为研究在高速列车场景下车体横向振动对自由空间光(free space optical,FSO)通信指向误差的影响,首先利用TB/T 3352—2014《高速铁路无砟轨道不平顺谱》中的轨向、轨距不平顺功率谱推导出横向合成不平顺谱公式,用谱公式仿真生成横向合...为研究在高速列车场景下车体横向振动对自由空间光(free space optical,FSO)通信指向误差的影响,首先利用TB/T 3352—2014《高速铁路无砟轨道不平顺谱》中的轨向、轨距不平顺功率谱推导出横向合成不平顺谱公式,用谱公式仿真生成横向合成不平顺数据;其次建立1/4车体3自由度横向车体振动模型,使用拉普拉斯变换推导出车体横向振动微分方程组的传递函数,搭建车体振动的Simulink仿真模型,推导车体横向位移的功率谱密度(power spectrum density,PSD),经统计得出仿真车体横向位移的概率密度函数(probability density function,PDF);最后利用车体横向位移PDF推导其导致的指向性误差的PDF。仿真验证了轨道横向合成不平顺谱公式、车体横向位移的PSD和PDF,以及横向位移导致的指向性误差的PDF。本研究获得的指向性误差的PDF可用于高铁FSO通信链路的信道建模和系统性能分析。展开更多
Over recent years,the reform-driven development of education has been one primary idea of the Chinese government under the leadership of Xi Jinping.Above all,the reform of the personnel system,closely related to the i...Over recent years,the reform-driven development of education has been one primary idea of the Chinese government under the leadership of Xi Jinping.Above all,the reform of the personnel system,closely related to the interests of teachers,becomes the most sensitive link in the educational reform.To root out the restriction of education system on teachers and enhance their enthusiasm for work,Jia County carried out a reform of teacher personnel system from 2013 to 2016,including breaking the hierarchical restriction on teachers’administrative promotion,decentralizing the power of confirming the teachers’professional titles,eliminating the teachers with the worst performances,practicing performance salary,and other measures.In this study,we tracked 627 teachers regarding their work enthusiasm and stress during the three-year reform,analyzed the data through the Hierarchical Linear Model(HLM),and found that:(1)The teachers’enthusiasm for work increased over time,but did not significantly change with the consideration of the influence of the principals’leadership in teaching.The personnel system reform aiming at motivating teachers failed to work as expected.(2)The teachers’work stress still increased year by year.Therefore,this study concludes that the reform in Jia County failed to fulfill its goals and that the vigorous top-down reform did not lead to ideal results.A reason might be that the reform damaged the vested interests of teachers who represent the deep-rooted nepotism typically in the Chinese education community.Reforms of educational personnel system should give schools a full play regarding educational governance in the future.展开更多
文摘为研究在高速列车场景下车体横向振动对自由空间光(free space optical,FSO)通信指向误差的影响,首先利用TB/T 3352—2014《高速铁路无砟轨道不平顺谱》中的轨向、轨距不平顺功率谱推导出横向合成不平顺谱公式,用谱公式仿真生成横向合成不平顺数据;其次建立1/4车体3自由度横向车体振动模型,使用拉普拉斯变换推导出车体横向振动微分方程组的传递函数,搭建车体振动的Simulink仿真模型,推导车体横向位移的功率谱密度(power spectrum density,PSD),经统计得出仿真车体横向位移的概率密度函数(probability density function,PDF);最后利用车体横向位移PDF推导其导致的指向性误差的PDF。仿真验证了轨道横向合成不平顺谱公式、车体横向位移的PSD和PDF,以及横向位移导致的指向性误差的PDF。本研究获得的指向性误差的PDF可用于高铁FSO通信链路的信道建模和系统性能分析。
文摘Over recent years,the reform-driven development of education has been one primary idea of the Chinese government under the leadership of Xi Jinping.Above all,the reform of the personnel system,closely related to the interests of teachers,becomes the most sensitive link in the educational reform.To root out the restriction of education system on teachers and enhance their enthusiasm for work,Jia County carried out a reform of teacher personnel system from 2013 to 2016,including breaking the hierarchical restriction on teachers’administrative promotion,decentralizing the power of confirming the teachers’professional titles,eliminating the teachers with the worst performances,practicing performance salary,and other measures.In this study,we tracked 627 teachers regarding their work enthusiasm and stress during the three-year reform,analyzed the data through the Hierarchical Linear Model(HLM),and found that:(1)The teachers’enthusiasm for work increased over time,but did not significantly change with the consideration of the influence of the principals’leadership in teaching.The personnel system reform aiming at motivating teachers failed to work as expected.(2)The teachers’work stress still increased year by year.Therefore,this study concludes that the reform in Jia County failed to fulfill its goals and that the vigorous top-down reform did not lead to ideal results.A reason might be that the reform damaged the vested interests of teachers who represent the deep-rooted nepotism typically in the Chinese education community.Reforms of educational personnel system should give schools a full play regarding educational governance in the future.
