Multi-temporal Interferometric Synthetic Aperture Radar(MT-InSAR) is one of the most powerful Earth observation techniques, especially useful for measuring highly detailed ground deformation over large ground areas. M...Multi-temporal Interferometric Synthetic Aperture Radar(MT-InSAR) is one of the most powerful Earth observation techniques, especially useful for measuring highly detailed ground deformation over large ground areas. Much research has been carried out to apply MT-InSAR to monitor ground and infrastructure deformation in urban areas related to land reclamation, underground construction and groundwater extraction.This paper reviews the progress in the research and identifies challenges in applying the technology, including the inconsistency in coherent point identification when different approaches are used, the reliability issue in parameter estimation, difficulty in accurate geolocation of measured points, the one-dimensional line-of-sight nature of InSAR measurements, the inability of making complete measurements over an area due to geometric distortions, especially the shadowing effects, the challenges in processing large SAR datasets, the decrease of the number of coherent points with the increase of the length of SAR time series, and the difficulty in quality control of MT-InSAR results.展开更多
高速列车载客量大、运行时间长,通风系统的优化设计对于提高乘车舒适性和客室空气品质具有重要意义.基于计算流体动力学理论(CFD),建立了满载工况的全尺寸车厢模型.以客室顶部中间送风为例,针对两端排风、下端排风、上端排风以及改变两...高速列车载客量大、运行时间长,通风系统的优化设计对于提高乘车舒适性和客室空气品质具有重要意义.基于计算流体动力学理论(CFD),建立了满载工况的全尺寸车厢模型.以客室顶部中间送风为例,针对两端排风、下端排风、上端排风以及改变两侧排风流量比的上端排风,对比分析了客室内的流场结构以及呼吸污染物扩散特性.采用不均匀系数、能量利用系数、通风效率指标进行评价分析.结果表明,采用改进后的上端排风方式时,客室内的综合评价指标最优,室内平均浓度不足500 ppm(parts per million),稀释倍数超过10000倍.当乘客与污染源向前间隔超过两排或者向后间隔超过一排时,污染物浓度降低至500 ppm以下,可以有效控制前后扩散距离.根据污染物扩散规律,为进一步阻止乘客之间的交叉传播,应避免第B列与第C列乘客相邻乘坐.展开更多
基金The National Natural Science Foundation of China(41774023)The Research Grants Council(RGC)of Hong Kong(PolyU152232/17E,PolyU152164/18E),The Faculty of Construction and Environment(ZZGD)+1 种基金The Research Institute for Sustainable Urban Development(RISUD)(1-BBWB)The TerraSAR-X Science plan(GEO3603)。
文摘Multi-temporal Interferometric Synthetic Aperture Radar(MT-InSAR) is one of the most powerful Earth observation techniques, especially useful for measuring highly detailed ground deformation over large ground areas. Much research has been carried out to apply MT-InSAR to monitor ground and infrastructure deformation in urban areas related to land reclamation, underground construction and groundwater extraction.This paper reviews the progress in the research and identifies challenges in applying the technology, including the inconsistency in coherent point identification when different approaches are used, the reliability issue in parameter estimation, difficulty in accurate geolocation of measured points, the one-dimensional line-of-sight nature of InSAR measurements, the inability of making complete measurements over an area due to geometric distortions, especially the shadowing effects, the challenges in processing large SAR datasets, the decrease of the number of coherent points with the increase of the length of SAR time series, and the difficulty in quality control of MT-InSAR results.
文摘高速列车载客量大、运行时间长,通风系统的优化设计对于提高乘车舒适性和客室空气品质具有重要意义.基于计算流体动力学理论(CFD),建立了满载工况的全尺寸车厢模型.以客室顶部中间送风为例,针对两端排风、下端排风、上端排风以及改变两侧排风流量比的上端排风,对比分析了客室内的流场结构以及呼吸污染物扩散特性.采用不均匀系数、能量利用系数、通风效率指标进行评价分析.结果表明,采用改进后的上端排风方式时,客室内的综合评价指标最优,室内平均浓度不足500 ppm(parts per million),稀释倍数超过10000倍.当乘客与污染源向前间隔超过两排或者向后间隔超过一排时,污染物浓度降低至500 ppm以下,可以有效控制前后扩散距离.根据污染物扩散规律,为进一步阻止乘客之间的交叉传播,应避免第B列与第C列乘客相邻乘坐.
