基于百度贴吧数据的长江中游城市群城市网络联系分析

以百度城市吧主题帖的累积截面数据为基础数据,采用优势流分析法等,定量分析流空间视角下长江中游城市群城市网络联系特征。结果表明：① 长江中游城市群城市贴吧网络联系密度为77.74%,大部分城市间存在比较普遍的网络联系。② 长江中游城市群31个城市可划分为全域、普遍、较多、一般、较少伙伴型城市等5种类型,环鄱阳湖城市群缺少全域和较多伙伴型城市,城市网络联系不如武汉城市圈和环长株潭城市群活跃。③ 长江中游城市群尺度上尚未形成绝对意义上的主导型和次级主导型城市,仅有武汉与长沙表现出了主导型城市的雏形,整体城市网络联系层级结构不是十分明晰。④ 按照主导性、控制力的强弱,长江中游城市群已基本呈现“一主两副三中心五节点”金字塔型的城市网络联系格局,武汉为大区中心城市,长沙和南昌为大区副中心城市,株洲、九江、宜昌可认为是各子城市群的中心城市,岳阳、黄石、襄阳、衡阳和景德镇应定性为各子城市群的控制节点城市。     

城市公共自行车使用与建成环境的关系研究——以南京市桥北片区为例

公共自行车作为一种绿色低碳的交通出行方式,在国内外许多城市得到了快速发展。目前国内公共自行车相关研究多以使用特征分析为主,而与建成环境关系的研究较少。采用运营大数据与网络开放大数据相结合的方法,以南京市桥北区为案例,研究公共自行车站点使用特征及建成环境对其的影响。研究结果表明：① 公共自行车的使用存在明显的时空间差异;② 使用主要受站点300 m范围内日常服务设施网点密度、基础设施及公共交通条件等建成环境因子影响;③ 建成环境对不同时段使用的影响存在较大差异。研究结果可为片区站点的优化布局与管理建设,以及无桩型共享单车的投放与运营管理提供科学的参考依据。     

Geology and K-Ar dating of the Tuxtla Volcanic Field,Veracruz, Mexico

The Tuxtla Volcanic Field (TVF) is located on the coast of the Gulf of Mexico in the southern part of the state of Veracruz, Mexico. Volcanism began about 7 my ago, in the Late Miocene, and continued to recent times with historical eruptions in ad 1664 and 1793. The oldest rocks occur as highly eroded remnants of lava flows in the area surrounding the historically active cone of San Martín Tuxtla. Between about 3 and 1 my ago, four large composite volcanoes were built in the eastern part of the area. Rocks from these structures are hydrothermally altered and covered with lateritic soils, and their northern slopes show extensive erosional dissection that has widened preexisting craters to form erosional calderas. The eastern volcanoes are composed of alkali basalts, hawaiites, mugearites, and benmoreites, with less common calc-alkaline basaltic andesites and andesites. In the western part of the area, San Martín Tuxtla Volcano and its over 250 satellite cinder cones and maars produced about 120 km³ of lava over the last 0.8 my. A ridge of flank cinder cones blocked drainage to the north to form Laguna Catemaco. Lavas erupted from San Martín and its flank vents are restricted to compositions between basanite and alkali basalt. The alignment of major volcanoes and flank vents along a N55°W trend suggests an extensional stress field in the crust with a minimum compressional stress orientation of N35° E. In total, about 800 km³ of lava has been erupted in the TVF in the last 7 my. This gives a magma output rate of about 0.1 km³/1000 year, a value smaller than most composite cones, but similar to cinder cone fields that occur in central Mexico. Individual eruptions over the last 5000 years had volumes on the order of 0.1km³, with average recurrence intervals of 600 years. The alkaline compositions of the TVF lavas contrast markedly with the calc-alkaline compositions erupted in the subduction-related Mexican Volcanic Belt to the west, leading previous workers to suggest that the TVF is not related to subduction. Trace-element signatures of TVF lavas indicate, however, that they are probably related to subduction. We suggest that the alkaline character of the TVF lavas is the result of low degrees of melting of a mantle source coupled with a stress regime that allows these small-volume melts to reach the surface in the TVF.     

嘉峪关市土地生态安全动态评价及影响因素分析

土地生态安全评价对管控区域生态风险和保障生态安全具有重要意义.基于"数量安全-质量安全-结构安全-保障安全"模型构建指标评价体系,采用相对熵方法进行组合赋权,揭示嘉峪关市土地生态安全的动态变化过程,并运用因子分析法探讨其主要影响因素.结果 表明:(1)2000—2017年,嘉峪关市土地生态安全综合指数呈上升趋势,由20...     

基于集群视角的煤炭城市产业转型研究——以安徽淮南市为例

20世纪90年代以来,煤炭城市发展出现了经济衰退、竞争力下降等一系列问题,如何实现煤炭城市的产业转型是社会关注的热点。文章分析了煤炭城市产业转型中的集群效应,认为立足于传统产业优势,发展煤炭产业集群是煤炭城市实现依托式产业转型的有效途径。在此基础上,探讨了淮南市煤炭产业群发展现状及特征,提出了煤炭产业群的发展思路。     

产业集群与传统制造业竞争力提升——以天津自行车产业为例

与技术、资本相比,生产组织形式的选择和创新日益成为全球经济条件下企业、产业和区域国际竞争力提升的重要决定因素。对于传统制造业来说,通过集群生产方式构建地方性生产网络对国家或区域制造业的发展和国际竞争力的提升具有十分重要的战略意义。天津自行车产业的发展表现为生产组织方式的创新和演进过程,即、由计划经济时代的“大而全”和“小而全”的高度纵向一体化的生产组织向“专业化＋网络化”的集群式生产组织方式转变,产业竞争力的提升得益于地方生产网络的构建。文章通过这一案例研究,探讨如何利用这次生产组织方式的变革和演进中隐藏的潜在后发优势,提升我国传统制造业的国际竞争力。     

城镇化下河流水质变化及其与景观格局关系分析——以太湖流域苏州市为例

以河流近域景观格局与水环境质量间的关系为研究对象,基于2001年及2010年两期土地利用类型以及7条典型河流的溶解氧、氨氮、高锰酸盐指数、总磷、总氮5项水质指标,分析城镇化下苏州市河流水质与景观格局之间的关系及其变化规律.结果表明:(1)苏州市河流水质状况总体较差,但呈现一定的好转趋势.(2)河流水质受到城镇用地、旱地及水田的综合影响,并表现出尺度效应.其中城镇用地与旱地对河流水质恶化具有明显的作用,水田则反之.2001-2010年城镇用地及水田对水质的影响程度有所减弱,旱地则增强.(3)蔓延度指数、最大面积斑块比例对河流水质呈现负相关,斑块数量、斑块密度、香农均匀度指数、香农多样性指数则与水质呈现正相关.景观格局对于水质的影响在大范围缓冲区更为显著.研究结果可为苏州水环境管理及太湖流域城市空间开发提供一定的参考依据.     

南京市5座中型水库浮游动物群落结构及其与环境因子的关系

于2010年5月—2011年2月,对南京市5座中型湖泊型水库浮游动物群落结构进行每季度一次的调查采样,同时测定总氮、总磷、透明度等理化因子及浮游植物等生物因子.共鉴定到浮游动物17科28属,优势种为盔形溞(Daphnia galeata)、象鼻溞(Bosmina spp.)、汤匙华哲水蚤(Sinocalanus dorrii)、多肢轮虫(Trichocerca spp.)、异尾轮虫(Polyarthra spp.)等.5座水库浮游动物年均密度变化范围为72~1401 ind./L,其中河王水库密度显著大于其他水库,而4个季节间浮游动物密度无显著差异.5座水库浮游动物年均生物量变化范围为102~339μg/L,季节间、水库间浮游动物生物量均无显著性差异.浮游动物群落结构与环境因子的典范对应分析表明,影响5座水库浮游动物群落结构的环境因子主要为营养盐、水温、透明度和浮游植物密度.     

Changes in the plain river system and its hydrological characteristics under urbanization – case study of Suzhou City,China

ABSTRACT

Rapid urbanization in China has severely disturbed the underlying surface and river systems. The stream structure parameters of Suzhou City were analysed to study the evolution and spatial differentiation of a water system undergoing urbanization. The influencing pattern of different urbanization processes on river system structure and hydrological processes was detected by statistical methods and simulation analysis. The results show that urban sprawl is influenced by both the natural environment and the social economy. At different stages of urbanization, the spatial urban expansion and the natural river characteristics influence the evolution of the river network: during rapid urbanization, the decline in surface water ratio and river density is more intense. The decrease of surface water ratio and river density in rapidly urbanized areas was greatest, followed by that in area urbanized in the 1980s, with few changes in the old town. Under high urbanization, river system indicators tend to stabilize. The rivers’ hydrological features were affected by urbanization, with water yield in the study area increasing from 0.81 to 0.95 m³/m² (1991–2015). The same rainfall intensity results in higher flood levels and greater risk of flooding under rapid urbanization.     

基于结构方程模型的城市邻避设施风险可接受度研究——以天长市为例

基于天长市1 250份问卷数据,运用SPSS进行效度及因子分析,确立公众的“风险认知”、“政府信任”、“公众参与”及“补偿措施”作为公众对邻避设施风险认知可接受度的潜变量,通过文献整理,确定原假设。运用AMOS21.0软件建立结构方程模型,检验原假设是否成立;并分析潜变量与“接受度”之间的关系。研究结果显示,“风险感知”对“接受度”影响系数-0.262;其次是“公众参与”,影响系数-0.242。两者均为负向相关影响。“政府信任”及“补偿措施”对“接受度”正向影响。同时,四个潜变量之间存在一定的正向影响。人口学变量中的年龄与受教育水平在一定程度上对“接受度”有影响。通过对天长市调查研究,分析了公众的风险接受度的影响因素,对影响因子进行量化,能够客观的比较其重要性;同时对政府及相关工作者有一定的启示,根据影响因子与“接受度”之间的关系,因地制宜,制定相关的政策与措施,来降低或避免邻避冲突。