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This paper focused on the investigation of the blades for a carousel rotor of a wind turbine with a vertical axis. Cross sections of the single coherent (SC) and the dual coherent (DC) blades were compared in terms of the aerodynamic forces and aerodynamic torque generated during rotor operation for various wind attack angles. The design of the DC blade is novelty proposed by the authors. The main objective of the study was to determine the influence of the blade cross-section on the propelling torque of a wind turbine with three blades, which is an important parameter for rotor starting. First, experimental studies were carried out in a wind tunnel for real-size blade models. A CFD analysis of the airflow around the blades was then conducted. The obtained results were used to evaluate the suitability of applying the studied blade types in the design of the carousel wind rotor. The assessment compared the drag force and the lift force as well as aerodynamic torque as a function of a wind attack angle. It was concluded that the rotor with three DC blades involved mainly the drag force in contrast to the rotor with three SC blades that also involved the lift force to a greater extent. Despite the rotor with DC blades obtained greater values of the drag forces on the blades, the rotor with SC blades obtained a greater starting torque.

This paper examines the energy efficiency of three variations of the two-degree-of-freedom transverse galloping energy harvester. These variants differ in the number and placement of electromechanical transducers. By utilizing the harmonic balance method, the limit cycles of mathematical models of the devices were determined. Analytical expressions derived from the models were then used to formulate the efficiency of the systems. It was demonstrated that efficiency depends on flow speed and can be comprehensively characterized by the following criteria parameters: peak efficiency, denoting the maximum efficiency of the system, and high-efficiency bandwidth, which describes the range of flow speeds within which the efficiency remains at no less than 90% of peak efficiency. The values of these parameters are heavily reliant on two other parameters: the speed at which the system achieves peak efficiency, referred to as the nominal speed, and also the flow speed at which the system undergoes Hopf bifurcation, namely the critical speed. Comparative analysis revealed that only the device equipped with two electromechanical transducers can potentially outperform a simple one-degree-of-freedom system. For selected parameters, this gain reached nearly 10%.

In recent years, significant progress has been achieved in developing the potential of anaerobic membrane bioreactors (AnMBRs). The present paper presents a comprehensive review of studies focused on biogas production via the treatment of municipal and domestic wastewater with the use of such technology. The main aim of the current work was to evaluate the impact of operating parameters on the biogas production yield. Moreover, the possibilities of applying various fouling mitigation strategies have been discussed in detail. Analyses have been performed and reported in the literature, which were conducted with the use of submerged and external AnMBRs equipped with both polymeric and ceramic membranes. It has been shown that, so far, the impact of the hydraulic retention time (HRT) on biogas yield is ambiguous. This finding indicates that future studies on this issue are required. In addition, it was demonstrated that temperature has a positive impact on process performance. However, as presented in the literature, investigations have been carried out mainly under psychrophilic and mesophilic conditions. Hence, performing further experimental studies at temperatures above 40 °C is highly recommended. Moreover, it has been shown that in order to restore the initial permeate flux, a combination of several membrane cleaning methods is often required. The findings presented in the current study may be particularly important for the determination of operating conditions and suitable fouling mitigation strategies for laboratory-scale and pilot-scale AnMBRs used for biogas production via the treatment of municipal and domestic conditions.

The advancement of laser ultrasonics has increased rapidly in recent years, providing applications for materials characterization as well as for industrial utilization, as a quality control device. The wide-ranging capabilities for high-temperature in-situ analysis of a variety of microstructural characteristics offers a multitude of possibilities for usage in R&D. To date, this is the only known method that has been successfully deployed for in-situ materials characterization, as well as in the harsh environment of the metalworking industry. Combined with the enablers, introduced by the fourth industrial revolution, and the conjunction of a laser ultrasonic system with a Smart Production Lab, it has great potential to contribute to lower rejection rates, better recyclability, and consequently to a more sustainable production. In this review, the potential for systemic sustainability is explained throughout a part of the value chain, in the context of Industry 4.0. In addition, the integration of the methodology into a miniaturized Smart Production Lab is demonstrated, with the intention of incorporating it as a substantial part of the creation of a digital twin. Such a lab is designed to serve as an interface between laboratory and industry, in order to reveal the possibilities of digital transformation, Industry 4.0, and the application of highly flexible systems such as the laser-ultrasonic system for companies.

This study investigates the performance of a centrifugal radial turbine within an Organic Rankine Cycle (ORC) system, focusing on operation beyond the design point due to variable waste heat sources. With the goal of integrating the turbine into optimal ORC operating conditions, its performance was analyzed using R245fa as the working fluid over three stages with varying numbers of blades. A detailed computational analysis was performed using Ansys CFX software (Version 2020 R2) with the k-ω SST turbulence model using thermodynamic data from the NIST Refprop database. The results showed significant discrepancies when operating beyond the design point. At an inlet pressure of 780 kPa, the turbine internal power was calculated to be 120 kW—double the manufacturer’s maximum of 60 kW—and the mass flow rate exceeded 6 kg/s compared to the design value of 2.72 kg/s. These results highlight the challenges of adapting the turbine to fluctuating waste heat conditions, as factors such as tip clearance, blade geometry, and high outlet pressure have a significant impact on efficiency and system performance.

We demonstrate a thulium-doped, mode-locked, all-fiber laser capable of operating in two generation regimes: dispersion-managed soliton and noise-like pulse (NLP). Employing a nonlinear optical loop mirror as an artificial saturable absorber, the oscillator generated optical pulses with a fundamental pulse repetition frequency of ~15.795 MHz. The total net dispersion of the laser cavity had a slightly anomalous group delay dispersion value of −0.016 ps2. After appropriate adjustment of a polarization controller, bound states of a dispersion-managed soliton composed of three pulses with fixed soliton separations were also observed. NLP generation, tunable over 35 nm from 1943.5 to 1978 nm, was also presented in the same laser setup. To our knowledge, this is the first report of the generation of tunable NLPs in a mode-locked thulium-doped fiber laser based on a nonlinear loop mirror saturable absorber.

The work contains an original comparison of selected algorithms using artificial neural network models, such as RBF neural networks, and classic algorithms, approaches that are based on structured programming in the image identification task. The existing studies exploring methods for the problem of classifying musical notation used in this work are still scarce. The research of neural network based and the classical method of image recognition was carried out on the basis of the effectiveness of recognizing the notes presented on the treble staff. In order to carry out the research, the density of the data distribution was modeled by means of the probabilistic principal component analysis, and a simple regression was performed with the use of a radial neural network. The methods of image acquisition and analysis are presented. The obtained results were successively tested in terms of selected quality criteria. The development of this research may contribute to supporting the learning of musical notation by both beginners and blind people. The further development of the experiments can provide a convenient reading of the musical notation with the help of a classification system. The research is also an introduction of new algorithms to further tests and projects in the field of music notation classification.

This article presents the results of a study of the braking process in terms of assessing the longitudinal loading condition of transported cargo. The existing methods of securing cargo do not take into consideration the type of vehicle used to transport the cargo. This may result in cargo not being transported in compliance with the principles of proper cargo protection. This paper discusses the differences in maximum deceleration values achieved by different types of vehicles that are structurally suitable for freight transport. As a result of these differences in deceleration values, the values of forces acting on the transported cargo are also different. This paper presents and analyses the results of road tests that entailed the heavy braking of two vehicles structurally suitable for freight transport. One of them was a delivery vehicle, while the other was a semi-trailer truck. The experiment was carried out in six measurement series. Four of them were performed on an asphalt pavement, while the other two on a concrete pavement. One series included ten brake tests. Deceleration values registered during the tests were later used to determine the values of coefficient Cx, which were then compared with standardised values. It has been shown that failure to take into account in the selection process of cargo securing equipment, vehicle category, and type and condition of the pavement can result in cargo displacement and even traffic incidents.

Problems related to controlling the dynamics of machines and devices have been a major engineering challenge for many decades [...]