基于排队论的交通堵塞问题的模型选择

针对道路堵塞问题,建立了依赖状态的排队论与交通波模型.通过对数据的采集和处理,并分别运用排队论和交通波模型求出交通堵塞时车辆的排队长度,通过比较可以知道,运用排队论模型得出的车辆排队长度更符合实际情况,可以作为实际交通堵塞问题参考.     

基于Vissim对隧道车行横洞的仿真分析

为了研究中长化公路隧道内车行横道的开启状况,通过Vissim交通仿真软件,建立了交通仿真模型,然后通过在最大交通量条件下设置不同的交通比例,获得了公路隧道左右横洞的行程时间、延误以及车行横道的排队长度,并由此分析了公路隧道内车行横道的开启对隧道车辆通行的影响,从而更大程度地实现隧道车行横道的建设价值。     

城市交通大系统递阶模糊神经网络控制

利用递阶结构和模糊神经网络进行了交通系统的协调控制，其基本思想是：把交通干线作为一个大系统问题，子系统为干线上的各交叉口，用一模型神经网络在线调整各文献的绿信比；而协高器则利用测得的交通量数据用模糊神经网络方法确定干线上的信号周期和各交叉口之间的相位差，协高器和子系统的目标均为使交叉口前的平均排队长度最小，领导具研究表明提出的方法能够有效地缩小平均排队长度，从而达到减少车辆延误的目的。     

封闭型小区交通开放对城市交通的影响

随着交通需求的增加,城市交通问题日益严重,能否通过开放现有封闭型小区的道路以缓解城市交通拥堵是一个值得研究的问题.本文针对这一问题,建立了基于最短路的交通分流线性规划网络模型,提出了交通量改善因子、路段饱和度均值以及路段饱和度标准差等三个评价指标,以评价和对比封闭性小区开放前后的交通量与道路占用程度,从而反映了封闭性小区的开放对城市交通的具体影响.本文对两种不同的交通网络及交通流量数据进行了仿真与模型求解,结果表明：尽管小区开放后路网密度提高,有可能使得总交通负荷降低,但并非任何小区开放均能缓解城市交通拥堵.小区面积、位置、外部及内部道路状况等诸多因素都能影响路网的交通状态,所以,是否开放封闭型小区,需要用针对具体的小区与周边道路状况进行评估后再进行决策.     

一种数据丢包情况下的交叉口排队长度均衡控制方法

针对交通数据在传输过程中随机丢包造成交通拥堵的问题,提出一种新的交叉口排队长度均衡控制方法。考虑到交叉口交通控制的重复特性和强非线性,将无模型自适应迭代学习控制方案应用于交叉口排队长度控制中,通过实时调整各交叉口的信号配时方案来调节路口车辆的排队长度,实现各交叉口排队长度的均衡。针对道路交通网络控制中排队长度差值数据在传输过程中存在的丢包现象,将数据丢失现象描述为概率已知的伯努利序列,提出数据丢失情况下的补偿算法,即利用上次迭代的输出数据、伪梯度的估计值和控制输入差值对丢失数据进行补偿,解决存在数据丢包情况下多交叉口排队长度均衡控制问题。仿真结果表明,该方法在数据丢包的情况下迭代100次左右能够收敛于期望值并达到期望控制效果,验证了补偿算法的有效性。     

抗野值卡尔曼滤波器在排队长度预测中的应用

车辆排队长度是智能交通控制系统中最关键的交通参数之一,如何准确、有效地预测车辆的排队长度是近年来排队长度预测中研究的主要问题.为此,在利用卡尔曼滤波理论建立排队长度预测模型的基础上,针对滤波过程中较容易出现的野值问题,分析了野值对标准卡尔曼滤波的影响机理,采用了基于M估计的卡尔曼滤波野值处理方法.仿真结果表明,所提方法可有效消除野值对滤波的不利影响,提高排队长度预测的精度,具有较好的应用价值.     

拥挤路线交通量控制的模糊推理算法

当道路发生突发性事件引起交通拥挤时，一方面需要引导驾驶员转向到可替换路线， 另一方面也要对进入拥挤路线的交通量进行控制．本文通过对反映路线拥挤程度的延误时间 信息和排队长度信息进行预测，设计了在事件持续时间内，以车辆到达率不超过事件发生地 点通行能力为拥挤路线控制目标的模糊推理算法，并进行了实际案例分析．分析结果表明， 这种模糊推理算法能在一定程度上取代交通工程师们对拥挤的管理，从而提高了拥挤管理的 效率．     

双向六车道高速公路交通疏导方法研究

针对双向六车道高速公路交通事故路段,根据事故信息及对向车道通行能力与交通量等,判断车辆是否需要利用对向车道绕行。将不同的疏导策略抽象出拓扑结构图,根据不同疏导策略下的拓扑结构图及时间权值,从而可以确定最优的交通疏导策略,降低车辆因交通事故造成的时间延误。本研究针对不同的交通疏导方法建立的微观的交通疏导模型,能为高速公路应急条件下提供最优的疏导策略。     

面向动态交通分配的路段费用函数建模研究

在交通分配的研究中,车辆在路段上的行驶费用是决定网络交通流分布的关键因素之一。论文面对动态交通分配建模需要,在网络饱和条件下,对车辆在路段上的行驶时间进行了分析和建模。详细讨论了饱和交通网络中考虑容量约束下的车辆连续行驶时间和路口延误时间,在排队延迟模型中考虑了车辆的实际长度及由此而带来的影响,建立了离散的函数模型。最后给出计算实例,对比了点排队和实际排队的不同。     

基于Petri网的交通控制系统建模与评估

基于Petri网理论,提出一种对十字路口交通控制系统建模和性能评估的方法.该方法根据路口间的交通流量,计算在不同红绿灯相位差的情况下,各个路口的平均等待队列长度和平均等待时间,从而得出最优的红绿灯相位差.与通常的Petri网模型相比,该模型减少了分析的复杂性,提高了城市路网的通行能力.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate