A Novel Low-Dimensional Method for Analytically Solving Partial Differential Equations

This paper is concerned with a low-dimensional dynamical system model for analytically solving partial differential equations (PDEs). The model proposed is based on a posterior optimal truncated weighted residue (POT-WR) method, by which an infinite dimensional PDE is optimally truncated and analytically solved in required condition of accuracy. To end that, a POT-WR condition for PDE under consideration is used as a dynamically optimal control criterion with the solving process. A set of bases needs to be constructed without any reference database in order to establish a space to describe low-dimensional dynamical system that is required. The Lagrangian multiplier is introduced to release the constraints due to the Galerkin projection, and a penalty function is also employed to remove the orthogonal constraints. According to the extreme principle, a set of ordinary differential equations is thus obtained by taking the variational operation of the generalized optimal function. A conjugate gradient algorithm by FORTRAN code is developed to solve the ordinary differential equations. The two examples of one-dimensional heat transfer equation and nonlinear Burgers’ equation show that the analytical results on the method proposed are good agreement with the numerical simulations and analytical solutions in references, and the dominant characteristics of the dynamics are well captured in case of few bases used only.     

基于双向联想记忆网络的航空雷达在线入侵诊断方法研究

针对传统的航空雷达网络面临的入侵威胁,以及雷达网络存在的入侵诊断检测效率较低,数据匹配速度较慢等问题,提出了一种基于双向联想记忆网络的航空雷达在线入侵诊断方法,构建航空雷达在线入侵诊断模型,对航空雷达网络中的外部数据进行预处理,并获取数据特征以及数据特征的可辨识属性矩阵和决策辨识函数,计算测试参数集的所有特征向量,从而使入侵检测算子的匹配量减少,以此提升数据匹配效率,实现对外部入侵数据的过滤检测,从而对雷达数据网络进行在线监控,有效抵御外部异常数据的入侵,保证了航空雷达网络的安全性;仿真结果表明文章方法有效提高了航空雷达网络的在线数据检测匹配速度,诊断准确率达到93.3%,且对航空雷达的入侵诊断检测效率、误报率、漏报率等方面都有明显改善。     

以二乙烯硫/砜基为中心的新型电荷转移分子双光子吸收特性

理论研究分子结构与双光子吸收性质之间的关系对于指导实验者设计与合成功能分子材料具有重要意义. 在杂化密度泛函水平上, 利用响应函数方法, 计算了一类以二乙烯硫/砜基为中心的新型电荷转移分子的双光子吸收截面, 并在相同计算水平上, 与联苯乙烯类强双光子吸收分子做了比较; 以新型电荷转移分子为基础, 利用异构效应, 设计出了可以增强双光子吸收强度的分子结构. 研究表明, 在可应用波长范围内, 该系列分子表现出较强的双光子吸收响应, 与相似共轭长度的强双光子吸收分子具有相同量级的双光子吸收截面; 二乙烯硫/砜基在分子中心作为吸电子基团可以形成有效的电荷转移分子; 改变咔唑基的连接方式可以有效提高双光子吸收截面. 该研究为实验合成新型双光子吸收分子材料提供了理论依据.     

倾斜波动壁面上液膜表面波演化特性的影响

对倾斜波动壁面上流体表面波的演化规律进行了研究. 考虑壁面形状为正弦波动壁面的情况, 分析液膜流动的线性稳定性, 并研究不同倾斜角度下扰动波波形随时间的演化情况及流经不同壁面形状时扰动波的波形变化. 对整体的波形结构分析可知, 随着时间的演化, 扰动波的演化过程呈现为更大波长的近周期变化规律, 与平板上的流动结构对比发现波动情况变得更加复杂; 当液膜流经波动壁面时, 扰动波在空间上不再呈现规律性变化, 且随着壁面倾斜角度的增加, 扰动波的振幅逐渐增加; 在相同的壁面倾角下, 波动壁面上的扰动波振幅大于平板壁面的扰动情况, 且波形扭曲程度更明显; 随着Re的增加, 扰动波振幅逐渐增加, 其对应波形的扭曲程度加深, 且随着壁面振幅的增加, 静态波振幅及扰动波振幅均随之增加, 对应的行进波周期不变. 最后, 分析了壁面倾斜角度对流动稳定性的影响.     

无人机微波着陆引导系统坐标变换算法研究实现

为了实时且精确地获取飞机相对于着陆点的位置坐标,在深入分析机场场地位置几何信息和地面设备制导信息并建立坐标变换测量方程的基础上,提出了一种基于坐标系旋转的旋转坐标迭代解算算法;该算法通过坐标系的旋转消除了飞机纵轴方向上的位移,而后研究其具体迭代解算过程,并通过仿真进行算法性能分析;将所提出的旋转坐标迭代解算算法在TMS320F2812DSP上进行实现,并利用集成开发环境(CCS)进行调试与仿真;结果表明:旋转坐标迭代解算算法收敛快速且精确度高,DSP实现的旋转坐标迭代解算算法所得坐标值与软件仿真结果基本一致,满足系统性能指标要求,对于无人机着陆制导信息的获取具有实用价值。     

Novel optical add-drop multiplexer based on dual racetrack resonators

In this paper, we designed and fabricated a four-channel optical add-drop multiplexer (OADM) based on dual racetrack resonators. The size of the fabricated device is only 2400 μm × 500 μm. The fabricated device can effectively and perfectly realize the signals upload and download. The free spectral range (FSR) of OADM is about 15.2 nm. We take the spectral responses near 1555 nm as an example. When the device acts as an optical drop multiplexer, the minimum insertion loss is 4.481 dB and the maximum extinction ratio is 31.931 dB. The maximum adjacent channels crosstalk is -9.845 dB. When the device acts as an optical add multiplexer, the minimum insertion loss is 0.944 dB and all of the extinction ratios are bigger than 25 dB. The maximum crosstalk is -16.531 dB which indicates the crosstalk can be neglected.     

非晶硅薄膜太阳能电池的紫外激光刻蚀工艺

为提高电池的光电转换效率,通过改善激光刻蚀工艺,采用355 nm紫外纳秒激光分别进行了ZnO：Al薄膜（AZO）刻蚀（P1）、非晶硅薄膜（-Si）刻蚀（P2）和背电极刻蚀（P3）研究。采用万用表测量P1隔离电阻,采用电子扫描显微镜（SEM）和三维激光扫描仪测量刻槽的微结构和三维成像,激光拉曼散射光谱检测非晶硅薄膜刻蚀边缘的晶化。实验结果表明,当刻蚀速度600 mm/s,重复频率40 kHz,功率1.74 W的紫外激光刻蚀ZnO：Al薄膜时,刻槽的隔离效果最佳,达20 M; 紫外激光刻蚀能够有效地减小激光热效应引起的热影响和刻槽边缘的晶化范围,提高非晶硅薄膜电池的性能。     

Terahertz surface plasmon polaritons in textured metal surfaces formed by square arrays of metallic pillars

In this paper, we investigate numerically the characteristics of surface plasmon polaritons (SPPs) sustained by two-dimensional arrays of metallic pillars protruding out of planar metal surfaces at terahertz (THz) frequencies. Various shapes of the pillars are analyzed, and it is shown that the pillar shape only has weak influence on the dispersion of spoof SPPs. However, the loss of spoof SPPs is closely dependent on the pillar shape. It is also shown that spoof SPPs on textured surfaces with pillars can exhibit much better confinement than those on pierced surfaces with holes.     

亚波长孔阵列的太赫兹波异常透射研究

利用太赫兹时域光谱（THz-TDS）系统,在5—300 K温区下测量了在厚度约200 nm的金属Nb薄膜刻蚀的亚波长圆孔阵列的异常THz波透射情况.实验结果表明,在03—2 THz波段,具有亚波长孔阵结构的金属Nb薄膜的异常透射现象波谱的峰位置与CST（computer simulation technology）软件仿真模拟的结果一致,峰值随温度降低有逐渐增强的趋势. 关键词： 亚波长孔阵列 THz时域光谱技术 异常透射     

Co与Cu掺杂ZnO薄膜的制备与光致发光研究

采用溶胶-凝胶旋涂法在玻璃衬底上制备了Co, Cu单掺杂及Co,Cu共掺杂ZnO薄膜.用金相显微镜观察了Co与Cu掺杂对ZnO薄膜形貌的影响.X射线衍射（XRD）研究揭示所有ZnO薄膜样品都存在（002）择优取向,在Cu单掺的ZnO薄膜中晶粒尺寸最大.对所有样品的室温光致发光测量都观察到较强的蓝光双峰发射和较弱的绿光发射,其中长波长的蓝光峰和绿光峰都能够通过掺杂进行控制.对不同掺杂源的ZnO薄膜发光性能进行了分析,认为蓝光峰来源于电子由导带底到锌空位能级的跃迁及锌填隙到价带顶的跃迁,绿光峰是由于掺杂造成的 关键词： ZnO薄膜 溶胶-凝胶 Co Cu掺杂 光致发光