三色圆偏振激光组合脉冲驱动氦原子产生椭圆偏振的阿秒脉冲

我们提出利用频率为ω,3ω和强度较弱的2ω组成的三色圆偏振激光组合脉冲驱动氦原子能够得到椭偏率较大的阿秒脉冲链的一种方法.通过强场近似方法,计算了氦原子在两色和三色圆偏振激光组合脉冲驱动下发射高次谐波谱及其合成阿秒脉冲链,比较了氦原子(初态为s态)在这两种情况下发射高次谐波谱的特点及其合成阿秒脉冲链椭偏率的大小,结果发现,在反旋的两色ω,3ω激光脉冲基础上加入了频率为2ω的第三色激光脉冲联合作用到氦原子上,所得到的阿秒脉冲链的椭偏率相对于双圆场情况下有所增加,通过调整ω,3ω激光的强度比,并且选择适当的第三色激光的强度,对初态为s态的原子,仍能够得到具有较大椭偏率的阿秒脉冲链.     

非均匀性和彩色失真图像的同时补偿

针对CCD摄像机或扫描仪产生图像存在颜色偏差和非均匀性使图像质量下降 ,通过多元线性回归分析方法同时对图像的非均匀性和彩色失真进行补偿 ,使输出图像信号均匀且其色度值与输入信号的色度值相匹配。依据算法进行了仿真试验 ,结果表明补偿后图像与原图像相比大体相近 ,且比非均匀性校正和彩色校正分步进行方法计算量小 ,节省时间     

基于ANSYS的高温超导混合磁轴承悬浮力分析

基于商用电磁场有限元软件ANSYS以及Bean临界态模型,对由圆柱形高温超导块材、永磁体和超导线圈组成的新型高温超导混合磁轴承的电磁场分布及悬浮力进行了仿真分析,研究了超导线圈对高温超导混合磁轴承悬浮力的影响,同时还通过实验测试了悬浮力。结果表明:仿真与实验具有较好的一致性,使用软件仿真方便可行,其结果较为准确可靠,可为高温超导混合磁轴承的设计和优化提供理论依据。     

ICP-AES测定邻苯二甲酸氢钾-氢氧化钠作用下土壤中重金属全量及形态分析

空白土壤作为质量控制样品,采用邻苯二甲酸氢钾-氢氧化钠进行处理土壤样品为对照,用HNO₃-HF-HClO₄混酸对土壤样品进行消化,运用等离子体发射光谱仪(ICP-AES)测定了提取处理后土壤样品中Mo, Pb, As, Hg, Cr, Cd, Zn, Cu, Ni的全量以及酸可提取态、氧化物结合态、有机结合态三种化学形态的含量。获知不同pH的邻苯二甲酸氢钾-氢氧化钠缓冲溶液对土壤中重金属全量及形态转化作用的影响。结果表明：除Pb和Zn外,投加不同pH邻苯二甲酸氢钾-氢氧化钠缓冲溶液对土壤中重金属全量的消解和测定有促进作用。邻苯二甲酸氢钾-氢氧化钠缓冲溶液对土壤中Cr, Cu, Hg, Pb的酸可提取态、对土壤中As, Hg, Pb, Zn的氧化结合态、对土壤中As和Hg的有机结合态的转化有促进作用。在pH 5.8时,Cu和Hg的酸可提取态的含量最大值分别为2.180和0.632 mg·kg-1;在pH 6.2时,Pb的氧化结合态的含量最大值为27.792 mg·kg-1;在pH 6.0时,Hg的有机结合态含量最大值为4.715 mg·kg-1。     

Cluster synchronization in a network of non-identical dynamic systems

Cluster synchronization in a network of non-identical dynamic systems is studied in this paper, using two-cluster synchronization for detailed analysis and discussion. The results show that the common intercluster coupling condition is not always needed for the diffusively coupled network. Several sufficient conditions are obtained by using the Schur unitary triangularization theorem, which extends previous results. Some numerical examples are presented for illustration.     

Removal of oxygen from silicon by electron beam melting

Small amounts of multicrystalline silicon were melted in an electron beam furnace in different experimental conditions in order to investigate the oxygen evaporation behavior during the electron beam melting (EBM) process. The oxygen content level before and after EBM was determined by secondary ion mass spectroscopy. The oxygen content was reduced from 6.177 to 1.629 ppmw when silicon was melted completely at 15 kW with removal efficiency up to 73.6 %. After that, it decreased continually to <0.0517 ppmw when the refining time exceeded 600 s with a removal efficiency of more than 99.08 %. During the melting process, the evaporation rate of silicon is 1.10 × 10^?5 kg/s. The loss of silicon could be reduced up to 1.7 % during oxygen removal process to a desirable figure, indicating EBM is an effective method to remove oxygen from silicon and decrease the loss of silicon.     

Superballistic wavepacket spreading in double kicked rotors

We investigate possible ways in which a quantum wavepacket spreads. We show that in a general class of double kicked rotor system, a wavepacket may undergo superballistic spreading; i.e., its variance increases as the cubic of time. The conditions for the observed superballistic spreading and two related characteristic time scales are studied. Our results suggest that the symmetry of the studied model and whether it is a Kolmogorov-Arnold-Moser system are crucial to its wavepacket spreading behavior. Our study also sheds new light on the exponential wavepacket spreading phenomenon previously observed in the double kicked rotor system.