Improvement of Binocular Reconstruction Algorithm for Measuring 3D Pavement Texture Using a Single Laser Line Scanning Constraint

The dense and accurate measurement of 3D texture is helpful in evaluating the pavement function.To form dense mandatory constraints and improve matching accuracy,the traditional binocular reconstruction technology was improved threefold.First,a single moving laser line was introduced to carry out global scanning constraints on the target,which would well overcome the difficulty of installing and recognizing excessive laser lines.Second,four kinds of improved algorithms,namely,disparity replacement,superposition synthesis,subregion segmentation,and subregion segmentation centroid enhancement,were established based on different constraint mechanism.Last,the improved binocular reconstruction test device was developed to realize the dual functions of 3D texture measurement and precision self-evaluation.Results show that compared with traditional algorithms,the introduction of a single laser line scanning constraint is helpful in improving the measurement’s accuracy.Among various improved algorithms,the improvement effect of the subregion segmentation centroid enhancement method is the best.It has a good effect on both overall measurement and single pointmeasurement,which can be considered to be used in pavement function evaluation.

Preparation of Dashanzha Wan by three-dimensional printing

Objective:To use three-dimensional(3D)printing technology to prepare Dashanzha Wan.Methods:The standard formula proportion of Dashanzha Wan was used to prepare printable materials(normally called the ink)for 3D printing,and different doses and shapes of Dashanzha Wan were prepared.Then,the rheological properties,texture characteristics,scanning electron microscopy,and content of ursolic acid were evaluated.Results:Dashanzha Wan ink showed good shear thinning properties,which is very suitable for 3D printing.The printed sample had a beautiful and regular shape with high resolution.Meanwhile,ursolic acid content in 3D-printed Dashanzha Wan aligned with the ursolic acid content shown in the Pharmacopoeia of the People's Republic of China 2020.Conclusion:The 3D-printed Dashanzha Wan has a better texture,and can be shaped into various shapes according to individual needs,which would increase patients’interest when taking medicine.Moreover,3D printing of Dashanzha Wan could be easily integrated into the digital life system,enabling online customization or use at home.This study reveals that 3D printing technology is a promising method for the production of traditional Chinese medicine with personalized appearance,dosage,and texture,which is suitable for a broader population.

3D Echocardiogram Reconstruction Employing a Flip Directional Texture Pyramid

Three dimensional(3D)echocardiogram enables cardiologists to visua-lize suspicious cardiac structures in detail.In recent years,this three-dimensional echocardiogram carries important clinical value in virtual surgical simulation.However,this 3D echocardiogram involves a trade-off difficulty between accu-racy and efficient computation in clinical diagnosis.This paper presents a novel Flip Directional 3D Volume Reconstruction(FD-3DVR)method for the recon-struction of echocardiogram images.The proposed method consists of two main steps:multiplanar volumetric imaging and 3D volume reconstruction.In the crea-tion of multiplanar volumetric imaging,two-dimensional(2D)image pixels are mapped into voxels of the volumetric grid.As the obtained slices are discontin-uous,there are some missing voxels in the volume data.To restore the structural and textural information of 3D ultrasound volume,the proposed method creates a volume pyramid in parallel with theflip directional texture pyramid.Initially,the nearest neighbors of missing voxels in the multiplanar volumetric imaging are identified by 3D ANN(Approximate Nearest Neighbor)patch matching method.Furthermore,aflip directional texture pyramid is proposed and aggregated with distance in patch matching tofind out the most similar neighbors.In the recon-struction step,structural and textural information obtained from differentflip angle directions can reconstruct 3D volume well with the desired accuracy.Com-pared with existing 3D reconstruction methods,the proposed Flip Directional 3D Volume Reconstruction(FD-3DVR)method provides superior performance for the mean peak signal-to-noise ratio(40.538 for the proposed method I and 39.626 for the proposed method II).Experimental results performed on the cardi-ac datasets demonstrate the efficiency of the proposed method for the reconstruc-tion of echocardiogram images.

Texturing and evaluation of concrete pavement surface:A state-of-the-art review

Concrete pavement is accompanied by two major functional properties,namely noise emission and friction,which are closely related to pavement surface texture.While several technologies have been developed to mitigate tirepavement noise and improve driving friction by surface texturization,limited information is available to compare the advantages and disadvantages of different surface textures.In this study,a state-of-the-art and state-of-thepractice review is conducted to investigate the noise reduction and friction improvement technologies for concrete pavement surfaces.The commonly used tests for characterizing the surface texture,skid resistance,and noise emission of concrete pavement were first summarized.Then,the texturing methods for both fresh and hardened concrete pavement surfaces were discussed,and the friction,noise emission and durability performances of various surface textures were compared.It is found that the next generation concrete surface(NGCS)texture generally provides the best noise emission performance and excellent friction properties.The exposed aggregate concrete(EAC)and optimized diamond grinding textures are also promising alternatives.Lastly,the technical parameters for the application of both diamond grinding and diamond grinding&grooving textures were recommended based on the authors'research and practical experience in Germany and the US.This study offers a convenient reference to the pavement researchers and engineers who seek to quickly understand relevant knowledge and choose the most appropriate surface textures for concrete pavements.

A state-of-the-art review of asphalt pavement surface texture and its measurement techniques

To understand the research status of asphalt pavement texture,the related achievements and progress of pavement surface texture were systematically sorted out from three aspects:the characterization of pavement surface texture,the texture measurement and evaluation,and the relationship between texture and the skid resistance.Based on the statistical geometric characteristics,the spectral characteristics,the fractal characteristics and the multifractal characteristics,the characteristics of pavement texture were discussed.The test methods of pavement texture were divided into two categories:direct measurement methods and indirect measurement methods.The advantages and disadvantages of each measurement method were summarized.The effects of macro-texture and micro-texture on asphalt pavement were discussed,respectively.The relationship between texture and skid resistance was studied.This review shows that multifractal theory should be further studied from the aspect of road engineering.High-precision non-contact integrated detection technology should be further studied to meet the needs of complex testing environments.The method of finite element numerical simulation has potential for the analysis of pavement skid resistance.In addition,methods such as big data analysis,neural network,and deep learning should be studied to achieve the intelligent perception and management of the whole state of skid resistance prediction.

Investigation of surface textures deterioration on pavement skid-resistance using hysteresis friction models and numerical simulation method

Many rubber friction theories or some method combined theories and field-experiments are employed to evaluate the pavement skid-resistance deterioration due to the evolution of surface textures.However,these methods are difficult to be implemented in the analysis of situations with multi-factor coupling and some extreme conditions.This study developed a framework to evaluate the skid-resistance deterioration of asphalt pavements.In this framework,the portable laser scanning was used to create the digital worn pavement model,and a hydroplaning finite element(FE)model for these digital worn pavements was constructed to evaluate coupling effects of the texture evolution and factors of slip ratio,slip angle,velocity and water film on braking-cornering characteristics of tire.In this study,the deterioration of skid-resistance of five typical asphalt pavements due the surface texture wear was systematically investigated by this framework.Compared with previous works,this study established the rubber friction models for each digital worn pavement considering the energy hysteresis of rubber and the power spectrum density of surface texture.And the rubber friction model was used to define the interaction behaviors between the tire and corresponding wore pavements in the FE hydroplaning model,rather than using an empirical friction model or a fixed friction coefficient.

表面纹理对水泥吸波路面微波除冰性能的影响

为了增强水泥混凝土路面除冰效率,制备了吸波及疏水涂层,并在此基础上,构建了8种不同表面纹理,用于探究表面纹理、吸波材料对微波升温性能的影响。首先,以石墨为微波吸收剂,掺加纳米SiO_(2)制备了兼具疏水和吸波性能的水泥基涂层;通过机器学习改进铺砂法获得不同纹理的平均构造深度(mean texture depth,MTD);为了评估MTD对微波升温效率、均匀性的影响,采用课题组自行研发的微波除冰车进行微波升温试验;同时,测试了普通及涂层混凝土表面的接触角,进行了冰-混凝土冰黏附性剪切试验,用于评价本文所制备涂层的除冰效果。最后,为了保证本文设计涂层的抗滑性能,还进行了表面抗滑摆值测试。结果表明:不同程度纹理和吸波涂层两者耦合作用增强水泥路面的吸波升温效率,但纹理对升温均匀性有负面影响;当MTD从0.41 mm(未处理表面)提高至2.11mm时,吸波涂层试件的吸波升温效率提高1.42倍。同时,涂层也显著增强了试件表面的接触角,接触角从25.5°提升至104°,进而冰黏附强度降低。当设计厚度为1.5 mm时,在满足抗滑性的同时涂层仍具有较好的吸波性能。

坡率对半柔性路面材料灌注率及路用性能的影响

基于半柔性路面材料灌浆工艺的独特性,为探究坡率对其灌注率及路用性能的影响,采用3种不同流动度的灌浆料,在5个设计坡率下制备半柔性路面试件。通过计算和试验,系统评价了坡率对半柔性路面材料灌注率、高温稳定性、水稳定性及抗滑性能等关键指标的影响规律。结果显示,随着坡率的增加,半柔性路面材料的灌注率和水稳定性呈下降趋势,而高温稳定性则先增大后减小。坡度对半柔性路面构造深度的影响显著,坡率越大,坡底和坡顶的构造深度差异越大,抗滑性能受到不利影响。针对上述问题,研究提出了施工工艺优化措施,并通过室内试验加以验证。

基于复合分形的路面抗滑随机森林评估模型

路面抗滑性能直接影响着道路交通安全,而基于路表纹理特征的路面抗滑性能评估方法目前存在着可解释性差、准确度不高的问题.该研究使用精度为0.05 mm的便携式三维激光表面分析仪采集了185组路面纹理数据,通过动态摩擦因数测试仪获得了相应路段0~80 km/h速度范围内的路面摩擦数据,构建了综合表征路面纹理空间、横剖、深度方向复杂度的复合分形维数指标,建立了10 km/h和70 km/h速度下的路面抗滑性能随机森林评估模型.研究结果表明:复合分形维数具备独立描述纹理复杂程度的能力,但与路面动态摩擦因数之间不存在线性关系;复合分形维数对70 km/h速度下动态摩擦因数预估的准确度为0.78,可用于评价轮胎橡胶快速滑动状态下的路面抗滑性能;复合分形指标中的空间、横剖、表层、浅层、深层剖面分形特征共同影响着路面抗滑性能,在进行路面纹理形貌评价时,应从多种空间视角下进行纹理特征综合分析.

基于纹理特征的钢渣沥青路面抗滑性能测试与评价

沥青路面的抗滑性能快速下降一直是各国学者高度关注的问题。随着表面纹理逐渐磨损,沥青路面的抗滑性能也持续减弱。为了能更科学地评估和预测路面抗滑性能的衰减,有必要定量地建立起路面纹理和抗滑性能之间的关系。本研究采用了小型加速加载设备、高精度三维扫描设备以及数字图像处理来模拟路面纹理的磨损过程。本研究基于三维纹理特征系统评价了沥青路面的抗滑性能衰减。研究结果显示,英国摆值(BPN)与本研究采用的评价指标三维纹理参数(Sq、Ssk、Vmp、Vmc和Vvc)之间存在着紧密的联系。随着加载次数的增加,BPN和三维纹理参数都呈现出相同的衰减趋势。这些三维纹理参数不仅可以作为评估沥青路面抗滑性能的指标,还能精确地描绘钢渣沥青路面的微观磨损机制。本研究建立的关系将有助于预测路面的抗滑衰减情况,为钢渣沥青路面的路用性能研究提供了有力的技术支持。

沥青路面构造深度分区域平面拟合算法

针对现有沥青路面构造深度计算方法易受外界和人为因素影响的问题,该文提出基于线激光三维数据的构造深度分区域平面拟合算法。该算法对采集的路面三维高度数据矩阵进行预处理,并提出一种基于斜率的点云数据自适应滤波算法。然后进行分块、确定中心点的局部极值,最后以三点一面的平面拟合算法为核心,计算沥青路面的构造深度。试验结果表明:该算法与电动铺砂法的相关性超过94%,计算复杂度为立体拟合法的1/3,并实现了采集样本由点到面的跨越。

测量路面三维纹理的激光约束双目鲁棒算法

为提升激光约束双目重构算法测量路面三维纹理的普适性,增强算法的抗光干扰能力,解决激光约束目标在变化光照下的鲁棒提取问题,基于Faster-RCNN(faster-region based convolutional neural network)构建激光约束识别模型,提取5~1050 lux光照范围内人为构造的激光约束目标,对待测路面的约束目标开展子区域分割,进而实现子区域分割立体匹配下双目三维重构。结果表明:改进算法在1050 lux光照强度下的平均构造深度测量值与铺砂法的拟合系数为0.987,优于原激光约束双目重构算法的0.887;在5~1050 lux光照范围内,改进算法最大波动误差、平均波动误差分别为0.141、0.084 mm,较原激光约束双目重构算法分别降低70.20%和76.83%。

考虑路面摩擦性能的自动驾驶汽车安全制动策略

针对现有自动驾驶研究大多忽略路面摩擦性能的问题,制备了5种不同级配的沥青混合料车辙板试件,基于Persson表面分形摩擦理论和轮胎‒路面三维有限元模型,求解沥青路面的动摩擦系数和附着系数,表征其摩擦性能,并使用Matlab/Simulink软件建立自动驾驶汽车的动力学控制模块,根据车辆期望制动减速度和道路摩擦性能逆向反推求解轮缸的制动压力值,实现自动驾驶汽车的制动过程。使用CarSim软件和Matlab/Simulink进行联合仿真,设定了下坡制动和曲线制动工况,分析了纵向坡度、弯道半径和道路超高等影响因素对自动驾驶车辆制动效能的影响。

路面人造纹理定向设计及其抗滑性能研究

【目的】研究路面表面人造纹理与抗滑性能之间的关系。【方法】利用3D打印技术定向设计并制备不同形状的人造纹理试件(包含三角形纹理、矩形纹理和半圆形纹理3种形状和纹理高度为1、2、3、4、5 mm的5种纹理),并以4 mm高的三角形纹理设置了一组磨耗纹理试件,采用摆式摩擦试验、构造深度试验以及提取纹理顶部接触区域对各个试件的抗滑性能进行评价。【结果】2 mm高的三角形纹理和3 mm高的矩形纹理的抗滑性能最好,摆值均可达到107。在构造深度和摆值两个方面,三角形纹理和矩形纹理的抗滑性能相近,且均明显大于半圆形纹理的抗滑性能。随着磨损率的增大,摩擦接触面积增大,但纹理表面粗糙程度降低,导致抗滑性能逐渐衰减。【结论】纹理的抗滑性能主要取决于纹理的粗糙程度,而接触面积的影响相对较小。本文提供了一种定向纹理设计方法,为深入理解路面表面纹理与抗滑性能之间的关系提供借鉴与指导。

基于沥青路面纹理解构的轮胎/路面噪声预测方法研究

轮胎/路面噪声TPIN已成为城市环境噪声污染的重要组成部分,路面纹理是TPIN的重要影响因素。采用三维激光扫描技术获得路面点云数据,建立路面纹理三维模型,根据灰度共生矩阵(GLCM)、分形理论(FD)和功率谱密度理论(PSD)计算整体、宏观和微观纹理指标对路面纹理进行解构,建立基于纹理指标的TPIN线性回归和随机森林预测模型。结果表明:1)3种理论所计算的纹理指标可有效解构纹理,与TPIN有较好的相关性;2)车速在60 km/h时,TPIN与微观纹理的相关性更强,路面关键波长与噪声测试的轮胎波长有关;3)随机森林的预测精度高于单因素预测模型,最佳预测精度为R^(2)=0.9885,MSE=0.0004,预测效果较好。因此,可将路面纹理作为有效评价TPIN的方法。

沥青路表纹理特性与抗滑性能相关关系研究

为研究沥青路面宏、微观纹理特性与抗滑性能的相关关系,选择营运中的沥青道路作为研究对象,采用激光纹理扫描小车进行沥青路面宏、微观纹理的像素值测定,使用Matlab软件重构了沥青路面的三维数据模型.同时,利用摆式摩擦测定仪测量沥青路面摆值.最后,计算沥青混凝土路面纹理构造参数并分析沥青路面构造参数和路面抗滑性能指标间的相关性.研究表明:相对于路面轮廓无规则方向,路面轮廓竖直方向的评价指标与抗滑指标的相关性更强;纹理指标中,平均断面深度MPD与路面轮廓算术平均偏差Ra与路面抗滑性能具有较好的正相关关系,其中路面轮廓算术平均偏差Ra与摆值的相关性大于平均断面深度MPD与摆值的相关性.

基于MATLAB环境下的沥青道面表观纹理重构和分形特征研究

鉴于道面微观构造对于道面抗滑性能的重要性,文中选取变化关键筛孔的8条曲线,进行试样成型研究。借助纹理激光仪AMES进行表观纹理提取,运用MATLAB软件三维重构技术,并使用分形理论的盒子计数法,研究纹理参数与抗滑性能指标的相关性。研究表明,MATLAB软件重构三维模型高精度还原沥青道面的表观形貌,道面构造参数与抗滑性能之间具有良好的线性关系,可为后续预测道面长期抗滑性提供保障。

基于IGWO-XGBoost融合模型的沥青路面抗滑性能评估

为研究沥青路面抗滑性能影响因素,精确预测路面抗滑性能,本文使用Gocator 3110三维智能传感器采集沥青混合料试件表面纹理并使用摆式摩擦仪测试试件表面摩擦系数.针对三维纹理点云数据中的异常数据,提出基于径向基函数(RBF)的邻域插值算法进行数据质量提升.根据修复后的三维纹理点云数据计算出具有代表性的10类宏观纹理特征参数,并采用Pearson系数相关性分析法去除冗余因子,改进模型的输入特征,并构建基于改进灰狼优化算法(IGWO)与XGBoost融合的沥青路面抗滑性能预测模型,预测沥青路面的摩擦系数.结果表明,提出模型的预测精度优于多元线性回归模型、支持向量机回归模型以及基于网格化搜索的XGBoost模型.

基于室内磨耗试验的沥青表面纹理演化规律分析

交通量对在役路面抗滑性能衰减及纹理演化影响显著。为研究累积交通量对沥青路表纹理演化规律,采用激光轮廓测量仪采集各类型路面宏微观纹理,选择相应表征参数进行计算,并针对各纹理表征参数进行相关性分析,排除多重线性关系后,选取RMPD、Rsk、Rku以及RSBI作为评价路面抗滑性能指标;以课题组自主研发调试的轮胎-路面动态摩擦测试系统(tire-pavement dynamic friction analyzer,TDFA)为依托模拟不同交通量;利用TDFA进行磨耗试验,对不同交通量下路表纹理参数的演变。研究结果表明:纹理参数在交通磨耗作用下,重载交通出现区间越早,对沥青路面的磨损越严重;中后期出现重载交通则对沥青路面的抗滑性能影响相对较小。

复杂机场道面外来异物高精度实时检测算法

机场道面外来物(foreign object debris,FOD)具有类型多样、形状各异、背景复杂、目标弱小等特点,并且严重影响飞行器安全,故其高精度实时检测具有重要意义。针对以上问题,提出基于超分辨率特征金字塔并带有纹理信息提取模块的FOD实时检测网络(FOD real-time detection network,FOD-RDN)。该网络采用Darknet-53作为主干网提取特征,通过超分辨率特征金字塔对形状各异的小目标进行检测,并设计了纹理信息提取模块降低复杂背景的干扰。同时采用双通道YOLO检测器和基于CIoU的损失函数,进一步提升网络对FOD的检测精度和速度。实验结果表明,本文算法在满足实时性要求的情况下,在FOD数据集上整体检测精度达到了91.8%,相比于主流目标检测网络在FOD目标检测方面具有更好的检测效果。