Influência dos parâmetros e critérios dos modelos de dano coesivo na previsão da resistência ao impacto de juntas adesivas

A ligação adesiva é um processo de união permanente entre os componentes de uma estrutura que utiliza um adesivo para unir os componentes após a sua cura. Este tipo de ligação, teoricamente, deveria ser pelo menos tão resistente como o material ligado. As juntas adesivas têm vindo cada vez a ser mais usadas em diversas aplicações. Para isso é importante conhecer o seu comportamento quando submetidos a cargas estáticas ou de impacto. Para a realização destes estudos são necessários software que utilizam o Método dos Elementos Finitos. Neste sentido surgem os modelos de dano coesivo que têm vindo a ser utilizados para prever a resistência das juntas adesivas e simular o crescimento de dano em estruturas após introdução das leis coesivas. Este trabalho estuda as diferentes condições de Modelo de Dano Coesivo usadas para modelar uma camada adesiva numa junta de sobreposição simples, sujeita a uma carga de impacto. Os resultados numéricos são validados com recurso a um trabalho prévio experimental. Neste estudo considerou-se quatro comprimentos de ligação (12,5; 25; 37,5 e 50 mm) e três tipos de adesivos (Sikaforce® 7752 – dúctil, Araldite® AV138 – frágil e XNR6852 – dúctil) em juntas de sobreposição simples. Os vários parâmetros de estudo foram: rigidez elástica da lei coesiva, desacoplamento dos modos de carregamento com lei triangular, forma da lei coesiva, critérios de iniciação de dano e critério de propagação de dano. Esta análise permitiu concluir que os Modelos de Dano Coesivo são uma técnica fiável para a previsão da resistência da junta adesiva, desde que as condições de modelação sejam corretamente selecionadas. Por outro lado, a análise numérica realizada permitiu compreender em detalhe qual a influência dos critérios usados nos modelos coesivos nos resultados obtidos nas simulações.Adhesive bonding is a process of permanent bonding between the components of a structure that uses an adhesive to join the components after curing. This type of connection, theoretically, should be at least as strong as the bonded material. Adhesive joints have increasingly been used in many applications. For this it is important to know their behavior when subjected to static or impact loads. To carry out these studies, software using the Finite Element Method is required. In this sense, cohesive zone models have been used to predict the strength of adhesive joints and to simulate the growth of damage in structures after definition of the cohesive laws. This work studies the different Cohesive Zone Model conditions used to model an adhesive layer in a single-lap joint, subjected to impact loading. The numerical results are validated using previous experimental work. In this study four bonding lengths (12.5; 25; 37.5 and 50 mm) and three types of adhesives (Sikaforce® 7752 - ductile, Araldite® AV138 - brittle and XNR6852 - ductile) were considered in single-lap joints. The various parameters of study were: elastic stiffness of cohesive law, decoupling of loading modes with triangular law, cohesive law shape, damage initiation criteria and damage propagation criterion. This analysis allowed to conclude that Cohesive Zone Models are a reliable technique to predict the adhesive joint strength, provided that the modeling conditions are correctly selected. On the other hand, the numerical analysis made it possible to understand in detail the influence of the criteria used in the cohesive models in the results obtained in the simulations

Plano de ação para a energia sustentável e clima do concelho de Viseu

Tese de mestrado integrado, Engenharia da Energia e do Ambiente, Universidade de Lisboa, Faculdade de Ciências, 2019A transição energética, que visa um consumo de energia mais eficiente e sustentável, é imprescindível no combate às Alterações Climáticas e só é possível se houver iniciativa da parte dos órgãos governamentais. O Pacto de Autarcas, lançado em 2008 pela Comissão Europeia, incentiva as Autarquias a comprometerem-se voluntariamente a reduzir as emissões de gases com efeito de estufa em 40% até 2030. O Município de Viseu, em Portugal, foi um dos aderentes, comprometendo-se a realizar um Plano de Ação para a Energia Sustentável e Clima ou, em língua inglesa, Sustainable Energy and Climate Action Plan (SECAP), que se apresenta e discute nesta dissertação. Para que se cumpra o objetivo traçado, é necessário adotar medidas de redução do consumo de energia e, em simultâneo, aumentar a penetração de fontes de energias renováveis, o que conduz a uma mitigação das emissões de gases de efeito de estufa. Este esforço deve ser feito tanto a nível público como privado, abrangendo diretamente a autarquia, mas também os setores da indústria, transportes, residencial e terciário. Para este efeito, é necessário construir a matriz energética e a matriz de gases com efeito de estufa, de forma a caracterizar detalhadamente os consumos no Concelho de Viseu, para que se possa atuar de forma informada e consciente. Apresenta-se também a matriz prospetiva do Concelho, onde se faz uma projeção dos hábitos de consumo para o futuro abrangido pelo SECAP (horizonte 2030). No ano 2000, ano de referência adotado no SECAP, registou-se um consumo energético de 1 817 GWh, o que se traduz numa emissão de 502 milhares de toneladas de CO2eq. São propostas 28 medidas de mitigação que implicam uma redução de 41,6% das emissões face ao ano de referência, representando aproximadamente 659 GWh de energia final e 209 milhares de toneladas de CO2eq.Energy transition aims at reaching a more efficient and sustainable energy consumption, which is crucial in the fight on Climate Change, and only possible if initiative from governmental agencies takes place. The Covenant of Mayors was started in 2008 by the European Commission, which encourages local governments to voluntarily compromise to reduce greenhouse gas emissions in 40% by 2030. The Municipality of Viseu, Portugal, adhered in 2010, compromising to establish a Sustainable Energy Action Plan (SECAP), which is presented and discussed in this dissertation. In order to comply with the set objective, it is necessary to adopt measures that reduce energy consumption, as well as increase production of electricity through renewable energy sources. This effort should be made on both public and private levels, including the municipality itself, but also industry, transportation, residential and commerce and services sectors. Thus, it is necessary to build a baseline emission inventory in order to characterize, in detail, the energy consumption and greenhouse gas emissions in the County, so that well informed and conscious decisions can be made. A prospective study of the Municipality is presented, with the projection of the consumption habits of the population in the future (horizon 2030). In the year 2000, the year of reference for the SECAP, an energy consumption of 1 817 GWh was registered, which represents an emission of 502 thousand tons of CO2eq. A total of 28 mitigation measures were proposed, implicating a reduction of 41,6% of emissions, which represents a reduction of approximately 659 GWh of energy consumed and 209 thousand tons of CO2eq emitted

Social Housing in Porto Alegre - A retrospective studying about the municipal public policies collated with the implementation of Minha Casa Minha Vida Program

The Public Policies in Social Housing in Brazil had been significantly increased with the implementation of My House My Life (MVMC) Program in a federal level, since March 2009. The quantitative results in the production of dwellings were substantial however, its necessary a critical Analysis about the Program with regard to city production and planning. The objective of this article is to establish a comparison with policies until then adopted, focusing in Porto Alegre city, to verify if the subsequent centralization of the resources in the federal level had been the best way to the desired promotion of most inclusive, participative and democratic Cities

Comparative leaf anatomy of four species of Bromelioideae (Bromeliaceae) occurring in the Atlantic Forest, Brazil

Bromeliaceae, comprising 3172 species, is one of the most important families of the Brazilian Atlantic Forest owing to its high degree of endemism and occurrence in different habitats. The subfamily Bromelioideae is the most representative of Bromeliaceae and the best represented in the state of Minas Gerais, Brazil, with 120 species. The objective of this study is to compare the leaf anatomy of four species found in two areas of the Atlantic Forest: Serra do Brigadeiro State Park, Minas Gerais, Brazil ( Wawra and (Baker) Leme) and a forest fragment located within Bom Sucesso Farm, Viçosa, Minas Gerais, Brazil ( E. Morren and Bertol.), relating environmental characteristics to the habit. Leaf samples were studied using light and scanning electron microscopy and histochemical tests with Sudan, phloroglucinol, and ruthenium red stains. Leaves of and showed several adaptations to the epiphytic habit, including scales on both surfaces, thickened epidermal cell walls, presence of silica bodies, hypodermis with sclerified cells, water-storing tissue (hydrenchyma), and air channels formed by stellate cells in the chlorenchyma. The epiphytic species and the terrestrial species have similar overall structure, including a well-developed parenchyma and extravascular fiber groups. Leaves of the terrestrial species and the epiphytic species also show structural similarities, such as lack of extravascular fibers and less developed parenchyma. Similar characteristics in species from different habitats may either reflect microclimatic conditions under which these species occur or genetically fixed characteristics.Les Bromeliaceae, comprenant 3172 espèces, constituent une des familles les plus importantes de la forêt atlantique brésilienne par son fort degré d'endémisme et par sa présence dans différents habitats. La sous-famille des Bromelioideae, la plus représentative des Bromeliaceae, est la mieux représentée dans l'état de Minas Gerais, au Brésil, avec 120 espèces. L'objectif de l'étude consiste à comparer l'anatomie foliaire de quatre espèces trouvées dans deux régions de la forêt atlantique : parc de l'état « Serra do Brigadeiro », MG, Brésil ( Quesnelia strobilispica Wawra et Wittrockia gigantea (Baker) Leme), et un fragment forestier localisé sur la ferme « Bom Sucesso », Viçosa, MG, Brésil ( Billbergia euphemiae E. Morren et Bromelia antiacantha Bertol.), en reliant les caractéristiques environnementales avec l'habitat. Les auteurs ont étudié les feuilles à l'aide de la microscopie photonique et électronique par balayage, ainsi que des colorations au Sudan, phloroglucinol, et rouge de ruthénium. Les feuilles du B. euphemiae et du W. gigantea montrent plusieurs adaptations à l'habitat épiphyte, incluant des écailles sur les deux surfaces, des parois cellulaires épaissies, la présence de corps siliceux, un hypoderme avec des cellules sclérifiées, des tissus accumulateurs d'eau (hydranchymes) et des canaux aérifères formés par des cellules stellées, dans le chlorenchyme. L'espèce épiphyte, B. euphemiae, et l'espèce terrestre, Q. strobilispica, possèdent en général des structures similaires, incluant un parenchyme bien développé et des groupes de fibres extra-vasculaires. Les feuilles de l'espèce terrestre, B. antiacantha, et de l'espèce épiphyte, W. gigantea, montrent également des similarités de structures comme l'absence de fibres extra-vasculaires et un parenchyme moins développé. La similitude des caractères chez des espèces provenant de différents habitats peut refléter soit les conditions microclimatiques sous lesquelles ces espèces se développent, ou encore des caractéristiques génétiques fixées

The post-transcriptional gene silencing pathway in Eucalyptus

Post-transcriptional gene silencing (PTGS) is a conserved surveillance mechanism that identifies and cleaves double-stranded RNA molecules and their cellular cognate transcripts. The RNA silencing response is actually used as a powerful technique (named RNA interference) for potent and specific inhibition of gene expression in several organisms. To identify gene products in Eucalyptus sharing similarities with enzymes involved in the PTGS pathway, we queried the expressed sequence tag database of the Brazilian Eucalyptus Genome Sequence Project Consortium (FORESTs) with the amino acid sequences of known PTGS-related proteins. Among twenty-six prospected genes, our search detected fifteen assembled sequences encoding products presenting high level of similarity (E value < 10-40) to proteins involved in PTGS in plants and other organisms. We conclude that most of the genes known to be involved in the PTGS pathway are represented in the FORESTs database.496500Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

The new world of RNAs

One of the major developments that resulted from the human genome sequencing projects was a better understanding of the role of non-coding RNAs (ncRNAs). NcRNAs are divided into several different categories according to size and function; however, one shared feature is that they are not translated into proteins. In this review, we will discuss relevant aspects of ncRNAs, focusing on two main types: i) microRNAs, which negatively regulate gene expression either by translational repression or target mRNA degradation, and ii) small interfering RNAs (siRNAs), which are involved in the biological process of RNA interference (RNAi). Our knowledge regarding these two types of ncRNAs has increased dramatically over the past decade, and they have a great potential to become therapeutic alternatives for a variety of human conditions.28529