中子活化Cu样品“跑兔”装置

 针对惯性约束聚变（ICF）实验装置上中子活化Cu样品的传递问题,设计并研制了“跑兔”装置,解决了“兔子”的顺畅传输、减速、定位、缓冲等问题。实验验证结果表明,“兔子”运动特性的实验曲线与理论模拟曲线吻合得很好,“兔子”可在1.12 s的时间范围内顺利地传输到14.3 m远的指定位置,平均速度为12.8 m/s,完全满足Cu样品的活化分析要求。     

"Metric" complexity for weakly chaotic systems

We consider the number of Bowen sets necessary to cover a large measure subset of the phase space. This introduces some complexity indicator characterizing different kinds of (weakly) chaotic dynamics. Since in many systems its value is given by a sort of local entropy, this indicator is quite simple to calculate. We give some examples of calculations in nontrivial systems (e.g., interval exchanges and piecewise isometries) and a formula similar to that of Ruelle-Pesin, relating the complexity indicator to some initial condition sensitivity indicators playing the role of positive Lyapunov exponents.