SIMULATION ANALYSIS OF INFLUENCE OF ROAD SURFACE ROUGHNESS ON TYRE DYNAMIC PERFORMANCE IN AUTOMOTIVE BRAKING

Using a nonlinear time varying tyre model, this paper simulatively analyzes the influence of road surface roughness amplitude and road spatial frequency on automobile ground adhesion ability. The result shows that with the increase of road surface roughness, the tyre adhesion ability declines, and the automotive braking distance increases. Moreover, the reliability of the nonlinear time varying tyre model in reflecting the influence of the road surface roughness is validated. It is testified that this model is an effective dynamic one in the simulation of automotive braking performance on uneven road.

Analysis of Dynamic Response of Explosive Disposal Robot to Rough Road Excitation

When the explosive disposal robot traveling over a rough road,it will shake up and down,and generates dynamic loads.Furthermore,the jolt of the explosive disposal robot will result in oscillation and large inertia forces of the explosive,and will effect the stability of the grasped explosive,even cause the explosive slipping from the claw and falling to the ground,which seriously threats the saJety of the robot and around environment.A tracked explosive dispasal robot has been developed at South Chi- na University of Technology.This paper takes the explosive disposal robot and the grasped explosive as study object.Especially fo- cuses on the response analysis of the grasped explosive when the robot traveling over a rough road.Analyzing the vibration character- istic of the explosive and the effects of the robot moving speeds on the stability of the explosive.The dynamic response of the explosive is obtained by simulation,the results show that the velocity of the robot is a sensitivity influence factor on the oscillation of grasped explosive.

The Shu Road and the Silk Road:Re-verifying the Diffusion Route of Indian Buddhism in Central China

The Shu Road is an important part of the Silk Road.As the transfer station for connecting the Maritime Silk Road with the Overland Silk Road and the starting point of the Southwestern Silk Road,Shu Yuandu Dao Route(Sichuan-India Road)-the predecessor of the Southwestern Silk Road,was the cultural exchange passage for China and its overseas neighbors before the opening of the famous Overland Silk Road.According to many archaeological findings and materials,Buddhism was introduced into the Central Plains along the Silk Road during the first century BC.Meanwhile,it was introduced into Bashu(the Sichuan Basin and its surrounding areas)along the Southwest Silk Road during the Eastern Han Dynasty(25-220)and was integrated into local cultures,which lead to the creation of the brilliant Buddhist culture and arts.

Dynamic response to road roughness on a tractor-semitrailer system with driver body model

A linear mass-spring system model of a tractor-semitrailer together withdriver body parts and sprung seat is presented. Natural frequencies of the system are calculated andresponse of components in the system to road roughness is completed by means of computer simulationand power spectral density (PSD) approach in all of road conditions and loading cases. The resultsshow that the severest situation of response of the system occurs when the road in rough conditionand vehicle unladen. The most sensitive frequency to human body parts is around 0.9 Hz, and modeltypes of a human body seem to be not significant to the response of a heavy tractor-semitrailersystem, including to the response of the driver himself.

Nonlinear dynamic analysis of interaction between vehicle and road surfaces for 5-axle heavy truck

Based on the analysis of nonlinear geometric characteristics of the suspension systems and tires, a 3D nonlinear dynamic model of a typical heavy truck is established. The impact factors of dynamic tire loads, including the dynamic load stress factors, and the maximal and the minimal vertical dynamic load factors, are used to evaluate the dynamic interaction between heavy vehicles and roads under the condition of random road surface roughness. Matlab/Simulink is used to simulate the nonlinear dynamic system and calculate the impact factors. The effects of different road surface conditions on the safety of vehicle movement and the durability of parts of a vehicle are analyzed, as well as the effects of different structural parameters and different vehicle speeds on road surfaces. The study results provide both the warning limits of road surface roughness and the limits of corresponding dynamic parameters for the 5-axle heavy truck.

Use of generated artificial road profiles in road roughness evaluation

In the evaluation of road roughness and its effects on vehicles response in terms of ride quality, loads induced on pavement, drivers＇ comfort, etc., it is very common to generate road profles based on the equation provided by ISO 8608 standard, according to which it is possible to group road surface profiles into eight different classes. However, real profiles are significantly different from the artificial ones because of the non-stationary fea- ture of the first ones and the not full capability of the ISO 8608 equation to correctly describe the frequency content of real road profiles. In this paper, the international roughness index, the frequency-weighted vertical acceleration awz according to ISO 2631, and the dynamic load index are applied both on artificial and real profiles, highlighting the different results obtained. The analysis carried out in this work has highlighted some limitation of the ISO 8608 approach in the description of performance and conditions of real pavement profiles. Furthermore, the different sensitivity of the various indices to the fitted power spectral density parameters is shown, which should be taken into account when performing analysis using artificial profiles.

The Profiling of International Roughness Index (IRI) Based on Lagrangian Method

The phenomenological equations of motion for the international roughness index (IRI) have been reviewed and discussed in terms of Lagrangian method in physics. The current paper proposes a practical, two-dimensional model for studying essentially three-dimensional, vibrating,?and?mechanical systems (vehicles). The purpose is to provide a new profiling method for IRI, which is practical in computations and compatible with traditional profiling for roughness of a road-surface. The modern technology employs elaborated sensors such as gyro sensor, Global Positioning System (GPS), magnetometer sensor,?and?accelerometer to measure high-speed longitudinal motions, resulting in time series of big-data expressed as compressed longitudinal spikes. The time series of longitudinal spikes obtained from high-speed longitudinal motions are traditionally considered as a background noise for constructing a profile. The conventional IRI is calculated from big-data of the road profile by employing statistical method, but the Lagrangian model dynamically determines the road profile. The useful concept and relation among the road-roughness function?, associated roughness index (ARI), acceleration and position are introduced and examined in the present paper. The associated roughness index (ARI) defined by the current dynamical approach is examined by applying virtual simulations which represent roughness of a road-surface. The current theoretical model supports and compensates information of interpreting a profile of IRI and elucidates physical meanings for the roughness index of a road-surface.

On the Link Between Ancient Sichuan and the Maritime Silk Road from the Perspective of Tang Poetry

Shu(now Sichuan Province in the southwest of China) was famous for silk production.Many poets of the Tang Dynasty praised the magnificence of Shu brocade and embroidery.They also meticulously recorded the good sales and popularity of Shu's mulberry silk fabrics in Jinling(now Nanjing) and Yangzhou through shipments along the Yangtze River and further to Southeast and South Asian countries.Tang poetry provides evidence for the significant role the Shu area played in the trade and commerce of the Maritime Silk Road.

基于Bluetooth传输的自行式路面平整度测量系统的设计

路面平整度是评价公路,特别是高速公路技术性能最重要的指标之一。如何对其进行快速精确的测量是当前十分重要的课题。文章设计了一套自行式路面平整度测量系统,采用全球首例整合性6轴运动处理组件MPU6050测量车体的倾斜角度,实现了路面平整度的自动获取;Bluetooth传输模块用于智能终端和车体之间进行数据的传送,实现了智能小车的远程控制以及对平整度信号的接收。研究结果表明,采用非接触式检测方法的自行式路面平整度测量系统由于其高速率、长距离、精度高等特点,必将成为路面平整度检测技术的发展方向。

城市新区极端雨洪汇流淹没特性与致灾机理调查研究——以郑州“7.20”特大暴雨(郑东新区)为例

近年来全球极端暴雨发生的可能性与不确定性提高,增加了城市遭遇特大洪涝灾害的风险。城市雨洪与河道洪水有显著差异,灾后雨洪信息快速采集与调研对认清雨洪特性与致灾机理尤显重要。本文以郑州2021年“7.20”特大暴雨为例,结合郑东新区地理与社会环境特点,采用野外调查测量、口述记录、多源数据分析、数值模拟对比相结合的方法开展了城市雨洪汇流淹没特性及致灾机理的调查研究。针对城市雨洪洪痕特征,拟定调查基本方法与适宜工作程序,根据调查区93处洪痕数据绘制了区域雨洪淹没分布图,分析了城市雨洪峰值水位分布特征及调查区汇流特性,探索了道路雨洪汇流流速及行洪道路阻力参数的确定方法。研究表明,城市雨洪地表主要泄流通道是街区道路,汇流方向受连续阻水、导水建筑与路网布局影响,雨洪淹没深度分布与下垫面条件和雨洪汇流特性有关。致灾机理研究分析表明,极端暴雨汇流远超城市排水管网泄流能力,雨洪选择阻力小的街道快速行洪,街道交汇处壅阻引起局部积水严重,这是极端暴雨致灾的直接诱因;而城市新区水系泄洪排涝关系不协调以及清障不力,导致城区河流行洪不畅,干支流异常高水位的顶托,严重降低了管网排涝功能,则是城市雨洪严重积涝致灾的深层原因。研究成果可为城市雨洪调查标准方法的建立与城市新区防洪排涝体系规划提供技术参考。

清代蜀道文献的特点及其历史文化价值

清代蜀道文献主要由行旅文献、诗歌文献及碑刻文献构成。蜀道行旅文献之多超过前代总合,多糅合日记、诗歌于一体,其中不乏有重要史料的佳作,是清代行旅文学的重要组成部分;蜀道诗歌文献浩繁庞杂,多见于清人别集稿本,作者群体庞大,其中既有名家巨擘,更多为非知名士人,具有写真纪实的风格特点,感叹自然奇险、忧患战乱与民生是其重要主题;碑刻文献主要是清代学者对蜀道沿线汉魏两宋碑石书法的史事考证、碑刻释文及转录。清代蜀道文献在反映蜀道交通历史变迁、蜀道地带生态环境及其社会风貌方面有重要的史料价值,同时也与清代川陕诸多重大历史事件息息相关。大量的清代蜀道诗不仅承载了清代士大夫艰难的人生行迹,也是山地生命体验的典型写照。

道路平整度检测多源数据高精度同步采集

随着使用年限增加,道路出现了不平整等路面损坏情况,急需一种快速、有效的道路平整度检测设备对道路进行检测。设计了一种道路平整度检测多传感器数据同步采集系统,以FPGA为控制核心,利用GPS输出的NEMA数据和高稳晶振建立高精度的时间基准,采用A/D采样的方式进行同步数据采集。为提高系统的抗干扰能力和数据采样的精度,传感器信号调理电路采用差分放大和抗混叠滤波设计。实验结果表明,该系统完成了多传感器数据高精度同步采集,时间同步精度为微秒级,能够为评价路面平整度提供高精度原始数据,具有数据采样精度高、稳定性好、抗干扰能力强、成本低等优点,已在武汉夕睿光电技术有限公司的道路检测车上得到成功应用。

基于GA-LSTM自适应卡尔曼滤波的路面不平度识别

准确、快速地识别出车辆当前行驶的路面激励信息,是实现智能底盘控制进而保证车辆平顺性的关键。针对传统路面不平度识别算法准确率低、自适应性差等问题,提出了基于遗传算法(genetic algorithm,GA)优化长短期记忆神经网络(long short-term memory networks,LSTM)自适应卡尔曼滤波的路面不平度识别算法。基于2自由度车辆悬架模型,通过灰色关联法选择LSTM神经网络的特征输入变量,并采用GA优化LSTM神经网络的模型参数以准确识别路面等级,并据此实时更新卡尔曼滤波器算法中的噪声矩阵,实现了在复杂路况下对路面不平度的自适应识别。仿真和试验研究表明,所提出的基于GA-LSTM自适应卡尔曼滤波算法能够快速准确的识别路面不平度与路面等级,与传统卡尔曼滤波算法相比,相关系数、均方根误差和最大绝对误差分别提高3.11%、37.5%和51.2%,表明所提算法对复杂工况具有很好的自适应能力。

抢险车对92m跨度复合材料桁架桥动态响应的影响

为研究大跨径桁架式纤维增强复合材料(FRP)应急抢修桥梁成桥后的动力性能,基于导梁推送施工92 m跨度的FRP桁架桥模型,编制FRP桁架桥的车桥耦合算法,研究抢险车辆的车速、质量及路面不平顺对FRP桁架桥的跨中竖向位移、竖向加速度和关键杆件轴向应力等指标的影响.结果表明:路面越不平顺,车辆对桥梁结构的冲击作用越大,且路面等级对竖向位移的影响大于对关键杆件轴向应力的影响;车速为20~50 km/h时,车速变化对冲击系数影响较小,但车速超过50 km/h时,车速的影响逐渐增大;车辆质量对桥梁各项指标动力响应的峰值曲线呈线性增大趋势.当车辆质量为2.80×10^(4)kg,车速30 km/h时,最大跨中竖向位移为167 mm,未超过抢修桥梁位移限值(L/120),表明该桥梁的设计可以满足抢险的通行要求.

高温冻结粉土-不同粗糙度混凝土接触面蠕变特性试验研究

为研究高温冻土-混凝土接触面的蠕变特性,利用自行研制的大型蠕变剪切仪,开展了-1℃条件下冻结粉土与粗糙度分别为0,0.538,0.775,1.225 mm混凝土接触面的分级加载蠕变试验。分析了分级加载条件下接触面蠕变曲线规律及接触面破坏特征,并将分级加载曲线转换为分别加载曲线,研究蠕变速率随时间变化规律,建立剪应力-稳定蠕变速率函数,从而得到接触面长期强度值,进一步建立接触面长期强度与粗糙度的函数关系,以探讨粗糙度抵抗蠕变的作用机理。结果表明:高温冻结粉土-混凝土接触面分级加载强度及剪切破坏时间与粗糙度呈线性正相关,随着粗糙度的增大,剪切破坏界面向土体内部偏移,破坏类型由接触面滑移破坏向土体内部破坏发展;通过陈氏法将分级加载曲线转换为分别加载曲线,得到的分别加载蠕变曲线具有衰减和非衰减蠕变特征;建立稳定蠕变速率与剪应力的函数关系符合arrhenius方程,从而得到接触面长期强度仅约为分级加载强度的20%,说明高温冻结粉土-混凝土接触面具有显著的流变效应;接触面长期强度随粗糙度的增大呈线性增长,接触面粗糙度由0 mm增大到1.225 mm时,长期强度可增大220%,可通过增大接触表面粗糙度的方法提高高温冻土-混凝土接触面的长期强度。

沥青道路粗糙度对径流颗粒物冲刷输出特性的影响

采用粗糙度量化沥青道路的表面特征,通过模型模拟、相关性分析等方法分析了道路表面粗糙度对降雨径流颗粒物冲刷输出特性的影响。结果表明:道路粗糙度、降雨强度是影响道路表面径流颗粒物冲刷输出过程的关键因素,道路粗糙度越低、降雨强度越大,道路表面径流颗粒物冲刷效应越强烈、场次降雨径流颗粒物累积冲刷量越大、径流颗粒物冲刷输出总体水平越高;道路粗糙度与降雨强度、径流历时共同影响径流颗粒物粒径分布,道路粗糙度为影响径流颗粒物粒径分布的主导因素,道路粗糙度越低、径流历时越长、降雨强度越大,径流中粒径不小于150μm的颗粒物体积占比越高,粒径小于75μm的颗粒物体积占比越低。

基于ReliefF-RBF的路面不平度识别算法研究

路面不平度对道路车辆行驶安全性及车辆动力学响应具有重要影响。通过将路面不平度识别与先进悬架控制结合,有望能进一步提升乘员舒适性和车辆的操纵稳定性。现有基于数据驱动的路面分类方法难以高效处理时变参数与车速,现有基于模型的路面识别算法需要已知精确车辆模型,在实际应用中面临车辆物理参数难以获得的问题。提出一种融合模型和数据驱动的路面分类算法,采用基于模型的方法反算等效路面轮廓,结合数据预处理方法,对车辆响应和反算等效路面轮廓数据进行滤波;对等效路面轮廓和响应信息进行时域频域特征计算,采用ReliefF算法进行关键特征提取,构建基于径向基函数神经网络的路面分类器,进行路面分级识别;通过仿真试验和实车试验验证了不同车辆参数和车速下所提出的算法鲁棒性。

蜀道陕南段传统聚落时空分布特征及影响因素

蜀道在中国古代交通史上具有重要地位,历史时期在政治、军事、经济、文化等方面发挥了突出作用。蜀道陕南段地理位置特殊、7条主线汇集,沿线传统聚落的形成和发展与线路密切相关。本文以历史地理学研究视角,结合文献研究、地图分析、统计分析及田野调查,梳理传统聚落的时空分布信息;对传统聚落历史职能进行类型分析,从具体线路和地理空间2个维度探究其分布特征。通过蜀道线路历史变迁及地理环境层面的归因分析,揭示了蜀道线路功能特点与历史演进及地形地貌、农业耕作条件等影响传统聚落时空分布的内在机制。

文化线路视角下陕南蜀道沿线传统聚落遗产特征及价值研究

蜀道是具有丰富历史文化积淀的文化线路遗产,其线路沟通川陕并汇聚于陕南地区,沿线传统聚落记录了蜀道的历史演变,留存了见证蜀道文化交流与传播的遗产要素。本研究运用历史地理学、田野调查、类型学分析等研究方法,梳理陕南蜀道沿线传统聚落的基本信息,从聚落选址与空间形态、街巷院落与传统建筑等有形要素层面,以及民俗民艺等无形要素层面分析聚落遗产特征,从蜀道文化与地域特征的视角挖掘其遗产价值,为后续沿线传统聚落的保护与发展提供科学依据。

粗糙路面检测链路模型研究

粗糙路面的反射特性影响路面检测系统的性能和路面气象检测的准确性,根据传统微面元模型,提出了一种多参量半球形等效仿真模型,建立了基于无线激光的粗糙路面链路传输模型。通过采用蒙特卡洛统计方法,分析了反射光在不同入射角和粗糙度情况下接收光功率的变化以及光子的分布规律。基于该模型,设计并实现了一套850 nm波长的非接触式激光路面状况检测系统,并利用该系统验证模型的准确性。仿真及实验结果均显示,随着入射光与路面法线方向夹角(入射角)的增大,接收到的光功率逐渐减小。当入射角小于15°时,粗糙度的增加与接收的光功率负相关;入射角大于15°时,随着粗糙度的增加,接收到的光功率逐渐增加,粗糙度越大,接收光功率与入射角的衰减关系越接近线性;当入射角达到60°时,接收到的光功率趋于常数。实验结果与模型仿真结果相吻合,从而验证了粗糙路面光反射等效半球形模型的有效性,且接收的回波信号信噪比不受路面粗糙度影响。