Optimization method of urban rail train operational plan based on O-D time-varying demand

Purpose–Under the constraints of given passenger service level and coupling travel demand with train departure time,this study optimizes the train operational plan in an urban rail corridor to minimize the numbers of train trips and rolling stocks considering the time-varying demand of urban rail passenger flow.Design/methodology/approach–The authors optimize the train operational plan in a special network layout,i.e.an urban rail corridor with dead-end terminal yard,by decomposing it into two sub-problems:train timetable optimization and rolling stock circulation optimization.As for train timetable optimization,the authors propose a schedule-based passenger flow assignment method,construct the corresponding timetabling optimization model and design the bi-directional coordinated sequential optimization algorithm.For the optimization of rolling stock circulation,the authors construct the corresponding optimization assignment model and adopt the Hungary algorithm for solving the model.Findings–The case study shows that the train operational plan developed by the study’s approach meets requirements on the passenger service quality and reduces the operational cost to the maximum by minimizing the numbers of train trips and rolling stocks.Originality/value–The example verifies the efficiency of the model and algorithm.

PXR、PPARα激动所致小鼠肝增大的昼夜节律研究

肝脏大小受生物钟控制并具有昼夜节律。孕烷X受体(pregnane X receptor,PXR)和过氧化物酶体增殖物激活受体α (peroxisome proliferator-activated receptor α,PPARα)是核受体超家族的重要成员。本课题组前期发现,鼠源激动剂孕烯醇酮16α-腈(pregnenolone 16α-carbonitrile,PCN)激动PXR、匹立尼酸(pirinixic acid,WY-14643)激动PPARα后均显著促进小鼠生理性肝增大及部分肝切除术后肝再生。但是,PXR、PPARα激动所致肝增大的昼夜变化尚不清楚。因此,本研究考察连续3天不同时辰给予雄性C57BL/6小鼠玉米油、PCN或WY-14643后肝脏大小及生物钟相关基因等的变化。本动物实验方案经中山大学实验动物伦理委员会审核批准(批准号:SYSU-IACUC-2023-001613、SYSU-IACUC-2023-001783)。结果表明,连续3天不同时辰给予PXR、PPARα激动剂均显著促进小鼠肝增大,其所致肝增大与肝脏大小本身的昼夜节律基本一致,且基本不影响生物钟相关基因的表达,提示PXR、PPARα激动可能不影响肝脏大小本身的昼夜节律。本研究阐明了PXR、PPARα激动所致肝增大的昼夜节律,为核受体促进肝增大及肝脏大小昼夜节律的研究提供新数据和参考。