A eletricidade e o eletromagnetismo estão presentes no nosso dia-a[1]dia na quase totalidade dos ... more A eletricidade e o eletromagnetismo estão presentes no nosso dia-a[1]dia na quase totalidade dos equipamentos que usamos, quer no trabalho quer em períodos de lazer, desde a máquina mais sofisticada ao mais simples eletrodoméstico. Associado à utilização está o consumo de energia elétrica que pode ser reduzido com uma eficiente escolha e correta utilização. Considerando a atual situação económica mundial, em especial a Portuguesa, e o aumento dos custos de energia elétrica devido à variação da cotação do preço do petróleo e do carvão, todo o contributo para a diminuição do consumo será pertinente, permitindo a diminuição, mesmo que pequena, da fatura de energia das famílias e aumentando o rendimento disponível. Este trabalho tem por objetivo sensibilizar para a necessidade de redução do consumo de energia. Será analisada a eficiência energética dos equipamentos elétricos de uso corrente, sua implicação nos custos energéticos a incluir na fatura doméstica e redução de consumo de ener...
The outburst of the COVID-19 pandemic and its rapid spread throughout the world in 2020 shed a ne... more The outburst of the COVID-19 pandemic and its rapid spread throughout the world in 2020 shed a new light on mathematic models describing the nature of epidemics. However, as the pandemic shocked economies to a much greater extent than earlier epidemics, the recovery potential of economies was emphasized and its inclusion in epidemic models is becoming more important. The present paper deals with the issues of modeling the recovery of economic systems that have undergone severe medical shocks, such as COVID-19. The proposed mathematical model considers the close relationship between the dynamics of pandemics and economic development. This distinguishes it from purely “medical” models, which are used exclusively to study the dynamics of the spread of the COVID-19 pandemic. Unlike standard SIR models, the present approach involves the introduction of the “vaccine” equation to the SIR model and introduces correction components that include the possibility of re-infection and other nuanc...
In the period from the 1920s to 1930s the theory of economic cycles underwent dramatic<br> ... more In the period from the 1920s to 1930s the theory of economic cycles underwent dramatic<br> changes. Due to the research of such famous economists as Nikolay Kondratieff, Joseph<br> Kitchin, Wesley Mitchell, Simon Kuznets, and Joseph Schumpeter the idea of a whole system<br> of economic cycles (with characteristic periods between two and sixty years) was developed.<br> The idea of a system of intertwined economic cycles is nowadays paramount to<br> the school of evolutionary economics and its development promises rather interesting future<br> outcomes. That is why this issue of our 'Kondratieff Waves' Yearbook is devoted to<br> the interconnections between various economic cycles.<br> As to the subtitle of this volume, one should note that many of the contributors refer to the<br> system of cycles and the fact that real economic cycles make up a system, whereas among<br> different types of cycles, the Juglar, Kuznets...
Digital technologies, robotic automation and artificial intelligence are becoming the main driver... more Digital technologies, robotic automation and artificial intelligence are becoming the main drivers of technological and economic development. In this regard, it is quite natural that the demand for justification of such threats for the employment market appears, and also the question arises whether it is possible to foresee and analyze the level of inequality and distribution of income in the society where the proportion of artificial intellectual systems in creating new costs will be exceptionally large.
In this work, commercial alumina fine powders were used as raw materials, namely two tabular alum... more In this work, commercial alumina fine powders were used as raw materials, namely two tabular alumina fractions (–500 mesh and –230 mesh) and a reactive alumina. Statistical modelling and the Response Surface Methodology (Statistica, Mixtures Designs and Triangular Surfaces module) were applied to three-component mixtures and used to calculate the various property-composition surfaces. To that aim, the various mixtures were prepared, cast, dried, fired and characterised. The particle size distribution modulus, q, was determined for all mixtures using the software LISA. The various response surfaces were then combined, so that the water content in the mixture could be minimised and the matrix flowability maximised. The properties of the resulting test-bricks (linear shrinkage, mechanical strength, apparent density and porosity) were also modelled and response surfaces were obtained. Combined results enabled the definition of an optimised particle size composition range, which guarante...
A eletricidade e o eletromagnetismo estão presentes no nosso dia-a[1]dia na quase totalidade dos ... more A eletricidade e o eletromagnetismo estão presentes no nosso dia-a[1]dia na quase totalidade dos equipamentos que usamos, quer no trabalho quer em períodos de lazer, desde a máquina mais sofisticada ao mais simples eletrodoméstico. Associado à utilização está o consumo de energia elétrica que pode ser reduzido com uma eficiente escolha e correta utilização. Considerando a atual situação económica mundial, em especial a Portuguesa, e o aumento dos custos de energia elétrica devido à variação da cotação do preço do petróleo e do carvão, todo o contributo para a diminuição do consumo será pertinente, permitindo a diminuição, mesmo que pequena, da fatura de energia das famílias e aumentando o rendimento disponível. Este trabalho tem por objetivo sensibilizar para a necessidade de redução do consumo de energia. Será analisada a eficiência energética dos equipamentos elétricos de uso corrente, sua implicação nos custos energéticos a incluir na fatura doméstica e redução de consumo de ener...
The outburst of the COVID-19 pandemic and its rapid spread throughout the world in 2020 shed a ne... more The outburst of the COVID-19 pandemic and its rapid spread throughout the world in 2020 shed a new light on mathematic models describing the nature of epidemics. However, as the pandemic shocked economies to a much greater extent than earlier epidemics, the recovery potential of economies was emphasized and its inclusion in epidemic models is becoming more important. The present paper deals with the issues of modeling the recovery of economic systems that have undergone severe medical shocks, such as COVID-19. The proposed mathematical model considers the close relationship between the dynamics of pandemics and economic development. This distinguishes it from purely “medical” models, which are used exclusively to study the dynamics of the spread of the COVID-19 pandemic. Unlike standard SIR models, the present approach involves the introduction of the “vaccine” equation to the SIR model and introduces correction components that include the possibility of re-infection and other nuanc...
In the period from the 1920s to 1930s the theory of economic cycles underwent dramatic<br> ... more In the period from the 1920s to 1930s the theory of economic cycles underwent dramatic<br> changes. Due to the research of such famous economists as Nikolay Kondratieff, Joseph<br> Kitchin, Wesley Mitchell, Simon Kuznets, and Joseph Schumpeter the idea of a whole system<br> of economic cycles (with characteristic periods between two and sixty years) was developed.<br> The idea of a system of intertwined economic cycles is nowadays paramount to<br> the school of evolutionary economics and its development promises rather interesting future<br> outcomes. That is why this issue of our 'Kondratieff Waves' Yearbook is devoted to<br> the interconnections between various economic cycles.<br> As to the subtitle of this volume, one should note that many of the contributors refer to the<br> system of cycles and the fact that real economic cycles make up a system, whereas among<br> different types of cycles, the Juglar, Kuznets...
Digital technologies, robotic automation and artificial intelligence are becoming the main driver... more Digital technologies, robotic automation and artificial intelligence are becoming the main drivers of technological and economic development. In this regard, it is quite natural that the demand for justification of such threats for the employment market appears, and also the question arises whether it is possible to foresee and analyze the level of inequality and distribution of income in the society where the proportion of artificial intellectual systems in creating new costs will be exceptionally large.
In this work, commercial alumina fine powders were used as raw materials, namely two tabular alum... more In this work, commercial alumina fine powders were used as raw materials, namely two tabular alumina fractions (–500 mesh and –230 mesh) and a reactive alumina. Statistical modelling and the Response Surface Methodology (Statistica, Mixtures Designs and Triangular Surfaces module) were applied to three-component mixtures and used to calculate the various property-composition surfaces. To that aim, the various mixtures were prepared, cast, dried, fired and characterised. The particle size distribution modulus, q, was determined for all mixtures using the software LISA. The various response surfaces were then combined, so that the water content in the mixture could be minimised and the matrix flowability maximised. The properties of the resulting test-bricks (linear shrinkage, mechanical strength, apparent density and porosity) were also modelled and response surfaces were obtained. Combined results enabled the definition of an optimised particle size composition range, which guarante...
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