Exact and grid-free solutions to the Lighthill–Whitham–Richards traffic flow model with bounded acceleration for a class of fundamental diagrams

In this article, we propose a new exact and grid-free numerical scheme for computing solutions associated with an hybrid traffic flow model based on the Lighthill–Whitham–Richards (LWR) partial differential equation, for a class of fundamental diagrams. In this hybrid flow model, the vehicles satisfy the LWR equation whenever possible, and have a constant acceleration otherwise. We first propose a mathematical definition of the solution as a minimization problem. We use this formulation to build a grid-free solution method for this model based on the minimization of component function. We then derive these component functions analytically for triangular fundamental diagrams, which are commonly used to model traffic flow. We also show that the proposed computational method can handle fixed or moving bottlenecks. A toolbox implementation of the resulting algorithm is briefly discussed, and posted at https://dl.dropbox.com/u/1318701/Toolbox.zip.     

Can feedback from in-vehicle data recorders improve driver behavior and reduce fuel consumption?

This paper evaluates the effectiveness of feedback, based on In-Vehicle Data Recorders (IVDR), to improve driving behavior, increase driving safety, and reduce fuel consumption. We developed a framework for driving-behavior measurement, incorporating second-by-second data collected by IVDRs. IVDR units were installed in over 150 vehicles driven by more than 350 drivers for over a year. The experiment was divided into three stages. The first stage was a “blind”, control stage, with no feedback. The second stage incorporated verbal feedback given only to riskiest drivers. In the third stage all drivers received a bi-weekly written report about their driving performance. Safety events, such as braking, lateral acceleration or speeding, were recorded. Supplementary data regarding safety related events and fuel consumption were also collected. Safety incidents and fuel consumption were modeled as a function of IVDR measurement-based events, in order to identify which events best reflect safety incidents and excessive fuel consumption. Our results show that braking events best explain safety incidents, and all events together best explain fuel consumption. In addition, we found that for the riskiest drivers, feedback significantly reduced the IVDR events. Our models show that feedback can lead to a reduction of 8% in safety incidents, and 3–10% in fuel consumption, with a larger reduction obtained for large vehicles.     

欠驱动AUV水平面运动的镇定控制设计

通过对欠驱动AUV的水平面三自由度运动方程和轨迹方程的简化分析,设计了一种镇定控制律。基于全局微分同胚坐标变换将欠驱动AUV的数学模型转化为级联形式的非线性系统,并证明了原系统的镇定问题可简化为级联子系统的镇定问题。通过状态反馈控制研究得到镇定控制律,证明了控制律的收敛性,并且进行了镇定仿真实验演示。仿真结果表明控制律的有效性,能够在任意初始条件下实现镇定控制。     

基于T-S模糊模型的船舶舵减横摇H∞状态反馈控制

提出了一种新的船舶舵减摇控制器的设计方法。首先建立了船舶横摇和艏摇运动控制的Takagi-Sugeno(T-S)模糊模型,然后利用并行分布补偿(PDC)原理,得到了该系统的H∞状态反馈模糊控制器。应用李雅谱诺夫稳定性理论和线性矩阵不等式方法推导了H∞控制器的设计。仿真结果验证了所设计H∞模糊控制器能够有效地减小横摇。     

欠驱动不对称水面船舶输出反馈镇定控制

研究了一类欠驱动不对称船舶的全局一致渐近输出反馈镇定控制问题。该船舶横向上未装备驱动装置,加速度带有不可积的非完整约束条件,并且惯性参数矩阵和阻尼参数矩阵中的非对角线元素允许存在非零项。由于欠驱动船舶的速度和角速度不易测量,设计了高增益观测器估计速度状态变量。通过对系统进行坐标变换,并结合高增益观测器,根据分离原则设计了欠驱动不对称船舶的全局时变光滑输出反馈镇定律,仿真结果验证了所提方法的有效性。     

基于动态反馈线性化的海洋机器人近水面横摇减摇控制

海洋机器人在近水面低速航行时,在海浪干扰下将产生横摇运动,严重影响机器人安全性能,因此利用零航速减摇鳍系统对横摇运动加以有效控制.针对机器人非线性运动模型及零航速减摇鳍升力模型的特点,利用动态反馈线性化方法设计横摇减摇控制规律.该方法通过将原系统扩展为含有伪状态变量的新系统,实现系统线性化,解决由减摇鳍升力模型引起的系统非线性形式控制输入的问题.理论证明及仿真结果表明该横摇控制规律是稳定有效的.     

浅析整流回馈单元在港口起重设备节能改造中的作用

重点介绍通过由IGBT功率元件制成的国产整流回馈单元,将港口起重机负载下降的势能转换为三相交流电并回馈给供电网的过程。该项技术可以将起重机供电系统的功率因数提高到接近1.0,经工程实例验证其节能效果显著,可为老港区供电系统改造、新港区供电工程设计和设备选型提供参考。     

轮胎吊“油改电”后大规模推广能量回馈的可行性研究及经济效益分析

港口集装箱轮胎吊在油改电改造后为进一步节能降耗,采取模拟现场作业工况的方式,对电网的环境、能耗、流向进行深入研究。为轮胎吊安装能量回馈装置,并对轮胎吊分别进行单机测试和组网测试,对测试所得进行分析、计算,为大规模推广能量回馈及经济效益分析提供充分的数据。更为港口机械在油改电后"再生能源再利用"的研究提供可靠的论证。     

压力反馈控制液压夯拔装置冲击系统的研究

对压力反馈控制液压夯拔装置冲击系统的夯入机理进行了探讨，建立了冲击系统非线性数学模型，并对其性能进行了仿真和试验研究。提出了通过立柱阻力适时调节冲击系统的压力，可实现冲击能和冲击频率的自适应独立无级调节。