Dielectric susceptibility of a ferroelectric bilayer film with surface transition layers

Using the transverse Ising model within the framework of the mean-field theory, we investigate a ferroelectric bilayer film with the surface transition layer within each constituent slab and an antiferroelectric interfacial coupling between two slabs. The combined influence of the surface transition layer and antiferroelectric interfacial coupling on the dielectric susceptibility of a bilayer film is discussed in detail. The results show that the surface transition layer plays a crucial role in dielectric susceptibility of a bilayer film.     

一类四元数矩阵三次方程的可解性(英文)

确立了某类分块矩阵[M（₁1） M₁₂ XM₂₁ Y M₂₃Z M₃₂ M₃₃]的最大秩公式,其中,X,Y和Z是三个受限于四元数线性矩阵方程A₁X=C₁,XB₁=C₂,A₂Y=D₁,YB₂=D₂,A₃Z=E₁,ZB₃=E₂的变量矩阵.作为该公式的一项应用,我们推导出上述矩阵方程解集等同于某类四元数三次矩阵方程组A₁X=C₁,XB₁=C₂,A₂Y=D₁,YB₂=D₂,A₃Z=E₁,ZB₃=E₂,XYZ=J解集的条件.     

用于EMBCCD图像信号采集的SDRAM控制器设计

SDRAM作为高速大容量存储器应用于视频采集系统十分方便。首先简介了SDRAM存储器的控制原理,然后介绍了EMBCCD(电子倍增背照明CCD)成像系统中图像数据的缓存和VGA显示。利用FPGA成功地实现了SDRAM控制器的设计。该控制器能够控制两片SDRAM乒乓操作,实现了EMBCCD图像信号的缓存。所获得的视频图像稳定、清晰、流畅。     

碳源对锂离子电池正极材料Li3V2（PO4）3性能的影响

分别以柠檬酸、葡萄糖和蔗糖为碳源,采用球磨与碳热还原结合法制备了锂离子电池正极材料Li3V2(PO4)3/C。采用TG-DTA分析确定了合成过程的反应机理。通过XRD、SEM及恒电流充放电等测试研究了碳源对产物物理及电化学特性的影响。结果表明,碳源的选择对产物形貌和电化学性能影响较大。不同碳源制备的材料都具有单一相的Li3V2(PO4)3晶体结构,以柠檬酸为碳源制备的磷酸钒锂综合电化学性能较好,0.1 C和1 C条件下,首次放电容量分别为151.0 mAh·g-1和131.6 mAh.g-1,50次循环后容量保持率为95.0%和96.6%。     

Composite stokes singularities in coherently and incoherently superimposed vector optical fields

The composite Stokes singularities formed in the coherent and incoherent superposition of two vector monochromatic coherent optical fields are studied and compared analytically and numerically. It is shown that the dynamic behavior of composite Stokes singularities depends on the superposition scheme (coherent or incoherent superposition), initial spatial distributions of the two superimposed fields, and propagation distance, and for the coherent superposition additionally depends on the relative phase of the two fields. There exist S₁₂ (C-points), S₃₁, S₂₃ composite singularities, and L-lines, in particular, V-points and C-lines at the transverse plane. Generally, both V-points and C-lines are unstable. For the coherent superposition the degree of polarization P=1, whereas for the incoherent superposition P may be less than 1 and is variable upon propagation. The results are illustrated analytically and numerically.     

On the use of NR-PC flat lens for square target detection and imaging by lens-combined scanning scheme

In the paper, target detection and imaging from refraction photonic crystal (NR-PC) slab lens is studied by the finite-difference time-domain (FDTD) method. Numerical simulation shows that, there is a transmission peak with a value far greater than unit, resulting from the mini-forbidden bands and resonance excitation at the resonance frequency of 0.3068 (a/λ). When a target is placed at the focus point (F₂) of the NR-PC lens, its image and great amplitude could be formed in the vicinity of the point source through the focusing of backscattered optical wave from the target. Further investigation demonstrates that the lens-combined scanning scheme provides higher refocusing resolution than lens-fixed and non-dynamic scanning scheme for square target detection and imaging.     

D301树脂、330树脂对双酚A吸附性能的对比

用静态吸附法对比研究D30l树脂、330树脂对环境激素双酚A的吸附性能。实验结果表明:相同条件下,D301树脂对双酚A的吸附量大干330树脂对双酚A的吸附量;330树脂在pH=4—9时对双酚A的吸附量最大,在pH值为11.31时,D301树脂对双酚A的吸附量最大,其吸附量大于330树脂对双酚A的最大吸附量;随着盐含量的升高,330树脂对双酚A的吸附量先迅速降低后平缓升高,而D301树脂对双酚A的吸附量随盐含量的升高逐渐增大;在80%C₂H₅OH和2mol/L NaOH的混合解吸剂中,D301、330树脂上双酚A的解吸率分别为99.99%、97.78%。D301树脂对双酚A的吸附存在离子交换,但以π—π作用为主,330树脂对双酚A的吸附以离子交换为主。     

High efficiency and good beam quality of electro-optic, cavity-dumped and double-end pumped Nd:YLF laser

In this paper, we describe a Nd:YLF laser based on high-speed RTP electro-optical cavity dumping technique. Two home-made 150 W fiber pump modules are used from both sides to pump Nd:YLF crystal. Coupling systems are the key elements in end-pumped solid-state lasers, the aberrations of which greatly affect the efficiency of the lasers. In order to get high efficient and good quality laser output, the optical software ZEMAX is used to design a four-piece coupling system. When the pumped energy is 32 mJ at the repetition rate of 1 Hz, the output energy is 6.5 mJ with 2.5 ns pulse width. When the pumped energy is 13.1 W at the repetition rate of 200 Hz, the output energy is 2.2 W with small M ² factor where M _x ² is 1.04, and M _y ² is 1.05, and the light-light conversion efficiency is up to 16.8%.     

Applications of VUV extra‐focus mechanism: high‐performance dual‐mode monochromator from VUV to soft X‐ray

A new monochromator scheme is presented in which an extra‐focus constant‐included‐angle varied‐line‐spacing cylindrical‐grating monochromator (extra‐focus CIA‐VCGM) is conveniently combined with a variable‐included‐angle varied‐line‐spacing plane‐grating monochromator (VIA‐VPGM). This dual‐mode solution delivers high performance in the energy range from vacuum ultraviolet (VUV) to soft X‐ray. The resolving power and the efficiency of this dual‐mode grating monochromator are analyzed in detail based on realistic parameters. Comparisons with the commonly used variable‐included‐angle plane‐grating monochromator and normal‐incidence monochromator (VIA‐PGM/NIM) hybrid monochromator are made.     

有机光敏二极管的功能材料探索及其器件结构

有机光敏二极管具有功能材料种类丰富、光敏波长可调控、成本低和可在柔性基底上制备等优点,在图像传感、免疫探测、光学通信等方面有着重要的应用前景.本文对近年来引起广泛关注的一些有机光敏二极管材料进行了归纳,探讨了它们在对不同波长敏感的光敏器件中的特性,总结了有机光敏二极管的结构优化、界面修饰和界面传输机理及其内部光强分布的相关研究,并介绍了一些基于有机光敏二极管的光电功能器件实际应用.最后,对有机光敏二极管未来的发展方向和应用前景进行了展望.