基于XGBoost方法的社交网络异常用户检测技术

针对传统社交网络异常用户检测算法应用于现实中非平衡数据集时存在召回率低、运行效率低等问题,对社交网络数据集提取用户内容、行为、属性、关系特征,应用梯度增强集成分类器XGBoost算法进行特征选择,建立分类模型,构造非平衡数据集并识别三类垃圾广告发送账号。实验结果表明,该方法与随机森林等传统分类方法相比,对平衡及非平衡数据集进行异常用户检测均实现召回率和◢F▼◣▽1值的有效提升;同时其选取少量特征同样可达到较高检测水平,证明了方法的有效性。     

面向社交媒体评论的上下文语境讽刺检测模型

讽刺是日常交际中一种常见的语用现象,能够丰富说话者的观点并间接地表达说话者的深层含义。讽刺检测任务的研究目标是挖掘目标语句的讽刺倾向。针对讽刺语境表达变化多样以及不同用户、不同主题下的讽刺含义各不相同等特征,构建融合用户嵌入与论坛主题嵌入的上下文语境讽刺检测模型。该模型借助ParagraphVector方法的序列学习能力对用户评论文档与论坛主题文档进行编码,从而获取目标分类句的用户讽刺特征与主题特征,并利用一个双向门控循环单元神经网络得到目标句的语句编码。在标准讽刺检测数据集上进行的实验结果表明,与传统Bag-of-Words、CNN等模型相比,该模型能够有效提取语句的上下文语境信息,具有较高的讽刺检测分类准确率。     

基于BP网络的入侵检测方法

论文提出了一种基于BP神经网络的入侵检测方法。该方法对特征数据进行了预处理,利用改进的BP算法的学习能力和快速识别能力,实现了对用户行为的检测,尤其是在识别以前没有观察到的未知攻击方面具有较好的性能。     

基于DCNN和SVC的窃电检测北大核心

针对目前窃电检测方法存在对大规模特征分类准确率较低的问题,提出基于DCNN和SVC的窃电检测方法。从电力数据的二维角度出发,对用户的电力数据按照周数进行矩阵化,利用改进的DCNN算法对二维矩阵进行自主学习,提取特征数据并降低分类器的输入特征维数,将DCNN提取的特征数据输入到SVC分类器中,识别窃电用户。采用国家电网公开数据集建立实验模型,进一步验证方法可行性,结果表明所提方法不仅能降低输入特征维度,而且提高了窃电检测的准确率。     

基于AHP与SVM的微博机器用户检测方法

以新浪微博中的用户为研究对象,分析并提取机器用户的特征,提出一种新的微博机器用户检测方法。通过层次分析法构建分类指标体系,对各指标特征进行量化评估,利用支持向量机(SVM)算法构建机器用户检测模型。测试SVM中不同核函数对各分类指标的重要性预测,并与量化评估结果进行比对,同时测试不同核函数模型的分类精度,对比两项结果综合选择出最优分类器。实验结果表明,该方法能够对微博中的机器用户进行较为精确的检测。     

基于多传递影响力的社交媒体谣言检测方法

社交媒体谣言检测是当前研究的热点问题,现有方法多数通过获取大量用户属性学习用户特征,但不适用于谣言的早期检测,忽略了用户之间的潜在关系对信息传播的影响。提出一种基于多传递影响力的谣言检测方法,根据源微博及其对应转发(评论)之间的关系构建文本信息传播图,并通过图卷积神经网络来捕获、学习文本信息的传播特征。利用文本信息和用户传播过程中的影响力,丰富可用于谣言检测早期的检测信息。将存在转发关系的用户构成用户影响力传播图,构建一种用户节点影响力学习方法,获取用户节点影响力,以增强用户特征信息。在此基础上,将文本特征与用户特征融合以进行谣言检测,从而提升检测效果。在3个真实社交媒体数据集上的实验结果表明,该方法在谣言自动检测以及早期检测的效果都有显著提升,与目前最好的基准方法相比,在微博、Twitter15、Twitter16数据集上的正确率分别提高了2.8%、6.9%和3.4%。     

一种基于区域检测的图像检索相关反馈方法

提出一种基于用户兴趣区域检测的图像检索相关反馈学习方法,利用用户反馈为正相关的图像进行学习,进而猜测用户意图,获得更令用户满意的检索结果。该反馈学习方法的框架如下：1）对正相关的反馈图像与查询图像进行特征匹配;2）对匹配的特征使用RANSAC模型进行校准;3）进行区域选取。在选取了兴趣区域以后,可以将该区域直接抠取或将其中的特征点权值增强作为新的待查图像进行检索,提高检索的精度。实验表明本文方法可以返回更符合用户心意的检索结果。     

基于评分离散度的托攻击检测算法

检测托攻击的本质是对真实用户和虚假用户进行分类,现有的检测算法对于具有选择项的流行攻击、段攻击等攻击方式的检测鲁棒性较差。针对这一问题,通过分析真实用户和虚假用户的评分分布情况,结合ID3决策树提出基于用户评分离散度的托攻击检测Dispersion-C算法。算法通过用户评分极端评分比、去极端评分方差和用户评分标准差3个特征衡量用户评分离散度,并将其作为ID3决策树算法的分类特征,根据不同特征的信息增益选择特征作为分类属性,训练分类器。实验结果表明,Dispersion-C算法对各类托攻击均有良好的检测效果,具有较好的鲁棒性。     

基于深度学习的显著性检测方法模型——SCS

提出一种基于深度学习的图像显著性区域检测方法,该方法对2种视觉注意机制所涉及的低级对比特征和高级语义特征分别进行提取,并结合2类特征进行模型训练最终得到基于分类思想的图像显著性区域检测模型--SCS检测模型。通过对比实验得出：该方法训练得到的检测模型在检测准确度上具有显著的优势。     

基于深度学习的网络流量异常预测方法

针对网络入侵检测系统（NIDS）能够检测当前系统中存在的网络安全事件,但由于自身的高误报率和识别安全事件产生的时延,无法提前对网络安全事件进行准确率较高的预警功能,严重制约了NIDS的实际应用和未来发展的问题,提出了基于深度学习的网络流量异常预测方法。该方法提出了一种结合深度学习算法中长短期记忆网络和卷积神经网络的预测模型,能够训练得到网络流量数据的时空特征,实现预测下一时段网络流量特征变化和网络安全事件分类识别,为NIDS实现网络安全事件的预警功能提供了方法分析。实验通过使用设计好的神经网络框架对入侵检测系统流量数据集CICIDS2017进行了训练和性能测试,在该方法下流量分类的误报率下降到0.26%,总体准确率达到了99.57%,流量特征预测模型R2的最佳效果达到了0.762。     

Improving accuracy of automatic optical inspection with machine learning

Electronic devices require the printed circuit board(PCB)to support the whole structure,but the assembly of PCBs suffers from welding problem of the electronic components such as surface mounted devices(SMDs)resistors.The automated optical inspection(AOI)machine,widely used in industrial production,can take the image of PCBs and examine the welding issue.However,the AOI machine could commit false negative errors and dedicated technicians have to be employed to pick out those misjudged PCBs.This paper proposes a machine learning based method to improve the accuracy of AOI.In particular,we propose an adjacent pixel RGB value based method to pre-process the image from the AOI machine and build a customized deep learning model to classify the image.We present a practical scheme including two machine learning procedures to mitigate AOI errors.We conduct experiments with the real dataset from a production line for three months,the experimental results show that our method can reduce the rate of misjudgment from 0.3%–0.5%to 0.02%–0.03%,which is meaningful for thousands of PCBs each containing thousands of electronic components in practice.     

基于卷积神经网络的宇航电源光学检测技术

传统自动光学检测（AOI）方法难以适应宇航电源生产线多品种、小批量的特点，具有识别率低、操作复杂等问题。利用卷积神经网络(CNN)学习速度快、特征提取效果好的优势，提出了一种能够对宇航电源产品质量进行可靠检验的光学检测技术。通过对历史生产数据的精细化筛选构建了训练样本库，并设计了宇航电源产品光学检验专用卷积神经网络；将Canny算子边缘检测与CNN图像识别相结合，实现了印制板装配图信息的自动读取。与传统AOI检测方法相比，该方法缺陷识别率高达99%，且检验过程简单，提高了宇航电源产品光学检验工作效率，已应用于宇航电源生产线。     

液晶显示屏背光源模组表面缺陷自动光学检测系统设计

详细介绍了自动光学检测技术在液晶显示屏背光源模组表面缺陷在线检测中的应用,分析并比较了背光源模组缺陷自动光学在线检测中的成像技术、检测系统的组成、结构原理与设计方法,阐述了检测结果为不良品的返修方法。给出了背光源模组表面缺陷常见缺陷的种类和缺陷分类判断准则,把种类繁多的背光源模组表面缺陷分为画面缺陷、外观缺陷与异常缺陷;根据背光源模组缺陷形成的原因、种类,设计了背光源模组缺陷点灯检测和非点灯检测两种自动光学检测方案,所设计的自动光学检测方案对背光源模组组装产业开发缺陷检测系统具有有益的参考价值。     

An inspection and classification method for chip solder joints using color grads and Boolean rules

In order to improve the comprehensive performance of solder joints inspection in three aspects, i.e. high recognition rate, detailed classification of defect types and fast inspection speed, a new detection and classification algorithm of the chip solder joints based on color grads and Boolean rules is developed in this paper. Firstly, the region features, evaluation features and color grads’ features are defined and extracted based on the special solder joint image, which is acquired by a particular image acquisition system composed of a 3-CCD color digital camera and a 3-color (red, green, and blue) hemispherical LED array illumination. Secondly, the models of solder joint types are built based on extracted features and statistical characteristics of solder joint types. Thirdly, the detection and classification method is designed and presented using Boolean rules, then eight common solder joint types, including the acceptable solder joint, pseudo, no solder, lacked solder, excess solder, shifted, tombstone, and miss component, can be classified and detected by the proposed algorithm. Fourthly, the proposed algorithm is optimized to improve the inspection speed based on a parallel computing method. Finally, to evaluate the performance of the proposed method, 79 pieces of PCBs with defects were inspected by the commercial AOI system developed by the authors which integrates the proposed algorithm. Experiment and result analysis illustrates that the proposed method is better than other methods in three aspects, it can detect and classify properly all the eight common types of solder joints, its detailed classification, and high correct rate, which is up to 97.7%, are more useful to the quality control in the manufacturing process, and its inspection speed is faster, thus helping us to improve the efficiency of the manufacturing process.     

基于二值投影的PCB元件安装缺陷检测算法研究

研究分析了适用于AOI设备的PCB表面安装元件的缺陷检测算法.使用二值投影分析方法对2种元件类型的缺陷检测方法进行了研究,包括针对贴片电阻电容类型的chip元件和集成电路芯片类型的IC元件的缺陷检测方法.使用VC++6.0编写MFC程序实现算法,并制作了各种元件图像进行实验测试.实验结果表明,提出的方法能够快速有效的对两种类型的元件安装缺陷进行检测.     

An advanced auto-inspection system for micro-router collapse

In this paper, we propose an auto-optical inspection (AOI) system that can inspect micro-router (router) collapse automatically. The router is a tool used to cut a printed circuit board (PCB). A few types of defects could occur in the routers and cause unexpected damage to the PCBs. Among these defects, collapse is the most critical defect that must be detected. Currently, router manufacturing companies rely on human inspectors to control the router quality. We first extract the silhouette edges and associated features (peaks and valleys) of a router’s silhouette image by computer vision technique. Then, these silhouette edges and associated features are used to reconstruct a set of 2D isograms that correspond to the router surface. Finally, a pattern recognition method is devised to identify and classify some features of the pattern in the 2D isograms. In this study, two types of routers with different diameters are used for inspection experiments. There are 15 routers of each type. The experimental results reveal that the proposed AOI system can robustly and successfully detect the collapse of diamond-patterned routers with different sizes. The successful detection rate is above 96%. The proposed AOI system can assist in determining the quality of the routers.     

A cost-effective and automatic surface defect inspection system for hot-rolled flat steel

Defective steel brings economic and commercial reputation losses to the hot-strip manufacturers, and one of the main difficulties in using machine-vision-based technique for steel surface inspection is time taken to process the massive images suffering from uneven illumination. This paper develops a modular and cost-effective AOI system for hot-rolled flat steel in real time. Firstly, a detailed system topology is constructed according to the design goals covering the vast majority of steel mills, lighting setup and typical defect patterns are presented as well. Secondly, the image enhancement method is designed to overcome the uneven-lighting, over- or under-exposure. Thirdly, the defect detection algorithm is developed based on variance, entropy and average gradient derived from non-overlapping 32×32 pixel blocks of steel surface images. Fourthly, the proposed algorithms are implemented on FPGA in parallel to improve the inspection speed. Finally, 18,071 contiguous images (4096×1024 pixel) acquired from 7 defective steel rolls have been inspected by the realized AOI system to evaluate the performance. The experimental results show that the proposed method is speedy and effective enough for real applications in the hot-rolled steel manufacturing, with 92.11% average accuracy while 5.54% false-negative rate.     

基于机器视觉的高密度电路板缺陷检测系统

为减少高密度电路板的缺陷误报率,研究一种新型自动光学检测系统(AOI);系统采用自行研制的多色LED照明系统,利用机器视觉获取被测PCB的图像,通过图像处理软件系统快速准确地识别出各种缺陷;系统利用获取的彩色图像信息,根据各种缺陷的特征信息不同,采用OPENCV对各种缺陷的检测算法进行改进,使得系统性能有很大改进;对30块同类HDI型PCB的36300个检测点进行测试,测试结果证明,系统PCB缺陷的检出率高达99.87%,误报率只有0.32%。     

Optimal path planning for automated dimensional inspection of free-form surfaces

Structural dimensional inspection is vital for the process monitoring, quality control, and fault diagnosis in the mass production of auto bodies. Comparing with the non-contact measurement, the high-precision five-axis measuring machine with the touch-trigger probe is a preferred choice for data collection. It can assist manufacturers in making accurate inspection quickly. As the increase of free-form surfaces and diverse surface orientations in product design, existing inspection approaches cannot capture some new critical features in the curvature of products in an efficient way. Therefore, we need to develop new path planning methods for automated dimensional inspection of free-form surfaces. This paper proposes an optimal path planning system for automated programming of measuring point inspection by incorporating probe rotations and effective collision detection. Specifically, the methodological contributions include: (i) a dynamic searching volume-based algorithm is developed to detect potential collisions in the local path between measurement points; (ii) a local path generation method is proposed with the integration of the probe trajectory and the stylus rotation. Then, the inspection time matrix is proposed to quantify the measuring time of diverse local paths; (iii) an optimization approach of the global inspection path for all critical points on the product is developed to minimize the total inspection time. A case study has been conducted on an auto body to verify the performance of the proposed method. Results show that the collision-free path for the free-form auto body could be generated automatically with off-line programming, and the proposed method produces about 40% fewer dummy points and needs 32% less movement time in the auto body inspection process.     

基于MapReduce的校园网用户网购偏好分析

用户网购偏好发现是用户挖掘、电商营销以及用户个性化推荐的关键, 该文基于校园网流量, 提出了一种基于MapReduce的校园网用户网购偏好分析方法, 结合深度包检测(Deep Packet Inspection, DPI)与网络爬虫等技术, 对校园网用户网购行为进行了特征提取和识别. 以淘宝、天猫、京东三家电商网站为例, 对电商网站用户转化率进行了统计分析, 并分别对三个节假日校园网用户网购偏好进行了细致的分析.