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Investigation of mechanical characteristics of decay-like degraded FRP rods and residual life prediction

engineering Failure Analysis 2025年 176卷

作者： Liu, Shuqi Li, Te Zuo, Zhou Tao, Ruixiang Lei, Ting Wang, Qian Wu, Chao Liang, Xidong State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Tsinghua University Beijing China State Grid Zhejiang Electric Power Co Electric Power Research Institute Huadian road Xiacheng District Zhejiang Hangzhou China

Decay-like fracture accidents have posed significant threats to the safe operation of the power transmission lines, and the time interval between the intermediate stage of decay-like degradation and final fracture remains challenging to predict. The present work investigated the residual mechanical strengths of several 500 kV composite insulators that exhibited decay-like degradation, and their degradation extent was quantified by analyzing the cross-sectional degradation areas of the fiber reinforced polymer (FRP) core rods using parallel light illumination method. A clear negative correlation was observed between the cross-sectional decay-like degradation areas and the residual mechanical strengths. Moreover, visual examination and microscopic observation of the fracture spots were conducted, and the fracture modes of different samples were classified as either decay-like fractures or splitting fractures. The macroscopic and microscopic morphologies of the fracture spot of individual sample reflected its unique fracture cause (pure mechanical fracture or stress corrosion fracture), which is directly related to the mechanical strength exhibited by the sample. Additionally, acoustic emission (AE) technique was employed during the tensile fracture test, and the signals were categorized via clustering algorithm. Finally, the correlation between the farthest heating location and the residual mechanical strength was analyzed. It was proposed that a farthest heating location exceeding the 4th large shed can significantly increase the risk of fracture for the in-service decay-like degraded composite insulators. © 2025

关键词： Fracture toughness

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Quantitative detection of alkali metal Na based on laser-induced breakdown spectroscopy technology

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Meitan Xuebao/Journal of the China Coal Society 2025年第4期50卷 2262-2270页

作者： Shen, Sijie Li, Chi Zhou, Wangzheng Wang, Zhenzhen Yan, Junjie Hou, Zongyu Wang, Zhe Deguchi, Yoshihiro School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Power System Operation and Control Tsinghua University Beijing100084 China Institute for Carbon Neutrality Tsinghua University Beijing100084 China Department of Energy and Power Engineering Tsinghua University Beijing100084 China Shanxi Research Institute for Clean Energy Tsinghua University Taiyuan030032 China Graduate School of Technology Industrial and Social Sciences Tokushima University Tokushima770-8506 Japan

The alkali metal compounds released from high alkali fuels such as low-quality coal during thermal utilization can affect the normal operation of thermal equipment. Therefore, rapid online detection of alkali metal content in low-quality coal is of great significance for controlling alkali metal release during combustion. The alkali metal Na element is used as the detection object, and the mixed samples of graphite and sodium chloride powder with different ratios are used as experimental samples. The influencing factors of measuring Na element in samples using laser induced breakdown spectroscopy (LIBS) technology are studied. The impact of two signal strength calculation methods on signal stability is compared. The influence of experimental parameters on signal strength and signal-to-noise ratio is analyzed. The quantitative calculation models for Na element have been established. Research has shown that the characteristic spectral lines of Na element, Na I 588.995 nm and Na I 589.592 nm, are suitable as the main analytical spectral lines. Using the area intensity of the dual line characteristic spectral lines of Na element as the signal intensity can effectively improve signal stability. When the laser energy is 60 mJ and the delay time is 1 000 ns, the relative standard deviation of spectral signal intensity is low and the signal-to-noise ratio is high. The quantitative calculation models are established using traditional calibration method, partial least squares (PLS) method, and support vector machine (SVR) with spectral signal intensity as the input and Na element addition in the sample as the output. The accuracy of each model is compared and analyzed. The results indicate that the PLS model may exhibit overfitting when the sample size is small and the input quantity is large. The fitting accuracy of the SVR model is 0.978 3, the root mean square percentage error of the training set is 13.42%, and the root mean square percentage error of the test set is 13.51

关键词： Sodium chloride

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Evaporation dynamics and deposition patterns of ethanol-based Al2O3 nanofluid droplets: Effects of particle sizes and substrate temperatures

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Colloids and Surfaces A: Physicochemical and engineering Aspects 2025年 719卷

作者： Wei, Youqiang Tao, Yuequn Lin, Yukai Feng, Yanhui Chu, Fuqiang School of Energy and Environmental Engineering University of Science and Technology Beijing Beijing100083 China National Key Laboratory of Spacecraft Thermal Control Beijing Institute of Spacecraft System Engineering China Academy of Space Technology Beijing100094 China National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing100190 China Department of Energy and Power Engineering Tsinghua University Beijing100084 China

The evaporation of nanofluid droplets holds significant potential for applications in thermal management. Nonetheless, the ways in which nanoparticles affect the evaporation dynamics and deposition properties of nanofluid droplets are still not well understood. Here, we investigate the effects of Al₂O₃ nanoparticle sizes and substrate temperatures on the wetting characteristics, evaporation rate, and particle deposition behavior of ethanol-Al₂O₃ nanofluid droplets. Additionally, the features and transitions of internal convective instabilities are observed and discussed. The results reveal that the addition of nanoparticles has a minor impact on the changes in wetting patterns during droplet evaporation, and all droplets evaporate in a mixed mode. Nanoparticle size plays a pivotal role in regulating deposition patterns and wetted area, which in turn indirectly affects the evaporation rate. Specifically, the heat flux at the solid-liquid interface and the evaporation rate are enhanced compared to the base fluid, with these differences becoming more pronounced at higher substrate temperatures and with larger nanoparticle sizes. The internal convection within the droplets is primarily driven by Marangoni flow, and the presence of nanoparticles has negligible influence on the flow behavior. Smaller nanoparticles tend to deposit near the center of the droplet, resulting in a reduced coffee-ring effect, whereas larger nanoparticles predominantly deposit at the contact line, forming a marked coffee ring. Therefore, by selecting nanoparticles of appropriate sizes, it is possible to enhance evaporation rates or mitigate the coffee-ring effect to meet the requirements of various industrial applications. © 2025 Elsevier B.V.

关键词： Nanoparticles

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Analysis of multi-field cavitation structure and dynamic mode decomposition based on a separated venturi cavitation generator

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European Journal of Mechanics, B/Fluids 2025年 113卷

作者： Wang, Xiaoyu Wang, Tian Ma, Junqi Sun, Qiang Lv, WanYu School of Mechanical Engineering and Automation Northeastern University Shenyang110819 China Key Laboratory of Vibration and Control of Aero-Propulsion System Ministry of Education Northeastern University Shenyang110819 China AECC Shenyang Engine Research Institute Shenyang110015 China

Cavitation is generated due to the reduction of fluid pressure, which will cause instability and erosion inside the pipeline, valve or pump etc. In this paper, based on the improved venturi cavitation generator, the cavitation under several different flow conditions is studied, and a high-speed camera is used to capture the dynamic process of cavitation at the venturi throat. The flow field simulation data have been analysed using the dynamic mode decomposition method, and the coherent structures of sheet cavitation, transition zone cavitation, and cloud cavitation and their displacements with cycle time have been investigated. The periodic variation of cavitation is analysed using a combination of experimental and numerical simulations, and the state of cavitation in the flow field is investigated in detail using data-driven tools. The results show that periodic changes in the cavitation structure can be observed intuitively through the improved venturi generator and agrees well with the results of simulation. Cavitation intensity is continuously enhanced with the increase of inlet velocity. At flow velocity of 4.68 m/s, the cavitation is manifested as a piecewise cavitation that can only be observed at the throat position, since then the length of the cavitation cloud continues to increase, finally the detachment of a bubble cloud and localized vortex cavitation are observed at velocity of 6.08 m/s. The frequency and growth characteristics of individual flow modes can be accurately captured using the dynamic modal decomposition of the flow field. © 2025

关键词： High speed cameras

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Hierarchical Path Planning and Motion control Framework Using Adaptive Scale Based Bidirectional Search and Heuristic Learning Based Predictive control

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IEEE Transactions on Vehicular Technology 2025年

作者： Du, Guodong Zou, Yuan Zhang, Xudong Li, Zirui Liu, Qi ETH Zurich Institute of Dynamic System and Control Sonneggstrasse 3 Zurich Switzerland Beijing Institute of Technology National Engineering Laboratory for Electric Vehicles School of Mechanical Engineering Beijing China Beijing Institute of Technology National Engineering Laboratory for Electric Vehicles School of Mechanical Engineering Collaborative Innovation Center of Electric Vehicles in Beijing Beijing China Delft University of Technology Department of Transport and Planning CD Delft2628 Netherlands

Autonomous vehicles have been used for a variety of driving tasks, in which path planning and motion control are important research parts to realize the autonomous driving. A hierarchical framework consisting of path planning and motion control of the vehicle for non-specific scenarios is proposed in this paper. Firstly, the description and the formulations of the problem are given, and the corresponding models are constructed. Then, the logical construction of proposed framework is expounded with several logical associations and algorithmic improvements. The bidirectional heuristic planning with adaptive scale search is designed and incorporated with robust weighted regression algorithm to plan the optimal global path, while the multi-step predictive control method based on heuristic reinforcement learning algorithm is proposed to improve the effect of the motion control. The results show that the proposed framework for autonomous driving achieves better performance in both path planning and motion control than several existing algorithms and methods. The adaptability of hierarchical framework is demonstrated. Furthermore, the effectiveness of the hierarchical framework in real world scenario application is also validated. © 1967-2012 IEEE.

关键词： Predictive control systems

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Optimal Design and Seismic Performance of Base-Isolated Structures with Varying Heights Equipped with Tuned Inerter Dampers Subjected to Far-Fault and Near-Fault Ground Motions

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Applied Sciences (Switzerland) 2025年第9期15卷 4739-4739页

作者： Kang, Yingjie Zhang, Zewen Zhang, Zeyu Zhang, Xinyu Liu, Qingkuan Key Laboratory of Roads and Railway Engineering Safety Control Shijiazhuang Tiedao University Ministry of Education Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

This paper investigates the optimal design of base-isolated structures equipped with tuned inerter dampers (TIDs) subjected to various ground motions. The Clough–Penzien model is employed to simulate the power spectrum of three types of ground motions: far-fault, near-fault without pulse subset, and near-fault with pulse subset, with the relevant parameters identified based on actual ground motions. The optimal parameters of the TID for base-isolated structures are determined using the H2 optimization criterion to reduce the structural displacement response. The impact of relevant design properties about the optimal parameters is analyzed. The seismic control effectiveness of the TID for 5-storey, 10-storey, and 15-storey base-isolated structures with varying heights is then evaluated through time history analysis, considering far-fault, near-fault without pulse subset, and near-fault with pulse subset ground motions. The main conclusions of this study are as follows: the ground motion type, the natural vibration period of the isolated structure, the damping ratio of the isolated structure and the mass ratio of the TID all affect the optimal parameters and should be analyzed based on specific circumstances. The control effectiveness of the TID on displacement and acceleration response is more pronounced under far-fault ground motion than under near-fault ground motion. The TID equipped in the isolation storey exhibits considerable effectiveness in controlling the seismic response of 5-storey and 10-storey base isolated structures, while it exhibits weaker control over the seismic response of the 15-storey structure. Additionally, while the TID primarily targets displacement response control, it also exhibits substantial control over the absolute acceleration response of the structure. © 2025 by the authors.

关键词： Seismic design

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Shape Embedding and Knowledge Mining Network for Generalized Few-Shot Remote Sensing Segmentation

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IEEE Geoscience and Remote Sensing Letters 2025年 22卷

作者： Qiu, Zifeng Liu, Hongyu Xiong, Hang Di, Chengliang Fang, Hao Cong, Runmin Beijing Jiaotong University Institute of Information Science Beijing100044 China The54th Research Institute of CETC Shijiazhuang050081 China China Communication System Co. Ltd. Hebei Branch Shijiazhuang050081 China Shandong University School of Control Science and Engineering Jinan250061 China Ministry of Education Key Laboratory of Machine Intelligence and System Control Jinan250061 China Beijing Key Laboratory of Advanced Information Science and Network Technology Beijing100044 China

In recent years, generalized few-shot segmentation (GFSS) has received widespread attention from scholars by virtue of its superiority in low-data regimes. Most of the existing research focuses on natural image processing, and few studies have been devoted to the practical but challenging topic of remote sensing image (RSI) understanding. In this paper, we propose a Shape Embedding and Knowledge Mining Network (SKNet) for generalized few-shot RSI segmentation. Specifically, the framework is divided into two key stages: (a) In the base class learning stage, shape representation embedding is introduced to enhance the network's ability to perceive remote sensing objects. Simultaneously, we introduce the self-reconstruction constraint to prevent new unseen classes from merging, thereby improving the representation uniqueness of these classes. (b) In the novel class learning stage, a base class knowledge mining mechanism is designed to update the prototypes of the novel class by using the prototype representation of the base class, so as to enhance the discrimination ability of the network. We validated our methods on the adapted version of OpenEarthMap and iSAID datasets. In comparison with existing GFSS methods, the proposed approach demonstrates an advancement. © 2004-2012 IEEE.

关键词： Semantic Segmentation

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Bismuth oxide based composite cathode for the intermediate temperature barrier layer free solid oxide fuel cell

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International Journal of Hydrogen Energy 2025年 141卷 13-23页

作者： Xiaoyu Wang Yongliang Zhang Tatsuya Kawada Minfang Han Fuel Cell and Energy Storage Innovation Research Center Department of Energy and Power Engineering State Key Laboratory of Power System Operation and Control Tsinghua University Beijing 100084 PR China Graduate School of Environmental Studies Tohoku University Sendai 980-8579 Japan

The high cost and low reliability caused by the high operation temperature hinder the further commercialization of the solid oxide fuel cell (SOFC) at this stage. Thus, lowering the operation temperature and simplifying the structure of the SOFC are both considered to be effective solutions to solve the current issues. Here, the design, fabrication and actual effect of the La 0 · 8 Sr 0 · 2 MnO 3 -(Bi 0 · 75 Y 0.25 ) 0.93 Ce 0 · 07 O 1.5±δ (LSM-BYC) cathode and La 0 · 8 Sr 0 · 2 MnO 3 @(Bi 0 · 75 Y 0.25 ) 0.93 Ce 0 · 07 O 1.5±δ (LSM@BYC) cathode used for the intermediate temperature barrier layer free SOFC are reported. The results showed that tight interfaces between the abovementioned two composite cathodes and the Y 0 · 16 Zr 0 · 84 O 2-δ (YSZ) electrolyte can be formed by sintering at 800 °C. The higher oxygen ion conductivity and oxygen reaction activity of the LSM-BYC cathode and the LSM@BYC cathode, and much simplified structure of the barrier layer free SOFC all contributed to lowering the ohmic resistance and the polarization resistance, making barrier layer free SOFCs used LSM-BYC cathode and LSM@BYC cathode showed better electrochemical performances at intermediate operation temperature 650 °C from low oxygen partial pressure atmosphere to pure oxygen atmosphere, particularly the latter. What is more, the intermediate temperature barrier layer free SOFC used the LSM-BYC cathode showed better operation stability without obvious activation and degradation during the constant electric current generation over one hundred hours. But the deterioration of the interface between the LSM@BYC cathode and the YSZ electrolyte during the operation was likely to cause the sharp decrease of the electrochemical performance, the solutions of which still need further exploration.

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Performance-Aware control of Modular Batteries For Fast Frequency Response

arXiv

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arXiv 2025年

作者： He, Yutong Ruan, Guangchun Zhong, Haiwang State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Tsinghua University Beijing100084 China Lab for Information and Decision Systems Massachusetts Institute of Technology CambridgeMA02139 United States

Modular batteries can be aggregated to deliver frequency regulation services for power grids. Although utilizing the idle capacity of battery modules is financially attractive, it remains challenging to consider the heterogeneous module-level characteristics such as dynamic operational efficiencies and battery degradation. In addition, real-time decision making within seconds is required to enable fast frequency response. In order to address these issues, this paper proposes a performance-aware scheduling approach for battery modules to deliver fast frequency response (FFR) support. In particular, the conduction loss and switching loss of battery packs as well as converters are captured within a mix-integer quadratic constrained program (MIQCP). The cycle-based aging model identifies the aging cost of battery modules during frequent cycling by introducing the aging subgradient calculation and linearization. Case studies based on real-world battery data show that the proposed scheduling approach can effectively reduce power loss cost by nearly 28%-57% and battery aging cost by 4%-15% compared to conventional methods, which can also enhance the SoC balance. Copyright © 2025, The Authors. All rights reserved.

关键词： Battery management systems

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Aerodynamic reconstruction of wind turbines using terrestrial laser scanning: Methodology, validation, and error analysis

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Energy Conversion and Management 2025年 334卷

作者： Xie, Zhen Lin, Zhongwei Cai, Qinlin Chen, Zhenyu State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources School of Control and Computer Engineering North China Electric Power University Beijing102206 China China Huaneng Group Co. Ltd. Beijing100031 China

Aerodynamic performance analysis is essential for improving wind turbine efficiency and reliability, yet it is often constrained by the lack of aerodynamic models, either due to commercial confidentiality or the legacy turbine types. This study proposes a novel method for aerodynamic reconstruction of wind turbines using Terrestrial Laser Scanning (TLS). The method allows for efficiently capturing turbine geometry and aerodynamic properties without requiring blade disassembly. The specific procedures, including TLS-based data acquisition, data preprocessing, and blade parameterization, are outlined systematically to demonstrate the complete framework. A field implementation on a 2 MW commercial wind turbine proved its effectiveness, with validation against historical data and manufacturer-supplied performance curves showing strong consistency. Challenges such as blade twist variations and wind speed measurement inaccuracies are analyzed as potential error sources, and strategies for enhancing precision and reliability are provided. The proposed method offers a competitive, engineering-oriented solution for wind turbine aerodynamic reconstruction, laying a foundation for enhanced turbine design, operational efficiency, and long-term performance optimization. © 2025 Elsevier Ltd

关键词： Laser applications

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