多幅非均匀噪声图像的联合去噪法的应用及仿真

小波去噪是小波变换的重要应用领域之一。对多幅被空间非均匀噪声污染的图像样本提出逐点加权平均与自适应逐点阈值去噪相结合的联合去噪方法,并比较先加权平均(Average)后阈值去噪(Threshold)和先阈值去噪(Threshold)后加权平均(Average)两种不同的方案。仿真实验结果表明:逐点加权平均与自适应逐点阈值去噪相结合的联合去噪方法,对含非均匀噪声的多幅图像拷贝具有良好的去噪效果。     

改进小波阈值在红外热波无损检测中的应用

近二十年来红外热波无损检测技术迅速发展,并在较多领域都得到了普遍应用,但碍于其易受环境影响和工作元件不均匀的特殊性,非制冷红外热像仪原始热波图总存在一定程度的噪声污染,因此对原始热波图进行去噪处理是该技术的关键步骤。传统的改进小波阈值去噪方法局限于对阈值进行自适应分解尺度的改造,使阈值函数平滑连续保真。在噪声方差估计方面没有针对性的方法,而噪声的方差估计是阈值的关键变量,这决定了小波阈值去噪的效果。本文将根据红外图像噪声特性建立混合噪声模型,在噪声模型的基础上进行噪声方差估计、改进阈值及阈值函数,通过软件获取最佳函数参数,最后对仿真模拟结果进行分析,对真实图像进行处理评价,结果表明经改进后的小波阈值去噪方法相对于传统阈值去噪方法和部分滤波去噪方法具有更好的去噪效果。     

一种小波域与空域相结合的图像滤波方法

利用小波阈值去噪方法和传统空间域Lee滤波的特点,提出了一种图像去噪的的组合滤波方案。首先在小波域对图像阈值去噪,得到预去噪图像;再在空间域上利用自适应Wiener滤波器进一步提高恢复图像的精度。为了保证小波域和空间域两种算法之间的匹配,对预去噪图像中残留噪声的分布进行了研究,对其噪声方差估计做了改进,提出了一种估计噪声方差的近似最优公式。仿真实验表明,与单独的在小波域或空域去噪相比,该方法的均方误差和信噪比指标均得到了改善。     

一种小波域与空域相结合的图像滤波方法

利用小波阈值去噪方法和传统空间域Lee 滤波的特点, 提出了一种图像去噪的的组合滤波方案。首先在小波域对图像阈值去噪, 得到预去噪图像; 再在空间域上利用自适应Wiener 滤波器进一步提高恢复图像的精度。为了保证小波域和空间域两种算法之间的匹配, 对预去噪图像中残留噪声的分布进行了研究, 对其噪声方差估计做了改进, 提出了一种估计噪声方差的近似最优公式。仿真实验表明, 与单独的在小波域或空域去噪相比, 该方法的均方误差和信噪比指标均得到了改善。     

基于小波域HMT模型的图像去噪研究

研究小波域隐式马尔可夫模型树(HMT),提出了一种基于小波域HMT模型抑制高斯白噪声的改进图像去噪算法.首先将噪声图像沿水平、垂直及对角方向进行平移变换;然后对平移后的图像进行小波变换,建立其对应的小波域HMT型,分别进行去噪处理.最后取所有去噪图像的均值作为最终的去噪图像.在仿真实验中,对不同程度污染下高斯白噪声的Lena图像分别采用该文算法、小波域硬阈值与软阈值去噪进行比较.结果表明,该文算法很好地保留了图像的细节和边缘信息;提高了图像的峰值信噪比;抑制了Gibbs效应;具有较好的去噪效果.通过实验仿真可以看出,这种方法较好地去除了白噪声;提高了图像的峰值信噪比;较好地保存了图像的边缘和细节信息;抑制了振铃现象.     

非合作水雷目标图像非均匀强噪声去除方法

水雷目标探测会受到水下非均匀强噪声（有机质、悬浮颗粒等）的干扰,为了解决这一问题,提出了一种新的去噪方法。首先优化局部保边缘滤波算法,提出了基于边缘感知约束的局部保边缘滤波,在模型中引入了一个空间自适应的边缘感知约束正则化项,用来更好地表征图像的边缘及细节,使得算法的保边缘平滑特性更好。其次针对强噪声的非均匀特性,采用多尺度策略,迭代地将优化后的模型运用到每个尺度的去噪结果上生成多尺度分解,并在多尺度分解的过程中,逐步增加去噪尺度,将不同尺度的噪声逐步从上一尺度的去噪结果中分离出来。实验结果表明,相较于其他经典去噪方法,提出的算法能够在更好地去除水下非均匀强噪声的同时保留水雷目标信息,对实时水雷作业有着一定的指导意义。     

基于噪声整形的语音去噪算法

针对非平稳环境噪声提出一种基于噪声整形的语音去噪算法.该算法以最小感知均方误差为准则,在Wiener滤波的基础上,采用听觉感知加权函数修正Wiener滤波方程,实现对噪声谱整形,使噪声谱分布特性跟随语音谱而变:同时引入频率补偿因子克服非平稳噪声谱对语音影响的不均匀性;采用快速噪声估计算法实现对非平稳的估计.实验表明,该算法能更有效地抑制背景噪声,提高了去噪后的语音质量.     

基于数据融合的SAR图像斑点噪声抑制

合成孔径雷达图像中的斑点噪声极大地降低了图像的可读性，不利于图像解译和信息提取。根据均值滤波和小波软阈值去噪算法的优点，提出了一种基于数据融合的合成孔径雷达图像相干斑抑制算法。该方法首先对含噪图像进行均值滤波和小波软阈值去噪，再对滤波后的两幅图像在小波域进行数据融合。实验结果表明，这种方法抑制SAR图像斑点噪声的效果较好。     

基于模糊PCNN的小波域超声医学图像去噪方法

在分析了斑点噪声和PCNN的特点的基础上,将PCNN引入到小波域中,并结合小波软阈值去噪思想,提出了基于PCNN的超声医学图像软阈值去噪方法(ST-PCNN),该方法的优点是实现了在小波域中利用PCNN来识别高频信号的小波系数,并采用相应的方法处理小波系数,改善了PCNN难以确定斑点噪声的位置和采用固定阈值造成高频信号损失的缺点,更好的保留了低于固定阈值的高频信号的小波系数;在此基础上,将模糊算法引入到PCNN模型中,进一步提出了基于模糊PCNN的小波域超声医学图像去噪方法(F-PCNN-WD),该方法利用模糊算法来去除PCNN点火过程中大于点火阈值的斑点噪声的小波系数,以更好的去除斑点噪声。实验结果表明,ST-PCNN和F-PCNN-WD方法不仅能够有效地去除噪声,而且能够很好的保留图像的边缘和细节信息。     

基于小波阈值算法的海杂波信号去噪

为有效提取噪声背景下的海杂波信号,针对海杂波信号非线性非平稳的特点,提出基于小波阈值算法对实测海杂波数据去噪。在噪声水平未知条件下,提出基于噪声主要在高频段且能量较小、信号主要集中在低频段思想的噪声判断准则。为验证小波去噪效果,将该算法对含有噪声的海杂波实测数据进行去噪,采用均方差和降噪信号信噪比两项指标来衡量去噪效果,并与均值和中值等去噪方法对比,小波算法在这两项指标均优于其他算法;此外,实验结果还表明,db2小波在双曲线阈值函数和HeurSure阈值模式下优于其他小波去噪效果。     

夹层散斑照相逐点滤波条纹特征分析

本文对夹层散斑照相的逐点滤波条纹的形成进行了理论推导，并就得到的有心二次曲线条纹的特征与散斑位移的关系作了详细的讨论。     

B掺杂ZnO纳米薄膜的结构和光学特性研究

采用脉冲磁控溅射法制备了B掺杂ZnO(ZnO:B)纳米薄膜,并用X射线衍射(XRD)、扫描电子显微镜(SEM)和紫外-可见-近红外分光光度计分别研究了薄膜的结构和光学特性。结果表明:ZnO:B为多晶纳米薄膜,具有六方钎锌矿结构,且薄膜沿着c轴取向择优生长;在可见光和近红外光谱区的透光性能良好,其中在可见光区的平均透光率大于84%,而在近红外区的透光率随着波长增加而逐渐降低至45%。运用逐点无约束最优化法分析计算了薄膜的光学常数,在可见光区,ZnO:B纳米薄膜的光学常数随波长的变化很小且数值基本恒定,折射率约为2.0,而在紫外区,光学常数随波长的变化显著。     

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.