Study on the glycerolysis reaction of high free fatty acid oils for use as biodiesel feedstock

Biodiesel is the main alternative to fossil diesel and it may be produced from different feedstocks such as semi-refined vegetable oils, waste frying oils or animal fats. However, these feedstocks usually contain significant amounts of free fatty acids (FFA) that make them inadequate for the direct base catalyzed transesterification reaction (where the FFA content should be lower than 4%). The present work describes a possible method for the pre-treatment of oils with a high content of FFA (20 to 50%) by esterification with glycerol. In order to reduce the FFA content, the reaction between these FFA and an esterification agent is carried out before the transesterification reaction. The reaction kinetics was studied in terms of its main factors such astemperature, % of glycerin excess, % of catalyst used, stirring velocity and type of catalyst used. The results showed that glycerolysis is a promising pretreatment to acidic oils or fats (> 20%) as they led to the production of an intermediary material with a low content of FFA that can be used directly in thetransesterification reaction for the production of biodiesel. (C) 2011 Elsevier B.V. All rights reserved.

Criação de valor, gestão de risco e as medidas de performance ajustadas ao risco: aplicação do RAROC - Risk Adjustment Return on Capital - ao grupo crédito agrícola

Mestrado em Contabilidade e Gestão das Instituições Financeiras

Estudo empírico sobre os determinantes da estrutura de capital em Portugal

Dissertação de Mestrado, Ciências Económicas e Empresariais, 13 de Dezembro de 2012, Universidade dos Açores.

Derivative-free optimization and filter methods to solve nonlinear constrained problems

In real optimization problems, usually the analytical expression of the objective function is not known, nor its derivatives, or they are complex. In these cases it becomes essential to use optimization methods where the calculation of the derivatives, or the verification of their existence, is not necessary: the Direct Search Methods or Derivative-free Methods are one solution. When the problem has constraints, penalty functions are often used. Unfortunately the choice of the penalty parameters is, frequently, very difficult, because most strategies for choosing it are heuristics strategies. As an alternative to penalty function appeared the filter methods. A filter algorithm introduces a function that aggregates the constrained violations and constructs a biobjective problem. In this problem the step is accepted if it either reduces the objective function or the constrained violation. This implies that the filter methods are less parameter dependent than a penalty function. In this work, we present a new direct search method, based on simplex methods, for general constrained optimization that combines the features of the simplex method and filter methods. This method does not compute or approximate any derivatives, penalty constants or Lagrange multipliers. The basic idea of simplex filter algorithm is to construct an initial simplex and use the simplex to drive the search. We illustrate the behavior of our algorithm through some examples. The proposed methods were implemented in Java.

Derivative-free nonlinear optimization filter simplex

The filter method is a technique for solving nonlinear programming problems. The filter algorithm has two phases in each iteration. The first one reduces a measure of infeasibility, while in the second the objective function value is reduced. In real optimization problems, usually the objective function is not differentiable or its derivatives are unknown. In these cases it becomes essential to use optimization methods where the calculation of the derivatives or the verification of their existence is not necessary: direct search methods or derivative-free methods are examples of such techniques. In this work we present a new direct search method, based on simplex methods, for general constrained optimization that combines the features of simplex and filter methods. This method neither computes nor approximates derivatives, penalty constants or Lagrange multipliers.

Sraffa on Fixed Capital, Money and the Phases of Capitalism

Copyright © 2014 Taylor & Francis.

Capital social y promoción de la salud en América Latina

América Latina enfrenta problemáticas de desarrollo y salud comunes. La equidad y la superación de la pobreza son cruciales en la búsqueda de soluciones integrales y de alto impacto. El artículo analiza el concepto de capital social, su relación con salud, sus limitaciones y potencialidades, desde una perspectiva de desarrollo comunitario y promoción de salud en América Latina. También, se identifican desafíos prioritarios, como la medición y fortalecimiento del capital social. Se discute cómo y por qué el capital social pudiera ser crítico en una estrategia global de promoción de la salud, donde el empoderamiento y la participación comunitaria, el trabajo interdisciplinario e intersectorial permitirían avanzar en los objetivos de salud pública y en la concreción de un cambio social sustentable. Igualmente, se identifican algunas de las potenciales limitaciones del concepto de capital social en el contexto de promoción de la salud en América Latina.

A questão da língua na União Europeia – implicações sobre a liberdade de circulação de mercadorias

Dissertação apresentada ao Instituto Superior de Contabilidade e Administração do Porto para a obtenção do Grau de Mestre em Empreendedorismo e Internacionalização Orientada pela Mestre Maria Luísa Verdelho Alves

The gambin model provides a superior fit to species abundance distributions with a single free parameter : evidence, implementation and interpretation

The species abundance distribution (SAD) has been a central focus of community ecology for over fifty years, and is currently the subject of widespread renewed interest. The gambin model has recently been proposed as a model that provides a superior fit to commonly preferred SAD models. It has also been argued that the model's single parameter (α) presents a potentially informative ecological diversity metric, because it summarises the shape of the SAD in a single number. Despite this potential, few empirical tests of the model have been undertaken, perhaps because the necessary methods and software for fitting the model have not existed. Here, we derive a maximum likelihood method to fit the model, and use it to undertake a comprehensive comparative analysis of the fit of the gambin model. The functions and computational code to fit the model are incorporated in a newly developed free-to-download R package (gambin). We test the gambin model using a variety of datasets and compare the fit of the gambin model to fits obtained using the Poisson lognormal, logseries and zero-sum multinomial distributions. We found that gambin almost universally provided a better fit to the data and that the fit was consistent for a variety of sample grain sizes. We demonstrate how α can be used to differentiate intelligibly between community structures of Azorean arthropods sampled in different land use types. We conclude that gambin presents a flexible model capable of fitting a wide variety of observed SAD data, while providing a useful index of SAD form in its single fitted parameter. As such, gambin has wide potential applicability in the study of SADs, and ecology more generally.

O equilibrio do capital: panorama científico, histórico, e doutrinal da análise contábil e consultoria superior

O equilíbrio do capital é um estado por excelência estudado pelos diversos cientistas de nossa disciplina, sendo que, por sua alta relevância, chegou a ser considerado objeto de estudos da contabilidade, em doutrina contábil específica. Realmente, o ponto de harmonia entre a proporção e o movimento, das principais partes do patrimônio, é, para que toda a organização constituída possua o estado de fortuna e prosperidade. As pesquisas dos grandes doutrinadores da contabilidade brasileira e estrangeira, formam um arcabouço que nos serve de base para a produção de uma consultoria superior que se realiza por meio da análise patrimonial, cuja finalidade é diagnosticar e orientar conforme o caso, as empresas, na correta manutenção dos seus investimentos, financiamentos, custos, receitas e rédito. O objetivo deste artigo é tratar alguns pontos desta doutrina geral, que expõe os princípios do equilíbrio, noção sublime para a formação de orientações especiais, que visam a sanidade do capital ordenadamente constituído.

Impacto da adopção das IAS/IFRS no capital próprio e no resultado líquido nas empresas portuguesas cotadas

Mestrado em Contabilidade Internacional

O branqueamento de capitais no sector bancário

Mestrado em Contabilidade e Gestão de Instituições Financeiras

A gestão baseada no valor: Métricas tradicionais e medidas de performance ajustada ao risco. Risk Adjusted Return on Capital (RAROC) - Aplicação prática à actividade bancária

Mestrado em Contabilidade e Gestão das Instituições Financeiras

Contabilidade do capital humano: considerações na aplicação de uma PME

Mestrado em Contabilidade