972 resultados para Uniform ergodicity


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Mathematical models and statistical analysis are key instruments in soil science scientific research as they can describe and/or predict the current state of a soil system. These tools allow us to explore the behavior of soil related processes and properties as well as to generate new hypotheses for future experimentation. A good model and analysis of soil properties variations, that permit us to extract suitable conclusions and estimating spatially correlated variables at unsampled locations, is clearly dependent on the amount and quality of data and of the robustness techniques and estimators. On the other hand, the quality of data is obviously dependent from a competent data collection procedure and from a capable laboratory analytical work. Following the standard soil sampling protocols available, soil samples should be collected according to key points such as a convenient spatial scale, landscape homogeneity (or non-homogeneity), land color, soil texture, land slope, land solar exposition. Obtaining good quality data from forest soils is predictably expensive as it is labor intensive and demands many manpower and equipment both in field work and in laboratory analysis. Also, the sampling collection scheme that should be used on a data collection procedure in forest field is not simple to design as the sampling strategies chosen are strongly dependent on soil taxonomy. In fact, a sampling grid will not be able to be followed if rocks at the predicted collecting depth are found, or no soil at all is found, or large trees bar the soil collection. Considering this, a proficient design of a soil data sampling campaign in forest field is not always a simple process and sometimes represents a truly huge challenge. In this work, we present some difficulties that have occurred during two experiments on forest soil that were conducted in order to study the spatial variation of some soil physical-chemical properties. Two different sampling protocols were considered for monitoring two types of forest soils located in NW Portugal: umbric regosol and lithosol. Two different equipments for sampling collection were also used: a manual auger and a shovel. Both scenarios were analyzed and the results achieved have allowed us to consider that monitoring forest soil in order to do some mathematical and statistical investigations needs a sampling procedure to data collection compatible to established protocols but a pre-defined grid assumption often fail when the variability of the soil property is not uniform in space. In this case, sampling grid should be conveniently adapted from one part of the landscape to another and this fact should be taken into consideration of a mathematical procedure.

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Mestrado em Gestão e Avaliação de Tecnologias em Saúde

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Earthquakes are associated with negative events, such as large number of casualties, destruction of buildings and infrastructures, or emergence of tsunamis. In this paper, we apply the Multidimensional Scaling (MDS) analysis to earthquake data. MDS is a set of techniques that produce spatial or geometric representations of complex objects, such that, objects perceived to be similar/distinct in some sense are placed nearby/distant on the MDS maps. The interpretation of the charts is based on the resulting clusters since MDS produces a different locus for each similarity measure. In this study, over three million seismic occurrences, covering the period from January 1, 1904 up to March 14, 2012 are analyzed. The events, characterized by their magnitude and spatiotemporal distributions, are divided into groups, either according to the Flinn–Engdahl seismic regions of Earth or using a rectangular grid based in latitude and longitude coordinates. Space-time and Space-frequency correlation indices are proposed to quantify the similarities among events. MDS has the advantage of avoiding sensitivity to the non-uniform spatial distribution of seismic data, resulting from poorly instrumented areas, and is well suited for accessing dynamics of complex systems. MDS maps are proven as an intuitive and useful visual representation of the complex relationships that are present among seismic events, which may not be perceived on traditional geographic maps. Therefore, MDS constitutes a valid alternative to classic visualization tools, for understanding the global behavior of earthquakes.

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The knowledge of the anisotropic properties beneath the Iberian Peninsula and Northern Morocco has been dramatically improved since late 2007 with the analysis of the data provided by the dense TopoIberia broadband seismic network, the increasing number of permanent stations operating in Morocco, Portugal and Spain, and the contribution of smaller scale/higher resolution experiments. Results from the two first TopoIberia deployments have evidenced a spectacular rotation of the fast polarization direction (FPD) along the Gibraltar Arc, interpreted as an evidence of mantle flow deflected around the high velocity slab beneath the Alboran Sea, and a rather uniform N100 degrees E FPD beneath the central Iberian Variscan Massif, consistent with global mantle flow models taking into account contributions of surface plate motion, density variations and net lithosphere rotation. The results from the last Iberarray deployment presented here, covering the northern part of the Iberian Peninsula, also show a rather uniform FPD orientation close to N100 degrees E, thus confirming the previous interpretation globally relating the anisotropic parameters to the LPO of mantle minerals generated by mantle flow at asthenospheric depths. However, the degree of anisotropy varies significantly, from delay time values of around 0.5 s beneath NW Iberia to values reaching 2.0 sin its NE comer. The anisotropic parameters retrieved from single events providing high quality data also show significant differences for stations located in the Variscan units of NW Iberia, suggesting that the region includes multiple anisotropic layers or complex anisotropy systems. These results allow to complete the map of the anisotropic properties of the westernmost Mediterranean region, which can now be considered as one of best constrained regions worldwide, with more than 300 sites investigated over an area extending from the Bay of Biscay to the Sahara platform. (C) 2015 Elsevier B.V. All rights reserved.

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RESUMO: Com o presente estudo pretendemos identificar a sobrecarga resultante do envolvimento familiar com os doentes portadores de VIH/SIDA. Numa breve introdução teórica, procedemos à revisão dos conceitos sobrecarga familiar e dos sentimentos/emoções vivenciados pelos prestadores de cuidados. Metodologia: Estudo do tipo descritivo e exploratório, com uma amostra de 51 indivíduos, cuja finalidade consiste na caracterização dos prestadores de cuidados familiares a doentes com VIH/SIDA. Objectivos: Identificar quem o doente com VIH/SIDA, considera ser a pessoa significativa nos cuidados informais. Caracterizar, do ponto de vista sócio-demográfico, os doentes e os prestadores de cuidados familiares. Identificar sentimentos e emoções de vivências, que justifiquem o sofrimento emocional e as repercussões na sobrecarga familiar nos prestadores de cuidados informais. Instrumentos: Na avaliação da sobrecarga familiar, utilizámos o Questionário de Problemas Familiares”- FPQ (Family Problemas Questionnaire). Para identificação dos Acontecimentos de Vida, adoptámos a escala de Holmes e Rahe (Life Events); Para identificação do estrato social escolhemos escala de Graffar. Finalmente, para a caracterização sócio-demografica concebemos dois questionários: um dirigido aos doentes e o outro aos prestadores de cuidados informais. Conclusões: A sobrecarga da doença VIH/SIDA, nos prestadores de cuidados familiares, não é uniforme nas diferentes dimensões. A dimensão sobrecarga subjectiva é superior à objectiva. O suporte social revela-se fraco, relacionado com as perdas familiares, devidas a morte, pelas relações familiares disfuncionais, entre os membros da família, pela falta de apoio e informação dos técnicos de saúde. O sexo feminino é predominante nos cuidadores. As mães e esposas são o grau de parentesco dominante. Os solteiros são o grupo mais afectado pelo VIH/SIDA. Os cuidadores apresentam idade superior à dos doentes. O estrato social preponderante é o médio baixo e o baixo. Os familiares, apesar da atitude negativa dos doentes perante os cuidadores, mantêm-se envolvidos. Segundo a avaliação multiaxial proposta pelo DM-IV, constatámos, ao nível do eixo I, sintomatologia clínica do tipo das perturbações depressivas e perturbações da ansiedade. No eixo IV, os cuidadores evidenciam problemas psicossociais e ambientais, nomeadamente nas categorias problemas com o grupo de apoio primário, problemas relacionados como grupo social, problemas educacionais, problemas de alojamento, problemas económicos. Os problemas relacionados com o grupo de apoio primário, são os que mais parecem contribuir para os problemas psicossociais e ambientais.---------------------------------------ABSTRACT: This study wants to describe several problems as a result of the family’s relationship with HIV/AIDS patients, like overload. In a brief theoric introduction, we made a small revision about the concepts of family’s overload, and feelings or emotions that have been lived by the people who provide cares to the patients with this chronic disease. Methodology: This is a describing and exploratory study, with a sample with 51 individuals, with the aim to characterize the people inside the family who give care HIV/AIDS patients. Aim: To identify who are the most important people in informal cares from the patient perspective. To characterize, in a social-demographic point of view, patients and the people who take care of them. To identify feelings and emotions that could explain an emotional suffer, and some causes in the family burden. Means: to evaluate the family’s overload we used the Family Problems Questionnaire (FPQ). To identify life events we adopted the Holmes and Rahe scale. To identify the social stratum we used the Graffer scale. Finally to do a socio-economic characterization we did two kinds of questionnaire, the first one was directed for the patients, and the second one was chosen for the people who give care. Conclusions: The HIV/AIDS disease burden on the people who takes familiar cares isn’t uniform on several areas that we studied. The subjective overload it is superior to the objective. The social support is weak and poor, and related with family losses by dead, dysfunctional family relationships, and the lack of support and information by the medical staff. Mothers and wives are the dominant relative degree. And the singles are the major group with HIV/AIDS disease. The people who take care are usually older than the sick. The major social status is low or medium-low. The relatives keep evolved though the negative attitude of the sick. According with the evaluation multiaxial proposed by the DM-IV, in axle 1 we note clinic sintomatologic belonging to the type depressive perturbations and perturbations of the anxiety. Regarding with axle IV the caretakers show up psycho-social and environmental problems, namely on the categories: problems with the primary support group and problems related as social group, educational problems, accommodation problems and.

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In recent years, mobile learning has emerged as an educational approach to decrease the limitation of learning location and adapt the teaching-learning process to all type of students. However, the large number and variety of Web-enabled devices poses challenges for Web content creators who want to automatic get the delivery context and adapt the content to mobile devices. This paper studies several approaches to adapt the learning content to mobile phones. It presents an architecture for deliver uniform m-Learning content to students in a higher School. The system development is organized in two phases: firstly enabling the educational content to mobile devices and then adapting it to all the heterogeneous mobile platforms. With this approach, Web authors will not need to create specialized pages for each kind of device, since the content is automatically transformed to adapt to any mobile device capabilities from WAP to XHTML MP-compliant devices.

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In order to correctly assess the biaxial fatigue material properties one must experimentally test different load conditions and stress levels. With the rise of new in-plane biaxial fatigue testing machines, using smaller and more efficient electrical motors, instead of the conventional hydraulic machines, it is necessary to reduce the specimen size and to ensure that the specimen geometry is appropriate for the load capacity installed. At the present time there are no standard specimen's geometries and the indications on literature how to design an efficient test specimen are insufficient. The main goal of this paper is to present the methodology on how to obtain an optimal cruciform specimen geometry, with thickness reduction in the gauge area, appropriate for fatigue crack initiation, as a function of the base material sheet thickness used to build the specimen. The geometry is optimized for maximum stress using several parameters, ensuring that in the gauge area the stress distributions on the loading directions are uniform and maximum with two limit phase shift loading conditions (delta = 0 degrees and (delta = 180 degrees). Therefore the fatigue damage will always initiate on the center of the specimen, avoiding failure outside this region. Using the Renard Series of preferred numbers for the base material sheet thickness as a reference, the reaming geometry parameters are optimized using a derivative-free methodology, called direct multi search (DMS) method. The final optimal geometry as a function of the base material sheet thickness is proposed, as a guide line for cruciform specimens design, and as a possible contribution for a future standard on in-plane biaxial fatigue tests

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An improved class of nonlinear bidirectional Boussinesq equations of sixth order using a wave surface elevation formulation is derived. Exact travelling wave solutions for the proposed class of nonlinear evolution equations are deduced. A new exact travelling wave solution is found which is the uniform limit of a geometric series. The ratio of this series is proportional to a classical soliton-type solution of the form of the square of a hyperbolic secant function. This happens for some values of the wave propagation velocity. However, there are other values of this velocity which display this new type of soliton, but the classical soliton structure vanishes in some regions of the domain. Exact solutions of the form of the square of the classical soliton are also deduced. In some cases, we find that the ratio between the amplitude of this wave and the amplitude of the classical soliton is equal to 35/36. It is shown that different families of travelling wave solutions are associated with different values of the parameters introduced in the improved equations.

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Apresentação realizada no OH&S Forum 2011 - International Forum on Occupational Health and Safety: Policies, profiles and services, na Finlândia de, 20 a 22 Junho de 2011.

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Cosmic microwave background (CMB) radiation is the imprint from an early stage of the Universe and investigation of its properties is crucial for understanding the fundamental laws governing the structure and evolution of the Universe. Measurements of the CMB anisotropies are decisive to cosmology, since any cosmological model must explain it. The brightness, strongest at the microwave frequencies, is almost uniform in all directions, but tiny variations reveal a spatial pattern of small anisotropies. Active research is being developed seeking better interpretations of the phenomenon. This paper analyses the recent data in the perspective of fractional calculus. By taking advantage of the inherent memory of fractional operators some hidden properties are captured and described.

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Mestrado em Engenharia Química - Ramo Optimização Energética na Indústria Química

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A seroepidemiologic survey about hepatitis A virus (HAV) infection was carried out in a group comprising 310 children, ranging in age from 3 months to 9 years, from day-care centers, in Goiania, a middle sized city in the central region of Brazil. The biomarkers employed in the investigation of previous infection include total IgG and IgM anti-HAV antibodies, and for the detection of more recent infection, IgM anti-HAV antibodies were analyzed. The study was performed in 1991 and 1992. According to the results, 69.7% of the children presented total IgG/IgM anti-HAV antibodies, with 60% of the group in the age range of 1 to 3 years. Among 10 day-care centers analyzed, the prevalence of the biomarker IgM anti-HAV was 3.2%, with an uniform distribution of the cases in the group of children ranging in age from 1 to 4 years. Multi-variate analysis was performed to investigate the sociodemographic factors that could influence the results. It was verified that the risk for the infection increased with the length of the attendance in the day-care centers, i.e., the risk for children with attendance of one year or more was 4.7 times higher, when compared with children with one month attendance (CI 95% 2.3-9.9). According to the results, hepatitis A is an endemic infection in day-care centers in the study area. The length of attendance in the day-care settings was demonstrated to be a risk factor for the HAV infection. Such findings suggest that if hepatits A vaccination becomes available as a routine policy in our region, the target group should be children under one year. Moreover, those children should receive the vaccine before they start to attend the day-care centers.

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A crescente evolução na tecnologia das juntas coladas conferiu um potencial atractivo às ligações adesivas, com aplicações nas mais variadas indústrias. Isto deve-se não só aos aspetos económicos, tais como a melhoria da cadência de produção mas também à resistência mecânica que estas proporcionam. A possibilidade de ligar facilmente materiais distintos, a distribuição mais uniforme das tensões, a melhor resistência à fadiga e a elevada capacidade de amortecimento de vibrações estão entre as principais vantagens da utilização deste tipo de ligação. Estas propriedades transformam as juntas coladas numas das preferidas no momento de seleção de meios de união. O trabalho desenvolvido nesta dissertação enquadra-se no âmbito das ligações adesivas e tem como principais objetivos a produção de uma ferramenta para a produção de provetes de adesivo, assim como a determinação das propriedades mecânicas à tração dos mesmos para testar o desempenho do molde fabricado. Para tal, utilizou-se um adesivo frágil (Araldite® AV 138), um dúctil (Araldite® 2015) e um muito dúctil (SikaForce® 7888). Paralelamente é selecionado o método mais adequado na obtenção destes provetes, designadamente escolhendo entre a moldação em molde aberto e a injeção em molde fechado. Com vista à obtenção dos provetes, foi projetado e construído um molde em aço. Recorrendo à máquina de tração Shimadzu AG – X 100, realizaram-se os respetivos ensaios de tração, para a determinação de todas as propriedades mecânicas dos adesivos. Para efeitos de comparação de resultados foram utilizados dois tipos de extensómetros, um mecânico e um ótico. Os resultados experimentais permitiram observar que a presença de vazios afetou especialmente a deformação de rotura e a tensão de rotura. Detetaram-se pequenas discordâncias, comparativamente com os estudos publicados, de algumas características mecânicas obtidas dos diversos adesivos utilizados. Constatou-se também um ligeiro desfasamento entre os valores adquiridos com os dois tipos de extensómetros utilizados.

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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores

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Robotica 2012: 12th International Conference on Autonomous Robot Systems and Competitions April 11, 2012, Guimarães, Portugal