Controlo de vibrações em pontes pedonais sujeitas a acções de multidões

Dissertação para obtenção do Grau de Mestre em Engenharia Civil - Perfil de EstruturasAs estruturas de Engenharia Civil, quando expostas a acções dinâmicas, podem ser sujeitas a vibrações que comprometem os níveis de segurança e conforto entre os seus utilizadores. Neste trabalho, é estudada a passagem pedonal que faz a ligação entre as Olaias e Chelas, em Lisboa. É desenvolvido um estudo das forças verticais e laterais que os peões induzem na estrutura, por meio de um modelo determinístico proposto pela Sétra-Guidelines. Foi realizada uma análise das vibrações decorrentes na ponte pedonal, verificando-se que os limites em termos de acelerações eram excedidos. De maneira a controlar os problemas de vibrações excessivas, são propostas duas soluções, nomeadamente um sistema de controlo passivo, utilizando amortecedores de massa sintonizada por forma a controlar as vibrações nas direcções vertical e lateral e um sistema de controlo activo, com o objectivo de gerar uma força de controlo adicionada a um TMD, de maneira a reduzir as vibrações decorrentes na direcção lateral. O dimensionamento do sistema de controlo activo foi desenvolvido através do método de alocação de pólos, permitindo alterar directamente as características dinâmicas da estrutura. Por forma a estimar a resposta da estrutura quando dotada de um sistema de controlo activo, foi desenvolvido um programa em MATLAB e SIMULINK. Por fim, foi analisada a resposta da estrutura com um sistema de controlo passivo, através do programa de elementos finitos Sap2000, evidenciando a eficiência das duas técnicas de controlo utilizadas. Desta forma, foi possível reduzir significativamente a resposta da estrutura quando sujeita a acções de multidões, verificando os limites impostos

Response surface methodology in the optimization of extraction conditions for Gracilaria gracilis extracts for use in thermoplastic food coatings

Incorporation of antioxidant agents in edible films and packages often relies in the usage of essential oils and other concentrated hydrophobic liquids, with reliable increases in antimicrobial and antioxidant activities of the overall composite, and consequent improvements in product shelf life. These oils are often obtained from plant sources and the usage of organic solvents in their extraction has been criticized as to whether it constitutes a health hazard for consumers [1, 2, 3]. The use of water-soluble antioxidant agents is less common, due to lower activities and extraction yields. As such, using commonly available seaweeds as the source for both the main polymers and the supplementing antioxidant/antimicrobial agents in bioactive films can potentially reduce production costs and create a safer, more sustainable product [1]. Hydroethanolic extracts of commercially available red macroalgae Gracilaria gracilis were evaluated for their antioxidant potential and phenolic content, as part of the preliminary assays for the selection of algal biomass for the enrichment of thermoplastic films. The extracts were obtained through use of solid-liquid extractions, over which yield, DPPH radical reduction capacity, total phenolic content, and FRAP activity assays were measured [4, 5]. Solid to liquid ratio (SLR), extraction time, and ethanol to water ratio were selected as independent variables with experimental ranges and configurations obtained using a Box-Behnken design with three factors, resulting in 15 experimental conditions. Extraction duplicates were used [4]. Response surface methodology was then used to estimate the effect of each extraction condition on the tested bioactivities. Bioactivities were significantly (p<0.05) and positively affected by the presence of ethanol in the extraction solvent, while extraction yield was reduced. Lower solid to liquid ratios (higher solvent proportions) resulted in higher yields, but had no significant (p<0.05) impact on bioactivities. Time was not a relevant factor in any of the measured variables, and as such will be minimized in any further work. 100% ethanol with minimum extraction time (10 minutes) and 1g to 5mL SLR maximize antioxidant activities per gram of dry extract. Maximum ethanolic yields were obtained with a theoretical extraction of 100 minutes and a 1g to 25mL SLR. Aqueous extractions displayed similar results in terms of optimum conditions, but with overall lower bioactivities and higher yields, very likely due to high amounts of soluble polysaccharides. While the high antioxidant activities from the ethanolic extracts encourage the selection of this solvent for extraction of bioactives, low yields may make them later unfeasible. Future studies over the compatibility of these extracts in the polymeric matrix of the films, as well as further optimization of the extraction process will be necessary before the definitive choice for bioactive origin and processing is made.info:eu-repo/semantics/publishedVersio

Space-temporal evaluation of changes in temperature and soil use and cover in the metropolitan region of baixada santista

The Metropolitan Region of Baixada Santista (MRBS) harbors one of the main port areas of Brazil: the Port of Santos. Due to the accelerated urban development in this region, the monitoring of biophysical parameters is fundamental. Therefore, this paper aims to i) estimate the soil surface temperature (Ts) and identify the Urban Heat Islands (UHI) formation; and ii) compare the Ts and the normalized difference vegetation index (NDVI) for MRBS from 1986 to 2016 using Landsat 5 and 8 images. Remote sensing tools are essential to meet the objectives of this work for providing both the spatial and temporal evaluation of a region. The spatial analysis was based on the NDVI to evaluate the vegetation density and size from five previously established classes (i.e., water bodies, urban grid, exposed soil and road corridors, shrub, and dense vegetation). The NDVI mapping showed a significant reduction in the cover area referred to the dense vegetation class (91.7%), while the urban grid category increased by 29.4%, resulting from the urban expansion and green cover reduction over the region during this period. Surface temperature thematic maps showed high-temperature values related to increased urbanization and decreased rainfall. Moreover, an 8°C rise in surface temperature over the last 30 years was registered due to the regional development, which has replaced natural soils by anthropic materials and reduced dense vegetation. This phenomenon has resulted in the formation and intensification of UHI, especially after the 2000s

Recomendações sobre precauções específicas para acompanhantes/visitantes de pacientes hospitalizados: características e barreiras para implementação

Justificativa e Objetivos: apesar da importância dos acompanhantes/visitantes para pacientes hospitalizados em precauções específicas, nota-se que os riscos de exposição e disseminação de microrganismos nos serviços de saúde por essa população ainda são incipientes na literatura. Dessa forma, objetivou-se caracterizar as recomendações vigentes sobre precauções específicas para acompanhantes e visitantes de pacientes hospitalizados e analisar as barreiras para a sua implementação sob a ótica de prevencionistas de infecção. Métodos: estudo descritivo e exploratório, de abordagem quantitativa, com 89 prevencionistas de infecção, entre março e junho de 2020. Dados coletados por questionário eletrônico, com amostragem tipo “bola de neve” e analisados segundo frequência das respostas. Resultados: a higienização das mãos foi a recomendação mais indicada (>95,0%). Quanto às não conformidades, destacou-se permanecer no quarto sem paramentação (78,6%), frequentar outros quartos (53,9%) e manter portas abertas em precaução para aerossóis (51,7%). Referente às estratégias adotadas para a orientar os acompanhantes/visitantes, houve predomínio da orientação verbal individual (92,4%). A principal barreira citada foi a falta de política institucional (56,2%). Conclusão: não houve uniformidade nas recomendações, e não conformidades e barreiras foram elencadas. Destaca-se a importância de diretrizes de prevenção específicas para esse público e estratégias educativas efetivas para sua implementação

Process Optimization on Rear Bumper Assembly in a PIM Two Wheels Poly Company

The article discusses the relevance of a proper implementation for the rear shock absorber assembly line of motorcycles in a company of Manaus Industrial Pole - PIM, considering the quality techniques and tools used in optimizations. The overall goal is to improve component distribution and rear shock mounting costs for efficiency and effectiveness in the process flow. Specific objectives are to: Avoid wasting time in the process, improve production with optimization techniques, and develop team capacity. In the problem, he observed jobs 6 and 7 with poor “distribution” of components, generating excessive spending. The question arises: How can component “redistribution” optimize and reduce costs for the business? The methodology used was exploratory research, with systematized studies through academic websites, books, bibliographic research and field research with the company with collected data. The optimization procedures were performed with the following tools: Brainstorming, Ishikawa Diagram, 5W2H and Kaizen. Therefore, this paper aims to develop knowledge about the improvements implemented in the assembly line, encouraging the application of quality tools, making it a very efficient option for the organization