Lean production in the precast concrete components’ industry

Proceedings IGLC-19, July 2011, Lima, PerúThis article is a case study applying Lean Thinking and Lean Production principles in a factory that produces prefabricated reinforced concrete components. The objective is to reduce waste production and increase productivity. Nine factories were analyzed, of which one was chosen for developing an implementation model. A number of changes were proposed based on Lean concepts and the study of several similar factories to improve productivity. A Black Belt Team was created to improve the execution and continuance of the lean concepts. Value Stream Mapping was also used as an aid in the identification of existing waste and improvement opportunities, to which various Lean tools were applied in order to solve the identified problems. The main conclusions of this study are that it is possible to achieve a significant improvement in the production system of prefabricated reinforced concrete components using Lean philosophy. Improvements in the reduction of lead-time, reduction of waste and increase in productivity are achieved with simple and low cost technique

Produção Lean na indústria de pré-fabricados de betão armado: aplicação e avaliação de resultados em caso de estudo

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Civil, Perfil de ConstruçãoLean é uma filosofia de produção nascida após a segunda guerra mundial no sector automóvel com intuito de optimizar o sistema de produção. O conceito desta filosofia baseia-se na eliminação de desperdício. Actualmente é aplicada em diversas áreas obtendo-se resultados positivos, tais como: redução de custos, aumento da qualidade, redução de tempo de processamento e aumento de produtividade. Esta dissertação aborda e aplica os princípios fundamentais de Lean Thinking e Lean Production, numa fábrica de elementos pré-fabricados de betão armado. Os objectivos são de reduzir os desperdícios da produção e aumentar a produtividade. Foram analisadas nove fábricas, das quais foi escolhida uma para elaborar um modelo de implementação com diversas propostas de alterações com base nos conceitos Lean e no estudo das diversas fábricas para melhorar produtividade. Neste modelo foi desenvolvido um Black Belt Team, para uma boa implementação e manutenção dos conceitos Lean. Foi também utilizado o Mapeamento do Fluxo de Valor, como auxílio na identificação dos desperdícios existentes e oportunidades de melhoria, ao qual depois foram aplicadas diversas ferramentas e metodologias Lean para solucionar os problemas identificados. As principais conclusões deste estudo são que é possível uma melhoria significativa no sistema de produção de elementos pré-fabricados em betão armado aplicando a filosofia Lean. Melhorias na redução do tempo de produção, na redução dos desperdícios e no aumento da produtividade com técnicas de implementação simples e de baixo custo de intervenção

Modification of butterfat by selective hydrolysis and interesterification by lipase: Process and product characterization

Butterfat was chemically modified via combined hydrolysis and interesterification, catalyzed by a commercial lipase immobilized onto a bundle of hydrophobic hollow fibers. The main goal of this research effort was to engineer butterfat with improved nutritional properties by taking advantage of the sn-1,3 specificity and fatty acid specificity of a lipase in hydrolysis and ester interchange reactions, and concomitantly decrease its level of long-chain saturated fatty acid residues (viz., lauric, myristic, and palmitic acids) and change its melting properties. All reactions were carried out at 40°C in a solvent free system under controlled water activity, and their extent was monitored via chromatographic assays for free fatty acids, esterified fatty acid moieties, and triacylglycerols; the thermal behavior of the modified butterfat was also assessed via calorimetry. Lipase-modified butterfat possesses a wider melting temperature range than regular butterfat. The total saturated triacylglycerols decreased by 2.2%, whereas triacylglycerols with 28–46 acyl carbons (which contained two or three lauric, myristic, or palmitic acid moieties) decreased by 13%. The total monoene triacylglycerols increased by 5.4%, whereas polyene triacylglycerols decreased by 2.9%. The triacylglycerols of interesterified butterfat had ca. 10.9% less lauric, 10.7% less myristic, and 13.6% less palmitic acid residues than those of the original butterfat

From organic chemistry to fat and oil chemistry

With his work on animal fat and identification of fatty acids, Chevreul was a pioneer in organic chemistry. As Chevreul, I had a passion for organic chemistry too. It was then, an honour and a pleasure to present in 2008 at EFL in Athens this presentation entitled “From organic chemistry to fat and oil chemistry” because my background in organic chemistry helped me all along my professional career to understand and implement new developments related to oil and fat technology and processing. Among the topics which I worked out, I highlighted more particularly the following subjects: the degumming chemistry of oil and fat; the improvement of physical refining; a new chemical analytical tool for the dry fractionation; new development in the dry fractionatio

From potential to realized: combining hydrodynamical modelling and habitat quality mapping to study coral connectivity in the Great Barrier Reef

Over the past few years, our team has been committed to simulate connectivity between the >3000 reefs composing the Great Barrier Reef (GBR). This is achieved thanks to SLIM, a high- resolution unstructured-mesh hydrodynamic model. The simulated water currents are used with a Lagrangian particle tracker to simulate the connectivity between all the reefs composing the GBR. This method has been used for a few years now, but is based on fairly strong assumptions. More particularly, until now we considered that every reef is acting the same way when it comes to larval release and likelihood of settlement. The connectivity resulting from this sequence is thus only a potential connectivity. In order to address this simplification, this study is a first attempt to combine previous SLIM results with a new habitat quality index that includes water temperature, cyclones exposure, Crown-of-Thorns starfish outbreaks and land-based pollutants. The relative weight of those four components is estimated from coral cover measures at different years. By doing so, we obtain a global habitat quality index for each reef of the GBR. Potential connectivity provided by the Lagrangian particle tracker is finally weighted by the habitat quality index to compute a more realistic connectivity network that better describes realized connectivity

Monitoring milk fat fractionation: Effect of agitation, temperature, and residence time on physical properties

With the use of two central composite designs, the effects of agitation rate, fractionation temperature, and residence time on the thermal properties of the stearin and olein milk fat fractions were investigated. The main function of agitation during fat fractionation was suspending the crystal aggregates and enhancing the heat transfer. For the experimental conditions described here, crystal aggregation did not seem to be affected by agitation. The effect of fractionation temperature on the physical properties of the olein fraction was very significant, Triangle diagrams were shown to be a useful tool for monitoring and designing fractionation processes. They illustrate that oleins with similar melting properties can be produced over a range of yields of stearin, which is important from an industrial point of view. Crystallizer residence time, which influences production costs, clearly affects both stearin yield and olein melting properties. For any fractionation temperature, stearin fractions with virtually identical melting properties and yields can be obtained over a range of olein melting properties. Manipulation of both the fractionation temperature and residence time allows the fractionation process to be adapted to meet changing market demands for fractions with different melting properties