COMPUTATIONAL MODELLING OF HUMAN AESTHETIC PREFERENCES IN THE VISUAL DOMAIN: A BRAIN-INSPIRED APPROACH

Following the rise of neuroaesthetics as a research domain, computational aesthetics has also known a regain in popularity over the past decade with many works using novel computer vision and machine learning techniques to evaluate the aesthetic value of visual information. This thesis presents a new approach where low-level features inspired from the human visual system are extracted from images to train a machine learning-based system to classify visual information depending on its aesthetics, regardless of the type of visual media. Extensive tests are developed to highlight strengths and weaknesses of such low-level features while establishing good practices in the domain of study of computational aesthetics. The aesthetic classification system is not only tested on the most widely used dataset of photographs, called AVA, on which it is trained initially, but also on other photographic datasets to evaluate the robustness of the learnt aesthetic preferences over other rating communities. The system is then assessed in terms of aesthetic classification on other types of visual media to investigate whether the learnt aesthetic preferences represent photography rules or more general aesthetic rules. The skill transfer from aesthetic classification of photos to videos demonstrates a satisfying correct classification rate of videos without any prior training on the test set created by Tzelepis et al. Moreover, the initial photograph classifier can also be used on feature films to investigate the classifier’s learnt visual preferences, due to films providing a large number of frames easily labellable. The study on aesthetic classification of videos concludes with a case study on the work by an online content creator. The classifier recognised a significantly greater percentage of aesthetically high frames in videos filmed in studios than on-the-go. The results obtained across datasets containing videos of diverse natures manifest the extent of the system’s aesthetic knowledge. To conclude, the evolution of low-level visual features is studied in popular culture such as in paintings and brand logos. The work attempts to link aesthetic preferences during contemplation tasks such as aesthetic rating of photographs with preferred low-level visual features in art creation. It questions whether favoured visual features usage varies over the life of a painter, implicitly showing a relationship with artistic expertise. Findings display significant changes in use of universally preferred features over influential vi abstract painters’ careers such an increase in cardinal lines and the colour blue; changes that were not observed in landscape painters. Regarding brand logos, only a few features evolved in a significant manner, most of them being colour-related features. Despite the incredible amount of data available online, phenomena developing over an entire life are still complicated to study. These computational experiments show that simple approaches focusing on the fundamentals instead of high-level measures allow to analyse artists’ visual preferences, as well as extract a community’s visual preferences from photos or videos while limiting impact from cultural and personal experiences

Strength of a matrix with elliptic criterion reinforced by rigid inclusions with imperfect interfaces

International audienceElliptic effective strength criteria in the mean-deviatoric stress plane are encountered in porous media for a granular material made of rigid grains with cohesive frictional interfaces or a material with pores in a Drucker-Prager matrix. The macroscopic strength criterion of a heterogeneous material comprising a matrix with elliptic strength criterion reinforced by rigid inclusions with perfect or imperfect interfaces is studied. Considered imperfect interfaces follow either a Tresca or a Mohr-Coulomb strength criterion. Derived macroscopic criteria are shown to be a combination of a larger ellipse, which corresponds to the criterion for perfectly bounded interfaces, conditionally truncated by a smaller ellipse resulting from the activation of interfacial mechanisms. The activation of the interfacial mechanisms depends on the matrix and interfaces strength properties, inclusions concentration, as well as the macroscopic strain triaxiality ratio

Méthode de calcul multi-échelle pour la prédiction de l'apparition des contraintes résiduelles dans le procédé d'empilement par soudage et consolidation en continu

Le procédé d'empilement par soudage et consolidation en continu est un procédé prometteur utilisé dans l'industrie aéronautique pour fabriquer des pièces de grande taille. Dans les conditions standard d'élaboration, les pièces réalisées par ce type de procédé sont le siège d'importantes contraintes résiduelles. Le manque de connaissances sur l'origine et le développement des contraintes résiduelles est un frein important à la validation industrielle de ce procédé. On propose dans cette étude de développer une méthode de calcul multi-échelle permettant d'évaluer la formation des contraintes résiduelles au cours du procédé. Cette méthode, basée sur l'utilisation de la méthode des « éléments naturels » et de la méthode de Karhunen-Loeve, prend en compte l'évolution des propriétés thermomécaniques du matériau au cours du procédé, qui est facteur prépondérant dans la formation des contraintes résiduelles

Pertinences et impuissances d’une politique globale de changement autour des TICE face aux stratégies d’acteurs

Cet article présente le déploiement de l’Environnement Numérique de la Formation Initiale de Télécom Paris à la fois comme un élément inscrit de manière plus globale dans une politique de changement organisationnel menée par l’école, un instrument de ce changement et un objet socio-technique que les enseignants-chercheurs s’approprient. Par conséquent, si innovation pédagogique il y a, elle est moins liée à l’institutionnalisation du changement qu’aux initiatives locales et utilisations novatrices qui permettent d’appréhender un cours d’une manière différente.This paper presents the implementation of a web-based system for the academic programs at Telecom Paris, as a part of the policy of organizational change led by the school, an instrument of this change and a socio-technical object that the academic staff appropriates. As a result, if pedagogic innovation there is, it is less linked to the institutionalisation of change than to local initiatives and to the innovative uses which allow to teach in a different way

Calcium isotope (δ^44/40Ca ) variations of Neogene planktonic foraminifera

Measurements of the calcium isotopic composition (δ44/40Ca) of planktonic foraminifera from the western equatorial Pacific and the Indian sector of the Southern Ocean show variations of about 0.6‰ over the past 24 Myr. The stacked δ44/40Ca record of Globigerinoides trilobus and Globigerina bulloides indicates a minimum in δ44/40Casw (seawater calcium) at 15 to 16 Ma and a subsequent general increase toward the present, interrupted by a second minimum at 3 to 5 Ma. Applying a coupled calcium/carbon cycle model, we find two scenarios that can explain a large portion of the observed δ44/40Casw variations. In both cases, variations in the Ca input flux to the ocean without proportional changes in the carbonate flux are invoked. The first scenario increases the riverine calcium input to the ocean without a proportional increase of the carbonate flux. The second scenario generates an additional calcium flux from the exchange of Ca by Mg during dolomitization. In both cases the calcium flux variations lead to drastic changes in the seawater Ca concentrations on million year timescales. Our δ44/40Casw record therefore indicates that the global calcium cycle may be much more dynamic than previously assumed

From Computational Aesthetic Prediction for Images to Films and Online Videos

In the last decade, creating and sharing videos online has become a mainstream movement and has led to some creators generating one personal video per day, also called daily vlogging. Although robust solutions exist to suggest photographs based on aesthetic criteria, the rising number of online videos created and watched means that such recommendation systems are required more than ever for videos. The main purpose of this paper is to transfer the skill of computational aesthetic classification of photographs to videos while developing new ways of investigating video creation. Using a dataset of photographs rated on aesthetic criteria by an internet community and recently developed feature extraction algorithms, the computational aesthetic classifier is capable of state-of-the-art photograph classification depending on aesthetic preferences learnt from people’s ratings. On a test set of YouTube videos, the same system then displays satisfying aesthetic classification results that consist of an attempt to match the provided human aesthetic quality ratings. Achieving a transfer of skill from photograph to video classification, the computational classifier is used to analyze the evolution of aesthetics in feature films; this highlighted the aesthetic classifier’s visual preferences and caused some interesting patterns to emerge that were related to filmmakers’ decisions. Aesthetic classification makes it possible to observe the evolution of aesthetics over the careers of daily content creators thanks to their abundant and regular online video content. It can aid the investigation into the impact of aesthetics on the popularity of online videos using the available meta-data about the internet audience’s appreciation. This can also provide a new tool for video content creators to assess their work and assist them in the production of content of higher aesthetic quality

Étude de l'apparition des contraintes résiduelles dans le procédé d'empilement par soudage et consolidation en continu de composites thermoplastiques

The automated two placement process developed in the aircraft industry is an emerging technique for manufacturing continuous fiber-reinforced thermoplastic parts. Our objective is to model the appearance of residual stress in the process. The originality of the study was to develop a multi-scale and multi-physics numerical modeling allowing a coupling between the two scales in order to model the residual stress appearance during the process. The microscopic level, which is described by the constrained natural elements method (CNEM), provides the macroscopic scale the thermomechanical properties of the homogenized material at each time step. The macroscopic scale provides the microscopic scale the boundary conditions (temperatures, displacements), which allow to determine the temperature, strain and stress microscopic fields during the process. The results in terms of validation and implementation of the method to the automated two placement process are satisfactory and promising. The developed numerical method can moreover be easily applied to other types of forming processes of thermoplastic composites.Nos travaux se sont intéressés à la modélisation de l'apparition des contraintes résiduelles dans le procédé d'empilement par soudage et consolidation en continu développé dans l'industrie aéronautique. Dans les conditions standard d'élaboration, les pièces réalisées par ce type de procédé sont le siège d'importantes contraintes résiduelles. L'ignorance de leur origine et développement est un frein important à la validation industriel de ce procédé prometteur. Dans cette perspective, l'originalité de l'étude a été de développer une méthode de modélisation numérique multi-échelle et multi-physique permettant de réaliser une modélisation couplée aux échelles macroscopique et microscopique du phénomène de l'apparition des contraintes résiduelles, au cours du procédé. L'échelle microscopique, décrite à l'aide de la méthode des éléments naturels contraints (CNEM), apporte à l'échelle macroscopique les propriétés thermomécaniques homogénéisées du matériau à chaque pas de temps. L'échelle macroscopique apporte à l'échelle microscopique les conditions aux limites (températures, déplacements), qui permettent de déterminer les champs de température, de déformation et de contrainte microscopiques dans le matériau au cours du temps. Les résultats obtenus en terme de validation et d'application de la méthode au procédé d'empilement par chauffage et consolidation en continu sont satisfaisants et prometteurs. La méthode développée peut de plus être aisément appliquée à d'autres types de procédé de mise en forme des composites thermoplastiques

La rétinopathie diabétique au quotidien (les difficultés de l'autosurveillance)

CAEN-BU Médecine pharmacie (141182102) / SudocLYON1-BU Santé (693882101) / SudocSudocFranceF

Étude de l'apparition des contraintes résiduelles dans le procédé d'empilement par soudage et consolidation en continu de composites thermoplastiques

Nos travaux se sont intéressés à la modélisation de l'apparition des contraintes résiduelles dans le procédé d'empilement par soudage et consolidation en continu développé dans l'industrie aéronautique. Dans les conditions standard d'élaboration, les pièces réalisées par ce type de procédé sont le siège d'importantes contraintes résiduelles. L ignorance de leur origine et développement est un frein important à la validation industriel de ce procédé prometteur. Dans cette perspective, l'originalité de l étude a été de développer une méthode de modélisation numérique multi-échelle et multi-physique permettant de réaliser une modélisation couplée aux échelles macroscopique et microscopique du phénomène de l'apparition des contraintes résiduelles, au cours du procédé. L échelle microscopique, décrite à l aide de la méthode des éléments naturels contraints (CNEM), apporte à l'échelle macroscopique les propriétés thermomécaniques homogénéisées du matériau à chaque pas de temps. L échelle macroscopique apporte à l'échelle microscopique les conditions aux limites (températures, déplacements), qui permettent de déterminer les champs de température, de déformation et de contrainte microscopiques dans le matériau au cours du temps. Les résultats obtenus en terme de validation et d'application de la méthode au procédé d'empilement par chauffage et consolidation en continu sont satisfaisants et prometteurs. La méthode développée peut de plus être aisément appliquée à d'autres types de procédé de mise en forme des composites thermoplastiques.The automated two placement process developed in the aircraft industry is an emerging technique for manufacturing continuous fiber-reinforced thermoplastic parts. Our objective is to model the appearance of residual stress in the process. The originality of the study was to develop a multi-scale and multi-physics numerical modeling allowing a coupling between the two scales in order to model the residual stress appearance during the process. The microscopic level, which is described by the constrained natural elements method (CNEM), provides the macroscopic scale the thermomechanical properties of the homogenized material at each time step. The macroscopic scale provides the microscopic scale the boundary conditions (temperatures, displacements), which allow to determine the temperature, strain and stress microscopic fields during the process. The results in terms of validation and implementation of the method to the automated two placement process are satisfactory and promising. The developed numerical method can moreover be easily applied to other types of forming processes of thermoplastic composites.PARIS-Arts et Métiers (751132303) / SudocSudocFranceF

Boron as a proxy of the evolution of primary mineral weathering mechanisms: from the bedrock to the surface

International audienc