44 resultados para Modular production

em Repositório Científico do Instituto Politécnico de Lisboa - Portugal


Relevância:

20.00% 20.00%

Publicador:

Resumo:

A concretização do Processo de Bolonha a nível das instituições de ensino superior tornou premente a necessidade de processos de gestão académica envolvendo funcionalidades e formatos de dados heterogéneos. Este trabalho tem por objectivo contribuir para abordar esta necessidade no contexto do ISEL, através da implementação de uma plataforma de integração com características modulares ao nível da camada de negócio do portal académico, no sentido de permitir a integração de subsistemas heterogéneos, quer em termos funcionais, quer em termos de formatos de informação. O projecto Sistema Modular de Gestão Académica (SMGA) foi concretizado através de um protótipo de portal académico que assenta numa arquitectura orientada a serviços, onde é utilizado um modelo de comunicação baseado em mensagens no formato Agent Communication Language (ACL). Este protótipo disponibiliza funcionalidades relacionadas com a gestão académica aos seus utilizadores através de uma aplicação Web de Front Office.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Formaldehyde (CH2O), the most simple and reactive of all aldehydes, is colorless, and readily polymerizing gas at normal temperature. The most extensive use is in production of resins and has an important application as a disinfectant and preservative, reason why relevant workplace exposure may also occur in pathology and anatomy laboratories and in mortuaries. A study was carried out in Portugal, in a formaldehyde production resins factory and in 10 pathology and anatomy laboratories. It was applied a risk assessment methodology based on Queensland University proposal that permitted to perform risk assessment for each activity developed in a work station. This methodology was applied in 83 different activities developed in the laboratories and in 18 activities of the factory. Also, Micronucleus Test was performed in lymphocytes from 30 factory workers and 50 laboratories workers.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A crescente procura da bicicleta como meio de transporte alternativo torna relevante a criação e desenvolvimento de infra-estruturas de apoio, tais como ciclovias e parques para bicicletas. Os sistemas tradicionais de parqueamento de bicicletas com recurso a correntes e cadeados não fornecem segurança nem comodidade. No entanto, começam a surgir, em várias cidades do mundo, parque automáticos onde é possível guardar uma bicicleta em segurança, protegendo-a quer das intempéries quer de actos de vandalismo. Este trabalho apresenta uma proposta para um parque automático de armazenamento de bicicletas, com recurso a caixas individualizadas que garantem a sua segurança, e também de outros bens que podem ser guardados junto da mesma, como por exemplo um capacete ou uma mochila. O sistema proposto no âmbito deste trabalho é um complemento às alternativas existentes. As vantagens apresentadas pelo sistema proposto são: a sua construção modular e personalizada; e a possibilidade de instalação num terreno plano, sem recurso a obras de construção civil. O objectivo foi criar um projecto de automação e controlo de um protótipo, com base na proposta apresentada. O projecto de automação e controlo engloba a escolha dos sensores e dos actuadores. Para o dimensionamento dos motores foi necessário recorrer a um cálculo simplificado da estrutura do robô manipulador. Foi feita a escolha dos sensores, actuadores e do controlador com base nos requisitos funcionais. A programação foi desenvolvida numa linguagem normalizada. O modelo desenvolvido poderá servir de base para um projecto multidisciplinar entre vários departamentos do Instituto e dessa cooperação poderá surgir um novo projecto optimizado para produção e de menor custo.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Esta dissertação insere-se num projecto de investigação relacionado com o papel que a madeira apresenta na construção nos tempos de hoje, necessário para obtenção do Mestrado em Engenharia Civil. A madeira apresenta, enquanto material de construção, especificidades únicas: é um material orgânico, ao contrário da pedra, do aço e do betão; é um material combustível, sem que isto implique necessariamente uma baixa resistência ao fogo; é um material tradicional, presente em pavimentos e coberturas de edifícios antigos e é, paradoxalmente, um material novo, adoptado em arrojadas obras de arquitectura contemporânea. Estas características, associadas à necessidade de garantir a sustentabilidade da construção e de conservar e reabilitar o património edificado, tornam essencial o estudo das propriedades mecânicas do material, dos seus processos de degradação química e biológica, dos meios de protecção e do comportamento de elementos estruturais ao fogo. As estruturas em madeira têm tido uma procura crescente no nosso país, revelando-se uma opção interessante, como alternativa a estruturas de aço ou de betão. No entanto, por configurarem ainda soluções estruturais, materiais e processos construtivos pouco comuns entre nós, considera-se que não estão suficientemente divulgados os instrumentos de que podemos e devemos dispor para a garantia da qualidade destas estruturas. É apresentado um estudo de viabilidade económica no âmbito do nosso país, comparando casas em madeira, modulares pré-fabricadas, com casas cuja construção é feita em alvenaria e betão armado, de forma a poder comparar os custos para ambas as soluções construtivas. Para tal, foram realizadas visitas a empresas, fábricas e a obras com o objectivo de entender como funciona o processo de fabrico de uma casa pré-fabricada em madeira.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Aflatoxin B1 (AFB1) has been recognized to cause cancer in the humans liver. Epidemiological and laboratory evidence also point towards the respiratory system as target for carcinogenesis. Exposure occurs mainly through food chain but inhalation represent an additional route of exposure. Agricultural workers have the greatest risk of occupational exposure due to their exposition to airborne aflatoxin through inhalation of dust.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Este trabalho foi desenvolvido no âmbito de um projecto europeu, BIOPRODUCTION, tendo em vista o desenvolvimento de dois tipos de biomaterias funcionais: ésteres de açúcares com ácidos gordos (SFAE) e metacrilatos funcionais. A síntese laboratorial do biosurfactante SFAE foi efectuada utilizando como matérias-primas diferentes sacáridos, nomeadamente sacarose, glucose e melaço de cana-de-açúcar (mistura de polissacáridos), e ésteres metílicos de ácidos gordos (FAME) de óleos vegetais, tais como colza e coco. Esta síntese é constituída por dois passos: acilação dos açúcares com anidrido acético, e transesterificação do açúcar acilado com FAME, utilizando triflatos de lantanídeos como catalisador. Diferentes estequiometrias foram testadas, bem como diferentes processos de modo a evitar a degradação dos açúcares. Foram efectuados testes preliminares de emulsão e calculou-se, empiricamente, o respectivo HLB. Procedeu-se à caracterização do produto através de FTIR e RMN e também à optimização iterativa do processo de síntese. A modificação, à escala laboratorial, de metacrilatos de metilo (MMA) realizou-se recorrendo à sua transesterificação com polióis convencionais. Efectuaram-se testes de reticulação do produto com diferentes catalisadores e iniciadores para posterior aplicação em revestimentos de borracha. Por fim, para ambos os produtos serão necessários estudos adicionais de caracterização, nomeadamente tensão superficial para os biosurfactantes e propriedades mecânicas para polímeros modificados com MMA.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A descriptive study was developed in order to assess air contamination caused by fungi and particles in seven poultry units. Twenty seven air samples of 25 litters were collected through impaction method. Air sampling and particle concentration measurement were performed in the pavilions’ interior and also outside premises, since this was the place regarded as reference. Simultaneously, temperature and relative humidity were also registered. Regarding fungal load in the air from the seven poultry farms, the highest value obtained was 24040 CFU/m3 and the lowest was 320 CFU/m3. Twenty eight species/genera of fungi were identified, being Scopulariopsis brevicaulis (39.0%) the most commonly isolated species and Rhizopus sp. (30.0%) the most commonly isolated genus. From the Aspergillus genus, Aspergillus flavus (74.5%) was the most frequently detected species. There was a significant correlation (r=0.487; p=0.014) between temperature and the level of fungal contamination (CFU/m3). Considering contamination caused by particles, in this study, particles with larger dimensions (PM5.0 and PM10) have higher concentrations. There was also a significant correlation between relative humidity and concentration of smaller particles namely, PM0.5 (r=0.438; p=0.025) and PM1.0 (r=0.537; p=0.005). Characterizing typical exposure levels to these contaminants in this specific occupational setting is required to allow a more detailed risk assessment analysis and to set exposure limits to protect workers’ health.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper proposes the use of a Modular Marx Multilevel Converter, as a solution for energy integration between an offshore Wind Farm and the power grid network. The Marx modular multilevel converter is based on the Marx generator, and solves two typical problems in this type of multilevel topologies: modularity and dc capacitor voltage balancing. This paper details the strategy for dc capacitor voltage equalization. The dynamic models of the converter and power grid are presented in order to design the converter ac output voltages and the dc capacitor voltage controller. The average current control is presented and used for power flow control, harmonics and reactive power compensation. Simulation results are presented in order to show the effectiveness of the proposed (MC)-C-3 topology.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Aflatoxin B1 (AFB1) has been recognized to produce cancer in human liver. In addition, epidemiological and laboratory studies demonstrated that the respiratory system was a target for AFB1. Exposure occurs predominantly through the food chain, but inhalation represents an additional route of exposure. The present study aimed to examine AFB1 exposure among poultry workers in Portugal. Blood samples were collected from a total of 31 poultry workers from six poultry farms. In addition, a control group (n = 30) was included comprised of workers who undertook administrative tasks. Measurement of AFB1 in serum was performed by enzyme-linked immunosorbent assay (ELISA). For examining fungi contamination, air samples were collected through an impaction method. Air sampling was obtained in pavilion interior and outside the premises, since this was the place regarded as the reference location. Using molecular methods, toxicogenic strains (aflatoxin-producing) were investigated within the group of species belonging to Aspergillus flavus complex. Eighteen poultry workers (59%) had detectable levels of AFB1 with values ranging from <1 ng/ml to4.23 ng/ml and with a mean value of 2 ± 0.98ng/ml. AFB1 was not detected in the serum sampled from any of the controls. Aspergillus flavus was the fungal species third most frequently found in the indoor air samples analyzed (7.2%) and was the most frequently isolated species in air samples containing only Aspergillus genus (74.5%). The presence of aflatoxigenic strains was only confirmed in outdoor air samples from one of the units, indicating the presence of a source inside the building in at least one case. Data indicate that AFB1 inhalation represents an additional risk in this occupational setting that needs to be recognized, assessed, and prevented.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Although a great body of literature exists concerning the ingestion of food contaminated with aflatoxin, there are still few studies regarding mycotoxin inhalation in occupational settings. Since mycotoxins are relatively non-volatile, inhalation exposure is cause by inhalation of airborne fungal particulates or fungi-contaminated substrates that contain aflatoxin. We intend to know if there is occupational exposure to aflatoxin in Portuguese poultry and swine production. A total of 19 individuals (11 swine; 8 poultry) agreed and provided blood samples during the course of this investigation. Measurement of AFB1 was performed by ELISA. The samples were treated with pronase (Merck), wash in a Column C18 and purification was made with immunoaffinity columns (R.biopharma), specific for AFB1. It was applied statistical test (Mann-Whitney) to verified statistical difference in AFB1 results between the two settings. Results varied with concentrations from

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A new Modular Marx Multilevel Converter, M(3)C, is presented. The M(3)C topology was developed based on the Marx Generator concept and can contribute to technological innovation for sustainability by enabling wind energy off-shore modular multilevel power switching converters with an arbitrary number of levels. This paper solves both the DC capacitor voltage balancing problem and modularity problems of multilevel converters, using a modified cell of a solid-state Marx modulator, previously developed by authors for high voltage pulsed power applications. The paper details the structure and operation of the M(3)C modules, and their assembling to obtain multilevel converters. Sliding mode control is applied to a M(3)C leg and the vector leading to automatic capacitor voltage equalization is chosen. Simulation results are presented to show the effectiveness of the proposed M(3)C topology.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The conjugation of antigens with ligands of pattern recognition receptors (PRR) is emerging as a promising strategy for the modulation of specific immunity. Here, we describe a new Escherichia coli system for the cloning and expression of heterologous antigens in fusion with the OprI lipoprotein, a TLR ligand from the Pseudomonas aeruginosa outer membrane (OM). Analysis of the OprI expressed by this system reveals a triacylated lipid moiety mainly composed by palmitic acid residues. By offering a tight regulation of expression and allowing for antigen purification by metal affinity chromatography, the new system circumvents the major drawbacks of former versions. In addition, the anchoring of OprI to the OM of the host cell is further explored for the production of novel recombinant bacterial cell wall-derived formulations (OM fragments and OM vesicles) with distinct potential for PRR activation. As an example, the African swine fever virus ORF A104R was cloned and the recombinant antigen was obtained in the three formulations. Overall, our results validate a new system suitable for the production of immunogenic formulations that can be used for the development of experimental vaccines and for studies on the modulation of acquired immunity.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper, reports experimental work on the use of new heterogeneous solid basic catalysts for biodiesel production: double oxides of Mg and Al, produced by calcination, at high temperature, of MgAl lamellar structures, the hydrotalcites (HT). The most suitable catalyst system studied are hydrotalcite Mg:Al 2:1 calcinated at 507 degrees C and 700 degrees C, leading to higher values of FAME also in the second reaction stage. One of the prepared catalysts resulted in 97.1% Fatty acids methyl esters (FAME) in the 1st reaction step, 92.2% FAME in the 2nd reaction step and 34% FAME in the 3rd reaction step. The biodiesel obtained in the transesterification reaction showed composition and quality parameters within the limits specified by the European Standard EN 14214. 2.5% wt catalyst/oil and a molar ratio methanol:oil of 9:1 or 12:1 at 60 -65 degrees C and 4 h of reaction time are the best operating conditions achieved in this study. This study showed the potential of Mg/Al hydrotalcites as heterogeneous catalysts for biodiesel production. (C) 2011 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Several studies have shown that human exposures to airbome dust and microorganisms, such as bacteria and fungi, can cause respiratory diseases. Agricultural workers have been found to be at high risk of exposures to airborne particles. From a human health perspective dust exposure in pig farming is the most important risk because of the large number of workers needed in pig production and the increasing number of working hours inside enclosed buildings. In the pig buildings, particulate matters like dust play a role in not only deteriorating indoor air quality but also can cause an adverse health effect on workers. Generally, dust is recognized to adsorb and transport odorous compounds and biological agents. The aim of this study was to determine particles contamination in 7 swine farms located in Lisbon district, Portugal.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Agricultural workers especially poultry farmers, are at increased risk of occupational respiratory diseases. In poultry production besides fungi microbial volatile organic compounds (MVOCs) are also present due to compounds released during fungal metabolism. Dust is also one of the risk factors present in animal housing and is comprised by poultry residues, fungi and feathers. A study was developed aiming to assess occupational exposure to fungi, MVOCs and dust in seven poultry units located in Portugal.