期刊文献+
共找到50篇文章
< 1 2 3 >
每页显示 20 50 100
Dlung:Unsupervised Few-Shot Diffeomorphic Respiratory Motion Modeling
1
作者 陈培芝 郭逸凡 +1 位作者 王大寒 陈金铃 《Journal of Shanghai Jiaotong university(Science)》 EI 2023年第4期536-545,共10页
Lung image registration plays an important role in lung analysis applications,such as respiratory motion modeling.Unsupervised learning-based image registration methods that can compute the deformation without the req... Lung image registration plays an important role in lung analysis applications,such as respiratory motion modeling.Unsupervised learning-based image registration methods that can compute the deformation without the requirement of supervision attract much attention.However,it is noteworthy that they have two drawbacks:they do not handle the problem of limited data and do not guarantee diffeomorphic(topologypreserving)properties,especially when large deformation exists in lung scans.In this paper,we present an unsupervised few-shot learning-based diffeomorphic lung image registration,namely Dlung.We employ fine-tuning techniques to solve the problem of limited data and apply the scaling and squaring method to accomplish the diffeomorphic registration.Furthermore,atlas-based registration on spatio-temporal(4D)images is performed and thoroughly compared with baseline methods.Dlung achieves the highest accuracy with diffeomorphic properties.It constructs accurate and fast respiratory motion models with limited data.This research extends our knowledge of respiratory motion modeling. 展开更多
关键词 unsupervised few-shot learning respiratory motion modeling diffeomorphic registration
原文传递
Diffeomorphic types of complements of nice point arrangements in CP^l
2
作者 YAU Stephen S.-T. 《Science China Mathematics》 SCIE 2009年第12期2774-2791,共18页
We use a new method to study arrangement in CPl,define a class of nice point arrangements and show that if two nice point arrangements have the same combinatorics,then their complements are diffeomorphic to each other... We use a new method to study arrangement in CPl,define a class of nice point arrangements and show that if two nice point arrangements have the same combinatorics,then their complements are diffeomorphic to each other.In particular,the moduli space of nice point arrangements with same combinatorics in CPl is connected.It generalizes the result on point arrangements in CP3 to point arrangements in CPl for any l. 展开更多
关键词 diffeomorphic type hyperplane arrangement lattice isotopy 14F05 14H30
原文传递
Ashtekar-Kodama Gravity as a Classical and Quantum Extension of Loop Quantum Gravity
3
作者 Jan Helm 《Journal of Modern Physics》 2024年第6期864-937,共74页
This paper presents a new theory of gravity, called here Ashtekar-Kodama (AK) gravity, which is based on the Ashtekar-Kodama formulation of loop quantum gravity (LQG), yields in the limit the Einstein equations, and i... This paper presents a new theory of gravity, called here Ashtekar-Kodama (AK) gravity, which is based on the Ashtekar-Kodama formulation of loop quantum gravity (LQG), yields in the limit the Einstein equations, and in the quantum regime a full renormalizable quantum gauge field theory. The three fundamental constraints (hamiltonian, gaussian and diffeomorphism) were formulated in 3-dimensional spatial form within LQG in Ashtekar formulation using the notion of the Kodama state with positive cosmological constant Λ. We introduce a 4-dimensional covariant version of the 3-dimensional (spatial) hamiltonian, gaussian and diffeomorphism constraints of LQG. We obtain 32 partial differential equations for the 16 variables E<sub>mn</sub> (E-tensor, inverse densitized tetrad of the metric) and 16 variables A<sub>mn</sub> (A-tensor, gravitational wave tensor). We impose the boundary condition: for large distance the E-generated metric g(E) becomes the GR-metric g (normally Schwarzschild-spacetime). The theory based on these Ashtekar-Kodama (AK) equations, and called in the following Ashtekar-Kodama (AK-) gravity has the following properties. • For Λ = 0 the AK equations become Einstein equations, A-tensor is trivial (constant), and the E-generated metric g(E) is identical with the GR-metric g. • When the AK-equations are developed into a Λ-power series, the Λ-term yields a gravitational wave equation, which has only at least quadrupole wave solutions and becomes in the limit of large distance r the (normal electromagnetic) wave equation. • AK-gravity, as opposed to GR, has no singularity at the horizon: the singularity in the metric becomes a (very high) peak. • AK-gravity has a limit scale of the gravitational quantum region 39 μm, which emerges as the limit scale in the objective wave collapse theory of Gherardi-Rimini-Weber. In the quantum region, the AK-gravity becomes a quantum gauge theory (AK quantum gravity) with the Lie group extended SU(2) = ε-tensor-group(four generators) as gauge group and a corresponding covariant derivative. • AK quantum gravity is fully renormalizable, we derive its Lagrangian, which is dimensionally renormalizable, the normalized one-graviton wave function, the graviton propagator, and demonstrate the calculation of cross-section from Feynman diagrams. 展开更多
关键词 Quantum Gravity Loop Quantum Gravity General Relativity Gravitational Wave Gauge Field Theory Graviton Hamiltonian Constraint Gaussian Constraint Diffeomorphism Constraint
下载PDF
基于局部联合熵梯度的双向多分辨率Demons算法 被引量:1
4
作者 王昌 任琼琼 +3 位作者 秦鑫 刘艳 张文超 于毅 《生物医学工程研究》 2018年第2期159-162,172,共5页
针对active demons算法易受到参数设置的影响,无法有效解决大形变场的配准问题,本研究提出了基于局部联合熵梯度的双向多分辨率demons算法。利用在配准过程中两幅图像的互信息不断增加,局部联合熵增大的规律,本研究引入两幅图像局部联... 针对active demons算法易受到参数设置的影响,无法有效解决大形变场的配准问题,本研究提出了基于局部联合熵梯度的双向多分辨率demons算法。利用在配准过程中两幅图像的互信息不断增加,局部联合熵增大的规律,本研究引入两幅图像局部联合熵参数,将图像局部联合熵的梯度附加到demons驱动力中,实现了基于局部联合熵梯度的双向多分辨率demons算法。利用自然图像、MRI图像和CT图像测试本算法的优越性,与active demons,diffeomorphic demons算法进行对比分析,采用均方误差、归一化互相关系数和结构相似度对配准结果进行定量评价。本算法归一化互相关系数和结构相似度最高,均方误差最小。通过分析权重系数的影响和设置合适的参数,本算法可应用于大形变的医学图像配准,具有一定的临床应用价值。 展开更多
关键词 双向 多分辨率配准 局部联合熵 ACTIVE DEMONS diffeomorphic DEMONS
下载PDF
Conservative Currents of Boundary Charges in AdS2+1 Gravity
5
作者 FENG Sze-Shiang WANG Bin MENG Xin-He 《Communications in Theoretical Physics》 SCIE CAS CSCD 2001年第7期33-36,共4页
The boundary charge which constitutes the Virasoro algebra in (2-+ 1)-dirnensional anti-de Sitter gravity is derived by Noether theorem and diffeomorphic invariance. It shows that the boundary charge under discussion ... The boundary charge which constitutes the Virasoro algebra in (2-+ 1)-dirnensional anti-de Sitter gravity is derived by Noether theorem and diffeomorphic invariance. It shows that the boundary charge under discussion recently exhausts all the available independent nontrivial charges. Therefore, for any specific spacetime, the state counting via the central charge of the Virasoro algebra is exact. 展开更多
关键词 BOUNDARY charge diffeomorphic INVARIANCE
下载PDF
Bounding Topology via Geometry,A-Simple Fundamental Groups
6
作者 Xiaochun Rong Xuchao Yao 《Communications in Mathematical Research》 CSCD 2020年第4期489-505,共17页
We call a group A-simple,if it has no non-trivial normal abelian subgroup.We will present finiteness results in controlled topology via geometry on manifolds whose fundamental groups are A-simple.
关键词 A-simple fundamental group collapsing with bounded sectional curvature finiteness of fundamental groups and diffeomorphic types.
下载PDF
Geometric Structures of Stable Time-Variant State Feedback Systems 被引量:2
7
作者 仲锋惟 孙华飞 张真宁 《Journal of Beijing Institute of Technology》 EI CAS 2007年第4期500-504,共5页
A new technique for considering the stabilizing time-variant state feedback gains is proposed from the viewpoint of information geometry. First, parametrization of the set of all stabilizing time-variant state feedbac... A new technique for considering the stabilizing time-variant state feedback gains is proposed from the viewpoint of information geometry. First, parametrization of the set of all stabilizing time-variant state feedback gains is given. Moreover, a diffeomorphic structure between the set of stabilizing time-variant state feedback gains and the Cartesian product of positive definite matrix and skew symmetric matrix satisfying certain algebraic conditions is constructed. Furthermore, an immersion and some results about the eigenvalue locations of stable state feedback systems are derived. 展开更多
关键词 geometric structure state feedback IMMERSION DIFFEOMORPHISM
下载PDF
Vacuum Black Hole Mass Formula Is a Vanishing Noether Charge 被引量:1
8
作者 WU Xiao-Ning GUO Han-Ying HUANG Chao-Guang WU Ke 《Communications in Theoretical Physics》 SCIE CAS CSCD 2002年第9期309-312,共4页
The Noether current and its variation relation with respect to diffeomorphism invariance of gravitationaltheories have been derived from the horizontal variation and vertical-horizontal bi-variation of the Lagrangian,... The Noether current and its variation relation with respect to diffeomorphism invariance of gravitationaltheories have been derived from the horizontal variation and vertical-horizontal bi-variation of the Lagrangian, respec-tively. For Einstein's GR in the stationary, axisymmetric black holes, the mass formula in vacuum can be derived fromthis Noether current although it definitely vanishes. This indicates that the mass formula of black holes is a vanishingNoether charge in this case. The first law of black hole thermodynamics can also be derived from the variation relationof this vanishing Noether current. 展开更多
关键词 black hole mass formula NOETHER charge DIFFEOMORPHISM INVARIANCE
下载PDF
AUTOMATIC SEGMENTATION OF HIPPOCAMPAL SUBFIELDS BASED ON MULTI-ATLAS IMAGE SEGMENTATION TECHNIQUES 被引量:2
9
作者 Shi Yonggang Zhang Xueping Liu Zhiwen 《Journal of Electronics(China)》 2014年第2期121-128,共8页
The volume of hippocampal subfields is closely related with early diagnosis of Alzheimer's disease.Due to the anatomical complexity of hippocampal subfields,automatic segmentation merely on the content of MR image... The volume of hippocampal subfields is closely related with early diagnosis of Alzheimer's disease.Due to the anatomical complexity of hippocampal subfields,automatic segmentation merely on the content of MR images is extremely difficult.We presented a method which combines multi-atlas image segmentation with extreme learning machine based bias detection and correction technique to achieve a fully automatic segmentation of hippocampal subfields.Symmetric diffeomorphic registration driven by symmetric mutual information energy was implemented in atlas registration,which allows multi-modal image registration and accelerates execution time.An exponential function based label fusion strategy was proposed for the normalized similarity measure case in segmentation combination,which yields better combination accuracy.The test results show that this method is effective,especially for the larger subfields with an overlap of more than 80%,which is competitive with the current methods and is of potential clinical significance. 展开更多
关键词 Hippocampal subfields Image segmentation Symmetric diffeomorphism Mutual information Label fusion Extreme Learning Machine(ELM)
下载PDF
Generalized Inverse Analysis on the Domain ?(A, A^+) in B(E,F) 被引量:1
10
作者 Zhaofeng Ma 《Analysis in Theory and Applications》 CSCD 2018年第2期127-134,共8页
Let B(E,F) be the set of all bounded linear operators from a Banach space E into another Banach space F,B^+(E, F) the set of all double splitting operators in B(E, F)and GI(A) the set of generalized inverses of A ∈ B... Let B(E,F) be the set of all bounded linear operators from a Banach space E into another Banach space F,B^+(E, F) the set of all double splitting operators in B(E, F)and GI(A) the set of generalized inverses of A ∈ B^+(E, F). In this paper we introduce an unbounded domain ?(A, A^+) in B(E, F) for A ∈ B^+(E, F) and A^+∈GI(A), and provide a necessary and sufficient condition for T ∈ ?(A, A^+). Then several conditions equivalent to the following property are proved: B = A+(IF+(T-A)A^+)^(-1) is the generalized inverse of T with R(B)=R(A^+) and N(B)=N(A^+), for T∈?(A, A^+), where IF is the identity on F. Also we obtain the smooth(C~∞) diffeomorphism M_A(A^+,T) from ?(A,A^+) onto itself with the fixed point A. Let S = {T ∈ ?(A, A^+) : R(T)∩ N(A^+) ={0}}, M(X) = {T ∈ B(E,F) : TN(X) ? R(X)} for X ∈ B(E,F)}, and F = {M(X) : ?X ∈B(E, F)}. Using the diffeomorphism M_A(A^+,T) we prove the following theorem: S is a smooth submanifold in B(E,F) and tangent to M(X) at any X ∈ S. The theorem expands the smooth integrability of F at A from a local neighborhoold at A to the global unbounded domain ?(A, A^+). It seems to be useful for developing global analysis and geomatrical method in differential equations. 展开更多
关键词 GENERALIZED INVERSE analysis SMOOTH DIFFEOMORPHISM SMOOTH SUBMANIFOLD
下载PDF
EXCESS FUNCTIONS OF RAYS ON COMPLETE NONCOMPACT MANIFOLDS 被引量:1
11
作者 徐森林 徐栩 《Acta Mathematica Scientia》 SCIE CSCD 2003年第3期339-344,共6页
This paper gives an estimate of excess functions of rays on complete non-compact manifolds. By using this estimation, the authors can get the results in [3] as corollaries, which asserts that a complete manifold is di... This paper gives an estimate of excess functions of rays on complete non-compact manifolds. By using this estimation, the authors can get the results in [3] as corollaries, which asserts that a complete manifold is diffeomorphic to Rn under some curvature and pinching conditions. At last, they obtain a refinement of them with extra Ricci condition. 展开更多
关键词 Excess functions RAYS DIFFEOMORPHISM
下载PDF
LOCAL CENTRAL LIMIT THEOREM AND BERRY-ESSEEN THEOREM FOR SOME NONUNIFORMLY HYPERBOLIC DIFFEOMORPHISMS 被引量:1
12
作者 夏红强 《Acta Mathematica Scientia》 SCIE CSCD 2010年第3期701-712,共12页
We prove that, for non-uniformly hyperbolic diffeomorphisms in the sense of Young, the local central limit theorem holds, and the speed in the central limit theorem is O(1/√n).
关键词 Local central limit theorem Berry-Esseen theorem nonuniform hyperbolic diffeomorphism Henon map
下载PDF
Reconsidering “Does the Sum Rule Hold at the Big Bang?” with Pre Planckian HUP, and Division Algebras 被引量:1
13
作者 Andrew W. Beckwith 《Journal of High Energy Physics, Gravitation and Cosmology》 2017年第4期539-557,共19页
In 2012, the author submitted an article to the Prespacetime Journal based upon the premise of inquiry as to the alleged vanishing of disjoint open sets contributing to quantum vector measures no longer working, i.e. ... In 2012, the author submitted an article to the Prespacetime Journal based upon the premise of inquiry as to the alleged vanishing of disjoint open sets contributing to quantum vector measures no longer working, i.e. the solution in 2012 was that the author stated that quantum measures in 4 dimensions would not work, mandating, if measure theory were used, imbedding in higher dimensions was necessary for a singularity. The idea was to use the methodology of String Theory as to come up with a way out of the impasse if higher dimensions do not exist. We revisit this question, taking into account a derived HUP, for metric tensors if we look at Pre-Planckian space-time introducing a pre-quantum mechanical HUP which may be a way to ascertain a solution not mandating higher dimensions, as well as introducing cautions as to what will disrupt the offered solution. Note that first, measurable spaces allow disjoint sets. Also, that smooth relations alone do not define separability or admit sets Planck’s length, if it exists, is a natural way to get about the “bad effects” of a cosmic singularity at the beginning of space-time evolution, but if a development is to be believed, namely by Stoica in the article, about removing the cosmic singularity as a breakdown point in relativity, there is nothing which forbids space-time from collapsing to a point. Without the use of a Pre Planckian HUP, for metric tensors, the quantum measures in four dimensions break down. We try to ascertain if a Pre Planckian HUP is sufficient to avoid this pathology and also look at if division algebras which can link Octonionic geometry and E8, to Quark spinors, in the standard model and add sufficient definition to the standard model are necessary and sufficient conditions for a metric tensor HUP which may remove this breakdown of the sum rule in the onset of the “Big Bang”. 展开更多
关键词 Quantum Measures Spatial DIFFEOMORPHISM Cylinder SETS Caratheodary-Hahn-Huvanek Theorem Big Bang Singularity Causal SETS Modified PRE Planckian HEISENBERG Uncertainty Principle HUP Division ALGEBRAS
下载PDF
Finite Determinacy of High Codimension Smooth Function Germs
14
作者 GAN Wen-liang PEI Dong-he +1 位作者 LI Qiang GAO Rui-mei 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2019年第1期92-99,共8页
Mather gave the necessary and suffcient conditions for the ?nite determinacy smooth function germs with no more than codimension 4. The theorem is very effective on determining low codimension smooth function germs. I... Mather gave the necessary and suffcient conditions for the ?nite determinacy smooth function germs with no more than codimension 4. The theorem is very effective on determining low codimension smooth function germs. In this paper, the concept of right equivalent for smooth function germs ring generated by two ideals ?nitely is de?ned. The containment relationships of function germs still satisfy ?nite k-determinacy under suffciently small disturbance which are discussed in orbit tangent spaces. Furthermore, the methods in judging the right equivalency of Arnold function family with codimension 5 are presented. 展开更多
关键词 function GERM JACOBIAN ideal DIFFEOMORPHISM right EQUIVALENCE
下载PDF
Vacum Black Hole Mass Formula Is a Vanishing Noether Charge
15
作者 WUXiao-Ning HUANGChao-Guang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2002年第3期309-312,共4页
The Noether current and its variation relation with respect to diffeomorphism invariance of gravitational theories have been derived from the horizontal variation and vertical-horizontal bi-variation of the Lagrangian... The Noether current and its variation relation with respect to diffeomorphism invariance of gravitational theories have been derived from the horizontal variation and vertical-horizontal bi-variation of the Lagrangian,respectively.For Einstein's GR in the stationary,axisymmetric black holes,the mass formula in vacuum can be derived from this Noether current although it definitely vanishes.This indicates that the mass formula of black holes is a vanishing Noether charge in this case.The first law of black hole thermodynamics can also be derived from the variation relation of this vanishing Noether current. 展开更多
关键词 black hole mass formula Noether charge diffeomorphism invariance
下载PDF
Global robust output regulation for a class of affine singular nonlinear systems
16
作者 Bomin Huang Lingmei Chen Weiyao Lan 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2017年第4期745-755,共11页
The global robust output regulation problem of the singular nonlinear system is investigated. Motivated by the input-output linearization of the normal affine nonlinear system, a global diffeomorphism map is designed ... The global robust output regulation problem of the singular nonlinear system is investigated. Motivated by the input-output linearization of the normal affine nonlinear system, a global diffeomorphism map is designed under the assumption that the singular nonlinear system has a strong relative degree. The global diffeomorphism map transfers the singular nonlinear system into a new singular nonlinear system with a special structure. Attaching an internal model to the new singular nonlinear system yields an augmented singular nonlinear system and the global robust stabilization solution of the augmented system implies the global robust output regulation solution of the original singular nonlinear system. Then the global stabilization problem is solved by some appropriate assumptions and the solvability conditions of the global robust output regulation problem are established. Finally, a simulation example is given to illustrate the design approach. 展开更多
关键词 singular nonlinear system diffeomorphism map output regulation robust control
下载PDF
FREDHOLM AND COMPACT MAPPINGS SHARING A VALUE
17
作者 J.M.Soriano 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2001年第6期682-686,共5页
Sufficient conditions are given to assert that two differentiable mappings between Banach spaces have common values. The proof is essentially based upon continuation methods.
关键词 zero point continuation methods C 1 HOMOTOPY surjective implicit function theorem compact mapping Fredholm mapping index zero INJECTIVE DIFFEOMORPHISM
下载PDF
A MULTIDIMENSIONAL CENTRAL LIMIT THEOREM WITH SPEED OF CONVERGENCE FOR AXIOM A DIFFEOMORPHISMS
18
作者 夏红强 檀大耀 《Acta Mathematica Scientia》 SCIE CSCD 2011年第3期1123-1132,共10页
Let T:X → X be an Axiom A diffeomorphism,m the Gibbs state for a Hlder continuous function ɡ. Assume that f:X → R^d is a Hlder continuous function with ∫_X^(fdm) = 0.If the components of f are cohomologously i... Let T:X → X be an Axiom A diffeomorphism,m the Gibbs state for a Hlder continuous function ɡ. Assume that f:X → R^d is a Hlder continuous function with ∫_X^(fdm) = 0.If the components of f are cohomologously independent, then there exists a positive definite symmetric matrix σ~2:=σ~2 (f ) such that S^fn √ n converges in distribution with respect to m to a Gaussian random variable with expectation 0 and covariance matrix σ~2 . Moreover, there exists a real number A 〉 0 such that, for any integer n ≥ 1,Π( m*( 1√ nS f n ),N (0,σ~2 ) ≤A√n, where m*(1√ n S^fn)denotes the distribution of 1√ n S^fn with respect to m, and Π is the Prokhorov metric. 展开更多
关键词 multidimensional central limit theorem Axiom A diffeomorphisms symbolic dynamics transfer operator
下载PDF
ON THE SOLUTION OF NONLINEARTWOPOINT BOUNDARY VALUE PROBLEM──u" + g(t.u) = f(t),u(0) = u(2π) = 0
19
作者 黄文华 曹菊生 沈祖和 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1998年第9期889-894,共6页
In this paper, a non-variational version of a max-min principle is proposed, andan existence and uniqueness result is obtained for the nonlinear two-point boundaryvalue problenl u' + g(t.u) = f(t),u(0) = u(2... In this paper, a non-variational version of a max-min principle is proposed, andan existence and uniqueness result is obtained for the nonlinear two-point boundaryvalue problenl u' + g(t.u) = f(t),u(0) = u(2π) = 0 展开更多
关键词 Hilbert space DIFFEOMORPHISM nonlinear two-point boundaryvalue problem unique solution
下载PDF
Local integrable differential systems and their normal forms
20
作者 Shiliang Weng Xiang Zhang 《上海师范大学学报(自然科学版)》 2014年第5期476-485,共10页
In this paper we first summarize our results published in recent years and their sketch proofs on local integrability,which are on the characterization of local integrability and on the existence of analytic normaliza... In this paper we first summarize our results published in recent years and their sketch proofs on local integrability,which are on the characterization of local integrability and on the existence of analytic normalization of analytically integrable differential systems. Then we present a new result on the equivalent characterization of the existence of the first integrals of an analytic differential systems near a nonhyperbolic singularity. Finally we pose some open problems on this subject. 展开更多
关键词 formal diffeomorphism embedding vector field normal form
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部