Analysis of sandwich beam structures using kriging based higher order models

Functionally graded composite materials can provide continuously varying properties, which distribution can vary according to a specific location within the composite. More frequently, functionally graded materials consider a through thickness variation law, which can be more or less smoother, possessing however an important characteristic which is the continuous properties variation profiles, which eliminate the abrupt stresses discontinuities found on laminated composites. This study aims to analyze the transient dynamic behavior of sandwich structures, having a metallic core and functionally graded outer layers. To this purpose, the properties of the particulate composite metal-ceramic outer layers, are estimated using Mod-Tanaka scheme and the dynamic analyses considers first order and higher order shear deformation theories implemented though kriging finite element method. The transient dynamic response of these structures is carried out through Bossak-Newmark method. The illustrative cases presented in this work, consider the influence of the shape functions interpolation domain, the properties through-thickness distribution, the influence of considering different materials, aspect ratios and boundary conditions. (C) 2014 Elsevier Ltd. All rights reserved

Optimal design of piezolaminated structures using B-spline strip finite element models

A package of B-spline finite strip models is developed for the linear analysis of piezolaminated plates and shells. This package is associated to a global optimization technique in order to enhance the performance of these types of structures, subjected to various types of objective functions and/or constraints, with discrete and continuous design variables. The models considered are based on a higher-order displacement field and one can apply them to the static, free vibration and buckling analyses of laminated adaptive structures with arbitrary lay-ups, loading and boundary conditions. Genetic algorithms, with either binary or floating point encoding of design variables, were considered to find optimal locations of piezoelectric actuators as well as to determine the best voltages applied to them in order to obtain a desired structure shape. These models provide an overall economy of computing effort for static and vibration problems

Tratamento de efluentes da indústria de conservas de peixe por coagulação-floculação com diferentes coagulantes

Os principais problemas ambientais das indústrias de conservas de peixe são o elevado consumo de água e o elevado conteúdo de matéria orgânica, óleos e gorduras e sais nos seus efluentes. Cada vez mais há uma necessidade de se considerar o tratamento deste tipo de efluentes de forma a que estes cumpram os requisitos de qualidade ditados pela legislação. Assim, este trabalho tem como objectivo o estudo do tratamento primário de efluentes da indústria de conservas de peixe através de um tratamento por coagulação-floculação química. Para tal, testaram-se quatro coagulantes diferentes (um orgânico e três inorgânicos) e várias concentrações de cada um deles (100, 200 e 400 mg/L), de forma a seleccionar as melhores condições do processo. Contudo, observou-se que não existe um único coagulante óptimo, tudo depende do objectivo pretendido. Entre as condições estudadas pode-se afirmar que, se o objectivo for a maximização da remoção de óleos e gorduras, a melhor opção será a utilização de 200 mg/L de cloreto de polialumínio, atingindo remoções de 99,5%. Se o pretendido for a remoção de sólidos suspensos totais, é recomendada a utilização de 400 mg/L de cloreto de ferro, obtendo remoções de 85,8%.Este trabalho é parcialmente financiado pela FCT –Fundação para a Ciência e a Tecnologia e pelo FEDER sob o programa COMPETE (Projecto PEst-C/EQB/LA0020/2013) e pelo projecto ValorPeixe –Valorização de subprodutos e águas residuais da indústrias de conservas de peixe, projecto em co-promoção I&DT QREN, nº 13634, financiado pelo FEDER através do POFC – Programa Operacional Factores de Competitividade, pelos quais os autores estão agradecidos. Os autores querem também agradecer à indústria de conservas de peixe em estudo pelas amostras de efluente e à Rivaz Química (Maia, Portugal) por cederem gentilmente o coagulante orgânico RIPOL 070. A autora Raquel O. Cristóvão quer também agradecer à FCT pela sua bolsa de pós-doutoramento (SFRH/BPD/81564/2011).info:eu-repo/semantics/publishedVersio

Experiência no curso de estudantes de 1º ano – um estudo no âmbito das tutorias de acompanhamento na Universidade de Évora

O presente estudo pretende conhecer a experiência no curso de estudantes de 1º ano que ingressaram na Universidade de Évora no final do 1º semestre. Estudos realizados sobre a percepção dos estudantes relativa ao contexto de aprendizagem no ensino superior indicam forte relação com as abordagens à aprendizagem e apresentam forte relevância para a compreensão da forma como os estudantes acedem ao conhecimento e para a definição de processos de aprendizagem de elevada qualidade (Entwistle, 2009; Chaleta & Entwistle, 2011). Os dados foram obtidos através da aplicação do CEQP (Ramsden, 2005; 2006; Chaleta et al, 2012) com 565 estudantes de diferentes cursos e áreas científicas. Os resultados indicaram que a experiência no curso é positiva para o conjunto dos estudantes havendo necessidade de observar com mais atenção as questões relacionadas com a avaliação. A grande maioria dos estudantes revela também satisfação com o curso que frequenta. Palavras-Chave: Experiência no Curso; Tutorias de Acompanhamento; CEQP; Ensino Superior. Abstract This study examine the experience in the course of the 1st year students who entered at the University of Évora. Studies on the perception of students on the learning environment in higher education indicate a strong relationship with the approaches to learning and have strong relevance to the understanding how students access the knowledge and the definition of high quality learning processes (Entwistle, 2009; Chaleta & Entwistle, 2011). The data were obtained by applying the CEQP (Ramsden, 2005, 2006; Chaleta et al, 2012) with 565 students from different courses and scientific areas. The results indicated that the course experience is positive for all the students but we need to look more closely at the issues related to assessment. The vast majority of students also reveals satisfaction with the course who attends Keywords: Course Experience; Mentor Monitoring; CEQP; Higher Education

A discrete model for the design sensitivity analysis of multi-layered composite shells of revolution

This paper studies the sensitivity analysis for the optimization of the multi-layered composite axisymmetric shells subjected to arbitrary static loading and free vibrations. The structural analysis is carried out using a two node frustum-cone finite element with 16 degrees of freedom based on Love-Kirchhoff assumptions. The design variables are the angle of orientation of the fibers and/or the vectorial distances from middle surface to upper surface of each ply. The constraint functions are displacements, stresses (Tsai-Hill criterion) and the natural frequency of a specified mode shape. Four types of objective functions can be used: maximum displacement or natural frequency or elastic strain energy and material volume. The design sensitivities are calculated analytically, semi-analytically and by global finite difference. The potentiality of the proposed model and the accuracy of the sensitivities of response are discussed with reference to the applications.info:eu-repo/semantics/publishedVersio

Primary treatment optimization of a fish canning wastewater from a Portuguese plant

A sequence with three stages was optimized as a primary treatment for wastewaters from a fish canning industry of northern Portugal. Sedimentation tests were assessed at different times. The removal of a high fraction (75%) of oil and grease (O&G) and of some (48%) total suspended solids (TSS) occurred after a settling time of 1.5h. Coagulant dosage and pH value were optimized in the coagulation/flocculation treatment using several organic and inorganic coagulants. Best removal efficiencies (99.2% O&G, 85.8% TSS and 25.2% dissolved organic carbon (DOC)) were reached using 400mg/L of FeCl3 at raw pH wastewater. DAF was also tested, optimizing chamber pressure and recycle ratio. Removals of 94% for O&G and 43% for TSS were achieved. The coupling of the latter two processes was also investigated, but no improvement of the previous results was observed. The best approach proved to be a decantation process followed by coagulation/flocculation treatment. © 2014 The Authors

Tratamento de efluentes da indústria de conservas de peixe com vista à sua reutilização

É de grande interesse ambiental e económico estudar o tratamento de efluentes da indústria de conservas de peixe de forma a obter uma água com os requisitos de qualidade necessários para considerar a sua reutilização e/ou reciclagem para a unidade industrial. No entanto, o elevado conteúdo de sal tem sido um fator limitante, pois persiste mesmo após o tratamento convencional dos efluentes. Assim, foi estudado e otimizado um processo de clarificação por filtração rápida, osmose inversa e desinfeção UV, como tratamento de afinação do efluente previamente tratado, de modo a remover sólidos, sais e microrganismos remanescentes. Este tratamento de afinação permitiu alcançar eficiências de remoção de 78% de sólidos suspensos totais, 97,3% de carbono orgânico dissolvido, 99,8% de azoto total solúvel, 99,1% de condutividade, acima de 96% de aniões e catiões e 100% de bactérias heterotróficas (UFC), atingindo-se, como pretendido, água com os requisitos de qualidade necessários para ser reutilizada ou reciclada para a unidade industrial. Consequentemente, é possível uma redução da descarga de efluentes, uma limitação do uso de água e uma redução dos custos associados.Este trabalho é parcialmente suportado pelo projeto PEst C/EQB/LA0020/2013, financiado pela FEDER através do Programa Operacional Fatores de Competitividade –COMPETE e pela Fundação para a Ciência e a Tecnologia –FCT e pelo projeto em co-promoção I&DT QREN nº 13634, ValorPeixe – Valorização de Subprodutos e Águas Residuais da Indústria de Conservas de Peixe, financiado pela FEDER através do Programa Operacional Fatores de Competitividade POFC aos quais os autores se encontram agradecidos. Os autores querem também agradecer à indústria de conservas em estudo pelas amostras de efluente. A autora Raquel O. Cristóvão agradece também à FCT pela bolsa de Pós-doutoramento (SFRH/BPD/81564/2011).info:eu-repo/semantics/publishedVersio

Fish canning industry wastewater treatment for water reuse – a case study

The valorization of wastewaters from the fish canning industry is of great concern, not only because of the high quantities generated, but also economic and environmental benefits may result from a proper treatment approach of the waste generated while reducing costs related to wastewater discharge. A limiting factor for reuse and recycling treated fish canning wastewater into an industrial plant and also for other uses is the high salt content, which persists even after conventional treatment. So, the reuse of fish canning industrial wastewater was assessed by combining conventional treatments, such as sedimentation, chemical coagulation-flocculation and aerobic biological degradation (activated sludge process) followed by a polishing step by reverse osmosis (RO) and ultraviolet (UV) disinfection. In this investigation all these processes were optimized in order to remove essentially the effluent suspended particles (primary treatment), the organic matter content in the biological aerated reactor (secondary treatment) and, finally, the remaining salts and microorganisms (tertiary treatment). The overall removal efficiencies obtained were: 99.9% for dissolved organic carbon (DOC), 99.8% for oil and grease (O&G), 98.4% for total suspended solids (TSS), above 96% for anions and cations and 100% for heterotrophic bacteria expressed as colony-forming units (CFU). The final clarified effluent was found to have the quality requirements to be recycled or reused in the industrial plant, allowing the reduction of the effluent to be discharged, the water use and the costs of tap water for industrial use. As regards the energy and chemicals costs, to obtain a treated effluent to be reused in the process costs 0.85 V/m3. This value can be reduced by about 60% if the goal is only to meet the legislated standards for the effluent discharge into water bodies. Tap water for the industrial plant costs about 2.1 V/m3.This work is partially supported by project PEst-C/EQB/LA0020/2013,financed by FEDER through COMPETE - Programa Operacional Factores de Competitividade and by FCT - Fundação para a Ciência e a Tecnologia and by ValorPeixe - Valorizaçãode Sub-produtos e Águas Residuais da Indústria de Conservas de Peixe, project in co-promotion I&DT QREN, nº13634,financed by FEDER through POFC - Programa Operacional Factores de Competitividade for which the authors are thankful. Raquel O. Cristóvão thanks FCT for the Post-doc Scholarship (SFRH/BPD/81564/2011).info:eu-repo/semantics/publishedVersio

Higher order model for analysis of magneto-electro-elastic plates

In this paper is presented an higher-order model for static and free vibration analyses of magneto-electro-elastic plates, wich allows the analysis of thin and thick plates, which allows the analysis of thin and thick plates. The finite element model is a single layer triangular plate/shell element with 24 degrees of fredom for the generalized mechanical displacements. Two degrees on freedom are introduced per each element layer, one corresponding to the electrical potential and the other for magnetic potential. Solutions are obtained for different laminations of the magneto-electro-elastic plate, as well as for the purely elastic plate as a special case