不锈钢离心泵叶轮的激光焊接

离心泵叶轮加工质量的好坏将会对离心泵的性能产生重要的影响,然而空间扭曲形叶轮虽然效率高、性能好,但是难于加工,使用传统焊接方法容易产生形变,焊缝粗糙,内应力大,这大大的影响了离心泵的使用效能。通过将激光焊接技术应用于空间扭曲形离心泵叶轮的制造中,则可以有效的解决这些问题。结合阳江新力工业有限公司在离心泵叶轮制造中的生产实际,分析了激光加工技术的优势及其加工方法,并通过对焊缝宏观形貌和金相组织的分析与焊接接头拉伸性能测试表明激光焊接可以获得成型良好的焊缝,焊缝组织细小,热影响区窄,接头显微组织和力学性能优良,适合叶轮的制造。     

H62 黄铜激光焊接性的研究

研究了激光焊接Ｈ６２黄铜时工艺参数对焊缝成形、内部缺陷及合金成分变化的影响规律。结果表明：激光焊接黄铜时线能量不宜过大，过大的线能量将导致飞溅严重，焊缝凹陷加剧、焊缝α相增多、晶粒粗大和焊缝硬度（强度）显著下降。采用大功率激光和大焊速焊接黄铜时焊缝热裂纹倾向增大。激光焊接线能量为１．３５～１．６５ｋＪ／ｃｍ、焦点位置为０．５～１．５ｍｍ时，可获得３ｍｍ厚黄铜板全熔透、无内部缺陷及锌损失小的焊缝。用夹片和盖片方法进行激光焊接可解决焊缝凹陷的问题。     

YAG激光焊接Be/Al合金的结晶组织分析

采用YAG激光焊接方法，通过控制激光束的能量密度和焊接速度，对铍铝两种几乎完全不相溶的金属进行了焊接并得到了良好的接头组织．焊缝和热影响区的显微组织为典型的铍铝共晶组织．     

光束焦点位置对双相不锈钢光纤激光焊接焊缝成形和组织的影响

通过焊接热模拟方法和现代材料组织分析技术,研究了光束焦点位置对于双相不锈钢2205光纤激光焊接焊缝成形和组织的影响.结果表明,激光焦点位置影响了接头温度场分布,随着激光焦点下移进入工件内,焊缝上部逐渐收窄变短,焊缝内气孔数量显著下降,热影响区尺寸无显著改变.此外,光束焦点位置对双相不锈钢焊缝组织具有影响.正离焦时,焊缝中部的奥氏体含量最高;当离焦量为0mm时,焊缝金属上部、中部和下部的奥氏体分布最为均匀.     

光束焦点位置对双相不锈钢光纤激光#br# 焊接焊缝成形和组织的影响

通过焊接热模拟方法和现代材料组织分析技术，研究了光束焦点位置对于双相不锈钢2205光纤激光焊接焊缝成形和组织的影响.结果表明，激光焦点位置影响了接头温度场分布，随着激光焦点下移进入工件内，焊缝上部逐渐收窄变短，焊缝内气孔数量显著下降，热影响区尺寸无显著改变.此外，光束焦点位置对双相不锈钢焊缝组织具有影响.正离焦时，焊缝中部的奥氏体含量最高；当离焦量为0 mm时，焊缝金属上部、中部和下部的奥氏体分布最为均匀.     

Ca对AZ31镁合金CO_2激光焊接接头组织和性能的影响

采用添加填充材料的CO2激光焊接工艺对AZ31镁合金薄板进行焊接,研究了不同Ca含量对焊缝金属的显微组织和力学性能的影响.结果表明:当激光功率为1 500W,焊接速度为3 m/min时,AZ31镁合金CO2激光焊接的焊缝金属中添加一定量的σCa0.19%元素,可以得到成分相对较均匀、组织细小的焊缝.当填充带材为AZC04(焊缝中Cσa=0.19%)时,焊缝区晶粒相对细小,析出相细小弥散,此时焊接接头的力学性能最优,焊接效率基本可达到100%.     

齿轮激光深熔焊接的研究

本文采用高功率CO_2激光焊接组合齿轮;研究了激光焊缝质量与激光焊接工艺参数的关系;采用金相显微镜和扫描电镜观察分析了齿轮激光焊缝区的微观结构;测量了焊缝区的显微硬度分布.文中对齿轮激光焊缝区的缺陷(如裂纹、气孔等)作了较详细的研究,并对激光焊接试样作了拉伸和弯曲试验.     

铝合金的激光焊接

叙述了在铝合金激光焊接中如何改善熔化性、选择工艺参数、防止热裂纹及气孔等缺陷的措施和方法。铝合金激光焊接焊缝金属微观组织特征及微观偏析不仅与合金本身有关系，而且焊接条件对其有很大影响；铝合金焊缝硬度与合金元素含量、焊接工艺条件之间有着密切关系。     

旋转磁场对激光焊缝金属显微组织的影响

研究了旋转磁场对激光焊304不锈钢、Al-12Si合金焊缝金属显微组织,以及304不锈钢与Al-12Si合金连接缺陷的影响．研究结果表明：旋转磁场能有效地对激光焊熔池中液态304不锈钢、A1：12Si合金进行搅拌,抑制柱状晶的产生,细化焊缝金属晶粒．磁场的旋转速率越高,对液态的电磁搅拌作用越强,焊缝金属的晶粒越细小、Al-12Si合金共晶组织越均匀．旋转磁场能消除304不锈钢与Al-12Si合金激光焊焊缝金属中的缺陷,提高304不锈钢与Al-12Si合金焊接接头的性能．     

脉冲YAG激光焊接原位生成TiB_2/ZL101铝基复合材料

采用脉冲激光技术对原位生成TiB2/ZL101铝基复合材料进行焊接,并分析了脉冲频率对焊缝成形及其微观组织、气孔和TiB2粒子在焊缝中分布的影响.结果表明:脉冲激光焊缝成形较好,焊缝内气孔数量较少,焊接后母材中团簇的TiB2粒子变得细小弥散且比母材分布更均匀;当脉冲频率增至200 Hz时,搅拌作用减弱且焊缝内气孔增多,TiB2粒子的弥散分布也相对减弱,激光穿透深度随着脉冲频率的增加而减小;激光焊接时,焊缝呈现出细小的等轴晶组织,在凝固过程中TiB2粒子被界面前沿推移至晶界处,使得其在焊缝内的硬度增加且分布较均匀,焊接后TiB2粒子未与铝基体发生界面反应而保持了对复合材料的增强效果.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with