Investigation on latch-up susceptibility induced by high-power microwave in complementary metal–oxide–semiconductor inverter

The latch-up effect induced by high-power microwave(HPM) in complementary metal–oxide–semiconductor(CMOS) inverter is investigated in simulation and theory in this paper. The physical mechanisms of excess carrier injection and HPM-induced latch-up are proposed. Analysis on upset characteristic under pulsed wave reveals increasing susceptibility under shorter-width pulsed wave which satisfies experimental data, and the dependence of upset threshold on pulse repetitive frequency(PRF) is believed to be due to the accumulation of excess carriers. Moreover, the trend that HPMinduced latch-up is more likely to happen in shallow-well device is proposed.Finally, the process of self-recovery which is ever-reported in experiment with its correlation with supply voltage and power level is elaborated, and the conclusions are consistent with reported experimental results.     

机械轴承控制系统中的摩擦补偿

摩擦是机械轴承控制系统中最主要的扰动因素,也是影响系统低速跟踪性能的最主要因素。针对系统中动态摩擦力矩的影响,为了进一步提高系统的位置跟踪性能,提出一种重复自适应控制方法。该方法的控制律包含一个参数自适应律、等效PD控制律和一个重复控制律,其中,参数自适应律用来估计未知模型参数并予以补偿,而插入的重复控制器用来提高系统运行曲线的跟踪性能。系统中摩擦模型采用摩擦参数非一致性变化的LuGre动态模型。Lyapunov方法证明该补偿方法保证了闭环系统全局稳定性和对期望位置信号的渐近跟踪。最后,通过对控制系统的仿真研究验证了所提出方法的有效性。     

低抖动快前沿高电压重复率触发器

 介绍了一种低抖动、快前沿高电压重复率触发器,输出参数为：重复率可达100 pulse/s,输出时延约225 ns,抖动约1 ns,前沿约26 ns,脉宽约70 ns,高阻负载上电脉冲的峰值可达-40 kV,重复率为50 pulse/s时,峰值可达-51 kV,单次工作时的峰值可达-60 kV。该触发器主要由控制单元、高压供电单元与脉冲形成单元构成,脉冲形成单元采用了低电感电容对负载快放电的结构,建立开关为氢闸流管。实验发现,氢闸流管存在微导通状态,开关的通道电阻及维持的时间与开关极间的电势差有关;电势差越高,通道电阻越小,微导通状态维持的时间越长。此外,氢闸流管的导通性能受灯丝加热电源的影响明显,当加热电压较低时,氢闸流管导通缓慢,延时与抖动较大,当加热电压过高时,氢闸流管易于发生自击穿。     

Multivariate analysis of diffusion tensor imaging data improves the detection of microstructural damage in young professional boxers

In this study, we present two different methods of multivariate analysis of voxel-based diffusion tensor imaging (DTI) data, using as an example data derived from 59 professional boxers and 12 age-matched controls. Conventional univariate analysis ignores much of the diffusion information contained in the tensor. Our first multivariate method uses the Hotelling's T² statistic and the second uses linear discriminant analysis to generate the linear discriminant function at each voxel to form a separability metric. Both multivariate methods confirm the findings from the individual metrics of large-scale changes in the bilateral inferior temporal gyri of the boxers, but they also reveal greater sensitivity as well as identifying major subcortical changes that had not been evident in the univariate analyses. Linear discriminant analysis has the added strength of providing a quantitative measure of the relative contribution of each metric to any differences between the two subject groups. This novel adaptation of statistical and mathematical techniques to neuroimaging analysis is important for two reasons. Clinically, it develops the findings of a previous mild head injury study, and, methodologically, it could equally well be applied to multivariate studies of other pathologies.