1,720,986 research outputs found
Design and HPC implementation of unsupervised Kernel methods in the context of molecular dynamics
No full textThe thesis represents an extensive research in the multidisciplinary domain formed by the cross contamination of unsupervised learning and molecular dynamics, two research elds that are coming close creating a breeding ground for valuable new concepts and methods. In this context, at rst, we describe a novel engine to perform large scale kernel k-means clustering. We introduce a two-fold approximation strategy to minimize the kernel k-means cost function in which the trade-off between accuracy and execution time is automatically ruled by the available system memory
Heat Release Rate Markers for the Adelaide Jet in Hot Coflow Flame
No full textIn the present work, the correlation between the Heat Releaser Rate (HRR) and species mole fractions and net reaction rates is studied. The PaSR closure model is employed in a RANS framework to implement a detailed kinetic scheme, including the excited species OH*, used as a HRR marker. The effect of oxygen dilution on the combustion regime is investigated, as it can lead to Moderate or Intense Low-Oxygen Dilution (MILD) conditions. Two cases with different levels of oxygen concentration are analyzed. The results suggest the possibility of combining chemical species to construct an appropriate scalar to achieve better correlation with the HRR. It is found that typical markers such as radicals O, OH, OH* correlate fairly well with the HRR but improved correlations can be achieved with appropriate species mole fractions combinations, particularly for the MILD region of the flame.This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 714605. The author Marco Ferrarotti also wishes to thank Fonds de la Recherche Scientifique FNRS Belgium for financing his research.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Using Principal Paths to Walk Through Music and Visual Art Style Spaces Induced by Convolutional Neural Networks
Full text linkComputational intelligence, particularly deep learning, offers powerful tools for discriminating and generating samples such as images. Deep learning methods have been used in different artistic contexts for neural style transfer, artistic style recognition, and musical genre recognition. Using a constrained manifold analysis protocol, we discuss to what extent spaces induced by deep-learning convolutional neural networks can capture historical/stylistic progressions in music and visual art. We use a path-finding algorithm, called principal path, to move from one point to another. We apply it to the vector space induced by convolutional neural networks. We perform experiments with visual artworks and songs, considering a subset of classes. Within this simplified scenario, we recover a reasonable historical/stylistic progression in several cases. We use the principal path algorithm to conduct an evolutionary analysis of vector spaces induced by convolutional neural networks. We perform several experiments in the visual art and music spaces. The principal path algorithm finds reasonable connections between visual artworks and songs from different styles/genres with respect to the historical evolution when a subset of classes is considered. This approach could be used in many areas to extract evolutionary information from an arbitrary high-dimensional space and deliver interesting cognitive insights
Evaluation of Modeling Approaches for MILD Combustion Systems With Internal Recirculation
No full textNumerical simulations employing two different modeling approaches are performedand validated against experimental results from a moderate or intense low-oxygendilution (MILD) system with internal recirculation. The flamelet-generated manifold (FGM)and partially stirred reactor (PaSR) closures are employed in a Reynolds-averagedNavier–Stokes (RANS) framework to carry out the numerical simulations. The resultsshow that the FGM model strongly overpredicts temperature profiles in the reactiveregion, while yielding better results along the central thermocouple. The PaSR closuresbased on a prescribed mixing time constant, Cmix, of 0.01, 0.1, and 0.5 are compared,showing that a Cmix value of 0.5 is the most appropriate choice for the cases underinvestigation. A PaSR formulation allowing local estimation of the Cmix value is found toprovide improved results for both the lateral and central thermocouples. A flame indexanalysis, used to assess the ability of FGM and PaSR to capture intense mixing of thecyclonic burner, indicates how the FGM model predicts a typical non-premixed regionafter the injection zone, contrary to the experimental observation.info:eu-repo/semantics/publishe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Finite-rate chemistry modelling of non-conventional combustion regimes using a Partially-Stirred Reactor closure: combustion model formulation and implementation details
Full text linkThe present work focuses on the numerical simulation ofModerate or Intense Low oxygen Dilution combustion condition, using thePartially-Stirred Reactor model for turbulence-chemistry interactions.The Partially-Stirred Reactor model assumes that reactions are confinedin a specific region of the computational cell, whose mass fractiondepends both on the mixing and the chemical time scales. Therefore, theappropriate choice of mixing and chemical time scales becomes crucial toensure the accuracy of the numerical simulation prediction. Results showthat the most appropriate choice for mixing time scale in Moderate orIntense Low oxygen Dilution combustion regime is to use a dynamicevaluation, in which the ratio between the variance of mixture fractionand its dissipation rate is adopted, rather than global estimations basedon Kolmogorov or integral mixing scales. This is supported by thevalidation of the numerical results against experimental profiles oftemperature and species mass fractions, available from measurements onthe Adelaide Jet in Hot Co-flow burner. Different approaches for chemicaltime scale evaluation are also compared, using the species formationrates, the reaction rates and the eigenvalues of the formation rateJacobian matrix. Different co-flow oxygen dilution levels and Reynoldsnumbers are considered in the validation work, to evaluate theapplicability of Partially-Stirred Reactor approach over a wide range ofoperating conditions. Moreover, the influence of specifying uniform andnon-uniform boundary conditions for the chemical scalars is assessed. Thepresent work sheds light on the key mechanisms of turbulence-chemistryinteractions in advanced combustion regimes. At the same time, itprovides essential information to advance the predictive nature ofcomputational tools used by scientists and engineers, to support thedevelopment of new technologies.This work has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska- Curie grant agreement No 643134.info:eu-repo/semantics/publishe
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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