Kielce University of Technology

A gap test an experimental and numerical test, which is designed to show that the effective mode I fracture energy depends strongly on the crack-parallel normal stress. Talking about the fracture energy one should distinguish between the initial and the total fracture energy. According to Nguyen et al., the initial fracture energy is the area under the initial tangent of the traction–separation curve while the total fracture energy represents the area under the traction–separation curve. Alternatively one can estimate the total fracture energy as the area between the up-and-down curve and the horizontal yield line in the load-displacement diagram. Authors of this paper tried to recreate numerically the gap test with a concrete specimen and to calculate the total fracture energy. They used the concrete damaged plasticity model in Abaqus software. Results presented in this paper are continuation of the authors’ work, presented previously at the FraMCoS 2025 conference.

Smart cities, first proposed in the early 1990s, continue to face new opportunities, such as the prevalence of UAVs, and new challenges, such as the need to provide hard real-time communications with UAVs with delays of sub-10-milliseconds and little jitter or even no jitter. Although existing highly reliable, low-latency wireless networks are capable of meeting these challenges, there is a general agreement that classical transport protocols cannot effectively meet such stringent requirements. This paper investigates UAV-borne WebRTC-based IoT for its ability to provide low jitter in an outdoor, highly reliable network environment. The results of field experiments conducted under various network conditions show that WebRTC was able to ensure little fluctuation of end-to-end delays. Moreover, in the case of error-free transmissions, fluctuations were so small that jitter, expressed in milliseconds, was close to zero. The significant advantage of the WebRTC Data Channel over the classic web logical channel, i.e. WebSocket, in terms of jitter was also demonstrated.

<b>Introduction:</b> Voice prostheses (VPs) are devices that are widely used in voice rehabilitation of patients after laryngectomy. The main cause of VPs failure is their destruction by the growth of biofilm, mainly fungal. <br><br><b>Aim:</b> The aim of this study was to design and build a tracheoesophageal fistula (TEF) simulator to observe and analyse the process of biofilm formation on voice prostheses and its effect on the structure of the material from which they are made, in conditions as close to real as possible. <br><br><b>Methods:</b> Biofilm cultures were performed on voice prostheses under controlled in vitro conditions using a TEF simulator. Then, the crystal violet staining and confocal microscopic examination were performed. <br><br><b>Results:</b> The analysis of voice prostheses cultured in the TEF simulator conditions confirmed the presence of biofilm on their surface. <br><br><b>Conclusions:</b> The TEF simulator can be a valuable tool for future studies of silicone modifications that can limit the growth of biofilm on the VPs.

This study investigates heat transfer coefficients during two-phase flow boiling of distilled water within a horizontal, rectangular mini-channel with asymmetric heating. The microchannel dimensions are 180 mm × 4 mm × 1.5 mm. Experimental observations of flow structures were made through a transparent channel wall. Experiments were conducted under low Reynolds number conditions (281 ≤ Re ≤ 499), with measurements of inlet pressure, pressure drop, volumetric flow rate, heater power supply parameters, and temperatures at various points. The employed model assumed negligible influence of material properties on temperature and time-independent heat transfer. The flow resistance based on the two-phase separated flow Lockhart–Martinelli model was used to determine the water velocity profile in the mini-channel. The velocity profile satisfied the Poisson equation. The copper block and working fluid temperature distributions were assumed to adhere to appropriate energy equations with suitable boundary conditions. The Trefftz method was applied to solve these equations, providing the water velocity profile and 2D temperature distributions. Based on the calculated temperature distributions, the Nusselt number at the heating surface-water interface was determined. The experimental results were subsequently compared with theoretical correlations.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-34627-7.

ABSTRACT M CrAl X coatings are widely used as bond coats in thermal barrier coating systems to protect turbine blades from high‐temperature oxidation. However, their oxidation resistance is often restricted by uncontrolled microstructures, surface roughness, and aggregation of reactive elements (REs). In this study, high‐repetition‐rate femtosecond laser remelting (HRR‐FLR) is introduced as an advanced surface modification technique to overcome these limitations. Owing to its ultrafast self‐quenching and polishing effects, HRR‐FLR enables precise control of surface morphology, microstructural reconstruction, and REs redistribution. As a result, a uniform and periodic distribution of REs is achieved, which promotes the rapid nucleation and compact growth of α‐Al 2 O 3 and helps maintain the stability of the oxide scale under long‐term exposure. The HRR‐FLR‐treated coatings show remarkable performance, with the TGO growth rate reduced by approximately 80% and the oxidation lifetime extended to about 300 h compared with the untreated ones. Moreover, REs exhibit a dual function during oxidation: They act as preferential nucleation sites for Al 2 O 3 in the initial stage and segregate at TGO grain boundaries during growth, thereby suppressing outward cation diffusion. Overall, HRR‐FLR provides a novel and effective femtosecond‐laser‐based approach to tailor REs’ behavior and enhance the long‐term oxidation resistance of M CrAl X coatings, offering practical insights for the design of high‐temperature protective systems.

Predictive Health Management (PHM) for wind turbines using SCADA data is significantly challenged by Concept Drift, a phenomenon where the statistical relationship between sensor readings and impending faults shifts due to environmental seasonality and component degradation. In this research, model stability is investigated by comparing standard random validation protocols with a rigorous chronological split, where models trained on historical data are evaluated against future events. Initial models built exclusively on static features achieved high theoretical discriminative ability during internal testing (AUC-ROC 0.9422–0.9855) but exhibited a catastrophic performance degradation in chronological scenarios, with Recall falling to near-zero levels (0.0082–0.0159) and AUC-ROC decreasing to 0.5624. These results highlight the severe operational risks associated with non-stationary data. To mitigate this instability, Advanced Dynamic Feature Engineering was introduced, focusing on isolating the process of change through Delta (Δ) and Slope coefficients of critical SCADA signals. The resulting Advanced Model demonstrated consistent performance across the chronological split, achieving a Recall of 0.8406, a Precision of 0.9900, and an AUC-ROC of 0.9979. The findings suggest that dynamic features effectively separate stable mechanical failure signatures from volatile, environmentally induced baseline shifts. This work provides empirical evidence that a rigorous chronological validation strategy paired with dynamic feature engineering is essential for developing stable and deployable prognostic systems. Future research will focus on domain-generalizable representations and adaptive mechanisms to further enhance precision across diverse geographic locations and turbine configurations.

Abstract. In recent years, the manufacturing industry has undertaken several initiatives to enhance the monitoring of product life cycles by incorporating special markings directly during production. This is particularly important in today’s global market, where unambiguous identification of genuine products is essential. Such monitoring is becoming increasingly relevant, particularly in ensuring the reliable traceability of products and related services that manufacturers, retailers, and end-users can access. As a result, databases maintained by component manufacturers, which enable the storage of information about an individual product throughout its entire life cycle, now play a crucial role. In this context, the growing popularity, advantages, and ease of use of permanent product marking encourage its application in manufacturing technologies, including foundry processes, as well as in other industrial areas. Introducing a permanent imprint into the casting, without the need for laser processing or the use of non-durable self-adhesive labels, enables the unambiguous identification of each manufactured part, as highlighted in this article. The paper analyses the types and methods of producing permanent impressions in the mold, resulting in a negative imprint on the casting, as well as the techniques for reading the markings obtained in this way.

Abstract. This article presents the role of laser technology in modern military defense systems, with particular emphasis on its applications as direct energy weapons. The current uses of lasers in targeting, rangefinding, and communication are discussed alongside the prospects for deploying laser systems capable of neutralizing targets such as drones and missiles. The paper analyzes key technological challenges, including power management, thermal regulation, and the impact of atmospheric conditions on laser effectiveness. It also outlines applications of lasers in LiDAR, target designation, dazzling systems, and auxiliary operations such as cutting, welding, and repairs. The further development of advanced materials and optical solutions will be crucial for the successful integration of laser weapons into dynamic combat scenarios of the 21st century.