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A More Accurate Reconstruction Method for Detecting Large-Depth Defects in Plates Using SH Guided Waves

Acta Mechanica Solida Sinica 2021年第2期34卷 174-183页

作者： yihui da Qi Li Bin Wang Dianzi Liu Zhenghua Qian State Key Laboratory of Mechanics and Control of Mechanical Structures College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing210016China School of Engineering University of East AngliaNorwich NR47TJUK

The inspection of thickness thinning defects and corrosion defects is greatly significant for the health prediction of plate *** main aim of this research is to propose a novel and effective approach to achieve the accurate and rapid detection of arbitrary defects using shear horizontal(SH)guided waves,particularly for large-depth and complex *** proposed approach combines the quantitative detection of Fourier transform with a reference model-based strategy to improve the accuracy of large-depth defect *** the shallow defect profile is theoretically constructed by inverse Fourier transform of the product of reflection coefficients and integral coefficients of reference models,the unknown large-depth defect can be initially assessed using the relevant information from a predefined reference *** iteratively updating the integral coefficients of reference models,the accuracy of reconstruction of large-depth defects is much *** achieve the converged defect profile,a termination criterion,the root mean square error,is applied to guarantee the construction of defects with a high level of ***,the hybrid finite element method is used to simulate the propagation of SH guided waves in plates for calculating the reflection coefficients of plates with ***,to demonstrate the capability of the developed reconstruction method for defect detection in terms of accuracy and efficiency,three types of large-depth defect profiles,i.e.,a rectangular flaw,a double-rectangular flaw and a complex flaw,are *** show that the discrepancy between the predicted defect profile and the real one is quite small,even in the largest-depth defect case where the defect depth is equal to 0.733 times the plate thickness,the minimal difference is *** is noted that the fast convergence of the proposed approach can be achieved by no more than ten updates for the worst case.

关键词： Large-depth defect SH guided wave Iterative strategy Reference model Hybrid FEM

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An analytical approach to reconstruction of axisymmetric defects in pipelines using T(0,1)guided waves

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Applied Mathematics and Mechanics(English Edition) 2020年第10期41卷 1479-1492页

作者： yihui da Bin WANG D.Z.LIU Zhenghua QIAN State Key Laboratory of Mechanics and Control of Mechanical Structures College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China School of Engineering University of East AngliaNorwich NR47TJU.K

Torsional guided waves have been widely utilized to inspect the surface corrosion in pipelines due to their simple displacement behaviors and the ability of longrange ***,the torsional mode T(0,1),which is the first order of torsional guided waves,plays the irreplaceable position and role,mainly because of its non-dispersion characteristic ***,one of the most pressing challenges faced in modern quality inspection is to detect the surface defects in pipelines with a high level of *** into account this situation,a quantitative reconstruction method using the torsional guided wave T(0,1)is proposed in this *** methodology for defect reconstruction consists of three ***,the reflection coefficients of the guided wave T(0,1)scattered by different sizes of axisymmetric defects are calculated using the developed hybrid finite element method(HFEM).Then,applying the boundary integral equation(BIE)and Born approximation,the Fourier transform of the surface defect profile can be analytically derived as the correlative product of reflection coefficients of the torsional guided wave T(0,1)and the fundamental solution of the intact pipeline in the frequency ***,reconstruction of defects is precisely performed by the inverse Fourier transform of the product in the frequency *** experiments show that the proposed approach is suitable for the detection of surface defects with arbitrary ***,the effects of the depth and width of surface defects on the accuracy of defect reconstruction are *** is noted that the reconstructive error is less than 10%,providing that the defect depth is no more than one half of the pipe thickness.

关键词： torsional guided wave hybrid finite element method(HFEM) boundary integral equation(BIE) quantitative reconstruction

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一种基于深度学习的超声导波缺陷重构方法

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固体力学学报 2021年第1期42卷 33-44页

作者：李奇笪益辉王彬蒋浩 Dianzi Liu 钱征华南京航空航天大学机械结构力学及控制国家重点实验室航空学院南京210016 南京玻璃纤维研究设计院有限公司标准认证技术研究院评价研究所南京210012 School of Engineering University of East Anglia UK

超声导波检测因其传播效率高、耗能少等优势成为了无损检测领域的重要研究方向.目前已有的利用超声导波进行结构缺陷探测和定量化重构的方法主要由相关的导波散射理论推导得出.然而,由于导波散射问题本身的高复杂性,使得在推导上述理论... 详细信息

超声导波检测因其传播效率高、耗能少等优势成为了无损检测领域的重要研究方向.目前已有的利用超声导波进行结构缺陷探测和定量化重构的方法主要由相关的导波散射理论推导得出.然而,由于导波散射问题本身的高复杂性,使得在推导上述理论方法时引入一些近似假设,降低了重构结果的质量.另外,有些方法通过优化迭代的方式提高重构精度,又会增加检测的时间成本.有鉴于此,论文探索了一种将卷积神经网络与导波散射理论模型以局部融合的方式实现缺陷定量化重构的新方法.应用样本数据训练后的神经网络实现缺陷定量化重构,弥补缺陷重构过程中的理论模型误差,同时去除在实际检测过程中所存在的环境噪声.论文以利用SH导波重构平板中的减薄缺陷为研究对象,通过数值模拟验证了该方法在缺陷重构时具有高效率和高精度的特点,特别是对矩形缺陷的重构,新方法的结果精度比波数空间域变换法的精度提高了近200%.

关键词：超声波检测深度学习卷积神经网络缺陷重构

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K-Corruption Intermittent Attacks for Violating the Codiagnosability

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IEEE/CAA Journal of Automatica Sinica 2025年第1期 159-172页

作者： Ruotian Liu yihui Hu Agostino Marcello Mangini Maria Pia Fanti IEEE the Department of Electrical and Information Engineering Polytechnic University of Bari the School of Automation Xi'an University of Posts and Telecommunications

In this work, we address the codiagnosability analysis problem of a networked discrete event system under malicious attacks. The considered system is modeled by a labeled Petri net and is monitored by a series of sites, in which each site possesses its own set of sensors, without requiring communication among sites or to any coordinators. A net is said to be codiagnosable with respect to a fault if at least one site could deduce the occurrence of this fault within finite steps. In this context, we focus on a type of malicious attack that is called stealthy intermittent replacement attack. The stealthiness demands that the corrupted observations should be consistent with the system's normal behavior, while the intermittent replacement setting entails that the replaced transition labels must be recovered within a bounded of consecutive corrupted observations(called as K-corruption intermittent attack). Particularly, there exists a coordination between attackers that are separately effected on different sites, which holds the same corrupted observation for each common transition under attacks. From an attacker viewpoint, this work aims to design Kcorruption intermittent attacks for violating the codiagnosability of systems. For this purpose, we propose an attack automaton to analyze K-corruption intermittent attack for each site, and build a new structure called complete attack graph that is used to analyze all the potential attacked paths. Finally, an algorithm is inferred to obtain the K-corruption intermittent attacks, and examples are given to show the proposed attack strategy.

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A design and manufacturing methodology for encoded soft-textile robots

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 212-213页

作者： yihui Zhang Applied Mechanics Laboratory Department of Engineering MechanicsTsinghua UniversityBeijing 100084China

The development of programmable soft robots with bioinspired morphing capabilities has attracted considerable *** mode and complexity of morphing capabilities are essential to the manipulation and movement abilities o... 详细信息

关键词： environments robots manipulation

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New insights on driving factors of East Asian droughts and floods

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Science China Earth Sciences 2024年第12期67卷 3957-3959页

作者： yihui DING National Climate Center China Meteorological AdministrationBeijing 100081China

*** As one of the most densely populated regions in the world,East Asia suffers significant socioeconomic impacts from extreme events such as heatwaves,floods,and tropical *** instance,in July 2021,Henan province was struck by a record-breaking rainstorm,with Zhengzhou experiencing unusual precipitation intensities reaching 201.9 mm per hour.

关键词： floods driving breaking

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Relative humidity and temperature dependence of mechanical degradation of natural fiber composites^(?)

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Science China(Physics,Mechanics & Astronomy) 2016年第6期59卷 68-76页

作者： yihui Pan Zheng Zhong School of Aerospace Engineering and Applied Mechanics Tongji University

In this paper,the mechanical degradation of natural fiber composites is studied with the consideration of the relative humidity and the temperature.A nonlinear constitutive model is established,which employs an internal variable to describe the mechanical degradation related to the energy dissipation during moisture *** existing experimental researches demonstrated that the mechanical degradation is an irreversible thermodynamic process induced by the degradation of fibers and the damages of interfaces between fiber and matrix,both of which depend on the variation of the relative humidity or the *** evolution of the mechanical degradation is obtained through the determination of dissipation rates as a function of the relative humidity and the *** theoretically predicted mechanical degradations are compared with experimental results of sisal fiber reinforced composites subject to different relative humidity and temperatures,and a good agreement is found.

关键词： natural fiber moisture absorption mechanical degradation relative humidity temperature

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Editorial for the Special Issue on"Origami/Kirigami Structures and Engineering Applications"

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Acta Mechanica Solida Sinica 2023年第4期36卷 477-478页

作者： yihui Zhang Ke Liu Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China Department Advanced Manufacturing and Robotics Peking UniversityBeijing 100871China

Origami and kirigami structures originate from the ancient art of paper folding and *** offer the opportunity to achieve superior performances and unusual function-alities brought by complex three-dimensional geometri... 详细信息

关键词： unusual function Issue

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DETERMINATION OF FRACTURE TOUGHNESS OF BRITTLE MATERIALS BY INDENTATION

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Acta Mechanica Solida Sinica 2015年第3期28卷 221-234页

作者： yihui Feng Taihua Zhang State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences College of Mechanical Engineering Zhejiang University of Technology

Fracture toughness is one of the crucial mechanical properties of brittle materials such as glasses and ceramics which demonstrate catastrophic failure modes. Conventional stan- dardized testing methods adopted for fracture toughness determination require large specimens to satisfy the plane strain condition. As for small specimens, indentation is a popular, sometimes exclusive testing mode to determine fracture toughness for it can be performed on a small flat area of the specimen surface. This review focuses on the development of indentation fracture theories and the representative testing methods. Cracking pattern dependent on indenter geometry and material property plays an important role in modeling, and is the main reason for the diversity of indentation fracture theories and testing methods. Along with the simplicity of specimen require- ment is the complexity of modeling and analysis which accounts for the semi-empirical features of indentation fracture tests. Some unresolved issues shaping the gap between indentation fracture tests and standardization are also discussed.

关键词： indentation fracture toughness indenter geometry cracking patterns

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Editorial

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Journal of Meteorological Research 2014年第5期28卷 669-670页

作者： DING yihui WU Guoxiong da-Lin ZHANG ZHANG Renhe 1. National Climate Center Beijing China2. Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China3. Department of Atmospheric and Oceanic Science University of Maryland College Park USA4. Chinese Academy of Meteorological Sciences Beijing China

As we will soon celebrate the 90th anniversary of the founding of the Chinese Meteorological Society （CMS）,Acta Meteorologica Sinica （AMS）,which was originally named as Bulletin of the Chinese Meteorological Society,has gone through 89 years of development and excitement since her first issue in July *** to archived documents （CMS Editorial Committee,1925）,AMS was founded to report the research findings of Chinese meteorologists,record their recommendations for improving meteorological services,and share their common meteorological interests in order to promote the growth of AMS such that more members could be inspired to conduct atmospheric research and meteorological knowledge would be better disseminated to and benefit the general *** upholding and carrying forward this purpose,AMS has published many highly valuable scientific *** could be treated as classical articles,which have produced important influences on both domestic and international meteorological communities and the related fields.

关键词： As Editorial AMS

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