2,135 research outputs found

    Multiscale Phenomenology of the Cosmic Web

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    We analyze the structure and connectivity of the distinct morphologies that define the Cosmic Web. With the help of our Multiscale Morphology Filter (MMF), we dissect the matter distribution of a cosmological Λ\LambdaCDM N-body computer simulation into cluster, filaments and walls. The MMF is ideally suited to adress both the anisotropic morphological character of filaments and sheets, as well as the multiscale nature of the hierarchically evolved cosmic matter distribution. The results of our study may be summarized as follows: i).- While all morphologies occupy a roughly well defined range in density, this alone is not sufficient to differentiate between them given their overlap. Environment defined only in terms of density fails to incorporate the intrinsic dynamics of each morphology. This plays an important role in both linear and non linear interactions between haloes. ii).- Most of the mass in the Universe is concentrated in filaments, narrowly followed by clusters. In terms of volume, clusters only represent a minute fraction, and filaments not more than 9%. Walls are relatively inconspicous in terms of mass and volume. iii).- On average, massive clusters are connected to more filaments than low mass clusters. Clusters with M1014M \sim 10^{14} M_{\odot} h1^{-1} have on average two connecting filaments, while clusters with M1015M \geq 10^{15} M_{\odot} h1^{-1} have on average five connecting filaments. iv).- Density profiles indicate that the typical width of filaments is 2\Mpch. Walls have less well defined boundaries with widths between 5-8 Mpc h1^{-1}. In their interior, filaments have a power-law density profile with slope γ1{\gamma}\approx -1, corresponding to an isothermal density profile.Comment: 28 pages, 22 figures, accepted for publication in MNRAS. For a high-res version see http://www.astro.rug.nl/~weygaert/webmorph_mmf.pd

    History of art paintings through the lens of entropy and complexity

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    Art is the ultimate expression of human creativity that is deeply influenced by the philosophy and culture of the corresponding historical epoch. The quantitative analysis of art is therefore essential for better understanding human cultural evolution. Here we present a large-scale quantitative analysis of almost 140 thousand paintings, spanning nearly a millennium of art history. Based on the local spatial patterns in the images of these paintings, we estimate the permutation entropy and the statistical complexity of each painting. These measures map the degree of visual order of artworks into a scale of order-disorder and simplicity-complexity that locally reflects qualitative categories proposed by art historians. The dynamical behavior of these measures reveals a clear temporal evolution of art, marked by transitions that agree with the main historical periods of art. Our research shows that different artistic styles have a distinct average degree of entropy and complexity, thus allowing a hierarchical organization and clustering of styles according to these metrics. We have further verified that the identified groups correspond well with the textual content used to qualitatively describe the styles, and that the employed complexity-entropy measures can be used for an effective classification of artworks.Comment: 10 two-column pages, 5 figures; accepted for publication in PNAS [supplementary information available at http://www.pnas.org/highwire/filestream/824089/field_highwire_adjunct_files/0/pnas.1800083115.sapp.pdf

    User-driven Page Layout Analysis of historical printed Books

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    International audienceIn this paper, based on the study of the specificity of historical printed books, we first explain the main error sources in classical methods used for page layout analysis. We show that each method (bottom-up and top-down) provides different types of useful information that should not be ignored, if we want to obtain both a generic method and good segmentation results. Next, we propose to use a hybrid segmentation algorithm that builds two maps: a shape map that focuses on connected components and a background map, which provides information about white areas corresponding to block separations in the page. Using this first segmentation, a classification of the extracted blocks can be achieved according to scenarios produced by the user. These scenarios are defined very simply during an interactive stage. The user is able to make processing sequences adapted to the different kinds of images he is likely to meet and according to the user needs. The proposed “user-driven approach” is capable of doing segmentation and labelling of the required user high level concepts efficiently and has achieved above 93% accurate results over different data sets tested. User feedbacks and experimental results demonstrate the effectiveness and usability of our framework mainly because the extraction rules can be defined without difficulty and parameters are not sensitive to page layout variation

    3D printing of hierarchical scaffolds based on mesoporous bioactive glasses (MBGs)-fundamentals and applications

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    The advent of mesoporous bioactive glasses (MBGs) in applied bio-sciences led to the birth of a new class of nanostructured materials combining triple functionality, that is, bone-bonding capability, drug delivery and therapeutic ion release. However, the development of hierarchical three-dimensional (3D) scaffolds based on MBGs may be difficult due to some inherent drawbacks of MBGs (e.g., high brittleness) and technological challenges related to their fabrication in a multiscale porous form. For example, MBG-based scaffolds produced by conventional porogen-assisted methods exhibit a very low mechanical strength, making them unsuitable for clinical applications. The application of additive manufacturing techniques significantly improved the processing of these materials, making it easier preserving the textural and functional properties of MBGs and allowing stronger scaffolds to be produced. This review provides an overview of the major aspects relevant to 3D printing of MBGs, including technological issues and potential applications of final products in medicine

    Develop a bladder assisted RTM tool to manufacture seat posts with glass fiber and CNT-epoxy resin

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    In this project, a bladder-assisted Resin Transfer Moulding tool to manufacture glass fiber bicycle seat posts with epoxy resin charged with carbon nanotubes (CNTs) is developed through the application of a "Systematic Approach to the design of Technical Systems and Products" guideline to provide an optimum solution for the filtering of CNTs during the injection process. The impregnation process is identified as the key characteristic on the tool development. The bladder assisted-RTM process parameters and manufacturing seat post features are evaluated to define the requirements that fulfill the main task, a homogeneous distribution of CNTs through the fiber glass reinforcement. According to the requirements, the task is divided in function and subfunctions to be fulfilled by the tool development. Interfaces between sub-functions are established in order to re-organize them into realizable modules. This module structure showed a preliminary indication for the breakdown of solution into realizable groups or elements, and together with their interfaces facilitated an efficient distribution of design effort. Tool constituent elements are designated and multiple principle solutions are provided for every element. Once selected the most adequate individual solution, a tool concept design is presented and begins the layouts development for the individual modules (Housing shape, Cooling system, Front cover with compressed air connection, Rear cover with resin injection port, Rear cover with airextraction exhaust, closing device, centering of the tool components, gaskets for the tightness and bladder as core design). Detailed drawings and calculations are performed to confirm that the design solution meets the requirements of the general task. The impregnation concept process using the inflatable bladder designed is explained, showing the collapsible channel operation in order to infuse correctly the braided glass fiber reinforcement using the high viscosity resin due the CNTs addition. At the end of the project, manufacturing tests are done to select the inflatable bladder with three different elastic materials using a reduced tool. After bladder material selection, a real scale tool is designed and constructed to manufacture a simple inflatable bladder, as first approach to the final bladder manufacturing. For the bladder manufacturing, a real scale bladder dipping mandrel is manufactured using water soluble fugitive core material.Ingeniería Técnica en Mecánic

    Computational methods for biofabrication in tissue engineering and regenerative medicine - a literature review

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    This literature review rigorously examines the growing scientific interest in computational methods for Tissue Engineering and Regenerative Medicine biofabrication, a leading-edge area in biomedical innovation, emphasizing the need for accurate, multi-stage, and multi-component biofabrication process models. The paper presents a comprehensive bibliometric and contextual analysis, followed by a literature review, to shed light on the vast potential of computational methods in this domain. It reveals that most existing methods focus on single biofabrication process stages and components, and there is a significant gap in approaches that utilize accurate models encompassing both biological and technological aspects. This analysis underscores the indispensable role of these methods in understanding and effectively manipulating complex biological systems and the necessity for developing computational methods that span multiple stages and components. The review concludes that such comprehensive computational methods are essential for developing innovative and efficient Tissue Engineering and Regenerative Medicine biofabrication solutions, driving forward advancements in this dynamic and evolving field
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