中国科学院数学与系统科学研究院期刊网

14 June 2026, Volume 47 Issue 2
    

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  • Chen Huixin, Hu Dan
    Journal on Numerica Methods and Computer Applications. 2026, 47(2): 137-159. https://doi.org/10.12288/szjs.s2025-1023
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    This paper proposes the L2_∞ norm for generating adversarial examples, which achieves an effective balance between the L2 and L norms. Leveraging the geometric interpretation of the L2_∞ norm, we analyze its advantages in adversarial attack optimization. The optimization method based on this new norm can stably generate adversarial examples. Numerical experiments demonstrate that the proposed norm significantly improves the transferability and visual imperceptibility of adversarial perturbations. A series of experiments validate the superior performance of perturbations obtained under the L2_∞ norm.
  • Wang Mengsa, Hou Enze, Wang Han
    Journal on Numerica Methods and Computer Applications. 2026, 47(2): 160-183. https://doi.org/10.12288/szjs.s2025-1040
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    Machine learning-based methods have advanced electronic structure calculations in groundstate, excited-state, and time-dependent multi-electron systems. For ground states, neural network wave functions with Slater-Jastrow-Backflow forms, trained via variational Monte Carlo, accurately capture electron correlation, achieving precision comparable to or exceeding coupled-cluster approaches. In excited-state calculations, techniques such as state-averaged penalties and natural excited-state variational principles enforce orthogonality and enable accurate prediction of excitation energies and oscillator strengths for atoms and molecules. For time-dependent systems, the time-dependent variational Monte Carlo method, which evolves parameterized wave functions, precisely simulates electron dynamics under strong fields and captures non-equilibrium effects. Integrating pseudopotential with neural networks improves computational efficiency while maintaining accuracy in complex systems, including those with transition metals. These developments highlight the strong representational capacity of neural quantum states and their applicability across diverse quantum chemistry problems, offering effective tools for high-accuracy simulations in physical and chemical sciences.
  • Chen Jingrun, Sun Yifei
    Journal on Numerica Methods and Computer Applications. 2026, 47(2): 184-204. https://doi.org/10.12288/szjs.s2025-1045
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    The Random Feature Method (RFM) is an emerging framework for solving partial differential equations (PDEs). It constructs function spaces for approximating solutions through shallow neural networks, combining the rigor of traditional numerical methods with the flexibility of modern machine learning. In this work, we design and implement a high-performance RFM solver, pyRFM, based on the Python programming language. In terms of framework design, pyRFM provides a complete workflow that covers key components including geometry representation and sampling, feature matrix assembly and equation solving, as well as result visualization, thereby enabling a systematic process from modeling to numerical experiments. Meanwhile, the software is developed with careful consideration of the intrinsic characteristics of RFM, leveraging widely used and well-supported Python scientific computing libraries to ensure ease of use and extensibility. Moreover, pyRFM is fully compatible with both CPU and GPU computing environments, and its entire workflow is free from traditional mesh-based operations, which grants it higher flexibility and efficiency when handling complex geometries.
  • Li Dongfang
    Journal on Numerica Methods and Computer Applications. 2026, 47(2): 205-223. https://doi.org/10.12288/szjs.s2025-1058
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    This paper reviews some of the recent developments in energy-conserving or energystable schemes. It mainly focuses on the relaxation-type schemes. The key is to introduce the relaxation idea and governing equation into some schemes, taking into account the characteristics of the model. The relaxation parameter is determined by the governing equation based on energy conservation or dissipation. On one hand, the governning equation ensures the local existence and uniqueness of the relaxation parameter; on the other hand, it guarantees the structure-preserving properties of the algorithm. Moreover, based on the estimation of the relaxation parameter, the consistency of the relaxation algorithm is derived. Finally, some applications of the algorithm to nonlinear stiff ordinary differential equations and some partial differential equations are discussed.
  • Li Jinliang, Tang Qinglin, Zhang Qian
    Journal on Numerica Methods and Computer Applications. 2026, 47(2): 224-235. https://doi.org/10.12288/szjs.s2025-1061
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    This study improves the source iteration method to solve the steady-state neutron transport equation and analyze neutron behavior. The method discretizes energy using the group method, angle via discrete ordinates, and space with a discontinuous finite element scheme incorporating an upwind flux. The key improvement involves assembling neutron fluxes for all angles and energy groups into a coupled matrix system, retaining interaction terms between different groups and angles. Validation using KUCA experiments and the NEACRP-L-330 benchmark demonstrates that the enhanced method achieves higher accuracy in calculating the effective multiplication factor and average neutron flux while reducing computational time. This provides an efficient approach for solving neutron transport problems.
  • Sun Li, Zhou Huifang, Chen Wenjia, Feng Wei
    Journal on Numerica Methods and Computer Applications. 2026, 47(2): 236-244. https://doi.org/10.12288/szjs.s2025-0998
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    The decomposition results are unstable when applying nonnegative matrix factorization to the spectral unmixing of hyperspectral remote sensing images. This paper proposes a perturbation-based minimum volume-constrained nonnegative matrix factorization model to address the problem of weak linear correlation in the column vectors of the endmember matrix (base matrix) in unmixing. Simultaneously introducing a multi-layer structure, a deep minimum volume-constrained nonnegative matrix factorization algorithm was designed. The numerical results indicate that introducing disturbance terms effectively avoids the algorithm working with singular accuracy, and the multi-layer decomposition algorithm obtains more accurate endmember spectral information than the single-layer decomposition algorithm. This study provides an effective solution strategy for spectral unmixing problems with similar endmember spectra. Also, it provides a reference for interpretable machine learning methods by designing regularization terms based on specific problems.
  • Gao Miaomiao, Liu Dongjie
    Journal on Numerica Methods and Computer Applications. 2026, 47(2): 245-254. https://doi.org/10.12288/szjs.s2025-1000
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    We mainly consider the adaptive coupling of the finite element method and natural boundary element method for the Signorini transmission problem. First, the variational formulation of the original problem and its discrete formulation are presented. Then, a priori and a posteriori error estimates for the coupling method are provided in the new framework. Finally, numerical experiments validate the theoretical analysis results.
  • Dong Yan, Wang Weiguo
    Journal on Numerica Methods and Computer Applications. 2026, 47(2): 255-270. https://doi.org/10.12288/szjs.s2025-1004
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    Principal component analysis (PCA) has been the most classic and widely used dimensionality reduction method, but it may not be able to accurately capture the essential structure of the data which containing noise or outliers. This paper proposes an adaptive weighted robust sparse principal component analysis method (AWRSPCA), which skillfully integrates the properties of nonconvex penalty function and generalized mean, aiming at inducing sparsity of principal components, i.e., making the principal components more focused on a few key variables, thus enhancing their interpretability. Meanwhile, the method effectively reduces the sensitivity of PCA to noise and outliers by generalized mean, ensuring the robustness of the principal component extraction process. An alternating direction multiplier method is developed for computing the solution of AWRSPCA and the convergence of the algorithm is proved. To verify the effectiveness of the proposed method, we compare the method with several mainstream methods on both synthetic and real datasets. The experimental results show that the new algorithm excels in both sparsity and robustness, not only successfully extracting the key information in the data, but also effectively resisting the interference of noise and outliers.
  • Li Dongyi, Lu Yibin
    Journal on Numerica Methods and Computer Applications. 2026, 47(2): 271-286. https://doi.org/10.12288/szjs.s2025-1005
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    This paper presents a numerical method based on the charge simulation method for calculating conformal mappings from the bounded multiply connected regions with a rectilinear slit onto the three category canonical slit domains. Firstly, the rectilinear slit is expanded by using the pre-map function, and the bounded multiply connected regions with a rectilinear slit is mapped onto the regular slit domains of straight slit, spiral slit and a disc with spiral domains. On this basis, the corresponding set of constraint equations is established by using the Dirichlet boundary conditions, and for the pathological matrix in the set of constraint equations, it is proposed to solve the charges by using the iterative method of stabilized bi-conjugate gradient based on LU decomposition (LU-BiCGSTAB), which improves the accuracy of the conformal mapping function. Secondly, the conformal mapping computational method proposed in this paper is applied to the simulation of the bypassing of a spiral point vortex around a bounded region with linear obstacles. Finally, corresponding numerical experiments are given to demonstrate the effectiveness of the method.
  • Xu Bo, Zhang Lei
    Journal on Numerica Methods and Computer Applications. 2026, 47(2): 287-298. https://doi.org/10.12288/szjs.s2025-1006
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    Neural operators have garnered significant attention in recent years as a powerful framework for learning the mapping between parameter spaces and solution spaces of partial differential equations (PDEs). This paper proposes a novel U-Net variant neural operator based on dilated convolutions, termed U-DNet. The network fully leverages the multi-grid structure of U-Net for multi-scale feature extraction and fusion, while innovatively incorporating dilated convolutions to effectively enhance feature extraction capabilities at each scale. To validate the model’s performance, we conducted systematic experiments on multiple benchmark datasets, including multi-scale elliptic equations, Navier-Stokes equations, and Helmholtz equations. Experimental results demonstrate that U-DNet achieves significant advantages in both prediction accuracy and computational efficiency, highlighting its great potential as a multi-scale operator learning method.