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The numerical solution of a Fredholm integral equation of the second kind using the Galerkin method based on optimal interpolation 基于最优插值的伽辽金方法数值解第二类Fredholm积分方程
IF 1.4 Q2 MATHEMATICS, APPLIED Pub Date : 2025-06-23 DOI: 10.1016/j.rinam.2025.100607
Samandar Babaev , Abdullo Hayotov , Asliddin Boltaev , Surayyo Mirzoyeva , Malika Mirzaeva
In this paper, we study the Galerkin method for obtaining approximate solutions to linear Fredholm integral equations of the second kind. The finite element solution is represented as a linear combination of basis functions, and the construction of suitable basis functions plays a crucial role in the accuracy of the approximation. We propose an optimal interpolation formula that exactly reproduces the functions ex and ex, and derive basis functions from its coefficients. This interpolation formula is constructed within the Hilbert space W2(1,0). To evaluate the effectiveness of the proposed approach, we solve several integral equations using the Galerkin method with two types of basis functions: the newly constructed exponential basis and classical piecewise linear basis functions. Numerical experiments are presented to compare the accuracy of these approaches. Graphs and tables illustrate the approximation errors, demonstrating that both basis functions achieve an error order of O(h), with the optimal interpolation-based basis yielding superior accuracy in certain cases.
本文研究了求解第二类线性Fredholm积分方程近似解的Galerkin方法。有限元解被表示为基函数的线性组合,合适基函数的构造对逼近的精度起着至关重要的作用。我们提出了一个最优插值公式,精确地再现了函数ex和e - x,并从其系数推导出基函数。该插值公式在Hilbert空间W2(1,0)内构造。为了验证该方法的有效性,我们使用Galerkin方法求解了若干积分方程,并分别使用了两类基函数:新构造的指数基和经典的分段线性基函数。数值实验比较了这些方法的精度。图和表说明了近似误差,表明这两个基函数的误差阶为0 (h),在某些情况下,基于插值的最优基函数产生了更高的精度。
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引用次数: 0
TreeEM: Tree-enhanced ensemble model combining with feature selection for cancer subtype classification and survival prediction TreeEM:结合特征选择的树增强集成模型用于癌症亚型分类和生存预测
IF 1.4 Q2 MATHEMATICS, APPLIED Pub Date : 2025-06-20 DOI: 10.1016/j.rinam.2025.100605
Guoqiang Zhao, Dongxi Li
Cancer subtype analysis faces challenges due to limited availability of gene samples and the complexity of cancer gene expression data. The imbalance of Positive and negative category ratio and high-dimensional redundant information degrade prediction performance. This paper proposes an integrated extreme random forest with feature selection model TreeEM(Tree-enhanced Ensemble Model combining with feature selection) to enhance prediction ability and reduce computational costs. The TreeEM model combines the Max-Relevance and Min-Redundancy(MRMR) feature selection method with improved fusion undersampling random forest and extreme tree forest. The TreeEM model achieves excellent performance on three cancer datasets, especially on the multi-omics datasets BRCA(Breast Cancer) and ARCENE datasets, with average improvements of 7.90% and 1.90% in prediction accuracy, respectively. This model also uses TCGA data with known survival time for survival analysis and prediction, demonstrating the reliability of the TreeEM model. This work contributes to advancements in computational tools for cancer research, facilitating precision medicine approaches and improving decision-making. The above results provide new ideas for cancer subtype classification, but the existing methods still have limitations in data imbalance and high-dimensional feature processing. In the following section, the shortcomings of the current research and the innovative solutions of this paper are systematically described.
由于基因样本的有限可用性和癌症基因表达数据的复杂性,癌症亚型分析面临挑战。正负类比失衡和高维冗余信息会降低预测性能。为了提高预测能力和降低计算成本,本文提出了一种带有特征选择模型TreeEM(Tree-enhanced Ensemble model and feature selection)的集成极端随机森林模型。该模型将最大相关和最小冗余(MRMR)特征选择方法与改进的融合欠采样随机森林和极端树森林相结合。TreeEM模型在三个癌症数据集上取得了优异的表现,特别是在多组学数据集BRCA(Breast cancer)和ARCENE数据集上,预测准确率平均分别提高了7.90%和1.90%。该模型还使用已知生存时间的TCGA数据进行生存分析和预测,证明了TreeEM模型的可靠性。这项工作有助于癌症研究的计算工具的进步,促进精准医学方法和改进决策。上述结果为癌症亚型分类提供了新的思路,但现有方法在数据不平衡、高维特征处理等方面仍存在局限性。在接下来的部分中,系统地描述了当前研究的不足和本文的创新解决方案。
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引用次数: 0
Global boundedness of a three-species spatial intraguild predation model with alarm-taxis 具有报警趋向性的三种空间捕食模型的全局有界性
IF 1.4 Q2 MATHEMATICS, APPLIED Pub Date : 2025-06-18 DOI: 10.1016/j.rinam.2025.100602
Pengfei Luo , Yun Zhang , Lu Xu
The directional motivation of predator is influenced by the density of prey and its alarm call, this paper focuses on a three-species spatial intraguild predation model involving prey-taxis and alarm-taxis. By energy estimates and heat semigroup theory, we prove that this model possesses a bounded and global classical solution in N-dimensional space (N3) with Neumann boundary conditions.
捕食者的定向动机受猎物密度及其报警信号的影响,本文研究了一个包含趋向性和报警趋向性的三物种空间捕食模型。利用能量估计和热半群理论,证明了该模型在N维空间(N≥3)具有Neumann边界条件的有界全局经典解。
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引用次数: 0
Analytical computation of five unresolved integrals in the linear theory of partially cavitating hydrofoils 部分空化水翼线性理论中五个未解析积分的解析计算
IF 1.4 Q2 MATHEMATICS, APPLIED Pub Date : 2025-06-16 DOI: 10.1016/j.rinam.2025.100599
Jean-Baptiste Leroux, Matthieu Sacher
Five non-tabulated integrals are analytically calculated. These integrals emerge from the linear theory of partially cavitating hydrofoils and propeller blades. They appear in a series of weight functions involved in the determination of the cavitation number and cavity shape. The present analytical results eliminate the need for unnecessary numerical integrations, which could be beneficial in reducing computational costs and improving the robustness of numerical models.
分析计算了五个非表积分。这些积分来自部分空化水翼和螺旋桨叶片的线性理论。它们出现在确定空化数和空腔形状所涉及的一系列权函数中。本文的分析结果消除了不必要的数值积分,这有利于降低计算成本和提高数值模型的鲁棒性。
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引用次数: 0
A kind of adaptive variable stepsize embedded Runge–Kutta pairs coupled with the Sinc collocation method for solving the KdV equation 一种自适应变步长嵌入龙格-库塔对并结合Sinc配置法求解KdV方程
IF 1.4 Q2 MATHEMATICS, APPLIED Pub Date : 2025-06-16 DOI: 10.1016/j.rinam.2025.100604
Cheng Chen , Wenting Shao
For solving the KdV equation, a novel numerical method with high order accuracy in both space and time is proposed. In the spatial direction, Sinc collocation method, which has the property of exponential convergence, is adopted. In the temporal direction, the variable stepsize Runge–Kutta-embedded pair RKq(p) is utilized. Sinc collocation method is applicable when the approximated function satisfies the exponential decay as the spatial variable tends to infinity, this characteristic is consistent with the one of the soliton solution of the KdV equation. For practical computation, a sufficiently large finite domain is taken, on which the differential matrices with respect to the discrete points are constructed. A new adaptive strategy is proposed to enhance the robustness of the variable stepsize algorithm. In the numerical experiment, four embedded pairs including RK5(4), RK6(5), RK8(7) and RK9(8) are investigated in terms of accuracy, CPU time, the minimum, average and maximum time stepsizes. The numerical results show that RK8(7) has a better performance in the computational efficiency, it achieves higher accuracy with significantly less CPU time. Besides, the KdV-Burgers equation with nonhomogeneous Dirichlet boundary condition imposed on a general interval is considered. The single-exponential transformation and double-exponential transformation are involved. We show that Sinc collocation method, enhanced by exponential transformations, provides an effective numerical approximation for this problem.
为了求解KdV方程,提出了一种在空间和时间上都具有高阶精度的数值方法。在空间方向上,采用具有指数收敛性的Sinc配置方法。在时间方向上,采用变步长龙格-库塔嵌入对RKq(p)。当空间变量趋于无穷时,近似函数满足指数衰减时,适用Sinc配点法,这一特性与KdV方程孤子解的特性一致。在实际计算中,取一个足够大的有限域,在这个有限域上构造关于离散点的微分矩阵。为了提高变步长算法的鲁棒性,提出了一种新的自适应策略。在数值实验中,研究了RK5(4)、RK6(5)、RK8(7)和RK9(8)四个嵌入式对的精度、CPU时间、最小、平均和最大时间步长。数值结果表明,RK8(7)在计算效率上具有更好的性能,在显著减少CPU时间的情况下实现了更高的精度。此外,还考虑了一般区间上具有非齐次Dirichlet边界条件的KdV-Burgers方程。涉及到单指数变换和双指数变换。我们证明了指数变换增强的Sinc配置方法为该问题提供了有效的数值近似。
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引用次数: 0
A numerical method based on the shifted Jacobi polynomials for a class of tempered fractional quadratic integro-differential equations 一类缓变分数阶二次积分微分方程的基于移位Jacobi多项式的数值解法
IF 1.4 Q2 MATHEMATICS, APPLIED Pub Date : 2025-06-13 DOI: 10.1016/j.rinam.2025.100601
P. Senfiazad , M.H. Heydari , M. Bayram , D. Baleanu
This paper introduces a new class of tempered fractional quadratic integro-differential equations using the Caputo fractional derivative. The existence and uniqueness of solutions to these equations are analyzed. A numerical method based on the shifted Jacobi polynomials is developed to solve these equations. To execute the proposed method, two operational matrices corresponding to the ordinary and Riemann–Liouville tempered fractional integrals of these polynomials are extracted. In the developed method, the tempered fractional derivative term is initially represented as a linear combination of the aforementioned polynomials with some unknown coefficients. Then, by applying the Riemann–Liouville tempered fractional integral to the expressed polynomials and utilizing their fractional integral operational matrix, an approximation of the unknown solution is defined based on these polynomials and the introduced coefficients. Subsequently, by substituting these approximations into the problem under consideration, and applying the operational matrix of ordinary integral to the shifted Jacobi polynomials, along with utilizing their orthogonality, an approximate solution to the original problem is obtained by solving a nonlinear system of algebraic equations. The convergence of the proposed method is analyzed theoretically and demonstrated through numerical examples. Furthermore, the stability of the solutions is analyzed.
本文利用Caputo分数阶导数引入了一类新的缓变分数阶二次积分微分方程。分析了这些方程解的存在唯一性。提出了一种基于移位雅可比多项式的数值求解方法。为了实现所提出的方法,提取了对应于这些多项式的普通积分和黎曼-刘维尔回火分数积分的两个运算矩阵。在所开发的方法中,缓和分数阶导数项最初表示为上述多项式与一些未知系数的线性组合。然后,将Riemann-Liouville调质分数阶积分应用于所表达的多项式,并利用其分数阶积分运算矩阵,基于这些多项式和引入的系数定义未知解的近似。随后,将这些近似代入所考虑的问题,并将普通积分的运算矩阵应用于移位的雅可比多项式,并利用它们的正交性,通过求解非线性代数方程组得到原问题的近似解。从理论上分析了该方法的收敛性,并通过数值算例进行了验证。进一步分析了解的稳定性。
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引用次数: 0
Convergence analysis of option drift rate inverse problem based on degenerate parabolic equation 基于退化抛物方程的期权漂移率反问题收敛性分析
IF 1.4 Q2 MATHEMATICS, APPLIED Pub Date : 2025-05-01 DOI: 10.1016/j.rinam.2025.100561
Miao-miao Song , Zui-cha Deng , Xiang Li , Qiu Cui
In this paper, we study the convergence of the inverse drift rate problem of option pricing based on degenerate parabolic equations, aiming to recover the stock price drift rate function by known option market prices. Unlike the classical inverse parabolic equation problem, the article transforms the original problem into an inverse problem with principal coefficients of the degenerate parabolic equation over a bounded region by variable substitution, thus avoiding the error introduced by artificial truncation. Under the optimal control framework, the problem is transformed into an optimization problem, the existence of the minimal solution is proved, and a mathematical proof of the convergence of the optimal solution is given. Finally, the gradient-type iterative method is applied to obtain the numerical solution of the inverse problem, and numerical experiments are conducted to verify it. This study provides an effective theoretical framework and numerical method for inferring the stock price drift rate from the option market price.
本文研究了基于退化抛物方程的期权定价逆漂移率问题的收敛性,旨在通过已知的期权市场价格恢复股票价格漂移率函数。与经典的反抛物方程问题不同,本文通过变量替换将原问题转化为退化抛物方程在有界区域上的主系数反问题,从而避免了人为截断带来的误差。在最优控制框架下,将该问题转化为优化问题,证明了最小解的存在性,并给出了最优解收敛性的数学证明。最后,采用梯度型迭代法得到了反问题的数值解,并进行了数值实验验证。本研究为从期权市场价格推断股票价格漂移率提供了有效的理论框架和数值方法。
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引用次数: 0
A condition for the finite time blow up of the incompressible Navier–Stokes equations in the whole space 全空间不可压缩Navier-Stokes方程有限时间爆破的条件
IF 1.4 Q2 MATHEMATICS, APPLIED Pub Date : 2025-05-01 DOI: 10.1016/j.rinam.2025.100590
Abdelhafid Younsi
This paper is interested in the existence of singularities for solutions of the Navier–Stokes equations in the whole space. We demonstrate the existence of initial data that leads to the unboundedness of the corresponding strong solution within a finite time. Our approach relies on lower and upper bounds of rates of decay for solutions to the Navier–Stokes equations. This result provides valuable insights into significant open problems in both physics and mathematics.
本文研究了Navier-Stokes方程解在整个空间中的奇异性。我们证明了初始数据的存在性,使得相应的强解在有限时间内无界。我们的方法依赖于Navier-Stokes方程解的衰减率的下界和上界。这一结果为物理学和数学中的重大开放问题提供了有价值的见解。
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引用次数: 0
Study of nonlinear anisotropic elliptic problems with non-local boundary conditions in weighted variable exponent Sobolev spaces 加权变指数Sobolev空间中具有非局部边界条件的非线性各向异性椭圆问题的研究
IF 1.4 Q2 MATHEMATICS, APPLIED Pub Date : 2025-05-01 DOI: 10.1016/j.rinam.2025.100597
Soumia EL OMARI, Said Melliani
This study investigates the existence of weak solutions for nonlinear anisotropic elliptic equations characterized by non-local boundary conditions within anisotropic weighted variable exponent Sobolev spaces. By employing variational methods and compact embedding theorems tailored to anisotropic Sobolev spaces, the research focuses on understanding the impact of anisotropy, non-locality, and weighted structures on the solution behavior. We establish sufficient conditions for the existence of solutions under various boundary conditions. These results deepen the understanding of anisotropic elliptic problems by highlighting the role of weighted structures and variable exponents in the interaction between anisotropy and non-locality. The study also explores non-local boundary conditions, which may include integrals of the unknown function over parts of the domain or non-local operators, often encountered in applications such as well modeling in 3D stratified petroleum reservoirs with arbitrary geometries. This work provides a solid theoretical foundation for broader applications in engineering and physics.
研究了各向异性加权变指数Sobolev空间中具有非局部边界条件的非线性各向异性椭圆方程弱解的存在性。利用各向异性Sobolev空间的变分方法和紧凑嵌入定理,重点研究了各向异性、非局域性和加权结构对解行为的影响。建立了在各种边界条件下解存在的充分条件。这些结果通过强调加权结构和变指数在各向异性和非局域性相互作用中的作用,加深了对各向异性椭圆问题的理解。该研究还探讨了非局部边界条件,其中可能包括部分区域上未知函数的积分或非局部算子,这些情况在任意几何形状的三维分层油藏的井建模等应用中经常遇到。这项工作为工程和物理的广泛应用提供了坚实的理论基础。
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引用次数: 0
The regression-based efficient frontier 基于回归的效率边界
IF 1.4 Q2 MATHEMATICS, APPLIED Pub Date : 2025-05-01 DOI: 10.1016/j.rinam.2025.100578
Wan-Yi Chiu
The standard mean–variance analysis employs quadratic optimization to determine the optimal portfolio weights and to plot the mean–variance efficient frontier (MVEF). It then indirectly evaluates the mean–variance efficiency test (MVET) by considering the maximum Sharpe ratios of the tangency portfolio within the MVEF framework, which assumes a risk-free rate. This paper integrates these procedures without considering the risk-free rate by transitioning to a regression-based efficient frontier (RBEF). The RBEF estimates the optimal portfolio weights and simultaneously implements the MVET based on an OLS F-test, offering a simpler approach to portfolio optimization.
标准均值-方差分析采用二次优化方法确定最优投资组合权重,并绘制均值-方差有效边界。然后,通过考虑MVEF框架内切线投资组合的最大夏普比率(假设无风险利率),间接评估均值方差效率检验(MVET)。本文通过过渡到基于回归的有效边界(RBEF)来整合这些过程,而不考虑无风险率。RBEF估计了最优投资组合权重,同时基于OLS f检验实现了MVET,为投资组合优化提供了一种更简单的方法。
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引用次数: 0
期刊
Results in Applied Mathematics
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