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After a halt of four years, the n TOF spallation neutron facility at CERN has resumed operation in November 2008 with a new spallation target characterized by an improved safety and engineering design, resulting in a more robust overall performance and e cient cooling. The rst measurement during the 2009 run has aimed at the full characterization of the neutron beam. Several detectors, such as calibrated ssion chambers, the n TOF Silicon Monitor, a Mi- croMegas detector with 10B and 235U samples, as well as liquid and solid scintillators have been used in order to characterize the properties of the neutron uence. The spatial pro le of the beam has been studied with a specially designed \X-Y

We report the detection of a $γ$-ray bubble spanning at least 100$\rm deg^2$ in ultra high energy (UHE) up to a few PeV in the direction of the star-forming region Cygnus X, implying the presence Super PeVatron(s) accelerating protons to at least 10 PeV. A log-parabola form with the photon index $Γ(E) = (2.71 \pm 0.02) + (0.11 \pm 0.02) \times \log_{10} (E/10 \ {\rm TeV})$ is found fitting the gamma-ray energy spectrum of the bubble well. UHE sources, `hot spots' correlated with very massive molecular clouds, and a quasi-spherical amorphous $γ$-ray emitter with a sharp central brightening are observed in the bubble. In the core of $\sim 0.5^{\circ}$, spatially associating with a region containing massive OB association (Cygnus OB2) and a microquasar (Cygnus X-3), as well as previously reported multi-TeV sources, an enhanced concentration of UHE $γ$-rays are observed with 2 photons at energies above 1 PeV. The general feature of the bubble, the morphology and the energy spectrum, are reasonably reproduced by the assumption of a particle accelerator in the core, continuously injecting protons into the ambient medium.

Confidentielle jusqu'au 31 décembre 2013Co-encadrement de la thèse : Maroun Nemer; Distillation columns are one of the main methods used for separating the components of the air. Their inconvenient is the high energy consumption. In order to produce the oxygen needed for oxycombustion with low energy costs, a diabatic distillation column for cryogenic air separation is designed and modeled. It consists of a shell and tubes heat exchanger where the tubes constitute a first column operating at low pressure and the shell a second one operating at high pressure. Coupled mass and heat transfers are modeled and the diabatic column simulated. A comparative exergy analysis between three types of distillation columns for cryogenic air separation shows that the exergy efficiency of the diabatic column designed is 23 % higher than that of the conventional double columns. The distribution of the mixtures in the tubes and the shell is a key point in the distillation process in the shell and tubes heat exchanger. The different forms of uneven distribution are studied and solutions are proposed. A pilot is designed in order to validate experimentally the theoretical concept of diabatic distillation of cryogenic air.; Les colonnes de distillation de l'air constituent l'un des procédés principaux de séparation des composants de l'air mais posent le problème des consommations énergétiques élevées. Dans le but de produire les quantités d'oxygène nécessaire pour les procédés d'oxycombustion à faibles coûts énergétiques, une colonne de distillation diabatique pour la séparation de l'air cryogénique est conçue et modélisée. Elle consiste en un échangeur tubes-calandre où les tubes constituent une première colonne opérant à basse pression et la calandre en constitue une deuxième opérant à haute pression. Les transferts de masse et de chaleur couplés sont modélisés et le fonctionnement de la colonne est simulé. Une analyse exergétique comparative entre trois types de colonnes de distillation d'air cryogénique montre que l'efficacité exergétique de la colonne diabatique conçue est 23 % fois plus élevée que celle des colonnes doubles conventionnelles. La distribution des mélanges dans les tubes et dans la calandre est un point clé dans le procédé de distillation dans l'échangeur tubes-calandre. Les différentes formes de mal répartition sont étudiées et des solutions proposées. Une colonne pilote est dimensionnée pour valider expérimentalement le concept théorique de la distillation diabatique de l'air cryogénique.

Abstract A flame shape bifurcation in the liquid-fueled two-stage swirled BIMER combustor is studied using Large Eddy Simulations. This combustor, developed at the EM2C Laboratory to study Lean Premixed Prevaporized (LPP) burners, is composed of a two-stage injection system: a central swirled pilot stage fueled with a pressure-swirl atomizer, to sustain a piloting flame, and an outer swirled stage fed with a multi-point injection, to generate the LPP regime. After ignition in the pilot-only operating condition, a V flame is stabilized near the Inner Shear Layer (ISL). When switching to multipoint-only injection, a flame shape transition is observed and the flame bifurcates into a M-shape. In this work, we identify the mechanisms that lead to this bifurcation, and we show that the transition is driven by a complex coupling between the flame, the chamber acoustics and the ISL vortices. By switching to a multipoint-only injection, the fuel is essentially given to the ISL flame, which is mainly premixed. Because of the increased heat release rate and thanks to positive Rayleigh criterion, the quarter wave mode of the chamber is promoted. The ISL vortices, locked to this mode, increase in size until they are large enough to merge the flame in the CRZ, the radial momentum budget forcing the flow topology to switch to a bubble-like structure. Therefore, these results show that it is the existence of two possible flow topologies that renders this flame shape transition possible, the instability being responsible for transferring sufficient energy to the flow to enable the transitioning and the flame then changing its shape simply to adapt to the new topology.

Abstract The fuzzy control of the super-conducting magnetic energy storage (SMES) is proposed to improve the transient stability and damping requirements of multi-machine power systems. The effects of the SMES control on the line power transfer are considered to design a fuzzy controller. The theoretical realization of the proposed control scheme is presented. The simulation study of the New-England test system is carried out. The practical implementation based on the local measurements is explained. The improvement of the system's critical clearing time and also the system damping requirements are clearly demonstrated Finally a conclusion is provided.

Globally, agriculture is the mainstay of most well planned economies because it contributes significantly to the national GDP, creates employment, provides food for human sustenance, raw materials for industry and earns foreign exchange. Nigeria is blessed with tremendous agricultural resources spanning several agro-ecological zones. Nigeria’s total land area is 92.3 million ha with cultivable area estimated at 84 million ha, which is 91% of the total area. Forests account for 13% of the land area. Most of the country’s land area is fertile and conducive for growing a wide range of crops and raising livestock. Nigeria’s 853 kilometer coastline along the Gulf of Guinea is a gateway to a vast ocean which together with ample fresh water resources provided by the Niger and Benue river systems afford tremendous potential for fisheries and aquaculture/mariculture. Nigeria took advantage of these resources to establish itself as an agricultural powerhouse in the 1960s. According to statistics from the UN Food and Agricultural Organization (FAO), by 1961 the country accounted for 42% of the global trade in groundnut oil, 27% of the world’s palm oil industry and 18% of global trade in cocoa. The country was also self-sufficient in food production before the discovery of oil in the 1960s.