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Abstract

The paper analyzed the natural gas sector in Ukraine for the period 2000 to 2018. This sector was affected by external factors, such as the crisis which began in late 2008/2009, as well as internal factors, including the situation in Ukraine after 2013 (the Annexation of Crimea). A comparative analysis was also conducted of the natural gas sector in European Union countries and Ukraine – compared the specificity of natural gas consumption in 2018. The analysis (I) examined the demand for natural gas in Ukraine between 2000 and 2018; (II) described changes in sources to cover Ukraine’s gas needs with a particular emphasis on its own production; (III) pointed to the fundamental changes that have occurred in the natural gas supply routes to the Ukrainian sector in recent years; (IV) stressed the growing role of own production in balancing Ukraine’s gas needs; (V) described the role of Ukraine as a transit country for Russian gas to be delivered to EU countries (in recent years, the volume of natural gas transmitted via the Ukrainian transmission system has been around 90 bcm annually); and (VI) looked at the structure of natural gas consumption in the Ukrainian gas sector and how it has changed in recent years. Unlike EU countries, the growing role of own production in balancing Ukraine’s natural gas needs was emphasized, which is consistent with the strategy of the Ukrainian government. Also, attention was drawn to the threats that may significantly reduce the role of Ukraine as an important transit country. The paper also puts forward the most important parameters concerning the underground natural gas storage facilities in Ukraine which is one of the largest in Europe.

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Authors and Affiliations

Adam Szurlej
Mariusz Łaciak
Oleksandr Boiko
Andrzej Olijnyk
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Abstract

Solar cell performance decreases with increasing temperature, heat can reduce output efficiency by 10–25%. The operating temperature plays a key role in the photovoltaic conversion process. Increase in electrical efficiency depends on cooling techniques, in particular photovoltaic modules installed in the high temperature regions. A cooling process using a single nozzle of photovoltaic panel operating under different configurations was simulated. The simulation contains two parts: the first is a thermodynamic investigation of fluid impingement upon the sensor front face. The second is a performance comparison between two types of glass cover. The major result that emerges from this simulation is the effect of a single nozzle arrangement to enhance the cooling process, under a low cadence of impinging droplets in the range 0.1–1.7 m/s.
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Bibliography

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Authors and Affiliations

Hocine Mzad
1
Abdessalam Otmani
1

  1. Mechanical Engineering Department, Badji Mokhtar University of Annaba, P.O. Box 12, DZ-23000, Algeria
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Abstract

The article presents new coins and die-chains of Bolesław the Brave’s coins. A mule of the PRINCES POLONIE type and an Otto-Adelheid imitation, kept in the State Historical Museum in Moscow, connected two previously known die-chains, enlarging the number of Bolesław the Brave’s coin types. New coins from the antiquarian market also expanded the DVX INCLITVS die chain. All these new coins and die chains show that despite the chaotic and incidental character of Bolesław the Brave’s coinage, in most cases the dies were produced in stylistically homogenous pairs, which were mixed afterwards during the minting process. Analysis of the quantity and chronology of Bolesław’s coins might also suggest that the heir to the throne, Mieszko II, was responsible for a relative ‘ordering’ of the oldest Polish coinage.

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Authors and Affiliations

Mateusz Bogucki
ORCID: ORCID
Jacek Magiera
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Abstract

The paper presents a heuristic approach to the problem of analog circuit diagnosis. Different optimization techniques in the field of test point selection are discussed. Two new algorithms: SALTO and COSMO have been introduced. Both searching procedures have been implemented in a form of the expert system in PROLOG language. The proposed methodologies have been exemplified on benchmark circuits. The obtained results have been compared to the others achieved by different approaches in the field and the benefits of the proposed methodology have been emphasized. The inference engine of the heuristic algorithms has been presented and the expert system knowledge-base construction discussed.

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Authors and Affiliations

Andrzej Pułka
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Abstract

The article discusses the phenomenon of folk beliefs in the late Middle Ages and the modern times, associated with Roman denarii. Found by villagers, Roman coins were called “St John’s heads”. In the known cases, cross pennies were deprived of the monetary features and perforated. The round object produced this way featured the anonymous emperor’s head that could have been taken for the head of St John on a platter. The perforation and removal of the monetary features was a magical practice that transformed the coin into an amulet, talisman or religious medallion. They may be seen as a symbol of the widespread cult of St John the Baptist.

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Authors and Affiliations

Wojciech Siwiak
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Abstract

This article examines Bolesław Prus's use of futurology and utopia in his short story Phantoms (Widziadła). A closer look at the story's images and their sequence not only gives us an insight into the author's philosophy of history but also reveals a utopian vision which can hardly be squared with the realism of his previous work. Thus ‘Widziadła’, written in 1911, can be seen as an important piece of evidence of a change in the writer's beliefs and worldview. It was at that late stage of his life that Prus, a hard-nosed realist and critic of the Romantics, turned into an impassioned idealist who, disillusioned with the world around him, sought refuge in literature. It was to be, however, a fiction like ‘Widziadła’, looking beyond the conventions of realism, unashamedly eclectic and visionary.

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Authors and Affiliations

Kamil Barski
ORCID: ORCID
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Abstract

Cells of a multicellular organism are genetically identical but differ in structure and function. This heterogeneity is created by several epigenetic mechanisms during the development of the organism. The epigenetic changes- including DNA methylation, histone post-translational modifications, chromatin remodeling and RNA interference have all been shown to control chromatin structure and regulate a plethora of cellular and organismal processes. There is a strong evidence that epigenetics play a crucial role in the development of diseases such as cancer, schizophrenia or metabolic disorders. The epigenetic regulation underlie memory formation or adaptation to external stimuli. The extent to which environmental effects can provoke epigenetic responses represents an exciting area of future research. Here we review the current knowledge about the epigenetic mechanisms and their relation to the human health and disease.

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Authors and Affiliations

Kamila Pawlicka
Patrick Perrigue
Jan Barciszewski

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