A new car-following model yielding log-normal type headways distributions

Modeling time headways between vehicles has attracted increasing interest in the traffic flow research field recently, because the corresponding statistics help to reveal the intrinsic interactions governing the vehicle dynamics. However, most previous micro-simulation models cannot yield the observed log-normal distributed headways. This paper designs a new car-following model inspired by the Galton board to reproduce the observed time-headway distributions as well as the complex traffic phenomena. The consistency between the empirical data and the simulation results indicates that this new car-following model provides a reasonable description of the car-following behaviours.

An Optimal Distribution of RSU for Improving Self-Driving Vehicle Connectivity

Self-driving and semi-self-driving cars play an important role in our daily lives.The effectiveness of these cars is based heavily on the use of their surrounding areas to collect sensitive and vital information.However,external infrastructures also play significant roles in the transmission and reception of control data,cooperative awareness messages,and caution notifications.In this case,roadside units are considered one of themost important communication peripherals.Random distribution of these infrastructures will overburden the spread of self-driving vehicles in terms of cost,bandwidth,connectivity,and radio coverage area.In this paper,a new distributed roadside unit is proposed to enhance the performance and connectivity of these cars.Therefore,this approach is based primarily on k-means to find the optimal location of each roadside unit.In addition,this approach supports dynamicmobility with a long period of connectivity for each car.Further,this system can adapt to various locations(e.g.,highways,rural areas,urban environments).The simulation results of the proposed system are reflected in its efficiency and effectively.Thus,the system can achieve a high connectivity rate with a low error rate while reducing costs.

Isomorphic Transformations of Uncertaintiesfor Incorporating EMYCIN-Style andPROSPECTOR-Style Systems intoa Distributed Expert System

In the past, expert systems exploited mainly the EMYCIN modeland the PROSPECTOR model to deal with uncertainties. In other words, a lot ofstand-alone expert systems which use these two models are available. If we can usethe Internet to couple them together, their performance will be improved throughcooperation. This is because the problem-solving ability of expert systems is greatlyimproved by the way of cooperation among different expert systems in a distributedexpert system. Cooperation between different expert systems with these two het-erogeneous uncertain reasoning models is essentially based on the transformations ofuncertainties of propositions between these two models. In this paper, we discoveredthe exactly isomorphic transformations uncertainties between uncertain reasoningmodels, as used by EMYCIN and PROSPECTOR.

AN EXPERT CONTROL SYSTEM FORPURIFICATION PROCESS

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Evaluation of the situational awareness effects for smart distribution networks under the novel design of indicator framework and hybrid weighting method

As a key application of smart grid technologies,the smart distribution network(SDN)is expected to have a high diversity of equipment and complexity of operation patterns.Situational awareness(SA),which aims to provide a critical visibility of the SDN,will enable a significant assurance for stable SDN operations.However,the lack of systematic evaluation through the three stages of perception,comprehensive,and prediction may prevent the SA technique from effectively achieving the performance necessary to monitor and respond to events in SDN.To analyze the feasibility and effectiveness of the SA technique for the SDN,a comprehensive evaluation framework with specific performance indicators and systematic weighting methods is proposed in this paper.Besides,to implement the indicator framework while addressing the key issues of human expert scoring ambiguity and the lack of data in specific SDN areas,an improved interval-based analytic hierarchy process-based subjective weighting and a multi-objective programming method-based objective weighting are developed to evaluate the SDN SA performance.In addition,a case study in a real distribution network of Tianjin,China is conducted whose outcomes verify the practicality and effectiveness of the proposed SA technique for SDN operating security.

考虑风险时空分布特征的跟驰工况行车风险预测

行车风险预测对提升智能汽车行车安全性至关重要,为此本文提出了一种跟驰工况下的行车风险预测模型(car-following risk prediction model, CRPM)。跟驰中车辆的减速能够反映驾驶人的认知风险,故根据车辆纵向加速度标注跟驰风险等级,并构建基于各向异性行车风险场的风险时空分布特征以用作CRPM的输入。CRPM通过卷积神经网络提取风险的空间分布特性,利用双向长短期记忆网络和注意力机制处理风险的时序依赖关系,最终输出跟驰风险等级。CRPM在航拍数据集AD4CHE上进行训练和测试。结果表明,CRPM具有良好的预测精度和提前预测时间,预测准确率达99.67%,在风险发生前2 s预测准确率为96.73%。

考虑群体决策差异冲突解决机制的配电站房健康状态评估方法

针对配电站房缺乏健康评估机制、运维周期设置不合理的问题,提出了一种考虑群体决策差异冲突解决机制的配电站房健康状态综合评估方法。首先,建立配电站房指标体系和专家评价框架,设计了一种新型的二元冲突测量函数来量化全局冲突。然后,使用专家评价结果的虚假度、可信度、可用度等测度指标构造专家修正因子,以改进D-S证据理论,通过聚合不同专家的评价意见来量化评价指标的权重。接着,建立改进灰色关联度-逼近理想解法(grey relation analysis-technique for order preference by similarity to an ideal solution, GRA-TOPSIS)评估模型,引入灰色关联接近度,与距离接近度融合得到综合接近度,改善TOPSIS评价判据片面性的缺陷。最后,计算每个配电站房的评价值与理想解之间的综合接近度,反映配电站房的健康状态。实验分析表明该方法能兼容专家评价之间的冲突性、差异性、不确定性,与现有方法相比评估结果更具准确性和合理性,对运维人员制定合理的检修决策具有一定的指导价值。

考虑供需优先特性的JSQ型空车调配优化模型及算法

面向铁路商品汽车运输JSQ型车辆的空车调配问题,首先总结其调配计划制定-执行流程,将站点装车重要程度、空车库存及缓冲、路局存车限制等要素抽象为出空、需空优先特性,结合路网点线能力制约,提炼JSQ型空车调配问题关键要素;其次,构建供需网络及网络流模型,给出各优先特性的参数标定条件,实现JSQ型空车调配问题的数学描述;然后,通过拉格朗日松弛将原问题松弛为最小费用最大流问题,设计基于Ford Fulkson方法及优先队列优化的Bellman Ford算法求解松弛问题;最后,基于中铁特货跨局调配数据验证模型及算法有效性、基于中铁特货历史数据完成全路规模下的压力测试,通过与商用求解器的对比,表明本文方法能够准确、高效地实现优化。

USED CARS测量对撞式扩散火焰的温度分布

介绍了用ＵＳＥＤＣＡＲＳ技术测量对撞式甲烷／空气扩散火焰前滞止区和尾流区的温度分布剖面。在滞止区富甲烷边观察到甲烷燃烧前的热解过程；尾流区温度高于滞止区温度，表明在滞止区有未完全燃烧的中间产物存在，在尾流区发现Ｃ２及ＣＨ的光谱也证明了这一点。

考虑线路能力协调利用的车流径路与配空组织优化模型

为提高铁路整体通过能力,均衡利用路网中各线路,应对愈发波动的运输市场,开展考虑线路能力协调利用的重空车流协调优化模型研究。首先,对线路能力协调利用的实现机理进行研究,在考虑流平衡约束、配空约束、线路能力约束基础上,增加考虑铁路线路能力协调利用约束,同时在优化目标中增加紧张线路的使用成本,构建考虑线路能力协调利用的重空车流组织优化模型,以实现在优化车流径路与空车调配方案的同时兼顾铁路线路的协调利用。其次,在此基础上设计拉格朗日松弛算法,对线路能力约束与能力协调性约束松弛,将原问题分解为车流径路子问题、空车调配子问题和虚拟车流量子问题,进而降低了问题求解难度。再次,通过5组算例对算法的有效性进行验证,案例结果说明,设计的拉格朗日松弛算法在求解大规模算例时效率优于商业求解软件Gurobi。最后,设计了包含36个车站56条线路的实际案例,算法求解耗时4757.7 s,运输组织综合成本为29535803元,通过对求解结果分析,与传统优化模型相比该模型优化结果在运输成本仅增加1.56%的前提下能力紧张的线路数量由17条缩减至12条,降低了29.4%,同时空车调配符合就近配空的原则。研究结果表明,该模型可以有效缓解铁路能力紧张情况,促进铁路线路能力的协调利用。

CARS在超音速燃烧研究中的应用

报道了氮、氧和水的Q支CARS谱以及氢的S(5)和S(6 )纯转动CARS的测量结果 ,并用来确定超音速燃烧火焰中的温度及氢和氧的浓度 ;用水的Q支CARS谱得到共振与非共振谱积分面积比随浓度的变化曲线。提出并发展的同时测量氢和氧的CARS谱新方法 ,为同时测量火焰温度和氢、氧浓度提供了一条途径 ,特别对不含氮的燃烧系统更具重要意义。

基于Design-expert软件的汽车挡泥板多目标优化

为了解决板料成形中起皱和拉裂的问题,以某汽车挡泥板为研究对象,基于Design-exper软件,建立了摩擦系数、压边力、拉延筋阻力系数与板料拉裂、起皱之间关系的数学模型。并利用该软件进行了多目标优化,得到了最佳的参数组合:摩擦系数为0.13,压边力为350 k N,拉延筋阻力系数为35%。通过有限元模拟和生产实践验证,证明了该方法的可行的。

飞行汽车混动系统动力电池和增程器的协调控制

城市空中交通(urban air mobility, UAM),是近期解决当前地面交通拥堵困境的有效方法。因此,研究飞行汽车典型飞行任务剖面下的动力系统工作特性至关重要。由于电池能量密度的限制以及纯电动飞行汽车的里程限制,因此使用油电混合作为飞行汽车的动力系统更为合理。总结垂直起降飞行汽车(vertical takeoff and landing, VTOL)任务剖面下混动系统运行性能的相关研究。基于MATLAB Simulink,提出一种混合动力的协调方法,其中同时考虑两种操作模式。根据实际操作条件,预设垂直起降和平飞两种工况下不同的操作模式。在此基础上,研究作为主要电源的增程器调节功率流和提高增程器工作效率的电池协调。直流母线电压由DC/DC转换器调节,有利于电池组的整体寿命,实现了充电和放电状态期间的功率共享。仿真结果表明:可以很好地控制直流母线电压,并且增程器和电池之间的功率共享遵循设计。

不同地区汽车典型总辐射量的研究

建立汽车在某地区典型总辐射量的计算方法,需要收集各地区的汽车销量、各地区辐照带的分布、各地区的年总辐射量和车辆年均暴晒的系数4个参数。根据这些参数,分别计算中美两地的典型总辐射量。

Heteroscedastic Laplace mixture of experts regression models and applications

Mixture of Experts(MoE)regression models are widely studied in statistics and machine learning for modeling heterogeneity in data for regression,clustering and classification.Laplace distribution is one of the most important statistical tools to analyze thick and tail data.Laplace Mixture of Linear Experts(LMoLE)regression models are based on the Laplace distribution which is more robust.Similar to modelling variance parameter in a homogeneous population,we propose and study a new novel class of models:heteroscedastic Laplace mixture of experts regression models to analyze the heteroscedastic data coming from a heterogeneous population in this paper.The issues of maximum likelihood estimation are addressed.In particular,Minorization-Maximization(MM)algorithm for estimating the regression parameters is developed.Properties of the estimators of the regression coefficients are evaluated through Monte Carlo simulations.Results from the analysis of two real data sets are presented.

发电车输出电缆不同敷设方式下载流情况分析

为确保发电车运行性能良好,须定期对发电车进行检测。利用模拟阻、感性负载,可以有效检测发电车的输出带载能力。试验人员在发电车带载测试中,发现发电车同相输出电缆之间存在严重分流不均的现象。文章通过改变发电车类型、容量、电缆敷设方式、电缆与发电车的连接方式等途径,最终确定电缆载流情况受电缆敷设方式的影响,并提出了改善发电车输出电缆分流不均的相关措施。

Geographical Distribution Of Chinese Car Market

Ⅰ. Brief Account of Geographical Divi-sion The formation and development of the do-mestic car market are heavily influenced by the development of geographic economic momen-tum. On the basis of the general economic

铁路货车散粒货物侧压力分布理论研究

文章以无黏着散粒货物为研究对象,基于经典库伦土压力基础理论,采用水平层分析法,分析了散粒货物在稳态条件下对铁路货车端、侧墙的侧压力分布,推导了主动、被动状态下的侧压力分布、合力及其作用点位置公式,并采用图解法得到了破裂角的显式解及每种状态的临界点,给出了货车散装货物侧压力的研究建议。

104型客车空气分配阀漏泄速率的探讨

当全车制动管系统保压1 min漏泄量大于5 kPa时,在制动保压位工作风缸漏泄量小的车辆的制动缸压强将继续上升,而工作风缸、容积室或制动缸漏泄速率超标的故障则容易被掩盖。针对以上问题,文章提出了通过制动管、副风缸、制动缸三条压强曲线的对比关系来判断漏泄点的方法。

Distributed Control System Retrofit for 200 MW Units of Thermal Power Plant

This paper introduces GKS-9000 Distributed Control System (DCS)developed by Nanjing Automation Research Institute (NARI) and its application in DCS retrofit project of indigenous 200 MW units and its feature.