基于CPSO-BP的刀具寿命预测算法

为了改善刀具寿命预测的精准度,文章在已有的PSO-BP神经网络算法中引入混沌理论,提出了一种基于混沌粒子群算法优化BP神经网络(CPSO-BP神经网络)的刀具寿命预测方法。该方法采用粒子群算法优化网络权值和阈值,通过混沌扰动更新粒子的位置。CPSO-BP神经网络算法既避免了BP神经网络存在的收敛速度慢、易陷入局部最优的缺点,又改善了全局搜索能力,同时,降低了粒子群优化算法造成早熟收敛或停滞的可能性。仿真结果表明:与已有的PSO-BP神经网络算法相比,该文的CPSO-BP神经网络算法用于刀具寿命预测时收敛速度和预测精度均更胜一筹。     

基于MPSO-BP对5A06铝合金薄壁件变形预测

为预测不同铣削参数下的5A06铝合金薄壁件的加工变形,文章基于BP神经网络和粒子群算法提出了一种新的方法,该方法对粒子群算法中的惯性权重和学习因子进行动态调整并提出了新的惯性权值自适应策略,之后对相关参数进行优化形成改进粒子群优化算法,最后用改进后的粒子群算法优化BP神经网络并将优化后的BP神经网络用于5A06铝合金薄壁件加工变形预测。仿真实验结果表明:MPSO-BP相对于PSO-BP和BP有较小的预测误差,现场加工实验结果进一步说明了MPSO-BP具有良好的预测精度。     

基于PSO-BP神经网络的连铸漏钢预报

针对传统BP神经网络在训练过程中存在收敛速度慢、易陷入局部最优解的缺陷,将基于群体智能的全局寻优算法-粒子群优化算法引入到BP神经网络的训练过程,建立了PSO-BP神经网络漏钢预报模型;结合某钢厂连铸现场历史数据,分别对PSO-BP漏钢预报模型和BP网络预报模型进行了训练和测试;结果表明,PSO-BP漏钢预报的收敛速度较传统BP神经网络明显加快,其泛化能力和对漏钢温度特征的识别精度也有了较大提高。     

改进PSO优化模糊RBF神经网络的牵引变压器故障诊断研究

为了快速准确地识别出油浸式牵引变压器的常见故障,结合粒子群算法全局搜索能力强、寻优速度快及模糊神经网络容错能力强、自适应性强的特点,提出了将模糊逻辑、RBF神经网络及粒子群算法有机结合的油浸式牵引变压器故障诊断方法。针对粒子群算法局部搜索能力不足的缺点,改进粒子群的速度更新公式和惯性权重,以此优化模糊神经网络的结构参数,从而构建起基于油中气体分析技术的改进PSO优化模糊神经网络的牵引变压器故障诊断模型。实验及仿真结果表明,与BP神经网络、标准PSO优化模糊神经网络相比,改进PSO优化模糊神经网络的故障辨识准确性更高、泛化能力更强。     

基于混沌PSONN-PID神经网络的热连轧活套系统自适应解耦控制

为改善粒子群优化算法的寻优性能,提出了一种新的算法———混沌粒子群算法。该算法将混沌搜索机制引入到粒子群算法中来增加粒子的多样性,同时采用增加粒子交互性策略及先增后减的惯性权重因子模型来设置惯性权重因子,改善了递减策略中存在的缺陷。将改进后的算法与PID型单神经元相结合,并将其用于热连轧活套解耦控制系统。仿真试验表明：该算法较好地克服了粒子群算法易早熟和陷入局部最优的缺点,为解决活套系统高度张力耦合问题提供了一种新的有效途径。     

基于混沌PSONN-PID神经网络的热连轧活套系统自适应解耦控制（英文）

为改善粒子群优化算法的寻优性能,提出了一种新的算法——混沌粒子群算法。该算法将混沌搜索机制引入到粒子群算法中来增加粒子的多样性,同时采用增加粒子交互性策略及先增后减的惯性权重因子模型来设置惯性权重因子,改善了递减策略中存在的缺陷。将改进后的算法与PID型单神经元相结合,并将其用于热连轧活套解耦控制系统。仿真试验表明:该算法较好地克服了粒子群算法易早熟和陷入局部最优的缺点,为解决活套系统高度张力耦合问题提供了一种新的有效途径。     

基于混沌粒子群算法的钛合金薄壁筋铣削变形优化

针对薄壁筋受铣削力影响易变形的问题,提出一种基于薄壳划分和周期性施加铣削负载的变形仿真方法,通过仿真和试验两方面对比研究,分析了薄壁筋的变形过程并得出其变形规律。为了解决标准粒子群算法在优化铣削参数时容易陷入局部最优解的问题,提出一种基于变异算子与自适应动态惯性权重的改进混沌粒子群算法,并以变形量为约束,铣削力最小为目标优化了铣削参数。结果表明:改进后的混沌粒子算法在全局搜索能力和计算速度方面相比粒子群算法显著提高,试验证明采用优化后的铣削参数组合可有效减小薄壁筋的变形。     

基于神经网络的铣削大理石表面粗糙度预测模型

目的利用粒子群优化BP神经网络建立大理石加工表面粗糙度精确预测模型。方法首先采用不同切削参数进行铣削大理石试验,测量加工表面粗糙度值,同时对粒子群算法进行改进,使惯性权重按指数形式递减,并增加速度扰动系数,利用改进粒子群算法优化BP神经网络,建立铣削大理石表面粗糙度神经网络预测模型。其次使用部分试验数据来训练预测模型,使得到的网络参数让网络可以精确预测表面粗糙度。最后利用其余试验数据验证神经网络预测模型的准确性与可靠性。结果经过计算得到粒子群优化BP网络算法的预测模型归一化均方差为0.0501,最大相对误差为10.78%,且误差变化较为均匀。经验公式模型归一化均方差为0.1069,最大相对误差为39.64%,误差变化幅度较大。结论将神经网络模型与经验公式相比较,结果表明,所建网络模型具有较高的预测精度与较强的鲁棒性,对合理选择切削用量以得到理想表面粗糙度有一定参考价值。     

基于改进PSO优化模糊神经网络的数控机床故障诊断技术研究

数控机床故障具有隐蔽性和复杂性的特点,为了快速准确地识别数控机床发生的故障,结合粒子群算法全局搜索能力强、寻优速度快及模糊神经网络容错能力强、自适应性强的特点,提出了将模糊逻辑、RBF神经网络及粒子群算法有机结合的数控机床故障诊断方法。为了改善粒子群算法局部搜索能力,在标准粒子群算法的基础上,改进粒子群的速度更新公式和惯性权重,以此优化模糊神经网络结构参数,从而建立起改进PSO优化模糊神经网络的数控机床主轴伺服系统故障诊断模型。实验和仿真结果表明:与RBF神经网络、标准PSO优化模糊神经网络相比,改进PSO优化模糊神经网络的故障辨识准确性更高、泛化能力更强。     

基于DPSO-BP神经网络的V形自由折弯成形角度和回弹预测北大核心CSCD

采用基于DPSO算法优化BP神经网络(DPSO-BP)的机器学习算法建模,提出一种考虑材料参数和几何参数的V形自由折弯成形角度和回弹的预测方法。该方法主要引入非线性惯性权重改进粒子群(PSO)算法,进一步优化神经网络的初始权值和阈值,构建神经网络预测模型。以不同批号的SUS304不锈钢板料为研究对象,通过设计正交试验得到45个训练样本数据,验证所建立的预测模型的准确性。结果表明:采用DPSO-BP神经网络模型预测的成形角和回弹角的平均误差分别为0.150°和0.120°,与未优化的PSO-BP神经网络模型相比,预测的成形角和回弹角的平均误差明显减小,且计算耗时由14.0 min大幅缩短至0.8 min,同时实现了高预测精度和高计算效率。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。