Simulating urban land-use changes at a large scale by integrating dynamic land parcel subdivision and vector-based cellular automata   总被引：1，自引：0，他引：1  

Yao Yao  Penghua Liu  Ye Hong  Yatao Zhang 《International journal of geographical information science》2017,31(12):2452-2479

Cellular automata (CA) have been widely used to simulate complex urban development processes. Previous studies indicated that vector-based cellular automata (VCA) could be applied to simulate urban land-use changes at a realistic land parcel level. Because of the complexity of VCA, these studies were conducted at small scales or did not adequately consider the highly fragmented processes of urban development. This study aims to build an effective framework called dynamic land parcel subdivision (DLPS)-VCA to accurately simulate urban land-use change processes at the land parcel level. We introduce this model in urban land-use change simulations to reasonably divide land parcels and introduce a random forest algorithm (RFA) model to explore the transition rules of urban land-use changes. Finally, we simulate the land-use changes in Shenzhen between 2009 and 2014 via the proposed DLPS-VCA model. Compared to the advanced Patch-CA and RFA-VCA models, the DLPS-VCA model achieves the highest simulation accuracy (Figure-of-Merit = 0.232), which is 32.57% and 18.97% higher respectively, and is most similar to the actual land-use scenario (similarity = 94.73%) at the pattern level. These results indicate that the DLPS-VCA model can both accurately split the land during urban land-use changes and significantly simulate urban expansion and urban land-use changes at a fine scale. Furthermore, the land-use change rules that are based on DPLS-VCA mining and the simulation results of several future urban development scenarios can act as guides for future urban planning policy formulation.  相似文献   

Extracting and analyzing semantic relatedness between cities using news articles   总被引：1，自引：0，他引：1  

Yingjie Hu  Xinyue Ye  Shih-Lung Shaw 《International journal of geographical information science》2017,31(12):2427-2451

News articles capture a variety of topics about our society. They reflect not only the socioeconomic activities that happened in our physical world, but also some of the cultures, human interests, and public concerns that exist only in the perceptions of people. Cities are frequently mentioned in news articles, and two or more cities may co-occur in the same article. Such co-occurrence often suggests certain relatedness between the mentioned cities, and the relatedness may be under different topics depending on the contents of the news articles. We consider the relatedness under different topics as semantic relatedness. By reading news articles, one can grasp the general semantic relatedness between cities; yet, given hundreds of thousands of news articles, it is very difficult, if not impossible, for anyone to manually read them. This paper proposes a computational framework which can ‘read’ a large number of news articles and extract the semantic relatedness between cities. This framework is based on a natural language processing model and employs a machine learning process to identify the main topics of news articles. We describe the overall structure of this framework and its individual modules, and then apply it to an experimental dataset with more than 500,000 news articles covering the top 100 US cities spanning a 10-year period. We perform exploratory visualizations of the extracted semantic relatedness under different topics and over multiple years. We also analyze the impact of geographic distance on semantic relatedness and find varied distance decay effects. The proposed framework can be used to support large-scale content analysis in city network research.  相似文献   

中国春运人口省际流动的时空与结构特征   总被引：3，自引：1，他引：2  

赵梓渝  魏冶  庞瑞秋  杨冉  王士君 《地理科学进展》2017,36(8):952-964

本文通过构建人口省际流动的关系矩阵,透视2015年中国春节期间人口省际流动的动态过程、网络特征,并对各省人口流入、流出的规模差异进行测度。研究结论如下：①春节前后中国各省每日人口净流入人次存在显著的规律性特征,2月13-17日和2月25日-3月1日为各省节前返乡流和节后返工流期间人口净流入、流出峰值时段,可作为基于春运研究中国人口省际流动的重要依据;②识别了14个人口净流入省、17个人口净流出省,净流入位序前六省和后八省分别吸纳和提供了全国9成人口的集聚与扩散。人口主要流入省的沿海绵延和主要流出省的中部“人口塌陷”共同构成了双纵格局;③各省流出首位流的指向特征显著,南方人口流出省的流出指向存在共性,京津、长三角、珠三角地区的人口集聚路径存在差异。④移动数据为发掘人口流动过程中蕴含的丰富信息提供了平台,基于节后、节前净流入值差值的方法可以有效识别中国人口流动的规模差异、属性特征。通过与以往研究对比,证实了移动数据与基于人口普查数据研究的诸多结论相似性。  相似文献   

长江三角洲地区门户功能演化与驱动机理     

蒋自然  曹有挥  叶士琳 《地理科学》2017,37(7):987-996

采用综合指数评价、基尼系数、标准差椭圆等方法分析了2004~2014年长江三角洲地区门户功能的空间格局及其演化过程。结果表明：① 长江三角洲地区城市门户功能上升趋势明显,空间上由“一极三强”的格局演变为“一极四强”;② 各类门户功能的空间差异整体上呈缩小趋势,其中国际门户功能的差异明显大于综合和国内门户功能,而组间差异是导致门户功能差异的主要原因;③ 所有门户功能均由南-北方向分布向东-西方向分布转型。长三角地区门户功能的演化是由多重因素驱动形成的,国内和国际门户功能的驱动机理存在明显差异。  相似文献   

东营石油装备制造业创新网络演化研究   总被引：6，自引：2，他引：4  

叶琴  曾刚  杨舒婷  陈弘挺 《地理科学》2017,37(7):1023-1031

采用社会网络分析方法,借助Ucinet、ArcGIS等软件工具,从多维邻近的视角出发,对东营石油装备业创新网络演化进行分析研究,研究发现：首先,多维邻近对东营创新网络发展产生了重要影响,且不同网络发展阶段（培育、起步、成长）主导的邻近因子不同。这一方面证实了Boschma多维邻近性的相关理论假说,另一方面指出多维邻近因子与东营创新网络演变的不同关联。其次,高校、大型国有企业是东营创新网络的知识源泉和组织者。中国石油大学（华东)、胜利油田集团企业发挥了主导作用,这与国外中小型创新企业发挥主导作用的情形有很大差异。  相似文献   

用深井观测的地震研究东川地区随深度变化的场地放大因子.          下载免费PDF全文

罗娣华  蒋乐群  赤松纯平  陈敏恭  叶建庆  蔡绍平  刘学军 《地震学报》2001,23(1):68-78

采用中日合作，分别布设于东川垂直竖井中地下200ｍ、100ｍ 和地面３个位置的高精度数字化地震仪记录的地方震资料（震中距8.5～95ｋｍ，震级ML1.3～5.1），用频谱比的分析方法计算了东川地区不同深度（－100ｍ 和地面）的场地放大因子．在８个频率（f ＝0.75，1.0，1.5，2，3，4，5和12Ｈｚ）上所对应的在-100ｍ 处的3个分向（N-S，E-W，U-D）的场地放大因子（与-200ｍ 处相比），当0.75Ｈｚ f 2Ｈｚ时，为1.0～1.49；当2Ｈｚ＜ f ＜12Ｈｚ时，为0.47～0.99；在地面，3个分向在8个频率上所对应的场地放大因子（与-200ｍ 处相比）均大于1，其值为1.6～7.63．-100ｍ 处的Ｓ波和尾波场地放大因子与地面的Ｓ波和尾波的场地放大因子的相关系数，当0.75Ｈｚ f 2Ｈｚ频段时，分别为0.82和0.81；当2Ｈｚ＜ f＜12Ｈｚ频段时，分别为0.47和0.45．   相似文献   

气温变幅较大华南出现寒露风连阴雨时间长秋收秋播受影响     

叶殿秀 《气象》2001,27(1)

10月份，全国大部地区降水偏多，汉江流域、淮河流域、江南、西南东部等地出现了12～18天严重连阴雨天气，琼、粤、陕等省出现了暴雨或特大暴雨，局部洪涝灾害严重。月平均气温，除华南东部沿海偏高2～3℃，北疆偏低2～4℃外，全国其余大部接近常年；月内气温起伏较大。全国大部地区日照条件较差，东部农业区月日照时数偏少50～100小时。总体而言，本月全国大部地区降水丰沛，对缓解旱情及塘库湖泊蓄水有利，但持续阴雨寡照，对秋作物的成熟和收晒及冬小麦、油菜的播种出苗不利。  相似文献   

江南持续阴雨 秋收秋播受阻 东部地区大雾 交通受到影响     

Ye Dianxiu 《气象》2001,27(2)

11月份，全国大部地区气温偏低，部分地区偏低幅度较大。月内降 水过程较频繁且分布不均，北疆、青海大部、长江下游等地区降水明显偏多，北疆出现雪灾 ，尤其长江下游地区持续出现连阴雨天气，给当地秋收秋播及秋播作物幼苗生长造成一定影 响。华北、黄淮等地出现大雾天气，给人们出行、交通运输等带来不便。 1　大部气温偏低，气温变幅大 　　月内气温变幅较大。上旬和中旬，全国大部地区气温偏低，尤其中旬气温偏低幅度大，达3 ～5℃；下旬，除北疆、东北大部气温偏低较明显外，全国其余大部及南疆南部、云南大部 正常或稍偏高外，全国其余大部地区气温偏低，其中东北地区、华北北部、江南西部及北疆 、河南西部和南部、广西东北部等地偏低2～4℃。月内，黄淮南部、江淮、江南北部及陕南 、贵州等地相继出现了初霜冻，大部地区初霜冻日期比常年偏早3～11天。由于热量条件较 差，北方冬小麦生长分蘖、形成壮苗及南方秋播作物幼苗生长受到不良影响，但低温能在一 定程度上抑制病虫越冬。  相似文献   

20世纪全球增暖最显著的区域   总被引：6，自引：0，他引：6  

Zeng Zhaomei  Yan Zhongwei  Ye Duzheng 《大气科学进展》2001,18(4):481-496

Having analyzed a global grid temperature anomaly data set and some sea level pressure data during the last century, we found the following facts. Firstly, the annual temperature change with a warming trend of about 0.6℃/100 years in the tropical area over Indian to the western Pacific Oceans was most closely correlated to the global mean change. Therefore, the temperature change in this area might serve as an indicator of global mean change at annual and longer time scales. Secondly, a cooling of about -0.3℃ / 100 years occurred over the northern Atlantic. Thirdly, a two-wave pattern of temperature change, warming over northern Asia and northwestern America and cooling over the northern Atlantic and the northern Pacific, occurred during the last half century linked to strengthening westerlies over the northern Atlantic and the weakening Siberian High. Fourthly, a remarkable seasonal difference occurred over the Eurasian continent, with cooling (warming) in winter (summer) during 1896-1945, and warming (cooling) in winter (summer) during 1946-1995. The corresponding variations of the North Atlantic Oscillation and the Southern Oscillation were also discussed.  相似文献   

Evaluation of Petroleum System in Xihu Depression, East China Sea Shelf Basin     

Lü Delin 《中国地质大学学报(英文版)》2001,12(4)

Since Dow (l972) proposed the concept of oil system atthe AAPG annual meeting in l972, after unremitting effol.tsand progressive perfection, it has become the petroleum systemaccepted by numerous geologists at present. The concept of pe-troleum system was introduced to our country in early l990s(I)ou, l999). In fact, as early as the 1960s, based on the hy-drocarbon exploration and development practice at Songliao ba-sin and Bohai Bay basin, some viewpoints similar to petroleumsystem have be…  相似文献