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Rotor dynamics - four open questions

Kiciński Jan

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e139791

EN

Despite many years of development in the field of rotor dynamics, many issues still need to be resolved. This is due to the fact that turbomachines, even those with low output power, have a very complex design. The author of this article would like to signal these issues in the form of several questions, to which there are no precise answers. The questions are as follows: How can we build a coherent dynamic model of a turbomachine whose some subsystems have non-linear characteristics? How can we consider the so-called prehistory in our analysis, namely, the relation between future dynamic states and previous ones? Is heuristic modelling the future of rotor dynamics? What phenomena may occur when the stability limit of the system is exceeded? The attempt to find answers to these questions constitutes the subject of this article. There are obviously more similar questions, which encourage researchers from all over the world to further their research.

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Gemstones of eastern Kazakhstan

Chlachula Jiri

Geologos

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2020

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Vol. 26, No. 2

139--162

EN

An overview is presented of gemstones from eastern Kazakhstan in terms of their geographical distribution, geological provenance and genesis, gemmological characteristics, historical use and current applications. Locally occurring precious, semi-precious and decorative stones were extracted and traded along the northern part of the Silk Road that traversed the area in earlier historical times. Currently, non-metallic minerals, which largely originate from mafic igneous and metamorphic bodies of the Altay and Kalba Mountains of Kazakhstan, still are insufficiently known and exploited industrially only marginally. For the present study, selected depositories of coloured stones at the Mineralogy Museum of the East Kazakhstan State Technical University were used, supplemented by the newly collected material during personal fieldwork in the southern Altay between 2005 and 2015. Standard documentation of the gemstones selected is provided, alongside with their known occurrence sites and an evaluation of the perspective gemstone-bearing deposits with respect to regional morphostructural bedrock characteristics. The most precious gemstones include topaz, corundum (sapphire and ruby), beryl (emerald and aquamarine), coloured tourmalines, agates as well as diamonds. Despite the great variety, the majority of these traditionally most valued stones are currently commercially not viable, unlike high-quality decorative stones.

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Archaeological research results of the settlement micro-region in the area of Ulów in Middle Roztocze in the light of the project “Roztocze – the ancient terra incognita?...”

Niezabitowska-Wiśniewska B.

Folia Quaternaria

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2017

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nr 85

5--47

EN

Many years of archaeological research near Ulów in the Middle Roztocze contributed to the discovery of a multicultural settlement complex, functioning from the Palaeolithic to the 17th/18th century, refuting the existing myth of Roztocze as a white spot on the map of prehistoric settlement. The results of an archaeological research became the basis for the implementation of the project “Roztocze – the ancient terra incognita? (Settlement micro-region in the area of Ulów in Middle Roztocze in the prehistory and its background. Interdisciplinary studies)”. Comprehensive and interdisciplinary research has enabled the reconstruction of settling processes in the micro-region of Ulów in prehistory and in the Modern Age. The main reason for the rise of a multicultural enclave, encompassed by areas devoid of traces of the prehistoric settlement, should be seen in the favourable environmental conditions. Many aspects of the ritual and everyday life of particular archaeological cultures populations recorded in Ulów, do not find analogies in other areas of Poland. A series of several dozen radiocarbon dates confirmed all the stages of the Ulów micro-region settlement recorded in the archaeological sources. It also highlighted a whole range of the problems related to the interpretation of some cultural phenomena, especially with regard to the intensive settlement of the Corded Ware culture and the Wielbark culture, as well as the early phase of the Migration Period and initial phases of the early Middle Ages.

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Regionalna wymowa procesów antropogenizacji regionu środkowej Obry na podstawie badań osadów jeziora Wonieść

Hildebrandt-Radke I., Spychalski W., Lutyńska M.

Landform Analysis

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2011

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Vol. 16

92-97

EN

The study was aimed at anthropogenization processes of the Kościan Plain. They are noticeable in local palynological diagrams (eg. at the archaeological site in Bruszczewo) as well as on settlement maps of the Polish Archaeological Record Project. The goal was to determine whether the processes were perceptible also in a regional scale, in deposits of the biggest water body in the examined area, located 15 km to the east from Bruszczewo. Anthropogenic participation in changes of plant cover is clearly visible in the local diagram from Bruszczewo. While compared with the mentioned, anthropogenic influence in deposits of Wonieść Lake is rather inconspicuous. In the Neolithic and Early Bronze Periods, percentage of herbaceous plants (amount of grasses and herbs) maintained the level of 10%. Increase in NAP is marked not earlier than in the Roman Iron Age, and then from the Early Middle Ages until the present time (Dörfler, to be published soon). Comparison of palynological results to sedimentological analyses indicates that periods of increased values of CerealiaandPlantago lanceolataindices are correlated with inflow of mineral material to lacustrine water body. Larger fractions were observed there i.e. fine- and medium-grained sands, and even gravels as well as organic matter. In the geochemical record for the same periods, an increased percentage of trace elements can be visible (however their distinctive escalation is manifested not earlier than in the Middle Ages). These changes are accompanied by intensified eutrophication index (phosphorus percentage) as well as by occurrence of diatoms, which prefer eutrophic conditions.