A preconditioner for the Schur complement matrix

A preconditioner for iterative solution of the interface problem in Schur Complement Domain Decomposition Methods is presented. This preconditioner is based on solving a global problem in a narrow strip around the interface. It requires much less memory and computing time than classical Neumann–Neumann preconditioner and its variants, and handles correctly the flux splitting among subdomains that share the interface. The aim of this work is to present a theoretical basis (regarding the behavior of Schur complement matrix spectra) and some simple numerical experiments conducted in a sequential environment as a motivation for adopting the proposed preconditioner. Efficiency, scalability, and implementation details on a production parallel finite element code [Sonzogni V, Yommi A, Nigro N, Storti M. A parallel finite element program on a Beowulf cluster. Adv Eng Software 2002;33(7–10):427–43; Storti M, Nigro N, Paz R, Dalcín L. PETSc-FEM: a general purpose, parallel, multi-physics FEM program, 1999–2006] can be found in works [Paz R, Storti M. An interface strip preconditioner for domain decomposition methods: application to hydrology. Int J Numer Methods Eng 2005;62(13):1873–94; Paz R, Nigro N, Storti M. On the efficiency and quality of numerical solutions in cfd problems using the interface strip preconditioner for domain decomposition methods. Int J Numer Methods Fluids, in press].Fil: Storti, Mario Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Dalcin, Lisandro Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Paz, Rodrigo Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Yommi, Alejandra Karina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Sonzogni, Victorio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Nigro, Norberto Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Numerical simulation of the flow around the ahmed vehicle model

The unsteady flow around the Ahmed vehicle model is numerically solved for a Reynolds number of 4.25 million based on the model length. A viscous and incompressible fluid flow of Newtonian type governed by the Navier-Stokes equations is assumed. A Large Eddy Simulation (LES) technique is applied together with the Smagorinsky model as Subgrid Scale Modeling (SGM) and a slightly modified van Driest near-wall damping. A monolithic computational code based on the finite element method is used, with linear basis functions for both pressure and velocity fields, stabilized by means of the Streamline Upwind Petrov-Galerkin (SUPG) scheme combined with the Pressure Stabilizing Petrov- Galerkin (PSPG) one. Parallel computing on a Beowulf cluster with a domain decomposition technique for solving the algebraic system is used. The flow analysis is focused on the near-wake region, where the coherent macro structures are estimated through the second invariant of the velocity gradient (or Q-criterion) applied on the time-average flow. It is verified that the topological features of the timeaverage flow are independent of the averaging time T and grid-size.Fil: Franck, Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina. Universidad Tecnologica Nacional; ArgentinaFil: Nigro, Norberto Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Storti, Mario Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: D'elia, Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Reduced model for the thermo-fluid dynamic analysis of a power transformer radiator working in ONAF mode

This work introduces an extension of the semi-analytical reduced model presented in G. Ríos Rodriguez et.al., App Thermal Eng, 112:1271–1280 (2016); with the aim of analyzing the thermo-fluid dynamic behavior of a power transformer radiator working in ONAF (Oil Natural Air Forced) mode, considering vertical blowing of the fans. The objective of this research paper is the development of a numerical tool to be used during the design process of power transformers in order to obtain more detailed information about the radiators performance, either they are working in ONAF or ONAN (Oil Natural Air Natural) mode. Since it is observed both in the experimental measurements and in the numerical simulations that not all the radiator panels are blown by a single fan, the reduced model here presented considers a mixed situation wherein the heat is removed by natural convection in a fraction of the radiator while in the rest the heat is removed by forced convection. As a consequence, besides adding to the set of conservation equations introduced in G. Ríos Rodriguez et.al., App Thermal Eng, 112:1271– 1280 (2016); those corresponding to the momentum and energy balance for considering forced heat convection transfer, there appears the need of introducing additional equations for coupling the natural and forced heat convection transfer models. The reduced model developed in this work is applied to estimate different characteristic parameters of a power transformer radiator working in ONAF mode, like the oil flow rate, dissipated power, outlet and inlet oil temperatures, among others. The computed results are compared to those obtained by CFD simulations and experimental measurements carried out on an ad-hoc workbench for validation purposes. It is found that the reduced model reproduces with acceptable accuracy the values of the most important design variables at a very low computation cost. In this manner, it can be considered as a reliable and valuable tool in the design of power transformers, allowing to carry out parametric studies.Publicado en: Mecánica Computacional vol. XXXV, no. 4Facultad de Ingenierí

Reduced model for the thermo-fluid dynamic analysis of a power transformer radiator working in ONAF mode

This work introduces an extension of the semi-analytical reduced model presented in G. Ríos Rodriguez et.al., App Thermal Eng, 112:1271–1280 (2016); with the aim of analyzing the thermo-fluid dynamic behavior of a power transformer radiator working in ONAF (Oil Natural Air Forced) mode, considering vertical blowing of the fans. The objective of this research paper is the development of a numerical tool to be used during the design process of power transformers in order to obtain more detailed information about the radiators performance, either they are working in ONAF or ONAN (Oil Natural Air Natural) mode. Since it is observed both in the experimental measurements and in the numerical simulations that not all the radiator panels are blown by a single fan, the reduced model here presented considers a mixed situation wherein the heat is removed by natural convection in a fraction of the radiator while in the rest the heat is removed by forced convection. As a consequence, besides adding to the set of conservation equations introduced in G. Ríos Rodriguez et.al., App Thermal Eng, 112:1271– 1280 (2016); those corresponding to the momentum and energy balance for considering forced heat convection transfer, there appears the need of introducing additional equations for coupling the natural and forced heat convection transfer models. The reduced model developed in this work is applied to estimate different characteristic parameters of a power transformer radiator working in ONAF mode, like the oil flow rate, dissipated power, outlet and inlet oil temperatures, among others. The computed results are compared to those obtained by CFD simulations and experimental measurements carried out on an ad-hoc workbench for validation purposes. It is found that the reduced model reproduces with acceptable accuracy the values of the most important design variables at a very low computation cost. In this manner, it can be considered as a reliable and valuable tool in the design of power transformers, allowing to carry out parametric studies.Publicado en: Mecánica Computacional vol. XXXV, no. 4Facultad de Ingenierí

UM ESTUDO BIBLIOMÉTRICO DA ÚLTIMA DÉCADA NA WEB OF SCIENCE: PESQUISAS ENVOLVENDO REMANUFATURA E TEORIA GERAL DOS SISTEMAS

Diante do esgotamento dos recursos naturais e a poluição do meio ambiente estimulou-se a discussão sobre os atuais padrões de consumo e o modo como as instituições vêm desenvolvendo suas atividades. Uma das propostas é pensar no reaproveitamento de produtos já criados, para isso, a manufatura surge como um processo que traz vantagens ambientais e econômicas. Sendo assim, este artigo tem como objetivo investigar os estudos propostos sobre remanufatura e teoria geral dos sistemas, já que convivemos com diferentes sistemas no nosso cotidiano, nos últimos dez anos na Web Of Science. Para isso, adotou uma análise bibliométrica. A análise das publicações na base de dados Web of Science, resultou em 2212 artigos e constatou-se que a quantidade de estudos acerca da temática no período compreendido entre 2011 e 2020 vêm aumentando gradativamente. Quanto ao número de artigos por países, os Estados Unidos lideram o ranking de publicações, seguidos da China. Dentre os tipos de produções, o formato de artigo é o mais escolhido entre os pesquisadores

Recría de vaquillas de reposición en ambientes malezal y campos de loma

En la siguiente publicación se brinda información experimental y de validación sobre manejo para acortar la edad de entore para la zona de malezales y campos de loma. De esta manera, el productor podrá adop¬tar, con mayor certeza, aquellas técnicas que se adapten a su sistema y que mejoraran su producción e ingresos.EEA MercedesFil: Beccaria, Mauricio Daniel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mercedes. Agencia de Extensión Rural Curuzú Cuatiá; Argentina.Fil: Preisz, Víctor Hernán. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mercedes. Agencia de Extensión Rural Curuzú Cuatiá; Argentina.Fil: Storti, Marcelo Gabriel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mercedes. Agencia de Extensión Rural Santo Tomé; Argentina.Fil: Schiro, Fernando Danilo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mercedes. Agencia de Extensión Rural Virasoro; Argentina.Fil: Uguet Vaquer Piloni, Jaime Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mercedes. Agencia de Extensión Rural Virasoro; Argentina.Fil: Rivero, Luis Domingo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mercedes; Argentina

Causas que afectan la adopción de tecnología en la ganadería bovina para carne de la provincia de Corrientes: enfoque cualitativo

El presente trabajo de investigación, realizado con criterio multienfoque e interdisciplinario, brinda un diagnóstico de la percepción de los productores ganaderos de Corrientes y de las razones que subyacen a la toma de decisión en adopción de tecnologías, sean éstas de proceso o de insumo. Se destaca que es posible realizar estudios de adopción mediante enfoque cualitativo, contemplando un número considerable de tecnologíasCentro de Investigación en Ciencias Políticas, Económicas y SocialesFil: Giancola, Silvana Inés. Instituto Nacional de Tecnología Agropecuaria (INTA). Centro de Investigación en Ciencias Políticas, Económicas y Sociales. Instituto de Economía y Sociología; ArgentinaFil: Calvo, Sonia Cecilia. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Sampedro, Daniel Horacio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mercedes; ArgentinaFil: Marastoni, Ariel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mercedes; ArgentinaFil: Ponce, Valeria. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mercedes; ArgentinaFil: Di Giano, Silvina. Investigadora independiente; ArgentinaFil: Storti, Marcelo Gabriel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mercedes; Argentin

Impact of a twelve-year rotavirus vaccine program on acute diarrhea mortality and hospitalization in Brazil

Background Monitoring the impact of vaccine programs is necessary to identify changes in vaccine efficacy. We report the impact of the 12-year rotavirus vaccine program on diarrhea mortality and hospitalizations and their correlation to socioeconomic indicators. Methods this ecological study describes diarrhea hospitalizations and deaths from 2006 to 2018 in Brazil and correlates rotavirus vaccine coverage, hospitalizations and deaths to socioeconomic indicators and social vulnerability index (SVI) by state and region. Hospitalizations, deaths, and vaccine coverage trends were analyzed using Joinpoint regression models. Associations between hospitalizations, mortality and rotavirus vaccination coverage and socioeconomic and SVI indicators were established using Ordinary Least Square regressions. Results Rotavirus vaccine coverage remained stable between 2006 and 2018 (annual percentage changes (APC) [95%CI]: 4.4% [−0.3%, 9.2%]). Diarrhea hospitalization rates decreased 52.5% (−5.7% [−7.5%, −3.8%]), from 68.4 to 32.5 hospitalizations per 10,000 children <5 years-old between 2006 and 2018, with significant decreases in diarrhea mortality (−9.8% [−11.2%, −8.5%]). The Northeast region experienced the largest reductions (−13.9% [−15.7%, −12.2%]). Vaccination coverage and diarrhea-mortality were inversely correlated with the SVI. Conclusion The burden of childhood diarrhea has decreased over an extended period. States with high SVI, but high vaccination coverage had the largest reductions in hospitalizations and deaths

COMPARISON BETWEEN FOUR USUAL METHODS OF IDENTIFICATION OF Candida SPECIES

SUMMARY Infection by Candidaspp. is associated with high mortality rates, especially when treatment is not appropriate and/or not immediate. Therefore, it is necessary to correctly identify the genus and species of Candida. The aim of this study was to compare the identification of 89 samples of Candida spp. by the manual methods germ tube test, auxanogram and chromogenic medium in relation to the ID 32C automated method. The concordances between the methods in ascending order, measured by the Kappa index were: ID 32C with CHROMagar Candida(κ = 0.38), ID 32C with auxanogram (κ = 0.59) and ID 32C with germ tube (κ = 0.9). One of the species identified in this study was C. tropicalis,which demonstrated a sensitivity of 46.2%, a specificity of 95.2%, PPV of 80%, NPV of 81.1%, and an accuracy of 80.9% in tests performed with CHROMagar Candida;and a sensitivity of 76.9%, a specificity of 96.8%, PPV of 90.9%, NPV of 91%, and an accuracy of 91% in the auxanogram tests. Therefore, it is necessary to know the advantages and limitations of methods to choose the best combination between them for a fast and correct identification of Candidaspecies