Η πολύπλοκη μορφή που απέκτησαν οι χρηματοοικονομικές αγορές κατά τη διάρκεια των δύο τελευταίων δεκαετιών, είχε ως αποτέλεσμα την απώλεια πολύ υψηλών κεφαλαίων από τις επιχειρήσεις και από τις τράπεζες. Η ανάγκη για συστηματική μέτρηση του χρηματοοικονομικού κινδύνου οδήγησε στην επινόηση του μεγέθους της αξίας σε κίνδυνο (Value-at-Risk, VaR). Η μέθοδος αυτή παρέχει στον ενδιαφερόμενο έναν αριθμό που εκφράζει τη μέγιστη αναμενόμενη ζημία μίας επένδυσης για δεδομένη χρονική περίοδο και δεδομένο επίπεδο εμπιστοσύνης. Παρά το γεγονός ότι η VaR έχει κάποιους περιορισμούς που απαιτούν τη χρήση stress test και scenario test, συνολικά, η VaR είναι η καλύτερη ανεξάρτητη τεχνική μέτρησης των κινδύνων που είναι διαθέσιμη. Στόχος της παρούσας διπλωματικής εργασίας είναι η μέτρηση της VaR ενός χαρτοφυλακίου. Επιπλέον, μέσα από αυτήν την εργασία θα γίνει κατανοητό τι είναι η VaR, πώς μπορεί να υπολογιστεί, ποια είναι τα κύρια χαρακτηριστικά της και ποια είναι τα πλεονεκτήματα και τα μειονεκτήματά της. Τέλος, ιδιαίτερη έμφαση δίνεται στην παρουσίαση των μεθόδων υπολογισμού της VaR. / The inextricable form of the financial markets during the last two decades result in the loss of high capital from the businesses and banks. The need of a systemic measurement of the financial risk leads to the invention of the Value-at-Risk method. This method provides the interested person with a number which expresses the potential maximum loss of an investment for a given period of time and a given confidence level. Despite the fact that VaR has some restrictions demanding the use of stress test and scenario test, altogether, VaR is the best independent measuring technique of the risks that it is available. The aim of this dissertation is to measure the VaR of a portfolio. Moreover, it will be registered what VaR is, how it can be measured, which are its main characteristics, its advantages and disadvantages. Lastly, more emphasis is given to the presentation of the measuring methods of VaR.

L'utilisation des goujons collés dans les structures bois répond au souci de conservation du bâti et de discrétion de l'intervention. A ce jour, plusieurs procédés de caractérisation et de dimensionnement sont disponibles, sans pour autant donner un socle commun à l'évaluation de la résistance des assemblages collés. L'utilisation des goujons collés suscite des interrogations concernant leur tenue au feu. Bien que le matériau bois entourant les tiges de renforcement soit isolant, il est nécessaire de fournir de plus amples estimations concernant la tenue mécanique des polymères pour différentes températures que l'on pourrait trouver au sein d'une liaison au cours d'un incendie. La présente étude permet de coupler méthodes expérimentales et simulations numériques, afin d'appréhender les mécanismes gouvernant la rupture de ces assemblages. La caractérisation expérimentale permet d'estimer les propriétés mécaniques locales des assemblages suivant divers paramètres (les longueurs de scellement, l'orientation du fil du bois, l'essence de bois, ou encore la température d'exposition), ainsi que les propriétés intrinsèques aux matériaux constitutifs. Cette base de données expérimentale est indispensable pour l'ajustement du modèle aux éléments finis en élasticité linéaire. L'approche numérique met en évidence une présence importante de contraintes normales en tête de collage, avant l'apparition de contraintes de cisaillement. Les outils de la Mécanique Linéaire Élastique de la Rupture équivalente permettent d'établir des courbes de résistance liées à chaque mode de ruine (mode I et mode II). Enfin, afin de décrire précisément le processus complet de rupture de ces assemblages, un critère de rupture en mode mixte (mode I et mode II) est utilisé. Une formulation analytique permettant d'estimer la charge au pic est proposée et permettra la réalisation d'abaques de dimensionnement des assemblages par goujons collés, utilisables en bureau d'études.

An experimental evaluation of the mixed-mode fracture behavior of bonded composite joints is presented. Commonly used experimental techniques for characterizing the mode I, mixed-mode I/II, mode II, and mode III fracture behavior have been employed for the purpose of developing a fracture envelope to be utilized in the automotive design process. These techniques make use of such test geometries as the double cantilever beam (DCB), asymmetric double cantilever beam (ADCB), single-leg bend (SLB), end-loaded split (ELS), and split cantilever beam (SCB) specimens. Symmetric versions of the DCB, SLB, and ELS specimens produced mode mixities of 0°, 41°, and 90° respectively, while the testing of ADCB specimens allowed for mode mixities of 18°, 31°. Pronounced stick-slip behavior was observed for all specimen test geometries under both quasi-static and dynamic loading conditions. Due to the nature of the adhesive studied, a limited number of data points were obtained under mode I loading conditions. A significant increase in the number of measurable crack initiation events was observed for mixed-mode I/II loading conditions, where stick slip behavior was less pronounced. Additionally, a comparison of the measured fracture energies obtained under mixed-mode I/II loading conditions reveals that the addition of a small mode II component results in a decrease in the mode I fracture energy by roughly 50%, as the crack was driven to the interface between the adhesive layer and composite adherends. Furthermore, the propensity of debonds to propagate into the woven composite laminate adherends under mode II loading conditions limited the number of crack initiation points that could be obtained to one or two usable data points per specimen. A limited number of experimental tests using the SCB specimen for mode III fracture characterization, combined with a numerical analysis via finite element analysis, revealed a significant mode II contribution toward the specimen edges. Similarly, FE analyses on full bond width and half bond width SCB specimens was conducted, and results indicate that by inducing a bond width reduction of 50%, the mode II contribution is greatly decreased across the entire width of the specified crack front. To provide a means for comparison to results obtained using the standard DCB specimen, an alternative driven wedge test specimen geometry was analyzed, as this geometry provided a significant increase in the number of measurable data points under mode I loading conditions. A three-dimensional finite element analysis was conducted to establish ratios of simple beam theory results to those obtained via FEA, GSBT/GFEA, were of particular interest, as these ratios were used to establish correction factors corresponding to specific crack lengths to be used in correcting results obtained from an experimental study utilizing a driven wedge technique. Corrected results show good agreement with results obtained from traditional mode I double cantilever beam tests. Finally, bulk adhesive experiments were conducted on compact tension specimens to establish a correlation between adhesively bonded composite joint and bulk adhesive fracture behavior under mode I loading conditions. Measured fracture energy values were shown to gradually drop across a range of applied loading rates, similar to the rate-dependent behavior observed with both the DCB and driven wedge specimens. Application of the time-temperature superposition principle was explored to determine whether or not such techniques were suitable for predicting the fracture behavior of the adhesive studied herein. Good correlation was established between the fracture energy values measured and the value of tan d obtained from dynamic mechanical analysis tests conducted at corresponding reduced test rates. / Master of Science

This study attempts to offer an ecological interpretation of Genesis 1: 1-2:4a in view of the question as to what extent this passage bears footprints of anthropocentrism, on the one hand, and/or ecological wisdom, on the other hand. Extant ecological readings of this text tend to either recover its ecofriendliness, or they criticise the text on the basis of its dominion and subdual language in Genesis 1:26-28 which seems to go against the grain of ecological sensibilities. In resonance with revisionist readings, this study shows that the only way to mollify the dominion language of Genesis I :26-28 is to read this section as part of the whole Priestly creation account. Elements of the exilic context and many literary features of Genesis I: l-2:4a present humans as a member of a world of interdependences. Hence, accusing Genesis I: l-2:4a of lying at the root of modern indifference towards nature, is not the whole story. / Old Testament & Ancient Near Eastern Studies / M. A. (Biblical Studies)

This study attempts to offer an ecological interpretation of Genesis 1: 1-2:4a in view of the question as to what extent this passage bears footprints of anthropocentrism, on the one hand, and/or ecological wisdom, on the other hand. Extant ecological readings of this text tend to either recover its ecofriendliness, or they criticise the text on the basis of its dominion and subdual language in Genesis 1:26-28 which seems to go against the grain of ecological sensibilities. In resonance with revisionist readings, this study shows that the only way to mollify the dominion language of Genesis I :26-28 is to read this section as part of the whole Priestly creation account. Elements of the exilic context and many literary features of Genesis I: l-2:4a present humans as a member of a world of interdependences. Hence, accusing Genesis I: l-2:4a of lying at the root of modern indifference towards nature, is not the whole story. / Biblical and Ancient Studies / M. A. (Biblical Studies)