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Number of results: 6
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Abstract

Investigations were carried out in the regions of the Hornsund Station, Spitsbergen at summer 1979. The aim of the studies was to determine the effect of the Station on the natural environment around the Station. After taking an inventory of the sources of pollution and in result of the determination of the range of the pressure of anthropogenic factors the whole area under degradation was divided into three parts: an area without possibilities of recultivation, a devastated area and an area of normal natural environment. It was found thąt the main source of the contamination of tundra are fuels derived from mineral oil. The distribution of fuel concentrations in the soil corresponds to the direction of the slope of the ground and the flow of the surface waters. Mechanical transformation of the surface of the tundra is also an outcome of the degradation.

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Authors and Affiliations

Anna Krzyszowska
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Abstract

In this paper, flow systems which are commonly used in fittings elements such as contractions in ice slurry pipelines, are experimentally investigated. In the study reported in this paper, the consideration was given to the specific features of the ice slurry flow in which the flow behaviour depends mainly on the volume fraction of solid particles. The results of the experimental studies on the flow resistance, presented herein, enabled to determine the loss coefficient during the ice slurry flow through the sudden pipe contraction. The mass fraction of solid particles in the slurry ranged from 5 to 30%. The experimental studies were conducted on a few variants of the most common contractions of copper pipes: 28/22 mm, 28/18 mm, 28/15 mm, 22/18 mm, 22/15 mm and 18/15 mm. The recommended (with respect to minimal flow resistance) range of the Reynolds number (Re about 3000-4000) for the ice slurry flow through sudden contractions was presented in this paper.

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Authors and Affiliations

Łukasz Mika
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Abstract

Magnetic circuits of electromagnetic energy converters, such as electrical machines, are nowadays highly utilized. This proposition is intrinsic for the magnetic as well as the electric circuit and depicts that significant enhancements of electrical machines are difficult to achieve in the absence of a detailed understanding of underlying effects. In order to improve the properties of electrical machines the accurate determination of the locally distributed iron losses based on idealized model assumptions solely is not sufficient. Other loss generating effects have to be considered and the possibility being able to distinguish between the causes of particular loss components is indispensable. Parasitic loss mechanisms additionally contributing to the total losses originating from field harmonics, non-linear material behaviour, rotational magnetizations, and detrimental effects caused by the manufacturing process or temperature, are not explicitly considered in the common iron-loss models, probably even not specifically contained in commonly used calibration factors. This paper presents a methodology being able to distinguish between different loss mechanisms and enables to individually consider particular loss mechanisms in the model of the electric machine. A sensitivity analysis of the model parameters can be performed to obtain information about which decisive loss origin for which working point has to be manipulated by the electromagnetic design or the control of the machine.
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Authors and Affiliations

Simon Steentjes
Georg Von Pfingsten
Andreas Ruf
Marco Hombitzer
David Franck
Kay Hameyer Rwth
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Abstract

This paper presents an evaluation of the Hypoplastic Clay constitutive model for finite element analysis of deep excavations and displacements induced by excavations in the influence zone. A detailed description and formulation of the Hypoplastic Clay soil model is included. A parametric case study of a deep excavation executed in Pliocene clays is presented. FE analysis was performed using several soil models (Mohr-Coulomb, Modified Mohr-Coulomb, Drucker-Prager, Modified Cam-Clay, Hypoplastic Clay) and the results were compared to in-situ displacements measurements taken during construction. Final conclusions concerning the suitability of the Hypoplastic Clay model for deep excavation modelling in terms of accurate determination of horizontal displacements of the excavation wall, the uplift of the bottom of excavation, and, most importantly,vertical displacements of the terrain in the vicinity of the excavation are presented.

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Authors and Affiliations

M. Mitew-Czajewska
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Abstract

The article deals with the evolution of the Polish national identity in the 19th century in the European context. The Author shows why traditional methods could not explain why this ideology developed and proposes her own method to analyze this phenomenon.
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Authors and Affiliations

Alix Landgrebe
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Abstract

The aim of the presented paper is to show the history of the development of research on social minorities in the environment of Bialystok sociologists. This research center, located on the north-eastern borderland of Poland, was one of the first in Poland to develop research in the field of borderland sociology. With time, the research subject has been expanded, from the analysis of the assimilation of the Belarusian minority to the contemporary face of the idea of a multicultural society, discussing not only nationality, religiosity, but also non-heteronormities.

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Authors and Affiliations

Małgorzata Bieńkowska

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