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Abstract

Mathematical models of electric an arc with disturbed geometric sizes were created based on initial assumptions adopted from theMayr and Cassie models. Two cases of approximation of arc characteristics were considered separately. The Mayr–Voronin model was created in the low-current range with an exponential dependence of conductance on plasma enthalpy. However, the Cassie–Voronin model created is valid in the high-current range with a linear dependence of conductance on plasma enthalpy. In addition, the effect of two different assumptions about the method of energy dissipation, proportional to the lateral surface of the column or proportional to the volume of the column, on the parameters of both mathematical models was compared. It has been shown that under constant geometrical parameter values, created models can be reduced to classic Mayr and Cassie models. Then, these modelswere modified by taking into account the additional increase in heat dissipation as the current increases. Increasing voltage and current characteristics correspond to such an arc. Using the computer simulations, the effectiveness of using developed mathematical models in mapping the dynamic characteristics of the electric arc has been shown.
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Bibliography

[1] Krouchinin A.M., Sawicki A., Modelling of the constricted arc in plasma generators, Monographs series, no. 109, The Publishing Office of Częstochowa University of Technology, Częstochowa (2005).
[2] Solonenko O.P., Thermal Plasma Torches and Technologies, Cambridge International Science Publishing, vol. 1 (2000).
[3] Jaroszynski L., Stryczewska H.D., Computer simulation of the electric discharge in GlidArc plasma reactor, 3rd International Conference: Electromagnetic devices and processes in environment protection ELMECO-3, pp. 31–36 (2000).
[4] Schavemaker P.H., van der Sluis L., An Improved Mayr-Type Arc Model Based on Current-Zero Measurements, IEEE Trans. Power Delivery, vol. 15, no. 2, pp. 580–584 (2000).
[5] Kopersak V.M., The theory of welding processes – 1, KPI (in Ukrainian), Kiev (2011).
[6] Zalessky A.M., Fundamentals of the theory of electrical apparatus, Higher School Publishing House (in Russian), Moscow (1974).
[7] Taev I.S., Electrical contacts and arcing devices of low voltage devices, Energy Publishing House (in Russian), Moscow (1973).
[8] Marciniak L., Dynamic models of short-circuit arc for networks with low ground fault current, Energy Archive (in Polish), vol. 37, pp. 357–67 (2007).
[9] Ziani A., Moulai H., Hybrid model of electric arcs in high voltage circuit breakers, Electric Power Systems Research, vol. 92, pp. 37–42 (2012).
[10] Voronin A.A., Improving the efficiency of contact-extinguishing systems of high-current switching devices with an extending arc, Abstract of thesis (in Russian), Samara (2009).
[11] Ciok Z., Mathematical models of connecting arc,Warsaw University of Technology (in Polish),Warsaw (1995).
[12] Sawicki A., Models of adjustable length electric arc,Wiadomosci Elektrotechniczne (in Polish), no. 7, pp. 15–19 (2012).
[13] Berger S., Mathematical approach to model rapidly elongated free-burning arcs in air in electric power circuits, ICEC 2006, 6–9 June 2006, Sendai, Japan (2006).
[14] Pentegov I.V., Sydorets V.N., Comparative analysis of models of dynamic welding arc, The Paton Welding Journal, no. 12, pp. 45–48 (2015).
[15] Sawicki A., The universal Mayr–Pentegov model of the electric arc, Electrical Review, vol. 94, no. 12, pp. 208–211 (2019), DOI: 10.15199/48.2019.12.47.
[16] Krouchinin A.M., Sawicki A., A theory of electrical arc heating, The Publishing Office of Technical University of Częstochowa, Częstochowa (2003).
[17] Sawicki A., Arc models for simulating processes in circuits with a SF6 circuit breaker, Archives of Electrical Engineering, vol. 68, no. 1, pp. 147–159 (2019), DOI: 10.24425/aee.2019.125986.
[18] Katsaounis A., Heat flow and arc efficiency at high pressures in argon and helium tungsten arcs, Welding Research Supplement I, pp. 447-s- 454-s (1993).
[19] Kalasek V., Measurements of time constants on cascade d.c. arc in nitrogen, TH-Report 71-E18, Eindhoven, pp. 1–30 (1971).
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Authors and Affiliations

Antoni Sawicki
1
ORCID: ORCID

  1. Association of Polish Electrical Engineers (NOT-SEP), Czestochowa Division, Poland
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Abstract

A questionnaire inquiry on response to wind turbine noise was carried out on 361 subjects living in the vicinity of 8 wind farms. Current mental health status of respondents was assessed using Goldberg General Health Questionnaire GHQ-12. For areas where respondents lived, A-weighted sound pressure levels (SPLs) were calculated as the sum of the contributions from the wind power plants in the specific area.

Generally, 33.0% of respondents were annoyed outdoors by wind turbine noise at the calculated A-weighted SPL of 31-50 dB, while indoors the noise was annoying to 21.3% of them. The proportion of subjects evaluating the noise produced by operative wind turbines as annoying decreased with increasing the distance from the nearest wind turbine (27.6% at the distance of 400-800 m vs 14.3% at the distance above 800 m, p < 0.016). On the other hand, the higher was the noise level, the greater was the percentage of annoyed respondents (14.0% at SPL up to 40 dB vs 28.1% at SPL of 40-45 dB, p < 0.016). Besides noise and distance categories, subjective factors, such as general attitude to wind turbines, sensitivity to landscape littering and current mental health status, were found to have significant impact on the perceived annoyance. About 50% of variance in annoyance rating might be explained by the aforesaid subjective factors.

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Authors and Affiliations

Małgorzata Pawlaczyk-Łuszczyńska
Adam Dudarewicz
Kamil Zaborowski
Małgorzata Zamojska-Daniszewska
Małgorzata Waszkowska
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Abstract

Introduction: Uterine leiomyoma is the most widespread benign tumor affecting women of childbearing age. There are still gaps in the understanding of its pathogenesiss. Telocytes are unique cells described in greater than 50 different locations inside the human body. The functional relationship of cells could clarify the pathogenesis of leiomyomata. In the current study, we focused on the identification of telocytes in all regions of the human uterus to explain their involvement in leiomyoma development.

Materials and Methods: Tissue samples from a healthy and myomatous uterus were stained for c-kit, tryptase, CD34 and PDGFRα to identify telocytes. Routine histology was performed to analyze tissue morphology and collagen deposits.

Results: Telocytes were detected in the cervix, corpus of the uterus and leiomyoma. The density of telocytes in fibroid foci was reduced compared with normal myometrium.

Conclusions: Our results demonstrated the existence of telocytes in all parts of the human body affected and unaff ected by leiomyoma of the uterus. In addition, telocytes were also present in leiomyoma foci. Our results suggest that the reduced density of telocytes is important for the pathomechanisms of myometrial growth, demonstrating its value as a main component of the myomatous architecture.

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Authors and Affiliations

Veronika Aleksandrovych
Magdalena Białas
Artur Pasternak
Tomasz Bereza
Marek Sajewicz
Jerzy Walocha
Krzysztof Gil
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Abstract

The purpose of the article is to systematize the main issues related to the encounter of Christianity with Latin American cultures. The study is based on both Latin American theological publications and various documents of the Roman Catholic Church. In the first part the problem of Christianity’s encounter with cultures of this region from historic perspective is discussed by pointing out to its negative, ambiguous and positive aspects. The second part is devoted to classification of culture circles, significant from the point of view of evangelization and inculturation (cultures of urban agglomeration, rural regions, Indian and Afro-Latin American cultures, poverty, elites, cyber culture and popular culture). In the final section we paid attention to the issue of up-coming culture and its trends (modernism and postmodernism, secularism, socio-political ideologies, the role of mass media, the tensions between globalization process and appreciation of local traditions).

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Authors and Affiliations

Ks. Andrzej Pietrzak SVD
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Abstract

Forms and means of theatrical expression in ancient Roman culture, abounding in the diversity of artistic forms, had perfect conditions for development. The cultural activity of man has naturally created the need for stage performances. This publication presents a detailed analysis of the provisions of the synods summoned and debating in the 4th and 5th centuries, A.D. T heir content was carefully referenced, in relation to actors, mimes and circus drivers. The reason for such an outline of research is the classification common to all these professions generally describing them as representatives of performing arts. The analysis on this matter was subjected, inter alia, to canons proclaimed in Elvira (306), Arles (314), Carthage (15 June 401), Hippo (427) and again in Arles (442–506). In order to more fully illustrate the issue cited in the subject, the situation of representatives of performing arts was also discussed on the example of actors in Roman public law and a short description of the history of synods in the ancient Church was presented.

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Authors and Affiliations

Maria Piechocka-Kłos
ORCID: ORCID
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Abstract

The paper considers method of determination of solar radiation amount falling on arbitrarily oriented surface of a structure. Provided method allows calculation of influence of structure’s geographical coordinates, spatial orientation of structure’s surface, day of year and time of day on received amount of solar radiation. The method is intended for determination of thermal stresses and deformations of sheet steel structures caused by action of direct solar radiation. Examples show usage of provided method.

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Authors and Affiliations

O.I. Kordun

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