期刊文献+
共找到41篇文章
< 1 2 3 >
每页显示 20 50 100
Vertical derivative conversion of irregular-range potential fi eld data based on improved projection onto convex sets method 被引量:1
1
作者 Zeng Xiao-Niu Li Xi-Hai +2 位作者 Yu Xiao-Tong Liu Ji-Hao Liu Dai-Zhi 《Applied Geophysics》 SCIE CSCD 2021年第4期461-472,592,共13页
Gravity and magnetic exploration areas are usually irregular,and there is some data defi ciency.Missing data must be interpolated before the vertical derivative conversion in the wavenumber domain.Meanwhile,for improv... Gravity and magnetic exploration areas are usually irregular,and there is some data defi ciency.Missing data must be interpolated before the vertical derivative conversion in the wavenumber domain.Meanwhile,for improved processing precision,the data need to be edge-padded to the length required by the fast Fourier transform algorithm.For conventional vertical derivative conversion of potential fi eld data(PFD),only vertical derivative conversion is considered,or interpolation,border padding,and vertical derivative conversion are executed independently.In this paper,these three steps are considered uniformly,and a vertical derivative conversion method for irregular-range PFD based on an improved projection onto convex sets method is proposed.The cutoff wavenumber of the filter used in the proposed method is determined by fractal model fi tting of the radial average power spectrum(RAPS)of the potential fi eld.Theoretical gravity models and real aeromagnetic data show the following:(1)The fitting of the RAPS with a fractal model can separate useful signals and noise reasonably.(2)The proposed iterative method has a clear physical sense,and its interpolation,border padding error,and running time are much smaller than those of the conventional kriging and minimum curvature methods. 展开更多
关键词 Potential fi eld vertical derivative projection onto convex sets fractal model
下载PDF
On Drop and Weak Drop Properties for Bounded Closed Convex Sets*
2
作者 张子厚 《Journal of Mathematical Research and Exposition》 CSCD 1999年第4期667-672,共6页
In this paper we prove three equivalent conditions of bounded closed convexset K in Banach space to have the drop and weak drop properties. We also give fourequivalent conditions of Banach space and its dual space to ... In this paper we prove three equivalent conditions of bounded closed convexset K in Banach space to have the drop and weak drop properties. We also give fourequivalent conditions of Banach space and its dual space to have the drop and weak dropproperties. 展开更多
关键词 Bounded closed convex set drop property weak drop property.
下载PDF
Lifts of Non-Compact Convex Sets and Cone Factorizations
3
作者 WANG Chu ZHI Lihong 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2020年第5期1632-1655,共24页
This paper generalizes the factorization theorem of Gouveia,Parrilo and Thomas to a broader class of convex sets.Given a general convex set,the authors define a slack operator associated to the set and its polar accor... This paper generalizes the factorization theorem of Gouveia,Parrilo and Thomas to a broader class of convex sets.Given a general convex set,the authors define a slack operator associated to the set and its polar according to whether the convex set is full dimensional,whether it is a translated cone and whether it contains lines.The authors strengthen the condition of a cone lift by requiring not only the convex set is the image of an affine slice of a given closed convex cone,but also its recession cone is the image of the linear slice of the closed convex cone.The authors show that the generalized lift of a convex set can also be characterized by the cone factorization of a properly defined slack operator. 展开更多
关键词 Cone factorization convex set lift nonnegative rank POLYHEDRON positive semidefinite rank recession cone
原文传递
On Proximinality of Convex Sets in Superspaces
4
作者 Li Xin CHENG Zheng Hua LUO +1 位作者 Wen ZHANG Ben Tuo ZHENG 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2016年第6期633-642,共10页
Abstract In this paper, we show that a closed convex subset C of a Banach space is strongly proximinal (proximinal, resp.) in every Banach space isometrically containing it if and only if C is locally (weakly, resp... Abstract In this paper, we show that a closed convex subset C of a Banach space is strongly proximinal (proximinal, resp.) in every Banach space isometrically containing it if and only if C is locally (weakly, resp.) compact. As a consequence, it is proved that local compactness of C is also equivalent to that for every Banach space Y isometrically containing it, the metric projection from Y to C is nonempty set-valued and upper semi-continuous. 展开更多
关键词 Proximinality convex set local compactness Banach space
原文传递
Structural eigenvalue analysis under the constraint of a fuzzy convex set model 被引量:1
5
作者 Wencai Sun Zichun Yang Guobing Chen 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2018年第4期653-666,共14页
In small-sample problems, determining and controlling the errors of ordinary rigid convex set models are difficult. Therefore, a new uncertainty model called the fuzzy convex set(FCS) model is built and investigated... In small-sample problems, determining and controlling the errors of ordinary rigid convex set models are difficult. Therefore, a new uncertainty model called the fuzzy convex set(FCS) model is built and investigated in detail. An approach was developed to analyze the fuzzy properties of the structural eigenvalues with FCS constraints. Through this method, the approximate possibility distribution of the structural eigenvalue can be obtained. Furthermore, based on the symmetric F-programming theory, the conditional maximum and minimum values for the structural eigenvalue are presented, which can serve as nonfuzzy quantitative indicators for fuzzy problems. A practical application is provided to demonstrate the practicability and effectiveness of the proposed methods. 展开更多
关键词 Structural eigenvalue FUZZY convex set Conditional extreme Symmetric F-programming
下载PDF
CONVEX-MODEL ANALYSIS OF THE SEISMIC RESPONSE
6
作者 何彩英 张景绘 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1997年第10期941-947,共7页
An ellipsoidal Fourier-bound convex model (EFB model) is proposed in the present paper to express the uncertainty of seismic excitation, and several methods of selecting parameters of the model are explained. An analy... An ellipsoidal Fourier-bound convex model (EFB model) is proposed in the present paper to express the uncertainty of seismic excitation, and several methods of selecting parameters of the model are explained. An analytical expression is obtained for the worst response of the single-degree-of-freedom (SDOF) system with the EFB model. A numerical simulation shows that the traditional prediction of maximum response can yield the value substantially lover than that predicted by the EFB model. This means that the traditional designing method based on standard seismic inputs may lead to unsafe design decisions. 展开更多
关键词 seismic response response spectrum convex set extreme value
下载PDF
SOME RESULTS ON BEST APPROXIMATION IN SPACES WITH CONVEX STRUCTURE
7
作者 T. D. Narang 《Analysis in Theory and Applications》 2008年第1期67-73,共7页
Some generalizations of the result proved by S.P. Singh [J. Approx. Theory 25(1979), 89-90] are presented in convex metric spaces. The results proved contain several known results on the subject.
关键词 convex metric space convex set starshaped set non-expansive map affinemap
下载PDF
Convex Set Theory for Reliability Assessment of Steel Beam with Bounded Uncertainty
8
作者 Li-Zhe Jia Yi-Ming Duan 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2014年第2期91-96,共6页
Probabilistic reliability model established by insufficient data is inaccessible. The convex model was applied to model the uncertainties of variables. A new non-probabilistic reliability model was proposed based on t... Probabilistic reliability model established by insufficient data is inaccessible. The convex model was applied to model the uncertainties of variables. A new non-probabilistic reliability model was proposed based on the robustness of system to uncertainty. The non-probabilistic reliability model,the infinite norm model,and the probabilistic model were used to assess the reliability of a steel beam,respectively. The results show that the resistance is allowed to couple with the action effect in the non-probabilistic reliability model. Additionally,the non-probabilistic reliability model becomes the same accurate as probabilistic model with the increase of the bounded uncertain information. The model is decided by the available data and information. 展开更多
关键词 non-probabilistic model convex set theory structural reliability
下载PDF
Seismic data reconstruction based on CS and Fourier theory 被引量:10
9
作者 张华 陈小宏 吴信民 《Applied Geophysics》 SCIE CSCD 2013年第2期170-180,236,共12页
Traditional seismic data sampling follows the Nyquist sampling theorem. In this paper, we introduce the theory of compressive sensing (CS), breaking through the limitations of the traditional Nyquist sampling theore... Traditional seismic data sampling follows the Nyquist sampling theorem. In this paper, we introduce the theory of compressive sensing (CS), breaking through the limitations of the traditional Nyquist sampling theorem, rendering the coherent aliases of regular undersampling into harmless incoherent random noise using random undersampling, and effectively turning the reconstruction problem into a much simpler denoising problem. We introduce the projections onto convex sets (POCS) algorithm in the data reconstruction process, apply the exponential decay threshold parameter in the iterations, and modify the traditional reconstruction process that performs forward and reverse transforms in the time and space domain. We propose a new method that uses forward and reverse transforms in the space domain. The proposed method uses less computer memory and improves computational speed. We also analyze the antinoise and anti-aliasing ability of the proposed method, and compare the 2D and 3D data reconstruction. Theoretical models and real data show that the proposed method is effective and of practical importance, as it can reconstruct missing traces and reduce the exploration cost of complex data acquisition. 展开更多
关键词 Fourier transform compressive sensing (CS) projection onto convex sets (POCS) data reconstruction
下载PDF
LEARNING ALGORITHM OF FEEDFORWARD NEURAL NETWORK WITH HARD LIMITER USED FOR CLASSIFICATION
10
作者 张兆宁 孙雅明 毛鹏 《Transactions of Tianjin University》 EI CAS 1999年第2期14-18,共5页
A learning algorithm based on a hard limiter for feedforward neural networks (NN) is presented,and is applied in solving classification problems on separable convex sets and disjoint sets.It has been proved that the a... A learning algorithm based on a hard limiter for feedforward neural networks (NN) is presented,and is applied in solving classification problems on separable convex sets and disjoint sets.It has been proved that the algorithm has stronger classification ability than that of the back propagation (BP) algorithm for the feedforward NN using sigmoid function by simulation.What is more,the models can be implemented with lower cost hardware than that of the BP NN.LEARNIN 展开更多
关键词 hard limiter separable convex sets HYPERPLANE feedforward NN classification learning algorithm
下载PDF
An algorithm for computed tomography image reconstruction from limited-view projections 被引量:5
11
作者 王林元 李磊 +3 位作者 闫镔 江成顺 王浩宇 包尚联 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第8期642-647,共6页
With the development of the compressive sensing theory, the image reconstruction from the projections viewed in limited angles is one of the hot problems in the research of computed tomography technology. This paper d... With the development of the compressive sensing theory, the image reconstruction from the projections viewed in limited angles is one of the hot problems in the research of computed tomography technology. This paper develops an iterative algorithm for image reconstruction, which can fit the most cases. This method gives an image reconstruction flow with the difference image vector, which is based on the concept that the difference image vector between the reconstructed and the reference image is sparse enough. Then the l1-norm minimization method is used to reconstruct the difference vector to recover the image for flat subjects in limited angles. The algorithm has been tested with a thin planar phantom and a real object in limited-view projection data. Moreover, all the studies showed the satisfactory results in accuracy at a rather high reconstruction speed. 展开更多
关键词 limited-view problem computed tomography image reconstruction algorithms reconstruction-reference difference algorithm adaptive steepest descent-projection onto convex sets algorithm
下载PDF
Iterative analytic extension in tomographic imaging
12
作者 Gengsheng L.Zeng 《Visual Computing for Industry,Biomedicine,and Art》 EI 2022年第1期44-56,共13页
If a spatial-domain function has a finite support,its Fourier transform is an entire function.The Taylor series expansion of an entire function converges at every finite point in the complex plane.The analytic continu... If a spatial-domain function has a finite support,its Fourier transform is an entire function.The Taylor series expansion of an entire function converges at every finite point in the complex plane.The analytic continuation theory suggests that a finite-sized object can be uniquely determined by its frequency components in a very small neighborhood.Trying to obtain such an exact Taylor expansion is difficult.This paper proposes an iterative algorithm to extend the measured frequency components to unmeasured regions.Computer simulations show that the proposed algorithm converges very slowly,indicating that the problem is too ill-posed to be practically solvable using available methods. 展开更多
关键词 Analytic continuation Entire function Iterative projections onto convex sets algorithm Image reconstruction Limited angle tomography
下载PDF
Optimization Processes of Tangible and Intangible Networks through the Laplace Problems for Regular Lattices with Multiple Obstacles along the Way
13
作者 Giuseppe Caristi Sabrina Lo Bosco 《Journal of Business Administration Research》 2020年第3期30-41,共12页
A systematic approach is proposed to the theme of safety,reliability and global quality of complex networks(material and immaterial)by means of special mathematical tools that allow an adequate geometric characterizat... A systematic approach is proposed to the theme of safety,reliability and global quality of complex networks(material and immaterial)by means of special mathematical tools that allow an adequate geometric characterization and study of the operation,even in the presence of multiple obstacles along the path.To that end,applying the theory of graphs to the problem under study and using a special mathematical model based on stochastic geometry,in this article we consider some regular lattices in which it is possible to schematize the elements of the network,with the fundamental cell with six,eight or 2(n+2)obstacles,calculating the probability of Laplace.In this way it is possible to measure the“degree of impedance”exerted by the anomalies along the network by the obstacles examined.The method can be extended to other regular and/or irregular geometric figures,whose union together constitutes the examined network,allowing to optimize the functioning of the complex system considered. 展开更多
关键词 Mathematical models Tangible and intangible network infrastructures Safety Reliability Stochastic geometry Random sets Random convex sets and Integral geometry Logistics and transport Social Network Analysis WEB resilience analysis critical network infrastructure transport systems simulation EMERGENCY
下载PDF
NEW METHODS FOR CHARACTERIZING D-η-PROPERLY PREQUASI-INVEX FUNCTIONS 被引量:4
14
作者 Luo Hezhi Wu Huixian Zhu Yihua 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2006年第1期107-112,共6页
The D-η-proper prequasi invexity of vector-valued functions is characterized by means of (weak) nearly convexity and density of sets. Under weaker assumptions, some equivalent conditions for D-η-proper prequasi-in... The D-η-proper prequasi invexity of vector-valued functions is characterized by means of (weak) nearly convexity and density of sets. Under weaker assumptions, some equivalent conditions for D-η-proper prequasi-invexity are derived. 展开更多
关键词 D-η-properly prequasi-invex function (weak) nearly convex set invex set lower D-semicontinuity density.
下载PDF
A Comprehensive Model for Structural Non-Probabilistic Reliability and the Key Algorithms 被引量:2
15
作者 Wencai Sun Zichun Yang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2020年第4期309-332,共24页
It is very difficult to know the exact boundaries of the variable domain for problems with small sample size,and the traditional convex set model is no longer applicable.In view of this,a novel reliability model was p... It is very difficult to know the exact boundaries of the variable domain for problems with small sample size,and the traditional convex set model is no longer applicable.In view of this,a novel reliability model was proposed on the basis of the fuzzy convex set(FCS)model.This new reliability model can account for different relations between the structural failure region and variable domain.Key computational algorithms were studied in detail.First,the optimization strategy for robust reliability is improved.Second,Monte Carlo algorithms(i.e.,uniform sampling method)for hyper-ellipsoidal convex sets were studied in detail,and errors in previous reports were corrected.Finally,the Gauss-Legendre integral algorithm was used for calculation of the integral reliability index.Three numerical examples are presented here to illustrate the rationality and feasibility of the proposed model and its corresponding algorithms. 展开更多
关键词 Structural reliability NON-PROBABILISTIC fuzzy convex set robust reliability volume ratio-based reliability Monte Carlo Gauss-Legendre integral formula
下载PDF
Application of a Fast Connected Components Labeling Algorithm in Processing Landmark Images 被引量:2
16
作者 闫士举 王成焘 +2 位作者 陈统一 袁文 苏颖颖 《Journal of Shanghai Jiaotong university(Science)》 EI 2007年第3期383-387,393,共6页
Extracting geometric data of landmarks from fluoroscopic images plays an important role in camera calibration process of a fluoroscopic-image-based surgical navigation system. Connected components labeling is the esse... Extracting geometric data of landmarks from fluoroscopic images plays an important role in camera calibration process of a fluoroscopic-image-based surgical navigation system. Connected components labeling is the essential technique for the extraction. A new fast connected components labeling algorithm was presented. The definition of upward concave set was introduced to explain the algorithm. Feasibility and efficiency of the algorithm were verified with experiments. This algorithm performs well in labeling non-upward concave set connected components and applies to landmarks labeling well. Moreover, the proposed algorithm possesses a desirable characteristic that will facilitate the subsequent processing of fluoroscopic images. 展开更多
关键词 C-ARM surgical navigation system connected components labeling convex set
下载PDF
Gaussian Curvature Estimates for the Convex Level Sets of Solutions for Some Nonlinear Elliptic Partial Differential Equations 被引量:3
17
作者 WANG Peihe ZHANG Wei 《Journal of Partial Differential Equations》 2012年第3期239-275,共37页
We give lower bound estimates for the Gaussian curvature of convex level sets of minimal surfaces and the solutions to semilinear elliptic equations in terms of the norm of boundary gradient and the Gaussian curvature... We give lower bound estimates for the Gaussian curvature of convex level sets of minimal surfaces and the solutions to semilinear elliptic equations in terms of the norm of boundary gradient and the Gaussian curvature of the boundary. 展开更多
关键词 Gaussian curvature estimates convex level sets minimal surface semilinear elliptic equation maximum principle.
原文传递
Efficient Inverse Method for Structural Identification Considering Modeling and Response Uncertainties 被引量:1
18
作者 Lixiong Cao Jie Liu +1 位作者 Cheng Lu Wei Wang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2022年第5期150-161,共12页
The inverse problem analysis method provides an effective way for the structural parameter identification.However,uncertainties wildly exist in the practical engineering inverse problems.Due to the coupling of multi-s... The inverse problem analysis method provides an effective way for the structural parameter identification.However,uncertainties wildly exist in the practical engineering inverse problems.Due to the coupling of multi-source uncertainties in the measured responses and the modeling parameters,the traditional inverse method under the deterministic framework faces the challenges in solving mechanism and computing cost.In this paper,an uncertain inverse method based on convex model and dimension reduction decomposition is proposed to realize the interval identification of unknown structural parameters according to the uncertain measured responses and modeling parameters.Firstly,the polygonal convex set model is established to quantify the epistemic uncertainties of modeling parameters.Afterwards,a space collocation method based on dimension reduction decomposition is proposed to transform the inverse problem considering multi-source uncertainties into a few interval inverse problems considering response uncertainty.The transformed interval inverse problem involves the two-layer solving process including interval propagation and optimization updating.In order to solve the interval inverse problems considering response uncertainty,an efficient interval inverse method based on the high dimensional model representation and affine algorithm is further developed.Through the coupling of the above two strategies,the proposed uncertain inverse method avoids the time-consuming multi-layer nested calculation procedure,and then effectively realizes the uncertainty identification of unknown structural parameters.Finally,two engineering examples are provided to verify the effectiveness of the proposed uncertain inverse method. 展开更多
关键词 Inverse problem Uncertainty quantification Dimension reduction decomposition Polygonal convex set Affine algorithm
下载PDF
A NOVEL ALGORITHM OF SUPER-RESOLUTION RECONSTRUCTION FOR COMPRESSED VIDEO 被引量:1
19
作者 Xu Zhongqiang Zhu Xiuchang 《Journal of Electronics(China)》 2007年第3期363-368,共6页
Super-Resolution (SR) technique means to reconstruct High-Resolution (HR) images from a sequence of Low-Resolution (LR) observations,which has been a great focus for compressed video. Based on the theory of Projection... Super-Resolution (SR) technique means to reconstruct High-Resolution (HR) images from a sequence of Low-Resolution (LR) observations,which has been a great focus for compressed video. Based on the theory of Projection Onto Convex Set (POCS),this paper constructs Quantization Constraint Set (QCS) using the quantization information extracted from the video bit stream. By combining the statistical properties of image and the Human Visual System (HVS),a novel Adaptive Quantization Constraint Set (AQCS) is proposed. Simulation results show that AQCS-based SR al-gorithm converges at a fast rate and obtains better performance in both objective and subjective quality,which is applicable for compressed video. 展开更多
关键词 Super-Resolution (SR) Compressed video Projection Onto convex Set (POCS) Quantization Constraint Set (QCS)
下载PDF
Lipschitz-continuity of Spherically Convex Functions 被引量:1
20
作者 Yin ZHANG Qi GUO 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2023年第2期363-374,共12页
In this article,some basic and important properties of spherically convex functions,such as the Lipschitz-continuity,are investigated.It is shown that,under a weaker condition,every family of spherically convex functi... In this article,some basic and important properties of spherically convex functions,such as the Lipschitz-continuity,are investigated.It is shown that,under a weaker condition,every family of spherically convex functions is equi-Lipschitzian on each closed spherically convex subset contained in the relative interior of their common domain,and from which a powerful result is derived:the pointwise convergence of a sequence of spherically convex functions implies its uniform convergence on each closed spherically convex subset contained in the relative interior of their common domain. 展开更多
关键词 Spherically convex set spherically convex function Lipschitz-continuity uniform convergence
原文传递
上一页 1 2 3 下一页 到第
使用帮助 返回顶部