This work concerns the experimental verification of changes in the energy efficiency of photovoltaic installations through the use of bifacial modules. For this purpose, an experimental stand was designed and built for the comparative analysis of the efficiency of two types of photovoltaic panels: bifacial (bPV) and monofacial (mPV). The tests consisted of placing the panels at different heights above the ground surface and at different angles. During the tests, three substrates with different albedo were taken into account: green grass, gray concrete (fabric), and white snow (polystyrene). The tests for both types of panels were carried out simultaneously (in parallel), which guaranteed the same environmental conditions (temperature and solar radiation intensity). Based on the results of the voltage and current measurements for different angles of PV module inclination and, for bPV panels, different heights above the ground surface and different types of substrate, a series of current–voltage characteristics and power characteristics were plotted. The “additional” energy efficiency of bifacial panels compared to monofacial panels was also determined. It was shown that under favorable conditions, using bifacial panels instead of monofacial panels can increase the production of electricity by more than 56% from structures of the same dimensions. The research results can be of great value when designing photovoltaic installations.

The production of high-quality nonwovens, composed of polyester and viscose, depends to a large extent on the carding process of both components. Due to the complexity of the operations carried out, in the mixing, unifying and stretching of the raw materials, this process is one of the most important and is carried out on machines called carding machines. Today, carding machines are manufactured by many manufacturers and their complexity is increasing. In this article, two modern carding machines, consisting of two main drums coupled to five carding-doffer assemblies, but differing in the transmission of the fibre deck between the main drums and the mechanical performance of the operation, were submitted for comparative analysis. To this end, mathematical models of the carding process were developed and the stabilisation and delay times of the fibres in the carding process were determined; the absorption coefficients between each pair of co-working drum pairs in the carding analyses were also determined. On this basis, numerical simulations were conducted and are presented and discussed here.

This article describes the studies of the mechanical properties of the martensitic structure of C45 steel, obtained as a result of heat treatment. This steel was subjected to high tempering, within the temperature range of 500 ÷ 700°C (every 50°C) and for various exposure times, from 15...

The production of nonwoven fabric dedicated to the hygiene sector of industry is a dynamically developing market segment. Competition among manufacturers forces high performance in the economic production of nonwoven fabric with appropriate physical–mechanical parameters. One of the most important processes which guarantees that such characteristics may be obtained in the production of nonwoven fabrics, is the carding process. The article presents the modelling of the carding process on a modern, double-drum carder. The dynamics of the formation of nonwoven slivers was analysed, taking into account the homogeneity of the density of the fleece formed. In the description of carding dynamics, the mass balance of fibres was taken into account. Numerical simulations concerning the gradual increase in fibre accumulation, over time – and in relation to the fibre collection factor and the number of rollers in the worker–stripper systems – are presented.

The production of Spunlace nonwoven fabric is a complex process and includes, among other things, several important stages, such as carding, needling and drying. One of the most important stages is the carding process, which has a significant impact on the shaping of the physico-mechanical and qualitative characteristics of the nonwoven fabric. The article presents the modelling of the carding process in a two-drum system. A mathematical model, determining the expected number of drum and carding card cycles was proposed. Based on this model, delays were determined, due to longitudinal shifts of fibre in the carding process. Numerical simulations have been made and discussed in relation to fibre collection factors, at different production speeds and the number of carding rollers in the worker-stripper system.