Main drivers of the ECB financial accounts and ECB financial strength over the first 11 years

This paper analyses the main drivers of the ECB’s balance sheet and profit and loss account over the first 11 years of the ECB’s existence. Furthermore, the paper assesses the financial strength of the ECB. As monetary policy operations are normally conducted by national central banks under the impulse and instructions from the ECB, the Eurosystem balance sheet is the primary reference for the analysis of Eurosystem monetary policy operations. Three main drivers of the balance sheet and profit and loss account are identified. Firstly, financial market developments and portfolio management decisions imply changes in the value of the foreign reserve and own funds portfolios, which represent a substantial part of the balance sheet (with the share of own funds becoming increasingly larger over the period under review). At the same time, the profit and loss account depends to an important degree on interest income and expenses, realised gains and losses, and write-downs on these portfolios. Secondly, strong banknote demand has gradually increased the size of the balance sheet since the euro changeover in 2002. Banknotes in circulation also provide a strong base for seigniorage income, which is an important item of the profit and loss account. Thirdly, the liquidity-providing operations in foreign currency, which the Eurosystem has undertaken since 2007 in response to the fi nancial crisis, increased significantly the size of the ECB’s (and the Eurosystem’s) balance sheet. In terms of income and expenses, these operations were rather immaterial at the level of the ECB, although the income generated was substantial at the Eurosystem level. The ECB has remained financially strong over the 11-year period. Factors that support the financial position are strong legislative provisions on e.g. independence and income, the use of financial buffers, seigniorage as a reliable income source and an effective loss-coverage mechanism. JEL Classification: D21, D92, E22, E52central bank balance sheet, central banking, financial accounts, financial strength

Βελτιστοποίηση σχεδιασμού και ανάλυση μη συμβατικών συνδέσεων στεγάστρου σιδηροδρομικού σταθμού

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Δομοστατικός Σχεδιασμός και Ανάλυση των Κατασκευών

The sex ratio of fetal deaths and its potential relation with the decline of sex ratio at birth in Greece

Many factors that affect teratogenesis and fetal death may vary from one region to another as well as in dif­ferent time periods. Our aim was to identify trends in the sex ratio of intrauterine fetal deaths, and its relationship with the secondary sex ratio (SSR) observed in our country. We reviewed the files of 276 consecutive autopsies performed during the last 16 years. 189 cases were spontaneous abortions and fetal deaths (SAs/FDs); 128 cases in total presented congenital malformations, out of which 87 were pregnancies terminated deliberately due to birth defects detected during the prenatal screening. In the total number of cases studied, 60.6% were male and 39.4% female. In the SAs/FDs group 62.71% were male, and 37.29% female or male to female ratio: 1.68. In the congenital malformations group 59.3% were male and 40.7% females. In addition 71.1% of the cases with intrauterine growth retardation were male and 28.9% female. SSR in Greece shows a trend to decline from 1960 to 2007. This downward tendency in SSR is greater between 1980-2007, (R2 = 0.229, ANOVA p = 0.028) and even more significant between 1980-1990 (R2 = 0.452, ANOVA p = 0.023). In conclusion, we have found a significant male preponderance in both the spontaneously aborted fetuses, and the fetuses with congenital malformations and/or intrauterine growth retardation. We suggest that this finding may be related to the decline in SSR observed during the last decades in Greece. Similar trends have been recently recorded in U.S.A., Japan and other westernalised countries, and have been attributed to greater prenatal vulnerability of the male fetus, especially at the earlier stages of gestation

Knowledge-Based Reward Shaping with Knowledge Revision in Reinforcement Learning

Reinforcement learning has proven to be a successful artificial intelligence technique when an agent needs to act and improve in a given environment. The agent receives feedback about its behaviour in terms of rewards through constant interaction with the environment and in time manages to identify which actions are more beneficial for each situation. Typically reinforcement learning assumes the agent has no prior knowledge about the environment it is acting on. Nevertheless, in many cases (potentially abstract and heuristic) domain knowledge of the reinforcement learning tasks is available by domain experts, and can be used toimprove the learning performance. One way of imparting knowledge to an agent is through reward shaping which guides an agent by providing additional rewards. One common assumption when imparting knowledge to an agent, is that the domain knowledge is always correct. Given that the provided knowledge is of a heuristic nature, there are cases when this assumption is not met and it has been shown that in cases where the provided knowledge is wrong, the agent takes longer to learn the optimal policy. As reinforcement learning methods are shifting more towards informed agents, the assumption that expert domain knowledge is always correct needs to be relaxed in order to scale these methods to more complex, real-life scenarios. To accomplish that, the agents need to have a mechanism to deal with those cases where the provided expert knowledge is not perfect. This thesis investigates and documents the adverse effects erroneous knowledge can have to the learning process of an agent if care is not taken. Moreover, it provides a novel approach to deal with erroneous knowledge through the use of knowledge revision principles, in order to allow agents to use their experiences to revise knowledge and thus benefit from more accurate shaping. Empirical evaluation shows that agents that are able to revise erroneous parts of the provided knowledge, can reach better policies faster when compared to agents that do not have knowledge revision capabilities

Multiscale experimentation & modeling of fatigue crack development in aluminium alloy 2024.

The objective of this research project is to be able to understand the role of various microstructural features on Fatigue Crack Initiation (FCI) of metallic alloys. By employing a novel experimental set-up, mechanical testing was performed in situ within an SEM chamber, and the deformation of the individual grains was observed real time. A physically-based Crystal Plasticity (CP) model was then developed that accurately predicts the macro and micro mechanical behaviour for Al2024 T3. An experimentally informed FCI criterion was developed that accounts for the effect of local slip bands and the applied local strains. While ‘precious’ insights were given on the small crack growth regime observing the occurring microscale phenomena. FCI is a multiscale process and thus evaluating the microscale does not cover fully the understanding of local deformation and damage. Thus a multiscale DIC process was employed to better understand the macro and mesoscale as well. 3D Digital Image Correlation (DIC) was employed and the strain distributions (at the sample scale) were obtained for various loading conditions. High magnification camera based 2D DIC was then used and the strain measurements were also extracted at clusters of grains. Useful observations were given for the different strain components (εxx, εyy, εxy). Finally the total fatigue lifetime of the component was compared to the modeled FCI for various loading conditions

Do additive manufactured parts deserve better?

Additive manufacturing of metallic components is regarded as one of the more exciting developments in engineering. The combined attractions of near net shape, tailored composition, and geometry optimisation have led to much interest in the various processes used and a drive to improve the mechanical properties to match those of wrought parts. In this paper, we reflect on the apparent lack of ambition in optimising the structural integrity of parts made using these new manufacturing processes. The current research focus seems to be either on largely irrelevant static properties, or on quantifying the fatigue response in a way that would be familiar to engineers in the 19th Century. Given the work on the role of microstructure and fatigue, which dates back to Ewing and Humphrey in 1903 reaching its zenith in the 1980s and 90s with Keith Miller in the vanguard, and recent developments in both imaging technologies and sophisticated numerical modelling, all the elements are in place for a much more rigorous, and ultimately more fruitful, approach to understand the structural integrity of additive manufactured components

Recent coastline changes of fan-deltas in the Western Gulf of Corinth, Central Greece

Στην παρούσα εργασία επιχειρείται η εκτίμηση των πρόσφατων μεταβολών της ακτογραμμής των δελταϊκών ριπιδίων των ποταμών Φοίνικα, Θολοπόταμο, Λαγκάδι, Μεγανίτα, Σελινούντα, Κερυνίτη και Βουραϊκού, με τη χρήση μεθόδων τηλεπισκόπησης και ΣΓΠ. Τα δελταϊκά αυτά ριπίδια ηλικίας Ανώτερου Ολόκαινου έχουν σχηματισθεί από ποτάμια μεγάλης μορφολογικής κλίσης που αποθέτουν το αδρομερές φορτίο ιζημάτων τους κατά μήκος των νότιων ακτών του δυτικού Κορινθιακού κόλπου (Β. Πελοπόννησος). Για τους σκοπούς της εργασίας δημιουργήθηκε και οργανώθηκε μια ψηφιακή βάση δεδομένων για την περιοχή αποτελούμενη από λεπτομερή (κλίμακας 1:5.000) τοπογραφικά διαγράμματα και γεωμετρικά διορθωμένες και γεωαναφερμένες αεροφωτογραφίες λήψης 1945, 1996 και 2008. Η σύγκριση των ακτογραμμών των δελταϊκών ριπιδίων κατά τα έτη 1945, 1996 και 2008 οδήγησε στον προσδιορισμό των τμημάτων της ακτογραμμής πουυπόκεινται σε διάβρωση καθώς και εκείνων που προελαύνουν. Η κύρια διεργασία κατά μήκος του μεγαλύτερου μήκους της ακτογραμμής είναι η διάβρωση. Ομεγαλύτερος ρυθμός διάβρωσης ήταν 2,44 m/έτος (μεταξύ των ετών 1945 και 1996) και σημειώθηκε περίπου 150 m δυτικά των εκβολών του ποταμού Φοίνικα. Αντίθετα οι υψηλότεροι ρυθμοί προέλασης μετά το 1945 ήταν 3,10 και 3,00 m/έτος και σημειώθηκαν στις περιοχές των ενεργών εκβολών των ποταμών Βουραϊκού και Σελινούντα αντίστοιχα.This study deals with the assessment of recent shoreline change rates along the fandeltas of Finix, Tholopotamo, Lagadi, Meganitas, Selinous, Kerinitis, and Vouraikos streams by using GIS and Remote Sensing techniques. These Late Holocene fandeltas have been formed by high gradient braided streams that deposit their coarse sediment load along the southern coast (North Peloponnese) of the western Gulf of Corinth. For the purposes of the study a spatial database was constructed, organized and implemented consisting of analogue detailed (at the scale of 1:5000) topographic diagrams, and orthorectified aerial photos taken in 1945, 1996 and 2008. Comparisons of fan-deltas shoreline positions for the periods 1945 vs. 1996 and 1945 vs. 2008 were made and the segments of the coastline along the aprons of the fan-deltas which are subject to erosion accretion were defined. Coastal erosion is the main dominant geomorphic process along a significant part of the fan deltas coastline. The highest retreat rate value (2.44 m/yr for the period 1945-1996) was estimated for the Finix stream fan delta, about 150 m west of the river mouth, while the highest accretion rates since 1945 (3.10 and 3.00 m/yr) occurred at the mouths of Vouraikos and Selinous rivers respectively

ZERO-SHOT DOMAIN ADAPTATION FOR SKETCH RECOGNITION

Στην παρούσα εργασία αντιμετωπίζουμε το πρόβλημα του “zero-shot domain adaptation” μεταξύ των πεδίων των εικόνων και σκίτσων. Τον όρο "zero-shot" τον εννοούμε ως προς τα σκίτσα. Ο όρος "domain adaptation" υπονοεί ότι πρόκειται να μάθουμε χρησιμοποιώντας εικόνες ως παραδείγματα και θα χρησιμοποιήσουμε αυτή τη γνώση για να προβλέψουμε σκίτσα. Για να το κάνουμε αυτό, θα κάνουμε έναν μετασχηματισμό στις παρατηρούμενες εικόνας και έναν μετασχηματισμό στα παρατηρούμενα σκίτσα έτσι ώστε τα μετασχηματισμένα δεδομένα να μπορεί να θεωρηθεί ότι παράχθηκαν από την ίδια τυχαία μεταβλητή. Μετά από αυτό, η στρατηγική μας είναι να προσαρμόσουμε μια συνάρτηση στις εικονες που έχουν μετασχηματιστεί και να προβλέψουμε με αυτή τα σκίτσα κανονικά. Οι μετασχηματισμοί που πρόκειται να χρησιμοποιήσουμε έχουν ως βασικότερο στόχο να αναπαραστήσουν και τους δύο τομείς ως δυαδικές ακμές πάχους ενός εικονοστοιχείου, κωδικοποιώντας με 1 την ύπαρξη ακμής και με 0 την απουσία της. Για τον τομέα της εικόνας θα χρησιμοποιηθεί ένας συνδυασμός διαδικασιών ανίχνευσης ακμών, αυτόματης κατωφλίωσης και λέπτυνσης σε μια φιλοσοφία επαύξησης δεδομένων. Για τον τομέα του σκίτσου θα χρησιμοποιήσουμε έναν ντετερμινιστικό κανόνα κατωφλίωσης σε συνδυασμό με μια διαδικασία λέπτυνσης.In this thesis we are tackling the zero-shot domain adaptation problem between the image and the sketch domains. By "zero-shot" we mean in term of sketches. The term "domain adaptation" suggests that we are going to learn with images as examples and we will use that knowledge to predict sketches. In order to do this we are going to make one transformation to the image realizations and one transformation to the sketch realizations such that the transformed realizations can be seen as they were sampled from the same random variable. After that our strategy is to learn a function on the transformed realizations of the image domain and predict our sketches normally. The transformations we are going to use have as an objective to represent both domains as one-pixel thick binary edge maps, encoding with 1 the existence of an edge and with 0 the absence of it. For the image domain a combination of edge detection, thresholding and thinning procedures is going to be used in a data augmentation philosophy. For the sketch domain we will use a deterministic thresholding rule followed by a thinning procedure