Ce travail de thèse porte sur le développement d'outils de modélisation pour le contrôle non destructif (CND) par courants de Foucault (CF). Il existe actuellement une tendance à la mise en œuvre de capteurs souples qui représentent une solution pertinente pour inspecter des pièces ayant une surface complexe. L'objectif principal de cette thèse est l'élaboration de techniques permettant la modélisation de ce type de capteurs au sein de la méthode des éléments finis (MEF).Lors de la modélisation d'un capteur souple avec la MEF, trois problématiques se manifestent. La première concerne le maillage des milieux fins qui apparaissent dans ce type de configuration (distance capteur-pièce contrôlée, bobine plate, revêtement fin...). Le maillage de ces régions par des éléments simpliciaux peut poser des problèmes numériques (éléments déformés quand un maillage grossier est considéré et grand nombre d'inconnues quand un maillage fin est utilisé). La deuxième problématique concerne le déplacement du capteur. Si les différents sous-domaines géométriques (air, pièce, capteur...) sont convenablement remaillés pour chaque position du capteur, le temps total pourra être pénalisant. La troisième problématique relative à la modélisation d'un capteur souple porte sur l'imposition du courant dans des bobines déformées.Une comparaison de différentes approches nous a conduit à retenir la méthode overlapping, qui permet de considérer simultanément des milieux fins avec maillages non-conformes. Cette méthode permet d'effectuer le recollement de deux surfaces non planes et/ou de géométries différentes. La méthode overlapping a été implantée dans deux formulations duales (magnétique et électrique) en 2D et 3D intégrées dans le code de calcul DOLMEN (C++) du LGEP. La méthode overlapping a été validée pour la prise en compte de plusieurs types de régions minces (air, milieux conducteurs, milieux magnétiques, bobines plates...). La modélisation des capteurs souples nécessite aussi l'implantation d'une technique permettant d'imposer correctement les courants dans un inducteur de forme arbitraire. Une technique a été sélectionnée et programmée, d'abord pour des bobines classiques (volumiques) déformées puis pour des bobines plates flexibles. Afin de valider les développements réalisés, différentes configurations de test ont été traitées et les résultats comparés avec des solutions de référence analytiques ou expérimentales.

<p>The tri-partite initiative in and for Africa has been accompanied by high levels of optimism since its political endorsement in 2008. It provides for an opportunity to resolve a host of problems with regards to regional integration in Eastern and Southern Africa. The overall aim of this study is to explore the prospects and challenges towards realising the Tri-partite Free Trade Area&nbsp / (T-FTA) in and for Africa. This study is pragmatic and implicitly seeks to uncover how the T-FTA could contribute to the African Regional Integration Project (ARIP), given the challenges that&nbsp / regional integration face in Africa. Regional integration has a long and rich history in Africa, which started at thehave been weak since the start and persist in its superficial nature with littledevelopmental impact. The reasons for the lack of meaningful integration in Africa are wide-ranging and span national, regional and system level analytical viewpoints. They encompass&nbsp / areas such as developmental levels, political will, respect for regional architecture, overlapping membership and the Economic Partnership Agreements (EPAs). These factors impact on the&nbsp / integration process in Africa and explain in varied ways why there has been little comprehensive economic integration. The starting point was to define the complex concept of regional integration. The dominant factors that define and affect regional integration in this study are that it is a state-based exercise, driven by economic integration, and influenced by the global political economy of the day. It was determined that Africa has adapted its regional integration strategies according to the shifts and influences in the global political economy on states,&nbsp / emanating from the post WWII period to the present day. The mpact of the global economy on Africa since independence was great and is viewed impact on the integration process. Regional integration is essentially a state to state&nbsp / pursuit for integration. Essentially, regional integration is being pursued by states that are still struggling to consolidate statehood, and this leaves little space to move towards a regional approach. However, given the dynamics of a globalised world, regional integration as a strategy is no longer questioned in Africa and is an important component of its developmental agenda. Clarifying the T-FTA was important, and this was done in order to highlight what the tri-partite initiative is and is not. This provided for an opportunity to&nbsp / investigate what the dominant areas are that have informed the emergence of the tri-partite process. The former was found to be largely economic in nature, focusing on harmonising the trade&nbsp / regimes of COMESA, EAC and SADC as a primary motivation. The tri-partite initiative will facilitate and encourage the harmonisation of trade regimes by stressing market integration,&nbsp / infrastructure development and industrialisation, coupled by a developmental approach. This is promising, as the tri-partite initiative seeks to simultaneously deal with many issues that have&nbsp / been commonly associated with the problems that regional integration face in Africa. When viewing the negotiating context, as well as the principles upon which it is to be based, indicate though, that Africa still favours individual state interest that will be hard to reconcile given that the tri-partite region currently has 26 participant states. In terms of economic integration, the T-FTA&nbsp / seeks to put new generation trade issues on the agenda by including services, movement of persons as well as trade facilitation, all of which have been found to be important in realising a&nbsp / trade in goods agenda that is the focus of regional integration in Africa. Analysing the grassroots realities of the market integration pillar offered some valuable insights towards the purposes&nbsp / of this study. The market integration pillar is inundated with challenges, with Rules of Origin (RoO) being the primary challenge towards consolidating the trade in goods agenda on a tri-partite&nbsp / level. New generation trade issues are going to be equally difficult to realise, given that they have no implementation record in the individual Regional Economic Communities (RECs). Promising though is that trade facilitation has already seen positive results by resolving non tariff barriers in the regions.Infrastructure development is equally challenging, although it provides&nbsp / a significant opportunity to create better connectivity (physical integration) between states. In lot of pan-African goals that directly feed into initiatives of the African Union (AU) pillar has not as yet created any concrete tri-partite plans, so it remains to be seen what can be achieved. Ideally, industrialisation is viewed as the pillar that will solve the supply-side constraints of African&nbsp / economies hence, strengthening the trade in goods agenda in the regions. Even though the T-FTA has practical challenges to implementation, there are at least two underlying factors that&nbsp / indirectly affect the prospects of realising the tripartite initiative. The EPAs are an emergent threat in that they run parallel to tripartite negotiations / and respect for a rules based integration process, are issues that warrant consideration. Fundamentally, in order to achieve a successful T-FTA will require a shift in the way business is done in African integration. African states need&nbsp / to realise that their national interests are best served through cooperation, in meaningful ways. Inevitably this requires good faith as well as ceding some sovereignty towards regional goals. Thus, there is a risk that the T-FTA not realised. The fundamentals of political will, economic polarisation and instability have to be resolved. This will lay an appropriate foundation for the&nbsp / tripartite initiative to be sustainable, with developmental impact. </p>

The capability to resolve the contributions from spectroscopically overlapping fluorophores has enabled significant breakthroughs in cellular imaging. However, commercial microscopes for this purpose use analog light detection with least squares curve-fitting analysis and improvements in sensitivity are needed. To this end, a microscope has been constructed with high throughput and single-photon detection capability. The fluorescence is separated through use of a prism spectrometer or a series of dichroic mirrors into four spectral bands and detected using four single-photon avalanche diode (SPAD) detectors, which provide high-quantum efficiency in the red spectral region. The detectors are connected to a time-correlated single photon counting module to provide sub-nanosecond temporal resolution for distinguishing fluorophores with different fluorescence lifetimes. Maximum-likelihood (ML) methods have been developed for analyzing the temporally and spectrally resolved photon count data from the SPADs to find the contributions from different fluorescent species and from background. Commercially available SPADs exhibit a count-rate dependent time shift in the impulse response function, and hence the instrument incorporates custom modified SPADs with improved timing stability. Nevertheless, there is still some time shift, and hence the ML-analysis has been extended to include this as an adjustable parameter for each individual SPAD. Monte Carlo simulations have also been developed to enable studies of the number of photons needed to resolve specific fluorophores.

Fisher’s adaptive sex ratio theory predicts that organisms should invest equally in sons and daughters and the sex ratio at conception should be 1:1. Hamilton’s theory predicts that organisms should adjust sex ratios based on the relative strength of competition within a mating group. Testing sex ratio and sex allocation theories requires variation in sex ratio. Different sex allocation and sex allocation adjustment mechanisms can produce skewed sex ratios. I used Tigriopus californicus, a harpacticoid copepod with extrabinomial variation in sex ratios, to test sex ratio evolution and socially-mediated sex determination. Using artificially selected sex-biased populations, the trajectory of population sex ratios were as expected under Fisher’s theory and sex ratios approached/reached 0.5 proportion males. Populations with overlapping generations had a slower rate of change towards 0.5 than populations with non-overlapping generations. I show that these data are supported by multiple different models: a mechanistic and simulation model. I tested socially-mediated sex determination using seawater conditioned with different local sex ratios of copepods. There were detectable effects found in both wild populations and isofemale lines. However, these effects may be trivial as differences were small between treatments. Sex determination in T. californicus is a complex mechanism, with multiple genetic and environmental components. The complex nature of sex determination in T. californicus and the dynamic nature of their habitat in highly ephemeral splash pools provide a possible explanation for the non-Fisherian sex ratios we see. / Graduate

Ένα από τα κύρια προβλήματα που συναντώνται σε κτίρια ή γέφυρες που έχουν κατασκευασθεί πριν από το 1980, είναι η μειωμένη καμπτική αντοχή και πλαστιμότητα, το οποίο αρκετά συχνά οφείλεται στην έλλειψη περίσφιξης και στη παρουσία κοντών αναμονών που είχαν οι κατασκευές αυτές. Ο κύριος σκοπός της παρούσας διατριβής είναι να παρουσιάσει και να αξιολογήσει πέντε από τα διαθέσιμα στη βιβλιογραφία αναλυτικά μοντέλα προσδιορισμού του απαιτούμενου πάχους του εξωτερικά εφαρμοζόμενου μανδύα για την αποφυγή της αστοχίας των ματιζομένων οπλισμών των υποστυλωμάτων συμπεριλαμβανομένου και του αντίστοιχου μοντέλου το οποίο δίνεται στο Σχέδιο 1 και Σχέδιο 2 του ΚΑΝΕΠΕ. Τα αναλυτικά μοντέλα αξιολογούνται μέσω πειραματικών αποτελεσμάτων από τη βιβλιογραφία. Η αξιολόγηση γίνεται σε δύο επίπεδα. Στο πρώτο επίπεδο αξιολογείται η αξιοπιστία πρόβλεψης του απαιτούμενου πάχους του υλικού ενίσχυσης –χρησιμοποιώντας τις μέσες τιμές των υλικών- ενώ στο δεύτερο επίπεδο εξετάζεται η αντίστοιχη καταλληλότητα κάθε προσομοιώματος για το σχεδιασμό –χρησιμοποιώντας τις αντίστοιχες τιμές σχεδιασμού των υλικών-. Τροποποιημένες εξισώσεις βασιζόμενες στο προσομοίωμα του ΚΑΝΕΠΕ παρουσιάζονται. Η χρήση των τροποποιημένων εξισώσεων ελέγχεται μέσω διαθέσιμων πειραματικών αποτελεσμάτων και προκύπτει ικανοποιητική σύγκλιση με αυτά. / Reinforced concrete frames or bridges constructed in the early 80s or before, were usually designed and detailed to resist lower lateral forces than those required today. Building columns were commonly designed for compression only and as a result they do not have the adequate lateral strength to resist the imposed earthquake loads. One of the main deficiencies in these older structures is the limited flexural strength and ductility often due to short and lightly confined lap splices. The main aim of this thesis is to present and evaluate five of the proposed analytical models in order to rehabilitate reinforced concrete columns with short lap splices by external confinement, including and the confinement model given by the draft version of the Greek Retrofitting Code (GRECO). The above analytical models are validated against experimental results. The validation is performed in two levels. In the first level, the reliability of the prediction for the required jacket thickness given by the models, is examined, by using the average values of the materials. In the second level, the propriety for the design of each model is examined by using the design values of the materials. A modified equation based on the model given by GRECO is presented as well. By using the proposed modified equation a satisfactory agreement with the experimental results was accomplished.

<p>The tri-partite initiative in and for Africa has been accompanied by high levels of optimism since its political endorsement in 2008. It provides for an opportunity to resolve a host of problems with regards to regional integration in Eastern and Southern Africa. The overall aim of this study is to explore the prospects and challenges towards realising the Tri-partite Free Trade Area&nbsp / (T-FTA) in and for Africa. This study is pragmatic and implicitly seeks to uncover how the T-FTA could contribute to the African Regional Integration Project (ARIP), given the challenges that&nbsp / regional integration face in Africa. Regional integration has a long and rich history in Africa, which started at thehave been weak since the start and persist in its superficial nature with littledevelopmental impact. The reasons for the lack of meaningful integration in Africa are wide-ranging and span national, regional and system level analytical viewpoints. They encompass&nbsp / areas such as developmental levels, political will, respect for regional architecture, overlapping membership and the Economic Partnership Agreements (EPAs). These factors impact on the&nbsp / integration process in Africa and explain in varied ways why there has been little comprehensive economic integration. The starting point was to define the complex concept of regional integration. The dominant factors that define and affect regional integration in this study are that it is a state-based exercise, driven by economic integration, and influenced by the global political economy of the day. It was determined that Africa has adapted its regional integration strategies according to the shifts and influences in the global political economy on states,&nbsp / emanating from the post WWII period to the present day. The mpact of the global economy on Africa since independence was great and is viewed impact on the integration process. Regional integration is essentially a state to state&nbsp / pursuit for integration. Essentially, regional integration is being pursued by states that are still struggling to consolidate statehood, and this leaves little space to move towards a regional approach. However, given the dynamics of a globalised world, regional integration as a strategy is no longer questioned in Africa and is an important component of its developmental agenda. Clarifying the T-FTA was important, and this was done in order to highlight what the tri-partite initiative is and is not. This provided for an opportunity to&nbsp / investigate what the dominant areas are that have informed the emergence of the tri-partite process. The former was found to be largely economic in nature, focusing on harmonising the trade&nbsp / regimes of COMESA, EAC and SADC as a primary motivation. The tri-partite initiative will facilitate and encourage the harmonisation of trade regimes by stressing market integration,&nbsp / infrastructure development and industrialisation, coupled by a developmental approach. This is promising, as the tri-partite initiative seeks to simultaneously deal with many issues that have&nbsp / been commonly associated with the problems that regional integration face in Africa. When viewing the negotiating context, as well as the principles upon which it is to be based, indicate though, that Africa still favours individual state interest that will be hard to reconcile given that the tri-partite region currently has 26 participant states. In terms of economic integration, the T-FTA&nbsp / seeks to put new generation trade issues on the agenda by including services, movement of persons as well as trade facilitation, all of which have been found to be important in realising a&nbsp / trade in goods agenda that is the focus of regional integration in Africa. Analysing the grassroots realities of the market integration pillar offered some valuable insights towards the purposes&nbsp / of this study. The market integration pillar is inundated with challenges, with Rules of Origin (RoO) being the primary challenge towards consolidating the trade in goods agenda on a tri-partite&nbsp / level. New generation trade issues are going to be equally difficult to realise, given that they have no implementation record in the individual Regional Economic Communities (RECs). Promising though is that trade facilitation has already seen positive results by resolving non tariff barriers in the regions.Infrastructure development is equally challenging, although it provides&nbsp / a significant opportunity to create better connectivity (physical integration) between states. In lot of pan-African goals that directly feed into initiatives of the African Union (AU) pillar has not as yet created any concrete tri-partite plans, so it remains to be seen what can be achieved. Ideally, industrialisation is viewed as the pillar that will solve the supply-side constraints of African&nbsp / economies hence, strengthening the trade in goods agenda in the regions. Even though the T-FTA has practical challenges to implementation, there are at least two underlying factors that&nbsp / indirectly affect the prospects of realising the tripartite initiative. The EPAs are an emergent threat in that they run parallel to tripartite negotiations / and respect for a rules based integration process, are issues that warrant consideration. Fundamentally, in order to achieve a successful T-FTA will require a shift in the way business is done in African integration. African states need&nbsp / to realise that their national interests are best served through cooperation, in meaningful ways. Inevitably this requires good faith as well as ceding some sovereignty towards regional goals. Thus, there is a risk that the T-FTA not realised. The fundamentals of political will, economic polarisation and instability have to be resolved. This will lay an appropriate foundation for the&nbsp / tripartite initiative to be sustainable, with developmental impact. </p>

Die kontinuumsmechanische Untersuchung der Lastübertragungsmechanismen zwischen den Rovings im textilbewehrten Feinbeton trägt wesentlich zum Gesamtverständnis des mechanischen Verhaltens des Verbundmaterials bei. Neben der Erfassung der gegenseitigen Beeinflussung sich kreuzender Rovings erfordert insbesondere die mechanische Modellierung und numerische Simulation von Bewehrungsstößen und Endverankerungen die Kenntnis dieser Übertragungsmechanismen. Die numerischen Simulationen sollen u. a. zeigen, welche Endverankerungslängen und welche Übergreifungslängen an Bewehrungsstößen erforderlich sind und wie die Querbewehrung die Rissbildung beeinflusst. / This paper concerns with the investigation of stress transfer mechanisms between yarns and concrete matrix and their influence on the overall behavior of textile reinforced concrete (TRC). This investigation considers textile reinforcement splices and textile reinforcement development lengths and carried out by means of Finite-Element simulations and fracture mechanic approaches. A first modeling procedure is made towards analyzing and investigating the damage mechanisms in TRC specimen under tension loading which are mainly characterized by matrix cracking and yarn pullout. This modeling approach allows for considering the yarn crack bridging which is a main characteristic behavior of TRC. In the same manner, 3D Finite-Element models are conducted for calculating the required reinforcement development lengths and the reinforcement overlapping lengths. The conducted approach takes into account different damage mechanisms observed in the corresponding experimental investigations which are also used for calibrating the modeling procedures. Moreover, the presented approach covers a wide range of required textile reinforcement overlapping lengths and development lengths and provides the corresponding ultimate loads.

Norges Handelshøyskole, Diss.--Bergen, 2007. / Enth. 4 Beitr.

Universiẗat, Diss.--Würzburg, 2007.

Univ., Diss--Bielefeld, 2007.