数控机床可用性屋中用户可用性需求分析的合成方法

用户可用性需求获取及权重确定是构建数控机床可用性屋的起点和关键,对于能否真实反映故障因素对可用性需求的最终影响起着重要作用.为有效评估用户可用性需求,提出基于改进AHP与熵权法的主客观赋权法、DEMATEL和Kano模型及数控机床“卖点”的合成分析法.采用AHP与熵权相结合的主客观赋权法确定基本权重;考虑用户可用性需求间相互影响,利用DEMATEL法得到修正权重;兼顾用户可用性需求水平提高率、Kano分类及数控机床“卖点”等市场竞争性评估信息,使所得权重调整因子与修正权重相结合,获取最终合成权重.最后借助实例对该方法的有效性与可行性进行了验证.     

可靠性与维修性耦合的动态可用性研究

可用性是用户评价可修复系统最重要的指标,可靠性与维修性耦合决定了系统的动态可用性水平。以动态可用性为核心,研究可修复系统的故障率(可靠性)、修复率(维修性)的内在联系及其对可用性的影响和相互耦合,建立可修复系统的瞬时可用度模型、稳态可用度模型以及所规定的时间区间内平均可用度模型,从而形成一组可用性的动态模型。结合某系列数控车床可用性分析表明,这种可用性动态分析能够有效地描述不同时间历程可用性的动态变化,对系统的可靠性状况和维修性预测具有重要的指导意义。     

复杂产品可用性屋中故障因素自相关系数确定方法

在复杂产品可用性屋中，精确计算故障因素自相关系数有利于更准确得到故障因素权重，从而更有针对性地构建可用性保障机制。为此本研究给出一种可以综合多名专家意见与多个影响因素的故障因素自相关系数计算方法，将不同专家对故障因素间因果关系的模糊性判断表达为一个可拓区间数，运用可拓层次分析法（Extensional Analytic Hierarchy Process，EAHP)将该可拓区间数转化为确定的值，得到故障因素间的自相关系数。该法全面考虑了故障因素的各种影响因素及其模糊性，使计算获得的故障因素自相关系数准确度更高。最后以某系列复杂产品——加工中心可用性屋的自相关矩阵构建为例，验证了该方法的应用。     

教数控车床刀架系统故障分析

根据采集的21台某型数控车床刀架系统的故障数据,对刀架系统进行故障模式、影响及危害性(FMECA)分析,找出影响该刀架系统可靠性的关键子系统和薄弱环节,明确该型数控车床刀架系统可靠性改进的主攻方向,并有针对性地提出提高刀架系统可靠性的改进措施.     

数控机床可用性屋中用户可用性需求分析的合成方法（英文）

用户可用性需求获取及权重确定是构建数控机床可用性屋的起点和关键,对于能否真实反映故障因素对可用性需求的最终影响起着重要作用。为有效评估用户可用性需求,提出基于改进AHP与熵权法的主客观赋权法、DEMATEL和Kano模型及数控机床"卖点"的合成分析法。采用AHP与熵权相结合的主客观赋权法确定基本权重;考虑用户可用性需求间相互影响,利用DEMATEL法得到修正权重;兼顾用户可用性需求水平提高率、Kano分类及数控机床"卖点"等市场竞争性评估信息,使所得权重调整因子与修正权重相结合,获取最终合成权重。最后借助实例对该方法的有效性与可行性进行了验证。     

车身曲面造型产品质量特性目标规划模型的研究

分析车身曲面造型的用户需求和技术特征,确定用户需求与技术特征之间的相关性和技术特征之间的自相关性,建立车身曲面造型质量屋。对质量屋进行决策时,采用模糊层次分析法确定用户需求权重,通过模糊综合评价法获取用户需求与技术特征之间的相关系数和技术特征之间的自相关系数。根据获得的质量屋参数建立多目标规划模型,使曲面造型质量最大程度的满足用户需求,并优化了曲面产品的造型周期和成本。将该方法应用于某车型前保险杠的曲面造型。     

基于故障分析的数控车床可靠性最优分配研究

结合可靠性现场试验采集的某型号数控车床314个故障数据,确定各个子系统的分布函数和可靠度函数.在给定系统可靠度指标下应用花费最小的可靠度分配方法进行可靠度的最优分配.应用此方法得到可靠性最有增长潜力的子系统和各子系统可靠度的增长情况,为该系列新产品改进提供参考.     

4-RRR冗余并联机构的动力学分析

为了分析冗余4-RRR并联机构在高速、高载荷下的的动力学特性和运动精度,利用坐标变换矩阵求解冗余4-RRR平面并联机构反解方程,推导机构雅克比矩阵。在此基础上,将并联机构分解为动平台和一、二连杆子系统,采用Lagrange法建立子系统动力学模型,然后推导出机构整体动力学模型。以Matalb/Simulink为工具,对该机构的动力学进行算例仿真,仿真结果表明:4-RRR平面并联机构各驱动构件在实现期望轨迹的运动过程中,驱动力和力矩的变化、数值大小各不相同,但均呈正余弦曲线规律变化。所提出的研究方法快速有效,为机构后续研究提供了理论依据。     

一种数控车床故障诊断方法

通过对数控机床可靠性增长技术的研究，利用MTBF值（平均故障间隔时间：Mean Time Between Failures）对国产数控机床进行故障诊断。根据采集的数控车床故障数据，对其进行了可靠性分析，计算出了可靠性评定指标，建立了故障间隔时间分布模型。对数控车床进行了故障模式、影响及危害度（FMECA）分析，剖析了数控车床的故障发生机理，找出了产品的薄弱环节，提出了部件或子系统的可靠性改进建议。     

淬火机床的模块化设计应用研究

针对淬火机床制造企业普遍存在的开发能力薄弱、设计周期长、制造困难、成本高昂等问题,在分析现有模块划分方法的基础上,对淬火机床的模块化设计进行研究。通过基于参数的设计结构矩阵DSM描述淬火机床功能部件之间的关系。以模块的高内聚性、模块间低耦合性为划分原则,利用层次分析法AHP确定相关性指标权重,构建功能部件综合结构相关矩阵。结合层次聚类法,通过MATLAB软件作出谱系聚类图,以获得划分方案,实现淬火机床的快速开发。通过模块化设计,可以缩短淬火机床研发周期,实现大批量生产条件下的个性化生产,快速响应市场和用户的多样化需求,使其适应日益激烈的市场竞争。     

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。     

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.     

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.     

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.     

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality of the slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in mold.This technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, thereby controlling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle and partly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structure and angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower than that without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at the top surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial to the growth of equiaxed crystal and decreased element segregation.