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Effects of grain's shape-and size-polydispersities,orientation,and area fraction on tortuosity and permeability of 2D granular media

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Particuology 2024年第7期90卷 535-557页

作者： Ke Cao Huisu Chen Mohammad Iqbal Khan Mingqi Li Lin Liu Jiangsu Key Laboratory of Construction Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China department of civil engineering College of EngineeringKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia School of civil and Transportation engineering Hebei University of TechnologyTianjin 300401China College of civil and Transportation engineering Hohai UniversityNanjing210098China

The microstructure of granular media, including grain's shape- and size-polydispersities, orientation, and area fraction can potentially affect its permeability. However, few studies consider the coupling effects of these features. This work employs geometrical probability and stereology to establish quantitative relationships between the above microstructural features and the geometric tortuosity of the two-dimensional granular media containing superellipse, superoval, and polygon grains. Then the lattice Boltzmann method (LBM) is used to determine the permeabilities of these granular media. By combining the tortuosity model and the LBM-derived permeabilities, modified K–C equations are formulated to predict the permeability and the shape factor, considering the grain's shape- and size-polydispersities, orientation, and area fraction. The reliability of these methods can be verified by comparing them with both our simulations and available experimental, theoretical, and numerical data reported in the literature. The findings implicate that the tortuosity and permeability of the granular media are strongly correlated with the grain's shape, orientation, and area fraction but unaffected by the size polydispersity and spatial arrangement of grains. Only circularity is not enough to derive a unified formula for considering the impact of grain shape on tortuosity and permeability, other shape parameters need to be explored in the future.

关键词： Geometric tortuosity Konzey-Carman equation Shape and size ploydispersities Grain orientation Lattice Boltzmann method Granular media

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Laboratory study of a hydronic concrete deck heated externally in a controlled sub-freezing environment

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Energy and Built Environment 2024年第1期5卷 9-23页

作者： Mark Hurley Omid Habibzadeh-Bigdarvish Gang Lei Xinbao Yu department of civil engineering University of Texas at ArlingtonTX 76019United States

Geothermal heating of bridge decks is a reliable and sustainable method for bridge de-icing that has been in-creasing in demand since conventional de-icing methods were proved to be environmentally *** research on geothermal heating of bridge decks relied on hydronic pipes embedded inside of bridge decks,which are confined to newly constructed *** existing bridges,a newly devised method for external heating has been recently tested under limited laboratory conditions to determine its overall *** study explores laboratory heating tests of a concrete slab with a thickness representing a typical concrete bridge *** slab was equipped with a simulated geothermal bridge de-icing system and tested inside a freezer subjected to sub-freezing controlled *** winter scenarios were applied to the system to determine its heat-ing performance and how feasible it will be for the system to be transferred to the field.A prediction equation was developed to estimate the total energy reserves required to permit de-icing,and statistical analysis was performed and validated with test *** slab surface heat flux was estimated to range from 27 W/m^(2) K to 73 W/m^(2) K from the heating *** externally-heated deck can be designed with the developed prediction equation for snow melting.

关键词： Thermal demands Bridge deck de-icing Attached hydronic loops Heated bridge deck Heat flux analysis

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AHermitian C^(2) Differential Reproducing Kernel Interpolation Meshless Method for the 3D Microstructure-Dependent Static Flexural Analysis of Simply Supported and Functionally Graded Microplates

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Computer Modeling in engineering & Sciences 2024年第10期141卷 917-949页

作者： Chih-Ping Wu Ruei-Syuan Chang department of civil engineering National Cheng Kung UniversityTainan70101Taiwan

This work develops a Hermitian C^(2) differential reproducing kernel interpolation meshless(DRKIM)method within the consistent couple stress theory(CCST)framework to study the three-dimensional(3D)microstructuredependent static flexural behavior of a functionally graded(FG)microplate subjected to mechanical loads and placed under full simple *** the formulation,we select the transverse stress and displacement components and their first-and second-order derivatives as primary ***,we set up the differential reproducing conditions(DRCs)to obtain the shape functions of the Hermitian C^(2) differential reproducing kernel(DRK)interpolant’s derivatives without using direct *** interpolant’s shape function is combined with a primitive function that possesses Kronecker delta properties and an enrichment function that constituents *** a result,the primary variables and their first-and second-order derivatives satisfy the nodal interpolation ***,incorporating ourHermitianC^(2)DRKinterpolant intothe strong formof the3DCCST,we develop a DRKIM method to analyze the FG microplate’s 3D microstructure-dependent static flexural *** Hermitian C^(2) DRKIM method is confirmed to be accurate and fast in its convergence rate by comparing the solutions it produces with the relevant 3D solutions available in the ***,the impact of essential factors on the transverse stresses,in-plane stresses,displacements,and couple stresses that are induced in the loaded microplate is *** factors include the length-to-thickness ratio,the material length-scale parameter,and the inhomogeneity index,which appear to be significant.

关键词： Consistent/modified couple stress theory differential reproducing kernel methods microplates point collocation methods static flexural 3D microstructure-dependent analysis

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Multi-population particle swarm optimization algorithm for automatic design of steel frames

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Frontiers of Structural and civil engineering 2024年第1期18卷 89-103页

作者： Wenchen SHAN Jiepeng LIU Yao DING Y.Frank CHEN Junwen ZHOU Institute of Smart City and Intelligent Transportation Southwest Jiaotong UniversityChengdu 610000China School of civil engineering Chongqing UniversityChongqing 400045China department of civil engineering the Pennsylvania State UniversityMiddletownPA 17057USA

Steel structures are widely used;however,their traditional design method is a trial-and-error procedure which is neither efficient nor cost ***,a multi-population particle swarm optimization(MPPSO)algorithm is developed to optimize the weight of steel frames according to standard design *** are made to improve the algorithm performances including the constraint-based strategy,piecewise mean learning strategy and multi-population cooperative *** proposed method is tested against the representative frame taken from American standards and against other steel frames matching Chinese design *** related parameter influences on optimization results are *** the representative frame,MPPSO can achieve greater efficiency through reduction of the number of analyses by more than 65% and can obtain frame with the weight for at least 2.4%lighter.A similar trend can also be observed in cases subjected to Chinese design *** addition,a migration interval of 1 and the number of populations as 5 are recommended to obtain better MPPSO *** purpose of the study is to propose a method with high efficiency and robustness that is not confined to structural scales and design *** aims to provide a reference for automatic structural optimization design problems even with dimensional *** proposed method can be easily generalized to the optimization problem of other structural systems.

关键词： steel frame multi-population particle swarm optimization automatic structural optimization design

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A novel low-cost visual ear tag based identification system for precision beef cattle livestock farming

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Information Processing in Agriculture 2024年第1期11卷 117-126页

作者： Andrea Pretto Gianpaolo Savio Flaviana Gottardo Francesca Uccheddu Gianmaria Concheri department of civil Environmental and Architectural EngineeringUniversity of PaduaItaly department of Animal Medicine Production and HealthUniversity of PadovaItaly department of Industrial engineering University of PadovaItaly

The precision livestock farming(PLF)has the objective to maximize each animal's performance while reducing the environmental impact and maintaining the quality and safety of meat *** the PLF techniques,the personalised management of each individual animal based on sensors systems,represents a viable *** is worth noting that the implementation of an effective PLF approach can be still expensive,especially for small and medium-sized farms;for this reason,to guarantee the sustainability of a customized livestock management system and encourage its use,plug and play and cost-effective systems are *** this context,we present a novel low-cost method for identifying beef cattle and recognizing their basic activities by a single surveillance *** leveraging the current state-of-the-art methods for real-time object detection,(i.e.,YOLOv3)cattle's face areas,we propose a novel mechanism able to detect the ear tag as well as the water ingestion state when the cattle is close to the *** cow IDs are read by an Optical Character Recognition(OCR)algorithm for which,an ad hoc error correction algorithm is here presented to avoid numbers misreading and correctly match the IDs to only actually present *** to the detection of the tag position,the OCR algorithm can be applied only to a specific region of interest reducing the computational cost and the time *** times for the areas are outputted as cattle activity recognition *** results demonstrate the effectiveness of our proposed method,showing a mAP@0.50 of 89%.

关键词： Precision livestock farming Deep learning Cattlei dentification Low-cost sensors Computer vision

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Construction Activity Analysis of Workers Based on Human Posture Estimation Information

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engineering 2024年第2期33卷 225-236页

作者： Xuhong Zhou Shuai Li Jiepeng Liu Zhou Wu Yohchia Frank Chen School of civil engineering Chongqing UniversityChongqing 400044China School of Automation Chongqing UniversityChongqing 400044China department of civil engineering The Pennsylvania State UniversityMiddletownPA 17057USA

Identifying workers’construction activities or behaviors can enable managers to better monitor labor efficiency and construction ***,current activity analysis methods for construction workers rely solely on manual observations and recordings,which consumes considerable time and has high labor *** have focused on monitoring on-site construction activities of ***,when multiple workers are working together,current research cannot accu rately and automatically identify the construction *** research proposes a deep learning framework for the automated analysis of the construction activities of multiple *** this framework,multiple deep neural network models are designed and used to complete worker key point extraction,worker tracking,and worker construction activity *** designed framework was tested at an actual construction site,and activity recognition for multiple workers was performed,indicating the feasibility of the framework for the automated monitoring of work efficiency.

关键词： Pose estimation Activity analysis Object tracking Construction workers Automatic systems

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UV-Based Advanced Oxidation Processes for Antibiotic Resistance Control: Efficiency, Influencing Factors, and Energy Consumption

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engineering 2024年第6期37卷 27-39页

作者： Jiarui Han Wanxin Li Yun Yang Xuanwei Zhang Siyu Bao Xiangru Zhang Tong Zhang Kenneth Mei Yee Leung department of civil and Environment engineering The Hong Kong University of Science and TechnologyHong Kong 999077China department of civil engineering The University of Hong KongHong Kong 999077China State Key Laboratory of Marine Pollution and department of Chemistry City University of Hong KongHong Kong 999077China

Antibiotic resistant bacteria(ARB)with antibiotic resistance genes(ARGs)can reduce or eliminate the effectiveness of antibiotics and thus threaten human *** United Nations Environment Programme considers antibiotic resistance the first of six emerging issues of *** oxidation processes(AOPs)that combine ultraviolet(UV)irradiation and chemical oxidation(primarily chlorine,hydrogen peroxide,and persulfate)have attracted increasing interest as advanced water and wastewater treatment *** integrated technologies have been reported to significantly elevate the efficiencies of ARB inactivation and ARG degradation compared with direct UV irradiation or chemical oxidation alone due to the generation of multiple reactive *** this study,the performance and underlying mechanisms of UV/chlorine,UV/hydrogen peroxide,and UV/persulfate processes for controlling ARB and ARGs were reviewed based on recent *** affecting the process-specific efficiency in controlling ARB and ARGs were discussed,including biotic factors,oxidant dose,UV fluence,pH,and water matrix *** addition,the cost-effectiveness of the UV-based AOPs was evaluated using the concept of electrical energy per *** UV/chlorine process exhibited a higher efficiency with lower energy consumption than other UV-based AOPs in the wastewater matrix,indicating its potential for ARB inactivation and ARG degradation in wastewater *** studies are required to address the trade-off between toxic byproduct formation and the energy efficiency of the UV/chlorine process in real wastewater to facilitate its optimization and application in the control of ARB and ARGs.

关键词： Advanced oxidation processes Ultraviolet/chlorine Ultraviolet/hydrogen peroxide Ultraviolet/persulfate Antibiotic resistant bacteria Antibiotic resistance genes

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Seismic responses of an intensively constructed metro station-passageway-shaft structure system

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Frontiers of Structural and civil engineering 2024年第5期18卷 760-775页

作者： Ruohan LI Yong YUAN Hong CHEN Xinxing LI Emilio BILOTTA department of Geotechnical engineering Tongji UniversityShanghai 200092China department of civil Architectural and Environmental EngineeringUniversity of Naples Federico IINaples 80125Italy State Key Laboratory of Disaster Reduction in civil engineering Tongji UniversityShanghai 200092China Shanghai Tunnel engineering&Rail Transit Design and Research Institute Shanghai 200235China

Intensive construction methods offer benefits for metro station development,yet they present challenges for seismic design due to the spatially asymmetric configuration of passageway-shaft *** this study,a detailed numerical model of a station-passageway-shaft structure system built using intensive construction methods was developed and the deformation and damage modes under seismic loadings were *** results indicate that inconsistent deformation between the shaft and the station generates interaction through the connecting passageway,leading to damage near the opening of the station structure and both ends of the connecting passageway Damage is more severe under longitudinal *** with the opening plan that spans four segments,the opening plan that spans five segments exacerbates the overall degree of damage to the structure *** transverse excitation,the presence of interior structures intensifies the damage to the station and connecting passageway,while with such internal structure in place the impact is relatively minor under longitudinal *** with steel segments near the station opening can appreciably attenuate the *** contrast,introducing flexible joints at both ends of the connecting passageway intensifies the ***,reinforcement using steel segments emerges as an optimal seismic mitigation strategy.

关键词： earthquake intensive construction metro station numerical simulation

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Transfer learning framework for multi-scale crack type classification with sparse microseismic networks

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International Journal of Mining Science and Technology 2024年第2期34卷 167-178页

作者： Arnold Yuxuan Xie Bing QLi department of civil and Environmental engineering Western UniversityLondon N6A 3K7Canada

Rock fracture mechanisms can be inferred from moment tensors(MT)inverted from microseismic ***,MT can only be inverted for events whose waveforms are acquired across a network of *** is limiting for underground mines where the microseismic stations often lack azimuthal ***,there is a need for a method to invert fracture mechanisms using waveforms acquired by a sparse microseismic ***,we present a novel,multi-scale framework to classify whether a rock crack contracts or dilates based on a single *** framework consists of a deep learning model that is initially trained on 2400000+manually labelled field-scale seismic and microseismic waveforms acquired across 692 *** learning is then applied to fine-tune the model on 300000+MT-labelled labscale acoustic emission waveforms from 39 individual experiments instrumented with different sensor layouts,loading,and rock types in *** optimal model achieves over 86%F-score on unseen waveforms at both the lab-and *** model outperforms existing empirical methods in classification of rock fracture mechanisms monitored by a sparse microseismic *** facilitates rapid assessment of,and early warning against,various rock engineering hazard such as induced earthquakes and rock bursts.

关键词： Multi-scale Fracture processes Microseismic Acoustic emission Source mechanism Deep learning

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Development of component stiffness equations for thread-fixed one-side bolt connections to an enclosed rectangular hollow section column under tension

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Frontiers of Structural and civil engineering 2024年第4期18卷 568-586页

作者： Fu-Wei WU Yuan-Qi LI department of Structural engineering Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in civil engineering Tongji UniversityShanghai 200092China

The derivation and validation of analytical equations for predicting the tensile initial stiffness of threadfixed one-side bolts(TOBs),connected to enclosed rectangular hollow section(RHS)columns,is presented in this *** unknown stiffness components are considered:the TOBs connection and the enclosed RHS ***,the trapezoidal thread of TOB,as an equivalent cantilevered beam subjected to uniformly distributed loads,is analyzed to determine the associated *** on the findings,the thread-shank serial-parallel stiffness model of TOB connection is *** analysis of the tensile stiffness of the enclosed RHS face due to two bolt forces,the four sidewalls are treated as rotation constraints,thus reducing the problem to a two-dimensional plate *** to the load superposition method,the deflection of the face plate is resolved into three components under various boundary and load *** to the plate deflection theory of Timoshenko,the analytical solutions for the three deflections are derived in terms of the variables of bolt spacing,RHS thickness,height to width ratio,***,the validity of the above stiffness equations is verified by a series of finite element(FE)models of T-stub *** proposed component stiffness equations are an effective supplement to the component-based method.

关键词： initial stiffness component based method thread-fixed one-side bolt rectangular hollow sections analytical equation

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