Efficient Deviation Detection Between a Process Model and Event Logs

Business processes described by formal or semi-formal models are realized via information systems.Event logs generated from these systems are probably not consistent with the existing models due to insufficient design of the information system or the system upgrade.By comparing an existing process model with event logs,we can detect inconsistencies called deviations,verify and extend the business process model,and accordingly improve the business process.In this paper,some abnormal activities in business processes are formally defined based on Petri nets.An efficient approach to detect deviations between the process model and event logs is proposed.Then,business process models are revised when abnormal activities exist.A clinical process in a healthcare information system is used as a case study to illustrate our work.Experimental results show the effectiveness and efficiency of the proposed approach.

An Automatic Cycle-Slip Processing Method and Its Precision Analysis

On the basis of analyzing and researching the current algorithms of cycle-slip detection and correction, a new method of cycle-slip detection and correction is put forward in this paper, that is, a reasonable cycle-slip detection condition and algorithm with corresponding program COMPRE (COMpass PRE-processing) to detect and correct cycle-slip automatically, compared with GIPSY and GAMIT software, for example, it is proved that this method is effective and credible to cycle-slip detection and correction in GPS data pre-processing.

Oil/Gas Pipeline Leak Inspection and Repair in Underwater Poor Visibility Conditions: Challenges and Perspectives

Mechanical pressure clamps are examples of innovative tools commonly used in the oil and gas industry for arresting leaks from damaged oil and gas pipelines. However, if leaks result from pipeline rupture, clamps are not usually recommended. It is therefore obvious that inspection of the leaking pipeline is very crucial in deciding the strategy for repair. For subsea pipelines where underwater poor visibility is pronounced, this important aspect of the pipeline repair process becomes difficult to implement. The result is a repair-leak-repair cycle. This challenge is commonly found in repairs of old pipelines in unclear water conditions. Old pipelines and their vulnerability to fractures that often lead to ruptures are discussed. In this paper, the challenges and technologies available for visualisation and examination in such unclear water conditions are discussed. There appears to be a gap in the existing pipeline integrity management system with respect to inspection and repair of pipelines in unclear water conditions. This gap needs to be filled in order to minimise spills and pollution. For pipelines installed in unclear water condition, a perspective is suggested to extend the capability of existing remotely operated vehicles to employ the use of clear laminar water system or a related technique to provide integrity engineers and operators with close visual assess to inspect leaking pipelines and effect adequate repairs. This paper suggests that the use of optical eye as the main tool for examination remains valuable in managing the challenges in underwater pipeline repairs in unclear water condition.

古籍文献老化因素分析检测及物理化学修补技术

针对中国古籍文献老化程度的分析研究,是对其进行科学评估和有效保护的一项重要基础工作。研究从2个方面探讨分析了古籍文献的老化因素,即纸张老化和字迹书写材料老化;并重点结合内因与外因分析影响古纸老化的原因,采用现代手段对古籍文献老化程度检测。并根据文物研究领域的发展现状和前沿动态,围绕纸张老化和字迹书写材料老化,介绍了光谱分析法和光学显微镜法2大类技术手段,用以测定古籍文献中纸张和墨迹的老化程度。解决和减缓古籍文献老化进程,重点梳理了纸质文物保护的无酸胶补修复及脱酸技术实现。

炼化企业挥发性有机化合物减排的探索与实践

炼化企业加工过程有组织、无组织排放的挥发性有机化合物(VOCs)量较大,对大气环境中的颗粒物、臭氧浓度等产生重大影响。A公司自“十三五”以来对VOCs减排进行了探索与实践,通过采取油气回收、储罐浮盘高效密封改造、呼吸阀改型升级、无组织排放改为有组织回收、VOCs焚烧、常态化泄漏检测与修复工作等多种减排措施,VOCs排放量已从2015年的4230 t下降到2022年的2157 t,降低比例达到49%,取得了显著的成效。

倾斜摄影三维模型中水域空洞的自动识别与修复

水域具有独特的光学反射特性,在倾斜摄影测量数据生成的模型中易导致空洞产生。为保证三维模型的完整性和显示效果,需要对水域空洞进行识别与修复。由于倾斜摄影模型内部存在大量独立的几何体,采用常规的三角网拓扑关系提取水域空洞轮廓线时会提取出所有几何体的边界轮廓线,导致无法准确识别水域空洞边界。针对此问题,本文提出了一种基于坐标转换和图像边缘检测获取水域空洞轮廓线的新方法:首先,根据OSGB模型中Z轴方向上是否存在三维点绘制水域空洞二值图,并对二值图像进行边缘检测获取水域空洞的二维轮廓线;再通过坐标转换获取水域空洞的三维轮廓线,对三维轮廓线进行约束构网、纹理映射,得到水域空洞的几何体并将绘制的水域几何体切割融合到不同的模型文件;最终实现水域空洞轮廓的自动识别以及水域空洞的自动修复。

石化企业“无异味工厂”建设路径与实践

“无异味工厂”建设是推进各类污染物管控向纵深拓展的重要举措。某石化企业通过实施全流程挥发性有机物(VOCs)源头减排、过程控制和末端治理,建设VOCs网格化监测系统,开展生产区域VOCs走航监测、实施精细化和差异化泄漏检测与修复(LDAR)管理等举措,使“无异味工厂”建设取得了明显成效,为石油化工企业改善区域环境空气质量、推进绿色洁净发展和保障员工身心健康提供参考。

基于多尺度双重自注意力的遥感影像变化检测

针对遥感影像地物目标尺度不一、上下文信息不足和边缘细节信息难以恢复等问题,提出一种基于多尺度双重自注意力的像素级变化检测网络(Pixel-based change detection Network,PixelNet)实现遥感影像变化检测任务。一方面,使用基于混合空洞卷积的多尺度特征金字塔提取卷积特征,并加入双重自注意力模块获取通道和空间注意力,兼顾细节和语义信息的同时增加特征感受野,进一步增加了全局上下文信息。另一方面,为了优化地物目标的边界圆滑模糊问题,通过边缘感知损失与加权对比损失的自动化联合训练,实现新的边缘修复模块。针对样本不均衡问题提出了带阈值的加权均衡采样的数据处理策略,以减轻变化像素数目远远小于未变化像素数目造成的网络训练倾斜问题。在遥感影像数据集CDD和LEVIR-CD上通过实验证明,所提像素级变化检测网络PixelNet在遥感变化检测任务上的主观视觉效果及客观评价指标优于SOTA的检测结果。在CDD数据集上检测精度达到98.0%,F1分数达到96.7%;在LEVIR-CD数据集上检测精度达到95.8%,F1分数为87.2%。该网络有效解决了遥感变化检测中样本不平衡、双时相特征上下文信息不足、边缘难例分类错误等问题。

基于对抗修复网络的输送带表面缺陷检测

针对输送带缺陷数据获取和标注困难、输送带工作场景中的不稳定因素和数据波动导致基于深度学习的输送带缺陷检测方法精度低的问题,提出了一种基于对抗修复网络的输送带表面缺陷检测模型。该模型主要由自编码器结构的生成器和马尔可夫判别器组成。在训练阶段,将模拟的输送带表面缺陷图像输入生成器,得到无模拟缺陷的重构图像,提升模型对未知缺陷的泛化能力;将原始无损输送带图像、重构图像和模拟的输送带表面缺陷图像输入马尔可夫判别器,通过残差块获得特征图,提高模型对于微小缺陷的检测能力。在检测阶段,将待测图像输入训练完的生成器得到重构图像,再通过训练完的马尔可夫判别器提取待测图像与重构图像的特征图,根据待测图像与重构图像特征图之间的均方误差和待测图像特征图最大值,计算异常分数并与设定的阈值进行比较,从而判断待测图像是否存在缺陷。实验结果表明,该模型的接收操作特征曲线下面积(ROC-AUC)达0.999,精确率-召回率曲线下面积(PR-AUC)达0.997,单张图像检测时间为13.51 ms,能准确定位不同类型缺陷位置。

Cycle-slip Detection of GPS Carrier Phase with Methodology of SA4 Multi-wavelet Transform

That cycle-slips remain undetected will significantly degrade the accuracy of the navigation solution when using carrier phase measurements in global positioning system （GPS）. In this paper, an algorithm based on length-4 symmetric/anti-symmetric （SA4） orthogonal multi-wavelet is presented to detect and identify cycle-slips in the context of the feature of the GPS zero-differential carrier phase measurements. Associated with the local singularity detection principle, cycle-slips can be detected and located precisely through the modulus maxima of the coefficients achieved by the multi-wavelet transform. Firstly, studies are focused on the feasibility of the algorithm employing the orthogonal multi-wavelet system such as Geronimo-Hardin-Massopust （GHM）, Chui-Lian （CL） and SA4. Moreover, the mathematical characterization of singularities with Lipschitz exponents is explained, the modulus maxima from wavelet to multi-wavelet domain is extended and a localization formula is provided from the modulus maxima of the coefficients to the original observation. Finally, field experiments with real receiver are presented to demonstrate the effectiveness of the proposed algorithm. Because SA4 possesses the specific nature of good multi-filter properties （GMPs）, it is superior to scalar wavelet and other orthogonal multi-wavelet candidates distinctly, and for the half-cycle slip, it also remains better detection, location ability and the equal complexity of wavelet transform.

基于BiLSTM与自注意力机制生成对抗网络的GSA防护方法

相量测量单元(phasor measurement unit,PMU)是智能电网的重要组成部分,能精准同步采集电力数据。由于PMU使用全球定位系统(global positioning system,GPS)提供时间同步参考,容易遭受GPS欺骗攻击(GPS spoofing attack,GSA),影响正常的数据采集。现有GSA防御方法的修复精度较低且需要额外的硬件成本。为了解决上述问题,提出一种基于双向长短期记忆网络与自注意力机制生成对抗网络的GSA防护方法。首先,提出一种改进的带梯度惩罚的Wasserstein生成对抗网络(Wasserstein generative adversarial network with gradient penalty,WGAN-GP)模型,重新设计原有生成器和判别器的网络架构,并在生成器和判别器中分别引入双向长短期记忆网络以及自注意力机制,提升模型的生成性能和鉴别能力。其次,基于所提出的WGAN-GP模型,构建了一种GSA防御模型,其包含攻击检测网络和数据修复网络2个模块,分别用于检测智能电网GSA和修复受损的PMU测量数据。最后,在IEEE-39总线系统中模拟GSA攻击,并在相应的数据集验证方法的有效性。结果表明,与现有方法对比,所提方法在大部分性能指标上取得了领先的性能。

Mass transfer,detection and repair technologies in micro-LED displays

Micro-light emitting diode(micro-LED)is an emerging display technology with excellent performance of high contrast,low power consumption,long lifetime,and fast response time compared with the current display(e.g.,liquid crystal and organic LED(OLED)).With technological advantages,micro-LED holds promise to be widely applied in augmented reality(AR),flexible screens,etc.and is thus regarded as the next generation of display technology.In the process flow of micro-LED,the step known as mass transfer that requires transferring millions of micro-LEDs from a growth substrate to a display plane,is one of the key challenges limiting the commercialization of micro-LED from laboratory.Worldwide academic and industrial efforts have been devoted to developing mass transfer strategies with purposes of improving yield and reducing cost.Herein we review three main categories of mass transfer technologies for micro-LED display(pick-and-place,fluid self-assembly and laser-enabled advanced placement)and the coupled detection and repair technologies after transfer.Discussions and comparisons have been provided about the underlying general principle,history,and representative parties,advantages,and disadvantages(yield/efficiency/cost)of these technologies.We further envision the application prospect of these transfer technologies and the promise of the future display of micro-LED.

强电离层环境下的北斗三频周跳探测与修复

针对强电离层环境下,周跳探测受电离层延迟和伪距多路径的影响容易造成误探的问题,提出了一种适应强电离层环境的周跳探测与修复方法,并选取了合适的伪距相位组合探测阈值。本文选用三频GFIF相位组合、MW组合以及电离层改正的无几何伪距相位组合进行周跳探测,在周跳修复阶段采用电离层改正的伪距相位组合和2个MW组合,解决了联立方程病态问题。通过采用磁暴发生当天的JFNG与XMIS测站观测数据,并在数据中加入2周内小周跳和随机周跳进行实验,结果表明,该方法在强电离层环境下能准确地实现周跳的探测和修复。

一种应用于二次平行封焊的工艺方法

实现二次平行封焊并达到气密性标准是气密性产品返修的关键。该文介绍了一种应用于二次平行封焊的工艺方法,通过对平行封焊后的气密性元器件进行激光开盖,在控制多余物产生后,利用机加工铣平壳体围框表面进行二次平行封焊。测试并分析了气密性元器件系统集成封装(SIP)模块二次平行封焊后的检漏。结果表明,细检漏率<1.01×10^(-8) Pa·m^(3)/s,粗检漏无连续气泡产生,气密性满足电子与电器元件试验方法(GJB 360B-2009)要求。根据该文介绍的工艺方法可为多余物可控的气密性元器件实现二次平行封焊提供一种有效的解决方案。

Surgical Repair and Detection of Cerebrospinal Fluid Rhinorrhea using Magnetic Resonance Cisternography and Skull Base Coronal Thin-section Computed Tomography Scan

INTRODUCTION Cerebrospinal fluid （CSF） rhinorrhea is a common condition managed by neurosurgeons. The accurate identification of the site of leak plays a key role in facilitating successful surgical repair. We reported two surgery-proven cases of CSF rhinorrhea examined by magnetic resonance （MR） cisternography （Siemens, Berlin, Germany） and skull base coronal thin-section computed tomography （CT） scan （Siemens, Berlin, Germany） before surgical treatment.

汽车发动机润滑系统的故障检测与维修

本文主要探讨了汽车发动机润滑系统的故障检测与维修方法。首先介绍了润滑系统在汽车发动机中的重要性和常见故障,然后详细介绍了故障检测的方法,包括机油压力检测、机油品质检查和润滑系统泄漏检查。最后,本文阐述了润滑系统的维修方法,包括机油泵维修、机油滤清器更换、机油管道维修和机油品质改善。通过掌握这些方法,相关人员可以有效地检测和维修汽车发动机润滑系统故障,延长发动机使用寿命,提高汽车性能。

基于机器视觉的带式输送机高精度煤流检测研究

针对现有基于机器视觉的带式输送机煤流检测方法存在的图像细节缺失、在多处断裂或断裂间距较大区域拟合效果较差的问题,基于直射斜收式激光三角测量原理,提出了一种基于机器视觉的带式输送机高精度煤流检测系统,将线激光发射器布置在带式输送机测量位置正上方并垂直照射煤堆,煤堆随带式输送机匀速运动,利用相机在斜上方实时拍摄包含激光条纹的煤堆表面图像。对煤流检测系统进行标定,包括相机内参数标定和激光平面标定,得到煤堆的高度信息;对煤流截面激光条纹图像进行处理,从提取精度、算法实时性等角度对比分析了灰度重心法和区域骨架法,根据对比结果选用区域骨架法提取激光条纹中心;针对利用图像膨胀操作进行激光条纹断裂修补拟合效果较差的问题,提出采用最小二乘法作为激光条纹断裂修补算法,相较于闭运算,最小二乘法拟合处理的平滑效果更好,精度较高;建立煤流截面积计算模型,通过计算每一帧上煤堆的横截面积,即可得出不同带速下的煤流体积。实验结果表明,当带速分别为0.25,0.5,1 m/s时,煤流检测系统误差均较小,最大误差分别为2.78%,3.61%和3.89%,验证了煤流检测系统具有较高的准确性。

Automatic Detection and Repair Recommendation for Missing Checks

Missing checks for untrusted inputs used in security-sensitive operations is one of the major causes of various vulnerabilities. Efficiently detecting and repairing missing checks are essential for prognosticating potential vulnerabilities and improving code reliability. We propose a systematic static analysis approach to detect missing checks for manipulable data used in security-sensitive operations of C/C++ programs and recommend repair references. First, customized securitysensitive operations are located by lightweight static analysis. Then, the assailability of sensitive data used in securitysensitive operations is determined via taint analysis. And, the existence and the risk degree of missing checks are assessed. Finally, the repair references for high-risk missing checks are recommended. We implemented the approach into an automated and cross-platform tool named Vanguard based on Clang/LLVM 3.6.0. Large-scale experimental evaluation on open-source projects has shown its effectiveness and efficiency. Furthermore, Vanguard has helped us uncover five known vulnerabilities and 12 new bugs.

一种LM-BP加速搜索的周跳探测与修复方法

针对传统三频周跳探测与修复方法中的不敏感、漏检以及效率较低等问题,提出一种基于莱文伯格-马夸特(LM)-反向传播(BP)神经网络加速搜索法的伪距相位组合与电离层残差组合联合周跳探测与修复方法:利用2个伪距相位组合以减少不敏感周跳数量,利用1个电离层残差组合以提高小周跳探测敏感度;在构成3个线性无关的组合观测值后,使用LM-BP加速搜索算法进行周跳探测与修复。实验结果表明,相对常规的伪距相位组合与电离层残差组合联合方法,该方法能够提高周跳探测与修复性能,可探测小至1个的周跳,探测与修复整体时效有较大提升。

炼油企业污水处理场VOCS治理技术应用与分析

近年来,石化行业VOCS治理已成为国家环保部门管控重点。因此,中国石油将旗下炼化企业VOCS治理成效列入环保重点检查和考核指标。由于炼化企业VOCS治理设计规范与相关标准出台相对较晚,炼化企业VOCS治理所运用的工艺各不相同,治理效果参差不齐。通过对某石化企业污水场VOCS治理工艺研究与分析,提出相应的改进措施及建议,为炼化企业污水场VOCS治理工艺应用提供技术支持。