Aiming at the difficulty of mining fault prognosis starting points and constructing prognostic models for remaining useful life(RUL)prediction of rolling bearings,a RUL prediction method is proposed based on health in...Aiming at the difficulty of mining fault prognosis starting points and constructing prognostic models for remaining useful life(RUL)prediction of rolling bearings,a RUL prediction method is proposed based on health indicator(HI)extraction and trajectory-enhanced particle filter(TE-PF).By extracting a HI that can accurately track the trending of bearing degradation and combining it with the early fault enhancement technology,early abnormal sample nodes can be mined to provide more samples with fault information for the construction and training of subsequent prediction models.Aiming at the problem that traditional degradation rate models based on PF are vulnerable to HI mutations,a TE-PF prediction method is proposed based on comprehensive utilization of historical degradation information to timely modify prediction model parameters.Results from a rolling bearing prognostic study show that prediction starting points can be accurately detected and a reasonable prediction model can be conveniently constructed by the RUL prediction method based on HI amplitude abnormal detection and TE-PF.Furthermore,aiming at the RUL prediction problem under the condition of HI mutation,RUL prediction with probability and statistics characteristics under a confidence interval can be obtained based on the method proposed.展开更多
为解决雨水泵站运行过程中存在的水泵频繁启停问题,提出一种水泵机组启停优化方法.该方法通过分析泵站的设计参数和水泵机组运行原理,建立启泵水位优化模型,并运用暴雨洪水管理模型(storm water management model,SWMM)和粒子群优化算法...为解决雨水泵站运行过程中存在的水泵频繁启停问题,提出一种水泵机组启停优化方法.该方法通过分析泵站的设计参数和水泵机组运行原理,建立启泵水位优化模型,并运用暴雨洪水管理模型(storm water management model,SWMM)和粒子群优化算法(particle swarm optimization algorithm,PSO)对模型求解,最终得到水泵机组的最优启泵水位.通过实例将优化方法与传统的人工调试方法进行对比,验证了其可行性.研究结果表明:采用优化方法得到的启泵水位可使机组启停次数达到最小,实现了较好的水泵启停效果.同时优化方法也避免了复杂的人工调试过程,得出的优化结果为雨水泵站启泵水位的选取提供参考.展开更多
针对甲醇发动机难以形成浓度合适的混合气而造成冷起动困难的问题,以一台应用自主开发的进气道低压空气辅助喷射系统(air assisted port injection,AAPI)的单缸甲醇发动机为研究对象开展试验研究,探究不采用辅助措施通过AAPI喷射实现甲...针对甲醇发动机难以形成浓度合适的混合气而造成冷起动困难的问题,以一台应用自主开发的进气道低压空气辅助喷射系统(air assisted port injection,AAPI)的单缸甲醇发动机为研究对象开展试验研究,探究不采用辅助措施通过AAPI喷射实现甲醇高雾化对甲醇发动机冷起动的影响及规律。试验表明AAPI明显加快了甲醇发动机冷起动前可燃混合气的形成速率。AAPI甲醇发动机着火前过量空气系数λ的平均变化率值和峰值变化率分别是普通喷射方式的3.2倍和2.26倍。点火时刻对AAPI甲醇发动机冷起动影响较大,为使AAPI甲醇发动机的冷起动性能最优,需配合合适的点火时刻,试验条件下最佳点火时刻为活塞压缩上止点前20°。AAPI甲醇发动机的冷起动性能受环境温度影响较大,随着环境温度的降低,甲醇发动机冷起动时间增长;不采用辅助措施,AAPI甲醇发动机在5℃时能实现可靠冷起动。展开更多
基金supported by the National Key Research and Development Program of China (No.2018YFB1702401)National Natural Science Foundation of China (Grant No.51975576,51475463).
文摘Aiming at the difficulty of mining fault prognosis starting points and constructing prognostic models for remaining useful life(RUL)prediction of rolling bearings,a RUL prediction method is proposed based on health indicator(HI)extraction and trajectory-enhanced particle filter(TE-PF).By extracting a HI that can accurately track the trending of bearing degradation and combining it with the early fault enhancement technology,early abnormal sample nodes can be mined to provide more samples with fault information for the construction and training of subsequent prediction models.Aiming at the problem that traditional degradation rate models based on PF are vulnerable to HI mutations,a TE-PF prediction method is proposed based on comprehensive utilization of historical degradation information to timely modify prediction model parameters.Results from a rolling bearing prognostic study show that prediction starting points can be accurately detected and a reasonable prediction model can be conveniently constructed by the RUL prediction method based on HI amplitude abnormal detection and TE-PF.Furthermore,aiming at the RUL prediction problem under the condition of HI mutation,RUL prediction with probability and statistics characteristics under a confidence interval can be obtained based on the method proposed.
文摘针对甲醇发动机难以形成浓度合适的混合气而造成冷起动困难的问题,以一台应用自主开发的进气道低压空气辅助喷射系统(air assisted port injection,AAPI)的单缸甲醇发动机为研究对象开展试验研究,探究不采用辅助措施通过AAPI喷射实现甲醇高雾化对甲醇发动机冷起动的影响及规律。试验表明AAPI明显加快了甲醇发动机冷起动前可燃混合气的形成速率。AAPI甲醇发动机着火前过量空气系数λ的平均变化率值和峰值变化率分别是普通喷射方式的3.2倍和2.26倍。点火时刻对AAPI甲醇发动机冷起动影响较大,为使AAPI甲醇发动机的冷起动性能最优,需配合合适的点火时刻,试验条件下最佳点火时刻为活塞压缩上止点前20°。AAPI甲醇发动机的冷起动性能受环境温度影响较大,随着环境温度的降低,甲醇发动机冷起动时间增长;不采用辅助措施,AAPI甲醇发动机在5℃时能实现可靠冷起动。
