Czy w Tatrach były lodowce? Jeśli tak, to jak podczas zlodowacenia wyglądały te góry? Może przypominały współczesne Alpy? Na cofnięcie się w czasie o ponad 20 tys. lat i znalezienie odpowiedzi na te pytania pozwala pierwsza paleogeograficzna mapa Tatr 3D.

Niewystarczająca moc obliczeniowa do przetworzenia danych? Absurdalna liczba roboczogodzin konieczna do inspekcji surowych wyników? Naukowcom, którzy mają tego typu problemy, mogą przyjść z pomocą wolontariusze wyposażeni jedynie w komputer podłączony do sieci. Czyli prawie wszyscy.

W Międzynarodowym Roku Światła dr Bogdan Wszołek otworzył prywatne obserwatorium astronomiczne w Rzepienniku Biskupim. Dla nas pisze o tym, jak spełniło się jego marzenie i jaką przyszłość sobie zaplanował.

O tym, jak działają szczepionki i dlaczego ich stosowanie jest ważne, rozmawiamy z prof. zw. dr hab. Lidią B. Brydak, kierownikiem Zakładu Badania Wirusów Grypy i Krajowego Ośrodka ds. Grypy, oraz dr n. med. Iwoną Paradowską-Stankiewicz, konsultantem krajowym ds. epidemiologii.

Prawie 13% wszystkich gatunków ptaków oraz 95% związanych ze środowiskiem morskim gniazduje w koloniach. Wiąże się z tym szereg zachowań socjalnych, które można interpretować jako współpracę.

Kiedy w XVII wieku w Europie zapanowała moda na muzykę włoskim, śpiewacy i instrumentaliści z Italii ruszyli za Alpy, przez możnych mecenasów. Dotarli też do Polski, wspierając kapele dworskie i magnackie.

Lokalizacja miejsc prehistorycznego wydobycia rud miedzi oraz procesów produkcji przedmiotów metalowych jest kluczem do odpowiedzi na pytania dotyczące przełomowych momentów w cywilizacyjnym rozwoju Europy. Multidyscyplinarny zespół składający się z archeologów, geologów i inżynierów materiałowych przystąpił do wypracowania uniwersalnej metodologii badawczej.

Jaki wpływ na środowisko wywarły średniowieczne armie, toczące święte wojny przeciwko poganom zamieszkującym wschodnie wybrzeża Bałtyku? Odpowiedzi na to pytanie poszukiwał międzynarodowy zespół badawczy w projekcie „Krucjaty a ekologia".

Scaffolding is equipment usually used at construction sites. A scaffolding structure is lightweight and made of elements used many times. The characteristics of scaffolding make it susceptible to dynamic actions present at the structure or occurring nearby. A scaffolding structure of medium size was subjected to analysis in this paper. The structure FEM model was loaded with single force harmonic excitation with various frequencies ranging from 1 Hz to 12 Hz applied in one of many selected points on the scaffolding façade. In the first step, natural frequencies and mode shapes of the analyzed structure were calculated. Then the full dynamic analysis was carried out to obtain maximum displacements of selected control points. The relation of excitation force frequency and location to the amplitudes of generated displacement was observed. It was found that low excitation frequencies close to the natural frequencies of the structure produced vibrations ranging to large areas of the scaffolding surface. Higher excitation frequencies are usually less propagated at the scaffolding but still may produce some discomfort to the structure users in the vicinity of the excitation force location. Scaffolding is equipment usually used at construction sites. A scaffolding structure is lightweight and made of elements used many times. The characteristics of scaffolding make it susceptible to dynamic actions present at the structure or occurring nearby. A scaffolding structure of medium size was subjected to analysis in this paper. The structure FEM model was loaded with single force harmonic excitation with various frequencies ranging from 1 Hz to 12 Hz applied in one of many selected points on the scaffolding façade. In the first step, natural frequencies and mode shapes of the analyzed structure were calculated. Then the full dynamic analysis was carried out to obtain maximum displacements of selected control points. The relation of excitation force frequency and location to the amplitudes of generated displacement was observed. It was found that low excitation frequencies close to the natural frequencies of the structure produced vibrations ranging to large areas of the scaffolding surface. Higher excitation frequencies are usually less propagated at the scaffolding but still may produce some discomfort to the structure users in the vicinity of the excitation force location.

The paper presents a novel hybrid cuckoo search (CS) algorithm for the optimization of the line-start permanent magnet synchronous motor (LSPMSM). The hybrid optimization algorithm developed is a merger of the heuristic algorithm with the deterministic Hooke–Jeeves method. The hybrid optimization procedure developed was tested on analytical benchmark functions and the results were compared with the classical cuckoo search algorithm, genetic algorithm, particle swarm algorithm and bat algorithm. The optimization script containing a hybrid algorithm was developed in Delphi Tiburón. The results presented show that the modified method is characterized by better accuracy. The optimization procedure developed is related to a mathematical model of the LSPMSM. The multi-objective compromise function was applied as an optimality criterion. Selected results were presented and discussed.

The paper presents arch structures modeled by finite elements in which the nodes can be flexibly connected. Two-node curved elements with three degrees of freedom at each node were used. Exact shape functions were adopted to obtain stiffness and consistent mass matrices but they were modified by introducing rotational flexibility in the boundary nodes. Calculations of statics and dynamics of arches with different positions of flexible joints and different values of rotational stiffness of the joints were carried out.

The paper demonstrates the potential of wavelet transform in a discrete form for structural damage localization. The efficiency of the method is tested through a series of numerical examples, where the real flat truss girder is simulated by a parameterized finite element model. The welded joints are introduced into the girder and classic code loads are applied. The static vertical deflections and rotation angles of steel truss structure are taken into consideration, structural response signals are computed at discrete points uniformly distributed along the upper or lower chord. Signal decomposition is performed according to the Mallat pyramid algorithm. The performed analyses proved that the application of DWT to decompose structural response signals is very effective in determining the location of the defect. Evident disturbances of the transformed signals, including high peaks, are expected as an indicator of the defect existence in the structure. The authors succeeded for the first time in the detection of breaking the weld in the truss node as well as proved that the defect can be located in the diagonals.

The analyses aim to determine aerodynamic force coefficients in the case of airflow around two smooth or rough cylinders positioned at different angles to the direction of wind velocity. Such systems, for instance, may be part of a tubular water slide. The results were compared with the values of the interference coefficient of the cylinders arranged in a row included in Eurocode EN 1991 part 4. The aerodynamic forces of the cylinder systems were determined on the basis of experimental tests conducted in a wind tunnel. To verify the above results, CFD (computational fluid dynamics) simulations were prepared. An important observation is that for the angle of yaw β = 0◦, the negative component of the lift force (lateral) fy is shown, while for the other cases, the situation is opposite and the lateral force points outside the gap (upward). The second is that the results of aerodynamic drag for rough cylinders arranged in a row and calculated according to EN 1991 part 4 may be underestimated. The flow around the pair of smooth cylinders is quite different from that of the rough ones, because during the experiment the first falls into the critical flow regime, while the second has supercritical characteristics.

“Polyurea coatings as a possible structural reinforcement system” is a research project aimed at exploring possible applications of polyurea coatings for improving structural performance (including steel, concrete, wooden and other structures used in the construction industry). As part of the project, this paper focuses on evaluating the performance of bent reinforced concrete (RC) beams covered with a polyurea coating system. Easy polyurea application and its numerous advantages can prove very useful when existing RC structural elements are repaired or retrofitted. Laboratory tests of three types of RC beams with three different longitudinal reinforcement ratios were performed for the purposes of this paper. The tests were designed to determine the bending strength, performance and cracking patterns of the coated RC beams. In addition, a theoretical model was developed to predict the impact of the polyurea coating on the bending strength of the RC beams. On this basis, the effect of the coating on the bending strength and the performance of the coated beams at the ultimate limit state (ULS) was examined and analyzed. The results showed that the use of the polyurea coating has a positive impact on the cracking state of the RC beams subject to bending and little effect on their bending strength.

The calculations of fuel tanks should take into account the geometric imperfections of the structure as well as the variability of the material parameters of the foundation. The deformation of the tank shell can have a significant impact on the limit state of the structure and its operating conditions. The paper presents a probabilistic analysis of a vertical-axis, floating-roof cylindrical shell of a tank with a capacity of 50000 m3 placed on stratified soil with heterogeneous material parameters. The impact of a random subsoil description was estimated using the Point Estimated Method (PEM). In this way, the number of analyzed FEM models was significantly reduced. This approach also makes it possible to assess the sensitivity of tank settlement and deformation to the changing foundation conditions.