Electric pylons are crucial components of power infrastructure, requiring accurate detection and identification for effective monitoring of transmission lines. This paper proposes an innovative ...model, the EP-YOLOv8 network, which incorporates new modules: the DSLSK-SPPF and EMS-Head. The DSLSK-SPPF module is designed to capture the surrounding features of electric pylons more effectively, enhancing the model’s adaptability to the complex shapes of these structures. The EMS-Head module enhances the model’s ability to capture fine details of electric pylons while maintaining a lightweight design. The EP-YOLOv8 network optimizes traditional YOLOv8n parameters, demonstrating a significant improvement in electric pylon detection accuracy with an average mAP@0.5 value of 95.5%. The effective detection of electric pylons by the EP-YOLOv8 demonstrates its ability to overcome the inefficiencies inherent in existing optical satellite image-based models, particularly those related to the unique characteristics of electric pylons. This improvement will significantly aid in monitoring the operational status and layout of power infrastructure, providing crucial insights for infrastructure management and maintenance.
The leading-edge slat is an important contributor to airframe noise. Recent studies revealed that the leading-edge slat in realistic high-lift aircraft configurations forms a more complex ...nacelle/pylon vortex system, resulting in an intense noise source. Thus, this study investigated the noise characteristics of leading-edge slats in realistic aircraft configurations based on phased microphone arrays. The non-negative L1/2 regularization method for the deconvolution approach for the mapping of acoustic sources (DAMAS) was applied to the airframe noise benchmark test DLR1. An uneven and concentrated source strength distribution around the nacelle/pylon/slat juncture region was obtained owing to the three-dimensional flow pattern. Thus, the leading-edge region was partitioned into small sub-regions to extract the nacelle/pylon/slat juncture noise source. The angle of attack (AoA) has different effects on the slat and nacelle/pylon/slat juncture noises. In detail, the minimum amplitude of the slat noise was obtained at AoA = 5°. In contrast, the amplitude of the nacelle/pylon/slat juncture noise increased as the AoA increased, especially at a high AoAs. The significant increase in the amplitude of the nacelle/pylon/slat juncture noise was mainly attributed to the large increase in the spectrum at the low-frequency range with the increase in the AoA. In addition, the amplitude levels of the slat and nacelle/pylon/slat juncture noises approximately follow the fifth power law of the Mach number with their spectra following a similar scaling law. Both noise spectra followed the Strouhal number scaling laws in the low-frequency range and Helmholtz number scaling law in the high-frequency range. However, both noise sources have different noise generation mechanisms. The revealed noise characteristics are helpful for establishing a physics-based nacelle/pylon/slat juncture noise prediction model and subsequently, the development of noise reduction technologies.
This study, centered around the engineering context of the Wuxue Yangtze River Bridge, addresses the challenge of significant temperature-induced secondary internal forces in the short lower tower ...column. A novel open lower corbel tower scheme is proposed as a solution. Firstly, comprehensive finite element models are established for both the open lower corbel pylon scheme and the traditional lower continuous beam pylon scheme. These models are employed for finite element analysis to derive bending moments and displacements of the bridge pylon under various loads, including permanent, vehicle, temperature, and wind loads. Subsequently, considering internal force distribution and stiffness, a comparative assessment is made between the open lower corbel cable pylon scheme and the traditional lower continuous beam cable pylon scheme. The findings reveal that the open corbel structure bridge pylon exhibits lower transverse bending moment values under the influence of permanent load, vehicle load, temperature load, and wind load. This reduction is advantageous for mitigating the issue of significant temperature-induced secondary internal forces in the bridge pylon. Additionally, the transverse bridge stiffness of the open lower corbel cable pylon scheme is found to be on par with that of the lower continuous beam cable pylon scheme. Moreover, topology optimization of the original corbel design is accomplished using the relative density method. The computational results demonstrate that the corbel’s stress and deformation under vertical loads meet code requirements. These research findings offer valuable insights for the design and construction of similar projects.
•An automatic framework employing a hierarchical coarse-to-fine strategy designed for fine-gained pylon segmentation.•Shape prior for optimizing the fine-grained segmentation.•The MBR algorithm ...fosters pylon cross-sectional shape determination.
This paper proposes an automatic framework for pylon detection by a hierarchical coarse-to-fine segmentation of powerline corridors from UAV laser scanning point clouds. To this end, the proposed framework starts by roughly detecting the pylon location using the voxel-based height features derived from powerline corridor distribution in the vertical direction. The roughly detected pylons are then fed into the fine-grained pylon segmentation step, from which the fine-grained pylon points are learned by leveraging the shape prior knowledge. The idea behind the fine-grained is that most of the pylons can be cut horizontally into a series of rectangular cross-sections whose sizes from top to bottom are growing at a constant rate. By this linear growth relationship, the distorted cross-sections, which most commonly occur at pylon legs due to the influence of the attachments, such as trees and brush, can be accurately restored using the linear least squares regression. The performance of the proposed method was evaluated on two datasets over hilly and flat landforms. Our evaluation results showed that for powerlines in flat terrain, the proposed method achieved a precision of 99.8%, recall of 99.5%, and F1-score of 99.7%. On hilly terrain, a slightly lower performance was obtained, with a precision of 98.8%, recall of 97.8%, and F1-score of 98.3%. The proposed method’s accuracy is on par with or even better than other mainstream pylon detection algorithms.
Aircraft components can only be mounted on an aircraft if the structural integrity has been validated under flight load conditions. Among the major components of an aircraft, a pylon is a structure ...that connects external equipment such as an engine and external attachments (e.g., instruments or weapons) to the main wing of an aircraft. The loads acting on the pylon are transmitted to the main structure of the aircraft. Pylons play a key role in the requirements of aircraft structure, aerodynamics, hydraulics, and electrical systems. In civilian aircraft, pylons also play a role in preventing fire from spreading to the wings in the case of a fire near an engine. This study presents the results of structural static tests performed to validate the structural integrity of a pylon used to mount external fuel tanks and weapons in military aircraft under all loading conditions. Test requirements consisting of flight-load and drop-load conditions are explained in the main text. A test set-up diagram consisting of test fixtures, hydraulic pressure unit, load control equipment, and data acquisition equipment is presented. Moreover, the software needed to control the actuator loads is introduced and the test load profiles for each test load condition are provided. As a result of the structural static test, it is shown that the actuator loads were properly controlled within the allowable error range in each test. It was also confirmed that the behavior of the pylon was well predicted through numerical analysis by comparing the results of the numerical analysis and the structural tests of the main parts of the test specimen. Moreover, it was found that the test specimen did not cause damage or buckling, which would cause serious structural defects for the required load. In conclusion, by performing structural static tests on the design limit load and the design ultimate load, it was proved that the newly developed pylon had sufficient static strength under all load conditions during flight.
This paper presents an approach for investigating the stability performance of a three-pylons suspension bridge considering the tanker fire nearby middle steel-pylon. The proposed approach comprises ...of two steps, named as heat-transfer analysis and structural stability analysis. The first step involves the definition and simulation of fire scenarios, and the heat-transfer process from flame to the middle-pylon. The second step involves the stability performance under different fire scenarios, and the parametric study of burning time, fire area and fire location. Results show that the current fire temperature curves without considering height effects would strongly overestimate the influence of tanker fire. The stability coefficient drops significantly after 30 min and strongly dependent on the fire size and the burning location. The approach and the conclusions are of important value in the safety assessment, management, and maintenance of cable-supported bridges with steel pylons.
•Damage of the middle steel pylon under a typical tanker fire is clarified.•The structural stability under different fire scenarios is analyzed and compared.•The impact of burning time, fire size and fire location on structural stability is quantified.
The advent of deep learning provides a promising opportunity to improve the efficiency of topology optimization. However, existing methods make it difficult to achieve a balance between efficiency, ...accuracy, and generalization ability. To tackle this challenge, we propose a novel method based on a two-stage network framework. In the network, the partial convolution block and shifted windows attention mechanism are integrated to improve the model performance. In the first stage, a convolutional neural network-based model trained with a novel-designed loss function is employed to achieve real-time prediction of suboptimal structures. In the second stage, transfer learning is introduced to inherit the output of the first stage. Subsequently, the second stage optimizes the suboptimal structures to get the final optimal structures in a physical information-driven way. On the 2000 dataset, the two-stage method achieves an average compliance error of −1.45%, and 95.5% of the optimal structures perform better than that obtained by the traditional method and strictly meet volume constraints while eliminating structural disconnections. Finally, the proposed method is applied to a real-world engineering application for the first time, and the design of bridge pylons is given as an example. The results show that the proposed method is a promising exploration of topology optimization based on deep learning.
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•A two-stage framework for topology optimization based on deep learning and physical information.•Incorporated the advantages of real-time prediction, accurate optimization, and sufficient generalization capability.•Applied the proposed method to a real-word engineering application for the first time, and the bridge pylon design is given as an example.
The present study focuses on the effects of wind yaw angle and pylon interference on the buffeting responses of bridge decks during construction. Two typical cable-stayed bridges with rhombus pylons ...(RPs) and single-column pylons (SPs) in the maximum double cantilever state were selected as research objectives. The influence of the wind yaw angle and pylon interference on the lateral, vertical and torsional buffeting displacements were systematically analyzed through full bridge model aeroelastic wind tunnel tests. The research results show that the maximum buffeting responses appear when the wind yaw angle is in the range of
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The effects of the wind yaw angle on the buffeting responses become more obvious in cases of high mean wind speeds. The pylon interference effects on the lateral buffeting displacements are more significant than those on the vertical and torsional buffeting displacements. The strong pylon interference effects may lead to non-conservative buffeting response estimation results using traditional buffeting analysis methods. This study demonstrates that it is of paramount importance to take into consideration the combined effects of the wind yaw angle and pylon interference in the design of long-span cable-stayed bridges during their construction stages.
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