965 resultados para Context models
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Mestrado em Gestão e Empreendedorismo
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The problem of providing a hybrid wired/wireless communications for factory automation systems is still an open issue, notwithstanding the fact that already there are some solutions. This paper describes the role of simulation tools on the validation and performance analysis of two wireless extensions for the PROFIBUS protocol. In one of them, the Intermediate Systems, which connect wired and wireless network segments, operate as repeaters. In the other one the Intermediate Systems operate as bridge. We also describe how the analytical analysis proposed for these kinds of networks can be used for the setting of some network parameters and for the guaranteeing real-time behaviour of the system. Additionally, we also compare the bridge-based solution simulation results with the analytical results.
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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Hidráulica
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Existing work in the context of energy management for real-time systems often ignores the substantial cost of making DVFS and sleep state decisions in terms of time and energy and/or assume very simple models. Within this paper we attempt to explore the parameter space for such decisions and possible constraints faced.
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The workforce in organizations today is becoming increasingly diverse. Consequently the role of diversity management is heavily discussed with respect to the question how diversity influences the productivity of a group. Empirical studies show that on one hand there is a potential for increasing productivity but on the other hand it might be as well that conflicts arise due to the heterogeneity of the group. Usually according empirical studies are based on interviews, questionnaires and/or observations. These methods imply that answers are highly selective and filtered. In order to make the invisible visible, to have access to mental models of team members the paper will present an empirical study on the self-understanding of groups based on an innovative research method, called “mind-scripting”.
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This paper provides a longitudinal, empirical view of the multifaceted and reciprocal processes of organizational learning in a context of self-managed teams. Organizational learning is seen as a social construction between people and actions in a work setting. The notion of learning as situated (Brown & Duguid 1989, Lave& Wenger 1991, Gherardi & al. 1998, Easterby-Smith & Araujo 1999, Abma 2003) opens up the possibility for placing the focus of research on learning in the community rather than in individual learning processes. Further, in studying processes in their social context, we cannot avoid taking power relations into consideration (Contu & Willmott 2003). The study is based on an action research with a methodology close to the ‘democratic dialogue’ presented by Gustavsen (2001). This gives a ground for research into how the learning discourse developed in the case study organization over a period of 5 years, during which time the company abandoned a middle management level of hierarchy and the teams had to figure out how to work as self-managed units. This paper discusses the (re)construction of power relations and its role in organizational learning. Power relations are discussed both in vertical and horizontal work relations. A special emphasis is placed on the dialectic between managerial aims and the space for reflection on the side of employees. I argue that learning is crucial in the search for the limits for empowerment and that these limits are negotiated both in actions and speech. This study unfolds a purpose-oriented learning process, constructing an open dialogue, and describes a favourable context for creative, knowledge building communities.
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The use of bit error models in communication simulation has been widely studied. In this technical report we present three models: the Independent Channel Model; the Gilbert-Elliot Model and the Burst-Error Periodic Model.
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Doctoral Thesis in Information Systems and Technologies Area of Engineering and Manag ement Information Systems
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In this thesis we implement estimating procedures in order to estimate threshold parameters for the continuous time threshold models driven by stochastic di®erential equations. The ¯rst procedure is based on the EM (expectation-maximization) algorithm applied to the threshold model built from the Brownian motion with drift process. The second procedure mimics one of the fundamental ideas in the estimation of the thresholds in time series context, that is, conditional least squares estimation. We implement this procedure not only for the threshold model built from the Brownian motion with drift process but also for more generic models as the ones built from the geometric Brownian motion or the Ornstein-Uhlenbeck process. Both procedures are implemented for simu- lated data and the least squares estimation procedure is also implemented for real data of daily prices from a set of international funds. The ¯rst fund is the PF-European Sus- tainable Equities-R fund from the Pictet Funds company and the second is the Parvest Europe Dynamic Growth fund from the BNP Paribas company. The data for both funds are daily prices from the year 2004. The last fund to be considered is the Converging Europe Bond fund from the Schroder company and the data are daily prices from the year 2005.
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OBJECTIVE To identify independent risk factors for non-breastfeeding within the first hour of life.METHODS A systematic review of Medline, LILACS, Scopus, and Web of Science electronic databases, till August 30, 2013, was performed without restrictions on language or date of publishing. Studies that used regression models and provided adjusted measures of association were included. Studies in which the regression model was not specified or those based on specific populations regarding age or the presence of morbidities were excluded.RESULTS The search resulted in 155 articles, from which 18 met the inclusion criteria. These were conducted in Asia (9), Africa (5), and South America (4), between 1999 and 2013. The prevalence of breastfeeding within the first hour of life ranged from 11.4%, in a province of Saudi Arabia, to 83.3% in Sri Lanka. Cesarean delivery was the most consistent risk factor for non-breastfeeding within the first hour of life. “Low family income”, “maternal age less than 25 years”, “low maternal education”, “no prenatal visit”, “home delivery”, “no prenatal guidance on breastfeeding” and “preterm birth” were reported as risk factors in at least two studies.CONCLUSIONS Besides the hospital routines, indicators for low socioeconomic status and poor access to health services were also identified as independent risk factors for non-breastfeeding within the first hour of life. Policies to promote breastfeeding, appropriate to each context, should aim to reduce inequalities in health.
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Leaves are mainly responsible for food production in vascular plants. Studying individual leaves can reveal important characteristics of the whole plant, namely its health condition, nutrient status, the presence of viruses and rooting ability. One technique that has been used for this purpose is Electrical Impedance Spectroscopy, which consists of determining the electrical impedance spectrum of the leaf. In this paper we use EIS and apply the tools of Fractional Calculus to model and characterize six species. Two modeling approaches are proposed: firstly, Resistance, Inductance, Capacitance electrical networks are used to approximate the leaves’ impedance spectra; afterwards, fractional-order transfer functions are considered. In both cases the model parameters can be correlated with physical characteristics of the leaves.
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Dissertação apresentada para a obtenção do Grau de Doutor em Informática pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
Impact of a price-maker pumped storage hydro unit on the integration of wind energy in power systems
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The increasing integration of larger amounts of wind energy into power systems raises important operational issues, such as the balance between power generation and demand. The pumped storage hydro (PSH) units are one possible solution to mitigate this problem, once they can store the excess of energy in the periods of higher generation and lower demand. However, the behaviour of a PSH unit may differ considerably from the expected in terms of wind power integration when it operates in a liberalized electricity market under a price-maker context. In this regard, this paper models and computes the optimal PSH weekly scheduling in a price-taker and price-maker scenarios, either when the PSH unit operates in standalone and integrated in a portfolio of other generation assets. Results show that the price-maker standalone PSH will integrate less wind power in comparison with the price-taker situation. Moreover, when the PSH unit is integrated in a portfolio with a base load power plant, the role of the price elasticity of demand may completely change the operational profile of the PSH unit. (C) 2014 Elsevier Ltd. All rights reserved.
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Not just with the emergence but also with the growing of the electronic market, that is, the growth of online suppliers of services and products and Internet users (potential consumers), the necessary conditions to the affirmation of the agile/virtual enterprises (A/VE) as a present and future enterprise organizational model are created. In this context, it is our understanding that the broker may have an important role in its development, namely, if the broker performs functions for the A/VE with better efficacy and efficiency. In this article, we will present first a revision of the broker’s models in a structured form. We present a taxonomy of possible broker’s functions for the broker’s actuation near the A/VE and then the classification of the literature broker’s models. This classification will permit an analysis of a broker’s model and establish a mainframe for our broker’s model according to the BM_Virtual Enterprise Architecture Reference Model (BM_VEARM).
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A Formação Contínua em Contexto de Prática Efectiva foi um modelo de formação contínua implementado em cinco Centros de Formação de Associações de Escolas do Distrito de Setúbal. Após um ano da sua implementação, optou-se pela realização de um estudo de avaliação que utilizou para recolha de dados o inquérito por questionário. Foi dirigido aos professores a leccionar nas escolas de cada centro. A análise englobou o nível de satisfação dos docentes participantes no estudo, relativamente ao tipo de Formação Contínua que realizaram nos últimos anos e permitiu: conhecer as competências e conhecimentos de base tecnológica dos professores; conhecer as suas necessidades de formação futuras e analisar como são assimiladas pelos professores as novas formas de Formação Contínua quer de carácter misto, presencial e a distância (“blended-learning”) quer online. The Continuing Professional Development in the context of effective practice was a model of teachers’ training implemented in five Schools Associations’ Training Centers in the District of Setúbal. After a year of its implementation it took place an assessment study using a survey, directed to the teachers that teach in the schools of the five Centers. The analysis approached teachers’ level of satisfaction participating in the study about the type of Continuing Training in which they enrolled in recent years; it allowed to know teachers’ ICT skills and knowledge; it allowed to identify future training needs and examine how new models of Continuing Training are understood by teachers in either blended or distance learning.