中国科学院数学与系统科学研究院期刊网

14 November 2024, Volume 46 Issue 4
    

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  • Ren Yunyun, Liu Dongjie
    Mathematica Numerica Sinica. 2024, 46(4): 397-408. https://doi.org/10.12286/jssx.j2023-1158
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    The article consider hybrid high-order methods (HHO) for the p-Laplace problem when 1$ < p < \infty$. The approximation by HHO methods utilizes a reconstruction of the gradients with piecewise Raviart-Thomas finite elements on a regular triangulation without stabilization. Using high-order gradient $\mathbf{Ru_{h}}$ for local gradient reconstruction in piecewise Raviart Thomas finite element space instead of gradient $\mathbf{Dv}$. From the perspective of energy, we perform gradient reconstruction on the minimum value of discrete energy, and determine the discrete stress in a new framework of distance. The main results are the a priori and a posteriori error estimates with global upper bound and global lower bound. Numerical benchmarks display higher convergence rates for the HHO method.
  • Fan Zhencheng
    Mathematica Numerica Sinica. 2024, 46(4): 409-423. https://doi.org/10.12286/jssx.j2023-1159
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    The numerical methods of highly nonlinear stochastic differential equations can be divided into two types: explicit methods and implicit methods. In general, the explicit method has cheap computational cost but the stable property is bad, in contrast, the implicit method has good stable property but computational cost is expensive. In this paper, we present the implicit partially truncated Euler-Maruyama method and prove that it is strongly convergent and stable in mean-square sense. In addition, the obtained results show that the presented method has approximate computational cost and better stable property compared with the explicit partially truncated Euler-Maruyama method for the case that the drift coefficient contains a linear function, that is, it posses concurrently the merit of explicit and implicit methods.
  • Lyu Huan, Zhong Shuiming, Wang Baowei, Xue Yu, Liu Qi
    Mathematica Numerica Sinica. 2024, 46(4): 424-448. https://doi.org/10.12286/jssx.j2023-1164
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    With the rise of the AI technology revolution represented by ChatGPT, data-center AI research is rapidly emerging. Data analysis techniques including linear separability have received increasing attention from researchers. Linear separability is a fundamental mathematical problem in data analysis, but in the current big data era, an efficient method for testing linear separability is still an unsatisfied demand. This paper proposes and proves a sufficient and necessary condition for the linear separability between a point and a set based on the sphere model; and based on this necessary and sufficient condition, a parallel rapid preliminary screening method for determining the linear separability between two sets is further proposed and demonstrated. The advantages of the method proposed in this paper are: (1) its inherent parallelization properties enable low time complexity in implementation and more efficiency compared to the existing methods; and (2) the universality of the parallel framework. Any method for determining linear separability can be accelerated using the parallel framework described in this paper. The verification experiments based on benchmark data sets and artificial data sets in this paper also fully demonstrate the accuracy of the method of this paper and the efficiency in implementation.
  • Lin Yanhong, Wang Ran, Zhang Ran, Kang Tong
    Mathematica Numerica Sinica. 2024, 46(4): 449-468. https://doi.org/10.12286/jssx.j2023-1168
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    he purpose of this paper is to reconstruct the diffusive viscous wave equation with timevarying sources. The source can be divided into an unknown temporal part and a known spatial part. The unknown part is determined by additional detection values within a nonglobal scope. We propose a source reconstruction method based on the additional detection values and prove the existence and uniqueness of the weak solution. Finally, the theoretical results are verified through numerical examples.
  • Hu Wenyu, Xu Weiru
    Mathematica Numerica Sinica. 2024, 46(4): 469-481. https://doi.org/10.12286/jssx.j2023-1169
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    In this paper, we consider the generalized double dimensional inverse eigenvalue problem for a kind of pseudo-Jacobi matrices, which is reconstructed from the eigenvalues of these matrices and their $r$×$r$ leading principle submatrices. The eigenvalue distribution of this kind of matrices is related to the size relationship between the eigenvalues of two complementary principle submatrices. When the size relationship is different, the eigenvalue distribution of this kind of matrices will change greatly. Therefore, the eigenvalue distribution of these matrices is discussed according to the distribution of the root of the secular equation, and the necessary and sufficient conditions for the problem to have a solution are given. Then the problem is solved by equivalently converting such a problem into the $k$ problem proposed by Erxiong Jiang. Finally, two numerical examples are given to verify the effectiveness and feasibility of the proposed algorithm.
  • Zhang Dongmei, Ye Minglu
    Mathematica Numerica Sinica. 2024, 46(4): 482-500. https://doi.org/10.12286/jssx.j2024-1174
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    The Multiple-sets Split Feasibility Problem (MSSFP) is an extension of the Split Feasibility Problem and found applications in many practical problems, such as, image reconstruction and phase recovery. Based on selection techniques, Yao et al. [Optimization,2020,69(2): 269-281] proposed two projection algorithms (SPA) for solving MSSFP in Hilbert space. In this paper, we modify the step-size parameter of SPA and present two modified inertial projection algorithms (MISPA) for solving MSSFP. The weak and strong convergence of MISPA are established, respectively, whenever the solution set of MSSFP is nonempty. Numerical experiments are used to show the feasibility of MISPA. Moreover, inertial technique can be used to accelerate SPA.
  • You Guoqiao, Liu Manxi, Ke Yilong
    Mathematica Numerica Sinica. 2024, 46(4): 501-515. https://doi.org/10.12286/jssx.j2024-1178
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    Radial basis function neural network (RBFNN) is a method applied to interpolation and classification prediction. In this article, we propose an improved algorithm for the RBFNN, based on the singular value decomposition (SVD) technique, in order to greatly simplify the network structure. In particular, the proposed algorithm is able to automatically choose core neurons in the hidden layer, while deleting redundant ones, which can therefore save the CPU memory and computational cost. Meanwhile, we propose to use the $K$-fold cross validation method to determine the radial parameter $\varepsilon$ in RBF, to keep the algorithm accuracy. More importantly, there is no need to load all the sample data into the CPU memory. Instead, we propose to load and deal with the sample data row by row, based on the approximate SVD algorithm proposed by Halko in [2]. All numerical experiments show that, our proposed algorithm greatly improve the computational efficiency and simplify the RBFNN structure, compared to the traditional RBFNN, while not losing the computational accuracy.
  • Qin Fangfang, Zhang Jinjin, Ji Haifeng, Chen Yanping
    Mathematica Numerica Sinica. 2024, 46(4): 516-528. https://doi.org/10.12286/jssx.j2024-1193
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    Immersed finite element methods are a group of effective numerical methods for solving interface problems using unfitted meshes. Currently, there are many works on immersed finite element methods for solving interface problems with traditional interface jump conditions. However, there is limited research on interface problems with Robin type jump conditions. In this paper, an immersed finite element method is proposed for solving one-dimensional interface problems with Robin-type jump conditions. The optimal approximation properties and the optimal convergence of the proposed immersed finite element method are proved rigorously. Some numerical examples are provided to validate the theoretical results.
  • Chen Bingxu, Kou Caixia, Chen Shengjie
    Mathematica Numerica Sinica. 2024, 46(4): 529-546. https://doi.org/10.12286/jssx.j2024-1199
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    The Bordered Block Diagonal (BBD) method is a classical approach for solving the largescale sparse linear equation systems generated in transient analysis of circuits simulations. In this paper, a new BBD method is proposed, which improves upon the traditional BBD method by addressing the issue of load imbalance through a combination of basic column decomposition and pipelined decomposition. During the matrix boundary decomposition, the introduction of pipelined decomposition overcomes the difficulty in parallelizing boundaries in traditional methods. By solving the large-scale sparse linear equations generated from 16 real-world circuits, we have verified the effectiveness of the improved BBD method. Compared to the traditional BBD method, the improved method has certain improvements in solution speed with various numbers of parallel threads.