992 resultados para Temporal aggregation


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Tese de doutoramento, Geografia (Geografia Física), Universidade de Lisboa, Instituto de Geografia e Ordenamento do Território, 2014

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Geographical and temporal variations in the start dates of grass pollen seasons are described for selected sites of the European Pollen Information Service. Daily average grass pollen counts are derived from Network sites in Finland, the Netherlands, Denmark, United Kingdom, Austria, Italy and Spain, giving a broad longitudinal transect over Western Europe. The study is part of a larger project that also examines annual and regional variations in the severity, timing of the peak and duration of the grass pollen seasons. For several sites, data are available for over twenty years enabling long term trends to be discerned. The analyses show notable contrasts in the progression of the seasons annually with differing lag times occurring between southern and northern sites in various years depending on the weather conditions. The patterns identified provide some insight into geographical differences and temporal trends in the incidence of pollinosis. The paper discusses the main difficulties involved in this type of analysis and notes possibilities for using data from the European Pollen Information service to construct pan European predictive models for pollen seasons.

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Tese de doutoramento, Informática (Ciências da Computação), Universidade de Lisboa, Faculdade de Ciências, 2015

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Detailed surveys of depth and velocity are undertaken to describe hydro-ecological status of rivers. Fieldwork for these surveys is time consuming and expensive. This paper aims to describe the methodology applied in order to determine the most suitable depth sampling strategy for effective field data collection and river representation in time and space at the Leigh Brook river site, Worcester, UK. The accuracy of three different sampling strategies for predicting depth at non-measured points has been compared and the mesohabitats that better characterise depth changes due to variations in discharge have been identified. The results show that depth changes due to discharge change are mainly located at shallow and deep glide mesohabitat types. The analysis for the comparison of sampling strategies indicates that grid sampling strategies give better results than regular transects. Since the results also show that higher errors in predictions are obtained in the deepest areas, higher sampling densities should be applied in these locations.

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This thesis takes a theoretical and practical approach to data visualization, focusing in particular on interactive timelines as a means to mapping historical/cultural narratives. It seeks to understand how timelines can efficiently communicate a historical narrative, enhancing the topic’s comprehension whilst relating it to the surrounding context. For this purpose, an interactive timeline on Design in Portugal from 1900 to present, was conceptualized and developed. The research adopted a descriptive methodology. The theoretical framework depicts the basic concepts, models and taxonomies associated to timelines, which derive from the main studies available on the matter. From this, a model for the analysis of three case studies – Idea Line (2002), The Path of Protest (2011) and British History Timeline (2006) – was proposed. The selection criteria shows that they refer to interactive timelines depicting a historical narrative, in addition to being as heterogeneous as possible with respect to the themes presented and conveyed purposes. The comparative analysis produced a set of thoughts, conclusions and principles, subsequently considered and applied in the development of the timeline presented. The results of this study point to the decisive role of visual setup of the time axis and user tasks in the interpretation of information. The effective implementation of the timeline Design in Portugal: from 1900 to present, contributes to the study of timelines as information devices with its own characteristics and capabilities, promotes associated research and theoretical systematization and, on a pragmatic note, helps creating the basis for the gathering, compilation and presentation of relevant information on design in Portugal, providing the academic and professional community with an effective tool for referring and learning

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AMPA receptors are glutamate-gated cation channels assembled from GluA1-4 subunits and have properties that are strongly dependent on the subunit composition. The subunits have different propensities to form homomeric or various heteromeric receptors expressed on cell surface, but the underlying mechanisms are still poorly understood. Here, we examined the biochemical basis for the poor ability of GluA3 subunits to form homomeric receptors, linked previously to two amino acid residues, Y454 and R461, in its ligand-binding domain (LBD). Surface expression of GluA3 was improved by co-assembly with GluA2 but not with stargazin, a trafficking chaperone and modulator of AMPA receptors. The secretion efficiency of GluA2 and GluA3 LBDs paralleled the transport difference between the respective full-length receptors and was similarly dependent on Y454/R461, but not on LBD stability. In comparison to GluA2, GluA3 homomeric receptors showed a strong and Y454/R461-dependent tendency to aggregate both in the macroscopic scale measured as lower solubility in nonionic detergent and in the microscopic scale evident as the preponderance of hydrodynamically large structures in density gradient centrifugation and native gel electrophoresis. We conclude that the impaired surface expression of homomeric GluA3 receptors is caused by nonproductive assembly and aggregation to which LBD residues Y454 and R461 strongly contribute. This aggregation inhibits the entry of newly synthesized GluA3 receptors to the secretory pathway.

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Existing Workflow Management Systems (WFMSs) follow a pragmatic approach. They often use a proprietary modelling language with an intuitive graphical layout. However the underlying semantics lack a formal foundation. As a consequence, analysis issues, such as proving correctness i.e. soundness and completeness, and reliable execution are not supported at design level. This project will be using an applied ontology approach by formally defining key terms such as process, sub-process, action/task based on formal temporal theory. Current business process modelling (BPM) standards such as Business Process Modelling Notation (BPMN) and Unified Modelling Language (UML) Activity Diagram (AD) model their constructs with no logical basis. This investigation will contribute to the research and industry by providing a framework that will provide grounding for BPM to reason and represent a correct business process (BP). This is missing in the current BPM domain, and may result in reduction of the design costs and avert the burden of redundant terms used by the current standards. A graphical tool will be introduced which will implement the formal ontology defined in the framework. This new tool can be used both as a modelling tool and at the same time will serve the purpose of validating the model. This research will also fill the existing gap by providing a unified graphical representation to represent a BP in a logically consistent manner for the mainstream modelling standards in the fields of business and IT. A case study will be conducted to analyse a catalogue of existing ‘patient pathways’ i.e. processes, of King’s College Hospital NHS Trust including current performance statistics. Following the application of the framework, a mapping will be conducted, and new performance statistics will be collected. A cost/benefits analysis report will be produced comparing the results of the two approaches.

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Existing Workflow Management Systems (WFMSs) follow a pragmatic approach. They often use a proprietary modelling language with an intuitive graphical layout. However the underlying semantics lack a formal foundation. As a consequence, analysis issues, such as proving correctness i.e. soundness and completeness, and reliable execution are not supported at design level. This project will be using an applied ontology approach by formally defining key terms such as process, sub-process, action/task based on formal temporal theory. Current business process modelling (BPM) standards such as Business Process Modelling Notation (BPMN) and Unified Modelling Language (UML) Activity Diagram (AD) model their constructs with no logical basis. This investigation will contribute to the research and industry by providing a framework that will provide grounding for BPM to reason and represent a correct business process (BP). This is missing in the current BPM domain, and may result in reduction of the design costs and avert the burden of redundant terms used by the current standards. A graphical tool will be introduced which will implement the formal ontology defined in the framework. This new tool can be used both as a modelling tool and at the same time will serve the purpose of validating the model. This research will also fill the existing gap by providing a unified graphical representation to represent a BP in a logically consistent manner for the mainstream modelling standards in the fields of business and IT. A case study will be conducted to analyse a catalogue of existing ‘patient pathways’ i.e. processes, of King’s College Hospital NHS Trust including current performance statistics. Following the application of the framework, a mapping will be conducted, and new performance statistics will be collected. A cost/benefits analysis report will be produced comparing the results of the two approaches.

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Introdução: A disfunção temporomandibular (DTM), de causa muscular, caracteriza-se por uma dor músculo-esquelética crónica, com sinais e sintomas específicos como a presença de Trigger Points (TrPs). Objetivo: Avaliar o efeito da Técnica de Inibição de Jones (TIJ) nos músculos masseter e temporal em indivíduos com DTM, e a identificação dos sinais e sintomas, a relação entre a severidade da DTM, a ansiedade e a qualidade de sono. Métodos: Estudo quasi-experimental, constituído por 16 indivíduos no grupo experimental (GE) e 17 grupo controle (GC). O grau de severidade foi avaliado pelo Índice de Helkimo e as alterações do sono pelo questionário de Pittsburgh sobre a qualidade do sono. Apenas o GE foi sujeito a uma TIJ nos TrPs latentes dos músculos masseter e temporal. Os dois grupos foram avaliados pré-intervenção (M0), pós-intervenção (M1) e 3 semanas após (M2), as amplitudes de movimento ativas de abertura, lateralidade direita/esquerda e protusão da boca bem como a dor (EVA) em repouso e na abertura máxima. Resultados: Foi possível observar que quanto maior o grau de DTM, maior a frequência de ansiedade e pior a qualidade do sono. Observou-se um decréscimo de TrPs, no GE, após a aplicação da técnica, principalmente no masseter. Não foi possível verificar diferenças inter-grupos. Contudo, observou-se no GE uma melhoria em todas as amplitudes avaliadas entre o M0 e o M2. Em relação à EVA em repouso e na abertura máxima, o GE demonstrou diminuição da dor no M1 e manteve valores inferiores no M2. Conclusão: Verifica-se uma diminuição dos TrPs, uma melhoria das amplitudes ativas bem como uma diminuição da dor após a aplicação da TIJ no GE. Já ao longo do tempo, o efeito é menos expressivo contudo observam-se valores inferiores comparativamente a M0.

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Renewable energy sources (RES) have unique characteristics that grant them preference in energy and environmental policies. However, considering that the renewable resources are barely controllable and sometimes unpredictable, some challenges are faced when integrating high shares of renewable sources in power systems. In order to mitigate this problem, this paper presents a decision-making methodology regarding renewable investments. The model computes the optimal renewable generation mix from different available technologies (hydro, wind and photovoltaic) that integrates a given share of renewable sources, minimizing residual demand variability, therefore stabilizing the thermal power generation. The model also includes a spatial optimization of wind farms in order to identify the best distribution of wind capacity. This methodology is applied to the Portuguese power system.

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As e-learning gradually evolved many specialized and disparate systems appeared to fulfil the needs of teachers and students, such as repositories of learning objects, authoring tools, intelligent tutors and automatic evaluators. This heterogeneity raises interoperability issues giving the standardization of content an important role in e-learning. This article presents a survey on current e-learning content aggregation standards focusing on their internal organization and packaging. This study is part of an effort to choose the most suitable specifications and standards for an e-learning framework called Ensemble defined as a conceptual tool to organize a network of e-learning systems and services for domains with complex evaluation.

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The positioning of the consumers in the power systems operation has been changed in the recent years, namely due to the implementation of competitive electricity markets. Demand response is an opportunity for the consumers’ participation in electricity markets. Smart grids can give an important support for the integration of demand response. The methodology proposed in the present paper aims to create an improved demand response program definition and remuneration scheme for aggregated resources. The consumers are aggregated in a certain number of clusters, each one corresponding to a distinct demand response program, according to the economic impact of the resulting remuneration tariff. The knowledge about the consumers is obtained from its demand price elasticity values. The illustrative case study included in the paper is based on a 218 consumers’ scenario.

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The implementation of competitive electricity markets has changed the consumers’ and distributed generation position power systems operation. The use of distributed generation and the participation in demand response programs, namely in smart grids, bring several advantages for consumers, aggregators, and system operators. The present paper proposes a remuneration structure for aggregated distributed generation and demand response resources. A virtual power player aggregates all the resources. The resources are aggregated in a certain number of clusters, each one corresponding to a distinct tariff group, according to the economic impact of the resulting remuneration tariff. The determined tariffs are intended to be used for several months. The aggregator can define the periodicity of the tariffs definition. The case study in this paper includes 218 consumers, and 66 distributed generation units.