966 resultados para Local likelihood function
Resumo:
Within the development of motor vehicles, crash safety (e.g. occupant protection, pedestrian protection, low speed damageability), is one of the most important attributes. In order to be able to fulfill the increased requirements in the framework of shorter cycle times and rising pressure to reduce costs, car manufacturers keep intensifying the use of virtual development tools such as those in the domain of Computer Aided Engineering (CAE). For crash simulations, the explicit finite element method (FEM) is applied. The accuracy of the simulation process is highly dependent on the accuracy of the simulation model, including the midplane mesh. One of the roughest approximations typically made is the actual part thickness which, in reality, can vary locally. However, almost always a constant thickness value is defined throughout the entire part due to complexity reasons. On the other hand, for precise fracture analysis within FEM, the correct thickness consideration is one key enabler. Thus, availability of per element thickness information, which does not exist explicitly in the FEM model, can significantly contribute to an improved crash simulation quality, especially regarding fracture prediction. Even though the thickness is not explicitly available from the FEM model, it can be inferred from the original CAD geometric model through geometric calculations. This paper proposes and compares two thickness estimation algorithms based on ray tracing and nearest neighbour 3D range searches. A systematic quantitative analysis of the accuracy of both algorithms is presented, as well as a thorough identification of particular geometric arrangements under which their accuracy can be compared. These results enable the identification of each technique’s weaknesses and hint towards a new, integrated, approach to the problem that linearly combines the estimates produced by each algorithm.
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Poly(vinylidene fluoride)/Pb(Zr0.53Ti0.47)O3,([PVDF]1−x/[PZT]x) composites of volume fractions x and (0–3) type connectivity were prepared in the form of thin films. PZT powders with average grain sizes of 0.2, 0.84, and 2.35 μm in different volume fraction of PZT up to 40 % were mixed with the polymeric matrix. The influence of the inorganic particle size and its content on the thermal degradation properties of the composites was then investigated by means of thermo-gravimetric analysis. It is observed that filler size affects more than filler concentration the degradation temperature and activation energy of the polymer. In the same way and due to their larger specific area, smaller particles leave larger solid residuals after the polymer degradation. The polymer degradation mechanism is not significantly modified by the presence of the inorganic fillers. On the other hand, an inhibition effect occurs due to the presence of the fillers, affecting particularly the activation energy of the process.
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A nomeação de Guimarães como Capital Europeia da Cultura (CEC) em 2012, para além de suscitar o natural orgulho e reforçar a auto-estima dos residentes, veio colocar na ordem do dia a necessidade de medir os efeitos que a concretização deste mega-evento pode provocar na cidade e no resto do município. A discussão dos benefícios e dos custos e um alargado envolvimento da comunidade tende a permitir encontrar formas de reduzir os impactos negativos e aumentar os impactos positivos. Para isto, importa realizar debates e promover a participação e envolvimento da comunidade. Esta comunicação analisa o envolvimento da população e das associações locais na Capital Europeia da Cultura 2012 através da cobertura feita pela imprensa local à preparação do evento. A análise de conteúdo às notícias publicadas abrangeu o período que medeia entre Janeiro e Agosto de 2011 e respeitou a dois semanários locais. Com base na análise efectuada, pode concluir-se que tem existido uma forte reacção negativa por parte da população e das associações locais à entidade organizadora da CEC 2012, que colocam em questão o envolvimento e participação prevista dos vimaranenses no evento. Resta saber se a nova gestão, nomeada em Agosto de 2011, será capaz de recuperar o entusiasmo e apoio da população vimaranense ao projecto a tempo de se constituir como um factor de sucesso deste mega-evento.
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In this paper, we present a method for estimating local thickness distribution in nite element models, applied to injection molded and cast engineering parts. This method features considerable improved performance compared to two previously proposed approaches, and has been validated against thickness measured by di erent human operators. We also demonstrate that the use of this method for assigning a distribution of local thickness in FEM crash simulations results in a much more accurate prediction of the real part performance, thus increasing the bene ts of computer simulations in engineering design by enabling zero-prototyping and thus reducing product development costs. The simulation results have been compared to experimental tests, evidencing the advantage of the proposed method. Thus, the proposed approach to consider local thickness distribution in FEM crash simulations has high potential on the product development process of complex and highly demanding injection molded and casted parts and is currently being used by Ford Motor Company.
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This paper seeks to investigate the use of performance information by politicians and whether the institutional reforms on performance management (PM) have been operationalized by local politicians. Differences on the policy field and the organizational context have been analyzed. Our goal is contribute to knowledge on PM in the political sphere and understand the different responses of politicians to government change initiatives (mainly coercive pressures). Our findings show that local politicians support the notion that greater attention should be devoted to the use of performance information on the evaluation process. Nevertheless they are very skeptic in relation to effective execution of government reforms. There is an internal culture where agencies are embedded, strongly influenced by the high degree of politicisation among senior managers, that lead politicians to be more concerned about personal opinions and informal performance information rather than to use more sophisticated information (output and outcome measures). The institutional approach helps us to identify political responses to institutional pressures and understand the reasons for a reduced use in the Portuguese context.
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Purpose/objectives: This paper seeks to investigate whether performance management (PM) framework adopted in Portuguese local government (PLG) fit the Otley’s PM framework (1999). In particularly, the research questions are (1) whether PM framework adopted in PLG (SIADAP) fit the Otley´s framework, and (2) how local politicians (aldermen) see the operation of performance management systems (PMS) in PLG (focusing on the goal-setting process and incentive and reward structures). Theoretical positioning/contributions: With this paper we intend to contribute to literature on how the Otley’s PM framework can guide empirical research about the operation of PMS. In particular, the paper contributes to understand the fit between PMS implemented in PLG and the Otley´s PM framework. The analysis of this fit can be a good contribution to understand if PMS are used in PLG as a management tool or as a strategic response to external pressures (based on interviews conducted to aldermen). We believe that the Otley’s PM framework, as well as the extended PM framework presented by Ferreira and Otley (2009), can provide a useful research tool to understand the operation of PMS in PLG. Research method: The first research question is the central issue in this paper and is analyzed based on the main reforms introduced by Portuguese government on PM of public organizations (like municipalities). On the other hand, interviews conducted on three larger Portuguese municipalities (Oporto, Braga, and Matosinhos) show how aldermen see the operation of PMS in PLG, highlighting the goals setting process with targets associated and the existing of incentive and reward structures linked with performance. Findings: Generally we find that formal and regulated PM frameworks in PLG fit the main issues of the Otley’s PM framework. However, regarding the aldermen perceptions about PMS in practice we find a gap between theory and practice, especially regarding difficulties associated with the lack of a culture of goals and targets setting and the lack of incentive and reward structures linked with performance.
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This paper studies the use of results oriented performance information (outputs and outcomes) by local elected politicians (aldermen) in top managers’ performance evaluation. The main goal is to understand the top managers’ performance evaluation process conducted by Portuguese aldermen and to identify the dominant evaluation style. In line with Bogt (2001), an exploratory field research was developed in three large municipalities: Porto, Braga and Matosinhos. We intend to answer the following research questions: to what extent are local politicians (aldermen) 1 using results information (about outputs and outcomes) to evaluate top managers’ performance? Do aldermen give any importance to quantitative output information and report them on current planning and control documents? Will the output performance information be used on performance evaluation in a different way concerning policy field (task orientation)? Based on the Hopwood evaluation styles (adapted from the private to the public sector by Bogt, 2001), we have found that the performance evaluation process of top managers is more featured by the ‘operations-conscious styles’ (or ‘implicit style’). Portuguese aldermen recognize the importance to quantify outputs and outcomes, but these days they focus on the information about activities and the realized operations when they evaluate performance. We haven´t found significant differences between different tasks (some exceptions for culture and environment areas). However, the municipality of Matosinhos paid more attention on quantitative performance information. This finding is reinforced by the quality of quantitative data on outputs reported on its management report. Generally speaking, aldermen are aware that more attention should be paid to quantitative information about results and performance, taking into account recent reforms introduced in Portuguese municipalities (PLG) on this field, but the ‘implicit’ style is dominant.
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In daily cardiology practice, assessment of left ventricular (LV) global function using non-invasive imaging remains central for the diagnosis and follow-up of patients with cardiovascular diseases. Despite the different methodologies currently accessible for LV segmentation in cardiac magnetic resonance (CMR) images, a fast and complete LV delineation is still limitedly available for routine use. In this study, a localized anatomically constrained affine optical flow method is proposed for fast and automatic LV tracking throughout the full cardiac cycle in short-axis CMR images. Starting from an automatically delineated LV in the end-diastolic frame, the endocardial and epicardial boundaries are propagated by estimating the motion between adjacent cardiac phases using optical flow. In order to reduce the computational burden, the motion is only estimated in an anatomical region of interest around the tracked boundaries and subsequently integrated into a local affine motion model. Such localized estimation enables to capture complex motion patterns, while still being spatially consistent. The method was validated on 45 CMR datasets taken from the 2009 MICCAI LV segmentation challenge. The proposed approach proved to be robust and efficient, with an average distance error of 2.1 mm and a correlation with reference ejection fraction of 0.98 (1.9 ± 4.5%). Moreover, it showed to be fast, taking 5 seconds for the tracking of a full 4D dataset (30 ms per image). Overall, a novel fast, robust and accurate LV tracking methodology was proposed, enabling accurate assessment of relevant global function cardiac indices, such as volumes and ejection fraction.
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Esta dissertação pretende estudar e demonstrar a importância da reorganização territorial ao nível do poder local, analisando em particular a fusão dos municípios de Aveiro e de Ílhavo. O principal objectivo deste trabalho reside em medir as implicações da reorganização territorial por via da fusão de municípios, o que é conseguido através do estudo da evolução histórica das várias reformas administrativas ocorridas em Portugal, com especial ênfase o século XIX devido ao seu enorme ímpeto reformista, bem como da análise de um caso muito específico de dois municípios vizinhos, que partilhando uma mesma realidade espacial e natural (Ria de Aveiro), já foram, em determinada época, um só município. Procurar-se-ão aferir quais os aspectos determinantes na tomada de decisão relativamente a esta temática, bem como avaliar os principais obstáculos e benefícios da sua concretização.
Options listing and the volatility of the underling asset: a study on the derivative market function
Resumo:
There are basic misunderstandings on derivative markets. Some professionals believe that they are a kind of casinos and have no utility for the investors. This work looks at the effects of options introduction in the Brazilian market, seeking for another benefit for this introduction: changes in the stocks risk leveI. Our results are the same found in the US and other markets: the options introduction reduces the stocks volatility. We also found that there is a slight indication that the volatility becames more stochastic with this alternative.
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Enormous change and innovation in governmental practices are occurring throughout the world. Local governance, in particular, has become a concern in many countries. Processes such as redemocratization and decentralization and imperatives of international lending agencies have focused attention on developing good governance practices. Improvement in local government remains a high priority in most countries, but unless the relationship between citizens and government is more fully developed the actions of local government will not necessarily lead to improvement in the conditions of people's lives. This paper will explore the concept of governance and propose an analytical framework for the study of local governance in an international context. The article concludes with recommendations on strategies to improve governance systems and government performance.
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The Fundação Getulio Vargas, São Paulo, Public Management and Citizenship Program was set up in 1996 with Ford Foundation support to identify and disseminate Brazilian subnational government initiatives in service provision that have a direct effect on citizenship. Already, the program has 2,500 different experiences in its data bank, the results of four annual cycles. The article draws some initial conclusions about the possibilities of a rights-based approach to public management and about the engagement of other agencies and civil society organizations.