Repeated anticipatory network traffic control using iterative optimization accounting for model bias correction

Anticipatory signal control in traffic networks adapts the signal timings with the aim of controlling the resulting (equilibrium) flows and route choice patterns in the network. This study investigates a method to support control decisions for successful applications in real traffic systems that operate repeatedly, for instance from day to day, month to month, etc. The route choice response to signal control is usually predicted through models; however this leads to suboptimality because of unavoidable prediction errors between model and reality. This paper proposes an iterative optimizing control method to drive the traffic network towards the real optimal performance by observing modeling errors and correcting for them. Theoretical analysis of this Iterative Optimizing Control with Model Bias Correction (IOCMBC) on matching properties between the modeled optimal solution and the real optimum is presented, and the advantages over conventional iterative schemes are demonstrated. A local convergence analysis is also elaborated to investigate conditions required for a convergent scheme. The main innovation is the calculation of the sensitivity (Jacobian) information of the real route choice behavior with respect to signal control variables. To avoid performing additional perturbations, we introduce a measurement-based implementation method for estimating the operational Jacobian that is associated with the reality. Numerical tests confirm the effectiveness of the proposed IOCMBC method in tackling modeling errors, as well as the influence of the optimization step size on the reality-tracking convergence.     

城市快速路区间旅行时间短期预测新算法

城市道路交通状况的预测,是实现未来路况查询、车辆动态导航等智能交通系统技术的关键。该文在分析浮动车数据的时间相关性的基础上,研究城市快速路的区间旅行时间短期预测算法。首先,采用统计方法和K-NN分类法相结合的新方法对缺失数据进行填充,并利用小波变换对每天的数据进行消噪处理;其次,在分别利用时间序列模型和人工神经网络模型对城市快速路区间旅行时间进行短期预测的基础上,通过模型组合获得预测值;最后,结合北京市区二环的一段快速路区间旅行时间的历史数据和实时数据,对该文所提出的快速路区间旅行时间短期预测算法进行了评价。结果显示,该算法的预测结果的平均绝对误差百分比控制在10.43%以内,具有良好的精度。     

简支下承式桁梁结合梁的模型试验

设计制作一个4节间下承式桁梁结合梁模型。分3个阶段10种荷载工况进行模型的力学性能试验,研究简支下承式钢桁结合梁桥的受力性能。结果表明:主桁的挠度和内力可以按平面桁架计算;桥面系中存在起控制作用的横梁,设计中应特别关注;纵梁主要受轴向拉伸和竖向弯曲作用,最大拉应力出现在每节间正中截面的下翼缘,内侧和外侧无多大区别;混凝土板的受力状态以竖向荷载作用下的弯曲为主;竖向偏载和水平偏载都不控制设计。     

砂土液化本构模型的试验研究

针对饱和砂土在动力作用下液化既有计算模型存在的问题,在汉丁-顿伊维奇(Handin-Drnevich)模型基础上,根据瞬态极限平衡理论的基本假设,按照应力状态不能逾越破坏条件等基本原则,借鉴增量非线性模型的计算思路,综合散粒体模型的优点,将整个振动液化过程划分成多个区域,并考虑液化过程中的剪胀、剪缩、刚度衰化和卸荷体缩等现象,推导出新的本构计算模型。该模型的参数少,且具有明确的物理意义,能够量化。通过室内动三轴试验对模型进行了验证。对比分析试验结果与计算结果可知,两者在孔隙水压力、应变发展初期是一致的,后期是有差异的;在应力路径方面两者的极限状态面几乎是一致的。因此,该模型可以较为完善地反映砂土液化过程中出现的各种现象。     

铁路大跨度提篮式系杆拱桥全桥模型试验

九曲河大桥是大跨度尼尔森体系钢管混凝土提篮式系杆拱桥设计方案,为了检验结构在施工及运营阶段能否满足高速铁路桥梁的功能要求,进行了该桥的全桥模型试验研究。简单介绍了模型的设计原则、相似关系和技术要点,对模型的加载方法、配重大小、测试截面设置等也进行了讨论。重点是通过对试验结果的分析以及与理论计算的比较,全面研究了结构在多种工况下的结构行为。研究表明,尼尔森体系具有受力匀称、承载能力大的特点;试验研究也验证了计算理论的正确性,同时表明该桥具有足够的横向刚度,具有较大的承受超载和偏载的能力。     

Research on Optimizing the Hidden Layer Structure of ANN-Based Model and Its Application in Predicting End-Quench Curves of Steels

IotroductionArtificialneurainetWork(ANN)isahadofinformatboProcessingsystem.ItconsistsofrnanprocessingwtwhichareWandsbolyconnectedoneanothetarerstudying,AN'NcangetinfbrmatiofromtrainjngdaaandcancoirectiyfulunthenoIiljnarmappinghominPuttooutPu.Furthrmore,theest8blishedmodelofANNcanbeusedtopredicttheinfluenceofinputparamt6rsonoutPutvaines.AN'NtechnulgyhasbeenwidelyusedinmaterialandheatndelltdisciPllnebecauseofthepropertieswttonedabove.VNaIayanatai[llusedaneurainetWorktOestirnatehottorsi…     

Biological control of harmful algal blooms: A modelling study

A multispecies dynamic simulation model (ERSEM) was used to examine the influence of allelopathic and trophic interactions causing feeding avoidance by predators, on the formation of harmful algal blooms, under environmental scenarios typical of a Mediterranean harbour (Barcelona). The biological state variables of the model included four functional groups of phytoplankton (diatoms, toxic and non-toxic flagellates and picophytoplankton), heterotrophic flagellates, micro- and mesozooplankton and bacteria. The physical–chemical forcing (irradiance, temperature and major nutrient concentrations) was based on an actual series of measurements taken along a year cycle in the Barcelona harbour. In order to evaluate potential effects of advection, some runs were repeated after introducing a biomass loss term. Numerical simulations showed that allelopathic effects of a toxic alga on a non-toxic but otherwise similar competitor did not have appreciable influence on the dynamics of the system. However, induction of avoidance of the toxic alga by predators, which resulted on increased predation pressure on other algal groups had a significant effect on the development of algal and predator populations. The presence of advection overrided the effect of these interactions and only allowed organisms with sufficiently high potential growth rates to thrive.     

高速铁路有砟轨道结构动力特性分析研究

根据我国新建高速客运专线和200 km·h-1既有线提速改造的实际情况,以有砟轨道结构为研究对象,进行轨道结构动态响应有限元建模与轨道不平顺影响的动力分析、落轴冲击数值计算和不同垫层隔振性能分析、无缝线路钢轨振动特性谐波响应分析及室内实尺模型试验,研究轨道结构动态特性.     

船舶避碰智能决策支持系统的设计与实现

建立了基于多库模式的船舶避碰智能决策支持系统(IDSSVCA)，描述了系统的总体结构，并对各个库进行简要的介绍，讨论了多库协同器的组成和作用，同时给出了系统的工作流程图，最后通过实例说明系统运行的可行性和有效性。     

Modelling high frequency force behaviour of hydraulic automotive dampers

Little information on automotive damper performance above 30 Hz is found in the published literature. Design of vehicles for low levels of noise, vibration and harshness requires attention to higher frequencies. This paper describes research into modelling damper behaviour at frequencies up to 500 Hz. The performance of a monotube damper was measured and the empirical data were used to evaluate a recently published parametric model. Methods of assessing prediction accuracy using transfer and coherence functions, and a wavelet-based transfer function were introduced. Modifications to the model were then developed to improve the prediction of high-frequency behaviour.