arXiv subjects

Yiannis Kiouvrekis

Publications and source records attributed to Yiannis Kiouvrekis.

2 recordsLinked to original sources

arXiv2023

Domain preserving and strongly converging explicit scheme for the stochastic SIS epidemic model

In this article, we construct a numerical method for a stochastic version of the Susceptible Infected Susceptible (SIS) epidemic model, expressed by a suitable stochastic differential equation (SDE), by using the semi-discrete method to a suitable transformed process. We prove the strong convergence of the proposed method, with order $1,$ and examine its stability properties. Since SDEs generally lack analytical solutions, numerical techniques are commonly employed. Hence, the research will seek numerical solutions for existing stochastic models by constructing suitable numerical schemes and comparing them with other schemes. The objective is to achieve a qualitative and efficient approach to solving the equations. Additionally, for models that have not yet been proposed for stochastic modeling using SDEs, the research will formulate them appropriately, conduct theoretical analysis of the model properties, and subsequently solve the corresponding SDEs.

math.NA↗

arXiv2020

Unsupervised Machine Learning and EMF radiation in schools: a study of 205 schools in Greece

The expansion of network infrastructure in Greece has raised concerns about the possible negative health effects on sensitive groups, such as children, from exposure to long-term radiofrequency electromagnetic fields (RF-EMFs). The objective of this study is to apply Unsupervised Machine Learning methods such as hierarchical clustering, in order to establish patterns of EMF radiation in schools. To this end we performed measurements in the majority schools units in the region of Thessaly in order to calculate the mean value for RF - EMF exposure in the 27 MHz - 3 GHz range, which covers the whole spectrum of RF - EMF sources. Hierarchical clustering dendrogram analysis shows that population density in urban areas of Thessaly bears no relation to the level of EMF exposure in schools. Furthermore, in $97.5\%$ of schools found in the Thessaly region, the exposure level is at least 3500 times below the Greek exposure limits while in $2.5\%$ it is a little less than 500 times below the limit.

physics.med-ph↗