装有传感器,执行器和电子控制单元(ECU)的现代车辆可以分为几个称为功能工作组(FWGS)的操作子系统。这些FWG的示例包括发动机系统,变速箱,燃油系统,制动器等。每个FWG都有相关的传感器通道,可以衡量车辆操作条件。这种丰富的数据环境有利于预测维护(PDM)技术的开发。削弱各种PDM技术的是需要强大的异常检测模型,该模型可以识别出明显偏离大多数数据的事件或观察结果,并且不符合正常车辆操作行为的明确定义的概念。在本文中,我们介绍了车辆性能,可靠性和操作(VEPRO)数据集,并使用它来创建一种基于多阶段的异常检测方法。利用时间卷积网络(TCN),我们的异常检测系统可以达到96%的检测准确性,并准确预测91%的真实异常。当利用来自多个FWG的传感器通道时,我们的异常检测系统的性能会改善。
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Time series anomaly detection has applications in a wide range of research fields and applications, including manufacturing and healthcare. The presence of anomalies can indicate novel or unexpected events, such as production faults, system defects, or heart fluttering, and is therefore of particular interest. The large size and complex patterns of time series have led researchers to develop specialised deep learning models for detecting anomalous patterns. This survey focuses on providing structured and comprehensive state-of-the-art time series anomaly detection models through the use of deep learning. It providing a taxonomy based on the factors that divide anomaly detection models into different categories. Aside from describing the basic anomaly detection technique for each category, the advantages and limitations are also discussed. Furthermore, this study includes examples of deep anomaly detection in time series across various application domains in recent years. It finally summarises open issues in research and challenges faced while adopting deep anomaly detection models.
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现代高性能计算(HPC)系统的复杂性日益增加,需要引入自动化和数据驱动的方法,以支持系统管理员为增加系统可用性的努力。异常检测是改善可用性不可或缺的一部分,因为它减轻了系统管理员的负担,并减少了异常和解决方案之间的时间。但是,对当前的最新检测方法进行了监督和半监督,因此它们需要具有异常的人体标签数据集 - 在生产HPC系统中收集通常是不切实际的。基于聚类的无监督异常检测方法,旨在减轻准确的异常数据的需求,到目前为止的性能差。在这项工作中,我们通过提出RUAD来克服这些局限性,RUAD是一种新型的无监督异常检测模型。 Ruad比当前的半监督和无监督的SOA方法取得了更好的结果。这是通过考虑数据中的时间依赖性以及在模型体系结构中包括长短期限内存单元的实现。提出的方法是根据tier-0系统(带有980个节点的Cineca的Marconi100的完整历史)评估的。 RUAD在半监督训练中达到曲线(AUC)下的区域(AUC)为0.763,在无监督的训练中达到了0.767的AUC,这改进了SOA方法,在半监督训练中达到0.747的AUC,无需训练的AUC和0.734的AUC在无处不在的AUC中提高了AUC。训练。它还大大优于基于聚类的当前SOA无监督的异常检测方法,其AUC为0.548。
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A Digital Twin (DT) is a simulation of a physical system that provides information to make decisions that add economic, social or commercial value. The behaviour of a physical system changes over time, a DT must therefore be continually updated with data from the physical systems to reflect its changing behaviour. For resource-constrained systems, updating a DT is non-trivial because of challenges such as on-board learning and the off-board data transfer. This paper presents a framework for updating data-driven DTs of resource-constrained systems geared towards system health monitoring. The proposed solution consists of: (1) an on-board system running a light-weight DT allowing the prioritisation and parsimonious transfer of data generated by the physical system; and (2) off-board robust updating of the DT and detection of anomalous behaviours. Two case studies are considered using a production gas turbine engine system to demonstrate the digital representation accuracy for real-world, time-varying physical systems.
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智能制造系统以越来越多的速度部署,因为它们能够解释各种各样的感知信息并根据系统观察收集的知识采取行动。在许多情况下,智能制造系统的主要目标是快速检测(或预期)失败以降低运营成本并消除停机时间。这通常归结为检测从系统中获取的传感器日期内的异常。智能制造应用域构成了某些显着的技术挑战。特别是,通常有多种具有不同功能和成本的传感器。传感器数据特性随环境或机器的操作点而变化,例如电动机的RPM。因此,必须在工作点附近校准异常检测过程。在本文中,我们分析了从制造测试台部署的传感器中的四个数据集。我们评估了几种基于传统和ML的预测模型的性能,以预测传感器数据的时间序列。然后,考虑到一种传感器的稀疏数据,我们从高数据速率传感器中执行传输学习来执行缺陷类型分类。综上所述,我们表明可以实现预测性故障分类,从而为预测维护铺平了道路。
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燃气轮机发动机是复杂的机器,通常产生大量数据,并且需要仔细监控,以允许具有成本效益的预防性维护。在航空航天应用中,将所有测量数据返回到地面是昂贵的,通常会导致有用,高值,要丢弃的数据。因此,在实时检测,优先级和返回有用数据的能力是至关重要的。本文提出了由卷积神经网络常态模型描述的系统输出测量,实时优先考虑预防性维护决策者。由于燃气轮机发动机时变行为的复杂性,导出精确的物理模型难以困难,并且通常导致预测精度低的模型和与实时执行不相容。数据驱动的建模是一种理想的替代方案,生产高精度,资产特定模型,而无需从第一原理推导。我们提出了一种用于在线检测和异常数据的优先级的数据驱动系统。通过集成到深神经预测模型中的不确定管理,避免了偏离新的操作条件的数据评估。测试是对实际和合成数据进行的,显示对真实和合成故障的敏感性。该系统能够在低功耗嵌入式硬件上实时运行,目前正在部署Rolls-Royce Pearl 15发动机飞行试验。
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存在几种数据驱动方法,使我们的模型时间序列数据能够包括传统的基于回归的建模方法(即,Arima)。最近,在时间序列分析和预测的背景下介绍和探索了深度学习技术。询问的主要研究问题是在预测时间序列数据中的深度学习技术中的这些变化的性能。本文比较了两个突出的深度学习建模技术。比较了经常性的神经网络(RNN)长的短期记忆(LSTM)和卷积神经网络(CNN)基于基于TCN的时间卷积网络(TCN),并报告了它们的性能和训练时间。根据我们的实验结果,两个建模技术都表现了相当具有基于TCN的模型优于LSTM略微。此外,基于CNN的TCN模型比基于RNN的LSTM模型更快地构建了稳定的模型。
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Aiot技术的最新进展导致利用机器学习算法来检测网络物理系统(CPS)的操作失败的越来越受欢迎。在其基本形式中,异常检测模块从物理工厂监控传感器测量和致动器状态,并检测这些测量中的异常以识别异常操作状态。然而,由于该模型必须在存在高度复杂的系统动态和未知量的传感器噪声的情况下准确地检测异常,构建有效的异常检测模型是挑战性的。在这项工作中,我们提出了一种新的时序序列异常检测方法,称为神经系统识别和贝叶斯滤波(NSIBF),其中特制的神经网络架构被构成系统识别,即捕获动态状态空间中CP的动态模型;然后,通过跟踪系统的隐藏状态的不确定性随着时间的推移,自然地施加贝叶斯滤波算法的顶部。我们提供定性的和定量实验,并在合成和三个现实世界CPS数据集上具有所提出的方法,表明NSIBF对最先进的方法比较了对CPS中异常检测的最新方法。
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Anomaly detection on time series data is increasingly common across various industrial domains that monitor metrics in order to prevent potential accidents and economic losses. However, a scarcity of labeled data and ambiguous definitions of anomalies can complicate these efforts. Recent unsupervised machine learning methods have made remarkable progress in tackling this problem using either single-timestamp predictions or time series reconstructions. While traditionally considered separately, these methods are not mutually exclusive and can offer complementary perspectives on anomaly detection. This paper first highlights the successes and limitations of prediction-based and reconstruction-based methods with visualized time series signals and anomaly scores. We then propose AER (Auto-encoder with Regression), a joint model that combines a vanilla auto-encoder and an LSTM regressor to incorporate the successes and address the limitations of each method. Our model can produce bi-directional predictions while simultaneously reconstructing the original time series by optimizing a joint objective function. Furthermore, we propose several ways of combining the prediction and reconstruction errors through a series of ablation studies. Finally, we compare the performance of the AER architecture against two prediction-based methods and three reconstruction-based methods on 12 well-known univariate time series datasets from NASA, Yahoo, Numenta, and UCR. The results show that AER has the highest averaged F1 score across all datasets (a 23.5% improvement compared to ARIMA) while retaining a runtime similar to its vanilla auto-encoder and regressor components. Our model is available in Orion, an open-source benchmarking tool for time series anomaly detection.
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给定传感器读数随着时间的推移从电网上,我们如何在发生异常时准确地检测?实现这一目标的关键部分是使用电网传感器网络在电网上实时地在实时检测到自然故障或恶意的任何不寻常的事件。行业中现有的坏数据探测器缺乏鲁布布利地检测广泛类型的异常,特别是由于新兴网络攻击而造成的复杂性,因为它们一次在网格的单个测量快照上运行。新的ML方法更广泛适用,但通常不会考虑拓扑变化对传感器测量的影响,因此无法适应历史数据中的定期拓扑调整。因此,我们向DynWatch,基于域知识和拓扑知识算法用于使用动态网格上的传感器进行异常检测。我们的方法准确,优于实验中的现有方法20%以上(F-Measure);快速,在60K +分支机用中的每次传感器上平均运行小于1.7ms,使用笔记本电脑,并在图表的大小上线性缩放。
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在智能交通系统中,交通拥堵异常检测至关重要。运输机构的目标有两个方面:监视感兴趣领域的一般交通状况,并在异常拥堵状态下定位道路细分市场。建模拥塞模式可以实现这些目标,以实现全市道路的目标,相当于学习多元时间序列(MTS)的分布。但是,现有作品要么不可伸缩,要么无法同时捕获MTS中的空间信息。为此,我们提出了一个由数据驱动的生成方法组成的原则性和全面的框架,该方法可以执行可拖动的密度估计来检测流量异常。我们的方法在特征空间中的第一群段段,然后使用条件归一化流以在无监督的设置下在群集级别识别异常的时间快照。然后,我们通过在异常群集上使用内核密度估计器来识别段级别的异常。关于合成数据集的广泛实验表明,我们的方法在召回和F1得分方面显着优于几种最新的拥塞异常检测和诊断方法。我们还使用生成模型来采样标记的数据,该数据可以在有监督的环境中训练分类器,从而减轻缺乏在稀疏设置中进行异常检测的标记数据。
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鉴于在现实世界应用中缺乏异常情况,大多数文献一直集中在建模正态上。学到的表示形式可以将异常检测作为正态性模型进行训练,以捕获正常情况下的某些密钥数据规律性。在实际环境中,尤其是工业时间序列异常检测中,我们经常遇到有大量正常操作数据以及随时间收集的少量异常事件的情况。这种实际情况要求方法学来利用这些少量的异常事件来创建更好的异常检测器。在本文中,我们介绍了两种方法来满足这种实际情况的需求,并将其与最近开发的最新技术进行了比较。我们提出的方法锚定在具有自回归(AR)模型的正常运行的代表性学习以及损失组件上,以鼓励表示正常与几个积极示例的表示形式。我们将提出的方法应用于两个工业异常检测数据集,并与文献相比表现出有效的性能。我们的研究还指出了在实际应用中采用此类方法的其他挑战。
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The detection of anomalies in time series data is crucial in a wide range of applications, such as system monitoring, health care or cyber security. While the vast number of available methods makes selecting the right method for a certain application hard enough, different methods have different strengths, e.g. regarding the type of anomalies they are able to find. In this work, we compare six unsupervised anomaly detection methods with different complexities to answer the questions: Are the more complex methods usually performing better? And are there specific anomaly types that those method are tailored to? The comparison is done on the UCR anomaly archive, a recent benchmark dataset for anomaly detection. We compare the six methods by analyzing the experimental results on a dataset- and anomaly type level after tuning the necessary hyperparameter for each method. Additionally we examine the ability of individual methods to incorporate prior knowledge about the anomalies and analyse the differences of point-wise and sequence wise features. We show with broad experiments, that the classical machine learning methods show a superior performance compared to the deep learning methods across a wide range of anomaly types.
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粒子加速器是复杂的设施,可产生大量的结构化数据,并具有明确的优化目标以及精确定义的控制要求。因此,它们自然适合数据驱动的研究方法。来自传感器和监视加速器形式的多元时间序列的数据。在加速器控制和诊断方面,快速的先发制人方法是高度首选的,数据驱动的时间序列预测方法的应用尤其有希望。这篇综述提出了时间序列预测问题,并总结了现有模型,并在各个科学领域的应用中进行了应用。引入了粒子加速器领域中的几次和将来的尝试。预测到粒子加速器的时间序列的应用显示出令人鼓舞的结果和更广泛使用的希望,现有的问题(例如数据一致性和兼容性)已开始解决。
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迁移率和加热部门的连续电气化将对分布网格运行引入新的挑战。不协调的灵活单元激活,例如,电动车辆同时充电作为对价格信号的反应,可以系统地触发变压器或线路保护。实时识别这种快速升高的灵活性激活将允许抵消以避免潜在的社会和财务成本。在这项工作中,提出了一种用于识别快速升高灵活性激活事件的新型数据处理流水线。管道结合了无监督事件检测和开放式分类的技术。实际负载数据的系统评估演示了所提出的管道的主要构建块可以通过满足分布式事件检测架构中应用的重要要求的方法来实现。为了检测灵活性激活事件,识别了上部性能限制。此外,证明了与广泛应用的闭合分类器相比,用于分类的开放式分类器的应用可以提高性能。
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新的纳米级技术的出现对辐射环境中的可靠电子系统造成了重大挑战。少数种类的辐射等全电离剂量(TID)效应通常导致在这种纳米级电子设备上的永久性损坏,以及当前最先进的技术,以使用昂贵的辐射硬化装置。本文重点介绍了一种新颖且不同的方法:在消费者电子级现场可编程门阵列(FPGA)上使用机器学习算法来解决TID效果并在停止工作之前监控它们替换。这种情况有一个研究挑战,以期待电路板因TID效应而导致总失效。我们观察到γ辐射下FPGA板的内部测量,并使用了三种不同的异常检测机学习(ML)算法来检测伽马辐射环境中的传感器测量中的异常。统计结果表明伽马辐射曝光水平与板测量之间的高度显着关系。此外,我们的异常检测结果表明,具有径向基函数内核的单级支持向量机的平均召回得分为0.95。此外,在电路板停止工作之前,可以检测到所有异常。
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A new Lossy Causal Temporal Convolutional Neural Network Autoencoder for anomaly detection is proposed in this work. Our framework uses a rate-distortion loss and an entropy bottleneck to learn a compressed latent representation for the task. The main idea of using a rate-distortion loss is to introduce representation flexibility that ignores or becomes robust to unlikely events with distinctive patterns, such as anomalies. These anomalies manifest as unique distortion features that can be accurately detected in testing conditions. This new architecture allows us to train a fully unsupervised model that has high accuracy in detecting anomalies from a distortion score despite being trained with some portion of unlabelled anomalous data. This setting is in stark contrast to many of the state-of-the-art unsupervised methodologies that require the model to be only trained on "normal data". We argue that this partially violates the concept of unsupervised training for anomaly detection as the model uses an informed decision that selects what is normal from abnormal for training. Additionally, there is evidence to suggest it also effects the models ability at generalisation. We demonstrate that models that succeed in the paradigm where they are only trained on normal data fail to be robust when anomalous data is injected into the training. In contrast, our compression-based approach converges to a robust representation that tolerates some anomalous distortion. The robust representation achieved by a model using a rate-distortion loss can be used in a more realistic unsupervised anomaly detection scheme.
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Due to the issue that existing wireless sensor network (WSN)-based anomaly detection methods only consider and analyze temporal features, in this paper, a self-supervised learning-based anomaly node detection method based on an autoencoder is designed. This method integrates temporal WSN data flow feature extraction, spatial position feature extraction and intermodal WSN correlation feature extraction into the design of the autoencoder to make full use of the spatial and temporal information of the WSN for anomaly detection. First, a fully connected network is used to extract the temporal features of nodes by considering a single mode from a local spatial perspective. Second, a graph neural network (GNN) is used to introduce the WSN topology from a global spatial perspective for anomaly detection and extract the spatial and temporal features of the data flows of nodes and their neighbors by considering a single mode. Then, the adaptive fusion method involving weighted summation is used to extract the relevant features between different models. In addition, this paper introduces a gated recurrent unit (GRU) to solve the long-term dependence problem of the time dimension. Eventually, the reconstructed output of the decoder and the hidden layer representation of the autoencoder are fed into a fully connected network to calculate the anomaly probability of the current system. Since the spatial feature extraction operation is advanced, the designed method can be applied to the task of large-scale network anomaly detection by adding a clustering operation. Experiments show that the designed method outperforms the baselines, and the F1 score reaches 90.6%, which is 5.2% higher than those of the existing anomaly detection methods based on unsupervised reconstruction and prediction. Code and model are available at https://github.com/GuetYe/anomaly_detection/GLSL
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在能源系统的数字化中,传感器和智能电表越来越多地用于监视生产,运行和需求。基于智能电表数据的异常检测对于在早期阶段识别潜在的风险和异常事件至关重要,这可以作为及时启动适当动作和改善管理的参考。但是,来自能源系统的智能电表数据通常缺乏标签,并且包含噪声和各种模式,而没有明显的周期性。同时,在不同的能量场景中对异常的模糊定义和高度复杂的时间相关性对异常检测构成了巨大的挑战。许多传统的无监督异常检测算法(例如基于群集或基于距离的模型)对噪声不强大,也不完全利用时间序列中的时间依赖性以及在多个变量(传感器)中的其他依赖关系。本文提出了一种基于带有注意机制的变异复发自动编码器的无监督异常检测方法。凭借来自智能电表的“肮脏”数据,我们的方法预示了缺失的值和全球异常,以在训练中缩小其贡献。本文与基于VAE的基线方法和其他四种无监督的学习方法进行了定量比较,证明了其有效性和优势。本文通过一项实际案例研究进一步验证了所提出的方法,该研究方法是检测工业加热厂的供水温度异常。
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非侵入性负载监控(NILM)是将总功率消耗分为单个子组件的任务。多年来,已经合并了信号处理和机器学习算法以实现这一目标。关于最先进的方法,进行了许多出版物和广泛的研究工作,以涉及最先进的方法。科学界最初使用机器学习工具的尼尔姆问题制定和描述的最初兴趣已经转变为更实用的尼尔姆。如今,我们正处于成熟的尼尔姆时期,在现实生活中的应用程序方案中尝试使用尼尔姆。因此,算法的复杂性,可转移性,可靠性,实用性和普遍的信任度是主要的关注问题。这篇评论缩小了早期未成熟的尼尔姆时代与成熟的差距。特别是,本文仅对住宅电器的尼尔姆方法提供了全面的文献综述。本文分析,总结并介绍了大量最近发表的学术文章的结果。此外,本文讨论了这些方法的亮点,并介绍了研究人员应考虑的研究困境,以应用尼尔姆方法。最后,我们表明需要将传统分类模型转移到一个实用且值得信赖的框架中。
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