In this thesis, we study various aspects of physics in higher-dimensional manifolds involving a single extra dimension. After giving some historical perspective on the motivation for studying higher-dimensional theories of physics, we describe classical tests for a non-compact extra dimension utilizing test particles and pointlike gyroscopes. We then turn our attention to the problem of embedding any given <i>n</i>-dimensional spacetime within an (<i>n</i>+1)-dimensional manifold, paying special attention to how any structure from the extra dimension modifies the standard <i>n</i>-dimensional Einstein equations. Using results derived from this investigation and the formalism derived for test particles and gyroscopes, we systematically introduce three specific higher-dimensional models and classify their properties; including the Space-Time-Matter and two types of braneworld models. The remainder of the thesis concentrates on specific higher-dimensional cosmological models drawn from the above mentioned scenarios; including an analysis of the embedding of Friedmann-Lemaitre-Robertson-Walker submanifolds in 5-dimensional Minkowski and topological Schwarzschild spaces, and an investigation of the dynamics of a <i>d</i>-brane that takes the form of a thin shell encircling a (<i>d</i>+2)-dimensional topological black hole in anti-deSitter space. The latter is derived from a finite-dimensional action principle, which allows us to consider the canonical quantization of the model and the solutions of the resulting Wheeler-DeWitt equation.

Oil and natural gas are the most strategic raw materials to meet the expanding energy requirement in today&rsquo / s world. They have great impact on issues such as economy, national security, development, competition, and political consistency. Being a developing country, Turkey&rsquo / s natural gas requirement is increasing rapidly. However, the production is far from covering the demand. Recent assumptions point out that natural gas demand of Turkey will reach 44 billion cubic meters in 2010 with a financial burden of 10 billion $ to the national economy. Therefore Turkey requires meeting natural gas demand by using its own conventional natural gas resources. The geological researches and global data encourage Turkey to drill more exploration wells in offshore side of Western Black Sea .In early 2007, the production will be started in Western Black Sea Region with 1.42 million cubic meter gas per day. Moreover, further exploration and production activities in the region are still continuing in order to increase the production. In this thesis, issues such as importance of the natural gas for Turkey and the world, Turkey&rsquo / s present energy situation and natural gas supply and demand scenarios for Turkey have been investigated. The possible impact of natural gas exploration and production in Black Sea region on Turkey&rsquo / s economy in near future has been emphasized. An extensive literature survey using related printed and unprinted media has been performed in order to collect the necessary data and information.

Benchmark calculations for the validation of the coupled neutron kinetics/thermohydraulic code complex DYN3D-ATHLET are described. Two benchmark problems concerning hypothetical accident scenarios with leaks in the steam system for a VVER-440 type reactor and the TMI-1 PWR have been solved. The first benchmark task has been defined by FZR in the frame of the international association "Atomic Energy Research" (AER), the second exercise has been organised under the auspices of the OECD. While in the first benchmark the break of the main steam collector in the sub-critical hot zero power state of the reactor was considered, the break of one of the two main steam lines at full reactor power was assumed in the OECD benchmark. Therefore, in this exercise the mixing of the coolant from the intact and the defect loops had to be considered, while in the AER benchmark the steam collector break causes a homogeneous overcooling of the primary circuit. In the AER benchmark, each participant had to use its own macroscopic cross section libraries. In the OECD benchmark, the cross sections were given in the benchmark definition. The main task of both benchmark problems was to analyse the re-criticality of the scrammed reactor due to the overcooling. For both benchmark problems, a good agreement of the DYN3D-ATHLET solution with the results of other codes was achieved. Differences in the time of re-criticality and the height of the power peak between various solutions of the AER benchmark can be explained by the use of different cross section data. Significant differences in the thermohydraulic parameters (coolant temperature, pressure) occurred only at the late stage of the transient during the emergency injection of highly borated water. In the OECD benchmark, a broader scattering of the thermohydraulic results can be observed, while a good agreement between the various 3D reactor core calculations with given thermohydraulic boundary conditions was achieved. Reasons for the differences in the thermohydraulics were assumed in the difficult modelling of the vertical once-through steam generator with steam superheating. Sensitivity analyses which considered the influence of the nodalisation and the impact of the coolant mixing model were performed for the DYN3D-ATHLET solution of the OECD benchmark. The solution of the benchmarks essentially contributed to the qualification of the code complex DYN3D-ATHLET as an advanced tool for the accident analysis for both VVER type reactors and Western PWRs.

Many scenarios try to describe a future of supply and demand for electricity in Sweden. All the studied scenarios contain an increased amount of variable renewable energy (VRE) power production. VRE power sources, such as solar and wind power, depend on weather conditions, like solar irradiance and wind speed. There are also scenarios predicting an increased amount of plug-in electrical vehicles (PEVs), which charge their batteries from the electricity grid and thereby changes the consumption patterns. In a future power system with less nuclear power and increased VRE power production it is of interest to investigate the scenarios impact on supply and demand. The scenarios were compiled into cases for the years 2030, 2050, and 2100. Simulations of each case VRE shares resulted in hourly power production data. Aggregating the data and comparing it with the consumption gives an understanding of the power and regulation need.  For Case 2030, a VRE share of 10.3% was calculated. The hydropower in Sweden could cover the power need for the whole year and even peaks in demand. For the larger shares of Case 2050 and 2100, hydropower was not able to cover peaks in power demand solemnly. The consumption of PEVs was small for all cases, reaching shares of 1.5% to 7.1%, compared to the consumption of all other sectors. Considering short-term statistics for wind power and the latest news that some of Sweden’s nuclear reactors might shut down in advance, it is possible that Case 2030 might occur sooner than predicted. If larger shares of VRE power have to be produced to meet consumer needs in the near future, grid-stabilizing measures has to be investigated.

Water resources availability could be affected by alterations of hydrologic processes as a result of climate change. Global projections of climate change indicate negative impacts on water systems with increasing flooding and drought events. This investigation presents the modeling of climate change effects on the hydrology and water resources availability in the Rio Conchos basin, the main tributary of the lower portion of the bi-national Rio Grande/Bravo basin, and its impact on the water treaty signed between the United States of America and Mexico in 1944. One of the problems most relevant to the study basin is the frequent occurrence of long drought periods. Coupled with increased water demands and low irrigation efficiencies, the competition for water resources is high on both sides of the border. Three main parts are addressed in this research. First, a hydrologic model has been developed using the one-dimensional, 2 layer soil moisture accounting scheme embedded in a water evaluation and planning model. Second, downscaled precipitation and temperature data, from five general circulation models for two emission scenarios, A1B and A2, were used as inputs to the Rio Conchos hydrologic model to determine the effect on basin hydrology. A multi-model ensemble is developed and several techniques, such as probability density functions, wavelet analysis, and trend analysis, are used to assess the impacts. Third, a water resources planning model for the basin has been developed, which integrates the hydrologic model and water management modeling, to evaluate the impacts on the entire water system and simulate adaptive strategies to mitigate climate change in the study basin. Skill-weighted multi-model ensemble results show that annual average runoff may be reduced by 12% ± 53% and 20% ± 45% in 2080-2099 relative to 1980-1999 for the A1B and A2 scenarios, respectively. Likewise, results show that reliability and resiliency of the water system will tend to decrease; consequently, the vulnerability of the system increases over time. Proposed adaptation measures could make the system more reliable and less vulnerable in meeting water demands for irrigation and municipal uses. / text

Στην παρούσα μεταπτυχιακή διπλωματική εργασία μελετήθηκε το πρόβλημα Δρομολόγησης Στόλου Οχημάτων με Παράθυρα Χρόνου (VRPTW) κάτω από ένα φιλικό προς το περιβάλλον πρίσμα που απαιτεί την δημιουργία ισορροπημένων και συμπαγών συστάδων. Παρουσιάζεται μια νέα ευρετική προσέγγιση που αποτελείται από τρεις φάσεις: (i) συσταδοποίηση των πελατών με συμβατά παράθυρα χρόνου, (ii) συσταδοποίηση των πελατών που βρίσκονται γεωγραφικά κοντά χρησιμοποιώντας διάφορες μεθόδους (φυσικές αποκοπές, KaHIP, τετραδικά δένδρα), (iii) μια φάση εκλέπτυνσης που είτε χωρίζει μια συστάδα σε μικρότερες, είτε συγχωνεύει συστάδες δημιουργώντας μια συμπαγή μεγαλύτερη συστάδα. Η νέα προσέγγιση αποδίδει πολύ καλά όταν χρησιμοποιείται σε δυναμικά σενάρια στα οποία ζητούνται αλλαγές στην αρχικά υπολογισμένη διαδρομή (προσθήκη μιας νέας παραγγελίας ή ακύρωση κάποιας παραγγελίας). Η νέα μέθοδος αποτελεί ένα πολύ καλό σημείο εκκίνησης για επανεξέταση και περαιτέρω βελτιστοποίηση της λύσης του προβλήματος Δρομολόγησης Στόλου Οχημάτων με Παράθυρα Χρόνου. Πειράματα που έγιναν με πραγματικά σύνολα δεδομένων δείχνουν ότι η νέα προσέγγιση υπερέχει σε σχέση με τις συνήθεις προσεγγίσεις που ξεκινούν από μία βασική λύση. / We investigate the Vehicle Routing Problem with Time Windows (VRPTW) under a new approach, consisting of three major phases: (i) a first clustering of customers with compatible time windows; (ii) a second clustering of customers with close geographic proximity based on various methods (natural cuts, KaHIP, quad trees); (iii) a refinement phase that either splits a cluster into smaller ones, or merges clusters to form a bigger compact cluster. Our approach turns out to be beneficial when used in an on-line environment, where changes to the initial tour are requested (add a new customer to the tour or drop some customers). The new method serves as a warm starting point for re-evaluating and further optimizing the solution of VRPTW. Experiments with real data sets demonstrate that our approach compares favorably with standard approaches that start from a basic (cold) solution.

Αντικείμενο της παρούσας διπλωματικής εργασίας αποτελεί ο σχεδιασμός του γλωσσικού μαθήματος στο Δημοτικό Σχολείο και ειδικότερα, ο τρόπος διδασκαλίας της γραμματικής της ελληνικής γλώσσας στους μαθητές. Πιο συγκεκριμένα, διερευνάται ο ορισμός της έννοιας γραμματική και δίνεται ιδιαίτερη έμφαση στον τρόπο διδασκαλίας της λειτουργικής γραμματικής και φυσικά η αποτελεσματικότητα της στην επίδοση των μαθητών. Επιπλέον, η διδασκαλία της λειτουργικής γραμματικής συνδέεται με την ανάπτυξη διδακτικών σεναρίων αναφορικά με το γλωσσικό μάθημα. Επιχειρείται, λοιπόν, ο σχεδιασμός κάποιων ενδεικτικών διδακτικών σεναρίων για το γλωσσικό μάθημα για τη Γ΄, Δ΄, Ε΄ και ΣΤ΄ Τάξη του Δημοτικού Σχολείου με εστίαση στη διδασκαλία της λειτουργικής γραμματικής. / The purpose of this thesis is the teaching of the language in Primary School and in particular, the instruction method of the Greek language’s grammar. More specifically, the objective is to develop the concept of grammar and to put special emphasis on the teaching of functional grammar and subsequently on its effectiveness on students’ progress. In addition, the instruction of the functional grammar is associated with the development of instructional scenarios in regard to the linguistic subject. It is therefore attempted the design of some prime examples of instructional scenarios for the Third, Fourth, Fifth and Sixth Class of Primary School with a focus on the instruction of functional grammar.

Pagrindinis šio darbo tikslas yra sukurti energijos tiekimo saugumo trikdžių scenarijų matematinį modelį, kuriuo būtų galima modeliuoti įvairių galimų energetinių trikdžių scenarijus. Priklausomai nuo trikdžio sudėtingumo lygio jis gali neturėti visiškai jokios įtakos ir pasekmių arba priešingai – gali turėti labai didelę įtaką ir labai sunkias pasekmes energijos tiekimo saugumui. Todėl energetinio trikdžio įtaka ir pasekmės suskirstomi balais: nuo 0 (nėra pasekmių) iki 5 balų (labai sunkios pasekmės). Nagrinėjama to trikdžio įtaka įvairiems valstybės sektoriams: ekonominiui, socialiniui ir politiniui. Energetinio trikdžio įtaka ir sukeltos pasekmės ekonominiui, socialiniui ir politiniui sektoriams ir suprantamas kaip atskiras scenarijus. Energetiniam trikdžiui buvo suteikti parametrai ir su įvairiais parametrų rinkiniais sumodeliuoti 100 scenarijų. Iš tų scenarijų išrinktas pats tikėtiniausias, nustatyti sunkiausi (kritiniai) bei lengviausi (sukeliantys mažas pasekmes) scenarijai. Taip pat suskaičiuojamos tokių scenarijų tikimybės bei trikdžių pasirodymo tikimybės. Tam naudojami Markovo grandinės bei procesai ir tikimybiniai skirstiniai. / The main objective of this paper is to develop a mathematical model of energy supply disturbances for modelling energy supply disturbance scenarios. The level of energy supply disturbance depends on the impact it does to energy security of supply. The level of energy supply disturbance expressible with points: from 0 points (no impact) to 5 points (very heavy impact). It is analysed impact of this disturbance to different sectors of state: economical, social and political. The impact and caused damage of energy supply disturbance to economical, social and political sectors is understandable like a different scenario. Energy supply disturbance depends on different parameters. Scenarios of disturbances were modeled considering three parameters. For comparison there were developed 100 different long term energy supply disturbance scenarios. There were selected most common, most heavy (critical) and easiest scenarios, evaluated such scenarios probabilities and energy supply disturbance probabilities. In thia paper was used Markov chains and processes, probability distributions.

This paper presents a 3-Region footloose-entrepreneur new economic geography model. Two symmetric regions are part of an economically integrated area (the Union), while the third region represents an outside trade partner. We explore how the spatial allocation of industrial production and employment within the Union is affected by changes in two aspects of trade liberalisation: regional integration and globalisation. Our main contribution pertains to the analysis of the local and global dynamics of the specified factor mobility process. We show that significant parameter ranges exist for which asymmetric distribution of economic activities is one of the possible long-run outcomes. This is a remarkable result within the NEG literature. We then analyse the impact of international trade liberalisation on the dynamics of agglomeration conditional on the endowments of skilled and unskilled labour of the outside region. (authors' abstract) / Series: Department of Economics Working Paper Series

La question de l’évolution du parc nucléaire français peut être considérée via l’étude de scénarios électronucléaires. Ces études présentent un rôle important, compte-tenu des enjeux, de l’ampleur des investissements, des durées et de la complexité des systèmes concernés, et fournissent des éléments d’aide au processus décisionnel. Elles sont menées à l’aide du code COSI (développé au CEA/DEN), qui permet de calculer les inventaires et les flux de matières transitant dans le cycle (réacteurs nucléaires et installations associées), via notamment le couplage avec le code d’évolution CESAR. Les études actuelles menées avec COSI nécessitent de définir les paramètres d’entrée des scénarios simulés, de sorte à satisfaire différents critères comme minimiser la consommation d’uranium naturel, la production de déchets, etc. Ces paramètres portent notamment sur les quantités et l’ordonnancement des combustibles usés au retraitement ou encore le nombre, la filière et les dates de mises en service des réacteurs à déployer. Le présent travail vise à développer, valider et appliquer une méthodologie d’optimisation couplée à COSI pour la recherche de scénarios électronucléaires optimaux pour un problème multicritère. Cette méthodologie repose en premier lieu sur la réduction de la durée d’évaluation d’un scénario afin de permettre l’utilisation de méthodes d’optimisation en un temps raisonnable. Dans ce cadre, des métamodèles d’irradiation par réseaux de neurones sont établis à l’aide de la plateforme URANIE (développée au CEA/DEN) et sont implémentés dans COSI. L’objet du travail est ensuite d’utiliser, adapter et comparer différentes méthodes d’optimisation, telles que l’algorithme génétique et l’essaim particulaire disponibles dans la plateforme URANIE, afin de définir une méthodologie adéquate pour ce sujet d’étude spécifique. La mise en place de cette méthodologie suit une approche incrémentale qui fait intervenir des ajouts successifs de critères, contraintes et variables de décision dans la définition du problème d’optimisation. Les variables ajoutées au problème, qui décrivent la cinétique de déploiement des réacteurs et la stratégie de retraitement des combustibles usés, sont choisies en fonction de leur sensibilité sur les critères définis. Cette approche permet de faciliter l’interprétation des scénarios optimaux, la détection d’éventuelles difficultés liées au processus d’optimisation, et finalement d’émettre des recommandations d’utilisation de la méthodologie mise en place en fonction de la nature du problème. Les études d'optimisation s’appuient sur un scénario de déploiement de réacteurs à neutrons rapides avec recyclage du plutonium, inspiré des études menées dans le cadre de la loi de 2006 sur la gestion des matières et déchets radioactifs. Une illustration des possibilités de la méthodologie est réalisée sur ce scénario, et permet notamment de démontrer le caractère optimal du scénario issu des études menées selon cette loi vis-à-vis de la limitation de l’entreposage de matières fissiles. Ce résultat souligne l’importance de la mise en œuvre d’une gestion dynamique du plutonium via le recours au combustible MOX pour le déploiement progressif des RNR. / The issue of the evolution French nuclear fleet can be considered through the study of nuclear transition scenarios. These studies are of paramount importance as their results can greatly affect the decision making process, given that they take into account industrial concerns, investments, time, and nuclear system complexity. Such studies can be performed with the COSI code (developed at the CEA/DEN), which enables the calculation of matter inventories and fluxes across the fuel cycle (nuclear reactors and associated facilities), especially when coupled with the CESAR depletion code. The studies today performed with COSI require the definition of the various scenarios’ input parameters, in order to fulfil different objectives such as minimising natural uranium consumption, waste production and so on. These parameters concern the quantities and the scheduling of spent fuel destined for reprocessing, and the number, the type and the commissioning dates of deployed reactors.This work aims to develop, validate and apply an optimisation methodology coupled with COSI, in order to determine optimal nuclear transition scenarios for a multi-objective platform. Firstly, this methodology is based on the acceleration of scenario evaluation, enabling the use of optimisation methods in a reasonable time-frame. With this goal in mind, artificial neural network irradiation surrogate models are created with the URANIE platform (developed at the CEA/DEN) and are implemented within COSI. The next step in this work is to use, adapt and compare different optimisation methods, such as URANIE’s genetic algorithm and particle swarm methods, in order to define a methodology suited to this type of study. This methodology development is based on an incremental approach which progressively adds objectives, constraints and decision variables to the optimisation problem definition. The variables added, which are related to reactor deployment and spent fuel reprocessing strategies, are chosen according to their sensitivity to the defined objectives. This approach makes optimal scenarios interpretation easier, makes it possible to identify potential difficulties with the optimisation process, and then to provide recommendations on the use of the deployed methodology according to the problem type. The optimisation studies consider a fast reactor deployment scenario with plutonium recycling, which is inspired by studies carried out in the scope of the 2006 Act for Waste Management. An illustration of the possibilities of this methodology is provided with this scenario, demonstrating the optimality of the scenario inspired by the studies that were carried out for the 2006 Act, regarding stored fissile materials limitation. This result highlights the importance of dynamic plutonium management through MOX fuel usage during fast reactor deployment.