Advances in analysis of total uncertainties in a semi‐invasive residual stress measurement method

The ability to characterise residual stress distribution accurately and over different length scales, particularly deep into an engineering part, plays a significant role in assessing structural integrity. Two most commonly used techniques to measure residual stress fields deep into engineering components include neutron diffraction (ND) and deep‐hole drilling (DHD). As the measurements depend on several physical quantities, they are susceptible to error. The error or uncertainties may turn substantial and compromise the suitability of the results. Although noninvasive, the neutron diffraction technique is neither readily available nor portable and is limited to approximately 60‐mm‐thick specimen; errors associated with results become unacceptable at greater flight paths. Moreover, a mock‐up representing the engineering component is normally used in the ND technique. In contrast, the DHD technique is portable and measures residual stresses with high spatial resolution. An error propagation technique was applied to develop an error analysis procedure taking into consideration various stages of the DHD method and successfully applied to different DHD measurements. An essential feature comprising the effect of plasticity due to the creation of reference hole in the DHD procedure has not yet been taken into account in the error analysis procedure. This paper briefly describes how the uncertainties due to the creation of the initial reference hole can be determined. The effect of plasticity in the drilling procedure is quantified in this study. This error is combined with other sources of error and formulated to determine the total error. An incremental DHD technique was used to measure the complex triaxial residual stress field in an as‐welded circular disc, and the measured data were used to illustrate the total error using the error analysis method developed in the study.     

Electrocatalytic hydrogen evolution of highly dispersed Pt/NC nanoparticles derived from porphyrin MOFs under acidic and alkaline medium

Platinum (Pt)-based electrocatalysts often exhibit an excellent electrocatalytic activity for hydrogen evolution due to their best hydrogen bonding energy, but materials with high Pt content can easily cause aggregation and reduce their efficiency. In this article, Pt-based electrocatalysts with uniform dispersion and high efficiency were fabricated by a successive hydrothermal and calcination method, and the uniformly distributed Pt nanoparticle was mainly due to the anchoring effect of porphyrin ring in porphyrin MOFs, which made the minimized agglomerations as much as possible in the process of high temperature calcination. The results showed that the optimal Pt/NC-850 could reach current density of 10, 50 and 100 mA cm^?2 with only 17, 82 and 152 mV overpotentials, while the Pt/NC-850 also exhibited a superior stability and durability under acidic medium. Impressively, the Pt/NC-850 also had an excellent activity, good stability and durability under alkaline medium.     

基于带约束三角剖分的三维巷道建模方法

提出了具有可行性的巷道模型实现方法，将巷道模型抽象为顶盘面、底盘面和侧面3部分。在获取巷道顶盘（或底盘）边界测量数据的条件下，提出了采用约束三角剖分的方法生成巷道模型的上下底盘面，利用两段成面法生成巷道模型的侧面，最后将这些面组合成巷道模型。该方法可以一次性地生成某一开采层面的全部巷道模型，并已成功地运用到以GeoView为平台的“数字紫金”项目中，取得了良好的效果。     

上海磁悬浮列车工程基岩水准标设计与施工

上海磁悬浮列车工程专门设计施工了两座基岩水准标，作为沉降监测的测量基准。该基岩标较以往监测标志有重大改进，并兼有高程控制与平面位置控制的作用。本文介绍其设计原理、结构特点与施工技术。     

大气监测SO_2质控中遇到的问题及处理方法

介绍了大气监测SO2中遇到的几个问题及处理方法,在环保化验中对SO2的质量控制起到指导和帮助作用。     

拱圈在基坑支护中的应用

珠海市海珠广场基坑支护工程采用双排搅拌桩帷幕墙止水、拱圈支护结构挡土方案。介绍了拱圈支护结构的设计及施工中应注意的问题。经过监测，采用拱圈支护结构变位很小。     

铁基粉末齿环材料的制备

采用高能球磨法制备Fe-2Mn-2Cu-Mo-C-P粉末．研究了粉末形态的变化规律，以及压坯密度、烧结密度与球磨时间的关系．结果表明，球磨8h的粉末经压制烧结，材料密度为7．21g／cm^3。退火后Hv5值为230-240。该材料具有良好的热塑性及硬度，适合粉末热锻法生产齿环．     

东鞍山烧结厂磁浮流程可行性的研究

选用立环脉动高梯度强磁机和新研制的新型捕收剂，东鞍山贫赤铁矿石经实验室试验，采用两段连续磨矿－强磁抛尾－混磁精再磨－正浮选工艺流程，可得到品位大于64％的精矿、铁回收率超过70％的指标。