École de Copenhague (physique)

Résumé

vignette|Interprétation de Copenhague dans l'expérience de pensée du chat de Schrödinger : lors d'une désintégration radioactive, il se produit une ramification de l'état. Cependant, selon un principe aléatoire, l'une des deux branches s'effondre immédiatement après que la cohérence entre les états ait suffisamment diminué, par exemple à la suite d'une mesure. L’école de Copenhague ou interprétation de Copenhague est un courant de pensée qui donne une interprétation cohérente de la mécanique quantique. Elle considère que le caractère probabiliste de la mécanique quantique et que les relations d’incertitude de Heisenberg proviennent de l’interaction entre l’appareil de mesure et ce qui est mesuré, c’est-à-dire du fait que, au niveau atomique, l’effet de l’appareil de mesure sur son objet ne peut pas être négligé. D’autre part, elle considère que parler d’objets indépendamment de toute mesure n’a pas de sens ; en particulier, il est impossible de connaître l’évolution d’un système entre

Source officielle

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Publications associées

Chargement

Personnes associées

Chargement

Unités associées

Chargement

Concepts associés

Chargement

Cours associés

Chargement

Séances de cours associées

Chargement

Calculation of geological uncertainties associated with 3-D geological models

Ian Pomian-Srzednicki

3-D geological models are built with data collected in the field such as boreholes, geophysical measurements, pilot shafts or geological mapping. Unfortunately, these data are always limited in number. It implies that geological information is sparse and subsurface models are thus always built of both subjective interpretation and mathematical interpolation/extrapolation techniques. These models are therefore uncertain and this uncertainty is rarely pointed out in a geological prognosis. Our study proposes to bring a new methodology for the evaluation of geological uncertainties related to 3-D subsurface models and to test its potential use. The methodology we propose is based on the 3-D subsurface model, which is here considered as the most probable prediction (notion of best guess). The various geological interfaces that compose the subsurface model are handled individually as Gaussian random fields. At each location of an interface, the random function Z(u) describing the position of this interface is composed of a deterministic part m(u) which represents the expected position, and a random part σ(u)ε(u) which describes fluctuations around the predicted position. Then, a model of spatial variability (a variogram function γ(h)) is proposed in order to condition the random field according to available observations. Several structural constraints, such as the shape of folds and the thickness of layers can also be accounted for in this model. At this point, we are able to estimate the local variance all over the study area by the application of the kriging technique. Finally, the variability is converted into three-dimensional information by calculating probabilities, this describes the occurrence of the various rock masses that are present in the study area. The probabilities are calculated according to intersection rules that govern the stratigraphic sequence of the subsurface model, and they allow us to build a probabilistic model of subsurface structures in the form of a three-dimensional probability field. All of this has been incorporated in a computer program.

EPFL2002

Chargement

Purpose The purpose of this paper is to examine how the emergent 3D interactive media technologies are used as a viable tool for enhancing visitors' overall experiences at an exhibition entitled, 300 Years of Hakka Kungfu - Digital Vision of Its Legacy and Future (Hakka Kungfu Exhibition) - presented and co-organized by the Intangible Cultural Heritage Office of Hong Kong, International Guoshu Association and the School of Creative Media, City University of Hong Kong. Design/methodology/approach A questionnaire survey in both online and paper-based formats was used for identifying visitors' experiences in the interactions with the multimedia technologies. For this research study, a questionnaire, consisting of 26 items, was set out to measure the visitors' experiences at the Exhibition. Since the Exhibition was about presenting a centuries-old Chinese cultural heritage, Hakka Kungfu via the use multimedia technologies, in the context of establishing a dialogue between the past and present, the researchers included questionnaire items that were devoted to enquire about the level of understanding, knowledge and enjoyment, and visitors' new knowledge about Hong Kong history and culture was successfully disseminated to the respondents at the end of the questionnaire. Findings A total of 209 completed questionnaires were collected at this Hakka Kungfu Exhibition. The findings reveal that the exhibits did attract people at all ages. This Exhibition gave the visitors a sense of interest and wonder in the object and information presented in the Exhibition. Findings of this study also reveal that this Exhibition has successfully attracted a large number of female visitors, as well as visitors who have never taken any martial arts training. In addition, visitors' Exhibition experience was found to be memorable, as well as enjoyable. Furthermore, visitors' experience within the Exhibition suggested that it was entertaining, as well as educational. By creating a long-lasting impact on the minds of these Exhibition visitors about the connections between and relevance of traditional Chinese Kungfu, their collective cultural identity, as well as the contemporary society we live in. The Exhibition exemplified the successful integration of the presentation of Kungfu as a form of cultural heritage with engagement-creating technology, in which technology is unobtrusive but effective. Originality/value Although it is already a global trend for the museums to integrate multimedia technologies into their exhibitions, research on the situation and feedback of multimedia technology used in the museum exhibitions in Hong Kong is scarce as well as scattered. Findings of this study could help identify various factors involved in audience participation, thereby exploring the possibility of building a contact point/space for traditional Chinese Kungfu as an intangible cultural heritage, via the integration of the latest media technologies. In particular, the development of multimedia technologies has become increasingly important to museums, and museum professionals have been exploring how digital and communication technologies can be developed to offer visitors a more interactive, personalized museum experience. In general, despite the growing interest in deploying digital technology as interpretation devices in museums and galleries, there are relatively few studies that examine how visitors, both alone and with others, use new technologies when exploring the museum contents.

EMERALD GROUP PUBLISHING LTD2019

Chargement

Multi-scale modeling of aggregate interlock phenomena in concrete

Mohit Pundir

In concrete structures, opened cracks contribute significantly to the transfer of shear and normal stresses through the contact forces occurring between fractured surfaces. Such contact forces are due to protruding asperities, engaged by interlocking and friction. This physical phenomena, termed as Aggregate Interlock, contributes significantly to the shear-strength of cracked concrete structures. The complex phenomenon depends on the topography of cracked surfaces, where material protruding from one side may engage with the opposite one. Various analytical models have been proposed to determine and quantify the contact stresses developing due to aggregate interlock. However, these analytical models do not include the full aspect of the problem such as roughness of crack surfaces at different length scales, elasto-plastic deformation of crack surfaces and process of fracture and interlock simultaneously occurring along the crack surfaces. Therefore,the aim of this thesis, is to investigate the role of such parameters in determining the contact stresses by numerically modeling of contact between concrete surfaces using numerical framework such as Boundary Integral method and Finite Element method. This research proposes to statistically analyze the influence these parameters have on the overall shear-strength of concrete and to use the information thus gained for improving upon the existing analytical-models. The first part of this objective is to better understand the consistency of the widely used analytical approaches such as Two-Phase model and particularly of the physical interpretation of the fitting parameters usually employed to match the experimental results. This thesis suggests an extension of the model by introducing the induced surface alterations (elasto-plastic deformation, degradation of matrix material), which allows accurate semi-analytic predictions of shear stress resistance. The proposed model is further strengthened by a number of tailored experiments, comprising concrete with various aggregate sizes, and various loading kinematics. The second part of the objective is to investigate the role small-scale roughness, at micro-scale, of a crack in concrete plays. In this thesis, we propose a methodology to numerically generate representative rough surfaces in concrete while prescribing characteristic signatures of real concrete surfaces. With help of numerical modeling of contact between such representative surfaces, it is shown that inclusion of small-scale roughness eliminates the need of any fitting parameter, making it a reliable and physically-based method for predicting shear transfer phenomena in concrete. An empirical power-law predicting the shear resistance in concrete is a direct outcome, which accounts for micro-scale roughness and aggregate distribution. The complex problem of aggregate interlock is generally simplified as a problem of two completely fractured surfaces coming in contact. However, the contact between surfaces occurs simultaneously along the fracture process. Therefore, the third part of this thesis is to account for the simultaneous process of fracture and contact between fracturing surfaces. A new numerical framework is developed that couples cohesive zone modeling, representing fracture, and a Node-to-segment contact algorithm to handle normal and frictional contact conditions. The proposed model allows to handle contact between the newly cracked surfaces.

EPFL2021

Chargement