Currently,welding quality detection remains dependent on manual operation,while the increase in the span and intricacy of steel bridges has rendered the conventional method of detection insufficient to fulfill the eng...Currently,welding quality detection remains dependent on manual operation,while the increase in the span and intricacy of steel bridges has rendered the conventional method of detection insufficient to fulfill the engineering requirements.This paper presents a systematic study of welding quality detection of steel bridges based on fusion of point clouds and images in complex construction environments.(1)A welding detection system is developed that could filter out stray light and capture weld images.(2)This paper enhances the centerline extraction method in 3D reconstruction,which could effectively filter out noise interference and precisely reconstruct weld contours.The contour dimensions of both filler and cover welds are identified through feature point extraction,with an estimated detection error under 0.6%.(3)This paper optimizes the feature extraction of the Faster R-CNN network based on the appearance feature and detection need of welding defects,resulting in an improvement of 28.3 in mAP.Experimental results demonstrate that the proposed welding quality detection is both efficient and accurate,and is capable of meeting the requirements of actual steel bridge construction.展开更多
Aggregation-induced emission(AIE)is a fascinating luminescence phenomenon that provides new ideas for developing new fluorescent devices.However,research on photofunctional complexes with AIE properties is still in it...Aggregation-induced emission(AIE)is a fascinating luminescence phenomenon that provides new ideas for developing new fluorescent devices.However,research on photofunctional complexes with AIE properties is still in its infancy,mainly because the motion of the AIE molecules that can move freely will be greatly restricted after immobilization in the complex.Therefore,extending the AIE properties of organic molecules to their constructed complexes has been difficult.展开更多
英语复杂介词应界定为词还是短语,学界未有定论。本文以构式化理论为视角,借助语义向量空间的定量方法,考察临界复杂介词in the face of的固化过程。本研究发现:1)在过去200年间,该构式的能产性和图式性增加,而组构性降低。从基于使用...英语复杂介词应界定为词还是短语,学界未有定论。本文以构式化理论为视角,借助语义向量空间的定量方法,考察临界复杂介词in the face of的固化过程。本研究发现:1)在过去200年间,该构式的能产性和图式性增加,而组构性降低。从基于使用的视角来看,这种变化趋势不仅反映了构式固化程度的增强,同时也表明其逐渐向介词范畴的演进;2)该构式的固化过程并不是单向的线性发展,而是表现为构式节点间横向和纵向关系的变化;3)该构式固化的动因有二:一是高能产性导致的组块效应,二是识解层面的语义简化。展开更多
A substituted pyridazine was used to construct a family of mononuclear heteroleptic complexes[Ln(tta)_(3)(dppn)],Ln=Pr-Lu;Htta=thenoyltrifluoroacetone;dppn=3,6-di(2-pyridyl)pyridazine.All the complexes obtained were c...A substituted pyridazine was used to construct a family of mononuclear heteroleptic complexes[Ln(tta)_(3)(dppn)],Ln=Pr-Lu;Htta=thenoyltrifluoroacetone;dppn=3,6-di(2-pyridyl)pyridazine.All the complexes obtained were characterized by CHN elemental analysis,NMR spectroscopy,ESI mass spectrometry,FTIR spectroscopy and single crystal X-ray analysis.The photophysical properties of lanthanide complexes were carefully investigated,and the dppn ligand was found to act as a chromophore centre to sensitize metal-centred emission of the Nd,Sm,Eu,and Yb complexes under UV excitation.It has been shown that a powder sample of the Eu complex can contain two isomers with somewhat different symmetries of the environment of the metallocentre.The mechanism for the emission of luminescent Nd,Sm,Eu,and Yb complexes was investigated by TDDFT calculations and the results confirmed the conclusion made on the basis of experimental data regarding the likely pathway of energy transfer from the chromophore centre to the emissive level of Ln(III).展开更多
At present,as the majority of nursing homes,resorts,villages,villas and other decentralized living areas are far away from municipal sewer system,it is difficult to transport municipal waste water to city sewage treat...At present,as the majority of nursing homes,resorts,villages,villas and other decentralized living areas are far away from municipal sewer system,it is difficult to transport municipal waste water to city sewage treatment plants for processing.If the large quantity of decentralized wastewater were directly discharged to the rivers,lakes or other receiving water body without treatment,seriously contaminate to surface water and groundwater occurred.展开更多
Three-dimensional(3D)printing allows for the construction of complex structures.However,3D-printing vertical structures with a high aspect ratio remains a pending challenge,especially when a high lateral resolution is...Three-dimensional(3D)printing allows for the construction of complex structures.However,3D-printing vertical structures with a high aspect ratio remains a pending challenge,especially when a high lateral resolution is required.Here,to address this challenge,we propose and demonstrate micro-3D sculptured metastructures with deep trenches of 1:4(width:height)aspect ratio for sub-10µm resolution.Our construction relies on two-photon polymerization for a 3D-pattern with its trenches,followed by electroplating of a thick metal film and its dry etching to remove the seed layer.To test the proposed fabrication process,we built up three-dimensional RF metastructures showcasing the depth effect as the third dimension.Using the numerical solutions,we custom-tailored these metastructure resonators to fall within a specific resonance frequency range of 4-6 GHz while undertaking comparative analyses regarding overall footprint,quality factor,and resonance frequency shift as a function of their cross-sectional aspect ratio.The proposed process flow is shown to miniaturize metal footprint and tune the resonance frequency of these thick 3Dmetastructures while increasing their quality factor.These experimental findings indicate that this method of producing trenches via 3D-printing provides rich opportunities to implement high-aspect-ratio,complex structures.展开更多
基金supported by the National Natural Science Foundation of China(72071043)the National Key R&D Program of China(2021YFF0500904).
文摘Currently,welding quality detection remains dependent on manual operation,while the increase in the span and intricacy of steel bridges has rendered the conventional method of detection insufficient to fulfill the engineering requirements.This paper presents a systematic study of welding quality detection of steel bridges based on fusion of point clouds and images in complex construction environments.(1)A welding detection system is developed that could filter out stray light and capture weld images.(2)This paper enhances the centerline extraction method in 3D reconstruction,which could effectively filter out noise interference and precisely reconstruct weld contours.The contour dimensions of both filler and cover welds are identified through feature point extraction,with an estimated detection error under 0.6%.(3)This paper optimizes the feature extraction of the Faster R-CNN network based on the appearance feature and detection need of welding defects,resulting in an improvement of 28.3 in mAP.Experimental results demonstrate that the proposed welding quality detection is both efficient and accurate,and is capable of meeting the requirements of actual steel bridge construction.
基金supported by the National Natural Science Foundation of China(Project No.22061047)The Ten Thousand Talent Plans for Young Top-notch Talents of Yunnan Province(No.YNWR-QNBJ-2019-088)the Yunnan University’s Research Innovation Fund for Graduate Students(No.2021Z107).
文摘Aggregation-induced emission(AIE)is a fascinating luminescence phenomenon that provides new ideas for developing new fluorescent devices.However,research on photofunctional complexes with AIE properties is still in its infancy,mainly because the motion of the AIE molecules that can move freely will be greatly restricted after immobilization in the complex.Therefore,extending the AIE properties of organic molecules to their constructed complexes has been difficult.
文摘英语复杂介词应界定为词还是短语,学界未有定论。本文以构式化理论为视角,借助语义向量空间的定量方法,考察临界复杂介词in the face of的固化过程。本研究发现:1)在过去200年间,该构式的能产性和图式性增加,而组构性降低。从基于使用的视角来看,这种变化趋势不仅反映了构式固化程度的增强,同时也表明其逐渐向介词范畴的演进;2)该构式的固化过程并不是单向的线性发展,而是表现为构式节点间横向和纵向关系的变化;3)该构式固化的动因有二:一是高能产性导致的组块效应,二是识解层面的语义简化。
文摘A substituted pyridazine was used to construct a family of mononuclear heteroleptic complexes[Ln(tta)_(3)(dppn)],Ln=Pr-Lu;Htta=thenoyltrifluoroacetone;dppn=3,6-di(2-pyridyl)pyridazine.All the complexes obtained were characterized by CHN elemental analysis,NMR spectroscopy,ESI mass spectrometry,FTIR spectroscopy and single crystal X-ray analysis.The photophysical properties of lanthanide complexes were carefully investigated,and the dppn ligand was found to act as a chromophore centre to sensitize metal-centred emission of the Nd,Sm,Eu,and Yb complexes under UV excitation.It has been shown that a powder sample of the Eu complex can contain two isomers with somewhat different symmetries of the environment of the metallocentre.The mechanism for the emission of luminescent Nd,Sm,Eu,and Yb complexes was investigated by TDDFT calculations and the results confirmed the conclusion made on the basis of experimental data regarding the likely pathway of energy transfer from the chromophore centre to the emissive level of Ln(III).
文摘At present,as the majority of nursing homes,resorts,villages,villas and other decentralized living areas are far away from municipal sewer system,it is difficult to transport municipal waste water to city sewage treatment plants for processing.If the large quantity of decentralized wastewater were directly discharged to the rivers,lakes or other receiving water body without treatment,seriously contaminate to surface water and groundwater occurred.
基金the financial support in part from TUBITAK 20AG001,and 121C266HVD also acknowledges the support from TUBA and TUBITAK 2247-A National Leader Researchers Program(121C266)。
文摘Three-dimensional(3D)printing allows for the construction of complex structures.However,3D-printing vertical structures with a high aspect ratio remains a pending challenge,especially when a high lateral resolution is required.Here,to address this challenge,we propose and demonstrate micro-3D sculptured metastructures with deep trenches of 1:4(width:height)aspect ratio for sub-10µm resolution.Our construction relies on two-photon polymerization for a 3D-pattern with its trenches,followed by electroplating of a thick metal film and its dry etching to remove the seed layer.To test the proposed fabrication process,we built up three-dimensional RF metastructures showcasing the depth effect as the third dimension.Using the numerical solutions,we custom-tailored these metastructure resonators to fall within a specific resonance frequency range of 4-6 GHz while undertaking comparative analyses regarding overall footprint,quality factor,and resonance frequency shift as a function of their cross-sectional aspect ratio.The proposed process flow is shown to miniaturize metal footprint and tune the resonance frequency of these thick 3Dmetastructures while increasing their quality factor.These experimental findings indicate that this method of producing trenches via 3D-printing provides rich opportunities to implement high-aspect-ratio,complex structures.
