【摘 要】
：
Urbanization is one of the most impactful human activities across the world today affecting the quality of urban life and its sustainable development. Urbanization in Africa is occurring at an unprecedented rate and it threatens the attainment of Sustaina
【机 构】
：
State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing,Wuhan Univer
论文部分内容阅读
Urbanization is one of the most impactful human activities across the world today affecting the quality of urban life and its sustainable development. Urbanization in Africa is occurring at an unprecedented rate and it threatens the attainment of Sustainable Development Goals (SDGs). Urban sprawl has resulted in unsustainable urban development patterns from social, environmental, and economic perspectives. This study is among the first examples of research in Africa to combine remote sensing data with social media data to determine urban sprawl from 2011 to 2017 in Morogoro urban municipality, Tanzania. Random Forest (RF) method was applied to accomplish imagery classification and location-based social media (Twitter usage) data were obtained through a Twitter Application Programming Interface (API). Morogoro urban municipality was classified into built-up, vegetation, agriculture, and water land cover classes while the classification results were validated by the generation of 480 random points. Using the Kernel function, the study measured the location of Twitter users within a 1 km buffer from the center of the city. The results indicate that, expansion of the city (built-up land use), which is primarily driven by population expansion, has negative impacts on ecosystem services because pristine grasslands and forests which provide essential ecosystem services such as carbon sequestration and support for biodiversity have been replaced by built-up land cover. In addition, social media usage data suggest that there is the concentration of Twitter usage within the city center while Twitter usage declines away from the city center with significant spatial and numerical increase in Twitter usage in the study area. The outcome of the study suggests that the combination of remote sensing, social sensing, and population data were useful as a proxy/inference for interpreting urban sprawl and status of access to urban services and infrastructure in Morogoro, and Africa city where data for urban planning is often unavailable, inaccurate, or stale.
其他文献
高喜马拉雅淡色花岗岩是印度与亚洲板块碰撞过程中,地壳深熔作用的产物.尽管自由水对高喜马拉雅淡色花岗岩形成的重要性已被多次报导,但仍存在许多争议.本研究汇编了高喜马拉雅淡色花岗岩的全岩地球化学数据,证明高喜马拉雅淡色花岗岩可以由脱水熔融形成和水致熔融形成.进一步通过热力学模拟获得锆石结晶,并与锆石Ti温度计比较,限定了不同熔融反应中熔体的水含量.模拟结果显示锆石的结晶温度主要受控于初始熔体的水含量,可以依据初始熔体水含量的高低将高喜马拉雅淡色花岗岩分为两组:有自由水参与的初始熔体具有高含水量,约为5％;贫水
借助稀释通道采样系统,采集了5种民用煤(3种块煤、1种蜂窝煤和1种煤球)燃烧排放的PM2.5和单颗粒样品.利用ICP-MS分析了PM2.5中16种金属元素(Mg、Al和K 3种轻金属;V、Cr、Mn、Fe、Co、Ni、Cu、As、Rb、Sr、Cd、Ba和Bi共13种重金属)的含量,并运用TEM和SEM-EDX研究了燃煤排放粒子的单颗粒特征.结果显示,蜂窝煤和煤球燃烧排放的颗粒物中金属元素质量分数分别为29.7％和33.0％,高于块煤燃烧排放颗粒物中金属元素的质量分数8.9％～23.7％;Al是民用煤燃烧排
中国是世界上盐类资源极为丰富且盐湖数量最多的国家之一,其中海相蒸发岩地层分布广泛,包括震旦系、寒武系、奥陶系、石炭系、三叠系、侏罗系、白垩系、古近系、第四系. 成盐环境主要为泛大洋和特提斯两类.
吉林省蛟河市东北部红山组浅变质碎屑岩沉积时限上限在250 Ma左右,其中粉砂质板岩碎屑锆石年龄范围在867 ～ 184Ma,泥质粉砂岩碎屑锆石年龄范围在810 ～181Ma,两者碎屑锆石年龄大致可分为7个年龄段.结合近年来区域研究成果,充分说明蛟河市东北部红山组浅变质碎屑岩物质来源于佳木斯地块等不同时期不同构造活动单元中,具有多物源特征,对研究吉中乃至东北地区地壳演化具有重要意义.
选取内蒙古额尔古纳红水泉地区奥陶系乌宾敖包组石英砂岩进行碎屑锆石U-Pb年龄、原位Lu-Hf同位素研究,尝试限定该地层形成时代及碎屑物质来源,并探讨其沉积大地构造环境.结果显示,采自该地层的2个砂岩样品中的碎屑锆石多数发育典型的岩浆振荡生长环带,呈自形–半自形且具有较高的Th/U值(0.12～1.63),均暗示它们多数为岩浆成因.结合微量元素特征及稀土元素配分模式图,认为碎屑锆石寄主岩石应为花岗质杂岩体.2个砂岩样品具有相似的年龄和Hf同位素组成,锆石年龄分布大致可分为3个主要年龄区间:(1)440～54
以吉扶地6井为主,结合邻井资料研究了松辽盆地东南隆起三井子地区青山口组油页岩特征.吉扶地6井于1058.6～1079.9 m处青山口组中见有油页岩5层,累计厚度10.3 m,含油率(3.5～10.5)％,平均5.46％,为中等品质油页岩.具有有机质丰度高的特征,平均TOC 7.72％,有机质类型主要为Ⅰ型,有机质成熟度为未熟→低熟.同时该井青山口组油页岩垂向上分布较集中,品质变化呈低→高→低→高的特征,厚度变化为薄→厚→薄→厚的特征.研究区油页岩分布特征显示,青山口组油页岩累计厚度西北大,东南小,总体含油
COVID-19 outbreaks in China in late December 2019, then in the United States (US) in early 2020. In the initial wave of diffusion, the virus respectively took 14 and 33 days to spread across the provinces/states in the Chinese mainland and the coterminous
To contain the outbreak of COVID-19 in Wuhan, unprecedented interventions, including city lockdown and community closure, have been implemented. However, most of the current studies focused on evaluation of the city lockdown, but paid limited attention to
本文对和安河金矿地质特征及找矿标志进行了总结.矿体呈脉状、细脉状赋存于燕山期花岗闪长岩中,主要受北北西向断裂构造控制,矿石类型以含金蚀变岩型为主,其次为含金石英脉型.矿石结构以半自形晶—他形晶粒状结构为主;构造主要为浸染状构造.矿床属于中高温热液蚀变矿床,硅化、绿泥石化、黄铁矿化是蚀变矿物找矿标志,土壤测量Au元素异常是地球化学找矿标志.
对中印度洋海盆14个站位的表层沉积物进行了稀土元素(REE+Y,简称REY)分布特征和富集规律研究.结果表明,样品中REY主要富集于沸石黏土和远洋黏土中(稀土元素总量最高为1239×10?6),且明显富集钇(Y)等重稀土元素(Y富集系数高达14.1,重稀土元素和Y富集系数最高为11.6);富稀土沉积物呈明显Ce亏损,发育在受南极底层流影响的氧化环境中;鱼牙骨等生物磷灰石是深海稀土富集的重要富集矿物或宿主矿物.样品地球化学特征表明,深海富稀土沉积是有别于已知陆地稀土矿床的一种新类型.研究区沉积物中REY的富