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Abstract

The Bulletin of the Polish Academy of Sciences: Technical Sciences (Bull.Pol. Ac.: Tech.) is published bimonthly by the Division IV Engineering Sciences of the Polish Academy of Sciences, since the beginning of the existence of the PAS in 1952. The journal is peer‐reviewed and is published both in printed and electronic form. It is established for the publication of original high quality papers from multidisciplinary Engineering sciences with the following topics preferred: Artificial and Computational Intelligence, Biomedical Engineering and Biotechnology, Civil Engineering, Control, Informatics and Robotics, Electronics, Telecommunication and Optoelectronics, Mechanical and Aeronautical Engineering, Thermodynamics, Material Science and Nanotechnology, Power Systems and Power Electronics. Journal Metrics: JCR Impact Factor 2018: 1.361, 5 Year Impact Factor: 1.323, SCImago Journal Rank (SJR) 2017: 0.319, Source Normalized Impact per Paper (SNIP) 2017: 1.005, CiteScore 2017: 1.27, The Polish Ministry of Science and Higher Education 2017: 25 points. Abbreviations/Acronym: Journal citation: Bull. Pol. Ac.: Tech., ISO: Bull. Pol. Acad. Sci.-Tech. Sci., JCR Abbrev: B POL ACAD SCI-TECH Acronym in the Editorial System: BPASTS.
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Abstract

The paper contains a description of a multiscale algorithm based on the boundary element method (BEM) coupled with a discrete atomistic model. The atomic model uses empirical pair-wise potentials to describe interactions between atoms. The Newton-Raphson method is applied to solve a nanoscale model. The continuum domain is modelled by using BEM. The application of BEM reduces the total number of degrees of freedom in the multiscale model. Some numerical results of simulations at the nanoscale are shown to examine the presented algorithm.
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Abstract

In the recent years a tendency for design of increasingly slender structures with the use of high performance concrete has been observed. Moreover, the use of high performance concrete in tunnel structures, subject to high loads with possibility of extreme loads occurrence such as fire, has an increasing significance. Presented studies aimed at improving high performance concrete properties in high temperature conditions (close to fire conditions) by aeration process, and determining high temperature impact on the concretes features related to their durability. In this paper it has been proven that it is possible to obtain high performance concretes resistant to high temperatures, and additionally that modification of the concrete mix with aerating additive does not result in deterioration of concrete properties when subject to water impact in various form.
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Abstract

The propagation of EEG activity during the Continuous Attention Test (CAT) was determined by means of Short-time Directed Transfer Function (SDTF). SDTF supplied the information on the direction, spectral content and time evolution of the propagating EEG activity. The differences in propagation for target and non-target conditions were found mainly in the frontal structures of the brain.
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Abstract

Rynek energii w Polsce sukcesywnie ewoluuje w kierunku promowania i intensywnego rozwoju energetyki obywatelskiej przekładającego się na różnego rodzaju inicjatywy i działania o zasięgu regionalnym i lokalnym. Jednym z takich działań jest dążenie do szeroko rozumianego stworzenia właściwych warunków do budowy samowystarczalności energetycznej na poziomie gmin. Cel ten ma charakter perspektywiczny i może być ciekawą alternatywą dla energetyki zawodowej w obszarze poprawy bezpieczeństwa energetycznego i tworzenia zasobów wytwórczych bazujących na lokalnej strukturze energy-mix. Równolegle tworzone są regulacje, mechanizmy i narzędzia wspierające realizację tych celów. W artykule opisany został przykładowy model postępowania, który wpisuje się w realizację celu uzyskania samowystarczalności energetycznej jednej z gmin rolniczych. Koncepcja ta dotyczy budowy klastra energii na podstawie partnerstwa publiczno-prywatnego. W ramach inicjatyw klastrowych możliwe staje się stworzenie lokalnych obszarów samowystarczalności energetycznej, gwarantującej uczestnikom klastra osiąganie korzyści na poziomie zarówno partykularnym, jak i zbiorowym. Na poziomie indywidualnych korzyści odbiorcy mogą uzyskać tańszą energię elektryczną i ciepło, a wytwórcy korzystniejsze względem rynkowych ceny sprzedaży energii. W ramach dodatkowych korzyści uzyskuje się pobudzenie gospodarki na poziomie lokalnym i regionalnym, wzrost konkurencyjności oraz poprawę bezpieczeństwa dostaw mediów. W artykule przedstawiono także wyniki analiz bilansu energetycznego gminy wraz z rekomendacją w zakresie technologii gwarantujących uzyskanie samowystarczalności energetycznej. Dla wybranej technologii zilustrowany został proces realizacji inwestycji w źródło wytwórcze wraz z oceną przychodowo-kosztową, modelem finansowania i bilansem korzyści po stronie uczestników klastra. Dowiedziona została tym samym teza, że klastry energii mogą być skutecznym narzędziem realizacji celu samowystarczalności energetycznej gmin.
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Abstract

In this paper an attempt to determine the relationship between the electrical resistivity and the tensile strength and hardness of cast iron of carbon equivalent in the range from 3.93% to 4.48%. Tests were performed on the gray cast iron for 12 different melts with different chemical composition. From one melt poured 6 samples. Based on the study of mechanical and electro-resistive determined variation characteristics of tensile strength, hardness and resistivity as a function of the carbon equivalent. Then, regression equations were developed as power functions describing the relationship between the resistivity of castings and their tensile strength and hardness. It was found a high level of regression equations to measuring points, particularly with regard to the relationship Rm=f(ρ). The obtained preliminary results indicate the possibility of application of the method of the resistance to rapid diagnostic casts on the production line, when we are dealing with repeatable production, in this case non variable geometry of the product for which it has been determinated before a regression equation.
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Abstract

The publication presents the results of examination of selected carburizers used for cast iron production with respect to their electric resistance. Both the synthetic graphite carburizers and petroleum coke (petcoke) carburizers of various chemical composition were compared. The relationships between electrical resistance of tested carburizers and their quality were found. The graphite carburizers exhibited much better conductivity than the petcoke ones. Resistance characteristics were different for the different types of carburizers. The measurements were performed according to the authors’ own method based on recording the electric current flow through the compressed samples. The samples of the specified diameter were put under pressure of the gradually increased value (10, 20, 50, 60, and finally 70 bar), each time the corresponding value of electric resistance being measured with a gauge of high accuracy, equal to 0.1μΩ. The higher pressure values resulted in the lower values of resistance. The relation between both the thermal conductance and the electrical conductance (or the resistance) is well known and mentioned in the professional literature. The results were analysed and presented both in tabular and, additionally, in graphic form.
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