径向磁轴承合力系数分析

分别给出了径向磁轴承正常和非正常工作两种情况下最大承载力Fmax合力系数KR的计算公式。对KR的各种影响因素及相应的灵敏度进行了综合分析。通过一个应用实例进行的计算表明：磁极数NP、静态气隙S0和转子偏离理想工作点径向位移x都对KR有重要影响。     

热平衡条件约束的推力磁轴承设计参数优化

本文阐述了一种推力磁轴承热平衡条件约束的设计参数优化的有效算法，约束包括外载荷、热平衡、电磁匹配和几何条件。系统设计变量为磁铁内环外径，外径内径。槽口深度和安匝数，还对系统参数作了灵敏度分析，一个高速透平主轴用推力磁轴承的应用实例表明：影响轴承承载力的主要因素是安匝数，静态气隙和槽口截面积，受热平衡和几何条件的限制，静态气隙和槽口面积的可调整范围较小，而适当增大绕组匝数和控制电流，可以显著提高承载力。     

定子定位槽对径向磁力轴承影响的研究

针对有槽不对称的定子结构，利用有限元法对径向磁力轴承的电磁场进行了仿真与计算，并分析了计算结果。提出了几种结构方面的改进措施，为径向磁力轴承进一步的结构优化设计和控制系统的设计提供了依据。     

阶梯槽织构对水润滑止推轴承静态特性的影响

目的 研究非对称性阶梯槽织构对水润滑止推轴承静态特性的影响。方法 首先建立考虑表面织构、紊流以及JFO空化模型的Reynolds方程,再采用有限差分法求解方程,得到织构化轴承的压力分布以及剪应力;然后对压力以及剪应力沿轴承表面积分,求得轴承的承载力及摩擦力;最后研究不同转速以及结构参数下阶梯槽织构对水润滑止推轴承承载力及摩擦力的影响规律。结果 若阶梯槽织构为前槽深、后槽浅,且当前、后槽槽宽相等时,承载力存在最大值;对于前槽浅、后槽深的织构,当前、后槽槽宽相等时,承载力最小。当前槽槽深小于水膜间隙,后槽槽深约为0.67倍的前槽槽深时,轴承承载力最大;当前槽槽深大于水膜间隙,后槽槽深约为0.33倍的前槽槽深时,轴承承载力最大。当前槽槽深不大于水膜间隙（15 μm）时,存在使摩擦力最小的最佳槽深比;当前槽槽深大于15 μm时,随着前后槽深比从0.33增大至1.68,轴承摩擦力逐渐减小。结论 阶梯槽织构起到了减小水润滑止推轴承摩擦力的效果。将阶梯槽设计为沿水流方向前槽深、后槽浅,且前、后槽槽宽相等,可以得到较大的承载力。合适的阶梯槽表面织构参数能够实现大承载、低摩擦。     

均压槽结构对超高速空气静压轴承性能影响分析北大核心

以超高速空气静压止推轴承为研究对象,建立了圆形、环形、扇形和十字形四种均压槽轴承的CFD仿真模型,采用计算流体力学方法,对比分析了有无均压槽轴承在不同气膜厚度与工作转速下对轴承承载性能(压力分布、承载力、刚度、消耗气体质量流量)、稳定性(最大气流速度与湍流动能)的影响。结果表明,气膜厚度和工作转速对5种轴承的承载性和稳定性影响较大,并得到了其影响规律;其中,环形槽轴承兼顾承载性与稳定性,通过实验验证得到环形槽轴承的最佳工作转速。研究成果可为超高速空气静压轴承的进一步优化提供一定的理论依据。     

轴承预紧力对主轴模态及铣削稳定性影响的研究

采用两阶连续梁模型研究不同主轴结构的轴承预紧力对主轴模态及铣削稳定性的影响。研究结果表明:轴承通过改变主轴低阶模态对铣削稳定性产生影响,前轴承对系统模态及铣削稳定性的影响比后轴承大。同一模态影响下的轴端振幅和铣削稳定性之间有很大的联系,激起主轴最大振幅峰值的模态对铣削稳定性的影响最不利。     

油膜轴承承载性能分析及参数优化

给出了油膜轴承的设计条件，以油膜轴承最大承载能力与良好的工作状态作为目标函数，按承载量最大、发热量最小、摩擦系数最小、轴承长径比最小的分目标函数，根据各分目标函数在总的目标函数中的分量，采用线性加权和的形式构成综合目标函数，对其进行优化，并利用实际设计例子进行了验证，得到满意的效果。同时提出了宽径比系列化的设计思想，可简化设计过程和降低生产成本。     

球面解耦永磁偏置磁轴承设计与分析北大核心

针对磁轴承在偏转时产生干扰力矩和磁路耦合问题,提出一种球面解耦永磁偏置磁轴承。基于麦克斯韦电磁吸力方程和等效磁路法理论分析磁轴承的力解耦和磁路解耦,并利用有限元仿真验证理论分析结果。结果表明:在转子发生0.5°偏转时,球面解耦永磁偏置磁轴承的干扰力矩是柱面永磁偏置磁轴承干扰力矩的1.3%,且在轴承径向隔磁块中间位置,气隙磁密约等于0.01 T,磁通几乎不穿过轴承定转子。球面解耦永磁偏置磁轴承可降低干扰力矩,实现磁路解耦,提高控制力矩精度,可用作磁悬浮飞轮的主动高精度控制。     

圆隙缝动静压轴承分析

本文提出了一种新型动静压滑动轴承－圆隙缝动静压轴承，分析了该轴承的承载能力和刚度，并分析了设计参数对它们的影响，结果表明，该轴承性能优于传统的隙缝式轴承。而且这种承加工方便，很有应用前景。     

四自由度电磁轴承—转子系统的数学模型与仿真

电磁轴承是一种依靠电磁力支承转子的新型无接触轴承,与传统油润滑轴承相比,具有许多优越性。但是在系统分析和建模中包括机械结构和控制系统两部分,使其数学模型复杂。本文针对四自由度电磁轴承-转子系统,讨论了磁轴承-转子运动微分方程和控制系统传递函数,建立磁轴承-转子系统的状态方程,并进行仿真。根据系统的仿真结果,考察转子轴颈的运动轨迹,评估控制算法和优化控制器参数,分析转子在高速旋转下的性能。     

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.     

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.     

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.     

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。     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.