Theodore Zahariadis

Dr. Theodore Zahariadis

National and Kapodistrian University of Athens
orcid

Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

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

Representative Publications

View All Publications
23 December 2019 in Sensors
Verified
Journal Article
Open access
PDF file
AAAngelos Angelopoulos
Angelos Angelopoulos
Emmanouel T. MichailidisEmmanouel T. Michailidis
Emmanouel T. Michailidis
Nikolaos NomikosNikolaos Nomikos
Nikolaos Nomikos
PTPanagiotis Trakadas
Panagiotis Trakadas
AHAntonios Hatziefremidis
Antonios Hatziefremidis
TZTheodore Zahariadis
Theodore Zahariadis
The recent advancements in the fields of artificial intelligence (AI) and machine learning (ML) have affected several research fields, leading to improvements that could not have been possible with conventional optimization techniques. Among the sectors where AI/ML enables a plethora of opportunities, industrial manufacturing can expect significant gains from the increased process automation. At the same time, the introduction of the Industrial Internet of Things (IIoT), providing improved wireless connectivity for real-time manufacturing data collection and processing, has resulted in the culmination of the fourth industrial revolution, also known as Industry 4.0. In this survey, we focus on the vital processes of fault detection, prediction and prevention in Industry 4.0 and present recent developments in ML-based solutions. We start by examining various proposed cloud/fog/edge architectures, highlighting their importance for acquiring manufacturing data in order to train the ML algorithms. In addition, as faults might also occur from sources beyond machine degradation, the potential of ML in safeguarding cyber-security is thoroughly discussed. Moreover, a major concern in the Industry 4.0 ecosystem is the role of human operators and workers. Towards this end, a detailed overview of ML-based human–machine interaction techniques is provided, allowing humans to be in-the-loop of the manufacturing processes in a symbiotic manner with minimal errors. Finally, open issues in these relevant fields are given, stimulating further research.

14 September 2021 in Information
Verified
Journal Article
Open access
PDF file
SBStavroula Bourou
Stavroula Bourou
ASAndreas El Saer
Andreas El Saer
TVTerpsichori-Eleni Velivassaki
Terpsichori-Eleni Velivassaki
AVArtemis Voulkidis
Artemis Voulkidis
TZTheodore Zahariadis
Theodore Zahariadis
Recent technological innovations along with the vast amount of available data worldwide have led to the rise of cyberattacks against network systems. Intrusion Detection Systems (IDS) play a crucial role as a defense mechanism in networks against adversarial attackers. Machine Learning methods provide various cybersecurity tools. However, these methods require plenty of data to be trained efficiently, which may be hard to collect or to use due to privacy reasons. One of the most notable Machine Learning tools is the Generative Adversarial Network (GAN), and it has great potential for tabular data synthesis. In this work, we start by briefly presenting the most popular GAN architectures, VanillaGAN, WGAN, and WGAN-GP. Focusing on tabular data generation, CTGAN, CopulaGAN, and TableGAN models are used for the creation of synthetic IDS data. Specifically, the models are trained and evaluated on an NSL-KDD dataset, considering the limitations and requirements that this procedure needs. Finally, based on certain quantitative and qualitative methods, we argue and evaluate the most prominent GANs for tabular network data synthesis.

19 May 2021 in Information
Verified
Journal Article
Open access
PDF file
KFKonstantina Fotiadou
Konstantina Fotiadou
TVTerpsichori-Eleni Velivassaki
Terpsichori-Eleni Velivassaki
AVArtemis Voulkidis
Artemis Voulkidis
DSDimitrios Skias
Dimitrios Skias
STSofia Tsekeridou
Sofia Tsekeridou
TZTheodore Zahariadis
Theodore Zahariadis
Network intrusion detection is a key pillar towards the sustainability and normal operation of information systems. Complex threat patterns and malicious actors are able to cause severe damages to cyber-systems. In this work, we propose novel Deep Learning formulations for detecting threats and alerts on network logs that were acquired by pfSense, an open-source software that acts as firewall on FreeBSD operating system. pfSense integrates several powerful security services such as firewall, URL filtering, and virtual private networking among others. The main goal of this study is to analyse the logs that were acquired by a local installation of pfSense software, in order to provide a powerful and efficient solution that controls traffic flow based on patterns that are automatically learnt via the proposed, challenging DL architectures. For this purpose, we exploit the Convolutional Neural Networks (CNNs), and the Long Short Term Memory Networks (LSTMs) in order to construct robust multi-class classifiers, able to assign each new network log instance that reaches our system into its corresponding category. The performance of our scheme is evaluated by conducting several quantitative experiments, and by comparing to state-of-the-art formulations.

23 December 2019 in Clean Technologies
Verified
Journal Article
Open access
PDF file
TSTheodoros A. Skouras
Theodoros A. Skouras
Panagiotis GkonisPanagiotis Gkonis
Panagiotis Gkonis
CICharalampos N. Ilias
Charalampos N. Ilias
PTPanagiotis Trakadas
Panagiotis Trakadas
TTTsampasis Tsampasis
Tsampasis Tsampasis
TZTheodore Zahariadis
Theodore Zahariadis
The goal of the study presented in this article is to provide a general overview of the various aspects related to electric vehicles (EVs), along with all associated emerging challenges and perspectives. In this context, the basic types of EVs and the corresponding charging technologies are analyzed. Since EVs are expected to be a key component of future smart electrical grids (SEG), connection to the grid issues, along with advanced charging techniques (i.e., wireless power transfer), are analyzed as well. To this end, the main features, the requirements of vehicle to grid (V2G) communications, as well as future developments and scenarios of electrification, are also presented and analyzed. Moreover, integration issues with currently deployed fifth generation (5G) mobile wireless networks are also outlined, in order to ensure optimum transmission and reception quality in V2G communications and improved user experience. This integration is also expanded in autonomous vehicles (AVs) technology (self-driving objects), since optimized information processing from various diverse sources is required in order to ensure advanced traffic management aspects.

17 August 2019 in Sensors
Verified
Journal Article
Open access
PDF file
PTPanagiotis Trakadas
Panagiotis Trakadas
Nikolaos NomikosNikolaos Nomikos
Nikolaos Nomikos
Emmanouel T. MichailidisEmmanouel T. Michailidis
Emmanouel T. Michailidis
TZTheodore Zahariadis
Theodore Zahariadis
FFFederico M. Facca
Federico M. Facca
Panagiotis GkonisPanagiotis Gkonis
Panagiotis Gkonis
Hybrid cloud multi-access edge computing (MEC) deployments have been proposed as efficient means to support Internet of Things (IoT) applications, relying on a plethora of nodes and data. In this paper, an overview on the area of hybrid clouds considering relevant research areas is given, providing technologies and mechanisms for the formation of such MEC deployments, as well as emphasizing several key issues that should be tackled by novel approaches, especially under the 5G paradigm. Furthermore, a decentralized hybrid cloud MEC architecture, resulting in a Platform-as-a-Service (PaaS) is proposed and its main building blocks and layers are thoroughly described. Aiming to offer a broad perspective on the business potential of such a platform, the stakeholder ecosystem is also analyzed. Finally, two use cases in the context of smart cities and mobile health are presented, aimed at showing how the proposed PaaS enables the development of respective IoT applications.

Verified
Journal Article
Open access
PDF file
PTPanagiotis Trakadas
Panagiotis Trakadas
Panagiotis KarkazisPanagiotis Karkazis
Panagiotis Karkazis
HLHelen Leligou
Helen Leligou
TZTheodore Zahariadis
Theodore Zahariadis
FVFelipe Vicens
Felipe Vicens
Dimosthenis KyriazisDimosthenis Kyriazis
Dimosthenis Kyriazis
5G is considered to be the technology that will accommodate the development and management of innovative services with stringent and diverse requirements from end users, calling for new business models from the industry. In this context, the development and efficient management of Network Services (NS) serving specific vertical industries and spanning across multiple administrative domains and heterogeneous infrastructures is challenging. The main challenges regard the efficient provision of NSs considering the Quality of Service (QoS) requirements per vertical industry along with the optimal usage of the allocated resources. Towards addressing these challenges, this paper details an innovative approach that we have developed for managing and orchestrating such NSs, called SONATA, and compare it with OSM and Cloudify, which are two of the most known open-source Management and Orchestration (MANO) frameworks. In addition to examining the supported orchestration mechanisms per MANO framework, an evaluation of main operational and functional KPIs is provided based on experimentation using a real testbed. The final aim is the identification of their strong and weak points, and the assessment of their suitability for serving diverse vertical industry needs, including of course the Internet of Things (IoT) service ecosystem.