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高速铁路对中国城市人口规模变化的影响 被引量:21
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作者 邓涛涛 闫昱霖 王丹丹 《财贸研究》 CSSCI 北大核心 2019年第11期1-13,共13页
以286个地级及以上城市为研究对象,选取城市常住人口指标衡量城市人口规模,并从人口增速与人口增量两方面探讨高速铁路对中国城市人口规模变化的影响。研究表明:高速铁路开通有助于城市人口增加,然而由于高速铁路开通时间较短,城市人口... 以286个地级及以上城市为研究对象,选取城市常住人口指标衡量城市人口规模,并从人口增速与人口增量两方面探讨高速铁路对中国城市人口规模变化的影响。研究表明:高速铁路开通有助于城市人口增加,然而由于高速铁路开通时间较短,城市人口的增长并不明显;高速铁路对城市人口增量和增速的影响与该城市初始人口规模、是否在五大城市群内、城市产业结构密切相关;高速铁路开通后,大城市的人口增加数量明显大于中小型城市,高速铁路大规模建设将进一步导致人口分布的极化发展;高速铁路的开通有利于五大国家级城市群人口的集聚,第三产业占比高的城市人口增加更多,但对这些城市的人口增长率并没有表现出较显著的作用。 展开更多
关键词 高速铁路 城市人口规模 城市群效应 产业结构效应
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菲律宾地理教育的发展历史及现状
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作者 吴金铭 邓涛涛 《地理教学》 2006年第9期36-38,共3页
地理的概念,经常被说成是“普遍的科学”和“自然与社会科学之母”,从古至今地理经历了一种循环的发展模式。发展和兴旺的时期同停滞和委靡的时期相交替。正如世界上很多国家的地理教育循环发展历程一样,在菲律宾也是如此。
关键词 地理教育 菲律宾 发展历史 社会科学 循环
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两种铝挤压用模具钢的组织与性能研究 被引量:3
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作者 黄志其 陈慧 +3 位作者 邓涛涛 许栩达 陈宜钊 胡权 《材料研究与应用》 CAS 2021年第1期47-50,共4页
为了找到一种简易可行的方法对模具钢材质量进行管控,通过金相组织观察、洛氏硬度试验、断口冲击试验及扫描电子显微分析,对两种铝挤压用模具钢的组织与性能进行了对比研究.结果表明:晶界脆性相和钢材原始组织不均匀是造成钢材韧性差的... 为了找到一种简易可行的方法对模具钢材质量进行管控,通过金相组织观察、洛氏硬度试验、断口冲击试验及扫描电子显微分析,对两种铝挤压用模具钢的组织与性能进行了对比研究.结果表明:晶界脆性相和钢材原始组织不均匀是造成钢材韧性差的主要原因,冲击韧性测试能直观的反映钢材性能,可以作为钢材性能检测的重要指标. 展开更多
关键词 模具钢 洛氏硬度 冲击韧性 组织与性能
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时效状态对Al-5.9Zn-0.8Mg合金压溃性能的影响 被引量:1
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作者 万里 邓涛涛 +1 位作者 刘荣超 王凯 《材料研究与应用》 CAS 2021年第5期525-528,共4页
通过电子万能试验机、透射电镜等,研究了不同时效状态对半连续铸造的Al-5.9Zn-0.8Mg合金压溃性能的影响.结果表明:T4(30 d常温停放)状态试样的抗拉强度接近于T6(T4+120℃/24 h)状态试样的抗拉强度,合金表现出强烈的自然时效效应;T7(T6+... 通过电子万能试验机、透射电镜等,研究了不同时效状态对半连续铸造的Al-5.9Zn-0.8Mg合金压溃性能的影响.结果表明:T4(30 d常温停放)状态试样的抗拉强度接近于T6(T4+120℃/24 h)状态试样的抗拉强度,合金表现出强烈的自然时效效应;T7(T6+170℃/10 h)状态试样抗拉强度低于T6状态试样,但两状态屈服强度接近;各状态试样的断后综合延伸率(A50)数值在15%~16%之间,T4,T6和T7的均匀延伸率(Ag)分别为15.2%,13.1%和8.5%;均匀塑性变形程度最高的T4状态试样在压溃过程中发生脆性开裂,而出现严重颈缩现象的T7状态试样则能在压溃过程中均匀折皱,其压溃性能最优. 展开更多
关键词 AL-ZN-MG合金 时效状态 延伸率 压溃性能
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En-route Sector Complexity Control Strategies in Air Traffic Management 被引量:4
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作者 WANG Hongyong DONG Zhenzhen +1 位作者 DENG Taotao SONG Ziqi 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2021年第6期901-913,共13页
Along with the rapid development of air traffic, the contradiction between conventional air traffic management(ATM)and the increasingly complex air traffic situations is more severe,which essentially reduces the opera... Along with the rapid development of air traffic, the contradiction between conventional air traffic management(ATM)and the increasingly complex air traffic situations is more severe,which essentially reduces the operational efficiency of air transport systems. Thus,objectively measuring the air traffic situation complexity becomes a concern in the field of ATM. Most existing studies focus on air traffic complexity assessment,and rarely on the scientific guidance of complex traffic situations. According to the projected time of aircraft arriving at the target sector boundary,we formulated two control strategies to reduce the air traffic complexity. The strategy of entry time optimization was applied to the controllable flights in the adjacent upstream sectors. In contrast,the strategy of flying dynamic speed optimization was applied to the flights in the target sector. During the process of solving complexity control models,we introduced a physical programming method. We transformed the multi-objective optimization problem involving complexity and delay to single-objective optimization problems by designing different preference function. Actual data validated the two complexity control strategies can eliminate the high-complexity situations in reality. The control strategy based on the entry time optimization was more efficient than that based on the speed dynamic optimization. A basic framework for studying air traffic complexity management was preliminarily established. Our findings will help the implementation of a complexity-based ATM. 展开更多
关键词 air traffic management(ATM) air traffic situation air traffic control complexity-based management traffic complexity
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Airway Network Characteristics Based on Complex Network Model 被引量:2
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作者 WANG Hongyong DENG Taotao +2 位作者 SONG Ziqi WANG Fei ZHAO Yifei 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2020年第2期242-262,共21页
Airway networks are the basic carriers of air traffic.Characterizing airway networks will significantly improve the operating efficiency of aviation.This study is targeted at the airway network composed of 1479 waypoi... Airway networks are the basic carriers of air traffic.Characterizing airway networks will significantly improve the operating efficiency of aviation.This study is targeted at the airway network composed of 1479 waypoints in 2018 of China.Together with spatial structures,traffic flow characteristics,and the dominating traffic flow,four airway network models are constructed from the perspective of complex networks,including physical airway network,airway traffic network,directed airway traffic network,and dominance-based directed airway traffic network.Then the topological characteristics of different networks are statistically analyzed by using typical network measure indices,and the differences of these indices among different networks are investigated.Thereby,composite indices are proposed.Statistical results show that the airway network under the influence of traffic flows exhibits richer heterogeneity and asymmetrical between-node relationship,and the distributions of indices among different networks are significantly different.Comparative analysis of composite indices and traffic flows show that some waypoints yield great results in multiple composite indices and traffic volumes;some waypoints display large results in multiple composite indices but low traffic flows,and other waypoints only perform well in certain composite indices.The importance levels of waypoints are divided,by the K-means method based on degree composite index,betweenness composite index and closeness composite index,into three levels,and the reasonableness of clustering results is validated by the statistical results of traffic flows,airport number,and flight delay. 展开更多
关键词 airway network complex network air traffic management
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