Ce travail de thèse a eu pour but de développer des nouvelles sources lasers, oscillateurs et ampli?cateurs, construites autour des ?bres dopées aux ions ytterbium. Ces systèmes lasers génèrent des fortes puissances moyennes. L’oscillateur réalisé délivre des impulsions courtes (<10 ns) avec des énergies de l’ordre du milliJoule. Le système fonctionne à des cadences variables (10-100 kHz) avec un faisceau polarisé, monomode dont la largeur spectrale est inférieure à 0.1 nm. A?n d’avoir de plus fortes puissances crêtes et des impulsions courtes, deux types d’ampli?- cateurs ont été étudiés. Les résultats expérimentaux que nous avons obtenus sont en accord avec le modèle numérique développé. Le premier système ampli?e un microlaser émettant à 1064 nm dans une ?bre dopée ytterbium. Des puissances crêtes supérieures à 500 kW ont été obtenues avec des impulsions de l’ordre de la nanoseconde et une cadence comprise entre 1 kHz et 30 kHz. Le second ampli?cateur est construit autour d’un oscillateur à ?bre dopée ytterbium déclenché injecté dans une deuxième ?bre qui constitue l’ampli?cateur. L’originalité de ce système réside dans le cou- plage de deux cavités. Nous avons alors en sortie deux faisceaux cohérents, polarisés, monomode, indépendamment ajustables en énergie. En?n, nous avons utilisé les sources lasers développées, qui présentent des caractéristiques spec- trales, modales, énergétiques adéquats pour effectuer la conversion de fréquence. Des ef?cacités de l’ordre de 64 % et 38 % ont été atteintes respectivement en doublage et en triplage. Les faisceaux en sortie de ces systèmes possèdent des remarquables caractéristiques spatiales et temporelles. / This work presents the development of oscillators and ampli?ers build around new ytterbium rod type ?ber. These ?ber systems generate high average power generation. The oscillator makes it possible to deliver well linearly polarized, almost TEM 00 mode, and millijoule-level nanosecond pulses at a tunable repetition rate (10-100 kHz). The spectral bandwidth was shown to be less than 0.1 nm. To achieve higher peak power and shorter pulses, two types of ampli?ers have been developed and characterized. The experimental results we obtain, do well agree with the numerical simulations we developped. The ?rst system ampli?es in a rod type ?ber the nanosecond pulses yielded by a microlaser working at 1064 nm wavelength injected . Its provides pulses with a high peak power system (500 kW). Its repetition rate was tuned from 1 kHz to 30 kHz. The second ampli?er was built using a Q-switched ytterbium doped ?ber oscillator injected in a second ?ber which acts as ampli?er. In this original system the two cavities are coupled. It delivers two nanosecond pulses that are coherent, polarized, almost TEM00 single mode beams and that can have independently tunable pulse energies. We have shown that these oscillators and ampli?ers can be easily doubled and tripled in fre- quency. Very high ef?ciency of about 64 % and 38 % have been achieved respectively at 2? and 3?. These outputs have been to have remarquable spatial and temporal characteristics.

Made available in DSpace on 2014-12-17T14:33:08Z (GMT). No. of bitstreams: 1 LeideAPS_DISSERT.pdf: 986741 bytes, checksum: e18d4b42b9411720a51bd3f7786fa126 (MD5) Previous issue date: 2012-09-25 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Cyanobacterial blooms are common in eutrophic reservoirs in Brazilian northeastern semi-arid. Given this reality, the present study aimed to analyze the effect of potentially toxic cyanobacterial blooms in Gargalheiras reservoir (semi-arid) on the cladocerans Ceriodaphnia dubia and Daphnia gessneri. In vitro chronic bioassays were performed with reservoir water dilutions from August/2011 to May/2012 and the following effects were evaluated on: intrinsic rate of population growth (r), reproductive parameters (age of first reproduction and fecundity per capita) and cladocerans movements. Phytoplankton was dominated by Cylindrospermopsis raciborskii and Planktothrix agardhii and saxitoxin and microcystin were detected in reservoir water. In most months C. dubia showed differences in r between control (absence of cyanobacteria) and treatments, and has shown negative effects on reproductive parameters. In all months paralysis of swimming movements was observed in C. dubia when both C. raciborskii and saxitoxin (cyanotoxin neurotoxic) were present in water. While C. dubia was sensitive to the reservoir water containing cyanobacteria, D. gessneri showed less intense negative effects in r and reproductive parameters. Furthermore, D. gessneri showed no paralysis of swimming movements. These results support the hypothesis in the literature that D. gessneri is resistant to the Cylindrospermopsis effects. The clone&#8223;s life history may be a key to understand the results. The C. dubia clone, isolated from eutrophicated environment, is in the lab for ten years and it is an exotic species in Brazil. D. gessneri is a common species in the country and this clone was isolated from the Gargalheiras reservoir (where there are constant blooms of potentially toxic cyanobacteria) a year ago. Perhaps the recent contact with cyanobacteria explain the higher resistance presented by this D. gessneri clone. In conclusion, the cladocerans studied have different levels of sensitivity to cyanobacteria, characterizing species-specific responses / Flora??es de cianobact?ras s?o frequentes em reservat?rios eutr?ficos do semi-?rido do nordeste brasileiro. Diante dessa realidade o presente trabalho objetivou analisar o efeito de flora??es de cianobact?rias potencialmente t?xicas do reservat?rio Gargalheiras (semi-?rido brasileiro) sobre os clad?ceros Ceriodaphnia dubia e Daphnia gessneri. Foram realizados ensaios cr?nicos in vitro com dilui??es de ?gua do reservat?rio de agosto/2011 a maio/2012 e foram avaliados efeitos sobre: taxa intr?nseca de crescimento populacional (r), par?metros reprodutivos (idade da primeira reprodu??o e fecundidade per capita) e movimenta??o dos clad?ceros. O fitopl?ncton foi dominado por Cylindrospermopsis raciborskii e Planktothrix agardhii e houve detec??o de saxitoxina e microcistina na ?gua do reservat?rio. Na maioria dos meses C. dubia apresentou diferen?a em r entre controle (aus?ncia de cianobact?rias) e tratamentos, al?m de ter apresentado efeitos negativos nos par?metros reprodutivos. Observou-se ainda um efeito de paralisia dos movimentos natat?rios de C. dubia em todos os meses, concomitante ? presen?a de C. raciborskii e saxitoxina (cianotoxina neurot?xica) na ?gua. Enquanto C. dubia apresentou-se sens?vel ? ?gua do reservat?rio contendo cianobact?rias, D. gessneri apresentou efeitos negativos menos intensos em r e nos par?metros reprodutivos. Al?m disso, esta esp?cie n?o teve os movimentos paralisados. Esses resultados apoiam a hip?tese levantada na literatura de que D. gessneri apresenta resist?ncia aos efeitos da Cylindrospermopsis. A hist?ria de vida dos clones pode ser uma chave para compreens?o dos resultados. O clone de C. dubia, isolado de ambiente eutrofizado, est? em laborat?rio h? dez anos e essa ? uma esp?cie ex?tica no Brasil. D. gessneri ? uma esp?cie comum no pa?s e este clone foi isolado h? um ano do reservat?rio Gargalheiras, onde h? constantes flora??es de cianobact?rias potencialmente t?xicas. A hip?tese mais prov?vel ? que o contato recente deste clone de D. gessneri com cianobact?rias tenha lhe conferido maior resist?ncia. Conclui-se que os clad?ceros estudados apresentam diferentes n?veis de sensibilidade ?s cianobact?rias, caracterizando respostas esp?cie-espec?ficas

Les lasers à fibre de haute puissance constituent depuis une dizaine d’année un outil pertinent pour un nombre croissant d’applications. Dans le cadre d’un contrat CIFRE entre la société Eolite Systems et le laboratoire Xlim (UMR 7252 du CNRS et de l’Université de Limoges), mon projet de thèse a consisté à développer les briques technologiques de futures sources lasers / High-power fiber lasers adress an increasing number of applications since ten years. In the frame of a CIFRE contract between the company Eolite Systems and Xlim (joint laboratory between CNRS and the University of Limoges), the goal of this PhD project was to develop the technological blocs to achieve all-fibre high-power lasers emiting out of the conventional spectral band covered by existing lasers.Modal instabilities in large mode area (LMA) fibers are currently the main limitation of the fiber lasers power scaling. We have experimentally demonstrated the relevance of inner cladding aperiodic structures to efficiently delocalize higher order modes outside the gain region. A systematic study of passive fibers based on such structures has shown the single propagation of the fundamental mode over a wide wavelength range from 1 to 2 µm for dimension of core up to 85 µm. This effective mode delocalization even extends up to a core dimension of 140 µm at a 2 µm wavelength.The combination of high power picosecond fiber laser with an average power of 22.7 W and a hydrogen-filled inhibited coupling Kagome fiber allowed us to generate two Raman combs over five frequency octaves from 321 nm to 12.5 µm. These two combs are controlled by the laser pump polarization and generated an average power of 10.1 W displayed over 70 laser lines for circular pump polarization and 8.6 W over 30 lines for linear polarization. Some laser lines within these combs have been generated for the first time from high-power fiber source in the mid-infrared range. We have also demonstrated the generation of high-power line by optimizing the first vibrational Stokes at 1.8 µm with an average power of 9.3 W and a quantum efficiency of the frequency conversion stage close to 80%.

This diploma thesis solves the construction and technological preparation of the production hall with administration building for company Mont-Tech localized in Brno. The following documents are processed for the project. These are: technical report, coordination situation with wider transport route relationships, time and financial plan for construction, study of the implementation of the main technological stages, design of site facilities, proposal of the main building machines and mechanisms, technological regulations and related control and testing plans. In addition were prepared – the itemized budget of the main buildings, the plan of safety and health protection and construction details.

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Tantrische Praktiken von Meditation in Zurückgezogenheit sind auf der tibetischen Hochebene seit mindestens einem Jahrtausend verbreitet, doch ihre äußerst elitäre und geheime Natur hat ihre Erforschung bisher verhindert. Diese Dissertation definiert die vormoderne Struktur der eremitischen Tradition in Khams, die von der Ris med-Bewegung festgelegt wurde, und widmet sich der Wiederbelebung dieser Tradition im modernen Khams unter der chinesisch-kommunistischen Herrschaft. Die Fallstudie bildet die ’Ba’ rom bKa’ brgyud- "Meditationsschule von La phyi" (La phyi sgom grwa) mit Fokus auf den gTum mo-Verwirklicher Tshul khrims mthar phyin (geb. 1947), der als zeitgenössische Verkörperung des Mi la ras pa gilt. Gemäß der Dissertation liegt die rituelle und soziale Macht des tibetischen Eremiten in der Ausführung, Verkörperung und Aussöhnung von Paradoxa: das Erreichen von soteriologischen Zielen im weltlichen Leben sowie die Lösung der Dilemmas der Tibeter in Krisenzeiten. So wird Entsagung zu einer affirmativen Strategie, die Netzwerke aktiviert, die wiederum Eremiten, ihre Linien, Praktiken und Trainingsstätten seit Jahrhunderten unterstützten. Der Antrieb für soziale Ermächtigung der Einsiedler liegt in der Radikalität ihrer Entsagung, bei der nicht nur erwartet wird, Befreiung und Erleuchtung unvermeidlich zu generieren, sondern diese wie Mi la ras pa "in diesem Leib und Leben" zu verwirklichen. Eine solche wahrgenommene Transformation des Körpers durch Meditation ist entscheidend für die Befähigung der Eremiten, Widersprüche zu versöhnen und Einsiedeleien zu gründen, die als Orte für eine effektive Identitätskonstruktion und Sphären der Autonomie und Macht, die aus der lokale Geschichte und heilige Stätten gewonnen werden, dienen. Gerade in Krisenzeiten neigen Einsiedeleien dazu, Netzwerke zu bilden und zu einer alternativen Bewegung zu werden, die die etablierten Machtstrukturen umgeht oder gegen sie spricht, zugleich aber ihren religiösen Charakter behält. / Tantric practices of meditation in retreat have been prevalent across the Tibetan Plateau since at least a millennium, yet their highly elitist and clandestine nature has hitherto prevented their exploration and analysis. This thesis defines the pre-modern structure of the hermitic tradition in Khams, codified by the nonsectarian Ris med movement, but devotes most attention to the examination of its revival in contemporary Khams under the Chinese communist rule through the case study of the ’Ba’ rom bKa’ brgyud “meditation school of La phyi” (La phyi sgom grwa), centered around the cotton-clad gtum mo-accomplisher Tshul khrims mthar phyin (b. 1947), eulogized as the contemporary embodiment of Mi la ras pa. The main claim of this dissertation is that the ritual and social power of the Tibetan hermit lies in the performance, embodiment and final reconciliation of paradox – generally attaining soteriological goals in mundane life and specifically, resolving the dilemmas of Tibetans during times of perceived crisis. Acts of renunciation become an affirmative strategy, activating networks that have sustained hermits, their lineages, practices, and training venues for centuries. The reason for social empowerment of hermits lies in the radical nature of their training, which by social agreement is not only bound to generate liberation and enlightenment, but is even able to yield fruit “in this very body and life,” in emulation of Mi la ras pa. Such transformation of the body through meditation is crucial to the hermit’s ability to reconcile contradictions and to establish hermitages as venues for effective identity construction and spheres of autonomy and power, extracted from local history and sacred geography. Especially in times of crisis, hermitages tend to form networks and evolve into a movement for counter-culture, which circumvents or speaks against the established power structures of the day, but at the same time, maintains its essentially religious character.