Vassilis C. Gerogiannis

Prof. Vassilis C. Gerogiannis

Department of Digital Systems, University of Thessaly, Larissa, Greece
orcid

Research Focus & Metrics

Academic Career Length

32Years (1995-Present)

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

Representative Publications

View All Publications
19 June 2023 in Sensors
Verified
Journal Article
Open access
PDF file
CMCheena Mohanty
Cheena Mohanty
SMSakuntala Mahapatra
Sakuntala Mahapatra
BABiswaranjan Acharya
Biswaranjan Acharya
Fotis KokkorasFotis Kokkoras
Fotis Kokkoras
Vassilis C. GerogiannisVassilis C. Gerogiannis
Vassilis C. Gerogiannis
Andreas KanavosAndreas Kanavos
Andreas Kanavos
Diabetic retinopathy (DR) is a common complication of long-term diabetes, affecting the human eye and potentially leading to permanent blindness. The early detection of DR is crucial for effective treatment, as symptoms often manifest in later stages. The manual grading of retinal images is time-consuming, prone to errors, and lacks patient-friendliness. In this study, we propose two deep learning (DL) architectures, a hybrid network combining VGG16 and XGBoost Classifier, and the DenseNet 121 network, for DR detection and classification. To evaluate the two DL models, we preprocessed a collection of retinal images obtained from the APTOS 2019 Blindness Detection Kaggle Dataset. This dataset exhibits an imbalanced image class distribution, which we addressed through appropriate balancing techniques. The performance of the considered models was assessed in terms of accuracy. The results showed that the hybrid network achieved an accuracy of 79.50%, while the DenseNet 121 model achieved an accuracy of 97.30%. Furthermore, a comparative analysis with existing methods utilizing the same dataset revealed the superior performance of the DenseNet 121 network. The findings of this study demonstrate the potential of DL architectures for the early detection and classification of DR. The superior performance of the DenseNet 121 model highlights its effectiveness in this domain. The implementation of such automated methods can significantly improve the efficiency and accuracy of DR diagnosis, benefiting both healthcare providers and patients.

13 July 2010 in Quality Assurance in Education
Verified
Journal Article
Closed access
MTMaria Tsinidou
Maria Tsinidou
Vassilis C. GerogiannisVassilis C. Gerogiannis
Vassilis C. Gerogiannis
PFPanos Fitsilis
Panos Fitsilis
Purpose: The aim of this paper is to identify the quality determinants for education services provided by higher education institutions (HEIs) in Greece and to measure their relative importance from the students' points of view.Design/mthodology/approach: A multi‐criteria decision‐making methodology was used for assessing the relative importance of quality determinants that affect student satisfaction. More specifically, the analytical hierarchical process (AHP) was used in order to measure the relative weight of each quality factor.Findings: The relative weights of the factors that contribute to the quality of educational services as it is perceived by students was measured.Research limitations/implications: The research is based on the questionnaire of the Hellenic Quality Assurance Agency for Higher Education. This implies that the measured weights are related mainly to questions posed in this questionnaire. However, the applied method (AHP) can be used to assess different quality determinants.Practical implications: The outcome of this study can be used in order to quantify internal quality assessment of HEIs. More specifically, the outcome can be directly used by HEIs for assessing quality as perceived by students.Originality/value: The paper attempts to develop insights into comparative evaluations of quality determinants as they are perceived by students.

25 June 2020 in Education and Information Technologies
Verified
Journal Article
Closed access
PDF file
Omiros IatrellisOmiros Iatrellis
Omiros Iatrellis
ISIlias Κ. Savvas
Ilias Κ. Savvas
PFPanos Fitsilis
Panos Fitsilis
Vassilis C. GerogiannisVassilis C. Gerogiannis
Vassilis C. Gerogiannis

1 January 2023 in Electronics
Verified
Journal Article
Open access
PDF file
DSDebabrata Swain
Debabrata Swain
UMUtsav Mehta
Utsav Mehta
ABAyush Bhatt
Ayush Bhatt
HPHardeep Patel
Hardeep Patel
KPKevin Patel
Kevin Patel
SMStella Manika
Stella Manika
Clinical support systems are affected by the issue of high variance in terms of chronic disorder prognosis. This uncertainty is one of the principal causes for the demise of large populations around the world suffering from some fatal diseases such as chronic kidney disease (CKD). Due to this reason, the diagnosis of this disease is of great concern for healthcare systems. In such a case, machine learning can be used as an effective tool to reduce the randomness in clinical decision making. Conventional methods for the detection of chronic kidney disease are not always accurate because of their high degree of dependency on several sets of biological attributes. Machine learning is the process of training a machine using a vast collection of historical data for the purpose of intelligent classification. This work aims at developing a machine-learning model that can use a publicly available data to forecast the occurrence of chronic kidney disease. A set of data preprocessing steps were performed on this dataset in order to construct a generic model. This set of steps includes the appropriate imputation of missing data points, along with the balancing of data using the SMOTE algorithm and the scaling of the features. A statistical technique, namely, the chi-squared test, is used for the extraction of the least-required set of adequate and highly correlated features to the output. For the model training, a stack of supervised-learning techniques is used for the development of a robust machine-learning model. Out of all the applied learning techniques, support vector machine (SVM) and random forest (RF) achieved the lowest false-negative rates and test accuracy, equal to 99.33% and 98.67%, respectively. However, SVM achieved better results than RF did when validated with 10-fold cross-validation.

1 May 2021 in Big Data Research
Verified
Journal Article
Open access
FLFatima Leal
Fatima Leal
ACAdriana E. Chis
Adriana E. Chis
SCSimon Caton
Simon Caton
Horacio González-VélezHoracio González-Vélez
Horacio González-Vélez
JGJuan Miguel Garcia-Gomez
Juan Miguel Garcia-Gomez
MMMariola Mier
Mariola Mier

7 December 2020 in Complex & Intelligent Systems
Verified
Journal Article
Open access
PDF file
JCJia Syuen Chai
Jia Syuen Chai
GSGaneshsree Selvachandran
Ganeshsree Selvachandran
Florentin SmarandacheFlorentin Smarandache
Florentin Smarandache
Vassilis C. GerogiannisVassilis C. Gerogiannis
Vassilis C. Gerogiannis
LSLe Hoang Son
Le Hoang Son
BVBay Vo
Bay Vo
The single-valued neutrosophic set (SVNS) is a well-known model for handling uncertain and indeterminate information. Information measures such as distance measures, similarity measures and entropy measures are very useful tools to be used in many applications such as multi-criteria decision making (MCDM), medical diagnosis, pattern recognition and clustering problems. A lot of such information measures have been proposed for the SVNS model. However, many of these measures have inherent problems that prevent them from producing reasonable or consistent results to the decision makers. In this paper, we propose several new distance and similarity measures for the SVNS model. The proposed measures have been verified and proven to comply with the axiomatic definition of the distance and similarity measure for the SVNS model. A detailed and comprehensive comparative analysis between the proposed similarity measures and other well-known existing similarity measures has been done. Based on the comparison results, it is clearly proven that the proposed similarity measures are able to overcome the shortcomings that are inherent in existing similarity measures. Finally, an extensive set of numerical examples, related to pattern recognition and medical diagnosis, is given to demonstrate the practical applicability of the proposed similarity measures. In all numerical examples, it is proven that the proposed similarity measures are able to produce accurate and reasonable results. To further verify the superiority of the suggested similarity measures, the Spearman’s rank correlation coefficient test is performed on the ranking results that were obtained from the numerical examples, and it was again proven that the proposed similarity measures produced the most consistent ranking results compared to other existing similarity measures.