激光焊接技术在轨道交通车辆中的应用

为解决轨道交通车辆不锈钢车体电阻点焊的外观质量差、密封性差、效率低等缺点,对部分熔透激光焊接工艺在不锈钢车体焊接中的应用开展了研究。研究包括:部分熔透激光叠焊原理、参数优化试验、显微组织分析、疲劳性能分析,以及激光焊接不锈钢车辆侧墙的结构改进。研究结果表明,不锈钢车体焊接中采用部分熔透激光叠焊工艺,可以获得高质量的表面状态及疲劳强度,车体结构强度高于EN12663标准中的要求。     

基于未确知测度理论的隧道施工瓦斯灾害风险评价

选取煤层厚度、煤层瓦斯含量、回风流平均瓦斯浓度、相对瓦斯涌出量、岩石类型、连通封闭性、深度值、隧道跨度、隧道长度、通风风速和涌水量等11项瓦斯灾害指标作为隧道施工瓦斯灾害风险评价指标体系,并建立各指标的等级标准。将序关系分析法(G1)和反熵权法(AEW)运用拉格朗日乘子法确定组合权重,构建各指标的单指标测度函数,并计算出各指标的综合测度评价向量。为了优化未确知测度置信度识别准则,引进集对分析(SPA)关联系数确定各隧道的瓦斯灾害风险等级。并对24个瓦斯隧道进行瓦斯灾害评价,并和FDA法评价结果和现场实测结果进行对比,精度达到91.7%,基本符合实际情况,表明了该评价方法合理有效,可为隧道施工瓦斯灾害评价提供理论参考。     

Experimental field study of floater motion effects on a main bearing in a full-scale spar floating wind turbine

In this paper we present a full-scale experimental field study of the effects of floater motion on a main bearing in a 6 MW turbine on a spar-type floating substructure. Floating wind turbines are necessary to access the full offshore wind power potential, but the characteristics of their operation leave a gap with respect to the rapidly developing empirical knowledge on operation of bottom-fixed turbines. Larger wind turbines are one of the most important contributions to reducing cost of energy, but challenge established drivetrain layouts, component size envelopes and analysis methods. We have used fibre optic strain sensor arrays to measure circumferential strain in the stationary ring in a main bearing. Strain data have been analysed in the time domain and the frequency domain and compared with data on environmental loads, floating turbine motion and turbine operation. The results show that the contribution to fluctuating strain from in-plane bending strain is two orders of magnitude larger than that from membrane strain. The fluctuating in-plane bending strain is the result of cyclic differences between blade bending moments, both in and out of the rotor plane, and is driven by wind loads and turbine rotation. The fluctuating membrane strain appears to be the result of both axial load from thrust, because of the bearing and roller geometry, and radial loads on the rotating bearing ring from total out-of-plane bending moments in the three blades. The membrane strain shows a contribution from slow-varying wind forces and floating turbine pitch motion. However, as the total fluctuating strain is dominated by the intrinsic effects of blade bending moments in these turbines, the relative effect of floater motion is very small. Mostly relevant for the intrinsic membrane strain, sum and difference frequencies appear in the measured responses as the result of nonlinear system behaviour. This is an important result with respect to turbine modelling and simulation, where global structural analyses and local drivetrain analyses are frequently decoupled.     

Short-term statistics of ice loads on ship bow frames in floe ice fields: Full-scale measurements in the Antarctic ocean

Ship operation and ice loading in floe ice fields have received considerable interest during recent years. There have been several numerical simulators developed by different institutes which can simulate ship navigation through floe ice fields and estimate ship performance and local ice loads. However, public data obtained from full-scale measurement covering comprehensively ship performance and ice loads under various ice thicknesses, concentrations and floe sizes are rare. The 2018/19 Antarctic voyage of the Polar Supply and Research Vessel (PSRV) S.A. Agulhas II gathered considerable data of the ship in floe ice fields under various thicknesses, concentrations, and floe sizes. The aim of this paper is to carry out statistical analysis to seek suitable probability distributions which adequately fit the measured ice load and therefore suitable to be used as parent distributions for long-term estimation. For this aim, three categories of probability distributions, namely standard distributions, truncated distributions and mixture distributions are tested. It is found that truncated distributions can fit the load data better than standard distributions bounded at the threshold. In addition, mixture distributions are shown to have promising features, which fit the data well and are able to separate distribution components. Subsequentially, the well-performed distributions are used as parent distributions to make long-term load estimations. The estimation results demonstrate that long-term estimations are sensitive to the selection of parent distribution, which addresses the importance of finding correct distribution to model short-term ice loads. The data of ten selected cases will be published for the use of other researchers.     

激光熔覆涂层的组织特点与裂纹产生的机理探讨

碳钢、铸铁表面分别采用激光熔覆N i基、Fe基合金涂层,观察并分析了熔覆涂层界面及其显微组织和硬度特点,探讨了碳钢表面激光熔覆层裂纹产生的机理.     

非线性激光防护及光限幅技术

介绍了激光防护技术的基本概念及性能要求。阐述了基于非线性光学效应的光限幅器的基本原理及材料。简要分析了进一步研究的方向。     

D—MS定速式摩擦试验机微机检测系统

本文介绍了与D—MS定速式摩擦试验配套的微机检测系统。D—MS定速式摩擦试验机原来的测量及记录装置落后,自动化程度差,该微机检测系统能显著改善其性能。     

应用激光捕获显微切割技术制备肺癌蛋白质组学研究样品

目的探讨应用激光捕获显微切割(laser capture microdissection,LCM)技术获取高同质性肺癌组织细胞及正常对照肺泡上皮细胞的方法及可行性。方法将新鲜肺癌组织标本及其配对正常组织常规制备8μm冰冻切片,采用改良的HE方法染色;应用LCM技术大宗切割肺鳞癌、腺癌及正常对照肺泡上皮细胞;选择性获取同质肺癌细胞和配对正常细胞。结果通过LCM技术可以准确、快速地分离癌细胞、间质及其他坏死组织,得到同质性不低于95%的肿瘤细胞和正常细胞。按照Duration 15.5 s的激光脉冲频率和平均8 000 shots条件,既可保证每个帽子的细胞收集数量,也能够有效地缩短实验时间,提高实验可控性,从而使操作过程标准化。结论应用LCM技术可以成功获取同质肺癌细胞和正常细胞。其所需标本量少、组织同质性高、操作过程稳定、可控性好,是肺癌分子生物学及蛋白质组学研究有价值的样品制备方法。     

浅析内业工作在施工中的作用

通过对内业工作的重要性的阐述 ,论述了内业工作与外业工作的紧密联系 ,着重说明了内业工作在公路建设中的主要地位     

微创手术机器人视觉定位系统的研究

根据立体视觉的基本原理，建立摄像机标定模型和立体视觉模型，设计了基于微创手术机器人的视觉定位系统．介绍了相应图像处理软件的设计，实现对目标的准确识别和精确定位．实验证明该方案有较好的定位效果，同时分析了引起误差的原因．