绝缘子污秽等级的高光谱特征优化识别技术研究

为解决传统污秽检测方法对输电线路绝缘子污闪防治的局限性,采用非接触式、高分辨率的高光谱成像技术对污秽在线检测技术进行研究。为有效提取反应污秽度的光谱特征并削弱冗余与干扰信息的影响,提出一种小波包能量谱特征优化的绝缘子污秽等级识别技术。首先,对不同污秽度的绝缘子样品的光谱图像进行背景分割,提取均匀覆污区像素点光谱均值曲线;其次,对不同图像的光强均匀度差异、环境噪声进行预处理,并通过导数变换提升不同污秽等级间的可区分性。再次,对预处理后的谱线进行小波能量谱特征提取。最后,基于所提特征建立基于支持向量机(support vector machines, SVM)的污秽等级识别模型。实验结果表明,相比于采用全波段数据或PCA特征数据作为输入,基于小波能量谱特征建立的支持向量机(SVM)污秽等级识别模型对样品识别准确率达到99.8%。#$NL关键词：关高光谱成像;绝缘子污秽等级;小波包能量谱;支持向量机#$NL中图分类号：TM933     

面向无人驾驶地图更新的安全信任管理方案

地图的实时性和准确性在无人驾驶车辆导航中发挥着重要作用。基于卫星图像的数字地图能够保证地图中道路信息的准确性,但是根据相关路况信息进行实时更新时,由于车辆用户数较多且来源复杂,因此无法确保数据的安全性和可靠性。提出一种基于区块链的认证与信任管理方案。利用无证书签名技术实现车辆的匿名认证,保证车辆身份的可验证性和不可否认性。设计基于区块链的信任管理机制,通过存储在区块链上的历史信任值计算路况消息的可信度,同时将可靠的路况信息发送给地图更新服务器,根据车辆提供信息的真实与否更新车辆信誉值,实现车辆信誉的同步与更新。从计算开销、通信开销和信任管理功能等方面验证了该方案的有效性。仿真结果表明,该方案具有较高的地图更新效率和防骗能力,能够确保数据来源的安全性和可靠性,为无人驾驶车辆提供实时路况更新服务。     

结合l1/2范数与显著性约束的背景减除

传统背景减除模型在背景静止和前景对象移动较快时提取到的前景效果较好,但当背景变化或前景对象移动缓慢时容易将动态背景误判为前景或检测出的前景有较多空洞。针对传统背景减除模型在动态背景和前景对象移动缓慢条件下存在前景检测精度下降的问题,提出一种基于l_1/2范数与显著性约束的背景减除模型。将观测数据分为低秩背景、运动前景和动态干扰3类,利用l_1/2范数约束运动前景加强前景稀疏性,有效抑制动态背景对前景提取造成的干扰,提高运动前景在动态背景中的检测精度。引入视频每一帧的显著性约束,通过对每一帧图像进行低秩稀疏分解来检测移动缓慢的目标。实验结果表明,该模型对于复杂场景具有较强的适应能力,可有效去除动态背景对前景的干扰,快速检测出移动缓慢的前景对象,相比于l_1/1/2-RPCA背景减除模型的平均查全率、查准率和调和平均值分别提升了9、14和10个百分点。     

Fatigue crack growth prediction in nuclear piping using Markov chain Monte Carlo simulation

In this paper, we present and demonstrate a methodology to improve probabilistic fatigue crack growth (FCG) predictions by using the concept of Bayesian updating using Markov chain Monte Carlo simulations. The methodology is demonstrated on a cracked pipe undergoing fatigue loading. Initial estimates of the FCG rate are made using the Paris law. The prior probability distributions of the Paris law parameters are taken from the tests on specimen made of the same material as that of pipe. Measured data on crack depth over number of loading cycles are used to update the prior distribution using the Markov chain Monte Carlo. The confidence interval on the predicted FCG rate is also estimated. In actual piping placed in a plant, the measured data can be considered equivalent to the data received from in-service inspection. It is shown that the proposed methodology improves the fatigue life prediction. The number of observations used for updating is found to leave a significant effect on the accuracy of the updated prediction.     

Comparison of the identification performance of conventional FEM updating and integrated DIC

Full‐field identification methods are increasingly used to adequately identify constitutive parameters to describe the mechanical behavior of materials. This paper investigates the more recently introduced one‐step method of integrated digital image correlation (IDIC) with respect to the most commonly used two‐step method of finite element model updating (FEMU), which uses a subset‐based DIC algorithm. To make the comparison as objective as possible, both methods are implemented in the most equivalent manner and use the same FE model. Various virtual test cases are studied to assess the performance of both methods when subjected to different error sources: (1) systematic errors, (2) poor initial guesses for the constitutive parameters, (3) image noise, (4) constitutive model errors, and (5) experimental errors. Results show that, despite the mathematical similarity of both methods, IDIC produces less erroneous and more reliable results than FEMU, particularly for more challenging test cases exhibiting small displacements, complex kinematics, misalignment of the specimen, and image noise. Copyright © 2015 John Wiley & Sons, Ltd.     

关于"标准化+"战略的初步探讨

近来,"标准化+"战略甫一提出,就受到各级政府的高度关注和积极响应.为更深入地理解该战略的意义和内涵,支撑战略实施,本文围绕"标准化+"战略的背景和特点进行初步探讨.文章认为,"标准化+"战略提出的时代背景是国家治理挑战日益严峻、国家治理结构亟待调整、治理制度体系需要完善;"标准化+"战略的特点是定位改变的战略目标、系统协同的战略规划和持续改进的战略实施.政府在推进"标准化+"战略实施中有关键性作用,应做好系统规划、保障实施、培育能力等工作.     

基于背景自适应更新的车辆阴影检测算法

对基于视频的交通流量参数检测及交通路口控制方法而言,车辆检测是很关键的一步,但是由于车辆阴影的客观存在,经常会造成汽车数量的误检。本文在背景自适应更新的基础上,对阴影建立了模型并对检测算法进行了改进,以提高车辆检测精度。     

一种基于决策表的核增量式高效更新算法

引入简化决策表,结合简化二进制差别矩阵设计思想,提出一种基于决策表的核增量式高效更新算法.该算法在更新简化的二进制差别矩阵时,只需在原决策表基础上对记录进行相应的更新,不需要重复计算原决策表的二进制差别矩阵.采用边更新简化二进制差别矩阵边计算核,显著地提高了算法的效率和灵活性.新算法的时间复杂度和空间复杂度分别为O(|C||U′|)和O(|C||U′pos||U′|).最后用一个实例说明了新算法的高效性.     

??????????????????

If using the traditional algorithms of background extraction and update on the fixed-point DSP, which is memory-limited and weak at floating-point operation, the detection speed is slow and the real-time ability is poor. The algorithm initializes the background reference frame according to the hypothesis that the background pixel intensity appears in video sequence with maximum probability and the temporal relativity between two neighboring frames. In the session of background update, the algorithm updates the background reference frame by assigning different weights to the original background and the current frame and calculating the result based on shifting operation. It is successfully implemented on TMS320DM642 and results show that the algorithm can meet the real-time constraint in 25 FPS.     

基于压缩传感的背景差分方法研究

近年来国际上出现了一种新的信息获取理论——压缩传感理论（CS）,不同于传统的奈奎斯特采样定理,它指出只要信号具有稀疏性或可压缩性,就可以通过少量随机采样点来恢复原始信号。基于对CS理论基础的深入分析,提出一种运用背景差分进行运动目标检测的新方法,此方法可以显著减少信号采样点数和传输带宽,而且一定程度上了克服了由于如光照变化而造成的误检测,仿真结果证实了该文算法的可行性。