中国聚变工程实验堆涉氚阀门技术现状

阐述了中国聚变工程实验堆(CFETR)中涉氚阀门的技术要求及现状。CFETR涉氚阀门应选择寿命长、响应时间快的全金属阀门，在工作压力0.25MPa下整体漏率小于10^-9Pa·m³×s^-1。     

Extraordinary optical transmission through metal gratings with single and double grooved surfaces

We investigate the transmission properties of a normally incident TM plane wave through metal films with periodic parabolic-shaped grooves on single and double surfaces using the finite-difference-time-domain method. Nearly zero transmission efficiency is found at wavelengths corresponding to surface plasmon excitation on a flat surface in the case where the single surface is grooved. Meanwhile, resonant excitation of surface plasmon polariton (SPP) Bloch modes leads to a strong transmission peak at slightly larger wavelengths. When the grating is grooved on double surfaces, the transmission enhancement can be dramatically improved due to the resonant tunnelling between SPP Bloch modes.     

Splitting and focusing of light with metal nano-slits coated with nonlinear Kerr medium

<正>We demonstrate that a finite number of nano-slits can realize beam splitting and focusing of light by coating the metallic film surfaces with nonlinear Kerr medium.The numerical simulation shows that the beam splitting and focusing can be controlled by the incident light intensity.The splitting angle is quasiperiodically modulated by the incident light intensity,and the focusing length of forward propagating transmitted light decreases as the incident light intensity increases.These effects are explained by the surface plasmon polariton Bloch modes and self-focusing theory.     

Selective preparation of the maximum coherent superposition state in four-level atoms

We demonstrate that the maximum coherent superposition state can be selectively prepared using a sequence of pulse pairs in lambda-type atomic systems,with the final level as a doublet.In each pair,the Stocks pulse comes before the pump pulse,with their back edges overlapping.Numerical results indicate that by tuning the interval of the adjacent pulse pairs,the selective maximum coherent superposition state preparation between the initial and one of the final levels can be achieved.The phenomenon is caused by the accumulative property of the pulse sequence.     

等离子体装置中粉尘问题研究进展

等离子体装置中,带电粒子与壁材料相互作用会导致粉尘的产生。综述了主要等离子体装置中粉尘问题的实验研究现状,对主要装置中使用的诊断方法和所得到的实验结果进行了评述。提出了等离子体装置粉尘研究中存在的问题以及未来研究的方向。     

结合光流法与信息熵的人群突发事件检测与判断

在公园、学校、购物中心等人流密集的地方，如果发生火灾、地震或犯罪案件，易导致类似踩踏的安全事故。需要掌握区域内人群是混乱还是有序疏散的信息，从而尽快采取有效的应对措施，将人员伤亡降至最低。 提出了一种结合光流法与信息熵的人群突发事件检测与判断算法。通过LK光流算法从视频中提取运动物体的特征点，并得到特征点的位置信息；根据位置信息计算速度和加速度，分析运动强度，检测突发事件；由各速度矢量在方向上的分布得到概率，计算信息熵，由信息熵来判断视频中人群的状态是混乱还是有序。与同类算法相比，本算法能在准确检测突发事件的同时判断人群状态，适用于多种不同场景。