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Snap loads generate sharp discontinuities in the axial tension distribution along the mooring line, thereby posing a numerical challenge for conventional methods. This study presents the comparison between an in-house high-order accurate nodal Discontinuous Galerkin (DG) method with the industry-standard OrcaFlex lumped-mass (LM) model. The DG method employs a conservative shock-capturing formulation to resolve tension discontinuities and wave propagation – an approach with limited application in literature. Two cases are examined: an experimental slack-taut catenary chain test and a numerical benchmark test using the OC4-DeepCWind platform. For mild environmental loading, both methods show excellent agreement in fairlead tension (RMSE within 0.4%). Under slack conditions prone to snap loads, however, the DG method accurately captures tension-shock propagation and reflection, while the LM model exhibits significant numerical smearing, mispredicting the tension peak location observed experimentally. These results motivate further investigation into the conditions under which lumped-mass models remain adequate, and where higher-fidelity approaches become necessary for reliable mooring design.

Irregular mounting surfaces in railway tunnels often cause low efficiency and repetitive adjustments during catenary hanger installation. To address this, this paper proposes an inclination measuring device and a shim thickness calculation algorithm. The system uses a dual-axis sensor and a geometric model to determine precise shim parameters for digital pre-assembly. Field tests show that the average installation time decreased from 42.5 to 16.8 min, and high-altitude readjustments were eliminated (dropping from 2.3 to 0). These results confirm that the device significantly improves installation efficiency and precision.

Increasing the speed of a pantograph deteriorates its aerodynamic performance and aggravates the problem of flow-induced vibration, which is not conducive to the stability of the pantograph - catenary system (PCS). Currently, commercial high-speed trains operate at speeds exceeding 350 km/h, with line test speeds exceeding 450 km/h, making the impact of airflow on pantograph dynamics increasingly significant. Therefore, a simulation study on the bidirectional coupling between pantograph aerodynamics and structural dynamics is urgently needed. This study proposes a bidirectional coupling method for the pantograph based on overset grids. The user-defined functions (UDF) in Fluent enable real-time data exchange between aerodynamic forces and structural displacements. The flow field was modelled using the Shear Stress Transport k-ω turbulence model and Reynolds-averaged Navier - Stokes equations, and the dynamics is computed by Newmark-Beta solving the differential equations. It was found that the calculation method in this study was reliable and efficient. The motion of the pantograph assembly in the flow field will change the airflow mode, thus affecting the aerodynamic characteristics of the assembly, and the high-frequency and stochastic aerodynamic excitation will lead to an increase in vibration of the pantograph assembly, especially at the contact strip. For example, when the pantograph operated in the knuckle-upstream direction at 450 km/h, it exhibited poor PCS interaction, with a mean contact force of 50 N, a standard deviation of 36 N, and an overall offline rate of 7%. This study introduced a novel approach to pantograph fluid - structure coupling, offering valuable insights for predicting high-speed pantograph performance and evaluating PCS interactions.

Catenary action plays crucial role in resisting the applied vertical load at large deformations stage in reinforced concrete (RC) structures. This paper aims to predict the catenary action capacity of RC beam-column substructures by utilizing the distinctive properties of gene expression programming (GEP). The input parameters selected for the modelling are: double-beam span-to-depth ratio, relative axial restraints stiffness, relative rotational restraints stiffness, bottom and top longitudinal reinforcement ratios, and yield strength of longitudinal rebars. A comprehensive and reliable database was collated from internationally published research articles to develop and verify the model. The GEP-based model was assessed by comparing its performance with regression based model. Various statistical indicators and external validation criteria suggested in literature proved that the model is accurate and possess high prediction and generalization capacity. Sensitivity analysis was carried out to show the contributions of the input parameters, while parametric analysis was performed to show that the proposed model is not merely a combination of the input parameters but can accurately represent the given physical system. The proposed formulation from GEP is found to be simple, robust, and easy to utilize for pre-design purposes.

In the pantograph-catenary sliding electrical contact of an electrified railway, friction and conduction are coplanar, which determines that pantograph-catenary friction and current collection are interactive. In order to study the coupling relationship between friction and wear and current receiving quality, based on experimental data, the evaluation index system of friction and wear and current receiving quality is established. The coupling coordination model of friction and wear and current receiving quality is constructed by the entropy method and coupling coordination degree, and its comprehensive level, coupling correlation degree, and coordination degree are studied. The results show that they are in a state of high coupling interval aggregation, and the coordination value first decreases and then increases with the increase in current. According to the coupling and coordination characteristics under different conditions, it provides a basis for the selection of pantograph-catenary system operating conditions and the formulation of optimization strategies.

As the unique power entrance, the pantograph–catenary electrical contact system maintains the efficiency and reliability of power transmission for the high-speed train. Along with the fast development of high-speed railways all over the world, some commercialized lines are built for covering the remote places under harsh environment, especially in China; these environmental elements including wind, sand, rain, thunder, ice and snow need to be considered during the design of the pantograph–catenary system. The pantograph–catenary system includes the pantograph, the contact wire and the interface—pantograph slide. As the key component, this pantograph slide plays a critical role in reliable power transmission under dynamic condition. The fundamental material characteristics of the pantograph slide and contact wire such as electrical conductivity, impact resistance, wear resistance, etc., directly determine the sliding electrical contact performance of the pantograph–catenary system; meanwhile, different detection methods of the pantograph–catenary system are crucial for the reliability of service and maintenance. In addition, the challenges brought from extreme operational conditions are discussed, taking the Sichuan–Tibet Railway currently under construction as a special example with the high-altitude climate. The outlook for developing the ultra-high-speed train equipped with the novel pantograph–catenary system which can address the harsher operational environment is also involved. This paper has provided a comprehensive review of the high-speed railway pantograph–catenary systems, including its progress, challenges, outlooks in the history and future.

In order to effectively solve the rust of rail catenary in underground coal mines, the advantages and disadvantages of physical rust removal, laser rust removal, and chemical rust removal are analyzed. The more suitable physical rust removal is selected. At the same time, the design requirements and functional requirements of the rust removal device are studied, and the rust removal device with automatic lifting, left and right offset compensation, and adjustable pressure is developed. The de-rusting work of the overhead contact line was successfully completed through the industrial test on-site, which verified the feasibility of the device, improved the efficiency of the dedusting of the overhead contact lines in the underground coal mines, and reduced labor intensity.

Accurate pantograph models are crucial to obtain reliable simulations of the pantograph-catenary dynamic interaction. Non-linearities can make it a challenge to find a model design that fits the dynamic behaviour of the real pantograph. In this work, we propose a novel pantograph model including a particular non-linear mechanism, whose dynamic behaviour significantly affects the pantograph response. This mechanism is composed of two rigid bars and an oblique pre-stressed spring with dry friction and exhibits a complex non-linear behaviour. The objective is to design a model capable of reproducing the behaviour of the real pantograph, which is represented by the dataset of dynamic measurements in the pantograph tests. From a proper parametric representation of the model, the optimisation of the parameters by a genetic algorithm has achieved a good agreement with the experimental data. The resulting optimised model behaves similarly to the real pantograph for a wide range of excitations that vary in type, amplitude and position. Since the higher number of simulations performed in the optimisation makes it necessary to use an efficient simulation tool, we propose an efficient strategy to integrate systems with Coulomb’s friction.

Rigorously designed sub-micrometer structure arrays are widely used in metasurfaces for light modulation. One of the glaring restrictions is the unavailability of easily accessible fabrication methods to efficiently produce large-area and freely designed structure arrays with nanoscale resolution. We develop a patterned pulse laser lithography (PPLL) approach to create structure arrays with sub-wavelength feature resolution and periods from less than 1 μm to over 15 μm on large-area thin films with substrates under ambient conditions. Separated ultrafast laser pulses with patterned wavefront by quasi-binary phase masks rapidly create periodic ablated/modified structures by high-speed scanning. The gradient intensity boundary and circular polarization of the wavefront weaken diffraction and polarization-dependent asymmetricity effects during light propagation for high uniformity. Structural units of metasurfaces are obtained on metal and inorganic photoresist films, such as antennas, catenaries, and nanogratings. We demonstrate a large-area metasurface (10 × 10 mm 2 ) revealing excellent infrared absorption (3–7 μm), which comprises 250,000 concentric rings and takes only 5 minutes to produce. Fabrication of metasurfaces with nanoscale structures is inefficient for large areas. Here, the authors introduce patterned pulse laser lithography for creating structured arrays with sub-wavelength feature on large-area thin films under ambient conditions.

The interaction between the catenary and pantograph is one of the most crucial factors that determine the train operation in high-speed railway. The bad state of catenary is able to directly influence the power supply safety of traction power system. In this paper, four aspects on the catenary research of high-speed railway are reviewed in detail, namely the solution methods for catenary equilibrium state, the dynamic modeling methods of catenary, non-contact detection methods of catenary, and the static and dynamic evaluation methods of catenary. In addition, their recent advances are described. For the low solution accuracy of the initial equilibrium state of catenary, the structure finding method with multi-objective constraint and nonlinear finite element procedure are introduced to solve the problem. For the catenary’s dynamic modeling, considering the influence of environmental wind on the catenary, environmental wind simulations and wind tunnel tests are used to obtain the aerodynamic coefficients and build the wind field along the catenary for analysis of its wind vibration characteristics. In order to improve the detection accuracy of non-contact detection for the catenary, the deep learning theory and real-time detection algorithms should be adopted in the future. In view of the lack of dynamic assessment method for the catenary, the modern spectrum evaluation, time–frequency analysis, big data technology and their combinations will be the important means for future catenary evaluation.