Zugl.: Dresden, Techn. Univ., Diss., 2006

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2004. / Härtill 4 uppsatser.

Zugl.: Zürich, Univ., Diss., 2007

Dissertation. / Description based on print version record. Includes bibliographical references (p. 564-586) and indexes.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 179-187).

L’objectif de ma thèse est de proposer une étude approfondie d’un domaine qui, s’il est régulièrement employé pour la vulgarisation de l’Archéologie et de l’Histoire, n’a jamais fait jusqu’à présent à notre connaissance l’objet d’une étude spécifique. La restitution archéologique et historique est pourtant un phénomène qui, en particulier dans les pays anglo-Saxons et nordiques, joue un rôle-Clé à la fois dans la recherche scientifique et dans la diffusion du patrimoine auprès du grand-Public. Des articles et des ouvrages qui s’intéressent à telle ou telle méthode de restitution sont fréquemment publiés en France. Ce travail de recherche se développe en trois parties : la première est consacrée à une Histoire de la restitution et des représentations du passé, à travers l’espace et le temps. De l’Antiquité à aujourd’hui, nous étudierons ainsi l’évolution des mises en scène et des mises en images des évènements, édifices et figures marquantes de l’Histoire, de même que des valeurs et des interdits rattachés à ces représentations du passé. Donner une image, réaliste ou symbolique, du passé et ne pas seulement l’évoquer par la parole ou par l’écrit, est un désir qui semble avoir été présent chez les hommes à toutes les époques et dans toutes les civilisations. Miroir des époques qui les ont créées et de la perception qu’ont les hommes de leur société et de celles qui les ont précédés, les restitutions historiques et archéologiques anciennes sont des témoignages importants. La seconde partie repose sur l’analyse de trois exemples de restitutions archéologiques et historiques réalisées en France et sur des sites européens. Ils ont été choisis pour leur caractère paradigmatique et leurs places respectives dans l’avancée des techniques et des attentes des scientifiques comme du public destiné à les regarder. Enfin, la troisième et dernière partie va au cœur du sujet et, en particulier, à partir des exemples analysés précédemment, propose une interrogation sur les limites et les enjeux de la restitution archéologique et historique. Cette mise en question revêt une particulière actualité à la fin du XXème et au début du XXIème siècle. Cela pour trois raisons : le développement du tourisme culturel et le développement des parcs archéologiques interactifs, l’amplification des politiques du patrimoine, l’accroissement d’un public formé à la lecture de l’image qui n’attend plus seulement du chercheur le résultat d’une hypothèse mais aussi sa justification. Les enjeux de la restitution sont donc cruciaux. Un signe en est que de plus en plus de thèses d’archéologie sur des études de sites proposent des restitutions. Les autorités archéologiques de nombreux pays stipulent désormais qu’une part conséquente du budget de la fouille doit être consacrée à la valorisation postérieure, au centre de laquelle se trouve la restitution. Cette dernière sort donc du cadre strict de la muséographie et s’impose désormais à des acteurs très divers, qui n’ont été que superficiellement intéressés à ces problématiques. L’explosion du recours à la restitution apparaît comme un triomphe ambigu. En effet, les divers acteurs qui utilisent la restitution ne poursuivent pas les mêmes buts : entre ceux qui expérimentent une hypothèse de travail et ceux qui attendent un support pédagogique pour instruire, voire ceux qui recherchent une image destinée à susciter l’investissement sentimental du lieu, le dénominateur commun est très difficile, voire impossible, à trouver. En outre une des limites majeures des restitutions archéologiques et historiques réside principalement dans à leur caractère éphémère de leur validité scientifique, alors que leur durée de vie est parfois très longue. Une historiographie de ces réalisations est nécessaire en ce qu’elles reflètent au moins autant leur contexte de construction que l’époque qu’elles sont supposées faire revivre. / The aim of my thesis was to offer a detailed study of an area which, if regularly used for the extension of Archaeology and History, has never been so far the subject of a specific study, according to our knowledge. Archaeological and historical reconstruction is nevertheless a phenomenon, especially in the Anglo-Saxon and Scandinavian countries, that plays a key role in both scientific research and release of heritage to the general public. Articles and books that are interested in this or that method of reconstruction are frequently published in France.This research work is divided in three parts: the first one is devoted to a historic of reconstruction and representations of the past, through space and time. From antiquity to today, we will study the evolution of staging and set images on events, buildings and figures in history, as well as values and taboos associated to these representations of the past. Give a picture, realistic or symbolic of the past and not only allude to it by spoken or written means, is a desire that seems to have been present among men in all ages and in all civilizations. Mirrors of the eras that created them and perceptions of the men of their own society and those who preceded them, ancient historical and archaeological reconstructions are important testimony. The second part is based on the analysis of three examples of archaeological and historical representation made in France and on European sites. They were chosen for their paradigm and their respective places in the advanced techniques and expectations of scientists as well as the public supposed to watch them. The third and last part goes to the heart of the subject and, in particular, from the examples discussed above, offers an interrogation upon the limits and the challenges of archaeological and historical reconstructions. This issue is particularly topical in the late twentieth and early twenty-First century. For three reasons: the development of cultural tourism and the development of interactive archaeological parks, the amplification of heritage policies, the increase in the public educated in image reading which is waiting not only for the researcher’s result of a hypothesis but also its justification. So the reconstruction issues are crucial. A sign of it is that more and more doctoral thesis of archeological sites offers reconstructions. The archaeological authorities of many countries now stipulate that a significant proportion of the budget of the search must be devoted to subsequent promotion, of which the center is reconstruction. The latter therefore falls outside the strict framework of museums and now requires a variety of actors who were only superficially interested in these issues. The explosion in use of reconstructions appears as an ambiguous triumph. Indeed, the various actors who use the reconstruction are not aiming the same goals: between those who experience a working hypothesis and those who are expecting pedagogical resource as teaching tools, or those looking for an image to generate a sentimental investment of a place, the common denominator is very difficult, if not impossible, to find. In addition, a major limitation of archaeological and historical reconstructions lies mainly in the ephemeral nature of their scientific validity, even if their life is sometimes very long. An historiography of these achievements is necessary, because they reflect the context of their building as much as the era they are supposed to bring back to life.

Granular media continue to be among the most manipulated materials found in various industries. Particle interactions in granular flow has fundamental importance in analyzing the performance of a wide range of key engineering applications such as hoppers, tumblers, and mixers etc. In spite of such ubiquitous presence, till date, our understanding of the granular flow is very limited. This restricts our ability to design efficient and optimal granular processing equipment. Additionally, the existing design abilities are also constrained by the number of particles to be analyzed, where, a typical industrial application involves millions of particles. This motivated the current research where investigations on the above limitations are pursued from three different angles: experimental, theoretical, and simulation. More specifically, this work aims to study particle-wall interaction and developing a computationally efficient cellular automata simulation framework for industrial granular applications. Towards this end, the current research is divided into two part: (I) energy dissipation during particle-wall interaction (II) cellular automata modeling. In part I, detailed experiments are performed on various sphere-thin plate combinations to measure the coefficient of restitution (COR) which is a measure of energy dissipation and it is one of the most important input parameters in any granular simulation. Alternatively, the energy dissipation measure also used to evaluate the elastic impact performance of superelastic Nitinol 60 material. Explicit finite element simulations are performed to gain detail understanding of the contact process and underlying parameters such as contact forces, stress-strain fields, and energy dissipation modes. A parametric study reveals a critical value of plate thickness above which the effect of plate thickness on the energy dissipation can be eliminated in the equipment design. It is found that the existing analytical expressions has limited applicability in predicting the above experimental and numerical results. Therefore, a new theoretical model for the coefficient of restitution is proposed which combines the effect of plastic deformation and plate thickness (i.e. flexural vibrations). In part II, in order to advance the existing granular flow modeling capabilities for the industry (dry and slurry flows) a cellular automata (CA) modeling framework is developed which can supplement the physically rigorous but computationally demanding discrete element method (DEM). These include a three-dimensional model which takes into account particle friction and spin during collision processing, which provides the ability to handle flows beyond solely the kinetic regime, and a multiphase framework which combines computational fluid dynamics (CFD) with CA to model multi-million particle count applications such as particle-laden flows and slurry flows.

L’objectif de cette étude est de caractériser le bruit de graillonnement des boîtes de vitesses automobiles, qui résulte des chocs entre les pignons au niveau des rapports non engagés, sous l’effet des fluctuations de vitesses imposées par le moteur. Outre les paramètres de conception de la boîte de vitesses et les conditions de fonctionnement, les paramètres qui gouvernent la réponse dynamique des pignons fous sont les couples de traînée et les caractéristiques des contacts qui gouvernent les chocs entre dents. Un modèle numérique non linéaire a été élaboré pour caractériser la réponse dynamique d’un pignon fou. Il permet d’identifier le seuil d’excitation au-delà duquel le phénomène de graillonnement apparaît et de qualifier la très grande diversité de comportements dynamiques susceptibles d’être observés, en fonction du niveau d’excitation adimensionnée, du jeu de denture et du coefficient de restitution des chocs entre dents. Les paramètres inconnus ont été identifiés expérimentalement, grâce à l’exploitation d’un banc d’acyclisme et l’implémentation de codeurs optiques sur les pignons menant et fou. Des essais en réponse libre amortie ont permis de discriminer les différentes sources de dissipation(roulements, palier du pignon fou, barbotage, etc.) et de valider les modèles permettant d’identifier le couple de traînée s’exerçant sur chaque pignon fou. D’autres essais en régime de fonctionnement stationnaire ont permis de décrire le coefficient de restitution des chocs entre les pignons, sa dispersion et sa variation avec la vitesse d’impact. Les mesures effectuées sous une excitation maîtrisée ont permis de caractériser le comportement dynamique du pignon fou et de valider les hypothèses retenues et les résultats numériques obtenus par le modèle non linéaire, recalé à partir des paramètres préalablement identifiés. Enfin, l’analyse du transfert entre les impulsions générées au niveau des pignons et la réponse vibratoire du carter a permis d’évaluer expérimentalement et numériquement le critère qui qualifie le bruit de graillonnement rayonné par la boîte de vitesses. La mise en oeuvre du modèle numérique permet d’analyser l’influence des paramètres de conception de la boîte de vitesses et de proposer des solutions qui minimisent le graillonnement, pour l’ensemble des rapports de la boîte et des conditions de fonctionnement. / The aim of this work is to characterize the rattle noise of automotive gearboxes, resulting from impacts between toothed wheels of unselected gear ratios. Dynamic response of idle gears firstly depends on design parameters and engine operating conditions. The unknown parameters are the drag torque acting on the idle gear and characteristics of impacts between teeth.A non linear dynamic model has been developed in order to identify dynamic response of idle gears. It allows identification of excitation threshold beyond which rattle noise rises, and describes the wide variety of dynamic behaviors that are likely to appear, depending on the dimensionless excitation amplitude, the clearance between gears and the restitution coefficient of impacts between teeth. The unknown parameters have been identified experimentally through implementation of optical encoders in the gearbox and the operation of a specific acyclism test bench. Analysis of the free damped response of the gearbox allowed discrimination of the different dissipation sources (bearings, connection between idle gear and shaft, churning, etc.). Models proposed to identify the drag torque have been validated. Further tests under stationary operating conditions allowed measurement of the restitution coefficient of impacts and its velocity dependent probability density function. Experiments under controlled excitation were used to characterize the dynamic behavior of the idle gear and validate the assumptions and the numerical results obtained from the non linear dynamic model, fitted with the parameters previously identified. Finally, the transfer between the impulses generated at the gears and the housing vibration has been investigated to evaluate experimentally and numerically the criterion used to describe the rattle noise radiated from the gearbox. The implementation of the model allows analysis of the influence of the gearbox design parameters and solutions that minimize rattle noise can be proposed for all gear ratios and operating conditions of the gearbox.

The master's thesis deals with the animation of the historic monasteries in the Czech Republic. On the selected examples the practical part of the master's thesis explores the possibilities and the limits of the sociocultural use of the monastic buildings in today's society. The master's thesis also responds to the current events and it brings the summary of the issues of the state property settlement with churches which significantly affects the activities of the religious orders. There are also examples of the successful international animation projects in the master's thesis.

Masters of Commerce / In South Africa land dispossession and land appropriation were legally instituted with the promulgation of the 1913 and 1936 Land Acts and the 1950 Group Areas Act that saw the forced removal of the majority of Black South Africans from their homes and livelihoods. This policy of racial segregation left in its wake countless examples of families and entire communities being uprooted and forced to eke out an existence on land that often had no or little potential for development. The Tswana people who resided on the farm Schmidtsdrift in the Northern Cape is an example of a community that was forced to relocate to a barren piece of land called Kuruman about 140km from Schmidtsdrift. In 1994 with South Africa’s first democratic elections, a number of policy changes were affected that sought to undo the injustice of the past. The Land reform programme initiated by the government provided the Tswana people an opportunity to reclaim their land under the Land Restitiition Act o2 of 1994. The new policy changes were certainly far reaching in addressing the legacy of landlessness but it became clear four years after the initiation of the programme that serious delays with regard to the finalisation of the claims were being experienced. By 1998 only 9 claims of the 26 000 claims lodged with the Commission on the Restitution of Land Claims were finalised. One of the claims that were still awaiting finalisation at this stage was the Schmidtsdrift claim lodged by the Tswana community in November 1996. It is within this landscape of challenges faced by the land restitution process that this research report examined the obstacles, specifically: from 1996 to 1998, experienced by the Schmidtsdrift Restitution Case with regard to the settlement of their claim.