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Authors = Michael Chrysostomou ORCID = 0000-0003-2750-3209

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18 pages, 5237 KiB  
Article
Reliable IoT-Based Monitoring and Control of Hydroponic Systems
by Konstantinos Tatas, Ahmad Al-Zoubi, Nicholas Christofides, Chrysostomos Zannettis, Michael Chrysostomou, Stavros Panteli and Anthony Antoniou
Technologies 2022, 10(1), 26; https://doi.org/10.3390/technologies10010026 - 2 Feb 2022
Cited by 50 | Viewed by 18872
Abstract
This paper presents the design and implementation of iPONICS: an intelligent, low-cost IoT-based control and monitoring system for hydroponics greenhouses. The system is based on three types of sensor nodes. The main (master) node is responsible for controlling the pump, monitoring the quality [...] Read more.
This paper presents the design and implementation of iPONICS: an intelligent, low-cost IoT-based control and monitoring system for hydroponics greenhouses. The system is based on three types of sensor nodes. The main (master) node is responsible for controlling the pump, monitoring the quality of the water in the greenhouse and aggregating and transmitting the data from the slave nodes. Environment sensing slave nodes monitor the ambient conditions in the greenhouse and transmit the data to the main node. Security nodes monitor activity (movement in the area). The system monitors water quality and greenhouse temperature and humidity, ensuring that crops grow under optimal conditions according to hydroponics guidelines. Remote monitoring for the greenhouse keepers is facilitated by monitoring these parameters via connecting to a website. An innovative fuzzy inference engine determines the plant irrigation duration. The system is optimized for low power consumption in order to facilitate off-grid operation. Preliminary reliability analysis indicates that the system can tolerate various transient faults without requiring intervention. Full article
(This article belongs to the Special Issue MOCAST 2021)
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18 pages, 2981 KiB  
Article
Stable Isotope and Radiocarbon Analysis for Diet, Climate and Mobility Reconstruction in Agras (Early Iron Age) and Edessa (Roman Age), Northern Greece
by Elissavet Dotsika, Maria Tassi, Petros Karalis, Anastasia Chrysostomou, Dimitra Ermioni Michael, Anastasia Elektra Poutouki, Katerina Theodorakopoulou and Georgios Diamantopoulos
Appl. Sci. 2022, 12(1), 498; https://doi.org/10.3390/app12010498 - 5 Jan 2022
Cited by 3 | Viewed by 3256
Abstract
In this article we present an isotopic analysis of human bone collagen (δ13Ccol, and δ15Ncol) and bone apatite (δ13C) for diet reconstruction, as well as δ18Oap of human bone apatite [...] Read more.
In this article we present an isotopic analysis of human bone collagen (δ13Ccol, and δ15Ncol) and bone apatite (δ13C) for diet reconstruction, as well as δ18Oap of human bone apatite for climate reconstruction, using samples from Northern Greece. Radiocarbon dating analysis was conducted on three of the Agras samples and the results (from 1000 to 800 BC) correspond to the Early Iron Age. Isotopic values for δ13Ccol range from −20.5‰ to −16‰ and for δ15Ncol from 6‰ to 11.1‰—a strong indication of a C3-based diet, with contributions by C4 and freshwater fish elements. The results were compared to the ones from Roman Edessa, and Alexandreia (a contemporary city near Edessa), as well as to other Early Iron sites in Greece and wider Europe. In general, the results from Agras are in good agreement with the results from Northern Greece, with the exception of the Makriyalos site, and are quite close to those of Croatia’s and Hungary’s sites. Additionally, from the δ18Oap results we calculated the oxygen isotopic composition of consumed water for Agras (from −9.6‰ to −10.9‰) and for Roman Edessa (from −9.6‰ to −11.2‰) for the palaeoclimate and palaeomobility reconstruction. Full article
(This article belongs to the Special Issue Material and Environmental Isotope Geochemistry)
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18 pages, 5000 KiB  
Article
Multicell Power Supplies for Improved Energy Efficiency in the Information and Communications Technology Infrastructures
by Michael Chrysostomou, Nicholas Christofides, Stelios Ioannou and Alexis Polycarpou
Energies 2021, 14(21), 7038; https://doi.org/10.3390/en14217038 - 27 Oct 2021
Cited by 2 | Viewed by 2374
Abstract
The rapid growth of the Information and Communications Technology (ICT) sector requires additional infrastructure, such as more micro-datacenters and telecom stations, to support the higher internet speeds and low latency requirements of 5G networks. The increased power requirements of the new ICT technologies [...] Read more.
The rapid growth of the Information and Communications Technology (ICT) sector requires additional infrastructure, such as more micro-datacenters and telecom stations, to support the higher internet speeds and low latency requirements of 5G networks. The increased power requirements of the new ICT technologies necessitate the proposal of new power supplies, in an attempt to support the increase in energy demand and running costs. This work provides an in-depth theoretical analysis on the losses of the individual stages of commercially available PSU and proposes a new multicell PSU, the buck PFC converter, which offers a higher overall efficiency at varying load levels. The theoretical results are verified using simulation results, via a PSIM Thermal Module, and using experimental data. The results indicate that multicell structures can improve the overall PSU efficiency by 1.2% at 50% rated power and more than 2.1% at full power. Finally, taking into consideration the economic implications of this study, it is shown that the proposed multicell structure may increase the PSU costs by 10.78%, but the payback period is in the order of just 3.3 years. Full article
(This article belongs to the Topic Application of Innovative Power Electronic Technologies)
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