An algorithm was proposed to fast recognize three types of underwater micro-terrain, i.e. the level, the gradient and the uneven. With pendulum single beam bathymeter, the hard level concrete floor, the random uneven ...An algorithm was proposed to fast recognize three types of underwater micro-terrain, i.e. the level, the gradient and the uneven. With pendulum single beam bathymeter, the hard level concrete floor, the random uneven floor and the gradient wood panel (8-) were ultrasonically detected 20 times, respectively. The results show that the algorithm is right from fact that the first clustering values of the uneven are all less than the threshold value of 60.0% that is obtained by the level and gradient samples. The algorithm based on the dynamic clustering theory can effectively eliminate the influences of the exceptional elevation values produced by the disturbances resulted from the grazing angle, the characteristic of bottom material and environmental noises, and its real-time capability is good. Thus, the algorithm provides a foundation for the next restructuring of the micro-terrain.展开更多
目前对均匀覆冰下架空线等值覆冰厚度计算模型的研究较多,但缺少对大截面、大单位长度重量的地线复合光缆(optical pilot ground wire,OPGW)地线覆冰的研究,特别是在微地形下等值冰厚计算模型的适用性。选取大档距大高差工况,通过有限...目前对均匀覆冰下架空线等值覆冰厚度计算模型的研究较多,但缺少对大截面、大单位长度重量的地线复合光缆(optical pilot ground wire,OPGW)地线覆冰的研究,特别是在微地形下等值冰厚计算模型的适用性。选取大档距大高差工况,通过有限元软件建立3种典型地形(山坡、山顶、垭口)下的3塔两档OPGW地线模型,结合考虑绝缘子串偏斜角的等值冰厚模型,对传统输电线路等值覆冰厚度模型进行误差分析,结果发现等值冰厚较小时大档薄覆冰情况下的传统冰厚计算误差较大。但随着平均等值冰厚增大,冰厚计算误差显著减小。利用以上分析结果和平均等值冰厚与绝缘子串轴向拉力与倾角的函数关系,提出一种冰厚误差优化计算方法,改进后的冰厚相对误差能控制在10%以内。展开更多
文章以ArcG IS 9.2为软件平台,以阳江农场1∶50 000地形图为基础生成水平栅格分辨率为25 m的DEM,并提取了部分宏观和微观地形因子进行分析。结果表明,阳江农场属于低海拔地区,主要以平坦地形为主,大部分地区地表粗糙度及高程变异系数较...文章以ArcG IS 9.2为软件平台,以阳江农场1∶50 000地形图为基础生成水平栅格分辨率为25 m的DEM,并提取了部分宏观和微观地形因子进行分析。结果表明,阳江农场属于低海拔地区,主要以平坦地形为主,大部分地区地表粗糙度及高程变异系数较小;大部分土地资源较好,南、北坡向的土地面积略有差异,研究区地表起伏不大,且多为平坡,应注重对地力进行维护,防止水土及养分流失;应进一步研究栅格图最佳分辨率,以提高地形因子分析精度;有必要结合实际调查状况,对相应地貌特征处理结果进行客观分析。展开更多
基金Project(50474052) supported by the National Natural Foundation of China
文摘An algorithm was proposed to fast recognize three types of underwater micro-terrain, i.e. the level, the gradient and the uneven. With pendulum single beam bathymeter, the hard level concrete floor, the random uneven floor and the gradient wood panel (8-) were ultrasonically detected 20 times, respectively. The results show that the algorithm is right from fact that the first clustering values of the uneven are all less than the threshold value of 60.0% that is obtained by the level and gradient samples. The algorithm based on the dynamic clustering theory can effectively eliminate the influences of the exceptional elevation values produced by the disturbances resulted from the grazing angle, the characteristic of bottom material and environmental noises, and its real-time capability is good. Thus, the algorithm provides a foundation for the next restructuring of the micro-terrain.
文摘目前对均匀覆冰下架空线等值覆冰厚度计算模型的研究较多,但缺少对大截面、大单位长度重量的地线复合光缆(optical pilot ground wire,OPGW)地线覆冰的研究,特别是在微地形下等值冰厚计算模型的适用性。选取大档距大高差工况,通过有限元软件建立3种典型地形(山坡、山顶、垭口)下的3塔两档OPGW地线模型,结合考虑绝缘子串偏斜角的等值冰厚模型,对传统输电线路等值覆冰厚度模型进行误差分析,结果发现等值冰厚较小时大档薄覆冰情况下的传统冰厚计算误差较大。但随着平均等值冰厚增大,冰厚计算误差显著减小。利用以上分析结果和平均等值冰厚与绝缘子串轴向拉力与倾角的函数关系,提出一种冰厚误差优化计算方法,改进后的冰厚相对误差能控制在10%以内。
文摘文章以ArcG IS 9.2为软件平台,以阳江农场1∶50 000地形图为基础生成水平栅格分辨率为25 m的DEM,并提取了部分宏观和微观地形因子进行分析。结果表明,阳江农场属于低海拔地区,主要以平坦地形为主,大部分地区地表粗糙度及高程变异系数较小;大部分土地资源较好,南、北坡向的土地面积略有差异,研究区地表起伏不大,且多为平坡,应注重对地力进行维护,防止水土及养分流失;应进一步研究栅格图最佳分辨率,以提高地形因子分析精度;有必要结合实际调查状况,对相应地貌特征处理结果进行客观分析。
