Effects of South China Sea/western North Pacific summer monsoon on tropospheric biennial oscillation （TBO）

Several theories have been developed to explain tropical biennial oscillation (TBO), as an air--sea interactive system to impact Asian and global weather and climate, and some models have been established to produce a TBO. A simple 5-box model, with almost all the key processes associated with TBO, can produce a TBO by including air--sea interactions in the monsoon regions. Despite that, the South China Sea/western North Pacific summer monsoon (SCS/WNPSM), a very important monsoon subsystem, is neglected. In this paper, based on the dynamical framework of 5-box model, the term of SCS/WNPSM has been added and a 6-box model has been developed. Comparing the difference of TBO sensibilities with several key parameters, air--sea coupling coefficient α, SST-thermocline feedback coefficient γ and wind-evaporation feedback coefficient λ, between the modified model and original model, TBO is more sensible to the parameters in the new model. The results imply that the eastern Pacific and local wind-evaporation play more important roles in the TBO when including SCS/WNPSM.     

An asymptotic solving method for the periodic solution of a class of disturbed nonlinear evolution equation

<正>A class of disturbed evolution equation is considered using a simple and valid technique.We first introduce the periodic traveling-wave solution of a corresponding typical evolution equation.Then the approximate solution for an original disturbed evolution equation is obtained using the asymptotic method.We point out that the series of approximate solution is convergent and the accuracy of the asymptotic solution is studied using the fixed point theorem for the functional analysis.     

车辆间大气激光移动通信调制方式研究

对大气激光移动通信的调制方式进行了研究,介绍了OOK、PPM、DPPM、DPIM及DH-PIM调制方式并分析了其各项性能指标,提出一种H-PPM调制方式并与其它调制方式进行了比较.该方式在继承标准PPM优良误码特性的同时,在接收端解调时不需要符号同步,简化了接收机的设计,降低了系统实现的难度.理论分析和仿真结果表明,此H-PPM调制方式可以满足移动车辆间短距离、高可靠性、小数据容量激光通信的需要.     

用于超声悬浮场可视化的光学全息相位倍增方法研究

基于二次曝光全息干涉测量原理,采用四倍相位倍增光路对声悬浮声压场分布进行了可视化研究.拍摄了给定模式的超声悬浮场在不同超声换能器激励电流时的光学全息图并进行光学再现,由再现光波的全息干涉条纹图样得到了反映声压场分布的光波波前相位变化,并进行了对比分析.结果表明,与无相位倍增光路相比,采用四倍相位倍增光路可使同一声压场的全息干涉条纹数目大大增加,测量灵敏度明显提高,为进一步研究声悬浮场声压分布提供了一种有效方法.     

ICF驱动器靶场环境温度分布特性实验

 对ICF驱动器靶场环境温度的分布特性进行了实验设计,利用PC-2WS多通道温度监测记录仪和PTWD-2A精密温度传感器进行了3个垂直截面的温度测量实验,应用MATLAB软件进行了数据处理,得出了靶场温度分布特性。实验结果表明：设计的暖通空调系统能够保持整个靶场环境温度的稳定,但由于内热源的影响在中间层靶室、编组站附近和工作人员活动频繁区域且由于下层安装设备集中处产生了较大局部环境温度梯度,因此,对这些区域需要加强温控措施。     

Sr位Nd掺杂对SrBi$lt;sub$gt;2$lt;/sub$gt;Nb$lt;sub$gt;2$lt;/sub$gt;O$lt;sub$gt;9$lt;/sub$gt;性能的影响及机理研究

采用传统固相法制备了（Sr_1-3x/2A_x/2Nd_x）Bi₂Nb₂O₉（x=0,0.05,0.1和0.2）陶瓷,并系统研究了Nd离子取代Sr离子对SrBi₂Nb₂O₉性能的影响及其作用机理.研究结果表明：Sr_1-3x/2A_x/2Nd_xBi₂Nb₂O₉的介电常数和介电损耗随温度变化的行为具有明显的离子松弛极化特征.Nd³⁺对Sr²⁺的部分取代,导致Sr_1-3x/2A_x/2Nd_xBi₂Nb₂O₉剩余极化强度P_r稍有下降,但其压电系数d₃₃却有所增加,根据铁电热力学理论,这是Nd³⁺对Sr²⁺取代导致材料介电常数增大所致.Sr_1-3x/2A_x/2Nd_xBi₂Nb₂O₉的居里温度（T_C）没有随Nd含量的增加而变化,拉曼光谱技术分析表明这是其NbO₆八面体畸变程度没有发生变化所致.Nd³⁺取代Sr²⁺提高了材料的介电常数ε_r、压电系数d₃₃、机电耦合系数K_p,同时降低了机械品质因数Q_m,但是谐振频率温度系数C值没有改变. 关键词： 压电陶瓷 介电性能 压电性能 拉曼光谱     

Analysis on FM-to-AM conversion induced by spatial filter in a high-power laser system

In order to avoid stimulated Brillouin scattering and smooth the final focal spot that reaches the D-T capsule, spectral broadening is essential. However, the modulation of spectral structure might result in frequency-to-amplitude modulation (FM-to-AM) conversion. The spatial filter pinhole is used to cut off the high-frequency transmission laser, and to ensure the desired pass. Improper parameter of pinhole would lead a negative impact. Using the spatial filter pinhole, we analyze the characteristic of intensity modulation using several pinholes of improper parameters. We then compare these results with the intensity modulation obtained from an experiment. Experimental diagnosis and design of an appropriate pinhole parameter would be highly beneficial to the field of high-power lasers.     

厚度诱导的YBa2Cu3O7-δ超导薄膜剩余应力及临界电流变化

本文通过脉冲激光沉积法制备了不同厚度(80nm、320nm、1000nm和2000nm)的YBa2Cu3O7-δ(YBCO)超导薄膜,对它们的剩余应力和临界电流特性进行了对比研究.通过系列的激光显微Raman光谱和磁化曲线测量分别获得了薄膜剩余应力和磁化临界电流密度(Jc)对薄膜厚度的依赖关系.结果显示超导薄膜内剩余应力越小,Jc越高.对于中等厚度的薄膜样品(320nm和1000nm),其膜内剩余应力较小,同时由其特征的磁通匹配场大小推知在该厚度范围内的样品具有较高的线性缺陷密度,从而显示出较高的Jc值.     

Vaidya-Bonner黑洞的费米子隧穿

运用费米子隧穿的理论,对Vaidya-Bonner黑洞的费米子Hawking辐射进行研究.使用随动坐标变换,并假设γ^μ矩阵的一个合理形式,从而得到了Vaidya-Bonner黑洞的自旋为1/2的粒子的隧穿辐射行为. 关键词： Vaidya-Bonner黑洞 Dirac方程 Hawking辐射 费米子隧穿     

Thermal annealing behaviour of Al/Ni/Au multilayer on n-GaN Schottky contacts

Recently GaN-based high electron mobility transistors (HEMTs) have revealed the superior properties of a high breakdown field and high electron saturation velocity. Reduction of the gate leakage current is one of the key issues to be solved for their further improvement. This paper reports that an Al layer as thin as 3 nm was inserted between the conventional Ni/Au Schottky contact and n-GaN epilayers, and the Schottky behaviour of Al/Ni/Au contact was investigated under various annealing conditions by current--voltage (I--V) measurements. A non-linear fitting method was used to extract the contact parameters from the I--V characteristic curves. Experimental results indicate that reduction of the gate leakage current by as much as four orders of magnitude was successfully recorded by thermal annealing. And high quality Schottky contact with a barrier height of 0.875 eV and the lowest reverse-bias leakage current, respectively, can be obtained under 12 min annealing at 450°C in N₂ ambience.