基于ReLU激活函数的轧制力神经网络预报模型

平整机轧制力的预报对轧制过程的优化控制有着重要意义。针对平整机轧制力预测精度不高的问题,提出采用Re LU(Rectified Linear Units)激活函数的神经网络模型来预报平整机的轧制力。在对数据进行主成分分析后,得到影响轧制力的主要因素,并将其作为神经网络的输入层,将平整机轧制力作为输出层,通过使用Python语言编程进行实验,对神经网络模型隐层的相关参数及算法进行单一变量筛选,建立了保证轧制力预报精度最高的神经网络模型。实验结果表明,通过调整隐层层数、神经元数、传播算法、正则化方法,该模型能够将预测误差控制在10%以内,且该实验方法能够对不同输入参数下的平整机轧制力进行精确预报。     

基于支持向量回归的二次冷轧轧制力预报模型

为提高二次冷轧兼平整机组在二次冷轧模式下轧制力的预报精度,建立了一种基于摩擦系数自学习的轧制力预报模型。考虑到摩擦系数自学习模型的不足,为进一步提高轧制力的预报精度,提出了一种支持向量回归预测轧制力的计算误差与摩擦系数自学习相结合的轧制力预报方法。结果表明,该模型的计算值与实际值吻合较好,误差控制在±7%以内,满足现场生产要求,具有较高的工程应用价值。     

基于神经网络和自适应预报模型参数的平整轧制力模型

冷轧带钢平整过程存在带材较薄,压下率较小等特点,应力状况较为复杂,采用传统模型对轧制力预报误差较大。采用神经网络模型对应力状态系数进行预报,可提高轧制力的预报精度。针对轧制过程中轧件特性发生缓慢变化的特点,采用符合平整轧制过程特点的变形抗力自适应模型,并与神经网络模型结合,预报平整轧制力。计算结果表明,该模型计算值与实际值吻合精度较高,90%的预报结果相对误差控制在5%以内。     

热镀锌机组平整机轧制力预设定模型研究

针对现阶段平整机生产中存在的横型计算成功率低、预设定精度差等问题,在分析平整机原有轧制力模型的基础上,采用理论分析与现场实际数据统计相结合的办法,设计出适合平整机预设定机理模型。采用预设定表格和机理模型结合的方法优化设定平整工艺参数,并通过分析大量生产实际数据不断优化单位张力,以及摩擦系数、变形抗力、张力影响因子等模型参数,提高模型的预设定精度,实现减少手动设定,进而提高产品质量的目标。从模型上线跟踪情况可知,预设定模型的精度较高,对实际生产具有很好的指导效果。     

平整机轧制力阶跃奇异点的小波检测与分析

轧制力阶跃奇异点是对平整机轧制力控制系统进行故障诊断和系统分析的一类重要数据,采用小波分析方法对平整机轧制力控制系统阶跃奇异点进行检测、定位和分析.对奇异点检测的小波分析方法进行探讨,确定了用于轧制力阶跃奇异点检测的小波基函数.通过采用小波阶跃奇异点检测方法对某平整机实际轧制力数据进行阶跃奇异点的检测和定位,论证了该方法的正确性.     

攀钢1 220 mm冷连轧机轧制力模型参数自学习分析

在冷连轧过程控制中,影响轧制力模型预报精度的主要因素是材料的屈服应力和摩擦系数。攀钢1 220 mm冷连轧机屈服应力模型通过机架屈服应力自学习、材料等级屈服应力自学习以及材料类别屈服应力补偿来确保屈服应力模型的计算精度。为提高摩擦系数模型的计算精度,除了在模型中充分考虑轧制速度、轧辊粗糙度及轧辊磨损等影响因素外,还引进了低速摩擦系数的自学习形式。另外,攀钢1 220 mm冷连轧机轧制力模型针对特定的轧制条件分别采用调整屈服应力和摩擦系数的自适应学习方法,在实际应用中能够迅速提高轧制力模型的预报精度。     

平整机压下系统稳态性能分析

通过对平整机液压AGC系统的理论分析,对轧制状态下的伺服阀流量、压下油缸调节速度及轧制力等稳态性能参数提出了理论计算方法,该分析方法对平整机液压AGC系统的设计和分析具有指导意义.     

高速线材力能参数预报系统开发

在深入研究各种数学模型的基础上，建立了适合线材轧制的模型，利用VC++和VB联合开发了高速线材力能预报系统。为了提高软件的预报精度，建立了适合高速线材轧制的短时和长时自适应优化模型。在孔型设计时，利用该软件可以提高各机架轧制力、轧制力矩以及轧制功率的预报精度，为校核孔型设计和选择电机提供了指导和参考。通过仿真和软件在现场试用表明，优化后的模型比原模型具有更高的精度，并且在变钢种变规格轧制时误差波动较小。     

宝钢1420平整精度模型研究

通过对宝钢1420冷轧轧制力模型的理论计算和控制方法的分析,认为采用沿高度应力均匀分布的平面假设将带来比较大的误差。对延伸率控制系统的完善和延伸率控制系统的研究,提出了改善该控制系统的设想,将带材的力学性能与外形质量结合来进行调整,经过现场试验与理论研究,通过轧制力设定,既能保证延伸率精度又可以满足板形的要求,在1420冷轧平整机上进行试验,验证了模型的正确性,表明建立的计算模型可提高轧件断面形状和板形的计算精度。     

非稳态条件下平整机延伸率波动分析与控制

针对非稳态下平整机延伸率波动的两个问题,即加速过程中轧制力补偿量偏小,以及启车过程中二级轧制力偏大,分别提出修正速度轧制力前馈模型、增加停车/启车记忆轧制力功能,上述两个方法实施后,非稳态下平整机延伸率波动问题明显改善,延伸率命中率可达到90%以上。     

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).     

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.     

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.     

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。