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    Uncertainty Principles of Fractional Fourier Transform
    Zhou Yue, Yang Yan
    Acta mathematica scientia,Series A    2024, 44 (2): 257-264.  
    Abstract185)   HTML13)    PDF(pc) (564KB)(180)       Save

    Referring to the properties of Fourier transform, the authors find the uncertainty principle of discrete fractional Fourier transform and uncertainty principle of continuous fractional Fourier transform under Lebesgue measure, which makes the uncertainty principles of fractional Fourier transform more general.

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    Some Properties of Quasi-Periodic Functions and Their Applications
    Hu Keqi, Zhang Qingcai
    Acta mathematica scientia,Series A    2024, 44 (6): 1415-1425.  
    Abstract174)   HTML8)    PDF(pc) (560KB)(277)       Save

    In this paper, we estimate relevant properties of quasi-periodic functions, and these properties are applied. Under the additional condition, the conjecture proposed by Yang is solved.

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    Eigenvalues of a Class of Second-Order Differential Operator with Eigenparameters Dependent Internal Point Conditions
    Liu Wei, Xu Meizhen
    Acta mathematica scientia,Series A    2024, 44 (4): 815-828.  
    Abstract164)   HTML6)    PDF(pc) (535KB)(157)       Save

    This paper mainly discusses the self-adjointness and eigenvalue dependence of a class of second-order differential operator with internal point conditions containing an eigenparameter. First, a problem-related linear operator $T$ is defined in an appropriate Hilbert space, and the study of the problem to be transformed into the research of the operator $T$ in this space, and the operator $T$ is proved to be self-adjoint according to the definition of self-adjoint operator. In addition, on the basis of self-adjoint, it is proved that the eigenvalues are not only continuously dependent but also differentiable on each parameter of the problem, and the corresponding differential expressions are given. Meanwhile, the monotonicity of the eigenvalues with respect to the part parameters of the problem is also discussed.

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    Normalized Solutions of the Quasilinear Schrödinger System in Bounded Domains
    Qian Zhang
    Acta mathematica scientia,Series A    2025, 45 (1): 1-30.  
    Abstract164)   HTML5)    PDF(pc) (779KB)(196)       Save

    This paper is concerned with the following nonlinear coupled system
    $\left\{\begin{array}{l} -\Delta u_{1}+\omega_{1} u_{1}-\frac{1}{2} \Delta\left(u_{1}^{2}\right) u_{1}=\mu_{1}\left|u_{1}\right|^{p-1} u_{1}+\beta\left|u_{2}\right|^{\frac{p+1}{2}}\left|u_{1}\right|^{\frac{p-3}{2}} u_{1} \\ -\Delta u_{2}+\omega_{2} u_{2}-\frac{1}{2} \Delta\left(u_{2}^{2}\right) u_{2}=\mu_{2}\left|u_{2}\right|^{p-1} u_{2}+\beta\left|u_{1}\right|^{\frac{p+1}{2}}\left|u_{2}\right|^{\frac{p-3}{2}} u_{2} \\ \int_{\Omega}\left|u_{i}\right|^{2} \mathrm{~d} x=\rho_{i}, \quad i=1,2, \quad\left(u_{1}, u_{2}\right) \in H_{0}^{1}\left(\Omega ; \mathbb{R}^{2}\right) \end{array}\right.$
    and linear coupled system
    $\left\{\begin{array}{l} -\Delta u_{1}+\omega_{1} u_{1}-\frac{1}{2} \Delta\left(u_{1}^{2}\right) u_{1}=\mu_{1}\left|u_{1}\right|^{p-1} u_{1}+\beta u_{2} \\ -\Delta u_{2}+\omega_{2} u_{2}-\frac{1}{2} \Delta\left(u_{2}^{2}\right) u_{2}=\mu_{2}\left|u_{2}\right|^{p-1} u_{2}+\beta u_{1} \\ \int_{\Omega}\left|u_{i}\right|^{2} \mathrm{~d} x=\rho_{i}, \quad i=1,2, \quad\left(u_{1}, u_{2}\right) \in H_{0}^{1}\left(\Omega ; \mathbb{R}^{2}\right) \end{array}\right.$
    where $\Omega\subset\mathbb R^N(N\geq1)$ is a bounded smooth domain, $\omega_i,\ \beta\in\mathbb R$, $\mu_i,\ \rho_i>0,\ i=1,2.$ Moreover, $p>1$ if $N=1,2$ and $1<p\leqslant\frac{3N+2}{N-2}$ if $N\geqslant3$. Using change of variables, on the one hand, we prove the existence and stability of normalized solutions in nonlinear coupled system and the limiting behavior of normalized solutions as $\beta\rightarrow -\infty$. On the other hand, we apply the minimization constraint technique to obtain the existence of normalized solutions for linear coupled system. Compared with some previous results, we extend the existing results to the quasilinear Schrödinger system and also obtain normalized solutions for the linear coupling case.

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    Hankel Operators on Vector-Valued Bergman Space with Exponential Type Weights
    Dong Jianxiang
    Acta mathematica scientia,Series A    2024, 44 (3): 513-524.  
    Abstract161)   HTML15)    PDF(pc) (747KB)(174)       Save

    In this paper, we study some characterizations of Hankel operators on vector-valued exponential type weights Bergman spaces $A^{2}_{\varphi}(\mathcal{H})$ induced by operator-valued function symbols and co-analytic operator-valued function symbols. Main results including the boundedness and compactness of Hankel operators.

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    Properties and Computations of the $\mathfrak{m}$-WG Inverse
    Wei Huaquan, Wu Hui, Liu Xiaoji, Jin Hongwei
    Acta mathematica scientia,Series A    2024, 44 (3): 547-562.  
    Abstract135)   HTML1)    PDF(pc) (736KB)(225)       Save

    In this paper, the properties and computations of the $\mathfrak{m}$-WG inverse in Minskowski space are presented. Firstly, the characterization of the $\mathfrak{m}$-WG inverse is given by using the range and null space. Secondly, the relationship between the $\mathfrak{m}$-WG inverse and an invertible bordered matrix is given. Moreover, the perturbation bounds of the $\mathfrak{m}$-WG inverse is discussed. Finally, the successive matrix squaring algorithm is used to compute the $\mathfrak{m}$-WG inverse.

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    Multiplicity and Asymptotic Behavior of Normalized Solutions for Kirchhoff-Type Equation
    Jin Zhenfeng, Sun Hongrui, Zhang Weimin
    Acta mathematica scientia,Series A    2024, 44 (4): 871-884.  
    Abstract135)   HTML4)    PDF(pc) (619KB)(74)       Save

    In this paper, we consider the following Kirchhoff-type equation

    $\begin{cases} -\left(a+b\int_{\mathbb{R}^{3}}|\nabla u|^{2}\ d x\right)\Delta u=\lambda u+|u|^{p-2}u \quad \mathrm{in}\ \mathbb{R}^{3},\\ \|u\|^2_{2}=\rho,\end{cases}$

    where $a$, $b$, $\rho>0$ and $\lambda\in\mathbb{R}$ arises as Lagrange multiplier with respect to the mass constraint $\|u\|^2_{2}=\rho$. When $p\in\left(2,\frac{10}{3}\right)$ or $p\in\left(\frac{14}{3},6\right)$, we establish the existence of infinitely many radial $L^2$-normalized solutions by using the genus theory. Furthermore, we testify an asymptotic behavior of the above solutions with respect to the parameter $b\rightarrow 0^+$.

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    The Existence of Global Strong Solution to the Compressible Axisymmetric Navier-Stokes Equations with Density-Dependent Viscosities
    Gong Simeng, Zhang Xueyao, Guo Zhenhua
    Acta mathematica scientia,Series A    2024, 44 (6): 1445-1475.  
    Abstract122)   HTML2)    PDF(pc) (704KB)(105)       Save

    In this paper, we consider the compressible Navier-Stokes equations with viscous-dependent density in 3D space, and obtain a global axisymmetric strong solution with small energy and large initial oscillations in a periodic domain $\Omega=\{(r,z)\vert r=\sqrt{x^2+y^2},(x,y,z)\in\mathbb{R}^3,r\in I\subset(0,+\infty),z\in(-\infty,+\infty)\}$. When $z\rightarrow\pm\infty$, the initial density remains in a non-vacuum state. The results also show that as long as the initial density is far away from the vacuum, the solution will not develop the vacuum state in any time. And the exact decay rates of the solution is obtained.

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    Freely Quasiconformal Mappings in Quasiconvex Metric Spaces
    Chai Mengcen, Dai Yuxia
    Acta mathematica scientia,Series A    2024, 44 (5): 1127-1135.  
    Abstract113)   HTML12)    PDF(pc) (515KB)(159)       Save

    In this paper, we study freely quasiconformal mappings in quasiconvex metric spaces. It is proved that freely quasiconformal mappings and rough quasihyperbolic mappings in quasiconvex metric spaces are equivalent, and the quasisymmetric properties of freely quasiconformal mapping in quasiconvex metric spaces are obtained.

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    Existence of Some Special Conformally-K\"ahler metrics on Certain CP1 Bundles
    Acta mathematica scientia,Series A   
    Accepted: 15 November 2024

    Two-Weight Inequalities for $ {n}$-dimentional Hardy Operator and Commutators
    Wang Yaoyao, Lv Meichuan, Li Wenming
    Acta mathematica scientia,Series A    2024, 44 (3): 539-546.  
    Abstract106)   HTML7)    PDF(pc) (617KB)(98)       Save

    Let $ P $ be the Hardy operator on $ \mathbb{R}^n $ and $ Q $ be the adjoint operator. In this paper, we get the two-weight inequalities for $ P $, $ Q $ and the commutators of $ P $ and $ Q $ with $ CMO $ functions.

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    On Symmetry of the Product of Two Higher-Order Regular Quasi-Differential Operators
    Xiang Yanyu, Wang Aiping
    Acta mathematica scientia,Series A    2024, 44 (2): 265-275.  
    Abstract99)   HTML3)    PDF(pc) (553KB)(76)       Save

    The symmetric realizations of the product of two general regular quasi-differential expressions in Hilbert space are investigated. The two-point boundary conditions which determine symmetric operators are characterized and a sufficient and necessary condition for the product of two higher-order regular differential operators to be symmetric is obtained. The presented result contains the self-adjoint do-main characterization as a special case. Several examples of regular symmetric product operators are given.

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    The Adjoint Operator of Commutators
    Wang Xiaomin, Wu Deyu
    Acta mathematica scientia,Series A    2024, 44 (6): 1426-1432.  
    Abstract99)   HTML5)    PDF(pc) (469KB)(131)       Save

    In this paper, the adjoint operator problem of the commutators $[A, B] = AB-BA $ of two unbounded operators $A$ and $B$ is studied by the spectral theory and block operator matrix theory. The sufficient conditions for the relationship $[A,B]^*=(AB-BA)^*=B^*A^*-A^*B^*=-[A^*,B^*]$ hold are given. In the end, concrete examples is given to illustrate the effectiveness of criterions.

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    Study on Comprehensive Control Strategies of an Age Structured Influenza Model
    Yang Junyuan, Zhang Chenlin, Yang Li
    Acta mathematica scientia,Series A    2024, 44 (3): 804-814.  
    Abstract97)   HTML5)    PDF(pc) (9615KB)(112)       Save

    In this paper, we combine the age heterogeneity and the mechanisms of influenza to build an age structured SIR influenza model. Then we introduce two control variables-vaccination and treatment and propose the benefitial functional. Using the Pontryagin maximum principle and Ekland variant principle, we obtain the existence and uniqueness of the optimal control problem. Moreover, we employ forward and backward algorithms to do numerical experiments. Compared the results of many control measures, it is concluded that the combination of vaccination and treatment has the best control effect and furthermore, low-cost strategy is the best. Finally, through comprehensive analysis, vaccination has a best benefit from cost points of view and a combined measure has a best effect from public health perspectives.

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    The Product of Volterra Operator and Toeplitz Operator
    Ding Xuanhao, Shao Changhui, Li Yongning
    Acta mathematica scientia,Series A    2024, 44 (4): 829-836.  
    Abstract90)   HTML2)    PDF(pc) (539KB)(69)       Save

    In this paper, we study the product operators of Volterra operator $ V $ and Toeplitz operator $ T_\varphi $ on the classical Hardy space $ L_\varphi=T_\varphi V $ and $ R_\varphi=VT_\varphi $, and we obtain some basic properties of $ L_\varphi $ and $ R_\varphi $, we also get a result of $ L_\varphi $ which is similar to the Coburn theorem of Toeplitz operator. The necessary and sufficient conditions for $ V $ and $ T_\varphi $ to be commutative are given in this paper, and the symbol of $ L_\varphi $ and $ R_\varphi $ is characterized when $ z^jH^2\ (j=1, 2, \cdots ) $ are the common invariant subspaces of $ L_\varphi $ and $ R_\varphi $.

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    EC-tractability of Multivariate $\mathbb{L}_{\infty}$-approximation in Weighted Korobov Spaces
    Zhang Jie, Sun Yiming, Liu Yongping
    Acta mathematica scientia,Series A    2024, 44 (3): 525-538.  
    Abstract88)   HTML5)    PDF(pc) (797KB)(112)       Save

    In this paper we study exponential tractability of multivariate $\mathbb{L}_{\infty}$-approximation for weighted Korobov spaces in the worst case setting. We consider all algorithms that use the class $\Lambda^{\text{all}}$ of all linear functionals and the class $\Lambda^{\text{std}}$ of only function evaluations as information. We give matching necessary and sufficient conditions for notions of EC-quasi-polynomial tractability and EC-uniform weak tractability which have not been discussed before in terms of two weight parameters of the problem.

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    Solving the Forward and Inverse Problems of Extended Fifth-Order mKdV Equation Via Physics-Informed Neural Networks
    Wu Zekang, Wang Xiaoli, Han Wenjing, Li Jinhong
    Acta mathematica scientia,Series A    2024, 44 (2): 484-499.  
    Abstract87)   HTML2)    PDF(pc) (3075KB)(121)       Save

    With the help of the physics-informed neural networks (PINNs), the forward and inverse problems of extended fifth-order mKdV(emKdV) equation are tackled, and the dynamic behaviors of solitons are also analyzed and simulated in this paper. The hyperbolic tangent function $\tanh$ is selected as the activation function to solve the one, two and three-soliton solutions of the equation. Moreover, the data-driven solutions obtained by PINNs method are compared with the exact solution given by the simplified Hirota method. Specifically, the accuracy of one-soliton solution is $\mathcal{O}(10^{-4})$, and the accuracy of the two-soliton and three-soliton solutions is $\mathcal{O}(10^{-3})$. For the inverse problem, the coefficients of the equation are discovered by the data of one, two and three-soliton solutions, respectively. Meanwhile, the robustness of the PINNs algorithm is explored under different noises. The accuracy of the data-driven coefficients can reach $\mathcal{O}(10^{-3})$ or $\mathcal{O}(10^{-2})$ respectively, when 1% initial noise or observation noise is added to the training data. And the prediction accuracy can still reach $\mathcal{O}(10^{-2})$ even if 3% initial noise or observation noise is added. According to the analysis of experimental data, the impact of observation noise on PINNs model is slightly greater than the initial noise.

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    Existence and Uniqueness of Solutions for Sub-Linear Heat Equations with Almost Periodic Coefficients
    Chenchen Ren, Sudan Yang
    Acta mathematica scientia,Series A    2025, 45 (1): 31-43.  
    Abstract86)   HTML2)    PDF(pc) (558KB)(101)       Save

    In nature, almost periodic functions are "much more" than periodic functions, and an influential generalization of almost periodic functions is the asymptotic almost periodic function proposed by the famous mathematician M Fréchet in the study of almost periodic motions with perturbations. Thanks to this perturbative term, asymptotically almost periodic functions have a wider range of applications. In this paper, we study the existence and uniqueness of asymptotically almost periodic solutions of sub-linear heat equations with asymptotically almost periodic coefficients.

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    Numerical Range of the Complex Volterra Operator on Hardy Hilbert Space
    Wang Panxing, Liang Yuxia, Pang Songyue
    Acta mathematica scientia,Series A    2024, 44 (2): 276-285.  
    Abstract85)   HTML5)    PDF(pc) (563KB)(84)       Save

    The investigation on the numerical range of the complex Volterra operator on Hardy Hilbert space has always been a hot topic for mathematicians, which has not been solved. In this paper, we present the formulas for the numerical radius of an unilateral weighted shift operator with weights $ (h, k, j, b, a, b, a,\cdots ) $, where $ a, b, h, k, j> 0 $. In particular, we apply the above result to calculate the numerical range of the complex Volterra operator on Hardy Hilbert space. These results can not only effectively facilitate further study of the numerical ranges of weighted shift operators with disturbed periodic weights and harmonic weights, but also provide typical examples for the numerical range of bounded linear operators on Hardy Hilbert space.

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    Lyapunov-Type Inequalities for Dirichlet Problems of Multi-Term Caputo Fractional Differential Equations
    Zhang Wei, Chen Keyuan, Wu Yi, Ni Jinbo
    Acta mathematica scientia,Series A    2024, 44 (6): 1433-1444.  
    Abstract82)   HTML4)    PDF(pc) (542KB)(85)       Save

    This paper investigates the Lyapunov-type inequalities for a class of multi-term fractional differential equations with with a parameter, subject to Dirichlet boundary conditions. We first transform the fractional boundary value problem into an integral equation with Green's functions, then prove the relevant properties of the Green's functions, and finally obtain the corresponding Lyapunov-type inequalities using a priori estimation method. Multi-term fractional differential equations belong to the category of non-local equations, and their complexity exceeds that of single-term fractional differential equations. Studying the Lyapunov-type inequalities for multi-term fractional boundary value problems is of significant importance for the qualitative analysis of boundary value problems of multi-term fractional nonlinear differential equations.

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