José L. D. Alves

Simple zero thickness kinematically consistent interface elements

Abstract Interface finite elements have been used in many geotechnical and engineering applications. Essentially, these elements must allow relative displacements between two bodies in contact, or separated by a thin material layer. Frequently, interface elements behave as linear elastic bodies up to a limiting stress state. This linear behavior of interfaces is very important, because it will establish when the slip and/or separation occurs, causing stress redistribution over the mesh. In this paper, the mechanical behavior of interface elements is discussed. It is shown that the kinematic inconsistency pointed by Kaliakin and Li [Comp. Geotech. 17 (1995) 225] for the element proposed by Goodman et al. [ASCE J. Soil Mech. Fdns. Div. 99 (1968) 637] also occurs for other interface models, and new interface elements for 2D and 3D analyses without kinematic inconsistencies are proposed.

Comparison of lanczos and conjugate gradients for the element-by-element solution of finite element equations on the ibm 3090 vector computer

Abstract Experiences in the iterative solution of large systems of finite element equations on the IBM 3090 600 E/6VF vector computer are presented. The iterative drivers are the preconditioned conjugate gradient method and Lanczos algorithm. The algorithms are implemented utilizing the element-by-element scheme. The numerical experiments show the computer effectiveness of the present implementation, favouring the conjugate gradient algorithms.

Conjugate gradient solution of finite element equations on the IBM 3090 vector computer utilizing polynomial preconditionings

Abstract This paper presents the conjugate gradient solution of large finite element systems of equations on the IBM 3090/VF vector computer utilizing polynomial preconditionings. These preconditionings are based on Saads least square polynomials applied to a scaled system of equations. Therefore, for very ill-conditioned systems the required amount of computation is reduced. The matrix-vector operations needed in the conjugate gradient iterations, as well as in the construction of the preconditioners, are computed at element level using an element-by-element solution scheme. Reordering the finite element mesh by a colouring algorithm and stacking the finite elements for vector processing, the matrix operations are fully vectorized. To best explore the high-speed of the IBM 3090 Vector Facility, the Basic Linear Algebra Subprograms available in the ESSL vector library were invoked in the test runs. The numerical experiments provide the necessary support to efficiently use polynomial preconditionings in finite element applications.

A study of implementation schemes for vectorized sparse EBE matrix-vector multiplication

Abstract A study of implementation schemes for vectorized sparse element-by-element (EBE) matrix-vector multiplication used in the iterative equation solving of finite element problems is presented. The Hughes, Ferencz and Hallquist scheme and a variation are compared with Torigakis approach. Computer timing and required memory for each scheme on the IBM 3090/VF vector computer regarding the analysis of large scale three-dimensional solid mechanics problems are presented and results compared.

Estudo da influência das anomalias da TSM do Atlântico Sul extratropical na região da Confluência Brasil-Malvinas no regime hidrometeorológico de verão do Sul e Sudeste do Brasil

This study analyses the influence of the extratropical South Atlantic sea surface temperature (SST) anomalies in the Southern and Southeastern Brazilian hydrometeorological pattern. The Brazil-Malvinas Confluence (BMC) is one of the most important South Atlantic Ocean features. This region is characterized by a strong thermal front formed by the confluence between the warm waters transported by the Brazil Current (BC) and the cold waters carried by the Malvinas Current (MC). The knowledgement of its dynamics could represent an important advance to understand its connection with locally and remotely generated ocean and atmospheric processes. This investigation is made with computational modeling using a Community Atmosphere Model (CAM 2.01). The spatial and time SST anomalies were numerically generated inside the model code in such a way to reproduce the summer 2005 event. Significant changes were observed in this experiment in the vertical atmospheric circulation pattern. The precipitation over South Brazil region decreased and more favorable conditions to the South Atlantic Convergence Zone (SACZ) formation appeared over the northern part of the Southeastern Brazil region. These model generated patterns were similar to those observed during the summer 2005, especially the precipitation anomalies results.

Edge-based interface elements for solution of three-dimensional geomechanical problems

An edge-based three-dimensional interface element for simulation of joints, faults and other discontinuities present in several geomechanical applications is proposed. Edge-based data structures are used to improve computational efficiency of Inexact Newton methods for solving finite element nonlinear problems on unstructured meshes. Numerical experiments in the solution of three-dimensional problems in cache based and vector processors have shown that memory and computer time are reduced.

Parallel Edge-Based Finite Element Techniques for Nonlinear Solid Mechanics

Parallel edge-based data structures are used to improve computational efficiency of Inexact Newton methods for solving finite element nonlinear solid mechanics problems on unstructured meshes composed by tetrahedra or hexaedra. We found that for tetrahedral meshes, the use of edge-based data structures reduce memory requirements to hold the stiffness matrix by a factor of 7, and the number of floating point operations to compute the matrix-vector product needed in the iterative driver of the Inexact Newton method by a factor of 5. For hexahedral meshes the reduction factors are respectively 2 and 3.

Tradução e validação da adaptação para o exercício do Perceived Motivational Climate Sport Questionnaire

O objetivo principal do estudo e a traducao e validacao da versao portuguesa da adaptacao ao exercicio do Perceived Motivational Climate in Sport Questionnaire (PMCSQ), com recurso a analise fatorial exploratoria (AFE) e confirmatoria (AFC), realizadas com dois grupos independentes de praticantes de exercicio em ginasios, de ambos os generos e com idades compreendidas entre os 14 e os 64 anos. Na AFE os resultados revelam uma estrutura que explica 52% da variância dos resultados, pesos fatoriais entre 0.63 e 0.80, e uma boa consistencia interna (αMestria=0.78; αPerformance=0.74). Na AFC os resultados indicam um excelente ajustamento do modelo: S-Bχ2=40.6; df=34; p=0.20; S-Bχ2/df=1.19; SRMR=0.03; NNFI=0.98; CFI=0.99; RMSEA=0.02; 90% IC RMSEA=0.00-0.05, uma consistencia interna razoavel (αMestria=0.74; αPerformance=0.75), e pesos fatoriais entre 0.50 e 0.79, o que nos leva a concluir que a versao Portuguesa da adaptacao do PMCSQ ao exercicio pode ser utilizada na avaliacao do clima motivacional no exercicio.The main purpose of this study is to present the results of translation and validation of the Portuguese version of Perceived Motivational Climate in Sport Questionnaire (PMCSQ) adaptation to exercise, through exploratory (EFA) and confirmatory (CFA) factor analysis, performed with two independent groups of participants, all exercisers in private fitness clubs, of both sexes, and aged between 14 and 64 years old. The EFA results reveal a structure explaining 52% of total variance, with factor loadings ranged from 0.63 to 0.80, and reasonable reliability (αMastery=0.78; αPerformance=0.74). The AFC results showed an excellent model fit to data: S-Bχ2=40.6; df=34; p=0.20; S-Bχ2/df=1.19; SRMR=0.03; NNFI=0.98; CFI=0.99; RMSEA=0.02; 90% IC RMSEA=0.00-0.05, an acceptable reliability (αMastery=0.74; αPerformance=0.75), and factor loadings ranged from 0.50 to 0.79, which leads us to conclude that Portuguese version of PMCSQ adaptation to exercise can be used to measure motivational climate in exercise.

Tradução e Validação da Versão Portuguesa da Goal Orientation in Exercise Scale (GOESp)

O objectivo deste estudo e a apresentacao dos resultados da traducao e validacao da versao Portuguesa da Goal Orientation in Exercise Scale (GOES), com recurso a analise factorial exploratoria (AFE) e confirmatoria (AFC), realizadas com dois grupos de praticantes de exercicio em ginasios, de ambos os generos e com idades entre os 15 e os 61 anos. Os resultados da AFE revelam uma estrutura factorial que explica 61% da variância dos resultados, pesos factoriais entre 0,63 e 0,86, e uma boa consistencia interna (αEgo=0,91; αTarefa=0,74). No entanto, os resultados da AFC indicam que o modelo nao se ajustou aos dados: S-Bχ2=154,59; gl=34; p=0,000; S-Bχ2/gl=4,55; SRMR=0,06; NNFI=0,87; CFI=0,90; RMSEA=0,10; 90% IC RMSEA=0,09-0,12, e so apresentou indices aceitaveis de ajustamento apos a sua re-especificacao, que conduziu a eliminacao de um item. Assim, aconselha-se alguma prudencia na sua utilizacao, e a realizacao de mais estudos sobre a sua validade.

Climate downscaling over South America for 1971–2000: application in SMAP rainfall-runoff model for Grande River Basin

This paper aims to validate inflow simulations concerning the present-day climate at Água Vermelha Hydroelectric Plant (AVHP—located on the Grande River Basin) based on the Soil Moisture Accounting Procedure (SMAP) hydrological model. In order to provide rainfall data to the SMAP model, the RegCM regional climate model was also used working with boundary conditions from the MIROC model. Initially, present-day climate simulation performed by RegCM model was analyzed. It was found that, in terms of rainfall, the model was able to simulate the main patterns observed over South America. A bias correction technique was also used and it was essential to reduce mistakes related to rainfall simulation. Comparison between rainfall simulations from RegCM and MIROC showed improvements when the dynamical downscaling was performed. Then, SMAP, a rainfall-runoff hydrological model, was used to simulate inflows at Água Vermelha Hydroelectric Plant. After calibration with observed rainfall, SMAP simulations were evaluated in two different periods from the one used in calibration. During calibration, SMAP captures the inflow variability observed at AVHP. During validation periods, the hydrological model obtained better results and statistics with observed rainfall. However, in spite of some discrepancies, the use of simulated rainfall without bias correction captured the interannual flow variability. However, the use of bias removal in the simulated rainfall performed by RegCM brought significant improvements to the simulation of natural inflows performed by SMAP. Not only the curve of simulated inflow became more similar to the observed inflow, but also the statistics improved their values. Improvements were also noticed in the inflow simulation when the rainfall was provided by the regional climate model compared to the global model. In general, results obtained so far prove that there was an added value in rainfall when regional climate model was compared to global climate model and that data from regional models must be bias-corrected so as to improve their results.