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.
Autor definiuje pojęcie kultury przez odniesienie do szczególnej kategorii znaczeń normatywnych, czyli wartości. System wartości zorganizowany jest wokół trzech wartości najbardziej ogólnych i fundamentalnych: prawdy, dobra i piękna. Odpowiednio mówić można o trzech domenach kultury: kulturze poznawczej, kulturze moralnej i kulturze estetycznej. Desygnatami kultury poznawczej są przekonania, poglądy, opinie podzielane przez członków społeczeństwa. Desygnatami kultury moralnej są relacje łączące jednostki w przestrzeni międzyludzkiej. Desygnatami kultury estetycznej są szczególnego typu wytwory należące do sztuki artystycznej lub użytkowej. Podobieństwo wartości w każdym z tych trzech obszarów stanowi silny czynnik wytwarzający więzi społeczne i wspólnoty, a także tożsamości społeczne. Kultura jest fundamentem żywej i bogatej tkanki społecznej, społeczeństwa obywatelskiego.
W artykule zestawione zostają dwie koncepcje okazjonalności. Pierwsza, standardowa i wąska, okazjonalność wyrażenia wiąże ściśle z jego znaczeniem i regulowanym przez nie związkiem kontekstu z określoną rolą wyrażenia. Druga, szersza i wywodząca się z prac Jerzego Pelca, określa okazjonalność w kategoriach potencjalnej zmienności ogólnej charakterystyki semiotycznej wyrażenia przy zachowaniu jego znaczenia. W tekście wprowadzone zostaje pojęcie matrycy pragmatycznej, które służy do schematycznego przedstawiania zmienności kontekstowej. Rekapituluję także krótko poglądy Jerzego Pelca na znaczenie (sposób użycia) i użycie oraz wskazuję krótko na związki jego podejścia ze współczesnymi debatami wokół kontekstualizmu oraz statusu wypowiedzi niezdaniowych.
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.
The main reason of a cavitational destruction is the mechanical action of cavitation pulses onto the material’s surface. The course of cavitation destruction process is very complex and depends on the physicochemical and structural features of a material. A resistance to cavitation destruction of the material increases with the increase of its mechanical strength, fatigue resistance as well as hardness. Nevertheless, the effect of structural features on the material’s cavitational resistance has been not fully clarified. In the present paper, the cavitation destruction of ZnAl4 as cast alloy was investigated on three laboratory stands: vibration, jet-impact and flow stands. The destruction mechanism of ZnAl4 as cast alloy subjected to cavitational erosion using various laboratory stands is shown in the present paper.
Hybrid filter material was obtained via modification of polypropylene (PP) nonwoven with nanosize zinc oxide particles of a high aspect ratio. Modification was conducted as a three-step process, a variant of hydrothermal method used for synthesis of nano-ZnO, adopted for coating three dimensional polymeric nonwoven filters. The process consisted of plasma treatment of nonwoven to increase its wettability, deposition of ZnO nanoparticles and low temperature hydrothermal growth of ZnO rods. The modified nonwovens were investigated by a high resolution scanning electron microscopy (HR-SEM). It has been found that the obtained hybrid filters offer a higher filtration efficiency, in particular for so called most penetrating particle sizes.
Tytułowe kategorie znaczenia, rozumowania i normatywności wyznaczają temat i cel artykułu. Jego celem jest odpowiedź na główne pytanie: czy między znaczeniem i rozumowaniem istnieje jakiś związek? A jeżeli tak, to jeden, czy wiele? Jaki? Jakie? Udzielając pozytywnej odpowiedzi, w punkcie (1) prezentuję definicję rozumowania (wnioskowania), a w punkcie (2) rozróżniam i przedstawiam związki formalne oraz pozaformalne. Związki formalne są opracowywane przez logikę. Nazwy – z określonymi znaczeniami, czyli pojęciami – tworzą zdania (związki wewnątrzzdaniowe). Ich znaczenia to sądy. Zdania pełnią funkcje przesłanek i wniosku w rozumowaniu (związki międzyzdaniowe). Do związków pozaformalnych można zaliczyć: związek między zdaniem a stanem rzeczy, do którego zdanie się odnosi (referencja i łącząca się z nią własność prawdziwości zdania). Inne związki pozaformalne to: związek przyczynowo-skutkowy, związek następstwa czasowego, związek przestrzenny i związki normatywne.
The aim of this paper was to determine the effect of heat treatment for the corrosion resistance of the ZnAl40Ti2Cu alloy under “acid rain” conditions. ZnAl40TiCu alloy after supersaturation and after supersaturation and aging was studied. Potentiodynamic studies, potentiostatic studies and studies on structure of the alloy top layer of samples after corrosion tests were carried out. These investigations indicated a significant influence of heat treatment on corrosion resistance of the ZnAl40Ti2Cu alloy. The highest increase in corrosion resistance comparing to the alloy in the as-cast condition may be obtained by supersaturation. A significant influence of the aging temperature and time on corrosion resistance was proved.
As-cast Mg-6Li-0.3Zn-0.6Y and Mg-6Li-1.2Zn-1.2Y (wt%) alloys were prepared and extruded at 260 oC with an extrusion ratio of 25. The microstructure and mechanical behavior of as-cast and extruded alloys are reported and discussed. The results show that Mg-6Li-1.2Zn- 1.2Y alloy is composed of α-Mg, β-Li, and W-Mg3Zn3Y2 phases while Mg-6Li-0.3Zn-0.6Y alloy contains α-Mg, β-Li, W-Mg3Zn3Y2 phase and X-Mg12ZnY. After hot extrusion, the microstructure of specimens is refined and the average grains size of extruded alloys is 15 μm. Dynamic recrystallization occurs during the extrusion, leading to grain refinement of test alloys. Both the strength and elongation of test alloys are improved by extrusion. The extruded Mg-6Li-0.3Zn-0.6Y alloy possesses an ultimate strength of 225 MPa with an elongation of 18% while the strength and elongation of Mg-6Li-1.2Zn-1.2Y alloy are 206 MPa and 28%, respectively. The X-phase in Mg-6Li-0.3Zn- 0.6Y is beneficial to the improvement of strength, but will lead to the decrease of ductility.
Constantly developing nanotechnology provides the possibility of manufacturing nanostructured composites with a polymer matrix doped with ceramic nanoparticles, including ZnO. A specific feature of polymers, i.e. ceramic composite materials, is an amelioration in physical properties for polymer matrix and reinforcement. The aim of the paper was to produce thin fibrous composite mats, reinforced with ZnO nanoparticles and a polyvinylpyrrolidone (PVP) matrix obtained by means of the electrospinning process and then examining the influence of the strength of the reinforcement on the morphology and optical properties of the composite nanofibers. The morphology and structure of the fibrous mats was examined by a scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS) and Fourier-transform infrared spectroscopy (FTIR). UV –Vis spectroscopy allowed to examine the impact of zinc oxide on the optical properties of PVP/ZnO nanofibers and to investigate the width of the energy gap.
The main goal of the presented work was to determine the relationship between changes in the shape of the derivative curve and the microstructure of Zn-Al-Cu alloys before and after modification. To describe the phenomena that occur in the material during solidification as a result of the modification in the chemical composition, the thermal-derivative analysis method was applied. This method allows to describe and interpret the kinetics of crystallisation of the tested alloys. To describe the morphology and phase composition, light and electron microscopy (SEM, TEM) was also used. The modification of the hypereutectic Zn-Al-Cu alloys with the addition of Ce causes a reduction in the size α' + η eutectics and change in the morphology of the α' phase precipitates from dendritic to “tweed”.
Aluminium based metal matrix composite (Al-MMC’s) are much popular in the field like automobile and aerospace industries, because of its ease of fabrication process and excellent mechanical properties. In this study, Al-Zn-Mg alloy composite reinforced with 3, 6 and 9 v % of zircon sand was synthesised by stir casting technique. The microstructure of the composites revealed uniform distribution of reinforced particles. Hardness, tensile strength and wear resistance of Al-Zn-Mg alloy/zircon sand composite were found to increase with increase in v % percentage of zircon sand. Scanning Electron Microscope analysis of wear tested sample surface of composites revealed no evidence of plastic deformation of matrix phase. Particle pulls out and abrasive wear was the common feature observed from all the composites.
The mechanical properties of the commercial synthetic surgical threads (i.e., monofilament MonosynR and polyfilament PolysorbTM) and threads made of pure zinc and selected magnesium alloys were compared. Tensile and relaxation tests of fine fibers/wires without and with a surgical knot were performed on a Zwick 250 tensile machine and on the specially constructed tensile machine dedicated for ultra-thin samples. An about 50% decrease in the maximum tensile load was registered for both synthetic and Mg-based threads due to the presence of a surgical knot while only an about 10% decrease was documented for the zinc threads.
Some eutectic stripes have been generated in a hexagonal (Zn) - single crystal. The stripes are situated periodically with the constant interstripes spacing. The eutectic structure in the stripes consists of strengthening inter-metallic compound, Zn16Ti, and (Zn) – solid solution. The rod-like irregular eutectic structure (with branches) appears at low growth rates. The regular lamellar eutectic structure is observed at middle growth rates. The regular rod-like eutectic structure exists exclusively in the stripes at some elevated growth rates. A new thermodynamic criterion is recommended. It suggests that this eutectic regular structure is the winner in a morphological competition for which the minimum entropy production is lower. A competition between the regular rod-like and the regular lamellar eutectic growth is described by means of the proposed criterion. The formation of branches within irregular eutectic structure is referred to the state of marginal stability. A continuous transitions from the marginal stability to the stationary state are confirmed by the continuous transformations of the irregular eutectic structure into the regular one.
Experimental investigation was conducted on the thermal performance and pressure drop of a convective cooling loop working with ZnO aqueous nanofluids. The loop was used to cool a flat heater connected to an AC autotransformer. Influence of different operating parameters, such as fluid flow rate and mass concentration of nanofluid on surface temperature of heater, pressure drop, friction factor and overall heat transfer coefficient was investigated and briefly discussed. Results of this study showed that, despite a penalty for pressure drop, ZnO/water nanofluid was a promising coolant for cooling the micro-electronic devices and chipsets. It was also found that there is an optimum for concentration of nanofluid so that the heat transfer coefficient is maximum, which was wt. %=0.3 for ZnO/water used in this research. In addition, presence of nanoparticles enhanced the friction factor and pressure drop as well; however, it is not very significant in comparison with those of registered for the base fluid.
Methane (CH4) sensitivity of zinc oxide (ZnO) thin film has been studied in the present work. The sensor element comprises of a chemically fabricated ZnO semiconducting layer and a layer of palladium (Pd) as catalyst. The catalyst layer was formed on the surface of semiconducting ZnO following a wet chemical process from palladium chloride (PdCl2) solution. Fundamental features of a sensor element e.g. sensitivity, response time and recovery process has been studied. The effect of operating temperature on performance of the sensor material has been investigated and a choice of optimum temperature was made at around 200oC. The sensor element exhibited reasonable sensitivity of about 86% at this temperature in presence of 1 vol% methane (CH4) in air.
The ecological meanings clearly indicates the need of reducing of the concentration of the CO2in the atmosphere, which can be accomplished through the lowering of the fuel consumption. This fact implies the research for the new construction solutions regarding the reduction of the weight of vehicles. The reduced weight of the vehicle is also important in the case of application of the alternative propulsion, to extend the lifetime of the batteries with the reduction of recharge cycles. The use of cast alloy AlZnMgCu compliant of plastic forming class 7xxx alloy, are intended to significantly reduce the weight of the structures, while ensuring high strength properties. The wide range of the solidification temperature, which is more than 150°C, characterizes this alloy with a high tendency to create the micro and macro porosity. The study presents the relationship between the cooling rate and the area of occurrence and percentage of microporosity. Then the results were linked to the local tensile strength predicted in the simulation analysis. The evaluation of the microporosity was performed on the basis of the CT (computed tomography) and the analysis of the alloy microstructure. The microstructure analysis was carried out on test specimen obtained from the varying wall thickness of the experimental casting. The evaluation of the mechanical properties was prepared on the basis of the static tensile test and the modified low cycle fatigue test (MLCF).
The main goal of this article is to characterise and compare some aspects of Hilary Putnam’s referential theory of meaning and Robert B. Brandom’s inferential theory of meaning. I will do it to indicate some similarities and differences in these theories. It will provide an opportunity for a deeper understanding of these theories and for a more adequate evaluation of how they describe and explain the process of meaning acquisition of linguistic expressions. In his theory of meaning Putnam emphasises the importance of reference understood as a relationship which connects linguistic expressions and extra-linguistic (empirical) reality. Brandom acknowledges inference as a main category useful in characterising the meaning of expressions used in premises and a conclusion of inference. But his theory of meaning is criticised for minimalising the role of an empirical component (demonstratives etc.). He tries to defend his standpoint in the anaphoric theory of reference. Putnam like Brandom claimed that we – as cognitive subjects – are not in a situation in which we learn about the extra-linguistic reality in a direct way. It is the reality itself as well as our cognitive apparatus that play a role in a cognitive process.
The functioning of European economies and societies requires a stable and sustainable supply of mineral resources. For 10 years now EU has been developing raw materials initiative to secure European minerals supply. In many cases, areas with known or hypothetic mineral resources, are not sufficiently valued by society and authorities, remain unprotected and face competing land uses with the risk of becoming sterilized. MINATURA 2020 project was born out of a need to develop a harmonised framework which allow a common way of identifying “mineral deposits of public importance” (MDoPI) and their safeguarding via land use planning. The project has left a useful set of guidelines and proposals how to advance on the creation of a European network of MDoPIs to avoid sterilization of “deposits worth safeguarding”. In Poland, the need for legal protection of mineral deposits has been discussed intensively in recent years. Various proposals aimed at better system of mineral deposits safeguarding, especially those which should be recognized as of public importance, have been proposed. However, until now only a few coal deposits were recognized as strategic. Currently, the Polish National Mineral Policy is under preparation. Its overriding objective is to provide access to the necessary minerals, also in the longterm perspective. It assumes among others activities aimed at protection of mineral deposits regarding land use planning system. Paper presents scope and general results of MINATURA2020 project, with details on MINATURA2020 methodology implementation in Poland, Project of the Polish National Mineral Policy with its objectives and key pillars, position of MDoPIs in this Project, and – finally – expected future steps related to MDoPI safeguarding in EU and in Poland.
Based on the example of the development process of the cast suspension of a special-purpose vehicle the application of the integrated engineering design methodology (ICME – Integrated Computational Materials Engineering) and the development of construction has been presented. Identification of the operating and critical loads, which are guidelines for carrying out the structure strength shaping process, material and technological conversion, are due to the needs and requirements of the suspension system and the purpose and objectives of the special mobile platform. The developed cast suspension element construction includes the use of high-strength AlZnMgCu aluminum alloy. The properties of the used alloy and designed shape allows for the transfer of assumed operating loads in normal exploitation conditions and in the dynamic, critical loads to the susceptibility to damage in the assumed casting areas. For the proposed design, conducted numerical analyzes includes the impact of the shock wave pulse on the occurrence of the destructive stress fields. Based on their distribution, the areas of possible decomposition of the structure of the design element were estimated. The results allowed to devise an element with predicted destructions that allow to absorb a significant part of the impact energy of the shock wave front, which is also the buffer zone for the propagation of destruction for the critical kinematic nodes of the system.
The aim of this paper is to consider the not so well investigated problem of the role that language has played in Karl Marx’s thinking. The first section discusses several examples of Marxist attempts at philosophical or linguistic reflection on language. I propose the thesis that Marxist meaning theory did not seriously evolve due to the domination of the ‛Traditional Meaning Theory’ (TMT) – irrespective of the actual social conditions. In the second section I undertake some adumbrations on the tendencies of contemporary philosophy of language, such as externalism or pragmatism, whose premonitions can be found in Marx. I also point out that combined with historical materialism they can no longer fit TMT. Finally, I argue that the notion of language and the division of linguistic labor may solve some issues of Marx’s conception of ideology.
A laboratory study was performed to study the effects of various operating factors, viz. adsorbent dose, contact time, solution pH, stirring speed, initial concentration and temperature on the adsorption of triphenyltin chloride (TPT) onto coal fly ash supported nZnO (CFAZ). The adsorption capacity increases with increase in the adsorbent amount, contact time, pH, stirring speed and initial TPT concentration, and decrease with increase in the solution temperature. The adsorption data have been analyzed by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) adsorption models to determine the mechanistic parameters associated with the adsorption process while the kinetic data were analyzed by pseudo first-order, pseudo second-order, Elovich, fractional power and intraparticle diffusivity kinetic models. The thermodynamic parameters of the process were also determined. The results of this study show that 0.5 g of CFAZ was able to remove up to 99.60% of TPT from contaminated natural seawater at 60 min contact time, stirring speed of 200 rpm and at a pH of 8. It was also found that the equilibrium and kinetic data fitted better to Freundlich and pseudo second-order models, respectively. It can therefore be concluded that CFAZ can be effectively used for shipyard process wastewater treatment