Projekt optymalnego przekroju cienkościennego dwuteownika przy zadanych więzach naprężeniowych

This paper deals with the problem of optimization of a thin-walled open section I-beam loaded in a complex way, subjected to the bending, torsion and constrained torsion. A general case of bending moments about two centroidal axes, the torsion and the bimoment acting simultaneously, is derived and then some particular loading cases are considered. The problem is reduced to the determination of minimum mass, i.e. minimum cross-sectional area of structural thin-walled beam elements of the chosen shape for the given complex loads, material and geometrical characteristics. The optimization parameters have been determined by Lagrange’s multipliers method. The area of the cross-section has been selected as the objective function. The stress constraint is introduced and used as the constraint function. The obtained results are used for numerical calculation.Wpracy zajęto się zagadnieniem optymalizacji cienkościennej belki o otwartym przekroju dwuteowym poddanej złożonemu stanowi obciążenia, tj. zginaniu i skręcaniu przy narzuconym warunku na naprężenia ścinające. Rozważono ogólny przypadek momentów gnących działających względem osi centralnych przekroju przy jednoczesnym obciążeniu skręcaniem oraz bimomentem, a następnie przedyskutowano przypadki szczególne. Problem optymalizacji zredukowano do zadania minimalizacji masy przekroju belki dla zadanego kształtu, charakterystyk materiałowych oraz rodzaju obciążenia. Parametry optymalizacji wyznaczono metodą mnożników Lagrange’a. Na funkcję celu wybrano pole przekroju dwuteownika. Do opisu brzegu obszaru optymalizacji użyto funkcji więzów stanu naprężenia. Otrzymane wyniki posłużyły za podstawę do przeprowadzenia symulacji numerycznych

Cold War Football: Soviet Defence and Yugoslav Attack following the Tito-Stalin Split of 1948

This essay explores the symbolic role played by football in the Tito-Stalin Split (1948-1953). In particular, it looks at the Yugoslav national team’s victory over the Soviet Union at the 1952 Olympics in Finland. It asks how Yugoslav sports administrators, athletes and the press negotiated the transition from a position of affectionate sporting emulation of the USSR, to one of hostile opposition. Both regimes paid close attention to international sporting competition and its potential propaganda benefits. Shedding light on an early intra-socialist rupture, this case deserves to be considered alongside better known instances of sporting conflict in the Cold War

Glass production in the Middle Ages from Italy to Central Europe: the contribution of archaeometry to the history of technology

The present paper reports and discusses data obtained by a combined archaeological and archaeometric study carried out on an assemblage of selected Medieval glass finds from the Monastery of St. Severus in Classe (Ravenna, Italy) and ascribable to the 13–16th CE. Glassware belonging to three main typological groups was selected for this study: ampoules, nuppenbecher and kropfflasche. Such a choice mainly stems from the intent to evaluate typological and compositional affinities of these peculiar vessel typologies with the same forms unearthed in different regions of Central Europe, as a starting point for a possible reconstruction of trade contacts between Italy and Central Europe. Archaeological contextualisation of the site and chrono-typological study of glass vessels were associated to ICP-MS (inductively coupled plasma mass spectrometry) and ICP-OES (inductively coupled plasma optical emission spectrometry) analyses, performed to characterise the composition of the glassy matrix (major and minor components as well as trace elements). The results, elaborated according to the archaeometric glass classification and provenancing of raw materials, shed new light on glass production in late Medieval times and can be broaden framed as a starting point for interpreting relations and exchanges between geographical areas and related cultures