Probe vehicle lane identification for queue length estimation at intersections

Vehicles instrumented with Global Positioning Systems, also known as GPS probe vehicles, have become increasingly popular for collecting traffic flow data. Previous studies have explored the probe vehicle data for estimating speeds and travel time; however, there is very limited research on predicting queue dynamics from such data. In this research, a methodology was developed for identifying the lane position of the GPS-instrumented vehicles when they are standing in the queue at signalized intersections with multiple lanes, particularly in the case of unequal queue. Various supervised and unsupervised clustering methods were tested on data generated from a microsimulation model. Among the tested methods, the Optimal Bayes Rule that utilizes probability density functions estimated using bivariate statistical mixture models was found to be effective in identifying the lanes. The methodology for lane identification was tested for queue length estimation. This research confirms that the lane identification is an important step required prior to the queue length estimation. The accuracies of the models for lane identification and queue length estimation were evaluated at varying levels of demand and probe vehicle market penetrations. In general, as the market penetration increases, the accuracy improves as expected. The result shows that 40% market penetration rate is adequate to reach about 90% accuracy.     

Parallel processing based on ship maneuvering in identification of interaction force coefficients

The parallel processing based on the free running model test was adopted to predict the interac-tion force coefficients (flow straightening coefficient and wake fraction) of ship maneuvering. And the multi-population genetic algorithm (MPGA) based on real coding that can contemporarily process the data of freerunning model and simulation of ship maneuvering was applied to solve the problem. Accordingly the optimalindividual was obtained using the method of genetic algorithm. The parallel processing of multi-populationsolved the prematurity in the identification for single population, meanwhile, the parallel processing of the dataof ship maneuvering (turning motion and zigzag motion) is an attempt to solve the coefficient drift problem.In order to validate the method, the interaction force coefficients were verified by the procedure and thesecoefficients measured were compared with those ones identified. The maximum error is less than 5%, and theidentification is an effective method.     

生物柴油的现状与发展趋势

为了深入了解生物柴油的发展过程和方向。介绍了生物柴油在国内外的现状和发展趋势,并在生物柴油的制备方法、原料来源和产业化状况等方面进行阐述。提出我国生物柴油发展方面的建议。     

基于高阶Prony方法的包装系统模态参数识别

包装系统可看作是多自由度系统,将该系统的暂态响应信号用Prony方法进行拟合,可求出系统各模态参数.介绍了确定系统阶数的方法,并且利用高阶Prony模型和时反信号可在噪声中准确求出各模态参数.模拟结果表明,本方法具有良好的稳健性,可用于识别包装系统的阶数和各模态参数.     

智能算法和物体斜出水水动力参数辨识

提出了一种基于智能技术的新的辨识算法一随机差分群体智能算法,并对约束物体带攻角高速出水的水动力参数进行了辨识,建立了λ22和C,的数学模型.用同一攻角的其它试验数据对辨识的模型进行了验证,结果表明,模型的预测值与观测值相当一致.     

发动机声激励下的车内高频噪声分析

为研究发动机声激励下中高频噪声和整车声学包隔声性能,在VA One软件中建立整车统计能量分析模型和声学包模型,并进行基于能量的整车隔声量测试和发动机噪声采集试验,验证了整车模型的准确性.通过对驾驶员头部声腔和腿部声腔的输入能量贡献量分析,发现前围和地板是车内噪声的主要传播路径,为后续汽车声学包的优化设计和车内噪声控制提供了帮助.     

基于曲率模态和小波变换的码头排架损伤识别方法*

为准确识别高桩码头的结构损伤,采用曲率模态、曲率模态差和小波变换法进行结构损伤识别,通过对码头排架不同损伤工况下的实例分析,验证了这3种方法在码头结构损伤识别中的可行性和适用性。研究结果表明,当结构无损模态未知时,采用曲率模态小波变换法能够较好地定位结构损伤;当结构无损模态已知时,运用曲率模态差法能准确定位结构损伤。进一步分析表明,曲率模态小波变换系数峰值和曲率模态差突变量还能用于初步判定码头结构多点损伤的损伤程度。     

基于双端口声源特性测试方法的离心泵

流体驱动机械不仅由其机壳振动而产生空气噪声,同时由于内部叶轮与流体介质和蜗壳的相互作用产生沿流体介质传递的水动力噪声.泵的水动力噪声是相连管路系统振动噪声的激励源之一,在管内安装水听器直接测试获得的水泵噪声会受到相连管系的影响.为表征水泵的水动力噪声属性,在前期研究中建立了水泵作为双端口声源的理论模型和源特性测试与参数提取分析方法,并应用于泵和阀门的双端口源特性测试.文章简要地回顾了相关研究结果,并针对离心泵测试结果进行了分析和总结.     

船舶双层底局部通风有害气体分布数值模拟研究

采用流体分析软件Fluent,对典型船舶密闭舱室双层底进行二氧化碳气体保护焊接作业时的局部通风风流流场、有害气体CO2及CO浓度场分布进行数值模拟分析,确定有害气体扩散的数学模型。通过设置组分源项的方法利用组分输运方程得出在一定通风量的情况下CO2及CO气体的浓度分布规律,并与实测数据作对比,结果基本一致,由此可根据不同通风条件下确定焊接作业危险区域,为防止CO2集聚和CO中毒采取有效措施提供理论依据。     

复杂平台下相控阵天线近场快速求解算法研究实现

提出基于高频算法的求解相控阵天线近场的快速求解方案。建立相控阵天线子阵列模型,成功应用有源单元法获取单个阵元在考虑耦合情况下的方向图特性数据。给出镜像源法在多三角面片上的射线寻径的实现方法,并成功获取了射线路径。提出基于面片的实时空间区域二分算法的射线寻径加速方法,加速射线寻径过程,提升了程序计算效能,能够快速获取较精确的相控阵天线近场。