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Using a single sensor for bridge condition monitoring via moving embedded principal component analysis

STRUCTURAL HEALTH MONITORING-AN INTERNATIONAL JOURNAL 2021年第6期20卷 3123-3149页

作者： Nie, Zhenhua Shen, Zhaofeng Li, Jun Hao, Hong Lin, Yizhou Ma, Hongwei Jiang, Hui Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Guangdong Peoples R China Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China Curtin Univ Sch Civil & Mech Engn Ctr Infrastruct Monitoring & Protect Bentley WA Australia Dongguan Univ Technol Dongguan Peoples R China Shenzhen Acad Disaster Prevent & Reduct Shenzhen Peoples R China

This article presents a novel data-driven structural damage detection method named moving embedded principal component analysis to monitor the bridge condition and detect the damage occurrence using only one sensor. A fixed moving window is used to cut out the time series of the recorded data for the analysis. The data set inside the window is embedded to be a multidimensional state space using time delay method. The matrix of the state space is analyzed using the standard principal component analysis method, and a novel damage index R-j defined with the eigenvalue is proposed to identify structural damage occurrence. The window length is determined by a new approach through examining the convergent spectrum of the contribution ratio of the first principal component of the embedded state space. The time delay is determined by the autocorrelation function of the response, and the embedding dimension is obtained by the cumulative contribution ratio of the state space. The windowed damage index can be calculated continuously by moving the window along the recorded vibration data. To demonstrate the performance of the proposed method, responses of a beam bridge model subjected to stochastic loads obtained with numerical simulations and experimental tests are analyzed to monitor the structural conditions. The results demonstrate that the proposed method can accurately identify the occurrence of damage and the abnormal behavior of the structure. The recorded data on a large suspension bridge are also analyzed. The analysis successfully identified an incident on this bridge when it was slightly scraped by the mast of a sand ship. This further verifies the effectiveness of the proposed method.

关键词： Structural health monitoring condition monitoring damage detection moving embedded principal component analysis single sensor

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A compact double-layer wideband circularly polarized microstrip antenna with parasitic elements

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INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED engineering 2021年第1期31卷 e22471-e22471页

作者： Su, Wei Li, Junkui Liu, Ren-Huai Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China China Elect Prod Reliabil & Environm Testing Res Sci & Technol Reliabil Phys & Applicat Technol El Guangzhou Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou Peoples R China

In this article, a new broadband circularly polarized (CP) microstrip patch antenna (MPA) with a sequential phase (SP) square-loop feeding structure is proposed. The presented antenna is composed of a square-loop feeding structure, four L-shaped parasitic patches with L-shaped slots, four parasitic square patches, and a corner-truncated square patch. At first, a SP square-loop is designed as a feeding structure. Then, four L-shaped parasitic patches with L-shaped slots are utilized to generate one CP mode by a capacitive coupled way. At last, four parasitic square patches and a corner-truncated square patch are together placed above the SP feeding structure to broaden the circularly polarized bandwidth (CPBW). The presented antenna has a wide 3-dB axial ratio bandwidth (ARBW) of 16.7% (5.4 GHz, 4.95-5.85 GHz), and a wide 10-dB return loss bandwidth of 25.5% (5.5 GHz, 4.8-6.2 GHz). The proposed antenna features compact structure and broad 3-AR bandwidth which could completely cover the WLAN (5.725-5.85GHz) band. Therefore, the proposed antenna is suitable for circular polarization applications in C band.

关键词： circularly polarized antenna sequential phase parasitic elements wideband antenna

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Behavior of confined concrete with recycled glass fiber-reinforced polymer needles as coarse aggregates under axial compression

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JOURNAL OF BUILDING engineering 2023年 71卷

作者： Cheng, Cai-Shu Xu, Yuan-Bin Xiao, Cong-Yue Fu, Bing Gao, Ruo-Fan Kuang, You-Di Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Wuyi Univ Sch Civil Engn & Architecture Jiangmen 529020 Peoples R China

Cutting waste GFRP into needles as part of coarse aggregates in concrete shows to be a promising approach for recycling the waste GFRP composites. However, the resulting concrete has its compressive strength lower than that of normal concrete, and is therefore limited for use in nonstructural elements. The present study proposes a method to improve the robustness of such concrete in structural elements by utilizing the confined concrete concept, in which the concrete with GFRP needles is confined with carbon fiber-reinforced polymer wraps. A series of compression tests under concentric loading were conducted with the ratio of GFRP needles to the total coarse aggregates (i.e., replacement ratio) and the confining jacket stiffness as the two test parameters. The test results indicate that the compressive strength of unconfined concrete decreased by approximately 10% due to replacing 15% coarse aggregates with GFRP needles, while the confining jackets of the same stiffness applied resulted the compressive performance of the confined concrete with needles comparable to or even slightly higher than that of its counterpart without needles. Two widely-used theoretical models were used to predict the compressive performance of the confined concrete, finding that both of them overestimated the axial stress but underestimated the axial strain of the confined concrete with GFRP needles. Therefore, a refined model is required to predict the behavior of confined concrete with GFRP needles under axial compression.

关键词： Recycling Glass fiber-reinforced polymer (GFRP) needles Carbon fiber-reinforced polymer (CFRP) Confined concrete Compressive behavior

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Molecular mechanics mechanisms for ultralow bending stiffness of monolayer silicene

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MATERIALS TODAY COMMUNICATIONS 2022年 33卷

作者： Yang, Mengyu Kuang, Youdi Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China Wuyi Univ Sch Civil Engn & Architecture Jiangmen Peoples R China

Monolayer silicene, as one-atom thick membrane, has a bending stiffness of about 0.31 eV, even much lower than that of monolayer graphene for which only weak out-of-plane p-bonding interactions contribute to the elastic constant. To clarify the underlying mechanisms, we explore the origin of bending stiffness for silicene from the viewpoint of molecular mechanics. An approach to achieve high precision atomic interaction potential parameters are developed by combining independent deformation modes of lattices with quantum mechanical calculations. For comparison, the corresponding studies are also conducted for graphane and graphene. It is found that, different with the out-of-plane p-bonding interactions for graphene, the bending stiffness of silicene and graphane origins from the covalent angle interactions, the covalent bond interactions contribute little to their bending stiffness. The reasons for the significant discrepancy of bending stiffness value between these monolayers are clarified by means of the quantitative comparison of atomic interaction strength. Present work has a general implication in understanding nanomechanics of one atom thick monolayers.

关键词： Ultrathin monolayer Quantum mechanics calculations Lattice dynamics calculations Molecular mechanics mechanism Origin of bending stiffness

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Numerical Simulation of Harmonic Response Analysis for Small Out-Line Package

Numerical Simulation of Harmonic Response Analysis for Small...

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Software engineering, Social Network Analysis and Intelligent Computing (SSAIC), Asia-Pacific Conference on

作者： Hai Lin Xianshan Dong Wei Su Qinwen Huang Agam Tomar School of Mechanics and Construction Engineering Jinan University Guangzhou China Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou China Faculty of Engineering and Mathematical Sciences University of Western Australia Australia

ISBN: (数字)9798350393682

ISBN: (纸本)9798350393699

In order to discuss the influence of the number of sheets on acceleration and frequency curve of sample surface, the finite element model of clamp, SOP sample and metal sheet is firstly established with Solidworks. Different number of sheets are laid on the surface of SOP sample. Then changing the number of the paper sheets, harmonic response analysis is converted based on modal analysis. The influence of different number of sheet on acceleration and frequency curve is discussed. The results show the relation between acceleration-frequency curve of different thickness of paper, which provides reference for packaging design.

关键词： Solid modeling Social networking (online) Modal analysis Metals Packaging Harmonic analysis Numerical simulation

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Application of MobilenetV3-Large model improved by transfer learning and CBAM Module in crack recognition and classification 10

Application of MobilenetV3-Large model improved by transfer ...

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10th Australasian Congress on Applied Mechanics, ACAM 2021

作者： Chen, Liujie Yao, Haodong Ng, Ching Tai Fu, Jiyang School of Civil Engineering Guangzhou University Guangdong Guangzhou China MOE Key Lab of Disaster Forecast and Control in Engineering Guangdong Guangzhou China School of Civil Environmental & Mining Engineering The University of Adelaide SA Australia Research Center for Wind Engineering and Engineering vibration Guangzhou University Guangdong Guangzhou China

ISBN: (纸本)9781925627596

Crack is an important indication for assessing the condition and safety of concrete structures. Quick and accurate crack feature extraction and classification performance of deep learning model are important in crack classification. Therefore, this study proposed a crack classification method based on the modified lightweight neural network. The proposed method uses MobileNetV3-Large pre-trained using an ImageNet dataset as backbone and then adopts the Convolution Block Attention Module (CBAM), which contains two modules, Channel Attention Module and Spatial Attention Module. Without increasing the number of model parameters, CBAM can strengthen the ability of the neural network in crack feature extraction. The image dataset of concrete structures for verifying the proposed method contains four different types of cracks: transverse cracks, vertical cracks, diagonal cracks, and irregular cracks. Other deep learning models, such as MobileNetV3-Large, VGG16, EfficentNetB0, GoogLeNet, Efficentnetv2-S, are also used for the crack classification in this study and the results are compared with those obtained by the proposed method. The results demonstrate that the proposed method has the best performance with the minimum training time at 100 images/s and prediction time at 47.6 images/s, Accuracy of 95.93%, Precision of 95.95%, Recall of 95.95%, and Macro-F1 of 96.20%. The results indicate that the proposed method can effectively improve the accuracy of crack recognition and classification. It can also strengthen the ability of the network in extracting the complex crack image features. The proposed method can be applied practically for automatic crack detection. © ACAM 2021. All rights reserved.

关键词： Concrete buildings

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The Enhancing Effect of the East Asian Subtropical Westerly Jet on Summer Extreme High-Temperature Events over Central-Eastern China Since the Late 1990s

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Advances in Atmospheric Sciences 2025年第3期42卷 453-466页

作者： Chujie GAO Yuyu NIU Gen LI Shanlei SUN Bo LU Chaofan LI Bei XU Jinglong HUANG Xiubao SUN College of Oceanography&Key Laboratory of Marine Hazards Forecasting Ministry of Natural ResourcesHohai UniversityNanjing 210098China Key Laboratory of Meteorological Disaster Ministry of Education(KLME)&Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science and TechnologyNanjing 210044China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Laboratory for Climate Studies and CMA-NJU Joint Laboratory for Climate Prediction Studies National Climate CenterChina Meteorological AdministrationBeijing 100081China Xiong’an Institute of Meteorological Artificial Intellegence Xiong'an 071708China Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of the Chinese Academy of SciencesBeijing 100049China College of Intelligent Science and Control Engineering Jinling Institute of TechnologyNanjing 211169China

The increase in frequency and intensity of Extreme High-temperature Events(EHEs)over Central-Eastern China(CEC)in recent decades has severely impacted social development and *** observation and reanalysis datasets,this study explores the effect of the East Asian subtropical westerly jet stream(EAJ)on the CEC EHEs for the summers spanning 1979–*** its general relative location to the right side of the upper-level jet stream exit region,CEC would theoretically suffer more EHEs with a stronger and northwardly-shifted EAJ in summer due to the likelihood of abnormal subsidence induced by the ***,such an EAJ–EHE connection has been unstable over the past four decades but has displayed an evident interdecadal *** the late 1990s,the interannual variation of the EAJ was manifested mainly by its meridional displacement in the northeastern part of East Asia;thus,the atmospheric responses were essentially located to the east of CEC,exerting less of an influence on the CEC ***,since the late 1990s,the EAJ variation has featured an intensity change in its center over the northwest portion of the CEC,which has resulted in a westward shift in atmospheric responses to cover the CEC ***,the EAJ could potentially affect the summer CEC EHEs during 2000–*** findings offer support for an in-depth understanding of the formation mechanisms of extreme weather/climate events of this nature and thus provide a scientific reference for seasonal climate predictions.

关键词： summer extreme high-temperature events East Asian subtropical jet atmospheric circulation central-eastern China interdecadal change

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Regularization Strategies for Contiguous and Noncontiguous Damage Detection of Structures

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INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS 2021年第6期18卷

作者： Luo, Ziwei Yu, Ling Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China

Regularization strategies have attracted attention in the structural damage detection (SDD) field. However, there is lack of studies on regularization strategies for damage patterns in the existing methods. This paper proposes regularization strategies for contiguous and noncontiguous damages of structures and performs comparative studies. The objective functions are first defined to consider effects of strategies on SDD by adding distinct norm penalties, and then are solved by the particle swarm optimization (PSO). Three numerical simulation models are employed to assess the applicability of three strategies. The results show that the l(2) norm regularization is suitable for detecting multiple damages, the l(1) norm regularization performs well in contiguous damages, and the sparsest solutions can be obtained by the l(1/2) norm regularization.

关键词： Structural damage detection (SDD) regularization strategy norm penalty sensitivity analysis particle swarm optimization (PSO)

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Screws Fixation for Oblique Lateral Lumbar Interbody Fusion (OL-LIF): A Finite Element Study

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BIOMED RESEARCH INTERNATIONAL 2021年第0期2021卷 000-000页

作者： Ling, Qinjie Zhang, Huanliang He, Erxing Guangzhou Med Univ Dept Spinal Surg Affiliated Hosp 1 151 Yanjiang West Rd Guangzhou 510120 Guangdong Peoples R China Jinan Univ Inst Appl Mech MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

Background. The combination of screw fixation and cage can provide stability in lumbar interbody fusion (LIF), which is an important technique to treat lumbar degeneration diseases. As the narrow surface cage is developed in oblique lateral lumbar interbody fusion (OL-LIF), screw fixation should be improved at the same time. We used the finite element (FE) method to investigate the biomechanics response by three different ways of screw fixation in OL-LIF. Methods. Using a validated FE model, OL-LIF with 3 different screw fixations was simulated, including percutaneous transverterbral screw (PTVS) fixation, percutaneous cortical bone trajectory screw (PCBTS) fixation, and percutaneous transpedical screw (PPS) fixation. Range of motion (ROM), vertebral body displacement, cage displacement, cage stress, cortical bone stress, and screw stress were compared. Results. ROM in FE models significantly decreased by 84-89% in flexion, 91-93% in extension, 78-89% in right and left lateral bending, and 73-82% in right and left axial rotation compared to the original model. The maximum displacement of the vertebral body and the cage in six motions except for the extension of model PTVS was the smallest among models. Meanwhile, the model PTVS had the higher stress of screw-rods system and also the lowest stress of cage. In all moments, the maximum stresses of the cages were lower than their yield stress. Conclusions. Three screw fixations can highly restrict the surgical functional spinal unit (FSU). PTVS provided the better stability than the other two screw fixations. It may be a good choice for OL-LIF.

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The Effects of RF Power and Cavity Structure on the Plasma Discharge Characteristics of RPS

The Effects of RF Power and Cavity Structure on the Plasma D...

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Electronics and Devices, Computational Science (ICEDCS), International Conference on

作者： Hai Lin Wei Su Ming Chen Renhuai Liu School of Mechanics and Construction Engineering Jinan University Guangzhou China Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China MOE Key Lab of Disaster Forecast and Control in Engineering Guangzhou China

In this paper, a two-dimensional model of plasma diffusion in remote plasma source discharge chamber is established by COMSOL plasma module. The electron density and electron temperature distributions inside the discharge cavity were obtained by adjusting the thickness of alumina coating and the magnitude of RF power parameters. Based on the results, the authors discuss the effects of different alumina coating thickness and RF power on the electron density and electron temperature inside the discharge cavity, which provide theoretical guidance for the subsequent optimization of the internal structure of the discharge cavity and the discharge parameters.

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