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Efficient simulation of mixed boundary value problems and conformal mappings 混合边界值问题和保角映射的高效模拟
IF 3.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-10-24 DOI: 10.1016/j.amc.2024.129119
Qiansheng Han , Antti Rasila , Tommi Sottinen
We present a stochastic method for the simulation of Laplace's equation with a mixed boundary condition in planar domains that are polygonal or bounded by circular arcs. We call this method the Reflected Walk-on-Spheres algorithm. The method combines a traditional Walk-on-Spheres algorithm with use of reflections at the Neumann boundaries. We apply our algorithm to simulate numerical conformal mappings from certain quadrilaterals to the corresponding canonical domains, and to compute their conformal moduli. Finally, we give examples of the method on three dimensional polyhedral domains, and use it to simulate the heat flow on an L-shaped insulated polyhedron.
我们提出了一种在多边形或以圆弧为界的平面域中模拟具有混合边界条件的拉普拉斯方程的随机方法。我们称这种方法为反射随走随谢算法。该方法结合了传统的 "边走边球 "算法和诺伊曼边界反射算法。我们应用我们的算法来模拟从某些四边形到相应规范域的数值保角映射,并计算它们的保角模量。最后,我们举例说明了该方法在三维多面体域上的应用,并用它模拟了 L 型绝热多面体上的热流。
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引用次数: 0
Weighted Moore-Penrose inverses for dual matrices and its applications 对偶矩阵的加权摩尔-彭罗斯求逆及其应用
IF 3.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-10-24 DOI: 10.1016/j.amc.2024.129145
Haifeng Ma , Wen Wang , Predrag S. Stanimirović
Characteristics of weighted Moore-Penrose inverses for dual matrices (W-MP-D inverse) are studied in this investigation. First, we introduce the weighted compact dual singular value decomposition (WCDSVD) on the set of dual matrices. A few equivalent conditions for the existence of the W-MP-D inverse on the set of dual matrices and several explicit representations are given using WCDSVD. Finally, the simulation of standing waves (s-waves) and traveling waves (t-waves) and the application of that simulation in the t-waves identification in the brain are given.
本文研究了对偶矩阵的加权摩尔-彭罗斯逆(W-MP-D 逆)的特征。首先,我们介绍了对偶矩阵集合上的加权紧凑对偶奇异值分解(WCDSVD)。利用 WCDSVD 给出了对偶矩阵集合上 W-MP-D 逆存在的几个等价条件和几个显式表示。最后,给出了驻波(s 波)和行波(t 波)的模拟以及该模拟在大脑 t 波识别中的应用。
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引用次数: 0
A pseudo-Jacobi inverse eigenvalue problem with a rank-one modification 具有秩一修正的伪雅可比逆特征值问题
IF 3.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-10-21 DOI: 10.1016/j.amc.2024.129118
Wei-Ru Xu , Qian-Yu Shu , Natália Bebiano
Let H=diag(δ1,δ2,,δn) be a signature matrix, where δk{1,+1}. Consider Rn endowed with the indefinite inner product x,yH:=Hx,y=yTHx for all x,yRn. A pseudo-Jacobi matrix of order n is a real tridiagonal symmetric matrix with respect to this indefinite inner product. In this paper, the reconstruction of a pair of n-by-n pseudo-Jacobi matrices, one obtained from the other by a rank-one modification, is investigated given their prescribed spectra. Necessary and sufficient conditions under which this problem has a solution are presented. As a special case of the obtained results, a related problem for Jacobi matrices proposed by de Boor and Golub is thoroughly solved.
设 H=diag(δ1,δ2,...,δn)为签名矩阵,其中δk∈{-1,+1}。对于所有 x,y∈Rn,考虑 Rn 的不定内积 〈x,y〉H:=〈Hx,y〉=yTHx。n 阶伪雅可比矩阵是关于该不定内积的实三对角对称矩阵。本文研究了一对 n-by-n 伪雅可比矩阵的重构问题,其中一个矩阵是通过秩一修正从另一个矩阵得到的,并给出了它们的规定谱。本文提出了解决这一问题的必要条件和充分条件。作为所获结果的一个特例,de Boor 和 Golub 提出的雅可比矩阵的相关问题也得到了彻底解决。
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引用次数: 0
Mathematical models and numerical methods for a capital valuation adjustment (KVA) problem 资本估值调整 (KVA) 问题的数学模型和数值方法
IF 3.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-10-21 DOI: 10.1016/j.amc.2024.129105
Davide Trevisani, José Germán López-Salas, Carlos Vázquez, José Antonio García-Rodríguez
In this work we rigorously establish mathematical models to obtain the capital valuation adjustment (KVA) as part of the total valuation adjustments (XVAs). For this purpose, we use a semi-replication strategy based on market theory. We formulate single-factor models in terms of expectations and PDEs. For PDEs formulation, we rigorously obtain the existence and uniqueness of the solution, as well as some regularity and qualitative properties of the solution. Moreover, appropriate numerical methods are proposed for solving the corresponding PDEs. Finally, some examples show the numerical results for call and put European options and the corresponding XVA that includes the KVA.
在这项工作中,我们严格地建立了数学模型,以获得作为总估值调整(XVAs)一部分的资本估值调整(KVA)。为此,我们采用了基于市场理论的半复制策略。我们用预期和 PDEs 来制定单因素模型。对于 PDEs 的表述,我们严格获得了解的存在性和唯一性,以及解的一些规律性和定性属性。此外,我们还提出了求解相应 PDE 的适当数值方法。最后,一些实例展示了看涨和看跌欧式期权的数值结果,以及包括 KVA 的相应 XVA。
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引用次数: 0
Discrete-time event-triggered H-infinity stabilization for three closed-loop cyber-physical system with uncertain delay 具有不确定延迟的三闭环网络物理系统的离散时间事件触发 H-infinity 稳定化
IF 3.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-10-21 DOI: 10.1016/j.amc.2024.129127
Zhaoping Du, Chi Zhang, Xiaofei Yang, Hui Ye, Jianzhen Li
This paper investigates the problems of modeling and H∞ control for discrete three closed-loop cyber-physical system (CPS) with network delay, disturbance, and event-triggered control for the first time. A new even-triggered scheme is designed by incorporating a disturbance term, which reduces the number of triggers compared with some previous ones due to the inclusion of disturbance, and leads to the expansion of the triggered intervals. First, a new model of the system is constructed. Then, to provide sufficient conditions of the stability for the system with H∞ control, Lyapunov function and linear matrix inequality (LMI) techniques are used. Furthermore, the co-design method of three controllers and event-triggered matrix is proposed. Finally, the feasibility and practicality of the method proposed in this paper are verified by a simulation example of a marine boiler power generation control system. This kind of three closed-loop CPS model is constructed for the first time, which has been applied in different control systems such as servo motors, thermal power generation, etc.
本文首次研究了具有网络延迟、干扰和事件触发控制的离散三闭环网络物理系统(CPS)的建模和 H∞ 控制问题。通过加入扰动项,设计了一种新的偶数触发方案,与之前的一些方案相比,由于加入了扰动项,减少了触发次数,并扩大了触发间隔。首先,构建一个新的系统模型。然后,使用 Lyapunov 函数和线性矩阵不等式(LMI)技术为具有 H∞ 控制的系统提供稳定性的充分条件。此外,还提出了三个控制器和事件触发矩阵的协同设计方法。最后,通过船用锅炉发电控制系统的仿真实例验证了本文所提方法的可行性和实用性。本文首次构建了这种三闭环 CPS 模型,并将其应用于伺服电机、火力发电等不同的控制系统中。
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引用次数: 0
Two-relaxation-time regularized lattice Boltzmann model for convection-diffusion equation with spatially dependent coefficients 具有空间相关系数的对流扩散方程的双松弛时间正则化晶格玻尔兹曼模型
IF 3.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-10-21 DOI: 10.1016/j.amc.2024.129135
Yuan Yu , Zuojian Qin , Haizhuan Yuan , Shi Shu
In this paper, a new two-relaxation-time regularized (TRT-R) lattice Boltzmann (LB) model for the convection-diffusion equation (CDE) with spatially dependent coefficients is proposed. Within this framework, we first derive a TRT-R collision operator (CO) by constructing a new regularized procedure through the high-order Hermite expansion of non-equilibrium part. Then, a first-order discrete-velocity form of discrete source term is introduced to improve the accuracy of the source term. Finally, a new first-order space-derivative auxiliary term is proposed to recover the correct CDE. To assess this model, we simulated non-homogeneous convection-diffusion problems with adjustable diffusion intensity in both two and three dimensions. The findings indicate that the newly introduced source terms markedly enhance the model's precision and stability under varying time steps, grid resolutions, diffusion scaling coefficients, and magic parameters. The adoption of the TRT-R CO leads to a significant error reduction compared to the classic BGK CO in most scenarios. Furthermore, the influence of the magic parameter on the performance of the TRT-R CO was investigated. Beyond this, the study also confirms the efficacy of the TRT-R CO in eliminating numerical slip when enforcing Dirichlet boundary conditions with a halfway bounce-back scheme, thereby providing further evidence of the algorithm's advantages.
本文为具有空间依赖系数的对流扩散方程(CDE)提出了一种新的双松弛-时间正则化(TRT-R)晶格玻尔兹曼(LB)模型。在此框架内,我们首先通过对非平衡态部分进行高阶赫米特展开,构建一个新的正则化程序,从而推导出 TRT-R 碰撞算子(CO)。然后,引入离散源项的一阶离散速度形式,以提高源项的精度。最后,我们提出了一个新的一阶空间衍生辅助项来恢复正确的 CDE。为了评估这一模型,我们模拟了扩散强度可调的二维和三维非均质对流扩散问题。研究结果表明,在不同的时间步长、网格分辨率、扩散比例系数和魔法参数条件下,新引入的源项明显提高了模型的精度和稳定性。与传统的 BGK CO 相比,在大多数情况下,采用 TRT-R CO 可显著减少误差。此外,还研究了魔法参数对 TRT-R CO 性能的影响。除此以外,研究还证实了 TRT-R CO 在使用半程反弹方案强制执行 Dirichlet 边界条件时消除数值滑移的功效,从而进一步证明了该算法的优势。
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引用次数: 0
A step function based recursion method for 0/1 deep neural networks 基于阶跃函数的 0/1 深度神经网络递归方法
IF 3.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-10-21 DOI: 10.1016/j.amc.2024.129129
Hui Zhang , Shenglong Zhou , Geoffrey Ye Li , Naihua Xiu , Yiju Wang
The deep neural network with step function activation (0/1 DNNs) is a fundamental composite model in deep learning which has high efficiency and robustness to outliers. However, due to the discontinuity and lacking subgradient information of the 0/1 DNNs model, prior researches are largely focused on designing continuous functions to approximate the step activation and developing continuous optimization methods. In this paper, by introducing two sets of network node variables into the 0/1 DNNs and by exploring the composite structure of the resulted model, the 0/1 DNNs is decomposed into a unary optimization model associated with the step function and three derivational optimization subproblems associated with the other variables. For the unary optimization model and two derivational optimization subproblems, we present a closed form solution, and for the third derivational optimization subproblem, we propose an efficient proximal method. Based on this, a globally convergent step function based recursion method for the 0/1 DNNs is developed. The efficiency and performance of the proposed algorithm are validated via theoretical analysis as well as some illustrative numerical examples on classifying MNIST, FashionMNIST and Cifar10 datasets.
带阶跃函数激活的深度神经网络(0/1 DNNs)是深度学习中的一种基本复合模型,具有高效率和对异常值的鲁棒性。然而,由于 0/1 DNNs 模型的不连续性和缺乏子梯度信息,之前的研究主要集中在设计近似阶跃激活的连续函数和开发连续优化方法上。本文通过在 0/1 DNNs 中引入两组网络节点变量,并通过探索所得模型的复合结构,将 0/1 DNNs 分解为与阶跃函数相关的一元优化模型和与其他变量相关的三个衍生优化子问题。对于一元优化模型和两个派生优化子问题,我们提出了闭式解法;对于第三个派生优化子问题,我们提出了一种高效的近似方法。在此基础上,我们为 0/1 DNN 开发了一种基于阶跃函数的全局收敛递归方法。通过理论分析以及在 MNIST、FashionMNIST 和 Cifar10 数据集分类上的一些数值示例,验证了所提算法的效率和性能。
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引用次数: 0
Linear and nonlinear filtering for a two-layer quasi-geostrophic ocean model 双层准地养海洋模型的线性和非线性滤波
IF 3.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-10-21 DOI: 10.1016/j.amc.2024.129121
Lander Besabe , Michele Girfoglio , Annalisa Quaini , Gianluigi Rozza
Although the two-layer quasi-geostrophic equations (2QGE) are a simplified model for the dynamics of a stratified, wind-driven ocean, their numerical simulation is still plagued by the need for high resolution to capture the full spectrum of turbulent scales. Since such high resolution would lead to unreasonable computational times, it is typical to resort to coarse low-resolution meshes combined with the so-called eddy viscosity parameterization to account for the diffusion mechanisms that are not captured due to mesh under-resolution. We propose to enable the use of further coarsened meshes by adding a (linear or nonlinear) differential low-pass filter to the 2QGE, without changing the eddy viscosity coefficient. While the linear filter introduces constant (additional) artificial viscosity everywhere in the domain, the nonlinear filter relies on an indicator function to determine where and how much artificial viscosity is needed. Through several numerical results for a double-gyre wind forcing benchmark, we show that with the nonlinear filter we obtain accurate results with very coarse meshes, thereby drastically reducing the computational time (speed up ranging from 30 to 300).
尽管两层准地转方程(2QGE)是一个简化的分层风动海洋动力学模型,但其数值模拟仍然受到需要高分辨率以捕捉全部湍流尺度谱的困扰。由于这种高分辨率会导致不合理的计算时间,因此通常采用粗糙的低分辨率网格并结合所谓的涡粘参数化来解释由于网格分辨率不足而无法捕捉到的扩散机制。我们建议通过在 2QGE 中添加(线性或非线性)微分低通滤波器,在不改变涡粘系数的情况下使用进一步粗化的网格。线性滤波器在域内各处引入恒定(额外)的人工粘性,而非线性滤波器则依赖于一个指示函数来确定在何处以及需要多少人工粘性。通过几个双褶皱风力强迫基准的数值结果,我们表明,使用非线性滤波器,我们可以用非常粗的网格获得精确的结果,从而大大缩短计算时间(加速度从 30 到 300 不等)。
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引用次数: 0
Matrix expressions of symmetric n-player games 对称 n 人游戏的矩阵表达式
IF 3.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-10-17 DOI: 10.1016/j.amc.2024.129134
Yuanhua Wang , Ying Wang , Haitao Li , Wenke Zang
The symmetric property in n-player games is explored in this paper. First of all, some algebraically verifiable conditions are provided respectively for the totally symmetric, weakly symmetric and anonymous games, which are based on the construction of permutation matrix, and some interesting properties are revealed. Then we investigate how network structures affect the symmetry in a networked game. Some sufficient conditions are proposed and several nice properties are preserved when traditional networked games are extended to generalized networked games, in which the resulting network structure is more complex than a classical network graph.
本文探讨了 n 人博弈中的对称属性。首先,本文基于排列矩阵的构造,分别为完全对称博弈、弱对称博弈和匿名博弈提供了一些可验证的代数条件,并揭示了一些有趣的性质。然后,我们研究了网络结构如何影响网络博弈的对称性。当传统网络博弈扩展到广义网络博弈时,我们提出了一些充分条件,并保留了一些很好的性质,在广义网络博弈中,所产生的网络结构比经典网络图更复杂。
{"title":"Matrix expressions of symmetric n-player games","authors":"Yuanhua Wang ,&nbsp;Ying Wang ,&nbsp;Haitao Li ,&nbsp;Wenke Zang","doi":"10.1016/j.amc.2024.129134","DOIUrl":"10.1016/j.amc.2024.129134","url":null,"abstract":"<div><div>The symmetric property in <em>n</em>-player games is explored in this paper. First of all, some algebraically verifiable conditions are provided respectively for the totally symmetric, weakly symmetric and anonymous games, which are based on the construction of permutation matrix, and some interesting properties are revealed. Then we investigate how network structures affect the symmetry in a networked game. Some sufficient conditions are proposed and several nice properties are preserved when traditional networked games are extended to generalized networked games, in which the resulting network structure is more complex than a classical network graph.</div></div>","PeriodicalId":55496,"journal":{"name":"Applied Mathematics and Computation","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142445334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Mutual-visibility and general position in double graphs and in Mycielskians 双图和迈锡尔图中的互见性和一般位置
IF 3.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-10-17 DOI: 10.1016/j.amc.2024.129131
Dhanya Roy , Sandi Klavžar , Aparna Lakshmanan S
The general position problem in graphs is to find the largest possible set of vertices with the property that no three of them lie on a common shortest path. The mutual-visibility problem in graphs is to find the maximum number of vertices that can be selected such that every pair of vertices in the collection has a shortest path between them with no vertex from the collection as an internal vertex. Here, the general position problem and the mutual-visibility problem are investigated in double graphs and in Mycielskian graphs. Sharp general bounds are proved, in particular involving the total and the outer mutual-visibility number of base graphs. Several exact values are also determined, in particular the mutual-visibility number of the double graphs and of the Mycielskian of cycles.
图中的一般位置问题是找到最大可能的顶点集合,其性质是其中没有三个顶点位于共同的最短路径上。图中的互见性问题是找到可以选择的最大顶点数,使得集合中的每对顶点之间都有一条最短路径,且集合中没有顶点作为内部顶点。这里研究的是双图和迈锡尔图中的一般位置问题和互见性问题。证明了尖锐的一般界限,特别是涉及基图的总互见数和外互见数。此外,还确定了几个精确值,特别是双图和循环 Mycielskian 的互见数。
{"title":"Mutual-visibility and general position in double graphs and in Mycielskians","authors":"Dhanya Roy ,&nbsp;Sandi Klavžar ,&nbsp;Aparna Lakshmanan S","doi":"10.1016/j.amc.2024.129131","DOIUrl":"10.1016/j.amc.2024.129131","url":null,"abstract":"<div><div>The general position problem in graphs is to find the largest possible set of vertices with the property that no three of them lie on a common shortest path. The mutual-visibility problem in graphs is to find the maximum number of vertices that can be selected such that every pair of vertices in the collection has a shortest path between them with no vertex from the collection as an internal vertex. Here, the general position problem and the mutual-visibility problem are investigated in double graphs and in Mycielskian graphs. Sharp general bounds are proved, in particular involving the total and the outer mutual-visibility number of base graphs. Several exact values are also determined, in particular the mutual-visibility number of the double graphs and of the Mycielskian of cycles.</div></div>","PeriodicalId":55496,"journal":{"name":"Applied Mathematics and Computation","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142445335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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Applied Mathematics and Computation
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