基于AMESim和Simulink的汽车电动助力转向系统的联合仿真

以研究电动助力转向系统的助力控制模式的跟踪性能和轻便性为目的,在AMESim和Simulink平台上创建了电动助力转向系统联合仿真模型.仿真结果表明,所设计的PID控制算法使电动助力转向系统具有良好的跟踪性能和轻便性.仿真结果为电动助力转向控制系统的设计提供了依据.     

基于LabVIEW的电动伺服阀加载测控系统

针对传统电磁阀电磁滞后等不足,用某型电动伺服阀取代电磁阀以满足姿轨控发动机的高推力、高精度要求。为对其进行半实物仿真测试,基于伺服旋转电机加滚珠丝杠,设计了电动伺服阀综合性能加载测控系统。硬件采用先进的PXI总线搭建,软件采用Lab VIEW作为上位机平台,具体设计了主程序、实时程序及通信方式;为抑制伺服阀的位置扰动并提高加载精度,提出一种前馈位置补偿和力闭环PID控制的方法。实验结果表明:用该系统有效地测试了电动伺服阀承受外载能力及其输出位移精度,且满足"双十指标"。     

基于CMAC滑模控制的6自由度电动平台仿真分析与耦合实验

以并联6自由度电动平台为研究对象,针对各电动缸之间的强耦合性及外负载扰动的不确定性,提出一种基于小脑神经网络(CMAC)滑模控制策略,充分利用CMAC响应速度快及滑模变结构控制(SMC)抗干扰能力强的特点,以解决传统控制方法鲁棒性差的问题。通过位姿和动力学分析,讨论了影响6自由度电动平台动态特性的关键因素,并以此进行了仿真训练和耦合性实验。结果表明,电动缸的实际位姿能准确跟踪预定轨迹,说明CMAC滑模控制可有效解决电动缸之间的强耦合问题。     

基于PID参数模糊自整定控制的电动助力转向系统跟随性研究

针对汽车电动助力转向系统(EPS)对控制系统的高跟踪性、高协调性要求,在分析PID控制及PID参数变化对系统性能影响的基础上,提出用模糊推理方法在动态过程中改变PID参数模糊自整定控制策略.仿真结果表明,所设计的电动转向控制系统具有良好的跟踪性能,较好地保证了控制量的可靠性和系统的实时性.     

基于LabVIEW和PXI的电动直线加载系统

针对某型航天用电动伺服阀,提出一种基于Lab VIEW和PXI的电动直线加载系统(ELLS)以测试电动伺服阀的实际推力。机械结构上采用大导程精密滚珠丝杠副作为力矩/力转换元件,并采用PXI总线搭建了ELLS的硬件架构,选用Lab Vl EW软件开发了上位机软件平台;为抑制ELLS多余力,提出一种基于电流内环、位置内环和力外环的三闭环复合控制策略,并在电流内环中应用基于复矢量PI控制的电流耦合补偿方法。最后,搭建了ELLS,并进行了信号跟踪实验,结果表明ELLS以较高精度有效地测试了电动伺服阀,所提控制方法有效抑制了多余力。     

直驱H型平台的Laguerre迭代轮廓控制研究

针对直驱H型平台在跟踪大曲率复杂轮廓时,轮廓精度低的问题,提出一种精密轮廓跟踪迭代控制方法.采用有理多项式求根的方法精确计算在大曲率高速运动过程中的轮廓误差精确模型,应用Laguerre迭代估计方法结合交叉耦合控制器设计了综合考虑多轴协同运动的控制方案,以切实保证此类系统在实际应用中的高性能轮廓跟踪.系统实验结果表明,...     

基于Android平台的人脸跟踪系统设计与实现（英文）

针对现阶段大多数Android平台下人脸检测与跟踪系统精度不高的问题,设计了一种基于Android平台的无监督人脸目标检测与跟踪系统来解决这个问题。该系统采用基于粒子滤波和背景减除的方法,能够在无先验知识的情况下自动探测和跟踪视频监控序列中移动人脸目标。采用VC++和Open CV对该方法进行了具体实现,并介绍了开发环境搭建,最后成功移植到Android平台上。实验测试结果表明,该方法可以成功地检测并跟踪人脸目标。与其他方法进行比较,提出的方法的实时性和稳健性能更高,即跟踪效果更好。     

下肢外骨骼机器人设计及实验研究

为实现下肢残障者的运动康复,设计液压驱动的下肢外骨骼机器人机构。针对下肢外骨骼的运动跟随需求,提出一种滑模控制器,并进行了控制仿真模拟。仿真结果表明：外骨骼采用该控制算法能较好地实现位置跟踪。基于dSPACE硬件在环实时仿真系统搭建了下肢外骨骼系统,进行了空摆实验、被动跟随实验及主动跟随实验。实验结果表明：设计的下肢助力外骨骼机器人能够为穿戴者提供助力,外骨骼样机的整体稳定性较好,对穿戴者具有良好的跟踪性能与快速响应性。     

基于Android平台的人脸跟踪系统设计与实现

针对现阶段大多数Android平台下人脸检测与跟踪系统精度不高的问题，设计了一种基于Android平台的无监督人脸目标检测与跟踪系统来解决这个问题。该系统采用基于粒子滤波和背景减除的方法，能够在无先验知识的情况下自动探测和跟踪视频监控序列中移动人脸目标。采用 VC+〖KG-*2〗+和Open CV对该方法进行了具体实现，并介绍了开发环境搭建，最后成功移植到Android平台上。实验测试结果表明，该方法可以成功地检测并跟踪人脸目标。与其他方法进行比较，提出的方法的实时性和稳健性能更高，即跟踪效果更好。     

基于音圈电机X-Y精密定位平台的控制系统设计

针对由音圈电机驱动的X-Y精密定位平台系统,提出了一种基于S函数的实时离散傅里叶变换(DFT)算法来进行系统辨识,从而建立定位平台的数学模型.基于系统数学模型,采用混合灵敏度优化的方法,设计了一种H∞鲁棒控制器.该控制器对模型的不确定性及外部干扰具有较好的抑制作用,从而能够很好地改善系统性能,并利用仿真及实时控制实验验证该控制算法的有效性.结果表明该控制器较好的改善了系统的动态特性,使其具有响应速度快、稳定性好以及良好的抗干扰能力等优点.     

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.