在数据挖掘中,异常检测(英语:anomaly detection)对不符合预期模式或数据集中其他项目的项目、事件或观测值的识别。通常异常项目会转变成银行欺诈、结构缺陷、医疗问题、文本错误等类型的问题。异常也被称为离群值、新奇、噪声、偏差和例外。 特别是在检测滥用与网络入侵时,有趣性对象往往不是罕见对象,但却是超出预料的突发活动。这种模式不遵循通常统计定义中把异常点看作是罕见对象,于是许多异常检测方法(特别是无监督的方法)将对此类数据失效,除非进行了合适的聚集。相反,聚类分析算法可能可以检测出这些模式形成的微聚类。 有三大类异常检测方法。[1] 在假设数据集中大多数实例都是正常的前提下,无监督异常检测方法能通过寻找与其他数据最不匹配的实例来检测出未标记测试数据的异常。监督式异常检测方法需要一个已经被标记“正常”与“异常”的数据集,并涉及到训练分类器(与许多其他的统计分类问题的关键区别是异常检测的内在不均衡性)。半监督式异常检测方法根据一个给定的正常训练数据集创建一个表示正常行为的模型,然后检测由学习模型生成的测试实例的可能性。

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异常检测已经得到了广泛的研究和应用。建立一个有效的异常检测系统需要研究者和开发者从嘈杂的数据中学习复杂的结构,识别动态异常模式,用有限的标签检测异常。与经典方法相比,近年来深度学习技术的进步极大地提高了异常检测的性能,并将异常检测扩展到广泛的应用领域。本教程将帮助读者全面理解各种应用领域中基于深度学习的异常检测技术。首先,我们概述了异常检测问题,介绍了在深度模型时代之前采用的方法,并列出了它们所面临的挑战。然后我们调查了最先进的深度学习模型,范围从构建块神经网络结构,如MLP, CNN,和LSTM,到更复杂的结构,如自动编码器,生成模型(VAE, GAN,基于流的模型),到深度单类检测模型,等等。此外,我们举例说明了迁移学习和强化学习等技术如何在异常检测问题中改善标签稀疏性问题,以及在实际中如何收集和充分利用用户标签。其次,我们讨论来自LinkedIn内外的真实世界用例。本教程最后讨论了未来的趋势。

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In the last decade, extended efforts have been poured into energy efficiency. Several energy consumption datasets were henceforth published, with each dataset varying in properties, uses and limitations. For instance, building energy consumption patterns are sourced from several sources, including ambient conditions, user occupancy, weather conditions and consumer preferences. Thus, a proper understanding of the available datasets will result in a strong basis for improving energy efficiency. Starting from the necessity of a comprehensive review of existing databases, this work is proposed to survey, study and visualize the numerical and methodological nature of building energy consumption datasets. A total of thirty-one databases are examined and compared in terms of several features, such as the geographical location, period of collection, number of monitored households, sampling rate of collected data, number of sub-metered appliances, extracted features and release date. Furthermore, data collection platforms and related modules for data transmission, data storage and privacy concerns used in different datasets are also analyzed and compared. Based on the analytical study, a novel dataset has been presented, namely Qatar university dataset, which is an annotated power consumption anomaly detection dataset. The latter will be very useful for testing and training anomaly detection algorithms, and hence reducing wasted energy. Moving forward, a set of recommendations is derived to improve datasets collection, such as the adoption of multi-modal data collection, smart Internet of things data collection, low-cost hardware platforms and privacy and security mechanisms. In addition, future directions to improve datasets exploitation and utilization are identified, including the use of novel machine learning solutions, innovative visualization tools and explainable recommender systems.

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In the last decade, extended efforts have been poured into energy efficiency. Several energy consumption datasets were henceforth published, with each dataset varying in properties, uses and limitations. For instance, building energy consumption patterns are sourced from several sources, including ambient conditions, user occupancy, weather conditions and consumer preferences. Thus, a proper understanding of the available datasets will result in a strong basis for improving energy efficiency. Starting from the necessity of a comprehensive review of existing databases, this work is proposed to survey, study and visualize the numerical and methodological nature of building energy consumption datasets. A total of thirty-one databases are examined and compared in terms of several features, such as the geographical location, period of collection, number of monitored households, sampling rate of collected data, number of sub-metered appliances, extracted features and release date. Furthermore, data collection platforms and related modules for data transmission, data storage and privacy concerns used in different datasets are also analyzed and compared. Based on the analytical study, a novel dataset has been presented, namely Qatar university dataset, which is an annotated power consumption anomaly detection dataset. The latter will be very useful for testing and training anomaly detection algorithms, and hence reducing wasted energy. Moving forward, a set of recommendations is derived to improve datasets collection, such as the adoption of multi-modal data collection, smart Internet of things data collection, low-cost hardware platforms and privacy and security mechanisms. In addition, future directions to improve datasets exploitation and utilization are identified, including the use of novel machine learning solutions, innovative visualization tools and explainable recommender systems.

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