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Abstract

The study presents a concept of generation of micro-cracks (or cracks) in metal specimens in order to assess their material with respect to the thermal shock resistance. Both the method of conducting the experiment and the criteria of the assessment of the material resistance to the rapid temperature changes are discussed. The schematic diagram of the research stand used for repeated heating and rapid cooling of specimens, constructed in the Foundry Institute of the Częstochowa University of Technology, is presented. The proposed solution enables to maintain constant conditions of the experiment. The tests were held for flat specimens 70 mm long, 20 mm wide, and 5 mm thick, tapered over a distance of 15 mm towards both ends. The specimens were induction heated up to the specified temperature and then, in response to the signal produced by a pyrometer, dipped in the tank containing the cooling medium. The thermal shock resistance of the material can be assessed on the basis of either the total length of the micro-cracks arisen at the tapered parts of a specimen after a specified number of heating-and-cooling cycles, or the number of such cycles prior to the total damage of a specimen, or else the number of thermal cycles prior to generation of the first crack. The study includes an exemplary view of the metal specimen after the thermal shock resistance tests, as well as the illustrative microstructure of the vermicular cast iron which reveals a crack propagating from the edge towards the core of the material.

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Authors and Affiliations

A. Jakubus
ORCID: ORCID
M.S. Soiński
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Abstract

This article provides a detailed review of the ethnosurvey, a research methodology that has been widely applied to the study of migration for almost four decades. We focus on the application of ethnosurvey methods in Mexico and Poland, drawing on studies done in the former country since the early 1980s and, in the latter, since the early 1990s (including several post-2004 examples). The second case is particularly relevant for our analysis as it refers to a number of novel migration forms that have been identified in Central and Eastern Europe in the post-1989 transition period. Drawing on these studies, we consider the advantages and disadvantages of the ethnosurvey as a research tool for studying inter-national migration. Its advantages include its multilevel design, blend of qualitative and quantitative methods, reliance on retrospective life histories and multisited data collection strategy. These features yield a rich database that has enabled researchers to capture circular, irregular, short-term and se-quential movements. Its disadvantages primarily stem from its hybrid sampling strategy, which neces-sarily places limits on estimation and generalisability and on the technical challenges of parallel sampling in communities of both origin and destination. Here we argue that the ethnosurvey was never proposed and should not be taken as a universal methodology applicable in all circumstances. Rather it represents a specialised tool which, when correctly applied under the right conditions, can be ex-tremely useful in revealing the social and economic mechanisms that underlie human mobility, thus yielding a fuller understanding of international migration’s complex causes and diverse consequences in both sending and receiving societies.

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Authors and Affiliations

Paweł Kaczmarczyk
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Abstract

The ‘incriminated (suppressed) text’ and its removal remains the key object on the conceptual map of censorship studies. In this approach to censor ship the analysis focuses on demonstrable facts of official intervention in the media, the documentation of the process as well as the reconstruction of the effects of individual gagging orders for the author, the publisher and the editor in charge. An alternative, historical approach to censorship takes a much broader view of the subject. It looks at the institutions involved, their competences, procedures and aims (ranging from prevention to repression) as well as the tools at their disposal. The latter approach, systemic and comparative in scope, requires ‘digging up’ considerably more information than establishing the fact of a censor’s intervention.

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Authors and Affiliations

Grażyna Wrona
ORCID: ORCID

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