地图见证武汉十年发展历程

立足武汉现状,从城市风貌、城市建设、城市生活等方面用地图和文字进行描述,通过面、线、点将武汉的十年变化在空间上进行定位和说明,以“数字武汉”的形式勾绘出武汉的每一个发展步伐,见证“魅力武汉”的实质和内涵,以最直观的方式展示了武汉的十年变迁。     

苏南、浙北地区民宿空间分布特征及其影响因素

选取社会经济、配套产业发达且相近的苏南、浙北地区作为研究区域,基于百度地图API中的地点检索服务获取民宿点地理信息,结合空间分析方法与地理探测器探究两地民宿空间分布特征与影响因素。结果表明：1）两大地区民宿均呈显著集聚状态,分布在地势低平且水系发达区域,依托高禀赋旅游资源和交通干线集聚。2）在两地区别上,苏南民宿表现出集聚程度上的市域差异,浙北则分布相对均衡且集聚范围较广;空间集聚态势差异性显著,前者呈“四核集聚,次级中心团状布局”,后者表现出“西东中梯度格局”。3）消费能力、客源市场与通达程度是影响两地民宿分布的重要共性因子,两两因子间的交互作用增强了对民宿空间异质性的解释力。4）浙北民宿受外部客观因素的影响程度较弱,水系环境与景区依赖是两大地区间的区别因子。     

短时车流量组合预测模型

随着道路车量不断增多,由交通异常事件造成的非正常拥堵情况严重影响了出行者的出行效率和路网的整体运行水平.因此,需要准确及时地检测出非正常拥堵情况,通过诱导、疏通等方式改善拥堵状况.对车流量的准确预测是检测非正常拥堵的有效方法.根据交通流量的不确定性和非线性的特点,将改进的BP神经网络模型和ARIMA模型进行组合,建立组合预测模型.实验结果表明,组合模型的预测结果比单个模型的预测结果理想,且达到较高的预测精度.     

Comparison of PM2.5 and CO2 Concentrations in Large Cities of China during the COVID-19 Lockdown

Estimating the impacts on PM_2.5pollution and CO₂emissions by human activities in different urban regions is important for developing efficient policies.In early 2020,China implemented a lockdown policy to contain the spread of COVID-19,resulting in a significant reduction of human activities.This event presents a convenient opportunity to study the impact of human activities in the transportation and industrial sectors on air pollution.Here,we investigate the variations in air quality attributed to the COVID-19 lockdown policy in the megacities of China by combining in-situ environmental and meteorological datasets,the Suomi-NPP/VIIRS and the CO₂emissions from the Carbon Monitor project.Our study shows that PM_2.5concentrations in the spring of 2020 decreased by 41.87%in the Yangtze River Delta(YRD)and 43.30%in the Pearl River Delta(PRD),respectively,owing to the significant shutdown of traffic and manufacturing industries.However,PM_2.5concentrations in the Beijing-Tianjin-Hebei(BTH)region only decreased by 2.01%because the energy and steel industries were not fully paused.In addition,unfavorable weather conditions contributed to further increases in the PM_2.5concentration.Furthermore,CO₂concentrations were not significantly affected in China during the short-term emission reduction,despite a 19.52%reduction in CO₂emissions compared to the same period in 2019.Our results suggest that concerted efforts from different emission sectors and effective long-term emission reduction strategies are necessary to control air pollution and CO₂emissions.     

川藏交通干线帕隆藏布段冰碛物特性研究进展

作为冰川运动的遗迹,冰碛物由于其宽级配、大孔隙、非均质、渗透性等特点,成为川藏铁路和高速公路帕隆藏布路段规划选线中的一类特殊岩土体,并与藏东南地区的冰川型地质灾害具有关联,使得帕隆藏布流域地质灾害的成因机理及防治研究愈发复杂。本文通过分析近年来国内外学者围绕冰碛物物性特征取得的研究成果,结合实地调查和室内外测试结果,归纳了冰碛物的分布特征、沉积构造、物理性质和工程力学特性,梳理了冰碛物的物理力学研究进展,凝练了帕隆藏布流域冰碛物研究中的3个关键问题,针对性地提出下一步研究思路,旨在为后续的冰碛物研究和川藏交通干线规划与建设管理提供参数依据。     

云南漾濞6.4级地震交通系统震害调查分析

2021年5月21日21时48分34秒,云南省大理州漾濞县发生6.4级地震,中国地震局组织专家迅速进入灾区开展烈度评定和损失评估等现场应急工作。为加深业内同行对交通系统地震破坏的认识和理解,本文主要针对此次地震中交通系统的破坏情况进行宏观性描述,展现地震中交通系统的地震破坏现象,对道路和桥梁的主要震害特征进行总结,对典型震害的形成原因进行了探讨。最后,结合此次地震的破坏特点,为我国交通系统的抗震策略提出思考与建议。     

An optimum vehicular path algorithm for traffic network based on hierarchical spatial reasoning

Human beings’ intellection is the characteristic of a distinct hierarchy and can be taken to construct a heuristic in the shortest path algorithms. It is detailed in this paper how to utilize the hierarchical reasoning on the basis of greedy and directional strategy to establish a spatial heuristic, so as to improve running efficiency and suitability of shortest path algorithm for traffic network. The authors divide urban traffic network into three hierarchies and set forward a new node hierarchy division rule to avoid the unreliable solution of shortest path. It is argued that the shortest path, no matter distance shortest or time shortest, is usually not the favorite of drivers in practice. Some factors difficult to expect or quantify influence the drivers’ choice greatly. It makes the drivers prefer choosing a less shortest, but more reliable or flexible path to travel on. The presented optimum path algorithm, in addition to the improvement of the running efficiency of shortest path algorithms up to several times, reduces the emergence of those factors, conforms to the intellection characteristic of human beings, and is more easily accepted by drivers. Moreover, it does not require the completeness of networks in the lowest hierachy and the applicability and fault tolerance of the algorithm have improved. The experiment result shows the advantages of the presented algorithm. The authors argued that the algorithm has great potential application for navigation systems of large-scale traffic networks.     

Follow the road: historical GIS for evaluating the development of routes in the Negev region during the twentieth century

ABSTRACT

At the beginning of the twentieth century, a British mapping team led by Captain S. F. Newcombe surveyed and mapped the Negev region, Sinai, and western Jordan. The map was mainly produced for military use. Consequently, it included a network of branched routes, water supplies and facilities, and topographic contours. This study used this map to examine the development of routes in the Negev region between the beginning of and until the end of the twentieth century. First, the individual sheets comprising the study area were pieced together and the accuracy of the map was evaluated. The accuracy found on the Newcombe map was 0.76 mm on the map scale, equivalent to 100.3 m. Route development during the twentieth century was then evaluated by comparing the routes digitized from the Newcombe map to digitized routes on a late twentieth-century map. The results do not reveal tremendous changes in path, shape, or number of routes. Instead, they merely indicate the natural development in their quality. This Historical GIS-based approach provided a useful technique for analyzing and comparing the line segments extracted from historical and modern maps. The implemented approach may also serve other geographical or historical studies aiming to examine the development of branched networks throughout history.     

环境激励下大跨悬索桥实测损伤预警指标的变异性

基于小波包分析技术从悬索桥的加速度振动响应中提取出小波包能量比,进而定量地分析了由环境激励所引起的实测小波包能量比的变异性。首先,采用多样本平均技术消除了由识别算法所带来的小波包能量比的固有随机性,得到了小波包能量比的日平均值;其次,通过建立季节相关性模型得到了温度对小波包能量比影响的定量评价;最后,分别建立交通荷载和风与小波包能量比的相关性模型,并定量评价了交通荷载和风对小波包能量比的影响。分析结果表明,温度和固有随机性是小波包能量比变异性的最主要来源,而交通荷栽和风所引起的变异性较小。由于温度和小波包能量比的季节相关性模型可以有效地消除温度和固有随机性对小波包能量比的影响,因此当季节相关性模型偏离这种正常状态的模型时,就可以对悬索桥做出损伤预警。     

International Telephone Calls: Global and Regional Patterns

This study examines patterns in international telephone communications, documenting a close relationship between international call volume aggregated by nation and indicators of global connectivity including volume of international trade, tourism and migration. In addition, the analysis documents the existence of a set of national "communities" of callers. The clear orientation of large portions of the world to former colonial powers (e.g., West Africa and North Africa to France), and the separation of the Muslim Middle East and the Chinese-speaking nations of East and Southeast Asia from other calling communities suggest the importance of continuing historic and cultural influences on information flows.