用于双色全息存储(Fe,Cu)∶LiNbO3晶体的参量优化计算

在确定Cu在LiNbO3晶体中对应于365 nm和633 nm的激发系数、复合系数、光伏系数的基础上,采用龙格库塔(Runge-Kutta)数值方法理论研究了双掺杂(Fe,Cu)∶LiNbO3晶体的深浅能级的掺杂组分比、氧化还原状态对双色全息存储的记录灵敏度和动态范围的影响,并探讨了同时取得尽可能大的灵敏度和动态范围的晶体条件。结果表明,为了同时得到较大的记录灵敏度和动态范围,在实际应用中选用浅能级掺杂浓度为5.0×1025m-3,深能级掺杂浓度为3×1024~3×1025m-3之间的弱氧化晶体是合适的。     

Giant magnetoresistance effect in nanostructures consisting of magnetic–electric barriers

The GMR effect in magnetic–electric barrier nanostructure, which can be realized experimentally by depositing two parallel metallic ferromagnetic strips with an applied voltage on the top of heterostructure, is investigated theoretically. It is shown that a considerable GMR effect can be achieved in such nanosystems due to the significant transmission difference for electrons tunneling through parallel and antiparallel magnetization configurations. It is also shown that the magnetoresistance ratio is strongly dependent upon the applied voltage to metallic ferromagnetic strips in nanosystems, thus may leading to voltage-tunable GMR devices.     

电气原理草图语义理解系统开发

在当前已有的手绘草图识别系统及算法的基础上,设计了一个简单的手绘电气元件识别系统.通过在线采集获取手绘图每个笔画的始终点坐标以及每个笔画上所有的采样点的坐标,然后通过平滑处理以及去重处理来降低因输入时候的抖动噪音之类的因素对识别的影响.实现了基于图元以及图元数量的单个电气元件的识别方法.系统使用MATLAB做为软件开发平台,通过仿真验证算法的可行性,所达到的识别效果能够实现预期的设计要求.     

Electrochemical polymerization of alizarin and the electrochemical properties of poly(alizarin)

Electrochemical polymerization of alizarin on glassy carbon electrode (GCE) was carried out in acidic solution by cyclic voltammetry (CV), and the polymerization process was monitored by electrochemical quartz crystal microbalance (EQCM). A possible mechanism concerning the polymerization of alizarin was also proposed in this work. The as-synthesized poly(alizarin) was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The study on electrode reaction process shows that the electrode reaction of poly(alizarin) is controlled by diffusion. Finally, the activation energy (E _a) of the electrode reactions of poly(alizarin) was obtained according to the temperature dependence of the redox peak currents.     

The photocatalytic mechanism of BiOI with oxygen vacancy and iodine self-doping

The photocatalytic mechanism of BiOI with an oxygen vacancy and iodine self-doping is investigated by studying their structural, electronic and optical properties. The results of the first-principle calculations indicate that the utilization of the visible light region is broadened, and thus the photocatalytic performance is improved, via introducing an oxygen vacancy or I dopant. Among them, I-Bi doped BiOI shows the best photocatalytic performance, and it is also the preferred one of the three structures due to its better stability. The occurrence of I-Bi or I-I interactions in the original double iodine layer along with the introduction of I dopant leads to a planar localization of the photocatalytic mechanism. Then it is expected that the photo-generated carriers will transfer to the catalyst surface more easily; the photocatalytic activity of BiOI relies on the planar localization to a great degree.     

PPLT倍频宽线宽掺镱双包层光纤放大激光

分别通过理论和实验研究了周期性极化的钽酸锂（PPLT）倍频宽线宽准连续掺镱双包层光纤放大激光.PPLT样品长为40 mm,极化周期为7.67 μm.基频光的中心波长为1064 nm,线宽约为6 nm.从基频光的光谱特性出发,利用超晶格倍频理论,解释了实验中获得的倍频温度与二次谐波功率之间的关系.在基频光的功率为2.2 W时,获得的宽线宽光纤激光倍频效率为1.8%.     

Tomographic analysis of the central magnetohydrodynamic oscillations on the HT-7 tokamak

Multi-channel soft x-ray (SX) detectors are applied to generate images of magnetohydrodynamic (MHD) oscillation on the HT-7 tokamak, and the data from SX cameras are analysed by using the Fourier--Bessel harmonic reconstruction method and the singular value decomposition. The image reconstruction of SX emissivity is obtained on the assumption of plasma rigid rotation. One of the important phenomena in the HT-7 discharge is the transition from the sawtooth oscillations to the MHD oscillations when the plasma density grows higher. The MHD structure observed in the SX tomography is featured as follows: the magnetic surface of MHD structure is made up of the crescent-shaped ``hot core' and the circular ``cold bubble'. The structure of the magnetic surface is relatively stable. It rotates in the direction of the electron diamagnetic drift at a frequency being the oscillation frequency of the MHD oscillations.