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A mixed operator approach to peridynamics 周动力学的混合算子方法
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2023-01-01 DOI: 10.3934/mine.2023082
F. Cluni, V. Gusella, Dimitri Mugnai, Edoardo Proietti Lippi, P. Pucci
In the present paper we propose a model describing the nonlocal behavior of an elastic body using a peridynamical approach. Indeed, peridynamics is a suitable framework for problems where discontinuities appear naturally, such as fractures, dislocations, or, in general, multiscale materials. In particular, the regional fractional Laplacian is used as the nonlocal operator. Moreover, a combination of the fractional and classical Laplacian operators is used to obtain a better description of the phenomenological response in elasticity. We consider models with linear and nonlinear perturbations. In the linear case, we prove the existence and uniqueness of the solution, while in the nonlinear case the existence of at least two nontrivial solutions of opposite sign is proved. The linear and nonlinear problems are also solved by a numerical approach which estimates the regional fractional Laplacian by means of its singular integral representation. In both cases, a numerical estimation of the solutions is obtained, using in the nonlinear case an approach involving a random variation of an initial guess of the solution. Moreover, in the linear case a parametric analysis is made in order to study the effects of the parameters involved in the model, such as the order of the fractional Laplacian and the mixture law between local and nonlocal behavior.
在本文中,我们提出了一个用周动力学方法描述弹性体非局部行为的模型。事实上,对于不连续自然出现的问题,如断裂、位错或一般的多尺度材料,周动力学是一个合适的框架。特别地,使用区域分数阶拉普拉斯算子作为非局部算子。此外,将分数算子与经典拉普拉斯算子结合使用,可以更好地描述弹性的现象学响应。我们考虑具有线性和非线性扰动的模型。在线性情况下,证明了解的存在唯一性,在非线性情况下,证明了至少两个对号非平凡解的存在性。利用区域分数阶拉普拉斯算子的奇异积分表示估计区域分数阶拉普拉斯算子的数值方法解决了线性和非线性问题。在这两种情况下,都得到了解的数值估计,在非线性情况下,使用一种涉及解的初始猜测的随机变化的方法。此外,在线性情况下进行了参数分析,以研究模型中涉及的参数的影响,如分数阶拉普拉斯阶和局部与非局部行为之间的混合律。
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引用次数: 0
Games associated with products of eigenvalues of the Hessian 与黑森特征值乘积相关的博弈
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2023-01-01 DOI: 10.3934/mine.2023066
P. Blanc, Fernando Charro, J. Manfredi, J. Rossi
We introduce games associated with second-order partial differential equations given by arbitrary products of eigenvalues of the Hessian. We prove that, as a parameter that controls the step length goes to zero, the value functions of the games converge uniformly to a viscosity solution of the partial differential equation. The classical Monge-Ampère equation is an important example under consideration.
我们引入了由Hessian特征值的任意乘积给出的二阶偏微分方程相关的对策。我们证明了当控制步长趋近于零的参数时,对策的值函数一致收敛于偏微分方程的黏性解。经典的monge - ampantere方程是一个重要的例子。
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引用次数: 1
Nanoparticle-based organic polymer retinal prostheses: modeling, solution map and simulation 基于纳米粒子的有机聚合物视网膜假体:建模、溶液图和仿真
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2023-01-01 DOI: 10.3934/mine.2023075
G. Chiaravalli, G. Lanzani, R. Sacco, S. Salsa
In this article we investigate a mathematical model for a retinal prosthesis made of organic polymer nanoparticles (NP) in the stationary regime. The model consists of a Drift-Diffusion system to describe free charge transport in the NP bulk; a Poisson-Nernst-Planck system to describe ion electrodiffusion in the solution surrounding the NP; and nonlinear transmission conditions at the NP-solution interface. To solve the model we use an iteration procedure for which we prove the existence and briefly comment the uniqueness of a fixed point under suitable smallness assumptions on model parameters. For system discretization we use a stabilized finite element method to prevent unphysical oscillations in the electric potential, carrier number densities and ion molar densities. Model predictions describe the amount of active chemical molecule accumulating at the neuron surface and highlight electrostatic effects induced by the sole presence of the nanoparticle. These results support the use of mathematical modeling as a virtual laboratory for the optimal design of bio-hybrid systems, whose investigation may be impervious due to experimental limits.
在本文中,我们研究了在固定状态下由有机聚合物纳米颗粒(NP)制成的视网膜假体的数学模型。该模型由一个漂移-扩散系统来描述NP块体中的自由电荷输运;用泊松-能斯特-普朗克体系描述NP周围溶液中的离子电扩散;和np -解界面处的非线性传输条件。为了求解该模型,我们采用迭代法证明了模型参数在适当的小假设下不动点的存在性,并简要说明了不动点的唯一性。对于系统离散,我们使用稳定有限元方法来防止电势、载流子数密度和离子摩尔密度的非物理振荡。模型预测描述了在神经元表面积累的活性化学分子的数量,并强调了纳米颗粒单独存在所引起的静电效应。这些结果支持使用数学建模作为生物混合系统优化设计的虚拟实验室,其研究可能由于实验限制而无法渗透。
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引用次数: 0
Equilibrium of thin shells under large strains without through-the-thickness shear and self-penetration of matter 大应变下薄壳的平衡,无物质的穿厚剪切和自穿透
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2023-01-01 DOI: 10.3934/mine.2023092
P. M. Mariano, D. Mucci
We consider elastic thin shells without through-the-thickness shear and depict them as Gauss graphs of parametric surfaces. (We use the term shells to include plates and thin films therein.) We consider an energy depending on the first derivative of the Gauss map (so, it involves curvatures) and its second-rank minors. For it we prove existence of minimizers in terms of currents carried by Gauss graphs. In the limiting process we adopt sequences of competitors that satisfy a condition that prevents self-penetration of matter.
我们考虑无过厚剪切的弹性薄壳,并将其描述为参数曲面的高斯图。(我们使用“壳”一词来包括其中的板和薄膜。)我们考虑的能量依赖于高斯映射的一阶导数(因此,它涉及曲率)和它的二阶次导数。为此,我们用高斯图所载电流证明了极小值的存在性。在极限过程中,我们采用满足防止物质自我穿透的条件的竞争者序列。
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引用次数: 1
Polyconvex functionals and maximum principle 多凸泛函和极大原理
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2023-01-01 DOI: 10.3934/mine.2023077
M. Carozza, L. Esposito, Raffaella Giova, F. Leonetti

Let us consider continuous minimizers $ u : bar Omega subset mathbb{R}^n to mathbb{R}^n $ of

with $ p > 1 $ and $ r > 0 $; then it is known that every component $ u^alpha $ of $ u = (u^1, ..., u^n) $ enjoys maximum principle: the set of interior points $ x $, for which the value $ u^alpha(x) $ is greater than the supremum on the boundary, has null measure, that is, $ mathcal{L}^n({ x in Omega: u^alpha (x) > sup_{partial Omega} u^alpha }) = 0 $. If we change the structure of the functional, it might happen that the maximum principle fails, as in the case

with $ p > 1 $ and $ r > 0 $. Indeed, for a suitable boundary value, the set of the interior points $ x $, for which the value $ u^alpha(x) $ is greater than the supremum on the boundary, has a positive measure, that is $ mathcal{L}^n({ x in Omega: u^alpha (x) > sup_{partial Omega} u^alpha }) > 0 $. In this paper we show that the measure of the image of these bad points is zero, that is $ mathcal{L}^n(u({ x in Omega: u^alpha (x) > sup_{partial Omega} u^alpha })) = 0 $, provided $ p > n $. This is a particular case of a more general theorem.

Let us consider continuous minimizers $ u : bar Omega subset mathbb{R}^n to mathbb{R}^n $ of begin{document}$ mathcal{F}(v) = int_{Omega} [|Dv|^p , + , |{rm det},Dv|^r] dx, $end{document} with $ p > 1 $ and $ r > 0 $; then it is known that every component $ u^alpha $ of $ u = (u^1, ..., u^n) $ enjoys maximum principle: the set of interior points $ x $, for which the value $ u^alpha(x) $ is greater than the supremum on the boundary, has null measure, that is, $ mathcal{L}^n({ x in Omega: u^alpha (x) > sup_{partial Omega} u^alpha }) = 0 $. If we change the structure of the functional, it might happen that the maximum principle fails, as in the case begin{document}$ mathcal{F}(v) = int_{Omega}[max{(|Dv|^p - 1); 0 } , + , |{rm det},Dv|^r] dx, $end{document} with $ p > 1 $ and $ r > 0 $. Indeed, for a suitable boundary value, the set of the interior points $ x $, for which the value $ u^alpha(x) $ is greater than the supremum on the boundary, has a positive measure, that is $ mathcal{L}^n({ x in Omega: u^alpha (x) > sup_{partial Omega} u^alpha }) > 0 $. In this paper we show that the measure of the image of these bad points is zero, that is $ mathcal{L}^n(u({ x in Omega: u^alpha (x) > sup_{partial Omega} u^alpha })) = 0 $, provided $ p > n $. This is a particular case of a more general theorem.
{"title":"Polyconvex functionals and maximum principle","authors":"M. Carozza, L. Esposito, Raffaella Giova, F. Leonetti","doi":"10.3934/mine.2023077","DOIUrl":"https://doi.org/10.3934/mine.2023077","url":null,"abstract":"<abstract><p>Let us consider continuous minimizers $ u : bar Omega subset mathbb{R}^n to mathbb{R}^n $ of</p> <p><disp-formula> <label/> <tex-math id=\"FE1\"> begin{document}$ mathcal{F}(v) = int_{Omega} [|Dv|^p , + , |{rm det},Dv|^r] dx, $end{document} </tex-math></disp-formula></p> <p>with $ p > 1 $ and $ r > 0 $; then it is known that every component $ u^alpha $ of $ u = (u^1, ..., u^n) $ enjoys maximum principle: the set of interior points $ x $, for which the value $ u^alpha(x) $ is greater than the supremum on the boundary, has null measure, that is, $ mathcal{L}^n({ x in Omega: u^alpha (x) > sup_{partial Omega} u^alpha }) = 0 $. If we change the structure of the functional, it might happen that the maximum principle fails, as in the case</p> <p><disp-formula> <label/> <tex-math id=\"FE2\"> begin{document}$ mathcal{F}(v) = int_{Omega}[max{(|Dv|^p - 1); 0 } , + , |{rm det},Dv|^r] dx, $end{document} </tex-math></disp-formula></p> <p>with $ p > 1 $ and $ r > 0 $. Indeed, for a suitable boundary value, the set of the interior points $ x $, for which the value $ u^alpha(x) $ is greater than the supremum on the boundary, has a positive measure, that is $ mathcal{L}^n({ x in Omega: u^alpha (x) > sup_{partial Omega} u^alpha }) > 0 $. In this paper we show that the measure of the image of these bad points is zero, that is $ mathcal{L}^n(u({ x in Omega: u^alpha (x) > sup_{partial Omega} u^alpha })) = 0 $, provided $ p > n $. This is a particular case of a more general theorem.</p></abstract>","PeriodicalId":54213,"journal":{"name":"Mathematics in Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70225428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
A "nonlinear duality" approach to $ W_0^{1, 1} $ solutions in elliptic systems related to the Keller-Segel model Keller-Segel模型下椭圆系统$ W_0^{1,1} $解的“非线性对偶”方法
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2023-01-01 DOI: 10.3934/mine.2023085
L. Boccardo
In this paper, we prove existence of distributional solutions of a nonlinear elliptic system, related to the Keller-Segel model. Our starting point is the boundedness theorem (for solutions of elliptic equations) proved by Guido Stampacchia and Neil Trudinger.
本文证明了一类非线性椭圆型系统分布解的存在性,涉及到Keller-Segel模型。我们的出发点是Guido Stampacchia和Neil Trudinger证明的(椭圆方程解的)有界性定理。
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引用次数: 1
$ L^{p} $ compactness criteria with an application to variational convergence of some nonlocal energy functionals L^{p} $紧性准则及其在一些非局部能量泛函变分收敛中的应用
4区 工程技术 Q2 Mathematics Pub Date : 2023-01-01 DOI: 10.3934/mine.2023097
Qiang Du, Tadele Mengesha, Xiaochuan Tian

Motivated by some variational problems from a nonlocal model of mechanics, this work presents a set of sufficient conditions that guarantee a compact inclusion in the function space of $ L^{p} $ vector fields defined on a domain $ Omega $ that is either a bounded domain in $ mathbb{R}^{d} $ or $ mathbb{R}^{d} $ itself. The criteria are nonlocal and are given with respect to nonlocal interaction kernels that may not be necessarily radially symmetric. Moreover, these criteria for vector fields are also different from those given for scalar fields in that the conditions are based on nonlocal interactions involving only parts of the components of the vector fields. The $ L^{p} $ compactness criteria are utilized in demonstrating the convergence of minimizers of parameterized nonlocal energy functionals.

>< >& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;& gt;这些准则是非局部的,并且是关于非局部相互作用核给出的,这些核不一定是径向对称的。此外,这些向量场的准则也不同于标量场的准则,因为这些条件是基于只涉及向量场部分分量的非局部相互作用。$ L^{p} $紧性准则用于证明参数化非局部能量泛函的极小值的收敛性。</p></abstract>
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引用次数: 3
Layered solutions for a nonlocal Ginzburg-Landau model with periodic modulation 具有周期调制的非局部金兹堡-朗道模型的分层解
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2023-01-01 DOI: 10.3934/mine.2023090
Ko-Shin Chen, C. Muratov, Xiaodong Yan
We study layered solutions in a one-dimensional version of the scalar Ginzburg-Landau equation that involves a mixture of a second spatial derivative and a fractional half-derivative, together with a periodically modulated nonlinearity. This equation appears as the Euler-Lagrange equation of a suitably renormalized fractional Ginzburg-Landau energy with a double-well potential that is multiplied by a 1-periodically varying nonnegative factor $ g(x) $ with $ int_0^1 frac{1}{g(x)} dx < infty. $ A priori this energy is not bounded below due to the presence of a nonlocal term in the energy. Nevertheless, through a careful analysis of a minimizing sequence we prove existence of global energy minimizers that connect the two wells at infinity. These minimizers are shown to be the classical solutions of the associated nonlocal Ginzburg-Landau type equation.
我们研究了一维版本的标量金兹堡-朗道方程的分层解,该方程涉及二阶空间导数和分数半导数的混合,以及周期调制非线性。这个方程表现为一个适当的重归一化分数金兹堡-朗道能量的欧拉-拉格朗日方程,它具有双阱势,乘以1周期变化的非负因子$ g(x) $与$ int_0^1 frac{1}{g(x)} dx < infty. $先验地,由于能量中存在非局域项,该能量不受限制。然而,通过对最小化序列的仔细分析,我们证明了在无穷远处连接两个井的全局能量最小化的存在。这些最小值被证明是相关的非局部金兹堡-朗道型方程的经典解。
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引用次数: 0
Fibonacci signals with timing jitter 具有时序抖动的斐波那契信号
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2023-01-01 DOI: 10.3934/mine.2023076
D. Citrin
The power spectral density of a signal comprised of a sequence of Dirac $ delta $-functions at successive times determined by a Fibonacci sequence is the temporal analog of the well known structure factor for a Fibonacci chain. Such a signal is quasi-periodic and, under suitable choice of parameters, is the temporal analog of a one-dimensional quasicrystal. While the effects of disorder in the spatial case of Fibonacci chains has been studied numerically, having an analytically tractable stochastic model is needed both for the spatial and temporal cases to be able to study these effects as model parameters are varied. Here, we consider the effects of errors in where the $ delta $-functions defining the signal in the temporal case occur, i.e., timing jitter. In this work, we present an analytically tractable theory of how timing jitter affects the power spectral density of Fibonacci signals.
由斐波那契序列确定的连续时间的狄拉克函数序列组成的信号的功率谱密度是众所周知的斐波那契链结构因子的时间模拟。这样的信号是准周期的,在适当的参数选择下,是一维准晶体的时间模拟。虽然无序在斐波那契链的空间情况下的影响已经被数值研究,但由于模型参数的变化,需要一个解析上易于处理的随机模型来研究空间和时间情况下的这些影响。在这里,我们考虑在时间情况下定义信号的$ delta $-函数发生的错误的影响,即定时抖动。在这项工作中,我们提出了时序抖动如何影响斐波那契信号的功率谱密度的分析理论。
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引用次数: 0
Partial regularity for steady double phase fluids 稳定双相流体的部分规律性
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-11-10 DOI: 10.3934/mine.2023088
G. Scilla, B. Stroffolini

We study partial Hölder regularity for nonlinear elliptic systems in divergence form with double-phase growth, modeling double-phase non-Newtonian fluids in the stationary case.

我们研究了具有双相增长的发散形式的非线性椭圆系统的部分Hölder正则性,在稳态情况下模拟了双相非牛顿流体。
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引用次数: 0
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Mathematics in Engineering
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