Uncertainty propagation, one of the structural engineering problems, is receiving increasing attention owing to the fact that most significant loads are random in nature and structural parameters are typically subject...Uncertainty propagation, one of the structural engineering problems, is receiving increasing attention owing to the fact that most significant loads are random in nature and structural parameters are typically subject to variation. In the study, the collocation interval analysis method based on the first class Chebyshev polynomial approximation is presented to investigate the least favorable responses and the most favorable responses of interval-parameter structures under random excitations. Compared with the interval analysis method based on the first order Taylor expansion, in which only information including the function value and derivative at midpoint is used, the collocation interval analysis method is a non-gradient algorithm using several collocation points which improve the precision of results owing to better approximation of a response function. The pseudo excitation method is introduced to the solving procedure to transform the random problem into a deterministic problem. To validate the procedure, we present numerical results concerning a building under seismic ground motion and aerofoil under continuous atmosphere turbulence to show the effectiveness of the collocation interval analysis method.展开更多
The membrane bioreactor(MBR)technology is a rising star for wastewater treatment.The pollutant elimination and membrane fouling performances of MBRs are essentially related to the dissolved organic matter(DOM)in the s...The membrane bioreactor(MBR)technology is a rising star for wastewater treatment.The pollutant elimination and membrane fouling performances of MBRs are essentially related to the dissolved organic matter(DOM)in the system.Three-dimensional excitation-emission matrix(3D-EEM)fluorescence spectroscopy,a powerful tool for the rapid and sensitive characterization of DOM,has been extensively applied in MBR studies;however,only a limited portion of the EEM fingerprinting information was utilized.This paper revisits the principles and methods of fluorescence EEM,and reviews the recent progress in applying EEM to characterize DOM in MBR studies.We systematically introduced the information extracted from EEM by considering the fluorescence peak location/intensity,wavelength regional distribution,and spectral deconvolution(giving fluorescent component loadings/scores),and discussed how to use the information to interpret the chemical compositions,physiochemical properties,biological activities,membrane retention/fouling behaviors,and migration/transformation fates of DOM in MBR systems.In addition to conventional EEM indicators,novel fluorescent parameters are summarized for potential use,including quantum yield,Stokes shift,excited energy state,and fluorescence lifetime.The current limitations of EEM-based DOM characterization are also discussed,with possible measures proposed to improve applications in MBR monitoring.展开更多
针对切向聚磁型并联结构混合励磁电机(TMPS-HESM)随着励磁电流增加导致齿槽转矩剧增容易引发电机振动噪声的问题,根据齿槽转矩的产生原理,探讨改变转子极靴宽度、磁极偏心距和气隙长度削弱电机齿槽转矩的可行性。借助Maxwell and Workbe...针对切向聚磁型并联结构混合励磁电机(TMPS-HESM)随着励磁电流增加导致齿槽转矩剧增容易引发电机振动噪声的问题,根据齿槽转矩的产生原理,探讨改变转子极靴宽度、磁极偏心距和气隙长度削弱电机齿槽转矩的可行性。借助Maxwell and Workbench and Optislong联合仿真软件建立8极48槽TMPS-HESM模型,运用遗传算法进行全局多目标优化,得到pareto最优解集后使用优劣解距离法(TOPSIS)客观选取最优解。最后对比分析优化前后电机的各项其他性能,结果表明:采用遗传算法和TOPSIS法对电机参数进行优化,能提升电机多目标优化效率,不仅可解决混合励磁电机励磁电流增加导致齿槽转矩剧增的问题,还能有效削弱电机转矩脉动,提升电机平均转矩,在减少电机的振动噪声和提高电机输出转矩方面均取得改善。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10872017, 90816024 and 10876100)111 Project (Grant No. B07009)
文摘Uncertainty propagation, one of the structural engineering problems, is receiving increasing attention owing to the fact that most significant loads are random in nature and structural parameters are typically subject to variation. In the study, the collocation interval analysis method based on the first class Chebyshev polynomial approximation is presented to investigate the least favorable responses and the most favorable responses of interval-parameter structures under random excitations. Compared with the interval analysis method based on the first order Taylor expansion, in which only information including the function value and derivative at midpoint is used, the collocation interval analysis method is a non-gradient algorithm using several collocation points which improve the precision of results owing to better approximation of a response function. The pseudo excitation method is introduced to the solving procedure to transform the random problem into a deterministic problem. To validate the procedure, we present numerical results concerning a building under seismic ground motion and aerofoil under continuous atmosphere turbulence to show the effectiveness of the collocation interval analysis method.
基金the National Natural Science Foundation of China(No.51778599)the Beijing Natural Science Foundation(No.LI82044)+1 种基金the CAS Strategic Priority Research Programmer(A)(No.XDA20050103)the Youth Innovation Promotion Association CAS(No.110500EA62)。
文摘The membrane bioreactor(MBR)technology is a rising star for wastewater treatment.The pollutant elimination and membrane fouling performances of MBRs are essentially related to the dissolved organic matter(DOM)in the system.Three-dimensional excitation-emission matrix(3D-EEM)fluorescence spectroscopy,a powerful tool for the rapid and sensitive characterization of DOM,has been extensively applied in MBR studies;however,only a limited portion of the EEM fingerprinting information was utilized.This paper revisits the principles and methods of fluorescence EEM,and reviews the recent progress in applying EEM to characterize DOM in MBR studies.We systematically introduced the information extracted from EEM by considering the fluorescence peak location/intensity,wavelength regional distribution,and spectral deconvolution(giving fluorescent component loadings/scores),and discussed how to use the information to interpret the chemical compositions,physiochemical properties,biological activities,membrane retention/fouling behaviors,and migration/transformation fates of DOM in MBR systems.In addition to conventional EEM indicators,novel fluorescent parameters are summarized for potential use,including quantum yield,Stokes shift,excited energy state,and fluorescence lifetime.The current limitations of EEM-based DOM characterization are also discussed,with possible measures proposed to improve applications in MBR monitoring.
文摘针对切向聚磁型并联结构混合励磁电机(TMPS-HESM)随着励磁电流增加导致齿槽转矩剧增容易引发电机振动噪声的问题,根据齿槽转矩的产生原理,探讨改变转子极靴宽度、磁极偏心距和气隙长度削弱电机齿槽转矩的可行性。借助Maxwell and Workbench and Optislong联合仿真软件建立8极48槽TMPS-HESM模型,运用遗传算法进行全局多目标优化,得到pareto最优解集后使用优劣解距离法(TOPSIS)客观选取最优解。最后对比分析优化前后电机的各项其他性能,结果表明:采用遗传算法和TOPSIS法对电机参数进行优化,能提升电机多目标优化效率,不仅可解决混合励磁电机励磁电流增加导致齿槽转矩剧增的问题,还能有效削弱电机转矩脉动,提升电机平均转矩,在减少电机的振动噪声和提高电机输出转矩方面均取得改善。
