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学者姓名：方舟
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Abstract ：
The pulse-echo signal receiving model can effectively determine a defect's axial position through the time flight of the defect echo. However, some materials or buried structures may significantly attenuate the ultrasonic- guided wave, making the defect echo challenging to observe. Compared with the pulse-echo mode, the guided wave in the pitch-catch signal-receiving model only needs to propagate a one-way distance. Its transmitted wave is more straightforward to observe. However, the pitch-catch model is difficult to judge if a defect exists in the pitch-catch model and identify the position of a defect through the transmitted wave. The paper presents a defect-induced non-axisymmetric transmitted wave model. It can balance the advantages and disadvantages of the two signal-receiving models. First, the periodic energy distribution altering rule of the non-axisymmetric torsional guided wave within a circular tube was theoretically analyzed. Second, the numerical and experimental results verified the theoretical analysis. Third, the defect-induced non-axisymmetric transmitted wave model was proposed based on its periodic energy distribution changing rule analysis to evaluate whether a defect exists, while the traditional pitch-catch models cannot achieve it. The axial and circumferential positions of a circumferential crack within a circular tube encased in concrete can be estimated using the proposed model, which is challenging to realize by the traditional pulse-echo models.
Keyword ：
Circular tube Circular tube Defect detection Defect detection Non-axisymmetric guided wave Non-axisymmetric guided wave Pitch-catch Pitch-catch Pulse-echo Pulse-echo
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| GB/T 7714 | Chen, Shaobin , Li, Wenzhuo , Fang, Zhou . Defect induced non-axisymmetric transmitted wave model based on the periodic energy distribution changing analysis for high attenuation circular tube defect detection [J]. | APPLIED ACOUSTICS , 2025 , 232 . |
| MLA | Chen, Shaobin 等. "Defect induced non-axisymmetric transmitted wave model based on the periodic energy distribution changing analysis for high attenuation circular tube defect detection" . | APPLIED ACOUSTICS 232 (2025) . |
| APA | Chen, Shaobin , Li, Wenzhuo , Fang, Zhou . Defect induced non-axisymmetric transmitted wave model based on the periodic energy distribution changing analysis for high attenuation circular tube defect detection . | APPLIED ACOUSTICS , 2025 , 232 . |
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The position of a macrocrack within a circular tube can be determined through the periodic energy distribution variation of a linear non-axisymmetric guided wave. However, to determine the positions of a microcrack within a circular tube is still a difficult job, even for the nonlinear guided wave. Unlike the linear guided wave can detect the axial position through the reflection from a macrocrack, a fatigue crack does not even cause remarkable reflection. This paper investigates the energy concentration degree periodical variation rule of fatigue crack- induced second harmonic non-axisymmetric guided wave within a circular tube. The quantitative relationship between the energy concentration degree and its propagated axial distance is potential to be used to detect a fatigue crack and characterize its axial, circumferential positions. To facilitate the investigation, a specific frequency extracting method was optimized to extract the second harmonic non-axisymmetric guided wave. In addition, an energy concentration degree coefficient was designed to characterize the energy distribution. The fundamental, numerical and experimental work were implemented to verify the studied energy concentration degree periodical variation rule.
Keyword ：
Circular tube Circular tube Energy concentration Energy concentration Fatigue crack Fatigue crack Non-axisymmetric guided wave Non-axisymmetric guided wave Second-harmonic wave Second-harmonic wave
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| GB/T 7714 | Fang, Zhou , Lin, Conglin , Huang, Yanwei . Energy concentration degree periodical variation rule of fatigue crack-induced second harmonic non-axisymmetric guided wave within circular tubes [J]. | NDT & E INTERNATIONAL , 2025 , 151 . |
| MLA | Fang, Zhou 等. "Energy concentration degree periodical variation rule of fatigue crack-induced second harmonic non-axisymmetric guided wave within circular tubes" . | NDT & E INTERNATIONAL 151 (2025) . |
| APA | Fang, Zhou , Lin, Conglin , Huang, Yanwei . Energy concentration degree periodical variation rule of fatigue crack-induced second harmonic non-axisymmetric guided wave within circular tubes . | NDT & E INTERNATIONAL , 2025 , 151 . |
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Efficient and fair resource allocation is a critical challenge in vehicular networks, especially under high mobility and unknown channel state information (CSI). Existing works mainly focus on centralized optimization with perfect CSI or decentralized heuristics with partial CSI, which may not be practical or effective in real-world scenarios. In this paper, we propose a novel hierarchical deep reinforcement learning (HDRL) framework to address the joint channel and power allocation problem in vehicular networks with high mobility and unknown CSI. The main contributions of this work are twofold. Firstly, this paper develops a multi-agent reinforcement learning architecture that integrates both centralized training with global information and decentralized execution with local observations. The proposed architecture leverages the strengths of deep Q-networks (DQN) for discrete channel selection and deep deterministic policy gradient (DDPG) for continuous power control while learning robust and adaptive policies under time-varying channel conditions. Secondly, this paper designs efficient reward functions and training algorithms that encourage cooperation among vehicles and balance the trade-off between system throughput and individual fairness. By incorporating Jain's fairness index into the reward design and adopting a hybrid experience replay strategy, the proposed algorithm achieves a good balance between system efficiency and user equity. Extensive simulations demonstrate the superiority of the proposed HDRL method over state-of-the-art benchmarks, including DQN, DDPG, and fractional programming, in terms of both average throughput and fairness index under various realistic settings. The proposed framework provides a promising solution for intelligent and efficient resource management in future vehicular networks.
Keyword ：
Cognitive internet of vehicles Cognitive internet of vehicles Deep reinforcement learning Deep reinforcement learning Resource allocation Resource allocation Unknown channel state information Unknown channel state information
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| GB/T 7714 | Wang, Jun , Jiang, Weibin , Xu, Haodong et al. A novel resource allocation method based on hierarchical deep reinforcement learning for cognitive internet of vehicles with unknown channel state information [J]. | COMPUTER NETWORKS , 2025 , 264 . |
| MLA | Wang, Jun et al. "A novel resource allocation method based on hierarchical deep reinforcement learning for cognitive internet of vehicles with unknown channel state information" . | COMPUTER NETWORKS 264 (2025) . |
| APA | Wang, Jun , Jiang, Weibin , Xu, Haodong , Hu, Jinsong , Wu, Liang , Shu, Feng et al. A novel resource allocation method based on hierarchical deep reinforcement learning for cognitive internet of vehicles with unknown channel state information . | COMPUTER NETWORKS , 2025 , 264 . |
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The adhesive layer between an ultrasonic transducer and a circular tube can generate a nonlinear signal during guided wave excitation and reception, which is called adhesive nonlinearity (AN). It may override the damage-related signals and result in false detection if not adequately evaluated and mitigated. This study investigated the AN of the guided wave excitation model composed of a piezoelectric array in a circular tube structure. The classical shear stress lag model was extended to the circumference pasted piezoelectric array-based nonlinear shear stress lag model to investigate the coupling properties of the AN and to evaluate the AN by comparing it with other nonlinear factors within a circular tube structure. On this basis, the nonlinear shear stress was combined with the normal mode expansion to establish a frequency tuning model for the AN, which allowed the effect of the AN to be minimized by adjusting the half-wavelength of the guided wave to match the length of the actuator. Finite-element analyses and experiments validated the tuning characteristics of the AN mentioned above. This work was used to mitigate the effect of the AN on the nonlinear guided wave during thermal damage evaluation. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International (CC BY-NC-ND) license (https://creativecommons.org/licenses/by-nc-nd/4.0/).https://doi.org/10.1063/5.0243631
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| GB/T 7714 | Fang, Zhou , Lin, Zuxiong , Huang, Yanwei . Adhesive nonlinearity analysis of longitudinal guided wave using circumference pasted piezoelectric array based nonlinear shear stress lag model [J]. | JOURNAL OF APPLIED PHYSICS , 2025 , 137 (3) . |
| MLA | Fang, Zhou et al. "Adhesive nonlinearity analysis of longitudinal guided wave using circumference pasted piezoelectric array based nonlinear shear stress lag model" . | JOURNAL OF APPLIED PHYSICS 137 . 3 (2025) . |
| APA | Fang, Zhou , Lin, Zuxiong , Huang, Yanwei . Adhesive nonlinearity analysis of longitudinal guided wave using circumference pasted piezoelectric array based nonlinear shear stress lag model . | JOURNAL OF APPLIED PHYSICS , 2025 , 137 (3) . |
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Cognitive Industrial Internet of Things (CIIoT) permits Secondary Users (SUs) to use the spectrum bands owned by Primary Users (PUs) opportunistically. However, in the absence of the PUs, the selfish SUs could mislead the normal SUs to leave the spectrum bands by initiating a Primary User Emulation Attack (PUEA). In addition, the application of Energy Harvesting (EH) technology can exacerbate the threat of security. Because the energy cost of initiating a PUEA is offset to some extent by EH technology which can proactively replenish the energy of the selfish nodes. Thus, EH technology can increase the motivation of the selfish SUs to initiate a PUEA. To address the higher motivation of the selfish SUs attacking in CIIoT scenario where the EH technology is applied, in this paper, an EH-PUEA system model is first established to study the security countermeasures in this severe scenario of PUEA problems. Next, a new reward and punishment defense management mechanism is proposed, and then the dynamics of the selfish SUs and the normal SUs in a CIIoT network are studied based on Evolutionary Game Theory (EGT), and the punishment parameter is adjusted according to the dynamics of the selfish SUs to reduce the proportion of the selfish SUs’ group choosing an attack strategy, so as to increase the throughput achieved by the normal SUs’ group. Finally, the simulation results show that the proposed mechanism is superior to the conventional mechanism in terms of throughput achieved by the normal SUs’ group in CIIoT scenario with EH technology applied. IEEE
Keyword ：
Cognitive Industrial Internet of Things (CIIoT) Cognitive Industrial Internet of Things (CIIoT) Energy harvesting Energy harvesting energy harvesting (EH) energy harvesting (EH) evolutionary game theory (EGT) evolutionary game theory (EGT) Games Games Game theory Game theory Industrial Internet of Things Industrial Internet of Things Jamming Jamming primary user emulation attack (PUEA) primary user emulation attack (PUEA) Security Security Throughput Throughput
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| GB/T 7714 | Wang, J. , Pei, H. , Wang, R. et al. Defense Management Mechanism for Primary User Emulation Attack Based on Evolutionary Game in Energy Harvesting Cognitive Industrial Internet of Things [J]. | IEEE Transactions on Network and Service Management , 2024 , 21 (4) : 1-1 . |
| MLA | Wang, J. et al. "Defense Management Mechanism for Primary User Emulation Attack Based on Evolutionary Game in Energy Harvesting Cognitive Industrial Internet of Things" . | IEEE Transactions on Network and Service Management 21 . 4 (2024) : 1-1 . |
| APA | Wang, J. , Pei, H. , Wang, R. , Lin, R. , Fang, Z. , Shu, F. . Defense Management Mechanism for Primary User Emulation Attack Based on Evolutionary Game in Energy Harvesting Cognitive Industrial Internet of Things . | IEEE Transactions on Network and Service Management , 2024 , 21 (4) , 1-1 . |
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The commonly used traditional cylindroid guided wave modes are not sensitive to a crack with limited circumferential extent within a pipe. The circumferential guide wave will not be affected by the limited circumferential extent of a crack, which can be make up the limitation of the commonly used traditional cylindroid guided wave modes in crack detecting within a pipe. This article studied the spirally propagating circumferential Lamb wave within a pipe, which can determine the axial position of a crack only if the axial extent of the crack is large enough regardless the limited circumferential extent of the crack. To efficiently trigger the spirally propagating circumferential Lamb wave, the effect of the frequency, the circumferential coverage and the axial length of the transducer on the spirally propagating circumferential Lamb wave signals were investigated based on the theoretical model and experiments. Then, the comparison experiments presented the superiority of the proposed spirally propagating circumferential Lamb wave in detecting a crack with limited circumferential extent over the commonly used cylindroid guided wave mode. Finally, the angular interval of two cracks that in the same axial position can be determined through the angular interval of the triggering positions of the spirally propagating circumferential guided wave, which cannot be evaluated through the commonly used traditional cylindroid guided wave modes. © 2024 Institute of Physics Publishing. All rights reserved.
Keyword ：
circumferential extent circumferential extent Circumferential Lamb wave Circumferential Lamb wave crack detection crack detection MPT MPT spirally propagating spirally propagating
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| GB/T 7714 | Lin, Z. , Fang, Z. , Huang, Y. . Effects of transducer's Parameters on the Amplitude Response of Spirally Propagating Circumferential Lamb Wave and Their Application in Defect Detection [未知]. |
| MLA | Lin, Z. et al. "Effects of transducer's Parameters on the Amplitude Response of Spirally Propagating Circumferential Lamb Wave and Their Application in Defect Detection" [未知]. |
| APA | Lin, Z. , Fang, Z. , Huang, Y. . Effects of transducer's Parameters on the Amplitude Response of Spirally Propagating Circumferential Lamb Wave and Their Application in Defect Detection [未知]. |
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许多机械部件中的圆管结构长期在交变应力的工况下服役,容易出现疲劳裂纹,最终导致材料失效酿成事故.非线性超声能够表征疲劳裂纹的损伤程度,而表征损伤程度的非线性系数的提取方法尤为重要.提出一种基于小波变换的时频信号处理方法用以提取疲劳裂纹产生的非线性信号并以此计算非线性系数.首先,分析了多种小波基进行小波变换处理后得到的非线性系数间的量化关系;其次,利用仿真得到带有疲劳裂纹的圆管中的非线性超声导波信号,比较各类非线性系数提取方法得到的不同频率分量幅值随时间变化的信息;最后,建立疲劳裂纹损伤程度与各类方法得到的非线性系数间的量化关系.试验结果表明,所提方法得到的非线性系数能够更好地表征疲劳裂纹的损伤程度.
Keyword ：
小波变换 小波变换 有限元仿真 有限元仿真 疲劳裂纹 疲劳裂纹 非线性系数 非线性系数
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| GB/T 7714 | 林丛林 , 方舟 . 基于小波时频分析的疲劳损伤定量表征 [J]. | 无损检测 , 2024 , 46 (10) : 27-33 . |
| MLA | 林丛林 et al. "基于小波时频分析的疲劳损伤定量表征" . | 无损检测 46 . 10 (2024) : 27-33 . |
| APA | 林丛林 , 方舟 . 基于小波时频分析的疲劳损伤定量表征 . | 无损检测 , 2024 , 46 (10) , 27-33 . |
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Cognitive Industrial Internet of Things (CIIoT) permits Secondary Users (SUs) to use the spectrum bands owned by Primary Users (PUs) opportunistically. However, in the absence of the PUs, the selfish SUs could mislead the normal SUs to leave the spectrum bands by initiating a Primary User Emulation Attack (PUEA). In addition, the application of Energy Harvesting (EH) technology can exacerbate the threat of security. Because the energy cost of initiating a PUEA is offset to some extent by EH technology which can proactively replenish the energy of the selfish nodes. Thus, EH technology can increase the motivation of the selfish SUs to initiate a PUEA. To address the higher motivation of the selfish SUs attacking in CIIoT scenario where the EH technology is applied, in this paper, an EH-PUEA system model is first established to study the security countermeasures in this severe scenario of PUEA problems. Next, a new reward and punishment defense management mechanism is proposed, and then the dynamics of the selfish SUs and the normal SUs in a CIIoT network are studied based on Evolutionary Game Theory (EGT), and the punishment parameter is adjusted according to the dynamics of the selfish SUs to reduce the proportion of the selfish SUs' group choosing an attack strategy, so as to increase the throughput achieved by the normal SUs' group. Finally, the simulation results show that the proposed mechanism is superior to the conventional mechanism in terms of throughput achieved by the normal SUs' group in CIIoT scenario with EH technology applied.
Keyword ：
Cognitive industrial Internet of Things (CIIoT) Cognitive industrial Internet of Things (CIIoT) Energy harvesting Energy harvesting energy harvesting (EH) energy harvesting (EH) evolutionary game theory (EGT) evolutionary game theory (EGT) Games Games Game theory Game theory Industrial Internet of Things Industrial Internet of Things Jamming Jamming primary user emulation attack (PUEA) primary user emulation attack (PUEA) Security Security Throughput Throughput
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| GB/T 7714 | Wang, Jun , Pei, Hai , Wang, Ruiliang et al. Defense Management Mechanism for Primary User Emulation Attack Based on Evolutionary Game in Energy Harvesting Cognitive Industrial Internet of Things [J]. | IEEE TRANSACTIONS ON NETWORK AND SERVICE MANAGEMENT , 2024 , 21 (4) : 4777-4786 . |
| MLA | Wang, Jun et al. "Defense Management Mechanism for Primary User Emulation Attack Based on Evolutionary Game in Energy Harvesting Cognitive Industrial Internet of Things" . | IEEE TRANSACTIONS ON NETWORK AND SERVICE MANAGEMENT 21 . 4 (2024) : 4777-4786 . |
| APA | Wang, Jun , Pei, Hai , Wang, Ruiliang , Lin, Ruiquan , Fang, Zhou , Shu, Feng . Defense Management Mechanism for Primary User Emulation Attack Based on Evolutionary Game in Energy Harvesting Cognitive Industrial Internet of Things . | IEEE TRANSACTIONS ON NETWORK AND SERVICE MANAGEMENT , 2024 , 21 (4) , 4777-4786 . |
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An axisymmetric guided wave mode is excited independently within a circular tube structure to reduce the complexity of signal interpretation through the prevention of unwanted wave polarisations and reflections. However, it is difficult to use the axisymmetric guided wave to determine the circumferential position and coverage of a defect within the circular tube structure. Non-axisymmetric guided waves can be used to mitigate the limitation of the axisymmetric guided wave through the adoption of a partially covered transducer design and analysis of the propagation characteristics. The partial excitation of non-axisymmetric guided waves can facilitate the arrangement of a transducer during defect detection. This paper reviews state-of-the-art research on non-axisymmetric guided waves for determining the axial positions, circumferential positions, and circumferential lengths of defects. First, the fundamental analysis of a specific non-axisymmetric guided wave mode based on the normal mode expansion method and beam directivity analysis method reveals that the propagation characteristics of the wave mode are closely related to the working principle and configuration of the corresponding transducer. Then, the advantages and disadvantages of the different types of transducers and transducer arrays for the excitation of non-axisymmetric guided waves are introduced and discussed. Finally, the current defect detection methods based on non-axisymmetric guided waves are discussed and summarised. This review can promote the application of non-axisymmetric guided waves in defect detection.
Keyword ：
beam directivity analysis beam directivity analysis circular tube structure circular tube structure defect detection defect detection non-axisymmetric guided wave non-axisymmetric guided wave normal mode expansion normal mode expansion
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| GB/T 7714 | Fang, Zhou . A review of non-axisymmetric guided waves and their corresponding transducers for defect detection in circular tube structures [J]. | SMART MATERIALS AND STRUCTURES , 2023 , 32 (6) . |
| MLA | Fang, Zhou . "A review of non-axisymmetric guided waves and their corresponding transducers for defect detection in circular tube structures" . | SMART MATERIALS AND STRUCTURES 32 . 6 (2023) . |
| APA | Fang, Zhou . A review of non-axisymmetric guided waves and their corresponding transducers for defect detection in circular tube structures . | SMART MATERIALS AND STRUCTURES , 2023 , 32 (6) . |
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The ground conductor is prone to corrosion, which affects its ability to diverge current and the normal operation of the power system. The traditional detection method can't detect its corrosion degree intuitively. This paper proposes a novel method based on Electromechanical impedance (EMI) technique to evaluate the corrosion degree of the grounding conductor. Firstly, based on the analysis of corrosion of metals. The change of ground conductor radius Delta r is used as the corrosion parameter. A linear model of peak frequency Delta fm and corrosion parameter Delta r in asymmetric layout is established by analysing EMI and conductor mechanical admittance. Secondly, the EMI coupling models with different sensor layouts were built on the finite element software. It is verified that the asymmetric sensor layout effectively improves the sensitivity to corrosion. The linear model greatly improves the assessment accuracy compared with the Mean Absolute Percentage Deviation (MAPD) and Root Mean Square Deviation (RMSD) damage index. Thirdly, the proposed method is verified in a real grounding conductor corrosion experiment. The method based on the EMI technique with asymmetric sensor layout can evaluate the corrosion of the grounding conductor well.
Keyword ：
asymmetric sensor layout asymmetric sensor layout corrosion corrosion EMI EMI Grounding conductor Grounding conductor
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| GB/T 7714 | Huang, Yanwei , Chen, Yaojie , Fang, Zhou . Evaluation of ground conductor corrosion based on EMI technique with asymmetric sensor layout [J]. | NONDESTRUCTIVE TESTING AND EVALUATION , 2023 . |
| MLA | Huang, Yanwei et al. "Evaluation of ground conductor corrosion based on EMI technique with asymmetric sensor layout" . | NONDESTRUCTIVE TESTING AND EVALUATION (2023) . |
| APA | Huang, Yanwei , Chen, Yaojie , Fang, Zhou . Evaluation of ground conductor corrosion based on EMI technique with asymmetric sensor layout . | NONDESTRUCTIVE TESTING AND EVALUATION , 2023 . |
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