Dear Editor,A few studies have focused on exploring APOE gene- related effects on cognitive functions and brain activities in healthy populations. Bondi et aL found that ε4 carriers perform significantly worse on the...Dear Editor,A few studies have focused on exploring APOE gene- related effects on cognitive functions and brain activities in healthy populations. Bondi et aL found that ε4 carriers perform significantly worse on the California Verbal Learning Test than non-carriers in non-demented old subjects （mean age, 72 years）ε11. But the results are not entirely consistent. For example, Scarmeas et aL found no effect of the E4 allele on neuropsychological performance[2] in young adults, and Jochemsen et al. found that the ε4 allele is associated with age-related cognitive decline[3]. Furthermore, protective and negative effects of the E2 allele on cognition are inconsistent[4＇ s]. APOE E2 is thought to be a protective allele for AD in the elderly population due to its role in the superior cognitive performance of ε2 carriers compared to E3 or E4 carriers[5]. However, the ε2 allele has also been found to have a negative effect on AD pathology[4].展开更多
A reaction-diffusion model for a single species with age structure and nonlocal reaction for periodic time t is derived. Some results about the model with monotone birth function are firstly introduced, and then by co...A reaction-diffusion model for a single species with age structure and nonlocal reaction for periodic time t is derived. Some results about the model with monotone birth function are firstly introduced, and then by constructing two auxiliary equations and squeezing method, the spreading speed for the system with nonmonotone birth function is obtained.展开更多
A simple method is proposed to optimize the thickness parameter of the boundary layer of the saturation function in the Complementary Sliding Mode Control (CSMC). A pair of complementary sliding surfaces are construct...A simple method is proposed to optimize the thickness parameter of the boundary layer of the saturation function in the Complementary Sliding Mode Control (CSMC). A pair of complementary sliding surfaces are constructed. And the Taylor series is used to estimate the steady state error of CSMC system to optimize the parameter value for the boundary layer of the saturation function without artificial settings. This proposed CSMC strategy is applied to the speed regulation in permanent magnet synchronous motor with lump uncertainties. The experimental results show that the proposed CSMC strategy can obtain an optimal value for the boundary layer parameter effectively suppressing the chattering and keep an excellent system performance.展开更多
针对观测器估计精度偏低及高速列车系统的强耦合、受外界扰动、参数时变等问题,提出一种基于补偿函数观测器的分数阶非奇异快速终端滑模控制算法(Compensating Function Observer-Fractional Order Non-singular Fast Terminal Sliding ...针对观测器估计精度偏低及高速列车系统的强耦合、受外界扰动、参数时变等问题,提出一种基于补偿函数观测器的分数阶非奇异快速终端滑模控制算法(Compensating Function Observer-Fractional Order Non-singular Fast Terminal Sliding Mode Control,CFO-FONFTSMC),以提高高速列车速度控制的鲁棒性和控制精度.首先,建立高速列车纵向多质点动力学模型,设计高精度的补偿函数观测器对系统的总扰动进行实时估计并补偿;然后,设计一种带状态负指数控制律的分数阶非奇异快速终端滑模控制算法,用于对列车的运行曲线进行跟踪控制,并通过李雅普诺夫稳定性理论证明系统在有限时间内的收敛性;最后,以CRH3型高速列车参数和合肥站-蚌埠南站的实际线路为实例,分别跟踪理想运行曲线和节能优化运行曲线进行实验验证.仿真结果表明:所提算法跟踪理想运行速度曲线的平均误差为0.01377 km/h,跟踪带干扰的节能优化运行速度曲线的平均误差为0.0364 km/h,相较于基于扩张状态观测器的滑模和非奇异快速终端滑模控制方法,所提方法具有最小的跟踪误差和更高的跟踪精度,验证了其有效性和可行性,可为列车速度跟踪控制领域的研究提供参考.展开更多
基金supported by the National Natural Science Foundation of China (81130024)the National Key Technology R & D Program of the Ministry of Science and Technology of China during the 12th Five-Year Plan (2012BAI01B06)
文摘Dear Editor,A few studies have focused on exploring APOE gene- related effects on cognitive functions and brain activities in healthy populations. Bondi et aL found that ε4 carriers perform significantly worse on the California Verbal Learning Test than non-carriers in non-demented old subjects （mean age, 72 years）ε11. But the results are not entirely consistent. For example, Scarmeas et aL found no effect of the E4 allele on neuropsychological performance[2] in young adults, and Jochemsen et al. found that the ε4 allele is associated with age-related cognitive decline[3]. Furthermore, protective and negative effects of the E2 allele on cognition are inconsistent[4＇ s]. APOE E2 is thought to be a protective allele for AD in the elderly population due to its role in the superior cognitive performance of ε2 carriers compared to E3 or E4 carriers[5]. However, the ε2 allele has also been found to have a negative effect on AD pathology[4].
基金Supported by the NSF of China(11171120)Supported by the Doctoral Program of Higher Education of China(20094407110001)Supported by the NSF of Guangdong Province(10151063101000003)
文摘A reaction-diffusion model for a single species with age structure and nonlocal reaction for periodic time t is derived. Some results about the model with monotone birth function are firstly introduced, and then by constructing two auxiliary equations and squeezing method, the spreading speed for the system with nonmonotone birth function is obtained.
基金Sponsored by the National Natural Science Foundation of China(Grant No.61174051)the Natural Science Foundation of Fujian Province(Grant No.2017J05101)the Technology Project of Fujian Province(Grant No.2019H0007)
文摘A simple method is proposed to optimize the thickness parameter of the boundary layer of the saturation function in the Complementary Sliding Mode Control (CSMC). A pair of complementary sliding surfaces are constructed. And the Taylor series is used to estimate the steady state error of CSMC system to optimize the parameter value for the boundary layer of the saturation function without artificial settings. This proposed CSMC strategy is applied to the speed regulation in permanent magnet synchronous motor with lump uncertainties. The experimental results show that the proposed CSMC strategy can obtain an optimal value for the boundary layer parameter effectively suppressing the chattering and keep an excellent system performance.
文摘针对观测器估计精度偏低及高速列车系统的强耦合、受外界扰动、参数时变等问题,提出一种基于补偿函数观测器的分数阶非奇异快速终端滑模控制算法(Compensating Function Observer-Fractional Order Non-singular Fast Terminal Sliding Mode Control,CFO-FONFTSMC),以提高高速列车速度控制的鲁棒性和控制精度.首先,建立高速列车纵向多质点动力学模型,设计高精度的补偿函数观测器对系统的总扰动进行实时估计并补偿;然后,设计一种带状态负指数控制律的分数阶非奇异快速终端滑模控制算法,用于对列车的运行曲线进行跟踪控制,并通过李雅普诺夫稳定性理论证明系统在有限时间内的收敛性;最后,以CRH3型高速列车参数和合肥站-蚌埠南站的实际线路为实例,分别跟踪理想运行曲线和节能优化运行曲线进行实验验证.仿真结果表明:所提算法跟踪理想运行速度曲线的平均误差为0.01377 km/h,跟踪带干扰的节能优化运行速度曲线的平均误差为0.0364 km/h,相较于基于扩张状态观测器的滑模和非奇异快速终端滑模控制方法,所提方法具有最小的跟踪误差和更高的跟踪精度,验证了其有效性和可行性,可为列车速度跟踪控制领域的研究提供参考.
