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Fractal Features of Muscle to Quantify Fatty Infiltration in Aging and Pathology 用肌肉的分形特征量化衰老和病理中的脂肪浸润
IF 5.4 2区 数学 Q1 Mathematics Pub Date : 2024-05-06 DOI: 10.3390/fractalfract8050275
Annamaria Zaia, Martina Zannotti, Lucia Losa, Pierluigi Maponi
The physiological loss OF muscle mass and strength with aging is referred to as “sarcopenia”, whose combined effect with osteoporosis is a serious threat to the elderly, accounting for decreased mobility and increased risk of falls with consequent fractures. In previous studies, we observed a high degree of inter-individual variability in paraspinal muscle fatty infiltration, one of the most relevant indices of muscle wasting. This aspect led us to develop a computerized method to quantitatively characterize muscle fatty infiltration in aging and diseases. Magnetic resonance images of paraspinal muscles from 58 women of different ages (age range of 23–85 years) and physio-pathological status (healthy young, pre-menopause, menopause, and osteoporosis) were used to set up a method based on fractal-derived texture analysis of lean muscle area (contractile muscle) to estimate muscle fatty infiltration. In particular, lacunarity was computed by parameter β from the GBA (gliding box algorithm) curvilinear plot fitted by our hyperbola model function. Succolarity was estimated by parameter µ, for the four main directions through an algorithm implemented with this purpose. The results show that lacunarity, by quantifying muscle fatty infiltration, can discriminate between osteoporosis and healthy aging, while succolarity can separate the other three groups showing similar lacunarity. Therefore, fractal-derived features of contractile muscle, by measuring fatty infiltration, can represent good indices of sarcopenia in aging and disease.
随着年龄的增长,肌肉质量和力量的生理性丧失被称为 "肌肉疏松症",它与骨质疏松症的共同作用对老年人构成严重威胁,导致老年人活动能力下降,跌倒风险增加,进而引发骨折。在之前的研究中,我们观察到脊柱旁肌肉脂肪浸润的个体间差异很大,而脂肪浸润是肌肉萎缩最相关的指标之一。这促使我们开发了一种计算机化方法,用于定量描述衰老和疾病中肌肉脂肪浸润的特征。我们利用 58 位不同年龄(23-85 岁)和生理病理状态(健康青年、绝经前、绝经期和骨质疏松症)的女性脊柱旁肌肉的磁共振图像,建立了一种基于瘦肌面积(收缩肌)分形衍生纹理分析的方法,以估算肌肉脂肪浸润。其中,裂隙度是通过双曲线模型函数拟合的 GBA(滑行盒算法)曲线图中的参数 β 计算得出的。对于四个主要方向的骤变性,则通过为此目的而实施的算法,用参数 µ 进行估算。结果表明,通过量化肌肉脂肪浸润的裂隙度可以区分骨质疏松症和健康衰老,而琥珀色度则可以区分显示类似裂隙度的其他三组。因此,通过测量脂肪浸润,分形衍生的收缩肌特征可以很好地反映衰老和疾病中的肌肉疏松症。
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引用次数: 0
Fractal Numerical Investigation of Mixed Convective Prandtl-Eyring Nanofluid Flow with Space and Temperature-Dependent Heat Source 具有空间和温度相关热源的普朗特-艾林纳米流体混合对流的分形数值研究
IF 5.4 2区 数学 Q1 Mathematics Pub Date : 2024-05-06 DOI: 10.3390/fractalfract8050276
Y. Nawaz, M. Arif, Muavia Mansoor, K. Abodayeh, A. Baazeem
An explicit computational scheme is proposed for solving fractal time-dependent partial differential equations (PDEs). The scheme is a three-stage scheme constructed using the fractal Taylor series. The fractal time order of the scheme is three. The scheme also ensures stability. The approach is utilized to model the time-varying boundary layer flow of a non-Newtonian fluid over both stationary and oscillating surfaces, taking into account the influence of heat generation that depends on both space and temperature. The continuity equation of the considered incompressible fluid is discretized by first-order backward difference formulas, whereas the dimensionless Navier–Stokes equation, energy, and equation for nanoparticle volume fraction are discretized by the proposed scheme in fractal time. The effect of different parameters involved in the velocity, temperature, and nanoparticle volume fraction are displayed graphically. The velocity profile rises as the parameter I grows. We primarily apply this computational approach to analyze a non-Newtonian fluid’s fractal time-dependent boundary layer flow over flat and oscillatory sheets. Considering spatial and temperature-dependent heat generation is a crucial factor that introduces additional complexity to the analysis. The continuity equation for the incompressible fluid is discretized using first-order backward difference formulas. On the other hand, the dimensionless Navier–Stokes equation, energy equation, and the equation governing nanoparticle volume fraction are discretized using the proposed fractal time-dependent scheme.
本文提出了一种用于求解分形时变偏微分方程(PDEs)的显式计算方案。该方案是利用分形泰勒级数构建的三阶段方案。该方案的分形时间阶数为三阶。该方案还确保了稳定性。该方法用于模拟非牛顿流体在静止和振荡表面上的时变边界层流动,同时考虑了取决于空间和温度的热量产生的影响。所考虑的不可压缩流体的连续性方程采用一阶反向差分公式离散化,而无量纲纳维-斯托克斯方程、能量和纳米粒子体积分数方程则采用所提出的分形时间方案离散化。不同参数对速度、温度和纳米粒子体积分数的影响以图形显示。速度曲线随着参数 I 的增大而上升。我们主要应用这种计算方法来分析非牛顿流体在平面和振荡片上随时间变化的边界层流动。考虑与空间和温度相关的热量产生是一个关键因素,它为分析带来了额外的复杂性。不可压缩流体的连续性方程采用一阶反向差分公式离散化。另一方面,无量纲纳维-斯托克斯方程、能量方程和控制纳米粒子体积分数的方程则采用所提出的分形时间相关方案进行离散化。
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引用次数: 0
Fractal Evolution Characteristics on the Three-Dimensional Fractures in Coal Induced by CO2 Phase Transition Fracturing 二氧化碳相变压裂诱发煤炭三维裂缝的分形演化特征
IF 5.4 2区 数学 Q1 Mathematics Pub Date : 2024-05-04 DOI: 10.3390/fractalfract8050273
Zhen Zhang, Gaofeng Liu, Jia-Chi Lin, George Barakos, Ping Chang
To analyze the transformed effect of three-dimensional (3D) fracture in coal by CO2 phase transition fracturing (CO2-PTF), the CO2-PTF experiment under a fracturing pressure of 185 MPa was carried out. Computed Tomography (CT) scanning and fractal theory were used to analyze the 3D fracture structure parameters. The fractal evolution characteristics of the 3D fractures in coal induced by CO2-PTF were analyzed. The results indicate that the CO2 phase transition fracturing coal has the fracture generation effect and fracture expansion-transformation effect, causing the maximum fracture length, fracture number, fracture volume and fracture surface area to be increased by 71.25%, 161.94%, 3970.88% and 1330.03%. The fractal dimension (DN) for fracture number increases from 2.3523 to 2.3668, and the fractal dimension (DV) for fracture volume increases from 2.8440 to 2.9040. The early dynamic high-pressure gas jet stage of CO2-PTF coal influences the fracture generation effect and promotes the generation of 3D fractures with a length greater than 140 μm. The subsequent quasi-static high-pressure gas stage influences the fracture expansion-transformation effect, which promotes the expansion transformation of 3D fractures with a length of less than 140 μm. The 140 μm is the critical value for the fracture expansion-transformation effect and fracture generation effect. Five indicators are proposed to evaluate the 3D fracture evolution in coal caused by CO2-PTF, which can provide theoretical and methodological references for the study of fracture evolution characteristics of other unconventional natural gas reservoirs and their reservoir stimulation.
为分析二氧化碳相变压裂(CO2-PTF)对煤中三维(3D)裂缝的改造效果,进行了压裂压力为 185 兆帕的 CO2-PTF 试验。利用计算机断层扫描(CT)和分形理论分析了三维断裂结构参数。分析了 CO2-PTF 诱导的煤中三维裂缝的分形演化特征。结果表明,CO2 相变压裂煤具有裂缝生成效应和裂缝扩展-变形效应,使最大裂缝长度、裂缝数量、裂缝体积和裂缝表面积分别增加了 71.25%、161.94%、3970.88% 和 1330.03%。压裂数量的分形维度(DN)从 2.3523 增加到 2.3668,压裂体积的分形维度(DV)从 2.8440 增加到 2.9040。CO2-PTF 煤的早期动态高压气体喷射阶段影响了裂缝生成效果,促进了长度大于 140 μm 的三维裂缝的生成。随后的准静态高压气体阶段影响了裂缝扩展-转化效应,促进了长度小于 140 μm 的三维裂缝的扩展转化。140 μm 是压裂膨胀转化效应和压裂生成效应的临界值。提出了评价 CO2-PTF 作用下煤炭三维裂缝演化的五项指标,可为其他非常规天然气储层裂缝演化特征及其储层激励研究提供理论和方法参考。
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引用次数: 0
Volatility Analysis of Financial Time Series Using the Multifractal Conditional Diffusion Entropy Method 利用多分形条件扩散熵法分析金融时间序列的波动性
IF 5.4 2区 数学 Q1 Mathematics Pub Date : 2024-05-04 DOI: 10.3390/fractalfract8050274
M. Mariani, William Kubin, Peter K. Asante, Osei K. Tweneboah
In this article, we introduce the multifractal conditional diffusion entropy method for analyzing the volatility of financial time series. This method utilizes a q-order diffusion entropy based on a q-weighted time lag scale. The technique of conditional diffusion entropy proves valuable for examining bull and bear behaviors in stock markets across various time scales. Empirical findings from analyzing the Dow Jones Industrial Average (DJI) indicate that employing multi-time lag scales offers greater insight into the complex dynamics of highly fluctuating time series, often characterized by multifractal behavior. A smaller time scale like t=2 to t=256 coincides more with the state of the DJI index than larger time scales like t=256 to t=1024. We observe extreme fluctuations in the conditional diffusion entropy for DJI for a short time lag, while smoother or averaged fluctuations occur over larger time lags.
本文介绍了用于分析金融时间序列波动性的多分形条件扩散熵方法。该方法利用基于 q 加权时滞标度的 q 阶扩散熵。事实证明,条件扩散熵技术对于研究股票市场在不同时间尺度上的牛市和熊市行为非常有价值。分析道琼斯工业平均指数(DJI)的经验结果表明,采用多时间滞后标度可以更深入地了解高度波动的时间序列的复杂动态,这些时间序列通常具有多分形行为的特征。与 t=256 到 t=1024 等较大的时间尺度相比,t=2 到 t=256 等较小的时间尺度与道琼斯工业平均指数的状态更为吻合。我们观察到,在较短的时间滞后期,道琼斯工业平均指数的条件扩散熵波动剧烈,而在较大的时间滞后期,波动则较为平滑或平均。
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引用次数: 0
Optimizing Variational Problems through Weighted Fractional Derivatives 通过加权分式导数优化变量问题
IF 5.4 2区 数学 Q1 Mathematics Pub Date : 2024-05-02 DOI: 10.3390/fractalfract8050272
Ricardo Almeida
In this article, we explore a variety of problems within the domain of calculus of variations, specifically in the context of fractional calculus. The fractional derivative we consider incorporates the notion of weighted fractional derivatives along with derivatives with respect to another function. Besides the fractional operators, the Lagrange function depends on extremal points. We examine the fundamental problem, providing the fractional Euler–Lagrange equation and the associated transversality conditions. Both the isoperimetric and Herglotz problems are also explored. Finally, we conclude with an analysis of the variational problem, incorporating fractional derivatives of any positive real order.
在本文中,我们将探讨变分微积分领域内的各种问题,特别是在分数微积分的背景下。我们所考虑的分数导数包含了加权分数导数的概念以及相对于另一个函数的导数。除了分数算子,拉格朗日函数还取决于极值点。我们研究了基本问题,提供了分数欧拉-拉格朗日方程和相关的横向条件。我们还探讨了等周问题和赫格洛茨问题。最后,我们对变分问题进行了分析,其中包含任意正实阶的分数导数。
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引用次数: 0
Dynamic Analysis and Field-Programmable Gate Array Implementation of a 5D Fractional-Order Memristive Hyperchaotic System with Multiple Coexisting Attractors 具有多个共存吸引子的 5D 分数阶膜超混沌系统的动态分析与现场可编程门阵列实现
IF 5.4 2区 数学 Q1 Mathematics Pub Date : 2024-05-01 DOI: 10.3390/fractalfract8050271
Fei Yu, Wuxiong Zhang, Xiaoli Xiao, Wei Yao, Shuo Cai, Jin Zhang, Chunhua Wang, Yi Li
On the basis of the chaotic system proposed by Wang et al. in 2023, this paper constructs a 5D fractional-order memristive hyperchaotic system (FOMHS) with multiple coexisting attractors through coupling of magnetic control memristors and dimension expansion. Firstly, the divergence, Kaplan–Yorke dimension, and equilibrium stability of the chaotic model are studied. Subsequently, we explore the construction of the 5D FOMHS, introducing the definitions of the Caputo differential operator and the Riemann–Liouville integral operator and employing the Adomian resolving approach to decompose the linears, the nonlinears, and the constants of the system. The complex dynamic characteristics of the system are analyzed by phase diagrams, Lyapunov exponent spectra, time-domain diagrams, etc. Finally, the hardware circuit of the proposed 5D FOMHS is performed by FPGA, and its randomness is verified using the NIST tool.
本文在2023年Wang等人提出的混沌系统基础上,通过磁控忆阻器耦合和维数扩展,构建了一个具有多个共存吸引子的5维分数阶忆阻器超混沌系统(FOMHS)。首先,研究了混沌模型的发散性、Kaplan-Yorke维数和平衡稳定性。随后,我们探讨了 5D FOMHS 的构建,引入了 Caputo 微分算子和黎曼-刘维尔积分算子的定义,并采用 Adomian 解析法分解了系统的线性、非线性和常数。通过相图、Lyapunov 指数谱、时域图等分析了系统的复杂动态特性。最后,通过 FPGA 实现了所提出的 5D FOMHS 的硬件电路,并使用 NIST 工具验证了其随机性。
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引用次数: 0
Finite-Time Adaptive Event-Triggered Control for Full States Constrained FONSs with Uncertain Parameters and Disturbances 具有不确定参数和干扰的全状态受限 FONS 的有限时间自适应事件触发控制
IF 5.4 2区 数学 Q1 Mathematics Pub Date : 2024-04-25 DOI: 10.3390/fractalfract8050249
Changhui Wang, Wencheng Li, Mei Liang
This article focuses the event-triggered adaptive finite-time control scheme for the states constrained fractional-order nonlinear systems (FONSs) under uncertain parameters and external disturbances. The backstepping scheme is employed to construct the finite-time controller via a series of barrier Lyapunov function (BLF) to solve that all the state constraints are not violated. Different from the trigger condition with fixed value, the event-triggered strategy is applied to overcome the communication burden of controller caused by the limited communication resources. By utilizing fractional-order Lyapunov analysis, all variables in the resulted system are proven to be bounded, and the tracking error converges to the small neighborhood around origin in finite time and without the Zeno behavior. Finally, the effectiveness of the proposed control scheme is verified by the simulation analysis of a bus power system.
本文主要针对不确定参数和外部扰动下的状态约束分数阶非线性系统(FONS),提出了事件触发自适应有限时间控制方案。该方案采用后步法(backstepping),通过一系列障碍李亚普诺夫函数(BLF)来构建有限时间控制器,以确保不违反所有状态约束。与固定值的触发条件不同,采用了事件触发策略,以克服有限通信资源给控制器带来的通信负担。通过利用分数阶 Lyapunov 分析,证明了结果系统中的所有变量都是有界的,跟踪误差在有限时间内收敛到原点周围的小邻域,并且没有 Zeno 行为。最后,通过对总线电力系统的仿真分析,验证了所提控制方案的有效性。
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引用次数: 0
A Novel Application of Fractional Order Derivative Moth Flame Optimization Algorithm for Solving the Problem of Optimal Coordination of Directional Overcurrent Relays 分数阶衍生蛾焰优化算法在解决定向过流继电器优化协调问题中的新应用
IF 5.4 2区 数学 Q1 Mathematics Pub Date : 2024-04-25 DOI: 10.3390/fractalfract8050251
Abdul Wadood, Herie Park
The proper coordination of directional overcurrent relays (DOCRs) is crucial in electrical power systems. The coordination of DOCRs in a multi-loop power system is expressed as an optimization problem. The aim of this study focuses on improving the protection system’s performance by minimizing the total operating time of DOCRs via effective coordination with main and backup DOCRs while keeping the coordination constraints within allowable limits. The coordination problem of DOCRs is solved by developing a new application strategy called Fractional Order Derivative Moth Flame Optimizer (FODMFO). This approach involves incorporating the ideas of fractional calculus (FC) into the mathematical model of the conventional moth flame algorithm to improve the characteristics of the optimizer. The FODMFO approach is then tested on the coordination problem of DOCRs in standard power systems, specifically the IEEE 3, 8, and 15 bus systems as well as in 11 benchmark functions including uni- and multimodal functions. The results obtained from the proposed method, as well as its comparison with other recently developed algorithms, demonstrate that the combination of FOD and MFO improves the overall efficiency of the optimizer by utilizing the individual strengths of these tools and identifying the globally optimal solution and minimize the total operating time of DOCRs up to an optimal value. The reliability, strength, and dependability of FODMFO are supported by a thorough statistics study using the box-plot, histograms, empirical cumulative distribution function demonstrations, and the minimal fitness evolution seen in each distinct simulation. Based on these data, it is evident that FODMFO outperforms other modern nature-inspired and conventional algorithms.
在电力系统中,正确协调定向过流继电器(DOCR)至关重要。多回路电力系统中 DOCR 的协调问题是一个优化问题。本研究的目的在于通过与主用和备用 DOCR 的有效协调,最大限度地减少 DOCR 的总运行时间,同时将协调约束条件控制在允许范围内,从而提高保护系统的性能。DOCR 的协调问题是通过开发一种新的应用策略来解决的,这种策略被称为分数阶衍生蛾式火焰优化器(FODMFO)。这种方法将分数微积分(FC)的思想融入到传统蛾焰算法的数学模型中,以改善优化器的特性。然后,FODMFO 方法在标准电力系统中的 DOCR 协调问题上进行了测试,特别是 IEEE 3、8 和 15 总线系统,以及包括单模和多模函数在内的 11 个基准函数。所提方法得出的结果以及与最近开发的其他算法的比较表明,FOD 和 MFO 的组合利用了这些工具的各自优势,提高了优化器的整体效率,找出了全局最优解,并将 DOCR 的总运行时间最小化到最优值。通过使用箱形图、直方图、经验累积分布函数演示和在每个不同模拟中看到的最小适配性演化进行全面的统计研究,FODMFO 的可靠性、优势和可靠性得到了支持。基于这些数据,FODMFO 显然优于其他现代自然启发算法和传统算法。
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引用次数: 0
Existence and Uniqueness Result for Fuzzy Fractional Order Goursat Partial Differential Equations 模糊分阶高萨特偏微分方程的存在性和唯一性结果
IF 5.4 2区 数学 Q1 Mathematics Pub Date : 2024-04-25 DOI: 10.3390/fractalfract8050250
Muhammad Sarwar, Noor Jamal, K. Abodayeh, C. Promsakon, T. Sitthiwirattham
In this manuscript, we discuss fractional fuzzy Goursat problems with Caputo’s gH-differentiability. The second-order mixed derivative term in Goursat problems and two types of Caputo’s gH-differentiability pose challenges to dealing with Goursat problems. Therefore, in this study, we convert Goursat problems to equivalent systems fuzzy integral equations to deal properly with the mixed derivative term and two types of Caputo’s gH-differentiability. In this study, we utilize the concept of metric fixed point theory to discuss the existence of a unique solution of fractional fuzzy Goursat problems. For the useability of established theoretical work, we provide some numerical problems. We also discuss the solutions to numerical problems by conformable double Laplace transform. To show the validity of the solutions we provide 3D plots. We discuss, as an application, why fractional partial fuzzy differential equations are the generalization of usual partial fuzzy differential equations by providing a suitable reason. Moreover, we show the advantages of the proposed fractional transform over the usual Laplace transform.
在本手稿中,我们讨论了具有卡普托 gH 微分性质的分数模糊 Goursat 问题。Goursat 问题中的二阶混合导数项和两种 Caputo's gH 微分性给 Goursat 问题的处理带来了挑战。因此,在本研究中,我们将 Goursat 问题转换为等价系统模糊积分方程,以正确处理混合导数项和两种卡普托 gH 微分。在本研究中,我们利用度量定点理论的概念来讨论分数模糊 Goursat 问题唯一解的存在性。为了使已建立的理论工作更易于使用,我们提供了一些数值问题。我们还讨论了用保形双拉普拉斯变换解决数值问题的方法。为了显示解法的有效性,我们提供了三维图。作为应用,我们讨论了为什么分数偏模糊微分方程是普通偏模糊微分方程的一般化,并提供了适当的理由。此外,我们还展示了所提出的分数变换相对于普通拉普拉斯变换的优势。
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引用次数: 0
Impressive Exact Solitons to the Space-Time Fractional Mathematical Physics Model via an Effective Method 通过有效方法对时空分数数学物理模型进行令人印象深刻的精确索解
IF 5.4 2区 数学 Q1 Mathematics Pub Date : 2024-04-24 DOI: 10.3390/fractalfract8050248
Abdulaziz Khalid Alsharidi, Moin-ud-Din Junjua
A new class of truncated M-fractional exact soliton solutions for a mathematical physics model known as a truncated M-fractional (1+1)-dimensional nonlinear modified mixed-KdV model are achieved. We obtain these solutions by using a modified extended direct algebraic method. The obtained results consist of trigonometric, hyperbolic trigonometric and mixed functions. We also discuss the effect of fractional order derivative. To validate our results, we utilized the Mathematica software. Additionally, we depict some of the obtained kink, periodic, singular, and kink-singular wave solitons, using two and three dimensional graphs. The obtained results are useful in the fields of fluid dynamics, nonlinear optics, ocean engineering and others. Furthermore, these employed techniques are not only straightforward, but also highly effective when used to solve non-linear fractional partial differential equations (FPDEs).
针对一个数学物理模型,即截断 M 分(1+1)维非线性修正混合-KdV 模型,我们得到了一类新的截断 M 分精确孤子解。我们使用改进的扩展直接代数方法获得了这些解。得到的结果包括三角函数、双曲三角函数和混合函数。我们还讨论了分数阶导数的影响。为了验证我们的结果,我们使用了 Mathematica 软件。此外,我们还利用二维和三维图形描绘了所获得的一些扭结波、周期波、奇异波和扭结奇异波孤子。所获得的结果在流体动力学、非线性光学、海洋工程等领域非常有用。此外,这些采用的技术不仅简单明了,而且在用于求解非线性分数偏微分方程(FPDE)时非常有效。
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引用次数: 0
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Fractal and Fractional
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