核电厂接地设计中的关键问题

随着核电厂自动控制水平的提高和数字化控制系统的引入,电子设备所处建筑物中的电磁环境也越趋复杂,无线通讯设备、大功率变频设备等的应用使得环境中高频干扰信号的比重在加大,接地设计对改善设备的电磁干扰环境起着关键的作用。将最新的IEC标准对接地和防雷保护方面的规定及工业实践应用于核电厂的接地设计,通过采用格栅形共用接地网络、电缆屏蔽层两端接地和并联接地导体等技术以改善核电厂的电磁环境,满足DCS等敏感设备的运行要求,解决核电厂在接地系统设计过程中为了满足电磁兼容要求需要重点关注的技术问题,研究成果可应用于其他类似电力工程。     

基于电压向量的数字化母线保护电流同步方法

采样数据同步是智能变电站继电保护的关键问题。当采样数据通过过程层网络传输时,保护装置依赖于时钟源同步。提出了一种基于电压向量的数字化母线保护电流同步方案,在原有同步方案失效并导致合并单元采样失步的情况下,通过电压向量的相位差对采样数据进行同步处理,仍可保证母线保护继续投入运行。分析了同步方案的原理,介绍了同步方案的系统接线,给出了实施方案的细节:通过正序电压计算间隔采样的时间差;通过抛物线二次插值方法对采样数据进行同步处理;发生三相PT断线时需退出同步方案。RTDS数模实验结果表明同步方案可保证各种工况下母线差动保护功能的正确性,证明了同步方案的有效性和可行性。     

敞口消解-ICP-MS测定微合金钢中4种微量元素的方法研究

采用HNO3＋HCl混合酸消解体系敞口消解试样,选取74Ge作为测定48Ti,52Cr,59Co,61Ni的内标元素,建立了微合金钢中微量元素钛、铬、钴、镍的电感耦合等离子体质谱（ICP-MS）测定方法。该方法线性关系良好（相关系数r=0.99985～0.99998）,检出限为6pg·g-1～39pg·g-1,平均加标回收率达到98%～102%,方法精密度好,相对标准偏差（n=9）在0.47%～2.04%之间。所建立的分析方法实现了对微合金钢样品中4种微量元素的测定,实际样品的测定结果与参考值相符。     

基于VB的短消息实现及在监控系统中的应用

介绍了GSM无线模块短消息发送的相关AT命令和模式,利用VB语言实现短消息发送的核心程序,以及监控系统的报警配置,实现了监控系统报警信息的短消息发送。     

锂硫电池用气相生长碳纤维增强硫-多壁碳纳米管复合正极的影响(英文)

制备了锂硫电池用硫-多壁碳纳米管纳米复合材料,并分别采用气相生长碳纤维(VGCFs)和导电炭黑作为复合正极的导电添加剂,通过形貌表征(SEM)、恒流充放电测试和交流阻抗分析(EIS)研究VGCFs对硫-多壁碳纳米管复合正极的影响。结果表明:采用VGCFs作添加剂的硫-多壁碳纳米管复合电极具有三维网状结构,其首次放电比容量为1254 mA·h/g,40次循环后容量保持在716 mA·h/g。与采用导电炭黑为添加剂的电极相比,采用VGCFs为添加剂的电极具有更高的活性物质利用率和更好的循环稳定性。相互搭接的纤维状VGCFs可形成稳定的导电网络,抑制正极材料及残存放电产物的团聚堆积,维持电极的多孔性,从而改善电池的电化学性能。     

污水处理厂曝气系统的检修

因前期生化池的土建施工及曝气设施的安装存在一定的缺陷,某污水处理厂曝气系统出现故障,亟需检修。文章从检修前的准备工作,具体检修过程的实施,及检修效果的检验等环节论述了该曝气系统的整个检修过程,并提出了相应环节的注意事项。     

工业园区污水处理厂的运行与管理

因管网来水水质、水量波动大,给工业园区污水处理厂出水水质稳定达标排放带来了一定的难度。文章从运行与管理的角度,论述了确保出水水质稳定达标的有效途径,如加强进水口的监控,定期对管网进行排查,优化生产工艺指标,加强设备的维护保养,不断提升员工的工作技能及规范厂内日常管理。     

Influence of grain boundary carbides on mechanical properties of high nitrogen austenitic stainless steel

Precipitation behavior of grain boundary carbides and its influence on mechanical properties and fracture mechanism of the high nitrogen austenitic stainless steel produced by different processing methods were studied. The simulation software Thermo-calc was applied to analyze the effects of element content on precipitation of carbides. The results show that hot-rolled plate has higher strength, but solution-treated one followed by water quenching has excellent combination of strength and ductility (toughness). M₂₃C₆ is the main precipitate and deteriorates the toughness of the steel obviously when it precipitates along grain boundaries. In this case, intergranular fracture is the predominant failure mechanism and the fracture surface is characterized by the shape of rock candy. The toughness at −40 °C is decreased by 53% when small amount of carbides precipitates during sand cooling process after solution treatment. The simulation results exhibit that with the decrease of C content, both the precipitation quantity and precipitation temperature of M₂₃C₆ decrease. Cr and N have no influence on precipitation quantity of M₂₃C₆, but the precipitation temperature will increase with the increase of Cr and the decrease of N.     

An empirical approach to explain the material removal rate for copper chemical mechanical polishing

In this paper, an empirical expression was deduced based on the experimental data for material removal rate of copper chemical mechanical polishing. The parameters of this expression includes the initial chemical corrosion rate(MRR₀), the corrosion inhibition efficiency(k) and the mechanical abrading rate(MRR_M). The deduced empirical expression revealed that under certain slurry systems, the corrosion inhibition efficiency may always keep unchanged, which may be useful to characterize the inhibition properties of different inhibitors.