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201.
202.
针对高分辨率遥感影像地物空间结构复杂、光谱纹理信息丰富的特点,该文提出一种基于Levene检验及模糊评价的遥感影像变化检测方法。首先,对预处理后的两期影像叠置分割得到图斑对象,提取其光谱、纹理等特征;其次,利用改进的Levene检验法统计各图斑变化信息得到候选变化图斑,经IHS变换获取影像色调信息,结合纹理特征进行变化向量分析;最后,通过迭代的方式确定阈值并计算候选图斑的变化隶属度,确定最终变化区域。选取江苏省某地区ZY-3高分辨率遥感影像进行实验,结果表明:改进的Levene检验法很大程度地减少了后续的计算量,提高了变化检测精度,对于相对辐射差异较大的非变化图斑具有良好的容错性;采用色调-纹理特征及模糊评价法可以有效地降低漏检及虚检率,提高变化检测精度。 相似文献
203.
针对传统的建筑物建模方法需要大量人机交互操作,建模过程复杂和成本高的问题,该文提出一种参数化建筑物三维建模方法。首先,以高分辨率遥感影像和建筑物立面影像作为数据源,在遥感和GIS软件平台的支持下,提取建筑物的底面边界、高度、楼层数、层高和屋顶类型等空间数据和属性数据,并将其保存至GIS空间数据库。其次,提出基于拉伸、拆分、添加结构面过程的建筑物主体结构建模方案,并设计了模型自动生成算法。进一步,采用Ruby面向对象语言,通过调用SketchUp平台的应用程序接口函数,结合编程实现了建筑物的自动化建模。最后,开发了建筑物参数化建模插件。实际建模实验成果表明:该方法能够显著降低建模人员劳动强度,提高建模效率。 相似文献
204.
The Kualiangzi landslide was triggered by heavy rainfalls in the “red beds” area of Sichuan Basin in southwestern China. Differing from other bedrock landslides, the movement of the Kualiangzi landslide was controlled by the subvertical cracks and a subhorizontal bedding plane (dip angle < 10°). The ingress of rainwater in the cracks formed a unique groundwater environment in the slope. Field measurement for rainfall, groundwater movement, and slope displacement has been made for the Kualiangzi landslide since 2013. The field monitoring system consists of two rainfall gauges, seven piezometers, five water-level gauges, and two GPS data loggers. The equipments are embedded near a longitudinal section of the landslide, where severe deformation has been observed in the past 3 years. The groundwater responses to four heavy rainfall events were analyzed between June 16 and July 24 in 2013 coincided with the flood season in Sichuan. Results showed that both of the water level and the pore-water pressure increased after each rainfall event with delay in the response time with respect to the precipitation. The maximum time lag reached 35 h occurred in a heavy rainfall event with cumulative precipitation of 127 mm; such lag effect was significantly weakened in the subsequent heavy rainfall events. In each presented rainfall event, longer infiltration period in the bedrock in the upper slope increased the response time of groundwater, compared to that of in the gravels in the lower slope. A translational landslide conceptual model was built for the Kualiangzi landslide, and the time lag was attributed to the gradual formation of the uplift pressure on the slip surface and the softening of soils at the slip surface. Another important observation is the effect on the slope movement which was caused by the water level (H w) in the transverse tension trough developed at the rear edge of the landslide. Significant negative correlation was found for H w and the slope stability factor (F s), in particular for the last two heavy rainfall events, of which the drastic increase of water level caused significant deterioration in the slope stability. The rapid drop (Δ?=?22.5 kPa) of pore-water pressure in the deep bedrock within 1 h and the large increase (Δ?=?87.3 mm) of surficial displacement were both monitored in the same period. In the end, a four-level early warning system is established through utilizing H w and the displacement rate D r as the warning indicators. When the large deformation occurred in flood season, the habitants at the leading edge of the landslide can be evacuated in time. 相似文献
205.
利用区域气候模式RegCM4.5,分别选取不同陆面参数化方案和空间分辨率,对5个长江流域降水异常年份进行短期气候回报试验,分析对气温和降水预测效果的影响及其最优组合。结果表明:空间分辨率的提高可以改善流域降水和气温的预测性能;而不同陆面方案引起的地表净辐射能量分布不同及其地表蒸散差异,最终导致流域内气温和降水预测效果不一致。RegCM(CLM4.5+30 km)对流域内小雨预测结果最好,而RegCM(BATS+30 km)预测流域内大雨和暴雨效果最优;RegCM(CLM3.5+30 km)对流域内气温预测能力最好。 相似文献
206.
以日本宇宙航空研究开发机构(JAXA)提供的精密星历为参考,对QZSS MICHIBIKI卫星发布的实时轨道和钟差数据进行了评估。数值结果表明,QZSS MICHIBIKI卫星的实时轨道精度优于11 cm,实时钟差优于0.56 ns;GPS卫星的实时轨道精度优于5 cm,实时钟差优于0.4 ns。通过比较得知,QZSS MICHIBIKI卫星的实时轨道和钟差精度明显低于GPS卫星。 相似文献
207.
The oceanic and atmospheric conditions and the related climate impacts of the 2015/16 ENSO cycle were analyzed, based on the latest global climate observational data, especially that of China. The results show that this strong El Niño event fully established in spring 2015 and has been rapidly developing into one of the three strongest El Niño episodes in recorded history. Meanwhile, it is also expected to be the longest event recorded, attributable to the stable maintenance of the abnormally warm conditions in the equatorial Pacific Ocean since spring 2014. Owing to the impacts of this strong event, along with climate warming background, the global surface temperature and the surface air temperature over Chinese mainland reached record highs in 2015. Disastrous weather in various places worldwide have occurred in association with this severe El Niño episode, and summer precipitation has reduced significantly in North China, especially over the bend of the Yellow River, central Inner Mongolia, and the coastal areas surrounding Bohai Bay. Serious drought has occurred in some of the above areas. The El Niño episode reached its peak strength during November-December 2015, when a lower-troposphere anomalous anticyclonic circulation prevailed over the Philippines, bringing about abnormal southerlies and substantially increased precipitation in southeastern China. At the same time, a negative phase of the Eurasia-Pacific teleconnection pattern dominated over the mid-high latitudes, which suppressed northerly winds in North China. These two factors together resulted in high concentrations of fine particulate matter (PM2.5) and frequent haze weather in this region. Currently, this strong El Niño is weakening very rapidly, but its impact on climate will continue in the coming months in some regions, especially in China. 相似文献
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209.
Optimizing industrial structure is an important research object of human-economic geography, and it is also the object of government departments to strengthen macro-control. This has become even greater problem that China has entered the “new normal” in recent years. The study uses a multi-regional input-output model, with linear programming to build an optimal model of industrial structure as well as a model of optimization degree under the energy constraint. The results of the study revealed that: (1) the degree of optimization of industrial structure in Anhui Province is optimal (0.763), while that of Shanxi Province is the lowest (0.662); (2) the degree of optimization of industrial structure is negatively related to energy consumption per unit output value and the proportion of heavy industry; and (3) overall, central China should maintain or moderately increase the proportions of resource-based industry, greatly increase the proportions of manufacturing, including transport and telecommunications equipment, computers and other electronic equipment, and moderately reduce the proportions of smelting and pressing of metals and non-metal mineral products. In terms of service industries, the region should greatly increase the proportions of the production and supply of natural gas and tap water, moderately reduce or maintain the proportions of transport and storage as well as tourism, and maintain or moderately reduce the proportions of wholesale trade, retail trade and catering services. 相似文献
210.
基于主体功能区规划的中国城乡建设用地扩张时空特征遥感分析 总被引:17,自引:4,他引:13
21世纪以来,随着中国社会经济的快速发展,城乡建设用地不断扩张,对社会经济和生态环境造成了一系列影响.为了国家可持续发展目标的实现,必须对国土开发空间布局做出科学的规划.为此,一些学者开展了国家主体功能区规划方案研究,其研究成果支持了国家主体功能区规划的制定,该规划于2010年底颁布实施.为分析各类主体功能区在规划颁布前后城乡建设用地变化的特征,评估规划对区域开发的指导作用,及时发现规划实施中的问题,有必要采取有效手段对不同类型主体功能区的国土开发活动进行监测和评估.为此,本研究团队在已完成的2000年和2010年两期全国土地利用变化数据库的基础上,更新了2013年全国土地利用数据库,生成分期的城乡建设用地空间数据集;并对国家尺度各类主体功能区,以及东部,中部,西部,东北4大区域在主体功能区规划颁布前10年间(2000-2010年)和后3年内(2010-2013年)城乡建设用地扩张特征与差异进行了对比分析.结果表明:① 总体而言,2013年优化开发区,重点开发区,农产品主产区和重点生态功能区城乡建设用地在该类主体功能区国土面积中的占比明显不同,体现了国土开发按照不同主体功能布局的梯级特征.② 与2000-2010年相比,2010-2013年优化开发区城乡建设用地年增长率明显降低,重点开发区,农产品主产区和重点生态功能区建设用地年增长率均大幅增加;其中重点开发区和农产品主产区的城乡建设用地年均扩张面积已经超过了优化开发区;重点生态功能区城乡建设用地年均扩张面积和动态度仍处于最低的水平.③ 在区域尺度,优化开发区中,长江三角洲地区建设用地年均增量明显高于其他优化开发区;重点开发区中,西部地区在年增加面积和增加速率两方面均高于其他区域;农产品主产区中,东部,中部和西部地区内城乡建设用地年增加面积均超过前10年的2倍,西部地区的年增加速率更是达到前10年的3倍以上;重点生态功能区中,中部地区城乡建设用地的年变化率和动态度的增长均最为显著.④ 2010-2013年中国城乡建设用地扩张的空间格局和变化特征,在总体上体现了主体功能区规划的梯级开发特征.但是,局部优化开发区,农产品主产区和重点生态功能区建设用地的扩张速度过快,必须切实加强空间管控.研究表明,采用空间格局变化的分析方法,开展主体功能区规划颁布前后两个时期城乡建设用地扩张特征与分阶段区域差异的分析,清晰刻画出不同功能区和不同地区建设用地变化规律及其与主体功能区规划的契合程度,证明了该分析方法的有效性,可据此为未来国土开发空间格局的优化和城乡建设发展提供科学依据. 相似文献