Examinando por Materia "model"
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Ítem BDNG: A dublin core-based architecture for digital libraries(2005-01-01) Montoya, E.; Ruiz, M.; Giraldo, J.; Universidad EAFIT. Departamento de Ingeniería de Sistemas; I+D+I en Tecnologías de la Información y las ComunicacionesDigital Libraries will be one of the main ways to access structured information through the Internet. Information related to resources or objects is known as metadata. Several metadata models have been proposed; however, the model proposed by the Dublin Core Metadata Initiative (DCMI) [1] has demonstrated great utility in digital libraries. The simplicity and generality of DCMI has facilitated the deployment of digital libraries and their interoperability. This paper proposes DCMI as metadata model in our own Digital Library Architecture (Biblioteca Digital de Nueva Generación -BDNG). We have extended DCMI and used some elements of DC-Library application profile (DC-Lib) [2] in addition to new elements not previously considered. This paper presents the metadata models for the following applications: digital library of EAFIT University (BDEeafit), integration of digital or referential libraries (BDMetaLib) and digital library for E-Learning systems (BDEI). This paper also describes the general architecture of BDNG.Ítem Early Miocene CO2 estimates from a Neotropical fossil leaf assemblage exceed 400 ppm(Wiley-Blackwell Publishing Ltd, 2018-11-01) Londoño L.; Royer D.L.; Jaramillo C.; Escobar J.; Foster D.A.; Cárdenas-Rozo A.L.; Wood A.; Universidad EAFIT. Departamento de Ciencias; Biodiversidad, Evolución y ConservaciónPremise of the Study: The global climate during the early Miocene was warmer than the present and preceded the even warmer middle Miocene climatic optimum. The paleo-CO2 records for this interval suggest paradoxically low concentrations (<450 ppm) that are difficult to reconcile with a warmer-than-present global climate. Methods: In this study, we use a leaf gas-exchange model to estimate CO2 concentrations using stomatal characteristics of fossil leaves from a late early Miocene Neotropical assemblage from Panama that we date to 18.01 ± 0.17 Ma via 238U/206Pb zircon geochronology. We first validated the model for Neotropical environments by estimating CO2 from canopy leaves of 21 extant species in a natural Panamanian forest and from leaves of seven Neotropical species in greenhouse experiments at 400 and 700 ppm. Key Results: The results showed that the most probable combined CO2 estimate from the natural forests and 400 ppm experiments is 475 ppm, and for the 700 ppm experiments is 665 ppm. CO2 estimates from the five fossil species exhibit bimodality, with two species most consistent with a low mode (528 ppm) and three with a high mode (912 ppm). Conclusions: Despite uncertainties, it is very likely (at >95% confidence) that CO2 during the late early Miocene exceeded 400 ppm. These results revise upwards the likely CO2 concentration at this time, more in keeping with a CO2-forced greenhouse climate. © 2018 Botanical Society of AmericaÍtem Impacto de la relación de las habilidades gerenciales y las variables financieras en la rentabilidad operativa : análisis para una muestra de mipymes colombianas(2019) Salazar Duque, Juan Victor; Morales Isaza, Sergio Andrés; Saavedra Caballero, FabiolaThis research aims to create, from a multiple linear regression model, an empirical contribution to determine how the characteristics and skills of managers, in addition to the financial variables traditionally used, relate to and impact the profitability and sustainability of micro, small and medium-sized companies in the Colombian context. To achieve this objective, we used the financial and managerial information of 2016 of 35 Colombian MiPymes companies from different economic sectors; 25 financial ratios were calculated through the financial statements, 10 management skills were measured through surveys and 10 characterization variables were defined related to each company and its manager to be used as independent variables in a multiple linear regression model using the EBITDA margin as a dependent variable in order to represent the profitability and sustainability of these companies. It was found that some characteristic variables of the managers and senior managers of the companies, such as their self-confidence, their affinity to face new challenges, their role, among others, significantly affect the behavior of the EBITDA Margin, demonstrating that there is a relationship between the way these managers make decisions and the performance of the company.Ítem Observations about an approximate algorithm for the point robot motion planning problem(IEEE Computer Society, 2002-01-01) Trefftz, C.; Trefftz, H.; Universidad EAFIT. Departamento de Ingeniería de Sistemas; I+D+I en Tecnologías de la Información y las ComunicacionesObservations about an approximate parallel algorithm for the point robot motion planning problem are presented. The algorithm solves not only the original problem, but related problems as well. © 2002 IEEE.Ítem Remote sensing-based measurement of Living Environment Deprivation: Improving classical approaches with machine learning(Public Library of Science, 2017-05-02) Arribas-Bel D; Patino JE; Duque JC; Universidad EAFIT. Departamento de Economía y Finanzas; Research in Spatial Economics (RISE)This paper provides evidence on the usefulness of very high spatial resolution (VHR) imagery in gathering socioeconomic information in urban settlements. We use land cover, spectral, structure and texture features extracted from a Google Earth image of Liverpool (UK) to evaluate their potential to predict Living Environment Deprivation at a small statistical area level. We also contribute to the methodological literature on the estimation of socioeconomic indices with remote-sensing data by introducing elements from modern machine learning. In addition to classical approaches such as Ordinary Least Squares (OLS) regression and a spatial lag model, we explore the potential of the Gradient Boost Regressor and Random Forests to improve predictive performance and accuracy. In addition to novel predicting methods, we also introduce tools for model interpretation and evaluation such as feature importance and partial dependence plots, or cross-validation. Our results show that Random Forest proved to be the best model with an R2 of around 0.54, followed by Gradient Boost Regressor with 0.5. Both the spatial lag model and the OLS fall behind with significantly lower performances of 0.43 and 0.3, respectively. © 2017 Arribas-Bel et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Ítem Simulating soft tissues using a GPU approach of the mass-spring model(2010-01-01) Leon, C.A.D.; Eliuk, S.; Gomez, H.T.; Universidad EAFIT. Departamento de Ingeniería de Sistemas; I+D+I en Tecnologías de la Información y las ComunicacionesThe recent advances in the fields such as modeling bio-mechanics of living tissues, haptic technologies, computational capacity, and graphics realism have created conditions necessary in order to develop effective surgical training using virtual environments. However, virtual simulators need to meet two requirements, they need to be real-time and highly realistic. The most expensive computational task in a surgical simulator is that of the physical model. The physical model is the component responsible to simulate the deformation of the anatomical structures and the most important factor in order to obtain realism. In this paper we present a novel approach to virtual surgery. The novelty comes in two forms: specifically a highly realistic mass-spring model, and a GPU based technique, and analysis, that provides a nearly 80x speedup over serial execution and 20x speedup over CPU based parallel execution. ©2010 IEEE.