分布式嵌套阵列及其DOA估计

提出了一种分布式嵌套阵列天线结构,由两个相互独立的四级嵌套子阵构成。两个子阵间存在一个基线长度,且满足一定条件。对该阵列天线接收到的信号进行高阶累积量和Khatri-Rao积运算可以得到三个完全相同的均匀直线阵列天线结构。针对新得到的阵列天线结构,使用基于空间平滑技术的双尺度酉旋转不变子空间( ESPRIT)波达方向( DOA)估计算法对信号进行DOA估计。该方法可以有效地提高阵列天线的自由度,进而达到提高估计精度的目地。仿真结果证明了基于所提出阵列天线结构的DOA估计方法的有效性。     

基于高阶循环累积量的OFDM子载波盲估计

该文针对通信对抗和OFDM信号解调的实际应用,提出一种利用高阶循环累积量估计OFDM信号子载波的方法。由于高阶循环累积量能有效抑制平稳噪声和非平稳高斯噪声,通过理论分析可证明在上述噪声背景下,子载波采用2/4PSK调制的OFDM信号的特定四阶循环累积量仅在子载波处存在,因此可以通过检测此循环频率实现子载波的估计。该算法还可推广到采用星形QAM和高阶PSK调制的OFDM信号。仿真实验验证了该算法的有效性。     

基于联合对角化的近场源三维参数估计

提出了一种基于联合对角化的近场源频率、到达角（DOA）和距离的联合估计算法。首先利用二阶统计量构造白化矩阵,再基于白化后的接收数据构造一组高阶累积量矩阵,利用联合对角化方法来得到高阶累积量矩阵的对角结构信息以及对角化矩阵来分别估计阵列流形和信号源的频率,进而由阵列导向矢量结合对应的信号源频率联合估计信号源的到达方向和距离。与基于高阶累积量的类 ESPRIT方法相比,算法可以提高阵元利用率,具有更好的估计效果,同时不需要谱峰搜索且各参数自动配对,计算机仿真结果验证了该方法的有效性。     

直接序列扩频信号的载频提取与扩频序列的盲估计

在高阶统计理论的基础上，提出了利用四阶累积量来提取直接序列扩频信号（DS-SS）的载频，并结合DS-SS的累积技术与特征向量分析的方法，对扩频序列的盲估计算法进行了改进。仿真结果表明该方法鲁棒性强，可以工作于-20dB信噪比的环境下。     

基于高阶循环累积量的QAM载波频率估计

利用通信信号的循环平稳特性,通过对QAM信号高阶循环累积量的研究,提出了一种基于高阶循环累积量的星形和方形QAM载波估计算法。并且对该算法进行了理论分析,仿真结果证明,该算法的正确性和有效性。     

基于高阶累积量矩阵组正交联合对角化的高分辨方位估计方法

该文提出了一种基于高阶累积量矩阵组正交联合对角化的高分辨方位估计方法。该方法构造了一组高阶累积量矩阵共同来辨识阵列流型矩阵的列空间,进而进行DOA估计。并通过对高阶累积量矩阵组进行联合对角化,得到联合对角化矩阵和对角化后的矩阵组,并重新定义了空间谱。新方法可以处理相干声源,适用于有色噪声环境,且较仅使用单个高阶累积量矩阵的算法具有更高的分辨力,更低的均方根误差和更高的鲁棒性。     

一种单接收天线下的空时分组码识别方法

该文针对全盲条件下单接收天线的空时分组码(STBC)识别问题,提出一种基于四阶累积量识别方法。使用接收信号的四阶累积量作为特征参数,利用高阶累积量对零均值高斯噪声不敏感的特性,首先求取各种STBC的四阶累积量理论值,再对采样信号四阶累积量进行区间检测,从而实现STBC的识别。该算法不需要信道信息和噪声参数,仿真结果表明,该算法在单天线条件下性能较好。     

基于四阶累积量的DOA估计方法

从一个统一的角度来研究基于高阶累积量的高分辨阵列信号处理方法，用四阶累积量构造了一个较通用的累积量矩阵，该矩阵符合MUSIC算法的结构，从而可进行DOA（Directionof Arrival）估计。对于这种方法在阵列信号处理中的应用，通过计算机仿真与基于二阶矩的MU—SIC算法进行了较全面的比较。仿真结果表明，该方法在高斯噪声中具有良好的统计性能，是实现高分辨方位估计的有效方法，     

四阶累积量谱线增强方法的改进仿真研究

为提高自适应谱线增强器跟踪性能,减小高阶累计量的计算量,综合了变步长算法与变符号函数法（ISA）算法的优点,在高阶累积量的能量幂函数变步长极性迭代自适应谱线增强算法的基础上,首次提出了一种计算正弦信号基于高阶累积量变步长ISA算法的迭代自适应谱线增强方法。该方法用输入信号的能量幂函数作变步长来改善跟踪性能,用非输入信号的分段性限幅函数来减小高阶累计量的计算量。仿真结果表明该算法在抑制高斯噪声和非高斯对称分布（拉普拉斯）噪声上优越于基于能量幂函数变步长极性迭代自适应谱线增强算法,能稳定保持信噪比提高3 dB。     

基于累积量的时差频差联合估计算法

介绍了无源定位中二阶累积量和高阶累积量的时差频差联合估计（TDOA/FDOA）算法,分析了噪声相关性对二阶累积量和四阶累积量的时差频差联合估计算法的影响。仿真结果表明,这一方法是切实可行的。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.