The spherically layered media theory has wide applications for electromagnetic wave scattering analysis.Due to the involved Bessel functions,the conventional formulations of spherically layered media theory suffer fro...The spherically layered media theory has wide applications for electromagnetic wave scattering analysis.Due to the involved Bessel functions,the conventional formulations of spherically layered media theory suffer from numerical overflow or underflow when the Bessel function’s order is large,the argument is small or the argument has a large imaginary part.The first two issues have been solved recently by employing small-argument asymptotic formulas of Bessel functions,while the third issue remains unsolved.In this paper,the Bessel functions in the conventional formulation of the theory are replaced by scaled Bessel functions which have good numerical properties for high loss media,and stable formulas are derived.Numerical tests show that this approach can work properly with very high lossy media.Also,this approach can be seamlessly combined with the stable computation method for cases of small argument and large order of Bessel functions.展开更多
The notion of vector-valued multiresolution analysis is introduced and the concept of orthogonal vector-valued wavelets with 3-scale is proposed. A necessary and sufficient condition on the existence of orthogonal vec...The notion of vector-valued multiresolution analysis is introduced and the concept of orthogonal vector-valued wavelets with 3-scale is proposed. A necessary and sufficient condition on the existence of orthogonal vector-valued wavelets is given by means of paraunitary vector filter bank theory. An algorithm for constructing a class of compactly supported orthogonal vector-valued wavelets is presented. Their characteristics is discussed by virtue of operator theory, time-frequency method. Moreover, it is shown how to design various orthonormal bases of space L^2（R, C^n） from these wavelet packets.展开更多
In this paper, the notion of orthogonal vector-valued wavelet packets of space L2 （R^s, C^n） is introduced. A procedure for constructing the orthogonal vector-valued wavelet packets is presented. Their properties ar...In this paper, the notion of orthogonal vector-valued wavelet packets of space L2 （R^s, C^n） is introduced. A procedure for constructing the orthogonal vector-valued wavelet packets is presented. Their properties are characterized by virtue of time-frequency analysis method, matrix theory and finite group theory, and three orthogonality formulas are obtained. Finally, new orthonormal bases of space L2（R^s,C^n） are extracted from these wavelet packets.展开更多
The authors introduce nonseparable scaling function interpolation and show that its approximation can provide similar convergence properties as scalar wavelet system. Several equivalent statements of accuracy of nonse...The authors introduce nonseparable scaling function interpolation and show that its approximation can provide similar convergence properties as scalar wavelet system. Several equivalent statements of accuracy of nonseparable scaling function are also given. In the numerical experiments, it appears that nonseparable scaling function interpolation has better convergence results than scalar wavelet systems in some cases.展开更多
This paper investigates a kind of modified scaling function projective synchronization of uncertain chaotic systems using an adaptive controller. The given scaling function in the new method can be an equilibrium poin...This paper investigates a kind of modified scaling function projective synchronization of uncertain chaotic systems using an adaptive controller. The given scaling function in the new method can be an equilibrium point; a periodic orbit, or even a chaotic attractor in the phase space. Based on LaSalle＇s invariance set principle, the adaptive control law is derived to make the states of two chaotic systems function projective synchronized. Some numerical examples are also given to show the effectiveness of the proposed method.展开更多
Two properties are given in this paper about the scaling function: suppose Vj; j ∈ Z is a multiresolution analysis with a continuous scaling function φ which have compact support set and that φ the Fourier transfor...Two properties are given in this paper about the scaling function: suppose Vj; j ∈ Z is a multiresolution analysis with a continuous scaling function φ which have compact support set and that φ the Fourier transform of φ is a continuous real function, compactly supported, then φ(0) ≠ 0 and when supp φ = [a1,b1]∪[a2,b2](b1 < a2,0 < a2), then we havea1 ≤ 0, 0 < b1, a1 < b2/2 ≤ b1, 2π < b2 - a1 ≤ 8π.展开更多
The notion of a sort of biorthogonal multiple vector-valued bivariate wavelet packets,which are associated with a quantity dilation matrix,is introduced.The biorthogonality property of the multiple vector-valued wavel...The notion of a sort of biorthogonal multiple vector-valued bivariate wavelet packets,which are associated with a quantity dilation matrix,is introduced.The biorthogonality property of the multiple vector-valued wavelet packets in higher dimensions is studied by means of Fourier transform and integral transform biorthogonality formulas concerning these wavelet packets are obtained.展开更多
In this paper, using the orthonormal multiresolution analysis（MRA） of L^2（R^s）, we get two important properties of the scaling function with dilation matrix A = MI of L^2 （R^s）. These properties axe chaxacterize...In this paper, using the orthonormal multiresolution analysis（MRA） of L^2（R^s）, we get two important properties of the scaling function with dilation matrix A = MI of L^2 （R^s）. These properties axe chaxacterized by some inequalities and equalities.展开更多
We present a unified derivation of the pressure equation of states, thermodynamics and scaling functions for the one-dimensional （1D） strongly attractive Fermi gases with SU（w） symmetry. These physical quantities ...We present a unified derivation of the pressure equation of states, thermodynamics and scaling functions for the one-dimensional （1D） strongly attractive Fermi gases with SU（w） symmetry. These physical quantities provide a rigorous understanding on a universality class of quantum criticality characterized by the critical exponents z = 2 and correlation length exponent v= 1/2. Such a universality class of quantum criticality can occur when the Fermi sea of one branch of charge bound states starts to fill or becomes gapped at zero temperature. The quantum critical cone can be determined by the double peaks in specific heat, which serve to mark two crossover temperatures fanning out from the critical point. Our method opens to further study on quantum phases and phase transitions in strongly interacting fermions with large SU （ w） and non-SU （ w ） symmetries in one dimension.展开更多
Diversity-biomass relationships(DBRs)in terrestrial ecosystems tend to vary across spatial scales,but,particularly in hyperdiverse forests,the mechanisms driving these trends remain uncertain.Until now,few have simult...Diversity-biomass relationships(DBRs)in terrestrial ecosystems tend to vary across spatial scales,but,particularly in hyperdiverse forests,the mechanisms driving these trends remain uncertain.Until now,few have simultaneously investigated the connections between tree species diversity,stand structural diversity,mycorrhizal associations,and ecosystem functioning.In addition,DBRs have only been studied at limited spatial scales,with limited focus on the direct and indirect effects of environmental factors.We addressed these research gaps using a 30-ha forest dynamics plot located in Pu'er City,Southwest China.Through piecewise structural equation models,we quantified the direct effects of tree species diversity(α,β,γ),stand structural diversity,mycorrhizal associations(AM,EcM),and the environmental factors(soil fertility and topography),as well as the indirect effects of the environmental factors on aboveground tree biomass across spatial scales ranging from 400 to 230,400 m^(2).We hypothesized that complex interactions among these factors underpin the variation in DBRs in natural ecosystems across spatial scales.Our results showed that environmental conditions indirectly affected the tree biomass via changes in tree species diversity,and these effects became stronger as the spatial scale increased.At small to moderate spatial scales,environmental factors were more predictive of tree biomass than tree species diversity(or its components);the effects of stand structural diversity on biomass also gradually increased with spatial scale.Conversely,from the intermediate to the largest spatial scales,mycorrhizal associations gradually became the best predictors of DBR dynamics.Our research offers novel empirical evidence demonstrating the importance of environmental conditions,structural diversity,and mycorrhizal associations in shaping cross-scale DBRs.Future comprehensive studies should consider these factors to assess the mechanisms shaping scale-dependent DBRs in complex natural ecosystems.展开更多
为应对当今供应链库存管理面临的牛鞭效应、两时间尺度特性和不确定性干扰等挑战,开发了一种基于径向基函数神经网络(radial basis function neural network,RBFNN)的两时间尺度供应链H_(∞)最优控制器。利用奇异摄动理论将原两时间尺...为应对当今供应链库存管理面临的牛鞭效应、两时间尺度特性和不确定性干扰等挑战,开发了一种基于径向基函数神经网络(radial basis function neural network,RBFNN)的两时间尺度供应链H_(∞)最优控制器。利用奇异摄动理论将原两时间尺度供应链模型分解为2个具有不同时间尺度的独立子系统;创新性地使用RBFNN在线近似补偿子系统的不确定项,进而采用H_(∞)控制来抑制RBFNN近似误差带来的不确定性。在理论层面上分析证明了所提方法的稳定性。通过一个电视机生产流程仿真案例,验证了所提方法相比2种其他两时间尺度问题解决方法,具有更高的跟踪控制精度和应用可行性。展开更多
在交通监控中进行车辆检测过程时,存在车辆互相遮挡和远距离目标尺寸不足的问题,导致在检测中存在漏检和误检情况。针对此问题,文中提出一种基于YOLOv4(You Only Look Once version 4)的多尺度融合与注意力机制的交通车辆检测算法。在YO...在交通监控中进行车辆检测过程时,存在车辆互相遮挡和远距离目标尺寸不足的问题,导致在检测中存在漏检和误检情况。针对此问题,文中提出一种基于YOLOv4(You Only Look Once version 4)的多尺度融合与注意力机制的交通车辆检测算法。在YOLOv4的路径聚合网络中增加一个新的特征层进行多尺度特征融合,提升模型对底层纹理特征的提取能力。在YOLO Head检测头前嵌入ECA(Efficient Channel Attention)通道注意力模块,对聚合后的特征进行合理的抑制和增强,将CIoU(Complete Intersection over Union)损失函数替换为Soft-CIoU损失函数,提高小目标车辆对损失函数的贡献度。在公开车辆数据集UA-DETRAC与KITTI中的实验结果表明,相较于原YOLOv4算法,所提算法的平均精度分别提升了2.45百分点和1.14百分点,检测速度达到41.67 frame·s^(-1)。相较于其他先进算法,所提算法在检测精度上表现良好。展开更多
针对在复杂背景下输电线路多尺度缺陷目标检测精度较低的问题,文中提出一种基于改进YOLOv7(You Only Look Once version 7)的输电线路多类缺陷目标检测模型。对于复杂背景造成缺陷目标较低的问题,在Backbone部分引入改进的Swin Transfor...针对在复杂背景下输电线路多尺度缺陷目标检测精度较低的问题,文中提出一种基于改进YOLOv7(You Only Look Once version 7)的输电线路多类缺陷目标检测模型。对于复杂背景造成缺陷目标较低的问题,在Backbone部分引入改进的Swin Transformer模块,通过使用多头注意力机制提升对全局特征的提取效果来提高模型的检测精度。对于待检测目标的多尺度特性,在特征金字塔基础上引入自适应特征融合模块,提升了Neck部分特征融合网络对多类不同尺度缺陷目标的检测能力。使用SIoU(Structured Intersection over Union)损失函数在提高预测框回归精度的同时加快了模型的收敛。实验结果表明,相较于YOLOv5、YOLOv7和Faster R-CNN(Faster Region with Convolutional Neural Network)模型,改进YOLOv7模型具有较高的检测精度,其平均检测精度可达96.4%,检测速度为29.6 frame·s^(-1),能够为输电线路多类缺陷目标检测提供参考。展开更多
文摘The spherically layered media theory has wide applications for electromagnetic wave scattering analysis.Due to the involved Bessel functions,the conventional formulations of spherically layered media theory suffer from numerical overflow or underflow when the Bessel function’s order is large,the argument is small or the argument has a large imaginary part.The first two issues have been solved recently by employing small-argument asymptotic formulas of Bessel functions,while the third issue remains unsolved.In this paper,the Bessel functions in the conventional formulation of the theory are replaced by scaled Bessel functions which have good numerical properties for high loss media,and stable formulas are derived.Numerical tests show that this approach can work properly with very high lossy media.Also,this approach can be seamlessly combined with the stable computation method for cases of small argument and large order of Bessel functions.
基金the Science Research Foundation of Education Department of ShaanxiProvince (08JK340)the Items of Xi’an University of Architecture and Technology(RC0701JC0718)
文摘The notion of vector-valued multiresolution analysis is introduced and the concept of orthogonal vector-valued wavelets with 3-scale is proposed. A necessary and sufficient condition on the existence of orthogonal vector-valued wavelets is given by means of paraunitary vector filter bank theory. An algorithm for constructing a class of compactly supported orthogonal vector-valued wavelets is presented. Their characteristics is discussed by virtue of operator theory, time-frequency method. Moreover, it is shown how to design various orthonormal bases of space L^2（R, C^n） from these wavelet packets.
基金Foundation item： Supported by the Natural Science Foundation of China（10571113）
文摘In this paper, the notion of orthogonal vector-valued wavelet packets of space L2 （R^s, C^n） is introduced. A procedure for constructing the orthogonal vector-valued wavelet packets is presented. Their properties are characterized by virtue of time-frequency analysis method, matrix theory and finite group theory, and three orthogonality formulas are obtained. Finally, new orthonormal bases of space L2（R^s,C^n） are extracted from these wavelet packets.
文摘The authors introduce nonseparable scaling function interpolation and show that its approximation can provide similar convergence properties as scalar wavelet system. Several equivalent statements of accuracy of nonseparable scaling function are also given. In the numerical experiments, it appears that nonseparable scaling function interpolation has better convergence results than scalar wavelet systems in some cases.
基金Project supported by the National Natural Science Foundation of China (Grant No.61075060)the Science and Technology Research Key Program for the Education Department of Hubei Province of China (Grant No.D20105001)the Open Project of State Key Laboratory of Industrial Control Technology,China (Grant No.ICT1007)
文摘This paper investigates a kind of modified scaling function projective synchronization of uncertain chaotic systems using an adaptive controller. The given scaling function in the new method can be an equilibrium point; a periodic orbit, or even a chaotic attractor in the phase space. Based on LaSalle＇s invariance set principle, the adaptive control law is derived to make the states of two chaotic systems function projective synchronized. Some numerical examples are also given to show the effectiveness of the proposed method.
文摘Two properties are given in this paper about the scaling function: suppose Vj; j ∈ Z is a multiresolution analysis with a continuous scaling function φ which have compact support set and that φ the Fourier transform of φ is a continuous real function, compactly supported, then φ(0) ≠ 0 and when supp φ = [a1,b1]∪[a2,b2](b1 < a2,0 < a2), then we havea1 ≤ 0, 0 < b1, a1 < b2/2 ≤ b1, 2π < b2 - a1 ≤ 8π.
基金Supported by Natural Science Foundation of Henan Province（0511013500）
文摘The notion of a sort of biorthogonal multiple vector-valued bivariate wavelet packets,which are associated with a quantity dilation matrix,is introduced.The biorthogonality property of the multiple vector-valued wavelet packets in higher dimensions is studied by means of Fourier transform and integral transform biorthogonality formulas concerning these wavelet packets are obtained.
基金Supported by the Natural Science Foundation of Ningxia Province(NZ0691)
文摘In this paper, using the orthonormal multiresolution analysis（MRA） of L^2（R^s）, we get two important properties of the scaling function with dilation matrix A = MI of L^2 （R^s）. These properties axe chaxacterized by some inequalities and equalities.
基金Supported by the National Natural Science Foundation of China under Grant No 11374331the key NSFC under Grant No11534014partially supported by the Australian Research Council
文摘We present a unified derivation of the pressure equation of states, thermodynamics and scaling functions for the one-dimensional （1D） strongly attractive Fermi gases with SU（w） symmetry. These physical quantities provide a rigorous understanding on a universality class of quantum criticality characterized by the critical exponents z = 2 and correlation length exponent v= 1/2. Such a universality class of quantum criticality can occur when the Fermi sea of one branch of charge bound states starts to fill or becomes gapped at zero temperature. The quantum critical cone can be determined by the double peaks in specific heat, which serve to mark two crossover temperatures fanning out from the critical point. Our method opens to further study on quantum phases and phase transitions in strongly interacting fermions with large SU （ w） and non-SU （ w ） symmetries in one dimension.
基金funded by Fundamental Research Funds of Chinese Academy of Forestry(No.CAFYBB2021ZA002).
文摘Diversity-biomass relationships(DBRs)in terrestrial ecosystems tend to vary across spatial scales,but,particularly in hyperdiverse forests,the mechanisms driving these trends remain uncertain.Until now,few have simultaneously investigated the connections between tree species diversity,stand structural diversity,mycorrhizal associations,and ecosystem functioning.In addition,DBRs have only been studied at limited spatial scales,with limited focus on the direct and indirect effects of environmental factors.We addressed these research gaps using a 30-ha forest dynamics plot located in Pu'er City,Southwest China.Through piecewise structural equation models,we quantified the direct effects of tree species diversity(α,β,γ),stand structural diversity,mycorrhizal associations(AM,EcM),and the environmental factors(soil fertility and topography),as well as the indirect effects of the environmental factors on aboveground tree biomass across spatial scales ranging from 400 to 230,400 m^(2).We hypothesized that complex interactions among these factors underpin the variation in DBRs in natural ecosystems across spatial scales.Our results showed that environmental conditions indirectly affected the tree biomass via changes in tree species diversity,and these effects became stronger as the spatial scale increased.At small to moderate spatial scales,environmental factors were more predictive of tree biomass than tree species diversity(or its components);the effects of stand structural diversity on biomass also gradually increased with spatial scale.Conversely,from the intermediate to the largest spatial scales,mycorrhizal associations gradually became the best predictors of DBR dynamics.Our research offers novel empirical evidence demonstrating the importance of environmental conditions,structural diversity,and mycorrhizal associations in shaping cross-scale DBRs.Future comprehensive studies should consider these factors to assess the mechanisms shaping scale-dependent DBRs in complex natural ecosystems.
文摘为应对当今供应链库存管理面临的牛鞭效应、两时间尺度特性和不确定性干扰等挑战,开发了一种基于径向基函数神经网络(radial basis function neural network,RBFNN)的两时间尺度供应链H_(∞)最优控制器。利用奇异摄动理论将原两时间尺度供应链模型分解为2个具有不同时间尺度的独立子系统;创新性地使用RBFNN在线近似补偿子系统的不确定项,进而采用H_(∞)控制来抑制RBFNN近似误差带来的不确定性。在理论层面上分析证明了所提方法的稳定性。通过一个电视机生产流程仿真案例,验证了所提方法相比2种其他两时间尺度问题解决方法,具有更高的跟踪控制精度和应用可行性。
文摘在交通监控中进行车辆检测过程时,存在车辆互相遮挡和远距离目标尺寸不足的问题,导致在检测中存在漏检和误检情况。针对此问题,文中提出一种基于YOLOv4(You Only Look Once version 4)的多尺度融合与注意力机制的交通车辆检测算法。在YOLOv4的路径聚合网络中增加一个新的特征层进行多尺度特征融合,提升模型对底层纹理特征的提取能力。在YOLO Head检测头前嵌入ECA(Efficient Channel Attention)通道注意力模块,对聚合后的特征进行合理的抑制和增强,将CIoU(Complete Intersection over Union)损失函数替换为Soft-CIoU损失函数,提高小目标车辆对损失函数的贡献度。在公开车辆数据集UA-DETRAC与KITTI中的实验结果表明,相较于原YOLOv4算法,所提算法的平均精度分别提升了2.45百分点和1.14百分点,检测速度达到41.67 frame·s^(-1)。相较于其他先进算法,所提算法在检测精度上表现良好。
文摘针对在复杂背景下输电线路多尺度缺陷目标检测精度较低的问题,文中提出一种基于改进YOLOv7(You Only Look Once version 7)的输电线路多类缺陷目标检测模型。对于复杂背景造成缺陷目标较低的问题,在Backbone部分引入改进的Swin Transformer模块,通过使用多头注意力机制提升对全局特征的提取效果来提高模型的检测精度。对于待检测目标的多尺度特性,在特征金字塔基础上引入自适应特征融合模块,提升了Neck部分特征融合网络对多类不同尺度缺陷目标的检测能力。使用SIoU(Structured Intersection over Union)损失函数在提高预测框回归精度的同时加快了模型的收敛。实验结果表明,相较于YOLOv5、YOLOv7和Faster R-CNN(Faster Region with Convolutional Neural Network)模型,改进YOLOv7模型具有较高的检测精度,其平均检测精度可达96.4%,检测速度为29.6 frame·s^(-1),能够为输电线路多类缺陷目标检测提供参考。
