Numerical Simulation of a Suction Valve: Comparison between a 3D Complete Model and a 1D Model

Hermetic reciprocating compressors are widely used in small and medium size vapor compression refrigeration systems. One of the main parts of this type of compressor is the automatic valve system used to control the suction and discharge processes. As the opening and closing of the valves are caused by the forces produced by the refrigerant flow itself, the understanding of this fluid-structure interaction problem which characterizes the system dynamics is of fundamental importance in order to enhance the efficiency of the valve system. The numerical simulation of the flow has been used as an efficient method to perform this task. Most of the researchers simulated this problem by considering whether a geometric simplification for the valve (radial diffuser) or a simplification for the dynamics of the structure (one degree of freedom). In order to overcome these two drawbacks, in this work we simulate numerically the fluid structure interaction problem in a real geometry usually used in suction valves by considering a 3D complete model for both the flow and the dynamics of the structure. The Ansys CFX CFD-Computational Fluid Dynamics software was used for the simulation of the flow coupled with the structure module available in the Ansys Mechanical. In addition, a 1D model (one degree of freedom) was also implemented for simulating the dynamics of the structure for comparison reasons. The models were validated against experimental data for the aperture of the valve. We show that the 1D model saves small computational time and provides good results for general characteristics of the problem as the force acting on the valve and the aperture of the valve, while the 3D complete model allows us to predict the deformation of the structure. We suggest the use of the 3D complete model because the computational time is not significantly increased

Estudando Ciências e Matemática por meio de projetos: lançamento de foguetes

Este trabalho trata de um relato de uma experiência de formação em ensino de Ciências desenvolvido em uma escola pública de ensino médio por alunos de cursos de formação de professores de Matemática, Física e por alunos dos primeiros anos dos cursos de Física e Engenharia Mecânica e Civil. Dentre os objetivos deste projeto está o de desenvolver uma estrutura de trabalho que possibilite que estudantes universitários em formação tenham oportunidades de se envolver em um problema complexo, um problema em um contexto real de uma escola e desenvolver estratégias de resolução de problemas

Desenvolvimento de projetos: um trabalho para a integração universidade/escola técnica

In this article we present a research work developed with the groups of the mechanics students of the High School to explore the projects pedagogical practices. For the technical students too It is necessary to give opportunities for qualifies them to create, to judge and to development any project, since your original idea, until the operation of the products. Thus, we worked the mechanics of the harmonic motions under the softened and forced oscillations conditions, and several technological applications. These problems are precariously explored in the didactic books and laboratories. Like this, we proposed to project and to make a prototype of an oscillator that allows to explorer all the relationship of the variables and the dynamic situations which the subject to can provide for understanding the sciences of the mechanical oscillations. The work was realized by including since its conception on the general plan, and the dimensional shipping of the parts, and drawings in Auto-CAD software, until the operation of the mechanisms. The work still included the making of the mechanical components. The oscillator constructed is a mass-spring system, with backup for the operation. It allows to study, since the simple harmonic motion until the effects of the external forces to the under-critical, the critical and the super-critical attenuation. The results allows to correlate the different variables and respective scientific-technological meanings, associating the physical parameters with the consensual mathematical models. The essence of this proposal was to present the challenge for learning sciences from the technological projects developments.No presente artigo, apresentamos resultados de pesquisa em extensão, desenvolvida com grupos de alunos de Mecânica de uma Escola Técnica Profissionalizante explorando a pedagogia de projetos. Ao técnico também é necessário dar-lhes oportunidades para obter um desenvolvimento profissional que os capacite a criar e a julgar um projeto, desde a sua idealização até a operação de um produto final. Com estes objetivos, propusemos um trabalho com abordagens teórica/experimental da mecânica de movimentos harmônicos. Este tema é precariamente apresentado em livros e em laboratórios didáticos. Assim, propusemos projetar e desenvolver um protótipo de um sistema que permita estudar as inúmeras variáveis e situações dinâmicas que o assunto pode oferecer a partir de registros de dados experimentais. Foram idealizados, dimensionados os componentes e os desenhos feitos em Auto-CAD, incluindo os detalhes técnicos para operação dos mecanismos e confecção dos componentes em oficinas. O sistema construído foi um oscilador mecânico tipo massa-mola, versátil, contando com opções para estudar, desde o MHS, algumas oscilações sob ação de uma força alternada externa, até investigar oscilações com amortecimentos crítico, sub-crítico e supercrítico, tópicos fundamentais em diversas aplicações tecnológicas. Os dados constituídos permitem correlacionar diferentes variáveis e seus respectivos significados científico-tecnológicos, contextualizando os parâmetros físicos envolvidos e associando-os aos modelos matemáticos consensuais, alcançando a essência da proposta e que representaram o grande desafio de aprender ciências a partir do desenvolvimento de projetos tecnológicos com conceitos da física e de engenharia

Desenvolvimento de projetos: um trabalho para a integração universidade/escola técnica

In this article we present a research work developed with the groups of the mechanics students of the High School to explore the projects pedagogical practices. For the technical students too It is necessary to give opportunities for qualifies them to create, to judge and to development any project, since your original idea, until the operation of the products. Thus, we worked the mechanics of the harmonic motions under the softened and forced oscillations conditions, and several technological applications. These problems are precariously explored in the didactic books and laboratories. Like this, we proposed to project and to make a prototype of an oscillator that allows to explorer all the relationship of the variables and the dynamic situations which the subject to can provide for understanding the sciences of the mechanical oscillations. The work was realized by including since its conception on the general plan, and the dimensional shipping of the parts, and drawings in Auto-CAD software, until the operation of the mechanisms. The work still included the making of the mechanical components. The oscillator constructed is a mass-spring system, with backup for the operation. It allows to study, since the simple harmonic motion until the effects of the external forces to the under-critical, the critical and the super-critical attenuation. The results allows to correlate the different variables and respective scientific-technological meanings, associating the physical parameters with the consensual mathematical models. The essence of this proposal was to present the challenge for learning sciences from the technological projects developments.No presente artigo, apresentamos resultados de pesquisa em extensão, desenvolvida com grupos de alunos de Mecânica de uma Escola Técnica Profissionalizante explorando a pedagogia de projetos. Ao técnico também é necessário dar-lhes oportunidades para obter um desenvolvimento profissional que os capacite a criar e a julgar um projeto, desde a sua idealização até a operação de um produto final. Com estes objetivos, propusemos um trabalho com abordagens teórica/experimental da mecânica de movimentos harmônicos. Este tema é precariamente apresentado em livros e em laboratórios didáticos. Assim, propusemos projetar e desenvolver um protótipo de um sistema que permita estudar as inúmeras variáveis e situações dinâmicas que o assunto pode oferecer a partir de registros de dados experimentais. Foram idealizados, dimensionados os componentes e os desenhos feitos em Auto-CAD, incluindo os detalhes técnicos para operação dos mecanismos e confecção dos componentes em oficinas. O sistema construído foi um oscilador mecânico tipo massa-mola, versátil, contando com opções para estudar, desde o MHS, algumas oscilações sob ação de uma força alternada externa, até investigar oscilações com amortecimentos crítico, sub-crítico e supercrítico, tópicos fundamentais em diversas aplicações tecnológicas. Os dados constituídos permitem correlacionar diferentes variáveis e seus respectivos significados científico-tecnológicos, contextualizando os parâmetros físicos envolvidos e associando-os aos modelos matemáticos consensuais, alcançando a essência da proposta e que representaram o grande desafio de aprender ciências a partir do desenvolvimento de projetos tecnológicos com conceitos da física e de engenharia

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time, and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space. While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes, vast areas of the tropics remain understudied. In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity, but it remains among the least known forests in America and is often underrepresented in biodiversity databases. To worsen this situation, human-induced modifications may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge, it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost