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Number of results: 29
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Abstract

The fixation of CO2 in the form of inorganic carbonates, also known as mineral carbonation, is an interesting option for the removal of carbon dioxide from various gas streams. The captured CO2 is reacted with metal-oxide bearing materials, usually naturally occurring minerals. The alkaline industrial waste, such as fly ash can also be considered as a source of calcium or magnesium. In the present study the solubility of fly ash from conventional pulverised hard coal fired boilers, with and without desulphurisation products, and fly ash from lignite fluidised bed combustion, generated by Polish power stations was analysed. The principal objective was to assess the potential of fly ash used as a reactant in the process of mineral carbonation. Experiments were done in a 1 dm3 reactor equipped with a heating jacket and a stirrer. The rate of dissolution in water and in acid solutions was measured at various temperatures (20 - 80ºC), waste-to-solvent ratios (1:100 - 1:4) and stirrer speeds (300 - 1100 min-1). Results clearly show that fluidised lignite fly ash has the highest potential for carbonation due to its high content of free CaO and fast kinetics of dissolution, and can be employed in mineral carbonation of CO2.
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Abstract

The main goal of this paper is to propose the probabilistic description of cyclical (business) fluctuations. We generalize a fixed deterministic cycle model by incorporating the time-varying amplitude. More specifically, we assume that the mean function of cyclical fluctuations depends on unknown frequencies (related to the lengths of the cyclical fluctuations) in a similar way to the almost periodic mean function in a fixed deterministic cycle, while the assumption concerning constant amplitude is relaxed. We assume that the amplitude associated with a given frequency is time-varying and is a spline function. Finally, using a Bayesian approach and under standard prior assumptions, we obtain the explicit marginal posterior distribution for the vector of frequency parameters. In our empirical analysis, we consider the monthly industrial production in most European countries. Based on the highest marginal data density value, we choose the best model to describe the considered growth cycle. In most cases, data support the model with a time-varying amplitude. In addition, the expectation of the posterior distribution of the deterministic cycle for the considered growth cycles has similar dynamics to cycles extracted by standard bandpass filtration methods.
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Abstract

The subject of this article are the Egyptian inspirations in the graphic works of Ewa Siedlecka-Kotula, an artist living and working in Kraków in the second half of the 19th century. During the period from May 1948 until June 1949 she resided in Cairo, a productive period which came to fruition in the form of a special cycle of linocuts, executed in 1969 and based on earlier sketches. The series comprises of the following works: “Kobiety/Women”, “Woda/Water”, “Ryż/Rice”, “Tkacze/Weavers”, “Pasterka/ Female shepherd”, and “Barany/Rams”, depicting contemporary Egyptians and their typical, everyday tasks. During her stay in Egypt the artist also designed the exhibition graphics for the 16th Agricultural and Industrial Exhibition in Cairo. Her works were put on display at an individual exhibition (December 1948). She also participated in the exhibitions entitled “Le salon des femmes-artistes” in Cairo Women’s Club (March 1949) and “France-Égypte” in the Museum of Modern Art in Cairo (May 1949). Ewa Siedlecka-Kotula’s works met with much interest at that time. Unfortunately, references to antiquity are very scarce in her art, and include only a watercolour showing an Egyptian peasant by a shaduf (fig. 1), and a drawing of a female offering-bringer figurine from the tomb of Nakhti, overseer of the seal, in Asyut (early 12th dynasty, around 1900 BC). The latter drawing was perhaps made in the Egyptian Museum in Cairo, and most likely represents a statuette whose current fate remains unknown, which would make this drawing an exceptional record.
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