Nonlinear Equations
Mostrando 1-12 de 436 artigos, teses e dissertações.
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1. A Finite-Difference Time-Domain Formulation for Modeling Air Ionization Breakdown Streamers
Abstract A numerical model based on the finite-difference time-domain (FDTD) method is developed for calculating discharge currents and fields produced due air ionization between two electrodes. Electric conductivity σ of the ionized channel between two electrodes is calculated using non-linear equations, i.e., σ is obtained using functions of time. The fu
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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2. A Mathematical Model for Accessing Dengue Hemorrhagic Fever in Infants
ABSTRACT A mathematical model was developed to describe the dynamics of the primary infection of dengue virus in infants who were born to a mother immune to some serotype of the dengue virus. The model is given by a system of nonlinear ordinary differential equations with time-dependent variables for the number of dengue virus antibodies of the infant transf
Trends in Computational and Applied Mathematics. Publicado em: 2022
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3. FITTING AND CALIBRATING A MIXED-EFFECTS SEGMENTED TAPER MODEL FOR BRUTIAN PINE
ABSTRACT Taper models are one of several necessary tools in modern forest inventory, giving information on diameter at any point along the tree stem and this information can also be used to estimate stem volume. In this study, we used nonlinear mixed-effects (NLME) modeling approach to minimize existing statistical problems in constructing taper equations. A
CERNE. Publicado em: 2020-12
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4. Leaf area estimation with nondestructive method in cassava
ABSTRACT The objective of this study was to create a single mathematical equation able to estimate the leaf area of different cassava cultivars from one lineal dimension without destroying any plant tissue. Two hundred leaves per cultivar from ten cultivars were used to calibrate the model and more than one hundred leaves per cultivar were used to test its p
Bragantia. Publicado em: 2020-12
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5. HEIGHT-DIAMETER RELATIONSHIPS FOR Eucalyptus grandis HILL EX. MAIDEN IN MOZAMBIQUE: USING MIXED-EFFECTS MODELING APPROACH
ABSTRACT Equations express that height-diameter relationships are used to estimate tree heights that were not measured in the plots, as well as to calculate their volumes. In this study, we modelled height for Eucalyptus grandis Hill ex. Maiden stands using nonlinear mixed effect models in Mocuba District, Central Mozambique. Models were tested from 1414 tre
CERNE. Publicado em: 2020-06
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6. Conditions for the Existence of Global Solutions to Doubly Nonlinear Advection-diffusion Equations
RESUMO Neste trabalho, consideramos um problema de valor inicial para uma equação de advecção-difusão duplamente não linear, e apresentamos um valor crítico de κ até o qual o problema de valor inicial tem solução global independente do dado inicial u 0, e a partir do qual as soluções globais ainda podem existir, mas para dados iniciais u 0 satis
TEMA (São Carlos). Publicado em: 2020-04
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7. MULTILEVEL NONLINEAR MIXED-EFFECTS MODEL AND MACHINE LEARNING FOR PREDICTING THE VOLUME OF Eucalyptus SPP. TREES
ABSTRACT Volumetric equations is one of the main tools for quantifying forest stand production, and is the basis for sustainable management of forest plantations. This study aimed to assess the quality of the volumetric estimation of Eucalyptus spp. trees using a mixed-effects model, artificial neural network (ANN) and support-vector machine (SVM). The datab
CERNE. Publicado em: 2020-03
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8. ANALYTICAL EXPRESSIONS FOR THE CONCENTRATION AND CURRENT IN THE REDUCTION OF HYDROGEN PEROXIDE AT A METAL-DISPERSED CONDUCTING POLYMER FILM
A mathematical model describing the reduction of Hydrogen peroxide (H2O2) to water in a metal dispersed conducting polymer film is discussed. The model is based on a system of reaction-diffusion equations containing a non-linear term related to Michaelis-Menten kinetics of the enzymatic reaction. The approximate analytical expressions corresponding to the co
Quím. Nova. Publicado em: 2020-01
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9. Large Displacement Static Analysis of Composite Elliptic Panels of Revolution having Variable Thickness and Resting on Winkler-Pasternak Elastic Foundation
Abstract Nonlinear static response of laminated composite Elliptic Panels of Revolution Structure(s) (EPRS) having variable thickness resting on Winkler-Pasternak (W-P) Elastic Foundation is investigated in this article. Generalized Differential Quadrature (GDQ) method is utilized to obtain the numerical solution of EPRS. The first-order shear deformation th
Lat. Am. j. solids struct.. Publicado em: 20/12/2019
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10. Scaling Symmetries and Conservation Laws for Variable-coefficients Nonlinear Dispersive Equations
RESUMO. Simetrias de escala surgem em diferentes ramos da física e abordagens baseadas em simetria são poderosas ferramentas para estudar modelos invariantes por escala, pois podem fornecer leis de conservação que não são óbvias por inspeção. Nessa perspectiva, a classe de equações dispersivas não-lineares com coeficientes variáveis vc K ( m ,
TEMA (São Carlos). Publicado em: 13/12/2019
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11. A METHODOLOGY TO OBTAIN ANALYTICAL MODELS THAT REDUCE THE COMPUTATIONAL COMPLEXITY FACED IN REAL TIME IMPLEMENTATION OF NMPC CONTROLLERS
Abstract Model Predictive Control, MPC and NMPC, and real-time optimization, RTO and D-RTO, are known to help plant operability through the mitigation of impacts caused by external disturbances. However, the usage of these tools in industry requires overcoming some challenges, for instance: accurate models of the process, particularly in regard to nonlineari
Braz. J. Chem. Eng.. Publicado em: 09/12/2019
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12. New nonlinear solution of nearly incompressible hyperelastic FGM cylindrical shells with arbitrary variable thickness and non-uniform pressure based on perturbation theory
Abstract In this paper, nonlinear analysis of thick cylindrical shells with arbitrary variable thickness made of hyperelastic FGM with radially variation of material properties in nearly incompressible state under non-uniform pressure loading is presented. Thickness and pressure of the shell vary in axial direction by linear and/or nonlinear functions. The g
Lat. Am. j. solids struct.. Publicado em: 28/10/2019