燃气发动机进气不均匀性试验研究

通过对6190直列燃气发动机进行缸内压力、瞬时转速及同步信号等的测量,对比各缸做功效果,分析各缸进气不均匀性对发动机造成的影响。试验结果表明,在小负荷时,循环变动率大,随着负荷的增加,循环变动率有所改善,从6190发动机p-V曲线上可以看出各缸做功并不均匀。最后提出改进优化建议。     

连续刚构桥0#块支架预应力预压施工方案

百色竹洲大桥连续刚构0#块采用预应力施载法进行支架施工,文章介绍了该支架预应力预压的方法和措施,分析了支架预压后的受力状况,提出了连续刚构0#块支架预应力预压施工方案。     

基于GA-LSSVR模型的路网短时交通流预测研究

目前,很多短时交通流预测方法仅利用某一路段历史数据的时间相关性或者道路上下游路段的时空相关性进行交通流预测,未充分考虑路网所有路段之间的时空相关性.提出了一种基于稀疏混合遗传算法优化的最小二乘支持向量回归(LSSVR)模型,并应用于路网短时交通流预测.该预测模型不仅可以自动优化LSSVR模型参数,而且可以从高维路网交通流数据中选择有助于交通流预测的变量子集.实验结果表明,与LSSVR模型相比,所提方法具有更好的预测能力;而且,少量时空变量被选择出来构建预测模型,极大减少了信息冗余,改进了模型可解释性.     

浙江舟山西堠门大跨悬索桥施工技术

浙江舟山西堠门大桥为主跨1650m的两跨连续分离式钢箱梁悬索桥,其施工采用了较多的新工艺、新技术。文章从大桥基础、索塔、锚碇、索鞍、锚道、主缆、钢箱梁以及其附属设施等方面,介绍了舟山西堠门大跨悬索桥的关键施工技术及工艺。     

基于支持向量机的隧道衬砌空洞机器识别方法

探地雷达是检测隧道衬砌空洞最为有效的方法之一,但检测数据的解析始终是限制其广泛应用的关键。基于支持向量机的基本理论,文章建立了一套隧道衬砌空洞探地雷达图像的机器识别方法,该方法包括图像预处理、特征提取和支持向量机识别三个步骤。首先,探地雷达图像需经过零时修正、滤波、偏移、增益等预处理以提高信噪比;其次,对图像的时域信号进行分段,在分段信号上提取方差、标准绝对偏差和四阶矩三个统计量作为图像特征;最后,利用已知数据对支持向量机模型进行训练,并用数值模拟和模型试验数据对训练好的支持向量机模型进行测试。结果表明,该方法不仅能够准确识别隧道衬砌和围岩内的空洞,还可以对空洞埋深及横向分布范围做出较准确的判断。     

Machine learning applications in activity-travel behaviour research: a review

ABSTRACT

This paper reviews the activity-travel behaviour literature that employs Machine Learning (ML) techniques for empirical analysis and modelling. Machine Learning algorithms, which attempt to build intelligence utilizing the availability of large amounts of data, have emerged as powerful tools in the fields of pattern recognition and big data analysis. These techniques have been applied in activity-travel behaviour studies since the early ’90s when Artificial Neural Networks (ANN) were employed to model mode choice decisions. AMOS, an activity-based modelling system developed in the mid-’90s, has ANN at its core to model and predict individual responses to travel demand management measures. In the dawn of 2000, ALBATROSS, a comprehensive activity-based travel demand modelling system, was proposed by Arentze and Timmermans using Decision Trees. Since then researchers have been exploring ML techniques like Support Vector Machines (SVM), Decision Trees (DT), Neural Networks (NN), Bayes Classifiers, and more recently, Ensemble Learners to model and predict activity-travel behaviour. A large number of publications over the years and an upward trend in the number of published articles over time indicate that Machine Learning is a promising tool for activity-travel behaviour analysis and prediction. This article, first of its kind in the literature, reviews these studies and explores the trends in activity-travel behaviour research that apply ML techniques. The review finds that mode choice decisions have received wide attention in the literature on ML applications. It was observed that most of the studies identify the lack of interpretability as a serious shortcoming in ML techniques. However, very few studies have attempted to improve the interpretability of the models. Further, some studies report the importance of feature engineering in ML-based studies, but very few studies adopt feature engineering before model development. Spatiotemporal transferability of models is another issue that has received minimal attention in the literature. In the end, the paper discusses possible directions for future research in the area of activity-travel behaviour modelling using ML techniques.     

基于非线性支持向量机的隧道煤与瓦斯突出危险性预测

为了有效地预测桃子垭隧道揭煤段是否存在煤与瓦斯突出危险性,文章根据煤与瓦斯突出综合假说及《防治煤与瓦斯突出规定》,确定了影响煤与瓦斯突出的9个关键因素。由于评价因子与突出危险程度之间存在着复杂的非线性映射关系,因此选择了非线性支持向量机(SVM)方法对隧道煤与瓦斯突出危险性进行预测研究。结合项目实际情况确定了各训练样本的具体参数,采用单项指标法、最优分类决策函数及MATLAB SVM Toolbox软件对选定的训练样本进行了煤与瓦斯突出危险性预测对比。通过N7和N8两个测点的预测结果表明,桃子垭隧道揭煤段存在煤与瓦斯突出危险性,必须做好相应的揭煤防突工作。     

基于改进的LS-SVM的潜水器拘束模试验分析方法

本文以最小二乘支持向量机为基础,将增量法和滑动窗口法相结合,建立适用于分析处理大样本数据的方法。采用该方法对某潜水器拘束模斜航试验和纯横荡试验进行了分析,获取了可以反映潜水器横向力、转首力矩的数学模型中的水动力系数,并利用构建的数学模型,预报多种工况下的潜水器所受到的水动力。通过比较预报结果和试验结果,证明了该方法的有效性。     

基于支持向量机的动力电池故障诊断

电池故障诊断是电池管理系统中一项十分重要的技术。针对电池故障和电池输出状态量之间不确定的关系,采用模糊逻辑可以对模糊关系进行准确描述。选用合适的隶属度函数来表示输出的电压、电流信号,用模糊数学理论表示不确定的电池故障与电池输出状态量之间的关系,生成模糊数据库,用支持向量机对数据进行训练和测试,由结果可知该方法有较高的准确性。     

一种实用新型底盘装配支撑结构的开发

底盘装配支撑应用于商用汽车底盘装配与工程机械车辆底盘装配,属于装配线附属工装设施.底盘装配支撑结构的适用性、可靠性、耐久性关系到底盘装配线的运行安全与运行效率.文章结合公司在建底盘装配线工艺验证问题整改,对底盘装配支撑结构进行优化,开发出一种适用于驱动桥桥包支撑的实用新型支撑结构.