黔桂线关节式电分相引起线索烧损原因及措施

针对黔桂线上电力机车通过关节式电分相时,引起牵引变电所跳闸,发生电弧烧损接触网线索的问题,分析了电力机车过分相引起线索烧损的原因,提出了安装自动断载装置、加强机车监控、加强车顶绝缘设备的维护、优化关节式电分相结构和参数检调等防范措施,从而减少了关节式电分相引起变电所跳闸及烧损线索的情况,保障了电力设备的安全及电气化铁路的正常运营。     

国道208线司庄2号桥的加固与维修

主要介绍了国道208线司庄2号桥的结构损坏情况,阐述了维修加固设计原则和有关施工工艺,通过加固后动、静栽试验对比及跟踪观测和定期检查,表明加固效果良好。     

Modeling the effect of environmental conditions on reliability of wind turbines

The climate condition of a wind farm has a significant influence on the reliability of wind turbines. The climate condition varies with season in a year and hence the reliability changes in a complex way. The purpose of this paper is to model the effect of climate condition on field reliability of wind turbines. The reliability is measured by monthly-averaged mean time between failures(MTBF), and the climate conditions are described by variables of monthly-averaged temperature, relative humidity, rainfall and wind speed. Referring to the physicsof-failure models in accelerated life testing(ALT), we develop a quantitative relation between the MTBF and the climate variables. For a set of field data, the model parameters are estimated by regression, and the insignificant variables are gradually deleted based on the P-value of the regression coefficients. The resulting model is useful for maintenance workload forecasting and preventive maintenance planning, and has a potential to be used in online failure prediction.     

空化对GDI喷嘴内部流动及喷雾特性的影响

采用两相流非线性空化模型和Huh-Gosman喷雾模型对GDI多孔喷油器喷嘴内部流动和喷雾特性进行模拟。通过流量及喷雾试验对计算模型进行了验证,研究了喷嘴内空化现象对流动及喷雾特性的影响,并从抑制空化、提升流量的角度研究了喷嘴内部流动空化的影响因素及规律。研究结果显示:高压汽油在喷嘴内的流动存在明显的空化现象,空化导致的有效流通面积减小是喷嘴流量减小的原因。针阀升程增加,喷嘴流量先增加较快,后趋于平缓。喷孔的不均匀分布导致各喷孔内的空化状况不同,进而产生流量差异。空化作用也使得喷雾射流在喷孔出口截面的流动参数产生差异,影响喷雾的落点分布和喷雾形态。通过优化喷孔k系数和喷孔入口圆角半径可显著提高喷孔流量。