The Portland cement concrete pavement(PCCP)often suffers from different environmental distresses and vehicle load failure,resulting in slab corner fractures,potholes,and other diseases.Rapid repair has become one of t...The Portland cement concrete pavement(PCCP)often suffers from different environmental distresses and vehicle load failure,resulting in slab corner fractures,potholes,and other diseases.Rapid repair has become one of the effective ways to open traffic rapidly.In this study,a novel type of rapid repair material,basalt fiber reinforced polymer modified magnesium phosphate cement(BFPMPC),is used to rapidly repair PCCP.Notably,the mechanical properties and characteristics of the repair interfaces which are named interfacial transition zones(ITZs)formed by BFPMPC and cement concrete are focused on as a decisive factor for the performance of the rapid repair.The changing trend of the elastic moduli was studied by nanoindentation experiments in the ITZs with the deconvolution analysis that the elastic moduli of certain kinds of substances can be determined.The experimental results show that the elastic modulus of ITZ-1 with a width of about20μm can be regarded as 0.098 times of the aggregate,and 0.51 times of the ordinary Portland cement(OPC)mortar.The BFPMPC-OPC mortar ITZ has roughly the same mechanical properties as the ITZ between aggregate and BFPMPC.A multi-scale representative two-dimensional model was established by random aggregate and a two-dimensional extended finite element method(XFEM)to study the mechanical properties of the repair interface.The simulation results show that the ITZ formed by the interface of BFPMPC and OPC mortar and basalt aggregate is the most vulnerable to failure,which is consistent with the nano-indentation experimental results.展开更多
Solder joint quality inspection is a crucial step in the qualification inspection of printed circuit board(PCB)components,and efficient and accurate inspection methods will greatly improve its production efficiency.In...Solder joint quality inspection is a crucial step in the qualification inspection of printed circuit board(PCB)components,and efficient and accurate inspection methods will greatly improve its production efficiency.In this paper,we propose a PCB solder joint quality detection algorithm based on a lightweight classification network.First,the Select Joint segmentation method was used to obtain the solder joint information,and colour space conversion was used to locate the solder joint.The mask method,contour detection,and box line method were combined to complete the extraction of solder joint information.Then,by combining the respective characteristics of convolutional neural network and Transformer and introducing Cross-covariance attention to reduce the computational complexity and resource consumption of the model and evenly distribute the global view mutual information in the whole training process,a new lightweight network model MobileXT is proposed to complete defect classification.Only 16.4%of the Vision Transformer computing resources used in this model can achieve an average accuracy improvement of 31%.Additionally,the network is trained and validated using a dataset of 1804 solder joint images constructed from 93 PCB images and two external datasets to evaluate MobileXT performance.The proposed method achieves more effi-cient localization of the solder joint information and more accurate classification of weld joint defects,and the lightweight model design is more appropriate for industrial edge device deployments.展开更多
Sustainable and resilient pavement infrastructure is critical for current economic and environmental challenges.In the past 10 years,the pavement infrastructure strongly supports the rapid development of the global so...Sustainable and resilient pavement infrastructure is critical for current economic and environmental challenges.In the past 10 years,the pavement infrastructure strongly supports the rapid development of the global social economy.New theories,new methods,new technologies and new materials related to pavement engineering are emerging.Deterioration of pavement infrastructure is a typical multi-physics problem.Because of actual coupled behaviors of traffic and environmental conditions,predictions of pavement service life become more and more complicated and require a deep knowledge of pavement material analysis.In order to summarize the current and determine the future research of pavement engineering,Journal of Traffic and Transportation Engineering(English Edition)has launched a review paper on the topic of"New innovations in pavement materials and engineering:A review on pavement engineering research 2021".Based on the joint-effort of 43 scholars from 24 well-known universities in highway engineering,this review paper systematically analyzes the research status and future development direction of 5 major fields of pavement engineering in the world.The content includes asphalt binder performance and modeling,mixture performance and modeling of pavement materials,multi-scale mechanics,green and sustainable pavement,and intelligent pavement.Overall,this review paper is able to provide references and insights for researchers and engineers in the field of pavement engineering.展开更多
Waste cooking oil(WCO)has received attention on rejuvenating aged asphalt binder widely in recent years.This study evaluated the rejuvenation effects of WCO on aged asphalt binder on the micro-scale using molecular dy...Waste cooking oil(WCO)has received attention on rejuvenating aged asphalt binder widely in recent years.This study evaluated the rejuvenation effects of WCO on aged asphalt binder on the micro-scale using molecular dynamics(MD)simulation.First,the representative molecules of WCO and asphalt binders were selected.The molecular mixture model was then developed.The thermodynamic properties were investigated,including density,cohesive energy density,solubility parameter,and surface free energy.The results show that WCO can restore the thermodynamic properties of aged asphalt binder to some extent and WCO has different influences on electrostatic interactions and van der Waals effects.From the diffusion behavior and molecular structure of asphalt binder,WCO can improve the molecular mobility and restore the colloidal structure.Besides,the adhesion work and moisture susceptibility of asphalt binder-aggregate interfaces(calcite and quartz)were evaluated.The results show that WCO can improve adhesion work between asphalt binder and aggregates since WCO can change molecular structure of asphalt binders and certain adhesion work exists between WCO and aggregates.Also,it can mitigate the moisture susceptibility of asphalt binder-aggregate interfaces(calcite and quartz).The study demonstrates that the MD simulation can help to understand the rejuvenation effects of WCO on aged asphalt binder on the micro-scale.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities(DUT20JC50,DUT17RC(3)006)the National Natural Science Foundation of China(51508137)the Research Center of Civil Aviation Airport Safety and Operation Engineering Technology(KFKT2021-01)。
文摘The Portland cement concrete pavement(PCCP)often suffers from different environmental distresses and vehicle load failure,resulting in slab corner fractures,potholes,and other diseases.Rapid repair has become one of the effective ways to open traffic rapidly.In this study,a novel type of rapid repair material,basalt fiber reinforced polymer modified magnesium phosphate cement(BFPMPC),is used to rapidly repair PCCP.Notably,the mechanical properties and characteristics of the repair interfaces which are named interfacial transition zones(ITZs)formed by BFPMPC and cement concrete are focused on as a decisive factor for the performance of the rapid repair.The changing trend of the elastic moduli was studied by nanoindentation experiments in the ITZs with the deconvolution analysis that the elastic moduli of certain kinds of substances can be determined.The experimental results show that the elastic modulus of ITZ-1 with a width of about20μm can be regarded as 0.098 times of the aggregate,and 0.51 times of the ordinary Portland cement(OPC)mortar.The BFPMPC-OPC mortar ITZ has roughly the same mechanical properties as the ITZ between aggregate and BFPMPC.A multi-scale representative two-dimensional model was established by random aggregate and a two-dimensional extended finite element method(XFEM)to study the mechanical properties of the repair interface.The simulation results show that the ITZ formed by the interface of BFPMPC and OPC mortar and basalt aggregate is the most vulnerable to failure,which is consistent with the nano-indentation experimental results.
基金National Natural Science Foundation of China,Grant/Award Numbers:62272418,62102058Basic Public Welfare Research Program of Zhejiang Province,Grant/Award Number:LGG18E050011。
文摘Solder joint quality inspection is a crucial step in the qualification inspection of printed circuit board(PCB)components,and efficient and accurate inspection methods will greatly improve its production efficiency.In this paper,we propose a PCB solder joint quality detection algorithm based on a lightweight classification network.First,the Select Joint segmentation method was used to obtain the solder joint information,and colour space conversion was used to locate the solder joint.The mask method,contour detection,and box line method were combined to complete the extraction of solder joint information.Then,by combining the respective characteristics of convolutional neural network and Transformer and introducing Cross-covariance attention to reduce the computational complexity and resource consumption of the model and evenly distribute the global view mutual information in the whole training process,a new lightweight network model MobileXT is proposed to complete defect classification.Only 16.4%of the Vision Transformer computing resources used in this model can achieve an average accuracy improvement of 31%.Additionally,the network is trained and validated using a dataset of 1804 solder joint images constructed from 93 PCB images and two external datasets to evaluate MobileXT performance.The proposed method achieves more effi-cient localization of the solder joint information and more accurate classification of weld joint defects,and the lightweight model design is more appropriate for industrial edge device deployments.
基金National Key R&D Program of China(No.2018YFB1600200,2021YFB1600200)National Natural Science Foundation of China(No.51608457,51778038,51808016,51808403,51908057,51908072,51908165,51908331,52008029,52008069,52078018,52078025,52078049,52078209,52108403,52122809,52178417)+9 种基金Marie Sk?odowska-Curie Individual Fellowships of the European Commission’s Horizon 2020 programme(No.101024139)Natural Science Foundation of Heilongjiang Province(No.JJ2020ZD0015)China Postdoctoral Science Foundation funded project(No.BX20180088)Research Capability Enhancement Program for Young Professors of Beijing University of Civil Engineering and Architecture(No.02080921021)Young Scholars of Beijing Talent Program(No.02082721009)Beijing Municipal Natural Science Foundation and Beijing Municipal Education Commission(No.KZ201910016017)German Research Foundation(No.OE 514/15-1(459436571))Fundamental Research Funds for the Central Universities(No.2020kfyXJJS127)Marie Sk?odowska-Curie Individual Fellowships of the European Commission’s Horizon 2020 Programme(No.101030767)Research Fund for High Level Talent Program(No.22120210108)。
文摘Sustainable and resilient pavement infrastructure is critical for current economic and environmental challenges.In the past 10 years,the pavement infrastructure strongly supports the rapid development of the global social economy.New theories,new methods,new technologies and new materials related to pavement engineering are emerging.Deterioration of pavement infrastructure is a typical multi-physics problem.Because of actual coupled behaviors of traffic and environmental conditions,predictions of pavement service life become more and more complicated and require a deep knowledge of pavement material analysis.In order to summarize the current and determine the future research of pavement engineering,Journal of Traffic and Transportation Engineering(English Edition)has launched a review paper on the topic of"New innovations in pavement materials and engineering:A review on pavement engineering research 2021".Based on the joint-effort of 43 scholars from 24 well-known universities in highway engineering,this review paper systematically analyzes the research status and future development direction of 5 major fields of pavement engineering in the world.The content includes asphalt binder performance and modeling,mixture performance and modeling of pavement materials,multi-scale mechanics,green and sustainable pavement,and intelligent pavement.Overall,this review paper is able to provide references and insights for researchers and engineers in the field of pavement engineering.
基金financially supported by the Fundamental Research Funds for the Central Universities(Grant Nos.DUT20JC50 and DUT17RC(3)006)National Natural Science Foundation of China(Grant No.51508137)support of Network and Information Center of Dalian University of Technology for Materials Studio 7.0。
文摘Waste cooking oil(WCO)has received attention on rejuvenating aged asphalt binder widely in recent years.This study evaluated the rejuvenation effects of WCO on aged asphalt binder on the micro-scale using molecular dynamics(MD)simulation.First,the representative molecules of WCO and asphalt binders were selected.The molecular mixture model was then developed.The thermodynamic properties were investigated,including density,cohesive energy density,solubility parameter,and surface free energy.The results show that WCO can restore the thermodynamic properties of aged asphalt binder to some extent and WCO has different influences on electrostatic interactions and van der Waals effects.From the diffusion behavior and molecular structure of asphalt binder,WCO can improve the molecular mobility and restore the colloidal structure.Besides,the adhesion work and moisture susceptibility of asphalt binder-aggregate interfaces(calcite and quartz)were evaluated.The results show that WCO can improve adhesion work between asphalt binder and aggregates since WCO can change molecular structure of asphalt binders and certain adhesion work exists between WCO and aggregates.Also,it can mitigate the moisture susceptibility of asphalt binder-aggregate interfaces(calcite and quartz).The study demonstrates that the MD simulation can help to understand the rejuvenation effects of WCO on aged asphalt binder on the micro-scale.