超高压卸压系统建模及控制算法研究

利用先进的数学算法与计算机控制技术对温等静压机压力控制系统进行设计,建立了组合式卸压阀的数学模型。针对温等静压机卸压系统的非线性特性,采用模糊和PID双模控制算法控制压力,并在MATLAB平台上对该控制算法进行了Simulink仿真。数值分析和仿真结果表明:所建立的组合式卸压阀的数学模型准确,所选用的模糊和PID双模控制算法可行、有效。     

超高压卸压系统建模及控制算法研究

利用先进的数学算法与计算机控制技术对温等静压机压力控制系统进行设计,建立了组合式卸压阀的数学模型。针对温等静压机卸压系统的非线性特性,采用模糊和PID双模控制算法控制压力,并在MATLAB平台上对该控制算法进行了Simulink仿真。数值分析和仿真结果表明：所建立的组合式卸压阀的数学模型准确,所选用的模糊和PID双模控制算法可行、有效。     

低压铸造液面加压系统的自适应模糊与积分控制

在分析常规模糊控制、规则自适应模糊控制和积分算法的基础上,对低压铸造液面加压系统进行了仿真试验。仿真结果表明,规则自适应模糊控制具有较好的动态和静态性能,不但具有很好的工艺曲线跟踪性能,而且对过程参数的变化有很强的适应性。加入误差连续量的积分作用时,采用分离算法,可消除稳态误差和防止产生较大的超调。本文所采用的控制规则在线自适应算法和积分分离算法相结合的控制方案为低压铸造液面加压系统的控制提供了一条有效途径。     

基于FPGA的温等静压机升压压力控制系统设计

文章以温等静压机压力控制系统中的比例流量阀为研究对象,设计了一种基于DSP Builder设计,FPGA实现的PID控制器.文中简述了温等静压机压力控制系统的组成原理、分析了数字PID控制算法原理、运用DSP Builder设计了PID控制模块,结合ModelSim对控制模块进行测试仿真,并通过QuartusⅡ完成综合、编译、仿真和硬件测试.仿真测试结果验证了应用FPGA实现PID控制器方法的正确性.     

基于DSP的MIG焊接弧长模糊控制系统研究

基于DSP控制的MIG焊接系统,采用缓降弧焊电源外特性和变速送丝的控制方法以达到保证弧长不变的目的,并将模糊控制引入到变速送丝控制设计中.阐述了利用MATLAB的模糊逻辑工具箱进行模糊控制规则设计,并利用Simulink工具箱中的仿真工具对所设计的控制方法进行仿真.实验研究表明,应用该软件设计的控制方法与传统PID控制相比,可快速、准确地控制焊接弧长的稳定.     

基于自适应PID模糊控制的电液随动系统的仿真研究

对自行设计的电液随动系统进行了自适应PID模糊控制研究,并利用MATLAB的仿真工具对此系统进行了仿真试验,仿真结果表明系统具有很好的控制效果,很适合工程应用.     

伺服控制系统的复合模糊自适应PID控制

以工程中的伺服控制系统为研究对象,提出一种嵌入比例因子的复合模糊自适应PID控制方法,即将比例因子模糊控制与模糊PID控制结合而成的复合模糊控制。首先通过MATLAB/Simulink系统工具对无干扰理想状况下的系统进行仿真与分析,然后进一步模拟真实环境下的系统运行状况,在某一时刻加入干扰信号,并将比例因子模糊控制嵌入模糊PID控制中优化算法,对控制系统不断加以改善与优化。试验结果表明,此方法比传统PID控制更具优势,能有效改善控制系统的响应时间、调节时间以及抗干扰能力,有效提高控制系统的动态性能和鲁棒性。     

基于噪声声强最弱的泵控压机卸压特性研究

针对泵控压机液压系统卸压冲击问题,以0.6MN泵控压机为载体,结合功率键合图进行研究,推导出基于噪声声强最弱的理论卸压曲线。搭建了比例变量径向柱塞泵(RKP)模型,并推导出工作缸模型、包含动态摩擦项的修正型分段集中参数管道模型及其它单元模型;以卸压过程中最大声强值最小为目标,运用拉格朗日中值定理,推导出理论卸压曲线;通过仿真对比卸压过程中理论、指数、线性和正弦卸压曲线下的主缸和卸压管压力曲线,并在0.6MN泵控压机上进行实验研究。研究结果表明:基于键合图理论模型的仿真曲线与实测曲线吻合较好,并且理论卸压曲线具有较好的卸压效果,为减小卸压冲击提供了一种有效的新途径。     

微细电火花深小孔加工在线优化伺服算法研究

为了提高微细电火花加工伺服控制系统的精度、实现对伺服间隙的智能控制,提出了以模糊控制算法为基础,通过自调节算法建立合适的目标值,以实现基于模糊控制的BP神经网络在线优化算法,从而提高伺服控制的准确性。同时,采用下位机实现核心控制算法,保证了伺服控制的稳定性和实时性。通过微细电火花深小孔加工实验证明,采用BP神经网络在线优化算法能提高加工精度和加工效率。     

加工中心悬浮系统基于优化函数二级模糊控制

针对龙门移动式数控机床加工中心中单悬浮系统,文章设计了无量化优化函数和二级模糊控制器,采用优化函数来优化模糊规则表,运用插值算法来获得第二级模糊控制的连续校正量,将第一级模糊控制与第二级模糊控制叠加,构成二级模糊控制器。仿真研究结果表明,应用此控制方案对悬浮横梁进行控制,系统有较强的鲁棒性,横梁能够无摩擦稳定悬浮于给定位置。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.