Periodica Polytechnica (Budapest University of Technology and Economics)
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30 év a helytörténet szolgálatában: Jubilál a Magyar Könyvtárosok Egyesülete Helyismereti Könyvtárosok Szervezete
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Kinetic and Chemical Analysis of Pyrolysis in Bambusa vulgaris Leaves and Derived Fibers
Get PDFBamboo, a perennial and monocarpic plant, holds immense potential beyond its commonly recognized applications. In this study, fiber was extracted from bamboo leaves. Pyrolytic kinetic studies were done on leaves and the extracted fibers, utilizing thermogravimetry and derivative thermogravimetry (TG/DTG) data obtained at heating rates 10, 20, and 30 K/min within the temperature range of 298–1093 K. Model-free methods such as Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), and Friedman were employed to calculate the activation energy (Ea) and the pre-exponential factor (A). For leaves, the calculated Ea values were found to be 283 kJ/mol (KAS), 279 kJ/mol (OFW), and 318 kJ/mol (Friedman), while the A values were determined as 7.2 × 1043 s−1 (KAS), 1.07 × 1043 s−1 (OFW), and 5.7 × 1045 s−1 (Friedman). In the case of fiber, the Ea values were found to be 162 kJ/mol (KAS), 164 kJ/mol (OFW), and 165 kJ/mol (Friedman), with corresponding A of 4.6 × 1015 s−1 (KAS), 5.6 × 1013 s−1 (OFW), and 348 × 1013 s−1 (Friedman). Additionally, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) analyses were conducted on both leaves and fiber
Study of the Gap Parameters of Cement Mortar Specimens Based on X-ray Tomography
Get PDFConcrete is one of the most widely used structural materials next to steel. This justifies a detailed study of the material structure to understand the influence of the production parameters on the properties of the concrete. The pore structure of concretes has a major influence on their practical use, as it impacts their resistance to environmental degradation (e.g., frost resistance). In the present study, I have investigated concrete and cement mortar specimens with different water-cement ratios using micro-CT (or micro X-ray tomography) to determine the pore structure and the pore gap parameters of the specimens. It can be concluded that with an increasing water-cement ratio the overall porosity of the samples and the number of large pores (1 mm3) show a decreasing trend, in contrast, the gap parameter shows an enhancing trend. It can also be concluded that any pore-forming additives cause significant changes in the structure
Exploring Academic Mobility Experiences of Russian University Faculty Members
No full textThe paper outlines findings of an exploratory research that investigates international academic mobility experiences of faculty members in Russian universities as part of higher education institutions’ internationalization efforts. The study aims to get an in-depth understanding of academic staff’s motivation, personal expectations and the perceived outcomes of the mobility experience, as well as its influence on teaching and research activities after the mobility period. The study refers to the university context as an ecosystem and discovers the relations between the system levels as a meaningful part of the faculty mobility experience. Ten faculty members employed in different Russian universities were interviewed about their experience of academic mobility abroad. The interviews were analyzed using thematic analysis. The study allowed to identify and examine 3 dimensions of academic mobility in the Russian context from the perspective of university faculty: (1) personal motivation and benefits of the participating faculty members on the microlevel of the university ecosystem; (2) institutional support and barriers that occur during the preparation and mobility process that reflect the interactions between the micro- and meso-levels of the ecosystem; (3) effects of completed academic mobility on further professional performance of the faculty members, both research and teaching
Komplex szövegértési vizsgálat első éves egyetemisták körében: A szövegértés új megközelítési szempontjai
No full textThe description and measurement options for the relationship between mathematics and language include the examination of text comprehension. This competence has a wide range of applications. The examination of text comprehension contributes to the measurement of abstract, logical thinking. Text comprehension is an important part of success in both education and the labor market. To describe this ability, a measurement method is needed that describes the levels of interpretation of the competence, its possible deficits, and the areas of development in a more complex way. This micro-research measured the level of inductive and combinatorial thinking ability in the thinking of university students. The study thus aimed to provide a more accurate picture of the more combined, abstract measurement options for text comprehension. The results can be used in both higher education and public education.
A matematika és a nyelv kapcsolatának leírási és mérési lehetőségei közé tartozik a szövegértés vizsgálata is. Ennek a kompetenciának széles körű alkalmazási területe van. A szövegértés vizsgálata hozzájárul az absztraktív, logikai gondolkodás méréséhez. A szövegértés mind az oktatásban, mind a munkaerőpiacon az érvényesülés, a sikeresség egyik fontos része. Ezen képesség leírásához olyan mérési módszerre van szükség, amely komplexebb módon írja le a kompetencia értelmezési szintjeit, esetleges deficitjét, s a fejlesztés tartományait. Jelen mikrokutatás egyetemi hallgatók gondolkodásában mérte az induktív és kombinatív gondolkodási képesség szintjét. A vizsgálat ezzel pontosabb képet kívánt adni a szövegértés kombináltabb, absztraktabb mérési lehetőségeihez. Az eredményeket mind a felsőoktatásban, mind a közoktatásban fel lehet használni.
 
Determination of Experimental Characteristics of a Jet-vortex Pump
Get PDFA methodology has been developed and the results of experimental studies of high-pressure jet-vortex pump models with a mixing chamber and working nozzle area ratio of 3.429 and 3.795 have been obtained. In the flow part of the pump, inclined guide elements for swirling the mixed flows are installed. An increase in the velocity of swirling screw jets increases the level of turbulence, intensifies the energy exchange of the mixed media, and improves the conditions for transferring kinetic energy from the working flow to the injected one. Improvement of the flow mixing mechanism allows increasing the energy efficiency of jet pumps. The velocity of swirling screw jets is determined by the angle of inclination of the guide elements and the flow rate of the mixed flows. The efficiency of simultaneous swirling of the mixed media may be less than the efficiency of swirling a separate flow if there is a difference in the directions of the velocity vectors of the swirling jets. There has been obtained the dependence of the injection coefficient on the Reynolds number of the working flow, pressure and energy characteristics for a straight-through jet pump for the case of swirling of the exclusively injected flow and simultaneous swirling of the working and injected flows. According to the results of the conducted studies, an increase in the injection coefficient, relative pressure and efficiency caused by swirling of the mixed flows was established by 26.34%, 19.43% and 23.75%, respectively