霍尔漂移对阳极层霍尔等离子体加速器电离效率的影响

以洛伦兹变换方法为基础,分析了阳极层霍尔等离子体加速器中电子的霍尔漂移,结果表明在交叉场中,霍尔漂移并不总是存在的,E/B的比值大于光速时,霍尔漂移将不存在.进一步的分析表明,霍尔漂移也并不总是回旋形式的,不同的电磁场配置以及不同的电子初始能量将带来不同形式的漂移,包括回旋形式,波浪线形式,甚至直线形式.电磁场的配置也决定着霍尔漂移的速度,在很大程度上影响着电子的能量,这就决定了放电时的电离效率.对不同电磁场配置进行数值模拟发现,合理的电磁场比值能够得到更好的电离效率(对于氩,这个数值大约为4×10⁶).不同的气体,根据其电离碰撞截面与电子能量的关系,都有不同的合理比值.     

Dynamical Convergence Trajectory in Networks

It is well known that topology and dynamics are two major aspects to determine the function of a network. We study one of the dynamic properties of a network： trajectory convergence, i.e. how a system converges to its steady state. Using numerical and analytical methods, we show that in a logical-like dynamical model, the occurrence of convergent trajectory in a network depends mainly on the type of the fixed point and the ratio between activation and inhibition links. We analytically proof that this property is induced by the competition between two types of state transition structures in phase space： tree-like transition structure and star-like transition structure. We show that the biological networks, such as the cell cycle network in budding yeast, prefers the tree-like transition structures and suggest that this type of convergence trajectories may be universal.     

Divisors on Generic Complete Intersections in Projective Space

Let be a generic complete intersection of hypersurfaces of degree in -dimensional projective space. We study the question when a divisor on is nonrational or of general type, and give an alternative proof of a result of Ein. We also give some improvement of Ein's result in the case .

     

模糊传感器训练算法

本文提出了模糊传感器的一种分段式训练调参方法。对温度模糊传感器的仿真结果表明，该方法能在不同的测量结构下，较好地解决人类感知温度的模糊语言描述问题。     

薄膜太阳电池的研究进展

介绍了薄膜太阳电池在光伏技术中的位置,详细叙述了非晶硅,铜铟锡,碲化镉等主要薄膜太阳电池的基本结构,制造方法,研究进展和现状,指出了存在的关键问题和解决的途径,并介绍了薄膜太阳电池的发展趋势和应用前景。     

有源消声耳罩中的通信信号补偿

在有源消声罩的很多应用场所,耳罩中引入了通信信号,在提高有源消声量的同时,还要保证通信信号的清晰。本文针对有源消声耳罩的不同消声结构,分析了其中通信信号所受到的影响,对于通信信号受影响较大的消声结构,提出了相应的补偿方案,推导了补偿器的理论补偿公式,并且实际设计了消声耳罩和相应的通信信号补偿器,实测了通信信号的补偿效果,就实验结果分析了通信信号补偿方案的有效性。     

实时单发测量的汤姆逊离子谱仪

介绍一种使用闪烁体耦合电子倍增电荷耦合器件（EMCCD）的方式对离子进行记录的汤姆逊能谱仪,可实现对离子能谱的实时单发测量。同时,该谱仪利用倾斜电极板对离子进行偏转,可减少由于离子打在电极板上产生的电磁噪声,能够提高实验结果的信噪比。该谱仪在北京大学4.5 MV静电加速器和26 MV串列加速器上进行了标定实验,测量了闪烁体将离子转化成光子后的探测效率,实验结果也验证了该谱仪的可行性和稳定性。该汤姆逊谱仪将用于北京大学激光加速器CLAPA对离子束流的测量研究。     

First Observation of 131Pm Decay

¹³¹Pm nucleus was produced in the ¹⁰⁶Cd (³²S,3p4n) ¹³¹Pm reaction. Theproducts were transported by helium jet and tape system, and X,γ single spectra and X-γ,γ-γ coincidence spectra were measured. The half-life of ¹³¹Pm has beendetermined to be (6.3±0.8)s. A partial decay scheme of ¹³¹Pm is proposed.