Examinando por Materia "Computational model"
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Ítem Exploring Undergraduate Students' Computational Modeling Abilities and Conceptual Understanding of Electric Circuits(Institute of Electrical and Electronics Engineers Inc., 2018-08-01) Ortega-Alvarez J.D.; Sanchez W.; Magana A.J.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de ProcesosContribution: This paper adds to existing literature on teaching basic concepts of electricity using computer-based instruction; findings suggest that students can develop an accurate understanding of electric circuits when they generate multiple and complementary representations that build toward computational models. Background: Several studies have explored the efficacy of computer-based, multi-representational teaching of electric circuits for novice learners. Existing research has found that instructional use of computational models that move from abstract to concrete representations can foster students' comprehension of electric circuit concepts, but other features of effective instruction using computational models need further investigation. Research Questions: 1) Is there a correlation between students' representational fluency and their ability to reason qualitatively on electric circuits? and 2) Is the quality of student-generated computational representations correlated to their conceptual understanding of electric circuits? Methodology: The study comprised two cases in which 51 sophomore-engineering students completed a voluntary assignment designed to assess their representational fluency and conceptual understanding of electric circuits. Qualitative insights from the first case informed the design of a scoring rubric that served as both the assessment and the data collection instrument. Findings: The results suggest that a multi-representational approach aimed at the construction of computational models can foster conceptual understanding of electric circuits. The number and quality of students' representations showed a positive correlation with their conceptual understanding. In particular, the quality of the computational representations was found to be highly, and significantly, correlated with the correctness of students' answers to qualitative reasoning questions. © 1963-2012 IEEE.Ítem Improvement of a knock model for natural gas SI engines through heat transfer evaluation(Springer-Verlag France, 2018-11-01) Sierra Parra A.F.; Díaz Torres A.G.; Sierra Parra A.F.; Díaz Torres A.G.; Universidad EAFIT. Departamento de Ingeniería de Producción; Ingeniería, Energía, Exergía y Sostenibilidad (IEXS)Knock is an abnormal combustion phenomena capable of causing serious damage to spark ignition engines, and is a constraint to reach the maximum potential of the engine, since strategies to increase power output and improve efficiency such as turbocharging, increased compression ratio and the advancement of spark timing, also increase the possibility of knock occurrence. Therefore, it is crucial to take into account the limits imposed by knock in the design and operating conditions of the engine when using an engine computational model. In this article a zero-dimensional two-zone engine model, coupled with a chemical kinetic model for knock detection through end-gas auto-ignition is developed and validated, for a natural gas engine. Given the importance of an accurate knock prediction, five heat transfer coefficient correlations are compared to find the most suitable to predict the knock occurrence, through calculation of a knock criterion. Correlations from Sitkei and Annand were the most suitable to predict this knock criterion for the experimental data used, and the Sitkei correlation was later tested in a parametric study to predict the effect of spark timing, compression ratio, equivalence ratio and inlet temperature in knock occurrence and intensity. Results were in accordance with real engine behaviour when knock occurs. © 2017, Springer-Verlag France SAS, part of Springer Nature.Ítem On efficient methods for sensitivity analysis of FEM problems using hypercomplex numbers(Universidad EAFIT, 2019) Aguirre Mesa, Andrés Mauricio; García Ruiz, Manuel JulioÍtem A survey on static and quasi-static finite element models of the human cervical spine(Springer-Verlag France, 2018-05-01) Suarez-Escobar M.; Rendon-Velez E.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Finite element analyses are an important source of information on the biomechanical behaviour of the cervical spine; as well as an important tool in the design and evaluation of spinal instrumentation. This article presents a comprehensive survey of the finite element models of the cervical spine that have been used to study its pathological/nonpathological biomechanics under static/quasi-static loading conditions. Publications that met the inclusion criteria were analysed to extract parameters relative to model identification (e.g., spine segment, population, utility, limitations), model structure (e.g., loading/boundary conditions, anatomical structures, constitutive representation), simulation structure (e.g., software), verification (e.g., convergence) and validation (e.g., validated procedure/output, assumptions). Besides summarizing different modelling approaches with their associated parameters, this article outlines generalities and issues related to the obtainment of such models. The survey shows that authors often fail to report parameters that are critical for the reproducibility of results and that, even with fully reported parameters, these models are inherently difficult to replicate because they generally are patient-specific with their geometry based on data from in-house specimens/subjects. Overall, while the survey contributes to an understanding of the implications of following different modelling approaches and allows to take advantage of previously developed models, further research is required to improve the accuracy and utility of these models. © 2017, Springer-Verlag France SAS, part of Springer Nature.