GNSS systems are susceptible to radio interference despite then operating in a spread spectrum. The commerce jammers power up to 2 watts that can block the receiver function at a distance of up to 15 kilometers in free space. Two original methods for GNSS receiver testing were developed. The first method is based on the usage of a GNSS simulator for generation of the satellite signals and a vector signal RF generator for generating different types of interference signals. The second software radio method is based on a software GNSS simulator and a signal processing in Matlab. The receivers were tested for narrowband CW interference, FM modulated signal and chirp jamming signals and scenarios. The signal to noise ratio usually drops down to 27 dBc-Hz while the jamming to signal ratio is different for different types of interference. The chirp signal is very effective. The jammer signal is well propagated in free space while in the real mobile urban and suburban environment it is usually strongly attenuated.

The presented results of investigations are part of a larger study focused on the optimization of the flow and mixing of liquid steel in the industrial tundish of continuous casting machine. The numerical simulations were carried out concern the analysis of hydrodynamic conditions of liquid steel flow in a tundish operating in one of the national steelworks. Numerical simulations were performed using the commercial code ANSYS Fluent. The research concerns two different speeds of steel casting. In real conditions, these speeds are the most commonly used in the technological process when casting two different groups of steel. As a result of computational fluid dynamics (CFD) calculations, predicted spatial distributions of velocity and liquid steel turbulence fields and residence time distribution (RTD) curves were obtained. The volume fractions of different flows occurring in the tundish were also calculated. The results of the research allowed a detailed analysis of the influence of casting speed on the formation of hydrodynamic conditions prevailing in the reactor.

The results of studies presented in this article are an example of the research activity of the authors related to lead-free alloys. The studies covered binary SnZn90 and SnZn95 lead-free alloys, including their microstructure and complex mechanical characteristics. The microstructure was examined by both light microscopy (LM) and scanning electron microscopy (SEM). The identification of alloy chemical composition in micro-areas was performed by SEM/EDS method. As regards light microscopy, the assessment was of both qualitative and quantitative character. The determination of the geometrical parameters of microstructure was based on an original combinatorial method using phase quantum theory. Comprehensive characterization of mechanical behavior with a focus on fatigue life of alloys was performed by means of the original modified low cycle fatigue method (MLCF) adapted to the actually available test machine. The article discusses the fatigue life of binary SnZn90 and SnZn95 alloys in terms of their microstructure. Additionally, the benefits resulting from the use of the combinatorial method in microstructure examinations and MLCF test in the quick estimation of several mechanical parameters have been underlined.

The paper presents the results of the computer simulations of solidification with consideration of the liquid phase movement. Simulations were conducted in a real, complex cast. There is a multi-stage resolution to the problem of convection in solidification simulations. The most important resolution concerns the development of the numerical model with the momentum and continuity equations, as well as conditions which are determined by the convection. Simulations were carried out with the use of our authorial software based on stabilized finite elements method (Petroy-Galerkin). In order to solve Navier-Stokes equation (with the convection element), Boussinesq’s approximation were used. Finite Elements Method (FEM) was responsible for the solidification. FEM is close to the heat conduction equation solution (with the internal heat source responsible for the heat released during phase transformation). Convection causes movement in the liquid phase in the solidifying cast and can significantly influence the process of heat transfer from the cast. It may change the distribution of the defects. Results of this article make it possible to assess the conditions in which the influence of the convection on solidification is significant.

The results presented here are twofold. First, a heuristic algorithm is proposed which, through removing some unnecessary arcs from a digraph, tends to reduce it into an adjoint and thus simplifies the search for a Hamiltonian cycle. Second, a heuristic algorithm for DNA sequence assembly is proposed, which uses a graph model of the problem instance, and incorporates two independent procedures of reducing the set of arcs - one of them being the former algorithm. Finally, results of tests of the assembly algorithm on parts of chromosome arm 2R of Drosophila melanogaster are presented.

The article herein presents a new technique of controlling the system of collecting, storing and processing the information from the solar collectors, which might be applied to heating the industrial and domestic compartments for hot water supply. The most profitable usage of the solar collectors in the industry is replacement of a human interference with wireless sensor nets. The solar collector standard system consumes in average 30% of the heat due to poor control and configuration. Our monitoring and control system allows upgrade the performance of heating the industrial and domestic premises by means of solar collector for hot water supply.

This article presents a study of the crystallization and microstructure of the AlSi9 alloy (EN AC-AlSi9) used for the alfin processing of iron ring supports in castings of silumin pistons. Alfin processing in brief is based on submerging an iron casting in an Al-Si bath, maintaining it there for a defined time period, placing it in a chill mould casting machine and immersing it in the alloy. This technology is used for iron ring supports in the pistons of internal combustion engines, among others. Thermal analysis shows that when the AlSi9 alloy contains a minimal content of iron, nucleation and increase in the triple (Al)+Fe+(Si) eutectic containing the -Al8Fe2Si phase takes place at the end of the crystallization of the double (Al)+(Si) eutectic. Due to the morphology of the ”Chinese script” the -Al8Fe2Si phase is beneficial and does not reduce the alloy’s brittleness. After approx. 5 hours of alfin processing, the -Al5FeSi phase crystallizes as a component of the +Al5FeSi+(Si) eutectic. Its disadvantageous morphology is ”platelike” with sharp corners, and in a microsection of the surface, ”needles” with pointed corners are visible, with increases the fragility of the AlSi9 alloys.

The implementation of the sustainable development objectives, requires additional knowledge about underwater landscapes of inland reservoirs. In this article, we assumed that (1) underwater landscapes of lakes are shaped mainly by the type of substrate and the assemblages of flora and fauna inhabiting a given reservoir; (2) vegetation is one of the most important elements of underwater landscapes, which dynamically reacts to environmental changes. This article presents the results of a study on the underwater landscapes of Lake Wielki Staw in the Karkonosze Mountains. Thirteen types of underwater landscapes were distinguished in the lake based on underwater inventory and spatial analysis using ArcGIS 10.7 software. The level of changes that occurred in the underwater landscape studied was determined using the underwater landscape structure maps for 2005, 2011, 2017, and 2021. In addition, the landscape change index ( LCI) for Lake Wielki Staw was determined for 2005–2011, 2011–2017, and 2017–2021. The results obtained indicate that underwater landscapes in lakes, similarly to terrestrial landscapes, are dynamic and subject to changes. In the case of Lake Wielki Staw, the changes in the range of Isoëtes lacustris communities in individual parts of the lake limited the differences in the area of all types of underwater landscapes distinguished. This allows us to use underwater vegetation inhabiting a given reservoir as an indicator of changes in underwater landscapes. Keywords:

Rhizoctonia solani was isolated from 91 % of alder and birch seedlings with stem rot symptoms and 2-3% of seeds. Sowing of seeds to substratum infested with R. solani resulted in pre-and postemergence damping off. On leaves and stem parts of alder and birch, inoculated with 3 isolates of R. solani, necrosis spread from 0.22 to 0.52 mm/hr.