A Robust Model Fitting-based Method for Transmission Line Extraction from Airborne LiDAR Point Cloud Data

Airborne Light Detection And Ranging(LiDAR)can provide high-quality three-dimensional information for the safety inspection of electricity corridors.However,the robust extraction of transmission lines from airborne point cloud data is still greatly challenging.Therefore,this paper proposes a robust transmission line extraction method based on model fitting from airborne point cloud data.First,the candidate power line generation method based on height information is used to reduce the computational complexity at the subsequent steps and the false positives in the extracted results.Then,on the basis of the block-and-slice-constraint Euclidean clustering,a linear structure recognition method based on RANdom SAmple Consensus(RANSAC)is proposed to produce the initial individual transmission line components.Finally,a robust nonlinear least square-based fitting method is developed for the individual transmission line to generate the parameters of its mathematical model for further optimizing the extraction.Experiments were performed on LiDAR point cloud data captured from the helicopter and Unmanned Aerial Vehicle(UAV)platform.Results indicate that the proposed method can efficiently extract the different types of transmission lines along electricity corridors,with the average precision of approximately 98.1%,the average recall of approximately 95.9%,and the average quality of approximately 94.2%,respectively.

Online-SPE-UPLC-MS/MS检测生活污水中20种毒品

对生活污水的前处理进行优化,建立了一种在线固相萃取-超高效液相色谱-串联质谱法(Online-SPE-UPLC-MS/MS)同时测定污水中20种毒品及人口标记物的方法。用金属螯合剂Na_(2)EDTA·2H_(2)O处理污水后加入同位素内标,接着用滤膜过滤后,以双柱交替模式上样。用Waters Oasis HLB固相萃取柱(2.1 mm×30 mm,20μm)进行富集浓缩后,用流动相将固相萃取柱上吸附的目标物反冲洗到Waters ACQUITY UPLC HSS T3色谱柱(2.1 mm×100 mm,1.8μm)上。柱温40℃,以乙腈-0.1%(体积分数)甲酸水溶液为流动相,采用梯度程序洗脱。采用电喷雾离子源正离子、多反应监测(MRM)模式定量检测。可替宁的线性范围在20~5000 ng·L^(-1),其余20种物质的线性范围在1~250 ng·L^(-1)之间,相关系数R2均大于0.99,检出限在0.01~0.25 ng·L^(-1)之间,加标回收率在91.57%~113.94%,精密度均小于15%。基于Online-SPE-UPLC-MS/MS建立了同时测定污水中20种毒品及人口标记物方法,该方法操作简单、灵敏高,具有良好的准确度和精密度,已成功应用于城市污水中的毒品检测,用于监测毒品滥用情况。

A Line Extraction Algorithm for Hand Drawings

This paper presents an algorithm for extracting lines from hand drawings.It starts from contour pixel tracing, fits them into contour segments, and thenextracts skeleton lines from the contour segments. The algorithm finds all con-tours in one scan of the input matrix without detecting and marking multiplepixels. In line extraction, the method Elastic Contour Segment nacing is pro-posed which extracts lines by referring to the contour segments at both sides,overcoming noise and passing through blotted areas by fitting and extrapolation.Experiments on free hand mechanical drawings, sketches, letter/numerals,as well as Chinese characters are carried out and satisfactory results are achieved.

Processing of Laser Scanner Data and Extraction of Structure Lines Using Methods of the Image Processing

激光扫描数据提供了一种新的手段用于获取高精度的数字地形表面模型。原始的航空激光扫描数据表达的是一些非规则分布的“点云” ,这些非规则分布的点需要进行有效的事后处理。这种事后处理有 2个目的 :一是将那些分布在地表面上的点 (即地面点 )与分布在非地表面上的点 (譬如树木、房屋或汽车上的点 ,即非地面点 )进行有效的分离 ;二是从分离后的地面点中提取结构线 ,用于建立高精度的数字地面模型。作者发展了一系列的基于数字形态学理论和稳健参数估计理论的方法用于分离和探测地面点。这里所介绍和开发的提取结构线的算法建立在数字图像处理和表面曲率理论的基础上。这些算法同样可以扩展地用于其他领域。所介绍的基于数字图像处理理论处理原始的航空激光扫瞄数据和提取结构线的方法取得了很好的结果。

Study on Edge Extraction Methods for Image-based Icing On-line Monitoring on Overhead Transmission Lines

A new method of measuring the icing thickness of transmission lines on-line is proposed in this paper.In this method,the pictures of transmission lines which are photoed by the camera on the iron tower are processed immediately to extract the edges of the transmission line conductor and transmission line insulators.The icing thickness can be gained by comparing the edges of the iced transmission line and the uniced one.Two icing image edge extraction methods are described in detail,that is,a method based on the combination of the wavelet transform and the floating threshold method and a method based on the combination of the optimal threshold method and the mathematical morphology transform.The icing images from the artificial climatic chamber and transmission lines are used to test the methods above.The results show that the method based on the wavelet transform and the floating threshold method does well in the extraction of relatively smooth edges,such as glaze icing on conductor and icing on the insulator;meanwhile,the method based on the optimal threshold method and the mathematical morphology transform does well in the edge extraction of icing on the conductor,especially the opaque rime icing on the conductor with complicated edges.

Determination of inorganic anions in ethyl acetate by in-line hollow fiber membrane extraction with ion chromatography

In this work, a novel hollow fiber membrane extractor was set up to extract inorganic anions from ethyl acetate using deionized water. Inorganic anions in slightly soluble organic solvents can be determined by the in-line hollow fiber membrane extractor coupled with ion chromatography at first time. Different aspects of the extraction procedure such as magnetic stirring speed, extraction flow rate and extraction time were optimized to achieve high extraction efficiency and good separation results. Satisfactory linear range, limits of detection and good repeatability were obtained. The procedure was applied to analyze inorganic anions in two commercial ethyl acetate samples.

In vitro antiproliferative and apoptosis inducing effect of a methanolic extract of Azadirachta indica oil on selected cancerous and noncancerous cell lines

Objective: To find the cytotoxic and apoptotic effects of neem oil extract on the selected cancerous(A-549, PC-3 and DU-145) and noncancerous(NIH3T3 and CCD-18Co) cell lines.Methods: Viability and cytotoxic effect induced by the extract was measured by using MTT assay and apoptotic effect of the extract was evaluated by using Hoechst 33342 and propidium iodide dual staining through a fluorescent microscope and activity of caspases 3, 8 and 9 through colorimetric assay kits. Results: The results showed that neem oil extract significantly reduced the viability in all selected cancer cells treated with varying concentrations of extract as compared with untreated cells and had less effect on noncancerous cell lines. It significantly increased the percentage of necrotic and apoptotic cells, and caspases 3, 8 and 9 activities in all cancer cells treated with extract as compared with untreated cells whereas no effect on noncancerous cell lines. It suggested that neem oil extract exerted a higher cytotoxic effect on cancer cells than normal cells and lower concentration induced apoptosis only in cancer cells.One of the apoptosis-inducing mechanism was through the activation of caspases signaling pathways. Conclusion: Conclusively, it implies that neem oil extract may contain one or more potential agents that can be used as a safe and effective anticancer therapy.

Data Pre－processing and Stroke Segment Extraction for On－line Handwritten Chinese Character Recognition

The stroke segments:' are proposed to be used as the basic features for handwritten Chinese character recognition. In this way, it is possible to overcome the difFiculties of unstable stroke information caused by stroke Joinings. The techniques of data pre-processing and stroke segment extraction have been described. In extracting stroke segment, not only the characteristics of the stroke itself, but also its absolute positions as well as relative positions with other strokes in the character have been taken into account.The primitive features for recognition were extracted under these comprehensive considerations.

Sub-pixel extraction of laser stripeand itsapplication in laser plane calibration

For calibrating the laser plane to implement 3D shape measurement, an algorithm for extracting the laser stripe with sub-pixel accuracy is proposed. The proposed algorithm mainly consists of two stages： two-side edge detection and center line extraction. First, the two-side edge of laser stripe is detected using the principal component angle-based progressive probabilistic Hough transform and its width is calculated through the distance between these two edges. Secondly, the center line of laser strip is extracted with 2D Taylor expansion at a sub-pixel level and the laser plane is calibrated with the 3D reconstructed coordinates from the extracted 2D sub-pixel ones. Experimental results demonstrate that the proposed method can not only extract the laser stripe at a high speed, nearly average 78 ms/frame, but also calibrate the coplanar laser stripes at a low error, limited to 0.3 mm. The proposed algorithm can satisfy the system requirement of two-side edge detection and center line extraction, and rapid speed, high precision, as well as strong anti-jamming.

Enhanced cytotoxic effect on human lung carcinoma cell line(A549) by gold nanoparticles synthesized from Justicia adhatoda leaf extract

Objective: To synthesize bio-inspired gold nanoparticles(AuNPs) using the leaf extract of Justicia adhatoda and evaluate the anti-cancer activity on human lung cancer cell line(A549).Methods: Synthesis of AuNPs was done using an aqueous leaf extract of Justicia adhatoda as a green route. The bio-synthesized AuNPs were confirmed and characterized by using various spectral studies such as UV-Vis spectrum, Scanning Electron Microscope with EDAX, Transmission Electron Microscope, Fourier Transmission Infrared Spectroscope analysis and Surface Enhanced Raman Spectroscopy. The cell viability was determined by MTT reduction assay. In addition, cytomorphology and the nuclear morphological study of A549 cell line was observed under fluorescence microscope. Results: UV-Vis spectrum showed surface plasmon resonance peak at 547 nm, scanning electron microscope and transmission electron microscope studies showed the monodispersed spherical shape and its average size in the range of 40.1 nm was noticed. Fourier Transmission Infrared Spectroscope analysis confirmed that the C=O group of amino acids of proteins had strong ability to bind with the surface of nanoparticle. Interestingly, our results also demonstrated inhibited proliferation of A549 cell line by MTT(IC50 value: 80 μg/mL). Cell morphology was observed and cell death was caused by apoptosis as revealed by propidium iodide staining. Conclusions: The current study proves the anticancer potential of bio-synthesized AuNPs. Thus, synthesized AuNPs can be used for the treatment of human lung cancer cell(A549) and it can be exploited for drug delivery in future.

基于自适应窗口与压缩幅值的瞬时转频估计

针对变转速工况下轴承信号的时频分布能量发散、噪声和谐波干扰强导致其转频难以获取的问题,提出一种基于自适应窗口和压缩幅值的瞬时转频估计方法。首先,通过自适应窗口在频率轴方向搜索出脊线窗口避免噪声和谐波的干扰;其次,在脊线窗口内用压缩幅值方法集中发散的脊线能量;然后,用惩罚函数法提取脊线,实现转频的精确估计;最后,根据采用轴承实验台收集的数据验证了所提出方法的有效性和鲁棒性。结果表明,相比于传统方法,采用所提方法估计瞬时转动频率使误差降低约8%。

激光点云特征与知识规则协同的车道线提取

实现车道线高效的检测提取是自动驾驶领域中亟待攻克的关键技术之一,众多基于视觉方案的检测算法由于图像数据的特点存在一定局限性,如天气光照影响成像质量、难以兼顾弯道直道等。本文结合三维激光点云优势与道路知识规则提出了一种车道线自动提取算法。首先,通过多次强化道路边界高程差异获取路面点;其次,简化Isodata算法,自适应地得到反射强度滤波阈值;然后采用随机一致性算法检测直线聚类得到候选车道,将候选车道映射成二维矢量并通过类间距约束提取正确车道线;最后,基于相邻关键特征点对的向量拓扑关系一致性实现车道线拓扑重构,得到对应现实世界中意义完整的车道线。算法在车道线达5~6条的情况下,召回率达92.46%,准确率达94.79%,综合评价指标达92.41%,实验结果证明了方法的有效性和可行性。

融合CBAM注意力机制与可变形卷积的车道线检测

为满足自动驾驶及汽车高级驾驶辅助系统(ADAS)对车道线检测准确性和实时性的要求,提出一种融合卷积块注意力机制(CBAM)与可变形卷积网络(DCN)的车道线检测方法CADCN。在特征提取模块中嵌入CBAM注意力机制,增强有用特征并抑制无用特征响应;引入可变形卷积替换常规卷积,用带偏移的采样学习车道线的几何形变,提高卷积核的建模能力;基于行锚分类思想,对行方向上的位置进行选择和分类分析,预测车道线的位置信息,提高车道线检测模型的实时性。在车道线公开数据集上对所提CADCN方法进行训练及验证,在满足实时性的情况下,CADCN方法在TuSimple数据集上准确率达到96.63%,在CULane数据集上综合评估指标F1平均值达到74.4%,验证了所提方法的有效性。

煤矿井下巷道点云变形检测及可视化研究

为解决煤矿井下巷道变形传统检测的非连续、效率低、智能化程度低的问题,提出一种深度相机与激光雷达点云融合三维空间重构后进行变形分析的新方法。设计了点云切片及提取骨骼线算法,建立了巷道变形检测模型。三维点云处理复杂,算法集成难度大,基于Qt开发了可视化变形监控软件,通过信号槽机制完成人机交互设计。测试表明,系统可对巷道全域进行自动连续检测,变形检测精度高,软件具有良好的人机交互性。

基于改进HT-LCNN线段检测模型的隧洞施工活动时间信息智能提取方法

施工活动时间信息的有效提取是隧洞施工进度分析与决策的重要前提,目前常采用的一种隧洞施工活动时间记录方式是绘制横道图线段。针对传统依赖于人工统计的方式存在效率低、易出错等问题,提出基于改进深度霍夫线条先验网络(Hough Transform-Line Convolutional Neural Network,HT-LCNN)线段检测模型的隧洞施工活动时间信息智能提取方法。首先,采用单应性变换手段进行施工日志图像预处理,解决原始图像存在的倾斜、旋转、扭曲等问题;其次,利用全局上下文注意力模块(Global Context Network,GCNet)改进HT-LCNN模型的残差模块,通过建立和共享全局注意力图,获得目标线段在特征图和通道间的长距离依赖关系,提高模型对目标手绘线段的注意力,克服原有HT-LCNN方法容易受到表格线段和文字干扰的不足,实现手绘线段的高精度智能检测;进一步地,建立施工时刻-活动坐标系,根据所检测的手绘横道图线段的端点坐标位置特征,将其自动转化为施工活动时间信息。将该方法应用于某长距离引水隧洞TBM施工日志活动时间提取,本文提出的改进HT-LCNN模型的检测精度AP_(5)、AP_(10)、AP_(15)值分别为94.7%、95.0%、95.1%,均高于HT-LCNN和LCNN;基于本文方法自动提取的施工活动时间与人工提取结果相比,平均绝对误差仅为1.82 min。本研究为隧洞施工活动时间信息准确高效提取提供了新思路。

基于点线特征融合的视觉惯性里程计方法研究

相机和惯性测量单元组成的基于图像点特征的视觉惯性里程计(Visual Inertial Odometry,VIO),广泛应用于移动机器人定位领域,但会面临点特征退化的问题,使其定位精度受到很大影响。因此,本文提出一种基于点线特征融合的VIO方法,并在EuRoC数据集上进行实验。结果表明:该方法不仅定位精度最优,而且线特征提取的时间较低。

基于神经网络特征线提取的飞机位姿识别方法研究

为实现复杂情况下的飞机位姿识别,提出了基于神经网络特征线提取的位姿识别新方法。该方法利用3D模型进行图像渲染,通过添加背景形成数据集,为提高算法鲁棒性进行了数据集增强。特征线提取模型采用卷积神经网络提取目标深度特征,利用热力图获取飞机特征线。结合飞机特征线、飞机3D模型以及n线透视方法解算目标位姿。该方法建立的飞机特征线提取模型,在复杂背景下准确率约为91%。叠加了各类噪声后,准确率为84%。飞机位姿通过EPnL算法与非线性优化进行求解。在目标背景复杂的情况下,实验得到的平均预测角度误差约为0.57°,平均预测平移误差约为0.47%。图像叠加各类噪声后,得到的平均预测角度误差约为2.11°,平均预测平移误差约为0.93%。提出的飞机位姿识别方法在复杂背景、各类噪声影响下可以较精准地预测飞机位姿,应用场景更加广泛。

时频短时集中变换方法在变工况轴承脊线提取中的应用

时变转速工况下的轴承故障诊断分析方法大多是基于主轴转速的阶次跟踪方法,但由于设计、成本等原因,转速计广泛应用受限。而基于时频脊线提取的阶次分析不依赖转速计可直接进行分析,但目前脊线提取存在提取精度较差以及提取流程效率较低等问题。据此,提出一种应用于脊线提取的短时集中变换(short-term concentrated transform, STCT)方法,首先通过一个遍历时频矩阵的向量处理时频矩阵内的数据以提高时频分辨率;其次使用新的脊线提取流程,在几乎不增加计算成本的前提下更高效、准确地完成时频脊线提取;最后通过仿真和实测信号验证该方法及流程的准确性,通过与其他时频方法的比较进一步说明所提方法的优越性,最终实现轴承时变转速工况下的故障诊断。

基于三维点云的轮对踏面轮廓动态测量教学实验设计

通过MV-DP090-02B激光轮廓传感器获取轨道车辆轮对踏面轮廓影像信息,再将物体表面轮廓位置转化为三维点云数据,并对数据进行降噪和特征提取,然后对踏面轮廓进行三维重建。文章结合轮对踏面动态测量实验,对轮对低速转动过程中的踏面轮廓进行了扫描。数据处理结果表明,基于MV-DP090-02B激光轮廓传感器获取的三维扫描点云数据及相关数据处理,可以动态测量轮对转动过程中的踏面轮廓;MV-DP090-02B激光轮廓传感器能够满足实验室的测量需求,操作简便,是“轨道交通车辆机械检修”课程实验中轮对踏面轮廓获取的一种新方法。