On an extreme value version of the Birnbaum-Saunders distribution

The Birnbaum-Saunders model is a life distribution originated from a problem of material fatigue that has been largely studied and applied in recent decades. A random variable following the Birnbaum-Saunders distribution can be stochastically represented by another random variable used as basis. Then, the Birnbaum-Saunders model can be generalized by switching the distribution of the basis variable using diverse arguments allowing to construct more general classes of models. Extreme value distributions are useful to determinate the probability of events that are more extreme than any that have already been observed. In this paper, we propose, characterize, implement and apply an extreme value version of the Birnbaum-Saunders distribution.Fundação para a Ciência e a Tecnologia (FCT) - Pluriannual Funding Program, PTDC/FEDER, PEst-OE/MAT/UI0006/2011, FCT/OE, POCI 2010FONDECYT (Fondo Nacional de Desarrollo Cient co y Tecnol ogico - Chile

The extreme value Birnbaum-Saunders model in athletics

The Birnbaum-Saunders (BS) model is a life distribution that has recently been largely studied and applied. A random variable following the BS distribution can be defined through a simple transformation of a standard normal. The BS model can thus be generalized by switching the standard normal distribution of the basis random variable, allowing the construction of more general classes of models. Among those models, we mention the extreme value Birnbaum-Saunders (EVBS) models, recently introduced in the literature, and based on results from extreme value theory. A real application to athletics data will be used to illustrate the methodology and to provide the way this model and related models can link with traditional extreme value analysis methods.Este trabalho é financiado por Fundos FEDER através do Programa Operacional Factores de Competitividade - COMPETE e por Fundos Nacionais através da FCT - Fundação para a Ciência e a Tecnologia no âmbito do projecto PEst-C/MAT/UI0013/2011.Este trabalho é financiado por Fundos FEDER através do Programa Operacional Factores de Competitividade - COMPETE e por Fundos Nacionais através da FCT - Fundação para a Ciência e a Tecnologia no âmbito do projecto PEst-C/MAT/UI0013/2011

The extreme value Birnbaum-Saunders model, its moments and an application in biometry

The Birnbaum-Saunders (BS) model is a life distribution that has been largely studied and applied. Recently, a new version of the BS distribution based on extreme value theory has been introduced, which is named extreme value Birnbaum-Saunders (EVBS) distribution. In this article, we provide some further details on the EVBS models that can be useful as a supplement to the already existing results. We use these models to analyze real survival time data of patients treated with alkylating agents for multiple myeloma. This analysis allow us to show the adequacy of these new statistical distributions and identify them as models useful for medical practitioners in order to obtain a prediction of the survival times of these patients and evaluate changes in the dose of their treatment.Fundação para a Ciência e a Tecnologia (FCT) - Pluriannual Funding Program, PTDC/FEDER, PEst-OE/MAT/UI0006/2011, FCT/OE, POCI 201

Interligação de conversores forward para processamento de energia proveniente de fontes de baixa tensão e alta corrente

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2017.Neste trabalho apresenta-se de um conversor cc-cc capaz de lidar com fontes de baixa tensão e elevada corrente de entrada. A topologia proposta é baseada em uma configuração de conversores Forward com entradas conectadas em paralelo e saídas conectadas em série. A referida configuração permite o compartilhamento natural da corrente de entrada entre os módulos associados e resulta e em elevado ganho estático. Mediante a aplicação de modulação phase-shift ao acionamento dos interruptores, há a possibilidade de redução do volume dos componentes que compõem o único filtro de saída da estrutura. O estudo realizado neste trabalho inclui: análise das interligações entre conversores Forward, análise das etapas de operação, formas de onda teóricas, a modelagem do conversor orientada ao controle e proposta de uma estratégia de controle. A partir de um protótipo de 1 kW e 85% de eficiência são extraídos resultados experimentais que validam a teoria e as equações derivadas ao longo do texto.Abstract : This work presents a DC-DC converter capable of dealing with low voltage sources and high input current. The proposed topology is based on a configuration of Forward converters with parallel connected inputs and serially connected outputs. Said configuration allows a natural sharing of the input current between the associated modules and results in high static gain to the converter. By applying a phase-shift modulation to drive the switches, there is the possibility of reducing the volume of the components that make up the output filters of the structure. The study carried out in this work includes: analysis of Forward converter interconnections, analysis of the operation stages, theoretical waveforms, converter modeling oriented to control and proposal of a control strategy. From a prototype of 1 kW and 85% efficiency are extracted experimental results that validate the theory and derived equations throughout the text

Interligação de conversores forward para processamento de energia proveniente de fontes de baixa tensão e alta corrente

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2017.Neste trabalho apresenta-se de um conversor cc-cc capaz de lidar com fontes de baixa tensão e elevada corrente de entrada. A topologia proposta é baseada em uma configuração de conversores Forward com entradas conectadas em paralelo e saídas conectadas em série. A referida configuração permite o compartilhamento natural da corrente de entrada entre os módulos associados e resulta e em elevado ganho estático. Mediante a aplicação de modulação phase-shift ao acionamento dos interruptores, há a possibilidade de redução do volume dos componentes que compõem o único filtro de saída da estrutura. O estudo realizado neste trabalho inclui: análise das interligações entre conversores Forward, análise das etapas de operação, formas de onda teóricas, a modelagem do conversor orientada ao controle e proposta de uma estratégia de controle. A partir de um protótipo de 1 kW e 85% de eficiência são extraídos resultados experimentais que validam a teoria e as equações derivadas ao longo do texto.Abstract : This work presents a DC-DC converter capable of dealing with low voltage sources and high input current. The proposed topology is based on a configuration of Forward converters with parallel connected inputs and serially connected outputs. Said configuration allows a natural sharing of the input current between the associated modules and results in high static gain to the converter. By applying a phase-shift modulation to drive the switches, there is the possibility of reducing the volume of the components that make up the output filters of the structure. The study carried out in this work includes: analysis of Forward converter interconnections, analysis of the operation stages, theoretical waveforms, converter modeling oriented to control and proposal of a control strategy. From a prototype of 1 kW and 85% efficiency are extracted experimental results that validate the theory and derived equations throughout the text

Multiple-Criteria Decision Analysis and characterisation of phase change materials for waste heat recovery at high temperature for sustainable energy-intensive industry

A latent heat storage system based on Phase Change Materials (PCMs) is proposed to increase the energy and environmental efficiency by recovering and storing waste heat from combustion gases or other surplus sources at in the energy-intensive industries (EII), currently unused. The final configuration design is specifically adapted to the plant operational requirements, by means of a methodology combining the search of the best conceptual design and a proper selection of core PCMs. To that end, a selection of suitable PCM is carried out by using characterisation techniques and thermal stability testing. Furthermore, relevant key factors are weighted by an in-house Multiple-Criteria Decision Analysis (MCDA) to define the most promising design options to be implemented in two plants belonging to the EII sector. For the ceramic sector, the design resulted in a shell-and-tube system with 1188 kg of a PCM melting at 885 °C and encapsulated in double concentric tubes, involving a storage capacity of 227 MJ. Similarly, 1606 kg of PCM, whose phase-change temperature is 509 °C, is selected for the steel sector providing a PCM-TES system capable to store 420 MJ

Do Fire Regime Attributes Affect Soil Biochemical Properties in the Same Way under Different Environmental Conditions?

Global change is altering fire frequency and severity in many regions across the world. In this work, we studied the impact of different frequency and severity regimes on the soil biochemical properties in burned areas with different environmental conditions. We selected three sites dominated by pine ecosystems along a Mediterranean-Transition-Oceanic climatic gradient, where we determined the fire frequency, and severity of the last wildfire. Four years after the last wildfire, we established 184 4 m2 plots. In each plot, we collected a composed soil sample from a 3 cm depth, and measured several ecological variables potentially affected by the fire frequency and severity (cover of bare soil, cover of fine and coarse plant debris, cover of vegetation, and vegetation height). From each soil sample, we analyzed the enzymatic activities corresponding to the biogeochemical cycles of carbon, nitrogen, and phosphorus (β-glucosidase, urease, and acid-phosphatase, respectively), and the microbial biomass carbon. The results indicated that fire frequency only played a significant role in soil biochemical properties at the Mediterranean and Transition sites. Specifically, we found that increases in frequency contributed to increased urease and phosphatase activities (at the Transition site), as well as microbial biomass carbon (at the Mediterranean and Transition sites). In relation to burn severity, we found opposite patterns when comparing the Mediterranean and Oceanic sites. Specifically, increased severity significantly decreased β-glucosidase, urease, and microbial biomass carbon at the Mediterranean site, whereas at the Oceanic one, severity significantly increased them. Burn severity also decreased microbial biomass carbon at the Transition site. Our results also indicated that, overall, fire frequency determined the studied ecological variables at the Mediterranean and Transition sites, but clear indirect effects on biochemical properties due to changes in ecological variables were not found. This study adds to the knowledge on the impact of shifts in fire regimes on soils in the current context of changeThis study was financially supported by the Spanish Ministry of Economy and Competitiveness; the Spanish Ministry of Science, Innovation and Universities; and the European Regional Development Fund (ERDF), in the framework of the GESFIRE (AGL2013-48189-C2-1-R) and FIRESEVES (AGL2017-86075-C2-1-R) projects, and by the Regional Government of Castile and León in the framework of the FIRECYL (LE033U14) and SEFIRECYL (LE001P17) projectsS

The role of the agricultural sector in Ghanaian development: a multiregional SAM-based analysis

Ghana shows remarkable differences in employment and welfare between the southern and northern regions. The promotion of policy focus on the development of the northern regions requires the elaboration of specific databases describing the regional economies. Hence, this work outlines the construction of a Social Accounting Matrix (SAM) for Ghana for the year 2015 with a high disaggregation of sectors, household income groups and education levels across 10 administrative regions. Linear multisectoral models have been applied to this SAM to estimate socio-economic impacts of potential final demand policies down to a regional level in the Ghanaian economy. Further on, the structural path analysis is used to investigate the role played by different agriculture commodities in transmitting income to different types of households. The results allow for an identification of the most suitable sectors to be promoted due to their ability to generate the highest increases in output, employment and value added in the rest of the economy, as well as those with a significant impact on household income generation. As a result, the primary sector will play a key role in the economic and employment growth of the country. Notably, sorghum and millet, pulses, tobacco, cotton and fibres can be considered favourable crops for development in the Northern region

O verbo modal poder e a construção só pode em português : aspectos sintáticos e semânticos

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Instituto de Letras, Departamento de Linguística, Português e Línguas Clássicas, 2020.Neste trabalho, estudamos a construção “só pode” em português brasileiro, buscando entender qual o papel da palavra “só” nessa estrutura e como ela se relaciona com a quantificação existencial do verbo auxiliar modal “poder”. Inicialmente, tratamos da categoria linguística “modalidade”: definição, tipos de modalidade mais comuns, meios de expressão da modalidade em português e, por fim, o verbo “poder”. Em seguida apresentamos a fundamentação teórica do trabalho, que é a teoria quantificacional da modalidade proposta por Kratzer (2012) e descrita em detalhes em Bravo (2017). Depois, empreendemos um estudo mais aprofundado das propriedades da partícula “só”, no português do Brasil, pautando-nos no que apontam Gritti e Resenes (2008): “só” é um elemento focalizador, que exaure as alternativas que poderiam ser utilizadas pelo falante e pode implicar uma escala de importância, em determinados contextos. No que se refere à estrutura “só pode”, o que parece haver é uma influência desse papel restritivo de “só” quando combinado com o verbo auxiliar modal “poder”, quantificador existencial. Dessa combinação, resulta que a expressão “só pode” apresenta semelhanças com os verbos “ter que” e “dever”, auxiliares modais universais. A fim de entender o lugar de “só pode” nessa escala quantificacional, recorremos ao trabalho de Pires de Oliveira e Scarduelli (2008) e mostramos que “só pode” e os modais “deve” e “tem que” apresentam significados próximos, a depender da fonte de ordenação considerada. Com base na teoria Kratzeriana e na análise de dados, argumentamos que a construção “só pode” funciona como um verbo modal cuja quantificação é universal, devido à influência que a palavra “só” exerce sobre o modal “poder”.This paper studies the construction “só pode” (literally, “only can”) in Brazilian Portuguese, in order to understand the role of the word “só” in this structure and how it relates with the existencial quantification of the auxiliar modal verb “poder”. Beforehand, we approach the linguistic category “modality”: definition, common types of modalities, ways of expressing modality in Portuguese and, lastly, the verb “poder”. In sequency, we introduce the theorical bsis of this study, namely the quantificational theory of modality suggested by Kratzer (2012) and described in detail in Bravo (2017). Afterwards, we engage a deeper study of the proprieties of the particle “só”, in Brazilian Portuguese, based on Gritti and Resenes (2008): “só” is a focal element, which wears out the alternatives that could be used by the speaker and it can implicate a scale of importance, in some contexts. However, the structure “só pode” seems to have an influence of this restrictive power of “só” whenever combined with the auxiliar modal verb “poder”, an existential quantifier. The combination “só pode” shows similarities to the universal modal verbs “ter que” (literally, “have that”) and “dever” (“must”). To understand the place of “só pode” in the quantification scale of modals, we go back to Pires de Oliveira and Scarduelli’s (2008) work and show that “só pode” and modals “deve, “tem que”, present close meanings, relying on the ordering source considered. Based on Kratzerian’s theory and data analysis, we argued that the construction “só pode” works as a universal modal verb, due to the influence the word “só” has over the modal “poder”