L’objet de ce travail est le développement de méthodologies et d’équipements Raman performants, permettant d’accéder aux propriétés des matériaux en conditions extrêmes. Nous décrivons la conception d’un spectromètre Raman portable original, dédié aux mesures in situ dont la sonde versatile permet d’obtenir une caractérisation Raman en conditions extrêmes, offrant une large gamme de longueurs d’ondes d’excitation, et des optiques de collections permettant d’obtenir un signal Raman dans un très grand nombre d’environnements sévères aux accès optiques délicats. De plus, la technique Raman est couplée à des mesures de microluminescence (cathodo/iono/photoluminescence), et ce, au même point de l’échantillon. Le système permet également -via un détecteur CCD intensifié- la caractérisation résolue en temps par spectroscopies Raman et de luminescence, associée à un mode pulsé de l’accélérateur, donnant accès à de nombreuses informations complémentaires sur la structure de l’échantillon. Enfin, ce dispositif donne accès à l’étude des propriétés des matériaux en conditions de haute température et d’irradiation. D’autre part, les systèmes d’analyses ex-situ en conditions extrêmes sont détaillés dans ce travail. Les principaux résultats acquis sont également présentés afin d’illustrer le fonctionnement et la qualité des résultats obtenus. Nous exposons notamment les études décrivant le comportement d’interfaces UO2/H2O sous faisceau He2+, l’évolution in situ des propriétés des matériaux soumis aux irradiations ou à des recuits haute température, ainsi que la caractérisation d’états excités de matériaux. / The aim of this work is the development of efficient Raman methodologies and equipments, giving access to material properties in extremes conditions. We describe the conception of an original portable Raman, dedicated to in situ measurements, whose versatile headprobe allows material characterization in extremes conditions, offering a large range of excitation wavelengths, and whose optical collection system permits to obtain Raman information in a large number of delicate optical access severe environments. Moreover, the Raman technique is coupled to micro-luminescence measurements (cathodo/iono/photo- luminescence) at the same point of the sample. The device also allows – by the mean of an intensified CCD detector – the Raman and luminescence time resolved characterization, combined to a pulsed ion beam accelerator. This setup gives access to hard reachable informations concerning the sample structure. Finally, this device allows studies of materials in both high temperature and irradiation hostile conditions. Besides, extremes conditions ex situ analysis systems are described in this work. We additionally present the main results obtained in order to validate that the system works and to show its performances. More precisely, we report studies describing the behavior of UO2/H2O interfaces under He2+ particles beam, the in situ evolution of material properties under irradiation or high temperature annealing process, and finally the excited states characterization of materials.

This diploma thesis studies extreme value theory and its application in finan- cial risk management, when focusing on computation of well-known risk measure - Value at Risk (VaR). The first part of the thesis reviews theoretical background. In particular, it rigorously discusses the extreme value theory when emphasi- zing fundamentals theorems and their consequences followed by the summary of methods based on this theory, specifically, Block Maxima method, Hill met- hod and Peaks over Threshold method. Moreover, specific issues that may arise in such applications and ways how to deal with these problems are described. The second part of the thesis contains extensive empirical study, which together with theoretical foundings applies each of the examined method to real market data of the closing prices of Dow Jones Industrial Average stock index, stocks of JPMorgan and stock index Russell 2000 in order to compare methods based on extreme value theory together with the classic methodology RiskMetrics. 1

Ontologies are formal knowledge models that describe concepts and relationships and enable data integration, information search, and reasoning. Ontology Design Patterns (ODPs) are reusable solutions intended to simplify ontology development and support the use of semantic technologies by ontology engineers. ODPs document and package good modelling practices for reuse, ideally enabling inexperienced ontologists to construct high-quality ontologies. Although ODPs are already used for development, there are still remaining challenges that have not been addressed in the literature. These research gaps include a lack of knowledge about (1) which ODP features are important for ontology engineering, (2) less experienced developers' preferences and barriers for employing ODP tooling, and (3) the suitability of the eXtreme Design (XD) ODP usage methodology in non-academic contexts. This dissertation aims to close these gaps by combining quantitative and qualitative methods, primarily based on five ontology engineering projects involving inexperienced ontologists. A series of ontology engineering workshops and surveys provided data about developer preferences regarding ODP features, ODP usage methodology, and ODP tooling needs. Other data sources are ontologies and ODPs published on the web, which have been studied in detail. To evaluate tooling improvements, experimental approaches provide data from comparison of new tools and techniques against established alternatives. The analysis of the gathered data resulted in a set of measurable quality indicators that cover aspects of ODP documentation, formal representation or axiomatisation, and usage by ontologists. These indicators highlight quality trade-offs: for instance, between ODP Learnability and Reusability, or between Functional Suitability and Performance Efficiency. Furthermore, the results demonstrate a need for ODP tools that support three novel property specialisation strategies, and highlight the preference of inexperienced developers for template-based ODP instantiation---neither of which are supported in prior tooling. The studies also resulted in improvements to ODP search engines based on ODP-specific attributes. Finally, the analysis shows that XD should include guidance for the developer roles and responsibilities in ontology engineering projects, suggestions on how to reuse existing ontology resources, and approaches for adapting XD to project-specific contexts.

Worsening climate changes effects are predicted to increase the severity and frequency of extreme weather events (EWE), which can disrupt food systems, from the local to global level, and compromise community food security. In the rural U.S., food insecurity, poverty, low economic growth, and population loss are prevalent, and rural communities often lack the physical capital to bolster community resiliency to climate change adaptation. In 2011, Tropical Storm Irene (TS Irene) in Vermont was the most damaging EWE the state’s history. Severely damaged roads, infrastructure, homes, and land, rendered many rural towns isolated for up to several days. The levels and types of social capital (bridging and/or bonding) affect social cohesion, which in turn influences how the community responds to an EWE. Rural Vermont communities isolated by TS Irene had to respond to a disruption of basic needs, including food security, without the ability to depend on outside resources. We investigate how social capital influenced these community responses to TS Irene, and how the community actions affected community food security. To better understand how social capital influences community response to food insecurity following an EWE, we created a social capital framework on food security. We then conducted thirty-three semi-structured interviews in three Vermont communities known to have been severely affected by TS Irene, and isolated for several days. Using grounded theory, analysis resulted in social capital having a profound influence on community responses to food security following an EWE. Additionally, the type of social capital – bonding and/or bridging – affected both how the community mitigated food insecurity in the short-term, and upheld food security in the weeks following TS Irene. We found that not only do high degrees of social capital affect community response to acute food security needs after an EWE, but also that a community’s sense of place is different depending on the level of community social capital present prior to an EWE. The community response also shaped the community’s perception of, and ability to creating social capital five years after the event. Previous research indicates social capital is important in both community food security and climate shock responses. We discuss the need for rural development and community social capital to build rural resilience and adaptation for future EWE. As such, we suggest that promoting the development of social capital within rural communities through community development - creation of public events, investment in public infrastructure and schools, and the promotion of locally owned and operated businesses - can build resiliency and adaptation to future EWE by promoting the growth of community social capital, both bonding and bridging, within rural communities.

No description available.

Surface gravity waves carry enormous amounts of energy over our oceans, and if their energy could be harvested to generate electricity, it could make a significant contribution to the worlds power demand. But the survivability of wave energy devices in harsh operating conditions has proven challenging, and for wave energy to be a possibility, peak forces during storms and extreme waves must be studied and the devices behaviour understood. Although the wave power industry has benefited from research and development in traditional offshore industries, there are important differences. Traditional offshore structures are designed to minimize power absorption and to have small motion response, while wave power devices are designed to maximize power absorption and to have a high motion response. This increase the difficulty of the already challenging survivability issue. Further, nonlinear effects such as turbulence and overtopping can not be neglected in harsh operating conditions. In contrast to traditional offshore structures, it is also important to correctly account for the power take off system in a wave energy converter (WEC), as it is strongly coupled to the devices behaviour. The focus in this thesis is the wave loads and the peak forces that occur when a WEC with a limited stroke length is operated in waves higher than the maximum stroke length. The studied WEC is developed at Uppsala University, Sweden, and consists of a linear generator at the seabed that is directly driven by a surface buoy. A fully nonlinear CFD model is developed in the finite volume software OpenFOAM, and validated with physical wave tank experiments. It is then used to study the motion and the forces on the WEC in extreme waves; high regular waves and during tsunami events, and how the WECs behaviour is influenced by different generator parameters, such as generator damping, friction and the length of the connection line. Further, physical experiments are performed on full scale linear generators, measuring the total speed dependent damping force that can be expected for different loads. The OpenFOAM model is used to study how the measured generator behaviour affects the force in the connection line.

Extreme ultraviolet (XUV) frequency combs exhibit promise for enabling high-precision spectroscopic measurements of myriad chemical species for the first time. Coherent XUV radiation can be generated through high harmonic generation (HHG) in femtosecond enhancement cavities. HHG efficiency is limited by nonlinear phase shifts induced by residual intracavity plasma. The goal of this work is to gain insight regarding plasma dynamics in order to allay the detrimental effects of plasma interactions. Our approach is to conduct simulations of cavity pump-probe experiments by probing with higher-order transverse modes. We propose methods for estimating spatial plasma profiles, gas jet velocities, and the plasma recombination coefficient based on measurements of plasma-induced phase shifts. Beam distortion due to plasma interaction is analyzed and used as another reference for plasma dynamics.

This thesis discusses the development of a Numerical Wave Tank (NWT) capable of describing the coupled behaviour of Wave Energy Converters (WECs) and their moorings under extreme wave loading. The NWT utilises the open-source Computational Fluid Dynamics (CFD) software OpenFOAM(R) to solve the fully nonlinear, incompressible, Reynolds-Averaged Navier-Stokes (RANS) equations for air and water using the Finite Volume Method (FVM) and a Volume of Fluid (VOF) treatment of the interface. A method for numerically generating extreme waves is devised, based on the dispersively-focused NewWave theory and using the additional toolbox waves2Foam. A parametric study of the required mesh resolution shows that steeper waves require finer grids for mesh independence. Surface elevation results for wave-only cases closely match those from experiments, although an improved definition of the flow properties is required to generate very steep focused waves. Predictions of extreme wave run-up and pressure on the front of a fixed truncated cylinder compare well with physical measurements; the numerical solution successfully predicts the secondary loading cycle associated with the nonlinear ringing effect and shows a nonlinear relationship between incident crest height and horizontal load. With near perfect agreement during an extreme wave event, the reproduction of the six degree of freedom (6DOF) motion and load in the linearly-elastic mooring of a hemispherical-bottomed buoy significantly improves on similar studies from the literature. Uniquely, this study compares simulations of two existing WEC designs with scale-model tank tests. For the Wavestar machine, a point-absorber constrained to pitch motion only, results show good agreement with physical measurements of pressure, force and float motion in regular waves, although the solution in the wake region requires improvement. Adding bespoke functionality, a point-absorber designed by Seabased AB, consisting of a moored float and Power Take-Off (PTO) with limited stroke length, translator and endstop, is modelled in large regular waves. This represents a level of complexity not previously attempted in CFD and the 6DOF float motion and load in the mooring compare well with experiments. In conclusion, the computational tool developed here is capable of reliably predicting the behaviour of WEC systems during extreme wave events and, with some additional parameterisation, could be used to assess the survivability of WEC systems at full-scale before going to the expense of deployment at sea.

Ontologies are formal knowledge models that describe concepts and relationships and enable data integration, information search, and reasoning. Ontology Design Patterns (ODPs) are reusable solutions intended to simplify ontology development and support the use of semantic technologies by ontology engineers. ODPs document and package good modelling practices for reuse, ideally enabling inexperienced ontologists to construct high-quality ontologies. Although ODPs are already used for development, there are still remaining challenges that have not been addressed in the literature. These research gaps include a lack of knowledge about (1) which ODP features are important for ontology engineering, (2) less experienced developers' preferences and barriers for employing ODP tooling, and (3) the suitability of the eXtreme Design (XD) ODP usage methodology in non-academic contexts. This dissertation aims to close these gaps by combining quantitative and qualitative methods, primarily based on five ontology engineering projects involving inexperienced ontologists. A series of ontology engineering workshops and surveys provided data about developer preferences regarding ODP features, ODP usage methodology, and ODP tooling needs. Other data sources are ontologies and ODPs published on the web, which have been studied in detail. To evaluate tooling improvements, experimental approaches provide data from comparison of new tools and techniques against established alternatives. The analysis of the gathered data resulted in a set of measurable quality indicators that cover aspects of ODP documentation, formal representation or axiomatisation, and usage by ontologists. These indicators highlight quality trade-offs: for instance, between ODP Learnability and Reusability, or between Functional Suitability and Performance Efficiency. Furthermore, the results demonstrate a need for ODP tools that support three novel property specialisation strategies, and highlight the preference of inexperienced developers for template-based ODP instantiation---neither of which are supported in prior tooling. The studies also resulted in improvements to ODP search engines based on ODP-specific attributes. Finally, the analysis shows that XD should include guidance for the developer roles and responsibilities in ontology engineering projects, suggestions on how to reuse existing ontology resources, and approaches for adapting XD to project-specific contexts.

This thesis examines collective identity construction within the extreme right movement Alt-Right that gained public recognition during the 2016 US presidential campaign. Despite it being an increasingly stigmatized practice to openly articulate racist ideas in contemporary society, the Alt-Right movement managed to gain a following by doing just that. As collective identity funds collective action, a discourse analysis in line with Ernesto Laclau and Chantal Mouffe’s strand of discourse theory was conducted to understand what encourages and facilitates participation in the movement’s activities. The material consisted of articles connected to three different factions of the Alt-Right published online and the subsequent comments generated by these. The findings indicate that the collective identity constructed in the Alt-Right is white, masculine and heterosexual. This identity is constructed and reified through contrasting themselves against racialized and gendered Others. It is also reinforced by signs of intelligence, enlightenment, bravery and a sense of rebelliousness and fun linked to the collective identity. The Others are primarily constructed as the Jewish community, non-white groups, women and the LGBTQ community. The use of new information and communications technology facilitated the construction, in allowing participants to create virtual communities online where the collective identity was constructed and reified.