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顾及几何形态与密度分布的点云压缩方法 被引量:1
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作者 张少彬 杨必胜 梁福逊 《测绘科学技术》 2018年第3期212-222,共11页
针对传统点云压缩算法中主要应用法向量、曲率等测度来描述目标区域几何信息,易受噪点影响,无法保证压缩精度的问题,提出一种顾及几何形态与密度分布的点云迭代压缩算法。本文首先利用三维高斯核函数对原始点云进行平滑处理,依据点平滑... 针对传统点云压缩算法中主要应用法向量、曲率等测度来描述目标区域几何信息,易受噪点影响,无法保证压缩精度的问题,提出一种顾及几何形态与密度分布的点云迭代压缩算法。本文首先利用三维高斯核函数对原始点云进行平滑处理,依据点平滑前后平坦度变化分量与密度变化分量来衡量当前点在点云中的重要度,然后迭代去除重要度最低的点,并计算该点影响范围点集,更新其重要度,最终实现点云压缩。采用两份数据对本文算法进行验证,并与三种经典压缩方法进行对比,实验表明,相较于其他三种方法,本算法压缩结果在点分布均匀的同时,能够较好的保留特征点集。 展开更多
关键词 点云压缩 高斯核函数 平滑距离 点重要度
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Equilibrium morphology of gas–liquid Janus droplets: A numerical analysis of buoyancy effect 被引量:1
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作者 shaobin zhang Helen Yan +2 位作者 Yuhao Geng Ke Wang Jianhong Xu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第10期2121-2126,共6页
In this article, a theoretical model for predicting the equilibrium morphology of gas–liquid Janus droplets was built. Based on this model, the effects of bubble radius and volume ratio on morphology change was syste... In this article, a theoretical model for predicting the equilibrium morphology of gas–liquid Janus droplets was built. Based on this model, the effects of bubble radius and volume ratio on morphology change was systematically studied. The increase of bubble radius causes the two parts(bubble and oil drop) in Janus droplets tend to merge while the impact of volume ratio is complicated. When volume ratio increases, these two parts firstly tend to merge, then gradually separate. The accuracy of this model was verified by experimental results. 展开更多
关键词 形态学变化 数字分析 微滴 液体 煤气 平衡 模型 比率
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Exploring HONO formation and its role in driving secondary pollutants formation during winter in the North China Plain 被引量:1
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作者 shaobin zhang Guo Li +21 位作者 Nan Ma Yao He Shaowen Zhu Xihao Pan Wenlin Dong Yanyan zhang Qingwei Luo Jeannine Ditas Uwe Kuhn Yuxuan zhang Bin Yuan Zelong Wang Peng Cheng Juan Hong Jiangchuan Tao Wanyun Xu Ye Kuang Qiaoqiao Wang Yele Sun Guangsheng Zhou Yafang Cheng Hang Su 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2023年第10期83-97,共15页
Daytime HONO photolysis is an important source of atmospheric hydroxyl radicals(OH).Knowledge of HONO formation chemistry under typical haze conditions,however,is still limited.In the Multiphase chemistry experiment i... Daytime HONO photolysis is an important source of atmospheric hydroxyl radicals(OH).Knowledge of HONO formation chemistry under typical haze conditions,however,is still limited.In the Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain in 2018,we investigated the wintertime HONO formation and its atmospheric implications at a rural site Gucheng.Three different episodes based on atmospheric aerosol loading levels were classified:clean periods(CPs),moderately polluted periods(MPPs)and severely polluted periods(SPPs).Correlation analysis revealed that HONO formation via heteroge.neous conversion of NO_(2)was more efficient on aerosol surfaces than on ground,highlighting the important role of aerosols in promoting HONO formation.Daytime HONO budget analysis indicated a large missing source(with an average production rate of 0.66±0.26,0.97±0.47 and 1.45±0.55 ppbV/hr for CPs,MPPs and SPPs,respectively),which strongly correlated with photo-enhanced reactions(NO_(2)heterogeneous reaction and particulate nitrate photolysis).Average OH formation derived from HONO photolysis reached up to(0.92±0.71),(1.75±1.26)and(1.82±1.47)ppbV/hr in CPs,MPPs and SPPs respectively,much higher than that from O3 photolysis(i.e.,(0.004±0.004),(0.006±0.007)and(0.0035±0.0034)ppbV/hr).Such high OH production rates could markedly regulate the atmospheric oxidation capacity and hence promote the formation of secondary aerosols and pollutants. 展开更多
关键词 HONO North China Plain Budget analysis OH radicals
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