Using geographic information system to study flooded area and damage evaluation has been a hotspot in environmental disaster research for years. In this paper, a model for flooded area calculation and damage evaluatio...Using geographic information system to study flooded area and damage evaluation has been a hotspot in environmental disaster research for years. In this paper, a model for flooded area calculation and damage evaluation is presented. Flooding is divided into two types: ‘soruce flood’ and ‘non-source flood’. The source-flood area calculation is based on seed spread algorithm. The flood damage evaluation is calculated by overlaying the flooded ara range with thematic maps and relating the results to other social and economic data. To raise the operational efficiency of the model, a skipping approach is used to speed seed spread algorithm and all thematic maps are converted to raster format before overlay analysis. The accuracy of flooded area calculation and damage evaluation is mainly dependent upon the resolution and precision of the digital elevation model (DEM) data, upon the accuracy of registering all raster layers, and upon the quality of economic information. This model has been successfully used in the Zhejiang Province Comprehensive Water Management Information System developed by the authors. The applications show that this model is especially useful for most counties of China and other developing countries.展开更多
A practical approach of measurement calibration is presented for obtaining the true area of the photographed objects projected in the 2-D image scene. The calibration is performed using three circular samples with giv...A practical approach of measurement calibration is presented for obtaining the true area of the photographed objects projected in the 2-D image scene. The calibration is performed using three circular samples with given diameters. The process is first to obtain the ratio mm/pixel in two orthogonal directions, and then use the obtained ratios with the total number of pixels scanned within projected area of the object of interest to compute the desired area. Compared the optically measured areas with their corresponding true areas, the results show that the proposed method is quite encouraging and the relevant application also proves the approach adequately accurate.展开更多
This paper provides a calculating method which can be used in calculation of the kill probability attack area for every AAM. At first, attack area of AAM and kill probability of every characteristic point are obtained...This paper provides a calculating method which can be used in calculation of the kill probability attack area for every AAM. At first, attack area of AAM and kill probability of every characteristic point are obtained by combining trajectory calculation with kill probability calculation. Then, coordinates of a fire point relative to standard kill probability value in terms of standardization method are found. At last, equivalent kill probability curve equations are formulated by means of curve fitting method.展开更多
Through on-site defect investigation,special inspection,and finite element simulation calculation of a high-speed upper-span(30+32+30)m prestressed concrete box girder bridge,the overall sliding force of the bridge on...Through on-site defect investigation,special inspection,and finite element simulation calculation of a high-speed upper-span(30+32+30)m prestressed concrete box girder bridge,the overall sliding force of the bridge on the right side of platform 0#is analyzed.In this situation,typical defects such as overall girder slippage,support dislocation,pier column deviation,and pier bottom side cracks have occurred in the overpass.At the same time,combined with simulation calculation analysis,it is interpreted that the 0#and 1#foundation has been damaged at a certain position below the ground line.The occurrence of broken piles has provided a reliable basis for the later reinforcement and maintenance of the bridge and ideas for emergency inspection and analysis of bridges damaged by the same type of landslides.展开更多
在轴向柱塞泵的工作过程中,通过配流盘进行高低压的循环切换,而配流盘的过流面积是影响柱塞泵内部压力平稳过渡的重要参数。为了完成对配流结构过流面积的求解计算,提出了一种基于多维流场点云的过流面积计算方法。首先,对配流盘流场的...在轴向柱塞泵的工作过程中,通过配流盘进行高低压的循环切换,而配流盘的过流面积是影响柱塞泵内部压力平稳过渡的重要参数。为了完成对配流结构过流面积的求解计算,提出了一种基于多维流场点云的过流面积计算方法。首先,对配流盘流场的点云化过程进行了理论分析,得到了点云化处理的实施方法;然后,对配流盘三维流域模型进行了系列修正,提出了缓冲槽连通阶段模型的修正方法,提高了过流面积计算的准确性;最后,对不同配流阶段的过流面积进行了计算,并与理论测量所得结果以及采用计算流体力学(CFD)数值模拟方法所得的结果,分别进行了对比。计算结果表明:基于多维流场点云的过流面积识别算法求得的过流面积峰值大小为174.5 mm 2,而理论测量值的大小为177.5 mm 2;二者的相对误差率大约为1.7%;而与基于CFD方法所得结果的整体相对误差率,大约在5%以内。研究结果表明:采用该方法,能够直接且较精准地完成对配流盘过流面积的求解与计算,有效地简化了过流面积变换趋势的求解过程。展开更多
基金Project of National Ninth Five-Year Plan, 96-D042
文摘Using geographic information system to study flooded area and damage evaluation has been a hotspot in environmental disaster research for years. In this paper, a model for flooded area calculation and damage evaluation is presented. Flooding is divided into two types: ‘soruce flood’ and ‘non-source flood’. The source-flood area calculation is based on seed spread algorithm. The flood damage evaluation is calculated by overlaying the flooded ara range with thematic maps and relating the results to other social and economic data. To raise the operational efficiency of the model, a skipping approach is used to speed seed spread algorithm and all thematic maps are converted to raster format before overlay analysis. The accuracy of flooded area calculation and damage evaluation is mainly dependent upon the resolution and precision of the digital elevation model (DEM) data, upon the accuracy of registering all raster layers, and upon the quality of economic information. This model has been successfully used in the Zhejiang Province Comprehensive Water Management Information System developed by the authors. The applications show that this model is especially useful for most counties of China and other developing countries.
基金Supported by the National Natural Science Foundation of China (No.60472100).
文摘A practical approach of measurement calibration is presented for obtaining the true area of the photographed objects projected in the 2-D image scene. The calibration is performed using three circular samples with given diameters. The process is first to obtain the ratio mm/pixel in two orthogonal directions, and then use the obtained ratios with the total number of pixels scanned within projected area of the object of interest to compute the desired area. Compared the optically measured areas with their corresponding true areas, the results show that the proposed method is quite encouraging and the relevant application also proves the approach adequately accurate.
文摘This paper provides a calculating method which can be used in calculation of the kill probability attack area for every AAM. At first, attack area of AAM and kill probability of every characteristic point are obtained by combining trajectory calculation with kill probability calculation. Then, coordinates of a fire point relative to standard kill probability value in terms of standardization method are found. At last, equivalent kill probability curve equations are formulated by means of curve fitting method.
文摘Through on-site defect investigation,special inspection,and finite element simulation calculation of a high-speed upper-span(30+32+30)m prestressed concrete box girder bridge,the overall sliding force of the bridge on the right side of platform 0#is analyzed.In this situation,typical defects such as overall girder slippage,support dislocation,pier column deviation,and pier bottom side cracks have occurred in the overpass.At the same time,combined with simulation calculation analysis,it is interpreted that the 0#and 1#foundation has been damaged at a certain position below the ground line.The occurrence of broken piles has provided a reliable basis for the later reinforcement and maintenance of the bridge and ideas for emergency inspection and analysis of bridges damaged by the same type of landslides.
文摘在轴向柱塞泵的工作过程中,通过配流盘进行高低压的循环切换,而配流盘的过流面积是影响柱塞泵内部压力平稳过渡的重要参数。为了完成对配流结构过流面积的求解计算,提出了一种基于多维流场点云的过流面积计算方法。首先,对配流盘流场的点云化过程进行了理论分析,得到了点云化处理的实施方法;然后,对配流盘三维流域模型进行了系列修正,提出了缓冲槽连通阶段模型的修正方法,提高了过流面积计算的准确性;最后,对不同配流阶段的过流面积进行了计算,并与理论测量所得结果以及采用计算流体力学(CFD)数值模拟方法所得的结果,分别进行了对比。计算结果表明:基于多维流场点云的过流面积识别算法求得的过流面积峰值大小为174.5 mm 2,而理论测量值的大小为177.5 mm 2;二者的相对误差率大约为1.7%;而与基于CFD方法所得结果的整体相对误差率,大约在5%以内。研究结果表明:采用该方法,能够直接且较精准地完成对配流盘过流面积的求解与计算,有效地简化了过流面积变换趋势的求解过程。
