The structure of a high-speed maglev guideway is taken as the research object.With the aim of identifying the inconsistency of modal parameters between the simulation model and the actual model,and based on the 600 km...The structure of a high-speed maglev guideway is taken as the research object.With the aim of identifying the inconsistency of modal parameters between the simulation model and the actual model,and based on the 600 km/h high-speed maglev vehicle and the high-speed maglev test line,the arrangement of sensors and the vibration acceleration data collection of the 12.384 m concrete guideway were conducted.The modal parameters were identified from the guideway response signal using wavelet transform,after which the wavelet ridge was extracted by using the maximum slope method.Next,the vibration modes and frequency parameters of the interaction vibration characteristics of the high-speed maglev guideway and 600 km/h maglev vehicle were analyzed.The updating objective function for the finite element model of the guideway was established,and the initial guideway finite element model was modified and updated by repeatedly iterating the parameters.In doing so,the model structure of the high-speed maglev guideway was obtained,which is consistent with the actual structure.The accuracy of the updated guideway model in the calculation of the dynamic response was verified by combining this with the vehicle-guideway coupling dynamic model of the high-speed maglev system with 18 degrees of freedom.The research results reveal that the model update method based on the wavelet transform and the maximum slope method has the characteristics of high accuracy and fast recognition speed.This can effectively obtain an accurate guideway model that ensures the correctness of the vehicle-guideway coupling dynamic analysis and calculation while meeting the parameters of the measured structure model.This method is also suitable for updating other structural models of high-speed maglev systems.展开更多
选用对数去除率(log-reduction,LR)坐标研究非医疗保健产品菌落总数的辐照灭菌剂量设定问题。以具有标准抗性分布(Standard distribution of resistances,SDR)的菌落总数为研究对象,选择剂量范围从0-1至0-20k Gy,剂量间隔从1至10 k Gy的...选用对数去除率(log-reduction,LR)坐标研究非医疗保健产品菌落总数的辐照灭菌剂量设定问题。以具有标准抗性分布(Standard distribution of resistances,SDR)的菌落总数为研究对象,选择剂量范围从0-1至0-20k Gy,剂量间隔从1至10 k Gy的共56种实验剂量点选取方案,按照传统方法拟合出每个实验方案下的菌落总数"D10值",并计算出LR坐标下相应的灭菌剂量曲线。计算结果表明,传统线性拟合"D10值"法设定菌落总数灭菌剂量的有效范围为LR≤LRmax,其中LRmax为增量剂量实验中最大剂量点Dmax对应的LR值。在此有效范围内,采用最大剂量斜率Dmax/LRmax设定的菌落总数灭菌剂量比传统线性拟合"D10值"法设定的灭菌剂量更接近理论值。最大剂量斜率法与传统方法相比可以大大减少实验次数,并且所设定的菌落总数灭菌剂量更加准确,可以减少不必要的过量辐照,是对传统方法的一大改进。展开更多
针对起伏地形环境下求解民航地空甚高频(very high frequency,VHF)通信有效覆盖范围冗余较大、精度较低的问题,采用改进的最大斜率法进行了仿真研究。首先,考虑遮蔽角计算存在计算冗余,提出“高程清洗”方法,降低计算量。其次,考虑求解...针对起伏地形环境下求解民航地空甚高频(very high frequency,VHF)通信有效覆盖范围冗余较大、精度较低的问题,采用改进的最大斜率法进行了仿真研究。首先,考虑遮蔽角计算存在计算冗余,提出“高程清洗”方法,降低计算量。其次,考虑求解最大斜率遮蔽角存在误差,采用改进的反距离加权插值法对原始数字高程模型数据进行插值提升分辨率,提高了切点逼近点位置精度。然后,为确定遮蔽区域具体点位,提出“切点截止法”进行求解。最后,为得到准确覆盖率,采用“网格法”分析计算。实验表明,改进的最大斜率法可有效减少计算冗余,提高信号覆盖求解精度,覆盖率相对改进前分别降低9.58%、4.10%和1.26‰。改进的VHF有效覆盖范围仿真程序可为VHF地面通信站选址、飞机航线规划提供支撑。展开更多
基金The National 13th Five-Year Science and Technology Support Program of China(No.2016YFB1200602).
文摘The structure of a high-speed maglev guideway is taken as the research object.With the aim of identifying the inconsistency of modal parameters between the simulation model and the actual model,and based on the 600 km/h high-speed maglev vehicle and the high-speed maglev test line,the arrangement of sensors and the vibration acceleration data collection of the 12.384 m concrete guideway were conducted.The modal parameters were identified from the guideway response signal using wavelet transform,after which the wavelet ridge was extracted by using the maximum slope method.Next,the vibration modes and frequency parameters of the interaction vibration characteristics of the high-speed maglev guideway and 600 km/h maglev vehicle were analyzed.The updating objective function for the finite element model of the guideway was established,and the initial guideway finite element model was modified and updated by repeatedly iterating the parameters.In doing so,the model structure of the high-speed maglev guideway was obtained,which is consistent with the actual structure.The accuracy of the updated guideway model in the calculation of the dynamic response was verified by combining this with the vehicle-guideway coupling dynamic model of the high-speed maglev system with 18 degrees of freedom.The research results reveal that the model update method based on the wavelet transform and the maximum slope method has the characteristics of high accuracy and fast recognition speed.This can effectively obtain an accurate guideway model that ensures the correctness of the vehicle-guideway coupling dynamic analysis and calculation while meeting the parameters of the measured structure model.This method is also suitable for updating other structural models of high-speed maglev systems.
文摘选用对数去除率(log-reduction,LR)坐标研究非医疗保健产品菌落总数的辐照灭菌剂量设定问题。以具有标准抗性分布(Standard distribution of resistances,SDR)的菌落总数为研究对象,选择剂量范围从0-1至0-20k Gy,剂量间隔从1至10 k Gy的共56种实验剂量点选取方案,按照传统方法拟合出每个实验方案下的菌落总数"D10值",并计算出LR坐标下相应的灭菌剂量曲线。计算结果表明,传统线性拟合"D10值"法设定菌落总数灭菌剂量的有效范围为LR≤LRmax,其中LRmax为增量剂量实验中最大剂量点Dmax对应的LR值。在此有效范围内,采用最大剂量斜率Dmax/LRmax设定的菌落总数灭菌剂量比传统线性拟合"D10值"法设定的灭菌剂量更接近理论值。最大剂量斜率法与传统方法相比可以大大减少实验次数,并且所设定的菌落总数灭菌剂量更加准确,可以减少不必要的过量辐照,是对传统方法的一大改进。
文摘针对起伏地形环境下求解民航地空甚高频(very high frequency,VHF)通信有效覆盖范围冗余较大、精度较低的问题,采用改进的最大斜率法进行了仿真研究。首先,考虑遮蔽角计算存在计算冗余,提出“高程清洗”方法,降低计算量。其次,考虑求解最大斜率遮蔽角存在误差,采用改进的反距离加权插值法对原始数字高程模型数据进行插值提升分辨率,提高了切点逼近点位置精度。然后,为确定遮蔽区域具体点位,提出“切点截止法”进行求解。最后,为得到准确覆盖率,采用“网格法”分析计算。实验表明,改进的最大斜率法可有效减少计算冗余,提高信号覆盖求解精度,覆盖率相对改进前分别降低9.58%、4.10%和1.26‰。改进的VHF有效覆盖范围仿真程序可为VHF地面通信站选址、飞机航线规划提供支撑。
