Thanasis Kotsiopoulos’s research while affiliated with Centre for Research and Technology Hellas and other places

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Publications (13)


Anomaly Detection in Industrial Processes: Supervised vs. Unsupervised Learning and the Role of Explainability
  • Article

January 2025

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15 Reads

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3 Citations

Avraam Bardos

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Panagiotis Doupidis

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Thanasis Kotsiopoulos

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[...]

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Background Anomaly detection is vital in industrial settings for identifying abnormal behaviors that suggest faults or malfunctions. Artificial intelligence (AI) offers significant potential to assist humans in addressing these challenges. Methods This study compares the performance of supervised and unsupervised machine learning (ML) techniques for anomaly detection. Additionally, model-specific explainability methods were employed to interpret the outputs. A novel explainability approach, MLW-XAttentIon, based on causal reasoning in attention networks, was proposed to visualize the inference process of transformer models. Results Experimental results revealed that unsupervised models perform well without requiring labeled data, offering significant promise. In contrast, supervised models demonstrated greater robustness and reliability. Conclusions Unsupervised ML techniques present a feasible, resource-efficient option for anomaly detection, while supervised methods remain more reliable for critical applications. The MLW-XAttentIon approach enhances interpretability of transformer-based models, contributing to trust and transparency in AI-driven anomaly detection systems.





Figure 1: MusicGen-Small vs. proposed TinyTTM.
Performance on the different T5 configurations. FT: fine-tuned on MusicBench dataset (train set).
Performance (mean ± standard deviation) of distilled LM with various setups. H: Student loss, S: Teacher loss, mse: Intermediate MSE loss. S i : Sampling strategy i from 2.2.2.
Performance on EnCodec model. w.f.: weight factor
Performance comparison (for 3 runs with different seeds) between the proposed TinyTTM model and MusicGen- Small on the MusicBench test set A.
Exploring compressibility of transformer based text-to-music (TTM) models
  • Preprint
  • File available

June 2024

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73 Reads

State-of-the art Text-To-Music (TTM) generative AI models are large and require desktop or server class compute, making them infeasible for deployment on mobile phones. This paper presents an analysis of trade-offs between model compression and generation performance of TTM models. We study compression through knowledge distillation and specific modifications that enable applicability over the various components of the TTM model (encoder, generative model and the decoder). Leveraging these methods we create TinyTTM (89.2M params) that achieves a FAD of 3.66 and KL of 1.32 on MusicBench dataset, better than MusicGen-Small (557.6M params) but not lower than MusicGen-small fine-tuned on MusicBench.

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Cyber-Resilience Enhancement Framework in Smart Grids

February 2023

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86 Reads

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5 Citations

Power Systems

Reliability, resilience and Quality of Service are essential features of modern electric power-system operations that reflect the transition of electric energy infrastructure towards the smart grid deployment. Leveraging the Software Defined Networking technology and other cybersecurity cutting-edge technologies and algorithms, this work aims to bring a innovation in the modern Electrical Power and Energy System environment. To this end, we propose a cyber-resilience enhancement framework with the aim to modernize the traditional electrical grid and provide solutions in the domains of voltage and frequency restoration, cybersecurity and network Quality of Service. Based on the results, the framework is able to detect accurately cyberattacks and perform network path re-allocation by maximizing the Quality of Service in a more accurate way than other state of art algorithms.




Figure 1. SDN-microSENSE Architecture-Structural View.
Figure 2 depicts the SDN-microSENSE business logic based on the SDN architectural model. It comprises three main conceptual frameworks [33], namely (a) SDN-microSENSE Risk Assessment Framework (S-RAF), (b) Cross-Layer Energy Prevention and Detection System (XL-EPDS) and (c) SDN-enabled Self-healing Framework (SDN-SELF) that are deployed throughout the four SDN planes: (a) Data Plane, (b) Control Plane, (c) Application Plane and (d) Management Plane. The term conceptual framework refers to a set of functions and relationships within a research area [33]. Therefore, the SDN-microSENSE frameworks mentioned earlier focus on the following cybersecurity-related research areas: (a) Risk assessment, (b) intrusion detection and correlation and (d) self healing and recovery. Each of the SDN-microSENSE frameworks takes full advantage of the SDN technology in order to detect, mitigate or even prevent possible intrusions. In particular, S-RAF instructs the SDN Controller (SDN-C) to redirect the potential cyberattackers to the EPES/SG honeypots. The EPES/SG honeypots constitute a security control of S-RAF. Next, XL-EPDS uses statistics originating from the SDN-C to detect possible anomalies or cyberattacks related to the entire SDN network. Finally, SDN-SELF communicates with the SDN-C in order to mitigate possible intrusions and anomalies. The following subsections analyse the components and the interfaces of each SDN-microSENSE framework. A more detailed view of the SDN-microSENSE architecture, along with the interfaces between the various planes, is depicted in Figure 1. The structural view is based on the SDN architecture, as defined by the Open Networking Foundation (ONF) [34] and Request for Comments (RFC) 7426 [35], and follows the rationale of decoupling the network control with the forwarding functions. Therefore, according to the above specifications, the conceptual frameworks are placed within the Data, Controller, Application, and Management Planes. In particular, the Data Plane contains the EPES/SG infrastructure, the honeypots and the SDN switches. The Controller Plane consists of multiple SDN controllers that receive guidance from the Application and Management Planes and configure the Data Plane accordingly. The conceptual frameworks and their components are placed within the Application Plane. In this plane, the most important operational decisions take place, such as the detection of a cyberattack or the decision to isolate a malicious network flow. Finally,
Figure 2. SDN-microSENSE Business Logic.
SDN-Based Resilient Smart Grid: The SDN-microSENSE Architecture

September 2021

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360 Reads

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32 Citations

Digital

The technological leap of smart technologies and the Internet of Things has advanced the conventional model of the electrical power and energy systems into a new digital era, widely known as the Smart Grid. The advent of Smart Grids provides multiple benefits, such as self-monitoring, self-healing and pervasive control. However, it also raises crucial cybersecurity and privacy concerns that can lead to devastating consequences, including cascading effects with other critical infrastructures or even fatal accidents. This paper introduces a novel architecture, which will increase the Smart Grid resiliency, taking full advantage of the Software-Defined Networking (SDN) technology. The proposed architecture called SDN-microSENSE architecture consists of three main tiers: (a) Risk assessment, (b) intrusion detection and correlation and (c) self-healing. The first tier is responsible for evaluating dynamically the risk level of each Smart Grid asset. The second tier undertakes to detect and correlate security events and, finally, the last tier mitigates the potential threats, ensuring in parallel the normal operation of the Smart Grid. It is noteworthy that all tiers of the SDN-microSENSE architecture interact with the SDN controller either for detecting or mitigating intrusions.


Citations (9)


... It can be classified as supervised or unsupervised. These two techniques are applied in different situations [5,6]. ...

Reference:

Artificial intelligence advances in cardiovascular imaging
Anomaly Detection in Industrial Processes: Supervised vs. Unsupervised Learning and the Role of Explainability
  • Citing Article
  • January 2025

... In particular, AI-driven fault prediction methods have been proposed to address challenges created by incomplete datasets, utilizing probabilistic models and uncertainty quantification techniques to enhance reliability and robustness [47]. Moreover, recent research has highlighted the importance of explainable AI in industrial applications, ensuring transparency and interpretability in automated decision-making processes [48]. ...

Enhancing transparency and trust in AI-powered manufacturing: A survey of explainable AI (XAI) applications in smart manufacturing in the era of industry 4.0/5.0
  • Citing Article
  • December 2024

ICT Express

... From an overall perspective, the identified papers focus on four topics, namely AI support, digital twins, cloud/edge deployment as well as data security. Regarding AI support, Wang et al. propose in [68] a knowledge-driven autonomous manufacturing system using a pretrained transformer model, while [69,70] aim to support human aspects through AI. Alberti et al. construct in [69] data pipelines for humancentered AI manufacturing systems, and Kotsiopoulous et al. aim at defect detection using explainable AI and human-in-the-loop approaches in [70]. ...

Revolutionizing defect recognition in hard metal industry through AI explainability, human-in-the-loop approaches and cognitive mechanisms
  • Citing Article
  • July 2024

Expert Systems with Applications

... The CREF (Cyber Resiliency Engineering Framework) provides an architectural approach focused on building or enhancing resilience in response to cyber threats. This framework does not address resilience or business continuity objectives for threats that are not cyber-related, such as natural disasters or human errors [24], [25], [26]. ...

Cyber-Resilience Enhancement Framework in Smart Grids
  • Citing Chapter
  • February 2023

Power Systems

... In [15], the authors present a comparative study among the known fault detection techniques Local Outlier Factor and Isolation Forest as well as a proposed methodology called Standardised Mahalanobis Distance is presented. The study is focusing on the challenging problem of fault detection on bearings and rotating machines using vibration sensors' data. ...

Fault Detection on Bearings and Rotating Machines based on Vibration Sensors Data
  • Citing Conference Paper
  • December 2021

... The study in [23] introduced an SDN-based architecture aimed at enhancing the resilience of smart grids while also addressing intrusion detection and mitigation. The proposed solution leverages SDN technology across three key modules: the SDN-microSENSE Risk Assessment Framework (S-RAF), the Cross-Layer Energy Prevention and Detection System (XL-EPDS), and the SDN-enabled Self-healing Framework (SDN-SELF). ...

SDN-Based Resilient Smart Grid: The SDN-microSENSE Architecture

Digital

... An examination of existing studies provides significant insights applicable to MASS cybersecurity. The cybersecurity challenges in autonomous systems" [33] [34] identifies common issues and proposes methods; however, this study uniquely addresses MASS challenges, including spacespecific threats to cybersecurity defenses, injection attacks, and managing long-distance communication complexities in encompasses diverse cyber threats faced by MASS during open-sea navigation. Lastly, "Space Systems Cybersecurity Guidelines" [37] provide guidelines, but adapting these to MASS specifics, including its independence, communication challenges, and integration of space and sea technologies, is crucial. ...

Enabling Cyber-attack Mitigation Techniques in a Software Defined Network
  • Citing Conference Paper
  • July 2021

... By calculating the second-order gradients of the loss function to reduce loss and employing advanced regularization (L1 and L2), XGBoost can minimize overfitting, improve model generalization, and enhance performance. Additionally, this approach can be interpreted rapidly and efficiently to manage large datasets [80,82]. ...

Machine Learning and Deep Learning in Smart Manufacturing: The Smart Grid Paradigm

Computer Science Review

... In light of this, several authors have employed both supervised and unsupervised machine learning approaches to make intelligent deductions from schemes. For instance, the authors in [13] employed deep neural networks (DNNs) to ensure effective monitoring of metal production for quality control. This guarantees the inspection of defective metal parts, thus, serving to help curb wastage. ...

Deep multi-sensorial data analysis for production monitoring in hard metal industry

The International Journal of Advanced Manufacturing Technology