A high-precision heuristic model to detect home and work locations from smart card data     

Nilufer Sari Aslam  Tao Cheng  James Cheshire 《地球空间信息科学学报》2019,22(1):1-11

Smart card-automated fare collection systems now routinely record large volumes of data comprising the origins and destinations of travelers. Processing and analyzing these data open new opportunities in urban modeling and travel behavior research. This study seeks to develop an accurate framework for the study of urban mobility from smart card data by developing a heuristic primary location model to identify the home and work locations. The model uses journey counts as an indicator of usage regularity, visit-frequency to identify activity locations for regular commuters, and stay-time for the classification of work and home locations and activities. London is taken as a case study, and the model results were validated against survey data from the London Travel Demand Survey and volunteer survey. Results demonstrate that the proposed model is able to detect meaningful home and work places with high precision. This study offers a new and cost-effective approach to travel behavior and demand research.  相似文献   

Re-examining urban region and inferring regional function based on spatial–temporal interaction     

Haiyan Tao  Keli Wang  Xuliang Li 《International Journal of Digital Earth》2019,12(3):293-310

Urban system is shaped by the interactions between different regions and regions planned by the government, then reshaped by human activities and residents’ needs. Understanding the changes of regional structure and dynamics of city function based on the residents’ movement demand are important to evaluate and adjust the planning and management of urban services and internal structures. This paper constructed a probabilistic factor model on the basis of probabilistic latent semantic analysis and tensor decomposition, for purpose of understanding the higher order interactive population mobility and its impact on urban structure changes. First, a four-dimensional tensor of time (T)?×?week (W)?×?origin (O)?×?destination (D) was constructed to identify the day-to-day activities in three time modes and weekly regularity of weekday/weekend pattern. Then we reclassified the urban regions based on the space clustering formed by the space factor matrix and core tensor. Finally, we further analysed the space–time interaction on different time scales to deduce the actual function and connection strength of each region. Our research shows that the application of individual-based spatial–temporal data in human mobility and space–time interaction study can help to analyse urban spatial structure and understand the actual regional function from a new perspective.  相似文献   

乘车软件应用前后出租车寻客路径偏好分析     

袁淑君  方志祥 《测绘地理信息》2019,44(3):94-98

本文尝试通过模拟出租车的路径选择探索乘车软件推广对出租车寻客路径偏好造成的影响。基于出租车的历史寻客轨迹,提取起终点对之间的出租车寻客路径集,选取路径的行程距离、历史乘客数目、历史载客行程距离等六个指标,对出租车的寻客路径选择行为进行多项Logit模型建模。通过分析模型的系数大小,得到各因子对出租车寻客路径选择的影响以及出租车在起终点对间寻客的偏好因子;通过统计出租车在各行政区内或跨行政区寻客时以各因子为偏好因子的起终点对数目,得到偏好因子的空间分布差异;此外,通过对比乘车软件推广前后的建模结果,得到出租车寻客路径选择偏好的变化规律。  相似文献   

转型期广州市居住迁移影响因素于户籍之间的比较   总被引：7，自引：3，他引：4  

刘望保  闫小培 《地理研究》2007,26(5):1055-1066

住房制度改革以来,中国城市居住迁移率大规模增加,成为城市重构和社会空间分异的基础动力。利用生命历程理论,通过家庭问卷调查,本文使用事件史模型动态地模拟了居住迁移,并比较外来人口与本地人口居住迁移影响因素的差异。整体来看,1980年以来年均居住迁移率呈上升趋势,外来人口的年均居住迁移率要比本地人口高。住房性质、婚姻变化、工作变动、居住区位和年份等变量都显著影响居住迁移,反映了住房制度改革、住房市场和分配环境、家庭生命周期等因素对居住迁移的影响;但影响程度户籍间的差异明显,工作地区位的变动导致通勤成本的变化是外来人口居住迁移的最显著影响因子,而家庭生命周期和住房特征变量是本地人口居住迁移的最显著影响变量,反映了两者之间的本质差别。居住区位对本地人口的居住迁移影响显著,内圈层居民的迁移率相对较低,而居住区位变量对外来人口的影响相对较弱。  相似文献   

劳动力区际流动及其人力资本再分配效应——基于技能互补性假说的理论与实证分析     

敖荣军 《地理与地理信息科学》2007,23(1):59-63

由于劳动力的异质性,不同技能劳动力之间的合作和互补可以获得递增收益。客观存在的技能互补性导致技能劳动力迁入与迁入地技能劳动力需求之间的正反馈关系,从而引发了劳动力区际流动与人力资本地区集中之间的累积循环。该文基于Giannetti提出的技能互补性假说,从一个新的角度对劳动力区际流动的动因进行理论与实证分析,并揭示该假说的区域经济学含义。  相似文献   

增强型AlGaN/GaN高电子迁移率晶体管高温退火研究     

王冲  全思  马晓华  郝跃  张进城  毛维 《海洋学报》2010,32(10):7333-7337

深入研究了两种增强型AlGaN/GaN高电子迁移率晶体管(HEMT)高温退火前后的直流特性变化.槽栅增强型AlGaN/GaN HEMT在500 ℃ N₂中退火5 min后,阈值电压由0.12 V正向移动到0.57 V,器件Schottky反向栅漏电流减小一个数量级.F注入增强型AlGaN/GaN HEMT在 400 ℃ N₂中退火2 min后,器件阈值电压由0.23 V负向移动到-0.69 V,栅泄漏电流明显增大.槽栅增强型器件退火过程中Schottky有效势垒  相似文献   

Open-system chemical behavior in deep Wilcox Group mudstones,Texas Gulf Coast,USA     

Ruarri J. Day-Stirrat  Kitty L. Milliken  Shirley P. Dutton  Robert G. Loucks  Stephen Hillier  Andrew C. Aplin  Anja M. Schleicher 《Marine and Petroleum Geology》2010

Wilcox Group mudstones have been mechanically and geochemically transformed over a temperature range of 20–200 °C. Our research controlled for provenance and age by sampling from five wells, parallel to the paleodepositional axis, all within the Houston delta system. Across the sampled depths, mudstone porosity has been reduced from ∼25 to <10% and bulk mineralogical change as documented by quantitative X-ray diffraction includes decreases in quartz, K-feldspar and kaolinite content whereas illite + illite − smectite, chlorite, and plagioclase increase. These mineral transformations transfer elements at a scale of less than 1 mm from one mineralogical form to another, however, X-ray fluorescence data suggest that among major elements only Al₂O₃ and TiO₂ are fully conserved within the system (trace-element ZrO₂ is also conserved). K₂O has been added to and SiO₂ released from the Wilcox Group mudstones. Cathodoluminescence and secondary electron imaging did not find this SiO₂ locally precipitated. We, therefore, document an open-system geochemical behavior.  相似文献   

Element mobility during continental collision: insights from polymineralic metamorphic vein within UHP eclogite in the Dabie orogen     

Y.‐M. SHENG  Y‐F. ZHENG  S‐N. LI  Z. HU 《Journal of Metamorphic Geology》2013,31(2):221-241

Metamorphic dehydration and partial melting are two important processes during continental collision. They have significant bearing on element transport at the slab interface under subduction‐zone P–T conditions. Petrological and geochemical insights into the two processes are provided by a comprehensive study of leucocratic veins in ultrahigh‐pressure (UHP) metamorphic rocks. This is exemplified by this study of a polymineralic vein within phengite‐bearing UHP eclogite in the Dabie orogen. The vein is primarily composed of quartz, kyanite, epidote and phengite, with minor accessory minerals such as garnet, rutile and zircon. Primary multiphase solid inclusions occur in garnet and epidote from the both vein and host eclogite. They are composed of quartz ± K‐feldspar ± plagioclase ± K‐bearing glass and exhibit irregular to negative crystal shapes that are surrounded by weak radial cracks. This suggests their precipitation from solute‐rich metamorphic fluid/melt that involved the reaction of phengite breakdown. Zircon U–Pb dating for the vein gave two groups of concordant ages at 217 ± 2 and 210 ± 2 Ma, indicating two episodes of zircon growth in the Late Triassic. The same minerals from the two rocks give consistent δ¹⁸O and δD values, suggesting that the vein‐forming fluid was directly derived from the host UHP eclogite. The vein is much richer in phengite and epidote than the host eclogite, suggesting that the fluid is associated with remarkable concentration of such water‐soluble elements as LILE and LREE migration. Garnet and rutile in the vein exhibit much higher contents of HREE (2.2–5.7 times) and Nb–Ta (1.8–2.0 times) than those in the eclogite, indicating that these normally water‐insoluble elements became mobile and then were sunken in the vein minerals. Thus, the vein‐forming agent would be primarily composed of the UHP aqueous fluid with minor amounts of the hydrous melt, which may even become a supercritical fluid to have a capacity to transport not only LILE and LREE but also HREE and HFSE at subduction‐zone metamorphic conditions. Taken together, significant amounts of trace elements were transported by the vein‐forming fluid due to the phengite breakdown inside the UHP eclogite during exhumation of the deeply subducted continental crust.  相似文献   

Time, idealisation and international development: promoting Canadian co-management in northern Russia     

Elana Wilson 《Area》2007,39(3):323-330

In this article, I trace the efforts of a development team working to promote a Canadian approach to natural resources management in the Russian North. These development workers used two communication strategies related to time and history to render Canadian knowledge mobile and applicable to a new location: (1) imagining today's Russian North as equivalent to the Canadian northern past and (2) reframing and idealising the Canadian past and present to make the governance export less discursively 'messy' for an outside audience. The relative failure of these communicative strategies points to the need for richer dialogue in efforts to move knowledge cross-culturally.  相似文献   

GIS‐assisted modelling for debris flow hazard assessment based on the events of May 1998 in the area of Sarno,Southern Italy: Part I. Maximum run‐out     

G. Toyos  D. Oramas Dorta  C. Oppenheimer  M. T. Pareschi  R. Sulpizio  G. Zanchetta 《地球表面变化过程与地形》2007,32(10):1491-1502

Based on the debris flow events that occurred in May 1998 in the area of Sarno, Southern Italy, this paper presents an approach to simulate debris flow maximum run‐out. On the basis of the flow source areas and an average thickness of 1·2 m of the scarps, we estimated debris flow volumes of the order of 10⁴ and 10⁵ m³. Flow mobility ratios (ΔH/L) derived from the x, y, z coordinates of the lower‐most limit of the source areas (i.e. apex of the alluvial fan) and the distal limit of the flows ranged between 0·27 and 0·09. We performed regression analyses that showed a good correlation between the estimated flow volumes and mobility ratios. This paper presents a methodology for predicting maximum run‐out of future debris flow events, based on the developed empirical relationship. We implemented the equation that resulted from the calibration as a set of GIS macros written in Visual Basic for Applications (VBA) and running within ArcGIS. We carried out sensitivity analyses and observed that hazard mapping with this methodology should attempt to delineate hazard zones with a minimum horizontal resolution of 0·4 km. The developed procedure enables the rapid delineation of debris flow maximum extent within reasonable levels of uncertainty, it incorporates sensitivities and it facilitates hazard assessments via graphic user interfaces and with modest computing resources. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献