管板和传热管胀接应力应变的数值模拟及分析

蒸汽发生器是核电厂一回路与二回路的枢纽,传热管和管板的连接处为事故多发区,而机械加工过程残留的应力是引起裂纹的主要原因.应用有限元软件对某型蒸汽发生器中的传热管和管板的胀接过程进行瞬态模拟,得到不同胀接压力下的管板和传热管的残余应力和残余应变值,为传热管和管板最佳胀接参数的确定以及工作过程中应力腐蚀的预防提供理论依据.研究结果标明,管板孔表面的残余径向应力和残余径向应变值都是随胀接压力的增加而增加,且沿着轴向的变化规律相似.     

一种开关磁阻电动机功率变换器故障诊断方法

针对现有开关磁阻电动机功率变换器故障诊断方法存在可靠性不高等问题,提出了一种新型的功率管故障诊断方法。该方法以不对称半桥型功率变换器主电路为研究对象,以常见的功率管开路和短路2种故障情况为诊断对象,通过比较母线电流估算值和实测值来判断故障,结合故障相绕组电流实现故障相的识别,必要时通过中断测试来确定故障点。选取电动机空载、低速度和高速度运行等较难实现故障诊断的工况进行了试验分析,结果表明,该方法均能完成故障类型的定性及故障点的准确定位。     

基于循环维纳滤波的振动信号去噪算法研究

振动信号的去噪需要在滤除噪声的同时尽可能避免相位失真。传统的锐截止低通滤波器或FIR滤波器无法在去噪效果和线性相位之间取得平衡,难以满足振动信号的去噪需求。针对这一问题,将线性相位的维纳滤波算法引入到振动信号的去噪中,并结合振动信号的循环平稳特性,形成了振动信号的循环维纳滤波算法。文中以直接维纳滤波为基础对循环维纳滤波算法的原理进行了深入分析和仿真实现,并基于实测汽轮机振动信号对算法的去噪性能进行了讨论。理论分析及算法仿真表明,循环维纳滤波算法在保证线性相位的前提下有较好的去噪效果,能够解决传统去噪算法所存在的去噪效果与线性相位难以均衡的问题。     

Mobilising information systems scholarship for a circular economy: Review,synthesis, and directions for future research

One of today's grand societal challenges is to replace the current ‘take‐make‐waste’ economic model with a circular economic model that allows a gradual decoupling of economic activities from the consumption of finite virgin resources. While circular economy (CE) scholars have long lauded digital technologies such as sensors, distributed ledgers, or platforms as key enablers, our own community has not fully explored the potentials of information systems (IS) for a CE. Considering recent technological advances in software and hardware and our history of helping address wicked challenges, we believe the time is ripe to mobilise IS scholarship for a CE. Our findings from an interdisciplinary literature review show that research has primarily examined IS potentials for increasing efficiency of isolated intra‐organisational processes while neglecting the larger sustainability potential of IS to establish circular material flows—that is, slow down and close material loops across entire product lifecycles. In response, we propose directions for IS research that develop our knowledge of how IS can help understand and enact circular material flows to intensify and extend use of products and components and recycle waste materials. Our directions offer pathways to building and evaluating the problem‐solution pairing that could characterise a prolific CE‐IS relationship.     

蓝宝石高温光纤压力传感器的设计与仿真

针对高温环境下压力测量需求,提出采用蓝宝石材料来构造适用于特殊环境下的光纤高温法珀压力传感器。基于圆形膜片压力敏感原理设计了传感器敏感单元结构尺寸,通过Comsol有限元软件建立了敏感单元模型,对敏感膜片的表面位移及应力分布情况进行了仿真,验证了传感器设计的可靠性;同时分析了传感器的温敏效应,结果表明随温度升高,传感器的灵敏度会增大,会对压力测量产生误差,约为1.51kPa/℃,上述结果为蓝宝石高温压力传感器的结构和性能优化设计提供了有效指导。     

波浪对圆柱外接圆弧型防波堤绕射的解析计算

在微幅波绕射理论的基础上,使用特征函数展开法,推导了圆柱外接圆弧型防波堤复合结构的水波绕射的解析解,并据此计算了该结构所受到的波浪载荷以及绕射波面分布。计算结果表明:与单一圆柱相比,外接圆弧型防波堤的存在可明显降低作用于圆柱的波浪载荷和圆柱表面的波浪爬高;采用外接堤表面密实或透空而内圆柱表面透空的结构形式可以取得圆柱防浪的较佳效果;结构透空系数、波浪入射角度、外接堤张角、外堤半径与水深比、水深与波长比等因素的变化对绕射波浪作用均存在一定影响。     

Specific energy optimization in sawing of rocks using Taguchi approah简

This work aims at selecting optimal operating variables to obtain the minimum specific energy （SE） in sawing of rocks. A particular granite was sampled and sawn by a fully automated circular diamond sawblades. The peripheral speed, the traverse speed, the cut depth and the flow rate of cooling fluid were selected as the operating variables. Taguchi approach was adopted as a statistical design of experimental technique for optimization studies. The results were evaluated based on the analysis of variance and signal-to-noise ratio （S/N ratio）. Statistically significant operating variables and their percentage contribution to the process were also determined. Additionally, a statistical model was developed to demonstrate the relationship between SE and operating variables using regression analysis and the model was then verified. It was found that the optimal combination of operating variables for minimum SE is the peripheral speed of 25 m/s, the traverse speed of 70 cm/min, the cut depth of 2 cm and the flow rate of cooling fluid of 100 mL/s. The cut depth and traverse speed were statistically determined as the significant operating variables affecting the SE, respectively. Furthermore, the regression model results reveal that the predictive model has a high applicability for practical applications.     

高精度冷轧不锈钢管生产

介绍了用ＬＤ型冷轧管机生产高精度冷轧不锈钢管的经验和质量保证措施。     

Special-shaped tube drawing forming and conformal optimization of die cavity

Aiming at the issues in quick processing and modeling design of drawing special-shaped tube die, by Conformal Mapping Theory and the numerical trigonometry method of interpolation between odd points and even points, the conformal mapping function is obtained. As the result, three-dimension drawing forming were converted into that of two-dimension problems, and the plastic stream function was analyzed, die cavity modeling and its optimized function were set up. Combining with modern processing technology, NC program and CAM of die cavity can be realized. Taking the drawing forming of hexagon tube with arc radii r and ellipse-shaped tube as instances, the drawing die cavity optimization of special-shaped tube was achieved, as well as, the changing principle of wall thickness was analyzed.