Random path sampling applied to vector models of magnetism

The recently reported Monte Carlo Random Path Sampling method (RPS) is here improved and its application is expanded to the study of the 2D and 3D Ising and discrete Heisenberg models. The methodology was implemented to allow use in both CPU-based high-performance computing infrastructures (C/MPI) and GPU-based (CUDA) parallel computation, with significant computational performance gains. Convergence is discussed, both in terms of free energy and magnetization dependence on field/temperature. From the calculated magnetization-energy joint density of states, fast calculations of field and temperature dependent thermodynamic properties are performed, including the effects of anisotropy on coercivity, and the magnetocaloric effect. The emergence of first-order magneto-volume transitions in the compressible Ising model is interpreted using the Landau theory of phase transitions. Using metallic Gadolinium as a real-world example, the possibility of using RPS as a tool for computational magnetic materials design is discussed. Experimental magnetic and structural properties of a Gadolinium single crystal are compared to RPS-based calculations using microscopic parameters obtained from Density Functional Theory.

Acessibilidade no ambiente escolar: reflexões com base no estudo de duas escolas municipais de Natal-RN

This work was originated through the results of the analysis of the services for the needs of people with disabilities that were permitted by the physical space of two schools of the municipality of Natal/RN. The general objective/goal was to subsidize the elaboration of alternatives for the planning of environments that could be used by any person. The study used the empirical research through the adoption of a multimethod approach including: (i) technical visits oriented by the NBR 9050, (ii) contact with users that have reduced mobility (visually impaired and wheelchair or crutch users) through escorted travels and interviews, and (iii) interview with school managers. The evidence from the research, even though with significant development of laws that guarantee people with disabilities their right to citizenship, the physical environment of our schools still present with many obstacles that prevent the mobility of people with disabilities which proves their lack of readiness to accommodate them. Therefore, the actions taken to address the accessibility has been the adoption of temporary solutions that makes the adaptation more difficult, adds obstacles and reinforces the undesirable segregation, however still very present in our society. Finally, there is the indication that in order to achieve the spatial configuration that promotes social contact and integration in between the persons with different physical status, it is necessary to completely comprehend the activities developed in each space, from the conception of the equipment to the individual learning needs, having in mind creating environments that stimulates the execution of the tasks in an independent manner without the assistance of others. The inclusion regarding attention to accessibility in the decision making process, directed to the arquitectural and urban project, would decrease the constant need to redevelop and adapt spaces, and should be definitely incorporated as an important component in the production of space

Controladores repetitivos aplicados a filtros ativos de potência sob variações de carga e de frequência da rede

This work presents the development and modification of techniques to reduce the effects of load variation and mains frequency deviation in repetitive controllers applied to active power filters. To minimize the effects of aperiodic signals resulting from the connection or disconnection of non-linear loads is developed a technique which recognizes linear and nonlinear loads, and operates to reset the controller only when the error due to the transition of considerable value, and the transition is from non-linear to linear load. An algorithm to adapt the gain of the repetitive controller, based on a sigmoid function adaptation, in order to minimize the effects caused by random noise in the measurement system is also used. This work also analyzes the effects of frequency variation and presents the main methods to cope with this situation. Some solutions are the change in the number of samples per period and the variation of the sampling rate. The first has the advantage of using linear design techniques and results in a time invariant system. The second method changes the sampling frequency and leads to a time variant system that demands a difficult analysis of stability. The proposed algorithms were tested using the methods of truncation of the number of samples and the method of changing the sampling rate of the system to compensate possible frequency variations of the grid. Experimental results are presented to validate the proposal.

Comunidades zooplanctônicas como bioindicadoras da qualidade da água de quatro reservatórios da região semi-árida do Rio Grande do Norte

The response of zooplankton assemblages to variations in the water quality of four man-made lakes, caused by eutrophication and siltation, was investigated by means of canonical correspondence analysis. Monte Carlo simulations using the CCA eingenvalues as test statistics revealed that changes in zooplankton species composition along the environmental gradients of trophic state and abiogenic turbidity were highly significant. The species Brachionus calyciflorus, Thermocyclops sp. and Argyrodiaptomus sp. were good indicators of eutrophic conditions while the species Brachionus dolabratus, Keratella tropica and Hexarthra sp. were good indicators of high turbidity due to suspended sediments. The rotifer genus Brachionus was the most species-rich taxon, comprising five species which were associated with different environmental conditions. Therefore, we tested whether this genus alone could potentially be a better biological indicator of these environmental gradients than the entire zooplankton assemblages or any other random set of five species. The ordination results show that the five Brachionus species alone did not explain better the observed pattern of environmental variation than most random sets of five species. Therefore, this genus could not be selected as a target taxon for more intensive environmental monitoring as has been previously suggested by Attayde and Bozelli (1998). Overall, our results show that changes in the water quality of man-made lakes in a tropical semi-arid region have significant effects on the structure of zooplankton assemblages that can potentially affect the functioning of these ecosystems

Navegando a tempestade num copo de álcool: locus de controlo de saúde e depressão em alcoólicos em tratamento

Dissertação de Mestrado apresentada no Instituto Superior de Psicologia Aplicada para obtenção de grau de Mestre na especialidade de Psicologia Clínica

Os critérios de gatekeeping que evitam que uma lovebrand se transforme numa hatebrand

A relação marca/consumidor é importante e, atualmente, com a evolução tecnológica e com a disseminação das redes sociais, a sua importância subiu de nível pois o meio online permite que os consumidores estejam mais informados e tenham mais consciência das diversas opções que existem no mercado. Como tal, as marcas aproveitam as redes sociais, tais como o Facebook, para se fazerem notar, para mostrarem o seu lado mais humano e assim estabelecer comunicação com os utilizadores de forma a criar ou manter uma relação mais íntima com o mesmo. Contudo, a liberdade de expressão que existe nas redes sociais nem sempre é favorável às marcas, o que faz com que estas optem por utilizar critérios de gatekeeping para filtrar alguns conteúdos. O que se pretende deste estudo não experimental de tipo exploratório e de método qualitativo, é aferir que critérios de gatekeeping é que são mais suscetíveis de serem utilizados pelas marcas, de forma a evitarem que a relação forte que detêm com o consumidor fique comprometida e manchada pelo ódio e, consequentemente, perceber como é feita a gestão das próprias páginas de Facebook. O objeto do estudo em causa envolve, assim, duas empresas do setor eletrónico que são concorrentes diretas e que têm consumidores muito dedicados e que foram selecionadas através de um método de amostragem não aleatório intencional.

Estudo dos determinantes do crescimento das empresas familiares portuguesas

No presente estudo procuramos analisar os determinantes do crescimento das empresas familiares portuguesas, através de uma amostra de empresas familiares membros da Associação de Empresas Familiares, durante o período de 2006 a 2014. Com vista ao teste das hipóteses em estudo foram utilizados dados em painel, com modelos de efeitos fixo e aleatório. A variável dependente definida foi o crescimento das vendas. As variáveis independentes definidas foram: dimensão; idade; endividamento; endividamento de curto prazo; endividamento de médio longo prazo; produtividade da mão-de-obra; estrutura do ativo; variável dummy da crise financeira; variável dummy da administração pertencer à família; e variável dummy do género do administrador. Os resultados obtidos confirmam a dimensão, a idade e o endividamento como determinantes do crescimento; ABSTRACT: In the present study we analyzed the determinants of growth of family businesses through a sample of family businesses members of the Family Business Association, during the period between 2006 and 2014. In order to test the hypotheses under study were used panel data, with models of fixed and random effects. The Sales growth was defined as the dependent variable. The independent variables were defined: size; age; debt; short-term debt; medium and long term debt; labor productivity; asset structure; dummy variable of the financial crisis; dummy administration belong to the family; and dummy administrator gender variable. The results confirm the size, age, and debt as determinants of growth.

Análise experimental do efeito da diversificação em carteiras de ações: a relação entre risco e quantidade de ativos sob a ótica da estratégia ingênua

The objective is to analyze the relationship between risk and number of stocks of a portfolio for an individual investor when stocks are chosen by "naive strategy". For this, we carried out an experiment in which individuals select actions to reproduce this relationship. 126 participants were informed that the risk of first choice would be an asset average of all standard deviations of the portfolios consist of a single asset, and the same procedure should be used for portfolios composed of two, three and so on, up to 30 actions . They selected the assets they want in their portfolios without the support of a financial analysis. For comparison we also tested a hypothetical simulation of 126 investors who selected shares the same universe, through a random number generator. Thus, each real participant is compensated for random hypothetical investor facing the same opportunity. Patterns were observed in the portfolios of individual participants, characterizing the curves for the components of the samples. Because these groupings are somewhat arbitrary, it was used a more objective measure of behavior: a simple linear regression for each participant, in order to predict the variance of the portfolio depending on the number of assets. In addition, we conducted a pooled regression on all observations by analyzing cross-section. The result of pattern occurs on average but not for most individuals, many of which effectively "de-diversify" when adding seemingly random bonds. Furthermore, the results are slightly worse using a random number generator. This finding challenges the belief that only a small number of titles is necessary for diversification and shows that there is only applicable to a large sample. The implications are important since many individual investors holding few stocks in their portfolios

Contribuições para a deteção automática de fratiras ósseas em imagens de ultrassom

Dissertação de Mestrado, Engenharia Eletrónica e Telecomunicações, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2014

Visitabilidade-vivenciabilidade em assentamentos informais : um estudo da acessibilidade de percursos urbanos no Conjunto Santa Terezinha em Fortaleza-CE

This research approaches the issue of accessibility in informal settlements, seeking for the challenges and limits defined by informal urban settings, about the application of accessibility parameters. Take the empirical universe as the Conjunto Santa Terezinha, located in Fortaleza- Ce. Initially, the study presents a reflection about the housing issue in Brazil and the informal settlementes in view of the Right to the City. In this sense, the main references are, the works of Suzanne Pasternak (2008), Nabil Bonduki (1998) and Erminia Maricato (1996-97), among others. Follows with the discussion of the concepts and classifications of this type of settlement, making a content analysis of legislation and regulations relating to accessibility and proposed the discussion of the accessible route as the right strategy for the city. In another step, the methodology of 'walking together' created by Dischinger (2000) was applied in a passage previously chosen, which the researcher follows the disabled person during the journey through city making records like photos and video. The comments and perceptions are compared to the spatial analysis of urban morphology, made from the method of Del Rio (1990) and Panerai (2006), and the parameters of NBR 9050. Knowledge of the area is enriched by the methodology of the production of space made by Henri Lefebvre in his book 'The production of space' (1974) with these categories: space conceived, perceived and lived. Another key reference of this author it s the book 'The Right to the City' (991), which allowed in-depth reflections on the social function of town. In conclusion, the study finds that to guarantee a minimum access conditions in informal sittlements it´s necessary to know the specifics of their morphology, their relations and urban practices in view of the visitability- experiencebility, describing it as complementary concepts

Image summarisation: human action description from static images

Dissertação de Mestrado, Processamento de Linguagem Natural e Indústrias da Língua, Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, 2014

Jerónimo Martins and internal social responsibility : a case study on employee awareness

Mestrado em Ciências Empresariais

Acessibilidade no ambiente escolar: reflexões com base no estudo de duas escolas municipais de Natal-RN

This work was originated through the results of the analysis of the services for the needs of people with disabilities that were permitted by the physical space of two schools of the municipality of Natal/RN. The general objective/goal was to subsidize the elaboration of alternatives for the planning of environments that could be used by any person. The study used the empirical research through the adoption of a multimethod approach including: (i) technical visits oriented by the NBR 9050, (ii) contact with users that have reduced mobility (visually impaired and wheelchair or crutch users) through escorted travels and interviews, and (iii) interview with school managers. The evidence from the research, even though with significant development of laws that guarantee people with disabilities their right to citizenship, the physical environment of our schools still present with many obstacles that prevent the mobility of people with disabilities which proves their lack of readiness to accommodate them. Therefore, the actions taken to address the accessibility has been the adoption of temporary solutions that makes the adaptation more difficult, adds obstacles and reinforces the undesirable segregation, however still very present in our society. Finally, there is the indication that in order to achieve the spatial configuration that promotes social contact and integration in between the persons with different physical status, it is necessary to completely comprehend the activities developed in each space, from the conception of the equipment to the individual learning needs, having in mind creating environments that stimulates the execution of the tasks in an independent manner without the assistance of others. The inclusion regarding attention to accessibility in the decision making process, directed to the arquitectural and urban project, would decrease the constant need to redevelop and adapt spaces, and should be definitely incorporated as an important component in the production of space

Simulação de fluxo de fluidos em meios porosos desordenados uma análise de efeito de escala na estimativa da permeabilidade e do coeficiente de arrasto

The present study provides a methodology that gives a predictive character the computer simulations based on detailed models of the geometry of a porous medium. We using the software FLUENT to investigate the flow of a viscous Newtonian fluid through a random fractal medium which simplifies a two-dimensional disordered porous medium representing a petroleum reservoir. This fractal model is formed by obstacles of various sizes, whose size distribution function follows a power law where exponent is defined as the fractal dimension of fractionation Dff of the model characterizing the process of fragmentation these obstacles. They are randomly disposed in a rectangular channel. The modeling process incorporates modern concepts, scaling laws, to analyze the influence of heterogeneity found in the fields of the porosity and of the permeability in such a way as to characterize the medium in terms of their fractal properties. This procedure allows numerically analyze the measurements of permeability k and the drag coefficient Cd proposed relationships, like power law, for these properties on various modeling schemes. The purpose of this research is to study the variability provided by these heterogeneities where the velocity field and other details of viscous fluid dynamics are obtained by solving numerically the continuity and Navier-Stokes equations at pore level and observe how the fractal dimension of fractionation of the model can affect their hydrodynamic properties. This study were considered two classes of models, models with constant porosity, MPC, and models with varying porosity, MPV. The results have allowed us to find numerical relationship between the permeability, drag coefficient and the fractal dimension of fractionation of the medium. Based on these numerical results we have proposed scaling relations and algebraic expressions involving the relevant parameters of the phenomenon. In this study analytical equations were determined for Dff depending on the geometrical parameters of the models. We also found a relation between the permeability and the drag coefficient which is inversely proportional to one another. As for the difference in behavior it is most striking in the classes of models MPV. That is, the fact that the porosity vary in these models is an additional factor that plays a significant role in flow analysis. Finally, the results proved satisfactory and consistent, which demonstrates the effectiveness of the referred methodology for all applications analyzed in this study.

Comunidades zooplanctônicas como bioindicadoras da qualidade da água de quatro reservatórios da região semi-árida do Rio Grande do Norte

The response of zooplankton assemblages to variations in the water quality of four man-made lakes, caused by eutrophication and siltation, was investigated by means of canonical correspondence analysis. Monte Carlo simulations using the CCA eingenvalues as test statistics revealed that changes in zooplankton species composition along the environmental gradients of trophic state and abiogenic turbidity were highly significant. The species Brachionus calyciflorus, Thermocyclops sp. and Argyrodiaptomus sp. were good indicators of eutrophic conditions while the species Brachionus dolabratus, Keratella tropica and Hexarthra sp. were good indicators of high turbidity due to suspended sediments. The rotifer genus Brachionus was the most species-rich taxon, comprising five species which were associated with different environmental conditions. Therefore, we tested whether this genus alone could potentially be a better biological indicator of these environmental gradients than the entire zooplankton assemblages or any other random set of five species. The ordination results show that the five Brachionus species alone did not explain better the observed pattern of environmental variation than most random sets of five species. Therefore, this genus could not be selected as a target taxon for more intensive environmental monitoring as has been previously suggested by Attayde and Bozelli (1998). Overall, our results show that changes in the water quality of man-made lakes in a tropical semi-arid region have significant effects on the structure of zooplankton assemblages that can potentially affect the functioning of these ecosystems