ARCH effects and cointegration: Is the foreign exchange market efficient?

Extensive empirical work has produced mixed evidence regarding the validity of the unbiased efficient expectations hypothesis in the foreign exchange market. Empirical analysis in this paper, via cointegration techniques, produces the same inconclusive results for three currency markets, namely, the FFR/$US, the DM/$US and the Yen/$US foreign exchange market. However, when modeling conditional heteroskedasticity of exchange rates, through autoregressive conditional heteroskedasticity (ARCH) models, the results are fairly conclusive; the presence of the efficient foreign exchange market hypothesis is found in all these three currency markets.N/

The Feldstein-Horioka puzzle and exchange rate regimes: Evidence from cointegration tests

Many economists specialized in international finance claim that international capital markets are highly integrated (at least during the flexible exchange rate era). The main consequence of the above claim is that there is no longer any close relationship between investment and savings decisions. In other words, the close link between savings and investment ceases to exist under perfect capital mobility. Therefore, we construct a general equilibrium optimization model that is capable of generating artificial (model) data for savings and investment. Then, using the methodology of cointegration testing on these artificial data, we test whether there exists or not any link between savings and investment. The test is implemented between two different exchange rate regimes, that is, that of the Bretton Woods and that of the floating or flexible exchange rate regime. The results from the empirical analysis provide support for integrated capital markets over the second exchange rate era in the case of the United States of America.N/

Inflation volatility and stock prices: Evidence from ARCH effects

This paper examines the impact of inflation uncertainty on stock prices in developed as well as in emerging capital markets over the period 1980:1–93:12 via an Autoregressive Conditional Heteroskedasticity (ARCH) model for inflation. The results seem to support the presence of a negative association between inflation uncertainty and stock prices.N/

Stock returns and inflation volatility: Evidence from developed and emerging capital markets

N/

Integration of international capital markets: further evidence from EMS and non-EMS membership

The present paper examines whether real interest rates from nine financial markets—five European Monetary System (EMS) and four non-EMS markets—are financially integrated both on a world-wide basis and within each market individually. Monthly data on nominal interest rates and prices over the period 1982:1–1993:12 along with the methodology of cointegration are used to serve the purposes of the empirical analysis. The results provide support to the integrated market hypothesis as regards the financial markets considered altogether, as well as the financial markets in each `block' of markets. The presence of a systematic real interest rate relationship in the long run is accepted both on a non-EMS and an EMS basis. This relationship proves to be stronger on the EMS basis than on the non-EMS basis; this is probably due to the lower exchange rate volatility within the EMS environment.N/

Γεωμαγνητικές καταιγίδες και γεωμαγνητικές διαταραχές του 23ου και 24ου ηλιακού κύκλου

Ο Διαστημικός Καιρός είναι το σύνολο των διεργασιών και γεγονότων που λαμβάνουν χώρα στην περιοχή της γήινης μαγνητόσφαιρας και γύρω από αυτήν. Τα γεγονότα αυτά προκαλούνται κυρίως από διεργασίες που λαμβάνουν χώρα στον Ήλιο και διαδίδονται στον διαπλανητικό χώρο με την μορφή ενεργειακών δομών (π.χ. στεμματικές εκτοξεύσεις μάζας) φθάνοντας στη Γη επηρεάζοντας έτσι την μαγνητόσφαιρά της, με ποικίλα αποτελέσματα. Οι γεωμαγνητικές καταιγίδες είναι τα ισχυρότερα απ’αυτά και αποτελούν ισχυρές διαταραχές της γήινης μαγνητόσφαιρας, τόσο στη δομή της όσο και στην ένταση του μαγνητικού πεδίου της. Ένα αποτέλεσμα είναι η επιρροή των δορυφορικών συστημάτων μας από αυτές τις ισχυρές ηλιακές ενεργειακές δομές και τις γεωμαγνητικές καταιγίδες, με αποτέλεσμα την μη ορθή λειτουργία τους ή ακόμα και την καταστροφή τους, γεγονότα που μπορούν να κοστίσουν αρκετά τόσο σε οικονομικό όσο και σε λειτουργικό επίπεδο (π.χ. συστήματα πλοήγησης). Στην παρούσα εργασία παρουσιάζεται μια στατιστική μελέτη όλων των γεωμαγνητικών καταιγίδων των ηλιακών κύκλων 23 και 24 με την χρήση δεδομένων από τους επίγειους μετρητές για τους γεωμαγνητικούς δείκτες Kp και Dst. Σκοπός της εργασίας είναι να γίνει μια διερεύνηση στην κατανομή των γεωμαγνητικών καταιγίδων με την χρήση και των δύο γεωμαγνητικών δεικτών και να γίνει μια σύγκριση των αποτελεσμάτων. Καταγράφηκε ο αριθμός, η ένταση και η χρονική στιγμή των καταιγίδων και έγινε μια πρώτη σύγκριση μεταξύ των δύο ηλιακών κύκλων, καθώς και μελέτη της μηνιαίας και ετήσιας κατανομής τους στην διάρκεια των 22 μελετούμενων ετών και για τους δύο γεωμαγνητικούς δείκτες. Επιπλέον έχει γίνει μια Πιο συγκεκριμένα, με τον δείκτη Kp καταγράφηκαν 1030 γεωμαγνητικές καταιγίδες ενώ με τον δείκτη Dst καταγράφηκαν 523 καταιγίδες, περίπου το ήμιση των γεωμαγνητικών καταιγίδων απ’ότι καταγράφηκαν με τον δείκτη Kp. Αυτό δηλώνει ότι με τον δείκτη Kp καταγράφηκαν και οι μέτριες καταιγίδες (τύπου G1) οι οποίες ήταν σε αριθμό 675 και δεν είχαν τις απαραίτητες προδιαγραφές για να φτάσουν μέχρι το επίπεδο του Ισημερινού αλλά παρέμειναν μέχρι τα μεγάλα γεωγραφικά πλάτη. Μελετώντας τις καταιγίδες σε μηνιαία και ετήσια βάση στο τέλος παρουσιάζονται τα αποτελέσματα και τα συμπεράσματα αυτών των μελετών, καθώς και οι προοπτικές που προκύπτουν για περαιτέρω έρευνα και μελέτη. Τα κυριότερα απ’αυτά είναι : a) η μορφή της κατανομής των καταιγίδων είναι ξεκάθαρα συσχετισμένη με την μορφή του εντεκαετούς κύκλου, η οποία όμως φαίνεται ελαφρώς μετατοπισμένη στα μέγιστά της ως προς τα μέγιστα των ηλιακών κύκλων κατά 1-2 χρόνια. b) η εποχιακή εξάμηνη μεταβολή της γεωμαγνητικής δραστηριότητας, η οποία μας δείχνει ότι η γεωμαγνητική δραστηριότητα είναι μέγιστη κοντά στις Ισημερίες και ελάχιστη κοντά στα Ηλιοστάσια (Russell and McPherron, 1973). c) Η εμφάνιση χαμηλής γεωμαγνητικής δραστηριότητας στον ηλιακό κύκλο 24 η οποία και επιβεβαιώνει την χαμηλή δραστηριότητα αυτού του κύκλου (Jiang et al., 2015 ; Svalgaard Leif et al., 2005). Στο πρώτο κεφάλαιο δίδονται εισαγωγικές έννοιες για τον Ήλιο, την ηλιακή δραστηριότητα και τον διαπλανητικό χώρο. Στο δεύτερο κεφάλαιο δίνονται τα χαρακτηριστικά της δομής της γήινης μαγνητόσφαιρας και του πλάσματός της. Στο τρίτο κεφάλαιο δίνεται η σύζευξη των δύο συστημάτων Ηλίου-Γήινης μαγνητόσφαιρας και γίνεται αναφορά στον Διαστημικό Καιρό, τους γεωμαγνητικούς δείκτες που χρησιμοποιούνται για την περιγραφή του καθώς και τις μεθόδους πρόβλεψής του. Στο τέταρτο κεφάλαιο παρουσιάζεται η επεξεργασία των δεδομένων για τις γεωμαγνητικές καταιγίδες και η παρουσίαση των αποτελεσμάτων. Τέλος, στο πέμπτο κεφάλαιο δίνονται τα τελικά συμπεράσματα της επεξεργασίας, καθώς και οι προοπτικές που εμφανίζονται. Στο Παράρτημα της εργασίας αυτής αναφέρεται η βιβλιογραφία και οι σχετικές δημοσιεύσεις που χρησιμοποιήθηκαν καθ’όλη τη διάρκειά της, καθώς και οι πίνακες με όλες τις γεωμαγνητικές καταιγίδες που καταγράφηκαν με την βοήθεια των δύο γεωμαγνητικών δεικτών.Space Weather is the total of all processings and phenomena that occur in the area of Earth’s magnetosphere and around it. Most of these phenomena are born from processings that take place on the Sun and spread out to the interplanetary space, reaching the Earth and affect it’s magnetosphere with various effects on and in it. Geomagnetic storms are the most intense of these phenomena and are powerful disturbances of the Earth’s magnetosphere, both in its structure and in the intensity of its magnetic field. One effect is the influence on the satellite systems from these solar energetic structures and geomagnetic storms, with the result of malfunction or even destruction to the satellites’ systems, facts that can cause much both in economic and in operating terms (e.g. navigating systems). In this dissertation a statistical study of all geomagnetic storms of the solar cycles 23 and 24 was performed with the usage of data from ground monitors of the geomagnetic indices Kp and Dst. The aim of the dissertation is to investigate the distribution of geomagnetic storms with the use of both geomagnetic indices and to compare the results. The number, intensity and time of occurrence of the occurred storms were recorded and a comparison between the two cycles was done, as well as a study of their monthly and annual distribution for both geomagnetic indices. Specifically, 1030 geomagnetic storms were recorded with Kp index while with Dst index 523 storms were recorded. This implies that half of the geomagnetic storms that were recorded did not reach the Equator level but only reached the high latitudes. That is, with Kp index we also recorded the low intensity storms that did not have the necessary specifications to reach the Equator. At the end, the results and the conclusions are being presented, as well as the prospects arising for further research and study of all the above issues. The main ones are: a) The form of the storms distribution over the solar cycles, which seems to be slightly shifted to the solar cycles’ maximum by 1-2 years, but it is quite clear in its form and in its relation to the solar cycle. b) The clear semiannual variation of geomagnetic activity, which shows us that geomagnetic activity is maximal at Equinoxes and minimal at Solstices (Russell and McPherron, 1973). c) The occurrence of low geomagnetic activity at solar cycle 24 which confirms the low activity of this cycle (Jiang et al., 2015 ; Svalgaard Leif et al., 2005). In the first chapter introductory concepts for the Sun, solar activity and interplanetary space are being given. In the second chapter we give the characteristics of the structure and plasma of the Earth’s magnetosphere. The third chapter deals with the pairing of Solar-Earth’s magnetosphere systems and refers to Space Weather, the geomagnetic indices used to describe it and its forecasting methods. The forth chapter presents the processing of geomagnetic storms’ data and the presentation of the results. Finally, in the fifth chapter we give the final conclusions of the processing, as well as the future prospects that appear from the results. In the Appendix of this dissertation we refer the literature and related publications used throughout it, as well as the tables with all the geomagnetic storms recorded using the two geomagnetic indices

Leveraging Graph Analytics for Energy Efficiency Certificates

As energy efficiency is becoming a subject of utter importance in today’s societies, the European Union and a vast number of organizations have put a lot of focus on it. As a result, huge amounts of data are generated at an unprecedented rate. After thorough analysis and exploration, these data could provide a variety of solutions and optimizations regarding the energy efficiency subject. However, all the potential solutions that could derive from the aforementioned procedures still remain untapped due to the fact that these data are yet fragmented and highly sophisticated. In this paper, we propose an architecture for a Reasoning Engine, a mechanism that provides intelligent querying, insights and search capabilities, by leveraging technologies that will be described below. The proposed architecture has been developed in the context of the H2020 project called MATRYCS. In this paper, the reasons that resulted from the need of efficient ways of querying and analyzing the large amounts of data are firstly explained. Subsequently, several use cases, where related technologies were used to address real-world challenges, are presented. The main focus, however, is put in the detailed presentation of our Reasoning Engine’s implementation steps. Lastly, the outcome of our work is demonstrated, showcasing the derived results and the optimizations that have been implemented

An Advanced Visualisation Engine with Role-Based Access Control for Building Energy Visual Analytics

<p>One of the main challenges of today’s societies is the avoidance of the climate change since the climate crisis in now more evident than ever. Buildings have a large share of total energy consumption and, thus, it is obvious that actions should be taken to reduce their needs. Taking into consideration that nowadays data related to building’s metrics are available in significantly higher rate than in the past, due to the advance of the related technologies, it is necessary to find ways to exploit them in order to draw useful inferences regarding their consumptions and how they can be reduced. For that reason, in this paper we present a Visualisation Engine, which offers a variety of visualisations over stored data. With the usage of the proposed Visualisation Engine, we envision to be able to conduct sufficient research over the data, to generate insightful information regarding their behaviour, and to assist the development of useful solutions towards the direction of more energy efficient buildings.</p&gt

A Reasoning Engine Architecture for Building Energy Metadata Management

<p>During the Buildings’ lifecycle, massive amounts of data, that contain information related to their energy consumption, are generated. Towards the creation of smart building networks, this produced information must be intercepted and harmonized according to building ontologies and schemas. The pattern recognition from building metadata is based on inferencing and intelligent querying, that can be achieved with the utilization of graph and property databases that deploy and host building information. This paper presents a Reasoning Engine Architecture implemented in the context of the H2020 project called MATRYCS that persists building semantic information. It will be leveraged to support real life applications by improving the inference operations.</p&gt

Machine Learning Approach for Rapid Estimation of Five-Day Biochemical Oxygen Demand in Wastewater

Improperly managed wastewater effluent poses environmental and public health risks. BOD evaluation is complicated by wastewater treatment. Using key parameters to estimate BOD in wastewater can improve wastewater management and environmental monitoring. This study proposes a BOD determination method based on the Artificial Neural Networks (ANN) model to combine Chemical Oxygen Demand (COD), Suspended Solids (SS), Total Nitrogen (T-N), Ammonia Nitrogen (NH4-N), and Total Phosphorous (T-P) concentrations in wastewater. Twelve different transfer functions are investigated, including the common Hyperbolic Tangent Sigmoid (HTS), Log-sigmoid (LS), and Linear (Li) functions. This research evaluated 576,000 ANN models while considering the variable random number generator due to the ten alternative ANN configuration parameters. This study proposes a new approach to assessing water resources and wastewater facility performance. It also demonstrates ANN’s environmental and educational applications. Based on their RMSE index over the testing datasets and their configuration parameters, twenty ANN architectures are ranked. A BOD prediction equation written in Excel makes testing and applying in real-world applications easier. The developed and proposed ANN-LM 5-8-1 model depicting almost ideal performance metrics proved to be a reliable and helpful tool for scientists, researchers, engineers, and practitioners in water system monitoring and the design phase of wastewater treatment plants