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Existence Result for Coupled Random First-Order Impulsive Differential Equations with Infinite Delay 具有无限延迟的耦合随机一阶脉冲微分方程的存在性结果
IF 5.4 2区 数学 Q1 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-21 DOI: 10.3390/fractalfract8010010
Abdelkader Moumen, F. Z. Ladrani, Mohamed Ferhat, Amin Benaissa Cherif, Mohamed Bouye, Keltoum Bouhali
In this paper, we consider a system of random impulsive differential equations with infinite delay. When utilizing the nonlinear variation of Leray–Schauder’s fixed-point principles together with a technique based on separable vector-valued metrics to establish sufficient conditions for the existence of solutions, under suitable assumptions on Y1, Y2 and ϖ1, ϖ2, which greatly enriched the existence literature on this system, there is, however, no hope to discuss the uniqueness result in a convex case. In the present study, we analyzed the influence of the impulsive and infinite delay on the solutions to our system. In addition, to the best of our acknowledge, there is no result concerning coupled random system in the presence of impulsive and infinite delay.
在本文中,我们考虑了一个具有无限延迟的随机脉冲微分方程系统。在对 Y1、Y2 和 ϖ1、ϖ2 进行适当假设的情况下,利用 Leray-Schauder 定点原理的非线性变化以及基于可分离向量值度量的技术来建立解存在性的充分条件,这极大地丰富了有关该系统的存在性文献,然而,在凸情况下讨论唯一性结果却没有希望。在本研究中,我们分析了脉冲和无限延迟对系统解的影响。此外,据我们所知,目前还没有关于存在冲动和无限延迟的耦合随机系统的结果。
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引用次数: 0
Stability Analysis of Finite Time for a Class of Nonlinear Time-Delay Fractional-Order Systems 一类非线性时延分数阶系统的有限时间稳定性分析
IF 5.4 2区 数学 Q1 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-20 DOI: 10.3390/fractalfract8010004
A. Ben Makhlouf, Lassaad Mchiri, Mohamed Rhaima
In this study, we delve into the examination of Finite Time Stability (FTS) within a specific class of Fractional-Order Systems (FOS) with time delays. By applying a fixed-point theorem, we establish novel sufficient conditions to ensure FTS for time-delayed FOS within  1<σ<2. Moreover, we investigate the existence and uniqueness of global solutions for this particular system. To demonstrate the credibility of our results, we substantiate our findings through the presentation of two illustrative examples.
在本研究中,我们深入探讨了带有时间延迟的特定分数阶系统(FOS)中的有限时间稳定性(FTS)。通过应用定点定理,我们建立了新的充分条件,以确保时延 FOS 在 1<σ<2 范围内的有限时间稳定性。为了证明我们结果的可信性,我们通过两个示例来证实我们的发现。
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引用次数: 0
Finite Difference Modeling of Time Fractal Impact on Unsteady Magneto-hydrodynamic Darcy–Forchheimer Flow in Non-Newtonian Nanofluids with the q-Derivative 用 q 衍生法建立时间分形对非牛顿纳米流体中的非稳态磁流体动力学达西-福克海默流动影响的有限差分模型
IF 5.4 2区 数学 Q1 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-20 DOI: 10.3390/fractalfract8010008
A. Baazeem, Y. Nawaz, M. Arif
This contribution addresses a fractal numerical scheme that can be employed for handling fractal time-dependent parabolic equations. The numerical scheme presented in this contribution can be used to discretize integer order and fractal derivatives in a given differential equation. Therefore, the scheme and results can be used for both cases. The proposed finite difference scheme is based on two stages. Fractal time derivatives are discretized by employing the proposed approach. For the scalar convection–diffusion equation, we derive the stability condition of the proposed fractal scheme. Using a nonlinear chemical reaction, the approach is also used to solve the Quantum Calculus model of a Williamson nanofluid’s unsteady Darcy–Forchheimer flow over flat and oscillatory sheets. The findings indicate a negative correlation between the velocity profile and the porosity parameter and inertia coefficient, with an increase in these factors resulting in a drop in the velocity profile. Additionally, the fractal scheme under consideration is being compared to the fractal Crank–Nicolson method, revealing that the proposed scheme exhibits a superior convergence speed compared to the fractal Crank–Nicolson method. Several problems involving the motion of non-Newtonian nanofluids through magnetic fields and porous media can be investigated with the help of the proposed numerical scheme. This research has implications for developing more efficient heat transfer and energy conversion devices based on nanofluids.
这篇论文探讨了一种可用于处理分形时变抛物方程的分形数值方案。本论文中介绍的数值方案可用于给定微分方程中整阶导数和分形导数的离散化。因此,该方案和结果可同时用于这两种情况。所提出的有限差分方案基于两个阶段。分形时间导数采用所提出的方法进行离散化。对于标量对流扩散方程,我们推导出了拟议分形方案的稳定性条件。利用非线性化学反应,该方法还用于求解威廉姆森纳米流体在平面和振荡片上的非稳态达西-福克海默流动的量子计算模型。研究结果表明,速度曲线与孔隙度参数和惯性系数之间存在负相关关系,这些因素的增加会导致速度曲线的下降。此外,还将所考虑的分形方案与分形 Crank-Nicolson 方法进行了比较,结果表明,与分形 Crank-Nicolson 方法相比,所提出的方案具有更高的收敛速度。在提出的数值方案的帮助下,可以研究涉及非牛顿纳米流体通过磁场和多孔介质运动的若干问题。这项研究对开发基于纳米流体的更高效传热和能量转换设备具有重要意义。
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引用次数: 0
Geometric Properties and Hardy Spaces of Rabotnov Fractional Exponential Functions 拉波特诺夫分指数函数的几何性质和哈代空间
IF 5.4 2区 数学 Q1 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-20 DOI: 10.3390/fractalfract8010005
Mohsan Raza, D. Breaz, Saima Mushtaq, Luminița-Ioana Cotîrlă, F. Tawfiq, Eleonora Rapeanu
The aim of this study is to investigate a certain sufficiency criterion for uniform convexity, strong starlikeness, and strong convexity of Rabtonov fractional exponential functions. We also study the starlikeness and convexity of order γ. Moreover, we find conditions so that the Rabotnov functions belong to the class of bounded analytic functions and Hardy spaces. Various consequences of these results are also presented.
本研究旨在探究拉博特诺夫分数指数函数的均匀凸性、强星点性和强凸性的某个充分性准则。此外,我们还找到了使拉博特诺夫函数属于有界解析函数和哈代空间的条件。我们还介绍了这些结果的各种后果。
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引用次数: 0
Optimal Design of Fractional-Order PID Controllers for a Nonlinear AWS Wave Energy Converter Using Hybrid Jellyfish Search and Particle Swarm Optimization 使用混合水母搜索和粒子群优化法优化非线性 AWS 波能转换器的分数阶 PID 控制器设计
IF 5.4 2区 数学 Q1 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-20 DOI: 10.3390/fractalfract8010006
Ziad M. Ali, Ahmed Mahdy Ahmed, H. Hasanien, S. Aleem
In this study, a nonlinear Archimedes wave swing (AWS) energy conversion system was employed to enable the use of irregular sea waves to provide useful electricity. Instead of the conventional PI controllers used in prior research, this study employed fractional-order PID (FOPID) controllers to control the back-to-back configuration of AWS. The aim was to maximize the energy yield from waves and maintain the grid voltage and the capacitor DC link voltage at predetermined values. In this study, six FOPID controllers were used to accomplish the control goals, leading to an array of thirty parameters required to be fine-tuned. In this regard, a hybrid jellyfish search optimizer and particle swarm optimization (HJSPSO) algorithm was adopted to select the optimal control gains. Verification of the performance of the proposed FOPID control system was achieved by comparing the system results to two conventional PID controllers and one FOPID controller. The conventional PID controllers were tuned using a recently presented metaheuristic algorithm called the Coot optimization algorithm (COOT) and the classical particle swarm optimization algorithm (PSO). Moreover, the FOPID was also tuned using the well-known genetic algorithm (GA). The system investigated in this study was subjected to various unsymmetrical and symmetrical fault disturbances. When compared with the standard COOT-PID, PSO-PID, and GA-FOPID controllers, the HJSPSO-FOPID results show a significant improvement in terms of performance and preserving control goals during system instability
本研究采用了非线性阿基米德摆浪(AWS)能量转换系统,以便利用不规则海浪提供有用的电力。与以往研究中使用的传统 PI 控制器不同,本研究采用了分数阶 PID (FOPID) 控制器来控制 AWS 的背靠背配置。其目的是最大限度地利用海浪产生的能量,并将电网电压和电容器直流链路电压保持在预定值。在这项研究中,使用了六个 FOPID 控制器来实现控制目标,因此需要对 30 个参数进行微调。为此,采用了混合水母搜索优化器和粒子群优化(HJSPSO)算法来选择最佳控制增益。通过将系统结果与两个传统 PID 控制器和一个 FOPID 控制器进行比较,验证了所提出的 FOPID 控制系统的性能。对传统 PID 控制器的调整采用了最近提出的元启发式算法--Coot 优化算法 (COOT) 和经典的粒子群优化算法 (PSO)。此外,还使用著名的遗传算法 (GA) 对 FOPID 进行了调整。本研究调查的系统受到了各种非对称和对称故障干扰。与标准 COOT-PID、PSO-PID 和 GA-FOPID 控制器相比,HJSPSO-FOPID 的结果表明,在系统不稳定时,其性能和保持控制目标的能力都有显著提高。
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引用次数: 0
Fractional-Order Modeling of Piezoelectric Actuators with Coupled Hysteresis and Creep Effects 具有耦合磁滞和蠕变效应的压电致动器的分数阶建模
IF 5.4 2区 数学 Q1 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-19 DOI: 10.3390/fractalfract8010003
Yifan Xu, Ying Luo, Xin Luo, Yangquan Chen, Wei Liu
A novel fractional-order model, incorporating coupled hysteresis and creep effects, is proposed for typical piezoelectric actuators in this study. Throughout the actuation process, various nonlinear behaviors such as piezoelectric hysteresis, non-local memory, peak transition, and creep nonlinearity are accurately characterized by the model. Offering a simpler structure and superior tracking performance compared to conventional models, the proposed fractional-order model parameters are identified using a method that integrates actuator dynamics and employs the particle swarm optimization algorithm. Experimental validation on a piezoelectric actuation platform confirms the model’s superior accuracy and simplified structure, contributing to a deeper understanding of piezoelectric actuation mechanisms and providing an efficient modeling tool for enhanced system performance.
本研究针对典型的压电致动器提出了一种新的分数阶模型,该模型包含了耦合滞后和蠕变效应。在整个致动过程中,该模型准确地描述了压电滞后、非局部记忆、峰值转换和蠕变非线性等各种非线性行为。与传统模型相比,所提出的分数阶模型结构更简单,跟踪性能更优越,模型参数的确定采用了整合致动器动力学并使用粒子群优化算法的方法。在压电致动平台上进行的实验验证证实了该模型的卓越准确性和简化结构,有助于加深对压电致动机制的理解,并为提高系统性能提供了有效的建模工具。
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引用次数: 0
Fractional Criticality Theory and Its Application in Seismology 分数临界理论及其在地震学中的应用
IF 5.4 2区 数学 Q1 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-18 DOI: 10.3390/fractalfract7120890
B. Shevtsov, O. Sheremetyeva
To understand how the temporal non-locality («memory») properties of a process affect its critical regimes, the power-law compound and time-fractional Poisson process is presented as a universal hereditary model of criticality. Seismicity is considered as an application of the theory of criticality. On the basis of the proposed hereditarian criticality model, the critical regimes of seismicity are investigated. It is shown that the seismic process has the property of «memory» (non-locality over time) and statistical time-dependence of events. With a decrease in the fractional exponent of the Poisson process, the relaxation slows down, which can be associated with the hardening of the medium and the accumulation of elastic energy. Delayed relaxation is accompanied by an abnormal increase in fluctuations, which is caused by the non-local correlations of random events over time. According to the found criticality indices, the seismic process is in subcritical regimes for the zero and first moments and in supercritical regimes for the second statistical moment of events’ reoccurrence frequencies distribution. The supercritical regimes indicate the instability of the deformation changes that can go into a non-stationary regime of a seismic process.
为了了解过程的时间非位置性("记忆")特性如何影响其临界状态,提出了幂律复合和时间分数泊松过程作为临界性的通用遗传模型。地震被视为临界理论的一种应用。根据所提出的遗传临界模型,研究了地震的临界体制。研究表明,地震过程具有 "记忆 "特性(时间上的非位置性)和事件的统计时间依赖性。随着泊松过程分数指数的减小,松弛速度减慢,这可能与介质的硬化和弹性能量的积累有关。延迟松弛伴随着波动的异常增加,这是由随机事件随时间变化的非局部相关性引起的。根据所发现的临界指数,地震过程的零时刻和第一时刻处于亚临界状态,事件重现频率分布的第二统计时刻处于超临界状态。超临界状态表明变形变化的不稳定性,可进入地震过程的非稳态状态。
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引用次数: 0
Solitary Waves Propagation Analysis in Nonlinear Dynamical System of Fractional Coupled Boussinesq-Whitham-Broer-Kaup Equation 分数耦合 Boussinesq-Whitham-Broer-Kaup 方程非线性动力系统中的孤波传播分析
IF 5.4 2区 数学 Q1 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-18 DOI: 10.3390/fractalfract7120889
M. M. Al-Sawalha, S. Mukhtar, Rasool Shah, A. Ganie, Khaled Moaddy
The primary goal of this study is to create and characterise solitary wave solutions for the conformable Fractional Coupled Boussinesq-Whitham-Broer-Kaup Equations (FCBWBKEs), a model that governs shallow water waves. Through wave transformations and the chain rule, the authors used the modified Extended Direct Algebraic Method (mEDAM) for transforming FCBWBKEs into a more manageable Nonlinear Ordinary Differential Equation (NODE). This accomplishment is particularly noteworthy because it surpasses the drawbacks linked to both the Caputo and Riemann–Liouville definitions in complying to the chain rule. The study uses visual representations such as 3D, 2D, and contour graphs to demonstrate the dynamic nature of solitary wave solutions. Furthermore, the investigation of diverse wave phenomena such as kinks, shock waves, periodic waves, and bell-shaped kink waves highlights the range of knowledge obtained in the study of shallow water wave behavior. Overall, this study introduces novel methodologies that produce valuable and consistent results for the problem under consideration.
本研究的主要目标是创建并表征控制浅水波浪的模型--保角耦合布西内斯克-维瑟姆-布罗尔-考普方程(FCBWBKEs)的孤波解。通过波浪变换和链式法则,作者使用修正的扩展直接代数法(mEDAM)将 FCBWBKEs 转换为更易于管理的非线性常微分方程(NODE)。这一成果尤其值得注意,因为它超越了卡普托定义和黎曼-黎欧维尔定义在遵守链式规则方面的缺点。研究使用三维、二维和等值线图等可视化表示方法来展示孤波解的动态性质。此外,对各种波现象(如扭结波、冲击波、周期波和钟形扭结波)的研究突出了在浅水波行为研究中获得的知识范围。总之,本研究引入了新颖的方法,为所考虑的问题提供了有价值且一致的结果。
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引用次数: 0
Exploiting Newly Designed Fractional-Order 3D Lorenz Chaotic System and 2D Discrete Polynomial Hyper-Chaotic Map for High-Performance Multi-Image Encryption 利用新设计的分数阶三维洛伦兹混沌系统和二维离散多项式超混沌图实现高性能多图像加密
IF 5.4 2区 数学 Q1 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-16 DOI: 10.3390/fractalfract7120887
Wei Feng, Quanwen Wang, Hui Liu, Yu Ren, Junhao Zhang, Shubo Zhang, Kun Qian, Heping Wen
Chaos-based image encryption has become a prominent area of research in recent years. In comparison to ordinary chaotic systems, fractional-order chaotic systems tend to have a greater number of control parameters and more complex dynamical characteristics. Thus, an increasing number of researchers are introducing fractional-order chaotic systems to enhance the security of chaos-based image encryption. However, their suggested algorithms still suffer from some security, practicality, and efficiency problems. To address these problems, we first constructed a new fractional-order 3D Lorenz chaotic system and a 2D sinusoidally constrained polynomial hyper-chaotic map (2D-SCPM). Then, we elaborately developed a multi-image encryption algorithm based on the new fractional-order 3D Lorenz chaotic system and 2D-SCPM (MIEA-FCSM). The introduction of the fractional-order 3D Lorenz chaotic system with the fourth parameter not only enables MIEA-FCSM to have a significantly large key space but also enhances its overall security. Compared with recent alternatives, the structure of 2D-SCPM is simpler and more conducive to application implementation. In our proposed MIEA-FCSM, multi-channel fusion initially reduces the number of pixels to one-sixth of the original. Next, after two rounds of plaintext-related chaotic random substitution, dynamic diffusion, and fast scrambling, the fused 2D pixel matrix is eventually encrypted into the ciphertext one. According to numerous experiments and analyses, MIEA-FCSM obtained excellent scores for key space (2541), correlation coefficients (<0.004), information entropy (7.9994), NPCR (99.6098%), and UACI (33.4659%). Significantly, MIEA-FCSM also attained an average encryption rate as high as 168.5608 Mbps. Due to the superiority of the new fractional-order chaotic system, 2D-SCPM, and targeted designs, MIEA-FCSM outperforms many recently reported leading image encryption algorithms.
近年来,基于混沌的图像加密已成为一个突出的研究领域。与普通混沌系统相比,分数阶混沌系统往往具有更多的控制参数和更复杂的动态特性。因此,越来越多的研究人员开始引入分数阶混沌系统来增强基于混沌的图像加密的安全性。然而,他们提出的算法仍然存在一些安全性、实用性和效率方面的问题。为了解决这些问题,我们首先构建了一个新的分数阶三维洛伦兹混沌系统和一个二维正弦约束多项式超混沌图(2D-SCPM)。然后,我们基于新的分数阶三维洛伦兹混沌系统和2D-SCPM(MIEA-FCSM)精心开发了一种多图像加密算法。引入带有第四参数的分数阶三维洛伦兹混沌系统不仅使MIEA-FCSM的密钥空间显著增大,而且增强了其整体安全性。与最近的替代方案相比,2D-SCPM的结构更简单,更有利于应用实现。在我们提出的 MIEA-FCSM 中,多通道融合首先将像素数量减少到原来的六分之一。然后,经过两轮与明文相关的混沌随机置换、动态扩散和快速加扰,最终将融合后的二维像素矩阵加密为密文矩阵。根据大量实验和分析,MIEA-FCSM 在密钥空间(2541)、相关系数(<0.004)、信息熵(7.9994)、NPCR(99.6098%)和 UACI(33.4659%)等方面都获得了优异的成绩。值得注意的是,MIEA-FCSM 的平均加密速率也高达 168.5608 Mbps。由于新的分数阶混沌系统、二维SCPM和针对性设计的优越性,MIEA-FCSM的性能超过了最近报道的许多领先的图像加密算法。
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引用次数: 0
Complex Rayleigh–van-der-Pol–Duffing Oscillators: Dynamics, Phase, Antiphase Synchronization, and Image Encryption 复杂的 Rayleigh-van-der-Pol-Duffing 振荡器:动力学、相位、反相同步和图像加密
IF 5.4 2区 数学 Q1 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-15 DOI: 10.3390/fractalfract7120886
A. Al Themairi, G. Mahmoud, A. Farghaly, T. Abed-Elhameed
This paper introduces the complex Rayleigh–van-der- Pol–Duffing oscillators (RVDOs), which are hyperchaotic and can be autonomous or nonautonomous. The fundamental dynamics of the autonomous and nonautonomous complex RVDOs, including dissipation, symmetry, fixed points, and stability, are studied. These oscillators are found in various necessary fields of physics and engineering. The paper proposes a scheme to achieve phase synchronization (PS) and antiphase synchronization (APS) for different dimensional models. These kinds of synchronization are considered a generalization of several other types of synchronization. We use the active control method based on Lyapunov’s stability theory for this scheme. By analytically determining the control functions, the scheme achieved PS and APS. Our scheme is applied to study the PS of hyperchaotic behaviors for two distinct hyperchaotic nonautonomous and autonomous complex RVDOs. Additionally, the scheme is employed to achieve the APS of a chaotic real nonautonomous RVDO and a hyperchaotic complex autonomous RVDO, including those with different dimensions. Our work presents numerical results that plot the amplitudes and phases of these hyperchaotic behaviors, demonstrating the achievement of the PS and APS. The encryption and decryption of grayscale images are researched based on APS. The experimental results of image encryption and decryption are computed with information entropy, visual analysis, and histograms.
本文介绍了复杂的雷利-范-德-波尔-杜芬振荡器(RVDOs),这种振荡器是超混沌的,可以是自主的,也可以是非自主的。本文研究了自主和非自主复杂 RVDO 的基本动力学,包括耗散、对称性、定点和稳定性。这些振荡器存在于物理学和工程学的各个必要领域。本文提出了一种针对不同维度模型实现相位同步(PS)和反相位同步(APS)的方案。这些同步被认为是其他几种同步的概括。我们在此方案中使用了基于 Lyapunov 稳定性理论的主动控制方法。通过分析确定控制函数,该方案实现了 PS 和 APS。我们的方案被用于研究两种不同的超混沌非自主和自主复杂 RVDO 的超混沌行为的 PS。此外,该方案还用于实现混沌实非自主 RVDO 和超混沌复自主 RVDO 的 APS,包括那些具有不同维度的 RVDO。我们的工作展示了绘制这些超混沌行为的振幅和相位的数值结果,证明了 PS 和 APS 的实现。基于 APS 研究了灰度图像的加密和解密。利用信息熵、视觉分析和直方图计算了图像加密和解密的实验结果。
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