T400工艺板在飞剪电控系统改造中的应用

本文在起停式飞剪的电控系统改造中,采用基于T400工艺模块的分级分布式计算机控制系统,建立了控制系统的数学模型,并针对该控制系统进行了MATLAB仿真。仿真结果表明,该控制系统设计合理,调节系统的动、静态特性较好。     

混凝土养护期间HRB400钢筋钝化行为研究

为了研究HRB400钢筋在模拟养护阶段混凝土孔隙液中表面钝化膜的生长过程,采用3种电化学测试技术(开路电位、电化学阻抗谱、动电位极化曲线)研究钢筋表面钝化膜的性能随着浸泡时间的变化特征,此外通过XPS对稳定钝化膜的成分与结构进行分析。结果表明,同传统钢筋材料一样,HRB400钢筋在模拟混凝土养护条件的溶液中展现出良好的耐蚀性能,浸泡5 d后便能够生成稳定钝化膜。XPS分析发现钢筋钝化膜为双层结构,内层以二价铁离子化合物为主,外层主要由三价铁离子化合物组成。     

基于西门子S7—400PLC的包钢转炉自动化系统设计与实现

该文针对包钢220吨转炉设计并实现了一套完整的自动控制系统。主要介绍了该系统的结构与硬件配置以及对所采用的软件的评估,还就系统中的数据通信、氧枪定位、汽包三冲量调节、系统的监控等问题进行了讨论,并详细分析了有关控制回路的调试和实施。     

Parameterized complexity of control problems in Maximin election

Elections are a central model in a variety of areas. This paper studies parameterized computational complexity of five control problems in the Maximin election. We obtain the following results: constructive control by adding candidates is W[2]-hard with respect to the parameter “number of added candidates”; both constructive and destructive control by adding/deleting voters are W[1]-hard with respect to the parameter “number of added/deleted voters”.     

西门子S7系列PLC在成都地铁BAS系统中的应用

本系统以西门子S7-414H冗余控制器为主站,多台S7—200PLC和S7—300PLC为从站,通过光纤链路模块OLM组成冗余光纤环网,实现地铁设备监控系统的完美控制。文章重点介绍了控制工艺背景、主／从网络组成构架、硬件配置及软件编程．要点、系统中包含的PROFIBUS-DP、MODBUS、网络读写等通讯协议出现的问题及解决方法、调试后达到的效果及应用体会。     

冗余控制系统在炼铁厂TRT发电装置中的应用

鉴于TRT高炉煤气发电装置的重要性且对其可靠性的要求较高,因而该发电装置的控制系统选用了西门子S7—400H冗余系统。文中简述了TRT高炉煤气发电装置的构成,介绍了S7—400H冗余系统的硬件结构、模块参数和各程序模块的具体功能。该控制系统投运后,TRT高炉煤气发电装置运行可靠,效果良好。     

铌微合金化HRB400热轧带肋钢筋在高速线材机上的生产实践与探讨

水钢第一轧钢厂在高速线材轧机上生产铌微合金化HRB400热轧带肋螺纹钢筋,除成品孔型采用碳化钨螺纹辊环外,其余全部使用原孔型系统,产品力学性能达到了Ⅲ级螺纹钢标准。同时对影响钢筋力学性能、金相组织的因素进行了分析和探讨。     

HRB400带肋钢筋切分工艺的实践

简明介绍了攀钢集团成都钢铁有限公司棒材连轧生产线应用切分轧制技术生产HRB400小规格带肋钢筋的工艺、设备、技术、坯料控制特点及生产中值得注意的几个问题。     

Stress-corrosion cracking of a monel 400 tube

A bent Ni-Cu Monel 400 alloy tube, which operated as part of a pipeline in a petrochemical distillery installation, failed by through-thickness cracking. The pipeline was used to carry a stream of gaseous hydrocarbons containing hydrochloric acid (HCl) into a reaction tower. The tower provided a caustic solution (NaOH) to remove HCl from the stream, before the latter was directed to a burner. Metallographic examination showed that the cracks were intergranular and were frequently branched. Although nominal chemical composition of the component was found within the specified range, electron dispersive analysis by X-ray (EDXA) indicated significant segregation of sulfur and chlorine on grain boundaries. Failure was attributed to hypochlorous-acid (HClO)-induced stress-corrosion cracking (SCC). The HClO was formed by the reaction of HCl with atmospheric O₂, and the oxygen entered the tube during shutdowns/startups of the installation. Residual stresses, originating from the in situ bend forming of the tube during assembly of the line, provided a driving force for crack growth, and the segregation of sulfur on grain boundaries enhanced the susceptibility of the material to cracking.     

400mm厚连铸坯轧制时缺陷的压合模拟

对某宽厚板厂最新投产的400mm连铸坯,以刚-粘塑性有限元模拟分析了其轧制Q345特厚钢板时的缺陷压合过程和临界压合条件。结果表明：在足够的压下率下,特厚板中心矩形裂纹能够被压合;缺陷尺寸、轧辊半径和坯料厚度对缺陷压合影响很大。缺陷尺寸和轧辊半径越大、坯料厚度越小,压合所需的临界压下率越小;在1120mm×4300m...