Beetle wings are very specialized flight organs consisting of the veins and membranes.Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally.In the present ...Beetle wings are very specialized flight organs consisting of the veins and membranes.Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally.In the present study,we have used a Digital Image Correlation (DIC) technique to measure the elastic modulus of a beetle wing membrane.Specimens were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm).We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing membrane.The specimen was attached to a designed fixture to induce a uniform displacement by means of a micromanipulator.We used an ARAMISTM system based on the digital image correlation technique to measure the corresponding displacement of a specimen.The thickness of the beetle wing varied at different points of the membrane.The elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy;the elastic modulus in the chordwise direction is approximately 2.65 GPa,which is three times larger than the elastic modulus in the spanwise direction of 0.84 GPa.As a result,the digital image correlation-based ARAMIS system was suc- cessfully used to measure the elastic modulus of a beetle wing.In addition to membrane's elastic modulus,we considered the Poisson's ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile machine.The result reveals the Poisson's ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.展开更多
This work is dedicated to the experimental study of the shear properties of three-dimensional reinforced composites taking into account their structural features,in Iosipescu tests.Shear strains have been determined u...This work is dedicated to the experimental study of the shear properties of three-dimensional reinforced composites taking into account their structural features,in Iosipescu tests.Shear strains have been determined using Vic-3D non-contact three-dimensional digital optical system.The evolution of inhomogeneous strain fields on the surface of composite specimens of the structure under study has been analyzed.The variants of strain averaging in the specimen working area have been analyzed using Vic-3D tools.AMSY-6 acoustic emission system has been used to assess the structural integrity of composite materials under loading.展开更多
We present a 3D inversion method to recover density distribution from gravity data in space domain.Our method firstly employs 3D correlation image of the vertical gradient of gravity data as a starting model to genera...We present a 3D inversion method to recover density distribution from gravity data in space domain.Our method firstly employs 3D correlation image of the vertical gradient of gravity data as a starting model to generate a higher resolution image for inversion.The 3D density distribution is then obtained by inverting the correlation image of gravity data to fit the observed data based on classical inversion method of the steepest descent method.We also perform the effective equivalent storage and subdomain techniques in the starting model calculation,the forward modeling and the inversion procedures,which allow fast computation in space domain with reducing memory consumption but maintaining accuracy.The efficiency and stability of our method is demonstrated on two sets of synthetic data and one set of the Northern Sinai Peninsula gravity data.The inverted 3D density distributions show that high density bodies beneath Risan Aniza and low density bodies exist to the southeast of Risan Aniza at depths between 1~10 and 20 km,which may be originated from hot anomalies in the lower crust.The results show that our inversion method is useful for 3D quantitative interpretation.展开更多
Using the source imaging technique in two-pion interferometry,we study the image of the hydrodynamic particle-emitting source with the HIJING initial conditions for relativistic heavy-ion collisions on an event-by-eve...Using the source imaging technique in two-pion interferometry,we study the image of the hydrodynamic particle-emitting source with the HIJING initial conditions for relativistic heavy-ion collisions on an event-by-event basis.It is shown that the initial-state fluctuations may give rise to bumpy structures of the medium during hydrodynamical evolution,which affects the two-pion emission space and leads to a visible two-tiered shape in the source function imaged using the two-pion Bose–Einstein correlations.This two-tiered shape can be understood within a similar but more analytic granular source model and is found to be closely related to the introduced quantity n,which characterizes the granular inhomogeneity of the source.By fitting the imaged source function with a granular source parametrization,we extract the granular inhomogeneity of the hydrodynamic source,which is found to be sensitive to both the Gaussian smearing width of the HIJING initial condition and the centrality of the collisions.展开更多
In this paper,an improved optical flow method for image registration is proposed.It is novel in the way that it improves the optical flow method with an initial motion estimator:extended phase correlation technique(EP...In this paper,an improved optical flow method for image registration is proposed.It is novel in the way that it improves the optical flow method with an initial motion estimator:extended phase correlation technique(EPCT),using merits of the latter to compensate deficiencies of the former.In a more detailed manner,it can be said that the optical flow method can reach the sub-pixel accuracy and calculate complex distortion patterns like chirping and tilting but is weak with large-scale movements.Because EPCT covers measurements of large translations and rotations with pixel level accuracy and is efficient in the calculating load,it can be treated as a good initial motion estimator for optical flow method.Tests have proved that this improved method will significantly enhance the registration performance,especially,for images with large-scale movements and robust against random noises.展开更多
Log-polar transformation(LPT)is widely used in image registration due to its scale and rotation invariant properties.Through LPT,rotation and scale transformation can be made into translation displacement in log-polar...Log-polar transformation(LPT)is widely used in image registration due to its scale and rotation invariant properties.Through LPT,rotation and scale transformation can be made into translation displacement in log-polar coordinates,and phase correlation technique can be used to get the displacement.In LPT based image registration,constant samples in digitalization processing produce less precise and effective results.Thus,dynamic log-polar transformation(DLPT)is used in this paper.DLPT is a method that generates several sample sets in axes to produce several results and only the effective results are used to get the final results by using statistical approach.Therefore,DLPT can get more precise and effective transformation results than the conventional LPT.Mutual information(MI)is a similarity measure to align two images and has been used in image registration for a long time.An optimal transform for image registration can be obtained by maximizing MI between the two images.Image registration based on MI is robust in noisy,occlusion and illumination changing circumstance.In this paper,we study image registration using MI and DLPT.Experiments with digitalizing images and with real image datasets are performed,and the experimental results show that the combination of MI with DLPT is an effective and precise method for image registration.展开更多
Particle size and shape characteristics are commonly measured with two-dimensional(2D)imaging techniques,two of which are static or dynamic imaging techniques.These 2D particle characteristics need to be applied to pa...Particle size and shape characteristics are commonly measured with two-dimensional(2D)imaging techniques,two of which are static or dynamic imaging techniques.These 2D particle characteristics need to be applied to particulate processes where they model three-dimensional(3D)processes.The correlation between 2D and 3D particle characteristics is therefore necessary,but the knowledge is still limited to either mathematically simple shapes or specific sets of investigated bulk solids.A particle dataset consisting of six bulk solids measured with X-ray microscopy was used to simulate the results of 2D imaging techniques to create a dataset to test the correlation between sets of particle characteristics.The dataset thus created offers the possibility to study the correlation between characteristic values and robustly predict the 3D properties of bulk solids measured with 2D measurement techniques.Several correlations are determined.These include predictive equations for Wadell's sphericity(3D)from 2D shape factors and particle width(3D)from Feret diameters(2D).The correlations have been validated with dynamic image analysis measurements.The correlations allow the practitioner in principle to predict particle sphericity and sieve size distribution from dynamic image analysis for compact particles.展开更多
MAG(metal active gas)焊接是常用的不锈钢焊缝补焊工艺。为探究MAG补焊对轨道车辆电气箱体用06Cr19Ni10不锈钢接头力学性能的影响,首先,设计并开展了原始焊缝(AW)、补焊区域(RW)及补焊外部区域(ERW)试样金相试验、显微硬度测试和拉伸试...MAG(metal active gas)焊接是常用的不锈钢焊缝补焊工艺。为探究MAG补焊对轨道车辆电气箱体用06Cr19Ni10不锈钢接头力学性能的影响,首先,设计并开展了原始焊缝(AW)、补焊区域(RW)及补焊外部区域(ERW)试样金相试验、显微硬度测试和拉伸试验,利用数字图像相关技术获取了拉伸过程中试样表面应变场演化;然后,采用场发射扫描电子显微镜分析了拉伸断裂机理;最后,通过二值化量化了补焊对轫脆转变的影响。研究结果表明:补焊试样中存在明显的二次熔合线,多次的热输入导致树枝状铁素体增多;补焊试样焊缝根部由于补焊坡口较小,其硬度总体偏高,焊缝顶端铁素体发生重结晶,其焊缝硬度高于热影响区;受补焊影响,补焊及外部区域焊缝试样在拉伸过程中具有较大的局部应变,其中,补焊试样抗拉强度增大,屈服强度减小,在3种试样中屈强比最低,具有较好的塑性;与其他试样不同,由于焊缝根部性能减弱,补焊外部区域试样整体拉伸性能最弱,且由于晶界结合力减弱,表现出脆性断裂特征。展开更多
Tungsten inert gas （TIG） welded joints for 2219-T87 aluminum alloy are often used in the fuel tanks of large launch vehicles. Because of the massive loads these vehicles carry, dealing with weld reinforcement on TIG...Tungsten inert gas （TIG） welded joints for 2219-T87 aluminum alloy are often used in the fuel tanks of large launch vehicles. Because of the massive loads these vehicles carry, dealing with weld reinforcement on TIG joints represents an important issue in their manufacturing and strength evaluation. Experimental and numerical simulation methods were used to investigate the effects of weld toe shape and weld toe position on the tensile behavior and mechanical properties of these joints. The simulation results indicated that the relative difference in elongation could be as large as 96.9% caused by the difference in weld toe shape. The joints with weld toes located in the weld metal or in the partially melted zone （PMZ） exhibited larger elongation than joints with weld toes located at the juncture of the weld metal and the PMZ.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF)the Ministry of Education, Science and Technology (Grant number: 2009-0083068)
文摘Beetle wings are very specialized flight organs consisting of the veins and membranes.Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally.In the present study,we have used a Digital Image Correlation (DIC) technique to measure the elastic modulus of a beetle wing membrane.Specimens were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm).We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing membrane.The specimen was attached to a designed fixture to induce a uniform displacement by means of a micromanipulator.We used an ARAMISTM system based on the digital image correlation technique to measure the corresponding displacement of a specimen.The thickness of the beetle wing varied at different points of the membrane.The elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy;the elastic modulus in the chordwise direction is approximately 2.65 GPa,which is three times larger than the elastic modulus in the spanwise direction of 0.84 GPa.As a result,the digital image correlation-based ARAMIS system was suc- cessfully used to measure the elastic modulus of a beetle wing.In addition to membrane's elastic modulus,we considered the Poisson's ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile machine.The result reveals the Poisson's ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.
基金the Russian Foundation for Basic Research within the Projects(Grants 19-31-90148 and 18-01-00763)The experimental studies of shear material properties were conducted within the State Assignment of the Ministry of Education and Science of the Russian Federation(9.7529.2017/9.10).
文摘This work is dedicated to the experimental study of the shear properties of three-dimensional reinforced composites taking into account their structural features,in Iosipescu tests.Shear strains have been determined using Vic-3D non-contact three-dimensional digital optical system.The evolution of inhomogeneous strain fields on the surface of composite specimens of the structure under study has been analyzed.The variants of strain averaging in the specimen working area have been analyzed using Vic-3D tools.AMSY-6 acoustic emission system has been used to assess the structural integrity of composite materials under loading.
基金the Institute of Crustal Dynamics,China Earthquake Administration(Grant No.ZDJ2019-09)the National Science Foundation of China(Grant No.41704086)the National Key Research&Development Program(2016YFC060110401).
文摘We present a 3D inversion method to recover density distribution from gravity data in space domain.Our method firstly employs 3D correlation image of the vertical gradient of gravity data as a starting model to generate a higher resolution image for inversion.The 3D density distribution is then obtained by inverting the correlation image of gravity data to fit the observed data based on classical inversion method of the steepest descent method.We also perform the effective equivalent storage and subdomain techniques in the starting model calculation,the forward modeling and the inversion procedures,which allow fast computation in space domain with reducing memory consumption but maintaining accuracy.The efficiency and stability of our method is demonstrated on two sets of synthetic data and one set of the Northern Sinai Peninsula gravity data.The inverted 3D density distributions show that high density bodies beneath Risan Aniza and low density bodies exist to the southeast of Risan Aniza at depths between 1~10 and 20 km,which may be originated from hot anomalies in the lower crust.The results show that our inversion method is useful for 3D quantitative interpretation.
基金the Research Start-up Funding of Hubei University of Education(No.201801)Hubei Provincial Natural Science Foundation of China(No.2020CFB697)+1 种基金the China Postdoctoral Science Foundation(No.2019M652929)the MOE Key Laboratory of Quark and Lepton Physics(Central China Normal University)(No.QLPL201802).
文摘Using the source imaging technique in two-pion interferometry,we study the image of the hydrodynamic particle-emitting source with the HIJING initial conditions for relativistic heavy-ion collisions on an event-by-event basis.It is shown that the initial-state fluctuations may give rise to bumpy structures of the medium during hydrodynamical evolution,which affects the two-pion emission space and leads to a visible two-tiered shape in the source function imaged using the two-pion Bose–Einstein correlations.This two-tiered shape can be understood within a similar but more analytic granular source model and is found to be closely related to the introduced quantity n,which characterizes the granular inhomogeneity of the source.By fitting the imaged source function with a granular source parametrization,we extract the granular inhomogeneity of the hydrodynamic source,which is found to be sensitive to both the Gaussian smearing width of the HIJING initial condition and the centrality of the collisions.
文摘In this paper,an improved optical flow method for image registration is proposed.It is novel in the way that it improves the optical flow method with an initial motion estimator:extended phase correlation technique(EPCT),using merits of the latter to compensate deficiencies of the former.In a more detailed manner,it can be said that the optical flow method can reach the sub-pixel accuracy and calculate complex distortion patterns like chirping and tilting but is weak with large-scale movements.Because EPCT covers measurements of large translations and rotations with pixel level accuracy and is efficient in the calculating load,it can be treated as a good initial motion estimator for optical flow method.Tests have proved that this improved method will significantly enhance the registration performance,especially,for images with large-scale movements and robust against random noises.
基金the National Natural Science Foundation of China(Nos.61440016,61273225 and 61201423)the Natural Science Foundation of Hubei Province(No.2014CFB247)
文摘Log-polar transformation(LPT)is widely used in image registration due to its scale and rotation invariant properties.Through LPT,rotation and scale transformation can be made into translation displacement in log-polar coordinates,and phase correlation technique can be used to get the displacement.In LPT based image registration,constant samples in digitalization processing produce less precise and effective results.Thus,dynamic log-polar transformation(DLPT)is used in this paper.DLPT is a method that generates several sample sets in axes to produce several results and only the effective results are used to get the final results by using statistical approach.Therefore,DLPT can get more precise and effective transformation results than the conventional LPT.Mutual information(MI)is a similarity measure to align two images and has been used in image registration for a long time.An optimal transform for image registration can be obtained by maximizing MI between the two images.Image registration based on MI is robust in noisy,occlusion and illumination changing circumstance.In this paper,we study image registration using MI and DLPT.Experiments with digitalizing images and with real image datasets are performed,and the experimental results show that the combination of MI with DLPT is an effective and precise method for image registration.
基金supported by the German Federal Ministry of Education and Research through the research project InfraDatRec(grant no.03XP0426A).
文摘Particle size and shape characteristics are commonly measured with two-dimensional(2D)imaging techniques,two of which are static or dynamic imaging techniques.These 2D particle characteristics need to be applied to particulate processes where they model three-dimensional(3D)processes.The correlation between 2D and 3D particle characteristics is therefore necessary,but the knowledge is still limited to either mathematically simple shapes or specific sets of investigated bulk solids.A particle dataset consisting of six bulk solids measured with X-ray microscopy was used to simulate the results of 2D imaging techniques to create a dataset to test the correlation between sets of particle characteristics.The dataset thus created offers the possibility to study the correlation between characteristic values and robustly predict the 3D properties of bulk solids measured with 2D measurement techniques.Several correlations are determined.These include predictive equations for Wadell's sphericity(3D)from 2D shape factors and particle width(3D)from Feret diameters(2D).The correlations have been validated with dynamic image analysis measurements.The correlations allow the practitioner in principle to predict particle sphericity and sieve size distribution from dynamic image analysis for compact particles.
文摘MAG(metal active gas)焊接是常用的不锈钢焊缝补焊工艺。为探究MAG补焊对轨道车辆电气箱体用06Cr19Ni10不锈钢接头力学性能的影响,首先,设计并开展了原始焊缝(AW)、补焊区域(RW)及补焊外部区域(ERW)试样金相试验、显微硬度测试和拉伸试验,利用数字图像相关技术获取了拉伸过程中试样表面应变场演化;然后,采用场发射扫描电子显微镜分析了拉伸断裂机理;最后,通过二值化量化了补焊对轫脆转变的影响。研究结果表明:补焊试样中存在明显的二次熔合线,多次的热输入导致树枝状铁素体增多;补焊试样焊缝根部由于补焊坡口较小,其硬度总体偏高,焊缝顶端铁素体发生重结晶,其焊缝硬度高于热影响区;受补焊影响,补焊及外部区域焊缝试样在拉伸过程中具有较大的局部应变,其中,补焊试样抗拉强度增大,屈服强度减小,在3种试样中屈强比最低,具有较好的塑性;与其他试样不同,由于焊缝根部性能减弱,补焊外部区域试样整体拉伸性能最弱,且由于晶界结合力减弱,表现出脆性断裂特征。
文摘Tungsten inert gas （TIG） welded joints for 2219-T87 aluminum alloy are often used in the fuel tanks of large launch vehicles. Because of the massive loads these vehicles carry, dealing with weld reinforcement on TIG joints represents an important issue in their manufacturing and strength evaluation. Experimental and numerical simulation methods were used to investigate the effects of weld toe shape and weld toe position on the tensile behavior and mechanical properties of these joints. The simulation results indicated that the relative difference in elongation could be as large as 96.9% caused by the difference in weld toe shape. The joints with weld toes located in the weld metal or in the partially melted zone （PMZ） exhibited larger elongation than joints with weld toes located at the juncture of the weld metal and the PMZ.
