中国科学院数学与系统科学研究院期刊网

28 September 2026, Volume 49 Issue 5
    

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  • SUN Xidong, LI Xiliang
    Acta Mathematicae Applicatae Sinica. 2026, 49(5): 911-924. https://doi.org/10.20142/j.cnki.amas.202501049
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    In this paper,we study some properties of stochastic integral on isolated time scales,further prove that mean square bounded solutions to the linear stochastic dynamic equation can guarantee the existence of stochastic periodic solutions on isolated time scales.A sufficient condition is given for the existence of stochastic periodic solutions to the nonlinear stochastic dynamic equation on isolated time scales.
  • LIU Yonghui, DU Zhenyang, LIU Shuangzhe
    Acta Mathematicae Applicatae Sinica. 2026, 49(5): 925-943. https://doi.org/10.20142/j.cnki.amas.202600046
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    Matrix-valued time series are extensively utilized in economics,finance,industry and medicine due to their ability to continuously observe multiple locations and indicators.The matrix autoregressive(MAR) model offers a convenient framework for analyzing matrix-valued time series,featuring a clean bilinear structure and a manageable number of parameters.While theoretical advancements in parameter estimation and hypothesis testing for the MAR model have been thoroughly explored,statistical diagnostics for the model remain underdeveloped.In this paper,we address this gap by investigating the statistical diagnostics of matrix-valued time series autoregressive models.We apply Cook's local influence analysis method to derive diagnostic matrices for the curvature and slope of the MAR model under three types of perturbations:model perturbation,variance perturbation,and data perturbation.Numerical simulations are conducted to validate the proposed method,and empirical analyses confirm its practical applicability.
  • YANG Jiaopeng
    Acta Mathematicae Applicatae Sinica. 2026, 49(5): 944-968. https://doi.org/10.20142/j.cnki.amas.202501048
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    This paper investigates the Lyapunov stability of non-isolated and nonhyperbolic singular points in the generalized Jerk system under two critical scenarios:systems with infinitely many equilibrium points and those with no equilibrium points.Through theoretical analysis,we rigorously characterize the complex dynamical mechanisms underlying such system,including infinitely many periodic orbits,homoclinic orbits,and heteroclinic orbits;singular degenerate heteroclinic loops;and weak Li-Yorke chaos.Employing averaging theory,we provide a rigorous proof for the existence of hidden periodic orbits in the Jerk system without equilibrium points and elucidate their generation mechanism.Furthermore,numerical simulations via Lyapunov exponent spectra and bifurcation diagrams confirm the existence of hidden chaotic attractors and hidden tori.
  • ZHANG Fuchen, ZHANG Hong, XIAO Min
    Acta Mathematicae Applicatae Sinica. 2026, 49(5): 969-985. https://doi.org/10.20142/j.cnki.amas.202600025
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    This paper conducts an in-depth study on the nonlinear dynamic characteristics and synchronous control problems of a class of four-dimensional financial chaotic systems.Firstly,by introducing external factors such as market confidence,a new four-dimensional financial chaos model was constructed to analyze the dissipative property,equilibrium point stability and chaotic attractor characteristics of the system.Based on the Lyapunov exponent and Kaplan-Yorke dimension calculations,the hyperchaotic behavior of the system was verified.Secondly,two synchronous control strategies were proposed:1) Adaptive synchronous control based on the parameter adaptive law.By constructing a quadratic Lyapunov function,the global exponential stability of the error system was proved;2) Sliding mode synchronous control:The sliding mode manifold is designed by using the projection matrix,and the precise synchronization of the driver-response system is achieved in combination with the symbolic function controller.The numerical simulation results show that both control methods can effectively suppress chaotic oscillations.Among them,the adaptive control is robust to parameter uncertainties,while the sliding mode control exhibits stronger anti-interference ability.This research provides theoretical basis and methodological support for the stability analysis and risk control of the financial system.
  • ZHANG Qian
    Acta Mathematicae Applicatae Sinica. 2026, 49(5): 986-1003. https://doi.org/10.20142/j.cnki.amas.202600032
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    In this paper,the Hopf bifurcation of a diffusive predator-prey system with fear factors and defense mechanism are considered.Firstly,the local asymptotically stability of the non-negative equilibria are given.Secondly,by choosing the predator's natural growth rate as a bifurcation parameter,we investigate the conditions of the existence of the Hopf bifurcation.Next we give the Hopf bifurcation direction of diffusive system and the conditions for the stability of periodic solutions by using the center manifold theory and the normal form method.The results show that,self-diffusion does not produce Turing instability in the classical sense.Finally,some numerical simulations are presented to verify and supplement theoretical results.
  • SHI Zhanwen, JIN Shaojia
    Acta Mathematicae Applicatae Sinica. 2026, 49(5): 1004-1028. https://doi.org/10.20142/j.cnki.amas.202600062
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    The generalized case-cohort (GCC) Sampling design is widely used in large cohort studies to reduce costs associated with covariate measurement. Specifically, in many epidemiological studies where the incidence rate is moderate or high, the GCC design requires measuring covariate information for only a subset of cases, thereby reducing costs and saving time. In many such studies, the number of covariates is typically very large, thus requiring an effective variable selection method. This paper investigates the properties of variable selection methods using Smoothly Clipped Absolute Deviation (SCAD) penalization in the context of GCC designs with diverging parameters (i.e., the dimension of covariates $p_n$, whose growth rate is slower than $n^{1/4}$ as the sample size $n$ increases). We not only construct the corresponding penalized pseudo-partial likelihood estimator, but also prove the consistency and asymptotic normality of the proposed estimator. More importantly, this study demonstrates that the proposed method possesses the desirable asymptotic oracle property, meaning that it can accurately identify the truly important variables as if with prior knowledge of the true model structure. Finally, through extensive numerical simulations, we compare the finite-sample properties of the method using parameter tuning based on the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC), and summarize the more suitable methods under different scenarios. Finally, the proposed method is applied to the Wilms' tumor dataset for empirical analysis.
  • WANG Wei, FANG Cheng
    Acta Mathematicae Applicatae Sinica. 2026, 49(5): 1029-1052. https://doi.org/10.20142/j.cnki.amas.202501022
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    Schistosomiasis,as a waterborne infectious disease,sees the range of its vectors and hosts' habitats typically change periodically with variations in rainfall.In this paper,to investigate the impact of the periodic changes in river and lake areas on the transmission of schistosomiasis,a reaction-diffusion schistosomiasis model incorporating domain evolution was constructed.Initially,the model was transformed into a reaction-diffusion problem within a periodic environment.The basic reproduction number of the model was studied using spectral analysis and eigenvalue problems.Under this threshold condition,the long-term behavior of schistosomiasis transmission was explored under the assumption that the domain is periodically evolving.Numerical simulations and epidemiological interpretations further elucidated the impact of domain evolution on the spread of schistosomiasis.This work indicates that the periodic changes in the size of river and lake areas play a significant role in the transmission of schistosomiasis,particularly,an increase in the rate of domain evolution promotes the spread of schistosomiasis in river and lake regions.
  • CHEN Yang, ZHANG Liping, TIAN Maozai
    Acta Mathematicae Applicatae Sinica. 2026, 49(5): 1053-1074. https://doi.org/10.20142/j.cnki.amas.202600073
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    In reliability and survival analysis,censoring schemes have an important influence on both parameter estimation accuracy and experimental cost.This paper systematically studies parameter inference for the log-logistic distribution under the generalized progressive hybrid censoring(GPHC) scheme.An exact log-likelihood function is constructed,and the saddlepoint approximation(SPA) is introduced to develop the saddlepoint maximum likelihood estimator(SMLE).The formal 500-repetition Monte Carlo results show that SMLE and MLE have comparable point-estimation accuracy,indicating that the saddlepoint replacement does not introduce obvious first-order deviation.In the additional high-censoring scenarios,SMLE can be used as a high-order approximation supplement to the exact likelihood method;among them,SMLE-S has local improvement in the average interval length for the scale parameter α,with a positive-improvement rate of 83.95%.However,its interval performance depends on the specific design,and the sandwich covariance interval for the shape parameter may expand in a few extreme scenarios.The results clarify the applicability and limitations of SPA in inference for complex censored data.
  • ZHANG Yijin, MA Rui, LIN Zongbing
    Acta Mathematicae Applicatae Sinica. 2026, 49(5): 1075-1093. https://doi.org/10.20142/j.cnki.amas.202501025
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    High-dimensional data often contains a large number of redundant features,which significantly impact the efficiency of data mining and the generalization performance of machine learning algorithms.Dimensionality reduction is regarded as a crucial preprocessing step,which can enhance generalization performance and reduce computational costs.Feature selection is one of the predominant techniques for data dimensionality reduction.In this paper,we propose an unsupervised feature selection method based on hesitant fuzzy regularization and autoencoders.Firstly,two different projection methods are used to calculate the hesitant fuzzy correlation coefficient between features.Additionally,the absolute value of the Pearson correlation coefficient and the cosine correlation coefficient between features are computed.The correlation coefficient matrix of the features is then used to construct the regularization term.Secondly,the regularization term based on the correlation matrix is incorporated into the process of autoencoder feature selection to enhance the identification of redundant features.Finally,two different feature contribution measures are utilized to rank the features and select a subset of features.The objective function is optimized using back-propagation algorithm and proximal gradient descent method,and clustering and classification experiments are conducted over six representative datasets.The results of these experiments demonstrate the superiority of the proposed method.We also performs sensitivity analysis,stability analysis,and convergence analysis with the proposed method,showing its effectiveness.
  • LI Yongfeng, JIAO Caixia, SONG Xinyu
    Acta Mathematicae Applicatae Sinica. 2026, 49(5): 1094-1114. https://doi.org/10.20142/j.cnki.amas.202600071
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    In this paper,we propose a predator-prey model with state-dependent impulsive intervention,rotating two different measures for pest control.The implementation of control measures depends on both the population size of the pest and its rate of change.We discuss the maximum impulsive and phase sets of the system under four different cases.With the help of the Lambert W function,we construct a Poincaré map within phase space and discuss some of its properties,from which we derive the conditions for the stability of a periodic solution.By analyzing the one-parameter family of discrete maps,we determine sufficient conditions for the occurrence of the transcritical bifurcation.Finally,theoretical results are proved by numerical simulations.