From local to global importance measures of uncertainty propagation in composite structures

The influence of uncertainties of input parameters on output response of composite structures is investigated in this paper. In particular, the effects of deviations in mechanical properties, ply angles, ply thickness and on applied loads are studied. The uncertainty propagation and the importance measure of input parameters are analysed using three different approaches: a first-order local method, a Global Sensitivity Analysis (GSA) supported by a variance-based method and an extension of local variance to estimate the global variance over the domain of inputs. Sample results are shown for a shell composite laminated structure built with different composite systems including multi-materials. The importance measures of input parameters on structural response based on numerical results are established and discussed as a function of the anisotropy of composite materials. Needs for global variance methods are discussed by comparing the results obtained from different proposed methodologies. The objective of this paper is to contribute for the use of GSA techniques together with low expensive local importance measures.

Combining global tabu search with local search for solving systems of equalities and inequalities

This papers aims at providing a combined strategy for solving systems of equalities and inequalities. The combined strategy uses two types of steps: a global search step and a local search step. The global step relies on a tabu search heuristic and the local step uses a deterministic search known as Hooke and Jeeves. The choice of step, at each iteration, is based on the level of reduction of the l2-norm of the error function observed in the equivalent system of equations, compared with the previous iteration.

Descentralização e Autonomia Local

A Administração Pública, em sentido orgânico ou subjectivo, pode ser definida como o conjunto de órgãos, serviços e agentes do Estados e demais pessoas colectivas públicas e seus funcionários, que asseguram, em nome da colectividade, a satisfação regular e contínua das necessidades colectivas de segurança, cultura, bem estar e progresso.

Solving MPCC problem with the hyperbolic penalty function

The main goal of this work is to solve mathematical program with complementarity constraints (MPCC) using nonlinear programming techniques (NLP). An hyperbolic penalty function is used to solve MPCC problems by including the complementarity constraints in the penalty term. This penalty function [1] is twice continuously differentiable and combines features of both exterior and interior penalty methods. A set of AMPL problems from MacMPEC [2] are tested and a comparative study is performed.

Solving a signalized traffic intersection problem with an hyperbolic penalty function

Mathematical Program with Complementarity Constraints (MPCC) finds many applications in fields such as engineering design, economic equilibrium and mathematical programming theory itself. A queueing system model resulting from a single signalized intersection regulated by pre-timed control in traffic network is considered. The model is formulated as an MPCC problem. A MATLAB implementation based on an hyperbolic penalty function is used to solve this practical problem, computing the total average waiting time of the vehicles in all queues and the green split allocation. The problem was codified in AMPL.

When Corporate Governance crosses the firm borders: family firms in local productive systems

The family involvement in firms is observable is most economies around the world, although there are significant differences among these countries, not only regarding its predominance in these economies, but also in what refers to the levels of involvement of the family in business. This research aims at understanding the family-based firms’ management when compared to non family based, with particular regards to the forms of corporate governance. This analysis is based on case studies and on secondary data found in the literature to support the findings from the empirical research. The data was collected via face to face in-depth interviews with entrepreneurs from the furniture and the events organisation industries (where the family is predominantly present in the furniture but not on the events organisation industry) and with industry and regional business associations. The case studies used in this research allowed the comparison between the Portuguese firms when the family plays an important role in business and those in which the family is absent. It has been found that there are important differences in businesses in countries/industries/local productive systems in which the family is seen as a dominant institution in the society (where businesses are based on strong ties; there is a harmonious relationship between the family members; and the family is accepted locally and dominates the firm organization) and on situations in which the family plays a more marginal role in the society. In fact, the family brings special characteristics to the business, in terms of management, corporate governance, inter and intra firm relationships and succession. Our findings confirm other empirical studies’ results found in the literature. Thus, this article provides a discussion on the factors that play a role in the form of corporate governance structure in family firms highlighting the pros and cons of organising the firm around the family.

Os modelos de governance nas nonprofit organizations de actuação local: uma revisão de literatura

O crescimento do sector não lucrativo, por força da criação de novas organizações sem fins lucrativos, tem-se acentuado nos últimos anos tentando dar resposta ao serviço público que a comunidade exige e que o Estado não tem sabido dar resposta. O sector não lucrativo, ou terceiro sector, realiza funções sociais ou culturais relevantes para a sociedade sem o objectivo de produzir lucros. Em Portugal não existem, para este sector, padrões específicos para os modelos de gestão nem tipologias de informação a utilizar pelos seus stakeholders e, por isso, utilizam-se os mesmos moldes do sector empresarial, cumprindo assim a real consistência do isomorfismo mimético. Existe claramente uma diferença entre os objectivos da informação financeira e não financeira nas organizações lucrativas e nas não lucrativas, e essa destrinça tem a ver directamente com os tipos de destinatários e utilizadores da informação. A abordagem às práticas de corporate governance é uma incontornável realidade no mundo organizacional actual face ao crescente aumento das preocupações das organizações enquanto agentes económicos, sociais e políticos. A sociedade exige às organizações não lucrativas transparência e accountability da informação financeira e não financeira (Carvalho & Blanco, 2007a)) e por isso a adopção de práticas de governance pode trazer benefícios na solução de alguns problemas de gestão. Esta investigação pretende, assim, fazer uma revisão de literatura sobre os modelos de governance, numa abordagem à gestão das organizações sem fins lucrativos de âmbito local, contribuindo assim para a possível definição de um modelo de governance próprio para o sector não lucrativo português.

On local fractional continuous wavelet transform

We introduce a new wavelet transform within the framework of the local fractional calculus. An illustrative example of local fractional wavelet transform is also presented.

Bullying no local de trabalho: a perceção dos profissionais de uma Instituição de Ensino Superior Politécnico norte do país

Dissertação apresentada ao Instituto Politécnico do Porto para obtenção do Grau de Mestre em Gestão das Organizações, Ramo de Gestão de Empresas. Orientada por Prof. Doutor Manuel Salvador Gomes de Araújo

Métodos construtivos de pontes

Para a construção de uma estrutura há diversos factores que influenciam a sua concepção, tais como o vão, a topografia do local, acessibilidades, os possíveis acidentes do terreno, como cursos de água ou a sua função. É de ressalvar ainda que o enquadramento paisagístico cada vez mais é tido em conta, embora não seja determinante para a sua função ou dimensionamento. Na construção de pontes existe uma grande variedade de métodos construtivos a usar variando estes com a dimensão da obra ou com a disponibilidade de equipamento por parte do empreiteiro. Cada vez mais deverá ser bem analisado o sistema a usar, uma vez que o custo do processo construtivo constitui uma percentagem elevada do valor final da obra, podendo ser reduzidos os custos pela escolha acertada do método. Com a presente dissertação pretende-se analisar os diferentes métodos construtivos existentes no mercado, sendo estes distinguidos entre sistemas com aplicação de préfabricação ou com betonagem in-situ, e ainda o processo a usar em função do vão a vencer.

Detection of ZnS phases in CZTS thin-films by EXAFS

Copper zinc tin sulfide (CZTS) is a promising Earthabundant thin-film solar cell material; it has an appropriate band gap of ~1.45 eV and a high absorption coefficient. The most efficient CZTS cells tend to be slightly Zn-rich and Cu-poor. However, growing Zn-rich CZTS films can sometimes result in phase decomposition of CZTS into ZnS and Cu2SnS3, which is generally deleterious to solar cell performance. Cubic ZnS is difficult to detect by XRD, due to a similar diffraction pattern. We hypothesize that synchrotron-based extended X-ray absorption fine structure (EXAFS), which is sensitive to local chemical environment, may be able to determine the quantity of ZnS phase in CZTS films by detecting differences in the second-nearest neighbor shell of the Zn atoms. Films of varying stoichiometries, from Zn-rich to Cu-rich (Zn-poor) were examined using the EXAFS technique. Differences in the spectra as a function of Cu/Zn ratio are detected. Linear combination analysis suggests increasing ZnS signal as the CZTS films become more Zn-rich. We demonstrate that the sensitive technique of EXAFS could be used to quantify the amount of ZnS present and provide a guide to crystal growth of highly phase pure films.

Local fractional variational iteration and decomposition methods for wave equation on cantor sets within local fractional operators

We perform a comparison between the fractional iteration and decomposition methods applied to the wave equation on Cantor set. The operators are taken in the local sense. The results illustrate the significant features of the two methods which are both very effective and straightforward for solving the differential equations with local fractional derivative.