Adaptive prescribed performance control for nonlinear pure-feedback systems: a scalarly virtual parameter adaptation approach

Nonlinear Dynamics - In this paper, an adaptive prescribed performance controller, consisting of a novel scalarly virtual parameter adaptation (SVPA) technique, is developed for a class of...     

超声相控阵控制、采集与全并行处理系统设计

针对超声相控阵检测系统工作环境较为恶劣、延时发射电路复杂、多路信号的采集难以单板实现以及多路信号处理实时性差等问题,提出了一种基于CPCI总线和FPGA的超声相控阵控制、采集与全并行处理系统的设计。本设计采用CPCI总线架构,可以在高尘、高冲击负荷等恶劣环境下工作,采用带高速串行LVDS接口的ADS445与XC5VSX95T相组合的方式来实现单板16路信号的高速信号采集和全并行处理,采用XC5VSX95T中的高速计数器来实现2ns的高精度延时发射,还提供了功能强大的主控软件便于用户操作。分析结果表明,多路AD+FPGA的硬件结构特别适合相控阵系统。实测结果表明,本系统可以较好地对钢管的缺陷进行实时检测和A扫与B扫成像。     

A velocity-adaptive Couzin model and its performance

Typical collective behaviors in the Couzin model are exhibited by simulation, and some performances of the system such as convergence probability and relative size are analyzed. To provide an alternative to the constant-speed setting of the Couzin model, a velocity-adaptive strategy is presented. Simulation shows that in the new model both the convergence probability and the relative size are prominently enhanced.     

9MeV,小于0.1mm微焦点X射线源验证实验

密度高、成像分辨率高、成像速度快的X射线数字成像检测需要高能微焦点大剂量X射线源,高品质电子源是实现这一X射线源的关键手段。基于中国工程物理研究院太赫兹自由电子激光的主加速器,验证了低发射度、低能散度的高亮度电子束实现高能微焦点的可行性,得到电子束半高全宽尺寸小于70μm的9 MeV微焦点,并初步开展成像实验,双丝像质计焦斑清晰分辨9D号丝,丝直径0.13 mm。     

Neural adaptive dynamic surface control for uncertain strict-feedback nonlinear systems with nonlinear output and virtual feedback errors

Nonlinear Dynamics - This paper addresses a new nonlinear gain feedback-based neural adaptive dynamic surface control (DSC) method for a sort of strict-feedback nonlinear systems in the presence of...     

Enhanced homing of mesenchymal stem cells to the ischemic myocardium by ultrasound-targeted microbubble destruction

In recent years, ultrasound-targeted microbubble destruction (UTMD) has been utilised for the targeted delivery of stem cells. We tested the effects of the myocardial micro-environment changes induced by UTMD on promoting the homing of mesenchymal stem cells (MSCs) to the ischemic myocardium. Dogs were randomly divided into two groups and treated with or without UTMD after the establishment of myocardial infarction models. 4,6-diamino-2-phenyl indole (DAPI) labelled MSCs were transplanted via coronary injections 2 weeks after myocardial infarction in both groups. The results from real-time PCR and western blot analyses indicated that the expression of various cytokines in UTMD-treated dogs was much higher than that observed in non-treated dogs. Histopathological findings demonstrate that ultrasound at a frequency of 1 MHz and an intensity of 1.0 W/cm² provoked inflammatory reactions with mild myocardial damage. Myocardial microenvironment changes caused by UTMD may promote the homing of MSCs to the ischemic myocardium. This non-invasive technique may be a promising method for cardiac cell transplantation therapy.     

Neural adaptive control of uncertain chaotic systems with input and output saturation

Nonlinear Dynamics - This paper is concerned with the neural adaptive control design problem of a class of chaotic systems with uncertain dynamics, input and output saturation. To attenuate the...