小波核极限学习机分类器

分析了核极限学习机的原理,提出了一种小波核极限学习机,将小波函数做为极限学习机的核函数,证明了它是一种允许的极限学习机核。通过在双螺旋数据上的测试表明,小波核极限学习机在无训练数据分布的空间也具有分类能力,而高斯核极限学习机在没有训练数据分布的空间不具备分类能力。通过在不同的UCI数据集中的测试得出小波核极限学习机具有较高的分类性能。最后将小波核极限学习机应用到了人脸识别问题上,同样取得了优良的性能,说明小波核极限学习机具有一定的应用价值。     

小波核极限学习机在人脸识别中的应用

文章提出了一种基于小波核极限学习机(Wavelet Kernel Extreme Learning Machine,WK-ELM)的人脸识别算法。首先,使用2D盖博小波变换对人脸图片进行初步的人脸特征提取。为了从所有提取的特征中选择出与人脸识别相关的、必要的特征,使用主成分分析法(Principal Component Analysis,PCA)对经过初步处理后的图像再进行进一步处理,有效地降低了特征维数。然后使用小波核极限学习机对提取到的图像进行分类。实验证明,小波核极限学习机不仅识别性能高,而且训练速度也优于其他算法。     

K插值单纯形法核极限学习机的研究

针对核极限学习机高斯核函数参数选优难,影响学习机训练收敛速度和分类精度的问题,该文提出一种K插值单纯形法的核极限学习机算法。把核极限学习机的训练看作一个无约束优化问题,在训练迭代过程中,用Nelder-Mead单纯形法搜索高斯核函数的最优核参数,提高所提算法的分类精度。引入K插值为Nelder-Mead单纯形法提供合适的初值,减少单纯形法的迭代次数,提高了新算法的训练收敛效率。通过在UCI数据集上的仿真实验并与其它算法比较,新算法具有更快的收敛速度和更高的分类精度。     

二元裂解算子交替方向乘子法的核极限学习机

凸优化形式的核极限学习机(KELM)具有较高的分类准确率,但用迭代法训练凸优化核极限学习机要较传统核极限学习机的解线性方程法花费更长时间。针对此问题,该文提出一种2元裂解算子交替方向乘子法(BSADMM-KELM)来提高凸优化核极限学习机的训练速度。首先引入2元裂解算子,将求核极限学习机最优解的过程分裂为两个中间算子的优化过程,再通过中间算子的迭代计算而得到原问题的最优解。在22个UCI数据集上所提算法的训练时间较有效集法平均快29倍,较内点法平均快4倍,分类精度亦优于传统的核极限学习机;在大规模数据集上该文算法的训练时间优于传统核极限学习机。     

二元裂解算子交替方向乘子法的核极限学习机

凸优化形式的核极限学习机(KELM)具有较高的分类准确率,但用迭代法训练凸优化核极限学习机要较传统核极限学习机的解线性方程法花费更长时间.针对此问题,该文提出一种2元裂解算子交替方向乘子法(BSADMM-KELM)来提高凸优化核极限学习机的训练速度.首先引入2元裂解算子,将求核极限学习机最优解的过程分裂为两个中间算子的优化过程,再通过中间算子的迭代计算而得到原问题的最优解.在22个UCI数据集上所提算法的训练时间较有效集法平均快29倍,较内点法平均快4倍,分类精度亦优于传统的核极限学习机;在大规模数据集上该文算法的训练时间优于传统核极限学习机.     

多尺度特征融合与极限学习机结合的交通标志识别

针对卷积神经网络只能使用相同尺寸图像和卷积核的网络进行特征提取,导致提取的特征不全面,在交通标志识别中因车载摄像头与交通标志的位置不断变化影响交通标志的识别精度等问题,提出了一种基于多尺度特征融合与极限学习机结合的交通标志识别方法。首先,将预训练适应3种不同尺寸图像的网络模型作为实验的初始模型;然后,融合3个网络模型构建多尺度卷积神经网络,将3个预训练网络的参数级联到融合模型的全连接层,对融合模型的全连接层进行训练,采用随机梯度下降算法更新网络参数;最后,将融合后的模型作为特征提取器提取特征,把提取到的多尺度特征送入极限学习机,实现交通标志识别。实验采用德国交通标志数据库(GTSRB)对算法性能进行测试,实验结果显示,多尺度特征融合与极限学习机结合的网络识别精度为99.23%,识别速度为46ms。相对于预训练的网络,网络的分类精度分别提高了2.35%,3.22%,3.74%。多尺度特征融合能够有效提取交通标志图像的特征信息,极限学习机可以提高分类精度和分类时间,该方法能满足交通标志识别的准确性和实时性的要求。     

改进蝙蝠算法优化极限学习机的图像分类

针对分类器中的极限学习机参数优化问题,本文提出一种改进蝙蝠算法优化极限学习机的图像分类模型。首先将极限学习机参数看作蝙蝠位置,然后采用改进蝙蝠算法进行求解。采用病毒群体感染主群体,主群体在历代个体间纵向传递信息,病毒群体通过感染操作在同代个体间横向传递信息,增强了算法跳出局部极小值的能力。最后根据最优参数建立图像分类模型,并对模型的性能进行仿真测试。仿真结果表明,相对于对比模型,本文模型不仅提高了图像分类正确率,而且加快了分类速度,是一种有效的图像分类模型。     

一种基于Dropout约束深度极限学习机的雷达目标分类算法

雷达目标分类在军事和民用领域发挥着重要作用。极限学习机(Extreme Learning Machine, ELM)因其学习速度快、泛化能力强而被广泛应用于分类任务中。然而,由于其浅层结构,ELM无法有效地捕获数据深层抽象信息。虽然许多研究者已经提出了深度极限学习机,它可以用于自动学习目标高级特征表示,但是当训练样本有限时,模型容易陷入过拟合。为解决此问题,该文提出一种基于Dropout约束的深度极限学习机雷达目标分类算法,在雷达测量数据上的实验结果表明所提算法在分类准确率上达到93.37%,相较栈式自动编码器算法和传统深度极限学习机算法分别提高了5.25%和8.16%,验证了算法有效性。      

改进鲸鱼算法优化核极限学习机在水质光谱分析中的应用

为提高水质光谱分析模型的学习速度与预测精度,采用核极限学习机对水质光谱进行建模,并提出一种具有动态惯性权重的改进鲸鱼优化算法对模型进行参数优化。由于极限学习机的输入权值矩阵和偏置是随机生成的,故引入核方法以减小其输出权值矩阵的波动;将鲸鱼优化算法中的惯性权重在非线性递减的基础上引入随机因子,通过动态调整惯性权重以平衡算法的全局搜索能力与局部开发能力。与传统优化模型进行了对比实验,实验结果表明:基于该方法所建模型具有更高的预测精度,而在相同的学习迭代次数下,核极限学习机的运行时间相对于传统算法约下降50%,且改进鲸鱼优化算法能够以更快的收敛速度使模型达到全局最优。     

反对称双正交小波应用于多尺度边缘提取的研究

本文对反对称双正交小波所具有的多尺度边缘提取能力进行了理论分析，提出了一种反对称双正交小波变换域内的多尺度边缘提取算法，并通过实验进行了验证。该结果为在基于小波变换的压缩数据域内利用边缘信息实现图像检索提供了依据。     

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.     

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.     

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.