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Phase-field modeling of fracture for quasi-brittle materials

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Underground Space 2019年第1期4卷 10-21页

作者： Jacinto Ulloa Patricio Rodríguez Cristóbal Samaniego Esteban Samaniego department of Civil Engineering Katholieke Universiteit LeuvenB-3001 LeuvenBelgium departamento de recursos hídricos y Ciencias Ambientales Universidad de CuencaCuenca 010151Ecuador Universidad de Cuenca Cuenca 010151Ecuador Institut für Kontinuumsmechanik Leibniz Universität HannoverHannover 30167Germany Inria Bordeaux-Sud-Ouest Research Center 200 Avenue de la Vieille TourTalence 33405France Facultad de Ingeniería Universidad de CuencaEcuador

This paper addresses the modeling of fracture in quasi-brittle materials using a phase-field approach to the description of crack *** the computational mechanics community,several studies have treated the issue of modeling fracture using phase *** of these studies have used an approach that implies the lack of a damage *** herein explore an alternative model that includes a damage threshold and study how it compares with the most popular *** formulation is systematically explained within a rigorous variational ***,we present the corresponding three-dimensional finite element discretization that leads to a straightforward numerical *** simulations in two dimensions and three dimensions are then *** results show that while an elastic stage and a damage threshold are ensured by the present model,good agreement with the results reported in the literature can be obtained,where such features are generally absent.

关键词： Quasi-brittle materials Fracture Variational formulation Phase fields Gradient damage

Assessment of Different WRF Configurations Performance for a Rain Event over Panama

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Atmospheric and Climate Sciences 2020年第3期10卷 280-297页

作者： Maibys Sierra-Lorenzo Arnoldo Bezanilla-Morlot Abel Dionisio Centella-Artola Anisbel León-Marcos Israel Borrajero-Montejo Adrián Luis Ferrer-hernández Jesús Leonel Salazar-Gaitán Alcely Lau-Melo Freddy Picado-Traña Joel Pérez-Fernández Center for Atmospheric Physics Meteorology Institute La Habana Cuba sección de recursos hídricos Autoridad del Canal de Panama Panama City Panama Dirección de hidrometeorología Empresa de Transmisión Eléctrica S.A. Panama City Panama Water Center for the humid Tropics of Latin America and the Caribbean Panama City Panama

A set of 15 combinations of microphysics and cumulus parameterizations for the WRF numerical model were tested in the forecast of a rain event on January 16 2018 over Panama. GPM satellite, upper air soundings and ground weather stations were used to evaluate the performance of each configuration. Different metrics were used to obtain the configurations that produced the best forecasts. The analysis showed a strong fluctuation of the diurnal precipitation cycle from one region to another. From the set of tests carried, BMJ with Morrison performed slightly above the other combinations in representing well the diurnal cycle for some domain areas, followed by Thom-Gr, WSM6-BMJ and WSM6-KF. While the experiments had a better performance forecasting over sea, they were not able to match the highest values of total precipitation. Regarding spatial rain distribution, all BMJ cumulus combinations showed the best skills mainly over the area comprising the Panama Canal while the others tended to overestimate the rain. Finally, most BMJ experiments showed the highest correlation factor and performed quite well representing the vertical profiles of relative humidity, temperature and wind.

关键词： Parameterization Microphysics WRF Rain

Use of Caffeine for the Evaluation of the Anthropic Influence over the Upper and Middle Iguaçu River Basins

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Journal of Water Resource and Protection 2022年第3期14卷 273-291页

作者： Bruna Scipioni Márcia Cristiane Kravetz Andrade Luis Otávio Miranda Peixoto Alinne Mizukawa Tais Cristina Filippe Júlio César Rodrigues de Azevedo Programa de Pós-Graduaç &atilde o em Engenharia de recursos hídricos e Ambiental Universidade Federal do Paraná Curitiba Brasil Universidade Tecnológica Federal do Paraná Curitiba Brasil

Many parameters are usually used as gauges to describe water quality worldwide, such as the concentrations of phosphorus, forms of nitrogen, dissolved oxygen (DO), among others. Though legislative limits for the concentrations of these substances are in place, such is not the case for caffeine. Caffeine is a pharmacologically active alkaloid, from the xanthine group, which can be used as a chemical tracer for anthropic influence over water resources. The objective of this study was to analyze the pollution indicators over the Igua?u River, one of the main rivers in Southern Brazil, through the examination of nutrients, DO and their correlations to caffeine. The water samples were collected from 10 sampling sites along the river course, unevenly spaced to better represent the different environmental scenarios present in its basin, extracted from 2014 to 2017. Caffeine was detected and quantified through high-efficiency liquid state chromatography. Results show that both nutrient and caffeine concentrations increased in intensely urbanized areas, specially from IG2 to IG5 sampling sites. Downstream from IG6 the contaminant concentrations decreased mainly due to higher river flows and lower population density. Caffeine was detected in 82% of the samples, indicating that most of the sampling sites were under anthropic influence.

关键词： Water Resources Water Quality Caffeine Urban Areas

Vadose Zone heterogeneity Effect on Unsaturated Water Flow Modeling at Meso-Scale

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Journal of Water Resource and Protection 2015年第4期7卷 353-368页

作者： Artur Paiva Coutinho Laurent Lassabatere Thierry Winiarski Jaime Joaquim da Silva Pereira Cabral Antonio Celso Dantas Antonino Rafael Angulo-Jaramillo LEhnA UMR 5023 CNRS ENTPE UCB-Lyon-1 Vaulx-en-Velin France Universidade Federal de Pernambuco Centro de Tecnologia e Geociências Programa de Pós Graduacao em Engenharia Civil/Tecnologia Ambiental e Recursos Hídricos Recife Brasil

The understanding of unsaturated flow in heterogeneous formations is a prerequisite to the understanding of pollutant transfer in the vadose zone and the proper management of infiltration basins settled over such heterogeneous formations. This study addresses the effect of lithological heterogeneity of a glaciofluvial deposit on flow in the vadose zone underneath an infiltration basin settled in the Lyon suburbs. The basin had already been the subject of several previous studies, some of which demonstrated the impact of soil heterogeneity. But all of them were only based on the sedimentological study of a trench and no study addressed the potential spatial variability of results due to the spatial variability of soil heterogeneity. In this study, we model flow in the vadose zone for several case studies, including drainage, water infiltration during a rainfall event, and a complete meteorological chronic. These calculations were conducted for several sections, previously characterized in the basin using GPR and sedimentological study and compared with a blank (homogeneous section). The results clearly show that heterogeneity impacts unsaturated flow and that these impacts depend upon the section considered. Some geometrical architectural and textural parameters were proposed to explain the spatial variability and effect of the soil heterogeneity on unsaturated flow, thus establishing the first step towards modeling unsaturated flow in the basin at the meso-scale.

关键词： Architectural and Structural Indicators Ground Penetration Radar numerical Modeling Preferential Flow Structural heterogeneity Unsaturated Flow

Recovery of Scenic Beauty of a Lake in Urban Park from Environmental Diagnosis and Implantation of Mitigating Measures

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Journal of Water Resource and Protection 2019年第5期11卷 595-605页

作者： Joã o Alexandre Saviolo Osti Clovis Ferreira Do Carmo Marcos Cerqueira Maria Teresa Duarte Giamas Ana Carolina Peixoto Cacilda Thais Janson Cacilda Thais Janson Pesquisador Associado ao Instituto de Pesca S&#227 o Paulo Brasil Professor Colaborador à Universidade Brasil Fernand&#243 polis Brasil Centro de Pesquisa em recursos hí dricos Instituto de Pesca APTA-SAA S&#227 o Paulo Brasil Pesquisador Cientí fico do Instituto de Pesca S&#227 o Paulo Brasil Aluna PIBIC de Iniciaç o Cientí fica do Instituto de Pesca S&#227 o Paulo Brasil

The city of S?o Paulo, state of S?o Paulo/Brazil, with about 12 million inhabitants is considered the largest city in Latin America. Just as in other large metropolises it is devoid of green areas, in this way it is of great socio-environmental importance of the preservation and maintenance of parks and green areas of the municipality. The Fernando Costa Park, known as the Parque da água Branca, is an urban park located in the central region of the Municipality of S?o Paulo, and has more than 79 thousand m2 of green area, in a total area of 137 thousand m2. Two lakes, populated predominantly with carp, are inserted in the Park, and are important components of the urban landscape and the patrimony of the city, present landscape function (scenic beauty) and are used to contemplate the environment and leisure of the population. The lakes due to the intense eutrophication process with uncontrolled growth of the phytoplankton presented blue-green coloration, with formations of lumps and foams, low transparency, bad smell and unpleasant visual aspect impairing the visitation of this place. In the first stage of the present research, an environmental diagnosis was carried out and the second stage involved elaboration and implementation of mitigating measures aiming at its restoration. The recovery proposal included the implementation of Artificial Floating Islands (IFAs) aiming at pollution control. After 60 days, it was possible to observe the efficiency of the Eichhornia crassipes populated islands showing that the methodology of phytoremediation was efficient in controlling the eutrophication of urban lakes, guaranteeing the recovery and conservation of the scenic beauty of these places.

关键词： Water Quality Eutrophication Pollution Landscape Ecology

Mean and Interannual Variability of Maize and Soybean in Brazil under Global Warming Conditions

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American Journal of Climate Change 2013年第4期2卷 237-253页

作者： Flávio Justino Evandro Chaves Oliveira Rafael de Avila Rodrigues Paulo henrique Lopes Goncalves Paulo Jorge Oliveira Ponte Souza Frode Stordal José Marengo Thieres G.da Silva Rafael Coll delgado Douglas da Silva Lindemann Luiz Claudio Costa departamento de Engenharia Agrícola Universidade Federal de ViçosaVicosaBrazil Universidade Federal Rural da Amazônia Instituto Sócio-Ambiental e dos Recursos HídricosBelémBrazil department of Geosciences University of OsloOsloNorway Instituto nacional de Pesquisas Espaciais Cachoeira PaulistaBrazil Universidade Federal Rural de Pernambuco Unidade Academica de Serra TalhadaSerra TalhadaBrazil Universidade Federal Rural do Rio de Janeiro Instituto de Florestas/Departamento de Ciencias AmbientaisSeropédicaBrazil

Brazil is responsible for 27% of the world production of soybeans and 7% of maize. Mato Grosso and Para states in Brazil are among the largest producer. The viability to the cultivation of maize (Zea mays) and soybeans (Glycine max), for future climate scenarios (2070-2100, GhG) is evaluated based on crop modeling (DSSAT) forced by observational data and regional climate simulations (hadRM3). The results demonstrated that a substantial reduction in the yield in particular for maize may be expected for the end of the 21st century. Distinct results are found for soybeans. By applying the A2 climate changes scenario, soybean yield rises by up top 60% assuming optimum soil treatment and no water stress. however, by analyzing the inter-annual variability of crop yields for both maize and soybean, could be demonstrated larger year-to-year fluctuations under greenhouse warming conditions as compared to current conditions, leading to very low productivity by the end of the 21st century. Therefore, these Brazilian states do not appear to be economically suitable for a future cultivation of maize and soybeans. Improved adaptation measures and soil management may however partially alleviate the negative climate change effect.

关键词： Climate Changes Soybeans Maize

Effect of climate and altitude on plant community composition and richness in Brazilian inselbergs

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Journal of Mountain Science 2020年第8期17卷 1931-1941页

作者： herval Vieira PInTO-JUnIOR Pedro Manuel VILLA Luis Fernando Tavares de MEnEZES Miriam Cristina Alvarez PEREIRA Universidade Federal de Vigosa Department of Plant BiologyLaboratory of Ecology and Evolution of Plants36570-900Vicosa-MGBrazil Universidade Federal de Vigosa Department of Forest EngineeringLaboratory of Forest Restoration36570-900Vicosa-MGBrazil Universidade Federal do Espirito Santo Department of Agrarian and Biological SciencesLaboratory of Ecology of Restinga and Mata Atlantica29932-900Sao Mateus-ESBrazil Universidade Federal do Espirito Santo Department of Biology29500-000Alegre-ESBrazil

Plant communities are shaped by multiple factors along environmental gradients;however,studies are limited on how environmental filtering drives community composition and species richness on tropical *** evaluate the influence of altitude and climatic variables related to temperature and precipitation on plant community composition and species richness on Brazilian *** assume as a premise that both climate and altitude would induce changes on plant community composition and species richness at the local *** used plant inventory data from 370 sampling units across four inselberg sites in the Atlantic Forest of Espírito Santo State,south-eastern *** tested the univariate and multivariate effects of altitude and climate variables on community composition and species richness with multiple *** in species richness between inselbergs were evaluated using sample-based data to estimate rarefaction and extrapolation *** addition,differences in species composition and taxonomic beta diversity were examined via novel frequency-based metrics.A contrasting climate pattern was observed between the inselberg sites,with south sites being wet compared to the dry conditions found in northern *** richness by rarefaction showed a similar pattern within regional sites;however,there were marked differences between *** richness and beta diversity showed significant differences among sites,with higher values in southern sites than in northern *** a multi-model comparison between inselberg sites,altitude significantly influenced community composition and species richness and explained more variance than climate *** finding suggested that climate could act to some extent on these tropical inselbergs;however,altitude was a better predictor of plant community composition and species richness at the local level.

关键词： Atlantic Forest Biome Beta diversity Abiotic filtering Climate models Environmental filtering Latitudinal gradient