The article discusses electrically conductive filaments for FDM printing and, more specifically, the influence of printing parameters on the resulting conductivity of the component. First, the methodology of sample measurements is described. Then, a comparison of samples with 9 different printing parameters is made. Finally, three samples are selected for a detailed investigation of the influence of the printing parameters on the resulting electrical resistivity.
This paper presents a methodology for detecting excitation capacitor faults in self-excited induction generators (SEIGs) used in wind energy systems operating in isolated or rural areas. The proposed approach combines frequency and phase tracking with zero-crossing time rate analysis for real-time anomaly detection. The SEIG is modelled using the finite element method (FEM) to simulate its electromechanical behaviour under various fault conditions. Fault scenarios are introduced by progressively disconnecting excitation capacitors connected in parallel and series, thus simulating failures ranging from one to five units. Monitoring zero-crossing intervals and phase variations enables accurate fault detection without relying on computationally intensive spectral techniques. The results confirm the effectiveness of the proposed methodology in identifying fault-induced distortions and improving the reliability of SEIG-based wind energy systems.
The wastewater generated during showering represents a potential source of low-grade thermal energy that can be utilised to reduce the energy required for domestic water heating. This paper presents an experimental investigation of a shower wastewater heat recovery system in laboratory conditions. Measurements were carried out during summer and autumn periods under operating modes with and without heat recovery for 6- and 10-minute showering cycles. Temperatures and flow rates of the hot water, cold water, preheated cold water, mixed water, and wastewater were monitored. The results showed that the temperature of the cold water flowing through the heat exchanger increased by approximately 6–6.5 K. The experimentally determined heat exchanger efficiency reached 38–39 %, while the relative heat savings were approximately 23 %. The measurements also confirmed the effect of real operating conditions, particularly ambient temperature and non-insulated pipelines, on the measured parameters.
This article extends established methods for determining dosimetric quantities characterising monitored photon fields and for estimating the superficial activity of 137Cs and the concentrations of K, U, and Th in the soil surface layer from spectra acquired during in-situ environmental monitoring on the ground or using unmanned aerial systems (UASs). These methods are based on the response matrices of scintillation detection systems simulated using the Monte Carlo method and on the unfolding technique. This work implements these methods in a unified Python-based workflow for ground-based and UAS-borne scintillation spectrometry, with device-specific response matrices and response functions that directly account for soil water content and height above the ground. The software is complemented by newly established reference sites for unmanned aerial radiometric surveys. Together, they provide the infrastructure for testing and further development of the full acquisition-to-evaluation chain.
A key part in optimising the performance of fibre-reinforced concrete (FRC) lies in ensuring the correct orientation of fibres, especially in structural components where directional stress resistance is critical, such as beams and slabs. However, assessing the orientation of fibres in hardened concrete poses a significant challenge. This study explores the use of the non-destructive evaluation of fibre orientation within FRC by measuring a quality factor (Q-factor) of an electrical coil with an inserted FRC specimen. Through numerical simulations, the effectiveness of the Q-factor measurements were evaluated using several scenarios of fibre positions, quantity, and orientations. It was discovered that the Q-factor is sensitive to these variables and, therefore, it is a suitable tool for material diagnostics.
Real-time identification of living objects is becoming an integral part of intelligent systems, particularly in the automotive sector, for security applications, and in rescue operations. This study presents an in-depth analysis of current research into the use of artificial intelligence (AI), specifically neural networks, for detecting living entities using thermal imaging cameras, with a particular emphasis on low-visibility night-time conditions. The research focuses on the design, training, and evaluation of a multilayer perceptron (MLP) neural network. The network processes inputs, such as thermal intensity, pixel brightness, and object size, from segmented thermographic images to classify animals into five size categories and estimate their distance from the camera. The dataset was divided into training and testing sets, and the model achieved an accuracy of up to 92.4% for a five-metre range. The article further details dataset preparation, technical parameters of thermal sensors, experimental results, and prospects for integrating AI into intelligent vehicle systems.
This article proposes an approach to analysing the causes of part failure, which is based on using mathematical modelling to calculate mechanical loads and strength parameters by finite-element analysis. It then assesses the durability of the structure using methods of mechanics of damaged media that take into account the accumulation of structural defects in the material. The developed approach was used to calculate the critical loads that led to the destruction of a passenger car engine crankshaft and to establish the reasons for their occurrence. This also enabled technical solutions to be proposed to eliminate such emergency situations.
Accidents at level crossings are among the most serious transport collisions, given the severe consequences of these incidents, both material and, sadly, often fatal. Unfortunately, statistics inexorably show that the situation in this area is not improving. And how do drivers behave before crossing? The experiment conducted by the Brno University of Technology analysed the reactions of drivers immediately before entering a level crossing. The data obtained indicate a certain trend related to the age of drivers. Younger drivers have a slightly different view of safety perception and do not pay as much attention to certain facts and objects as they deserve, unlike older and more experienced drivers. So, what are the most common causes of collisions involving motor vehicles and trains? It clearly comes down to inattention, unpredictability, and awareness that the crossing area is an extremely dangerous place. The current state of accidents at level crossings is not at all favourable. It is necessary to improve drivers’ awareness of the dangers at level crossings. Although considerable attention is being paid to this topic, drivers’ awareness has not yet changed radically.
This study assesses the suitability of 2024T3 aluminium and Ti-6Al-4V titanium alloys for supersonic wing structures using the ONERA M6 configuration. Aaerodynamic loads at Mach 1.4, generated using CFD simulations, were applied in a finite element analysis to evaluate the material response. Results showed that aluminium, despite its low density, exceeds its yield strength and undergoes plastic deformation at angles of attack above 8°, indicating an insufficient structural robustness in the supersonic regime. In contrast, titanium remains fully elastic across all tested conditions, withstanding shock-induced loads due to its superior strength and stiffness. These findings demonstrate that the material criteria effective in subsonic design do not directly transfer to supersonic applications, where titanium alloys, despite their higher weight, offer a more reliable structural solution.
The combined deformation technology used to enhance the properties of gradient metal materials with a nanostructured surface layer has attracted significant attention due to their exceptional properties, making them highly promising for industrial applications. These materials exhibit a unique combination of high strength, ductility, and wear resistance. However, achieving the desired properties and gradient microstructure in these materials requires precise control over the deformation process. The objective of this work was to investigate the effect of combined deformation processing, integrating drawing through stationary (freely rotating) RSR mill rolls followed by die drawing, on the evolution of microstructure and the mechanical properties of initially coarse-grained alpha-brass. The laboratory experiment was conducted at a room temperature using rods with a diameter of 30 mm. The results revealed that introducing radial-shear broaching had a significant effect on the properties and microstructure of the material. The combined technological process of integrating radial-shear broaching through stationary rolls followed by die drawing, successfully produced a pronounced gradient microstructure in CuZn36 brass rods, where the grain size was refined to 1 μm in the surface zone while remaining at 20 μm at the centre. This structural refinement resulted in a symmetrical, U-shaped microhardness distribution across the cross-section, with peak values reaching 170 ± 4 HV0.1 in the heavily deformed surface layer compared to 84 ± 3 HV0.1 in the initial annealed state.
This study investigates the influence of dynamic disturbances on the stability performance of a PID controller applied to a single-axis gimbal stabilisation system. The primary objective is to quantitatively evaluate how kinetic disturbances and variations in input angular velocity affect the closed-loop stability, transient response characteristics, and tracking accuracy of the control system. A comprehensive mathematical model of the single-axis gimbal is developed, incorporating the rotational dynamics of the mechanical structure, the electrical and mechanical characteristics of the actuating motor, and the feedback mechanism provided by the gyroscopic sensor. The complete nonlinear model is subsequently linearised for controller design and stability analysis. PID control strategies are implemented and analysed within the MATLAB Simulink simulation environment to assess system behaviour under varying disturbance magnitudes and angular velocity inputs. In order to validate the theoretical findings, experimental studies are conducted on a RoboMaster platform, enabling a comparison between the simulation and real-world performances. Both simulation and experimental results consistently demonstrate that increases in dynamic disturbance amplitudes and reference angular velocities lead to a degradation in stability margins, prolonged settling times, and increased steadystate errors. These effects collectively reduce the precision and robustness of conventional PID-based stabilisation. The results highlight the limitations of classical PID controllers under high-disturbance conditions and provide quantitative insights into disturbance sensitivity of single-axis gimbal systems. This work establishes a foundation for the development of more robust control strategies that aim to improve the stability and disturbance rejection in precision stabilisation applications.
This paper addresses the critical engineering challenge of optimising the hydraulic efficiency and energy consumption of wet gas cleaning systems in thermal power plants. While Venturi scrubbers and packed columns provide high removal efficiency, they often suffer from excessive hydraulic resistance or fouling issues. This study focuses on determining the optimal geometric parameters of a vertically oriented spiral scrubber to ensure an energy-efficient operating mode for a medium-capacity industrial flow of 25 000 m3 h−1. Using a theoretical calculation model integrated with 3D-modeling (SolidWorks) and engineering verification (AutoCAD), we analysed the influence of the spiral channel geometry (helix inclination angle α, number of turns, and radius of curvature) on the generation of secondary flows and pressure drop (ΔP).The results indicate that the optimal configuration is achieved at α = 7°, ensuring a stable film regime and an active contact path of 36 meters. We proposed an optimised irrigation system configuration utilising 24–28 hollow-cone nozzles arranged across three vertical manifolds, achieving an ultra-low liquid-to-gas ratio ( L/G) of 0.55–0.70 kgm−3 while maintaining a stable phase contact through a high-gravity centrifugal field (10–15 g). A comparative analysis showed that this configuration ensures a total pressure drop of 397.4Pa at an inlet gas velocity of 7.7 ms−1, which is significantly lower than that of traditional Venturi apparatuses. The obtained dependencies provide a basis for the rational design of large-scale gas-liquid contactors with a reduced carbon footprint and lower operational energy penalties.
This study compares the dynamic initiation fracture toughness of five fibre-reinforced concrete materials with different types of fibre reinforcement. The base material was steel fibre-reinforced ultra-high-performance concrete (S). Four additional materials were created by incorporating various secondary fibre reinforcements into the base mix: aramid (SA), polyvinyl alcohol (SPVA), carbon (SG), and polypropylene (SP). Dynamic fracture initiation toughness was determined by conducting mediumspeed tensile tests on double-edge notched specimens. These tests were performed with a modified Instron Ceast 50 J instrumented Charpy tester, using a striking velocity of 3.8 ms−1 and a total impac energy capacity of 7.5 J. The polypropylene fibre-reinforced concrete (SP) exhibited the highest average dynamic initiation fracture toughness (171.4 kPam0.5) and also demonstrated the greatest impact toughness.
The increasing need for security measures in urban environments has highlighted the importance of effective anti-vehicle barriers. This paper presents the design, numerical simulations, and testing of an anti-vehicle barrier tailored for rapid deployment in cities. The proposed design strikes a balance between the need for high security and transportation and urban space constraints, while minimizing visual impact, and allowing pedestrian access. The effectiveness of the barrier against vehicular threats is evaluated through numerical simulations and real crash tests. The results offer practical insights for designing such protective barriers.
This article provides an in-depth analysis of the use of non-traditional secondary raw materials as a partial replacement for silica sand in the autoclaved aerated concrete (AAC). Three types of foundry sand from different sources and three varieties of waste glass (WG) were selected and subjected to experimental evaluation at substitution levels of 5 %, 10 %, and 15 %. The experimental verification reveals that using foundry sand and WG results in physico-mechanical and mineralogical properties comparable to, and in certain cases superior to, conventional AAC formulations. Conversely, brown and mixed WG led to the formation of atypical mineral phases, which significantly influenced the characteristics of AAC. Of the evaluated materials, foundry sand sourced from non-ferrous casting operations emerged as the most promising alternative, particularly at a 10% substitution, where enhanced strength and an optimised microstructure were observed. The article presents a structured experimental methodology, segmented into three stages: the selection and preparation of secondary raw materials, a comprehensive assessment of their physico-mechanical properties, and an advanced microstructural characterisation. The findings underscore the feasibility of using these secondary raw materials in AAC manufacturing without compromising material performance.
Reducing energy consumption and CO2 emissions has recently become a priority for the cement industry. The most effective approach appears to be replacing Portland clinker with high levels of supplementary cementitious materials (SCMs). The general approach is to use clinker with a high alite content and high reactivity, especially during the initial hydration phase. TiO2 is one of the common minor oxides in industrial clinker, typically present at about 0.3 wt. %. Previous studies have shown that TiO2 concentrations around 1% improve strength. This study investigates the performance of a TiO2-doped clinker (1 wt. %) in binary and ternary blends with calcined clay and limestone, focusing on its effect on hydration, rheology, and microstructure. The reactivity of cement pastes over 72 hours was determined using isothermal calorimetry, while rheological parameters and the thixotropy index were assessed during the first 45 minutes of hydration. The phase composition development was monitored using QXRD after 2, 7 and 28 days, and microstructure was examined using SEM-EDS (SE) after 2 and 28 days of hydration. The use of TiO2-doped clinker in LC3 shows a promising potential for sustainable cement production, owing to the synergistic effect of minor elements introduced into clinker minerals during firing and the high reactivity of limestone combined with calcined clay.
Combined sewer overflows (CSOs) represent a significant challenge in urban drainage systems, particularly during heavy rainfall events when their hydraulic capacity is exceeded. Effective separation of suspended solids in CSO structures is essential to reduce the pollutant load discharged into receiving waters. This study investigates the sensitivity of separation efficiency to various design parameters of a tube CSO using computational fluid dynamics (CFD). The chamber, designed as a part of a multifunctional hydraulic object of a real-world sewer network project, was analysed using numerical modelling, employing the Volume of Fluid (VOF) model and Lagrangian particle approach. The influence of two key design aspects, the total chamber length and overflow slot geometry configurations, was examined under different flow rate conditions. The results show a strong and consistent correlation between increased chamber length and improved separation efficiency, confirming the importance of sufficient residence time for directing the solids to the pumps. In contrast, modifications to slot geometry resulted in only minor and inconsistent changes in performance, suggesting that its impact may be dependent on specific flow dynamics and chamber configuration.
This study focuses on the influence of raw limestone materials on the fresh-state properties and early hydration behaviour of alkali-activated systems composed of blast furnace slag and metakaolin. Three types of limestone powders were examined in relation to their rheological impact, structural rebuilding (via oscillatory strain-amplitude sweeps and 3iTT tests), calorimetric behaviour, and thermal stability (TG/DTG). The results show that, at early stages, limestone primarily acts as an inert filler, but its particle morphology and impurity content significantly affect the system’s rheology and reaction kinetics. Limestone powder with high calcite content slightly accelerates structural regeneration and improves dispersion, while limestone powders containing clay minerals increase plasticity and stiffness due to water retention and enhanced interparticle interactions. Such clay-bearing powders can, however, also slow structural rebuilding and reduce flowability under shear. Calorimetry and thermal analysis confirmed that limestone powder addition, especially in low-calcium systems, promoted the formation of hybrid gels (C-(A)-S-H and N-A-S-H). Clay-related alumina also significantly affected both the early-age rheology and the reaction kinetics.
Portland cement clinker contains C3A as one of its key phases. During firing, it forms a melt that is essential for the formation of C3S and C2S. Commonly, two polymorphs of C3A are present: cubic and orthorhombic, and their presence influences the kinetics of cement hydration. This study focused on the effects of Na2O and Rb2O dopants on the polymorphic modifications of C3A. It was found that Na2O in concentrations of 0–2.5 % promotes the formation of the cubic polymorph, while higher concentrations, above 2.5 %, lead to a transition to the orthorhombic polymorph. For Rb2O, incompatibility with calcium was observed, resulting in the formation of new phases and the leaching of rubidium oxide at high firing temperatures. In terms of hydration, samples containing Na2O exhibited higher reactivity due to the presence of orthorhombic C3A, whereas Rb2O slowed down hydration, which remains an issue for further research.
Polymeric materials are widely used in military and defence applications, including personal and vehicle ballistic protection, protective masks and suits, vehicle components, and ammunition transport and storage packaging. In these applications, polymers are exposed to harsh environmental conditions and extreme temperatures, which can significantly affect their long-term performance. In this study, commercially available polymeric materials based on polyethylene (PE), polypropylene (PP) modified with thermoplastic elastomer (TPE) at different PP/TPE compositions, polyetheretherketone (PEEK), and polyamide (PA) were studied. The materials were exposed to selected chemical agents, namely fuels (gasoline) and decontaminants (hypochlorite decontamination mixture), as well as to climatic conditions including high (+100 °C) and low (−40 °C) temperatures, high humidity and UV radiation. The aim of this study was to determine the durability physical and mechanical properties of the polymers in the selected environments with increasing exposure time (from one to six weeks). Hardness (Rockwell and Shore methods), tensile strength, elongation, and tensile modulus were observed. The results showed that exposure to gasoline and UV radiation caused the most pronounced changes. Among the tested materials, PE exhibited the highest overall resistance, showing only minor degradation even under the most aggressive conditions, such as gasoline exposure and UV radiation.
