剩余使用寿命(Remaining useful life,RUL)预测是大型设备故障预测与健康管理(Prognostics and health management,PHM)的重要环节,对于降低设备维修成本和避免灾难性故障具有重要意义.针对RUL预测,首次提出一种基于多变量分析的时序图...剩余使用寿命(Remaining useful life,RUL)预测是大型设备故障预测与健康管理(Prognostics and health management,PHM)的重要环节,对于降低设备维修成本和避免灾难性故障具有重要意义.针对RUL预测,首次提出一种基于多变量分析的时序图推理模型(Multivariate similarity temporal knowledge graph,MSTKG),通过捕捉设备各部件的运行状态耦合关系及其变化趋势,挖掘其中蕴含的设备性能退化信息,为寿命预测提供有效依据.首先,设计时序图结构,形式化表达各部件不同工作周期的关联关系.其次,提出联合图卷积神经网络(Convolutional neural network,CNN)和门控循环单元(Gated recurrent unit,GRU)的深度推理网络,建模并学习设备各部件工作状态的时空演化过程,并结合回归分析,得到剩余使用寿命预测结果.最后,与现有预测方法相比,所提方法能够显式建模并利用设备部件耦合关系的变化信息,仿真实验结果验证了该方法的优越性.展开更多
Scarce resources,precedence and non-determined time-lag are three constraints commonly found in small and medium manufacturing enterprises(SMEs),which are deemed to block the application of workflow management system(...Scarce resources,precedence and non-determined time-lag are three constraints commonly found in small and medium manufacturing enterprises(SMEs),which are deemed to block the application of workflow management system(WfMS). To tackle this problem,a workflow scheduling approach is proposed based on timing workflow net(TWF-net) and genetic algorithm(GA). The workflow is modelled in a form of TWF-net in favour of process simulation and resource conflict checking. After simplifying and reconstructing the set of workflow instance,the conflict resolution problem is transformed into a resource-constrained project scheduling problem(RCPSP),which could be efficiently solved by a heuristic method,such as GA. Finally,problems of various sizes are utilized to test the performance of the proposed algorithm and to compare it with first-come-firstserved(FCFS) strategy. The evaluation demonstrates that the proposed method is an overwhelming and effective approach for scheduling the concurrent processes with precedence and resource constraints.展开更多
基金Supported by the Postdoctoral Science Foundation of China(No.2015M572022)the National Natural Science Foundation of China(No.51175304)
文摘Scarce resources,precedence and non-determined time-lag are three constraints commonly found in small and medium manufacturing enterprises(SMEs),which are deemed to block the application of workflow management system(WfMS). To tackle this problem,a workflow scheduling approach is proposed based on timing workflow net(TWF-net) and genetic algorithm(GA). The workflow is modelled in a form of TWF-net in favour of process simulation and resource conflict checking. After simplifying and reconstructing the set of workflow instance,the conflict resolution problem is transformed into a resource-constrained project scheduling problem(RCPSP),which could be efficiently solved by a heuristic method,such as GA. Finally,problems of various sizes are utilized to test the performance of the proposed algorithm and to compare it with first-come-firstserved(FCFS) strategy. The evaluation demonstrates that the proposed method is an overwhelming and effective approach for scheduling the concurrent processes with precedence and resource constraints.
文摘目的:探讨于第一产程不同时期使用硬膜外阻滞分娩镇痛对母婴结局的影响。方法:选取足月初产妇144例,未实施分娩镇痛者为对照组,实施分娩镇痛者为观察组,并按照实施分娩镇痛的时机分为观察组1(宫口扩张<3 cm)、观察组2(宫口扩张3~4 cm)和观察组3(宫口扩张>4 cm)。比较各组产程时间、中转剖宫产率、会阴侧切率、助产分娩率及新生儿Apgar评分。结果:观察组1组的第一产程时间均显著长于其他组(P<0.01),各组第二产程、第三产程时间比较差异均无统计学意义(P>0.05)。观察组自然分娩率高于对照组(P<0.05);观察组分娩中转剖宫产率低于对照组(P<0.01)。各观察组间侧切分娩率、助产分娩率比较差异均无统计学意义(P>0.05);各观察组比较观察组3组自然分娩率显著高于观察组1组(P<0.01),观察组3组中转剖宫产率显著低于观察组1组(P<0.01)。观察组1、2、3组及对照组新生儿的1 min Apgar评分、5 min Apgar评分比较差异均无统计学意义(P>0.05)。结论:应用分娩镇痛技术可显著降低分娩中转剖宫产率,减少剖宫产术对母儿造成的不良影响,可在临床工作中推广和应用,可优先选择宫口扩张3~4 cm时应用分娩镇痛。
