Avaliação das condições de contorno da teoria de Hertz, comparando os resultados analíticos e numéricos a partir de simulações em software de elementos finitos

The objective of this study was to present the comparison between analytical and numerical results trying to identify the differences and behaviors of the variation of the principal stresses and the maximum contact pressure for different model configurations. The analytical equations of the theory of Hertz from the boundary conditions adopted by him were differences are shown. A step-by-step of developing the model indicating the geometric dimensions, surface contact, type of contact, the formulation used by the software, type of mesh, as well as the boundary conditions and load was presented. In the results, the stresses calculated analytically and compared with the stresses obtained by the finite element simulation software indicating the changes have been made

Análise teórica e experimental de uma ventaneira de alto forno, visando seu comportamento térmico e fluidodinâmico

In this work, it was studied the thermal and fluid dynamic behavior from theorical and experimental point of view of a blast furnace tuyere. The tuyere is responsible for the hot air insuflation into the blast furnace. The parameter used in the comparison was the difference between the cooling water inlet and outlet temperatures. There were used forced convection correlations inside circular sections with adequations for non circular sections. Based on operations dates of flux and thermal loads it was possible to model numerically the tuyere, and, since it was obtained the wall temperatures, estimate the conduction and convection resistances and the heat flux through the walls in contact with the water. The total heat fluxes from wall to water were applied to the energy conservation equation where could be estimated the theorical temperature variation. Compared to the real value, the theorical value presented a difference of 0,2 °C. Considering that the boundary conditions around the tuyere are transitories and that your channels have some rugosity irregularities we can consider the estimation method for cooling system coherent with the real operational parameters

Potenciais singulares na equação de Schrodinger unidimensional via transformada de Laplace

The present work has as its goal to treat well known and interesting unidimensional cases from quantum mechanics through an unusual approach within this eld of physics. The operational method of Laplace transform, in spite of its use by Erwin Schrödinger in 1926 when treating the radial equation for the hydrogen atom, turned out to be forgotten for decades. However, the method has gained attention again for its use as a powerful tool from mathematical physics applied to the quantum mechanics, appearing in recent works. The method is specially suitable to the approach of cases where we have potential functions with even parity, because this implies in eigenfunctions with de ned parity, and since the domain of this transform ranges from 0 to ∞, it su ces that we nd the eigenfunction in the positive semi axis and, with the boundary conditions imposed over the eigenfunction at the origin plus the continuity (discontinuity) of the eigenfunction and its derivative, we make the odd, even or both parity extensions so we can get the eigenfunction along all the axis. Factoring the eigenfunction behavior at in nity and origin, we take the due care with the points that might bring us problems in the later steps of the solving process, thus we can manipulate the Schrödinger's Equation regardless of time, so that way we make it convenient to the application of Laplace transform. The Chapter 3 shows the methodology that must be followed in order to search for the solutions to each problem

Condições de otimidade para problemas de controle ótimo com condições de contorno funcionais

Pós-graduação em Matemática - IBILCE

Aplicação da equação de Fokker-Planck no estudo de canais iônicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Weakly bound states of two- and three-boson systems in the crossover from two to three dimensions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Synchronization enhancement via an oscillatory bath in a network of self-excited cells

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Molecular model for hydrated biological tissues

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modeling the formation and propagation of desiccation cracks in soils

The problem of desiccation cracks in soils has received increasing attention in the last few years, in both experimental investigations and modeling. Experimental research has been mainly focused on the behavior of slurries subjected to drying in plates of different shapes, sizes and thickness. The main objectives of these studies were to learn about the process of crack formation under controlled environmental conditions, and also to better understand the effect of different factors (e.g. soil type, boundary conditions, soil thickness) on the morphology of the crack network. As for the numerical modeling, different approaches have been suggested lately to describe the behavior of drying cracks in soils. One aspect that it is still difficult to describe properly is the crack pattern observed in desiccated soils. This work presents a novel technique to model the behavior of drying soils. The crack patter observed in desiccation tests on circular plates are simulated with the main objective of predicting the effect of soil thickness on crack pattern. Good agreement between experimental results and model prediction are observed.

Variational and perturbative schemes for a spiked harmonic oscillator

A variational analysis of the spiked harmonic oscillator Hamiltonian operator - d2/dx2 + x2 + l(l + 1)/x2 + λ|x| -α, where α is a real positive parameter, is reported in this work. The formalism makes use of the functional space spanned by the solutions of the Schrödinger equation for the linear harmonic oscillator Hamiltonian supplemented by a Dirichlet boundary condition, and a standard procedure for diagonalizing symmetric matrices. The eigenvalues obtained by increasing the dimension of the basis set provide accurate approximations for the ground state energy of the model system, valid for positive and relatively large values of the coupling parameter λ. Additionally, a large coupling perturbative expansion is carried out and the contributions up to fourth-order to the ground state energy are explicitly evaluated. Numerical results are compared for the special case α = 5/2. © 1989 American Institute of Physics.

Effect of the parafunctional occlusal loading and crown height on stress distribution

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Magnetic-size effects in ultrathin layers

We study N-layer samples (N ≤ 10) for the Heisenberg model, with ferro- and antiferromagnetic exchange couplings, using a modified version of the Onsager reaction field approximation. The present scheme includes short-range spin-spin correlations, and allows for layer-dependent order parameters when free surface boundary conditions are imposed. The limits N = 1 (two dimensions) and N → ∞ (three dimensions) can be solved analytically, while systems with several layers have to be numerically calculated. We found no indication of a phase transition at finite temperature up to the sizes investigated (N = 10), the layered systems behaving essentially as two-dimensional. A phase transition is only obtained for the three-dimensional limit. © 1993.

Aplicação de um modelo numérico na otimização de fornos alimentícios usando o OpenFOAM®

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise Biomecânica em implantes com diferentes tipos de conexão: estudo pelo MEF-3D

The aim of this study was to evaluate the biomechanical behavior of different implant connection types, by means of three-dimensional finite element analysis. 3 Three-dimensional models were created with a graphic modeling software: SolidWorks 2006 and Rhinoceros 4.0, and InVesalius (CTI, São Paulo, Brasil), the bone was obtained by computerized tomography of a sagittal section of the molar region. The model was composed by bone block with an implant (4 x 10 mm) (Conexão Sistemas de Prótese, São Paulo), with different implant connections: external hex, internal hex and Morse-taper with the corresponding prosthetic component Ucla or Morse-taper abutment. The Three-dimensional models were transferred to finite element software Femap 10.0 (Siemens PLM Software Inc., CA, USA), to generate a mesh, boundary conditions and loading. An axial (200N) and oblique load (100N) was applied on the occlusal surface of the crowns. Analyses were performed using the finite element software NEiNastran 9.0 (Noran Engineering, Inc., USA) and transferred to the Femap 10.0 to obtain the results; after the results were visualized using von Mises stress maps and Maximum stress principal. The results showed the stress distribution was similar between models, with a little superiority of Morse-taper connection. It was concluded that: the three connection types were biomechanical viable; The Morse-taper connection presented the better internal stress distribution; there was not significant biomechanical differences on the bone.

The influence of the alveolar ridge shape on the stress distribution in a free-end saddle removable partial denture supported by implant

The alveolar ridge shape plays an important role in predicting the demand on the support tooth and alveolar bone in the removable partial denture (RPD) treatment. However, these data are unclear when the RPD is associated with implants. This study evaluated the influence of the alveolar ridge shape on the stress distribution of a free-end saddle RPD partially supported by implant using 2-dimensioanl finite element analysis (FEA). Four mathematical models (M) of a mandibular hemiarch simulating various alveolar ridge shapes (1-distal desceding, 2- concave, 3-horizontal and 4-distal ascending) were built. Tooth 33 was placed as the abutment. Two RPDs, one supported by tooth and fibromucosa (MB) and other one supported by tooth and implant (MC) were simulated. MA was the control (no RPD). The load (50N) were applied simultaneously on each cusp. Appropriate boundary conditions were assigned on the border of alveolar bone. Ansys 10.0 software was used to calculate the stress fields and the von Mises equivalent stress criteria (σvM) was applied to analyze the results. The distal ascending shape showed the highest σvM for cortical and medullar bone. The alveolar ridge shape had little effect on changing the σvM based on the same prosthesis, mainly around the abutment tooth.