一种超高层建筑施工整体顶升平台的液压系统设计

超高层建筑的施工是以核心筒为主体进行的,顶升钢平台模架体系在核心筒施工中得到广泛应用。顶升钢平台模架体系的动力系统为多个大功率、长行程液压缸组成的同步控制系统,通过对顶升钢平台模架体系的工况分析,设计一种能满足载荷和其他工况要求的液压系统。设计计算和系统分析结果表明:该同步顶升液压系统性能稳定,可靠性高,安全性高。     

大型结构物多点同步顶升称重控制技术研究

介绍了一套基于PLC的大型结构物同步顶升自动称重系统.该系统通过多个液压缸同步顶升,位移传感器在顶升过程中进行多点同步协调控制,测定各液压缸压力以实现对大型结构物质量及其分布的测量.该系统以PLC为核心,基于现场总线技术,对压力传感器、位移传感器、状态设定系统、液压系统等进行网络监控.通过对各支撑点采集数据的处理确定大型结构物的质量及其重心.该系统已在多个油气田工程的建造中得到成功应用.     

飞机蒙皮拉形机模具快速更换系统设计

针对飞机蒙皮拉形生产中模具更换耗时久、自动化程度低以及拉形设备频繁停机等待等缺点,设计了一种基于"双工位"思想的模具快速更换系统。该模具快速更换系统将模具更换工作移至准备区内进行,在模具更换期间可以同步进行其他批次蒙皮零件的拉形工作。该系统具有结构简单、模具更换快捷、自动化程度高等优点,显著提高了蒙皮拉形生产的工作效率。针对移动工作台顶升过程中存在的偏载问题,设计了一种基于PWM控制的液压同步顶升系统。利用AMESim软件建立了液压同步顶升系统的仿真模型,仿真结果表明,该液压同步顶升系统的同步控制精度高于预期设计目标,满足了移动工作台顶升过程中的位移同步控制要求。     

基于自抗扰的飞机改装液压同步顶升系统研究

在飞机改装作业前需要通过多个千斤顶将飞机进行顶升。由于人工操作和千斤顶的液压缸中元件安装精度等会导致顶升过程中两侧位置不同步。针对飞机同步顶升过程的同步性及稳定性等问题,基于千斤顶中液压缸电液比例阀的数学模型,采用自抗扰同步控制策略,搭建双液压缸电液比例“主从”控制系统仿真模型进行研究。将“主从”自抗扰模型的仿真结果与传统PID控制仿真结果进行比较,结果表明：采用自抗扰控制器可有效减少主从双缸同步误差,实现对工况中扰动的补偿,提高顶升系统精度及抗扰能力。     

顶升台架液压系统异常故障的分析及处理

本文针对某炼钢厂RH真空处理顶升台架液压系统使用中出现的一个异常故障，运用故障树分析方法确定液压故障产生的原因并予以排除，使系统正常运行．     

315 MN压板机液压系统设计

介绍压板机液压系统工作原理。利用分流阀解决动板上升下降过程中的同步问题;利用溢流阀消除液压缸每个行程的同步误差;利用蓄能器和压力开关实现长时间保压过程系统不发热;利用充液阀极大地降低了柱塞泵排量和电机功率。     

液压同步系统在升降桥中的应用

海港为乘客和车辆上下船而设置的升降桥是一种能随潮水的涨落而涨落的可以人工控制其高度的桥。该桥的平稳升降是完全由液压系统控制的。在液压系统中 ,同步阀的应用为控制油缸同步起到了决定性的作用。2　同步的调节在升降桥中 ,要求双油缸上升下降平稳 ,实质上是利用液压系统当中油缸的同步来实现的 ,而调节油缸同步的方法很多 ,大至有以下几种 :图 1　单向节流阀调整　　图 2　单向调速阀调整图 3　同步阀调整1)单向节流阀的调整如图 1,为液压缸单侧回油同步节流回路。在各液压缸的的回油路上装单向节流阀 ,调节节流阀的流量以达到近似的…     

六面顶压机液压系统同步仿真研究

针对传统六面顶压机液压系统的缺陷,提出新的电液比例控制方案,并采用基于PID的位移反馈控制策略以解决其加压同步问题.应用AMESim与Simulink平台进行联合仿真,仿真结果表明,应用PID反馈控制的新型六面顶液压机在加载同步方面能取得比较令人满意的效果.     

多流液压同步马达应用研究

液压同步马达广泛应用于液压系统的同步控制中,其控制精度比其他调速方式高得多.在介绍液压同步马达的结构分类和特点的基础上,以某公司圆方坯连铸机翻转冷床液压系统的12流同步马达为对象,介绍其同步功能的具体实现和影响液压同步马达精度的主要因素及相应的解决方法.     

模糊—PID控制的比例补偿同步系统的设计和试验

本文提出了一种采用模糊-PID复合控制的电液比例补偿同步系统,分析了系统的组成和补偿原理,介绍了模糊-PID控制器的设计。试验证明,该系统具有较高的同步精度和鲁棒性。     

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.     

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。     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.     

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.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.