In this paper,a two-stage light detection and ranging(LiDAR) three-dimensional(3D) object detection framework is presented,namely point-voxel dual transformer(PV-DT3D),which is a transformer-based method.In the propos...In this paper,a two-stage light detection and ranging(LiDAR) three-dimensional(3D) object detection framework is presented,namely point-voxel dual transformer(PV-DT3D),which is a transformer-based method.In the proposed PV-DT3D,point-voxel fusion features are used for proposal refinement.Specifically,keypoints are sampled from entire point cloud scene and used to encode representative scene features via a proposal-aware voxel set abstraction module.Subsequently,following the generation of proposals by the region proposal networks(RPN),the internal encoded keypoints are fed into the dual transformer encoder-decoder architecture.In 3D object detection,the proposed PV-DT3D takes advantage of both point-wise transformer and channel-wise architecture to capture contextual information from the spatial and channel dimensions.Experiments conducted on the highly competitive KITTI 3D car detection leaderboard show that the PV-DT3D achieves superior detection accuracy among state-of-the-art point-voxel-based methods.展开更多
This paper studies the conformal invariance by infinitesimal point transformations of non-conservative Lagrange systems. It gives the necessary and sufficient conditions of conformal invariance by the action of infini...This paper studies the conformal invariance by infinitesimal point transformations of non-conservative Lagrange systems. It gives the necessary and sufficient conditions of conformal invariance by the action of infinitesimal point transformations being Lie symmetric simultaneously. Then the Noether conserved quantities of conformal invariance are obtained. Finally an illustrative example is given to verify the results.展开更多
Acoustic orbital angular momentum(OAM)provides an infinite set of orthogonal bases in Hilbert space and significantly boosts the link capacity and data transmission rate.High-capacity and low-crosstalk OAM detection w...Acoustic orbital angular momentum(OAM)provides an infinite set of orthogonal bases in Hilbert space and significantly boosts the link capacity and data transmission rate.High-capacity and low-crosstalk OAM detection within compact physical space is highly desired to effectively harness this spatial dimension of sound wave,but the existing mechanisms generally either operate only for finite OAMs with predetermined mode orders or rely on complicated active devices.Here,we propose a phase saddle point(PSP)transformation mechanism for distinguishing and demultiplexing acoustic OAM modes in a passive,mode-adaptive,high-efficiency,and high-accuracy paradigm.The phase mask characterized by a PSP in the specific area is created through the single-pass log-polar transformation without prior information of incident modes,whose interaction with incident vortex beams of different OAM modes will yield the translation of the stationary phase point and thereby generate the corresponding focused line spots at distinct lateral positions.We theoretically elucidate the mode-adaptive response of PSP transformation by deriving the quantitative relationship between the OAM order and line spot offset.This mode adaptability enables our mechanism to detect OAM of arbitrary mode orders and mode numbers with the inter-mode crosstalk being effectively suppressed,beyond attainable with the existing methods.The effectiveness of our proposed mechanism is validated by demonstrating several distinct examples of single-mode OAM sorting and multi-mode synthesized vortex beam demultiplexing.We anticipate this modeadaptive methodology,designed for compact dimensions and featuring with low crosstalk and uniform efficiency,will find important applications in OAM information processing.展开更多
We investigate the Painleve integrabiiity of nonautonomous nonlinear Schr6dinger （NLS） equations with both space-and time-dependent dispersion, nonlinearity, and external potentials. The Painleve analysis is carried...We investigate the Painleve integrabiiity of nonautonomous nonlinear Schr6dinger （NLS） equations with both space-and time-dependent dispersion, nonlinearity, and external potentials. The Painleve analysis is carried out without using the Kruskal＇s simplification, which results in more generalized form of inhomogeneous equations. The obtained equations are shown to be reducible to the standard NLS equation by using a point transformation. We also construct the corresponding Lax pair and carry out its Kundu-type reduction to the standard Lax pair. Special cases of equations from choosing limited form of coefficients coincide with the equations from the previous Painleve analyses and/or become unknown new equations.展开更多
We provide a complete set of linearizability conditions for nonlinear partial difference equations defined on four points and, using them, we classify all linearizable multilinear partial difference equations defined ...We provide a complete set of linearizability conditions for nonlinear partial difference equations defined on four points and, using them, we classify all linearizable multilinear partial difference equations defined on four points up to a MSbious transformation.展开更多
In order to meet the actual operation demand of visual navigation during cotton field management period,image detection algorithm of visual navigation route during this period was investigated in this research.Firstly...In order to meet the actual operation demand of visual navigation during cotton field management period,image detection algorithm of visual navigation route during this period was investigated in this research.Firstly,for the operation images under natural environment,the approach of color component difference,which is applicable for cotton field management,was adopted to extract the target characteristics of different regions inside and outside cotton field.Secondly,the median filtering method was employed to eliminate noise in the images and realize smoothing process of the images.Then,according to the regional vertical cumulative distribution graph of the images,the boundary characteristic of the cotton seedling region was obtained and the central position of the cotton seedling row was determined.Finally,the detection of the candidate points cluster was realized,and the navigation route was extracted by Hough transformation passing the known point.The testing results showed that the algorithms could rapidly and accurately detect the navigation route during cotton field management period.And the average processing time periods for each frame image at the emergence,strong seedling,budding and blooming stages were 41.43 ms,67.83 ms,68.80 ms and 74.05 ms,respectively.The detection has the advantage of high accuracy,strong robustness and fast speed,and is simultaneously less vulnerable to interference from external environment,which satisfies the practical operation requirements of cotton field management machinery.展开更多
We present a variable time step,fully adaptive in space,hybrid method for the accurate simulation of incompressible two-phase flows in the presence of surface tension in two dimensions.The method is based on the hybri...We present a variable time step,fully adaptive in space,hybrid method for the accurate simulation of incompressible two-phase flows in the presence of surface tension in two dimensions.The method is based on the hybrid level set/front-tracking approach proposed in[H.D.Ceniceros and A.M.Roma,J.Comput.Phys.,205,391-400,2005].Geometric,interfacial quantities are computed from front-tracking via the immersed-boundary setting while the signed distance(level set)function,which is evaluated fast and to machine precision,is used as a fluid indicator.The surface tension force is obtained by employing the mixed Eulerian/Lagrangian representation introduced in[S.Shin,S.I.Abdel-Khalik,V.Daru and D.Juric,J.Comput.Phys.,203,493-516,2005]whose success for greatly reducing parasitic currents has been demonstrated.The use of our accurate fluid indicator together with effective Lagrangian marker control enhance this parasitic current reduction by several orders of magnitude.To resolve accurately and efficiently sharp gradients and salient flow features we employ dynamic,adaptive mesh refinements.This spatial adaption is used in concert with a dynamic control of the distribution of the Lagrangian nodes along the fluid interface and a variable time step,linearly implicit time integration scheme.We present numerical examples designed to test the capabilities and performance of the proposed approach as well as three applications:the long-time evolution of a fluid interface undergoing Rayleigh-Taylor instability,an example of bubble ascending dynamics,and a drop impacting on a free interface whose dynamics we compare with both existing numerical and experimental data.展开更多
In this paper, we study the property of continuous mappings from a sphere to the Euclidean space. By using the theory of the periodic transformation in algebraic topology, we obtain a generalized Borsuk-Ulam theorem a...In this paper, we study the property of continuous mappings from a sphere to the Euclidean space. By using the theory of the periodic transformation in algebraic topology, we obtain a generalized Borsuk-Ulam theorem and then give some applications of the theorem.展开更多
基金supported by the Natural Science Foundation of China (No.62103298)the South African National Research Foundation (Nos.132797 and 137951)。
文摘In this paper,a two-stage light detection and ranging(LiDAR) three-dimensional(3D) object detection framework is presented,namely point-voxel dual transformer(PV-DT3D),which is a transformer-based method.In the proposed PV-DT3D,point-voxel fusion features are used for proposal refinement.Specifically,keypoints are sampled from entire point cloud scene and used to encode representative scene features via a proposal-aware voxel set abstraction module.Subsequently,following the generation of proposals by the region proposal networks(RPN),the internal encoded keypoints are fed into the dual transformer encoder-decoder architecture.In 3D object detection,the proposed PV-DT3D takes advantage of both point-wise transformer and channel-wise architecture to capture contextual information from the spatial and channel dimensions.Experiments conducted on the highly competitive KITTI 3D car detection leaderboard show that the PV-DT3D achieves superior detection accuracy among state-of-the-art point-voxel-based methods.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10472040, 10572021 and 10772025)the Outstanding Young Talents Training Found of Liaoning Province of China (Grant No 3040005)
文摘This paper studies the conformal invariance by infinitesimal point transformations of non-conservative Lagrange systems. It gives the necessary and sufficient conditions of conformal invariance by the action of infinitesimal point transformations being Lie symmetric simultaneously. Then the Noether conserved quantities of conformal invariance are obtained. Finally an illustrative example is given to verify the results.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1404402 and 2017YFA0303700)the National Natural Science Foundation of China(Grant Nos.12304493 and 12174190)+2 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK 20230767)the High-Performance Computing Center of Collaborative Innovation Center of Advanced Microstructures,a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe support from Young Elite Scientists Sponsorship Program by CAST(Grant No.2023QNRC001)。
文摘Acoustic orbital angular momentum(OAM)provides an infinite set of orthogonal bases in Hilbert space and significantly boosts the link capacity and data transmission rate.High-capacity and low-crosstalk OAM detection within compact physical space is highly desired to effectively harness this spatial dimension of sound wave,but the existing mechanisms generally either operate only for finite OAMs with predetermined mode orders or rely on complicated active devices.Here,we propose a phase saddle point(PSP)transformation mechanism for distinguishing and demultiplexing acoustic OAM modes in a passive,mode-adaptive,high-efficiency,and high-accuracy paradigm.The phase mask characterized by a PSP in the specific area is created through the single-pass log-polar transformation without prior information of incident modes,whose interaction with incident vortex beams of different OAM modes will yield the translation of the stationary phase point and thereby generate the corresponding focused line spots at distinct lateral positions.We theoretically elucidate the mode-adaptive response of PSP transformation by deriving the quantitative relationship between the OAM order and line spot offset.This mode adaptability enables our mechanism to detect OAM of arbitrary mode orders and mode numbers with the inter-mode crosstalk being effectively suppressed,beyond attainable with the existing methods.The effectiveness of our proposed mechanism is validated by demonstrating several distinct examples of single-mode OAM sorting and multi-mode synthesized vortex beam demultiplexing.We anticipate this modeadaptive methodology,designed for compact dimensions and featuring with low crosstalk and uniform efficiency,will find important applications in OAM information processing.
基金supported by the Kyung Hee University on sabbatical leave in 2010
文摘We investigate the Painleve integrabiiity of nonautonomous nonlinear Schr6dinger （NLS） equations with both space-and time-dependent dispersion, nonlinearity, and external potentials. The Painleve analysis is carried out without using the Kruskal＇s simplification, which results in more generalized form of inhomogeneous equations. The obtained equations are shown to be reducible to the standard NLS equation by using a point transformation. We also construct the corresponding Lax pair and carry out its Kundu-type reduction to the standard Lax pair. Special cases of equations from choosing limited form of coefficients coincide with the equations from the previous Painleve analyses and/or become unknown new equations.
文摘We provide a complete set of linearizability conditions for nonlinear partial difference equations defined on four points and, using them, we classify all linearizable multilinear partial difference equations defined on four points up to a MSbious transformation.
基金This work has been financially supported by the National Natural Science Foundation of China(Grant No.31071329)the Team Construction of Young and Middle-aged Talents in Science and Technology Innovation of Xinjiang Corps(Grant No.2016BC001)。
文摘In order to meet the actual operation demand of visual navigation during cotton field management period,image detection algorithm of visual navigation route during this period was investigated in this research.Firstly,for the operation images under natural environment,the approach of color component difference,which is applicable for cotton field management,was adopted to extract the target characteristics of different regions inside and outside cotton field.Secondly,the median filtering method was employed to eliminate noise in the images and realize smoothing process of the images.Then,according to the regional vertical cumulative distribution graph of the images,the boundary characteristic of the cotton seedling region was obtained and the central position of the cotton seedling row was determined.Finally,the detection of the candidate points cluster was realized,and the navigation route was extracted by Hough transformation passing the known point.The testing results showed that the algorithms could rapidly and accurately detect the navigation route during cotton field management period.And the average processing time periods for each frame image at the emergence,strong seedling,budding and blooming stages were 41.43 ms,67.83 ms,68.80 ms and 74.05 ms,respectively.The detection has the advantage of high accuracy,strong robustness and fast speed,and is simultaneously less vulnerable to interference from external environment,which satisfies the practical operation requirements of cotton field management machinery.
基金provided by the National Science Foundation under Grant number DMS 0609996(HDC)by the Fundacao de Amparoa Pesquisa do Estado de Sao Paulo(FAPESP)under Grant numbers 04/13781-1 and 06/57099-5(AMR)the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico(CNPq)under Grant number 155491/2006-7(MMV).
文摘We present a variable time step,fully adaptive in space,hybrid method for the accurate simulation of incompressible two-phase flows in the presence of surface tension in two dimensions.The method is based on the hybrid level set/front-tracking approach proposed in[H.D.Ceniceros and A.M.Roma,J.Comput.Phys.,205,391-400,2005].Geometric,interfacial quantities are computed from front-tracking via the immersed-boundary setting while the signed distance(level set)function,which is evaluated fast and to machine precision,is used as a fluid indicator.The surface tension force is obtained by employing the mixed Eulerian/Lagrangian representation introduced in[S.Shin,S.I.Abdel-Khalik,V.Daru and D.Juric,J.Comput.Phys.,203,493-516,2005]whose success for greatly reducing parasitic currents has been demonstrated.The use of our accurate fluid indicator together with effective Lagrangian marker control enhance this parasitic current reduction by several orders of magnitude.To resolve accurately and efficiently sharp gradients and salient flow features we employ dynamic,adaptive mesh refinements.This spatial adaption is used in concert with a dynamic control of the distribution of the Lagrangian nodes along the fluid interface and a variable time step,linearly implicit time integration scheme.We present numerical examples designed to test the capabilities and performance of the proposed approach as well as three applications:the long-time evolution of a fluid interface undergoing Rayleigh-Taylor instability,an example of bubble ascending dynamics,and a drop impacting on a free interface whose dynamics we compare with both existing numerical and experimental data.
文摘In this paper, we study the property of continuous mappings from a sphere to the Euclidean space. By using the theory of the periodic transformation in algebraic topology, we obtain a generalized Borsuk-Ulam theorem and then give some applications of the theorem.
