基于改进ABC的LSSVM氧化还原电位预测研究

针对氧化还原电位对于生物氧化提金预处理过程的控制和优化具有重要作用,提出了一种基于改进的ABC算法优化最小二乘支持向量机的预测方法。该算法是在标准人工蜂群算法的基础上,通过引入欧氏距离,使得在一定邻域内观察蜂采用不同于雇佣蜂的搜索策略。采用改进的ABC算法优化最小二乘支持向量机的参数,取得最优解并赋予最小二乘支持向量机进行预测。以新疆某金矿的生产数据进行仿真研究,结果表明：基于改进的ABC算法优化的最小二乘支持向量机具有较高的预测精度,该方法能使模型取得较好的预测效果。     

混沌的模糊神经网络逆系统控制

提出用Sugeno型的模糊推理神经网络建立混沌系统的逆系统模型,并采用逆系统方法进行混沌的控制.这种方法的特点是可以不必建立混沌系统的解析模型,通过模糊神经网络学习混沌系统的运动规律,通过学习获得的规律对混沌进行有效的控制,并且该控制方法可以控制混沌系统以一定精度跟踪连续变化的给定信号.理论分析及针对虫口模型和Henon模型仿真研究证明了该方法的有效性 关键词： 混沌 模糊神经网络 逆系统控制     

基于最小二乘支持向量机建模的混沌系统控制

提出了基于最小二乘支持向量机（LS-SVMs）建模的混沌系统控制方法.与前向神经网络相比，LS-SVMs的优点是其训练过程遵循结构风险最小化原则，不易发生过拟合现象；它通过解一组线性方程组可得到全局惟一的最优解；LS-SVMs的拓扑结构在训练结束时自动获得而不需要预先确定.该方法不需要被控混沌系统的解析模型，且当测量噪声存在情况下控制仍然有效.以一维和二维非线性映射为例进行数值仿真，表明该方法是有效和可行的. 关键词： 混沌控制 支持向量机 建模     

基于PCA-BP神经网络的光谱消光法颗粒粒径反演算法研究

光谱消光法广泛应用于颗粒粒径测量领域,在利用光谱消光法对颗粒粒径进行反演的过程中,由于颗粒的消光系数存在理论复杂、计算繁琐、收敛速度慢以及求解不稳定等问题,很大程度上影响了整个反演过程的快速性和准确性。且在众多波长的消光数据中,存在较多重复冗余的信息,也很大程度上增加了反演算法的时间。针对光谱消光法粒径反演算法计算繁琐、反演效率低的问题,提出了基于主成分分析（PCA）和BP神经网络的光谱消光颗粒粒径分析方法。基于Mie散射理论对不同粒径、不同波长下的光谱消光值进行了仿真计算,通过对光谱消光数据集的主成分分析及各个波长综合载荷系数的计算,实现了最优特征波长的选取,利用降维后的光谱消光数据训练了PCA-BP神经网络模型,并利用该网络模型计算了粒径颗粒分布。通过仿真计算,比较了PCA-BP神经网络模型与传统的BP神经网络模型的预测精度,并分析了波长数目对两种神经网络模型预测结果的影响。针对训练得到的PCA-BP神经网络模型开展光谱消光法粒径参数反演算法的验证实验,搭建了光谱消光法颗粒粒径参数测量实验系统,测量了粒径范围在0.5～9.7 μm内的6种不同粒径参数的聚苯乙烯标准颗粒。仿真和实验结果表明：基于主成分分析方法可确定各个波长向量之间的相关性,利用综合载荷系数选取最优特征波长对应的消光值对整体的光谱数据具有较好的代表性,可实现光谱数据的降维。相比传统的BP神经网络模型,基于PCA-BP神经网络模型的颗粒粒径分布的分析方法预测精度更高,对于较分散颗粒系的分布参数的预测有更加明显的优势。而且,被选取的波长数较少时,PCA-BP神经网络模型依然有较高的预测精度。利用训练好的PCA-BP神经网络模型对颗粒粒径参数进行实验验证,预测结果可瞬时输出,颗粒粒径分布误差在5%以内,验证了该算法的可行性。     

基于Bernstein多项式的自适应混沌时间序列预测算法

提出了利用Bernstein多项式对混沌时间序列的动力学方程进行建模的方法,并将该方法与递推最小二乘(RLS)算法相结合,从而可以自适应地逼近混沌时间序列的动力学特性,以达到预测的目的.理论分析和仿真实验表明该方法对一些常见的混沌时间序列具有较高的预测精度和较理想的准确预测率.由于RLS算法的收敛速度较快,因此该方法比较适合于对短混沌时间序列进行实时预测. 关键词： 混沌 预测 Bernstein多项式 RLS算法     

基于遗传算法的锂离子电池等效电路参数识别

结合锂离子电池双极性等效电路模型提出了一种基于遗传算法的参数识别方法,该方法通过指数函数对电路模型中的电阻、电容、恒压源等元件进行有理逼近,根据电池在不同充放电速率下的输出电压特性数据,通过实数编码遗传算法得到最优的函数参数,从而得到最优的电阻、电容,开路电压等电路参数值,针对电池在不同的工作状态,不同的工作参数下的运行数据,系列仿真和实验结果表明该算法原理简明,收敛较快,辨识得到的最优模型其电压输出特性与电池的实际电压输出特性基本吻合,能较精确的反映电池的实际特性,具有较高的辨识精度。     

遗传算法和神经网络的重叠光谱解析

随着光谱分析及荧光检测技术的快速发展,单色荧光标记已无法对细胞样本进行精准判断,必须采用双染色或多色荧光标记来分析细胞内部结构。然而,使用光谱测量方法进行多色荧光分析时,由于通常使用多种标记物同时对待测细胞进行标记,发射光谱会产生部分光谱重叠,为了准确对其进行分析,需将重叠峰分解为独立谱峰。针对光谱重叠现象,提出了遗传算法优化BP神经网络(GA_BP)的重叠峰解析算法。首先确定了BP神经网络具体结构,并对重叠峰信号进行二次微分预处理,确定重叠峰中单峰个数及单峰位置,将其作为重叠峰信号的特征值送入BP神经网络的输入层;其次将BP神经网络权值及阈值初始化,利用遗传算法全局搜索的优势,进行算法初始种群及种群规模等最优参数的选取,通过选择、交叉、变异等一系列遗传进化操作进行寻优计算,得到包含BP神经网络最优权值和阈值的个体;然后确定网络最优参数并进行相应网络训练,使优化后的BP神经网络可从输出节点处获得独立单峰的峰宽及强度;最后结合二次微分处理得到的重叠峰特征值,即可分离出单个谱峰。以随机生成的多组高斯重叠峰数学模型作为实验数据进行仿真实验,结果表明该方法具有较高的精确度。其中,双峰重叠峰及三峰重叠峰分解后峰强度及峰宽的最大相对误差分别为0.30%, 3.57%和0.64%, 3.83%;同时也可对四峰重叠峰进行较为准确的分解。此外,将GA_BP网络模型与未经优化的BP神经网络模型作对比,结果表明GA_BP网络运行5步后即可达到预设的误差值,而未经优化的网络模型则需19步方可达到,进一步证明GA_BP网络模型收敛更快且误差较低。由此可见, GA_BP算法在重叠光谱分析中有较好的效果,并可应用于其他能谱重叠峰的分解,与传统方法相比具有明显的优势,具有一定的实用价值。     

铁磁材料磁滞回线的BP神经网络分析方法设计

BP神经网络可以通过调整连接权重按预定精确度逼近非线性函数,利用这一特点可对非线性函数关系进行拟合。文章中利用BP神经网络对铁磁材料磁滞回线实验数据进行了拟合与处理,结果显示该方法处理结果精确度高,拟合效果好。     

基于预测PI的多变量控制在锅炉燃烧系统中的应用

在锅炉的燃烧控制系统中,燃烧对象是一个具有多变量、强耦合、强干扰、大滞后等特性的复杂过程系统,常规的PID控制无法满足实际需求。针对该问题,提出了将动态解耦方法与非线性最小二乘优化算法相结合,得到降阶模型,并运用预测PI控制算法进行控制研究。仿真结果表明：基于降阶模型的预测PI解耦控制策略具有良好的稳定性和鲁棒性,且抗干扰能力强,具有一定的实际应用价值。     

混沌系统的非线性连续预测变结构控制与同步

在连续时间混沌系统的控制与同步问题统一处理的基础上,给出一种可实现两个相同或不同连续时间混沌系统的控制与同步的预测变结构控制方法.其控制器由针对对象标称非线性模型设计的连续预测控制器和针对对象不确定性设计的滑模变结构控制器组成.所提出的方案具有变结构控制鲁棒性强的优点,实现了系统对参考信号的追踪控制.数值仿真表明了本方法的有效性 关键词： 混沌同步 预测控制 滑模 变结构 鲁棒性     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.