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相对欧氏距离坐标转换误差评价方法的无效性证明
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作者 谭启蒙 孙沂昆 +1 位作者 胡成威 高升 《机械设计与制造》 北大核心 2014年第7期145-148,共4页
针对机械部件数字化对接过程中广泛涉及的坐标转换问题,定义了两种坐标转换误差评价模型:转换点集-转换点集误差模型和转换点集-测试点集误差模型;详细分析了坐标值误差法、均方根误差法和相对欧氏距离误差法等3种误差评价方法,并利用... 针对机械部件数字化对接过程中广泛涉及的坐标转换问题,定义了两种坐标转换误差评价模型:转换点集-转换点集误差模型和转换点集-测试点集误差模型;详细分析了坐标值误差法、均方根误差法和相对欧氏距离误差法等3种误差评价方法,并利用理论推导与计算机仿真实验证明相对欧氏距离误差法对于转换点集-测试点集误差模型的无效情况:即一旦测试点集位置固定,无论转换点集发生怎样的变化,相对欧氏距离误差参数值始终为一固定常数。 展开更多
关键词 坐标转换 误差评价模型 坐标值误差 均方根误差 相对欧氏距离误差
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Research of the Thermal Parameters and the Accuracy of Flow Measurement of the Biological Fuel
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作者 Igor Korobiichuk Shavursky Yurij +1 位作者 Michal Nowicki Roman Szewczyk 《Journal of Mechanics Engineering and Automation》 2015年第7期415-419,共5页
The heat parameters, the thermoanemometric flow-meter (TAF) errors and the experimental characteristics have been defined. The results of experiments were conducted with the help of physically-informational models a... The heat parameters, the thermoanemometric flow-meter (TAF) errors and the experimental characteristics have been defined. The results of experiments were conducted with the help of physically-informational models allowing to realize all major thermal methods and their inherent informative options. The metrological evaluation was made and the sensitivity to the consumption of gas and liquid have been defined, their static and dynamic errors, followed by the comparison of costs according to these criteria. The developed method provides accurate measurement of volumetric flow of motor fuel 1.0-1.5% at heater temperature measurement accuracy of 1%. 展开更多
关键词 Thermoanemometric flow-meter biological fuel physically-informational models
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Evaluation and intercomparison of ozone simulations by Models-3/CMAQ and CAMx over the Pearl River Delta 被引量:20
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作者 SHEN Jin WANG XueSong +2 位作者 LI JinFeng LI YunPeng ZHANG YuanHang 《Science China Chemistry》 SCIE EI CAS 2011年第11期1789-1800,共12页
Ozone pollution over the Pearl River Delta (PRD) in October 2004 has been simulated using the regional air quality models Models-3/CMAQ and CAMx. The results from both models were evaluated and compared with the obser... Ozone pollution over the Pearl River Delta (PRD) in October 2004 has been simulated using the regional air quality models Models-3/CMAQ and CAMx. The results from both models were evaluated and compared with the observed concentrations from 12 monitoring stations. By integrated process rate analysis, the influences of different physical and chemical processes were quantified, and the causes of the deviations between the two models were investigated. Both CMAQ and CAMx repro- duced the magnitudes and variations of ozone at most stations over the PRD. The correlation coefficients (R) between the sim- ulated results and monitoring data were 0.73 for CMAQ and 0.74 for CAMx. The normalized mean bias (NMB) for CMAQ and CAMx over the 12 sites was ?8.5% and 8.8% on average, respectively. The normalized mean error (NME) for CMAQ and CAMx was 36.7% and 37.9%, respectively. The correlation between the results of two models was very high (R = 0.92), and their simulated ozone spatial distributions exhibited common features. But the values obtained using CMAQ simulation were about 17% lower than those obtained using CAMx on average. The results of simulations using the two models were not identical in certain regions, or for different types of monitoring stations. The differences in dry deposition, reaction parameters and vertical transport near the Pearl River Estuary can account for the discrepancies in the results obtained using the two models. In the upwind areas, the discrepancy in the boundary concentration of the finest nest was the main cause of the higher values obtained using CAMx compared with those obtained using CMAQ. There is a need for CAMx to provide more choices of dry deposition algo- rithms. Improvement of the calculation methods for photolysis rates would also improve the ozone simulation of CMAQ. 展开更多
关键词 Pearl River Delta CMAQ CAMx OZONE process analysis
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