Stefanos H. Panagiotou

Mr. Stefanos H. Panagiotou

Computer Engineering and Informatics, University of Patras, Rio, Greece
orcid
Ph.D. Candidate

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 February 2023 in Machines
Verified
Journal Article
Open access
PDF file
SASamuel Olaiya Afolaranmi
Samuel Olaiya Afolaranmi
MDMichalis Drakoulelis
Michalis Drakoulelis
GFGabriel Filios
Gabriel Filios
CMChristian Melchiorre
Christian Melchiorre
SNSotiris Nikoletseas
Sotiris Nikoletseas
KTKonstantinos Timpilis
Konstantinos Timpilis
In the food and beverage industry, many foods, beers, and soft drinks need to be pasteurized in order to minimize the effect of micro-organisms on the physical stability, quality, and flavour of the product. Although modern tunnel pasteurizers provide integrated solutions for precise process monitoring and control, a great number of packaging plants continue to operate with legacy pasteurizers that require irregular manual measurements to be performed by shop floor operators in order to monitor the process. In this context, the present paper presents zPasteurAIzer, an end-to-end system that provides real-time quality monitoring for legacy tunnel pasteurization machines and constitutes a low-cost alternative to replacement or the upgrading of installed equipment by leveraging IoT technologies and AI-enabled virtual sensing techniques. We share details on the design and implementation of the system, which is based on a microservice-oriented architecture and includes functionalities such as configuration of the pasteurizer machine, data acquisition, and preprocessing methodology as well as machine learning-based estimation and live dashboard monitoring of the process parameters. Experimental work has been conducted in a real-world use case at a large brewing manufacturing plant in Greece, and the results indicate the value and potential of the proposed system.

12 January 2023 in Sensors
Verified
Journal Article
Open access
PDF file
IKIoannis Katsidimas
Ioannis Katsidimas
Vassilis KostopoulosVassilis Kostopoulos
Vassilis Kostopoulos
AKAthanasios Kotzakolios
Athanasios Kotzakolios
SNSotiris Nikoletseas
Sotiris Nikoletseas
SPStefanos H. Panagiotou
Stefanos H. Panagiotou
CTConstantinos Tsakonas
Constantinos Tsakonas
Recent advances both in hardware and software have facilitated the embedded intelligence (EI) research field, and enabled machine learning and decision-making integration in resource-scarce IoT devices and systems, realizing “conscious” and self-explanatory objects (smart objects). In the context of the broad use of WSNs in advanced IoT applications, this is the first work to provide an extreme-edge system, to address structural health monitoring (SHM) on polymethyl methacrylate (PPMA) thin-plate. To the best of our knowledge, state-of-the-art solutions primarily utilize impact positioning methods based on the time of arrival of the stress wave, while in the last decade machine learning data analysis has been performed, by more expensive and resource-abundant equipment than general/development purpose IoT devices, both for the collection and the inference stages of the monitoring system. In contrast to the existing systems, we propose a methodology and a system, implemented by a low-cost device, with the benefit of performing an online and on-device impact localization service from an agnostic perspective, regarding the material and the sensors’ location (as none of those attributes are used). Thus, a design of experiments and the corresponding methodology to build an experimental time-series dataset for impact detection and localization is proposed, using ceramic piezoelectric transducers (PZTs). The system is excited with a steel ball, varying the height from which it is released. Based on TinyML technology for embedding intelligence in low-power devices, we implement and validate random forest and shallow neural network models to localize in real-time (less than 400 ms latency) any occurring impacts on the structure, achieving higher than 90% accuracy.

23 December 2025 in Big Data and Cognitive Computing
Verified
Journal Article
Open access
PDF file
PGPetros Gkertzos
Petros Gkertzos
JGJohannes Gerritzen
Johannes Gerritzen
CTConstantinos Tsakonas
Constantinos Tsakonas
SPStefanos H. Panagiotou
Stefanos H. Panagiotou
AKAthanasios Kotzakolios
Athanasios Kotzakolios
SNSotiris Nikoletseas
Sotiris Nikoletseas
Modern impact monitoring systems combine multiple inputs with machine learning (ML) models for impact detection, localization, and event assessment. Their accuracy relies on large, event-representative datasets, used for algorithmic development and ML model training. High-fidelity numerical models can provide augmented datasets by overcoming the cost and time limitations of experimental methods. This research presents an end-to-end numerical methodology for impact detection based on simulation (training) and experimental (testing) data. Initially, a finite element model (FEM) of our experimental setup utilizing piezoelectric transducer (PZT) sensors mounted on a thermoplastic plate is created. From the experimental impact signals, a few consistent cases are identified for feature extraction. A design of experiments explores the range of each parameter, and through surrogate optimization, the material and piezoelectric properties of the setup are determined. Subsequently, a virtual dataset, involving multiple impact cases, is created to train the ML models performing impact detection. Testing with experimental data shows results consistent with literature studies that used only experimental data for both training and testing. This work provides a systematic methodology for representative dataset generation and impact monitoring through ML, while addressing accurate FEM parameter identification from a few experimental tries.

23 November 2021
Verified
Conference Paper
Closed access
VVVasileios Vlachos
Vasileios Vlachos
IKIoannis Katsidimas
Ioannis Katsidimas
EKEmmanouil Kerimakis
Emmanouil Kerimakis
SNSotiris Nikoletseas
Sotiris Nikoletseas
SPStefanos H. Panagiotou
Stefanos H. Panagiotou
PSPaul Spirakis
Paul Spirakis
The adoption of good security practices for the e-commerce business is a challenging problem. The enforcement of a strict legal framework is not always effective. On the other hand, simple recommendations and raising awareness actions are not sufficient to prioritize the necessity of secure e-commerce websites. Our approach is a combination of self-assessment, self-improvement and self-regulation incentivization activities, implemented in the observAtory for Security and PrIvacy DAta (ASPIDA) system. To minimize security and privacy issues in commercial websites and e-shops, we propose a hybrid, multi-dimensional methodology to gather, monitor and analyze various indicators and metrics, into an integrated system. Although several interesting efforts have been developed for monitoring compliance with basic cybersecurity principles, their implementation is limited without any stimulus for the participants. ASPIDA automatically analyzes a set of technical security and privacy characteristics of commercial websites and correlates the output with the results of questionnaires answered by the respective owners, web-developers and webadministrators. Positive evaluation in the automatic testing and participation in the e-commerce cybersecurity survey generates a digital badge of good practices for the specific website. The digital badge is a premium for informed e-buyers that are aware of the impact of recent catastrophic security incidents and the importance of personal data.