热煨弯管用钢板(L360-WG系列)工艺研究

在统计分析、正交多项式回归和模拟试验的基础上,建立了高精度的屈强比预报模型,并运用多元函数极值原理,求导极值点及相应的工艺参数,为优化工艺制度,提高热煨弯管用钢性能合格率提供了定量依据。     

椭-圆孔型连轧大圆钢三维热力耦合弹塑性有限元分析

采用MSC．Marc三维大变形热力耦合弹塑性有限元软件和接触分析技术，对Φ230mm大圆钢两机架热连轧过程中轧件三维变形进行了有限元仿真，计算了轧件主要力能参数的分布值和极值，以此对轧辊强度、孔型尺寸及相关的轧制工艺参数进行分析，得出采用道次小变形量和快速轧制工艺，有助于减缓热作模具钢轧后端部表面残余应力升高和温度降低，避免表面裂纹的产生。     

稀土多组份分馏萃取混合萃取比极值的计算——等效双组份法

本文提出了一种多组份分馏萃取混合萃取比极值的计算方法。文中分析了混合萃取比极值条件下组份在萃取段、洗涤段内的无限区域内恒纯分布的特点,导出了全分布组份A、B在萃取段、洗涤段无限恒纯区内混合萃取比E_(A B)~#、E_(A B)′~#与混合萃取比极值(E_M)_(min)的关系;用等同于双组份体系中β_(A/B)·E_(A B)~*≈E_(A B)′~*,数值关系计算了(E_M)_(min);举例说明了该方法在稀土多组份萃取分离工艺研究中的应用。     

影响16Mnq时效因素的分析

本文从成分、工艺等主要参数入手,根据生产试验数据,运用多元正交回归,求出了时效方程,并且利用多元函数的偏导,得到了极值条件,为在生产中避开时效冲击的极低值点、提高合格率提供了参考依据.     

稀土LF2_(21)电解着色膜物理化学性能的研究

本文叙述了阳极氧化工艺对稀土铝锰合金电解着色膜物理化学性能的影响。结果证实,在硫酸、硫酸亚锡电解着色液中获得的电析着色膜,具有较好的物理、化学性能。稀土含量在0.30%时呈现极值,性能最佳。     

基于有限单元法的罩式退火炉内钢卷温度场分析

采用有限元软件,结合某厂的罩式退火炉工艺特点,对罩式退火炉加热阶段、均热阶段和冷却阶段进行了非稳态的数值模拟。仿真模拟与现场实测温度对比结果表明,仿真精度满足要求。同时进一步分析了罩式炉内各钢卷的温度分布规律,找出了罩退炉中的温度极值区域,并根据生产需要对罩退保温时间进行了优化,得到了更合理的罩退炉工艺。     

CaO—MgOsat—FeOn—SiO2渣系与铁液间磷平衡分配比的极值模型探讨

本文基于实验结果和生产实践,借助多元逐步回归分析等方法,得出了不同碱度区域内反映的Lp极值模型:揭示了Lp与(ΣFeo)或(TFe)之间的极值关系存在下述规律:(1)有一个与Lp最大值对应存在的极值特征准数和(ΣFeO)最佳值;(2)定义该特征准数的变量应根据渣系的特征而定,如本渣系取[(％CaO)+0.7(％MgO)]/(％TFe),CFS渣系取(％CaO)/(％TFe);(3)其特征准数值随渣系或碱度范围不同而不同,在一定的碱度范围内则为定值,并在 Cao/ SiO_2=0.9～1.9,[(％CaO)+0.7(％MgO)/(％TFe)准数值最大,以及在CaO/SiO_2=0.91～1.4范围,(ΣFeO)最佳值最小.可以期望本文提出的Lp极大值模型和极值特征准数对优化炼钢的脱磷工艺具有重要的理论和经济意义。     

轻质氧化镁制备新工艺条件优化

以小化肥厂碳酸化母液和硫酰镁为原料，进行沉淀反应，制备高纯度的轻质氧化镁。应用均匀设计法考察了Ｖ１／Ｖ２（滴定碳化母液至第一等当点和第二等当点时所消耗盐酸的体积比）、沉淀剂用量、反应温度、反应时间、陈化温度及时间对产率的影响。通过回归分析得到回归方程，此方程求极值得到最佳工艺条件。在最佳条件下的实验结果表明：碱式碳酸镁的产率可达９５．５％，轻质氧化镁的纯度达９９．５％以上。     

空拔管壁厚计算模型

采用极值原理的功能平衡法，建立了空拔管壁厚的计算模型，结果表明，计算值与实验值吻合较好，表明该计算模型可以在工程实践中应用。     

极值法确定油缸参数

介绍了用极值法确定所选油缸参数的原理。该法既能满足系统要求，又不会使所选油缸参数过大，并且也避免较繁琐的力学计算。     

复吹转炉水模分散相粒度分布的研究

通过二维水模型模拟复吹转炉吹炼过程。利用数码相机进行摄影,通过对得到图像中分散相的提取与粒度的计算,研究了复吹过程中炉渣与钢液分散相粒度分布的变化。结果表明：复吹转炉存在于连续相中的一定大小分散相出现的频率与其尺寸成一定的比例关系;钢滴分散相的粒度分布随顶吹和底吹强度的增加出现极值;在软吹条件下,渣滴分散相的粒度分布主要受到底吹强度QB的影响,顶吹流量QT几乎对其无影响,在硬吹条件下则受到顶、底吹共同作用的影响。并给出复吹边界条件对分散相的出现频率与其尺寸比例关系影响的经验公式。     

基于混合策略的转炉终点锰含量预测研究

摘要：转炉终点钢水锰含量预测,对原料添加和冶炼成本节约具有重要作用。针对凭经验预估的终点锰含量值与实际值较大偏差导致的生产成本升高的问题,建立了一种基于混合策略的改进型鲸鱼优化算法(IWOA)与最小二乘向量机(LSSVM)的转炉终点锰含量预测模型,引入柯西变异提高鲸鱼优化算法(WOA)跳出局部最优的能力;借助惯性权重增强鲸鱼算法局部搜索能力和收敛精度;提出差分变异以增加鲸鱼算法在探索末期的物种多样性和降低陷入局部最优概率。实验结果表明,IWOA LSSVM锰含量预测模型不仅在全局和局部寻优以及收敛速度有较大的提升,在误差性能指标方面优势明显,且预测误差于±0.01%间的命中率为93.3%。     

改进人工鱼群算法及其在时滞系统辨识中的应用

针对人工鱼群算法(AFSA)存在收敛速度慢和寻优精度低等问题,本文提出了一种改进人工鱼群算法(IAFSA).该算法中的人工鱼能够根据鱼群当前状态调整自身的视野和步长来平衡局部搜索和全局搜索.此外,算法中还加入了引导行为,即人工鱼在觅食行为未发现更优的位置时,当前人工鱼向最优人工鱼移动一步.仿真结果表明,改进人工鱼群算法在收敛速度、寻优精度和克服局部极值等方面有很大优势.本文将改进鱼群算法应用时滞系统的辨识中,辨识结果表明改进算法能获取被控对象的精准数学模型,并具有较强的抗干扰能力.      

Epidemiology abuse: epidemiologic and Psychosocial perspectives on heroin maintenance

The contractility of myocardial strips from the atrium and ventricle of rabbit heart had some differences in the parameters of single contraction, interval--tension relationship, and transitional process. These differences were eliminated by increasing the concentration of epinephrine in bath solution. Epinephrine changed the mode of time--force relation of contraction and induced appearance of extremum in all the parts of the heart. The linear relation between the force of atrium contraction and that of ventricle contraction (homochromity) during change of contraction frequency in normal solution, was shown. The homochromity of atrium and ventricle was broken by high epinphrine concentrations. The level of endogenous catecholamines which modulate the excitation--contraction relations, is believed to determine the differences in the physiological reactions of atrial and ventricular strips. The use of atrium of the heart as a transducer for management of artificial heart is proposed.     

高炉经济煤比和最大喷煤效益计算

结合国内高炉生产实例和数学极值理论,提出了高炉经济煤比和最大喷煤效益的计算方法。     

Effect of growth conditions on the structure of directionally solidified γlγ’δ eutectic

γ/γ/’-δ eutectic alloy containing 21.5 wt pct Nb, 2.5 wt pct Al, balance Ni was directionally solidified under a thermal gradient (G) of 500 K/cm and different schedules of growth rate (R). Under steady state growth rate conditions, the critical (G/R) for plane front solidification is 25 K h/cm². At progressively lower (G/R) the structure becomes richer in γ-phase,i.e. hypoeutectic. Sudden increase in growth speed causes the structure to change from lamellar to cellular and gradual increase in growth speed results in interlamellar spacings that are larger than the extremum values. Sudden decrease in growth speed causes little disturbance in the structure but causes the eutectic grain size to increase.     

Eutectic spacing selection in lead-based alloy systems

Directional solidification studies have been carried out in Pb-Au, Pb-Pd, Pd-Cd, and Pb-Sn systems to characterize the variation in eutectic spacing with velocity. In the Pb-Cd, Pb-Sn, and Pb-Pd systems, statistical distributions of spacings at each velocity were determined and a significant spread was observed. The smallest and the largest spacings, along with the average spacing, have been characterized. A broad distribution curve has been observed for low velocities which becomes sharper as the velocities increase. A comparison with the theoretical model shows that the average spacings are consistently larger than the spacings predicted by the minimum undercooling criterion, whereas the smallest observed spacing corresponds to the theoretical extremum value. Dynamical studies have been carried out to examine the spacing selection process at a given velocity by initially starting with a higher or a lower average spacing. The final spacing distribution at a given velocity was found to be the same irrespective of the initial starting condition which establishes that a definite distribution of spacings exists in eutectic systems without any hysteresis effect and that dynamical effects are not responsible for the existence of a band of stable spacing.     

运用神经网络预报烧结终点

针对现场烧结终点控制复杂与难度大的实际,开发了神经网路预报系统。预报系统采用4层前向神经网络,进行多因素输入建模,输出采用具有极值特性的二次曲线计算的烧结终点与实际最高废气温度,预报烧结终点与最高废气温度,为现场终点控制的最新可行方法。网络结构设计先进合理、精度高、泛化能力强,训练方差为0000 018 14,用训练样本集测试输出,烧结终点绝对平均误差为0.04,终点废气温度绝对平均误差为4.57 ℃。采用训练后网络预报,烧结终点（风箱号）绝对误差最大仅为0.09,终点废气温度绝对误差最大为3.57 ℃,命中率100％。用预报结果有针对性调节烧结参数可收到明显效果。     

The coarsening of lamellae in Ti48Al2Mn2Nb

The thermal stability of as-cast Ti48Al2Mn2Nb alloys has been investigated as a function of time at temperatures of 1200, 1350 and 1420°C. The resultant structures have been characterised using optical microscopy, electron probe microanalysis and transmission electron microscopy. The as-cast structure consists mainly of lamellae of α₂ and γ. Annealing at 1350 and at 1420°C resulted in the continuous and discontinuous coarsening of the primary lamellae. Discontinuous coarsening, which often originates at the sample surface, results in branched irregular secondary lamellae. The average interlamellar spacing of the secondary lamellae is up to a thousand times larger than the primary interlamellar spacing. The extremum principles of maximum velocity and maximum rate of entropy production, used to predict the secondary interlamellar spacing, are inconsistent with the experimental observations. The theoretical predictions of the velocity of the discontinuous coarsening by Livingston and Cahn are used to estimate the value of grain boundary diffusivity at 1350°C. The temperature dependence of discontinuous coarsening is weak, in contrast to the strong effect of lamellar orientation on the rate of discontinuous coarsening.     

Interparticle spacings and undercoolings in Al-Si eutectic microstructures

Modified methods for the measurement of interparticle spacing and undercooling of the Al-Si eutectic have been applied in an attempt to test the applicability to this system of the accepted equation for diffusion-controlled normal eutectic growth. Good agreement with some published measurements has been obtained. For the unmodified and chill-modified eutectic microstructures it seems probable that the basic equation is applicable but that the extremum condition is not. For the impurity modified eutectic there is no agreement with the theoretical prediction, although the possibility is advanced of adding an undercooling term based on twin boundary energy.