预应力旋喷搅拌锚桩在基坑支护工程中的应用

从钻进成孔搅拌、提钻杆复喷、张拉锚索3个层面,描述了某基坑支护工程预应力旋喷搅拌锚桩技术,并通过基坑坡顶水平位移和坡顶沉降监测,结果说明,自钻式预应力旋喷搅拌锚桩加冲钻孔灌注围护桩的基坑支护形式,具有基坑开挖施工便捷、基坑边位移小和总体造价低等优点,在周边场地允许的情况下,对于大跨度深基坑支护有很好的适用性和经济性。     

射流曝气微细气泡的PIV测量

射流曝气产生的微细气泡是影响氧传质效率的关键。在射流曝气传质学原理的基础上,通过搭建PIV实验台对设计加工的射流曝气器产生的微细气泡直径等参量进行测量。结果表明,其产生的微细气泡粒径小、分布均匀,气泡上浮平均速度小,横向平均速度大、有漩涡。这些特点均有助延长气泡滞留时间或加强扰动,提高氧传质的效果。     

射流夹带流速度及夹带量的分析

分析了射流夹带流的特性,建立了柱坐标系及控制体,并利用流体的连续性方程给出了夹带流沿母线的速度公式,同时给出了夹带流流量的理论解,并用数值模拟的方法比较分析了理论解和实验数据,结果表明两者具有良好的一致性.     

Characterisation of a thiosulphate-sulphite gold electrodeposition process

Electrodeposition of soft gold is an important process in the fabrication of micro devices for electronics, optics etc. Traditional gold electroplating is based on a gold cyanide process which is not applicable for the stringent requirements in state of the art micro device manufacture. Newcastle University has been involved in the development of an industrial process based on a mixed ligand electrolyte—the gold thiosulphate-sulphite system. Here we present methods for the formulation of this electrolyte in the laboratory which ensure bath stability and process compatibility. In addition, we have carried out spectrophotometry to elucidate the possible reasons of its chemical stability. Standard rotating disk and cyclic voltammetry has been carried out to determine the electrochemical behaviour of the gold thiosulphate-sulphite system. The changes in electrochemical behaviour as the bath ages are also discussed.     

Multidroplet Impact Model for Prediction of Residual Stresses in Water Jet Peening of Materials

In this article, a multidroplet impact model, proposed for predicting residual stresses induced on materials subjected to water jet peening, is presented. This approach considers the impact pressure distribution due to high-velocity droplets impinging on the material surface instead of stationary pressure distribution for prediction of residual stresses on water jet-peened surfaces. It makes use of Reichardt's theory for predicting the velocity distribution of droplets and liquid impact theory for predicting the impact pressure and duration of impact of high-velocity droplets. For predicting residual stresses on the surface and subsurface of material subjected to water jet peening, finite element modeling approach was adopted by using transient elastoplastic finite element analysis by considering an impingement of a set of droplets in succession to one another over a certain time period after which this pressure is released. The effectiveness of the proposed approach was demonstrated bv comparing the predicted residual stresses with those predicted by using the single set of droplets approach proposed by Rajesh et al. [6]. Finally, the practical relevance of the proposed approach was shown by comparing the predicted results with the experimental results obtained by water peening of 6063-T6 aluminium alloy.     

不同出射角度对气膜冷却流场的影响

采用RNGk-ε湍流模型对射流出射角度α为90o、正、负60o和正、负30o的气膜冷却流场进行了数值模拟,结合SIMPLEC算法求解了适体坐标系下的控制方程,近壁区流动采用两层模型的壁面函数法处理,结果给出了射流与主气流速度比R为2和4时的射流轨迹和速度场。结果表明:R和α值是影响气膜冷却流场的重要因素,R值增加,冷气射流对主流场影响区域增加,α值为负时,射流对主流场上游影响区域较大,当α值为30o时,射流影响区域减小;当α为正值时,随α值的减小,射流喷孔下游背风侧的分离现象逐渐消失。     

喷射成形高速钢中残余奥氏体的X射线衍射定量分析

文章阐述了X射线残余奥氏体定量分析的基本原理.经过对马氏体相和奥氏体相的衍射线的分别标定,选定马氏体和奥氏体的一条衍射线,分别测出它们的累积强度,用残余奥氏体定量分析公式来计算残余奥氏体体积百分含量.利用X射线衍射残奥定量测定方法,对喷射成形高速钢圆坯中残余奥氏体含量进行了测定,阐明了喷射成形圆坯密度变化的原因和机理,同时还对喷射成形过程中圆坯的冷却条件对残余奥氏体量的影响进行了合理的分析.为喷射成型新材料的工艺研究,提供了一种新的测试手段.     

C/Cu(Fe)复合材料制备工艺及性能研究

利用三步电沉积法制备C／Cu（Fe）复合材料预制丝，将预制丝缠绕成毛坯，采用真空热压法制备C／Cu（Fe）复合材料．研究表明，真空热压工艺对复合材料力学性能有很大影响，通过力学性能试验和对拉伸断口形貌的分析，得出了制备C／Cu（Fe）复合材料的最佳工艺．     

电液压脉冲水射流强化金属表面的研究

分析电液压脉冲水射流的工作原理及电液压脉冲水射流发生器的设计方案,对射流发生器的聚能效应和射流的运动进行探讨.实验表明采用电液压脉冲水射流冲击金属表面,的确能使金属表面的强度和硬度得到提高.     

自进式水射流钻进技术在煤层气开发中的应用

自进式高压水射流钻进技术是在煤层气勘探井内布置机械或水力扩孔装置,对准选定的煤层进行扩孔后,下入特制的转向工具,在300mm的曲率半径内实现由垂直转向水平进行钻进.自进式钻头由旋转喷嘴、钻屑整合装置及推力提供装置等组成,其带动为其提供高压水动力的特制胶管向前连续钻进.高压水通过高压胶管为自进式钻头提供动力,进行钻进、推动及排渣.该技术可以在同一煤层气勘探井内的不同煤层内完成多个水平钻孔,这些径向水平钻孔可以沟通新的瓦斯流动通道,从而大幅度地提高煤层气产量.