射频窄带信号时差估计算法研究

研究了定位中的射频窄带信号时差估计问题,给出时差估计的信号模型,在研究传统广义相关时差估计算法及基于希尔伯特变换时差估计算法基础上,提出了广义相关希尔伯特差值时差估计算法。通过仿真实验,给出估计性能曲线,与广义相关法及希尔伯特变换时差估计算法相比,仿真结果表明该算法具有较好的估计性能。     

两站基于角度和时差信息的伪线性卡尔曼滤波算法及其改进

建立了两站基于角度(DOA)和时差(TDOA)信息的伪线性观测模型,基于该模型提出了匀速运动目标的伪线性卡尔曼滤波(PLKF)算法。仿真结果表明该算法的稳健性要高于扩展卡尔曼滤波(EKF)算法,当观测误差较小时,PLKF算法的定位精度要高于EKF算法;当观测误差较大时,其定位精度低于EKF算法。对此文中结合两种算法的优点,提出了改进算法,以同时提高算法的定位精度和稳健性。     

基于匹配相关法的罗兰C信号周期识别

在分析比较了国内外的罗兰C周期识别算法上,提出了一种利用匹配相关进行周期识别的方法。从理论上讲,由于已知罗兰C信号的波形,采用这种方法是罗兰C信号的最佳接收,它能有效减少白噪声的干扰。在此基础上改进的相关法周期识别能够解决强噪声环境下的跳周问题。实验结果表明,该方法能够有效检测到标准过零点,周期识别精度可达0.1μs。     

基于时差定位解算的目标跟踪处理

针对三站时差定位系统的目标跟踪问题,推导了时差定位解算过程和定位协方差估计方法,研究了“先时差定位解算、后卡尔曼滤波处理”的跟踪处理方法。计算机仿真实验表明,该处理算法跟踪精度与无迹卡尔曼滤波基本相当,由于其避免了非线性近似计算导致的发散问题,处理稳健性更好,适合在实际工程中应用。     

基于循环互相关的宽带信号时差估计

研究了定位中的宽带信号时差估计问题，给出了时差估计信号模型，分析了信号的循环相关特性，提出了基于宽带信号循环互相关的时差估计算法。最后采用计算机进行了仿真实验，给出了估计性能的曲线，并和广义相关算法进行比较，仿真实验表明本文所提算法具有较好的估计性能。     

基于LabVIEW的某导航设备卡尔曼滤波方位解算修正技术

某导航设备信号常使用卡尔曼滤波算法进行方位解算。为改良卡尔曼滤波噪声系数，确保算法在较短的时间内准确解算设备信号方位值，提出一种基于LabVIEW 的卡尔曼滤波方位解算修正技术，通过LabVIEW 快速构建信号模型和卡尔曼滤波方位解算模型，完成对卡尔曼滤波初始参数的修正。经测试，该技术有效缩短卡尔曼滤波噪声系数修正时间，可应用于实装工程。     

基于时差和时差变化率的宽带信号单站无源定位方法

当目标为宽带信号时,现有单站无源定位方法需要的参数难以获取。而时差和时差变化率是一种宽窄带都适用的观测量。因此,在分析时差和时差变化率所包含目标信息的基础上,建立了一种新的单站对宽带信号源的定位模型,并利用粒子滤波算法对该模型进行滤波处理。仿真实验表明了该方法的有效性。     

一种低轨双星高脉冲重复频率雷达信号的定位模糊消除算法

针对低轨(LEO)双星到达时间差(TDOA)定位系统中雷达信号的定位模糊问题,该文分析了高重频信号的模糊特性,演示了虚假定位点的产生过程,提出一种基于时差序列变化趋势匹配(VTMT)的定位模糊消除算法。在测量时差序列与定位结果对应的理论时差序列之间的残差近似服从正态分布的条件下,通过两个序列的欧式距离作为相似程度衡量依据,筛选出测量时差线与理论时差线最为接近的定位点作为目标辐射源真实位置。校验台测试信号验证了该算法的有效性。仿真结果表明,该算法能够显著提高无模糊定位概率,对长基线时差定位系统中雷达信号的定位具有较高的应用价值。     

卡尔曼滤波在目标跟踪中的研究与应用

卡尔曼滤波算法是现阶段雷达信号处理中最常用的跟踪算法,结合雷达跟踪的空中目标的实际情况,针对目标运动模型中的线性运动和非线性运动模型,分别设计了两种模型,并利用马尔可夫状态转移矩阵实现交互多模算法。最后对交互多模型卡尔曼滤波算法进行了Matlab仿真及结果分析。     

基于虚拟仪器的罗兰C监测系统的设计与实现

为提高罗兰C信号监测效率,克服依据单一信息进行诊断的不足,本文在NI PXI平台上设计了一种罗兰C信号监测系统。首先基于PXI-5922和PXI-8336构建了该系统,其次给出了罗兰C信号监测的具体方法,最后通过定点监测实验,与监测站结果对比,结果显示,基于LabVIEW的罗兰C信号监测系统的诊断准确度高、扩展性强、软件开发和升级便利。     

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.