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Abstract

For many years, learning the competences to teach mathematics in early education at university has been associated with the ability to reproductively apply methodological guidelines. Currently, however, the need to not only understand the mathematical meanings given by teachers, but also students of the specialty, are seen to be important. This article attempts to engage in an interpretive line of thinking with regard to mathematics education, coming from the perspective of students learning to be early education teachers. Their understanding of the contexts for learning mathematical concepts, as well as their sensitivity to the processes of constructing mathematical knowledge by very young pupils, being a way of predicting what educational activities will be undertaken in the classroom in the future. This text is the result of qualitative analyses of written essays of early education students, where respondents had to make conceptualizations of their beliefs by justifying the selection of particular declarative statements. Students’ mathematical meanings were also uncovered in their strategies for solving mathematical problems for very young pupils. Moreover, the results of this analyses provides a context for reading the students’ understanding of mathematics learning processes.

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Authors and Affiliations

Alina Kalinowska
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Abstract

An original wireless sensor network for vibration measurements was designed. Its primary purpose is modal analysis of vibrations of large structures. A number of experiments have been performed to evaluate the system, with special emphasis on the influence of different effects on simultaneity of data acquired from remote nodes, which is essential for modal analysis. One of the issues is that quartz crystal oscillators, which provide time reading on the devices, are optimized for use in the room temperature and exhibit significant frequency variations if operated outside the 20–30°C range. Although much research was performed to optimize algorithms of synchronization in wireless networks, the subject of temperature fluctuations was not investigated and discussed in proportion to its significance. This paper describes methods used to evaluate data simultaneity and some algorithms suitable for its improvement in small to intermediate size ad-hoc wireless sensor networks exposed to varying temperatures often present in on-site civil engineering measurements.
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Authors and Affiliations

Miodrag Malović
Ljiljana Brajović
Zoran Mišković
Tomislav Šekara
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Abstract

The aim of this research was to experimentally analyse the possibility of using a rubber hose placed inside a pipeline to mitigate the water hammer phenomenon. The experiments were conducted using a steel pipeline with an inner diameter of 53 mm and an EPDM rubber hose with a diameter of 6 mm. Hydraulic transients were induced by a rapid closure of the valve located at the downstream end of the pipeline system. In order to analyse the influence of steady-state flow conditions on the maximum pressure increase, measurements were carried out for different values of initial pressure and discharge. The experimental results indicate that placing a rubber hose inside a pipeline can substantially attenuate valve-induced pressure oscillations. It was observed that the initial pressure has a significant influence on the capacity of the rubber hose to dampen the water hammer phenomenon. Comparative numerical calculations were performed using the Brunone–Vitkovský instant acceleration-based model of unsteady friction. It was demonstrated that this approach does not allow satisfactory reproduction of the observed pressure oscillations due to the viscoelastic properties of the EPDM hose used in the tests.
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Authors and Affiliations

Michał Kubrak
1
ORCID: ORCID

  1. WarsawUniversity of Technology, Faculty ofBuilding Services,Hydro and Environmental Engineering, ul. Nowowiejska 20, 00-653 Warsaw, Poland

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