以三峡库区滑坡灾害多发的巫山-奉节段为研究区,基于InSAR技术提出了一种潜在滑坡早期识别方法。该方法首先选取2017年3月-2018年11月共48景Sentinel-1 A SAR升轨数据,利用永久散射体干涉测量(PS-InSAR)技术提取出相对稳定的散射体作为...以三峡库区滑坡灾害多发的巫山-奉节段为研究区,基于InSAR技术提出了一种潜在滑坡早期识别方法。该方法首先选取2017年3月-2018年11月共48景Sentinel-1 A SAR升轨数据,利用永久散射体干涉测量(PS-InSAR)技术提取出相对稳定的散射体作为地面控制点(GCP),并引入到小基线集干涉测量(SBAS-InSAR)技术流程中获取长时间序列的地表形变信息;然后统计分析该区域历史滑坡的孕灾因子规律,结合区域SAR数据的地形可视性分析筛选出孕育滑坡概率大于50%的形变点,并对这些形变点采用Anselin Local Moran’s I指数进行空间域异常值分析和聚类处理,获得置信水平不低于95%的高异常值区;最后结合区域地形地貌特征和高分辨率光学影像识别出高概率的潜在滑坡范围。该方法具有可行性,可用于指导滑坡灾害预测预警和野外地质灾害的实地调查。展开更多
Snow data collection systems in the western United States were originally designed to forecast water supply and may be subject to several sources of bias. In addition to climate change and weather modification effects...Snow data collection systems in the western United States were originally designed to forecast water supply and may be subject to several sources of bias. In addition to climate change and weather modification effects, site-specific effects may be introduced from vegetation changes, site physical changes, measurement technique, and sensor changes. This paper examines changes in Utah＇s snowpack conditions over the past decade compared with all previous measurement years, focusing on the 15 snow courses with the longest observational record within the state of Utah. Although patterns in snowpack data consistent with those that would be expected due to temperature h as greater declines at lower elevations and latitudes--were not identified, snow water equivalent decreased at sites with significant increases in vegetation coverage. Additionally, we provide a list of 22 snow courses in Utah that are best-suited for long-term climate analysis.展开更多
The velocity area method belongs to the group of primary methods for discharge measurement in hydropower plants. The measurements require an appropriate application of measuring devices and carrying out correctly the ...The velocity area method belongs to the group of primary methods for discharge measurement in hydropower plants. The measurements require an appropriate application of measuring devices and carrying out correctly the process of data analyzing including integration technique. The authors present their own experiences gathered during many years of utilizing the current meter method for discharge measurement in many hydropower plants. They have developed the special integration techniques using the progressive numerical algorithms. The techniques differ from the recommendations contained in the relevant international standards. The authors＇ own software for calculating the discharge from the measured local velocity distribution （obtained using current meters） adopts advanced spline functions, the so-called NURBS （non-uniform rational B-splines）. Nowadays, this kind of splines is commonly used in modeling of the complex geometrical shapes because of their smoothness. It is assessed that it represents much better quality of interpolation than the classic spline functions （classic cubic spline technique）. Particularly, the better properties of the NURBS splines can be observed for velocity profile area characterized by very strong velocity gradients where boundary layers meet the core regions of the flow （mainstream）. In the developed software the boundary layer thickness and exponent of von Karman function is calculated in accordance with the ISO 3354 standard. The software has been successfully used during many performance tests of the hydraulic turbines in Poland for several years. Paper presents the results of flow rate measurements for two different flow systems of Kaplan turbines. First case concerns the application of the current meters in a long circular penstock whereas the second one in short rectangular turbine intake. A comparative analysis of three flow calculation procedures applied for these two cases is presented in the paper-（1） the integration procedure according to the ISO 3354 standard; （2） the integration procedure based on the NS （natural splines）; and （3） the integration procedure based on the NURBS. The results obtained using these three procedures for the first case （intake via long circular penstock） were compared with the results of discharge measurements conducted using the pressure-time method.展开更多
文摘以三峡库区滑坡灾害多发的巫山-奉节段为研究区,基于InSAR技术提出了一种潜在滑坡早期识别方法。该方法首先选取2017年3月-2018年11月共48景Sentinel-1 A SAR升轨数据,利用永久散射体干涉测量(PS-InSAR)技术提取出相对稳定的散射体作为地面控制点(GCP),并引入到小基线集干涉测量(SBAS-InSAR)技术流程中获取长时间序列的地表形变信息;然后统计分析该区域历史滑坡的孕灾因子规律,结合区域SAR数据的地形可视性分析筛选出孕育滑坡概率大于50%的形变点,并对这些形变点采用Anselin Local Moran’s I指数进行空间域异常值分析和聚类处理,获得置信水平不低于95%的高异常值区;最后结合区域地形地貌特征和高分辨率光学影像识别出高概率的潜在滑坡范围。该方法具有可行性,可用于指导滑坡灾害预测预警和野外地质灾害的实地调查。
文摘Snow data collection systems in the western United States were originally designed to forecast water supply and may be subject to several sources of bias. In addition to climate change and weather modification effects, site-specific effects may be introduced from vegetation changes, site physical changes, measurement technique, and sensor changes. This paper examines changes in Utah＇s snowpack conditions over the past decade compared with all previous measurement years, focusing on the 15 snow courses with the longest observational record within the state of Utah. Although patterns in snowpack data consistent with those that would be expected due to temperature h as greater declines at lower elevations and latitudes--were not identified, snow water equivalent decreased at sites with significant increases in vegetation coverage. Additionally, we provide a list of 22 snow courses in Utah that are best-suited for long-term climate analysis.
文摘The velocity area method belongs to the group of primary methods for discharge measurement in hydropower plants. The measurements require an appropriate application of measuring devices and carrying out correctly the process of data analyzing including integration technique. The authors present their own experiences gathered during many years of utilizing the current meter method for discharge measurement in many hydropower plants. They have developed the special integration techniques using the progressive numerical algorithms. The techniques differ from the recommendations contained in the relevant international standards. The authors＇ own software for calculating the discharge from the measured local velocity distribution （obtained using current meters） adopts advanced spline functions, the so-called NURBS （non-uniform rational B-splines）. Nowadays, this kind of splines is commonly used in modeling of the complex geometrical shapes because of their smoothness. It is assessed that it represents much better quality of interpolation than the classic spline functions （classic cubic spline technique）. Particularly, the better properties of the NURBS splines can be observed for velocity profile area characterized by very strong velocity gradients where boundary layers meet the core regions of the flow （mainstream）. In the developed software the boundary layer thickness and exponent of von Karman function is calculated in accordance with the ISO 3354 standard. The software has been successfully used during many performance tests of the hydraulic turbines in Poland for several years. Paper presents the results of flow rate measurements for two different flow systems of Kaplan turbines. First case concerns the application of the current meters in a long circular penstock whereas the second one in short rectangular turbine intake. A comparative analysis of three flow calculation procedures applied for these two cases is presented in the paper-（1） the integration procedure according to the ISO 3354 standard; （2） the integration procedure based on the NS （natural splines）; and （3） the integration procedure based on the NURBS. The results obtained using these three procedures for the first case （intake via long circular penstock） were compared with the results of discharge measurements conducted using the pressure-time method.
