Doctor of Philosophy

dissertationThe Direct Quadrature Method of Moments (DQMOM) was implemented in the Large Eddy Simulation (LES) tool ARCHES to model coal particles. LES coupled with DQMOM was first applied to nonreacting particle-laden turbulent jets. Simulation results were compared to experimental data and accurately modeled a wide range of particle behaviors, such as particle jet waviness, spreading, break up, particle clustering and segregation, in different configurations. Simulations also accurately predicted the mean axial velocity along the centerline for both the gas phase and the solid phase, thus demonstrating the validity of the approach to model particles in turbulent flows. LES was then applied to the prediction of pulverized coal flame ignition. The stability of an oxy-coal flame as a function of changing primary gas composition (CO2 and O2) was first investigated. Flame stability was measured using optical measurements of the flame standoff distance in a 40 kW pilot facility. Large Eddy Simulations (LES) of the facility provided valuable insight into the experimentally observed data and the importance of factors such as heterogeneous reactions, radiation or wall temperature. The effects of three parameters on the flame stand-off distance were studied and simulation predictions were compared to experimental data using the data collaboration method. An additional validation study of the ARCHES LES tool was then performed on an air-fired pulverized coal jet flame ignited by a preheated gas flow. The simulation results were compared qualitatively and quantitatively to experimental observations for different inlet stoichiometric ratios. LES simulations were able to capture the various combustion regimes observed during flame ignition and to accurately model the flame stand-off distance sensitivity to the stoichiometric ratio. Gas temperature and coal burnout predictions were also examined and showed good agreement with experimental data

Canton de Saint-Antonin-Noble-Val

Date de l'opération : 1991 (PR) Inventeur(s) : Pedel I Le territoire de ce canton, situé entre le Tarn et l’Aveyron, comprend neuf communes (Castanet, Cazals, Féneyrols, Ginals, Laguépie, Parisot, Saint-Antonin-Noble-Val, Varen, Verfeil), qui n’ont livré que peu de vestiges. La prospection conduite dans le cadre d’un mémoire de maîtrise sur l’occupation du sol à l’époque médiévale n’a, en fait, révélé que peu de stations antiques : établissement gallo-romain à Féneyrols, Le Cimetière, et tro..

Canton de Saint-Antonin-Noble-Val

Date de l'opération : 1991 (PR) Inventeur(s) : Pedel I Le territoire de ce canton, situé entre le Tarn et l’Aveyron, comprend neuf communes (Castanet, Cazals, Féneyrols, Ginals, Laguépie, Parisot, Saint-Antonin-Noble-Val, Varen, Verfeil), qui n’ont livré que peu de vestiges. La prospection conduite dans le cadre d’un mémoire de maîtrise sur l’occupation du sol à l’époque médiévale n’a, en fait, révélé que peu de stations antiques : établissement gallo-romain à Féneyrols, Le Cimetière, et tro..

Analyse of e-course “Introduction to Programming” log files

Programmeerimise õpetamisel saab õppejõud tavaliselt õppijate arengust ülevaate valmis prog-rammide põhjal. Seega puudub neil sageli informatsioon õppijate lahendusprotsessi kohta. Seda eelkõige e-kursustel, kus õpilased lahendavad oma ülesandeid ilma kohalkäimiseta. La-hendusprotsessi uurimine võimaldab õppejõududel saada paremat informatsiooni õppijate kohta ja seega anda neile paremat tagasisidet. Samuti on see abiks ka õppematerjalide ja üle-sannete parandamisel.\n\rÜheks lahendusprotsessi uurimise mooduseks on Thonny kasutajate logifailide uurimine. An-tud bakalaureusetöö käigus uuritakse Thonny logifailide sisu ning luuakse programm, mis koostab iga logifaili kohta kokkuvõtte.Lectors often lack information on students’ methods of programming. It is even more rele-vant on e-courses, where students solve their exercises without attending a lecture. Therefore lecturers would need a way to help them understand students’ exercise solving.\n\rOne of these ways is to explore logfiles of Thonny’s users. This Bachelor’s thesis focuses on analysing Thonny’s log files content and making a program, which compiles a synopsis of each log file

Biochemical Trade-Offs: Evidence for Ecologically Linked Secondary Metabolism of the Sponge Oscarella balibaloi

Secondary metabolite production is assumed to be costly and therefore the resource allocation to their production should be optimized with respect to primary biological functions such as growth or reproduction. Sponges are known to produce a great diversity of secondary metabolites with powerful biological activities that may explain their domination in some hard substrate communities both in terms of diversity and biomass. Oscarella balibaloi (Homoscleromorpha) is a recently described, highly dynamic species, which often overgrows other sessile marine invertebrates. Bioactivity measurements (standardized Microtox assay) and metabolic fingerprints were used as indicators of the baseline variations of the O. balibaloi secondary metabolism, and related to the sponge reproductive effort over two years. The bioactivity showed a significant seasonal variation with the lowest values at the end of spring and in early summer followed by the highest bioactivity in the late summer and autumn. An effect of the seawater temperature was detected, with a significantly higher bioactivity in warm conditions. There was also a tendency of a higher bioactivity when O. balibaloi was found overgrowing other sponge species. Metabolic fingerprints revealed the existence of three principal metabolic phenotypes: phenotype 1 exhibited by a majority of low bioactive, female individuals, whereas phenotypes 2 and 3 correspond to a majority of highly bioactive, non-reproductive individuals. The bioactivity was negatively correlated to the reproductive effort, minimal bioactivities coinciding with the period of embryogenesis and larval development. Our results fit the Optimal Defense Theory with an investment in the reproduction mainly shaping the secondary metabolism variability, and a less pronounced influence of other biotic (species interaction) and abiotic (temperature) factors

Large Eddy Simulation of a 15MW Tangentially Oxy-Fired Pulverized Coal Boiler: Ignitor

Oxy-coal combustion, in which an O2/CO2 mixture replaces air, is one of the few possible capture technologies to enable CO2 sequestration for existing coal-fired boilers. Burning coal with relatively pure oxygen, together with recycled flue gases, can produce a highly concentrated (up to 95% CO2) flue gas stream, which makes carbon sequestration more economical. One issue of interest in rapidly implementing a strategy to retrofit existing air-fired units is to understand how replacing air by a O2/CO2 mixture changes the kinetics, aerodynamics and heat transfer of the flame. This study presents Large Eddy Simulations (LES) of a commercial scale pulverized coal boiler in oxycombustion conditions. Simulations were performed using Arches, a massively parallel LES tool developed at the University of Utah on Kraken, one of the fastest academic computer in the world on 10,000+ processors. The simulation was applied to a 15 MW boiler with tangential fired burners located in the corners under oxy-combustion conditions with an overall PO2 = 40%. Particles are tracked in an Eulerian framework with the Direct Quadrature Method of Moments (DQMOM). Coal devolatilization and char combustion are modeled and the Discrete Ordinates method is used to solve radiation. Results show that LES coupled with DQMOM has the potential to predict oxy-coal flame characteristics and to be an important tool in the retrofitting or design process of oxy-coal burners and boilers

Habitats particuliers du bathyal et de l’abyssal / SRM MO

Fiche de synthèse sur les biocénoses particulières (vulnérables) rencontrées dans les étages bathyal et abyssal de Méditerranée française (fiche réalisée dans le cadre de l'Etat Initial de la DCSMM - Sous Région Marine Méditerranée Occidentale

Biocénoses des fonds meubles du bathyal et de l’abyssal / SRM MO

Fiche de synthèse sur les biocénoses de substrats meubles rencontrées dans les étages bathyal et abyssal de Méditerranée française (fiche réalisée dans le cadre de l'Etat Initial de la DCSMM - Sous Région Marine Méditerranée Occidentale

Etat de l'art sur les indices existants concernant l'Etat Ecologique des habitats benthiques du domaine profond

Cette étude bibliographique a été réalisée par l'Ifremer Toulon (LER/PAC) dans le cadre du Bon Etat Ecologique pour la DCSMM (Directive Cadre pour la Stratégie sur le Milieu Marin). Elle est préalable à la construction d'un indicateur du Bon Etat Ecologique des communautés benthiques du domaine profond, pour lesquelles il n'existe rien actuellement