An Extension of Dematerialization Theory: Incorporation of Technical Performance Increases and the Rebound Effect

Dematerialization is the reduction in the quantity of materials needed to produce something useful over time. Dematerialization fundamentally derives from ongoing increases in technical performance but it can be counteracted by demand rebound -increases in usage because of increased value (or decreased cost) that also results from increasing technical performance. A major question then is to what extent technological performance improvement can offset and is offsetting continuously increasing economic consumption. This paper contributes to answering this question by offering some simple quantitative extensions to the theory of dematerialization. An inequality criterion for dematerialization is developed that includes technical performance changes over time and demand rebound effects: the inequality highlights the importance of demand elasticity and the annual technical performance improvement rate. The paper then empirically examines the materials consumption trends as well as cost trends for a large set of materials and a few modern artifacts over the past decades. In all 57 cases examined, the particular combinations of demand elasticity and technical capability rate improvement for each case are consistent with continuation of materialization. Overall, the theory extension and empirical examination indicate that dematerialization and sustainability are significant challenges not easily met by undirected technological change

Kondratieff Waves: Juglar – Kuznets – Kondratieff; Yearbook

In the period from the 1920s to 1930s the theory of economic cycles underwent dramatic changes. Due to the research of such famous economists as Nikolay Kondratieff, Joseph Kitchin, Wesley Mitchell, Simon Kuznets, and Joseph Schumpeter the idea of a whole system of economic cycles (with characteristic periods between two and sixty years) was developed. The idea of a system of intertwined economic cycles is nowadays paramount to the school of evolutionary economics and its development promises rather interesting future outcomes. That is why this issue of our ‘Kondratieff Waves’ Yearbook is devoted to the interconnections between various economic cycles. As to the subtitle of this volume, one should note that many of the contributors refer to the system of cycles and the fact that real economic cycles make up a system, whereas among different types of cycles, the Juglar, Kuznets, and Kondratieff cycles are the most important ones for the present-day economic dynamics. Although Kondratieff himself considered long waves as above all an economic phenomenon, the theory of the long waves became, however, very actively developed in connection with their political and geopolitical aspects. In this Yearbook, the political aspect of Kondratieff waves is the subject of several articles in the second section. The last section of this Yearbook is devoted to the heritage of Kondratieff and other prominent economists. The year 2015 marks the 150th anniversary of the outstanding Russian economist, one of the most prominent researchers of medium-term economic cycles, Mikhail Tugan-Baranovsky, and the volume is concluded with Kondratieff's article about him. Concerning 2015, we should mention another anniversary, namely, 30 years since the death of Simon Kuznets (1901–1985). This edition will be useful for economists, social scientists, as well as for a wide range of those interested in the problems of the past, present, and future of global economy and globalization

Energy scenarios: Toward a new energy paradigm

Primary energy sources exhibited regular long-term logistic substitution trends from the mid-19th century through the third quarter of the 20th century. This analysis, based on an extension of the Fisher–Pry substitution model, accounted for the observed historical shifts of primary energy use from sources of wood, coal, oil, natural gas, and nuclear. In the mid1980s the substitution dynamics was replaced by a relatively constant contribution from oil, natural gas, coal, nuclear power, and hydropower. However, a major factor in energy use dynamics in this recent period was substitution of conservation and efficiency for actual fuel use. The energy efficiency is measured as the ratio of economic activity to the rate of energy use (energy intensity). To incorporate these data into the logistic analysis, a method for estimating the fraction of energy saved by the increased efficiency was used. With this interpretation, energy efficiency fits within the substitution model. Furthermore, to identify indications of future energy scenarios, as well as to test the logistic substitution analysis, another statistical approach using ternary diagrams was developed. The consistent results from both logistic substitution and statistical analysis are compared with recent energy projections, trends in decarbonization, Kondratieff waves, and other efficiency measures. While the specific future mix of renewables and nuclear energy sources is uncertain, the more general logistic dynamics pattern of the energy system seems to be continuing as it has for about 150 years now.Authors Tessaleno Devezas, Joao C.O. Matias and Abılio M.P. Silva wish to thank the Portuguese Fundacao de Ciencia e Tecnologia (FCT), which supported (through the Unity of R&D no. 151) the present investigation.info:eu-repo/semantics/publishedVersio

Thermomechanical evaluation of self-flowing refractory castables with and without the addition of aluminate cement

Much has been discussed about the advantages regarding the thermomechanical performance of self-flow refractory castables (SFRC), with very little or no addition of calcium aluminate cement (CAC) when compared to conventional composites with cement. Previous works demonstrated that a 100% alumina SFRC with optimized particle size distribution simultaneously results in high-flowability fresh paste and high mechanical strength. In this work, the thermomechanical behaviour of zero-cement ceramic matrix is compared to that of the equivalent composite with 1% CAC content. The results show that the differences in performance can be related to differences in hydration mechanisms, namely the formation sequence of calcium aluminate hydrates, which results in increased open porosity. With lower dried strength, the all-alumina castable presents lower porosity, higher mechanical strength and uncompromised thermal shock resistance, being a valuable option when fast drying or rough green handling can be avoided.info:eu-repo/semantics/publishedVersio

Designing particle sizing and packing for flowability and sintered mechanical strength

In this work, alumina powders in five different commercially available size ranges were used to prepare various refractory castable mixtures, defined using the statistical design of mixture experiments (STATISTICA, StatSoft Inc.) and the EMMA 3.3 software (Elkem Materials). Those mixtures were characterized for packing density, Andreasen particle size distribution modulus (q), flowability and after sintering properties, in order to investigate the relationships between these variables. The optimization of matrix and aggregate sizes and matrix-aggregate proportion, subjected to different property requirements, brought to light the relationships between q, specific surface area (SSA) and maximum paste thickness (MPT). Those relationships were investigated for three fundamental processing steps, namely, dry powders, fresh paste and consolidated dried and sintered bodies. The optimized all-alumina castable was found to require 47.5wt.% of a fine size matrix with high flowability, which provides the necessary flow bed for 52.5wt.% of coarse aggregates, resulting in a gap-sized particle size distribution, and presented a fresh paste flowability index above 130% with minimum added water (28mg/m2) and sintered modulus of rupture above 50MPa.info:eu-repo/semantics/publishedVersio

Aplicação de métodos estatísticos na otimização da densidade de empacotamento de distribuições de pós de alumina

Fatores como a distribuição granulométrica e a morfologia condicionam as propriedades físicas de sistemas particulados (e.g. misturas de pós, pastas, concretos refratários), entre as quais a densidade de empacotamento. Podem ser encontrados, na literatura, vários modelos para a otimização da distribuição de tamanhos de partículas que maximiza o empacotamento, todos desenvolvidos para sistemas de esferas perfeitas (e.g. Furnas, Andreasen, Alfred). Neste trabalho, pós de alumina comercial (reativa e tabular) foram separados em nove frações granulométricas e, recorrendo a dois procedimentos distintos, construíram-se seis sistemas ternários diferentes e complementares de tamanhos de partículas. Usando a metodologia das superfícies de resposta e técnicas de análise estatística afins (programa de cálculo Statistica) obteve-se, em ambos os casos, a distribuição granulométrica que maximiza a densidade de empacotamento. Por comparação com as distribuições granulométricas teóricas, ficou demonstrada a validade do modelo teórico de Alfred para esferas perfeitas. Os resultados obtidos demonstram, assim, que o efeito prejudicial da não esfericidade das partículas pode ser, na realidade, compensado pela otimização da distribuição granulométrica global.Particle size distribution and morphology are among the factors that affect the physical properties of particulate systems (e.g. powder mixtures, pastes, castable refractories). One such property is packing density. There are, in the literature, models that optimise particle size distributions for maximum packing density, all of them derived for spherical particles (e.g. Furnas, Andreasen, Alfred). In this work, commercial alumina powders (reactive and tabular) were divided into nine particle size classes. Following two different approaches, the latter were used to build six different ternary systems of complementary particle sizes. Using the response surface methodology and related statistical techniques (software Statistica), the particle size distribution that maximises the packing density was obtained in both cases and, by comparison with theoretical particle size distributions, the validity of Alfred’s theoretical model for perfect spheres was demonstrated. These results clearly show that the harmful effect of the nonspherical shape of real particles can, in fact, be compensated by the optimization of the overall particle size distribution.info:eu-repo/semantics/publishedVersio

Effect of particle size distribution and calcium aluminate cement on the rheological behaviour of all-alumina refractory castables

Previous works based on statistical design of experiments (DoE) defined a model all-alumina self-flow refractory castable (SFRC) with optimized particle size distribution for simultaneous high flowability index (FI) and superior post-sintering performance. This work compares the SFRC rheological behaviour and setting time with those of alternative all-alumina castables with different Andreasen aggregate particle size distribution modulus, and of the equivalent castables containing calcium aluminate cement. The model castable showed Bingham behaviour with low yield stress, viscosity and thixotropy, guaranteeing easier casting and less wear in the casting and/or projection equipment. However, as the coarse particle fraction increases, the castable flow tends to be non-linear and changes from Bingham to Herschel–Bulkley. The cement containing castables quickly loose flowability despite the applied shear. This work confirmed previous conclusions based on FI measurements and demonstrates the adequacy of the use of FI values in the calculation of FI response surface by DoE.info:eu-repo/semantics/publishedVersio

Digital economy and the models of income distribution in the societya

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