道路维修施工路段交通分流信控优化模型

针对道路维修施工期间常采用的部分路面封闭施工且利用辅路进行分流的情形,探讨了交通分流信控优化模型。借助交通流波动理论,分析了施工路段及其前后车流拥挤排队及疏散特征和规律,分析了对车流进行控制需满足的约束,并分析了车流的延误计算公式。以总的车辆行驶时间最小化目标,原路径及分流路径的绿时分配及信号周期为优化参数,考虑交通分流控制的各种约束,建立了道路施工路段交通分流信控优化模型。分析了该模型属于非凸问题,因此提出了一种近似求解最优解的办法。通过一个示例对模型和求解算法进行了验证,并对一些规律性结果进行了分析。     

Optical Spatial Filter Sensor for Ground Speed

The prototype for a ground speed sensor has been designed, fabricated and evaluated. It works on the principle of optical spatial filtering and uses pulse driven light emitting diodes as a source of illumination. The sensor was tested at speeds ranging from 2 to 50 km/h, and an accuracy of 1.5 km/h was obtained with response time of 30 ms, height from ground of from 230 to 370 mm and on various road surfaces. The sensor is viewed as beneficial for use in a vehicle’s antilock braking system and will contribute to traffic safety.Presented at the International Commission of Optics Topical Meeting, Kyoto, 1994.     

卤素化学中的铈

卤素化学是聚合物工业生产中的重要组成部分,作为一种有吸引力的策略,它在活化天然气中轻链烷烃方面越来越受到重视.CeO2基催化剂在卤化氢回收方面有着令人兴奋的潜力,这使得基于卤素的小分子活化过程具有高效率.本文综述了近年来在高分子工业(聚氯乙烯、聚氨酯和聚碳酸酯)和天然气改质中轻烃活化方面应用的铈基催化剂的研究进展,讨论了铈催化剂的作用机理和面临的挑战,以期为未来催化材料的设计和应用提供帮助.     

人口老龄化与区域产业结构——基于分位数回归的实证研究

基于2005-2016年的省级面板数据,运用分位数回归实证分析了人口老龄化背景下,产业结构优化升级的影响因素.结果表明:全部样本的老年抚养比对产业结构优化升级的阻碍作用十分明显,东部对产业结构的影响不显著,中部的阻碍作用与全国趋势相反,西部的阻碍作用与全国趋势相同,具有明显的区域差异性;全部样本和东中西部的人均GDP都是正向推动产业结构合理化和高度化;全部样本和西部的政府行为对产业结构调整的抑制作用在增强,而东中部对产业结构调整的促进作用在增强;全部样本和东部的创新效率对产业结构调整有不断增强地推动作用,中部对产业结构调整的促进作用在减弱,而西部对产业结构调整的阻碍作用在增强.     

基于深度学习LSTM对交通流状态的预测

当今道路交通状态对城市管理和人们出行愈加重要,影响着人类生活的方方面面.以深圳交通为研究对象,由基础车辆数据和道路坐标构建了路网系统,从车辆速度和密度两个方面导出了交通流状态评价指数TSI.利用深度学习长短期记忆神经网络(LSTM)对车辆速度和密度两个指标进行预测,并通过对比极限学习机(ELM),时间序列(ARMA)和BP神经网络,进行仿真实验,结果表明相对于传统预测模型,所采用的LSTM网络具有更优的预测精确度和对远期预测的稳定性.最后利用预测结果计算出更能直观反映出道路交通拥堵情况的TSI指数,为人们提供了准确的交通状态预测.     

Identification of winter tires using vibration signals generated on the road surface

During the winter, traffic regulations state that automobile drivers must use winter tires on unsafe roads such as snowy expressways. The present report is concerned with the development of an automatic tire identification system that can discriminate winter tires from summer tires with high accuracy. The system detects the impact vibration signal that is specifically generated by winter tires when tread blocks with wide grooves strike the road surface during rolling. The signal is picked up by a commercially available vibration sensor. If the signal contains specified impact frequency components, the tire is judged to be a winter tire. Compared with the previous identification system, which used airborne tire/road noise, the proposed system has two advantages. First, it is unaffected by meteorological factors such as wind noise. Second, the proposed system performs well even when the target vehicle is traveling at low speed. We evaluate the performance of the system outdoors using a number of vehicles with various tires and demonstrate an overall improvement in identification accuracy for vehicles traveling at low or moderate speeds.     

生物油超临界CO_2酯化反应研究

将超临界CO2萃取与酯化反应耦合,研究了萃取酯化提质生物油过程。乙酸(AC)、丙酸(PA)和丙烯酸(AR)在超临界CO2(scCO2)条件下酯化时的平衡转化率显著高于常压酯化时的平衡转化率,表明scCO2对酯化反应具有明显的促进作用。这主要是由于生成的酯不断被萃入scCO2相。在恒温下scCO2的密度随压力升高而增大,因而酯化率随着CO2压力的升高而增加,与有机酸单独酯化时相比,混酸(AC、PA和AR)酯化后各种酸的转化率却比较接近,表明酯化过程中存在着酯交换机制。真实生物油的酯化结果表明,在80℃和28.0MPa下酯化3.0h,总酸的转化率可达86.78%。酯化后生物油的pH值从3.78提高到5.11,萃出生物油在140℃下挥发率接近100%,表明油品质量得到显著提升。     

超稠油供氢水热裂解改质降黏研究

通过超稠油水热裂解反应前后黏度、沥青质、硫质量分数等性质的变化，研究了超稠油进行水热裂解的主要影响因素及规律。结果表明，超稠油中含有一定量的硫是地层注蒸汽温度下进行水热裂解反应的前提。温度和时间对反应有很大影响。供氢剂中四氢萘对超稠油水热裂解影响最大。四氢萘供氢剂与硫酸镍催化剂复配使用对超稠油水热裂解有协同效应。水热裂解物理模拟实验表明,胜利单家寺油田超稠油通过供氢催化水热裂解降黏率可达70%以上。胶质、沥青质、硫质量分数降低，H/C原子比提高，超稠油得到一定程度的改善。     

无胀缝坡道路面板热胀屈曲的摄动解

文中分析了无胀缝坡道路面板在温度场作用下热胀屈曲的力学机制.采用正则摄动法导出了坡道路面板临界铺设温差的渐近表达式,分析了坡道与水平直道路面板临界铺设温差之间的关系,得出了坡道与水平直道路面板热胀屈曲的统一解答,并据此给出了无胀缝坡道路面的合理铺设温差.     

Perturbation solution for thermal expansion buckling of no expansion joint slope pavement plate

In this paper,the mechanical mechanism of thermal expansion buckling of no expansion joint slope pavement undergoing the action of a temperature field is analysed.By using regular perturbation method,the formula of perturbation solution for this problem is derived,the relationship between critical laying temperature difference of slope pavement and of level straight pavement is studied,and the unified solution and its.numerical results are also obtained.In terms of this research,rational laying temperature of no expansion joint slope pavement is given.