Numerical
Mostrando 13-24 de 4064 artigos, teses e dissertações.
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13. A Model of Social Distancing for Interacting Age-Distributed Multi-Populations: An Analysis of Students’ In-Person Return to Schools
ABSTRACT Because of the current scenario of the SARS-CoV-2 (COVID-19) pandemic in Brazil, whose vaccination campaign is in its initial stage, government authorities have pointed towards the complete reopening of the economy. And recently, for the in-personal return of classroom teaching in schools. Given the family relationship, one of the questions that rem
Trends in Computational and Applied Mathematics. Publicado em: 2022
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14. A New Miniaturized Low-Profile and Stable Dual-Band FSS with 2.5D Structure for ISM Bands
Abstract Based on 2.5-Dimensional (2.5D) frequency selective surface (FSS) structures, a new miniaturized frequency selective surface structure is proposed in this work to operate as a bandreject filter in the 2.4 GHz (2400 to 2483.5 MHz) and 5 GHz (5150 to 5350 MHz and 5470 to 5725 MHz) ISM (Industrial, Scientific, and Medical) bands. The FSS has the metall
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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15. Anomalous Diffusion with Caputo-Fabrizio Time Derivative: an Inverse Problem
ABSTRACT In this work we identify the source in a 1D anomalous diffusion equation, from measurements of the concentration at a finite number of points. We use Caputo-Fabrizio time fractional derivative to model the phenomenon. Separating variables, we arrive to a linear system which provides approximate values for the Fourier coefficients of the unknown sour
Trends in Computational and Applied Mathematics. Publicado em: 2022
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16. Strong Stability Preserving Runge-Kutta Methods Applied to Water Hammer Problem
ABSTRACT The characteristic method of lines is the most used numerical method applied to the water hammer problem. It transforms a system of partial differential equations involving the independent variables time and space in two ordinary differential equations along the characteristics curves and then solve it numerically. This approach, although showing gr
Trends in Computational and Applied Mathematics. Publicado em: 2022
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17. A Defected Ground Structure Based on Matryoshka Geometry
Abstract A Defected Ground Structure, DGS, based on matryoshka geometry is described in this paper. The proposed DGS geometry is outlined and initial design equations are presented. Four prototypes, with resonant frequencies 2.17 GHz, 2.44 GHz, 2.99 GHz and 3.73 GHz, were designed, fabricated and characterized, observing a good agreement between measured and
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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18. Design and Implementation of Microwave Dual-Band Pass Interdigital Filter Using an Analytical Approach
Abstract In this paper, benefiting from frequency transformation between the normalized frequency domain of low-pass prototype frequencies and the real frequency domain of the filter, a purely analytical procedure for dual-band filter design is used. The coupling matrix of the filter is analytically extracted, without the need to perform numerical optimizati
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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19. Efficient Low-Complexity Optimized Channel Estimating Methods for OFDM-Based Low-Voltage Broadband Power Line Communication Systems
Abstract Broadband Power Line Communication (BB-PLC) technology enables data transmission for smart grid applications. Nevertheless, channel equalizers are required in the receiver to estimate and compensate for the nonlinear time-variant impulse response and noise interference effects introduced by the BB-PLC channel. In this paper, we append the Particle S
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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20. Numerical simulation of wind-driven ventilation of a three-generic low-rise building in various geometrical configurations
Resumo A ventilação natural é a principal estratégia passiva para a obtenção do conforto térmico no interior das edificações, além de promover a renovação do ar ambiente, tornando-o mais saudável. Nas últimas décadas, a Dinâmica dos Fluidos Computacional mostrou-se uma ferramenta eficiente para estimar a ventilação natural. Diante disso, o
Ambiente Construído. Publicado em: 2022
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21. A Nodal-iterative Technique for Criticality Calculations in Multigroup Neutron Diffusion Models
ABSTRACT In this work, a nodal and iterative technique to evaluate the effective multiplication factor as well as the neutron flux, in multigroup diffusion problems, is presented. An iterative scheme, similar to the source iteration method, is implemented to decouple the system of differential equations which is the fundamental mathematical model. Then, anal
Trends in Computational and Applied Mathematics. Publicado em: 2022
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22. Numerical analysis of reinforced concrete beam subject to pitting corrosion
Resumo Neste artigo é apresentado um estudo numérico sobre os efeitos da corrosão induzida por cloreto na vida útil de elementos estruturais. Um modelo mecânico bidimensional geometricamente não linear baseado no Método dos Elementos Finitos (MEF) foi desenvolvido para a análise de estruturas de concreto armado. O estágio de iniciação da corrosão
Ambiente Construído. Publicado em: 2022
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23. Prevalence of primary dysmenorrhea and associated factors in adult women
SUMMARY OBJECTIVE: This study aimed to assess the prevalence and factors associated with primary dysmenorrhea in a sample of adult women. METHODS: A cross-sectional study was carried out with women aged between 19 and 49 years from a city of northeastern Brazil. Sociodemographic, gynecological, and obstetric variables were assessed by questionnaires and in
Revista da Associação Médica Brasileira. Publicado em: 2022
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24. Hypothyroxinemia in sick term neonates and its risk factors in an extramural neonatal intensive care unit: a prospective cohort study
ABSTRACT Objective: Thyroid functions in the sick newborns may be altered in the first week of life. Transient hypothyroxinemia has been reported in these babies, which could be due to the immaturity of the hypothalamic-pituitary-thyroid axis or to acute illness. We conducted this study to estimate the incidence of hypothyroxinemia and determine its risk fa
Archives of Endocrinology and Metabolism. Publicado em: 2022