Riassunto Lo studio sottolinea che fin dalla sua fondazione, nel 1452, da parte del predicatore italiano Giovanni di Capestrano, il vicariato francescano dell’Osservatorio „Boemia“ – il quale ...abbracciava tutte le terre della corona boema, l’Austria, la Stiria e in seguito la Polonia – era caratterizzato da una grande diversità etnica e linguistica. In particolare, l’autore esamina le dispute tra italiani e tedeschi nel capitolo provinciale di Brno (1456), il conflitto polacco-tedesco (1460–1467) e le polemiche tra cechi e tedeschi che raggiunsero l’apice nel 1490, durante il capitolo generale francescano svoltosi in quell’anno a Urbino.
The process of alkali activation of fly ash and metakaolin is examined in the view of micromechanics. Elasticity is predicted via semi-analytical homogenization methods, using a combination of ...intrinsic elastic properties obtained from nanoindentation, evolving volume fractions and percolation theory. A new quantitative model for volume fraction is formulated, distinguishing the evolution of unreacted aluminosilicate material, solid gel particles of N-A-S-H gel, and open porosity, which is partially filled with the activator. The stiffening of N-A-S-H gel is modeled by increasing the fraction of solid gel particles. Their packing density and intrinsic elasticity differ in N-A-S-H gels synthesized from both activated materials. Percolation theory helps to address the quasi-solid transition at early ages and explains a long setting time and the beneficial effect of thermal curing. The low ability of N-A-S-H gel to bind water chemically explains the high porosity of Ca-deficient activated materials. Micromechanical analysis matches well the elastic experimental data during the activation and elucidates important stages in the formation of the microstructure.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The presented research aims to clarify the specific effect of the individual components of concrete with Portland cement CEM I 42.5 R on the volume changes of concrete. The effect of the filler ...component was evaluated from the point of view of the composition and type of aggregate (crushed versus mined) and from the point of view of the mineralogical composition of the aggregate. Concrete formulas with a maximum aggregate grain size of 16 and 22 mm were assessed. The effect of the binder component on the shrinkage of the concrete was monitored on the concrete mixtures produced using the same aggregate and maintaining the same strength class of concrete, C 45/55. The effect of the addition of finely ground limestone, finely ground granulated blast furnace slag and coal high-temperature fly ash was monitored. It was found that the maximum aggregate grain and the type of grading curve do not have a significant effect on the volume changes of concrete. Concretes with mined aggregates showed lower shrinkage than concretes with crushed aggregates. The most significant is the effect of the type of aggregate on the volume changes in the first 24 h. Mineral additives have a positive effect on the elimination of the volume changes of concrete, while the addition of high-temperature fly ash proved to be the most suitable.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The present work addresses powder bed binder jetting additive manufacturing by selective magnesium phosphate cement activation. Despite the potential of this technology to aid the digitalization of ...the construction industry, the effect of processing parameters on the mechanical performance of printed materials has not yet been studied to generate a guideline for the further development of the technology. Statistical methodologies were used to screen the effect of four printing process parameters (printing speed, layer thickness, raster angle, and build direction on flexural and compressive strength). As the exploited technology works with constant fluid pressure, the physical interpretation of the effect of each factor can be considered taking into account the interactions between the binder materials in the powder bed. Analysis of variance (ANOVA) indicated that printing speed and layer thickness significantly affect mechanical performances. Furthermore, the layout of samples for the printing process is preferable to be parallel the printhead movement. An anisotropic behavior was observed, and the samples subjected to compressive forces parallel to the layer plane possessed lower strength values. This effect can be interpreted as a result of a weak area of low density in between layers, leading to a pronounced delamination under compression.
Even though the strength of the printed material is not suitable for a structural concrete, it can be marginally improved by design of experiment and optimized for non-structural applications, such as for porous artificial stone. Design of experiment coupled with ANOVA methods can be used in the future to support the development of novel material mixtures, thus expanding the fields of application of this novel additive manufacturing technology.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The development of alkali-activated materials (AAMs) as an alternative to Portland cement (PC) has seen significant progress in the past decades. However, there still remains significant uncertainty ...regarding their long term performance when used in steel-reinforced structures. The durability of AAMs in such applications depends strongly on the corrosion behaviour of the embedded steel reinforcement, and the experimental data in the literature are limited and in some cases inconsistent. This letter elucidates the role of the chemistry of AAMs on the mechanisms governing passivation and chloride-induced corrosion of the steel reinforcement, to bring a better understanding of the durability of AAM structures exposed to chloride. The corrosion of the steel reinforcement in AAMs differs significantly from observations in PC; the onset of pitting (or the chloride ‘threshold’ value) depends strongly on the alkalinity, and the redox environment, of these binders. Classifications or standards used to assess the severity of steel corrosion in PC appear not to be directly applicable to AAMs due to important differences in pore solution chemistry and phase assemblage.
Celem pracy jest identyfikacja grup krajów Unii Europejskiej podobnych co do struktury zatrudnienia w ujęciu dynamicznym, z wykorzystaniem metody aglomeracyjnej najdalszego sąsiedztwa.W ocenie ...wykorzystano informacje o zatrudnieniu w krajach Unii Europejskiej, dokumentowane m.in. w podziale na 10 sekcji: rolnictwo, przemysł, budownictwo, handel, informacja, finanse i ubezpieczenia, nieruchomości, usługi profesjonalne, sfera budżetowa, kultura. Analizowane są podobieństwa struktur zatrudnienia w krajach Unii Europejskiej w latach 2008–2017. Dla każdego roku osobno wyznaczono macierz odległości (niepodobieństwa) struktur zatrudnienia pomiędzy krajami UE. Wykorzystując tę macierz, zastosowano taksonomiczną metodę aglomeracyjną najdalszego sąsiedztwa, która po metodzie Warda jest drugą co do skuteczności metodą odkrywania grup podobnych w zbiorach analizowanych obiektów. Wybór metody zdeterminowany był wykorzystaną miarą odległości, jak również jej elastycznością – na podstawie analizy porównawczej uzyskanych dendrogramów – poziomu cięcia dendrogramu. W pracy, po obserwacji otrzymanych drzew klasyfikacyjnych, przyjęto odległość krytyczną jako 0,15. Oznacza to, że dwie grupy obiektów mogą być połączone, jeżeli najdłuższa odległość pomiędzy obiektami należącymi do różnych podgrup nie przekracza 0,15. Przy cięciu dendrogramu na poziomie 0,15 otrzymano dla każdego roku podział krajów UE na grupy zbliżone co do struktury zatrudnienia. Okazało się, że Luksemburg oraz Rumunia we wszystkich latach stanowiły osobne, jednoelementowe grupy. Dla pozostałych krajów wyróżniono trzy zasadnicze grupy.Poddano analizie zmiany składu grup w czasie oraz dynamikę średnich struktur dla grup.
The article focuses on mapping the innovation potential of the regions in Czech Republic, Slovakia, and Poland having their own elected institutions, which may influence the development of innovation ...potential of the regions. The correlation analysis and calculation of the aggregate index were used for comparison of the regions. The research is based on the authors’ own construction of the Innovation Potential Index which uses 6 indicators: a) GDP per capita in EUR, b) the share of inhabitants with university degree in population, c) the share of R&D involved persons per workforce, d) gross fixed capital formation (GFCF) by regions, e) the number of patents and utility models per regions. Better conditions for growing innovation potential can be seen in the metropolitan areas rather than in agricultural and old industrial regions. The main advantage of old industrial regions is that they can improve their innovative potential by transforming the economic potential, which is weak in the peripheral and agrarian regions.
This paper explores the process of achieving sustainable development at a regional level in post-socialist states in the context of the clusters concept. In spite of the research on how it is ...achieved in particular countries, it remains under-researched or the results are in conflict. We consider if qualitative parameters of regions, the complex process of dependence between R&D financing in regions, whether the policies implemented in the development processes of post-socialist countries are important for the greater development of clustering and the higher concentration of clusters. The empirical analysis is based on Spearman's ρ rank correlation and the stepwise regression analysis. We find that dependencies between the functioning of clusters and selected factors of the sustainable and qualitative development of regions were confirmed. The research shows that the expected effects are not clear, albeit that such policies resulted in a change in the direction of the activities, and that better performance can be expected by taking directional measures. Overall, our findings confirm the expected dependencies of involving public financing on R&D and clusters in regions. We find that the policies implemented in the post-socialist states do not necessarily involve large-scale permanent environmental improvement.
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