Search Results (572)

Achieving strong adhesion in underwater or humid environments remains challenging because the interfacial hydration layer prevents direct contact between the adhesive and the substrate. Conventional adhesives typically fail under these conditions, so new strategies are needed to actively displace the water layer and create stable interfacial interactions. In this study, we prepared a series of copolymers with different monomer ratios via photocuring, using methacrylic acid (MAA) and stearyl methacrylate (SMA) as monomers. We focused on their thermal transition behavior and adhesion performance under both dry and underwater conditions. The results show that at an SMA molar fraction of 85%, the copolymer exhibits crystalline melting between 30 and 40 °C, where the storage modulus drops from approximately 10⁷ Pa to 10⁴ Pa, indicating a stiff-to-soft transition. Under dry conditions, this composition shows an adhesion strength of 1.67 MPa to glass, which remains 1.2 MPa underwater, and it can support a hanging load of 5 kg. The copolymer adheres well to glass and aluminum but shows weak adhesion to PTFE. After surface abrasion, the adhesion strength to glass increases to 1.6–1.8 MPa. In summary, the copolymer achieves effective underwater adhesion through the synergy of hydrophobic water displacement, thermally induced stiff-to-soft switching, and hydrogen bonding. Full article

The increasing adoption of electric vehicles (EVs) demands highly efficient bidirectional DC–DC converters capable of seamless energy transfer between the grid and vehicle batteries. This paper introduces a Fixed-Frequency Dual-Active-Bridge (DAB) resonant converter featuring four degrees of freedom, achieved through a combination of triple phase-shift (TPS) modulation and a current-controlled variable inductor (VI). The proposed control strategy aims to minimize conduction and switching losses by simultaneously managing reactive power, RMS current, and soft-switching conditions across wide variations in voltage and power. Unlike conventional phase-shift or variable-frequency modulations, the fixed-frequency operation maintains full zero-voltage switching (ZVS) for the two bridges, and zero-current switching (ZCS) in the bridge that is receiving energy, enhancing overall system reliability and control simplicity. The proposed converter is validated through simulations and experimental results from a SiC MOSFET-based 14 kW prototype operating at 122 kHz, demonstrating peak efficiencies above 97% under both charging and discharging modes. The experimental results confirm that the proposed DAB topology and modulation scheme significantly improve efficiency and controllability, making it a promising solution for next-generation on-board chargers and vehicle-to-grid (V2G) applications. Full article

After a severe outage occurs, restoring a distribution network can take from several hours to days, making the secure and stable operation of restoration areas (RAs) critical. During a post-disaster partitioned operation, asymmetric controllable distributed generator (CDG) regulation capacity, non-controllable distributed generator (NDG) fluctuation risks, and concentrated high-value loads cause significant inter-area power imbalances. Soft open points bridge this resource gap by integrating electric vehicle charging directly into soft open points via vehicle-to-grid (V2G) technology; the resulting electric vehicle-embedded soft open points (EV-SOPs) acquire storage-like energy transfer capability. This paper proposes a boundary–node coordinated optimization strategy for post-disaster RA operation, which integrates CDGs, NDGs, smart switches, and EV-SOPs. Firstly, the boundary dynamic updating model with a multi-homogeneity indicator—load importance, NDG fluctuation risk, and CDG flexibility—enables adaptive resource allocation. Secondly, the optimal operational model of RA is formulated considering the various characteristics of facilities and topology constraints. Thirdly, EV-SOP uncertainties in response reliability, discharge power, and energy capacity are characterized by Bernoulli, log-normal, and truncated normal distributions, reformulated into a tractable mixed-integer quadratically constrained programming via chance-constraint interval linear transformation, and solved by a sequential weight-based priority search with hot-start strategy. Case studies on the IEEE 123-bus system verify the effectiveness of the proposed method. Specifically, the dynamic boundary strategy reduces the comprehensive weighted index by up to 29.10%; physical feasibility truncation reduces EV-driven load loss from 3.2073 MW to 3.1038 MW; and the sequential weight-based priority search with hot-start strategy achieves a cone constraint satisfaction measure of 9.3175 × 10⁻⁷, confirming robust convergence. Full article

Background/Objectives: This narrative review aimed to critically assess the role of multi-unit abutments in implant dentistry, focusing on mechanical reliability and biological stability at the implant–abutment interface. Methods: A literature search was performed in PubMed/MEDLINE, Scopus, Web of Science and Google Scholar to identify clinical studies and experimental research from the past 20 years addressing implant–abutment connections, mechanical complications and biological integration of multi-unit abutments. Results: Dental implants demonstrate survival rates above 95%, yet complications, up to 35%, are primarily linked to the implant–abutment interface. Mechanical issues, especially screw loosening, may be mitigated with conical connections and adherence to evidence-based protocols. Biologically, multi-unit abutments with sufficient transmucosal height contribute to stable supracrestal tissue and preservation of marginal bone. Advances such as nanostructured surfaces and the concept of mucointegration represent a shift toward biologically active interfaces, enhancing peri-implant soft tissue health. Conclusions: Multi-unit abutments have evolved from simple angulation-correction tools to essential components across a wide range of clinical applications. Their success relies on strategic, protocol-driven use that integrates mechanical strength with biological harmony, enabling potentially favorable outcomes in modern implant dentistry, particularly in well-selected clinical scenarios. Full article

Background/Objectives: Anterior cruciate ligament (ACL) injuries are common in sports; they can be seen with an arthroscope in more than half of instances of acute traumatic hemarthrosis and are frequently associated with meniscal tears. By reducing soft tissue injury and enabling faster recovery while attaining comparable long-term outcomes, the switch from open surgery to arthroscopic ACL repair (ACLR) has transformed treatment. However, maintaining efficient intra-articular visualization is essential for both patient safety and surgical precision. Methods: Using the PRISMA guidelines, a comprehensive systematic search was conducted across major medical databases, including PubMed, Web of Science, and ScienceDirect. The search strategy incorporated key terms such as epinephrine, irrigation fluid, and ACL reconstruction to identify relevant studies. The study focused on English-language clinical studies within the last 10 years that clearly assessed the safety and efficacy of epinephrine-added irrigation in ACL repair. The study design, patient demographics, specific outcomes (visualization, operation time, hemodynamics), and statistical findings were all carefully retrieved. The results were combined to determine the intervention’s safety profile and clinical value. Results: The pooled analysis demonstrated that the intervention group significantly decreased operating time (SMD = −0.51, 95% CI: −0.90 to −0.12, p = 0.01; I² = 24%). However, postoperative knee function showed no statistically significant difference between groups (OR = 1.80, 95% CI: 0.61 to 5.30, p = 0.29; I² = 0%). Postoperative pain levels also did not differ significantly between groups (SMD = −0.27, 95% CI: −0.63 to 0.09, p = 0.14; I² = 0%). Heterogeneity was low across all analyses (I² = 0–24%). Conclusions: Low-dose epinephrine in irrigation fluid significantly reduces operative time during arthroscopic ACL reconstruction, suggesting improved surgical efficiency. However, it does not significantly improve postoperative knee function or reduce pain compared to control irrigation. The intervention appears to be a reasonable alternative to tourniquets without major systemic cardiovascular effects. Nevertheless, preclinical data indicate potential chondrotoxicity. Therefore, while epinephrine can be considered to improve operating efficiency and reduce tourniquet-related problems, surgeons should weigh its use cautiously, especially in younger patients or those with susceptible cartilage. Full article

This paper presents a forecasting and optimization framework for the control of a hybrid renewable energy system (HRES) integrating solar, wind, and biomass generation with lithium-ion batteries, electrolyzers, and fuel cells. A bidirectional long short-term memory (bi-LSTM) neural network model was applied for renewable generation and load forecasting, while the deep Q-network (DQN) and soft actor–critic (SAC) algorithms were used for real-time supervisory control of energy storage and hydrogen-based components. The HRES was formulated as a Markov decision process (MDP), where the agents optimize battery charging/discharging, electrolyzer activation, and fuel cell operation under dynamically changing operating conditions. Experimental results demonstrated that the SAC agent achieved more stable learning dynamics and superior operational performance compared to the DQN agent, maintaining an HRES energy imbalance below 0.5 MWh while reducing unnecessary component switching and improving overall system stability. The obtained results confirm the potential of deep reinforcement learning for adaptive and low-emission supervisory control of complex hybrid renewable energy systems. Full article

To supply indispensable transient inertia and damping support for power systems, particularly weak grid scenarios, grid-forming (GFM) generation exhibits superior performance compared with traditional grid-following (GFL) interfaces. Nevertheless, conventional GFL/GFM mode transition schemes suffer from abrupt switching behaviors or slow dynamic responses, which easily induce relay maloperation and even large-scale system instability. To tackle these drawbacks, this paper presents a seamless operating mode switching strategy for inverter-based power generation units. By coordinately optimizing the output states of phase-locked loop (PLL) and multi-loop current controllers, severe transient voltage and current surges during mode transition are effectively suppressed. A 2 MW grid-connected energy storage system is developed to validate the proposed control algorithm. The results demonstrate the feasibility and effectiveness of the proposed seamless switching strategy under grid-connected energy storage system scenarios. Full article

Micro- and nanoscale mass sensing is crucial for applications such as molecular detection and wearable monitoring. However, the observation of mass perturbations in flexible composite structures requires systematic theoretical evaluation. This study develops a dual-mode vibration-based mass-sensing model based on a film–substrate composite strip. By releasing and re-stretching pre-strain in the soft substrate, the ribbon can reversibly switch between a two-dimensional flat configuration (Mode 1) and a three-dimensional buckled configuration (Mode 2), leading to distinct dynamic responses. Under a finite-deformation Euler–Bernoulli beam assumption, displacement fields and kinematic relations are formulated for both configurations. An energy-based approach is employed to decompose the total energy into stretching and bending contributions, while an added-mass block is incorporated into the kinetic energy as a lumped mass. The governing equations of motion are derived using the Lagrange equations and the Hamiltonian function. Based on these results, the influence of the added mass on displacement signatures is examined, and the mode-dependent observability in the flat versus buckled states is compared, providing an analytical basis for mass sensor evaluation. Full article

The gap dimension of a railway switch machine is a critical physical quantity for determining the locking status of railway turnouts. Under operating conditions characterized by heavy oil contamination, complex illumination, and equipment vibration, existing visual measurement methods often struggle to maintain stability and achieve sub-pixel precision. To address this issue, this paper proposes a gap measurement method based on the fusion of vision and geometric features (G-VFM). The method first utilizes a confidence-aware optimized YOLOv8 model to achieve robust localization of the gap region. Subsequently, an improved multi-channel U-Net is employed to extract soft-edge probability maps, based on which a 20-dimensional structured geometric descriptor is constructed. Finally, visual semantic features and geometric priors are fused for regression through an R34-Fusion two-stream residual network, and systematic errors are corrected using a weighted Huber loss combined with a piecewise linear calibration strategy. Test results on a constructed field dataset show that the proposed method achieves a Mean Absolute Error (MAE) of 0.0076 mm and a maximum error of 0.0193 mm. It achieves a 100% pass rate under an industrial tolerance of 0.02 mm, with an end-to-end inference time of 52.23 ms (~19.15 FPS), balancing both precision and efficiency. Further tests on illumination degradation, noise interference, and cross-batch evaluations indicate that the method maintains relatively stable performance across various complex scenarios. However, performance decreases significantly under extremely low-light conditions, suggesting that actual deployment may require integration with active lighting or multi-sensor fusion to ensure system reliability across all working conditions. Overall, this method achieves high-precision gap measurement under current experimental conditions and provides a feasible solution for vision-based switch machine status monitoring. Full article

Deploying unmanned aerial vehicles (UAVs) cooperatively with legged robots for disaster response and inspection requires autonomous docking on miniature walking platforms. This study addresses the problem of landing a foldable quadrotor onto the back of a trotting wheel-legged robot ($300\times 180$ mm) and subsequently taking off while carrying it as a payload. Four tightly coupled challenges distinguish this task from conventional mobile-platform landing: (i) an extremely small landing surface, (ii) gait-induced periodic vibrations at $2.5$ Hz, (iii) continuous platform translation at $0.3$–$0.8$ m/s, and (iv) surface docking that requires simultaneous position and attitude matching rather than mere point tracking. The proposed framework comprises four components: (1) a novel single-servo crank-rocker folding mechanism that reduces the folded body footprint by 48.5% and the maximum linear dimension from 590 mm to 309 mm (↓47.6%) compared with the prior dual-servo design; (2) a staged Continuous Fast Nonsingular Terminal Sliding Mode (CFNTSM) controller combined with a Gait-Frequency-Aware Finite-time Extended Observer (GFA-FEO); (3) a Feature-wise Linear Modulation Soft Actor-Critic (FiLM-SAC) residual reinforcement-learning policy conditioned on physical states and mission phase, with an adaptive trust weight $\lambda \left(t\right)$; and (4) a payload-adaptive takeoff strategy with parameter hot-switching to handle the twofold mass increase. Extensive Monte Carlo simulations and ablation studies across three experiment groups demonstrate that the proposed hierarchical framework achieves sub-centimetre (<10 mm) position accuracy and <3° attitude matching on a walking platform. Quantitatively, the full method reduces docking RMSE by 42% relative to the model-based CFNTSM + GFA-FEO controller without residual RL (4.2 vs. 7.2 mm) and reduces post-lock takeoff RMSE by 63% through FEO hot-switching (16.2 vs. 44.2 mm). Full article

Current-source DC links and their associated power converters require continuous conduction mode (CCM), necessitating specialized switching device configurations. These topologies have gained significant attention due to the increasing adoption of current-mode power distribution systems. The operation of a current-source DC-DC converter relies on temporary magnetic energy storage, typically regulated using established switch-mode power conversion techniques. For a stable current step up or step down the use of the tapped inductor concept can provide an ultimate stable solution for current adjustment and the proposed concept is now developed on a step-down current source DC-DC power converter for the first time to reveal in the power electronics field. The use of tapping concept is similar to a coupled inductor and this allows flexible current modification. In this article, this concept is extended to a family of Tapped inductor current-based DC-DC together with soft-switching to reduce the loss of the switching devices. The key advantage is that it can offer a wide range of current conversions with high efficiency. The theoretical and experimental analysis of the proposed converter family is presented. An experimental prototype of the converter was built and tested, operating with a switching frequency of 100 kHz and accommodating input currents ranging from 1 A to 10 A. The converter achieved current conversion ratios of 0.8, 0.67 and 0.57 times the input current, with an output power range of 1 W to 314 W. The maximum efficiency of 88% was achieved at an output power of 314 W. The high efficiency and wide current conversion range of this current-based converter make it suitable for a variety of applications such as current driving LED systems, photovoltaic (PV) system current source control, and constant current fast charging systems for electric vehicles (EVs). Full article

Power Line Communication (PLC) utilizes the existing power line infrastructure for data transmission and offers the advantage of low deployment costs. However, the PLC channel is subject to a highly complex network topology, frequent load variations, and noise as well as impulsive interference introduced by the switching operations of various electrical devices. As a result, it exhibits pronounced frequency-selective fading and time-varying characteristics. Under such challenging channel conditions, existing PLC transmission schemes are no longer sufficient to meet increasing performance requirements. This paper introduces the Chase combining mechanism of Hybrid Automatic Repeat Request (HARQ) into the PLC physical-layer link. At the receiver, soft information from multiple transmissions is accumulated, thereby improving the transmission stability and resource utilization efficiency of PLC under complex channel environments. Simulation results show that Chase combining can significantly reduce the bit error rate in the low signal-to-noise ratio region and enhance link reliability in complex PLC noise environments. Hardware implementation results indicate that the main overhead of this mechanism is concentrated in buffering and accumulation logic, demonstrating its feasibility for Field-Programmable Gate Array (FPGA) implementation. Full article

The growing use of electric vehicles (EVs) requires fast charging solutions capable of delivering high power levels with greater efficiency and less impact on the power grid. This article presents the design and simulation of a Level 3 fast direct current (DC) charger for electric vehicles based on an LLC resonant DC-DC converter. The proposed architecture incorporates an isolated LLC resonant converter, selected for its soft switching capability, low switching losses, and reduced electromagnetic interference (EMI). The main contribution of this work is the design and simulation of a 50 kW LLC resonant converter developed specifically for a Level 3 DC fast charger for electric vehicles, a power level that, to the authors’ knowledge, has not been previously described in the current scientific literature using this topology. For the proposed converter, it has been proposed to use commercially available wide bandgap (WBG) semiconductor devices specifically made of silicon carbide (SiC). This allows for high switching frequency operation, lower conduction and switching losses, and higher power density. The key design parameters, component selection, and operating principles are analyzed in detail. Simulation results demonstrate high conversion efficiency, reduced switching stress, and stable operation under fast charging conditions, validating the suitability of the LLC topology for high-power electric vehicle charging applications. The proposed system offers a scalable and efficient solution that can contribute to the development of compact, grid-compatible DC fast charging stations, supporting the growing demand for electromobility infrastructure. Full article

The central adjustment coil of a gasdynamic Electron Cyclotron Resonance (ECR) ion source requires wide-range bipolar current regulation over ±100 A with flat-top stability within 0.1% (1000 ppm) and a current rise time below 4 ms. Conventional fully controlled H-bridge converters operating under hard-switching conditions are unable to satisfy these requirements simultaneously, as the switching loss penalty restricts the control bandwidth and degrades flat-top stability. This paper presents an Asymmetrical Half-Bridge Flyback (AHB-Flyback) converter specifically designed for this application. By incorporating a dedicated resonant branch $L_r$–$C_r$ on the primary side, the converter achieves primary-side Zero-Voltage Switching (ZVS) and secondary-side Zero-Current Switching (ZCS) over the full operating range, enabling 100 kHz operation without incurring the switching losses that would otherwise limit control bandwidth. A decoupled energy management architecture is adopted in which the primary circuit pre-charges an energy storage capacitor during idle intervals, and the coil current is subsequently established through an autonomous capacitor-to-coil discharge, effectively decoupling the peak power demand from the upstream supply network. The operating modes of the flat-top maintenance stage are analyzed through time-domain state equations, yielding an explicit closed-form expression for the Mode 3 duty cycle $D_{T3}$. This expression demonstrates that $D_{T3}$ is determined solely by the switching frequency and circuit parameters, independent of the load current setpoint, which is the fundamental mechanism enabling stable wide-range current regulation without parameter re-tuning. Parameter selection guidelines are derived from this result. Simulation results across the 20–100 A operating range and experimental validation on a scaled prototype confirm flat-top current stability within 1000 ppm and a current rise time of 4 ms, demonstrating the suitability of the proposed converter for precision ECR ion source power supply applications. Full article

This paper presents a parallel genetic algorithm (GA) for the planning of power distribution networks considering harmonics. Power distribution systems are generally operated in a radial configuration, supplemented by tie switches that enable network reconfiguration during unexpected outages or planned maintenance. They can also include distributed generators (DGs), capacitor banks (CBs), and soft open points (SOPs) to lower distribution losses and improve the voltage profile. Some of the loads and DG units may be nonlinear, generating harmonic currents in the system, polluting the power, and increasing losses. This paper makes use of a parallel GA to find an optimized configuration, optimized location, and sizing of DGs, CBs, and SOPs to lower real power distribution losses while considering harmonics and the physical constraints of the network. The proposed algorithm uses a solution encoding based on the minimum spanning tree to guarantee the radial topology of candidate solutions. It uses the backward–forward power flow method to compute the fundamental voltages and a decoupled harmonic power flow for the harmonic components. The algorithm is parallelized on a small computer cluster using the Message Passing Interface (MPI) to reduce its execution time. The proposed solver is validated on distribution systems ranging from 16 to 880 buses. The results show that simultaneously optimizing the topology, the DGs, the CBs, and the SOPs results in reducing power losses by 37% to 93%, improving the overall efficiency of the distribution system. The parallelization using MPI allows for a 90.9× speedup on a 96-core cluster. Full article