The emergence of wide-bandgap-based (WBG) devices, such as silicon carbide (SiC) and gallium nitride (GaN), have unveiled unprecedented opportunities, enabling the realization of superior power conversion systems. Among the potential areas of advancement are medium-voltage (MV) and high-voltage (HV) applications, due to the growing demand for high-power-density and high-efficiency power electronics converters. These advancements have propelled a wide adoption of electric vehicles (EV), which in the future will require great improvements in the charging time of these vehicles. Thereby, this thesis attempts to address such a challenge and bring about technological improvements, enabling faster, more efficient, and more effective ways of charging an electric vehicle through the application of MV 3.3 kV SiC MOSFETs. The current fast-charging solution involves heavy and bulky MV-LV transformers, which add installation complexity for EV charging stations. However, this thesis presents an alternative power-delivery solution utilizing an MV dual-active-bridge (DAB) converter. The proposed architecture is designed to directly interface with the MV grid for high-power, fast-charging capabilities while eliminating the need for an installation of the MV-LV transformer. The MV DAB converter utilizes 3.3 kV SiC MOSFETs to realize the next 800 V EV charging system, along with an extended zero-voltage-switching (ZVS) scheme, in order to provide an efficient charging strategy across a wide range of battery voltage levels. Lastly, a detailed design comparison analysis of an MV Flyback converter, targeted for the auxiliary power supply for the proposed MV EV charging architecture, is presented. / The field of power electronics, which controls and manages the conversion of electrical energy, is an important topic of discussion, as new technologies like electric vehicles (EV) are quickly emerging and disrupting the current status-quo of vehicle-choice. In order to promote timely and extensive adoption of such an enabling EV technology, it is critical to understand the current challenges involving EV charging stations and seek out opportunities to engender future innovations. Indeed, wide-bandgap (WBG) devices, such as silicon carbide (SiC) and gallium nitride (GaN), have unveiled unprecedented opportunities in enabling the realization of superior power conversion systems. Thus, utilizing these WGB devices in EV charging applications can bring about improved design and development of EV fast chargers that are faster-charging, more efficient, and more effective. Hence, this thesis presents an opportunity in EV charging station applications with the utilization of medium-voltage SiC MOSFETs. Because the current fast-charging solution involves a heavy and bulky transformer, it adds installation complexity for EV charging stations. However, this thesis presents an alternative power-delivery solution that could potentially provide an efficient and fast-charging mechanism of EVs while reducing the size of EV chargers. All things considered, this thesis provides in-depth evaluation-studies of medium-voltage 3.3 kV SiC MOSFET-based power converters, targeted for future fast EV charging applications. The development and design of the hardware prototype is presented in this thesis, along with testing and verification of experimental results.

La mort cellulaire programmée, ou MCP, est un processus dynamique où les cellules ont la capacité de déclencher et de contrôler leur propre mort. Elle est essentielle et présente chez tous les organismes multicellulaires. Chez les plantes, la MCP permet le développement optimal (ex : formation du xylème, morphologie des feuilles, etc.) de la plante tout en protégeant contre divers stress biotiques et abiotiques (ex : la sécheresse, la chaleur, les UV, etc.). Malgré les avancées de ces dernières années, peu de gènes impliqués dans la mise en place de la MCP induite par les UV-C ont été identifiés chez les plantes. L'objectif était donc de caractériser ces gènes chez Arabidopsis thaliana. L'un des candidats est le gène BI-1, pour Bax Inhibitor-1. Il code pour un facteur anti-apoptotique de la MCP animale également retrouvé chez Arabidopsis thaliana. BI-1 régule aussi le taux de calcium du réticulum endoplasmique, ainsi que la formation des espèces réactives de l'oxygène (ROS), permettant l'activation de la réponse de la cellule au stress. L'expression de ce gène suite à une exposition aux UV-C est augmentée, faisant de lui un candidat pour la réponse aux UV-C. Une fusion du promoteur du gène AtBI-1 au gène rapporteur de la luciférase (pAtBI-1::luciférase) a été insérée dans le génome d'Arabidopsis. Une plante homozygote pour l'insertion de l'ADN-T, 5PL20E, a été isolée. Cette lignée parentale a été ensuite mutagénéisée, et un crible effectué sur la descendance exposée aux UV-C a permis d'identifier un mutant, 2017, dont l'expression de la luciférase était modifiée. Le premier objectif de ce projet était de caractériser ce mutant et de déterminer le lien potentiel avec la régulation de BI-1. Dans une deuxième partie, nous nous sommes intéressés aux rôles des thiorédoxines (TRX) dans la MCP végétale. Ces protéines sont présentes chez tous les organismes vivants. Elles régulent les activités de beaucoup d'enzymes en réduisant leurs ponts disulfures. Peu représentées chez l'homme (deux gènes), elles ont néanmoins un rôle de protection dans la voie de signalisation de l'apoptose. Par contre, chez Arabidopsis, une vingtaine de gènes codant pour les thiorédoxines sont connus. Suite à un autre crible aux UV-C d'une banque de mutants d'insertion, un nouveau mutant pour lequel l'insertion de l'ADN-T était dans le promoteur du gène codant pour la thiorédoxine f1 (AtTRX f1) a été identifié. Chez Arabidopsis, deux gènes codent pour les TRX f. Ces protéines ont d’abord été étudiées en tant que régulateur d’enzymes du cycle de Calvin. Plus récemment, d’autres fonctions ont été attribuées, surtout à la TRX f1. Nous avons obtenu de simples mutants pour les deux gènes et produit par croisement des doubles mutants, pour étudier l'implication des TRX f dans la MCP végétale induite par les UV-C (ultraviolets de type C), le MV (methyl viologen) et l'ABA (acide abscissique). En parallèle, des surexpresseurs de la TRX f1 ont été analysés pour ces mêmes stress abiotiques. L'objectif était de déterminer s'il y a une redondance de fonction entre les deux gènes, puisque ces deux protéines, de la même sous-famille, sont localisées au niveau des chloroplastes. Suite à une induction de la MCP par l'un des stress abiotiques, les réponses observées chez les simples mutants sont similaires à celles des plantes sauvages. Par contre, les doubles mutants paraissent plus résistants aux divers stress, alors que les surexpresseurs semblent nettement plus sensibles que les plantes sauvages. Enfin, un dernier axe a été développé sur le rôle des TRX f dans le contrôle des voies de synthèse et de dégradation de l'amidon pour l'ensemble des plantes de notre essai. Il s'avère que les surexpresseurs produisent une plus grande quantité d'amidon que les plantes sauvages. À l'opposé, les simples mutants ont moins d'amidon au niveau des différents tissus étudiés que les plantes sauvages, et les doubles mutants n'en présentent quasiment pas. La présence d'une quantité plus importante d'amidon chez les surexpresseurs de TRX f influence la sensibilité de ces plantes aux stress abiotiques. À l'inverse, les doubles mutants sont plus résitants à ces mêmes stress, où cette quantité d'amidon est fortement diminuée pour ces plantes.

This thesis examines the production of Tamil youth in the state of Canada as threats, extremists, radicals, terrorists, and as subjects to be engaged in de-politicized humanitarian discourses of reconciliation and peace. By drawing attention to the exclusion of Tamils from rights in legal proceedings, the positioning of youth protesters as harbingers of a multicultural 'crisis,' and the role of education in securing Canada's response to the MV Sun Sea as a 'humanitarian' project, I argue that the targeting Tamils is not only integral to Sri Lanka's ongoing genocide, but is also crucial to the Canadian state's project of white settler colonialism. In examining the law, media and education as sites of racial management in the 'War on Terror' and its globalized counter-terrorism regime I identify the targeting of Tamil diaspora youth as a necessary racial logic for the legitimacy of the Canadian state in an era of official multiculturalism.

This thesis examines the production of Tamil youth in the state of Canada as threats, extremists, radicals, terrorists, and as subjects to be engaged in de-politicized humanitarian discourses of reconciliation and peace. By drawing attention to the exclusion of Tamils from rights in legal proceedings, the positioning of youth protesters as harbingers of a multicultural 'crisis,' and the role of education in securing Canada's response to the MV Sun Sea as a 'humanitarian' project, I argue that the targeting Tamils is not only integral to Sri Lanka's ongoing genocide, but is also crucial to the Canadian state's project of white settler colonialism. In examining the law, media and education as sites of racial management in the 'War on Terror' and its globalized counter-terrorism regime I identify the targeting of Tamil diaspora youth as a necessary racial logic for the legitimacy of the Canadian state in an era of official multiculturalism.

Recently a powerful electron accelerator, 50 MeV race-track microtron, has been taken into clinical use. This gives the opportunity to treat patients with higher x-ray and electron energies than before. Furthermore, treatments can be performed were the entire fractional dose can be delivered in parts of a second. The relative biological effectiveness (RBE) of high energy photons (up to 50 MV) was studied in vitro and in vivo. Oxygen enhancement ratio (OER) of 50 MV photons and RBE of 50 MeV electrons were investigated in vitro. Single-fraction experiments, in vitro, using V-79 Chinese hamster fibroblasts showed an RBE for 50 MV x-rays of approximately 1.1 at surviving fraction 0.01, with reference to the response to 4 MV x- rays. No significant difference in OER could be demonstrated. Fractionation experiments were carried out to establish the RBE at the clinically relevant dose level, 2 Gy. The RBE calculated for the 2 Gy/fraction experiments was 1.17. The RBEs for 20 MV x-rays and 50 MeV electrons were equal to one. In order to investigate the validity of these results, the jejunal crypt microcolony assay in mice was used to determine the RBE of 50 MV x-rays. The RBE for 50 MV x-rays in this case was estimated to be 1.06 at crypt surviving fraction 0.1. Photonuclear processes are proposed as one possible explanation to the higher RBE for 50 MV x-rays. Several studies of biological response to ionizing radiation of high absorbed dose rates have been performed, often with conflicting results. With the aim of investigating whether a difference in effect between irradiation at high dose rates and at conventional dose rates could be verified, pulsed 50 MeV electrons from a clinical accelerator were used for experiments with ultra high dose rates (mean dose rate: 3.8 x 10^ Gy/s) in comparison to conventional (mean dose rate: 9.6 x 10"^ Gy/s). V-79 cells were irradiated in vitro under both oxic and anoxic conditions. No significant difference in relative biological effectiveness (RBE) or oxygen enhancement ratio (OER) was observed for ultra high dose rates compared to conventional dose rates. A central issue in clinical radiobiological research is the prediction of responses to different radiation qualities. The choice of cell survival and dose response model greatly influences the results. In this context the relationship between theory and model is emphasized. Generally, the interpretations of experimental data are dependent on the model. Cell survival models are systematized with respect to their relations to radiobiological theories of cell kill. The growing knowledge of biological, physical, and chemical mechanisms is reflected in the formulation of new models. This study shows that recent modelling has been more oriented towards the stochastic fluctuations connected to radiation energy deposition. This implies that the traditional cell survival models ought to be complemented by models of stochastic energy deposition processes at the intracellular level. / <p>S. 1-44: sammanfattning, s. 47-130: 5 uppsatser</p> / digitalisering@umu

全球經濟情況變動，壽險公司的資產快速增加，國內投資工具無法滿足壽險公司的投資需求，政府大幅增加了壽險公司的投資範圍，如開放壽險公司海外投資上限，希望能提升壽險公司的資金運用效率。然而金融海嘯過後，壽險公司的投資績效受到打擊，金融資產出現大幅跌價，面臨投資跌價損失、資產減損、投資報酬率下降等情況，投資獲利逐漸下滑，影響了壽險公司的整體營運，經營情況日趨嚴峻。於是近年來，國內壽險公司投資收益佔營收比重逐漸增加，資產配置策略及實務上如何進行資金運用操作，實關係著壽險公司經營穩健度及獲利能力。本論文以一個案人壽公司為例，透過MV模型分析2005年至2011年間，在現行法令限制下，壽險公司投資組合的報酬率與風險之影響為何，且既定風險情況下，分析其投資績效，並探討此壽險公司資產配置是否具效率，又可如何調整配置提升投資報酬率，藉以供作壽險業未來資金運用策略之參考。 / As life insurance company assets rapidly increase and vary with global economical situations, domestic investment means no longer satisfy investing needs of life insurance companies. The Government relaxes investment restrictions, financially and legally, aiming to improve the very investment benefit of life insurance companies. But after the financial tsunami, their investment performance decreased, financial assets declined, unrealized losses on investment and asset impairment occurred, and return on Investment went down. The life insurance company’s overall operating conditions became more and more severe. Thus, the facts that the increasing proportion of domestic life insurance companies’ income on investment, asset allocation policy and practice on how to fund operations, do influence the stability and profitability of life insurance companies. Employing the Markowitz portfolio model, this thesis will analyze the investment benefit of life insurance companies with a specific case of a life insurance company during the period between 2005 and 2011. It reassesses issues below: the relation between capital allocation efficiency and risk of life insurance companies under established risk situations, the efficiency of life insurance companies’ asset allocation, and the rearrangement of asset allocation in order to upgrade capital allocation efficiency. These analyses would provide some reference for life insurance companies’ investing strategies in uses of future funds.

Made available in DSpace on 2016-12-12T20:22:53Z (GMT). No. of bitstreams: 1 Marcelo Pereira da Silva.pdf: 1790996 bytes, checksum: 8b61245ad63935d86a70520f22eae9bc (MD5) Previous issue date: 2015-07-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / With the ever-increasing dependence on computers and networks, many systems are required to be continuously available in order to fulfill their mission. Virtualization technology enables high availability to be offered in a convenient, cost-effective manner: with the encapsulation provided by virtual machines (VMs), entire systems can be replicated transparently in software, obviating the need for expensive fault-tolerant hardware. Remus is a VM replication mechanism for the Xen hypervisor that provides high availability despite crash failures. Replication is performed by checkpointing the VM at fixed intervals. However, there is an antagonism between processing and communication regarding the optimal checkpointing interval: while longer intervals benefit processorintensive applications, shorter intervals favor network-intensive applications. Thus, any chosen interval may not always be suitable for the hosted applications, limiting Remus usage in many scenarios. This work introduces Adaptive Remus, a proposal for adaptive checkpointing in Remus that dynamically adjusts the replication frequency according to the characteristics of running applications. Experimental results indicate that our proposal improves performance for applications that require both processing and communication, without harming applications that use only one type of resource. / Com a dependência cada vez maior de computadores e redes, muitos sistemas precisam estar continuamente disponíveis para cumprir sua missão. A tecnologia de virtualização permite prover alta disponibilidade de forma conveniente e a um custo razoável: com o encapsulamento oferecido pelas máquinas virtuais (MVs), sistemas inteiros podem ser replicados em software, de forma transparente, eliminando a necessidade de hardware tolerante a faltas dispendioso. Remus é um mecanismo de replicação de MVs que fornece alta disponibilidade diante de faltas de parada. A replicação é realizada através de checkpointing, seguindo um intervalo fixo de tempo predeterminado. Todavia, existe um antagonismo entre processamento e comunicação em relação ao intervalo ideal entre checkpoints: enquanto intervalos maiores beneficiam aplicações com processamento intensivo, intervalos menores favorecem as aplicações cujo desempenho é dominado pela rede. Logo, o intervalo utilizado nem sempre é o adequado para as características de uso de recursos da aplicação em execução na MV, limitando a aplicabilidade de Remus em determinados cenários. Este trabalho apresenta Adaptive Remus, uma proposta de checkpointing adaptativo para Remus, que ajusta dinamicamente a frequência de replicação de acordo com as características das aplicações em execução. Os resultados indicam que a proposta obtém um melhor desempenho de aplicações que utilizam tanto recursos de processamento como de comunicação, sem prejudicar aplicações que usam apenas um dos tipos de recursos.

The Master Thesis deals with a proposal of algorithm of a protective function for assymetric faults location in resistance-grounded medium voltage networks with decentralized measurement of instantaneous voltage and current values. The theoretical part describes a single pole fault in the resistance-grounded network including the network analysis using the symmetric component method. Furtherly follows brief reserse of nowadays considered possibilities of faults location in the medium voltage networks. The proposed algorithm which works on the principle of negative sequence changes and change differencies of voltage and current is described by mathematical operations and flowchart, and it is furtherly tested in the PSCAD simulator on the proposed network model. Also the algorithm is tested in the Matlab program using the real data from the local distribution network Pod Palackeho vrchem where the initial pilot implementation is assumed. The last part of the thesis includes also the algorithm sensitivity analysis.

In recent years, 3D camera products and prototypes based on Integral imaging (II) technique have gradually emerged and gained broad attention. II is a method that spatially samples the natural light (light field) of a scene, usually using a microlens array or a camera array and records the light field using a high resolution 2D image sensor. The large amount of data generated by II and the redundancy it contains together lead to the need for an efficient compression scheme. During recent years, the compression of 3D integral images has been widely researched. Nevertheless, there have not been many approaches proposed regarding the compression of integral videos (IVs). The objective of the thesis is to investigate efficient coding methods for integral videos. The integral video frames used are captured by the first consumer used light field camera Lytro. One of the coding methods is to encode the video data directly by an H.265/HEVC encoder. In other coding schemes the integral video is first converted to an array of sub-videos with different view perspectives. The sub-videos are then encoded either independently or following a specific reference picture pattern which uses a MVHEVC encoder. In this way the redundancy between the multi-view videos is utilized instead of the original elemental images. Moreover, by varying the pattern of the subvideo input array and the number of inter-layer reference pictures, the coding performance can be further improved. Considering the intrinsic properties of the input video sequences, a QP-per-layer scheme is also proposed in this thesis. Though more studies would be required regarding time and complexity constraints for real-time applications as well as dramatic increase of number of views, the methods proposed inthis thesis prove to be an efficient compression for integral videos.

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