中国“四纵四横”高铁网络可达性综合评估与对比

传统测算可达性的方法较为单一,缺乏多层面、多角度的综合研究和对比分析。基于时间、经济与重心视角利用可达性模型并结合ArcGIS 空间分析手段探究高铁通车前后沿线城市可达性的动态变化;利用综合变异系数、层级分析法和改进的哈夫模型分析高铁可达性空间演变特征及规律,构建高铁可达性评价体系并结合熵权法定量评估各高铁可达综合实力。研究表明：京广、京沪可达综合实力最强,沪昆、杭福深次之,沪汉蓉、哈大、青太再次之,郑西、兰新可达实力最弱;全国高铁可达性强弱变化呈明显地带性规律,东、中部高铁可达性强于东北,东北强于西部,纵向高铁强于横向;经济潜力的增加率明显高于加权平均旅行时间的减少率,可达性重心偏移驱使不同等时圈蔓延交叠;高铁以“核心—核心”逐步向“核心—网络”空间链接模式过渡,产生上海、北京、广州、深圳4 个高铁“国家服务中心”,天津、武汉、重庆等6 个“大区域服务中心”,形成“多中心”高铁服务格局以及日益庞大而复杂的高铁特质空间集群;高铁网络影响下的中国区域空间格局的渐变与重塑日趋复杂,“T”型轴带呈现出由空间极化向空间均衡转变,跨城流动性特征突显,加速空间对接与同城化进程。     

中国城市流动人口户籍迁移意愿的空间格局及影响因素——基于2012年全国流动人口动态监测调查数据

基于2012年全国流动人口动态监测调查数据和相关统计年鉴数据,对中国地级以上城市流动人口的户籍迁移意愿、空间格局及影响因素进行了系统分析。研究发现,中国城市流动人口户籍迁移意愿的整体水平并不高;等级高、规模大的城市流动人口的户籍迁移意愿高,而等级低、规模小的城市流动人口的户籍迁移意愿低;沿海城市群流动人口的户籍迁移意愿高,其他城市流动人口的户籍迁移意愿低,但内陆部分省会城市和交通区位与资源禀赋较好的中小城市也已经形成了一批流动人口的户籍迁移意愿高值区。中国城市流动人口户籍迁移意愿的空间分布特征受到流入城市和流动人口自身双重力量的影响,流入城市因素的正向影响作用大于流动人口自身因素。其中,流入城市的社会、经济发展水平和流动人口在流入城市的社会融合程度是核心要素,对城市流动人口户籍迁移意愿的提升具有正向的促进作用,而流动人口过于集中在次级劳动力市场的就业特征和较高的家庭财富与收入对户籍迁移意愿的提升却具有显著的抑制作用。最后,提出了相关政策启示。     

一种开源软件集成的空间矢量数据在线采集方法

空间数据是GIS应用的基础,经济高效地从网络获取空间数据具有重要意义。文章主要研究了网络地图环境下利用Web GIS技术和开源软件实现空间矢量数据在线采集和数据库存储的方法和技术。并且使用Google Map API、Ajax技术和Apache、My SQL开源软件开发一个基于Web平台的原型系统,实现了基于网络地图的矢量数据的在线获取、数据库存储、在线显示和数据库访问服务接口等功能,为获取空间数据提供了一种新方法。     

Vulnerability of Kuwait coast to sea level rise

Assessing coastal vulnerability to sea level rise (SLR) at local and regional scales is a fundamental step for designing successful long-term coastal management plans. This study was thus designed to assess Kuwait coastal vulnerability to SLR at four scenarios (.5, 1, 1.5 and 2 m). Potential inundated areas and the number of people at risk were estimated based on these SLR scenarios. A coastal vulnerability index (CVI) map of Kuwait was then computed based on the lowest scenario using eight parameters: elevation, coastal slope, geomorphology, distance to 20-m isobath, population, land use, cultural heritage and transportation. The geographic distribution of inundated areas at an SLR of .5 m revealed that the northern islands of Kuwait and coastal areas along Kuwait Bay would be highly impacted, whereas the coastal area near Shuaibah Port was the most influenced among the southern coasts. Most of the coastal area exhibited a moderate vulnerability to SLR, especially the northern islands. This study presented an initial vulnerability assessment for Kuwait coasts to SLR, which can be extended with more variables. The integrated remote sensing and geographic information system methodology demonstrated in this study can be applied in similar studies elsewhere.     

Engaging in the boycott,divestment, and sanctions (bds) debate

The goal of this forum is to garner attention to the issues surrounding the Boycott, Divestment, and Sanctions (BDS) campaign against Israel, to help a broad audience better understand the complexity of BDS, and to engage geographers in the BDS debate. Including the editorial introduction, seven different experts on the issues of Palestine/ Israel have written six essays on BDS for this forum. The six essays represent a wide range of opinions while also echoing some similar themes.     

Diagnosis of earth-fill dams by synthesised approach of sounding and surface wave method

The spatial distribution of the strength inside the earth-fill is identified by the sounding tests. In this research, the Swedish weight sounding (SWS) is employed, and the spatial high-density test is performed to identify the spatial correlation structure. Furthermore, the synthesised approach of the SWS and surface wave method, which is one of the geophysical method, is proposed to compensate the shortage of each approach. Consequently, the correlation structure of an earth-fill could be identified accurately, and the high resolution of the spatial distribution could be visualised based on the survey results.     

Exploring the spatial distribution patterns of South African Cape hakes using generalised additive models

We developed delta generalised additive models (GAMs) to predict the spatial distribution of different size classes of South African hakes, Merluccius capensis and M. paradoxus, using demersal trawl survey data and geographical (latitude and longitude) and environmental features (depth, temperature, bottom dissolved oxygen and sediment type). Our approach consists of fitting, for each hake size class, two independent models, a binomial GAM and a quasi-Poisson GAM, whose predictions are then combined using the delta method. Delta GAMs were validated using an iterative cross-validation procedure, and their predictions were then employed to produce distribution maps for the southern Benguela. Delta GAM predictions confirmed existing knowledge about the spatial distribution patterns of South African hakes, and brought new insights into the factors influencing the presence/absence and abundance of these species. Our GAM approach can be used to produce distribution maps for spatially explicit ecosystem models of the southern Benguela in a rigorous and objective way. Ecosystem models are critical features of the ecosystem approach to fisheries, and distribution maps constructed using our GAM approach will enable a reliable allocation of species biomasses in spatially explicit ecosystem models, which will increase trust in the spatial overlaps and, therefore, the trophic interactions predicted by these models.     

西太平洋暖池热盐结构盐度场变异的主模态

基于1950~2011年间的月平均温、盐度资料,以28℃等温线作为西太平洋暖池的定义标准,并取ΔT=-0.4℃,分别计算了暖池区(20°N~15°S,120°E~140°W)各格点混合层、障碍层和深层的平均盐度,构成了暖池热盐结构的盐度场.据此,运用EOF分解法分析了暖池热盐结构盐度距平场主要模态的变化特征及其与ENSO间的关系,并探讨了主要模态的年际变异机理.结果表明,暖池热盐结构盐度场第一模态揭示了盐度场变异的关键区位于暖池中部;该模态具有2~4a的年际变化和准10a的年代际变化,并在1977年前后经历了一次气候跃变(此外,深层盐度场第一模态还在1999年前后发生了一次气候跃变),且在跃变前后与不同类型的ENSO事件有较密切的联系.暖池中部混合层和障碍层盐度的变化比较一致,即在跃变前盐度为偏高期,而在跃变后则变为偏低期.暖池中部深层盐度在1977年以前和1999年之后皆处于偏高期,而在1978~1999年间则处于偏低期.而且,从混合层至深层,盐度的变化幅度逐渐变小.进一步分析表明,暖池中部混合层和障碍层盐度的年际变化主要是由纬向风、南赤道流(SEC)和降水共同引起的,即当东风增强(减弱)时,强(弱)SEC将携带更多(少)的高盐水进入混合层或潜沉至障碍层,同时局地降水的减少(增多),也使得混合层和障碍层的盐度增加(减少);深层盐度的年际变化主要是由SEC和赤道潜流(EUC)导致的,即当SEC增强(减弱)时,将有更多(少)的高盐水进入暖池,而当EUC增强(减弱)时则有更多(少)的低盐水流出暖池,从而使得暖池的深层盐度升高(降低).     

基于稳态碎岩方式的PDC钻头设计分析研究

自从20世纪80年代PDC复合片研发成功以来,PDC钻头由于其钻进性能强和耐磨性能好,在世界许多国家的石油钻井和地质勘探中得到了广泛应用,取得了很好的效果。但是,如何进一步提高其在钻探工程中的技术经济指标是一个很迫切的问题。俄罗斯博士Скоромных В. В.教授等对此进行多年研究,提出了稳态破碎岩石方式的思想,即在轴载和扭矩切力形成的合力R与切削面成垂直角度条件下,切入深度h不变时形成的一种碎岩方式。并在此基础上提出了一些设计PDC钻头方面的建议。     

1965-2015年新疆夏季不同等级降水的空间分布特征

根据新疆51个台站1965-2015年夏季逐日降水资料,将降水划分为小雨、中雨及大雨3个等级,分析了新疆近51 a夏季不同等级降水量、降水日数及降水强度的空间分布特征,并讨论了各等级降水日、降水量及降水强度与总降水量的空间相似程度以及各等级降水对夏季总降水的贡献。结果表明：新疆降水主要集中在夏季,并以小雨为主。以天山山脉为界,南北两疆降水空间分布存在明显差异,北疆夏季降水量（日）占年降水量（日）的36%~45%（36%~39%）,南疆夏季降水量（日）占年降水量（日）的51%~63%（48%~60%）;新疆夏季不同等级降水量、降水日及降水强度的空间分布不均匀。新疆夏季总降水量与各等级降水量的空间相似系数最为密切,与各等级降水强度的空间相似系数相对较小;新疆夏季小雨贡献率最大,中雨其次,大雨最小,夏季降水量和降水日的变化主要受小雨的影响。