Cette thèse établit un cadre d’évaluation des stress tests financiers, en identifiant leurs principales limites. Trois approches ont été proposées pour améliorer les pratiques actuelles à chaque étape du processus. Elles incluent : (i) un modèle semi-paramétrique TVE–copules-paires pour les facteurs de risque financiers, avec un accent particulier sur les valeurs extrêmes, (ii) un modèle d'évaluation pour estimer l'impact de ces facteurs sur un système financier, via des effets directs, indirects et de contagion, en considérant les réactions endogènes publiques et privées, et (iii) une approche bayésienne pour mener une sélection systématique des scénarios de stress pour des portefeuilles non linéaires. Le modèle de risque a montré de meilleures performances par rapport à la plupart des spécifications courantes ; ce qui augmente la crédibilité du test. Le modèle d'évaluation est estimé pour le système bancaire français, révélant ses principales sources de vulnérabilité et le rôle clé des réactions publiques. Enfin, l'approche bayésienne a permis de remplacer les scénarios subjectifs traditionnels et d’inclure les résultats de stress tests dans la gestion quantitative des risques aux côtés des autres outils conventionnels / This thesis has set a comprehensive framework to assess the relevance of financial stress tests, identifying their main drawbacks. Three robust and flexible model frameworks have been proposed to improve current practices in each of the tests’ stages. This is achieved through: (i) a semi-parametric EVT–Pair-copulas model for financial risk factors, with a specific focus on extreme values, (ii) a valuation model to assess the impact of risk factors on a financial system, through direct and indirect effects, contagion channels, and considering private and public response functions, and (iii) a Bayesian-based approach to run a systematic selection of stress scenarios for nonlinear portfolios. The presented risk model has proven to outperform commonly used specifications, hence increasing the test’s credibility. Estimated for the French banking system, the valuation model revealed the related risk profile and the main vulnerabilities. Public responses turned to be of vital interest. Finally, the Bayesian approach allows replacing the traditional subjective scenarios and including the tests’ results in quantitative risk management alongside with other conventional tools

The diploma thesis deals with stress testing as a specific tool which is used by European Banking Association for banking sector financial stability assessment. The main aim is to provide reader with analysis of EBA stress testing. Both the EBA methodology and 2016 results are analyzed in second part. Due to high costs spend on stress testing process I consider practical usage from the bank point of view as very important. This issue is discussed in fourth part of this thesis.

As part of the global work towards reducing CO2 emissions, all vehicles needs to be electrified, or fueled by green fuels. Batteries have already revolutionised the car market, but fuel cells are believed to be a key energy conversion system to be able to electrify also heavy duty vehicles. The type of fuel cell commercially available for vehicles today is the polymer electrolyte membrane fuel cell (PEMFC), but for it to be able to take a larger market share, the cost must be reduced while sufficient lifetime is ensured. The PEMFC is a system containing several components, made of different materials including the polymer membrane, noble metal catalyst particles, and metallic bipolar plate. The combination of different materials exposed to elevated temperature, high humidity and low pH make the PEMFC components susceptible to corrosion and degradation. The noble metal catalyst is one of the major contributors to the high cost. In this work, the latest research on new catalyst materials for PEMFCs are overviewed. Furthermore, electrodeposition as a simple synthesis route to test different Pt-alloys for the cathode catalyst in the fuel cell is explored by synthesis of PtNi and PtNiMo. The gas diffusion layer of the PEMFC is used as substrate to reduce the number of steps to form the membrane electrode assembly. In addition to cheaper and more durable materials, understanding of how the materials degrade, and how the degradation affects the other components is crucial to ensure a long lifetime. Finding reliable test methods to validate the lifetime of the final system is necessary to make fuel cell a trusted technology for vehicles, with predictable performance. In this work, commercial flow plates are studied, to see the effect of different load cycles and relative humidities on the corrosion of the plate. Defects originating from production is observed, and the effect of these defects on the corrosion is further analysed. Suggestions are given on how the design and production of bipolar plates should be made to reduce the risk of corrosion in the PEMFC. / Som en del av det globala arbetet med at reducera utsläppen av koldioxid måste alla fordon elektrifieras eller tankas med förnybart bränsle. Batterier har redan revolutionerat bilmarknaden, men bränsleceller är en viktig pusselbit för att också elektrifiera tunga fordon. Den typen av bränsleceller för fordon som finns tillgänglig på den kommersiella marknaden i dag är polymerelektrolytbränslecellen (PEMFC). För att PEMFC skall ta en större marknadsandel måste kostnaderna minskas och livslängden förlängas. PEMFC består av ett antal komponenter gjorda av olika material, bland annat polymer membran, ädelmetallkatalysator, och metalliska bipolära plattor. Kombinationen av olika material i tillägg till den höga temperaturen, hög fuktighet och låg pH gör att materialen i bränslecellen är utsatta för korrosion. Ädelmetallkatalysatorn är en av de kostdrivande komponenterna i bränslecellen. I denna studien presenteras en översikt över framstegen inom katalysatormaterial för PEM bränsleceller de senaste två åren. Sedan studeras elektroplätering som en enkel produktionsmetod för nanopartiklar av platina legeringar. Möjligheten att simultant plätera fler metaller, och att använda gasdiffutions-skiktet från bränslecellen som substrat för att reducera antal produktionsteg och därmed reducera kostnader, undersöks. Det möjliggör också snabb testning av olika legeringar för att identifiera den optimala sammansättningen med hög prestanda, lång livslängd och lite platina. I tillägg till att ta fram billigare och tåliga material är det viktigt att förstå hur materialen degraderar och hur degraderingen av ett material påverkar de andra komponenterna. Med den kunskapen kan man utveckla accelererade testmetoder för att bedöma livslängden av hela bränslecellen. Validerade testmetoder är viktigt för att styrka förtroendet till nya teknologier. I denna studien fokuseras det också på korrosion av bipolära plattor, och hur olika lastcykler och fuktnivåer som kan bli applicerad vid accelererad testning påverkar korrosionen. Också effekten av defekter från tillverkningen i den skyddande beläggningen analyseras med hänsyn till korrosion, för att ge mer insikt i hur bipolära plattor kan designas och produceras för att minska korrosionen.

Panic Disorder (PD) has been associated with abnormalities in the respiratory system for a long time, and treatment programs aimed at reversing these abnormalities have been developed. Panicogenic effects of biological challenges have been shown to be altered after successful treatment. Furthermore, there is evidence that anxious non-PD patients show similar responses to these challenges and hence may benefit from some kind of breathing training (BT). To test these assumptions, we recruited 45 PD patients, 39 Episodic Anxiety (EA) patients who suffered from subclinical panic attacks, and 20 non-anxious controls (NAC). Patients were randomized to one of two versions of a 4-week therapy with BT, either lower or raise end-tidal pCO2, or a waiting list (WL). Before and after treatment, participants underwent in randomized order a Voluntary Hypoventilation (VHO) test and a Voluntary Hyperventilation (VHT) test in which they were asked to either lower or raise their pCO2 while psychophysiological measures were recorded. Each test consisted of 3 segments: 1 min baseline, 3 min paced breathing, and 8 min recovery. Before treatment, PD and EA patients were more anxious, distressed, tense, and worried than NAC, and felt more dizziness, chest pain, and nausea during the laboratory assessment. However, increases in psychological symptoms or physiological sensations from baseline to the paced breathing segments were not different between groups. The two tests produced similar changes except that anxiety and dizziness increased more during the VHT than VHO. We replicated baseline breathing abnormalities previously reported for PD patients, namely greater respiration rate, tidal volume instability, and number of sighs. However, analyses did not find that patients recovered slower to either challenge. After treatment, both therapies improved on the main outcome measure. Furthermore, BT affected baseline pCO2, resulting in lower levels in the hypocapnic groups and higher levels in the hypercapnic groups without affecting any other measures. We conclude that baseline respiratory abnormalities are specific to PD. However, data suggest that the manipulations might have been too weak to elicit other previously reported group differences. Breathing training was equally effective for the lower and raise BT. Hence, factors unrelated to modifying one’s pCO2 must have accounted for the symptomatic improvement. Breathing training should not be restricted to PD but be applied to all patients suffering from anxiety attacks.

In the first part of this thesis, we introduce a new methodology for stress-test exercises. Our approach allows to consider richer stress-test exercises, which assess the impact of a modification of the whole distribution of asset prices' factors, rather than focusing as the common practices on a single realization of these factors, and take into account the potential reaction to the shock of the portfolio manager. The second part of the thesis is devoted to the pricing of bonds with very long-term time-to-maturity (more than ten years). Modeling the volatility of very long-term rates is a challenge, due to the constraints put by no-arbitrage assumption. As a consequence, most of the no-arbitrage term structure models assume a constant limiting rate (of infinite maturity). The second chapter investigates the compatibility of the so-called "level" factor, whose variations have a uniform impact on the modeled yield curve, with the no-arbitrage assumptions. We introduce in the third chapter a new class of arbitrage-free term structure factor models, which allows the limiting rate to be stochastic, and present its empirical properties on a dataset of US T-Bonds.

Electrical connectors are the blocks that connect solar panels together. Whenever a photovoltaic plant commences, the main discussion goes around on solar panels, inverters, charge controllers, etc. But the topic of connectors is usually hardly discussed. Connectors in a photovoltaic system can definitely contribute to improve the overall performance of the system, provided that importance is given while selecting the connectors. The electrical connectors used in photovoltaic systems can be connected in two possible ways. Connectors can be connected either in a pure-connection or in a cross-connection. Male and female connectors from the same brand results a pure-connection (P-C). Male and female connectors from two different brands results in a cross-connection (C-C). There have been discussions in photovoltaic, electrical connector markets and international solar events regarding the risks involved, losses and consequences due to a cross-connection. The main reason behind cross-connections is the unawareness of the installers in knowing the difference between a pure-connection and a cross-connection. Even though the installers are aware of this difference, they are not aware of the consequences of cross-connections. Multi-Contact, a leading electrical connector manufacturer of MC4 photovoltaic connectors affected by the counterfeit products of MC4, due to the sudden boom in the solar market during 2011-12. With the help of TÜV Rheinland, Multi-Contact conducted couple of tests namely temperature increase test and accelerated stress tests to understand the disadvantages of cross-connections. This thesis tried to replicate the tests performed by Multi-Contact in an attempt to understand the test results by using connectors that are used in the Swedish market. Performing temperature increase test and accelerated stress tests on most commonly used connectors in the Swedish market is the main aim of this thesis. The first test, gives an understanding of the temperature variations across various connector sets (four connector sets from various manufacturers used in this thesis) and the latter tests helps to understand the quality of the contact resistance of these connector sets. The four connector set manufacturers used in this test were Multi-Contact (MC), Weidmüller (WM), Blussun solar (BSS) and PBM. The quality of contact resistance of a connector is directly related to the quality of the connector set. During the 20 minutes of the temperature increase test, the connector set from WM performed better than its competitors in the P-C. Whereas, the MC-BSS connector set had performed well in the C-C. The connector type of male MC and female BSS showed its dominance throughout the test. Unfortunately, no conclusions were able to be drawn from this test results due to insufficient information about the test procedure. From the results of accelerated stress tests, the C-C set from MC outperformed its P-C counterpart. All ten connector sets used in this project passed the standard and qualified as connectors with good quality contact resistance. Therefore the best results out of only a P-C connector set does not seems to be completely true. With the standard used in this thesis, it is quite difficult to judge the quality of connectors. Rather than saying a P-C is superior and a C-C is inferior in terms of quality, there is a need to come up with a new method to evaluate the quality of connectors. Matching the connectors based on their tolerances could be a potential solution to the mismatching problem in connectors.

La première partie de cette thèse introduit une nouvelle méthodologie pour la réalisation d’exercices de stress-tests. Notre approche permet de considérer des scénarios de stress beaucoup plus riches qu’en pratique, qui évaluent l’impact d’une modification de la distribution statistique des facteurs influençant les prix d’actifs, pas uniquement les conséquences d’une réalisation particulière de ces facteurs, et prennent en compte la réaction du gestionnaire de portefeuille au choc. La deuxième partie de la thèse est consacrée à la valorisation des obligations à maturité très longues (supérieure à 10 ans). La modélisation de la volatilité des taux de très long terme est un défi, notamment du fait des contraintes posées par l’absence d’opportunités d’arbitrage, et la plupart des modèles de taux d’intérêt en absence d’opportunités d’arbitrage impliquent un taux limite (de maturité infinie) constant. Le deuxième chapitre étudie la compatibilité du facteur "niveau", dont les variations ont un impact uniforme sur l’ensemble des taux modélisés, a fortiori les plus longs, avec l’absence d’opportunités d’arbitrage. Nous introduisons dans le troisième chapitre une nouvelle classe de modèle de taux d’intérêt, sans opportunités d’arbitrage, où le taux limite est stochastique, dont nous présentons les propriétés empiriques sur une base de données de prix d’obligations du Trésor américain. / In the first part of this thesis, we introduce a new methodology for stress-test exercises. Our approach allows to consider richer stress-test exercises, which assess the impact of a modification of the whole distribution of asset prices’ factors, rather than focusing as the common practices on a single realization of these factors, and take into account the potential reaction to the shock of the portfolio manager.
 The second part of the thesis is devoted to the pricing of bonds with very long-term time-to-maturity (more than ten years). Modeling the volatility of very long-term rates is a challenge, due to the constraints put by no-arbitrage assumption. As a consequence, most of the no-arbitrage term structure models assume a constant limiting rate (of infinite maturity). The second chapter investigates the compatibility of the so-called "level" factor, whose variations have a uniform impact on the modeled yield curve, with the no-arbitrage assumptions. We introduce in the third chapter a new class of arbitrage-free term structure factor models, which allows the limiting rate to be stochastic, and present its empirical properties on a dataset of US T-Bonds.