Search Results (234)

The return of the wolf is causing controversy. Herders (hereafter referred to interchangeably as shepherds) are among the groups most strongly affected and yet scarcely investigated. Using a mixed-methods online questionnaire, 82 German-speaking herders provided information on their assessment of the wolf’s return, their perception of the risk to their livestock, and their evaluation of the socio-political debate. Overall, the shepherds view the wolf rather critically; at the same time, their opinions are nuanced: opposition is less pronounced than might be expected based on similar studies. Negative assessments are grounded in three ethical lines of reasoning: agent-centered, since the wolf increases the workload and mental strain for the shepherds; anthropocentric, as it threatens pastoral farming; and pathocentric, because the grazing animals suffer from its presence. Positive assessments reflect biocentric–holistic arguments, according to which the wolf has a right to exist and is welcomed as part of a diverse natural environment. In addition, supporters point out that the wolf’s return leads to greater appreciation of the shepherding profession. The effectiveness of herd protection measures is subject to widely differing assessments. Generally, the wolf is considered one of several risk factors; however, unlike force majeure events such as lightning strikes or falls, the wolf is perceived by critical voices as anthropogenic and therefore avoidable. The perception that the wolf’s return has been intentionally facilitated by humans appears to reinforce the rejection. Respondents criticize the socio-political debate on the wolf as detached from practical realities, dominated by actors who lack on-site experience and are not directly affected. Full article

Optical ground wire (OPGW) cables are subjected to extreme electromagnetic stresses from lightning and short circuits. Existing models have three main limitations: (i) they assume uniform current distribution, (ii) they use constant material properties, and (iii) they do not couple the electromagnetic, thermal, and mechanical domains. This paper proposes a coupled multiphysics model that incorporates non-uniform current distribution with ${\mu }_r$ dependent on the magnetic field, temperature-dependent properties, and differentiated failure criteria. The model was implemented in COMSOL Multiphysics and was validated against experimental short-circuit tests (15–30 kA) conducted at the HPT-Laboratory (FEC). For the lightning scenario (10/350 μs impulse), the model predictions were compared with experimental results reported in the literature, showing good agreement in temperature rise and damage patterns. Results show that including a non-uniform current distribution modifies the predicted maximum temperature by 15.8% and shifts its location from the center to the outer aluminum layers. The model reproduces the experimental temperature with an RMSE of <7 °C and a relative error of <8%. A combined failure criterion (thermal + mechanical) predicts strand breakage with 89.2% accuracy, outperforming the purely thermal (72.5%) and mechanical (78.3%) criteria. Specific $I-t$ and $I^{2}t$ curves were generated for two commercial OPGW cable configurations (Manufacturer A and Manufacturer B), with $I^{2}t$ capacities at 500 ms of 128 kA²s and 98 kA²s, respectively. The proposed model provides a useful tool for protection selection and coordination in transmission lines with OPGW cables. Full article

Facing the demand of long-distance, high-voltage and high-power transmission, the research on MMC-UHVDC (Modular Multilevel Converter based Ultra High Voltage Direct Current) has become a hot issue. This paper focuses on the ±800 kV/8 GW UHVDC transmission system to conduct simulation modelling and insulation coordination studies. First, broadband models of the main circuit and primary equipment are established to simulate and analyse the distribution characteristics of both switching and lightning transient overvoltages under typical faults. Second, based on the overvoltage severity at critical nodes, two surge arrester configuration schemes with distinct internal valve protection topologies are proposed. Finally, an Improved Fuzzy Analytic Hierarchy Process (FAHP) is introduced to perform a quantitative techno-economic evaluation of the comparative schemes. The results demonstrate that the optimised configuration successfully suppresses extreme overvoltages at vulnerable sub-module nodes, maintaining adequate insulation margins. These research findings provide a highly reliable mathematical framework and engineering reference for the safe design of UHVDC systems. Full article

Wind turbines are persistently threatened by both lightning overvoltage and switching overvoltage due to their ultra-high structure, dense power electronics, and harsh operational environments, which severely endanger the safe and stable operation of the units. This paper systematically reviews the generation mechanism, type characteristics, and hazards of overvoltages in wind turbines. An internal and collaborative overvoltage protection system based on lightning protection zones (LPZs) is described. Focusing on three core protective devices—metal oxide varistors (MOVs), gas discharge tubes (GDTs), and Transient Voltage Suppressors (TVSs)—the research progress in material modification, structural optimisation, and performance evolution laws is explored. Additionally, the development of series-parallel topological collaborative design for multiple devices and active-triggered intelligent protection technologies is analysed. It is highlighted that current wind turbine overvoltage protection still faces bottlenecks in standard applicability, device operating condition adaptability, and system-level collaborative design. Future research should focus on the application of a wide bandgap and nanomaterials, the improvement of test standards tailored for actual operating conditions, and the construction of multi-physics coupling simulation and active intelligent early warning protection systems, so as to provide theoretical and technical support for high-reliability overvoltage protection of large-capacity and offshore wind turbines. Full article

In protected carbon fibre-reinforced polymer laminates subjected to simulated lightning strike, while thermal effects mostly affect the topmost UD plies, damage in the bulk, where temperatures can be far from the ablation temperatures of the composite constituents, is mainly the result of the explosion of the lightning protection layer, the supersonic plasma expansion shock waves, and the magnetic forces. In this work, previously validated three-dimensional models are applied to the analysis of lay-up and stacking sequence effects on the mechanical damage induced by simulated lightning strike on carbon/epoxy multi-directional laminates and compared with experimental observations in the literature. This work demonstrates that those observations can be replicated by the proposed models, predicting the effect of lay-up and stacking sequence not only on the orientation of mechanical damage, but also on its size. In addition, no effect on damage depth is predicted, which is also in agreement with available experimental observations. Finally, the models predict that laminates with thicker ply blocks have larger mechanical damage projected areas, which is also in agreement with experimental observations in the literature. While the previous literature had focused on the effect of the lay-up and stacking sequence on thermally induced damage, this work is a first attempt to predict those effects on the mechanical resistance, which in the future will be key to assessing lightning damage tolerance in protected composite laminates. Full article

To address the issue of coordination failure in multi-stage surge protective devices (SPDs) under lightning surges in communication power systems, this study employs traveling wave propagation theory and electromagnetic transient simulations using the PSCAD/EMTDC platform. It systematically evaluates how lightning strike location, interstage cable length, and load type affect energy coordination and overvoltage response in a two-stage SPD configuration. By combining time-domain and frequency-domain analysis, the coupling mechanism of SPD conduction timing is revealed. There exists a critical length for the interstage cable to ensure coordinated operation of the SPDs. This critical length decreases with increasing surge intensity but increases significantly with greater lightning strike distance. Incorporating an appropriate series inductor can provide the necessary time delay, serving as an alternative to using a long cable. For capacitive loads, although an excessively short cable can reduce the amplitude of oscillatory voltage spikes, it aggravates the surge steepness, thereby stressing the SPD. These oscillations can be effectively suppressed by installing a damping resistor in front of the SPD2. Furthermore, the study reveals a strong coupling between energy coordination and overvoltage behavior under capacitive load conditions, indicating that the two must be jointly optimized. The parameter configurations and practical recommendations presented offer quantitative design guidance for SPD selection, cable layout, and resonance suppression in communication power systems. Full article

This study conducts a comparative legal analysis of South Korea’s Framework Act on Artificial Intelligence (enacted January 2025, effective January 2026) and the EU AI Act (effective August 2024), focusing on the structural implications of their divergent regulatory philosophies for sustainable digital governance. Employing legal interpretive analysis (textual, systematic, and teleological) and comparative legal methodology, supplemented by risk-based regulation theory and the theory of hardening of soft norms, this paper examines three interconnected dimensions: the conceptual distinction between “high-impact” and “high-risk” AI, the legal nature of self-regulatory structures, and the potential distortion of civil liability attribution. The analysis reveals that Korea’s adoption of the “high-impact” concept, while strategically reducing compliance costs and avoiding stigma effects, generates significant legal gaps, including potential violations of the constitutional principle of clarity, a “liability lightning rod” phenomenon transferring responsibility from AI operators to frontline practitioners, and insufficient institutional prerequisites for effective self-regulation. In contrast, the EU’s ex-ante preventive framework provides greater legal certainty through direct enumeration of high-risk sectors and mandatory conformity assessments. Drawing on the growing body of EU AI Act scholarship, this paper proposes a five-step legislative model for dynamic regulatory adjustment tailored to Korea’s constitutional structure, encompassing statutory core criteria, periodic re-evaluation with parliamentary oversight, phased mandatory enforcement, and a presumption of conformity system, thereby offering a co-regulatory framework that balances innovation promotion with fundamental rights protection. Full article

Fuel vapor can be ignited by lightning through various means, particularly through hot spot formation on fuel tank skins. The wing fuel tank cover and its surrounding outer plates together form part of the aerodynamic shape of an aircraft. The lightning protection design of the fuel system, including wing fuel tank, is of great significance for ensuring the aircraft safety. Based on the Joule heating and implosion effect, the damage response of a composite fuel tank cover subjected to lightning strikes is analyzed in this paper. The adopted method combines electrical–thermal coupling with explicit dynamics analysis. Firstly, a finite element model of the fuel tank cover is established using electrical–thermal coupling elements, and the lightning current impact simulation is carried out under given electrical boundary conditions and thermal boundary conditions. On one hand, the ablation criterion is determined by the Joule heating effect and the sublimation temperature of materials. The thermal damage of composite materials subjected to transient high currents is obtained through transient thermal analysis. On the other hand, special implosion elements are selected according to the temperature distribution obtained from the electrical–thermal coupling analysis. The original composite material model in the implosion region needs to be replaced with a new material model described by the high-explosive material model and the JWL equation of state. The von Mises stress distribution and pressure distribution on the structure after implosion are discussed in detail. The results show that concave pits are formed near the implosion zone. Unlike the thermal damage morphology defined by the ablation criterion, the implosion effect makes the damage distribution deviate from the initial fiber direction of each layer. The implosion dynamic method reveals the internal damage and pit and bulge phenomenon around the lightning attachment area to a certain extent. Full article

Rapid and accurate calculation of lightning-induced electric fields in complex terrain is essential for lightning protection and electromagnetic compatibility analysis. Although conventional full-wave numerical methods such as the finite element method can achieve high-fidelity results, they are computationally expensive and inefficient for large-scale or repetitive engineering analysis. To enable efficient and reliable computation of lightning-induced electrostatic fields over complex terrain, this paper proposes a fast computational framework that integrates multi-level conformal mapping with a multi-objective optimization strategy based on the Non-Dominated Sorting Genetic Algorithm II (NSGA-II). In the proposed method, irregular terrain boundaries are transformed into analytically tractable domains using multi-level conformal mapping, while the critical mapping parameter is reformulated as a dual-objective optimization problem that simultaneously minimizes the maximum local error and the mean global error. Unlike traditional approaches that rely on empirical tuning or exhaustive traversal of mapping parameters, the proposed framework establishes a closed-loop adaptive optimization process that generates a Pareto-optimal solution set, enabling flexible trade-off selection according to practical accuracy requirements. The method is validated against high-fidelity finite element simulations for representative terrain profiles. The results demonstrate that the proposed approach achieves comparable maximum-error performance while reducing mean error and significantly improving parameter-optimization efficiency relative to exhaustive search methods. The proposed framework provides an adaptive and efficient computational solution for preliminary assessment of lightning-induced electric fields in complex terrain environments, and lays a foundation for future extensions toward more realistic multi-dimensional and transient analyses. The improvements in computational accuracy and efficiency offer significant practical value for rapid lightning protection assessment in large-scale complex terrain engineering, enabling parametric analysis and scheme comparison during the preliminary engineering design stage with sufficient reliability. Full article

Many countries are actively promoting the large-scale deployment of wind power generation, both onshore and offshore. However, damage to wind turbines caused by winter lightning has become a growing concern in Japan. Japan has made efforts since an early stage to establish legal frameworks for reducing lightning damage; nevertheless, lightning damage to wind turbines remains a problem that has not been completely eradicated. After a wind turbine has been struck by lightning, it is restarted only after its structural integrity has been verified; however, the current method relies on visual inspection by workers, making accurate and rapid inspections difficult. One approach to solving this problem is to use anomaly detection techniques based on SCADA data. Research is currently underway to implement this approach. However, anomaly detection methods based on SCADA data have been criticized for their limited ability to accommodate multiple operating modes, including de-rated operation. In this study, we propose the “scaled power curve” as a robust feature that is less affected by operating modes, with its effectiveness verified through anomaly detection. This method showed improved anomaly detection accuracy compared to using the original power curve as a feature; moreover, in the present case, the method remained effective under de-rated operation. By using this feature, it is expected that a lightning damage detection model can be developed, contributing to improved availability of wind turbines. Full article

Payment channel networks enable scalable off-chain payments, but their practical deployment remains constrained by a persistent tension among routing efficiency, liquidity visibility, transaction privacy, and settlement security. Existing multipath routing mechanisms can improve payment success under fragmented liquidity, yet they often expose sensitive balance information, leak structural features of payment routes, and enlarge the attack surface for probing, channel exhaustion, and selective forwarding. This paper presents a novel framework, Adaptive Multipath Proofs (AMPs), for privacy protection and security in payment channel networks. The core idea is to bind multipath routing decisions with lightweight zero-knowledge verifiability, allowing intermediate nodes to validate path feasibility, fragment consistency, and settlement constraints without learning exact channel balances, the complete payment amount, or the global route structure. AMP integrates three mechanisms: a hidden-liquidity feasibility proof that supports privacy-preserving route selection, an adaptive payment-splitting strategy that dynamically determines fragment allocation according to network congestion and balance uncertainty, and a proof-coupled settlement guard that enforces atomicity and timeout consistency across all payment fragments. Together, these mechanisms reduce information leakage while preserving robust payment execution under dynamic network conditions. Experimental evaluation on real Lightning Network topologies and synthetic stress scenarios demonstrates that AMP significantly lowers balance disclosure and endpoint inference risk, improves payment completion under skewed liquidity distributions, and introduces only moderate computational and communication overhead. The results indicate that adaptive proof-carrying multipath routing offers a practical and effective direction for building secure, privacy-preserving, and high-success payment channel networks. Full article

Lightning-induced breaking accidents of medium-voltage insulated conductors pose a serious threat to the safety of distribution networks, and the key cause lies in the establishment and sustained combustion of the power-frequency follow-current arc after lightning overvoltage breakdown. This paper systematically investigates the formation mechanism and critical conditions of power-frequency follow-current arcs using combined simulation and experimental approaches. Based on the streamer discharge theory, a lightning breakdown model was established and combined with the arc energy balance equation, revealing that the establishment of power-frequency follow-current arcs is essentially determined by the post-breakdown energy competition process. The simulation results show that the required anode electric field strength for lightning breakdown is not less than 3 kV/mm. When the power-frequency voltage reaches 10 kV, Joule heating of the arc continuously exceeds heat dissipation loss, enabling restrike after zero-crossing and sustaining stable burning. Experiments verified this voltage threshold and further revealed that the arc establishment rate exhibits nonlinear growth with increasing power-frequency voltage, exceeding 90% at power-frequency voltages ≥ 10 kV. The study also reveals that increased gap distance reduces the arc establishment rate, while the introduction of insulators can enhance it by approximately 20%. This study clarifies the energy criterion for power-frequency follow-current arc establishment and the influence patterns of key parameters, providing theoretical basis and engineering reference for lightning protection design and arc suppression in medium-voltage insulated lines. Full article

The lightning strike protection (LSP) performance of nickel-coated carbon fiber nonwoven veils (NiCVs) with varying areal densities, integrated onto the surface of CFRP laminates, was evaluated through simulated lightning strike tests. Post-strike damage was evaluated through visual inspection, non-destructive ultrasonic testing, residual strength measurements, and microstructural examinations. Results indicated that the protection effectiveness improved with increasing NiCV areal density. The laminate with a 68 g/m² NiCV layer showed substantially reduced damage—its damage volume, damage area, and maximum damage depth decreased to 18%, 40%, and 51% of those of the control laminate—and it retained 95% of the reference compression strength, demonstrating the strong post-strike protection capability of this lightweight veil. A detailed analysis suggested that the NiCV LSP performance may arise from a mechanism involving high electrical conductivity, a thermally stable coated-fiber skeleton, as well as a distributed nonwoven network architecture. These results highlight NiCV as a promising functional approach for enhancing the lightning strike protection of CFRP aerostructures. Full article

As distribution networks become increasingly intelligent, primary–secondary integrated distribution switches are replacing the traditional electromagnetic type. However, the high degree of integration intensifies inherent electromagnetic compatibility (EMC) challenges. This paper presents a field-circuit hybrid full-wave model to investigate switch characteristics during lightning strikes. A 3D full-wave model of the switch and a distributed parameter circuit model of the connecting lines are coupled via a network parameter matrix. This approach comprehensively accounts for the impacts of transmission lines and structural components on electromagnetic disturbances. Simulation and experimental results reveal that lightning strikes induce high-frequency damped oscillatory waves, primarily caused by traveling wave reflections along overhead lines. The characteristic frequency of disturbance is inversely proportional to the transmission line length. Additionally, internal components significantly influence this frequency; specifically, a larger voltage dividing capacitance in the voltage transformer results in a lower frequency. Model validation was performed using a 20 m transmission line setup. A 75 kV standard lightning impulse was injected into Phase B. At a distance of 500 mm from the voltage transformer, the measured radiated electric field amplitude was 14.12 kV/m (deviation < 5%), and the characteristic frequency was 1.11 MHz (deviation < 20%). These findings offer vital guidance for the lightning protection and EMC design of primary–secondary integrated distribution switches. Full article

Lightning rods, while essential for protecting weather radars from direct lightning strikes, act as persistent non-meteorological scatterers that can interfere with signal transmission and reception and thereby degrade detection accuracy and product quality. Existing studies have mainly focused on X-band and C-band systems, and robust, measurement-based quantitative assessments for S-band dual-polarization radars remain scarce. In this study, a controllable tilting lightning rod, a high-precision Far-field Antenna Measurement System (FAMS), and an S-band dual-polarization weather radar (SAD radar) are jointly employed to systematically quantify lightning-rod impacts on antenna electromagnetic parameters under different rod elevation angles and azimuth configurations. Typical precipitation events were analyzed to evaluate the influence of the lightning rods on dual-polarization parameters. The results show that the lightning rod substantially elevates sidelobe levels, with a maximum enhancement of 4.55 dB, while producing only limited changes in the antenna main-beam azimuth and beamwidth. Differential reflectivity ($Z_{DR}$) is the most sensitive polarimetric parameter, exhibiting a persistent positive bias of about 0.24–0.25 dB in snowfall and mixed-phase precipitation, while no persistent azimuthal anomaly is evident during freezing rain; the co-polar correlation coefficient (${\rho }_{hv}$) is only marginally affected. Collectively, these results provide quantitative, far-field evidence of lightning-rod interference in S-band dual-polarization radars and provide practical guidance for more reasonable lightning-rod placement and configuration, as well as useful references for $Z_{DR}$-oriented polarimetric quality-control and correction strategies. Full article