线性相位二维跳耦型数字滤波器组设计及其在图像子带编码中的应用

本文提出了一种新的二维递归数字滤波器组－二维跳耦型数字滤波器组的设计与实现方法。这种数字滤波器组的特点为：因果型－可用于实时图像分解与重构；线性相位－可避免传统的二维ＩＩＲ滤波引起的图像的相位畸变，非线性条件下稳定－有限字长实现二维数字滤波器组时，不存在溢出或极限环振荡，实际的图像处理实验证明，本文提出的设计理论及实现方法是正确的，有效的，可行的。     

语音信号的滤波设计

在现代通信系统中,噪声会不可避免地掺杂在其中,最通用的方法就是利用滤波器来滤除这些杂波噪声。基于此,设计了FIR与IIR数字滤波器来消除语音信号中的噪音,并且使用MATLAB对其进行仿真分析,从仿真结果中可以清晰地看出两种滤波器对语音信号的处理效果。     

基于FPGA的高速高阶FIR数字滤波器的设计

在数字滤波器设计与应用当中,相比于以牺牲线性相位频率特性为代价的无限冲击响应(IIR)数字滤波器,有限冲击响应(FIR)数字滤波器不仅保证了精确严格的线性相位特性,并且结构简单稳定。但在实现相同的设计指标时,有限冲击响应需要更高的阶数,为满足高速高阶数字滤波器设计,文章提出一种改进的分布式算法。该算法利用主流现场可编程逻辑门阵列(FPGA)芯片的多相分解结构和流水线技术,采用多路复用加法器对数据进行预相加,减少传统分布式结构的查找表规模。利用Matalb仿真设计,Quartus II编译测试,并下载到现场可编程门阵列(FPGA)中进行运行分析,结果显示文章的方法有效地减少了滤波器对硬件资源的消耗,能够较好地实现高阶的FIR滤波器。     

基于MATLAB的数字基带传输的FIR滤波器的设计

为了消除数字基带传输系统中的码间串扰,可将FIR数字滤波器应用于消除码间串扰的升余弦滚降特性低通滤波器的设计中。文中简要介绍了FIR数字滤波器的特征,给出了运用MATLAB实现FIR数字滤渡器的设计与仿真方法．同时给出了将设计结果应用于消除码间串扰的数字基带传输系统中操作过程。     

最大SNR线性相位FIR数字滤波器的设计

本文介绍了用于最大信噪比（ＳＮＲ）有限脉冲响应（ＦＩＲ）数字滤波器设计的梯度算法。我们注意到，对特征值梯度的确定产东能从任何起始点得出决体最大值。文章中研究了用所提出的方法设计的线性相位低通、高通和带通滤波器的特性。既使当渺茫皮器长度相当小时，最大信噪比滤波器也能够保持相当好的滤波性能。该滤波器对已知功率谱的稳定信号和稳定噪声组成的混合信号处理方面具有较强的优越性。     

基于DSP的自适应噪声消除

将基于DSP的自适应滤波器用于通信系统,利用自适应滤波器的通带始终和输入信号频带宽度自适应相匹配的特点,实现通信系统中的噪声消除.实践证明较好地实现了噪声消除,能够达到改善通信质量,增加通信距离的效果.     

音圈电机激光扫描器的线性扫描控制

建立了音圈电机驱动的激光扫描器的模型并进行了参数辨识。由于音圈电机驱动的激光扫描器反馈回路的高频噪声较大,利用光电精密跟踪的传统方法,如改进型PID控制算法,以及理想闭环特性(最佳二阶特性)的逆向设计方法,系统并不能稳定工作,易振荡。分析了造成振荡的原因,采用前馈复合控制方法,避开了振荡因子同时又减小了稳态误差,解决了稳态误差和振荡的矛盾。结合反馈回路噪声大的特点,将滤波器加入反馈回路中,使激光扫描器不仅能稳定工作,消除了扫描时候的抖动,同时减少了线性扫描时候的磁滞现象。     

基于FPGA的数字上／下变频SOPC的设计与实现

在宽带中频软件无线电通信系统中，数字上变频（DUC）及下变频（DDC）是其核心技术之一。本文介绍了数字上／下变频的原理，给出了一种基于现场可编程逻辑器件（FPGA）的数字上／下变频片上可编程系统（SOPC）的设计方案，并重点讨论了有限冲击响应（FIR）滤波器的设计、内插器和抽取器的实时处理结构一多相滤波器结构以及数控振荡器（NCO）的实现。在Xilinx公司的FPGA集成开发软件ISE7．1中编写了相应的通信程序，并对整个系统进行了实验验证。结果表明系统稳定可靠，方案是可行的。     

数字接收机中位同步器的研制

位同步器在通信系统中有重要的作用,直接影响接收机的性能。基带成形滤波器对信号频谱进行压缩时,利用个位同步器消除码间干扰和提高系统频带利用率。本文为升余弦成形滤波器的数字接收机设计出一种简单可行的位同步器,并通过仿真验证了其简单性和可行性。     

基于单自由度振动模型的IIR数字滤波器设计

无限冲击响应(IIR)数字滤波器设计通常需要先设计S域滤波器,再变换到Z域。为简化IIR数字滤波器的设计过程,本文提出利用单自由度系统(SDOF)模型直接设计IIR数字滤波器的方法,包括低通、带通、高通、带阻等。仿真结果表明设计过程直接、简单,滤波器参数不需要随采样频率而变,具有良好特性,是一种设计IIR数字滤波器的简便易用的新方法。     

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.     

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.     

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.