Evangelos Karakolis

Mr. Evangelos Karakolis

National Technical University of Athens, Athens, Attikí, Greece
orcid

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

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

Representative Publications

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15 September 2023 in Sustainable Energy, Grids and Networks
Verified
Journal Article
Open access
SPSotiris Pelekis
Sotiris Pelekis
ISIoannis-Konstantinos Seisopoulos
Ioannis-Konstantinos Seisopoulos
ESEvangelos Spiliotis
Evangelos Spiliotis
TPTheodosios Pountridis
Theodosios Pountridis
EKEvangelos Karakolis
Evangelos Karakolis
DADimitrios Askounis
Dimitrios Askounis

15 July 2022 in Applied Sciences
Verified
Journal Article
Open access
PDF file
EKEvangelos Karakolis
Evangelos Karakolis
Panagiotis KapsalisPanagiotis Kapsalis
Panagiotis Kapsalis
SSStavros Skalidakis
Stavros Skalidakis
CKChristos Kontzinos
Christos Kontzinos
PKPanagiotis Kokkinakos
Panagiotis Kokkinakos
DADimitrios Askounis
Dimitrios Askounis
In the 21st century, technology evolves extremely fast. The same applies to technology-related professions, mostly in terms of skills requirements. Contradictorily, higher education technological institutions are not always in the position to keep up with the labor market requirements. As a result, some of the skills taught in their courses are oftentimes outdated. From a learner’s perspective, the main goal should be to avoid such outdated courses, as for most university students, the long-term objective is to land a job, where they will utilize the skills they acquired from their studies. On the other hand, from an educational decision maker’s perspective, the most important goal is to keep up with the changes in the labor market, offering courses that will be valuable for the prospective careers of students. The work conducted in the context of this publication aims to bridge the gap between education offered in universities and job market skills’ requirements in technology. Specifically, a skill and course recommender system was developed to help learners select courses that are valuable for the job market, as well as a curriculum design service, which recommends updates to a given curriculum based on the job market needs. Both services are built on top of a text mining service that retrieves job posts from several online sources and performs skill extraction from them based on text analytics techniques. Moreover, a decision support service was developed to facilitate optimal decisions for both learners and education decision makers. All services were evaluated positively by 31 early users.

21 December 2023 in Mathematics
Verified
Journal Article
Open access
PDF file
ATALEXANDROS MENELAOS TZORTZIS
ALEXANDROS MENELAOS TZORTZIS
SPSotiris Pelekis
Sotiris Pelekis
ESEvangelos Spiliotis
Evangelos Spiliotis
EKEvangelos Karakolis
Evangelos Karakolis
SMSpiros Mouzakitis
Spiros Mouzakitis
DADimitrios Askounis
Dimitrios Askounis
Short-term load forecasting (STLF) is crucial for the daily operation of power grids. However, the non-linearity, non-stationarity, and randomness characterizing electricity demand time series renders STLF a challenging task. Various forecasting approaches have been proposed for improving STLF, including neural network (NN) models which are trained using data from multiple electricity demand series that may not necessarily include the target series. In the present study, we investigate the performance of a special case of STLF, namely transfer learning (TL), by considering a set of 27 time series that represent the national day-ahead electricity demand of indicative European countries. We employ a popular and easy-to-implement feed-forward NN model and perform a clustering analysis to identify similar patterns among the load series and enhance TL. In this context, two different TL approaches, with and without the clustering step, are compiled and compared against each other as well as a typical NN training setup. Our results demonstrate that TL can outperform the conventional approach, especially when clustering techniques are considered.

14 May 2022 in Applied Sciences
Verified
Journal Article
Open access
PDF file
EKEvangelos Karakolis
Evangelos Karakolis
PKPanagiotis Kokkinakos
Panagiotis Kokkinakos
DADimitrios Askounis
Dimitrios Askounis
Nowadays, recommender systems (RS) are no longer evaluated only for the accuracy of their recommendations. Instead, there is a requirement for other metrics (e.g., coverage, diversity, serendipity) to be taken into account as well. In this context, the multi-stakeholder RS paradigm (MSRS) has gained significant popularity, as it takes into consideration all beneficiaries involved, from item providers to simple users. In this paper, the goal is to provide fair recommendations across item providers in terms of diversity and coverage for users to whom each provider’s items are recommended. This is achieved by following the methodology provided by the literature for solving the recommendation problem as an optimization problem under constraints for coverage and diversity. As the constraints for diversity are quadratic and cannot be solved in sufficient time (NP-Hard problem), we propose a heuristic approach that provides solutions very close to the optimal one, as the proposed approach in the literature for solving diversity constraints was too generic. As a next step, we evaluate the results and identify several weaknesses in the problem formulation as provided in the literature. To this end, we introduce new formulations for diversity and provide a new heuristic approach for the solution of the new optimization problem.

14 June 2024 in Applied Sciences
Verified
Journal Article
Open access
PDF file
CKChristos Kontzinos
Christos Kontzinos
EKEvangelos Karakolis
Evangelos Karakolis
PKPanagiotis Kokkinakos
Panagiotis Kokkinakos
SSStavros Skalidakis
Stavros Skalidakis
DADimitrios Askounis
Dimitrios Askounis
John PsarrasJohn Psarras
John Psarras
Since its conceptualization in 2008, blockchain technology has advanced rapidly and been applied in multiple domains. In higher education, blockchain can be applied to develop ICT systems that can revolutionize student accreditation through certificate verification and micro-accreditations, which represent skills and other learning outcomes, in the form of digital/smart badges. While there are multiple studies that highlight the significance of blockchain in higher education and propose digital systems, few of those studies include the evaluation of such proposed systems by real users. As such, the research question of how useful a higher education blockchain system would be for its relevant stakeholders remains largely unanswered. In the research publication at hand, a blockchain-powered higher education platform was applied in the School of Electrical and Computer Engineering of the National Technical University of Athens, where it was used and evaluated by students and professors at the school. The evaluation of the platform was positive, and participants found that the smart badge functionality was among the most useful. Finally, the execution and evaluation of the pilot led to several lessons learned and policy recommendations towards dealing with existing barriers and further promoting blockchain in higher education.

24 June 2024
Verified
Conference Paper
Closed access
SPSotiris Pelekis
Sotiris Pelekis
EKEvangelos Karakolis
Evangelos Karakolis
GLGeorge Lampropoulos
George Lampropoulos
SMSpiros Mouzakitis
Spiros Mouzakitis
OMOurania Markaki
Ourania Markaki
DADimitrios Askounis
Dimitrios Askounis
The present study aims to evaluate the current fuzzy landscape of Trustworthy AI (TAl) within the European Union (EU), with a specific focus on the energy sector. The analysis encompasses legal frameworks, directives, initiatives, and standards like the AI Ethics Guidelines for Trustworthy AI (EGTAI), the Assessment List for Trustworthy AI (ALTAI), the AI act, and relevant CEN-CENELEC standardization efforts, as well as EU-funded projects such as AI4EU and SHERPA. Subsequently, we introduce a new TAl application framework, called E-TAl, tailored for energy applications, including smart grid and smart building systems. This framework draws inspi-ration from EGTAI but is customized for AI systems in the energy domain. It is designed for stakeholders in electrical power and energy systems (EPES), including researchers, developers, and energy experts linked to transmission system operators, distribution system operators, utilities, and aggregators. These stakeholders can utilize E-TAl to develop and evaluate AI services for the energy sector with a focus on ensuring trustworthiness throughout their development and iterative assessment processes.