The latest research shows that the ions generated by the corona discharge of lightning rod have dual functions of attracting and shielding lightning discharge. After the lightning rod is installed at a certain height ...The latest research shows that the ions generated by the corona discharge of lightning rod have dual functions of attracting and shielding lightning discharge. After the lightning rod is installed at a certain height on the ground,the lightning rod tip reaches the corona threshold to ionize the surrounding air and generate positive and negative ions under the action of the electric field at the end of the lightning downward leader. Constrained by Coulomb’s Law,its positive ions( opposite charges attract each other) form an upward leader( streamer),which moves towards the end of the lightning downward leader and is connected to the downward leader,establishing a discharge channel to attract lightning to the needle tip and discharge the current to the ground,and playing a role in attracting lightning. Its negative ions are repelled by the electric field at the end of the lightning downward leader( repelled by isotropic charges) and influenced by the wind,and diffuse in the downwind area to form an ion cloud,inhibiting the growth of corona at the tip of ground objects,and playing a role in shielding lightning. In this paper,Franklin’s understanding of the role of lightning rod and Yang Shaojie’s new definition of the working principle of lightning rod are briefly introduced. The formation mechanism,distribution characteristics,shielding effect,and impact on lightning strike point distribution of ion clouds are analyzed. Additionally,the important role of shielding effects of ion clouds in regional lightning protection is introduced,which provides a theoretical basis for the correct understanding and use of lightning rod.展开更多
针对经典ICP(iterative closest point)算法迭代速度慢、存在误配准点对、鲁棒性不强的问题,利用距离约束函数、kd-tree加速迭代以及CPC(closest point crirterion)三约束方法对算法进行改进。首先利用点到最近三点组成的面的垂足作为...针对经典ICP(iterative closest point)算法迭代速度慢、存在误配准点对、鲁棒性不强的问题,利用距离约束函数、kd-tree加速迭代以及CPC(closest point crirterion)三约束方法对算法进行改进。首先利用点到最近三点组成的面的垂足作为最近点,对算法进行了分类约束改进,剔除了点落在面外造成虚假配准的情况,从而提高迭代精度;然后通过kd-tree算法加速搜索点对过程,减少算法的运行时间;最后通过对CPC中存在的几何约束对配准点集进行错误点对剔除,增强了自动配准技术的鲁棒性和抗噪声能力。实验结果表明,与经典ICP算法相比,改进后的ICP算法在配准精度和时间上有所提高,而且能够有效剔除部分误配准点对,增强了算法的鲁棒性。展开更多
基金Supported by Technology Research and Development Project of Strong Electromagnetic Pulse Protection (Lightning) of Sea Wind Field in Guangdong Yuedian Zhuhai Biqing Bay (YJW-PK23010)。
文摘The latest research shows that the ions generated by the corona discharge of lightning rod have dual functions of attracting and shielding lightning discharge. After the lightning rod is installed at a certain height on the ground,the lightning rod tip reaches the corona threshold to ionize the surrounding air and generate positive and negative ions under the action of the electric field at the end of the lightning downward leader. Constrained by Coulomb’s Law,its positive ions( opposite charges attract each other) form an upward leader( streamer),which moves towards the end of the lightning downward leader and is connected to the downward leader,establishing a discharge channel to attract lightning to the needle tip and discharge the current to the ground,and playing a role in attracting lightning. Its negative ions are repelled by the electric field at the end of the lightning downward leader( repelled by isotropic charges) and influenced by the wind,and diffuse in the downwind area to form an ion cloud,inhibiting the growth of corona at the tip of ground objects,and playing a role in shielding lightning. In this paper,Franklin’s understanding of the role of lightning rod and Yang Shaojie’s new definition of the working principle of lightning rod are briefly introduced. The formation mechanism,distribution characteristics,shielding effect,and impact on lightning strike point distribution of ion clouds are analyzed. Additionally,the important role of shielding effects of ion clouds in regional lightning protection is introduced,which provides a theoretical basis for the correct understanding and use of lightning rod.
文摘针对经典ICP(iterative closest point)算法迭代速度慢、存在误配准点对、鲁棒性不强的问题,利用距离约束函数、kd-tree加速迭代以及CPC(closest point crirterion)三约束方法对算法进行改进。首先利用点到最近三点组成的面的垂足作为最近点,对算法进行了分类约束改进,剔除了点落在面外造成虚假配准的情况,从而提高迭代精度;然后通过kd-tree算法加速搜索点对过程,减少算法的运行时间;最后通过对CPC中存在的几何约束对配准点集进行错误点对剔除,增强了自动配准技术的鲁棒性和抗噪声能力。实验结果表明,与经典ICP算法相比,改进后的ICP算法在配准精度和时间上有所提高,而且能够有效剔除部分误配准点对,增强了算法的鲁棒性。
