Exploring the link between urban form and work related transportation using combined satellite image and census information: Case of the Great lakes region     

《International Journal of Applied Earth Observation and Geoinformation》2016

Aspects of urban transportation have significant implications for resource consumption and environmental quality. The level of travel activity, the viability of various modes of transportation and hence the level of transportation-related emissions are influenced by the structure of cities, i.e., their urban forms. While it is widely recognized that satellite remote sensing can provide spatial information on urban land cover and land use, its effective use for understanding impacts of urban form on issues such as transportation requires that this information be integrated with relevant demographic information. A comprehensive bi-national urban database, the Great Lakes Urban Survey (GLUS), comprising all cities with populations in excess of 200,000 has been created from Landsat imagery and national census and transportation survey information from Canada and the United States. A suite of analysis tools are proposed to utilize information sets such as GLUS to investigate the link between urban form and work-related travel. A new indicator, the Employment Deficit Measure (EDM), is proposed to quantify the balance between employment and worker availability at different transit horizons and hence to assess the viability of alternate modes of transportation. It is argued that the high degree of residential and commercial/industrial land uses greatly impact travel to work mode options as well as commute distance. A spatial interaction model is developed and found to accurately predict travel distance aggregated at the census tract level. We argue that this model could also be used to explore the relative levels of travel activity associated with different urban forms.  相似文献   

An averaging method to study the motion of lunar artificial satellites II: Averaging and Applications     

Daniel Steichen 《Celestial Mechanics and Dynamical Astronomy》1998,68(3):225-247

On this, the second part of a two part study (Steichen, 1998) we further develop a semi-analytical theory for a lunar artificial satellite. This theory is obtained by averaging analytically the Hamiltonian function over period up to a month. The averaged equations are then numerically integrated. The solution is free from singularities at e = 0 and I = 0 and is not expanded in powers of these variables. In the last section, the analytic work is applied to characteristic examples to validate the method used. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

A kind of informationon short-term and imminent earthquake precursors-research on atmospheric electric field anomalies before earthquakes     

郝建国  唐天明  李德瑞 《地震学报(英文版)》1998,(1)

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A kind of information on short-term and imminent earthquake precursors—research on atmospheric electric field anomalies before earthquakes     

Jian-Guo Hao  Tian-Ming Tang  De-Rui Li 《地震学报(英文版)》1998,11(1):121-131

The long-time practice of observational research on earthquake prediction has shown that the information on short-term and imminent earthquake precursors can hardly be detected, but it is very important for practical and effective earthquake prediction. The result of analysis and study in this paper has shown that the anomaly of quasi-static atmospheric electric field may be a kind of reliable information on short-term and imminent earthquake precursors. On such a basis, the 20 years’ continuous and reliable data of atmospheric electric field observed at the Baijiatuan seismic station are used to study the correlation between the anomalies in seismic activity and relative quiet periods bear on the occurrence of near earthquakes within 200 km range around Beijing after the Tangshan earthquake. The observational results recently reported before hand in written form and earthquakes that actually occurred in near field in corresponding time periods are compared and analyzed. The efficacy of these written prediction opinions about near earthquakes in the recent 10 years is tested. From the test results, the brilliant prospect that the anomaly of quasi-static atmospheric electric field may really become a reliable mark for making short-term and imminent earthquake predictions is discussed. Besides, as a preliminary step, some judgment indexes for predicting earthquakes by use of the observational data of atmospheric electric field before earthquakes are put forward. In the last part, it is pointed out that it would be possible to obtain more believable judgment indexes for determining the three elements of near earthquakes before greater earthquakes (M _S≥5) only if a relatively reasonable station network (2–4 stations every 10 000 km²) is deployed and further investigation is made. Contribution No. 97A0040, Institute of Geophysics, State Seismological Bureau, China. This subject is sponsored by Program No. 95-04-05-01-04, State Seismological Bureau, China.  相似文献   

安徽茅坦A型花岗岩研究   总被引：22，自引：1，他引：21  

吴才来  黄许陈 《地质学报》1998,72(3):237-248

安徽茅坦花岗岩体是由４次侵入的细粒花岗岩、花岗斑岩、中粒花岗岩和粗粒花岗岩组成的复式岩体。各期次岩石具有高硅,富碱,富ＬＲＥＥ、Ｙ,Ｎｂ,Ｚｒ等大离子高电价元素及低Ａｌ、Ｍｇ,Ｃａ、Ｎｉ、Ｃｒ,Ｔｉ,Ｖ的特点,与国内外Ａ型花岗岩相似。岩石中副矿物种类聚多,以含碳硅石,磷钛矿等深源矿物为特征。锆石晶形以正锥面（１１１）和四方柱面（１１０）最为发育,与一般Ｉ型花岗岩有明显的差异。研究表明,该复式岩体为  相似文献   

路网形态对城市购物中心布局的影响 ——以福建厦门岛为例     

阚小溪  高悦尔  杨春  崔桂籽 《地域研究与开发》2021,40(2):68-73

以福建厦门岛为例,通过空间句法结合核密度估计法等GIS技术,在分析不同规模(社区、市区)购物中心和路网形态分布的基础上,通过逐步回归方法探究路网形态对城市购物中心布局的影响。结果表明:购物中心总体呈现多中心轴向发展的集聚与扩散并存的空间分布特征,购物中心的级别越高,聚集程度越弱;路网形态的空间差异显著,高穿行度与整合度的路网形成从厦门岛中西部地区向四周延伸辐射的路网形态,这与岛内的主要交通走廊契合;局部路网形态对购物中心的影响大于全局性路网,购物中心对路网形态的穿过与可达特性均有较大的依赖性;社区购物中心与局部路网的穿行度和整合度正相关,市区购物中心与全局路网的穿行度正相关。  相似文献   

成都市主城区空间形态与街区活力的关联性分析     

鲁仕维  黄亚平  赵中飞 《地域研究与开发》2021,40(1):73-77

运用开放数据平台提供的城市基础信息数据和居民日常出行活动的位置签到数据,借助GIS技术建立城市街区空间形态测度体系,引入空间回归模型,揭示成都市主城区658个街区的空间形态与街区活力之间的关联关系,辅助城市街区空间设计和优化,指导精细化的城市规划实践。结果表明:街区空间形态与空间活力之间具有较强的关联性。城市空间形态指标和社会经济属性因素可以较大程度地解释街区活力的空间变异特征。其中,功能多样性对街区活力的营造起到的积极促进作用最强,而建筑密度的促进作用明显强于容积率。  相似文献   

安徽二叠纪龙潭组煤中潜在毒害元素分布的因子分析研究   总被引：1，自引：0，他引：1  

钱让清  杨晓勇 《煤田地质与勘探》2003,31(1):11-14

运用因子分析法对安徽二叠纪龙潭组煤层中S、Fe、As、CA、Se、Hg、Ti和Zn等的分布规律进行了研究,研究了这些潜在毒害元素的相关关系,并结合元素地球化学知识给出了这些元素在煤中赋存状态的信息。结果表明:煤层中Pb以方铅矿形式存在于煤中;As、Hg、Sb主要赋存于次生黄铁矿中;Zn和Se主要赋存于闪锌矿中;从元素地球化学性质上讲,Cd应赋存于闪锌矿中,但由于其在煤中的含量较低,造成分析数据的误差较大,从而掩盖了它与Zn之间的相关关系;Ti的赋存状态较为复杂。  相似文献   

黄河下游花园口河段洪水涨落过程中河床横断面形态的调整          下载免费PDF全文

张欧阳  许炯心  张红武 《水科学进展》2003,14(4):401-406

利用黄河下游1950-1985年间218场洪水资料,讨论了黄河下游花园口河段洪水起涨和回落过程中河床形态调整的不同过程.在洪水起涨阶段,花园口河段河床宽深比以增大为主,且洪水最大含沙量越大,宽深比增大的幅度越大,洪峰增幅比在3以下时,宽深比随最大含沙量的增大而增大,洪峰增幅比在3以上时,呈随含沙量的增大而减小的趋势.在洪水回落阶段,宽深比的变化方向则相反.在含沙量较小时,河床宽深比的减小主要发生在洪水起涨阶段,在含沙量很大时,河床宽深比的减小主要发生在洪水回落阶段.  相似文献   

海洋底层水成矿金属组分存在形式和沉淀矿物的定量研究   总被引：2，自引：0，他引：2  

张宏达  汪珊  杨振京  李政红 《地理与地理信息科学》2003,19(2):56-59

该文以测试资料为依据，以溶液化学平衡反应模型理论计算为手段，对海盆和底层水的成矿金属组分存在形式和沉淀矿物进行定量计算，发现海洋底层水系统为非平衡的地球化学动力系统，系统中发生着活跃的物质和能量交换与转移，海洋底部现代正在发生沉淀作用。海洋底层水是一种典型的稀金属成矿溶液，除Fe在洋盆存在高价态外，Fe的其它组分形式及Mn、Cu、Ni、Co4种金属组分均以低价态的组分形式存在，它们不可能通过化学沉淀作用生成以高价态锰矿物为主的结核。Mn、Fe主要以胶体和微粒形态存在，其浓度比溶解态的浓度要高出数百倍甚至千倍。这些胶状的金属微粒流直接参与结核的生成，胶体化学作用是结核生成的主要成矿作用。  相似文献