基于THDMOPSO绿色减速器模块划分不确定优化

针对含不确定的变量或参数的多目标问题,以减速器的模块化绿色配置设计为例,引入区间数和模糊数作为变量,研究了绿色设计中包含不确定因素的产品模块划分问题,给出了模块划分的原则和主要步骤,以模块内部聚合度最大、模块之间耦合度最小和模块划分所得绿色度最高为多目标函数,建立了产品绿色模块划分的不确定优化模型,对其中区间数和三角模糊数确定化后,提出THDMOPSO方法进行求解,通过减速器结构模块构造进行验证,表明此方法具有可行性和生产实用价值。     

不确定环境下虚拟企业生产计划多目标优化模型研究

针对不确定环境下的虚拟企业生产计划的特点,建立了其详细的多目标优化数学模型.当模型中的模糊变量是梯形模糊数时,可利用可行性规划理论将模糊模型转化为清晰等价式,并采用改进的NSGA-Ⅱ算法给出了求解模型的具体步骤,最后通过一个数值算例验证了算法的有效性.     

基于目标驱动优化技术的自冲铆接机C型框架结构优化

通过确定自冲铆接机C型框架优化设计的目标函数和约束条件,提出一种基于目标驱动优化技术的C型框架结构优化方法。首先,建立C型框架有限元模型,以C型框架极限工况为条件进行静力学分析。其次,确定C型框架的载荷和边界条件,以等效应力和总变形量为约束条件,以质量最小化为目标对C型框架进行拓扑优化设计。最后,基于拓扑优化结果提出C型框架形状优化模型,利用中心复合试验法和哈默斯利抽样技术,进行权衡排序,获得较优的初始种群,并且通过决策支持流程得到3组候选样本点,从中确定最优解。数值优化结果表明:C型框架质量减轻了16%,其静强度得到明显改善,说明本文提出的优化方法是有效的。     

基于混沌粒子群的铝热连轧多目标轧制规程优化

针对铝热连轧轧制规程制定过程中的多目标问题,提出一种基于混沌粒子群算法的多目标轧制规程优化方法。选取预防打滑和等功率裕度为多目标优化函数;为了提高粒子群算法的收敛性和分布性,提出一种基于混沌序列的动态加权法选择全局最优粒子,并改进了拥挤距离计算方法;提出一种基于模糊偏好的选择策略用以从最优解集中选择最终采用的轧制规程。基于该方法对某铝热连精轧机组轧制规程进行了优化,验证了该方法的有效性。     

库存容量有限的多产品模糊EPQ模型

当库存容量有限时,传统的经济生产批量模型就不再适用.在以往研究的基础上,考虑库存容量的约束问题,构建了模糊环境下库存容量有限的多产品生产批量模型.该模型允许缺货,存在缺陷品,且缺陷品返工再生产后存在部分废品.利用三角模糊数描述模糊变量,利用符号距离法将模糊模型转化为确定型模型,进而得到最优生产策略,并分析了模糊模型与经典的生产批量模型的关系.最后利用具体算例进行了验证.     

立体视觉测量中的摄像机优化布局

通过合理布置摄像机的安装方位,可迸一步提高立体视觉测量系统的测量精度.将遗传算法应用于求解摄像机优化布局的问题,以摄像机安装方位参数为优化变量,并将摄像机优化布局的目标确定为:寻求最佳的摄像机安装方位参数,使空间点目标的三维重构不确定度最小.采用三维重构不确定度两阶估计方法,即同时考虑摄像机标定和空间点目标三维重构过程中的不确定度传递问题.在Matlab环境下,利用GATBX遗传算法工具箱对该方法进行验证.仿真实验结果表明:经过50代遗传迭代后,可得到优化变量的最优解.     

基于三角模糊TOPSIS算法的制造资源优化选择

网络环境中对制造资源信息的描述往往是不确定的和模糊的。采用最小值区间、最可能值和最大值区间表示的三角模糊数对制造资源信息进行统一描述,探讨了三角模糊数的运算法则、制造资源信息到三角模糊数的转化以及任务需求已知时制造资源信息的修正,引入了目前在决策支持过程中比较流行的TOPSIS算法,研究了基于三角模糊区间的TOPSIS算法以及应用该算法进行制造资源优化选择的一般流程。最后通过实例与已有算法进行比较,验证了该算法的有效性。     

基于遗传算法的箱型结构焊接顺序优化

基于遗传算法原理,建立了箱型结构热-机耦合非线性三维优化仿真模型,以焊接变形为目标函数,进行了焊接顺序数值仿真优化.通过仿真计算优化结果与试验数据比较,证明所提出的优化方法与热-机模型结合是可行的,对于给定的焊接条件,通过选择合适的目标函数,采用遗传算法可以确定最优焊接顺序.这为针对工程具体问题设计焊接工艺提供了可靠的依据.     

考虑EoL产品重用的产品配置优化研究

针对多生命周期产品配置优化问题,将产品组件分为重用组件和新制造组件,对于重用组件,考虑包括再制造在内的一系列EoL产品重用策略;对于新制造组件,则在原始组件的基础上将改进组件考虑在内。通过对需求周期内采用各变体组件比例的研究,以产品配置成本、碳排放量和产品可靠度为优化目标,建立了多目标优化模型,采用gamultiobj函数的遗传算法对该模型进行求解,并基于模糊集理论的Pareto优选机制,得到产品的最优产品配置方案。最后,以某型号汽车发动机为例验证了模型的可行性与合理性。     

板料冲压成形工艺参数多目标模糊优化

将模糊优化理论和有限元分析技术应用到金属板料成形中.利用权重法和隶属函数,在综合考虑了目标函数与约束条件的重要程度后,建立了多目标板料弯曲成形模糊优化数学模型.然后把多目标优化问题转换成为一个单目标优化问题.优化的步骤包括样品生产的正交试验设计、响应面模型接合、精确求解的有限元分析程序.然后使用遗传算法寻求优化求解.实例证明,该方法比传统的有限元分析方法更可行和有效.     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.