Literatura académica sobre el tema "Préservation des structures fines"
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Artículos de revistas sobre el tema "Préservation des structures fines"
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Tester, Robert E. y Paul N. Gaskin. "Effect of fines content on frost heave". Canadian Geotechnical Journal 33, n.º 4 (20 de agosto de 1996): 678–80. http://dx.doi.org/10.1139/t96-092-313.
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In regions of seasonal frost the integrity of pavement structures is dependent on the resistance of base and subbase soils to frost action. This note describes the results of performing the U.S. Army Cold Regions Research and Engineering Laboratory CRREL II laboratory freezing test on a crushed limestone with a varying fines content. Frost heave increased linearly as fines content increased. Under the CRREL frost susceptibility criterion, the crushed gravel was satisfactory with up to 8% fines. A greater fines content resulted in an unsatisfactory classification. Key words: frost susceptibility, fines content, road base.
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Breton, Gérard. "The Actinomycetales of the Sparnacian amber from Corbières (Aude, France): taphonomy and diversity". Annales de la Société Géologique du Nord, n.º 17 (1 de diciembre de 2010): 3–22. http://dx.doi.org/10.54563/asgn/1207.
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Les sédiments sparnaciens de Douzens (Aude, France) ont livré de nombreux fragments d’ambre. L’examen au microscope optique de cet ambre a révélé la présence d’actinomycètes nombreux et variés. Deux genres nouveaux, Thermomonosporopsis et Thermomonosporites et huit espèces nouvelles, Thermomonosporopsis waggoneri, T. tenuis, Thermomonospora corbarica, Thermomonosporites arcuatus, Nocardia ? cousini, N. ? crispa, Actinoplanes ? girardi, et Streptomyces vizcainoi sont décrits sur la base de caractères morphologiques, de la préservation de structures reproductrices (spores, sporanges, rameaux sporifères), de la dualité éventuelle des mycéliums et de structures de multiplication (fragmentation du mycélium). A côté du piégeage dans la résine, un processus taphonomique original est décrit : au moins une espèce a été capable de coloniser la surface de la résine et de croître dans cette résine.
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Breton, Gérard. "The Actinomycetales of the Sparnacian amber from Corbières (Aude, France): taphonomy and diversity". Annales de la Société Géologique du Nord, n.º 17 (1 de diciembre de 2010): 3–22. http://dx.doi.org/10.54563/asgn.1207.
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Les sédiments sparnaciens de Douzens (Aude, France) ont livré de nombreux fragments d’ambre. L’examen au microscope optique de cet ambre a révélé la présence d’actinomycètes nombreux et variés. Deux genres nouveaux, Thermomonosporopsis et Thermomonosporites et huit espèces nouvelles, Thermomonosporopsis waggoneri, T. tenuis, Thermomonospora corbarica, Thermomonosporites arcuatus, Nocardia ? cousini, N. ? crispa, Actinoplanes ? girardi, et Streptomyces vizcainoi sont décrits sur la base de caractères morphologiques, de la préservation de structures reproductrices (spores, sporanges, rameaux sporifères), de la dualité éventuelle des mycéliums et de structures de multiplication (fragmentation du mycélium). A côté du piégeage dans la résine, un processus taphonomique original est décrit : au moins une espèce a été capable de coloniser la surface de la résine et de croître dans cette résine.
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Diouf, Antonin Benoît. "Le patrimoine documentaire comme soubassement d’un développement durable". Documentation et bibliothèques 63, n.º 3 (12 de septiembre de 2017): 18–23. http://dx.doi.org/10.7202/1041019ar.
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Le présent article vise à démontrer le lien qui existe entre les bibliothèques et le concept de développement durable. Il se concentre sur la nécessaire préservation du patrimoine documentaire pour favoriser un développement durable au bénéfice des générations futures. Le patrimoine documentaire a valeur de source d’inspiration pour toute action à venir et tout doit être mis en oeuvre pour que sa préservation soit durable pour une infinité temporelle. Cela est d’autant plus important dans un contexte africain où le développement représente le défi ultime de l’ensemble des pays du continent. L’argumentaire du présent article se base sur la réalité vécue dans une bibliothèque patrimoniale panafricaine confrontée à un sérieux problème de conservation de ses collections, une situation partagée avec bien d’autres structures documentaires du même type. Ses collections qui représentent une part de la mémoire gouvernementale africaine post-indépendante sont mises en péril par des agents de dégradation biologiques et physiques, hypothéquant ainsi leur accès par les futures ressources humaines d’Afrique. Tout en montrant le lien évident entre accès à l’information et développement – comme l’a si bien compris l’IFLA, qui a imposé cet élément parmi les sous-objectifs des Objectifs du développement durable (ODD) –, l’exposé cherche aussi à montrer que les bibliothèques et les structures assimilées peuvent promouvoir le développement durable, non pas seulement en matière d’appropriation de techniques architecturales écologiquement rentables, mais aussi de comportements responsables dans la prise en compte des risques environnementaux. Pour ce faire, les bibliothèques doivent s’adapter aux législations nationales et transnationales en matière d’environnement pour conformer leurs services et modes de fonctionnement aux desiderata de ces dernières, ce qu’il est souvent difficile d’accomplir dans un contexte africain.
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J, Castillo. "Biogenic SiO2 Nanoparticle-based Nanofluid for Fines Migration Control". Petroleum & Petrochemical Engineering Journal 7, n.º 1 (11 de enero de 2023): 1–11. http://dx.doi.org/10.23880/ppej-16000339.
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Fines migration in reservoirs has a major impact on the oil industry, causing damage to formations due to micrometric particle mobilization and a consequent reduction in well productivity, thus resulting in significant economic damage. An emerging alternative for solving this problem is the use of nanofluids to mitigate fines migration. Due to their physicochemical properties, the mesoporous nanoparticles present in nanofluids interact with fines in the well, diminishing their mobility without an important decrease in permeability. In this work, the effect of a nanofluid composed of biogenic SiO2 mesoporous nanoparticles on fines migration control was studied. A biogenic mesoporous nanosilica was synthesized from rice husks and dispersed in a fluid composed of a mixture of diesel and xylene. Laboratory core-flooding experiments with crude oil were performed. The compositions of the crude oil and the collected material were measured to determine the changes in the crude oil after it interacted with the nanofluid. Fines production was significantly reduced by the use of the nanofluid. The results showed that 0.4% SiO2 nanoparticle fluid decreased fines migration by up to 60% with a small variation in permeability. The results of the GPC-ICP-HRMS analysis of the crude oil after treatment showed that the nanoparticles adsorbed a fraction of the asphaltenes in the crude oil and served as nucleation centers for the agglomeration of fines, forming larger structures with high porosity and allowing the fines to be retained in the core with a low decrease in permeability.
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KANG, SANG MOK y MYUNGHUN LEE. "An empirical study on effective pollution enforcement in Korea". Environment and Development Economics 9, n.º 3 (19 de mayo de 2004): 353–65. http://dx.doi.org/10.1017/s1355770x03001281.
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It has been recognized that extra incentives for firms' compliance with pollution regulations would be created under state-dependent enforcement as Harrington (1988) has shown theoretically. However, the extent of the overall improvement in compliance is expected to be different according to the pollution control costs and industrial structures of any given country. This paper empirically examines, for the first time, the effectiveness of an imposition of higher fines for repeated violations and state-dependent enforcement in terms of the reduction of violation days, by simulating emitting behavior for 65 sub-industries in the Korean manufacturing industry over the period 1987–1989. State-dependent enforcement was found to be more effective than an imposition of higher non-compliance fines for repeated violations in regard to the number of sub-industries exhibiting persistent non-compliance. However, the number of fully complying sub-industries was found to be slightly higher under an imposition of higher non-compliance fines for repeated violations. In Korea, it would therefore be desirable to discriminate against certain industries with enforcement systems of different intensity based on their abatement cost structures rather than uniformly introducing a state-dependent approach.
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Yang, Chau-Ping. "Composition of demolition wastes from Chi-Chi earthquake-damaged structures and the properties of their inert materials". Canadian Geotechnical Journal 46, n.º 4 (abril de 2009): 470–81. http://dx.doi.org/10.1139/t08-131.
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The disastrous Chi-Chi earthquake struck Taiwan on 21 September 1999 and resulted in the creation of more than 20 million cubic metres of demolition waste, which was stored temporarily at several sites. To reduce the site clearing costs, the inert materials (concrete, brick, pottery, and fines) in the wastes should be reclaimed and recycled immediately; but most of their properties were not known. Therefore, this study investigates the properties of demolition wastes, including inert materials, coarse portions, and fines obtained from two earthquake demolition waste storage sites (Puli and Tali) and one normal urban construction waste storage site (Taichung). It is found that the volumetric content of inert materials from earthquake demolition waste is about 96%. Such inert material is classified as having an excellent subgrade rating and can be reused as subbase and base soils. The abrasion level of the coarse portions of inert materials from the three sites meets the required level of coarse aggregate according to Standard Taiwan Code CNS-490. On the other hand, the maximum dry unit weights of fines of inert materials from the three sites are greater than 14.7 kN/m3, and their shear strengths are higher than that of the same classification group (SW–SM) of natural soils, so they can be reused as construction soils.
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Nicolas, Frédéric, Gabriel Montrieux y Aïcha Bourad. "La transition écologique à l’épreuve des sciences sociales du politique". Politix 144, n.º 4 (10 de junio de 2024): 9–35. http://dx.doi.org/10.3917/pox.144.0009.
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Face à la crise climatique, l’injonction à agir urgemment n’a jamais été aussi présente, mais contraste avec la forte inertie des politiques écologiques. Ce numéro de Politix prend le parti d’adopter une approche de sociologie générale et de sciences sociales du politique qui consiste à reconnaître la dimension particulièrement agonistique de la fabrique des politiques écologiques, tant dans l’espace social en général que dans les champs politique, bureaucratique et économique ou dans l’espace des mouvements sociaux et environnementaux. L’inertie des politiques écologiques est dès lors appréhendée à la fois comme le produit de structures sociales de domination et comme le vecteur de leur reproduction. Les groupes et acteurs sociaux qui occupent au sein de ces structures des positions dominantes sont parvenus non pas à rejeter les injonctions environnementales, mais à les rendre compatibles avec la préservation de leurs positions dominantes. Participant de différentes manières à la (re)définition et à la mise en œuvre de politiques écologiques, ces acteurs participent à dessiner les contours d’une question environnementale qui s’impose sans modifier en profondeur l’état des rapports sociaux.
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Mao, Wenting, Chunpeng Cao, Xincheng Li, Jueshi Qian y Yudong Dang. "An Experimental Investigation on the Effects of Limestone Fines in Manufactured Sands on the Performance of Magnesia Ammonium Phosphate Mortar". Buildings 12, n.º 2 (21 de febrero de 2022): 249. http://dx.doi.org/10.3390/buildings12020249.
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Magnesium ammonium phosphate cement (MAPC) prepared with ammonium dihydrogen phosphate (NH4H2PO4, ADP) and dead-burned Magnesium oxide (MgO) is a new type of rapid patch repair material for concrete structures. In order to reduce the material costs of MAPC mortar, manufactured limestone sands, being a more widely-available resource with lower cost, was investigated in this study as an alternative to quartz sands for the preparation of MAPC mortar. The limestone fines in manufactured sands were found to be the key factor that influences properties of MAPC mortar by causing bubbling and volume expansion before hardening. As a result, the mechanical strength of MAPC mortar decreased with the increasing content of limestone fines due to increased porosity. According to microstructure analysis, the mechanism of these negative effects can be inferred as the reaction between limestone fines and ADP with the gas generation of CO2 and NH3. This reaction mainly occurred during a short period before setting while most limestone fines remained unreactive in the hardened MAPC mortar. Based on the above detailed experimental findings on the effects of limestone fines in manufactured sand on the properties of MAPC mortar, this paper pointed out that effective defoaming methods for inhibiting bubbling was the key to the utilization of manufactured sands in preparation of high performance MAPC mortar.
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Nurminen, Ilkka, Erkki Saharinen y Jari Sirviö. "New technology for producing fibrillar fines directly from wood". BioResources 13, n.º 3 (15 de mayo de 2018): 5032–41. http://dx.doi.org/10.15376/biores.13.3.5032-5041.
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A method for producing lignocellulosic fibrillar fines directly from moist wood through a grinding process was evaluated. The method is based on a conventional stone wood grinding process with a novel grinding stone surface structure. The grinding stone (wheel) with a surface profile serrated in the axial direction of the wheel, forces fibres to break down into fibrils instead of detaching as fibres from the wood matrix. The arrangement mimics the inclined feeding of a log against a grinding stone and is completed without any related technical difficulties. Typically over a 90% conversion rate to fines (passing the Standard Mesh 200 wire) were achieved. The characteristics of the fines were influenced by the details of the surface structures, the velocity of the grinding stones, the feeding rate of the woods, and the specific energy consumption. This method enables novel means to adjusting the structure and properties of paper and paperboard products, as well as those of novel fibre and fibre-composite products.
Tesis sobre el tema "Préservation des structures fines"
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Longuefosse, Arthur. "Apprentissage profond pour la conversion d’IRM vers TDM en imagerie thoracique". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0489.
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L’imagerie thoracique présente des défis importants, chaque modalité d’imagerie ayant ses propres limitations. Le scanner (CT), référence en imagerie pulmonaire, offre une haute résolution spatiale, mais utilise des rayonnements ionisants, posant des risques pour les patients nécessitant des examens fréquents. À l’inverse, l’IRM pulmonaire offre une alternative sans radiation, mais est limitée par des problèmes techniques tels qu’un faible contraste et des artefacts, limitant son adoption clinique à grande échelle. Récemment, l’IRM à temps d’écho ultracourt (UTE-MRI) a montré un potentiel pour surmonter certaines de ces limitations, mais elle ne parvient toujours pas à atteindre la haute résolution et la qualité d’image du scanner, notamment pour l’évaluation détaillée des structures. L’objectif principal de cette thèse est de développer et valider des modèles basés sur l’apprentissage profond pour synthétiser des images de scanner TDM à partir d’IRM UTE. Plus précisément, nous visons à évaluer la qualité des images, la reconstruction anatomique et l’applicabilité clinique de ces images de synthèse par rapport aux IRM UTE originales et aux scanners CT correspondants. Dans un premier temps, nous avons exploré les bases de la synthèse d’images médicales, en établissant le socle pour la conversion de l’IRM vers le scanner. Nous avons mis en œuvre un modèle de GAN 2D basé sur le cadre pix2pixHD, optimisé avec la normalisation SPADE et affiné les techniques de prétraitement telles que le rééchantillonnage et l’enregistrement. L’évaluation clinique par des radiologues experts a montré des résultats prometteurs en comparant les images synthétiques aux scans réels. La synthèse a été ensuite améliorée par l’introduction de la perte perceptuelle, qui a affiné les détails structurels et la qualité visuelle, et par l’intégration de stratégies 2.5D pour équilibrer la synthèse 2D et 3D. De plus, nous avons mis l’accent sur un processus de validation rigoureux utilisant des métriques spécifiques à la tâche, remettant en question les métriques globales traditionnelles basées sur l’intensité, en nous concentrant sur la reconstruction précise des structures anatomiques. Dans la dernière étape, nous avons développé un cadre de synthèse 3D robuste et évolutif en adaptant nnU-Net pour la génération de scanner, accompagné d’une fonction de perte priorisant les caractéristiques anatomiques, permettant une meilleure reconstruction des structures critiques telles que les voies respiratoires et les vaisseaux. Notre travail met en évidence le potentiel des modèles basés sur l’apprentissage profond pour générer des images synthétiques de haute qualité de type scanner à partir d’IRM UTE, offrant une amélioration significative de l’imagerie pulmonaire non invasive. Ces avancées pourraient considérablement améliorer l’applicabilité clinique de l’IRM UTE, en offrant une alternative plus sûre au scanner pour le suivi des maladies pulmonaires chroniques. De plus, un brevet est actuellement en préparation pour l’adoption de notre méthode, ouvrant la voie à une utilisation potentielle en milieu cliniqueThoracic imaging faces significant challenges, with each imaging modality presenting its own limitations. CT, the gold standard for lung imaging, delivers high spatial resolution but relies on ionizing radiation, posing risks for patients requiring frequent scans. Conversely, lung MRI, offers a radiation-free alternative but is hindered by technical issues such as low contrast and artifacts, limiting its broader clinical use. Recently, UTE-MRI shows promise in addressing some of these limitations, but still lacks the high resolution and image quality of CT, particularly for detailed structural assessment. The primary objective of this thesis is to develop and validate deep learning-based models for synthesizing CT-like images from UTE-MRI. Specifically, we aim to assess the image quality, anatomical accuracy, and clinical applicability of these synthetic CT images in comparison to the original UTE-MRI and real CT scans in thoracic imaging. Initially, we explored the fundamentals of medical image synthesis, establishing the groundwork for MR to CT translation. We implemented a 2D GAN model based on the pix2pixHD framework, optimizing it using SPADE normalization and refining preprocessing techniques such as resampling and registration. Clinical evaluation with expert radiologists showed promising results in comparing synthetic images to real CT scans. Synthesis was further enhanced by introducing perceptual loss, which improved structural details and visual quality, and incorporated 2.5D strategies to balance between 2D and 3D synthesis. Additionally, we emphasized a rigorous validation process using task-specific metrics, challenging traditional intensity-based and global metrics by focusing on the accurate reconstruction of anatomical structures. In the final stage, we developed a robust and scalable 3D synthesis framework by adapting nnU-Net for CT generation, along with an anatomical feature-prioritized loss function, enabling superior reconstruction of critical structures such as airways and vessels. Our work highlights the potential of deep learning-based models for generating high-quality synthetic CT images from UTE-MRI, offering a significant improvement in non-invasive lung imaging. These advances could greatly enhance the clinical applicability of UTE-MRI, providing a safer alternative to CT for the follow-up of chronic lung diseases. Furthermore, a patent is currently in preparation for the adoption of our method, paving the way for potential clinical use
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Vicente, David. "Modèles de Mumford-Shah pour la détection de structures fines en image". Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2055/document.
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Cette thèse est une contribution au problème de détection de fines structures tubulaires dans une image2-D ou 3-D. Nous avons plus précisément en vue le cas des images angiographiques. Celles-ci étant bruitées, les vaisseaux ne se détachent pas nettement du reste de l’image, la question est donc de segmenter avec précision le réseau sanguin. Le cadre théorique de ce travail est le calcul des variations eten particulier l'énergie de Mumford-Shah. Cependant, ce modèle n'est adapté qu'à la détection de structures volumiques étendues dans toutes les directions de l’image. Le but de ce travail est donc deconstruire une énergie qui favorise les ensembles qui ne sont étendus que dans une seule direction, cequi est le cas de fins tubes. Pour cela, une nouvelle inconnue est introduite, une métrique Riemannienne,qui a pour but la détection de la structure géométrique de l’image. Une nouvelle formulation de l’énergie de Mumford-Shah est donnée avec cette nouvelle métrique. La preuve de l'existence d'une solution au problème de la minimisation de l’énergie est apportée. De plus, une approximation par gamma-convergence est démontrée, ce qui permet ensuite de proposer et de mettre en oeuvre une implémentation numériqueThis thesis is a contribution to the fine tubular structures detection problem in a 2-D or 3-D image. We arespecifically interested in the case of angiographic images. The vessels are surrounded by noise and thenthe question is to segment precisely the blood network. The theoretical framework of our work is thecalculus of variations and we focus on the Mumford-Shah energy. Initially, this model is adapted to thedetection of volumetric structures extended in all directions of the image. The aim of this study is to buildan energy that favors sets which are extended in one direction, which is the case of fine tubes. Then, weintroduce a new unknown, a Riemannian metric, which captures the geometric structure at each point ofthe image and we give a new formulation of the Mumford-Shah energy adapted to this metric. Thecomplete analysis of this model is done: we prove that the associated problem of minimization is wellposed and we introduce an approximation by gamma-convergence more suitable for numerics. Eventually,we propose numerical experimentations adapted to this approximation
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André, Raphaël. "Etude des structures fines de la convection ionospherique observees par superdarn : structures a forte divergence de vitesse". Orléans, 1997. http://www.theses.fr/1997ORLE2027.
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La chaine de radars a diffusion coherente superdarn observe dans les regions polaires, les mouvements de convection du plasma ionospherique qui sont induits par les interactions soleil-terre. Le premier objectif de ce travail est de mettre en place des outils permettant l'etude des structures fines se developpant dans la convection ionospherique. Deux themes complementaires sont developpes : - l'application d'une theorie de la diffusion collective permet d'extraire des parametres (temps de coherence, coefficient de diffusion) caracterisant la turbulence micro-echelle (l15 m) donnant naissance au signal enregistre par les radars. On utilise ces parametres pour separer differents regimes de turbulence, pour mettre en valeur des zones de transfert d'energie entre l'ionosphere et la magnetosphere. - la deuxieme direction consiste a mettre en place une methode d'analyse permettant de construire des cartes vectorielles de vitesses qui optimisent la resolution de base du radar (l45 km). Une telle methode doit faire face a des difficultes propres aux radars utilises, a savoir une localisation incertaine de la mesure, introduite par l'utilisation d'une onde haute frequence (hf), et une dependance des vecteurs entre eux due a la forme des volumes analyses. Ces problemes sont resolus par une etude detaillee sur la propagation des ondes hf et sur la localisation des mesures, puis par la mise en place d'une methode d'analyse spectrale haute resolution performante qui augmente la quantite d'information deduite d'une seule donnee radar. Cette methode de cartographie a haute resolution a permis de mettre en evidence dans les donnees superdarn, des structures caracterisees par une tres forte divergence des vitesses, qui sont en contradiction avec l'hypothese largement admise d'un mouvement sans divergence. L'ensemble des caracteristiques macro-echelles (45 km) et micro-echelles (15 m) de ces structures, conduit a une interpretation en termes de demagnetisation locale et temporaire des ions du plasma dans l'ionosphere aurorale. Cette etude se termine par la proposition de mecanismes capables de reproduire ces observations.
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Manoubi, Tahar. "Spectroscopie des pertes d'énergie des électrons sur quelques oxydes : analyse quantitative et structures fines". Paris 11, 1989. http://www.theses.fr/1989PA112267.
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Une grande gamme d'oxydes a été étudiée par spectroscopie des pertes d'énergie des électrons afin de relier les spectres d'excitations électroniques à la structure cristalline et à la composition chimique. Ce travail a été effectué avec un spectromètre magnétique de bonne résolution énergétique (moins de 1 eV sur toute la gamme des pertes de 0 à 2000 eV) sur un microscope électronique STEM permettant d'analyser des zones d'échantillons de quelques nm, ce qui est très important pour des milieux inhomogènes. Ce travail décrit: 1) Une méthode de microanalyse quantitative sur lames minces à partir de deux techniques permettant de mesurer des concentrations locales avec les signaux caractéristiques d'excitation d'orbitales atomiques. La première utilise la soustraction du fond continu sous le signal et nous avons estimé la précision et les sources d'erreurs. La seconde, entièrement originale, consiste à modéliser le spectre expérimental comme la superposition de diverses contributions que l'on sait calculer. Nous avons ainsi amélioré la détermination expérimentale des sections efficaces M45 des lanthanides. 2) Un outil de spectroscopie à haute résolution sur ces lames minces aussi bien pour les excitations des électrons de valence, que pour les seuils d'excitation d'orbitales atomiques. Dans le premier cas nous avons précisé la notion de plasmon dans ces composés fort différents du jellium et défini la population d'électrons associés à une transition identifiée. Dans le second cas, nous avons étudié les structures fines au seuil et près du seuil en fonction des paramètres comme la symétrie cristalline sur le site excité, ou la densité de charge locale. Le comportement spécifique du poids des raies blanches sur les seuils L23 des métaux de transition et M45 des métaux de terres rares a été analysé, et sur le seuil K de l'oxygène les effets de champ cristallin ont été séparés de ceux dus au remplissage partiel de la bande dA large family of oxides has been investigated by electron energy loss spectroscopy in order to correlate electron excitation spectra to crystal structure and chemical composition. This study has been performed with a magnetic spectrometer of high energy resolution (sub 1 eV over the loss range 0-2000 eV) and in a STEM with high spatial resolution (a few nm), which is quite suited to inhomogeneous specimens. This manuscript deals with two major developments. Lt describes: 1) A quantitative elemental analysis method on thin foils. Two approaches have been followed to extract local concentration measurements from the intensities of characteristic core edges. The first one uses subtraction of background fitted with a power law curve and we have evaluated the precision of the measurement and uncertainties sources. The second one consists in modelizing the experimental spectrum as the superposition of several computed contributions. We have thus improved the experimental determination of M45 cross sections for lanthanides. 2) A high resolution spectroscopy tool on thin foils, for both valence electrons and atomic orbitals excitations. In the first case, the concept of plasmon bas been discussed in these compounds which differ noticeably from the simple jellium, and the parameterization of the dielectric constants is used to define the electron population for a given excitation feature. Ln the second case, the fine structure on the threshold and in the vicinity of the absorption edges have been recorded for different site symmetries and local charge densities. The intensity of white lines on transition metal L23 edges and rare earth metal M45 edges has been analyzed. For oxygen K edges, the crystal field affect has been discriminated from the d band occupancy one
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Rolin, Raphaël. "Contribution à une démarche numérique intégrée pour la préservation des patrimoines bâtis". Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2450/document.
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Au travers de l’ensemble de ces travaux, l’objectif principal consiste à valider la pertinence de la construction et de l’utilisation de modèles 3D géométriques ou paramétriques orientés BIM/hBIM pour des analyses numériques. Il s’agit notamment d’études structurales dans le cas de bâtiments historiques ainsi que la planification potentielle de travaux de restauration, rénovation énergétique et réhabilitation. Des travaux d’exploitation complémentaires des données et des nuages de points, pour la détection, la segmentation et l’extraction d’entités géométriques ont également été intégrés dans les travaux et la méthodologie proposée. Le processus de traitement des données, modélisation géométrique ou paramétrique et leur exploitation, proposé dans ces travaux, contribue à améliorer et mieux comprendre les contraintes et enjeux des différentes configurations et conditions liées aux cas d’études et aux contraintes spécifiques propres aux types de constructions. Les contributions proposées pour les différentes méthodes de modélisation géométriques et paramétriques à partir des nuages de points, sont abordées par la construction de modèles géométriques orientés BIM ou hBIM. De même, les processus de détection d’éléments surfaciques et d’extraction de données à partir de nuages de points mis en place sont présentés. La mise en application de ces méthodes de modélisation est systématiquement illustrée par différents cas d’étude, dont l’ensemble des travaux relatifs ont été effectués dans le cadre de cette thèse. Le but est dès lors de démontrer l’intérêt et la pertinence de ces méthodes numériques en fonction du contexte, des besoins et des études envisagées, par exemple avec la flèche de la cathédrale de Senlis (Oise) et le site de l’Hermitage (Oise). Des analyses numériques de type éléments finis permettent ensuite de valider la pertinence de telles démarchesThroughout this work, the main objective is to validate the relevance of construction and use of geometric or parametric 3D models BIM or hBlM-oriented for numerical analyzes. These include structural studies in the case of historic buildings, as well as planning for restoration work, energy renovation and rehabilitation. Complementary data mining and use of point clouds for the detection, segmentation and extraction of geometric features have also been integrated into the work and proposed methodology. The process of data processing, geometric or parametric modeling and their exploitation, proposed in this work, contributes to improve and understand better the constraints and stakes of the different configurations and conditions related to the case studies and the specific constraints specific to the types of constructions. The contributions proposed for the different geometric and parametric modeling methods from point clouds are addressed by the construction of geometric models BIM or hBlM-oriented. Similarly, the process of surface detection, extraction of data and elements from point clouds are presented. The application of these modeling methods is systematically illustrated by different case studies, all of whose relative work has been carried out within the framework of this thesis. The goal is therefore to demonstrate the interest and relevance of these numerical methods according to the context, needs and studies envisaged, for example with the spire of the Senlis cathedral (Oise) and the Hermitage site (Oise). Numerical analyzes with finite element method are used to validate the relevance of these approaches
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Morard, Vincent. "Détection de structures fines par traitement d'images et apprentissage statistique : application au contrôle non destructif". Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00932727.
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Dans cette thèse, nous présentons de nouvelles méthodes de traitement d'images pourextraire ou rehausser les éléments fins d'une image. Pour ces opérateurs, issus de la morphologie mathématique,l'accent a été mis principalement sur la précision de détection et sur le temps de calcul,qui doivent être optimisés pour pouvoir répondre aux contraintes de temps imposées par différentesapplications industrielles. La première partie de ce mémoire présente ces méthodes, organisées enfonction de la tortuosité des objets à détecter. Nous commençons par proposer un algorithme rapidepour le calcul des ouvertures 1-D afin d'extraire des structures rectilignes des images. Puis, nous étudionsune nouvelle classe d'opérateurs rapides avec les ouvertures parcimonieuses par chemins, permettantd'analyser des structures ayant une tortuosité modérée. Enfin, nous proposons de nouveauxéléments structurants adaptatifs et des filtres connexes construits avec des attributs géodésiques etgéométriques pour extraire des structures filiformes ayant une tortuosité quelconque.Dans un second temps, nous avons développé une méthode d'analyse statistique en introduisantune nouvelle pénalisation adaptative. L'objectif consiste à créer un modèle prédictif précis, quiminimise en même temps une fonction de coût, indépendante des données. Lorsque cette fonctionde coût est liée au temps de calcul de chaque descripteur, il est alors possible de créer un modèleparcimonieux précis et qui minimise les temps de calcul. Cette méthode est une généralisation desrégressions linéaires et logistiques Ridge, Forward stagewise, Lar, ou Lasso.Les algorithmes développés dans cette thèse ont été utilisés pour trois applications industrielles,très différentes les unes des autres, mais toutes faisant intervenir une approche multidisciplinaire : letraitement d'images et l'analyse statistique. L'association de ces deux disciplines permet d'améliorerla généricité des stratégies proposées puisque les opérateurs de traitement d'images alliés à un apprentissagesupervisé ou non supervisé, permettent d'adapter le traitement à chaque application.Mots clés : Traitement d'images, morphologie mathématique, analyse statistique, caractérisation deformes, contrôles non destructifs, ouvertures parcimonieuses par chemins, region growing structuringelements, amincissements par attributs géodésiques et topologiques, adaptive coefficient shrinkage.
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Drogoul, Audric. "Méthode du gradient topologique pour la détection de contours et de structures fines en imagerie". Thesis, Nice, 2014. http://www.theses.fr/2014NICE4063/document.
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Cette thèse porte sur la méthode du gradient topologique appliquée au traitement d'images. Principalement, on s'intéresse à la détection d'objets assimilés, soit à des contours si l'intensité de l'image à travers la structure comporte un saut, soit à une structure fine (filaments et points en 2D) s'il n'y a pas de saut à travers la structure. On commence par généraliser la méthode du gradient topologique déjà utilisée en détection de contours pour des images dégradées par du bruit gaussien, à des modèles non linéaires adaptés à des images contaminées par un processus poissonnien ou du bruit de speckle et par différents types de flous. On présente également un modèle de restauration par diffusion anisotrope utilisant le gradient topologique pour un domaine fissuré. Un autre modèle basé sur une EDP elliptique linéaire utilisant un opérateur anisotrope préservant les contours est proposé. Ensuite, on présente et étudie un modèle de détection de structures fines utilisant la méthode du gradient topologique. Ce modèle repose sur l'étude de la sensibilité topologique d'une fonction coût utilisant les dérivées secondes d'une régularisation de l'image solution d'une EDP d'ordre 4 de type Kirchhoff. En particulier on explicite les gradients topologiques pour des domaines 2D fissurés ou perforés, et des domaines 3D fissurés. Plusieurs applications pour des images 2D et 3D, floutées et contaminées par du bruit gaussien, montrent la robustesse et la rapidité de la méthode. Enfin on généralise notre approche pour la détection de contours et de structures fines par l'étude de la sensibilité topologique d'une fonction coût utilisant les dérivées m−ième d'une régularisation de l'image dégradée, solution d'une EDP d'ordre 2mThis thesis deals with the topological gradient method applied in imaging. Particularly, we are interested in object detection. Objects can be assimilated either to edges if the intensity across the structure has a jump, or to fine structures (filaments and points in 2D) if there is no jump of intensity across the structure. We generalize the topological gradient method already used in edge detection for images contaminated by Gaussian noise, to quasi-linear models adapted to Poissonian or speckled images possibly blurred. As a by-product, a restoration model based on an anisotropic diffusion using the topological gradient is presented. We also present a model based on an elliptical linear PDE using an anisotropic differential operator preserving edges. After that, we study a variational model based on the topological gradient to detect fine structures. It consists in the study of the topological sensitivity of a cost function involving second order derivatives of a regularized version of the image solution of a PDE of Kirchhoff type. We compute the topological gradients associated to perforated and cracked 2D domains and to cracked 3D domains. Many applications performed on 2D and 3D blurred and Gaussian noisy images, show the robustness and the fastness of the method. An anisotropic restoration model preserving filaments in 2D is also given. Finally, we generalize our approach by the study of the topological sensitivity of a cost function involving the m − th derivatives of a regularization of the image solution of a 2m order PDE
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Payen, Julien. "Etude et développement de structures fibreuses nontissées dédiées à la filtration de particules fines dans l'air". Phd thesis, Université de Valenciennes et du Hainaut-Cambresis, 2009. http://tel.archives-ouvertes.fr/tel-00474263.
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Les médias fibreux nontissés sont des structures textiles très répandues dans le cadre de la filtration de l'air et plus particulièrement pour des particules fines de taille inférieure à 1 µm. Dans cette application, on recherche toujours un compromis entre l'efficacité de filtration (capture des particules) et la perte de charge (écoulement du fluide). Les caractéristiques structurelles des nontissés sont des facteurs primordiaux quant aux propriétés finales de filtration recherchées. L'approche est ici originale, car nous proposons de développer nos propres nontissés filtrants à l'aide d'outils de productions proches de l'industrie. Nous pouvons ainsi sélectionner des critères de structures (épaisseur, masse surfacique, type de fibres, diamètre des fibres etc.) adaptés aux propriétés de filtration de l'air que nous souhaitons étudier. Sur l'ensemble des caractéristiques structurelles étudiées nous avons montré que le paramètre le plus significatif sur les propriétés de filtration est le diamètre des fibres. Lorsqu'il diminue, nous augmentons l'efficacité mais au détriment de la perte de charge. L'expression de la longueur surfacique de fibres a été définie et est apparue comme un paramètre pertinent pour rendre compte des propriétés de filtration. Nous avons par ailleurs mis en évidence que la compacité augmentait fortement l'efficacité et la perte de charge. Notre étude sur des échantillons à base d'un mélange de diamètres de fibres montre que l'efficacité de filtration devait être assurée dans de tels mélanges par une longueur surfacique de fibres fines suffisante, alors que la quantité de fibres de diamètre plus élevé permet une structuration du média fibreux garantissant une perte de charge faible. La production de nanofibres par le procédé electrospinning nous a permis d'obtenir des échantillons avec des fibres de 250 nm de diamètre. L'amélioration du compromis efficacité/perte de charge observée est due à des nombres de Knudsen de fibres plus élevés que pour des échantillons microfibres. La modélisation des propriétés de filtration montre dans le cas d'échantillons idéalisés (fibres cylindriques, diamètre de l'ordre de 10 µm etc.) que la théorie est plutôt conforme avec les expérimentations. Cependant nous avons montré qu'en utilisant des mélanges de fibres ou des formes de section de fibres spéciales, ces modèles présentent certaines limites. Nous avons proposé des pistes avec notamment la prise en compte de nombreuses caractéristiques de la structure fibreuse afin d'obtenir des résultats plus proches des expérimentations.
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Cartier, dit Moulin Christophe. "Structures fines d'absorption des rayons X de complexes moléculaires d'éléments de transition de la premiere période". Paris 11, 1988. http://www.theses.fr/1988PA112002.
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Ce travail est consacré à l'étude par spectroscopie d'absorption des rayons X de complexes moléculaires d'éléments de transition de la première période. Une première partie porte sur l'étude fondamentale des structures fines au seuil d'absorption : nous utilisons la flexibilité de la chimie de coordination pour étudier des complexes de stéréochimie et de structure électronique variées. Pour des molécules discrètes de structure connue, nous mettons en évidence l'influence sur le seuil du degré d'oxydation et de l'état de spin de l'élément de transition, de la symétrie du site, des distances métal-ligand et des différentes couches de voisins. Nous interprétons les transitions vers des états liés dans une approche orbitale moléculaire. Dans le domaine d'énergie où le photoélectron est éjecté, nous utilisons l'approche "diffusion multiple". L'intérêt et les limites des deux modèles sont discutés. Enfin, la présence de bandes d'intensité faible est attribuée à des transitions biélectroniques. La compréhension de l'influence des différents paramètres électroniques et structuraux qui déterminent les structures fines du seuil, et l'analyse EXAFS, sont ensuite utilisées pour l'étude structurale et stéréochimique de matériaux nouveaux intéressants pour leurs propriétés physiques, chimiques et catalytiques. Nous avons ainsi caractérisé :- les modifications structurales associées aux transitions de spin dans des complexes du fer(ll), du fer(lll) et du cobalt(ll). - la stéréochimie de complexes du titane(IV), actifs dans l'oxydation de sulfures en sulfoxydes : à toutes les étapes de la réaction, les espèces sont octaédriques et ne présentent pas d'arrangement di -oxo. - l'ordre local dans les porphyrines de fer à anse de panier, modèles de l'hémoglobine. Le spectre de la forme oxygénée permet de proposer une formulation Fe(ll)-02 plutôt que Fe(lll)-02 -. L'EXAFS résolu dans le temps permet de réaliser des cinétiques structurales et a été utilisé pour étudier l'environnement de l'ion fer au cours de la réaction d'oxydation d'une porphyrine de fer(ll) à anse de panierLn this work, molecular complexes of the first period transition elements are studied by X-ray absorption spectroscopy. The first point is devoted to a fundamental study of the absorption edge: we take advantage of the versatility of coordination chemistry, to study complexes, with different stereochemistries and electronic structures. Ln the case of isolated molecules with well-known structures, we point out the influence of oxidation and spin states of the metallic ion, symmetry, metal-ligand distances and remote neighbours shells upon the edge. We discuss the transitions towards bound states using a molecular orbital approach. As for the XANES part of the spectrum, we use multiple scattering theory. We discuss the interest and the limitations of the two models. Sorne weak bands can be attributed to bielectronic transitions. This knowledge of the influence of different structural and electronic parameters which impel the fine structures of the edge and EXAFS spectroscopy are then used to characterise the local structure and stereochemistry of new compounds, of interest for their physical, chemical and catalytic properties. Then we studied:- The structural changes occurring during thermal spin cross-over in iron(ll), iron(lll) and cobalt(ll) complexes. - The stereochemistry of titanium(IV) complexes active in oxidation of sulfides in sulfoxides :at each reaction step, species are octahedral and do not show di µ oxo geometry. - The local order in basket-handle iron porphyrins, model compounds of haemoglobin. The spectrum of the oxy species allows to propose a Fe(ll)-02 formulation rather than a Fe(lll)-02 -. We used the time resolved EXAFS spectrometer at LURE to record structural kinetics data and study iron surroundings during the oxidation of an iron(ll) basket-handle porphyrin
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Cartier, dit Moulin Christophe. "Structures fines d'absorption des rayons X de complexes moléculaires d'éléments de transition de la première période". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37612490z.
Texto completoLibros sobre el tema "Préservation des structures fines"
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Pierre, Toubert, ed. Casas y casas principales urbanas: El espacio domésico de Toledo a fines de la Edad Media. [Toledo]: Ediciones de la Universidad de Castilla-La Mancha, 2004.
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Bordeaux. Direction générale de l'aménagement. Bordeaux et son agglomération, vers une métropole durable: Le pont Bacalan-Bastide, pour une préservation durable du port de la Lune, le plus grand site urbain du patrimoine mondial. Bordeaux: Éd. Overworld, 2009.
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Basurto, Gabriel Mérigo. El pasado es prólogo: Conservación del patrimonio universitario arquitectónico de México. 2a ed. Ciudad de México: Universidad Nacional Autónoma de México, Facultad de Arquitectura, 2020.
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Nondestructive Techniques for the Assessment and Preservation of Historic Structures. Taylor & Francis Group, 2017.
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Rodrigues, Hugo, Florindo Gaspar y Luisa Maria da Silva Gonçalves. Nondestructive Techniques for the Assessment and Preservation of Historic Structures. Taylor & Francis Group, 2017.
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Rodrigues, Hugo, Florindo Gaspar y Luisa Maria da Silva Gonçalves. Nondestructive Techniques for the Assessment and Preservation of Historic Structures. Taylor & Francis Group, 2017.
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Rodrigues, Hugo, Florindo Gaspar y Luisa Maria da Silva Gonçalves. Nondestructive Techniques for the Assessment and Preservation of Historic Structures. Taylor & Francis Group, 2017.
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The once and future New York: Historic preservation and the modern city. Minneapolis: University of Minnesota Press, 2009.
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Preserving New York: Winning the Right to Protect A City's Landmarks. Routledge, 2007.
Buscar texto completoCapítulos de libros sobre el tema "Préservation des structures fines"
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Alassal, Mohamed A., Asmaa M. Hassan y Hussein H. Elmamlouk. "Effect of Fines and Matric Suction on the Collapsibility of Sandy Soils". En Innovative Solutions for Deep Foundations and Retaining Structures, 61–72. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-34190-9_6.
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Singh, Davinder, Tarun Kumar y Amandeep Kaushal. "Influence of Fly ash, Lime, Fines Obtained From Demolished Structures Waste On Geotechnical and Strength Characteristics of Soil". En Lecture Notes in Civil Engineering, 327–34. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-51354-2_30.
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"4. Les structures fines des Saturnales". En Rhétorique et poétique de Macrobe dans les 'Saturnales', 107–55. Turnhout: Brepols Publishers, 2010. http://dx.doi.org/10.1484/m.rrr-eb.4.00545.
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Li, Junxia, Podianko Surya y En-Hua Yang. "Engineered cementitious composites incorporating recycled concrete fines". En From Materials to Structures: Advancement through Innovation, 1129–34. CRC Press, 2012. http://dx.doi.org/10.1201/b15320-201.
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Alberto-Hernandez Yolanda y Towhata Ikuo. "Undrained Response of Sand Containing Non-Plastic Fines". En From Fundamentals to Applications in Geotechnics. IOS Press, 2015. https://doi.org/10.3233/978-1-61499-603-3-3151.
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Current simplified procedures for estimating liquefaction resistance consider an increase in the measured SPT-N for sand containing fines. Nevertheless, it is not clear if this increase corresponds to an increase in resistance or to a decrease in penetration resistance due to fines compressibility. To date, several researchers have studied in laboratory the influence of non-plastic fines on the liquefaction resistance of sands considering different approaches in which they keep constant a density index for comparison such as void ratio, relative density, sand-skeleton void ratio or inter-granular void ratio, equivalent void ratio and inter-fine void ratio. This has led to divergent conclusions that will be described and explained in this paper. The interest in this topic has increased after the recent events of liquefaction in Taiwan, New Zealand or Tokyo, where liquefaction caused significant damage to buildings, houses, retaining structures and underground infrastructure. Sand retrieved from Tokyo Bay was studied in this research. A hollow cylindrical torsional shear apparatus was used to conduct a series of tests to determine the effect of non-plastic fines on the liquefaction potential of sand. Given the disagreement of the role of non-plastic fines in previous researches, it was decided to test samples at the same SPT N-value. The coefficient of volume compressibility, mv, was selected for comparison as it is inversely related to the SPT N-value. Samples were consolidated at the same mvvalue and then sheared under monotonic and cyclic loading. Later, the volumetric strain after liquefaction was also measured and results are presented herein and discussed. Relevant conclusions regarding the role of non-plastic fines on the undrained behavior of sands, are provided.
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Chen Mengjia y Wong Yiik Diew. "Investigating the packing condition of porous asphalt mixture using Discrete Element Method". En Construction Materials and Structures. IOS Press, 2014. https://doi.org/10.3233/978-1-61499-466-4-629.
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Packing condition is an important factor to asphalt mixture's capacity in carrying traffic loads and resisting deformation, which is directly dependent on aggregate gradation. Porous Asphalt Mixture (PAM), with a characteristic feature of open-graded design, is advantageous in improving drainage, lowering noise level, and generating cooling effect, making it an appropriate material for a tropical country like Singapore. However, current gradation design methods are mostly based on dense asphalt mixtures, and little research has been conducted in providing explicit and direct parameters to represent the packing condition in a mixture. In this study, six PAMs were designed and relevant parameters were obtained from both laboratory experiments and Discrete Element Method (DEM) simulation. From four types of DEM models for each PAM group, it was found that particle-to-particle interlocking among coarser particles is affected by both size and amount of finer particles. In essence, DEM simulations showed that the development of packing condition among an assembly of particles is not only related to the percentage of fines fraction, but also the proportions of particles within various size ranges, and this finding corroborated with laboratory measurements of air voids content in the PAMs. This study indicates that DEM is an effective tool in analysing the packing condition in a mixture, and the findings should be a useful guide in PAM gradation design.
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Rangoni, Bernardo. "Experimentalist Architectures, Processes, and Outcomes". En Experimentalist Governance, 38–75. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780198849919.003.0003.
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Abstract This chapter analyses how and why experimentalist structures—notably the Florence Forum—were used extensively to regulate European electricity market integration (namely, network access and tarification) from the late 1990s to the present date. It shows that far from gradually declining, experimentalist processes persisted across multiple policy cycles. It argues that functional and legal as well as political factors—specifically, steadily multipolar distributions of power and recurring uncertainty as well as opposition—placed major pressures on key actors to use experimentalist structures actively and continuously. To deliver policy outcomes effectively despite the notoriously well-entrenched interests characterizing the domain, experimentalist governance did not exclusively rely on any single mechanism. Instead, its carriers threatened the imposition of both specific positive rules—as distinctive of the shadow of hierarchy—and negative prohibitions and fines—as characteristic of penalty defaults.
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Ralf, Sauer y Kellerbauer Manuel. "Part I Antitrust Rules (Articles 101 and 102 TFEU), 11 Infringement Decisions and Penalties". En EU Competition Procedure. Oxford University Press, 2022. http://dx.doi.org/10.1093/law-ocl/9780198799412.003.0011.
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This chapter discusses infringement decisions and penalties. There is no specific requirement for the European Commission as to the way in which it structures competition decisions, but they must meet the requirements contained in Article 296 of the Treaty on the Functioning of the European Union (TFEU). The basic layout of decisions applying Articles 101 and 102 TFEU consists of (i) a title; (ii) a preamble referencing the legal basis; (iii) recitals that contain a summary of the various procedural steps, an account of the facts, a legal assessment of those facts, as well as, where applicable, an explanation of the level of any sanctions (fines, penalty payments); and (iv) the Articles of the decision, known as the operative part or simply the ‘decision’. The operative part sets out the finding of an infringement and its duration for specific addressees (legal entities), the remedies required by the Commission, the amounts of any sanctions with arrangements for their payment, and an indication that the decision shall be enforceable pursuant to Article 299 TFEU. The chapter then focuses on infringement decisions, with particular attention paid to the operative part. This also includes declaratory decisions, orders to bring an infringement to an end and the imposition of remedies, as well as fines and periodic penalty payments imposed on undertakings for infringements of the substantive provisions of Articles 101 and 102 TFEU.
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Briki, Lyamine, Belkacem Benzeroual y Kamel Zidani. "Contribution to Improving the Rheological and Mechanical Performance of Sand Concretes Intended for Hydraulic Structures". En Advances in Transdisciplinary Engineering. IOS Press, 2024. https://doi.org/10.3233/atde241030.
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Some finely ground cement additives, such as slag, pozzolan and limestone, have a more or less marked influence on the physical, mechanical and chemical characteristics of concrete. With this in mind, the approach recommended in this study is to develop an economically reliable concrete, by completely replacing the construction sand with another sand dosed by the addition of 18% of 0/80µm limestone fillers. This sand is obtained by demolding residual waste from granular products. The study focused on the mechanical characterization of the new concrete, namely its strength, durability, impermeability and its ability to resist any aggression, while proposing a new matrix [concrete – fluntkut (bituminous emulation)]. Its objective is to valorize waste in terms of industrial fines accumulated in huge quantities at the level of quarries in Algeria. The results acquired have shown that the concretes made are very well responded to the addition of limestone fillers and reinforce their good resistance to ordinary OPC concrete. This reconstituted concrete sand has acquired a strong presence of calcium carbonate (CaCO3) which allows it to react easily with the silica SiO2 contained in the cement.
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Rangoni, Bernardo. "Common Architectures, Diverse Processes, and Trajectories". En Experimentalist Governance, 76–110. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780198849919.003.0004.
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Abstract This chapter shows that to regulate the integration of European gas markets from the late 1990s to the present date, common experimentalist structures—notably the Madrid Forum—were used to a different extent across different issue areas, namely, less in network access than in tarification. Further, it highlights that in the two issues, experimentalism followed diverse trajectories, gradually declining in the former while persisting in the latter. Distributions of legal power, which were identically multipolar, cannot explain this variation in processes and trajectories. Instead, the chapter emphasizes the explanatory value of functional and political factors, which, moreover, were far from antithetical to one another. In network tarification, re-emerging uncertainty and opposition placed major pressures to use experimentalist structures steadily. In network access, by contrast, by the mid-2000s, the European Commission had become convinced that it knew the best rules already and, thanks to the support of the Austrian and German authorities, could impose such rules on other recalcitrant actors. In the attempt to overcome gridlock, finally, the Commission threatened to impose both specific positive rules—as distinctive of the shadow of hierarchy—and negative prohibitions and fines—as characteristic of penalty defaults—instead.
Actas de conferencias sobre el tema "Préservation des structures fines"
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Isogai, Akira. "Factors Influencing on Retention of Alkylketene Dimer". En The Fundamentals of Papermaking Materials, editado por C. F. Baker. Fundamental Research Committee (FRC), Manchester, 1997. http://dx.doi.org/10.15376/frc.1997.2.1047.
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Mechanisms of retention of AKD are studied in terms of effects of cationic polymer additions, and roles of fines and carboxyl groups of pulp fibers. Handsheets were prepared from normal pulp and fines-free pulp under various conditions, and AKD contents in the handsheets were determined by pyrolysis-gas chromatography (PY-GC). The addition of cationic polymer (PAE) to pulp suspension was clearly effective in promoting AKD sizing for both cured and noncured handsheets, resulting from higher retention of AKD in the sheet by cationic PAE molecules. Potential measurement indicated that the originally cationic AKD emulsions come to have amphoteric surface charges in pulp suspension. The effective AKD retention by PAE may, therefore, be due to ionic bond formation between anionic sites of AKD emulsion surfaces and anionic pulp fibers or fines through cationic PAE molecules. The experiments using fines-free pulp showed that most of the added AKD was adsorbed on fines of beaten pulp. Blocking of carboxyl groups in pulp with nonionic methylamide groups resulted in nearly no sizing degrees and quite low AKD contents. Therefore, it is clear that dissociated carboxyl groups in pulp fibers and fines are the actual retention sites of AKD emulsion particles at the usual addition levels of AM Among chitosan salts and PAE used at 0.1-0.4 addition levels, chitosan AcOH salt gave the highest effect on AKD retention as well as sizing degrees. Good correlation between AKD contents and sizing degrees was obtained ; sizing behavior of AKD-sized handsheets was explainable in terms of their AKD contents determined by PY-GC, and thus retention of AKD is the significant first step for AKD sizing. Solid-state ,3C-NMR analysis of cellulase-treated residues of 13C-labelled AKD-sized handsheets showed that size components were present in papersheet as structures of either the original AKD or ketones, hydrolyzed AKD, without forming ß-ketoesters. SEM observations of AKD-sized handsheets indicated that the effect of curing on AKD sizing is explained in terms of melting of size molecules and their spreading over pulp fiber surfaces.
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Li, Wanru y George Hazelrigg. "The Potential for Incentive Structures to Prevent Significant Engineering Failures". En ASME 2023 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/detc2023-116706.
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Abstract All complex designs emerge as the result of the decisions made by the design engineers. It can be shown that the designs are best when the preferences guiding the engineering decisions align with the overall system or corporate preference. But we know that all people make decisions based on their own personal preferences, which are unlikely to align well with the corporate preference. This research addresses the question, what mechanisms can be used to better align engineers’ decisions to the system or corporate preference, but particularly such that major catastrophes might be prevented? Inspiration for this work comes from a number of very substantial losses that likely would have been prevented by the systems engineers had they the incentive to come forth with knowledge they certainly had. Examples include Boeing’s experience with the 737MAX, which appears to be costing Boeing more than $100 billion, and Volkswagen’s experience with the falsified emission testing of their diesel-engine vehicles, which resulted in over 31 billion euros in fines, penalties and other direct costs. We believe that incentive mechanisms could have been in place that would have prevented these very significant losses. Thus, we believe that there exist potential mechanisms that would benefit both the corporation and the engineers. We further believe that these mechanisms would not only improve corporate profitability but they have the potential to save many lives as well.
3
Gribulis, Domas, Gintaras Žaržojus, Saulius Gadeikis, Sonata Gadeikytė y Donatas Urbaitis. "Research of undrained shear strength of till fine soils (moraine)". En The 13th international scientific conference “Modern Building Materials, Structures and Techniques”. Vilnius Gediminas Technical University, 2019. http://dx.doi.org/10.3846/mbmst.2019.040.
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The undrained soil strength is specific to fine soils or to sands with a lot of fines. It is very important characteristic and the evaluation of accurate value is significant step. The undrained soil shear strength can be estimated directly in laboratory and indirectly in field using in-situ methods. The values of undrained shear strength estimated with different methods usually are different, sometimes very much. In geotechnical practice a lot of empirical equations are used to calculate undrained shear strength (cu), however it corrects only in specific conditions and can’t be used universally. The empirical factor (Nk), which is used in mentioned equations, varies in wide range. It depends on many factors. The research of glacial genesis fine soils (various moraines) is complicated because it specific grain size distributions and genesis. In this article we will study relation between different laboratory and field methods to estimate of undrained shear strength (cu) of till soils. For these purposes we will used upper Pleistocene, upper Nemunas formation till fine soils.
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Dodson, C. T. J. y W. W. Sampson. "A Model for the Retention of Particles in Evolving Fibre Networks". En The Fundamentals of Papermaking Materials, editado por C. F. Baker. Fundamental Research Committee (FRC), Manchester, 1997. http://dx.doi.org/10.15376/frc.1997.2.1161.
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A model is presented for the entrapment of a distribution of particles by a distribution of pores. The fraction of particles retained and their distribution of sizes can be calculated for evolving and static porous structures. For evolving structures the change in distribution and fractional retention through the structure can be calculated. Also, the variance in these parameters between zones in the plane of the sheet can be calculated. The agreement between the theory and experimental data is good . The theory has relevance to the retention of fillers and fines in the papermaking process and to more general problems of stochastic porous media.
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Zeinali, Hossein, Peter Toma y Ergun Kuru. "Near-Wall Turbulent Transport Knowledge for Suitable Flow Assurance Strategies". En ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79996.
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Gas-liquid transportation from the deep ocean floor level to wellhead and, then, to platforms and land processing units is often impeded by wax and hydrates deposits; sand erosion and corrosion-related being frequently encountered. During the last decades it was shown that apparently different problems such as sand erosion and deposition-removal of paraffin during turbulent pipe transportation are the effect of near-wall flow transport related to burst-sweep specific turbulent activity. Coherent structures visualized as a sequence of (in) bursts and outburst sweep actions has already been suggested as an important factor for understanding aging of the paraffin deposit and the deposition-removal balance controlling the grow of deposit. This paper, using published models, investigates the effect of near-wall turbulence on removal of small-size particulate matter, first through direct measurement of burst activity, then, using fine sand and glass beads transported as moving bed during turbulent flow condition. Lack of experimental data for assessing the effect of turbulent liquid pipe flow on burst activity for removal of fines created challenging problems. Those include direct assessment of burst frequency and measurement of the rate of fine sand grading and on-line sampling and measuring the rate of fine removal during sand bed or lenticular deposits transportation. Laboratory work uses a Particle Image Velocimetry (PIV) instrument to observe and quantified the burst activity as it progresses from the pipe wall to the turbulent core flow. Experimental data are closely compared to existing literature models; in addition the present laboratory measurements allow for describing the dynamic of a burst as it evolves from the pipe wall to turbulent core regions. The frequency of burst removal is further compared with changing of size distribution during the sand bed-slurry transport stage of this work. Results obtained so far at the University of Alberta with the aid of an experimental loop designed and operated for observing and quantifying selective (size-density) radial-axial transportation of fines are discussed and summarized. It is suggested that the experimental data on fines removal and deposition, particularly related to near-turbulent structure activity, is important for understanding and mitigating a broad range of near-wall turbulent-related flow assurance problems.
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Shajarati, A. y P. Knight. "In-Situ Strength Profiling Micaceous Sands for Offshore Foundation Design". En Innovative Geotechnologies for Energy Transition. Society for Underwater Technology, 2023. http://dx.doi.org/10.3723/efwo6042.
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This article presents an alternative procedure for in-situ strength profiling the supporting soil volume of offshore foundation structures. A particular focus is placed on coarse-grained materials with large fines and mica content. Soil types which are generally encountered offshore in South-East Asia and North America. The in-situ strength properties of such soils are challenging to evaluate using existing methodologies such as in-situ relative density relations. As an alternative procedure, it is suggested to calibrate the correlation between the in-situ properties and laboratory strength measurements based on the shear wave propagation velocity. Utilising this procedure decreases the statistical spread and uncertainties related to material property determination while a greater correlation can be made with the 3D geophysical ground model allowing for position-specific profiling without cone penetration data.
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Kukowski, Rob. "MDT: Micro Deformation Technology". En ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-42861.
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Micro-Deformation Technology (MDT) is a proprietary material deformation process that was originally developed for the production of engineered heat transfer tubing. The patented process employs a fixed tool, which mechanically and plastically deforms the work piece to form finite and repeatable channels. These channels are developed in one continuous pass or multiple passes of the tool and the geometric shape and angle of the tool define the final channeled form. The MDT process can achieve a variety of channles form. The MDT process can achieve a variety of channel depths, channel widths, fin shapes and angularity. It can be applied to rounds, sheet and contoured work pieces. MDT is readily adaptable to conventional machining and milling equipment. The MDT process can be performed on nearly any ductile material. Materials ranging from titanium, stainless steel, silver, aluminum, copper, to the non-metallic materials like Teflon, polyethylene, rubber and PVC have been successfully processed. Most materials can be channeled in excess of 250 channels/inch. The process generates no material fines and lubrication is not required for most applications. MDT is therefore ideal for precious metal conversion and secondary cleaning steps are generally not required. Channeling sheet from opposite sides, MDT is capable of producing fine meshes via the intersection of the angled channel depths. The repeatable and uniform channels produce an extremely uniform pore distribution from a solid body. The unique attributes of MDT make it an enabling technology. By itself or in combination with current processes, it opens capability that previously did not exist. Potential applications include: filters and screens; catalyst substrates; heat transfer; material flow and separation; heat pipes; surface cladding and adhesion; capillary structures; surface preparation; and solid surface lubrication, to name only a few.
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Avramenko, Valentin, Svetlana Bratskaya, Veniamin Zheleznov, Irina Sheveleva, Dmitry Marinin y Valentin Sergienko. "Latex Particles Functionalized With Transition Metals Ferrocyanides for Cesium Uptake and Decontamination of Solid Bulk Materials". En ASME 2010 13th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2010. http://dx.doi.org/10.1115/icem2010-40302.
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Decontamination of spent ion-exchange resins, corrosion-unstable metal structures, soil, ground, and construction materials contaminated by fission, corrosion and transuranic radionuclides remains one of the most urgent and complicated ecological problems. Among the existing methods having different efficiencies in regard to such materials decontamination, application of selective sorbents put into a humid medium to be decontaminated (ground, bulk materials) appears to be rather extensive. However, the efficiency of such an approach is significantly limited by difficulties concerned with uniform sorbent distribution in porous media and completeness of spent sorbents removal for final disposal. In this paper we suggest a principally new approach to preparation of colloid-stable selective sorbents for cesium uptake using immobilization of transition metals (cobalt, nickel, and copper) ferrocyanides in nanosized carboxylic latex emulsions. The effects of ferrocyanide composition, pH, and media salinity on the sorption properties of the colloid-stable sorbents toward cesium ions were studied in solutions containing up to 200 g/1 sodium nitrate or potassium chloride. The sorption capacities of the colloid sorbents based on mixed potassium/transition metals ferrocyanides were in the range 1.45–1.86 mol Cs/mol ferrocyanide with the highest value found for the copper ferrocyanide. It was shown that the obtained colloid-stable sorbents were capable to penetrate through bulk materials without filtration that makes them applicable for decontamination of solids, e.g. soils, zeolites, spent ion-exchange resins contaminated with cesium radionuclides. After decontamination of liquid or solid radioactive wastes the colloid-stable sorbents can be easily separated from solutions by precipitation with cationic flocculants providing localization of radionuclides in a small volume of the precipitates formed. Besides, functionalized latex particles can be used for preparation of carbon fiber/ferrocyanide composite materials for cesium uptake using electrodeposition method. Application of the carbon fibers as an inert support for ferrocyanides, in general, significantly improves the sorption kinetics, but washing out of ferrocyanide fines from the fiber surface limits the potential of such materials. When ferrocyanides are deposited in a form of nanocrystals stabilized by latexes which undergo electropolymerization on the fiber surface, the thin polymeric film formed substantially improves the stability of the composite and prevents loss of ferrocyanide during sorbent application. The effect of electrodeposition conditions on composite morphology, ferrocyanide loading and cesium distribution coefficient in media with different salinity has been discussed.
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Cottingham, Byron, Charles Landis, Ph.D., Josh Jordan y Chad Hall. "A Case Study of Enhancing Reservoir Performance Through Protecting the Matrix". En SPE International Conference and Exhibition on Formation Damage Control. SPE, 2024. http://dx.doi.org/10.2118/217874-ms.
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Abstract The North American oil and gas industry continues to focus on smaller pore space and there is a continued need to protect and enhance the pore space and fracture networks in our reservoirs. To achieve this, our team has developed and tested a new category of bio-based embedment control fluid additives, that has shown to directly improve reservoir performance after flowback by slowing the reduction of fracture conductivity in hydraulically fractured rock. Unconventional reservoirs are mineralogically complex. There is an array of minerals that are sensitive to invading waters including 2:1 layer silicates; "clays", oxides, substituted carbonates and freshly fractured silicates like quartz and feldspars. In North America, the clay fraction of the major plays is largely barren of discrete smectite, thus common clay control additives or the use of produced water brines for this purpose is poorly justified, and in fact promotes sloughing of the finest fractions from the fracture face (Landis et. al, 2018). In addition to fracture face softening, fines generation is a pronounced risk factor in reservoir damage mechanism especially with the use of common clay control additives. To address this problem in our industry, the team functionalized bio-based polymers to maximize polydentate encapsulation of fluid sensitive minerals on the fracture face. This interaction is exploited to reduce reservoir damage in the crucial early stages of the stimulation process. Molecular design, regain permeability testing and, finally, controlled field applications of the embedment control additive are shown in this paper to provide new realized value in the first year of production and beyond. The new bio-based additive differs from other higher molecular weight polymers used in the stimulation process. Smaller linear molecules functionalized with inhibitive substituents that do not exchange with the cations or anions in the mineral structures. When compared the larger polymers used for friction reduction, the targeted approach for the most interactive sites along the fracture face are addressed preferentially. A more direct indicator of embedment control is obtained with regain permeability analyses. Assessment of the new bio-based product was conducted on Wolfcamp landing zone facies, and the Eagle Ford formation targets. All tests were run at representative confining pressures and temperatures, and against KCl baselines. A case study was performed in the field and highlighted the product's capability with both a reduction in turbidity during flowback by 350%, and production enhancement of the wells performance indicating the potential of increased performance with proper reservoir protection. In summary, this paper highlights the need for reservoir protection, a novel approach to minimize formation damage, and both laboratory and field testing of the process to prove the performance enhancement of minimizing formation damage.
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Schaposnik, Viviana, Cecilia Giusso y Andrea Ulacia. "Autopistas y situaciones intersticiales urbanas: el valor del análisis-diagnóstico previo como instrumento de gestión e intervención". En International Conference Virtual City and Territory. Barcelona: Centre de Política de Sòl i Valoracions, 2009. http://dx.doi.org/10.5821/ctv.7567.
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Introducción: La consolidación del desarrollo urbano es asociada a la movilidad, en mayor medida si se trata de AUTOPISTAS. Involucrando lógicas propias y autónomas, resultan funcionales exclusivamente a sus fines: contener y conducir de modo eficiente el flujo vehicular, partiendo de imponer sus también propios condicionamientos espaciales -estructuras de soporte, intercambiadores, organizadores bajo, sobre y a nivel, puentes, túneles, pantallas visuales, entre otros-. Queda afectado entonces el sector del territorio sobre el que descienden, por una secuencia dominantemente lineal de distintas categorías de impactos, vinculados además al nivel de consolidación urbana.
Como producto de la interacción entre Fijos y Flujos -TERRITORIO/ AUTOPISTAS-, es que surgen las Situaciones Intersticiales urbanas, encaradas aquí desde un origen investigativo en donde el Intersticio fue entendido como diferencia entre entidades territoriales anteriores y nuevas superpuestas, redundante en hibridación material o funcional de respectivas condiciones originales, y abordado como producto de acciones y relaciones sociales, temporales y espaciales. Este espacio intersticial, fue considerado entonces información ineludible al abordar operaciones sobre áreas urbanas en correlato con flujos de movilidad autopistas.
Objetivos: Se pretende generar un corpus de inferencias conducente a la elaboración de futuros diagnósticos, pautas y estrategias, a fin de “mitigar” los impactos afectantes e irresueltos que producen la sumatoria de situaciones intersticiales y remanentes espaciales, para ser eficientemente incorporados como variables a tomar en cuenta en los estudios del territorio en tanto urbano.
Metodología: Los datos emergen de la aplicación de un instrumento de lectura e interpretación sistémica que atiende a la complejidad del tejido urbano y la superposición de estratos físicos y fenomenológicos: Herramienta Intersticio, en situaciones intersticiales “bajo autopista” en un recorte de Región Metropolitana de Buenos Aires/ RMBA – Argentina.
Conclusiones: Conclusiones genéricas producto del análisis, evidencian que el Flujo Autopista-AU corta/secciona a la CIUDAD, aceptado como hecho consumado su implantación y descenso en aras de la conectividad del territorio. Los DETERMINANTES ESPACIALES (modulación, soporte, senda-techo entre otros) condicionan las apropiaciones de manera tal que sea cual fuere el carácter del ámbito de inserción, contexto y autopista establecen un vínculo que–rozando en algunos casos la indiferencia-, no incita a contexto y autopista establecen un vínculo que–rozando en algunos casos la indiferencia-, no incita a “pleitos” urbanos verificables… Una adecuación (voluntaria?) que no evita que programa y usos predominantes, incidan desde este status quo en la dinámica del sitio… Aunque en muchos casos no difieran de los propios del sector de pertenencia, domina el conflicto en el escenario y su función de uso, situación que no ocurre cuando el mismo uso tiene una pertenencia al tejido urbano de la ciudad: es que la Autopista deja en su abajo, una suerte de confusión entre lo público y lo privado, que sumada a la
incidencia de estructura de soporte y plano superior límite, hacen que se produzcan siempre indefiniciones y/o conflictos -problemas propios de las infraestructuras en el territorio cuando no poseen
diagnósticos desde la gestión de pertenencia-.
Afrontar específicamente la evaluación de las condiciones de habitabilidad de las situaciones intersticiales estudiadas y/o la determinación de casos pasibles de una optimización -reconfiguración de la situación
presente-, conducen a reconocer la necesidad de una proyección del “sobre” y “bajo” autopista de manera conjunta.
Sumado a lo anterior, se confirma como necesaria la planificación previa de los intersticios “bajo autopista”, apoyada en el estudio realizado en esta investigación, desde una potencialidad espacial
latente y mal aprovechada, así como desde la anarquía evidente que los distintos usos-programas encontrados en esos espacios de muestra, en general con calidad urbana degradada. El ineludible vínculo entre el desarrollo urbano y la movilidad, deberá contar con instrumentos propios que contemplen estos espacios, no como remanente de una intervención, sino de manera sostenible, compatible con la
preservación y mejora del medioambiente natural y urbano, contribuyendo por las actividades que induce, directa e indirectamente en la formación de capital social. Introduction: Urban consolidation development is associated to motility, in great part if is referred to HIGHWAYS. Involving own and autonomy logics, they results functionality exclusively to its purpose: to content and conduce in an efficient way vehicular fluxes, starting from impose its own spatial conditions -
support structures, organizing under and upper level of bridges panels, tunnels, visuals screens, and so on-. The territorial sector where it happens this descending is affected because of a domineerig lineal
sequence of different categories of impacts entailed besides to urban consolidation level.
As a product of interaction between Fix and Fluxes -TERRITORY/ HIHGWAYS-, is that appears urban Interstitials Situations, faced here from an investigative origin where Interstice was understood as the
difference between previous territorial entities and new ones superposed, redounding in material or functional hybridization of respective original conditions, and boarded as a product of social, and spatial
actions and relations. So, this interstitial space, was considered unavoidable information when boarding operations over urban areas in relation with motility fluxes highways.
Objectives: The research, presently in development pretends to fix regulations and strategies appointing to a systematically formulation of typological patterns taking in account interstitially space, unavoidable
information to face actions over urban areas in relation with motility high-way fluxes and appropriation in the under high-way.
Methodologies: Is based in data emerging from the application of a reading and systemic interpretation instrument appointing to the complexity of urban tissue and the superposition of physics and phenomenological layers, -Interstitial Tool-, in interstitials situations “under highway” in a fragment of the Buenos Aires Metropolitan Region / RMBA – Argentina. By other way, digital descriptions are used as the best choice for representing all this process –still unfinished-, by the application of digital methods to board
the understanding of the mentioned urban problematic.
Conclusions: Generic conclusions as result of the analysis, put in evidence that the motility high-way fluxes cuts/sections the CITY, accepted its implantation and descent as a consummated fact in account of
territorial connectivity. SPATIAL DETERMINING (modulation, support, way-cover between others), conditions appropriations in that way, that it doesn’t matter character of the insertion contour; context and highway establishes a nexus; an urban adequation (voluntary or involuntary) that cannot avoid that programs and uses doesn’t fall into a sort of accepted status quo, even if in much cases have no difference from proper uses of the insertion area; conflict takes possession of the scene and its uses, all that because the highway leaves in its “under” a sort of confusion between public and privat activities,
adding to this, the incidence of the supporting structure and upper plane that conduces always to not resulted conditions and/or conflicts proper from this kind of infrastructures over territories when there isn’t governmental diagnostics and actions-.
The evaluation of specific conditions of habitability of the interstitial situations mentioned, must be boarded to be changed, as well as those cases apt to be optimized, producing a reconfiguration of present
situation. There is a responsibility about a simultaneous design of the upper and under highways. The unavoidable bond between urban development and motility must depend on, own instruments that overview those spaces , not as remnants of another intervention but in a sustainability way, compatible with preservation and an natural and urban ambient improvement, contributing to all that makes direct or indirectly to construct the social capital of urban areas.
Informes sobre el tema "Préservation des structures fines"
1
Lucker, Samantha y Bryant Robbins. Influence of fines content on the progression of backward erosion piping. Engineer Research and Development Center (U.S.), octubre de 2024. http://dx.doi.org/10.21079/11681/49445.
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Backward erosion piping is a form of internal erosion that endangers the structural stability of levees and dams. Understanding the factors that influence this form of erosion can result in improved risk assessment and more appropriate modifications to new and existing structures. Historically, it has been assumed that the presence of silt size particles would reduce the gradient required for erosion. This study investigated the influence of fines content on backward erosion piping through a series of laboratory experiments on silty sands. Laboratory results show that as the fines content increased in the samples, so too did the gradient required to produce and progress piping to failure. The results indicate that a new factor is needed to properly account for silt content in backward erosion piping (BEP) risk assessment of silty sands.
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Langlais, Pierre-Carl. Accès diamant. Comité pour la science ouverte, 2024. https://doi.org/10.52949/78.
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Contrairement à une idée répandue selon laquelle les publications en libre accès sont payées par leurs auteurs, de nombreux articles scientifiques sont diffusés sans frais pour les lecteurs et les auteurs (modèle « diamant »). En 2021, on estimait entre 17 000 et 29 000 le nombre de revues scientifiques reposant sur le modèle diamant. Les revues accessibles gratuitement représentaient 73 % des revues enregistrées dans le DOAJ (Directory of Open Access Journals). Le modèle diamant est présent à l’échelle mondiale. Il est particulièrement répandu en Amérique latine (95 % des revues) grâce à l’émergence de grandes plateformes à financement public telles que SciELO et Redalyc, et dans une moindre mesure en Europe de l’Est et en Asie du Sud-est (par exemple en Indonésie). Les revues diamant sont souvent ancrées dans des communautés locales de chercheurs, de professionnels non universitaires et de particuliers : elles jouent un rôle important pour faire circuler la connaissance et préserver la diversité linguistique dans la science. Les revues diamant forment un modèle économique efficace. Le coût médian par article est estimé à 200 USD, contre 1 200 USD dans les revues commerciales. Leurs ressources sont généralement multiples et sans but lucratif : financement récurrent, subventions, soutien technique, bénévolat. Les revues diamant ont une productivité moindre que les revues commerciales. Leur diffusion d’articles universitaires est généralement plus restreinte, avec moins de la moitié des publications indexées par le DOAJ. Bien que le concept de « revue diamant » n’ait été introduit qu’en 2011, les publications scientifiques communautaires existent depuis longtemps. On observe depuis des décennies plusieurs types de structures communes, des éditeurs universitaires subventionnés jusqu’aux coopératives administrées par des bénévoles, et le développement de la science ouverte à la fin des années 1990 a ravivé le phénomène. Le soutien des communautés est l’un des atouts majeurs des revues diamant. En dépit de leur rôle crucial et quantifiable dans l’édition scientifique ouverte, les revues diamant sont longtemps restées oubliées des bailleurs de fonds et des politiques universitaires. Les principaux index tels que Web of Science ou Scopus ont tendance à favoriser les publications commerciales. L’archivage semble constituer un obstacle de taille, et certaines publications risquent d’être délaissées par les grandes initiatives de préservation. En 2022, de nouvelles politiques nationales et internationales, comme la recommandation de l’UNESCO sur la science ouverte et le Plan d’action pour l’accès ouvert diamant promu par la cOAlition S, sont venues soutenir le développement des revues diamant. De plus en plus, les revues diamant participent d’un nouvel écosystème de « communs scientifiques », au même titre que les infrastructures de science ouverte, les logiciels universitaires gratuits, les programmes de données ouvertes et les métriques ouvertes.