为提高管道环焊缝超声衍射时差法(time of flight diffraction,TOFD)扫描图谱在背景信号干扰、样本量不均衡等情况下的缺陷识别效果,提出了一种改进的YOLOv5s网络模型.针对管道环焊缝TOFD图谱中缺陷形态不规则的特点,通过引入可变形卷积...为提高管道环焊缝超声衍射时差法(time of flight diffraction,TOFD)扫描图谱在背景信号干扰、样本量不均衡等情况下的缺陷识别效果,提出了一种改进的YOLOv5s网络模型.针对管道环焊缝TOFD图谱中缺陷形态不规则的特点,通过引入可变形卷积,使得网络自适应缺陷自身的形状特点,提高TOFD图谱中不规则缺陷的特征提取能力;针对TOFD扫描图谱中直通波和底面波等干扰波形对缺陷识别的影响,通过在网络不同深度分别添加自注意力机制,引导网络关注缺陷细微特征的同时抑制界面波对缺陷识别的影响;针对实际样本中各类缺陷不均衡的情况,采用SlideLoss损失函数代替原损失函数,提高网络对样本量较少的裂纹类缺陷的识别精度.对比试验结果表明,改进后的网络能够抑制TOFD图谱复杂背景干扰,提高样本不均衡条件下的识别率.相比原网络,整体平均识别率均值(mean Average Precision,mAP)和裂纹类缺陷的平均识别率(Average Precision,AP)分别提高了8.2%和7.3%.展开更多
能源动力、特种设备、航空航天、石油化工等领域的高端装备制造过程广泛采用焊接工艺,焊接质量检测是保障装备制造质量及其服役质量控制的关键环节。衍射时差法(Time of Flight Diffraction,TOFD)具有检测速度快、精度高、环保性好等优...能源动力、特种设备、航空航天、石油化工等领域的高端装备制造过程广泛采用焊接工艺,焊接质量检测是保障装备制造质量及其服役质量控制的关键环节。衍射时差法(Time of Flight Diffraction,TOFD)具有检测速度快、精度高、环保性好等优势,已成为当前焊缝质量检测的重要手段。然而,现有缺陷评定方式以人工分析为主,效率低、一致性差,严重制约了缺陷检测效率;同时,现有TOFD检测软件功能单一,以数据存储和基础处理为主,缺乏智能化分析能力,难以满足制造业数字化转型及数字化监管需求。因此,结合人工智能、计算机视觉处理等新一代信息技术,提出了“数据驱动+智能分析+云端协同”的TOFD焊缝缺陷检测新范式,定义了新范式下的TOFD智能检测技术内容。相关成果已在能源动力、特种设备等领域实现示范应用,显著提升了检测效率与数字化监管水平。展开更多
We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW...We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.展开更多
In oil and gas exploration,small-scale karst cavities and faults are important targets.The former often serve as reservoir space for carbonate reservoirs,while the latter often provide migration pathways for oil and g...In oil and gas exploration,small-scale karst cavities and faults are important targets.The former often serve as reservoir space for carbonate reservoirs,while the latter often provide migration pathways for oil and gas.Due to these differences,the classification and identification of karst cavities and faults are of great significance for reservoir development.Traditional seismic attributes and diffraction imaging techniques can effectively identify discontinuities in seismic images,but these techniques do not distinguish whether these discontinuities are karst cavities,faults,or other structures.It poses a challenge for seismic interpretation to accurately locate and classify karst cavities or faults within the seismic attribute maps and diffraction imaging profiles.In seismic data,the scattering waves are associated with small-scale scatters like karst cavities,while diffracted waves are seismic responses from discontinuous structures such as faults,reflector edges and fractures.In order to achieve classification and identification of small-scale karst cavities and faults in seismic images,we propose a diffraction classification imaging method which classifies diffracted and scattered waves in the azimuth-dip angle image matrix using a modified DenseNet.We introduce a coordinate attention module into DenseNet,enabling more precise extraction of dynamic and azimuthal features of diffracted and scattered waves in the azimuth-dip angle image matrix.Leveraging these extracted features,the modified DenseNet can produce reliable probabilities for diffracted/scattered waves,achieving high-accuracy automatic classification of cavities and faults based on diffraction imaging.The proposed method achieves 96%classification accuracy on the synthetic dataset.The field data experiment demonstrates that the proposed method can accurately classify small-scale faults and scatterers,further enhancing the resolution of diffraction imaging in complex geologic structures,and contributing to the localization of karstic fracture-cavern reservoirs.展开更多
When a laser beam is incident on a nonlinear grating with a laterally modulated second-order nonlinear coefficient,nonlinear diffraction of the noncollinear second-harmonic generation(SHG)signal occurs,with Raman–Nat...When a laser beam is incident on a nonlinear grating with a laterally modulated second-order nonlinear coefficient,nonlinear diffraction of the noncollinear second-harmonic generation(SHG)signal occurs,with Raman–Nath nonlinear diffraction(NRND)being a prominent example.As these SHG NRND processes involve coupling between the fundamental-wave pump laser vectorial field and the SHG laser vectorial field through the second-order nonlinearity secondrank tensor of the nonlinear crystal,the nonlinear interaction between light and the nonlinear grating can be manipulated by adjusting the polarization state of the pump laser.In this paper,we derive the relationship between the polarization state of the incident light and the generated nonlinear diffraction signal based on the nonlinear coupled wave equation and experimentally validate the predicted diffraction characteristics.The results show that the optical properties of each order of NRND are highly sensitive to the polarization angle of the incident pump laser beam.展开更多
Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditio...Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditional optical nanometry methods often rely on precision nanostructure fabrication,multi-beam interferometry,or complex post-processing algorithms,which can limit their practical use.In this study,we introduced a simplified and robust quantum measurement technique with an achievable resolution of 2.2 pm and an experimental demonstration of 1 nm resolution,distinguishing it from conventional interferometry,which depended on multiple reference beams.We designed a metasurface substrate with a mode-conversion function,in which an incident Gaussian beam is converted into higher-order transverse electromagnetic mode(TEM)modes.A theoretical analysis,including calculations of the Fisher information,demonstrated that the accuracy was maintained for nanoscale displacements.In conclusion,the study findings provide a new approach for precise alignment and metrology of nanofabrication and other advanced applications.展开更多
Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and ...Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and related deformation mechanisms is crucial for their structural applications,particularly in the lightweight transportation industries.Nevertheless,the underlying deformation mechanisms(e.g.,slip versus twinning)at each deformation stage during tension and compression have not been fully understood.In this study,we employed tensile and compressive tests on extruded Al and Mn containing Mg alloy,i.e.,an AM alloy Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca,during the synchrotron X-ray diffraction.Our results show that distinct deformation behaviors and mechanisms in tension and compression are associated with the strong texture in the extruded samples:(i)The tensile deformation is dominated by dislocation slips,with activation of non-basaland<c+a>slip,but deformation twinning is suppressed.(ii)The compressive deformation shows early-stage tensile twinning,followed by dislocation slips.Twinning induces grain reorientation,leading to significant lattice strain evolution aligned with the texture.The pronounced tension-compression asymmetry is attributed to the favorable shear stress direction formed in the twinning system during compression,which facilitates the activation of tensile twins.During tension,the strain hardening rate(SHR)drops significantly after yielding due to limited activated slip systems.In contrast,the samples under compression exhibit significant increases in SHR after yielding.During compression,dislocation multiplication dominates the initial strain hardening,while twinning progressively contributes more significantly than dislocation slip at higher strains.This study improves our understanding of the tension-compression and strain hardening asymmetries in extruded AM Mg alloys.展开更多
When a pump laser beam strikes the surface of a nonlinear crystal with modulated second-order nonlinearity,various nonlinear diffraction phenomena occur,with nonlinear Raman–Nath diffraction(NRND)being a prominent ex...When a pump laser beam strikes the surface of a nonlinear crystal with modulated second-order nonlinearity,various nonlinear diffraction phenomena occur,with nonlinear Raman–Nath diffraction(NRND)being a prominent example.In this study,we use an 800-nm Ti:sapphire femtosecond laser beam to pump the surface of a periodically poled lithium niobate(PPLN)crystal thin-plate nonlinear grating.By rotating the crystal,we change the incidence angle and observe and measure the exit angle,polarization,and power of NRND spots on the other side of the crystal.The experiment shows that NRND characteristics are highly sensitive to the incidence angle of the pump laser beam,which are consistent with the theoretical prediction.We expect that this research will advance the understanding of nonlinear diffraction and provide valuable insights for nonlinear optical interaction in complicated geometric and physical configurations.展开更多
文摘为提高管道环焊缝超声衍射时差法(time of flight diffraction,TOFD)扫描图谱在背景信号干扰、样本量不均衡等情况下的缺陷识别效果,提出了一种改进的YOLOv5s网络模型.针对管道环焊缝TOFD图谱中缺陷形态不规则的特点,通过引入可变形卷积,使得网络自适应缺陷自身的形状特点,提高TOFD图谱中不规则缺陷的特征提取能力;针对TOFD扫描图谱中直通波和底面波等干扰波形对缺陷识别的影响,通过在网络不同深度分别添加自注意力机制,引导网络关注缺陷细微特征的同时抑制界面波对缺陷识别的影响;针对实际样本中各类缺陷不均衡的情况,采用SlideLoss损失函数代替原损失函数,提高网络对样本量较少的裂纹类缺陷的识别精度.对比试验结果表明,改进后的网络能够抑制TOFD图谱复杂背景干扰,提高样本不均衡条件下的识别率.相比原网络,整体平均识别率均值(mean Average Precision,mAP)和裂纹类缺陷的平均识别率(Average Precision,AP)分别提高了8.2%和7.3%.
文摘能源动力、特种设备、航空航天、石油化工等领域的高端装备制造过程广泛采用焊接工艺,焊接质量检测是保障装备制造质量及其服役质量控制的关键环节。衍射时差法(Time of Flight Diffraction,TOFD)具有检测速度快、精度高、环保性好等优势,已成为当前焊缝质量检测的重要手段。然而,现有缺陷评定方式以人工分析为主,效率低、一致性差,严重制约了缺陷检测效率;同时,现有TOFD检测软件功能单一,以数据存储和基础处理为主,缺乏智能化分析能力,难以满足制造业数字化转型及数字化监管需求。因此,结合人工智能、计算机视觉处理等新一代信息技术,提出了“数据驱动+智能分析+云端协同”的TOFD焊缝缺陷检测新范式,定义了新范式下的TOFD智能检测技术内容。相关成果已在能源动力、特种设备等领域实现示范应用,显著提升了检测效率与数字化监管水平。
基金supported by the National Natural Science Foundation of China(Grant No.12105210)the Knowledge Innovation Program of Wuhan-Basi Research(Grant No.2023010201010149)。
文摘We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.
基金supported by Science Fund for Creative Research Groups of the National Natural Science Foundation of China,No.42321002。
文摘In oil and gas exploration,small-scale karst cavities and faults are important targets.The former often serve as reservoir space for carbonate reservoirs,while the latter often provide migration pathways for oil and gas.Due to these differences,the classification and identification of karst cavities and faults are of great significance for reservoir development.Traditional seismic attributes and diffraction imaging techniques can effectively identify discontinuities in seismic images,but these techniques do not distinguish whether these discontinuities are karst cavities,faults,or other structures.It poses a challenge for seismic interpretation to accurately locate and classify karst cavities or faults within the seismic attribute maps and diffraction imaging profiles.In seismic data,the scattering waves are associated with small-scale scatters like karst cavities,while diffracted waves are seismic responses from discontinuous structures such as faults,reflector edges and fractures.In order to achieve classification and identification of small-scale karst cavities and faults in seismic images,we propose a diffraction classification imaging method which classifies diffracted and scattered waves in the azimuth-dip angle image matrix using a modified DenseNet.We introduce a coordinate attention module into DenseNet,enabling more precise extraction of dynamic and azimuthal features of diffracted and scattered waves in the azimuth-dip angle image matrix.Leveraging these extracted features,the modified DenseNet can produce reliable probabilities for diffracted/scattered waves,achieving high-accuracy automatic classification of cavities and faults based on diffraction imaging.The proposed method achieves 96%classification accuracy on the synthetic dataset.The field data experiment demonstrates that the proposed method can accurately classify small-scale faults and scatterers,further enhancing the resolution of diffraction imaging in complex geologic structures,and contributing to the localization of karstic fracture-cavern reservoirs.
基金Project supported by Science and Technology Project of Guangdong(Grant No.2020B010190001)the National Natural Science Foundation of China(Grant No.12434016)National Funded Postdoctoral Researcher Program(Grant No.GZB20240785)。
文摘When a laser beam is incident on a nonlinear grating with a laterally modulated second-order nonlinear coefficient,nonlinear diffraction of the noncollinear second-harmonic generation(SHG)signal occurs,with Raman–Nath nonlinear diffraction(NRND)being a prominent example.As these SHG NRND processes involve coupling between the fundamental-wave pump laser vectorial field and the SHG laser vectorial field through the second-order nonlinearity secondrank tensor of the nonlinear crystal,the nonlinear interaction between light and the nonlinear grating can be manipulated by adjusting the polarization state of the pump laser.In this paper,we derive the relationship between the polarization state of the incident light and the generated nonlinear diffraction signal based on the nonlinear coupled wave equation and experimentally validate the predicted diffraction characteristics.The results show that the optical properties of each order of NRND are highly sensitive to the polarization angle of the incident pump laser beam.
基金supported by the West Light Project,CAS(xbzg-zdsys-202206)the National Key Research and Development Program of China(2021YFA1401003)+1 种基金the National Natural Science Foundation of China(NSFC)(62222513,U24A6010,and U24A20317)the Sichuan Engineering Research Center of Digital Materials.
文摘Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditional optical nanometry methods often rely on precision nanostructure fabrication,multi-beam interferometry,or complex post-processing algorithms,which can limit their practical use.In this study,we introduced a simplified and robust quantum measurement technique with an achievable resolution of 2.2 pm and an experimental demonstration of 1 nm resolution,distinguishing it from conventional interferometry,which depended on multiple reference beams.We designed a metasurface substrate with a mode-conversion function,in which an incident Gaussian beam is converted into higher-order transverse electromagnetic mode(TEM)modes.A theoretical analysis,including calculations of the Fisher information,demonstrated that the accuracy was maintained for nanoscale displacements.In conclusion,the study findings provide a new approach for precise alignment and metrology of nanofabrication and other advanced applications.
文摘Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and related deformation mechanisms is crucial for their structural applications,particularly in the lightweight transportation industries.Nevertheless,the underlying deformation mechanisms(e.g.,slip versus twinning)at each deformation stage during tension and compression have not been fully understood.In this study,we employed tensile and compressive tests on extruded Al and Mn containing Mg alloy,i.e.,an AM alloy Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca,during the synchrotron X-ray diffraction.Our results show that distinct deformation behaviors and mechanisms in tension and compression are associated with the strong texture in the extruded samples:(i)The tensile deformation is dominated by dislocation slips,with activation of non-basaland<c+a>slip,but deformation twinning is suppressed.(ii)The compressive deformation shows early-stage tensile twinning,followed by dislocation slips.Twinning induces grain reorientation,leading to significant lattice strain evolution aligned with the texture.The pronounced tension-compression asymmetry is attributed to the favorable shear stress direction formed in the twinning system during compression,which facilitates the activation of tensile twins.During tension,the strain hardening rate(SHR)drops significantly after yielding due to limited activated slip systems.In contrast,the samples under compression exhibit significant increases in SHR after yielding.During compression,dislocation multiplication dominates the initial strain hardening,while twinning progressively contributes more significantly than dislocation slip at higher strains.This study improves our understanding of the tension-compression and strain hardening asymmetries in extruded AM Mg alloys.
基金supported by the Science and Technology Project of Guangdong Province,China(Grant No.2020B010190001)the National Natural Science Foundation of China(Grant No.12434016)the National Funded Postdoctoral Researcher Program(Grant No.GZB20240785).
文摘When a pump laser beam strikes the surface of a nonlinear crystal with modulated second-order nonlinearity,various nonlinear diffraction phenomena occur,with nonlinear Raman–Nath diffraction(NRND)being a prominent example.In this study,we use an 800-nm Ti:sapphire femtosecond laser beam to pump the surface of a periodically poled lithium niobate(PPLN)crystal thin-plate nonlinear grating.By rotating the crystal,we change the incidence angle and observe and measure the exit angle,polarization,and power of NRND spots on the other side of the crystal.The experiment shows that NRND characteristics are highly sensitive to the incidence angle of the pump laser beam,which are consistent with the theoretical prediction.We expect that this research will advance the understanding of nonlinear diffraction and provide valuable insights for nonlinear optical interaction in complicated geometric and physical configurations.
