CARACTERISATION EXPERIMENTALE ET MODELISATION DE L’INCIDENCE DES ECOULEMENTS PULSES SUR LE COMPORTEMENT D’UNE TURBINE DE SURALIMENTATION AUTOMOBILE

The downsizing method consisting in the increase of the charge level, often performed by a turbocharger,implies to optimize the energy recovery from exhaust gas through the turbine. In this context, the literaturereview was focused on two axes of research: experimental characterization and the performance modelingmethods of turbines operating under pulsating flow conditions.Subsequently, two literature models were selected and analyzed. A specific power model has beenintegrated into each of them. Then, a quantitative study, a qualitative study and an acoustic study, weredeveloped to evaluate the instantaneous performances, average, and acoustic, of a turbine operating inunsteady conditions.To explore the different ways of turbines modeling improvements, operating under pulsed flowconditions, three new models were tested. These models use an extrapolation method of characteristics fieldsvalues, and use a direct interpolation of these fields. Similarly as for literature models, a quantitative, aqualitative and an acoustics studies were conducted to compare the performances and contribution of eachtype of modeling.Finally, experiments on test bench were performed for different geometries and different turbineoperating conditions. A method able to predict the unsteady turbine efficiency has been proposed. Inaddition, a study about the turbine's acoustic characterization has been completed.La technique du downsizing, passant par l’augmentation du taux de suralimentation, réalisée le plus souvent par un turbocompresseur implique l’optimisation de la récupération de l’énergie des gaz d’échappement par la turbine. Dans ce cadre, une étude bibliographique a été orientée sur deux axes de recherche : la caractérisation expérimentale et les méthodes de modélisation des performances des turbomachines fonctionnant dans des conditions d’écoulement pulsé. Par la suite, deux modèles bibliographique ont été sélectionnés et analysés. Un modèle de puissancespécifique a été intégré à chacun de ces modèles. Ensuite, une étude quantitative, une étude qualitative et une étude acoustique, ont été développées, permettant d’évaluer les performances instantanées, moyennes, et acoustiques d’une turbine fonctionnant en régime instationnaire.Afin de prospecter les différentes voies d’améliorations des modélisations des turbines fonctionnant en écoulement pulsé, trois nouveaux modèles ont été testés. Ces modèles font appel à une méthode d’extrapolation des champs des valeurs caractéristiques et utilisent une interpolation directe de ces champs. De même que pour les modèles issus de la littérature, des études quantitatives, qualitatives et acoustiques ont été menées dans le but de comparer les performances et l’apport de chaque type de modélisation.Enfin, des expérimentations sur banc d’essais ont été réalisées pour différentes géométries de turbines et pour différentes conditions de fonctionnement. Une méthode permettant le calcul du rendement instationnaire de la turbine a été proposée. De plus, une étude portant sur la caractérisation acoustique de la turbine a été effectuée

‘La vida es sueño’ leída desde el desenlace

Estudio las estructuras dramáticas de ‘La vida es sueño’ y en particular de la mal llamada intriga secundaria construida en torno al personaje de Rosaura. La presencia de motivos propios de la comedia de enredo en esta tragedia, y la semejanza del sistema dramático con el que a menudo se encuentra en la comedia de burlador se explica merced a una lectura hacia atrás, es decir a partir del desenlace. El casamiento entre Segismundo y Estrella, lejos de ser un accidente o una convención propia de los finales felices, se considera aquí como el elemento fundamental de la inventio calderoniana, al que necesariamente tienen que llevar las distintas partes de la acción, y así se explica la función y la trayectoria de Rosaura / The present work studies the dramatic structures of La vida es sueño, focusing on the inaptly called «secondary intrigue» constructed around the character of Rosaura.The presence of motives typical of the comedy of intrigue within this tragedy, moreover the fact that the dramatic system is similar to the system quite often found in the «comedia de burlador», can be explained by a lecture directed backwards, that is to say, beginning from the ending.The marriage of Segismundo and Estrella, which is far from being a coincidence or a convention typical of a happy ending, is considered a fundamental element of the Calderonean inventio to which all the different parts of the tragedy necessarily have to lead, and this is how to explain the function and development of Rosaura

Control of near-infrared supercontinuum bandwidth by adjusting pump pulse duration

We experimentally and numerically investigated the impact of input pump pulse duration on the near-infrared bandwidth of supercontinuum generation in a photonic crystal fiber. We continuously stretched the temporal duration of the input pump laser (centered at 1030 nm) pulses from 500 fs up to 10 ps, while keeping fixed the pump peak power. We observed that the long-wavelength edge of the supercontinuum spectrum is increased by 200 nm as the pump pulse duration grows from 500 fs to 10 ps. We provide a quantitative fit of the experimental results by means of numerical simulations. Moreover, we have explained the observed spectral broadening enhancement induced by pump pulse energy by developing an approximate yet fully analytical model for soliton energy exchange through a series of collisions in the presence of stimulated Raman scattering

Spatiotemporal Characterization of Supercontinuum Extending from the Visible to the Mid-Infrared in Multimode Graded-Index Optical Fiber

We experimentally demonstrate that pumping a graded-index multimode fiber with sub-ns pulses from a microchip Nd:YAG laser leads to spectrally flat supercontinuum generation with a uniform bell-shaped spatial beam profile extending from the visible to the mid-infrared at 2500\,nm. We study the development of the supercontinuum along the multimode fiber by the cut-back method, which permits us to analyze the competition between the Kerr-induced geometric parametric instability and stimulated Raman scattering. We also performed a spectrally resolved temporal analysis of the supercontinuum emission.Comment: 5 pages 7 figure

A multiwavelength study of the remnant of nova GK Persei

We present new observations of the nebular remnant of the old nova GK Persei 1901, in the optical using the 2m HCT and at low radio frequencies using the GMRT. The evolution of the nova remnant indicates shock interaction with the ambient medium, especially in the southwest quadrant. Application of a simple model for the shock and its evolution to determine the time dependence of the radius of the shell in the southwest quadrant indicates that the shell is now expanding into an ambient medium that has a lower density compared to the density of the ambient medium ahead of the shock in 1987.There are indications of a recent interaction of the nova remnant with the ambient medium in the northeast quadrant also. The nova remnant of GK Per is detected at all the observed radio frequencies and is of similar extent as the optical remnant. Putting together our radio observations with VLA archival data on GK Per from 1997, we obtain three interesting results: 1. The spectrum above 1.4 GHz follows a power law with an index -0.7 and below 1.4 GHz follows a power law with an index ~ -0.85. This could be due to the presence of at least two populations of electrons dominating the global emission at different frequencies. 2. We record an annual secular decrease of 2.1% in the flux density of the nova remnant at 1.4 and 4.9 GHz between 1984 and 1997 which has left the spectral index unchanged at -0.7. No such decrease is observed in the flux densities below 1 GHz. 3. We record an increase in the flux density at 0.33 GHz compared to the previous estimate in 1987. We conclude that the remnant of nova GK Per is similar to supernova remnants and in particular, to the young supernova remnant Cas A.Comment: 10 pages; uses A&A style; figures 1, 2 & 6 are in JPEG format. Accepted for publication in Astronomy & Astrophysics. Full paper including Figures 1, 2 & 6 may be downloaded from http://www.iiap.res.in/personnel/gca/gca.htm

Obstacles, levers and impacts of organic farming development in Camargue

We are presenting an analysis of the obstacles and levers for the development of organic cropping systems in Camargue, documented with a multicriteria analysis of scenarios of organic farming (OF) development. This communication is built using results from on-farm agronomic monitoring, stakeholders and farmers’ interviews and the use of models for integrated assessment of scenarios. At the farm level, the obstacles are related to identification of profitable cropping systems and rotations that include enough rice, conversion being therefore risky as impacting financial management and requiring a labour reorganisation. At the regional level, the constraints are related to the absence of advisory services for technical issues, and to the lack of coordination among the different stakeholders, to the low incentive of the public policies to convert, and to a relatively opaque organization of the supply chains. At the regional level, we analysed the consequences of two scenarios related to OF development on criteria such as the rice surface area, the quantity and quality of water, energy consumption or the employment generated. These results are expected to contribute to the definition of an action plan about OF development by the local stakeholders

Разработка иммуноферментной тест-системы для анализа иммуногенности вакцины против вирусного гепатита А

Разработка качественного непрямого метода иммуноферментного анализа для выявления титра антител, специфичных к вирусу гепатита А, у вакцинированных мышейDevelopment of a qualitative indirect method of enzyme immunoassay for detecting the titer of antibodies specific to the hepatitis a virus in vaccinated mic

Ge-Doped microstructured multicorefiber for customizable supercontinuum generation

Supercontinuum generation in a multicore fiber in which several uncoupled cores were doped with dissimilar concentrations of germanium was studied experimentally. Germanium doping provided control over the separation between the zero-dispersion wavelength and the 1064-nm wavelength of a Q-switched Nd:YAG pump laser. Supercontinua generated independently in each core of the same piece of fiber displayed clear and repeatable differences due to the influence of germanium doping on refractive index and four-wave mixing. The spectral evolution of the subnanosecond pump pulses injected into the different cores was accurately reproduced by numerical simulations

Dioxin-like, non-dioxin like PCB and PCDD/F contamination in European eel (Anguilla anguilla) from the Loire estuarine continuum: spatial and biological variabilities

To characterize the eel contamination by dioxin-like (dl) and non dioxin-like (ndl) PCBs and PCDD/Fs, 62 eels from the Loire estuary (France) were analyzed. PCB contamination significantly increased from glass eel stage (3.7 ±1.9 and 15.2±4.2 ng.g-1 dw) to other life stages (for yellow eels: 62.8±34.4 and 381.8±181.8 ng.g-1 dw; for silver eels: 93.7±56.3 and 463.2±244.6 ng.g-1 dw respectively for dl and ndl PCB). An inter-site variability based on PCB levels and fingerprints was observed between the three studied sites. The glass eel pattern was mainly characterized by the less chlorinated PCBs contrarily to the other eels, underlying a different bioaccumulation pathway. Overall, eels from this estuary showed an intermediate contamination level compared to other international/national areas. However, more than 60% of studied silver eels displayed WHO2005 PCDD/F and dl-PCB TEQ values higher than the recommended level of 10 pg.g-1 ww. This statement indicates a potential exposure to PCBs through eel consumption, especially with silver individuals, and could potentially lead to damages for the eel population