Search Results (1,152)

This study establishes a direct and quantitative link between field-scale monopile behavior, three-dimensional finite element (FE) modeling, and practical p-y curve formulations for large-diameter offshore monopiles. A validated three-dimensional FE model, benchmarked against a full-scale monopile field test, was employed to derive depth-dependent p-y curves under monotonic lateral loading and to evaluate the applicability of classical formulations proposed by Matlock and Reese. A systematic parametric analysis was performed to investigate the influence of pile diameter, embedment depth, and undrained shear strength of the surrounding soil. The results demonstrate that pile diameter and soil shear strength exert a dominant control on lateral stiffness and ultimate soil reaction, whereas embedment depth has only a minor influence on near-surface p-y behavior within the deep embedment range considered. Increasing the pile diameter leads to a transition from bending-dominated response to rigid-body rotation accompanied by three-dimensional soil wedge formation. Quantitative comparisons show that, at depths of 1–4 m and for working displacement levels of approximately 5–10 mm, FE-derived soil reactions are typically 3.0–4.8 times higher than those predicted by the Matlock formulation, as well as Reese curves. These findings demonstrate that classical p-y methods can significantly underestimate lateral soil resistance for modern large-diameter monopiles and highlight the necessity of calibrated three-dimensional FE analyses or FE-informed p-y modifications for reliable offshore wind turbine foundation design. Full article

Due to the negative resistance effect of power electronic devices, power systems with a high proportion of renewable energy face a significant resonance risk. To address this, this paper proposes a resonance-suppression strategy for high-penetration renewable energy systems based on an active amplitude and phase corrector (APC). Firstly, by considering its internal dynamics and complete control loops, the impedance model of the APC is derived. Next, the similarities and differences between resonance stability and harmonic resonance are analyzed using the s-domain and frequency-domain admittance matrices, concluding that resonance suppression for low-damping s-domain modes can be handled in the frequency domain. Then, a supplementary APC control strategy in the abc-frame is proposed, which improves impedance magnitude at specific frequencies while keeping the phase almost unchanged. Finally, the proposed strategy is validated through case studies on an offshore wind power system in Zhejiang Province. Full article

In response to the International Maritime Organization’s strengthened regulations on carbon emissions, the introduction of novel eco-friendly technologies for ship operators has become necessary. In this context, various energy saving devices such as wind-assisted propulsion systems (e.g., wing/rotor sails), propeller-rudder efficiency enhancers (e.g., pre-swirl stators or ducted propellers), and the gate rudder system have been proposed. Among various energy-saving technologies, the air lubrication system has been widely investigated as an effective means of reducing hull frictional resistance through air injection beneath the hull. The performance of air lubrication systems can be evaluated through experimental testing or computational fluid dynamics (CFD) simulations. However, accurately simulating air lubrication systems in CFD remains challenging. Therefore, this study aims to quantitatively evaluate the influence of numerical parameters on the CFD implementation of air lubrication systems. To evaluate these influences, CFD simulations employing the unsteady Reynolds-averaged Navier–Stokes (URANS) method were conducted to investigate air layer formation and sweep angle on a flat plate. The numerical predictions were systematically compared with experimental results by varying key numerical parameters. These quantitative estimations of the effects of numerical variables are expected to serve as a useful benchmark for CFD simulations of air lubrication systems. Full article

With the increasing penetration of wind power, the transient synchronization stability of doubly fed induction generator (DFIG)-based wind turbines during grid faults has become a critical issue. While conventional fault ride-through methods like Crowbar protection can ensure safety, they compromise system controllability and worsen grid voltage conditions. Virtual resistance demagnetization control has emerged as a promising alternative due to its simple structure and effective flux damping. However, its impact on transient synchronization stability has not been revealed in existing studies. To fill this gap, this paper presents a comprehensive analysis of the transient synchronization stability of DFIG systems under virtual resistance control, introducing a novel fourth-order transient synchronization model that explicitly captures the coupling between the virtual resistance demagnetization control and phase-locked loop (PLL) dynamics. The model reveals the emergence of transient power and positive damping terms induced by the virtual resistance, which play a pivotal role in stabilizing the system. Furthermore, this work theoretically investigates how the virtual resistance and current loop’s proportional-integral (PI) parameters jointly influence transient stability, demonstrating that increasing the virtual resistance while reducing the integral gain of the current loop significantly enhances synchronization stability. Simulation results validate the accuracy of the model and the effectiveness of the proposed analysis. The findings provide a theoretical foundation for optimizing control parameters and improving the stability of DFIG-based wind turbines during grid faults. Full article

Ventilated façade systems are being increasingly used in energy-efficient building envelopes due to their configurational flexibility and potential to reduce thermal bridging. This study focuses on the experimental evaluation of anchoring components used in such systems, specifically examining the effect of various thermal insulation pads and internal inserts on the system’s mechanical, thermal, and fire performance. A series of laboratory tests was carried out to assess the static behavior of aluminum brackets under both tensile (suction wind load) and compressive (pressure wind load) forces. The results demonstrate that the use of thermal pads and inserts does not lead to any significant degradation of the mechanical capacity of the anchoring brackets, confirming their structural reliability. Additional thermal testing revealed that the use of insulating materials significantly reduces heat transfer through the brackets. Fire resistance tests were conducted to compare the performance of different types of insulation pads under elevated temperatures. The findings indicate that the choice of pad material substantially influences both fire integrity and thermal performance. This study confirms the potential of incorporating optimized insulating pads and inserts into façade brackets to enhance the thermal and fire performance of ventilated façades without compromising their structural behavior. Full article

This study focuses on the design, material selection, and wind-induced fatigue analysis of a dynamic movable sculpture atop the Welcome Tower at Yazhou Bay Bougainvillea Park in Sanya. The sculpture, consisting of eight movable leaves, is driven by a hydraulic system enabling it to assume five distinct shapes. Nickel-saving stainless steel (S22152/S32001) was chosen as the primary material due to its excellent corrosion resistance and strength, ensuring durability in the harsh coastal environment. The mechanical system is designed with a two-level lifting device, rotation system, and push-rod mechanism, allowing the leaves to perform functions such as rising, opening, closing, and rotating while minimizing mechanical load. Wind tunnel tests and numerical simulations were conducted to analyze the sculpture’s performance under wind loads. Using the rain-flow counting method and Miner’s linear fatigue accumulation theory, the study calculated stress amplitude and fatigue damage, finding that the most unfavorable fatigue life of the sculpture’s components is 380 years. This analysis demonstrates that the sculpture will not experience fatigue damage over its expected lifespan, providing valuable insights for the design of dynamic sculptures in coastal environments. The research integrates mechanical design, material selection, and fatigue analysis, ensuring the sculpture’s long-term stability and resistance to wind-induced fatigue. Full article

This study focuses on the scale of wind and rainfall-induced soil erosion that is relevant to transportation infrastructure. To this end, an experimental approach was devised and carried out to assess the effectiveness of lignin, a biodegradable and non-toxic plant-derived biopolymer, in enhancing soil resistance to wind and rainfall-induced erosion. The experimental program included basic soil tests required for soil classification, wind and rainfall-induced erosion tests, pocket penetrometer tests to assess the near-surface soil strength, SEM, EDS scans, and FTIR spectroscopy to evaluate changes in the fabric and chemical composition of the soil treated with lignin. Additionally, the effect of lignin on the re-establishment of the vegetative cover after the construction completion was also investigated. It was found that an increased spraying rate of lignin solution increased both the near-surface strength and wind erosion resistance. Moreover, SEM scans showed that the presence of lignin provided abundant particle coating, which is a source of additional cohesive strength. However, the spraying rate had a minor effect on rainfall erosion resistance, which increased with an increase in lignin solution concentration. Finally, lignin treatment did not significantly affect the size of the vegetative cover and had a minor effect on soil nutrients. Full article

This paper presents research on an online preload detecting method for power transformer windings that is highly sensitive, survivable and repeatable. Traditional frequency response analysis methods exhibit limitations in sensitivity, accuracy, and interference resistance, making it difficult to detect small loosening. Although the FBG offer superior performance, quartz optical fibers exhibit limited deformation capacity and are susceptible to damage from short circuit impacts. To identify FBG placement locations with minimal impact exposure, this study compared FBG sensors at different installation positions through 42 short circuit impacts. Results confirmed that the FBG positioned at the top of pressure board experienced the least impact damage. Subsequently, a transformer equipped with this online preload detecting system underwent 12 short circuit impact tests. Simulation results and hoisting cover findings aligned with the FBG online detecting data. This study proposes an experimentally validated online preload detecting method, providing a reliable and reproducible technical pathway for transformer condition assessment. Full article

Reliable data availability and transparent governance are fundamental requirements for distributed edge-to-cloud systems that must operate across multiple administrative domains. Conventional cloud-centric architectures centralize control and storage, creating bottlenecks and limiting autonomous collaboration at the network edge. This paper introduces a decentralized governance and service-management framework that leverages Decentralized Autonomous Organizations (DAOs) and Decentralized Applications (DApps) to to govern and orchestrate verifiable, tamper-resistant, and continuously accessible data exchange between heterogeneous edge and cloud components. By embedding blockchain-based smart contracts within swarm-enabled edge infrastructures, the approach enables automated decision-making, auditable coordination, and fault-tolerant data sharing without relying on trusted intermediaries. The proposed OASEES framework demonstrates how DAO-driven orchestration can enhance data availability and accountability in real-world scenarios, including energy grid balancing, structural safety monitoring, and predictive maintenance of wind turbines. Results highlight that decentralized governance mechanisms enhance transparency, resilience, and trust, offering a scalable foundation for next-generation edge-to-cloud data ecosystems. Full article

This study investigates the sailing performance and maneuverability of a fully wind-powered ship equipped with two rigid wing sails and a rudder, using Computational Fluid Dynamics (CFD). Unlike some conventional approaches that separately analyze above-water and underwater forces, this research employs a comprehensive CFD model to predict ship motion and performance under various wind directions and sail angles, from a stationary state to steady sailing. The accuracy of the CFD method is confirmed through comparison with experimental drift test data. Although the simulated drift data showed some discrepancies from the observed data due to the difficulty of accurately modeling the wind field in the simulation, the results indicate that the CFD method can effectively reproduce the ship motions observed in the experiments. Simulations reveal that the previously proposed L-shaped and T-shaped sail arrangements, which were designed to maximize thrust without considering maneuvering effects, remain effective even when ship motion is included. However, the results also show that conventional sail arrangements can achieve higher steady-state speeds due to reduced leeway-related resistance, while the L-shaped and T-shaped arrangements yield distinct steady-state leeway (drift) characteristics under heading control. These findings suggest that dynamically adjusting sail arrangements according to operational requirements may help manage the ship’s trajectory (lateral offset) and mitigate maneuvering difficulties, contributing to the practical application of fully wind-powered ships. The study provides quantitative insights into the relationship between sail arrangement, acceleration, and leeway/drift behavior, supporting the design of next-generation wind-powered ships. Full article

Aeolian sand in arid mining regions is highly susceptible to wind erosion, posing serious threats to ecological stability and surface engineering safety. To enhance its resistance, this study applied the microbially induced carbonate precipitation (MICP) technique and conducted wind tunnel experiments combined with SEM and XRD analyses to examine the effects of cementing solution type and concentration, bacteria-to-cementation-solution ratio (B/C ratio), and spraying volume on the wind erosion behavior of MICP-treated aeolian sand. Results show that the cementing solution type and concentration jointly control erosion resistance. The MgO-based system exhibited the best performance at a B/C ratio of 1:2, reducing erosion loss by 47.2% compared with the CaCl₂ system, while a 1.0 mol/L concentration further decreased loss by 97.4% relative to 0.5 mol/L. Increasing the spraying volume from 0.6 to 1.2 L/m² reduced erosion loss by 70–99%, and a moderate B/C ratio (1:2) ensured balanced microbial activity and uniform CaCO₃ deposition. Microstructural observations confirmed that MICP strengthened the sand through CaCO₃ crystal attachment, pore filling, and interparticle bridging, forming a dense surface crust with enhanced integrity. From a symmetry perspective, the microbially induced mineralization process promotes a more symmetric and spatially uniform distribution of carbonate precipitates at particle contacts and within pore networks. This symmetry-enhanced microstructural organization plays a key role in improving the macroscopic stability and wind erosion resistance of aeolian sand. Overall, MICP improved wind erosion resistance through a coupled biological induction–chemical precipitation–structural reconstruction mechanism, providing a sustainable approach for eco-friendly sand stabilization and wind erosion control in arid mining regions. Full article

Wind power generation ships (WPG ships), which combine rigid sails for propulsion and underwater turbines for onboard power generation, have attracted increasing attention as a promising concept for utilizing renewable energy at sea. This study presents an integrated assessment of a WPG ship by combining towing-tank experiments, CFD simulations using ANSYS Fluent, and theoretical analysis to evaluate the coupled performance of sails, hull, and underwater turbines. First, sail thrust and bare-hull resistance were quantified to identify the effective operating-speed range under Beaufort 6–8 wind conditions, and the optimal number of rigid sails was determined. Based on a thrust–resistance balance at a representative rated operating point, two turbine configurations (two and four turbines) were preliminarily sized. The results show that ten rigid sails can provide near-maximum thrust without excessive aerodynamic interference, and the installation of turbines significantly reduces the feasible operating range compared to the bare-hull case. For the two-turbine configuration, a common effective ship-speed range of 6.58–8.0 m/s is obtained, whereas the four-turbine configuration is restricted to 6.58–7.44 m/s due to wake losses, additional appendage drag, and near-free-surface effects. The four-turbine configuration exhibits approximately 30% lower total power output than the two-turbine configuration. These findings demonstrate that an integrated, system-level evaluation is essential for WPG ship design and indicate that the two-turbine configuration offers a more favorable balance between power generation capability and operational flexibility. Full article

Wounded with second-generation (2G) high temperature superconductors (HTS) tapes, the conductor on round core (CORC) coil exhibits notable benefits such as low AC loss, powerful current-carrying capability, and great mechanical properties, which makes it one of the optimal materials for high magnetic field generation in the engineering applications for fusion magnets. However, it is challenging for current manufacturing techniques to ensure the uniformity among the joint resistances of HTS tapes in CORC coils. And it will have a crucial impact on the electro-magnetic properties of CORC coils. Therefore, a three-dimension (3D) finite element model of CORC coils considering joint resistance is established, and the effects of joint resistance on the coils’ current distribution and AC losses are analyzed. Results show that during AC operation, uneven joint resistances and reactance arising from the coils’ helical winding structure will act together on the current among HTS tapes, causing non-uniform current distribution and increasing the total AC losses of CORC coils. Additionally, the uneven degree of the joint resistance raises the CORC coil’s overall AC loss. Full article

Epoxy-based composites are crucial insulating and structural materials for superconducting magnets, providing mechanical strength, winding fixation, and heat transfer. However, future superconducting devices with higher integration and power will place even higher demands on their toughness, thermal conductivity, electrical insulation, and radiation resistance at low temperatures. Otherwise, problems such as cracking, detachment, and low heat dissipation efficiency will arise, which may lead to quenching of low-temperature superconductors (Nb₃Sn, NbTi) and a decline in the performance of high-temperature superconductors (YBCO). Research focuses on summarizing the recent progress in modifying epoxy resin to address these issues. The current strategies include formula optimization using mixed curing and toughening agents to enhance mechanical properties, incorporating functional fillers to improve cryogenic thermal conductivity and reduce the coefficient of thermal expansion. Studies also evaluate cryogenic electrical insulation performance (DC breakdown strength, flashover voltage) and radiation resistance under cryogenic conditions. These advancements aim to develop reliable epoxy composites, ensuring the stability and safety of superconducting magnets in applications such as particle accelerators and fusion reactors. Full article

Reliable detection of the rotor winding faults in the doubly fed induction generator (DFIG) is crucial for the resilience of the variable speed energy systems. High-resistance connection (HRC) and inter-turn short circuit (ITSC) faults cause current distortions that are remarkably similar, and the rapid rotor side dynamics and the DFIG multimode operation ability also make fault diagnosis more difficult. This paper proposes a three-layer diagnostic framework named ZSC-CASI-CADI which leverages three-phase rotor currents in conjunction with rotor zero-sequence current (ZSC) for comprehensive rotor winding fault diagnosis. Fault detection is realized through ZSC magnitude and the Cosine Angle Spread Indicator (CASI) enables the strong discrimination between HRC and ITSC faults using the dispersion of rotor current phasors from the ZSC reference. Fault localization is achieved using the Current Angle Difference Indicator (CADI), which determines the faulty rotor phase through the angular deviations in rotor currents from the ZSC. The methodology is verified with extensive simulation results to demonstrate the accurate, real-time fault detection, discrimination, and localization of DFIG rotor winding faults under different load and rotor speed conditions including sub-synchronous and super-synchronous modes. The results show that the proposed framework provides a light and effective solution for rotor winding fault monitoring of the DFIG systems. Full article