2021
Authors
Petrescu, A; Cvijic, M; Bezy, S; Santos, P; Duchenne, J; Orlowska, M; Pedrosa, J; Degtiarova, G; Van Keer, J; Von Bardeleben, S; Droogne, W; Van Cleemput, J; Bogaert, J; D"hooge, J; Voigt, J;
Publication
European Heart Journal - Cardiovascular Imaging
Abstract
2021
Authors
Tisljaric, L; Fernandes, S; Caric, T; Gama, J;
Publication
APPLIED SCIENCES-BASEL
Abstract
The increased development of urban areas results in a larger number of vehicles on the road network, leading to traffic congestion, which often leads to potentially dangerous situations that can be described as anomalies. The tensor-based methods emerged only recently in applications related to traffic anomaly detection. They outperform other models regarding simultaneously capturing spatial and temporal components, which are of immense importance in traffic dataset analysis. This paper presents a tensor-based method for extracting the spatiotemporal road traffic patterns represented with the speed transition matrices, with the goal of anomaly detection. A novel anomaly detection approach is presented, which relies on computing the center of mass of the observed traffic patterns. The method was evaluated on a large road traffic dataset and was able to detect the most anomalous parts of the urban road network. By analyzing spatial and temporal components of the most anomalous traffic patterns, sources of anomalies can be identified. Results were validated using the extracted domain knowledge from the Highway Capacity Manual. The anomaly detection model achieved a precision score of 92.88%. Therefore, this method finds its usages for safety experts in detecting potentially dangerous road segments, urban traffic planners, and routing applications.
2021
Authors
Allahdadi, A; Pernes, D; Cardoso, JS; Morla, R;
Publication
NEURAL COMPUTING & APPLICATIONS
Abstract
The present work introduces a hybrid integration of the self-organizing map and the hidden Markov model (HMM) for anomaly detection in 802.11 wireless networks. The self-organizing hidden Markov model map (SOHMMM) deals with the spatial connections of HMMs, along with the inherent temporal dependencies of data sequences. In essence, an HMM is associated with each neuron of the SOHMMM lattice. In this paper, the SOHMMM algorithm is employed for anomaly detection in 802.11 wireless access point usage data. Furthermore, we extend the SOHMMM online gradient descent unsupervised learning algorithm for multivariate Gaussian emissions. The experimental analysis uses two types of data: synthetic data to investigate the accuracy and convergence of the SOHMMM algorithm and wireless simulation data to verify the significance and efficiency of the algorithm in anomaly detection. The sensitivity and specificity of the SOHMMM algorithm in anomaly detection are compared to two other approaches, namely HMM initialized with universal background model (HMM-UBM) and SOHMMM with zero neighborhood (Z-SOHMMM). The results from the wireless simulation experiments show that SOHMMM outperformed the aforementioned approaches in all the presented anomalous scenarios.
2021
Authors
Farsani, KT; Dehghani, M; Abolpour, R; Vafamand, N; Javadi, MS; Wang, F; Catalao, JPS;
Publication
2021 21ST IEEE INTERNATIONAL CONFERENCE ON ENVIRONMENT AND ELECTRICAL ENGINEERING AND 2021 5TH IEEE INDUSTRIAL AND COMMERCIAL POWER SYSTEMS EUROPE (EEEIC/I&CPS EUROPE)
Abstract
Nowadays, recent advances in information technology and communication facilitates using networked controlled systems in different industrial plants. Whereas data is transferred among different components of the networked systems, they are vulnerable to various types of attacks. This important issue in nowadays industrial plants should be treated logically and reasonable protection mechanisms to mitigate such attacks should be provided. This paper considers delay attack impacts on frequency regulation of an electric vehicle aggregator (EVA) system. The command control action is received by the EVA through an imperfect channel containing uncertainties subject to the time-delay attack. A systematic approach based on a direct search algorithm (DSA) is developed to design a resilient proportional-integral (PI) controller for mitigating such attacks. The proposed DSA provides low-conservative results, explores the design space to find a feasible solution, and computes the PI controller gains to assure the stability of the EVA system in the presence of the delay attack. Stability analysis and numerical simulations for a typical attacked EVA frequency regulation are given to show the effectiveness of the developed controller.
2021
Authors
Doré, NI; Teixeira, AAC;
Publication
Global Journal of Emerging Market Economies
Abstract
The factors required to achieve sustainable economic growth in a country are debated for decades, and empirical research in this regard continues to grow. Given the relevance of the topic and the absence of a comprehensive, systematic literature review, we used bibliometric techniques to examine and document several aspects in the empirical literature related to growth, from 1991 to 2020. Five main results are worth highlighting: (a) the share of empirical articles on economic growth show a clear upward trend; (b) among all the groups of countries considered, the emerging economies (EEs) have received the most scientific attention; (c) the economic growth processes of the Latin American and Caribbean EEs have observed negligible scientific attention; (d) the very long-run studies comprise a residual share among the empirical literature on growth; (e) the extant empirical studies on economic growth have addressed mainly the impact of “macroeconomic conditions.” Our findings suggest there is a need to redirect the empirical growth agenda, so as to encourage more scientific attention devoted to the analysis of key determinants of economic growth in the very long run. There should also be increased scrutiny of the processes of economic growth in Latin American and Caribbean EEs. © 2021 Emerging Markets Forum, Washington DC.
2021
Authors
Rossi, ALD; Soares, C; de Souza, BF; de Carvalho, ACPDF;
Publication
INFORMATION SCIENCES
Abstract
Data stream mining needs to deal with scenarios where data distribution can change over time. As a result, different learning algorithms can be more suitable in different time periods. This paper proposes micro-MetaStream, a meta-learning based method to recommend the most suitable learning algorithm for each new example arriving in a data stream. It is an evolution of MetaStream, which recommends learning algorithms for batches of examples. By using a unitary granularity, micro-MetaStream is able to respond more efficiently to changes in data distribution than its predecessor. The meta-data combines meta-features, characteristics describing recent data, with base-level features, the original variables of the new example. In experiments on real-world regression data streams, micro-metaStream outperformed MetaStream and a baseline method at the meta-level and frequently improved the predictive performance at the base-level.
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