Biogas plants are one of the most stable sources of renewable energy. Currently, there is a noticeable increase in the amount of post-production residues from agricultural production and agri-food processing (fruit and vegetable processing, fermentation, beet pulp, or lignocellulosic waste), which, can be used for biogas production after appropriate pretreatment. The aim of this study was to examine the possibility of using the biomass produced during the cultivation of grapes on a selected farm as a substrate for a biogas plant, taking into account the production process. The research was carried out in 2018–2020 in a vineyard located in the Sandomierz Upland in the south-eastern part of Poland. Own rooted vines were grown as a single continuous string with a trunk height of 40 cm and a length of one fixed arm approx. 0.9 m, on which six pivots were left every year after applying a short cut, from which 12–16 fruit shoots were derived, the so-called grapevines. Leaves were collected at random from three locations on the fruiting shoot, a total of 30 leaves in each replicate. Each sample consisted of 1/3 of the leaves collected at the bottom, 1/3 in the middle, and 1/3 at the top of the canopy. Leaf area was estimated with a model 3100 area meter on a sample of 30 leaves from each replicate. Both the quantity and quality of the obtained material as a substrate for methane fermentation were evaluated. Biogas yield tests in optimal conditions for mesophilic bacteria were conducted on three substrate samples referred to as ‘Regent’, ‘Seyval Blanc’, and ‘Solaris’. The yields of the tested material ranged from 51.0 to 59.0 Nm ³ biogas per Mg of biomass.

This paper concerns the possibility of use the Jiles-Atherton extended model to describe the magnetic characteristics of construction steel St3 under mechanical stress. Results of the modelling utilizing extended Jiles-Atherton model are consistent with results of experimental measurements for magnetic hysteresis loops B(H). Material stress state determination by using non-destructive, magnetic properties based on testing techniques is an especially important problem.

This paper aims to present a new equivalent scheme of multi-windings traction transformers, based on multiport purely inductive circuit. The mathematical background of this equivalent scheme is described. The determination of the different scheme elements is made through a finite-elements calculation of both main and leakage inductances, for the case of a four-winding transformer. A procedure is defined, which allows to estimate the values of these elements from some measurements on the transformer at no-load and short-circuit operations. A specific strategy of short-circuit tests is described, allowing to determine all parameters in a rather simple way.

The article La Rilettura del romanzo Il fu Mattia Pascal di Luigi Pirandello nell’otica del racconto cinematografico di Mario Monicelli, presents an individual story of Mattia Pascal and his reincarnations in Adriano Meis and the late Mattia Pascal. It concentrates on the journey of the main character, in the original dimension of time and space, in search of a new, happy life and of his identity. In reference to the subject matter included here, various different theories are applied to the cinematic analysis of the ‘new’ work of Pirandello.