Techn. University, Diss., 2005--Darmstadt.

Zugl.: Aachen, Techn. Hochsch., Diss., 2007.

Thesis seeks to determine whether there is a statistically significant difference in the volume production of regular and irregular stemwood depending on age and stand. With growth and incremental function to determine peak volume increment depending on age levels and diameter classes. The thesis was carried out in the field Hady (forest district Bílovice nad Svitavou). The stand groups were measured representatively selected trees, which have been determined thickness and height. Then were detected statistically significant differences and prepare the growth and increment functions. With these results a method of forest regeneration of these forest stands was determined. It was found that with few exceptions was no significant difference in volume production between regular and irregular stemwood. With acquired culmination incremental function was designed way to forest regeneration, to transfer to coppice with standards forest.

In hybrid RANS/LES, Reynolds-averaged Navier-Stokes (RANS) equations method is used to treat the near-wall region and large-eddy simulation (LES) is applied to the core turbulent region. Owing to the incompatibility of these two numerical modelling approaches, an artificial (i.e., non-physical) buffer layer forms along the interface where the model switches from RANS to LES. In this thesis, a novel dynamic forcing scheme incorporating backscatter is proposed in order to remove the artificial buffer layer. In contrast to previous forcing techniques, the proposed forcing is determined dynamically from the flow field itself, and does not require any extraction of turbulent fields from reference direct numerical simulation (DNS) or high-resolution LES databases. The proposed forcing model has been tested on three types of wall-bounded turbulent flows, namely, turbulent flow in a plane channel; turbulent flow in a spanwise rotating channel; and turbulent flow in a spanwise rotating rib-roughened channel. In order to validate the present hybrid approach, turbulence statistics obtained from hybrid RANS/LES simulations are thoroughly compared with the available DNS results and laboratory measurement data. Based on the study of a plane channel flow, transport equations for the resolved turbulent stresses and kinetic energy are introduced to investigate the effects of dynamic forcing on reduction of the thickness and impact of the artificial buffer layer. As long as the dynamic forcing is in use, the artificial buffer layer have been successfully removed, indicating that the proposed hybrid approach is insensitive to the choices of the forcing region or interface location. The predictive performance of the dynamic forcing scheme has been further evaluated by considering turbulent flows subjected to a special type of body force, i.e., the non-inertial and non-conservative Coriolis force. Due to the effects of system rotation, turbulence level is enhanced on the pressure side and suppressed on the suction side of the rotating channel. Furthermore, it is reported in this thesis that the classification of the roughness type now relies not only on the pitch ratio, but also on the rotation number in the context of rotating rib-roughened flows. / February 2016

Cette thèse de doctorat porte sur les inégalités d’accès à la culture des élèves à l’école primaire. L’objet d’investigation est un dispositif créé et financé par la Ville de Paris dans les années 1990 : « les classes à Paris ». Ces dernières proposent des projets culturels et artistiques, scientifiques, d’urbanisme menés par des professionnels dans des écoles de Paris. Les enquêtes se sont déroulées dans six écoles parisiennes aux caractéristiques socioculturelles différentes. Le regard porté sur l’objet d’étude, comme la méthodologie ont été anthropologiques. Les investigations se sont fondées sur une immersion dans le dispositif et les classes et des entretiens avec l’ensemble des acteurs, en particulier les enfants. Leur rencontre fait surgir une pluralité d’imaginaires et d’attentes devant l’Ecole. Sa perspective a priori égalitaire s’en voit questionnée. / This thesis deals with the inequalities of access to culture for students of primary education. The subject was investigated through an integration into the initiative created and funded in the 90’s by Paris City Hall: “les classes à Paris”. The initiative offers scientific, urbanistic, cultural and artistic, projects led by professionals in Parisian schools. The investigations took place in six different schools. This research utilizes an anthropological methodology centered around an immersion into the initiative and classes and interviews with the actors, including the children. Their collision reveals several imaginaries and expectations from the Institution that question the perspective of equality linked to the School’s image

Teaching a foreign language using task-based language teaching (TBLT) has garnered a lot of attention and has been the object of worldwide scientific studies for the last thirty years. Few of these studies, however, include an evaluation of this method by the teachers themselves, or are conducted by them directly. My thesis, centered around the notion of task-based language learning, a teaching method recommended more and more though sometimes still snubbed, relies on my professional experience as a teacher of secondary level FLE classes in the United States and on the analysis of reference studies conducted in this field. I have adopted the methodology of research-action with the goal of offering a pedagogic intervention. First I identify certain hurdles encountered by high school foreign language teachers. After this introduction, I evaluate the methods and didactic principles that stood out to lead to a teaching philosophy centered around communication, such as task-based language teaching. The second part of the thesis presents some important studies that evaluate the pros and cons of this approach. The next section examines in turn each of three tasks offered as contrast against the traditional model consisting of presentation, practice and production, known as "PPP." Finally the last section presents my conclusions which will serve as a frame of reference for future research by other teachers.

In our everyday life, turbulence is an omnipresent phenomenon and yet remains poorly understood. Its random and chaotic nature makes it a subject almost impossible to treat from the mathematical point of view and, at present, there is no real prospect of a simple analytic theory. Scientists have therefore regarded the numerical simulation as an alternative to compute the relevant properties of turbulent flows. In this context, our thesis aims at developing and using accurate computational methods, namely pseudo-spectral methods, for studying hydrodynamic (1st part) and magnetohydrodynamic (2nd part) turbulence. In the hydrodynamic part, Chapter I introduces the governing equations of fluid mechanics as well as the main issues related to the numerical study of turbulent flows. In particular, the Direct Numerical Simulations (DNS) of turbulence, in which accurate numerical solutions of the Navier-Stokes equations are obtained, are shown to be limited to moderately turbulent flows. Chapter II introduces the Large Eddy Simulation (LES) technique which aims at simulating highly turbulent flows and which is based on a separation of scales. In practice, it consists of simulating the large - resolved - scales of the flow explicitly while modelling the small - unresolved - scales. Two different approaches for modelling the kinetic energy of the unresolved scales are proposed and their respective advantages and drawbacks are discussed. Chapter III is devoted the study of the mixing-layer using both DNS and LES. It consists of an inhomogeneous turbulent flow which has been studied experimentally and for which well-documented measurements are available. A highly accurate DNS mimicking the same experiment has been produced. It allows to study the inhomogeneity and anisotropy properties of this flow. Also, LES of the same flow, using different models, have been evaluated. In Chapter IV, we explore a pseudo-spectral method to investigate turbulence in a pipe. In this case, the method has to take into account two additional difficulties: i) the presence of the boundary and ii) the axis singularity. We detail how to circumvent these issues. The second part of the thesis is devoted to magnetohydrodynamic (MHD) turbulence. It concerns phenomena where electrically conducting flows interact with electromagnetism and for which governing equations are derived in Chapter V. In Chapter VI, a detailed analysis of the energy transfers between the magnetic and velocity fields is performed thanks to a high resolution database of homogeneous MHD turbulence. It provides some insights to understand the physics of the nonlinear interactions and is also a valuable diagnostic in the framework of LES modelling. Finally, the inhomogeneous configuration studied in Chapter III has been extended to MHD. Several statistics related to the kinetic and magnetic energies are measured and LES of this flow are performed and presented in Chapter VII.

Cette thèse étudie comment l'intégration du calcul dans les démonstrations peut les simplifier. Nous nous intéressons pour cela à la déduction modulo et à la surdéduction, deux formalismes proches dans lesquels le calcul est incorporé dans les démonstrations via un système de réécriture. Pour améliorer la recherche mécanisée de démonstration, nous considérons trois critères de simplicité. L'admissibilité des coupures permet de restreindre l'espace de recherche des démonstrations, mais elle n'est pas toujours assurée en déduction modulo. Nous définissons une procédure qui complète le système de réécriture pour, au final, admettre les coupures. Au passage, nous montrons comment transformer toute théorie pour l'intégrer à la partie calculatoire des démonstrations. Nous montrons ensuite comment la déduction modulo permet de réduire arbitrairement la taille des démonstrations, en transférant des étapes de déduction dans le calcul. En particulier, nous appliquons ceci à l'arithmétique d'ordre supérieur pour démontrer que les réductions de taille qui sont possibles en augmentant l'ordre dans lequel on se place disparaissent si on travaille en déduction modulo. Suite à ce dernier résultat, nous avons recherchés quels sont les systèmes d'ordre supérieur pouvant être simulés au premier ordre, en déduction modulo. Nous nous sommes intéressés aux systèmes de type purs et nous montrons comment ils peuvent être encodés en surdéduction, ce qui offre de nouvelles perspectives concernant leur normalisation et la recherche de démonstration dans ceux-ci. Nous développons également une méthodologie qui permet d'utiliser la surdéduction pour spécifier des systèmes de déduction. / This thesis study how computations may simplify proofs and aims to make mechanized proof search better. We are particularly interested in deduction modulo and superdeduction, two close formalisms allowing the integration of computations into proofs through a rewrite system. We consider three simplicity criteria related to proof search. Cut admissibility makes it possible to restrain the proof-search space but does not always hold in deduction modulo. We define a completion method transforming a rewrite system representing computations so that at the end cut admissibility holds. By the way, we show how to transform any first-order theory to integrate it into the computational part of proofs. We show then how deduction modulo unboundedly reduces proof lengths, by transferring deduction steps into computations. In particular, we apply this to higher-order arithmetic to show that proof-length speedups between ith- and i+1st-order arithmetic disappear when working in deduction modulo, making it possible to work in first-order logic modulo without increasing proof lengths. Following this last result, we investigate which higher-order systems can be simulated in first order using deduction modulo. We are interested by pure type systems, which are generic type systems for the lambda-calculus with dependent types. We show how these systems can be encoded in superdeduction. This offers new perspectives on their normalization and on proof search within them. We also develop a methodology to describe how superdeduction can be used to specify deductive systems.

L'objectif de cette recherche est, après analyse de la menace et des risques pesant sur le secteur des transports et des politiques menées en matière de sûreté d'envisager : la possibilité de mettre en œuvre une gouvernance de la sûreté adaptée à plusieurs modes de transport. Le champ de l'étude ayant été arrêté aux transports : aérien, maritime et terrestre. / Le résumé en anglais n'a pas été communiqué par l'auteur.

Texte remanié de: Habilitationsschrift--Philosophische Fakultät--Chemnitz, 2002. / Bibliogr. p. 299-327. Index.