分布式子带自适应滤波算法

为了解决分布式最小均方算法在输入信号相关性较高时收敛速度较慢、分布式仿射投影算法计算复杂度较高等问题,本文提出了两种分布式子带自适应滤波算法,即递增式和扩散式子带自适应滤波算法.分布式子带自适应滤波算法将节点信号进行子带分割来降低信号的相关性,从而加快收敛速度.由于用于子带分割的滤波器组中包含了抽取单元,所以分布式子带自适应滤波算法和对应的分布式最小均方算法的计算复杂度相近.仿真结果表明,与分布式最小均方算法相比,分布式子带自适应滤波算法具有更好的收敛性能.     

一种多路并行盲搜索的空时二维抗干扰算法

针对卫星导航抗干扰中传统的空时自适应处理算法运算量大、处理速度较慢的问题,在介绍多级维纳滤波基本原理的基础上,提出了一种多路并行的盲搜索空时二维抗干扰自适应处理算法。该方法采用多级维纳滤波降维处理的方法求解信号子空间和干扰子空间,从而使输出信号的信干噪比达到最优,实现干扰的有效抑制。仿真结果表明,该算法具有较好的抗干扰性能,且运算量较低,有较好的工程应用前景。     

基于经验模态分解的宽带阵列DBF研究

已有研究对宽带阵列信号的子带分解处理中子带划分是固定的,各子带内信号数分布不均衡。该文研究了子带自适应划分的模态域宽带自适应阵列算法,提出将经验模态分解(EMD)融合于线性约束最小方差(LCMV)算法中,EMD把多分量信号自适应地分解成多阶内蕴模态函数(IMF),突出了信号的局部瞬间特征,两者结合既满足了LCMV的窄带信号要求又充分发挥了EMD自适应的特点,解决了阵元数目受到严格限制时,宽带阵列处理自由度不足、抗干扰性能下降的问题,在强干扰环境和各信号强度相差较大时也能有效检测出较弱信号。与基于FFT的子带分割相比,无需预先划分模态函数的频段,阵元数目受限时增加了处理自由度。仿真表明3阵元强干扰条件下改善增益11dB。     

战术数据链空时联合抗干扰技术

针对战术数据链在复杂电磁环境下性能受限的问题,提出基于非标准构型阵列天线的战术数据链空时联合抗干扰技术。该技术在常规导向矢量获取方法失效时,通过设计引导信号,结合盲自适应抗干扰算法进行干扰信号的抑制和引导信号的重构,实现对干扰方向调零抑制并保持通信信号的正常接收。仿真结果表明,通信信号经过空时联合抗干扰处理后,在干扰方向形成的零陷超过-30 dB,大大抑制了干扰方向的信号,保存了信号方向的信号。     

一种基于正交加权约束的GPS抗干扰盲算法

针对GPS信号C/A码的周期重复特性,联合CAB算法和子空间技术提出了一种盲自适应波束形成方法。该算法通过将CAB算法的权矢量和控制矢量约束到干扰导向矢量的正交补空间内,使之在期望信号方向上产生高的增益,并在干扰方向上形成零陷。该方法具有盲处理、收敛速度快和低计算复杂度等优点。仿真结果证明了算法的有效性。     

一种改进的基于ATF算法的直扩通信干扰抑制技术

提出了直扩通信中一种改进的基于ATF（自适应时频）算法的干扰抑制方法。对原有算法进行了优化并给出了相应的自适应去干扰算法。采用自适应滤波技术取代子带剔除法,自适应地跟踪窄带干扰,改善了有用信号的丢弃情况,有效地抑制了窄带干扰。分析和仿真结果表明,基于ATF算法的自适应小波包时频干扰抑制方法比传统的子带剔除法在性能上更为优越,干扰定位速度也较快,干扰抑制能力强。     

用于阵列处理的信号子空间法

介绍一种阵列处理中采用的自适应干扰对消新算法。该算法将信号子空间法与基于目标函数（输出信号干扰比的一种尺度）的自适应法结合在一起，其最大特点是：与其它信号子空间法相比的一种尺度无需阵列校准，从而具有经济性、灵活性等优点。     

MIMO系统中基于干扰子空间投影的盲空时多用户检测算法

该文针对多天线码分多址系统,提出了一种盲空时多用户检测算法。该算法结合空域、时域二维信息,利用Alamouti空时分组码与MIMO信道的结构特征,通过跟踪干扰子空间对多天线信道进行估计。在此基础上,通过将接收信号投影到干扰子空间的正交补空间上,实现了抑制多址干扰的空时多用户检测。该算法不仅能够自适应地跟踪信道的变化,且具有较低的算法复杂度。仿真结果表明该算法能够有效地抑制多天线码分多址系统中的多址干扰,改善系统的性能。     

基于改进快速子空间迭代跟踪的部分自适应STAP算法

针对部分空时自适应(STAP)处理的特征值分解(EVD)影响杂波抑制的实时处理性能,提出了基于改进快速子空间迭代跟踪(PAST)的部分自适应STAP算法.该方法首先在PAST处理的基础上,对正交PAST方法进行改进,得到改进后的PAST(MPAST)方法;然后将MPAST方法应用于计算部分自适应STAP算法的特征子空间,从而有效提高STAP算法的收敛速度和降低自适应权矢量计算的运算量.仿真数据和MCARM实测数据分析表明,该方法能有效抑制待检测距离单元的杂波,并能在低计算复杂度下显著提高STAP处理的收敛速度.     

基于空时二维协方差矩阵修正的波束形成算法

在实际应用环境中,信源和阵列传感器等存在误差,假设期望信号的导向矢量与真实信源导向矢量的失配会导致阵列波束形成器把期望信号当作干扰来加以抑制。针对信号匹配误差导致自适应波束形成性能下降的问题,提出了一种基于空时二维协方差矩阵修正的波束形成算法,利用空时结构对宽带幅相误差校正的特性,对空时二维协方差矩阵进行重构,并对修正协方差矩阵进行特征值分解,分离出信号加干扰子空间,将失配导向矢量投影可使期望信号与噪声子空间严格正交,最后求解算法最优权值。算法有效改善了波束形成的输出信噪比,计算机仿真验证了理论分析的正确性和算法的稳健性。     

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.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

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.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.