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A dynamic stiffness-based framework for harmonic input estimation and response reconstruction considering damage

Frontiers of Structural and Civil Engineering 2022年第4期16卷 448-460页

作者： Yixian LI limin SUN Wang ZHU wei ZHANG Department of Bridge Engineering College of Civil EngineeringTongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in Civil Engineering Department of Bridge EngineeringCollege of Civil EngineeringTongji UniversityShanghai 200092China Shanghai Qizhi Institute Shanghai 200092China Sichuan Highway Planning SurveyDesignand Research Institute Ltd.Chengdu 610000China Fujian Key Laboratory of Green Building Technology Fujian Academy of Building ResearchFuzhou 350028China

In structural health monitoring(SHM),the measurement is point-wise but structures are continuous.Thus,input estimation has become a hot research subject with which the full-field structural response can be calculated with a finite element model(FEM).This paper proposes a framework based on the dynamic stiffness theory,to estimate harmonic input,reconstruct responses,and to localize damages from seriously deficient measurements.To begin,Fourier transform converts the dynamic equilibrium equation to an equivalent static one in the frequency domain,which is underdetermined since the dimension of measurement vector is far less than the FEM-node number.The principal component analysis has been adopted to“compress”the under-determined equation,and formed an over-determined equation to estimate the unknown input.Then,inverse Fourier transform converts the estimated input in the frequency domain to the time domain.Applying this to the FEM can reconstruct the target responses.If a structure is damaged,the estimated nodal force can localize the damage.To improve the damage-detection accuracy,a multi-measurement-based indicator has been proposed.Numerical simulations have validated that the proposed framework can capably estimate input and reconstruct multi-types of full-field responses,and the damage indicator can localize minor damages even with the existence of noise.

关键词： dynamic stiffness principal component analysis response reconstruction damage localization underdetermined equation

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深厚软土桥梁桩基荷载传递特性及沉降控制效果研究

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中国铁道科学 2012年第4期33卷 13-19页

作者： Xin, Xuezhong wei, limin He, Qun Hangzhou-Ningbo Passenger Dedicated Line Co. Ltd. Hangzhou Zhejiang 310009 China School of Civil Engineering Central South University Changsha Hunan 410075 China

通过杭甬铁路客运专线柯桥特大桥单桩静载试验,桩身应变、桩身压缩量及桥墩沉降的测试,研究深厚软土地区桥梁桩基的荷载传递特性及沉降控制效果。结果表明:桩侧摩阻力先于桩端阻力发挥作用;尽管桩端置于强风化凝灰质砂岩上,但在试验荷载... 详细信息

通过杭甬铁路客运专线柯桥特大桥单桩静载试验,桩身应变、桩身压缩量及桥墩沉降的测试,研究深厚软土地区桥梁桩基的荷载传递特性及沉降控制效果。结果表明:桩侧摩阻力先于桩端阻力发挥作用;尽管桩端置于强风化凝灰质砂岩上,但在试验荷载下2根超长试验桩的端承比均小于1.5%,桩的承载特性表现为摩擦桩的性质;单桩静载试验实测的桩身压缩量占桩顶沉降量的85%以上;桥墩浇筑完成后经过753d的沉降观测,2个试验墩实测沉降量分别为3.00和3.41mm,其中,无砟轨道铺设后300d的实测沉降分别为0.11和0.25mm,表明在深厚软土地区采用超长钻孔灌注桩控制桥梁基础沉降的效果显著。

关键词：桥梁桩基深厚软土超长钻孔灌注桩单桩静载试验荷载传递特性桩身变形沉降控制

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Theory and practice of unconventional gas exploration in carrier beds: Insight from the breakthrough of new type of shale gas and tight gas in Sichuan Basin, SW China

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Petroleum Exploration and Development 2023年第1期50卷 27-42页

作者： GUO Tonglou XIONG Liang YE Sujuan DONG Xiaoxia WEI Limin YANG Yingtao Sinopec Southwest Oil&Gas Company Chengdu 610041China

Unconventional gas in the Sichuan Basin mainly includes shale gas and tight gas.The development of shale gas is mainly concentrated in the Ordovician Wufeng Formation-Silurian Longmaxi Formation,but has not made any significant breakthrough in the Cambrian Qiongzhusi Formation marine shale regardless of exploration efforts for years.The commercial development of tight sandstone gas is mainly concentrated in the Jurassic Shaximiao Formation,but has not been realized in the widespread and thick Triassic Xujiahe Formation.Depending on the geological characteristics of the Qiongzhusi Formation and Xujiahe Formation,the feedback of old wells was analyzed.Then,combining with the accumulation mechanisms of con-ventional gas and shale gas,as well as the oil/gas shows during drilling,changes in production and pressure during develop-ment,and other characteristics,it was proposed to change the exploration and development strategy from source and reservoir exploration to carrier beds exploration.With the combination of effective source rock,effective carrier beds and effective sand-stone or shale as the exploration target,a model of unconventional gas accumulation and enrichment in carrier beds was built.Under the guidance of this study,two significant results have been achieved in practice.First,great breakthrough was made in exploration of the silty shale with low organic matter abundance in the Qiongzhusi Formation,which breaks the traditional approach to prospect shale gas only in organic-rich black shales and realizes a breakthrough in new areas,new layers and new types of shale gas and a transformation of exploration and development of shale gas from single-layer system,Longmaxi For-mation,to multi-layer system in the Sichuan Basin.Second,exploration breakthrough and high-efficient development were re-alized for difficult-to-produce tight sandstone gas reserves in the Xujiahe Formation,which helps address the challenges of low production and unstable production of fracture zones in the Xujiahe Formation,promote the tr

关键词： Sichuan Basin carrier bed tight gas shale gas silty shale Cambrian Qiongzhusi Formation Triassic Xujiahe Formation

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Time-dependent deviation of bridge pile foundations caused by adjacent large-area surcharge loads in soft soils and its preventive measures

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FRONTIERS OF STRUCTURAL AND CIVIL ENGINEERING 2024年第2期18卷 184-201页

作者： Li, Shuanglong wei, limin Niu, Jingtai Deng, Zhiping Wu, Bangbin Qian, Wuwen He, Feifei Nanchang Inst Technol Sch Hydraul Engn Nanchang 330099 Peoples R China Cent South Univ Sch Civil Engn Changsha 410075 Peoples R China

Time-dependent characteristics (TDCs) have been neglected in most previous studies investigating the deviation mechanisms of bridge pile foundations and evaluating the effectiveness of preventive measures. In this study, the stress-strain-time characteristics of soft soils were illustrated by consolidation-creep tests based on a typical engineering case. An extended Koppejan model was developed and then embedded in a finite element (FE) model via a user-material subroutine (UMAT). Based on the validated FE model, the time-dependent deformation mechanism of the pile foundation was revealed, and the preventive effect of applying micropiles and stress-release holes to control the deviation was investigated. The results show that the calculated maximum lateral displacement of the cap differs from the measured one by 6.5%, indicating that the derived extended Koppejan model reproduced the deviation process of the bridge cap-pile foundation with time. The additional load acting on the pile side caused by soil lateral deformation was mainly concentrated within the soft soil layer and increased with the increase in load duration. Compared with t = 3 d (where t is surcharge time), the maximum lateral additional pressure acting on Pile 2# increased by approximately 47.0% at t = 224 d. For bridge pile foundation deviation in deep soft soils, stress-release holes can provide better prevention compared to micropiles and are therefore recommended.

关键词： bridge pile foundation surcharge load soft soil time-dependent deformation interaction mechanism preventive measure BEHAVIOR ABUTMENTS DESIGN CLAY

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Ferric ion-triggered surface oxidation of galena for efficient chalcopyrite-galena separation

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 261-267页

作者： Qiancheng Zhang limin Zhang Feng Jiang Honghu Tang Li Wang wei Sun School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Engineering Research Center of Ministry of Education for Carbon Emission Reduction in Metal Resource Exploitation and Utilization Changsha 410083China School of Resource and Environment Hunan University of Technology and BusinessChangsha 410083China

The efficient separation of chalcopyrite(CuFeS2)and galena(PbS)is essential for optimal resource utilization.However,find-ing a selective depressant that is environmentally friendly and cost effective remains a challenge.Through various techniques,such as mi-croflotation tests,Fourier transform infrared spectroscopy,scanning electron microscopy(SEM)observation,X-ray photoelectron spec-troscopy(XPS),and Raman spectroscopy measurements,this study explored the use of ferric ions(Fe^(3+))as a selective depressant for ga-lena.The results of flotation tests revealed the impressive selective inhibition capabilities of Fe^(3+)when used alone.Surface analysis showed that Fe^(3+)significantly reduced the adsorption of isopropyl ethyl thionocarbamate(IPETC)on the galena surface while having a minimal impact on chalcopyrite.Further analysis using SEM,XPS,and Raman spectra revealed that Fe^(3+)can oxidize lead sulfide to form compact lead sulfate nanoparticles on the galena surface,effectively depressing IPETC adsorption and increasing surface hydrophilicity.These findings provide a promising solution for the efficient and environmentally responsible separation of chalcopyrite and galena.

关键词： galena chalcopyrite ferric ions flotation separation surface oxidation

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Certificateless designated verifier proxy signature scheme for unmanned aerial vehicle networks

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Science China(Information Sciences) 2021年第1期64卷 79-93页

作者： Lei HE Jianfeng MA limin SHEN Dawei wei School of Computer Science and Technology Xidian University School of Computer and Communication Engineering Zhengzhou University of Light Industry School of Cyber Engineering Xidian University School of Computer Science and Technology Nanjing Normal University

Unmanned aerial vehicle(UAV) technologies have a promising application prospect. It is necessary to use digital signature schemes to protect the integrity and authentication of messages in the UAV networks. According to the characteristics of UAV networks, digital signature schemes should solve the problems of digital certificate management and key escrow, guarantee the real-time performance of UAV executing commands, and ensure that only the designated verifier can verify the signature. Therefore, we proposed a certificateless designated verifier proxy signature(CLDVPS) scheme which meets the requirements. We proved our signature scheme is existentially unforgeable under an adaptive chosen message attack in the random oracle model and compared the efficiency of our signature scheme with other signature schemes.We implemented these signature schemes in jPBC to obtain the computing time and theoretically analyzed signature length of these signature schemes. The analysis results indicate that our CLDVPS scheme is more efficient than most of other related signature schemes on computation costs and also efficient on communication costs.

关键词： certificateless designated verifier proxy digital signature unmanned aerial vehicle

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Characterization of the Flexural Behavior of Bamboo Beams

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Journal of Renewable Materials 2021年第9期9卷 1571-1597页

作者： limin Tian Jianpeng wei Jiping Hao Qiushuo Wang School of Civil Engineering Shaanxi Key Laboratory of Structure and Earthquake ResistanceXi’an University of Architecture and TechnologyXi’an710055China The Key Laboratory of Plateau Building and Eco-Community in Qinghai Qinghai Building and Materials Research Co.Ltd.Xining810008China Anhui Province Key Laboratory of Green Building and Assembly Construction Anhui Institute of Building Research&DesignHefei230031China

Bamboo is a renewable and environmentally friendly material often used for construction.This study investigates the flexural behavior of bamboo beams through theoretical and finite element(FE)analyses.Considering the material’s nonlinearity,a method of calculating load-deflection curves is proposed and validated via FE analysis.The interfacial slippage dominated by the shear stiffness of the interface between two bamboo poles significantly influences the flexural behavior of double-pole bamboo beams.Thus,the load-deflection curves for different shear stiffnesses can be obtained via theoretical and FE analyses.Subsequently,a novel configuration using diagonal steel bands to avoid slippage is presented.An inclination angle of 45°is suggested to adequately develop the stiffness and bearing capacity of the steel band.

关键词： Bamboo beam flexural behavior interfacial slippage steel band FE analysis

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Three-dimensional structural Cu^(6)Sn_(5)/carbon nanotubes alloy thin-film electrodes fabricated by in situ electrodeposition from the leaching solution of waste-printed circuit boards

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International Journal of Minerals,Metallurgy and Materials 2023年第6期30卷 1171-1180页

作者： Shuqing Nie Yu Xin Qiuyun Wang Chengjin Liu Chang Miao limin Yu wei Xiao College of Chemistry and Environmental Engineering Yangtze UniversityJingzhou 434023China

Tin-based materials are very attractive anodes because of their high theoretical capacity,but their rapid capacity fading from volume expansions limits their practical applications during alloying and dealloying processes.Herein,the improved binder-free tin-copper intermetallic/carbon nanotubes(Cu6Sn5/CNTs)alloy thin-film electrodes are directly fabricated through efficient in situ electrodeposition from the leaching solution of treated waste-printed circuit boards(WPCBs).The characterization results show that the easily agglomerated Cu6Sn5 alloy nanoparticles are uniformly dispersed across the three-dimensional network when the CNTs concentration in the electrodeposition solution is maintained at 0.2 g·L−1.Moreover,the optimal Cu6Sn5/CNTs-0.2 alloy thin-film electrode can not only provide a decent discharge specific capacity of 458.35 mAh·g^(−1)after 50 cycles at 100 mA·g^(−1)within capacity retention of 82.58%but also deliver a relatively high reversible specific capacity of 518.24,445.52,418.18,345.33,and 278.05 mAh·g^(−1)at step-increased current density of 0.1,0.2,0.5,1.0,and 2.0 A·g^(−1),respectively.Therefore,the preparation process of the Cu6Sn5/CNTs-0.2 alloy thin-film electrode with improved electrochemical performance may provide a cost-effective strategy for the resource utilization of WPCBs to fabricate anode materials for lithium-ion batteries.

关键词： tin-copper intermetallic in situ electrodeposition carbon nanotubes anode material lithium-ion battery

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Queue-aware energy-efficient scheduling and power allocation with feedback reduction in small-cell networks

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Science China(Information Sciences) 2018年第4期61卷 246-252页

作者： Hongxin wei Yunzhou LI limin XIAO Shidong ZHOU State Key Laboratory on Microwave and Digital Communications Tsinghua National Laboratory Information Science and Technology Department of Electronic Engineering Tsinghua University

In small cell networks(SCNs),the path loss becomes smaller,and energy efficiency could be improved.If plenty of small base stations(BSs)are deployed,the energy consumption of each BSs can be small enough to make the t... 详细信息

关键词： CSI Queue-aware energy-efficient scheduling and power allocation with feedback reduction in small-cell networks

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A study on periodic boundary condition in direct numerical simulation for gas–solid flow

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Chinese Journal of Chemical Engineering 2020年第1期28卷 236-241页

作者： Shiwen Liu Xiaowen Liu Feiguo Chen limin Wang wei Ge State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China

Direct numerical simulation(DNS) of gas–solid flow at high resolution has been carried out by coupling the lattice Boltzmann method(LBM) for gas flow and the discrete element method(DEM) for solid particles. However,the body force periodic boundary condition(FPBC) commonly used to cut down the huge computational cost of such simulation has faced accuracy concerns. In this study, a novel two-region periodic boundary condition(TPBC) is presented to remedy this problem, with the flow driven in the region with body force and freely evolving in the other region. With simulation cases for simple circulating fluidized bed risers, the validity and advantages of TPBC are demonstrated with more reasonable heterogeneity of the particle distribution as compared to the corresponding case with FPBC.

关键词： Direct numerical simulation Periodic boundary condition Two-region periodic boundary condition Gas–solid flow Heterogeneity

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