Literatura académica sobre el tema "Multi-scale structuration"

The visualisation and the level of abstraction of complicated organic relations within an urban setting still remains a major problem with regard to urban discipline. This paper captures the dialectic relation within the urban network, in which the interaction between the spatial process of becoming and the temporal state of being is fundamental. ‘Envelopment’ is developed from and based upon Giddens’ structuration theory. It enables visualisation of ‘relations’ and, as problem-setting matrices, allows the fundamentals of the urban network to be itemised within forms of relationships: modalities. Deleuze and Guattari’s philosophy of deterriorialisation is also adopted into urban studies to support further investigations in respect of decoding and Translating ‘modalities’ as fundamentals in achieving continuous reproduction of Envelopment-as a topological space. Generally, topological space is defined in terms of processes and relations, Vocabularies are accepted as essences of urban dialog embodied in the system, needs to be visualised and meanings to be assigned according to their role and position in the system. In envelopment, system will be considered as macro-scale, multi-scalar topology, where all other modes of relations (amongst people, space and time) can be elaborated. The language game of Wittgenstein, as a metaphoric tool allows us to explore and group the modes of relations as vocabularies; “set of modalities”, enabling dialog upon their role and position in the system. Although the approach of Envelopment can be used as a tool, in enabling the representation of the equilibrium of state and process characteristics of system; it also helps as a tool in enabling the representation of macroscopic space-time scale; enabling representation of urban development and enabling representation of change in urban narrative. The various implementation of the Envelopment will be represented as a final discussion of the paper.

Abstract Understanding how genomes fold and organize is one of the main challenges in modern biology. Recent high-throughput techniques like Hi-C, in combination with cutting-edge polymer physics models, have provided access to precise information on 3D chromosome folding to decipher the mechanisms driving such multi-scale organization. In particular, structural maintenance of chromosome (SMC) proteins play an important role in the local structuration of chromatin, putatively via a loop extrusion process. Here, we review the different polymer physics models that investigate the role of SMCs in the formation of topologically associated domains (TADs) during interphase via the formation of dynamic loops. We describe the main physical ingredients, compare them and discuss their relevance against experimental observations.

Territorial exclusion is a multi-scalar phenomenon. However, research has tended to focus on exclusion at separate scales. This paper develops a conversation between research on the territorial exclusion of international migrants at the national scale and the territorial exclusion of lower- and working-class residents at the urban scale. Both strands of research have encountered a common empirical puzzle: territorially exclusive practices rarely comport with official government policies. The paper argues that these apparent “policy gaps”—and efforts to overcome them—can be more fruitfully studied as outcomes of the scalar structuration of legitimate violence, which shapes the way that policy-makers seek to achieve exclusionary goals. The paper suggests that this approach may be used as the platform for richer inter-disciplinary conversations between Human Geography and International Relations (IR) about territorial exclusion and the historical scaling and rescaling of legitimate violence over time.

Purpose Billions of entrepreneurs at the Base of the Pyramid (BoP) operate as small-scale producers within multi-tiered supply chain networks. Unfortunately, a majority of these entrepreneurs are simply unable to derive sufficient value from the network and are vulnerable to disasters and poverty. The purpose of this paper is to develop a typology that examines dynamic and triadic power relationships in order to create value chains for BoP producers. Design/methodology/approach This paper builds upon the available literature and a relevant historical case study to develop a typology. The validity of the typology is ascertained by examining and comparing two current BoP silk weaver communities in India. Findings The typology captures essential environmental variables and relates them to mediated and non-mediated forms of power which, in turn, shape the value derived from the supply chain network. Practical implications The typology provides specific recommendations for BoP producers, such as the formation of cooperatives, engaging in political unionization and ensuring that their social networks expand beyond local communities. Originality/value The typology brings together structuration theory and power and provides a framework for understanding supply value. This typology is generalizable to dynamic multi-tiered supply chain networks.

Realizing or appropriating value from individual firm-level IT investments has been a recurring theme in the IS literature for decades. Further, failure rates related to IT investments have been high for many years. However, realizing value from IT in settings where numerous organizations need to work together to co-develop sizable digital platforms has been undertheorized and/or hobbled with conflated theoretical constructs. To address this dearth of novel theory and accompanying empiricism, high-quality processes such as benefits management have been suggested in the scientific literature and have gained substantial interest in practice as a means for organizations to structure their routines and processes in ways that actually capture value. The complexity of this challenge suggests that there should be a renewed theoretical effort in IS to reconceptualize several extant scholarly streams. We address this challenge first by deconstructing traditional scholarly frameworks into a moderated theoretical model of multi-creation and multi-realization of IT value termed “MUIT.” The first construct in the model is based on the resource-based view; then, the model is further informed by appropriation theory, adaptive structuration theory, network governance theory, and, finally, the benefits management literature. Our variance model is a Type IV theory according to Gregor’s typology—a theory for explaining and predicting how large-scale strategic consortia can collaborate to realize greater value from IT than they could in isolation. Regarding praxis, we contribute to the understanding of how interorganizational resources and capabilities, relationships, and value realization can be spring-boarded into both successful large-scale platforms and superior realization of benefits.

Large datasets are highly valuable resources to investigate multi-scale patterns of organisms, and lay foundations for citizen science-based conservation strategies. Here, we used 1,043,262 records from 1708 to 2021 to explore the geography, taxonomy, ecology and distribution patterns of 11,556 fungal taxa in metropolitan France. Our analysis reveals a four-phase pattern of temporal recording, with a main contribution of post-1977 observations in relation with the structuration of associative mycology. The dataset shows an uneven geography of fungal recording. Four clusters of high-intensity sampling scattered across France contrast with poorly documented areas, including the Mediterranean. Basidiomycota and Agaricales highly dominate the dataset, accounting for 88.8 and 50.4% of records, respectively. The dataset is composed of many rare taxa, with 61.2% of them showing fewer than 100 records, and 20.5% recorded only once. The analysis of metadata brings to light a preponderance of the mycorrhizal guild (44.6%), followed by litter saprotrophs (31.6%) and wood saprotrophs (18.1%). Highly documented forests (76.3% of records) contrast with poorly investigated artificial (6.43%) and open habitats (10.1%). This work provides the first comprehensive overview of fungal diversity in France and identifies the Mediterranean area and open habitats as priorities to integrate into a global strategy for fungal conservation in France.

Understanding the dynamics of biodiversity has become an important line of research in theoretical ecology and, in particular, conservation biology. However, studying the evolution of ecological communities under traditional modeling approaches based on differential calculus requires species' characteristics to be predefined, which limits the generality of the results. An alternative but less standardized methodology relies on intensive computer simulation of evolving communities made of simple, explicitly described individuals. We study here the formation, evolution, and diversity dynamics of a community of virtual plants with a novel individual-centered model involving three different scales: the genetic, the developmental, and the physiological scales. It constitutes an original attempt at combining development, evolution, and population dynamics (based on multi-agent interactions) into one comprehensive, yet simple model. In this world, we observe that our simulated plants evolve increasingly elaborate canopies, which are capable of intercepting ever greater amounts of light. Generated morphologies vary from the simplest one-branch structure of promoter plants to a complex arborization of several hundred thousand branches in highly evolved variants. On the population scale, the heterogeneous spatial structuration of the plant community at each generation depends solely on the evolution of its component plants. Using this virtual data, the morphologies and the dynamics of diversity production were analyzed by various statistical methods, based on genotypic and phenotypic distance metrics. The results demonstrate that diversity can spontaneously emerge in a community of mutually interacting individuals under the influence of specific environmental conditions.

Electron multipacting and electron cloud have been identified as being the major limiting factors for the beam quality or for the cryogenic system of high-intensity positive particles accelerators. Among conditioning operational techniques and other surface structuration techniques used to decrease the Secondary Electron Yield (SEY) of surfaces, laser surface treatment is a promising method to treat in situ and at atmospheric pressure copper surface of the vacuum chamber. Here, pulsed laser irradiation of copper in parallel lines pattern led to the local ablation and deposition of aggregates of copper particulates on the surface. Tests undertaken at CERN have shown that the modification of the surface morphology by creating roughness at different scales induces a decrease of the SEY by geometrical effects. Nevertheless, the mechanical strength and dust generation of the treated surface have not been addressed yet.In this work, a qualitative analysis of the multi-scale description of the surface morphology was carried out. Scanning Electron Microscopy (SEM), Focused Ion Beam (FIB), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectroscopy (EDS) were used to investigate morphological characterization such as size and shape of the particulates, chemical composition, metallographic structures and phase transformation on the laser-processed surface.SEM and FIB examinations showed that the surface morphology depends on the local laser energy irradiating the surface and especially, relatively to the ablation threshold. TEM analysis revealed chemical composition and crystalline configuration of the treated material and helped to identify the laser modified and oxidized areas. A variety of superficial structures were observed. Potential vulnerable structures have been identified as oxidized matter redeposited on the ablated near surface. Material continuity and composition play a major role in the mechanical integrity of the generated surface morphology. The adherence of the created structures was assessed analyzing the origin of the dust extracted after mechanical stress.

Cette thèse a pour enjeu le développement de biomatériaux modulables pour l’ingénierie tissulaire. Trois types de biocomposites sont présentés, sous forme de filaments ou de membranes autoportées présentant des fibres alignées ou non. Le collagène, principal constituant des tissus conjonctifs, en est la matrice hôte. Ce biopolymère fournit l’environnement structurel et biochimique adéquat pour les cellules. Nous avons également ajouté des nanoparticules de silice (SiNPs) bio-fonctionnalisées qui jouent le rôle de plateformes multifonctionnelles, afin de moduler la topologie interne des biocomposites et/ou la présentation de ligands bioactifs. Par cette approche bionanocomposite, nous avons cherché à améliorer la réponse cellulaire en présentant de manière optimale aux cellules ces signaux structurels et/ou fonctionnels. En recherchant l’organisation moléculaire idéale qui mènerait à une synergie entre structure et fonction, nous avons montré que l’ingénierie de surface des SiNPs était un paramètre clé pour moduler les propriétés de ces biomatériaux. Nous avons pour cela développé une approche multi-échelle, de l’ingénierie de surface des SiNPs jusqu’à la modulation des interactions cellule-biomatériau, en passant par l’auto-assemblage hiérarchique du collagène en une matrice extracellulaire biomimétique. Dans le contexte de SiNPs présentant des domaines fonctionnels, nous avons aussi développé une technique de caractérisation de la structuration nanométrique de la surface en utilisant des colloïdes d’or
This work has been devoted to the design and synthesis of tunable biomaterials for tissue engineering. We have developed three types of collagen-based biocomposites, as filaments or self-supported membranes with fibers aligned or not. The host matrix is constituted by collagen, the main biopolymer in connective tissues, which naturally provides suitable structural environment to the cells together with intrinsic biochemical signals. Moreover, bio-functionalized silica nanoparticles (SiNPs) were added as multifunctional platforms to further modulate the inner topology of the composite scaffold and/or exhibit bioactive ligands. This bionanocomposite approach aimed at presenting at best structural and/or functional cues for enhanced cell bioactivity. The final goal of our studies was to find the ideal molecular organization in order to create a synergy between structure and function. To do so, we have developed a multi-scale approach, from SiNP surface engineering to the modulation of cell-biomaterial interactions, by way of collagen hierarchical self-assembly to a biomimetic extracellular matrix. SiNP surface engineering proved to be at the basis of biomaterials modularity. In the context of SiNPs presenting functional domains, we also focused on the nanoscale structuration of SiNP surface. To this aim, we developed a gold-tag spatial characterization technique with carboxylate-modified gold colloids in order to reach a high degree of spatial resolution

De nombreuses applications industrielles mettent en évidence l'importance des propriétés de mouillage des surfaces métalliques que ce soit directement pour les propriétés d'écoulement de fluides sur ces surfaces ou indirectement pour leur lien avec les phénomènes d'adhésion. Les travaux de Wenzel (1936) et de Cassie -Baxter (1944) ont montré que cette mouillabilité dépendait à la fois de la tension superficielle du solide mais aussi de sa topographie de surface. Ainsi la maîtrise et l'optimisation de ces propriétés nécessitent le contrôle de ces deux aspects, à l'image de la feuille de lotus dont le caractère super-hydrophobe réside à la fois en la présence d'une cire hydrophobe et d'une rugosité multi-échelle. Ces observations sont à l'origine, cette dernière décennie, du développement des techniques de gravures chimiques pour réaliser des texturations superficielles de matériaux et contrôler leur mouillabilité. Afin de surmonter certaines limitations de ces techniques et privilégier un procédé par voie sèche, nous avons envisagé de structurer la surface d'alliages métalliques de titane, d'aluminium, et de différents aciers inoxydables, au moyen d'un traitement de surface par laser femtoseconde. L'analyse topographique de la surface des matériaux (profilométrie optique, AFM, MEB) en fonction des paramètres d'irradiation du laser comme la densité de puissance laser, le nombre d'impulsions et le décalage latéral du faisceau en configuration balayage, a montré l'efficacité de ce procédé pour générer des texturations multi-échelles. Les différentes morphologies de textures peuvent être associées à des transitions de régimes dans l'interaction laser - matière (ripples, spikes, ...). L'analyse chimique et structurale (DRX, XPS) des surfaces traitées a mis en évidence des modifications microstructurales dues aux effets thermiques du laser ainsi qu'une évolution de l'état chimique de la surface dont les effets sur la mouillabilité sont importants. L'hydrophobie des surfaces métalliques a été considérablement accentuée par le traitement laser. Ces résultats pourront être exploités pour différentes applications industrielles notamment comme moyen de contrôler l'état de surface des moules de plasturgie.

Ce présent travail de thèse porte sur l’étude du potentiel d’un traitement de surface par laser femtoseconde comme étape de substitution aux traitements réalisés actuellement lors de la métallisation de polymère. Pour cela, l’étude des modifications chimiques et morphologiques induites par traitement laser femtoseconde ainsi que leurs influences respectives sur les propriétés d’adhérences et de mouillabilités de la surface polypropylène sont présentées. Une revue bibliographique met en évidence la faisabilité d’une modification contrôlée de la surface du polypropylène après traitement laser femtoseconde. De plus, ces modifications engendrent une évolution démontrée des propriétés de mouillage qui peuvent répondre à certaines demandes industrielles. Après traitement laser femtoseconde, la surface traitée répond de différentes manières à la sollicitation en fonction de ses propriétés intrinsèques. Les expériences d’impacts localisés et de surfaces nous ont conduits à observer trois stades de modifications topographiques pour les conditions étudiées : un phénomène d’incubation, d’accumulation et d’ablation. Ce dernier a fait l’objet d’une étude plus approfondie. De manière générale, on observe deux régimes d’ablation linéaires pour l’ensemble des densités de puissance étudiées lorsque l’on étudie la profondeur d’ablation en fonction du nombre d’impulsion et le volume d’ablation en fonction de la densité de puissance cumulée. Enfin, nous montrons que les liaisons présentes en surface après traitement sont dépendantes de deux facteurs ; la densité de puissance cumulée utilisée et l’environnement de travail. Sachant que les modifications topographiques obtenues sont de types multi-échelles, les résultats ont été analysés sur la base des modèles de Wenzel (1936) et de Cassie-Baxter (1944) relatifs à la théorie du mouillage de surfaces rugueuses. Les résultats expérimentaux et leurs corrélations avec les paramètres de rugosités 3D calculés à différentes échelles ont été traités par une analyse statistique. On observe alors un comportement mixte avec un contact intime de la goutte sur les sommets des aspérités (modèle de Wenzel) et un contact hétérogène (airpolypropylène) à une échelle mésoscopique (état « fakir » décrit par le modèle de Cassie-Baxter). Toutefois, la situation où la goute repose sur le sommet des structures (CB) n’est pas toujours stable. Nous avons étudié la transition de l’état CB à l’état W par des expériences d’évaporation. On observe que cette transition est fortement dépendante de la chimie de surface dont la contribution est prépondérante sur les propriétés d’adhérence métal/PP. En contrôlant cette propriété, il est alors possible de répondre à une problématique industrielle de galvanoplastie (adhérence augmenté par le traitement laser) ou d’électroformage (adhérence faible permettant une réplication de bonne qualité des motifs)
This work presents the potential of a femtosecond laser surface treatment as an alternative step of pretreatments during the metallization of polymer. To do this, the study of chemical and morphological modification induced by femtosecond laser treatment and their respective influences on the properties of adhesion and wettability of polypropylene surface are presented. A literature review highlights the feasibility of a controlled surface modification after femtosecond laser treatment of polypropylene (PP). In addition, it is known that these modifications changes the wetting properties and can be used to meet industrial applications development. After femtosecond laser treatment, the treated surface responds to the solicitation with different morphological comportment according to its intrinsic properties. Experiences of localized impacts and surfaces us to observe three stages of topographic changes to the conditions studied: an incubation phenomenon of accumulation and ablation. The ablation phenomenon is further study. Generally, two linear ablation regime is observed for all power densities examined when considering the depth of ablation as a function of the pulse number and the ablation volume according to the accumulated power density. Finally, we show that the bonds present on the surface after treatment are dependent on two factors: the accumulated power density used and the working environment. Knowing that topographic obtained is multi-scales, the results were analyzed on the basis of models Wenzel (W)(1936) and Cassie–Baxter (CB) (1944) which explain the theory of wetting of rough surfaces. The experimental results and their correlations with 3D roughness parameters calculated at different scales were treated by statistical analysis. We observe a mixed model behavior with intimate contact of the drop on the tops of the asperities (Wenzel model) and a heterogeneous contact (air - PP) in a mesoscopic scale (state " fakir " described by the Cassie -Baxter model). However, this situation where the drop sits on the top of asperities (CB) is not always the most stable. We have studied the transition between the CB state and the W state by evaporation experiments. It is observed that this transition is strongly dependent on the surface chemistry whose contribution is much greater than the adhesion properties metal / PP. If controlling this property, it is possible to obtain two industrial applications: electroplating (increased adhesion by laser treatment) or electroforming (low adherence to replicate the topography)

Afin de répondre aux besoins du marché de l’acier, le procédé de cokéfaction du charbon doit s’adapter. Cependant, changer les paramètres de cokéfaction du charbon, tels que la température du four, le temps de cuisson ou la composition de la pâte à coke enfournée, peut générer un endommagement prématuré de la maçonnerie des fours. En effet, la transformation du charbon en coke s’accompagne d’une poussée sur les parois du four fortement dépendantes d’un grand nombre de paramètres. Afin d’anticiper ce problème, un projet européen nommé « Swelling PRessure In a coke oven, Transmission on oven walls and COnsequences on wall » a été mis en place. Cette thèse s’inscrit dans ce programme et vise à déterminer la poussée maximale pouvant être admise par un piédroit de cokerie lors de la pyrolyse du charbon. Pour modéliser ces structures composées de plusieurs centaines de milliers de briques, le point de vue macroscopique est le plus approprié. La maçonnerie est remplacée par un matériau homogène équivalent dont le comportement varie en fonction de l’état d’endommagement de la maçonnerie, ramené localement à un état d’ouverture des joints de mortier. Afin de détecter ces ouvertures, un critère de type Mohr-Coulomb en contraintes est utilisé. Il repose sur la comparaison des limites à rupture d’un sandwich brique-Mortier déterminé expérimentalement à haute température avec les contraintes mésoscopiques issues de la simulation. Un protocole expérimental novateur a été développé pour caractériser la tenue en traction du sandwich brique / mortier / brique jusqu’à 1000°C. Les limites à rupture issues de cet essai de traction directe ont été comparées à celles obtenues par des essais de fendage réalisés à l’université de Leoben. Les résultats sont concordants et confirment l’importance de l’état de surface avant maçonnage. Selon l’état d’endommagement considéré, les contraintes mésoscopiques sont obtenues grâce à un tenseur de localisation ou grâce à une sous-Structuration. Cette étape de sous-Structuration consiste à simuler localement une cellule à l’échelle mésoscopique en lui appliquant le champ de déplacement macroscopique obtenu grâce à la simulation. L’outil numérique a été validé par confrontation avec un cas test de référence. Pour finir, l’outil numérique développé a été utilisé pour caractériser l’influence de différents paramètres tels que la prise en compte de la thermique, la mise en compression de la structure…. Enfin, la simulation de cuissons sur des piédroits complets (sains ou initialement endommagés) a été réalisée. L’importance de l’endommagement initial est clairement soulignée par les résultats. Enfin, un nouveau modèle, appelé « deux carneaux avec poutres», est proposé pour réduire le coût de calcul. Plus complet que le modèle « deux carneaux » utilisé au CPM, il donne accès à de très bons résultats pour un coût nettement moindre que celui du piédroit complet avec homogénéisation et sous-Structuration
To face coke and steel market requirements, the coking process has to be more flexible. Changing process parameters such as coking temperature, blend composition and cooking time can damaged coke oven battery heating wall. Indeed, the coking process generates a swelling pressure on wall which depends on a lot of parameters. To study this point, a European project named « Swelling PRessure In a coke oven, Transmission on oven walls and COnsequences on wall » has been set up. This work is a part of it and aims to determine the admissible pushing pressure for the coke oven heating walls to prevent crack formation. To model large masonries composed of numerous bricks, a mesoscopic point of view is more appropriate. Bricks and mortar are replaced by a Homogeneous Equivalent Material (HEM) whose behaviour depends on the joint state. In order to represent joint opening mechanism, a Mohr-Coulomb criterion in stress is used. This criterion compares the level of stress to the ultimate tensile or shear stress at mesoscopic scale. Ultimate stresses are obtained thanks to an experimental campaign using a new protocol developed at PRISME Laboratory. The brick-Mortar behaviour is experimentally characterised at high temperature (20°C to 1000°C). To validate the tensile test developed, a second experimental campaign using “wedge splitting tests” has been done at Leoben University. Results are similar and confirm the importance of the brick surface state. Depending on the initial damage of the structures, mesoscopic stresses are obtained by localization tensor or by sub-Modelling. The sub-Modelling step aims to simulate a local part of the masonry at the mesoscopic scale. This step aims to simulate with a mesoscopic point of view a local part of the global model. This numerical tool has been validated thanks to a literature test. Finally, the numerical tool has been used to characterise the influence of some parameters (thermal, force due to the cross tie rod,..). Next, the simulation of the whole coke oven heating wall has been performed (undamaged or initially damaged masonry). These FE simulations show the influence of initial damage on the final masonry damage. Finally, a two flues model with beams is proposed to take into account compression due to cross tie rod and to limit computational cost. It permits to obtain better results than the existing two flues model used at CPM with a lower cost compared to the whole coke oven heating wall model