It was confirmed that in the north of Poland winged specimens of Myzus persicae (Sulz.) start to migrate in spring approximately over three weeks later than in the central and sou them regions. It was observed that during the 1981-1990 and 1991-2000 decades, M. persicae started its flights approximately over two weeks earlier than during the 1971-1980 decade. With this respect one may conclude that the changes are permanent. There were also changes in quantity. In some places the M. persicae share in the entire aphid fauna on potato crops was observed to have decreased as the time passed, which, as it seems, may be associated with a decrease in potato crops area in Poland. Such a correlation can also be confirmed by the fact that in the area where M. persicae share increased, the potato crops area also increased extensively.

The hillfort Bojná I–Valy is a part of an early medieval fortification system located in the Považský Inovec mountain range that separates two densely populated settlement areas of Slovakia — namely the valleys of the Nitra and Váh rivers. Judging by the abundance of finds, in the 9th century the 12 hectare hillfort was a prominent seat of social elites. A bronze bell, a collection of gilded figural plaques as well as further symbols substantiate Christian affiliation of the community. The core of the monumental ramparts consists of log chambers with inner grates filled with soil and stones. From the front side, it was protected by a stone shell. Pincer gates had inwardly extended arms and a tower entrance in the front part of the corridor. According to the dendrochronological data, the fortification was erected in the last decade of the 9th century and shortly afterwards destroyed by a fire. Excavations of the bottom part of the ramparts confirmed, however, the presence of remains of an older construction. In this area, there are also four further hillforts providing finds dated back to the Early Middle Ages. At least one of them (Bojná II) was also destroyed by a fire at the end of the 9th century or in the 10th century.

This paper presents a study on ferroresonance occurring in a high voltage 400 kV transmission grid due to energization of power transformer under no-load conditions. The system scenarios analyzed in the present paper are considered as critical for development and modernization plans as currently announced by the national grid operator in Poland. The PSCADsimulation modelwas developed and applied for several study cases of a system with double-circuit arrangement of a transmission line. It is shown that the ferroresonant oscillations can be initiated by two-phase switching operation of a line circuit breaker. The impact of the double-circuit length on the ferroresonance mode and severity is demonstrated with the use of the Poincaré map analysis and Short Time Fourier Transform. It is demon- strated that the length of the transmission line that is mutually coupled in the double-circuit arrangement has a significant impact on the ferroresonance occurrence and on its mode. As the ferroresonance can pose severe threat to the power system components due to the severe overvoltage and overcurrent oscillations, the analysis presented in this paper demonstrates the necessity of the ferroresonance analyses for any re-designed transmission system.

This paper presents an analysis of natural vibrations of typical façade scaffolding. Three Finite Element Method models with different levels of accuracy of the real structure of the scaffolding representation were used. Modal analysis was carried out for each of these models. The obtained frequencies and mode shapes were compared with the results from the measurements performed on the full-scale scaffolding. The authors of the paper point out the difficulties arise while modelling such structures, and suggest ways to improve the accuracy of scaffolding computational models.

The paper presents the modelling measurement results of the load-displacement relation for scaffold stands and bracings. In the case of stands, there are two sections of curves, i.e. a straight-line and curvilinear section, and in the case of bracings, two straight line sections as well as one curvilinear section are distinguished. As a result of analyses, it is concluded that the sections which can be approximated by means of linear functions should be distinguished in graphs, if possible. On the one hand, this results from the evaluation methods of scaffold components. Nevertheless, the determination of elastic-linear scope of components’ operation is useful in engineering practice during computer calculations. Moreover, the method of determining an intersection point between functions, approximating tests results, along with analysis of the impact of polynomial degree, approximating the research results, on the time and effectiveness of the process of approximating functions selection, are all demonstrated in this article. The proposed method can prove useful in all science fields where curves obtained from any research (laboratory test, in situ test, numerical analysis) require approximation or replacement with a simpler description.

This paper concerns an approach to model the ledger-stand joints of modular scaffolds. Based on the analysis of the working range of the ledger (represented by a linear relationship between load and displacement), two models of the ledger-stand joint are analysed: first – with flexibility joints and second – with rigid joints and with a transition part of lower stiffness. Parameters are selected based on displacement measurements and numerical analyses of joints, then they are verified. On the basis of performed research, it can be stated that both methods of joint modelling recommended in this paper, can be applied in engineering practices.

Deposits used as fertilizer bring to soil both biogens necessary for plant growth and other ingredients such as metals. including heavy metals. Knowledge of quantities and rate in which heavy metals are to be released to soil from granulates is important because of their toxic influence on plants (in the case of high metals concentration). This paper presents results of investigation of elution of Cu. Zn, Ni, Cd, Pb. and Cr from granulates prepared from municipal sewage sludge, hard coal ash and brown coal ash. Elution to water solution was carried out in static conditions with single-stage and tree-stage extraction. Heavy metal a component of sludge-ash granulates eluted in various quantities, i.e. from trace for cadmium to 9.26-9.53 mg/kg of d.m. for zinc. Among the soluble forms of metals the most mobile are (in decreasing sequence): Cu > Pb> Zn> Ni in granulates containing brown coal ash and Cu> Pb> Ni> Zn in granulates contain hard coal ash.

Short-circuit analysis is conducted based on the nodal impedance matrix, which is the inversion of the nodal admittance matrix. If analysis is conducted for sliding faults, then for each fault location four elements of the nodal admittance matrix are subject to changes and the calculation of the admittance matrix inversion needs to be repeated many times. For large-scale networks such an approach is time consuming and unsatisfactory. This paper proves that for each new fault location a new impedance matrix can be found without recalculation of the matrix inversion. It can be found by a simple extension of the initial nodal impedance matrix calculated once for the input model of the network. This paper derives formulas suitable for such an extension and presents a flowchart of the computational method. Numerical tests performed for a test power system confirm the validity and usefulness of the proposed method.

This paper discusses three variants of how e-mobility development will affect the Polish Power System. Multivariate forecasts of annual new registrations of electric vehicles for up to seven years are developed. The forecasts use the direct trend extrapolation methods, methods based on the deterministic chaos theory, multiple regression models, and the Grey model. The number of electric vehicles in use was determined for 2019‒2025 based on the forecast new registrations. The forecasts were conducted in three variants for the annual electric energy demand in 2019‒2025, using the forecast number of electric vehicles and the forecast annual demand for electric energy excluding e-mobility. Forecasts were conducted in three variants for the daily load profile of power system for winter and summer seasons in the Polish Power system in 2019‒2025 based on three variants of the forecast number of electric vehicles and forecast relative daily load profiles.

In 2014 we finished research works involved in the development of a technology for manufacturing innovative ceramic-carbon foam filters for molten metal alloys filtration, which were financed by the National Centre for Research and Development (NCBiR) from INNOTECH programme resources. A batch of the filters produced in this technology was tested in practice in domestic cast steel and cast iron foundries. The trials were successful and foundries declared their intention to purchase the newly-developed filters for the current production of casts. This provided an incentive for “Ferro-Term” Sp. z o.o. to start design works on the prototype line for a serial production of these filters. At the same time, in co-operation with a scientific consortium, including the co-authors of the technology, i.e. the Institute of Ceramics and Building Materials, Refractory Materials Division in Gliwice, Institute for the Chemical Processing of Coal in Zabrze and Foundry Research Institute in Cracow, the company made a successful attempt to raise some funds for the necessary adaptation of the developed technology from the semi-technical to industrial scale from Intelligent Development Operational Programme. In the article we have presented information on the effects of works performed within the framework of the project entitled “Modernization and adaptation of the existing technological line for purposes related to technology verification and start-up of the production of innovative ceramic-carbon filters for molten metal alloy filtration”.