Urban tourism is considered a complex system,and multiscale exploration of the organizational patterns of attraction networks has become a topical issue in urban tourism,so exploring the multiscale characteristics and...Urban tourism is considered a complex system,and multiscale exploration of the organizational patterns of attraction networks has become a topical issue in urban tourism,so exploring the multiscale characteristics and connection mechanisms of attraction networks is important for understanding the linkages between attractions and even the future destination planning.This paper uses geotagging data to compare the links between attractions in Beijing,China during four different periods:the pre-Olympic period(2004–2007),the Olympic Games and subsequent‘heat period’(2008–2013),the post-Olympic period(2014–2019),and the COVID-19(Corona Virus Disease 2019)pandemic period(2020–2021).The aim is to better understand the evolution and patterns of attraction networks at different scales in Beijing and to provide insights for tourism planning in the destination.The results show that the macro,meso-,and microscales network characteristics of attraction networks have inherent logical relationships that can explain the commonalities and differences in the development process of tourism networks.The macroscale attraction network degree Matthew effect is significant in the four different periods and exhibits a morphological monocentric structure,suggesting that new entrants are more likely to be associated with attractions that already have high value.The mesoscale links attractions according to the common purpose of tourists,and the results of the community segmentation of the attraction networks in the four different periods suggest that the functional polycentric structure describes their clustering effect,and the weak links between clusters result from attractions bound by incomplete information and distance,and the functional polycentric structure with a generally more efficient network of clusters.The pattern structure at the microscale reveals the topological transformation relationship of the regional collaboration pattern,and the attraction network structure in the four different periods has a very similar importance profile structure suggesting that the attraction network has the same construction rules and evolution mechanism,which aids in understanding the attraction network pattern at both macro and micro scales.Important approaches and practical implications for planners and managers are presented.展开更多
随着电子产品消费量的日益增多,电子废弃物(WEEE)的数量也不断增加,WEEE管理已成为全球关注的热点环境问题。以Web of Science核心数据库和中国知网(CNKI)全文数据库相关文献作为样本,借助Citespace软件对2007-2017年国内外WEEE管理文...随着电子产品消费量的日益增多,电子废弃物(WEEE)的数量也不断增加,WEEE管理已成为全球关注的热点环境问题。以Web of Science核心数据库和中国知网(CNKI)全文数据库相关文献作为样本,借助Citespace软件对2007-2017年国内外WEEE管理文献进行了可视化分析,旨在理清中国与国际WEEE管理的发展脉络、研究热点和前沿趋势。结果表明:(1)国际关于WEEE管理的热度不断增加,研究重点由发达国家逐渐转向发展中国家和地区;(2)WEEE管理的研究方法、研究内容和研究角度日益丰富,生产者责任延伸制度、绿色设计、生命周期评价、逆向物流和工业生态学都成为研究的热点;(3)未来中国WEEE管理研究应注重WEEE管理的立法建设和理论技术创新以及大数据与信息系统在WEEE管理方面的应用。展开更多
临界悬浮转速和搅拌功率是评价搅拌设备的重要指标。本文采用采用多重参考系法(multiple reference frame,M R F)和欧拉多相流模型,对不同的物料在六平直叶圆盘涡轮式桨叶搅拌槽的临界悬浮转速以及搅拌功率进行数值模拟,得到了搅拌槽内...临界悬浮转速和搅拌功率是评价搅拌设备的重要指标。本文采用采用多重参考系法(multiple reference frame,M R F)和欧拉多相流模型,对不同的物料在六平直叶圆盘涡轮式桨叶搅拌槽的临界悬浮转速以及搅拌功率进行数值模拟,得到了搅拌槽内的宏观流场、临界悬浮转速以及搅拌功率等,采用试验值与文献值对数值模拟进行验证。结果表明:对于4挡板的六平直叶圆盘涡轮式桨叶搅拌槽其内部主要由四个循环流构成;增大矿浆浓度会导致局部液相速度降低;并且物料的直径、密度以及含固率的增大将导致搅拌槽的临界悬浮转速以及搅拌功率的增加。展开更多
基金Under the auspices of the National Natural Science Foundation of China(No.41971202)the National Natural Science Foundation of China(No.42201181)the Fundamental research funding targets for central universities(No.2412022QD002)。
文摘Urban tourism is considered a complex system,and multiscale exploration of the organizational patterns of attraction networks has become a topical issue in urban tourism,so exploring the multiscale characteristics and connection mechanisms of attraction networks is important for understanding the linkages between attractions and even the future destination planning.This paper uses geotagging data to compare the links between attractions in Beijing,China during four different periods:the pre-Olympic period(2004–2007),the Olympic Games and subsequent‘heat period’(2008–2013),the post-Olympic period(2014–2019),and the COVID-19(Corona Virus Disease 2019)pandemic period(2020–2021).The aim is to better understand the evolution and patterns of attraction networks at different scales in Beijing and to provide insights for tourism planning in the destination.The results show that the macro,meso-,and microscales network characteristics of attraction networks have inherent logical relationships that can explain the commonalities and differences in the development process of tourism networks.The macroscale attraction network degree Matthew effect is significant in the four different periods and exhibits a morphological monocentric structure,suggesting that new entrants are more likely to be associated with attractions that already have high value.The mesoscale links attractions according to the common purpose of tourists,and the results of the community segmentation of the attraction networks in the four different periods suggest that the functional polycentric structure describes their clustering effect,and the weak links between clusters result from attractions bound by incomplete information and distance,and the functional polycentric structure with a generally more efficient network of clusters.The pattern structure at the microscale reveals the topological transformation relationship of the regional collaboration pattern,and the attraction network structure in the four different periods has a very similar importance profile structure suggesting that the attraction network has the same construction rules and evolution mechanism,which aids in understanding the attraction network pattern at both macro and micro scales.Important approaches and practical implications for planners and managers are presented.
文摘随着电子产品消费量的日益增多,电子废弃物(WEEE)的数量也不断增加,WEEE管理已成为全球关注的热点环境问题。以Web of Science核心数据库和中国知网(CNKI)全文数据库相关文献作为样本,借助Citespace软件对2007-2017年国内外WEEE管理文献进行了可视化分析,旨在理清中国与国际WEEE管理的发展脉络、研究热点和前沿趋势。结果表明:(1)国际关于WEEE管理的热度不断增加,研究重点由发达国家逐渐转向发展中国家和地区;(2)WEEE管理的研究方法、研究内容和研究角度日益丰富,生产者责任延伸制度、绿色设计、生命周期评价、逆向物流和工业生态学都成为研究的热点;(3)未来中国WEEE管理研究应注重WEEE管理的立法建设和理论技术创新以及大数据与信息系统在WEEE管理方面的应用。
文摘临界悬浮转速和搅拌功率是评价搅拌设备的重要指标。本文采用采用多重参考系法(multiple reference frame,M R F)和欧拉多相流模型,对不同的物料在六平直叶圆盘涡轮式桨叶搅拌槽的临界悬浮转速以及搅拌功率进行数值模拟,得到了搅拌槽内的宏观流场、临界悬浮转速以及搅拌功率等,采用试验值与文献值对数值模拟进行验证。结果表明:对于4挡板的六平直叶圆盘涡轮式桨叶搅拌槽其内部主要由四个循环流构成;增大矿浆浓度会导致局部液相速度降低;并且物料的直径、密度以及含固率的增大将导致搅拌槽的临界悬浮转速以及搅拌功率的增加。
