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基于气动力数据集的气动偏差建模与辨识 被引量:1
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作者 曹德一 张翔 张元静 《战术导弹技术》 北大核心 2021年第3期7-13,共7页
针对飞行器采用离散数据进行气动力建模的辨识需求,发展了一种基于气动力数据集的气动偏差建模与辨识方法。该方法利用离散数据可高效描述气动力非线性变化的特点,采用依据极大似然准则的牛顿-拉夫逊法,将气动力数据集与真实气动力的偏... 针对飞行器采用离散数据进行气动力建模的辨识需求,发展了一种基于气动力数据集的气动偏差建模与辨识方法。该方法利用离散数据可高效描述气动力非线性变化的特点,采用依据极大似然准则的牛顿-拉夫逊法,将气动力数据集与真实气动力的偏差作为辨识对象,利用线性模型进行气动偏差建模与辨识,避免了传统多项式气动力模型在辨识非线性气动力时参数过多、不便对离散气动力数据修正等问题。通过仿真飞行试验,对比了飞行器受扰动激励后的辨识拟合弹道与飞行仿真弹道,并进行了全局攻角下的飞行器阻力系数、升力系数和俯仰力矩系数辨识修正结果和真实值的对比。结果表明:辨识拟合弹道与真实飞行弹道基本重合,辨识修正后的气动力与真实值吻合较好,所建立的方法是正确、有效的,具有良好的实用性。 展开更多
关键词 气动力数据集 气动力偏差 建模与辨识 极大似然方法
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An assessment of summer sensible heat flux on the Tibetan Plateau from eight data sets 被引量:25
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作者 ZHU XiaYing LIU YiMin WU GuoXiong 《Science China Earth Sciences》 SCIE EI CAS 2012年第5期779-786,共8页
The eight datasets of the summer (June-August) surface sensible heat (SH) flux over the Tibetan Plateau (TP) are compared on the time scales of the climatology,interannual variability and linear trend during 1980-2006... The eight datasets of the summer (June-August) surface sensible heat (SH) flux over the Tibetan Plateau (TP) are compared on the time scales of the climatology,interannual variability and linear trend during 1980-2006.These data sets include five reanalyses (National Center for Environmental Prediction reanalysis,NCEPR1 and NCEPR2,NCEP climate forecast system reanalysis,CFSR,Japanese 25-year reanalysis,JRA,and European Centre for Medium Range Weather Forecasts reanalysis,ERA40),two land surface model outputs (Noah model data of Global Land Data Assimilation System version 2,G2_Noah,and Simple Biosphere version 2 output by Yang et al.,YSiB2),and estimated SH based on China Meteorological Administration (CMA) station observations,ObCh.The results suggest that the summer SH on the TP differs from one dataset to another due to different inputs and calculations.Climatologically,the ERA40 and JRA distribute rather uniformly while the other six products show similar regional disparities,that is,larger in the west than in the east and stronger in the north and the south than in the middle of the plateau.The mean magnitude of the SH averaged over the 76 stations above the TP varies considerably among each dataset with the difference of more than 20 W m?2 between the maximum (G2_Noah) and minimum (ObCh).Nevertheless,they are consistent in the interannual variability and mostly show a significant decreasing trend corresponding to the weakening surface wind speed,in spite of the distinct trend for the ground-air temperature difference among the different data sets.These two consistencies indicate the particular availability of the SH products,which is helpful to the relevant climate dynamics research. 展开更多
关键词 Tibetan Plateau sensible heat flux assessment interannual variation linear trend
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