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Dynamic Characteristics of Functionally Graded Timoshenko Beams by Improved Differential Quadrature Method

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Computer Modeling in eng.neering & Sciences 2024年第8期140卷 1647-1668页

作者： Xiaojun Huang Liaojun Zhang Hanbo Cui Gaoxing Hu School of Architecture and civil eng.neering Anhui Polytechnic UniversityWuhu241000China college of water conservancy and Hydropower eng.neering Hohai UniversityNanjing210098China

This study proposes an effective method to enhance the accuracy of the Differential Quadrature Method(DQM)for calculating the dynamic characteristics of functionally graded beams by improving the form of discrete node ***,based on the first-order shear deformation theory,the governing equation of free vibration of a functionally graded beam is transformed into the eigenvalue problem of ordinary differential equations with respect to beam axial displacement,transverse displacement,and cross-sectional rotation angle by considering the effects of shear deformation and rotational inertia of the beam ***,ignoring the shear deformation of the beam section and only considering the effect of the rotational inertia of the section,the governing equation of the beam is transformed into the eigenvalue problem of ordinary differential equations with respect to beam transverse *** on the differential quadrature method theory,the eigenvalue problem of ordinary differential equations is transformed into the eigenvalue problem of standard generalized algebraic ***,the first several natural frequencies of the beam can be *** feasibility and accuracy of the improved DQM are verified using the finite element method(FEM)and combined with the results of relevant literature.

关键词： Timoshenko beams functionally graded materials dynamic characteristics natural frequency improved differential quadrature method

An efficient approach for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic excitations

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Earthquake eng.neering and eng.neering Vibration 2024年第3期23卷 677-690页

作者： Huang Huan Li Yingxiong Li Yuyu college of water conservancy and civil eng.neering South China Agricultural UniversityGuangzhou 510642China Institute of Smart City and Intelligent Transportation Southwest Jiaotong UniversityChengdu 611756China

An efficient approach is proposed for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic *** concentrated plastic hinges,described by the Bouc-Wen model,are assumed to occur at the two ends of a linear-elastic beam *** auxiliary differential equations governing the plastic rotational displacements and their corresponding hysteretic displacements are replaced with linearized differential ***,the two sets of equations of motion for the original nonlinear system can be reduced to an expanded-order equivalent linearized equation of motion for equivalent linear *** solve the equation of motion for equivalent linear systems,the nonstationary random vibration analysis is carried out based on the explicit time-domain method with high ***,the proposed treatment method for initial values of equivalent parameters is investigated in conjunction with parallel computing technology,which provides a new way of obtaining the equivalent linear systems at different time *** on the explicit time-domain method,the key responses of interest of the converged equivalent linear system can be calculated through dimension reduction analysis with high *** examples indicate that the proposed approach has high computational efficiency,and shows good applicability to weak nonlinear and medium-intensity nonlinear systems.

关键词： nonstationary random vibration plastic hinge equivalent linearization method explicit time-domain method parallel computation

Stability behavior of the Lanxi ancient flood control levee after reinforcement with upside-down hanging wells and grouting curtain

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Journal of Mountain Science 2024年第1期21卷 84-99页

作者： QIN Zipeng.TIAN Yan GAO Siyuan ZHOU Jianfen HE Xiaohui HE Weizhong GAO Jingquan School of water conservancy and Environment eng.neering Zhejiang University of Water Resources and Electric PowerHangzhou 310018China Department of civil eng.neering Imperial College LondonLondonSW71BFEngland Lanxi water Affairs Bureau Lanxi 321102China Zhejiang water conservancy eng.neering Consulting Co. LtdHangzhou 310051China

The stability of the ancient flood control levees is mainly influenced by water level fluctuations, groundwater concentration and rainfalls. This paper takes the Lanxi ancient levee as a research object to study the evolution laws of its seepage, displacement and stability before and after reinforcement with the upside-down hanging wells and grouting curtain through numerical simulation methods combined with experiments and observations. The study results indicate that the filled soil is less affected by water level fluctuations and groundwater concentration after reinforcement. A high groundwater level is detrimental to the levee's long-term stability, and the drainage issues need to be fully considered. The deformation of the reinforced levee is effectively controlled since the fill deformation is mainly borne by the upside-down hanging wells. The safety factors of the levee before reinforcement vary significantly with the water level. The minimum value of the safety factors is 0.886 during the water level decreasing period, indicating a very high risk of the instability. While it reached 1.478 after reinforcement, the stability of the ancient levee is improved by a large margin.

关键词： Stability analysis Multiple factors Antiseepage reinforcement Upside-down hanging well Grouting curtain Ancient levee

An analytical transient coal permeability model:Sorption non-equilibrium index-based swelling switch

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Journal of Rock Mechanics and Geotechnical eng.neering 2024年第4期16卷 1175-1191页

作者： Xingxing Liu Jishan Liu Liang Chen Jinchang Sheng.Huimin Wang college of civil and Transportation eng.neering Hohai UniversityNanjing210098China School of eng.neering The University of Western Australia35 Stirling HighwayCrawleyWA6009Australia college of water conservancy and Hydropower eng.neering Hohai UniversityNanjing210098China

Long-term permeability experiments have indicated that sorption-induced swelling can switch from internal to bulk depending on the evolutive sorption ***,this sorption swelling switch mechanism has not been considered in current analytical permeability *** study introduces a normalized sorption non-equilibrium index(SNEI)to characterize the sorption status,quantify the dynamical variations of matrix swelling accumulation and internal swelling partition,and formulate the sorption swelling switch *** incorporation of this index into the extended total effective stress concept leads to an analytical transient coal permeability *** results show that the sorption swelling switch itself results in the permeability switch under stress-constrained conditions,while the confined bulk swelling suppresses the permeability recovery to the continuous reduction under displacement-constrained *** verifications show that current experimental observations correspond to the early stages of the transient process,and they could be extended to the whole process with these *** study demonstrates the importance of the sorption swelling switch in determining permeability evolution using simple boundary *** provides new insights into experimentally revealing the sorption swelling switch in the future,and underscores the requirement of a rigorous model for complex coupled processes in large-scale coal seams.

关键词： Coal permeability Sorption swelling switch Sorption non-equilibrium Boundary conditions

Urban Flood Mitigation Strategies with Coupled Gray–Green Measures: A Case Study in Guangzhou City, China

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International Journal of Disaster Risk Science 2024年第3期15卷 467-479页

作者： Jiayue Li Jiajun Zeng.Guoru Huang Wenjie Chen School of civil eng.neering and Transportation South China University of Technology School of Architecture South China University of Technology State Key Laboratory of Subtropical Building and Urban Science South China University of Technology college of water conservancy and civil eng.neering South China Agricultural University

The integration of gray and green infrastructure has proven to be a feasible approach for managing stormwater in established urban areas. However, evaluating the specific contributions of such coupled strategies is challeng.ng. This study introduced a novel integrated hydrological-hydrodynamic model that takes into account the layout of low-impact development(LID)facilities along with pipeline alignment and rehabilitation. Reliable results from modeling were used to assess the individual contribution of LID and improved drainage facilities to urban flooding mitigation. We selected a natural island in Guangzhou City, China, as the study site. The results indicate that combining three LID measures, namely green roofs, sunken green spaces, and permeable pavements, can reduce total runoff by 41.7% to 25.89% for rainfall recurrence periods ranging from 1year to 100 years, and decrease the volume of nodal overflow by nearly half during rainfall events of less than 10-year return period. By integrating LID measures with the upgraded gray infrastructure, the regional pipeline overloading condition is substantially alleviated, resulting in a significant improvement in pipeline system resilience. For urban flooding control, it is recommended to integrate sufficient green space and avoid pipe-laying structural issues during urban planning and construction. The findings may assist stakeholders in developing strategies to best utilize gray and green infrastructure in mitigating the negative eff ects of urban flooding.

关键词： Coupled hydrodynamic model Gray–green approach Guangzhou City LID Pipe renovation Urban inundation

Advancement of metal(loid)research on farmland

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Frontiers of Agricultural Science and eng.neering 2024年第3期11卷 442-467页

作者： Qiang ZHeng.Chenchen WEI Yanbing CHI Peiling YANG college of water Resources and civil eng.neering China Agricultural UniversityBeijing 100083China Agricultural water conservancy Department Changjiang River Scientific Research InstituteWuhan 430019China Zhejiang University of water Resources and Electric Power Hangzhou 310018China

Metal(loid)pollution has emerged as a pressing environmental issue in agriculture,garnering extensive public ***(loid)s are potentially toxic substances that infiltrate the soil through diverse pathways,leading to food chain contamination via plant uptake and subsequent animal *** poses a serious threat to environmental quality,food security,and human ***,the remediation of metal(loid)-contaminated agricultural soil is an urgent concern demanding immediate ***,the majority of research papers concentrate on established,isolated remediation technologies,often overlooking comprehensive field management *** is imperative to provide a comprehensive summary of remediation technologies and identify future development *** review aims to comprehensively summarize a range of soil remediation and enhancement technologies,incorporating insights from multiple disciplines including physics,chemistry,biology,and their interdisciplinary *** review examines the mechanisms of action,suitable scenarios,advantages,disadvantages,and benefits associated with each remediation *** relevant is the examination of metal(loid)sources,as well as the mechanisms behind both established and innovative,efficient remediation and enhancement ***,the future evolution of remediation technologies are considered with the aim of offering a scientific research foundation and inspiration to fellow *** is intended to facilitate the advancement of remediation technologies and establish a robust foundation for sustainable development of soil.

关键词： Metal(loid)pollution metal(loid)remediation metal(loid)sources soil

What control the spatial patterns and predictions of runoff response over the contiguous USA?

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Journal of Geographical Sciences 2024年第7期34卷 1297-1322页

作者： JIANG Shanhu DU Shuping REN Liliang GONG Xinglong YAN Deng.ua YUAN Shanshui LIU Yi YANG Xiaoli XU Chongyu The National Key Laboratory of water Disaster Prevention Hohai UniversityNanjing210098China college of Hydrology and water Resources Hohai UniversityNanjing210098China School of water conservancy&civil eng.neering Northeast Agricultural UniversityHarbin150030China Department of water Resources China Institute of Water Resources and Hydropower ResearchBeijing100038China Department of Geosciences University of OsloOsloNorway

Understanding the nonlinear relationship between hydrological response and key factors and the cause behind this relationship is vital for water resource management and earth system *** this study,we undertook several steps to explore the ***,we partitioned runoff response change(RRC)into multiple components associated with climate and catchment properties,and examined the spatial patterns and smoothness indicated by the Moran's Index of RRC across the contiguous United States(CONUS).Subsequently,we employed a machine learning model to predict RRC using catchment attribute predictors encompassing climate,topography,hydrology,soil,land use/cover,and ***,we identified the primary factors influencing RRC and quantified how these key factors control RRC by employing the accumulated local effect,which allows for the representation of not only dominant but also secondary ***,we explored the relationship between ecoregion patterns,climate gradients,and the distribution of RRC across *** findings indicate that:(1)RRC demonstrating significant connections between catchments tends to be well predicted by catchment attributes in space;(2)climate,hydrology,and topography emerge as the top three key attributes nonlinearly influencing the RRC patterns,with their second-order effects determining the heterogeneous patterns of RRC;and(3)local Moran's I signifies a collaborative relationship between the patterns of RRC and their spatial smoothness,climate space,and ecoregions.

关键词： hydrological response prediction machine learning accumulated local effect Moran’s Index large-sample study

Numerical simulation on the influence of plant root morphology on shear streng.h in the sandy soil, Northwest China

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Journal of Arid Land 2024年第10期16卷 1444-1462页

作者： ZHANG Lingkai SUN Jin SHI Chong college of water Resources and civil eng.neering Xinjiang Agricultural University Xinjiang Key Laboratory of water conservancy eng.neering Safety and water Disaster Prevention and Control Geotechnical Research Institute Hohai University

Serious riverbank erosion, caused by scouring and soil siltation on the bank slope in the lower reaches of the Tarim River, Northwest China urgently requires a solution. Plant roots play an important role in enhancing soil shear streng.h on the slopes to maintain slope soils, but the extent of enhancement of soil shear streng.h by different root distribution patterns is unclear. The study used a combination of indoor experiments and numerical simulation to investigate the effects of varying plant root morphologies on the shear streng.h of the sandy soil in the Tarim River. The results showed that:(1) by counting the root morphology of dominant vegetation on the bank slope, we summarized the root morphology of dominant vegetation along the coast as vertical, horizontal, and claw type;(2) the shear streng.h of root-soil composites(RSCs) was significantly higher than that of remolded soil, and the presence of root system made the strain-softening of soil body significantly weakened so that RSCs had better mechanical properties; and(3) compared with the lateral roots, the average particle contact degree of vertical root system was higher, and the transition zone of shear streng.h was more prominent. Hence, vegetation with vertical root system had the best effect on soil protection and slope fixation. The results of this study have important guiding significance for prevention and control of soil erosion in the Tarim River basin, the restoration of riparian ecosystems, and the planning of water conservancy projects.

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A Modified Principal Component Analysis Method for Honeycomb Sandwich Panel Debonding Recognition Based on Distributed Optical Fiber Sensing Signals

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Structural Durability & Health Monitoring 2024年第2期18卷 125-141页

作者： Shuai Chen Yinwei Ma Zhongshu Wang Zongmei Xu Song Zhang Jianle Li Hao Xu Zhanjun Wu State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian116024China Beijing Aerospace Technology Institution Beijing116024China college of water-conservancy and civil eng.neering Shandong Agricultural UniversityTaian271000China

The safety and integrity requirements of aerospace composite structures necessitate real-time health monitoring throughout their service *** this end,distributed optical fiber sensors utilizing back Rayleigh scattering have been extensively deployed in structural health monitoring due to their advantages,such as lightweight and ease of ***,identifying the precise location of damage from the optical fiber signals remains a critical *** this paper,a novel approach which namely Modified Sliding Window Principal Component Analysis(MSWPCA)was proposed to facilitate automatic damage identification and localization via distributed optical fiber *** proposed method is able to extract signal characteristics interfered by measurement noise to improve the accuracy of damage ***,we applied the MSWPCA method to monitor and analyze the debonding propagation process in honeycomb sandwich panel *** findings demonstrate that the training model exhibits high precision in detecting the location and size of honeycomb debonding,thereby facilitating reliable and efficient online assessment of the structural health state.

关键词： Structural health monitoring distributed opticalﬁber sensor damage identiﬁcation honeycomb sandwich panel principal component analysis