PERIODIC DYADIC GREEN''S FUNCTION FOR FIELD ANALYSIS IN EMC CHAMBER

Herein a novel Dyadic Green's Function (DGF) is presented to calculate the field in ElectroMagnetic Compatibility (EMC) chamber. Due to the difficulty of simulating the whole chamber environment, the analysis combines the DGF formulation and the FEM method, with the latter deals with the reflection from absorbers. With DGF formulation for infinite periodic array structures, this paper investigates electromagnetic field in chamber with truncated arrays. The reflection from the absorber serves as the virtual source contributing to the total field. Hence the whole chamber field calculation can be separated from the work of absorber model set-up. Practically the field homogeneity test and Normal Site Attenuation (NSA) test are carried out to evaluate the chamber performance. Based on the method in this paper, the simulation results agree well with the test, and predict successfully the victim frequency points of the chamber.     

The sinuous antenna-A dual polarized feed for reflector-based searching systems

The sinuous antennas have a numerous applications in military and civil systems such as direction finding systems and reflector feeds due to their superior broadband characteristics and simultaneous polarization capability. In this paper, design, construction and measurements of planar sinuous antennas are investigated for 1–5 GHz frequency range. Feeding sections of this antenna are realized by using microstrip tapered baluns. We have determined the microstrip tapered balun dimensions using Ansoft HFSS-simulation program. The performances of the manufactured antenna are measured using HP vector network analyzer. Polarization patterns and return loss characteristics of the designed antenna that have been measured in anechoic chamber, are presented.     

P-channel Ge/Si Hetero-nanocrystal Based MOSFET Memory

The charge storage characteristics of P-channel Ge/Si hetero-nanocrystal based MOSFET memory has been investigated and a logical array has been constructed using this memory cell. In the case of the thickness of tunneling oxide T_ox=2nm and the dimensions of Si- and Ge-nanocrystal D_Si=D_Ge=5nm, the retention time of this device can reach ten years(~1×10~8s) while the programming and erasing time achieve the orders of microsecond and millisecond at the control gate voltage |V_g|=3V with respect to N-wells, respectively. Therefore, this novel device, as an excellent nonvolatile memory operating at room temperature, is desired to obtain application in future VLSI.     

高分辨方位估计方法的稳健性研究

基于特征分解理论的子空间类高分辨方位估计方法是目前阵列信号处理领域的研究重点。与波束形成法相比，子空间类法的特点为估计精度高和分辨能力强。但是这类高分辨方法对阵列模型失配十分敏感，存在阵列误差时其估计性能明显下降。文章通过仿真和实验深入研究了MUSIC、Johnson和Mini-Norm等子空间类高分辨方位估计方法的稳健性问题，分析了一定信噪比条件下阵列误差对上述三种方法估计结果的影响程度。研究结果表明，MUSIC法和Johnson法的估计性能相当，而Mini—Norm法的稳健性明显高于MUSIC法和Johnson法，分辨能力和估计精度较好，具有良好的工程应用前景。     

高度有序多孔氧化铝模板的制备工艺与生长机制的研究

采用二次氧化法制备出高度有序的多孔氧化铝模板，结合扫描电镜和原子力显微镜对其结构、形貌进行观察和表征。研究了铝箔预处理和温度等对多孔氧化铝模板孔洞有序性的影响，讨论了有序孔洞的自组织生长机理。     

Computationally efficient direction-of-arrival estimation of non-circular signal based on subspace rotation technique

In order to solve the problem that the high computational burden of the multiple signal classification algorithm of non-circular signal (NC-MUSIC) in direction-of-arrival (DOA) estimation,a novel computationally efficient DOA estimation algorithm based on subspace rotation technique was proposed.Firstly,the partitioning of noise subspace matrix and the subspace rotation technique (SRT) were used to construct a new reduced-dimension noise subspace.Then,the two-dimensional peak searching was converted to the one-dimensional peak searching on the basis of the separation of variables and the orthogonality between the new reduced-dimension noise subspace and the space spanned by the columns of the extended manifold matrix.The proposed algorithm can enhance the computational efficiency by means of the conversion of the two-dimensional peak searching into the one-dimensional peak searching and the removal of redundant computations.Theoretical analysis and simulation results show that the proposed algorithm can reduce the computational complexity to less than 5% as compared to NC-MUSIC algorithm on the premise of ensuring the accuracy of DOA estimation.Especially,the efficiency advantage of the proposed algorithm is more obvious in scenarios where the large numbers of sensors are required.     

以循环移位控制为基础的相控阵天线快速测量方法研究

为了解决相控阵天线快速测试问题,本文研究了一种相控阵天线测量的新方法。该方法中相控阵天线和测试探头均不动,利用相控阵天线中各移相器的移相状态可循环移位控制的特点和相控阵天线一些已知可信的信息,从而使测量具有极高的效率。文中对一相控阵天线模型采用该测量方法的测量全过程进行模拟,验证了该方法的正确性和高效性。     

SVM自适应波束成形算法

在天线阵列过载,以及强干扰与期望用户信号夹角过近的情况下,传统的线性阵列信号处理算法,如MMSE(minimum mean-squareerror)、NLMS(Normalized Least Mean Squares)等表现并不理想。SVM(SupportVectorMachine)是机器学习领域的最新成果,有较强的泛化能力,收敛快以及低复杂度等优点。本文提出了在上行波束成形中使用SVM算法,提高空域滤波的分辨率,与其他相关算法相比较,系统性能有了明显的改进。     

冗余磁盘阵列的故障容错分析

本文在介绍冗余磁盘阵列(RAID)的故障容错机理之后,着重研究了设备故障对RAID系统可靠性的影响.其平均持续正常工作时间和系统在线修复设备故障容许的平均间隔时间的计算结果表明,只要在一定的容许时间内替换或修复故障磁盘,系统可保持持续正常工作状态.     

射频激励扩散型冷却阵列波导CO2激光器技术

本文介绍了目前国内外研究者们提出的各种射频激励相干阵列波导ＣＯ２激光器技术，讨论了射频激励相干阵列波导ＣＯ２激光器技术的一个研究方向。