Oxide-dispersion- and hard-particle-strengthened (ODS) laser-cladded single-layer multi-tracks with a Ni-based alloy composition with 20 wt.% μm-WC particles and 1.2 wt.% nano-Y2O3 addition were produced on ultra-high-strength steel in this study. The investigation of the composite coating designed in this study focused on the reciprocating friction and wear workpiece surface under heavy load conditions. The coating specimens were divided into four groups: (i) Ni-based alloy, nano-Y2O3, and 2 μm-WC (2 μm WC-Y/Ni); (ii) Ni-based alloy with added 2 μm-WC (2 μmWC/Ni); (iii) Ni-based alloy with added 80 μm-WC (80 μmWC/Ni); and (iv) base metal ultra-high-strength alloy steel 30CrMnSiNi2A. Four conclusions were reached: (1) Nano-Y2O3 could effectively inhibit the dissolution of 2 μm-WC. (2) It can be seen from the semi-space dimensionless simulation results that the von Mises stress distribution of the metal laser composite coating prepared with a 2 μm-WC particle additive was very uniform and it had better resistance to normal impact and tangential loads than the laser coating prepared with the 80 μm-WC particle additive. (3) The inherent WC initial crack and dense stress concentration in the 80 μm-WC laser coating could easily cause dislocations to accumulate, as shown both quantitatively and qualitatively, resulting in the formation of micro-crack nucleation. After the end of the running-in phase, the COF of the 2 μm-WC-Y2O3/Ni component samples stabilized at the minimum of the COF of the four samples. The numerical order of the four COF curves was stable from small to large as follows: 2 μm-WC-Y2O3/Ni, 2 μm-WC/Ni, 80 μm-WC/Ni, and 30CrMnSiNi2A. (4) The frictional volume loss rate of 2 μm-WC-Y2O3/Ni was 1.3, which was significantly lower than the corresponding values of the other three components: 2.4, 3.5, and 13.
As research on triboelectric nanogenerators (TENGs) continues to advance, their applications are becoming increasingly diverse and sophisticated. This paper aims to provide future researchers with a concise yet comprehensive understanding of the four fundamental operational principles of TENGs, enabling them to fully appreciate the unique characteristics and application scenarios of each mode. In doing so, researchers can make informed and well-grounded choices in selecting the most suitable operational mode for exploration and innovation, tailored to their specific fields and requirements. Furthermore, this paper aligns closely with the current research frontiers and development trends of TENGs by systematically reviewing the literature and analyzing recent developments in the field from three key perspectives: the expansion of application domains, innovations in structural design, and optimizations in material properties. Through this multidimensional framework, it not only highlights the broad potential and practical prospects of TENGs but also uncovers the latest advancements and future directions in technological breakthroughs and performance enhancement.
28 May 2025 in Proceedings of the Bulgarian Academy of Sciences
Based on the analysis of vibration signals modelled on a complex rotor system's impeller, such as an aviation gas turbine engine operating under steady-state conditions, this study demonstrates the influence of methodological factors – such as discrepancies in the natural frequencies of blade models, the sample length of the time series for the vibration process, and the sampling frequency – on the Hurst exponent value. The R/S analysis, or rescaled range method, proposed by H. Hurst for studying random processes, has provided a new perspective on the theory of random processes. This method has also become a highly effective and widely applied technical approach for examining a wide range of processes, from telecommunications and bioelectric signal analysis to solving functional diagnostic tasks for complex spatial objects. The findings of this study may be implemented within functional diagnostic systems for complex rotor systems to detect and predict the behaviour of damage in their rotating components.
Precise drug delivery remains a critical challenge in nanomedicine, with conventional nanocarriers suffering from significant drug leakage during circulation, limited control over release kinetics, and a lack of temporal control. This study presents a computational design and multiphysics simulation of a Smart Biodegradable Nanosystem. Through COMSOL Multiphysics simulations encompassing heat transfer, mass diffusion, and fluid dynamics, we validated the theoretical feasibility of a seven-layer architecture. The computational model predicts that mapping a re-entrant auxetic metamaterial topology onto a spherical scaffold enables geometric locking under fluidic stress, theoretically minimizing drug leakage. Furthermore, modeled thermosensitive dynamic covalent bonds demonstrate highly controlled release kinetics. All performance metrics presented herein are derived from predictive mathematical modeling. Theoretical degradation profiles indicate complete breakdown within 90–180 days into endogenous substances. This simulation-based study establishes a rigorous theoretical blueprint to guide future empirical fabrication in precision nanomedicine.