Investigation of high renewable energy penetration in the island of Syros following the interconnection with the national grid system

This paper aims to assess the potential of high renewable energy (wind and solar) integration in the Greek island of Syros, following the scheduled interconnection with the national grid system. Currently, Syros operates an oil fired autonomous power system (APS), emitting large amounts of carbon emissions. Interconnection among a number of islands in the Cyclades and the mainland will eliminate the use of APS, will reinforce islands’ power network and will allow exploitation of high wind and solar potential. It has been concluded that following the interconnection, the installation of 33.5 MW of wind and solar energy is feasible. The assumed capacity will cover the total energy demand by 2030 allowing also electricity exports to the Greek mainland. Transforming Syros into a regional renewable energy hub will contribute to the energy security, providing access to its own energy resources

An AHP (Analytic Hierarchy Process)/ANP (Analytic Network Process)-based multi- criteria decision approach for the selection of solar-thermal power plant investment projects

In this paper the AHP (Analytic Hierarchy Process) and the ANP (Analytic Network Process) are applied to help the managing board of an important Spanish solar power investment company to decide whether to invest in a particular solar-thermal power plant project and, if so, to determine the order of priority of the projects in the company's portfolio. Project management goes through a long process, from obtaining the required construction permits and authorizations, negotiating with different stakeholders, complying with complex legal regulations, to solving the technical problems associated with plant construction and distribution of the energy generated. The whole process involves high engineering costs. The decision approach proposed in this paper consists of three phases. In the first two phases, the managing board must decide whether to accept or reject a project according to a set of criteria previously identified by the technical team. The third phase consists of establishing a priority order among the projects that have proven to be economically profitable based on project risk levels and execution time delays. This work analyzes the criteria that should be taken into account to accept or reject proposals for investment, as well as the risks used to prioritize some projects over others.The translation of this paper has been funded by the Universitat Politecnica de Valencia.Aragonés Beltrán, P.; Chaparro González, FV.; Pastor Ferrando, JP.; Pla Rubio, A. (2014). An AHP (Analytic Hierarchy Process)/ANP (Analytic Network Process)-based multi- criteria decision approach for the selection of solar-thermal power plant investment projects. Energy. 66:222-238. doi:10.1016/j.energy.2013.12.016S2222386

Framework for strategic wind farm site prioritisation based on modelled wolf reproduction habitat in Croatia

In order to meet carbon reduction targets, many nations are greatly expanding their wind power capacity. However, wind farm infrastructure potentially harms wildlife, and we must therefore find ways to balance clean energy demands with the need to protect wildlife. Wide-ranging carnivores live at low density and are particularly susceptible to disturbance from infrastructure development, so are a particular concern in this respect. We focused on Croatia, which holds an important population of wolves and is currently planning to construct many new wind farms. Specifically, we sought to identify an optimal subset of planned wind farms that would meet energy targets while minimising potential impact on wolves. A suitability model for wolf breeding habitat was carried out using Maxent, based on six environmental variables and 31 reproduction site locations collected between 1997 and 2015. Wind farms were prioritised using Marxan to find the optimal trade-off between energy capacity and overlap with critical wolf reproduction habitat. The habitat suitability model predictions were consistent with the current knowledge: probability of wolf breeding site presence increased with distance to settlements, distance to farmland and distance to roads and decreased with distance to forest. Spatial optimisation showed that it would be possible to meet current energy targets with only 31% of currently proposed wind farms, selected in a way that reduces the potential ecological cost (overall predicted wolf breeding site presence within wind farm sites) by 91%. This is a highly efficient outcome, demonstrating the value of this approach for prioritising infrastructure development based on its potential impact on wide-ranging wildlife species

Light-based technologies for management of COVID-19 pandemic crisis.

The global dissemination of the novel coronavirus disease (COVID-19) has accelerated the need for the implementation of effective antimicrobial strategies to target the causative agent SARS-CoV-2. Light-based technologies have a demonstrable broad range of activity over standard chemotherapeutic antimicrobials and conventional disinfectants, negligible emergence of resistance, and the capability to modulate the host immune response. This perspective article identifies the benefits, challenges, and pitfalls of repurposing light-based strategies to combat the emergence of COVID-19 pandemic

1. Axos, a Cretan City (1200-500 BC)

For decades, archaeological research in Crete focused on the study of the Bronze Age identified with Minoan civilisation. In recent years, however, attention has been swinging back to issues associated with the period following the collapse of Minoan civilisation, and the social, economic and political processes that led to the creation of the political institution of the city-state, which was preserved until the Roman conquest (Gehrke 1997; Chaniotis 2004: 51-78, 100-104). These efforts have..

Marrow-Isolated Adult Multilineage Inducible (MIAMI) and Annulus Fibrosus Cell Co-Cultures on Electrospun Polycaprolactone Scaffolds for Intervertebral Disc Tissue Engineering

Back pain affects more than 80% of the adult population between the ages of 45- 54 years old, and it is a leading cause of disabilities in developing countries. For the most part, low back pain is associated with degeneration of the intervertebral disc (IVD) called degenerative disc disorder (DDD) or degenerative IVD disorder (IDD). Current treatment options are all symptomatic and lead to further degeneration of adjacent vertebrae. Although tissue engineering approaches show potential for treatment of DDD, IVD cells are not readily available, rendering their use for implantation difficult. This study focuses on the use of marrow-isolated adult multilineage inducible (MIAMI) cells co-cultured together with native annulus fibrosus (AF) cells as alternative source for IVD tissue engineering. Moreover, the paper proposes the use of electrospun, polycaprolactone (PCL) scaffolds as substrates for the culture of the cells. The hypothesis was that co-culturing AF and MIAMI cells on PCL scaffolds would lead to differentiation of the latter ones into native disc lineages effectively. PCL scaffolds with random fiber orientation were fabricated using different solvents (DCM and HFIP) and polymer concentrations (12%, 15% and 20%). Scaffolds were characterized using scanning electron microscopy (SEM) for their fiber diameter and uniformity. PCL/HFIP constructs possessed superior properties, with uniform fibers and diameters of 0.88±0.27, 0.94±0.35, and 2.07±0.18μm for 12%, 15% and 20% scaffolds respectively. Porcine AF and MIAMI cells were obtained and co-cultured on scaffolds for 1, 2 and 3 weeks, by which time samples were obtained for RT-PCR. Cells were tested for the expression of markers Col I, II, Acan, as well as Oct-4 and Nanog. AF cells alone were also seeded on tissue culture plates and their ability to differentiate into osteogenic lineages was studied through the addition of osteogenic media. Cells on the scaffolds did not yield consistent Ct values after PCR, however, co-cultured cells seeded on scaffolds for three weeks had distinct expression of Col 1 and Acan, with a significant increase of Col 1 compared to MIAMI-only controls. AF that underwent osteogenesis tested positive for osteogenic markers Alk-P, Osteocalcin and Osterix unlike the AF controls (normal culture), which tested negative

Analytical and experimental investigation on the seismic efficiency of a new type of abutment for limiting the seismic movements of the bridge deck

The aim of this study is the analytical and experimental investigation on the seismicefficiency of an innovative restraining system. This system consists of transverselydirected R/C walls, which behave as seismic stoppers. The aforementioned wallsconstitute part of the abutment and they are transversely directed to thelongitudinal direction of the bridge. The walls are constructed in a concrete boxshapedsubstructure, which replaces the conventional wing-walls and retains thebackfill material. Therefore, the earth pressures affect only the stability of theconcrete box-shaped substructure and the abutment’s foundation, and not theearthquake resistance of the restraining walls. The expansion joint, which exists inconventional abutments, is eliminated, while only a road joint is preserved betweenthe continuity slab and the road surface, constructed on a sliding body. The designof the proposed system follows the capacity design provisions which ensure theavoidance of the early failure of its members.The available height of the abutment and the thickness of the walls are the mainparameters affecting the serviceability level and seismic resistance of theaforementioned system. These parameters are strongly correlated, as they bothinfluence the shear ratio of concrete walls and consequently, the seismic efficiencyof the restraining system. This study investigates the applicability of the proposedrestraining system in all bridge types, independently of their length and theabutment’s available height.The restraining walls of the abutment contribute not only by their own stiffness butalso by dissipating energy through hysteretic behavior. As a result, the proposedabutment should mainly be exploited in ductile bridge systems. In this respect, thisstudy proposes a methodology for the modification of floating deck bridges toductile systems. It is noted that, floating deck bridges are the ones constructedusing the method of segmental erection with precast prestressed Ι-beams and theincremental launching method.The design and optimization of the proposed abutment is also one of the main goalsof the study. The design of the system aiming at the maximization of its seismicefficiency, is based on two criteria referring, on one hand, on the accommodation ofthe in-service induced longitudinal movements of the deck and, on the other hand,on the earthquake loading of the walls. The carried investigation covers the fourmain construction methods of concrete bridges typology related to the finalresisting system of the bridge, namely: (a) cast in-situ bridge construction, (b) segmental erection with precast prestressed Ι-beams, (c) incremental launchingmethod and (d) form traveler method. The main parameters investigated are: (a)bridge type, (b) length of the continuous bridge deck, (c) dimensions, type,longitudinal reinforcement ratio and arrangement of the restraining walls, (d) totalstiffness of the system, (e) foundation soil type and (f) the seismicity of the region.The results of the investigation showed that the proposed restraining systemimproves the safety, durability, serviceability, aesthetics and cost-effectiveness ofbridges. Specifically, the exploitation of the proposed abutment in monolithic andfloating deck bridge systems showed that, the longitudinal and transversemovements of the deck are effectively reduced. The aforementioned reductions inthe seismic movements lead to reduced seismic actions of the piers. It is notedthat, the reduction in the seismic actions leads to cost- effective and smaller crosssectionsof the piers, which also serve aesthetics. Finally, the experimentalinvestigation verified that the capacity of the system to dissipate energy issignificant.Αντικείμενο της παρούσας Διατριβής αποτελεί η αναλυτική και πειραματικήδιερεύνηση επί της αντισεισμικής μηχανικής απόδοσης ενός καινοτόμου μηχανισμούανασχέσεως των σεισμικών μετακινήσεων του φορέα των γεφυρών. Ο μηχανισμόςαυτός συνίσταται από τοιχώματα, τα οποία λειτουργούν ως σεισμικοί ανασχετήρεςεγκατεστημένοι στα ακρόβαθρα και προσανατολισμένοι εγκαρσίως ως προς τονάξονα της γέφυρας. Τα τοιχώματα αυτά βρίσκονται εντός κιβωτίου, το οποίουποκαθιστά τους καθιερωμένους τοίχους αντεπιστροφής, μέσω του οποίουεπιτυγχάνεται η αντιστήριξη και ο διαχωρισμός του μεταβατικού επιχώματος από τουπόλοιπο σύστημα. Κατά συνέπεια, οι ασκούμενες στα τοιχώματα του κιβωτίουωθήσεις των γαιών δεν επηρεάζουν τη σεισμική απόκριση του συστήματος, ωστόσοπρέπει να λαμβάνονται υπόψη κατά τον έλεγχο ευστάθειας του ακροβάθρου. Με τοπροτεινόμενο σύστημα η γέφυρα απαλλάσσεται από τους εσωτερικούς της αρμούςενώ, οι ακραίοι αρμοί, οι οποίοι είναι λειτουργικού και όχι αντισεισμικού εύρους,μεταφέρονται μέσω επεκτάσεων της πλάκας του καταστρώματος πέραν τουπροαναφερθέντος συστήματος και διαμορφώνονται άνωθεν καταλλήλου σώματοςολισθήσεως. Η μελέτη του παραπάνω συστήματος διέπεται από τις αρχές τουικανοτικού σχεδιασμού μέσω του οποίου επιδιώκεται η αποφυγή πρόωρης αστοχίαςτων μελών του.Δύο από τις κύριες παραμέτρους που καθορίζουν την απόκριση του μηχανισμούείναι το διαθέσιμο ύψος των ακροβάθρων αφενός και, το πάχος των τοιχωμάτωναφετέρου. Στα πλαίσια της Διατριβής διερευνάται το πεδίο εφαρμογής τουμηχανισμού, εις τρόπον ώστε να είναι δυνατή η αξιοποίησή του σε όλα ταακρόβαθρα ασχέτως διαθέσιμου ύψους καθώς επίσης και σε όλες τις γέφυρες μικρούκαι μεγάλου μήκους, δεδομένου ότι οι λειτουργικές απαιτήσεις θέτουν περιορισμούςως προς τον καθορισμό των προαναφερθεισών παραμέτρων.Η αντισεισμική συνεισφορά των τοιχωμάτων- ανασχετήρων επιδιώκεται αφενός μενμέσω της δυσκαμψίας τους και αφετέρου, μέσω της απορρόφησης σεισμικήςενέργειας, μέσω της υστερητικής απόκρισης των στοιχείων αυτών. Το γεγονός αυτόσυνεπάγεται την αξιοποίηση του προτεινόμενου αντισεισμικού ακροβάθρου σεπλάστιμα, βάσει των απαιτήσεων των Κανονισμών, συστήματα. Ως εκ τούτου, σταπλαίσια της παρούσας Διατριβής προτείνεται μεθοδολογία μετάλλαξης των “πλωτών”επί εφεδράνων γεφυρών σε πλάστιμα συστήματα, έτσι ώστε να καθίσταται εφικτή ηαξιοποίηση του προτεινομένου ακροβάθρου και σε αυτά τα συστήματα. Μετά τηνπλάστιμη προσαρμογή του συστήματος είναι δυνατή η ένταξη στα ακρόβαθρα των υπόψη γεφυρών του προτεινόμενου ανασχετικού μηχανισμού. Σημειωτέον ότι, σταπλωτά επί εφεδράνων συστήματα εντάσσονται γέφυρες, οι οποίες έχουνκατασκευαστεί με τις μεθόδους της προκατασκευής και της προώθησης.Στους στόχους της διεξαχθείσας έρευνας εντάσσεται η βελτιστοποίηση τηςμορφολογίας και των διαστάσεων του ακροβάθρου, με σκοπό αφενός μεν τονσυμβιβασμό των οιονεί, αντικρουόμενων, αντισεισμικών και λειτουργικώναπαιτήσεων της γέφυρας και αφετέρου, τη μεγιστοποίηση της αντισεισμικής τουαπόδοσης. Η διεξαχθείσα έρευνα καλύπτει τους τέσσερις συνηθέστερους, βάσει τηςμεθόδου κατασκευής, τύπους γεφυρών, δηλαδή των: (α) χυτών επί τόπου, (β)προκατασκευασμένων, (γ) γεφυρών κατασκευασμένων με τη μέθοδο τηςπροώθησης και (δ) γεφυρών κατασκευασμένων με τη μέθοδο του προωθούμενουικριώματος. Η αναλυτική και πειραματική διερεύνηση καλύπτει ένα ευρύ φάσμαπαραμέτρων που επηρεάζουν τη σεισμική απόκριση των γεφυρών. Οι κύριεςπαράμετροι που ετέθησαν υπό διερεύνηση ήταν: (α) Το είδος των γεφυρών ανάλογαμε την εφαρμοσθείσα μέθοδο κατασκευής του φορέα, (β) το μήκος του συνεχούςκαταστρώματος των γεφυρών, (γ) η μορφολογία, η όπλιση, η διάταξη και το είδοςτων αξιοποιηθέντων σεισμικών ανασχετήρων στα ακρόβαθρα των γεφυρών, (δ) ησυνολική δυσκαμψία του συστήματος, (ε) η κατηγορία του εδάφους θεμελίωσης τηςγέφυρας και (στ) η σεισμικότητα της περιοχής.Τα αποτελέσματα υπήρξαν ιδιαιτέρως ενθαρρυντικά στους τομείς της ασφάλειας, τηςανθεκτικότητας, της λειτουργικότητας, της αισθητικής και προπάντων τηςοικονομικότητας. Συγκεκριμένα, η αξιοποίηση του προτεινόμενου αντισεισμικούακροβάθρου τόσο σε μονολιθικά όσο και σε πλωτά επί εφεδράνων συστήματαγεφυρών έδειξε ότι οδηγεί σε σημαντική μείωση των διαμήκων και εγκαρσίωνμετακινήσεων του φορέα. Οι προαναφερθείσες μειώσεις των σεισμικώνμετακινήσεων οδηγούν σε αντίστοιχη μείωση των εντατικών μεγεθών τωνμεσοβάθρων, γεγονός που οδηγεί σε λεπτότερες και σε αισθητικώς πιο αποδεκτέςδιατομές των μεσοβάθρων. Τέλος, τα πειραματικά αποτελέσματα έδειξαν ότι ηαποσβεστική απόδοση του προτεινόμενου μηχανισμού είναι σημαντική