The ductile-to-brittle transition temperature(DBTT)of high strength steels can be optimized by tailoring microstructure and crystallographic orientation characteristics,where the start cooling temperature plays a key ...The ductile-to-brittle transition temperature(DBTT)of high strength steels can be optimized by tailoring microstructure and crystallographic orientation characteristics,where the start cooling temperature plays a key role.In this work,X70 steels with different start cooling temperatures were prepared through thermo-mechanical control process.The quasi-polygonal ferrite(QF),granular bainite(GB),bainitic ferrite(BF)and martensite-austenite constituents were formed at the start cooling temperatures of 780℃(C1),740℃(C2)and 700℃(C3).As start cooling temperature decreased,the amount of GB decreased,the microstructure of QF and BF increased.Microstructure characteristics of the three samples,such as high-angle grain boundaries(HAGBs),MA constituents and crystallographic orientation,also varied with the start cooling temperatures.C2 sample had the lowest DBTT value(−86℃)for its highest fraction of HAGBs,highest content of<110>oriented grains and lowest content of<001>oriented grains parallel to TD.The high density of{332}<113>and low density of rotated cube{001}<110>textures also contributed to the best impact toughness of C2 sample.In addition,a modified model was used in this paper to quantitatively predict the approximate DBTT value of steels.展开更多
In this research, effect of varying spatial orientations on the build time requirements for fused deposition modelling process is studied. Constructive solid geometry cylindrical primitive is taken as work piece and m...In this research, effect of varying spatial orientations on the build time requirements for fused deposition modelling process is studied. Constructive solid geometry cylindrical primitive is taken as work piece and modeling is accomplished for it. Response surface methodology is used to design the experiments and obtain statistical models for build time requirements corresponding to different orientations of the given primitive in modeller build volume. Contour width, air gap, slice height, raster width, raster angle and angle of orientation are treated as process parameters. Percentage contribution of individual process parameter is found to change for build time corresponding to different spatial orientations. Also, the average of build time requirement changes with spatial orientation. This paper attempts to clearly discuss and describe the observations with an aim to develop a clear understanding of effect of spatial variations on the build time for Fused Deposition Modelling process. This work is an integral part of process layout optimization and these results can effectively aid designers specially while tackling nesting issues.展开更多
In this paper,the HRTEM lattice fringe micrograph of Caocun No.2 coal was extracted by ArcGIS,the length and orientation of the fringes were calculated,and the rose diagram for the lattice fringe micrograph was drawn ...In this paper,the HRTEM lattice fringe micrograph of Caocun No.2 coal was extracted by ArcGIS,the length and orientation of the fringes were calculated,and the rose diagram for the lattice fringe micrograph was drawn by Matlab.By controlling the segmentation points of each lattice fringe,the coordinates of the segmentation points were processed by a self-programmed Python program,and then a series of curvature characterizations including segmentation angle,cumulative angle and tortuosity were performed for lattice fringes with different lengths.The results show that Caocun No.2 coal is mainly composed of short naphthalene fringes.Lattice fringes with the length ranging from 0.3 nm to 1.14 nm account for more than 90%of the total number of fringes,and the number of polynuclear aromatic rings was 2-4.The direction of lattice fringes is concentrated between 110°and 120°,which indicates well structural orientation of lattice fringes.The number of segment angles ranging from 0°to 20°account for about half of the total,which reflects the structural orientation further.For fringes with the length ranging from 0.3 nm to 1.14 nm,the cumulative angles are mainly concentrated at 4°to 160°.Fringes with the tortuosity in the range of 1.0-1.1 are more than 92%of the total number of fringes.In addition,short fringes have large curvature,which shows significant effects on the placement and frequency of non-six-membered rings and lattice imperfection in the aromatic structure.展开更多
Along with the rapid advance of industrialization and urbanization process, fostering new agricultural business entities become inevitable for agricultural transformation and the construction of agricultural moderniza...Along with the rapid advance of industrialization and urbanization process, fostering new agricultural business entities become inevitable for agricultural transformation and the construction of agricultural modernization in China. The status of the new agricultural business entities determines the level of modern agricultural development. In recent years, new agricultural business entities have grew rapidly. However, there are still many problems including the difficulties in financing loans, inadequate agricultural insurance system, bad implementation of agricultural subsidies, jagged agricultural talents and so on. In order to foster new agricultural business entities, countermeasures should be carried out to ensure financial support, perfect the agricultural insurance, strengthen the level of agricultural subsidies, strive to develop the degree of specialization agricultural operators and so on.展开更多
Singular point(SP)extraction is a key component in automatic fingerprint identification system(AFIS).A new method was proposed for fingerprint singular points extraction,based on orientation tensor field and Laurent s...Singular point(SP)extraction is a key component in automatic fingerprint identification system(AFIS).A new method was proposed for fingerprint singular points extraction,based on orientation tensor field and Laurent series.First,fingerprint orientation flow field was obtained,using the gradient of fingerprint image.With these gradients,fingerprint orientation tensor field was calculated.Then,candidate SPs were detected by the cross-correlation energy in multi-scale Gaussian space.The energy was calculated between fingerprint orientation tensor field and Laurent polynomial model.As a global descriptor,the Laurent polynomial coefficients were allowed for rotational invariance.Furthermore,a support vector machine(SVM)classifier was trained to remove spurious SPs,using cross-correlation coefficient as a feature vector.Finally,experiments were performed on Singular Point Detection Competition 2010(SPD2010)database.Compared to the winner algorithm of SPD2010 which has best accuracy of 31.90%,the accuracy of proposed algorithm is 45.34%.The results show that the proposed method outperforms the state-of-the-art detection algorithms by large margin,and the detection is invariant to rotational transformations.展开更多
High density lanthanum hexaboride(LaB_(6))polycrystalline with(100)preferred orientation was prepared by spark plasma sintering(SPS)using LaB_(6) nanocubes as raw materials in this work.Microstructure and thermionic e...High density lanthanum hexaboride(LaB_(6))polycrystalline with(100)preferred orientation was prepared by spark plasma sintering(SPS)using LaB_(6) nanocubes as raw materials in this work.Microstructure and thermionic electron emission property of LaB_(6) polycrystalline were investigated detailedly.The results show that the LaB_(6) polycrystalline had a relative density of 95.8%,and there was a(100)preferred orientation on its surface normal to SPS pressing direction.The work function of LaB_(6) polycrystalline normal surface was only 2.73 eV,which was almost close to the theoretical work function of LaB_(6)(100)single crystal surface.The reasons for preferential orientation of LaB_(6) polycrystalline were analyzed.展开更多
Underground mines require complex construction activities including the shaft, levels, raises, winzes and ore passes. In an underground mine based on stoping method, orebody part(s) maximizing profit should be determi...Underground mines require complex construction activities including the shaft, levels, raises, winzes and ore passes. In an underground mine based on stoping method, orebody part(s) maximizing profit should be determined. This process is called stope layout optimization (SLO) and implemented under site-specific geotechnical, operational and economic constraints. For practical purpose, the design obtained by SLO shows consecutive stopes in one path, which assists in defining the mining direction of these stopes. However, this direction may not accommodate the spatial distribution of the ore grade: if the orebody orientation and mining direction differ, the value of the mining operation may decrease. This paper proposes an approach whereby paths in the SLO are defined as decision variables to avoid the cost of mining in the wrong direction. Furthermore, in the genetic-based formulation, which accounts for orebody uncertainty, a robust cluster average design process is proposed to improve SLO’s performance regarding metal content. A case study in narrow gold vein deposit shows that the profit of an underground mining operation could be underestimated by 25%-48% if the algorithm ignores stope layout orientation.展开更多
The scattering-model-based(SMB)speckle filtering for polarimetric SAR(Pol SAR)data is reasonably effective in preserving dominant scattering mechanisms.However,the efficiency strongly depends on the accuracies of both...The scattering-model-based(SMB)speckle filtering for polarimetric SAR(Pol SAR)data is reasonably effective in preserving dominant scattering mechanisms.However,the efficiency strongly depends on the accuracies of both the decomposition and classification of the scattering properties.In addition,a relatively weak speckle reduction particularly in distributed media was reported in the related literatures.In this work,an improved SMB filtering strategy is proposed considering the aforementioned deficiencies.First,the orientation angle compensation is incorporated into the SMB filtering process to remedy the overestimation of the volume scattering contribution in the Freeman-Durden decomposition.In addition,an algorithm to select the homogenous pixels is developed based on the spatial majority rule for adaptive speckle reduction.We demonstrate the superiority of the proposed methods in terms of scattering property preservation and speckle noise reduction using L-band Pol SAR data sets of San Francisco that were acquired by the NASA/JPL airborne SAR(AIRSAR)system.展开更多
A novel multi-view 3D face registration method based on principal axis analysis and labeled regions orientation called local orientation registration is proposed.The pre-registration is achieved by transforming the mu...A novel multi-view 3D face registration method based on principal axis analysis and labeled regions orientation called local orientation registration is proposed.The pre-registration is achieved by transforming the multi-pose models to the standard frontal model＇s reference frame using the principal axis analysis algorithm.Some significant feature regions, such as inner and outer canthus, nose tip vertices, are then located by using geometrical distribution characteristics.These regions are subsequently employed to compute the conversion parameters using the improved iterative closest point algorithm, and the optimal parameters are applied to complete the final registration.Experimental results implemented on the proper database demonstrate that the proposed method significantly outperforms others by achieving 1.249 and 1.910 mean root-mean-square measure with slight and large view variation models, respectively.展开更多
Comprehensive tests on Hangzhou intact soft clay were performed, which were used to obtain the soils' critical response to undrained dynamic stress paths under different combinations of principal stress orientatio...Comprehensive tests on Hangzhou intact soft clay were performed, which were used to obtain the soils' critical response to undrained dynamic stress paths under different combinations of principal stress orientation. The different combinations included cyclic principal stress rotation (CPSR for short), cyclic shear with abrupt change of principal stress orientation (CAPSO for short) and cyclic shear with fixed principal stress orientation (CFPSO for short). On one side, under all these stress paths, samples have obvious strain inflection points and shear bands, and the excess pore water pressure is far from the level of initial effective confining pressure at failure. Stress paths of major principal stress orientation (α) alternating from negative and positive have quite different influence on soil's properties with those in which α is kept negative or positive. On the other side, due to the soil's strongly initial anisotropy, samples under double-amplitudes CPSR and CAPSO (or single-amplitude CPSR and CFPSO) have similar properties on dynamic shear strength and pore water pressure development tendency when α is kept within ±45°, while have quite different properties when α oversteps ±45°.展开更多
The basic scheme of the orientation detection system using L-shape reticle is introduced. The dimension of the patterns on the reticle of the system in practical applications is designed and an analysis of the princip...The basic scheme of the orientation detection system using L-shape reticle is introduced. The dimension of the patterns on the reticle of the system in practical applications is designed and an analysis of the principle of abstracting the orientation information of the target and the effects and formation method of self-adapting tracking gate is presented. The research result shows that the orientation detection system using L-shape reticle has a good effect on space-filtering, the signals that the orientation detection system sends out are easy to be processed by computer, its self-adapting tracking gate has a strong anti-interference ability, and the whole system＇s searching and tracking performances are quite high.展开更多
Collective cell groups are organized to form specific patterns that play an important role in various physiological and pathological processes,such as tissue morphogenesis,wound healing,and cancer invasion.Compared to...Collective cell groups are organized to form specific patterns that play an important role in various physiological and pathological processes,such as tissue morphogenesis,wound healing,and cancer invasion.Compared to the behaviors of single cells that have been studied intensively from many aspects(cell migration,adhesion,polarization,proliferation,etc.)and at various length scales(molecular,subcellular,and cellular),the behaviors of multiple cells are less well understood,particularly from a quantitative perspective.In this talk,we present our recent studies of collective polarization and orientation of multiple cells through both experimental measurement and theoretical modeling,including cell behavior on/in 2D and 3D substrate/tissue.We find that collective cell behavior,including polarization,alignment,and migration,is closely related to local stress states in cell layers or tissue,which demonstrates the crucial role of mechanical forces in living organisms.Specifically,cells demonstrate preferential polarization and alignment along the maximum principal stress in the cell layer,and the cell aspect ratio increases with in-plane maximum shear stress,suggesting that the maximum shear stress is the underlying driving force of cell polarization and orientation.This theory of stress-driven cell behaviors of polarization and orientation provides a new perspective for understanding cell behaviors in living organisms and a guideline for tissue engineering in potential biomedical applications.Strikingly,we note that with regard to the polarization and alignment of collective cells,a typical feature of cell morphology is that the cells generally align along the edge of the pattern,which was called edge effect or boundary effect by assuming that the edge plays a role in cell alignment due to a phenomenon of chemistry.However,the edge effect is an obscure explanation.Here we showed that the edge effect could be explained by the theory of stress-driven cell behavior,i.e.,inplane stress-driven cell polarization and alignment.That is,the cell layer has a stress-free boundary condition at the edge,and thus the direction of the maximum principal stress should be precisely along the edge.According to the theory of stress-driven cell polarity,the cells then preferentially align with the edge of the cell layer,independently of the geometry of the pattern.Once there is a force-free condition at the edge or the boundary,the cells align along the edge of the pattern.Otherwise,the cell may not align with the edge;for example,the cells preferentially align in the radial direction of the wound because of the presence of the contractile force by the actin ring at the wound edge,which is in contradiction with the so-called edge effect but consistent with our theory of stress-driven cell polarity.展开更多
In cross-cultural communication(CC),due to the different cultural backgrounds and values,there are great differences between Chinese and Western thinking patterns,which often lead to cultural conflicts.Cultural differ...In cross-cultural communication(CC),due to the different cultural backgrounds and values,there are great differences between Chinese and Western thinking patterns,which often lead to cultural conflicts.Cultural differences cover a wide range,and this paper analyzes the great influence of cultural differences on CC from the perspectives of thinking patterns and value orientation in daily life in China and the West,and intends to find out the reasons behind and come up with solutions.展开更多
The influence of crystallographic orientation on the void growth in FCC crystals was numerically simulated with 3D crystal plasticity finite element by using a 3D unit cell including a spherical void, and the rate-dep...The influence of crystallographic orientation on the void growth in FCC crystals was numerically simulated with 3D crystal plasticity finite element by using a 3D unit cell including a spherical void, and the rate-dependent crystal plasticity theory was implemented as a user material subroutine. The results of the simulations show that crystallographic orientation has significant influence on the growth behavior of the void. Different active slip systems of the regions around the void cause the discontinuity in lattice rotation around the void, and the corner-like region is formed. In the case of the void located at grain boundary, large heterogeneous deformation occurs between the two grains, and the equivalent plastic deformation along grain boundary near the void in the case of θ=45^o （θ is the angle between grain boundary direction and X-axis） is larger than the others. Large difference of orientation factor of the two grains leads to large equivalent plastic deformation along grain boundary, and the unit cell is more likely to fail by intergranular fracture.展开更多
In the study of oriented bounding boxes(OBB)object detection in high-resolution remote sensing images,the problem of missed and wrong detection of small targets occurs because the targets are too small and have differ...In the study of oriented bounding boxes(OBB)object detection in high-resolution remote sensing images,the problem of missed and wrong detection of small targets occurs because the targets are too small and have different orientations.Existing OBB object detection for remote sensing images,although making good progress,mainly focuses on directional modeling,while less consideration is given to the size of the object as well as the problem of missed detection.In this study,a method based on improved YOLOv8 was proposed for detecting oriented objects in remote sensing images,which can improve the detection precision of oriented objects in remote sensing images.Firstly,the ResCBAMG module was innovatively designed,which could better extract channel and spatial correlation information.Secondly,the innovative top-down feature fusion layer network structure was proposed in conjunction with the Efficient Channel Attention(ECA)attention module,which helped to capture inter-local cross-channel interaction information appropriately.Finally,we introduced an innovative ResCBAMG module between the different C2f modules and detection heads of the bottom-up feature fusion layer.This innovative structure helped the model to better focus on the target area.The precision and robustness of oriented target detection were also improved.Experimental results on the DOTA-v1.5 dataset showed that the detection Precision,mAP@0.5,and mAP@0.5:0.95 metrics of the improved model are better compared to the original model.This improvement is effective in detecting small targets and complex scenes.展开更多
Background:Cell division is one of the key roles in the cell development,cell differentiation,embryogenesis and recovery of tissues.Independent studies have shown that spindle alignment during not only asymmetric but ...Background:Cell division is one of the key roles in the cell development,cell differentiation,embryogenesis and recovery of tissues.Independent studies have shown that spindle alignment during not only asymmetric but also symmetric cell divisions is essential展开更多
Virtual testing of fabric armor provides an efficient and inexpensive means of systematically studying the influence of various architectural and material parameters on the ballistic impact behavior of woven fabrics, ...Virtual testing of fabric armor provides an efficient and inexpensive means of systematically studying the influence of various architectural and material parameters on the ballistic impact behavior of woven fabrics, before actual laboratory prototypes are woven and destructively tested. In this finite element study, the combined effects of individual ply orientations and material properties on the impact performance of multi-layered, non-stitched woven aramid fabrics are studied using 2-and 4-sided clamping configurations. Individual ply orientations of 0°, ±15°, ±30°, and ±45° are considered along with three levels of inter-yarn friction coefficient. Functionally graded fabric targets are also considered wherein the yarn stiffness progressively increases or decreases through the target thickness while keeping the yarn strain energy density constant and with all other material and architectural parameters unchanged for consistency. For each target configuration, one non-penetrating and one penetrating impact velocity is chosen. The impact performance is evaluated by the time taken to arrest the projectile and the backface deformation for the non-penetrating impacts, and by the residual velocity for the penetrating impact tests. All deterministic impact simulations are performed using LS-DYNA. 2-sided clamped targets and lower inter-yarn frictional levels generally resulted in better impact performance.The functionally graded targets generally showed either similar or inferior impact performance than the baseline fabric target configurations for the non-penetrating shots. Some performance improvements were observed for the penetrating shots when the yarn stiffness was progressively decreased through the layers in a direction away from the strike face, with additional performance enhancements achieved by simultaneously reducing the inter-yarn friction.展开更多
基金Project(2018XK2301) supported by the Change-Zhu-Tan National Independent Innavation Demonstration Zone Special Program,China。
文摘The ductile-to-brittle transition temperature(DBTT)of high strength steels can be optimized by tailoring microstructure and crystallographic orientation characteristics,where the start cooling temperature plays a key role.In this work,X70 steels with different start cooling temperatures were prepared through thermo-mechanical control process.The quasi-polygonal ferrite(QF),granular bainite(GB),bainitic ferrite(BF)and martensite-austenite constituents were formed at the start cooling temperatures of 780℃(C1),740℃(C2)and 700℃(C3).As start cooling temperature decreased,the amount of GB decreased,the microstructure of QF and BF increased.Microstructure characteristics of the three samples,such as high-angle grain boundaries(HAGBs),MA constituents and crystallographic orientation,also varied with the start cooling temperatures.C2 sample had the lowest DBTT value(−86℃)for its highest fraction of HAGBs,highest content of<110>oriented grains and lowest content of<001>oriented grains parallel to TD.The high density of{332}<113>and low density of rotated cube{001}<110>textures also contributed to the best impact toughness of C2 sample.In addition,a modified model was used in this paper to quantitatively predict the approximate DBTT value of steels.
文摘In this research, effect of varying spatial orientations on the build time requirements for fused deposition modelling process is studied. Constructive solid geometry cylindrical primitive is taken as work piece and modeling is accomplished for it. Response surface methodology is used to design the experiments and obtain statistical models for build time requirements corresponding to different orientations of the given primitive in modeller build volume. Contour width, air gap, slice height, raster width, raster angle and angle of orientation are treated as process parameters. Percentage contribution of individual process parameter is found to change for build time corresponding to different spatial orientations. Also, the average of build time requirement changes with spatial orientation. This paper attempts to clearly discuss and describe the observations with an aim to develop a clear understanding of effect of spatial variations on the build time for Fused Deposition Modelling process. This work is an integral part of process layout optimization and these results can effectively aid designers specially while tackling nesting issues.
基金Supported by the National Natural Science Foundation of China(41602177,41802191,41702175)
文摘In this paper,the HRTEM lattice fringe micrograph of Caocun No.2 coal was extracted by ArcGIS,the length and orientation of the fringes were calculated,and the rose diagram for the lattice fringe micrograph was drawn by Matlab.By controlling the segmentation points of each lattice fringe,the coordinates of the segmentation points were processed by a self-programmed Python program,and then a series of curvature characterizations including segmentation angle,cumulative angle and tortuosity were performed for lattice fringes with different lengths.The results show that Caocun No.2 coal is mainly composed of short naphthalene fringes.Lattice fringes with the length ranging from 0.3 nm to 1.14 nm account for more than 90%of the total number of fringes,and the number of polynuclear aromatic rings was 2-4.The direction of lattice fringes is concentrated between 110°and 120°,which indicates well structural orientation of lattice fringes.The number of segment angles ranging from 0°to 20°account for about half of the total,which reflects the structural orientation further.For fringes with the length ranging from 0.3 nm to 1.14 nm,the cumulative angles are mainly concentrated at 4°to 160°.Fringes with the tortuosity in the range of 1.0-1.1 are more than 92%of the total number of fringes.In addition,short fringes have large curvature,which shows significant effects on the placement and frequency of non-six-membered rings and lattice imperfection in the aromatic structure.
基金Supported by the National Social Science Fund(13CJY079)the National Natural Science Fund(71303039)
文摘Along with the rapid advance of industrialization and urbanization process, fostering new agricultural business entities become inevitable for agricultural transformation and the construction of agricultural modernization in China. The status of the new agricultural business entities determines the level of modern agricultural development. In recent years, new agricultural business entities have grew rapidly. However, there are still many problems including the difficulties in financing loans, inadequate agricultural insurance system, bad implementation of agricultural subsidies, jagged agricultural talents and so on. In order to foster new agricultural business entities, countermeasures should be carried out to ensure financial support, perfect the agricultural insurance, strengthen the level of agricultural subsidies, strive to develop the degree of specialization agricultural operators and so on.
基金Project(11JJ3080)supported by Natural Science Foundation of Hunan Province,ChinaProject(11CY012)supported by Cultivation in Hunan Colleges and Universities,ChinaProject(ET51007)supported by Youth Talent in Hunan University,China
文摘Singular point(SP)extraction is a key component in automatic fingerprint identification system(AFIS).A new method was proposed for fingerprint singular points extraction,based on orientation tensor field and Laurent series.First,fingerprint orientation flow field was obtained,using the gradient of fingerprint image.With these gradients,fingerprint orientation tensor field was calculated.Then,candidate SPs were detected by the cross-correlation energy in multi-scale Gaussian space.The energy was calculated between fingerprint orientation tensor field and Laurent polynomial model.As a global descriptor,the Laurent polynomial coefficients were allowed for rotational invariance.Furthermore,a support vector machine(SVM)classifier was trained to remove spurious SPs,using cross-correlation coefficient as a feature vector.Finally,experiments were performed on Singular Point Detection Competition 2010(SPD2010)database.Compared to the winner algorithm of SPD2010 which has best accuracy of 31.90%,the accuracy of proposed algorithm is 45.34%.The results show that the proposed method outperforms the state-of-the-art detection algorithms by large margin,and the detection is invariant to rotational transformations.
基金Project(51902342)supported by the National Natural Science Foundation of China。
文摘High density lanthanum hexaboride(LaB_(6))polycrystalline with(100)preferred orientation was prepared by spark plasma sintering(SPS)using LaB_(6) nanocubes as raw materials in this work.Microstructure and thermionic electron emission property of LaB_(6) polycrystalline were investigated detailedly.The results show that the LaB_(6) polycrystalline had a relative density of 95.8%,and there was a(100)preferred orientation on its surface normal to SPS pressing direction.The work function of LaB_(6) polycrystalline normal surface was only 2.73 eV,which was almost close to the theoretical work function of LaB_(6)(100)single crystal surface.The reasons for preferential orientation of LaB_(6) polycrystalline were analyzed.
基金Project(488262-15)supported by the Natural Sciences and Engineering Research Council of Canada
文摘Underground mines require complex construction activities including the shaft, levels, raises, winzes and ore passes. In an underground mine based on stoping method, orebody part(s) maximizing profit should be determined. This process is called stope layout optimization (SLO) and implemented under site-specific geotechnical, operational and economic constraints. For practical purpose, the design obtained by SLO shows consecutive stopes in one path, which assists in defining the mining direction of these stopes. However, this direction may not accommodate the spatial distribution of the ore grade: if the orebody orientation and mining direction differ, the value of the mining operation may decrease. This paper proposes an approach whereby paths in the SLO are defined as decision variables to avoid the cost of mining in the wrong direction. Furthermore, in the genetic-based formulation, which accounts for orebody uncertainty, a robust cluster average design process is proposed to improve SLO’s performance regarding metal content. A case study in narrow gold vein deposit shows that the profit of an underground mining operation could be underestimated by 25%-48% if the algorithm ignores stope layout orientation.
基金Project(2012CB957702) supported by the National Basic Research Program of ChinaProjects(41590854,41431070,41274024,41321063) supported by the National Natural Science Foundation of ChinaProject(Y205771077) supported by the Hundred Talents Program of the Chinese Academy of Sciences
文摘The scattering-model-based(SMB)speckle filtering for polarimetric SAR(Pol SAR)data is reasonably effective in preserving dominant scattering mechanisms.However,the efficiency strongly depends on the accuracies of both the decomposition and classification of the scattering properties.In addition,a relatively weak speckle reduction particularly in distributed media was reported in the related literatures.In this work,an improved SMB filtering strategy is proposed considering the aforementioned deficiencies.First,the orientation angle compensation is incorporated into the SMB filtering process to remedy the overestimation of the volume scattering contribution in the Freeman-Durden decomposition.In addition,an algorithm to select the homogenous pixels is developed based on the spatial majority rule for adaptive speckle reduction.We demonstrate the superiority of the proposed methods in terms of scattering property preservation and speckle noise reduction using L-band Pol SAR data sets of San Francisco that were acquired by the NASA/JPL airborne SAR(AIRSAR)system.
基金supported by the New Century Excellent Talents of China (NCET-05-0866)
文摘A novel multi-view 3D face registration method based on principal axis analysis and labeled regions orientation called local orientation registration is proposed.The pre-registration is achieved by transforming the multi-pose models to the standard frontal model＇s reference frame using the principal axis analysis algorithm.Some significant feature regions, such as inner and outer canthus, nose tip vertices, are then located by using geometrical distribution characteristics.These regions are subsequently employed to compute the conversion parameters using the improved iterative closest point algorithm, and the optimal parameters are applied to complete the final registration.Experimental results implemented on the proper database demonstrate that the proposed method significantly outperforms others by achieving 1.249 and 1.910 mean root-mean-square measure with slight and large view variation models, respectively.
基金Projects(50308025 50639010) supported by the National Natural Science Foundation of China
文摘Comprehensive tests on Hangzhou intact soft clay were performed, which were used to obtain the soils' critical response to undrained dynamic stress paths under different combinations of principal stress orientation. The different combinations included cyclic principal stress rotation (CPSR for short), cyclic shear with abrupt change of principal stress orientation (CAPSO for short) and cyclic shear with fixed principal stress orientation (CFPSO for short). On one side, under all these stress paths, samples have obvious strain inflection points and shear bands, and the excess pore water pressure is far from the level of initial effective confining pressure at failure. Stress paths of major principal stress orientation (α) alternating from negative and positive have quite different influence on soil's properties with those in which α is kept negative or positive. On the other side, due to the soil's strongly initial anisotropy, samples under double-amplitudes CPSR and CAPSO (or single-amplitude CPSR and CFPSO) have similar properties on dynamic shear strength and pore water pressure development tendency when α is kept within ±45°, while have quite different properties when α oversteps ±45°.
文摘The basic scheme of the orientation detection system using L-shape reticle is introduced. The dimension of the patterns on the reticle of the system in practical applications is designed and an analysis of the principle of abstracting the orientation information of the target and the effects and formation method of self-adapting tracking gate is presented. The research result shows that the orientation detection system using L-shape reticle has a good effect on space-filtering, the signals that the orientation detection system sends out are easy to be processed by computer, its self-adapting tracking gate has a strong anti-interference ability, and the whole system＇s searching and tracking performances are quite high.
基金supported by the National Natural Science Foundation of China ( 11772055,11532009)
文摘Collective cell groups are organized to form specific patterns that play an important role in various physiological and pathological processes,such as tissue morphogenesis,wound healing,and cancer invasion.Compared to the behaviors of single cells that have been studied intensively from many aspects(cell migration,adhesion,polarization,proliferation,etc.)and at various length scales(molecular,subcellular,and cellular),the behaviors of multiple cells are less well understood,particularly from a quantitative perspective.In this talk,we present our recent studies of collective polarization and orientation of multiple cells through both experimental measurement and theoretical modeling,including cell behavior on/in 2D and 3D substrate/tissue.We find that collective cell behavior,including polarization,alignment,and migration,is closely related to local stress states in cell layers or tissue,which demonstrates the crucial role of mechanical forces in living organisms.Specifically,cells demonstrate preferential polarization and alignment along the maximum principal stress in the cell layer,and the cell aspect ratio increases with in-plane maximum shear stress,suggesting that the maximum shear stress is the underlying driving force of cell polarization and orientation.This theory of stress-driven cell behaviors of polarization and orientation provides a new perspective for understanding cell behaviors in living organisms and a guideline for tissue engineering in potential biomedical applications.Strikingly,we note that with regard to the polarization and alignment of collective cells,a typical feature of cell morphology is that the cells generally align along the edge of the pattern,which was called edge effect or boundary effect by assuming that the edge plays a role in cell alignment due to a phenomenon of chemistry.However,the edge effect is an obscure explanation.Here we showed that the edge effect could be explained by the theory of stress-driven cell behavior,i.e.,inplane stress-driven cell polarization and alignment.That is,the cell layer has a stress-free boundary condition at the edge,and thus the direction of the maximum principal stress should be precisely along the edge.According to the theory of stress-driven cell polarity,the cells then preferentially align with the edge of the cell layer,independently of the geometry of the pattern.Once there is a force-free condition at the edge or the boundary,the cells align along the edge of the pattern.Otherwise,the cell may not align with the edge;for example,the cells preferentially align in the radial direction of the wound because of the presence of the contractile force by the actin ring at the wound edge,which is in contradiction with the so-called edge effect but consistent with our theory of stress-driven cell polarity.
基金The research is supported by the foundation of Chengdu University of Technology for Key Teachers(10912-JXGG2020-00539)It is also a researching finding of the Project of Sichuan Foreign Language Literature Research Center“A Research of Sichuan Opera Translation and Overseas Circulation in Cross-cultural Communication”(SCYC2020-03).
文摘In cross-cultural communication(CC),due to the different cultural backgrounds and values,there are great differences between Chinese and Western thinking patterns,which often lead to cultural conflicts.Cultural differences cover a wide range,and this paper analyzes the great influence of cultural differences on CC from the perspectives of thinking patterns and value orientation in daily life in China and the West,and intends to find out the reasons behind and come up with solutions.
基金Project(2005CB623706) supported by the Major State Basic Research Development Program of China
文摘The influence of crystallographic orientation on the void growth in FCC crystals was numerically simulated with 3D crystal plasticity finite element by using a 3D unit cell including a spherical void, and the rate-dependent crystal plasticity theory was implemented as a user material subroutine. The results of the simulations show that crystallographic orientation has significant influence on the growth behavior of the void. Different active slip systems of the regions around the void cause the discontinuity in lattice rotation around the void, and the corner-like region is formed. In the case of the void located at grain boundary, large heterogeneous deformation occurs between the two grains, and the equivalent plastic deformation along grain boundary near the void in the case of θ=45^o （θ is the angle between grain boundary direction and X-axis） is larger than the others. Large difference of orientation factor of the two grains leads to large equivalent plastic deformation along grain boundary, and the unit cell is more likely to fail by intergranular fracture.
文摘In the study of oriented bounding boxes(OBB)object detection in high-resolution remote sensing images,the problem of missed and wrong detection of small targets occurs because the targets are too small and have different orientations.Existing OBB object detection for remote sensing images,although making good progress,mainly focuses on directional modeling,while less consideration is given to the size of the object as well as the problem of missed detection.In this study,a method based on improved YOLOv8 was proposed for detecting oriented objects in remote sensing images,which can improve the detection precision of oriented objects in remote sensing images.Firstly,the ResCBAMG module was innovatively designed,which could better extract channel and spatial correlation information.Secondly,the innovative top-down feature fusion layer network structure was proposed in conjunction with the Efficient Channel Attention(ECA)attention module,which helped to capture inter-local cross-channel interaction information appropriately.Finally,we introduced an innovative ResCBAMG module between the different C2f modules and detection heads of the bottom-up feature fusion layer.This innovative structure helped the model to better focus on the target area.The precision and robustness of oriented target detection were also improved.Experimental results on the DOTA-v1.5 dataset showed that the detection Precision,mAP@0.5,and mAP@0.5:0.95 metrics of the improved model are better compared to the original model.This improvement is effective in detecting small targets and complex scenes.
文摘Background:Cell division is one of the key roles in the cell development,cell differentiation,embryogenesis and recovery of tissues.Independent studies have shown that spindle alignment during not only asymmetric but also symmetric cell divisions is essential
基金support from the M.C.Gill Composites Center at the University of Southern California(USC)supported by the USC Center for High-Performance Computing(hpcc.usc.edu)
文摘Virtual testing of fabric armor provides an efficient and inexpensive means of systematically studying the influence of various architectural and material parameters on the ballistic impact behavior of woven fabrics, before actual laboratory prototypes are woven and destructively tested. In this finite element study, the combined effects of individual ply orientations and material properties on the impact performance of multi-layered, non-stitched woven aramid fabrics are studied using 2-and 4-sided clamping configurations. Individual ply orientations of 0°, ±15°, ±30°, and ±45° are considered along with three levels of inter-yarn friction coefficient. Functionally graded fabric targets are also considered wherein the yarn stiffness progressively increases or decreases through the target thickness while keeping the yarn strain energy density constant and with all other material and architectural parameters unchanged for consistency. For each target configuration, one non-penetrating and one penetrating impact velocity is chosen. The impact performance is evaluated by the time taken to arrest the projectile and the backface deformation for the non-penetrating impacts, and by the residual velocity for the penetrating impact tests. All deterministic impact simulations are performed using LS-DYNA. 2-sided clamped targets and lower inter-yarn frictional levels generally resulted in better impact performance.The functionally graded targets generally showed either similar or inferior impact performance than the baseline fabric target configurations for the non-penetrating shots. Some performance improvements were observed for the penetrating shots when the yarn stiffness was progressively decreased through the layers in a direction away from the strike face, with additional performance enhancements achieved by simultaneously reducing the inter-yarn friction.
