The dependence on oil and the fact that petroleum conventional reservoirs are becoming depleted direct attentions toward unconventional-and harder to access-reservoirs. Among those, heavy and extremely heavy oil reservoirs and tar sands form a considerable portion of all petroleum resources. Conventional thermal and thermocatalytic refining methods are not affordable choices in some cases, as they demand a considerable energy investment. On the other hand, electron irradiation, as a novel technology, provides more promising results in heavy oil upgrading. Electron irradiation, as a method of delivering energy to a target molecule, ensures that most of the energy is absorbed by the molecule electronic structure. This leads to a very efficient generation of reactive species, which are capable of initiating chemical reactions. In contrast, when using thermal energy, only a small portion of the energy goes into the electronic structure of the molecule; therefore, bond rupture will result only at high energy levels. The effect of electron irradiation on different heavy petroleum fluids is investigated in this study. Radiation-induced physical and chemical changes of the fluids have been evaluated using different analytical instruments. The results show that high energy electron particles intensify the cracking of heavy hydrocarbons into lighter species. Moreover, irradiation is seen to limit any post-treatment reactions, providing products of higher stability. Depending on the characteristics of the radiolyzed fluid, irradiation may change the distribution pattern of the products, or the radiolysis process may follow the same mechanism that thermal cracking does. In addition to that, we have studied the effectiveness of different influencing variables such as reaction temperature, absorbed dose values, and additives on radiolytic reactions. More specifically, the following subjects are addressed in this study: *Radiation?induced chain reactions of heavy petroleum fluids *Complex hydrocarbon cracking mechanism *High and low temperature radiolysis *Synergetic effects of different chemical additives in radiolysis reactions *Time stability of radiation products

Αντικείμενο της παρούσας διπλωματικής εργασίας, είναι η μελέτη της συμπεριφοράς φωτοβολταϊκού πλαισίου λεπτής ταινίας CIS, σε πραγματικές συνθήκες λειτουργίας. Μελετάται η επίδραση διάφορων εξωτερικών παραγόντων και κυρίως της θερμοκρασίας, της ηλιακής ακτινοβολίας και της σκίασης. Με στόχο την εκτίμηση της παραγόμενης DC ισχύος σε διάφορες συνθήκες λειτουργίας., έχουν πραγματοποιηθεί μετρήσεις ρεύματος-τάσης στο χώρο του Πανεπιστημίου Πατρών, σε φωτοβολταϊκό πλαίσιο CIS ονομαστικής ισχύος 75W. Οι μετρήσεις ήταν συνήθως ημερήσιες και καταγράφονταν οι τιμές για διάφορες συνθήκες λειτουργίας και σε διαφορετικές εποχές του έτους. Με ένα μεταβλητό φορτίο συνδεδεμένο με το εν λόγω φωτοβολταϊκό πλαίσιο, ήταν δυνατός ο προσδιορισμός της χαρακτηριστικής I-V καμπύλης σε κάθε μέτρηση και ως εκ τούτου, ο υπολογισμός του σημείου μέγιστης ισχύος. Για κάθε μέτρηση καταγράφονταν, εκτός του ρεύματος και της τάσης, η λαμβανόμενη ηλιακή ακτινοβολία, η θερμοκρασία αέρα καθώς και οι θερμοκρασίες στις δύο όψεις του συλλέκτη. Αρχικά, υπολογίζεται η απόδοση του πλαισίου σε διαφορετικές θερμοκρασίες λειτουργίας ενώ σε αυτό προσπίπτουν ίδια ποσά της ηλιακής ακτινοβολίας. Επίσης, μελετάται ποιες χαρακτηριστικές παράμετροι επηρεάζονται περισσότερο όπου διαπιστώνεται πως η αύξηση της θερμοκρασίας προκαλεί μείωση της τάσης και μία μικρή αύξηση του ρεύματος η οποία όμως, δεν είναι ικανή να αντισταθμίσει την μείωση της τάσης, με αποτέλεσμα η αύξηση της θερμοκρασίας να επιδρά αρνητικά στην απόκριση ισχύος. Στη συνέχεια, γίνεται αντίστοιχος υπολογισμός και για την ηλιακή ακτινοβολία όπου παρουσιάζεται η θετική της επίδραση στην απόδοση του πλαισίου, ενώ ταυτόχρονα μελετάται η συμπεριφορά του CIS σε συνθήκες ηλιοφάνειας αλλά και συννεφιάς. Κατά την επεξεργασία των αποτελεσμάτων αυτών, ήταν δυνατός ο υπολογισμός μίας μέσης τιμής της αποδιδόμενης ισχύος τόσο για τη θερινή όσο και για τη χειμερινή περίοδο. Τέλος, προκαλώντας τεχνητή σκίαση στο 30% περίπου της επιφάνειας του φωτοβολταϊκού πλαισίου κατά τη διάρκεια κάποιων μετρήσεων, υπολογίζεται το ποσοστό μείωσης της παραγόμενης DC ισχύος, συγκριτικά με τις περιπτώσεις όπου κάτω από τις ίδιες εξωτερικές συνθήκες, το πλαίσιο δεν σκιάζεται. / The objective of this diploma thesis, is to study the behavior of a thin film photovoltaic module CIS, under real conditions of operation. The effect of various exterior factors is studied and mainly the factors of temperature, solar radiation and shading. To estimate the produced DC Power in various conditions, measurements has been took place at the University of Patras using a CIS photovoltaic module, of 75W Maximum Power. Measurements were usually daily and were taken in all seasons of year. With a variable load connected to the photovoltaic module, the determination of the I-V curve was possible for each measurement and consequently, the calculation of the Maximum Power Point could be made. At each measurement, were noted the current, the voltage and also the received solar radiation, the air temperature as well as the temperatures at the two sides of the module. At first, the output and the efficiency of the module in different temperatures of operation are calculated , while the received solar radiation is the same in every case. Also, it is studied witch parameters are more influenced by increasing temperature and it is proved that voltage is decreased and current is a little increased. However, the increasing current is not capable to compensate the decreasing voltage, so the increase of temperature affects negatively the output power and the efficiency. Afterwards, a similar calculation has been made, studying the influence of solar radiation at the characteristic parameters of the CIS photovoltaic module. During these calculations, except the positive effect of solar radiation it is presented the behavior of CIS in sunlight and also cloudy conditions. As a result, an average output power of the module has calculated for the aestival and the wintry period. Finally, causing artificial shading in about the 30% of the module's surface, it is determined the rate of reduction of produced DC power, comparatively the case where the module is not shading under the same exterior conditions.

Structural Health Monitoring (SHM) is a promising tool for condition assessment of bridge structures. SHM of bridges can be performed for different purposes in long or short-term. A few aspects of short- and long-term monitoring of highway bridges are addressed in this research. Without quantifying environmental effects, applying vibration-based damage detection techniques may result in false damage identification. As part of a long-term monitoring project, the effect of temperature on vibrational characteristics of two continuously monitored bridges are studied. Natural frequencies of the structures are identified from ambient vibration data using the Natural Excitation Technique (NExT) along with the Eigen System Realization (ERA) algorithm. Variability of identified natural frequencies is investigated based on statistical properties of identified frequencies. Different statistical models are tested and the most accurate model is selected to remove the effect of temperature from the identified frequencies. After removing temperature effects, different damage cases are simulated on calibrated finite-element models. Comparing the effect of simulated damages on natural frequencies showed what levels of damage could be detected with this method. Evaluating traffic loads can be helpful to different areas including bridge design and assessment, pavement design and maintenance, fatigue analysis, economic studies and enforcement of legal weight limits. In this study, feasibility of using a single-span bridge as a weigh-in-motion tool to quantify the gross vehicle weights (GVW) of trucks is studied. As part of a short-term monitoring project, this bridge was subjected to four sets of high speed, live-load tests. Measured strain data are used to implement bridge weigh-in-motion (B-WIM) algorithms and calculate the corresponding velocities and GVWs. A comparison is made between calculated and static weights, and furthermore, between supposed speeds and estimated speeds of the trucks. Vibration-based techniques that use finite-element (FE) model updating for SHM of bridges are common for infrastructure applications. This study presents the application of both static and dynamic-based FE model updating of a full scale bridge. Both dynamic and live-load testing were conducted on this bridge and vibration, strain, and deflections were measured at different locations. A FE model is calibrated using different error functions. This model could capture both global and local response of the structure and the performance of the updated model is validated with part of the collected measurements that were not included in the calibration process.

No description available.

The inverted T-beam bridge system provides an accelerated bridge construction alternative for short-to-medium-span bridges. The system consists of adjacent precast inverted T-beams finished with a cast-in-place concrete topping. The system offers enhanced performance against reflective cracking, and reduces the likelihood of cracking due to time dependent effects. The effects of transverse bending due to concentrated wheel loads are investigated with respect to reflective cracking. Transverse bending moment are quantified and compared to transverse moment capacities provided by a combination of various cross-sectional shapes and transverse connections. A design methodology for transverse bending is suggested. Tensile stresses created due to time dependent and temperature effects are quantified at the cross-sectional and structure level and strategies for how to alleviate these tensile stresses are proposed. Because differential shrinkage is believed to be one of the causes of deck cracking in composite bridges, a study on shrinkage and creep properties of seven deck mixes is presented with the goal of identifying a mix whose long terms properties reduce the likelihood of deck cracking. The effects of differential shrinkage at a cross-sectional level are numerically demonstrated for a variety of composite bridge systems and the resistance of the inverted T-beam system against time dependent effects is highlighted. End stresses in the end zones of such a uniquely shaped precast element are investigated analytically in the vertical and horizontal planes. Existing design methods are evaluated and strut-and-tie models, calibrated to match the results of 3-D finite element analyses, are proposed as alternatives to existing methods to aid designers in sizing reinforcing in the end zones. Composite action between the precast beam and the cast-in-place topping is examined via a full scale test and the necessity of extended stirrups is explored. It is concluded that because of the large contact surface between the precast and cast-in-place elements, cohesion alone appears to provide the necessary horizontal shear strength to ensure full composite action. Live load distribution factors are quantified analytically and by performing four live loads tests. It is concluded that AASHTO's method for cast-in-place slab span bridges can be conservatively used in design. / Ph. D.

L’étude de la durabilité des élastomères des stators des pompes Moineau a été menée en utilisant à la fois des simulations numériques, des essais thermomécaniques et des analyses physico-chimiques. Les simulations numériques ont eu pour principal objectif de permettre de déterminer la localisation et le niveau des maximums des champs mécaniques dans le stator. Les essais ont permis quant à eux de caractériser le comportement mécanique du matériau élastomère sous sollicitations mécaniques cycliques à différentes températures. Une première étude a permis d’analyser l’évolution de l’effet Payne en fatigue. Une seconde s’est concentrée sur l’analyse de l’effet de l’application d’un chargement thermomécanique sur l’évolution de la microstructure du matériau élastomère. / The study of the sustainability of the rubber, which is the main constitutive material of the Moineau pump stator, was carried out using finite element analyses, thermomechanical experiments and physic-chemical analysis. The numerical simulations were performed to identify the range and location of the maximal stress and strain within the pump stator. The experimental tests allowed to characterize the mechanical behaviour of rubber under cyclic solicitation at several temperatures. The first part of the study focused on the Payne effect during fatigue loading while the second dealt with the effect of a thermomechanical loading on the rubber microstructure evolution.

[pt] O presente trabalho apresenta um estudo do comportamento mecânico de um solo argiloso e um solo residual, submetidos a ensaios com temperaturas entre 20ºC e 70ºC. O programa experimental envolveu ensaios de caracterização (limites de Atterberg), ensaios de adensamento com carregamento incremental (SIC), triaxiais não drenados (CIU) e de cisalhamento direto. Para a realização dos ensaios de limites de Atterberg, as amostras foram previamente aquecidas em estufa. Para a realização dos ensaios de adensamento, triaxiais e de cisalhamento direto, foram desenvolvidos sistemas de aquecimento, controle e distribuição térmica, para garantir ao corpo de prova uma uniformidade da temperatura preestabelecida. Uma metodologia de calibração do sistema de aquecimento foi desenvolvida para se determinar o tempo necessário para o equilíbrio térmico dos solos. Houve também a preocupação com a calibração prévia dos instrumentos eletrônicos da prensa triaxial (transdutores e célula de carga) na temperatura dos ensaios. Na faixa de temperatura estudada, o preaquecimento não têm influência nos resultados de limites do solo argiloso. Os ensaios de adensamento revelaram que o aquecimento leva a um aumento da compressibilidade do solo, assim como um aumento da velocidade de adensamento. Nos ensaios triaxiais, observou-se que o aumento da temperatura causa um aumento da resistência dos materiais, além de reduzir o excesso de poropressões gerado durante o cisalhamento não drenado. Os ensaios de cisalhamento direto confirmaram a tendência de aumento da resistência observada nos ensaios triaxiais, além de indicar uma redução da deformabilidade volumétrica durante o cisalhamento. / [en] The subject matter of this thesis is the study of the mechanical behavior of clay and residual soils subjected to a series of tests with temperatures ranging from 20 to 70ºC. The experimental program consisted of Atterberg limits, consolidation tests with incremental loading (SIC), triaxial consolidated undrained tests (CIU) and direct shear tests on both soil types under saturated conditions. Samples for Atterberg limit tests have been pre-heated in oven to the specified temperature. Heating control and thermal distribution systems have been specially developed for insuring an homogeneous temperature throughout the consolidation, triaxial and direct shear tests. The thermal balance times for the two soils were achieved by means of a calibration method developed for the heating system. Transducers and load cell calibration were carefully calibrated acording to the temperature range for the testing program. It may be concluded that pre-heating to temperatures below 70ºC has no influence on the Atterberg limits results for both soils. Consolidation tests have shown that heating on samples leads to an increase in compressibility and also on the coefficient of consolidation. From the triaxial tests it was observed that an increase in temperature leads to an increase in strength and to smaller excess porepressures during undrained shear tests. The increase in shear strenght with temperature observed on triaxial tests was also confirmed by direct shear tests. These effects were more significant in clay than in residual soil.

Les agrégats de molécules d'eau constituent une classe d'espèces chimiques importante du fait de leur rôle central dans de nombreux processus physico-chimiques et biologiques terrestres, en particulier, les processus atmosphériques. Leurs propriétés physiques et chimiques sont particulièrement sensibles aux effets de taille et aux effets de température, ce qui les rend particulièrement difficile à caractériser expérimentalement. Ainsi, mes travaux de thèse ont porté sur l'étude théorique des propriétés structurales, dynamiques et thermodynamiques ainsi que sur la réactivité de divers agrégats de molécules d'eau avec pour objectif de mettre en place des outils de modélisation adaptés, permettant une description plus fine de ces systèmes. Pour cela, nous avons utilisé des approches de dynamique moléculaire de type "parallel-tempering" qui ont été couplées avec des calculs d'énergie et de gradient réalisés par la méthode Self-Consistent-Charge Density-Functional based Tight-Binding (SCC-DFTB). Trois grands volets ont été abordés au cours de ces travaux. Dans la première partie, l'analyse détaillée des structures des agrégats d'eau (H2O)nSO24- et (H2O)nH2SO4 avec n=1-20 est présentée. Nous avons mis en évidence l'influence de la nature de l'impureté soufrée sur le réseau de liaisons hydrogène de ces agrégats. La deuxième partie de cette thèse porte sur l'étude de la transition de phase "solide-liquide" dans divers agrégats de molécules d'eau. En plus des agrégats soufrés évoqués ci-dessus, nous avons également étudié des agrégats d'eau protonés contenant de 19 à 23 molécules d'eau. Pour mieux comprendre le mécanisme de transition de phase, nous avons considéré divers changements structuraux associés à la transition tels que l'évolution des distributions d'angles intermoléculaires et l'évolution du nombre de cycles de molécules dans l'agrégat. Nous avons également caractérisé la transition de phase au travers d'indicateurs dynamiques tels que la fréquence de transfert du proton en excès. La dernière partie de cette thèse est consacrée à l'étude de l'influence de petits agrégats d'eau (allant de 1 à 10 molécules d'eau) sur la réaction de recombinaison entre l'atome H et la molécule CO. Cette réaction est la première étape de formation des molécules organiques oxygénées simples dans le milieu interstellaire. Elle présente donc un intérêt particulier. Grâce à l'analyse de dynamiques collisionnelles entre H et CO ainsi qu'au calcul de sections efficaces de réaction, nous avons montré que la présence des molécules d'eau joue un rôle important dans le processus de formation du radical HCO. / Water clusters constitute an important class of chemical species due to their central role in many physico-chemical and biological processes, in particular, atmospheric processes. Their physical and chemical properties are particularly sensitive to size and finite-temperature effects, which makes them particularly difficult to characterize experimentally. This thesis focused on the theoretical investigation of the structural, dynamical and thermodynamical properties as well as on the reactivity of various water clusters with the aim to implement appropriate modeling tools to enable a more detailed description of these systems. To do so, we used the paralleltempering molecular dynamics approach that was coupled with calculations of energies and gradients carried out by the Self-Consistent-Charge Density-Functional based Tight-Binding (SCC-DFTB) method.Three main areas were addressed during the work. In the first part, a detailed analysis of the structure of water clusters (H2O)nSO24- and (H2O)nH2SO4 with n=1-20 is performed. This study highlights the influence of the nature of the sulfur impurity on the hydrogen bond network of these species.The second part of this thesis focuses on the study of the "solid-liquid" phase transition in various water clusters. In addition to the sulfur-containing water clusters mentioned above, we also investigated protonated water clusters containing from 19 to 23 water molecules. To better understand the phase transition mechanism, we considered various structural changes associated with the transition, such as the evolution of the distributions of intermolecular angles and the evolution of the number of molecular rings in the cluster. We also characterized the phase transition through dynamical indicators such as the crossover frequency of the excess proton. The last part of this thesis is devoted to the study of the influence of small water clusters (from 1 to 10 water molecules) on the recombination reaction between the H atom and the CO molecule. This reaction is the first step in the formation of simple oxygenated organic molecules in the interstellar medium. It is therefore of particular interest. Due to the analysis of collisional dynamics between H and CO and the calculation of effective reaction cross sections we showed that the presence of water molecules plays an important role in the HCO radical formation.

Le principal objectif de ce travail est d’étudier les cellules solaires organiques de type hétérojonction en volume à l’aide d’un modèle bidimensionnel spécifique incluant un état intermédiaire pour la dissociation des charges dans les matériaux organiques. Ce modèle est mis en place dans un logiciel de simulation par éléments finis. Après validation, il est comparé à deux approches existant dans la littérature. Le grand nombre de paramètres requis pour décrire le mécanisme complexe de génération de charges nécessite un algorithme robuste, basé sur l’exploitation de chaînes de Markov, pour extraire ces paramètres physiques à partir de données expérimentales. Le modèle ainsi que la procédure d’extraction de paramètres sont utilisés dans un premier temps pour étudier le mécanisme de dissociation associé à une cellule comportant une nouvelle molécule. Ensuite le comportement en température de cellules à base de P3HT : PCBM est simulé et comparé à des mesures expérimentales. / The main objective of this work is to study bulk heterojunction organic solar cells with a specific two dimensional model that takes into account an intermediate state specific to organic materials. The model is solved numerically by a finite element software. After its validation, it is compared to two existing approaches in the literature. The large number of parameters needed to describe the complex charge generation mechanism requires a robust parameter extraction algorithm, based on the operation of Markov chains, in order to extract these physical parameters from experimental characterizations. The model and the parameter extraction method are then used to study the charge dissociation mechanism of a cell with a newly synthesized molecule. Finally, the temperature evolution of P3HT : PCBM solar cells are simulated and compared to experimental measurements.

Dans ce travail de thèse, nous avons étudié l'effet des rayonnements ionisants (rayons X et γ) jusqu'à une dose maximale de 1 Grad sur différents types de fibres multimodes (dopées -P, -P-Ce, -Ge, -Ge-F, -Ge-Ce et -N). Les caractérisations ont été réalisées principalement avec trois techniques expérimentales : online Atténuation Induite par Radiation en temps réel (RIA), Résonance Paramagnétique Electronique (EPR), Micro-Luminescence (ML). Dans la première partie du travail de cette thèse, nous avons étudié la réponse aux radiations de différents types de fibres optiques. L'absorption liée aux défauts du phosphore induits par irradiation a été étudiée par des mesures RIA dans le domaine spectral UV-Visible. Les mesures EPR nous permis de détecter les défauts POHC, P1 et P2. En particulier, pour la détection de P1 et P2, nous avons utilisé le mode de détection de la seconde harmonique pour déterminer la cinétique de croissance des P1 et P2 en fonction de la dose. Nous avons également étudié les effets dus au changement des conditions de fibrage et ceux liés à la variation de la température d'irradiation (25-280 ° C). Nous avons aussi étudié l’effet du codopage du coeur de la fibre avec du Cérium. Dans ce cas, nous avons observé une production moins importante de centres POHC et P2 sous irradiation. De plus, les mesures EPR ont montré que la génération des défauts P1 n’est pas sensiblement influencée par le codopage avec le Cérium. En ce qui concerne les fibres optiques dopées Ge, on a étudié trois types de dopage : Ge seul, co-dopage Ge-F et Ge-Ce. Pour chaque type, nous avons examiné trois conditions de fibrage. La réponse à l’irradiation de ces fibres a été étudiée par les trois techniques utilisées. Plus particulièrement la ML, nous a permis d'obtenir une vision plus complète du rôle du codopant et des précurseurs dans la formation des défauts induits par l'irradiation. Nous avons également étudié la réponse au rayonnement de la fibre dopée N avec trois différentes conditions de fibrage. Les réponses à l’irradiation dans les régions spectrales UV-visible ont été obtenues par des mesures RIA. Par EPR, nous avons pu détecter deux défauts liés à l'azote pour les doses élevées de radiation. Enfin, les mesures ML sur les fibres irradiées ont montré trois bandes d'émission dans le visible qui ont été attribuées clairement à des centres émetteurs liés à l'azote. Dans la deuxième partie de la thèse, nous avons étudié les effets liés au chargement en oxygène des fibres étudiées. Par des mesures en microspectroscopie Raman, nous démontrons qu'un traitement à haute température et haute pression peut favoriser l’introduction d’une grande quantité de O2 dans les fibres optiques à cœur de silice pure (PSC) ou dopées F, Ge ou P. Les réponses à l’irradiation de certaines des fibres optiques chargées en O2 ont été étudiés (et en particulier PSC et celle dopée F. Sur la base des données de la littérature, nous avons effectué les décompositions des spectres RIA en fonction de la dose. De plus, l'étude EPR des fibres optiques dopées P et chargées en O2 a montré une forte réduction des défauts P1 et P2 comparées aux fibres non traitées. Dans cette partie de la thèse, j’ai également présenté les résultats concernant la radioluminescence infrarouge (1272 nm) des molécules O2 dans la fibre optique. La faisabilité d'un capteur de radiation pour des environnements sous fortes doses et forts débits de dose a été discutée / In this Thesis work we have investigated the effect of ionizing irradiation (X and γ rays) up to 1 Grad on different types of multimode optical fibers (P-doped, P-Ce-doped , Ge-doped, Ge-F-doped, Ge-Ce-doped, and N-doped). The experiments were carried out by three main experimental techniques: online Radiation Induced Attenuation (RIA), Electron Paramagnetic Resonance (EPR) and Confocal Micro-Luminescence (CML). In the first part of the Thesis work we report on the radiation response of several types of optical fibers. The absorption due to radiation induced P-related defects was studied by RIA in the UV-Visible domain. Moreover, by EPR measurements we were able to detect POHC, P1 and P2 defects. In particular, for the detection of P1 and P2 defects we have validated the use of EPR second-harmonic detection mode which allowed us to obtain the growth kinetics of P1 and P2 with the dose. The effects due to the variation of the drawing conditions of the fibers were investigated as well as the ones due to the change of the temperature of irradiation (from 25 to 280 °C). Finally, concerning the P-doped OFs, we report on the effects due to the Cerium codoping of the core of the optical fiber. We observed a reduced generation of POHC and P2 centers under irradiation. However, EPR investigation has shown that the generation of P1 defects is essentially unaffected by the Ce-codoping. Regarding Ge-doped optical fibers we report on three basic typologies: Ge-doped, Ge-F-doped and Ge-Ce-doped. For each fiber typology we investigated three drawing conditions. The radiation responses of these fibers were characterized by RIA and EPR measurements. Furthermore, performing CML measurements we were able to obtain further insight on the role of the co-dopants and of the defect precursors in determining the radiation induced defects. We have also investigated the radiation response of N-doped OFs (three drawing conditions). The radiation responses in the UV-Visible domains were obtained by RIA, and by EPR measurements we were able to detect the signals of two N-related defects at high radiation doses. Finally, CML measurements on irradiated samples have shown three emission bands in the visible domain which are tentatively assigned to N-related centers. In the second part of the Thesis we report on the effects of an O2 loading treatment produces on some of the investigated samples. By micro-Raman measurements we demonstrate that a high pressure high temperature treatment can incorporate high quantity of O2 into Pure-Silica-Core (PSC), F, Ge and P doped optical fibers. The radiation responses of some of the O2-loaded optical fibers were investigated with particular regard to the fluorine doped and pure-silica-core optical fibers. On the basis of literature data we performed band decompositions of the RIA spectra as a function of the dose. Moreover, the EPR study of the O2 loaded P-doped optical fiber have shown a strong reduction of the signals associated to the P1 and P2 defects as compared to the untreated fibers. In this part of the thesis we also report on the characterization of the near infrared radioluminescence (1272 nm) of O2 molecules embedded in the optical fiber matrix and the feasibility of a radiation sensor based on this phenomenon for environments characterized by high radiation doses and high dose-rates