灰色模型在原油管道蜡沉积速率预测中的应用

为了对原油管道内蜡沉积速率进行准确预测,基于灰色GM(1,N)模型理论和建模思路,综合考虑了管壁处剪切应力、管壁处温度梯度、管壁处蜡分子浓度梯度和原油的动力黏度4个影响因素,建立了 GM(1,5)蜡沉积速率模型,并与黄启玉蜡沉积模型进行模型精度对比.结果表明:GM(1,5)蜡沉积速率模型的平均相对误差为2.955 5％...     

一种新型防水剂的性能研究

该新型防水剂产品能从根本上解决混凝土中毛细孔吸水问题,防止混凝土结构被氯离子渗透,从而防止钢筋锈蚀。对该防水剂的性能进行测试研究,综合测试其对砂浆和混凝土相关性能的影响;率先采用英国标准评价混凝土吸水率;并比对该新型防水剂与某国外同类成熟产品的相关性能。该防水剂对混凝土和砂浆的7 d和28 d抗压强度均有良好的增益效果,在不改变工作性能的情况下,能有效改善混凝土和砂浆的抗渗能力。     

Evaluation of risk attitude in the shipping freight market under uncertainty

ABSTRACT

The main purpose of this study is to examine how market participants take risks, in other words, what their risk attitude/preference is, and how their risk attitude could be related to the shipping freight and other markets. To address them, we calibrated the risk attitude of participants in shipping freight markets from 2007 to 2013, and provided an example of the application of risk attitude. For market participants, risk attitude/preference has an important role in understanding shipping freight markets and managing risks under uncertainty. However, risk attitude is not directly observable. To achieve this, we applied a framework that consists of structural model and calibration with market data. We interpreted risk attitude and confirmed that a structural break occurred around 2008 for the calibrated risk attitude parameter. The average risk attitude of market participants tended to be more risk-averse after 2010. We conducted an additional analysis to provide an example of the application of calibrated risk attitude, using structural equation modeling to calculate a latent variable that reflected other commodity markets. We compared the risk attitude parameter and the latent variable, and clarified the relationship between the risk attitude parameter and commodity markets.     

基于GPS轨迹数据的不同交通状态下交通方式识别流程优化方法

基于GPS轨迹数据的交通调查技术能够有效弥补传统居民出行调查方式的不足，该技术在高峰拥堵时段的交通方式识别效果有待进一步研究.针对公交车和小汽车识别精度较低的问题，本文提出基于支持向量机(SVM)的流程优化方法，加入基于短时傅里叶变换 (STFT)的频域属性，利用遗传算法(GA)对SVM的惩罚系数和核参数进行联合优化，评估不同交通状态下交通方式和方式转换点的识别效果.结果表明：频域属性的加入能够有效提升交通方式识别精度，在道路畅通状态和一般拥堵状态下，交通方式和方式转换点的识别效果均较为理想；在严重拥堵状态下，机动化方式易与非机动化方式相混淆，方式转换点最大识别误差在13 min以内，相比于基于主观回忆的人工问卷调查方式仍具有参考性.     

货车移动遮断影响下的小客车驾驶行为识别

为识别山区双车道公路货车移动遮断影响下的小客车驾驶行为，通过无人机拍摄和图像 处理提取车辆轨迹数据，根据车头时距、小客车横向位置曲线斜率的阈值标准，标定小客车的跟 驰、换道和超车这3种驾驶行为类别；采用Kruskal Wallis检验和主成分分析法对小客车驾驶行为 特征参数进行筛选和降维，获取识别模型输入变量；运用网格搜索算法确定核函数最优参数组 合，建立基于支持向量机(SVM)的货车移动遮断下小客车驾驶行为识别模型。以云南省典型山区 双车道公路为例，多维度分析货车移动遮断下的小客车驾驶行为特性，并对识别模型进行训练和 测试。结果表明：货车移动遮断下小客车的行车速度比自由流条件下低约20~30 km·h-1；小客车 在山区双车道跟驰货车行驶时的平均车头时距为2.53 s，小于相关规范中规定的最小安全车头时 距，跟驰行车风险较大；基于SVM的货车移动遮断下小客车驾驶行为识别模型的识别准确率达 98.41%，具有良好的识别能力和应用前景。     

站台雨棚钢结构在锈蚀作用下的耐久性评估

考虑钢构件由锈蚀引起的几何削弱及材性退化,提出一种钢结构在锈蚀作用下的耐久性评估方法。通过引入大气腐蚀模型,采用锈蚀缺陷分析方法建立结构有限元模型,同时给出锈蚀钢材屈服应力比下降标准曲线得到结构剩余承载力准则。基于该评估方法,通过迭代计算构件的临界失重率,进而确定构件的损伤系数(耐久性指标)。结合算例阐述站台雨棚钢结构在大气均匀锈蚀作用下的耐久性评估流程。研究结果表明:站台雨棚整体结构的损伤系数随服役时间近似呈线性增长;均匀锈蚀引起的几何削弱与材性退化对结构整体的损伤系数几乎相同;该分析流程可为高铁站台雨棚在大气锈蚀作用下的耐久性评估提供参考。     

Modelling of the pavement acoustic longevity in Hong Kong through machine learning techniques

Traffic noise emission has long been a pervasive environmental and ecological problem, especially in the metropolitan cities with large-scale traffic network and high population density. Low noise road surface (LNRS) has been actively developed and applied as an effective measure to maintain the quieter environment of mobility service system. However, when LNRS is applied for noise abatement, the relationship between the acoustic performance and degradation of pavement has not been fully understood yet. To this end, this study aims to model the acoustic longevity of asphalt pavement as a function of the thickness, binder content, maximum aggregate size, and air void content of the pavement surface, as well as vehicle speed based on the long-term tyre-road noise data collected from 270 asphalt pavement sections in Hong Kong. Two machine learning techniques, namely artificial neural networks (ANN) and support vector machines (SVM), were employed and compared. It was found that both ANN and SVM could successfully model the pavement acoustic performance with acceptable model performance metrics. A case study showed that the ANN model was more aligned with the aging mechanisms of porous road surface, but the SVM model showed better training performance. The predicted acoustic deterioration rates of the porous surface case varied from −0.1 to 0.28 dB(A)/month rather than keeping a constant linear increasing trend, depending on pavement ageing periods and vehicle speed levels. The two-dimension sensitivity analysis (2D-SA) revealed the relative importance of pavement age and vehicle speed in controlling the acoustic performance.     

基于百度云AI的自动售检票系统人脸识别应用可行性分析

人脸识别作为生物识别技术的重要分支,因其非接触性特点,在身份认证方面已经获得广泛应用。百度云AI作为智能云平台已经开放轻量级人脸识别和认证的应用服务。基于该服务不需要重复研发人脸识别算法,短期即可完成“刷脸”乘车环境搭建。分析了基于百度云AI(人工智能)技术快速建立轨道交通AFC(自动售检票)系统人脸身份识别应用场景的可行性。     

降低东疆保税港周界安防系统误漏报率

周界安全防范技术能够对重要物品设施进行保护,避免出现盗窃和恶意破坏的行为。近年来随着安防行业的迅速发展以及港口周界对安防等级要求的不断提高,周界防范技术在港口的应用和需求也明显增长。本文对天津东疆保税港周界安防现状进行分析研究,提出了降低周界安防系统误漏报率的方法。