排序方式: 共有38条查询结果,搜索用时 640 毫秒
31.
博州雷暴的时间变化和周期 总被引:4,自引:0,他引:4
利用1961--2000年博州4个气象站雷暴天气的观测资料,分析了雷暴的气候特征.分析表明,博州多年年雷暴日数20-52d,年雷暴日数平原地区较少,高山地区较多,雷暴天气集中出现在夏半年5-8月.温泉雷暴天气的高发时段15-21时,精河高发时段17-23时,阿拉山口高发时段16-24时.温泉、精河和阿拉山口雷暴持续时间以30min为主.博乐和阿拉山口40a内年雷暴日数线性减少,两站年雷暴日数在1979年发生突变.博州雷暴日数年际变化具有6~9a的震荡周期. 相似文献
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A multifunctional HTDMA system with a robust temperature control 总被引:3,自引:0,他引:3
The hygroscopicity of atmospheric aerosols significantly influences their size distribution,
cloud condensation nuclei ability, atmospheric residence time, and climate forcing. In order to investigate
the hygroscopic behavior of aerosol particles and serious haze in China, a Hygroscopic Tandem Differential
Mobility Analyzers (HTDMA) system was designed and constructed at Fudan University. It can function as a
scanning mobility particle sizing system to measure particle size distribution in the range of 20--1000 nm
in diameter, as well as a hygroscopicity analyzer for aerosol particles with diameters between 20--400 nm
in the range of 20%--90% RH (relative humidity). It can also measure the effect of uptake of inorganic acids
or semi-VOCs on the hygroscopic behavior of aerosols, such as typical inorganic salts in atmospheric dust or
their mixtures. The performance tests show that the system measured particle size of the standard polystyrene
latex spheres (PSLs) is 197 nm, which is in excellent agreement with the certified diameter D=199±6 nm, as
well as a standard deviation of the repeated runs SD=8.9x10-4. In addition, the measured hygroscopic
growth factors of the model compounds, (NH4)2SO4 and NaNO3, agree with the Kohler theoretical
curves. The results indicate that the HTDMA system is an excellent and powerful tool for studying the
hygroscopic behavior of submicron aerosols and meets the demand required for laboratory research and
fieldwork on atmospheric aerosols in China. 相似文献
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接地电阻是表示接地体泄放雷电流及其它杂散电流能力的一个物理量.接地电阻的测量在防雷工作中占据很重要的位置,它不仅是衡量接地网质量的重要指标,而且通过测量接地电阻可以判断构筑物、设备的等电位连接等防雷措施的落实情况.测量的数据正确与否直接影响到防雷设施能否有效发挥作用.本文作者根据几年来的工作实践,结合常用检测仪表的工作原理,对检测工作中遇到异常现象进行分析,在此基础上提出了作好检测工作的方法. 相似文献
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一直以来,VisualC++统治着Windows平台上系统级应用软件的开发,随着最新版VisualBasic5.0(VB5.0)的推出,使一度领先的VisualC+-t-、DelPhi2.0相形见细,也预示着VB将成为快速应用开发(RAD)的最快速、最易用、最强劲的开发工具,是企业级客户/服务器应用软件开发的首选工具之一。VB5.0除了提供P代码编译器外,还提供了与VisualC+十相同的32位最优后端本地代码编译器,从而使生成的可执行文件的执行效率有了一个质的飞跃,为开发图形图像显示系统提供了一个轻松、高效的开发环境。lffi形用户界面设计VB本身是一种… 相似文献
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由于低的 摘 图像对比度、不可预测的前列腺位置和不确定的肠道气体,CT图像中自动和准确的前列腺分割是一个具有挑战性的问题。本文提出了一个基于随机森林的前列腺分割方法。利用自动上下文模型训练一系列的随机森林分类器,然后迭代地把这些训练好的分类器应用在测试图像上以改进前列腺的分类结果。实验结果表明,相比于其他最新方法,我们的方法性能更好。 相似文献
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