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运用2017—2020年5—8月城市空气质量数据和地面气象数据,筛选出对O3日最大8 h滑动平均质量浓度（以下用C8h(O3)表示）影响较大的气象因子,建立了近地面C8h(O3)主要气象条件判定标准——高质量浓度O3潜势指数（IHPP）,进一步拟合得到汾渭平原夏季C8h(O3)多元逐步回归预报方程,并进行效果检验。结果表明：汾渭平原IHPP由日最高气温（Tmax）、日均相对湿度（HR）、日照时数（t）、日主导风向（WD）和降水量（P）5个气象因子构成,其值介于-1～6之间,值越大则该日近地面O3超标可能性越大;经检验,C8h(O3)多元逐步回归方程预报结果与实况较吻合,汾河平原（特别是运城）预报效果总体较好,临汾、吕梁和西安等级预报效果有待改进;预报检验时段咸阳和晋中等级预报准确率较国家气象中心的指导预报分别上升79%和289%,说明预报方程具有一定的业务应用可行性。 相似文献
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Land bridge transportation means transportation from one seaport to another by railway across continents instead of by ocean ship. At present, there are two common routes for using land bridge transportation in the world. One is Asia-America-Europe land bridge, the other is Europe-Asia land bridge.Eurasia land bridge has obvious advantages over Asia-America-Europe land bridge due to its shorter distance, shorter transportation time and special freight rate. China started Eurasia land bridge transportation business in 1980. It mainly used the mode of railway-railway combined transportation. The comparison between using Eurasia land bridge and using shipping transportation from China to Northern and Western Europe shows that Euraria land bridge transportation can save time and get foreign exchange in time, and commodity turnover will be speeded up. According to the port layout and railway network structure, China's land bridge transportation projects are proposed. They are Suifenhe project, Dalian project 相似文献
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基于小波系数统计特征，提出了一种SAR图像恢复方法。首先将对数变换后的SAR图像进行平稳小波分解，基于小波系数统计特征，用α—stable分布分别对纯净信号和噪声建模，估计出各部分模型参数后，用MAP估计器对处理后的SAR图像进行非线性处理来恢复出纯净图像。实验结果表明，该方法能在抑制噪声的同时最大程度地保持纹理细节。 相似文献
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