Lost Horizon tells a story about Shangri-La,a paradise in the Orient.Throughout the construction of the Oriental image in the novel,it can be found that under its representation of being enslaved,driven,marginalized a...Lost Horizon tells a story about Shangri-La,a paradise in the Orient.Throughout the construction of the Oriental image in the novel,it can be found that under its representation of being enslaved,driven,marginalized and silenced,it implies a three-dimensional flow mechanism with multiple power-relationships interwoven between Orient and Occident,insiders and outsiders,“civilized”and“uncivilized”,male and female,etc.Driven by this mechanism,the Oriental image is integrated under a single abstract label,which has become a way for the Occident to re-understand,reconstruct and express itself after the war.展开更多
Over recent years, Convolutional Neural Networks (CNN) has improved performance on practically every image-based task, including Content-Based Image Retrieval (CBIR). Nevertheless, since features of CNN have altered o...Over recent years, Convolutional Neural Networks (CNN) has improved performance on practically every image-based task, including Content-Based Image Retrieval (CBIR). Nevertheless, since features of CNN have altered orientation, training a CBIR system to detect and correct the angle is complex. While it is possible to construct rotation-invariant features by hand, retrieval accuracy will be low because hand engineering only creates low-level features, while deep learning methods build high-level and low-level features simultaneously. This paper presents a novel approach that combines a deep learning orientation angle detection model with the CBIR feature extraction model to correct the rotation angle of any image. This offers a unique construction of a rotation-invariant CBIR system that handles the CNN features that are not rotation invariant. This research also proposes a further study on how a rotation-invariant deep CBIR can recover images from the dataset in real-time. The final results of this system show significant improvement as compared to a default CNN feature extraction model without the OAD.展开更多
The purpose of this work was to demonstrate the feasibility of neurite orientation dispersion and density imaging(NODDI)in characterizing the brain tissue microstructural changes of middle cerebral artery occlusion(MC...The purpose of this work was to demonstrate the feasibility of neurite orientation dispersion and density imaging(NODDI)in characterizing the brain tissue microstructural changes of middle cerebral artery occlusion(MCAO)in rats at 3T MRI,and to validate NODDI metrics with histology.A multi-shell diffusion MRI protocol was performed on 11 MCAO rats and 10 control rats at different post-operation time points of 0.5,2,6,12,24 and 72 h.NODDI orientation dispersion index(ODI)and intracellular volume fraction(V_(ic))metrics were compared between MCAO group and control group.The evolution of NODDI metrics was characterized and validated by histology.Infarction was consistent with significantly increased ODI and V_(ic)in comparison to control tissues at all time points(P<0.001).Lesion ODI increased gradually from 0.5 to 72 h,while its V_(ic)showed a more complicated and fluctuated evolution.ODI and V_(ic)were significantly different between hyperacute and acute stroke periods(P<0.001).The NODDI metrics were found to be consistent with the histological findings.In conclusion,NODDI can reflect microstructural changes of brain tissues in MCAO rats at 3T MRI and the metrics are consistent with histology.This study helps to prepare NODDI for the diagnosis and management of ischemic stroke in translational research and clinical practice.展开更多
For vision-based mobile robot navigation, images of the same scene may undergo a general affine transformation in the case of significant viewpoint changes. So, a novel method for detecting affine invariant interest p...For vision-based mobile robot navigation, images of the same scene may undergo a general affine transformation in the case of significant viewpoint changes. So, a novel method for detecting affine invariant interest points is proposed to obtain the invariant local features, which is coined polynomial local orientation tensor(PLOT). The new detector is based on image local orientation tensor that is constructed from the polynomial expansion of image signal. Firstly, the properties of local orientation tensor of PLOT are analyzed, and a suitable tuning parameter of local orientation tensor is chosen so as to extract invariant features. The initial interest points are detected by local maxima search for the smaller eigenvalues of the orientation tensor. Then, an iterative procedure is used to allow the initial interest points to converge to affine invariant interest points and regions. The performances of this detector are evaluated on the repeatability criteria and recall versus 1-precision graphs, and then are compared with other existing approaches. Experimental results for PLOT show strong performance under affine transformation in the real-world conditions.展开更多
Theα+βtitanium alloy, Ti-6Al-4V, was welded by friction stir welding using a W-Re pin tool, and the defect-free weld was produced with proper welding parameters. Texture of the Ti-6Al-4V friction stir weld was stud...Theα+βtitanium alloy, Ti-6Al-4V, was welded by friction stir welding using a W-Re pin tool, and the defect-free weld was produced with proper welding parameters. Texture of the Ti-6Al-4V friction stir weld was studied by orientation imaging microscopy. The as-received Ti-6Al-4V sheet mill annealed was composed of elongated primary α and transformed β. A typical rolling texture was observed in the base material. The microstructure of the stir zone was significantly different from that of the base material. The stir zone was characterized by the presence of considerable amount of equiaxed dynamically recrystallized grains and a texture around{Ф1=30°,φ=62°,Ф2=30°}was developed during the friction stir welding.展开更多
The prevalence of neurodegenerative diseases is increasing as human longevity increases. The objective biomarkers that enable the staging and early diagnosis of neurodegenerative diseases are eagerly anticipated. It h...The prevalence of neurodegenerative diseases is increasing as human longevity increases. The objective biomarkers that enable the staging and early diagnosis of neurodegenerative diseases are eagerly anticipated. It has recently become possible to determine pathological changes in the brain without autopsy with the advancement of diffusion magnetic resonance imaging techniques. Diffusion magnetic resonance imaging is a robust tool used to evaluate brain microstructural complexity and integrity, axonal order, density, and myelination via the micron-scale displacement of water molecules diffusing in tissues. Diffusion tensor imaging, a type of diffusion magnetic resonance imaging technique is widely utilized in clinical and research settings;however, it has several limitations. To overcome these limitations, cutting-edge diffusion magnetic resonance imaging techniques, such as diffusional kurtosis imaging, neurite orientation dispersion and density imaging, and free water imaging, have been recently proposed and applied to evaluate the pathology of neurodegenerative diseases. This review focused on the main applications, findings, and future directions of advanced diffusion magnetic resonance imaging techniques in patients with Alzheimer's and Parkinson's diseases, the first and second most common neurodegenerative diseases, respectively.展开更多
During the last decades,advances in the understanding of genetic,cellular,and microstructural alterations associated to Huntington's disease(HD)have improved the understanding of this progressive and fatal illness...During the last decades,advances in the understanding of genetic,cellular,and microstructural alterations associated to Huntington's disease(HD)have improved the understanding of this progressive and fatal illness.However,events related to early neuropathological events,neuroinflammation,deterioration of neuronal connectivity and compensatory mechanisms still remain vastly unknown.Ultra-high field diffusion MRI(UHFD-MRI)techniques can contribute to a more comprehensive analysis of the early microstructural changes observed in HD.In addition,it is possible to evaluate if early imaging microstructural parameters might be linked to histological biomarkers.Moreover,qualitative studies analyzing histological complexity in brain areas susceptible to neurodegeneration could provide information on inflammatory events,compensatory increase of neuroconnectivity and mechanisms of brain repair and regeneration.The application of ultra-high field diffusion-MRI technology in animal models,particularly the R6/1 mice(a common preclinical mammalian model of HD),provide the opportunity to analyze alterations in a physiologically intact model of the disease.Although some disparities in volumetric changes across different brain structures between preclinical and clinical models has been documented,further application of different diffusion MRI techniques used in combination like diffusion tensor imaging,and neurite orientation dispersion and density imaging have proved effective in characterizing early parameters associated to alteration in water diffusion exchange within intracellular and extracellular compartments in brain white and grey matter.Thus,the combination of diffusion MRI imaging techniques and more complex neuropathological analysis could accelerate the discovery of new imaging biomarkers and the early diagnosis and neuromonitoring of patients affected with HD.展开更多
In feature based image matching,distinctive features in images are detected and represented by feature descriptors.Matching is then carried out by assessing the similarity of the descriptors of potentially conjugate p...In feature based image matching,distinctive features in images are detected and represented by feature descriptors.Matching is then carried out by assessing the similarity of the descriptors of potentially conjugate points.In this paper,we first shortly discuss the general frame-work.Then,we review feature detection as well as the determination of affine shape and orientation of local features,before analyzing feature description in more detail.In the feature description review,the general framework of local feature description is presented first.Then,the review discusses the evolution from hand-crafted feature descriptors,e.g.SIFT(Scale Invariant Feature Transform),to machine learning and deep learning based descriptors.The machine learning models,the training loss and the respective training data of learning-based algorithms are looked at in more detail;subsequently the various advantages and challenges of the different approaches are discussed.Finally,we present and assess some current research directions before concluding the paper.展开更多
Nanocontact properties of two-dimensional(2D)materials are closely dependent on their unique nanomechanical systems,such as the number of atomic layers and the supporting substrate.Here,we report a direct observation ...Nanocontact properties of two-dimensional(2D)materials are closely dependent on their unique nanomechanical systems,such as the number of atomic layers and the supporting substrate.Here,we report a direct observation of toplayer-dependent crystallographic orientation imaging of 2D materials with the transverse shear microscopy(TSM).Three typical nanomechanical systems,MoS_(2) on the amorphous SiO_(2)/Si,graphene on the amorphous SiO_(2)/Si,and MoS_(2) on the crystallized Al_(2)O_(3),have been investigated in detail.This experimental observation reveals that puckering behaviour mainly occurs on the top layer of 2D materials,which is attributed to its direct contact adhesion with the AFM tip.Furthermore,the result of crystallographic orientation imaging of MoS_(2)/SiO_(2)/Si and MoS_(2)/Al_(2)O_(3) indicated that the underlying crystalline substrates almost do not contribute to the puckering effect of 2D materials.Our work directly revealed the top layer dependent puckering properties of 2D material,and demonstrate the general applications of TSM in the bilayer 2D systems.展开更多
Data obtained via airborne position and orientation system (POS) is in WGS 84 global geocentric reference frame, while the national coordinate reference system for topographic mapping in China is generally Gauss-Kru...Data obtained via airborne position and orientation system (POS) is in WGS 84 global geocentric reference frame, while the national coordinate reference system for topographic mapping in China is generally Gauss-Kruger projection coordinate system. Therefore, data obtained via a POS must be transformed to national coordinate system. Owing to the effects of earth curvature and me- ridian deviation, there are some errors in the process of angle transformation from roll, pitch, and heading (φ,θ,ψ) obtained directly via a POS to the attitude angles of images (φ,ω,κ) needed in photogrammetry. On the basis of effect theories of earth curvature and meridian deviation on exterior orientation angular elements of images, a method using a compensation matrix to correct the transformation errors from attitude angles obtained via the POS to exterior orientation angular elements of images is proposed in this paper. Moreover, the rigorous formula of the compensation matrix is deduced. Two sets of actual data obtained via a POS AV 510, which are different in scale and terrain, are selected and used to perform experiments. The empirical results not only indicate that the compensation matrix proposed in this paper is correct and practical but also show that transformation accuracy of exterior orientation angular elements obtained via the POS based on compensation matrix is relevant to the selection of vertical axis (a projection of central meridian) of Gauss-Kruger projection coordinate system; the proper vertical axis should be the Gauss-Kruger projection of the central meridian of projection zone in which the survey area locates. However, the transformation accuracy of exterior orientation angular elements is irrelevant to the choice of origin of coordinate system; it is appropriate that the origin of coordinate system locates at the center point of the survey area. Moreover, transformation accuracy of exterior orientation angular elements achieved based on the compensa- tion matrix deduced in this paper is higher than that obtained via the existing POS processing software.展开更多
The effect of cooling rate on the microstructure and transformation textures of high strength hot-rolled steels was investigated.Heat treated samples subjected to different cooling conditions were characterized by opt...The effect of cooling rate on the microstructure and transformation textures of high strength hot-rolled steels was investigated.Heat treated samples subjected to different cooling conditions were characterized by optical and scanning electron microscopes using orientation imaging microscopy(OIM).The experimental results demonstrate that there is a significant effect of cooling rate on microstructures and textures resulting from phase transformation.Slow cooling rates lead to the appearance of the cube(001)[010],rotated cube(001)[110]/(001)[110],Goss(110)[001]and rotated Goss(110)[110]components.In contrast,textures developed at rapid cooling rates are preferably of Cu(112)[111],Br(110)[112],transformed Cu(113)[110]and transformed Br(332)[113]/(112)[131].These texture changes are attributed to the selective character of the phase transformation.The OIM technique was used to have a better understanding of the formation of phases and their relationship between microstructure and processing conditions.The volume fraction of micro-constituents resulting from phase transformation such as bainite,martensite and different types of ferrite,can be measured satisfactorily by this technique correlating image quality of EBSD patterns to specific phases.展开更多
文摘Lost Horizon tells a story about Shangri-La,a paradise in the Orient.Throughout the construction of the Oriental image in the novel,it can be found that under its representation of being enslaved,driven,marginalized and silenced,it implies a three-dimensional flow mechanism with multiple power-relationships interwoven between Orient and Occident,insiders and outsiders,“civilized”and“uncivilized”,male and female,etc.Driven by this mechanism,the Oriental image is integrated under a single abstract label,which has become a way for the Occident to re-understand,reconstruct and express itself after the war.
文摘Over recent years, Convolutional Neural Networks (CNN) has improved performance on practically every image-based task, including Content-Based Image Retrieval (CBIR). Nevertheless, since features of CNN have altered orientation, training a CBIR system to detect and correct the angle is complex. While it is possible to construct rotation-invariant features by hand, retrieval accuracy will be low because hand engineering only creates low-level features, while deep learning methods build high-level and low-level features simultaneously. This paper presents a novel approach that combines a deep learning orientation angle detection model with the CBIR feature extraction model to correct the rotation angle of any image. This offers a unique construction of a rotation-invariant CBIR system that handles the CNN features that are not rotation invariant. This research also proposes a further study on how a rotation-invariant deep CBIR can recover images from the dataset in real-time. The final results of this system show significant improvement as compared to a default CNN feature extraction model without the OAD.
基金National Natural Science Foundation of China(No.81570462,No.81730049,and No.81801666).
文摘The purpose of this work was to demonstrate the feasibility of neurite orientation dispersion and density imaging(NODDI)in characterizing the brain tissue microstructural changes of middle cerebral artery occlusion(MCAO)in rats at 3T MRI,and to validate NODDI metrics with histology.A multi-shell diffusion MRI protocol was performed on 11 MCAO rats and 10 control rats at different post-operation time points of 0.5,2,6,12,24 and 72 h.NODDI orientation dispersion index(ODI)and intracellular volume fraction(V_(ic))metrics were compared between MCAO group and control group.The evolution of NODDI metrics was characterized and validated by histology.Infarction was consistent with significantly increased ODI and V_(ic)in comparison to control tissues at all time points(P<0.001).Lesion ODI increased gradually from 0.5 to 72 h,while its V_(ic)showed a more complicated and fluctuated evolution.ODI and V_(ic)were significantly different between hyperacute and acute stroke periods(P<0.001).The NODDI metrics were found to be consistent with the histological findings.In conclusion,NODDI can reflect microstructural changes of brain tissues in MCAO rats at 3T MRI and the metrics are consistent with histology.This study helps to prepare NODDI for the diagnosis and management of ischemic stroke in translational research and clinical practice.
基金Projects(61203332,61203208) supported by the National Natural Science Foundation of China
文摘For vision-based mobile robot navigation, images of the same scene may undergo a general affine transformation in the case of significant viewpoint changes. So, a novel method for detecting affine invariant interest points is proposed to obtain the invariant local features, which is coined polynomial local orientation tensor(PLOT). The new detector is based on image local orientation tensor that is constructed from the polynomial expansion of image signal. Firstly, the properties of local orientation tensor of PLOT are analyzed, and a suitable tuning parameter of local orientation tensor is chosen so as to extract invariant features. The initial interest points are detected by local maxima search for the smaller eigenvalues of the orientation tensor. Then, an iterative procedure is used to allow the initial interest points to converge to affine invariant interest points and regions. The performances of this detector are evaluated on the repeatability criteria and recall versus 1-precision graphs, and then are compared with other existing approaches. Experimental results for PLOT show strong performance under affine transformation in the real-world conditions.
基金Project(2010CB731704)supported by the National Basic Research Program of ChinaProject(AWJ-M13-11)supported by State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,ChinaProject(2012M511470)supported by China Postdoctoral Science Foundation
文摘Theα+βtitanium alloy, Ti-6Al-4V, was welded by friction stir welding using a W-Re pin tool, and the defect-free weld was produced with proper welding parameters. Texture of the Ti-6Al-4V friction stir weld was studied by orientation imaging microscopy. The as-received Ti-6Al-4V sheet mill annealed was composed of elongated primary α and transformed β. A typical rolling texture was observed in the base material. The microstructure of the stir zone was significantly different from that of the base material. The stir zone was characterized by the presence of considerable amount of equiaxed dynamically recrystallized grains and a texture around{Ф1=30°,φ=62°,Ф2=30°}was developed during the friction stir welding.
基金supported by research grants from the program for Brain/MINDS Beyond program from the Japan Agency for Medical Research and Development(AMED)under Grant Number JP18dm0307024(to KK)MEXT-Supported Program for the Private University Research Branding Project+1 种基金ImPACT Program of Council for Science,Technology and Innovation(Cabinet Office,Government of Japan)JSPS KAKENHI Grant Number JP16K10327(to KK)
文摘The prevalence of neurodegenerative diseases is increasing as human longevity increases. The objective biomarkers that enable the staging and early diagnosis of neurodegenerative diseases are eagerly anticipated. It has recently become possible to determine pathological changes in the brain without autopsy with the advancement of diffusion magnetic resonance imaging techniques. Diffusion magnetic resonance imaging is a robust tool used to evaluate brain microstructural complexity and integrity, axonal order, density, and myelination via the micron-scale displacement of water molecules diffusing in tissues. Diffusion tensor imaging, a type of diffusion magnetic resonance imaging technique is widely utilized in clinical and research settings;however, it has several limitations. To overcome these limitations, cutting-edge diffusion magnetic resonance imaging techniques, such as diffusional kurtosis imaging, neurite orientation dispersion and density imaging, and free water imaging, have been recently proposed and applied to evaluate the pathology of neurodegenerative diseases. This review focused on the main applications, findings, and future directions of advanced diffusion magnetic resonance imaging techniques in patients with Alzheimer's and Parkinson's diseases, the first and second most common neurodegenerative diseases, respectively.
基金supported in part by the High Magnetic Field Laboratory(NHMFL)and Advanced Magnetic Resonance Imaging and Spectroscopy(AMRIS)under Magnetic Laboratory Visiting Scientist Program Award,No.VSP#327(to RG)。
文摘During the last decades,advances in the understanding of genetic,cellular,and microstructural alterations associated to Huntington's disease(HD)have improved the understanding of this progressive and fatal illness.However,events related to early neuropathological events,neuroinflammation,deterioration of neuronal connectivity and compensatory mechanisms still remain vastly unknown.Ultra-high field diffusion MRI(UHFD-MRI)techniques can contribute to a more comprehensive analysis of the early microstructural changes observed in HD.In addition,it is possible to evaluate if early imaging microstructural parameters might be linked to histological biomarkers.Moreover,qualitative studies analyzing histological complexity in brain areas susceptible to neurodegeneration could provide information on inflammatory events,compensatory increase of neuroconnectivity and mechanisms of brain repair and regeneration.The application of ultra-high field diffusion-MRI technology in animal models,particularly the R6/1 mice(a common preclinical mammalian model of HD),provide the opportunity to analyze alterations in a physiologically intact model of the disease.Although some disparities in volumetric changes across different brain structures between preclinical and clinical models has been documented,further application of different diffusion MRI techniques used in combination like diffusion tensor imaging,and neurite orientation dispersion and density imaging have proved effective in characterizing early parameters associated to alteration in water diffusion exchange within intracellular and extracellular compartments in brain white and grey matter.Thus,the combination of diffusion MRI imaging techniques and more complex neuropathological analysis could accelerate the discovery of new imaging biomarkers and the early diagnosis and neuromonitoring of patients affected with HD.
基金The authors would like to thank NVIDIA Corp.for donating the GPU used in this research through its GPU grant program.The first author Lin Chen would also like to thank the China Scholarship Council(CSC)for financially supporting his PhD study.
文摘In feature based image matching,distinctive features in images are detected and represented by feature descriptors.Matching is then carried out by assessing the similarity of the descriptors of potentially conjugate points.In this paper,we first shortly discuss the general frame-work.Then,we review feature detection as well as the determination of affine shape and orientation of local features,before analyzing feature description in more detail.In the feature description review,the general framework of local feature description is presented first.Then,the review discusses the evolution from hand-crafted feature descriptors,e.g.SIFT(Scale Invariant Feature Transform),to machine learning and deep learning based descriptors.The machine learning models,the training loss and the respective training data of learning-based algorithms are looked at in more detail;subsequently the various advantages and challenges of the different approaches are discussed.Finally,we present and assess some current research directions before concluding the paper.
基金This work was supported by the National Natural Science Foundation of China(NSFC,Grant Nos.21622304,61674045,and 11604063)Ministry of Science and Technology(MOST)of China(Grant No.2016YFA0200700)+5 种基金Strategic Priority Research Program,Key Research Program of Frontier Sciences and Instrument Developing Project of Chinese Academy of Sciences(CASGrant Nos.XDB30000000,QYZDB-SSW-SYS031,and YZ201418)Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science(JSPS)from the Ministry of Education,Culture,Sports,Science,and Technology of Japan(Grant Nos.JP16H06327,JP16H06504,JP17H01061,and JP17H010610)Osaka University’s International Joint Research Promotion Program(Grant Nos.J171013014,J171013007,J181013006,and Ja19990011)Z.H.Cheng was supported by Distinguished Technical Talents Project and Youth Innovation Promotion Association CAS,the Fundamental Research Funds for the Central Universities,and the Research Funds of Renmin University of China(Grant No.18XNLG01)S.Chen appreciate the support from Beijing Natural Science Foundation(Grant No.2192024).
文摘Nanocontact properties of two-dimensional(2D)materials are closely dependent on their unique nanomechanical systems,such as the number of atomic layers and the supporting substrate.Here,we report a direct observation of toplayer-dependent crystallographic orientation imaging of 2D materials with the transverse shear microscopy(TSM).Three typical nanomechanical systems,MoS_(2) on the amorphous SiO_(2)/Si,graphene on the amorphous SiO_(2)/Si,and MoS_(2) on the crystallized Al_(2)O_(3),have been investigated in detail.This experimental observation reveals that puckering behaviour mainly occurs on the top layer of 2D materials,which is attributed to its direct contact adhesion with the AFM tip.Furthermore,the result of crystallographic orientation imaging of MoS_(2)/SiO_(2)/Si and MoS_(2)/Al_(2)O_(3) indicated that the underlying crystalline substrates almost do not contribute to the puckering effect of 2D materials.Our work directly revealed the top layer dependent puckering properties of 2D material,and demonstrate the general applications of TSM in the bilayer 2D systems.
基金Supported by the National Natural Science Foundation of China (No. 40771176, No. 40721001)supported by the Institute of Remote Sensing Applications in Chinese Academy of Sciences, Zhongfei General Aviation Company, Liaoning Jingwei Surveying & Mapping Technology INC, Siwei Aviation Remote Sensing Co. Ltd., and others
文摘Data obtained via airborne position and orientation system (POS) is in WGS 84 global geocentric reference frame, while the national coordinate reference system for topographic mapping in China is generally Gauss-Kruger projection coordinate system. Therefore, data obtained via a POS must be transformed to national coordinate system. Owing to the effects of earth curvature and me- ridian deviation, there are some errors in the process of angle transformation from roll, pitch, and heading (φ,θ,ψ) obtained directly via a POS to the attitude angles of images (φ,ω,κ) needed in photogrammetry. On the basis of effect theories of earth curvature and meridian deviation on exterior orientation angular elements of images, a method using a compensation matrix to correct the transformation errors from attitude angles obtained via the POS to exterior orientation angular elements of images is proposed in this paper. Moreover, the rigorous formula of the compensation matrix is deduced. Two sets of actual data obtained via a POS AV 510, which are different in scale and terrain, are selected and used to perform experiments. The empirical results not only indicate that the compensation matrix proposed in this paper is correct and practical but also show that transformation accuracy of exterior orientation angular elements obtained via the POS based on compensation matrix is relevant to the selection of vertical axis (a projection of central meridian) of Gauss-Kruger projection coordinate system; the proper vertical axis should be the Gauss-Kruger projection of the central meridian of projection zone in which the survey area locates. However, the transformation accuracy of exterior orientation angular elements is irrelevant to the choice of origin of coordinate system; it is appropriate that the origin of coordinate system locates at the center point of the survey area. Moreover, transformation accuracy of exterior orientation angular elements achieved based on the compensa- tion matrix deduced in this paper is higher than that obtained via the existing POS processing software.
文摘The effect of cooling rate on the microstructure and transformation textures of high strength hot-rolled steels was investigated.Heat treated samples subjected to different cooling conditions were characterized by optical and scanning electron microscopes using orientation imaging microscopy(OIM).The experimental results demonstrate that there is a significant effect of cooling rate on microstructures and textures resulting from phase transformation.Slow cooling rates lead to the appearance of the cube(001)[010],rotated cube(001)[110]/(001)[110],Goss(110)[001]and rotated Goss(110)[110]components.In contrast,textures developed at rapid cooling rates are preferably of Cu(112)[111],Br(110)[112],transformed Cu(113)[110]and transformed Br(332)[113]/(112)[131].These texture changes are attributed to the selective character of the phase transformation.The OIM technique was used to have a better understanding of the formation of phases and their relationship between microstructure and processing conditions.The volume fraction of micro-constituents resulting from phase transformation such as bainite,martensite and different types of ferrite,can be measured satisfactorily by this technique correlating image quality of EBSD patterns to specific phases.