Spatial and temporal distribution of rainfall and temperature in Macedonia, Greece, over a thirty year period, using GIS

Η αυξημένη ζήτηση και χρήση των υδάτινων πόρων οδήγησε την Ευρωπαϊκή Ένωση στην καθιέρωση της Ευρωπαϊκής κοινοτικής Οδηγίας Πλαίσιο 2000/60 ΕΚ για τα ύδατα, η οποία έχει στόχο την καλύτερη πολιτική διαχείριση των υδάτων από τα κράτη μέλη. Προκειμένου να επιτευχθεί καλύτερη προστασία αλλά και διαχειρισή των υδάτινων πόρων, τα κράτη μέλη πρέπει να εντοπίσουνε και να αναλύσουνε τα ευρωπαϊκά ύδατα σε επίπεδο λεκάνης απορροής. Ο υετός και η θερμοκρασία του αέρα συνδέονται άμεσα και αλληλεπιδρούν με τον υδρολογικό κύκλο και με τους υδάτινους πόρους. Ο στόχος αυτής της μελέτης είναι να παρουσιάσει την χωρική και χρονική κατανομή του υετού και της θερμοκρασίας του αέρα στη Μακεδονία, με τη χρήση λογισμικού Γ.Σ.Π. (ArcMap 9,3). Τα δεδομένα που χρησιμοποιούνται είναι οι ημερήσιες, μηνιαίες και ετήσιες τιμές των παραπάνω παραμέτρων, οι οποίες ανακτήθηκαν από 82 διαφορετικούς μετεωρολογικούς σταθμούς που ανήκουν στο Υπουργείο Αγροτικής Ανάπτυξης και Τροφίμων, και αντιστοιχούν στο χρονικό διάστημα τριάντα χρόνων (1974-2004). Συγκεκριμένα 82 σταθμοί παρείχαν συνεχή δεδομένα ημερήσιου υετού ενώ 43 από τους σταθμούς παρείχαν συνεχή δεδομένα της ημερήσιας θερμοκρασίας του αέρα. Το Ετήσιο Θερμοκρασιακό Εύρος, η θερμική Ηπειρωτικότητα, η μέση ετήσια θερμοκρασία και το μέσο ετήσιο ύψος υετού υπολογίστηκαν, σε κάθε σταθμό, για τα τριάντα χρόνια της εξεταζόμενης περιόδου. Χρησιμοποιήθηκε το λογισμικό GIS   (ArcMap 9.3) για την εφαρμογή μεθόδων χωρικής παρεμβολής, προκειμένου να προσδιοριστούν οι τιμές των παραπάνω παραμέτρων στη Μακεδονία. Ακολούθησε έλεγχος αξιοπιστίας των μεθόδων και η πιο αξιόπιστη μεθοδος χρησιμοποιήθηκε για την δημιουργία χαρτών με τις προαναφερόμενες παραμέτρους. Έπειτα έγινε υπολογισμός της εξατμισοδιαπνοής για όλους τους μετεωρολογικούς σταθμούς με τρεις μεθόδους Thornthwaite, Turc   και   Coutange.Due to increased demand and use of water resources, the European Union has established the (WFD) Water Framework Directive 2000/60 for Community action in the field of water policy. In order to achieve better water protection and management, Member States must identify and analyse European waters, on the basis of individual river basin and district. Precipitation and air temperature are directly related and at the same way interacted to the hydrological cycle and therefore with water resources. The objective on this study is to present the spatial and temporal distribution of precipitation and air temperature in Macedonia, by using GIS software (ArcMap 9.3).  The data used were retrieved from 82 different meteorological stations, which belong to the Ministry of Rural Development and Food, and correspond to the thirty year period (1974-2004); all stations provided continuous daily data of precipitation while 43 of them provided also daily data of temperature. The annual temperature range and the annual total precipitation amount were calculated, at each individual station, for the thirty years of the examined period. By using GIS software and triangular interpolation scheme, the thematic maps of Macedonia for the aforementioned parameters and thermal continentality K were created. Furthermore, possible mean annual evapotranspiration for each meteorological station was estimated by Turc, Coutagne and Thornthwaite algorithms

HYDROGEOCHEMICAL CONDITION OF THE PIKROLIMNI LAKE (KILKIS GREECE)

In order to understand the hydrogeochemical conditions of the basin of Pikrolimni we collected water samples from the borehole in the thermal spa of Pikrolimni and samples of brine and sediments from the lake. We also sampled fresh water of the region. The depth of the borehole in the thermal spa is approximately 250 meters. This water is naturally sparkling, with a metallic aftertaste and a slight organic smell. The samples were taken twice during the year: in summer (8/2002) and in winter (2003). The analytical scheme includes field measurements of temperature, conductivity and pH. Major ions (Na+, K+, Ca2+, Mg2\ CI", Br, S04 2", C03 2", HC03", N03"), F and Br were determined, in laboratory, according to standard analytical methods. Samples were also subjected to isotopie analysis of δ Ο and δ2Η. The results from the chemical analyses of the samples, show that the waters taken from the borehole, are of the type Mg- (Na-Ca)-HCC>3 and the salts of the lake are of the type Na-CI- (CO3-S04). The salts of the lake result from mixing and condensation of the waters which are accumulated in the basin of the lake, and come not only from sources that feed the lake, e.g. waters from borehole, but also from rain water. The waters of these sources are mainly of meteoritic origin and circulate deeply, mixing probably with salt water of deeper and probably of warmer horizons. The latter comes in agreement with the hydrothermal field, which exists in the area. From hydrochemical data, the brines of summer clearly correspond to waters, which have been submitted under high degree of evaporation: they are residual mother solutions before the step of the precipitation of halite. During winter, dilution of brines and dissolution of depositing minerals by fresh water are observed. On the other hand, evaporating conditions are created in the lake during summer

ΔΙΕΡΕΥΝΗΣΗ ΤΩΝ ΥΔΡΟΜΟΡΦΟΛΟΓΙΚΩΝ ΧΑΡΑΚΤΗΡΙΣΤΙΚΩΝ ΣΕ ΕΠΙΠΕΔΟ ΛΕΚΑΝΗΣ ΑΠΟΡΡΟΗΣ, Η ΠΕΡΙΠΤΩΣΗ ΤΟΥ ΤΡΙΠΟΤΑΜΟΥ ΗΜΑΘΙΑΣ

Στην παρούσα εργασία διερευνήθηκαν τα υδρομορφολογικά χαρακτηριστικά του χειμάρρου Τριπόταμου, όπως ορίζονται από την Οδηγία 2000/60/Ε.Κ. Ειδικότερα η εργασία στηρίχθηκε στο άρθρου 1.1.1 του παραρτήματος V, της οδηγίας 2000/60/Ε.Κ, στο οποίο προτείνονται συγκεκριμένοι υδρομορφολογικοί παράγοντες που υποστηρίζουν τα βιολογικά στοιχεία. Επιπλέον έγινε προσπάθεια αποτύπωσης των προβλημάτων που παρουσιάζονται κατά μήκος της κοίτης του Τριπόταμου από τις τροποποιήσεις που έχει υποστεί και προτάθηκαν μέτρα αποκατάστασης. Τέλος, από την σύγκριση των αποτελεσμάτων με αυτά που αναφέρονται στο Σχέδιο Διαχείρισης Λεκανών Απορροής  προκύπτει η αναγκαιότητα ύπαρξης περισσοτέρων του ενός σταθμού δειγματοληψιών

Flow, thermal and structural application of Ni-foam as volumetric solar receiver

Open-cell nickel foams with 92% porosity and uniform pore size and distribution were used in this study. The main objective of this work was to evaluate the behaviour of Ni-foam, when treated as volumetric receivers under concentrated solar radiation while improving their oxidation resistance, in order to make them attractive for such applications. The experimental investigation showed that their efficiency was depending on both materials parameters and flow conditions, the latter affecting the pressure drop and the heat transfer behaviour. The microstructural characterisation of oxide surface morphologies formed on the open-cell Ni foams exposed to concentrated solar radiation is investigated by the use of SEM and EDXS. SEM observations revealed a rapid homogeneous oxidation in the Ni-foam with three different surface oxide structures formed in relation with the process temperature. A novel slurry-based process for aluminising nickel foams while retaining their geometrical properties is applied in order to develop an aluminide-nickel intermetallic coating on a Ni foam thus enhancing the oxidation resistance. Scanning electron microscopy and X-ray diffraction were applied to assess the effectiveness of the aluminising process and determine the optimum parameters of the procedure (slurry composition, holding temperature and time).The authors would like to thank the PROcedes Materiaux et Energie Solaire (PROMES)–Centre National de la Recherche Scientifique (CNRS) for their support in the experimental procedure in the frame of the European Project SOLFACE.Publicad

A Two-dimensional Analytical Model for Prediction of the Radiation Heat Transfer in Open-cell Metal Foams

This is the accepted manuscript version of the following article: "Z. Jiang, et al., “A two-dimensional analytical model for prediction of the radiation heat transfer in open-cell metal foams”, Applied Thermal Engineering, Vol. 93: 1273-1281, October 2015." The final published version is available at: https://doi.org/10.1016/j.applthermaleng.2015.09.043 Copyright © 2015 Elsevier Ltd. All rights reserved. Article under Embargo until 23/10/17.In this article, a new two-dimensional (2D) explicit analytical model for the evaluation of the radiation heat transfer in highly porous open-cell metal foams is formulated and validated. A correction factor, C, is introduced to correct the deviation of the specific area in a simplified manner. Numerical results are compared with the published experimental data and three-dimensional (3D) model proposed in previous works. It reveals that the present two-dimensional model is proved to be relatively accurate in estimating the radiative conductivity for all the investigated structures. In the current work, the effects of the control parameters, such as the number of order in the iterative procedure, solid emissivity, the temperature difference, shape of solid particle and correction factor on the predictions of radiation characteristics are well discussed.Peer reviewe

Detection of Neolithic Settlements in Thessaly (Greece) Through Multispectral and Hyperspectral Satellite Imagery

Thessaly is a low relief region in Greece where hundreds of Neolithic settlements/tells called magoules were established from the Early Neolithic period until the Bronze Age (6,000 – 3,000 BC). Multi-sensor remote sensing was applied to the study area in order to evaluate its potential to detect Neolithic settlements. Hundreds of sites were geo-referenced through systematic GPS surveying throughout the region. Data from four primary sensors were used, namely Landsat ETM, ASTER, EO1 - HYPERION and IKONOS. A range of image processing techniques were originally applied to the hyperspectral imagery in order to detect the settlements and validate the results of GPS surveying. Although specific difficulties were encountered in the automatic classification of archaeological features composed by a similar parent material with the surrounding landscape, the results of the research suggested a different response of each sensor to the detection of the Neolithic settlements, according to their spectral and spatial resolution