒子在降落过程中融化为雨滴,地面降水相态转为雨夹雪和雨,冷锋系统进入后,再次处于冷平流控制下,降水相态再由雨转为雪。风廓线雷达风场资料的分析结果表明,空中冷暖平流的性质和转换与降水相态变化有较好的对应关系;风廓线垂直速度显示,降雪粒子与雨滴粒子相比,垂直速度较小且雨滴粒子主要集中在1000 m以下。利用多普勒雷达产品分析地面冷锋的移动、空中冷暖平流的变化,有助于对降水相态变化的预报。  相似文献   

京津冀地区民用机场交通可达性空间特征分析   总被引：3，自引：0，他引：3  

李亚飞  刘高换  黄翀  顾秋丽  任斐鹏 《世界地理研究》2016,(6):57-65

为了定量研究京津冀地区民用机场交通可达性的空间特征,基于京津冀地区公路网数据、铁路网数据和城市地铁网数据,在总结前人研究的基础上,运用Arc GIS的空间分析模块,进行成本距离分析,生成京津冀地区民用机场可达性空间分布图并进行深入分析。结果表明,京津冀机场可达性呈现南高北低、东高西低、中间地区强于边缘地区的态势,其中东部机场可达性最好,北部机场可达性最差,机场时间可达性集中在1.5h-6h时段,约占整个区域的51.1%,京津冀地区机场可达性整体较差;按照本研究定义的有效服务面积,该地区机场有效服务面积分为三个梯队,第一梯队为正定机场、首都国际机场和滨海国际机场;第二梯队为邯郸机场、三女河机场;第三梯队为宁远机场和山海关机场。从该地区机场可达性时段来看,在0-1.5h范围内,首都国际机场的服务面积最大,约占该范围面积25.23%;在1.5-3h和3-4.5h范围内,正定机场的服务面积最大,约占23.5%和21.9%。从研究结果来看,京津冀地区民用机场发展不平衡,需要改善京津冀地区的机场布局,在北部和西部增加机场,扩展有效服务面积;其次着力改善机场所在区域的交通网络建设,扩大现有机场的有效服务区域;最后,明确京津冀区域现有和新建民用机场的功能定位,大力发展区域枢纽机场,提高航空服务资源使用效率。  相似文献   

Compensation of time‐delay for control of civil engineering structures     

A. K. Agrawal  J. N. Yang 《地震工程与结构动力学》2000,29(1):37-62

Time‐delay is an important issue in structural control. Applications of unsynchronized control forces due to time‐delay may result in a degradation of the control performance and it may even render the controlled structures to be unstable. In this paper, a state‐of‐the‐art review for available methods of time‐delay compensation is presented. Then, five methods for the compensation of fixed time‐delay are presented and investigated for active control of civil engineering structures. These include the recursive response method, state‐augmented compensation method, controllability based stabilization method, the Smith predictor method and the Pade approximation method, all are applicable to any control algorithm to be used for controlled design. Numerical simulations have been conducted for MDOF building models equipped with an active control system to demonstrate the stability and control performance of these time‐delay compensation methods. Finally, the stability and performance of the phase shift method, that is well‐known in civil engineering applications, have also been critically evaluated through numerical simulations. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献